Distinct photochemistry of adsorbed and coprecipitated dicarboxylates with ferrihydrite: Implications for iron reductive dissolution and carbon stabilization.

Although ligand-promoted photodissolution of ferrihydrite (FH) has long been known for low molecular weight organic acids (LMWOAs), such as oxalate (Oxa) and malonate (Mal), photochemistry of coprecipitated FH with Oxa and Mal remains unknown, despite the importance of these mineral-organic associations in carbon retention has been acknowledged recently. In this study, ferrihydrite-LMWOAs associations (FLAs) were synthesized under circumneutral conditions. Photo-dissolution kinetics of FLAs were compared with those of adsorbed LMWOAs on FH surface and dissolved Fe-LMWOAs complexes through monitoring Fe(II) formation and organic carbon decay. For aqueous Fe(III)-LMWOAs complexes, Fe(II) yield was controlled by the initial concentration of LMWOAs and nature of photochemically generated carbon-centered radicals. Inner-sphere mononuclear bidentate (MB) configuration dominated while LMWOAs were adsorbed on the FH surface. MB complex of FH-Oxa was more photoreactive, leading to the rapid depletion of Oxa. Oxa can be readsorbed but in the form of binuclear bidentate and outer-sphere complexation, with much lower photoreactivity. While LMWOAs was coprecipitated with FH, the combination mode of LMWOAs with FH includes surface adsorption with a mononuclear bidentate structure and internal physical inclusion. Higher content of LMWOAs in the FLAs promoted the photo-production of Fe(II) as compared to pure FH, while it was not the case for FLAs containing moderate amounts of LMWOAs. The distinct photochemistry of adsorbed and coprecipitated Fe-LMWOAs complexes is attributed to ligand availability and configuration patterns of LMWOAs on the surface or entrapped in the interior structure. The present findings have significant implications for understanding the photochemical redox cycling of iron across the interface of Fe-organic mineral associates.

Phosphate-mediated degradation of organic pollutants in water with peroxymonosulfate revisited: Radical or non-radical oxidation?

Whilst it is generally recognized that phosphate enables to promote the removal of some organic pollutants with peroxymonosulfate (PMS) oxidation, however, there is an ongoing debate as to whether free radicals are involved. By integrating different methodologies, here we provide new insights into the reaction mechanism of the binary mixture of phosphates (i.e., NaH2PO4, Na2HPO3, and NaH2PO2) with peroxymonosulfate (PMS) or hydrogen peroxide (H2O2). Enhanced degradation of organic pollutants and observation of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) adducts (i.e. DMPOOH and 5,5-dimethyl-2-oxopyrroline-1-oxyl (DMPOX)) with electron paramagnetic resonance (EPR) in most phosphates/PMS system seemly support a radical-dominant mechanism. However, fluorescence probe experiments confirm that no significant amount of hydroxyl radicals (•OH) are produced in such reaction systems. PMS in the phosphate solutions (without any organics) remains relatively stable, but is only consumed while organic substrates are present, which is distinct from a typical radical-dominant Co2+/PMS system where PMS is continuously decomposed. Through density functional theory (DFT) calculation, the energy barriers of the phosphates/PMS reaction processes are greatly decreased when non-radical mechanism dominates. Complementary evidence suggests that the reactive intermediates of PMS-phosphate complex, rather than the free radicals, are capable of oxidizing electron-rich substrates such as DMPO and organic pollutants. Taking the case of phosphate/PMS system as an example, this study demonstrates the necessity of acquisition of lines of evidence for resolving paradoxes in identifying EPR adducts.

Vapor-phase biodegradation and natural attenuation of petroleum VOCs in the unsaturated zone: A microcosm study.

Traditional natural attenuation studies focus on aqueous process in the saturated zone while vapor-phase biodegradation and natural attenuation in the unsaturated zone received much less attention. This study used microcosm experiments to explore the vapor-phase biodegradation and natural attenuation of 23 petroleum VOCs in the unsaturated zone including 7 monoaromatic hydrocarbons, 6 n-alkanes, 4 cycloalkanes, 3 alkylcycloalkanes and 3 fuel ethers. We found that monoaromatic hydrocarbon vapors were easily attenuated with significantly high first-order attenuation rates (9.48 d-1-43.20 d-1) in live yellow earth, of which toluene and benzene had the highest rates (43.20 d-1 and 28.32 d-1, respectively). The 13 aliphatic hydrocarbons and 3 fuel ethers all have relatively low attenuation rates (<0.54 d-1) in live soil and negligible biodegradation contribution. We explored the effects of soil types (black soil, yellow earth, lateritic red earth and quartz sand), soil moisture (2, 5, 10, and 17 wt%) contents and temperatures (4, 15, 25, 35 and 45 °C) on the vapor attenuation. Results showed that increasing soil organic matter (SOM) content, silt content, porosity and soil microorganism numbers enhanced contaminant attenuation and remediation efficiency. Increasing moisture content reduced the apparent first-order biodegradation rates of monoaromatic hydrocarbon vapors. The vapor-phase biodegradation had optimal temperature (∼25 °C in yellow earth) and increasing or decreasing temperature slowed down biodegradation rate. Overall, this study enhanced our understanding of vapor-phase biodegradation and natural attenuation of petroleum VOCs in the unsaturated zone, which is critical for the long-term management and remediation of petroleum contaminated site.

