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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

Development of an analytical method for the evaluation of N,N-dimethylformamide in dosage form design

Olivier, EI, Du Toit, D, Hamman, JH 25 September 2007 (has links)
N,N-Dimethylformamide (DMF) is a well-known chemical entity that is extensively used for pharmaceutical, biomedical and chemical applications. Previous research identified the need for the development of an effective dosage form for the systemic delivery of DMF due to its unique antiviral properties. For purposes of quality control and evaluation during pharmaceutical product development, development of an analytical method was required. A gas chromatographic (GC) method was developed with a flame-ionization detector (FID) on a carbowax packed glass column. 2-Methoxyethanol was used as internal standard. The analytical method proved to be capable of separating DMF and 2-methoxyethanol adequately within a relatively short runtime of 2.5 min. The analytical method described was primarily developed for use in dissolution studies of DMF containing delivery systems. Various physicochemical properties of candidate internal standard materials were correlated with the observed retention times of these compounds. The best correlation (r2 ¼ 0.8077) was obtained between the boiling point and the retention time of the compounds for the current application. The boiling point of an internal standard candidate material may therefore be useful in predicting the retention time of that compound under similar conditions.
2

Studies on the characterization, biosynthesis and isolation of starch and protein from quinoa (<i>Chenopodium quinoa</i> Willd.)

Lindeboom, Nienke 15 August 2005
Starches isolated from sixteen quinoa lines ranged in amylose content from 3 to 20%. With the exception of pasting temperature, large variations in pasting characteristics were found among starches and were correlated with amylose content. The gelatinization onset (44.7-53.7 ºC) and peak (50.5-61.7 ºC) temperatures and retrogradation tendencies (19.6-40.8%) were positively correlated with amylose content. No significant variation in gelatinization enthalpy was observed. Swelling, solubility, freeze-thaw stability and water-binding capacity also differed among starches and were correlated with amylose content. The wide variation in amylose content and physicochemical characteristics among quinoa starches suggests applications in a variety of food and non-food products. Two major polypeptides with apparent molecular masses of 56 and 62 kDa were present in quinoa starch and were identified as isoforms of Granule Bound Starch Synthase I (GBSSI). The content of the two isoforms was positively correlated with the concentration of amylose in starch. Starch synthase activity in developing seed was positively correlated with the amylose concentration in starch during seed development. An integrated process was developed for the fractionation of quinoa into starch, protein, oil and saponins. Seed was first roller milled, yielding a coarse bran fraction (48% of the seed weight) that was high in protein (22.9%, db), oil (8.8%, db), and saponins (7.4%, db), and a fine, starch-rich fraction [52% of the seed weight containing 77.2% (db) starch]. Protein, oil and saponins were extracted from the bran under optimized conditions. The protein extracts were concentrated and purified using isoelectric precipitation or ultrafiltration. The means of concentration as well as the presence of saponins strongly affected protein recovery and functionality. Starch was recovered using aqueous alkali (pH 9) to solubilize the protein followed by centrifugation, after which the starch-rich pellet was washed and the sediment which accumulated on top of the pellet was removed. The end-products of the integrated extraction process were a crude saponin extract, a crude oil product, and several protein and starch products. Forty-one percent of the protein present in the seed was recovered as a protein product that contained over 77% (db) protein. Sixty-eight percent of the starch was recovered as a starch product that contained 97% (db) starch and 1.2% (db) protein.
3

Studies on the characterization, biosynthesis and isolation of starch and protein from quinoa (<i>Chenopodium quinoa</i> Willd.)

