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Yue, Junqi. "Destruction of TNT and RDX residues and devices /." View online ; access limited to URI, 2005. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3188852.
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Tsui-Bowen, Alethea. "Solid phase microextraction of amino-dinitrotoluenes in tissue." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc4649/.
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TNT (2,4,6-trinitrotoluene) readily and predominantly transforms to 2ADNT (2-amino-4,6-dinitrotoluene) and 4ADNT (4-amino-2,6-dinitrotoluene) in environmental matrixes and tissues. Solid phase microextraction (SPME) was used to extract ADNTs (amino-dinitrotoluenes) from tissue as a potential method to investigate the recalcitrance of metabolically-generated ADNTs versus absorbed ADNTs. Tubifex tubifex was allowed to metabolize TNT into ADNTs in 24-hr static non-renewal exposure test followed by 24-hr depuration in clean reconstituted hard water. Polyacrylate-coated (PA) SPME fibers were then deployed and agitated in tissue homogenates containing metabolically-generated ADNTs for 48 hr to provide a measure of available ADNTs. Extractability of ADNTs from T. tubifex tissue containing metabolically-generated ADNTs was significantly less than extractability of ADNTs from T. tubifex tissue containing absorbed ADNTs: 50-60% and 81-90% of expected extractability based on fiber-water partition ratio. The lower SPME extractability of metabolically-generated ADNTs may stem from the unavailability of metabolically-generated ADNTs sequestered in tissue or bound to tissue macromolecules during metabolism of TNT to ADNT. Tissue extractions using SPMEs may be able to estimate such bound organic residues in tissue and serve as potential indicators of toxicological bioavailability and biomagnification potential of tissue-associated organic compounds.
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Pannier, Andy Joseph. "Reductive transformation of 2,4,6-Trinitrotoluene by Yarrowia lipolytica AN-L15 under conditions of different initial pH of the culture medium or in the presence of ferrihydrite." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/pannier/PannierA0509.pdf.
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Batch and column studies were conducted to examine the difference in the transformation pathways of 2,4,6-trinitrotoluene (TNT) reduction by a hemiascomycetous yeast (Yarrowia lipolytica AN-L15) under conditions of different initial pH of the culture medium or in the presence or absence of ferrihydrite. Using high performance liquid chromatography (HPLC), it was observed that Y. lipolytica AN-L15 was able to transform TNT at three different initial proton concentrations of the culture medium: pH 7.0, pH 6.5, and pH 4.5. In the presence of TNT, Y. lipolytica AN-L15 showed preferential growth (OD₆₀₀) at the lower initial pH of 4.5. The increased growth (OD₆₀₀) resulted in increased reduction of TNT-metabolites in the culture medium with an initial pH of 4.5, as compared to, the culture medium with an initial pH of 6.5 or the culture medium with an initial pH of 7.0. TNT transformation via aromatic ring reduction was the major transformation pathway observed, with the major metabolite being 3-H̄ -TNT. 4-hydroxylaminodinitrotoluene (4-HADNT) was the major metabolite of the nitro-group reduction pathway. In the presence of ferrihydrite at a pH of 7.0, the transformation of TNT by Y. lipolytica AN-L15 showed a change in the transformation pathway. Nitro-group reduction was the major pathway of TNT transformation in the presence of ferrihydrite with 4-HADNT and 2-aminodinitrotoluene (4-ADNT) being the major metabolites formed. The time it took to reduce TNT was longer and the concentrations of TNT-metabolites were lower in the presence of ferrihydrite than in its absence. This may have been due to competition for available electrons between TNT and TNT-metabolites and Fe(III). It is also possible that some of the intermediate products of TNT transformation were oxidized back to TNT-metabolites by Fe(III) resulting in lower concentrations of TNT-metabolites and increased concentrations of Fe(II). This study demonstrates the complexity of the interactions of various environmental parameters, under controlled laboratory conditions, in the transformation of TNT by Y. lipolytica AN-L15.
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LIU, Fangzhu. "Integration of Chemical Oxidation and Biotreatment for Removal of TNT from Explosives Contaminated Soil." MSSTATE, 2002. http://sun.library.msstate.edu/ETD-db/theses/available/etd-12032002-152100/.
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2,4,6-trinitrotoluene (TNT) is of environmental concern because it?s a possible human carcinogen and it also remains potentially explosive. The Department of the Army (DA) estimates that there are 540,000 cubic meters (700,000 cubic yards) of explosives-contaminated soil at over 2,000 sites that require remediation. Biological treatment of TNT results in the production of the reduced intermediates (such as aminonitrotoluenes). When using chemical oxidation processes to treat TNT, 1,3,5-trinitrobenzene (TNB) is produced. The by-products of both biological and oxidation treatment processes are resistant to further treatment thus they require extensive treatment times. This study evaluated the use of biotic mechanisms that can be used to reduce TNT into aminodinitrotoluenes, which then are oxidized using Fenton?s Reagent oxidation process. Integration experimental results showed that Fenton?s Reagent was capable of degrading TNT, though not as fast as ADNTs. The optimal Fe2+/H2O2 ratio appears to be less than 10:1. The TNT biodegradation rate was higher than the TNT oxidation rate and was biodegraded at a faster rate compared to the ADNTs. It was concluded that the integrated technology showed promise as an effective and innovative technology for treating TNT contaminated soil.
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Dudley, Melissa B. Chambliss C. Kevin. "Accumulation of trifluralin and trinitrotoluene (TNT) in two aquatic invertebrates formation and persistence of unextractable biotransformation products /." Waco, Tex. : Baylor University, 2008. http://hdl.handle.net/2104/5155.
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Walker, Diane Kathryn. "Impact of a model soil on the biotransformation of 2,4,6-trinitrotoluene and its amine metabolites." Thesis, Montana State University, 2004. http://etd.lib.montana.edu/etd/2004/walker/WalkerD04.pdf.
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Hernandez, Rafael. "Integration of zero-valent metals and chemical oxidation for the destruction of 2,4,6-trinitrotoluene within aqueous matrices." Diss., Mississippi State : Mississippi State University, 2002. http://library.msstate.edu/etd/show.asp?etd=etd-11102002-174828.
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Conder, Jason M. "Bioavailability and toxicity of 2,4,6-trinitrotoluene in sediment." Thesis, University of North Texas, 2004. https://digital.library.unt.edu/ark:/67531/metadc5549/.
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TNT (2,4,6-trinitrotoluene) is a persistent contaminant at many military installations and poses a threat to aquatic ecosystems. Data from environmental fate and toxicity studies with TNT revealed that sediment toxicity test procedures required modification to accurately assess sediment TNT toxicity. Key modifications included aging TNT-spiked sediments 8-14 d, basing lethal dose on measured sediment concentrations of the molar sum of TNT and its main nitroaromatic (NA) transformation products (SNA), basing sublethal dose on average sediment SNA concentrations obtained from integration of sediment SNA transformation models, avoiding overlying water exchanges, and minimizing toxicity test durations. Solid phase microextraction fibers (SPMEs) were investigated as a biomimetic chemical measure of toxicity and bioavailability. Both organism and SPME concentrations provided measures of lethal dose independent of exposure scenario (TNT-spiked sediment or TNT-spiked water) for Tubifex tubifex. Among all benthic organisms tested (Chironomus tentans, Ceriodaphnia dubia, T. tubifex) and matrixes, median lethal dose (LC50) estimates based on SPME and organism concentrations ranged from 12.6 to 55.3 mmol SNA/ml polyacrylate and 83.4 to 172.3 nmol SNA/g tissue, ww, respectively. For Tubifex, LC50s (95% CI) based on SNA concentrations in sediment and SPMEs were 223 (209-238) nmol SNA/g, dw and 27.8 (26.0-29.8) mmol SNA/ml, respectively. Reproductive effects occurred at slightly lower exposures. Median effective dose (EC50) estimates (95% CI) for Tubifex cocoon production, based on sediment and SPME concentrations, were 118 (114-122) nmol SNA/g, dw and 21.8 (21.2-22.4) mmol SNA/ml, respectively. Bioconcentration experiments with Tubifex revealed that compound hydrophobicity predicted the toxicokinetics and bioconcentration of these compounds from water, however, there was a large discrepancy between the toxicokinetics of absorbed versus metabolically-generated aminodinitrotoluenes. A large portion of bioconcentrated, radiolabeled TNT transformation products could not be identified. In addition to their ability to provide matrix-independent measures of dose, SPME concentrations were more accurate indicators of bioavailable NAs than were sediment concentrations.
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King, Stephanie. "Capillary Electrophoresis Single-Strand Conformation Polymorphism Analysis for Monitoring Bacteria during the Remediation of TNT-Contaminated Soil." Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1108061640.
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Han, Sungsoo. "In situ bioremediation and natural attenuation of dinitrotoluenes and trinitrotoluene." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24700.
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Thesis (Ph.D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008.Committee Chair: Dr. Joseph B. Hughes; Committee Member: Dr. Jian Luo; Committee Member: Dr. Jim C. Spain; Committee Member: Dr. Patricia Sobecky; Committee Member: Dr. Spyros G. Pavlostathis
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Mohsen, Yehya. "Conception et caractérisation d'une plate-forme microfluidique pour la détection sélective de traces d'un produit de dégradation du TNT dans l'atmosphère." Phd thesis, Université de Franche-Comté, 2013. http://tel.archives-ouvertes.fr/tel-00943211.
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L'objectif de cette étude est de concevoir et caractériser une plate-forme micro-fluidique permettant la concentration et la séparation d'un produit de dégradation du trinitrotoluène :l'ortho-nitrotoluène (ONT) considéré comme un traceur de composés explosifs. Les capteurs àbase de dioxyde d'étain (SnO2) utilisés ici comme détecteurs présentent un réel manque desélectivité et leur sensibilité peut s'avérer insuffisante pour la détection de traces de polluantsdans l'atmosphère. L'approche originale envisagée dans cette étude consiste à travailler en amontdu capteur chimique (SnO2), en particulier, en développant d'une part un micro-préconcentrateurde gaz afin d'améliorer l'aspect sensibilité et d'autre part une micro-colonne chromatographiquepour s'affranchir du manque de sélectivité.Dans un premier temps, une série d'adsorbants ont été étudiés et caractérisés pour laconcentration de l'ONT. Les résultats obtenus ont permis de sélectionner trois types de charbonsactifs (N, KL2 et KL3) et une zéolithe hydrophobe DAY.Ensuite, les micro-systèmes fluidiques ont été réalisés sur un substrat de silicium et élaborés enutilisant la technologie silicium/verre.La dernière partie de ce travail est consacrée à l'évaluation des performances d'analyse de cetteplate-forme en termes de concentration et de séparation de l'ONT. En particulier, après avoirévalué les conditions optimales de concentration et d'élution de l'ortho-nitrotoluène, le couplageentre la plate-forme micro-fluidique et le capteur à base de dioxyde d'étain a permis d'une part demontrer que la limite de détection de l'ortho-nitrotoluène est inférieure à 365 ppb. Dans ce cas,une désorption totale de la molécule cible et un facteur de concentration constant ont été obtenusavec la zéolithe DAY. D'autre part, l'utilisation de ce type de plate-forme a permis d'obtenir unebonne performance de détection et de séparation de l'ONT en présence d'un interférent (toluène)et d'un taux d'hygrométrie élevé.
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Medhi, Gautam. "Intracavity laser absorption spectroscopy using quantum cascade laser and Fabry-Perot interferometer." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4800.
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Intracavity Laser Absorption Spectroscopy (ICLAS) at IR wavelengths offers an opportunity for spectral sensing of low vapor pressure compounds. We report here an ICLAS system design based on a quantum cascade laser (QCL) at THz (69.9 micrometers]) and IR wavelengths (9.38 and 8.1 micrometers]) with an open external cavity. The sensitivity of such a system is potentially very high due to extraordinarily long effective optical paths that can be achieved in an active cavity. Sensitivity estimation by numerical solution of the laser rate equations for the THz QCL ICLAS system is determined. Experimental development of the external cavity QCL is demonstrated for the two IR wavelengths, as supported by appearance of fine mode structure in the laser spectrum. The 8.1 micrometers] wavelength exhibits a dramatic change in the output spectrum caused by the weak intracavity absorption of acetone. Numerical solution of the laser rate equations yields a sensitivity estimation of acetone partial pressure of 165 mTorr corresponding to ~ 200 ppm. The system is also found sensitive to the humidity in the laboratory air with an absorption coefficient of just 3 x 10[super -7] cm[super -1] indicating a sensitivity of 111 ppm. Reported also is the design of a compact integrated data acquisition and control system. Potential applications include military and commercial sensing for threat compounds such as explosives, chemical gases, biological aerosols, drugs, banned or invasive organisms, bio-medical breath analysis, and terrestrial or planetary atmospheric science.ID: 030646266; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 87-95).
