Can Millimeter Waves Generate Electroporation?

Analysis of the field distributions in a single biological cell under electromagnetic wave is given. With Debye approximation, the dielectric relaxation of each part of the cell, including the extracellular and cellular media, the cell membrane and the nuclear membrane, was taken into account. Making use of some typical parameters for a cell, the voltage across nuclear and cytoplasma membranes under electromagnetic waves are calculated up to millimeter wave frequency range. The calculated result indicates that it is unlikely to generate electroporation by present available millimeter wave sources.     

利用微悬臂梁表面应力研究聚N-异丙基丙烯酰胺分子的构象转变

提出了一种基于微悬臂梁传感技术研究大分子折叠/构象转变的新方法.通过分子自组装的方法将热敏性的聚N-异丙基丙烯酰胺(PNIPAM)分子链修饰到微悬臂梁的单侧表面,用光杠杆技术检测温度在20-40 ℃之间变化时由于微悬臂梁上的PNIPAM分子在水中的构象转变所引起的微悬臂梁变形.实验结果显示:在升温过程中,微悬臂梁的表面应力发生了变化并且导致微悬臂梁产生了弯曲变形,这个过程对应着微悬臂梁上的PNIPAM分子从无规线团构象到塌缩小球构象的构象转变.在降温过程中,微悬臂梁发生了反方向的弯曲变形,这对应着PNIPAM分子从塌缩小球构象向无规线团构象的构象转变.整个温度变化过程中构象转变是连续进行的,而在低临界溶解温度(约32 ℃)附近转变幅度较大,这与自由水溶液中PNIPAM分子的无规线团-塌缩小球构象转变相对应.实验结果还显示:由于PNIPAM分子在塌缩过程中氢键的形成和链段间可能的缠结效应,整个温度循环过程中微悬臂梁的变形是不可逆的且有明显的迟滞效应.     

V3+:YAG晶体的生长、色心与光谱性能研究

采用石墨电阻加热的温梯法生长了V:YAG晶体,晶体的不同部位呈现两种不同的颜色:浅绿色和黄褐色.通过对比分析不同颜色V:YAG晶体的室温吸收光谱,推断出石墨发热体高温下扩散出来的C可以起到还原作用,提高晶体中V3+tetra离子的浓度,同时诱导了F心的形成.在1300℃下,对不同颜色的V:YAG晶体进行真空退火处理,发现处于八面体格位中的V3+离子在热激发作用下与近邻的四面体格位Al3+离子存在置换反应,由此产生一定浓度的四面体格位V3+离子.同时,F心在退火过程中被完全消除,释放出来的自由电子被高价态的V离子俘获,可以进一步提高晶体中四面体格位V3+离子的浓度.     

强流脉冲离子束辐照靶及其喷发的数值研究

利用拟合实测的TEMP Ⅱ型加速器磁绝缘二极管(MID)电压波形及其焦点附近束流密度曲线，建立了Gaussian分布模型，据此计算了与靶作用的离子的能量及数量，采用Monte Carlo(MC)方法计算了沉积在靶内的能量.并以此作为热源，与流体动力学(HD)模型相结合，对不同的靶状态采用相应的状态方程，模拟计算了靶内压力演化情况; 同时对烧蚀产生的等离子体采用理想气体状态方程, 结合HD方程组, 模拟计算了喷发过程中压力的空间演化过程. 关键词： 强流脉冲离子束 Gaussian模型 HD方程 数值研究     

Fe100-xPdx合金纳米线阵列的制备及其磁性研究

利用直流电沉积法在多孔阳极氧化铝模板中制备出了一系列Fe100-xPdx磁性纳米线阵列. Pd的增加使纳米线的总体磁性降低,各向异性和矫顽力也发生了较大的变化. 当Pd含量高达x=30时,纳米线仍有相当高的矫顽力(7.48 kA/m)和较明显的各向异性,但当Pd的含量增加到50%时,纳米线的易磁化方向由平行线的方向反转到垂直线的方向. 实验证明,这是由于在Fe80Pd20 和Fe70Pd30中连续的磁性相在Fe50Pd50纳米线中变成了与非磁性相相互间隔的非连续片状结构. 片状磁性相的形状各向异性使易磁化方向转变到垂直纳米线轴的方向. 从生长动力学的角度对Fe50Pd50纳米线中这种片状的形成进行了解释.     

