•Currently, Bt crops have been widely commercialized for cultivation in the world.•The effects of Bt toxin on soil sorption of heavy metals has not been reported.•Sorption of Pb (II) by red and black ...soils decreased in the presence of the Bt toxin.•The environmental risk of Pb (II) may increase if toxin is released by Bt crops.
Bt crops have been widely commercialized for cultivation in the world, but as yet, the effects of Bt toxin on sorption of heavy metals in soils has not been reported. In this study, the effects of toxin from Bacillus thuringiensis on Pb (II) sorption by red (Ultisol) and black soil (Vertisol) were studied using the batch method. The results showed that Pb(II) sorption by both soil types decreased in the presence of Bt toxin from 0 to 10 mg/L, which was probably due to the sorptive sites competition and Pb–toxin complex formation. The Langmuir and Freundlich isotherm models were fitted well to the sorption data at different Bt toxin additions. The sorption capacity of black soil for Pb (II) was higher than that of red soil, however, the influential trends of Bt toxin to the maximum capacity of Pb (II) in both soils was reversed. Sorption of Pb (II) in both soils was rapid and reached equilibrium within 80 min, following the pseudo-second-order kinetic model. Decreasing sorption of Pb (II) by red and black soils was observed in the presence of Bt toxin, suggesting that the environmental risk of Pb(II) may increase if Bt toxin is released by Bt crops.
The Cu 2 ZnSn(S,Se) 4 (CZTSSe) material is considered a promising semiconductor material for commercial photovoltaic applications due to its high theoretical efficiency, high absorption coefficient, ...tunable direct bandgap, high element abundance, and low production cost. However, the efficiency of solution-processed CZTSSe thin-film solar cells still falls short of their theoretical efficiency limit (∼31.0%) and that of their predecessor copper indium gallium selenide (CIGS) cells. The relatively low device efficiency is mainly due to bulk and interface defects generated during the preparation of the absorber layer. For achieving a high-quality CZTSSe absorber layer via solution processing, the properties of the solvent are essential. To further improve the efficiency of CZTSSe cells prepared by solution methods, this review provides a detailed summary of the current research status on the selection of solvents and solutes or precursor materials, regulation of bulk and interface defects, optimization of various functional layers, and design of device structures in the preparation of high-efficiency CZTSSe by six solution methods based on different solvent systems (hydrazine, 1,2-ethylenediamine and 1,2-ethanedithiol, dimethyl sulfoxide, N , N -dimethylformamide, 2-methoxyethanol, and thioglycolic acid–ammonia systems). Finally, this article discusses new insights and perspectives for achieving high-efficiency CZTSSe thin-film solar cells.
This paper focuses on the flocculability of simulated wastewater containing heavy metal ions (Fe
3+
, Cd
2+
) or phosphorus by zeolite, microbial flocculants (MBF) produced by
Aspergillus niger
and ...the composite flocculant composed of zeolite and MBF. The main results are presented as follows: zeolite was a good flocculant when the contamination of the three simulated wastewaters was low, but the treated water is of turbidness and the particles in it are hard to precipitate. The MBF have a good flocculability toward Fe
3+
wastewater, as well as particulate matter. Significant changes in flocculability occurred after adding the composite flocculant in different simulated wastewaters, the best or least effect respective for Fe
3+
and Cd
2+
wastewater. The research we have done shows that the method by which the composite flocculant is used to treat the wastewater containing heavy metal ions or phosphorus provides important reference value for practical application.
•These SiHfCB precursors are characterised by a high Hf content (no precipitation), uniform dispersion, excellent flowability and SiHfCB precursor (Hf/Si=0.2) high ceramic yield at 1500 °C.•The ...pyrolysis products of the precursors were HfB2-SiC nanopowders with uniform particle sizes (40–60 nm). Using these nanopowders (Hf/Si=0.2), a light weight bulk HfB2-SiC composites were prepared by hot-press sintering process with a density of 5.23 g cm−3, which is significantly lower compared to other hafnium-based high temperature ceramics.•HfB2-SiC composites exhibit excellent non-ablative properties in an oxygen-rich ultrahigh temperature environment of 2500 °C with a linear ablation rate of only 2.5 × 10−4 mm s−1.•The formation of HfO2 and HfO2-SiO2 glass layers contributes to the reduction of the linear ablation rate and effectively inhibits ablation under the intense conditions of an oxygen-acetylene torch at 2500 °C.
