No description available.

In this study, a two-bed electrically-heated regenerative catalytic oxidizer (RCO) was used to test the destruction characteristics in burning toluene-borne air streams. The RCO contained two 0.152 m¡Ñ0.14 m¡Ñ1.0 m (L ¡Ñ W ¡Ñ H) beds, both packed with gravel particles with an average diameter of around 0.0111 m and a height of up to 0.875 m with a void fraction of 0.42 in the packed section. In addition, in each column catalytic particles with an average diameter of around 0.008 m were packed over the gravel particles to a height of 0.125 m. Gas temperature rise and the gas pressure drop over the beds were also studied. Experimental results reveal that, with a valve shifting time (ts) of 1.5 min, superficial gas velocities (Ug) of 0.39 and 0.86 m/s (evaluated at an influent air temperature of around 30 oC) and preset maximum destruction temperatures (TS) of 300-400 oC, only around 25% of the influent toluene (Co = 200-400 ppm) was thermally destructed with no catalyst in both beds. With the cartalyst packings and operation conditions of Ug = 0.39 m/s and Co = 200-800 ppm, destruction efficacies of around 80.9¡Ó0.8, 94.6¡Ó1.8, and 98.1¡Ó0.2 % were observed, respectively, at TS of 250, 300, and 400 oC. At Ug = 0.86 m/s and Co = 200-800 ppm, destruction efficacies of around 69.7¡Ó3.1, 93.9¡Ó1.7, and 97.8¡Ó0.4 % were observed, respectively, at TS of 250, 300, and 400 oC. It is suggested that operation conditions with Ug = 0.39-0.86 m/s (equivalent to empty-bed-residence times of 0.29-0.64 s for the gas at 30oC through the catalyst beds) and TS = 300 oC are suitable for the destruction of around 98% of the influent air with 200-800 ppm toluene. Gas temperature rises of 21 and 26 oC, respectively, were found for Ug = 0.39 and 0.86 m/s with TS = 300 oC. The Ergun equation was found to suffice in the estimation of the pressure drop when the gas flowed over the packing beds.

Regenerative oxidation is an economic and effective means of controlling volatile organic compounds (VOCs) with concentrations exceeding 1,200 mg/m3 in gas streams. Regenerative catalytic oxidizers (RCO) and regenerative thermal oxidizers are two main applications for the regenerative oxidation. However, factors influencing the performance of regenerative oxidation when treating VOCs in gas streams have seldom been addressed. Therefore, this study presents a convection-dispersion model with an effective thermal diffusivity (£\e ) as a parameter to simulate the performance of regenerative beds. To verify the effectiveness of the proposed model, a pilot-scale RCO was constructed with two 20-cm x 200-cm (ID x H) regenerative beds. Gravel was used as the thermal regenerative solid material. Experimental results indicated that the model with an £\e of 2.0-3.8 x 10-6 m2/s can be used to describe the time variation of solid temperatures with the packing height at superficial gas velocities (Ug ) of 0.080-0.382 Nm/s . Values of£\e for the bed are closer to those for the gravel solids (£\s = 1.0 x 10-6 m2/s) than for air (£\g = 54 x 10-6 m2/s). Those results demonstrate that the conductive heat transfer in the solid material in the axial direction of the bed is a major controlling factor for the performance of the RCO and the convective one is a minor factor in the present case. The above pilot RCO was then used to treat methyl ethyl ketone (MEK) and toluene, respectively, in air streams. The catalyst bed temperature was kept around 400oC and the Ug was operated at 0.234 Nm/s. This investigation measured and analyzed distributions of solid and gas temperatures with operating time and variations of VOC concentrations in the regenerative beds. The overall VOCs removal efficiency exceeded 98% for MEK of around 800 ppm as methane and 95% for toluene of around 400 ppm as methane. Degradation of MEK was believed to occur on the surface of solid material (gravel) in the temperature range of 330-400oC, which is much lower than its autoignition point, and toluene did not exhibit this phenomenon. The calculated energy conservation presents that RCO is an economic approach to treat VOCs, and it should be much further applied to industrial fields. Furthermore, based on the earlier empirical results of RCO, a series of plant scale low temperature regenerative oxidizers (LTRTOs) equipped with heating wires were constructed to treat VOC-laden gas streams. The regenerative beds were still packed with the same gravel which was applied to the above pilot RCO. Gas streams for performance tests were exhausted from manufacturing sections of varnishing, semiconductor packing, and petrochemical plants, respectively. Components of tested VOCs were comprised of several commercial solvents (e.g. ketone, toluene, iso-propanol, methanol, ethanol, formaldehyde, dimethylamine, and others). Results indicate that exceeding 98% of single or multiple VOCs with concentrations of less than 100 and increasingly to 7,000 ppm as methane would be effectively destroyed. Gas temperature variations with time at various bed depths were analyzed, and results confirm that the degradation of VOCs exists in the gravel beds at the temperatures ranging from 300 to 440oC, which are much lower than auto-ignition points of tested compounds. Moreover, the residence time for a gas stream passing through the main oxidation zone (Tg >300oC) in the regenerative beds is an essential criteria for LTRTO design and 1.0 s is recommended. These findings demonstrate that LTRTO is an effective approach to treat VOCs.

