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1
Singha, Rabindranath. „Chemical transformation of carbocyclic compounds and development of novel reaction protocols“. Thesis, University of North Bengal, 2021. http://ir.nbu.ac.in/handle/123456789/4348.
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Mandal, Amitava. „Transformative reactions of terpenoids and studies on their biological activity“. Thesis, University of North Bengal, 2012. http://hdl.handle.net/123456789/1571.
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Rasul, Mohammed Golam. „Phytochemical investigation of some medicinal plants transformative reaction on the isolated organic compounds and studied on their biological activities“. Thesis, University of North Bengal, 2010. http://hdl.handle.net/123456789/1370.
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4
Kaukoranta, T. (Teemu). „Patterns in reactive programming:from transformative to reactive“. Master's thesis, University of Oulu, 2015. http://urn.fi/URN:NBN:fi:oulu-201505211558.
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Functional Reactive Programming (FRP) was introduced in 1997, and it proposed the abstraction of streams of events and behaviors that nowadays are a staple in reactive programming solutions. Due to recent technological advancements, such as the Reactive Extensions library and the Elm language, and the Reactive Manifesto that was published in 2013, more and more developers are showing interest in the abstractions that reactive programming provides. When programs are divided into reactive and transformative programs, it is seen that most programs are reactive programs that depend upon external events and respond to them. Reactive programming is a paradigm that is meant to help building these kinds of programs by providing abstractions for expressing these reactions and automatically managing the flow of time and computation dependencies. There is quite a lot of research about fixing the underlying flaws of FRP, but little research has been conducted where the usage of patterns in reactive programming has been studied. In this thesis we study how some chosen patterns are changed when they are first implemented using an imperative style, and then re-implemented using a reactive style. We find that while most of our analyzed patterns work surprisingly well when using streams, there are some scenarios where the introduction of streams permeate a clear change in the pattern. During the analysis of the Model-View-Controller model, we see that streams seem to eliminate the need for ways of explicitly requesting the most up-to-date data, at least during initialization — at least during the initialization phase. Analyzing the Chain of Responsibility and the Mediator patterns revealed that using streams somewhat diminishes the value of classes that act as “mediators”. In the Mediator pattern we saw that the Mediator class was important during the initialization phase in connecting all the modules, but once they were connected the Mediator did not necessarily do anything. The Chain of Responsibility would have undergone the most drastic transformation of all the patterns. If the pattern had been implemented by using streams in a sane way, the chain aspect of the pattern would have been lost completely. Forcibly retaining the chain would have imposed a needless limitation, and would have prevented the realization of the advantages that streams may provideEnsimmäinen funktionaalista reaktiivista ohjelmointia (Funtional Reactive Programming, FRP) käsittelevä artikkeli julkaistiin vuonna 1997. Artikkeli esitteli ensimmäisenä abstraktiot tapahtumille (events) sekä käytöksille (behaviours), jotka ovat nykyään tärkeä osa lähes jokaista reaktiivisen ohjelmoinnin kirjastoa tai kieltä. Reaktiivinen ohjelmointi on viime vuosina kasvattanut suosiotaan — tähän ovat vaikuttaneet esimerkiksi uudet teknologiat, kuten Reactive Extensions -kirjasto ja Elm-ohjelmointikieli, sekä 2013 julkaistu Reactive Manifesto. Kun ohjelmat jaetaan kahteen kategoriaan, transformativiisin ja reaktiivisiin, huomataan että suurin osa ohjelmista on reaktiivisia. Reaktiiviset ohjelmat ovat ohjelmia, jotka riippuvat ulkoisista syötteistä ja vastaavat niihin. Reaktiivinen ohjelmointiparadigma auttaa tällaisten ohjelmien rakentamisessa antamalla ohjelmoijan käyttöön tehokkaita abstraktioita näiden reaktioiden ilmaisemiseen, sekä automaattisesti valvomalla ajankulkua ja laskennallisia riippuvuuksia. Funktionaalista reaktiivista ohjelmointia on tutkittu paljon, mutta iso osa tästä tutkimuksesta keskittyy korjaamaan kyseisen paradigman puutteita. Tässä tutkielmassa tutkimme miten tietyt valitut suunnittelumallit muuttuvat kun ne ensin toteutetaan perinteisellä, imperatiivisella tyylillä, ja sen jälkeen toteutetaan uudelleen reaktiviisella tyylillä. Toteamme, että reaktiivinen ohjelmointitapa toimii hyvin suurimmassa osassa tutkimistamme suunnittelumalleista, mutta löydämme silti tapauksia, jolloin uusi ohjelmointityyli aiheuttaa mallissa selkeitä muutoksia — hyviä tai huonoja. Model-View-Controller (MVC) mallia analysoitaessa huomattiin, että reaktiivinen ohjelmointityyli poistaa osittain tarpeen eksplisiittesti pyytää päivitettyä versiota käytettävästä datasta — uusin data on aina automaattisesti saatavilla kuuntelemalla (subscribe) tietovuota (stream). Analysoitaessa Chain of Responsibility ja Mediator-suunnittelumalleja huomattiin, että välikätenä toimivien luokkien merkitys heikkenee reaktiivisessa ohjelmoinnissa. Mediator-mallissa Mediator-luokan rooli oli oleellinen alustusvaiheessa, mutta kun muut luokat oli saatu yhdistettyä, kyseisen luokan ei ajovaiheessa tarvinnut välttämättä tehdä mitään. Chain of Responsibility-mallia ei päädytty toteuttamaan, sillä mallin toteuttaminen vaatisi, että joko mallille oleellista ketjua ei toteutettaisi sen alkuperäisessä muodossa, tai että käytössä olevia abstraktioita käytettäisiin huomattavan tehottomasti
5
Sinha, Rajendra Prasad. „Studies on some transformative reactions of triterpenoids“. Thesis, University of North Bengal, 1993. http://hdl.handle.net/123456789/816.
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6
Pariyar, Gyan Chandra. „Explorative studies on carbon hetero bond transformation reaction and carbon-hetero bond formation reaction“. Thesis, University of North Bengal, 2018. http://ir.nbu.ac.in/handle/123456789/2813.
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Mothay, jyotsna. „Studies on the transformative reactions of carbocyclic compounds“. Thesis, University of North Bengal, 2002. http://hdl.handle.net/123456789/771.
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8
Amass, Dorothy Gwendoline. „Block co-polymerization by transformation reactions“. Thesis, Aston University, 1996. http://publications.aston.ac.uk/9679/.