Ph.D.
Doctorate
Physics
Sciences
Physics
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Kizaki, Seiichiro. "Chemical Biology Study on DNA Epigenetic Modifications." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225420.
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Islam, Saidul. "Studies towards the chemical origins of life." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/studies-towards-the-chemical-origins-of-life(afeac977-39db-4caa-bcbc-63643f5e9f3e).html.
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The 'RNA World' hypothesis states that RNA was the first living system on the primitive Earth, where it carried out dual genotypic and phenotypic functions. Therefore, RNA must have self-assembled by purely chemical means from small prebiotic feedstock molecules. A plausible demonstration of the synthesis of RNA with the natural [5'→3'] phosphodiester linkage, and its self-replication has not been achieved so far. Some have speculated a 'simpler' informational polymer preceded it, and biology based on this polymer subsequently 'invented' RNA. The structurally simpler L-α-threofuranosyl nucleic acid (TNA) has been proposed as a primordial ancestor to RNA. A study into the potential self-assembly of TNA nucleotides was carried out. It is shown that as a direct result of TNA's structural simplicity, its generational chemistry is more difficult than RNA. The tetrose aminooxazolines are unstable under the conditions of its formation. The tetrose anhydronucleosides efficiently incorporate phosphate to form activated tetrose cytidine-2',3'-cyclic phosphates, but with the wrong stereochemistry. Strong support for the 'RNA world' hypothesis came from a report in 2009 of the prebiotic synthesis of activated pyridimine ribonucleoside-2',3'-cyclic phosphates. Oligomerisation studies were carried out on these activated monomers with various catalysts, and NMR studies were carried out to determine the aspects of their reactivity. It was found that only short oligomers are formed. However, nucleoside-2',3'-cyclic phosphates were found to selectively hydrolyse to a 2:1 mixture of 3' and 2'-monophosphates, and this observation was considered as etiologically relevant. Nucleoside-2' and 3'-monophosphates cyclise back to nucleoside-2',3'-cyclic phosphates upon phosphate activation, and so cannot be considered as direct candidates for oligomerisation. A chemistry that selectively uses the nucleoside-3'-phosphate for the synthesis of RNA, and recycles the unwanted 2'-phosphate would be highly desirable. Thus, a regio- and chemoselective reaction that selectively acetylates monomer and oligomer nucleoside-3'-phosphates at the 2'-hydroxyl in water is presented. Nucleoside-2'-phosphates are shown to acetylate less efficiently, and show a greater propensity to recyclise back to nucleoside-2',3'-cyclic phosphates. Purine nucleotides were also found to acetylate better than pyrimidines. This potentially primordial protecting group chemistry approach towards the prebiotic synthesis of RNA is conceptually novel, and has the potential to give a natural [5'→3'] phosphodiester linkage isomer. It is considered as a major step towards solving the long-standing problem of non-enzymatic self-replication of RNA.
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Al-Salem, S. "Thermo-Chemical Treatment (TCT) of polymers in multi-scale reactors : a kinetics and Life Cycle Assessment (LCA) study." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1394441/.
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The main reasons behind the success of the petrochemicals industry are not only the vast array of products that it provides - considered vital to our daily functions - but also the added value that it brings to the crude oil barrel price, making it a reliable venture for any concerned party. However, the industry is now faced with a fluctuating market and an unstable economy, which makes it imperative to find a more abundant and sustainable feedstock. Of all petrochemical derivatives, polymers (and their related industries) occupy the major share, and this makes the plastics industry a growing sector in terms of processing and conversion. Both virgin and waste plastics represent an attractive source of energy and product recovery. The main objective of this work was to investigate the thermo-chemical treatment (TCT) of polymers at different scales, and the reactors studied ranged from micro laboratory scale to industrial units suitable for covering large market demands. Within this framework, the degressive behaviour of polyolefin polymers (three virgin grades and two recyclate ones) was investigated alongside the products yielded (gases (C1-C4), liquids (non-aromatic C5-C10), aromatics (single ring structures) and waxes (> C11). This was achieved in a micro scale isothermal pyrolysis process, using 15 mg in a laboratory thermogravimetric analyser covering the temperature range of 500-600°C. The analysis led to the development of an nth order novel model on the basis of lumped products yielded by pyrolysis. The degradation mechanism was used to develop the mathematical breakdown of the primary, secondary and tertiary reactions. The model developed predicts the yield of the four different products and the polymer residual fraction at any operating condition proving to be a useful tool for reactor design and simulation, where the production of a specific chemical at a certain operating condition is paramount. In addition, laboratory scale isothermal pyrolysis experiments on end of life tyres (ELTs) were also conducted. This was achieved as a means to demonstrate the application of the concept previously applied to the polyolefins. A thermal cracking (degradation) scheme was proposed based on the global yielded products, which were lumped into four categories, namely gases (C1-C4), liquids (non-aromatic C5-C10), single ring aromatics (C5-C10), and char. The depolymerization kinetics (from primary, secondary and tertiary reactions) evaluation showed a high match with the experimental results obtained in this work. Finally, a life cycle assessment (LCA) was conducted for three integrated scenarios that reflect the current (2012) treatment of waste plastics in the Greater London area. The scenarios studied utilised a fraction of the polymers treated as a feedstock for two industrial scale TCT technologies; namely a low-temperature pyrolysis reactor that works using BP® technology and a hydrocracking unit that utilises the Veba-Combi Cracking (VCC®) concept. The scenarios studied also include transfer stations, a dry materials recovery facility (MRF) and a combined heat and power (CHP) incineration unit. The energy recovered via the different processes studied, as well as the chemicals and petrochemicals recovered, were all considered as credits in the LCA conducted. Chemicals obtained by the TCT units are very valuable and can replace refinery cuts and petrochemicals (e.g. syncrude (crude oil), naphtha, heavy (waxes) fraction (comparable to atmospheric residue), gases (C3 and C4) refinery cuts, etc.). This led to a technoeconomic analysis of the three integrated scenarios in order to assess the overall profitability. The analysis included capital, operating and maintenance costs, gate fees, transportation costs and corporation tax. The eligibility for governmental incentives (i.e. renewable obligation certificates (ROCs), levy exemption certificates (LECs) and packaging recovery notes (PRNs)) was also considered. The results obtained from the work carried out and reported in this thesis point towards ideal strategies for the treatment of polymers within the urban environment. It also provides a detailed understanding of potential products from polymers introduced to TCT units. This also aids the optimum recovery of petrochemicals, chemicals and energy from different TCT processes, and could help the UK Government in meeting its energy policy targets. It can also contribute to the energy security through diversification of supply. Finally, it provides a perspective on the integration between the crude oil upstream industry and different petrochemical complexes and oil refineries, through the use of different TCT units to increase the production of petrochemicals in existing plants.
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Wichmann, Janine. "The role of TNP-Nucleotides, LYS492 and CA²⁺chelators in the skeletal muscle sarcoplasmic reticulum CA²⁺atpase cycle." Master's thesis, University of Cape Town, 1998. http://hdl.handle.net/11427/26917.
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In the first part of this study, the kinetics of decay of TNP-nucleotide superfluorescence was investigated with a view to understanding the role of nucleotides and Lys492 in later steps in the catalytic cycle of the skeletal muscle Ca²⁺ATPase. It has been found previously, and verified here, that tethering TNP-8N₃-AMP to the Ca²⁺ATPase via Lys492 retarded the Ca²⁺ initiated decay of Pᵢ-induced superfluorescence 10-fold compared with untethered nucleotide. The rapidity of the decay upon addition of EDTA suggested that the E₂ ↔ E₁ → E₁Ca₂ steps were being monitored rather than dephosphorylation per se. Tethered diand triphospho species did not accelerate the decay. While monophasic kinetics was observed with untethered TNP-AMP and TNP-8N₃-AMP, complex kinetics were observed with the di- and triphospho TNP-nucleotides. This was shown to be due to the utilization of TNP-ADP and -ATP, and the azido derivatives, as coupled substrates of the Ca²⁺ATPase in the forward direction of catalysis in the presence of Ca²⁺. The hydrolysis rates of TNP-ADP, TNP-ATP, TNP-8N₃ -ADP, and TNP-8N₃ -ATP were 10, 5, 15 and 10 nomoles/min/mg of protein, respectively, at room temperature and pH 5.5. Ca²⁺ transport was supported by all four nucleotides. This is the first time that a diphosphonucleotide has been shown to support Ca²⁺ transport. A new nonhydrolysable triphospho TNPnucleotide, TNP-AMP-PCP was synthesized and shown to interact with the Ca²⁺ATPase in a similar way, in terms of superfluorescence, as the other TNP-nucleotides. It did not show the complex kinetics on inhibition of the Pcinduced superfluorescence by Ca²⁺, but neither did it accelerate the kinetics. It was concluded that TNP-nucleotides do not accelerate the E₂ ↔ E₁ transition under these conditions, possibly because of the presence of glycerol in the medium. In the second part of the study, it was shown that addition of small amounts of chelators EGTA, EDTA, BAPTA, DTPA, HEDTA and NTA to a Ca²⁺ transport assay in which the free Ca²⁺ concentration is monitored by Fluo-3 causes the Ca²⁺ATPase to pump to apparently lower levels as seen in the [Ca²⁺] lim fluorescence. Addition of chelator retards pump function in the sense that it takes longer for 50 nmols Ca²⁺ to be accumulated. Increased thermodynamic efficiency of the pump and contaminating heavy metal ions were considered as possible mechanisms. To some extend Zn²⁺ and Cd²⁺, but not Fe²⁺ and Cu²⁺, appeared to reverse the partial inhibition. While interpretation of the results is difficult, it is suggested that heavy metal ions interact with luminal loops of the Ca²⁺ATPase and enhance Ca²⁺ release under conditions of high luminal Ca²⁺ concentrations.
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Li, Zhengyan, and 李正炎. "The incidence of imposex in Hong Kong and the value of Thais clavigera(Gastropoda: muricidae) as a bioindicator of TBT pollution." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31240586.
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Hu, Xiaohua. "Kinetic Studies of Hydroxyl and Hydrogen Atom Reactions." Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3137/.
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Gas phase kinetics of the reactions involving hydroxyl radical and hydrogen atom were studied using experimental and ab initio theoretical techniques. The rate constant for the H + H2S reaction has been measured from 298 to 598 K by the laser photolysis/resonance fluorescence (LP-RF) technique. The transition state theory (TST) analysis coupled with the measurements support the suggestion that the reaction shows significant curvature in the Arrhenius plot. The LP-RF technique was also used to measure the rate constant of the H + CH3Br reaction over the temperature range 400-813 K. TST and density functional theory (DFT) calculations show that the dominant reaction channel is Br-abstraction. The reaction H + CF2=CF-CF=CF2 was first studied by flash photolysis/resonance fluorescence (FP-RF) method. The experiments of this work revealed distinctly non-Arrhenius behavior, which was interpreted in terms of a change in mechanism. DFT calculations suggest that the adduct is CF2H-CF•-CF=CF2. At lower temperatures a mixture of this molecule and CF2•-CFH-CF=CF2 is likely. The theoretical calculations show that H atom migrates in the fluoroethyl radicals through a bridging intermediate, and the barrier height for this process is lower in the less fluorinated ethyl radical. High level computations were also employed in studies of the rate constants of OH + chloroethylenes reactions. VTST calculations indicate that, except the reaction of OH + C2Cl4, these reactions present a complex behavior. For OH + C2Cl4, conventional TST calculation shows a simple positive temperature-dependence behavior.
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Reddy, V. Venkatashamy. "Etude de couches minces de type LiNiVO4 utilisables en tant qu'électrode négative dans des microbatteries au lithium." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2003. http://tel.archives-ouvertes.fr/tel-00003918.
