In this thesis, we mainly investigate the application of a nodal discontinuous Galerkin spectral element method (DGSEM) for simulating processes in column liquid chromatography. Additionally, we investigate the effectiveness of a total variation diminishing in the mean (TVDM) limiter in controlling spurious oscillations related to the Gibbs phenomenon. With an order-of-accuracy test, we demonstrated that our nodal DGSEM achieved and, in multiple instances, even exceeded theoretical convergence rates, especially with an increased number of elements, validating the use of high-order basis functions for achieving high-order accuracy. We also demonstrated how setup parameters could affect process outcomes, which suggests that numerical simulations can help guide the development of experimental methods since they can explore the solution space of an optimization problem much faster than experimental procedures by leveraging computational speed. Finally, we showed that the TVDM limiter successfully eliminated severe oscillations and negative concentrations near shock regions but introduced significant smearing of the shocks. These findings validate the nodal DGSEM as a highly accurate and reliable tool for detailed modeling of column liquid chromatography, which is essential for improving efficiency, yield, and product quality in biopharmaceutical manufacturing.

The research presented in this dissertation consists of two primary parts. The initial focus centered on understanding the distribution of Golgi resident glycosyltransferases between the ER and Golgi at steady-state. Retrograde trafficking of these Golgi proteins has been demonstrated experimentally mandating the existence of a dynamic equilibrium between the Golgi apparatus and ER. Our published studies also included the development of a quantitative method for analysis of data collected using fluorescent microscopy. The second part of this dissertation presents results pertaining to the quantification of a unique Golgi resident protein that cycles in the late endosome bypass pathway. Using the published method of analysis and techniques developed during the initial project, the anterograde and retrograde transport kinetics of this Golgi protein were determined and used to develop a compartmental model for pH sensitive trafficking in the bypass pathway. The spatial Golgi distribution of the protein during retrograde transport to the Golgi following endosomal exit was also investigated. This research lies at the interface of experimental cell biology and quantitative computational analysis. These experiments combined more traditional experimental biological approaches with more recent computational approaches to understanding cellular mechanisms. Additionally, development of a quantitative method of analysis validated the use of fluorescent microscopy as a quantitative tool for studying intracellular proteins. / Ph. D.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Malaria infects over 200 million individuals and leads to the death of over 600 000 people annually. Currently artemisinin combination therapy treatments are effective in treating the disease, but resistance has started to emerge in Cambodia and it is suspected in parts of Vietnam. To maintain the drive to eradicate malaria globally, a great deal of research is aimed at identifying novel prevention strategies, vaccines and antimalarial compounds. Plasmodium falciparum, the most deadly of the malaria parasites, is entirely dependent on glycolysis for ATP. Several of the enzymes within this pathway have been proposed as drug targets and studied in isolation, but the pathway as a whole has not been considered. In this study we employ a bottom up approach for drug target identification in P. falciparum glycolysis. In this thesis we present the biochemical characterisation each of the glycolytic enzymes in P. falciparum trophozoites. The kinetic rate equations, which described the kinetic behaviour of the individual enzymes, were incorporated into a kinetic model. The unfitted model was validated in its ability to predict experimentally measured steady state metabolite concentrations and fluxes as well as the experimental inhibition of the glucose transporter. The validated model provided a tool for drug target identification in P. falciparum glycolysis. Metabolic control analysis and differential control analysis identified the glucose transporter, PfHT1, as a drug target based on its high control of glycolytic flux in the parasite, but low control of flux in the host erythrocyte. This differential