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Study on the thermodynamics of bovine serum albumin aqueous solutions: experiments, modeling and molecular simulations. / Estudo sobre a termodinâmica de soluções aquosas contendo albumina de soro bovino: experimentos, modelagem e simulação molecular.Luís Fernando Mercier Franco 27 November 2015 (has links)
The interaction between two proteins into salt aqueous solutions is investigated throughout this thesis. Experiments, modeling and molecular simulations were carried out to get a better understanding of the phenomenon. Bovine serum albumin was used as a model protein. An analytical expression for the structure factor for globular proteins in aqueous solution is presented in this work. This expression was obtained considering an intermolecular potential given by the sum of a hard core, a van der Waals attractive and a screened Coulomb contribution. Experimental data of Small Angle X-Ray Scattering for bovine serum albumin in aqueous solutions containing sodium salts at different protein concentrations and pH values are also presented. The expression developed for the structure factor describes accurately these experimental data provided a dependence of the attractive parameter on protein concentration is established. An expression for the osmotic pressure was derived from the structure factor. With attractive parameters adjusted from X-ray scattering data, the osmotic pressure of bovine serum albumin aqueous solutions could be predicted with very good agreement with experimental data. A derivation of the thermodynamic potentials, such as the chemical potential, using the new osmotic equation of state is presented. Applying the phase equilibrium criterion, the fluid-fluid phase equilibrium for bovine serum albumin in salt aqueous solution was calculated. Although such separation was not experimentally observed at the isoelectric point, it was indeed experimentally observed for a pH value below the isoelectric point. The predictions seem to be valuable to discuss how ion specificity affects the phase diagram of proteins. To apply molecular dynamic techniques to simulate how proteins interact to each other in salt aqueous solutions, two new coarse-grained force fields are proposed. The first one, meant for sodium sulfate aqueous solution, avoids the unphysical association observed for non-polarizable atomistic force fields; and allows the prediction of thermodynamic and dynamic properties. The second one, meant for bovine serum albumin in aqueous solution, is used as a new strategy to evaluate the scattering form factor of proteins as a low resolution technique for protein structure prediction. / Nesta tese apresenta-se uma investigação sobre a interação entre duas proteínas em soluções aquosas salinas. Experimentos, modelagem e simulações moleculares foram realizadas para conseguir um melhor entendimento do fenômeno. Albumina de soro bovina foi usada como proteína modelo. Uma expressão para o fator de estrutura de proteínas globulares em solução aquosa é apresentada neste trabalho. Esta expressão foi obtida considerando-se um potencial intermolecular dado pela soma de um núcleo duro, uma contribuição atrativa tipo vander Waals e uma contribuição de potencial coulômbico blindado. Dados experimentais de espalhamento de raios-X a baixos ângulos para a albumina de soro bovino em soluções aquosas contendo sais de sódio com diferentes concentrações de proteína e valores de pH também são apresentados. A expressão desenvolvida para o fator de estrutura descreve com precisão estes dados experimentais, desde que uma dependência entre o parâmetro atrativo com a concentração de proteína seja estabelecida. Uma expressão para a pressão osmótica foi derivada do fator de estrutura. Com parâmetros atrativos ajustados aos dados de espalhamento de raios-X, a pressão osmótica da albumina de soro bovino em solução aquosa pôde ser predita com grande correlação com os dados experimentais. Uma derivação dos potenciais termodinâmicos usando a nova equação osmótica de estado é apresentada. Aplicando o critério de equilíbrio de fases, foi possível calcular o equilíbrio fluido-fluido para a albumina de soro bovino em solução aquosa. Embora tal separação não tenha sido observada experimentalmente em um pH igual ao ponto isoelétrico, ela foi de fato observada experimentalmente para um valor de pH menor do que o ponto isoelétrico. As predições parecem ser valiosas para discutir como a especificidade iônica afeta o diagrama de fases de proteínas. De modo a avaliar como proteínas interagem umas com as outras usando técnicas de dinâmica molecular, dois novos campos de força coarse-grained são propostos. O primeiro, para o sulfato de sódio em solução aquosa, evita a associação não-física que é observada para campos de força atomísticos não-polarizáveis. Este modelo é capaz de prever propriedades dinâmicas e termodinâmicas. O segundo, para a albumina de soro bovino em solução aquosa, é usado como uma nova estratégia para avaliar o fator de forma de espalhamento de proteínas como uma ferramenta de baixa resolução na predição de estruturas proteicas.