The current generation of ultrahigh temperature ceramic precursors typically encounters obstacles in achieving high ceramic yields (<40 wt.%) due to the challenges in integrating significant amounts of boron, which hampers their conversion into boride-based ultrahigh temperature ceramics. To tackle these challenges, a serious of pioneering liquid multi-component hafnium-containing ceramic SiHfCB precursors (with different Hf/Si ratios) have been developed. These novel precursors are featured with stable molecular structure and high ceramic yield which were successfully created through a novel one-pot polymerization process. They present in liquid form and their structure is characterized by C-C bonds forming its main chain with branched chains of O-Si-O, Si-O-Hf, Si-O-B, and B-O-Hf which have untapped advantages including uniform component dispersion, and excellent fluidity. The ceramic yield of SiHfCB precursor with Hf/Si of 0.2 is remarkably up to 68.6 wt.% at 1500 °C, and their Hf content exceeded 50 wt.%. Of particular interest, the pyrolyzed product HfB2-SiC nanopowders derived from the SiHfCB precursor with Hf/Si of 0.2, consist of nanopowders in the 40–60 nm range with a density of 5.23 g cm−3. Remarkably, this material demonstrates exceptional performance in ultrahigh temperature oxygen-containing environments at 2500 °C, showing near-zero ablation with a linear ablation rate of just 2.5 × 10−4 mm s−1. Post-ablation analysis of the microstructure reveals that the formation of a lava-like HfO2 and HfO2-SiO2 oxide layer effectively blocks oxygen penetration and provides excellent oxidation resistance. The innovative SiHfCB hafnium-containing ceramic precursor offers a groundbreaking solution for the preparation of lightweight ultrahigh-temperature ceramics. This development is poised to provide robust technical support for the use of ultrahigh temperature ceramics in non-ablative thermal protective systems, particularly in the construction of hypersonic vehicles, where ultrahigh temperature resilience is crucial.
Illustration of the liquid SiHfCB precursor preparation process and schematic diagram of ablation mechanisms of HfB2-SiC composites
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To investigate the influence of cyanobacterial blooms on phosphorus release across the sediment-water interface and the repair mechanisms of internal phosphorus by harvesting of cyanobacteria, a ...series of laboratory-based experiments were conducted. Microcystis aeruginosa was cultured in phosphorus-free BG11 medium containing sediments from different eutrophic water bodies. The culture solution was removed and the same volume of phosphorus-free BG11 medium was put into the system until the M. aeruginosa had died. Cyanobacterial density, pH and different phosphorus forms in culture solution and sediments after culturing M. aeruginosa were determined. The results showed that cyanobacterial blooms stimulated phosphorus release from the sediment to the overlying water for the sediment in the eutrophic water body. Phosphorus released from the sediment was assimilated by M. aeruginosa and no increase in water-soluble phosphorus was observed. Cyanobacterial blooms caused sharp increases in different phosphorus fractions of sediment with the exception of the phosphorite-type (Ca ₁₀-P). Cyanobacterial blooms decomposed iron minerals in the sediment yet there was no clear evidence to demonstrate a positive correlation between water-soluble phosphorus in the overlying water and iron bound phosphorus (Fe-P) in the sediment. These results indicated that harvesting of cyanobacteria might be a suitable method to eradicate cyanobacterial blooms and to limit phosphorus pollution under controlled external nutrient loads.
Despite the significant improvement on spatial resolution, NanoSIMS still preserves relatively high mass resolution, sensitivity, and analytical precision. It has become an important analytical ...platform to determine chemical compositions of solid materials, and has been widely used in space, earth, life, and materials sciences, etc. By using a Cs＋ ion beam with a size as small as 50 nm scanning over sample surfaces, we are able to obtain high spatial resolution images of up to 7 species simultaneously. When utilizing Faraday cup, high analytical precision of 0.3‰-0.5‰ （1SD） for C, O and S isotopic analysis can be achieved. Although this precision level is still lower than that of conventional SIMS, it already meets the major requirements of Earth Sciences. In 2011, the first NanoSIMS of China （Cameca NanoSIMS 50L） was installed at Institute of Geology and Geophysics, Chinese Academy of Sciences. Based on the working mechanism and analytical modes of the instrument, this paper will systematically introduce the analytical methods established with the NanoSIMS and their potential applications in earth sciences. These methods include trace element distribution images in mineral zoning, high spatial resolution （2-5/am） Pb-Pb and U-Pb dating, water content and H isotopic analysis for silicate glass and apatite, C isotopic analysis for diamond and graphite, O isotopic analysis for carbonate, S isotopic analysis for sulfides. In addition, the specific requirements for sample preparation will also be introduced in order to facilitate domestic earth scientists＇ use.
