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1
Durst, Gregory L. "Conformational analysis of phosphine ligands, using molecular mechanics and cone angle calculations." Virtual Press, 1988. http://liblink.bsu.edu/uhtbin/catkey/539633.
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An empirical approach to the study of phosphine compounds was completed using Molecular Mechanics 2 (MM2), and several computer programs written to descibe and analyze the final geometric orientations of the molecules. The calculations were performed on 64 conformers of 16 different phosphines. Results from these calculations were compared to those previously obtained for MNDO and MINDO/3 calculations, and to experimental data. Cone angles calculated from the MM2 optimized geometries, were compared to Tolman's original work, and to values obtained from semiempirical calculations, and to experimental results. In general, it was found that weighted average cone angles best represent the size of phosphine ligands.<br>Department of Chemistry
2
Ting, Fai Lung. "The chemistry of osmium and ruthenium carbonyl clusters with functionalized alkyne and phosphine ligands." HKBU Institutional Repository, 2001. http://repository.hkbu.edu.hk/etd_ra/296.
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Schlipalius, David Ian. "Molecular genetics and linkage analysis of phosphine resistance in the lesser grain borer, rhyzopertha dominica (coleoptera: bostrichidae) /." [St. Lucia, Qld], 2004. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18219.pdf.
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Zhang, Yuanzhe. "Pd/azaborine-biaryl phosphine complexes: reaction development, mechanistic analysis, and investigations into metal-ligand coordination dynamics." Thesis, Boston College, 2021. http://hdl.handle.net/2345/bc-ir:109152.
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Thesis advisor: Shih-Yuan Liu<br>Described herein are three research projects that focused on 1) the catalytic activities of Pd/azaborine-derived biary phosphine (Senphos) complexes in 1,3-enyne difunctionalization reactions and 2) the coordination behaviors of these Pd/Senphos complexes. In the first chapter, expansion of the substrate scope and mechanistic studies of the reported Pd/Senphos catalyzed site-, regio- and trans-selective hydroboration of 1,3- enynes are described. In the second chapter, the first intermolecular site-, regio- and transselective chloroboration and cyanoboration of enynes that are enabled by the Pd/Senphos catalytic system are presented. The cyanoboration products, namely vicinal boronsubstituted alkenylnitriles, are demonstrated as versatile synthetic building blocks. In the last chapter, the κ2-P-η2-B,C coordination behavior in a series of 1,2-, 1,3- and 1,4-Senphos ligated Pd(0) or Pd(II) complexes are evaluated based on solid-state structures and variable-temperature NMR measurements<br>Thesis (PhD) — Boston College, 2021<br>Submitted to: Boston College. Graduate School of Arts and Sciences<br>Discipline: Chemistry
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Plumier, Benjamin Mark. "3D ecosystem modeling of aeration and fumigation in Australian grain silos to improve efficacy against insects." Diss., Kansas State University, 2018. http://hdl.handle.net/2097/38833.
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Doctor of Philosophy<br>Department of Grain Science and Industry<br>X. Susan Sun<br>With continued population growth, more food production will be required with lower resource inputs. A significant drain on resources is post-harvest loss due to insects, which results in loss of product, quality and market access, and increased grain spoilage. Aeration and fumigation are key tools to control insect growth in stored grains and grain foods. The implementation of aeration strategies in Australia is made difficult by the warm subtropical climate, meanwhile the success of fumigation is being threatened by the spread of insect resistance to the fumigant phosphine. This dissertation project seeks to improve the understanding of aeration and fumigation by modifying the Maier-Lawrence (M-L) 3D ecosystem model by adding insect growth equations and quantifying fumigant loss from sealed bulk grain silos. The improved model was used to examine aeration under Australian conditions, validate its capability to accurately describe fumigant concentrations during silo fumigation, determine the extent to which fumigations are influenced by operational variables and environmental conditions, and validate its capability to describe fumigant concentrations post-fumigation in order to investigate the time needed to clear a grain storage silo of fumigant in order to assure worker safety.
Six aeration strategies were evaluated under Australian conditions. Of these strategies, two were found to be effective in lowering temperatures, i.e., fans were turned on when ambient temperature was less than 20oC, and less than internal grain temperature. The strategy based on temperature differential was the most effective because it cooled the interior of the grain mass with the least amount of energy (using the fewest fan run hours, and reaching 15oC an average of 11 days after than the fastest strategy). Using a 0oC temperature differential was the most effective strategy in terms of reducing insect growth.
The expanded (M-L-P) model was then validated based on experimental fumigant concentrations. The model was effective in reproducing average fumigant concentrations and fumigant trends vertically through the grain mass, but was not able to reproduce lateral fumigant variations. Verifications of the model with two different periods of phosphine release (i.e., 24h and 30h) were tested. Based on a 24h phosphine release period the predicted Ct-product differed from the experimental value by 0.9%. A 30h release period predicted a Ct-product that differed by 4.3% from the experimental value but it was more accurate during the times of highest concentration. Increases in leakage reduced fumigant concentrations, but the size of the effect decreased as leakage grew. Increasing temperature and wind speed in the model led to decreased phosphine concentrations, with temperature changes having a more significant impact overall than wind speed changes for the conditions investigated. Decreasing silo surface area to volume ratio dampened the impact of changing weather conditions on phosphine concentrations.
A fumigant venting experiment was conducted in a silo at Lake Grace, Australia, to investigate full scale desorption. Two equations estimating fumigant desorption were tested, with an average of 65.5% and -86.3% error. The length of venting periods was simulated to quantify hours needed to mitigate hazardous conditions. For the scenarios investigated 10 to 24 h of venting were needed to reduce residual fumigant concentration below 0.3 ppm depending on simulation assumptions.
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Li, Chi-kwan, and 李志君. "Gold(I) and Gold(II) phosphine complexes exhibiting weak AuI... AuI interactions and unsupported AuII-AuII bonds: syntheses, spectroscopy, host-guest chemistry and reactivity studies." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B31243332.
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Korb, Marcus. "Anionic Phospho-Fries Rearrangements for the Synthesis of Planar-Chiral Ferrocenes and their Application in (atropselective) Suzuki-Miyaura Reactions." Doctoral thesis, Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-229081.
