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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
291

Variáveis que influenciam a estabilidade da alvura de polpas branqueadas em sequências ECF /

Camargo, Sâmique Kyene de Carvalho Araújo. January 2017 (has links)
Orientador: Gustavo Ventorim / Banca: Cristiane Inácio de Campos / Banca: Claudia Andeli Sansigolo / Resumo: O branqueamento objetiva a remoção de compostos que dão cor à polpa: lignina, extrativos, grupos carbonilas e carboxilas, complexo lignina carboidrato (LCC's) e metais, para atingir a alvura mínima de 90± 0,5% ISO, exigida para comercialização da polpa e esta deve se manter estável em todo processo que compreende o transporte, manuseio e armazenamento, até o consumidor final. A utilização de diferentes reagentes de branqueamento efetiva a melhor eficiência na remoção destes compostos e, consequentemente, melhoram a estabilidade da alvura. O objetivo deste trabalho é avaliar o efeito das diferentes sequências de branqueamento na remoção dos grupos cromóforos, especialmente dos grupos carbonilas, minimizando assim a reversão de alvura. Para isso utilizou-se a espectroscopia na região do infravermelho. Também foi avaliado o efeito do pH nos estágios finais de branqueamento na estabilidade da alvura. Os experimentos foram realizados no Laboratório de Celulose da Unesp de Itapeva, onde foi efetuado o branqueamento das polpas de celulose deslignificada com oxigênio em sacos de polietileno, e para controle da temperatura utilizou-se o banho termostatizado. As sequências de branqueamento estudadas foram: D0(E+P)D1D2, AHTD0(E+P)D1D2, AHTD0(E+P)D1P, AHTD0(PO)D1, e AHTD0(PO), após o branqueamento foram efetuadas as análises de alvura, viscosidade e reversão de alvura. O efeito do pH na estabilidade da alvura pôde ser observado variando o pH do estágio final na faixa de 3 a 10 e efetuand... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The bleaching process aims at the removal of compounds that give color to the pulp: lignin, extractives, carbonyl and carboxyl groups, lignin carbohydrate complex (LCC's) and metals, in order to reach the minimum whiteness of 90 ± 0.5% ISO, required for the commercialization of pulp And it must remain stable throughout the process, including transportation, handling and storage, to the final consumer. The use of different effective bleaching reagents gives better efficiency in the removal of these compounds and, consequently, enhances the brightness stability. The objective of this work is to evaluate the effect of the different bleaching sequences on the removal of the chromophore groups, especially the carbonyl groups, thus minimizing the reversal of whiteness. And, for that, spectroscopy was used in the infrared region. The effect of pH in the final stages of bleaching on brightness stability was also evaluated. The experiments were carried out at the Pulp Laboratory of Unesp de Itapeva, where the pulps of cellulose pulp were delignified with oxygen in polyethylene bags and the thermostated bath was used to control the temperature. The bleaching sequences studied were D0(E+P)D1D2, AHTD0(E+P)D1D2, AHTD0(E+P)D1P, AHTD0(PO)D1, and AHTD0(PO). After bleaching, of whiteness, viscosity and reversal of whiteness. The effect of pH on the brightness stability could be observed by varying the pH of the final stage in the range of 3 to 10 and effecting the induced reversal. The analysis by infrared spectroscopy proves the efficiency of the reagents in the removal of carbonyl groups, because with the use of hydrogen peroxide in the final stages P and PO there was a decrease in the intensity of the absorption band in the infrared region of these groups. It could be seen from this study that acid hydrolysis(Complete abstract click electronic access below) / Mestre
292

Métodos computacionais no estudo de fármacos / Computational methods in the study of drugs

