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Costa, Josiane Moreira da. "Acesso a terapia medicamentosa na perspectiva de pacientes e profissionais de saúde." Universidade Federal de Minas Gerais, 2012. http://hdl.handle.net/1843/DLCC-8ZUGRF.
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Case study with qualitative approach based on comprehensive sociology aiming at understanding the access to medications during pre, intra and post-hospitalization, according to perspectives from users and health professionals of a teaching hospital. The studys scenario is a large general teaching hospital that is reference in trauma, urgent care and emergency located at the North of Belo Horizonte. Seven patients,nine companions and 14 health professionals, a total of 30 participants, were the subjects determined by data saturation. Data was collected through interviews based on a semi-structured script for each segment. The data was submitted to content analysis and organized in four categories: 1. From the medications that I take to the ones I dont know: in the hands of health professionals; subdivided into two subcategories Patients (in) activity vs. professional tecnicism and Hospital admission and discharge as landmarks to the caring transition; 2. (Des) continuity ofdrug therapy; 3. Information as medications access strategy; 4. Possibleaccessibility. Results show that medications earn greater or lesser projection in the patients care besides being one of the strategies of health care in hospitalization. Thus, access to drug therapy becomes heterogeneous and permeated by values, relations and subjectivities provoking feelings based on the understanding of the need to medication use, fear of re-hospitalization, non-availability of drug therapy in the Primary Health Care Unities and the users inability to buy medication. Despite programs which offer medication supplies, access to them in the pre and posthospitalization periods is fragile constituting one of the factors which strengthen the patients cyclical walk in the health care net. The access barriers regarding information present themselves as a complex issue which involves different work processes permeated by both patient-professional relationships and interprofessional ones. However, information is essential to guarantee access to drug therapy in order to avoid compromising medication supplies, prescription and availability. Early discharge preparation, referencing mechanisms implantation and patients subjectivities acknowledgement are some of the activities which contribute to guarantee medication access. As a conclusion, drug therapy is built from relationships and experiences lived by the actors involved and reveals itself an important technology to caring in every level of health care.Estudo de caso de abordagem qualitativa fundamentada na sociologia compreensiva com o objetivo de compreender o acesso a medicamentos nos momentos pré, intra e pós-internação hospitalar, segundo perspectivas dos usuários e profissionais de saúde de um hospital de ensino. O cenário de estudo foi um hospital de ensinogeral, de grande porte e referência em trauma, urgência e emergência, localizado na região norte do município de Belo Horizonte. Os sujeitos foram sete pacientes, nove acompanhantes e 14 profissionais de saúde, em um total de 30 participantes, determinados por saturação de dados. A coleta de dados foi por meio de entrevistas a partir de um roteiro semiestruturado para cada segmento. Os dados foram submetidos à análise de conteúdo e organizados em quatro categorias: 1. Dos remédios que tomo aos que não sei: nas mãos dos profissionais de saúde; subdividida em duas subcategorias - A (in)atividade do paciente versus o tecnicismo profissional e A admissão e alta hospitalar como marcos na transição do cuidado; 2. A (des)continuidade da farmacoterapia; 3. Informação como estratégia de acesso aos medicamentos; 4. Acessibilidade possível. Os resultados mostram que os medicamentos ganham maior ou menor projeção nos cuidados ao paciente, além de serem uma das estratégias de atenção à saúde na hospitalização. Por isso, o acesso à farmacoterapia se torna heterogêneo, permeado de valores, relações e subjetividades, provocando sentimentos pautados no entendimento da necessidadedo uso dos medicamentos, do medo da reinternação, da indisponibilidade da farmacoterapia nas Unidades de Atenção Primária à Saúde e da incapacidade de compra de medicamentos pelo usuário. Apesar de programas que ofereçam abastecimento de medicamentos, o acesso a estes nos períodos pré e pós-internação se mostra fragilizado, constituindo-se um dos fatores fortalecedores do caminhar cíclico do paciente na rede de cuidados. As barreiras ao acesso referentes à informação se apresentam como um tema complexo, o que envolvediferentes processos de trabalhos permeados tanto pela relação profissional paciente como pelas interprofissionais. Entretanto, a informação é essencial para garantia do acesso à farmacoterapia, a fim de se evitarem comprometimentos de abastecimento, prescrição e disponibilidade dos medicamentos. Preparação da alta com antecedência, implantação de mecanismos de referenciamento ereconhecimento das subjetividades dos pacientes são algumas ações que contribuem para a garantia do acesso aos medicamentos. Conclui-se que a farmacoterapia é construída a partir das relações e vivências dos atores envolvidos e se revela importante tecnologia para o cuidado em todos os níveis de atenção à saúde.
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Wong, Chun-ming, and 黃俊銘. "Characterization of novel tumor suppressor genes, DLC-1 and DLC-2, in hepatocellular carcinoma." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B27768533.
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Graupner, Karola. "Untersuchungen zur Hochrateabscheidung harter DLC-Schichten." [S.l. : s.n.], 2005. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB11679790.
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Salgueiredo, Ermelinda da Conceição Portela. "Filmes de DLC para aplicações biotribológicas." Master's thesis, Universidade de Aveiro, 2007. http://hdl.handle.net/10773/2248.
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Mestrado em Engenharia Biomédica - BiomateriaisOs filmes de carbono amorfo tipo diamante (DLC) actuam como lubrificantes sólidos em muitas aplicações de desgaste incluindo os implantes articulares da anca e joelho. Entre estes, os filmes de carbono não-hidrogenado podem ser depositados pela técnica de deposição física em fase vapor (PVD) a baixas temperaturas (<325ºC). Estes filmes protectores são quimicamente inertes, possuem elevada dureza e baixo coeficiente de atrito contra polietileno de ultra alto peso molecular (UHMWPE) e outros biomateriais, aumentando assim a qualidade dos implantes articulares. Filmes de DLC foram depositados por sputtering DC em substratos à base de nitreto de silício (Si3N4 monolítico; compósitos Si3N4/TiN e Si3N4/bioglass) visando elevados níveis de adesão. A nanoestrutura do DLC, confirmada pela fraca intensidade da banda D do espectro Raman, combinada com o elevado conteúdo de ligações sp3, comprovado pelo desvio da banda G, levou a um valor de dureza de 16 GPa. Os filmes apresentam-se densos e homogéneos com um valor extremamente baixo de rugosidade (RMS=2.6 nm). Antes de ser implantado no corpo humano, um material tem de provar ser biocompatível. Antes da deposição de DLC, os substratos foram recobertos com uma camada de Si para promover a adesão. Após 35 dias de imersão em SBF, a observação SEM demonstrou que não ocorreu formação de camada apatítica na superfície. A análise química por ICP-AES mostrou que não houve variação na concentração dos iões Ca e P, e que não foram libertados elementos tóxicos na solução. A hidrofobicidade, tensão superficial e carga superficial deste biomaterial foram também avaliadas. A superfície apresentou um valor ligeiramente negativo de carga, como demonstrado pelo valor do potencial zeta de -35.0 ± 1.3 mV para pH=7.4 ± 0.2. A tensão superficial foi de 45.7 mN/m, apresentando uma componente dispersiva predominante da tensão superficial. Os resultados mostram que o revestimento de DLC é tendencialmente hidrofóbico. Os estudos com a linha celular de osteoblastos humanos MG63 não revelaram indícios de citotoxicidade. As células apresentaram morfologia normal e maior crescimento celular, quando comparadas com as placas standard de cultura, mostrando, no entanto, menor adesão celular. Para os ensaios biotribológicos, bolas e discos cerâmicos foram recobertos com filmes de DLC numa primeira etapa para ensaios de deslizamento a seco em movimento recíproco, com pares próprios. Um bias negativo foi aplicado ao compósito condutor Si3N4/TiN, resultando em valores de coeficiente de atrito extremamente baixos(μ=0.015). Numa segunda etapa, placas recobertas com DLC foram testadas contra bolas de UHMWPE. Os testes foram efectuados a seco e lubrificado (SBF). Os resultados preliminares mostram que o coeficiente de atrito mantém-se constante ao longo do ensaio, sem delaminação do DLC. Estes resultados favoráveis permitem recomendar o Si3N4 revestido com DLC como adequado para aplicações em próteses articulares. ABSTRACT: Diamond-like carbon (DLC) films act as solid-film lubricants in many wear resistant applications including articulated implants as hip and knee joints. Among these, non-hydrogenated amorphous carbon films can be grown by Physical Vapour Deposition (PVD) technique at low deposition temperatures (<325ºC). These protective coatings possess chemical inertness, high hardness and low friction coefficient against Ultra High Molecular Weight Polyethylene (UHMWPE) and other biomaterials, thereby improving the quality of articulated implants. In this study, the DLC films were deposited by DC magnetron sputtering over silicon nitride based substrates (bulk Si3N4; Si3N4/TiN and Si3N4/bioglass composites) aiming high adhesion levels. DLC nanostructure, confirmed by the weak intensity of the Raman spectra D band position, combined with significant sp3 content, as depicted by the G band downshift, lead to a hardness value of about 16 GPa. Films are dense and homogeneous in all the deposited area with an extremely low roughness of 2.6 nm (RMS). Before implantation in the human body, a material must prove to be biocompatible. Prior to the DLC deposition, the Si3N4 based ceramics were coated with a Si interlayer to promote adhesion. After 35 days of immersion in Simulated Body Fluid, SBF, the DLC surface showed no signs of apatite layer formation, as observed by SEM. Also, ICP-AES analysis confirmed no variation of the Ca and P ions concentration levels, and no toxic elements released into solution were detected. Hydrophobicity, surface tension and surface charge was also evaluated. The DLC surface is slightly negative charged, has shown by the zeta potential value of -35.0 ± 1.3 mV at pH=7.4 ± 0.2. The surface tension of the DLC coated samples was 45.7mN/m, presenting a dominant dispersive component of the surface tension. Results showed that the DLC coating is quite hydrophobic. Using the MG63 osteoblast-like cells, no evidence of citotoxicity was observed. Cells showed normal morphology and higher cell growth, compared to standard culture plates, although with low cell adhesion. For biotribological assessment, in a first stage Si3N4 ceramic balls and discs were coated with DLC films for self-mated reciprocating dry sliding tests. A negative bias voltage applied to a conductive Si3N4/TiN composite showed a remarkable improvement under the same tribological solicitation, presenting very low friction coefficient values (μ=0.015) during the full duration of the test. In a second stage, DLC-coated Si3N4 ceramics were tested against UHMWPE spheres using a reciprocating ball-on-flat set-up. The sliding occurred under dry and lubricated (SBF) conditions. Preliminary results showed that the friction coefficient is almost constant during the running-in period without delamination of the DLC coating. Based in these favourable results, the DLC-coated Si3N4 biomaterial seems adequate to be used for articular prosthesis development.
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Rudolf, Miroslav. "Depozice a analýza tenkých vrstev DLC." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228535.
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Diplomová práce nastiňuje problémy spojené s výrobou a analýzou tenkých vrstev DLC:H. Tyto vrstvy jsou ve středu zájmu mnoha vědeckých pracovníků již po několik desetiletí. V současné době existuje mnoho technik pro přípravu a analýzu. Příprava DLC vrstev má zásadní vliv na jejich vlastnosti a možnosti použití. Je zde mnoho kritérií jak vrstvy posuzovat. V této práci jsou studovány vlastnosti DLC:H vrstev připravených na substrát krystalického křemíku metodou RF-PECVD a následně jsou studovány mechanické, tribologické a optické vlastnosti. Jsou zde využity techniky jako XPS, Ramanova spektroskopie, reflektometrie, měření tvrdosti a adheze. Část práce se zabývá modelováním DLC z prvních principů. Pro tento účel je využito prvoprincipiálního programu Abinit který je šířen pod GPL. Je studována otázka přípravy vstupních dat s ohledem na konvergenci výsledků. Pozornost je také věnována výpočtu vibračních spekter ve středu Brillouinovy zóny ( bod) a celkové hustotě elektronových stavů clusteru DLC v supercele tvaru krychle. Tyto výsledky mohou být porovnány s experimentálně získanými daty z Ramanovy spektroskopie, respektive z XPS spektra valenčního pásu
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Marek, Mojmír. "Optimalizace distribučních cest - DLC Napajedla, a.s." Master's thesis, Vysoká škola ekonomická v Praze, 2008. http://www.nusl.cz/ntk/nusl-2882.
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Práce má za úkol nastínit možné směry optimalizace rozvrhu distribučních cest. Nástrojem je vhodně konstruovaný model, který se stane součástí aplikace. Aplikace vychází z programů MS Excel a LINGO. Zadání a následné řešení práce má podobu projektu. Předmětem není pouze vytvořit statický model (aplikaci). Práce také vychází z připomínek a požadavků zadavatele.
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Vengudusamy, Balasubramaniam. "Behaviour of lubricant additives on DLC coatings." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/11734.
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Non-ferrous surfaces such as diamond-like carbon (DLC) coatings are becoming potential candidates for automotive engine parts because of fuel economy gains that these surfaces offer by operating with very low friction. In recent years, a wide range of DLC coatings have been developed and it is important to understand their film-forming, friction reduction and wear resistance mechanisms under lubricated conditions. This aim of the work described in this thesis is to improve our understanding of the tribological behaviour of DLC coatings with different engine oil additives. The main focus of the thesis is to study a wide range of available DLC coating types with currently available and widely-used additives such as ZDDP, friction modifiers, MoDTC etc., in order to establish general rules of their tribological behaviour that will help lubricant manufacturers produce new oil formulations. The research shows that tribofilms are formed on all DLCs by most of the currently used additives and that the film thickness depends on various factors such as type of DLC coating, doping elements present in the coatings, concentration of hydrogen and tungsten present in the coatings and the counterpart. Hydrogen-free coatings (a-C and ta-C) give lower boundary friction compared to the other coatings whereas hydrogenated amorphous carbon (a-C:H) coatings give better wear resistance properties. Study of a-C:H:W coatings shows that the concentration of tungsten present in the coatings has a significant influence on wear resistance properties but negligible influence on the friction properties when additives are present. The steel/steel couple is known to form a thick ZDDP tribofilm. If one of the contact surfaces is coated with DLC, the tribofilm forming properties on the steel vary and, for some cases, the low boundary friction properties of DLCs are degraded.
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Silva, Cruz Ricardo Manuel Santos da. "TiBâ‚‚ ceramic and DLC multilayered PVD coatings." Thesis, Cranfield University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443347.
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Santos, da Silva Cruz Ricardo Manuel. "TiB2 ceramic and DLC multilayered PVD coatings." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/1863.
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Titanium diboride (TiB2) has been investigated as a potential candidate for several industrial applications, such as: cutting tools, electric devices, wear parts and many more fields of application. The main drawback of TiB2 is its brittle nature, which has limited its range of applications. Diamond-like Carbon (DLC) has been used in industrial applications, mainly for wear resistant parts. However, the application of DLC films has been limited by the level of internal stress accumulated during deposition. This thesis investigates the deposition of TiB2/DLC multilayer wear resistant coatings to overcome these limitations. The thesis focuses on the tribological effects caused by different deposition techniques on TiB2 ceramic used by the coatings industry today, in order to overcome the brittle nature of TiB2 and the lack of adhesion of DLC films. The multilayer coatings consisted of 25 bi-layers of TiB2/DLC. These TiB2/DLC coatings were fabricated, maintaining a constant composition wavelength (sum of two layers λ =200 nm) for an array of ceramic fractions ranging from 25% to 95% by volume using as substrates, tool steel AISI 1095 and powder metallurgy aluminium alloys, type 2618. The effect of the DLC content on the structure and performance (hardness, adhesion and wear) of the films was investigated. The bi-layer thickness influences the failure patterns observed in the scratch testing. These observations have been used to optimise the multilayered coating structure. Multilayer coatings have been manufactured to increase surface hardness and wear resistance as applied to a commercial powder metallurgy Al alloys (Al 2618) used in the automotive industry. Optimum coatings have found hardness values of 27.8 GPa, with a critical load of 20 N and a friction coefficient of 0.47. As a result of wear tests the multilayer with 10% of DLC was found to be best compromise between high hardness (23.8 GPa), good adhesion (critical load higher than 20 N), low friction and low wear rate.
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Rizzo, Vinícius Zacarias. "Estudo das propriedades ópticas e eletro-ópticas de filmes de carbono amorfo tipo diamante - DLC." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-10012011-143459/.
