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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

The immobilization of Cs in cement based matrices

McCulloch, Caroline E. January 1985 (has links)
Ordinary Portland Cement (OPC) is a material of complex chemical and phase composition. Therefore its sorption characteristics were determined by examining the properties of its individual phases, as well as bulk OPC. The principal constituents of OPC along with its hydration products were tested for their potential to sorb Cs using radiocaesium tracer studies. Results showed that OPC had no significant sorption potential for Cs. It was therefore suggested that the cement composition required to be tailored by including materials which were likely to sorb Cs and moreover, improve the physical properties of the cement matrix. Two categories of materials were chosen for study:- (i) those which are normally permitted in civil engineering practice, including amorphous silica, pulverised fuel ashes (PFA) , natural pozzolari and blast furnace slag (BFS); (ii) those which were known or suspected to be good Cs sorbers but whose stability in cement were as yet unknown. These included hydrous titanium dioxide, calcined kaolin, acid zirconium phosphate, tobermorite and xonotlite. Amorphous silica, several PFA's, natural pozzolan and BFS were all examined for their sorption potential. All the materials showed, to a greater or lesser degree, a potential for immobilising Cs. The amorphous silica showed the greatest uptake of Cs and was chosen for further study. The sorption of Cs by amorphous silica was determined over a- wide range of Cs concentrations. daData were treated by the Freundlich isotherm and indicated that different sorptive mechanisms may be operating at different concentration aranges. The effect of water: solid ratio and initial pH were examined. Results showed that pH had 2 opposite effects on the silica:- (a) the high pH (-12.5) increases its sorption efficiency for Cs, compared to neutral conditions, presumably due to an enhanced negative charge on the silica surface; (b) the presence of Ca(0H)2, which was used to adjust the pH arid would be present in hydrated OPC, decreases the available silica content due to pozzolanic reactions consuming silica to form Calcium Silicate Hydrate gels (C-S-H). Hence if a silica containing material was added to cement and was the only sorbing material present, it might have to be proportioned carefully to maintain a permanent excess of silica. Leach tests were carried out on mixes of cement with amorphous silica, PFA and BFS. All gave significant improvements in leach characteristics compared to OPC alone. The effects-of curing, conditions were studied. Results showed that increasing the curing time from 28 days to 84- days or 168 days or increasing the curing temperature from 20 G to 4-0 C or both improved the leach resistance. Mercury intrusion porosimetry gave little indication that this was totally due to physical encapsulation and studies of the pore fluids on the samples showed beyond doubt that a strong chemical mechanism was involved. It was hypothesised that C-S-H with a high silica content was responsible for the chemical retention of Cs. In OPC the C-S-H has a C/S ratio of -1.7 but when amorphous silica or PFA is added this ratio is reduced and can be as low as 0.8. BFS hydrates independently from OPC but it also produces a C-S-H with a low C/S value. This hypothesis was confirmed by studies on synthetic C-S-H with a range of C/S ratios and by analysing OPC/PFA and OPC/silica pastes in the analytical electron microscope. Sorption experiments were also carried out on the second category of materials. All showed good sorption potential for Cs in neutral solutions. Sorption remained significant in the presence of Na and K as competitive species. However, the effect of Ca (OH)2, differed. Tobermorite and Xonotlite appeared to show the most significant sorption of Cs in the presence of Ca(OH,)2 while the others either reacted with Ca(OH)z or discharged Cs - presumably by exchange for Ca. Tobermorite and Xonotlite were further studied. Desorption experiments and the effect of varying the Cs concentration as well as pH effects were investigated. Both materials gave straight line plots on a Freundlich isotherm indicating that one sorptive mechanism operated over a wide concentration range. Sorption increased with pH but unfortunately desorption studies showed that the Cs was easily removed. Leach studies were carried out on composites with OPC containing 5-10% tobermorite. Such additions decreased the leach rate of Cs compared to OPC.
2

Chemical composition, storage stability and effect of cold-pressed flaxseed oil cake inclusion on bread quality

