Academic literature on the topic 'Liquid cristal'
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Journal articles on the topic "Liquid cristal"
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Suzuki, Kenji. "Friction Control Using Orientation of Liquid Cristal." Proceedings of the JSME annual meeting 2004.7 (2004): 323–24. http://dx.doi.org/10.1299/jsmemecjo.2004.7.0_323.
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Sirait, Marudut. "POTENSI DAMPAK LINGKUNGAN PADA PROSES PRODUKSI LIQUID CRISTAL DISPLAY (LCD) KOMPUTER." Journal of Engineering and Management Industial System 4, no. 1 (December 24, 2016): 40–48. http://dx.doi.org/10.21776/jemis.04.01.05.
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Sirait, Marudut. "POTENSI DAMPAK LINGKUNGAN PADA PROSES PRODUKSI LIQUID CRISTAL DISPLAY (LCD) KOMPUTER." Journal of Engineering and Management Industial System 4, no. 1 (December 24, 2016): 40–48. http://dx.doi.org/10.21776/ub.jemis.2016.004.01.5.
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Kondratyev, D. V., and N. G. Migranov. "Periodic Distortions of Smectic Liquid Cristal Layers in Magnetic and Electric Fields." Liquid Crystals and their Application 19, no. 1 (March 25, 2019): 79–86. http://dx.doi.org/10.18083/lcappl.2019.1.79.
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Honda, Shuichi, Takahiro Ishinabe, Shogo Takahashi, Yosei Shibata, and Hideo Fujikake. "Analysis on Bending Deformation of Plastic Substrates of Flexible Liquid Cristal Displays." Journal of The Institute of Image Information and Television Engineers 72, no. 10 (2018): J131—J135. http://dx.doi.org/10.3169/itej.72.j131.
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Berthele, P., H. Hamam, and J. L. De Bougrenet De La Tocnaye. "PROGRAMMABLE COMPUTER GENERATED HOLOGRAMS USING FERROELECTRIC LIQUID CRISTAL MATERIALS AS PHASE MODULATORS." Ferroelectrics 181, no. 1-4 (June 1996): 69–78. http://dx.doi.org/10.1080/00150193.1996.10399404.
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Azad, Gm S., Yizhe Huang, and Je-Chin Han. "Jet Impingement Heat Transfere on Pinned Surface Using a Transient Liquid Cristal Technique." International Journal of Rotating Machinery 8, no. 3 (2002): 161–73. http://dx.doi.org/10.1155/s1023621x02000155.
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Ferrantini, Cecilia, J. Manu Pioner, Daniele Martella, Raffaele Coppini, Nicoletta Piroddi, Paolo Paoli, Martino Calamai, et al. "Design of Biocompatible Liquid Cristal Elastomers Reproducing the Mechanical Properties of Human Cardiac Muscle." Biophysical Journal 116, no. 3 (February 2019): 264a. http://dx.doi.org/10.1016/j.bpj.2018.11.1433.
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Sudarmanto, Agus. "PEMBUATAN ALAT UJI KEKENTALAN MINYAK GORENG DENGAN MENGGUNAKAN METODE VISKOSITAS STOKES UNTUK PRAKTIKUM FISIKA DASAR 1 JURUSAN TADRIS FISIKA FAKULTAS ILMU TARBIYAH DAN KEGURUAN IAIN WALISONGO." Phenomenon : Jurnal Pendidikan MIPA 4, no. 2 (February 22, 2016): 51. http://dx.doi.org/10.21580/phen.2014.4.2.103.
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<p>Penelitian ini merancang dan merealisasikan pembuatan alat uji kekentalan minyak goreng dengan metode viskositas stokes dan indeks bias.<br />Pembuatan alat uji kekentalan minyak goreng dengan metode vis- kositas stokes terdiri dari sumber cahaya, sensor cahaya yang keluarannya diproses dengan mikrokontroler ATMega8535 dengan algoritma program kemudian hasilnya ditampilkan pada LCD (<em>Liquid Cristal Display</em>).<br />Hasil penelitian ini adalah bahwa pembuatan alat uji kekentalan min- yak goreng dengan metode viskositas stokes dan indeks bias pada prak- tikum Tadris Fisika Fakultas Tarbiyah IAIN Walisongo Semarang sudah dapat berfungsi sesuai dengan yang diinginkan dan data nilai viskositas- nya yaitu sebesar 4,80×10-3 Ns/m2.</p>
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Wirawan, Muhammad Teguh. "SISTEM OTOMATISASI POMPA AIR WATER COOLING TOWER MENGGUNAKAN MIKROKONTROLER ARM STM32F4 di PT.INDOSPRING Tbk." E-Link: Jurnal Teknik Elektro dan Informatika 15, no. 2 (November 18, 2020): 23. http://dx.doi.org/10.30587/e-link.v15i2.1989.
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Sistem Otomatisasi Pompa Air Water Cooling Tower Menggunakan Mikrokontroler Arm Stm32f4 Di Pt.Indospring Tbk. Sebagai pusat pengontrol alat dan pemroses data. Alat ini dapat mengontrol otomatisasi motor pompa sentrifugal menggunakan sensor arus acs 712, sedangkan untuk hasil sensornya sendiri ditampilkan pada LCD (Liquid Cristal Display). Sistem kerjanya adalah jika sensor arus men deteksi ampere berlebih pada pompa utama, maka secara otomatis pompa utama akan mati dan digantikan pompa cadangan yang telah disiapkan. Water cooling tower ini juga di lengkapi sensor suhu LM35 yang berfungsi untuk menghidupkan fan blower apabila suhu air lebih dari 40˚C. Untuk memudahkan petugas perawatan mengetahui level air kolam cooling tower maka ditambahkan sensor water level kontrol.