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The aim of this study was to use the transformation of anionic to metathesis polymerization to produce block co-polymers of styrene-b-pentenylene using WC16/PStLi and WC16/PStLi/AlEtC12 catalyst systems. Analysis of the products using SEC and 1H and 13C NMR spectroscopy enabled mechanisms for metathesis initiation reactions to be proposed. The initial work involved preparation of the constituent homo-polymers. Solutions of polystyryllithium in cyclohexane were prepared and diluted so that the [PStLi]o < 2x10-3M. The dilution produced initial rapid decay of the active species, followed by slower spontaneous decay within a period of days. This was investigated using UV/visible spectrophotometry and the wavelength of maximum absorbance of the PStLi was found to change with the decay from an initial value of 328mn. to λmax of approximately 340nm. after 4-7 days. SEC analysis of solutions of polystyrene, using RI and UV/visible (set at 254nm.) detectors; showed the UV:RI peak area was constant for a range of polystyrene samples of different moleculor weight. Samples of polypentenylene were prepared and analysed using SEC. Unexpectedly the solutions showed an absorbance at 254nm. which had to be considered when this technique was used subsequently to analyse polymer samples to determine their styrene/pentenylene co-polymer composition. Cyclohexane was found to be a poor solvent for these ring-opening metathesis polymerizations of cyclopentene. Attempts to produce styrene-b-pentenylene block co-polymers, using a range of co-catalyst systems, were generally unsuccessful as the products were shown to be mainly homopolymers. The character of the polymers did suggest that several catalytic species are present in these systems and mechanisms have been suggested for the formation of initiating carbenes. Evidence of some low molecular weight product with co-polymer character has been obtained. Further investigation indicated that this is most likely to be ABA block copolymer, which led to a mechanism being proposed for the termination of the polymerization.
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Patel, A. V. „Microbial transformation of spirostanes and related compounds“. Thesis, University of Portsmouth, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375659.
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10
Matthews, Rosalyn D. „Transformation and decolorization of reactive phthalocyanine“. Diss., Available online, Georgia Institute of Technology, 2004:, 2003. http://etd.gatech.edu/theses/available/etd-04062004-164728/unrestricted/matthews%5Frosalyn%5Fd%5F200312%5Fphd.pdf.
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Thesis (Ph. D.)--School of Civil and Environmental Engineering, Georgia Institute of Technology, 2004. Directed by Spyros G. Pavlostathis.Vita. Includes bibliographical references (leaves 381-393).
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Clarke, P. D. „Transformation and addition reactions in the chromone series“. Thesis, University of Salford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372132.
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Doohan, Fiona Maria. „Molecular techniques for studing Fusarium ear blight of wheat“. Thesis, Open University, 1997. http://oro.open.ac.uk/57682/.
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This work has compared polymerase chain reaction (PCR) assays and traditional visual disease assessment to evaluate the severity of Fusarium ear blight (FEB) ofwheat under field and glasshouse conditions. In a field trial, PCR analysis highlighted the problem of diagnosis of FEB of wheat based on visual disease assessment where natural inoculum was present. PCR-based analysis detected F. poae predominantly in the glumes and Microdochium nivale sub-species were predominantly found in the rachis component of ears. M nivale var. majus was more frequently observed than var. nivale (64 and 36 %, respectively). Quantitative PCR analysis and conventional visual disease assessment were used to evaluate fungicide efficacy against FEB of wheat caused by F. culmorum and F. poae in three glasshouse trials (1994/5-1996/7). Prochloraz and tebuconazole significantly decreased both visual symptoms of FEB and fungal DNA content of F. culmorum and F. poae ear blight of wheat. Overall, both fungicides appeared equally effective, although the efficacy ofthese fungicides was consistently greater as measured by PCR analysis rather than by visual disease assessment. Inoculation with F. culmorum significantly reduced yield (1000 grain weight) whereas inoculation with F. poae had no significant effect on yield. Fusarium culmorum was successfully transformed with the GUS reporter gene. GUS activity levels of transformants varied, but transformation did not affect pathogenicity on wheat seedlings. A GUS transformant was used to study the effectiveness of two fungicides against F. culmorum foot rot of wheat. Primers to the Tri5 gene were used to develop a PCR-based assay for the specific detection ofpotential trichothecene-producing Fusarium species. These primers were also used to develop an RT-PCR-based assay for the detection and semiquantification of F. culmorum Tri5 gene expression 'relative to p-tubulin gene expression' in RNA extracts from F. culmorum. This assay was used to show that time and fungicides can affect Tri5 gene expression in liquid culture.
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Marfil, Vega Ruth. „Abiotic Transformation of Estrogens in Wastewater“. University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1289235973.
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Yan, Zifei. „Equivalence Transformations for a System of a Biological Reaction Diffusion Model“. Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2201.
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A biological reaction diusion model has gained much attention recently. This model is formulated as a system of nonlinear partial dierential equations that contains an unknown function of one dependent variable. How to determine this unknown function is complicated but also useful. This model is considered in this master thesis. The generators of the equivalence groups and invariant solutions are calculated.
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Singha, Rabindranath. „Chemical transformation of carbocyclic compounds and development of novel reaction protocols“. Thesis, University of North Bengal, 2021. http://ir.nbu.ac.in/handle/123456789/4326.
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16
Kanno, Hisashi. „In situ alcohol oxidation-transformation reactions using manganese dioxide“. Thesis, University of York, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270357.
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17
Smith, Donna Lee. „Development of novel metal-catalysed methods for the transformation of Ynamides“. Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8895.
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I. Rhodium-Catalysed Carbometalation of Ynamides using Organoboron Reagents. As an expansion of existing procedures for the carbometalation of ynamides, it was discovered that [Rh(cod)(MeCN)2]BF4 successfully promotes the carbometalation of ynamides with organoboron reagents. A variety of organoboron reagents were found to be suitable for this reaction, but mostly the use of arylboronic acids was explored. The developed methodology provides β,β-disubstituted enamide products in a regio- and stereocontrolled manner. II. Palladium-Catalysed Hydroacyloxylation of Ynamides. In the presence of palladium(II) acetate, ynamides successfully underwent a hydroacyloxylation reaction with a variety of carboxylic acids. This carboxylic acid addition occurred highly regio- and stereoselectively to provide α-acyloxyenamides. Applications of the α-acyloxyenamide products were also investigated. III. Rhodium-Catalysed [2+2] Cycloaddition of Ynamides with Nitroalkenes. A novel rhodium catalyst system has been developed in order to promote the [2+2] cycloaddition reaction between ynamides and nitroalkenes. The reaction provides cyclobutenamide products and was diastereoselective in favour of the trans cyclobutenamide. Both the ynamide scope and the nitroalkene scope of the reaction have been explored.
