Assessment of the induced effect of selected iron hydroxysulfates biosynthesized using Acidithiobacillus ferrooxidans for biomineralization of acid mine drainage.

Soluble iron and sulfate in acid mine drainage (AMD) can be greatly removed through the formation of minerals facilitated by seed crystals. However, the difference in the effects of jarosite and schwertmannite as endogenous seed crystals to induce AMD mineralization remains unclear. This paper intends to study the effect of Fe2+ oxidation and Fe3+ mineralization in the biosynthesis of minerals using different addition amounts and methods of jarosite or schwertmannite. The results showed that the addition amount and method of different seed crystals had no effect on the Fe2+ bio-oxidation but would change the Fe3+ mineralization efficiency. With the same amount of seed crystals added, jarosite exhibited a higher capacity to promote Fe3+ mineralization than schwertmannite. Adding seed crystals before the initiation of Fe2+ oxidation (0 h) could significantly promote Fe3+ mineralization efficiency. With the increase of seed crystals, jarosite could not only shorten the time required for mineral synthesis but also improve the final mineral yield, whereas schwertmannite could only shorten the time required for mineral synthesis. When Fe2+ was completely oxidized to Fe3+ (48 h), the supplementary of jarosite could still effectively improve Fe3+ mineralization efficiency, but the addition of schwertmannite no longer affected the final mineralization degree.

H3K4me3 as a target of di(2-ethylhexyl) phthalate (DEHP) impairing primordial follicle assembly.

Di (2-ethylhexyl) phthalate (DEHP) is a widely used plastics additive that growing evidence indicates as endocrine disruptor able to negatively affect various reproductive processes both in female and male animals, including humans. However, the precise molecular mechanism of such actions is not completely understood. In the present study, scRNA-seq was performed on the ovaries of offspring from mothers exposed to DEHP from 16.5 days post coitum to 3 days post-partum, when the primordial follicle (PF) stockpile is established. While the histological observations of the offspring ovaries from DEHP exposed mothers confirmed previous data about a distinct reduction of oocytes enclosed in PFs. Focusing on oocytes, scRNA-seq analyses showed that the genes that mostly changed by DEHP were enriched GO terms related to histone H3-K4 methylation. Moreover, we observed H3K4me3 level, an epigenetics modification of H3 that is crucial for chromatin transcription, decreased by 40.28% (P < 0.01) in DEHP-treated group compared with control. When the newborn ovaries were cultured in vitro, the DEHP effects were abolished by tamoxifen (an estrogen receptor antagonist) or overexpression of Smyd3 (one specific methyltransferase of H3K4me3), in particular, the percentage of oocyte enclosed in PF was increased by 15.39% in DEHP plus Smyd3 overexpression group than of DEHP group (P < 0.01), which was accompanied by the upregulation of H3K4me3. Collectively, the present results discover Smyd3-H3K4me3 as a novel target of the deleterious ER-mediated effect of DEHP on PF formation during early folliculogenesis in the mouse and highlight epigenetics changes as prominent targets of endocrine disruptors like DEHP.

Investigation into the electrochemical behaviour of silver in alkaline solution and the influence of Au-decoration using operando Raman spectroscopy.

To explore the basic chemistry in the electrochemical environment, the electrochemical behavior of Ag and the influence of Au decoration is investigated with cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and operando Raman measurements in a 1 M KOH solution. During the anodic CV sweep, Ag is oxidized to Ag2O in the first step through a one-electron process, and then, AgO in the second step through another one-electron process. Meanwhile, some AgO is formed at a relatively low potential under the irradiation of visible lights (photoelectrochemical oxidation). In the GCD mode, it is found that apart from the two one-electron processes, part of the Ag is oxidized to AgO directly through a two-electron process in the second oxidation step, implying slightly different activities of these reactions in the CV and GCD mode. During cathodic CV sweep and galvanostatic discharge, opposite reactions take place respectively. The coulombic efficiency is calculated to be only ∼82% from the CV cycle at 5 mV s-1 due to the formation of silver hydroxyl species (oxidation state) in a low potential range. For the Au decorated Ag, Raman signals from these species disappeared and the coulombic efficiency is enhanced to 95%, indicating an obvious improvement in reversibility.

A promising water-in-salt electrolyte for aqueous based electrochemical energy storage cells with a wide potential window: highly concentrated HCOOK.

