Dissertations / Theses on the topic 'Chemical investigation'
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Porter, Joshua D. "A Chemical Investigation of Australian Winteraceae." Thesis, Griffith University, 2022. http://hdl.handle.net/10072/419713.
Full textThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text
Ngai, Courtney L. "An Investigation of Chemical Identity Thinking." Thesis, University of Massachusetts Boston, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10265119.
Full textChemical identity is a foundational crosscutting concept in chemistry and encompasses the knowledge, reasoning, and practices relevant for the classification and differentiation of substances. Substances are found everywhere – from the chemistry classroom to the kitchen at home – so classification and differentiation of substances is important for everyday decisions as well as challenges that are solved using chemistry. An understanding of chemical identity, then, is essential for scientifically literate citizens in addition to students training to be chemists. A better understanding of how chemical identity thinking develops could be used to inform instruction and education research, with the intent of producing students and citizens who can use their chemical knowledge to reason with in order to practice chemical identity thinking.
This thesis characterizes chemical identity thinking from the perspective of chemical identity knowledge and chemical identity practices, both of which contribute to chemical identity thinking. First, the literature is examined for existing research on how students perceive substances and chemical identity, and a hypothetical learning progression for chemical identity thinking is proposed. This is followed by the design of a qualitative instrument, the CSI Survey, to capture the chemical identity practices exhibited by students at a range of education levels (8th grade – 4th year university). The data collected using the CSI Survey are analyzed using content analysis. Eight unique themes corresponding to chemical identity practices (the application of chemical identity knowledge and reasoning) are revealed by this analysis (change, class, composition and structure, function, organism effect, sensory information, source, tests and experimental values). The application of chemical identity knowledge in biochemical contexts by both expert biochemists and biochemistry students is investigated in the final chapter, and the chemical identity knowledge observed in the biochemical contexts is characterized using the eight themes of chemical identity practices. Suggestions are offered on how the products of the research on chemical identity thinking can be used to inform decisions in both instruction and research.
Burton, Stephanie Gail. "A chemical investigation of Tulbaghia Violacea." Thesis, Rhodes University, 1990. http://hdl.handle.net/10962/d1015725.
Full textHagos, Selam. "Chemical Investigation of Bioactive Marine Extracts." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7301.
Full textGe, Daozhi. "Chemical Investigation of Plant Taxodium ascendens." Thesis, Griffith University, 2018. http://hdl.handle.net/10072/380674.
Full textThesis (Masters)
Master of Science (MSc)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text
Loehn, Clayton William. "Investigation of the monazite chemical dating technique." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/27688.
Full textPh. D.
Park, Young Chul. "Chemical Investigation of Three Antarctic Marine Sponges." Scholar Commons, 2004. https://scholarcommons.usf.edu/etd/1190.
Full textPhatak, Nisarga Laxman. "Chemical investigation of fungicolous and endophytic fungi." Diss., University of Iowa, 2014. https://ir.uiowa.edu/etd/4719.
Full textWang, Qianhe. "Investigation of Acrylated Alkyds." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1366047898.
Full textHuang, Wei Hua. "Chemical investigation on root barks of Oplopanax horridus." Thesis, University of Macau, 2012. http://umaclib3.umac.mo/record=b2590373.
Full textMeng, Xiaoli. "Chemical synthesis and investigation of reactive drug metabolites." Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490798.
Full textSenanayake, Mahima. "A Chemical Investigation of New Zealand Unifloral Honeys." The University of Waikato, 2006. http://hdl.handle.net/10289/2665.
Full textWang, XiuZhu. "Investigation of biological and chemical interactions by AFM." Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615986.
Full textCadorette, Veronica R. "Chemical investigation of Dicranum fulvum for anticancer activity." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/44706.
Full textBiological screening of extracts of various bryophytes showed that the species Dicranum fulvum gave extracts with activity in both in vitro and in vivo bioassays. This plant was thus selected for extraction and fractionation, monitored by iin vitro bioassays.
Isolation was guided by a combination of bioassay and chemical methods, and led to the isolation of three compounds, betulin, 9,l9- cyclolanostâ 23â eneâ 3,25â diol, and B-sitosterol. Purification was achieved by open column, flash column, gel filtration, thin layer chromatography, the chromatotron and crystallization.
The isolated compounds were identified by comparisons of spectroscopic data with those of authentic samples and the matching of experimental and literature melting points and optical rotations.