control makes the transporter an attractive drug target, as even if both the erythrocyte and parasite glucose transporters are inhibited to the same degree, it is expected that the parasite glycolytic flux would be inhibited to a much greater degree. To demonstrate the differential control of the glucose transporter on the flux and provide further evidence that PfHT1 is an attractive drug target, we investigated the inhibition of the glucose transporter in isolated trophozoites by cytochalasin B. We also measured the inhibition of lactate production flux by cytochalasin B in both isolated P. falciparum trophozoites as well as in erythrocytes. Our findings demonstrated that differential control analysis can be used as a tool for drug target identification and that PfHT1 is an attractive drug target. In this study the fields of biochemistry and systems biology were merged to create a detailed kinetic model of asexual P. falciparum glycolysis and identify several drug targets in the pathway. The model prediction and experimental evidence of differential flux control of the glucose transporter in the host and parasite, has highlighted PfHT1 as a drug target and also demonstrates the strength of differential control analysis in identifying drug targets within a system. The kinetic model is a valuable tool for furthering our understanding of P. falciparum glycolysis and it provides a good foundation for expansion to identify drug targets in the entire central carbon metabolism of P. falciparum. / AFRIKAANSE OPSOMMING: Malaria infekteer meer as 200 miljoen mense en veroorsaak jaarliks tot 600 000 sterftes. Tans is die artemisinien-kombinasieterapie effektief in die bestryding van die siekte, maar weerstandbiedendheid van die parasiet teen die middel blyk reeds ’n merkbare effek in Kambodja en vermoedelik ook in dele van Viëtnam te hê. Om ’n wêreldwye bestryding van malaria moontlik te maak, is ’n groot deel van die huidige navorsing gemik op die identifisering van nuwe voorkomingsstrategieë, entstowwe en malariateenmiddels. Plasmodium falciparum, die dodelikste van die malaria-parasiete, is geheel en al afhanklik van glikolise vir ATP vorming. Verskeie van die ensieme in hierdie metaboliese pad is as teenmiddelteikens voorgestel, en in isolasie bestudeer, maar die pad as ’n geheel is nie bestudeer nie. In hierdie studie het ons ’n ’bottom-up’ benadering vir teenmiddel teikenidentifisering in P. falciparum glikolise gebruik. In hierdie tesis bied ons die biochemiese karakterisering van elk van die glikolitiese ensieme in P. falciparum trofozoïete aan. Die kinetiese vergelykings wat die kinetiese gedrag van die individuele ensieme beskryf, is geintegreer in ’n enkele kinetiese model. Die model waarop geen datapassing toegepas is nie, is gevalideer om eksperimenteel bepaalde bestendige-toestand metabolietkonsentrasies en fluksiewaardes, asook die eksperimentele inhibisie van die glukose transporter, te voorspel. Die gevalideerde model verskaf ’n bykomende hulpmiddel om teenmiddelteikens te identifiseer in P. falciparum glikolise. Metaboliese kontrole-analise en differensiële kontrole-analise het die glukose transporter, PfHT1, as ’n teenmiddelteiken geïdentifiseer, gebaseer op sy hoë kontrole van glikolitiese fluksie in die parasiet, tesame met ’n lae beheer van die glukose transporter op die fluksie in die gasheer eritrosiet. Dié differensiële kontrole maak die glukose transporter ’n aantreklike teenmiddelteiken, want selfs as beide die eritrosiet en die parasiet glukose transporters tot dieselfde mate geïnhibeer word, sal dit steeds ’n hoër glikolietiese fluksieinhibisie van die parasiet tot gevolg hê. Om die differensiële kontrole van die glukose transporter op die fluks te demonstreer en verdere bewyse te lewer dat PfHT1 ’n teenmiddelteiken kan wees, het ons die inhibisie van die glukosetransporter in geïsoleerde trofozoïete deur sitokalasien B ondersoek. Ons het ook die inhibisie van die laktaatproduksiefluksie deur sitokalasien B in beide geïsoleerde P. falciparum trofozoïete sowel as in eritrosiete ondersoek. Ons bevindings bewys dat differensiële kontroleanalise as ’n hulpmiddel vir teenmiddelteikenidentifikasie gebruik kan word en dat PfHT1 ’n aantreklike teenmiddelteiken is. In hierdie studie is die velde van biochemie en sisteembiologie gekombineer om ’n gedetaileerde kinetiese model van ongeslagtelike P. falciparum glikolise te konstueer en verskeie teenmiddelteikens in die metaboliese pad te identifiseer. Die modelvoorspelling sowel as eksperimentele bewyse van die differensiële flukskontrole van die glukose transporter in die gasheer en parasiet het PfHT1 uitgelig as ’n teenmiddelteiken en demonstreer ook die krag van differensiële kontrole analise in die identifisering van teenmiddelteikens binne ’n biologiese stelsel. Die kinetiese model is ’n waardevolle hulpmiddel vir die bevordering van ons begrip van P. falciparum glikolise en dit bied ’n goeie basis vir uitbreiding om teenmiddelteikens in die hele sentrale koolstofmetabolisme van P. falciparum te identifiseer.