Vessel laser angioplastyin vitro

Summary This paper presents a set of measurements concerning the laser ability to perforate human atheromatic plaque and thrombus. Split segments of arteries were prepared under wet conditions and exposed to laser light at different power values and exposures. A multiline argon-ion laser, 5 W nominal power, coupled with a quartz fiber (600 μm diameter) was used. A dose effect correlation was found in the presence of homogeneous targets, independently of the power used. A linear fit to the data was made, which showed a very similar slope for homogeneous plaque (0.054±0.026, for a normalized χ²=0.08), as well as for organized thrombus (0.051±0.04, χ²=0.09). Such a correlation did not show up in the presence of nonhomogeneous targets.     

One-dimensional harmonic lattice caricature of hydrodynamics: Second approximation

The long-time behavior of an infinite chain of coupled harmonic oscillators is studied. In addition to a limiting hydrodynamic (Euler-type) equation, the next approximation is investigated. The corresponding equation is derived.     

A thermochemical instability. II. Inhomogeneous fluctuations

The behavior of coupled stochastic fields near a cusp bifurcation is studied. The results are applied to a thermochemical model and the possibility of observing nonclassical critidal behavior is discussed.     

直流外电场诱导的MgI高里德堡态的混合

在直流外电场存在时,观察到MgI的经双光子禁戒跃迁3s~2 ~1S→3mp ~(1P)的多光子电离和倍频效应并解释为外电场引起的里德堡(Rydberg)态之间轨道角动量的混合.实验结果与理论解释一致.     

组装L-B膜光学二次谐波的实验研究

一种分子形成的多层L-B膜由于相邻层的分子取向相反而使非线性极化抵消,总的X~(2)=0.本文用光学二次谐波方法确定了带有不同极性基团的L-B单分子层的有效非线性系数的大小和符号,对有效非线性系数符号相反的两种单分子层交替组装,使相邻单分子层的非线性极化相互叠加,得到了具有较大二阶非线性系数的组装L-B膜.     

激光加热微管靶反激光方向二次谐波时空分辨结构

本文报道了高功率激光加热微管靶,从入射激光的反方向观察二次谐波的时空分辨结构,分析了激光与微管靶的相互耦合过程.在激光与等离子体细丝相互作用的理论基础上,解释了微管区域内反激光方向二次谐波辐射的特殊现象.     

Second harmonic magnetoacoustic responses of magnetic nanoparticles in magnetoacoustic tomography with magnetic induction

Due to the unique magnetic, mechanical and thermal properties, magnetic nanoparticles(MNPs) have comprehensive applications as the contrast and therapeutic agents in biomedical imaging and magnetic hyperthermia. The linear and nonlinear magnetoacoustic responses determined by the magnetic properties of MNPs have attracted more and more attention in biomedical engineering. By considering the relaxation time of MNPs, we derive the formulae of second harmonic magnetoacoustic responses(2H-MARs) for a cylindrical MNP solution model based on the mechanical oscillations of MNPs in magnetoacoustic tomography with magnetic induction(MAT-MI). It is proved that only the second harmonic magnetoacoustic oscillations can be generated by MNPs under an alternating magnetic excitation. The acoustic pressure of the 2H-MAR is proportional to the square of the magnetic field intensity and exhibits a linear increase with the concentration of MNPs. Numerical simulations of the 2H-MAR are confirmed by the experimental measurements for various magnetic field intensities and solution concentrations using a laser vibrometer. The favorable results demonstrate the feasibility of the harmonic measurements without the fundamental interference of the electromagnetic excitation, and suggest a new harmonic imaging strategy of MAT-MI for MNPs with enhanced spatial resolution and improved signal-to-noise ratio in biomedical applications.     

注汽油井蒸气汽液比的折射率法测量研究

给油田的油井中注入高温高压蒸气时,从井口到井底连续地查明汽液比对节省能源和提高产出率意义重大。由于干蒸气和水的折射率不同,汽液的比例可以从汽液两相流的折射率响应特性反映出来。研制的测量装置采用蓝宝石作为折射率敏感的探测头,直接对汽液两相流的比例变化产生响应,能够应用于高温高压及狭窄工作空间的输汽环境中。装置在锅炉输汽管道中的实测响应曲线反映了输汽过程中汽液比的真实变化。该装置还在井深800m,井口蒸气温度270℃、压力10Mpa的油田注汽井中进行测量,测得的结果对注汽法采油的井况分析具有一定的作用。     

复合型变耦合系数定向耦合器开关特性的研究

研究了高斯—常数—高斯平滑连接的复合型变耦合系数定向耦合器的开关特性曲线。研究了耦合器各分段长度对开关曲线的影响。数值模拟发现,耦合器各组成部分的参量对耦合器开关曲线尾部的振荡及开关功率的大小均有影响,且呈现出一定的规律性。高斯型波导部分的相对长度以及直波导部分所占份额共同决定了耦合器开关曲线尾部的振荡大小,且开关曲线的振荡与耦合函数的傅里叶变换的振荡密切相关。