Lindeboom, Nienke 15 August 2005 (has links)
Starches isolated from sixteen quinoa lines ranged in amylose content from 3 to 20%. With the exception of pasting temperature, large variations in pasting characteristics were found among starches and were correlated with amylose content. The gelatinization onset (44.7-53.7 ºC) and peak (50.5-61.7 ºC) temperatures and retrogradation tendencies (19.6-40.8%) were positively correlated with amylose content. No significant variation in gelatinization enthalpy was observed. Swelling, solubility, freeze-thaw stability and water-binding capacity also differed among starches and were correlated with amylose content. The wide variation in amylose content and physicochemical characteristics among quinoa starches suggests applications in a variety of food and non-food products. Two major polypeptides with apparent molecular masses of 56 and 62 kDa were present in quinoa starch and were identified as isoforms of Granule Bound Starch Synthase I (GBSSI). The content of the two isoforms was positively correlated with the concentration of amylose in starch. Starch synthase activity in developing seed was positively correlated with the amylose concentration in starch during seed development. An integrated process was developed for the fractionation of quinoa into starch, protein, oil and saponins. Seed was first roller milled, yielding a coarse bran fraction (48% of the seed weight) that was high in protein (22.9%, db), oil (8.8%, db), and saponins (7.4%, db), and a fine, starch-rich fraction [52% of the seed weight containing 77.2% (db) starch]. Protein, oil and saponins were extracted from the bran under optimized conditions. The protein extracts were concentrated and purified using isoelectric precipitation or ultrafiltration. The means of concentration as well as the presence of saponins strongly affected protein recovery and functionality. Starch was recovered using aqueous alkali (pH 9) to solubilize the protein followed by centrifugation, after which the starch-rich pellet was washed and the sediment which accumulated on top of the pellet was removed. The end-products of the integrated extraction process were a crude saponin extract, a crude oil product, and several protein and starch products. Forty-one percent of the protein present in the seed was recovered as a protein product that contained over 77% (db) protein. Sixty-eight percent of the starch was recovered as a starch product that contained 97% (db) starch and 1.2% (db) protein.
4

Physicochemical properties and isoflavone content of bread made with soy

Zhang, Yu Chu 30 September 2004 (has links)
No description available.
5

Síntese, dopagem e caracterização das resinas furfurílica e fenol-furfurílica visando a otimização do processamento de carbono vítreo

