Topic I An empirical potential for calculating hydrogen bonding energies is developed for systems of the type A-H--B, where A and/or B is oxygen or nitrogen. Point charge and van der Waals interaction are included in the potential. The parameters of the potential were optimized by means of a simplex algorithm within a range of A-B distances from 2.8 A through 5.0 A. The root mean square deviation between the empirical potential and the ab initio results of 216 configurations of (H₂O)₂, (NH₃)₂ and NH₃•H₂O is 0.9 kcal/mol and 0.5 kcal/mol for 61 configurations of methanol dimers. Applications of the potential to water dimers, ammonia dimers, their mixed dimers, water oligomers and ice-h as well as the β form of the methanol crystal show that the potential yields reasonable results compared to those computed by "ab initio" methods using 6-31G* basis sets. The potential is compatible with MM2 program. It is simpler than earlier potentials in that neither dipoles nor Morse potentials are involved. It should be superior to the empirical potentials developed by Jorgensen that used STO-3G ab initio calculated results as the standards. The potential might be useful for estimation of hydrogen bond energies in a local part of a large molecule to avoid the prohibitive expense of ab initio calculation. Topic II The monoclinic anthracene crystal is used as an example to demonstrate the feasibility of optimizing the orientation of molecules in the unit cell by matching calculated and experimental refractivity ellipsoids using a simplex algorithm. The calculated refractivity ellipsoid is determined by use of an empirical formula using bond directional polarizabilities. Optimization of the molecular orientations to provide the best fit to the experimental ellipsoid starting from several assumed orientations results in fits for which the maximum deviation from the experimental molecular orientation was no more than 10 degrees. The method can be applied to other monoclinic molecular crystals directly and could be extended to other crystal systems with anisotropic optical properties. Topic III Three mechanisms (Walden inversion, addition-rearrangement-elimination and proton 1,3 shift mechanisms) of the following reaction were suggested by Jay et al. and Andrade et al. respectively. CH₃CN + C⃰N- = CH₃C⃰N + CN-. The mechanism of Walden inversion was determined to be the least likely one based on Andrade's MNDO results. Our calculations, based on 3-21G and 4-31G results, show the contrary result that the Walden inversion is the most likely mechanism among the three considered. However, solvation effects were neglected in the calculations and these effects could play a major role in the choice of mechanisms. Simple calculations based on Boltzmann distribution of precursor concentrations and the Arrhenius law show that Walden inversion predominates over Jay's addition-elimination-rearrangement mechanism even when MNDO energy levels were used. Estimated orders of magnitude for the rate ratios were determined. / Ph. D.

Gauge invariant shielding constants calculations of ?H, ?C, and ??N were calculated for acetonitrile in the gas and liquid phases. Dierent basis sets as well as dierent ab initio and DFT methods were tested to select a time-ecient level of theory with reasonable accuracy. The eect of nuclear motion on the shielding constants was also explored. To investigate solvent eects on the shielding constants of acetonitrile, dierent clusters were extracted from molecular dynamics simulations. Convergence to the experimental values varied for the dierent clusters. The geometry of the central molecule in a cluster played an important factor in reaching convergence. / Master of Science

This Ph.D. dissertation is focused on the investigation the structure of nitrile anion containing molecules and how the structure and reactivity of those molecules are affected by solvation and counter ion. A systematic approach was employed in this investigation, beginning with an evaluation of the accuracy of three commonly used model chemistries (Hartree-Fock (HF), Second-order Møller-Plesset perturbation theory (MP2), the Becke three-parameter exchange functional coupled with the nonlocal correlation functional of Lee, Yang, and Parr (B3LYP), all paired with the 6-31+G(d) basis set). A series of complexes of various cations with a number of explicit molecules of tetrahydrofuran (THF) and dimethyl ether (DME) were studied with these model chemistries and the results were compared, where possible, with experimental results. From this work, it was determined that the B3LYP models gave the most accurate results for the complexes in question. This work was then extended to acetonitrile anion containing complexes of solvent and cation. Based on the results of that extension, it was determined that cation size and charge density on the cation were critical factors in determining the structure of the acetonitrile anion molecule and in determining if the anion was metalated at the nitrogen or alpha-carbon position, with larger cations favoring carbon metalation and more significant deformation of the alpha-carbon from the expected sp2 hybridization. The final aspect of this dissertation was the determination of reaction coordinate energy profiles for a pair of substitution reactions involving nitrile anion containing cycloaliphatic molecules. The results of this study showed that, due to steric and kinetic factors, the axial products and transitions states associated with these reactions were favored, and that the degree of preference was kinetically controlled. / Bayer School of Natural and Environmental Sciences / Chemistry and Biochemistry / PhD / Dissertation