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Estudo espectrosc?pico da intera??o entre flavon?ides e albumina s?rica bovina (ASB) / Spectroscopic study of the interaction between flavonoids and bovine serum albumin (BSA).Ribeiro, Alessandra Medeiros 19 March 2010 (has links)
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Previous issue date: 2010-03-19 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior, CAPES, Brasil. / Spectroscopic studies for several comercial flavonoids (flavone (FVA), alphanaphthoflavone (?-NAF), beta-naphthoflavone (?-NAF), thioflavone (TFA), S,Sdioxythioflavone (SDF), flavanone (FNA) and quercetin (QUE)), natural flavonoids
(biflavonoids such as agatisflavone (ATF), 7?-O-methylagatisflavone (OMA), amentoflavone
(AMF) and (DOF)) and thiochromanone (TCR) were performed in different solvents
(acetonitrile (ACN), ethanol (ETOH), cyclohexane (CEX), dichloromethane (DCM) and
milli-Q water (AD)). Irradiation of TFA, SDF and TCR in acetonitrile, employing the
nanosecond laser flash photolysis, lead to the formation of their corresponding triplet excited
state. Fluorescence emission spectroscopy studies showed that commercial and natural
flavonoids and thiochromanone are not fluorescent. UV/visible spectroscopy studies for QUE,
ATF, OMA, AMF and DOF, in the same previous solvents, revealed that for these flavonoids
the ground-state absorption spectrum in polar solvents, such as water or PBS (pH=7.4), is
completely different than the obtained in dichloromethane. This difference is more
pronounced for ATF. For DOF the absorption spectrum in water shows remarkable variations
when compared to that in PBS. The interaction between BSA and the flavonoids QUE, ATF,
OMA, AMF and DOF in PBS solution, pH = 7.4, was studied by UV/visible spectroscopy,
fluorescence emission spectroscopy, circular dicroism and molecular modelling. From these
studies it was clearly demonstrated that the interaction observed was directly dependent on the
flavonoid concentration and almost independent on temperature variation. The ground state
absorption spectrum for BSA showed a hypsochromic effect on the absorption band around
208 nm, corresponding to the n?* transition of the BSA ?-helix structure, as a function of
flavonoid concentration. Similar behavior was observed for the absorption at 280 nm,
corresponding to the tryptophan absorption in BSA. The fluorescence emission spectrum for
BSA in the presence of QUE, ATF, OMA, AMF and DOF, in PBS, at T = 22?C, 27?C, 32?C,
37?C and 42?C, shows a blue-shift on the protein emission as a function of flavonoid
concentration. These results suggest that the BSA chromophore is in a more hydrophobic
environment when compared with that sensed by the protein in the absence of the flavonoid.
In this case, quenching of BSA fluorescence (tryptophan residues) was clearly observed with
the high values obtained for the quenching rate constant kq (? 1013 to 1014 L/mol.s) indicating
a static quenching process. The distance (r) observed for the tryptophan residues and the
flavonoids was smaller than 7 nm, which indicates that there is a reasonable probability for a
non-radiative energy transfer process between tryptophan and the flavonoids, based on the
F?rster theory for energy transfer. Circular dicroism results at T = 25?C, 37?C and 42?C
revealed a significant decrease on the ?-helix percentage for BSA at 208 nm and 222 nm,
corresponding to the n?* transition for the secondary structure of BSA, as a function of
flavonoid concentration. These effects can be attributed to the formation of a complex
BSA/flavonoid which can induce conformational variations on the BSA structure. Molecular
modelling indicates that the main regions for the interaction between flavonoids and ASB are
located in hydrophobic cavities on the sub-domains IB and IIA, which contain tryptophan