Ogunronbi, O, Jooste, PJ, Abu, JO, van der Merwe, B January 2010 (has links)
Abstract Flaxseed oil cake from a South African factory was screened for proximate composition, mineral content, fatty acid profile and storage stability. The oil cake was included at 10 and 15% levels (w/w) in brown bread and evaluated using a 96-member consumer panel. The oil cake contained between 38.0 and 47.3% protein, 12.8 and 26.1% crude fat and 3.7 and 5.1% ash. The total carbohydrates were mostly dietary fiber. Calcium, magnesium, phosphorus and potassium were in the range of 3.3 to 3.8, 4.8 to 5.9, 6.4 to 8.2 and 9.0 to 10.1 (mg/g), respectively. The oil from the flaxseed oil cake contained 58.5 to 59.7% of C18 omega-3 fatty acids. Peroxide levels of the flaxseed oil cake were below the threshold limits after 6 months storage. Thiobarbituric acid threshold values were exceeded after 5 months aerobic storage at 20C. Bread samples with inclusion levels of 10 and 15% flaxseed oil cake were acceptable to the consumer sensory panel.
3

Flavor chemistry of roasted filberts (Corylus avellana)

Sheldon, Ross Mark 14 August 1969 (has links)
Graduation date: 1970
4

Produção e valor nutricional de híbridos de amoreira (Morus alba L.) colhidos em diferentes idades de crescimento

Gomes, Rafael Aparecido [UNESP] 24 February 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:27:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-24Bitstream added on 2014-06-13T20:36:05Z : No. of bitstreams: 1 gomes_ra_me_jabo.pdf: 463923 bytes, checksum: 093c31f69538b0fc07e18d34599830eb (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Objetivou-se com este estudo avaliar aspectos produtivos e nutricionais dos híbridos de amoreira FM Shima-Miura (SM) e IZ 56/4 (IZ), colhidas aos 30, 60, 90 e 120 dias de crescimento. Ao atingirem a idade de crescimento pré-estabelecida, as plantas foram colhidas, sendo folhas e caules pesados e amostrados separadamente. Foram realizadas análises de fracionamento, seguindo o esquema proposto pelo CNCPS, onde carboidratos foram separados em fração A, B1, B2 e C e os compostos nitrogenados nas frações A, B1+B2, B3 e C. Para estudo da cinética de degradação ruminal utilizou-se a técnica de produção de gases in vitro, sendo os dados obtidos ajustados ao modelo logaritmo bicompartimental. O híbrido SM apresentou produção de matéria seca (MS) e proteína bruta (PB) de folhas e caules superiores à IZ (P<0.05). Nas folhas, o híbrido IZ apresentou maiores proporções de componentes relacionados à parede celular, comparando-se com o SM (P<0.05). Não houve, no entanto, diferença entre híbridos na digestibilidade in vitro da matéria orgânica (DivMO) e nos parâmetros de produção de gases (P>0,05). Com o avanço da idade de crescimento, as folhas apresentaram aumento das frações B2 (de 108 a 146 g/kg de MS) e C (de 90 a 108 g/kg de MS) dos carboidratos (P<0,05), e redução nos de PB (de 224 a 191 g/kg de MS) para as idades de crescimento entre 30 e 120 dias. Contudo não houve alteração nos teores das frações A e B1 dos carboidratos, B1+B2, B3 e C dos compostos nitrogenados, na DivMO nem na produção de gases (P>0,05). Pelo desempenho produtivo superior, recomenda-se o híbrido SM para uso em sistemas de produção de ruminantes / The objective of this study was to evaluate the production and the nutritional aspects of mulberry hybrids FM Shima-Miura (SM) and IZ 56/4 (IZ), harvested at 30, 60, 90 and 120 days of regrowth. The plants were harvested, and leaves and stems were weighed separately. Carbohydrates and protein analyses followed the scheme proposed by CNCPS. Carbohydrates were separated into fractions A, B1, B2 and C and the nitrogen compounds, in the fractions A, B1+B2, B3 and C. To study the kinetics of ruminal degradation, we used the technique of in vitro gas production, and the data fit to the model log bicompartmental. The dry matter (DM) and crude protein (CP) contents of leaves and stems from SM hybrid were greater (P <0.05) than from IZ hybrid. The IZ hybrid had greater proportions of leaf components related to the cell wall compared to SM (P <0.05). However, there were no differences between hybrids in the in vitro digestibility of organic matter (ivOMD) and in the parameters of gas production (P> 0.05). With advancing age of regrowth, the leaves showed an increase of B2 (108- 146 g /kg of DM) and C (90 to 108 g / kg DM) carbohydrate fractions (P <0.05), and decrease in CP (224-191 g / kg DM) harvested between 30 to 120 days. However, there were no changes in the contents of carbohydrate fractions A and B1, nitrogen fractions B1+B2, B3 and C, ivOMD and parameters of gas production (P> 0.05). Due to its higher production, SM hybrid is recommended to use in ruminant production systems
5

