To see the other types of publications on this topic, follow the link: Chemical compound.
Dissertations / Theses on the topic 'Chemical compound'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Chemical compound.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Zhu, Ya. "Chemical Compound Classification Ensemble." Thesis, North Dakota State University, 2013. https://hdl.handle.net/10365/27059.
Full textAbstract:
Document incorrectly classified as a dissertation on title page (decision to classify as a thesis from NDSU Graduate School)In the research of health science, scientists often need to screen numerous chemical compounds to find drugs that can treat a disease. The process of testing the functionality of these compounds in the laboratory is very time-consuming. Computational methods have been used to accelerate this process. These computational methods are implemented based on the principle that chemical compounds with similar structure often have similar function. Thus, these methods maintain a database of chemical compounds whose function has been verified using laboratory experiments. The database contains the chemical structural formula of a compound, the 3D coordinate of every atom, and whether it has a certain function, e.g. it can kill a virus. Then, for a new compound, the programs compare its structure with those in the database and predict if it has the function based on the structure similarity. Thus, predicting the function of a compound is a two-class classification problem. In this project, we try to address this two-class classification problem using global and local similarity between compounds. The global similarity measures the overall structural resemblance between two compounds. When a group of compounds have the same function, they usually share some common sub-structures. These common sub-structures may correspond to their functional sites. Local similarity is computed based on the occurrences of common sub-structures between compounds. We built several classification models based on global and local similarity. To improve the classification result, we used an ensemble of those models to predict the function compounds in NCI cancer data sets. We predict whether a compound can inhibit cancer cell growth or not, obtaining AUC higher than 80% for five datasets. We compare our results with other state-of-the-art methods. Our classification result is the best in all five datasets. Our results show that local similarity is more useful than global similarity in predicting compound function. An ensemble method integrating global and local similarity achieves much better performance than single predicting models.
2
Tsamopoulos, John Abraham. "Nonlinear dynamics of simple and compound drops." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/119604.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE.
Bibliography: leaves 176-186.
by John Abraham Tsamopoulos.
Ph.D.
3
Wang, Hao. "Design of a Structure Search Engine for Chemical Compound Database." Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/cs_diss/33.
Full textAbstract:
The search for structural fragments (substructures) of compounds is very important in medicinal chemistry, QSAR, spectroscopy, and many other fields. In the last decade, with the development of hardware and evolution of database technologies, more and more chemical compound database applications have been developed along with interfaces of searching for targets based on user input. Due to the algorithmic complexity of structure comparison, essentially a graph isomorphism problem, the current applications mainly work by the approximation of the comparison problem based on certain chemical perceptions and their search interfaces are often e-mail based. The procedure of approximation usually invokes subjective assumption. Therefore, the accuracy of the search is undermined, which may not be acceptable for researchers because in a time-consuming drug design, accuracy is always the first priority. In this dissertation, a design of a search engine for chemical compound database is presented.The design focuses on providing a solution to develop an accurate and fast search engine without sacrificing performance. The solution is comprehensive in a way that a series of related problems were addressed throughout the dissertation with proposed methods. Based on the design, a flexible computing model working for compound search engine can be established and the model can be easily applied to other applications as well. To verify the solution in a practical manner, an implementation based on the presented solution was developed. The implementation clarifies the coupling between theoretic design and technique development. In addition, a workable implementation can be deployed to test the efficiency and effectiveness of the design under variant of experimental data.
4
McDaniel, Eric B. "Organophosphorus Compound Detection Using Enzyme Encapsulated in Peptide Nanotubes." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1384526146.
Full text
5
Castro, Joseph Emmanuel 1962. "Model compound interactions characterizing aquatic humic substances." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277256.
Full textAbstract:
An attempt was made to simulate XAD-8 isolates of Orange County groundwater and Biscayne Aquifer groundwater using mixtures of single ligands. Mixtures of catechol, glycine, phthalic acid and salicylic acid were used to simulate potentiometric and complexometric titrations. Concentrations used for the mixtures were based on carboxylic acidity, dissolved organic carbon, and assumed values for phenolic acidity and nitrogen content. Potentiometric titrations were reproduced with mixtures of the ligands; however, complexometric titrations at pH 6.2 and pH 7.5 could not be duplicated. A stronger ligand was required to fit the pH 6.2 titrations, and higher carboxylic contents were needed for pH 7.5. At pH 6.2 70 percent of the binding sites were attributed to phthalic acid-type groups and 20 percent to catechol-type groups. At pH 7.5 greater than 98 percent was attributed to phthalic acid-type groups.
6
Yahya, Faridah Binti. "Extraction of aroma compound from Pandan leaf and use of the compound to enhance rice flavour." Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3773/.
Full textAbstract:
Supercritical carbon dioxide (SC-CO\(_2\)) and Soxhlet extraction using hexane as solvent were used to extract 2-acetyl-1-pyrroline (2-AP) from Pandan leaves. The effect of different extraction pre-treatments, such as particle size and drying on the extraction yield and concentration of 2-AP were investigated. The identification and quantification of 2-AP were carried out by gas chromatography-mass spectrometry and gas chromatography-flame ionization detector, respectively. This work aims to provide an understanding of the phenomena that occur during cooking and storage; typically on the changes of 2-AP absorption when cooking rice grains with Pandan leaves. The parameters investigated were cooking method of excess and optimal water conditions. Even though low in yield, and the 2-AP concentration was obtained from supercritical carbon dioxide extraction, the extracts were pure without any contamination. The grinding and freeze-drying method revealed the best pre-treatments for supercritical extraction. The absorption of 2-AP during the cooking of rice grains did not smoothly increase with time. This unexpected result indicated that the phenomena occurring during cooking are quite complex. This work also quantified the potential of Pandan leaves to enhance the flavour of cooked rice, particularly under excess water conditions. Storage for 15 min at 24.0 \(\pm\)1.0\( \circ\)C is considered as the optimum time for obtaining cooked rice with a high quality of flavour.
7
Kotsiopoulos, Athanasios. "The hydrocracking of Fischer-Tropsch wax : using n-tetradecane as a model compound." Master's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/8662.
Full textAbstract:
Includes bibliographical references (p. 99-102).Increasingly stringent legislation has been applied to transportation fuels to minimise or eliminate aromatics and sulphur compounds in diesel fuel. This has led to manufacturers determining alternative production methods to comply to legislation. Part of the current diesel fuel is being produced by hydrocracking heavier fractions derived from crude oil. These hydrocracking processes utilise bi-functional catalysts which have a metal (hydrogenating/dehydrogenating) function and an acid (cracking) function. The most common of these hydrocracking catalysts are combinations of either noble metals and acid zeolites, such as Pt/ HY, or combined sulphides of group VIA and VIIIA metals on amorphous acidic supports, such as CoMo/SiO2-Al2O3. For good quality diesel, the fuel should have a high cetane number and the aromatics and sulphur content should also be kept to a. minimum (e.g. EU legislation: sulphur content must be below 10 ppm (wt) by 2008). Fischer-Tropsch wax is made up predominantly of long-chain linear paraffins with exceptionally low aromatics and heteroatom content (sulphur and nitrogen-containing compounds) and therefore a good source for very 'clean', good quality diesel. The objective of this study was therefore to investigate the suitability of a conventional bi-functional hydrocracking catalyst namely, CoMo/SiO2-Al2O3 in unsulphided form for the hydrocracking of Fischer-Tropsch wax using n-tetradecane as a model compound. The purpose of using the catalyst in unsulphided form was not to introduce any sulphur to the already sulphur-free feedstock.
8
Fenwick, William Edward. "Metalorganic chemical vapor deposition of gallium nitride on sacrificial substrates." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/34687.
Full textAbstract:
GaN-based light emitting diodes (LEDs) face several challenges if the technology is to make a significant impact on the solid state lighting market. The two most pressing of these challenges are cost and efficiency. The development of alternative substrate technologies shows promise toward addressing both of these challenges, as both GaN-based device technology and the associated metalorganic chemical vapor deposition (MOCVD) technology are already relatively mature. Zinc oxide (ZnO) and silicon (Si) are among the most promising alternative substrates for GaN epitaxy. This work focuses on the development of MOCVD growth processes to yield high quality GaN-based materials and devices on ZnO and Si.
ZnO, because of its similar lattice constant and thermal expansion coefficient, is a promising substrate for growth of low defect-density GaN. The major hurdles for GaN growth on ZnO are the instability of ZnO in a hydrogen atmosphere and out-diffusion of zinc and oxygen from the substrate. A process was developed for the MOCVD growth of wurtzite GaN and InxGa1-xN on ZnO, and the structural and optical properties of these films were studied. High zinc and oxygen concentrations remained an issue, however, and the diffusion of zinc and oxygen into the subsequent GaN layer was studied more closely.
Silicon is the most promising material for the development of an inexpensive, large-area substrate technology. The challenge in GaN growth on Si is the tensile strain induced by the lattice and thermal mismatch between GaN and Si. A thin atomic layer deposition (ALD)-grown Al2O3 interlayer was employed to relieve strain while also simplifying the growth process. While some strain was still observed, the oxide interlayer leads to an improvement in thin film quality and a reduction in both crack density and screw dislocation density in the GaN films.
A comparison of GaN-based LEDs grown on sapphire and Al2O3/Si shows similar performance characteristics for both devices. IQE of the devices on silicon is ~32%, compared to ~37% on sapphire. These results show great promise toward an inexpensive, large-area, silicon-based substrate technology for MOCVD growth of GaN-based optoelectronic devices.
9
Gopal, Madan. "Microwave enhanced chemical vapor deposition of silicon compound thin films and their characterization." Ohio : Ohio University, 1991. http://www.ohiolink.edu/etd/view.cgi?ohiou1183728633.