Oishi, Silvia Sizuka [UNESP] 29 June 2009 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:27:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-29Bitstream added on 2014-06-13T20:35:16Z : No. of bitstreams: 1 oishi_ss_me_guara.pdf: 1972224 bytes, checksum: 3c999656c713b895ba43f4e61fdba9fd (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Em função da crescente importância do material carbono vítreo em áreas estratégicas, devido às suas características intrínsecas, tais como menor massa específica e bons valores de condutividades térmica e elétrica, tem se observado vários estudos na busca de novos precursores poliméricos, assim como no ajuste mais sistemático de seu processamento. Nesse sentido, este trabalho tem como objetivo o estabelecimento de rotas de síntese de resinas furfurílica e fenol-furfurílica e suas dopagens com partículas de cobre, visando o processamento de eletrodos de carbono vítreo reticulado (CVR). Neste contexto foram sintetizadas diferentes formulações de resinas furfurílica e fenol-furfurílica a partir da variação dos monômeros – álcool furfurílico, fenol e formaldeído, respectivamente. A confirmação do sucesso das sínteses foi realizada por análises de espectroscopia de infravermelho com transformada de Fourier, cromatografia gasosa, análises térmicas por calorimetria exploratória diferencial e medidas dos teores de carbono fixo, que mostram resultados entre 27 e 45% em carbono. Em seguida, estas amostras foram dopadas com um colóide contendo as partículas de cobre. As resinas, com e sem dopagem, foram catalisadas, impregnadas em espumas de poliuretano (PU) e carbonizadas, obtendo-se assim, o CVR. Análises por microscopias óptica e eletrônica de varredura mostram a homogeneidade na impregnação das espumas de PU e a textura uniforme das amostras de CVR. Os resultados de resistência à compressão apresentam os melhores valores para o CVR resultante da carbonização com a resina furfurílica ácida (0,55 MPa). / Due to the growing importance of glassy carbon material in strategic areas, due to its intrinsic characteristics, such as lower density and good thermal and electrical conductivities values, has been observed several studies looking for new polymeric precursors and tighter processing parameters. In this way, this study aims on the establishment of synthesis routes of furfuryl and phenol-furfuryl alcohol resins and their doping with cupper particles, in order to produce reticulated glassy carbon (RGC) electrodes. Inside of this context were synthesized different formulations of furfuryl and phenol-furfuryl alcohol resins by the monomers variation – furfuryl alcohol, phenol and formaldehyde, respectively. The success confirmation of the synthesis has been done by using FT-IR spectroscopy, gas chromatography, thermal analyses by differential scanning calorimetry (DSC) and carbon yield content measurements that present results between 27 and 45% of carbon. After this, the specimens were doped with a colloid contend the copper particles. The doped and non doped resins were catalyzed, impregnated in polyuretane (PU) foams and carbonized, in order to obtain the reticulated glassy carbon. Optical and Scanning Electron Microscopy analysis show the homogeneity of PU foams impregnation and uniform texture of RGC specimens. Compression results present the best values for RGC resulting from the carbonization with furfuryl alcohol acid resin (0,55 MPa).
6