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The present PhD thesis describes the synthesis and characterization of novel planarchiral 1,2-P,O-ferrocenes and their application in the Pd-catalyzed Suzuki-Miyaura reaction. It was especially focused on the development of a new synthetic pathway to this type of substitution pattern by applying the anionic phospho-Fries rearrangement in ferrocene chemistry. Starting from hydroxy ferrocene, a high diversity of Fc–O–P- type (Fc = (n5-C5H5)(n5-C5H4)) compounds were synthesized, whereby the electronic properties of the phosphorus fragments were varied. The anionic phospho-Fries rearrangement successfully occurred subsequent to an ortho-lithiation with a non-nucleophilic base giving the 1,2-P,O-ferrocenes in up to quantitative yields. The usage of chiral pool-based alcohols for the synthesis of chiral ferrocenyl phosphates allowed a diastereoselective proceeding, giving single isomers in up to 95% de. Temperature-dependent investigations of mixed ferrocenyl-, phenyl- and Nheterocyclicphosphates revealed a limitation of ferrocenyl-based rearrangements per reaction step, contrary to phenyls. 1,2-P,O-ferrocenyl phosphonates could successfully be converted into phosphines by applying Stelzer P,C cross-coupling reactions on ferrocenes for the first time. Their usage as ligands for C,C cross-coupling reactions was confirmed by the synthesis of sterically hindered biaryls in high yields at 70°C with a low catalyst loading of 1 mol-% Pd. Functionalization of the 1,2-P,O -structural motif could be achieved by applying nucleophilic aromatic substitution reactions (SNAr) as an alternative pathway for the synthesis of ferrocenyl aryl ethers. Subsequent to a Fries rearrangement sterically-demanding 1,3-di-orthosubstituted aryloxy ferrocenes could be obtained. Multi SNAr reactions of hydroxyferrocenes at polyfluorinated arenes gave up to pentaferrocenyl-functionalized aryl ethers, whose electrochemical properties were investigated. The reaction of CH2-enlarged ferrocenylmethanols gave α-ferrocenylcarbenium ions instead of phosphates, while treating them with chlorophosphates. Enantiopure 2-P(S)Ph2-substituted derivatives of these ions underwent a subsequent intermolecular “S2−“ migration, resulting in thioethers, for example (Sp,Sp)-(2-(P(S)Ph2)FcCH2)2S, in a unique mechanism. Instead, the presence of electronrich arenes gave electrophilic aromatic substituted benzenes bearing chiral ferrocenylmethyl backbones. These type of ligands gave biaryls with up to 26 % ee<br>Die vorliegende Arbeit beschäftigt sich mit der Synthese und Charakterisierung von neuartigen planar-chiralen 1,2-P,O-ferrocenen sowie deren Anwendung in der Pd-katalysierten Suzuki-Miyaura Reaktion. Dabei lag der Focus in der Anwendung anionischer phospho-Fries Verschiebungen auf Ferrocene um dieses spezielle Substitutionsmuster erhalten zu können. Ausgehend von Hydroxyferrocenen wurde so eine Vielzahl neuer Verbindungen des Typs Fc–O–P (Fc = (n5-C5H5)(n5-C5H4)) synthetisiert, wobei die elektronischen Eigenschaften des Phosphor-tragenden Fragmentes variiert wurden. Die anionische phospho-Fries Verschiebung erfolgte im Anschluss einer ortho-Lithiierung mit einer nicht-nucleophilen Base, was 1,2-P,O-Ferrocene nahezu quantitative ergab. Durch die Verwendung von chiral-pool basierten Alkoholen für die Synthese chiraler Ferrocenylphosphate konnte eine diastereoselective 1,3-O->C Umlagerung mit Isomerenreinheiten von bis zu 95 % erreicht werden. Untersuchungen von gemischten Ferrocenyl-, Phenyl- und N-heterocyclischen Phosphaten bei verschiedenen Temperaturen zeigte eine Limitierung Ferrocenyl-basierter Umlagerungen pro Reaktionsschritt im Gegensatz zu denen von Phenylen. Die erhaltenen 1,2-P,O-Ferrocenylphosphate wurden erstmals mittels Stelzer P,C Kreuz-Kupplungsreaktionen erfolgreich in Phosphane umgesetzt. Deren Verwendung als Ligand in C,C Kreuz-Kupplungsreaktionen wurde am Beispiel der Synthese räumlich anspruchsvoller Biaryle in hohen Ausbeuten bei nur 70°C und niedrigen Katalysatorbeladungen von 1 mol-% Pd demonstriert. Die Funktionalisierung des 1,2-P,O-Strukturmotifes konnte durch die Anwendung von nucleophilen aromatischen Substitutionsreaktionen erreicht werden, die einen alternativen Zugang zu Ferrocenylarylethern bietet. Im Anschluss an eine Fries Umlagerung konnten so sterisch anspruchsvolle 1,3-di-ortho-substituierte Ferrocenylarylether erhalten werden. Durch mehrfache SNAr Reaktionen von Hydroxyferrocenen an polyfluorierten Aromaten wurden bis zu fünf-fach substituierte Ether erhalten, deren elektrochemischen Eigenschaften untersucht wurden. Die um eine CH2-Einheit verlängerten Ferrocenylmethanole gaben bei Reaktion mit Chlorophosphaten alpha Ferrocenylcarbeniumionen anstelle der gewünschten Phosphate. Enantiomerenreine 2-P(S)Ph2-substituierte Derivate dieser Ionen durchliefen anschließend einen intermolekularen ”S2–“ Transfer in einem einzigartigen Mechanismus, was bspw. in Thioethern des Typs (Sp,Sp)-(2-(P(S)Ph2)FcCH2)2S resultierte. In Anwesenheit elektronenreicher Aromaten wurden elektrophile aromatischen Substitutuionen und die Bildung chiraler ferrocenylmethyl-substitutuierter Benzene beobachtet. Deren Einsatz als Ligand ergab Biaryle mit bis zu 26 % ee
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Philippon, David. "Lubrification par la phase gazeuse : tribochimie des additifs phosphorés et boratés." Phd thesis, Ecole Centrale de Lyon, 2007. http://tel.archives-ouvertes.fr/tel-00280892.
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La formulation des lubrifiants utilisés dans l'automobile est complexe du fait du nombre important d'additifs mélangés aux huiles de base. Pour orienter le choix des formulateurs, il est non seulement nécessaire de connaître le mécanisme d'action de chaque additif mais aussi les interactions entre ces additifs. Pour mieux appréhender ces mécanismes, une démarche originale a été mise en place dans cette étude. Celle-ci consiste à simuler expérimentalement la lubrification en régime limite par la lubrification en phase gazeuse. Pour cela, des molécules de faible poids moléculaire modélisant les différents constituants d'un lubrifiant ont été introduites sous ultravide. Ce type d'expérience a pu être réalisé grâce au développement d'un nouveau Tribomètre à Environnement Contrôlé (TEC) connecté à un système d'analyse de surface. Cette technique permet de simplifier le système tribologique et d'étudier in situ les tribofilms formés en phase gazeuse par des analyses de surface (XPS/AES). Différentes molécules ont été étudiées : triméthylborate (TMB), triméthylphosphite (TMPi) et triméthylphosphate (TMPa) modélisant respectivement les additifs boratés et phosphorés des lubrifiants de transmission. Cette simulation expérimentale a pu être validée en comparant les résultats en phase gazeuse avec ceux obtenus en phase liquide. Des observations en microscopie optique et des analyses chimiques ont mis en évidence la formation de tribofilms. Les expériences réalisées en présence de TMB ont permis de confirmer les résultats de la littérature sur la formation d'un tribofilm non sacrificiel de borates de type « minéral ». Les expériences réalisées avec les molécules phosphorées ont permis de montrer la différence entre les phosphates et les phosphites, notamment la formation d'un composé de type phosphure de fer en présence de TMPi. Les analyses in situ sur les tribofilms obtenus en présence de TMPi ont permis de déterminer le mécanisme de formation du composé phosphure de fer. La réalisation de mélanges de gaz a permis également de mettre en avant les effets de synergie et d'antagonisme entre les additifs
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Scullion, Stanley Paul. "Amperometric monitoring of nitrate and phosphate." Thesis, Loughborough University, 1989. https://dspace.lboro.ac.uk/2134/26816.
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Methods are presented here for the determination of nitrate by electrochemical techniques. The reaction of nitrate with various organic reagents was studied by differential pulse polarography and a method described based on the nitration of benzoic acid. A rectilinear response was obtained over a 10-6 to 5x10-3M concentration range with reproducibility of < 2% at higher nitrate concentrations.
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Mambingo, Doumbe Samuel. "Simulation de la phase gazeuse des réactions tribochimiques des additifs phosphorés et soufrés." Thesis, Ecully, Ecole centrale de Lyon, 2012. http://www.theses.fr/2012ECDL0063.