Full text
10
Kanekal, Kiran H. [Verfasser]. "Investigating the Effect of Coarse-Graining on Chemical Compound Space / Kiran H. Kanekal." Mainz : Universitätsbibliothek der Johannes Gutenberg-Universität Mainz, 2021. http://d-nb.info/1231433515/34.
Full text
11
Jira, Jindalertudomdee. "Chemical Compound Enumeration and Host-Pathogen Protein Interaction Prediction by Graph-Based Approaches." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/217198.
Full text
12
Vankova, Viera. "Metalorganic vapour phase epitaxial growth and characterisation of Sb-based semiconductors." Thesis, Nelson Mandela Metropolitan University, 2005. http://hdl.handle.net/10948/d1019678.
Full textAbstract:
This study focuses on the growth and characterization of epitaxial InAs and InAs1-xSbx. Layers are grown on InAs, GaAs and GaSb substrates by metalorganic vapour phase epitaxy, using trimethylindium, trimethylantimony and arsine as precursors. The growth parameters (V/III ratio, Sb vapour phase compositions) are varied in the temperature range from 500 ºC to 700 ºC, in order to study the influence of these parameters on the structural, optical and electrical properties of the materials. The layers were assessed by X-ray diffraction, electron and optical microscopy, photoluminescence and Hall measurements. Furthermore, the influence of hydrogenation and annealing on the electrical and optical properties of GaSb was investigated. It is shown that the growth temperature and the V/III ratio play a vital role in the resulting surface morphology of homoepitaxial and heteroepitaxial InAs layers. Growth at low temperatures is found to promote three-dimensional growth in both cases, with improvements in the surface morphologies observed for higher growth temperatures. All the investigated epilayers are n-type. It is shown that the electrical properties of heteroepitaxial InAs epilayers are complicated by a competition between bulk conduction and conduction due to a surface accumulation and an interface layer. The low temperature photoluminescence spectra of homoepitaxial InAs are dominated by two transitions. These are identified as band-to-band/excitonic and donor-acceptor recombination. The incorporation efficiency of antimony (Sb) into InAs1-xSbx is dependent on the growth temperature and the V/III ratio. Under the growth conditions used in this study, the incorporation efficiency of Sb is controlled by the thermal stability of the two constituent binaries (i.e. InAs and InSb). Changes in the low temperature photoluminescence spectra are detected with increasing x. From temperature and laser power dependent measurements, the highest energy line is attributed to band-to-band/excitonic recombination, while the peak appearing approximately 15 meV below this line is assigned to donor-acceptor recombination. The origin of an additional “moving” peak observed for higher Sb mole fraction x is tentatively attributed to quasi-donor-acceptor-recombination, arising from increased impurity/defect concentrations and a higher compensation ratio in the material. However, the unusual behaviour of this peak may also be ascribed to the presence of some degree of ordering in InAsSb. The exposure of a semiconductor to a hydrogen plasma usually leads to the passivation of shallow and deep centres, thereby removing their electrical and optical activity. In this study, the passivation and thermal stability of the native acceptor in p-type GaSb is also investigated. It is shown that this acceptor can be passivated, where after improvements in the electrical and optical properties of GaSb are observed. Upon annealing the passivated samples above 300 °C, the acceptor is reactivated.
13
Beltz, Katylynn. "The Development of Calibrants through Characterization of Volatile Organic Compounds from Peroxide Based Explosives and a Non-target Chemical Calibration Compound." FIU Digital Commons, 2013. http://digitalcommons.fiu.edu/etd/817.
Full textAbstract:
Detection canines represent the fastest and most versatile means of illicit material detection. This research endeavor in its most simplistic form is the improvement of detection canines through training, training aids, and calibration. This study focuses on developing a universal calibration compound for which all detection canines, regardless of detection substance, can be tested daily to ensure that they are working with acceptable parameters. Surrogate continuation aids (SCAs) were developed for peroxide based explosives along with the validation of the SCAs already developed within the International Forensic Research Institute (IFRI) prototype surrogate explosives kit. Storage parameters of the SCAs were evaluated to give recommendations to the detection canine community on the best possible training aid storage solution that minimizes the likelihood of contamination. Two commonly used and accepted detection canine imprinting methods were also evaluated for the speed in which the canine is trained and their reliability.
As a result of the completion of this study, SCAs have been developed for explosive detection canine use covering: peroxide based explosives, TNT based explosives, nitroglycerin based explosives, tagged explosives, plasticized explosives, and smokeless powders. Through the use of these surrogate continuation aids a more uniform and reliable system of training can be implemented in the field than is currently used today. By examining the storage parameters of the SCAs, an ideal storage system has been developed using three levels of containment for the reduction of possible contamination. The developed calibration compound will ease the growing concerns over the legality and reliability of detection canine use by detailing the daily working parameters of the canine, allowing for Daubert rules of evidence admissibility to be applied. Through canine field testing, it has been shown that the IFRI SCAs outperform other commercially available training aids on the market. Additionally, of the imprinting methods tested, no difference was found in the speed in which the canines are trained or their reliability to detect illicit materials. Therefore, if the recommendations discovered in this study are followed, the detection canine community will greatly benefit through the use of scientifically validated training techniques and training aids.
14
Kang, Byoung Sam. "Fabrication and characterization of compound semiconductor sensors for pressure, gas, chemical, and biomaterial sensing." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0012990.
Full text
15
Whiteley, Clinton E. "Advanced crystal growth techniques with III-V boron compound semiconductors." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/8110.
Full textAbstract:
Doctor of PhilosophyDepartment of Chemical Engineering
James H. Edgar
Semiconducting icosahedral boron arsenide, B[subscript]12As[subscript]2, is an excellent candidate for neutron detectors and radioisotope batteries, for which high quality single crystals are required. Thus, the present study was undertaken to grow B[subscript]12As[subscript]2 crystals by precipitation from metal solutions (nickel) saturated with elemental boron and arsenic in a sealed quartz ampoule. B[subscript]12As[subscript]2 crystals of 8-10 mm were produced when a homogeneous mixture of the three elements was held at 1150 °C for 48-72 hours and slowly cooled (3°C/hr). The crystals varied in color and transparency from black and opaque to clear and transparent. X-ray topography (XRT), Raman spectroscopy, and defect selective etching confirmed that the crystals had the expected rhombohedral structure and a low density of defects (5x10[superscript]7 cm[superscript]-2). The concentrations of residual impurities (nickel, carbon, etc) were found to be relatively high (10[superscript]19 cm[superscript]-3 for carbon) as measured by secondary ion mass spectrometry (SIMS) and elemental analysis by energy dispersive x-ray spectroscopy (EDS). The boron arsenide crystals were found to have favorable electrical properties (μ = 24.5 cm[superscript]2 / Vs), but no interaction between a prototype detector and an alpha particle bombardment was observed. Thus, the flux growth method is viable for growing large B[subscript]12As[subscript]2 crystals, but the impurity concentrations remain a problem.
16
Karlsson, Oskar. "Ferulic Acid – A Valuable Natural Compound for Sustainable Materials." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-290233.
Full textAbstract:
One of the largest problems that stands before us is the quest to find sustainable alternatives to fossil-based materials. Fossil-based products can be found all around us in our society. This quest has forced us to look for new ways to build materials. Synthetic polymer materials have traditionally been produced from fossil-based starting materials however, in modern times studies regarding biobased superseders for the unsustainable starting materials has been conducted. One of these new potential building blocks is ferulic acid (FA) that is an aromatic cinnamic acid. FA has previously been used as an antioxidant but since it in addition is aromatic, have more than two functional groups and contains a double bond between two carbons it holds a large potential for polymeric synthesis. FA has been isolated from agricultural side streams such as sugar beet pulp, flax shives, wheat- and corn bran through enzymatic release and pressurised low-polarity water extraction (PLPW). One of the largest areas of use regarding FA is the biological applications. It has been proven to be effective protection against UV-radiation which open up possible uses in the textile industry, cosmetics and skincare. FA has also shown biomedical properties such as antiallergic, anti-inflammatory, anti-diabetic, anticarcinogenic and antiviral properties among others. Two of the most common polymerization methods are free radical- and step-wise polymerization. FA shows great promise for the possibility to polymerize through both these methods since it has a double bond and more than two functional groups. Polymer materials produced from FA has been done with step-wise polymerization. The polymers showed thermostable and possibly biodegradable properties. Free-radical polymerization requires a monomer with a sterically unhindered double bond and for that reason the FA must be modified in order to polymerize using free radicals. This modified monomer has been produced in a small laboratory scale and can in theory be polymerized through radical polymerization.Ett av de största problemen som vi står inför i modern tid är hur vi ska ersätta material som är producerade från fossila bränslen. Dessa material finns överallt i vårt moderna samhälle och spelar en betydelserik roll i vår infrastruktur. Detta har tvingat oss att undersöka andra miljövänligare källor för att se om dessa kan ersätta de fossila. Polymera material är ett exempel på material som tidigare har haft en fossil bas. På grund av detta har dessa material och hur dem kan producerats undersökt för att se om det finns en alternativ biobaserad källa. Ferulsyra är en aromatisk kanelsyra som är mest känd för att ha antioxidatiova egenskaper. Utöver detta innehåller ferulsyra en dubbelbindning mellan två kol och dessutom fler än två funktionella grupper vilket indikerar att den kan vara en möjlig monomer för polymersyntes. Ferulsyra kan produceras från sidoströmmar från jordbruksindustrin så som till exemper sockerbetsmassa, linhår och vete, både genom enzymatiska reaktioner eller med hjälp av extraktion med ett lösningsmedel. En av de största användningsområdena gällande ferulsyra är inom biologiska applikationer. Den kan bland annat användas som solskydd, både inom hudvårdsindustrin och som ytbeläggning i textilier. Ferulsyra har också uppvisat medicinska egenskaper som visar på att det kan användas mot allergier, inflammationer, diabetes, canser och virussjukdomar. De två vanligaste metoderna för polymersyntes är fri radikalpolymerisation och stegvis polymerisation. Ferulsyra uppvisar stor potential för att kunna användas som monomer i båda metoderna då den innehåller en dubbelbindning mellan två kol och fler än två funktionella grupper. Syntes av ferulsyra genom stegvis polymerisation har genomförts. Resultatet var att de producerade materialen uppvisade termostabila och biologiskt nedbrytbara egenskaper. För att fri radikalpolymerisation ska vara möjligt med ferulsyra som monomer krävs det att dubbelbindningen inte är steriskt hindrad. Detta innebär att ferulsyra först måste modifieras innan polymerisationen är möjlig. Dessa modifieringar har genomförts på labbskala och den producerade monomeren är teoretiskt sätt möjlig att polymerisera genom fri radikalpolymerisation.
