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Bacterial Utilization of Volatile Substances Produced by Streptomyces LavendulaeGray, James Howard 08 1900 (has links)
The purpose of this investigation is to attempt to learn something of the biochemical ecology of volatile substances produced by actinomycetes.
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Low temperature oxidation of volatile organic compounds using gold-based catalystsKwenda, Ellen 13 September 2011 (has links)
MSc, School of Chemistry, Faculty of Science, University of the Witwatersrand, 2011 / In this work, a detailed study of the evaluation of gold-based catalysts supported on
manganese oxides for the oxidation of volatile organic compounds (VOCs) has been
undertaken. Model catalysts were prepared by deposition-precipitation methods to
establish the effect of the support on the catalytic activity of the gold catalysts. The catalysts
were characterised by X-ray diffraction, transmission electron microscopy, N2–physisorption
measurements and temperature programmed reduction techniques. The activity of the
catalysts for VOC oxidation reactions were tested in a continuous flow fix bed glass reactor.
The products were analysed by GC/TCD and GC/FID.
The catalysts Au/TiO2, Au/Al2O3, Au/ZnO and Au/MnO2 were used for the VOC oxidation
reaction. 2-propanol, 2-butanol and toluene were used as VOCs for the study. These were
chosen because they are important indoor pollutants given their wide laboratory use and
high volatility. Toluene was found to be the most difficult to oxidise, followed by 2-propanol.
The effect of calcination temperature and preparation procedure was evaluated for the
gold/manganese oxide catalysts. Au/b-MnO2 catalysts prepared by deposition-precipitation
showed some catalytic performance which was less than the performance shown by
Au/MnOx, prepared by co-precipitation. g-MnO2 proved to be more efficient in the oxidation
of 2-propanol than pyrosulite phase MnO2. The addition of gold to any metal oxide support
was found to enhance the oxidation of VOCs. Gold-based catalysts were more active than
the Ce/MnO2 catalyst.
Catalytic tests showed that Au/CeO2 was the superior catalyst for the total oxidation of
toluene, 2-propanol and 2-butanol. Ceria is a highly reducible oxide and the formation of
gold–ceria interactions produced an even more easily reduced material.
University of the Witwatersrand, Johannesburg ii
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On the removal of odours and volatile organic compounds from gas streams using adsorption and electrochemical regenerationConti-Ramsden, Michael January 2012 (has links)
Adsorption combined with aqueous phase electrochemical regeneration has been shown by researchers at The University of Manchester (UoM) to offer an alternative approach to the removal of organics from waters and wastewater's. The process, based on a regenerable graphite intercalation compound (GIC) adsorbent, produces no secondary waste, is energy efficient and chemical free. A company, Arvia Technology Ltd., was set up in 2007 to commercialise the technology. As part of a growth and development strategy Arvia investigated other possible applications of the technology and found that odour removal from gas streams might be a good fit with technology features. This Engineering Doctorate (EngD) was a direct investigation into both this technology fit and into the market opportunity for technologies treating odours and volatile organic compounds (VOCs) in gas streams. The research conducted demonstrated that the technology in its different applied forms had certain process drawbacks. Where mass transfer, adsorption and regeneration were combined in a single unit, enhanced transfer as a result of higher pollutant Henry's coefficient was offset by lower adsorbate affinity which varied with hydrophobicity. This relation between affinity and hydrophobicity was different for oxygen functionalised aromatic molecules than for the aliphatic molecules studied. Where adsorption occurred in the gaseous phase and regeneration in the aqueous phase, disadvantages such as short adsorbent packed bed lifetimes and lower current efficiencies of oxidation as a result of adsorbate desorption were shown to be an issue. When the above process challenges were set against the challenging market environment and relatively small market opportunity (approx. £52 million in Europe, 2012) it was difficult to recommend further broad research into the technology. However it was concluded that the concept might still be usefully applied to odour and VOC abatement and that further work should focus on a two phase system with a gas phase adsorbent regeneration technique. The relation observed between adsorbate affinity, hydrophobicity and structure allowed the demonstration of the preferential removal of phenol from solutions containing significantly higher concentrations of aliphatic molecules. This finding is considered the most important project output as it highlights an opportunity to develop Arvia's water treatment technology into a targeted water treatment system for the removal of specific, industrially important, organic contaminants.