residues (Trp-158 and Trp-237). A large hydrophobic cavity containing the Trp-237 is present
in the sub-domain IIA, which is responsible for the formation of the complex flavonoid-BSA
through a strong interaction flavonoid-tryptophan. / Estudos espectrosc?picos para diversos flavon?ides comerciais (flavona (FVA), alfanaftoflavona (?-NAF), beta-naftoflavona (?-NAF), tioflavona (TFA), S,S-di?xidotioflavona
(SDF), flavanona (FNA) e quercetina (QUE)), flavon?ides naturais (biflavon?ides como
agatisflavona (ATF), 7?-O-metilagatisflavona (OMA), amentoflavona (AMF) e
diidroochnaflavona (DOF)) e tiocromanona (TCR), foram realizados em diferentes solventes
(acetonitrila (ACN), etanol (ETOH), cicloexano (CEX), diclorometano (DCM) e ?gua millliQ (AD)). A irradia??o de TFA, SDF e TCR, em acetonitrila, por fot?lise por pulso de laser de
nanossegundo, levou ? forma??o de seus respectivos estados excitados triplete. Por
espectroscopia de fluoresc?ncia, verificou-se que os flavon?ides comerciais e naturais, e a
tiocromanona n?o apresentam emiss?o de fluoresc?ncia. Por espectroscopia de absor??o no
ultravioleta/vis?vel (UV-Vis) para QUE, ATF, OMA, AMF e DOF, nestes solventes,
percebeu-se que os espectros em presen?a de solventes polares, como AD, foram bem
diferentes dos espectros em DCM, principalmente, para ATF, e os espectros em solu??o de
tamp?o PBS (pH = 7,4) foram semelhantes aos em AD, exceto para DOF, apresentando
mudan?as substanciais. A intera??o entre ASB e os flavon?ides (QUE, ATF, OMA, AMF e
DOF) em solu??o tamponada (PBS, pH = 7,4) foi estudada por espectroscopia no
ultravioleta/vis?vel, espectroscopia de emiss?o de fluoresc?ncia, dicro?smo circular e
modelagem molecular sendo diretamente dependente da concentra??o adicionada de
flavon?ides e muito pouco dependente com a varia??o da temperatura. No UV-Vis ocorreu
deslocamento para o azul das bandas de absor??o pr?ximas a 208 nm (correspondente a ASB,
referente ?s transi??es n?* da estrutura ?-h?lice da albumina) e 280 nm (correspondente ao
triptofano da ASB), em fun??o do aumento de concentra??o dos flavon?ides. Na
espectroscopia de fluoresc?ncia (T = 22?C, 27?C, 32?C, 37?C e 42?C) houve deslocamento
para o azul na emiss?o da prote?na com o aumento da concentra??o dos flavon?ides,
sugerindo que o crom?foro da ASB est? em um ambiente mais hidrof?bico em rela??o ?quele
quando para ASB livre. Neste caso, observou-se supress?o da fluoresc?ncia de ASB (res?duos
de triptofano), como consequ?ncia de um processo de supress?o est?tica como demonstrado
pelos altos valores observados para kq (? 1013 a 1014 L/mol.s). A dist?ncia entre os res?duos de
triptofano e os flavon?ides (r) foi menor que 7 nm, um indicativo da grande probabilidade de
ocorrer transfer?ncia de energia entre ASB e flavon?ides, de acordo com a teoria de
transfer?ncia de energia n?o-radiativa de F?rster (Teoria de F?rster). No dicro?smo circular (T
= 25?C, 37?C e 42?C) foi verificada uma diminui??o do % de ?-h?lice da ASB em 208 nm e
222 nm (regi?es de transi??o n?* da estrutura secund?ria ?-h?lice da ASB no espectro de
absor??o UV), devido ao aumento de concentra??o dos flavon?ides. Esses efeitos podem ser
atribu?dos ? forma??o de um complexo flavon?ide-ASB que pode estar induzindo varia??es
conformacionais na ASB. Por modelagem molecular, atrav?s do programa docking, percebeuse que as regi?es principais para a liga??o dos flavon?ides com os s?tios de liga??o da ASB
est?o localizadas em cavidades hidrof?bicas nos subdom?nios IB e IIA (consistentes com os
s?tios I e II) e os res?duos de triptofano (Trp-158 e Trp-237) de ASB est?o nesses
subdom?nios, respectivamente. Existe uma grande cavidade hidrof?bica presente no
subdom?nio IIA, onde os flavon?ides podem se ligar com o res?duo de triptofano Trp-237
(melhor s?tio de liga??o), formando o complexo flavon?ide-ASB.
