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1
Potužák, Marcel. "Physico-Chemical Properties of Silicate Melts." Diss., lmu, 2006. http://nbn-resolving.de/urn:nbn:de:bvb:19-55228.
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Folmer, Britta M. "Physico-chemical characterisation of novel surfactants /." Stockholm : Tekniska högsk, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3052.
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Jordan, Peter A. "Physico-chemical studies of aluminium biochemistry." Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294654.
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Lim, Wen Huei. "Physico-chemical properties of ultraflexible vesicles." Thesis, King's College London (University of London), 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417109.
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Gupta, Saloni. "Physico-chemical properties of polypropylene glycols." Thesis, University of Greenwich, 2015. http://gala.gre.ac.uk/21538/.
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Poly(propylene glycol) (PPG) samples of different molecular mass were characterized using differential scanning calorimetry, modulated differential scanning calorimetry, thermogravimetry and thermally stimulated current (TSC) spectroscopy. It was shown, by TSC, that the glass transition temperature and the degree of molecular mobility increased with increasing molecular mass of PPG. Additional experiments showed that PPGs of molecular mass 425, 1000 and 2000 Da undergo one global relaxation process; however, PPG 2700 (Da) undergoes an additional relaxation process after the glass transition which has been attributed either to the release of the excess charge delocalised in the polymer structure or a liquid-liquid transition. Thermally induced phase separation in aqueous solutions of PPG has been examined using a variety of techniques including high sensitivity scanning calorimetry (HSDSC), hot stage microscopy, small angle neutron scattering, and turbidity measurements. The data suggest that phase separation is a consequence of PPG aggregation (droplets); the aggregates grow in size, as the temperature is raised further. It is postulated that phase separation occurs via nucleation and growth, which is corroborated by model fitting the calorimetric data using a mass action aggregation model. It is concluded that phase separation of PPG occurs as a result of the disruption of a hydrogen bonded network between water and PPG. The effect of five sugars (mannitol, maltose, raffinose, sucrose and trehalose) on the Tm (transition temperature) of aqueous PPG 1000 solutions was studied by HSDSC and turbidity measurements. All the sugars decreased the phase separation temperature of the PPG solutions, with trehalose and maltose showing the greatest effect. A series of experiments, using HPLC, showed that phase separated PPG (1000 Da) increased the apparent aqueous solubility of naphthalene.
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Powell, Francis E. "Physico-chemical studies in flow analysis." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/25925.
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The first part of this study was the characterisation of an impinging jet electrode in an amperometric detector; the device having found extensive application in flow injection analysis. A voltammetric study of the detector in the stopped flow mode was carried out and evidence is presented of restricted diffusion imposed by the shallow depth of the cell. In hydrodynamic voltammetry, the detector exhibited a gradual progression from thin-layer to wall jet behaviour as the flow rate increased. This gradation is discussed in terms of a model in which flow in the electrode chamber forms concentric rings, the streamlines being successively perpendicular, oblique and parallel to the electrode. The response of the detector and its associated equipment was studied by two experiments. Firstly, the fidelity of the electrochemical instrumentation and recording system was ascertained from its electronic response to a RC (resistance-capacitance) circuit functioning as a flow injection transport analogue. Secondly, the dynamic response of the electrochemical cell was established from an experiment using a concentration step input delivered through a short, straight manifold. The results indicated that laminar flow in the delivery tube was modified by mixing stages in the cell channel and its connections to produce a final dispersion which defines an effective detection volume of only 7μL. The electronic and cell responses indicate that the total detection system would impose little extra dispersion in a practical flow injection line. In the second part of this study, photometric titrations were carried out in a stirred tank reactor in which the volume changed linearly with time. The general relation for the concentration gradient when the tank is used as a mixing device was examined experimentally under various flow conditions. In particular, the precision of linear concentration gradients was ascertained when peristaltic pumping was employed. These gradients were utilised to titrate analyte within the tank by means of titrant delivered by pump flow with photometric detection in an exit stream. Self-indicating titrations, following changes in the absorbance of analyte, titrant or reaction product, were performed each conforming to theoretical prediction. Due to the external detection system employed, dispersion and transportation lag effects were observed and accounted for.
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Díez, Orrite Silvia. "Physico-chemical properties of polymers at interfaces." Doctoral thesis, Universitat Rovira i Virgili, 2002. http://hdl.handle.net/10803/8511.
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A polymer is a large molecule constructed from many smaller structural units calledmonomers joined together by covalent bonds. Polymers have existed in natural form
since life began and those such as DNA, RNA, proteins and polysaccharides are some
of the most important macromolecules found in plant and animal life. From the earliest
times, the man has used many of these polymers as materials for providing clothing,
decoration, tools, weapons and other requirements. However, the origins of today's
polymer industry commonly are accepted as being in the nineteenth century when
important discoveries were made concerning to the modification of certain natural
polymers, as cellulose. The use of synthetic and natural polymers as stabilisers for
colloid systems (sols, dispersions, microemulsions, etc.) is becoming more important
everyday in contemporary life. Polymer additives can be applied in preconcentrations
and dehydration of suspensions in mineral processing, purification of wastewater and
even in nutritional and pharmaceutical emulsions being their importance related to the
characteristics of the process and the properties that they show. The present work aims
to develop appropriate numerical and analytical modelling techniques, which can
describe (considering the formation of loops and tails) the structure of a polymeric layer
adsorbed on heterogeneous surfaces; this adsorbed layer is an relevant factor in the
properties showed by this kind of materials. Taking into account this, the methodology
known as Single Chain Mean Field (SCMF) (originally used to study micellar
aggregates and grafted polymers) was modified to apply on polymer adsorption
problems. In this way, it was possible to calculate numerically properties that can be
experimentally measured, such as total monomer volume fraction profiles, loop and tail
volume fraction profiles, adsorbance or the thickness of the adsorbed layer. The
structure of the polymeric layer was examined both for flat and spherical (colloidal
particles) surface geometries. When compared with other well established
methodologies for the numerical simulation of polymeric systems, this new version of
SCMF was found to be more efficient due to the improved sampling of the polymer
chain configuration space.
Thus, SCMF method results, in the case of the adsorption on flat surfaces, compare well
with those obtained either with Monte Carlo simulations or with the method developed
in the 80s by Scheutjens and Fleer (SCF). Due to the lack of studies focusing to polymer
adsorption on colloidal particles, our results have been the first to present quantitative
predictions of the structure of the polymeric layer adsorbed on a spherical surface. Thus,
we have demonstrated the dependence of the adsorbed polymer layer with the size of
the colloidal particle as well as the characteristic lengths that influence on it. Finally, in
this work an analytical approach for the description of polymer-colloidal mixtures has
been developed which compares well with the numerical results obtained from the
SCMF methodology. Furthermore, the analytical approach is able to predict system
behaviours, as for example the formation of gels.
Un polímero es una molécula de grandes dimensiones formada de pequeñas unidades
llamadas monómeros, los cuales se encuentran unidos por medio de enlaces covalentes.
Los polímeros han existido de forma natural desde el comienzo de la vida, y aquellos
como el DNA, RNA o las proteínas son algunos de los polímeros más importantes
encontrados tanto en la vida animal como en la vegetal. Desde siempre el hombre ha
utilizado muchos de estos polímeros como materiales para hacer ropa, decoración,
herramientas, etc. Sin embargo, el origen de la industria de polímeros que conocemos
hoy en día se produjo en el siglo 19, gracias a importantes descubrimientos dentro de la
modificación de ciertos polímeros naturales, como la celulosa. El uso de polímeros
sintéticos y naturales como estabilizadores de sistemas coloidales (dispersiones,
microemulsiones, etc.) juega en nuestros días un papel importante. Los polímeros
utilizados como aditivos, pueden ser aplicados en preconcentraciones y deshidratación
de suspensiones dentro de procesos minerales, tratamiento de aguas residuales e incluso
los podemos encontrar dentro de la industria farmacéutica y alimentaria, donde su
importancia es debida a la procesabilidad y propiedades que ellos exhiben. El trabajo
que se presenta es orientado al desarrollo de técnicas de modelización, tanto analíticas
como computacionales, y su aplicación en la descripción (por medio de la formación de
bucles y colas) de la estructura de la capa de polímeros adsorbida en superficies
heterogéneas, siendo dicha capa de polímeros un factor importante en las propiedades
que este tipo de materiales presentan. Con este propósito, la metodología conocida
como Single Chain Mean Field, utilizada anteriormente tanto para el estudio de
agregados micelares como de polímeros anclados en superficies, ha sido modificada
para describir la adsorción de polímeros en superficies. Así se han podido calcular
numéricamente propiedades medibles experimentalmente como los perfiles de la
fracción en volumen de monómeros totales, además de los pertenecientes a los bucles y
colas, adsorbancia o el espesor de la capa adsorbida, para geometrías de la superficie
absorbente tanto plana como esférica (partículas coloidales). En su comparación con
otras metodologías, ya establecidas para la simulación numérica dentro de la física de
polímeros, la aplicación de esta nueva versión del Single Chain Mean Field (SCMF)
ha resultado ser más eficiente debido a un mejor muestreo del espacio de
configuraciones de las cadenas poliméricas. De este modo, comparando los resultados
obtenidos a partir del SCMF, con aquellos obtenidos mediante técnicas de simulación
Monte Carlo o la teoría desarrollada en los años 80 por Scheutjens y Fleer (SCF), se ha
podido encontrar un buen acuerdo en las propiedades calculadas para el caso de la
adsorción en superficies planas. Debido a la dificultad intrínseca del estudio de la
adsorción en superficies curvadas, nuestros resultados son los primeros que presentan
predicciones cuantitativas sobre la estructura de la capa que se forma sobre una
partícula coloidal. Así hemos podido comprobar la dependencia de la estructura de la
capa de polímeros adsorbidos con el tamaño de la partícula sobre la que se encuentran
adsorbidos además de las longitudes características de las cuales depende. Finalmente,
en este trabajo se ha desarrollado, también, una teoría analítica para la descripción de la
mezcla polímero-coloide. De este modo, los resultados numéricos obtenidos con el
SCMF han podido ser comparados con dicha teoría, obteniendo, de nuevo, un buen
acuerdo y predecir, además, comportamientos colectivos como la formación de geles.
