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Nitrations of viscose rayonAllen, Ralph Wilson January 1942 (has links)
An examination of the experimental data will give the following generalizations.
The stability tests indicate that the same type of acid hydrolysis of the glucose linkages occurs giving unstable, short-chain nitrates whenever rapid, harsh esterification is undertaken. This instability naturally prohibits use of such products as smokeless powder.
From the results of this investigation, it seems that any continuous type of acidic nitration of viscose rayon for use in powder bags or guncotton would be highly impractical. / M.S.
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Determination of the relation between the particle size of viscose and the physical properties of the rayon produced: development of a practical method for measuring the change of particle sizeSchneider, John Matthew January 1932 (has links)
M.S.
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An investigation into possible sources of pulp with particular reference to their use in the production of rayonMorison, Charles Ridgely White January 1930 (has links)
M.S.
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The effect of certain detergents on the service qualities of a selected cotton fabric and a spun viscose rayon fabricGates, Ruth Elizabeth. January 1948 (has links)
Call number: LD2668 .T4 1948 G3 / Master of Science
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Poplar oxidoreductases involved in the oxidative stress response : a crystallographic snapshot towards the understanding of the catalytic mechanism / Etude cristallographique d’oxydoréductases impliquées dans la réponse au stress oxydatif chez le peuplier en vue de la compréhension de leur mécanisme catalytiqueKoh, Cha San 29 May 2008 (has links)
La structure de trois oxydoréductases (la glutathion peroxydase (Gpx), la thiorédoxine (Trx) et la glutarédoxine (Grx)) de Populus trichocarpa × deltoides (le peuplier) a été caractérisée par diffraction des rayons X. Les Gpxs forment un groupe d’enzymes qui régulent la concentration des espèces réactives de l'oxygène (ROS) dans les cellules, et qui les protègent des effets d’un stress oxydant. Contrairement à leurs homologues d’origine animale, les Gpxs végétales ne dépendent pas du glutathion (GSH) mais des Trx pour leur fonctionnement. Dans cette étude, j'ai résolu les structures des formes réduite et oxydée de la Gpx5 de peuplier et montré que des changements conformationnels drastiques sont nécessaires pour passer d’une forme à l’autre. Les Trxs régulent diverses protéines cibles par la réduction de leur pont disulfure. Mon objectif était de comprendre le mécanisme catalytique d’une nouvelle isoforme, la PtTrxh4, dont la capacité à accepter des électrons de la Grx a été récemment démontrée. Cette PtTrxh4 contient trois cystéines, la première localisée dans une extension en position N-terminale (Cys4) et deux situées dans le site actif classique (WC1GPC2) de la Trx. Les résolutions des structures de l’enzyme sauvage et du mutant C4S m’ont permis de proposer un mécanisme catalytique en quatre étapes en accord avec les études enzymatiques. Les Grxs sont des protéines qui utilisent des électrons du GSH en particulier pour catalyser des réactions d'échange de thiol-disulfure. Ici, je présente la structure de la PtGrxS12 (en complexe avec le GSH), la première structure de la Grx végétale de sous-classe 1 ayant un site actif de motif atypique 28WCSYS32. / Three oxidoreductases (glutathione peroxidase, GPX; thioredoxin, Trx and glutaredoxin, Grx) from Populus trichocarpa × deltoides (poplar tree) were characterized using X-ray crystallography approach. GPXs are a group of enzymes that regulate the levels of oxygen species in cells, and protect them against oxidative damage. In this study, I have determined the crystal structures of the reduced and oxidized form of poplar GPX5 (PtGPX5). Comparison of both redox structures indicates that a drastic conformational change is necessary to bring the two distant cysteine residues together to form an intramolecular disulfide bond. Trxs regulate various protein partners through the thiol-disulfide(s) reduction. The aim of this study is thus to precisely describe the catalytic mechanism of a new isoform of Trx, PtTrxh4, since it has been demonstrated recently to be reduced by Grx. PtTrxh4 contains three cysteines; one localized in an N-terminal extension (Cys4) and two in the usual Trx active site (WC1GPC2). Two crystal structures of PtTrxh4 solved in this study, wild-type and C61S mutant, allow us to propose a four-step disulfide cascade catalytic mechanism in accordance with enzymatic studies. Grxs are highly conserved redox-proteins that utilize electrons from GSH particularly to catalyze thiol-disulfide exchange reactions. Here, I present the structure of glutathionylated PtGrxS12, the first structure of plant Grx of subclass 1 with an atypical 28WCSYS32 active site. Protein structures solved here shed lights to our understanding of the redox mechanism in plant and to the enzyme-substrate interactions.