No description available.

Master of Science / Department of Clinical Sciences / James K. Roush / The objective of this study was to evaluate the effects of intraarticular dextrose prolotherapy on osteoarthritis of the elbow or stifle in dogs. This was a randomized, double-blind, placebo controlled prospective trial of intraarticular dextrose prolotherapy given at 0 and 6 weeks for relief of osteoarthritis. Dogs with unilateral lameness were evaluated by orthopedic exam, visual lameness score, Canine Brief Pain Inventory (CBPI), goniometry, and by kinetic gait analysis at 0, 6 and 12 weeks. Joint radiographs were scored at 0 and 12 weeks. Ten client-owned dogs with naturally occurring osteoarthritis of the elbow or stifle were enrolled. Initial visual lameness, age, body weight, duration of lameness, and CBPI scores did not differ between groups. Change in CBPI PS score in the prolotherapy group from week 6-12 was significantly less improved than placebo with no other significant differences in CBPI Pain Severity (PS) or Pain Interference (PI) scores between groups. There were no significant differences for range of motion or radiographic scores between groups at any time. Kinetic forces improved in prolotherapy dogs, but were not significantly different between treatment groups at any time. There were no significant benefits of intraarticular dextrose prolotherapy for treatment of osteoarthritis of the elbow and stifle in dogs in this study. Larger enrollments and more stringent inclusion criteria should be considered in future evaluations of prolotherapy.

The concerted action of ion channels and pumps establishing a resting membrane potential has been most thoroughly studied in the context of excitable cells, most notably neurons, but emerging evidences indicate that they are also involved in controlling proliferation and differentiation of nonexcitable somatic stem cells. The importance of understanding stem cell contribution to tissue formation during embryonic development, adult homeostasis, and regeneration in disease has prompted many groups to study and manipulate the membrane potential of stem cells in a variety of systems. In this paper we aimed at summarizing the current knowledge on the role of ion channels and pumps in the context of mammalian corticogenesis with particular emphasis on their contribution to the switch of neural stem cells from proliferation to differentiation and generation of more committed progenitors and neurons, whose lineage during brain development has been recently elucidated.

This dissertation's urban vision looks at the environmental issues of land, water and the health of the people of Vanderbijlpark, all of which have been affected by heavy industry. The study sets out to address the deteriorating quality of the Vaal River's water and how this is affected by the tributaries feeding into it. This dissertation will focus on the remediation and monitoring of the contaminated water through an ecosystemic approach. The programme involves the removal of heavy metals from the industrial effluent from the surrounding heavy industry that flows into the Rietspruit Canal. The potential of micro-organisms, plants and insects will be explored as elements of a natural treatment system of the contaminated water. The site identified for the remediation processes is an abandoned parcel of land - a remnant of the natural landscape after urban sprawl. The algae and wetland treatment system will run through the facility, becoming the spine for the remediation process and movement through the facility. The production of silk, its uses and by-products will be integrated to support the overall system which treats the contaminated water. The facility aims to address the community's need to express their voice on environmental and health issues by integrating a community auditorium and exhibition space. The construction and materiality is grounded in the premise that the local companies will remain supportive and collaborative in the environmental intervention in the Rietspruit Canal system, into which they contribute considerable effluent. It will also be proposed that the local companies will fund and supply various steel products for the construction of the intervention. This will form part of the company's corporate social responsibility and a way of giving back to fringe communities affected by industry. / Die stedelike visie vir hierdie verhandeling fokus op die omgewingskwessies van grond, water en die gesondheid van die mense van Vanderbijlpark wie almal geraak word deur swaar nywerhede. Die studie spreek die verswakkende kwaliteit van die Vaalrivier se water aan en hoe dit geraak word deur sytakke wat daarin vloei. Die verhandeling sal fokus op wyses waarop besoedelde water deur middel van 'n ekosistemiese benadering herstel en gemonitor kan word. Die program behels die verwydering van swaar metale uit die industri?le uitvloeisel van die omliggende swaar nywerhede wat in die Rietspruit-kanaal vloei. Die potensiaal van mikro-organismes, plante en insekte as elemente van 'n natuurlike stelsel vir die behandeling van die besoedelde water, word ondersoek. Die terrein wat geidentifiseer is vir die herstelprosesse is 'n verlate stuk grond, 'n oorblyfsel van die natuurlike landskap na stadspreiding. Die stelsel vir die behandeling van alge en vleilandhabitatte sal deur die fasiliteit loop en die ruggraat van die herstelproses vorm. Die produksie van sy en die gebruike en neweprodukte daarvan sal geintegreer word om die totale sisteem wat die besoedelde water behandel, te ondersteun. Die fasiliteit het ten doel om die behoefte van die gemeenskap om hul stemme oor omgewings- en gesondheidskwessies te verhef, aan te spreek deur die gemeenskapsamfiteater en uitstalruimte te integreer. Die konstruksie en materialiteit is gegrond op die veronderstelling dat die grootste staalnywerheid, ArcelorMittal, ondersteunend en samewerkend sal wees ten opsigte van die omgewingsingryping in die Rietspruit-kanaalsisteem, waartoe hul aansienlike uitvloeisel bydra. Daar sal ook voorgestel word dat die swaar nywerhede die befondsing asook verskeie staalprodukte vir die oprigting van die fasiliteit sal verskaf. Dit sal deel uitmaak van die maatskappy se korporatiewe sosiale verantwoordelikheid en is 'n manier om aan gemeenskappe wat deur die industrie geaffekteer word, terug te gee. / Mini Dissertation (MArch (Prof))--University of Pretoria, 2016. / Architecture / MArch (Prof) / Unrestricted

