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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.
1

Kinetic studies on the supported liquid membrane extraction of organic acids

Sirman, Tuba Remziye January 1994 (has links)
No description available.
2

A study of the effect of oxygen limitation on antibiotic production and its relevance to screening for secondary metabolites

Dunstan, Gerald Hugh January 1998 (has links)
No description available.
3

Chemical and enzymatic synthesis of organosulfur compounds

Shepherd, S. D. January 2002 (has links)
No description available.
4

Condition assessment of the northern climatic research house at the USDA forest service forest products laboratory

Johnson, Tanaya 08 December 2023 (has links) (PDF)
In 2001 a Northern Climatic Test House (the House) was constructed to demonstrate appropriate and novel building techniques and materials for the upper Midwest region of the USA. The House is a 2,300-square-foot, two-story structure located on the grounds of the USDA Forest Service Forest Products Laboratory (FPL) in Madison, Wisconsin. It is considered a research structure and not part of the FPL’s building inventory. Following construction, the House was heated and cooled but not occupied. Regular (sometimes daily) tours were conducted from it’s opening until about 2008, when tours had diminished to less than one per week. Since eliminating regular tours, the house has been used occasionally for special events, intermittent tours, and storage. In May-July 2023 a visual and minimally invasive condition assessment was performed on the House. This report details the findings of this assessment. This report focuses on existing or potential problem areas.
5

A study of freeze denaturation of proteins

Chen, Ya-Huei January 2000 (has links)
No description available.
6

Developing a Bio-based Wood Composite using Refined Cottonseed Protein Adhesives.

Stratton, Julianna Nicole 03 May 2019 (has links)
A growing market of environmentally-conscious consumers combined with a progression toward ‘greener’ products has caused the wood industry to investigate adhesives containing little to no formaldehyde. This study examines cottonseed proteins’ ability to bind southern yellow pine for plywood applications. Three-ply plywood panels were constructed with varying blends of cottonseed protein isolate (CSPI), soy protein, and phenol: formaldehyde adhesive. Wet and dry shear testing revealed that while the novel adhesives did not perform as well as a commercial control, the CSPI and soy adhesives generated similar shear strengths. Another set of boards were created, varying the CSPI amount added and the ratio of water. The powdered adhesive was spread at 15, 25, 35 and 45 lbs./1000 ft2 and the ratios of protein to water (w/w) were 0.5, 1.0, 1.5 and 2. The resulting boards were tested for internal bond strength (IB) using ASTM D1037 and the treatments were found to not be statistically different. Furthering the study into optimizing the temperature and time, the lowest amount and water ratio were used. The highest mean IB strength was obtained by pressing at 284°F (140 ℃). The highest mean IB strength for time was 10 minutes and produced IB strengths significantly different from all other pressing times. Temperature and time were not found to interact and therefore each affected the mean IB strength individually (p = 0.0553). Using the optimized time and temperature CSPI adhesive, commercial cottonseed meal (CM), water washed cottonseed meal (WW) and defatted cottonseed flour (DF) were used to decide if purity of the protein mattered and if the amount had changed. Using ASTMD1037, it was discovered that WW at 45 lbs./1000 ft2 had the highest mean internal bond strength. Boards made with CSPI adhesive alone and CSPI with guayule were tested for termite resistance, first by using hardwood veneer and later softwood, against the native subterranean termite Reticulitermes spp. Both tests were completed by AWPA E1-16 standard trials. Each was found that CSPI had a performance against termites that was not significantly different from guayule (a known antifeedant). CSPI’s ability to deter termites is a place for future exploration and is not looked at in depth in this study.
7

