Diss. (sammanfattning) Uppsala : Univ., 2002. / Härtill 5 uppsatser.

Includes bibliographical references (p. 91-95).

Thesis (Ph. D.)--University of Rhode Island, 2004. / Typescript. Includes bibliographical references (leaves 88-97).

Nanozirconia ceramics have great potential to be used in a range of applications from dental implants to petrochemical valves due to their enhanced mechanical properties and superior hydrothermal ageing resistance. Unlike conventional ceramic components that are normally produced in large quantities with low costs using various conventional dry forming or wet forming methods, industry scale processing of nanoceramics has not yet been achieved. Concentration and granulation of nanostructured 3 mol% yttria stabilised zirconia via a spray freeze drying (SFD) technique was investigated to determine whether large scale dry forming of nanoceramics would be possible. Commercial nanosuspension with a primary particle size of 16 nm was concentrated to 55 wt% solids content using an electrosteric dispersant, β-alanine, whilst retaining low viscosities of ~20 mPa s at a 200 s-1 shear rate. The nanosuspensions concentrated using the β-alanine also displayed good ageing resistance and it has been proven that a large scale vacuum assisted rotary evaporator can be used to perform concentration in industry.

Enzimas são proteínas utilizadas em processos tecnológicos diversos. Estas enzimas dependendo do tipo e grau de pureza são geralmente caras. Comumente as enzimas exigem controle contínuo do processo no que se refere à temperatura, pH, agitação, entre outros, e após o uso são descartadas, o que torna o custo do processo mais elevado. Em decorrência disto, a imobilização de enzimas em suportes insolúveis e inertes, vem sendo proposta com resultados promissores de manutenção e até mesmo aumento da atividade enzimática, resistência mecânica, térmica e de pH, bem como por apresentar maior facilidade de remoção da enzima do sistema e possibilitar sua reutilização. Por causa disto, diferentes tipos de suportes vêem sendo estudados, dentre estes, os materiais poliméricos, tem recebido atenção especial. A quitosana é um polímero natural, biocompatível, biodegradável e atóxico. É obtida de fontes renováveis provenientes do descarte de cascas de crustáceos da indústria de alimentos, o que constitui um fator ambiental importante atualmente. Neste trabalho a enzima pepsina foi imobilizada em membranas liofilizadas de quitosana e O-carboximetilquitosana reticuladas ou não com glutaraldeído. A pepsina imobilizada na membrana de quitosana reticulada com glutaraldeído manteve sua atividade enzimática e o suporte apresentou propriedades físico-químicas de resistência a solubilização em pH ácido, o qual é necessário para atividade da pepsina. O processo de liofilização preservou a estrutura do suporte e não comprometeu a atividade enzimática. Demonstrando que o processo de liofilização é viável para secagem e incorporação de enzimas. / Enzymes are proteins used in a wide variety of biotechnological processes. Commonly, enzymes require stringent conditions, such as a particular pH, temperature, stirring, etc. In chemical and biochemical reactions, purified enzymes can be rather costly and additionally, must be discarded after each use, which is still less economical. As a result of this, enzyme immobilization on insoluble and inert supports has been studied as a manner to overcome these problems and optimize enzymes use. Promising results of greater immobilized enzyme activity and stability over a broader range of pH and temperature have been reported. As well, immobilized enzymes can be easily removed from the system and reused. Various materials have been employed as enzymes supports, among then, the polymers have received special attention. Chitosan is a natural polymer that presents biocompatibility, biodegradability and nontoxicity. Chitosan is obtained from crustacean shell wastes discarded by the food industry, and recover this material constitutes an important environmental factor nowadays. In this work the enzyme pepsin was immobilized on freezedried chitosan and O-Carboxymethylchitosan membranes crosslinked or not with glutaraldehyde. Pepsin immobilized on chitosan membrane crosslinked with glutaraldehyde maintained its enzymatic activity and the polymer support provided physicochemical properties such resistance to dissolution in acid pH. Acid pH is required for pepsin activity. The freeze-drying process preserved the support structure and did not compromise the enzymatic activity. Demonstrating that, freeze drying process, is viable for drying and enzymes incorporation.

