Electrochemical Realization of 3D Interconnected MoS_(3)/PPy Nanowire Frameworks as Sulfur-Equivalent Cathode Materials for Li-S Batteries

The development of freestanding and binder-free electrode is an effective approach to perform the inherent capacity of active materials and promote the mechanism study by minimizing the interference from additives.Herein,we construct a freestanding cathode composed of MoS_(3)/PPy nanowires(NWs)deposited on porous nickel foam(NF)(MoS_(3)/PPy/NF)through electrochemical methods,which can work efficiently as sulfur-equivalent cathode material for Li-S batteries.The structural stability of the MoS_(3)/PPy/NF cathode is greatly enhanced due to its significant tolerance to the volume expansion of MoS_(3)during the lithiation process,which we ascribe to the flexible 3D framework of PPy NWs,leading to superior cycling performance compared to the bulk-MoS_(3)/NF reference.Eliminating the interference of binder and carbon additives,the evolution of the chemical and electronic structure of Mo and S species during the discharge/charge was studied by X-ray absorption near-edge spectroscopy(XANES).The formation of lithium polysulfides was excluded as the driving cathode reaction mechanism,suggesting the great potential of MoS_(3)as a promising sulfur-equivalent cathode material to evade the shuttle effect for Li-S batteries.The present study successfully demonstrates the importance of structural design of freestanding electrode enhancing the cycling performances and revealing the corresponding mechanisms.

城市土壤重金属研究进展

基于文献计量法探究城市土壤重金属研究的热点、修复技术与关键问题。城市土壤重金属污染是能有效反映城市环境污染状况的重要指标之一,城市土壤重金属生态地球化学、环境风险和污染修复是目前研究的热点和焦点。城市土壤与重金属微界面过程及机制、城市土壤重金属生物有效性及其健康风险以及城市土壤重金属复合污染效应、作用机理及其污染控制是目前城市土壤重金属研究有待解决的关键科学问题。城市土壤重金属研究仍然是今后环境科学研究的热点方向,而我国西部地区的研究有待加强。

西北典型河谷型城市儿童行为及血铅水平认识调查研究

目的：调查中国西北地区典型河谷型城市儿童行为，了解儿童家长对血铅问题的认识。方法对西北部典型河谷型城市0～6岁儿童及其抚养人进行采访调查，并填写调查问卷。用Excel 2010录入数据库，并用SPSS19．0进行数据统计与分析。结果部分儿童出现血铅超标症状，且经常接触彩色塑料玩偶或电动玩具的儿童出现血铅超标症状的概率较大。不同性别儿童行为差异较大，相较于女童，男童平均每天室外活动时间更长，平均每天洗手次数更少。父母文化水平越高，对孩子血铅水平越重视。不同城市父母对儿童血铅问题认知程度不同。结论西北地区典型河谷型城市，儿童血铅问题父母重视不够，宣传儿童血铅知识和血铅超标预防工作仍待加强。

铅污染不同粒径土壤的重金属地球化学行为与风险

通过湿法提取铅污染土壤中的细砂粒、粉粒、粗粘粒和细粘粒组分,利用激光粒度分析仪、透射电镜(TEM)、X射线衍射仪(XRD)、傅里叶红外光谱(FTIR)和重金属形态连续提取的BCR方法,研究不同粒径细砂粒、粉粒、粗粘粒和细粘粒组分的重金属含量分布、矿物组成、形态分布与化学活性、迁移累积特征、生态健康风险等.结果表明,铅污染土壤中细砂粒、粉粒、粗粘粒和细粘粒组分随着颗粒物粒径的减少,总有机碳和重金属含量升高,其累积因子、活性系数和潜在生态风险指数也相对增大,特别是重金属铅的可氧化态含量显著升高.而可交换态重金属Cr、Cu、Zn则在大粒径组分中的含量较高.从综合潜在生态风险来看,铅污染土壤重金属元素在不同粒径细颗粒组分中,具有极强的潜在生态风险,在粒径特别小的纳米级天然细粘粒组分中重金属Pb和Cu具有更大的累积因子、活性系数和潜在生态风险,应采取有效措施对铅污染土壤重金属污染进行修复与治理.

