No description available.

Cheung Chung Hong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 126-137). / Abstracts in English and Chinese. / ABSTRACT (English version) --- p.iii / ABSTRACT (Chinese version) --- p.vi / ACKNOWLEDGMENTS --- p.viii / TABLE OF CONTENTS --- p.ix / LIST OF FIGURES --- p.xiii / LIST OF TABLES --- p.xvii / Chapter CHAPTER ONE: --- INTRODUCTION --- p.1 / Chapter 1.1 --- Molecular Structure Determination --- p.1 / Chapter 1.2 --- Methods for Structure Determination --- p.1 / Chapter 1.2.1 --- Infrared (IR) Spectroscopy --- p.1 / Chapter 1.2.2 --- Electron Microscopy (EM) --- p.2 / Chapter 1.2.3 --- X-ray Diffraction (XRD) --- p.2 / Chapter 1.2.4 --- Nuclear Magnetic Resonance (NMR) Spectroscopy --- p.3 / Chapter 1.3 --- Solid State NMR Spectroscopy 一 Chemical Shielding Tensor --- p.4 / Chapter 1.4 --- Scope of This Thesis --- p.6 / Chapter CHAPTER TWO: --- PRINCIPLE AND THEORY --- p.7 / Chapter 2.1 --- Introduction --- p.7 / Chapter 2.2 --- Chemical Shielding Tensor (CST) --- p.7 / Chapter 2.2.1 --- Basis of Nuclear Magnetic Resonance --- p.7 / Chapter 2.2.2 --- Theoretical Description of CST --- p.8 / Chapter 2.3 --- CST Calculation --- p.11 / Chapter 2.3.1 --- Ramsey's Theory --- p.11 / Chapter 2.3.2 --- Gauge-including Atomic Orbitals (GIAO) Method --- p.13 / Chapter 2.4 --- Density Functional Theory (DFT) --- p.14 / Chapter 2.4.1 --- KS Theorem --- p.14 / Chapter 2.4.2 --- B3LYP - Hybrid DFT Functional --- p.16 / Chapter 2.5 --- Molecular Mechanic (MM) --- p.16 / Chapter 2.5.1 --- Basis Principle 一 Ball and Spring Model --- p.16 / Chapter 2.5.2 --- MM+ --- p.18 / Chapter 2.5.2.1 --- Bond Stretching --- p.18 / Chapter 2.5.2.2 --- Bond Bending --- p.19 / Chapter 2.5.2.3 --- Torsional Motion --- p.19 / Chapter 2.5.2.4 --- van der Waals Interaction --- p.19 / Chapter 2.5.2.5 --- Electrostatic Interaction --- p.20 / Chapter 2.5.2.6 --- Stretching-bending Interaction --- p.21 / Chapter 2.6 --- Isodesmic Reaction --- p.21 / Chapter CHAPTER THREE: --- METHODOLOGY AND EVALUATION --- p.23 / Chapter 3.1 --- Introduction --- p.23 / Chapter 3.2 --- Computational Method --- p.24 / Chapter 3.2.1 --- Evaluation of Different NMR Computation Level --- p.24 / Chapter 3.2.2 --- Computational Error 一 Round Off Error --- p.32 / Chapter 3.3 --- Local Structure Determination and Evaluation --- p.34 / Chapter 3.3.1 --- Methodology --- p.34 / Chapter 3.3.2 --- Definition of Local Structure --- p.37 / Chapter 3.3.3 --- Models used in Local Structure Determination --- p.37 / Chapter 3.3.3.1 --- Model without CST Modification (Mod-1) --- p.38 / Chapter 3.3.3.2 --- Models with CST Modification --- p.39 / Chapter 3.3.3.2.1 --- Model Using Correction Factors (Mod-2) --- p.39 / Chapter 3.3.3.2.2 --- Model Using Linear Equation (Mod-3) --- p.40 / Chapter 3.3.4 --- Evaluation - Me2P(S)C(OH)R1R2 --- p.41 / Chapter 3.4 --- Determination of Possible Conformation in Powder and Evaluation --- p.53 / Chapter 3.4.1 --- Introduction --- p.53 / Chapter 3.4.2 --- Methodology --- p.54 / Chapter 3.4.2.1 --- Preparation of Calibration Curve --- p.54 / Chapter 3.4.2.2 --- Determination of Possible Conformation Contributing to the Observed CST --- p.57 / Chapter 3.4.3 --- Evaluation --- p.59 / Chapter 3.5 --- Discussion --- p.72 / Chapter 3.5.1 --- Factors Affecting CST --- p.72 / Chapter 3.5.1.1 --- Inter-molecular Interaction --- p.72 / Chapter 3.5.1.1.1 --- O-H----S --- p.73 / Chapter 3.5.1.1.2 --- C-H----S --- p.78 / Chapter 3.5.1.1.3 --- van der Waals Forces --- p.80 / Chapter 3.5.1.2 --- Conformation --- p.81 / Chapter 3.5.2 --- Effect of Experimental