Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Heterophasic ethylene-propylene copolymers, also known as impact polypropylene (PP) copolymers (IPCs) or heterophasic copolymers (HECOs), are a unique group of polyolefins produced through the copolymerisation of ethylene and propylene, with the aim of improving the impact properties of the PP homopolymer at low temperatures. Therefore, this polymer comprises of a PP homopolymer matrix with a dispersed rubbery copolymer phase. Due to their unique properties, HECO polymers have become commercially important materials, with a wide range of applications. Therefore a fundamental understanding of the processes and chemistry that affects their final macroscopic properties needs to be expanded. The main focus of this investigation was to understand why specific organic peroxides influence or interact differently with the various phases of HECO polymers, in order to utilize their properties to obtain HECO polymers with optimal and desired properties. Two HECO polymers with different ethylene contents were fractionated into three fractions (30, 100 and 130 °C), using preparative temperature rising elution fractionation (P-TREF). Each individual TREF fraction was degraded with two different types of organic peroxides, and then characterised using four different analytical tools. The changes in the molecular structures of the different fractions were investigated by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The changes in comonomer sequence distributions were investigated by carbon 13 nuclear magnetic resonance spectroscopy (13C-NMR). Moreover, the degradation of the different fractions was investigated by high temperature size exclusion chromatography (HT-SEC). The investigation showed that the HECO polymers with different ethylene contents were uniquely altered. It was evident that the ethylene content influenced the degradation behaviour of the HECO polymers. The ability of the peroxide to affect certain regions of the HECO polymer more than others is highly dependent upon its miscibility with certain regions of the HECO polymers. The “visbreaking” efficiency of a specific organic peroxide appears to be primarily dependent on the number of “peroxy” groups it contains in its molecular structure. Stellenbosch University https://scholar.sun.ac.za / AFRIKAANSE OPSOMMING: Heterofase etileen-propileen ko-polimere, ook bekend as impak PP ko-polimere (IPCS) of heterofase ko-polimere (HECO), is 'n unieke groep poliolefiene geproduseer deur die ko-polimerisasie van etileen en propileen, met die doel op die verbetering in die impak eienskappe van die PP homopolimeer by lae temperature. Hierdie polimeer bestaan dus uit 'n PP homopolimeer matriks met 'n verspreide rubberagtige ko-polimeer fase. As gevolg van hul unieke eienskappe, is HECO polimere van kommersiële belang, met 'n wye verskeidenheid van toepassings. 'n Fundamentele begrip van die prosesse en chemie wat die finale makroskopiese eienskappe beïnvloed moet dus uitgebrei word. Die hooffokus van hierdie ondersoek was om te verstaan waarom spesifieke organiese peroksiede verskillende invloede en interaksies met die verskillende fases van HECO polimere het, om sodoende van hul eienskappe gebruik te maak om HECO polimere te verkry met optimale en gewenste eienskappe. Twee HECO polimere met verskillende etileen inhoud was gefraksioneer in drie fraksies (30, 100 en 130 °C), met behulp van preparatiewe temperatuur styging eluering fraksionering (P-TREF). Elke individuele TREF fraksie was gedegradeer met twee verskillende tipes organiese peroksiede en daarna gekarakteriseer deur vier verskillende analitiese metodes. Die veranderinge in molekulêre strukture van die verskillende fraksies was geondersoek met behulp van Fourier transform infrarooi spektroskopie (FTIR) en differensiële skandering kalorimetrie (DSC). Die veranderinge in ko-monomeer volgorde distribusie was bestudeer deur middel van kern magnetiese resonans spektroskopie (KMR). Verder was die degradasie van die verskillende fraksies met behulp van hoë temperatuur grootte uitsluitingschromatografie (HT-SEC) bestudeer. Die ondersoek het getoon dat die HECO polimere met verskillende etileen inhoud uniek gedegradeer was. Dus is dit duidelik genoeg dat die etileen inhoud die degradasie gedrag van die HECO polimere beïnvloed het. Die vermoë van die peroksied om sekere areas van die HECO polimeer meer as ander te beïnvloed is hoogs afhanklik van die mengbaarheid met sekere areas van die HECO polimere. Die "visbreking" doeltreffendheid van 'n spesifieke organiese peroksiede is meestal afhanklik van die aantal "peroksie" groepe in die molekulêre struktuur.

This master's thesis discusses the use of UV/VIS spectrophotometry in chemistry teacher education. Optical methods principles are described in theoretical part of the thesis, and. the main part is dedicated to UV-VIS spectrophotometry. Tasks for quantifying and qualifying substances determination are described in experimental part. Educational tasks are described in a way so that chemistry teachers could use for instructions.