17
Jureidini, Joelle. "Design, characterization and optimization of an atmospheric pressure hybrid dielectric barrier discharge reactor and application on a pharmaceutical compound." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99771.
Full textAbstract:
The main objectives of this project were to design, characterize and optimize a gas-liquid atmospheric pressure dielectric barrier discharge (DBD) reactor and to investigate its potential to degrade an aqueous pharmaceutical compound. The liquid was sandwiched inside a parallel plate semi-batch DBD reactor and thus, directly exposed to the plasma-forming region. The application of 10 kV (17.5 kHz) at low peak current (55 mA) between the high-voltage electrode, resting on an alumina plate, and the solution induced microdischarges in the gas phase and agitated the solution. The dissipated power (55 W on average) was monitored from the measure of Lissajous figures on a customized LabVIEW(TM) interface. Atomic oxygen was detected by optical emission spectroscopy when oxygen was used as the feed gas. An optimization of the operating conditions was performed by monitoring the absorbance at 600 nm (UV-visible) of blue solutions composed of an indigo dye. The effects of solution volume (42-55 mL) or discharge gap, gas flow rate (15-70 cc/min), treatment time (3-9 minutes), and gas type (pure oxygen or air) were investigated. Some of the optimum values for the operating parameters, which led to a discoloration efficiency of the indigo solution of 99%, were used to degrade an antibiotic, sulfamethoxazole (SMX) diluted in water.
18
Peyton, Daniel Junior. "Nitrogen-compound removal by ion exchange a model system study of the effect of nitrogen-compound type on the removal performance of two sulfonated styrene/divinylbenzene ion-exchange resins." Ohio : Ohio University, 1990. http://www.ohiolink.edu/etd/view.cgi?ohiou1183467365.
Full text
19
El, Masri Manal. "Synthesis of a Platinum Triamine Complex and its Interactions with Guanosine 5’- Monophosphate and N-Acetylmethionine." TopSCHOLAR®, 2018. https://digitalcommons.wku.edu/theses/3081.
Full textAbstract:
Cisplatin (cis-diamminedichloroplatinum(II)) and its analogs are known to form 1,2-intrastrand cross-links with guanine bases that lead to DNA distortion and are responsible for cytotoxicity. Reaction with proteins, especially at methionine residues, could also be responsible for cytotoxicity (Sandlin, R. D. et al. 2010). A new tridentate platinum(II) complex with a piperazine ring was successfully designed and synthesized. In this complex, the platinum is coordinating to all three nitrogens of (1,2- dimethylaminoethylpiperazine), which makes it a Platinum triamine compound. A series of chemical reactions of this compound with guanosine 5’-monophosphate (5’-GMP) and N-acetylmethionine (N-AcMet) were conducted under different conditions. Reactions with 5’-GMP show spectra suggesting that the triamine ligand is partially displaced as a second 5’-GMP residue coordinates. We are hoping that this newly synthesized compound may have anticancer properties, due the bulky structure of its nitrogen ligand.
20
Beck, Jeremy M. "Organophosphorus nerve agent chemistry; interactions of chemical warfare agents and their therapeutics with acetylcholinesterase." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313416337.
Full text
21
Abubakar, Mohamed Rania. "Tracing a compound with ecological importance for Ficus species and profiling the chemical constituents of Ficus obtusifolia." Thesis, Uppsala universitet, Avdelningen för farmakognosi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-434985.
Full text
22
Zhao, Yang. "Computational Methods for Analyzing Chemical Graphs and Biological Networks." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188864.
Full text
23
Tas, Baki Tugrul. "An Experimental Investigation Of The Shale Inhibition Properties Of A Quaternary Amine Compound." Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615554/index.pdf.
Full textAbstract:
Depleting oil reserves and increased costs of the oil and gas recoveries have created the need to drill
in challenging formations. When drilled through, shale formations in particular always generated a
wide variety of problems if conventional water-based muds are used. Furthermore, the complexity and
variations in shales have compounded the task of developing suitable drilling fluids. In light of these
problems, the study of shale properties and their interactions with fluids will continue to be a muchneeded
source of information in drilling industry.
In this study a low molecular weight quaternary amine compound, which is provided by KarKim
Drilling Fluids Inc., and its mixtures with sodium and potassium chloride is investigated in the aspects
of capillary suction times, hot rolling recoveries, methylene blue capacities and one-dimensional free
swelling properties in order to compare performances of salts and amine compound.
For all test methods quaternary amine concentration from 1% to 6% by volume were studied and seen
that less amount of quaternary amine compound is needed in order to obtain close shale recoveries
and shale volume change potential if compared with sodium and potassium chloride. This prevents the
usage of high concentration of chlorides and hence provides environmental sensitiveness.
Furthermore, it was concluded that combining an amount of salt with quaternary amine compound
gives the system enhanced shale inhibition properties.
24
Holmes, Adrian Lawrence. "Compound semiconductor native oxide-based technologies for optical and electrical devices grown on GaAs substrates using MOCVD /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
Full text
25
Lambert, Damien Jean Henri. "Growth and characterization of group III-nitride power transistors, power rectifiers and solar-blind detectors by metalorganic chemical vapor deposition /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004311.
Full text
26
Bradshaw, James Adam Ferguson. "Novel studies on the formation and chemical reactivity of compound clusters and their precursors in the gas and liquid phase." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26512.
Full textAbstract:
Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009.Committee Chair: Whetten, Robert; Committee Member: Bottomley, Lawrence; Committee Member: de Heer, Walter; Committee Member: El-Sayed, Mostafa; Committee Member: Fernandez, Facundo; Committee Member: Gordon, Sidney; Committee Member: Leavitt, Andrew; Committee Member: Orlando, Thomas. Part of the SMARTech Electronic Thesis and Dissertation Collection.
27
Miya, Senzo Simo. "Atmospheric pressure metal-organic vapour phase epitaxial growth of InAs/GaSb strained layer superlattices." Thesis, Nelson Mandela Metropolitan University, 2013. http://hdl.handle.net/10948/d1020866.
Full textAbstract:
The importance of infrared (IR) technology (for detection in the 3-5 μm and 8-14 μm atmospheric windows) has spread from military applications to civilian applications since World War II. The commercial IR detector market in these wavelength ranges is dominated by mercury cadmium telluride (MCT) alloys. The use of these alloys has, however, been faced with technological difficulties. One of the materials that have been tipped to be suitable to replace MCT is InAs/InxGa1-xSb strained layer superlattices (SLS’s). Atmospheric pressure metal-organic vapour phase epitaxy (MOVPE) has been used to grow InAs/GaSb strained layer superlattices (SLS’s) at 510 °C in this study. This is a starting point towards the development of MOVPE InAs/InxGa1-xSb SLS’s using the same system. Before the SLS’s could be attempted, the growth parameters for GaSb were optimised. Growth parameters for InAs were taken from reports on previous studies conducted using the same reactor. Initially, trimethylgallium, a source that has been used extensively in the same growth system for the growth of GaSb and InxGa1-xSb was intended to be used for gallium species. The high growth rates yielded by this source were too large for the growth of SLS structures, however. Thus, triethylgallium (rarely used for atmospheric pressure MOVPE) was utilized. GaSb layers (between 1 and 2 μm thick) were grown at two different temperatures (550 °C and 510 °C) with a varying V/III ratio. A V/III ratio of 1.5 was found to be optimal at 550 °C. However, the low incorporation efficiency of indium into GaSb at this temperature was inadequate to obtain InxGa1-xSb with an indium mole fraction (x) of around 0.3, which had previously been reported to be optimal for the performance of InAs/InxGa1-xSb SLS’s, due to the maximum splitting of the valence mini bands for this composition. The growth temperature was thus lowered to 510 °C. This resulted in an increase in the optimum V/III ratio to 1.75 for GaSb and yielded much higher incorporation efficiencies of indium in InxGa1-xSb. However, this lower growth temperature also produced poorer surface morphologies for both the binary and ternary layers, due to the reduced surface diffusion of the adsorbed species. An interface control study during the growth of InAs/GaSb SLS’s was subsequently conducted, by investigating the influence of different gas switching sequences on the interface type and quality. It was noted that the growth of SLS’s without any growth interruptions at the interfaces leads to tensile strained SLS’s (GaAs-like interfaces) with a rather large lattice mismatch. A 5 second flow of TMSb over the InAs surface and a flow of H2 over GaSb surface yielded compressively strained SLS’s. Flowing TMIn for 1 second and following by a flow of TMSb for 4 seconds over the GaSb surface, while flowing H2 for 5 seconds over the InAs surface, resulted in SLS’s with GaAs-like interfacial layers and a reduced lattice mismatch. Temperature gradients across the surface of the susceptor led to SLS’s with different structural quality. High resolution x-ray diffraction (HRXRD) was used to determine the thicknesses as well as the type of interfacial layers. The physical parameters of the SLS’s obtained from simulating the HRXRD spectra were comparable to the parameters obtained from cross sectional transmission electron microscopy (XTEM) images. The thicknesses of the layers and the interface type played a major role in determining the cut-off wavelength of the SLS’s.
