No description available.

<p>Razvoj savremenih sistema za ciljanu aplikaciju farmakolo&scaron;ki aktivne supstance zasniva se na postojanju interakcija između funkcionalnih grupa makromolekula i povr&scaron;inski aktivne materije &scaron;to omogućava kontrolisano oslobađanje, smanjenu toksičnost i bolji režim doziranja leka. Prisustvo tenzida, kako se jos povr&scaron;inski aktivne materije nazivaju, u niskim koncentracijima može značajno da izmeni konformaciju makromolekula i viskozitet sistema, i samim tim pro&scaron;iri mogućnosti primene modifikovanjem svojstava. Stoga je poznavanje fizičko-hemijskih osobina vodenih rastvora makromolekul-povr&scaron;inski aktivna materija neophodno radi dobijanja adekvatnog finalnog proizvoda unapređenih osobina uz primenu optimalnih koncentracija pomoćnih supstanci. U radu su prikazani rezultati ispitivanja uticaja natrijum lauril sulfata, predstavnika anjonskih tenzida, odnosno polioksietilen (20) sorbitan monooleata, kao &scaron;iroko kori&scaron;ćenog nejonskog tenzida na fizičko-hemijske osobine vodenih rastvora makromolekula karbomera 940 i ksantan gume. U cilju potpunog razumevanja ovih sistema, čiste komponente su prvo analizirane infracrvenom spektroskopijom primenom Fourierove tranformacije. Pona&scaron;anje karbomera 940 odnosno ksantan gume u prisustvu tenzida, ispitano je kombinacijom različitih tehnika (viskozimetrije, konduktometrije, tenziometrije, spektroskopije, spektrofluorimetrije, skenirajuće elektronske mikroskopije) koje pružaju uporedive rezultate. Određene vrednosti interakcionih parametara, potvrdjuju hipotezu o postojanju međudejstva između karbomera 940/ksantan gume i ispitivanih tenzida i ukazuju da povećanje koncentracije makromolekula u rastvoru uslovljava &scaron;irenje opsega interakcije. Tenzidom indukovane promene konformacije ksantan gume odnosno karbomera 940 potvrđene su i na mikroskopskom nivou. Takođe, rezultati uticaja ispitivanih tenzida na osobine vodenih rastvora sme&scaron;a karbomera 940 i ksantan gume dobijeni su istim tehnikama. Međudejstvom dva različita polimera bez dodatne sinteze na jeftin i brz način mogu se postići željene karakteristike sistema. Na osnovu eksperimentalnih rezultata definisani su matematički modeli primenom metodologije odzivnih povr&scaron;ina i vi&scaron;estruke linearne regresije, čija je validnost statistički potvrđena te se mogu primeniti u optimizaciji i predviđanju fizičko-hemijskih osobina vodenih rastvora analiziranih binarnih sistema.</p> / <p>The possible interactions between polymers and surfactants are of great interest in the development of drug delivery systems, where they improve therapeutic efficiency by the controlled release and reduced toxicity. The addition of even a small amount of surfactant could change the physico-chemical properties of polymer dispersions in terms of viscosity and stability of the system and, consequently, enlarge possibilities for their application. Therefore, understanding the physico-chemical properties of polymer-surfactant aqueous solutions are necessary in order to optimize the formulation of these compounds and consequently to get product with acceptable properties and desired effect. In this thesis the physico-chemical changes of carbomer 940 and xanthan gum influenced by different surfactants were investigated. Widely used anionic surfactant sodium dodecyl sulfate, and nonionic polyoxyethylene (20) sorbitan monooleate were used. In order to completely understand the mechanism of interaction the pure polymers and surfactants were tested by Fourier transform infrared spectrometer. The behaviour of carbomer 940 as well as xanthan gum in the presence of examined surfactants were analysed by the combination of different techniques such as viscometry, conductometry, tensiometry, spectrophotometry, fluorimetry and scanning electron microscopy. The obtained results confirmed the existence of interactions between carbomer 940 / xanthan gum and tested surfactants. Furthermore, the interaction parameters were determined and the polymer saturation points for both surfactants increased with the increase in carbomer 940 and xanthan gum content, respectively. Additionally, the surfactant induced microstructural changes of carbomer 940 as well as xanthan gum were confirmed. Moreover, the physico-chemical properties of the mixture of carbomer 940 and xanthan gum influenced by the addition of anionic and nonionic surfactant were examined by the same techniques. Without additional synthesis the desired characteristics of the system could be achieved by optimizing the interaction between two different polymers. The obtained results were analysed by response surface methodology and multiple linear regression analysis. The defined mathematical models could be used to optimize and predict physico-chemical properties of aqueous solutions of the tested binary systems.</p>

