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1
Hung, Jacky. "The Cystine Binding Protein (BspA) of Lactobacillus fermentum BR11." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16146/1/Jacky_Hung_Thesis.pdf.
Abstract:
BspA was first identified on the basis of being the major constituent of 5 M LiCl washes of whole Lactobacillus fermentum BR11 cells. The bspA gene is encoded within a putative ATP-binding cassette (ABC) transport operon, and sequence analysis revealed that it is a member of the family III solute binding proteins. Unlike the majority of solute binding proteins from Gram-positive bacteria, BspA is not tethered to a lipid anchor in the cell membrane, and hence is not a lipoprotein. Extraction of BspA with concentrated salt solutions such as 5 M LiCl is consistent with the notion that electrostatic interactions are responsible for securing it to the L. fermentum BR11 cell.
L. fermentum PNG201 is a BspA negative mutant strain created by disrupting bspA. This strain was shown to be incapable of cystine uptake. Thus, the genetic and biochemical evidence strongly suggests BspA is a cystine binding protein of an ABC transporter. Measurement of the binding affinity between BspA and L-cystine has confirmed high affinity binding (dissociation constant is 0.2 µM), and high specificity (over 100-fold excess of non-target amino acids did not disrupt BspA / L-cystine binding). In addition, collagen did not appear to affect BspA/cystine binding, indicating extracellular matrix (ECM) binding capacity noted by other researchers may be unrelated to amino acid binding.
An interesting phenotypic characteristic of L. fermentum PNG201 is its apparent increased sensitivity to oxygen and the superoxide-generating chemical - paraquat compared to the parent L. fermentum BR11 strain. Catalase supplemented aerobic cultures of L. fermentum BR11, and L. fermentum PNG201 were protected from oxidative stress, suggesting hydrogen peroxide is responsible for the observed oxidative stress. It was found that addition of cystine to aerobic cultures of L. fermentum BR11 or L. fermentum PNG201 protected both strains from oxidative stress, with L. fermentum BR11 able to utilize smaller concentrations of cystine compared to L. fermentum PNG201. Detection of hydrogen peroxide in aerobic cultures of L. fermentum BR11 and L. fermentum PNG201 confirmed the production of hydrogen peroxide is responsible for causing oxidative stress. The BspA mutant strain L. fermentum PNG201 consistently produced more hydrogen peroxide per optical density compared with the wild type, indicating it overproduced hydrogen peroxide. When 0.4 mM hydrogen peroxide has been accumulated by growing cell cultures, both L. fermentum BR11 and L. fermentum PNG201 enters stationary phase, suggesting both strains have a similar sensitivity to hydrogen peroxide.
Small epitopes from the HIV gp41 protein and the Chlamydia psittaci major outer membrane protein have been successfully displayed on the cell surface of L. fermentum BR11 as fusion proteins to the BspA molecule. However, the capability of BspA in exporting larger polypeptides has not been tested. In this study, the large extracellular enzyme - glucosyltransferase (GtfJ) from Streptococcus salivarius ATCC 25975 was fused to BspA to demonstrate that this expression system is capable of exporting large functional enzymes to the cell surface of L. fermentum BR11. The native GtfJ is 160kDa in size and also contained an export signal, which was deleted in the cloning process and replaced with BspA, resulting in a fusion protein of 175kDa. Export of the BspA/GtfJ fusion protein is dependant entirely on BspA's export signal. Recombinant enzyme expression and glucosyltransferase activity were detected by measuring the glucan formed by sonicated cell extracts in acrylamide gels. Enzyme activity measurements on whole cells has revealed the recombinant Lactobacillus was incorporating 20-40 nmol of sucrose-derived-glucose into glucan per ml of cell culture per OD unit, which is comparable to activity levels exhibited by the native bacteria that expressed this enzyme. Comparison of GtfJ enzyme activity between whole cells and sonicated cell extracts of recombinant L. fermentum confirmed the extracellular location of BspA/GtfJ as enzyme activity was essentially identical.
2
Hung, Jacky. "The Cystine Binding Protein (BspA) of Lactobacillus fermentum BR11." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16146/.
Abstract:
BspA was first identified on the basis of being the major constituent of 5 M LiCl washes of whole Lactobacillus fermentum BR11 cells. The bspA gene is encoded within a putative ATP-binding cassette (ABC) transport operon, and sequence analysis revealed that it is a member of the family III solute binding proteins. Unlike the majority of solute binding proteins from Gram-positive bacteria, BspA is not tethered to a lipid anchor in the cell membrane, and hence is not a lipoprotein. Extraction of BspA with concentrated salt solutions such as 5 M LiCl is consistent with the notion that electrostatic interactions are responsible for securing it to the L. fermentum BR11 cell. L. fermentum PNG201 is a BspA negative mutant strain created by disrupting bspA. This strain was shown to be incapable of cystine uptake. Thus, the genetic and biochemical evidence strongly suggests BspA is a cystine binding protein of an ABC transporter. Measurement of the binding affinity between BspA and L-cystine has confirmed high affinity binding (dissociation constant is 0.2 µM), and high specificity (over 100-fold excess of non-target amino acids did not disrupt BspA / L-cystine binding). In addition, collagen did not appear to affect BspA/cystine binding, indicating extracellular matrix (ECM) binding capacity noted by other researchers may be unrelated to amino acid binding. An interesting phenotypic characteristic of L. fermentum PNG201 is its apparent increased sensitivity to oxygen and the superoxide-generating chemical - paraquat compared to the parent L. fermentum BR11 strain. Catalase supplemented aerobic cultures of L. fermentum BR11, and L. fermentum PNG201 were protected from oxidative stress, suggesting hydrogen peroxide is responsible for the observed oxidative stress. It was found that addition of cystine to aerobic cultures of L. fermentum BR11 or L. fermentum PNG201 protected both strains from oxidative stress, with L. fermentum BR11 able to utilize smaller concentrations of cystine compared to L. fermentum PNG201. Detection of hydrogen peroxide in aerobic cultures of L. fermentum BR11 and L. fermentum PNG201 confirmed the production of hydrogen peroxide is responsible for causing oxidative stress. The BspA mutant strain L. fermentum PNG201 consistently produced more hydrogen peroxide per optical density compared with the wild type, indicating it overproduced hydrogen peroxide. When 0.4 mM hydrogen peroxide has been accumulated by growing cell cultures, both L. fermentum BR11 and L. fermentum PNG201 enters stationary phase, suggesting both strains have a similar sensitivity to hydrogen peroxide. Small epitopes from the HIV gp41 protein and the Chlamydia psittaci major outer membrane protein have been successfully displayed on the cell surface of L. fermentum BR11 as fusion proteins to the BspA molecule. However, the capability of BspA in exporting larger polypeptides has not been tested. In this study, the large extracellular enzyme - glucosyltransferase (GtfJ) from Streptococcus salivarius ATCC 25975 was fused to BspA to demonstrate that this expression system is capable of exporting large functional enzymes to the cell surface of L. fermentum BR11. The native GtfJ is 160kDa in size and also contained an export signal, which was deleted in the cloning process and replaced with BspA, resulting in a fusion protein of 175kDa. Export of the BspA/GtfJ fusion protein is dependant entirely on BspA's export signal. Recombinant enzyme expression and glucosyltransferase activity were detected by measuring the glucan formed by sonicated cell extracts in acrylamide gels. Enzyme activity measurements on whole cells has revealed the recombinant Lactobacillus was incorporating 20-40 nmol of sucrose-derived-glucose into glucan per ml of cell culture per OD unit, which is comparable to activity levels exhibited by the native bacteria that expressed this enzyme. Comparison of GtfJ enzyme activity between whole cells and sonicated cell extracts of recombinant L. fermentum confirmed the extracellular location of BspA/GtfJ as enzyme activity was essentially identical.
3
Soutar, Colin. "Optical information processing using photorefractive BSO." Thesis, Abertay University, 1991. https://rke.abertay.ac.uk/en/studentTheses/a757b4d3-6c1e-4600-aed8-430e7078c6c5.
Abstract:
Several optical information processing tasks are implemented using photorefractive BSO as a dynamic holographic medium. The physical basis for the mechanism which allows the implementation of these devices is studied. The properties of BSO which make it particularly attractive as a processing medium are highlighted, and experimental results are presented to demonstrate its practical limitations. An extensive study is presented of the influence of optical bias on the grating formation characteristics. This leads to a documentation of the optimum conditions for transient enhancement of a beam diffracted from such a grating. This transient enhancement can be controlled to provide ideal characteristics for the implementation of transient devices such as a novelty filter. A novelty filter utilising this transient enhancement is subsequently demonstrated. It exhibits good temporal discrimination through the choice of suitable external optical conditions, and the use of digital thresholding. The overall device operates at T.V. frame rates. Results are also presented of various optical correlators using BSO. These include the optical intensity correlator. The unique properties of the intensity correlator are stressed by practical demonstration. Specifically, the relative intolerance of the intensity correlator (compared with coherent correlators) to the position of the various components is demonstrated. Also, the spatially incoherent readout light allows the use of a low-optical quality liquid crystal television (LCTV) as a low-cost spatial light modulator. Output results are then presented from the correlator using the LCTV as a dynamic readout device. This provides an updateable hologram as the reference of the correlator which is interrogated at frame rates by the LCTV. Finally, the temporal discrimination of the novelty filter is combined with the character recognition ability of the intensity correlator. This produces an optical processor which will recognise a particular object but will only register it at the output stage when it is moving.
4
Cook, Nicholas James. "Properties and processing applications of photoreactive BSO." Thesis, University of Abertay Dundee, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242115.
5
Forsyth, Robert Bruce. "A study of auto-anti-idiotypes to BSA." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/27425.
Abstract:
In order to study the idiotypic relationships between the antibody populations produced in different species during normal immune responses to ordinary protein antigens, we raised immune sera in mice and chickens using three protein antigens: Bovine serum albumin (BSA), keyhole limpet hemocyanin (KLH) and diphtheria toxoid (DT). An avidin-biotin ELISA was used to measure idiotypic binding between antibody populations from these sera. We found that the chicken sera contained auto-anti-idiotypes (AAI) against antigen specific antibodies which were present in the same serum and which co-purified with those antibodies on antigen-sepharose columns. These AAI were present in secondary response chicken anti-BSA serum at levels comparable to that of the anti-BSA antibody. The chicken AAI also react specifically with Ids in mouse anti-BSA serum. Mouse anti-BSA serum completely inhibited the binding between the chicken Id and AAI. This similarity between the idiotypes of whole populations of antibodies produced in two distantly related species, in the absence of any manipulation with idiotypic or anti-idiotypic reagents, suggests that the AAI detected in this way are internal image antibodies. It indicates there is positive selection for such auto-anti-idiotypes to be internal images.Science, Faculty of
Microbiology and Immunology, Department of
Graduate
6
Wang, Zhao Qi. "Real-time optical intensity correlation using photorefractive BSO." Thesis, Abertay University, 1995. https://rke.abertay.ac.uk/en/studentTheses/f1330975-bc23-4532-ac7b-8aeb9cad8c81.
Abstract:
Real-time optical intensity correlation using a photorefractive BSO crystal and a liquid crystal television is implemented. The underlying physics basis is considered, some specific techniques to improve the operation are proposed, and several optical pattern recognition tasks are achieved. Photorefractive BSO is used as the holographic recording medium in the real-time intensity correlator. To improve the dynamic holographic recording, a moving grating technique is adopted. The nonlinear effects of moving gratings at large fringe modulation are experimentally investigated, and are compared with numerical predictions. Optical bias is adopted to overcome the difficulty of a large drop in the optimum fringe velocity with moving gratings. The effects of optical bias on the optimum fringe velocity and on the diffraction efficiency are studied. To overcome the inherent drawback of low discrimination of intensity correlation in optical pattern recognition, real-time edge-enhanced intensity correlation is achieved by means of nonlinear holographic recording in BSO. Real-time colour object recognition is achieved by using a commercially available and inexpensive colour liquid crystal television in the intensity correlator. Multi-class object recognition is achieved with a synthetic discriminant function filter displayed by the Epson liquid crystal display in the real-time intensity correlator. The phase and intensity modulation properties of the Epson liquid crystal display are studied. A further research topic which uses the Epson liquid crystal display to realize a newly designed spatial filter, the quantized amplitude-compensated matched filter, is proposed. The performance merits of the filter are investigated by means of computer simulations.
7
Lin, Chenting. "Single crystal growth and characterization of BSO (Bi12SiO20)." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11647.
8
Hecker, Dominic, Daniel Gloess, Peter Frach, and Gerald Gerlach. "Electrospray ionization deposition of BSA under vacuum conditions." SPIE, 2015. https://tud.qucosa.de/id/qucosa%3A35187.
Abstract:
Vacuum deposition techniques like thermal evaporation and CVD with their precise layer control and high layer purity often cannot be applied for the deposition of chemical or biological molecules. The molecules are usually decomposed by heat. To overcome this problem, the Electrospray ionization (ESI) process known from mass spectroscopy is employed to transfer molecules into vacuum and to deposit them on a substrate. In this work, a homemade ESI tool was used to deposit BSA (Bovine serum albumin) layers with high deposition rates. Solutions with different concentrations of BSA were prepared using a methanol:water (MeOH:H2O) mixture (1:1) as solvent. The influence of the substrate distance on the deposition rate and on the transmission current was analyzed. Furthermore, the layer thickness distribution and layer adhesion were investigated.
9
Kawamura, Keiichi. "BSO - Broad System of Ordering: an international bibliography." K. Kawamura, 2011. http://hdl.handle.net/10150/129413.
Abstract:
The book was originally prepared for publishing in print. The author has decided to make it available as an online editionThis bibliography,compiled by K. Kawamura, lists about 270 references to BSO ranging from 1973 to 2010. The number of languages covered in the bibliography is 19 in all: Arabic, Chinese, Croatian, Czech, Dutch, English, French, German, Hungarian, Italian, Japanese, Korean, Lithuanian, Polish, Portuguese, Russian, Slovak, Slovenian and Spanish. Every item has English abstract and/or annotation. Items are arranged in systematic order, and cross-references among related items as well as author and language indexes complement the systematic arrangement.
10
Carvalho, Jesiel Freitas. "Crescimento e caracterização de monocristais fotorreativos: BSO e BTO." Universidade de São Paulo, 1994. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-14012009-093345/.