Electrochemical potentials of a series of anthraquinone derivatives were studied in both aqueous solution and acetonitrile. The long term goal of this work was to find derivatives which could be reduced easily for studies of photoinduced electron transfer in DNA. Our immediate goal was to find the substitution group that gave the least negative redox potential value. Of all derivatives studied, the anthraquinone imides as a class had the least negative redox potentials, in the range of -0.600 to -0.550 V vs. SCE. One of the anthraquinones studied, one derivative (deoxyadenosine conjugated with an ethynyl linker to an anthraquinone with two ester substituents) was also in this range. A study of a series of anthraquinones conjugated with ethynyl and ethanyl linkers showed that the ethynyl linker was more effective than the ethanyl linker in lowering the redox potential of anthraquinone.

Tyrimo objektas ir metodai: tiriamieji antidepresantai: bušpirono hidrochloridas; sertralino hidrochloridas; amitriptilino hidrochloridas, fluvoksamino maleatas ir paroksetino hidrochloridas. Šių antidepresantų mišinio skirstymui ir komponentų identifikavimui plonasluoksnės chromatografijos metodu naudoti tirpikliai ir ryškinimo reagentai: metanolis, 25 proc. amonio hidroksidas, trichlormetanas, etanolis, etilacetatas, cikloheksanas, etano rūgštis, dimetilacetonas, acetonitrilas, propanolis, trifluoracto rūgštis, dichlormetanas, 1,4–dioksanas, benzenas, petrolio eteris, izoamilo spiritas, dietileteris, oktanas, metano rūgštis, N,N –dimetilanilinas, nitrobenzenas ir heksanas; Dragendorfo reagentas (modifikuotas pagal Munjė), ninhidrinas, Mandelino reagentas ir UV spinduliuotė (254 nm; 365 nm). Darbo tikslas: sukurti ir validuoti plonasluoksnės chromatografijos metodiką, tinkamą išskirstyti antidepresantų mišinio (amitriptilino hidrochloridas, paroksetino hidrochloridas, sertralino hidrochloridas, fluvoksamino maleatas ir bušpirono hidrochloridas) komponentus ir juos identifikuoti. Darbo uždaviniai: atlikti mokslinės literatūros šaltinių analizę įvertinant amitriptilino, paroksetino, sertralino, fluvoksamino ir bušpirono fizines, chemines, farmakologines savybes ir analizės metodus naudojamus jiems identifikuoti. Aprašyti skirtingas plonasluoksnės chromatografijos metodikas, tinkamas amitriptilino, paroksetino, sertralino, fluvoksamino ir bušpirono mišinio skirstymui ir... [toliau žr. visą tekstą] / Object and methods: research antidepressants: buspirone hydrochloride, sertraline hydrochloride, amitriptyline hydrochloride, fluvoxamine maleate and paroxetine hydrochloride. Used solvents and visualization reagents for those antidepressant mixture distribution and component identification by thin-layer chromatography: methanol, 25 percent. ammonium hydroxide, trichloromethane, ethanol, ethyl acetate, cyclohexane, ethane acid, dimethylketone, acetonitrile, propanol, trifluoroacetic acid, dichloromethane, 1,4-dioxane, benzene, petroleum ether, isoamyl alcohol, diethyl ether, octane, methane acid, N, N - dimethylaniline, nitrobenzene and hexane; Dragendorff reagent (modified by Munjė), ninhydrin, Mandelina reagent and UV radiation (254 nm; 365 nm). Aim: to develop and validate a thin-layer chromatographic method suitable for separating of antidepressants mixture components (amitriptyline hydrochloride, paroxetine hydrochloride, sertraline hydrochloride, fluvoxamine maleate and buspirone hydrochloride) and identify them. Objective: to perform analysis of scientific literature suporting amitriptyline, paroxetine, sertraline, fluvoxamine and buspirone physical, chemical, pharmacological properties, and analytical methods used to identify them. Describe the different thin-layer chromatographic techniques suitable for amitriptyline, paroxetine, sertraline, fluvoxamine and buspirone mixture distribution and component identification. Create a suitable thin-layer chromatographic... [to full text]