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La maîtrise de l’additivation est l’un des enjeux majeurs de la formulation des lubrifiants, notamment pour l’industrie automobile. La formulation d’une huile est toutefois très complexe en raison du nombre important d’additifs et des nombreuses interactions possibles entre additifs, notamment entre les additifs de surface. Les phosphites organiques et les polysulfures organiques ont déjà montré leur efficacité en tant qu’additifs de surface. Toutefois malgré leur usage répandu dans les formulations des lubrifiants automobiles, peu d’études traitent des interactions pouvant avoir lieu entre ces deux types de composés. Ce travail de thèse a pour objectif la compréhension des mécanismes d’interaction (antagonisme/synergie) pouvant exister entre les phosphites organiques et les polysulfures organiques. Pour cela, une approche originale sur la lubrification par la phase gazeuse s’est avérée très pertinente. Le couplage du Tribomètre à Environnement Contrôlé (TEC) avec les systèmes d’analyses de surface XPS/Auger a permis d’analyser les tribofilms générés in situ et d’éviter ainsi toute contamination et/ou oxydation du tribofilm avant analyse. Les molécules choisies sont les additifs de lubrification industriels (polysulfures tertaires) à faibles poids moléculaires ou alors des molécules à faible poids moléculaires ayant les mêmes fonctions chimiques que les additifs usuels : trimethyl phosphite (TMPi), dimethyl phosphite (DMPi). L’étude des réactions des tribochimiques des molécules phosphorés a permis de mettre en évidence le rôle ambivalent du DMPi qui se comporte à la fois comme un phosphite pour former un phosphure de fer et comme un phosphate. Le mécanisme formation du phosphure de fer a peu être étayé par la réalisation de calculs ab initio sur l’adsorption dissociative du TMPi sur une surface de fer. Les TPS étudiés génèrent quant à eux des tribofilms à base disulfure de fer. Les mélanges binaires réalisés en phase gazeuse ont permis de mettre en évidence l’importance des rapports de concentrations des vapeurs introduites et du mode d’introduction des molécules dans le tribomètre. Les résultats obtenus en tribologie en phase gazeuse ont été corroborés par des essais complémentaires en phase liquide<br>Mastering the addivation is one of the biggest issues for the lubricants formulation, especially in the automobile industry. However automotive lubricants are very complex systems due to the numerous additives mixed with base oils. Many interactions can occur between additives, especially between surface additives. Organic phosphites and organic polysulphides have already demonstrated their effectiveness as surface additives. However, despite their widespread use in the formulations of automotive lubricants, few studies deal with the interactions taking place between these two types of compounds. The aim of this study is to understand the interactions, antagonistic or synergetic effect between these kinds of additives using Gas Phase Lubrication (GPL) approach. A Environmental Controlled Tribometer (TEC) was used as a tool to simulate the interaction between organophosphate additives and polysulfurous additives. In situ surface analysis was performed in the tribofilm formed during friction using of X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy(AES) in order to avoid any oxidation or air contamination. The molecules selected for the study can be same as the additive like the TPS molecules which are widely used as lubricant additives. Howeverto simulate the phosphite chemical function of phosphite additives, we need to select smaller molecule having the same chemical function. These molecules are dimethyl phosphite (DMPi), trimethylphosphate (TMPi) for simulating the phosphite chemical function and organic polysulphides (TPS44and TPS32). The study of the tribochemical reactions of organic phopshites allowed to clearly characterise the ambivalence of DMPi, which can react like a phosphite and induce iron phosphide formation or react like a phosphate. Ab initio numerical simulation on TMPi dissociative adsorption was carried out to identify the reactions pathways leading to iron phosphide formation. The tribochemical reaction of TPS44 on metallic iron surface leads to the formation of iron disulphidebased tribofilm. The binary vapours mixtures studied by GPL allowed to clearly identify the importance of the vapour concentration ratio between phosphite and polysulphide. Liquid phase experiments were also carried out to confirm the trend observed in GPL approach
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Semenzin, Delphine. "Réactions "d'hydrophosphoration". Etude comparée de différentes méthodes d'activation." Toulouse 3, 1994. http://www.theses.fr/1994TOU30210.
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Les sources d'activation traditionnelles sont de nature thermique, photochimique ou electrochimique. Depuis quelques annees viennent s'ajouter des methodes d'activation moins conventionnelles comme les ultrasons ou les supports solides. Au cours de ce travail, nous avons cherche a montrer ce que ces nouvelles methodes peuvent apporter dans les reactions chimiques connues pour leur difficultes (insolubilite, miscibilite, regioselectivite etc) mais aussi dans d'autres syntheses de faisabilite tout a fait convenable mais dont on peut augmenter le temps de reaction. Dans le premier chapitre, une description generale des techniques d'ultrasons et de supports solides est presentee et leur influence est illustree par des exemples de la litterature qui nous ont parus significatifs. Dans le second chapitre, une application des ultrasons a l'etude de la reactivite du phosphore elementaire est presentee. On sait que ce dernier existe sous deux formes allotropiques commerciales: le phosphore blanc et le phosphore rouge. Nous avons pu mettre en evidence grace aux ultrasons utilises en milieu basique la reactivite du phosphore rouge (forme la plus stable, la moins reactive et la moins chere) en synthetisant des phosphines variees. Une etude plus detaillee a pu montrer que la reaction se faisait a partir de la formation de la phosphine ph#3, laquelle, en milieu basique, est alkylee par une reaction de type michael. Ces resultats nous ont permis, dans le troisieme chapitre, d'etendre cette etude a l'addition de divers derives phosphores a liaison p-h sur des molecules insaturees en comparant l'effet de differentes methodes d'activation (chauffage classique et sonochimie en milieu radicalaire ou basique, photochimie et supports solides) selon la nature des reactifs utilises. Dans le dernier chapitre, les effets de l'irradiation ultrasonore ou photochimique sur certains adduits insatures obtenus sont presentes (en particulier sous l'angle de l'isomerisation cis-trans)
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Pan, Haobo. "Solubility of calcium phosphates and related oral minerals by solid titration." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39557558.
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McIntire, Mark Douglas. "Conformational studies of selected phosphines using an empirical computational approach." Virtual Press, 1985. http://liblink.bsu.edu/uhtbin/catkey/444702.
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Conformations of phenyl and alkyl substituted phosphines were studied by using an empirical computer program, CAMSEQ. The computer program employs potential energy functions for calculating non-bonded interactions. The three potential energy functions employed are: steric interactions, represented by Lennard-Jones 6-12 potentials; electrostatic interactions, computed from a Coulomb's Law function; and torsional barriers, approximated by a two-term cosine function. P-C and C-C torsional functions were parameterized for a variety of phosphorus and carbon substituents from published experimental data. Phenyl and alkyl substituent conformations as affected by length, Position and number of alkyl chain substituents are described and related to effective sizes of the phosphines.Ball State UniversityMuncie, IN 47306
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Samodien, Mugammad Ebrahim. "Analysis of enzymes involved in starch phosphate metabolism." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2633.
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Thesis (MSc (Genetics. Plant Biotechnology)) --University of Stellenbosch, 2009.<br>ENGLISH ABSTRACT: This project examined the role of proteins in starch phosphate metabolism. The first part
was aimed at the functional characterization of the SEX4, LSF1 and LSF2 genes in both
plants and bacteria. Constructs were produced to allow for expression of the three
proteins in E. coli with the SEX4 and LSF2 proteins being successfully purified and used
to produce antibodies. Immunoblot analysis indicated that the antibodies recognised the
repective proteins in extracts, but it was not clear if they actually recognised the proteins
or the GST tags they were fused to.
Virus induced gene silencing constructs were also produced to allow repression of
these three genes in Nicotiana benthamiana. This resulted in a starch excess phenotype
being observed in the leaves of silenced plants which is consistent with the known or
presumed roles for the genes. The antibodies produced were not specific enough to
confirm that the respective protein were actually repressed, but it is likely that this was
the case as plants infiltrated at the same time with a VIGS vector designed to repress
phytoene desaturase exhibited a chlorophyll bleaching phenotype. These data confirm
that SEX4 and LSF1 probable play the same role in N. benthamiana as in Arabidopsis,
and provide evidence that LSF2 is also necessary for starch degradation.
It was also attempted to characterise these proteins with respect to their substrate
utilization by setting up a glyco-array experiment. Various potato starches from
genetically modified plants were subjected to hydrolytic attack by starch degrading
enzymes and fractionated by anion exchange chromatography to produce a multitude of
glucans. These will be spotted onto glass filters and probed with the purified proteins to
see if they bind to specific starch breakdown products preferentially.
iv
The project also involved investigating the effect the SEX4 protein has on E. coli
glycogen contents. SEX4 was expressed in wild type and glgX mutant E. coli strains as it
has been shown that this stops glycogen accumulation in the wild type, but not the glgX
mutant. The cells were grown in liquid culture and glycogen contents measured. In liquid
cultures SEX4 had no effect on glycogen contents in the wild type, possible because of
problems with plasmid stability in the strain used.