Abstract:
Neste trabalho crescemos monocristais de Bi12SiO20 (BSO) e de Bi12TiO20 (BTO). Os cristais de BSO foram crescidos pela técnica de Czochralski a partir da fase líquida com composição molar 6Bi2O3:1SiO2. Os melhores resultados foram obtidos para taxas de puxamento entre 1 e 2,5mm/h, a velocidade de rotação foi mantida constante em 20rpm. Os cristais de BTO foram crescidos pelo método top-seeded solution Growth (TSSG) a partir da composição molar 10Bi2O3:1SiO2, com taxas de puxamento menores que 0,3mm/h e velocidade de rotação entre 16 e 30 rpm. A qualidade dos cristais foi avaliada utilizando microscopia óptica e eletrônica, corrosão seletiva e raios-x. Por microscopia óptica identificamos os defeitos macroscópicos e discutimos sua natureza e possíveis causas. Utilizando a técnica de ataque químico seletivo, analisamos a morfologia das figuras de ataque e estimamos a densidade de deslocações. Visando identificar defeitos de estequiometria, fizemos medidas de composição por microanálise eletrônica. Para a caracterização cristalográfica, calculamos o parâmetro de rede por difração de raios-x usando o método do pó e confirmamos a estrutura cristalográfica através do método de Rietveld. E, ainda, medimos a atividade óptica que é uma constante característica dos cristais.In this work we grew Bi12SiO20 (BSO) and Bi12TiO20 single crystals. The BSO crystals have been grown from the melt composition of 6Bi2O3:1SiO2 by the Czochralski method. The best results were obtained at pulling rates from 1 to 2.5m/h, the rotation rate of 20rpm was constant. The BTO crystals have been grown by the top-seeded solution growth technique from a 10Bi2O3:1SiO2 solution with pulling rates less than 0.3mm/h and rotation rates from 16 to 30rpm. The crystal quality was examined by optical and scanning electron microscopy, selective etching, and x-ray diffraction. We identified the macroscopic defects by optical microscopy and discussed their nature and probable origin. Using selective etching, we analyzed the etching pits morphology and evaluated the dislocation density. To identify stoichiometric defects, composition measurements by electron probe microanalysis were made. To obtain crystallographic characterization, we calculated the cell parameter by powder method x-ray diffraction and used the Rietveld method to verify the crystallographic structure. And, also, we measured the optical activity, a constant of the crystals.
11
Jeffrey, Philip Michael. "Enhancement of the photorefractive properties of BSO and BaTiO3." Thesis, University of Southampton, 1994. https://eprints.soton.ac.uk/399145/.
Abstract:
The fundamental properties of photorefractive crystals have been extensively investigated for nearly the past two decades. Two significant photorefractive crystals that have been the subject of investigation are bismuth silicon oxide (BSO) and barium titanate (BaTiO3). The aim of this thesis was to find ways to enhance the photorefractive properties of BSO and BaTiO3 to further research into production of a practical phase conjugate device with a high diffraction efficiency, fast response time, operation in the infra-red for laser diode compatibility, stable output and miniaturisation of crystal volume. A technique to enhance the diffraction efficiency of BSO by a factor x100 has been successfully demonstrated and waveguides have been successfully fabricated in BaTiO3 through H+ implantation. The losses of these waveguides have been minimized by implanting over a range of doses and measuring the observed losses. Both self pumped and mutually pumped phase conjugators have been successfully demonstrated in these BaTiO3 waveguides. However, the remaining concern is that BaTiO3 crystals in both bulk and waveguide geometries exhibit instabilities which are undesirable for stable phase conjugate output. Much speculation has been given to the nature of the instabilities, but it is shown for the first time, that under certain conditions the phase conjugate output makes a transition from stable to chaotic behaviour. Regions of stable operation have been identified.
12
Gouveia, Duarte Domingos. "Influência da oxidação da BSA na sua digestão proteolítica." Master's thesis, Universidade de Aveiro, 2012. http://hdl.handle.net/10773/11360.
Abstract:
Mestrado em Bioquímica - Métodos BiomolecularesAs modificações oxidativas em proteínas são processos comuns em organismos aeróbios. A compreensão dos processos envolvidos na iniciação e desenvolvimento destas modificações, assim como da sua natureza, poderá contribuir para a elucidação do processo de envelhecimento, assim como de algumas patologias a ele associadas. A análise de proteínas oxidadas é comummente feita com base em técnicas proteómicas de identificação e quantificação utilizando a espectrometria de massa. A identificação é feita normalmente utilizando a análise dos péptidos resultantes de digestões proteolíticas das proteínas. No entanto, existem muitas limitações impostas pelas modificações oxidativas na utilização destas técnicas. De entre elas, a digestão enzimática a que as proteínas são sujeitas antes da análise por MS, representa talvez a que necessita de mais atenção. A ocorrência de clivagens falhadas poderá levar à impossibilidade de efetuar identificações e quantificações eficazes. Neste trabalho pretendeu-se avaliar a influência que a oxidação da albumina do soro bovina (BSA) teria na sua digestão proteolítica. Para tal procedeu-se à oxidação da BSA recorrendo-se à reação de Fenton durante vários tempos de incubação. Analisou-se posteriormente o grau de oxidação avaliando as concentrações de proteína por SDS-PAGE, os níveis de carbonilos em solução por espectrofotometria e na banda da BSA por Western Blot. A eficiência da digestão proteolítica foi avaliada por espectrometria de massa com base nas taxas de cobertura obtidas em pesquisas dos espectros em bases de dados. No final, concluiu-se que a proteína sofre uma fragmentação crescente ao longo do processo de oxidação, em consonância com um aumento crescente dos níveis de carbonilos. Pela análise da eficiência da digestão, não se verificaram diferenças entre as digestões de amostras não oxidadas e oxidadas, levando-nos a concluir que a oxidação da proteína não influencia a sua digestão com tripsina ou proteinase K.
Protein oxidative modifications are a common process in aerobic organisms. The comprehension of the processes involved in the initiation and development of these modifications can give us better insights of some common pathologies associated with the aging process. The analysis of oxidized proteins is normally based on mass spectrometric proteomic methodologies. The identification is performed with a shotgun strategy, where the protein mixture is submitted to proteolysis and the resulting peptides are analysed on a mass spectrometer. However, caution should be taken in applying these techniques in the field of protein oxidation. Oxidative modifications impose several limitations to protein identification and quantification due to the several structural and chemical modifications that occur. The enzymatic proteolysis applied before MS analysis is probably the step where one has to be especially careful, due to the occurrence of missed cleavages that difficult an efficient quantification. In this work, it was evaluated the efficiency of the proteolytic digestion with trypsin and proteinase K on oxidized bovine serum albumin (BSA). The protein was submitted to a metal-catalysed oxidation system for several incubation periods and the extent of oxidation was analysed by determining its concentration on SDS-PAGE, and the carbonyl levels by spectrophotometry and Western blot. In order to evaluate the digestion efficiency a mass spectrometry analysis based on sequence coverage of the protein after database search was carried out. We concluded that the protein suffers fragmentation during the oxidative reaction along with a substantial raise of amino acid residues side chain carbonyl levels. The digestion efficiency of the control and oxidized sample was similar, leading us to conclude that the oxidative state of the protein wasn’t an obstacle to the proteases.
13
Sá, Antonio Wellington Lima de. "Fabricação e caracterização de filmes automontados de PAH/BSA." reponame:Repositório Institucional da UFABC, 2010.
14
Ferreira, Ernando Silva. "Interação da proteína albumina do soro bovino (BSA) com substratos sintéticos." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-22072010-102300/.
Abstract:
A interface formada por materiais biológicos e materiais sintéticos tem grande importância em aplicações biomédicas, tais como o desenvolvimento de biomateriais para implantes médicos, que tem como processo essencial a deposição de proteínas na superfície dos biomateriais, e ainda não é bem compreendido no nível molecular. Algumas proteínas sofrem mudanças conformacionais após a adsorção na interface sólido-líquido, afetando suas funções ou propriedades, e algumas técnicas podem medir mudanças conformacionais em interfaces sólido. É possível estudar a fluorescência intrínseca de proteínas: a posição do máximo na faixa espectral da fluorescência, a eficiência quântica e o tempo de vida de fluorescência são indicadores de mudanças no ambiente local de grupos de moléculas de proteína fluorescente. Por outro lado, Nanopartículas de ouro têm atraído muita atenção pela sua afinidade com materiais biológicos e suas propriedades ópticas. Nesta tese, estudamos a viabilidade de substratos de vidro, quartzo, mica e ITO (óxido de índio e estanho) modificado com quitosana, phtalocyanines (Ni, Fe e Ni) e poli(alilanina hidroclorada) (PAH) na adsorção de BSA em forma dos filmes produzidos pela técnica camada por camada. O sistema foi estudado por UV-Vis e espectroscopia de fluorescência estática e resolvida no tempo. A caracterização morfológica dos filmes foi realizada por microscopia de força atômica e microscopia óptica. Os resultados mostram que os filmes de BSA / HAP cresceram com eficiência quatro vezes maior do que os filmes feitos de quitosana, que o quartzo tem a melhor janela de trabalho de UV-vis e há uma relação entre o pH da BSA e o tempo vida de fluorescência do filme resultante. As nanopartículas de ouro foram produzidas pela redução química e estabilizada por quatro diferentes métodos. O crescimento das nanopartículas foi monitorado por UV-vis spectroscopy. A carga de superfície das nanopartículas e da BSA foi estimado em vários valores de pH por medidas de potencial zeta. Os resultados indicaram que as nanopartículas têm cargas negativas na faixa de pH estudada. Soluções de BSA foram preparadas em diferentes valores de pH, e levadas para interagir com as nanopartículas de ouro. Os dados de supressão de fluorescência da BSA mostraram uma maior afinidade da BSA com nanopartículas estabilizadas com sacarose, com pH próximo do ponto isoelétrico (IP) estimado para BSA.The interface formed by biological materials and synthetic materials has great importance in biomedical applications such as the development of biomaterials for medical implants, which has as an essential process of protein adsorption on the surface of biomaterials, and is not yet well understood in the molecular level. Some proteins undergo conformational changes after adsorption at solid-liquid interfaces, affecting their functions or properties, and few techniques can measure conformational changes in solid interfaces. It is possible to study the intrinsic fluorescence of proteins: the position of the maximum in the spectral range of fluorescence, the quantum efficiency and lifetime of fluorescence are indicators of change in the local environment of fluorescent groups of protein molecules. On the other hand, gold nanopartículas have attracted much attention for its affinity with biological materials and their optical properties. In this thesis we study the feasibility of glass substrates, quartz, mica and ITO (Indium tin oxide) modified with chitosan, phtalocyanines (Ni, Fe and Ni) and poly (allylamine hydrochloride) (PAH) on the adsorption of BSA in the form of films produced by the layer by layer technique. The system was studied by UV-Vis and static and time-resolved fluorescence spectroscopy. Morphological characterization of the films was performed by atomic force microscopy and optical microscopy. The results indicate that the films of BSA/PAH grew with efficiency four times greater than the films made of chitosan, that the quartz has the best working window for UV-vis and there is a relationship between the pH of the BSA and lifetime of fluorescence of the resulting film. Gold nanoparticles were produced by chemical reduction and stabilized by four different methods. The growth of nanoparticles was monitored by UV-vis spectroscopy. The surface charge of nanoparticles and the BSA was estimated at various pH values by zeta potential measurements. The results indicated that the nanoparticles have negative charges in the pH range studied. BSA solutions were prepared at various pH values, were taken to interact with gold nanoparticles. Fluorescence quenching data of BSA showed a greater affinity of the BSA with nanoparticles stabilized with sucrose, at pH near the isoelectric point (IEP) estimated for BSA.
15
Istanbullu, Alexander. "Prestandajämförelse av textbaserade och binära dataformat för AJAX." Thesis, Högskolan i Skövde, Institutionen för kommunikation och information, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-8509.
Abstract:
Introduktionen av AJAX har möjliggjort skapandet av dynamiska webbapplikationer på Internet. Dessa dynamiska webbapplikationer bygger på att skicka data mellan klient och server med hjälp av asynkrona förfrågningar. Detta görs med hjälp av ett serialiseringsformat som används för att kompaktera data och möjliggöra kommunikation mellan olika programmeringsspråk. Binära serialiseringsformat har konsistent visat sig prestera bättre än de textbaserade alternativen på plattformar som tillåter binär transport av data. AJAX är en plattform som endast tillåter textbaserad transport av data. Detta arbete syftar till att jämföra prestandan av textbaserade och binära serialiseringsformat för AJAX med hjälp av bland annat round-trip time. Arbetet har utförts genom att skapa en webbapplikation som utför prestandamätningar med hjälp av olika datamängder med varierande storlek och innehåll. Resultaten visar att binära serialiseringsformat endast skulle kunna vara ett tänkbart alternativ när det rör sig om webbapplikationer som skickar mycket sifferdominant data.
16
Ostrowski, Adam. "Characterisation of the localisation and function of the Bacillus subtilis YuaB protein during biofilm formation." Thesis, University of Dundee, 2012. https://discovery.dundee.ac.uk/en/studentTheses/29fe0d1b-a010-4cb9-8698-7f393b6e08ee.
Abstract:
Bacteria can actively communicate and interact with each other to establish multicellular communities. Many of these processes involve functional differentiation of cells into specialised subpopulations by expression of varying genetic programmes. This leads to division of labour between the arising subpopulations of cells in the community. One type of such community is the biofilm, which is composed of microbial cells enclosed in a biopolymeric matrix. Such biofilms can be formed in a large range of environments from sea beds to animal tissues. Bacillus subtilis is a soil dwelling Gram-positive rod that was shown to closely interact with plants and establish a protective symbiosis by formation of biofilms on the roots. The biofilm matrix synthesised by B. subtilis is composed of the exopolysaccharide, for which the chemical structure is not yet established, and a protein TasA that forms amyloid-like fibres spanning between the cells and anchored to the cells by an accessory protein TapA. A third protein of unknown function, YuaB, has also been shown to be necessary for establishment of a biofilm. However, the mechanism of function for YuaB has not been elucidated. The data presented in this report focus on the role played by YuaB during formation of the biofilm. By analysis of cell differentiation patterns YuaB was shown to be required for maturation of the biofilm. The localisation of YuaB is identified in two “subtypes” of biofilm, a biofilm pellicle floating on the air-liquid interface and complex colonies formed on solid surfaces. This is achieved using a combination of biofilm fractionation combined with Western blotting and a newly developed method for immuno-fluorescent labelling of biofilm proteins. YuaB acts in synergy with the exopolysaccharide and TasA, as both components of the biofilm matrix are synthesised in the absence of YuaB but the biofilm is not made. The initial structural characterisation of YuaB is presented based on in silico predictions and physiological and biophysical analysis of the mutations introduced into the sequence of YuaB. The experimental data is concluded with a hypothesis that YuaB forms a hydrophobic protective layer necessary for support of the structure of the matured biofilm.