Proposta de um modelo conceitual de biorrefinaria com estrutura descentralizada

Borges, Fernanda Cabral January 2010 (has links)
A busca por segurança energética tem feito com que a maioria dos países empenhe-se na busca por fontes alternativas de energia, procurando mitigar problemas econômicos, sociais e ambientais. Espera-se que a biomassa, disponível de forma geograficamente dispersa, venha a tornar-se um dos principais recursos renováveis na produção de alimentos, materiais, produtos químicos, combustíveis e energia. Nesse cenário, o desenvolvimento de biorrefinarias representa a chave para uma produção integrada, combinando rotas de conversões químicas, bioquímicas e termoquímicas, no processamento da biomassa, visando à utilização otimizada dos recursos disponíveis. As biorrefinarias com estruturas descentralizadas são uma alternativa à centralização de produções em grandes plantas industriais e à monocultura, pois utilizam biomassas disponíveis regionalmente, integram sistemas de produção, potencializando os recursos locais, reduzem custos com logística e impactos ambientais, além de melhorarem a distribuição da renda. O presente trabalho apresenta uma revisão da disponibilidade de biomassa no Brasil e no mundo, com especial interesse no aproveitamento de microalgas e resíduos orgânicos, dos principais produtos de interesse e conceitos de biorrefinarias existentes. O objetivo é discutir qual é o conceito que melhor se adapta às necessidades do cenário brasileiro, bem como propor um modelo com estrutura descentralizada em duas ou três etapas, visando à otimização de um processamento sustentável de biomassa para obtenção de vários produtos comerciáveis e energia, além de delinear diretrizes para investimentos na área. É apresentada uma metodologia para a tomada de decisões na concepção e análise de viabilidade do projeto conceitual de uma biorrefinaria, considerando-se também as restrições de ordem ecológica, econômica e tecnológica. Como estudo de caso, é proposta uma biorrefinaria a partir de microalgas. A escolha por microalgas como matéria-prima é baseada nas vantagens que sua utilização apresenta frente à de outras biomassas, dentre elas cita-se a capacidade de produção rápida e durante todo o ano, a captura do CO2 necessário ao seu crescimento, a necessidade de menos água do que plantas terrestres, são cultiváveis em água salobra e terras não aráveis, apresentam elevado teor de óleo, seus nutrientes podem ser obtidos a partir de águas residuais, sua composição bioquímica pode ser modulada por diferentes condições de crescimento e são capazes de produção fotobiológica de bio-hidrogênio. Das alternativas de rotas possíveis para seu processamento, são apresentadas duas que apontam como sendo as mais promissoras: o uso da microalga como substrato de algum outro microorganismo, visando à obtenção de compostos com maior valor agregado, tais como biopolímeros, e o uso do processo de pirólise rápida para obtenção de bio-óleo, que deve ser processado posteriormente, visando à especificação em biocombustível. As vantagens da otimização do cultivo, colheita, rotas viáveis de processamento e a análise do potencial econômico desse modelo, indicam uma excelente oportunidade para obtenção de um espectro de produtos de alto valor agregado e energia e um grande potencial de aplicação. / The search for energy security has been doing with that most of the countries strive to seek alternative sources of energy that allows mitigating economic, social and environmental problems. It is expected that biomass, available on a geographically dispersed way, will become one of the major renewable resources for food, materials, chemicals, fuels and energy production. Additionally, the development of biorefineries represents the key to an integrated production, combining chemical, biochemical and thermochemical conversion routes for biomass processing, aiming the optimized use of available resources. Biorefineries with decentralized structure are an alternative to the centralization of production in large industrial plants and to the monoculture because it uses biomass regionally available, integrates production systems potentiating local resources, reduces logistics costs and environmental impacts, as well as improves income distribution. This work presents a review of: i) biomass availability in Brazil and in the world, focus on the use of microalgae and organic wastes; ii) the main products of interest; and; iii) concepts of existing biorefineries. The objective is to discuss which one is the concept that better fits the needs of the Brazilian scenario and propose a new model with decentralized structure in two or three stages, seeking to an optimized and sustainable biomass processing to obtain various marketable products and energy, and delineate guidelines for investment in the area. It is presented a methodology for making the conceptions decisions and feasibility analysis of the conceptual design of a generic refinery, considering also the ecological, economic and technological constraints. As a case study, it is proposed a biorefinery from microalgae. The choice of microalgae as a raw material is based on the advantages that their use offers over the others biomasses. Among the advantages it can be cited the ability for rapid production and during all the year, the capture of CO2 for its growth, the need for less water than land plants, they can be cultivated in brackish water and non-arable land, have a high oil content, nutrients can be obtained from waste water, their biochemical composition can be modulated by different growth conditions and are capable of producing photobiology bio-hydrogen. Of the possible alternative routes for microalgae processing, are presented two as the most promising: the use of microalgae as a substrate for some other microorganism in order to obtain compounds with high added value, biopolymers as an example, and use the process of fast pyrolysis for obtaining bio-oil, which will be processed later in order to specify biofuels. The advantages of the cultivation optimization, harvesting, processing viable routes and analyzing the economic potential of this model indicate an excellent opportunity to obtain a spectrum of value-added products and energy and its great potential for application.
8