Berdasarkan pengujian dan pengamatan alat menggunakan tabel indikator keberhasilan telah menunjukkan bahwa Sistem Otomatisasi Pompa Air Water Cooling Tower Menggunakan Mikrokontroler Arm Stm32f4 Di Pt.Indospring Tbk berjalan dengan baik.
Dissertations / Theses on the topic "Liquid cristal"
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Fontanini, Sandro. "Propriedades Elásticas de um Cristal Líquido Liotrópico Nemático nas Vizinhanças da Interface Sólido-Cristal Líquido." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/43/43133/tde-03122013-164807/.
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Efetuamos o estudo da constante elástica efetiva de splay-bend K IND.13 por técnicas ópticas para um cristal líquido liotrópico. Neste experimento encontramos a razão entre K IND.13 e a constante elástica usual de Frank como sendo positiva e da ordem de 1. A análise teórica mostra que próximo à transição nemática-isotrópica o modelo termodinâmico para a temperatura de transição na superfície funciona razoavelmente bem. Na região de baixas temperaturas próxima à transição lamelarnemática são observados desvios importantes do comportamento teórico. No sentido interpretar os dados experimentais, propomos uma extensão fenomenológica simples do modelo termodinâmico que leva em conta as diferentes contribuições para a energia de superficie e a ordem lamelar residual próxima à superficie na fase nemática. Mostramos além disso que a constante clássica efetiva de splay-bend depende da concentração de ferrofluido na amostra. Analisamos também a influência do tratamento de superfície sobre a parte anisotrópica da tensão superficial de um cristal líquido liotrópico dopado com ferrofluido. Nosso resultado mostra que a superfície plana do vidro, independentemente da presença ou ausência de qualquer tratamento, estabiliza sobre si própria uma camada ou bicamada lamelar formada pelas moléculas anfifílicas do cristal líquido. Esta camada blinda o efeito dos filmes de Langmuir-Blodgett, ou o substrato puro sem nenhum tratamento, sobre o alinhamento de mesofases nemáticas liotrópicas.The effective splay-bend elastic constant K13 is studied by means of an optical technique for a lyotropic nematic liquid crystal. The ratio between K13 and the usual Frank elastic constant found in this experiment is positive and of the order of 1. The theoretical analysis shows that near the nematic-isotropic transition, the termodynamical model for the temperature surface transition works reasonably well. In the low temperature region near the lamellar-nematic transition, important deviations from the theoretical behavior are observed. In order to interpret our experimental data, we propose a simple phenomenological extension of the termodynamical model that takes into account the different contributions to the surface energy and of the residual lamellar order in the nematic phase. We show, furthermore, that the effective splay-bend elastic constant depends on the ferrofluid doping concentration. The influence of the surface treatment on the ansiotropic part of the surface tension of a discotic micellar lyotropic nematic crystal doped with ferrofluid analysed. Our results show that the flat glass surface, independently of the presence or of the absence of any treatment, stabilizes onto itself a lamellar layer - bilayer - formed by the amphiphilic molecules of the liquid crystal. This layer screens the effect of the Langmuir-Blodgett film - or of the pure substrate without any treatment - on the alignment of the lyotropic nematic mesofase.
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Nakamatsu, Sandra. "Dispersão de nanopartículas de látex em um cristal líquido liotrópico." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-27112008-125412/.
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Neste trabalho, estudamos a dinâmica de formação e dispersão de agregados de látex quando inseridos num cristal líquido liotrópico. Esse cristal líquido é um sistema ternário composto de laurato de potássio, cloreto de decilamônia e água; e apresenta fases nemáticas uniaxiais calamítica e discótica (NC e ND, respectivamente) e biaxial (NB). As partículas de látex possuem diâmetro de 100nm e partículas com diferentes tipos de recobrimentos foram testadas. Observamos que nas fases NC e NB há formação de aglomerados de partículas, porém na transição para a fase ND as partículas se dispersam no meio. Verificamos que esse processo de aglomeração e dissociação das partículas está relacionado com a transição de fase NB - ND e foi observado em dois sistemas hospedeiros por resfriamento e por aquecimento. No intervalo de temperatura que corresponde à fase nemática biaxial para o cristal líquido puro, observa-se que há um aumento na dimensão dos aglomerados, que se tornam anemométrico e orientados na direção de orientação do meio. Dois diagramas de fases foram construídos, variando-se a concentração de partículas dispersas no meio, e a composição relativa de surfactantes do sistema hospedeiro. Experimentos de espalhamento de raios X indicam que a distância média entre as micelas que formam o meio hospedeiro não é alterado pela inserção de partículas no cristal líquido e permanece a mesma em todas as fases nemáticas. Foram também realizados estudos de reologia que mostram que a viscosidade do sistema é alterada pela presença das partículas de látex. Os fenômenos observados são interpretados levando-se em conta as flutuações de orientação das micelas nas diferentes fases nemáticas.In this work, we studied the dynamics of agglomeration and dissociation of latex particles when inserted into a lyotropic liquid crystal. This liquid crystal is a ternary system formed by potassium laurate, decilamonium chloride and water, presenting uniaxial calamitic and discotic nematic phases (NC e ND, respectively) and a biaxial nematic phase NB. The latex particles have diameter of 100 nm and particles with different surface treatments were tested. It was observed that in the NC e NB phases the latex particles form agglomerates, however in the transition to the ND phase, the particles disperse in the medium. In the temperature domain of the biaxial nematic phase the agglomerates increase in size, become anisometric and oriented along parallel to the orientation of the medium. Two phase diagrams were built by varying the particle concentration dispersed in the liquid crystal and by varying the relative composition of surfactants of the liquid crystal. X rays diffusion experiments have shown that the average distance between the micelles in the host medium are not affected by the presence of the latex particles and remain the same in all nematic phases. Rheology studies were also performed and it was found that the viscosity of the system is affected by the presence of the particles. The observed phenomenon are interpreted taking into account the orientational fluctuations of miceles in the different nematic phases.