17
Glascock, Abigail L. "Evolution and Niche Specialization of Microbial Taxa in Vaginal Infection and Pregnancy." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5385.
Abstract:
The vaginal microbiome plays an important role in reproductive health and pregnancy. It has coevolved with humans and has direct effects on reproductive success, rendering selective pressure more pronounced at this site. Herein, we probe coevolution of the vaginal microbiome using a systems-level approach. In Chapter 2, we examine the evolutionary trajectory of two vaginal Veillonellaceae phylotypes evolved from an ancestral gastrointestinal lineage to inhabit the vaginal niche. We present evidence of their divergence and subniche specification and describe their differential associations with vaginal infection and pregnancy. In Chapter 3, we identify ten bacterial taxa, predicted to contribute to the underlying pathology of the sexually transmitted infection trichomoniasis. This ‘pathogroup’, which has undergone conditional differentiation to thrive in the presence of T. vaginalis, includes previously undescribed organisms and putative symbionts. Lastly in Chapter 4, we present the first characterization of BspA proteins, multi-modal virulence factors, in the vaginal microbiome and provide evidence of their extensive horizontal transfer across diverse microbial lineages. We use homology modeling to demonstrate conservation of structural and functional characteristics of these proteins between diverse bacterial taxa and identify structural variants, potentially indicative of subtypes. These findings further our understanding of the contributions of individual bacterial species, bacterial communities and virulence determinants in the health and disease. Furthermore, they lay the groundwork for future work characterizing coevolution of the human vaginal microbiome. These systems-level approaches will facilitate synergy between broad and reductive approaches and inform strategies for modulation of the microbiome and development of more effective therapeutics.
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Sales, Elisa Morandé. "Estudo das interações proteína-proteína, proteína-membranas e proteína-agentes desnaturantes por espalhamento de raios-X a baixos ângulos." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-22052018-152931/.
Abstract:
Neste trabalho estudamos por espalhamento de raios-X a baixos ângulos (SAXS) quatro diferentes sistemas de interesse biológico. Visamos investigar a auto-agregação de proteínas e de complexos proteicos que darão origem a fibras amilóides, interação proteína-proteína, simulando ambientes altamente concentrados, interação proteína-membrana simulando vesículas de matriz extracelular (MVs) de sistemas de biomineralização e interações proteína-agentes desnaturantes. No caso de formação de amilóides, investigamos a agregação do domínio GTPase da septina 6 (SEPT6G) e do complexo formado com o domínio GTPase da septina 2 (SEPT2G-SEPT6G). A temperaturas de até 15°C, tanto SEPT6G quanto SEPT2G-SEPT6G apresentam-se predominantemente diméricas em solução. Já a 25°C, o heterodímero SEPT2G-SEPT6G permanece estável enquanto agregados maiores de SEPT6G evoluem e coexistem em solução com SEPT6G-SEPT6G dimérica, sendo que a proporção de dímeros diminui com a temperatura. No estudo das MVs, mostramos que miméticos lipossomais de DPPC e DPPC:DPPS (9:1) possuem as mesmas características estruturais na ausência e presença de cálcio na solução. A interação da proteína anexina V humana (A5), envolvida em processos de biomineralização, impacta na membrana modelo induzindo a formação de nanoporos. A adição da fosfatase alcalina tecido não-específico (TNAP) não altera as propriedades estruturais do proteolipossomo na presença de A5. A ação do surfactante dodecil sulfato de sódio (SDS) a 30 mM não altera a conformação da albumina soro bovina (BSA), de maneira que é observada a formação de micelas de SDS coexistindo com a proteína livre em solução. Já a adição de 50 mM de SDS induz um desenovelamento parcial da proteína, identificado pela análise das curvas de SAXS via modelo de \"colar de pérolas\". A ação de uréia a 3 M e 8 M promove um desenovelamento parcial e total da BSA, respectivamente, com subsequente agregação de proteína dependente da temperatura (T > 30°C). A adição de 6 mM de SDS em proteínas parcialmente desenoveladas pela ação da uréia promove um desenovelamento mais acentuado. O potencial efetivo resultante da interação entre duas proteínas distintas, BSA e lisozima a concentração total de 100 mg/mL em solução, pH 7.0, foi obtido da análise de curvas de SAXS. Para isto, utilizou-se uma análise simplificada (em primeira aproximação) considerando um potencial efetivo de interação entre BSA-BSA, lisozima-lisozima e lisozima-BSA. Variamos a razão molar BSA:LISO até 1:42. No pH estudado, BSA tem uma carga residual superficial de -11e, enquanto a lisozima possui +9e. Conforme variamos a razão molar BSA:LISO, observamos dois regimes para o potencial efetivo resultante: i) até BSA:LISO 1:2, a carga efetiva do sistema é praticamente nula com um potencial resultante de caráter atrativo e ii) para razões entre BSA:LISO 1:3 a 1:42, a carga efetiva aumenta e o potencial resultante tem caráter repulsivo. Assim, lisozima e BSA coexistem sem agregar, através de um delicado balanço de forças atrativas e repulsivas no sistema.In this work we have used small-angle x-ray scattering (SAXS) to study four systems of biological interest. We aim to investigate the self aggregation of proteins and protein complexes that would form amyloid fibers; protein/protein interaction, simulating high concentrations; protein/cell-membrane interaction, simulating extracellular matrix vesicles (MVs) from biomineralizing systems; and protein/denaturating-agents interactions. On the case of amyloid formation, we have investigated the aggregation of G-domain of septin-6 (SEPT6G) and the protein complex formed with G-domain of septin-2 (SEPT2G-SEPT6G). At temperatures lower than 15°C, both SEPT6G and SEPT2G-SEPT6G were found predominantly as dimers. At 25°C, SEPT2G-SEPT6G heterodimer is still stable while aggregates of SEPT6G grow. Both coexist in solutions of SEPT2G-SEPT6G dimers, with the percentage of dimers decreasing the higher the temperature. As for the study of MVs, we have shown that DPPC and DPPC:DPPS (9:1) liposomal mimetics have the same structural characteristics at the absence or presence of Calcium. The interaction with human annexin V protein (A5), related to biomineralization processes, affects the model membrane by the creation of nanopores. The addition of tissue-nonspecific alkaline phosphatase (TNAP) does not change the structural properties of the proteoliposome when A5 is present. The addition of SDS surfactant (30 mM) does not alters the conformation of bovine serum albumin (BSA), and we have observed the formation of SDS micelles coexisting with free protein in solution. The addition of 50 mM of SDS, on the other hand, induces the partial unraveling of the protein, as seen by the analysis of SAXS data via the pearl necklace\'\' model. The effect of adding 3M and 8M urea is, respectively, the partial and total unraveling of BSA, with ensuing aggregation of the protein dependent on the temperature (T > 30°C). The introduction of SDS 6mM promotes further unraveling in proteins that were previously partially unraveled by urea. The resulting effective potential for the interaction between BSA and lysozyme at total concentration of 100mg/ml and 7.0 pH has been obtained from the analysis of SAXS curves. In order to obtain this result we have used a simplified analysis (first order approximation) in which were considered the effective potentials for the interactions between BSA-BSA, lysozyme-lysozyme and lysozyme-BSA. We have varied the BSA:LISO molar ratio up to 1:42. At the studied pH, BSA has a surface residual charge of -11e, and lysozyme has +9e. As we changed the BSA:LISO molar ratio, we have found two regimens for the resulting effective potential: i) up to BSA:LISO 1:2, the effective charge of the system is virtually zero and the resulting potential is attractive; and ii) for BSA:LISO between 1:3 and 1:42 the effective charge increases, and the resulting potential is repulsive. Therefore, both lysozyme and BSA coexist without forming aggregates, by a delicate balance of attractive and repulsive forces.
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Vander, Broek Charles William. "Subversion of host cellular processes by the melioidosis pathogen, Burkholderia pseudomallei." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/25402.
Abstract:
Burkholderia pseudomallei is an intracellular pathogen and the causative agent of melioidosis, a severe disease of humans and animals. One of the virulence factors critical for early stages of infection is the Burkholderia secretion apparatus (Bsa) Type 3 Secretion System (T3SS), a molecular syringe that injects bacterial proteins, called effectors, into eukaryotic cells where they subvert cellular functions to the benefit of the bacteria. Although the Bsa T3SS itself is known to be important for host cell invasion, intracellular replication, and virulence, only a few genuine effector proteins have been identified and the complete repertoire of proteins secreted by the system has not yet been fully characterized. The aims of this study are twofold. The first is to expand the repertoire of known effector proteins using modern proteomics techniques. The second is to explore the function of a subset of effector proteins to better understand their interaction with host cells. Isobaric Tags for Relative and Absolute Quantification (iTRAQ), a gel-free quantitative proteomics technique, was used to compare the secreted protein profiles of the Bsa T3SS hyper-secreting mutants of B. pseudomallei with the isogenic parent strain as well as a mutant incapable of effector protein secretion. This study provides one of the most comprehensive core secretomes of B. pseudomallei described to date and identified 26 putative Bsa-dependent secreted proteins that may be considered candidate effectors. Two of these proteins, BprD and BapA, were validated as novel effector proteins secreted by the Bsa T3SS of B. pseudomallei. To determine the possible function of two effector proteins, BipC and BapA, a yeast two-hybrid system was used to identify host cell proteins the effectors interact with. The proteins were screened against a library of human proteins for interactions. BapA interacted with 2 proteins while BipC interacted with 14. Both BapA and BipC were shown to interact with human C1QBP, a mitochondrial protein involved in inflammation, immunity and autophagy. Finally, the Bsa T3SS protein BipC was characterised in its ability to interact with actin. This study is the first evidence that BipC has the ability to bind to filamentous actin, but not monomeric actin. This binding is direct and no intermediate proteins are required for the interaction. Ectopic expression of BipC in eukaryotic cells caused cytoskeletal rearrangements consistent with an actin-binding protein. The core secretome represents a substantial resource of targets that will be mined for improved diagnostic assays and vaccines. Diagnostics that will detect early stages of disease to allow for more effective antimicrobial intervention are currently lacking. Furthermore, there is scope to design diagnostic assays with dual use such as to detect both melioidosis and infection of cystic fibrosis patients with the closely related opportunistic pathogen B. cepacia. The description of novel T3SS effector proteins is also of considerable value since T3SS proteins are often potent B- and T- cell antigens representing promising components of sub-unit vaccines. Such effector proteins commonly modulate cellular processes such as phagocytosis, inflammasome activation and cell cycle progression, hence the function of the predicted T3SS effectors will provide a series of future research opportunities.
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Ayre, Lorna M. "The adsorption of proteins onto ultrafiltration membranes." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/35236.
Abstract:
The mass of five proteins (Bovine serum albumin (BSA), casein, lysozyme, ovalbumin and pepsin) adsorbed to five different membrane materials (of various hydrophobicities) was quantified using a static system and analysed to establish any trends. Comparing the results from the five membranes it seems that there were no obvious trends between the protein masses adsorbed indicating that it may not be just one aspect of protein structure that is important in the adsorption process. Many investigations have indicated that the protein may undergo a conformational change during the adsorption process. Disulphide bridges contribute readily to the stability of the protein molecule and it was hypothesised that if such a structural change occurred, it would result in the breakage of these covalent bonds. To this end, the free thiol group content of the proteins was quantified before and after adsorption.
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Schveitzer, Bianca. "Interação de albumina do soro bovino (BSA) com sais biliares induzidas por surfactantes aniônicos." Florianópolis, SC, 2006. http://repositorio.ufsc.br/xmlui/handle/123456789/88505.
Abstract:
Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Química.Made available in DSpace on 2012-10-22T09:53:28Z (GMT). No. of bitstreams: 1 248372.pdf: 1217271 bytes, checksum: 7861054257955b37543892f0a15765e1 (MD5)
Neste trabalho, o sal biliar empregado foi o colato de sódio (NaC) para estudar o processo de ligação competitiva entre NaC e o dodecilsulfato de sódio (SDS) sobre a albumina do soro bovino (BSA), em uma solução tampão 0,02 M tris-HCl, em pH 7,5 e a 25 C. A associação entre o NaC e o SDS com a BSA foi monitorado em baixas concentrações de surfactantes onde somente o processo de ligação específica se desenvolve, e também foi acompanhado em altas concentrações de surfactante onde o processo de ligação cooperativa pode ser observado. Em baixas concentrações de surfactante, a metodologia aplicada para monitorar o processo de ligação específica está baseada na análise do efeito da concentração SDS e do NaC e ainda de misturas destes surfactactantes, sobre a intensidade de fluorescência dos resíduos de triptofano da BSA. A metodologia é empregada para se medir a quantidade de monômeros de surfactante distribuidos sobre a molécula de proteína onde a ligação ocorre, como pode ser observado pela supressão da fluorescência dos grupos cromóforos. A análise, baseada na quantidade de molécula de surfactante ligada sobre a proteína, indicou que o SDS é um supressor de fluorescência mais eficiente que o sal biliar. São necessárias 4-6 moléculas de NaC ligadas sobre a proteína para se obter a mesma eficiência na supressão que uma única molécula de SDS. Em altas concentrações de surfactante, os perfis das bandas de emissão de fluorescência são apresentados pela razão de A0/A em função da concentração de surfactante, onde A0 e A representam as áreas das bandas de emissão na ausência e em presença de surfactante, respectivamente. Uma outra metodologia, onde emprega-se gráficos de condutividade elétrica em função da concentração de surfactante, foi usada, para misturas de SDS e NaC, para investigar o processo de associação, e para determinação de parâmetros de ligação, como concentração de agregação crítica, cac, e concentração micelar crítica, cmc.
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Ferraz, Caroline Cristina. "Desenvolvimento de uma membrana nanoestruturada à base de poliacrilamida para veiculação de proteínas." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-19112013-145148/.
