白云石精制液中不同离子对碳酸钙晶须的影响

以白云石精制液和二氧化碳为实验原料,采用气液接触法制备碳酸钙晶须。研究了杂质离子Mg²⁺、NH⁺₄和NO^-₃对碳酸钙晶须长径比和形貌的影响。采用扫描电镜(SEM)和X射线衍射仪(XRD)对样品的形貌和晶体结构进行表征。结果表明:NH⁺₄浓度在0.3 mol/L,Mg²⁺浓度在0.05 mol/L,NO^-₃浓度在0.2 mol/L的情况下碳酸钙晶须的形貌和长径比最佳,其中长径比最高可以达到25以上;最后再结合晶体生长理论,阐明了碳酸钙晶须的结晶过程和生长机理。     

中国力学学会学术大会'2005（CCTAM'2005)会议简介

1 会议概况由中国力学学会主办,中国力学学会和北京工业大学共同承办的“中国力学学会学术大会’2005”(Chinese Conference of Theoretical and Applied Mechanics-2005,CCTAM’2005)于2005年8月26～28日在北京召开。大会主席由中国力学学会理事长崔尔杰院士担任,副主席有程耿东、贺德馨、李家春、沈为平、苏先樾、王自强、吴有生、杨卫、卢振洋、张泽。     

浅海波导中简正波干涉特征频率增强

针对浅海波导中水平线列阵接收的低频宽带低信噪比信号,提出了一种利用多拍信号相干累加来提高干涉简正波特征频谱信噪比的方法。这种方法主要针对未知距离和声源形式的运动声源,对不同时刻（或接收距离）处阵列输出信号进行WARPING变换,基于干涉简正波特征频率不变性原理,通过距离和径向速度比值的搜索来使得不同时刻或距离处信号自相关函数WARPING变换后频谱具有近似相同的特征频率,进而通过相干累加来增强信号干涉简正波特征频率。仿真和海上实验数据分析均验证了方法的性能。     

Tissue level microstructure and mechanical properties of the femoral head in the proximal femur of fracture patients

This study aims to investigate the regional variations of trabecular morphological parameters and mechanical parameters of the femoral head,as well as to determine the relationship between trabecular morphological and mechanical parameters.Seven femoral heads from patients with fractured proximal femur were scanned using a micro-CT system.Each femoral head was divided into 12 sub-regions according to the trabecular orientation.One 125 mm~3 trabecular cubic model was reconstructed from each sub-region.A total of 81 trabecular models were reconstructed,except three destroyed sub-regions from two femoral heads during the surgery.Trabecular morphological parameters,i.e.trabecular separation(Tb.Sp),trabecular thickness(Tb.Th),specific bone surface(BS/B V),bone volume fraction(BV/TV),structural model index(SMI),and degree of anisotropy(DA) were measured.Micro-finite element analyses were performed for each cube to obtain the apparent Young's modulus and tissue level von Mises stress distribution under 1%compressive strain along three orthogonal directions,respectively.Results revealed significant regional variations in the morphological parameters(P0.05).Young's moduli along the trabecular orientation were significantly higher than those along the other two directions.In general,trabecular mechanical properties in the medial region were lower than those in the lateral region.Trabecular mechanical parameters along the trabecular orientation were significantly correlated with BS/BV,BV/TV,Tb.Th,and DA.In this study,regional variations of microstructural features and mechanical properties in the femoral head of patients with proximal femur fracture were thoroughly investigated at the tissue level.The results of this study will help to elucidate the mechanism of femoral head fracture for reducing fracture risk and developing treatment strategies for the elderly.     

基于点目标连通域标记的实时特征提取及其分布式运算

在高速运动目标的视觉测量中,高分辨率、高帧频的图像序列带来了大量待处理数据,如何快速地从这些数据中识别合作目标并提取其特征信息,成为高速视觉测量中的难题。对此,针对高速相机每个时钟周期多像素并行传输的数据特点,提出一种基于多维金字塔的硬件加速处理结构,实现连通域的全局搜索与标记,并根据标记结果完成对应特征的实时提取。在现场可编程逻辑门阵列中,通过金字塔结构的二维处理节点阵列与多标签特征统计的一维处理阵列,将数据流的高密度运算均衡分布于各运算节点,结合流水线并行,将视觉系统中占据较高耗时的全局搜索与标记过程在图像传输中同步实现。通过功能验证与实时性分析,该特征提取的分布式运算结构可在Camera Link接口85 MHz的时钟频率下,实现680 Mpixel/s的数据流实时处理,可作为预处理部分应用于高速视觉测量系统。     

Cascade syntheses of aza[2,1-b][1,3]-benzothiazinone heteropolycyclic compounds from cyclic thiourea catalyzed by Cu(I)

An efficient cascade method has been developed for the synthesis of aza[2,1-b][1,3]-benzothiazinones from cyclic thiourea and methyl 2-iodobenzoate via the Cu(I)-catalyzed C–S coupling/amidation process. A number of aza[2,1-b][1,3]-benzothiazinones containing five, six, seven membered rings and different substituents were obtained in good yield.     

Highly selective fluorescence turn-on determination of fluoride ions via chromogenic aggregation of a silyloxy-functionalized salicylaldehyde azine

A novel fluorescent chemsensor TBS-protected salicylaldehyde azine (TSAA) for fluoride ion was developed based on aggregation-induced emission (AIE). The probe TSAA was prepared by the reaction of salicylaldehyde azine (SAA) with tert-butyldimethylsilyl chloride (TBS-Cl) via an unusual synthetic methodology and shows only non-emission. Upon treatment with fluoride in aqueous MeCN solution, the TBS protective group of probe TSAA was removed readily and the fluorescence of the probe was switched on, which resulted in a new fluorescence peak around 543 nm. The fluorescent intensity at 543 nm increases linearly with fluoride ion concentration in the range 1–50 μmol L^?1. This proposed probe shows excellent selectivity toward fluoride ion over other common anions and cations.     

Metal-Free–Catalyzed Oxidative Trimerization of Indoles Using NaNO2 to Construct Quaternary Carbon Centers: Synthesis of 2-(1H-Indol-3-yl)-2,3′-biindolin-3-ones

A simple, convenient, and efficient synthesis of 2-(1H-indol-3-yl)-2,3′-biindolin-3-one derivatives via a transition-metal-free-catalyzed oxidative trimeric reaction of indoles has been developed. This transformation may have occurred through a tandem oxidative homocoupling reaction by using NaNO₂ in pyridine as oxidant. This methodology provides an alternative approach for the direct generation of all-carbon quaternary centers at the C2 position of indoles.     

基于R—K—F方法的模糊初值问题

本在Runge-Kutta-Fehlberg方法的基础上，运用模糊仿真的近似推理规则，讨论了当初始状态具有模糊不确定性时，求微分方程数值解的问题。