Dissociation of gas hydrates has been the primary concern of the oil and gas industry for flow assurance, mainly in an offshore environment. There is also a growing interest in the rapid formation of gas hydrates for gas storage, transport of natural gas and carbon sequestration. In this thesis, we experimentally measure the kinetics of formation and dissociation of methane hydrates and the effect of various anionic and cationic surfactants such as sodium dodecyl sulfate (SDS), cetyl trimethylammonium bromide (CTAB) and alpha olefin sulfonate (AOS) on the association/dissociation rate constants. The importance and necessity of micelle formation in these surfactants has been studied. The effect of foam generation on the rate of formation of these hydrates has also been measured. SDS was found to significantly decrease the induction time for hydrate formation. There was an added decrease in the induction time when a foamed mixture of water and SDS was used. On the other hand CTAB and AOS had an inhibiting effect. The contribution of micelles towards promoting hydrate formation was demonstrated with a series of experiments using SDS. The micelles formed by these surfactants appear to serve as nucleation sites for the association of hydrates. New experimental data is presented to show that some surfactants and the use of foam can significantly increase the rate of hydrate formation. Other surfactants are shown to act as inhibitors. A new experimental setup is presented that allows us to distinguish between surfactants that act as promoters and inhibitors for hydrate formation. / text

Gas hydrate formation generally involves gas dissolution, formation of nuclei and growth of new nucleus. On condition of synthesizing experiments without agitation, the formation of hydrate nuclei is comparatively difficult and needs an induction period which is considerably uncertain and random. Some additives such as surfactant sodium dodecyl sulfate (SDS) can increase the formation rate and reduce the induction time. A hydrate formation and mini drilling experimental system was used to carry on methane hydrate formation experiments with small quantity of SDS and SDS- tetrahydrofuran(THF) in deionized water. The reactor is a high pressure cell (40Mpa) made of titanium alloy with 4 transparent windows and an inner volume of about 2.8 liters. The effect of SDS and THF hydrate on the formation rate and amount of methane hydrate was studied by comparative testing and analyzing the collected data of temperature and pressure. According to the results of the tests, the formation rate of methane hydrate in the SDS-THF solution was faster than that in the SDS solution. As a water-soluble hydrate former, THF hydrate nucleation may be benefit of methane hydrate nucleation. A small amount of SDS and THF could dramatically promote the formation of methane hydrate in the pure water, and rapidly increase the amount of methane hydrate too. Therefore, a great deal of time for experiment was saved, which established a good basis for the coming mini drilling and drilling fluid experiments.

Warfarin is a well-known anticoagulant drug that is used to prevent cardiovascular disease and blood coagulation such as thrombosis. In this study, the main aim was to investigate the photo physical characteristics of warfarin in the different molecular environments provided by sodium dodecyl sulfate (SDS) micelles by using ultraviolet absorption and fluorescence emission spectroscopic techniques. Warfarin and a structural analogue not existing in solution as a cyclic hemiketal, phenprocoumon, were mixed with different concentrations of SDS and spectral changes for these warfarin and phenprocoumon were recorded. Interestingly, results demonstrated, based on an evident increase in the absorption intensity at 273 nm and an evident blue shift in the fluorescence emission spectrum after the addition of an increasing concentration of SDS, that primarily the cyclic hemiketal isomer of warfarin was found to be solvated by SDS micelles at an apparent recorded critical micelle concentration of ~8mM.  Altogether these observations suggest that warfarin may be used as a molecular probe to explore the polarities of complex colloidal mixtures. Moreover, the possibility of using micelles for controlling the isomeric state of warfarin is interesting and can potentially be used for better controlling dosage of warfarin thereby reducing side effects.

