An elementary proof for the representation theorem of analytic isotropic tensor functions of a second-order tensor

正following Cayley-Hamilton theorem:(1)where I1, I2, and I3denote the first, second, and third principal invariants of and N-dimensional space,(2)     

Grey system model with the fractional order accumulation

The perturbation theory of least squares method is applied to explain why the traditional accumulated generating operator violates the principle of new information priority of Grey system theory. A new Grey system model with the fractional order accumulation is put forward and the priority of new information can be better reflected when the accumulation order number becomes smaller in the in-sample model. But Grey system model cannot deal with the systems with memory when the accumulation order number is 0 in the in-sample model. The results of practical numerical examples demonstrate that the new Grey model provides very remarkable predication performance compared with the traditional Grey model for small sample.     

An anisotropic coarse‐grained model based on Gay–Berne and electric multipole potentials and its application to simulate a DMPC bilayer in an implicit solvent model

In this work, we aim at optimizing the performance of the anisotropic GBEMP model, which adopts a framework by combining a Gay–Berne (GB) anisotropic potential with an electric multipole (EMP) potential, in simulating a DMPC lipid bilayer in an implicit solvent model. First, the Gay–Berne parameters were initially obtained by fitting to atomistic profiles of van der Waals interactions between homodimers of molecular fragments while EMP parameters was directly derived from the expansion of point multipoles at predefined EMP sites. Second, the GB and EMP parameters for DMPC molecule were carefully optimized to be comparable to AMBER atomistic model in the calculations of the dipole moments of DMPC monomers adopting different conformations as well as the nonbonded interactions between two DMPC molecules adopting different conformations and separated at various distances. Finally, the GB parameters for DMPC were slightly adjusted in simulating a 72 DMPC bilayer system so that our GBEMP model would be able to reproduce a few important structural properties, namely, thickness (), area per lipid ( ) and volume per lipid ( ). Meanwhile, the atomistic and experimental results for electron density profiles and order parameters were reproduced reasonably well by the GBEMP model, demonstrating the promising feature of GBEMP model in modeling lipid systems. Finally, we have shown that current GBEMP model is more efficient by a factor of about 25 than AMBER atomistic point charge model. © 2015 Wiley Periodicals, Inc.     

羟基磷灰石作催化剂和催化剂载体的应用

羟基磷灰石(hydroxyapatite,HAP) 是一种微溶于水的弱碱性磷酸钙盐,由于其具有强吸附性、表面酸碱可调性和强离子交换性 (能与大多数金属离子发生离子交换)等特殊性质可作为催化剂或催化剂载体广泛应用于催化领域。本文综述了羟基磷灰石作为催化剂及催化剂载体在催化领域中的应用,重点综述了羟基磷灰石在氧化反应(醇的氧化、烃的脱氢反应)、还原反应(氢解与加氢)、C-C键的形成反应(Claisen-Schmidt缩合、Michael加成、Knoevenagel缩合、Friedel-Crafts反应、Diels-Alder和adol反应、Heck反应等)等领域的应用。     

钇铁氧体磁流体的超顺磁性研究

报道了用化学共沉淀法制备煤渍基钇铁氧体磁流体,并用Ｆａｒａｄａｙ式磁天平测定磁性胶体粒子在不同磁场强度和温度时的磁化率,根据Ｌａｎｇｅｖｉｎ函数,由σ－～Ｈ／Ｔ图证实了制备的磁流体具有超顺磁性,其闭锁温度在７７Ｋ～１４５Ｋ之间。此外,用ＴＥＭ、ＩＲ、ＸＲＤ、ＤＴＡ等分析测试手段对磁粒子的开头、大小和结 测定和分析。磁粒子的粒径在１５ｎｍ左右。     

液膜固定化细胞甾体转化的研究

本文研究了液膜固定化简单节杆菌进行较大有机分子甾体类的生物转化,结果表明液膜固定化细胞可成功进行氢化可的松→去氢氢化可的松的△′-脱氢反应。研究了液膜固定化细胞的制备、性质和影响甾体转化的各种因素。在某些液膜体系中其转化反应初期的比活力与自由细胞相同。细胞在液膜内可存活较长时间,提高了贮存稳定性。液膜固定化细胞体系基本不受染茵的影响,而自由细胞转化作用明显受抑制。     

Top electrode-dependent resistance switching behaviors of lanthanum-doped ZnO film memory devices

Lanthanum-doped ZnO (Zn_0.99La_0.01O) polycrystalline thin films were deposited on Pt/Ti/SiO₂/Si substrates by a chemical solution deposition method. Metal/La-doped ZnO/Pt sandwich structures were constructed by depositing different top electrodes (Ag and Pt). Unipolar switching and bipolar switching characteristics were investigated in Pt/La-doped ZnO/Pt and Ag/La-doped ZnO/Pt structures, respectively. Compared with the undoped devices (Pt/ZnO/Pt and Ag/ZnO/Pt), the La-doped devices exhibits superior resistive switching performances, such as narrow distribution of the resistive switching properties (R _ON, R _OFF, V _Set, and V _Reset), higher R _OFF/R _ON ratio and sharp switching transition.