This research presents a critical evaluation of chitin- and chitosan-based materials as innovative treatment alternatives for water contaminated with insensitive munitions (IMs) compounds. Specifically, chitin, chitosan, amineunctionalized chitin (AFC) were evaluated for adsorptive removal of these compounds. Cellulose and cellulose triacetate were evaluated for adsorptive performance for comparison. Chitosan-graphene oxide (CSGO) composite membranes were evaluated for removal via adsorption and filtration and compared against nanofiltration and reverse osmosis membranes in the current market. Insensitive munitions evaluated include nitrotriazolone (NTO), nitroguanidine (NQ), and 2,4-dinitroanisole (DNAN); 2,4,6-trinitrotoluene (TNT) was also studied as a traditional munition for comparison. AFC is an effective adsorbent for NTO, DNAN, and TNT. Cellulose triacetate was the only commercially available biopolymer adsorbent effective at removing munitions compounds from solution; only DNAN and TNT were removed. CSGO membranes effectively removed NTO, DNAN, and TNT, but removal performance degraded with time. Overall, this research shows that the materials studied are viable options for removing IM and traditional munitions from water.

No description available.

Organophosphates (OP) such as malathion are organic derivatives of phosphoric acid with broad use in everyday life throughout the world, especially as insecticides. Lead particles can accumulate in soil and from there leach into our water supplies. Interaction with the environment offers opportunities for multiple exposures to combinations of different toxicants (such as lead and malathion). Thus, it is important to assess effects that these compounds exert not only on the nervous system, but also on the blood-brain barrier (BBB). The BBB consists of specialized endothelial cells that form the vasculature of the brain; it regulates passage of nutrients, while preventing potentially damaging substances from entering the brain. The main feature of the BBB is the presence of tight junctions between cells, which provide the BBB with its low permeability. The work presented in this dissertation tests the hypothesis that lead and malathion disrupt BBB integrity by affecting tight junctions of the BBB. The hypothesis suggests that disruptions involve changes in protein levels and gene expression as well as activation of transient receptor potential canonical channels (TRPC) that in turn increase intracellular calcium levels affecting tight junction structure. The hypothesis was tested by assessing lead-malathion interactions in an in vitro BBB model. This model was constructed with rat astrocytes and rat brain endothelial cells (RBE4). Assessments of cell toxicity in response to different concentrations of the neurotoxicants tested showed that concentrations between 10-5 µM and 10-6 µM were ideal to assess combinations of neurotoxicants. In general, protein levels of occludin, claudin 5, ZO1, and ZO2 decreased at all times, however, qPCR analysis of gene expression for all the proteins did not correlate with the assessments on protein levels. TRPC channel protein levels increased in response to neurotoxicant insult, which correlated with results for gene expression. This study suggests that at least one of the mechanisms that neurotoxicants lead and malathion utilize to disrupt permeability of the BBB is by affecting tight junction structure. This effect could be regulated by increases in gene expression of TRPC1 and TRPC4 that are associated with increases in the number of TRPC channels on the membrane of endothelial cells of the cerebral microvasculature. / Ph. D.