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Une forte demande en systèmes électrochimiques rechargeables s'est développée durant la dernière décennie afin d'alimenter en énergie des systèmes miniaturisés. Parmi ces nouveaux systèmes figurent notamment les microbatteries. Les avancées technologiques récentes laissent entrevoir un large champ d'applications quant à l'utilisation prochaine de ces dernières. Les couches minces de LiNiVO4 sont des matériaux prometteurs pour une utilisation en tant qu'anode dans des microbatteries au lithium. Toutes les couches minces ont été préparées par pulvérisation cathodique radio-fréquence à effet magnétron à partir d'une cible de LiNiVO4 sous argon pur ou bien un mélange argon/oxygène. Nous avons en particulier étudié l'influence de certains paramètres de dépôt tels que la pression partielle d'oxygène, la puissance, la distance cible-substrat ou la pression totale sur la composition, la microstructure et les propriétés électrochimiques. L'étude de la composition des couches minces déterminée par RBS, NRA et AES a montré que le rapport V/Ni augmente lorsque la pression partielle d'oxygène dans l'enceinte passe de 0 à 10 %. La diffraction des rayons X montre que les couches brutes sont amorphes. Les meilleurs résultats électrochimiques ont été obtenus pour une couche quasi-stoechiométrique, de composition Li1.12NiV1.02O4.11. Cette composition particulière conduit à l'insertion de 7 ions lithium par unité formulaire ce qui correspond à une capacité spécifique de 1000 mAh/g (quand le cyclage est effectué entre 3 V et 0.02 V). Cette dernière est même légèrement améliorée lorsque la couche est recuite à 300°C.
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Dosev, Dosi Konstantinov. "Fabrication, characterisation and modelling of nanocrystalline silicon thin-film transistors obtained by hot-wire chemical vapour deposition." Doctoral thesis, Universitat Politècnica de Catalunya, 2003. http://hdl.handle.net/10803/6324.
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Hot-wire chemical vapour deposition (HWCVD) is a promising technique that permits polycrystalline silicon films with grain size of nanometers to be obtained at high deposition rates and low substrate temperatures. This material is expected to have better electronic properties than the commonly used amorphous hydrogenated silicon (a-Si:H).In this work, thin-film transistors (TFTs) were fabricated using nanocrystalline hydrogenated silicon film (nc-Si:H), deposited by HWCVD over thermally oxidized silicon wafer. The employed substrate temperature during the deposition process permits inexpensive materials as glasses or plastics to be used for various applications in large-area electronics. The deposition rate was about one order of magnitude higher than in other conventionally employed techniques. The deposited nc-Si:H films show good uniformity and reproducibility. The films consist of vertically grown columnar grains surrounded by amorphous phase. The columnar grains are thinner at the bottom (near the oxide interface) and thicker at the top of the film. Chromium layer was evaporated over the nc-Si:H in order to form drain and source contacts. Using photolithography techniques, two types of samples were fabricated. The first type (simplified) was with the chromium contacts directly deposited over the intrinsic nc-Si:H layer. No dry etching was involved in the fabrication process of this sample. The transistors on the wafer were not electrically separated from each other. Doped n+ layer was incorporated at the drain and source contacts in the second type of samples (complete samples). Dry etching was employed to eliminate the nc-Si:H between the TFTs and to isolate them electrically from each other.
The electrical characteristics of both types of nc-Si:H TFTs were similar to a-Si:H based TFTs. Nevertheless, some significant differences were observed in the characteristics of the two types of samples. The increasing of the off-current in the simplified structure was eliminated by the n+ layer in the second type of samples. This led to the improving of the on/off ratio. The n+ layer also eliminated current crowding of the output characteristics. On the other hand, the subthreshold slope, the threshold voltage and the density of states were slightly deteriorated in the samples with incorporated n+ layer. Surface states created by the dry etching could be a possible reason. Other cause could be a bad quality of the nc-Si:H/SiO2 interface. The TFTs with incorporated n+ contact layer and electrically separated on the wafer were used in the further studies of stability and device modelling.
The nc-Si:H TFTs were submitted under prolonged positive and negative gate bias stress in order to study their stability. We studied the influence of the stressing time and voltage on the transfer characteristics, threshold voltage, activation energy and density of states. The threshold voltage increased under positive gate bias stress and decreased under negative gate bias stress. After both positive and negative stresses, the threshold voltage recovered its initial values without annealing. This behaviour indicated that temporary charge trapping in the channel/gate insulator interface is the responsible process for the device performance under stress. Measurements of space-charge limited current confirmed that bulk states were not affected by the positive nor by negative stress.
Analysis of the activation energy and the density of states gave more detailed information about the physical processes taking place during the stress. Typical drawback of the nc-Si:H films grown by HWCVD with tungsten (W) filament is the bad quality of the bottom, initially grown, interfacial layer. It is normally amorphous and porous. We assume that this property of the nc-Si:H film is determining for charge trapping and the consecutive temporary changes of the TFT's characteristics. On the other hand, the absence of defect-state creation during the gate bias stress demonstrates that the nc-Si:H films did not suffer degradation under the applied stress conditions.
The electrical characteristics and the operational regimes of the nc-Si:H TFTs were studied in details in order to obtain the best possible fit using the Spice models for a-Si:H and poly-Si TFTs existing until now. The analysis of the transconductance gm showed behaviour typical for a-Si:H TFTs at low gate voltages. In contrast, at high gate voltages unexpected increasing of gm was observed, as in poly-Si TFTs. Therefore, it was impossible to fit the transfer and output characteristics with the a-Si:H TFT model neither with poly-Si TFT model.
We performed numerical simulations using the Silvaco's Atlas simulator of semiconductor devices in order to understand the physical parameters, responsible for the device behaviour. The simulations showed that the reason for this behaviour is the density of acceptor-like states, which situates the properties of nc-Si:H TFTs between the amorphous and the polycrystalline transistors. Taking into account this result, we performed analysis of the concentrations of the free and the trapped carriers in nc-Si:H layer. It was found that nc-Si:H operates in transitional regime between above-threshold and crystalline-like regimes. This transitional regime was predicted earlier, but not experimentally observed until now. Finally, we introduced new equations and three new parameters into the existing a-Si TFTs model in order to account for the transitional regime. The new proposed model permits the shapes of the transconductance, the transfer and the output characteristics to be modelled accurately.
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Datta, Saurav. "FUNCTIONALIZED POLYMERIC MEMBRANES FOR BIOSEPARATION AND BIOCATALYSIS." UKnowledge, 2007. http://uknowledge.uky.edu/cme_etds/26.
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Functionalized polymeric membrane based techniques are becoming increasingly popular in biotechnology, food and pharmaceutical industries due to their versatility and hydrodynamic benefits over traditional materials and methods. This research work has been directed towards the development of functionalized polymeric membranes, extensive experimental and theoretical analyses of some of the fundamental aspects of accessibility, membrane fouling and enzyme catalysis, and applications in affinity based bioseparation and biocatalysis. In this research work, the impact of different types of functionalization techniques, such as functionalization of different membrane materials, covalent and electrostatic immobilization, on interaction of various biomolecules and active sites in membrane has been studied in detail.
Avidin was used as model biomolecule, and covalently immobilized within acyl anhydride derivatized nylon based membrane. Quantification of the accessibility of covalently immobilized avidin sites was carried out by model biotinylated probe molecules, such as biotin 4-amidobenzoic acid and biotinylated-BSA. This study has been further extended to separate and purify a target protein, HIV-Tat, from a complex mixture of proteins (97-99 % unwanted protein) using avidin-biotin affinity interaction. It has been demonstrated that covalent immobilization of avidin in membranes reduces the accessibility of active sites for probe molecules. Accessibility decreases further for the biotinylated target protein present in the mixture of other unwanted proteins. Affinity based membrane separation of proteins is also associated with decrease in permeate flux due to fouling in membrane structure. Fouling in the membrane has been discussed by analyzing the characteristics of adsorbed protein layer in membrane.
In order to improve the accessibility and fouling behavior of affinity separation of Tat protein, a pre-filtration step has been introduced prior to affinity separation. Significant enhancement in accessibility and reduction in fouling has been observed for pre-filtered cases as it removes unwanted proteins prior to affinity interaction. Contribution of the pre-filtration step in reduction of fouling has been elucidated by simple model equations. Improvement in accessibility and fouling behavior reflects in higher separation efficiency (protein recovery) and lower processing time for the pre-filtered cases. Quality of membrane purified Tat protein was examined by different analytical techniques, such as SDS-PAGE, Western Blot and biotin analysis, and then compared with that purified by traditional packed-bead column chromatography. It has been demonstrated that membrane based technique was able to isolate superior quality of pure monomeric Tat protein compare to column chromatographic technique.
The other study carried out as a part of this dissertation, has involved development of high capacity, highly active, stable and reusable functionalized membrane domains for electrostatic immobilization of enzymes. Glucose oxidase (GOX) was used as a model enzyme to study the oxidation of glucose to gluconic acid and hydrogen peroxide under convective flow condition. Two different approaches of functionalization of membranes have been presented. In the first approach, alternative electrostatic attachment of cationic and anionic polyelectrolytes was carried out using Layer-By-Layer (LBL) assembly technique within a functionalized nylon based membrane. In the second one, a hydrophobic PVDF membrane was functionalized by in-situ polymerization of acrylic acid. Kinetics of glucose oxidation, effect of pH and flow rate on the activity of GOX was discussed. A comparative study was presented between the activity of free GOX, electrostatically immobilized GOX and covalently immobilized GOX, along with the advantage of convective mode of operation over soaking mode. A novel study has also been conducted on detachment and reattachment of GOX in the same membrane matrix.
Further study has been directed towards implementation of the above mentioned immobilized enzymatic system for oxidative dechlorination of chloro-organics. A first time attempt was made to use a 2-stack functionalized membranes system for simultaneous enzymatic production of hydrogen peroxide in first membrane, and oxidative dechlorination of 2, 4, 6-trichlorophenol (TCP) in the Fe+2 immobilized (by ion exchange) second membrane by Fenton reaction. The technique was efficient in destruction of TCP as evident from the overall dechlorination of 70-80 %. This technique provides additional benefit of reusing the same membrane matrices by reattaching fresh GOX and Fe+2.
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Genevès, Thomas. "Elaboration et caractérisation de couches ultra-minces de silicate de baryum en tant qu'oxyde de grille alternatif." Phd thesis, Université de Bourgogne, 2008. http://tel.archives-ouvertes.fr/tel-00359449.
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La miniaturisation des dispositifs élémentaires de la technologie CMOS impose le remplacement de l'oxyde de silicium pour l'élaboration de l'oxyde de grille. Par l'identification des conditions de formation du silicate de baryum au contact direct du substrat de silicium, cette étude a révélé un candidat potentiel. En premier lieu, la réaction entre Ba et SiO2 aboutissant à la formation d'un silicate de baryum a été mise en évidence in-situ par XPS et SR-PES. Dans un second temps, des films de silicate de baryum ont été élaborés par co-déposition de baryum et d'oxygène à une température de 580 °C. Des traitements thermiques sous vide ont montré que le silicate de baryum est stable jusqu'à 900 °C. Des analyses ex-situ par SIMS et MET ont révélé une interface abrupte avec le substrat. Enfin, un dispositif dédié à la réalisation de croissances par MOCVD a été développé. Il a permis de montrer la possibilité de former un silicate de baryum. La réaction est favorisée lorsque le dépôt se déroule à température élevée, sous une pression partielle d'oxygène.
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Dietrich, Elodie. "Synthèse et études physico-chimiques de verres bioactifs denses et poreux.Applications en tant que biomatériaux en sites osseux." Phd thesis, Université Rennes 1, 2008. http://tel.archives-ouvertes.fr/tel-00344630.