Alves, Daniel de Matos January 2011 (has links)
ALVES, Daniel de Matos. Métodos computacionais no estudo de fármacos. 2011. 145 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2011. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-04-28T21:20:43Z No. of bitstreams: 1 2011_tese_dmalves.pdf: 1682699 bytes, checksum: 23802c487f6a1c08293b04b6fea1611c (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-04-29T17:50:20Z (GMT) No. of bitstreams: 1 2011_tese_dmalves.pdf: 1682699 bytes, checksum: 23802c487f6a1c08293b04b6fea1611c (MD5) / Made available in DSpace on 2015-04-29T17:50:20Z (GMT). No. of bitstreams: 1 2011_tese_dmalves.pdf: 1682699 bytes, checksum: 23802c487f6a1c08293b04b6fea1611c (MD5) Previous issue date: 2011 / In this work we performed ab initio calculations on two drugs, benzonidazole and mebendazole, used on the treatment of parasitic infections. The calculations were divided into obtaining the vibrational modes Raman and infrared spectra, molecular dynamics and calculation of the potential energy distribution. We developed the software PEDCALC to calculate the potential energy distribution and classify the vibrational modes. The classification of the vibrational modes is done by comparing the calculated spectra with experimental spectra and the potential energy distribution. We showed that software PEDCALC can produce accurate results of the potential energy distribution, and it is essential tool in the classification of vibrational modes of any molecule. We performed molecular dynamics calculations in the dimer of mebendazole to show the exchange of hydrogen atoms between its monomers, so we observed the dynamics of the tautomerism of this molecule. / Nesse trabalho realizamos cálculos ab initio em dois fármacos, benzonidazol e mebendazol, usados no combate de infecções por parasitas. Os cálculos foram divididos em obtenção dos espectros vibracionais Raman e infravermelho, dinâmica molecular e cálculo da distribuição da energia potencial. Desenvolvemos o software PEDCALC para calcular a distribuição da energia potencial e classificar os modos de vibração. A classificação dos modos de vibração é realizada pela comparação dos espectros calculados com espectros experimentais e a distribuição da energia potencial. Mostramos que o software PEDCALC pode produzir resultados exatos da distribuição da energia potencial, e, é ferramenta essencial na classificação dos modos de vibração de qualquer molécula. Realizamos cálculo de dinâmica molecular no dímero de mebendazol para mostrar a troca de átomos de hidrogênio entre seus monômeros, observamos assim a dinâmica do tautomerismo dessa molécula.
293

Estudo das propriedades vibracionais do diterpeno C20H28O4 e da xantoxilina C10H12O4, por espectroscopias FT-Raman, FT-IR e cálculos DFT / Study of vibrational properties of diterpene C20H28O4 and of xantoxilina C10H12O4 by FT-Raman spectroscopy, FT-IR and cálculos DFT