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Zhang, Junlong, und 張俊龍. „Macromolecular ruthenium porphyrin catalysts for organic transformation reactions: mechanistic andcatalytic studies“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31545725.
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LIN, PENG. „Enzyme cascade reactions on 3D DNA scaffold with dynamic shape transformation“. Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/265209.
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京都大学新制・課程博士
博士(エネルギー科学)
甲第23437号
エネ博第424号
新制||エネ||81(附属図書館)
京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻
(主査)教授 森井 孝, 教授 佐川 尚, 教授 片平 正人
学位規則第4条第1項該当
Doctor of Energy Science
Kyoto University
DFAM
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Sakurai, Shunya. „Development of Transformation Reactions with Alkylsilyl Peroxidesas Alkyl Radical Precursors under Cu Catalysis“. Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263490.
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21
Shirsath, Sachin R. „Exploring new synthesis transformations employing p-quinone methides as versatile acceptors in 1,6-addition reactions“. Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2022. https://hdl.handle.net/20.500.12252/6219.
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22
Cakir, Esen. „Synthesis Of Novel Chiral N,n-dialkyl Substituted 1,4-amino Alcohols And Applications In Asymmetric Transformation Reactions“. Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608484/index.pdf.
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Amino alcohols are valuable bioactive substances and frequently used as chiral catalyst in various asymmetric transformation reactions. In the synthetic route, the asymmetric synthesis of novel chiral N,N-dialkyl substituted chiral 1,4-amino alcohols are performed starting with meso-anhydride 38. Quinine-mediated desymmetrization of the anhydride with methanol afforded (2S,3R)-cis-monoester 39 with a high enantiomeric excess (up to 98% ee). Chemoselective amidation of hemiester with various N,N-dialkyl substituted amines resulted in amido esters and they were subjected to LAH reduction to afford chiral 1,4-amino alcohol ligands.
The activities of the chiral ligands, (2S,3R)-43, (2S,3R)-44, (2S,3R)-45, (2S,3R)-46 were tested in various asymmetric transformation reactions, i.e. asymmetric diethylzinc addition and asymmetric Diels-Alder reactions.
Keywords: 1,4-Amino alcohols, chiral ligand, asymmetric diethylzinc addition reaction, Diels-Alder reaction
23
Poupart-Lafarge, Henri. „Reaction and transformation of airlines in a deregulated environment : a strategy for Air France“. Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/34085.
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Prabhu, Anil K. „Catalytic Transformation of Greenhouse Gases in a Membrane Reactor“. Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/26430.
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Supported Ni and Rh catalysts were developed for the reforming of two greenhouse gases, methane and carbon dioxide to syngas (a mixture of hydrogen and carbon monoxide). This is an endothermic, equilibrium limited reaction. To overcome the thermodynamic limitations, a commercially available porous membrane (Vycor glass) was used in a combined reactor-separator configuration. This was to selectively remove one or more of the products from the reaction chamber, and consequently shift the equilibrium to the right. However, the separation mechanism in this membrane involved Knudsen diffusion, which provided only partial separations. Consequently, there was some transport of reactants across the membrane and this led to only marginal improvements in performance. To overcome this limitation, a new membrane was developed by modifying the Vycor substrate by the chemical vapor deposition of a silica precursor. This new membrane, termed Nanosil, provided high selectivity to hydrogen at permeabilities comparable to the support material. Application of this membrane in the combined reactor-separator unit provided higher conversions than that obtained using the Vycor membrane.Ph. D.
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Zhang, Junlong. „Macromolecular ruthenium porphyrin catalysts for organic transformation reactions mechanistic and catalytic studies /“. Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B31545725.
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Onike, F. N. „Time-temperature-transformation (TTT) curves for and the thermal decompsition reactions of kaolinite, montmorillonite and two muscovite samples“. Thesis, University of Hull, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.377390.
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27
Yeh, Xian-Li Johnson W. L. „Reaction of hydrogen with crystalline and amorphous alloys : crystal to amorphous transformation induced by hydrogen /“. Diss., Pasadena, Calif. : California Institute of Technology, 1987. http://resolver.caltech.edu/CaltechETD:etd-03042008-144844.
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28
Gonzalez, Richard. „Biocatalytic transformation of steroids using solvent-enhanced Beauveria bassiana“. Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/1610.
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This dissertation describes efforts to improve the oxidative capacity of n-alkane- induced Beauveria bassiana; a fungus and a versatile whole cell biocatalyst used in the biotransformation of steroids. n-Hexadecane was used as the carbon source during the growth of B. bassiana, presumably to induce the expression of oxidative enzymes, thus enhancing the oxidation of unactivated carbons. Dehydroepiandrosterone (DHEA) is an essential endogenous male-hormone and serves as a metabolic intermediate in the production of more potent androgens. Using DHEA as a substrate also provides the opportunity to study the hydroxylation of an unfunctionalized carbon, an attractive reaction that produces valuable intermediates for chemical synthesis. Results showed that exposing and inducing cells in n-hexadecane improves the synthesis of 11α-hydroxy derivatives. Reactions were carried out with cells grown on n-hexadecane, resulting in 65 ± 6.3 % conversion of DHEA to androstenediol (40.3% mM) and 3β,11∝,17β- trihydroxyandrost-5-ene (22.8% mM), as determined by HPLC, NMR and LCMS analyses. However, experiments with non-induced cells resulted in a poor substrate conversion (17%). To extend use of B. bassiana to pharmaceutical applications, it was necessary to optimize reaction conditions such as biocatalyst preparation, substrate concentration, agitation reaction temperature and pH. Higher substrate conversion, selectivity and yield of desired product were achieved with the reactor arrangement of “Resting Cells”. The apparent rate of reaction fits a Michaelis-Menten kinetic model with a maximum reaction rate of 4.45 mM/day, revealing that the transformation of intermediate androstenediol to desired 3β,11∝,17β-trihydroxyandrost-5-ene is the limiting step in the reaction. Interestingly, when a diluted amount of substrate was used, a higher yield of 11∞-hydroxy steroid was achieved. Also, reactions at 26°C with pH ranges between 6.0 and 7.0, resulted in the highest conversion (70%) and the higher product yield (45.8%). The maximum conversion of DHEA (71%) was achieved in experiments with high biomass loading, and the increment of desired product yield (11∝-hydroxy) was directly proportional to the amount of biomass used. Moreover, a high VMax/KM value was achieved with high biomass yields. Interestingly, the changes in biomass yield did not have a considerable effect on reaction selectivity. The main drawbacks of biocatalysis for production of steroids were addressed and approaches to minimize the drawbacks have been presented. The production of desired product (11∝-DHEA) was significantly improved using cells previously adapted to n-hexadecane.