Prompt Electrodeposition of Ni Nanodots on Ni Foam to Construct a High-Performance Water-Splitting Electrode:Efficient, Scalable,and Recyclable

In past decades,Ni-based catalytic materials and electrodes have been intensively explored as low-cost hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)catalysts for water splitting.With increasing demands for Ni worldwide,simplifying the fabrication process,increasing Ni recycling,and reducing waste are tangible sustainability goals.Here,binder-free,heteroatom-free,and recyclable Ni-based bifunctional catalytic electrodes were fabricated via a one-step quick electrodeposition method.Typically,active Ni nanodot(NiND)clusters are electrodeposited on Ni foam(NF)in Ni(NO3)2 acetonitrile solution.After drying in air,NiO/NiND composites are obtained,leading to a binder-free and heteroatom-free NiO/NiNDs@NF catalytic electrode.The electrode shows high efficiency and long-term stability for catalyzing hydrogen and oxygen evolution reactions at low overpotentials(10ηHER= 119 mV and 50ηOER=360 mV)and can promote water catalysis at 1.70 V@ 10mA cm-2.More importantly,the recovery of raw materials(NF and Ni(NO3)2)is quite easy because of the solubility of NiO/NiNDs composites in acid solution for recycling the electrodes.Additionally,a large-sized(S^70 cm2)NiO/NiNDs@NF catalytic electrode with high durability has also been constructed.This method provides a simple and fast technology to construct high-performance,low-cost,and environmentally friendly Ni-based bifunctional electrocatalytic electrodes for water splitting.

Enhanced Catalytic Activity of Gold@Polydopamine Nanoreactors with Multi-compartment Structure Under NIR Irradiation

Photothermal conversion(PTC)nanostructures have great potential for applications in many fields,and therefore,they have attracted tremendous attention.However,the construction of a PTC nanoreactor with multi-compartment structure to achieve the combination of unique chemical properties and structural feature is still challenging due to the synthetic difficulties.Herein,we designed and synthesized a catalytically active,PTC gold(Au)@polydopamine(PDA)nanoreactor driven by infrared irradiation using assembled PS-b-P2VP nanosphere as soft template.The particles exhibit multi-compartment structure which is revealed by 3D electron tomography characterization technique.They feature permeable shells with tunable shell thickness.Full kinetics for the reduction reaction of 4-nitrophenol has been investigated using these particles as nanoreactors and compared with other reported systems.Notably,a remarkable acceleration of the catalytic reaction upon near-infrared irradiation is demonstrated,which reveals for the first time the importance of the synergistic effect of photothermal conversion and complex inner structure to the kinetics of the catalytic reduction.The ease of synthesis and fresh insights into catalysis will promote a new platform for novel nanoreactor studies.

A Re-Configurable Dual-Mode Delay-Aware Scheduling and Resource Allocation for LTE System

Long Term Evolution( LTE) has been proposed as an advanced wireless radio access technology to provide higher peak data rates and better spectral utilization efficiency,but the classical scheduling and resource allocation algorithms cannot optimally enhance the system performance due to high computational complexity. In this paper,a re-configurable dual mode delay-aware( CDD) scheduling and resource allocation algorithm is proposed to achieve the joint consideration of scheduling pattern,scheduling priority and quantity of scheduled data. In this study,dual-mode scheduling mechanism is associated with three configurable parameters and the CDD algorithm is involved to guarantee queuing delay with low loss of resource utilization and fairness.The computational cost of the scheduling and resource allocation algorithm is significantly reduced by efficiently utilizing Qo S Class Identifier( QCI) and Channel Quality Indicator( CQI) defined by LTE standards. The simulation results based on different application scenarios also represent the computation cost and complexity of scheduling algorithm along with the improved system throughput.