Abstract:
Hidrogéis são membranas formadas pela reticulação de cadeias poliméricas, empregados na área farmacêutica como produtos biomédicos. Dentre os principais polímeros selecionados para a síntese de hidrogéis, destaca-se a poliacrilamida (PAAM) devido às suas propriedades como hidrofilicidade e alto grau de intumescimento. Proteínas terapêuticas e enzimas são veiculadas em hidrogéis como carreadores de fármaco ou como dispositivos para tratamento de feridas e escaras na pele. Este trabalho teve como objetivo a síntese de uma membrana à base de PAAM favorável para veiculação de proteínas. As proteínas empregadas foram papaína e albumina de soro bovino (BSA) e as etapas do processo englobaram síntese da membrana, adição das proteínas no sistema, irradiação em condições específicas e caracterização da membrana. Ao utilizar temperaturas criogênicas na síntese e na irradiação das amostras, houve predomínio de reticulação da cadeia polimérica, fato que não ocorria em temperatura ambiente. As membranas foram obtidas com incorporação dos ativos na concentração de 0,2 a 1% (p/p), obtendo-se concentração de PAAM entre 4% a 10% (p/p), as quais receberam irradiação com raios gama provenientes de uma fonte 60Co, na dose de 25 kGy. Nas condições realizadas, as membranas não apresentaram citotoxicidade nem adesão celular, o perfil de liberação das proteínas foi adequado, a papaína manteve sua bioatividade preservada apesar do decaimento biológico e, segundo estudos de carga das moléculas, a membrana possui maior afinidade com a papaína, liberando-a mais lentamente. Desta forma, o método proposto e as membranas obtidas foram apropriados para a obtenção de um biomaterial.The use of hydrogels for biomedical purposes has been extensively investigated. Polyacrylamide (PAAM) is widely used due to properties such as hydrophilicity and swelling degree. Pharmaceutical proteins correspond to highly active substances which may be applied for distinct purposes. This work concerns the development of radio-synthesized hydrogel for protein release using papain and bovine serum albumin (BSA) as model proteins. The polymer was solubilized (1% w/v) in water and lyophilized. The proteins were incorporated into the lyophilized polymer and the hydrogels were produced by simultaneous crosslinking and sterilization using gamma radiation at 25 kGy under frozen conditions. The produced systems were characterized in terms of swelling degree, gel fraction, crosslinking density, fluid handling capacity, determination pH at point of polymer zero charge and evaluated according to protein release, bioactivity, cytotoxicity and cell adhesion. The hydrogels developed presented different properties as a function of polymer concentration and the optimized results were found for the samples containing 4-10% polyacrylamide. Protein release was controlled by the electrostatic affinity of acrylic moieties of polymer and proteins. This selection was based on the release of the proteins during the experiment period (up to 50 hours), maintenance of enzyme activity and the nanostructure developed. The system was suitable for protein loading and release and according to the cytotoxic assay and cell adhesion it was also adequate for biomedical purposes and this method was able to generate a matrix to protein release.
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Zheng, Yu 1970. "Melt growth of BSO (Bi₁₂SiO₂₀) : critical issues for growth in a micro-g environment." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9129.
Abstract:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1999.Includes bibliographical references (leaves 117-122).
Bismuth Silicate, Bi12Si020, is a body-centered cubic oxide exhibiting non-linear optical preperties which make it a target for many applications including optical information processing. This project is to investigate and resolve some critical issues associated with the Bridgman growth of BSO under the microgravity conditions, which can be divided into three phases according to the subject in each phase. (1) The wetting behavior between BSO and the confinement material, platinum, is critical in a Bridgman type of growth (Chap 3). The sessile drop method combined with a drop shape analysis was used to measure and compute the three-phase contact angles and the surface tensions ofBSO melts under varying partial pressure of oxygen (P02). The contact angle changed from 45° to less than 15° as P02 increased from 104 atm to 10-2 atm, however, the surface tension of BSO melts (- 200 mJ/m2) showed no dependence on P02. Based on the partial wetting conditions, platinum confinements for the growth of BSO with and with out gravity were designed. (2) Thermal characteristics in a Bridgman system, specifically the distribution and the stability of the axial and radial thermal profile within the charge, are critical for the establishment of desirable growth environment (Chap 4 ). In this phase of study, the thermal characterization of a modified vertical Bridgman system for growth of BSO were conducted by measuring the axial and radial temperature distribution in a semitransparent dummy charge made of fused silica which has comparable thern1a] and optical properties as BSO. A modified control method, in which two control thermocouples are placed in the gradient zone, was proved effective in stabilizing the axial thermal gradient. Thermal radiation was found to have a significant role in determining the temperature distribution inside the semitransparent charge. Use of a metallic confmement around the charge was able to reduce the influence of the external thermal radiation, and generated the typical transition of isothermal profile from convex to planar, then to concave along the axial direction in the charge. The effect of the remaining thermal radiation through the metallic shield caused the asymmetry of the axial thermal profile and resulted iri a high position ( close to the hot zone) of the planar isotherm. (3) Three ground-based growth experiments were conducted in this phase using the proposed ampoule design and growth conditions (Chap 5). Single crystals with desirable interface morphology were obtained, which confirmed the effectiveness of the thermal characterization. The position of the interface shifted during the growth due to the end effects of a short charge. The solution to this problem is to use a longer charge and/or to place the two control thermocouples closer to each other. Embrittlement of platinum happened when the ampoule was sealed during the growth. To avoid this problem, a dynamic airflow system should be constructed in the VB furnace, and the ampoule should be left open during the growth process. Interesting solid phase inclusions with unknown identities were found in one VBgrown crystal. The origin of such inclusions, as well as their correlation to the growth conditions, is remained as the subjects for the future work. The support of the National Aeronautics and Space Administration is gratefully acknowledged.
by Yu Zheng.
Ph.D.
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Santos, Sandra Maria Lopes dos. "Síntese e caracterização de sílicas mesoporosas para adsorção de biomoléculas modelo (BSA, Lisozima e Celulase)." reponame:Repositório Institucional da UFC, 2013. http://www.repositorio.ufc.br/handle/riufc/11738.
Abstract:
SANTOS, S. M. L. Síntese e caracterização de sílicas mesoporosas para adsorção de biomoléculas modelo (BSA, Lisozima e Celulase). 2013. 135 f. Tese (Doutorado em Engenharia Química) – Centro de Tecnologia, Universidade Federal do Ceará, Fortaleza, 2013.Submitted by Marlene Sousa (mmarlene@ufc.br) on 2015-04-30T16:23:11Z No. of bitstreams: 1 2013_tese_smlsantos.pdf: 11070721 bytes, checksum: 6fc6081d469e5467fbc862361d1fda85 (MD5)
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Part of the cost of production of biomolecules with high purity and yield depends on the separation and purification steps used. In these steps, it is usually necessary to use chromatography techniques and one of the factors that influence on its high performance is the development of stationary phases or suitable adsorbents. The present study investigates the adsorption of biomolecules three model (bovine serum albumin - BSA, lysozyme - LYS cellulase and - CEL) in mesoporous silica obtained from tri-block copolymers as agents drivers structure. We report different synthesis procedures aimed at modifying the surface chemistry and promoting textural changes, such as enlargement and/or pores, and the mesoscopic ordering. In the first part of this thesis were synthesized (i) SBA-15 by two different routes, sol-gel and hydrothermal and (ii) SBA-16 by hydrothermal. In the second part, SBA-15 samples with different pore sizes and channel length were s ynthesized using 1,3,5-trimethylbenzene (TMB), heptane and ammonium fluoride (NH4F). TMB was used to increase the pore diameter and heptane combined with NH4F to modify the size of the channels of SBA-15. In the third part of the work, the acidity of SBA-15 was modified by the addition of zirconium with three molar ratios Si/Zr distinct (5, 10 and 15). The adsorption of the three target biomolecules was studied by experiments in stirred tanks. The results indicate that for pure silicas, higher adsorption capacities are obtained when the pH is close to the isoelectric point of biomolecule. Very promising results for were found the adsorption of proteins on silicas with larger pore diameters (above 10 nm), up to hundreds of milligrams per gram of adsorbent. In the case of materials with zirconium, the best results were fou nd for the materials with the lowest amount of said heteroatom (Si/Zr = 15), which have similar texture to the original support. This suggests that there may be a moderate acidity which-enhances the adsorption of the studied biomolecules or excess zirconium atoms lead to steric hindrances causing a decrease in the adsorption capacity of the biomolecule
Parte do custo de produção de biomoléculas com elevada pureza e o rendimento deste processo depende das etapas de separação e purificação utilizadas. Nestas etapas, geralmente é necessário utilizar técnicas de cromatografia e um dos fatores que influenciam no seu elevado desempenho é o desenvolvimento de fases estacionárias ou adsorventes adequados. O presente trabalho investiga a adsorção de três biomoléculas-modelo (albumina de soro bovino - BSA, lisozima - LYS e celulase – CEL) em sílicas mesoporosas obtidas a partir de copolímeros tribloco como agentes direcionadores estruturais. Relatam-se diferentes procedimentos de síntese que visam modificar a química da superfície e promover alterações texturais como, por exemplo, o alargamento e/ou encurtamento dos poros, bem como a sua ordenação mesoscópica. Na primeira parte da tese, foram sintetizadas (i) SBA-15 por duas rotas distintas, sol-gel e hidrotérmica, e (ii) SBA-16 por via hidrotérmica. Na segunda parte, amostras de SBA-15 com diferentes tamanhos de poros e comprimento de canais foram sintetizados utilizando 1,3,5-trimetilbenzeno (TMB), heptano e fluoreto de amônio (NH4F). O TMB foi utilizado para aumentar o diâmetro dos poros e o heptano combinado com NH4F, para modificar o tamanho dos canais da SBA-15. Já na terceira parte do trabalho, a acidez da SBA-15 foi modificada pela adição de zircônio com três razões molares Si/Zr distintas (5, 10 e 15). A adsorção das três biomoléculas-alvo foi estudada por experimentos em tanques agitados. Os resultados indicam que, para sílicas puras, maiores capacidades de adsorção são obtidas quando o pH está próximo ao ponto isoelétrico da biomolécula. Resultados muito promissores foram encontrados para a adsorção de proteínas sobre as sílicas com maior diâmetro de poros (acima de 10 nm), chegando a centenas de miligramas por grama de adsorvente. No caso dos materiais com zircônio, os melhores resultados foram encontrados para os materiais com a menor quantidade do referido heteroátomo (Si/Zr = 15), que apresentam textura similar ao suporte original. Isto sugere que pode haver uma acidez moderada ótima para a adsorção das biomoléculas estudadas ou que o “excesso” de átomos de zircônio leva a impedimentos estéricos que causam uma redução na capacidade de adsorção da biomolécula
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Santos, Sandra Maria Lopes dos. "Synthesis and characterization of mesoporous silica for the adsorption of biomolecules model (BSA, lysozyme and cellulase)." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14021.
Abstract:
CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel SuperiorConselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
Parte do custo de produÃÃo de biomolÃculas com elevada pureza e o rendimento deste processo depende das etapas de separaÃÃo e purificaÃÃo utilizadas. Nestas etapas, geralmente à necessÃrio utilizar tÃcnicas de cromatografia e um dos fatores que influenciam no seu elevado desempenho à o desenvolvimento de fases estacionÃrias ou adsorventes adequados. O presente trabalho investiga a adsorÃÃo de trÃs biomolÃculas-modelo (albumina de soro bovino - BSA, lisozima - LYS e celulase â CEL) em sÃlicas mesoporosas obtidas a partir de copolÃmeros tribloco como agentes direcionadores estruturais. Relatam-se diferentes procedimentos de sÃntese que visam modificar a quÃmica da superfÃcie e promover alteraÃÃes texturais como, por exemplo, o alargamento e/ou encurtamento dos poros, bem como a sua ordenaÃÃo mesoscÃpica. Na primeira parte da tese, foram sintetizadas (i) SBA-15 por duas rotas distintas, sol-gel e hidrotÃrmica, e (ii) SBA-16 por via hidrotÃrmica. Na segunda parte, amostras de SBA-15 com diferentes tamanhos de poros e comprimento de canais foram sintetizados utilizando 1,3,5-trimetilbenzeno (TMB), heptano e fluoreto de amÃnio (NH4F). O TMB foi utilizado para aumentar o diÃmetro dos poros e o heptano combinado com NH4F, para modificar o tamanho dos canais da SBA-15. Jà na terceira parte do trabalho, a acidez da SBA-15 foi modificada pela adiÃÃo de zircÃnio com trÃs razÃes molares Si/Zr distintas (5, 10 e 15). A adsorÃÃo das trÃs biomolÃculas-alvo foi estudada por experimentos em tanques agitados. Os resultados indicam que, para sÃlicas puras, maiores capacidades de adsorÃÃo sÃo obtidas quando o pH està prÃximo ao ponto isoelÃtrico da biomolÃcula. Resultados muito promissores foram encontrados para a adsorÃÃo de proteÃnas sobre as sÃlicas com maior diÃmetro de poros (acima de 10 nm), chegando a centenas de miligramas por grama de adsorvente. No caso dos materiais com zircÃnio, os melhores resultados foram encontrados para os materiais com a menor quantidade do referido heteroÃtomo (Si/Zr = 15), que apresentam textura similar ao suporte original. Isto sugere que pode haver uma acidez moderada Ãtima para a adsorÃÃo das biomolÃculas estudadas ou que o âexcessoâ de Ãtomos de zircÃnio leva a impedimentos estÃricos que causam uma reduÃÃo na capacidade de adsorÃÃo da biomolÃcula.
Part of the cost of production of biomolecules with high purity and yield depends on the separation and purification steps used. In these steps, it is usually necessary to use chromatography techniques and one of the factors that influence on its high performance is the development of stationary phases or suitable adsorbents. The present study investigates the adsorption of biomolecules three model (bovine serum albumin - BSA, lysozyme - LYS cellulase and - CEL) in mesoporous silica obtained from tri-block copolymers as agents drivers structure. We report different synthesis procedures aimed at modifying the surface chemistry and promoting textural changes, such as enlargement and/or pores, and the mesoscopic ordering. In the first part of this thesis were synthesized (i) SBA-15 by two different routes, sol-gel and hydrothermal and (ii) SBA-16 by hydrothermal. In the second part, SBA-15 samples with different pore sizes and channel length were s ynthesized using 1,3,5-trimethylbenzene (TMB), heptane and ammonium fluoride (NH4F). TMB was used to increase the pore diameter and heptane combined with NH4F to modify the size of the channels of SBA-15. In the third part of the work, the acidity of SBA-15 was modified by the addition of zirconium with three molar ratios Si/Zr distinct (5, 10 and 15). The adsorption of the three target biomolecules was studied by experiments in stirred tanks. The results indicate that for pure silicas, higher adsorption capacities are obtained when the pH is close to the isoelectric point of biomolecule. Very promising results for were found the adsorption of proteins on silicas with larger pore diameters (above 10 nm), up to hundreds of milligrams per gram of adsorbent. In the case of materials with zirconium, the best results were fou nd for the materials with the lowest amount of said heteroatom (Si/Zr = 15), which have similar texture to the original support. This suggests that there may be a moderate acidity which-enhances the adsorption of the studied biomolecules or excess zirconium atoms lead to steric hindrances causing a decrease in the adsorption capacity of the biomolecule
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Boury, Frank. "Influence des propriétés de surface de microsphères de poly(alpha-hydroxyacides) sur l'adsorption de la BSA." Paris 11, 1995. http://www.theses.fr/1995PA114801.
