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Study of chondroitin sulphate abc lyases and their use in combination for promotion of neurite growthTam, Kin-wai., 譚健偉. January 2010 (has links)
published_or_final_version / Physiology / Doctoral / Doctor of Philosophy
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Calcium sulphate deposition on heated metal surfacesPalethorpe, S. J. January 1986 (has links)
The accumulation of undesired matter at heat transfer surfaces (fouling) is a severe problem to industry. The growth of calcium sulphate dihydrate on heated metal surfaces has been examined and a mechanism for the effect of surface roughness on the amount of deposition has been proposed. A novel piece of equipment was designed and constructed in which the growth of crystals on heat transfer surfaces with different surface roughnesses could be observed under controlled solution conditions. The test section was a transparent rectangular channel into Rhich three 25 mm diameter test pieces could be inserted such that the polished faces were planar with the rear face of the channel. The back faces of these test pieces were heated by contact with hot Mater. Using Reynolds numbers of 300 to 13,500 and calcium sulphate 2+ solutions with bulk concentrations from 20 to 50 mH Ca , no gross effect due to surface roughness was seen. However a limited effect, which distinguished grit-blasted surfaces from polished surfaces, was 2+ found in experiments with a bulk concentration from 28 to 33 mH Ca . In all of the experiments it was observed that the presence of bubbles enhanced crystal growth. It was also found that the amount of deposition formed on any surface decreased with decreasing dissolved oxygen content of the bulk solution. It is suggested that a bulk concentration of approximately 33 mH 2+ Ca is a critical level of supersaturation, which corresponds with the so-called metastable limit of supersaturation. The surface roughness effect may be associated with two factors. Firstly, as the critical supersaturation is approached crystal growth is enhanced at certain sites. in particular the edges of bubbles. Secondly, very rough surfaces. such as grit-blasted surfaces. more readily support and initiate bubble formation and consequently the grit-blasted surface shows greater growth. Additional work with a different test rig. using a stagnant solution, indicated that suppression of bubble formation during an experiment, either by initially degassing the surface or by pressurising the system, decreased the amount of crystal growth. This work suggests that a surface roughness effect exists which is related to the presence of bubbles at the surface. Consequently the amount of deposition can be decreased either by controlling the formation of the bubbles (e.g. by completely degassing both the solution and the surface. and pressurising the system). or by polishing the surface. However. the surface roughness effect was most apparent between the very coarse, grit-blasted surfaces (R ~ 2.90 um) and the a medium finish 180 or 240 Grit surfaces (R ~ 0.23 um). a Little or no further improvement was obtained in polishing to a mirror finish. i. e. 0.25 or 0.1 um (R ~ 0.03 um). a further polishing beyond removing gross roughness would not appear to Therefore. for industrial purposes, yield sufficient benefit to justify the large cost involved. It is recommended that further work be undertaken to determine whether the deposition which occurs in the absence of bubbles is influenced by the surface roughness, and whether other chemical system and surfaces behave similar to the calcium sulphate - stainless steel system studied in this work. Moreover, additional work should be undertaken to examine the effect of surface physical properties on crystal and bubble nucleation and growth.
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NEW PHASES IN THE HYDROUS FERRIC SULFATE SYSTEM, A SUPPORTING ARGUMENT THAT THE MINERAL LAUSENITE IS OF FORMULA FE2(SO4)3∙5H2O AND THE CRYSTAL STRUCTURE REFINEMENT AND HYDROGEN BONDING SCHEME OF THE MINERALS QUENSTEDTITE AND ROMERITEWestland, ROBIN 04 September 2012 (has links)
A series of experiments were conducted to explore the hydration state of the mineral lausenite. The experiments of Posnjak and Merwin (1922) were recreated and the conclusion is reached that lausenite is of mineral formula Fe2(SO4)3∙5H2O, rather than Fe2(SO4)3∙6H2O as suggested by Posnjak and Merwin (1922). This conclusion is based on the X-ray diffraction data which found that the Posnjak and Merwin experiments produced a phase whose pattern matched that of the pentahydrate identified by Majzlan (2005). The refractive index data and morphology of this phase is also a match for the mineral described previously as a hexahydrate by Posnjak and Merwin (1922) and Lausen (1928).