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Itri, Rosangela. "ESTUDO DE SISTEMAS MICELARES NOS ESTADOS ISOTROPICO E LIQUIDO - CRISTALINO." Universidade de São Paulo, 1991. http://www.teses.usp.br/teses/disponiveis/43/43133/tde-10092012-143341/.
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Foram estudadas fases micelares do sistema lauril (dodecil) sulfato de sodio (sls)/agua/decanol nos estados isotropico i e liquido-cristalino por espalhamento de raios-x com enfase nas transicoes de fase iSETAhexagonal hALFA e iSETAnematica nc. O estudo das posicoes do pico intermicelar no sistema binario sls/agua, indica que as micelas sao estaveis e levemente anisometricas nas fases i concentradas com empacotamento local de micelas esferoidais. Ocorre crescimento micelar na vizinhanca da transicao iSETAhALFA. A analise da curva de espalhamento i (q) em concentracoes menores (ate 9% em peso de sls) mostra ser possivel a determinacao da funcao distribuicao de distancias p (r), em casos especificos onde i (q) e dominada por um pico predominantemente relacionado a estrutura interna micelar. As anisometrias micelares NI sao deduzidas dos valores de dmax sendo p (r)=0 para r> OU =dmax obtemos NIAPROXIMADAMENTE IGUAL1.5. A analise das curvas de espalhamento de solucoes mais concentradas evidenciam que as micelas crescem mais por adicao de decanol ao longo da transicao de fase iSETAnc (NIAPROXIMADA MENTE IGUAL3) do que por aumento de concentracao de anfifilico no sistema binario ao longo de iSETAhALFA (NIAPROXIMADAMENTE IGUAL2,4). Estes resultados sao discutidos no ambito de previsoes teoricas recentes de transicoes de fase iSETAliquido-cristalinasMicellar phases of the system sodium dodecyl sulfate (SLS)/water/decanol have been studied by X-ray scattering in isotropic I and liquid crystalline states, with emphasis on the 1-+hexagonal Ha and 1nematic Nc phase transitions. Study of the intermicellar peak position in the binary SIS/water system, taking into account relative volumes of amphiphile, shows that micelles are stable and slightly anisometric in concentrated I phases, with local close packing of spheroidal micelles. Micellar growth occurs only near the 1Ha transition. Analysis of the scattering curve I( q) for lower concentrations (up to 9 wt% SLS) shows that it is possible to obtain the distance distribution function p(r), in specific cases in which l(q) is dominated by a peak due to the inner micellar structure. Micellar anisometries v are deduced from Dmax values, with p(r)=O for r Dmax. It results v.: 1.5. The electron density distribution p(r) obtained from p(r) in these lower concentrations confirm the existence of micellar anisometry.
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Bayon, Chloé. "Microlentilles et micro-miroirs en cristal liquide cholestérique." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30289/document.
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La structure moléculaire d'un cristal liquide cholestérique (CLC) est hélicoïdale et donne lieu à des propriétés optiques remarquables comme la réflexion sélective de la lumière. La structure cholestérique soulève des questions fondamentales comme la relation entre chiralités moléculaire et mésoscopique, et son impact sur les propriétés optiques. Elle est omniprésente en biologie (organisation de la chitine, de la cellulose, du collagène ou de la chromatine). Elle est aussi utilisée en technologie : en cosmétologie, dans les afficheurs nématiques super-torsadés, les écrans réflecteurs, les capteurs de température ou pression, les matériaux pour les applications photoniques en général. Le but du présent travail est de décrire et comprendre l'interaction de la lumière avec différents types de structures hélicoïdales non-monotones élaborées dans cette thèse - films cholestériques synthétiques (monocomposant ou hybrides i.e. dopés en nanoparticules d'or) - ou dans un matériau biologique (carapace du scarabée Chrysina gloriosa). Différentes techniques de caractérisation optique ont été utilisées suivant le matériau à étudier et les questions posées. La partie principale du manuscrit est dédiée aux microlentilles et micro-miroirs cholestériques. Nous avons étudié la texture polygonale cholestérique et mis en évidence qu'elle se comporte comme un réseau de microlentilles chirales à l'aide de la microscopie confocale couplée à la spectrophotométrie. Ces microlentilles organiques, élaborées en deux étapes par auto-assemblage, ont la particularité d'être sélectives en longueur d'onde. Nous avons ensuite montré que la texture polygonale de la carapace de Chrysina gloriosa, analogue biologique, est un réseau de micro-miroirs sphériques et de microlentilles convergentes. La seconde partie du manuscrit est consacrée à l'élaboration de matériaux hybrides CLC et nanoparticules d'or et à l'étude de leurs propriétés optiques. Les propriétés optiques de ces nanocomposites ont été sondées à l'aide de différentes techniques (résonance plasmon, spectrométrie Raman etc)The molecular structure of a cholesteric liquid crystal (CLC) is helical and gives rise to outstanding optical properties like the selective reflection of the light. Cholesteric structure raises fundamental questions such as the relationship between molecular chirality and mesoscopic chirality, and its impact on optical properties. It is omnipresent in biology (organisation of chitin, cellulose, collagen or chromatin). It is also used in technology: cosmetology, super-twisted nematic displays, reflective screens, temperature or pressure sensors, materials for photonic applications in general. The purpose of this work is to describe and understand the interaction of light with different types of non-monotonous helical structures elaborated in this thesis - synthetic cholesteric films (single-component or hybrid i.e. doped with gold nanoparticles) - or