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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

Living polymerization of novel hydrophilic polymers /

Plummer, Ronda. January 2005 (has links) (PDF)
Thesis (Ph.D.) - University of Queensland, 2006. / Includes bibliography.
82

Reactivity and mechanisms in aqueous organometallic chemistry : C-H bond activation in water catalyzed by molybdocenes /

Balzarek, Christoph, January 2000 (has links)
Thesis (Ph. D.)--University of Oregon, 2000. / Includes vita and abstract. Includes bibliographical references (p. 149-167). Also available for download via the World Wide Web; free to University of Oregon users.
83

Reactivity and mechanisms in aqueous organometallic chemistry: C-H bond activation in water catalyzed by molybdocenes

Balzarek, Christoph, 1972- January 2000 (has links)
Adviser: Kenneth M. Doxsee. xvii, 167 p. / A print copy of this title is available through the UO Libraries under the call number: SCIENCE QD412.M7 B35 2000 / The chemistry of three organometallic systems in water was studied with the goal of understanding more fully the reactivity of organometallic complexes in aqueous environments. Molybdocene complexes were found to catalyze C-H bond activation reactions in water. The catalytically active solutions were prepared from the molybdocene dimer [Cp
84

Avaliação dos atributos de qualidade de presunto cozido "cook-in" adicionado de fibra solúvel, do tipo frutooligossacarídeo de cadeia curta (ScFOS) / Evaluation of quality attributes of "cook-in" cooked ham added soluble fibers, of short-chain fructooligosaccharides (ScFOS)

