Responses of zebra and quagga mussels to copper and tribytiltin exposure: Bioconcentration, metabolic and cardiac biomarkers.

One of the top ecological priorities is to find sensitive indicators for pollution monitoring. This study focuses on the bioconcentration and responses (condition index, survival, oxygen consumption, heart rates, and oxidative stress and neurotoxic effect biomarkers) of mussels from the Volga River basin, Dreissena polymorpha and Dreissena bugensis, to long-term exposure to toxic chemicals such as tributyltin (TBT, 25 and 100 ng/L) and copper (Cu, 100 and 1000 µg/L). We found that TBT was present in the tissues of zebra and quagga mussels in comparable amounts, whereas the bioconcentration factor of Cu varied depending on its concentration in water. Differences in responses between the two species were revealed. When exposed to high Cu concentrations or a Cu-TBT mixture, quagga mussels had a lower survival rate and a longer heart rate recovery time than zebra mussels. TBT treatment caused neurotoxicity (decreased acetylcholinesterase activity) and oxidative stress (increased levels of thiobarbituric acid reactive substances) in both species. TBT and Cu levels in mussel tissues correlated positively with the condition index, but correlated with the level of acetylcholinesterase in the mussel gills. The principal component analysis revealed three main components: the first consists of linear combinations of 14 variables reflecting TBT water pollution, TBT and Cu levels in mussel tissues, and biochemical indicators; the second includes Cu water concentration, cardiac tolerance, and mussel size; and the third combines weight, metabolic rate, and heart rates. Quagga mussels are less tolerable to contaminants than zebra mussels, so they may be used as a sensitive indicator.

A High Yield Synthesis of an Octastannacubane and a Bis(silyl) Stannylene via Reductive Elimination of a Silane.

Thermolysis of tris(silyl) tin hydride 2 at 70 °C for 3 hours results in elimination of tBu2 MeSiH and generation of bis(silyl) stannylene 3 which dimerizes instantaneously yielding distannene 4. Compound 3 can be trapped by NHCMe yielding stannylene-NHCMe complex 5. Upon heating (70 °C, 24 h) 4 yields stannyl radical 8 along with pentastannatricyclo[2.1.0.02, 5 ]pentane 10 (ca. 30 %) and traces (ca. 5 %) of the novel octastannacubane 9. Remarkably, octastannacubane 9 is produced in 70 % yield by mild heating (50 °C) of 1,1,2,2-tetrasilyldistannane 11, along with tBu2 MeSiH. Octastannacubane 9 was characterized by X-ray crystallography, NMR and UV/Vis spectroscopy. Based on DFT quantum-mechanical calculations the 11 → 9 transformation occurs via reductive elimination of two tBu2 MeSiH molecules from 11 yielding a distannyne, (or its bis-stannylene isomer), followed by its tetramerization.

Protection of Poly(Vinyl Chloride) Films against Photodegradation Using Various Valsartan Tin Complexes.

Poly(vinyl chloride) is a common plastic that is widely used in many industrial applications. Poly(vinyl chloride) is mixed with additives to improve its mechanical and physical properties and to enable its use in harsh environments. Herein, to protect poly(vinyl chloride) films against photoirradiation with ultraviolet light, a number of tin complexes containing valsartan were synthesized and their chemical structures were established. Fourier-transform infrared spectroscopy, weight loss, and molecular weight determination showed that the non-desirable changes were lower in the films containing the tin complexes than for the blank polymeric films. Analysis of the surface morphology of the irradiated polymeric materials showed that the films containing additives were less rough than the irradiated blank film. The tin complexes protected the poly(vinyl chloride) films against irradiation, where the complexes with high aromaticity were particularly effective. The additives act as primary and secondary stabilizers that absorb the incident radiation and slowly remit it to the polymeric chain as heat energy over time at a harmless level.

Spectroscopic and thermal properties of stannadithiane compounds bearing endocyclic ether and lactone groups.