in a biological material (Chrysina gloriosa beetle). Several optical characterisation techniques have been used, depending on the sample to study and the questions which are rised. The main part of the manuscript is dedicated to cholesteric microlenses and micro-mirrors. We studied the cholesteric polygonal texture and highlighted that it acts as a chiral microlens array by using confocal microscopy coupled to spectrophotometry. These organic microlenses, developed in a two-step process by self-assembly, have the specificity of being wavelength-selective. We then showed that the polygonal texture of Chrysina gloriosa, as a biological analogous, is an array of spherical micro-mirrors and convergent microlenses. The second part of the manuscript is devoted to the elaboration of hybrid materials composed of CLC and gold nanoparticules and the study of their optical properties. Optical properties of these nanocomposites were probed using various techniques (plasmon resonance, Raman spectroscopy etc)
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Maximo, Guilherme José 1982. "Lipid thermodynamics = new perspectives on phase studies for applications in engineering = Termodinâmica de lipídios: novas perspectivas em estudos de fases para aplicações em engenharia." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/255144.
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Orientadores: Antonio José de Almeida Meirelles, Mariana Conceição CostaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-24T10:06:55Z (GMT). No. of bitstreams: 1 Maximo_GuilhermeJose_D.pdf: 6364914 bytes, checksum: 716122d30b63141c35ee3d3c3305de17 (MD5) Previous issue date: 2014
Resumo: Para o desenvolvimento de chocolates, manteigas, molhos para salada, cremes cosméticos, medicamentos ou biocombustíveis, assim como na otimização de processos de extração, refino, fracionamento, cristalização e produção de energia, os fenômenos de transição de fases dos sistemas lipídicos são temas, há muito tempo, de diversos trabalhos na literatura. O objetivo desses trabalhos tem sido avaliar como a composição dos produtos altera as suas propriedades físico-químicas e em especial aquelas relacionadas aos processos de fusão. De fato, alterações na temperatura exercem um grande impacto na estrutura cristalina da fase sólida dos sistemas graxos e, consequentemente, nas propriedades sensoriais e reológicas dos produtos. Essas alterações produzem comportamentos termodinâmicos tão variados que a determinação do equilíbrio de fases sólido-líquido desses sistemas representa um grande desafio. Não obstante, quanto maior a complexidade do sistema, menor é a compreensão do seu comportamento. Ou seja, apesar do grande número de trabalhos presentes na literatura envolvidos na investigação dos fenômenos de fusão de sistemas lipídicos, novos dados experimentais e abordagens teóricas para a modelagem dos diagramas são necessários para sua compreensão. Neste contexto, este trabalho teve dois objetivos principais. O primeiro relacionado à determinação e análise de diagramas de fases sólido-líquido de sistemas lipídicos binários de interesse para a indústria. O segundo foi desenvolver alternativas teóricas para aprimorar a representação dos diagramas de fases baseado em abordagens termodinâmicas clássicas. Portanto, onze sistemas binários compostos por triacilgliceróis, ácidos graxos e álcoois graxos foram avaliados. Esses sistemas são potenciais agentes de estruturação, formação de organogéis, produção e armazenamento de energia na indústria de alimentos, farmacêutica e de materiais. Os diagramas de equilíbrio sólido-líquido dessas misturas apresentaram comportamentos distintos, dependentes da formação de fases sólidas miscíveis ou imiscíveis e da não-idealidade do sistema. Além disso, foram estudados quatro sistemas formados a partir da reação ácido-base de Brønsted entre ácidos graxos e etanolaminas. Neste caso, a formação de líquidos iônicos próticos cristalinos com grande habilidade para auto-organização e comportamento não-Newtoniano singular podem atuar como auxiliares em diversas aplicações químicas e farmacêuticas. O problema imposto pela miscibilidade da fase sólida na construção dos diagramas de fases foi superado pela implementação de um algoritmo para a resolução de um sistema de equações não-lineares baseado nas equações fundamentais do equilíbrio sólido-líquido. O objetivo do algoritmo "Crystal-T" foi determinar a temperatura em que o primeiro e o último cristal se fundem durante o aquecimento do sistema. Para isso, a não-idealidade de ambas as fases líquida e sólida foi avaliada utilizando equações baseadas na energia de Gibbs em excesso, incluindo o método de contribuição de grupos UNIFAC, para o cálculo dos coeficientes de atividade. Considerando o aumento da produção mundial e do consumo de óleos e gorduras, este trabalho, a partir de demandas emergentes da indústria e da pesquisa científica, contribuiu na superação de alguns obstáculos relacionados à compreensão do equilíbrio de fases sólido-líquido de sistemas lipídicos para a engenharia de produtos e processos