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Antonio, Ocleia Gomes de Araujo. "Impactos da implantação do sistema de bônus em equipes de trabalho: um estudo de caso na UN-BSOL Petrobrás na Amazônia." Universidade Federal de Minas Gerais, 2004. http://hdl.handle.net/1843/BUBD-9BFK7P.
Abstract:
The models to reward employees have been widespread and adapted to the new the business world we live, considering the new ways to manage the man-power. The bonus systems have come as an additional alternative to reward and keep talent in the companies. It is a polemic theme that has been discussed in the employees administration area. At UN-BSOL, the bonus system was applied in the year of 2000 and caused some conflicts in the organization, because the management model requires the man-power to work in groups, sharing ideas, results, practicing cooperation, but the bonus system rewards individually while the employees expect group rewards. Considering this aspect, the present paper had the objective to describe and demonstrate the impacts of the bonus system implementation on the work groups, according to the UN-BSOL employees perception. It was made a case study using 31 interviews from total of 352 employees. It was verified that the bonus system has generated positive and negative impacts on the work group. As positive impacts, the employees pointed out that the bonus system made possible the interaction among the workers and stimulated the creativity and also can be used to reward the work of some employees. As negative impacts, the bonus system generated competition among the employees and dissatisfactions about the way it was used, among the items that caused the dissatisfaction one of the most important is the missing of fare parameters. It is recommended that while applying a model of employees reward, among other aspects, it must be considered the subjectivity of the process, the cultural aspects of the organization, and also the sensibility of the employees about the applied model. The results of the paper may be considered valuable, not only for the gain of academic knowledge about the theme, but also for presenting a contribution to the company about the reward process on the employees.Os modelos de recompensar os empregados vêm sendo ampliados e adaptados ao contexto em que vive hoje o mundo empresarial, tendo em vista as novas formas de gestão de pessoas. Os sistemas de bonificações têm surgido como mais uma alternativa para premiação e retenção de talentos nas organizações. É um tema polêmico e vem sendo bastante discutido na área de administração de pessoal. Na UN-BSOL, o bônus foi implantado no ano de 2000 e causou alguns conflitos na organização, pois o modelo de gestão necessita que seus empregados trabalhem em equipes, compartilhando idéias, resultados, exercitando a cooperação, mas o bônus premia individualmente, quando os empregados esperam um reconhecimento em equipes. Nesse sentido, o presente trabalho teve como principal objetivo descrever e demonstrar impactos da implantação do sistema de bônus nas equipes de trabalho na percepção dos empregados da UN-BSOL. Foi realizado um estudo de caso e, por meio de entrevistas a 31 empregados, em um universo de 352, verificou-se que a adoção do sistema de bônus gerou impactos positivos e negativos no trabalho em equipe. Como impactos positivos, os empregados responderam que o bônus favorece um maior envolvimento das pessoas com os trabalhos, estimula a criatividade e serve para reconhecer o serviço de alguns empregados. Como impactos negativos, o bônus gerou, principalmente, competição entre os empregados e descontentamento pela forma como foi utilizado, destacando-se, dentre outros itens, principalmente a falta de critérios justos. Recomenda-se que, ao se aplicar um modelo de reconhecimento de empregados, dentre outros aspectos, seja levada em consideração a subjetividade no processo, os aspectos culturais da organização, bem como a sensibilização dos empregados para o modelo a ser aplicado. Os resultados da pesquisa podem ser considerados valiosos, não somente por agregarem valor ao conhecimento acadêmico sobre o tema, mas também por se apresentarem como contribuições à empresa pesquisada, relativamente à condução dos processos de reconhecimento de empregados.
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Soares, de Vasconcelos Gabriel. "Segmentação de pupila utilizando redes neurais batch - SOM." Universidade Federal de Pernambuco, 2011. https://repositorio.ufpe.br/handle/123456789/2729.
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Previous issue date: 2011Os recentes avanços da tecnologia de informação e o crescimento dos requisitos de segurança têm impulsionado o aprimoramento dos métodos de identificação pessoal. Os métodos de identificação tradicionais baseados em posse (cartões, chaves, entre outros objetos) ou conhecimento (login e senha, por exemplo) apresentam alguns incovenientes, considerando que os objetos podem ser perdidos, roubados ou falsificados e que nomes de usuários e senhas podem ser esquecidos ou até adivinhados. O desenvolvimento dos métodos biométricos de identificação pessoal surgem como uma alternativa para superar estas limitações. Nestes métodos, a associação da identidade passa a ser baseada em características próprias e inerentes a cada pessoa. Estas características representam o que indivíduo é ou como ele realiza alguma ação, e não um objeto que o indivíduo possui ou algo que ele precise lembrar. Desta maneira, as características biométricas não podem ser esquecidas ou compartilhadas e dificilmente são copiadas ou modificadas. Dentre todos os métodos biométricos, os sistemas baseados no reconhecimento de íris vêm ganhando destaque em virtude de ser considerado como uma das modalidades biométricas mais precisas. Uma de suas etapas mais críticas é a etapa de segmentação, na qual, a região da íris é localizada e extraída a partir de uma imagem do olho previamente coletada, para que os modelos biométricos posteriormente gerados contenham apenas informações de íris. Uma representação errônea da região de íris corromperá o modelo biométrico, resultando em baixas taxas de reconhecimento. Essa etapa é, geralmente, subdividida em duas: segmentação de pupila e segmentação de íris, assumindo que a partir da segmentação da pupila, a segmentação da íris torna-se menos complexa, devido, em parte, à área de busca pela íris ser reduzida aos arredores da pupila. Usualmente, as técnicas de segmentação de pupila são baseadas na detecção de círculos, porém, é comum a pupila apresentar-se com um formato irregular em imagens do olho, principalmente, devido a problemas durante a etapa de aquisição da imagem. Nesta dissertação é proposta uma nova técnica baseada na utilização de uma rede neural batch-SOM (BSOM) modificada para o problema de segmentação de pupila que, diferente de outras técnicas, pode assumir qualquer formato, ajustando-se de maneira mais precisa às fronteiras da pupila. Nesta dissertação, também foram sugeridos um método, baseado no algoritmo K-means, para inicializar a rede neural e um método de ajuste do contorno obtido pela rede BSOM. Os resultados finais alcançados mostraram-se excelentes para as bases CasiaIris-V3 Interval, CasiaIris-V4 Syn e MMU1
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Allmann, Bernhard. "Lernen im Fernunterricht eine Untersuchung zur Akzeptanz von fernunterrichtsrelevanten Grössen am Beispiel der Fernlehrgänge der BSA-Akademie /." [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=974384747.
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Richter, Doreen [Verfasser]. "Occurrence and fate of sulfonamides (p-TSA, o-TSA, BSA) in an urban water cycle / Doreen Richter." Berlin : Freie Universität Berlin, 2008. http://d-nb.info/1023023725/34.
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Diop, Bernand-Mantel Dior. "Films polymères minces à base de méthacrylate de glycidyle pour l'élaboration d'interfaces immunoréceptrices : étude par résonance de plasmon de surface." Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00610387.
Abstract:
Dans ce travail, nous avons cherché à mettre en évidence l'influence de la méthode de préparation de films minces de polymère pour la biofonctionnalisation de surfaces planes. Dans un premier temps, un polymère réactif, le poly(méthacrylate de glycidyle) p(GMA) a été choisi et sa capacité de fixation vis-à-vis d'une biomolécule modèle l'albumine de sérum bovin a été étudiée. Deux stratégies principales de préparation du film polymère ont été utilisées : la technique du " grafting onto " et celle du grafting from " avec deux voies de synthèse : la polymérisation radicalaire classique (PRC) avec l'amorceur en solution et la polymérisation initiée à partir de la surface avec un amorceur photochimique. Il a été montré que la méthode du " grafting from " permettait l'obtention de films d'épaisseur plus élevées que la technique du " grafting onto " avec une meilleure capacité de fixation de biomolécules de BSA. Ces films de p(GMA) se sont révélés relativement hydrophobes, ce qui nous incités à analyser l'influence de la balance hydrophobe/hydrophile des interfaces sur leurs propriétés, dans un second temps. Par la préparation de films copolymères poly (GMA-co-acrylamide) et poly(GMA-co-méthacrylate de glycérol) et la modification des films de poly(GMA) par de l'éthanolamine, l'influence de l'hydrophilie du film sur la capacité de fixation en molécules de BSA et l'activité de reconnaissance moléculaire de celles-ci ont été évaluées. Il a été démontré que par un choix judicieux de la méthode d'hydrophilisation du film polymère, il est possible de réduire considérablement l'adsorption non-spécifique de biomolécules d'où l'obtention de films polymères bioinertes. De plus, les résultats préliminaires ont montré qu'il est possible d'améliorer sensiblement la capacité de reconnaissance moléculaire entre la BSA et son anticorps l'anti-BSA.
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ANJOS, Jorge Luiz Vieira dos. "Interações da albumina de soro bovino com surfactantes e efeitos de antioxidantes sobre a oxidação de lipoproteínas de baixa densidade induzida por íons de cobre." Universidade Federal de Goiás, 2012. http://repositorio.bc.ufg.br/tede/handle/tde/1236.
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Previous issue date: 2012-08-02Human plasma contains primarily large proteins, ranging in composition and concentration as the individual's physiological state. Among these proteins, albumin and low density lipoprotein (LDL) have been widely studied. The albumin (the most abundant protein in blood plasma) is responsible for important functions in the human body due to its excellent ability to bind and transport small molecules. In turn, the LDL (responsible for transporting cholesterol to the cells) in its oxidized form is directly associated with atherosclerosis, the main cause of cardiovascular disease. In the first part of this work, the interaction of bovine serum albumin (BSA) with the ionic surfactants sodium dodecylsulfate (SDS), cetyltrimethylammonium chloride (CTAC) and N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (HPS) was studied by electron paramagnetic resonance (EPR) spectroscopy of spin label covalently bound to the single free thiol group of the protein. In the second part was studied the oxidation of human LDL by copper ions and also the antioxidant potential of polyphenols resveratrol, (+)-catechin and quercetin, using the EPR of a spin label, derived from stearic acid (5-DSA), and the method malondialdehyde content (MDA). Part I: The dynamics of the BSA and the thermodynamic parameters for transferring the nitroxide side chain from the more motionally restricted to the less restricted component were monitored through EPR spectra simulation. Whereas SDS and CTAC showed similar increases in the dynamics of the protein backbone for all concentrations used, HPS presented a smaller effect at concentrations above 1.5mM. At 10mM of surfactants and 0.15 mM BSA, the standard Gibbs free energy change was consistent with protein backbone conformations more expanded and exposed to the solvent, but with a less pronounced effect for HPS. In the presence of the surfactants, the enthalpy change, related to the energy required to dissociate the nitroxide side chain from the protein, was greater, suggesting a lower water activity. The nitroxide side chain also detected a higher viscosity environment in the vicinity of the Mal-5 induced by the addition of the surfactants. The results suggest that the surfactant-BSA interaction, at higher surfactant concentration, is affected by the affinities of the surfactant to its own micelles and micelle-like aggregates. Complementary DLS (Dynamic Light Scattering) data suggests that the temperature induced changes monitored by the Mal-5 reflects local changes in the vicinity of Cys-34 BSA residue. Part II: The oxidative process induced by copper ions results in lipid peroxidation of LDL (evidenced by high concentration of MDA) could also be monitored by the decrease in the dynamics of 5-DSA, reflected in increased spectral parameter 2A//. The oxidation of LDL resulted in increased energy barrier that the spin labels must overcome to achieve higher degrees of motion. All polyphenols studied were able to protect LDL completely against oxidation for concentrations from 30 M, whereas the protection provided by the Butylated hydroxytoluene (BHT) occurred only partially. This result, based on data from the literature, was attributed to the ability of polyphenols act as scavenger and chelating agents, while the BHT acts just like scavenger due the presence of only a single hydroxyl group in its molecule.
O plasma humano contém principalmente grandes proteínas, com variação na composição e concentração conforme o estado fisiológico do individuo. Entre essas proteínas, a albumina e a lipoproteína de baixa densidade (LDL) têm sido amplamente estudadas. A albumina (proteína mais abundante do plasma sanguíneo) é a responsável por importantes funções no organismo humano devido a sua excelente capacidade de se ligar e transportar pequenas moléculas. Por sua vez, a LDL (responsável pelo transporte de colesterol para as células) em sua forma oxidada está diretamente associada à aterosclerose, principal causa de doenças cardiovasculares. Na primeira parte deste trabalho, a interação da albumina de soro bovino (BSA) com os surfactantes iônicos dodecil sulfato de sódio (SDS), cloreto de cetiltrimetilamônio (CTAC) e N-hexadecil-N,N, dimetil-3-3amônio-1-propano sulfonato (HPS) foi estudada através da espectroscopia de ressonância paramagnética eletrônica (RPE) do marcador de spin Mal-5 ligado covalentemente na cadeia lateral do resíduo Cys-34 da BSA. Na segunda parte foi estudada a oxidação da LDL humana por íons de cobre e também o potencial antioxidante dos polifenóis resveratrol, (+)-catequina e quercetina, usando a RPE de um marcador de spin derivado do ácido esteárico (5-DSA) e o método de formação de malondialdeído (MDA). Parte I: A dinâmica da BSA e os parâmetros termodinâmicos para transferir a cadeia lateral do nitróxido da componente de movimento mais restrito para a componente menos restrita foram monitorados através da simulação dos espectros de RPE. Enquanto o SDS e o CTAC mostraram efeitos similares na dinâmica da proteína para todas as concentrações usadas, o HPS apresentou menor efeito em concentrações acima de 1,5 mM. Em 10 mM de surfactantes e 0,15 mM de BSA, a variação da energia livre padrão de Gibbs foi consistente com a conformação da cadeia proteica mais expandida e mais exposta ao solvente, mas com um efeito menos pronunciado para o HPS. Na presença dos surfactantes, a variação de entalpia, relacionada a energia necessária para dissociar a cadeia lateral do nitróxido da proteína, foi grande, sugerindo uma menor atividade da água. A cadeia lateral do nitróxido também detectou um ambiente com maior viscosidade nas vizinhanças do Mal-5 induzida pela adição dos surfactantes. Os resultados sugerem que a interação surfactante-BSA, em altas concentrações, é afetada pela afinidade do surfactante por suas próprias micelas e agregados micelares incorporados na proteína. Complementarmente, dados obtidos com DLS (Dynamic Light Scattering) sugerem que as mudanças induzidas pela temperatura que são monitoradas pelo Mal-5 são mudanças locais na vizinhança do único resíduo Cys-34 da BSA. Parte II: O processo oxidativo induzido pelos íons de cobre resulta na peroxidação dos lipídios da LDL (evidenciado pela elevação da concentração de MDA) também pôde ser monitorado pela diminuição na dinâmica do marcador de spin 5-DSA refletida no aumento do parâmetro espectral 2A//. A oxidação da LDL acarretou no aumento da barreira da energia que os marcadores de spin precisam superar para alcançar graus superiores de movimento. Todos os polifenóis estudados foram capazes de proteger completamente a LDL contra a oxidação em concentrações a partir de 30 M, enquanto que a proteção fornecida pelo butil-hidroxi-tolueno (BHT) se deu apenas parcialmente. Este resultado, baseado em dados da literatura, foi atribuído à capacidade dos polifenóis atuarem tanto como scavenger quanto como quelantes, ao passo que o BHT é capaz de atuar apenas como scavenger devido à presença de apenas uma única hidroxila em sua molécula.