Abreu, Larissa Weissheimer de, 1981- 12 January 2011 (has links)
Orientadores: Pedro Eduardo de Felício, Expedito Facco Silveira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-19T05:51:04Z (GMT). No. of bitstreams: 1 Abreu_LarissaWeissheimerde_M.pdf: 3531090 bytes, checksum: 653a23f59bd2bc7c449fe6c68f12bea6 (MD5) Previous issue date: 2011 / Resumo: O presente trabalho de pesquisa consistiu na avaliação dos efeitos da adição de fibra solúvel, do tipo frutooligossacarídeo de cadeia curta, sobre os atributos de qualidade, física, físico-químicas microbiológicas e sensoriais de presunto cozido cook-in. Os presuntos cozidos foram processados no frigorífico Marba, em São Bernardo do Campo ¿ São Paulo. Elaborou-se uma formulação padrão de presunto cozido (¿cook in¿) para 170% de rendimento sobre o peso da matéria prima, e a partir desta balancearam-se as formulações adicionadas de fibra solúvel, do tipo frutooligossacarídeo de cadeia curta (ScFOS) marca NutraFlora®. Realizaram-se quatro tratamentos, F0 ¿ padrão ou controle sem adição de fibra, F3 ¿ adição de 3% de fibra solúvel, F6 ¿ adição de 6% de fibra solúvel, F9 ¿ adição de 9% de fibra solúvel. Os produtos assim obtidos foram avaliados (em cinco pontos - aos 7, 20, 41, 62 e 93 dias) ao longo da estocagem refrigerada a 2±2ºC, quanto ao valor de pH, atividade de água (Aa), composição centesimal, teores de nitrito e nitrato, cor, força de cisalhamento, fatiabilidade, qualidade microbiológica e parâmetros sensoriais através de uma equipe treinada. Aos 45 dias de estocagem refrigerada, realizou-se um teste laboratorial de ordenação por preferência com consumidores, avaliando-se os atributos de cor, odor, sabor e firmeza (textura). Os resultados das determinações físicas, físico-químicas e sensoriais foram submetidos à análise de variância (ANOVA) para se avaliar o efeito dos tratamentos e tempo de estocagem, sendo a diferença entre as médias determinada pelo teste de Tukey com um intervalo de confiança de 95%. Para a avaliação sensorial de ordenação por preferência de consumidores foram utilizados os testes de Friedman e de Fisher. Os produtos apresentaram uma tendência no incremento dos valores de pH em função do tempo de estocagem. O aumento do teor de fibra solúvel adicionado resultou uma redução significativa (p<0,05) na atividade de água dos produtos. Para os parâmetros de cor avaliados, observou-se que a adição de níveis crescentes de fibra solúvel promoveu a diminuição dos valores de luminosidade (L*) e aumento no teor de vermelho (a*). Os maiores valores do teor de amarelo (b*) ao longo do período de estocagem foram observados no tratamento F0 ¿ sem adição de fibras. Os tratamentos F0 e F9 apresentaram nos primeiros 40 dias de estocagem, uma queda acentuada nos valores obtidos dos parâmetros C* (Chroma) e h (hue), enquanto os tratamentos F3 e F6 demonstraram a tendência de estabilidade ao longo da estocagem. Os resultados das avaliações microbiológicas indicaram que a adição de fibra solúvel não afetou a estabilidade microbiológica dos presuntos cozidos, uma vez que as contagens de micro-organismos deteriorantes e patogênicos mantiveram-se dentro dos limites estabelecidos pela legislação vigente ao longo do período de estocagem. A avaliação sensorial com equipe treinada evidenciou para os tratamentos contendo fibra solúvel, maior intensidade da cor rósea característica tanto na superfície das peças inteiras como nas fatias do produto. Por outro lado, para os atributos descoloração, exsudação, coesividade, sabor e odor, a equipe treinada não reportou influência da adição da fibra solúvel. A avaliação realizada com consumidores revelou preferência pelos tratamentos F3 e F6 para todos os atributos avaliados, entretanto o tratamento F9 foi o menos preferido em relação ao sabor e firmeza, evidenciando que a adição até o nível de 6% de fibra solúvel melhora a aceitação das características sensoriais avaliadas neste estudo do presunto cozido / Abstract: The present research aims the evaluation of the effects of addition of soluble fiber of short chain fructooligosaccharides (ScFOS - NutraFlora ®) over the physical, physical-chemical, microbiological and sensorial quality attributes of cook-in cooked ham. The processing of cooked hams was conducted at Marba industry, Sao Bernardo do Campo - São Paulo, Brazil. There was elaborated a standard formula of cook-in cooked ham, for 170% yield over weight of raw material, from which were balanced other formulas with soluble fiber addition:F0, F3, F6 e F9; standard (without fiber addition, 3%, 6% and 9% of fiber addition, respectively). The hams were evaluated through refrigerated storage at 2 ± 2 º C at five points (7, 20, 41, 62 and 93 days) for pH, water activity (Aw) values, centesimal composition, contents of nitrite and nitrate, colour, shear force, sliceability measurement, microbiological and sensory parameters using a trained judges. At the 45th day of storage there was processed a ranking preference test with regular consumers, assessing colour, characteristic odor, characteristic taste and firmness (texture) attributes. Physical measurements, physical-chemical and sensory results were analyzed for variance (ANOVA) to survey soluble fiber addition effects over considered parameters. The difference between means was ascertained through Tukey test at 95 % of confidence. For the ranking test there were used Friedman and Fisher tests. The hams exhibited a tendency of increasing pH values according to storage. The increasing content of soluble fiber (NutraFlora ®) added resulted in a significant reduction (p <0.05) water activity of products. For colour parameters, the rising of soluble fiber resulted in reduction of luminosity (L*) and addition of redness (a*) values. The highest yellowness (b*) values during the storage were observed at F0 treatment - without the fiber addition. The treatments F0 and F9 had at the first 40 days of storage, a sharp drop for C * (chroma) and h (hue) values while F3 and F6 treatments remained stable during that period. Microbiological evaluations pointed that the addition of soluble fiber did not affected the microbiological stability of cooked hams as the spoilage and pathogenic microorganisms counts remained within Brazilian official limits throughout the storage period. Sensory evaluation with trained judges pointed that the characteristic pink colour of whole ham and slices had higher intensity in the samples with soluble fiber addition. On the other hand, attributes of discoloration, exudation, cohesiveness, taste and odor, had no influence over the different treatments. The assessment carried out with consumers submitted comments similar to those obtained with the trained judges. The ranking preference test revealed higher preference for F3 and F6 for all the considered traits, meanwhile F9 was the least preferred regarding characteristic taste and firmness, pointed that the addition as high as 6% of soluble fiber NutraFlora ® increase the cooked ham acceptance / Mestrado / Tecnologia de Alimentos / Mestre em Tecnologia de Alimentos
85