In this work we report the formation of inclusion complexes of the pesticides 1-naphthylacetic acid, 1-naphthylacetamide, napropamide and carbaryl with cucurbit[n]uril (n=7 and 8) and -cyclodextrin hosts. We also report results of the photochemistry of these compounds when free in aqueous solution and included within these nano-containers. The formation of inclusion complexes was studied by electrospray ionization mass spectrometry (ESI-MS) which gave us information about stoichiometry of the complexes and about their reactivity in the gas phase. The photodecomposition and formation of products was followed by high performance liquid chromatography coupled to both mass spectrometry (HPLC-MS) and UV/VIS detector, and spectrophotometry. The studied CBs and their host-guest complexes were readily detected in the gas phase by ESI-MS, mainly as single and double charged ions containing either H+ , Na+ or K+ . The assignments were made based on the m/z values of the observed signals and further confirmed by fragmentation (tandem mass spectrometry - MSn ). All pesticides formed 1:1 (host:guest) complexes. Carbaryl, napropamide and 1-naphthylacetamide also formed 1:2 (host:guest) complexes. Under some solution chemistry conditions, namely for concentrations of cucurbiturils above 50 µM and at low acid and...

Um sistema de análises químicas por injeção em fluxo foi desenvolvido e aplicado à determinação espectrofotométrica de baixas concentrações de sulfato em águas de chuva. O método explora a reação de deslocamento entre o ânion sulfato e o complexo dimetilsulfonazo (III) de bário, Ba-DMSA, com consequente formação do sal pouco solúvel BaSO4. A solução com o complexo Ba-DMSA apresenta alta absortividade molar a 656 nm, e uma diminuição pronunciada na absorbância ocorre na presença de sulfato. Desta forma, o sinal analítico é registrado como pico invertido proporcional à concentração de sulfato na amostra. A presença de altas concentrações de dimetilsulfóxido, DMSO, no reagente favorece a intensidade do sinal analítico, por coordenar as moléculas de água, melhorando a sensibilidade do método. A utilização do tensoativo dodecilsulfato de sódio, SDS, determina também uma melhoria considerável na sensibilidade analítica, pois sua presença no ambiente reacional altera as condições de supersaturação. A sensibilidade e seletividade do procedimento são melhoradas incluindo-se uma etapa de troca iônica em linha, com resina aniônica Dowex 1-X8, para concentração do sulfato e separação dos íons interferentes em potencial. O sistema proposto é robusto e fornece resultados precisos (d.p.r. < 0,01) com frequência analítica de 30 determinações por hora. O consumo de DMSA é de 0,17 \'mü\'mol por determinação. A curva analítica se apresenta linear até 2,0 mg L-1 SO42- e os limites de detecção e de quantificação foram estimados em 0,01 mg L-1 SO42- e 0,04 mg L-1 SO42-. / A flow injection system was developed and applied to the spectrophotometric determination of low concentrations of sulphate in rain waters. The method exploits the displacement reaction involving the sulphate anion and the barium dimethylsulfonazo (III) complex, Ba-DMSA, with consequent formation of the slightly soluble BaSO4 salt. As the Ba-DMSA solution is characterized by a high molar absorptivity at 656 nm, a pronounced absorbance lessening is observed in the presence of sulphate. The analytical signal is then recorded as an inverted peak proportional to the sulphate content in the sample. Presence of dimethylsulphoxide, DMSO, at high concentrations in the reaction medium leads to an enhancement of the analytical signals, coordinating water molecules, thus improving the sensitivity of the method. Addition of the surfactant sodium dodecylsulphate, SDS, results also in a pronounced improvement in sensitivity, as its presence in the reaction medium alters the supersaturation conditions. The sensitivity and selectivity of the method were improved by including an in-line ion exchange mini-column with the anionic resin Dowex 1-X8 into the manifold, for sulphate concentration and separation from potential interfering ions. The proposed system is robust and provides accurate results (R.S.D. <0.01) at an analytical frequency of 30 determinations per hour. About 0.17 \'mü\'mol DMSA are consumed per determination. The analytical curve is linear up to 2.0 mg L-1 SO42- and the detection and quantification limits were estimated as 0.01 mg L-1 SO42- and 0.04 mg L-1 SO42-.