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Second-generation bioethanol is an alternative transportation fuel currently being investigated whereby cellulose, specifically lignocellulosic (woody) portions, of any plant mass can be converted to ethanol. To date, the technology had only been successfully implemented with demonstration scale facilities. Despite intensive research efforts at laboratory scale, no-one is certain what the secondary effects of scale-up to large systems are. The objective of this project was to develop threedimensional numerical models of a laboratory scale fermenter which could predict the effects of particulate mixing and reaction kinetics for future scale-up investigations. A numerical model of the reaction kinetics for simultaneous saccharification and fermentation of Avicel (microcrystalline cellulose) particles to ethanol is presented. The novelty of this model is the separation of the two primary cellulase enzyme-kinetics, which generated the capability to predict the heterogeneous behaviour of the enzyme-substrate interactions. This model improves the understanding of these systems while maintaining sufficient simplicity for implementation alongside a commercial computational fluid dynamics environment. Effects of the various fermentation medium constituents and the influence of each on the dynamic viscosity of the medium were also investigated. Results indicated that particle volume fraction had the dominant effect on the apparent dynamic viscosity resulting in further research of the particle properties. Due to the irregular shapes of Avicel particles, tests were conducted to determine drag and settling behaviour, which led to the development and modification of models to account for these phenomena. This investigation is unique as it allows a more accurate calculation of particle transportation through a three-dimensional environment including the effects of natural packing density. At lower particle volume fraction the concentration of ethanol and glycerol had the greatest effect on the apparent dynamic viscosity and was calculated from models obtained from literature. Validation of the physics and the incorporation thereof in the simulations resulted in the modification of various generic models which either improved numerical stability or accuracy, or both. Contributions included a modified form of the pressure force model, which proved significantly more stable and accurate than previous models proposed in literature. The models developed for capturing the effects of particles on the apparent dynamic viscosity proved effective for this specific substrate. Results from cross-coupling the reaction models with computational fluid dynamic simulations provide a novel approach to capturing the secondary effect of substrate conversion and particle distribution on the performance of the fermentation vessels. This is the first time where that biological reactions were successfully combined with particle dynamics and fluid flow fields to investigate the secondary effects which occur in fermenters. This work served as a foundation for future research and development within the bioethanol field with significant potential for expansion into other biochemical disciplines. / AFRIKAANSE OPSOMMING: Tweede-generasie bioetanol is ’n alternatiewe vervoerbrandstof wat tans ondersoek word waar sellulose, spesifiek lignosellulosiese (houtagtige) gedeeltes, van enige plantmassa na etanol omgesit kan word. Tot op hede was die tegnologie slegs suksesvol geïmplimenteer in demonstrasieskaal fasiliteite. Ten spyte van intensiewe navorsingpogings op laboratoriumskaal, is niemand seker wat die sekondêre effekte van die opskaal tot groot stelsels sal wees nie. Die doelwit van die projek was om drie-dimensionele modelle te ontwikkel van ’n laboratoriumskaal fermentor wat die effekte van partikulêre vermenging en reaksiekinetika kan voorspel vir toekomstige opskaal navorsing. ’n Numeriese model van die reaksiekinetika vir gelyktydige versuikering en fermentasie van Avicel (mikrokristallyne sellulose) partikels tot etanol word aangebied. Die