Recently, water-in-salt electrolytes have been widely reported because of their ability in broadening the potential window of aqueous based energy storage devices. Herein, another eco-friendly and cost-effective electrolyte, concentrated potassium formate of 40 M HCOOK where the water-to-salt molar ratio falls to 1.38 : 1, is proposed. The electrolyte demonstrates a wide potential window of up to 4 V (-2.5 to 1.5 V vs. Ag/AgCl) with a glassy carbon electrode. Compared with a CH3COOK based electrolyte, the HCOOK possesses lower stable negative potential and higher ionic conductivity. For an activated carbon based supecapacitive electrode, a low discharge potential of -2.4 V vs. Ag/AgCl can be achieved. Besides, a high capacity of 321 F g-1 is obtained at 5 A g-1 and it is still as high as 121 F g-1 at 20 A g-1. Meanwhile, typical K-battery behavior is exhibited for the KTi2(PO4)3 anode and a reversible capacity of 15 mA h g-1 can be delivered at 0.1 A g-1.

Fast Energy Storage in Two-Dimensional MoO2 Enabled by Uniform Oriented Tunnels.

While pseudocapacitive electrodes have potential to store more energy than electrical double-layer capacitive electrodes, their rate capability is often limited by the sluggish kinetics of the Faradaic reactions or poor electronic and ionic conductivity. Unlike most transition-metal oxides, MoO2 is a very promising material for fast energy storage, attributed to its unusually high electronic and ionic conductivity; the one-dimensional tunnel is ideally suited for fast ionic transport. Here we report our findings in preparation and characterization of ultrathin MoO2 sheets with oriented tunnels as a pseudocapacitive electrode for fast charge storage/release. A composite electrode consisting of MoO2 and 5 wt % GO demonstrates a capacity of 1097 C g-1 at 2 mV s-1 and 390 C g-1 at 1000 mV s-1 while maintaining ∼80% of the initial capacity after 10,000 cycles at 50 mV s-1, due to minimal change in structural features of the MoO2 during charge/discharge, except a small volume change (∼14%), as revealed from operando Raman spectroscopy, X-ray analyses, and density functional theory calculations. Further, the volume change during cycling is highly reversible, implying high structural stability and long cycling life.

Investigation into the energy storage behaviour of layered α-V2O5 as a pseudo-capacitive electrode using operando Raman spectroscopy and a quartz crystal microbalance.

α-V2O5 nanowires with a layered structure have been fabricated through a two-step procedure. When measured as a pseudo-capacitive electrode with a three-electrode configuration in 1 M Na2SO4 aqueous solutions, α-V2O5 exhibits ideal capacitive characteristics with a specific capacitance of ∼238 F g-1 at a high current of 2 A g-1, but poor cycling stability with a continuous drop in the first 2000 cycles before it is maintained. To find possible solutions towards this problem, the energy storage behavior of the α-V2O5 electrode has been carefully investigated. In situ Raman analysis suggests that it is electrolytic hydrated cations [Na(H2O)n]+ rather than anions (SO42-) that are involved in the energy storage process through reversible adsorption/desorption on the surface or intercalation/deintercalation at the interlayer of the (001) planes accompanied by interlayer spacing expansion/contraction. Moreover, the electrochemical quartz crystal microbalance results indicate that, besides a reversible mass change, there is a continuous mass loss that may originate from slow dissolution of V2O5, which should bear the main responsibility for the poor stability (initial dramatic drop). Hence, how to inhibit dissolution, such as by coating or adding additives in the electrolyte, is found to be the key approach to improve the stability of V2O5 based electrodes.

Porous Functionalized Self-Standing Carbon Fiber Paper Electrodes for High-Performance Capacitive Energy Storage.

A facile and cost-efficient approach to functionalize raw carbon fiber paper (CFP) used for a self-standing capacitive electrode has been proposed here. Benefiting from the improved specific surface area and surface functional groups, the functionalized CFP (F-CFP) showed much enhanced capacitive performance, 3 orders of magnitude higher than that of the raw CFP. It delivered the areal capacitance of 1275 mF cm-2 at 5 mA cm-2 with a rather wide voltage window of 1.4 V (-0.4 to 1 V vs Ag/AgCl) in 0.5 M H2SO4. However, in a neutral 1 M Na2SO4 aqueous solution, although the areal capacitance of 1115 mF cm-2 at 3 mA cm-2 is slightly smaller, the potential window is much wider (2 V, -1 to 1 V vs Ag/AgCl), indicating a high overpotential of hydrogen evolution. The areal capacitance was still as high as 722 mF cm-2 at a very fast charge-discharge current density of 50 mA cm-2, and about 66% of the initial capacitance (at 3 mA cm-2) was remained in Na2SO4, indicating considerable rate capability.