8
Sellaturay, S. V. "Physico-chemical basis for struvite stone formation." Thesis, University College London (University of London), 2011. http://discovery.ucl.ac.uk/1336882/.
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Introduction: Struvite stones (magnesium ammonium phosphate) account for 10-15% of renal stones and can grow rapidly forming staghorn calculi. With limited medical therapies available and surgery the mainstay of treatment, an understanding of the physico-chemical conditions causing struvite crystallization allows development of strategies to prevent their formation. At present, very little is known about the physico-chemical conditions that result in struvite crystallisation. This lack of understanding has two bases: i) the particular ionised concentrations of the reactants (e.g. Mg2+, NH4+, and phosphate) in the urine are unknown; ii) the prevailing chemical conditions that would modulate crystallisation are also unclear (e.g. pH, osmolality, other urinary constituents).Recent advances in the development of ion-selective electrodes allows accurate determination of urinary constituents in small (<1ml) undiluted samples. Methods: We have furthered developed an NH4+-ion selective electrode and magnesium ion-selective electrode to measure the urinary concentrations of each to aid our understanding of struvite deposition. [NH4+] and [Mg2+] were measured using plastic dip cast ion-selective electrodes dispersed in suitable plasticisers, using nonactin for NH4+ and several different neutral ligands for Mg2+. Data were validated against standardised and developing methodology, including colour spectrophotometry and computational algorithms. Urine samples were also subjected to analysis using clinical biochemical techniques. Results: We characterised an NH4+-ion selective electrode and made the first measurements of [NH4+] in undiluted urine samples, in normal subjects and those with stone disease. This technique was validated using colour spectrophotometry and then the technique was used to validate a computational algorithm. We have developed and characterised the Mg2+-ion-selective electrode but Ca2+ caused significant interference. Conclusions: Direct measurement of the urinary [NH4+] has been achieved for the first time with a value of about 25mM. This exciting new technique may now provide clinicians with an important point-of-care investigative tool in diagnosing and monitoring struvite calculogenesis.
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Maciejczyk, Malgorzata. "1,3,2-Benzodiazaboroles : synthetic and physico-chemical studies." Pau, 2010. http://www.theses.fr/2010PAUU3008.
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There is considerable current interest in conjugated organic compounds containing threecoordinate boryl substituents as π-acceptors, as the vacant pz-orbital on boron is capable of significant interaction with an organic π-system. But as boron is less electronegative than carbon, the boryl moiety may also act as α-donor. These boron containing compounds exhibit intriguing fluorescence emission, second and third order non-linear optical properties and fluoride sensing ability. They can serve as emissive and/or electron-transport layers in organic light emitting devices (OLED). Materials with phenylethynyl scaffolds as π-electron conducting units have been intensively studied according to optical and physical properties of oligo- and poly-(p-arylene)ethynes, including those substituted by donor- and/or acceptor functions. This work is followed in collaboration with Pr Weber group at Bielefeld University, which has a long-standing interest in the chemistry of 1,3,2-diazaboroles. Thereby, our studies were carried out on syntheses and the electronic properties of simples and progressively extended π-conjugated systems with 1,3,2-diazaborolyl- and 1,3,2-benzodiazaborolyl- substituents, with the particular interest focused on the influence of substituents on the spectroscopic properties when additional donor functionalities are present in the molecules. Quantum chemical calculations [DFT, TD-DFT, OVGF] have been applied to provide information on the physico-chemical properties and electronic structure of following molecules: 1,3-Diethyl-1,3,2-diazaboroles, 1,3-Diethyl-1,3,2-benzodiazaboroles, 2-Arylethynyl-1,3,-diethyl-1,3,2-benzodiazaboroles, 2[3’-cyano-4’-phenylethynyl]phenyl-1,3,-diethyl-1,3,2-benzodiazaboroles, and finally N-carbazolyl- and Ncarbazolyl-2’-thienyl- functionalizedIl existe actuellement un intérêt considérable pour les composés organiques conjugués contenant des ligands avec l’atome de bore en tant que π accepteur, puisque l’orbitale pz vacante de cet atome peut interagir de manière significative avec un système π organique. Mais comme le bore est moins électronégatif que le carbone, il peut aussi agir comme α-donneur. Il s’avère que ces composés sont doués de propriétés particulièrement intéressantes du point de vue de l’optique non linéaire de second et de troisième ordre. Ils peuvent servir d'émetteur et/ou de transporteur d’électron dans les couches organiques dans les diodes électroluminescentes (OLED). Les matériaux avec le groupement phenyléthynyl en tant que unité de transport d’électrons π a été intensivement étudié par rapport à leurs propriétés optiques et physiques comme oligo- et poly-(p-arylene)ethynes, en incluant ceux substitués par des fonctions donneur - et/ou accepteur. Ce travail est mené en collaboration avec le groupe du Pr Weber de l'Université Bielefeld, qui s’intéresse de longue date à la chimie des 1,3,2-diazaboroles. Ainsi, nos études ont portées sur les synthèses et les propriétés électroniques de systèmes π conjugués simples et ont progressivement été étendues aux substituants 1,3,2-diazaborolyl- et 1,3,2-benzodiazaborolyl, avec un intérêt particulier sur l'influence de substituants sur les propriétés spectroscopiques quand les fonctions additionnelles donneurs sont présentes dans les molécules. Les calculs quantiques [DFT,TD-DFT,OVGF] ont été effectués pour obtenir des renseignements sur les propriétés physico-chimiques et la structure électronique de molécules suivantes : 1,3-diéthyl-1,3,2-diazaboroles, 1,3-diéthyl-1,3,2-benzodiazaboroles, 2-aryléthynyl-1,3,-diéthyl-1,3,2-benzodiazaboroles, 2[3’-cyano-4’-phényléthynyl]phenyl-1,3,-diéthyl-1,3,2-benzodiazaboroles et finalement N-carbazolyl-et N-carbazolyl-2’-thiényl-functionalized compounds
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Kalogianni, Eleni P. "Physico-chemical and chemical changes during repeated deep-frying of potatoes." Thesis, University of Lincoln, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441670.
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Torbensen, Kristian. "Physico-Chemical and Microfluidic Approaches Toward Engineering Oscillating and Communicating Chemical Droplets." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066707/document.
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La génération, propagation et la réception d’informations (bio/chimiques) entre les organismes individuels sont la clé de voûte de nombreux systèmes communicants intelligents et sont omniprésents dans la nature. Les colonies de lucioles synchronisent leurs flashs, et la contraction et l’expansion des muscles cardiaques sont quelques exemples parmi d’autres, où les signaux bio / chimiques générés par des sources synchronisées produisent un comportement coopératif. L’objectif final de cette thèse est de développer une plateforme fiable pour générer des réseaux de communication de liposomes, en encapsulant la réaction de Belousov-Zhabotinsky (BZ) en tant que source d’information ou un signal transmis, et d’étudier la dynamique d’un tel système. Pour atteindre cet objectif, plusieurs questions ont été abordées par une approche “bottom-up” et multi-échelle. Tout d’abord, nous avons étudié l’interaction entre des liposomes de DMPC dopés et non-dopés avec le cholestérol, l’acide myristique, tétradécylsulfate, tétradécylamine, et les espèces impliquées dans la reaction BZ en utilisant la diffusion de rayons X aux petits angles et par spectrophotométrie UV-visible. Des rangées 1D de micro-gouttelettes ont été fabriquées en encapsulant la réaction BZ en microgouttelettes au moyen de la microfluidique et la communication entre les gouttelettes adjacentes a été étudiée. Plus tard, nous avons démontré un système microfluidique facile à monter / démonter avec une conception robuste et une géométrie modulable pour générer des emulsions doubles d’eau dans l’huile dans l’eau (E/ H / O). Enfin, le comportement de ces doubles emulsions générées dans système microfluidique en utilisant des phosphoplipides comme tensioactif et du chloroforme comme phase huileuse, est rapporté. Nous avons montré, avec cette composition de la phase d’huile, que le comportement dynamique des émulsions doubles sous écoulement donne lieu à des phénomènes riches incluant la déformation et du “tip-streaming”Generation, propagation and reception of (bio/chemical) information between individual organisms are the keystone of many intelligent communicating systems, and are ubiquitous in Nature. Colonies of fireflies synchronize their flashes, and contraction and expansion of heart muscles are few examples among others, where bio/chemical signals generated by synchronized sources produce a cooperative behaviour. The final objective of this thesis is to develop a reliable platform for generating communicative networks of liposomes, encapsulating the Belousov-Zhabotinsky (BZ) reaction as source of information or transmitted signals, and to study the dynamics of such a system. To reach this goal, several issues were addressed by following bottom-up and multi-scale approaches. First we investigated the interaction between both bulk DMPC liposomes, and liposomes doped with cholesterol, myristic acid, tetradecylsulfate, tetradecylamine, and the species involved in the BZ-reaction by using small angle X-ray scattering (SAXS) and UV-visible spectrophotometry. Than 1D arrays of micro-droplets were fabricated by encapsulating the BZ reaction into microdroplets by means of microfluidics, and the communication between adjacent droplets was studied. Later, we demonstrated an easy to assemble/disassemble and robust design for a microfluidic device with adjustable geometry, for generating monodisperse water-in-oil-in-water (w/o/w) double emulsions. Finally, the behavior of w/o/w double emulsions generated in a microfluidic device, using phospholipids as surfactant and chloroform as the oil phase, was reported. We showed, with this composition of the oil phase, that the dynamic behaviour of the double emulsions under flow gave rise to different phenomena, such as deformation and tip-streaming
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Shoghi, Kalkhoran Elham. "Physico-Chemical Characterization of Drugs: Acidity and Solubility." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/98463.