Silva, Cristiano Balbino da January 2012 (has links)
SILVA, Cristiano Balbino da. Estudo das propriedades vibracionais do diterpeno C20H28O4 e da xantoxilina C10H12O4, por espectroscopias FT-Raman, FT-IR e cálculos DFT. 2012. 119 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2012. / Submitted by Edvander Pires (edvanderpires@gmail.com) on 2015-10-20T20:04:38Z No. of bitstreams: 1 2012_dis_cbsilva.pdf: 5017214 bytes, checksum: c710995a46a14065f6d077b27264f5fb (MD5) / Approved for entry into archive by Edvander Pires(edvanderpires@gmail.com) on 2015-10-21T20:38:24Z (GMT) No. of bitstreams: 1 2012_dis_cbsilva.pdf: 5017214 bytes, checksum: c710995a46a14065f6d077b27264f5fb (MD5) / Made available in DSpace on 2015-10-21T20:38:24Z (GMT). No. of bitstreams: 1 2012_dis_cbsilva.pdf: 5017214 bytes, checksum: c710995a46a14065f6d077b27264f5fb (MD5) Previous issue date: 2012 / In this work we present results on vibrational properties of two organic substances that are used in popular medicine: diterpene C20H28O4, extracted from Croton argyrophyloides and xanthoxyline C10H12O4), extracted from Croton neptaefollius. In the present work we show Fourier Transform Raman spectroscopy (FT-Raman) measurements, as well as, Fourier Transform infra red (FT-IR) measurements, in order to obtain the vibrational normal modes of the two substances. Ab initio (first principle) calculations through density fuctional theory (DFT) and potential energy distribution (PED) were performed to assign the bands observed in both FT-Raman and FT-IR spectra. For diterpene, additionally, we performed Raman spectroscopy studies at low temperatures, 20 to 300K, in order to investigate evidence of a possible phase transition. However, the Raman spectra do not show significant changes, indicating that the diterpene crystalline structure is stable between 20 to 300K. / Neste trabalho foram estudadas as propriedades vibracionais de duas substâncias orgânicas, extraídas de plantas comumente usadas na medicina popular: o diterpeno C20H28O4, extraído do Croton argyrophylloides e a xantoxilina C10H12O4, extraída do Croton Nepetaefollius. Foram realizadas medidas de espectroscopia Raman por transformada de Fourier (FTRaman) e medidas de infravermelho por transformada de Fourier (FT-IR), para obtenção dos modos normais de vibração das substâncias. Cálculos ab initio (primeiros princípios), usando a Teoria do Funcional de Densidade (DFT, density funcional theory) e de distribuição de energia potencial (PED, Potential Energy Distribuiction), foram realizados para a identificação das bandas presentes nos espectros vibracionais das duas substâncias. Em relação diterpeno, adicionalmente, foram feitas medidas de espalhamento Raman a baixas temperaturas, entre as regiões de 20 e 300K, para investigar indícios de uma possível transição de fase. Os espectros Raman não apresentam mudanças significativas a baixas temperaturas, indicando que a estrutura cristalina do diterpeno é estável entre 20 e 300K.
294

Effect of spruce swamp forest drainage and restoration on soil organic matter quality

MASTNÝ, Jiří January 2013 (has links)
The aim of the study was to determine the effect of spruce swamp forest drainage and water regime restoration on soil organic matter (SOM) quality. Six localities of spruce swamp forests in Šumava Mountains were studied (2 drained, 2 restored and 2 pristine). SOM quality was affected by long-term drainage. Spruce swamp forest restoration (3-7 years) did not have significant effect on SOM quality although other parameters (pH, bulk density, water level, plant coverage) changed.
295

Changes in microvascular hematocrit during post-occlusive reactive hyperemia: descriptions and mechanisms

Bopp, Christopher Michael January 1900 (has links)
Doctor of Philosophy / Department of Anatomy and Physiology / Thomas J. Barstow / The primary aim of this dissertation was to describe the changes in microvascular hematocrit, as total[hemoglobin+myoglobin] (T[Hb+Mb] measured with near-infrared spectroscopy (NIRS), during post-occlusive reactive hyperemia (PORH). Mechanisms of reactive hyperemia within skeletal muscle were also explored. The investigation detailed in Chapter 2 of this dissertation found that the differing time courses of the kinetic responses of both oxy- and deoxy[Hb+Mb], are related to changes in T[Hb+Mb]. We also determined that adipose tissue thickness had no effect on a purely temporal analysis of NIRS data. In Chapter 3 we observed that brachial artery reactive hyperemia preceded changes in T[Hb+Mb] during reactive hyperemia. Assuming that myoglobin remained constant, we posited that changes in T[Hb+Mb] must reflect alterations in red blood cell concentration in the microvasculature, i.e., microvascular hematocrit. In Chapter 4 comparisons were made between brachial artery blood flow, cutaneous and skeletal muscle flux and T[Hb+Mb]. The conduit artery response was faster than the microvascular responses in all tissues. Within skeletal muscle, time to peak and the time constant for the on-kinetics were faster in T[Hb+Mb] compoared with intramuscular flux as measured with intramuscular laser-Doppler. We observed no differences in temporal responses between cutaneous and intramuscular measures and suggested that in a purely temporal analysis the cutaneous microvasculature could serve as an analog for the skeletal muscle microvasculature. Finally, in Chapter 5 we found that prostaglandin inhibition with ibuprofen altered the initial T[Hb+Mb] response during PORH without impacting cutaneous flux or brachial artery blood flow. Chapter 5 also discussed that the addition of a wrist cuff to our standard instrumentation prevented the accumulation of T[Hb+Mb] during the occlusion period.
296

