Prediction of interaction between small molecule and enzyme using AdaBoost

The knowledge of whether one enzyme can interact with a small molecule is essential for understanding the molecular and cellular functions of organisms. In this paper, we introduce a classifier to predict the small molecule– enzyme interaction, i.e., whether they can interact with each other. Small molecules are represented by their chemical functional groups, and enzymes are represented by their biochemical and physicochemical properties, resulting in a total of 160 features. These features are input into the AdaBoost classifier, which is known to have good generalization ability to predict interaction. As a result, the overall prediction accuracy, tested by tenfold cross-validation and independent sets, is 81.76% and 83.35%, respectively, suggesting that this strategy is effective. In this research, we typically choose interactions between small molecules and enzymes involved in metabolism to ultimately improve further understanding of metabolic pathways. An online predictor developed by this research is available at . Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Negative refractive index in chiral spiral metamaterials at terahertz frequencies

A three-dimensional chiral metamaterial consisting of arrays of the multi-layered mutually twisted metallic spirals is proposed. We theoretically demonstrate such a chiral spiral structure exhibiting negative refractive index at terahertz frequencies. The chirality with varied refractive index can be obtained by change of configurations of the structure. The presented design offers flexibility for investigation of electromagnetic properties of chiral metamaterials in the terahertz regime and thus leads to a unique route to terahertz device applications.     

Nonautonomous helical motion of magnetization in ferromagnetic nanowire driven by spin-polarized current and magnetic field

Under the generalized gradient approximation (GGA), the electronic and magnetic properties are studied for H-terminated zigzag edge Si nanoribbon (ZSiNR) decorated with a single C chain by using the first-principles projector augmented wave (PAW) potential within the density function theory (DFT) framework. The results show that either a perfect ZSiNR or a single C chain decorated ZSiNR, the ferromagnetic state is preferred over the antiferromagnetic state. But a single C chain decorated ZSiNR is more stable than the perfect one. Furthermore, the electronic and magnetic properties of a ZSiNR can be modulated in detail by a single C chain at different positions.     

Exact Analytical Solution to Equations of Perihelion Advance in General Relativity

Previously the perihelion advance in binary system was computed approximately. We will present an exact analytical solution to nonlinear differential equation of perihelion advance by method of Jacobian elliptic function and the advanced angle between successive perihelions. Project supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars from Ministry of Education, China (Grant No. [2004]527) and the Natural Science Foundation of Hunan Province, China (Grant No. 06JJ2026)     

The impact of stochastic lead time reduction on inventory cost under order crossover

We use exponential lead times to demonstrate that reducing mean lead time has a secondary reduction of the variance due to order crossover. The net effect is that of reducing the inventory cost, and if the reduction in inventory cost overrides the investment in lead time reduction, then the lead time reduction strategy would be tenable.We define lead time reduction as the process of decreasing lead time at an increased cost. To date, decreasing lead times has been confined to deterministic instances. We examine the case where lead times are exponential, for when lead times are stochastic, deliveries are subject to order crossover, so that we must consider effective lead times rather than the actual lead times. The result is that the variance of these lead times is less than the variance of the original replenishment lead times.Here we present a two-stage procedure for reducing the mean and variance for exponentially distributed lead times. We assume that the lead time is made of one or several components and is the time between when the need of a replenishment order is determined to the time of receipt.     

Crystal structure and the role of cation group factor in the third‐order nonlinear optical properties of cadmium complexes constructed by 1,3‐dithiole‐2‐thione‐4,5‐dithiolato ligand

A cadmium complex bis(benzyltriethylammonium) bis(1,3‐dithiole‐2‐thione‐4,5‐dithiolato)‐cadmium(II) ((TEBA)₂[Cd(DMIT)₂]) has been synthesized and its crystal structure has been determined by means of X‐ray single‐crystal diffraction. The central cadmium(II) ion coordinates with two DMIT, which constructed a distorted tetrahedron environment. Its third‐order nonlinear optical properties have been studied using Z‐scan technique with 20 ps pulses at wavelength 1064 nm. Its third‐order nonlinear susceptibility χ⁽³⁾ value was determined to be 1.24 × 10⁻¹⁹ m² V⁻², the figure of merit, χ⁽³⁾/α₀, was estimated to be 2.64 × 10⁻²⁰ m³ V⁻². Copyright © 2011 John Wiley & Sons, Ltd.