Free vibrations of rectangular orthotropic shallow shells with varying thickness

The paper proposes a numerical-analytic approach to studying the free vibrations of orthotropic shallow shells with double curvature and rectangular planform. The approach is based on the spline-approximation of unknown functions. Calculations are carried out for different types of boundary conditions. The influence of the mid-surface curvature and variable thickness on the behavior of dynamic characteristics is studied __________ Translated from Prikladnaya Mekhanika, Vol. 43, No. 6, pp. 102–115, June 2007.     

Reflection of Pulse Waves and Resonance Characteristics of Arterial Beds

The problem of axisymmetric wave flow of a viscous incompressible fluid in a system consisting of a long thin deformable tube and a terminal element that determines the conditions of wave reflection at the tube end is analyzed. An expression for the input admittance of the system is obtained and the dependence of the admittance on the system parameters is investigated. The resonant frequencies at which the admittance amplitude has extrema are found and it is shown that at these frequencies the admittance variations with variation of the terminal-element parameters are maximal. The dependence of the resonant frequency on the tube length is investigated. Possible applications of the results obtained to the hydromechanical interpretation of a novel method of pulse diagnostics are discussed.     

A Lattice Boltzmann model with high Reynolds number in the presence of external forces to describe microfluidics

We present here a lattice Boltzmann model with high Reynolds number in the presence of external force fields to describe electrokinetic phenomena in microfluidics, by considering pressure as the only external force for liquid flow. Our results from a 9-bit square lattice Boltzmann model are in excellent agreement with experimental data in pressure-driven microchannel flow that could not be fully described by electrokinetic theory. The difference between the predicted and experimental Reynolds numbers from pressure gradients are well within 5%. Our results suggest that the lattice Boltzmann model described here is an effective computational tool to predict the more complex microfluidic systems that might be problematic using conventional methods.     

三点四针法小切口重睑术的临床应用

目的:探讨"三点四针法"小切口重睑成形术的临床应用效果。方法:采用"三点四针"小切口法,即将经典"三点式"重睑术中段切口延长至5mm,内、外段切口设计长度3mm,内外段切口各1针,中段切口缝合2针,使重睑线"黄金点"上形成2个点的牢固粘连。结果:116例受术者,115例重睑流畅自然。1例患者术后3个月内左侧重睑皱褶变浅,经原切口修复,效果满意。结论:"三点四针"重睑成形术,创伤小,恢复快,效果确切,操作简易,值得推广。     

LED点阵书写显示屏的设计

LED显示屏的设计硬件主要由STC89C58单片机最小系统、32×32的双色点阵显示阵列、光笔、按键、液晶显示屏等组成。双色点阵中的红色LED始终工作在微亮的扫描状态,STC89C58单片机利用自制的光笔中红外光电三极管检测光笔触及位置处红色LED灯的点亮,计算出光笔位置的行列坐标,并根据按键设置的不同工作模式控制LED显示,从而实现点亮、划亮、反显、清屏、笔画拖动、轮流显示等功能。显示屏能根据环境光强自动调节显示屏的显示亮度,当在设定时间内光笔未接触显示屏或按键未按下时关闭所有显示,并使系统进入休眠状态,减少电能消耗,当有按键按下时系统恢复运行。     

Synthesis, spectroscopic characterization, DFT studies and biological assays of a novel gold(I) complex with 2-mercaptothiazoline

A new gold(I) complex with 2-mercaptothiazoline (MTZ) with the coordination formula [AuCN(C₃H₅NS₂)] was synthesized and characterized by chemical and spectroscopic measurements, DFT studies and biological assays. Infrared (IR) and ¹H, ¹³C and ¹⁵N nuclear magnetic resonance (NMR) spectroscopic measurements indicate coordination of the ligand to gold(I) through the nitrogen atom. Studies based on DFT confirmed nitrogen coordination to gold(I) as a minimum of the potential energy surface with calculations of the hessians showing no imaginary frequencies. Thermal decomposition starts at temperatures near 160 °C, leading to the formation of Au⁰ as the final residue at 1000 °C. The gold(I) complex with 2-mercaptothiazoline (Au-MTZ) is soluble in dimethyl sulfoxide (DMSO), and is insoluble in water, methanol, ethanol, acetonitrile and hexane. The antibacterial activities of the Au-MTZ complex were evaluated by an antibiogram assay using the disc diffusion method. The compound showed an effective antibacterial activity against Staphylococcus aureus (Gram-positive) and Escherichia coli and Pseudomonas aeruginosa (Gram-negative) bacterial cells. Biological analysis for evaluation of the cytotoxic effect of the Au-MTZ complex was performed using HeLa cells derived from human cervical adenocarcinoma. The complex presented a potent cytotoxic activity, inducing 85% of cell death at a concentration of 2.0 μmol L⁻¹.     

Components of the Net Current in Differential Pulse Polarography. Part 2. Kinetics and Adsorption

Components of the net response in differential pulse polarography were studied theoretically, assuming gradually changing electrode rate constant or strength of the reactant adsorption. The difference between the maximum potential of the peak component and the half‐wave potential of the wave component appear as an important parameter. From its value, the electrode rate constant can be calculated even when the standard potential is not known. In a reversible process, effects of the reactant adsorption on the mentioned separation are less pronounced. The results were compared with experimentally obtained effects. For deeper insight into the applicability of this approach, additional experimentally obtained polarograms (that reflect different potential/timing parameters or changing character of the electrode process) should be studied in terms of their components.     

脉冲抽样法测量低频相位差

介绍了一种用脉冲抽样法测量低频相位差的技术。这种技术以可编程逻辑门阵列(FPGA)和单片机为核心,测量的精度达到0.1°。和传统的测相法比较,这种测量方法最大的优点是省去了大量的硬件电路,特别是省去了对速度和漂移特性要求苛刻的整形电路,也省去了鉴相电路、大小相角判别电路,只需增加一个抽样保持电路,给设计、调试带来了方便,而且,这种测量没有传统意义的幅相误差,给整机性能的稳定性和一致性带来了好处。