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Neste trabalho foram estudadas as características elétricas e ópticas de filmes de carbono tipo diamante (DLC Diamond-Like Carbon) depositados em um sistema de sputtering RF magnetron reativo em substratos de silício e vidro. Foram depositadas amostras em condições de processo distintas em cada tipo de substrato, sendo duas condições de pressão (5 mTorr e 10 mTorr) e para cada uma, quatro condições de potência de RF (100 W, 150 W, 200 W e 250 W). Os filmes depositados foram submetidos às seguintes técnicas de caracterização: perfilometria, para obtenção da espessura dos filmes e com isso a taxa de deposição; elipsometria, para obtenção do índice de refração; obtenção de curvas I-V, para obtenção da resistividade elétrica e cálculo do ganho de foto corrente, e da curva C-V de alta frequência, para cálculo da constante dielétrica dos filmes; transmitância óptica, para o cálculo do gap óptico através do método de Tauc; fotoluminescência, para determinar a emissão característica deste gap e espectroscopia de infravermelho por transformada de Fourier (FTIR), para se observar os tipos de ligações presentes no filme e calcular a relação entre hibridizações sp3 e sp2 entre átomos de carbono e hidrogênio no filme. As variações de algumas características dos filmes de DLC com os parâmetros de processo são apresentadas e comparadas. De acordo com as características dos filmes obtidos neste trabalho, com a variação dos parâmetros de processo, é possível sua aplicação como dielétrico de campo, por apresentarem baixa constante dielétrica, sendo o valor mais baixo obtido igual a 3,4; como material dielétrico de porta considerando os filmes com alta constante dielétrica, chegando a 6,7; como material para cobertura, devido à alta uniformidade (até 95%); e, o que foi mais explorado neste trabalho, para aplicações como sensores foto sensíveis, sendo que o maior ganho de foto corrente obtido foi 67 vezes. A possibilidade de produção de filmes de DLC com diferentes propriedades através da variação das condições de processo mostra sua versatilidade para uso em diferentes aplicações.In this work it was studied electrical and optical characteristics of diamond-like carbon (DLC) films deposited in a reactive RF magnetron sputtering system on silicon and glass substrates. Samples were deposited at different process conditions in each type of substrate at two pressure conditions (5 mTorr and 10 mTorr) and four conditions of RF power (100 W, 150 W, 200 W and 250 W). The DLC films were characterized by the following techniques: high step meter analysis, to obtain the thickness of the films and thus the deposition rate; Ellipsometry to obtain the refractive index; electrical characterization by the I-V curve, to obtain the resistivity and calculate the photo current gain, and high-frequency C-V curve, to calculate the dielectric constant of the films; optical transmittance, to calculate the optical gap by the Tauc method; photoluminescence analysis, to determine the characteristic emission of this gap; Fourier transform infrared spectroscopy (FTIR), to observe the different carbon-hydrogen bonds and calculate its sp3/sp2 hybridizations ratio. The way some characteristics of DLC films vary with the process parameters are presented and compared in this work. According to the characteristics of the DLC films obtained in this work, with the variation of the process parameters it is possible their application as low k dielectric insulators, because of its low dielectric constant, being the lowest obtained value 3.4; as dielectric gate material, reaching 6.7 in the films deposited in this work, as coating material due to its high uniformity (95%), and which was further explored in this work, for applications like photo-sensitive sensors, since it was obtained samples with photo current gain up to 65. The possibility of producing DLC films with different properties by varying process parameters shows its versatility for using in different applications.
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Tula, Sanchez Ana A. "Elucidation of the Mechanisms of Resistance and Sensitivity to Histone Deacetylase Inhibitor, PXD101, in Diffuse Large B-Cell Lymphoma (DLBCL)." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301692.
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Although curable in the majority of cases, Diffuse Large B-cell Lymphoma (DLBCL), the most prevalent Non-Hodgkin Lymphoma (NHL) throughout the world, is still fatal for 30-40% patients. This patient population could benefit from the addition of new drugs to the current DLBCL chemotherapy regimen. Histone deacetylase inhibitors (HDIs) are a promising group of drugs for the treatment of hematological malignancies. In the current study we tested the HDI PXD101 in a panel of the two most common DLBCL subtypes, GCB (germinal center) and ABC (activated B-cell like), ABC being the least curable subtype. Cell viability assays showed that PXD101 induces antiproliferative effects at submicromolar concentrations in DLBCL cell lines regardless of DLBCL subtype. Flow cytometry demonstrated that upon PXD101 treatment two GCB cell lines (DB and OCILY19) undergo G2M cell cycle arrest followed by apoptosis, while two GCB (SUDHL4 and SUDHL8) and one ABC (U2932) cell line undergo G1 arrest with little apoptosis. Further experiments demonstrated that upon PXD101 removal G1-arresting cells recover their normal proliferative state, while in G2M-arresting cells only 8h exposure to PXD101 is sufficient to induce considerable apoptosis. We classified as PXD101-resistant cell lines that re-enter the cell cycle after drug removal, and PXD101-sensitive cell lines that commit to apoptosis after short periods of drug exposure. Kinase assays established that upon PXD101 treatment G1 phase cyclin dependent kinase 2 (CDK2)-cyclin E complex activity significantly decreases in resistant but not in sensitive cells lines. Furthermore, pull-down assays revealed that CDK inhibitors (CDKIs) p21 and/or p27 in resistant, but not sensitive cell lines persistently bind the CDK2-cyclin E complex throughout PXD101 treatment, thereby explaining why resistant lines stop at the G1 phase. CDKIs induction by PXD101 was p53-independent. This is the first time that an in vitro model of sensitivity and resistance to HDIs in DLBCL is established. We have also performed preliminary genomic and proteomic analysis in DLBCL cell lines treated with PXD101. We anticipate that further analysis of the genomic response and the functional impact of protein acetylation induced by HDIs will offer additional insight into mechanisms of sensitivity and resistance to HDIs in DLBCL.
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Nagel, Daniel. "Identifikation und Charakterisierung niedermolekularer MALT1 Inhibitoren zur Therapie von ABC-DLBCL." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-165444.
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Kuitunen, H. (Hanne). "DLBCL, primary and secondary central nervous system involvement, treatment and prophylaxis." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526217154.
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Abstract Diffuse large B-cell lymphoma (DLBCL) is the most common type of Non-Hodgkin´s Lymphoma (NHL). The standard treatment for DLBCL is R-CHOP chemoimmunotherapy (rituximab, cyclophosphamide, vincristine, doxorubicin and prednisone). About one -third of patients have refractory disease or the lymphoma relapses. Prognosis after relapse of refractory disease is poor. Fitter and younger patients are recommended new intensive salvage chemotherapy followed by autologous stem cell transplantation. Central nervous system (CNS) relapse is the most feared complication with dismal prognosis in DLBCL. High dose methotrexate intravenously administered concurrently with R-CHOP treatment has shown to be most promising to prevent CNS relapses. Primary CNS lymphoma (PCNSL) is a rare aggressive lymphoma limited to the CNS and eyes. PCNSL is a chemo-and radiosensitive disease, but long-term response is rare since the blood brain barrier (BBB) limits access of many drugs to the CNS. BBB disruption (BBBD) is a treatment modality where the BBB is opened by hypertonic mannitol infusion. Administration of chemotherapeutics will achieve over ten-fold concentrations in the CNS and eradicate microscopic disease involvement. This study retrospectively analyses patients who treated as first line with Bonn/Bonn-like treatment (study I), with BBBD treatment followed by high-dose treatment/autologous stem cell transplantation (HDT/ASCT) in first- or second-line (study II) or those treated with primary R-CHOP or its derivatives with or without concurrent CNS-targeted treatment (study III). HD-MTX-based multichemotherapy is an effective induction treatment in CNS lymphoma, but long-lasting responses are rare. BBBD-treatment is well-tolerated and a promising method to attain high drug concentrations in the CNS to eradicate microscopic disease involvement in first- and second-line. CNS-prophylaxis with HD-MTX prevents CNS events in high risk DLBCL. PCNSL is agressive disease despite excellent primary response with HD-MTX based multichemotherapy. BBBD-treatment is a promising method to eradicate microscopic disease in the CNS and achieve a long-term response and cure rate. Fatal CNS relapses can be avoided using CNS-targeted treatmentTiivistelmä Diffuusi suurisoluinen B-solulymfooma (DLBCL) on yleisin non-Hodgkin lymfooma (NHL), jonka standardihoitona toimii R-CHOP (rituksimabi, syklofosfamidi, vinkristiini, doksorubisiini, prednisoloni). Noin kolmasosalla potilaista tautii etenee hoidosta huolimatta tai uusii hoidon päätyttyä. Relapoituneen tai refraktaarin taudin ennuste on huono. Hyväkuntoisilla ja nuoremmilla potilailla pyritään etenemään uuteen induktiohoitoon ja korkea-annoshoitoon autologisen kantasolusiirteen turvin. Keskushermostouusiutuma on huonoennusteisin DLBCL:n komplikaatio. Suuriannosmetotreksaattihoito liitettynä R-CHOP-hoitoon estää keskushermostouusiutumia. Primaari aivolymfooma (PCNSL) on harvinainen keskushermoston ja silmien alueelle rajautuva lymfooma. PCNSL on herkkä sytostaatti-ja sädehoidolle, mutta pitkäkestoisia vasteita nähdään harvoin. Veriaivoeste estää useimpien tehokkaiden sytostaattien pääsyn keskushermostoon. Veriaivoesteen aukaisuhoidossa veriaivoeste avataan hypertonisella mannitoli-infuusiolla. Toimenpiteen jälkeisellä sytostaatti-infuusiolla saavutetaan kymmenkertaiset lääkeainepitoisuudet keskushermostossa ja voidaan hoitaa mikroskooppista veriaivoesteen takana sijaitsevaa tautia. Väitöskirjatyön tutkimukset ovat retrospektiivisiä. Ensimmäisessä osatyössä analysoitiin PCNSL potilaat, jotka saivat ensilinjassa Bonnin tai Bonnin kaltaista hoitoa. Toisessa osatyössä potilaat hoidettiin joko ensi- tai toisessa linjassa BBBD-hoidolla, päättyen konsolidaatiohoitona annettavaan korkea-annoshoitoon autologisen kantasolusiirteen turvin. Kolmannessa osatyössä analysoitiin suuren aivouusiutumariskin potilaita, joko yhdessä tai ilman keskushermostoon suunnattua hoitoa samanaikaisesti R-CHOP-hoidon kanssa. Suuriannosmetotreksaatti-pohjainen yhdistelmäsolunsalpaajahoito on tehokas induktiohoito aivolymfoomassa pitkäkestoisten vasteiden ollessa harvinaisia. BBBD-hoito on hyvin siedetty ja lupaava hoitomuoto, jolla keskushermostossa voidaan saavuttaa suuret lääkeainepitoisuudet, jotka riittävät hoitamaan mikroskooppisen taudin sekä ensi että toisessa linjassa. Keskushermostoprofylaksia suuriannosmetotreksaatilla estää keskushermosto-uusiutumia suuren riskin DLBCL-potilailla. PCNSL on agressiivinen tauti huolimatta erinomaisista metotreksaattipohjaisilla hoidoilla saavutetuista ensilinjan vasteista. BBBD-hoito on lupaava keino eradikoida mikroskooppinen tauti keskushermostosta ja saavuttaa pitkäaikaisia hoitovasteita, sekä pysyvä paraneminen aivolymfoomassa. Suuriannosmetotreksaattia sisältävällä sytostaattihoidolla voidaan estää fataaleja aivorelapseja DLBCL:ssä
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Manhabosco, Taíse Matte. "Tribocorrosão da liga Ti6A14V, liga nitretada, Ti6A14V revestida por filmes Diamond-Like Carbon (DLC) e obtenção eletroquímica de filmes DLC." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/16202.
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Na presente tese realizou-se um estudo a respeito da tribocorrosão, isto é, atuação simultânea dos mecanismos de desgaste e corrosão, da liga Ti6Al4V, da mesma liga nitretada e dela recoberta por filmes DLC obtidos por PACVD em meio fisiológico simulado, considerando que ligas de titânio são amplamente empregadas em próteses sujeitas a esforços e os filmes a base de carbono apresentam grande potencial como biomaterial. Paralelamente foi estudada a obtenção de filmes DLC sobre titânio através de uma técnica pouco usual para aquisição destes revestimentos, a eletrodeposição. As amostras nitretadas foram caracterizadas ao MEV, por difração de raios X e microdureza. Os filmes produzidos por PACVD foram caracterizados ao MEV, espectroscopia Raman e a dureza, através de nanoidentação. Para os diferentes materiais, ensaios eletroquímicos, em solução fisiológica simulada, foram realizados a fim de verificar a resistência à corrosão e ensaios de desgaste a seco, para avaliar o comportamento tribológico.O comportamento frente à tribocorrosão, onde os mecanismos de desgaste e de corrosão atuaram simultaneamente, foram realizados para a liga, liga nitretada e filmes DLC depositados por PACVC. A liga Ti6Al4V mostrou-se bastante resistente à corrosão, apesar do pobre comportamento tribológico. Ensaios de tribocorrosão confirmaram a boa resistência à corrosão da liga, mesmo com os mecanismos de desgaste e corrosão atuando simultaneamente. A camada de nitretos, obtida do processo de nitretação, apresentou melhora no comportamento tribológico, frente à corrosão e tribocorrosão. Filmes DLC apresentaram excelente resistência ao desgaste e à corrosão quando ensaios foram realizados separadamente. Ensaios de tribocorrosão mostraram a falha prematura do filme quando da atuação simultânea dos mecanismos. O estudo paralelo a respeito da eletrodeposição confirmou a possibilidade de obtenção de filmes DLC através desta técnica, a temperatura ambiente. Os filmes foram avaliados por espectroscopia Raman e testados quanto à resistência à corrosão e ao desgaste. A dureza dos filmes foi avaliada por nanoidentação e a morfologia, verificada ao MEV e AFM. Filmes obtidos a partir de acetonitrila apresentaram uma melhora na resistência à corrosão comparado ao titânio puro, enquanto que os filmes obtidos de DMF comportaram-se similarmente ao titânio, possivelmente pela presença de trincas nanométricas. Relativo à resistência ao desgaste, os filmes obtidos de DMF, mostraram-se mais eficazes.In the present work it was performed a study about tribocorrosion performance of Ti6Al4V bare alloy and the same alloy Ti6Al4V nitrided or even recovered by DLC films in simulated physiologic environment considering the extensive application of this alloy in loaded implants and the possibility to use DLC films as a biomaterial. At the same time, it was studied the electrodepositon of DLC films onto titanium. Nitride samples were characterized by SEM (scanning electron microscopy), X ray diffraction and microhardness. The DLC films obtained by PACVC technique were characterized by SEM, Raman spectroscopy and nanoidentation. Corrosion experiments were conducted in simulated physiologic environment. The tribologic behavior was evaluated by dry wear tests. Tribocorrosion behavior, with corrosion and wear mechanisms acting simultaneously, was evaluated for the bare alloy, nitrided alloy and DLC films obtained by PACVD technique. The alloy is quite resistant to corrosion despite its poor tribological behavior. Tribocorrosion tests confirmed the good resistance to corrosion even when the degradation mechanisms of wear and corrosion act simultaneously. The nitride compound layer improved the tribological, corrosion and tribocorrosion behavior. DLC films presented high performance to either corrosion or wear mechanisms, however a catastrophic failure of the coating was observed in tribocorrosion tests. A parallel study confirmed the possibility of obtaining DLC films by a electrodeposition technique at room temperature. Raman measurements, corrosion and wear tests were performed. The hardness of the films was evaluated by nanoidentation. Films obtained from acetonitrile present a better corrosion resistance with respect to pure titanium. Films obtained from DMF presented a similar corrosion behavior as presented by titanium probably due the presence of some detected nanocracks. The films obtained from DMF presented a better tribological behavior.
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Boudesco, Christophe. "Expression et rôle d’HSP110 dans le lymphome B diffus à grandes cellules de type activé ou ABC-DLBCL." Thesis, Bourgogne Franche-Comté, 2018. http://www.theses.fr/2018UBFCI014.