The aims of the first study were to determine the effects of early weaning followed by a period of high-grain feeding on signaling protein phosphorylation in muscle and on acetate clearance in growing steers.  Twelve Angus X Simmental steers were used in the study.  Six steers were weaned early (EW) and fed a high-gain diet for 148 d and the remainder were weaned at the normal age (NW).  Longissimus muscle tissue biopsies were collected to determine total and phosphorylated forms of AMP kinase and downstream proteins of the mTOR signaling pathway.   Of the 12, 8 steers were used to assess acetate clearance at different age points.  During early grain feeding, phosphorylated:total ratios of rpS6 and S6K1 were greater in EW steers and they had lower acetate clearance rates and greater synthesis rates.   The objectives of second study were to assess the effects of early grain feeding on acetate and glucose turnover rates, palmitate synthesis, and on acetate and glucose preference by subcutaneous, intramuscular and visceral adipose tissues in finishing steers.  Sixteen Angus x Simmental steers were infused continuously with [2H3] acetate (n = 8) or [U-13C6] glucose (n = 8), over a 12 h period immediately prior to harvest.  Plasma acetate and glucose enrichment, and palmitate enrichment in different adipose tissue locations were determined.  There were no treatment effects on acetate or glucose turnover rates or palmitate fractional synthesis rates (FSR).  Acetate turnover and palmitate FSR from acetate were greater than the corresponding rates from glucose.  There were no differences in preference for acetate or glucose among the fat depots. In conclusion, phosphorylation ratios of signaling proteins were not affected treatment.  Acetate clearance increased when steers were heavier and older.  Thus older calves are able to clear more acetate per unit of time and body mass than younger calves reflective of an enhanced ability to utilize the substrate.  There were no differences in preference for acetate and glucose among the major fat depots.  Thus diets leading to high glucose supply will not preferentially direct energy storage to intramuscular stores. / Ph. D.

The dielectric dispersion of poly(vinyl acetate) solutions was studied in an attempt to relate this behavior to the chemical nature of the material. The bridge method was employed in which capacitance measurement of solutions were made over a frequency range of 400 cycles to 500 kilocycles. The results of these experiments indicate that a vinyl type material possesses greater flexibility than cellulose derivatives in solution and, thus, the magnitude of capacitance changes over a frequency range is considerably reduced. Because of the very small changes in capacitance, reproducible results are difficult to obtain and definite conclusions as to the relation of dispersion to molecular weight are impossible. Dielectric dispersion studies were made on solutions of poly(vinyl acetate) in dioxane, ethylene chloride and acetone. / Master of Science

In this study, surface plasmon resonance (SPR) and quartz crystal microbalance with dissipation monitoring (QCM-D) were combined to investigate the adsorption behavior of two platelet adhesion-related blood proteins, human serum albumin (HSA) and human serum fibrinogen (HSF), on two polysaccharide materials used for hemodialysis membrane applications: regenerated cellulose and cellulose acetate. The study aims to provide insight into the design of novel hemocompatible polysaccharide materials. Information such as real-time adsorption curves, adsorbed amounts, and water contents of the protein layers were obtained and analyzed. The results suggested 1) monolayer adsorption of HSA on both cellulose and cellulose acetate, possibly with different HSA conformations; 2) a multilayer of HSF or some degree of end-on adsorption on both surfaces. The study of HSA adsorption onto cellulose acetate surfaces with different degrees of substitution indicated that the change in content of acetyl groups may not be the main factor governing the adsorbed HSA amount but may affect the conformation of adsorbed HSA molecules. / Master of Science

