Self-purification of aquatic media from hexachlorocyclohexane in a radical process
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Ecologie generală şi biodiversitate (247)
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TRAVIN, Serghei; DUCA, Gheorghe; GLADCHI, Viorica. Self-purification of aquatic media from hexachlorocyclohexane in a radical process. In: Chemistry Journal of Moldova. 2019, nr. 1(14), pp. 47-53. ISSN 1857-1727.
10.19261/cjm.2018.537
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Chemistry Journal of Moldova
Numărul 1(14) / 2019 / ISSN 1857-1727 /ISSNe 2345-1688

Self-purification of aquatic media from hexachlorocyclohexane in a radical process


CZU: 574.4:54
DOI: 10.19261/cjm.2018.537
Pag. 47-53

Travin Serghei1, Duca Gheorghe23, Gladchi Viorica4
 
1 N.N. Semenov Institute of Chemical Physics, Russian Academy of Sciences,
2 Institute of Chemistry,
3 Academy of Sciences of Moldova,
4 State University of Moldova
 
Disponibil în IBN: 8 iulie 2019


Rezumat

It is known, that highly toxic pesticide hexachlorocyclohexane (HCH) is resistant to decomposition and has a long-term accumulating capacity. Nevertheless, it undergoes complete degradation in reactions with hydroxyl radicals in Fenton-like systems. The goal of this work was to study the influence of HCH on the processes of radical self-purification of water bodies and to explain the mechanisms of chemical transformation of substances occurring in natural waters, as well as to reveal the kinetic characteristics of the processes of radical self-purification of water bodies. It was found, that HCH plays a dual role for aquatic ecosystems – it is not only a scavenger of free radicals, but also an additional initiator. Under the influence of light in the surface layer of water, HCH generates radicals, thus contributing to the self-purification processes.

Cuvinte-cheie
hexachlorocyclohexane, natural water, radical self-purification, kinetic characteristic

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<creators>
<creator>
<creatorName>Vîrlan, C.</creatorName>
<affiliation>Universitatea de Stat de Medicină şi Farmacie „Nicolae Testemiţanu“, Moldova, Republica</affiliation>
</creator>
<creator>
<creatorName>Bondarevskaia, N.</creatorName>
<affiliation>Universitatea de Stat de Medicină şi Farmacie „Nicolae Testemiţanu“, Moldova, Republica</affiliation>
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<creator>
<creatorName>Granciuc, G.N.</creatorName>
<affiliation>Universitatea de Stat de Medicină şi Farmacie „Nicolae Testemiţanu“, Moldova, Republica</affiliation>
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<titles>
<title xml:lang='en'><p>Cephalometric investigation of class III malocclusion according to McNamara method</p></title>
</titles>
<publisher>Instrumentul Bibliometric National</publisher>
<publicationYear>2013</publicationYear>
<relatedIdentifier relatedIdentifierType='ISBN' relationType='IsPartOf'>978-9975-62-343-8.</relatedIdentifier>
<subjects>
<subject>Lateral teleradiography</subject>
<subject>cephalometric analysis</subject>
<subject>McNamara</subject>
<subject>Class III malocclusion</subject>
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<date dateType='Issued'>2013</date>
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<description xml:lang='en' descriptionType='Abstract'><p>Lateral teleradiography represents an indispensable paraclinical investigation in dento-maxillary anomalies. McNamara&rsquo;s cephalometric analysis method is one of the most suitable in this case. The purpose of this study was to identify the most informative parameters according to McNamara method, that are specific for Class III malocclusion. The study sample consists of 6 lateral cephalometric radiograms that were examined according to principles described by McNamara. After cephalometric evaluation we detected a range of modifications characteristic for Class III. The mandible is positioned more antero-inferior than the normal values suggested by McNamara, which is confirmed by an average deviation of 6.7mm of the index Pg-Nasion perpendicular. There was detected a significant antero-posterior skeletal disharmony, proven by increased values (15.6mm) of the variable maxillomandibular difference. The maxilla has a retropositioned location compared to the cranial base expressed by the parameter A-Nasion perpendicular that is deviated 4.2mm posterior from the position considered normal. The goniac angle is more obtuse than the standard values. The increased value (+3.2&deg;) of the angle between Frankfurt and mandibular plane confirms this modification. Mandibular length was excessive for all the patients with a medium exceed of the normal values of 13.1mm. As a result of this research we determined that the most important informative value in class III diagnosis is possessed by the following parameters: the mandibular and maxillary length, maxillomandibular difference, the relation between the mandible and cranial base and the goniac angle value.</p></description>
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