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The aim of the present work was to contribute to establish robust and high throughput methodology of interest in the "Drug Discovery" step commonly done in pharmaceutical laboratories. This purpose involves the exploration of the possibilities of the potentiometric Sirius methodology to determine both acidity constants and solubilities of drugs and other bioactive compounds and also to do a study about how to improve bioavailability of a model drug, Amphotericine 8, by increasing its dissolution rate. In the first part of this project, the acidic dissociation enthalpies and constants of anilinium, protonated tris (hydroxymethyl)- aminomethane (HTris+), benzoic and acetic acids, have been determined at several temperatures in pure water and in methanol/water mixtures by potentiometry method. The pK(a) values determined by this technique are in accordance with those values determined by ITC method in our laboratory and also with those other values from literature. Also dissociation enthalpies can be obtained from potentiometric pK(a) values by means of the Van't Hoff approach and these obtained values are in agreement with those ones determined directly by calorimetry in our laboratory. In the second part, we focused on studying about solubility. The Chasing Equilibrium method offers an alternative to the classical procedures to measure the solubility of compounds with acid-base properties. The method is fast and yields accurate results. In this work, the solubility of several compounds including acids and bases was determined through the Chasing Equilibrium approach. A study of experimental conditions in terms of sample weight was performed to measure solubilities. The study shows that only a limited range of weights, depending on the nature and solubility of the compounds, is adequate to obtain reliable results. In the third part of this work, the solubility vs. pH profiles of five ionizable drugs of different nature (a monoprotic acid, a monoprotic base, a diprotic base and two amphoteric compounds showing a zwitterionic species each one) have been determined through two different methodologies: the classical Shake-Flask (S-F) and the potentiometric Cheqsol methods using in both instances the appropriate Henderson-Hasselbalch (H-H) or derived relationships. The results obtained independently from both approaches are consistent. A critical revision about the influence of the electrolyte used as buffering agent in the S-F method on the obtained solubility values is also performed. Thus, some deviations of the experimental points with respect the H-H profiles can be attributed to specific interactions between the buffering electrolyte and the drug due to the hydrotrophic character of citric and lactic acids. In other cases, the observed deviations are independent of the buffers used since they are caused by the formation of new species such as drug aggregates (cefadroxil) or the precipitation of a salt from a cationic species of the analysed compound (quetiapine). In the forth part, the objective was to compare the dissolution behavior of tablets prepared from solid dispersions prepared in DMSO dissolvent with and without drug-carrier and also with and without surfactants in aqueous and acidic solutions. Amphotericine B was used as a model drug. Two types of carriers were used; mannitol, inulin. Solid dispersions with two different drug loads were prepared by freeze drying method. It was found that the drug dissolution rate in aqueous and acidic solutions was significantly increased in the presence of drug-carrier and surfactants. X-ray powder diffraction revealed that all solid dispersions were fully amorphous.El objetivo del presente trabajo ha sido contribuir a establecer metodología robusta y de high throughput de interés en la etapa conocida como "Drug Discovery" que tiene lugar en los laboratorios farmacéuticos al inicio del proceso de desarrollo de nuevos fármacos. Este objetivo ha implicado la exploración de las posibilidades de la metodología potenciométrica establecida y comercializada por Sirius Analytical Ltd. para la determinación de las constantes de acidez y de la solubilidad de compuestos bioactivos y también un estudio sobre la mejora de la biodisponibilidad de un fármaco muy insoluble tomado como modelo mediante el aumento de su velocidad de disolución. En la primera parte de esta Tesis se han determinado potenciométricamente las constantes de disociación ácida y la variación de entalpía asociada de dos bases y dos ácidos tomados como modelo en agua pura y en mezclas de metanol/agua (0-60% w/w) a varias temperaturas (25-55°C). Esto ha implicado la puesta a punto de la estandarización del sistema potenciométrico en las condiciones de trabajo. Los valores de pK(a) determinados son concordantes con los que ofrece la literatura. Se han calculado también las entalpias de disociación en los distintos solventes binarios estudiados mediante la ecuación de Van't Hoff a partir de los valores experimentales de pK(a). La consistencia de los resultados obtenidos con los de la literatura, obtenidos directamente por calorimetría, confirma la robustez de la metodología. En la segunda parte de este trabajo, el estudio se centró sobre la determinación potenciométrica de la solubilidad de ácidos y bases mediante el método conocido como Chasing Equilibrium, como alternativa a los procedimientos clásicos de equilibración. El método es rápido y produce resultados precisos. Se ha realizado un estudio sobre las condiciones experimentales óptimas en términos de peso de la muestra para medir eficazmente la solubilidad. El estudio muestra que, en función de la naturaleza y solubilidad de los compuestos, existe un intervalo limitado de peso de muestra adecuado para obtener resultados fiables. En la tercera parte de la presente memoria, se estudian los perfiles de solubilidad en función del pH de cinco fármacos ionizables de naturaleza diferente, un ácido y una base monopróticos, una base diprótica y dos compuestos anfóteros que muestran una especie zwitteriónica cada uno. Se han determinado los perfiles de solubilidad mediante el método clásico de equilibración (Shake-Flak, S-F) y el potenciómétrico y, en ambos casos, se han utilizado las relaciones apropiadas de Henderson-Hasselbalch (H-H) o derivadas. Los resultados obtenidos de forma independiente por ambos métodos son consistentes. Se ha hecho un estudio crítico acerca de la influencia del electrolito utilizado como agente tampón en el método S-F en los valores de solubilidad obtenidos y se han observado algunas desviaciones de los puntos experimentales con respecto a los perfiles esperados que pueden ser debidas a interacciones específicas entre el electrolito tampón y el fármaco. En otros casos, las desviaciones observadas son independientes de los tampones utilizados y se pueden atribuir a la formación de nuevas especies tales como agregados iónicos del fármaco en estudio o la precipitación de una sal a partir de una especie catiónica del compuesto analizado. En la cuarta parte de esta memoria el objetivo ha sido estudiar la velocidad de disolución de comprimidos preparados a partir de dispersiones sólidas de un fármaco modelo con y sin portador del fármaco y también en presencia y en ausencia de tensioactivo en soluciones acuosas neutras y ácidas. Como fármaco modelo se estudió la Anfotericina B y se utilizaron como portadores manitol e inulina y como tensioactivos se ensayaron el deoxicolato de sodio (SDC) y el laurilsulfato de sodio (SLS). La difracción de rayos X reveló que el fármaco en estudio se hallaba en estado amorfo en todas las dispersiones sólidas estudiadas. Se puede concluir que la velocidad de disolución del fármaco se incrementa significativamente en presencia de portador y tensioactivo.
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Stewart, Luisa. "Physico-chemical investigations of cationic liposome/DNA complexes." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314374.
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Abogrean, Elhadi. "Physico-chemical parameters of wet deposition in Cardiff." Thesis, Cardiff Metropolitan University, 2008. http://hdl.handle.net/10369/868.
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The issue of acid deposition and associated environmental problems has received special attention during recent decades and has been the subject of extensive research in a number of countries. However, there are no recent studies on acid deposition in Cardiff. Weekly rainfall samples were obtained from two urban areas in Cardiff from February 2006 to July 2007 and analysed for pH, electrical conductivity and major ions; SO42−, NO3−, Cl−, Ca2+, Na+, Mg2+, K+ and Pb2+. The chemical composition of precipitation was analysed in conjunction with meteorological variables to evaluate temporal and seasonal variations. Annual wet deposition was estimated, and enrichment factors determined. The pH of individual precipitations fluctuated excessively with a wide range from 4.9 to 6.6 indicating high variability in the acid sources and in neutralisation processes. Correlations between calcium and sulphate imply that CaSO4 may merge with the rainfall and neutralise the acidity. The volume-weighted mean concentrations of NO3− and non-sea salt SO42− were 24.1 and 31.4 μeq l−1, respectively. With the exception of the sea salt ions, no distinct spatial variations in ion composition were observed. Enrichment factors were calculated for most ions and higher correlation coefficients were obtained among most of the ions. Sea-derived material (Na+, Mg2+ and Cl−) showed pronounced cycles in concentration with maxima in autumn/winter. The Cl- (102 kg ha-1 yr-1) and Na+ (66 kg ha-1 yr-1) showed the highest wet deposition flux compared to the other ions. Anthropogenic and crustal sources made a significant contribution to both the acidification and neutralisation of precipitation in Cardiff. In all rain samples SO4-2 concentration exceeded NO3- concentration. Statistical analysis showed no significant differences in the physico-chemical parameters of the rainfall samples between the sites when tested at p<0.05. However, the ionic concentrations of wet precipitation depicted significant seasonal differences except for rainfall volume, K+, NO3- and SO4-2
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Mason, G. "Preparation and physico-chemical studies of composite carbons." Thesis, University of Salford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381856.
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Ayoola, Yetunde Adejonwo. "Physico-chemical changes of carbohydrates during heat processing." Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254185.