Master of Science
Phala, Noko Simon. "A theoretical investigation in heterogeneous gold catalysis." Thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/6767.
Full textDespite the nobleness of bulk gold metal in air, small supported gold particles have been shown experimentally to be active in a wide range of chemical reactions. The objective of this work was to study, theoretically, some of the fundamental aspects of the reactivity of gold catalysts. Using activation of CO, CO2 and H2 as a test case, periodic and cluster density functional theory (DFT) calculations, within the generalized-gradient approximation (GGA), were performed to investigate the change in nobility of gold from the extended surface to small clusters. Potential methanol synthesis intermediates were optimized on the Au(111) surface. It was found that the molecules that are stable as gasphase species generally adsorbed weakly on the surface. Surface hydrogenation of CO-derived species appeared to be easier than surface hydrogenation of CO2- derived species. On an AU13 cluster, the energetics of CO2 adsorption and hydrogenation remain unfavourable. The cluster-size dependency of hydrogen and carbon monoxide adsorption was investigated. It was found that small gold clusters (1 to 13 atoms in size) can bind both H and CO strongly. Due to the changes in the orbital spatial symmetries and the energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) with cluster size in this small size range, the adsorption energies depend very strongly on the number of gold atoms present, i.e. each atom makes a difference. For H adsorption, there is a very marked oscillation in adsorption energies, with the clusters with an odd number of gold atoms (with lower LUMO energies) being generally more reactive than the even clusters, up to about 10 atoms when the HOMO-LUMO gap ceases to fluctuate strongly. The role of the support material in activating gold atoms was studied. A hybrid quantum mechanics/molecular mechanics (QMlMM) electronic embedding technique was employed to model the ZnO(000l) surface of zincite. The QM region of the surface, treated by density functional theory, consisted of a total of 13 zinc and oxygen atoms for the zinc-vacant site, and 14 atoms for the bulk-terminated island site. It was found that Au0 and Au+ could be stabilized at the zinc vacant site of this surface. The higher oxidation states are unstable with respect to auto-reduction by the ZnO surface (i.e. their LUMO energies were below the HOMO of a bare ZnO surface. However, gold hydroxyls, where gold has + 1 to +3 oxidation states, can be stabilized at the vacancy. As zinc-substitutional impurities on the bulk-terminated island site, Au+, Au2+ and Au3+ oxidation states can be stabilized. CO was used as a test molecule to probe the chemical reactivity of the gold atoms in different adsorption sites and oxidation states. It was found that supported Au+ was more reactive than Au0, Au2+, or Au3+. Furthermore, CO binds more strongly to supported Au0 than the free Au0 atom. This implies that the support does not simply disperse gold particles, but it also modifies their electronic properties. It was also found that the nucleation of gold atoms to clusters can be affected by the support. Supported charges Au clusters have shorter Au-Au distances than their gas-phase counterparts.
Jacobs, Kelvin Stephen. "Investigation of the activity and selectivity of the MoO3/AI2O3 catalyst and the structural investigation using in-situ raman." Master's thesis, University of Cape Town, 2002. http://hdl.handle.net/11427/5314.
Full textMetathesis is a very versatile reaction, which allows the conversion of Simple, relatively inexpensive olefins into specialty, high-purity olefins which are useful intermediates in the fragrance, agricultural and many other specialty chemical industries. Supported molybdenum on alumina is an active heterogeneous catalyst for the metathesis of olefins. Its activity, as a function of time, passes a maximum. It is known that the activity of molybdenum-based catalyst increases up to monolayer capacity. Catalysts with various Mo-Ioadings were prepared by controlled adsorption method using ammonium heptamolybdate as a precursor. A catalyst using a new slurry impregnation method was also prepared for comparative reasons. Before the metathesis process, the molybdenum catalysts are activated at 550°C under N2 in a fixed bed reactor. The loading of the prepared catalysts was below and above monolayer capacity. It was observed that up to a loading 0.3 g Mo03 per g Ab03 the initial conversion increases more than proportional to the Mo03- loading. The catalysts with a Mo03-loading higher than 0.3 g Mo03 per gram AIz03 show initially a lower activity, ie. The activity per molybdenum atom in the catalyst decreases. With increasing time-on-stream the activity of the catalysts declines. The decline is much stronger over the catalysts with a rligher initial activity.
Ostler, Richard Bruce. "An investigation of intracellular PDT mechanisms." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301122.
