China has become one of the major recycling sites for the electronic waste (e-waste) from worldwide. Pollutants emerged from the e-waste dismantling and the subsequent health effects to populations are of great concern. Typically, exposure to organic pollutants, such as bisphenol A (BPA) especially generated from primitive dismantling, is an important scientific issue for their adverse health effects to local residents. In this study, 29 e-waste dismantling workers and 24 local residents from a dismantling area in North China were recruited as the exposure group. Residents (N = 53) living 40 km away from this e-waste area were selected as the reference. The median concentration of urinary BPA of the exposure group was 10.7 mu g.g(-1) creatinine, which was significantly higher than that of the references (0.66 mu g.g(-1) creatinine; P < 0.01), indicating that working and/or living in the e-waste area caused the elevated body burden of BPA. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) of the exposure group (median: 236 mu g.g(-1) creatinine) was higher than that of the references (median: 142 mu g.g(-1) creatinine) with a marginal significance (P = 0.055). Meanwhile, serum levels of glutathione S-transferase (GSH-ST) and Cu/Zn-Superoxide dismutase (Cu/Zn-SOD) were significantly lower in the exposure group, while glutathione peroxidase (GSHPx) was higher when compared to the references (P < 0.01). Significantly positive association between urinary BPA and 8-OHdG was found (P < 0.05); however, significantly negative association was found between BPA and serum GSH-ST (P < 0.01). After controlling for confounders, 34.9% (95% CI: 19.4%-52.3%) increment of urinary 8-OHdG and 5.46% (95% CI: 1.17%-9.56%) decrement of serum GSH-ST per one-fold increase of BPA were estimated. Those results provided evidence on high exposure level of BPA among the populations from the e-waste dismantling area and a high risk of oxidative damage to DNA.
Electrons can be transferred from microorganisms to multivalent metal ions that are associated with minerals and vice versa. As the microbial cell envelope is neither physically permeable to minerals nor electrically conductive, microorganisms have evolved strategies to exchange electrons with extracellular minerals. In this Review, we discuss the molecular mechanisms that underlie the ability of microorganisms to exchange electrons, such as c-type cytochromes and microbial nanowires, with extracellular minerals and with microorganisms of the same or different species. Microorganisms that have extracellular electron transfer capability can be used for biotechnological applications, including bioremediation, biomining and the production of biofuels and nanomaterials.
More trading is algorithmic or computer generated, and in markets where it is allowed, high&nbsp;frequency. However, what happens when there is an algorithmic trading error? This study&nbsp;attempts to answer that question by examining the August 16, 2013, fat-finger trade in Chinese&nbsp;equity and equity futures markets. We find that both markets were excessively volatile, illiquid,&nbsp;and positively skewed. Moreover, we document that index returns are predictable for a shorttime, indicating that the fat-finger event induced an inefficient market. Our results highlight&nbsp;the importance of market surveillance and regulation to lessen the damage of future fat-finger&nbsp;events.
Ultrasmooth perovskite thin films are prepared by a solution-based one-step micro-flowing anti-solvent deposition (MAD) method carried out in air with simplicity and practicability. Engaging inert gas blow and anti-solvent drips as accelerators, ultrafast crystallizing, thickness controllable, and high quality methylammonium lead iodide films are prepared with a least root mean square roughness of 1.43 nm (1.95 nm on average), achieving the smoothest surface morphology to the best of our knowledge, as well as a rather compact perovskite layer with a high coverage ratio. Perovskite films formed from MAD require no annealing procedure to ultimately crystallize, realizing a very fast crystallizing procedure within few seconds. By controlling the thickness of perovskite films, superior photovoltaic performance of solar cells with a large fill factor of 0.8 and a PCE of 15.98% is achieved without a glovebox. MAD technology will benefit not only highly efficient photovoltaic devices, but also perovskite-based hybrid optoelectronic devices with field effect transistors and light emitting diodes as well.
In this letter, a plasma-free etch stop structure is developed for GaN HEMT toward enhancement-mode operation. The self-terminated precision gate recess is realized by inserting a thin AlN/GaN bilayer in the AlGaN barrier layer. The gate recess is stopped automatically at the GaN insertion layer after high-temperature oxidation and wet etch, leaving a thin AlGaN barrier to maintain a quantum well channel that is normally pinched off. With addition of an Al2O3 gate dielectric, quasi normally OFF GaN MOSHEMTs have been fabricated with high threshold uniformity and low ON-resistance comparable with the normally ON devices on the same wafer. A high channel mobility of 1400 cm(2)/V . s was obtained due to the preservation of the high electron mobility in the quantum-well channel under the gate.