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Ce travail concerne l'élaboration, l'étude physico-chimique et l'évaluation biologique de verres bioactifs purs et dopés, sous forme massive ou poreuse. Trois éléments dopants (Mg, Zn et Sr) ont été introduits, séparément puis simultanément, dans la matrice vitreuse. Les différents verres du système SiO2-CaO-Na2O-P2O5, synthétisés par fusion à haute température, présentent une structure amorphe et homogène. Leur réactivité chimique a été évaluée lors de tests in vitro en l'absence puis en présence de cellules. La bioactivité des verres est avérée par la formation d'une couche d'hydroxyapatite à leur surface. L'introduction d'éléments dopants influe fortement sur la dissolution de la matrice vitreuse, ainsi que sur la cinétique de formation et la cristallisation de la couche d'hydroxyapatite. Ces résultats ont été obtenus par un ensemble de techniques de caractérisations, telles que la DRX, l'IR, le MEB-EDX ou l'ICP-OES. La non-cytotoxicité des verres et une bonne prolifération cellulaire à leur surface a également été mise en évidence. En outre, une étude structurale originale sur la bioactivité des verres par RMN du Solide a mis en évidence la formation de deux nouvelles espèces de tétraèdres SiO4 dans le réseau vitreux et l'apparition d'une nouvelle composante PO43-(HA), caractéristique de l'hydroxyapatite, lors des tests in vitro. Par ailleurs, deux phosphosilicates présentant une porosité macro et micrométrique ont été synthétisés par réaction entre un nitrure, tel que TiN, et les oxydes du verre. Cette porosité a été créée après une mise au point des différents paramètres thermiques nécessaires à ce phénomène.
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Oukacha, Khadija. "Perturbation chimique du transport de Tumor Necrosis Factor." Electronic Thesis or Diss., Université Paris sciences et lettres, 2023. http://www.theses.fr/2023UPSLS067.
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Alors qu'il est essentiel pour lutter contre les agents pathogènes, TNF (Tumor Necrosis factor) secrété́ en excès devient nocif pour l'organisme comme dans le cas de maladies inflammatoires chroniques (polyarthrite rhumatoïde ou maladie de Crohn). Les thérapies actuelles sont basées sur des injections récurrentes d'anti-TNF contre lesquelles 30% des patients développent une résistance. Il existe donc un fort besoin de composés chimiques réduisant la sécrétion de TNF. Nous avons exploité la diversité́ des voies de sécrétion dépendantes de l’appareil de Golgi pour identifier des molécules inhibant spécifiquement la sécrétion de TNF. L’outil RUSH (Retention Using Selective Hooks) a permis la synchronisation et l’analyse du transport de TNF dans les cellules HeLa. En combinant le test RUSH à un criblage phénotypique différentiel de banques chimiques, 85 molécules inhibant le transport de TNF ont été sélectionnées. Les effets de certaines molécules ont été validés. Seules les molécules inhibantes au moins 40% de la sécrétion de TNF ont été retenues. La spécificité de ces molécules sur le transport d’autres protéines, à savoir EGFP-GPI et IL-6 a été évaluée. Les 14 molécules inhibantes plutôt spécifiquement la sécrétion de TNF ont été retenues pour poursuivre leur caractérisation en modèle physiologique.Les effets des molécules sur la sécrétion endogène de TNF et d’autres cytokines ont été mesurés dans des monocytes et des macrophages primaires humains issus du sang de donneurs après incubation avec du lipopolysaccharide (LPS) bactérien. Ces expériences en modèles physiologiques ont mis en évidence trois molécules capables d'inhiber significativement la sécrétion endogène de TNF sans affecter la sécrétion d'IL-8. Des expériences de dose-réponse et l’évaluation des effets des molécules sur l’expression de TNF ont été réalisées pour aider dans la compréhension du mode d’action de ces molécules.En conclusion, le criblage chimique, les expériences en modèle hétérologue puis en modèles physiologiques ont permis d'identifier 3 molécules inhibant la sécrétion de TNF. Ces résultats confirment que la diversité́ des voies sécrétoires est suffisamment grande pour cibler le transport d'une protéine impliquée dans une maladie et pourraient ouvrir la voie à des traitements alternatifs ou complémentaires contre les maladies inflammatoiresWhile it is essential to fight against pathogens, TNF (Tumor Necrosis factor) secreted in excess becomes harmful to the body as in the case of chronic inflammatory diseases (rheumatoid arthritis or Crohn's disease). Current therapies are based on recurrent injections of anti-TNF against which 30% of patients develop resistance. There is therefore a strong need for chemical compounds which reduce the secretion of TNF. We have exploited the diversity of secretory pathways dependent on the Golgi apparatus to identify molecules that specifically inhibit TNF secretion. The RUSH (Retention Using Selective Hooks) tool allowed the synchronization and analysis of TNF transport in HeLa cells. By combining the RUSH assay with a differential hight content screening of chemical libraries, 85 molecules inhibiting TNF transport were selected. The effects of certain molecules have been validated. Only molecules inhibiting at least 40% of TNF secretion were retained. The specificity of these molecules on the transport of other proteins, namely EGFP-GPI and IL-6 was evaluated. The 14 molecules rather specifically inhibiting the secretion of TNF were selected to continue their characterization in a physiological model.The effects of the molecules on the endogenous secretion of TNF and other cytokines were measured in human primary monocytes and macrophages obtained from blood donors after incubation with bacterial lipopolysaccharide (LPS). These experiments in physiological models have demonstrated three molecules capable of significantly inhibiting the endogenous secretion of TNF without affecting the secretion of IL-8. Dose-response experiments and the evaluation of the effects of molecules on the expression of TNF have been carried out to help in understanding the mode of action of these molecules.In conclusion, the chemical screening, the experiments in heterologous model then in physiological models made it possible to identify 3 molecules inhibiting the secretion of TNF. These results confirm that the diversity of secretory pathways is large enough to target the transport of a protein involved in a disease and could open the way to alternative or complementary treatments against inflammatory diseases
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Tran, Nicolas. "Etude des phases Li1+x(Ni0.425Mn0.425Co0.15)1-xO2 en tant que matériaux d'électrode positive pour batteries lithium-ion." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2005. http://tel.archives-ouvertes.fr/tel-00142944.
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Des matériaux lamellaires d'électrode positive pour batteries lithium-ion, de formule Li1+x(Ni0.425Mn0.425Co0.15)1-xO2 (0 < x < 0.12), ont été synthétisés par coprécipitation. Leurs propriétés structurales et physico-chimiques ont été caractérisées par diffraction (rayons X, neutrons et électrons), spectroscopie XPS, mesures magnétiques ... La surlithiation (Li / (Ni+Mn+Co) > 1) entraîne la présence de lithium en excès dans le site des métaux de transition. Une surstructure de type v3.ahex. x v3.a hex. analogue à celle observée pour Li2MnO3 a été mise en évidence par diffraction électronique. Les propriétés électrochimiques et les modifications structurales observées au cours du cyclage ont été caractérisées pour ces matériaux. La surlithiation entraîne la présence d'un " plateau " de potentiel à ~ 4.5V/Li pour le système Li // Li(Ni0.425Mn0.425Co0.15)0.88O2 ; celui-ci a été associé à des changements structuraux irréversibles mettant en jeu une réorganisation cationique dans les feuillets et une perte d'oxygène.
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Lin, Li. "Conception et synthèse de nouveaux aryl C-glycosides en tant qu'inhibiteurs de PTP-1B ou GP et leurs activités biologiques." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2007. http://tel.archives-ouvertes.fr/tel-00258958.
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La protéine tyrosine phosphatase 1B (PTP 1B) et la glycogène phosphorylase (GP) sont des nouveaux cibles thérapeutiques pour le traitement du diabète (type II) et l'obésité. Dans l'objective de trouver des inhibiteurs actives et sélectives de ces enzymes, des aryl C glycosides tels que les C glycosyl 1,4 naphthaquinones, les 6 O benzoyl C glycosyl benzoquinone /naphthaquinones, les dérivés quinone d'acides glycuroniques et d'amides carboxylés ainsi que les inhibiteurs bidentates C glycosyl quinones ont été conçus et synthétisés. En tout, 178 composés ont été préparés. Le mécanisme et les facteurs d'influence de la réaction de C aryl glycosylation ont également été étudiés. Les essais préliminaires montrent que certaines molécules présentent des activités biologiques très intéressantes. Des études biologiques plus approfondies seront réalisées par la suite.
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Pailleux, Mélanie. "Etude in vitro de la toxicité de nanoparticules de boehmite." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2012. http://tel.archives-ouvertes.fr/tel-00782444.
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Cette étude a pour objectif d'apporter des éléments de réponse à la compréhension de la nature et de l'origine des effets biologiques des nanoparticules (NP) de boehmite en réalisant des tests de contacts in vitro sur des macrophages de culture (RAW 264.7), les macrophages étant la cible cellulaire privilégiée au niveau du tractus respiratoire. Différents domaines de la réponse cellulaire en relation avec les propriétés physico-chimiques des particules ont été étudiés. Dans une première partie l'activité biologique a été mesurée sur des NP de boehmite puis après broyage ou dispersion permettant d'observer en particulier l'influence de la taille des particules dans la réponse cellulaire.Les résultats soulignent que les particules industrielles de boehmite sont principalement caractérisées par une activité modérée au niveau de la réponse inflammatoire, mais sans effet cytotoxique ou sans stress oxydant significatif. Des différences en fonction de la taille des particules ont été observées sur les paramètres inflammatoire et cytotoxique.Toutefois, les mesures des biomolécules libérées dans les surnageants de culture cellulaire peuvent être biaisées par l'adsorption de ces biomolécules sur les NP en présence. Ainsi, ce mécanisme d'adsorption doit être pleinement compris pour éviter une interprétation erronée des données obtenues. Dans un second temps l'objectif a donc été d'élaborer une méthodologie afin d'évaluer les interactions organo-minérales en terme d'affinité et de quantité de biomolécules adsorbées sur les nanoparticules à l'équilibre thermodynamique et de déterminer une loi de correction. Dans ce contexte nous nous sommes intéressés en particulier au TNF-α.
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Vahid, Amir. "An Efficient Molecular Theory And Simulation Methodology For Explicit Treatment Of Polarity." University of Akron / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1335290629.
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Grant, David James. "Bottom-Gate TFTs With Channel Layer Deposited by Pulsed PECVD." Thesis, University of Waterloo, 2004. http://hdl.handle.net/10012/805.
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Nanocrystalline silicon (nc-Si:H) is a promising material for Thin-Film Transistors (TFTs) offering potentially higher mobilities and improved stability over hydrogenated amorphous silicon (a-Si:H). The slow growth rate of nc-Si:H can be overcome by using pulsed Plasma-Enhanced Chemical Vapour Deposition (PECVD). Pulsed PECVD also reduces powder particle formation in the plasma and provides added degrees of freedom for process optimization. Unlike high frequency PECVD, pulsed PECVD can be scaled to deposit films over large areas with no reduction in performance.
For this thesis, silicon thin films were deposited by the pulsed PECVD technique at a temperature of 150 °C and TFTs were made using this material. Radio Frequency (RF) power and silane (SiH4) flow rate were varied in order to study the effect of different levels of crystallinity on the film.
Raman spectroscopy, Atomic Force Microscope (AFM), X-Ray Diffraction (XRD), electrical conductivity, Hall mobility, optical band gap, and stability under light-soaking were measured using films of two different thicknesses, 50 nm and 300 nm. From the Raman data we see that the 50 nm films deposited with high hydrogen dilution are mostly amorphous, indicating the presence of a thick incubation layer. The 300nm samples deposited with hydrogen dilution, on the other hand, showed very high crystallinity and conductivity, except for 300-2 which was surprisingly, mostly amorphous. AFM and XRD measurements were also performed to confirm the Raman data and get an estimate for the crystallite grain size in the 300 nm samples. The conductivity was measured for all films, and the Hall mobility and carrier concentration was measured for one of the 300 nm films. The thin samples which are mostly amorphous show low conductivity whereas the thick high crystallinity films show high conductivity, and n-type behaviour possibly due to oxygen doping. The optical gap was also measured using Ultra Violet (UV) light and results indicate the possible presence of small crystallites in the 50 nm films. The conductivity's stability under light-soaking was measured to observe the material's susceptibility to degradation, and the 300 nm with high crystallinity were much more stable than the a-Si:H films. All the results of these measurements varied depending on the film and these results are discussed.