Aus CdTe- und Edelmetallnanopartikeln werden 3-dimensionale Netzwerkstrukturen aufgebaut, welche durch einen überkritischen Trocknungsprozess zu hochporösen, weitverzweigten Halbleiter-Metall-Nanokompositen, sogenannten Aerogelen, umgewandelt werden. Zunächst werden Thiol-stabilisierte CdTe- und Edelmetallnanopartikel im wässrigen Milieu hergestellt und deren Morphologie und optischen Eigenschaften umfangreich mittels UV-Vis-Spektroskopie, Fluoreszenzspektroskopie und -lebensdauermessung, ICP-OES, TEM, STEM-EDX und AFM charakterisiert. Als Metallkomponente kamen Gold-, Palladium- sowie bimetallisch gemischte Gold-Palladium-Nanopartikel zum Einsatz. Die Gelierung der Nanopartikellösungen erfolgt durch Vermischen der Kolloide und anschließender kontrollierter Destabilisierung mithilfe einer Xe-Dampflampe oder der Zugabe von Wasserstoffperoxid. Neben einer mechanistischen Beschreibung der Gelbildungsmethoden wurden die resultierenden Hydrogele und die aus der überkritischen Trocknung erhaltenen Aerogele bezüglich Zusammensetzung, Morphologie und optischen Eigenschaften mithilfe von TEM und REM jeweils gekoppelt mit EDX-Analyse, Stickstoff-Porosimetrie, diffuser Reflexionsspektroskopie, Fluoreszenzspektroskopie und Fluoreszenzlebensdauermessungen untersucht. Weiterhin wird die UV-Vis-Spektroskopie als Methode zur Konzentrationsbestimmung von Gold in Lösungen kolloidaler Gold-Nanopartikel validiert. Dabei wird die Absorption der Kolloide bei einer Wellenlänge von 400 nm als Maß verwendet. Die NP-Lösungen werden anhand der Parameter Partikelgröße, Oberflächenfunktionalität und der Oxidationsstufe des enthaltenen Goldes variiert. / 3-dimensional network structures are formed combining CdTe and noble metal nanoparticles. A supercritical drying process allows production of highly porous and widely branched semiconductor-metal nanohybrids, so-called aerogels. Primarily, thiol-capped CdTe and noble metal nanoparticles are synthesized in aqueous media and their morphology and optical properties are studied extensively using UV-Vis and fluorescence spectroscopy, time-resolved fluorescence spectroscopy, ICP-OES, TEM, STEM-EDX and AFM. The metal entity involves gold and palladium nanoparticles as well as bimetallic mixed Au/Pd nanoparticles. After mixing of the different colloids gelation is induced by a controlled destabilization process using a Xenon lamp irradiation or the addition of hydrogen peroxide. Gelation techniques are described mechanistically. Resulting hydrogels and aerogels which are obtained by supercritical drying approach are characterized concerning composition, morphology and optical properties using TEM and SEM each coupled with EDX, nitrogen porosimetry, diffuse reflection spectroscopy, fluorescence spectroscopy and time-resolved fluorescence spectroscopy. Moreover, the UV-Vis spectroscopy is validated as a method to determine the gold concentration in gold nanoparticle solutions using the colloids absorbance at 400 nm as a measure. Gold nanoparticle solutions are varied concerning the parameters particle size, surface functionality and oxidation state of contained gold.