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Atmospheric Hydrocarbon AnalysisHan, Dawei 09 December 1993 (has links)
This treatise studied two correlated important issues in atmospheric chemistry: real-time monitoring of ambient air and removal mechanisms of atmospheric hydrocarbons. An analytical system was designed for the purpose of identification and measurement of sub-ppb level hydrocarbons of different reactivities in air samples. This analytical system was then applied to a series of smog-chamber studies which simulated the removal of reactive hydrocarbons from the atmosphere by reaction with hydroxyl radicals. Six representative atmospheric hydrocarbons ( hexane, octane, toluene, m-xylene, a-xylene and mesitylene) were selected for these experiments. The experimental data indicated that the decay of atmospheric hydrocarbons under laboratory conditions is entirely due to reaction with hydroxyl radicals. The conclusion drawn from a time-resolved plume study that aromatic molecules decay much faster than could be accounted for solely by reaction with hydroxyl radicals was not verified; this indicates a difference between laboratory study and the study in the real atmosphere, and some physical factors besides chemical mechanism might take a more significant role in removing aromatics faster from the atmosphere.
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The Investigation of Human Scent from Epileptic Patients for the Identification of a Biomarker for Epileptic SeizuresDavis, Philip R.N. 31 October 2017 (has links)
Studies have shown that some canines have the ability to predict seizures in people with epilepsy, and that canines can be trained to recognize changes in humans before an epileptic seizure and make these predictions. It is not known with any certainty to what the canines are alerting. However, canines’ exceptional sense of smell and their ability to discriminate human scent is well established. Therefore, it is possible that the canines could be responding to an olfactory cue, such as the release of some volatile organic compounds (VOCs) prior to the onset of a seizure.
Individuals release a wide array of VOCs, both odorous and non-odorous, from their bodies. The odorous VOCs collectively make up human scent and a number of these VOCs have been identified as biomarkers of different diseases. Evidence suggests that canines can perceive these biomarkers, leading to early detection of underlying physical ailments before individuals are aware of their own symptoms.
The main purpose of this study was to use headspace solid phase microextraction (HS-SPME) with gas chromatography-mass spectrometry (GC-MS) to analyze hand odor, saliva and breath samples from epileptic with and without seizure activity to determine if the human scent profiles resulting from a seizure event differs from the scent profiles in the absence of seizure activity. the HS-SPME-GC-MS method was also used to analyze and compare hand odor, saliva and breath samples of healthy individuals and epilepsy patients to determine if the profiles can be differentiated.
Comparison of the VOCs in each specimen from healthy individuals and epileptic patients revealed compounds that could be used as potential biomarkers to differentiate between healthy and epileptic individuals. Comparison of the VOCs in each specimen from epileptic patients with and without seizure activity revealed compounds that could be used as potential biomarkers for epileptic seizures. Finally, canine trials were used to verify that these compounds are indeed biomarkers.
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Development of Gas Chromatography/Electrospray Ionization Mass Spectrometry for the Characterization of Volatile Organic MixtureChen, Jiun-Chi 13 July 2010 (has links)
none
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An energy efficient cache design using spin torque transfer (STT) RAMRasquinha, Mitchelle 23 August 2011 (has links)
The advent of many core architectures has coincided with the energy and power
limited design of modern processors. Projections for main memory clearly show
widening of the processor-memory gap. Cache capacity increased to help reduce
this gap will lead to increased energy and area usage and due to small growth in
die size, impede performance scaling that has accompanied Moore's Law to date.
Among the dominant sources of energy consumption is the on-chip memory hierar-
chy, specically the L2 cache and the Last Level Cache (LLC). This work explores
the use of a novel non-volatile memory technology - Spin Torque Transfer RAM
(STT RAM)" for the design of the L2/LLC caches. While STTRAM is a promising
memory technology, it has some limitations, particularly in terms of write energy and
write latencies. The main objectives of this thesis is to use a novel cell design for a
non-volatile 1T1MTJ cell and demonstrate its use at the L2 and LLC cache levels
with architectural optimizations to maximize energy reduction. The proposed cache
hierarchy dissipates significantly lesser energy (both leakage and dynamic) and uses
less area in comparison to a conventional SRAM based cache designs.
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Molecular structures and pulsed discharge emission studies of volatile organic compound derivatives /Osthoff, Ashley, January 2009 (has links) (PDF)
Thesis (M.S.)--Eastern Illinois University, 2009. / Includes bibliographical references.
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Control and characterization of biomass activity and distribution in vapor-phase bioreactors for VOC removal /Song, Ji-hyeon, January 2001 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 212-220). Available also in a digital version from Dissertation Abstracts.
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Development of acillary techniques for chromatographic analysis of trace organic pollutants in environmental samples吳祖成, Wu, Zucheng. January 1995 (has links)
published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy
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