Effects of diets differing in rumen soluble nitrogen on poor quality roughage utilization by sheep

Jooste, Anna Margarietha 08 November 2012 (has links)
The aim of this study was to determine whether a rapid release N source can be substituted with a slow release N source without having any negative effects on intake, digestibility, rumen fermentation and microbial protein synthesis, if sheep are fed a poor quality roughage. Five rumen cannulated wethers were used in the trial in a 5x5 latin square design. Cannulated wethers were assigned to different treatments after each experimental period. The treatments studied had different proportions of urea to OptigenrII, with the same inclusion level of starch and a mineral premix between treatments. The five different treatments were: 100% urea; 75% urea:25% OptigenrII; 50% urea:50% OptigenrII; 25% urea:75% OptigenrII and 100% OptigenrII. Significant differences (P<0.05) between the 25% urea:75% OptigenrII and the other treatments in terms of intake suggested that a combination of urea and OptigenrII might be the preferred supplementation due to a significantly higher dry matter intake (DMI), organic matter intake (OMI), neutral detergent fibre intake (NDF intake) and digestible organic matter intake (DOMI). The intake variables of 100% urea and 100% OptigenrII did not differ (p>0.05). No differences (P>0.05) were recorded for dry matter digestibility (DMD), organic matter digestibility (OMD) and neutral detergent fibre (NDF) digestibility between treatments. However, the 100% OptigenrII treatment had a significant (P<0.05) lower apparent nitrogen digestibility, which might be the result of a slower rumen NH3-N release and higher nitrogen excretion than the other treatments. No differences were observed for pH and VFA between different treatments. The rumen NH3-N concentration of the 100% OptigenrII treatment was significantly (P<0.05) lower than the 100% urea treatment at 2 and 4 hours after infusion. The effective degradability of both DM and NDF did not differ (P>0.05) between treatments. Neither were there differences between treatments for total microbial crude nitrogen (MCN) production. Based on biological evaluation, it could be suggested that urea might be substituted with OptigenrII in supplements. From an economical point of view, urea might still be the preferred NPN source, as urea is cheaper than OptigenrII in terms of R/kg nitrogen. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted
86

Characterizing Immune-modulatory Components of Human Milk: The Fate and Function of Soluble CD14 and the Human Milk Metagenome

Ward, Tonya L. January 2014 (has links)
Background During the first stages of development human infants are either fed human milk or human milk substitutes (infant formulas). The composition of infant formulas and human milk differ drastically, including a difference in protein constituents and bacterial load. Due to the high global frequency of infant formula use, the humanization of infant formulas to better reflect the complex nature of human milk is warranted. To better understand the role of human milk components, the fate and function of a key bacterial sensor in human milk, soluble CD14, was determined. Additionally, the microbiome of human milk was analyzed from a metagenomic standpoint in an attempt to determine which types of bacteria are present in human milk and what their potential biological function might be. Results In rodent models, ingested sCD14 persisted in the gastrointestinal tract and was transferred intact into the blood stream. Once transferred to the blood, ingested sCD14 retained its ability to recognize lipopolysaccharide and initiate an immune response in pups. This transfer of sCD14 across the epithelial barrier was also observed in human cells in vitro, where it appears to be dependent on Toll-like receptor 4. Using Illumina sequencing and the MG-RAST pipeline, the human milk metagenome of ten mothers was sequenced. DNA from human milk aligned to over 360 prokaryotic genera, and contained 30,128 open reading frames assigned to various functional categories. The DNA from human milk was also found to harbor immune-modulatory DNA motifs that may play a significant role in immune development of the infant. Conclusions Given the complex nature of human milk in comparison to its bovine or plant based substitutes, the results presented in this thesis warrant future modification of infant formulas to include non-nutritive bioactive components. Current human milk components not yet present in infant formulas include the diverse microbiome of human milk, the immune-modulatory DNAs which those microbes harbor, and bioactive human proteins such as sCD14.
87

