Introduction: Coenzyme Q10 (CoQ10) is a fat-soluble substance (ubiquinone) which has a bright orange color in appearance and is widely distributed (ubiquitous) in animals and many bacteria. CoQ10’s presence is most prevalent in mitochondria and it is involved in aerobic cellular respiration and aides in converting ingested nutrients into a readily accessible form of energy, specifically ATP (adenosine triphosphate). CoQ10 is supplied through our diets and can be found more in dark leafy green vegetables, fish and organ meats. CoQ10 supplementation should be beneficial due to its characteristic antioxidant scavenging of free radicals that our body produces while in the cellular respiration process for generating energy from nutrients. Although CoQ10 has great antioxidant benefit, a challenge remains for supplement manufacturers to deliver a sufficient does of this sparingly soluble molecule. Dietary supplements do not have the significant FDA oversight that exists for legend drugs, resulting in significant variability within and between brands. The main hypothesis of this project is that commercially available CoQ10 supplements don’t deliver a sufficient mass of CoQ10 when compared to the labelled quantity. Methods: To test this hypothesis, the group purchased and tested 14 commercially available CoQ10 supplements with each serving containing 100 mg of active, choosing a variety of drug delivery systems (DDS) and also included one in-house product, which contained 70 mg of active. The DDSs examined consisted of 7 soft shell gelatin (SSG) capsules (the most common type available), 3 hard shell gelatin (HSG) capsules, 3 tablets (tab), 1 powder, and 1 suspension. Each DDS was placed into a 500 mL volumetric flask (VF) into an aqueous of 0.1 N HCl acid and 0.1% Tween 80, using a standard FDA dissolution method. To facilitate drug release, the contents were removed from the HSG capsules; the SSG capsules were perforated; and the tabs were broken/crushed. After this, a magnetic stir bar was placed into each flask and all DDS samples were vigorously stirred for 30-45 minutes, including being inverted every 10 minutes to further facilitate dissolution of CoQ10 from each DDS. Filtered samples were obtained and the samples were analyzed by a reverse-phase High Performance Liquid Chromatography that was previously developed by this research group. Results and Conclusions: Only two of the 15 products evaluated had significant availability (mean > 50%) of CoQ10; one soft gelatin capsule (Product A, dissolved a mean of 68.57%), and the suspension (Product K, dissolved a mean of 56.71%). All of the other products averaged less than 4% dissolution of the labelled amount (range of values 0.19% to 3.64%). The in-house formulated HSG capsule (Product Q) released a mean amount equal to 8.11% of label (more than twice the percentage of the poorly performing commercial products). The consistency of the products was also variable, with product A having a range of 1.7 to 192 mg of CoQ10 released; Product K had a range of 35.8 to 76.1 mg of drug released. The group concluded that there are acceptable products available, but that most have significant performance issues.

Magister Pharmaceuticae - MPharm / The overall objective of this research is to attempt to produce, by direct compression, indomethacin tablets which have good dissolution characteristics and an improved bioavailability profile, when compared to the capsule formulations currently available. In order to use the direct compression method, the solubilized form of indomethacin should have good flow properties, as well as a small bulk volume for incorporation into reasonably sized tablets.

En puisant dans différentes traditions de l’histoire intellectuelle et en faisant appel au savoir cumulé par la sociologie des intellectuels, la thèse propose un examen critique de l’univers des sciences sociales en Serbie et en Croatie, de leur production et de leurs reconfigurations, durant la dissolution yougoslave, en se concentrant sur la période qui va de la disparition de la Ligue des Communistes de Yougoslavie en 1990, à la fin de la guerre en Bosnie en 1995. La recherche reconstruit et analyse dans un premier temps quelques-uns des principaux débats et réflexions développés dans le monde scientifique et intellectuel yougoslave et (post)yougoslave depuis la période socialiste, sur la base de publications périodiques, de livres et de travaux inédits. L’étude se concentre notamment sur la période de la dissolution du pays et elle examine en détail les réflexions des sciences sociales autour des grandes problématiques des années 1990, telles que la guerre, la montée du nationalisme, la transition politique et économique et enfin, les nouvelles manières de penser la modernisation à l’époque de la globalisation. Dans un second temps, à partir d’entretiens en profondeur menés avec des chercheurs et à partir de documents institutionnels, matériaux statistiques et documents de presse, la recherche décrit et analyse le monde des sciences sociales dans la République Fédérale Socialiste de Yougoslavie, ainsi que ses reconfigurations pendant la crise et la dissolution du pays. La thèse s’intéresse surtout aux transformations des conditions de production des chercheurs dans la première moitié des années 1990, une période caractérisée par l’effondrement du système socialiste, le début de la guerre dans la région, la rupture des liens de coopération panyougoslaves, la crise économique, la montée de l’autoritarisme et le recul général de l’espace (post)yougoslave dans le système mondial. / Drawing from different traditions of intellectual history, as well as from the sociology of intellectuals, the dissertation proposes a critical examination of the univers of social sciences in Serbia and Croatia, their production and reconfiguration, during the breakup of Yugoslavia. The work focuses on the period that goes from the dissolution of the League of Communists of Yugoslavia in 1990 to the end of the war in Bosnia in 1995. On the one hand, the research reconstructs and analyses some of the main debates and reflections that took place in the Yugoslav and (post)Yugoslav scientific and intellectual world from the socialist period onwards, drawing from scientific journals, books and unpublished works. The study focuses especially on the period of the country's disintegration, examining in detail the reflections in social sciences around some of the main issues of the 1990s such as war, nationalism, political and economic transition and new approaches to modernization characteristic of the era of globalisation. On the oher hand, ressorting to in-depth interviews conducted with researchers, as well as institutional documents, statistical materials and sources from the press, the research describes and analyzes the world of social sciences in the Socialist Federal Republic of Yugoslavia and its reconfigurations during the crisis and dissolution of the country. The thesis particularly addresses the transformations that took place in the conditions of production for local researchers during the early 1990s, a period that was characterized by the collapse of the socialist system, the beginning of war in the region, the breakup of panyugoslav scientific and intellectual links, economic crisis, the rise of authoritarianism and the general regression of the (post)Yugoslav space in the global system.