Contexte : Les troubles liés à l’usage des substances psychoactives constituent une priorité de santé publique dans le champ des pathologies chroniques. Les indicateurs de type Patient-Reported Outcomes (PRO) offrent des perspectives complémentaires aux indicateurs classiques pour la mesure de l’état de santé des patients et l’appréciation de la qualité des soins. Objectifs : Étudier les propriétés psychométriques de questionnaires de qualité de vie (QV) et les déterminants de la satisfaction précoce vis-à-vis des soins ambulatoires de patients dépendants aux substances de type alcool ou opiacés. Méthode : Les caractéristiques des patients et des médecins ont été recueillies à l’inclusion dans la cohorte SUBUSQOL. La satisfaction précoce a été mesurée quinze jours après la première consultation et ses déterminants ont été testés dans des modèles de régression linéaires multivariés. Les propriétés psychométriques du questionnaire spécifique Q-LES-Q-SF ont été étudiées au préalable sur un échantillon de patients. Résultats : La version française du Q-LES-Q-SF constitue un outil unidimensionnel robuste et fiable, les items du SF-12 et Q-LES-Q-SF présentent peu ou pas de fonctionnement différentiel selon l’âge, le sexe, le niveau d’éducation et le type d’addiction. Peu de variables recueillies sont associées à la satisfaction. Les patients dépendants à l’alcool se révèlent être plus satisfaits des modalités de contact et du délai de rendez-vous et ceux sans aucun antécédent de prise en charge pour leur dépendance plus satisfaits de leur consultation avec le médecin. Conclusion : Les questionnaires SF-12 et Q-LES-Q-SF peuvent être utilisés dans des populations de patients suivis en ambulatoire pour une dépendance aux substances psychoactives / Context: Of chronic diseases, substance use disorders are a public health priority. Patient-reported outcome indicators (PRO) offer additional insights into the classical indicators used to measure the patient’s health status and appreciation of their quality of care. Objectives: to study the psychometric properties of quality of life instruments and to study the determinants of early outpatient satisfaction with ambulatory care in alcohol- or opiate-dependent patients. Method: Patient and physician characteristics were collected in the SUBUSQOL cohort. Early satisfaction with care was measured fifteen days after the first consultation. The determinants of satisfaction were tested using multivariate linear models of regression. Prior data on the self-reported health status of a sample of alcohol- or opiate-dependent outpatients were used to investigate the psychometric properties of a specific questionnaire, the Q-LES-Q-SF. Results: Our results establish that the French version of the Q-LES-Q-SF is a unidimensional, valid and reliable instrument of self-reported health status assessment for use in care or medical research and that few items of the SF-12 and the Q-LES-Q-SF displayed differential functioning according to age, sex, educational level and type of substance use disorder. Our results show that few variables are associated with the level of patient satisfaction. Alcohol dependence was strongly associated with higher satisfaction with appointment making, and patients with no history of previous care for substance use disorders had a higher level of satisfaction with the doctor consultation. Conclusion: The use of the SF-12 and the Q-LES-Q-SF is recommended for outpatients suffering from substance use disorders

Um aspecto importante relacionado à operação de sistemas de distribuição é o referente à segurança nas ações de restabelecimento pós-perturbações, em manobras emergenciais e programadas, onde necessite de transferência de cargas entre alimentadores aéreos primários de uma mesma subestação ou para uma subestação adjacente, de forma segura e confiável. Devem-se observar os requisitos de carregamento, tensão a nível sistêmico, proteção, entre outros. Atualmente as decisões e tomadas de ações referentes às manobras necessárias para os remanejamentos de cargas são de competência dos operadores que atuam nas salas de controle de operações e, em muitos casos, respaldadas somente na experiência de cada operador, acumulada ao longo do tempo. Este trabalho visa o estudo dos fenômenos físicos envolvidos em situações que coloquem alimentadores aéreos primários de distribuição em paralelo ou mesmo quando se forme uma configuração em anel fechado. Estas manobras podem ser executadas através de alimentadores e transformadores distintos, de mesma potência ou de potências diferentes, estabelecendo diretrizes e respaldando os operadores das salas de controle em situações de emergência, urgência ou programadas no sistema aéreo de distribuição. O objetivo principal é oferecer informações técnicas, possibilitando as tomadas de decisões mais adequadas na coordenação de manobras no sistema aéreo de distribuição, em tempo real. Cada uma delas tem condições que se pode considerar como a mais adequada para a execução dos procedimentos estabelecidos, porém sem os principais subsídios técnicos. Desta forma, algumas variáveis como tensão mínima, limites de carregamento de equipamentos, ângulo de fase dos transformadores, restrições operativas do sistema e de consumidores, devem ser aplicadas em tempo real para a tomada de decisão por parte dos operadores do sistema elétrico. / An important aspect related to the distribution systems operation concerns the safety required in the post-disturbances restorement actions or in the emergency and scheduled maneuvers, which involve the need for load transfer between primary overhead feeders of a same sub-station or for an adjacent sub-station, in a safe and reliable way, complying with the loading requirements, voltage at systemic level and protection, among others. Currently the decisions and taking actions related to the necessary maneuvers to carry out the load transfers are responsibility of the operators who work in the operations control rooms, and in many cases, only endorsed by each operator´s own experience, gathered along the time. This paper aims at the study of the involved physical phenomena in situations that place distribution primary overhead feeders in parallel or even when a configuration in closed ring is formed, via distinct transformers and feeders of same or different powers, establishing guidelines and endorsing the control rooms operators in emergency, urgency or scheduled situations in the distribution overhead system. The main objective is to provide technical information, enabling more adequate taking decisions in the distribution overhead system maneuvers coordination, in real time. Each of them has conditions that can be considered the most adequate to carry out the established procedures, however without the main technical information. Thus, some variables such as minimum voltage, equipment loading limits, transformers´ phase angle, the operational restrictions of the system and customers must be applied in real time for the taking decision by the electrical system operators.

