毫米波辐射对细胞膜电位变化影响机理研究

用细胞膜电压荧光技术及荧光显微技术,研究了毫米波场辐射下悬液中K562细胞膜电压的变化。结果表明,在相同辐射条件下,不同细胞浓度组的K562细胞膜电压变化规律是不相同的。然后用场近似等效方法,建立了毫米波场辐射下,排列在平面上的悬液细胞膜电压计算模型。根据模型,计算了悬液中的细胞膜电压,用生物电磁学的观点,对实验现象的产生机理进行了探讨。     

薄膜SOI RESURF结构击穿电压分析

提出了基于二维Ｐｏｉｓｓｏｎ方程的薄膜ＳＯＩ降低表面电场（ＲＥＳＵＲＦ结构解析物理模型．并在该模型基础上,给出了一种分析薄膜ＳＯＩＲＥＳＵＲＦ结构击穿电压的方法．利用这一方法计算了漂移区长度较长的薄膜ＳＯＩＲＥＳＵＲＦ结构击穿电压与漂移区掺杂浓度的关系,并定量分析了场ＳｉＯ２界面电荷密度对击穿电压和漂移区临界掺杂浓度的影响．首次提出了临界场ＳｉＯ２界面电荷密度的概念,并研究了其与漂移区掺杂浓度的关系．而且计算结果与ＭＥＤＩＣＩ模拟结果符合得很好．这些为漂移区长度较长的薄膜ＳＯＩＲＥＳＵＲＦ结构击穿电压的优     

操纵对象的层状结构对光作用力影响的研究

由于可实现对生物样品的非接触、无损伤操纵及可进行微作用力、微小位移的定量测定等优点,光镊己引起人们的热切关注,并作为一种新兴的技术手段正日益广泛地在生物医学研究领域得到广泛应用．光作用力的理论分析与数值计算对光镊系统的建立及实验操作具有指导性的意义,因此人们对光作用力的理论进行了广泛的研究与讨论．出于定量计算的可行性考虑,以往对光作用力的计算均采用均匀介质球体来作为计算模型．但是在具体的实验中,操作对象,如象细胞这样的生物样品不是均匀球体,其中,细胞膜、细胞质及细胞核折射率有着较大差别．所以,针…     

平面结场板结构表面场分布的二维解析

提出了基于二维泊松方程解的平面结场板结构的二维表面电场解析物理模型.在该模型基础上,分析了衬底掺杂浓度、场板厚度和长度对二维表面场分布的影响.解析预言的场分布与击穿电压的计算结果与先前的数值分析基本符合.该模型为场板结构的优化设计提供了理论基础.     

平面结场板结构表面场分布的二维解析

提出了基于二维泊松方程解的平面结场板结构的二维表面电场解析物理模型 .在该模型基础上 ,分析了衬底掺杂浓度、场板厚度和长度对二维表面场分布的影响 .解析预言的场分布与击穿电压的计算结果与先前的数值分析基本符合 .该模型为场板结构的优化设计提供了理论基础     

单个浮置场限环终端结构击穿电压模型

基于B.J.Baliga的击穿电压理论,通过求解双边突变圆柱结的泊松方程,提出了单个浮置场限环终端结构的击穿电压解析模型.该模型计算结果与模拟结果的误差在±7%之内,具有精度高、应用范围广等特点,可以帮助设计者初步确定浮置场限环注入窗口大小及与主结的间距等关键参数.     

射频板条CO_2激光器并联谐振技术的研究

本文利用周期性网络模型计算了射频板条CO2激光器电极的纵向电压分布．探讨了并联谐振技术在板条器件中获得成功运用的原因．提出了利用并联谐振技术进一步提高电压分布均匀性的两个途径．     

固液混合火箭发动机尾焰的红外特性研究

针对固液混合火箭发动机中Al2O3颗粒运动的影响,对喷管的内流场和外流场进行了一体化数值仿真,得到了温度、压力、组分浓度以及粒子浓度等参数的分布。利用以最新的分子光谱数据库HITRAN和HITEMP为基础编写的逐线积分法计算了气体光谱吸收系数,采用米氏散射模型计算了固体粒子的辐射特性参数。利用基于有限体积法离散辐射传输方程的模型计算出了尾焰的红外辐射亮度。通过进一步求解,得到了特定波段的光谱辐射强度。在8—14岬波段,利用红外热像仪进行了试验,并将试验结果与数值计算结果进行了比较。结果表明,该计算模型和方法能较好地模拟固液混合火箭发动机尾焰的红外辐射特性。     