Algal blooms and the reduction of the seabed’s oxygen have a particularly negative impact on the Baltic Sea, caused by the eutrophication process. The process of eutrophication involves the gradual enrichment of a body of water, or portions of it, with minerals and nutrients, especially nitrogen and phosphorus. In Sweden, agriculture is the source of almost half of the nitrogen and phosphorus released into the environment. (Swedish Board of Agriculture 2013) As a result of eutrophication catalysed by climate change, marine biodiversity and fish stocks suffer also reducing the welfare of citizens. Around 30% of the total nitrogen inputs come from atmospheric sources, mostly combustion operations connected to shipping, road traffic, energy generation, and agriculture. (HELCOM 2017) Despite the fact that nutrient leakage has decreased in recent years, 97% of the surface of the Baltic Sea is still affected by eutrophication (HELCOM 2017). Taking this as an emergency call, research aims to investigate on how architecture can become a catalyst for environmental regeneration, resulting in a net positive outcome. The research refers to the theory of regenerative design, which has received particular attention in recent years in addressing constraints of sustainability. The design proposal aims to spatialize regenerative processes operating on different scales, from bio-material development to an urban masterplan. The research envisions a regenerative approach to the Baltic Sea by introducing a network of interventions operating on the transitional zone between agricultural fields and rivers transmitting nutrient pollution to the sea as part of its catchment basin. The design proposal integrates regenerative strategies learned from case studies and a literature review. Research speculates on how to reduce excessive nutrient enrichment in soil, water and decrease anthropogenic nutrient loading, while engaging with the local community through eco-recreation. Enlisting nature as a guide and referring to biomimicry as the model, the network of various functional zones suggests bioremediation of polluted agricultural fields. At the same time proposal providide alternative platforms for cultivation and recreational infrastructures closely related to an adjusted urban fabric applied in the territory of Umeå in Sweden.

No description available.

In this study, a two-bed electrically-heated regenerative thermal oxidizer (RTO) was used to test NOx formation characteristics from burning air-laden N, N-dimethyl formamide (DMF) and air-laden DMF mixed with methyl ethyl ketone (MEK). The RTO contained two 0.152 m ¡Ñ 0.14 m ¡Ñ 1.0 m (L ¡Ñ W ¡Ñ H) beds both packed with gravel particles of around 1.11 cm in average diameter to a height of 1.0 m, and the packed section had a void fraction of 0.416. Performances on the thermal destructions of DMF and MEK, the thermal recovery efficiency, as well as the gas pressure drop over the regenerative beds were investigated. Experimental results indicate that, with a valve shifting time (ts) of 1.5 min, gas superficial velocities (Ug) of 0.39-0.78 m/s (evaluated at an influent air temperature of around 30oC), and set maximum destruction temperatures (Tset) of 750-950 oC, there was no NOx in the effluent gas from the RTO with no DMF in the influent air. With only DMF in the influent gas, its destruction efficiencies were 96.3 (750oC), 97.4 (850oC) and 97.9 % (950oC), and increased with increasing influent DMF concentration from 100-250 ppm. Mole ratios of ¡§NOx-N formation/DMF destruction¡¨ were found to be in the range of 0.84-1.20, and the ratio decreased with increasing influent DMF concentration within the experimental range. With both DMF and MEK in the influent gas, no significant influence was found in the NOx formation ratio and the DMF destruction efficiency with influent MEK/DMF ratios of 50/100 - 1500/100 (ppm/ppm) and the set temperatures. The NOx formation ratios were in the range of 0.85-1.07. The Ergun equation was adequate for the estimation of the pressure drop for the gas flowing over the packed regenerative beds in the Ug range of 37-0.74 m/s. It was also found that the thermal recovery efficiency was decreasing with the increasing Ug and invariant with Tset.