Matched weight polyvinyl chloride (PVC) filters are currently available for use in total dust air sampling. This paper studies the utility of employing two superimposed filters in a cassette. Cassettes containing "paired" PVC filters were employed, in the same way matched weight filters would be used, during side by side sampling studies with cassettes housing single PVC filters, to determine whether the presence of two filters in a cassette presented problems during sampling. The effects of dust type, particle breakthrough, moisture concentration, and increased pressure drop from the addition of a second filter were studied. The presence of static electricity between filter pairs was also noted. Under recommended loading conditions "paired" filters seemed to perform as well as single filters in all aspects studied. Due to large filter weight variations found within individual batches of PVC filters, randomly selected filter pairs should not be used as actual matched weight filters.

No description available.

Thesis (M.S.)--Florida State University, 2003. / Advisor: Dr. Susan Davis Allen, Florida State University, College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed Apr. 12, 2004). Includes bibliographical references.

Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, September 2003. / Thesis advisor(s): Philip A. Durkee, Carlyle H. Wash. Includes bibliographical references (p. 49-51). Also available online.

A research report submitted to the Faculty of Science, University of the Witwatersrand in fulfilment of the requirements for the degree of Master of Science, Johannesburg, August, 2014. / Efflorescent minerals are a common feature of the soil surface in seasonal environments where evapotranspiration (ET) exceeds precipitation (P), and are formed by the evaporation of salt solutions from the soil during periods of drying. On the Highveld gold fields, ET exceeds rainfall by approximately two-and-a-half times during the dry season, and soils overlying acid mine drainage and along polluted stream banks can become covered by distinctively coloured mineral efflorescent crusts. Whereas some efflorescent minerals are relatively insoluble and present a negligible environmental hazard (for example, gypsum), others may be readily soluble and contain high concentrations of potentially toxic metals (for example, copiapite, jarosite and uranyl sulphate). During periods of rainfall, such salts are washed further afield and into surface water bodies and act as sources of episodic pollution. The presence of some efflorescent minerals can be detected from their characteristic reflectance signatures using remote-sensing (RS) of the electromagnetic spectrum. The species of efflorescent minerals present is a useful indication of the spatial extent of sub-surface contamination, and also of the chemical conditions of the substrate, in particular the concentration of total dissolved solids, pH and redox conditions. The aim of this study was therefore to assess the use of remote-sensing on indicator efflorescent minerals as a cost-effective aid in the spatial mapping of acid rock-drainage polluted soils and water-bodies. This study describes the range of efflorescent crusts identified on different land-use areas and soil classes in a Highveld gold-mining region. Crusts were first measured in-situ under natural sunlight using a portable analytical spectral radiometer (ASD) as well as using X-ray diffraction (XRD). They were then dissolved in deionized water and the resulting salt solutions allowed to evaporate prior to analysis under controlled lighting conditions. Spectra were post-processed and compared with iv geological spectral reference libraries. The salt solutions were also analyzed for metal and sulphate content and the results were used to establish evaporation models from which mineral precipitation could be predicted. Minerals identified in the visible near-infra red (VNIR) region included iron oxides (hematite and goethite), and the sulphate mineral jarosite. In the short wave infra-red (SWIR) region clay minerals of the smectite group were dominant. Gypsum and Al-Mn-Mg-Na sulphate salts were identified in the SWIR region as mixtures occurring with clay minerals. Minerals identified in the VNIR-SWIR region were all confirmed by X-Ray diffraction (XRD). Upon dissolution, geochemical modeling revealed that gypsum and jarosite are the most common minerals expected to precipitate. The precipitation of gypsum and jarosite indicates persistent acidic conditions after dissolution of mineral salts. Gypsum and jarosite were also accurately identified by hyper-spectral spectroscopy and confirmed by XRD and geochemical modeling. Agreement between spectral interpreted minerals and geochemically precipitated mineral phases demonstrated the ability of hyper-spectral data in detecting efflorescence minerals on the soil surface. Using partial least squares regression (PLSR) combined with bootstrapping, reflectance spectrum was significantly correlated with geochemical variables.

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Mechanical and Aerospace Engineering." Includes bibliographical references (p. 63-67).