oorspronklikheid van die model is geleë in die skeiding van die twee primêre sellulase ensiemkinetika, wat lei tot die vermoë om die heterogene gedrag van die ensiem-substraat interaksies te voorspel. Hierdie model verbeter die kennis van die stelsels, terwyl voldoende eenvoud behoue bly vir implementering parallel aan kommersiële berekeningsvloeidinamika sagteware. Effekte van die verskillende bestanddele van die fermentasiemedium en die invloed van elk op die dinamiese viskositeit van die medium is ook ondersoek. Resultate dui aan dat partikel volume fraksie die dominante invloed op die skynbare dinamiese viskositeit het, wat gelei het tot verdere ondersoek van die partikel eienskappe. As gevolg van die onreëlmatige vorms van Avicel partikels, is toetse gedoen om die sleur-en uitsakkingsgedrag te bepaal, wat gelei het tot die ontwikkeling en aanpassing van modelle om hierdie verskynsels in ag te neem. Hierdie ondersoek is uniek, want dit laat meer akkurate berekening van partikelvervoer deur ’n drie-dimensionele omgewing toe, insluitend die effekte van natuurlike verpakkingsdigtheid. By laer partikel volume fraksie het die konsentrasie van etanol en gliserol die grootste effek op die skynbare dinamiese viskositeit gehad en was bereken vanaf modelle in die literatuur. Bevestiging van die fisika en die insluiting daarvan in die simulasies het gelei tot die aanpasing van verskillende generiese modelle wat óf numeriese stabiliteit óf akkuraatheid óf beide verbeter. Bydraes gemaak sluit ’n aangepaste vorm van die drukkragmodel in, wat heelwat meer stabiel en akkuraat was as die vorige modelle voorgestel in die literatuur. Die modelle wat ontwikkel is om die effek van partikels op die skynbare viskositeit vas te vang, was effektief bewys vir hierdie spesifieke substraat. Resultate van die kruiskoppeling van inligting vanaf die reaksiemodelle met berekeningsvloeidinamika simulasies lewer ’n nuwe benadering tot die bepaling van die sekondêre effek van substraatomskakeling en partikeldistribusie op die uitvoering van die fermentasie toestel. Hierdie is die eerste poging om biologiese reaksies met partikel dinamika en vloeivelde te kombineer om die sekondêre effekte wat in fermenter plaasvind, te ondersoek. Hierdie werk dien as ’n grondslag vir toekomstige navorsing en ontwikkeling binne die bioetanolveld, met beduidende potensiaal vir uitbreiding na ander biochemiese dissiplines.

Dans cette thèse, une approche microcinétique expérimentale est utilisée pour caractériser des étapes élémentaires impliquées dans l’oxydation de CO par O2 sur des catalyseurs à base de Pd et d’Au supportés sur oxydes métalliques et identifier celles qui contrôlent la vitesse de réaction. Sur un catalyseur 1,4%Pd/Al2O3, l’évolution de la production de CO2 (RCO2(t)) par oxydation des espèces CO adsorbées (2 linéaires L et 2 pontées P) a été suivie lors de cycles successifs formation - oxydation des espèces. Une période d’induction est observée, donnant un pic de CO2 caractérisé partm et RCO2m. L’étude de l’impact de différents paramètres expérimentaux sur tm et RCO2m: le tempsde désorption avant oxydation, la pression partielle de O2, la température et le prétraitement ducatalyseur a permis de caractériser les étapes superficielles impliquées. Un modèle cinétique basé surl’oxydation des espèces CO P par une espèce oxygène faiblement adsorbée formée sur des sites libéréspar la désorption et/ou l’oxydation des espèces CO L a permis d’interpréter ces impacts. Ce modèle aégalement permis d’interpréter les différences d’activités du catalyseur vis-à-vis de la réaction CO/O2en fonction de son prétraitement après réduction sous H2 à 713 K : un refroidissement sous hydrogènepermet d’obtenir des conversions de CO proches de 100% à 300 K en excès de O2 alors qu’unedésorption préalable à 713 K donne de faibles conversions (< 4%). Ces différences sont attribuées àune reconstruction de la surface des particules de Pd par désorption de l’hydrogène à 713 K.Sur Au supporté sur Al2O3 et SiO2, l’étude a porté sur la première étape de l’oxydation du CO:l’adsorption du CO. Sous certaines conditions (température et pressions) l’adsorption de CO à 300 Kentraîne une reconstruction progressive des particules d’or modifiant significativement les propriétésdes espèces adsorbées. La cinétique de cette reconstruction à 300 K est étudiée et interprétée / The aim of this thesis is to use an experimental microkinetic approach to characterize elementary steps involved in the oxidation of CO by O2 over Pd and Au catalysts supported on Al2O3 and SiO2 and to identify those controlling