聚丙烯孔洞铁电驻极体膜的电极化及其电荷动态特性

根据栅控恒压电晕充电组合反极性电晕补偿充电法的实验结果计算出铁电驻极体的极化强度.结果说明，伴随着薄膜内孔洞气体的Paschen击穿，该铁电体的极化强度随栅压增加而显著上升.利用上述充电方法和热刺激放电(TSD)谱的分析讨论了这类空间电荷型宏观电偶极子，及与其补偿的空间电荷热退极化的电荷动态特性；阐明了这两类俘获电荷的能阱分布，即构成宏观电偶极子的位于孔洞上下介质层内的等值异号空间电荷分别被俘获在深、浅两种能值陷阱内，而位于薄膜表面层的注入空间电荷则被俘获在中等能值陷阱中. 关键词： 反极性电晕补偿充电法 铁电驻极体 充电电流 热刺激放电     

空气/水界面水分子的取向和运动

对四种不同的实验构型下空气／水界面自由O-H键在3700cm~(-1)的和频振动光谱的分析表明,水分子在空气／水界面的取向运动只可能是在平衡位置附近有限角度之内的受限转动。界面水分子的自由O-H键取向距界面法线约33°,而取向分布或运动的宽度不超过15°。这一图像显著地不同于Wei等人(Phys. Rev. Lett.86,4799(2001))只通过单一的SFG实验构型所得出结论,即：空气／水界面的水分子在超快的振动弛豫时间内在很大的角度范围内运动。     

Growth studies of m-GaN layers on LiAlO2 by MOCVD

This paper reports that the m-plane GaN layer is grown on （200）-plane LiAlO2 substrate by metal-organic chemical wpour deposition （MOCVD） method. Tetragonal-shaped crystallites appear at the smooth surface. Raman measurement illuminates the compressive stress in the layer which is released with increasing the layer＇s thickness. The high transmittance （80%）, sharp band edge and excitonic absorption peak show that the GaN layer has good optical quality. The donor acceptor pair emission peak located at -3.41 eV with full-width at half maximum of 120 meV and no yellow peaks in the photoluminescence spectra partially show that no Li incorporated into GaN layer from the LiAlO2 substrate.     

Double-layer structural-acoustic coupling for cylindrical shell by using a combination of WDA and BIE

This work formulates the double-layer structural-acoustic coupling problem for cylindrical shell by using a combination of the wave-number domain approach (WDA) and the boundary integral equation (BIE). Expressions for the spectral radial velocity of the outer surface of a finite fluid-filled/submerged (FFS) cylindrical thin shell are formulated by means of the transfer matrix equation in wave-number domain. It is shown that the spectral variables on the inner surface of the shell are related to those on the outer surface of the shell. The far field sound radiation from this kind of shell is numerically evaluated for various fluid cases. An experimental verification is performed, and a good correlation between the theoretical results and the experimental results shows that the theoretical study work in this paper is correct.     

Nuclear Quadrupole Coupling Constants of Chlorine and Microwave Spectrum, Structure, and ab Initio Calculation of 1-Chloro-1,1,2-trifluoroethane

The microwave spectrum of the ³⁵Cl and ³⁷Cl isotopic species of 1-chloro-1,1,2-trifluoroethane (HCFC-133b) has been investigated in the frequency region 10 to 50 GHz using a Stark modulation microwave spectrometer. A pulsed jet Fourier transform microwave spectrometer was also used for the measurement of hyperfine splittings. A least-squares analysis of the observed b-type Q- and R-branch transition frequencies gave rotational and centrifugal distortion constants and components of the chlorine nuclear quadrupole coupling constant tensors in the principal axes system as follows: A=4625.161 (3) MHz, B=2004.127 (2) MHz, C=1875.813 (2) MHz, Δ_J=0.144 (9) kHz, Δ_JK=1.0748 (8) kHz, Δ_K=1.57 (1) kHz, δ_J=0.01376 (4) kHz, δ_K=−0.146 (4) kHz, χ_aa=−57.958 (10) MHz, χ_bb=21.231 (11) MHz, and χ_cc=36.727 (11) MHz for ³⁵ClCF₂CH₂F species, and A=4607.684 (6) MHz, B=1960.565 (2) MHz, C=1834.823 (2) MHz, Δ_J=0.106 (7) kHz, Δ_JK=1.022 (3) kHz, Δ_K=1.48 (1) kHz, δ_J=0.0142 (2) kHz, δ_K=−0.18 (2) kHz, χ_aa=−46.268 (11) MHz, χ_bb=17.319 (13) MHz, and χ_cc=28.950 (13) MHz for ³⁷ClCF₂CH₂F species. The structural parameters are calculated from the observed six rotational constants by assuming the partial structure of ab initio calculation. The electronic properties of the C-Cl bond are evaluated from the observed nuclear quadrupole constants of chlorine. These molecular properties are compared with those of other related molecules.