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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Índices de conforto térmico para ovinos Santa Inês de diferentes cores de pelame em condições de pastejo / Critical levels of thermal confort for Santa Inês sheep under grazing at Agreste Region at Pernambuco State

NEVES, Maria Luciana Menezes Wanderley 20 February 2008 (has links)
Submitted by (lucia.rodrigues@ufrpe.br) on 2017-05-09T14:25:34Z No. of bitstreams: 1 Maria Luciana Menezes Wanderley Neves.pdf: 498925 bytes, checksum: 5d70ed737f5d134b7425af6efdbc2847 (MD5) / Made available in DSpace on 2017-05-09T14:25:34Z (GMT). No. of bitstreams: 1 Maria Luciana Menezes Wanderley Neves.pdf: 498925 bytes, checksum: 5d70ed737f5d134b7425af6efdbc2847 (MD5) Previous issue date: 2008-02-20 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The objectives of this work were to determine the best physiological parameter indicator of thermal stress in Santa Inês sheeps, to verify coat color influence on tolerance to heat, to determine the most adequate thermal comfort index for these animals under grazing conditions, and to estimate the critical values of comfort index for short hair Santa Inês breed based on the physiological parameters. The experiment was conducted from January to April in agreste region, of Pernambuco state. The rectal temperature (RT), respiratory frequency (RF), and coat surface temperature (CST) were evaluated three times a week in the morning and in the afternoon. The environment was monitored daily, in a meteorological station installed next to the paddock. The measures for regression and correlation analysis among variables were obtained from 15 Santa Inês sheeps with, five animals for each color: white, chestnut, and black. The obtained results showed that the RF was the best physiological parameter for thermal stress. Thermal comfort index (TCI) and the black globe-humidity index (BGHI) were more accurate than the temperature and humidity index (THI) in the heat stress evaluation on Santa Inês sheep. The correlation and regression results suggested a small superiority of the white animals than the others in the heat tolerance. Basing on the RT, the estimated critical values for white, chestnut, and black sheeps were, respectively, 80.0, 79.5, and 78.9 for THI, 92.8, 91.4, and 90.5 for BGHI, and 46.3, 45.5, and 44.5 for TCI. Basing on the RF, the estimated critical values for white, chestnut and black sheeps were, respectively, 76.3; 75.2 and 75.3 for THI, 86.0, 84.0, and 84.2 for BGHI, and 38.0 for TCI in the animals of the three coat colors. / Os objetivos deste trabalho foram determinar o melhor parâmetro fisiológico indicador de estresse térmico em ovinos da raça Santa Inês, o índice de conforto térmico mais adequado para estes animais em criação a pasto e estimar os valores críticos dos índices de conforto com base nos parâmetros fisiológicos. O experimento foi conduzido de janeiro a abril na região agreste de Pernambuco. Os parâmetros temperatura retal (TR), freqüência respiratória (FR) e temperatura da superfície do pelame (TSP) foram avaliados três vezes por semana nos períodos da manhã e da tarde. O ambiente foi monitorado diariamente, por intermédio de uma estação meteorológica instalada ao lado do piquete. As medidas para as análises de regressão e correlação entre as variáveis foram obtidas de 15 ovinos da raça Santa Inês, sendo cinco de cada cor: branca, castanha e preta. Os resultados obtidos evidenciaram que a FR foi o melhor parâmetro fisiológico indicador de estresse térmico e que o índice de conforto térmico (ICT) e o índice de temperatura do globo e umidade (ITGU) foram mais precisos que o índice de temperatura e umidade (ITU) na avaliação do estresse 22 pelo calor em ovinos dessa raça. Observou-se pequena superioridade dos animais brancos em relação aos demais quanto a tolerância ao calor. Baseando-se na TR os valores críticos estimados para os ovinos brancos, castanhos e pretos foram, respectivamente de 80,0; 79,5 e 78,9 para o ITU; 92,8; 91,4 e 90,5 para o ITGU e 46,3 45,5 e 44,5 para o ICT. Baseando-se na FR, os valores críticos estimados para os ovinos brancos, castanhos e pretos foram, respectivamente de 76,3; 75,2 e 75,3 para o ITU; 86,0; 84,0 e 84,2 para o ITGU e 38,0 para o ICT nos animais das três cores.
82