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Métodos de ensayo de las fibras artificialesRiba Arderiu, Jordi 01 January 1949 (has links)
En este trabajo se investigan las peculiaridades del comportamiento elástico de los filamentos de rayón, que difiere grandemente del de las fibras naturales.Es un resumen de una extensa labor de recopilación bibliográfica, de investiga-ción y de ensayo realizada en 1949 por el autor en una fábrica de tejidos de seda y de rayón de Palma de Mallorca de la cual era Director Técnico. Basándose en el material reunido, el autor pronunció una conferencia sobre este tema en una Velada Técnica organizada por la Asociación Nacional de Ingenieros de Industrias Textiles, el 30 de Mayo de 1949. Un resumen de lo expuesto en ella fue publicado más tarde, en forma de articulo en la revista Ingeniería Textil (nº 80, Noviembre - Diciembre 1949). Se adjunta un ejemplar de la misma.En la época en que se realizó este estudio, aunque ya era corriente en la industria el uso de los distintos tipos de rayón, aún no habían sido bien estudiadas muchas de las propiedades mecánicas de éstos. En particular, la noción de "tiempo" contenida en los conceptos de "alargamiento diferido" y "recuperación diferida" (elasticidad diferida) así como su gran influencia sobre los resultados de las mediciones dinamométricas, constituían una novedad en aquellas fechas.La posterior aparición de las fibras sintéticas y de ciertas materias plásticas, ha si-tuado en primer plano todos estos conceptos que ya habían alcanzado importancia con las fibras artificiales. Los conceptos expresados por el que suscribe en la conferencia y el artículo mencionados, han sido más tarde confirmados y utilizados por otros autores siendo actualmente de uso común.Los métodos estadístico-matemáticos, que habrían resultado muy apropiados para determinar el grado de significación de los ensayos efectuados, no fueron utilizados en este estudio ya que no eran todavía usuales en nuestro país en la época en que fué rea-lizado. / The present paper is a report on the peculiarity of elastic behavior in rayon fibers, which differs very much from such behavior in natural fibers. This research is the summary of extensive work on the bibliography, research and experimental work done by the author in 1949 in a silk and rayon fabric manufactory in Palma de Mallorca, where the author was the technical director. Based on this research, the author gave a conference on the subject in a Technical Ses-sion organized by the Asociación Nacional de Ingenieros de Industrias Textiles (Na-tional Association Engineers of Textile Industries, Spain), on 30 May 1949. The con-ference material was published later as an article in the journal "Ingeniería Textil" (Nº 80, November - December 1949). In spite of the fact that the industry habitually used several types of rayon when this study was originally done, the mechanical properties of these fibers have still not been adequately studied. In particular, the notion of "time" embedded in the concepts of "deferred extension" and "deferred recovery" (deferred elasticity), and their significant influence on the results of dynamometric measures, were novel at that time.The later appearance of synthetic fibers and plastic materials foregrounded these con-cepts, which have remained important in the field of artificial fibers. The concepts ex-amined by the author have lately been confirmed and used by other researchers and are currently in common use.The statistical-mathematical methods that would have been very appropriate for de-termining the signification of the tests done at that early period had not been used in the original study because they were unusual at that time and in our country. This research was motivated by a number of problems and special difficulties that in-volve the manipulation of artificial fibers, mainly rayon.Many phenomena that cause important defects often seem to have no logical explana-tion and frequently induce one to think that the same causes do not always correspond to the same effects. However, that is not true. What in fact is the case is that artificial fibers are recent in industry, and their properties greatly differ from the concepts and norms considered basic and definitive until now. In particular, the concept of "elasticity" is too simple and primitive to explain the var-ied phenomena that take place in artificial fibers submitted to stresses of different kinds. In this article, we propose to enlarge this concept, placing a special emphasis on the relations between elasticity and the factors time and hygrometric state.
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Identification and characterization of rayon in women's dresses of the 1920s and 1930sLewarne, Alicia Clare Unknown Date
No description available.
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Identification and characterization of rayon in women's dresses of the 1920s and 1930sLewarne, Alicia Clare 11 1900 (has links)
The use of rayon in 1920s and 1930s garments confronts conservators with new challenges: definitive fibre identification involves more than basic microscopy and treatment can be difficult with little available research on early rayon and its conservation. Rayon is expected to degrade similarly to other cellulosic fibres; however, since it is a regenerated fibre, rayon is at risk of doing so at a faster rate. The purpose of this research was to develop and test a protocol for the identification of viscose and cuprammonium rayon and to determine whether early rayon dresses have condition issues at this time. Polarizing microscopy, hot-stage microscopy, acetone solubility and relative fibre refractive index were explored as fibre identification techniques, resulting in the development of a rayon identification scheme. 1920s and 1930s rayon dresses were surveyed for condition and it was determined that dresses in this sample have limited condition issues at this time.
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What is special about Japan? technology transfer and corporate structure in pre-war Japan /Frankl, Jennifer Lea. January 1996 (has links)
Thesis (Ph. D.)--University of California, Berkeley, 1996. / Includes bibliographical references (leaves 107-108).