Electroconductive RGO-MXene membranes with wettabilityregulated channels: improved water permeability and electro-enhanced rejection performance

Reduced graphene oxide(RGO)membranes are theoretically more conducive to the rapid transport of water molecules in their channels compared with graphene oxide(GO)membranes,as they have fewer oxygen-containing functional groups and more non-oxidized regions.However,the weak hydrophilicity of RGO membranes inhibits water entry into their channels,resulting in their low water permeability.In this work,we constructed wettable RGO-MXene channels by intercalating hydrophilic MXene nanosheets into the RGO membrane for improving the water permeance.The RGO-MXene composite membrane exhibits high pure water permeance of 62.1 L/(m^(2)·h·bar),approximately 16.8 times that of the RGO membrane(3.7 L/(m^(2)·h·bar)).Wettability test results and molecular dynamics simulations suggest that the improved water permeance results from the enhanced wettability of RGO-MXene membrane and increased rate of water molecules entering the RGOMXene channels.Benefiting from good conductivity,the RGO-MXene membrane with electroassistance exhibits significantly increased rejection rates for negatively charged dyes(from 56.0%at 0 V to 91.4%at 2.0 V for Orange G)without decreasing the permeate flux,which could be attributed to enhanced electrostatic repulsion under electro-assistance.

Electrochemically enhanced adsorption of PFOA and PFOS on multiwalled carbon nanotubes in continuous flow mode

It is important to develop efficient technologies on removal of perfluorooctanoic acid(PFOA)and perfluorooctane sulfonate(PFOS)from water due to their wide distribution and potential threat to human health.In this work,a durable and convenient electrosorption device was designed in continuous flow mode to investigate the adsorption of PFOX(X=A and S)on multiwalled carbon nanotubes(MWNTs)from water under electrochemical assistance.The electrosorption experiments were conducted under different influent and electrolyte concentrations,hydraulic retention time(HRT)and electrode distance to optimize the operation.The results showed that the highest removal efficiencies toward both PFOA and PFOS could come up to 90%at 1 V.Compared with open circuit(OC)adsorption under the same conditions,the removal efficiencies were improved by 4.9 times(PFOA)and 4.2 times(PFOS)respectively.In addition,the MWNTs electrode was found to be reusable.These findings provide an efficient method to remove PFOX from water by electrosorption in continuous flow mode.

Comparison of CNT-PVA membrane and commercial polymeric membranes in treatment of emulsified oily wastewater

Membrane separation is an attractive technique for removal of emulsified oily wastewater.However,polymeric membranes which dominate the current market usually suffer from severe membrane fouling.Therefore,membranes with high fouling resistance are imperative to treat emulsified oily wastewater.In this study,carbon nanotube-polyvinyl alcohol(CNT-PVA)membrane was fabricated.And its separation performance for emulsified oily wastewater was compared with two commercial polymeric membranes(PVDF membrane and PES membrane)by filtration of two homemade emulsions and one cutting fluid emulsion.The results show that these membranes have similar oil retention efficiencies for the three emulsions.Whereas,the permeation flux of CNT-PVA membrane is 1.60 to 3.09 times of PVDF membrane and 1.41 to 11.4 times of PES membrane,respectively.Moreover,after five consecutive operation circles of filtration process and back flush,CNT-PVA membrane can recover 62.3% to 72.9% of its initial pure water flux.However,the pure water flux recovery rates are only 24.1% to 35.3% for PVDF membrane and 6.0% to 26.3% for PES membrane,respectively.Therefore,CNT-PVA membrane are more resistant to oil fouling compared with the two polymeric membranes,showing superior potential in treatment of emulsified oily wastewater.