Magister Pharmaceuticae - MPharm / Leonotis leonurus, a South African indigenous medicinal plant, is frequently used in the form of a tea. However, this dosage form has many disadvantages. Consequently three L. leonurus solid extract preparations were prepared and explored as possible replacements of the tea form, but very little was known about their physical and chemical stability during storage. The specific objectives were to: (i) prepare a freeze dried aqueous extract (FDAE), 20 % aqueous ethanol (Aq EtOH) extract and calcium alginate beads of the FDAE form of L. leonurus, (ii) characterize the extracts using parameters of select physical and chemical features and, (iii) determine the long-term stability of the extracts. It was hypothesised that the Aq EtOH extract would contain higher levels of chemical marker compounds (marrubiin and leonurine) than the FDAE and calcium alginate FDAE beads of L. leonurus and, that the calcium alginate FDAE beads would have greater stability (i.e. longer shelf-life) than the FDAE and the Aq EtOH extract. The three L. leonurus solid extracts were prepared using accepted published methods. For the physical characterization of the extracts, the organoleptic properties were determined using the natural senses (e.g. sight, smell, taste, etc.) and for chemical characterization, total phenol content (TPC; using the Folin-Ciocalteu reagent method), total flavonoid content (TFC; using aluminium chloride-methanol solution) and antioxidant activity (using the -diphenyl-2-picryl-hydrazyl (DPPH) assay). To establish the long-term stability of the preparations, encapsulated L. leonurus solid extracts was stored in sealed standard plastic containers at four conditions: (A), room temperature of 24 ˚C ± 5 ˚C; (B), fixed temperature of 30˚C ± 5 ˚C and (C), elevated temperature of 40˚C ± 5 ˚C for 6 months, and (D), accelerated stability test conditions of 40˚C ± 5 ˚C / 75 % RH for 4 weeks. Samples of the stored encapsulated preparations were collected periodically and assessed for changes in organoleptic properties, TPC, TFC, antioxidant activity levels and marker compound (i.e. marrubiin and leonurine) levels. The latter was determined by validated HPLC assay. Yields of 19.9, 12.82 and 10.7 % of FDAE, Aq EtOH extract and calcium alginate FDAE beads were obtained, respectively. Physically the calcium alginate beads contained less moisture (1.86 %) than the FDAE (3.77 %) and Aq EtOH (2.91 %). Chemically the FDAE, Aq EtOH extract and calcium alginate FDAE beads respectively had appreciable and similar TPC (i.e.7.86, 7.52 &, 6.94 mg GAE/g; p > 0.05; Anova) and TFC (i.e. 4.30, 4.47 & 3.67 mg QE/g; p > 0.05; Anova) levels, but variable amounts of marrubiin (i.e. 22.5, 17.5, and 0.4 ug/mg plant extract) and leonurine (i.e. 2.0, 1.4 and 0.7 ug/mg plant extract), respectively. The antioxidant activity levels were also different i.e. EC50 values of 7.71, 6.66 and 11.53 mg/mL (student t-test p-value of < 0.0001; ANOVA-test; p< 0.05) for the FDAE, Aq EtOH extract and calcium alginate FDAE beads, respectively. During storage (i.e. stability study) the L. leonurus solid extracts generally remained physically unaffected by temperature (i.e. no significant change in organoleptic features), but when exposed to humidity the FDAE and Aq EtOH extracts showed clear signs of physical degradation i.e. changed from being flaky powders to sticky melted masses, while the calcium alginate beads remained unchanged. Within 1 month storage at RT, 30 °C, 40 °C and 1 week at 40 °C / 75 % RH the TPC of the encapsulated FDAE decreased significantly by 61, 60, 58 and 52 %, respectively, that for the encapsulated Aq EtOH extract by 61, 54, 46 and 50 %, respectively, and for calcium alginate FDAE beads by 66, 71, 59 and 57 %, respectively. Using TPC as a stability parameter all three encapsulated extracts had very short shelf-lives ranging from 1.24 weeks (0.31 months) to 3.72 weeks (0.93 months). Under the same conditions and storage periods (i.e. 1 month & 1 week) the TFC of the encapsulated FDAE decreased significantly by 25, 25, 29 and 66 %, respectively, for encapsulated Aq EtOH extract by 26, 26, 23 and 70 %, respectively, and the calcium alginate FDAE beads by 55, 55, 52 and 64 %, respectively. The results obtained for TFC was thus similar to that obtained for the TPC data. Based on the TFC data all three encapsulated extracts had very short shelf-lives ranging, from 1.56 weeks (0.39 months) to 6.76 weeks (1.69 months). Under the same conditions and storage periods (i.e. 1 month & 1 week) as that used to determine TPC and TFC, the antioxidant activity of the extracts changed little, i.e. decreased by 0.2, 0.1, 0.8 and 2 %, respectively for FDAE, by 0.7 %, 1 %, 0.1 % and 5.3 %, respectively for the Aq EtOH and by 2, 2, 1.4 and 0.8 %, respectively for the calcium alginate FDAE beads. Moreover, based on antioxidant activity, all three encapsulated extracts had relatively long shelf-lives ranging from 15.6 weeks (3.9 months) to 22.4 weeks (5.6 months). Finally, the determination of the stability of the encapsulated L. leonurus extracts stored under stress conditions (i.e. 40 °C / 75 % RH) and based on marker compound levels was unresolved. Between the time of extract preparation and characterisation until start of the stability study the marrubiin levels in the FDAE, Aq. ETOH and calcium beads had decreased from 22.5, 17.5, and 0.4 ug/mg plant extract, respectively, to 0.30, 0.11, 0.30 μg/mg, respectively, and the leonurine levels from 2.0, 1.4 and 0.7 to 0.46, 0.38 and 0.09 μg/mg, respectively and was too low to conduct a meaningful stability study with the developed validated assay. Overall, all three the encapsulated L. leonurus solid extracts studied were clearly very unstable and did not have suitable long-term storage stability. The modification of the freeze-dried aqueous extract of L. leonurus into a calcium alginate bead form seemed to combat physical instability but did not improve the chemical instability of the aqueous extract. It is therefore recommended that the addition of excipients or other post extract modification (e.g. production of phytosomes) be explored to combat the hygroscopicity of L. leonurus FDAE and ultimately improve its overall product stability.