Bottom-gate TFTs were fabricated using a pulsed PECVD channel layer and an amorphous silicon nitride (a-SiN:H) gate dielectric. The extracted parameters of one of the best TFTs are μsat ≤ 0. 38 cm2 V-1 s-1, Vt,sat ≥ 7. 3 V, Ion/off > 106, and S < 1 V/decade. These parameters were extracted semi-automatically from the basic Field-Effect Transistor (FET) model using a computer program. Extraction using a more complicated model yielded similar results for mobility and threshold voltage but also gave a large power parameter α of 2. 31 and conduction band tail slope of 30 meV. The TFT performance and material properties are presented and discussed.
On this first attempt at fabricating TFTs using a nc-Si:H channel layer deposited by pulsed PECVD, results were obtained which are consistent with results for low temperature a-Si:H TFTs and previous pulsed PECVD TFTs. The channel layer was mostly amorphous and non-crystalline, possibly due to the amorphous substrate or insufficient hydrogen dilution in the plasma. The 300 nm films showed, however, that high crystallinity material deposited directly on glass can easily be obtained, and this material showed less degradation under light-soaking than the purely amorphous counterpart. Pulsed PECVD is a promising technique for the growth of nc-Si:H and with further materials development and process optimization for TFTs, it may prove to be useful for the growth of high-quality nc-Si:H TFT channel layers.
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Gong, Yong-Hua. "Etudes de synthèse électrochimiques et de fluorescence de nouveaux dérivés de la 1,2,4,5-tétrazines en tant que sondes moléculaires pour des anions et des composés riches en électrons et étude de synthèses électrochimiques de sels de ferrocène à base de pyridinium." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2007. http://tel.archives-ouvertes.fr/tel-00160587.
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Cette thèse se compose de deux parties. La première traite de la synthèse et des études électrochimiques et de fluorescence de nouveaux dérivés de la 1,2,4,5 tétrazine en tant que sondes moléculaires pour des anions et des composés riches en électrons. La seconde traite de la synthèse et des études électrochimiques préliminaires de sels de ferrocène à base de pyridinium. Dans la partie I, une vue d'ensemble de la chimie des 1,2,4,5 tétrazine (s tétrazines) est présentée. Les stétrazines ont déjà trouvé des applications dans beaucoup de domaines, mais leur capacité à se lier avec des anions ou des composés riches en électrons par interactions anion n ou empilement n'a été démontrée que très récemment. Dans ce contexte, une série de nouvelles sondes moléculaires contenant des noyaux tétrazine servant d'unités liantes et de détection a été conçue, comprenant des pinces tétrazines, des trépieds tétrazines, des cyclophane tétrazines, et des calices tétrazines. Parmi eux, un trépied tétrazine (86), deux cyclophane tétrazines (90, 93) et deux calices tétrazines (94, 95) ont été synthétisés avec succès en se basant sur des réactions de type SNAr avec la 3,6 dichloros tétrazine (23). Les études photophysiques prouvent que la fluorescence de 86, 90, 94 et 95 peut être efficacement éteinte par les composés riches en électrons tels que la triphénylamine (TPA), la tris (4 bromophényl) amine, le pyrrole, le tétrathiafulvalène (TTF) et le 1,3,5 triméthoxybenzène. Les études électrochimiques indiquent également la présence d'interactions entre les sondes de tétrazine et ces composés électrodonneurs. Les mécanismes d'extinction de fluorescence sont étudiés dans certains cas, et des calculs d'orbitales moléculaires sont présentés pour expliquer le rapport entre les structures et les propriétés moléculaires de fluorescence. Dans la partie II, la synthèse d'un sel de pyridinium à deux branches contenant des ferrocènes (45j) et de deux analogues à trois branches (46h, 46j) obtenus par condensations du 1,2,6 triméthylpyridinium ou 1,2,4,6tétraméthylpyridinium avec des aldéhydes aromatiques est présentée. Une nouvelle voie de synthèse est également développée pour les deux intermédiaires importantes, le trans 5 (2 ferrocényl vinyl) 2 carbaldéhydethiophène (47), et l'aldéhyde du ferrocényléthényl bithiophényle (48). Les études électrochimiques préliminaires prouvent que les sousunités bithiophène influencent considérablement le comportement redox des molécules.
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Pereira, Fernando. "Production d'acide phosphorique par attaque chlorhydrique de minerais phosphatés avec réduction des nuisances environnementales et récupération des terres rares en tant que sous-produits." Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2003. http://tel.archives-ouvertes.fr/tel-00802984.
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La voie sulfurique pour la production d'acide phosphorique (destiné à l'industrie des engrais) présente de nombreux inconvénients : impossibilité de récupération de sous-produits de haute valeur commerciale tels les terres rares, existence de fortes restrictions conditionnées par les lois de protection de l'environnement, 250 millions de tonnes de phosphogypse impur et radioactif annuellement produites, problèmes environnementaux liés au stockage du phosphogypse (pollution des nappes phréatiques, des cours d'eau, ). Cette technologie de traitement de la roche phosphatée est de loin la plus répandue (essentiellement en raison d'impératifs économiques). Elle est la seule, à ce jour, suivie au Brésil. Pour ce pays, qui ne dispose pas de dépôts économiques de soufre, le choix d'un autre procédé s'impose d'une part pour réduire ses importations en soufre et, d'autre part pour réduire les nuisances écologiques générées lors de la formation de phosphogypse.Pour cela, il faut étudier des voies et des méthodologies alternatives à la traditionnelle voie sulfurique pour opter pour celle qui offre le plus d'avantages écologiques, économiques et techniques. Le Brésil, possédant une capacité oisive importante en acide chlorhydrique, nous nous sommes logiquement intéressés à la voie chlorhydrique.Nos travaux ont essentiellement porté sur le concentré phosphaté d'Angico dos Dias (concession de la société brésilienne GALVANI), bien que nous ayons également mené des essais en parallèle (à titre comparatif) sur un concentré phosphaté marocain d'origine sédimentaire (minerai utilisé par Grande Paroisse). Nous avons tout d'abord procédé à la caractérisation du concentré et du minerai phosphaté d'Angico dos Dias au niveau minéralogique, granulométrique et chimique avant d'entamer une étude de laboratoire
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Sergeeva, Yulia. "Complexes ADN/polycation en solution et aux interfaces en tant que vecteurs de transfection non viraux de pointe." Phd thesis, Université de Strasbourg, 2013. http://tel.archives-ouvertes.fr/tel-01064224.
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Ma thèse a porté sur des complexes de polyélectrolytes en solution et en films LbL pour la transfection de cellules et le contrôle des interactions cellule-surface. Il est possible de doser un agent de transfection et de l'ADN plasmidique dans des films LbL en ajustant le nombre de couches. Les efficacités de transfection avec différentes lignées cellulaires ont été au moins aussi bonnes que celles rapportées dans la littérature, mais sont restées globalement faibles. Différents nanobags ont également été systématiquement testés menant à un protocole de transfection très efficace avec une faible cytotoxicité pour des fibroblastes humains qui sont difficiles à transfecter. Nous avons pu identifier les architectures LbL qui permettent de contrôler l'adhésion cellulaire même en présence de sérum. Cela nous a permis d'introduire une nouvelle technique pour le suivi in situ de la transfection par QCM-D en suivant la mobilité du cytosquelette qui sera poursuivie dans un futur projet.
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Barnych, Bogdan. "Synthetic studies toward plakortolides : asymmetric synthesis of ent-plakortolide I and seco-plakortolide E." Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00923550.
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In this thesis manuscript are described our synthetic efforts and the first total synthesis of two natural products isolated from the sponges of the genus Plakortis. In total, two different synthetic approaches were studied to finally accomplish the synthesis of plakortolide I. The first approach is an extension of the method developed by our group which consists in the creation of the 1,2-dioxane cycle by intramolecular opening of vinyl epoxide with β-hydroperoxy group. Firstly, we was interested in the preparation of alkoxymethylhexa-2,5-dien-1-ol. We have also tried to create the 1,2-dioxane cycle by double opening of bis-1,5-epoxide with hydrogen peroxide. Further more we have synthesised trisubstituted β-hydroperoxy vinyl epoxide, precursor of 1,2-dioxan ring, from R-epichlorohydrin. During this synthesis a procedure of chemoselective methylenation of ketone in the presence of epoxide by Nysted reagent and Ti(OiPr)2Cl2 was developed. Finally, (-)-ent-plakortolide I and seco-plakortolide E were synthesised by intramolecular Michael addition of hydroperoxide to double bond of the butenolide moiety
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Warke, Rajas V. "Molecular Dissection of the Cellular Reponse to Dengue Virus Infection." eScholarship@UMMS, 2008. https://escholarship.umassmed.edu/gsbs_diss/366.
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The immune response to viral infection involves a complexity of both innate and adaptive pathways at the cellular and the molecular level. There are many approaches to begin to define the pathways at work to control viral pathogenesis. The approach favored in this thesis was to conduct a broad screen of the innate immune response at the gene expression level of infected cells.
The innate immune response is critical to the control of viral infections. Type I interferons (IFN), IFNα and IFNβ, are antiviral proteins that are an integral part of the innate immune response. Furthermore, by virtue of their effects on maturation and activation of antigen-presenting cells, IFNs are a pivotal link between the innate and adaptive immune systems. Most cell types produce type-I IFN when exposed to viruses. However, viruses have evolved multiple strategies to suppress IFN production or signaling. It is imperative to understand the virus-host interaction at the molecular level in order to identify as yet unknown mechanisms of the host antiviral response; these additional pathways may be useful in counteracting the viral suppression of IFN. Type-I IFNs regulate expression of at least five hundred genes, suggesting a complex network of signaling pathways. Depending on the cell type different proteins regulate the induction of IFN or the expression of IFN-inducible genes. Identification of proteins that induce selected IFN-inducible genes may provide synergistic activity with or may have an advantage over type-I IFN for anti-viral therapy in the future.
Many diseases are untreatable if identified late in their progression. In resource-limited countries, many diseases are diagnosed clinically, which can lead to incorrect or delayed diagnosis and treatment. The identification of biomarkers of disease has the potential to guide the correct therapy in a timely fashion. The objective of this thesis was to identify novel anti-viral therapies and disease biomarkers for dengue virus (DENV) infection.
DENV is a mosquito-borne positive-sense single-stranded RNA virus, which causes an estimated 50 million infections annually. Most DENV infections result in a febrile illness called Dengue fever (DF). Less frequently, infections cause Dengue hemorrhagic fever (DHF), a potentially fatal vascular leakage syndrome associated with the production of pro-inflammatory cytokines. At present patients infected with DENV can only be treated by intravenous fluid support to prevent hypovolemia and hypotensive shock. This treatment is less effective in severe cases if the diagnosis is delayed. Identification of therapeutics with both antiviral and immune-modulatory activity may lower patient mortality and reduce the burden of DENV on society.
DENV infection is cleared in most individuals after a short period of viremia {Libraty, 2002 #2225}. Based on in vitro and mouse models, type-I and type-II IFN signaling pathways are thought to be critical in the regulation of DENV infection. Higher serum levels of type I and type II IFNs during acute DENV infection in patients lend support to the above hypothesis {Kurane, 1993 #2152; Libraty, 2002 #2225}.
To understand the DENV-human host cell interaction at the molecular level, we performed global gene expression analysis on DENV-infected primary human cells using Affymetrix GeneChips (HG-U133A). We studied dendritic cells (DC), monocytes, B cells and human umbilical vein endothelial cells (HUVECs), all of which are known to be permissive to DENV infection. We first identified genes commonly regulated in multiple cell types in response to DENV infection; we hypothesized that understanding this common gene expression profile would identify signaling pathways involved in regulation of viral spread, activation of immune cells or induction of inflammation. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), one of the 23 common response genes, was identified as a key link between type I and type II interferon response genes. Pretreatment of cells with recombinant TRAIL (rTRAIL) inhibited DENV replication in monocytes, B cells, HUVECs and DCs. Using the DC infection model, we showed that this inhibition of viral replication was apoptosis-independent. Type-I IFN receptor (IFNR) blocking experiments showed that signaling through the type-I IFN receptor played an important role in the antiviral activity of exogenous rTRAIL. Furthermore, TRAIL also significantly reduced the expression of mRNA and protein of pro-inflammatory cytokines (TNFα, MIP-1β and IFNα) and chemokines (MCP-2, IP-10 and IL-6) in response to DENV infection. The data that TRAIL inhibits both viral replication and pro-inflammatory cytokine production suggest that TRAIL has therapeutic value in dengue.