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Johnson, Fiona Ann. "The physico-chemical characterisation of alginate raft systems." Thesis, University College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297175.
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Slater, Christine. "Physico-chemical aspects of aqueous gloss emulsion paints." Thesis, Loughborough University, 1987. https://dspace.lboro.ac.uk/2134/13747.
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The formulation of an aqueous paint involves the mixing of a very complex chemical system. The objective of this study was to investigate the colloidal and surface properties of this type of system. From this an overall picture of the physico-chemical interactions occurring between the pigment and polymer, and the effect of the soluble components, could be obtained. By a greater appreciation of the basic chemistry of the paint system, improvements of the final commercial products cculd be possible. A simple paint system was designed which contained industrial pigment, poly(vinylacetate) polymer and soluble ccnstituents including sodium hexametaphosphate (dispersant), and sodium dodecylsulphate (emulsifier). A non ionic thickener, sodium hydroxyethylcellulose, and an ionic thickener, carboxymethyl cellulose was also included. The effect of the alumina coating was investigated by testing both alumina coated pigment, RTC90, uncoated ccnventional rutile, RD rutile and alumina pigment, Hydral. The effect of these soluble aluminium species on the pclymer was also demonstrated. The interaction of the soluble components on the polymer and pigment WoS investigated using microelectrophoresis and adsorption techniques. The distribution of mcbilities in colloidal samples was obtained for both coated and uncoated pigments in a variety of solutes. The effect of thickener concentration on paint formulations and millbases was measured at constant temperature in precision bore glass columns. The data was analysed using an interactive computer programme based on the work of Carstensen & Su (1970a 1970b). The effect of thickener with respect to flocculation, film formation and gloss was also estimated using optical and infrared techniques. This study has given an idea of the complexity of paint formulations and the need for further model studies on the individual components of the system.
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Glicerina, Virginia Teresa <1979>. "Physico-chemical and microstructural properties of food dispersions." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6412/1/Glicerina_Virginia_tesi.pdf.
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The macroscopic properties of oily food dispersions, such as rheology, mechanical strength, sensory attributes (e.g. mouth feel, texture and even flavour release) and as well as engineering properties are strongly determined by their microstructure, that is considered a key parameter in the understanding of the foods behaviour . In particular the rheological properties of these matrices are largely influenced by their processing techniques, particle size distribution and composition of ingredients. During chocolate manufacturing, mixtures of sugar, cocoa and fat are heated, cooled, pressurized and refined. These steps not only affect particle size reduction, but also break agglomerates and distribute lipid and lecithin-coated particles through the continuous phase, this considerably modify the microstructure of final chocolate. The interactions between the suspended particles and the continuous phase provide information about the existing network and consequently can be associated to the properties and characteristics of the final dispersions. Moreover since the macroscopic properties of food materials, are strongly determined by their microstructure, the evaluation and study of the microstructural characteristics, can be very important for a through understanding of the food matrices characteristics and to get detailed information on their complexity.
The aim of this study was investigate the influence of formulation and each process step on the microstructural properties of: chocolate type model systems, dark milk and white chocolate types, and cocoa creams. At the same time the relationships between microstructural changes and the resulting physico-chemical properties of: chocolate type dispersions model systems dark milk and white chocolate were investigated.Le proprietà macroscopiche di dispersioni alimentari a base oleosa tra cui quelle reologiche, meccaniche e sensoriali (consistenza, texture, palatabilità, viscosità, stabilità fisica, ecc.) sono fortemente influenzate dalla loro microstruttura che è considerata un parametro chiave nella comprensione del “comportamento macroscopico” degli alimenti. In particolar modo le proprietà reologiche di tali matrici alimentari sono direttamente influenzate sia dalla formulazione che dal processo di produzione. Durante la produzione di cioccolato e/o surrogati a base di cacao, miscele di zucchero, cacao e grassi vengono riscaldate, raffreddate, pressurizzate e raffinate (Beckett 2000). Questi operazioni tecnologiche la contribuiscono a ridurre la dimensione delle particelle, a rompere gli agglomerati e a distribuire grassi e lecitina attorno alle singole particelle, modificandone la loro microstruttura . Poiché le proprietà macroscopiche di tali matrici alimentari sono fortemente determinate dalla loro microstruttura, la valutazione delle caratteristiche microstrutturali risulta essere molto importante al fine di studiare e ottenere dettagliate informazioni sulla loro complessità. Il presente studio si è proposto pertanto di valutare, mediante tecniche dirette di microscopia ed indirette di laser light diffraction, l’influenza delle diverse formulazioni e di ogni singola fase del processo produttivo sulle proprietà microstrutturali di: sistemi modello a base oleosa, cioccolato fondente, al latte e bianco e surrogati a base di cacao. Parallelamente sono state investigate le relazioni esistenti tra le caratteristiche micro strutturali delle suddette matrici e le loro proprietà reologiche e chimico-fisiche.
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Glicerina, Virginia Teresa <1979>. "Physico-chemical and microstructural properties of food dispersions." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amsdottorato.unibo.it/6412/.
Full textAbstract:
The macroscopic properties of oily food dispersions, such as rheology, mechanical strength, sensory attributes (e.g. mouth feel, texture and even flavour release) and as well as engineering properties are strongly determined by their microstructure, that is considered a key parameter in the understanding of the foods behaviour . In particular the rheological properties of these matrices are largely influenced by their processing techniques, particle size distribution and composition of ingredients. During chocolate manufacturing, mixtures of sugar, cocoa and fat are heated, cooled, pressurized and refined. These steps not only affect particle size reduction, but also break agglomerates and distribute lipid and lecithin-coated particles through the continuous phase, this considerably modify the microstructure of final chocolate. The interactions between the suspended particles and the continuous phase provide information about the existing network and consequently can be associated to the properties and characteristics of the final dispersions. Moreover since the macroscopic properties of food materials, are strongly determined by their microstructure, the evaluation and study of the microstructural characteristics, can be very important for a through understanding of the food matrices characteristics and to get detailed information on their complexity.
The aim of this study was investigate the influence of formulation and each process step on the microstructural properties of: chocolate type model systems, dark milk and white chocolate types, and cocoa creams. At the same time the relationships between microstructural changes and the resulting physico-chemical properties of: chocolate type dispersions model systems dark milk and white chocolate were investigated.Le proprietà macroscopiche di dispersioni alimentari a base oleosa tra cui quelle reologiche, meccaniche e sensoriali (consistenza, texture, palatabilità, viscosità, stabilità fisica, ecc.) sono fortemente influenzate dalla loro microstruttura che è considerata un parametro chiave nella comprensione del “comportamento macroscopico” degli alimenti. In particolar modo le proprietà reologiche di tali matrici alimentari sono direttamente influenzate sia dalla formulazione che dal processo di produzione. Durante la produzione di cioccolato e/o surrogati a base di cacao, miscele di zucchero, cacao e grassi vengono riscaldate, raffreddate, pressurizzate e raffinate (Beckett 2000). Questi operazioni tecnologiche la contribuiscono a ridurre la dimensione delle particelle, a rompere gli agglomerati e a distribuire grassi e lecitina attorno alle singole particelle, modificandone la loro microstruttura . Poiché le proprietà macroscopiche di tali matrici alimentari sono fortemente determinate dalla loro microstruttura, la valutazione delle caratteristiche microstrutturali risulta essere molto importante al fine di studiare e ottenere dettagliate informazioni sulla loro complessità. Il presente studio si è proposto pertanto di valutare, mediante tecniche dirette di microscopia ed indirette di laser light diffraction, l’influenza delle diverse formulazioni e di ogni singola fase del processo produttivo sulle proprietà microstrutturali di: sistemi modello a base oleosa, cioccolato fondente, al latte e bianco e surrogati a base di cacao. Parallelamente sono state investigate le relazioni esistenti tra le caratteristiche micro strutturali delle suddette matrici e le loro proprietà reologiche e chimico-fisiche.
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MANCINI, ALESSANDRO. "Physico-Chemical Characterization of Emissions from Braking Operation." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2023. https://hdl.handle.net/10281/402444.
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La tesi esplora le correlazioni fra composizione chimica del particolato emesso in frenata e alcuni fattori quali: i) le combinazioni di materiali che compongono l'interfaccia tribologica; ii) le condizioni di guida; iii) le frazioni dimensionali in cui vengono prodotti i particolatiThis thesis reports on the correlations between the compositional features of the particulates produced by brakes and several determining or modulating factors, such as: i) The starting material composing the friction couple; ii) the driving conditions; and iii) the dimensional fractions in which the particulates are generated and emitted.
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Mirajkar, S. P. "Hydrothermal synthesis, physico- chemical characterization of omega zeolite." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1996. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2850.
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Gore, K. U. "Structural determination and physico chemical studies of zeolites." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2001. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2310.
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Kaselowski, Tanja. "Physico-chemical and microalgal characteristics of the Goukamma Estuary." Thesis, Nelson Mandela Metropolitan University, 2012. http://hdl.handle.net/10948/d1011130.
