Structural elucidation of V‐type nerve agents by liquid chromatography/electrospray ionization mass spectrometry

V‐nerve agents present information‐poor spectra, both in GC‐EI‐MS and LC‐ESI‐MS/MS, with dominant fragments/product ions corresponding to the amine‐containing residue. Hence, derivatives/isomers with the same amine residue exhibit similar mass spectral patterns, leading to ambiguity in the phosphonate structure. We present a simple approach for their structural elucidation based on two complementary experiments: ESI‐MS/MS of the original compound, which provides information about the amine moiety, and ESI‐MS/MS of the phosphonic acid hydrolysis products generated by N‐iodosuccinimide, which provides ions' characteristic of the phosphonate structure. This approach enables the structural elucidation of the original V‐agents with a higher degree of certainty.     

A High Performing Zn‐Ion Battery Cathode Enabled by In Situ Transformation of V2O5 Atomic Layers

Developing high capacity and stable cathodes is a key to successful commercialization of aqueous Zn‐ion batteries (ZIBs). Pure layered V₂O₅ has a high theoretical capacity (585 mAh g^?1), but it suffers severe capacity decay. Pre‐inserting cations into V₂O₅ can substantially stabilize the performance, but at an expense of lowered capacity. Here we show that an atomic layer deposition derived V₂O₅ can be an excellent ZIB cathode with high capacity and exceptional cycle stability at once. We report a rapid in situ on‐site transformation of V₂O₅ atomic layers into Zn₃V₂O₇(OH)₂?2 H₂O (ZVO) nanoflake clusters, also a known Zn‐ion and proton intercalatable material. High concentration of reactive sites, strong bonding to the conductive substrate, nanosized thickness and binder‐free composition facilitate ionic transport and promote the best utilization of the active material. We also provide new insights into the V₂O₅‐dissolution mechanisms for different Zn‐salt aqueous electrolytes and their implications to the cycle stability.     

A Long‐Cycling Aqueous Zinc‐Ion Pouch Cell: NASICON‐Type Material and Surface Modification

Aqueous zinc‐ion batteries (ZIBs) have become the highest potential energy storage system for large‐scale applications owing to the high specific capacity, good safety and low cost. In this work, a NASICON‐type Na₃V₂(PO₄)₃ cathode modified by a uniform carbon layer (NVP/C) has been synthesized via a facile solid‐state method and exhibited significantly improved electrochemical performance when working in an aqueous ZIB. Specifically, the NVP/C cathode shows an excellent rate capacity (e. g., 48 mAh g^?1 at 1.0 A g^?1). Good cycle stability is also achieved (e. g., showing a capacity retention of 88% after 2000 cycles at 1.0 A g^?1). Furthermore, the Zn²⁺ (de)intercalation mechanism in the NVP cathode has been determined by various ex‐situ techniques. In addition, a Zn||NVP/C pouch cell has been assembled, delivering a high capacity of 89 mAhg^?1 at 0.2 A g^?1 and exhibiting a superior long cycling stability.     

Investigation of the voltage and time effects on the formation of hydroxyapatite-containing titania prepared by plasma electrolytic oxidation on Ti-6Al-4V alloy and its corrosion behavior

Producing titania and hydroxyapatite (HA) bioceramic coating on titanium alloys increases corrosion resistance and biocompatibility of these alloys. Plasma electrolytic oxidation (PEO) is one of the effective techniques for producing this type of coating. This method produces coatings with enough thickness and appropriate adhesion. In this study, titania and HA were directly produced on Ti-6Al-4V by applying PEO process in a Ca- and P-containing electrolyte by changing voltage and time parameters. Morphology and cross section, chemical composition and elements of coatings were investigated by scanning electron microscope, X-ray diffraction and energy dispersive spectroscopy, respectively. Corrosion behavior of the samples was also examined by potentiodynamic polarization and electrochemical impedance spectroscopy. The results indicated that the formation of HA phase with titania needs a minimum voltage below which HA is not formed. By increasing the operation time, the amount of the formed HA increased. Also, the sample coated at 500 V and 15 min showed the best corrosion behavior in Ringer's solution.     

Microstructure and tribological behaviors of Ti6Al4V alloy treated by plasma Ni alloying

Ni modified layer was prepared on surface of the Ti6Al4V substrate by plasma surface alloying technique. Surface morphology, micro-structure, composition distribution, phase structure, and microhardness of the Ni modified layer were analyzed. Tribological performance of the Ni modified layer and Ti6Al4V substrate was investigated by using pin-on-disc tribometer. The results indicate that roughness of the Ni modified layer was increased due to formation of the micro-convex on the modified surface. The concentration of Ni gradually decreased from the surface to interior. The maximum content of Ni atoms was nearly 90%. The modified layer was composed of TiNi, Ti2Ni and Ti phases. The maximum microhardness of the Ni modified layer was about 677 HV_0.025 which was increased about two-fold of microhardness of the control Ti6Al4V substrate. Wear resistance of the Ni modified layer was improved obviously, and showed micro-abrasion wearing. The strengthened mechanism of the as-treated Ti6Al4V alloy is discussed.     

