Organic Derivatives of Mercury and Tin as Promoters of Membrane Lipid Peroxidation

The toxicity mechanisms of mercury and tin organic derivatives are still under debate. Generally the presence of organic moieties in their molecules makes these compounds lipophilic and membrane active species. The recent results suggest that Hg and Sn compounds deplete HS-groups in proteins, glutathione and glutathione-dependent enzymatic systems; this process also results in the production of reactive oxygen species (ROS), the enhancement of membrane lipids peroxidation and damage of the antioxidative defence system. The goal of this review is to present recent results in the studies oriented towards the role of organomercury and organotin compounds in the xenobiotic-mediated enhancement of radical production and hence in the promotion of cell damage as a result of enhanced lipids peroxidation. Moreover the conception of the carbon to metal bond cleavage that leads to the generation of reactive organic radicals is discussed as one of the mechanisms of mercury and tin organic derivatives toxicity. The possible use of natural and synthetic antioxidants as detoxification agents is described. The data collected recently and presented here are fundamentally important to recognizing the difference between the role of metal center and of organic fragments in the biochemical behavior of organomercury and organotin compounds in their interaction with primary biological targets when entering a living organism

Người tình của Makxim Gorky

609 tr. ; 21 cm

A Biscriptual Morphological Transducer For Crimean Tatar

This paper describes a weighted finite-state morphological transducer for Crimean Tatar able to analyse and generate in both Latin and Cyrillic orthographies. This transducer was developed by a team including a community member and language expert, a field linguist who works with the community, a Turkologist with computational linguistics expertise, and an experienced computational linguist with Turkic expertise. Dealing with two orthographic systems in the same transducer is challenging as they employ different strategies to deal with the spelling of loan words and encode the full range of the language\u27s phonemes and their interaction. We develop the core transducer using the Latin orthography and then design a separate transliteration transducer to map the surface forms to Cyrillic. To help control the non-determinism in the orthographic mapping, we use weights to prioritise forms seen in the corpus. We perform an evaluation of all components of the system, finding an accuracy above 90% for morphological analysis and near 90% for orthographic conversion. This comprises the state of the art for Crimean Tatar morphological modelling, and, to our knowledge, is the first biscriptual single morphological transducer for any language

The electrochemical reduction of hydrogen sulfide on platinum in several room temperature ionic liquids

The electrochemical reduction of 1 atm hydrogen sulfide gas (H 2S) has been studied at a platinum microelectrode (10 μm diameter) in five room temperature ionic liquids (RTILs): [C2mim] [NTf 2], [C4mpyrr][NTf2], [C4mim][OTf], [C4mim][NO3], and [C4mim][PF6] (where [Cnmim]+ = 1-alkyl-3-methylimidazolium, [NTf 2]- = bis(trifluoromethylsulfonyl)imide, [C 4mpyrr]+ = N-butyl- N-methylpyrrolidinium, [OTf] - = trifluoromethlysulfonate, [NO3]- =nitrate, and [PF6]- = hexafluorophosphate). In all five RTILs, a chemically irreversible reduction peak was observed on the reductive sweep, followed by one or two oxidative peaks on the reverse scan. The oxidation peaks were assigned to the oxidation of SH- and adsorbed hydrogen. In addition, a small reductive peak was observed prior to the large wave in [C 2mim] [NTf2] only, which may be due to the reduction of a sulfur impurity in the gas. Potential-step chronoamperometry was carried out on the reduction peak of H2S, revealing diffusion coefficients of 3.2, 4.6, 2.4, 2.7, and 3.1 × 10-10 m2 s-1 and solubilities of 529, 236, 537, 438, and 230 mM in [C2mim][NTf 2], [C4mpyrr][NTf2], [C4mim][OTf], [C4mim][NO3], and [C4mim][PF6], respectively. The solubilities of H2S in RTILs are much higher than those reported in conventional molecular solvents, suggesting that RTILs may be very favorable gas sensing media for H2S detection. © 2008 American Chemical Society