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GUSMAO, DA SILVA JORGE. „Transformation catalytique des huiles vegetales en gazole : mecanisme et optimisation des reactions d'hydrocraquage“. Paris 6, 1986. http://www.theses.fr/1986PA066405.
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Etude experimentale des reactions d'hydrocrackage d'une huile vegetale en autoclave, sous pression d'hydrogene, entre 623 et 708**(o)k, en presence de catalyseurs hydrogenants. On a mis en evidence les sequences detaillees des reactions qui transforment les composes insatures et les triglycerides en hydrocarbures du type "gazole". Le deplacement de l'equilibre global vers la formation d'hydrocarbures a ete realise pour une pression finale d'hydrogene de 200 bars. Un taux de conversion proche de 100% molaire a ete obtenu pour deux huiles vegetales a 633**(o)k, avec des catalyseurs ni-mo/gamma -al::(2)o::(3) et ni-mo/sio::(2)-al::(2)o::(3) sulfures
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Grigorieva, Raisa. „Etude des transformations de phases dans le revêtement Al-Si lors d'un recuit d'austénitisation“. Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL019N/document.
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De nos jours on utilise de plus en plus les aciers pré-revêtus dédiés aux applications pour emboutissage à chaud afin de protéger la surface de l’acier contre la décarburation et l’oxydation durant le traitement thermique. Le revêtement est déposé à chaud en continu par immersion de la bande d’acier dans un bain d’Al-Si. Pendant l’austénitisation le revêtement Al-Si se transforme par réactions d’inter-diffusion et de solidification. Ces réactions conditionnent la microstructure finale et en particulier la surface du revêtement, responsable des propriétés d’emploi telles que le soudage par point et l’adhérence peinture.A l’état de livraison le revêtement Al-Si contient les phases suivantes : des grains d’Al, l’eutectique ternaire Al-Fe-Si, une couche intermétallique ternaire Al-Fe-Si et une couche intermétallique binaire Al-Fe. Après austénitisation les phases se transforment en deux types d’intermétalliques : intermétalliques ternaires riches en Si et intermétalliques binaires pauvre en Si.Durant cette étude une identification complète des différentes phases a été établie. Les phases initialement riches en Si se transforment en phases fusibles par réactions eutectique ou péritectique. La présence de phase liquide accélère la diffusion locale de fer permettant aux phases riches en Si de garder leur contenu en Si pendant tout le traitement thermique. C’est la diffusion du fer qui stabilise les gradients en Si dans le revêtement, malgré les lois de diffusion classiques. En utilisant le diagramme de phases ternaire il a été démontré comment l’enrichissement en fer s’établit dans le revêtement tout en gardant l’équilibre aux interfaces entre les phases riches et pauvres en SiNowadays more and more pre-coated steels are applied in hot-stamping process to prevent the steel surface against iron oxidation and decarburization during the heat-treatment. The coating is deposited by hot-dipping the coil in an Al-Si bath. During the austenitization, the Al-Si coating transforms completely by inter-diffusion and solidification reactions, which define the final microstructure and particularly the top layer responsible for the in-use properties like spot welding and painting adhesion.At the delivery state, the Al-Si coating is a multiphase coating containing the following phases: Al-grains, Al-Fe-Si ternary eutectic phase, an Al-Fe-Si intermetallic layer and a binary Al-Fe interfacial layer. After the heat-treatment, all the phases transform into two types of intermetallic compounds: Si-rich ternary and Si-poor binary compounds.During this study, a complete identification of the different intermetallic phases has been conducted. Initial ternary Al-Fe-Si phases transform into fusible phases by eutectic or peritectic reaction. The presence of liquid state enables rapid local iron diffusion which allows to the Si-rich phases to keep their high Si content during the whole treatment. So the iron diffusion stabilizes the Si gradients in the coating despite the classical diffusion laws. Using the ternary phase diagram it was shown how iron enrichment in the coating proceeds by keeping thermodynamical equilibrium along the interfaces between Si-rich ternary and Si-poor binary phases. A phenomenological model of phase transformations explaining the formation of differente coating microstructures during the austenitization step is proposed
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Moscu, Corcodel Alina. „Structural transformation under reaction conditions of supported PtSn nanoparticles characterized by in situ DRIFTS and kinetic modeling“. Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10177.
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La réaction d’oxydation sélective du CO par O2 en présence d’un excès d’hydrogène (PROX) est considérée comme une étape de purification essentielle de l’H2 à utiliser dans des piles à combustible. L’objectif de cette thèse est de mieux comprendre le mécanisme de cette réaction sur des catalyseurs bimétallique s à base de Pt et Sn. Des catalyseurs modèles Pt et Pt-Sn ont été synthétisés en deux étapes : (i) formation de nanoparticules (NP) métalliques colloïdales en suspension suivi par ( ii) l’imprégnation de ces particules sur des supports. L’adsorption du CO suivit par spectroscopie FT-IR en réflexion diffuse (DRIFTS) a été utilisée pour caractériser ces solides après une réduction permettant de reformer des phases d’alliage PtSn. L’analyse DRIFTS permet de caractériser la nature des sites de Pt présents, soit dans l’alliage, soit dans des phases pures de Pt. La chaleur d’adsorption du CO sur la phase d’alliage a été mesurée par DRIFTS, pour la première fois, et apparait bien plus faible que celle sur le Pt seul. De manière surprenante, la ségrégation de l’alliage en présence de CO/H 2 à des températures inférieur es à 175°C a été mise en évidence. Des mesures in situ DRIFTS de la réaction d’oxydation préférentielle du CO (PROX) indiquent que l’alliage se transforme rapidement en Pt et SnOx de par la présence de l’O2. Aucune indication de la présence d’alliage n’a jamais pu être obtenue sous PROX, indiquant que les meilleures propriétés catalytiques associés aux phases Pt-Sn sont dues à leur habilité à générer une nouvelle phase active Pt+SnOx lors de leur ségrégation. Un modèle microcinétique du PROX sur Pt+SnOx a été développé sur la base de ceux pertinents à l’oxydation du CO et PROX sur Pt seul, permettant une modélisation satisfaisante des données. Ce travail montre l’intérêt du couplage des méthodes spectroscopiques et cinétiques pour la compréhension de la structure des catalyseurs « au travail » et des mécanismes de réactions complexesThe selective oxidation of CO in the presence of a large excess of H2 (PROX) is considered as a crucial step in the purification of H 2 to be used in low-temperature fuel cells, which are clean sources of energy. The objective of this thesis was to better understand the reaction mechanisms taking place over promising catalysts based on Pt and Sn. Model Pt-Sn catalysts were prepared by a two-step method: (i) synthesis of metallic nanoparticules (NP) in a colloidal suspension followed by (ii) the deposition of these NPs onto a support. The first step of the method enabled to produce well-controlled Pt-Sn NPs in terms of size and composition. However, the NPs were partly destroyed during the deposition step followed by calcination, due to the reoxidation of Sn. The adsorption of CO followed by diffuse reflectance spectroscopy (DRIFTS) was used to characterize the nature of these solids following a reduction, which was able to regenerate an alloyed phase. The DRIFTS analysis enabled to discriminate between Pt in an alloyed phase and Pt on monometallic surfaces. The heat of CO adsorption measured by DRIFTS appeared to be much lower than that associated with the pure Pt phase. Surprinsingly, a segregation of Pt and Sn was observed under a CO/H2 mixture below 175°C. In situ analysis by DRIFTS of the PROX reaction indicated that the Pt-Sn alloy rapidly decomposed in the presence of O2, forming an intimate mixture of Pt and SnOx. No evidence of the presence of Pt -Sn alloyed phases could be obtained under PROX conditions, suggesting that the superior catalytic activity of the Pt –Sn materials were related to the Pt+SnOx mixture. A detailed PROX microkinetic model was developed over Pt+SnOx, based on those relevant to CO oxidation and PROX over pure Pt. This work epitomises the benefits in combining in situ spectroscopic study with kinetic modelling to better understand the structure of catalysts “at work” and reaction mechanisms
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Vo, Hao T. H., und Hao T. H. Vo. „Transformation of Trace Organic Contaminants Involving Reactive Oxygen Species Driven By Solar Lights“. Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/626333.