Faixas de condutividade elétrica no desenvolvimento e características físico-químicas de pimentão pé-franco e enxertado / Electric conductivity standards in development and physico-chemical characteristics of ungrafted and grafted bell pepper

Silva, Jéssica Danila [UNESP] 24 August 2017 (has links)
Submitted by Jéssica Danila Silva null (duarte.jessicasilva@gmail.com) on 2017-09-29T18:36:33Z No. of bitstreams: 1 DISSERTAÇÃO.9 VERSÃO FINAL IMPRESSÃO completa.pdf: 1834458 bytes, checksum: 01113398a70288fa7f27f591df665130 (MD5) / Approved for entry into archive by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-09-29T19:23:04Z (GMT) No. of bitstreams: 1 silva_jd_me_bot.pdf: 1834458 bytes, checksum: 01113398a70288fa7f27f591df665130 (MD5) / Made available in DSpace on 2017-09-29T19:23:04Z (GMT). No. of bitstreams: 1 silva_jd_me_bot.pdf: 1834458 bytes, checksum: 01113398a70288fa7f27f591df665130 (MD5) Previous issue date: 2017-08-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O pimentão é uma das hortaliças brasileiras de maior expressão, que em virtude de seu alto valor de comercialização está sempre empregando novas tecnologias de manejo que possam aprimorar a eficiência das técnicas de cultivo, reduzindo custos de produção e incrementando a produtividade e qualidade. Uma das principais ferramentas para o monitoramento da evolução dos processos de salinização apresenta-se como a aferição da condutividade elétrica (EC) do solo e/ou substrato. O conhecimento da composição química da solução do solo e/ou substrato é de extrema importância, uma vez que determinadas concentrações salinas são capazes de provocar distúrbios funcionais e metabólitos, bem como redução do potencial total de água no solo e/ou substrato e consequentemente, alterações sobre a disponibilidade de nutrientes para a cultura. Assim, foram avaliadas três faixas de condutividade elétrica sob as condições pé-franco e enxertado para os híbridos Anabell, Cida, Don Santino, Magali, Melina e El Jefe, conduzidos em substrato. Este trabalho foi composto por seis experimentos, conduzidos em ambiente protegido, na Estação Experimental Sakata, pertencente à Sakata Seed Sudamérica, Bragança Paulista/SP. O delineamento experimental para cada material genético utilizado foi um fatorial 3 x 2 (três faixas de condutividade elétrica (1,0 - 2,0; 2,5 - 3,5 e 4,0 - 5,0 dSm-1) e duas condições: pé-franco e enxertado) com quatro repetições, sendo cada parcela composta por cinco vasos com uma planta cada. As características avaliadas foram: altura de plantas; diâmetro do caule; número de frutos fixados por planta; número de frutos colhidos por planta e massa fresca média de frutos. As características físico-químicas avaliadas foram sólidos solúveis; pH; acidez total; açúcar redutor e ácido ascórbico. Nas condições avaliadas conclui-se que as melhores condições de desenvolvimento estão nas faixas de 2,5 – 3,5 dSm-1 para os híbridos Magali enxertado, Melina e pimenta El Jefe e 4,0 – 5,0 dSm-1 para os híbridos Anabell pé-franco, Cida enxertado e Don Santino pé-franco. As características físico-químicas relacionadas a qualidade de frutos sofreram pouca influência dos tratamentos, apresentando dados semelhantes aos descritos pela literatura existente referente a cada análise. / The bell pepper is one of the most important Brazilian vegetables, which, due to its high commercial value, is always employing new management technologies that can improve the efficiency of cultivation techniques, reducing production costs and increasing productivity and quality. One of the main tools for monitoring the evolution of salinization processes is the measurement of the soil electrical conductivity (EC). The knowledge of the chemical composition of the soil solution is of extreme importance, since certain salt concentrations are capable of causing functional disturbances and metabolites, as well as reduction of the total potential of water in the soil and consequently, changes in the availability of nutrients for the soil. culture. Thus, three standard of electrical conductivity ungrafted and grafted conditions were evaluated for the hybrids Anabell, Cida, Don Santino, Magali, Melina and El Jefe. This work was composed of six experiments, conducted in protected environment, at the Sakata Experimental Station, belonging to Sakata Seed South America, Bragança Paulista/SP. The experimental design for each genetic material used was a 3 x 2 factorial (three standard of electrical conductivity (1.0 - 2.0, 2.5 - 3.5 and 4.0 - 5.0 dSm-1) and two conditions: ungrafted and grafted) with four replicates, each plot consisting of five pots with one plant each. The evaluated characteristics were: height of plants; stem diameter; number of fruits fixed per plant; number of fruits harvested per plant and average fresh mass of fruits. The physical-chemical characteristics evaluated were soluble solids; pH; total acidity; reducing sugar and ascorbic acid. Under the conditions evaluated, it is concluded that the best development conditions are in the 2.5 - 3.5 dSm-1 ranges for the grafted Magali hybrids, Melina and El Jefe pepper and 4.0 - 5.0 dSm-1 for the Anabell hybrids ungrafted, Cida grafted and Don Santino ungrafted. The physicochemical characteristics related to fruit quality had little influence on the treatments, presenting data similar to those described in the literature regarding each analysis.
7