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Micro-injection moulded microneedles for drug deliveryNair, Karthik Jayan January 2014 (has links)
The emergence of microneedle (MN) technologies offers a route for a pain free, straightforward and efficient way of transdermal drug delivery, but technological barriers still exist which pose significant challenges for manufacture of MN systems with high volume outputs at low cost. The main aim of this research was to develop new ways for MN manufacture primarily using micro-injection moulding processes with high performance engineering thermoplastics. During the moulding process these polymeric melts will be subjected to extreme stress and temperature gradients and detailed material characterisation combined with in-line monitoring is desirable to optimise the moulding parameters and will help in achieving sharp microneedles with acceptable quality. Hence high shear rheology of these selected materials was performed at wall shear rates carried out in excess of 107 s-1 over a range of temperatures to predict the flow behaviour of polymer melts at such high shear strain rates. This information was fed into injection moulding simulation software tools (Moldflow) to assist the MN production process design. The optimal design was then used to produce a full 3D solid model of the injection mould and mould insert. Furthermore various design of experiments were conducted considering input parameters such as injection pressure, injection speed, melt temperature, filling time and mould cavity temperature. Response variables including product quality and data acquired from the cavity pressure and temperature transducers were used to optimise the manufacturing process. The moulded MNs were geometrically assessed using a range of characterisation techniques such as atomic force microscopy, confocal microscopy and scanning electron microscopy. An attempt to make hollow MNs was performed and encountered many challenges like partial cavity filling and part ejection during processing. Studies were carried out to understand the problem and identified the major problem was in tool design and improvements to the moulding tool design were recommended. Plasma treatment and mechanical abrasion were employed to increase the surface energy of the moulded polymer surfaces with the aim of enhancing protein adsorption. Sample surface structures before and after treatment were studied using AFM and surface energies have been obtained using contact angle measurement and calculated using Owens-Wendt theory. Adsorption performance of bovine serum albumin and release kinetics for each sample set was assessed using a Franz diffusion cell. Results indicate that plasma treatment significantly increases the surface energy and roughness resulting in better adsorption and release of BSA. To assist design-optimisation and to assess performance, a greater understanding of MN penetration behaviour is required. Contact stiffness, failure strength and creep behaviour were measured during compression tests of MN against a steel surface, and in-vitro penetration of MNs into porcine skin. The MN penetration process into porcine skin was imaged using optical coherence tomography. Finally, a finite element model of skin was established to understand the effect of tip geometry on penetration. The output of findings from this research will provide proof of concept level development and understanding of mechanisms of MN penetration and failure, facilitating design improvements for micro-injection moulded polymeric MNs.
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Improving Caco-2 cell permeability assay using phospholipid covered silica beadsFaradj, Lana January 2021 (has links)
The Caco-2 cell assay is widely used for in vitro permeability measurements. However, a draw back with the assay that this study will focus on improving, is compound adsorption to the plastic material. Lipophilic compounds such as Cyclosporin A and Peptide J, that will be used in this study, tend to bind to the plastic material in the assay. This can result in poor recovery and misleading permeability predictions. Bovine serum albumin (BSA) is an alternative used today to prevent this but is not always successful. The aim of this study is therefore to improve the Caco-2 permeability assay by adding phospholipid covered silica beads (PLB) to the basolateral chamber. The role of the PLB is to bind the compound of interest and decrease the amount of compound bound to the plastic material and thus better predict the permeability of the compound of interest. The PLB was produced using phosphatidylcholine and silica beads. Caco-2 cells were seeded and maintained for 21-29 days ahead of the experiment. PLB concentration of 20, 60 and 100 mg/ml were prepared. Samples were analyzed with HPLC-MSMS. The results showed that with increasing PLB concentration we had a significantly decrease in non-specific plastic binding resulting in reliable permeability predictions, concluding that the hypothesis was correct.