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The presence of trace organic compounds (TOrCs) in wastewater effluent and surface waters has raised attention due to their health and environmental effects. Some TOrCs are naturally attenuated via biodegradation, photo-degradation and/or adsorption, but some persist in the environment as contaminants in surface and ground waters. Thus, it is crucially important to understand their transformation pathways and their mechanisms following their discharge into the environment. This work presents research in three parts:
• The first part represents an investigation of photo-transformation of TOrCs (e.g., furfuryl alcohol, p-cresol, gemfibrozil) under UV254, UVA and natural sunlight, and involving reactive oxygen species including singlet oxygen, hydroxyl radicals, triplet excited states, and specific inorganic radicals that are created by effluent organic matter (EfOM). Singlet oxygen was the only ROS, generated from effluent organic matter (EfOM) that mainly contributed to the photo-transformation of these selected TOrCs. A comprehensive mechanism and complementary kinetic model were proposed to predict the trajectories of TOrC removals via reaction with singlet oxygen. Simulations built on predicted quantum efficiencies accounted for light shading and competitive effects. Agreement between measurements and simulations was excellent.
• The second part of the dissertation summarizes expected removal efficiencies for fifty-five TOrCs in alternative engineered and natural treatment processes including conventional biological treatment, advanced oxidation processes (AOP), reverse osmosis (RO), granular activated carbon (GAC), and sunlight photolysis.
• The last section of the dissertation follows the trajectories of a series of TOrCs and total estrogenic activity in the Santa Cruz River, following their discharge from a wastewater treatment plant in the Tucson area. The study suggests that some TOrCs tend to persist in the environment while others experience photo (or other) transformations that diminish their concentrations or activities with distance and time of travel in the river. The attenuation of estrogenic activity was dependent on sunlight and the presence of specific (unidentified) wastewater components.
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Jang, Eunseon. „Reactive transport simulation of contaminant fate and redox transformation in heterogeneous aquifer systems“. Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-226811.
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The transport of contaminants in groundwater system is strongly influenced by various aquifer heterogeneity factors such as spatial aquifer heterogeneity of hydraulic conductivity and reactive substances distribution. The contaminants transport can be simulated by using numerical reactive transport models, and their fate can be possibly even predicted. Furthermore, reactive transport modeling is an essential tool to get a profound understanding of hydrological-geochemical complex processes and to make plausible predictions of assessment.
The goal of this work is to improve our understanding of the groundwater contaminants fate and transport processes in heterogeneous aquifer systems, with a focus on nitrate problems. A large body of knowledge of the fate and transport of nitrogen species has been achieved by previous works, however, most previous models typically neglect the interrelation of physical and chemical aquifer heterogeneities on the contaminant fate and redox transformation, which is required for predicting the movement and behavior of nitrate and quantifying the impact of uncertainty of numerical groundwater simulation, and which motivates this study. The main research questions which are answered in this work are how aquifer heterogeneity influences on the nitrate fate and transport and then, what is the most influential aquifer heterogeneity factor must be considered. Among the various type of aquifer heterogeneity, physical and chemical aquifer heterogeneities are considered.
The first part of the work describes groundwater flow system and hydrochemical characteristics of the study area (Hessian Ried, Germany). Especially, data analyses are performed with the hydrochemical data to identify the major driving force for nitrate reduction in the study area. The second part of the work introduces a kinetic model describing nitrate removal by using numerical simulation. The resulting model reproduces nitrate reduction processes and captures the sequence of redox reactions. The third and fourth parts show the influence of physical and chemical aquifer heterogeneity with varying variance, correlation length scale, and anisotropy ratio. Heterogeneous aquifer systems are realized by using stochastic approach. Results, in short, show that the most influential aquifer heterogeneity factors could change over time. With abundant requisite electron donors, physical aquifer heterogeneity significantly influences the nitrate reduction while chemical aquifer heterogeneity plays a minor role. Increasing the spatial variability of the hydraulic conductivity increases the nitrate removal efficiency of the system in addition. If these conditions are reversed, nitrate removal efficiency varies by the spatial heterogeneity of the available initial electron donor. The results indicate that an appropriate characterization of the physical and chemical properties can be of significant importance to predict redox contamination transport and design long-term remediation strategies and risk assessment.
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Siesjö, Peter. „Immunotherapy of rat brain tumors with mutagen induced, cross-reactive tumor cell variants“. Lund : Section of Tumor Immunology, Dept. of Cell and Molecular Biology, University of Lund, 1997. http://books.google.com/books?id=TXZrAAAAMAAJ.
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Renou, Jean-Pierre. „Transformation génétique du chrysanthème (dendranthema grandiflora tzvelev) par agrobacterium“. Angers, 1992. http://www.theses.fr/1992ANGE0009.