Construction of dinuclear complexes using multidentate ligands

Sampson, Claire Louise January 2000 (has links)
No description available.
6

The distribution of the constituents across the wall of unbleached spruce sulfite fibers

Kallmes, Otto 01 January 1959 (has links)
see pdf
7

Produção e valor nutricional de híbridos de amoreira (Morus alba L.) colhidos em diferentes idades de crescimento /

Gomes, Rafael Aparecido. January 2012 (has links)
Orientador: Kleber Tomás de Resende / Coorientador: Márcia Helena Machado da Rocha Fernandes / Banca: Ricardo Andrade Reis / Banca: Manoel Eduardo Rozalino Santos / Resumo: Objetivou-se com este estudo avaliar aspectos produtivos e nutricionais dos híbridos de amoreira FM Shima-Miura (SM) e IZ 56/4 (IZ), colhidas aos 30, 60, 90 e 120 dias de crescimento. Ao atingirem a idade de crescimento pré-estabelecida, as plantas foram colhidas, sendo folhas e caules pesados e amostrados separadamente. Foram realizadas análises de fracionamento, seguindo o esquema proposto pelo CNCPS, onde carboidratos foram separados em fração A, B1, B2 e C e os compostos nitrogenados nas frações A, B1+B2, B3 e C. Para estudo da cinética de degradação ruminal utilizou-se a técnica de produção de gases in vitro, sendo os dados obtidos ajustados ao modelo logaritmo bicompartimental. O híbrido SM apresentou produção de matéria seca (MS) e proteína bruta (PB) de folhas e caules superiores à IZ (P<0.05). Nas folhas, o híbrido IZ apresentou maiores proporções de componentes relacionados à parede celular, comparando-se com o SM (P<0.05). Não houve, no entanto, diferença entre híbridos na digestibilidade in vitro da matéria orgânica (DivMO) e nos parâmetros de produção de gases (P>0,05). Com o avanço da idade de crescimento, as folhas apresentaram aumento das frações B2 (de 108 a 146 g/kg de MS) e C (de 90 a 108 g/kg de MS) dos carboidratos (P<0,05), e redução nos de PB (de 224 a 191 g/kg de MS) para as idades de crescimento entre 30 e 120 dias. Contudo não houve alteração nos teores das frações A e B1 dos carboidratos, B1+B2, B3 e C dos compostos nitrogenados, na DivMO nem na produção de gases (P>0,05). Pelo desempenho produtivo superior, recomenda-se o híbrido SM para uso em sistemas de produção de ruminantes / Abstract: The objective of this study was to evaluate the production and the nutritional aspects of mulberry hybrids FM Shima-Miura (SM) and IZ 56/4 (IZ), harvested at 30, 60, 90 and 120 days of regrowth. The plants were harvested, and leaves and stems were weighed separately. Carbohydrates and protein analyses followed the scheme proposed by CNCPS. Carbohydrates were separated into fractions A, B1, B2 and C and the nitrogen compounds, in the fractions A, B1+B2, B3 and C. To study the kinetics of ruminal degradation, we used the technique of in vitro gas production, and the data fit to the model log bicompartmental. The dry matter (DM) and crude protein (CP) contents of leaves and stems from SM hybrid were greater (P <0.05) than from IZ hybrid. The IZ hybrid had greater proportions of leaf components related to the cell wall compared to SM (P <0.05). However, there were no differences between hybrids in the in vitro digestibility of organic matter (ivOMD) and in the parameters of gas production (P> 0.05). With advancing age of regrowth, the leaves showed an increase of B2 (108- 146 g /kg of DM) and C (90 to 108 g / kg DM) carbohydrate fractions (P <0.05), and decrease in CP (224-191 g / kg DM) harvested between 30 to 120 days. However, there were no changes in the contents of carbohydrate fractions A and B1, nitrogen fractions B1+B2, B3 and C, ivOMD and parameters of gas production (P> 0.05). Due to its higher production, SM hybrid is recommended to use in ruminant production systems / Mestre
8

The use of in vitro assays to screen for endocrine modulation.