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Les protéines de chocs thermiques (HSP) sont des protéines très conservées au cours de l’évolution des espèces. Ce sont des chaperons moléculaires impliqués dans le repliement des protéines nouvellement synthétisée ou dénaturées. Les HSP sont fortement exprimées dans les cellules cancéreuses, où elles contribuent à la résistance à l’apoptose et aux chimiothérapies. Parmi les HSP, HSP110 est jusqu’à présent peu étudiée. Cependant, HSP110 a été récemment associée au lymphome diffus à grandes cellules B (DLBCL). Le DLBCL est le syndrome lympho-prolifératif agressif le plus fréquent chez l’adulte (30% des lymphomes non-Hodgkinien). Il existe trois principaux sous-type de DLBCL : le type B activé (ABC-DLBCL), le type centre germinatif (GC-DLBCL) et le type lymphome primaire du médiastin (PMBL). La forme activée est celle associée au plus mauvais pronostic clinique. Bien que les thérapies classiques de chimiothérapies associées aux anti-CD20 aient permis d’augmenter le pronostic de survie des patients souffrant de l’ABC-DLBCL, nombreux sont ceux qui développent des résistances ou qui ne répondent pas aux traitements. L’identification de nouvelles cibles thérapeutiques est donc nécessaire.Mes travaux présentent un rôle de HSP110 dans l’activité d’une voie oncogénique du lymphome ABC-DLBCL. En effet, ces travaux démontrent une forte expression d’HSP110 dans les échantillons patients ABC-DLBCL. De plus, ces travaux in vitro sur des lignées ABC-DLBCL montrent une interconnexion entre HSP110 et Myd88 L265P, protéine mutée responsable de l’activation de la voie NF-kB. HSP110 stabilise l’oncogène Myd88 L265P, et participe à l’amplification de la voie NFkB dans le lymphome ABC, voie responsable de la survie et de la prolifération des cellules ABC-DLBCL.Par le biais d’une collaboration, nous avons pu obtenir récemment des inhibiteurs de HSP110. Ainsi, mon travail à également consisté aux criblages in vitro de ces inhibiteurs pour évaluer leur capacité d’inhibition de HSP110. Deux composés ont alors été identifiés comme candidats inhibiteurs d’HSP110. Je me suis ensuite intéressé à l’utilisation de ces inhibiteurs in vitro dans l’ABC-DLBCL. Mes résultats tendent à montrer que ces inhibiteurs ont une action similaire à ceux observés lors de l’inhibition de HSP110 par siRNA ou shRNA.Mes travaux de thèse présente donc HSP110 comme une cible moléculaire potentielle de l’ABC DLBCLHeat shock proteins (HSPs) are highly conserved protein across species, and are expressed in all cell type. HSPs are molecular chaperones involved in the folding of newly synthesized or denaturated proteins. HSPs are overexpressed in cancer cells, where they contribute to cancer resistance to chemotherapies. Among HSPs, roles and functions of HSP110 are less described. Interestingly, HSP110 was recently associated with lymphoma aggressiveness in Diffuse Large B Cell Lymphoma (DLBCL). DLBCL is the most lymphoproliferative disease diagnosed in adult (30% of Non-Hodgkin Lymphoma). Three main subtypes of DLBCL are described: Activated-B-Cell lymphoma (ABC-DLBCL), Germinal Center lymphoma (GC-DLBCL), and Primary Mediastinal B Lymphoma (PMBL). ABC-DLBCL is the most aggressive form associated with a poor prognosis. Even if R-CHOP therapies had improve patient’s survival over the last decades, most of patients experiences relapses or treatment resistances. New molecular target are now necessary to treat efficiently these subtypes.My PhD work has highlighted the role of HSP110 in the NFkB signaling pathway, which is an oncogenic pathway in ABC-DLBCL. First, we show that HSP110 is overexpressed in ABC-DLBCL patient sample. We also show an interaction between HSP110 and Myd88 L265P, that is an oncogenic protein responsible for NFkB pathway activation. Consequently, HSP110 stabilizes Myd88 L265P, leading to a sustain NFkB pathway activation in lymphoma cells, and promoting ABC-DLBCL cell survival and proliferation.Finally, our team recently characterized the first known HSP110 inhibitors. I took the opportunity to test these putative inhibitors in my study. My results suggest that these compounds have similar effects than siRNA or shRNA inhibition of HSP110 on ABC-DLBCL survival. This result provide a ground for future in vivo testing of chemical inhibitors of HSP110.In conclusion, my work highlight HSP110 as a potential therapeutic target in ABC-DLBCL
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Renman, Viktor. "Tribological testing of DLC coatings for automotive applications." Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-177355.
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In this work, the friction and wear behavior of three DLC coatings was evaluated in various conventional and alternative fuels as well as in commercially available formulated engine oils and additive-free synthetic oil. The first DLC has a thin top-coating of hydrogenated amorphous carbon (a-C:H), the second consists of Si-doped DLC (a-C:H:Si) and the third is a W-doped multilayered structure of a-C:H and a-C:H:W. The tribological tests were performed using a ball-on-flat reciprocating rig at low contact pressures. Methods such as white light interferometry (VSI), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), Raman spectroscopy, transmission electron spectroscopy (TEM) and electron spectroscopy for chemical analysis (ESCA/XPS) were used for analyzing and characterizing the coatings and counter surfaces in an effort to gain an understanding of the tribological mechanisms involved.
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Crawford, Richard I. "Novel routes to DLC and related wear coatings." Thesis, University of Ulster, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284837.
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Young, Sheng-Yu. "DLC thin film assisted zinc oxide nanowires growth." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8613.
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Thesis (M.S.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Materials Science and Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Hlatshwayo, Lerato. "Investigation of protein biomarkers in HIV positive and HIV negative associated DLBCL." Master's thesis, Faculty of Health Sciences, 2020. http://hdl.handle.net/11427/32681.
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Introduction: Diffused large B-cell lymphomas (DLBCL) is the most common aggressive nonHodgkin lymphoma (NHL) worldwide, constituting up to 40% of all cases globally. The incidence of HIV-associated lymphoma has decreased since the introduction of combination antiretroviral therapy (cART) in the mid-1990s. However, NHL, especially DLBCL remains the most common cause of morbidity and mortality among people living with HIV/AIDS, especially in sub-Saharan Africa where 70% of the global HIV/AIDS population reside. Gene expression profiles (GEP) identified based on the cell of origin (COO) two distinct DLBCL subtypes; germinal-centre B-cell-like (GCB) and activated B-cell-like (ABC) DLBCL. These subtypes differ in their genetic abnormalities and response to treatment regimens. Aim: We aimed to investigate in detail, protein distribution profile from FFPE tissue in HIV and non-HIV related DLBCL subtypes. Methods: FFPE DLBCL lymph node tissue samples from HIV and non-HIV related DLBCL were subjected to MALDI-imaging, in order to get the spatial distribution of proteins in DLBCL tissue. Proteins were extracted from tissue samples and subjected to liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) to identify proteins present in FFPE DLBCL tissue. The protein profiles from the above-mentioned samples were compared and characterized by cancer pathways. Results: This study had 12 DLBCL cases and 2 human tonsil controls diagnosed from 2009- 2011. These cases were retrieved using the NHLS database. The overall age of DLBCL patients by the time they were diagnosed ranged from 18 to 73 years, with a median age of 48 years. MALDI-IMS peak detection function identified 1466 different m/z values from both the HIV negative and HIV positive DLBCL cases. There were only 50 exclusive m/z values that distinguished the DLBCL subtypes, Using LC-MS/MS we identified a total of 88 proteins, by comparing these proteins, we observed 6 differentially expressed among the DLBCL subtypes and controls Fructose-bisphosphate aldolase C was the only significantly differentially expressed proteins between HIV negative ABC DLBCL and HIV positive ABC DLBCL subtype (p value=1,47738). 10 Conclusion: Using proteomic techniques, we identified and visualized differentially expressed protein in DLBCL subtypes and controls. The majority of these proteins belonged to glycolysis, ATP synthesis, and cellular movement.
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Dubois, Sonia. "Caractérisation de nouveaux régulateurs de l'activation lymphocytaire et de la lymphomagenèse." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA11T033/document.
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Le lymphome diffus à grandes cellules B (DLBCL, Diffuse Large B-Cell Lymphoma) constitue le lymphome non Hodgkinien le plus fréquemment diagnostiqué. Les DLBCL sont composés principalement de deux sous groupes : l’entité nommée ABC (Activated B Cell-like) qui est la plus agressive, avec un taux de survie de 30% après traitement, et l’entité GCB (Germinal-Center B Cell). Contrairement aux GCB DLBCL, les ABC DLBCL se caractérisent par une signature génique similaire aux lymphocytes B activés par leur récepteur antigénique (BCR, B Cell Receptor) à cause de l'accumulation de mutations génétiques. Ceci a pour conséquence une activation constitutive du facteur de transcription NF-κB pour laquelle les lymphomes ABC DLBCL ont développé une profonde addiction. Toutefois, la nature pléiotrope de NF-κB rend son ciblage thérapeutique inenvisageable. Mon projet de thèse visait à caractériser de nouveaux régulateurs de la voie d’activation du facteur NF-κB par les récepteurs antigéniques en condition physiologique et pathologique. Dans un premier temps, grâce à un crible protéomique par spectrométrie de masse, nous avons identifié un complexe ternaire nommé LUBAC (Linear Ubiquitin Chain Assembly Complex) comme un acteur majeur de l’activation de NF-κB par le TCR et le BCR, et de la survie des lymphomes ABC DLBCL. Dans un second temps, le crible d’une librairie de mille deux cents molécules chimiques nous a permis d’isoler un composé sélectivement toxique in vitro pour les lymphomes ABC DLBCL. Nous montrons que ce composé entraine la mort apoptotique des ABC DLBCL sans toutefois affecter la signalisation NF-κB. Un tel composé pourrait, dans le futur, être utilisé comme une nouvelle molécule thérapeutique pour le traitement du lymphome ABC DLBCLThe diffuse large B cell lymphoma (DLBCL) is the most common non Hodgkinien lymphoma. Two main different entities composed the DLBCL : the Activated B Cell-like subtype (ABC DLBCL) witch is the most aggressive and associated with a poor survival prognostic, and the Germinal-Center B Cell subtype (GCB DLBCL). Unlike the GCB DLBCL, ABC DLBCL are characterized by a genetic signature similar to activated B lymphocytes stimulated by their antigen receptor (BCR, B cell receptor) which results from mutations accumulation. As a consequence, ABC DLBCL survival and proliferation requires the constitutive activation of NF-κB transcription factors. Because NF-κB has pleiotropic effect on different tissues, strategies aiming at targeting NF-κB heterodimers might have deleterious consequences on an organism.My project focuses on identifying new modulators involved in antigen receptor mediated NF-κB activation in physiological and pathological condition.We first performed a mass spectrometry analysis and identified the LUBAC (Linear Ubiquitin Chain Assembly Complex) as a new regulator of antigen receptor mediated a NF-κB ctivation and ABC DLBCL survival. Then, we screened a library of one thousand two hundred chemical compounds on DLBCL viability and identified one compound selectively toxic in vitro for the ABC DLBCL subtype. This compound induced ABC DLBCL apoptosis without affected NF-κB signaling. In the future, this compound could be used as a new therapeutic compound for ABC DLBCL
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Stanley, Illana Allake. "Metabolic Heterogeneity in Molecular Subsets of Diffuse Large B-cell Lymphoma." Thesis, Harvard University, 2014. http://nrs.harvard.edu/urn-3:HUL.InstRepos:13069713.
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Cells adapt their metabolism to satisfy changing bioenergetic and biosynthetic needs. Investigation of metabolic reprogramming in cancer has provided insight into the metabolic control of proliferation and survival. While the predominant focus of this field has been aerobic glycolysis (the Warburg effect), increasing evidence points to a complex landscape of tumor metabolic circuitries beyond aerobic glycolysis, including varied degrees of mitochondrial contribution to tumor metabolism.
To investigate alternative metabolic programs compatible with tumor growth, we turned to Diffuse Large B-cell Lymphoma (DLBCL), a highly heterogeneous disease encompassing discrete clusters or subtypes defined by tumor-intrinsic genetic distinctions. In one classification scheme, a B-cell receptor (BCR)/proliferation cluster identified BCR-dependent DLBCLs with elevated expression of BCR signaling components. A second subset, OxPhos-DLBCL, displayed increased expression of mitochondrial oxidative phosphorylation genes, and was insensitive to BCR inhibition. However, the functional attributes of OxPhos-DLBCLs and the nature of their BCR-independent survival were unknown.
Upon integrative analyses of DLBCL subtypes, we uncovered quantitative proteome- and metabolome-level signatures associated with differences in nutrient and energy metabolism. Specifically, BCR-DLBCLs have greater glycolytic flux typical of the Warburg phenotype. Unlike BCR-DLBCLs, OxPhos-DLBCLs channel the majority of glucose-derived pyruvate into mitochondria, display elevated mitochondrial electron transport chain (ETC) activity, ATP production, and fatty acid oxidation (FAO). Importantly, these metabolic distinctions are associated with subtype-selective survival mechanisms. Moreover, acute inhibition of BCR signaling in BCR-DLBCLs increased their FAO capacity, thus revealing a reciprocal relationship between BCR and FAO.
Further dissection of mitochondrial function in OxPhos-DLBCLs indicates that increased mitochondrial metabolism is integrated with at least two homeostatic mechanisms that help maintain ETC activity and FAO capacity. In particular, OxPhos-DLBCLs harbor robust protein-level enrichment of mitochondrial translation factors required for the synthesis of mitochondrial-DNA-encoded ETC subunits. Inhibition of the mitochondrial translation pathway is selectively toxic to OxPhos-DLBCLs. A second mitochondrial homeostatic pathway, mitochondrial network dynamics, also proved relevant to OxPhos-DLBCLs. Compared to BCR-DLBCLs, OxPhos-DLBCLs display a fragmented mitochondrial network that supports their FAO capacity. Overall, these findings demonstrate previously unappreciated metabolic heterogeneity in molecular subsets of DLBCL and uncover BCR-independent survival mechanisms linked to mitochondrial FAO, protein translation, and network architecture.
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Pfennig, Sabrina [Verfasser], Milton T. [Akademischer Betreuer] Stubbs, Ralph P. [Akademischer Betreuer] Golbik, and Norbert [Akademischer Betreuer] Sträter. "Strukturelle und thermodynamische Charakterisierung der DltA-DltC-Interaktion und kinetische Analyse der DltA katalysierten D-Alanylierung des DltC / Sabrina Pfennig. Betreuer: Milton T. Stubbs ; Ralph P. Golbik ; Norbert Sträter." Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2015. http://d-nb.info/1073150704/34.
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Gotzmann, Gaby. "Elektronenstrahlmodifizierung von diamantähnlichen Kohlenstoffschichten zur biofunktionalen Beschichtung von Implantatmaterialien." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-232694.
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Die vorliegende Arbeit befasst sich mit der Modifizierung von Beschichtungen auf Basis von diamantähnlichem Kohlenstoff (DLC). Die Modifizierung erfolgte mittels Elektronenstrahl (eBeam) und sollte der Oberflächenfunktionalisierung durch die Steuerung der Zelladhäsion dienen. Das Anwendungsfeld der modifizierten DLC-Schichten findet sich im biomedizinischen Bereich. Als Anwendungsbeispiel wurden Aktoren aus Formgedächtnislegierung (FGL) herangezogen. Diese sollen in Hüftendoprothesen genutzt werden. Ihre Aufgabe ist es, bei Implantatlockerung eine Wiederverankerung im Knochen, ohne äußeren Eingriff zu ermöglichen. Die Aktoren stellen an eine Beschichtung besondere Herausforderungen hinsichtlich Schichtstabilität und -flexibilität, Zelladhäsion sowie Barrierefunktion. Im Folgenden werden die untersuchten Schwerpunkte mit Bezug auf dieses Anwendungsbeispiel zusammenfassend dargestellt.