the rate of the reaction. On 1.4% Pd/Al2O3, the evolution of the production of CO2 (RCO2(t)) by oxidation of the adsorbed CO species (2 linear L and 2 bridged B) was followed during successive formationoxidation cycles. An induction period is observed leading to a CO2 peak characterized by tm and RCO2m. The study of the impacts of different experimental parameters on tm and RCO2m such as the duration of a desorption before oxidation, the partial pressure of O2, the temperature and thepretreatment of the catalyst allows us to characterize the different surface elementary steps of thereaction. A kinetic model is proposed which is based on the oxidation of the B CO species by a weaklyadsorbed O species formed on Pd sites liberated by the desorption and the oxidation of the L COspecies. This model allows us to interpret the differences in the catalytic activity of the catalyst for theCO/O2 reaction according to the pretreatment procedure after reduction with H2 at 713 K: cooling thesolid in hydrogen permits obtaining a CO conversion of ��100% in excess O2 whereas a desorption at713 K provides CO conversions < 4%. These differences are ascribed to the reconstruction of thesurface of the Pd particles during the hydrogen desorption at 713 K. On Au/Al2O3 and Au/SiO2, the study concerns the first step of CO oxidation: the adsorption of CO. For a set of experimental conditions (Temperature and partial pressures), the adsorption of CO at 300 K leads to a progressive reconstruction of the Au particles modifying significantly the propertiesof the adsorbed species. The kinetic of this reconstruction is studied.

Dans le domaine automobile, intégrer de plus en plus de matériaux composites recyclés tout en améliorant les performances initiales et en diminuant les masses emportées devient un compromis auquel il faut répondre. Par ailleurs, les pièces de structures en matériaux composites destinées au crash sont souvent soumises à des conditions environnementales, notamment des températures modérément élevées, pouvant produire une dégradation physico-chimique progressive. Ainsi, pour assurer une meilleure conception et une durabilité des pièces, il est primordial de bien cerner l’influence du vieillissement thermique sur les propriétés dynamiques des matériaux. Dans ce but, ce travail vise à coupler la physique de la cinétique de dégradation par oxydation et le comportement mécanique multi-échelles d’un nouveau matériau composite totalement issu du recyclage à renfort carbone et matrice à base polypropylène. Le premier axe de l’étude est dédié à l’élaboration, la caractérisation physicochimique, microstructurale et mécanique de plusieurs formulations de composites. Une fois le composite optimal sélectionné, une méthodologie hybride, expérimentale et numérique, visant à caractériser les propriétés dynamiques rapides allant jusqu’à des vitesses de déformation de 100 s-1 est développée. Le deuxième axe de ce travail est focalisé sur l’étude de l’influence de la thermo-oxydation sur les propriétés physico-chimique et mécaniques à différentes vitesses de sollicitation du composite optimal et sa matrice. L’ensemble des données expérimentales issues du vieillissement a permis l’identification d’un modèle cinétique basé sur un schéma mécanistique de l’oxydation des matériaux vieillis. D’autre part, une étude qualitative et quantitative de l’effet du vieillissement sur les mécanismes d’endommagement a été réalisée à l’échelle microscopique visant à mettre en place une loi d’endommagement reliant, pour une déformation imposée donnée, le taux d’endommagement local à la concentration des produits d’oxydation. Les résultats de cette étude mettent en évidence la possibilité de développer des lois de comportement affectés par les paramètres de modèles cinétiques décrivant l’évolution de l’état physico-chimique du composite au cours du vieillissement. / In the automotive sector, integrating more and more recycled composite materials while improving the initial performance and decreasing the carried masses becomes a compromise that needs to be addressed. Moreover, structural parts made of composite materials intended for crash are often subjected to environmental conditions, including moderately high temperatures, capable of causing gradual physico-chemical degradation. Thus, to ensure better design and durability of parts, it is important to understand the influence of thermal aging on the dynamic properties of materials. To this end, this work aims to couple the physics of oxidative degradation kinetics and the multi-scales mechanical behavior