Submitted by ALINE CARVALHO MARTINS null (alinecarvalhomartins@hotmail.com) on 2016-02-29T01:32:05Z No. of bitstreams: 1 Tese defesa com correções.pdf: 2266757 bytes, checksum: a86bbd4a6396a41dc83d25dac4029acf (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-02-29T16:45:46Z (GMT) No. of bitstreams: 1 martins_ac_dr_jabo.pdf: 2266757 bytes, checksum: a86bbd4a6396a41dc83d25dac4029acf (MD5) / Made available in DSpace on 2016-02-29T16:45:46Z (GMT). No. of bitstreams: 1 martins_ac_dr_jabo.pdf: 2266757 bytes, checksum: a86bbd4a6396a41dc83d25dac4029acf (MD5) Previous issue date: 2016-01-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O monepantel, anti-helmíntico de uma nova classe, foi desenvolvido e colocado no mercado recentemente, como solução para criações com helmintos de ovinos multirresistentes. Após pouco tempo de utilização, foram relatados casos de resistência contra o produto. Objetivou-se avaliar o perfil de resistência ao monepantel em criações de ovinos em uma microrregião em torno de Jaboticabal-SP e caracterizar experimentalmente a resistência ao monepantel em isolado de Haemonchus contortus. Foi realizado o teste de redução de ovos em dez propriedades ovinocultoras próximas a Jaboticabal/SP, identificando a eficácia do monepantel e levantando o histórico da utilização do produto para determinação de fatores de risco associados à resistência. Obteve-se isolado de H. contortus resistente para teste crítico. Após coleta de fezes dos animais oriundos de propriedade onde o vermífugo foi ineficaz, obteve-se larvas infectantes que foram inoculadas em dois doadores para obtenção de fêmeas de H. contortus. Larvas infectantes deste isolado foram inoculadas em dez animais. Após confirmada a patência, cinco animais receberam monepantel, grupo tratamento, e cinco não receberam, grupo controle. Exames de OPG foram realizados nos dias 0 (dia do tratamento), 2, 4, 6, 8, 10, 12 e 14 e os animais eutanasiados no dia 14, avaliando o número de H. contortus no abomaso dos animais dos dois grupos. Revelou-se que em duas propriedades o monepantel foi ineficaz, em duas foi eficaz e nas outras seis foi altamente eficaz. Os principais fatores predisponentes detectados foram: intervalos curtos entre vermifugações, não alternância com outras bases químicas, tratamento massivo, raça e intensificação da criação. Observou-se H. contortus resistente após realização do teste crítico com eficácia de 24,65%. Conclui-se que helmintos de ovinos já estão resistentes ao monepantel em criações brasileiras localizadas no estado de São Paulo, especialmente o H. contortus. / Monepantel, anthelmintic of a new class, was recently developed and released to the international market, it was presented as a solution for properties with multirresistant helminthes. However, with little time utilization, were related cases of resistance against this product. The objectives of this work were evaluate the resistance profile of monepantel on sheep creations at a microregion around Jaboticabal-SP and characterize experimentally the monepantel resistance on Haemonchus contortus isolate. Initially, was accomplished egg count reduction test at ten ovine properties located around Jaboticabal-SP, identifying the monepantel efficacy and investigating the history of product use for determination risk factors resistance associated. Posteriorly, a H. contortus resistant isolate was obtained for the critic test. After animals collect stoll of a resistance suspected proprierty, there were obtained infective larvae that were inoculated on two donors for females of H. contortus obtainment and after, infective larvae production for inoculation in ten animals. After patency confirmed, five animals received monepantel, treatment group, and five didn’t receive, control group. The treatment day was day 0. Fecal egg counts were performed on days 0, 2, 4, 6, 8, 10, 12 and 14 and the animals were euthanized on day 14, evaluating the H. contortus number in the sheep abomaso of both groups. The results of the fisrt part study revealed the monepantel was ineffective in two properties, was effective in two properties and highly effective on six properties. The risk factors detected were: short interval between anthelmintic treatments, no alternation with other chemical bases, massive treatment, breed, intensification of creation. In a second step, was observed H. contortus resistant after performed the critc test, with an efficacy of 24,65%. We concluded that sheep helminths are already monepantel resistant in brazilian creations located at São Paulo state, especially Haemonchus contortus.