Carbon nanotubes-incorporated MIL-88B-Fe as highly efficient Fenton-like catalyst for degradation of organic pollutants

Iron-based metal organic frameworks have been verified to be efficient heterogeneous Fenton catalysts due to their open pore channels and highly uniform distribution of metallic centers.In these catalysts,however,the iron element is mainly in the form of Fe(III),which results in a process required to reduce Fe(III)to Fe(II)to initiate Fenton reaction.To address this problem,carbon nanotubes(CNTs)with electron-rich oxygen-functional groups on the surface were incorporated into the metal organic frameworks(MIL-88B-Fe)to improve Fe(II)content for an enhanced Fenton-like performance.The prepared CNT@MIL-88B-Fe(C@M)showed much stronger catalytic ability toward H2O2 than MIL-88B-Fe.The pseudo-first-order kinetic constant for phenol degradation by C@M(0.32 min–1)was about 7 times that of MIL-88B-Fe,and even higher than or comparable to the values of reported heterogeneous Fenton-like catalysts.Moreover,the Fenton-like system could effectively degrade various kinds of refractory organic pollutants and exhibited excellent catalytic activity over a wide pH range(4–9).XPS analysis confirmed that Fe(II)content of the catalyst gradually increased with CNT loadings.Electron spin resonance analysis showed that the signal intensity(?OH)of C@M was much higher than MIL-88B-Fe,which was consistent with the degradation efficiency of pollutants.Furthermore,the Fe(II)content of the catalyst gradually increased along with the oxygen-functional group content of CNTs.The result demonstrated that oxygen-containing functional groups of CNTs have a significant impact on the enhanced catalytic performance of C@M.This study provides a new insight to enhance Fenton reaction by using nanocarbon materials.

Enhanced activation of peroxymonosulfate by CNT-TiO2 under UV-light assistance for efficient degradation of organic pollutants

In this work,a UV-light assisted peroxymonosulfate(PMS)activation system was constructed with the composite catalyst of multi-walled carbon nanotubes(CNT)-titanium dioxide(TiO2).Under the UV light irradiation,the photoinduced electrons generated from TiO2 could be continuously transferred to CNT for the activation of PMS to improve the catalytic performance of organic pollutant degradation.Meanwhile,the separation of photoinduced electron-hole pairs could enhance the photocatalysis efficiency.The electron spin resonance spectroscopy(EPR)and quenching experiments confirmed the generation of sulfate radical(SO4 ?),hydroxyl radical( OH)and singlet oxygen(1O2)in the UV/PMS/20%CNT-TiO2 system.Almost 100%phenol degradation was observed within 20 min UV-light irradiation.The kinetic reaction rate constant of the UV/PMS/20%CNT-TiO2 system(0.18 min?1)was 23.7 times higher than that of the PMS/Co3O4 system(0.0076 min?1).This higher catalytic performance was ascribed to the introduction of photoinduced electrons,which could enhance the activation of PMS by the transfer of electrons in the UV/PMS/CNT-TiO2 system.

Electro-assisted CNTs/ceramic flat sheet ultrafiltration membrane for enhanced antifouling and separation performance

Ultrafiltration is employed as an important process for water treatment and reuse,which is of great significance to alleviate the shortage of water resources.However,it suffers from severe membrane fouling and the trade-off between selectivity and permeability.In this work,a CNTs/ceramic flat sheet ultrafiltration membrane coupled with electro-assistance was developed for improving the antifouling and separation performance.The CNTs/ceramic flat sheet membrane was fabricated by coating cross-linked CNTs on ceramic membrane,featuring a good electroconductivity of 764.75 S/m.In the filtration of natural water,the permeate flux of the membrane with the cell voltage of-2.0 V was 1.8 times higher than that of the membrane without electro-assistance and 5.7-fold greater than that of the PVDF commercial membrane.Benefiting from the electro-assistance,the removal efficiency of the typical antibiotics was improved by 50%.Furthermore,the electro-assisted membrane filtration process showed 70%reduction in energy consumption compared with the filtration process of the commercial membrane.This work offers a feasible approach for membrane fouling mitigation and effluent quality improvement and suggests that the electro-assisted CNTs/ceramic membrane filtration process has great potential in the application of water treatment.