Error on the Calculated Structure --- p.82 / Chapter 3.6 --- Summary --- p.84 / Chapter CHAPTER FOUR: --- APPLICATIONS --- p.86 / Chapter 4.1 --- Introduction --- p.86 / Chapter 4.2 --- Tetramethyldiphoshine Disulfide (TMPS) --- p.86 / Chapter 4.2.1 --- Local Structure --- p.87 / Chapter 4.2.2 --- Conformation --- p.92 / Chapter 4.3 --- "Carbon Compounds : 1,3,5-Trimethoxybenzene (1,3,5-TMB) and 1,4-Dimethoxybenzene (1,4-DMB)" --- p.97 / Chapter 4.3.1 --- Local Structure --- p.98 / Chapter 4.3.2 --- Conformation --- p.103 / Chapter 4.4 --- Conclusion --- p.110 / Chapter CHAPTER FIVE: --- CONCLUSIONS --- p.111 / APPENDIX --- p.114 / REFERENCES --- p.126

Hu Hong Bing. / "May 2004." / "13" in title is superscript. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Keung Yim Mei. / "October 2001." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 187-195). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

by Wang Guo-Xin. / "April 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 184-194). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

by Zhou ping. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (p. 160-170). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

Made available in DSpace on 2014-06-11T19:31:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-24Bitstream added on 2014-06-13T20:21:36Z : No. of bitstreams: 1 cruscajunior_e_dr_araiq.pdf: 3171142 bytes, checksum: b4f0f059cd560de4f1b2bd0af902bd16 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A existência de cepas resistentes aos antibióticos tradicionais aumenta a necessidade do desenvolvimento e estudo de novas drogas. Um grupo destas moléculas é o dos peptídeos antimicrobianos (PAMs). A ação dos PAMs é atribuída à formação de poros na membrana, aumentando sua permeabilidade e levando a morte celular. Somado aos estudos visando à elucidação dos mecanismos de ação dos PAMs, outros vêem sendo conduzidos para avaliar a importância de cada região da sequência em sua atividade biológica. Esta tese apresentou os estudos estruturais e biológicos de um peptídeo bioativo, proveniente da secreção cutânea da rã Hypsiboas albopuctatus, nomeado hilina a1 (Hy-a1) (IFGAILPLALGALKNLIK-NH2). O peptídeo hy-a1 é um peptídeo bioativo proveniente da secreção cutânea da rã Hypsiboas albopuctatus. Esta molécula mostrou atividade contra diversos tipos celulares, incluindo bactérias Gram-positivas, Gram-negativas, fungos, além de capacidade hemolítica. Este trabalho avaliamos a importância da carga e da estrutura da região N-terminal deste peptídeo. Para isto o peptídeo hy-a1, 4 análogos contendo o Trp substituindo a Leu na posição 6 e com modificações em sua extremidade N-terminal ([Trp6 ]hy-a1, Acetil-[Trp6 ]hy-a1, Lys-[Trp6 ]hy- a1 e Asp-[Trp6 ]hy-a1), e outros 2 análogos contendo alterações pontuais no meio da cadeia, foram manualmente sintetizados por meio da técnica de síntese de peptídeo em fase sólida. Os resultados obtidos demonstram que a síntese, por meio do protocolo Fmoc/tBu, utilizado na síntese dos peptídeos deste trabalho, foi viável. O processo de purificação dos materiais brutos obtidos por meio de HPLC também se mostrou eficiente e viabilizou a obtenção do material com índice de pureza superior a 95%. As atividades biológicas dos peptídeos obtidos foram determinadas por meio da análise da capacidade... / The presence of microorganisms that are resistant to conventional antibiotics, has led to the search of new drugs. One group of these molecules is the antimicrobial peptides (AMPs). The AMPs make the bacterial membrane permeable, which increases its permeability