A supramolecular derivatised study of BIS(Adamantan-1- Aminium) carbonate

Ngilirabanga, Jean Baptiste January 2014 (has links)
Magister Pharmaceuticae - MPharm / In this study, new solid supramolecular derivatised forms of bis(adamantine-1-aminium) carbonate (ADTCO3) were prepared. ADTCO3 is a derivative of amantadine used for Parkinson’s disease and has antiviral properties against influenza-A, dengue fever and pharmacological activity towards Parkinson’s disease. The new forms prepared were polymorphic and co-crystal forms of ADTCO3. Polymorphism is a phenomenon where the ability of a substance to exist in two or more crystalline forms occurs when crystallised under different conditions and co-crystallization is the process of formation of multicomponent crystals of a drug substance. New solid forms often display different mechanical, physicochemical and thermal properties that can remarkably influence the bioavailability, hygroscopicity and stability of active pharmaceutical ingredients (APIs). For the formation of polymorphs of ADTCO3, techniques such as dry grinding, solvent-drop grinding, co-precipitation, sublimation and vapour diffusion were applied. For the development of co-crystals and/or complex formation, ADTCO3 was treated in combination with ten selected co-formers viz; benzoic acid, 4-hydroxybenzoic acid, cinnamic acid, 4-hydroxycinnamic acid, succinic acid, tartaric acid, salicylic acid, L-glutamic acid, citric acid monohydrate and L-glutaric acid using similar techniques as applied in the polymorphism study. The first four co-formers were selected for their potential biological activity and the latter six were selected for their generally regarded as safe (GRAS) status. All products were isolated and characterized using different analytical techniques to assess the thermal behaviour of the products by hot stage microscopy (HSM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). FTIR spectroscopy and proton-nuclear magnetic resonance (1HNMR) were used to identify and determine the purity of the parent compounds and the modified forms. X-ray powder diffraction was used to determine the formation of a new phase and single crystal X-ray diffraction was applied at the initial stages to identify ADTCO3 by its unit cell parameters. Furthermore, the Cambridge Structural Database (CSD) and other resources were used to generate information on the molecular structures of all elucidated parent compounds, their polymorphs and reported co-crystals. Four different polymorphic forms of ADTCO3 were identified (viz. ADTCO3 Forms I to IV) and sixteen co-crystals (viz. ADTCO3BA1 to ADTCO3BA5, ADTCO3HBA, ADTCO3CIN, ADTCO3HCIN, ADTCO3SUC, ADTCO3LTTA, ADTCO3SA, ADTCO3CA, ADTCO3GLA, ADTCO3GA) were synthesised. Of the sixteen co-crystals 5 were identified as ADTCO3BA “salt” co-crystal polymorphic forms and 2 as ADTCO3SUC co-crystal polymorphic forms. Two solvated “salt” co-crystal forms were also identified, namely; ADTCO3GLA and ADTCO3LTTA. ADTCO3GLA had a mass loss of 10.3% (n = 2.4) and ADTCO3LTTA had a mass loss of 5.25% (n = 0.86). Finally, the rest of the co-crystals ADTCO3HBA, ADTCO3CIN, ADTCO3HCIN, ADTCO3SA, ADTCO3CA and ADTCO3GA all crystallised as “salt” co-crystals.
8

Using physicochemical and compositional characteristics of DNA sequence for prediction of genomic signals

Mulamba, Pierre Abraham 12 1900 (has links)
The challenge in finding genes in eukaryotic organisms using computational methods is an ongoing problem in the biology. Based on various genomic signals found in eukaryotic genomes, this problem can be divided into many different sub­-problems such as identification of transcription start sites, translation initiation sites, splice sites, poly (A) signals, etc. Each sub-­problem deals with a particular type of genomic signals and various computational methods are used to solve each sub-­problem. Aggregating information from all these individual sub-­problems can lead to a complete annotation of a gene and its component signals. The fundamental principle of most of these computational methods is the mapping principle – building an input-­output model for the prediction of a particular genomic signal based on a set of known input signals and their corresponding output signal. The type of input signals used to build the model is an essential element in most of these computational methods. The common factor of most of these methods is that they are mainly based on the statistical analysis of the basic nucleotide sequence string composition. 4 Our study is based on a novel approach to predict genomic signals in which uniquely generated structural profiles that combine compressed physicochemical properties with topological and compositional properties of DNA sequences are used to develop machine learning predictive models. The compression of the physicochemical properties is made using principal component analysis transformation. Our ideas are evaluated through prediction models of canonical splice sites using support vector machine models. We demonstrate across several species that the proposed methodology has resulted in the most accurate splice site predictors that are publicly available or described. We believe that the approach in this study is quite general and has various applications in other biological modeling problems.
9

Improvement of the Physicochemical Attributes and Antioxidants Profiles from Pulse Seeds through Germination