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Estuaries are intrinsically complex and dynamic ecosystems that display marked spatial and temporal variability. Because estuaries are situated at the receiving end of catchment activities, they are at particular risk of alterations to their natural complexity. The overarching objective of this study was to gain an overview of the abiotic conditions and biotic response of the Goukamma Estuary, a small temporarily open/closed estuary (TOCE) which is situated in a relatively undisturbed catchment in the Southern Cape. Physico-chemical properties drive estuarine ecology, and together with biological indicators, are commonly assessed to determine the present status of an estuary. During the study, physico-chemical parameters reflected great spatial and temporal variability in response to the mouth state over a 13 month period. Parameters ranged within expected limits, as proposed by the conceptual model for water quality of TOCE’s (Snow and Taljaard 2007). Of particular importance was the prominent occurrence of salinity stratification and hypoxic conditions (dissolved oxygen [DO] < 3 mg l-1) during both open and closed mouth states. Data indicated that in the wide and shallow lower reaches, weak stratification gradients were present and oxygenated conditions (DO > 6 mg l-1) were maintained throughout the water column mainly by wind and tidal action. However, stratification increased towards the deeper, channel-like middle and upper reaches of the estuary, followed by a significant reduction in bottom DO concentrations and development of hypoxia and anoxia. Bottom water hypoxia commonly occurs in microtidal estuaries due to the limited influence of mixing forces, mainly by wind and tidal action. The Goukamma Estuary is a channel-like microtidal estuary where stratification effectively limited oxygenation of the bottom water which resulted in frequent occurrence of bottom water hypoxia. During June 2010 when the highest local rainfall (75 mm) was recorded for the region, salinity and DO data showed that this amount of rainfall was insignificant as it did not replenish the water column of oxygen. Only the surface 0.5 m layer was fresh and oxygenated while below this, the water column was completely hypoxic. In an unimpacted state, the Goukamma Estuary is a blackwater system and is expected to be nutrient poor; however, farming activities in the catchment have resulted in elevated nutrient concentrations. This study showed that significantly higher nutrient concentrations were measured in the middle and upper reaches of the estuary, adjacent to cattle farms situated in the floodplain of these reaches. Nutrient concentrations represented mesotrophic (dissolved inorganic nitrogen [DIN] > 500 μg l-1) to eutrophic conditions (dissolved inorganic phosphorus [DIP] > 25 μg l-1). Nutrient input stimulated phytoplankton to attain a significantly high biomass, ranging between 0.3 – 112 μg l-1 (~ 7.7 ± 1.3 μg l-1; n = 128) and 0.8 – 289 μg l-1 (~ 21.1 ± 4.4 μg l-1; n = 80) during the open and closed states, respectively. High organic loads are associated with high oxygen demands which consequently result in hypoxia following decomposition. Exacerbated by natural salinity stratification which effectively limits oxygenation of the water column, unnaturally high nutrient concentrations and coinciding organic loads place the estuary at particular risk of degradation. This study captured key patterns and processes by quantifying salinity, oxygen and nutrient concentrations in addition to biological indicators (phytoplankton biomass and community composition). Considering possible budget constraints, it is recommended that monthly salinity and oxygen concentrations should be monitored as well as seasonal nutrient concentrations. It is also recommended that riparian buffer zones should be established in the middle and upper reaches of the estuary, as these vegetation buffers have been well documented to contribute to nutrient attenuation and improved water quality from agricultural run-off.
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Graf, Anja, and n/a. "Preparation and physico-chemical characterisation of microemulsion-based nanoparticles." University of Otago. School of Pharmacy, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080701.121440.
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Purpose: The purpose of this study was to investigate possible effects of different microemulsion structure-types and types of monomer used on the formation of poly(alkylcyanoacrylate) nanoparticles, the entrapment into and release of insulin from these formulations as well as the bioactivity of the insulin upon intragastric delivery of the insulin-loaded nanoparticles dispersed in the microemulsion template.
Methods: For two different microemulsion systems consisting of water, isopropyl myristate and either sugar-based surfactants or a macrogol glyceride-based surfactant-mixture, pseudo-ternary phase diagrams were established. Microemulsion samples therein were identified and characterised with polarising light microscopy, viscosity and conductivity measurements, differential scanning calorimetry, cryo-field emission scanning electron microscopy and self-diffusion nuclear magnetic resonance to determine the microemulsion structure-type. Nanoparticles were prepared from various microemulsion templates by interfacial polymerisation using ethyl (2) cyanoacrylate and butyl (2) cyanoacrylate. Particle size distribution and surface charge were measured using photon correlation spectroscopy and electrophoretic mobility. The morphology of the particles was characterised by scanning and transmission electron microscopy. Insulin was used as a model protein and the amount entrapped into and released from the particles was determined using a reverse phase HPLC assay. A diabetic rat model was employed to examine the bioactivity of different nanoparticle-microemulsion formulations with blood glucose and serum insulin as parameters measured by a proprietary glucometer and enzyme-linked immunosorbent assays, respectively.
Results: The microemulsion system based on sugar-surfactants only formed solution-type microemulsions which could not all satisfactorily be used as a polymerisation template in the presence of insulin. The system however also showed an environmentally responsive gelling behaviour which may be suitable for depot delivery. The macrogol glyceride-based microemulsion system resulted in microemulsions with a continuous transition from water-in-oil to oil-in-water droplet-types via the bicontinuous structure-type. Microemulsion samples of each structure-type could serve as nanoparticle templates and resulted in particles with similar properties. Entrapment efficiency of insulin into the nanoparticles was template and monomer dependent. However, insulin was found to interfere with the polymerisation leading to a high variability in entrapment and release kinetics of these drug delivery systems. The degree of interference depended on the type of monomer and the size of the aqueous pseudo-phase of the microemulsion template. The interpretation of the results was further complicated by a possible competitive polymerisation initiation of insulin with the surfactant-mixture. Upon intragastric administration of the insulin-loaded nanoparticles dispersed in the oil-in-water microemulsion template a significant reduction in blood glucose could be achieved for up to 30 hours. However, no significant serum insulin concentration was detectable.
Conclusions: Structurally different microemulsion templates resulting in nanoparticles with similar properties may offer increased formulation flexibility, in that a microemulsion template can be chosen which best solubilises the drug. Thus the microemulsions investigated in this thesis may serve as nanoparticle templates for designing entrapment processes for peptides and proteins with a simple one-step preparation by interfacial polymerisation. However, only if one was able to optimise and control the factors leading to the high entrapment and release variability these nanoparticles on the basis of microemulsions might be promising carriers for the oral delivery of peptide and protein bioactives.
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Imafidon, Gilbert Idolo. "Genetic polymorphism and physico-chemical properties of milk proteins." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74578.
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The properties of genetic variants of $ alpha sb{ rm s1}$-casein (BB, AB), $ beta$-casein (A$ sp1$A$ sp1$, A$ sp2$A$ sp2$, A$ sp1$A$ sp2$, A$ sp1$A$ sp3$, A$ sp2$A$ sp3$, A$ sp1$B, A$ sp2$B, BB), $ kappa$-cn (AA, AB, BB) and $ beta$-lactoglobulin (AA, AB, BB) were compared. The caseins and $ beta$-lactoglobulin were purified by mass ion exchange chomatography. Model systems of $ alpha sb{ rm s1}$- and $ kappa$-caseins were compared with respect to their stability towards calcium ions and other major milk salts precipitation. $ beta$-Casein, $ alpha sb{ rm s1}$-casein BB + $ beta$-caseins and $ kappa$-casein were also compared in their ability to resist calcium ion precipitation. $ kappa$-casein AB was a better stabilizer of $ alpha sb{ rm s1}$-casein than the BB and AA variants. $ alpha sb{ rm s1}$-Casein BB resisted calcium ion precipitation more than the AB variant in presence of $ alpha$-lactose, citrate, chloride and magnesium ions. $ kappa$-Casein BB stabilized $ alpha sb{ rm s1}$-casein AB more than the BB variant in presence of calcium and phosphate ions. Solubility of $ kappa$-casein AA, however, was greater than that of $ kappa$-cn BB and $ kappa$-cn AB variants in calcium and phosphate solutions. As in $ alpha sb{ rm s1}$-casein, significant differences were also found among $ kappa$-casein variants in stabilizing $ beta$-casein against calcium ion precipitation. $ beta$-Caseins A$ sp1$A$ sp1$, A$ sp2$A$ sp2$ and A$ sp1$B produced the most stable micelles while those of A$ sp2$B and B variants the least at 0.03-0.25 $ kappa$-cn/$ beta$-casein ratios and 20 mM Ca$ sp{2+}$. However, stability of micelles formed from $ alpha sb{ rm s1}$-cn + $ beta$-cn A$ sp2$A$ sp3$, $ alpha sb{ rm s1}$-cn + $ beta$-cn A$ sp1$A$ sp3$, and $ alpha sb{ rm s1}$-cn + $ beta$-cn A$ sp2$A$ sp2$ caseins were higher than those of $ alpha sb{ rm s1}$-cn + $ beta$-cn A$ sp1$A$ sp2$, $ alpha sb{ rm s1}$-cn + $ beta$-cn A$ sp1$B and $ alpha sb{ rm s1}$-cn + $ beta$-cn A$ sp1$A$ sp1$.
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Swales, Darren Keith. "Physico-chemical aspects of rosin emulsion sizing of paper." Thesis, Loughborough University, 1992. https://dspace.lboro.ac.uk/2134/12429.
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A study has been made on the mechanism of rosin sizing in papermaking. By using microelectrophoresis and laboratory prepared handsheets, a study of the effect of pH, certain metal salts, and various physical parameters on the overall electrokinetics and sizing efficiency of the system has been made. By the use of a novel sizing method it was possible to effectively size handsheets in the alkaline pH range, which had previously not been possible when using rosin dispersion sizes. This permitted the inclusion of calcium carbonate as a filler, which has particular advantages in the finished paper. Use of the theory proposed by Derjaguin-Landau-Verwey and Overbeek on colloidal interaction, made it possible to explain and predict the likely outcome of sizing experiments, by analysing the electrokinetics of the system components. A comparative study on the effect of rosin fortification and the stabilisation of the dispersions by the use of casein has been made. From the results obtained, fortification leads to an improvement in sizing, particularly if the drying of the paper is not very efficient. Whereas the interactions of casein primarily effect the stabilisation of the dispersion, protein desorption from the solid-liquid interface causes initial flocculation of the dispersion. If the desorption is kept to a minimum, the dispersion is still stable and an effective sizing agent.