28
Alquist, Keith Eldred III. "Structural studies of phase behavior in 1,6-dicyanohexane/urea and 1,6-diisocyanohexane/urea inclusion compounds." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18814.
Full textAbstract:
Master of ScienceDepartment of Chemistry
Mark Hollingsworth
The crystal structures of the inclusion compounds 1,6-diisocyanohexane/urea and 1,6-dicyanohexane/urea were refined at several temperatures from X-ray data. These urea inclusion compounds are commensurate structures with host:guest ratios of 6:1. In contrast with the ordinary helical topology of the urea host, these structures have stacked loop topologies of the host hydrogen bonds and crystallize in space group P21/n. At room temperature, both structures are distorted along [001] from hexagonal metric symmetry. As in earlier studies of 1-chloro-6-cyanohexane/urea, cooling 1,6-diisocyanohexane/urea gives rise to an exothermic phase transition (Hº = -856 cal mol 1, Sº = -5 cal mol-1 K-1) at 175 K that results in the cooperative translation of guest molecules by 5.5 Å along the channel axis. In the low temperature form, 1,6-diisocyanohexane/urea is distorted along [100], much like X(CH2)6Y, where X, Y = Br, Cl. Although the crystal structure of 1,6-dicyanohexane/urea is essentially isomorphous with that of the high temperature form of 1,6-diisocyanohexane/urea, it does not undergo an equivalent phase transition at low temperatures. Both of these systems exhibit dynamic disorder between two gauche conformers of the guest, which have mean planes of the alkyl chains lying within 1º of [100] (major conformer) and approximately 14º from [001] (minor conformer). The temperature dependence of site occupancy factors for the disordered sites yielded enthalpy differences between major and minor sites in 1,6-diisocyanohexane/urea and 1,6-dicyanohexane/urea of 216 and 127 cal mol 1, respectively. Since the low temperature form of 1,6-diisocyanohexane/urea is distorted along [100], this is favored at low temperatures by an increased concentration of the major conformer, which predominates in 1,6-dibromohexane/urea and congeners. In 1,6-diisocyanohexane/urea, the phase transition to the low temperature form occurs at a threshold concentration for the major conformer of 67%. With its shallower temperature dependence, 1,6-dicyanohexane/urea should not reach this threshold population until approximately 92 K, at which temperature the system cannot overcome the barrier for cooperative translation of guests along the channel axis.
29
Morin, Nicolas. "Évaluation du POCIS (Polar Organic Chemical Integrative Sampler) : domaine de validité et performances pour 56 micropolluants organiques : application aux hormones, pharmaceutiques, alkyphénols, filtre UV et pesticides." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10056.
Full textAbstract:
Le POCIS (Polar Organic Chemical Integrative Sampler) est un outil d'échantillonnage intégratif alternatif aux techniques d'échantillonnages classiques (ponctuelle ou automatisée) dédié à la mesure de micropolluants organiques relativement hydrophiles dans les eaux. Cet outil permet d'intégrer les concentrations dans le temps (CTWA, Time-Weighted Average Concentration) et, dans certains cas, d'abaisser les limites de quantification. Une revue bibliographique détaillée a montré la forte variabilité des données de performances du POCIS mesurées en laboratoire (notamment les taux d'échantillonnage ou Rs). Cette variabilité résulte en majeure partie de systèmes expérimentaux d'étalonnage différents selon les études et pas toujours renseignés. Dans la littérature, les CTWA obtenues in situ sont comparées aux concentrations obtenues après échantillonnage classique, tel que mis en œuvre actuellement dans les programmes de surveillance européens ; ces concentrations sont dans la plupart des cas du même ordre de grandeur, même si elles ne représentent pas tout à fait la même information. Avec comme objectif d'obtenir des CTWA les plus justes et robustes possibles, nous avons étudié le comportement du POCIS « pharmaceutique » en laboratoire vis-à-vis de 56 micropolluants (hormones, pharmaceutiques, alkylphénols, pesticides, filtre UV), dans un système expérimental d'étalonnage conçu spécifiquement pour contrôler l'ensemble des conditions expérimentales ayant une influence sur les Rs. Nous avons ainsi déterminé 43 Rs robustes et démontré que le POCIS est bien adapté à l'échantillonnage de la plupart des molécules étudiées. De plus, l'allure des cinétiques d'accumulation est expliquée à l'aide des propriétés physico-chimiques des molécules (log D , surface polaire). Cinq homologues deutérés ont été identifiés en tant que PRC (Performance Reference Compounds), c'est-à-dire qu'ils peuvent être utilisés pour corriger les différences de conditions entre le laboratoire et le terrain. Nous avons également comparé le POCIS au Chemcatcher « polaire » en laboratoire et montré qu'en terme de domaine d'application et de performances, le POCIS est mieux adapté pour les micropolluants étudiés. Enfin, nous avons testé la justesse et la robustesse du POCIS lors de deux essais inter-laboratoires (EIL). Le premier EIL, portant sur l'étalonnage de l'outil en laboratoire, a démontré la robustesse de ses performances pour 3 pesticides. Le deuxième EIL in situ a démontré la pertinence du POCIS pour échantillonner des hormones, des pharmaceutiques et des pesticides dans un effluent de station d'épuration. Cette thèse permet d'avancer dans le domaine des connaissances sur l'outil POCIS et de favoriser son application dans le cadre de la directive sur l'eauThe POCIS (Polar Organic Chemical Integrative Sampler) is an alternative integrative sampling tool to conventional sampling methods (grab or automated) for measuring hydrophilic organic micropollutants in water. This tool permits to supply time-weighted average concentrations (TWAC) and, sometimes, to decrease limits of quantification. A detailed bibliographic review showed the important variability of POCIS performance data measured in laboratory (notably the sampling rates or Rs). This variability is in majority due to different experimental calibration systems, not always well detailed, among studies. In the literature, in situ TWAC are compared to concentrations from conventional sampling, actually used in European monitoring programs ; these concentrations are generally of the same order of magnitude, even if they do not represent the same information. In order to obtain accurate and robust TWAC, we studied in laboratory the “pharmaceutical” POCIS behavior for 56 micropollutants (hormones, pharmaceuticals, alkylphenols, pesticides, UV filter), in a calibration system specifically made for controlling the whole experimental conditions having an influence on Rs. We determined 43 robust RS and demonstrated that POCIS is well adapted for sampling most of studied molecules. Moreover, the pattern of kinetic accumulations is explained using molecule physical-chemical properties (log D, polar surface). Five deuterated homologues were identified as PRCs, meaning that they can be used for correcting differences in conditions between the laboratory and the field. We also compared the POCIS with the “polar” Chemcatcher and we showed that in term of application field and performances, the POCIS is better adapted for studied micropollutants. At last, we tested the accuracy and the robustness of the POCIS during two inter-laboratory studies (ILSs). The first ILS, dealing with the laboratory calibration of the tool, demonstrated performance robustness for 3 pesticides. The second in situ ILS demonstrated the relevance of the POCIS for sampling hormones, pharmaceuticals and pesticides from a waste water treatment plant effluent. This thesis permits to improve knowledge on the POCIS and to promote its application for the water framework directive
30
Kwiatkowski, Angela. "Características agronômicas, qualidade e composição química dos grãos de híbridos simples de milho doce." Universidade Estadual de Maringá, 2007. http://repositorio.utfpr.edu.br/jspui/handle/1/167.
Full textAbstract:
CNPQO milho doce (Zea mays L.) possui ampla versatilidade, além de agregar valor ao produto. Este tipo de milho vem sendo consumido em diversos países na forma de espiga cozida “in natura”, congelada ou como grãos enlatados. No Brasil, várias agroindústrias fomentam a produção e comercialização do milho doce enlatado em conserva. Dessa forma, seu cultivo vem crescendo gradativamente, atraindo a atenção dos produtores de milho verde. O presente trabalho possui como objetivos: avaliar caracteres agronômicos, a qualidade e a composição química dos grãos de híbridos simples de milho doce apropriados para consumo "in natura" e, também, pela indústria de milho verde em conserva. As sete linhagens foram selecionadas e fornecidas para o cruzamento dialélico pelo Programa de Melhoramento Genético da Universidade Estadual de Maringá, sendo obtidos os 21 híbridos simples. O delineamento experimental foi o de blocos completos casualizados com quatro repetições. As características avaliadas no campo foram: altura de plantas, altura de inserção das espigas e massa das espigas sem palha (kg ha-1). As avaliações químicas realizadas foram: determinação de açúcares redutores e totais, amido, proteínas, extrato etéreo, fibras e cinzas. Para as análises estatísticas, foi utilizada a análise de variância e na comparação das médias foi utilizado o teste de agrupamento Scott- Knott (1974) com probabilidade mínima de 5%. Para a análise de combinação entre as linhagens genitoras e os híbridos simples obtidos (capacidade geral de combinação – CGC - e capacidade específica de combinação - CEC) foi utilizado o método 4 de Griffing e o modelo fixo (1956). Os resultados médios obtidos indicam que, para a avaliação da altura de plantas e espigas, não houve diferença significativa x (P>0,05), e para a composição química, houve diferença significativa (P<0,05) pelo teste de agrupamento de médias de Scott-Knott (1974) entre os híbridos avaliados. Na análise combinatória, as linhagens de milho doce que se destacaram para os cruzamentos realizados foram as linhagens L4 e L5. Os híbridos L4xL5 e L3xL7 são os mais indicados para produção, quando se objetiva a maior concentração de açúcares e menor teor de amido na composição.
