A brannerite type cobalt vanadate conversion anode for lithium batteries

The vanadium-based oxide compounds involved in the conversion reaction deserve the most attention in fabricating anode material for lithium batteries. This work is concentrated on the electrochemically driven conversion reaction mechanism behind the brannerite type CoV₂O₆ anode material synthesized by hydrothermal method. It exhibits an initial irreversible capacity of 939 mAh g^?1; however, a 40 % capacity fading has been observed in the second cycle with retention of 80 % up to the 30th cycle. The reversible discharge capacity in the second cycle is still more than the theoretical capacity of cobalt vanadate. The conversion reaction of CoO nano-particles into Co quantum dots resided in amorphous lithiated vanadium oxide matrix acted as a reactive site as well as the separator to preserve the nano-particles from further agglomeration, then better rate capability. The brannerite type conversion electrode material with such features may give light on the search of a new anode for Li batteries.     

Design, synthesis and biological activity of cyclohexane-bearing C-glucoside derivatives as SGLT2 inhibitors

Seven cyclohexane-bearing C-glucoside derivatives (7, 9, 12, 13 and 17-19) were designed and synthesized as SGLT2 inhibitors starting from a potent SGLT2 inhibitor we discovered in earlier work, (1S)-1-deoxy-1-[4-methoxy-3-(trans-n-propylcyclohexyl)methylphenyl]-D-glucose (1). The in vitro and in vivo biological activities were evaluated by hSGLT2/hSGLT1 inhibition and urinary glucose excretion (UGE), respectively. Among the synthesized compounds 12, the 6-deoxy derivative of 1 was the most active and selective SGLT2 inhibitor (IC50 = 1.4 nmol/L against hSGLT2; selectivity = 1576). Compound 12 was a potent SGLT2 inhibitor, which could induce more urinary glucose than 1 and dapagliflozin in UGE.     

数学模拟方法研究导电剂形貌对锂离子电池高倍率放电性能的影响

制备了正极中只含有一种导电剂(KS-6或Super-P)的锂离子电池,比较了它们的倍率放电性能并对放电过程进行了模拟。以Super-P为正极导电剂的电池15C放电容量为1C容量的84.3%,以KS-6为正极导电剂的电池15C放电容量为1C容量的21.8%,前者的倍率放电性能明显优于后者。数学模拟结果显示,以KS-6为导电剂的正极的Bruggeman系数为3.1,以Super-P为导电剂的正极的Bruggeman系数为2.76,前者明显大于后者,认为这是由于KS-6的片状形貌使其容易相互平行排列造成的。大电流放电时,以KS-6为导电剂的正极中出现了电解质耗竭而导致该区域内电化学反应停止的现象,从而导致电池放电容量急剧降低。     

Synthesis and Crystal Structure of 2-[（2-Chloropyridin-4-yl）oxy]-3,3-diphenyl-3-methoxypropionic Acid

The title compound was synthesized and its crystal structure was determined by single-crystal X-ray diffraction.The crystal is of orthorhombic system(C21H18ClNO4,Mr = 383.81),space group Pca21 with a = 13.913(3),b = 10.273(2),c = 26.488(5),V = 3786.1(13) 3,Z = 8,Dc = 1.347 g/cm3,F(000) = 1600,μ = 0.228 mm-1,the final R = 0.0550 and wR = 0.1278 for 5065 observed reflections(I > 2σ(I)).The title compound in a racemic form was found to exist as a mixture of two enantiomers in an equal ratio in the unit cell.The intermolecular hydrogen bonds link the molecules in a head-to-end manner to generate an infinite chain.     

Structural response of polyelectrolyte dendrimer towards molecular protonation: the inconsistency revealed by SANS and NMR

Polyamidoamine (PAMAM) dendrimers and their charged state in deuterium oxide have been investigated with proton pulsed field gradient diffusion nuclear magnetic resonance (PFG-NMR) and small-angle neutron scattering (SANS) techniques. NMR measurements suggest that significant variation of the hydrodynamic radius, calculated by the Stokes-Einstein relation with appropriate surface conditions, is observed upon increasing the molecular protonation. However, a comparative SANS experiment indicates little dependence of the dendrimer global size, in terms of its radius of gyration, on molecular protonation. The inconsistency indicates the necessity of incorporating the effect of molecular interface modification and molecular porosity provided by dressed counterions, when dynamical measurements are used for the determination of the structural characteristics of ionic soft colloids even in dilute suspensions.     