Development of NIR spectroscopy models for starch content prediction and ethanol production from mutant grain sorghum

Saul, Kaelin E. January 1900 (has links)
Master of Science / Biological & Agricultural Engineering / Donghai Wang / The growing demands for renewable energy sources have led researchers to investigate other biomass sources, aside from maize. Grain sorghum is comparable to maize in its starch content and can be grown in regions with drier climates, where maize is a less suitable crop for these areas. In attempts to increase yield prior to harvest and for ethanol production, this study focuses on mutant grain sorghum. One hundred and nine mutant grain sorghum samples were analyzed for their chemical and physical properties and fermented into ethanol. The current method for starch analysis is time-consuming and tedious. Near infrared spectroscopy (NIR) models were developed as fast, cost-effective, and non-destructive methods for grain sorghum starch content analysis. Each mutated grain sorghum sample was scanned in a wavelength range from 4,000 to 10,000 cmˉ¹ as a whole grain and in flour form. Partial Least Squares (PLS) regression method was used for NIR model development. The coefficients of determination (R²) of 0.77 and 0.90 were achieved for starch content calibration and prediction models, respectively. This model demonstrates the possibility of a positive correlation between the actual and calculated values for starch content. Another PLS first derivative model with R² = 0.95 for calibration and a reduced wavelength range (4,000-5,176 cmˉ¹), using 39 of the original 109 samples (27 for calibration and 8 for validation), was created to predict the fermentation efficiency.
297

Desenvolvimento de compósitos expandidos poliuretânicos com fibra de celulose e pó de madeira para utilização como sorvente de óleo

Macedo, Vinícius de 09 June 2015 (has links)
Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2015-09-14T13:54:18Z No. of bitstreams: 1 Dissertacao Vinicius de Macedo.pdf: 206952 bytes, checksum: 8ba2c7fa36f986ee01378620029d7ca7 (MD5) / Made available in DSpace on 2015-09-14T13:54:18Z (GMT). No. of bitstreams: 1 Dissertacao Vinicius de Macedo.pdf: 206952 bytes, checksum: 8ba2c7fa36f986ee01378620029d7ca7 (MD5) / Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul.
298

Desenvolvimento de compósitos expandidos poliuretânicos com fibra de celulose e pó de madeira para utilização como sorvente de óleo

Macedo, Vinícius de 09 June 2015 (has links)
Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul.
299

Determinação dos parametros de qualidade de detergentes em po utilizando espectroscopia no infravermelho proximo / Determination of the parameters of quality of powder detergents using near infrared spectroscopy