Estrutura e desenvolvimento de sementes de Paullinia L. (Sapindaceae) / Seed structure and development of Paullinia L. (Sapindaceae)

Polo, Sandra Heliany Obando 08 January 2006 (has links)
Orientadores: Sandra Maria Carmello-Guerreiro, Pedro Acevedo-Rodriguez / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-07T06:23:56Z (GMT). No. of bitstreams: 1 Polo_SandraHelianyObando_M.pdf: 4995213 bytes, checksum: c9f5b62469e312e4dcd4138e126bbd72 (MD5) Previous issue date: 2006 / Resumo: No presente trabalho foram estudadas a ontogenia, morfologia e anatomia das sementes de algumas espécies do gênero Paullinia L. (Sapindaceae), coletadas em diversas áreas dos estados de São Paulo, Rio de Janeiro e Paraná. Para fins morfológicos e conceituais foi estudada a ontogênese da estrutura carnosa na semente de Paullinia trigonia Vell. De forma a avaliar a importância dos caracteres da semente para fins taxonômicos foram estudadas a morfologia e anatomia do envoltório seminal, cicatriz e estrutura carnosa em sementes maduras de nove espécies do gênero Paullinia: P. elegans Cambess., P. spicata Benth., P. cupana Kunth, P. carpopodea Cambess., P. meliaefolia A. L. Juss., P. coriacea Casar., P. cristata Radlk., P. racemosa Wawra e P. trigonía Vell., pertencentes a cinco das treze seções estabelecidas por Radlkofer. Os resultados indicaram que no referente à ontogenia da estrutura carnosa em P. trigonia Vell., o tegumento externo participa da formação da estrutura carnosa em duas regiões da semente, na porção basal da rafe e o na área próxima da micrópila. O funículo não contribui na formação da estrutura carnosa. Essa estrutura carnosa foi denominada sarcotesta e o termo arilo, como tem sido descrito não foi usado. Aspectos relacionados com o desenvolvimento da estrutura carnosa, da flor estaminada e pistilada, foram comparados e discutidos com outros representantes do gênero e a família Sapindaceae. As características morfológicas das sementes apresentam notáveis diferenças entre as espécies. Três caracteres em conjunto permitem distinguir facilmente as espécies: l.Tamanho e forma estrutural da semente. 2.Morfologia da sarcotesta (termo usado para definir o tipo de estrutura carnosa nas nove espécies examinadas), proporção que cobre a semente e fissuras principalmente na região da anti-rafe. 3.Forma e tamanho da cicatriz, lóbulos na região da rafe e anti-rafe, dimensão e tipo de fusão das projeções e grau de constrição na área intermédia entre os lóbulos e as projeções da cicatriz. Os caracteres anatômicos de maior utilidade para diferenciar as espécies foram apresentados pelo envoltório seminal: comprimento do estrato exotestal e número de camadas e dimensões da mesotesta. Os caracteres analisados não forneceram indícios de um agrupamento apoiando as seções propostas por Radlkofer, mais são caracteres de utilidade potencial na taxonomía e identificação das espécies do gênero / Abstract: In this work were studied the ontogeny, morphology and anatomy of the seeds of some species of the genus Paullinia L. (Sapindaceae), collected in severa I areas in the states of São Paulo, Rio de Janeiro and Paraná. The ontogeny of the fleshy structure of the seed of Paullinia trigonia Vel!. was study for conceptual and morphological purposes. In order to evaluate the importance of the characters of the seed for taxonomic value, the morphology and the anatomy of the seed coat, scar, and fleshy structure were studied in mature seeds of nine species of the genus Paullinia: P. elegans Cambess., P. spicata Benth., P. cupana Kunth, P. carpopodea Cambess., P. meliaefolia A. L. Juss., P. coriacea Casar., P. crista ta Radlk., P. racemosa Wawra and P. trigonia Vell., species belonging to five out of thirteen sections established by Radlkofer. The results indicated that in the ontogeny of the fleshy structure, the outer integument participates in the formation of the fleshy structure in two regions in the seed: in the basal portion of the raphe and in the area near the micropyle. The funicle does not contribute in the formation of the fleshy structure. The fleshy structure was definited as sarcotesta. The term aril referring to this white structure is not used in our work. Aspects relating to the development of the fleshy structure and of the staminate and pistilate flowers, are compared and discussed with other representatives of the genus and the Sapindaceae family. The morphologic characteristics of the seeds present remarkable differences between the species. Three characters altogether allow distinguishing the species easily: 1. Structural size and shape of the seed. 2. Morphology of the white fleshy structure, characterized here as sarcotesta for nine species examined, proportion that covers the seed, and fissures mainly in the anti-raphe region. 3. Shape and size of the scar, lobules in the raphe and anti-rafe regions, dimension and type of fusion of the projections, as well as the degree of the constriction in the intermediate area between the lobes and the projections of the scar. The most useful anatomical characters to differentiate the species are the ones presented in the seed coat: dimension of the exotestal stratum and number of layers and dimensions of the mesotesta. The characters analyzed here do not offer indications of a clustering supporting the sections proposed by Radlkofer, but they are characters of potential utility in the taxonomy and identification of the species of the genus / Mestrado / Mestre em Biologia Vegetal
83