Efekt solubilního endoglinu na endotelové buňky in vitro / Effect of soluble endoglin to endothelial cells in vitro

Klingová, Rebeka January 2017 (has links)
Charles Univerzity in Prague Faculty of Pharmacy in Hradec Králové Department of Biological and Medical Sciences Candidate: Rebeka Klingová Supervisor: PharmDr. Petra Fikrová, Ph.D. Title of diploma thesis: Effect of soluble endoglin to endothelial cells in vitro Aim: We determined the effects of soluble endoglin on endothelial cells, by the means of inflammatory markers. The aim of the study was to point out the possible association of the soluble endoglin with endothelial dysfunction. Methods: For our study we have selected the human endothelial cells from umbilical vein - HUVEC. We have influenced the cells with soluble endoglin in two concentrations and at two different time intervals. The results were evaluated in the statistical program, in which we have compared the control group with influenced cells and two concentrations between each other. The expressions of inflammatory markers were analyzed on the level of mRNA, using the real-time PCR method. Results: Significant changes in the expression of markers were observed on the vascular and intracellular adhesion molecule at both concentrations compared to the control group. Increased values of transcription were available also for cyclooxygenase 2 and decreased values for cadherin 5 compared to the control group. Conclusion: Changes in...
88

Supramolecular Solar Cells

Subbaiyan, Navaneetha Krishnan 08 1900 (has links)
Supramolecular chemistry - chemistry of non-covalent bonds including different type of intermolecular interactions viz., ion-pairing, ion-dipole, dipole-dipole, hydrogen bonding, cation-p and Van der Waals forces. Applications based on supramolecular concepts for developing catalysts, molecular wires, rectifiers, photochemical sensors have been evolved during recent years. Mimicking natural photosynthesis to build energy harvesting devices has become important for generating energy and solar fuels that could be stored for future use. In this dissertation, supramolecular chemistry is being explored for creating light energy harvesting devices. Photosensitization of semiconductor metal oxide nanoparticles, such as titanium dioxide (TiO2) and tin oxide (SnO2,), via host-guest binding approach has been explored. In the first part, self-assembly of different porphyrin macrocyclic compounds on TiO2 layer using axial coordination approach is explored. Supramolecular dye sensitized solar cells built based on this approach exhibited Incident Photon Conversion Efficiency (IPCE) of 36% for a porphyrin-ferrocene dyad. In the second part, surface modification of SnO2 with water soluble porphyrins and phthalocyanine resulted in successful self-assembly of dimers on SnO2 surface. IPCE more than 50% from 400 - 700 nm is achieved for the supramolecular self-assembled heterodimer photocells is achieved. In summary, the axial ligation and ion-pairing method used as supramolecular tools to build photocells, exhibited highest quantum efficiency of light energy conversion with panchromatic spectral coverage. The reported findings could be applied to create interacting molecular systems for next generation of efficient solar energy harvesting devices.
89