of a new fully recycled composite based on a polypropylene matrix and carbon fibers. The first axis of the study is dedicated to the elaboration, the physicochemical, microstructural and mechanical characterization of several formulations of composites. Once the optimal composite is selected, a hybrid experimental and numerical methodology is s is developed in order to characterize the dynamic properties at high strain rates reaching 100 s-1. The second axis of this work is focused on the study of the influence of thermo-oxidation on the physicochemical and mechanical properties at different strain rates of the optimal composite and its matrix. The resulting experimental has allowed the identification of a kinetic model parameters based on a mechanistic scheme. Furthermore, a qualitative and quantitative study of the effect of aging on the damage mechanisms has been carried out at a microscopic scale in order to establish a damage law linking, for a given imposed strain, the local damage density to the concentration of the oxidation products. The results of this study highlight the possibility of developing behavioral laws affected by the parameters of kinetic models describing the evolution of the physicochemical state of the composite during aging.

In dieser Arbeit wird eine detaillierte Analysis des konsistenten kinetischen Modells zum Kornwachstum von Fradkov durchgeführt. Dieses Modell beschreibt - basierend auf dem von Neumann--Mullins Gesetz - die Flächenänderung eines Korns abhängig von seiner Topologieklasse, d.h. der Anzahl der Kanten. Topologieänderungen werden durch Kopplungsterme zwischen den Gleichungen für die Anzahldichten der verschiedenen Topologieklassen beschrieben. Daraus resultiert ein unendlich-dimensionales System von Transportgleichungen mit tridiagonaler Kopplungsstruktur. Durch eine spezielle Wahl des Kopplungsgewichts, welche die Gleichungen nichtlinear und räumlich nichtlokal macht, wird das Modell konsistent. Nach einer Einführung wird das Modell von Fradkov im zweiten Kapitel hergeleitet; formale Rechnungen zeigen die Konsistenz des Modells auf. Im dritten Kapitel wird das Kopplungsgewicht a priori beschränkt. Dadurch kann im ersten Teil des vierten Kapitels Existenz und Eindeutigkeit von Lösungen für endlich-dimensionale Systeme gezeigt werden. Weitere Schranken an die Anzahldichten im fünften Kapitel ermöglichen den Grenzübergang hinsichtlich der Anzahl der Gleichungen im zweiten Teil des vierten Kapitels. Die Existenz von Lösungen des unendlich-dimensionalen Systems wird somit über eine geeignete Approximation gezeigt. Energiemethoden liefern Eindeutigkeit und stetige Abhängigkeit von den Daten. Im sechsten Kapitel wird das Langzeitverhalten untersucht. Besonderes Augenmerk liegt dabei auf stationären Lösungen eines reskalierten Systems als Kandidaten für selbstähnliche Lösungen. Abschließend wird das Lewis''sche Gesetz asymptotisch verifiziert. / The subject matter of this thesis is a detailed analysis of the self--consistent kinetic model for grain growth introduced by Fradkov. The model is based on the von Neumann--Mullins law describing the change of area of grains according to their topological class, i.e. the number of edges they have. Topological events are performed by coupling terms between equations for the number densities of different topological classes. The resulting system of transport equations is infinite-dimensional with a tridiagonal coupling structure. Self-consistency of this kinetic model is achieved by introducing a coupling''s weight making the equations nonlinear and nonlocal in space. We start with an introduction in the first chapter. Afterwards in the second chapter we derive Fradkov''s model and carry out formal calculations to illustrate self-consistency. In the third chapter we present a priori calculations mainly allowing us to bound the nonlinearity. This enables us to prove existence and uniqueness of solutions to finite-dimensional systems in the first part of the fourth chapter. Further bounds on the number densities established in the fifth chapter allow for passing to the limit concerning the number of equations in the second part of the fourth chapter. Therefore we prove existence of solutions to the infinite-dimensional system by a suitable approximation procedure. Uniqueness and continuous dependence on the data is then provided by energy methods. The sixth chapter focusses on long-time behaviour and mainly on stationary solutions of a rescaled system as candidates for self-similar solutions. Finally we prove Lewis'' law asymptotically.