leading to cell death. Several studies towards the mechanism of action are being performed, as well as studies to analyze the importance of each region of the peptide sequence in its function. In this work, we present the structural and biological studies of a bioactive peptide, which was first isolated from the skin secretion of the frog Hypsiboas albopuctatus, named hylin a1 (Hy-a1) (IFGAILPLALGALKNLIK-NH2). The bioactive peptide hy-a1 has shown activity against several kind of microorganism, including Gram-positive and Gram-negative bacteria, fungus, moreover presents hemolytic activity. In the present work we evaluated the importance of the charge and the structure of the N-terminal region of this peptide. In this manner, the original peptide hy-a1, 4 analogues containing a Trp substituted for Leu at position 6 with modifications at the N-terminal ([Trp6 ]hy-a1, Acetil-[Trp6 ]hy-a1, Lys-[Trp6 ]hy-a1 and Asp- [Trp6 ]hy-a1), and 2 others analogues containing modifications in the middle of the chain, were manually synthesized by solid phase peptide synthesis. The results demonstrated that the Fmoc/tBu synthesis protocol was viable. The purification process of the crude peptides by HPLC also was efficient and allowed to obtain peptide. The biological activity of the peptides was assayed by the antibacterial, antifungical and hemolytic activities. The results demonstrated that: 1) the greater number of the peptides presented activity at a concentration of mmol/L, but with different minimal inhibitory concentration (MICs) for differ microorganism; 2) modifications on the N-terminus charge affect the activity... (Complete abstract click electronic access below)

Garantir a qualidade da carne bovina produzida no Brasil tem sido uma preocupação dos produtores, pois contribui para aumentar a exportação e o consumo interno do produto. Por isso, tem-se pesquisado novos métodos que analisam e garantam a qualidade da carne, de forma rápida, eficiente e não destrutiva. A ressonância magnética nuclear (RMN) tem se destacado como uma das técnicas de controle de qualidade de carne. Neste trabalho as redes neurais artificiais estão sendo utilizadas para o reconhecimento de padrões dos dados de ressonância magnética nuclear oriundos de carne bovina. Mais especificamente, os respectivos dados têm sido utilizados por uma rede perceptron multicamadas para a extração de características da carne bovina, possibilitando a classificação do grupo genético e do sexo dos animais a partir de uma amostra da referida carne. Os resultados dos experimentos são também apresentados para ilustrar o desempenho da abordagem proposta. / Guaranteeing the quality of the bovine meat produced in Brazil has been a concern of the producers because it contributes to increase the export and the domestic consumption of the product. Therefore, new methods have been researched that analyze and guarantee the quality of the meat in a fast, efficient and non destructive way. Nuclear magnetic resonance (NMR) has been highlighted as one of the techniques of meat quality control. In this work study artificial neural networks are being used for pattern recognition from data obtained by the resonance equipment, originating from bovine meat. More specifically, the respective data have been used by a multilayer perceptron network for extraction of bovine meat characteristics, making possible the classification of both genetic group and animal sex starting from a single meat sample. Several results of experimental tests are also presented to illustrate the performance of the proposed approach.