Abstract: The phase transition phenomena of lipidic systems have long since been evaluated by several works in literature for developing chocolate, butters, dressings, spreads, cosmetic creams, medicines or biofuels as well as for optimizing processes such as extraction, refining, fractionation, crystallization or energy production. The aim of such works has been to answer how the products¿ composition can affect their physicochemical characteristics especially that related to the melting processes. In fact, changes in temperature highly impact the crystalline structure of fatty systems¿ solid phase and, consequently, in the sensorial and rheological properties of the products. These changes led to so many thermodynamic behaviors that the determination of the solid-liquid equilibrium of these systems can configure a particular challenge. However, the greater the complexity of the system the lower the understanding of its behavior. In other words, despite the number of works in literature involved in the investigation of the melting phenomena of lipidic systems, there is still a lack of experimental data and modeling approaches for their understanding. In this context, this work was conducted with two main goals. The first was focused on the measurement and comprehension of the solid-liquid equilibrium phase diagrams of lipidic binary systems of industrial interest. The second was aimed at the development of theoretical alternatives to improve the phase diagram description based on classical thermodynamic approaches. Thus, eleven binary systems composed by triacylglycerols, fatty alcohols and fatty acids were evaluated. Such mixtures are potential structuring, organogelating and energy storing agents for food, pharmaceutical and materials industry. The solid-liquid phase diagrams of these mixtures presented distinct behaviors depending on the formation of immiscible or miscible solid phases and the non-ideality of the system. Also, four systems built through a Brønsted acid-base reaction between fatty acids and ethanolamines were also evaluated. In this case, the formation of protic ionic liquid crystals with high self-assembling ability and marked non-Newtonian behavior are promising for pharmaceutical and chemical applications. The problem imposed by the partial miscibility of the solid phase in the construction of the phase diagrams was overtaken by the implementation of an algorithm based on the resolution of a non-linear equations system built by the solid-liquid equilibrium fundamental equations. The "Crystal-T" algorithm was aimed at the determination of the temperature at which the first and last crystal melts during the heating process. For this, the non-ideality of both liquid and solid phases was evaluated using excess Gibbs energy equations, including the group-contribution UNIFAC model, for the calculation of the activity coefficients. Taking into account the growing increase of the world production and consumption of fat and oils, this work, from industrial and academic emerging demands, contributed to overtake some barriers on the understanding of the solid-liquid phase equilibrium of lipidic mixtures for products and process engineering
Doutorado
Engenharia de Alimentos
Doutor em Engenharia de Alimentos
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Jacobs, Matheus Rychescki. "Parametrização de campo de força derivado de cálculos mecânico-quânticos para o cristal líquido 4-Ciano-4’-Pentilbifenila." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/171692.
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Simulações de Dinâmica Molecular tornaram-se uma ferramenta indispensável no estudo de sistemas em fase condensada, incluindo sistemas líquido-Cristalinos, e na predição de propriedades dinâmicas. Cristais líquidos possuem um leque enorme de aplicações, mas o estudo teórico destes sistemas torna-se complicado devido ao seu tamanho, ao método utilizado para obtenção dos parâmetros do campo de força e, principalmente, à transferibilidade dos parâmetros para outro estado termodinâmico. Tendo isso em vista, este trabalho propõe uma metodologia para parametrizar campos de força derivados de cálculos mecânico-quânticos que possuam um grau de transferibilidade confiável. O sistema escolhido neste trabalho foi o 4’-Pentil- 4-Carbonitrila, também conhecido como 5CB, pois o mesmo já é utilizado em diversos aparelhos óptico-eletrônicos; a parametrização intramolecular foi feita com o programa JOYCE, e a intermolecular, com o programa PICKY. Os parâmetros intramoleculares obtidos mostraram uma boa descrição da geometria interna do sistema, contribuindo para a parametrização intermolecular, a qual obteve uma excelente descrição de propriedades termodinâmicas. Este trabalho corrobora para a hipótese de que campos de força derivados de cálculos mecânico- quânticos podem descrever diferentes fases termodinâmicas com um alto grau de confiabilidade.Simulations using Molecular dynamics have become a powerful tool in the study of systems in condensed phase, including liquid-crystalline systems, and in the prediction of dynamical properties. Liquid Crystals have many applications, but the theoretical study of these systems is more complex because of their size, the method that was used in the force field parametrization and, mainly, because in most of the cases parameters cannot be transferred to another thermodynamical state. With that in mind, this work propose a methodology to parametrize force fields derived from quantummechanical calculations and which can be transferred to other thermodynamical state without losing important information. The chosen system in this work was the 4-Cyano-4’-Pentylbiphenyl, also known as 5CB, which have been used in many optical-electronic device and the intramolecular parametrization was done with the JOYCE program and the program PICKY was used in the intermolecular parametrization. The intramolecular parameters obtained show a good description of the internal geometry, contributes to the intermolecular parametrization, with we obtained an accurate description of the thermodynamical and physical chemical properties. This work corroborate to the hypothesis that force field derived from quantum-mechanical calculations can describe different thermodynamical states without losing important information.
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Segovia, Mera Alejandro. "Effets de la dispersion de nanoparticules dans un cristal liquide ferroélectrique sur les propriétés ferroélectriques et de relaxations diélectriques." Thesis, Littoral, 2017. http://www.theses.fr/2017DUNK0461/document.