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La possibilité de transformation génétique du chrysanthème par agrobacterium a été étudiée. Des racines transformées ont pu être obtenues après inoculation avec a. Rhizogenes. Cependant la régénération de plantes transformées ne fut possible que dans de rares cas, après des temps de culture in vitro très longs. Des plantes transformées furent ensuite obtenues grâce à la souche d'agrobacterium. Eha 101 contenant un plasmide vecteur binaire qui comporte les gènes : npt ii, hpt et gus. Ces plantes ont été obtenues par sélection sur la résistance à la kanamycine. Différents protocoles ont conduit à l'obtention de plantes transformées, mais les conditions optimales furent l'inoculation de nuds immédiatement transférés sur un milieu sélectif contenant du cefotaxime. La transformation de plantes gus positives a été confirmée par hybridation moléculaire de l'ADN et amplification génique. Des plasmides vecteurs binaires contenant des gènes d'intérêt agronomiques ont été construits : les gènes rol a, b et c du ri tl-dna afin d'étudier leur effet sur le port de la plante, et le gène de la dihydroflavonol réductase de l'antirrhinum majus afin de permettre une modification de la couleur des fleurs de chrysanthème.
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Adenot, Aurélien. „Activation et transformation catalytique de SO₂ par des composés organométalliques et organiques“. Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASF014.
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Produit notamment lors de la combustion de ressources fossiles carbonées contenant des impuretés soufrées, le dioxyde de soufre (SO₂) est l’un des polluants majeurs de notre atmosphère. Toxique à la fois pour l’homme et pour l’environnement, sa conversion représente donc un enjeu majeur. De fait, son utilisation en tant que source de soufre pour la chimie fine revêt un triple intérêt : économique, sanitaire et écologique. Dans cette optique, nous nous sommes intéressés à la formation de sulfones à partir de SO₂, et ce grâce à l’usage de catalyseurs métalliques et d’organosilanes, composés nucléophiles doux, non toxiques et peu coûteux. Nous avons également étudié l’interaction entre le SO₂ et des paires de Lewis frustrées, ouvrant la voie à des réactions organocatalysées de valorisation du SO₂. Le développement de tels processus nécessite une compréhension détaillée de la réactivité du SO₂ et des mécanismes réactionnels d’activation et de transformation de ce gaz. Ainsi, une attention particulière a été apportée à l’étude du fonctionnement de ces réactionsNotably produced during the combustion of fossil carbon resources including sulfur impurities, sulfur dioxide (SO₂) is one of the major pollutants in our atmosphere. Toxic for both humans and the environment, its conversion represents thus a major challenge. Indeed, its use as a source of sulfur for fine chemicals offers a triple benefit : economic, health and ecological. With this in mind, we took an interest in the formation of sulfones from SO₂, through the use of metallic catalysts and organosilanes, which are mild, non-toxic and inexpensive nucleophilic compounds. We also studied the interaction between SO₂ and frustrated Lewis pairs paving the way for organocatalyzed SO₂ value-adding reactions. The development of such processes requires a detailed understanding of SO₂ reactivity and of mechanisms of activation and transformation of this gas. Therefore, a particular attention has been paid to the study of these reactions operating modes
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Dussol, Damien. „Étude expérimentale et modélisation cinétique de la transformation d’éthanol en butadiène“. Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1221/document.
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Le butadiène est une molécule d’intérêt industriel qui peut être produite par le procédé dit Ostromislensky, avec l’éthanol en tant que matière première. Cette étude a pour objectif de développer un modèle cinétique pour expliquer la transformation d’un mélange éthanol/acétaldéhyde en butadiène, dans le cadre de la seconde étape de ce procédé. Le modèle cinétique est basé sur un schéma réactionnel et un modèle de réacteur. Le schéma proposé comprend la voie de Gorin Jones, communément acceptée dans la littérature, et une toute nouvelle voie impliquant un intermédiaire buténone. Les étapes clés ont été étudiées spécifiquement via des tests dédiés. Le schéma décrit aussi les étapes amenant aux principaux produits secondaires. Il a été validé à partir d’une base de données expérimentale, générée en amont de l’étude sur une unité de type gaz/solide, lit fixe, isobare (3 bara) et isotherme, avec un catalyseur Ta2O5 SiO2. L’influence des conditions opératoires sur l’effluent a été observée pour trois ratios éthanol/acétaldéhyde et sur des gammes de PPH (1,1 à 8,1 g·gcata 1·h-1) et de températures (320 à 370 °C). Le réacteur (piston dispersif sans limitations diffusionnelles) intégrant des lois cinétiques d’ordre, a été modélisé à l’état permanent via un solveur LSODE. Les paramètres cinétiques ont été estimés via un optimiseur Levenberg Marquardt à partir de la base de données expérimentale. Le modèle cinétique obtenu, basé sur un schéma réactionnel inédit, est en capacité de représenter et de prédire les débits des composés principaux et les tendances et ordre de grandeurs des débits des composés minoritaires selon les effets de PPH, de charge et de température, excepté dans certaines conditions opératoires limites isoléesButadiene is a molecule of industrial interest that can be produced by the so-called Ostromislensky process, with ethanol as raw material. This study aims to develop a kinetic model to explain the transformation of an ethanol/acetaldehyde mixture into butadiene, as part of the second step of this process. The kinetic model is based on a reaction scheme and a reactor model. The proposed scheme includes the commonly accepted Gorin Jones pathway and a new pathway involving a butenone intermediate. The key steps were specifically studied via dedicated experiments. The scheme describes also steps leading to by products. It was validated from an experimental database, generated upstream of the study on a gas / solid type unit, fixed bed, isobaric (3 bara) and isothermal, with a Ta2O5 SiO2 catalyst. The influence of the operating conditions on the effluent was observed for three ethanol/acetaldehyde ratios and over ranges of PPH (1.1 to 8.1 g·gcata 1·h-1) and temperatures (320 to 370 °C). The reactor (plug flow without diffusional limitations) integrating kinetic laws of order, was modeled in the permanent state via a solver LSODE. Kinetic parameters were estimated via a Levenberg Marquardt optimizer from the experimental database. The kinetic model obtained, based on a brand new reaction scheme, is able to represent and predict the flow rates of the main compounds and the trends and orders of magnitude of the flow rates of the minority compounds according to the effects of PPH, charge and temperature, except under certain isolated operating conditions
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Azad, Neelam. „Molecular mechanisms of chromium (VI)-induced apoptosis and malignant transformation“. Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5041.
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Thesis (Ph. D.)--West Virginia University, 2007.Title from document title page. Document formatted into pages; contains ix, 103 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.
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Ruiz, Johal. „Nouvelles synthèses par catalyse de composés organosilicés et leur transformation en fragments de polycétides“. Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S138/document.