Full textSegraves, Nathaniel Lee. "Chemical investigation of biologically active alkaloids from marine sponges /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2005. http://uclibs.org/PID/11984.
Full textGlowacki, David Ryan. "Investigation of Atmospheric Chemical Mechanisms Using Experiments and Theory." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485587.
Full textIngham, Angela M. "Models in chemical education : an investigation into their uses." Thesis, University of Surrey, 1988. http://epubs.surrey.ac.uk/771366/.
Full textLebar, Matthew D. "Antarctic Tunicates and Endophytic Fungi: Chemical Investigation and Synthesis." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3638.
Full textPowell, Mark William. "An investigation of chemical factors influencing bitumen-mineral adhesion." Thesis, University of Hertfordshire, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314732.
Full textRao, Vikram Mohan. "Investigation of Decision Processes in Chemical Substitution Decision Making." Thesis, The George Washington University, 2021. http://pqdtopen.proquest.com/#viewpdf?dispub=28261055.
Full textPatel, Vinodkumar H. "Chemical kinetic investigation of a commercial batch reactor process." Thesis, Aston University, 1987. http://publications.aston.ac.uk/10185/.
Full textOkpoko, Egwono Kelvin. "Chemical-looping combustion : investigation of Cu-based oxygen carriers." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/11749.
Full textHong, Baoyu. "Investigation on chemical steps of thymidylate synthase catalyzed reaction." Diss., University of Iowa, 2007. http://ir.uiowa.edu/etd/125.
Full textVon, Stein Ferdinand. "A chemical investigation of Dendrobium discolor and Senecio madagascariensis." Thesis, Queensland University of Technology, 2002.
Find full textMoore, Peter Nathaniel 1974. "A fundamental investigation of surface-induced skin irritation." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8532.
Full textIncludes bibliographical references.
Surfactants frequently come in contact with the skin in the form of personal care products, where they are used to improve the wetting and oil solubilizing qualities of the products. Surfactants are also known to induce skin irritation by damaging the barrier properties of the stratum corneum, the outer layer of the skin, and denaturing proteins in the epidermis and the dermis. The goal of this thesis has been to understand the relationship between the physicochemical properties of surfactant solutions and their skin irritation potential. In vitro tests were developed to measure: (1) the effect of surfactants on the barrier properties of the skin, (2) the concentration of surfactant in the skin, and (3) surfactant-induced protein denaturation, all of which can be related to skin irritation. The physicochemical properties of the surfactant solution, specifically, the concentration of the surfactant monomers (unmicellized surfactant), the composition of the surfactant monomers, and the size and shape of the surfactant micelles, were related to the results of these tests. An in vitro skin irritation test was developed that measures the electrical conductivity of pig skin to quantify the reduction in the barrier properties of the skin, or the skin damage, induced by surfactant solutions. Skin conductivity was found to be directly related to the transdermal water permeability, directly relating the skin conductivity to in vitro skin irritation. Skin conductivity was used to measure the in vitro skin irritation potential of mixtures of the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant dodecyl hexa(ethylene oxide) (C12E6), and a relationship was observed between the surfactant monomer concentration and
(cont.) the skin conductivity. The in vitro skin irritation test correctly ranked the in vivo irritation potential of three mild commercial soap bars-Dove, Lever 200, and Ivory. In order to understand the relationship between the micelle concentration and the surfactant-induced damage to the skin, a method was developed to measure the penetration of 14C-radiolabeled SDS surfactant into pig skin. It was found that both monomeric and micellar SDS are able to penetrate into the skin, and that the contribution of the micellar SDS to the concentration of SDS in the skin is comparable to the contribution of the monomeric SDS. SDS penetration into the skin was also measured in the presence of poly(ethylene oxide) (PEO), which forms PEO-bound SDS micelles, and C12E6, which forms SDS/C12E6 mixed micelles. In mixtures of PEO-bound and free SDS micelles, the PEO-bound SDS micelles were found not to penetrate into the skin while the free SDS micelles were found to penetrate. Mixing SDS with C12E6 led to a reduction in the penetration of SDS into the skin by reducing the SDS monomer concentration, as well as by reducing, or preventing altogether, the penetration of micellar SDS. The hydrodynamic radii of the free SDS micelles (21 A), the PEO-bound SDS micelles (25 A), and the SDS-C12E6 mixed micelles (24-30 A) were measured using dynamic light scattering. Based on these results, a new model of surfactant penetration into the skin was proposed, in which the penetration of micellar surfactant into the skin is limited by the size of the micelles...
by Peter Nathaniel Moore.