Molecular mechanisms and gene regulation are of interest in the area of geomicrobiology in which the interaction between microbes and minerals is studied. This paper focuses on the regulation of the ...expression of carbonic anhydrase (CA) genes in Bacillus mucilaginosus and the effects of the expression product of the B. mucilaginosus CA gene in Escherichia coli on calcite weathering. Real-time fluorescent quantitative PCR (RT-qPCR) was used to explore the relationship between CA gene expression in B. mucilaginosus and promotion of calcite dissolution under condition of Ca
2+
deficiency. The results showed that adding calcite to the medium, which lacks Ca
2+
, can up-regulate the expression of the bacterial CA genes to accelerate calcite dissolution for bacterial growth. CA genes from B. mucilaginosus were transferred into E. coli by cloning. We then employed crude enzyme extract from the resultant E. coli strain in calcite dissolution experiments. The enzyme extract promoted calcite dissolution. These findings provide direct evidence for the role of microbial CA on mineral weathering and mineral nutrition release.
Photovoltaic (PV) technology provides a sustainable solution to meet the increasing energy demands from society. Silver sulfide (Ag
2
S), a direct bandgap PV material, is considered a promising ...semiconductor due to its excellent optical and electrical properties, including high theoretical efficiency (∼30%), tunable bandgap (
E
g
= 0.9-1.1 eV), high thermodynamic stability, low toxicity, abundant elemental availability, and low fabrication cost. Despite efforts to improve the photovoltaic conversion efficiency of Ag
2
S devices through various approaches such as film deposition techniques, device structures, and interface optimization, the quality of the absorber layer, structural defects, and non-ideal charge separation at the interfaces remain obstacles for further performance enhancement. Therefore, it is crucial to gain a deeper understanding of the fabrication methods, optoelectronic properties, and efficiency loss mechanisms of Ag
2
S solar cells to achieve rapid advancements in device performance. This review summarizes the current research status on the fabrication methods, device structure selection, design, and optimization of Ag
2
S thin films. Finally, insights into achieving high-efficiency Ag
2
S devices by improving the crystallinity of the absorber layer and reducing interface defects are discussed.
This review summarizes the current research status on fabrication methods, device structure selection, design and optimization of Ag
2
S thin films. Insights into achieving high-efficiency Ag
2
S devices by improving the crystallinity of the absorber layer and reducing interface defects are discussed.
We report an imaging method of zircon U-Pb dating with NanoSIMS 50 L, which overcomes the significant U-Pb fractionation as the pit was sputtered deeper during conventional spot mode analysis and can ...be applied to irregular small grains or heterogeneous areas of zircon. The U-Pb and Pb-Pb ages can be acquired simultaneously for 2 μm×2 μm（for small grains） or 1 μm×9 μm（for zoned grains）, together with Zr, Y and other trace elements distributions. Using zircon M257 as standard, the U-Pb ages of other zircon standards, including Qinghu, Plesovice, Temora and 91500, were measured to（2σ） as158.8±0.8, 335.9±3.4, 412.0±12 and 1067±12 Ma, respectively, consistent with the recommended values within the analytical uncertainties. Tiny zircon grains in the impact melt breccia of the lunar meteorite SaU 169 were also measured in this study,with a Pb-Pb age of 3912±14 Ma and a U-Pb age of 3917±17 Ma, similar to previous results reported for the same meteorite.The imaging method was also applied to determine U-Pb age of the thin overgrowth rims of Longtan metamorphic zircon, with a Pb-Pb age of 1933±27 Ma and a U-Pb age of 1935±25 Ma, clearly distinct from the Pb-Pb age of 2098±61 Ma and the U-Pb age of 2054±40 Ma for detrital cores.
The Mt. Beigu wetland, which has undergone periodical changes in water level, lies by the Yangtze River, and its dominant plants are Phragmites communis, Phalaris arundinacea and Polygonum ...lapathifolium. In order to study the distribution characteristics of nitrogen and phosphorus in the ecological system of the Mt. Beigu wetland, the authors measured the contents of total nitrogen and total phosphorus in Phragmites communis, Phalaris arundinacea and Polygonum lapathifolium, and the contents of nitrogen and phosphorus in the wetland soils with different plant species. In addition the authors investigated the influence of various plants on the spatial and seasonal （spring/autumn） distributions of nitrogen and phosphorus in the wetland soil. The contents of nitrogen and phosphorus in Phalaris arundinacea are significantly higher than those of the other two plant species in the same part. Secondary pollution of phosphorus in the wetland results mainly from Phalaris arundinacea. Phragmites communis effectively carries away nitrogen and phosphorus in the wetland soil in the wet season. The capacity of Polygonum lapathifolium to remove nitrogen is lowest among the 3 species of plants. These findings offer a theoretical foundation for the selection of plant species to restore the ecological environment and for the selection of time and depth for purging silt on the riverside wetland.