Neste trabalho é descrito o desenvolvimento de sistemas eletroquímicos (EQ) acoplados com a RMN de baixo e alto campo para análises in situ. Para a análise EQ-RMN de baixo campo, foi construído um sistema eletroquímico para ser utilizado tanto em um espectrômetro RMN-DT (B0= 0,23 T) quanto em um sensor unilateral (B0= 0,4 T). A platina foi utilizada como eletrodo de trabalho e contraeletrodo e um fio de prata como eletrodo de referência. A reação de eletrodeposição do cobre foi monitorada por meio do valor do tempo de relaxação transversal (T2), adquirido através da sequência de CPMG, em intervalos de 10 minutos durante a eletrólise, a potencial constante, no tempo de 3 horas. Ambas as análises, EQ-RMNDT e EQ-RMN Unilateral, apresentaram bom desempenho analítico. No entanto, foi observado que a análise de EQ-RMN Unilateral permitiu o monitoramento da reação eletroquímica com um volume detectável de amostra muito menor, em torno de 300 uL, do aquele para a RMN-DT (2,8 mL). O efeito do campo magnético (B0= 0,4 T) sobre o processo eletrolítico foi avaliado pela técnica de microscopia eletrônica de varredura (SEM). A análise SEM mostrou que o eletrodepósito de cobre obtido sob o efeito do campo apresenta uma morfologia rugosa. Para a análise in situ de EQRMN de alto campo, o sistema eletroquímico foi desenvolvido em um tubo de RMN de 10 mm de diâmetro, para ser utilizado em um espectrômetro de 9,4 T. A fibra de carbono foi o material mais adequado para ser utilizado como eletrodo de trabalho. A sequência de Precessão Livre no Estado Estacionário (SSFP, Steady State Free Precession), que não tem dependência do tempo de relaxação longitudinal T1, e permite a aquisição de centenas de espectros por segundo, foi utilizada para monitorar a eletrólise do 9-cloroantraceno por RMN de 13C. A célula EQ-RMN de alto campo construída possibilitou a aquisição de espectros de RMN de 1H e SSFP de 13C durante a eletrólise do 9-cloroantraceno. O Método da Diagonalizacão Filtrada (FDM, Filter Diagonalization Method) foi utilizado para processar sinais no domínio do tempo de SSFP 13C, para resolver os problemas de anomalia de fase e melhorar a resolução espectral. Os sistemas eletroquímicos construídos apresentaram um bom desempenho analítico para o interfaceamento com a RMN, e as metodologias empregadas propiciaram o monitoramento em tempo real de uma reação eletroquímica. / In this work it is described the development of electrochemical (EC) systems coupled to the Low and High-field NMR for in situ analysis. By low-field NMR-EC analysis, it was constructed an electrochemical system to be utilized both TD-NMR spectrometer (B0= 0.23 T) and unilateral sensor (B0= 0.4 T). Platinum was used as working electrode and counter electrode and a silver wire as reference electrode. The copper electrodeposition reaction was monitored by Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence. The measurements of the transverse relaxation time (T2) were collected in the interval of 10 minutes during electrolysis, constant potential, in 3 hours time. Both in situ analyses, TD-NMR-EC and Unilateral NMR-EC, demonstrated good analytical performance. However, the Unilateral NMR-EC allowed the monitoring copper concentration during electrolysis using detectable volume much smaller, approximately 300 uL, than TD-NMR (2.8 mL). The magnetic field effect (B0= 0.4 T) on electrolytic process was available by scanning electron microscopy (SEM) technique. The SEM analysis showed copper electrodeposits obtained on the field effect observes a rough morphology. For the in situ high-field NMR-EC analysis, the electrochemical system was developed in a tube NMR of 10 mm diameter to be utilized 9.4 T spectrometer. Carbon fiber was the most appropriated material to be used as working electrode. The Steady-state free precession (SSFP) sequence that has no dependence on the longitudinal relaxation time T1, allows it to acquire up to hundreds of spectra per T1 value, it was utilized to monitor the electrolysis of 9-chlroanthracene for 13C NMR. The high-field NMR-EC cell constructed allowed the acquisition of the 1H NMR and 13C SSFP spectra during the electrolysis of 9-chlroanthracene. The Filter Diagonalization Method (FDM) was used to process signals in the time domain of 13C SSFP, to solve problems of phase anomalies and improve the spectra resolution. The electrochemical systems constructed showed good analytical performance for coupling with NMR and the methodologies employed provided of the monitoring in real time of the electrochemical reaction.