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Wang, Qi. "Physico-chemical characterisation of water soluble non-starch polysaccharides." Thesis, King's College London (University of London), 1998. https://kclpure.kcl.ac.uk/portal/en/theses/physicochemical-characterisation-of-water-soluble-nonstarch-polysaccharides(0802c1fd-9a51-4f9f-b608-5b7343c605a2).html.
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This thesis is concerned with the development of physico-chemical techniques to characterise the properties of water soluble non-starch polysaccharides (s-NSP). The first part of this project was to characterise the structure and solution properties of s- NSP extracted from a plant, Detarium senegalense Gmelin. The extracted s-NSP was analysed by GLC and found to be similar in structure to tamarind xyloglucan. This was confirmed by comparing the oligosaccharides released on enzymatic digestion with those obtained from tamarind xyloglucan. Histochernical examination of detariurn seed showed the presence of xyloglucan in highly thickened cell walls. The intrinsic viscosity of detariurn gum was found to be high, indicating that the sample was of high molecular weight. The semi-dilute solution characteristics investigated by steady and dynamic shear rheometry, suggest that detarium gum is a well behaved linear polymer entanglement system. Static light scattering was also successfully applied to examine the molecular weight and architecture of the detarium xyloglucan macromolecules. The physiological behaviour of s-NSP when consumed is critically dependent on their physico-chemicapl roperties,i ncluding the rate and degreeo f hydration. In the second part of the project a method for determining the hydration rate of a powdered form of s- NSP was developed. A logarithmic model for describing the hydration kinetics of guar gum was also establishedT. his model was used to investigatet he effects of polymer concentration (C), molecular weight (M), and particle size on the hydration rate of guar gum. The results showed that there was a significant inverse relationship between hydration rate and M and mean particle size, respectively. The hydration rate increased with increasingC at a low concentrationr ange,b ut decreasedw hen C>1.2% (w/w). The pH in the lumen of the gastrointestinal tract of human is acidic, usually between 2.0 and 1.5 after a meal. The stability of guar gum in acidic conditions was investigated at temperatures 25,37 and 50'C. The results indicated that there was unlikely to be significant acidic degradation of guar gum in the human gastrointes final tract. The pH condition was also found to influence the hydration rate of guar gum. In general, the hydration rate was lower in an acid environment than it was in neutral conditions
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Hodgson, Mike. "Aroma release and delivery : physiological and physico-chemical considerations." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417106.
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Olugbenga, F. S. "Synthesis and physico-chemical studies on conjugated heteroenoid compounds." Thesis, Cardiff University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332625.
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Ismail, Baraem. "Dates : physico-chemical characteristics, total quality and nutritional significance." Thesis, University of Central Lancashire, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.275924.
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Thanos, A. J. "Physico-chemical changes in vegetables during processing and storage." Thesis, University of Reading, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373525.
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Carthew, David Leonard. "Physico-chemical properties of poloxamer surfactants related to adsorption." Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243418.
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Jazdzyk, Mikaël. "Physico-chemical studies of fullerene derivatives and related systems." Thesis, University of Exeter, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272983.
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Liu, Bing-Lan. "Physico-chemical studies on cellobiose oxidase from Phanerochaete chrysosporium." Thesis, University of Essex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261161.
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Kay, Michael Andrew. "Physico-chemical mechanisms of fault sealing : an experimental study." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/12334.
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This thesis presents the background, methodology, and results of an experimental study of the roles of stress, fault zone micro-structure, and environmental conditions on fault sealing. Synthetic fault gouges were tested in a suite of controlled experiments designed to elucidate the effects of a range of physical, structural, and chemical parameters on gouge reactivity. The experiments began with a series of ‘batch’ tests, designed to calibrate the purely chemical reactions. These were followed by a series of hydrostatic and non-hydrostatic pressure tests, designed to investigate the effect of burial depth and tectonic stress (confining pressure and deviatoric stress). The latter suites of experiments were conducted using a new experimental rig, designed and built specifically for this study. Each experiment used either a controlled size fraction, or a bulk mixture of particle sizes produced by crushing a rock sample to form a synthetic gouge. Highly reactive ultra-fine particles were removed to allow more accurate measurement of gouge surface area and hence reaction rates. Dissolution and precipitation rates were determined for each experiment by analysing dissolved silica concentrations of the pore fluids, using High Performance Liquid Chromatography, and applying them to a kinetic model. The non-hydrostatic tests also employed new apparatus that allowed the simultaneous measurement of fault-normal permeability and compaction throughout each experiment. The observed reaction rates have a strong dependence on temperature, particle size distribution, and pressure, in decreasing order of influence. This is consistent with field observations from a range of hydrocarbon reservoir rocks around the world. Theoretically, the finer particles would be expected to have higher specific surface energies and greater total reactive surface areas, and hence faster reaction rates. This has been confirmed by the results.
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Dicks, Reay Gary. "Microalgae flocculation and sedimentation by physico-chemical property exploitation." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/10366.
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The purpose of this research was to characterise the physical properties of microalgae, as a function of growth and suspension conditions, to enable exploitation of these characteristics for improved separation whilst allowing for water recycle.
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Armstrong, Jonathan Keith. "Physico-chemical studies of block copolymers in aqueous solution." Thesis, University of Greenwich, 1997. http://gala.gre.ac.uk/9544/.
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The dilute aqueous solution behaviour of oxyethylene/oxypropylene copolymers has been investigated as a function of temperature (275-370K), copolymer concentration (0.1-5% w/v) and copolymer composition [polyoxypropylene (POP) and polyoxyethylene (POE) homopolymers (750-4000gmol-1 ) and diblock copolymers (3450-13300gmol-1 ), poloxamers (POE-POP-POE triblock copolymers, 1100-14000gmol-1 ) and poloxamines (ethylene diamine alkoxylates, 1650-26000gmol-1 )] using the macroscopic techniques of high sensitivity differential scanning calorimetry (HSDSC), and differential scanning densitometry (DSD) and also using the technique of 1H and 13C-NMR. The observed phase transitions from HSDSC data are indicative of an aggregation process and are consequent upon changes associated with POP involving dehydration, a conformational change and aggregation. For POP homopolymers, the phase transition results in phase separation of the polymer (cloud point) but for the diblock copolymers, poloxamers and poloxamines these copolymers remain in solution due to the effects of the POE portion of the copolymer. The phase transition temperature (Tm ) decreases and the calorimetric enthalpy (AHcai) increases with increasing molecular mass of the POP block and show no relationship to the POE content. DSD data of poloxamers in water at a concentration of 1 % (w/v) show a sharp increase in partial specific volume (v) with increasing temperature, the mid-point of the transition in agreement with the Tm observed by HSDSC. The partial specific volume change (Av) approach zero as the POE:POP ratio approaches 1:0 indicative that the phase transition is associated with changes in the POP portion of the copolymer. TI relaxation NMR data for poloxamer 237 in D20 as a function of temperature shows a gradual increase in relaxation times for -CH2- and -CH(Me)-resonances with increasing temperature due to increased molecular motion, but a sharp decrease of the -CH(Me)- relaxation time was observed at the Tm relating to a change in conformation of the POP portion of the copolymer. The effects of cosolutes (NaCl, Na2HPO4/NaH2PO4, urea and guanidinium chloride) and cosolvents (methanol, ethanol, n-propanol, n-butanol and formamide) on the observed phase transition of poloxamers have been investigated using HSDSC. Sodium chloride, phosphate buffer, n-propanol and n-butanol favour aggregation of the copolymer reflected in a lowering the Tm and an increase in AHcal. Conversely, urea, guanidinium chloride, methanol, ethanol and formamide prevent the onset of aggregation reflected in an increase in Tm and a lowering of AHcai. The effects of cosolutes and cosolvents on the aggregation behaviour of poloxamers are explained in terms of enhancing or breaking water structure or by possibly replacing water molecules in the solvation sphere of the POP portion of the copolymer. The calorimetric output has been analysed using a model fitting procedure based upon a mass action description to obtain estimates for thermodynamic parameters which characterise the aggregation process. These important parameters include T½, the temperature at which the aggregation process is half completed, AHcal, AHvH . the van't Hoff enthalpy and n the aggregation number. The modelled excess heat capacity data are in good agreement with the experimental calorimetric outputs. An enthalpy-entropy compensation plot for all data obtained indicate that the solvent-solute interactions that are responsible for the phase transitions observed by HSDSC are the same for all of the copolymers investigated regardless of the copolymer composition and concentration.
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Brunelli, Andrea <1984>. "Advanced physico-chemical characterization of engineered nanomaterials in nanotoxicology." Doctoral thesis, Università Ca' Foscari Venezia, 2013. http://hdl.handle.net/10579/4656.