Povia, Giovana Soato 30 May 2007 (has links)
Orientador: Celio Pasquini / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-09T09:59:17Z (GMT). No. of bitstreams: 1 Povia_GiovanaSoato_M.pdf: 1681817 bytes, checksum: d59818d169390e4a42e0555251507c27 (MD5) Previous issue date: 2007 / Resumo: Este trabalho visa o desenvolvimento de um método analítico para a determinação dos parâmetros de qualidade em detergentes em pó utilizando a Espectroscopia de Infravermelho Próximo (NIR) e técnicas de calibração multivariada. Foram utilizados dois conjuntos de amostras: o primeiro para as análises quantitativas e o segundo para análises qualitativas. As amostras do primeiro conjunto tiveram os parâmetros de qualidade determinados pelos respectivos métodos de referência. A técnica estatística utilizada para as calibrações foi o PLS. Foram desenvolvidos modelos de calibrações para a previsão do teor de umidade, matéria ativa e densidade. O desempenho dos modelos de calibrações foi avaliado por meio de validação externa. A determinação do teor de umidade apresentou RMSEP = 0,29% (m/m). O valor de RMSEP para a determinação da matéria ativa foi de 0,37% (m/m) e para a determinação da densidade o valor de RMSEP = 14 g L . Os modelos construídos apresentaram resultados satisfatórios e os erros encontrados são aceitáveis para a faixa de controle utilizada na indústria. O segundo conjunto é composto de 4 grupos, que apresentam características distintas. Foram avaliados dois métodos de classificação: SIMCA e PLS DA. É possível observar que ocorre a discriminação das amostras que apresentam teor de matéria ativa mais elevado, no entanto, os outros grupos não puderam ser discriminados. Os dois métodos de classificação avaliados apresentaram resultados semelhantes, com acerto de 100% na classificação de amostras externas somente em seus respectivos grupos / Abstract: This work aims the development of an analytical method for the determination of quality parameters on powder detergents using the near infrared spectroscopy (NIR) and multivariate calibration techniques. Two sets of samples were used: the first one for the quantitative analysis and the second one for qualitative analysis. The samples of the first set had the quality parameters determined by their respective methods of reference. The chemometric technique used for calibration was the PLS1. Calibrations for the prediction of de moisture content, active matter and density were developed. The performance of the calibration models was evaluated through external validation. The determination of the moisture content presented a RMSEP = 0,29% (w/w). The value of RMSEP for the determination of the active matter was 0,37% (w/w) and for the determination of moisture the value of RMSEP was 14 g L. The constructed models presented satisfactory results and the errors that were found are acceptable for the control range used in industry. The second set is composed of four groups of power detergents which present different characteristics. Two methods of classification were evaluated: SIMCA and PLS DA. It was possible to observe the discrimination of the samples which presents higher active matter content. However, the other groups could not be discriminated. Both methods of classifications evaluated presented similar results, with 100% correcte results of the classification of samples only in their respective groups / Mestrado / Quimica Analitica / Mestre em Química
300

Análise conformacional das 2-feniltio, 2-fenilsulfinil e 2-fenilsulfonil-N,N-dietilacetamidas e 2-feniltio, 2-fenilsulfinil e 2-fenilsulfonil-cicloexanonas 4\'-substituídas / Conformational analysis of 2-phenylthio; 2-phenylsulfinyl; 2- phenylsulfonyl N,N-diethylacetamides and 2-phenylthio; 2-phenylsulfonyl; 2- phenylsulfinyl cyclohexanones 4\'-substituted series