The promises, challenges and pathways to room-temperature sodium-sulfur batteries.

Room-temperature sodium-sulfur batteries (RT-Na-S batteries) are attractive for large-scale energy storage applications owing to their high storage capacity as well as the rich abundance and low cost of the materials. Unfortunately, their practical application is hampered by severe challenges, such as low conductivity of sulfur and its reduced products, volume expansion, polysulfide shuttling effect and Na dendrite formation, which can lead to rapid capacity fading. The review discusses the Na-S-energy-storage chemistry, highlighting its promise, key challenges and potential strategies for large-scale energy storage systems. Specifically, we review the electrochemical principles and the current technical challenges of RT-Na-S batteries, and discuss the strategies to address these obstacles. In particular, we give a comprehensive review of recent progresses in cathodes, anodes, electrolytes, separators and cell configurations, and provide a forward-looking perspective on strategies toward robust high-energy-density RT-Na-S batteries.

A Silicon Monoxide Lithium-Ion Battery Anode with Ultrahigh Areal Capacity.

Silicon monoxide (SiO) is an attractive anode material for next-generation lithium-ion batteries for its ultra-high theoretical capacity of 2680 mAh g-1. The studies to date have been limited to electrodes with a relatively low mass loading (< 3.5 mg cm-2), which has seriously restricted the areal capacity and its potential in practical devices. Maximizing areal capacity with such high-capacity materials is critical for capitalizing their potential in practical technologies. Herein, we report a monolithic three-dimensional (3D) large-sheet holey graphene framework/SiO (LHGF/SiO) composite for high-mass-loading electrode. By specifically using large-sheet holey graphene building blocks, we construct LHGF with super-elasticity and exceptional mechanical robustness, which is essential for accommodating the large volume change of SiO and ensuring the structure integrity even at ultrahigh mass loading. Additionally, the 3D porous graphene network structure in LHGF ensures excellent electron and ion transport. By systematically tailoring microstructure design, we show the LHGF/SiO anode with a mass loading of 44 mg cm-2 delivers a high areal capacity of 35.4 mAh cm-2 at a current of 8.8 mA cm-2 and retains a capacity of 10.6 mAh cm-2 at 17.6 mA cm-2, greatly exceeding those of the state-of-the-art commercial or research devices. Furthermore, we show an LHGF/SiO anode with an ultra-high mass loading of 94 mg cm-2 delivers an unprecedented areal capacity up to 140.8 mAh cm-2. The achievement of such high areal capacities marks a critical step toward realizing the full potential of high-capacity alloy-type electrode materials in practical lithium-ion batteries.

Fast-Charging Nonaqueous Potassium-Ion Batteries Enabled by Rational Construction of Oxygen-Rich Porous Nanofiber Anodes.

Practical applications of carbon anodes in high-power potassium-ion batteries (PIBs) were hampered by their limited rate properties, due to the sluggish K+ transport kinetics in the bulk. Constructing convenient ion/electron transfer channels in the electrode is of great importance to realize fast charge/discharge rates. Here, cross-linked porous carbon nanofibers (inner porous carbon nanotubes and outer soft carbon layer) modified with oxygen-containing functional groups were well designed as anodes to realize robust de-/potassiation kinetics. The novel anode delivered excellent rate capabilities (107 mAh g-1 at 20 A g-1 and 78 mAh g-1 at 40 A g-1) and superior cycling stability (76% capacity retention after 14,000 cycles at 2 A g-1). In situ XRD measurement, in situ Raman spectra, and galvanostatic intermittent titration verified its surface-dominated potassium storage behavior with fast de-/potassiation kinetics, excellent reversibility, and rapid ion/electron transport. Moreover, theoretical investigation revealed that the carboxyl groups in the carbon offered additional capacitive adsorption sites for K+, thus significantly enhancing the reversible capacity. Surprisingly, a full cell using the anode and perylene-3,4,9,10-tetracarboxylic dianhydride cathode achieved an outstanding power density of 23,750 W kg-1 and superior fast charge/slow discharge performance.

Dual-Carbon Electrode-Based High-Energy-Density Potassium-Ion Hybrid Capacitor.