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Ces travaux de thèse ont porté sur des matériaux constitués de dispersions de particules colloïdales nanométriques, issues d'un matériau ferroélectrique, dans un cristal liquide chiral à phase smectique ferroélectrique. Ils ont pour but d'étudier les effets occasionnés par ces dispersions sur les propriétés du nanocolloïde, notamment celles liées à leur ferroélectricité. Cette étude a montré que les comportements mésomorphes et ferroélectriques de ces matériaux sont conservés. Une baisse de polarisation spontanée ainsi qu'un recul des températures des transitions ont été mis en évidence pour des faibles concentrations en NPs. Une "transition" de ces comportements a été observée pour une concentration critique au-delà de laquelle les particules s'agrègent pour former des amas au sein du milieu cristal liquide. Nous nous sommes intéressés ensuite à deux modes de relaxation diélectriques. Le premier lié aux mouvements de distorsions de l'hélice dans la phase ferroélectrique, le second aux mouvements de compression des couches smectiques de part et d'autre de la transition ferroélectrique-paraélectrique. Les comportements observés semblent être gouvernés par les modifications des propriétés visco-élastiques des nanocolloïdes, occasionnés par l'intercalation des nanoparticules entre les couches smectiquesThe present thesis work concerns materials made of dispersions of nanometric colloidal particles, from a bulk ferroelectric material, dispersed within a chiral smectic phase of a ferroelectric liquid crystal. The goal of this work is to study the effect of the dispersed nanoparticles over the nanocolloïd properties, specially the ones related to ferroelectricity. This study showed no change over mesomorphic and ferroelectric behavior of the materials. A decrease in spontaneous polarization and phase transition temperatures was found for low nanoparticle concentrations. A "transition" of these behaviors was observed for a critical concentration, beyond which, nanoparticles aggregate and form clusters inside the liquid crystal matrix. Afterwards, we have studied two dielectric relaxation modes. The first one related to distorsions of the helix in the ferroelectric phase and the second one to the compression movements of the smectic layers around the ferroelectric-paralectric transition. The observed behaviors seem to be due to modifications of the visco-elastic properties of nanocolloids, produced by intercalation of nanoparticles between the smectic layers
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Tavares, Viviane. "Caracterização e processamento de telas de cristal líquido visando a reciclagem." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-22032007-150914/.
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As telas de cristal líquido (LCD) são usadas em TVs, calculadoras, telefones celulares, computadores (laptop e palm), vídeo games e agendas eletrônicas. O aumento e a rápida obsolescência tecnológica desses dispositivos eletrônicos causa o descarte excessivo de LCDs usados, diminuindo a vida útil de aterros. Por isso é necessário o desenvolvimento de uma metodologia de reciclagem de LCDs, que deve ser iniciada pela caracterização de LCDs, seguida do processamento das telas com objetivo de separar os materiais, utilizando algumas técnicas de Tratamento de Minérios. Os ensaios realizados para caracterização dos componentes da tela foram: solubilização em solvente; chama; infravermelho; DSC; MEV com EDS; difração de raios-X; e perda ao fogo. A seqüência identificada dos materiais de fora para dentro foi: triacetato de celulose, poli (álcool) vinil dopado com iodo, triacetato de celulose, cristal líquido, vidro com ITO, triacetato de celulose, poli (álcool) vinil dopado com iodo, triacetato de celulose, polímero não identificado com mica. Após a caracterização foi realizada a etapa de liberação de materiais, utilizando-se de moinhos de rolos, de disco, de martelos, de bolas, separação por álcool, imersão em nitrogênio líquido, e solubilização em água, para separação dos materiais recicláveis. A operação de Tratamento de Minérios que apresentou cerca de 98% de separação dos materiais foi com o moinho de martelos. Este material pode ser usado eventualmente como substituto da areia. Para viabilizar a separação dos materiais existe a necessidade de alteração no projeto das LCDs.Liquid crystal displays (LCD) are used in TVs, calculators, mobiles, computers (laptop and palm), video games and electronic agendas. The increasing and fast technological obsolescence of these electronic devices causes their extreme discard, decreasing the landfills useful life. Therefore it is necessary the development of a LCD recycling methodology which must be started by the LCDs characterization, followed by the displays processing with the objective of separating materials, using some Ore Treatment techniques. The characterization tests of the LDC components: solvent solubilization, flame, infrarred, DSC, MEV with coupled EDS, X-ray diffraction and loss on fire. The sequence of the identified materials were: celulose triacetate, poly vinyl alcohol with iodine, cellulose triacetate, liquid cristal, ITO glass, cellulose triacetate, poly vinyl alcohol with iodine, cellulose triacetate, polymer with muscovite. Following the characterization, the materials releasing step was performed. Firstly the LCDs were grinded using different kinds of mills, then the grinded materials were passed through several separation tests: separation on alcohol, immersion in liquid nitrogen and solubilization in water. Hammer milling present the best results. The project of the LCDs should be improved in order to allow the materials separation.
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Fernandes, Paulo Ricardo Garcia. "Birrefringência Induzida por Gradientes de Velocidades na Fase Isotrópica de um Cristal Líquido Liotrópico." Universidade de São Paulo, 1996. http://www.teses.usp.br/teses/disponiveis/43/43133/tde-03122013-150921/.