Im ersten Abschnitt der vorliegenden Arbeit wurden vier Abscheidemethoden für DLC-Beschichtungen verglichen: die plasmaaktivierte chemische Gasphasenabscheidung (PA CVD), das Magnetronsputtern (PVD-Spu), und die Lichtbogenverdampfung ungefiltert und -gefiltert (PVD-Arc bzw. PVD-Arcfil). Aus diesen Abscheidemethoden sollte eine für das medizintechnische Einsatzgebiet geeignete Methode zur DLC-Abscheidung ausgewählt werden. Dafür wurden folgende Kriterien untersucht: Schichtmorphologie und stabilität, Biokompatibilität und die Möglichkeit zur Modifizierung mittels eBeam. Es zeigte sich, dass mittels Magnetronsputtern homogene DLC-Schichten abgeschieden werden können. Diese Beschichtungen zeigen im Vergleich zu den Beschichtungen der anderen Abscheideverfahren die beste Biokompatibilität. Die Modifizierung der Schichten mittels eBeam ermöglicht eine gezielte Verringerung der Zelladhäsion auf den Oberflächen, ohne zelltoxische Nebenwirkungen. Mit diesem Resultat wird die ausgewählte Beschichtung den Funktionsansprüchen des Anwendungsbeispiels gerecht. Als Anwendungsbeispiel wurden Aktoren einer intelligenten Hüftendoprothese herangezogen. Die Aktoren bestehen aus FGL-Material und sollen im Anwendungsfall eine intrakorporale Verformung durchführen. Die DLC-Beschichtung soll den Austritt von toxischen Nickelionen aus diesem Material verringern. Daher ist die Stabilität der DLC-Schichten auf den Aktoren für den zielgerechten Einsatz von grundlegender Bedeutung. Die Formflexibilität von DLC-Schichten ist aus der Literatur bekannt, womit sie eine geeignete Barrierebeschichtung für verformbare Bauteile darstellen, ohne dabei die Funktion des Substratmaterials zu beeinträchtigen. Grundlage für diese Formflexibilität stellen eine gute Schichthaftung und Langzeitstabilität dar. Auch an dieser Stelle zeigten die mittels Magnetronsputtern abgeschiedenen DLC-Schichten sehr gute Ergebnisse. Selbst die Beanspruchung durch wiederholte Desinfektion und Sterilisation führte bei dieser Beschichtung zu keiner Veränderung. Im Anwendungsbeispiel Hüftendoprothese kann es an der Implantat-Knochen-Schnittstelle zu Mikrobewegungen kommen. Durch die im Vergleich zu den anderen Beschichtungen sehr guten Ergebnisse der PVD-Spu-Schichten bei der tribologischen Charakterisierung, stellen diese Schichten eine für das Anwendungsbeispiel geeignete Beschichtung dar. Ein geringer Reibwert gewährleistet dabei eine ungestörte Gewebsintegration. Das Magnetronsputtern wurde basierend auf diesen Ergebnissen als geeignete Abscheidemethode für die DLC-Beschichtung von Implantatmaterialien ausgewählt.
Im zweiten Abschnitt der Arbeit wurden die Modifizierung der Beschichtung, die Reaktion im biologischen Kontakt und die Barrierefunktion der Schichten bewertet. Durch die eBeam-Modifizierung der DLC-Beschichtung wird eine Hydrophilierung erzielt, die mit einer signifikanten Verringerung der Zellzahl auf der Oberfläche verbunden ist. Nach Beurteilung der Schichtmorphologie von unbehandelten und modifizierten DLC-Oberflächen konnte ausgeschlossen werden, dass die Hydrophilierung auf Veränderungen der Oberflächenmorphologie zurück zu führen ist. Vielmehr wurden chemisch-energetische Veränderungen als Ursache identifiziert, wobei die indirekte eBeam-Wirkung während der Modifizierung zum Tragen kommt. Die Intensität der Hydrophilierung ist dosisabhängig und zeigt eine Art Sättigungsverhalten ab 500 kGy. Es konnte gezeigt werden, dass durch die Modifizierung der Anteil stickstoff- und sauerstoffhaltiger Funktionalitäten auf der DLC-Oberfläche zunimmt. Die Verringerung der Zellzahl, welche ebenfalls eine Art Sättigung bei 500 kGy zeigt, steht über die Proteinadhäsion mit diesen Veränderungen in direktem Zusammenhang. In Korrelation mit der Literatur scheint es durch die Zunahme der sauerstoffhaltigen Funktionalitäten zu einer veränderten Proteinadhäsion zu kommen. Dabei wird die Proteinkonformation verändert, was die anschließende Zelladhäsion verringert. Mittels eBeam können sehr feine Strukturen bis in den Mikrometerbereich modifiziert werden, was bedeutet, dass damit die Zelladhäsion in den aneinander angrenzenden Bereichen des Aktors gezielt eingestellt werden kann. Damit wird die DLC-Beschichtung mit dieser Modifizierung den Funktionsansprüchen des Aktorbauteiles gerecht. Die Analyse der Langzeitstabilität zeigte, dass die Modifizierung sowohl an Luft als auch in phosphatgepufferter Salzlösung (PBS) über einen Zeitraum von mindestens zwei Monaten stabil ist. Somit kann für das Anwendungsbeispiel die Modifizierung bereits langfristig vor dem Einsatz eines Implantates erfolgen. Bisher wurden derartige Modifizierungen hauptsächlich mittels Plasmabehandlung durchgeführt. Im Gegensatz zur vorliegenden Arbeit können damit jedoch keine zeitlich stabilen Effekte erzielt werden. Weitere Nachteile der Plasmamethoden ergeben sich durch Materialveränderungen und verhältnismäßig lange Prozesszeiten. Weiterhin wird laut Literatur bei der Plasmabehandlung von DLC-Oberflächen eine Steigerung der Zelladhäsion erzielt. In der vorliegenden Arbeit besteht das Ziel jedoch in der Verringerung der Zelladhäsion, wodurch sich auch unter diesem Aspekt die eBeam-Modifizierung gegenüber der Plasmamodifizierung als vorteilhaft erweist.
Zusätzlich wurde neben der Langzeitstabilität für die eBeam-modifizierten DLC-Beschichtungen auch eine Stabilität gegenüber chemisch-mechanischer Reinigung mit anschließender Dampfsterilisation belegt. Da jedoch die FGL-Aktoren im Anwendungsbeispiel durch thermischen Energieeintrag aktiviert werden, könnte die herkömmliche Anwendung der Dampfsterilisation ein Problem darstellen. Auch dafür bietet die eBeam-Behandlung als alternative Sterilisationsmethode einen Lösungsansatz. Mit einer Sterilisationsdosis von lediglich 25 kGy ist die Anwendung des eBeams sowohl zur Sterilisation von unbehandelten als auch modifizierten DLC-Oberflächen möglich, ohne deren Eigenschaften oder die des beschichteten Substrates zu beeinflussen. Die eBeam-Modifizierung der DLC-Oberflächen bietet basierend auf den vorliegenden Ergebnissen eine Möglichkeit zur Steuerung der Zelladhäsion, da in den modifizierten Bereichen eine signifikante Verringerung der Zellzahl erzielt wird. Eine Verringerung der Zellzahl ist für die beweglichen Bereiche der FGL-Aktoren besonders wichtig, um deren Funktion zu gewährleisten (s. Abbildung 1). Für die modifizierten Schichten werden dabei keine Beeinträchtigung der Zellvitalität oder Veränderungen der Phasen des Zellzyklus festgestellt. Weiterhin ist belegt, dass von diesen Beschichtungen kein erhöhtes Entzündungspotential ausgeht, was den uneingeschränkten Einsatz der modifizierten DLC-Beschichtungen im biomedizinischen Bereich ermöglicht. Die unbehandelten DLC-Oberflächen hingegen sollen im Anwendungsbeispiel eine schnelle Implantatintegration gewährleisten. Auch diesem Anspruch wird die Beschichtung gerecht, da die osteogene Differenzierung humaner mesenchymaler Stammzellen auf diesen Oberflächen uneingeschränkt verläuft. Die Analyse des Calciumgehaltes als späten Differenzierungsmarker lässt sogar auf einen stimulierenden Effekt durch die Schichten schließen. Folglich kann für den Anwendungsfall der Hüftendoprothese eine beschleunigte Osseointegration erwartet werden. Die größte Herausforderung für die DLC-Beschichtungen bestand in der Verringerung des Nickelaustrittes aus dem FGL-Material. Die Ergebnisse der Extraktionsversuche belegen, dass aus unbeschichteten FGL Nickelionen austreten und die Stoffwechselaktivität von Osteoblasten beeinflussen. Auf DLC-beschichteten Proben hingegen kann kein messbarer Austritt von Nickelionen festgestellt werden. Im Direktkontakt mit humanen Osteoblasten zeigt sich auf den unbeschichteten FGL eine unnatürliche Zellmorphologie, was auf den Nickelaustritt zurückgeführt werden kann. Dahingegen erscheinen die Zellen auf den DLC-beschichteten Oberflächen in vitaler Morphologie. Diese Ergebnisse demonstrieren die Wirksamkeit der DLC-Beschichtung als Barriere gegenüber dem Austritt von Nickelionen.
Zusammenfassend wird festgestellt, dass das Magnetronsputtern die Abscheidung von DLC-Schichten ermöglicht, die dem Anwendungsbeispiel Hüftendoprothese mit FGL-Aktor sowohl hinsichtlich Barrierefunktion als auch Biokompatibilität gerecht werden. Die Modifizierung mittels eBeam gewährleistet dabei die gezielte Steuerung der Zellzahl, wodurch die DLC-Beschichtungen auch die biofunktionalen Ansprüche des Anwendungsbeispiels bedienen. DLC-Beschichtungen weisen aufgrund ihrer großen Variabilität hinsichtlich Materialeigenschaften und der sehr guten Biokompatibilität ein breites Spektrum für biomedizinische Anwendungen auf. Die eBeam-Modifizierung der Beschichtungen eröffnet aufgrund ihrer Langzeitstabilität darüber hinaus weitere Einsatzfelder. Vor allem die Option einer partiellen Oberflächenmodifizierung ermöglicht es, variierenden Funktionsansprüchen zahlreicher Anwendungen gerecht zu werden und die im Rahmen der vorliegenden Arbeit gewonnen Erkenntnisse auf weitere Einsatzfelder zu übertragen.
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Wu, Jianhui. "Tribological behavior of WC-DLC-WS2 (WCS) nanocomposite coatings." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1094675462.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xix, 188 p.; also includes graphics. Includes bibliographical references (p. 179-188).
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Salvaro, Diego Berti. "Avaliação tribológica de DLC em regime de lubrificação mista." reponame:Repositório Institucional da UFSC, 2015. https://repositorio.ufsc.br/xmlui/handle/123456789/159648.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Ciência e Engenharia de Materiais, Florianópolis, 2015.Made available in DSpace on 2016-03-01T04:04:20Z (GMT). No. of bitstreams: 1 337499.pdf: 3616668 bytes, checksum: 5d5aef3c5b1c288568c3f8c612d16b27 (MD5) Previous issue date: 2015
A lubrificação fluida é um ramo da tribologia bastante desenvolvido devido às inúmeras aplicações nos mais diferentes segmentos industriais. O regime de lubrificação limite é responsável por significativa parcela de perdas por atrito e desgaste em sistemas lubrificados. Por esse motivo, os óleos lubrificantes possuem aditivos em suas formulações para que os mesmos reajam com as superfícies em contato e movimento relativo para gerar tribofilmes antidesgaste na região do contato. Os aditivos possuem em sua composição química elementos como fósforo e enxofre que em grandes concentrações podem trazer danos à saúde humana e ao meio ambiente. Consequentemente, legislações cada vez mais severas pressionam para redução, ou até mesmo eliminação desses aditivos nos lubrificantes. Os DLC são revestimentos a base de carbono amorfo que possuem além de alta dureza e estabilidade eletroquímica, propriedades autolubrificantes. Portanto, os DLC possuem grande potencial para redução dos aditivos nos óleos, principalmente em regimes de lubrificação limite. Diversos estudos já foram conduzidos nesse sentido, contudo, a grande maioria deles utiliza óleos e aditivos da indústria automotiva de elevada viscosidade. É exatamente nesse ponto que o presente trabalho exerce grande avanço, pois avaliou o desempenho tribológico do DLC (a-C:H) em um cenário típico da indústria de compressores herméticos para refrigeração, ou seja, com lubrificante de baixa viscosidade (4,2mm²/s a 40°C). Para atingir os objetivos foram realizados testes com a configuração cilindro-plano (contato em linha), onde um cilindro desliza (movimento alternativo) sem rolar sobre uma superfície plana durante tempo e força normal pré-determinados. Os testes foram realizados a seco e repetidos com a presença do óleo. Foram analisadas as marcas de desgaste via microscopia óptica e eletrônica, interferometria óptica de luz branca, espectroscopia Raman e espectroscopia de energia dispersiva. Os resultados mostraram que o comportamento tribológico dos pares testados a seco são governados por tribocamadas, que por sua vez são formadas por partículas de desgaste oxidadas sujeitas a ação do contato. Além disso, foi encontrado carbono na forma de grafite nessas tribocamadas. A presença do óleo reduz o coeficiente de atrito dos pares testados e o aditivo BTP reage com as superfícies metálicas para formar tribocamadas antidesgaste. Mecanismos dúcteis atuam no desgaste do ferro fundido enquanto que no DLC ocorre degradação por mecanismo frágil. A sinergia entre tribocamadas provenientes da reação do aditivo com superfícies metálicas e a possível grafitização do DLC governam o desempenho tribológico dos pares envolvendo DLC e ferro fundido cinzento.
Abstract : Liquid lubrication is a well-established technological branch due to several applications in different industrial segments. Boundary regime lubrication is responsible for a significant amount of frictional losses and wear in lubricated systems. For this reason, lubricating oils are usually formulated with different types of additives in order to form protective antiwear tribofilms on the real contact regions. Additives are composed of elements like phosphorus and sulfur that might be hazardous to human health and the environment when added in high concentrations. Therefore, severe regulations demand the reduction or even removal of such additives from lubricants. Diamond-like carbons (DLC) are a family of coatings containing high amounts of amorphous carbon that possess high hardness, chemical stability and self-lubricating properties. For this reason, DLCs have great potential in reducing the usage of additives in oils, especially in boundary lubrication regimes. Many studies have been conducted in this matter. However, these are mainly focused on automotive industry additives and oils with high viscosity. The main contribution of the present study is exactly on this point, since the hydrogenated DLC (a-C:H) in a typical hermetic compressors for refrigeration scenario was evaluated, with low viscosity oils (~4.2 mm²/s). The pair chosen was a cylinder vs plane, where the cylinder slides in a reciprocating movement without rolling on a plane surface during a constant time and normal load pre-determined. Dry and lubricated tests were conducted with the same configurations. Wear scars were analyzed using optical and electronic microscopy, white light interferometry, Raman spectroscopy and EDS. The results show that the tribological behavior of tested pairs under dry conditions are governed by tribolayers, generated by oxidized debris submitted to contact conditions. Furthermore, graphitic carbon was found in these tribolayers. Under lubricated conditions, the coefficient of friction (COF) is reduced and the BTP additive reacts with metallic surfaces in order to form antiwear tribolayers. Ductile mechanisms act in wear of cast iron while DLC wear occurs due fragile mechanisms. The synergy between tribolayers originated from reactions of the additive and metallic surfaces and DLC graphitization during friction determine the tribological behavior of pairs involving DLC and gray cast iron.
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Aitamer, Marine. "Etude de la production de petites vésicules extracellulaires (dont les exosomes) dans les Lymphomes Diffus à Grandes Cellules B (DLBCL), influence de la voie BDNF/TrkB et impact sur la sensibilité des cellules tumorales aux anti-CD20." Thesis, Limoges, 2020. http://aurore.unilim.fr/theses/nxfile/default/d85d9c4c-cc57-4ab9-85be-dc07f311fd84/blobholder:0/2020LIMO0044.pdf.