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Fernandes, Denise de Castro. "Efeitos do tempol sobre a interação entre peroxinitrito/CO2 com albumina e macrófagos: inibição da nitração de tirosinas e da oxidação de cisteínas e amplificação da nitrosação de cisteínas." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/46/46131/tde-17112014-160500/.
Abstract:
O tempol (TP) tem se mostrado um eficiente protetor em modelos inflamatórios. Os mecanismos de proteção contra espécies reativas de oxigênio foi bastante estudado mas sua interação com espécies reativas de nitrogênio ainda permanece pouco explorada. Recentemente, propusemos que o TP re-direciona a nitração de fenol mediada por peroxintrito (PN)/CO2 para nitrosação, pela sua reação com o radical CO3•‾. O produto desta reação, o cátion oxamônio, oxidaria PN para O2 e •NO. Este último produziria uma espécie nitrosante (N2O3) pela reação com o radical derivado do PN, •NO2 [Bonini e col. (2002) Chem. Res. Tox. 15: 506]. Para examinar se este mecanismo poderia operar in vivo, estudamos os efeitos do TP na reatividade do PN/CO2 frente a albumina (BSA) e macrófagos. Os efeitos do TP se apresentaram dependentes de sua concentração e da concentração de Cys. Apesar do TP não se mostrar catalítico, ele inibiu a oxidação de Cys (20-50%) e nitração de Tyr (70-90%) da BSA e aumentou a nitrosação de Cys (200-400%). No caso dos macrófagos tratados com PN/CO2, o tempol também inibiu a nitração (90%) e aumentou a nitrosação (300%). Assim, em condições fisiológicas, concentrações sub-estequiométricas de TP seriam capazes de redirecionar a reatividade dos radicais derivados PN, de oxidação de Cys proteica e nitração de Tyr para nitrosação de Cys. Desta forma, o TP poderia inibir a injúria em inflamações.Tempol has been shown to protect animals from oxidative stress conditions. Tempol\'s protective mechanisms against reactive oxygen species have been extensively studied but its interactions with reactive nitrogen species remain little explored. Recently, we proposed that tempol diverts peroxynitrite/CO2 mediated phenol nitration to nitrosation by reacting with CO3•‾ to produce tempol oxamonium cation that oxidizes peroxynitrite to O2 and •NO. The latter produces a nitrosating species by reacting with peroxynitrite-derived •NO2 [Bonini et al. (2002) Chem. Res. Toxicol. 15: 506]. To examine wether this mechanism operates in biological environments, we studied the effects of tempol on peroxynitrite/CO2 reactivity towards a protein, BSA, and cells, macrophages. Tempol\'s effects were dependent on its own and BSA-cys concentration. Although not a true catalyst, it inhibited BSA-cys oxydation (20-50%) and BSA-tyr nitration (70-90%) while increasing BSA-cys nitrosation (200-400%). In the case of macrophages treated with peroxynitrite/CO2, tempol also inhibited protein-tyr nitration (90%) and increased protein-cys nitrosation (300%). Then, under physiological conditions, a substoichiometric amount of tempol is able to divert peroxynitrite-derived radicais reactivity from protein-cys oxidation and protein-tyr nitration to protein-cys nitrosation. This may be the mechanism by wich tempol inhibits injury in inflammatory conditions.
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Rivera-Jiménez, Hernando Javier. "Desenvolvimento de marcadores moleculares espécie-específicos para a identificação de Eucalyptus." Botucatu, 2016. http://hdl.handle.net/11449/143468.
Abstract:
Orientador: Celso Luis MarinoResumo: The forest-breeding program in Brazil has the general objective of providing most adapted plants to different environments for various Brazilian regions, for fulfilling timber demands meant for multiple uses in the country. One of the main problems found in different forest breeding programs are the difficulty to identify the different species and hybrids. The use of molecular biology techniques in plant breeding programs is found very effective in the optimization of the time and the direction of these programs, particularly among those plants of the same subgenus. The process of selection and hybrid plants selected for planting in most cases; significantly increase the gain in terms of production and adaptability. The use of molecular markers to characterize the molecular variability of forest species has revolutionized genetic analysis in recent years. The bulk segregant analysis (BSA) is a technique used to identify molecular markers linked to monogenic, dominant or recessive characters. BSA technique in combination with Amplified Fragment Length Polymorphisms (AFLP) technique is an efficient methodology for the detection of polymorphism from genomic restriction fragments through PCR amplification; which helps in analyzing large number of loci for testing without the need for previous information of their sequence in respect to their dominance and reproducibility. The most recent and promising applications of molecular biological methods for the detection of small DNA fra... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor
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Dávila, Rodríguez María José. "Compostos carbonílicos heterobimetálicos de Ru(II)/Fe(II) : propriedades citotóxicas e estudo da interação com BSA e DNA." Universidade Federal de São Carlos, 2016. https://repositorio.ufscar.br/handle/ufscar/8032.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Ruthenium and iron-based drugs are an option for the development of improved chemotherapeutic agents for cancer treatment with lower toxicity. Thereby, this work present the in vitro cytotoxic activity and in vitro interaction studies of Calf-Thymus DNA (CT-DNA) and bovine serum albumin (BSA) with the synthetized carbonyl heterobimetallic compounds of Ru(II)/Fe(II) with general formula ct-[RuCl(CO)(N-N)(dppf)]PF6, with N-N = 1,10-phenantrholine (phen, 1); dipyrido[3,2-f:2′,3′-h]quinoxaline (dpq, 2); dipyrido[3,2-a:2',3'-c]phenazine (dppz, 3); dipyrido[3,2-f:2′,3′-h]quinoxalino[2,3-b]quinoxaline (dpqQX, 4) and dppf = 1,1’-bis(diphenylphosphino)ferrocene. Spectroscopy (IR, UV-vis and 1H-13C{1H}- and 31P{1H}-NMR) and voltammetry techniques along with elemental analysis were employed for the characterization of the complexes. Spectrofluorimetric titrations shows strong and spontaneous interactions of 1–3 with BSA through a static quenching mechanism resulting in binding constants in the order of 104 - 106 L·mol-1 at 310 K. Viscosity measurements and circular dichroism spectra prompts interactions of 1–4 with CT-DNA via non-classical intercalations or by an electrostatic pathway. MTT assays in cell lines MDA-MB-231 and V79-4 revealed IC50 values at range of 0,19 – 1,11 µmol·L-1 and 1,29 – 3,85 µmol·L-1 respectively, after 48 h of exposure to 1–4. However, stability studies of solutions 1 mmol·L-1 of 1–4 in DMSO shows their rapid reaction with this solvent.
Fármacos baseados em complexos heterobimetálicos de rutênio e ferro são alternativas para o desenvolvimento de melhores e menos tóxicos agentes quimioterápicos para o tratamento do câncer. Assim, este trabalho apresenta a atividade citotóxica in vitro e os estudos de interação in vitro com DNA de timo de bezerro (CT-DNA) e albumina de soro bovino (BSA) com os compostos carbonílicos heterobimetálicos de Ru(II)/Fe(II) de fórmula geral ct-[RuCl(CO)(N-N)(dppf)]PF6, com N-N = 1,10-fenantrolina (fen, 1); dipirido[3,2-f:2′,3′-h]quinoxalina (dpq, 2); dipirido[3,2-a:2',3'-c]fenazina (dppz, 3); dipirido[3,2-f:2′,3′-h] quinoxalino[2,3-b]quinoxalina (dpqQX, 4) e dppf = 1,1'-bis(difenilfosfino)ferroceno. Foram empregadas técnicas de espectroscopia (IV, UV-vis, e RMN de 1H, 13C{1H} e 31P{1 H}) e voltametria juntamente com a análise elementar para a caracterização dos compostos sintetizados. Titulações espectrofluorométricas mostraram interações fortes e espontâneas de 1–3 com a BSA através de um mecanismo de supressão da fluorescência estático, apresentando constantes de ligação na ordem de 104 – 106 L·mol-1 a 310 K. Medidas de viscosidade e espectros de dicroísmo circular, indicam interações de 1–4 com o CT-DNA via intercalações não clássicas ou por via eletrostática. Ensaios MTT nas linhagens celulares MDA-MB-231 e V79-4, revelaram valores de IC50 na faixa de 0,19 – 1,11 μmol·L -1 e 1,29 – 3,85 μmol·L-1 respectivamente, com 48h de exposição aos compostos 1–4. No entanto, estudos de estabilidade de soluções 1 mmol·L-1 de 1–4 em DMSO, mostraram sua rápida reação com este solvente.
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Landers, Alexis [Verfasser], Rita A. [Gutachter] Depprich, and Christoph [Gutachter] Suschek. "Freisetzungskinetik des Modellproteins FITC-BSA aus verschieden polymerbeschichteten bovinen Kollagenmatrices / Alexis Landers ; Gutachter: Rita A. Depprich, Christoph Suschek." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2019. http://d-nb.info/1175624837/34.
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Borba, Laise Costa. "Síntese de líquidos iônicos anfifílicos derivados de Oxa (tia) zolidinas e estudo da interação com BSA e lipossomas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/180654.
Abstract:
Os líquidos iônicos, por geralmente apresentar, em sua estrutura, uma cadeia alquílica apolar e uma parte polar, como o cátion imidazólio, podem ser considerados estruturas anfifílicas, e apresentam semelhanças com os tensoativos. Tais estruturas, devido a este caráter anfifílico, podem interagir com estruturas do tipo Lipossomas ou até mesmo com biomoléculas, como a BSA. Neste trabalho, foram sintetizados três líquidos iônicos inéditos, com rendimentos de 52 a 66%, acoplados a sistemas quirais derivados de aminoácidos naturais e de fácil obtenção, como a L-Cisteína, a L-Serina e a L-Treonina. Estes foram caracterizados tanto do ponto de vista estrutural, quanto por suas propriedades fotofísicas. Como procedimento metodológico utilizou-se de ciclocondensação de aminoácidos, esterificação de Steglich e alquilação para inserção de cadeia carbônica ao anel metil-imidazol. Para investigação e confirmação dessas estruturas utilizou-se de estudos de Ressonância Magnética de 1H e de 13C, Infravermelho, além das espectroscopias de absorção na região do UV-Vis e de emissão de fluorescência. Por fim, estes novos líquidos iônicos foram testados com lipossomas e BSA, cujos resultados mostraram boa interação com essas biomoléculas.Ionic liquids can be considered as amphiphilic structures and have similarities with the surfactants, once they generally have an apolar alkyl chain and a polar moiety, such as the imidazolium cation. Such structures, due to this amphiphilic character, may interact with liposome structures or even with biomolecules, such as BSA. In this work, three new ionic liquids containing chiral systems derived from naturally occurring amino acids, such as L-Cysteine, L-Serine and L-Threonine were synthesized, with yields ranging from 52 to 66%. They were fully characterized both from the structural point of view, and by its photophysical properties. As methodological procedures, amino acid cyclocondensation, Steglich esterification and alkylation were used. In order to investigate and confirm these structures, magnetic resonance studies of 1H and 13C, infrared, as well as absorption spectroscopies in the UV-Vis region and fluorescence emission were used. At last, these new ionic liquids were tested with liposomes and BSA, and the results showed good interaction with these biomolecules.
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Marchais, Hervé. "Preparation et caracterisation de microspheres de pla25ga50 chargees en bsa : etude de leur absorption intestinale chez le rat." Angers, 1994. http://www.theses.fr/1994ANGE0506.
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McKinley, Laura Ellen. "Neutron reflectivity studies of bacterial membranes, peptides and proteins." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/28874.
Abstract:
This thesis uses neutron and x-ray reflectivity to measure the interfacial structures of three molecular components associated with bacteria. Firstly, the way in which the membrane targeting sequence of a cell division protein interacts with monolayer models for the inner leaflet of the inner membrane of bacteria was measured at the air-water interface. Secondly, the influence of lipopolysaccharide on a monolayer model for the outer leaflet of the outer membrane of Gram-negative bacteria was measured at the air-water interface, as well as how this lipopolysaccharide interacts with an antimicrobial peptide. Finally, the structure of a layer of protein found at the surface of a Gram-positive biofilm was measured at the air-water interface. Binding of the membrane targeting sequence of the MinD protein (MinD-mts) to the inner leaflet of the cytoplasmic membrane is thought to be key for bacterial cell division. Modelling this membrane as a monolayer at the air-water interface, it was found that the insertion of the MinD-mts increased with decreasing lateral pressure within the monolayer, as well as with increasing unsaturation of the lipid components, and the incorporation of cardiolipin into the monolayer. Lipopolysaccharide (LPS) is the major component of Gram-negative outer membranes, such as Escherichia coli, and can be considered as having three structural components: lipid A, a core oligosaccharide, and a variable polysaccharide chain. By incorporating LPS into a model membrane at the air-water interface, it was found that the polysaccharide chain undergoes conformational changes depending on the area per molecule. The effect of the antimicrobial peptide Pexiganan on the structure of this LPS layer was also determined, and was found to insert into the polysaccharide chain layer, but have no impact on the conformation of the chains. In nature, many bacteria live within a biofilm structure. A critical component of the Gram-positive Bacillus subtilis biofilm is a surface active amphipathic protein called BslA, which gives rise to the formation of the highly hydrophobic surface of the biofilm. The kinetics of this film formation, its thickness, and the lateral packing of the protein at the air-water interface, were measured using both neutron and x-ray reflectivity. It was found that a native BslA protein consistently formed the same structural film, whilst the structure of films formed by mutant proteins depended on the conditions under which the film was formed.