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Characterization and Preliminary Demonstration of Microcantilever Array Integrated SensorsAnderson, Ryan R. 07 July 2012 (has links) (PDF)
I characterize the behavior of microcantilever arrays which utilize the in-plane photonic transduction that I've previously developed and evaluate the performance of the microcantilever arrays in simple sensing scenarios with integrated microfluidics. First the thermal responses of microcantilevers with a variety of patterns of deposited gold films are compared. Using a scanning electron microscope, I observe the deflection thermal sensitivities of 300 µm long microcantilevers to be -170.82 nm/K for a full gold coating and -1.93 nm/K for no gold coating. Using the photonic transduction method I measure a thermal sensitivity of -1.46 nm/K for a microcantilever array with no gold. A microcantilever array integrated with microfluidics is exposed to a solution of bovine serum albumin (BSA) followed by solutions of various pH's. In all cases I observe a previously unreported transient deflection response. We find that the transient response is due to temporary nonuniform concentration distributions. In response to nonspecific binding of BSA, I observe a transient surface stress of -0.23 mN/m that agrees well with the -0.225 mN/m predicted by simulations. We hypothesize that the deflection response to pH changes is due to stress generated by conformational changes of bound BSA.The deflection response of an integrated microcantilever array to different types of flow and different flow rates is observed. Simulations of the deflection response match well with experimental results but disagree at higher flow rates. For flow rates greater than 200 µL/min, the limitation of the differential signal's dynamic range becomes apparent. We then investigate flow driven by an on-chip reciprocating reservoir pump. We demonstrate that it is possible to use the reciprocating pump to achieve high flow rates while making deflection measurements in-between reservoir actuations. Investigations of the microcantilever array noise show that flicker noise dominates below 10 Hz, while above 10 Hz, readout noise dominates. A minimum deflection noise density of 15 pW/√Hz is achieved. To improve the signal-to-noise ratio I develop algorithms for a digital lock-in amplifier with a digital phase-lock loop. In simulation the lock-in amplifier is able to improve the SNR by up to a factor of 6000, and self-lock to a noisy carrier signal without an external reference signal.
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Long-range Interactions and Second Virial Coefficients of Biomolecular MaterialsMa, Yingfang 09 February 2015 (has links)
No description available.
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The influence of different winemaking techniques on the extraction of grape tanninsNel, Anton Pieter 03 1900 (has links)
Thesis (MScAgric (Viticulture and Oenology))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: Grape and wine phenols consist of flavanols which is the building blocks for tannins.
These building blocks are called monomers which consist of catechins, epicatechins,
epigallocatechins and epicatechin-gallate. Tannin is important in wine as it contributes
to bitterness, mouth feel (astringency) and maturation potential of the wine. Futhermore
it has a health benefit as an antioxidant. Anthocyanins are responsible for the colour of
red wine. The anthocyanins combine with tannins to form stable polymeric pigments.
Due to the importance of tannins and anthocyanins in wine, it is imperitative that
different winemaking techniques are used to extract as much of these components as
possible and that the analysis is done quickly and accurately.
The aim of this study was to evaluate different winemaking techniques and their
extraction of tannins and anthocyanins into the wine. Too much tannin extraction can
have a negative effect on the sensory quality of the wine. Therefore a second aim was
to evaluate the mouth feel properties of a Shiraz wine. A third aim was to compare the
two tannin precipitation methods in terms of time efficiency, repeatability and the ease
of practice.
To investigate the amount of tannin concentration extracted by different winemaking
techniques, two cultivars (Cabernet Sauvignon and Shiraz) were used. These
treatments included the addition of an enzyme during fermentation [E], cold maceration
[CM], post maceration [PM] and the combination of cold and post maceration [CM+PM].
The grapes were harvested in two different climatic areas during the 2008 and 2009
vintages. The two climatic areas were classified according to the Winkler scale as a III
(Morgenster) and a IV (Plaisir de Merle). The grapes were harvested at two different
ripeness levels in order to evaluate the effect of the different winemaking processes on
the extraction of tannins and anthocyanins. One harvest was before (LB) and the other
after (HB) the commercial harvest.
The results of this study showed significant differences in the phenolic composition of
the wines. It was found that the warmer area showed higher tannin concentrations than
the cooler area for both cultivars. In the 2008 Cabernet Sauvignon the CM extracted
higher concentrations of tannin from the cooler area at both ripeness levels. In the
warmer area, CM extracted the highest tannin concentration HB, but the CM+PM
extracted the highest tannin concentration from Cabernet Sauvignon at the LB and CM
at the HB of the warmer area. In 2009 the PM extracted the highest concentration of
tannin at the lower ripeness level, while the E treatment extracted the highest
concentration from the warmer area. In the cooler area the CM+PM extracted the
highest concentration of tannin at a lower ripeness level, while there were no siginicant
differences between the different treatments at the higher ripeness level. The highest
anthocyanin concentration was found in the cooler area. The CM treatment was found
to have no effect on anthocyanin extraction.