The objective of this study is to investigate the influence of sulfur compounds (S and Na2S) for powdered activated carbon derived from carbon black of pyrolyzed waste tires (CPBAC). Besides, this study investigated the distribution of impregnated sulfur in the inner pores of activated carbon and its effected on the specific surface area and pore size distribution. This study investigated the fundamental mechanisms by analysis of thermodynamic properties and to establish the kinetic models for the adsorption/desorption of HgCl2 by/from sulfur impregnated CBPAC. Furthermore, this study investigated the adsorptive and desorption capacity of HgCl2 onto CPBAC via thermogravimetric analysis (TGA). Experimental results indicated that the specific surface area of sulfur impregnated CBPAC with elemental S (S0) was larger than sulfur impregnated CBPAC with Na2S. Besides, the sulfur content of sulfur impregnated CBPAC increased with increasing the surface area of CBPAC under the same impregnated temperature. And, the adsorptive capacity of CBPAC increased with the increase of influent HgCl2 concentration and surface area of the activated carbon. According to the experimental results of the adsorption capacity under the differential sulfur content, its indicated that the affection of sulfur content for adsorption capacity of HgCl2 was much than HgCl2 concentration and surface area of the activated carbon. The desorption energys were 266 and 282 kJ/mole for HgCl2 desorption from saturated CBPAC-S0 and CBPAC-Na2S, respectively. The results showed the process of HgCl2 adsorption onto CBPAC was in favor of a physisorbed state of HgCl2 at the adsorption temperature of 150 oC but the process of HgCl2 adsorption onto CBPAC which impregated was in favor of a chemisorbed state of HgCl2 at the adsorption of 150 oC. The value of ∆G for CBPAC at the adsorption temperature of 30 ~150 oC were ranged from -15.28 kJ/mole to -26.63 kJ/mole. The value of ∆G for CBPAC-S0 at the adsorption temperature of 30~150 oC ranged from -23.45 kJ/mole to -32.09 kJ/mole. The value of ∆G for CBPAC-Na2S at the adsorption temperature of 30~150 oC ranged from -22.84 kJ/mole to -32.72 kJ/mole. The results showed negative values of ∆G confirmed the feasibility of adsorption process and the spontaneous nature for the adsorption of HgCl2. The value of ∆H for CBPAC at the adsorption temperature of 30 ~150 oC ranged from -35.58 kJ/mole to -35.82 kJ/mole. The value of ∆H for CBPAC-S0 at the adsorption temperature of 30 ~150 oC ranged from -38.07 kJ/mole to -52.49 kJ/mole. The value of ∆H for CBPAC-Na2S at the adsorption temperature of 30~150 oC was -37.45 kJ/mole to -53.12 kJ/mole. A negative ∆H suggested that the adsorption of HgCl2 is an exothermic process. Besides, the adsorptive behavior of HgCl2 for two activated carbons (CBPAC-Na2S and CBPAC-S0) at high temperature (110 ¢J and 150 ¢J ) was the same chemical reaction mechanism due to the same ∆H. Besides, the results of model simulation indicated that modified adsorption kinetic model based on pore diffusion scheme developed in this study could successfully simulate the transport and adsorption of HgCl2 by considering the chemical reaction within the inner pores of carbon grains at 150 oC.