The speed of a chemical reaction is important in determining the efficiency of many industrial chemical reactions. In organic reactions particularly, when there is the possibility of several reactions going on simultaneously, that reaction which is fastest is the one that predominates and often affects the economics of the process. The object of this investigation was to determine the effect of ultrasonic irradiation on the specific reaction rate of the hydrolysis of an aqueous solution of ethyl acetate in the presence of hydrochloric acid as the catalyst. The commercially obtained ultrasonic generator was limited to four frequencies - namely, 400, 700, 1000, and 1500 kilocycles. Two thousand volts plate voltage could be applied to the quartz crystal plates provided the plate current did not exceed 360 milliamperes. A special pyrex glass reactor was designed and constructed in order that isothermal conditions could be maintained within the boundary of the reactor. The period of time the reaction mixture was subjected to ultrasonic irradiation was arbitrarily set at 10 minutes for a given power and frequency at 19 ± 0.1°C and 30 ± 0.1°C respectively. The tests were then repeated using a 20 minute period of irradiation. Individual mixtures were respectively irradiated at 0, 500, 1000, and 1500 volts plate voltage. The composition and volume of the mixture irradiated was 100 ml of 1.9904 N hydrochloric acid, 90 ml of distilled water free from carbon dioxide, and 10 ml of ethyl acetate making a total volume of 200 ml. The chemical reaction assumed for the investigation was CH₃COOC₂H₅ + H₂O + H⁺ ⇋ CH₃COOH + C₂H₅OH + H⁺ The course of the reaction was followed in such a way that the concentrations of the reacting substances were not disturbed. Samples of the mixture were drawn off at intervals and titrated with sodium hydroxide using phenolphthalein as the indicator. Calculations were based on the difference of the titration at any time t in minutes and the titration at the end of 24 hours. When the reaction was completed, this difference was a measure of the concentration of ethyl acetate remaining unchanged or unhydrolyzed at time t. Each molecule of ethyl acetate that hydrolyzed produced one molecule of acetic acid, and the increase in acidity was a direct measure of the amount of ethyl acetate that had reacted. The amount of hydrochloric acid remained unchanged throughout the experiment. The concentrations of ethyl acetate calculated from the differences between the titration values and the final titration were arranged in tabular form. A graph was drawn on semilogarithmic paper by plotting the concentration of ethyl acetate, c, against time, t, in minutes and the best straight line through the points. Using the equation, - log c_A (k / 2,303) t+ constant, the specific reaction rate, k, was calculated by multiplying the slope of the line by 2.303. The activation energy, E, was calculated from the values of k at 19 ± 0.1°C and 30 ± 0.1°C using the equation, E = [2.303 log₁₀ k₂/k x R x T₁ x T₂] / [T₂ - T₁] where k₁ = specific reaction rate at 19 ± 0.1°C k₂ = specific reaction rate at 30 ± 0.1°C R = Constant T₁ = Absolute temperature for 19 ± 0.1°C T₂ = Absolute temperature for 30 ± 0.1°C The results of this investigation showed that the specific reaction rates were increased by ultrasonic irradiation of 400, 700, 1000, 1500 kc in the order of five percent for 20 minutes irradiation over the rates for 10 minutes irradiation. / Ph. D.

The objective of this thesis was to further develop the polymer composite system consisting of cellulose acetate butyrate (CAB) and high modulus, continuous, regenerated cellulose fiber (lyocell). Of particular concern were both the interfacial adhesion between the fiber and matrix and the consolidation process in the manufacture of these composite materials. Interfacial adhesion was found to be substantial due to the relative lack of the fiber pull-out phenomenon observed after tensile failure in the unmodified fiber composites. This result was then supported in the second study in which similar unmodified fiber composites experienced very little fiber pull out with evidence of a large amount of cohesive failure of the matrix accompanied by matrix particles adhering to the fiber surfaces. Void volume formation was mitigated to a small extent by the use of optimal consolidation conditions. Composites formed at moderate temperature (200 °C), low consolidation pressure (11.8 p.s.i.) and high consolidation time (13 min.) were found to have the lowest void volume formation of ca. 2.8 %. These composites were generally found to have the highest interfacial shear strength, ca. 16 MPa. A tensile modulus of 22 GPa and an ultimate strength of 246 MPa was obtained for this composite having a fiber volume content of ca. 62 %. / Master of Science

The efficacy of a novel carbohydrate extraction procedure was investigated with methylation analysis and alditol acetate method by Gas Chromatography-Mass Spectrometry. A published extraction procedure for β-glucans was compared to one developed in house. Both procedures gave a dominant glucose peak in the Gas chromatogram indicative of successful β-glucan isolation. Further linkage studies showed four linkage positions for β-glucans isolated with the published method; terminal, 1,3-linkage, 1,6-linkage and 1,3,6-linkage, while β-glucans isolated using the new method showed six linkage positions; terminal, 1,3-linkage, 1,6-linkage, 1,4-linkage, 1,2,3-linkage and 1,3,6-linkage. Diminishing β-glucan linkage peaks in the chromatogram for the published method indicated structure degradation. The results for mannan isolated with 50 mM base gave mannose as a dominant component compared to mannan isolated with 50 mM acid. Base extracted mannan also indicated a good yield of mannan in hyphal form of Candida albicans. This has not been reported with other published isolation methods.