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Na fase isotrópica de um cristal líquido liotrópico induziu-se uma birrefringência a partir de gradientes de velocidades. Os gradientes são produzidos pelo movimento de queda de uma placa plana no interior da amostra. O diagrama de fases (da mistura KL/DeOH/H2O) em função da temperatura apresenta duas fases lamelares (L) limitando a fase isotrópica(I). A perturbação mecânica introduzida na fase isotrópica da mistura induz uma birrefringência que relaxa com um tempo característico, , da ordem de 10 POT -2s. A birrefringência induzida por gradientes de velocidades na fase isotrópica é tratada como um processo de difusão de ordem no interior da mistura. Nesta proposição determina-se, experimentalmente, um comprimento característico, l (que informa sobre as propriedades de correlação entre as micelas), a partir de medidas de transmitância em função do tempo. Esse parâmetro é da ordem de 10 POT -5 cm. O comportamento de e l em função da temperatura indica a existência de uma fase nemática virtual (FNV) no domínio isotrópico.The flow birefringence induced in a lyotropic mixture in the isotropic phase was produced by means of velocities gradients. The gradients are produced by the movement of a plate inside the sample. As a function of temperature, the isotropic phase(I) is surrounded by two lamellar(L) phases in the phase diagram (mixture KL/DeOH/H2O). The shear flow produced by a perturbation in the isotropic phase induces a birefringence which relaxes with a typical relaxation time, ~10-2 s. The birefringence induced by velocities gradients is treated by means of an order diffusion process into the mixture. In this approach a characteristic length, l, (which informs about the correlation properties between the micelles) is experimentally obtained with the measurement of the transmittance as a function of the time. This parameter is about 10-5cm. The behavior of and 1: versus temperature indicate the existence of a virtual nematic phase(VNP) in the isotropic phase.
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Tidu, Aurélien. "Synthèse d'une cornée artificielle à base de collagène I." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066472/document.
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L'objectif du projet est la synthèse d'une cornée artificielle biocompatible à base de collagène de type I extrait et purifié à partir de tendons de queues de rats. La synthèse utilise les propriétés mésogènes (cristal-liquides) de la molécule de collagène ainsi qu'une transition sol-gel mimant l'étape de fibrillogenèse qui se déroule in vivo. Des solutions acides de collagène (500 mM en acide acétique) sont dyalisées contre des solutions de diverses concentrations en acide acétique et en acide chlorhydrique puis concentrées jusqu'à 90 mg/mL. Les phases cristal-liquides données par les différentes conditions physico-chimiques sont analysées par microscopie à lumière polarisée et par génération de seconde harmonique. L'une des conditions permet d’obtenir une phase dite en contreplaqué, ce qui est l’organisation des lamelles de fibrilles de collagène dans la cornée.Analysée par microscopie électronique à transmission, la structure des matrices obtenues après fibrillogénèse présente des domaines en contreplaqué indiquant une conservation et une stabilisation de l’organisation cristal-liquide d'origine. L’organisation obtenue est proche de celle du stroma cornéen. Par une optimisation des conditions physico-chimiques, les matrices synthétisées présentent une transparence proche de 90 % et possèdent de bonnes propriétés mécaniques avec un module d’Young proche de 1 MPa. Des cultures cellulaires effectuées sur les matrices transparentes montrent qu’elles sont un très bon support pour la culture de cellules cornéennes, en particulier des cellules épithéliales. Tous ses résultats confortent la méthode utilisée et les essais in vivo constituent l’étape suivanteIn view to generate artificial corneas, dense transparent collagen type-I scaffolds were synthesized exploiting the intrinsic liquid crystals properties of collagen molecules. 3 mg/mL collagen solutions in 500 mM acetic acid were dialyzed against a solution of precise concentrations in acetic and hydrochloric acid. When concentrated, solution provided a liquid-crystal organization resembling plywood, which is the organization of the collagen fibrils in the cornea. This was verified by polarized light and second harmonic generation microscopy experiments. In parallel these collagen solutions were also concentrated by centrifugation-filtration up to 90 mg/mL. The concentrated solutions were pressed into cornea-like shape and submitted to ammonia vapor in order to induce the fibrillogenesis of collagen. The result is a transparent dense fibrillated collagen matrix (transparency 90 %). Transmission electron microscopy revealed that fibrils kept the organization of the concentrated solution. Using a custom made device, mechanical tests showed that the Young modulus reached 900kPa. Human donor limbal explants were sewed on top of the scaffolds and cultured for 14 days. Optical microscopy and immunocytochemical analysis showed the development of an epithelium with characteristics of corneal epithelial cells. Preliminary experiments showed that keratocytes could be successfully inserted during the synthesis process. Thus, the results show the viability of the process of fabrication, and the following step is the in vivo experiment
Books on the topic "Liquid cristal"
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Liquid crystals: Nature's delicate phase of matter. 2nd ed. Princeton, N.J: Princeton University Press, 2002.
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Liquid crystals: Nature's delicate phase of matter. Princeton, N.J: Princeton University Press, 1990.
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NATO Advanced Research Workshop on Defects, Singularities, and Patterns in Nematic Liquid Crystals: Mathematical and Physical Aspects (1990 Orsay, France). Nematics: Mathematical and physical aspects. Dordrecht: Kluwer Academic, 1991.
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service), INSPEC (Information, and Knovel (Firm), eds. Physical properties of liquid crystals: Nematics. London: IEE, 2001.
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Donald, A. M. Liquid crystalline polymers. Cambridge [England]: Cambridge University Press, 1992.
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Chandrasekhar, S. Liquid crystals. 2nd ed. Cambridge [England]: Cambridge University Press, 1992.
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Jacques, Prost, ed. The physics of liquid crystals. 2nd ed. Oxford: Clarendon Press, 1995.
