Volatile organic compounds

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  • Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học 'Respiratory Research cung cấp cho các bạn kiến thức về ngành y đề tài:" Exhaled volatile organic compounds in patients with non-small cell lung cancer: cross sectional and nested short-term follow-up study...

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  • The complexity of the volatile organic compound (VOC) mixture in the Houston area makes studies of the air quality in that area very challenging. In this paper, a novel factor analysis model, where the normal chemical mass balance model was augmented by a parallel equation that accounted for wind speed and direction, temperature, and weekend/weekday effects, was fitted with a multilinear engine (ME) to provide identification and apportionment of the VOC sources at the La Porte Municipal Airport site in Houston during the Texas Air Quality Study (TexAQS) 2000.

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  • Hydrogen peroxide is a strong oxidant that can be injected into a contaminated zone to destroy petroleum contaminants. When injected to groundwater, hydrogen peroxide is unstable, and reacts with organic contaminants and subsurface materials. It decomposes to oxygen and water within hours of its introduction into groundwater generating heat in the process. Peroxide is typically shipped to a remediation site in liquid form at dose concentrations ranging from five percent to 50 percent by weight.

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  • Food purchasing is an important expression of food habits. This paper therefore examines the factors associated with a household’s decision to purchase organic food products because such information is not yet available for the study area despite anecdotal evidence of the growing importance of organic products in the country. A randomly chosen sample of 200 consumers in rural and urban areas of the province’s two major regions, the former Ciskei and Transkei homeland areas, were enumerated.

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  • The European Union has developed the draft of a “Working document on sludge” (EU 2000), to promote the use of sewage sludge in agriculture while improving the safety and harmonize quality standards. It proposes limit values for concentrations of heavy metals and organic compounds that should restrict the use of sewage sludge in agriculture if the limits are exceeded and provides suggestions for good practice in treatment and agricultural use.

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  • The history, culture and community values of East Africans are embedded in agriculture. It is the most important source of livelihoods for millions of East Africans. The sustainable management of the agriculture production process is therefore crucial if livelihoods are to be sustained. Organic agriculture is a holistic production management system, which promotes and enhances agro- ecosystem health, including bio-diversity, biological cycles and soil biological activity.

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  • Concurrent treatment of source area saturated and unsaturated zones usually requires the integration of chemical oxidation with other remedial technologies that target unsaturated zone contamination (e.g., soil vapor extraction). Frequently, soil vapor extraction, which is used to treat the unsaturated zone, is included as a component of chemical oxidation remedial solutions even if there is no specific need to treat unsaturated soils in the source area.

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  • The current global epidemic of pulmonary tuberculosis has highlighted the need for new screening tests that are rapid and accurate. The social burden of pulmonary tuberculosis has increased because many patients are also infected with human immunodeficiency virus (HIV), and the rates of multidrug-resistant tuberculosis are increasing.1 However, screening technology has not changed greatly during the past several decades. Many highburden countries depend upon sputum smears and chest radiographs, supplemented by cultures when resources permit.

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  • A study to measure indoor concentrations and emission rates of volatile organic compounds (VOCs), including formaldehyde, was conducted in a new, unoccupied manufactured house installed at the National Institute of Standards and Technology (NIST) campus. The house was instrumented to continuously monitor indoor temperature and relative humidity, heating and air conditioning system operation, and outdoor weather. It also was equipped with an automated tracer gas injection and detection system to estimate air change rates every 2 h.

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  • The chemistry of fine organic intermediates and products shows an enormous diversity. But in reality, the number of operations/processes used remains reasonably small. These include charging/discharging of reactants and solvents, inertisation, reactions, crystallisations, phase separations, filtrations, distillation, product washing. In many cases cooling, heating, or the application of vacuum or pressure is necessary. The unavoidable waste streams are treated in recovery/abatement systems or disposed of as waste.

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  • Analysis was conducted on nutrients or nutrient groups for which numeric data were provided in at least 10 of the 137 crop studies identified by the review.

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  • Microorganisms associated with the production of volatile compound in spoilt mango fruits sold in Sokoto town were isolated and identified. The organisms include seven species of bacteria and a species of yeast. These include Bacillus pumilus, Bacillus firmus, Brevibacillus laterosporus, Morganella morganii, Paenibacillus alvei, Staphylococcus saccharolyticus, Listeria monocytogenes and Candida krusei respectively. GC-MS analysis revealed the presence of eleven and sixteen volatile organic compound in the healthy and spoilt ripe mango fruits.

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  • Petroleum contaminant decomposition and in-situ destruction may be accomplished using chemical oxidation technologies. In contrast to other remedial technologies, contaminant reduction can be seen in short time frames (e.g., weeks or months). As discussed in this chapter, a variety of chemical oxidants and application techniques can be used to bring oxidizing materials into contact with subsurface contaminants to remediate the contamination.

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  • Regioregular polythiophene-based conductive copolymers with highly crystalline nanostructures are shown to hold considerable promise as the active layer in volatile organic compound (VOC) chemresistor sensors. While the regioregular polythiophene polymer chain provides a charge conduction path, its chemical sensing selectivity and sensitivity can be altered either by incorporating a second polymer to form a block copolymer or by making a random copolymer of polythiophene with different alkyl side chains.

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  • Consequently the chemical contamination builds to higher levels in these organisms. Indigenous peoples in the Arctic, whose traditional diets are heavy in fatty foods and who often have no alternatives for nourishment, thus have some of the highest recorded levels of POPs. Yet they are hundreds or thousands of kilometres from where these pesticides and industrial chemicals were released, and they certainly received little benefit from the chemicals' original use.

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  • Organic systems are more labor intensive than conventional systems. This higher labor requirement is most often attributed to the increased time monitoring and managing pests. Washington State research statistics indicate that labor hours per acre can be as much as 11% higher for agronomic crops. The increase can be much greater for horticultural crops. Economic Considerations Organic crops can receive price premiums of anywhere from 10% to 200% (or more) over conventionally grown products, according to the USDA Economic Research Service.

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  • EPA Region 9 has developed technical guidelines to help ensure that sampling and analyzing for Volatile Organic Compounds (VOCs) in soil and solid matrices are conducted in a manner that achieves accurate, technically defensible data. Region 9’s guidelines, which are intended to apply whenever VOC sampling in and analysis of soil and solid matrices are conducted, are consistent with United States Environmental Protection Agency (USEPA) Office of Solid Waste test methods.

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  • Indoor exposures to toxic and irritating volatile organic compounds (VOCs) are of general concern. Residences are particularly important exposure environments for these compounds because people in the U.S.A. spend an average of 69 % of their time indoors at home (Klepeis et al., 2001). In addition, residential ventilation rates, which serve as the primary mechanism for removal of gaseous pollutants generated indoors, are relatively low. The median air change rate measured in the 1980s for a large number of houses in the United States was 0.

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  • Pollution prevention. IPPC presumes the use of preventative techniques before any consideration of end-of-pipe control techniques. Many pollution prevention techniques can be applied to LVOC processes and Section 5.2 describes them in terms of source reduction (preventing waste arisings by modifications to products, input materials, equipment and procedures), recycling and waste minimisation initiatives. Air pollutant control.

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  • People of four generations ago lived at the turn of the 20th Century, before the invention and widespread use in agriculture and industry of thousands of synthetic chemicals. Those of us living in the early 21st Century inhabit a world where some of these substances – which were introduced as far back as the 1920s and employed more and more in the 1940s and '50s – have been around for decades. Now they are everywhere . . . including in the tissues of every human being on Earth.

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