A robust three-dimensional sandwich-like Co3S4 porous nanosheet/graphene sheet composite exhibits improved rate performance and cycling stability for both lithium and sodium storage.

Sodium-ion batteries have recently attracted considerable attention as a promising alternative to lithium-ion batteries owing to the natural abundance and low cost of sodium compared with lithium. Among all proposed anode materials for sodium-ion batteries, antimony is a desirable candidate due to its high theoretical capacity (660 mA h g–1). Herein, an antimony/multilayer graphene hybrid, in which antimony is homogeneously anchored on multilayer graphene, is produced by a confined vapor deposition method. The chemical bonding can realize robust and intimate contact between antimony and multilayer graphene, and the uniform distribution of antimony and the highly conductive and flexible multilayer graphene can not only improve sodium ion diffusion and electronic transport but also stabilize the solid electrolyte interphase upon the large volume changes of antimony during cycling. Consequently, the antimony/multilayer graphene hybrid shows a high reversible sodium storage capacity (452 mA h g–1 at a current density of 100 mA g–1), stable long-term cycling performance with 90% capacity retention after 200 cycles, and excellent rate capability (210 mA h g–1 under 5000 mA g–1). This facile synthesis approach and unique nanostructure can potentially be extended to other alloy materials for sodium-ion batteries.

Exposure to antibiotics during pregnancy can pose a systematic effect on human health. A few biomonitoring studies have demonstrated an extensive exposure of children to antibiotics, but there is still a lack of data for pregnant women. To assess the exposure of pregnant women to antibiotics and potential health risk, we investigated 536 pregnant women aged 16-42 years from two geographically different study sites in Eastern China in 2015. We measured 21 antibiotics of five categories (seven fluoroquinolones, three phenicols, four tetracyclines, three macrolides, and four sulfonamides) in urine using the isotope dilution ultraperformance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. The hazard index (HI) was calculated on the basis of estimated daily exposure dose and acceptable daily intakes. A total of 16 antibiotics were found in urine, with detection frequencies between 0.2 and 16.0%. Antibiotics were overall detected in 41.6% of urine, and two or more antibiotics were detected in 13.1% of urine. Ciprofloxacin, ofloxacin, and trimethoprim were most frequently detected in urine, with detection frequencies between 10 and 20%. The majority of the antibiotics tested had an estimated daily exposure dose less than 1 μg/kg/day, and 4.3% of pregnant women had a HI value of more than 1. These findings indicated that pregnant women were frequently exposed to antibiotics and some individuals were in the potential risk of adverse microbiological effects induced by antibiotics.

Silicon-based lithium-ion battery anodes have brought encouraging results to the current state-of-the-art battery technologies due to their high theoretical capacity, but their large-scale application has been hampered by a large volume change (>300%) of silicon upon lithium insertion and extraction, which leads to severe electrode pulverization and capacity degradation. Polymeric surfactants directing the combination of silicon nanoparticles and reduced graphene oxide have attracted great interest as promising choices for accommodating the huge volume variation of silicon. However, the influence of different polymeric surfactants on improving the electrochemical performance of silicon/reduced graphene oxide (Si/RGO) anodes remains unclear because of the different structural configurations of polymeric surfactants. Here, we systematically study the effect of different polymeric surfactants on enhancing the Si/RGO anode performance. Three of the most well-known polymeric surfactants, poly(sodium 4-styrenesulfonate) (PSS), poly(diallydimethylammonium chloride) (PDDA), and polyvinylpyrrolidone (PVP), were used to direct the combination of silicon nanoparticles and RGO through van der Waals interaction. The Si/RGO anodes made from these composites act as ideal models to investigate and compare how the van der Waals forces between polymeric surfactants and GO affect the final silicon anode performance from both experimental observations and theoretical simulations. We found that the capability of these three surfactants in enhancing long-term cycling stability and high-rate performance of the Si/RGO anodes decreased in the order of PVP > PDDA > PSS.

Raman spectra of a series of MgO-doped congruent LiNbO, crystals were obtained with MgO concentrations up to 30 mole%. Single crystals were successfully grown and no precipitates were discovered. The intensity, frequency and line width of the Raman phonons were studied as a function of doping percentage. An abrupt change was observed near the composition of 7.5 mol.% of MgO-doped LiNbO, crystal. From the spectral changes it is proposed that Mg2+ replaces the mis-sited NbS+ cation at Li sites first. When these mis-sited Nbs+ cations have been completely replaced, the Mg" cation then replaces the Li+ cation and creates vacancies at Li+ sites

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ZnO-doped lithium niobate crystals with a doped concentration of up to 8.3mol% were grown by the Czochralski technique. The effects of incorporating Zn2+ ions into LiNbO3 crystals were studied by powder x-ray diffraction and taking polarization hysteresis loop measurements. When the Li-site vacancy model is adopted, the coercive fields obtained from the polarization reversal measurement depend strongly on the number of NbLi4−+4VLi−. However, the coercive field of Zn-doped ions into LiNbO3 is insensitive to the ZnLi2++VLi−. Experimental results indicate that four distinct substitutions of Zn−2 ions incorporated into ions into LiNbO3 crystals for doping concentrations from 0to8.3mol%. The extent of Zn substitution is quantitatively determined for doping of below 7.5mol%.

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