Master of Science / Department of Biological and Agricultural Engineering / Donghai Wang / Algae proteins have similar amino acid compositions as conventional plant proteins, and are comparatively richer in the essential amino acids. Algae protein has the potential to be used in the development of a wide variety of products, including foods, animal feeds, bioplastics, and adhesives. The utilization of algae protein for value-added products would increase the economic feasibility of algae biodiesel. This research evaluated the adhesion, rheological, morphological, and thermal properties of adhesives made from algae protein extracted from Cladophora sp. and modified with either sodium hydroxide (pH 9, 10, 11) or sodium dodecyl sulfate (SDS, 0.5, 1, and 3%). Both alkali-modified and SDS-modified algae protein adhesives displayed improved dry shear strength compared to unmodified algae protein. However, only 3% SDS-modified algae protein significantly improved the water resistance as shown in wet and soak shear strength tests. Thermal analysis using differential scanning calorimetry showed that SDS modification caused complete denaturation of the algae protein. SDS modification also increased the viscosity of the adhesive and created rougher particle surface texture. These data suggest that SDS modification can effectively increase shear strength and water resistance of algae protein adhesives caused by protein denaturation and protein structure change.

High-Gradient Magnetic Separation (HGMS) is a powerful separation process that has great potential for industrial wastewater treatment, particularly for the removal and recovery of paramagnetic colloidal particles. The chief advantages of HGMS are that the separation is reversible and potentially selective. However, these advantages are compromised if non-magnetic filtration mechanisms influence significantly the capture of particles. The objective of this study was to identify the chief mechanisms responsible for the removal of ferric oxide (Fe2O3) from water by an HGMS process. This objective was achieved by measuring the effects of applied magnetic induction, collector radius, and fluid velocity on the removal efficiency (RE) of a stainless-steel filter column. These factors were tested on the removal of bare Fe2O3 particles and particles treated with a surfactant (sodium dodecyl sulfate, SDS). The results were compared to the predictions of a trajectory model which simulates particle capture by a magnetic force. The experimental results show that non-magnetic force mechanisms are primarily responsible for the removal of bare Fe2O3 particles for the experimental conditions used in this work. For these particles, the three factors tested had no significant effect on the RE, and 90.1% of the particles were removed without a magnetic force. These results differed sharply from modeling predictions. However, the magnetic force mechanism is primarily responsible for the removal of surfactant-treated Fe2O3 particles. The three factors investigated had a marked effect on the RE, and only 10.8% of the particles were removed without a magnetic force. An increase in magnetic induction from 0.2 to 0.5 T increased the RE from 79.9 to 93.4 %; a decrease in wire radius from 49 to 15 Ym increased the RE from 60.2 to 93.4%, and a decrease in fluid velocity from 0.5 to 0.1 cm/s increased the RE from 69.5 to 95.3%. These results agreed closely with the model predictions.This study demonstrates that by reducing the effect of attractive non-magnetic forces on filtration, surfactant treatment of colloidal particles can potentially preserve and enhance these two key advantages, i.e., regeneration and selectivity of HGMS processes.