Avaliação do desempenho de aglomerante a base de gesso com cimento portland de alto forno e silica ativa / Perfomance assessment of gypsum cement based rendering materials containing portland blast-furnce slag cement and condensed silica fume

De Milito, Jose Antonio 02 July 2007 (has links)
Orientador: Gladis Camarini / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-09T18:12:28Z (GMT). No. of bitstreams: 1 DeMilito_JoseAntonio_D.pdf: 60807018 bytes, checksum: d77cec46bea9822138fd4024fad50842 (MD5) Previous issue date: 2007 / Resumo / Resumo: O gesso é um aglomerante que tem sido muito empregado em revestimento de paredes. Apresenta um bom desempenho, é econômico e de fácil aplicação, mas limitado ao uso interno devido a sua sensibilidade à água. Algumas tentativas têm sido realizadas para melhorar a sua utilização em ambientes sujeitos à umidade. Neste sentido, pesquisas avançam na tentativa de empregar diferentes adições como resinas epóxi, polímeros, cimentos, escórias, impermeabilizantes, entre outros. O objetivo desta tese foi avaliar o desempenho das misturas de gesso com cimento Portland de Alto Forno e sílica ativa nos revestimentos internos e externos sujeitos à umidade. Para isso verificaram-se as propriedades macroscópicas das misturas por meio de ensaios físicos, químicos, físico-químicos e também a avaliação microestrutural utilizando a microscopia eletrônica de varredura. As misturas foram aplicadas em revestimentos de painéis de alvenaria de blocos de concreto e observados visualmente por um período de cinco anos. Além da observação visual foi verificada a resistência de aderência das misturas aplicadas internamente e externamente. Dos resultados obtidos observou-se uma possível coexistência entre o gesso e o cimento e que a adição de sílica ativa na mistura reduz a formação de etringita, principalmente nos revestimentos externos, sujeitos à umidade. A adição de cimento Portland melhora na abrasão e perda de massa, mesmo em idades mais avançadas. Assim, devido ao elevado custo de algumas adições, e as dificuldades de trabalhar com outros tipos de adição na obra, a adição de cimento Portland e sílica ativa ao gesso permitem uma melhoria de resistência, obtendo um revestimento de baixo custo e de fácil manuseio. / Abstract / Abstract: Plaster of Paris is a binding material being used in masonry as a plaster finish coat. Despite being economical, having good performance as and ease with wich it is applied in building, its use is limited to indoors. Some attempts has been made to improve its performance in external environment. In that sense, researches advance in the attempt at using several admixtures like epoxy resins, polymers, cements slags, waterproofing materials among other things. The objective of this thesis is to assess the performance of certain mixtures of rendering material containing plaster of Paris, slag cement and condensed silica fume when applied in the internal and external plaster finish coat. The macroscopic properties of the mixtures were analyzed through physical and chemical tests and also in SEM. Mixtures were applied on coatings of brick and mortar and visually inspected within five years. Bond strengths of the mixtures were measured, both in internal and external walls. Results showed compatibility between plaster of Paris and slag cement and that presence of condensed silica fume in the mixture reduced the formation of etringite, especially in the external coatings. The addition of Portland blastfurnace slag cement reduced the abrasion and the loss of mass, even in older ages. Therefore, due to the high cost of some admixtures, and the difficulty in working with other kinds of admixtures in the construction sites, the mentioned additions to the plaster rendering allow a mechanical strength improvement, thus resulting in low cost and good workability of the plaster finish coat. / Doutorado / Edificações / Doutor em Engenharia Civil
84