Optical emission spectroscopy diagnosis of energetic Ar ions in synthesis of SiC polytypes by DC arc discharge plasma

Silicon carbides are basilic ceramics with proper bandgaps （2.4-3.3 eV） and unique optical properties. SiC@C monocrystal nanocapsules with different morphologies, sizes, and crystal types were synthesized via the fast and facile direct current （DC） arc discharge plasma method. The influence of Ar atmosphere on the formation of nanocrystal SiC polytypes was investigated by optical emission spectroscopy （OES） diagnoses on the arc discharge plasma. Boltzmann＇s plot was used to estimate the temperatures of plasma containing different Ar concentrations as 10,582 K （in 2 × 10^4 Pa of Ar partial pressure） and 14,523 K （in 4 × 10^4 Pa of Ar partial pressure）. It was found that higher energy state of plasma favors the ionization of carbon atoms and promotes the formation of α-SiC, while β-SiC is generally coexistent. Heat-treatment in air was applied to remove the carbon species in as-prepared SiC nanopowders. Thus, the intrinsic characters of SiC polytypes reappeared in the ultraviolet-visible （UV-vis） light absorbance. It was experimentally revealed that the direct bandgap of SiC is 5.72 eV, the indirect bandgap of β-SiC （3C） is 3.13 eV, and the indirect bandgap of α-SiC （6H） is 3.32 eV; visible quantum confinement effect is predicted for these polytypic SiC nanocrystals.

Interface evolution in the platelet-like SiC@C and SiC@ SiO2 monocrystal nanocapsules

Carbon-coated SiC@C nanocapsules （NCs） with a hexagonal platelet-like morphology were fabricated by a simple direct current （DC） arc-discharge plasma method. The SiC@C NCs were monocrystalline, 120-150 nm in size, and approximately 50 nm thick. The formation of the as-prepared SiC@C NCs included nucleation of truncated octahedral SiC seeds and subsequent anisotropic growth of the seeds into hexagonal nanoplatelets in a carbon-rich atmosphere. The disordered carbon layers on the SiC@C NCs were converted into SiO2 shells of SiC@SiO2 NCs by heat treatment at 650 ℃ in air, during which the shape and inherent characteristics of the crystalline SiC core were obtained. The interface evolution from carbon to SiO2 shells endowed the SiC@SiO2 NCs with enhanced photocatalytic activity due to the hydrophilic and transparent nature of the SiO2 shell, as well as to the photosensitive SiC nanocrystals. The band gap of the nanostructured SiC core was determined to be 2.70 eV. The SiC@SiO2 NCs degraded approximately 95% of methylene blue in 160 min under visible light irradiation.

Partner switching for Ran during the mitosis dance

Mitosis is one of the most fascinating pro- cesses in biology, and is often described as a well-choreographed dance. During mitosis, sister chromatids attach to dynamic microtubules in the mitotic spindle, align and oscillate at the metaphase plate, separ- ate synchronously at the metaphase-ana- phase transition, and are partitioned equally into the two daughter cells. Chromosome missegregation leads to aneuploidy and genomic instability, which can drive tumori- genesis under certain contexts.

Enhancing anoxic denitrification of low C/N ratio wastewater with novel ZVI composite carriers

External organic carbon sources are needed to provide electron donors for the denitrification of wastewater with a low COD/NO_(3)^(-)-N(C/N)ratio,increasing the treatment cost.The economic strategy is to enhance the bioactivity and/or biodiversity of denitrifiers to efficiently utilize organic substances in wastewater.In this study,novel zero-valent iron(ZVI)composite carriers were prepared and implemented in a suspended carrier biofilm reactor to enhance the bioactivity and/or biodiversity of denitrifiers.At the influent C/N ratio of 4(COD was 179.5±5.0 mg/L and TN was 44.2±0.8 mg/L),COD and TN removal efficiencies were 85.1%and 66.4%,respectively,in the reactors filled with 3 wt%ZVI composite carriers.In contrast,COD and TN removal efficiencies were 70.4%and 55.3%,respectively,in the reactor filled with conventional high-density polyethylene(HDPE)biofilm carriers.The biofilm formation on the 3 wt%ZVI composite carriers was optimized due to its higher roughness(surface square roughness increased from 76.0 nm to 93.8 nm)and favorable hydrophilicity(water contact angle dropped to 72.5°±1.4°from 94.3°±3.2°)compared with the HDPE biofilm carriers.In addition,heterotrophic denitrifiers,Thauera and Dechloromonas,were enriched,whereas autotrophic denitrifiers,Raoultella and Thiobacillus,exhibited high relative abundance in the biofilm of ZVI composite carriers.The coexistence of heterotrophic denitrifiers and autotrophic denitrifiers on the surface of ZVI composite carriers provided mixotrophic metabolism of denitrification(including heterotrophic and iron-based autotrophic),thereby ensuring effective denitrification for wastewater with a low C/N ratio without external organic carbon source addition.