Thesis (PhD)--Stellenbosch University, 2012. / Bibliography / ENGLISH ABSTRACT: Most individuals latently infected with Mycobacterium tuberculosis (Mtb) contain the infection by a balance of effector and regulatory immune responses. However, this balance can be influenced by steroid hormones such as glucocorticoids (GCs), which are known to increase the risk of reactivation of TB. The contraceptive medroxyprogesterone acetate (MPA), which also possesses selective glucocorticoid activity, is widely used in developing countries with approximately 60% of women on contraceptives using MPA in our study cohort. Therefore, our aim was to investigate the effect of this hormone on protective immune responses to BCG in HIV negative household contacts of active TB patients. When PBMCs of TB household contacts were stimulated with BCG in the presence of 10 μM MPA; this hormone displayed both glucocorticoid as well as progestogenic properties. Similarly to cortisol, MPA suppressed antigen specific expression of a range of cytokines including IL-1α, IL-1ra, IL- 17, TNFα, IL-5 and IFNγ. Dose response curves showed that MPA can also alter expression of some cytokines at lower contraceptive doses (in the nano molar range). To assess whether this effect of MPA in vitro also occurs in women using this hormone as contraceptive the PBMCs of MPA users and controls were stimulated with BCG and the levels of up to 29 different cytokines measured by luminex analysis. PBMCs of MPA users produced significantly lower levels of cytokines involved in immune responses against Mtb such as IL-12p40, IL-1α, IL-10, IL-13 and G-CSF, which corresponds with lower numbers of circulating monocytes observed in these women. These findings warrant further investigation and clinical trials should investigate the risk of progression from latent to active TB disease in women using this contraceptive. These trials, however, require a large number of participants and are prohibitively expensive; therefore it was decided to setup an Mtb/MPA mouse model to determine the effect of MPA on the disease outcome. BALB/c and C57BL/6 mice were injected with a weekly dose of one mg MPA or PBS and infected with 30 colony forming units of Mtb H37Rv one week after commencing the hormonal treatment. Both strains were included to establish which strain best represents the human model. Three and eight weeks post infection the MPA treated C57BL/6 mice had a significantly higher bacterial load in their lungs compared to untreated mice, whereas no difference was found in the bacterial loads of the BALB/c mice. MPA treated C57BL/6 mice had significantly lower serum levels of IL-10 and G-CSF and MPA treated BALB/c mice lower serum levels of IFNγ, when compared to untreated mice. Furthermore, cells isolated from the MLNs of MPA treated C57BL/6 mice, produced significantly less TNFα, significantly more IP-10 and less IL-10 in response to PPD, while MLN cells of MPA treated BALB/c mice produced significantly less IFNγ, IL-2, IL-17, GM-CSF and MCP-1. Data of the C57BL/6 mouse strain correlated with our human data and can it therefore be said that the C57BL/6 mouse strain, together with the serum concentration of MPA used in these experiments, is a good model to determine the effect of MPA in the context of a low dose Mtb infection. To conclude MPA use could therefore alter susceptibility to TB, TB disease severity as well as change the efficacy of new BCG-based vaccines, especially prime-boost vaccine strategies which may be administered to adult of adolescent women in the future. / AFRIKAANSE OPSOMMING: Die meeste mense wat latent met Mycobacterium tuberculosis (Mtb) geïnfekteer is, hou die infeksie onder beheer