Características tricológicas e fisiológicas de bovinos da raça nelore submetidos a diferentes graus de sombreamento no cerrado brasileiro / Hair coat and physiological characteristics heifers nelore submitted to different shade of degrees in the brazilian cerrado

Costa, Allan Rodrigues da 26 August 2016 (has links)
Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-12T13:58:30Z No. of bitstreams: 2 Dissertação - Allan Rodrigues da Costa - 2016.pdf: 1270616 bytes, checksum: 1073b4396fff855bc87f0fcd0d85da65 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-09-12T13:58:46Z (GMT) No. of bitstreams: 2 Dissertação - Allan Rodrigues da Costa - 2016.pdf: 1270616 bytes, checksum: 1073b4396fff855bc87f0fcd0d85da65 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-09-12T13:58:46Z (GMT). No. of bitstreams: 2 Dissertação - Allan Rodrigues da Costa - 2016.pdf: 1270616 bytes, checksum: 1073b4396fff855bc87f0fcd0d85da65 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-08-26 / This study aimed to evaluate the morphological and physiological characteristics related to thermoregulatory heifers kept in different conditions of shading in the Brazilian cerrado. The research was conducted at Embrapa Beef Cattle in Campo Grande-MS. 16 heifers reared in forest crop livestock integration system (ILPF) and livestock farming (ILP) divided into four paddocks each, the experimental unit picket with two animals were used. The experiment was carried out in three periods (December, January and February) and the experimental design was completely randomized, and the plots were composed by systems (ILP and ILPF) in three collections (December, January and February). The Morphophysiological parameters were coloration of the (CPM) and skin (CPL), the number of hairs per unit area (NP), medium density by (DM), average diameter of hairs (SD) Average hair length ( CP). The pigmentation of the hair coat of heifers showed statistical significance to the ILP and ILPF systems. To characterize the environment, they were collected dry bulb temperature, black globe temperature, dew point temperature, wind speed and relative humidity, the sun and the shade, to determine the following thermal comfort indexes: index temperature and humidity, globe temperature and humidity index, and radiation heat load. The ILP and ILPF systems had environmental conditions that indicate situation of moderate stress the critical and features skin and hair coat of heifers reared in ILP and ILPF systems showed no differences (P 0.05) / Objetivou-se avaliar as características morfofisiológicas relacionadas a termorregulação de novilhas Nelore mantidas em diferentes condições de sombreamento no cerrado brasileiro. A pesquisa foi conduzida na Embrapa Gado de Corte em Campo Grande-MS. Foram utilizados 16 novilhas Nelore criadas em sistema de integração lavoura pecuária floresta (ILPF) e lavoura pecuária (ILP) divididos em quatro piquetes cada, sendo a unidade experimental o piquete com dois animais. O experimento foi realizado em três períodos (dezembro, janeiro e fevereiro) e o delineamento experimental utilizado foi o inteiramente casualizado, sendo as parcelas constituídas pelos sistemas (ILP e ILPF) em três coletas (Dezembro, Janeiro e Fevereiro). Os parâmetros morfofisiológicos avaliados foram coloração dos pelos (CPM) e da pele (CPL), número de pelos por unidade de área (NP), densidade média dos pelos (DM), diâmetro médio dos pelos (DP), comprimento médio dos pelos (CP). A pigmentação do pelame das novilhas apresentou diferença estatística para os sistemas ILP e ILPF. Para caracterização do ambiente, foram coletadas a temperatura de bulbo seco, temperatura de globo negro, temperatura de ponto de orvalho, velocidade do vento e umidade relativa do ar, ao sol e à sombra, para a determinação dos seguintes índices de conforto térmico: índice de temperatura e umidade, índice de temperatura de globo e umidade, e carga térmica de radiação. Os sistemas ILP e ILPF apresentaram condições ambientais que indicam situação de estresse moderado a crítico e as características pele e pelame de novilhas Nelore criadas em sistemas ILP e ILPF não apresentaram diferenças (P˂0,05).
85

Hexamethylene Diisocyanate Homopolymer and Monomer Exposure Assessment and Characterization at an Automobile Manufacturer in the United States