Ph.D.
Harding, Jonathon R. (Jonathon Robert). "Investigation of oxidation in nonaqueous lithium-air batteries." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98707.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 161-177).
The demand for clean energy in portable applications is driving the development of high specific energy batteries, which will enable automobiles powered by electricity derived from renewable energy sources such as solar and wind. Lithium-air batteries are a promising avenue for advancing the energy storage capabilities beyond that of current lithium-ion technology. These batteries face a number of challenges which prevent their practical implementation in devices. This thesis explores possible mitigations for two of these challenges: (1) the high charging overpotential and (2) the volatility and poor oxygen conduction of liquid electrolytes in Li-air batteries. In the first part, Vulcan carbon-based electrodes were developed where chemically-synthesized lithium peroxide was included during the electrode preparation process. Variants of these electrodes which further included noble metal catalyst nanoparticles (Au, Pt, and Ru) were also prepared, and Pt and Ru were both demonstrated to begin oxidizing Li₂O₂ 500 mV lower than required for carbon-only or Au-containing electrodes. Using a differential electrochemical mass spectrometer (DEMS) designed and built over the course of this thesis, we showed that Ru-containing electrodes produce oxygen throughout the oxidation of Li₂O₂, while Pt generated both carbon dioxide and oxygen, indicative of electrolyte decomposition. These results served as a foundation for future efforts to develop solid catalysts for the oxidation of Li₂O₂ in Li-air batteries. In the second part, Li-O₂ devices using a solid electrolyte based on poly(ethylene oxide) (PEO) were developed. The discharge performance at room temperature and 60 °C was characterized, with dramatically higher discharge capacity and rate capability achievable at the elevated temperature. DEMS was used to show that the gases evolved during charging in argon were sensitive to the temperature of charging, with additional carbon dioxide observed at and above 50 °C. Finally, the autoxidation of PEO at 60 °C in Li-O₂ environments was studied, where NMR and DEMS measurements showed that the rate of PEO autoxidation increases with increasing applied potential, and that this reaction has a significant impact after only one charging cycle, identifying another condition that must be met for stable and practical Li-air batteries.
by Jonathon R. Harding.
Ph. D.
Chung, Elena Yin-Yin. "Investigation of Chemical Looping Oxygen Carriers and Processes for Hydrocarbon Oxidation and Selective Alkane Oxidation to Chemicals." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469182957.
Full textElliot, Mark. "An investigation of propellant stabiliser degradation products." Thesis, University of the West of Scotland, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259888.
Full textSimmons, B. "A shock tube investigation in soot formation." Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371060.
Full textMoes, Sebastian. "Investigation into Potential Mosquitocides for Future Development." Thesis, Umeå universitet, Kemiska institutionen, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-150542.
Full textTamuli, Roktima. "Chemical Investigation of Clerodendrum polycephalum for Anti-Malarial Compounds and its Chemical Diversity with Australian Clerodendrum." Thesis, Griffith University, 2022. http://hdl.handle.net/10072/414921.
Full textThesis (Masters)
Master of Science (MSc)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text
Razi, Javeed. "Investigation of the structure of coal using ultrasonic energy." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28519.
Full textEach of the extracts were analyzed in the following ways: (a) Ultimate analysis; (b) Molecular weight determination; (c) FT-IR spectra; (d) Differential scanning calorimetry; and (e) Thermogravimetric analysis.
In the extraction process the first extraction was simple Soxhlet extraction. The residue from this was irradiated with ultrasonic energy and then re-extracted. The residue of the second extraction was ground to a small size and re-extracted without using ultrasonics. The fourth extraction was on the residue of the third extract, using ultrasonics.
In general the molecular weight of each successive extract increased while the amount of extract decreased. From the chemical analysis and the molecular weights it appears that the successive extracts are, by and large, members of a family of addition polymers. This finding, coupled with the fact that over 60% of the total coal could be extracted by the procedures used, shows that the bulk of this coal does not consist of a cross-linked polymer.
As was shown in previous research the rate of extraction using ultrasonic energy did not rupture and chemical bonds and the extraction rate curve approximated that predicted by Fick's Law, being slightly lower initially and slightly higher later. This work confirmed this. It can be concluded that the only effect of the ultrasonic irradiation was to speed up the relaxation of the glassy coal matrix and release the small molecules so that they could diffuse.