Sweet corn (Zea mays L.) possesses wide versatility, besides adding value to the product. This corn type has been consumed ‘in natura’ in several countries, in form of cooked ears, or in frozen or canned grains. In Brazil, several agribusinesses foment the production and commercialization of canned sweet corn. Thus, its cultivation has been growing gradually, attracting the attention of green corn producers. The present paper has as objective to evaluate the agronomic characters, the quality and the chemical composition of the grains of sweet corn, simple hybrids, appropriate for consumption ‘in natura’, and the corn to be used in the green corn industry. Seven lineages were selected and supplied for the dialectic crossing by the Program of Genetics Improvement of the State University of Maringá, thus obtaining 21 simple hybrids. The experimental outlining occurred by using complete randomized blocks with four replications. The characteristics appraised in the cultivars were: height of plants, height of ear insertion and mass of corn ears, without straw (kg ha-1). The chemical evaluations carried out were the ones regarding: determination of reducer and total sugars, starch, proteins, ethereal extract, fibers and ashes. Variance analysis was used for the statistical analyses, whereas Scott-Knott cluster test (1974) was used in the comparison of averages, with a minimum probability of 5%. For the combining analysis, between the genitor lineages and the simple hybrids obtained (usual combination capacity - UCC - and specific combination capacity - SCC), both, method 4 and the fixed model by Griffing (1956) were used. The average results obtained showed that there was no significant difference when the evaluating the height of plants and corns ears (P>0.05), but on xii the other hand, of chemical composition showed significant difference (P<0.05) in the test regarding average clustering, by Scott-Knott (1974) for the hybrids appraised. But L4 and L5 sweet corn lineages were the ones highlighted for the crossings accomplished in the combining analysis. Both, L4xL5 and L3xL7 hybrids were the most suitable for production, when aiming at obtaining the largest concentration of sugars, together with the smallest content of starch, in its compound.
31
Brown, Jason David. "Development of an Effective Therapeutic for Nerve Agent Inhibited and Aged Acetylcholinesterase." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1334341199.
Full text
32
Völker, Doris. "Chemical-sensitive genes in zebrafish (Danio rerio) early development - identification and characterisation of differential expression in embryos exposed to the model compound 3,4-dichloroaniline." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1175770841778-45567.
Full textAbstract:
In the European Union an environmental risk assessment is required for the registration of new chemicals, biocides, pesticides and pharmaceuticals. In order to avoid the release of potential hazardous substances, various ecotoxicity tests are performed, including acute and chronic fish tests. As a consequence of the new program of the European Union “Registration, Evaluation and Authorisation of Chemicals” (REACH) the number of animal experiments for environmental risk assessment is expected to increase remarkably within the next years. On the other hand there is a strong societal demand for reducing the number of animal tests by using alternative in vitro models. According to EU directives, investigations using non-human vertebrate embryos are considered pain free in vitro methods and are therefore accepted as alternatives to animal experiments. For the acute fish test, the Danio rerio embryo test (DarT) has been established as a replacement method and included in national regulations at least for waste water (German Waste Water Dues Law). However, no alternatives for chronic fish tests are currently available. The overall goal of this thesis was to work towards such a replacement by extending DarT zu Gene-DarT. Toxicants will initially interact at the molecular level with consequences for physiology, fitness and survival. The analysis of gene expression patterns may unravel elements of these molecular events before any phenotypic changes are visible. The hypothesis of this thesis therefore was that chemical-sensitive genes in embryos exposed in a conventional DarT may indicate toxic impact of substances at sub-acute concentrations and thus enhance the sensitivity of the embryo toxicity test. Furthermore, unlike the conventional DarT-endpoints, gene expression analysis will provide insights into mechanistic processes underlying toxicity. The 3,4-dichloroaniline (3,4-DCA), which is used as a reference compound in the DarT, was selected as model chemical in this thesis. In a first step, differentially expressed genes in embryos exposed to 3,4-DCA were identified by microarray technology and RT-PCR techniques. Six dose-dependent significant differentially expressed genes were identified. These genes were involved in biotransformation pathways (cyp1a, ahr2), stress response (nrf2, maft, ho-1) and cell cycle control (fzr1). Differential expression upon 3,4-DCA exposure was detected below the LOEC (lowest observed effect concentration = 6.2 µM) of survival or developmental disorders of the embryo test (0.78 µM and above). For the validation of stage specific sensitivity, genes were also analysed in post-hatched stages. Extension of exposure to post-hatched stages resulted in a differential expression at lower concentrations as for the embryonic stages, indicating an improved sensitivity due to stage-specific sensitivity or exposure time. To confirm the adaptive function of the 3,4-DCA-sensitive genes, embryonic mRNA abundance was experimentally manipulated by knock down and overexpression. By injection of sense (mRNA) or antisense (siRNA) RNA in one-cell-stages of embryos, the transcript levels of genes were transiently enhanced or repressed in embryos exposed to 3,4-DCA. mRNA injection of the genes cyp1a, ho-1 and nrf2 reduced the number of embryos with 3,4-DCA-induced malformations. In contrast, siRNA injections for the same genes led to an increase in the severity and frequency of developmental disorders. The results clearly indicate the adaptive functions of the investigated genes or their corresponding proteins. This study demonstrates that the analysis of chemical-sensitive gene expression shows the potential to increase the sensitivity of conventional toxicity tests. The analysis of gene expression also provides additional mechanistic information for toxic action, e.g. in the presented study, the involvement of Ah-receptor regulated pathways as an adaptive response. Furthermore, the presented data indicate that functional manipulations, using mRNA and siRNA-injection, are suitable to evaluate the role of differentially expressed genes for toxicity.
33
Völker, Doris Maria. "Chemical-sensitive genes in zebrafish (Danio rerio) early development - identification and characterisation of differential expression in embryos exposed to the model compound 3,4-dichloroaniline." Leipzig : Helmholtz-Zentrum für Umweltforschung GmbH - UFZ, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1175770841778-45567.
Full text
34
Völker, Doris. "Chemical-sensitive genes in zebrafish (Danio rerio) early development - identification and characterisation of differential expression in embryos exposed to the model compound 3,4-dichloroaniline." Doctoral thesis, Technische Universität Dresden, 2006. https://tud.qucosa.de/id/qucosa%3A24932.
Full textAbstract:
In the European Union an environmental risk assessment is required for the registration of new chemicals, biocides, pesticides and pharmaceuticals. In order to avoid the release of potential hazardous substances, various ecotoxicity tests are performed, including acute and chronic fish tests. As a consequence of the new program of the European Union “Registration, Evaluation and Authorisation of Chemicals” (REACH) the number of animal experiments for environmental risk assessment is expected to increase remarkably within the next years. On the other hand there is a strong societal demand for reducing the number of animal tests by using alternative in vitro models. According to EU directives, investigations using non-human vertebrate embryos are considered pain free in vitro methods and are therefore accepted as alternatives to animal experiments. For the acute fish test, the Danio rerio embryo test (DarT) has been established as a replacement method and included in national regulations at least for waste water (German Waste Water Dues Law). However, no alternatives for chronic fish tests are currently available. The overall goal of this thesis was to work towards such a replacement by extending DarT zu Gene-DarT. Toxicants will initially interact at the molecular level with consequences for physiology, fitness and survival. The analysis of gene expression patterns may unravel elements of these molecular events before any phenotypic changes are visible. The hypothesis of this thesis therefore was that chemical-sensitive genes in embryos exposed in a conventional DarT may indicate toxic impact of substances at sub-acute concentrations and thus enhance the sensitivity of the embryo toxicity test. Furthermore, unlike the conventional DarT-endpoints, gene expression analysis will provide insights into mechanistic processes underlying toxicity. The 3,4-dichloroaniline (3,4-DCA), which is used as a reference compound in the DarT, was selected as model chemical in this thesis. In a first step, differentially expressed genes in embryos exposed to 3,4-DCA were identified by microarray technology and RT-PCR techniques. Six dose-dependent significant differentially expressed genes were identified. These genes were involved in biotransformation pathways (cyp1a, ahr2), stress response (nrf2, maft, ho-1) and cell cycle control (fzr1). Differential expression upon 3,4-DCA exposure was detected below the LOEC (lowest observed effect concentration = 6.2 µM) of survival or developmental disorders of the embryo test (0.78 µM and above). For the validation of stage specific sensitivity, genes were also analysed in post-hatched stages. Extension of exposure to post-hatched stages resulted in a differential expression at lower concentrations as for the embryonic stages, indicating an improved sensitivity due to stage-specific sensitivity or exposure time. To confirm the adaptive function of the 3,4-DCA-sensitive genes, embryonic mRNA abundance was experimentally manipulated by knock down and overexpression. By injection of sense (mRNA) or antisense (siRNA) RNA in one-cell-stages of embryos, the transcript levels of genes were transiently enhanced or repressed in embryos exposed to 3,4-DCA. mRNA injection of the genes cyp1a, ho-1 and nrf2 reduced the number of embryos with 3,4-DCA-induced malformations. In contrast, siRNA injections for the same genes led to an increase in the severity and frequency of developmental disorders. The results clearly indicate the adaptive functions of the investigated genes or their corresponding proteins. This study demonstrates that the analysis of chemical-sensitive gene expression shows the potential to increase the sensitivity of conventional toxicity tests. The analysis of gene expression also provides additional mechanistic information for toxic action, e.g. in the presented study, the involvement of Ah-receptor regulated pathways as an adaptive response. Furthermore, the presented data indicate that functional manipulations, using mRNA and siRNA-injection, are suitable to evaluate the role of differentially expressed genes for toxicity.
35
Legoupy, Stéphanie. "Synthèse et réactivité de nouveaux complexes organométalliques chiraux du rhénium." Rennes 1, 1997. http://www.theses.fr/1997REN10148.