O objetivo do presente estudo foi avaliar a efusão e o posicionamento do disco articular através de imagens por ressonância magnética nuclear (RMN) pré e pós-operatórios de duas técnicas de artrocentese da articulação temporomandibular. Foram incluídos 26 pacientes com deslocamento de o disco articular sem redução (DDSR), divididos aleatoriamente em dois grupos: artrocentese com 1 agulha com distensão do compartimento superior da ATM (A1) e artrocentese convencional com 2 agulhas (A2). Para comparação dos valores da efusão articular entre as intervenções nos diferentes momentos (antes e após um ano das artrocenteses), foi utilizado o teste qui-quadrado. Todas as análises foram realizadas com nível de significância de 5%. Em relação à efusão, após a realização dos tratamentos, foi observada uma diferença estatisticamente significativa entre as diferentes categorias de efusão (p=0,009), sendo essa diferença evidente no grupo de artrocentese convencional. Do total da amostra, apenas um caso não houve qualquer modificação do posicionamento do disco articular. Pode-se concluir que a artrocentese convencional foi capaz de alterar a variável efusão de maneira estatisticamente significativa, enquanto a artrocentese de agulha única e distensão do compartimento superior não. Ambas as técnicas foram responsáveis por alterar o posicionamento da cabeça mandibular, ou do complexo cabeça-disco, projetando-os nessa última situação para uma posição mais anterior o que pode ser verificado no exame de RMN final, com um aumento da distância interincisal máxima. O uso de artrocentese com emprego de uma única agulha é uma técnica mais simples, do que a artrocentese convencional o que possibilita um maior conforto para o paciente com menor tempo de procedimento e com resultados satisfatórios. / The aim of the present study was to evaluate the effusion and positioning of the articular disc through nuclear magnetic resonance imaging (NMRI) before and after two different arthrocentesis techniques for the temporomandibular joint. 26 patients with dislocation of the articular disc without reduction (ADDwoR) were included, and randomly divided into two groups: arthrocentesis using 1 needle with distention of the upper compartment of the TMJ (A1), and conventional arthrocentesis with 2 needles (A2). The chi-square test was used to compare the joint effusion values between the interventions at different moments (before and after one year of arthrocentesis). All analyzes were performed with a significance level of 5%. Regarding effusion, after the treatments, a statistically significant difference was observed between the different effusion categories (p = 0.009), which was evident in the conventional arthrocentesis group. Of the total sample, only one case did not have a modification of the position of the articular disc. It can be concluded that conventional arthrocentesis was able to change the effusion variable in a statistically significant way, whereas the single needle arthrocentesis and distention of the upper compartment did not. Both techniques were responsible for altering the position of the mandibular head, or the disc-head complex, projecting them in the latter situation, to a more anterior position with an increase in the maximum interincisal distance verified in the final NMRI examination. Arthrocentesis with a single needle is simpler than the conventional technique, for it allows greater comfort to the patient, a shorter procedure and satisfactory results.