This study combined photocatalytic technology with activated carbon cellulose-paper filter (ACCF) adsorption to decompose gaseous pollutants. Gaseous pollutants were initially adsorbed by activated carbon and could be further decomposed by photocatalytic technology. This study selected acetone (CH3COCH3) as gaseous pollutants. Two market available photocatalysts (photocatalysts¢¹and¢º) were coated on ACCF by impregnation to decompose acetone in a batch photocatlytic reactor. Operating parameters investigated in this study included initial acetone concentration (4.1~10.2 £gM), reaction temperature (40~70¢J), and water vapor (0~20 %). The incident UV light of 365 nm was irradiated by a 20-watt low-pressure mercury lamp placing above the batch photocatalytic reactor. The ACCF coated with TiO2 was placed at the center of the photocatalytic reactor. Acetone was injected into the reactor by a gasket syringe to conduct the photocatalytic tests. Reactants and products were analyzed quantitatively by a gas chromatography with an electron capture detector (GC/DCD) and a flame ionization detector followed by a methaneizer (GC/FID-Methaneizer). Finally, a Langmiur-Hinshewood (L-H) kinetic model was proposed to describe the rate of photocatalytic reaction. Results obtained from the photocatalytic tests indicated that photocatalyst¢º was better than photocatalyst¢¹ for the decomposition of acetone. Experimental results indicated that the size range of self-produced TiO2 photocatalyst by sol-gel was 20~70 nm. The end products were mainly CO and CO2, which resulted in the mineralization ratio up to 98%. Results obtained from the operating parameter tests revealed that the increase of initial acetone concentration enhanced the amount of acetone adsorbed on ACCF, which however did not increase the reaction rate of acetone. Although the increase of reaction temperature could reduce the amount of acetone adsorbed on ACCF, the decomposition rate of acetone could be promoted, so as the yield rate and mineralization ratio of products (CO and CO2). The increase of water vapor could slightly decrease the amount of acetone adsorbed on ACCF. The competitive adsorption phenomenon between acetone and water molecules on active sites could decelerate the decomposion of acetone. Moreover, the ACCF would not be saturated since the adsorbed acetone could be further decomposed quickly by the photocatalysts, which made the TiO2/ACCF more effective on removing acetone and lasted longer than the conventional ACCF. Finally, a modified bimolecular Langmuir-Hinshelwood kinetic model was developed to investigate the influences of initial acetone concentration reaction, temperature, and relative humidity on the promotion and inhibition for the photocatalytic oxidation of acetone. The modified L-H kinetic model could successfully simulate the photocatalytic reaction rate of acetone. Thus, the reaction rate of acetone over TiO2/ACCF could be described by the modified L-H kinetic model.

Pharmacodynamic studies are important for the optimal use of antimicrobial agents. Combination antifungal therapy may be one method to improve outcome in invasive Candida infections. An in vitro kinetic model to study the pharmacodynamic effects of a combination of two antifungal agents with different elimination rates was developed and the pharmacodynamics of amphotericin B (AMB), voriconazole (VRC) or the combination was evaluated. Exposure to VRC inhibited the fungicidal activity of sequential doses of AMB against VRC-susceptible strains of C. albicans. The interaction was VRC dose-dependent. AMB activity was regained once VRC was removed or it increased gradually when the concentration of VRC had fallen below the minimum inhibitory concentration (MIC). The VRC-AMB interaction, however, was also present against strains of C. albicans, C. glabrata and C. krusei despite reduced VRC susceptibility. Against these strains the interaction was not predicted by the MIC value, suggesting that mechanisms of resistance may be of importance. Until more data are available, a reasonable recommendation is probably to avoid the sequential use of VRC followed by AMB and to use the combination of VRC and AMB for the treatment of Candida infections with caution. Only the unbound fraction of a drug is generally accepted as pharmacologically active. The activity of posaconazole (POS) with a protein binding of 98-99% was tested in serum against Candida species and compared with the calculated unbound serum concentration in protein-free media. Significant differences emerged at clinically relevant POS serum concentrations of 1.0 and 0.10 mg/l compared with the serum control regimen against one strain of C. lusitaniae. In RPMI 1640 the corresponding calculated unbound concentrations resulted in no effect for the low dose regimen compared with the RPMI 1640 control regimen. Further, against seven additional Candida strains tested, the effect of POS was greater in serum than in RPMI 1640. A flux from serum protein bound to fungal lanosterol 14α-demethylase bound POS may be the explanatory mechanism.