Full textAbstract:
Le travail présenté dans ce mémoire concerne la synthèse et la réactivité de complexes du rhénium. De nouveaux complexes organométalliques chiraux du rhénium des alcools propargyliques et homoallylique ont été synthétisés. Des alcools allyliques secondaires et 1,2-disubstitues ont été coordonnés à l'entité chirale (#5C#5H#5)Re(No)(Pph#3)#+Bf#4#-. Dans le cas du 3-buten-2-ol complexe, les deux diastéréoisomères ont pu été séparés. L'étude de la réactivité de ces complexes du rhénium a montré qu'ils sont compatibles avec des réactions d'oxydation, de Wittig, de réduction, d'estérification, de chloration, de bromation et de fluoration. L'entité organométallique (#5C#5H#5)Re(No)(Pph#3)#+Bf#4#- s'est montrée un bon groupement protecteur d'une seule double liaison au cours de ces réactions. Les substitutions allyliques, catalysées par un acide de Lewis, sur les complexes du rhénium des alcools allyiques ont été étudiées. Quelque soit le nucléophile, ces réactions sont régio- et stéréosélectives et se font avec rétention de configuration. Un mécanisme impliquant un complexe -allyl dicationique du rhénium a été proposé. Le rôle activateur du rhénium a été mis en évidence.
36
Lu, Yingying, and 卢盈颖. "Mechanistic study on the inhibition of the late stage of basal autophagy progression by a natural compound (NAADP) and a synthetic small chemical (vacuolin-1)." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/207179.
Full textAbstract:
Autophagy is a catabolic lysosomal degradation process essential for cellular homeostasis and cell survival. Dysfunctional autophagy has been associated with wide ranges of human diseases, e.g. cancer and neurodegenerative diseases. Although enormous progress has been made on the core molecular machineries of autophagy, mechanisms of autophagy induction, autophagosome maturation, and autophagosomal-lysosomal fusion still remain elusive in mammalian cells.
The two pore channel 2 (TPC2) is a new member of the superfamily of voltage-gated Na+/Ca2+ channels located on lysosomes. Accumulating evidence indicates that nicotinic acid adenine dinucleotide phosphate (NAADP), one of the most potent Ca2+ mobilizing nucleotides, elicits Ca2+ release from lysosomes via TPC2 in many cell types. Herein, we first studied the role and mechanism of NAADP/TPC2/Ca2+ signaling in regulation of autophagy in mammalian cells. We found that overexpression TPC2 in Hela cells or mouse embryonic stem (ES) cells inhibited autophagosomal-lysosomal fusion, thereby resulting in the accumulation of autophagosomes. Treatment of TPC2 expressing cells with NAADP-AM, a cell-permeant NAADP agonist, further induced the accumulation, whereas Ned-19, a NAADP antagonist, reversed it. Interestingly, inhibiting MTOR activity failed to increase TPC2-induced autophagosome accumulation, but ATG5 knockdown markedly blocked it. Importantly, overexpression of TPC2 alkalinized lysosomal pH, whereas lysosomal re-acidification abolished TPC2-induced autophagosome accumulation. In addition, TPC2 overexpression had no effect on general endosomal-lysosomal degradation but prevented the recruitment of Rab-7 to autophagosomes. Taken together, our data demonstrate that NAADP/TPC2/Ca2+ signaling alkalinizes lysosomal pH to specifically inhibit the later stage of basal autophagy progression. Development of agonists or antagonists of NAADP should provide a novel approach to specifically manipulate autophagy.
Along this line, a large number of small chemicals that modulate autophagy have actually been widely used to dissect this process and some of them, e.g. chloroquine (CQ), might be ultimately applied to treat a variety of autophagy-associated human diseases. Yet most of the autophagy chemical modulators lack specificity, or potency, or both. Therefore we screened a panel of small chemicals that are commercially available and have been previously shown to affect vesicle trafficking or organelle morphology on autophagy regulation. We found that vacuolin-1, a cell permeable small molecule, potently and reversibly inhibited autophagosomal-lysosomal fusion in mammalian cells, thereby inducing the accumulation of autophagosomes. Vacuolin-1 treatment also blocked the fusion between endosomes and lysosomes, resulting in a defect in general endosomal-lysosomal degradation. Interestingly, treatment of cells with vacuolin-1 alkalinized lysosomal pH and decreased lysosomal Ca2+ content. Besides marginally inhibiting vacuolar ATPase activity, vacuolin-1 treatment markedly activated Rab5 GTPase activity. Expression of a dominant negative mutant of Rab5A or Rab5A knockdown significantly inhibited vacuolin-1 induced autophagosomal-lysosomal fusion blockage, whereas expression of a constitutive active form of Rab5A suppressed the lysosomal-autophagosomal fusion. Taken together, these data suggest that vacuolin-1 activates Rab5A to suppress the autophagosomal-lysosomal fusion, possibly via alkalizing lysosomal pH. Moreover, vacuolin-1 treatment alone showed little cell toxicity, but markedly suppressed the colony formation and migration of tumor cells in vitro. Therefore, vacuolin-1 and its analogues present a novel class of drug that can potently and reversibly modulate autophagy, and are potential drugs for treating autophagy related human diseases, e.g. cancer.published_or_final_version
Physiology
Doctoral
Doctor of Philosophy
37
Katsube, Ryoji. "Investigation on properties of zinc phosphide related materials and interfaces for optoelectronic devices." Kyoto University, 2018. http://hdl.handle.net/2433/232037.
Full text
38
Hoffman, Timothy B. "Optimization and characterization of bulk hexagonal boron nitride single crystals grown by the nickel-chromium flux method." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32797.
Full textAbstract:
Doctor of PhilosophyDepartment of Chemical Engineering
James H. Edgar
Hexagonal boron nitride (hBN) is a wide bandgap III-V semiconductor that has seen new interest due to the development of other III-V LED devices and the advent of graphene and other 2-D materials. For device applications, high quality, low defect density materials are needed. Several applications for hBN crystals are being investigated, including as a neutron detector and interference-less infrared-absorbing material. Isotopically enriched crystals were utilized for enhanced propagation of phonon modes. These applications exploit the unique physical, electronic and nanophotonics applications for bulk hBN crystals. In this study, bulk hBN crystals were grown by the flux method using a molten Ni-Cr solvent at high temperatures (1500°C) and atmospheric pressures. The effects of growth parameters, source materials, and gas environment on the crystals size, morphology and purity were established and controlled, and the reliability of the process was greatly improved. Single-crystal domains exceeding 1mm in width and 200μm in thickness were produced and transferred to handle substrates for analysis. Grain size dependence with respect to dwell temperature, cooling rate and cooling temperature were analyzed and modeled using response surface morphology. Most significantly, crystal grain width was predicted to increase linearly with dwell temperature, with single-crystal domains exceeding 2mm in at 1700°C. Isotopically enriched ¹⁰B and ¹¹B hBN crystal were produced using a Ni-Cr-B flux method, and their properties investigated. ¹⁰B concentration was evaluated using SIMS and correlated to the shift in the Raman peak of the E[subscript 2g] mode. Crystals with enrichment of 99% ¹⁰B and >99% ¹¹B were achieved, with corresponding Raman shift peaks at 1392.0 cm⁻¹ and 1356.6 cm⁻¹, respectively. Peak FWHM also decreased as isotopic enrichment approached 100%, with widths as low as 3.5 cm⁻¹ achieved, compared to 8.0 cm⁻¹ for natural abundance samples. Defect selective etching was performed using a molten NaOH-KOH etchant at 425°C-525°C, to quantify the quality of the crystals. Three etch pit shapes were identified and etch pit width was investigated as a function of temperature. Etch pit density and etch pit activation energy was estimated at 5×10⁷ cm⁻² and 60 kJ/mol, respectively. Screw and mixed-type dislocations were identified using diffraction-contrast TEM imaging.
39
Noguchi, Taro. "Development of a Screening Process from Virtual Mirror-image Library of Natural Products Using D-Protein Technology." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225537.
Full text
40
Elhag, Sami. "Chemically Modified Metal Oxide Nanostructures Electrodes for Sensing and Energy Conversion." Doctoral thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-134275.
Full textAbstract:
The goal of this thesis is the development of scalable, low cost synthesis of metal oxide nanostructures based electrodes and to correlate the chemical modifications with their energy conversion performance. Methods in energy conversion in this thesis have focused on two aspects; a potentiometric chemical sensor was used to determine the analytical concentration of some components of the analyte solution such as dopamine, glucose and glutamate molecules. The second aspect is to fabricate a photo-electrochemical (PEC) cell. The biocompatibility, excellent electro-catalytic activities and fast electron transfer kinetics accompanied with a high surface area to volume ratio; are properties of some metal oxide nanostructures that of a potential for their use in energy conversion. Furthermore, metal oxide nanostructures based electrode can effectively be improved by the physical or a chemical modification of electrode surface. Among these metal oxide nanostructures are cobalt oxide (Co3O4), zinc oxide (ZnO), and bismuth-zincvanadate (BiZn2VO6) have all been studied in this thesis. Metal oxide nanostructures based electrodes are fabricated on gold-coated glass substrate by low temperature (< 100 0C) wet chemicalapproach. X-ray diffraction, x-ray photoelectron spectroscopy and scanning electron microscopy were used to characterize the electrodes while ultraviolet-visible absorption and photoluminescence were used to investigate the optical properties of the nanostructures. The resultant modified electrodes were tested for their performance as chemical sensors and for their efficiency in PEC activities. Efficient chemically modified electrodes were demonstrated through doping with organic additives like anionic, nonionic or cationic surfactants. The organic additives are showing a crucial role in the growth process of metal oxide nanocrystals and hence can beused to control the morphology. These organic additives act also as impurities that would significantly change the conductivity of the electrodes. However, no organic compounds dependence was observed to modify the crystallographic structure. The findings in this thesis indicate the importance of the use of controlled nanostructures morphology for developing efficient functional materials.