Hendricks, Rahzia. January 2008 (has links)
<p>&nbsp / </p> <p align="left"><font face="Times New Roman">Aspalathus linearis (A. linearis), </font><font face="Times New Roman">commonly known as Rooibos tea or Red bush tea and </font><i><font face="Times New Roman">amellia sinensis (C. sinensis) </font></i><font face="Times New Roman">or Black tea are beverages that are consumed throughout the</font><font face="Times New Roman">world. These teas possess antioxidant, immunomodulating and anti-cancer actions. The aim</font> <font face="Times New Roman">of this study was to use <i>in vitro </i>assays to screen Rooibos and Black tea for endocrine</font> <font face="Times New Roman">modulation. </font><font face="Times New Roman">The immune modulating effects of Rooibos and Black tea were investigated using an <i>in vitro</i></font> <font face="Times New Roman">whole blood culture (WBC) assay. Unstimulated WBCs treated with Rooibos tea secreted</font> <font face="Times New Roman">higher levels of IL-6, IL-10 and IFN<font lang="JA">&gamma / </font>than cultures treated with DMSO control. Rooibos treatment of stimulated WBCs resulted in higher IL-6, lower IL-10 and no effect on IFN&gamma / </font><font face="Times New Roman">secretion compared to DMSO treated stimulated WBC. Black tea treatment of stimulated</font> <font face="Times New Roman">WBC resulted in decreased IL-6, IL-10 and IFN<font lang="JA">&gamma / </font>secretion compared to the DMSO treated</font> <font face="Times New Roman">stimulated WBC. </font><font face="Times New Roman">Extracts of Rooibos and Black tea were assessed for phytoestrogens using quantitative </font><font face="Times New Roman">estrogen ELISAs. Both teas contain phytoestrogens. The quantitative ELISAs showed that </font><font face="Times New Roman">Rooibos tea contained significantly lower estrone (E1), estradiol (E2) and estriol (E3) levels </font><font face="Times New Roman">than Black tea. The effects of Rooibos and Black tea on proliferation of the estrogen</font> <font face="Times New Roman">dependant MCF-7 cell line was determined to further characterise the phytoestrogenic</font> <font face="Times New Roman">properties of the teas. Both Rooibos and Black tea extracts caused a significant inhibition of</font> <font face="Times New Roman">MCF-7 proliferation. </font><font face="Times New Roman">This study shows that Rooibos tea and Black tea are beverages that can either stimulate or </font><font face="Times New Roman">suppress the immune system. Also, both teas contain significant levels of phytoestrogens as </font><font face="Times New Roman">determined by quantitative ELISAs. The current study confirms previous reports showing </font><font face="Times New Roman">inhibition of growth in breast cancer cell lines by phytoestrogens. The findings extend </font><font face="Times New Roman">related observations on the anti-carcinogenic potential of the two teas.</font></p>
9

Characterization and interaction of sugarcane industry residues with soil, kaolinite and Fe-oxides

