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331.
332.
Fabíola Maria N. Nunes M.C.C. Veloso P.A. de P. Pereira J.B. de Andrade 《Atmospheric environment (Oxford, England : 1994)》2005,39(40):927
Biogenic emissions of volatile organic compounds (VOCs) play a fundamental role in atmospheric chemistry. Vegetation is the most abundant natural source of VOCs, while terpenoids, as limonene, α and β pinene and mircene, top the plants emission list. Much interest has been demonstrated in oxidation and photooxidation reactions of VOCs, particularly of monoterpenoids, owing to their diversity and to uncertainties regarding their mechanism of reaction. Quantification of primary carbonylic compounds, as well as of biradical reaction components, is highly relevant to the understanding of the major reactions. In this context, taking into account both structural factors and the fact that these compounds are found in the essential oils of plants typically found in Brazil and that they may be present in the atmosphere from emission by the plants, the monoterpenoids (S)-(+)-carvone, (R)-(−)-carvone, (−)-carveol, geraniol and citral (a mixture of the isomers geranial and neral) were selected for this study.The ozonolysis reactions of the monoterpenoids were carried out under dark conditions for all experiments, due to their photochemical reactivity. The analysis of the results lets us propose a mechanism by which these reactions occur. The observed results of the ozonolysis of S and R carvone suggest that the stereochemistry of asymmetric carbon does not affect either in the yields of both formaldehyde and of OH radicals produced in the reaction, or in the reactivity of these compounds, for which the rate constants were in the scale of 10−6 s−1.We found that, in the (−)-carveol's cis and trans mixture, even though the hydroxyl in the axial position—in the case of trans-(C) and cis-(D′) isomers—favors the attack by the ozone molecule on the external double bond, thus increasing the mixture's reactivity , it affects the average production of formaldehyde. The presence of geraniol and citral led to the production of formaldehyde, propanone, glyoxal, methyl–glyoxal and cyclohexanone (OH radicals) as reaction products. The influence of an electron attractor group bonded to the carbon of the double bond, on the reactivity of the double bond, could not be observed in the case of citral, due to strong interference occurring in the instrument in all experiments with this monoterpenoid. For this reason, only the kinetics of geraniol was monitored . 相似文献
333.
Susana L. H. Rebelo A. Melo R. Coimbra M. Emília Azenha Mariette M. Pereira Hugh D. Burrows Mohamed Sarakha 《Environmental Chemistry Letters》2007,5(1):29-33
The photodegradation of the herbicides atrazine and ametryn with visible light in aerated neutral aqueous solutions and 5,
10, 15, 20-tetrakis (2,6-dichloro-3-sulfophenyl) porphyrin or 5, 10, 15, 20-tetrakis (4-sulfophenyl) porphyrin as sensitizers
are reported for the first time. Our findings show that the degradation percentage reached 30% for atrazine and 63% for ametryn.
The final photoproducts were characterized as dealkylated s-triazines. Photolysis of the pesticides in the presence of a singlet oxygen quencher showed only a minor contribution of
this type of mechanism, while a bimolecular quenching reaction between the triplet state of the sensitizer and the pesticides
is excluded by flash photolysis studies. It is proposed that the mechanism may involve the formation of a superoxide radical
anion from the triplet state of the sensitizer and molecular oxygen, followed by a radical decomposition pathway.
Selected article from 1st International Meeting on Photochemistry, Photocatalysis and Environmental Applications, Agadir,
2006, organised by Prof. Dr. Ait Ichou, University Ibn Zohr, Agadir, Morocco 相似文献
334.
Maria do Socorro S. Pereira Eduardo Winter Jose Roberto Guimarães Susanne Rath Anne Hélène Fostier 《Environmental Chemistry Letters》2007,5(3):137-141
Here, we show a fast and sensitive method for the determination of inorganic arsenic in natural waters using differential
pulse cathodic stripping voltammetry. All the arsenite determinations were done in 2.0 mol L−1 HCl + 3.15 × 10−4 mol L−1 Cu(II) supporting electrolyte. 1 × 10−3 mol L−1 sodium thiosulphate was used as As(V) reducing agent. The detection limit was 0.5 μg L−1 for both species. The method has been applied to water samples collected in an arsenic-contaminated region of Brazil, in
particular, to verify the efficiency of the solar oxidation and removal of arsenic process applied to these waters. 相似文献
335.
Harold G. Fowler Maria Inez Pagani Osvaldo Aulino Da Silva Luis Carlos Forti Virgilio Pereira Da Silva Heraldo Luis De Vasconcelos 《Environmental management》1989,13(6):671-675
Leaf-cutting ants of the generaAcromyrmex andAtta are considered the principal polyphagous pests of the Neotropics Although some members of these genera are of economic importance, have a broad geographic distribution, and are extremely good colonizers, others are endemic and closely interact with native ecosystems. Control is generally practiced against any colony, irrespective of its taxonomic status. Indiscriminate control coupled with habitat destruction threatens endemic species with extinction, and, through habitat simplification, favors other pest species. As nests ofAtta are large, having several square meters of nest surface, the endemic taxa can be easily used as environmental indicators for natural ecosystems Likewise, the pest species can be used to detect environmental disturbance As these ants are keystone species and easily identified by nonspecialists, efforts should be made to integrate these into viable conservation programs 相似文献
336.