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Le lymphome diffus à grandes cellules B (DLBCL) est un des lymphomes B non-Hodgkiniens le plus agressif et le plus fréquent chez l’adulte avec deux sous-groupes principaux (GCB et ABC) sur le plan biologique et clinique.Malgré les avancées thérapeutiques apportées par l’immunochimiothérapie R-CHOP (anti-CD20, rituximab, associé à la chimiothérapie CHOP), 30 à 40 % des patients échappent ou sont réfractaires au traitement. Des données récentes montrent que des petites vésicules extracellulaires, « small EVs » libérées par les cellules de DLBCL portent l'antigène CD20 jouant le rôle de « récepteur leurre » vis-à-vis de l'immunothérapie. L’objectif de cette thèse était d’étudier la production de ces « small EVs », dont font parti les exosomes, de façon comparative par les cellules de type GCB et ABC, ainsi que leur rôle dans l’échappement des cellules tumorales à la cytotoxicité du rituximab dépendante de l’activation du complément (CDC). Nous avons de plus poursuivi les travaux précédents de l’équipe sur le rôle de la voie de signalisation BDNF/TrkB dans ce processus. Dans ce contexte, nous avons analysé la production des « small EVs », et leur niveau d’expression du CD20, par les cellules traitées avec un agoniste de TrkB, le 7,8-DHF. Aucune différence significative de taille et de concentration de ces vésicules des lignées de type GCB et ABC n'a été observée. Le niveau de CD20 dans les « small EVs » était corrélé à l'expression du CD20 membranaire des cellules parentales, indépendamment du sous-type de DLBCL. De manière intéressante, une expression plus élevée du CD20 au sein de ces vésicules et de la concentration en « small EVs » ont été observées dans les cultures traitées au 7,8-DHF comparativement aux cultures contrôles. Nous avons montré in vitro et in vivo (xénogreffe de SUDHL4 chez des souris SCID) que l'association de « small EVs » autologues ou hétérologues au rituximab protégeait les cellules tumorales et les tumeurs de la cytotoxicité du rituximab. De plus, la protection était significativement améliorée lorsque les exosomes étaient produits par des cellules traitées au 7,8-DHF. Enfin, une étude préliminaire a été initiée sur la signification clinique des « smallEVs », dont les exosomes plasmatiques et leur niveau d’expression du CD20 chez des patients atteints de DLBCL comparativement à des volontaires sains (VS). Nous montrons pour la première fois dans le DLBCL une augmentation de leur concentration périphérique par rapport aux VS. L’ensemble des travaux confirment in vivo le rôle des « small EVs » dans l'échappement à l’immunothérapie des tumeurs de DLBCL, et mettent en évidence à travers la voie BDNF/TrkB l’influence de circuits de régulations sur ce processus. Finalement ils apportent des arguments sur l’utilisation potentielle des « small EVs », dont les exosomes, comme biomarqueurs non-invasifs de la charge tumorale et de l’expression de cibles thérapeutiques comme le CD20, dans le suivi de la maladie et l’orientation thérapeutiqueDiffuse large B-cell lymphoma (DLBCL) is one of the most aggressive and common non-Hodgkin B lymphomasin adults with two major biologically and clinically subgroups (GCB and ABC). Despite the therapeutic advances provided by R-CHOP immunochemotherapy (combination of an anti-CD20, rituximab, with CHOP chemotherapy), 30 to 40% of patients escape or are refractory to treatment. Recent data show that small extracellular vesicles, “small Evs”, released by DLBCL cells carry the CD20 antigen playing as a "decoy receptor" for immunotherapy. The objective of this thesis was to study comparatively the production of these “small EVs” including exosomes, by GCB and ABC cell lines, as well as their role in the escape of tumor cells from complement dependent cytotoxicity (CDC) of rituximab. We have further extended the team's previous work in analyzing the role of the BDNF/TrkB pathway in this process. In this context, production of “small Evs” and their CD20 level were studied in cells treated or not with a TrkB agonist, 7,8-DHF. No significant difference in size and concentration of these vesicles of GCB and ABC type lines was observed. The level of CD20 in “small Evs” was correlated with CD20 surface expression in parental cells, independently of the DLBCL subtype. Interestingly, higher expression of CD20 within these vesicles and the concentration of "small Evs” were found in cultures treated with 7,8-DHF compared to control cultures. We demonstrated in vitro and in vivo (SUDHL4 xenograft in SCID mice) that combination of autologous or heterologous “small Evs” with rituximab protects tumor cells and tumors from the rituximab cytotoxicity. In addition, protection was significantly improved when ”small Evs” were produced by cells treated with 7,8-DHF. Finally, a preliminary study was initiated on the clinical significance of plasma “small Evs” including exosomes, and their CD20 level in patients with DLBCL compared to healthy volunteers (VS). We show for the first time in DLBCL an increase in their peripheral concentration compared to VS. Altogether, our results confirm in vivo the role of “small Evs” in DLBCL cell evasion from immunotherapy that could be modulated by environmental factors as shown in the present study for BDNF/TrkB pathway. Finally, they argue that “small Evs” incliding exosomes could be used as non-invasive biomarkers of tumor burden and expression of therapeutic targets such as CD20, for disease monitoring and therapeutic orientation
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De, Feo Modestino. "Impact du vieillissement de l'additif MoDTC sur ses propriétés tribologiques pour les contacts acier-acier et DLC-acier." Thesis, Ecully, Ecole centrale de Lyon, 2015. http://www.theses.fr/2015ECDL0054/document.
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La législation européenne sur les émissions des véhicules devient de plus en plus sévère et ceci afin de minimiser l'impact sur l'environnement de la pollution occasionnée par les moteurs à combustion interne. La réduction des pertes par frottement et une plus faible consommation du carburant représentent différents aspects sur lesquels il est possible d’intervenir dans ce sens. Pour diminuer les pertes par frottement, plusieurs approches ont été utilisées, soit au niveau du design des pièces mécaniques, soit au niveau de l’optimisation du lubrifiant pour un contact considéré. Le dithiocarbamate de molybdène (MoDTC) est l’un des additifs modificateur de frottement permettant d’atteindre les plus faibles coefficients de frottement pour un contact acier/acier lubrifié en régime limite. La molécule se décompose dans le contact à des températures et des pressions élevées, en formant des feuillets lamellaires de MoS2 sur les surfaces frottantes. Cependant, il est nécessaire d'optimiser la durée de vie de ces additifs, en empêchant leurs appauvrissements ou dégradations prématurés dans le lubrifiant. Il a été montré, en effet, que les performances du MoDTC sont sensibles au temps de fonctionnement du moteur et sont donc liées à sa dégradation. L'objectif principal de cette thèse était donc de mieux comprendre le comportement tribologique (frottement et usure) d’une huile de base contenant du MoDTC en fonction de la dégradation du lubrifiant pour des contacts acier/acier et DLC/acier. L’approche utilisée pour mieux comprendre le comportement du MoDTC lorsqu'il est soumis à une dégradation thermo-oxydative consiste à combiner des expériences tribologiques, à des caractérisations de surface (XPS, FIB / TEM / EDX, Raman, SEM) et à des caractérisations chimiques des huiles (chromatographie en phase liquide, spectroscopie de masse, FT-IR). Un lien direct et cohérent entre la composition du tribofilm et la voie de décomposition chimique de l'additif MoDTC proposée a été mise en évidence. Les additifs modernes sont conçus pour être utilisés sur des surfaces à base de fer. Il est donc essentiel d'optimiser simultanément les lubrifiants et les revêtements pour améliorer leurs performances. Dans cette thèse, un modèle d'usure du revêtement DLC hydrogéné lubrifié en présence de MoDTC a été proposé. Nous avons établi à l’aide de plusieurs techniques, que l’usure est due principalement à la formation de carbure de molybdène présent dans le tribofilm formé à la surface de l’acierEuropean legislation on vehicle emissions continues to become more severe to minimize the impact of Internal Combustion Engines (ICE) on the environment. One area of significant concern in this respect is the reduction of friction losses resulting in reduced emissions and as well as higher fuel efficiency and lower fuel consumption. To decrease these losses, several approaches have been made particularly at design of mechanical parts stage and at experimental level to optimize lubricant components. A great contribution to solve the problem can be given by the optimization of the additives package blended into the engine lubricants. The molybdenum dithiocarbamate (MoDTC) is the additive showing the best tribological performance by acting as friction modifier. It decomposes under high temperatures and pressure, forming layered structures on the engine surfaces. However, the use of effective friction reducing additives to achieve low boundary friction coefficient is not enough to have great engine fuel efficiency. In addition, in fact, it is needed also to maximize their durability, preventing premature consumption or depletion of these additives. It has been shown, in fact, that the friction reduction performance of MoDTC is sensitive to engine operating time and that is related to the degradation of MoDTC itself. In the first part of my thesis we tried to get a good comprehension of the chemical mechanisms of MoDTC ageing and to study the impact on the tribological properties. The chemical bulk oil characterization of MoDTC blended into the base oil when subjected to thermo-oxidative degradation allowed to propose a new hypothetical chemical pathway followed by the friction modifier molecules during the ageing process. At the same time, these findings were linked to the impact of the MoDTC degradation on its tribological properties. As reported in literature, another MoDTC drawback is its strong antagonism with DLC coating. In fact, when DLC-involving contacts are lubricated by MoDTC-containing base oil, a catastrophic DLC wear is produced. For this reason, in the second part of the project a multi-techniques approach has been adopted to get a better understanding of this wear mechanism. The combination of all the findings allowed to propose for the first time a new wear mechanism based on the formation of molybdenum carbide species inside the contact. A strong chemical interaction between the molybdenum-based species formed on the steel counter-body and the carbon of the DLC material has been supposed, leading to the formation of MoC species. All the results found are discussed to clarify the correlation between degradation time, tribological performance and tribofilm characterizations in both steel/steel and DLC/steel contact
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Antunes, Renato Altobelli. ""Caracterização do comportamento frente à corrosão de um aço inoxidável austenítico para aplicações biomédicas com revestimentos PVD de TiN, TiCN e DLC"." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-30052007-161859/.
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Biomateriais metálicos devem apresentar uma combinação de propriedades como resistência à corrosão, biocompatibilidade e resistência mecânica. Os aços inoxidáveis austeníticos, especialmente do tipo AISI 316L, aliam estas propriedades com a possibilidade de fabricação a um baixo custo. No entanto, são susceptíveis à corrosão nos fluidos fisiológicos e seus produtos de corrosão podem causar reações alérgicas ou infecciosas nos tecidos vizinhos ao implante. No presente trabalho, a aplicação de revestimentos obtidos por processos de deposição física de vapor (PVD) sobre um aço inoxidável austenítico do tipo AISI 316L foi realizada a fim de aumentar sua resistência à corrosão e biocompatibilidade. Os filmes depositados foram de nitreto de titânio (TiN), carbonitreto de titânio (TiCN) e de carbono tipo diamante (DLC). Estes materiais têm alta dureza e resistência ao desgaste, além de biocompatibilidade intrínseca, características altamente desejáveis para aplicações biomédicas. A caracterização do comportamento eletroquímico do aço com os três tipos de revestimentos mostrou que a presença de defeitos na superfície das camadas depositadas exerce uma influência negativa sobre a resistência à corrosão do substrato. A presença dos defeitos foi evidenciada por microscopia eletrônica de varredura. Foi proposto um mecanismo, com base nos dados obtidos por espectroscopia de impedância eletroquímica, para explicar a evolução do comportamento eletroquímico do aço com os diferentes revestimentos ao longo do tempo de imersão. Foram também empregados dois tratamentos de passivação da superfície do aço em soluções de ácido sulfúrico e ácido nítrico, a fim de aumentar a resistência à corrosão do substrato. Os resultados indicaram que os tratamentos utilizados não foram eficientes para melhorar esta característica, mas podem ser modificados visando um desempenho superior. As propriedades eletrônicas dos filmes passivos formados, tanto sobre o aço sem tratamento de passivação como sobre o aço passivado, foram estudadas utilizando a abordagem de Mott-Schottky. Os filmes apresentaram um caráter duplex, mostrando comportamento de um semicondutor altamente dopado acima e abaixo do potencial de banda plana. A concentração de dopantes no filme passivo foi associada à resistência à corrosão do material. Os três revestimentos PVD investigados apresentaram comportamento não citotóxico. Considerando a diminuição do coeficiente de atrito do aço 316L, os revestimentos de TiCN e o DLC foram os mais eficientes. Estas características, aliadas ao fator custo, sugerem que a aplicação comercial destes materiais sobre implantes ortopédicos pode ser viável. No entanto, a resistência à corrosão, conforme a avaliação realizada no presente estudo, não foi adequada quando comparada ao desempenho do aço sem nenhum tipo de revestimento. Ao final do texto, são apresentadas algumas sugestões a fim de conseguir um desempenho superior para a capacidade protetora dos revestimentos PVD.Metallic biomaterials must present a combination of properties such as corrosion resistance, biocompatibility and mechanical resistance. Austenitic stainless steels, especially AISI 316L combine these properties with the easy of fabrication at low cost. However, they are prone to corrosion in physiological solutions. Furthermore, their corrosion products may lead to infectious ou allergenic reactions in the tissues around the implant device. In the present work, coatings produced by physical vapour deposition (PVD) methods have been applied on the surface of a 316L stainless steel to increase its corrosion resistance and biocompatibility. Three thin films were tested: titanium nitride (TiN), titanium carbonitride (TiCN) and diamond-like carbon (DLC). These materials present high hardness, wear resistance and intrinsic biocompatibility that are key features when considering biomedical applications. The characterization of the electrochemical behavior of the stainless steel coated with the three different films showed that the presence of surface defects are deleterious to the corrosion resistance of the substrate. These defects were observed using scanning electron microscopy. The evolution of the electrochemical behavior of the coated steel was explained through a mechanism based on the experimental results obtained using electrochemical impedance spectroscopy. Two different passivation treatments were carried out on the stainless steel surface, either in sulfuric or nitric acid solutions, to increase its corrosion resistance. The results suggested que these treatments were not efficient, but may be modified to improve its performance. The electronic properties of the passive films of the non-passivated and passivated stainless steel were studied using the Mott-Schottky approach. The films presented a duplex character. Below the flatband potential the behavior is typical of a highly doped type-p semiconductor. Above the flatband potential is typical of a highly doped type-n semiconductor. The doping concentration in the passive film was determined and associated with the corrosion resistance of the substrate. All PVD coatings investigated showed non-cytotoxic behavior. DLC and TiCN coatings decreased the friction coefficient of the stainless steel substrate. These properties allied with the stainless steel low cost recommend their commercial use for implants materials purposes. Nevertheless the corrosion resistance presented by the coated-steel was inferior to that of the bare steel and should be improved. At the end of the present text, some suggestions are proposed in order to improve the corrosion protection performance of the PVD coatings.
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Arnaud, Nicolas. "Les lymphomes B diffus à grandes cellules de type activé : rôle de NF-κB et c-Myc." Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0105/document.
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A l’instar du lymphome de Burkitt (LB) avec la translocation de MYC, les lymphomes diffus à grandes cellules B (DLBCL) par d'autres mécanismes (mutation, amplification, dérégulation du promoteur) sont associés à une dérégulation de c-Myc, facteur de transcription maitre de la prolifération. Les DLBCL sont classés en deux sous-groupes: « centre germinatif » (GCB) et « cellule B activée » (ABC) avec activation constitutive de NF-κB. Cette activation constitutive de NF-κB peut être le résultat d'altérations génétiques (MYD88, A20, TRAF2 et TRAF5) ou de l'activation du BCR ou CD40. Ces caractéristiques soulèvent la question de la synergie d’action entre NF-κB et c-Myc dans les ABC-DLBCL. Nous avons analysé l’effet d'une activation continue de c-Myc dans un contexte de sur-activation de NF-κB par plusieurs inducteurs. Nos résultats montrent que la surexpression de c-Myc dans un contexte d'induction de NF-κB, i) par le programme EBV latence III, apporte un avantage sélectif à ces cellules (expression génique en faveur d'un métabolisme élevé, prolifération intense et protection contre apoptose), ii) par le TLR9 (modèle in vivo et in vitro), augmente la survie et la prolifération des lymphocytes B des souris λc-Myc (augmentation des cellules B activées, splénomégalie, augmentation de la prolifération des lymphocytes B, modification du microenvironnement tumoral), et iii) par CD40, induit une lymphomagenèse B très agressive dans les souris doubles transgéniques CD40/Myc, les tumeurs ont un phénotype proche des ABC-DLBCL. Ces résultats suggèrent que c-Myc est un événement co-transformant dans les lymphomes agressifs avec un phénotype activé par NF-κB, tel que les ABC-DLBCLNot only Burkitt lymphoma (BL) with the translocation of MYC, but also diffuse large B-cell lymphoma (DLBCL) by other mechanisms (mutation, amplification, promoter dysregulation…) are associated with dysregulation of c-Myc, the master transcription factor for proliferation. DLBCL’s are classified in two subgroups: “Germinal center B-cell” (GCB) without and “activated B-cell” (ABC) with constitutive NF-κB activation. This constitutive activation of NF-κB can be the result of genetic alterations (MYD88, A20, TRAF2, and TRAF5) or the activation of B-cell receptor or CD40. These features raise the question of the synergy of action between NF-κB and c-Myc in ABC-DLBCL. We analyzed the effect of a continuous activation of c-Myc in a context of over-activation of NF-κB by several inductors. Our results show that overexpression of c-Myc in the context of induction of NF-κB, i) by EBV latency III program, provides a selective advantage to those cells (gene expression in favor of a high metabolism, intense proliferation and protection against apoptosis), ii) by TLR9 (in vivo and in vitro model) increases the survival and proliferation of B lymphocytes of λc-Myc mice (increase of activated B cells, splenomegaly, increased B cells proliferation, modification of tumor microenvironment), and iii) by CD40, induces a very aggressive B lymphomagenesis in CD40/Myc double transgenic mice, the tumors have a phenotype close to ABC-DLBCL. These results suggest that c-Myc is an NF-κB co-transforming event in aggressive lymphomas with an activated phenotype by NF-κB, such as ABC-DLBCL
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Berehab, Mimoune. "Cell-killing profile of thymoquinone toward malignant B lymphocytes from diffuse large B cell lymphoma and underpinning mechanisms." Doctoral thesis, Universite Libre de Bruxelles, 2017. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/258433.
