A tbesis sutmitted to the Faculty of Engineering in fulfilment of the requirements for the degree of Doctor of Philosophy. / Available data on particularly viscosities of titaniferous melts under oxidizing conditions are reviewed, and an attempt is made to explain the high fluidity of such melts. (Abbreviation abstract) / Andrew Chakane 2018

It is a well-known fact that drugs can exist in different solid-state forms. These solid-state forms can be either crystalline or amorphous. Furthermore, significant differences are identified between the different solid-state forms of the same drug. Physico-chemical properties that are affected by the solid-state include: melting point, solubility, dissolution rate, stability, compressibility, processability, to name but a few. During the last two decades a significant amount of attention was directed towards the amorphous solid-state forms of drugs. The amorphous form is the direct opposite of the crystalline solid-state. While crystalline forms are constituted by unit cells arranged in a repetitive and structured nature, amorphous forms do not have a long-range order. This lack of order leads to an increase in the Gibbs free energy of such compounds which in turn leads to increased dissolution and solubility. The advantage of improved aqueous solubility and dissolution is a sought after characteristic within the pharmaceutical industry. Improved solubility ultimately could lead to improved bioavailability of a drug. In this study the amorphous nature and stability of amorphous azithromycin was studied. Although previous studies reported that amorphous azithromycin can be easily prepared, there is not a significant amount of data available on the stability of the amorphous form. Furthermore, the effect of milling, mixing, compression, handling and storage on the amorphous form was also investigated. This study showed that amorphous azithromycin remains stable during milling, mixing and compression. A compatibility study on azithromycin when mixed with tableting excipients showed some incompatibilities and this was helpful information to assist with the choice of excipients to be included in the tablet formulation. During the formulation study it became evident that good formulation strategies can greatly improve the flow properties of a drug. The stability of amorphous azithromycin was also studied. During this phase of the study an atypical stability indicating method was used in order to determine and demonstrate the stability of amorphous azithromycin. Dissolution studies were used to illustrate the stability of amorphous azithromycin due to the fact that dissolution is the only method that indicates the phenomena of solution-mediated phase transformation of an amorphous form to a stable crystalline form. During the stability study of six months at 40°C ± 75% RH no recrystallisation of the amorphous form to the crystalline form occurred. It was concluded that amorphous azithromycin will remain stable during processing steps, product formulation and manufacturing as well as during storage for a period of six months at elevated temperature and humidity. / MSc (Pharmaceutics), North-West University, Potchefstroom Campus, 2015

It is a well-known fact that drugs can exist in different solid-state forms. These solid-state forms can be either crystalline or amorphous. Furthermore, significant differences are identified between the different solid-state forms of the same drug. Physico-chemical properties that are affected by the solid-state include: melting point, solubility, dissolution rate, stability, compressibility, processability, to name but a few. During the last two decades a significant amount of attention was directed towards the amorphous solid-state forms of drugs. The amorphous form is the direct opposite of the crystalline solid-state. While crystalline forms are constituted by unit cells arranged in a repetitive and structured nature, amorphous forms do not have a long-range order. This lack of order leads to an increase in the Gibbs free energy of such compounds which in turn leads to increased dissolution and solubility. The advantage of improved aqueous solubility and dissolution is a sought after characteristic within the pharmaceutical industry. Improved solubility ultimately could lead to improved bioavailability of a drug. In this study the amorphous nature and stability of amorphous azithromycin was studied. Although previous studies reported that amorphous azithromycin can be easily prepared, there is not a significant amount of data available on the stability of the amorphous form. Furthermore, the effect of milling, mixing, compression, handling and storage on the amorphous form was also investigated. This study showed that amorphous azithromycin remains stable during milling, mixing and compression. A compatibility study on azithromycin when mixed with tableting excipients showed some incompatibilities and this was helpful information to assist with the choice of excipients to be included in the tablet formulation. During the formulation study it became evident that good formulation strategies can greatly improve the flow properties of a drug. The stability of amorphous azithromycin was also studied. During this phase of the study an atypical stability indicating method was used in order to determine and demonstrate the stability of amorphous azithromycin. Dissolution studies were used to illustrate the stability of amorphous azithromycin due to the fact that dissolution is the only method that indicates the phenomena of solution-mediated phase transformation of an amorphous form to a stable crystalline form. During the stability study of six months at 40°C ± 75% RH no recrystallisation of the amorphous form to the crystalline form occurred. It was concluded that amorphous azithromycin will remain stable during processing steps, product formulation and manufacturing as well as during storage for a period of six months at elevated temperature and humidity. / MSc (Pharmaceutics), North-West University, Potchefstroom Campus, 2015