The endothelial cell is the site of pathology in DENV infection in vivo (vascular permeability and plasma leakage). To understand the direct effect of DENV infection on endothelial cells and its role in the induction of genes regulating vascular permeability, we compared gene expression in DENV-infected HUVECs to that of uninfected cells and cells infected with other RNA and DNA viruses, including flaviviruses (West Nile, yellow fever, and Japanese encephalitis viruses), bunyaviruses (Sin Nombre and Hantaan viruses), Epstein-Barr virus and vaccinia virus. Among the genes confirmed for their differential expression, ST2 (Interkeukin-1 receptor-like-1 protein-IL1RL1) and indoleamine 2,3-dioxygenase (IDO) were identified to be upregulated specifically in response to DENV infection. Higher serum soluble ST2 (sST2) levels were detected in DENV-infected patients than in patients with other febrile illnesses (OFI) at the end of the febrile stage and at defervescence (p=0.0088 and p=0.0004, respectively). In addition, patients with secondary DENV infections had higher serum sST2 levels compared with patients with primary DENV infections (p=0.047 at the last day of fever and p=0.030 at defervescence). Higher levels of IDO activity (pIn conclusion, global gene expression analysis identified novel proteins with promising characteristics for the treatment and/or diagnosis of DENV infection. Although further studies will be needed to validate the clinical utility of TRAIL, sST2, and IDO, these studies demonstrate the utility of this unbiased genomics approach to identify therapies to currently incurable diseases.
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Levasseur, Stéphane. "Contribution à l'étude des phases Lix(Co,M)O2 en tant que matériaux d'électrode positive des batteries Li-ion : Effets combinés de la surstoechiométrie en lithium et de la substitution (M=Ni,Mg)." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2001. http://tel.archives-ouvertes.fr/tel-00003507.
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Des matériaux d'électrode positive pour batteries Li-ion de formule Lix0(Co,M)O2 (M = Ni, Mg ; x0 ≥ 1.0) ont été préparés à haute température (900° C) et caractérisés par diffraction des rayons X, tests galvanostatiques, spectroscopie de RMN MAS du 7Li et mesures électriques. Alors que les propriétés de la phase LiCoO2 sont en accord avec la littérature, dans tous les cas, l'ajout d'un excès de lithium lors de la synthèse conduit dans le matériau final à la présence d'un défaut structural constitué de lacunes d'oxygène et d'ions Co3+ spin intermédiaire (Co3+(IS)) en site pyramidal à base carrée. Ce défaut influe considérablement sur les propriétés des phases désintercalées puisqu'il supprime toutes les transitions de phase habituellement observées lors du cyclage galvanostatique de la phase LiCoO2. La substitution du nickel au cobalt permet de séparer la contribution des ions NiIII et Co3+(IS) quant à la disparition des transitions de phase lors de la désintercalation du lithium. La substitution du magnésium au cobalt, même sans excès de lithium, induit systématiquement la présence de ce type de défaut (Co3+(IS)). Cette particularité a été corrélée au comportement électrochimique de ces matériaux Lix(Co,Mg)O2 en cyclage.
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Das, Sanjit. "Methodological development in peptide chemistry for synthesis of antimicrobial and antifungal derivatives of marine natural peptides." Thesis, Perpignan, 2018. http://www.theses.fr/2018PERP0054.
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La chimie de clic est devenue indispensable dans les nombreux domaines de chimie associée à la conception de médicament. Dans ce contexte, comme nous savons(connaissons) l'étude concernant l'impact d'insertion triazole sur la conformation de peptaibol est limitée, nous avons conduit l'étude pour examiner l'impact et l'adaptabilité de 1, 1 4-disubstituted, 2, l'insertion 3-triazole dans peptaibols différent. Selon le résultat de cette expérience touchant à l'activité réduite et la conformation perturbée de l'analogue peptaibol, le substitut dipeptide décoré du fragment triazole portant substituents hydrophobe divers a été inséré à très N-ter la partie du peptaibol. L'amélioration du bioactivity et de la restauration de la conformation pour les analogues peptaibol a été observée et le fait a été aussi soutenu par les résultats obtenus de l'étude biophysique des analogues choisis d'ALM F50/5. Nous avons plus loin prolongé notre étude pour employer notre stratégie à être appliqué sur le peptide P42 thérapeutique qui souffre de la limitation de manque de perméabilité et de stabilité. Le peptide P42 est impliqué dans le pathophysiology de la maladie d'Huntington neurodégénératif. Un total de 12 analogues de peptide de P42-camelote a été synthétisé par SPPS par notre protocole optimize. Dans la deuxième partie, nous avons développé une stratégie pour synthétiser lipopeptide cyclique produit de l'espèce cynaobacterial marine. Notre objectif principal était de synthétiser Hormothamnin A, undecapeptide cyclique consistant de plusieurs acides aminés artificiels incluant dehydroamino acide (Dhaa) qui fait la synthèse de ce peptide compliqué. En raison de cette raison, premièrement, nous avons voulu appliquer notre stratégie de synthétiser Trichormamide A, une sorte relativement plus simple de cylic lipopeptide. Après l'accomplissement de cette tâche, une première tentative a été faite pour synthétiser Hormothamnin A. Le résultat préliminaire de ceci est présenté dans cette section. Enfin, nous avons essayé de développer une méthodologie robuste pour synthétiser Fmoc-Dhaa dans la phase de solution et son insertion dans l'ordre peptaibol par une norme(un standard) SPPS le protocole. Les résultats préliminaires que nous avons concernant la synthèse Dhaa et son insertion dans peptaibol sont aussi discutés ici de plus avec la synthèse de phase solide de Bergofungin naturel DThe click chemistry has become indispensible in the many areas of chemistry associated with drug design. In this context, as we know the study concerning the impact of triazole insertion on the conformation of peptaibol is limited, we have conducted the study to investigate the impact and adaptability of the 1, 4-disubstituted 1, 2, 3-triazole insertion into different peptaibols. Depending on the outcome of this experiment relating to reduced activity and perturbed conformation of the peptaibol analogue, the dipeptide surrogate decorated with the triazole moiety bearing various hydrophobic substituents was inserted at the very N-ter part of the peptaibol. The improvement of the bioactivity and restoration of the conformation for the peptaibol analogues was observed and the fact was also supported by the results obtained from the biophysical study of the selected analogues of ALM F50/5. We have further extended our study to employ our strategy to be applied on the therapeutic P42 peptide which suffers from the limitation of lack of permeability and stability. P42 peptide is involved in the pathophysiology of neurodegenerative Huntington’s disease. A total of 12 analogues of P42-TAT peptide were synthesized through SPPS by our optimized protocol. In the second part, we have developed a strategy for synthesizing the cyclic lipopeptide originated from marine cynaobacterial species. Our main objective was to synthesize Hormothamnin A, a cyclic undecapeptide consisting of several unnatural amino acids including dehydroamino acid (Dhaa) which makes the synthesis of this peptide complicated. Due to this reason, firstly, we have chosen to apply our strategy to synthesize Trichormamide A, a relatively simpler kind of cylic lipopeptide. After accomplishing this task, a first attempt was made to synthesize Hormothamnin A. The preliminary result of this is presented in this section. At last, we have tried to develop a robust methodology to synthesize Fmoc-Dhaa in solution phase and its insertion into the peptaibol sequence through a standard SPPS protocol. The preliminary results we have got concerning the Dhaa synthesis and its insertion into peptaibol are also discussed here in addition with the solid phase synthesis of natural Bergofungin D
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Drappier, Charlotte. "Auto-assemblages biofonctionnels à base de conjugués polymère-b-peptide." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00951878.
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La thèse présentée décrit la préparation et l'étude d'auto-assemblages élaborés à partir de conjugués amphiphiles Tat-b-poly(triméthylène carbonate) (Tat-b-PTMC) doués de propriétés d'internalisation cellulaire conférées par le segment peptidique Tat. L'objectif principal de ces travaux était d'établir et de comprendre les liens entre la structure macromoléculaire, les caractéristiques colloïdales et l'activité biologique de ces systèmes. Les efforts de précision moléculaire et de caractérisation fournispour la synthèse des chimères Tat-b-PTMC a permis de corréler finement leurs structures chimiquesaux paramètres physico-chimiques des nanoparticules obtenues. Grâce à une approche expérimentale transverse combinant des études de biologie cellulaire et de biophysique, le mécanisme d'interaction in vitro de ces nanoparticules avec les cellules HeLa a pu être en partie élucidé. Enfin, un camouflage électrostatique pH-sensible a été mis au point pour tenter de moduler leur activité et d'augmenter leur sélectivité vis-à-vis de l'environnement tumoral.
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Boidin, Rémi. "Etude des propriétés de conduction et structurales des verres du système Hgl₂-Ag₂S-As₂S₃ : application en tant que capteur chimique." Phd thesis, Université du Littoral Côte d'Opale, 2013. http://tel.archives-ouvertes.fr/tel-00958154.
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Les verres du système binaire Ag₂S-As₂S₃ sont connus pour être de très bons conducteurs ioniques et l'ajout de HgI₂ permet d'envisager une application des verres du pseudo-ternaire HgI₂-Ag₂S-As₂S₃ en tant que membrane ionique spécifique dédiée au dosage du mercure en solution aqueuse. Les limites de son domaine vitreux ont été vérifiées à l'aide de la diffraction des rayons X. Les évolutions des propriétés macroscopiques des verres, incluant les densités et les températures caractéristiques (Tg, Tc et Tf) ont été analysées de façon systématique. Les propriétés de conduction des verres HgI₂-Ag₂S-As₂S₃ ont été évaluées à l'aide de la spectroscopie d'impédance complexe et de la diffusion du traceur radioactif 108mAg. Un des résultats les plus marquants dans ces verres conducteurs ioniques est l'augmentation de la conductivité lorsque Ag₂S est substitué par HgI₂. Afin de comprendre les mécanismes de conduction mis en jeu, des études structurales ont été menées par spectroscopie Raman, diffusion de neutrons et diffraction des rayons X haute énergie. Pour appréhender la structure de ces verres complexes, des études préalables sur les deux systèmes pseudo-binaires Ag₂S-As₂S₃ et HgI₂-As₂S₃ ont aussi été menées. Les différentes techniques utilisées ont notamment permis de montrer que des réactions d'échanges se produisaient lors de la synthèse. Enfin, la dernière partie de cette thèse est entièrement consacrée à la caractérisation de nouveaux capteurs chimiques pour la détection des ions Hg²+ en solution. Différentes compositions sont testées afin de définir la sensibilité, la limite de détection et les coefficients de sélectivité en présence d'ions interférents.
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Fernandes, Mendonça Ana Catarina. "Simulations moléculaires d'une nouvelle classe de liquides ioniques basés sur la fonction ammonium pour l'utilisation potentielle en tant qu'huiles lubrifiantes respectueuses de l'environnement." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2013. http://tel.archives-ouvertes.fr/tel-00857336.