41
McNeilly, Ryan J. "Nanostructured Microcantilever for the Detection of Volatile Compounds." University of Dayton / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1511803746331593.
Full text
42
Arnaout, Abdulkarim al. "Synthese regioselective de dihydropyridines et de pyridines 2- ou 4-fonctionnalisees : applications." Poitiers, 1987. http://www.theses.fr/1987POIT2254.
Full text
43
Jin, Peng. "Mechanism of Corrosion by Naphthenic Acids and Organosulfur Compounds at High Temperatures." Ohio University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1384872234.
Full text
44
Hiouni, Abdelaziz. "Première synthèse des α-lithioacétals de cétène : condensation avec les dérivés carbonylés." Rouen, 1996. http://www.theses.fr/1996ROUES074.
Full textAbstract:
Pour la première fois des alpha-lithioacétals de cétène ont été obtenus. Ils ont été préparés par échange brome-lithium à partir de bromoacétals de cétène. La condensation de ces réactifs à fonction ester masquée conduit soit à des esters α, β-éthyléniques (hydrolyse acide), soit à des β-hydroxyesters (hydrolyse basique). De plus la protonation de l'intermédiaire de condensation lithié par le bromure de tertio-butyle conduit a des β-hydroxyacétals de cétène, non décrits dans la littérature. Dans certains cas la supériorité de ces lithioacétals de cétène par rapport aux réactifs classiques (Reformatsky, Wittig, Wittig-Horner-Emmons) a été montrée. Bien que possédant un groupement alcoxy en trans de l'atome de lithium les α-lithioacétals de cétène ne se transforment pas en alcoxyacétylènes par transélimination d'alcoolates de lithium contrairement aux 1-lithio-2-alcoxyéthylènes trans.
45
Feng, Liwen. "Chemical tools for antimalarial drug development : synthesis of plasmodione analogues and 13C-enriched plasmodione for drug metabolomics investigations." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF038.
Full textAbstract:
Le paludisme est une maladie parasitaire tropicale menaçant les populations dans les zones tropicales et sub-tropicales, en particulier les jeunes enfants en Afrique. En raison des résistances aux médicaments antipaludiques qui se sont propagées dans le monde entier au cours des 50 dernières années, de nouveaux médicaments sont vraiment nécessaires. La plasmodione (série benzylmenadione) a été identifiée comme un médicament-candidat antipaludique puissant, agissant selon une bioactivation rédox sur les stades sanguins asexués et sexués jeunes, mais son métabolisme est inconnu. Par conséquent, afin d'identifier les structures des métabolites actifs générés par la plasmodione antipaludique, la synthèse complète de la plasmodione 13C18-enrichie a été conçue et réalisée en 10 étapes. En outre, le procédé d'extraction pour l'étude du métabolisme de la molécule a été établi à partir de globules rouges parasités traités par la plasmodione 13C18-enrichie. D'autre part, la préparation de dérivés oxétane et N-alkylaryl de plasmodione avec une solubilité potentielle améliorée a également été réalisée par substitution nucléophilie aromatique (SNAr) et réaction de couplage Buchwald-Hartwig catalysée par le palladium, respectivement. Enfin, un complexe d'or (I) phosphole, connu comme un inhibiteur irréversible et puissant de la thiorédoxine réductase séléno-dépendante humaine, a été synthétisé et son profil antiparasitaire a été étudié sur de nombreux parasites pathogènes pour l’homme, protozoaires et helminthes en culturesMalaria is a tropical parasitic disease threatening populations in tropical and sub-tropical areas, especially young children in Africa. Due to the drug resistance spread all over the world in the past 50 years, new drugs are urgently needed. Plasmodione (benzylmenadione series) had been identified as a potent anti-malarial early lead drug, acting through a redox bioactivation on asexual and young sexual blood stages, but its drug metabolism is unknown. Therefore, in order to identify the structures of the active drug metabolites generated from the antimalarial plasmodione, fully 13C18-enriched-plasmodione synthesis was designed and performed in 10 steps. Furthermore, the extraction method for the drug metabolism study was established from 13C18-enriched plasmodione-treated parasitized red blood cells. On the other hand, the preparation of oxetane and N-alkylaryl derivatives of plasmodione with potential improved solubility was also investigated through aromatic nucleophilic substitution (SNAr) and palladium-catalyzed Buchwald-Hartwig coupling reaction, respectively. Finally, a gold(I) phosphole complex, known as an irreversible and potent inhibitor of the human seleno-dependent thioredoxin reductase, was synthetized and its antiparasitic profile investigated against a panel of parasites, protozoans and helminthes in cultures
46
MIRANDA, Márcio Fléquisson Alves. "Diagnóstico e recuperação de solos afetados por sais em perímetro irrigado do sertão de Pernambuco." Universidade Federal Rural de Pernambuco, 2013. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/5367.
Full textAbstract:
Submitted by (lucia.rodrigues@ufrpe.br) on 2016-08-17T12:15:41Z
No. of bitstreams: 1
Marcio Flequisson Alves Miranda.pdf: 1217281 bytes, checksum: bd45c2f7f20927f1da595dfd05965a6a (MD5)Made available in DSpace on 2016-08-17T12:15:42Z (GMT). No. of bitstreams: 1 Marcio Flequisson Alves Miranda.pdf: 1217281 bytes, checksum: bd45c2f7f20927f1da595dfd05965a6a (MD5) Previous issue date: 2013-02-20
Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
In Northeastern Brazil, in recent decades, with the increase of irrigation using in irrigated perimeters, often with inadequate management to local conditions, the soil salinization and sodification processes have intensified, promoting degradation and abandonment of large areas previously productive. Thus, we carried out a field survey to investigate the soil degradation in irrigated perimeter situated in the municipality of Custodia, semiarid region in Pernambuco, Brazil. Firstly were identified areas with degraded soils by salts excess, and also was done the experiment assembly with the intent to recover those areas through the application of organic and chemicals compounds, besides the technique of phytoremediation with Atriplex nummularia. For that, soil samples were taken in all 55 plots that make up the perimeter in the 0-10, 10-30 and 30-60 cm layers for the soils physical and chemical characterization, and chemical analyzes of the water used on the perimeter during periods of July/2009, January/2010, July/2010 and January/2011. After the selection of the degraded area into the irrigated perimeter, was mounted an experiment to recover the degraded soil by the evaluation of the treatments: 1) planting of Atriplex nummularia Lindl, 2) application of bovine manure, 3) sheep manure, 4) polymer, 5) gypsum and 6) control (witness). Four samples were taken, the first being at the same time of the experiment assembly (October 2009). After that, three more samples were taken, at six (April 2010), twelve (October 2010) and eighteen months (April 2011) after experiment assembly. Soil samples were collected at 0-10, 10-30 and 30-60 cm depth for the chemical analyzes. To evaluate the physical properties, soil samples were collected in the first (October 2009) and in the last (April 2011) collection at 0-10 and 10-30 cm layers. Were monitored the soil attributes in relation to treatment application with respect to time. The soils of the irrigated perimeter from Custódia are in the process of degradation and need to have their properties monitored over time to prevent its development. Among the cations evaluated, soluble and exchangeable Na+ was what was in higher concentrations, followed by the Cl- and by the RAS variable, besides increasing the PST in depth. The phytoremediation technique was effective in improving the soils quality and the application of sheep manure and polyacrylamide based polymer also acted positively in improving the quality of soil chemistry and physics.
Na Região Nordeste do Brasil, nas últimas décadas, com o incremento da irrigação em perímetros irrigados, muitas vezes com manejo inadequado às condições locais, os processos de salinização e sodificação de solos têm se intensificado, promovendo a degradação e abandono de extensas áreas anteriormente produtivas. Assim, realizou-se o levantamento da situação de degradação do Perímetro Irrigado de Custódia, no Sertão de Pernambuco, onde foram identificadas áreas com problemas de excesso de sais, seguindo-se de montagem de experimento para recuperação de uma dessas áreas, através da aplicação de compostos orgânicos e químicos, além da técnica da fitorremediação com Atriplex nummularia. Para isso, foram realizadas amostragens de solos em todos os 55 lotes que compõem o perímetro nas profundidades de 0-10, 10-30 e 30-60 cm para a caracterização física e química dos solos, além das análises químicas das águas utilizadas no perímetro nos períodos de Julho/2009, Janeiro/2010, Julho/2010 e Janeiro/2011. Após seleção de área degradada do perímetro, foi montado experimento de recuperação do solo testando-se os tratamentos: 1) plantio de Atriplex nummularia Lindl, 2) aplicação de esterco bovino, 3) esterco ovino, 4) polímero, 5) gesso e 6) controle (testemunha). Foram realizadas quatro amostragens, sendo a primeira no momento da montagem do experimento (Outubro de 2009), aos seis (Abril de 2010), aos doze (Outubro de 2010) e aos dezoito meses (Abril de 2011). As amostras de solo foram coletadas nas camadas de 0-10, 10-30 e 30-60 cm de profundidade para realização das análises químicas. Para a realização das análises físicas do solo coletaram-se amostras de solo na primeira coleta (Outubro de 2009) e na ultima (Abril de 2011) nas profundidades de 0-10 cm e 10-30 cm. Foram monitorados os atributos do solo com a aplicação dos tratamentos em função do tempo. Os solos do Perímetro Irrigado de Custódia encontram-se em processo de degradação e precisam ter suas propriedades monitoradas ao longo do tempo para evitar sua evolução. Entre os cátions avaliados, o Na+ solúvel e trocável foi o que esteve em concentrações mais elevadas, seguido pelo Cl- e pela variável RAS, além do aumento da PST em profundidade. A técnica da fitorremediação foi efetiva na melhoria da qualidade dos solos estudados e a aplicação do esterco ovino e do polímero a base de poliacrilamida também atuaram positivamente na melhoria da qualidade química e física do solo.