Ce travail de recherche consiste à étudier les relations structure-propriétés de mélanges biopolymères à base de poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) et poly(butylène succinate) (PBS). Il est divisé en trois parties. La première partie est consacrée à l'étude des propriétés des mélanges PHBV/PBS préparés par voie fondue en fonction de la composition en termes de morphologie et de propriétés rhéologiques, mécaniques, thermiques et barrières. Les résultats obtenus ont été discutés par rapport aux polymères de base. La deuxième partie est consacrée à la compatibilisation des mélanges PHBV/PBS et l'amélioration des interactions à l'interface. Les effets de l'incorporation de la sépiolite à 5% en masse et du PHBV greffé par de l’anhydride maléique (PHBV-g-MA) à 5% en masse ont été étudiés en termes de changements morphologiques montrant un effet synergique entre le compatibilisant et la nanocharge sur les l’ensemble des propriétés des mélanges PHBV/PBS. Enfin, une étude sur le recyclage a été menée à travers une évaluation des effets du nombre de cycles d'extrusion sur les propriétés des matériaux. Elle révèle qu'après 6 cycles d'extrusion, la dégradation thermo-mécanique du PHBV est significativement réduite en présence du PBS. / The main objective of this work was to study the structure-properties relationships of biopolymerblends based on poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and polybutylene succinate (PBS). The work was devised into three parts. The first part was devoted to the study of the properties of PHBV/PBS blends prepared by melt compounding at different weight ratio in terms of morphology and properties. The results obtained were discussed in terms of properties and compared with the neat polymers. The second part was devoted to the study of compatibility of PHBV/PBS blends aiming to improve the interactions at the interface between the two components. The effects of both sepiolite (5% wt.) and PHBV-g-MA (5% wt.) were studied in terms of properties. The results showed a synergistic effect between the compatibilizer PHBV-g-MA and the nanofiller sepiolite though an increase in thermal, mechanical and rheological properties. The last part dealing with the recyclability of PHBV/PBS through the study of the effects of repeated extrusion cycles on the properties of materials. The results showed that after 6 reprocessing cycles the thermo-mechanical degradation of PHBV is significantly reduced in the presence of PBS.

O presente estudo teve como objetivo avaliar a influência do protocolo de secagem com álcool isopropílico à adesividade dos cimentos AH Plus, Hybrid Root Seal e Epiphany SE à dentina radicular. Oitenta raízes de caninos foram submetidas ao preparo biomecânico e distribuídas em 2 grupos de acordo com a secagem, previamente a obturação: I- Secagem cone de papel absorvente e II- Secagem com álcool isopropílico 70%,e posteriormente distribuídas em 8 grupos (n=10): IA e IIA cimento AH Plus; IB e IIB - cimento Hybrid Root Seal; IC e IIC- cimento Epiphany SE com guta percha e ID e IID cimento Epiphany SE com Resilon. Após a obturação, 80 raízes foram seccionadas transversalmente obtendo-se 3 slices de 1,0 mm de espessura para cada terço radicular. Um slice de cada terço foi submetido ao teste de push out e tipo de falha analisado por meio de lupa estereoscópica. Os dois slices restantes foram submetidos à MEV para análise da interface adesiva e superfície do material obturador. A análise de variância evidenciou haver diferença estatisticamente significante (p<0,05) entre os materiais obturadores, o protocolo de secagem do canal radicular e a interação destes fatores. AH Plus/ guta percha obteve os maiores valores médios de resistência de união (3,83 ± 0,45 MPa), sendo estatisticamente diferente (p<0,05) dos demais. O Hybrid Root SEAL/ guta percha (3,24 ± 0,46 MPa) obteve valores intermediários, sendo estatisticamente diferente dos demais (p<0,05). O cimento obturador Epiphany SE quando associado à guta percha (0,45 ± 0,10 MPa) ou ao Resilon (0,31 ± 0,09 MPa) obteve os menores valores de adesividade, sendo estatisticamente semelhantes entre si (p>0,05) e diferentes dos demais (p<0,05). O cimento AH Plus obteve os maiores valores de adesividade independente do protocolo de secagem utilizado. Na comparação entre os protocolos, o protocolo que utilizou álcool isopropílico 70% obteve maiores valores médios de adesividade. / The purpose of the present study was to evaluate the influence of the drying protocol with isopropyl alcohol on the adhesion of the sealers AH Plus, Hybrid Root Seal and Epiphany SE to intraradicular dentin. Eighty root canals of canines were subjected to biomechanical preparation and were allocated to receive one of the following drying protocols (n=40) prior to root canal filling: I- Drying with absorbent paper point and II- Drying with 70% isopropyl alcohol. Thereafter, 8 groups (n=10) were formed according to the filling material: IA and IIA AH Plus sealer; IB and IIB - Hybrid Root Seal sealer; IC and IIC- Epiphany SE sealer with gutta-percha; and ID and IID Epiphany SE sealer with Resilon. After filling, the 80 roots were sectioned transversally to obtain three 1.0-mm-thick slices from each root third. The first slice of each third was subjected to a push-out test and the failure mode was determined with a stereoscopic lens. The other two slices were prepared for SEM to examine adhesive interface and the surface of the filling materials. Analysis of variance revealed statistically significant difference (p<0.05) among the filling materials, between the root canal drying protocols as well as for the interaction of these factors. AH Plus/gutta-percha had significantly higher (p<0.05) bond strengths (3.83 ± 0.45 MPa) than the other materials. Hybrid Root SEAL/gutta-percha (3.24 ± 0.46 MPa) had intermediate values and differed significantly from the other materials (p<0.05). Epiphany SE combined with either gutta-percha (0.45 ± 0.10 MPa) or Resilon (0.31 ± 0.09 MPa) presented the lowest bond strengths without statistically significant difference (p>0.05) from each other, but with significant difference (p<0.05) from the other materials. AH Plus present the highest bond strengths regardless of the drying protocol. Comparing the two protocols, drying of root canals with 70% isopropyl alcohol was associated with the highest bond strength values to intraradicular dentin.