Batista Benke, Monica 01 January 1998 (has links)
The sugarcane industry in Brazil produce large amounts of organic wastes including vinasse and filter cake which have been applied to agricultural soil in appreciable amounts over the past two decades. This study examines the chemical characteristics of vinasse and filter cake and their interaction with soil particles. The total concentration of heavy metals found in these residues were relatively small and considered environmentally safe for land application. About 22-100% of the total concentration of Cu, Fe, Mn, Ni, Pb and Zn in vinasse are in water soluble forms compared to only 0.3-17% in filter cake. Elevated amounts of sulfate, chloride and dissolved organic carbon (DOC) were found in the <0.22-[mu]m fraction of vinasse. Filter cake samples had high amounts of phosphate and neutral pH. Most of the 13C NMR spectra of the DOC fraction of vinasse comprised of O-alkyl and carboxyl carbons. The presence of carbohydrates and COOH/COO- was suggested by the FTIR as well. Both 13C NMR and FTIR spectra of this fraction were generally similar to the spectra of the FA fraction of soil and sewage sludge. In the POC fraction, O-alkyl and alkyl carbon were the major contributors to the 13C NMR spectra. The total nitrogen content in this fraction ranged from 21-58 g kg-1 and was about three to seven times as much as in the DOC fraction. Adsorption isotherms of DOC from vinasse on different horizons of an Ultisol indicated that DOC adsorption increased with depth. Adsorption isotherms of DOC on pure kaolinite, synthetic goethite and hematite showed that the maximum adsorption capacity of the Fe-oxyhydroxides was as much as about five times the maximum adsorption capacity of kaolinite. Concentrations of Cu, Mn, and Zn in 4M HNO3 and AAAc-EDTA extracts were higher in the "sacrificed areas" compared to the other sites. Levels of Pb were unchanged. Enrichment of most of these metals was evident up to the maximum depth of 60 cm. Sugarcane cultivation tended to reduce total carbon at the 0-20 cm depth while application of vinasse did not influence the organic matter content of these soils.
10

The use of in vitro assays to screen for endocrine modulation.

Hendricks, Rahzia. January 2008 (has links)
<p>&nbsp / </p> <p align="left"><font face="Times New Roman">Aspalathus linearis (A. linearis), </font><font face="Times New Roman">commonly known as Rooibos tea or Red bush tea and </font><i><font face="Times New Roman">amellia sinensis (C. sinensis) </font></i><font face="Times New Roman">or Black tea are beverages that are consumed throughout the</font><font face="Times New Roman">world. These teas possess antioxidant, immunomodulating and anti-cancer actions. The aim</font> <font face="Times New Roman">of this study was to use <i>in vitro </i>assays to screen Rooibos and Black tea for endocrine</font> <font face="Times New Roman">modulation. </font><font face="Times New Roman">The immune modulating effects of Rooibos and Black tea were investigated using an <i>in vitro</i></font> <font face="Times New Roman">whole blood culture (WBC) assay. Unstimulated WBCs treated with Rooibos tea secreted</font> <font face="Times New Roman">higher levels of IL-6, IL-10 and IFN<font lang="JA">&gamma / </font>than cultures treated with DMSO control. Rooibos treatment of stimulated WBCs resulted in higher IL-6, lower IL-10 and no effect on IFN&gamma / </font><font face="Times New Roman">secretion compared to DMSO treated stimulated WBC. Black tea treatment of stimulated</font> <font face="Times New Roman">WBC resulted in decreased IL-6, IL-10 and IFN<font lang="JA">&gamma / </font>secretion compared to the DMSO treated</font> <font face="Times New Roman">stimulated WBC. </font><font face="Times New Roman">Extracts of Rooibos and Black tea were assessed for phytoestrogens using quantitative </font><font face="Times New Roman">estrogen ELISAs. Both teas contain phytoestrogens. The quantitative ELISAs showed that </font><font face="Times New Roman">Rooibos tea contained significantly lower estrone (E1), estradiol (E2) and estriol (E3) levels </font><font face="Times New Roman">than Black tea. The effects of Rooibos and Black tea on proliferation of the estrogen</font> <font face="Times New Roman">dependant MCF-7 cell line was determined to further characterise the phytoestrogenic</font> <font face="Times New Roman">properties of the teas. Both Rooibos and Black tea extracts caused a significant inhibition of</font> <font face="Times New Roman">MCF-7 proliferation. </font><font face="Times New Roman">This study shows that Rooibos tea and Black tea are beverages that can either stimulate or </font><font face="Times New Roman">suppress the immune system. Also, both teas contain significant levels of phytoestrogens as </font><font face="Times New Roman">determined by quantitative ELISAs. The current study confirms previous reports showing </font><font face="Times New Roman">inhibition of growth in breast cancer cell lines by phytoestrogens. The findings extend </font><font face="Times New Roman">related observations on the anti-carcinogenic potential of the two teas.</font></p>

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