First-principle modelling of chemical processes and their unit operations has been of great interest in the chemical process, as well as the control and allied industries over the past decades. This is because it offers the opportunity to develop virtual representations (models) of real process systems, which can be used to describe and predict the dynamic behaviour of those systems. These models are based on the fundamentals of the transport phenomena of fluid dynamics (involving momentum transfer), mass transfer, and energy transfer of the systems they describe. A first-principle model of a semi-batch rhodium dissolution chemical process has been developed. It describes the dynamic behaviour of two exothermic reactions, occurring simultaneously in a semi-batch process. The dissolution of 29 kg of solid crude rhodium sponge (Rh) into 546 L of a solution of hydrochloric acid (HCl(aq)), to produce a solution of aqueous rhodium(III) chloride (RhCl3.H2O), as well as the reaction of chlorine (Cl2(aq)) with water (H2O(l)) to produce some more HCl(aq) in the reactor. The model was formulated as a system of explicit ordinary differential equations (ODEs), which demonstrated some good and stable qualitative tracking of the temperature and pressure data of the real reactor. The molar responses of all chemical species, as well as the heats of reactions, showed to be consistent with the description of the process, and no negative values of those variables were generated. Estimates of the key parameters of heat and mass transfer coefficients, arrhenius constants, and activation energies of reactions were assumed and tuned to satisfaction by trial-and-error, but not optimised. This is because during simulations, the numerical solver would often fail to integrate the equations, due to the appearance of large derivatives in some model equations whenever those parameters varied, thereby stopping simulations. Finally, the model was validated with a set of data from 45 batches. For all simulations done, the simulated temperature responses showed better prediction of data than the simulated pressure responses did, with an average percentage accuracy of 80% against 60 percent, respectively. / Dissertation (MSc)--University of Pretoria, 2017. / Anglo American Platinum / BluESP (Pty) Ltd / Chemical Engineering / MSc / Unrestricted

The aim of this paper is to evaluate the effects of the dissolution time – time for the liquid to absorb the gas till the saturation state - on the behaviour of positivedisplacement vane pumps, in terms of pressure peaks within internal chambers and forces applied to the stator ring. The chamber pressurization depends on the volume variation and fluid Bulk modulus in the pre-compression phase during which the volume is trapped between the suction and the delivery port rims. If the dissolution time is short, then the entrained air is quickly absorbed and the fluid Bulk modulus sharply increases just before opening the connection to the outlet; as a consequence, pressure peaks may appear thus degrading the NVH characteristics of the pump. Moreover the pressure within internal chambers generate i) a torque demand to the driver (the combustion engine or an electrical motor) and ii) a total force applied to the stator ring. In case of fixed displacement designs, the resultant pressure force simply represents a load for support bearings; while in case of variable designs, it contributes to the displacement regulation. Simulation results show that the pump behaviour is very sensitive to the dissolution time when it is quite close to the duration of the trapped period.