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Une meilleure compréhension des mécanismes moléculaires impliqués dans la malignité des lymphome B diffus à grande cellules (LBDGC) et dans leur résistance aux traitements devraient permettre de développer de nouvelles opportunités thérapeutiques innovantes et d’envisager dans un futur proche de nouveaux agents de thérapie ciblée. Jusqu’à ce jour, le traitement standard se solde encore par un échec chez un nombre significatif de patients. Les rechutes post traitement et les cas réfractaires restent le défi majeur pour améliorer le taux de survie global. Plusieurs méchanismes ont été décrits comme responsables de ces échecs, dont, pour une grande part, le dysfonctionnement de la machinerie apoptotique. Dès lors, des stratégies thérapeutiques activant des voies non-apoptotiques plus sélectivement dans les cellules malignes sont absolument nécessaires. La Thymoquinone (TQ), un principe actif isolé de la plante médicinale Nigell a Sativa, a démontré des propiétés anticancéreuses in vitro ainsi que dans des modèles animaux, en agissant via plusieurs mécanismes incluant principalement des effets antiprolifératifs et pro-apoptotiques. Malgré les nombreuses investigations, les mécanismes de destruction cellulaire sous-jacents à l’effet anti-cancéreux de la TQ restent ambigus et peu élucidés, notament sur les voies de mort cellulaire non-apoptotiques. L’objectif de notre travail vise l’évaluation de la sélectivité de la TQ vis-à-vis des lignées cellulaires de lymphomes B diffus à grandes cellules (LBDGC), et l’élucidation des méchanismes critiques responsables de la destruction cellulaire. Dans une première partie, nous avons démontré la capacité de la TQ à produire un effet cytotoxique plus prononcé dans des lignées cellulaires lymphomateuses (LBDGC) par rapport aux cellules normales provenant de donneurs sains. Le profil de sélectivité de la TQ s’est avéré intéressant par rapport aux agents de chimiothérapie conventionnelle dans le LBDGC. A l’échelle moléculaire, on a mis en évidence l’implication de voies de mort cellulaire non-apoptotiques, en supplément des voies apoptotiques, dans l’effet cytotoxique de la TQ dans la plupart des lignées étudiées. Nos investigations ont d’abord révélé un effet pro-apoptotique vraisemblablement sous-jacent à l’effet génotoxique de la TQ. L’importance de cette modalité de mort cellulaire dans l’effet cytotoxique de la TQ est toutefois limitée aux lignées les moins sensibles. Nos observations ont révélé la capacité de la TQ à activer la voix mitochondriale des caspases suite à la libération du cytochrome c. La mort cellulaire produite par la TQ n’est toutefois pas freinée par l’inhibition des caspases, et nos investigations ont également exclu l’implication des voies apoptotiques caspases-indépendantes. Paradoxalement, ces investigations ont montré le rôle critique des voies de mort cellulaire non-apoptotiques, en particulier dans les lignées sensibles à l’effet de la TQ. En étudiant l'origine de cette voie alternative de mort cellulaire, on a constaté que la TQ provoque le dysfonctionnement réticulaire qui se manifeste par l’activation des voies de transduction UPR et se produit de façon plus significative dans les lignées sensibles. En effet, dans cette dernière catégorie nos investigations ont démontré que la TQ produit un effet important par l’augmentation du calcium cytosolique principalement via la dépletion de celui-ci à partir des compartiments réticulaires. En accord avec ces observations, nous avons demontré que l’augmentation du calcium cytosolique joue un rôle critique, plus particulièrement dans l’effet non-apoptotique de la TQ opérant principalement dans les lignées fort sensibles aux effets de la TQ. Afin de mieux caractériser les mécanismes de susceptibilité et de résistance des lignées LBDGC, la deuxième partie de ce travail a été consacrée à l’évaluation de l'implication de l’histone déacétylase SIRT1 ( silent information regulator 1) dans la sensibilité des lignées aux effets de la TQ. SIRT1 intervient notament dans la résistance au stress oxydatif et à l’apoptose. SIRT1 serait également protectrice contre les dommages à l'ADN. Rappelons que l’expression de SIRT1 est considérée comme un facteur de mauvais pronostic pour les patients atteints de LBDGC. En focalisant nos investigations sur les lignées résistantes aux traitementx standard et moins sensibles à la TQ, nous avons démontré l'effet protecteur de SIRT1 vis-à-vis de l'effet pro-apoptotique et génotoxique de la TQ. En résumé, la capacité de la TQ à déclencher des modalités de mort cellulaire non apoptotiques pourrait constituer une stratégie prometteuse pour surmonter les mécanismes anti-apoptotiques responsables en partie de l’échec du traitement standard. Tenant compte du rôle critique de l’effet génotoxique dans le traitement des LBDGC, notre travail suggère que l'inhibition de SIRT1 pourrait être une stratégie préventive pour surmonter la résistance native ou acquise. D’autre part, nos résultats contribuent à une compréhension plus précise des mécanismes critiques responsables de l’effet cytotoxique de la TQ. Nos travaux pourraient d’autre part permettre l’étude de combinaisons innovantes de médicaments incluant la TQ in vivo.Doctorat en Sciences biomédicales et pharmaceutiques (Médecine)
info:eu-repo/semantics/nonPublished
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Ko, Chi-fat, and 高自發. "Molecular regulations of deleted in liver cancer (DLC) protein family." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B41896889.
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Ko, Chi-fat. "Molecular regulations of deleted in liver cancer (DLC) protein family." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B41896889.
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Corcuera, Valerie Cecile. "Filmes de DLC com nanocristais de diamante para aplicações espaciais." Instituto Nacional de Pesquisas Espaciais (INPE), 2016. http://urlib.net/sid.inpe.br/mtc-m21b/2016/06.23.18.37.
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Devido à tendência de aglomeração o desenvolvimento na funcionalização e posterior dispersão do pó de nanodiamante (ND) produzido por detonação pode se tornar um desafio. O pó do ND foi purificado por meio de tratamento térmico e dois tipos de funcionalizações foram alcançadas ND-COOH e ND-H. A purificação e as funcionalizações foram alcançadas com sucesso e foram verificadas por TGA e FT-IR. A análise de AFM mostrou que o tratamento térmico de oxidação que fornece a funcionalização do ND-COOH reduz os aglomerados em cerca de 74\% do tamanho original. O tamanho médio dos aglomerados do ND-COOH conforme medido por dispersão dinâmica de luz foi substancialmente reduzido em 95\% do tamanho original após a funcionalização e desagregação mecânica do pó em meio líquido. A estabilidade da dispersão do ND em solvente polar tetrahidrofurano aumentou consideravelmente apresentando um potencial zeta de -31 mV. Esta tese contemplou o desenvolvimento de uma nova metodologia para a dispersão dos aglomerados de nanodiamante (ND) em meio líquido. Filmes de carbono tipo diamante (DLC - Diamond-Like Carbon) contendo nano partículas de diamante foram depositados sobre amostras planas de liga de titânio Ti6Al4V pela técnica de DC pulsada PECVD (Plasma Enhanced Chemical Vapor Deposition). Soluções precursoras para deposição de filme de DLC foram preparadas. Filmes de DLC e DLC-ND foram produzidos a partir de diferentes solventes de natureza polar e apolar e as suas propriedades foram avaliadas. Análises comparativas de perfilometria, coeficiente de atrito, espectroscopia de espalhamento Raman foram abordadas. As análises de MEV e AFM revelaram a presença do ND no filme.Due to agglomeration tendency the development of functionalization and subsequent dispersion of detonation nanodiamond (ND) powder can become a challenge. ND powder was purified by heat treatment and two types of functionalizations were achieved ND-H and ND-COOH. Purification and functionalizations were successfully achieved and were verified by TGA and FT-IR. AFM analysis showed that the thermal oxidation treatment which provides ND-COOH functionalization reduces the agglomerates in about 74\% of the original size. The average size of ND-COOH agglomerates as measured by dynamic light scattering has been significantly reduced by 95\% of its original size after functionalization and mechanical shearing of the powder in a liquid medium. The stability of ND dispersion in polar solvent tetrahydrofuran increased considerably having a zeta potential of -31 mV. Development of a new method for the dispersion of agglomerated nano diamond (ND) in a liquid medium was included in this thesis. Diamond-Like Carbon (DLC) films with nano diamand particles were deposited on flat samples of titanium alloy Ti6Al4V by pulsed DC Plasma Enhanced Chemical Vapor Deposition (PECVD). Precursor solutions for DLC films deposition were presented. DLC and DLC-ND films were produced from different polar and nonpolar solvents and their properties were evaluated. Comparative analyzes profilometry, friction coefficient, Raman spectroscopy have been addressed. SEM and AFM analysis revealed the presence of ND in the film.
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Lehmkühl, Niklas, and Raoul Man. "How Do Different DLC Delivery Methods Impact Appeal and Effectiveness." Thesis, Uppsala universitet, Institutionen för speldesign, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-388641.
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Downloadable content (DLC) distribution models employ various methods to keep consumers interested. Some methods encourage consumers to purchase and engage with a DLC model and some methods discourage consumers from engaging with the model. This study seeks to determine which models keep consumers interested and which discourage consumers from purchasing DLC. We do this by reaching out to multiplayer communities of four different games that are affected by different models and have them fill out a survey regarding their purchasing behaviour. After analysing the results, we concluded that models that require players to own the same DLC in order to play together or that utilize watermarks for DLC that are not owned, are less effective at incentivizing players to purchase when compared to models that either allow players to share DLC, or acquire it through in-game means.Distributionsmodeller för nedladdningsbart innehåll använder olika metoder för att hålla konsumenterna intresserade. Vissa metoder uppmuntrar konsumenter att köpa och engagera sig i en DLC-modell och vissa metoder avskräcker konsumenterna från att engagera sig med modellen. Denna studie syftar till att bestämma vilka modeller som håller konsumenterna intresserade och som avskräcker konsumenterna från att köpa DLC. Vi gör det genom att nå ut till multiplayer-grupper i fyra olika spel som påverkas av olika modeller och få dem att fylla i en undersökning om deras inköpssätt. Efter att ha analyserat resultaten drog vi slutsatsen att modeller som kräver att spelare äger samma DLC för att kunna spela tillsammans eller använda vattenstämplar för DLC som inte ägs, är mindre effektiva för att stimulera spelare att köpa jämfört med modeller som antingen tillåter spelare att dela DLC, eller skaffa det via in-game-medel.
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Yang, Liuquan. "DLC/friction reduction additives interactions in the boundary lubrication regime." Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/10121/.
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Friction has enormous effect on energy consumption and wear limits the life time of many mechanical devices with relative motion components. The challenges in the automotive industry have been driven by fuel economy as well as stringent emission legislation for environmental sustainability. Improvements of coating deposition technology enable the mass production of high quality Diamond-Like Carbon (DLC) coatings at an industrial scale and also increase their use in lubricated contacts. However, the understanding of the interactions of different lubricant additives with this material is not yet fully developed. This study focused on several fundamental aspects of the tungsten-doped DLC coating (denoted as WDLC) behaviour under boundary lubrication conditions with model lubricants. Zinc dialkyldithiophosphate (ZDDP), glycerol monooleate (GMO) and molybdenum diakyldithiocarbamate (MoDTC) were used in these model lubricants. The primary test contact was semi-coated, i.e., WDLC vs. cast iron (CI). As references, steel/CI, non-doped DLC coating (NDLC)/CI and fully coated WDLC/WDLC interfaces were also studied. As the primary focus, WDLC/CI interface was tested not only at 100 °C, but also a wider service temperature from 30 °C to 150 °C. For the other references, tests were only carried out at 100 °C. The tribological tests were carried out by Cameron Plint TE77 reciprocating tribometer. Test simulation was based on the liner motion part of the camshaft/follower system in an internal combustion engine (ICE). This study demonstrated the characterization of WDLC coating lubrication by Raman spectroscopy. The effect of lubricant additives on the coating structure change was discussed in terms of carbon structure and the tungsten dopant. Electron Energy Loss Spectroscopy (EELS) and Raman spectroscopy characterization for the upper carbon layers indicated that the WDLC coating interacted chemically with selected lubricant additives. The testing temperature was proved to be critical in WDLC lubrication. The study also clarified the role of doping tungsten and its unique role in changing the tribological behaviours of DLC lubrication with references to NDLC coating tests. The fully coated WDLC/WDLC tests clarified further the tribofilm formation dependence of ferrous surface for ZDDP and MoDTC additives. The formation of tribofilm of GMO on WDLC coated surface had less dependence than on ferrous materials. Different models of lubrication in semi-coated WDLC/CI interface were proposed individually in the concluding chapters and the role of tungsten carbide in changing the tribochemical interaction of GMO+ZDDP lubricant compared with NDLC/CI interface was further discussed. Overall, this study provided fundamental aspects for better understanding of interactions between current ferrous based additives (with a further reduced treat rate) and WDLC coating in a semi-coated tribological system. The methodology and results should contribute both the fundamental science and engineering practices which the engineering science community should be benefited from.
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Ernesto, André. "Lubrification colloïdale de contacts DLC : du régime stationnaire au régime transitoire : application à la zone segments - piston - chemise." Thesis, Ecully, Ecole centrale de Lyon, 2014. http://www.theses.fr/2014ECDL0035/document.
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Les enjeux écologiques liés au réchauffement climatique, et plus généralement la lutte contre la pollution, ont occasionné une révolution sans précédent dans le domaine des transports. De nombreuses recherches portant sur l’identification de voies d’amélioration du rendement mécanique des moteurs à combustion interne ont été menées au cours de ces dernières décennies. Dans les moteurs Diesel, le contact Segments-Piston-Chemise (SPC) représente à lui seul près de 40 % des pertes d’énergie par frottement mécanique totales du moteur. Ce travail de thèse s’inscrit dans le cadre général de la lubrification des moteurs Diesel en présence de suies et s’intéresse plus particulièrement au poste SPC pour des contacts Diamond-Like Carbon (DLC) lubrifiés. Ce travail de thèse s’appuie sur des outils de tribométrie originaux pour reproduire les cinématiques particulières des contacts impliqués au niveau de la segmentation. Cette thèse s’attache à identifier l’influence d’un lubrifiant vieilli en fonctionnement sur les mécanismes de lubrification et les mécanismes de frottement associés de couches minces dures de type DLC, en balayant l’ensemble des régimes de lubrification pour des conditions stationnaires et transitoires. Les revêtements DLC développés dans le cadre de ce travail de thèse ont permis de diminuer significativement le frottement limite en conditions stationnaires et transitoires. La déstructuration du lubrifiant via la formation d’agrégats, générés par le passage des suies, ou par une annulation temporaire de la vitesse d’entraînement représentative des cinématiques de contact observées en zone SPC, sont gouvernés par le triptyque, lubrifiant, surface et cinématique de contact. Enfin, l’analyse de la réponse tribologique de l’interface lubrifiée en conditions stationnaires et transitoires permet à la modélisation théorique du frottement lors d’un cycle complet de glissement à vitesses variablesEcological issues related to global warming, and more generally the reduction of pollution, have lead to a major revolution in the field of transport. Considerable research work has been carried out during the past decades in order to improve the mechanical efficiency of internal combustion engines. In Diesel engines, almost 40 % of total engine energy losses due to mechanical friction occur in the Piston rings-Piston-Cylinder contact (PPC). The overall framework of this PhD thesis is Diesel engine lubrication in presence of soot and this work focuses more particularly on Diamond-Like Carbon (DLC) lubricated contacts for PPC region. Unique tribometry tools are used to reproduce the particular contact kinematics involved in the piston assembly. This thesis aims to identify the influence of an aged lubricant on the lubrication and friction mechanisms of DLC hard coatings for all lubrication regimes in steady-state and transient conditions. DLC coatings developed during this thesis significantly reduce the boundary friction in steady-state and transient conditions. The lubricant destructuring due to aggregate formation, generated by the passage of soot, or by a temporary vanishing of the entrainment speed, are governed by the triplet, lubricant, surface and contact kinematics. Finally, the analysis of the tribological response of the lubricated interface in steady-state and transient conditions leads to the theoretical modeling of the friction during a complete cycle of sliding at variable velocities
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Sarosiek, Kristopher A. "Interleukin-21 Induces Apoptosis of Diffuse Large B Cell Lymphomas via Activation of the STAT3 - c-Myc Intracellular Signaling Pathway." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_dissertations/473.