Sivaraman, Karthik Reguram 30 June 2016 (has links)
A variety of paint products are used for their aesthetic and anti-corrosive properties. Isocyanates are consistently found in automobile paint products, particularly in clear coat polyurethane products. Clear coat is typically sprayed via pressurized air by means of an auto-spray robot. In clear coat repair situations, manual, air-powered spray guns are used, and manual spray Operators administer the clear coat material. The isocyanates are a primary anti-corrosive agent in polyurethane products. The Occupational Safety and Health Administration (OSHA) has not established a Permissible Exposure Limit (PEL). The National Institute for Occupational Safety and Health (NIOSH) and American Conference of Governmental Industrial Hygienists (ACGIH) have set Recommended Exposure Limit (REL) and Threshold Limit Value (TLV), respectively. NIOSH recommends a 0.005 parts per million (ppm), 10-hour Time Weighted Average (TWA), and a ceiling exposure of 0.020 ppm in a 10 minute period. Similarly, ACGIH recommends a 0.005 ppm, 8 hour TWA. Automobile manufacturers use clear coats in a variety of ways. Some may use clear coats with blocked isocyanates, or isocyanates that are completely reacted, and others may use clear coat products that allow isocyanates to be liberated during an application, baking, and curing process. The research objective of this study was to characterize exposure, focusing on a single manufacturer’s use of isocyanate-containing clear coats in their Paint Department. A newly evaluated medium (ISO 17734) using di-n-butylamine as a derivative agent, in a denuder tube, was selected instead of NIOSH methods 5521, 5522, and 5525. The ISO evaluated medium was selected to reduce secondary hazard exposure to toluene in impingers. Second, a medium developed by SKC, Inc., called ISO-CHEK®, was not selected because of the short collection time, sensitivity of the medium after collection, and storage and shipping requirements for analysis. Sampling took place over two days, one day for manual spray operations with 2 personal samples from Operators, and 4 area samples collected, and the second day for auto-sprayer Inspectors with 4 personal samples collected. The samples were then analyzed for hexamethylene diisocyanates (HDI) monomer and homopolymer species. The 0.005 ppm, 10 hour TWA; the 0.020 ppm ceiling limit (10 minutes); and the 0.005 ppm 8-hour TWA TLV were not exceeded on either day of sampling. Neither the area nor the personal samples exceeded the 10 hour TWA, ceiling limit, or TLV. In fact, the results had to be recalculated in to parts per billion (ppb). The average exposure for manual spray Operators was 0.052 ppb for the homopolymer, and 0.024 ppb for the monomer species. For auto-spray Inspectors, the average was 0.053 ppb for the homopolymer component and 0.021 ppb for the monomer species. Though the average isocyanate concentration was similar for both Operators and Inspectors, the averages are still below REL and TLV recommendations. These data provided preliminary information regarding the exposure to isocyanates from clear coat use, and also provide context for future evaluation of isocyanate use at this automobile manufacturer. The low concentration of isocyanates could indicate working ventilation systems, liberation of isocyanate species to non-hazardous forms, or low volatilization of isocyanates from the clear coat.
86

Chicken Eggshell Membrane and Cuticle: Insight from Bioinformatics and Proteomics

