Design and Construction of 3D Porous Na3V2(PO4)3/C as High Performance Cathode for Sodium Ion Batteries

An easy and delicate approach using cheap carbon source as conductive materials to construct 3D sequential porous structural Na3V2(PO4)3/C(NVP/C)with high performance for cathode materials of sodium ion battery is highly desired.In this paper,the NVP/C with 3D sequential porous structure is constructed by a delicate approach named as“cooking porridge”including evaporation and calcination stages.Especially,during evaporation,the viscosity of NVP/C precursor is optimized by controlling the adding quantity of citric acid,thus leading to a 3D sequential porous structure with a high specific surface area.Furthermore,the NVP/C with a 3D sequential porous structure enables the electrolyte to interior easily,providing more active sites for redox reaction and shortening the diffusion path of electron and sodium ion.Therefore,benefited from its unique structure,as cathode material of sodium ion batteries,the 3D sequential porous structural NVP/C exhibits high specific capacities(115.7,88.9 and 74.4 mA·h/g at current rates of 1,20 and 50 C,respectively)and excellent cycling stability(107.5 and 80.4 mA·h/g are remained at a current density of 1 C after 500 cycles and at a current density of 20 C after 2200 cycles,respectively).     

Multilayer Porous Vanadium Nitride Microsheets Anodes for Highly Stable Na-ion Batteries

Sodiumion batteries(SIBs)have attracted intensive attention as promising alternative to lithium-ionbatteries(LIBs)for large scale energy storage systems because of low cost of sodium,similar energy storage mechanism and the reasonable performance.However,it is still a great challenge to search and design a robust structure of anode materials with excellent cycling stability and high rate capability for SIBs.Herein,multilayer porous vanadium nitride(VN)microsheets are synthesized through a facile and scalable hydrothermal synthesis-nitrogenization strategy as an effective anode material for SIBs.The multilayer porous VN microsheets not only offer more active sites for fast Na+insertion/extraction process and short diffusion pathway,but also effectively buffer the volume change of anode due to more space in the multilayer porous structure.The large proportions of capacitive behavior imply that the Na+charge storage depends on the intercalation pseudocapacitive mechanism.The multilayer porous VN microsheets electrodes manifest excellent cycling stability and rate capability,delivering a discharge capacity of 156.1 mA·h/g at 200 mA/g after 100 cycles,and a discharge capacity of 111.9 mA·h/g at 1.0 A/g even after 2300 cycles with the Coulombic efficiency of nearly 100%.     

Host-Guest Interactions of Cyclopentanocucurbit[6]uril with Alkyl Imidazolium Hydrochlorides

The host-guest interactions between cyclopentanocucurbit-[6]uril(CyP₆Q[6]) as host and six alkyl imidazolium hydrochloride as guests(g1, g2, g3, g4, g5, and g6) have been studied by various techniques, such as ¹H NMR spectroscopy, isothermal titration calorimetry, mass spectrometry, and single-crystal X-ray diffraction analysis. The experimental results showed that CyP₆Q[6] formed 1:1 inclusion complexes with each of guests g1-g6. The part of the guest entered the cavity of CyP₆Q[6] changes as the alkyl chain increases in length. It can be seen that the length of the alkyl chain plays a key role in determining the mode of host-guest interactions.     

混合熔盐法低温合成Sm2Ti2S2O5及其光催化分解水产氢

以TiO2、TiS2及Sm2O3为前驱体,分别加入LiCl-KCl与LiCl-CsCl的最低共熔混合物作为熔盐,在较低温度下成功合成了Sm2Ti2S2O5(STSO)颗粒。通过对比不同温度下所制备产物的X射线衍射图,首次表明STSO的热力学结晶温度在520℃左右,远低于之前报道的650℃的最低合成温度。扫描电子显微镜照片显示,采用2种混合熔盐制备的STSO都呈片状形貌;同一合成温度下,采用LiCl-CsCl熔盐制备的STSO的厚度小于LiCl-KCl所得产物。采用出射光波长大于420 nm的氙灯作为光源,在含有Na2S-Na2SO3空穴牺牲剂的溶液中,所制备的STSO颗粒表现出最高35μmol·h-1的光催化分解水产氢活性以及20 h以上的产氢稳定性。     

含二茂铁基的硫代碳酰腙和缩氨基硫脲的合成

硫代碳酰腙和氨基硫脲衍生物具有一定的生理活性,可作为某些金属离子的特效试剂,本文报道在乙醇-醋酸介质中通过取代氨基硫脲,硫代碳酰腙与不同的二茂铁衍生物缩合,合成了新的缩氨基硫脲和硫代碳酰腙衍生物.     