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La réaction d'aldolisation est une des méthodes les plus importantes et plus utilisées pour former des liaisons C-C. La réaction tandem d'isomérisation-aldolisation catalytique d'alcools allyliques permet d'effectuer cette réaction avec de nombreux avantages synthétiques et nous avons préparé par ce moyen des beta-hydroxyacylsilanes à partir d'alpha-hydroxyallylsilanes. Tout d'abord, nous avons cherché à mettre au point une version catalytique asymétrique de cette réaction tandem et nous avons aussi synthétisé des beta-hydroxyacylsilanes par aldolisation directe. Ensuite, nous avons utilisé des alpha-hydroxyallylsilanes pour préparer des aldolsalpha-silylés au moyen de réactions d'époxydation. Dans une troisième partie, nous avons synthétisé des aldols à partir de beta-hydroxyacylsilanes protégés de manière simple et efficace, ce qui nous a permis d'effectuer des réactions d'aldolisation itératives. Nous avons illustré le potentiel de cette méthode par la synthèse d'un fragment de (±)-pironetine. Enfin, nous avons synthétisé, à partir des mêmes beta-hydroxyacylsilanes protégés, des éthers d'énol silylés qui ont été ensuite utilisés avec succès comme substrats pour des réactions de MukaiyamaThe aldol reactions is one of the most important and commonly used methods to form C-C bonds. The catalytic tandem isomerization-aldol reaction of allylic alcohols allows to perform this reaction with many synthetic advantages. Thus, we have prepared by this method beta-hydroxyacylsilanes from alpha-hydroxyallylsilanes. First, we have attempted to develop a catalytic asymmetric version of this reaction, and also to synthesize beta-hydroxyacylsilanes by direct aldol reaction. Then, we used alpha-hydroxyallylsilanes to prepare alpha-silyl aldols trough epoxidation reactions. Next, we synthesized aldols from protected beta-hydroxyacylsilanes in a simple and efficient fashion which allowed us to perform iterative aldol reactions. We have illustrated the potential of this method by the synthesis of a fragment of (±)-pironetine. Finally, we have synthesized, from the same protected beta-hydroxyacylsilanes, silyl enol ethers that next have been used successfully as substrates for Mukaiyama aldol reactions
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Isaksson, Dan. „Lipase catalysed reactions of terpenoids : formation of hemiacetal esters : resolution of cryptone and its transformation to cadinenes“. Doctoral thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-588.
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COHEN, SYLVAINE-ASTRID. „Elaboration et transformation des intermetalliques a base de tial : frittage reactif et fusion classique“. Paris 11, 1997. http://www.theses.fr/1997PA112116.
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L'objet de cette etude est d'optimiser l'elaboration et la transformation d'alliages biphases a base de tial, principalement selon une voie novatrice basee sur la metallurgie des poudres. Ce travail est complete par l'analyse du comportement mecanique des alliages elabores au laboratoire. Apres l'expose des differentes voies d'elaboration de ces intermetalliques, par frittage reactif de poudres elementaires, frittage-filage de la poudre prealliee ou par fusion classique de copeaux de metal pur, nous avons optimise le filage du produit fritte obtenu et etudie le laminage de l'alliage fondu. De cette etude resulte une description microstructurale detaillee de ces aluminures de titane apres differents traitements thermomecaniques et thermiques. Enfin, le comportement mecanique de ces alliages est assorti d'un traitement fondamental des resultats obtenus, par differentes methodes d'analyse statistique des donnees.
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Odabas, Serhat. „Asymmetric Synthesis Of N-aryl Substituted Chiral 1,4-amino Alcohol Derivatives And Applications In Various Asymmetric Transformation Reactions“. Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608489/index.pdf.
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The asymmetric synthesis of N-aryl substituted chiral 1,4-aminoalcohols and their applications in asymmetric borane reduction and enantioselective diethylzinc addition to benzaldehyde reactions were performed starting from meso anhydride 51 that is the cycloadduct of cyclopentadiene and maleic anhydride. The desymmetrization of meso-anhydride 51 was achieved by using quinine or quinidine with very high enantiomeric excess value (up to 98% ee) and with high chemicalb yield. The quinine-mediated desymmetrization of meso-anhydride 51 with methanol gave (2S,3R)-(-)-cis-monoester 52. The hemiester was subjected to chemoselective amidation with various types of N-aryl substituted amines and then, it was treated with LAH and followed by hydrogenation in the presence of palladium catalyst to get the chiral 1,4-amino alcohols. The catalytic effectiveness of these chiral 1,4-amino alcohol ligands, (2S,3R)-60, (2S,3R)-61, (2S,3R)-62 and (2S,3R)-63 were examined in asymmetric borane reduction and enantioselective diethylzinc addition to benzaldehyde reactions.
Keywords: Amino alcohol, chiral ligand, asymmetric reaction, borane reduction, diethylzinc addition
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Das, Saikat. „FUNDAMENTAL STUDIES OF SURFACTANT TEMPLATED METAL OXIDE MATERIALS SYNTHESIS AND TRANSFORMATION FOR ADSORPTION AND ENERGY APPLICATIONS“. UKnowledge, 2015. http://uknowledge.uky.edu/cme_etds/48.
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This work addresses fundamental aspects of designing templates and curing conditions for the synthesis of mesoporous metal oxide thin films. The first section addresses selection of cationic-carbohydrate surfactant mixtures to synthesize templated silica thin films for selective adsorption of simple carbohydrates based on molecular imprinting. Nuclear magnetic resonance and fluorescence spectroscopy results suggest a novel structure for mixtures of alkyl glucopyranosides or xylopyranosides with cationic (trimethylammonium) surfactants. Despite thermodynamically favorable mixing, the carbohydrate headgroups in the mixed micelle adopt an inverted configuration with their headgroups in the micelle core, and therefore are inaccessible for molecular imprinting. This orientation occurs even when the alkyl tail length of the carbohydrate surfactant is greater than that of the cationic surfactant, but this limitation can be overcome by introducing a triazole linker to the carbohydrate surfactant. The next section addresses the effects of aging conditions on the structural and chemical evolution of surfactant templated silica thin films. The third section describes the synthesis of carbohydrate/cationic surfactant imprinted silica thin films with orthogonally oriented cylindrical pores by modifying the glass surface with a random copolymer. The last part of the dissertation addresses the effect of pore orientation on the transformation mechanism of block copolymer templated titania thin films during high temperature curing. Mesoporous titania thin films can be used for photochemical and solar cell applications, but doing so requires addressing the tradeoff between loss of mesostructural order and growth of crystallinity during thermal treatment. By using advanced x-ray scattering techniques it has been shown that the titania films with vertically oriented pores can better withstand the anisotropic stress that develops during thermal treatment compare to titania films with mixed pore orientation. For instance, films with parallel or mixed pores can only be heated at 400 °C for a brief time (~10 min) without loss of order, while orthogonally oriented films can be heated at 550 °C or greater for extended time periods (on the order of hours) without significant loss of long-range mesopore structure. Detailed kinetic modeling was applied to enable the comparison of activation energy for mesostructure loss in films as a function of pore orientation and thickness.