This final part of the project investigated the effect that a gwd mutation has on
carbohydrate metabolism in leaves and fruits of the Micro-tom tomato cultivar. Starch
and soluble sugar contents were measured in leaves and ripening fruits. A starch excess
phenotype was found in the leaves, but no change in starch contents was determined in
either the placenta or pericarp of the fruit. Soluble sugar contents were reduced in the
fruit tissues, although the reason for this in unclear.<br>AFRIKAANSE OPSOMMING: Hierdie projek het die rol van proteine in stysel-fosfaat metabolisme ondersoek. Die
eerste deel handel oor die funksionele karaktiseering van die SEX4, LSF1 en LSF2 gene
in beide plante en bakteriee. Vektore is gekonstrueer om die uitdrukking van die drie
proteine in E.coli toe te laat terwyl die SEX4 en LSF2 proteine suksesvol gesuiwer is vir
die gebruik vir teenliggaam produksie. Immunoklad analises het getoon dat die
teenligame die spesifieke proteine in die ekstrak herken het, maar dit was nie duidelik of
dit die onderskeie proteine was of die GST-verklikker waaraan die onderskeie proteine
verbind was nie.
Virus geindiseerde geen onderdrukking konstrukte is ook geproduseer om toe te
laat vir die onderdrukking van hierdie drie gene in Nicotiana benthamiana. Dit het ‘n
stysel oorskot fenotipe tot gevolg gehad in die blare van onderdrukte plante wat konstant
is met die bekende of voorgestelde rolle van die gene. Die teenliggame wat geproduseer
is was nie spesifiek genoeg om te bewys dat die onderskeie proteine wel onderdrukis nie.
Dit kon wel die geval gewees het want plante geinfiltreer op dieselfde tyd met ‘n VIGS
vektor wat ontwerp is om phytoene desaturase te onderdruk het ‘n chlorofil bleikings
fenotipe getoon. Hierdie data bevestig dus dat SEX4 en LSF1 moontlik dieselfde rol
speel in N. benthamiana as in Arabidopsis, en toon bewyse dat LSF2 ook nodig is vir
stysel afbreek.
Karakterisasie van die onderskeie proteine met respek tot hul substraat gebruik is
ondersoek deur ‘n gliko-array eksperiment. Verskillende aartappel stysels van genetiese
gemodifiseerde plante was geonderwerp aan hydrolitiese afbreek deur stysel afbrekende
ensieme en geskei deur anioon uitruilings chromotografie om veelvuldige glukans te
vi
vervaardig. Dit is geplaas op glas filters en is ondersoek saam met die gesuiwerde
proteine om te sien of dit mag bind aan spesifieke stysel afbreek produkte.
‘n Verdere ondersoek is onderneem na die effek van die SEX4 protein op E. coli
glikogeen inhoud. SEX4 was uitgedruk in die E .coli wildetipe en glgX mutant omdat
dit reeds bewys is dat SEX4 glikogeen ophoping veroorsaak in die wildetipe maar nie in
die glgX mutant. Die selle is opgegroei in vloeibare media en glikogeen inhoud is gemeet.
In vloeibare media het SEX4 geen effek op die wildetipe se glikogeen inhoud nie wat
moontlik kan wees as gevolg van plasmied stabiliteit in die E. coli ras wat gebruik is.
Die finale deel van die projek was om die effek van ‘n gwd mutasie op koolhidraat
metabolisme in blare en vrugte van die Micro-tom tamatie kultivar te ondersoek. Stysel
en oplosbare suikers is gemeet in blare en rypwordende vrugte. ‘n Oortollige stysel
fenotipe is in die blare gevind maar geen verandering in stysel inhoud is waargeneem in
die plasenta of perikarp van die vrug nie. Oplosbare suiker inhoud het afgeneem in die
vrugweefsel dog is die rede hiervoor nie te verstane.
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梁永鏗 and Wing-hang Vitus Leung. "The calcium phosphate system in saliva-like media." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1989. http://hub.hku.hk/bib/B30425827.
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Gersdorf, Ingrid. "Spectroscopic analysis of erbium-doped silicon and ytterbium-doped indium phosphide." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2001. http://dare.uva.nl/document/60743.
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Ticconi, Carla Ann. "A genetic analysis of phosphate deficiency responses in Arabidopsis /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
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Pan, Haobo, and 潘浩波. "Solubility of calcium phosphates and related oral minerals by solid titration." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39557558.
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Carpenter, Neil Geoffrey. "Electrochemical methods for nitrate, silicate and phosphate analysis in waters." Thesis, University of Southampton, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242534.
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De, Silva-Udawatta Mihiri Nilanthi. "Functional analyses of trehalose-6-phosphate synthase in saccharomyces cerevisiae." free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9962518.
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Alagoz, Eda. "Kinetic Analysis Of Glucose-6-phosphate Branch Point In Saccharomyces Cerevisiae." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606556/index.pdf.
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Glycolysis is the main metabolic route in Saccharomyces cerevisiae and it is the sequence of enzyme catalyzed reactions that oxidatively convert glucose to pyruvic acid in the yeast cytoplasm. In addition to the basic steps, glycolysis involves branch points providing the intermediary building blocks of the cell (i.e amino acids and nucleotides). One of these pathways is glucose-6-phosphate branch point which is a junction of glycolytic pathway and pentose phosphate pathway. At this point glucose-6-phosphate can be converted to fructose-6-phosphate a metabolite of glycolytic pathway by phosphoglucoisomerase or it can be dehydrogenated to 6-phosphogluconolactone by glucose-6-phosphate dehydrogenase which is the first enzyme of the pentose phosphate pathway.
In this study, the influence of different nitrogen sources on the flux distribution through the pentose phosphate pathway and glycolysis in Saccharomyces cerevisiae was examined. For this purpose, four different compositions of nitrogen sources were used in growth media. The growth medium contained one of the following composition of nitrogen sources<br>only ammonium sulfate, only yeast nitrogen base, ammonium sulfate and histidine, yeast nitrogen base and histidine. Histidine was added because its synthesis branches from pentose phosphate pathway. In order to analyse the effect of the different compositions of nitrogen sources on the physiology of the yeast, specific activities of hexokinase, phosphoglucose isomerase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase enzymes were measured in the crude extracts of the biomass samples taken in the late exponential phase of the cultures.
Addition of histidine caused an increase in the specific activities of all the enzymes analysed in medium containing ammonium sulfate. The specific activity of hexokinase, phosphoglucose isomerase and glucose-6-phosphate dehydrogenase in medium containing yeast nitrogen base and histidine were higher than medium containing yeast nitrogen base. However, the specific activity of 6-phosphogluconate dehydrogenase decreased 3.1% in medium containing yeast nitrogen base and histidine medium with respect to medium with only yeast nitrogen base.
The OD value and dry weight in the culture containing histidine aminoacid was higher than the cultures contaning only ammonium sulfate and only yeast nitrogen base. Also the period of the exponential phase was shorter in medium containing ammonium sulfate and histidine and yeast nitrogen base and histidine than medium only ammonium sulfate and only yeast nitrogen base.
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Guo, Biwei. "Functional analysis of the Arabidopsis PHT4 family of intracellular phosphate transporters." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2662.
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Ramirez, Hernandez Rodrigo. "Synthèse et étude de complexes du palladium. Dérivés de ressources naturelles : application en catalyse." Aix-Marseille 3, 2007. http://www.theses.fr/2007AIX30053.
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Au cours de ce travail, nous avons préparé diverses molécules chirales contenant une fontion acétal. La source de chiralité a été tirée d’un produit naturel, le L-tartrate d’éthyle. Nous l’avons modifié chimiquement conduisant à des composés hétérocycliques, de structure et conformation réfléchies, basées sur la géométrie des cis-décalines et la solidité des méthylènecétals. Egalement, nous avons préparé des arylphosphonites bollaformes chiraux portant ces structures cis-décalines. Nous proposons une méthode de synthèse de nitroalcool catalysée par le palladium et, nous avons évalué l’activité énantioslélective des arylphosphonites chiraux. Egalement, nous propososn une methode de synthèse stéréosélective de phosphonates catalysée au palladium en utilissant l’oxygène de l’air comme oxydant. Finalement, nous avons préparé des complexes « mixtes » du palladium, portant un phosphonite et un deuxième ligand labile. Nous avons étudié la synthèse des palladacycles et l’activité de ces pécurseurs catalytiques palladacycles par comparaison à des systèmes catalytiques « classiques » du palladium<br>This work describes the synthesis of various chiral arylphosphonite ligands and parent palladium complexes. First, we prepared several chiral substrates having one acetal function at least. The starting material, provider of chirality, was derived from an abundant local natural product : L-diethyl tartrate. The chiral building block was submitted to synthetic sequences based on the particular conformation of cis-decalins and on the reactivity of methylene acetals, and led to specifically designed heterocyclic compounds. We also prepared several chiral bollaform phosphonites having this particular cis-decalin conformation. Then we report, on a new synthetic methodology to form nitoalcohols catalyzed by palladium complexes, under mild conditions. We studied too the stereo of chiral bollaform phosphonites and we proposed a new palladocatalyzed phosphonates synthesis using air. Finaly, we prepared several phosphonite-palladium complexes and used them in synthetic approaches to palladacycles
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Labataille, Patrick. "Synthèse et évaluation biologique d'analogues phosphonates de la 3'-azido-3'-désoxythymidine 5'-triphosphate (AZTTP) à visées antirétrovirales." Montpellier 2, 1994. http://www.theses.fr/1994MON20279.