Orientador: Ana Marisa Fusco-Almeida / Coorientador: Francisco Javier Enguita / Banca: Eloisa aparecida Mocheuti Kronka / Banca: Daniel Guariz Pinheiro / Banca: Eleini Gomes / Banca: Tais Maria Bauab / Resumo: O processo de fermentação é amplamente utilizado em usinas brasileiras para produção de bioetanol e, mesmo sendo um processo amplamente difundido, a problemática sobre contaminações por micro-organismos ainda é uma incógnita. Problemas de redução de produtividade estão diretamente ligados à competição de nutrientes quando há decorrentes crises de contaminações por bactérias e leveduras não-Saccharomyces. Entre as leveduras contaminantes mais encontradas estão as pertencentes aos gêneros Candida, Torulopis, Rhodotorula, Pichia, Komagataella e Schizosaccharomyces. Muitos antimicrobianos são utilizados para combater contaminações, porém com baixas especificidade e eficiência para leveduras contaminantes. O desenvolvimento de novas alternativas para a descontaminação do processo fermentativo e a busca por biomoléculas naturais e não geradoras de resíduos tóxicos, são emergenciais. Tais biomoléculas podem ser originárias dos miRNAs, que são pequenas moléculas de RNA não codificantes que afetam a estabilidade dos RNAs mensageiros, atuando na expressão de transcritos dentro de processos biológicos, afetando controles transcricionais e pós-transcricionais, resultando na inibição ou potencialização da ação gênica nos processos biológicos fermentativos. Dessa forma, miRNAs livres na dorna de fermentação podem interferir de maneira controlada os contaminantes que competem com a levedura Saccharomyces cerevisiae na produção de bioetanol. Em estudos anteriores de nosso grupo foi seleciona... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The fermentation process is widely used in Brazilian plants for the production of bioethanol and, even though it is a widely diffused process, the problem of contamination by microorganisms is still unknown. Productivity reduction problems are directly linked to nutrient competition when there are bouts of contamination by bacteria and non-Saccharomyces yeasts. Among the most common contaminating yeasts are those belonging to the genera Candida, Torulopis, Rhodotorula, Pichia, Komagataella and Schizosaccharomyces. Many antimicrobials are used to combat contamination, but with low specificity and efficiency for contaminating yeasts. The development of new alternatives for the decontamination of the fermentative process and the search for natural biomolecules and non-toxic wastes are emergency. Such biomolecules may originate from the miRNAs, which are small molecules of non-coding RNA that affect the stability of messenger RNAs, acting on the expression of transcripts within biological processes, affecting transcriptional and post-transcriptional controls, resulting in the inhibition or potentiation of the gene action fermentative biological processes. Thus, free miRNAs in the fermentation dorna can interfere in a controlled manner the contaminants that compete with the yeast Saccharomyces cerevisiae in the production of bioethanol. In previous studies of our group, a contaminant strain of Candida tropicalis, isolated from a plant in the region of Araraquara/SP, was selected and studied, which persevered during the period of one harvest. As a continuity, our study aimed to elucidate the metabolic and transcriptional behavior of the relevant contaminant, C. tropicalis, during the fermentation cycle, through fermentative capacity techniques, sequencing of global RNA and to identify target genes for the development of miRNAs as antifungal biomolecules... (Complete abstract click electronic access below) / Doutor

The effects of contaminated supply air on the performance of a laminar proportional amplifier were experimentally investigated. The air supply was contaminated with oil vapor and particulate matter. Characteristic gain curves were obtained after each stage of contamination for various loading conditions. Photographs showing the location of contaminant deposits were taken. Two inlet geometries were studied: right-angle and straightthrough. The effects of maintaining a constant pressure and constant flow rate at the inlet throughout the duration of the tests were studied. Also, aspect ratio effects. were studied. Rapid deterioration of performance was evident with the right-angle entry due to inlet blockage. By milling a cavity in the bottom cover plate, the detrimental effects of inlet blockage were delayed. With constant pressure inlet conditions and straight-through geometry, significant buildup occurred in the nozzle region and downstream. Decrease in pressure recovery was linear with time. It was determined that null shift was caused by asymmetric buildup in either the nozzle region or splitter region. With constant flow inlet conditions, the damaging effects on performance were delayed for both inlet geometries. Also, for the straight-through inlet, the nozzle region was relatively clean when compared with the constant pressure inlet case. Null shift was found to be the result of asymmetric buildup in the downstream region. At lower aspect ratios, the damaging effects of contamination were more severe and occurred in less time. / Master of Science

Detection of ultratrace levels of metallic ion impurities in hydrofluoric acid solutions and alkaline hydrogen peroxide solution was demonstrated using a silicon-based sensing electrode. The sensor's operation principle is based on direct measurements of the silicon open-circuit potential shift generated by the interaction between metallic ions and the silicon-based sensing surface. The new sensor can have practical applications in the on-line monitoring of microelectronic chemical processing. The detection of Ag+ content in KODAK waste water was carried out successfully by this novel sensor. Trace levels of organic impurities in the hydrofluoric acid solutions and in the cleanroom air were characterized by multiple internal reflection infrared spectroscopy (MIRIS) using an organics probe prepared directly from a regular silicon wafer.

Thesis (Ph.D.) -- University of Western Sydney, 2004. / Includes bibliography.