Fast-paced lifestyles result in consumers replacing traditional meals with on-the-go snack foods. In general, snacks are higher in saturated fats and simple sugars, and pose health concerns for consumers, which prompts the need for healthy nutritious alternatives to common snacks. Proso millet is a nutritious, and fast growing gluten free cereal. Spent grain (SG), the main by-product of brewing and distilling, contains high amount of protein and insoluble fibers. This study utilized proso millet and spent grain in the production of an extruded expanded snack, demonstrating their appropriateness as an ingredient in food production. The first objective of this study was to determine the effect of extrusion processing conditions (moisture, barrel temperature, screw speed) on the physical, chemical, and functional properties of proso millet based extruded snack. The second objective of this research was to determine the effect of distiller’s spent grain (DSG) addition level and particle size on physicochemical and functional properties of extruded snacks. The third objective of this research was to evaluate the effect of spent grain type and particle size on the physicochemical and functional properties of extruded snacks. Samples were produced using a co-rotating twin-screw 25:1 L/D laboratory scale extruder.

Numerical descriptors, beginning with Wiener, and then named topological indices by Hosoya, have gained gradually increasing importance along with other descriptors for use in QSAR and QSPR studies. Being able to estimate the physical or chemical properties of a yet nonexistent substance as close as possible is very important due to huge consumption of time and money upon direct synthesis. In addition, one may face safety problem as in the case of explosives. There have been almost hundred topological indices so far in the chemical graph theory literature. However, there is no topological index which is generalizable to all kinds of molecules. In the present study, a novel topological index (TG Index) has been developed and applied to a wide range of organic molecules including explosives for modeling their physical, structural and molecular orbital properties. The index yielded quite successful correlation data with most of the properties considered in this study.