Different methods are available to quantify the tannin concentration in wine. Two of the
most popular tannin analytical methods are the bovine serum albumin (BSA) and the
methyl cellulose precipitable tannin (MCP) methods. The BSA method is a very complex
method which uses at least 3 times more reagents than the MCP method. The MCP
method only analyzes tannins, while the BSA method analyzes tannins, monomeric
pigments (MP), small polymeric pigments (SPP) and large polymeric pigments (LPP).
In this study a good correlation was found between the two tannin precipitation methods
(R2 – 0.88). There is controversy regarding the variability of these methods. Some
scientists found that the two methods show a good correlation with HPLC, while others
found that there was no such correlation between the precipitation methods and the
HPLC. The MCP method had a practical advantage as it could be performed in half the
time required for the BSA method. This has a significant impact in scenarios where a
high sample throughput is required although it only measures total tannin.
The phenolic composition and mouth feel of the wine was strongly influenced by the
climatic area. In the warmer area the effect of tannin concentration on mouth feel was
much less than in the cooler area. The wine made of riper grapes, was more grippy,
bitter and numbing than the wines made from greener grapes. The E treatment was
especially associated with a dry, grippy sensation. / AFRIKAANSE OPSOMMING: Druif en wyn fenole bestaan uit flavanole wat weer die boublokke is van tanniene.
Hierdie boublokke, wat bekend staan as monomere, betsaan uit katesjiene,
epikatesjiene, epigallokatesjiene an epikatesjien-gallaat. Tanniene is belangrik in wyn
aangesien dit bydra tot bitterheid, mondgevoel (vrankheid) asook die
verouderingspotensiaal van wyn. As antioksidante hou dit ook gesondheidsvoordele in.
Antosianiene dra by tot die kleur van rooiwyn. Antosianiene kombineer met tanniene om
meer stabiele polimeriese pigmente te vorm. As gevolg van die belangrikheid van
tanniene en antosianiene is dit van uiterse belang dat verskillende wynmaak tegnieke
gebruik word om ekstraksie in die wyn te bevoordeel en dat die analitiese metode so
vinnig en akkuraat as moontlik gedoen word.
Die eerste doel van hierdie studie was om die ekstraksie van tanniene en antosianiene
deur middel van verskillende wynmaak tegnieke te evalueer. Te veel tanniene in die
wyn kan negatiewe sensoriese kwaliteit tot gevolg het. Daarom is die tweede doel om
die sensoriese kwaliteit van Shiraz wyn te evalueer. Die derde doel van hierdie studie
was die twee tannien presipitasie metodes met mekaar te vergelyk in terme van die
moeilikheidsgraad van die metode, tyd doeltreffendheid en herhaalbaarheid.
Verskillende wynmaak tegnieke (ensiem byvoegings [E], koue maserasie [CM],
verlengde dopkontak [PM] en ‘n kombinasie van koue maserasie en verlengde
dopkontak [CM+PM]) is vergelyk ten opsigte van tannien en antiosianien ekstraksie. In
2008 en 2009 is twee kultivars (Cabernet Sauvignon en Shiraz) in twee verskillende
klimatologiese areas gepars. Hierdie areas is geklassifiseer in die Winklerskaal as ‘n IV
(Plaisir de Merle) en ‘n III (Morgenster). Om die effek van die verskillende wynmaak
tegnieke op die ekstraksie van antosianiene en tanniene te vergelyk, is hierdie twee
kultivars by twee verskillende rypheidsgrade geoes. Die eerste oes was net voor
kommersiële oes (LB) en die tweede oes het net na kommersiële oes (HB)
plaasgevind. Die 2009 Shiraz wyn is organolepties beoordeel om die effek van die
verskillende wynmaak tegnieke op die wyn se mondgevoel te vergelyk.