O trabalho teve o objetivo de investigar técnicas de sensoriamento de solo e analisar o potencial de utilização das mesmas diretamente no campo. Quatro etapas distintas foram desenvolvidas para atender aos seguintes objetivos: a) comparar e avaliar o potencial de predição de atributos do solo de três espectrômetros portáteis (vis-NIR) em ambiente controlado; b) avaliar a predição em movimento de pH, P e K utilizando técnicas de sensoriamento óptico (reflectância vis-NIR) e eletroquímico (eletrodos íon-seletivos de pH e K) em uma área experimental com variabilidade induzida; c) montar e testar uma plataforma de campo com sensores elétricos, eletroquímicos e ópticos; d) avaliar o potencial de predição de textura do solo utilizando um equipamento portátil de espectroscopia de fluorescência de raios X. Na primeira etapa as leituras de reflectância espectral vis-NIR dos três equipamentos avaliados mostraram-se muito semelhantes, com coeficientes de correlação acima de 0,86 na faixa de 400 a 1800 nm. Quando comparados nesta região espectral os equipamentos produziram modelos de predição muito semelhantes, com leve superioridade para o sistema FieldSpec. Os modelos mostraram-se mais promissores para a predição da textura do solo em relação aos atributos químicos. Na segunda etapa as leituras de campo utilizando eletrodos íon-seletivos de pH e K apresentaram uma alta correlação com as análises de laboratório. As avaliações permitiram observar que condições de solo com baixa umidade prejudicam sensivelmente as leituras. Apesar da alta correlação, os valores de campo precisam ser corrigidos para a metodologia de laboratório desejada. Os modelos de predição de P, K e pH utilizando espectrometria vis-NIR no campo apresentaram baixa precisão. Os testes da Plataforma Multisensores de Solo (PMS) na terceira etapa demonstraram ser possível a utilização de sensores elétricos, eletroquímicos e ópticos em uma mesma plataforma. As leituras de condutividade elétrica aparente do solo (CEa) demonstraram que este parâmetro está relacionado com a textura, atuando como um indicador da variabilidade e possibilitando a identificação dos locais de transição de textura. O pH mensurado pela PMS exibiu correlações abaixo das verificadas na segunda etapa. No entanto, alguns resultados atípicos foram verificados, como a correlação maior entre pH em CaCl2 com a PMS do que em relação ao método em H2O. As leituras de reflectância vis-NIR utilizando a PMS apresentaram bons modelos de predição de areia e argila, permitindo a criação de mapas de alta resolução destes parâmetros. A espectroscopia de fluorescência de raios X portátil foi eficiente para estimar a textura do solo. Os teores de areia e argila foram estimados tanto por meio de regressões lineares simples como regressões múltiplas com valores de R2 acima de 0,60. O Fe total foi o principal elemento utilizado nesses modelos de regressão. / The objective of this work was to investigate soil sensing techniques and to analyze the potential for their use directly in the field. Four distinct steps were developed to meet the following objectives: a) to compare and evaluate the potential of predicting soil attributes with three portable spectrometers (vis-NIR) in a controlled environment; B) to evaluate the on-the-go prediction of pH, P and K using optical sensors (vis-NIR reflectance) and electrochemical techniques (ion-selective pH and K electrodes) in an experimental area with induced variability; C) assemble and test a field platform with electrical, electrochemical and optical sensors; D) to evaluate the potential of predicting soil texture using a portable X-ray fluorescence spectroscopy equipment. In the first step the vis-NIR spectral reflectance readings of the three equipments evaluated were very similar, with correlation coefficients above 0.86 in the 400 to 1800 nm range. When compared in this spectral region, the equipment produced very similar prediction models, with slight superiority for the FieldSpec system. The models showed to be more promising for the prediction of soil texture in relation to chemical attributes. In the second step the field readings using ion-selective pH and K electrodes presented a high correlation with the laboratory analyzes. The evaluations showed that soil conditions with low moisture significantly affect the readings. Despite the high correlation, the field values need to be corrected for the desired laboratory methodology. Prediction models of P, K and pH using field-vis-NIR spectrometry showed low precision. The tests of the Multisensors Soil Platform (MSP) in the third stage demonstrated that it is possible to use electric, electrochemical and optical sensors in the same platform. The electrical conductivity (EC) readings showed that this parameter was related with soil texture, acting as an indicator of variability and allowing the identification of texture transitions. The pH measured by MSP exhibited correlations below those verified in the second step. However, some atypical results were verified, such as the higher correlation between pH in CaCl2 and MSP than in H2O. The vis-NIR reflectance readings using the MSP resulted in good sand and clay prediction models, allowing the creation of high resolution maps of these parameters. Portable X-ray fluorescence spectroscopy was efficient for estimating soil texture. The sand and clay contents were estimated both by simple linear regressions and multiple regressions with R2 values above 0.60. Total Fe was the main element used in these regression models.