Magister Pharmaceuticae - MPharm / Leonotis leonurus (L. leonurus) and Artemisia afra (A. afra) are two of the most commonly used medicinal plants in South Africa traditionally advocated for use in asthma. However, proper scientific studies to validate these claimed uses are lacking and little is known about the mechanisms for this effect. These plants contain flavonoids, which are reported to have smooth muscle relaxant activity and may be responsible for the activity of these two plants. The objectives of this study were to: (1) determine and compare the flavonoid profiles and levels in A. afra and L. leonurus, (2) compare the respiratory smooth muscle relaxant effects of freeze-dried aqueous extracts of A. afra and L. leonurus and (3) investigate whether K⁺ - channel activation (i.e. KATP channel) is one possible mechanism of action that can explain the effect obtained in traditional use of these two plants. It was hypothesized that: (1) the flavonoid levels and profile of A. afra would be greater than the flavonoid levels and profile of L. leonurus, (2) A. afra would have a more potent respiratory muscle relaxant effect than L. leonurus and (3) A. afra and L. leonurus will inhibit K⁺ - induced contractions in a superior manner than carbachol and histamine - induced contractions. To realize these objectives, freeze-dried aqueous extracts (FDAE) of the dried leaves of the two plants were prepared. A validated HPLC assay was developed and used to identify and determine the levels of luteolin in the plant preparations. Solutions of the plant extracts were studied in the isolated guinea-pig trachea tissue preparation in the presence of carbachol, histamine and KCL. The possible mechanism of action of the two plants was determined by cumulative log dose-response curves (LDRC) for carbachol, histamine and KCL in the absence and presence of 1, 30 and 100 mg/ml solutions of the plant extracts. The flavonoid profile of un-hydrolyzed and hydrolyzed L. leonurus was greater than that of un-hydrolyzed and hydrolyzed A. afra. The levels of free and total luteolin in A. afra FDAE (8.977 ± 0.73 μg/ml and 16.394 ± 0.884 μg/ml, respectively) were significantly (p < 0.001) higher than that in L. leonurus FDAE (0.929 ± 0.066 μg/ml and 3.093 ± 0.531 μg/ml, respectively). L. leonurus and A. afra relaxed tracheal smooth muscles contracted with histamine, KCL and carbachol in a dose dependent manner. The degree of relaxant activity of L. leonurus versus the three inducers of contraction (agonists) could be classified as KCL > carbachol > histamine, with EC₅₀ values of 9.87, 29.34 and 94.76 mg/ml, respectively. The A. afra tracheal smooth muscle relaxant activity was categorized as carbachol > histamine > KCL, with EC₅₀ values of 13.93, 15.47 and 19.88 mg/ml, respectively. Overall, A. afra which contained the higher levels of luteolin, was more potent at relaxing the guinea pig tracheal smooth muscle than L. leonurus. Collectively, the results confirm that aqueous solutions of A. afra and L. leonurus as used in local traditional practice have potent but different degrees of bronchodilator activities that could be useful in the treatment of asthma, and that these actions may be related to each plant's luteolin (or flavonoid) levels. Moreover it is very unlikely that KATP channels are primarily responsible for the actions of A. afra and L. leonurus, but rather that more than one mechanism of action is involved in the tracheal smooth muscle relaxant effects of these two plants. / National Research Foundation