不同的辐照方法对钴^60辐照红细胞的损伤

目的：评估不同的辐照方法对MAP保存液中红细胞造成的影响及存储损伤。方法：将滤除白细胞的红细胞悬液分三组．对照组不予辐照,即刻辐照组在采集后立刻辐照,14日辐照组在保存14日后进行辐照。在储存期的1、7、14、21、28、35天检测三组红细胞钾离子浓度、平均细胞体积及红细胞刚性指数,结果：辐照前14日辐照组刚性指数升高缓慢,辐照后升高加速,但至第35天时仍低于即刻辐照组。这种变化规律同样可以见于MCV与钾离子浓度检测。结论：血站发血前辐照红细胞悬液的方法是合理的。     

表面铺展技术在联会复合体电镜研究中的应用

本文较详细地介绍了本室改进的表面铺层－硝酸银染色制备联会复合体（SC）电镜样品技术。取小鼠睾丸组织制成细胞悬液，取少量悬液滴在0．4％KCl液珠表面上以通过表面张力使SC铺展开，用涂有Formvar膜的载玻片蘸取细胞，干燥后用多聚甲醛固定，硝酸银染色，光镜下找到要观察的细胞，然后转移到50目铜网上，电镜下既可看到整个SC核,,地可观察同源染色体的联会过程，SC的超微结构及各种类型的SC畸变，该技术可广泛应用于细胞遗传学，遗传毒理学，生殖生物学等诸多学科。     

Dependence of induced transmembrane potential on cell density,arrangement, and cell position inside a cell system

A nonuniform transmembrane potential (TMP) is induced on a cell membrane exposed to external electric field. If the induced TMP is above the threshold value, cell membrane becomes permeabilized in a reversible process called electropermeabilization. Studying electric potential distribution on the cell membrane gives us an insight into the effects of the electric field on cells and tissues. Since cells are always surrounded by other cells, we studied how their interactions influence the induced TMP. In the first part of our study, we studied dependence of potential distribution on cell arrangement and density in infinite cell suspensions where cells were organized into simple-cubic, body-centered cubic, and face-centered cubic lattice. In the second part of the study, we examined how induced TMP on a cell membrane is dependent on its position inside a three-dimensional cell cluster. Finally, the results for cells inside the cluster were compared to those in infinite lattice. We used numerical analysis for the study, specifically the finite-element method (FEM). The results for infinite cell suspensions show that the induced TMP depends on both: cell volume fraction and cell arrangement. We established from the results for finite volume cell clusters and layers, that there is no radial dependence of induced TMP for cells inside the cluster.     

AFM观察稳恒磁场对细胞表面精细结构的影响

利用原子力显微镜(AFM)观察稳恒磁场(SMF)处理后,悬浮生长细胞(K562人白血病细胞)、贴壁生长细胞(人结肠癌SW480细胞)、小鼠肝癌细胞Hepal-6和原代小鼠肝细胞表面精细结构的变化,以了解SMF杀伤肿瘤细胞的可能机制.观察结果显示:随曝磁时间延长,SMF可在肿瘤细胞表面造成不同程度损伤,主要表现为细胞膜上出现许多大小不一的凹陷,且凹陷数量和直径随着曝磁时间延长而增加.与MTT检测相比,AFM观察到的各类细胞表面损伤远早于细胞的生长抑制.实验观察显示,悬浮生长细胞比贴壁生长细胞对磁场处理更为敏感,小鼠肝癌细胞比肝细胞对磁处理更敏感.实验结果显示,AFM能够及早观察到细胞表面因SMF作用而产生的精细结构方面的变化.     

AC losses in HTS tapes in applied longitudinal magnetic fields at variable temperatures

In most power devices, the conductor is carrying an ac transport current while it is exposed to an ac magnetic field transverse to the current path. In certain applications, such as power cables or a control winding in a controllable reactor, the conductors are exposed to a magnetic field component longitudinal to the tape axis that is parallel to the current path. To create an improved base for the design of such power devices it is of interest to study the losses in high-temperature superconductor tapes due to longitudinal field in detail. We have investigated the losses at several temperatures of a nontwisted multifilamentary Bi-2223 tape when it was exposed to a longitudinal magnetic field. The losses were measured with a calorimetric method and the results were compared with the critical state hysteresis loss model. The hysteresis losses are dominating at power frequencies (50, 60 Hz) in the investigated field range 2-200 mT and are accurately described by the critical state hysteresis model.     

Theoretical and experimental analysis of electroporated membrane conductance in cell suspension

An intense electric field can be applied to increase the membrane conductance G(m) and consequently, the conductivity of cell suspension. This phenomenon is called electroporation. This mechanism is used in a wide range of medical applications, genetic engineering, and therapies. Conductivity measurements of cell suspensions were carried out during application of electric fields from 40 to 165 kV/m. Experimental results were analyzed with two electroporation models: the asymptotic electroporation model was used to estimate G(m) at the beginning and at the end of electric field pulse, and the extended Kinosita electroporation model to increase G(m) linearly in time. The maximum G(m) was 1-7 × 10(4) S/m(2), and the critical angle (when the G(m) is insignificant) was 50°-65°. In addition, the sensitivity of electroporated membrane conductance to extracellular and cytoplasmatic conductivity and cell radius has been studied. This study showed that external conductivity and cell radius are important parameters affecting the pore-opening phenomenon. However, if the cell radius is larger than 7 μm in low conductivity medium, the cell dimensions are not so important.     