H6PMo9V3O40/SiO2催化剂催化酚类化合物选择性硝化

为创建洁净高效的酚类化合物硝化工艺,以杂多酸H6PMo9V3O40(PMAV3)为活性组分,硅胶为载体,浸渍法制备了负载型催化剂PMAV3/SiO2,采用红外光谱、X射线衍射谱、N2吸附-脱附法及TG-DSC分析等测试技术对该催化剂的结构及热稳定性进行了表征;考察了该催化剂对多种酚类化合物硝化反应的催化性能。结果显示,该催化剂对多种酚类化合物的硝化反应具有很强的催化活性和区域选择性,产率为83.7%~94.5%,其中苯酚、邻甲酚、邻氯苯酚和邻氟苯酚以邻位硝化产物居多,水杨酸的对位硝化产物占绝对优势;负载催化剂的织构性质与载体相近,但随负载量增加,比表面积逐渐降低;PMAV3/SiO2的热稳定性好于本体PMAV3。催化剂回收容易,重复使用5次,活性基本不变。     

低温溶剂热法制备5V级性能优异的LiCr_(0.2)Ni_(0.4)Mn_(1.4)O_4正极材料(英文)

通过低温溶剂热的方法成功制备出了LiCr0.2Ni0.4Mn1.4O4尖晶石正极材料。通过此法,溶液的饱和蒸汽压急剧降低且在室温(25℃)下即可沸腾。所有的金属离子可在随后的热聚合过程中均匀分散且煅烧后所得材料无杂质相生成。采用了热重分析,X射线衍射,扫描电镜、循环伏安,交流阻抗等测试手段对材料进行了表征。结果表明:此法所得材料含有Mn3+,为Fd3m晶型,且其形貌规则、粒度分布均一。1C和10C下放电容量为140.5和121.0 mAh·g-1,10C下100次循环容量保持率高达96.9%。其优异的电化学性能可归因于均相的前驱体制备过程,高结晶度且无杂相生成,以及较高的锂离子扩散系数诸因素的共同作用。     

Hollow fiber liquid phase microextraction combined with electrothermal atomic absorption spectrometry for the speciation of arsenic (III) and arsenic (V) in fresh waters and human hair extracts

A new method of hollow fiber liquid phase microextraction (HF-LPME) using ammonium pyrrolidine dithiocarbamate (APDC) as extractant combined with electrothermal atomic absorption spectrometry (ETAAS) using Pd as permanent modifier has been described for the speciation of As(III) and As(V). In a pH range of 3.0-4.0, the complex of As(III)-APDC complex can be extracted using toluene as the extraction solvent leaving As(V) in the aqueous layer. The post extraction organic phase was directly injected into ETAAS for the determination of As(III). To determine total arsenic in the samples, first As(V) was reduced to As(III) by l-cysteine, and then a microextraction method was performed prior to the determination of total arsenic. As(V) assay was based on subtracting As(III) form the total arsenic. All parameters, such as pH of solution, type of organic solvent, the amount of APDC, stirring rate and extraction time, affecting the separation of As(III) from As(V) and the extraction efficiency of As(III) were investigated, and the optimized extraction conditions were established. Under optimized conditions, a detection limit of 0.12 ng mL⁻¹ with enrichment factor of 78 was achieved. The relative standard deviation (R.S.D.) of the method for five replicate determinations of 5 ng mL⁻¹ As(III) was 8%. The developed method was applied to the speciation of As(III) and As(V) in fresh water and human hair extracts, and the recoveries for the spiked samples are 86-109%. In order to validate the developed method, three certified reference materials such as GBW07601 human hair, BW3209 and BW3210 environmental water were analyzed, and the results obtained were in good agreement with the certified values provided.     

A widely varying range of products in reactions of C6F5BrF2, C6F5IF2, and C6F5IF4 with Lewis acids of different strength

The relative fluoride donor ability: C₆F₅BrF₂ > C₆F₅IF₂ > C₆F₅IF₄ was outlined from reactions with Lewis acids of graduated strength in different solvents. Fluoride abstraction from C₆F₅HalF₂ with BF₃·NCCH₃ in acetonitrile (donor solvent) led to [C₆F₅HalF·(NCCH₃)_n][BF₄]. The attempted generation of [C₆F₅BrF]⁺ from C₆F₅BrF₂ and anhydrous HF or BF₃ in weakly coordinating SO₂ClF gave C₆F₅Br besides bromoperfluorocycloalkenes C₆BrF₇ and 1-BrC₆F₉. In reactions of C₆F₅IF₂ with SbF₅ in SO₂ClF the primary observed intermediate (¹⁹F NMR, below 0 °C) was the 4-iodo-1,1,2,3,5,6-hexafluorobenzenium cation, which converted into C₆F₅I and 1-IC₆F₉ at 20 °C. The reaction of C₆F₅IF₄ with SbF₅ in SO₂ClF below −20 °C gave the cation [C₆F₅IF₃]⁺ which decomposed at 20 °C to C₆F₅I, 1-iodoperfluorocyclohexene, and iodoperfluorocyclohexane. Principally, the related perfluoroalkyl compound C₆F₁₃IF₄ showed a different type of products in the fast reaction with AsF₅ in CCl₃F (−60 °C) which resulted in C₆F₁₄. Intermediate and final products of C₆F₅HalF_n−1 (n = 3, 5) with Lewis acids were characterized by NMR in solution. Stable solid products were isolated and analytically characterized.