Selective break-down of flax shove for the recovery of high-value bio-products

Parsons, Robert Vaughan January 2013 (has links)
A series of investigations was undertaken regarding the biorefining of biomass for the recovery of multiple high-value products. The overall objective was to develop a simple, selective breakdown approach for flax shive, addressing three specific research areas: material properties; extraction processing; and product purification. This thesis includes five published papers and additional research all related to the topic. Flax shive represents the woody residue left over after removing fibre from flax straw. It is composed of lignified xylem tissue. Flax shive is readily available in large quantities, at low cost, and with relatively consistent particle-size and composition characteristics. Frictional behaviour investigations of bulk flax shive showed differing effects for addition of alcohols versus water. Adding any liquid significantly increased internal friction. The wall friction effects, however, depended on the liquid. Friction was increased significantly by water, but not as much by alcohols. Absorptive behaviour of flax shive, specifically liquid-holding capacity, was assessed using five liquids and compared to three other biomass materials. Flax shive was found to be a comparatively poor absorbent, a desirable behaviour for a feedstock used in aqueous- or alcohol-based processing. The first step extraction employed sodium ethoxide catalyst in anhydrous ethanol. Yield of solvent-soluble organics varied linearly with catalyst concentration. At 1.0 M the yield was 54.5 ± 14.5 mg/g dry basis (db). Analyses using 1H NMR consistently showed extracts to be phenolic in nature, and to contain no carbohydrate constituents. The second step extraction of hemicellulose polysaccharides was done using aqueous 1.0 M sodium hydroxide. The yield of carbohydrate precipitates was consistent, 99.4 ± 5.1 mg/g (db), and was unaffected by pretreatment. Analyses of polysaccharide backbone monomers showed consistently high molar ratios of xylose-to-glucose, i.e., 25.5 ± 3.4, with no mannose present. These results suggested a high concentration of glucuronoxylan polymer, likely greater than 90% by mass, with no glucomannan present. Economic evaluation showed two-stage extraction of high-value products to be a potentially viable business. Such processing also tied directly to government polices aimed at increasing value-add from agricultural materials. Overall, flax shive was found to be a desirable feedstock for recovery of high-value bio-products.
9

Selective break-down of flax shove for the recovery of high-value bio-products

Parsons, Robert Vaughan January 2013 (has links)
A series of investigations was undertaken regarding the biorefining of biomass for the recovery of multiple high-value products. The overall objective was to develop a simple, selective breakdown approach for flax shive, addressing three specific research areas: material properties; extraction processing; and product purification. This thesis includes five published papers and additional research all related to the topic. Flax shive represents the woody residue left over after removing fibre from flax straw. It is composed of lignified xylem tissue. Flax shive is readily available in large quantities, at low cost, and with relatively consistent particle-size and composition characteristics. Frictional behaviour investigations of bulk flax shive showed differing effects for addition of alcohols versus water. Adding any liquid significantly increased internal friction. The wall friction effects, however, depended on the liquid. Friction was increased significantly by water, but not as much by alcohols. Absorptive behaviour of flax shive, specifically liquid-holding capacity, was assessed using five liquids and compared to three other biomass materials. Flax shive was found to be a comparatively poor absorbent, a desirable behaviour for a feedstock used in aqueous- or alcohol-based processing. The first step extraction employed sodium ethoxide catalyst in anhydrous ethanol. Yield of solvent-soluble organics varied linearly with catalyst concentration. At 1.0 M the yield was 54.5 ± 14.5 mg/g dry basis (db). Analyses using 1H NMR consistently showed extracts to be phenolic in nature, and to contain no carbohydrate constituents. The second step extraction of hemicellulose polysaccharides was done using aqueous 1.0 M sodium hydroxide. The yield of carbohydrate precipitates was consistent, 99.4 ± 5.1 mg/g (db), and was unaffected by pretreatment. Analyses of polysaccharide backbone monomers showed consistently high molar ratios of xylose-to-glucose, i.e., 25.5 ± 3.4, with no mannose present. These results suggested a high concentration of glucuronoxylan polymer, likely greater than 90% by mass, with no glucomannan present. Economic evaluation showed two-stage extraction of high-value products to be a potentially viable business. Such processing also tied directly to government polices aimed at increasing value-add from agricultural materials. Overall, flax shive was found to be a desirable feedstock for recovery of high-value bio-products.
10