An Adhesive Vinyl-acrylic Electrolyte And Electrode Binder For Lithium Batteries

Tran, Binh 01 January 2013 (has links)
This dissertation describes a new vinyl-acrylic copolymer that displays great potential for applications in lithium ion batteries by enabling processes that are novel, faster, safer, and less costly than existing manufacturing methods. Overall, the works presented are based on tailored chemical synthesis directly applied to lithium ion battery manufacturing. Current manufacturing methods still have many flaws such as toxic processes and other time consuming if not costly steps. Understanding the chemistry of materials and processes related to battery manufacturing allows the design of techniques and methods that can ultimately improve the performance of existing batteries while reducing the cost. Chapter 1 provides an introduction to lithium batteries in terms of energy output, standard electrode and electrolyte materials, and processes for fabricating battery components. In this chapter, slightly more emphasis is placed on the electrolyte aspects of lithium battery technology, namely the plasticization of gel polymer hosts by liquid electrolyte and the standalone solid polymer electrolytes. Chapter 2 focuses on the free radical polymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMA), methyl methacrylate (MMA), and isobutyl vinyl ether (IBVE) monomers to afford a vinyl-acrylic poly(PEGMA-co-MMA-co-IBVE) random copolymer and its detailed properties as a soluble, amorphous, and adhesive electrolyte that is able to permanently hold 800 times its own weight. Such material properties envision a printable battery manufacturing procedure, since existing electrolytes lack adhesion at a single macromolecular level. Without adhesion, the cathode and anode layers easily delaminate from the cell assembly, not to mention weak interfacial contact and poor mass transfer with the electrolyte. Many soft matter type electrolytes have been reported, but they lack either adhesive strength or ease of solubility. Obtaining both properties in iv a single material is a rarity. Chapter 3 aims at improving the ionic conductivity of the poly(PEGMA-co-MMA-co-IBVE) copolymer electrolyte by studying the effect of internal and external plasticizers, molecular weight of PEGMA monomer, and addition of inorganic solid state electrolytes. The inorganic electrolyte additives include Li(1+x+y)AlxTi(2-x)SiyP(3-y)O12, LiILi2WO4 mixture, Li7La3Zr2O12, and Li2S-P2S5 as part of an organic-inorganic hybrid approach. Electrolytes can also be used as an electrode binder so long as it has structural integrity and allows ion transfer to and from the active electrode material during insertion/extraction processes. In Chapter 4, the use of this electrolyte as a water-soluble binder for the aqueous fabrication of LiCoO2 cathodes is presented. Results of this study demonstrated the first aqueous process fabrication of thick, flexible, and fully compressed lithium ion battery electrodes by using commercial nickel foam as a supporting current collector. This feat is rather impressive because these properties are far superior to other aqueous binders in terms of material loading per electrode, specific area capacity, durability, and cell resistance. Finally, Chapter 5 expands on this concept by using the poly(PEGMA-co-MMA-co-IBVE) copolymer for the aqueous fabrication of a low voltage Li4Ti5O12 anode type electrode. Each component of a lithium ion battery serves a distinct role and undergoes unique electrochemical processes during cycling. The fact that this poly(PEGMA-co-MMA-co-IBVE) copolymer can be used in all three components, albeit for only about 50 cycles in a liquid half cell setup, demonstrates as a proof of concept that switching the current toxic manufacturing of lithium-ion batteries to an aqueous process is highly feasible. Furthermore, new electrode manufacturing techniques are also deemed possible. A conclusive summary along with directions for future work concerning the v novelties of this unique multifunctional vinyl-acrylic copolymer as an electrolyte, a cathode binder, and an anode binder are discussed in Chapter 6.
90

Understanding metal concentration and speciation in motorway runoff

Zakharova, J., Pouran, H., Bridgeman, John, Wheatley, A., Arif, M. 10 January 2021 (has links)
Yes / Although highway runoff has historically been extensively studied, the increasing complexity of stormwater management means that there are still significant gaps regarding the reduction of soluble metals. The work reported in this paper addresses these challenges by analysing the presence and behaviour of iron, copper and zinc in runoff from junction 24 of the M1 motorway in the UK (peak traffic flow: 30,000 vehicles per hour) and comparing it with other urban sources of metals found in the same catchment (a local brook and sewage treatment works). The sampling site included an interceptor and a treatment lagoon and the event monitoring indicated a trend by which the metals did not change their concentration or particulate soluble proportion immediately, hence showing that pre- and post-storm conditions are important factors when analysing the solubility of metals and their behaviour. The data provided further evidence of the important influence of storm characteristics on metal concentrations in highway runoff, in particular the effects of an antecedent dry weather period (ADWP). In addition, this study also helped us to better understand how the release of sodium the application of de-icer for road maintenance in winter affects the availability of zinc.

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