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Blackard, Glynis D. "Examining Bachelor of Science in Nursing Accelerated (BSNA) Program Outcomes within a Traditional Faculty Workload Model versus a Clock Hour Faculty Workload Mod." Thesis, William Carey University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10192207.
Abstract:
Literature evaluating the impact of faculty workload on student outcomes of graduation and first-time pass for the National Council on Licensure Examination (NCLEX-RN®) is limited. Current models of workload are not specific and do not define the number of hours the faculty spends doing the work. In this day of decreased funding and increased requirement for quality in academia, it is important for nurse educators to understand how quality program outcomes, finances, and faculty workload are connected and impact student involvement.
The purpose of this study was to examine the relationship between the program outcomes of graduation and first-time pass on the National Council on Licensure Examination – Registered Nurse (NCLEX-RN®) for Bachelor of Science Nursing Accelerated (BSNA) student graduates in programs that used a traditional faculty workload model versus a clock hour faculty workload model.
The study, though limited, did begin to evaluate the impact of faculty workload on program outcomes. The intent and goals of the study were to research traditional workload models and alternative models proposed to address the cost of education and establish a baseline of how the models may impact program outcomes. In addition, the intent included evaluating how future changes may ultimately impact the student. Implications of the study included the consideration by faculty, school of nursing administration, and university administration of how faculty workload impacts the classroom and practice environment. Recommendations for further research conclude the study.
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Santos, Michelly Christine dos. "Nanopartículas magnéticas funcionalizadas com bicamada de ácido láurico: caracterização, associação de moléculas bioativas e estudo de interação com BSA." Universidade Federal de Goiás, 2012. http://repositorio.bc.ufg.br/tede/handle/tede/8867.
Abstract:
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Magnetic nanoparticles with two different chemical compositions, magnetite and zinc doped manganese ferrite were synthesized, functionalized with lauric acid bilayers and dispersed into water yielding stable aqueous colloidal suspensions at physiological pH. Bioactive molecules of different sizes, Amphotericin B and curcumin, were associated to the lauric acid bilayers of the suspended nanoparticles. X-ray diffraction analyses reveled a diffraction pattern characteristic of the cubic spinel crystalline phase for both samples. The nanoparticles average size estimated by Debye-Scherrer’s formula was 9 nm for zinc doped manganese ferrite and 8 nm for magnetite. The hysteresis curves showed that the nanoparticles are super paramagnetic at room temperature with saturation magnetization of 44.2 emug-1 for zinc doped manganese ferrite and 51.5 emug-1 for magnetite. The IR analysis showed the presence of lauric acid associated to the nanoparticles, and the TG curves showed a higher amount of lauric acid bonded to zinc doped manganese ferrite. The hydrodynamic diameters of the nanoparticles indicate that they are dispersed into the suspension as aggregates, and that the association of bioactive molecules did not affect the hydrodynamic sizes of the aggregates. The IR spectra confirmed the presence of bioactive molecules in the formulations and the UV-VIS spectra showed that these molecules are solubilized into the lauric acid bilayers in their monomeric forms. The functionalized nanoparticles containing the bioactive molecules present less negative zeta potential than the lauric acid functionalized nanoparticles, indicating that the bioactive molecules interact with the medium of the suspensions. The evaluation of aggregation of the nanoparticles in cell culture medium showed that the nanoparticles aggregation is significantly reduced by the addition of proteins (FBS and BSA) in cell culture medium. The study of interaction of the nanoparticles with bovine serum albumin before and after the association with the bioactive molecules showed that these systems present great affinity for BSA, with binding constants (Kb) in the range of 105 -106M-1. These results suggest that the nanoparticles functionalized with lauric acid bilayers, pure or associated to amphotericin B and curcumin, can be bioconjugated to proteins producing formulations with higher colloidal stability in biological media.
Nanopartículas magnéticas com duas diferentes composições químicas, magnetita e ferrita de manganês dopada com zinco, foram sintetizadas, funcionalizadas com bicamadas de ácido láurico e dispersas em meio aquoso produzindo suspensões coloidais estáveis em pH fisiológico. Posteriormente, foram associadas moléculas bioativas de tamanhos diferentes, Anfotericina B e curcumina, nas bicamadas de ácido láurico funcionalizadas nos dois tipos de nanopartículas em suspensão. A caracterização estrutural e composicional das nanopartículas foi realizada por difração de raios X e análise química dos teores de íons metálicos. Os difratogramas mostraram um padrão de difração referente à formação de material constituído por uma única fase cristalina cúbica do tipo espinélio. Os tamanhos médios estimados pela fórmula de Debye-Scherrer foram 9 e 8 nm para as nanopartículas de ferrita de manganês dopadas com zinco e de magnetita, respectivamente. Os teores dos íons metálicos indicaram um pequeno desvio na estequiometria final dos sólidos em relação à estequiometria inicial. As técnicas utilizadas para caracterizar as nanopartículas funcionalizadas antes e após a associação da Anfotericina B e da curcumina foram IV, UV-VIS, TG, VSM e ainda foram realizadas medidas de potencial zeta e de diâmetro hidrodinâmico. As curvas de histerese indicaram a formação de nanopartículas superparamagnéticas à temperatura ambiente com magnetização de saturação de 44,2 emug-1 para a ferrita de manganês dopada com zinco e 51,6 emug-1 para a magnetita. As análises de IV mostraram que as nanopartículas foram funcionalizadas com ácido láurico e as curvas de TG indicaram que as nanopartículas de ferrita de manganês dopadas com zinco contêm maior quantidade de ácido láurico do que as nanopartículas de magnetita. Os valores de diâmetros hidrodinâmicos das nanopartículas indicaram que as mesmas estão dispersas na suspensão na forma de agregados e que a associação das moléculas bioativas não influenciou nos tamanhos hidrodinâmicos dos agregados. Os espectros de IV comprovaram a presença das moléculas bioativas nas formulações e a análise dos espectros de UV-VIS mostrou que as moléculas bioativas estão solubilizadas nas bicamadas de ácido láurico em suas formas monoméricas. As nanopartículas funcionalizadas associadas às moléculas bioativas apresentaram potencial zeta menos negativo que as nanopartículas funcionalizadas, indicando que as moléculas bioativas interagem com o meio das suspensões. O estudo de agregação de nanopartículas em meio de cultura celular mostrou que a adição de proteínas contribui significativamente para a diminuição da agregação das nanopartículas neste meio. O estudo de interação entre a albumina de soro bovino (BSA) e as nanopartículas funcionalizadas antes e após a associação das moléculas bioativas mostrou que os sistemas têm grande afinidade com a BSA, com constantes de ligação (Kb) da ordem de 105–106 M-1. Esses resultados sugerem que as nanopartículas funcionalizadas com bicamadas de ácido láurico, puras ou associadas à Anfotericina B e à curcumina podem ser bioconjugadas a essa proteína produzindo formulações com maior estabilidade coloidal em meios biológicos.
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Neto, Diógenes de Sousa. "Interações da porfirina aniônica meso-tetrakis-4-fenilsulfonato (TPPS4) e da albumina de soro bovino (BSA) com surfactantes catiônicos." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-02042015-114519/.
Abstract:
A interação da porfirina aniônica meso-tetrakis (4-fenilsulfonato) (TPPS4) com modelos simples de membrana biológica foi investigada utilizando as técnicas de ressonância paramagnética eletrônica (RPE) e de espalhamento de raios-X a baixo ângulo (SAXS, do inglês small-angle X-ray scattering). Os modelos biomiméticos empregados no presente trabalho são constituídos de micelas catiônicas formadas a partir do surfactante catiônico cloreto de cetiltrimetilamônio (CTAC). Os experimentos de RPE e SAXS foram realizados a temperatura ambiente e nos pHs 4,0 e 9,0 a fim de verificar se o estado de protonação das porfirinas altera a natureza das interações com os sistemas micelares. As análises de RPE mostraram um comportamento similar para os marcadores de spin 5-DSA e 16-DSA; ou seja, a adição de porfirina às micelas catiônicas é seguida por uma redução da mobilidade de ambos os marcadores, principalmente para concentrações maiores de porfirina. Este comportamento foi atribuído ao efeito de empacotamento das micelas para o qual os resultados obtidos dos dados de SAXS parecem sustentar esta interpretação. Entretanto, a polaridade monitorada pelo marcador de spin 5-DSA mostrou ser praticamente a mês ma para todas as concentrações de porfirina e em ambos os valores de pH, sugerindo que o estado de protonação da TPPS4 não altera a natureza das interações envolvidas com a região das cabeças polares das micelas. Por outro lado, o marcador de spin 16-DSA mostrou uma pequena redução de polaridade para maiores concentrações de porfirina, principalmente em pH 4.0. Isso indica que a interação da porfirina também ocorre nas regiões hidrofóbicas das micelas. De fato, os ajustes dos dados de SAXS permitiram concluir que as distorções na forma de linha das curvas em função da concentração de porfirina estão associadas basicamente a uma redução do raio parafínico da micela de CTAC (parâmetro Rpar). Contudo, nenhuma mudança significativa na espessura da camada polar (parâmetro σpol) ou na sua densidade (parâmetro ρpol) foi observada. As curvas deSAXS de melhor ajuste foram obtidas assumindo as micelas de CTAC como elipsoides prolatos, onde a razão axial (parâmetro v ) não mostrou mudanças significativas para a faixa de 2-10 mM de TPPS4 e para os valores de pH estudados. A técnica de RPE também foi utilizada para monitorar a interação da albumina de soro bovino (BSA, do inglês bovine serum albumin) com o surfactante catiônico CTAC em pH 7,0. Marcadores de spin derivados do ácido esteárico (5-DSA e 16-DSA) ligados aos sítios de ligação de alta afinidade da BSA revelaram que na presença de surfactante os espectros de RPE são compostos de duas populações. Análises espectrais foram realizadas através do programa de simulação NLSL (do inglês, nonlinear leastsquares),o qual permitiu obter a difusão rotacional e a contribuição de cada componente nos espectros de RPE assim como avaliar a polaridade do ambiente onde os radicais nitróxidos estão estão dissolvidos. Os valores do tempo de correlação rotacional, τ,indicaram que a componente 1 apresenta um estado de mobilidade mais restrito devidoaos marcadores de spin estarem em contato com a proteína; a componente 2 menosimobilizada surge dos marcadores de spin localizados nas estruturas micelares. Para o 5-DSA, uma significante imobilização deste marcador permanece mesmo para altasconcentrações de surfactante, o qual é consistente com sua maior constante de ligaçãoquando comparado ao 16-DSA. O aumento da concentração de surfactante conduz a umaumento nos níveis de movimento da componente 1 seguido por uma redução da fraçãode marcadores de spin associado à esta componenteElectron paramagnetic resonance (EPR) and small angle X-ray scattering (SAXS) were used to investigate the interaction of the meso-tetrakis (4-sulfonatophenyl) porphyrin (TPPS4) with simple biological membrane models. In the present work, cationic cethyltrimethylammonium chloride (CTAC) micelles were used as mimetic models. RPE and SAXS experiments were performed at room temperature and at pHs 4.0 and 9.0 in order to evaluate whether the protonation state of the TPPS4 affects its interaction with the cationic micelle. EPR analysis showed a similar behavior for both spin labels 5-DSA and 16-DSA, i.e., the addition of porphyrin to the cationic micelles is followed by a reduction of mobility state for both spin labels, mainly at higher porphyrin concentrations. This behavior has been associated to the micellar packing effect, which seems to be supported by SAXS data. The polarity monitored by the spin label 5-DSA was practically the same in the whole porphyrin concentration range and pH values, suggesting that the protonation state of porphyrin did not contribute significantly for its interaction with cationic micelles. On the other hand, the spin label 16-DSA senses a slightly more hydrophobic environment as a function of porphyrin concentration, especially at pH 4.0. These findings indicate that the interaction of porphyrin also occurs at the hydrophobic core of cationic micelles. Indeed, the data obtained from the best fittings for SAXS curves allowed to conclude that the incorporation of porphyrin by the micelles is associated essentially to a shrinking of the paraffinic shortest semi-axis (R par parameter). Nevertheless, the polar shell thickness (σpol) and the electron density (Ρpol) parameters were practically unaltered in the whole porphyrin concentration range. The best-fit SAXS curves were achieved assuming for CTAC micelles a prolate ellipsoidal shape, where the axial ratio (v value) did not exhibit significant changes over the range 2-10 mM of TPPS4 and studied pH values. EPR technique was also used to monitor the interaction of bovine serum albumin (BSA) with cationic cethyltrimethylammonium chloride (CTAC) at pH 7.0. Spinlabeled derivatives of stearic acids (5-DSA and 16-DSA) bound to high-affinity binding sites of BSA revealed that in the presence of surfactant the EPR spectra are composed of two label populations. Spectral analysis was performed using the nonlinear leastsquares (NLSL) simulation program, which allows one to obtain the rotational diffusion rate and the contribution of each component in the EPR spectra as well as to evaluate ix environment polarity where the nitroxides are localized. The values of rotational correlation time, τ, indicated that component 1 displays a more restricted mobility behavior due to spin labels contacting the protein; the less immobilized component 2 arises from label localization in the bulk of micelles. For 5-DSA, a significant immobilization of probes remains even at higher surfactant concentrations, which is consistent with its higher binding constant as compared to 16-DSA. The increase of surfactant concentration leads to the increase in motional levels of component 1 followed by a reduction of this fraction of spin labels
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Annarelli, Céline Claire. "Etude de l'adsorption des protéines à la surface de biomatériaux : nouvelles méthodes de classification des interactions BSA-matériaux prothétiques." Lyon 1, 1998. http://www.theses.fr/1998LYO10016.