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L'ampio utilizzo di nanomateriali ingegnerizzati (ENM) in svariati prodotti sta suscitando una crescente attenzione sull potenziale rischio di ENM nei confronti della salute umana e l'ambiente. Nonostante le indagini tossicologiche fin qui condotte, solo in poche di esse è stata condotta la caratterizzazione di ENM prima, durante e dopo i test tossicologici. In questa tesi, all’interno del progetto europeo EU-FP7 (ENPRA) e nazionale (PRIN 2009), è stata effettuata una caratterizzazione completa di alcuni più diffusi ENM (i.e. n-TiO2, n-ZnO, n-Ag e MWCNT). In primo luogo, sono stati aggiornati i dati di caratterizzazione primaria con ulteriori analisi; inoltre, è stata effettuata la caratterizzazione secondaria di ENM, indagando il loro comportamento in matrici ambientali. I risultati ottenuti mostrano che la stabilità di ENM è stata principalmente influenzata da agenti stabilizzanti (in mezzi biologici) e dalla concentrazione iniziale di ENM (in acque sia artificiali e reali). Inoltre, la biodistribuzione di ENM negli organi studiati è stata maggiormente influenzata dalla composizione chimica e dimensione delle particelle indagate. Sono discussi sia l'approccio di caratterizzazione proposto che l'implicazione dei risultati ottenuti.The extensive use of engineered nanomaterials (ENM) in both industrial and consumer products is triggering a growing attention on the potential risk of ENM posed to human health and the environment. Despite the intensive toxicological investigations, both in vitro and in vivo, only few of them have embedded a solid characterization approach, including the study of ENM before, during and after toxicological testing. Within EU-FP7 (ENPRA) and national (Toxicological and environmental behaviour of nano-sized titanium dioxide) projects activities, a comprehensive characterization of both inorganic (n-TiO2, n-ZnO, n-Ag) and organic (multiwalled carbon nanotubes, MWCNT) ENM was carried out, updating and adding primary characterization data, investigating particle size, shape, crystallite size, crystalline phases, specific surface area, pore volume as well as inorganic impurities of concern. Electron microscopy, X-ray diffraction, BET method and Inductively coupled plasma- mass spectrometry or optical spectroscopy were the employed techniques. With regard to the secondary characterization of ENM, the study was divided in: (a) assessing the engineered nanoparticles (ENP) behavior in biological (0.256 mg ENP/ml) as well as in real and synthetic waters (environmentally realistic concentrations: 0.01, 0.1, 1 and 10 mg n-TiO2 P25/l) over different time interval (24 h in biological media instead of 50 h in water media) to mimic duration of toxicological tests, by means of Dynamic Light Scattering (DLS), analytical centrifugation and nephelometry; (b) evaluating the ENM biodistribution in a secondary target organ (i.e. mice brain) after intratracheally instillation of ENM (0, 1, 4, 8, 16, 32, 64 and 128 ug ENM/animal tested), achieved by a microwave-assisted digestion method, followed by ICP-MS analysis, after selecting inorganic elements (i.e. Ti, Zn, Ag, Al and Co) as tracers of ENM presence in biological tissues. To investigate the ENP behavior in biological media and ENM biodistribution in mice, both dispersion protocols of the selected ENP and analytical protocols for ENM detection after toxicological testing were provided. The study of ENP stability in biological media highlighted that the fetal bovine serum (FBS) is the main parameter affected the ENP behavior. Among biological media tested, the largest size distributions, immediately after sample preparation, were irecorded for n-TiO2 NRCWE-003 dispersions. n-ZnO NM-111 dispersions were the most stable (12% average demixing, simulating 24 h of real sedimentation), except for Ag NM-300, originally received as dispersion (<1% average demixing). As expected, the ENP sedimentation rates investigated in the biological medium without any stabilizer (i.e. RPMI), were the highest for the whole set of ENP tested. In general, the highest sedimentation rates were recorded for n-TiO2 NM-101 and n-Ag 47MN-03 dispersions (51% average demixing, simulating 24 h of real sedimentation). The study of the n-TiO2 P25 stability in waters showed that agglomeration and sedimentation of n-TiO2 were mainly affected by the initial concentration. Sedimentation data fitted satisfactorily (R2 average: 0.90; 0.74
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GENNARO, MARIA ELENA. "STUDY OF PHYSICO-CHEMICAL PARAMETERS CHARACTERIZING NAPHTHENIC ACID CORROSION." Doctoral thesis, Università degli Studi di Milano, 2013. http://hdl.handle.net/2434/214983.
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The recent increase in crude oil cost arose interest in cheaper oils, usually called “opportunity crudes”. These oils are difficult to transport and treat, mainly because of their sulphur content, acidity and high density, but their cheap price makes them attractive, because refineries capable of processing them could gain a higher profit. Opportunity crudes composition affects process parameters and they can also cause corrosion and failures in plant equipment.
It is well known that the main corrosive agents are the naphthenic acids (NAs), but the mechanism is complex and very little is known about it since there are many factors affecting it such as type of acids, temperature, sulphur compounds and fluid velocity.
Thus damage process has not been clarified yet and at this time there is no accurate model available for predicting crude oil corrosiveness.
Though considerable work has been done to understand NA corrosion in refineries, it turned out to be unsuccessful when the interdependence of NAs type and corrosion effects is considered.
The objective of the research activity was to get more insight into the relationships between physico-chemical properties of crude oils and corrosion, in order to build a model aimed at identification of a corrosivity index which might help operators to determine the aggressiveness of processed fluids.
For this purpose an analytical protocol was identified in order to determine the main molecular characteristics, such as number of carbon atoms, rings and average molecular weight. After some preliminary high temperature and pressure tests, a new equipment was developed and designed capable of reproducing real plant conditions. The small-scale plant was first used with a reference fluid consisting of gasoil and a commercial mixture of NAs, and then tested with actual crudes. The use of experimental design and of proper analytical techniques allowed to build a model for the corrosion of two different materials.
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Chakraborty, Subrata. "Physico-Chemical studies on micellar properties of selected amphiphiles." Thesis, University of North Bengal, 2015. http://ir.nbu.ac.in/handle/123456789/1527.
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Medini, Federico. "Physico-chemical characterization of a surface barrier discharge plasma source." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Find full textAbstract:
Cold Atmospheric pressure Plasmas (CAP) generated by Dielectric Barrier Discharges (DBDs) are being studied and developed for an ever-widening range of applications in both biomedical and industrial areas.
In particular surface DBDs (SDBDs), consisting of a planar powered electrode separated from a grounded mesh by a thin dielectric layer, have been gaining great interest for their ability to produce highly reactive atmospheres at close-to-environmental temperature and almost independent from the electrical properties of the target, which is treated in the afterglow of the surface plasma.
The active chemistry initiated in the afterglow of SDBDs operated in air is characterized by the presence of long-lived reactive oxygen and nitrogen species such as O3, NOx and HNOx, which are recognized to play an important role in many industrial and biomedical applications based on the use of the plasma afterglow.
Knowing the kinetics of all the chemical species produced in the plasma and in its afterglow is then fundamental to control and optimize the processes for which SDBDs are being used.
This project focuses on the physico-chemical characterization of a SDBD plasma source developed by the research group in Industrial Application of Plasmas (AIP - DIN - Alma Mater Studiorum), supplied with a high voltage AC generator with tunable frequency and duty cycle.
First a study of the surface power density (SPD) variation as a function of voltage, frequency and duty cycle was made. Then the kinetics of O3/NO2/NO3 concentrations in the plasma afterglow were studied by means of OAS measurements.
This project’s main aim is to gather additional knowledge on the kinetics of the produced reactive species, comparing the results with the ones from other works from literature, providing additional evidence about SPD being the driving parameter for plasma afteglow kinetics.
A second aim is to provide a set of data that can be used as input and validation for future modelling tools.
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Domagalski, Jakub. "Electrochemically engineered anodic alumina Nanotubes: physico-chemical properties and Applications." Doctoral thesis, Universitat Rovira i Virgili, 2021. http://hdl.handle.net/10803/671688.
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Des del seu descobriment, l'alúmina anòdica porosa s’ha utilitzat com a recobriment protector. El descobriment de la seva estructura porosa va animar els investigadors a desenvolupar nous mètodes de fabricació d'alúmina, obtenint així geometries complexes de propietats diverses.
En aquesta tesi es desenvolupen nanotubs d'alúmina anòdica (AANTs) mitjançant un procés d’anodització que es coneix com anodització per polsos. El procés consisteix a entrellaçar polsos de corrent de baixa (~6 mA/cm2) i alta (~290-390 mA/cm2) densitat. Un flux de corrent prou alt produeix un estrenyiment vertical dels porus i unions entre cel·les més febles. L'atac electroquímic selectiu i la sonicació en aigua de l'estructura resultant permeten produir col·loides de nanotubs.
El primer objectiu d'aquesta tesi és una anàlisi exhaustiva del procés per comprendre millor el mecanisme de formació dels AANTs i relacionar les condicions d’anodització amb la seva geometria resultant. El segon objectiu és avaluar i optimitzar el seu postprocessat, investigant nous mètodes d'alteració de les seves propietats fisicoquímiques. L'últim objectiu és dissenyar i fabricar nanotubs i proposar les seves aplicacions.