Made available in DSpace on 2017-07-21T18:53:07Z (GMT). No. of bitstreams: 1 Janio Santos.pdf: 2918457 bytes, checksum: 102357b433cd6ca1bff688e4810640bc (MD5) Previous issue date: 2016-07-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Rooibos (Aspalathus linearis) is a leguminous shrub of African origin, which attention has been dedicated to its most important technological product: Aqueous extract (tea).Rooibos tea has a complex chemical composition with various quantities phenolic compoundsin addition to high levels of aspalathin, a dihydrochalcone found only in rooibos. Therefore, the objective of this study is to evaluate the effects of time and temperature of extraction the phenolic compounds and functional in vitro properties of aqueous extracts of fermented organic Aspalathus linearis. Initially been prepared by an aqueous 22 extracts seven experiment design red rooibos for evaluation of the linear and combined effects of temperature and extraction time. By means of spectrophotometric methods primarily extracts were evaluated for the effect of time and temperature of extraction the content of phenolic compounds, flavonoids, flavonols, hydrolyzable condensed tannins and ortho-phenolic antioxidant activity against the DPPH and ABTS radical, reducing capability iron and reducing total capacity. Posteriorly it was performed for identification and quantification phenolic compounds 19 by high-performance liquid chromatography. The third step was to evaluate the inhibitory activity of α-amylase and α-glucosidase in vitro and hemolytic profile of aqueous extracts of rooibos red in human erythrocytes. The principal component analysis (PCA) was used to associate the chemical composition, antioxidant activity, reducing capacity, and inhibition of enzymes (α-amylase and α-glucosidase). In a general way the extract that was subjected to the extraction process in the higher temperature of the design (85 °C) showed the highest levels of total phenolics, flavonoids, flavonols, hydrolyzable condensed tannins and ortho-phenolic and antioxidant activity against the DPPH and ABTS, as the reducing capacity of iron and reducing total capacity, with little influence of time.The antioxidant activity and reducing capacity of rooibos extracts were shown to be correlated with the content of phenolic compounds, flavonoids, flavonols and ortho-diphenols. The quercetin contents, isoquercitrin, and rutin and were correlated with ABTS, DPPH, FRAP and total capacity reduction.Thus, we can say that such compounds are in vitro directly linked functionality presented by the aqueous extract of rooibos. In relation the antimicrobial activity of the extracts at concentrations from 7.81 to 1000 mg L-1 were not been effective in inhibiting the growth of tested microorganisms.As regards the inhibitory activity of α-amylase and α-glucosidase in general, all analyzed samples showed similar values extract to inhibit 50% of enzyme activity (IC50).The tea extract at 80 °C for 10 min was used for hemolysis test in which it was observed that there was beneficial interaction with the erythrocytes, reducing the occurrence of erythrocyte hemolysis in the cell.Is possible to observe a decrease in haemolytic activity with increased concentration of rooibos extract, this characteristic indicates that inhibition of plasma hemoglobin release is dependent on the concentration of rooibos extract contained in the medium. However, overall, the extraction temperature is the mainpositive factor that influences these variables in organic red rooibos. / Rooibos (Aspalathus linearis) é um arbusto leguminoso de origem africana, cuja atenção tem sido voltada ao seu produtotecnológico mais importante: Extrato aquoso (chá).O chá de rooibos apresenta uma composição química complexa com quantidades de vários compostos fenólicos, além de níveis elevados de aspalatina, uma dihidrocalcona encontrada apenas em rooibos. De tal modo o objetivo do presente estudo foi avaliar os efeitos do tempo e temperatura na extração dos compostos fenólicos e propriedades funcionais in vitro de extratos aquosos de Aspalathus linearis orgânicofermentado. Inicialmente foram preparados por meio de um delineamento de experimento 22 sete extratos aquosos de rooibos vermelho para avaliação dos efeitos lineares e combinados da temperatura e tempo de extração. Por meio de métodos espectrofotométricos primeiramente os extratos foram avaliados quanto ao efeito