Utilizing transparent and conductive SnO2 as electron mediator to enhance the photocatalytic performance of Z-scheme Si-SnO2-TiOx

Z-scheme photocatalysts,with strong redox ability,have a great potential for pollutants degradation.However,it is challenging to construct efficient Z-scheme photocatalysts because of their poor interfacial charge separation.Herein,by employing transparent and conductive SnO2 as electron mediator to pass light through and promote interfacial charge transportation,a novel Z-scheme photocatalyst Si-SnO2-TiOx(i<x<2)was constructed.The Z-scheme photocatalyst displayed an order of magnitude higher photocurrent density and a 4-fold increase in open-circuit potential compared to those of Si.Moreover,the onset potential shifted negatively for approximately 2.2 V.Benefiting from these advantages,this Z-scheme Si-SnO2-TiOx exhibited efficient photocatalytic performance toward phenol degradation and mineralization.15%of the phenol was degraded without bias potential and 70%of the TOC was removed during phenol degradation.Other typical pollutants such as bisphenol A and atrazine could also be degraded without bias potential.Introducing a transparent and conductive electron mediator to construct Z-scheme photocatalyst gives a new sight to the improvement of photocatalytic performance in Z scheme.

Fabrication of quantum-sized Cd S-coated Ti O2 nanotube array with efficient photoelectrochemical performance using modified successive ionic layer absorption and reaction(SILAR) method

Quantum-sized CdS-coated TiO2 nanotube array （Q-CdS-TiO2 NTA） was fabricated by the modified successive ionic layer absorption and reaction method. Scanning electron microscope and transmission electron microscope images showed the regular structure of TiO2 NTA, where quantum-sized CdS （diameter 〈10nm） deposited on both the inside and outside of TiO2 nanotube wall. Fabrication conditions including immersing cycles, calcination temperature and drying process were well optimized, and the Q-CdS-TiO2 NTA and its photoelectrochemical （PEC） properties were characterized by X-ray fluorescence spectrometer, UV-Vis diffuse reflectance spectra and photovoltage. Distinct increases in visible light absorption and photocurrent were observed as the immersing cycle was increased from 5 to 20 times. The additional drying process accelerated the CdS crystal growth rate, and thus, the fabrication time could be shortened accordingly. Calcination temperature influenced the PEC property of Q-CdS-TiO2 NTA deeply, and the optimized calcination temperature was found as 500 ℃. As the Q-CdS-TiO2 NTA was fabricated under such condition, the visible photocurrent density increased to 2.8 mA/cm and the photovoltage between 350 and 480 nm was enhanced by 2.33 times than that without calcination. This study is expected to optimize Q-CdS-TiO2 NTA fabrication conditions for the purpose of improving its PEC performance.

Relaxor behavior and Raman spectra of CuO-doped Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)ferroelectric ceramics

In this work,Raman spectra and dielectricity-temperature dependence measurements were used to investigate the B-site order degree in CuO-doped Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)ferroelectric ceramics.The measurement results indicated a typical relaxor characteristic for all samples.With the increasing of CuO doping content,the B-site order degree increased first and then decreased.However,the frequency dispersion and the relaxation degree decreased first and then increased while the CuO addition content was increasing,which was thought to be strongly correlated with the variations of the B-site order.The opposite variation tendency of the B-site order degree and the relaxation degree revealed that the phase transition dispersity is closely related to the order-disorder behaviors.