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Swarts, Andrew John. „Novel transition metal complexes based on N,N and N,P ligands as catalysts for ethylene transformation reactions“. Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86330.
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Breslin, Michael Craig. „Transformation Kinetics of Al2O3/Al Co-Continuous Ceramic/Metal Composite Materials (C4) Produced by a Displacement Reaction Between Liquid Al and Fused SiO2“. The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392902805.
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Yazbek, Lindsey Danese. „Hydrogeochemical Factors Influencing Metal Transport and Transformation in a Stream Impaired by Acid Mine Drainage“. Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent1564478839556002.
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Dandach, Amar. „Transformation de la cellulose en bioproduits : une approche intégrée couplant la catalyse enzymatique et la catalyse hétérogène“. Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1129.
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Ces travaux de thèse portent sur la possibilité de combiner la catalyse hétérogène et la catalyse enzymatique dans une réaction en cascade de transformation de la cellulose en produits d’intérêt. Le prétraitement enzymatique (Celluclast, un cocktail de cellulases) a été choisi comme première étape de transformation de la cellulose en vue de la fragiliser; elle est réalisée dans une solution tampon d’acide acétique et d’acétate de sodium à pH 4,75, à 50°C. Cette étape produit principalement du glucose et modifie structurellement la cellulose résiduelle en diminuant seulement son degré de polymérisation (DP), fournissant de nouvelles extrémités réductrices sans toucher sa cristallinité. L’identification des verrous de la deuxième étape de catalyse hétérogène, réalisée en autoclave à une température supérieure ou égale à 190°C, a consisté à trouver un catalyseur hétérogène qui peut tolérer le milieu réactionnel enzymatique tamponné, qui peut avoir une activité catalytique favorisée sur les celluloses de DP inferieurs et qui peut valoriser le glucose obtenu dans des conditions identiques à la cellulose. Parmi les différentes familles de catalyseurs testés, le catalyseur métallique à base de Pt/charbon, s’est révélé plus efficace que les catalyseurs acides de Lewis et de Brønsted en raison de sa résistance au milieu tamponné et de sa capacité à convertir la cellulose et le glucose dans des conditions identiques malgré l’insensibilité de ce type de catalyseur de la diminution du DP de la cellulose prétraitée. Il a permis de convertir sélectivement la cellulose en propylène et éthylène glycols à 240°C dans une transformation cascade incluant une étape enzymatique suivie d’une étape catalytique hétérogèneThis thesis deals with the possibility of combining heterogeneous catalysis and enzymatic catalysis in a cascade reaction for cellulose transformation into value-added products. The enzymatic pretreatment was chosen as the first cellulose transformation step to weaken the cellulose structure which is carried out in a buffer solution of acetic acid and sodium acetate at a pH 4.75, at 50°C. This step is selective, producing mainly glucose, and it has structurally modified the residual cellulose by only decreasing its degree of polymerization (DP) by providing new reducing ends without affecting its crystallinity. The challenges of the second step, heterogeneous catalysis, which is done in a closed autoclave at a temperature greater than or equal to 190°C, were then to find a heterogeneous catalyst that can tolerate the buffered enzyme reaction medium, that can have a favored activity on lower DP celluloses and that can valorize the obtained glucose and cellulose in identical conditions. Among the different families of catalysts tested, the metallic catalyst based on Pt/carbon was shown to be more efficient than the other Lewis and Brønsted acid catalysts due to its resistance to the buffer medium and its abilities to valorize glucose and cellulose in equivalent conditions despite the independence of this type of catalyst to the reduction of the DP of the pretreated cellulose. It allowed to selectively convert cellulose into propylene and ethylene glycols at 240°C in a cascade reaction including an enzymatic catalytic step and a heterogeneously catalyzed one
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Malki, Abdelhafid. „Transformation électrocatalytique de produits issus de la biomasse : oxydation du fructose sur électrodes d'or et de platine“. Poitiers, 1988. http://www.theses.fr/1988POIT2274.
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L'oxydation electrochimique du fructose en milieu basique et en milieu acide est realisee: une etude cinetique est effectuee, on etudie la modification des proprietes catalytiques superficielles des electrodes par adjonction d'adatomes, on fait plusieurs electrolyses a potentiel programme montrant que l'on obtient par cette reaction un melange d'acides gluconique, tartrique et citrique
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Tavitian, Bernard. „Etude par spectroscopie differentielle infrarouge a transformee de fourier des reactions primaires de la photosynthese“. Paris 6, 1987. http://www.theses.fr/1987PA066642.
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Skoglund, Nils. „Ash chemistry and fuel design focusing on combustion of phosphorus-rich biomass“. Doctoral thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-88505.
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Biomass is increasingly used as a feedstock in global energy production. This may present operational challenges in energy conversion processes which are related to the inorganic content of these biomasses. As a larger variety of biomass is used the need for a basic understanding of ash transformation reactions becomes increasingly important. This is not only to reduce operational problems but also to facilitate the use of ash as a nutrient source for new biomass production. Ash transformation reactions were examined in the present work using the Lewis acid-base concept. The model presented in Paper I was further extended and discussed, including the definition of tertiary ash transformation reactions as reaction steps where negatively charged molecular ions, Lewis bases, other than hydroxides are present in the reactants. The effect of such reactions for bonding of various metal ions, Lewis acids, were discussed. It was found that the formation of various phosphates through secondary and tertiary ash transformation reactions is important for the behaviour of biomass ash in combustion. The suggested model was supported by findings in Papers II-VIII. The experimental findings in Papers II-VIII were discussed in terms of ash transformation reactions. The fuel design choices made to investigate the effect of phosphorus in particular on ash transformation reactions were high-lighted. Addition of phosphoric acid to woody-type and agricultural biomasses showed that phosphate formation has a large influence on the speciation of Si, S, and Cl. Co-combustion of a problematic agricultural residue with other biomasses showed that the relation between phosphorus, alkali and alkaline earth metal content is important. Co-combustion of biosolids with wheat straw was shown to greatly improve the combustion properties of wheat straw. It was suggested that fuel analyses should be presented using molar concentration (mole/kg) in diagrams based on ash transformation reactions and elements forming Lewis acids or bases. This may facilitate the assessment of the combustion behaviour of a fuel. Some comments were made on fuel design and additives, specifically pointing out that phosphorus content should always be carefully considered in relation to alkali and alkaline earth metals in fuels and fuel blends.