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Interleukin-21 (IL-21), a recently discovered member of the IL-2 cytokine family, has been shown to have diverse regulatory effects on B cells including the induction of antibody secretion, differentiation, or apoptosis depending on the cell milieu and activation status. However, the effects of IL-21 on B cell neoplasms such as diffuse large B cell lymphoma (DLBCL) are largely unknown. Our research uncovered the widespread expression of the IL-21 receptor (IL-21R) in B cell lymphomas including DLBCL and that IL-21 stimulation resulted in potent phosphorylation of STAT1 and 3 and weak activation of STAT5. However, our findings also showed that treatment of DLBCL cell lines with IL-21 induced cell cycle arrest and apoptosis. The cell death was caspase-dependent and evident in a majority of DLBCL cell lines. To further examine the potential therapeutic applicability of IL-21, we assessed the effects of IL-21 on primary DLBCL tumors and in vivo DLBCL xenografts in mice. In primary tumors, IL-21 induced apoptosis in five of five DLBCLs compared to two of three follicular lymphomas and two of seven chronic lymphocytic leukemias. No apoptosis or cell death was induced in normal peripheral B lymphocytes. In mice bearing DLBCL xenograft tumors, in situ IL-21 injections induced tumor regression and dramatically extended the overall survival of mice (P<0.001). To elucidate the mechanism of IL-21-induced cell death we analyzed the expression of apoptosis-regulating proteins and observed a strong downregulation of anti-apoptotic Bcl-2 and Bcl-XL and an upregulation of pro-apoptotic Bax post IL-21 stimulation. Subsequent experiments showed that ectopic expression of Bcl-2 or Bcl-XL was able to partially reduce cell death induced by IL-21 while Bax knockdown with siRNA blocked apoptosis completely. To gain insight into the signaling pathways shifting the expression of these proteins toward cell death we performed microarray analysis on sensitive and resistant DLBCL cell lines. The most striking difference in gene expression was observed in C-MYC which was only induced in cell lines exhibiting apoptosis upon IL-21 treatment. Previous reports have shown that c-Myc, which has been studied extensively for its oncogenic properties, can induce apoptosis via downregulation of its transcriptional targets Bcl-2 and Bcl-XL. We then showed that IL-21-induced cell death is dependent on c-Myc by utilizing specific siRNA and shRNA to block the upregulation of this transcription factor and prevent apoptosis. Since c-Myc is a bona-fide target of STAT3 we also showed that siRNA-mediated knockdown of STAT3 abrogated apoptosis by preventing c-Myc upregulation and its subsequent effects on apoptosis-regulating proteins. Our results delineate a novel IL-21 pro-apoptotic signaling pathway and one of the first examples in which the STAT3 - c-Myc pathway, which usually promotes B cell survival and oncogenesis, can be exploited for treatment of cancer. Furthermore, our findings demonstrate that IL-21 is a highly potent anti-DLBCL agent in vitro and in animal models and should be examined in clinical studies of DLBCL.
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Li, Jingyun. "Lapped transforms based on DLS and DLC basis functions and applications." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30101.pdf.
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binti, Nik Roseley Nik Roselina. "Fabrication and characterisation of DLC-graphene nanocomposite coatings for tribological application." Thesis, University of Leeds, 2019. http://etheses.whiterose.ac.uk/22712/.
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This work presents the development and characterisation of single and multilayer Diamond-Like Carbon (DLC)-graphene nanoplatelet (GNP) nanocomposite coatings. This study opens up a new challenge in the fabrication of carbon composites using DLC and GNP with enhanced mechanical and tribological properties. The purpose of the composite is to exploit the advantages of the excellent mechanical and tribological properties of graphene that have been reported by many works. The objectives of this thesis are to develop a method to fabricate DLC and GNP nanocomposite coatings, to prepare the nanocomposite coatings and to investigate their physical, mechanical and tribological properties. The fabrication of DLC-GNP nanocomposite coatings was carried out using the combination of spin coating of GNP and DLC deposition using PECVD. The two types of DLC-GNP that have been prepared are single-layer and multilayer. The surface morphology and microstructure of DLC-GNP was characterised using optical microscopy and Scanning Electron Microscopy (SEM). Focused Ion Beam (FIB) SEM was used to observe the layers in the composite and measure the thickness of the multilayer DLC-GNP nanocomposite coating. The coating comprises the interlayer, spin-coated GNP and DLC film. This study shows that an optimised post-treatment is required to substantially improve the adhesion strength of spin-coated GNP and thus that of the whole nanocomposite coating. It was observed that columnar structure was generated in-situ during a wear tests on coatings post-treated for more than 180 minutes. The results were unintentionally found after three hours of sliding test. The columnar structure contributed to the significant reduction of the coefficient of friction (CoF) to 0.06, and the wear rate compared to other samples. According to Raman spectroscopy analysis, both single and multilayer DLC- GNP nanocomposite coatings have typical spectra similar to that of pure DLC. However, DLC-GNP has a broad range of ID/IG ratio values compared to pure DLC due to the dispersion of spin-coated GNP. The observation though cross-section FIB also proved that DLC film covered the spin-coated GNP by creating a bonding layer during DLC film deposition. The multilayer DLC-GNP demonstrated major improvements in adhesion strength of almost doubling the value obtained by single-layer DLC-GNP. The wear resistance also increased remarkably which can be related to the enhancement of adhesion strength. It is proposed that the GNP in the composite is released during the running-in period and acted as a slider between the counterpart and coating.
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Peng, Xilin. "Synthesis and adhesion of diamond and diamond-like carbon (DLC) films." Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624958.
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Hofmann, Dieter. "Si-DLC coatings optimized for low wear and low friction applications." Thesis, Sheffield Hallam University, 2014. http://shura.shu.ac.uk/19805/.
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Diamond-like carbon (DLC) has excellent properties for the use as tribological coating such as high hardness, high wear resistance and a low friction coefficient. Nanolayer systems of hydrogenated diamond-like carbon (a-C:H) and silicon doped hydrogenated diamond-like carbon (Si-DLC or a-C:H:Si) have been studied. The objectives of this work are to develop layer combinations which allow combining low abrasive wear, low friction properties, and improved temperature stability for the coatings. A literature survey on sputtering, plasma enhanced chemical vapor deposition (PECVD) and carbon based materials with a focus on a-C:H and Si-DLC coatings is given. This survey includes a brief overview of the 60 years history of DLC coating. In the second part of the thesis, the experimental set up for the layer preparation by a magnetron based deposition method and a basic description of the process are presented. Using sputtering from a solid SiC target as a source of the Si for the Si-DLC instead of the commonly used PECVD process with Si-containing precursors Si-DLC/a-C:H nanolayers were deposited at high deposition rates. For the coatings, the influence of the acetylene gas flow, the bias voltage, and the hydrogen and silicon concentration are discussed. Undoped a-C:H coatings with high indentation hardness above 40 GPa and very low abrasive wear rates of 0.6 x 10[-15] m[3]/(Nm) and low hydrogen content of about 11 at.% were deposited. Si-DLC/a-C:H nanolayer coatings with high hardness of 20 to 30 GPa and a high temperature stability up to 500 °C were prepared. For these nanolayer films low friction coefficients of 0.06 to 0.11 and high abrasive wear rates of > 2.5 x 10[-15] m3/(Nm) were achieved at high silicon contents above 15 at.%. On the other hand nanolayer coatings with low silicon contents of less than 10 at.% showed low wear rates below 1.7 x 10[-15] m3/(Nm) combined with higher friction coefficients of 0.12 to 0.15. In order to combine the low abrasive wear rate and the low friction coefficient at first a Si-DLC/a-C:H layer with low Si-concentration followed by a second layer with high Si-concentration was deposited. Due to the low surface free energy of Si-DLC coatings of 30 to 35 mN/m the wetting behavior for some lubricants may deteriorate. In this case a further optimization of the nanolayer system is required.
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Huang, Liyie. "Caractérisation et propriétés nanomécaniques des différents films DLC (diamond-like carbon)." Troyes, 2002. http://www.theses.fr/2002TROY0001.
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Cette étude porte sur les films DLC (diamond-like carbon). La charge critique lors d'un test de rayure augmente avec l'épaisseur inter-couche. Pour une épaisseur inter-couche donnée, la charge critique varie linéairement avec la dureté du film et son épaisseur. Le bas coefficient de frottement viendrait de la combinaison de la dureté élevée, de la faible rugosité et de la faible proportion de sp3. Dans le cas du fretting, le coefficient de frottement et l'humidité relative varient inversement. La proportion de sp3 augmente avec l'introduction de Si, ce qui fait monter la dureté, diminuer les frotements et augmenter la stabilité thermique de films a-SIC:H. L'augmentation de la fraction de sp3 dans les films a-C déposés par arc pulsé sous vide correspond bien à celles de la dureté et de la charge critique de rayure. Le fim a-C déposé par laser pulsé possède d'importantes contraintes internes. Un mécanisme de formation faisant appel à la théorie du flambement des coques est proposé. Le test de rayure des films DLC est divisé en 3 étapes : recouvrement élastique total, déformation plastique du film, délamination et écaillage du film. Cette résistance a d'abord été mesurée pour des films DLC sur substrat de Si. Il s'avère, à l'analyse élasto-plastique de la déformation au cours de la nanorayure, que la charge critique d'un film DLC sur Ti-6AI-4V est atteinte lorsque les déformations élastique et plastique sont comparables. L'analyse des expériences et de la morphologie de rayure nous permetttent de déduire que les mécanismes de rupture des films DLC sur Si et Ti-6AI-4V sont différents. Le relief des contraintes induits après rayure par le flambement a été modélisé afin de déterminer la charge de flambement critique. La rupture des films DLC sur Si, lors d'un test de rayure, a été modélisée en utilisant une analyse de flambement circulaire et ceci a été utilisé pour calculer énergie de rupture interfaciale et la résistance à la rupture.
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Maerten, Thibault. "Study of corrosion resistance of steel coated with DLC thin films." Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0105.
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Les couches minces DLC (Diamond Like Carbon) ont fait l’objet depuis près de 25 ans de recherches principalement axées sur leurs propriétés tribologiques et leur optimisation. Ces couches minces sont maintenant matures (TRL 9) et reconnues pour leur très fort potentiel de réduction du frottement et de l’usure. Elles sont employées par de nombreuses industries : les DLC sont des solutions technologiques courantes pour réduire les frottements dans les moteurs de voitures de grande série (pièces de distribution, axe de piston...). De nombreuses études scientifiques ont aussi identifié la grande inertie chimique de ces couches à base de carbone et d’hydrogène dans des environnements liquides agressifs (acides ou basiques) et contenant des chlorures. Basé sur ces constatations, l’utilisation de matériaux à base de DLC, pour des applications tribologiques nécessitant aussi une bonne résistance à la corrosion des pièces revêtues, est envisagée. Dans la plupart des applications visées, les pièces sont faites d’aciers présentant de hautes propriétés mécaniques (ex. : 100Cr6 – acier à roulements) mais ayant souvent une résistance à la corrosion très faible.Dans un contexte industriel, l'évaluation de la protection contre la corrosion des films minces est menée, la plupart du temps, avec des tests de brouillard salin neutre. En laboratoire, elle est principalement effectuée à l'aide de techniques électrochimiques. Dans le cadre de cette thèse, les deux techniques ont été utilisées et adaptées pour une évaluation cohérente et répétable de la résistance à la corrosion d’aciers revêtus de couches minces à base de carbone.Une évaluation des couches minces DLC existantes d’Oerlikon Balzers sur acier 100Cr6 a été faite. Cette évaluation a été réalisée à l'aide d'essais en brouillard salin neutre et d’essais électrochimiques classique telles que des courbes de polarisation (avec mesure préalable du potentiel de circuit ouvert). La corrosion du substrat en acier revêtu s'est avérée être variable en fonction des solutions de revêtement DLC testées. Dans tous les cas, une faible résistance à la corrosion des éprouvettes revêtues a été détectée. L’origine de la corrosion d’acier revêtu de couche minces DLC a été étudiée. Les défauts dus aux procédés de dépôt des couches minces DLC se sont révélés être les principaux responsables de la mauvaise tenue à la corrosion des substrats revêtus. Pour étudier ces défauts, une nouvelle configuration électrochimique a été développée. Elle combine l’utilisation de séquence de polarisation avec des observations in situ de la surface. Cette méthode a permis le suivi des phénomènes de corrosion au niveau d’un unique défaut de taille micrométrique. Des défauts artificiels, de tailles micrométriques, ont été réalisés dans un revêtement DLC à l'aide d’une sonde ionique focalisée, plus connue sous le sigle anglais FIB (Focused ion beam) afin d’étudier les mécanismes de corrosion ainsi que la taille minimale des défauts susceptible de conduire à la dégradation par corrosion du substrat. Enfin, sur la base des défauts précédents et de leur étude, de nouvelles solutions de revêtements innovantes ont été développées et évaluées. Ces solutions sont divisées en trois parties basées sur des concepts de dépôts recensés par la littérature : une approche multicouches du dépôts, une approche par couplage galvanique favorable et pour finir une approche par ajout d’une couche barrière à la corrosionSince almost 20 years, diamond-like carbon (DLC) thin films have been selected for tribological solutions mainly because of their excellent properties such as low coefficient of friction (five time less than bare steel in dry condition), high hardness (from 20 to 35 GPa for hydrogenated ones) and excellent wear properties (high abrasive wear resistance, preventing adhesive wear mechanisms). Most of the time, it has also been reported that DLC thin films have good intrinsic corrosion properties as they are chemically inert in sodium chloride solutions either in acid or basic environment. This has led to envision and evaluate the use of DLC thin films in tribological applications that also require complementary corrosion protection performances on coated parts (for instance: in aeronautic, in food industry for mechanical devices, in automotive for non-cosmetic part of structures). Typically, these coatings are deposited on steel alloys presenting high mechanical properties, such as tool steel or bearing ring steel that demonstrate poor or limited corrosion resistance.In an industrial context, the evaluation of corrosion protection of DLC thin films is presented, most of the time, with neutral salt spray tests or immersion tests, whereas at laboratory the evaluation would be mainly done using electrochemical techniques. In this work both techniques were used and also refined to specially fit the evaluation of such material. First, an evaluation of existing DLC based thin films from Oerlikon Balzers on mechanical steel were done as benchmark reference. This evaluation was conducted with NSS test and classic polarization experiments (open circuit voltage and linear sweep voltammetry). Corrosion of coated steel substrate was found to be variable depending on DLC coating solutions tested but, in all cases, a poor corrosion resistance of coated specimens was detected. Then origin of the poor corrosion protection aspect of DLC coating on steel substrate were studied. Defects coming from the deposition processes in coatings was found to be the main issues of poor corrosion results. To study such defects a new electrochemical setup was developed. It combines polarization experiments with in situ observations of a single defect at the surface. Artificial defects, with micrometric sizes, were milled in DLC coating using SEM-FIB to study the corrosion mechanisms as well as the minimum size of defects susceptible to lead to corrosion degradation. And finally based on the previous defects study, new and innovative coatings solutions were developed and evaluated. These solutions are divided in three parts based on coatings concepts found in literature: a multilayer approach, a galvanic coupling approach and a sealing layer approach
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Canaveira, David Rasteiro. "Desenvolvimento local de base comunitária: tendências e perspetivas a partir da Federação Minha Terra." Master's thesis, 2018. http://hdl.handle.net/10451/36228.