Master of Science / Food Science Institute / J. Scott Smith / Food irradiation is one of the most important food processing methods utilized to reduce microbial load and extend shelf life. In 1995 the World Health Organization (WHO) declared irradiated foods to be safe from a nutritional and toxicological point of view. Various methods have been applied to detect irradiated foods. Detection of 2-alkylcyclobutanones has been found to be a useful method in identifying irradiated foods. The solvent extraction method utilizes a Soxhlet apparatus for lipid extraction followed by clean up with Florisil. However, this method is very time consuming. The other methods available to detect 2-alkylcyclobutanone include supercritical fluid extraction (SFE), and accelerated solvent extraction method using a Dionex ASE 200 instrument. The SFE is a fast method to detected 2-alkylcyclobutanone. All the above mentioned methods involve costly equipment. The aim of this study was to eliminate the requirement of costly extraction equipment for lipid extraction before clean up or direct isolation of 2-alkylcyclobutanone as in case of SFE instrument using Florisil cartridges. In this study, the manual solvent extraction method was applied to isolate alkylcylcobutanone followed by clean up with 2 g silica cartridge. The clean up extract was injected to gas chromatography-flame ionization detector (GC-FID) for detection of 2-dodecylcyclobutanone (2-DCB). Gas chromatography-mass spectrometry (GC-MS) was used to confirm that the compound detected was 2-dodecylcyclobutanone. The ions m/z 98 and 112 were selected for 2-DCB for monitoring in selected ion monitoring (SIM) mode of GC-MS. The results showed that this method was able to detect 2-DCB from irradiated ground beef. The manual method does not require costly equipment such as supercritical fluid extractor, Dionex, or Soxlet apparatus for extraction process.

No description available.

Acetic anhydride hydrolysis in water is considered a standard reaction for investigating activation energy parameters using cosolvents. Hydrolysis in water/acetonitrile cosolvent is monitored by measuring pH vs. time at temperatures from 15.0 to 40.0 °C and mole fraction of water from 1 to 0.750. This work utilizes a temperature controlled water bath and a Vernier glass-body pH probe with Vernier Logger Pro 3.10.1 software for automated data collection. Data analysis is used to determine observed kinetic rate constants under the assumption that hydrolysis is a pseudo-first-order reaction. Eyring plots were used to compare activation energy parameters under iso-mole fraction conditions. The hydrolysis reaction of acetic anhydride was enthalpically stabilized and entropically destabilized at mole fractions of acetonitrile greater than 0.17 and the reverse occurred at mole fractions less than 0.17. Activation enthalpy and entropy result in the reaction being less favorable to form products as mole fraction of acetonitrile increased.

No description available.