Electric and magnetic dipole couplings in split ring resonator metamaterials

In this paper, the electric and the magnetic dipole couplings between the outer and the inner rings of a single split ring resonator (SRR) are investigated. We numerically demonstrate that the magnetic resonance frequency can be substantially modified by changing the couplings of the electric and magnetic dipoles, and give a theoretical expression of the magnetic resonance frequency. The results in this work are expected to be conducive to a deeper understanding of the SRR and other similar metamaterials, and provide new guidance for complex metamaterials design with a tailored electromagnetic response.     

微波辐射法制备Cu-SSZ-13催化剂及其对柴油车尾气NOx的脱除

采用微波辐射法和传统水热法分别制备了Cu-SSZ-13催化剂,用于柴油车尾气NO_x的脱除.用X射线衍射(XRD)、N₂物理吸脱附、H₂程序升温还原(H₂-TPR)、电子顺磁共振(EPR)、NH₃程序升温脱附(NH₃-TPD)、电感耦合等离子体质谱(ICP-MS)及X射线光电子能谱(XPS)等方法对样品进行表征.结果表明,微波辐射法大大缩短了SSZ-13分子筛的晶化时间,晶化9 h制得样品的结晶度与传统水热法晶化72 h制得样品的结晶度相近,同时孔结构参数也得到了一定程度的改善,微波辐射法制备样品的Brönsted(B)酸性位和Lewis(L)酸性位增多,活性组分铜的负载量也得到显著的提高,使得微波辐射法制备的催化剂呈现出优异的低温活性和水热稳定性.     

喷雾夹角对柴油机性能影响的数值模拟

为研究喷雾夹角对柴油机性能的影响,应用STAR-CD程序对不同喷雾夹角的燃烧过程进行三维数值模拟.计算结果表明喷雾夹角决定了油束在燃烧室的空间分布和燃油与壁面的碰撞参数,进而影响到燃油的雾化与燃烧.当碰撞距离增加,燃油雾化时间增加.当撞壁入射角度减小,燃油壁面涂布能力增强,促进燃油蒸发雾化.当油束将燃烧室有效容积等分时,油气混合均匀,具有良好的燃烧效果.     

苯甲醛肟与炔丙醇偶极环加成反应的理论研究

用密度泛函理论(DFT)方法在B3LYP/6-31G*水平上研究了苯甲醛肟与炔丙醇加成反应的微观机制和热力学、动力学行为. 结果表明, 在苯甲醛肟与炔丙醇加成反应过程中, 8个可能反应通道的过渡态中均形成非平面五元环结构, 其中苯甲醛肟的Z、E构型特征得到了部分保留, 但主要部分的键长、键角均发生了变化, 电荷也进行了重新分布. 苯甲醛肟以羟基型参与反应的4个反应通道均为吸热反应和热力学非自发过程, 它们均具有较高的反应势垒、较慢的反应速率和较小的平衡常数; 而以离子型参与反应的四个反应通道均为放热反应和热力学自发过程, 它们的反应势垒较低, 反应速度较快, 平衡常数也较大, 故苯甲醛肟应主要以离子型参与反应. 炔丙醇的两种取向对应着加成反应的两种产物, 反应达到平衡后, 3-羟甲基二氢异噁唑为主要产物.     

Eu3+掺杂的Sr2CeO4发光材料的光致发光研究

利用高温固相反应法制备了Eu3+掺杂的Sr2CeO4样品,并对其吸附水前后的光谱特性进行了研究.结果发现,对于刚制备的Sr2-xEuxCeO4+x/2样品, 在Ce4+-O2-的电荷迁移激发中,只有强激发带(～35700cm-1)与Eu3+离子间存在能量传递,而弱激发带 (～29400cm-1)只是引起Ce4+-O2-的电荷迁移发射;在Sr2-xEuxCeO4+x/2样品吸附水后,Eu3+的线状吸收跃迁强度显著增加, Ce4+-O2-两个激发带均向Eu3+离子传递能量. Ce4+-O2-强激发带通过交换作用向Eu3+离子传递能量,而弱激发带与Eu3+离子间的能量传递机理是非辐射多极子近场力的相互作用.