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La synthese d'analogues phosphonates stables de la 3'-azido-3'-desoxythymidine 5'-triphosphate (azttp) ainsi que leur evaluation en tant qu'inhibiteurs de la transcriptase inverse (rt) ont ete explorees. Dans un premier chapitre, un resume des principales donnees de la litterature concernant l'azt a ete presente. Dans les deuxieme et troisieme chapitres, la synthese d'analogues de l'azttp possedant en position 5', soit une fonction ester phosphonique, soit une fonction ether a ete rapportee. Enfin, le dernier chapitre est consacre aux resultats biologiques obtenus a partir des composes synthetises. Aucun d'eux n'a fait preuve d'activite anti-vih notable ou de pouvoir inhibiteur marque de la rt
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Fabre, André. "Heterogeneite des sediments dans un reservoir a fort marnage et etude experimentale de la solubilisation du phosphore." Toulouse 3, 1988. http://www.theses.fr/1988TOU30049.
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Ben, jaber Nader. "Élaboration de revêtements prothétiques : Caractérisation physico-chimique, structurale et mécanique." Thesis, Reims, 2016. http://www.theses.fr/2016REIMS010/document.
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Ce travail présente un procédé innovant d’élaboration de revêtements prothétiques phosphocalciques : l’électrodéposition. Il porte sur la synthèse et la caractérisation de phosphates de calcium destinés au recouvrement de prothèses de hanche. Un protocole original a été développé en associant l’électrodéposition en mode courant pulsé à un traitement thermique sous atmosphère contrôlée appelé THUCA. La morphologie, la composition et la structure des revêtements obtenus ont été analysées respectivement par MEB, microanalyse X et diffraction des rayons X. Les résultats ont montré que nous obtenons un implant constitué d’un revêtement biphasique (hydroxyapatite HAP et phosphate tricalcique b-TCP) sur l’alliage de titane TA6V.Les caractérisations mécaniques par indentation, les tests de rayure (scratch test) et d’usure (tribologique) réalisées pour la première fois sur cet implant ont montré que le revêtement possède un excellent aspect cohésif et adhésif avec une excellente résistance à l’usure. Par ailleurs, la bioactivité des revêtements élaborés est évaluée en milieu physiologique en étudiant d’une part leur comportement vis-à-vis de la corrosion, et d’autre part leur comportement en milieu de culture cellulaire. L’ensemble de ces résultats indiquent que l’implant proposé possède de bonnes propriétés faisant de lui un bon candidat en tant qu’implant pour la chirurgie orthopédique.Par ailleurs, ce travail de thèse a été achevé par des études préliminaires concernant une technique complémentaire à l’électrodéposition : l’électrophorèse. Nous avons obtenu pour la première fois un revêtement constitué de nanoparticules d’hydroxyapatite ayant de bonnes propriétés mécaniques<br>This work presents an innovative process to develop prosthetic calcium phosphate coatings: electrodeposition. It focuses on the synthesis and characterization of calcium phosphates for the recovery of hip prostheses. Thus, an original protocol was developed, which combines pulsed current electrodeposition to a heat treatment method under controlled atmosphere called THUCA. Morphology, composition and structure of the coatings obtained were analyzed respectively by SEM, X-ray microanalysis and X-ray diffraction. The results showed that we obtain an implant consisting of a two-phases coating (HAP hydroxyapatite and tricalcium phosphate b-TCP) on the titanium alloy TA6V.Mechanical characterizations made by indentation, scratch tests (scratch test) and wear (tribological) for the first time on this implant showed that the coating has a good adhesive and cohesive appearance with improved wear resistance. Moreover, the bioactivity of the developed coatings was evaluated by studying their corrosion behavior in physiological medium and also their behavior in cell culture medium. All these results indicate that the proposed implant has good properties making it a good candidate as an implant for orthopedic surgery.Furthermore, this thesis was completed by preliminary studies of a complementary technique to electrodeposition: electrophoresis. We obtain for the first time a coating consisting of nano-particles of hydroxyapatite having good mechanical properties
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Garcia-Murillas, Isaac. "Functional analysis of lipid phosphate phosphohydrolases (LPP) in Drosophila melanogaster phototransduction cascade." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613148.
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Liu, Fang, and 刘方. "Time-resolved photocurrent and photoluminescence spectra of GaInP/GaAs single-junction photovoltaic devices." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2015. http://hdl.handle.net/10722/209502.
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A pulse-laser based time-resolved photocurrent (TRPC) and photoluminescence (TRPL) system with a programmable Boxcar integrator/averager system incorporated was implemented to investigate the optical properties and charge carrier dynamics in a GaInP/GaAs single-junction photovoltaic device for the purposes of understanding fundamental optoelectronic processes in the solar cell.
The implementation of whole system was realized by integrating the instrument of a Boxcar averager system with a pulse laser source + spectroscopic facilities. The delay time control and data acquisition were organized by the software code. The effects of the hardware configurations and the software parameters on the performance of the system were particularly addressed for the optimization of measurement conditions and precisions. Two main functions of TRPC and TRPL with a wide time range were demonstrated for the system.
The system was employed to measure temperature- and bias voltages-dependent TRPC and TRPL spectra of a GaInP/GaAs single-junction photovoltaic device. The spectral data show a lot of information about the transient dynamic behaviors of photogenerated charge carriers in the device, including both the rise and decay processes. Interestingly, the measured time-resolved photocurrent curves are characterized by a fast rising edge followed by a relatively slow decay process as the temperature increases. Relevant theoretical calculations and analysis to the experimental curves were also carried out to understand diffusion and transport processes of charge carriers inside the device. The results show that the variation in temperature and reverse biases results in the structural change in the space charge region of the P-N junction and therefore affects the rise and decay time constants of the time-resolved photocurrent. The TRPL spectral data give information of mid-way radiative recombination of charge carriers in the device.<br>published_or_final_version<br>Physics<br>Master<br>Master of Philosophy
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Starman, David. "Opportunities for Nutrient Recovery from Post-Digestion Sludge Handling: Analysis and Feasibility Study Using Municipal Scale Aerobic and Anaerobic Digesters." Scholar Commons, 2009. https://scholarcommons.usf.edu/etd/34.
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The wastewater treatment process has developed with the primary goals of protecting receiving water ecosystems and human health. Over time, there have been continuous innovations in process efficiencies, energy recovery, and nutrient removal. Wastewater offers opportunity for recovery of resources of various economic values, and recent research aims at process innovation to optimize resource recovery while still achieving the primary goals of the treatment process. The objective of this study is to assess the logistical and economic feasibility of recovery of nitrogen and phosphorus at two municipal treatment plants in the Tampa Bay area, one employing aerobic digestion and the other anaerobic digestion. The study is conducted using literature review of applicable processes, mass balance on the fate of nutrients (N and P) through the treatment plants and special attention to sludge handling. Based on the whole-plant mass balance conducted at the facilities, it is estimated that over 80% of the nutrient influent is routed to the solids handling side of the plant, warranting special attention to this area for nutrient recovery. Sludge digested through anaerobic and anaerobic processes have distinctly different characteristics and opportunities for resource recovery are specific to each process. Mass balances for nitrogen in the anaerobic digestion process show a high concentration of dissolved ammonia. The feasibility of struvite precipitation by addition of phosphate and magnesium compounds is evaluated through batch reaction using anaerobic sludge filtrate. Aerobic sludge contains most of the nutrient resources in the solid phase, ready for recovery if handled properly. Phosphorus release is a potential concern and specific phosphorus release rates are evaluated for a municipal scale aerobic digester.
