3D Starfish-Like FeOF on Graphene Sheets: Engineered Synthesis and Lithium Storage Performance

To address the problems associated with poor conductivity and large volume variation in practical applications as a conversion cathode, engineering of hierarchical nanostructured FeOF coupled with conductive decoration is highly desired, yet rarely reported. Herein, 3D starfish-like FeOF on reduced graphene oxide sheets (FeOF/rGO) is successfully prepared, for the first time, through a combination of solvothermal reaction, self-assembly, and thermal reduction. Integrating the structural features of the 3D hierarchical nanostructure, which favorably shorten the path for electron/ion transport and alleviate volumetric changes, with those of graphene wrapping, which can further enhance the electrical conductivity and maintain the structural stability of the electrode, the as-prepared FeOF/rGO composite exhibits a superior lithium-storage performance, including a high reversible capacity (424.5 mA h⁻¹ g⁻¹ at 50 mA g⁻¹), excellent stability (0.016 % capacity decay per cycle during 180 cycles), and remarkable rate capability (275.8 mA h⁻¹ g⁻¹ at 2000 mA g⁻¹).     

Efficient Synthesis of Spirooxindole Pyrrolones by a Rhodium(III)‐Catalyzed C−H Activation/Carbene Insertion/Lossen Rearrangement Sequence

A rhodium(III)‐catalyzed domino annulation of simple olefins with diazo oxindoles to give spirooxindole pyrrolone products is described. This reaction can be formally viewed as the result of an anomalous tandem C?H activation, carbene insertion, Lossen rearrangement, and a nucleophilic addition process. The potential utility of this reaction was further demonstrated by the late‐stage diversification of drug molecules.     

黏弹细棒中直达波提取及其动态力学参数的宽频测试

黏弹性材料的动态力学参数可通过对材料样品中纵波测试并结合波速法计算得到。由于测试样品尺寸的限制,除了高损耗材料在高频范围外,不管是在样品端头或侧面都难以获得准确的直达波信号,导致参数测量不准确。针对这个问题,对一端固定一端自由的黏弹性细棒中的纵波传播过程进行了分析,提出了黏弹性细棒直达波提取的方法,并实现了黏弹性材料动态力学参数的宽频测试。采用宽带脉冲作为测试激励信号,利用两台激光测振仪对细棒的固定端和自由端的振动速度进行测试,计算得到细棒自由端处的直达波。然后,利用提取出的直达波信号进行波速法计算,得到了黏弹性细棒宽频范围内的储能模量和损耗因子,宽频脉冲测试结果与黏弹仪测试结果相吻合,验证了该方法的有效性。基于直达波提取的宽频测试方法不仅效率高,而且可以使波速法应用于更低的频段。     

Novel Dual‐Site‐Binding Neuraminidase Inhibitor from Virtual Screening by Pharmacophore and Molecular Dynamics Methods

Neuraminidase is a significant anti‐influenza target that plays crucial role in virus replication cycle. The discovery of 150‐cavity in Group‐1 neuraminidase provides us a novel mentality of designing inhibitor which can bind with both conserved site and 150‐cavity. In order to discover novel dual‐site‐binding inhibitors, a 3D chemical‐feature‐based pharmacophore model was established to cover dual‐site in neuraminidase. The dual‐site‐binding model was consistent in predicting the binding conformation of Group‐1 neuraminidase inhibitor and applied for virtual screening of Specs database. Compound 4 (ZINC05790048) that aligned well to the model was selected after multiple filtrations for molecular dynamics simulations, indicating improved binding energy with neuraminidase. It can sever as the lead compound for a novel series of inhibitors.     

The influence of Li sources on physical and electrochemical properties of LiNi<Subscript>0.5</Subscript>Mn<Subscript>1.5</Subscript>O<Subscript>4</Subscript> cathode materials for lithium-ion batteries

LiNi_0.5Mn_1.5O₄ cathode materials were successfully prepared by sol–gel method with two different Li sources. The effect of both lithium acetate and lithium hydroxide on physical and electrochemical performances of LiNi_0.5Mn_1.5O₄ was investigated by scanning electron microscopy, Fourier transform infrared, X-ray diffraction, and electrochemical method. The structure of both samples is confirmed as typical cubic spinel with Fd3m space group, whichever lithium salt is adopted. The grain size of LiNi_0.5Mn_1.5O₄ powder and its electrochemical behaviors are strongly affected by Li sources. For the samples prepared with lithium acetate, more spinel nucleation should form during the precalcination process, which was stimulated by the heat released from the combustion of extra organic acetate group. Therefore, the particle size of the obtained powder presents smaller average and wider distribution, which facilitates the initial discharge capacity and deteriorates the cycling performance. More seriously, there exists cation replacement of Li sites by transition metal elements, which causes channel block for Li ion transference and deteriorates the rate capability. The compound obtained with lithium hydroxide exhibits better electrochemical responses in terms of both cycling and rate properties due to higher crystallinity, moderate particle size, narrow size distribution and lower transition cation substitute content.     