Second-order model of membrane electric field induced by alternating external electric fields

With biological cells exposed to ac electric fields below 100 kHz, external field is amplified in the cell membrane by a factor of several thousands (low-frequency plateau), while above 100 kHz, this amplification gradually decreases with frequency. Below 10 MHz, this situation is well described by the established first-order theory which treats the cytoplasm and the external medium as pure conductors. At higher frequencies, capacitive properties of the cytoplasm and the external medium become increasingly important and thus must be accounted for. This leads to a broader, second-order model, which is treated in detail in this paper. Unlike the first-order model, this model shows that above 10 MHz, the membrane field amplification stops decreasing and levels off again in the range of tens (high-frequency plateau). Existence of the high-frequency plateau could have an important impact on present theories of high-frequency electric fields effects on cells and their membranes.     

Computational analysis of the refractive index of multiple quantum wells for QWSC applications

In this paper, the authors extend on previous work regarding a new approach to calculating the refractive index of the quantum wells of a quantum well solar cell device. The new approach is computational and considers the presence of an electric field perpendicular to the quantum well layers. The model is based on the modified single effective oscillator (MSEO) model. The MSEO model is dependent upon three specific parametric equations. Using the relationships between these equations and how electric field effects these three parameters. The effects of the electric field on the refractive index of the quantum well layer can be determined. Computational analysis under AM 1.5 conditions for a hypothetical quantum well structure is performed with any discrepancies in the approach discussed.     

Ultrashort electrical pulses open a new gateway into biological cells

An electrical model for biological cells predicts that for pulses with durations shorter than the charging time of the outer membrane, there is an increasing probability of electric field interactions with intracellular structures. Experimental studies in which human cells were exposed to pulsed electric fields of up to 300-kV/cm amplitude, with durations as short as 10 ns, have confirmed this hypothesis. The observed effects include the breaching of intracellular granule membranes without permanent damage to the cell membrane, abrupt rises in intracellular free calcium levels, and enhanced expression of genes. At increased electric fields, the application of submicrosecond pulses induces apoptosis (programmed cell death) in biological cells, an effect that has been shown to reduce the growth of tumors. Possible applications of the intracellular electroeffect are enhancing gene delivery to the nucleus, controlling cell functions that depend on calcium release (causing cell immobilization), and treating tumors.     

多导体传输线瞬态响应研究

针对多导体传输线瞬态响应的无源性问题,提出了基于集总等效源模型的多导体传输线瞬态响应模型. 从外场激励下的多导体传输线的频域电报方程解出发,将外场在传输线上激励的分布电压源和电流源与传输线指数矩阵解耦,建立了集总等效电压源和电流源模型. 为避免复杂的傅里叶反变换及卷积运算,推导了集总源模型的时域递推方程. 在此基础上,采用时域有限差分法建立了端接线性负载、非线性负载和外场激励下的不等长多导体传输线瞬态响应离散递推方程. 通过对无损传输线的仿真对比,验证了方法的有效性. 最后,对端接线性负载、非线性负载和外场激励下的不等长多导体传输线瞬态响应进行了试验和仿真分析.       

Electrofluorescent colloid light switch

A low field electro-optic light switch mechanism is proposed, based on changes in the fluorescence from dye molecules absorbed to sepiolite clay particles. When tagged with acridine orange and suitably oriented in an electric field, sepiolite suspensions give fluorescence effects orders of magnitude greater than those for dye-tagged liquid crystals. Uses of the system are discussed.     

水平链路激光广播技术的功率传输方法与验证

当前传统点对点激光通信技术已经得到了长足进步,为了探索在有限范围内实现局域激光广播的有效手段,提出了一种适用于短距离水平链路激光广播的有效方法,设计了相应的验证性广播通信系统,并在光功率最优分配的角度上对激光广播进行了系统建模研究。首先,从光功率衰减的角度对激光扩束理论模型和平行光幕理论模型进行了分析和对比,揭示了平行光幕通信模型的光功率损失模型;其次,结合高斯光束光学成像变换理论模拟了平行光幕的远场场强分布情况,通过一个领先的光学和照明设计软件,揭示了光幕远场分布与传输距离的关系;最后,通过在不同信道环境下的野外通信实验验证了平行光幕理论模型的优越性与可行性。