含侧链手性噁唑硼烷催化还原苯乙酮对映选择性的理论研究

用AMI方法研究了含侧链手性恶唑硼烷催化苯乙酮还原反应的对映选择性机理 及其取代基和构型对对映选择性的影响。计算结果表明，含侧链手性恶唑硼烷催化 还原苯乙酮的反应机理与Corey等人提出的机理相符合，在此类硼催化剂的作用下 ，苯乙酮还原产物的绝对构型以R型为主。当恶唑硼烷环N(3)，B(2)上无取代基时 ，C(4)，C(5)位的取代基及其构型是不对称催化反应对映选择性的主要影响因素。     

Catalytic Asymmetric[2,3]-Sigmatropic Rearrangement of Sulfur Ylides Generated from Carbenoids and Allenic 2-Methylphenyl Sulfide

The first investigation on catalytic asymmetric [2, 3]-sigmatrop-ic rearrangement of sulfur ylides generated from carbenoids andallenic phenyl sulfide was carried out. Up to 55% ee value wasobtained.     

A rapid method for determining recent sunscreen use in field studies

The role of sunscreens in preventing skin cancer and melanoma is the focus of ongoing research. Currently, there is no objective measure which can be used in field studies to determine whether a person has applied sunscreen to their skin, and researchers must use indirect assessments such as questionnaires. We sought to develop a rapid, non-invasive method for identifying sunscreen on the skin for use in epidemiological studies. Our basic method is to swab the skin, elute any residues which have been adsorbed onto the swab by rinsing in ethanol, and submit the eluted washings for spectrophotometric analysis. In a controlled study, we applied 0.1 ml of sunscreen to a 50 cm(2) grid on both forearms of 21 volunteers. Each forearm was allocated one of 10 different sunscreen brands. The skin was swabbed after intervals of 20 min, 1 h, 2 h and 4 h. In a field study conducted among 12 children aged 2-4 years attending a child care centre, sunscreen was applied to the faces of half the children. Swabs were then taken from the face and back of all children without knowledge of sunscreen status. In the controlled study, sunscreen was clearly detectable up to 2 h after application for all brands containing organic sunscreen, and marginally detectable at 4 h. In the field study, this method correctly identified all children with and without sunscreen. We conclude that spectrophotometric analysis of skin swabs can reliably detect the presence of sunscreen on the skin for up to 2 h after application.     

(SO4.-)诱导含硫三电子键自由基的生成机理研究

运用２４８ｎｍ激光光解瞬态吸收光谱,研究了ＳＯ４＾·－单电子氧化Ｄ－甲硫氨酸＊Ｍｅｔ）、Ｌ－甲硫氨酸甲酯（ＭＭＥ）和甲硫氨酰甲硫氨酸（Ｍｅｔ－Ｍｅｔ）的反应过程。观察到反应过程中生成３种含硫三电子键自由基中间体,［Ｓ∴Ｓ］＾＋、［Ｓ∴Ｎ］＾＋［Ｓ∴Ｏ］,并分析了反应机理。     

丙烯醇等离子体处理聚四氟乙烯的表面结构与润湿性

聚四氟乙烯经丙烯醇等离子体处理后,在其表面形成了一层亲水性的聚合物薄膜。水在表面的接触角为40—60°不等,由等离子体处理时间决定。对表面的全反射红外光谱、ESCA分析和SEM观测发现,等离子体处理后在原表面上形成的聚合物膜包含—CH_3、—CH_2、C=O和C—OH等基团,并且表面光滑、平整。