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L'objectif de ce travail est de comprendre la structure et les interactions des liquides ioniques au contact de surfaces métalliques à l'échelle moléculaire en ayant recours aux méthodes de dynamique moléculaire. Il s'agit également d'étudier l'impact de ces caractéristiques microscopiques sur les propriétés tribologiques du système. Les liquides ioniques choisis en tant qu'huiles lubrifiantes potentielles présentent des propriétés biodégradables et des caractéristiques tribologiques appropriées. Ils reposent sur des cations alkylammonium combinés avec des anions alkylsulfonate et bistriflamide. Notre étude est structurée en quatre parties. Elle commence par l'analyse des liquides ioniques purs puis, des liquides ioniques confinés entre deux surfaces de fer à l'équilibre et sous cisaillement, et enfin, en présence d'eau. Les propriétés structurales et dynamiques des liquides ioniques sont étudiées à travers la fonction de distribution radiale et les coefficients d'auto-diffusion. L'organisation des charges ainsi que la formation de micro-domaines en solution sont étudiées conjointement au comportement diffusif des espèces ioniques. Un champ de forces atomique, basé sur des méthodes quantiques, a été développé pour modéliser les interactions entre les liquides ioniques et la surface métallique. Des calculs DFT ont été réalisés sur des fragments de liquides ioniques en interaction avec un cluster de fer en fonction de la distance et de leur orientation. Une fonction modélisant des interactions site-site a été ajustée aux valeurs d'énergies fragment-cluster calculées par DFT afin d'obtenir les paramètres du champ de forces. Finalement, la polarisation du métal par les ions a été prise en compte en utilisant un modèle de dipôles induits afin de reproduire l'énergie d'interaction entre les charges et la surface conductrice. Avec ce modèle d'interaction, les simulations de dynamique moléculaire ont permis d'étudier la structure de l'interface entre une surface de fer plane et différents liquides ioniques. Cette analyse s'est concentrée sur l'étude du positionnement des différentes espèces au niveau de la surface, sur l'orientation des chaines alkyles et sur les profils de densité de charge. Des simulations de dynamique moléculaire hors-équilibre de liquides ioniques en interaction avec des surfaces de fer ont été réalisées en utilisant le champ de forces développé précédemment. Un protocole de simulation, basé sur une définition locale de la pression, a été développé pour prédire de manière quantitative le coefficient de friction en fonction de la valeur de la charge et du taux de cisaillement. La dépendance de la friction avec la charge, la vitesse de cisaillement, la topologie de la surface et la taille de la chaine alkyle du liquide ionique a été étudiée. La variation des forces de friction s'explique par l'arrangement spécifique des ions et l'orientation des groupements du liquide ionique à proximité de la surface. Finalement, l'effet de la présence d'eau en petite quantité dans une solution de liquide ionique a aussi été étudié à l'équilibre et hors-équilibre. Un potentiel a été construit pour décrire les interactions entre l'eau et une surface de fer en utilisant la même approche que celle décrite précédemment. Des résultats préliminaires concernant la structure de l'interface liquide-métal et la valeur du coefficient de friction ont été présentés et comparés avec ceux obtenus pour les liquides ioniques purs.
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Fenger, Julie-Anne. "Les anthocyanes acylées en tant que colorants naturels : réactivité en solution aqueuse, complexation métallique et stabilisation pour des applications alimentaires The chemical reactivity of anthocyanins and its consequences in food science and nutrition The influence of acylation and metal binding on the thermal stability of red cabbage anthocyanins The fate of acylated anthocyanins in neutral solution." Thesis, Avignon, 2020. http://www.theses.fr/2020AVIG0278.
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Les anthocyanes sont des pigments d’origine végétale exprimant des couleurs vives allant du rouge au bleu. Ce sont donc de bons candidats pour remplacer les colorants alimentaires artificiels. Cependant, leur faible stabilité est un frein à ces applications, tout particulièrement en milieu neutre requis pour l’expression de la couleur bleue. Une perspective prometteuse est le recours aux anthocyanes acylées par les acides phydroxycinnamiques, car ces pigments développent des mécanismes protecteurs de la couleur (copigmentation intramoléculaire, auto-association) basés sur de fortes interactions d’empilement entre le chromophore et les résidus acyl. Ce travail étudie donc les transformations structurales d’anthocyanes acylées (transferts de proton, addition d’eau), leur affinité pour les ions métalliques et leur stabilité au cours d’un traitement thermique. Dans ce but, des études cinétiques et thermodynamiques par spectroscopie UV-visible sont combinées à l’identification de produits de dégradation par UPLC-DAD/MS. L’impact des groupements acyl (nombre, position, type) a été étudié grâce à une gamme de pigments isolés du chou rouge et de la patate douce pourpre. Pour les premiers, les groupements acyl sur le sucre externe du groupement sophorose confèrent a) une protection optimale contre les attaques par H2O, H2O2 and SO32-, b) une plus grande affinité pour les ions métalliques, c) une plus grande stabilité thermique (pour les pigments et leurs complexes). En revanche, l’acide caféique, qu’il soit libre ou bien sous forme de résidu acyl (cas des anthocyanes de la patate douce violette), accélère la dégradation des anthocyanes, bien qu’il stabilise la couleur. Un traitement thermique modéré à pH 7 a converti les anthocyanes du chou rouge en acylsophoroses, phloroglucinaldéhyde-2-O-glucoside, acide protocatéchuique, dérivés de la 3,5,7-trihydroxycoumarine et de l’acide 2,4,6-trihydroxyphenylacétique. Un phénomène de migration intramoléculaire de résidus acyl a également été mis en évidence. La base anionique, une forme colorée majeure à pH 7, apparaît comme la plus vulnérable à l’autoxydation. Le peroxyde d’hydrogène ainsi formé est également impliqué dans la dégradation des anthocyanes. Globalement, nos résultats montrent que la forte association des anthocyanes acylées avec les ions du fer et de l’aluminium, voire l’ajout d’antioxydants naturels (par ex., la Nacétylcystéine), constituent des voies d’avenir pour le développement de colorants bleus naturels stablesAnthocyanins are ubiquitous plant pigments that exhibit bright colors from red to blue. Thus, they are good candidates to replace the synthetic food colors. However, the low stability of anthocyanin colors is a real hurdle to their industrial applications, especially under near neutral conditions required to express the blue color. A promising perspective is to resort to anthocyanins acylated by p-hydroxycinnamic acids, as these pigments develop colorstabilizing mechanisms (intramolecular copigmentation, self-association) based on strong stacking interactions between the anthocyanidin chromophore and the acyl residues. Therefore, this work investigates the structural transformations of acylated anthocyanins (proton transfer, water addition), their affinity to metal ions and their resistance to thermal degradation in the presence or absence of added metal ions. To that purpose, kinetic and thermodynamic studies by UV-visible spectroscopy are combined with the identification of degradation products by UPLC-DAD/MS. The impact of the acyl residues (number, location, type) was deciphered from a series of isolated pigments from red cabbage and purple sweet potato. With the former, the acyl residue bound to the external glucose of the sophorose moiety provides a) optimal protection against attacks by H2O, H2O2 and sulfite, b) improved affinity for metal ions, c) enhanced resistance against thermal degradation (for anthocyanins and their metal complexes). By contrast, caffeic acid, whether free or as an acyl residue (in purple sweet potato), accelerates the degradation of anthocyanins in spite of stabilizing the color. Under moderate heating at pH 7, red cabbage anthocyanins were degraded into acylsophoroses, phloroglucinaldehyde-2-O-glucoside, protocatechuic acid, 3,5,7trihydroxycoumarin derivatives, and 2,4,6-trihydroxyphenylacetic acid derivatives. Intramolecular acyl migration was also evidenced. The anionic base, a major colored form at pH 7, appears most vulnerable to autoxidation. The hydrogen peroxide thus produced is further involved in anthocyanin degradation. Overall, the tight binding of acylated anthocyanins to iron and aluminum ions and possibly the addition of natural antioxidants (e.g., N-acetylcysteine) are promising perspectives for the development of stable natural blue colors
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George, Nicolas. "Étude de la synthèse totale de tétrahydroisoquinoléines naturelles : quinocarcine, Tétrazomine et Lémonomycine. : rapide accés aux α-amidosulfures et leur utilisation en tant que précurseurs de N-acylimines dans la réaction de Friedel-Crafts." Phd thesis, Université Paris Sud - Paris XI, 2011. http://tel.archives-ouvertes.fr/tel-00980348.
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La quinocarcine, la tétrazomine et la lémonomycine constituent une sous-famille appartenant à la famille des tétrahydroisquinoléines trisubstituées naturelles. Ce sont des puissants agents cytotoxiques et possèdent de nombreuses activités biologiques telles qu'antitumorales et antibiotiques. Leur complexité structurale, leurs intérêts biologiques ainsi que leur faible rendement d'extraction du milieu naturel font de ces molécules des cibles attrayantes pour les chimistes de synthèse.Ces trois molécules sont constituées d'une tétrahydroisoquinoléine différemment substitué fusionnée avec un diazabicycle[3.2.1]octane commun. Le but de ce projet était de mettre au point une stratégie commune à cette sous-famille et divergente grâce à la synthèse du diazabicyclooctane en premier. Une première stratégie faisant intervenir une aziridine n'a pas permis de construire le bicycle. Cet objectif a été réalisé grâce à une seconde stratégie. Elle repose sur une première cyclisation d'un hémiaminal puis d'une cyclisation par addition nucléophile d'un éther d'énol silylé sur un N-acylimmonium formé in situ au départ d'un N,S-acétal.Parallèlement à cette étude synthétique, nous avons mis au point une réaction multicomposant séquentielle qui permet l'accès rapide et général aux a-amidosulfures, comblant un manque dans la littérature. Ensuite nous avons étudié la réactivité de ces composés en tant que précurseurs simples de N-acylimines en conditions acides douces. Trois conditions réactionnelles, nous ont permis d'accéder à cette objectif : l'utilisation stœchiométrique d'acétate d'argent, catalytique d'acide phosphorique ainsi que le NIS en quantité stœchiométrique et catalytique. Cette dernière réaction est très attrayante. En effet, ce réactif doux et neutre permet l'élimination efficace du thiol formant la N-acylimine puis son activation pour se faire piéger in situ par un nucléophile. Les rendements atteints sont très hauts en moins de 5 minutes.
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Pucik, Lara Ellen. "The behavior of TNT in model chemical redox systems and the fate of TNT reduction products in aerobic microbial systems." Thesis, 1996. http://hdl.handle.net/1911/14075.
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When exposed to the Fenton oxidation process, approximately 25% of the initial TNT was mineralized and approximately 63% was converted to unknown soluble products. When exposed to Fe(0) under acidic conditions, TNT was completely reduced to unknown products, approximately 20% of which were not soluble. Reduction of TNT by Fe(0) did not occur above pH 3.0. When exposed to sulfide, TNT was reduced to a mixture of 4ADNT, 2ADNT, DA6NT and unknown soluble products. TNT and its reduction products from chemical (iron and sulfide), aquatic plant, and Clostridia systems were not mineralized by either an activated sludge culture or a mixed aerobic culture grown on anthranilic acid. Biological transformation of TNT and sulfide-reduced TNT products, however, did appear to occur in the aerobic microbial culture grown on anthranilic acid.
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Gallagher, Erin Maureen. "Anaerobic degradation of 2,4,6- trinitrotoluene (TNT) molecular analysis of active degraders and metabolic pathways /." 2010. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.000052111.
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Lauritzen, John Robert III. "Catharanthus roseus as a model system for the study of the phytoremediation of TNT." Thesis, 1998. http://hdl.handle.net/1911/17191.
Full textAbstract:
C. roseus hairy roots cultures were employed to prove the ability of plants to take up and transform TNT in the absence of microbes. Mass balances performed with 14C-TNT showed that the TNT was being taken up and transformed and not mineralized. The transformation pathway was seen to be at least initially reductive. However, in cases where no TNT was detectable at experiment's end, standards could only account for 5% of the final products. Pseudo-first order reaction kinetics were observed for low initial concentrations of TNT in both stationary and exponential phase hairy root cultures. Kinetic constants ranged from 0.0103 to 0.0161 L/g-day for stationary phase experiments performed with 15 to 35 mg/L initial TNT concentrations. Kinetic constants of 0.0075 to 0.0156 L/g-day were observed for experiments performed on exponential growth phase hairy roots with an initial TNT concentration of 20 to 40 mg/L. Toxic effects were seen at all phases of growth and all concentrations measured.
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(10732050), Patrick D. Bowers. "Direct-Write of Melt-Castable Energetic and Mock materials." Thesis, 2021.
Find full textAbstract:
Explosives and rocket fuel are just two prime examples of energetic materials, compounds that contain a combustible fuel and oxidizer within the same substance. Recent advances have enabled the construction of energetic materials through multiple variations of additive manufacturing, principally inkjet, direct-write, fused filament fabrication, electrospray deposition, and stereolithography. Many of the methods used for creating multiple layered objects (three-dimensional) from energetic materials involve the use of highly viscid materials.
The focus of this work was to design a process capable of additively manufacturing three-dimensional objects from melt-castable energetic materials, which are known for their low viscosity. An in-depth printer design and fabrication procedure details the process requirements discovered through previous works, and the adaptations available and used to construct an additive manufacturing device capable of printing both energetic and non-energetic (also referred to as inert) melt-castable materials. Initial characterization of three proposed inert materials confirmed their relative similarity in rheological properties to melt-castable energetic materials and were used to test the printer’s performance.