Elisângela Vinhato 03 April 2007 (has links)
A presente tese trata da síntese e a análise conformacional de seis séries de compostos: 2-feniltioN;N-dietilacetamidas 4\'-substituídas (I); 2-fenilsulfinil-N,N-dietilacetamidas 4\'-substituídas (II); 2-fenilsulfonil-N,N-dietilacetamidas 4\'-substituídas (III); 2-feniltio-cicloexanonas 4\'-substituídas (IV); 2-fenilsulfonil-cicloexanonas 4\'-substituídas (V); 2-fenilsulfinil-cicloexanonas 4\'substituídas (IV). O estudo conformacional foi realizado por intermédio das espectroscopias no IV e RMN de hidrogênio, apoiados por cálculos teóricos. A análise de vCO no infravermelho para as séries I, II e III, de forma geral, se correlaciona bem com os cálculos em HF e B3LYP os quais demonstram a ocorrência de duas conformações estáveis para os compostos da série (I), tendo o confôrmero gauche mais estável em relação ao confôrmero cis. O efeito dos substituintes da série (I), observado experimentalmente, é mais concordante com os resultados calculados em B3LYP do que em HF. Com relação à série (II), há apenas uma conformação estável, ou seja, a cis, no gás e em solventes de diferentes polaridades. A série (III) apresentou a existência de três conformações estáveis, sendo duas conformações gauche de maior estabilidade que a terceira conformação cis (no gás e no solvente de baixa polaridade: CCl4). Nas séries das cicloexanonas (IV, V e VI) a análise de vCO no infravermelho e RMN de hidrogênio apresentou a conformação axial como preferencial em CCl4, sendo que esta preferência passou para equatorial em CH3CN (CD3CN). Os cálculos ab initio (HF) reproduziram o resultado experimental em CCl4, apenas para os derivados 2-fenilsulfonil-cicloexanonas 4\'-substituídas (V). Por outro lado, para estas cicloexanonas (IV - VI) os cálculos em B3LYP estão mais concordantes com os dados experimentais. O método NBO (Natural Bond Orbital) confirmou que as conformações gauche das séries (I, II e III) são estabilizadas por pelas interações: nN/π*C=O, πC=O/σ*C-S, σC-S/π*C=O, n(S)/π*C=O, π*C=O/σ*C-S, e as séries (IV, V e VI) pelas interações πC=O/σ*C-S, σC-S/π*C=O, n(S)/π*C=O, π*C=O/σ*C-S. Em contraste, estes resultados de NBO demonstraram também a importância das interações: nO(CO)/σC-S, nO(CO)/σ*S-O e nO(CO)/σ*C-H para a estabilização da conformação cis. Adicionalmente, a análise das cargas calculadas sugeriu a participação de interações Coulombicas na estabilização das conformações cis e gauche. Para todas as séries de compostos (I - VI), os cálculos incluindo o efeito do solvente (Onsager e PCM), para alguns compostos representativos, facilitaram a atribuição de cada conformação em solução. / This thesis reports the synthesis and conformational analysis of six sedes of compounds: N,N diethyl-2-[( 4-substituted)phenylthio] acetamides (I); N,N-diethyl-2-[(4-substituted)phenylsulfinyl] acetamides (II); N,N-diethyl-2-[(4-substituted)phenylsulfonyl] acetamides (III); [4 = OMe, Me, H, Cl, Br and N02]; 2-[(4-substituted)phenylthio] cyclohexanones (IV); 2-[(4-substituted)phenylsulfonyl] cyclohexanones (V) and 2-[(4-substituted)phenylsulfinyl] cyclohexanones (VI), [4 = OMe, H and N02]. The conformational study was performed through the IR and 1H NMR spectroscopies, supported by theoretical calculations. The vCO infrared analysis for the series I, II and III in general matches well with the HF and B3LYP calculations which showed the occurrence of two stable conformations for compounds of series (I), being the gauche the most stable and the cis the second one. As for the substituent effect of series (I), the agreement between the experimental results with B3LYP is better than with HF. calculations. Considering the serries (II), there is only one stable conformation, the cis one, in gas and in solvents of different polarity. The series (III) showed the existence of three stable conformations, being the two gauche the most stable and the cis the least stable (both in the gas and in the low polarity solvent, CCl4). In the cyclohexanones series (IV, V and VI) the vCO infrared and 1H NMR analyses showed a preference for the axial conformation, in CCl4, changing the preference to equatorial one in CH3CN (CD3CN). The ab initio (HF) calculations reproduced the experimental preference, in CCl4, for the 2-[(4-substituted)phenylsulfonyl] cyclohexanones only. On the other hand, for these cyclohexanones (IV-VI) the B3LYP calculations improved the agreement with the experimental data. The NBO (Natural Bond Orbital) method confirmed that the gauche conformations of the series (I, II and III) are stabilized by: nN/π*C=O, πC=O/&#963*C-S, σC-S/π*C=O, n(S)/π*C=O, π*C=O/σ*C-S, and for the series (IV, V and VI) by the interactions: πC=O/σ*C-S, σC-S/π*C=O, N(S)/π*C=O, π*C=O/σ*C-S. In contrast these NBO results also revealed the importance of the interactions nO(CO)/σ*C-S, nO(CO)/σ*S-O and nO(CO)/σ*C-H for the stabilization of the cis conformation. Additionally, the calculated charge analysis suggested the stabilization of both cis and gauche conformations due to Coulombic interactions. The inclusion of the solvent effect in the computations (Onsager and PCM methods) for some representative compounds of series (I-VI) facilitated the conformer attribution in solution.

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