Potassium-ion hybrid capacitors (KIHCs) have attracted growing attention due to the natural abundance and low cost of potassium. However, KIHCs are still limited by sluggish redox reaction kinetics in electrodes during the accommodation of large-sized K+. Herein, a starch-derived hierarchically porous nitrogen-doped carbon (SHPNC) anode and active carbon cathode were rationally designed for dual-carbon electrode-based KIHCs with high energy density. The hierarchical structure and rich doped nitrogen in the SHPNC anode result in a distensible interlayer space to buffer volume expansion during K+ insertion/extraction, offers more electrochemical active sites to achieve high specific capacity, and has highly efficient channels for fast ion/electron transports. The in situ Raman and ex situ TEM demonstrated a reversible electrochemical behavior of the SHPNC anode. Thus, the SHPNC anode delivers superior cycling stability and a high reversible capacity (310 mA h g-1 at 50 mA g-1). In particular, the KIHCs assembled by the SHPNC anode and commercial active carbon cathode can deliver a high energy density of 165 W h kg-1 at a current density of 50 mA g-1 and an ultra-long cycle life of 10,000 cycles at 1 A g-1 (calculated based on the total mass of the anode and cathode).

Efficacy of paclitaxel, carboplatin, and bevacizumab for cervical cancer: A protocol for systematic review and meta-analysis.

BACKGROUND: Cervical cancer (CC) is a very common and malignant tumor in female population. Although a variety of single medications are reported to treat this condition, they all have limited efficacy. Previous studies have reported the combination of paclitaxel, carboplatin, and bevacizumab (PCB) can be used for the treatment of patients with CC effectively. However, no systematic review has explored its efficacy and safety. This study will address its efficacy and safety systematically and comprehensively. METHODS: The following electronic databases will be retrieved from their inceptions to the January 1, 2020 to identify all potential associated studies: MEDLINE, EMBASE, Cochrane Library, Scopus, Web of Science, CINAHL, Google scholar, and Chinese Biomedical Literature Database. We will include randomized controlled trials (RCTs) of adult women (≥18 years) with CC globally. Eligible interventions will target any forms of PCB. The study methodological quality of all included studies will be appraised using Cochrane risk of bias tool. Statistical analysis will be undertaken using RevMan 5.3 software. In addition, we will perform a narrative synthesis to describe quality and content of the evidence. RESULTS: This study will summarize recent evidence and provide quality evidence for the efficacy and safety of PCB on CC. CONCLUSION: The findings of this study will seek to identify the efficacy and safety of PCB and suggest future directions for research efforts targeting CC among this population. SYSTEMATIC REVIEW REGISTRATION: INPLASY202040195.

Cocoon Silk-Derived, Hierarchically Porous Carbon as Anode for Highly Robust Potassium-Ion Hybrid Capacitors.

Potassium-ion hybrid capacitors (KIHCs) have attracted increasing research interest because of the virtues of potassium-ion batteries and supercapacitors. The development of KIHCs is subject to the investigation of applicable K+ storage materials which are able to accommodate the relatively large size and high activity of potassium. Here, we report a cocoon silk chemistry strategy to synthesize a hierarchically porous nitrogen-doped carbon (SHPNC). The as-prepared SHPNC with high surface area and rich N-doping not only offers highly efficient channels for the fast transport of electrons and K ions during cycling, but also provides sufficient void space to relieve volume expansion of electrode and improves its stability. Therefore, KIHCs with SHPNC anode and activated carbon cathode afford high energy of 135 Wh kg-1 (calculated based on the total mass of anode and cathode), long lifespan, and ultrafast charge/slow discharge performance. This study defines that the KIHCs show great application prospect in the field of high-performance energy storage devices.

Novel and efficient transformation of enamides into α-acyloxy ketones via an acyl intramolecular migration process.

Hydrogen peroxide and anhydride mediated transformation of enamides to afford substituted α-acyloxy ketones is described. This transition-metal-free cascade reaction has a broad substrate scope and high efficiency. The acyl intramolecular migration procedure successfully achieved this acyloxylation process under mild conditions and increased the atom efficiency.

KHCO3 - and DBU-Promoted Cascade Reaction to Synthesize 3-Benzyl-2-phenylquinolin-4(1 H)-ones.

A novel and convenient one-pot route for the synthesis of 3-benzyl-2-phenylquinolin-4(1 H)-ones has been developed under transition-metal-free conditions. This new strategy features high yield and good functional group tolerance. In addition, a proposed mechanism has been confirmed for this reaction.

Copper-Mediated Aerobic Oxidative Synthesis of 3-Bromo-imidazo[1,2-a]pyridines with Pyridines and Enamides.

A conversion of pyridines and enamides for the synthesis of 3-bromo-imidazo[1,2-a]pyridines was developed by copper-mediated aerobic oxidative coupling in a one-pot manner. This procedure tolerates various functional groups and affords a series of 3-bromo-imidazo[1,2-a]pyridines under mild conditions.