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Respirable quartz in coal mines in the Mpumalanga region of South Africa over the period 2002 to 2006Doyle, Bruce Anthony 16 April 2010 (has links)
MPH, Occupational Hygiene, School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, 2009 / Introduction:
By 2030 silicosis should be eliminated in South Africa. This statement was made by
the Labour Minister, Mr. Membathisi Mdladlana on 28 June 2004 during the launch of
the National Programme for the Elimination of Silicosis in Johannesburg. Following
this launch the mining industry set its own milestone, which is to eradicate this disease
by 2014. Historically research has generally focused on the health effects associated
with exposures to coal dust, whilst limited work has been done on personal exposures
to respirable crystalline silica (commonly known as quartz), which is the main cause of
silicosis in the mining industry. Given the number of people that are involved in coal
mining, together with the seriousness of diseases associated with respirable quartz
exposure, such as silicosis and tuberculosis, it is important to quantify these
exposures. The aim of this study was to ascertain the magnitude of employee
exposures to respirable quartz, in the Mpumalanga region of the South African coal
mining industry, over the period 2002 and 2006.
Objectives:
The objectives of this study are:
• To describe respirable quartz concentrations in 41 coal mines in the
Mpumalanga region of South Africa over the period 2002 to 2006;
• To compare respirable quartz concentrations in nine magisterial districts of the
Mpumalanga region of South Africa over the period 2002 to 2006, to the South
African Occupational exposure limit of 0.1 mg/m3 and the American Congress
of Governmental Industrial Hygienists (ACGIH) Threshold Limit value of
0.025 mg/m3;
• To describe twenty four activity areas in 41 coal mines in the Mpumalanga
region of South Africa, over the period 2002 to 2006, which exceed 50 % of the
South African Occupational exposure limit of 0.1 mg/m3 (generally referred to
as the action limit).
3
Methodology:
The study setting comprises the workings of coal mines within the Mpumalanga
region, where various types of occupations exist. The research conducted consisted
of a descriptive study of retrospective respirable Time Weighted Average quartz
concentration results obtained from mines that use the company Colliery
Environmental Control Services (CECS) as their occupational hygiene service
provider. CECS provided the data that was analysed for this research. Sample
collection and analysis for respirable quartz was done using widely accepted
International methodologies.
Results:
The overall median respirable quartz concentration for all mines were 0.007 mg/m3,
whilst the mean was 0.038 mg/m3. The highest respirable quartz concentration
measured was 2.197 mg/m3 and the lowest 0.000 mg/m3. The majority of the mines,
i.e. 30, are situated in the Kriel, Secunda and Witbank magisterial districts, these
districts account for 78 % of the total number of measurements taken. A total of 191
measurements (8 %) and 674 (29 %) exceeded the South African OEL of 0.1 mg/m3
and ACGIH TLV of 0.025 mg/m3 respectively with the Secunda district having the
most measurements that exceeded both sets of limits (58 and 205 respectively). The
majority of measurements, i.e. 1784 (76 %), were from six activity areas and four
hundred and ninety one (21 %) of the total measurements taken were from the
continuous miner activity area. The highest ranked activity area is the longwall mining
one, which has a median respirable quartz concentration of 0.044 mg/m3. The highest
respirable quartz concentration, 2.197 mg/m3, was measured in the roving plant
activity area, which was followed by measurements of 1.706 mg/m3 and 1.528 mg/m3
in the continuous miner and unknown activity areas respectively. The longwall mining
activity area recorded the most measurements that exceeded the 50 % action limit
and 0.1 mg/m3 OEL, these been 47 and 38 respectively.
4
Discussion and Conclusion:
This research report describes similar exposure findings as has been reported
internationally. Persons employed in the high risk activity areas on the 41 mines
studied over the period 2002 to 2006 in the Mpumalanga region are at risk of
developing quartz-associated diseases, such as silicosis.
Recommendations:
It is recommended that the effectiveness of implemented interventions need to be
investigated and appropriate intervention strategies be implemented. Airborne quartz
contents from the nine magisterial districts and 24 activity areas should be analysed
and individual samples taken from the high risk tasks should be individually analysed
for their percentage airborne quartz content.
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Fabrication of micro and nano channel systems in quartz substrates by laser micro-machining. / CUHK electronic theses & dissertations collection / Digital dissertation consortiumJanuary 2002 (has links)
Qin Shuijie. / "August 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 109-123). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.