Four related stannadithiane compounds containing different endocyclic functional groups -including ether (1), diether (2), lactone (3), and spirolactone (4)- were prepared. The conformational landscape has been fully determined for the 8-membered representative (compound 1) resulting in a distorted crown form with the butyl chains adopting an extended conformation. The infrared and Raman spectra of stannadithiane species have been measured and interpreted, aided by quantum chemical calculations and potential energy surface analysis. Special attention has been devoted to the analysis of the vibrational features of the heterocyclic moieties. The characteristic νas(SnS) and νs(SnS) stretching modes of the SnS2endo-cyclic group were clearly observed in the Raman spectra at around 340 and 315 cm-1, respectively. The exo-cyclic ν(SnC) stretching modes were found near 590 and 565 cm-1 for the antisymmetric and symmetric motions, respectively. Thermal behavior for compounds 2-4 has been determined by thermogravimetric methods.

Understanding the Lithiation of the Sn Anode for High-Performance Li-Ion Batteries with Exploration of Novel Li-Sn Compounds at Ambient and Moderately High Pressure.

Volume expansion and elastic softening of the Sn anode on lithiation result in mechanical degradation and pulverization of Sn, affecting the overall performance of Li-Sn batteries. It can, however, be overcome with the help of void space engineering by using a LixSn phase as the prelithiated anode, where an optimal value for x is desired. Currently, Li4.25Sn is known as the most lithiated Li-Sn compound, but recent studies have shown that at high pressure, several exotic and unusual stoichiometries can be obtained that may even survive decompression from high-to-ambient pressure with improved mechanical properties. With a belief that hydrostatic pressure may help in realizing Li-richer (x > 4.25) Li-Sn compounds as well, we performed extensive calculations using an evolutionary algorithm and density functional theory to explore all stable and low-energy metastable Li-Sn compositions at pressures ranging from 1 atm to 20 GPa. This not only helped us in enriching the chemistry of a Li-Sn system, in general, but also in improving our understanding of the reaction mechanism in Li-Sn batteries, in particular, and guiding a route to improve the performance of Li-ion batteries through synthesis of Li-rich phases. Besides the experimentally known Li-Sn compounds, our study reveals the existence of five unreported stoichiometries (Li8Sn3, Li3Sn1, Li4Sn1, Li5Sn1, and Li7Sn1) and their associated crystal structures at ambient and high pressure. Although Li8Sn3 has been identified as one of the most stable Li-Sn compound in the entire pressure range (1 atm-20 GPa) with R3̅m symmetry, the Li-rich compounds like Li3Sn1-P2/m, Li4Sn1-R3̅m, Li5Sn1-C2/m, and Li7Sn1-C2/m are predicted to be metastable at ambient pressure and found to get thermodynamically stable at high pressure. Here, the discovery of Li5Sn1 and Li7Sn1 opens up the possibility to integrate them as a prelithiated anode for efficiently preventing electrochemical pulverization, as compared to the experimentally known highest lithiated compound, Li17Sn4.

Development and Characterization of a Human Reporter Cell Line for the Assessment of Thyroid Receptor Transcriptional Activity: A Case of Organotin Endocrine Disruptors.

We developed and characterized the human luciferase reporter cell line PZ-TR for the assessment of thyroid receptor (TR) transcriptional activity. Triiodothyronine (T3) induced luciferase activity in a dose-dependent manner, and the sensitivity of assay allowed for the detection of nanomolar T3 concentrations. The luciferase activity was induced by a maximum of (2.42 ± 0.14)-(2.73 ± 0.23)-fold after 24 h of exposure to 10 nM T3. We did not observe a nonspecific induction of luciferase activity by other steroid hormones and VDR ligands, with the exception of partial activation by retinoic acids. Cryopreservation of PZ-TR cells did not influence their functionality, responsivity to T3, or cell morphology, even after long-term cultivation. PZ-TR cells were used to evaluate the effects of organic tin compounds on TR. We found that the tributyltin and triphenyltin derivatives induced luciferase activity and that application of organotins in combination with T3 enhanced the effect of T3. These findings indicate that organic tin compounds have potential to interfere with TR-mediated regulation of gene expression and influence the physiological activity of thyroid hormones.