do tempo e da temperatura de extração no teor de compostos fenólicos totais, flavonoides, flavonóis, taninos condensados hidrolisáveis e orto-difenólicos, atividade antioxidante frente aos radicais DPPH e ABTS, capacidade redutora do ferro e capacidade redutora total. Posteriormente à identificação e quantificação de 19 compostos fenólicos foram realizadas por meio de cromatografia liquida de alta eficiência acoplada à espectrometria de massas (LC-ESI-MS/MS). O terceiro passo foi avaliar atividade inibitória das enzimas α-amilase e α-glucosidasein vitro e o perfil hemolítico dos extratos aquosos de rooibos vermelho em eritrócitos humanos. A análise de componentes principais (PCA) foi usada para associar a composição química, atividade antioxidante, capacidade redutora, e inibição das enzimas (α-amilase e α-glucosidase). De modo geral o extrato que foi submetido ao processo de extração na maior temperatura do delineamento (85 °C) apresentou os maiores teores de compostos fenólicos totais, flavonoidestotai, flavonóis totais, taninos condensados hidrolisáveis e orto-difenólicose na atividade antioxidante frente aos radicais DPPH e ABTS, como na capacidade redutora do ferro e capacidade redutora total, com pouca influência do tempo. A atividade antioxidante e capacidade redutora dos extratos de rooibos mostraram-se correlacionadas com o teor de compostos fenólicos totais, flavonoides, flavonóis e orto-difenólicos.Os teores de quercetina, isoquercitrina, e rutina e foram correlacionados com ABTS, FRAP e capacidade redutora total. Assim, é possível afirmar que tais compostos quantificados estão diretamente ligados às funcionalidades in vitro apresentadas pelo extrato aquoso de rooibos. Em relação a atividade antimicrobiana, os extratos nas concentrações de 7,81 a 1000 µg mL-1 não foram eficazes em inibir o crescimento dos micro-organismos testados.No que diz respeito à atividade inibitória das enzimas α-amilase e α-glucosidase, todas as amostras analisadas mostraram valores similares de extrato para inibir 50% da atividade enzimática (CI50). O chá extraído a 80°C por 10 min foi usado para o teste de hemólise no qual foi constatado que ocorreu uma interação benéfica com os eritrócitos, diminuindo a ocorrência de hemólise nas células eritrocitárias. Observa-se uma diminuição da atividade hemolítica com o aumento da concentração do extrato de rooibos, tal característica aponta que a inibição da liberação de hemoglobina no plasma é dependente da concentração de extrato de rooibos contido no meio. Conclui-se de modo global, que a temperatura de extração é o fator de maior influência positiva nessas variáveis em rooibos fermentado orgânico.

Made available in DSpace on 2017-07-21T18:53:11Z (GMT). No. of bitstreams: 1 dissertacao parcial.pdf: 389132 bytes, checksum: 1072407aabab8f91b6ea13999acc01d4 (MD5) Previous issue date: 2009-02-06 / Pectinases, a group of enzymes that degrade pectic substances and break glycosidic linkages, are produced by fungi, yeasts and bacteria, but are also in plants in general and fruit in particular.In the juice industry the pectinolytic enzymes are added to increase the efficiency of the process, decrease the viscosity and reduce the time of filtration. The pectin methylesterase, PME, hydrolyzes the methyl ester groups, forming carboxyl groups in pectin chain, releasing methanol end H3O+. Therefore, its knowledge is vital in order to control the effectiveness of the treatment. The purpose of this study was to determine the optimum conditions of the activity of the pectin methylesterase in industry preparations, proposing a potentiometric procedure for determining the PME activity and compare the data with those obtained by traditional potentiometry and Uv-Vis, evaluate the efficacy of this method in determining the residual activity exogenous of PME in mango juice. The activity of PME in the three commercial samples, Pectinex 100L Plus, Panzym Univers and Panzym Clears, was determined by potentiometry, Uv-Vis spectroscopy, with the bromophenol blue indicator, and the action of alcohol oxidase with acetyl acetone. The reaction consisted of 5.00 mg.mL-1 apple pectin, 0.100 mol.L-1 sodium chloride and 50 μL commercial pectinolytic enzyme for a volume of 30 mL. In all experiments the enzyme deesterification showed first-order kinetics, with increased activity at pH 4.0 to 4.5 and 45 ºC, whereas the complete inactivation occurred at 75 ºC for 10 minutes, in