The diffusivities of the molecules being extracted was determined for different sized particles. The apparent diffusivity became smaller as the particle size became smaller. This is the opposite of what would be expected if the molecules were diffusing out of small pores.
To explain this anomalous effect it has been hypothesized that many of the coal molecules are trapped inside a molecular cage or clathrate, which has been formed from fossilized lignin of the original plants.
Some auxiliary experiments were carried out to ascertain the practicability of shattering the coal by soaking the coal particles in a liquid at high pressure and temperature and then suddenly releasing the pressure to let the liquid flash to vapor. The process worked well to produce small coal particles, but there were difficulties in recovering all the coal particles when pyridine was used as the liquid.
Mao, Kangyi. "Microstructural investigation of tablet compaction and tablet pharmacological properties." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62108.
Full textCataloged from PDF version of thesis.
Includes bibliographical references.
In current tablet manufacturing processes, there is a knowledge gap concerning material transformation and the subsequent impact on tablet properties; this gap presents a barrier to rational formulation / process design. In this study, it was hypothesized that the understanding of tablet microstructure is pivotal in bridging our knowledge about the materials, the manufacturing process, and the tablet properties. A series of X-ray micro computed tomography (microCT) characterization methods were developed to untangle material interactions during tablet manufacturing process, leading to an interpretation of tablet compaction mechanisms through 3-D representation of microstructural features. Numerical simulation of liquid intrusion based on microCT data was utilized in calculating tablet microstructure permeability, introducing a novel parameter for characterization of tablet dissolution properties. A tablet holder was designed and used in combination with paddle dissolution test to investigate tablet dissolution process, enabling the classification of dissolution mechanisms and identification of correspondent formulation design strategies. When incorporated with permeability results, a quantitative dissolution model capable of separating the contributions from disintegration and surface dissolution was derived. The dissection of the dissolution process provides a scientific framework supporting the Quality by Design paradigm for product and process development. . This work provides a strategy for building an integrated formulation design and characterization system incorporating microstructural analysis. It opens up an approach in which microstructure becomes a critical target for design and optimization.
by Kangyi Mao.
Ph.D.
Beckham, Gregg Tyler. "A computational investigation of nucleation processes in organic crystals." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42433.
Full textIncludes bibliographical references.
Nucleation processes are ubiquitous in nature and technology. For instance, cloud formation in the atmosphere, the casting of metals, protein crystallization, biomineralization, the production of porous materials, and separation of pharmaceutical compounds from solution are a few examples of relevant nucleation processes. One pathway for nucleation to occur is homogeneous nucleation, in which an embryo of a more stable phase forms within an original metastable medium. Homogeneous nucleation is an activated process, meaning that a free energy barrier must be overcome for the transition to take place, and the height of the free energy barrier determines the rate at which the process will occur. Despite considerable advances in both theoretical and experimental techniques to date, determining nucleation mechanisms for real systems remains a considerable technical challenge. The aim of this thesis is therefore to apply molecular simulation techniques to elucidate nucleation mechanisms in organic crystals. Specifically, the newly developed methods of aimless shooting and likelihood maximization are applied for the first time to study nucleation processes in complex and technically relevant systems. The first portion of the thesis examines polymorphism, or the ability of a material to pack in different crystal lattices whilst retaining the same chemical composition. Transformation to a more stable polymorph can readily occur in the solid state, which has broad implications in pharmaceutical processing. To date, over 160 mechanisms have been proposed for polymorph transitions in the solid state, but none have been definitively verified. A model compound, terephthalic acid, is chosen for computational studies because it is similar in size to a small molecule therapeutic and exhibits a common bonding motif for organic crystals. Using aimless shooting and likelihood maximization, the mechanism of the solid state polymorph transformation in terephthalic acid is shown to be comer nucleation. The mechanism shows that for a given nucleus size, the interfacial area between the crystalline domains is minimized, thus reducing the unfavorable surface free energy penalty required for nucleation to occur.