The Government of Ontario plans to ban the land application of untreated septage; however, most town wastewater treatment plants do not have the capacity to accept septage. A combined reed bed – freezing bed technology has been successfully developed to dewater and treat septage. Lab column studies established that freeze-thaw conditioning can restore drainage in clogged sand drying beds dosed with common biological sludges and that septage can be dosed at 10 cm/week for 2.5-5.0 months before clogging is observed. Pilot studies showed that freezing beds can operate without the need for a cover with the applied sludge effectively melting any snow cover in regions with moderate snowfall. Septage freezing was successfully modelled following an accepted model for ice formation on water bodies while septage thawing was modelled using a regression analysis with initial frozen depth and precipitation found to be insignificant and degree days of warming controlling the rate of thawing. Model results were utilized to produce a freezing bed design loading map for North America based on temperature normals. Field scale planted and unplanted reed bed – freezing bed systems were constructed and tested with varying hydraulic loading rates (1.9-5.9 m/y) and solid loading rates (43-144 kg/m2/y) over a 5 year period resulting in a recommended design hydraulic loading rate of 2.9 m/y or 75 kg/m2/y. Drainage rates doubled after freeze-thaw conditioning compared to during the growing season, suggesting that freeze-thaw conditioning restores filter hydraulic conductivity. No effect of solid loading rate, planted versus unplanted filters and 7 versus 21 d dosing cycles on filter drainage was observed; however, drainage varied significantly with hydraulic loading rate. The filters separated almost all contaminants with filtrate equivalent to a low-strength domestic wastewater which can be easily treated in any municipal or decentralized wastewater system. The dewatered sludge cake had similar nutrient and solid content to a solid dairy manure and met biosolid land application standards in terms of metals and pathogens. The combined reed bed-freezing bed technology can provide a low-cost solution for the treatment and reuse of septage in cold-climate regions.

In this study, the freeze-thaw performance and other engineering properties of different cementitious mixtures containing Type I/II portland cement, Type IL (10) portland Limestone cement (PLC) and Coarse Ground cement (CG-P) with or without partial replacement of fly ash (Class F) were examined. The goal was to develop a concrete mixture with better or similar freeze-thaw durability without adversely affecting other engineering properties of concrete. Crucial engineering properties reviewed include compressive strength, splitting tensile strength, workability, the degree of hydration, setting time, shrinkage and resistivity. The study was divided into two parts, one consisting of mechanical testing of engineering properties including the freeze-thaw test. The second part consisted of microstructure study which involved detection and quantification of micro-cracks/defects using μ-CT and fluorescence microscopy. The results showed that the portland limestone cement in combination with fly ash demonstrated better or similar durability in comparison to the conventional portland cement concrete mixtures.

Charles University, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical Technology Consultant: Doc. PharmDr. Zdeňka Šklubalová, Ph.D. Student: Eliška Macáková Title of Thesis: Formulation of freeze dried tablets for oromucosal administration of peptides Freeze-drying is one out of the important methods for stabilization of active substances, particularly peptides, in pharmacy. The formulation of freeze-dried buccal/sublingual tablets for administration of peptides into the oral cavity is the main target of this thesis. The aim is to propose the combination of appropriate excipients and their concentration to achieve the suitable organoleptic properties and disintegration time of the product cake. The measurement of pH, osmolality, the thermal properties of substances, as well as the evaluation of mechanical quality of tablets and their disintegration were used. In conclusion, the combination of excipients for the composition of matrix for the futher development.