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Mise en oeuvre des surfaces spécifiques en vue de la détection de bactéries pathogènes par diffusion RamanKengne-Momo, Rosine Pélagie 06 May 2011 (has links) (PDF)
L'objectif de cette thèse est de synthétiser de nouvelles surfaces spécifiques nécessaires à l'immobilisation des biomolécules ; visant à développer à terme un biocapteur pour la détection de pathogènes en industrie agroalimentaire. Cette nouvelle procédure de fonctionnalisation de surface consiste d'une part à greffer des molécules organiques sur un substrat métallique à partir d'une réaction électrochimique et d'autre part de synthétiser un monomère photopolymérisable sur tout type de surface. Ces surfaces sont enfin utilisées pour immobiliser les biomolécules. Ce procédé ainsi développé permet d'éliminer les multiples étapes, l'utilisation excessive de réactifs observés dans les protocoles classiques de fonctionnalisation de surface pour la capture de microorganismes. Deux stratégies de fonctionnalisation ont été investiguées : la polymérisation sur une plaque de platine et le dépôt de monocouche sur une surface d'or. La fonctionnalisation de surfaces ainsi que l'immobilisation de biomolécules ont été caractérisées par la spectroscopie Raman, la microbalance à cristal de quartz, la microscopie à force atomique (AFM) pour le premier et en plus la microscopie à fluorescence pour le second. Les résultats de la fonctionnalisation de surfaces par dépôt de polymère ont montré, une déstabilisation du polymère en présence de l'eau. Afin d'optimiser la synthèse, nous avons travaillé en milieu inerte, sous alumine activée. De plus, on note une large couverture de la zone spectrale des biomolécules par les signaux du polymère ; Pour le dépôt de monocouche, l'on a obtenu une surface très réactive, homogène. La diffusion Raman est la principale technique de caractérisation utilisée. Elle présente l'avantage d'être une méthode de caractérisation physico-chimique non destructive et non invasive. Longtemps délaissée dans les sciences du vivant, cette méthode apparaît maintenant particulièrement prometteuse grâce à un développement récent de spectromètres intégrés performants. La diffusion Raman sur la monocouche déposée montre une intensité accrue des signaux par l'utilisation de la surface d'or et un spectre plus dégagé conduisant à l'identification aisée des biomolécules après fixation. Elle permet non seulement d'identifier les bandes de vibrations de chaque groupement mais aussi la conformation des structures. Les résultats d'immobilisation ont montré que l'accroche des biomolécules sur les surfaces fonctionnalisées était spécifique. La fonctionnalisation de surface d'or par dépôt de monocouche constitue finalement une technique très rapide à mettre en œuvre, peu coûteuse permettant d'ancrer efficacement les biomolécules et peut être utilisée pour diverses applications. La synthèse du monomère photopolymérisable a été abordée et est en cours d'investigation.
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Deep chemical etching on quartz substrates and integrated passive devicesHuang, Chuan-Yi 29 July 2010 (has links)
The purpose of the thesis is to investigate and the corrosion resistance of the masking materials on quartz substrates in deep chemical etching using NH4HF2 solutions. Masking materials, including Cr/Au, PLA-900 position photoresist, and NPR-2500F negative photoresist were used for test. In the deep etching of the quartz substrates, we observed changes of adhesion of the masking materials. The process parameters obtained from deep etching were used to fabricate quartz resonators. Before etch, the etch masks using Cr/Au thin films were deposited on both sides of the quartz substrates. Cr/Au masking materials were stripped after the etching, and Cr/Au electrodes were deposited by sputtering on both sides of quartz substrates. Finally, the quartz resonators were obtained by dicing. Passive devices, including capacitors and inductors were also fabricated and measured for integrated passive devices, such as band-pass filters.
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The study of temperature oefficient of SAW frequency for AlN thin films on LiNbO3 and ST-quartzLee, Yi-Hung 12 July 2002 (has links)
In this study, we use the reactive rf magnetron sputtering method with deposition parameters of RF power of 370W, sputtering pressure of 15 mTorr, substrate temperature of 400¢J, nitrogen concentration (N2/N2+Ar) of 30% and 40%, to deposit highly c-axis orientation AlN thin films on Z-cut LiNbO3 and ST-cut quartz piezoelectric substrate, respectively.
