Typical Microstructures of Chinese Medicines with X-Ray Microscopy in Phase Contrast

Due to the low absorption contrast of plant tissues, traditional x-ray radiography has not been included in the microscopic techniques used in the identification of traditional Chinese medicines （TCMs）. With the development of x-ray phase contrast imaging （XPCI） in recent years, weakly absorbing materials could also be imaged by x- rays. Here we investigate microstructures of TCMs utilizing XPCI based on a nano-focus x-ray tube. The results demonstrated that XPCI is capable of revealing the microstructures of TCMs used as judging criteria in the identification of TCMs. The major advantages of the new method are nondestructivity, no special demand for sample preparation and suitability for thick samples.     

A convergence theorem for the Newton-like methods under some kind of weak Lipschitz conditions

We provide sufficient conditions for the convergence of the Newton-like methods in the assumption that the derivative satisfies some kind of weak Lipschitz conditions. Consequently, some important convergence theorems follow from our main result in this paper.     

STUDIES ON THE SYNTHESIS OF RABDOSIA DITERPENOID Ⅱ, PREPARATION OF A KEY BUILDING BLOCK, α, β-UNSATURATED LACTONE

The main half molecule (4a) of the trichorabdal B (1) was synthesized from pentadienol (6).The key step is the intramolecular Diels-Alder reaction of 8.     

Canon-π Interactions. Synthesis and Crystal Structure of Palladium Complex:[K(DB18C6)]_2[Pd(SCN)_4]

Noncovalentinteractionsplayadominantroleinmanyforefrontareasofmodemchemistry,frommat6rialsdesigntOmolecularbiology.Recelltly,theK -ninteractionshaveattractedmuchattentionbecauseoftheionseleCtivityinpotaSsiumchannelsl.Inothersystem,Sunneretal.showedthefirsttimebymassspectrometrythatK bindstobenzeneinthegasPhase:.ThisfindingstimulatedthestUdyoftheK -xinteractions.Indeed,theK -ninteractalshavealsobeen,identifiedbyX-raysinglecrystaldistractionanalysisforseveralcompouxtds:Km-be~usor--Phenyl',…     

Fluid forces on a square cylinder in oscillating flows with non‐zero‐mean velocities

The unsteady forces on a square cylinder in sinusoidally oscillating flows with non‐zero‐mean velocities are investigated numerically by using a weakly compressible‐flow method with three‐dimensional large eddy simulations. The major parameters in the analysis are Keulegan–Carpenter number (KC) and the ratio between the amplitude and the mean velocities of the approaching flow (A_R). By varying the values of KC and A_R the resulting drag and lift of the cylinders are analyzed systematically at two selected approaching‐flow attack angles (0 and 22.5^°). In the case of the non‐zero attack angle, results show that both the drag and lift histories can be adequately described by Morison equations. However, Morison equations fail to correctly describing the lift history as the attack angle is zero. In addition, when the ratio of A_R/KC is near the Strouhal number of the bluff‐body flow, the resulting drag is promoted due to the occurrence of resonance. Based on the results of systematic analyses, finally, the mean and inertia force coefficients at the two selected attack angles are presented as functions of KC and A_R based on the Morison relationships. Copyright © 2008 John Wiley & Sons, Ltd.     

抢渡长江最优路径的讨论

给出了2003年全国大学生数学建模竞赛D题的一种求解方法.运用拉格朗日乘数法与变分法建立了水速变化时最优路径适合的方程.特别针对问题4,当水流速度线性变化时,导出了求解最优解的函数方程.     

激光测距机主要参数校准测量不确定度分析

简述激光测距机主要参数校准装置的组成，通过对其主要参数(最大测程、最小测程、测距准确度、重复频率、束散角)的校准测量进行详细的不确定度分析，评价激光测距机主要参数校准装置的达标程度。     

（K1（x），K2（x））-有限伸张映射

该文首先给出(K1(x),K2(x))一有限伸张映射的定义,然后研究其自我提高的可积性性质.最后利用Caccioppoli型不等式得到可去奇异性结果.     

Pressure‐Induced Emission Enhancement of a Series of Dicyanovinyl‐Substituted Aromatics: Pressure Tuning of the Molecular Population with Different Conformations

A series of dicyanovinyl‐substituted aromatic compounds (Ar‐DCV; Ar=9‐anthracenyl, 1‐naphthyl, 1‐pyrenyl) with dual fluorescence are prepared, and their emission properties—when molecularly dispersed in a polymer medium—are investigated under pressure perturbation. The total emission intensity is enhanced drastically from ambient pressure up to 70 kbar. Emission 30–107 times more intense than that at ambient pressure is observed at higher pressure. In dual emission, the enhancement of the local excited state (LE state) is significantly different from that of the intramolecular charge‐transfer state (ICT state). The intensity of the ICT emission increases faster (30–370 times) than that of the LE emission (less than 20 times). In accordance with spectroscopic data, emission dynamics at different pressures, and computational studies on the molecular conformations of these compounds, a kinetic model is proposed to explain the effect of pressure on the emissive properties of the Ar‐DCV compounds from the point of view of pressure‐dependent populations of the species in the ground state.