Nonlocal Galerkin Strip Transfer Function Method for Vibration of Double-Layered Graphene Mass Sensor

Double-layered graphene sheets(DLGSs) can be applied to the development of a new generation of nanomechanical sensors due to their unique physical properties. A rectangular DLGS with a nanoparticle randomly located in the upper sheet is modeled as two nonlocal Kirchhoff plates connected by van der Waals forces. The Galerkin strip transfer function method which is a semi-analytical method is developed to compute the natural frequencies of the massplate vibrating system. It can give exact closed-form solutions along the longitudinal direction of the strip. The results obtained from the semi-analytical method are compared with the previous ones, and the differences between the single-layered graphene sheet(SLGS) and the DLGS mass sensors are also investigated. The results demonstrate the similarity of the in-phase mode between the SLGS and DLGS mass sensors. The sensitivity of the DLGS mass sensor can be increased by decreasing the nonlocal parameter, moving the attached nanoparticle closer to the DLGS center and making the DLGS smaller. These conclusions are helpful for the design and application of graphene-sheet-based resonators as nano-mass sensors.     

Isatindolignanoside A,a glucosidic indole-lignan conjugate from an aqueous extract of the Isatis indigotica roots

A glucosidic indole-lignan conjugate with a novel carbon skeleton, named isatindolignanoside A (1), was isolated from an aqueous extract of the Isatis indigotica roots “ban lan gen”. Its structure was determined by comprehensive analysis of spectroscopic data, enzyme hydrolysis, and electronic CD calculations. Compound 1 is active against Coxsackie virus B3 and represents the first example of natural product having a structural feature of conjugation between indole and lignan, and its plausible biosynthetic pathway is postulated.     

Mott-Insulator-Superfluid Phase Transition with Coupled-Cavity Frequency Conversion System

An array of coupled cavities, each of which contains a triangle-down-level atom, is investigated. An effective Hamiltonian can be achieved under the strong classical driving. We can control the transition between Mott-insulator and superfluid states by the classical driving. The frequency conversion in one site has the same effects of nonlinear in BH hamiltonian which can induce insulator-superfluid states.     

Solid State Synthesis of Spinel-Type Metal Oxide Mg1.5Fe0.5MnO4 and Study of Its Exchange Capability for Li+

Russian Journal of Applied Chemistry - The spinel-type composite metal oxide, magnesium-manganese-titanium oxide (Mg1.5Fe0.5MnO4), was prepared by the method of solid state crystallization. As a...     

Activity Essential Residue Analysis of Taxoid 10β-O-Acetyl Transferase for Enzymatic Synthesis of Baccatin

Taxoid 10β-O-acetyl transferase (DBAT) is a key enzyme in the biosynthesis of the famous anticancer drug paclitaxel, which catalyses the formation of baccatin III from 10-deacetylbaccatin III (10-DAB). However, the activity essential residues of the enzyme are still unknown, and the acylation mechanism from its natural substrate 10-deacetylbaccatin III and acetyl CoA to baccatin III remains unclear. In this study, the homology modelling, molecular docking, site-directed mutagenesis, and kinetic parameter determination of the enzyme were carried out. The results showed that the enzyme mutant DBAT^H162A resulted in complete loss of enzymatic activity, suggesting that the residue histidine at 162 was essential to DBAT activity. Residues D166 and R363 which were located in the pocket of the enzyme by homology modelling and molecular docking were also important for DBAT activity through the site-directed mutations. Furthermore, four amino acid residues including S31 and D34 from motif SXXD, D372 and G376 from motif DFGWG also played important roles on acylation. This was the first report of the elucidation of the activity essential residues of DBAT, making it possible for the further structural-based re-design of the enzyme for efficient biotransformation of baccatin III and paclitaxel.     

弹性波通过一维复合材料系统的透射性质

提出了不同结构的一维弹性波复合材料系统模型,包括一维周期结构声子晶体、标准Fibonacci准周期结构声子晶体、广义Fibonacci准周期结构声子晶体以及完全无序结构的复合材料系统. 采用模式匹配理论法,数值计算了弹性波通过一维复合材料系统的透射系数. 计算结果表明,利用特殊的准周期结构声子晶体可获得比周期结构声子晶体更宽的带隙范围,准周期结构排列的复合材料系统相当于在周期结构中引入了缺陷体一样,带隙内出现了丰富的局域模式. 对弹性波/声波在复合材料系统中局域态性质的研究有助于弹性波/声波滤波器、导波器 关键词： 弹性波复合材料 局域化     

自旋阀中电流诱导磁化翻转行为的研究

通过实验研究了一种特殊的反对称自旋阀结构．研究发现,随着外加磁场的增大,该结构纳米器件表现出了一种由“逆CIMS”向“正常CIMS”的转变．这种现象是因为：该反对称自旋阀在不同的外加磁场下有不同的磁化取向,因而引起不同的CIMS行为． 关键词： CPP ESPV CIMS