Die resultate van hierdie studie toon beduidende verskille in die fenoliese samestelling
van die wyne. Dit is gevind dat die warmer area hoër tannien konsentrasies het as die
koeler area. In 2008 het die CM+PM die meeste tanniene uit die Cabernet Sauvignon
geëkstraheer by LB en die CM by HB in die warmer area. Die CM het in die koeler area
meer tanniene geëkstraheer by beide die LB en HB rypheidsgrade. In 2009 het PM die
meeste tanniene geëkstraheer by LB terwyl E die meeste tanniene geëkstraheer in die
warmer area. In die koeler area het CM+PM die meeste tanniene geëkstraheer, terwyl
geen van die behandelings ‘n effek gehad het by HB. Die meeste antosianien
konsentrasie was in die koeler area gevind as in die warmer area. In beide 2008 (LB en
HB) en 2009 (LB) het CM die meeste antosianiene geëkstraheer, terwyl geen
behandeling ‘n effek gehad het by HB.
Twee van die mees populêre tannien analitiese metodes is die BSA (bovine serum
albumien) en die MCP (metielsellulose presipitasie) metodes. Die BSA metode is ‘n
baie meer ingewikkelde metode waarvoor drie keer meer reagense gebruik word as vir
die MCP metode. Maar waar die MCP net tanniene ontleed, ontleed die BSA metode
tanniene, monomere (MP), klein polimeriese pigmente (SPP) en groot polimeriese
pigmente (LPP). Dit help indien daar gekyk wil word na die evolusie van polimeriese
pigmente.
In hierdie studie is bevind dat daar ‘n redelike korrelasie (R2 – 0.88) tussen die BSA en
MCP metode bestaan. Die herhaalbaarheid van die metodes het redelike kontroversie
veroorsaak, waar sommige navorsers bevind het dat die BSA metode nie so
herhaalbaar is soos eers bevind is nie. Die MCP metode het ’n praktiese voordeel
aangesien dit in die helfde van die tyd van die BSA metode uitgevoer kan word. Dit het
‘n groot impak indien ‘n groot hoeveelheid monsters ontleed moet word.
Die fenoliese samestelling en mondgevoel word sterk beïnvloed deur die klimatologiese
area. In die warmer area was die effek van tannien konsentrasie op mondgevoel kleiner
as in die koeler area. Die wyn van ryper druiwe het meer harder, verdowingseffek en
bitter nasmaak gehad as by die wyn van groener druiwe. Die ensiem behandeling was
meer geassossieerd met droë mond gevoel.
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Interakce mezi proteiny a huminovými látkami při koagulaci / Interactions between proteins and humic substances during coagulationNovotná, Kateřina January 2015 (has links)
This diploma thesis is focused on coagulation of humic substances (HS) and BSA (Bovine Serum Albumin) protein which was chosen as a representative of proteins contained in AOM (Algal Organic Matter). Additionally, possible interactions between these compounds were also investigated. It was found that the optimal dosage of coagulant is much higher for HS compared to BSA. The best removal of both HS and BSA was reached in slightly acidic pH range and it is attributed mainly to charge neutralization and adsorption mechanisms. The maximum removal rate was 70 % for humic substances and 80 % for BSA. The results show that BSA has a positive effect on coagulation of HS (resulting in a lower coagulant demand) and vice versa while BSA was removed more efficiently than HS. The existence of interactions between BSA and humic substantces during coagulation was demonstrated in certain pH ranges and it can occur even without the presence of coagulant. These interactions are highly dependent on pH that determines charge properties (and hence reactivity) of organic matters. Finally, the comparison of BSA and cyanobacterial proteins shows that their behavior during coagulation is similar. Consequently, BSA can be used as a model compound representing AOM proteins, especially their high molecular weight fraction....