47
Bičius, Žydrūnas. "Organinių azoto trąšų „Provita“ įtaka ekologiškai auginamų bulvių derlingumui, derliaus kokybei ir dirvožemio savybėms." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090608_123352-64507.
Full textAbstract:
2008 m. Lietuvos žemės ūkio universiteto Bandymų stotyje atlikus organinių azoto trąšų Provita įtakos ekologiškai auginamoms bulvėms tyrimus, nustatyta, kad tręšimas organinėmis azoto trąšomis Provita, bei organinių azoto trąšų Provita deriniais su Patenkali ir fosforitmilčiais esminiai padidino bulvių suminį ir prekinį derlingumą bei derliaus prekingumą. Patręšus Provita, Patenkali ir fosforitmilčiais bei Provita ir Patenkali esminiai padidėjo suminis ir prekinis bulvių derlingumas, lyginant su tręšimu Provita bei Provita ir fosforitmilčių trąšų deriniu. Bulves patręšus Provita, Provita ir Patenkali bei Provita, Patenkali ir fosforitmilčiais esminiai sumažėjo bulvėse krakmolo, lyginant su netręštomis bulvėmis. Patręšus bulves organinėmis azoto trąšomis Provita esminiai sumažėjo sausųjų medžiagų bulvių gumbuose, lyginant su netręštomis bulvėmis bei tręšimu Provita, kalio ir fosforo trąšų deriniais. Tręšiant organinėmis azoto trąšomis Provita gautas neigiamas azoto balansas. Tręšimas N60 organinių azoto trąšų norma, neužtikrino teigiamo azoto balanso dirvožemyje.Research on the effect of organic nitric fertilizers Provita to organically cultivated potatoes performed in 2008 at the experimental station of Lithuanian University of Agriculture highlighted, that fertilization of potatoes with organic nitric fertilizers Provita, as well as combinations of organic nitric fertilizers Provita with Patenkali and phosphorite powder, significantly increased total and marketable harvest of potatoes, as well as merchantability of harvest. In case of fertilization with Provita, Patenkali and phosphorite powder, as well as Provita and Patenkali, total and marketable harvest of potatoes was significantly increased, compared with fertilization using Provita and the combination of Provita and phosphorite powder. After fertilization of potatoes with Provita, Provita and Patenkali as well as Provita, Patenkali and phosphorite powder, the concentration of starch in potatoes was significanlty lower, than in these never fertilized. After fertilization of potatoes with organic nitric fertilizers Provita, the concentration of dry matterial in potatoes was significantly decreased, compared to these never fertilized, or fertilized with Provita, combinations of kalium and phosphoric fertilizers. Fertilization of potatoes had no significant effect to the concentration of soluble dry matterial in potatoes. Fertilization with organic nitric fertilizers Provita resulted in negative nitric balance. Fertilization with standard volume of organic nitric fertilizers N... [to full text]
48
Ponthieux, Sylvain. "Synthèse et réactivité des β-phénylsélanyl énoxysilanes." Rouen, 1997. http://www.theses.fr/1997ROUES058.
Full textAbstract:
Une méthode efficace de sélénénylation, à l'aide de trichlorure de benzèneséléniényle, d'aldéhydes et de cétones, ayant un carbone α-méthylénique, est décrite. La transformation des composés α-séléniés obtenus en β-phénylsélanyl énoxysilanes est réalisée principalement à l'aide du couple triéthylamine-chlorotriméthylsilane en solution dans le tétrahydrofurane, à température ambiante. La stéréochimie, des éthers d'énols silylés dérivés de phénylsélanylméthyl cétones, est déterminée par les constantes de couplage 2J[SeHβ], 1J[SeCβ] et la différence de déplacement chimique des carbones α et β. La réaction de double α-phénylsélénénylation est réalisée selon trois procédures adaptées à l'état de substitution des cétones initiales. La réaction d'allylation et de benzylation des β-phénylsélanyl énoxysilanes est étudiée. La génération des énolates α-phénylsélénies in situ est réalisée par coupure de la liaison oxygène-silicium, au moyen du t-butylate de potassium, en solution dans un mélange t-butanol-dichlorométhane. L'alkylation compétitive au niveau de l'atome de sélénium est prouvée avec la formation d'alkyl phénylsélénoéthers. La réaction d'aldolisation croisée des énoxysilanes, dérivés de phénylsélanylméthyl cétones, avec le benzaldéhyde, catalysée par l'éthérate de trifluorure de bore, a conduit à des aldols syn quelle que soit la proportion des isomères géométriques des énoxysilanes. La formation des énolates, par le fluorure de tétrabutyl ammonium, mène à un mélange d'aldols syn et trans. Deux mécanismes sont proposés pour expliquer la formation d'un époxyde trans à partir d'un aldol syn. La réduction de ces aldols en syn, syn-2-phénylsélanyl-1,3-diols, la formation d'-phénylsélanyl énones et la synthèse d'éthers triméthylsilyles à partir de ces aldols séléniés sont également décrites. Le mécanisme de réarrangement α,α' de certaines α-phénylsélanyl cétones ainsi que le caractère sélénophile des énolates dérivés ont été étudiés.
49
Laniel, Dominique. "Synthèse de polymères d'azote par pression comme matériaux énergétiques du futur." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS472.
Full textAbstract:
L’objectif de cette thèse doctorale fut la synthèse de composés polyazotés qui serviraient comme matériaux énergétiques du futur. Afin d’y arriver, les propriétés physico-chimiques de l’azote pur ainsi que des mélanges binaires xénon-azote, hydrogène-azote ainsi que lithium-azote furent étudiés à des pressions et températures extrêmes. Lors de la compression de l’azote pur jusqu’à environ 250 GPa et chauffé à 3300 K, une nouvelle forme d’azote polymérique constituée d’anneaux N6 interconnectés fut obtenue. À basse pression, les études du mélange Xe-N2 permirent de découvrir un composé de van der Waals de stoechiométrie Xe(N2)2. À plus haute pression et température (150 GPa et 2500 K) un solide composé de xénon et d’azote simplement lié fut obtenu. L’étude du système N2-H2 se focalisa sur le composé N2(H2)2. Sa structure complexe fut déterminée et, une réaction chimique vers 50 GPa ayant comme produit de réaction des azanes (NxHx+2) fut mise à jour. Il fut constaté que l’azane ammoniac (NH3), principalement obtenu, se transforme en hydrazine (N2H4)—pourtant a priori moins stable thermodynamiquement—lors de la décompression des échantillons réagit. Enfin, l’étude du système Li-N2 révéla une chimie remarquable entre ces deux éléments. Une grande variété d’anions d’azote fut obtenue, notamment N3-, [N2]~2 [N2]~1 et N5-. En particulier, le pentazolate de lithium (LiN5), contenant l’anion pentazolate hautement énergétique, put être récupéré aux conditions ambiantes. Ce composé est le premier composé polyazoté à haute densité d’énergie produit par pression et récupéré aux conditions ambiantes, démontré le potentiel des synthèses hautes pressions pour ce type de matériauThe goal of this thesis is to synthesize novel polynitrogen compounds by pressure as the next-generation high energy density materials (HEDM). To achieve this, the physico-chemical properties of pure nitrogen as well as the xenon-nitrogen, hydrogen-nitrogen and lithium-nitrogen mixtures were studied under extreme pressure and temperature conditions. In the case of the compression of pure nitrogen, a novel polymeric nitrogen solid composed of interconnected chains of N6 rings was produced at 250 GPa and 3300 K. The low pressure Xe-N2 investigation revealed the formation of a stoichiometric Xe(N2)2 van der Waals compound. Above 150 GPa and 2500 K a xenon-polynitrogen material was observed. The N2-H2 study, focusing on the characterization and high-density behavior of the N2(H2)2 van der Waals compound, uncovered its pressure-induced chemical reaction near 50 GPa into azanes (NxHx+2), with ammonia (NH3) as the main constituent. Intriguingly, decompression of the reacted sample resulted, below 10 GPa, in the transformation of ammonia into its thermodynamically less stable counterpart hydrazine (N2H4). Lastly, the Li-N2 system proved to be of great interest due to the large array of anionic nitrogen moieties discovered (N3-, [N2]~2 [N2]~1 and N5-). In particular, lithium pentazolate (LiN5), containing the elusive energetically-rich pentazolate anion, was synthesized above 45 GPa and 2500 K. Moreover, it could be retained down to ambient conditions. It is the first polynitrogen HEDM produced by high pressure and retrieved down to ambient conditions. These results demonstrate the potential of high pressure for the synthesis of industrially relevant HEDM
50
Bédat, Joëlle. "Synthèses et études spectroscopiques de modèles biomimétiques chiraux du NADH : évaluation des facteurs conformationnels qui gouvernent le transfert énantiosélectif de l'hydrogène." Rouen, 1995. http://www.theses.fr/1995ROUES024.
Full textAbstract:
L'objectif de ce travail était d'évaluer les paramètres importants responsables des excès énantiomériques obtenus par des modèles biométiques chiraux du NADH. Cette stéréodifférenciation serait le fruit d'une synergie entre l'orientation de la fonction carbonyle et l'encombrement stérique du à l'auxiliaire chiral. Cette étude nous a, de plus, permis d'élaborer deux des modèles chiraux du NADH les plus performants en synthèse asymétrique. Dans une seconde partie, nous avons envisagé la synthèse de modèles plus stables et plus réactifs en série benzo[b]naphthyridine et indolo[2,3-b]pyridine