Proposta de um modelo conceitual de biorrefinaria com estrutura descentralizada

Borges, Fernanda Cabral January 2010 (has links)
A busca por segurança energética tem feito com que a maioria dos países empenhe-se na busca por fontes alternativas de energia, procurando mitigar problemas econômicos, sociais e ambientais. Espera-se que a biomassa, disponível de forma geograficamente dispersa, venha a tornar-se um dos principais recursos renováveis na produção de alimentos, materiais, produtos químicos, combustíveis e energia. Nesse cenário, o desenvolvimento de biorrefinarias representa a chave para uma produção integrada, combinando rotas de conversões químicas, bioquímicas e termoquímicas, no processamento da biomassa, visando à utilização otimizada dos recursos disponíveis. As biorrefinarias com estruturas descentralizadas são uma alternativa à centralização de produções em grandes plantas industriais e à monocultura, pois utilizam biomassas disponíveis regionalmente, integram sistemas de produção, potencializando os recursos locais, reduzem custos com logística e impactos ambientais, além de melhorarem a distribuição da renda. O presente trabalho apresenta uma revisão da disponibilidade de biomassa no Brasil e no mundo, com especial interesse no aproveitamento de microalgas e resíduos orgânicos, dos principais produtos de interesse e conceitos de biorrefinarias existentes. O objetivo é discutir qual é o conceito que melhor se adapta às necessidades do cenário brasileiro, bem como propor um modelo com estrutura descentralizada em duas ou três etapas, visando à otimização de um processamento sustentável de biomassa para obtenção de vários produtos comerciáveis e energia, além de delinear diretrizes para investimentos na área. É apresentada uma metodologia para a tomada de decisões na concepção e análise de viabilidade do projeto conceitual de uma biorrefinaria, considerando-se também as restrições de ordem ecológica, econômica e tecnológica. Como estudo de caso, é proposta uma biorrefinaria a partir de microalgas. A escolha por microalgas como matéria-prima é baseada nas vantagens que sua utilização apresenta frente à de outras biomassas, dentre elas cita-se a capacidade de produção rápida e durante todo o ano, a captura do CO2 necessário ao seu crescimento, a necessidade de menos água do que plantas terrestres, são cultiváveis em água salobra e terras não aráveis, apresentam elevado teor de óleo, seus nutrientes podem ser obtidos a partir de águas residuais, sua composição bioquímica pode ser modulada por diferentes condições de crescimento e são capazes de produção fotobiológica de bio-hidrogênio. Das alternativas de rotas possíveis para seu processamento, são apresentadas duas que apontam como sendo as mais promissoras: o uso da microalga como substrato de algum outro microorganismo, visando à obtenção de compostos com maior valor agregado, tais como biopolímeros, e o uso do processo de pirólise rápida para obtenção de bio-óleo, que deve ser processado posteriormente, visando à especificação em biocombustível. As vantagens da otimização do cultivo, colheita, rotas viáveis de processamento e a análise do potencial econômico desse modelo, indicam uma excelente oportunidade para obtenção de um espectro de produtos de alto valor agregado e energia e um grande potencial de aplicação. / The search for energy security has been doing with that most of the countries strive to seek alternative sources of energy that allows mitigating economic, social and environmental problems. It is expected that biomass, available on a geographically dispersed way, will become one of the major renewable resources for food, materials, chemicals, fuels and energy production. Additionally, the development of biorefineries represents the key to an integrated production, combining chemical, biochemical and thermochemical conversion routes for biomass processing, aiming the optimized use of available resources. Biorefineries with decentralized structure are an alternative to the centralization of production in large industrial plants and to the monoculture because it uses biomass regionally available, integrates production systems potentiating local resources, reduces logistics costs and environmental impacts, as well as improves income distribution. This work presents a review of: i) biomass availability in Brazil and in the world, focus on the use of microalgae and organic wastes; ii) the main products of interest; and; iii) concepts of existing biorefineries. The objective is to discuss which one is the concept that better fits the needs of the Brazilian scenario and propose a new model with decentralized structure in two or three stages, seeking to an optimized and sustainable biomass processing to obtain various marketable products and energy, and delineate guidelines for investment in the area. It is presented a methodology for making the conceptions decisions and feasibility analysis of the conceptual design of a generic refinery, considering also the ecological, economic and technological constraints. As a case study, it is proposed a biorefinery from microalgae. The choice of microalgae as a raw material is based on the advantages that their use offers over the others biomasses. Among the advantages it can be cited the ability for rapid production and during all the year, the capture of CO2 for its growth, the need for less water than land plants, they can be cultivated in brackish water and non-arable land, have a high oil content, nutrients can be obtained from waste water, their biochemical composition can be modulated by different growth conditions and are capable of producing photobiology bio-hydrogen. Of the possible alternative routes for microalgae processing, are presented two as the most promising: the use of microalgae as a substrate for some other microorganism in order to obtain compounds with high added value, biopolymers as an example, and use the process of fast pyrolysis for obtaining bio-oil, which will be processed later in order to specify biofuels. The advantages of the cultivation optimization, harvesting, processing viable routes and analyzing the economic potential of this model indicate an excellent opportunity to obtain a spectrum of value-added products and energy and its great potential for application.

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