Synchrotron X-ray diffraction data was collected from a possible new phase in the hydrous ferric sulfate system. The data were analyzed and a unit cell was identified with monoclinic unit cell dimensions of a = 7.532(3)Å b = 12.551(6)Å c = 7.077(4)Å and β = 96.775(8)° with a unit cell volume of 664.4Å3. This phase was determined to grow only at temperatures above 85°C and at a RH of ~23%.
The atomic structures of the minerals quenstedtite [Fe2(SO4)3∙11H2O] and romerite [Fe2+Fe3+2(SO4)4∙14H2O] are refined, hydrogen positions are identified and hydrogen bonding scheme is discussed. The weakest hydrogen bonds are found to occur between layers of differently coordinated tetrahedral groups in both romerite and quenstedtite. The transition from romerite to quenstedtite involves the oxidation of the ferrous iron in romerite converting into a Fe3+(SO4)∙5H2O cluster. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2012-09-02 10:11:21.232
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Geochemical characterization of coastal precipitation: Natural versus anthropogenic sources.Wadleigh, Moire Anne. Kramer, J. R. Schwarcz, H. P. Unknown Date (has links)
Thesis (Ph. D.)--McMaster University (Canada), 1989. / Source: Dissertation Abstracts International, Volume: 62-13, Section: A, page: 0000.
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Chemical and physical properties of acid mine drainage flocBohan, Catherine M. January 1900 (has links)
Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains ix, 63 p. : ill. Includes abstract. Includes bibliographical references (p. 57-63).
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PAPS synthetase : structure-function studies of the bifunctional enzyme /Singh, Bhawani. January 2002 (has links)
Thesis (Ph. D.)--University of Chicago, Department of Chemistry, December 2002. / Includes bibliographical references. Also available on the Internet.
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Assimilatory sulfur metabolism in marine microorganisms /Cuhel, Russell Lee. January 1980 (has links)
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Biology, 1981. / Supervised by Holger W. Jannasch. Vita. Includes bibliographical references (leaves 359-373).
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The role of sulfur in salt marsh metabolism.Howarth, Robert Warren. January 1979 (has links)
Thesis (Ph. D.)--M.I.T., Dept. of Biology, 1979. / Supervised by John M. Teal. Vita. Includes bibliographies.
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Otimizacao do processo de obtencao de zirconia via precipitacao do sulfato basico de zirconioRICCI, DOLORES R. 09 October 2014 (has links)
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01779.pdf: 1867284 bytes, checksum: 561bc30f019f8009c1ab308bcee6e3ca (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Removal and recovery of aluminium and sulphate ions from an alkaline medium using solvent extractionMpinga, Cleophace Ngoie January 2009 (has links)
Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: Chemical Engineering
in the Faculty of Engineering
at the Cape Peninsula University of Technology / Throughout the world, many water resources are polluted by industrial and domestic
effluents, acid mine drainage, etc. The increasing awareness and concern about the
environment has motivated in the recent years extensive research into developing new
efficient, cost effective and environmentally sound technologies to treat industrial solutions
bearing metals and sludges. From the literature review, much research has been, and is still being devoted to the
performance of solvent extraction (SX) of aluminium or sulphate in acidic solutions and how
to improve such performance. There is a general lack of information on liquid-liquid
extraction of aluminium or sulphate in an alkaline solution. Thus, the need for a systematic
investigation into the solvent extraction of aluminium and sulphate in an alkaline medium was
important. This thesis focuses on the study of solvent extraction of aluminium and sulphate
from alkaline solutions using Trioctylmethylammonium chloride, (Aliquat 336), in Kerosene as
diluent.
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