Xu, Minwei January 2019 (has links)
Edible pulse seeds are good sources of food ingredients. Germination has been regarded as an effective process to further improve nutrient digestibility and accessibility of pulse seeds. Our aim was to observe the effect of germination on proximate composition, physicochemical attributes, and phenolic profiles of chickpea (Cicer arietinum L.), lentil (Lens culinaris Merr.), and yellow pea (Pisum sativum L.). In addition, mechanisms of how germination affects the antioxidant activity of phenolic compounds were proposed. Chemical composition, thermal, pasting, and moisture adsorption properties of pulse flours were investigated over 6 days of germination. Protein contents increased by 3 percent points for all pulses over germination. However, lentil had the highest protein content. Lipid contents decreased over germination with chickpea having the greatest decline, from 8.00 to 5.90 g/100g (d.b.). Total starch decreased in lentil and yellow pea during germination. Thermal properties of pulse flours changed slightly, while pasting properties varied among pulses. The highest final viscosities for chickpea, lentil, and yellow pea flours were 1061, 981, and 1052 cP and were observed after 2, 1, and 0 days of germination, respectively. Moisture adsorption isotherms showed improved water adsorption capabilities after germination. Soluble free (SFPs) and polar soluble bound phenolic compounds (PSBPs) were extracted from germinated pulse seeds. Their antioxidant activities were evaluated using both the in vitro system and stripped soybean oil (SSO)-in-water emulsions. Liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry and size-exclusion chromatography with multiangle-light-scattering and refractive-index detection were employed to analyze the phenolic composition and molar mass, respectively. Antioxidant activities of SFPs increased in both in vitro and SSO-in-water emulsion system, however, much lower than those of PSBPs based on SSO-in-water emulsion system. The effect of germination on PSBPs in SSO-in-water emulsion varied between pulses. By virtue of chemometric analysis, nine phenolic compounds were speculated as the pivotal phenolic compounds responsible for the antioxidant activity of PSBPs. In particular, the molar masses of PSBPs had a positive relationship with their antioxidant activity. Protective and co-antioxidative principles were proposed as reasons for the variability of antioxidant activities of PSBPs in oil-in-water emulsions with germination. / Hatch project number ND01593
10

Physicochemical and antibacterial characterization of a novel fluorapatite coating

Alhilou, A., Do, T., Mizban, L., Clarkson, B.H., Wood, David J., Katsikogianni, Maria G. 26 August 2016 (has links)
Yes / Peri-implantitis remains the major impediment to the long-term use of dental implants. With increasing concern over the growth in antibiotic resistance, there is considerable interest in the preparation of antimicrobial dental implant coatings that also induce osseointegration. One such potential coating material is fluorapatite (FA). The aim of this study was to relate the antibacterial effectiveness of FA coatings against pathogens implicated in peri-implantitis to the physicochemical properties of the coating. Ordered and disordered FA coatings were produced on the under and upper surfaces of stainless steel (SS) discs, respectively, using a hydrothermal method. Surface charge, surface roughness, wettability, and fluoride release were measured for each coating. Surface chemistry was assessed using X-ray photoelectron spectroscopy and FA crystallinity using X-ray diffraction. Antibacterial activity against periodontopathogens was assessed in vitro using viable counts, confocal microscopy, and scanning electron microscopy (SEM). SEM showed that the hydrothermal method produced FA coatings that were predominately aligned perpendicular to the SS substrate or disordered FA coatings consisting of randomly aligned rodlike crystals. Both FA coatings significantly reduced the growth of all examined bacterial strains in comparison to the control. The FA coatings, especially the disordered ones, presented significantly lower charge, greater roughness, and higher area when compared to the control, enhancing bacteria−material interactions and therefore bacterial deactivation by fluoride ions. The ordered FA layer reduced not only bacterial viability but adhesion too. The ordered FA crystals produced as a potential novel implant coating showed significant antibacterial activity against bacteria implicated in peri-implantitis, which could be explained by a detailed understanding of their physicochemical properties. / This work was partially funded through WELMEC, a Centre of Excellence in Medical Engineering funded by the Wellcome Trust and EPSRC, under grant number WT 088908/Z/09/Z.

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