(cont.) Furthermore, based on the results presented, it is anticipated that corner nucleation may be a common mechanism for many polymorph transformations in hydrogen bonded crystalline materials. The second portion of the thesis investigates the mechanism of freezing a subcooled liquid to form a crystal. This phenomenon has widespread application across many technical domains. Similar studies to date on freezing have been limited to model systems, such as Lennard-Jones particles or hard spheres. Benzene is chosen as a model compound. A periodic system is constructed and aimless shooting and likelihood maximization are applied to determine the nature of the critical nucleus. Local order analysis is implemented to distinguish among solid and liquid-like molecules. Preliminary results indicate that the critical nucleus is on the order of 200-300 molecules at 50 K subcooling. This thesis demonstrates that the complementary molecular simulation techniques of aimless shooting and likelihood maximization offer fundamental insight into nucleation mechanisms in molecular crystals. Knowledge of the mechanism from likelihood maximization is essential for accurate free energies and pathway optimization methods, and it should therefore be applied in computational studies of rare events prior to free energy or rate constant calculations. Moreover, these methods provide quantitative understanding of the important physical variables that determine experimentally observable rates and can further aid in experimental design.
by Gregg Tyler Beckham.
Ph.D.
Von, Holt Sean Thomas. "An investigation into column flotation of South African coals." Master's thesis, University of Cape Town, 1992. http://hdl.handle.net/11427/21992.
Full textThe high efficiency of separation of fine (typically the -150 μm fraction) particles achievable with column flotation technology is well established. The principal aim of this thesis is to investigate whether column flotation can be used to recover saleable, particularly low-ash quality, coal from South African coal fines which are presently discarded. Samples of thickener underflow fines from the Durnacol, Kleinkopje and Greenside Collieries were used in laboratory column testwork. In addition, on-line column trials were performed at the Kleinkopje Colliery. The effects of co 1 umn operating parameters were established using both one-variable-at-a-time testing and fractional factorial design experiments. An investigation into coal slurry conditioning using oil and oil-water dispersions was also undertaken. The results of laboratory and plant column testwork showed that it was possible to recover the desired quality products from all three of the coal fines samples investigated. For all the coals tested, better grades were obtained at any given yield from column cell flotation than with conventional (batch) froth flotation. The test results also demonstrated that the column cell is best suited to recovering and upgrading the finer (< 75 μm) size fractions. Column performance was found to be strongly affected by the petrographic composition of the coal fines feed, i.e. by coal TYPE. Coals with high vitrinite and, conversely, low inertinite contents were found to be the most easily floatable. Depending on the coal TYPE, the rate of mass transport in either the pulp or froth phase was found to be rate limiting; this in turn dictated which operating parameters affected product yields and grades. Existing methods of conditioning coal slurries were found to be inadequate. Considerable scope for improvement in coal conditioning lies in better choice of collector and "promotor" reagents as well as in designing more energetically efficient conditioning vessels.
Abdallah, Suaad Audat. "Investigation of Oxidative DNA Damage from Ionizing Radiation." University of Toledo Health Science Campus / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=mco1349377002.
Full textEndres, Derek. "Numerical Investigation of pulsed chemical vapor deposition of aluminum nitride." Connect to resource, 2010. http://hdl.handle.net/1811/44821.
Full textMcOwen, Dennis Wayne. "Investigation of solid fuel conversion in the chemical looping process." Connect to resource, 2010. http://hdl.handle.net/1811/45381.
Full textChaulk, Steven George. "New chemical approaches for the investigation of RNA structural dynamics." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ63597.pdf.
Full textNave, Andy [Verfasser]. "Physico-chemical investigation of plasma induced deposition processes / Andy Nave." Greifswald : Universitätsbibliothek Greifswald, 2017. http://d-nb.info/1141405997/34.
Full textMitchell, James. "An investigation of the physico-chemical properties of clay suspensions." Thesis, Keele University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.647445.
Full textPhipps, Mark. "A physico-chemical and microcalorimetric investigation of an antibacterial drug." Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262353.
Full textDENG, LEI. "Investigation of Electric Arc Furnace Chemical Reactions and stirring effect." Thesis, KTH, Materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109248.
Full textHance, Glen W. "The chemical and electrochemical investigation of the glassy carbon surface /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487324944215524.
Full textYeh, Thomas M. "Syngas chemical looping particle production scale up and kinetics investigation /." Connect to resource, 2009. http://hdl.handle.net/1811/36976.
Full textLi, Hang, and n/a. "Chemical investigations of Natural Products from Australian Marine Sponge-Derived Fungi." Griffith University. Eskitis Institute for Cell and Molecular Therapies, 2007. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20081103.091038.
Full textLi, Hang. "Chemical investigations of Natural Products from Australian Marine Sponge-Derived Fungi." Thesis, Griffith University, 2007. http://hdl.handle.net/10072/367548.
Full textThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Eskitis Institute for Cell and Molecular Therapies
Full Text