deur ʼn balans te handhaaf tussen effektor en regulatoriese immuunresponse. Hierdie balans kan egter beïnvloed word deur steroïedhormone soos glukokortikoïede (GCs), wat bewys is om die risiko van die heraktivering van TB te verhoog. Die voorbehoedmiddel medroksiprogesteroon-asetaat (MPA), wat ook selektiewe glukokortikoïed-aktiwiteit toon, word wyd gebruik in ontwikkelende lande en omtrent 60% van die vrouens in ons studie-bevolking wat voorbehoedmiddels gebruik, gebruik MPA. Om dié rede wou ons die effek van hierdie hormoon op die beskermende immuun-response teenoor M.bovis Bacilli Calmette-Guérin (BCG) in HIV negatiewe huishoudelike kontakte (HHKe) van pasiënte met aktiewe TB ondersoek. Ons het gevind dat wanneer perifere bloed mononukleêre selle (PBMSe) met BCG gestimuleer word in die teenwoordigheid van 10 μM MPA, hierdie hormoon beide glukokortikoïede en progesterogeniese eienskappe toon. Soos kortisol het MPA die antigeenspesifieke-uitdrukking van ʼn reeks sitokiene, insluitend IL-1α, IL-1ra, IL-17, TNFα, IL-5 en IFNγ, onderdruk. Respons kurwes wat verskillende konsentrasies van hormoon insluit, het getoon dat MPA ook by laer (nano-molare) dosisse die uitdrukking van sommige sitokiene kon verander. Om te bepaal of hierdie in vitro effek van MPA ook in vrouens wat MPA as voorbehoedmiddel gebruik voorkom, het ons PBMSe van MPA-gebruikers and kontroles met BCG gestimuleer en die vlakke van tot 29 verskillende sitokiene met behulp van Luminexanalise gemeet. PBMSe van MPA-gebruikers produseer beduidende laer vlakke van IL-12p40, IL-1α, IL- 10, IL-13 en G-CSF, wat elk in imuunafweerreaksies teen Mtb betrokke is. Die afname in dié sitokiene het gepaard gegaan met laer hoeveelhede sirkulerende monosiete. Ons resultate regverdig verdere ondersoeke en kliniese proewe behoort die risiko van progressie vanaf latente tot aktiewe TB in vrouens wat hierdie voorbehoedmiddel gebruik te bepaal. Sulke proewe vereis egter groot getalle deelnemers en is skrikwekkend duur, om die rede het ons besluit om ʼn Mtb/MPA muis-model op te stel om sodoende die algehele effek van MPA op die uitkoms van die siekte te bepaal. BALB/c en C57BL/6 muise is met ʼn weeklikse dosis van een mg MPA of sout oplossing ingespuit en een week na die aanvang van die hormoon behandeling met 30 kolonie-vormende eenhede Mtb H37Rv geïnfekteer. Beide muis tipes was ingesluit om sodoende te bepaal watter tipe die mens data die beste verteenwoordig. Drie en agt weke na die infeksie het die MPA-behandelde C57BL/6 muise ‘n beduidende hoër bakteriële lading in hul longe gehad as die onbehandelde muise, maar was daar geen verskil in die bakteriële ladings in die longe van die BALB/c muise nie. MPA-behandelde C57BL/6 muise het beduidende laer serumvlakke van IL-10 en G-CSF gehad, terwyl MPA-behandelde BALB/c muise laer serumvlakke van IFNγ gehad het. Verder het ons gevind dat die geisoleerde limfosiete van MPA-behandelde C57BL/6 muise beduidend minder TNFα, beduidend meer IP-10 en minder IL-10 geproduseer het na stimulasie met PPD, terwyl die limfosiete van MPA-behandelde BALB/c muise beduidend minder IFNγ, IL-2, IL-17, GM-CSF en MCP-1 geproduseer het. Data van die C57BL/6 muise stem ooreen met die van ons mens studie en ons kan dus vermeld dat die C57BL/6 muise, tesame met die spesifieke serumkonsentrasie van MPA wat gebruik is, ʼn goeie model is om die effek van MPA in die konteks van ʼn lae-dosis Mtb-infeksie te bestudeer. MPA gebruik kan dus die vatbaarheid vir TB, asook die erns van die siekte verander en kan ook die effektiwiteit van nuwe BCG-gebaseerde entstowwe, veral prima-hupstoot enstowwe, wat moontlik in die nabye toekoms vir volwasse en adolessente vroue toegedien kan word, verander.