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Détection de collision par lancer de rayon : La quête de la performance / Ray-traced collision detection : Quest for performanceLehericey, François 20 September 2016 (has links)
La détection de collision est une tâche essentielle pour la simulation physique d’environnements virtuels. De nos jours, la détection de collision est l’un des goulets d’étranglement calculatoire dans les applications de réalité virtuelle dû à la complexité des environnements que l’on souhaite simuler et par la contrainte d’interaction en temps-réel. Nous avons concentré nos travaux sur la seconde étape de la détection de collision (narrow-phase) dans laquelle les tests de collisions sont effectués sur des paires d’objets. Contrairement à la première étape, les tests de collisions sont effectués sur des versions détaillées des modèles géométriques et sont donc très sensible au niveau calculatoire à la complexité géométrique de ceux-ci.Cette thèse vise à améliorer les performances de la détection de collision lors de l’utilisation d’objets géométriques complexes (formes représentées par un maillage, éventuellement non-convexe et/ou déformable). Nos méthodes permettent d’accélérer le calcul de la narrow-phase. Les algorithmes proposés peuvent être implémentés sur GPU pour profiter de leur puissance de calcul et ainsi améliorer les performances.Pour réaliser la narrow-phase, nous proposons un pipeline adapté à une implémentation GPU. Celui-ci permet de réaliser la narrow-phase à l’aide d’algorithmes basés lancer de rayon. Notre méthode repose sur un principe commun où tous les tests de collision sont effectués par lancer de rayon à partir des sommets des objets. Cette généricité nous permet de réaliser les tests sur des maillages ayant n’importe quelles propriétés (rigide ou déformable, convexe ou non-convexe). Les algorithmes de lancer de rayon utilisés étant choisis en fonction des propriétés des objets pour optimiser les performances.Nous avons généralisé la méthode de détection de collision utilisée pour supporter, en plus des objets volumiques, des objets surfaciques (tels que des tissus). Cette méthode est compatible avec le pipeline proposé et permet de réaliser des tests de collisions entre n’importe quelle combinaison d’objets.De plus, nous proposons d’exploiter la cohérence temporelle pour améliorer les performances. Le résultat de la détection de collision est généralement très semblable entre deux pas de temps successifs. Suite à cette observation, nous proposons un algorithme de lancer de rayon itératif qui intègre le résultat du pas précédent pour exploiter cette cohérence temporelle. Cet algorithme peut être utilisé conjointement avec des algorithmes de lancer de rayon standard. Il permet de remplacer certains tests unitaires pour mettre à jour de manière incrémentale le résultat de la détection de collision. L’algorithme de lancer de rayon itératif est ajouté au pipeline en tant qu’alternative aux autres algorithmes de lancer de rayon et est utilisé prioritairement dû à son faible coût calculatoire. / Collision detection is an essential task for physical simulation of virtual environments. Nowadays, collision detection is one of the main bottleneck of virtual reality applications. This is due to the complexity of the environments we want to simulate and the real-time interaction constraint. We have concentrated our work on the second phase of collision detection, the narrow-phase, in which collision queries are performed on pairs of objects. Contrary to the first phase of collision detection, collision queries are performed on the full representation of the objects (with all details) and are thus sensible to the geometric complexity of the objects in term of computation time.This thesis is aimed to improve the performances of collision detection when using geometrically complex objects (represented with triangle meshes, potentially non-convex and deformable). Our methods are able to reduce computation times. Our proposed algorithms can be implemented on GPU to take advantage of their computational power and thus further improve the performances of our methods.To implements our narrow-phase, we propose a pipeline which is adapted for GPU execution. This pipeline perform collision detection with ray-tracing algorithms. Our methods rely on a shared principle where all collision queries are performed by casting rays from the vertices of the objects. This genericity allow us to perform collision detection on triangle meshes with any properties (rigid or deformable, convex or non-convex). The ray-tracing algorithms used are dynamically selected depending on the properties of the objects to improve the performances.We have generalized the collision detection method we use in our pipeline to handle, in addition to volumetric objects (represented by their surface), surface objects (such as cloth). This method is compatible with our pipeline and allow us to perform collision detection with any combination of volumetric and surface objects.Furthermore, we propose to exploit temporal coherency to improve performances. The result of collision queries (contact points) are generally similar between successive time-step. Starting from this observation, we propose a ray-racing algorithm which use the result of the previous time-step to exploit this temporal coherency. This ray-tracing algorithm can be used in conjunction to standard ray-tracing algorithms. It is used to replace standard ray-tracing algorithms in specific condition to update the result of the previous time-step instead of computing it from scratch. The iterative ray-tracing algorithm is added in our pipeline as an alternative to other ray-tracing algorithms and is used in priority due to his lower computational cost compared to other algorithms.
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