نتایج جستجو برای: natural contamination

تعداد نتایج: 530979  

2006
M. Ávila

Control of surface contamination in the form of small particles is becoming a major priority in conventional manufacturing processes, due to the higher sensitivity of mechanical assemblies to contamination-related failures. At the same time, the complexity of workpieces is increasing, making the removal of contaminants more difficult. Thus there is a critical need to facilitate cleaning in orde...

Journal: :Journal of hazardous materials 2011
C Lafabrie K M Major C S Major M M Miller J Cebrián

The overarching goal of this in situ study was to investigate the integrated impact(s) that metal/metalloid contamination might have on the overall health and performance of the ecologically important aquatic macrophyte, Vallisneria neotropicalis. Morphological (i.e., shoot growth-based endpoints) and photo-physiological (i.e., photosynthetic activity measured as chlorophyll a fluorescence and ...

2009
Liliana O. Rocha Viviane K. Nakai Raquel Braghini Tatiana A. Reis Estela Kobashigawa Benedito Corrêa

Natural mycoflora and co-occurrence of fumonisins (FB(1), FB(2)) and aflatoxins (AFB(1), AFB(2), AFG(1) and AFG(2)) in freshly harvested corn grain samples from four regions of Brazil were investigated. Fusarium verticillioides was predominant in all samples. Analysis of fumonisins showed that 98% of the samples were contaminated with FB(1) and 74.5% with FB(1) + FB(2), with toxin levels rangin...

Journal: :Applied and environmental microbiology 1989
C Tartera F Lucena J Jofre

Bacteroides fragilis HSP40 phages have been detected in waters with various levels of fecal contamination of human origin. The average numbers of B. fragilis phages present in sewage water reached 5.3 x 10(3) per 100 ml of water. We found a number 1,000 times lower in a river contaminated with domestic sewage only, in which the levels of fecal coliforms and fecal streptococci were 10,000 times ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان 1390

abstract the influence of cation?? and anion?? interactions on the strength and nature of n…h hydrogen bond has been investigated by quantum chemical calculations in s-triazine…3hf complex. ab initio calculations were performed at mp2/6-311++g(d,p) level of theory. the natural bond orbital (nbo) analysis and the bader’s quantum theory of atoms in molecules (aim) were also used to elucidate t...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2014
Thomas H Darrah Avner Vengosh Robert B Jackson Nathaniel R Warner Robert J Poreda

Horizontal drilling and hydraulic fracturing have enhanced energy production but raised concerns about drinking-water contamination and other environmental impacts. Identifying the sources and mechanisms of contamination can help improve the environmental and economic sustainability of shale-gas extraction. We analyzed 113 and 20 samples from drinking-water wells overlying the Marcellus and Bar...

Journal: :مجله انسان، محیط زیست و ارتقاء سلامت 0
tooran yarahmadi zanjan, parvin eatesami bolv., school of health and paramedical hassan hassanzadaza zanjan, parvin eatesami bolv., school of health and paramedical sajad chamandoost zanjan, parvin eatesami bolv., school of health and paramedical majid aminzarer zanjan, parvin eatesami bolv., school of health and paramedical

background; foods have been many changes from production to tables and continuous control is necessary to maintain food safety and supply foods with good quality. the aim of this study was to evaluate the quality of some foods with high consumption in zanjan city during the 5 years from 2009 to 2013. methods; in a case-control descriptive study with an annually control program during 5 years fr...

2000
H. A. J. Meijer R. E. M. Neubert G. H. Visser

Since the early days of geochemical isotope ratio mass spectrometry there has always been the problem of cross contamination, i.e. the contamination of the sample gas with traces of reference gas (and vice versa) in a dual inlet system and the analyzer itself. This was attributable to valve leakages and could be corrected for. In modern leak-free machines this problem still influences the measu...

Journal: :J. Economic Theory 2009
Subir Bose Arup Daripa

We study the question of auction design in an IPV setting characterized by ambiguity. We assume that the preferences of agents exhibit ambiguity aversion; in particular, they are represented by the epsilon-contamination model. We show that a simple variation of a discrete Dutch auction can extract almost all surplus. This contrasts with optimal auctions under IPV without ambiguity as well as wi...

2009
Jason L. Sonnenberg Bernhard Schlegel Hrant P. Hratchian

An overview of spin contamination and its relationship to broken-symmetry wave functions are presented. Spinoperator expectation-value formulas are developed for use with generalized, unrestricted, and restricted spin orbitals. Currentprojection techniques are reviewed and illustrated for a variety of current theoretical methods.

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