The success of an amorphous solid dispersion (ASD) formulation, consisting of a homogeneous molecular dispersion of drug and polymer, relies on its ability to create and maintain a supersaturated solution. However, supersaturated solutions are metastable and prone to crystallization. In solution, crystals are expected to serve as a template for crystal growth, depleting achieved supersaturation. Thus, in an ASD product, ideally no crystallinity should be present. However, technical challenges exist in both processing and characterization to routinely ensure this is achieved. The presented studies follow the process design, characterization, and dissolution performance of hot melt extruded amorphous solid dispersions, seeking insight into the significance of critical quality attributes of resulting extrudates, namely residual crystallinity and thermal degradation.<div>Selection of hot melt extrusion (HME) processing conditions to prepare ASDs is governed by thermodynamic and kinetic attributes of the drug and polymer system. Mapping the temperature-composition phase diagram to HME processing conditions provides a processing design strategy to prevent residual crystallinity while simultaneously avoiding thermal degradation. Through processing temperatures below the drug’s melting point (Tm) and above the formulation critical temperature (Tc), fully amorphous systems could be generated if sufficient kinetics were provided. The utility of thermogravimetric analysis was critically examined for prediction of the chemical stability processing window for HME formulations.<br></div><div>For characterization and product performance characterization, residual crystalline content in HME ASDs can be anticipated and tailored to various levels. Several HME ASDs were characterized by a range of analytical techniques, highlighting the sensitivity of available techniques to qualitatively or quantitatively detect crystalline content (depending on limitations which stem from properties of the instrument or sample). Transmission electron microscopy (TEM) was found to identify low levels of crystallinity not observed by other technique and provide insight into crystal dissolution mechanisms. A defect-site driven dissolution and fragmentation model was suggested, and supported by a Monte Carlo simulation, underscoring that crystal defect sites, either intrinsic to the crystals or formed during processing, expedite dissolution rates and generation of new surfaces for dissolution.<br></div><div>Non-sink dissolution was performed for indomethacin/PVPVA HME ASD samples with residual crystallinity ranging from 0-25% crystalline content. Due to effective crystal growth inhibition by the polymer, crystals had little impact on dissolution performance. Achieved supersaturation was reduced approximately by the level of crystallinity present, i.e. a lost solubility advantage. These studies have significance for HME processing design and risk assessment of crystallinity within ASD formulations.<br></div>

NR 20140805

Oxidative dissolution of std. UO2 and UO2 doped with Cr2O3 and Al2O3, i.e. ADOPT, induced by H2O2 and γ radiation has been the main focus in this licentiate thesis. The catalytic decomposition of H2O2 on oxides like Gd2O3, HfO2, CeO2, Fe2O3 and CuO were also investigated. A kinetic study was performed by determining first and second order rate constants together with Arrhenius parameters for the decomposition of H2O2. The reactivity of H2O2 towards the oxides mentioned was observed to differ significantly despite their similarities. In the mechanistic study, the yields and dynamics of the formation of the intermediate hydroxyl radical from the decomposition of H2O2 was determined for the oxides and found to differ considerably. A turnover point could be found for most of oxides studied, i.e. an increase in the rate of hydroxyl radical scavenging after a specific amount of consumed H2O2. The reactivity of the std. UO2 and ADOPT towards H2O2 was similar to what was observed for other UO2-based materials in previous studies. The oxidative dissolution in radiation experiments showed a slight but significant difference. This was attributed to a difference in exposed surface area instead of an effect of doping. The difference in oxidative dissolution yield was too small to be significant which supports the previous conclusion. Leaching experiments using spent nuclear fuel were also performed on the two types of fuel showing the same behavior as the unirradiated pellets, i.e., a slightly lower 238U release from ADOPT. The difference was attributed to difference in exposed surface area. The release of fission products with low UO2 solubility displayed a higher release from ADOPT which was attributed to a difference in matrix solubility. Cs was released to a larger extent from std. UO2. This is attributed to the larger grain size of ADOPT, extending the diffusion distance. The release of lanthanides and actinides was slightly higher for the conventional UO2, nevertheless the difference was relatively small. / <p>QC 20140527</p>

The termination of a romantic relationship, be it by breakup or divorce, is a fairly ubiquitous experience. Most individuals will recover from a traumatic experience of this nature; some however, experience substantial difficulties in recuperating that persist over time. For these individuals, relationship termination can invoke a variety of negative physical and psychological health outcomes. This project examines the role of social cognitive maturity, operationalized as Interpersonal Decentering, in recovery following a relational loss. Participants in this study were assigned to a pre/post control or measurement intensive (four visits) condition over the course of nine weeks. Individuals in the latter condition completed a Stream of Consciousness (SOC) task in which they discussed their breakup experience out loud for four minutes. These narratives were then transcribed and scored using the Interpersonal Decentering manual as adapted for Expressive Writing. Results indicate that – for women only – mature social cognition is inversely related to depressive mood at the initial visit. However, it is not related to initial PSTD symptomatology for men or women, nor does it predict decreases in depression and trauma symptomatology from the initial visit to the nine-week follow-up. Implications, limitations, and future directions for research of this nature are discussed.

Struvite is a salt that is formed out of  Mg2+,NH4+ and PO43- and it crystallizes in form of MgNH4PO4.6H2O. Struvite‟s (magnesium ammonium phosphate or MAP) precipitation has recently been regarded as an interesting technique to remove phosphate and ammonium from waste water. The high elimination rates and the possibility of recycling the struvite as a direct slow release fertilizer make this process feasible and appealing. However, the costs due to the raw chemicals needed are drawbacks that leave aside the application of the process in some facilities. The MAP biological dissolution makes possible a recycling of magnesium and phosphate, a fact that reduces the process‟s costs and will help making it even more feasible and environmentally friend. This thesis goes also through the parameters, reactions and different techniques that optimize the struvite precipitation process.