the three industrial preparations. The thermal inactivation of the PME of Pectinex 100L Plus and Panzym Clears preparations occurred under the same conditions, when the activity was measured by the procedures of ΔVNaOH / Δttime or of ΔpH/ Δttime. The activity of PME in industrial preparations at 25 °C and pH 4.5, determined by UV-Vis spectroscopy with bromophenol blue indicator, showed good correlation with the activity determined by the procedures by potentiometry. The stability of the indicator in the pectin solution allows its use to determine the PME activity in samples in which the optimum pH is located in acid band. The release of methanol as measured by alcohol oxidase, followed by the reaction with acetyl acetone to determine the formaldehyde, showed good agreement with the results of the enzyme activity measuring procedures used in this research. The inactivation of residual PME in mango juice occurred at 75 ºC for 20 minutes of exposure in the procedure ΔVNaOH / Δttime and 10 minutes of exposure during the procedure ΔpH/ Δttime. The residual activity of PME in 70 °C for 10, 20 and 30 minutes of exposure in the presence of juice was higher than in the control, indicating its protective effect. The procedure of ΔpH/ Δttime shows good correlation with other methods, with the advantage of precise and direct measures of [H+], excusing a series of reagents and high costs materials. / As pectinases, um grupo de enzimas que degradam substâncias pécticas e rompem ligações glicosídicas, são produzidas por fungos filamentosos, leveduras e bactérias, mas encontram-se também em plantas em geral e em frutas, em particular. Na indústria de sucos as enzimas pectinolíticas são adicionadas para aumentar o rendimento do processo, diminuir a viscosidade e reduzir o tempo de filtração. A pectina metilesterase, PME, hidrolisa os grupos metil éster, formando grupos carboxilícos na cadeia da pectina, produzindo metanol e H3O+.Portanto, é fundamental o seu conhecimento, a fim de controlar a eficiência do tratamento. O objetivo deste trabalho foi determinar as condições ótimas da atividade da PME presente em preparações industriais, propor um procedimento potenciométrico para determinação da atividade da enzima e comparar os dados com os obtidos por potenciometria tradicional e Uv- Vis, avaliar a eficiência do método proposto na determinação da atividade residual da PME exógena no suco de manga. A atividade da PME nas três amostras comerciais, Pectinex 100L Plus, Panzym Univers e Panzym Clears, foi determinada por potenciometria, espectroscopia Uv-Vis, com o indicador azul de bromofenol, e pela ação do álcool oxidase com acetil acetona. A reação consistiu de 5,00 mg.mL-1 de pectina de maçã, 0,100 mol.L-1 de cloreto de sódio e 50 μL de enzima pectinolítica comercial para um volume de 30 mL. Em todos os experimentos a desmetoxilação enzimática mostrou uma cinética de primeira ordem, com maior atividade em pH 4,0 a 4,5 e 45 ºC, sendo que a inativação completa ocorreu a 75 ºC por 10 min, nas três preparações industriais. A inativação térmica da PME das preparações Pectinex 100L Plus e da Panzym Clears ocorreu sob mesmas condições, quando a atividade foi medida pelos procedimenos de ΔVNaOH / Δttempo ou de ΔpH/ Δttempo. A atividade da PME nas preparações industriais a 25 ºC e pH 4,5, determinada por espectroscopia Uv-Vis com o indicador azul de bromofenol, apresentou boa correlação com a atividade determinada pelos procedimentos por potenciometria. A estabilidade do indicador em solução com a pectina permite a sua utilização para determinar a atividade da PME em amostras nas quais o pH ótimo localiza-se na faixa ácida. A liberação do metanol medida pela álcool oxidase, seguida da reação com a acetil acetona para determinar o formaldeído, mostrou boa concordância com os resultados dos procedimentos de medida de atividade enzimática utilizados neste trabalho. A inativação da PME residual em suco de manga ocorreu na temperatura de 75 ºC por 20 min de exposição no procedimento ΔVNaOH / Δttempo e durante 10 min de exposição pelo procedimento ΔpH/ Δttempo. A atividade residual da PME a 70 ºC por 10, 20 e 30 min de exposição em presença do suco foi maior do que no controle, indicando o seu efeito protetor. O procedimento da ΔpH/ Δttempo apresenta boa correlação com os demais métodos, com a vantagem de medidas precisas e diretas da [H+], dispensando uma série de reagentes e materiais de custos elevados.