Du, Jingwen January 2013 (has links)
The chicken eggshell possesses physical and chemical barriers to protect the embryo from pathogens. The avian eggshell cuticle is the outmost layer of the eggshell whose protein constituents remain largely unknown. Since eggs with incomplete or absent cuticle are more susceptible to bacterial contamination, we hypothesize that cuticle protein components play an important role in microbial resistance. In our study, at least 47 proteins were identified by LC/MS/MS in the non-calcified cuticle layer. Similar to Kunitz-like protease inhibitor (also annotated as ovocalyxin-25, OCX-25) and ovocalyxin-32 (OCX-32) were two of most abundant proteins of the cuticle proteins. Some proteins that have antimicrobial activity were also detected in the proteomic results, such as lysozyme C, ovotransferrin, ovocalyxin-32, cystatin, ovoinhibitor. This study represents the first comprehensive report of the cuticle proteome. Since the sequence similarity of the kunitz motif in OCX-25 is similar to that of BPTI, it is predicted that it will have the same trypsin inhibitory and antimicrobial activity against Gram-positive and/or Gram-negative bacteria. In order to test the antimicrobial property and trypsin inhibitor activity of OCX-25, cuticle proteins were extracted by 1N HCl. Antimicrobial activity was monitored using the Bioscreen C instrument; and antimicrobial activity was identified primarily against Staphylococcus aureus. Trypsin inhibitor activity was studied by using a specific trypsin assay, and the assay indicated that the cuticle proteins could inhibit the reaction of trypsin and substrate. Therefore, the current research has provided some insight into the antimicrobial and enzymatic aspects of the cuticle proteins, and its function for egg protection. Eggshell membranes are another important component of the chicken eggshell.Due to its insoluble and stable properties, there are still many questions regarding formation and constituents of the eggshell membranes. The purpose of our study was to identify eggshell membrane proteins, particularly these responsible for its structural features, by examining the transcriptome of the white isthmus during its formation. Bioinformatics tools were applied to analyze the differentially expressed genes as well as their encoded proteins. Some interesting proteins were encoded by the over-expressed genes in the white isthmus during the formation of eggshell membranes, such as Collagen X, and similar to spore coat protein SP75. These proteins may have potential applications. Our study provides a detailed description of the chicken white isthmus transcriptome during formation of the eggshell membranes; it could lead to develop the strategies to improve food safety of the table egg.
87

Studying Transmembrane Helix Interactions in SDS micelles

Qureshi, Tabussom January 2016 (has links)
The importance of interactions between transmembrane domains of integral membrane proteins has been well-established in a range of essential cellular functions. Most integral membrane proteins also possess regions that lie on the exterior of the membrane that may influence the ability of these transmembrane domains to interact. We sought to test this hypothesis by quantifying the energetics of transmembrane helix self-association in the absence and presence of an amphipathic helix that can bind to the membrane surface. The model chosen for this study was the major coat protein (MCP) of M13 bacteriophage, which has an N-terminal amphipathic helix linked to its single transmembrane segment via a flexible linker. Dimerization of both full-length MCP and a peptide containing only the transmembrane domain (MCPTM) was studied by solution NMR in SDS micelles. We found that there was an increase in the apparent dimerization affinity in the absence of the N-terminal helix. However, this increase in apparent affinity could be attributed to differences in detergent-binding properties of the two polypeptides in monomeric versus dimeric states when the empty micelle was considered to be a participant in the dimer dissociation. Preliminary results from the integral membrane protein, p7 of the hepatitis C virus are also presented in this thesis. It has been demonstrated that p7 enhances viral infectivity and accumulation, and that this function may require oligomerization in the membrane. While we encountered limitations due to challenges in the generation of sufficient quantities of pure p7 samples, we were able to perform circular dichroism spectroscopy under conditions that may favor different oligomeric states. These studies suggest that there is a change in the degree of helicity upon oligomerization, and suggest that SDS could be a suitable system to characterize the interactions of the p7 oligomer in the future.
88

Análise da resistência à corrosão de materiais para implantes com revestimento cerâmico de hidroxiapatita / Analysis of the corrosion resistance of materials for implants with ceramic coating of hidroxiapatite