Bessel identities in the waldspurger correspondence over the real numbers

We prove certain identities between Bessel functions attached to irreducible unitary representations ofPGL ₂(R) and Bessel functions attached to irreducible unitary representations of the double cover ofSL ₂(R). These identities give a correspondence between such representations which turns out to be the Waldspurger correspondence. In the process we prove several regularity theorems for Bessel distributions which appear in the relative trace formula. In the heart of the proof lies a classical result of Weber and Hardy on a Fourier transform of classical Bessel functions. This paper constitutes the local (real) spectral theory of the relative trace formula for the Waldspurger correspondence for which the global part was developed by Jacquet. Research of first author was partially supported by NSF grant DMS-0070762. Research of second author was partially supported by NSF grant DMS-9729992 and DMS 9971003.     

葡萄糖在KRPB生理缓冲溶液中电还原反应的研究

葡萄糖在ＫＲＰＢ生理缓冲溶液中电还原反应的研究朱庆存，姜力夫，郁章玉，陈常峰，周正宇（曲阜师范大学，电化学研究所，曲阜２７３１６５）关键词：葡萄糖，扩散系数，磷酸盐生理溶液。本文从葡萄糖在铂电极上的电氧化还原峰电流与ｐＨ值的线性关系，扩散系数与葡萄糖...     

Ultrafast Intercalation Enabled by Strong Solvent–Host Interactions: Understanding Solvent Effect at the Atomic Level

Solvents play an essential role in many areas of chemistry and is the cornerstone of understanding reactivity in solution‐phase reactions. Solvent effects have been widely observed in intercalation reactions; however, understanding of the influence of solvents on the thermodynamics and kinetics remains largely elusive in intercalation chemistry. Now, the solvent‐dependent kinetics of ferrocene intercalation into a layered vanadyl phosphate (VOPO₄?2 H₂O) host is presented, with a special focus on primary alcohols. From methanol to 1‐hexnaol, the intercalation rate peaks in 1‐propanol (80 times faster than the slowest case in methanol). Similar kinetics of exfoliation are also found in these solvents without ferrocene. The correlation between intercalation and exfoliation is understood at atomic level by DFT calculations, which reveal the role of pre‐intercalated solvent molecules play in intralayer interactions, interlayer expansion, and layer sliding.     

Surface-modified CdS quantum dots as luminescent probes for sulfadiazine determination

A novel, sensitive and convenient determine technology based on the quenching of the fluorescence intensity of functionalized CdS quantum dots by sulfadiazine was proposed. Luminescent CdS semiconductor quantum dots (QDs) modified by thioglycollic acid (TGA) were synthesized with the microwave method. The modified CdS QDs are water-soluble, stable and highly luminescent. The possible mechanism for the reaction was also discussed. When sulfadiazine was added into the CdS QDs colloid solution, the surface of CdS QDs generates the electrostatic interaction in aqueous medium, which induces the quenching of fluorescence emission at 489 nm. Under optimum condition, the fluorescence intensity versus sulfadiazine concentration gave a linear response according Stern-Volmer equation with an excellent 0.9981 correlation coefficient. The linearity range of the calibration curve was 1.2 x 10(-5) to 2.13 x 10(-3) mol L(-1). The limit of detection (3delta) is 8.0 micromol L(-1). The relative standard deviation for five determinations of 0.13 x 10(-3)mol L(-1) sulfadiazine is 1.4%. The concentrations of sulfadiazine injections were determined by the proposed method with a satisfactory result.     

Density functional theory study on the structure and vibrational frequencies of glycylglycine

Eleven possible conformers of glycylglycine have been studied by using the BLYP, B3LYP methods of density functional theory and the HF method at the basis set of 6-311++G**. BLYP (using Becke's and Lee-Yang-Parr's correlation functionals), ab initio Hartree-Fock (HF) and hybrid DFT/HF B3LYP calculations have been carried out to study the structure and vibrational spectra of glycylglycine. Glycylglycine crystal structure has been determined by X-ray diffraction analysis. The title compound has been crystallizes in the orthorhombic space group C1, with Z=4. And the unit cell parameters are: a=8.1184(12)A, b=9.5542(14)A, c=7.8192(11)A and V=577.95(15)A(3). Molecular conformation calculations have got 11 possible conformers. In these possible conformers, the most stable one has been selected. The BLYP/6-311++G** and scaled HF/6-311++G** frequencies correspond well with available experimental assignments of the normal vibrational modes. Comparison of the observed fundamental vibrational frequencies of glycylglycine and calculated results by density functional B3LYP and Hartree-Fock (HF) methods indicates that B3LYP is superior to the scaled Hartree-Fock (HF) for molecular vibrational issues.