Preliminary tests show the constructed device is capable of additively manufacturing melt-castable materials reproducibly in individual layers, with some initial successful prints in three-dimensions, up to three layers. An initial characterization of the printer’s deposition characteristics additionally matches literature predictions. With the ability to print three-dimensional objects from melt-castable materials confirmed, future work will focus on the reproducibility of multi-layered objects and the refined formulation of melt-castable energetic materials.
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Kitts, Kelley M. "Evaluation of Odor Compounds Sensed by Explosives-Detecting Canines." 2013. http://hdl.handle.net/1805/3415.
Full textAbstract:
Indiana University-Purdue University Indianapolis (IUPUI)Canines are regularly utilized by law enforcement agencies to detect explosives. However, the mechanism by which canines respond to explosive vapors is not well understood, leading to difficulties in canine training and testing. It is known that the amount of vapor generated from explosive compounds is dependent upon several factors including sample amount, vapor pressure, and the degree of confinement. Underlying these factors is the basic process of evaporation of an unconfined explosive, which is rucial to understanding how explosive vapors behave in other, more confined, systems. In Stage One of this study, evaporation rates were determined for several explosive liquids using an analytical balance. These rates were compared to one another as well as to theoretical models for the evaporation of liquids. In general and as expected, mass decreased linearly with time and evaporation rates decreased logarithmically as boiling point increased. Several examples of solvent “pinning” on a metal surface were also observed. While an empirical model for the evaporation of unconfined explosive liquids was developed, a comprehensive model for the escape of explosive vapors from sealed containers (i.e., a suitcase, knapsack, or IED container itself) is needed. The second part of Stage One of this study was to determine that the flow rate of explosive vapors escaping from relatively large orifices does not conform to Fick’s Law of Diffusion. Fick’s model states that the flow rate is linearly dependent upon the cross sectional area of the orifice and the material’s diffusion coefficient. Instead, the flow rate was found to be linearly dependent upon the diameter of the orifice due to the tendency of the flow to diffuse outwards from its circular edge. A clear relationship between flow rate and diffusion coefficient was seen, however. Additional uncertainty arises concerning the complexity of the odor generated from explosive compounds. Because explosive vapors are often complex (they consist of multiple chemical compounds), confusion exists regarding the cause of canine alert; that is the “odor compound” that allows for canine detection of various explosives. Although 2, 4- dinitrotoluene (DNT) has been explored as a potential odor compound, the possibility of a nitrated explosive inherently producing nitrated gas upon decomposition has not. Stage Two of this study focused on evaluating nitrate as a potential cause of canine alerts. An LC/MS method for the detection of nitrate ions in Composition C-4 and flake trinitrotoluene (TNT) was developed and tested. Instrumental analysis was not successful in detecting nitrate ions in any of the explosives tested. The lack of nitrate was confirmed using a diphenylamine color test for nitrates, thus eliminating nitrate as an odor compound and cause of canine alert to nitroaromatic compounds. 2, 4-DNT has been introduced as a potential odor compound of TNT, however, the mechanisms behind its vapor emission have not been thoroughly explored. More specifically, due to the “sticky” nature of the 2, 4-DNT isomer, the effects of surface adhesion to container walls are of concern. In particular, whether the amount of material lost to surface adhesion is significant enough to effect canine detection of TNT. A second focus of Stage Two explored this concern. A GC/MS method for the detection and separation of TNT and DNT isomers in liquid extracts was developed and the amount of 2, 4-DNT residues adhering to container walls was quantified. These values, compared to the amount 2,4-DNT expected to saturate each container (determined by the Ideal Gas Law), showed a significant preference of 2,4-DNT in the solid phase as opposed to in the gas phase. The amount of residue adhering to the walls of a gallon can differed from expected values by nearly 70%. The amount of material extracted from a quart can exceeded expected values by 137%. The apparent sticky nature of 2, 4-DNT resulted in a significant loss of material needed to fully saturate a container and thus canine detection success may be affected. In the final stage of this study, theories regarding odor compounds and odor availability of nitromethane, TNT, and Composition C-4 were tested using certified explosives-detecting canines. These trials included thirty-three canine-handler teams from eight government agencies. The odor availability of nitromethane was tested by placing varying volumes of nitromethane in containers with differing degrees of confinement and studying the effects on canine detection success. The odor availability trial showed no significant effect of sample amount or degree of confinement on canine detection so long as the sample volume was sufficient to saturate its container. In this study that volume was determined to be < 1 mL. Detection of 2, 4-DNT, TNT-NESST (Non-Hazardous Explosives for Security Training and Testing), and flake TNT were also studied using certified canines. The purpose of this was to identify the odorant responsible for canine alert to the explosive TNT. These trials showed a significant response to 2, 4-DNT compared to TNT and its training aid; this suggests that 2, 4-DNT is the primary cause of canine alerts to TNT. Additionally, Composition C-4 and RDX-NESTT were tested along with potential odor compounds that included the manufacturing solvent, cyclohexanone, the energetic “taggant” 2, 3-dimethyl-2.3-dinitrobutane (DMNB), the plasticizer dioctyladipate (DOA) and its degradation product 2-ethyl-1-hexanol. While some response to DMNB and cyclohexanone was seen, the most significant response was to the actual Composition C-4. This suggests that the cause of canine alert to Composition C-4 is the explosive mixture as a whole and not a single chemical component of the mixture
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Yang, SHIH-FENG, and 楊世豐. "TFT LCD Dry etcher process chemical type Side etch study." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/19184604902928332763.
Full textAbstract:
碩士國立交通大學
平面顯示技術碩士學位學程
102
During TFT-LCD array process, etching plays a crucial role of creating designed circuits and patterns. By applying chemical or physical process etching can remove certain parts of the deposit film which are not protected by the photo resist. Therefore it can transfer specific patterns from the photo mask to the deposit film (usually thousands of Å) on the glass. The transferred circuit and patterns are important components in the TFT-LCD manufacturing process. Currently there are two types of etching techniques in TFT LCD etching process, Wet and Dry Etching. The former applies chemical agent while the later takes the physical reaction approach (via plasma); In practice one can fine tune some parameters to change dry etching to behave like chemical type. Conventional results show Wet etching is superior in terms of factory throughput. However its isotropic etching by chemical agent may cause undercut issue, which makes line width hard to control. To the contrary although Dry Etching has lower throughput that is introduced by vacuuming process. Its anisotropic property makes it a great method when line width quality is a top priority. The focus of this dissertation is on Dry Etching. We will show by fine tuning some dry etching parameters to make it similar to wet etching, one can achieve the benefit of both wet and dry etching, i.e. higher throughput and better line width control (less occurrence of defects). This paper applied the methodology of Evidence Act and Taguchi experimental method to research the genuine parameters that make Dry Etching process act similar to the wet one. We filtered the candidate parameters and searched for the optimized parameter set in the experiments. We hope the study results can improve existing dry etching process recipe and eventually this new concept can be introduced in the mass-production manufacturing process.
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Su, Teng-fu, and 蘇登福. "Treatment of TFT-LCD fluoride-containing wastewater by chemical precipitation." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/18143607015888221852.
Full textAbstract:
碩士國立中央大學
環境工程研究所碩士在職專班
99
This study investigated the effectiveness of fluoride removal from TFT-LCD fluoride-containing wastewater by chemical precipitation with CaO or CaCl2 as calcium salt. The effects of calcium dosage and pH on fluoride removal were evaluated by the laboratory jar tests. Additionally, the feasibility of enhancing fluoride removal by the aid of coagulant or polymer addition was investigated. Finally, the characteristics of fluoride containing sludge and its properties of thickening and dewatering were also evaluated based on the real samples obtained from full-scale treatment plant. The investigation results indicated that the pH of fluoride containing wastewater was less than 3.9 and the fluoride concentration was in the range of 94mg/L to 221 mg/L. The titration curve of the wastewater neutralized by NaOH revealed that the wastewater property was strong acidic. The jar test results showed that up to 77% of fluoride removal was obtained as fluoride precipitated by CaO at the dosage of Ca/F ratio was 1.4. However, using CaCl2 as precipitant at Ca/F ratio was 1.4 and pH was between 7 and 8, the fluoride removal efficiency was up to 95%. The experimental results also revealed that adding coagulant of PACl with calcium salt during chemical precipitation could further increase the removal efficiency of fluoride ion. Moreover, adding coagulant aid of polymer did not enhance the efficiency of fluoride removal, but could improve the floc formation and increased its settleability. The study also found that chemical conditioning of fluoride-containing sludge by polymer, especially nonionic polymer, could significantly improve the dewaterability of the sludge. This was verified by the reduction of SRF and CST values after sludge conditioning.
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Lin, Chien-Chung, and 林建忠. "Research on Uniformity Improvement for chemical vapor deposition in TFT-LCD." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/apjdtq.
Full textAbstract:
碩士國立交通大學
平面顯示技術碩士學位學程
102
In this thesis, we discussed with the characteristics of amorphous Silicon (a-Si) thin film deposition in PECVD equipment by different process conditions. Four input parameters (RF power, chamber pressure, the upper electrode plate holes, upper and lower electrode plate spacing) and two output variables (deposition thickness and uniformity) are selected to establish thin film deposition model. Different data were applied to input parameters, and used experimental design of all factor concept to seek the relationship between four input parameters and two output variables. The thin film deposition model was created by using Taguchi method for experimental analysis, and this test method is supported by experiments conducted system parameter optimization process. Taguchi method is used to improve quality engineering methods also known as robust design for quality improvement methods to minimize the sensitivity to the surrounding environmental impact. Simulation and experiments verified that the desired output parameters reached the target value. The uniformity of a-Si thin-film layer is improved from 16.27% to 7.85%, which also provided better yield rate.
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Kang, Ren, and 刁仁康. "Evaluation of Phosphate-containing Wastewater Treated by Chemical Coagulation Process in TFT-LCD Plant." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/61613590797865110265.
Full textAbstract:
碩士國立中央大學
環境工程研究所碩士在職專班
100
The wastewater treatment system, installed at a 6th generation of TFT-LCD manufacturing plant, was designed to meet the goal of reaching 90 % process water recovery and 85 % total water recovery. The high percentage of water recovery resulted in losing the dilution efficiency, thus, the effluent phosphorous concentration was much higher compared with the effluent qualities discharged by similar industry. According to the investigation of phosphorous distribution in various sources of this case plant, it found that there are two major sources of phosphate containing wastewater. One is directly discharge from cleaning process of Al-etching. The other is RO reject (ROR) in which the RO system followed on the anoxic/aerobic coupled with membrane filtration (A/O MBR) process for treating the mixture of raw wastewater from cleaning process of Al-etching and low organic concentration wastewater from other manufacturing processes. This study intent to investigate the optimum operation conditions for removing the phosphate from the above two sources of wastewater by chemical coagulation jar test using calcium chloride, aluminum chloride, and ferrous chloride as coagulant, respectively. The experimental results revealed that the optimum operating conditions were: (1) pH value was 8 and Ca/P dosage ratio was 2 for calcium chloride; (2) pH value was 5 and Al/P dosage ratio was 1.4 for aluminum chloride; and (3) pH value was 6 and Fe/P dosage ratio was 1.8 for ferrous chloride. The optimum results obtained in this study were fully agreeing with the past studies for aluminum chloride and ferrous chloride as coagulant. However, the phosphate removal efficiency was decreased as the pH value was greater than 9 for calcium chloride as coagulant in this study. This result was completely disagreeing with using lime as common coagulant which the best phosphate removal efficiency generally occurs at pH was above 10. Based on the comparative evaluation of chemical cost and operating condition for the three coagulants, it suggests that calcium chloride is the proper coagulant for removing phosphate in the case plant. Comparing the chemical cost and waste sludge treatment cost for treating these two phosphate containing wastewater streams, there are insignificant differences for installing chemical coagulation process at either site of wastewater source. However, the wastewater from cleaning process of Al-etching after pretreatment by chemical coagulation, its water qualities may cause clogging of the RO membrane and decreasing the benefits for water recycle and reuse. Meanwhile, the construction cost of chemical coagulation process for phosphate removal from Al-etching wastewater was high. Consequently, the better location for phosphate removal by chemical coagulation process in this case plant should focus on ROR stream.