Find full textBook chapters on the topic "Liquid cristal"
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Siebert, S., and G. Schumacher. "Application of Interval Arithmetic to Solve a Problem in Liquid-Cristal Modelling." In European Consortium for Mathematics in Industry, 271–74. Wiesbaden: Vieweg+Teubner Verlag, 1992. http://dx.doi.org/10.1007/978-3-663-09834-8_55.
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"A.1. L’alternative cristal – liquide surfondu." In Le verre, 297–318. EDP Sciences, 2020. http://dx.doi.org/10.1051/978-2-7598-0248-7-049.
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"A.1. L’alternative cristal – liquide surfondu." In Le verre, 297–318. EDP Sciences, 2020. http://dx.doi.org/10.1051/978-2-7598-0248-7.c049.
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"La lucha de clases." In Music for Unknown Journeys by Cristian Aliaga, edited by Benjamin Bollig, 110–11. Liverpool University Press, 2021. http://dx.doi.org/10.3828/liverpool/9781800348097.003.0048.
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What she read/All heady books/ She’d sit and prophesise/ (It took a tattooed boy from Birkenhead/ To really really open her eyes). The Smiths Las naves inmensas retumban ahora en el silencio. El espíritu de los alborotadores, los sufrientes, los que inspiraron a Marx, ha caído en el olvido junto a las maquinarias que los ataban. Todo lo sólido se desvanece en el aire, dijo, y advirtió sobre aquello que se sigue desvaneciendo en nosotros. Siglos amargos, revoluciones pervertidas, libros sagrados reducidos a ceniza. El siglo XXI liquida a los restos de la clase obrera con la incitación al suicidio. Las fábricas son refugios y no panópticos abandonados. Olvidados de luchar, ardientes contra el enemigo omnipotente e invisible, queda el desafío de recordar el grito y la ira. Cruzado el cuerpo por la desilusión, bebemos frente a la fábrica desahuciada, unidos por nada. Trabajadores despedidos de todo, perros que sueñan con carne, ociosos a la fuerza ante los diques repintados. Hasta caer, bebemos líquidos que saben a lo perdido, inmóviles en terrazas lustradas donde se simula la paz y la lucha de clases es el título del espectáculo de la verdad póstuma....
Conference papers on the topic "Liquid cristal"
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Sboui, Fakher, Jan Machac, Lassaad Latrach, and Ali Gharsallah. "Triple Band Tunable SIW Cavity Antenna with Cristal Liquid Materials for Wireless Applications." In 2019 IEEE 19th Mediterranean Microwave Symposium (MMS). IEEE, 2019. http://dx.doi.org/10.1109/mms48040.2019.9157250.
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Kazak, A. V., N. V. Usol'tseva, V. V. Bykova, A. S. Semeikin, and S. G. Yudin. "Influence of meso-substituted porphyrins derivatives molecular structure on their liquid-cristal properties and supramolecular organization in floating layers." In 2010 20th International Crimean Conference "Microwave & Telecommunication Technology" (CriMiCo 2010). IEEE, 2010. http://dx.doi.org/10.1109/crmico.2010.5633001.
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Trotta, Gianluca, Vincenzo Bellantone, Rossella Surace, and Irene Fassi. "Effects of Process Parameters on the Properties of Replicated Polymeric Parts." In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-71049.
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The increasing demand for small and even micro scale parts is boosting the development of reliable micro system technologies. Micro-fabrication process capabilities should expand to encompass a wider range of materials and geometric forms, by defining processes and related process chains that can satisfy the specific functional and technical requirements of new emerging multi-material products, and ensure the compatibility of materials and processing technologies throughout these manufacturing chains. Micro injection moulding is the process of transferring the micron or even submicron precision of microstructured metallic moulds to a polymeric products. It represents one of the key technologies for micro manufacturing because its mass production capability and relatively low production cost. Polymers have relatively low cost, and offer good mechanical and thermal strength, electrical insulation, optical transparency, chemical stability and biocompatibility. In this work the authors investigate the micro injection moulding process parameters on the overall quality of a miniaturized dog-bone shaped specimen. The aim of the experimentation is to calibrate the process and set the machine for the correct filling of the component. A set of injection parameters are selected for study by experimental plan and simulation tool and then discussed. Simulation results are used to better understand the polymer flow behaviour during the filling phase. A commercial software is used and input data, collected during the micro injection moulding process, are included using as performance indicators flow front position and moulded mass. Process simulation can provide, at the present time, mostly qualitative input to the designer and process engineer. Two different polymers materials are tested and evaluated in relation to the process replication capability: Polyoxymethylene (POM) and Liquid Cristal Polymer (LCP). Finally, the moulding factors with significant statistical effects are identified. The holding pressure and holding time for POM and the holding pressure and injection velocity for LCP show the highest influence on achieving high part mass.
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Leroux, T. "Techniques d'adressage de matrices à cristaux liquides." In Optoélectronique (Volume 1). Les Ulis, France: EDP Sciences, 1990. http://dx.doi.org/10.1051/sfo/1990005.
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Garandet, Jean-Paul. "Croissance cristalline en phase liquide : éléments théoriques." In Élaboration et caractérisation des cristaux massifs et en couches minces pour l'optique. Les Ulis, France: EDP Sciences, 2003. http://dx.doi.org/10.1051/bib-sfo:2002809.
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Le Pesant, J. P. "Les cristaux liquides ferroélectriques et leur utilisation en optoélectronique." In Optoélectronique (Volume 1). Les Ulis, France: EDP Sciences, 1990. http://dx.doi.org/10.1051/sfo/1990004.
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