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Moss, Rob M. "Structural studies of metal doped phosphate glasses and computational developments in diffraction analysis." Thesis, University of Kent, 2009. https://kar.kent.ac.uk/38807/.
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The thesis focuses on the analysis and determination of the structure of various metal doped phosphate glasses, which are of interest for their potential biomedical properties. The structures have been determined principally by X-ray and neutron diffraction but are also supported by complimentary X-ray absorption spectroscopy measurements and computational modelling. Such studies contribute to about half of the work presented in this thesis. Among the glasses of interest are silver-doped calcium sodium phosphates, which exhibit antimicrobial properties when the Ag+ ions are released over time in an aqueous environment. The advanced probe technique of neutron diffraction with isotropic substitution (NDIS) has been applied to elucidate the structural role of silver in these glasses. The results revealed that silver occupies a highly distorted octahedral environment analogous to that in crystalline Ag2SO4. Another glass study herein is associated with zinc titanium calcium sodium phosphate, which is biomedically interesting since the release of Zn2+ ions is shown to enhance cell attachment and proliferation. Structural analysis of multi-component glasses such as these tends to be difficult, but diffraction techniques and X-ray absorption spectroscopy have been used together to reveal the cation first neighbour coordination environments. The other significant element of the work presented here has been the development of data analysis techniques, with the emphasis on the creation of a program, which allows co-fitting of X-ray and neutron diffraction data of amorphous (and potentially crystalline) data. The code is written in MATLAB and makes use of the Nelder-Mead simplex method to minimise a set of “best guess” structural parameters supplied by the user. Extrema bound constraints are implemented by means of a sinusoidal parameter transform. Ultimately, the code is to be compiled and made available to users via the ISIS Pulsed Neutron Facility, UK.
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Kaylor, Sean C. "Development of a Low Cost Handheld Microfluidic Phosphate Colorimeter for Water Quality Analysis." DigitalCommons@CalPoly, 2009. https://digitalcommons.calpoly.edu/theses/147.
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This thesis describes the design, fabrication, and testing process for a microfluidic phosphate colorimeter utilized for water quality analysis. The device can be powered by, and interfaced for data collection with, a common cell phone or laptop to dramatically reduce costs. Unlike commercially available colorimeters, this device does not require the user to measure or mix sample and reagent. A disposable poly(dimethylsiloxane) (PDMS) microfluid chip, powered by an absorption pumping mechanism, was used to draw water samples, mix the sample at a specific ratio with a molybdovanadate reagent, and load both fluids into an onboard cuvette for colorimetric analysis. A series of capillary retention valves, channels, and diffusion pumping surfaces passively controls the microfluidic chip so that no user input is required. The microfluidic chip was fabricated using a modified SU-8 soft lithography process to produce a 1.67mm light absorbance pathlength for optimal Beer Lambert Law color absorbance. Preliminary calibration curves for the device produced from standard phosphate solutions indicate a range of detection between 5 to 30mg/L for reactive orthophosphate with a linearity of R²=91.3% and precision of 2.6ppm. The performance of the PDMS absorption driven pumping process was investigated using flow image analysis and indicates an effective pumping rate up to approximately 7µL/min to load a 36µL sample.
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Rohman, Joshua. "A Novel Trace Elemental Analysis of Potassium Phosphates." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1459243950.
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Caponera, Jay A. "Evolutionary Analysis of Duplicate Mannose-6-Phosphate Isomerase (MPI) Loci in the Blue Mussel, Mytilus edulis." Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/CaponeraJA2006.pdf.
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Schulte, Seth. "Analysis of Glucose-6-Phosphate Dehydrogenase in Malagasy Males Through Genetic Sequencing and a Population-specific Genotyping Assay." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1459352246.
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Le, Grill Sylvain. "Composite chitosane-phosphate de calcium : synthèse par atomisation séchage et caractérisation structurale." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30023/document.
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Ce mémoire porte sur l'élaboration et la caractérisation d'un matériau composite chitosane/phosphate de calcium destiné à une utilisation dans le domaine de la substitution osseuse. Le procédé d'atomisation-séchage a été choisi pour élaborer ce composite sous forme d'une poudre susceptible d'être transformée en revêtement ou objet 3D. Une étude préliminaire a permis d'appréhender les mécanismes de synthèse du phosphate de calcium, la phase minérale, par atomisation-séchage. Une suspension de particules d'hydroxyapatite stœchiométrique ou d'apatite biomimétique dispersées dans une solution acide mène systématiquement à l'apparition d'une phase amorphe. La proportion de cette phase amorphe dans la poudre atomisée-séchée est dépendante de la taille et de la cristallinité du matériau d'origine. L'atomisation séchage d'une solution acide contenant les ions précurseurs de calcium et phosphate mène à la formation d'une phase principalement amorphe. Cette poudre a pu être décrite à différentes échelles : à une échelle de l'ordre du nanomètre apparaissent des clusters, à une échelle de l'ordre de la centaine de nanomètres des agrégats sphériques de clusters organisés en chapelet tortueux et imbriqués sont identifiés et enfin à une échelle micrométrique des agglomérats de nanoparticules ont été mises en évidence. Le phosphate de calcium ainsi synthétisé possède un rapport molaire Ca/P proche de 1.3. Au-delà de ce rapport dans la solution à atomiser, de l'acétate de calcium (utilisé ici comme précurseur) recristallise dans la poudre. Pour élaborer la poudre composite, le polymère a été solubilisé et ajouté d'abord dans une suspension acide d'hydroxyapatite avant atomisation. Cette première stratégie mène à la formation d'un composite qui présente de fortes inhomogénéités de répartition des phases organiques et minérales. Pour limiter ce problème lié à la distribution de tailles de grains de la phase minérale, une seconde stratégie a été développée. Une solution de polymère contenant des précurseurs de phosphate de calcium a été préparée pour favoriser l'association à l'échelle nanométrique des deux phases. Après atomisation-séchage, un matériau composite présentant une très bonne dispersion de la phase minérale dans la matrice organique est synthétisé. La structuration de la phase minérale est modifiée par la présence du polymère. Cette modification se traduit par une diminution de la fraction volumique des clusters et, à l'échelle supérieure, la phase minérale n'est plus présente sous forme de chapelet mais en particules sphériques isolées. Par ailleurs, une interaction chimique est envisagée en raison des liaisons de type hydrogène, ioniques ou de coordinations possibles entre les deux phases. La présence du polymère inhibe également la formation de l'acétate de calcium cristallin en favorisant la formation d'un sel d'acétate de chitosane. Deux techniques de mises en forme ont été étudiées (MAPLE, pour l'élaboration de revêtements minces et l'impression 3D de pâte pour l'obtention d'objet massif) et ont permis de mettre en avant le potentiel de transformation de la poudre préparée par atomisation séchage. Les études biologiques faites sur le revêtement ont de plus permis de démontrer les propriétés antibactériennes du matériau utilisé<br>This thesis deals with the development and characterization of a chitosan/calcium phosphate composite material for use in the field of bone substitution. The spray-drying method was chosen to develop this composite in the form of a powder that could be transformed into a coating or 3D object. A preliminary study made it possible to understand the mechanisms of synthesis of calcium phosphate, the mineral phase, by spray-drying. A suspension of stoichiometric hydroxyapatite particles or biomimetic apatite dispersed in an acidic solution systematically leads to the appearance of an amorphous phase. The proportion of this amorphous phase in the spray-dried powder is dependent on the size and crystallinity of the original material. The spray drying of an acidic solution containing the precursor ions of calcium and phosphate leads to the formation of a mainly amorphous phase. This powder could be described at different scales: on a scale of about one nanometer appear clusters, on a scale of about one hundred nanometers spherical aggregates of clusters organized into tortuous and nested chaplets are identified and finally on a micrometric scale, agglomerates of nanoparticles were highlighted. The calcium phosphate thus synthesized has a molar ratio Ca/P close to 1.3. Beyond this ratio in the solution to be atomized, calcium acetate (used here as a precursor) recrystallizes in the powder. To develop the composite powder, the polymer was solubilized and added first into an acid suspension of hydroxyapatite before atomization. This first strategy leads to the formation of a composite that has strong in homogeneities in the distribution of organic and inorganic phases. To limit this problem related to the grain size distribution of the mineral phase, a second strategy has been developed. A polymer solution containing calcium phosphate precursors has been prepared to promote nanoscale association of the two phases. After spray-drying, a composite material having a very good dispersion of the mineral phase in the organic matrix is synthesized. The structuring of the mineral phase is modified by the presence of the polymer. This modification results in a reduction of the volume fraction of the clusters and, on the larger scale, the mineral phase is no longer present in the form of a string but in isolated spherical particles. Moreover, a chemical interaction is envisaged because of the hydrogen, ionic or possible coordination bonds between the two phases. The presence of the polymer also inhibits the formation of crystalline calcium acetate by promoting the formation of a salt of chitosan acetate. Two shaping techniques were studied (MAPLE, for the elaboration of thin coatings and the 3D printing of dough for obtaining massive objects) and made it possible to highlight the transformation potential of the prepared powder by spray drying. The biological studies made on the coating have also demonstrated the antibacterial properties of the material used
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O'Neill, James. "PC control of a customised calcium phosphate (CaP) sputter deposition system with plasma analysis." Thesis, University of Ulster, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.429992.