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A estratégia da CEE/UE de desenvolvimento das suas áreas rurais foi-se alterando ao longo do tempo, passando de uma visão produtivista, para uma de desenvolvimento a partir do local, baseada no aproveitamento dos recursos endógenos, motivada pelos excedentes de produtos agrícolas e outros problemas, internos e externos à Comunidade. Esta mudança de visão concretizou-se em 1991 com o surgimento do programa LEADER. Este programa, que decorreu em três fases, LEADER I, LEADER II e LEADER+, como previsto, acabou por passar a abordagem, em 2007-2013, e ser incluído nos PDR, financiado pelo recém-criado FEADER. No período de programação 2014-2020 o LEADER inspirou o surgimento de um novo instrumento de desenvolvimento local, o DLBC, que pode ser financiado de forma plurifundos e que está a ser aplicado em Portugal Continental a partir de vários programas, contando, no caso da vertente rural, com financiamento do FEADER, mas também de FEDER e FSE. Neste relatório de estágio, para além da descrição dessa evolução, apresenta-se a opinião de alguns associados da Federação Minha Terra, a partir de entrevistas, enquanto agentes do novo instrumento DLBC, sobre a sua implementação em Portugal e, a partir da mesma, apresentam-se recomendações/propostas para 2021-2027. São destacados, pelos responsáveis dos dez GAL que responderam às entrevistas, problemas relacionados com a excessiva pré-formatação das medidas dos programas, que resultou da pouca auscultação das ADL e outros agentes locais, a pouca flexibilidade para adaptar as estratégias às particularidades locais, a falta de coordenação entre os programas e fundos e as autoridades que os gerem, a burocracia, que no caso dos GAL do Continente é ainda maior pela existência de diferentes autoridades de gestão e entidades pagadoras, os atrasos causados pela multiplicação de processos de análise das candidaturas, ou a falta de informatização dos processos, sobretudo no caso dos GAL das RA. Os responsáveis dos GAL parecem concordar com as propostas da ELARD, do CESE e do Parlamento Rural Europeu para a criação de um único programa DLBC, com um único fundo financiador, composto por parte dos diferentes FEEI, uma só autoridade de gestão e uma única entidade pagadora. Apesar de válidas, estas propostas parecem pouco realistas e, portanto, apresentam-se outras recomendações/propostas, mais contidas.The EEC/EU strategy for the development of its rural areas has changed over time, from a productivist to a local-based development strategy, based on the exploitation of endogenous resources, motivated by the surplus of agricultural products and other problems, internal and external to the Community. This change of vision was achieved in 1991 with the emergence of the LEADER program. This program, which took place in three phases, LEADER I, LEADER II and LEADER +, was, in 2007-2013, included in the RDPs, funded by the newly created EAFRD. In the 2014-2020 programming period, LEADER has inspired the emergence of a new local development tool, the CLLD, which can be financed in a multifund way and which is being implemented in mainland Portugal from various programmes, meaning not only the EAFRD, but also the ERDF and the ESF. In this internship report, after the description of the evolution LEADER-CLLD, the opinion of some of the members of Minha Terra Federation is presented, based on interviews, as agents of the new CLLD instrument, on its implementation in Portugal and, inspired by them, we present recommendations and proposals for 2021-2027. The ten LAG people that responded to the interviews highlighted problems related to excessive pre-formatting of the programmes measures, which resulted from poor listening of LDAs and other local actors, lack of flexibility to adapt strategies to local particularities, lack of coordination between the programmes and funds and the authorities that manage them, the bureaucracy, which in the case of the LAGs of mainland Portugal is an even worse problem due to the existence of different managing authorities and paying agencies. Moreover, they referred the delays caused by the multiplication of the processes of analysis of the applications, or the lack of computerization of processes, especially in the case of the LAGs of the Autonomous Regions. The interviewed LAG members seem to agree with the proposals of ELARD, the EESC and the European Parliament for the creation of a single CLLD program with a single funding source composed of different ESIF, a single managing authority and a single paying entity. Although valid, these proposals appear to be unrealistic and therefore we present more contained recommendations / proposals.
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Oliveira, Célia Regina Marques. "Influência do W no comportamento à oxidação de revestimentos à base de carbono." Master's thesis, 2008. http://hdl.handle.net/10316/20308.
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Dissertação de Mestrado em Engenharia Mecânica apresentada à Faculdade de Ciências e Tecnologia da Universidade de CoimbraUma das desvantagens dos revestimentos à base de carbono, para aplicações mecânicas/tribologicos, é a baixa estabilidade térmica. Para temperaturas tão baixas como 300ºC ocorre perda de material, principalmente se o meio envolvente for uma atmosfera oxidante. A introdução de um metal poderá melhorar esta baixa resistência à oxidação sem prejudicar as sua propriedades mecânicas e/ou tribologicas. Este trabalho tem como objectivo o estudo da influência do W no comportamento à oxidação de revestimentos à base de carbono. Para tal formam fornecidas pelos orientadores 5 amostras de revestimentos divididas em duas séries. A primeira série de filmes, do tipo DLC é constituída por três tipos de amostras. A segunda série, de DLC dopado com tungsténio (W-DLC) contém dois tipos de amostras diferentes. Os revestimentos são testados a temperaturas compreendidas entre os 400 e 600ºC. Para a caracterização das amostras recorreu-se às técnicas de análise termogravimetrica, espectrometria de massa, difracção de raios-X e espectroscopia vibracional por Raman. Conclui-se com este estudo, que a introdução de tungsténio em DLC, faz com que este tenha maior resistência á oxidação e trabalhe a mais altas temperaturas, sem perder as suas características. Aumentando a sua temperatura de funcionamento em aproximadamente 100ºC.
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Loewen, Shauna. "Dlc-1 and Dlc-2 : studies of two RhoGAP genes in etoposide resistance and apoptosis." 2008. http://hdl.handle.net/1993/21077.
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Janez, Matej. "Electrical and Tribological Properties of DLC Coatings." Master's thesis, 2015. http://hdl.handle.net/10316/39083.
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Dissertação de Mestrado em Engenharia de Materiais apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra.DLC coatings have attracted interest of many researches due to their unique combination of properties. They are often used in various applications as protective coatings because of their excellent low friction and high wear resistance. However, little research has been done on the electric properties of DLC coatings and their possibilities in electric applications. The focus of this work was the analysis and comparison of electrical and tribological properties of selected commercial coatings in sliding electric contacts. In the thesis, the resistance, friction and wear behavior of four different coatings, which were selected based on their good electrical and tribological properties observed during preliminary testing, were evaluated and compared to steel at room temperature in dry reciprocating sliding mode and under different direct current conditions. Commercial DLC coatings selected for the analysis were Low Ti-DLC (5 at.%), High Ti-DLC (10 at. %), Low W-DLC (5 at.%) and High W-DLC (10 at.%). The tests were performed by simultaneously gathering friction and resistance data in the contact using a ball-on-disc tribometer and a voltage drop measuring setup. Optical microscopy and white light interferometry were used for the analysis of the wear scars. The results of the resistance measurements showed that all coatings conducted direct current. It was observed that higher doping element concentrations led to lower resistance of the contact. DLC – DLC contact also produced higher conductivity measurements compared to DLC – Steel contact. The conductivity of Steel – Steel contact was in a similar range as DLC – DLC contact. Static resistance was substantially lower than sliding resistance which confirms that sliding has a great effect on the conductivity of the contact. As expected, friction results displayed substantially lower friction coefficients for DLC – Steel and DLC – DLC contacts in comparison to Steel – Steel contact. The best material combination for electric application was High W-DLC – High W-DLC which exhibited very low electric resistance and friction coefficient with very low wear rate. The results gathered in this work indicate that DLC coatings have promising electric properties and show potential in future electric applications.
Os revestimentos DLC têm atraído o interesse da comunidade científica devido à sua combinação única de propriedades. São geralmente usados em várias aplicações sob a forma de revestimentos protetores uma vez que apresentam baixo atrito e elavada resistência ao desgaste. No entanto, existem poucas referências na literatura sobre valores de propriedades elétricas de revestimentos DLC e as suas potencialidades em aplicações eléctricas. O foco deste trabalho incidiu na determinação e análise das propriedades elétricas e tribológicas de revestimentos DLC comerciais. Neste trabalho foram estudados a resistividade, o atrito e a resistência ao desgaste de quatro revestimentos de DLC e de diferentes aços à temperatura por deslizamento alternativo a seco e diferentes condições de corrente continua. Os revestimentos DLC estudados neste trabalho foram Ti-DLC (5 e 10 % at.Ti ) e W-DLC (5 e 10 % at.W). Os testes realizados permitiram medir o coeficiente atrito e, simultaneamente, a resistividade no contacto, usando um tribómetro pino-disco e um equipamento de medição de tensão. A microscopia óptica e a interferometria de luz branca foram utilizads para a análise das pistas de desgaste. Os resultados das medições de resistividade mostraram que todos os revestimentos eram contudores eléctricos. Observou-se ainda que concentrações mais elevadas do elemento dopante conduziam a uma menor resistividade no contato. O contacto DLC – DLC também produziu medições de condutividade superior em comparação com o contacto DLC – aço. Os valores da resistividade estática são substancialmente inferiores aos obtidos por resistividade deslizante, confirmando-se assim que o deslizamento tem um grande efeito sobre a condutividade de contato. Tal como esperado, os valores do coeficientes de atrito obtidos para os pares DLC – aço e DLC – DLC são inferiors aos obtidos para o contato aço – aço. O par W-DLC – W-DLC com 10 % at. W foi o que apresentou maior potencial para aplicações elétricas, com muito baixos valores de resistividade elétrica e coeficiente de atrito e baixa taxa de desgaste. Os resultados obtidos neste trabalho indicam que os revestimentos DLC têm propriedades eléctricas promisoras, sendo potenciais materiais para futuras aplicações elétricas.
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ABDOLLAH, Mohd Fadzli Bin. "Impact Wear Mechanisms of DLC Coating." Thesis, 2011. http://hdl.handle.net/2237/16458.
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Silva, Carlos Wagner Moura e. "Desenvolvimento de recobrimentos autolubrificantes à base de carbono com teores variáveis de W e H para aplicação na indústria metalmecânica." Doctoral thesis, 2013. http://hdl.handle.net/10316/88693.
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Documentos apresentados no âmbito do reconhecimento de graus e diplomas estrangeirosRecobrimentos WC1-x/a-C:H, depositados via co-pulverização catódica de alvos de C com e sem pastilhas de W, em ambiente reativo, foram ensaiados com a técnica de deslizamento no plano tipo pino-sobre-disco (PSD) para avaliação do seu comportamento tribológico. Esses filmes foram desenvolvidos a partir da análise de recobrimentos à base de C (a-C, a-C:H e WC1-x/a-C) e otimizados em função dos teores de W e H (~10% at. e ~25% at., respectivamente). Os ensaios de PSD foram realizados sob condições previamente determinadas, buscando-se, com isso, permitir a avaliação da performance do filme hidrogenado em 3 condições: 30%, 50% e 80% de umidade relativa do ar (UR). Para tanto, foram otimizadas soluções salinas saturadas específicas para se obter os referidos valores UR e adaptações foram realizadas num equipamento convencional de ensaio PSD. Ensaios preliminares com os filmes WC1-x/a-C e a-C foram realizados para possibilitar a otimização dos parâmetros de ensaio para essa nova configuração de equipamento. Com esses ensaios de PSD em atmosfera controlada, foram estudadas tanto a influência do H e do W no comportamento friccional do filme quanto a influência da UR na resposta do recobrimento ao esforço de deslizamento. Quanto à influência do W e do H nos filmes, apesar de apresentarem valores de dureza com aproximadamente a mesma ordem de grandeza (H = 12 – 14 GPa), os filmes a-C, WC1-x/a-C e WC1-x/a-C:H apresentaram diferentes respostas friccionais quando testados em ambiente com 50% UR (0,22, 0,05 e 0,01, respectivamente). No geral, houve uma significativa diminuição do coeficiente de atrito com a hidrogenização do WC1-x/a-C ([0,01 – 0,05] contra [0,05 – 0,20] para os filmes não hidrogenados). Ensaios de espectroscopia Raman nas pistas de desgaste mostraram (para ambos os filmes) uma leve diminuição na razão ID/IG, sinalizando uma possível grafitização dos filmes nessa região de contato com o contracorpo. Foi observado também que, para os filmes com W incorporado, com o aumento da UR, houve um aumento também do coeficiente de atrito dos filmes, supostamente causado por um processo de oxidação do material de transferência (partículas do filme e do contracorpo). Análises de espectroscopia Raman do material de transferência aderido ao contracorpo (uma esfera aço) indicaram a presença de óxido de ferro nesse material.
WC1-x/a-C:H coatings were deposited by co-sputtering carbon targets without and with incrusted W-pellets. The coatings were tested in sliding mode in a pin-on-disk (POD) apparatus for the evaluation of their tribological properties. These films were developed based on preliminary studies on C-based coatings (a-C, a-C:H e WC1-x/a-C) being the optimization based on the analysis of the influence of W and H contents on the films properties. Optimum values were found to be ~10 at.% and ~25 at.%, respectively). POD tests of hydrogenated films were carried out in three relative humidity (RH) contents, 30%, 50% e 80% RH. To reach this goal, POD apparatus was modified to allow working in controlled atmospheres created by specific and optimized saturated saline solutions, to achieve the desired RH values. The optimization of the test conditions in the modified POD equipment was performed through preliminary tests with WC1-x/a-C e a-C coatings. The influence of both H and W contents on the friction coefficient of the film was studied. Similarly, the influence of RH values on the sliding behaviour was analysed. Although a-C, WC1-x/a-C e WC1-x/a-C:H coatings had approximately the same hardness (H = 12 – 14 GPa), they showed different frictional behaviour when tested in 50% RH environment (0.22, 0.05 e 0.01, respectively). Generally, a significant reduction of the friction coefficient was achieved in hydrogenated WC1-x/a-C film ([0,01 – 0,05] against [0,05 – 0,20] for non-hydrogenated films). Raman analyses of the worn tracks showed (in both cases) a small reduction of ID/IG ratio, suggesting film graphitization in the contact zone against the counterbody. For the coatings with incorporated W, there was an increase of the friction coefficient with increasing RH values, as a result of the oxidation of the transfer material either from the film or the counterbody. Raman analysis of the transfer material adherent to the counterbody (steel ball) showed the presence of iron oxide.
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Wang, Shii Haw, and 王璽皓. "Tribology Potential of DLC Coated Milling Inserts." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/05491642114000790287.
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碩士國立成功大學
機械工程學系
86
Tribology potential of diamond-likecarbon(DLC) coatings was discussedin this thesis. Before milling experiments, DLC coatings were coated ontungsten carbide-cobalt(WC) alloy milling inserts. The DLC coatings aremetal doped diamond-like carbon(Me- C:H). There were metals doped inDLC coatings, titanium and chromium. The workpiece used in experimentsis 7075 aluminum alloy.Experiments were carried out under dry andcoolant conditions on NC machining center. TiN, TiCN, CrN and CrCNcoatings were also compared with DLC coatings in experiments.The experiment results are shown as follow: Increase the thickness of DLCcoatings conduce to high residual stress and peel off the coating layers.Increasing the doping metal may meliorate this situation. Sp2 and sp3 carbonbonds in DLC coatings were identified by Raman test. On the other hand,the DLC coatings used in experiments contain tetrahedron structure. In the first step of milling test, we used the confirmation and analysesrecommended by Taguchi method to optimizea condition for milling. Themost significant factor among the four factors in this experiment(thicknessof DLC coating, milling speed, milling depth and feed rate)is the thicknessof DLC coatings, so we focus the parameters on coating conditions in the later.As a result, the best thickness of DLC coatingis 2.5μm.In the case of 3.5μm coatings, the coating layers were peeled off. For different dopingmetals, titanium series were better than chromium series in flank wear. Incoolant condition, the DLC coatings performed nice tribology potential.This result indicated that the DLC coatings used in this experiment arestable in humid environment. When milling S45C, the high feed ratecondition in milling test made the tool fractured, but the DLC coatings stillreduce the degree of fracture.