O presente estudo teve como objetivo avaliar a influência do protocolo de secagem com álcool isopropílico à adesividade dos cimentos AH Plus, Hybrid Root Seal e Epiphany SE à dentina radicular. Oitenta raízes de caninos foram submetidas ao preparo biomecânico e distribuídas em 2 grupos de acordo com a secagem, previamente a obturação: I- Secagem cone de papel absorvente e II- Secagem com álcool isopropílico 70%,e posteriormente distribuídas em 8 grupos (n=10): IA e IIA cimento AH Plus; IB e IIB - cimento Hybrid Root Seal; IC e IIC- cimento Epiphany SE com guta percha e ID e IID cimento Epiphany SE com Resilon. Após a obturação, 80 raízes foram seccionadas transversalmente obtendo-se 3 slices de 1,0 mm de espessura para cada terço radicular. Um slice de cada terço foi submetido ao teste de push out e tipo de falha analisado por meio de lupa estereoscópica. Os dois slices restantes foram submetidos à MEV para análise da interface adesiva e superfície do material obturador. A análise de variância evidenciou haver diferença estatisticamente significante (p<0,05) entre os materiais obturadores, o protocolo de secagem do canal radicular e a interação destes fatores. AH Plus/ guta percha obteve os maiores valores médios de resistência de união (3,83 ± 0,45 MPa), sendo estatisticamente diferente (p<0,05) dos demais. O Hybrid Root SEAL/ guta percha (3,24 ± 0,46 MPa) obteve valores intermediários, sendo estatisticamente diferente dos demais (p<0,05). O cimento obturador Epiphany SE quando associado à guta percha (0,45 ± 0,10 MPa) ou ao Resilon (0,31 ± 0,09 MPa) obteve os menores valores de adesividade, sendo estatisticamente semelhantes entre si (p>0,05) e diferentes dos demais (p<0,05). O cimento AH Plus obteve os maiores valores de adesividade independente do protocolo de secagem utilizado. Na comparação entre os protocolos, o protocolo que utilizou álcool isopropílico 70% obteve maiores valores médios de adesividade. / The purpose of the present study was to evaluate the influence of the drying protocol with isopropyl alcohol on the adhesion of the sealers AH Plus, Hybrid Root Seal and Epiphany SE to intraradicular dentin. Eighty root canals of canines were subjected to biomechanical preparation and were allocated to receive one of the following drying protocols (n=40) prior to root canal filling: I- Drying with absorbent paper point and II- Drying with 70% isopropyl alcohol. Thereafter, 8 groups (n=10) were formed according to the filling material: IA and IIA AH Plus sealer; IB and IIB - Hybrid Root Seal sealer; IC and IIC- Epiphany SE sealer with gutta-percha; and ID and IID Epiphany SE sealer with Resilon. After filling, the 80 roots were sectioned transversally to obtain three 1.0-mm-thick slices from each root third. The first slice of each third was subjected to a push-out test and the failure mode was determined with a stereoscopic lens. The other two slices were prepared for SEM to examine adhesive interface and the surface of the filling materials. Analysis of variance revealed statistically significant difference (p<0.05) among the filling materials, between the root canal drying protocols as well as for the interaction of these factors. AH Plus/gutta-percha had significantly higher (p<0.05) bond strengths (3.83 ± 0.45 MPa) than the other materials. Hybrid Root SEAL/gutta-percha (3.24 ± 0.46 MPa) had intermediate values and differed significantly from the other materials (p<0.05). Epiphany SE combined with either gutta-percha (0.45 ± 0.10 MPa) or Resilon (0.31 ± 0.09 MPa) presented the lowest bond strengths without statistically significant difference (p>0.05) from each other, but with significant difference (p<0.05) from the other materials. AH Plus present the highest bond strengths regardless of the drying protocol. Comparing the two protocols, drying of root canals with 70% isopropyl alcohol was associated with the highest bond strength values to intraradicular dentin.

Green garden peas (Pisum sativum L.) are a popular vegetable used in meal preparation worldwide. Green peas are commonly available in their frozen form due to their short growing season. Green peas are easily susceptible to changes in the field, immediately after harvest, during processing and storage, and thereforerequire careful handling to maintain good quality. The acceptability of frozen green peas is greatly dependent on the sensory quality. Descriptive sensory profiles and physico-chemical properties of frozen green peas can be investigated and used to assess and explain product quality. Six brands of frozen green peas representing product sold for retail and caterer's markets were purchased and subjected to descriptive sensory evaluation, physico-chemical analyses and quality grading. Four batches with different best before dates were purchased for each brand. Quality grading was done using statutory standards and a selected company protocol. Dry matter content, alcohol insoluble solids content, starch content, °Brix, residual peroxidase activity, size sorting, hardness using texture analysis and colour measurements were carried out for physico-chemical analyses. Generally, retail class peas were of superior sensory quality to caterer's peas although one caterer's brand had quality traits that were more comparable with the retail brands than the other caterer's brands. Quality grading revealed that frozen green peas can be downgraded due to poor colour, presence of extraneous vegetable matter, presence of sandy grits and soil stains, poor flavour and poor texture. Downgrading of peas can be due to one reason or due to a combination of two or more poor quality characteristics. Good quality peas were described as sweeter, smaller, greener, more moist and more tender than the poorer quality peas usingdescriptive sensory evaluation. Good peas also had high °Brix content, more intense green colour, low starch, alcohol insoluble solids, dry matter contents and texture hardness measured. Quality grading revealed that flavour problems were the major cause for low graded samples. Sensory evaluation and the methods used for instrumental analyses however, showed more easily the variations in texture attributes than flavour attributes of peas. Poor flavour was probably caused by ineffective blanching, low soluble solids content which enhanced the perception of bitterness and the presence of acetone notes. Poorly coloured peas were also either underblanched or had low moisture contents. Mealiness and hardness in peas were explained by high starch, alcohol insoluble solids and dry matter contents. Instrumental texture analysis showed indications that the harder peas also had tougher skins in addition to harder cotyledons. Lower peas also displayed characteristics typical of delayed harvesting and post-processing temperature abuse such as dehydration and pale green/white colouration. The sensory quality of frozen green peas can be predicted from the physico-chemical methods of analysis used in this study. Some of the frozen peas on sale are below the acceptable standards of quality. To achieve good frozen pea quality it is important to put emphasis on maturity at harvest and post processing storage conditions (store at -18 °C or lower and avoidfluctuatingtemperatures). The use of a strict quality grading scheme has been shownto result in good quality frozen peas. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Food Science / unrestricted

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