Abstract:
L'etude du comportement d'une solution aqueuse de proteines au contact d'un biomateriau solide est un sujet qui interesse les physiciens, les biologistes ainsi que les chirurgiens orthopedistes pour les materiaux destines a la realisation de protheses articulaires. La proteine retenue est une serumalbumine (bovine serum albumine - bsa) de type globulaire. La complexite de sa structure moleculaire lui confere une polyvalence physico-chimique autorisant une tres grande adaptabilite vis a vis de son environnement a courte ou moyenne portee. Nous avons choisi d'etudier l'interface solution-substrat et plus particulierement les regimes d'adhesion. Nous avons donc effectue des mesures de mouillabilite et de tension interfaciale qui furent historiquement parmi les premiers criteres de biocompatibilite et avons realise un petit laboratoire permettant de prendre en compte les phenomenes d'evaporation controlee qui generent un phenomene physique nouveau d'auto-organisation que nous avons appele effet diatomee ; celui-ci permet de caracteriser l'interaction proteine-substrat. La classification des materiaux a usage orthopedique qui en resulte corrobore celle obtenue par une methode des angles de contact qui renseigne sur l'evolution de la tension interfaciale solide-liquide. Des observations par microscopie a force atomique de cristallisation de sels supportes par des proteines adsorbees sur un substrat temoignent de la difference de structure du film de proteine selon le substrat. Ces mesures ont ete completees par des observations en interferometrie holographique, technique qui a egalement permis de visualiser les etats de surface de pieces prothetiques. En conclusion, nous avons mis en avant des methodes de laboratoire visant a selectionner des bons materiaux et nous avons essaye de caracteriser la couche de proteine afin d'anticiper sur le comportement en regime de lubrification dynamique et ainsi sur la longevite des materiaux prothetiques.
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Nyashanu, Mathew. "Beliefs and perceptions in the construction of HIV stigma and sexual health seeking behaviour among Black Sub-Sahara African (BSSA) communities in Birmingham, UK." Thesis, University of Wolverhampton, 2017. http://hdl.handle.net/2436/621154.
Abstract:
There is ample academic evidence indicating high levels of HIV stigma among BSSA communities. The research suggests that disadvantaged and marginalised social groups like the BSSA communities experience high levels of HIV and sexually transmitted infections. There is a significant amount of quantitative research in the public domain on HIV and stigma. Quantitative research has shown that BSSA communities present late with HIV and sexually transmitted infections often owing to HIV stigma. Currently there is limited published qualitative information on the factors influencing HIV stigma and sexual health seeking behaviour among BSSA communities, particularly from the perspective of the communities themselves. This research study explored beliefs and perceptions in the construction of HIV stigma and sexual health seeking behaviour among Black sub-Sahara African (BSSA) communities in one city in the UK. The Silences Framework, which sits within aspects of feminism, criticalist and ethnicity-based approaches, provided the theoretical underpinning for this study. An exploratory qualitative study methodology was used to identify and explore the key factors influencing the construction of HIV stigma and sexual health seeking behaviour among BSSA communities. Five focus groups and fifteen one-to-one semi-structured follow-up interviews were conducted to collect the data. The institution of Marriage, Religion, Reported HIV statistics, Politics and Immigration, HIV as a Sensitive subject, sexual health professionals Cultural competence, gender stereotyping, Sexual Orientation and Social Media emerged as key pillars underpinning the social scripts associated with the construction of HIV stigma and sexual health seeking behaviour. The experiences emanating from the pillars of HIV stigma, identified in this study, showed the impact of social, political and personal contexts associated with specific sexual scripts among the participants impacting on the construction of HIV stigma and sexual health seeking behaviour. The 'silences' contained in the socially determined scripts were important in understanding the phenomenon under investigation. The findings from this study were reviewed in light of current sexual health policies and strategies to consider how sexual health professionals and services can best meet the health care needs of BSSA communities. This thesis contributes to current knowledge of HIV stigma and ethnicity, by concluding that the construction of HIV stigma and sexual health seeking behaviour among BSSA communities takes place during different contexts of socialization, in a bid to conform to the perceived expectations of society which may be real or imagined. Furthermore, conformity is also influenced by commonly shared and personal appraisal of socially determined relevant issues. These contexts form the bases on which sexual scripts are given meaning and HIV stigma is constructed alongside a socially sanctioned pattern of sexual health seeking behaviour. This study makes an additional contribution in that it is the first time that The Silences Framework has been used to research HIV and stigma among BSSA communities. This research study compliments the currently available pool of quantitative data linking issues of HIV stigma and ethnicity in the United Kingdom. The findings from this exploratory qualitative research study reveal a wide range of critical issues to encourage further qualitative research in the area, while indicating new issues to consider in developing UK based interventions to address HIV stigma and sexual health seeking behaviour among BSSA communities.
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Lechelon, Mathias. "Long-range electrodynamic interactions among biomolecules." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0469/document.
Abstract:
L’étude des organismes vivants, la biologie, s’étend sur de nombreux domaines et notamment s’applique à comprendre le fonctionnement des êtres vivants. Les organismes les plus complexes comme les êtres Humains possèdent plusieurs niveaux d’organisation : ils sont constitués successivement d’organes, de tissus, de cellules, de biomolécules. On trouve plusieurs types de biomolécules dont les protéines, qui sont comme des minuscules outils qui permettent aux cellules de vivre et d’interagir avec leur environnement. Pour cela, les protéines doivent entrer en contact les unes avec les autres de manière très précise et déterminée. Cette thèse teste l’existence de forces électrodynamiques de longue portée qui leur permettraient d’interagir de manière rapide et guidée, via l’étude de l’absorption ou l’émission de ce type d’onde par des protéines, puis la diffusion de ces protéines en solution pour observer leur comportementThe study of living organisms, biology, extends over many fields and in particular, applies to understanding the functioning of living beings. The most complex organisms, such as human beings, have several levels of organization: they are made up successively of organs, tissues, cells, and biomolecules. There are several types of biomolecules including proteins, which are like tiny tools that allow cells to live and interact with their environment. To do this, proteins must come into contact with each other in a very precise and determined way. This thesis tests the existence of long-range electrodynamic forces which would allow them to interact in a rapid and guided way, by studying the absorption or emission of this type of wave by proteins, then the diffusion of these proteins in solution to observe their behavior
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Brandani, Giovanni Bruno. "Molecular dynamics simulations of protein adsorption at interfaces." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/20415.
Abstract:
Proteins can often adsorb irreversibly at fluid/fluid interfaces; the understanding of the adsorption mechanism has relevance across a variety of industrial (e.g. the creation of stable emulsions) and biological (e.g. biofilm formation) processes. I performed molecular dynamics simulations of two surfactant proteins as they interact with air/water and oil/water interfaces, describing the origin of the surface activity, the adsorption dynamics and the conformational changes that these proteins undergo at the interface. BslA is an amphiphilic protein that forms a highly hydrophobic coat around B. subtilis biofilms, shielding the bacterial community from an external aqueous solution. By investigating the behaviour of BslA variants at oil/water interfaces via coarse-grained molecular dynamics, I show that BslA represents a biological example of an ellipsoidal Janus nanoparticle, whose surface interactions are controlled by a local conformational change. All-atom molecular dynamics simulations then reveal the details of the conformational change of the protein upon adsorption, and the self-assembly into a two-dimensional interfacial crystal. Ranaspumin-2 is one of the main components of the tungara frog foam nest. Contrary to most surfactant proteins, its structure lacks any sign of amphiphilicity. All-atom simulations show that the adsorption proceeds via a two-step mechanism where firstly the protein binds to the interface through its flexible N-terminal tail and then it undergoes a large conformational change in which the hydrophobic core becomes exposed to the oil phase. I then developed a simple structure-based coarse-grained model that highlights the same adsorption mechanism observed in all-atom simulations, and I used it to compare the dynamics of adsorption and the underlying free energy landscape of several mutants. These results agree with and are used to rationalise the observations from Langmuir trough and pendant drop experiments. Colloids can often be considered simpler versions of proteins that lack conformational changes. I performed coarse-grained simulations of the compression of interfacial monolayers formed by rod-like particles. These simulations show a rich behaviour characterised by the flipping of adsorbed rods, nematic ordering and bilayer formation. I report the series of transitions that take place as the rod aspect ratio is increased from 3 to 15.
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Andersson, Tobias, and Mattias Martinson. "Licenshantering : - Är företag medvetna om sin licenshanteringssituation?" Thesis, University of Kalmar, School of Communication and Design, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:hik:diva-1940.
Abstract:
I ett samhälle där upphovsrätten och immaterialrätten blir allt mer uppmärksammad är det viktigt för företag att vara medvetna om sitt innehav av licenser för mjukvaror. I detta arbete kommer företags medvetenhet om deras licenshanteringssituation att undersökas. I den här rapporten kommer problemställningen att undersökas med hjälp av intervjuer med företag. Dessa intervjuer kommer att ske via telefon och per e-post. Ett liknande arbete har tidigare inte gjorts och därför känns det relevant samt intressant att göra denna undersökning.
Arbetet resulterade i intervjusvar från 11 företag. Det visade sig att företagens medvetenhet om deras licenshantering varierade stort, vilket även att storleken på företagen och innehav av en policy för licenshantering bland företagen gjorde. Metoden för licenshantering och licensinventering skiljde sig åt bland företagen.
Ett flertal program, tillammans med pärmar och Excel-listor var de dominerande licenshanteringsmetoderna bland företagen. Mjukvarutillverkarna och deras intresseorganisationer däribland BSA ställer krav på att företag som använder deras licensierade programvaror skall ha en strukturerad licenshantering. De ser gärna att företagen följer någon vedertagen metod för detta, en sådan metod är Software Asset Management, SAM.
Det är svårt att rekommendera någon licenshanteringsmetod och program som fungerar för samtliga företag, då användandet av dessa är väldigt företags- och organisationsspecifikt. De flesta större mjukvaror som finns i dagsläget följer en vedertagen metod för licenshantering och fungerar därmed bra att tillförlitligt inventera licenser med.
In a community where copyright and intellectual property law is getting more attention in the media, it is important for companies to be aware of their possession of software licenses. In this thesis we are going to investigate the awareness of the software licensing situation in some companies. To collect data that can be analyzed, we are interviewing companies. The interviews are performed by phone or e-mail. A similar report hasn’t been done before therefore it’s an interesting subject to look at.
The interviews resulted in answers from 11 companies. The answers showed that the awareness about software licensing among the companies had big variations. Some other things that varied among the companies were the size of the companies and the usage of software licensing policy within the companies. The way and method of handling software licensing also varied among the companies.
A lot of software programs, along with folders and Excel-lists dominated the method of handling software licenses among the companies. Software developing companies together with their interest organization for example BSA has demands on companies using their software to have a foreseeable documentation for the software licenses. They gladly see that the companies uses a best practice method to manage their license possessions, one best practice method is Software Asset Management, SAM.
It is hard to recommend a method for software license management to a non-specific company, because every company has a unique organization and computer network structure. Most of the big license management software is following a best practice method for software license management.
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Bonomo, Renata Cristina Ferreira. "Termodinâmica, modelagem e simulação do processo de adsorção e dessorção de BSA e β-lactoglobulina em cromatografia de interação hidrofóbica." Universidade Federal de Viçosa, 2005. http://www.locus.ufv.br/handle/123456789/9143.
Abstract:
Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2016-11-10T17:39:17Z
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texto completo.pdf: 1573232 bytes, checksum: 0e891caf5f28f0d44ad97897309027c3 (MD5)Made available in DSpace on 2016-11-10T17:39:17Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1573232 bytes, checksum: 0e891caf5f28f0d44ad97897309027c3 (MD5) Previous issue date: 2005-03-01
Neste trabalho foi estudado o processo de adsorção das proteínas albumina de soro bovino (BSA) e β-lactoglobulina (β-lg), provenientes do soro de queijo, em cromatografia de interação hidrofóbica variando-se as condições de temperatura e concentração de sal. Com os dados experimentais obtidos foi conduzida uma análise termodinâmica do processo. Foram realizadas, ainda, modificações no software SimuCromWin, desenvolvido por Saraiva (2003), que consistiram na inclusão da opção de utilização de outros modelos de isotermas além do modelo de Langmuir e o desenvolvimento de um programa que simula o processo de eluição em leito fixo. Avaliou-se, então, a influência dos modelos de isotermas na simulação do processo de adsorção assim como a otimização do processo de adsorção e dessorção das referidas proteínas em cromatografia de interação hidrofóbica. A partir dos resultados obtidos por meio do estudo da adsorção de BSA e β-lg em resina hidrofóbica (Streamline Phenil) foi possível observar que este processo é dependente da concentração de sal. Verificou-se, também, que o processo é espontâneo e entropicamente dirigido. Com as alterações no software SimuCRomWin, foram realizados estudos que indicaram o modelo de isoterma de Langmuir o melhor para simulações em cromatografia preparativa. Além disso, foi realizada a otimização do processo de separação das proteínas albumina de soro bovino (BSA) e β-lactoglobulina (β- lg), utilizando o software SimuCromWin e a técnica de superfície de resposta, na qual verificou-se que em temperaturas e concentrações de sal mais altas, dentro da faixa estudada, a resolução entre os picos é maior.
In this work was studied the adsorption process of whey proteins bovin serum albumin (BSA) and β-lactoglobulin (β-lg) at hydrophobic interaction chromatography (HIC) at four temperatures and salt concentrations. The thermodynamic analysis of the adsorptive process was made using the experimental data. Modifications were accomplished in the software SimuCromWin, developed by SARAIVA (2003), to promote the use of six types of isotherms and to include the elution stage of adsorption in fixed beds. Then, the influence of different isotherm models on the adsorption and dessorption process of BSA and β-lg and the optimization of these processes were studied. The results showed that the adsorption process of BSA and β-lg on Streamline Phenyl is dependent on salt and temperature for the two proteins. The adsorption process is driven by entropy and is favorable for both proteins. Studies were made after the modifications on the software SimuCromWin and indicated the Langmuir isotherm was the best isotherm model to simulated adsorption process for both proteins. The obtained experimental data, software SimuCromWin and surface response analysis permitted to determine the best conditions for adsorption and dessorption processes. The values found to adsorption process were 0.9 M and 313.15 K and to dessorption process were 0.85 M and 313.15 K, for both proteins.
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Boiangiu, Clara Dana. "Contribution physiologique des canaux mécanosensibles et des protéines de la famille BspA dans la protection contre le stress osmotique chez Bacillus subtilis et Erwinia chrysanthemi." Rennes 1, 2001. http://www.theses.fr/2001REN10087.
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Yasuda, Isao. "Pulmonary Stenosis with Intact Ventricular Septum: Assessment and Indication of Reconstructive Surgery for Residual Right-Ventricular Outflow Tract Obstruction." Thesis, Georg Thieme, 1991. http://hdl.handle.net/2237/16685.