ОХИ, пуферскиот капацитет на плунката како ризик фактори на кариес

Кариесот денес без разлика на средствата и методите кои се нудат за негово делотворно спречување, сепак истиот е еден од најраспространетите заболувања

Determination of dimethoate, 2,4-dichlorophenoxy acetic acid, mecoprop and linuron pesticides in environmental waters in R. Macedonia by high-performance liquid chromatography

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Investigation of the mechanism of degradation of the azinphos-methyl herbicide using HPLC/DAD/ESI-MSN

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Investigation of the mechanism of degradation of the azinphos-methyl herbicide using HPLC/DAD/ESI-MSN

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Theoretical and experimental approach for the study of 2,4-dichlorophenoxyacetic acid photodegradation: C-O versus C-Cl bond dissociation energies in the gas phase and aqueous medium

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Degradation and mineralization of sulcotrione and mesotrione in aqueous medium by the electro-Fenton process: a kinetic study

International audienceIntroduction: The degradation and mineralization of two triketone (TRK) herbicides, including sulcotrione and mesotrione, by the electro-Fenton process (electro-Fenton using Pt anode (EF-Pt), electro-Fenton with BDD anode (EF-BDD) and anodic oxidation with BDD anode) were investigated in acidic aqueous medium. Methods: The reactivity of both herbicides toward hydroxyl radicals was found to depend on the electron-withdrawing effect of the aromatic chlorine or nitro substituents. The degradation of sulcotrione and mesotrione obeyed apparent first-order reaction kinetics, and their absolute rate constants with hydroxyl radicals at pH 3. 0 were determined by the competitive kinetics method. Results and discussion: The hydroxylation absolute rate constant (kabs) values of both TRK herbicides ranged from 8. 20 × 108 (sulcotrione) to 1. 01 × 109 (mesotrione) L mol-1 s-1, whereas those of the TRK main cyclic or aromatic by-products, namely cyclohexane 1,3-dione, (2-chloro-4-methylsulphonyl) benzoic acid and 4-(methylsulphonyl)-2-nitrobenzoic acid, comprised between 5. 90 × 108 and 3. 29 × 109 L mol-1 s-1. The efficiency of mineralization of aqueous solutions of both TRK herbicides was evaluated in terms of total organic carbon removal. Mineralization yields of about 97-98% were reached in optimal conditions for a 6-h electro-Fenton treatment time. Conclusions: The mineralization process steps involved the oxidative opening of the aromatic or cyclic TRK by-products, leading to the formation of short-chain carboxylic acids, and, then, of carbon dioxide and inorganic ions

Application of the electro-Fenton process to mesotrione aqueous solutions: kinetics, degradation pathways, mineralization and evolution of the toxicity

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All-cis 1,2,3,4,5,6-hexafluorocyclohexane is a facially polarized cyclohexane

This work was generously supported by the Engineering and Physical Sciences Research Council (EPSRC) and the European Research Council (ERC).The highest-energy stereoisomer of 1,2,3,4,5,6-hexafluorocyclohexane, in which all of the fluorines are ‘up’, is prepared in a 12-step protocol. The molecule adopts a classic chair conformation with alternate C–F bonds aligned triaxially, clustering three highly electronegative fluorine atoms in close proximity. This generates a cyclohexane with a high molecular dipole (μ = 6.2 D), unusual in an otherwise aliphatic compound. X-ray analysis indicates that the intramolecular Fax···Fax distances (∼2.77 Å) are longer than the vicinal Fax···Feq­ distances (∼2.73 Å) suggesting a tension stabilizing the chair conformation. In the solid state the molecules pack in an orientation consistent with electrostatic ordering. Our synthesis of this highest-energy isomer demonstrates the properties that accompany the placement of axial fluorines on a cyclohexane and the unusual property of a facially polarized ring in organic chemistry. Derivatives have potential as new motifs for the design of functional organic molecules or for applications in supramolecular chemistry design.PostprintPeer reviewe