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New NMR methods for mixture analysisHernandez Cid, Aaron January 2017 (has links)
This thesis is focussed on the investigation of matrices for matrix-assisted diffusion-ordered spectroscopy (MAD). Diffusion-ordered spectroscopy (DOSY) is a family of experiments where the resonances in the chemical shift dimension are further dispersed in an extra dimension according to diffusion coefficient. A typical DOSY spectrum shows one single diffusion coefficient for all the resonances coming from one single species. However, If two or more resonances overlap, the diffusion resolution of the DOSY spectrum is compromised and a spurious diffusion coefficient results, intermediate between the species. In case of signal overlap, the use of more advanced processing methods aids to separate two analytes that differ by at least 30% in diffusion coefficient. In practice, many mixtures contain species of similar diffusion coefficients whose resonances overlap in the chemical shift dimension. The addition of co-solutes can modify the chemical environment (matrix), with which different analytes interact to different extents, and enhance the diffusion resolution of DOSY. However, the addition of co-solutes can risk the benefits of DOSY by increasing the probability of signal overlap. Signal overlap in MAD is avoided by using a 1H NMR-invisible surfactant such as sodium perfluorooctanoate (NaPFO), which has replaced each proton by a fluorine atom. PFO micelles are a tunable matrix which allows the separation of analytes via coulombic interactions by adjusting the pH. Differences in diffusion coefficient in NaPFO solution can be analysed using a modified Lindman's law to model the diffusion coefficient as a function of pH. The model rationalises the binding constants of analytes to PFO micelles with good accuracy, subject to the spectral data quality. Another alternative to resolve diffusion coefficients using the invisible MAD approach is by means of a commercially available alkyl surfactant like cetyltrimethylammonium bromide (CTAB). CTAB in high ionic strength solution forms worm-like micelles whose resonances can be filtered out from the final DOSY spectrum. CTAB worm-like micelles have short transverse relaxation times compared to all of the analytes in the mixture. If a transverse relaxation filter is positioned at the beginning of a standard DOSY pulse sequence, as in PROJECT-Oneshot, the strong CTAB signals vanish and leave behind only the analyte resonances and hence avoid signal overlap. Finally, the use of bovine serum albumin (BSA) as a potential invisible matrix, using a similar approach to CTAB worm-like micelles is investigated, using a relaxation-weighted DOSY pulse sequence to suppress most of the BSA background signal (at a cost in analyte signal to noise ratio). An alternative to suppress most of the BSA background and preserve most of the analyte signal is by means of mild transverse relaxation filtration and spectral editing to obtain an edited DOSY spectrum that shows only the analyte signals. Nonetheless, it is a shame that useful MAD results can only be obtained under a narrow set of conditions: i) different mole ratios BSA: analyte to aid diffusion resolution, ii) mild T2 filtration to improve analyte signal to noise ratio and iii) spectral editing to remove residual BSA background.
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Particle and macromolecular fouling in submerged membraneNegaresh, Ebrahim, Chemical Sciences & Engineering, Faculty of Engineering, UNSW January 2007 (has links)
Particles and macromolecular components, including biopolymers (protein and carbohydrate), are viewed as the main foulants in the complex feed submerged membrane filtration systems such as membrane bioreactor (MBR). This work focused on two aspects of fouling in complex fluids: 1- Assessing fouling propensity and mechanisms for various model solutions. 2- Using of two specific solutions modelling biomass found in MBR for a better understanding of the fouling mechanisms in submerged MBR processes. Filtrations were carried out with 0.22 ??m PVDF hollow fibre membrane. Alginate was used as a model for polysaccharide, bovine serum albumin (BSA) as a model for protein, (un)washed yeast and bentonite were representing suspended solid contents. According to the data obtained during this study the fouling propensity of each model solution was classified as follow in a decreasing order: Alginate > unwashed yeast > washed yeast > BSA > bentonite for one-component solutions; and Alginate-washed yeast > Alginate-BSA > Alginate-bentonite > Alginate-unwashed yeast for two-component solutions. Introducing the alginate increased the reversible fouling (except BSA). Passive adsorption had a significant effect on fouling of alginate even before the beginning of the filtration. Washed yeast and a mixture of washed yeast + BSA were then used as model solutions to simulate the activated sludge found in MBR. The concentration of washed yeast and BSA used in this study were calculated in order for the characterisations of the two model solution to match (in terms of biopolymer contents) those of MBR biomasses reported in the literature. By rinsing, backwashing and chemical cleaning of the membrane, three fouling layers of upper, intermediate and lower were defined respectively. Results obtained from the analysis of the biopolymers found in the cleaning solutions allow a better understanding of the fouling mechanisms occurring for the two model solutions used in this study: for washed yeast, the lower layer and for washed yeast + BSA , the upper and intermediate layers were found to have relatively high biopolymeric composition. This was explained by higher concentration of solids on the membrane surface and by higher biopolymer interactions when washed yeast was mixed with BSA.
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