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Ntui, Clifford Manyo. "Structural and functional analysis of thiaminephosphate and homoserine kinases from Mycobacterium tuberculosis." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/63284.
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Thiamine-phosphate kinase (or ATP:thiamine-phosphate phosphotransferase, ThiL) and
homoserine (ThrB) kinases are essential to metabolism in Mycobacterium tuberculosis
(Mtb). ThiL and ThrB respectively phosphorylate thiamine monophosphate (TMP) to
thiamine diphosphate (TDP), the active form of vitamin B1, and L-homoserine to Ophosphohomoserine,
critical to aspartate biosynthesis.
In this study, ThiL and ThrB from Mtb were characterised structurally and functionally by
producing the proteins recombinantly in E. coli. Proteins were purified by affinity, anion
exchange and size exclusion chromatographies and purity checked by SDS-PAGE. ThiL and
ThrB enzyme activities were confirmed and reaction products verified by high pressure
liquid chromatography (HPLC). The crystal structure of ThiL was solved by molecular
replacement using X-ray diffraction data.
Functionally active ThiL, 36 kDa, produced hexagonal crystals belonging to space group
P6122 with one monomer per asymmetric unit. Structurally it is related to ThiL from other
organisms with minor structural deviations.
Enzymatically active ThrB, 33 kDa, was crystallised. However, crystals failed to diffract Xrays
to a suitable resolution. ThiL and ThrB could act as possible anti-TB drug targets
against Mtb.<br>Dissertation (MSc)--University of Pretoria, 2017.<br>Biochemistry<br>MSc<br>Unrestricted
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Chan, Ting-fai. "An analysis of two naturally occurring G6PD deficient mutants, G6PD Campinus and G6PD Fukaya /." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B31370172.
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Kohira, Takahiro. "Development of molecular tools for functional analyses of phosphate species in biological system." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/126490.
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Kyoto University (京都大学)<br>0048<br>新制・課程博士<br>博士(工学)<br>甲第14832号<br>工博第3129号<br>新制||工||1468(附属図書館)<br>27238<br>UT51-2009-F474<br>京都大学大学院工学研究科合成・生物化学専攻<br>(主査)教授 濵地 格, 教授 青山 安宏, 教授 白川 昌宏<br>学位規則第4条第1項該当
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Abderrahim, Mohamed Lofti. "Contribution de l'imagerie numérique à l'analyse des phosphates : application au bassin phosphate de Gafsa (Tunisie)." Saint-Etienne, 1996. http://www.theses.fr/1996STET4015.
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Les techniques orientées vers le traitement des phosphates et en particulier celles relatives à la détermination de la fraction exploitable reposent actuellement sur deux procédés : l'examen au microscope et la détermination par des méthodes analytiques : chimique, physique et physico-chimique (spectrographie, rayon x, etc. ). On identifie ainsi les phases présentes (analyse qualitative) et on effectue un ensemble de mesures (analyse quantitative), tels que taille nombre de grains, pourcentage en phase, etc. Bien qu'ils fournissent des résultats satisfaisants, les deux procédés d'analyse cités ci-dessus sont très longs. Pour améliorer le temps d'exécution des analyses et éliminer la subjectivité de l'opérateur, nous proposons, dans ce mémoire, une méthode basée sur les techniques de l'imagerie numérique. Il s'agit généralement de méthodes connues du traitement de l'image qu'il conviendrait d'adapter à la spécificité de l'instrument. Cette méthode, non destructive, permet une analyse qualitative de l'échantillon de phosphate brut en lame mince, aboutissant à la différenciation des différentes phases minérales présentes et notamment la fraction phosphatée. Cette dernière sera ensuite quantifiée en utilisant les techniques de la reconstitution dans r#3 afin d'obtenir la répartition granulométrique de l'échantillon. Les étapes nécessaires pour cette analyse des données sont de conception originale puisqu'il n'existe pas à ce jour de travaux dans le domaine des techniques des phosphates pouvant être utilisés comme référence.
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Bruening, Joseph A. "Analysis of radiation damaged and annealed gallium arsenide and indium phosphide solar cells using deep level transient spectroscopy." Thesis, Monterey, California. Naval Postgraduate School, 1993. http://hdl.handle.net/10945/26872.
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Power loss in spacecraft solar cells due to radiation damage was investigated. The mechanisms behind the degradation and based on deep-level defects in the crystalline lattice structure of the solar cell. Through a process known as Deep Transient Spectroscopy (DLTS), a correlation can be made between damage/recovery and trap energy of the cell. Gallium (GaAs/Ge) and Indium Phosphide (InP) solar cells were subjected to 1 MeV electron irradiation, to fluences of 1E16 electrons/sq cm. Attempts at recovery included thermal annealing, alone, and with an applied forward bias current, and injection annealing. Various cycles of irradiation, annealing and DLTS were performed, in an attempt to correlate damage to trap energy level and growth. The results show that DLTS cannot be performed on GaAs/Ge, and no recovery was apparent in these cells. DLTS analysis of InP indicated excellent photoinjection annealing recovery at a variety of temperatures. Lower energy level defects are associated with the recovery of the cells while the higher energy traps are indicative of permanent degradation in the Inp solar cells. Applying this information to future research could increase satellite mission life, and significantly reduce space mission costs
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Cattini, Nicola. "Phosphate regulation in Streptomyces coelicolor and Streptomyces lividans : transcriptomic analysis of phoP and Ppk mutants." Thesis, University of Surrey, 2007. http://epubs.surrey.ac.uk/843545/.