Aquest treball investiga l'evolució del perfil de l'alúmina en funció dels paràmetres d’anodització. A més, el corrent i el potencial del procés s'associen amb la geometria i les propietats dels nanotubs obtinguts: longitud, diàmetre intern i extern, potencial Z i tamany. En resum, un corrent més alt condueix a nanotubs més llargs i estrets amb menor càrrega superficial. S'avaluen i optimitzen les condicions de sonicació. Es demostra que el recuit a alta temperatura dels nanotubs té un impacte en la seva estructura cristal·lina i composició elemental. Posteriorment, els nanotubs es decoren electrostàticament amb nanopartícules magnètiques i es modifica el seu interior amb una proteïna marcada amb fluoròfor. Aquests col·loides magnètics han demostrat ser útils per a la detecció de la catepsina B, el que demostra la seva utilitat com a sensors.La anodización del aluminio tiene casi un siglo de historia. La alúmina anódica se utilizó inicialmente como recubrimiento protector, pero el desarrollo de la microscopía electrónica reveló la morfología porosa de este óxido. Este descubrimiento animó a los investigadores a desarrollar nuevos métodos de fabricación de la alúmina porosa, obteniendo así geometrías complejas con diversas propiedades. En esta tesis se desarrollan nanotubos de alúmina anódica (AANTs) a través de un proceso de anodización que se conoce como anodización por pulsos. El proceso consiste en entrelazar pulsos de corriente de baja (~ 6 mA / cm2) y alta (~ 290-390 mA / cm2) densidad. Un flujo de corriente suficientemente alto afecta a la formación de la estructura, resultando en un estrechamiento vertical de los poros y uniones entre celdas más débiles. El ataque electroquímico selectivo y la sonicación en agua de la estructura resultante permiten producir coloides de nanotubos. El primer objetivo de esta tesis es un análisis exhaustivo del proceso para comprender mejor el mecanismo de formación de los AANTs y conectar con precisión las condiciones de anodización con la geometría resultante de la estructura. El segundo objetivo es evaluar y optimizar su posprocesado, investigando nuevas posibilidades de alterar las propiedades fisicoquímicas de los AANT. El último objetivo es diseñar y fabricar nanotubos funcionales y proponer sus aplicaciones. Este trabajo investiga la evolución del perfil de anodización en función de las condiciones del proceso de anodización. Además, la corriente y el potencial del proceso se asocian con la geometría y las propiedades de los nanotubos obtenidos: longitud, diámetro interno y externo, potencial Z y dispersión de tamaño. En resumen, una corriente más alta conduce a nanotubos más largos y estrechos con una carga superficial más baja. Se evalúan las condiciones de sonicación proponiendo un conjunto de parámetros más óptimo. Se demuestra que el recocido a alta temperatura de los nanotubos tiene un impacto en su estructura cristalina y composición elemental: el aumento de temperatura produce una fracción cristalina más alta y disminuye su contenido de azufre. Posteriormente, los nanotubos se decoran electrostáticamente con nanopartículas de maghemita y se modifica su interior con una proteína marcada con
Most of the time since its discovery, nanoporous anodic alumina was used as a protective coating. The intrinsic property revealed by the electron microscope – porosity – encouraged researchers to investigate new methods of porous alumina fabrication, obtaining complex geometries with various properties. In this thesis, anodic alumina nanotubes (AANTs) are developed through a carefully adjusted anodization process defined as pulse anodization. The process consists of interlacing current pulses of low (~6 mA/cm2) and high (~290-390 mA/cm2) density. Sufficiently high current flow affects the formation of the structure, resulting in vertical pore narrowings and weaker cell junctions. Selective acid etching and sonication in water enables to yield colloids of nanotubes. First aim of this thesis is a thorough analysis of the process to better understand the formation mechanism of AANTs and precisely connect anodization conditions with the resultant geometry of the structure. Second goal is to evaluate and optimize post-processing investigating further possibilities to alter physio-chemical properties of AANTs. Last objective is to design and fabricate functional nanotubes and propose their applications. This work reports the evolution of the anodization profile depending on the process conditions. Further, current and potential of the process are associated with the geometry and the properties of the obtained nanotubes: length, inner and outer diameter, z-potential and size dispersity. In brief, higher current leads to longer and narrower nanotubes with lower surface charge. Sonication conditions are evaluated leading to the proposal of a more optimal set of parameters. Annealing of the nanotubes is demonstrated to impact on their crystalline structure and elemental composition: temperature increase leads to higher crystalline fraction and decrease their sulfur content. Nanotubes are later electrostatically-decorated with maghemite nanoparticles and modified inside with a fluorophore labelled protein. These magnetically responsive colloids demonstrate stimuli-responsive detection of cathepsin B, supporting its utility as a sensor.
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Lodi, Alessia. "Physico-chemical and molecular characterization of soy bread containing almond." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1158163372.
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Andersson, Patrik. "Physico-chemical characteristics and quantitative structure-activity relationships of PCBs." Doctoral thesis, Umeå University, Chemistry, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-17.
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The polychlorinated biphenyls (PCBs) comprise a group of 209 congeners varying in the number of chlorine atoms and substitution patterns. These compounds tend to be biomagnified in foodwebs and have been shown to induce an array of effects in exposed organisms. The structural characteristics of the PCBs influence their potency as well as mechanism of action. In order to assess the biological potency of these compounds a multi-step quantitative structure-activity relationship (QSAR) procedure was used in the project described in this thesis.
The ultraviolet absorption (UV) spectra were measured for all 209 PCBs, and digitised for use as physico-chemical descriptors. Interpretations of the spectra using principal component analysis (PCA) showed the number of ortho chlorine atoms and para-para substitution patterns to be significant. Additional physico-chemical descriptors were derived from semi-empirical calculations. These included various molecular energies, the ionisation potential, electron affinity, dipole moments, and the internal barrier of rotation. The internal barrier of rotation was especially useful for describing the conformation of the PCBs on a continuous scale.
In total 52 physico-chemical descriptors were compiled and analysed by PCA for the tetra- to hepta-chlorinated congeners. The structural variation within these compounds was condensed into four principal properties derived from a PCA for use as design variables in a statistical design to select congeners representative for these homologue-groups. The 20 selected PCBs have been applied to study structure-specific biochemical responses in a number of bioassays, and to study the biomagnification of the PCBs in various fish species.
QSARs were established using partial least squares projections to latent structures (PLS) for the PCBs potency to inhibit intercellular communication, activate respiratory burst, inhibit dopamine uptake in synaptic vesicles, compete with estradiol for binding to estrogen receptors, and induce cytochrome P4501A (CYP1A) related activities. By the systematic use of the designed set of PCBs the biological potency was screened over the chemical domain of the class of compounds. Further, sub-regions of highly potent PCBs were identified for each response measured. For risk assessment of the PCBs potency to induce dioxin-like activities the predicted induction potencies (PIPs) were calculated. In addition, two sets of PCBs were presented that specifically represent congeners of environmental relevance in combination with predicted potency to induce estrogenic and CYP1A related activities.
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Bergstrand, Nill. "Liposomes for Drug Delivery : from Physico-chemical Studies to Applications." Doctoral thesis, Uppsala University, Department of Physical Chemistry, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3390.
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Physico-chemical characterisation of structure and stability of liposomes intended for drug delivery is the central issue in this thesis. In addition, targeted liposomes to be used in boron neutron capture therapy (BNCT) were developed.
Lysolipids and fatty acids are products formed upon hydrolysis of PC-lipids. The aggregate structure formed upon mixing lysolipids, fatty acids and EPC were characterised by means of cryo-TEM. A relatively monodisperse population of unilamellar liposomes was detected in mixtures containing equimolar concentration of the three components.
The interactions between alternative steric stabilisers (PEO-PPO-PEO copolymers) and conventional PC-and pH-sensitive PE-liposomes were investigated. Whereas the PE-liposomes could be stabilised by the PEO-PPO-PEO copolymers, the PC-liposomes showed an enhanced permeability concomitant with the PEO-PPO-PEO adsorption.
Permeability effects induced by different PEG-stabilisers on EPC liposomes were shown to be dependent on the length of the PEG chain but also on the linkage used to connect the PEG polymer with the hydrophobic membrane anchor.
An efficient drug delivery requires, in most cases, an accumulation of the drug in the cell cytoplasm. The mechanism behind cytosolic drug delivery from pH-sensitive liposomes was investigated. The results suggest that a destabilisation of the endosome membrane, due to an incorporation of non-lamellar forming lipids, may allow the drug to be released.
Furthermore, sterically stabilised liposomes intended for targeted BNCT have been characterised and optimised concerning loading and retention of boronated drugs.
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Guo, Jing. "PHYSICO-CHEMICAL STUDIES OF THE VESICULAR GLUTAMATE TRANSPORTER 1 (VGLUT1)." The University of Montana, 2009. http://etd.lib.umt.edu/theses/available/etd-01122009-152821/.
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The vesicular glutamate transporter 1 (VGLUT1) is an important membrane protein located in glutamatergic synaptic vesicles. It is responsible for the storage and release of the excitatory neurotransmitter glutamate. VGLUT1 is a highly hydrophobic integral membrane protein with a molecular weight around 61 kD. The tertiary structure of VGLUT1 is still unknown. In our study, recombinant VGLUT1 was expressed in Pichia pastoris and purified using either a nickel chelating column or cobalt-coated Dynabeads. The HiTrapTM nickel chelating column proved to be more efficient in purification of recombinant VGLUT1 than Dynabeads. To study the physico-chemical properties and structure of VGLUT1 and advance our understanding of the membrane topology, FITC was used to modify VGLUT1 in solution. On average, 5.35 ¡À 1.10 lysines were labeled with FITC in each VGLUT1 molecule. Trypsin, endoproteinase Glu-C and Arg-C were used to digest FITC labeled VGLUT1 for mass spectrometry analysis. Mass spectrometry and other proteomics techniques were applied to identify labeled residues. Nine lysine residues were revealed to be labeled by FITC in total, among which 8 lysines (K10, K25, K140, K196, K272, K339, K378, and K507) are from native VGLUT1 and one is located at myc epitope (K569).
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Bergstrand, Nill. "Liposomes for drug delivery : from physico-chemical studies to application /." Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3390.
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Nave, Andy [Verfasser]. "Physico-chemical investigation of plasma induced deposition processes / Andy Nave." Greifswald : Universitätsbibliothek Greifswald, 2017. http://d-nb.info/1141405997/34.
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Mitchell, James. "An investigation of the physico-chemical properties of clay suspensions." Thesis, Keele University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.647445.
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