Made available in DSpace on 2014-06-11T19:32:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-12-18Bitstream added on 2014-06-13T19:42:27Z : No. of bitstreams: 1 correia_cm_dr_araca.pdf: 275887 bytes, checksum: 756fbfef30ea96ed1ecb1864b78586b4 (MD5) / Os tratamentos utilizados para a prevenção da xerostomia não atingem a eficácia esperada pelos pacientes, podendo ainda produzir efeitos colaterais indesejáveis. O objetivo deste trabalho foi avaliar quantitativamente o índice de fluxo salivar total não estimulado de pacientes portadores de câncer de cabeça e pescoço durante e após tratamento radioterápico exclusivo tratados com a associação de laurildietileno- glicol-éter-sulfato de sódio e hidróxido de cálcio (HcT20). Este estudo foi realizado no Hospital Dr. Hélio Angotti envolvendo trinta e um pacientes (n=31) divididos em dois grupos: o grupo I composto por dezessete pacientes (n=17) submetidos à telecobaltoterapia, na dose total de 7.000 cGy e receberam o HcT20 durante o tratamento. O grupo II composto por quatorze pacientes (n=14) iniciaram o uso do HcT20 após a conclusão da radioterapia. Foram realizadas e mensuradas coletas semanais do índice de fluxo salivar total não estimulado para os pacientes dos dois grupos. Os valores obtidos foram analisados estatisticamente através dos testes de aderência à curva normal, teste de Bartlett, teste de Friedman e teste de Wilcoxon, visando avaliar a eficácia do HcT20 tanto na prevenção da queda acentuada do fluxo salivar durante a radioterapia quanto na hipofunção salivar no período pós-radioterapia. Os pacientes do grupo I, ao término da radioterapia, mantiveram o índice de fluxo salivar total não estimulado em relação aos valores basais; os do grupo II, que utilizaram a associação medicamentosa após radioterapia, apresentaram melhora acentuada no índice de fluxo salivar total não estimulado em relação ao basal; e o uso do HcT20 apresentou melhor resultado quando utilizado durante a radioterapia. / The treatments used to prevent the xerostomy do not reach the efficiency expected by the patients, and it can have undesirable effects. The goal of this report was to make a quantifiable evaluation of the total non stimulated salivary flow index in patients with head and neck cancers during and after the exclusive radiotherapy with an association of lauryl-diethylene-glycol-ether sodium sulfate and calcium hydroxide (HcT20). This study was held at the hospital Dr. Hélio Angotti involving thirty one patients (n=31) divided into two groups: Group one had seventeen patients (n=17) submitted to fractioned radiation treatment in the head and neck region at the total dose of 7.000 cGy and had HcT20 during the treatment. Group two with fourteen patients (n=14) started with the use of HcT20 after the end of radiotherapy. A weekly and measured collection of the index of the total non stimulated saliva flow was done on the patients of both groups. The values that were obtained were analyzed statistically through the Bartlett test, the Friedman test and the Wilcoxon test, to seek an evaluation of the effectiveness of the medication on the prevention of the intense drop of the salivary flow during the radiotherapy and do avoid the xerostomy during the postradiotherapeutic period. The patients from group one at the end of the radiotherapy kept the base index of the total non stimulated salivary flow, the ones from group two that used the medication association after the radiotherapy had a great improvement of the total non stimulated salivary flow and the usage of HcT20 had a better result on the index of salivary flow during the radiotherapy.

Peanut, a major allergenic food, has life-threatening potential and is difficult to be totally avoided due to its common use in processed foods. Thermal processing can influence the allergenic properties of peanuts. However, the kinetics of the reactions caused by thermal processing has not been characterized. In our study, kinetics of the commonly used thermal processing methods on a commercial peanut cultivar (Virginia) using five time intervals was conducted. Water-soluble and SDS-sample buffer soluble proteins were extracted sequentially, and analyzed by sodium-dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and western-blot using human plasma containing IgE antibodies. The relationships between thermal processing (time) and log transformed water-soluble/total extractable major allergen content could be explained by a simple linear regression kinetic model for most of the processing methods (except high-pressure steaming). Among all the methods with optimal processing point, frying for 6 min had relatively lower IgE binding (linear epitopes) ratio may be due to the fact that this processing condition causing break down, cross-linking and aggregation of Ara h 2, and relatively lower solubility. Besides thermal processing, enzymatic processing also is considered to be an effective method in the allergenicity of peanuts. Eleven peanut lines (Coded MS-1~MS-11, MS-9 is the check and a common cultivar namely Valencia) were pre-screened from 122 peanut lines harvested in 2015 for allergen levels. These pre-screened lines were re-planted in 2016 for further analysis. One line, MS-7, was selected for lower Ara h 1 (8.5-9.5% of total protein) and Ara h 2 (4.2-6.6% of total protein) content in 2015 and 2016. Roasted MS-9 (check) peanut powders were used for enzymatic treatment for enzyme selection. A first order kinetic reaction model was conducted to describe the relationship between enzyme concentration (0-400AzU/g) and IgE-binding property reduction. Among eight food-grade enzymes, bromelain, papain and ficin hydrolysates had lower IgE-binding properties in terms of high IgE-binding property reducing rate (K, ≥ 0.4) and were selected for the following study. MS-7 (selected) & MS-9 (at level of 200AzU/g) hydrolyzed by three selected enzymes (200AzU/g) were used for IgE binding property comparison, TGase crosslinking and functional properties study. After hydrolyzed by the selected enzymes (200 AzU/g), the emulsion and foaming stabilities were decreased. Emulsion and foaming stabilities were increased in TGase (5U/g protein) crosslinked hydrolysates, which were even higher than soy protein isolate (SPI). The IgE-binding properties of TGase treated hydrolysates were similar to the hydrolysates without TGase treatment. MS-7 hydrolysates (with/without TGase) possessed less IgE-binding properties and similar functionality as compared with MS-9 hydrolysates.

No description available.