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Nutritional limitation and other stresses are known to induce the production of secondary metabolites in Streptomyces. The two-component regulatory system (PhoR/PhoP) and the enzyme polyphosphate kinase, Ppk, play an important role in adaptation of growth in conditions of phosphate limitation and mutations in both systems have been linked to increased production of antibiotics in Streptomyces lividans. To further characterize the above mentioned links phoP and ppk null mutations were generated in the prototrophic wild-type strain, MT1110, of the model streptomycete, Streptomyces coelicolor A(3)2. All strains were cultivated in 1.5 L batch fermenters using a chemically defined phosphate-limited minimal medium; metabolite and antibiotic assays were conducted alongside the transcriptomic analysis, sampling at several time points throughout cultivation. Parallel studies were performed with S. lividans TK24, a closely related streptomycete, using equivalent phoP and ppk mutant derivatives. However, the S. lividans studies were conducted with surface grown cultures, on complex R2YE medium, either phosphate limited or replete. Qualitative assessment of pigmented antibiotic production by the S. lividans mutants agreed with previous published results, with both mutants displaying enhanced pigmented antibiotic synthesis relative to the wild-type. In contrast, the S. coelicolor ppk mutant displayed significantly reduced production of pigmented antibiotics relative to the wild-type parent strain, irrespective of whether the mutant was cultivated in the minimal medium or complex R2YE medium. In the S. coelicolor experiments metabolite assays confirmed that cultures became phosphate-depleted during the batch cultivation, with the ppk mutant showing the slowest rate of depletion. From the microarray-based transcriptomic analysis, certain members of the PhoP regulon (phoR, phoP, pstS and pstC) were down-regulated in the phoP mutants, alongside ppk, consistent with their regulation by PhoP. A potential link between phosphate and nitrogen metabolism in S. coelicolor is suggested by the finding that a number of genes involved in glutamine synthesis and regulation (including glnA, glnD, glnR and glnRII) were transiently up-regulated in a phoP mutant. Furthermore, some genes involved in ATP generation (the atp operon) were also transiently up-regulated in the phoP mutant. A novel two component regulatory system (SCO4155 and SCO4156) was massively over expressed in the S. coelicolor phoP mutant, in addition to an adjacent gene, SCO4157, which encodes a homologue of the DegP/HtrA protease. A SCO4157 disruption mutant was shown to precociously hyper-produce undecylprodigiosin under phosphate limited conditions. It is speculated that the up-regulation of this system represents a PhoP-independent compensatory response to phosphate starvation. The transcriptomic analysis has enabled a greater understanding of the potential roles of PhoP and Ppk during phosphate limitation, and their involvement in antibiotic synthesis. This study has identified a large number of novel genes potentially involved in phosphate metabolism and scavenging and opens the way for a more focussed functional analysis of their respective roles.
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Chan, Ting-fai, and 陳定輝. "An analysis of two naturally: occurring G6PD deficient mutants, G6PD Campinus and G6PD Fukaya." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31370172.
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Taylor, Edward John. "Molecular analysis of the formaldehyde-fixing enzymes hexulose phosphate synthase, phospohexulose isomerase and phylogenetic analysis of the bacterium Aminomonas aminovorus C2A1." Thesis, University of Sunderland, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343883.
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Johansson, Pontus. "Returning to Vuollerim : Geoarchaeological study of Soil Samples from a Stone Age Settlement." Thesis, Umeå universitet, Miljöarkeologiska laboratoriet, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-108824.
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The Stone Age settlement site outside the village of Vuollerim in northern Sweden was first discovered in the 1980s and has been an important part of the research regarding Mesolithic and Neolithic in Norrland. One of the houses on the site was named Norpan 2 and nearly fifteen hundred soil samples were collected and stored during the excavations between 1983 and 1987. This study has focused on analysing nearly one thousand of the collected soil samples using phosphate and magnetic susceptibility analysis to further study activity on site and social structure. Furthermore, due to the large quantity of samples, a short comparison of soil sampling density was made to perceive the effect sampling density has on the interpretation of soil mapping. The results of the study indicate that the site has a large deposit of Magnetite (Fe3O4) in the soil that gives unusual MS-readings from the collected samples. The results also show a bipolar separation of finds and geoarchaeological traces within the house. This distinctive separation has been argued as an indication of dividing the space between families, but this study indicate that this separation might be due to house being divided between different activities but the evidence is not conclusive enough without further studies. The study has also shown that while a high density soil mapping gives much greater details it is still possible to gain the necessary information with fewer samples. In conclusion, it is still too early to conclude the investigations at the Vuollerim site and with the added data from this study and new information there is still more to learn from the Vuollerim site.KeywordsPhosphate analysis, Magnetic susceptibility, Vuollerim, Norpan 2, Geoarchaeology, Soil mapping
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Coleman, Jessica. "Applying Geoarchaeological Methods on an Iron Age site : Part two of a two-part study discussing Archaeological Prospection for Ytings, Gotland." Thesis, Umeå universitet, Institutionen för idé- och samhällsstudier, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-185792.
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Geoarchaeology has had a long history within archaeology around the world, but not so much so in Gotlandic archaeology. This study is aimed at drawing attention to this by using magnetic susceptibility (MS) and phosphate (P) analysis of an Iron Age site at Ytings, Gotland. This is where a small silver hoard was discovered in 1888, and in 2009 a geophysical survey was done, via metal detector, and concluded with the theory of there being a workshop in the southern field and a farmstead in the north (ArkeoDok, 2011). The first part of this study discussed predictive modeling and whether or not the information available at the time would be enough to generate a reliable model (Coleman, 2016). The first study concluded with not being able to do so since the only discrete data available was from the metal detecting survey, which when used alone is not the most reliable instrument for archaeological prospection (Coleman, 2016). This led to this current study, which is the second part of a two-part study of Ytings. This study is aimed at using geoarchaeological methods for archaeological prospection to illustrate the benefits and need for these types of studies on Gotland, by comparing the MS and P results with the 2015 excavation report.
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BOURLEGAT, FERNANDA M. LE. "Disponibilidade de metais em amostras de fosfogesso e fertilizantes fosfatados utilizados na agricultura." reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9582.
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Pinzon, Dimas Jr. "Analysis of radiation damaged and annealed gallium arsenide and indium phosphide solar cells using deep level transient spectroscopy techniques." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/25677.
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Approved for public release; distribution is unlimited<br>Degradation of solar cell performance from radiation damage was found to be reversed through annealing processes. The mechanisms behind the degradation and recovery is based on deep-level traps, or defects, in the lattice structure of the solar cell. Through a process known as Deep Level Transient Spectroscopy (DLTS) a correlation can be made between damage/recovery and trap energy level/concentration of the cell. Gallium arsenide (GaAs) and Indium phosphide (InP) solar cells were subjected to 1 MeV electron irradiation by a Dynamitron linear acceleration at two fluence levels of 1E14 and 1E15 relectrons/cm(2) The process of annealing included thermal annealing at 90 degrees C with forward bias current and thermal annealing alone (for GaAs). After each cycle, DLTS measurements were taken to determine the energy level of the traps and their concentration. Multiple cycles of irradiation, annealing and DLTS were performed to observe the correlation between degradation and recovery to trap energy level and concentration. The results show that the lower energy level traps are associated with the recovery of the cells while the higher level traps are associated with the overall permanent degradation of the cells. Applying this information to future research could allow for significant increases in satellite mission life and potentially increase mission payload.
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Nolan, Kevin C. "Multi-Staged Analysis of the Reinhardt Village Community: A Fourteenth Century Central Ohio Community in Context." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1290537990.
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Cheviet, Thomas. "Ciblage d'enzymes du métabolisme purique chez Plasmodium falciparum : Conception et étude de molécules bioactives." Thesis, Montpellier, 2019. http://www.theses.fr/2019MONTS121.
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Le paludisme, problème de santé publique mondial, est dû à plusieurs parasites possédant la caractéristique de n'avoir qu'une voie de biosynthèse nucléotidique : la voie de récupération. Dans le cadre d'une conception rationnelle d'inhibiteurs d'enzymes impliqués dans le cycle purique chez Plasmodium Falciparum (un des parasites responsable du paludisme), plusieurs composés ont donné des résultats prometteurs. Le projet de thèse sera consacré d'une part à l'optimisation structurale de ces composé-hits en interaction avec une équipe de biologistes (SAR) et une équipe de structuralistes (relation structure fonction activité), et d'autre part à la mise au point de méthodes de dosages LC/MS/MS pour identifier et étudier les cibles biologiques, et révéler l'impact des nouveaux composés sur le métabolisme purique<br>Malaria, a global public health problem, is due to several parasites which are characterized by presenting only one nucleotide biosynthesis pathway : the recovery path. As part of a rational design of inhibitors of enzymes involved in purine cycle of Plasmodium Flaciparum (one of parasites responsible for malaria), several compounds have shown promising results. This PhD project will focus firstly on the structural optimization of these hits, in interaction with a team of biologists (SAR) and of structuralists (structure-fonction-activity relationship), and secundly on the development of LC/MS/MS dosage methods to identify and study the biological targets, and reveal the impact of the omptimized compounds on the purine metabolism