Helen Carnaghan Catherine P. James Paul B. Charlesworth Marco Ghionzoli Susana Pereira Mohamed Elkhouli David Baud Paolo De Coppi Greg Ryan Prakesh S. Shah Mark Davenport Anna L. David Agostino Pierro Simon Eaton Gastroschisis Study Group 《黑龙江环境通报》2020,40(8):991-997
Objective
In gastroschisis, there is evidence to suggest that gut dysfunction develops secondary to bowel inflammation; we aimed to evaluate the effect of maternal antenatal corticosteroids administered for obstetric reasons on time to full enteral feeds in a multicenter cohort study of gastroschisis infants.Methods
A three center, retrospective cohort study (1992-2013) with linked fetal/neonatal gastroschisis data was conducted. The primary outcome measure was time to full enteral feeds (a surrogate measure for bowel function) and secondary outcome measure was length of hospital stay. Analysis included Mann-Whitney and Cox regression.Results
Of 500 patients included in the study, 69 (GA at birth 34 [25-38] weeks) received antenatal corticosteroids and 431 (GA at birth 37 [31-41] weeks) did not. Antenatal corticosteroids had no effect on the rate of reaching full feeds (Hazard ratio HR 1.0 [95% CI: 0.8-1.4]). However, complex gastroschisis (HR 0.3 [95% CI: 0.2-0.4]) was associated with an increased time to reach full feeds and later GA at birth (HR 1.1 per week increase in GA [95% CI: 1.1-1.2]) was associated with a decreased time to reach full feeds.Conclusion
Maternal antenatal corticosteroids use, under current antenatal steroid protocols, in gastroschisis is not associated with an improvement in neonatal outcomes such as time to full enteral feeds or length of hospital stay. 相似文献337.
The present study assesses the sustainability of ethanol produced from sugarcane and examines the environmental feasibility of a large-scale production through the use of: fossil fuel embodied energy and Emergy Assessment including farm and industrial production phases. The study indicates that about 1.82 kg of topsoil eroded, 18.4 l of water and 1.52 m2 of land are needed to produce 1 l of ethanol from sugarcane. Also, 0.28 kg of CO2 is released per liter of ethanol produced. The energy content of ethanol is 8.2 times greater than the fossil-based energy required to produce it. The transformity of ethanol is about the same as those calculated for fossil fuels. The Renewability of ethanol is 30%, a very low value; other emergy indices indicate important environmental impacts as well as natural resources consumption. The results obtained indicate that sugarcane and ethanol production present low renewability when a large-scale system is adopted. 相似文献
338.
Dielle Monteiro Teixeira Juliana Merces Hernandez Luciana Damascena Silva Darleise de Souza Oliveira Paula Katharine de Pontes Spada Tereza Cristina Monteiro Gurjão Joana D’Arc Pereira Mascarenhas Alexandre Costa Linhares Lena Líllian Canto de Sá Morais Yvone Benchimol Gabbay 《Food and environmental virology》2016,8(1):101-104
Noroviruses are the major cause of non-bacterial acute gastroenteritis outbreaks in humans, with few reports about the occurrence of the norovirus GIV strain. We investigated the presence of norovirus GIV in surface water (river, bay, and stream) and untreated sewage, and we determined a positivity rate of 9.4 % (9/96). The strains genotyped were GIV.1. To our knowledge, this is the first report of GIV in Brazil. 相似文献
339.
340.
Shany?Mayumi?NagaokaEmail author Agnaldo?Silva?Martins Robson?Guimar?es?dos?Santos M?nica?Maria?Pereira?Tognella Eurico?Cabral?de?Oliveira Filho Jeffrey?A.?Seminoff 《Marine Biology》2012,159(3):573-581
The diet of 50 juvenile green turtles Chelonia mydas live-captured incidentally by fixed fishing traps between January and June 2009 in Cananéia Estuarine–Lagoon complex, Brazil,
was studied through analysis of esophageal lavage samples. Green turtles consumed an omnivorous diet, with 18 food components
identified and grouped into 4 categories as follows: terrestrial plants, algae, invertebrates, and seagrass. Black mangrove
leaves were of the greatest importance to diet. Turtles incidentally get into fixed traps probably because these devices are
located on mangrove margins, where they forage. The additional foods suggest that green turtles also feed opportunistically
on material adhered to the trap structure and/or on items that cross into its interior. Green turtle diet in estuarine environments
appears to be determined by the availability of food components, with some selectivity toward items of apparently greater
nutritional value. 相似文献