The material characteristics of AlN films deposited on Z-cut LiNbO3 and ST-cut quartz substrate with different thickness were obtained by means of the analyses of XRD, SEM and AFM. Besides, the interdigital transducers (IDTs) were fabricated on the bi-layers structure. The AlN film thickness of piezoelectric bi-layers structure was varied in order to discuss its effect on SAW devices and the temperature coefficient of frequency (TCF) of AlN. From the experimental results, it reveals that the center frequency and TCF of SAW filters increase with the increased AlN thin film thickness. Besides it can be concluded that poly-crystalline AlN exhibits a positive temperature coefficient of frequency (TCF).
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Crack healing as a function of pOH- and fracture morphologyFallon, Jessica Anne 17 February 2005 (has links)
Crack healing in quartz has been investigated by optical microscopy and interferometry
of rhombohedral ( 1 1 10 ) cracks in polished Brazilian quartz prisms that were annealed
hydrothermally at temperatures of 250°C and 400°C for 2.4 to 240 hours, fluid pressure
Pf = Pc = 41 MPa, and varying pOH- (from 5.4 to 1.2 at 250°C for fluids consisting of
distilled water and NaOH solutions with molalities up to 1). Crack morphologies before
and after annealing were recorded for each sample in plane light digital images. Crack
apertures were determined from interference fringes recorded using transmitted
monochromatic light (l = 598 nm). As documented in previous studies, crack healing is
driven by reductions in surface energy and healing rates are governed by diffusional
transport; sharply defined crack tips become blunted and split into fluid- filled tubes and
inclusions. A rich variety of fluid inclusion geometries are also observed with nonequilibrium
shapes that depend on initial surface roughness.
Crack healing is significant at T=400°C. Crack healing is also observed at T=250°C for
smooth cracks with apertures <0.6 mm or cracks subject to low pOH-. The extent of
crack healing is sensitive to crack aperture and to hackles formed by fine-scale crack
branching during earlier crack growth. Crack apertures appear to be controlled by
hackles and debris, which prop the crack surfaces open. Upon annealing, crack
apertures are reduced, and these reduced crack apertures govern the kinetics of
diffusional crack healing that follows. Hackles are sites of either enhanced or reduced
loss of fluid-solid interface, depending on slight mismatches and sense of twist on
opposing crack surfaces. Hackles are replaced either by healed curvilinear quartz
bridges and river patterns surrounded by open fluid-filled crack, or by fluid- filled tubes
surrounded by regions of healed quartz. For a given temperature, aperture and anneal
time, crack healing is enhanced at low pOH- ( £ 1.2) either because of changes in the
hydroxylated quartz- fluid interface that enhance reaction rates or because of increased
rates of diffusional net transport of silica at high silica concentrations.
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Study of nanoimprint process by quartz glass moldFan, Chen-Yi 15 August 2008 (has links)
This study investigates sub 200nm half-pitch polymer structures by nanoimprint process. The trench structures were fabricated on quartz glass with various depths and widths by FIB. To investigate the best nanoimprint process on SU-8, we studied various parameters such as: imprinting temperature, imprinting pressure, and temperature for de-molding, etc. ¡@This study had successfully defined 50nm width with different depths on to SU-8 by imprint. ¡@Imprint temperature above Tg 30¢J with constant pressure on continuous impressing and de-mold in room temperature would result in better imprinting results. The filling rate of this nanoimprint technology was measured by atomic force microscopy. ¡@For structures above/near 100nm half-pitch, the filling rate is nearly 100%.
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Analysis of lithic artefact microdebitage for chronological determination of archaeological sites /Susino, George J. January 2007 (has links)
Texte remanié de: Thesis--University of Wollongong. / Bibliogr. p. 132-139.
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Cathodoluminescent quartz textures and fluid inclusions in veins of the porphyry copper-molybdenum deposit in Butte, Montana : constraints on physical and chemical evolution of the hydrothermal system /Rusk, Brian Geoffrey, January 2003 (has links)
Thesis (Ph. D.)--University of Oregon, 2003. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 211-235). Also available for download via the World Wide Web; free to University of Oregon users.
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Synthesis and characterization of molecularly imprinted polymers and their application in preconcentrators for gas phase sensorsFu, Yi, January 1900 (has links)
Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xi, 204 p. : ill. (some col.) Includes abstract. Includes bibliographical references.
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