Lisete Maria Florenzano de Mello 17 January 2000 (has links)
Metais são largamente empregados em implantes (endopróteses), principalmente nos que tem finalidade ortopédica. O meio fisiológico representa um meio extremamente agressivo, provocando corrosão que pode resultar em sérios problemas aos pacientes que recebem os implantes. Passou-se a utilizar revestimentos sobre o metal-base de implantes para melhorar a sua resistência à corrosão. Mais recentemente, revestimentos porosos de cerâmica, que permitem ao tecido ósseo um crescimento por entre a porosidade, passaram a ser empregados, pois assim dispensam o uso de cimentos acrílicos na fixação da prótese ao osso. A hidroxiapatita (HA) é um dos revestimentos cerâmicos cuja aplicação comercial tem crescido bastante, principalmente em cirurgias de substituição total de quadril (total hip replacement). A corrosão eletroquímica em metais comumente empregados em endopróteses e que aceitam o revestimento de hidroxiapatita (aços inox F138 grau 2, 316L grau 1 e liga Co-Cr-Mo F75)foi estudada, de forma a determinar se este tipo de revestimento influi ou não na corrosão. Através de testes, e análises metalográficas e de microscopia eletrônica de varredura, foi analisada a corrosão destes materiais em dois meios fisiológicos (Soro Bovino e Soro Fisiológico), comparando-se os resultados obtidos com e sem revestimento de hidroxiapatita. / MetaIs are widely used in implants (endoprostheses), mainly in orthopedic ones. The physiologic solution is very aggressive, and promote the metal corrosion, that may drive the patient that receive the implant to serious complications. Coatings over the base metal are being applied to improve the corrosion resistance. Recently, ceramic porous-coating began to be used. This kind of coating allows the bone tissue to ingrowth into the pores of HA-coated, and so avoid the use of acrylic cements do bind the protesis to the bone. The hidroxiapatite (HA) is one of the ceramic coatings that the commercial use have been growing, mainly in total hip replacement surgeries. The Electro-Chemical corrosion in the most common metaIs used in endoprostheses, that accept the HA-coat was studied (stainless steels F138 grade 1 and 316L grade 2 and F75 Co-Cr-Mo alloy). By this way, this study aimed to tell if the HA-coat has any influence in the corrosion rate. Trough chemical-electro corrosion tests, and metallographies, and electronic microscopy, the corrosion of these metaIs was analyzed in two different physiologic solutions, confronting the results between HA-coated and non coated samples. Coated samples had, in both solutions, a lower corrosion rate. The bovine solution was more agressive between non coated samples. But fisiologic solution was more agressive with coated samples. Between coated samples, F75 alloy had the lower corrosion rate. But F138 stainless steel without coating was the less corroded.
89

A Rapid Spectrophotometric Assay for Quantifying Seed Coat Saponins in Quinoa

Szabo, Sydney Diver 09 December 2020 (has links)
Background and objectives: The commonly used afrosimetric foam-height method for quantifying saponins in quinoa is rapid but imprecise. A rapid UV/Vis method, utilizing the Liebermann-Burchard (LB) color reaction, was compared to the foam method across a range of saponin levels in washed and unwashed seed. Findings: A 6 min UV/Vis method provided greater precision and accuracy than the afrosimetric method at the lower saponin levels found in washed quinoa. The afrosimetric method did not differentiate saponin levels below 0.6 mg/mL but allows for useful relative comparisons of saponin content in unwashed quinoa where the foam height is large. Conclusions: The UV/Vis method is superior for analyzing saponins present on washed quinoa seed, while the foam method is adequate for saponin measurements in unwashed seed. Significance and novelty: The UV/Vis assay provides a new tool that can be used for in-process quality control in large-scale processing facilities, allowing for rapid, accurate determination of completion of the desaponization step.
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Composition Effects on Sheen and Spread Rate of an Interior Flat, One Coat Latex Paint Formulation

Christensen, Dana James, II 01 August 2015 (has links)
Interior flat, white latex paint is a common coating applied to walls around the world. Development of a coating with one coat hide capability is a pinnacle achievement for paint formulators as it has the potential to save consumers both time and money. One coat paints already exist on the market, but they are limited in color, coverage, and often have many disclaimers. Work done was part of a project initiated by ChemoursTM Titanium Technologies. The goal of the project presented in this article was to create an interior flat, white latex paint that yields a spread rate of greater than 400 ft2/gal., which is advertised by many below critical pigment volume concentration (CPVC) commercial paints. In order to achieve this goal, an above CPVC paint with a high TiO2 content was created and continuously improved. Improvement of the formulation involved numerous experimental variations including adjustments to the hydroxyethylcellulose (HEC) molecular weight, dispersant chemistry, latex chemistry, TiO2 concentration, extender package, and rheology modifier type. The sheen value, relative light scattering, and spread rate were the main measurements conducted in order to judge formulation improvement. Complications with the spread rate procedure forced its adaptation in order to collect less variable data with the high density, shear thinning formulations. It was found that shorter opacity charts yielded more precise spread rate data than the longer opacity charts. An attempt at correlating rheology with sheen development resulted in the conclusion that the pigment and extender particle package is the greatest driving factor behind sheen reduction. The rheology modifier type and dispersant chemistry did not affect the flatness of the paint nearly as much. A Keyence VR-3000 series One-Shot 3D Measuring Macroscope was used to show that surface roughness does not directly correlate to the sheen value when a number of flat paints with different sheens were analyzed. This project is an ongoing effort and the information contained in this document will substantially help future development.

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