基于ANSYS的供电频率对高温超导直线感应电机性能影响的分析

通过对高温超导直线电机的理论分析,从内部电磁场的角度出发,研究供电频率的变化对高温超导直线电机的各项电磁性能影响。利用ANSYS有限元分析软件对电机的电磁场、电磁推力以及热损耗进行仿真,并对仿真结果进行简要说明。文中的研究结果对高温超导直线感应电机的运行参数设计提供了理论依据和分析基础。     

10年来我国电离辐射和电磁生物技术的农业应用研究与发展

统计１９８４－１９９３年间我国电离辐射和电磁生物技术在中农业中应用研究的文献量，并对这此文献进行了时间分布、空间分布、主题内容分布的分析研究，旨在从文献量及文献研究内容的角度探讨１０年来我国电离辐射和电磁生物技术的农业应用研究的状况与规律，为促进业新技术的应用和农业生产的发展提供依据。     

时域全波电磁计算程序JEMS-FDTD在复杂电磁环境研究中的应用

将自主研发的大规模并行三维全波电磁场时域求解程序JEMS-FDTD应用于复杂电磁环境问题,计算并分析了楼宇内电波传播特性和飞行器瞬态电磁特性。对楼宇内电波传播特性的计算获得了建筑物内任意位置的电磁场分布和电磁脉冲在建筑物内的时域传播过程,其结果可用于无线通信和电磁环境安全研究;对飞行器瞬态电磁特性的计算获得了飞行器舱内外瞬态电磁近场分布,其结果可用于飞行器强辐射场防护等研究。     

电磁AB效应与描述电磁场的基本物理量

本文通过介质电磁AB效应及其实验验证，论述了描述电磁场的基本物理量应为规范条件约束下的电磁势（φ，A），而不是场量（E，B）。     

电磁成形的物理学原理

本文从物理学的角度介绍了在塑性成形工业中的一种新工艺－－电磁盛开有的基本原理及技术方法。     

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分析了电磁波以任意角度入射到有限磁场中的激光等离子体通道天线(LPCA)时的电磁散射特性。根据LPCA的工作原理建立了其电磁分析模型,推导出广义柱坐标系下各向异性磁化等离子体中纵向分量所满足的波动方程和纵向场与横向场的关系,得到LPCA和周围媒质中的电磁场,利用边界切向电磁场连续,得出了散射系数方程。通过计算实例,将结果与文献结果比较,吻合较好。该研究结果预期可应用于高功率微波武器系统的研究。     

运动Dyon粒子双矢势场方程的格林函数解

首先回顾了有磁荷(或等效磁荷)存在的情况下电磁场双四维势的描述方法，给出了场强与双四维势的关系以及具有电磁对偶对称性的Maxwell方程；利用Green函数法求出了场方程具有Lorentz变换协变性的推迟解；最后给出了广义李纳-魏谢尔势的表述形式.     

从不变量看电磁场

本文从电磁场不变量的角度，考察电磁场，并与时－空间隔不变量类比，达到和谐统一的认识高度。     

空间对称性与电磁角动量守恒

阐明空间对称性与守恒律，并结合电磁场中带电粒子的拉氏函数，巧妙简捷地处理了一个电磁系统的角动量守恒。     

雷达波吸收剂的包覆改性设计

从电磁场理论出发，建立了包覆改性吸收剂等效电磁参数模型，初步得到了磁性吸收剂经介电改性后外包覆层和内层材料相对体积分数对损耗性能和特性阻抗的影响规律；以此为基础，进行了包覆改性吸收剂的结构设计；采用溶胶-凝胶法制备了包覆改性吸收剂，实验测试了样品的电磁参数，同理论预测结果进行了比较，表明理论预测的电磁参数频谱特性同实际测试结果比较接近. 关键词： 包覆改性吸收剂 等效电磁参数     

Theoretical Study on Effects of Salt and Temperature on Denaturation Transition of Double-stranded DNA

We investigate the statistical mechanics properties of a nonlinear dynamics model of the denaturation of the DNA double-helix and study the effects of salt concentration and temperature on denaturation transition of DNA. The specific heat, entropy, and denaturation temperature of the system versus salt concentration are obtained. These results show that the denaturation of DNA not only depends on the temperature but also is influenced by the salt concentration in the solution of DNA, which are in agreement with experimental measurement.     

High Pressure/Thermal Treatments Effects on Functionality of Comminuted Muscle from Different Meat Species

This paper analyses the response of comminuted meat from different species (pork, chicken, turkey and ostrich) to heating (45 and 70 °C/30 min) under pressure (400 MPa) condition. The results (protein solubility, thermal analysis and rheological properties) indicate that the effect of temperature on protein denaturation is reduced if heating takes place at high pressure; then, the pressurization process partially preserves the protein from thermal denaturation. They also show that it is the processing conditions rather than the species that modulate protein thermal stability.     

MOLECULAR MORPHOLOGY AND CRYSTALLIZATION IN THE QUANTUM LIMIT

The effects of phonons on crystallization and crystal morphology are investigated. It is shown that the commensuration of the lattice vibrations with the lattice will favor certain crystal morphologies. Vibrational effects can also be important for the molecular structure of chain molecules. In this case, the contribution from quantum mode forces to denaturation is estimated by using a simple phenomenological model describing the molecule as a continuum. The frequencies of the vibrational modes depend on the molecular dimensionality; hence, the zero-point energies for the folded and the denatured protein are estimated to differ by several electron volts. For a biomolecule, such energy is significant and may contribute to cold denaturing as seen for proteins. This is consistent with the empirical observation that cold denaturation is exothermic and hot denaturation endothermic.     

圆二色谱表征芥蓝抗坏血酸过氧化物酶变性过程中的结构变化

圆二色谱(CD)是一种特殊的吸收光谱,蛋白质的二级结构如α-螺旋、β-折叠、β-转角在远紫外区(190～250 nm)都具有特征性的CD图谱。为了了解芥蓝抗坏血酸过氧化物酶(BaAPX)在变性过程中活性变化和结构变化的关系,动态监测了不同时间、温度及浓度条件下BaAPX的比酶活及远紫外CD图谱,并利用CD分析软件Dichroweb计算了BaAPX中四种二级结构的百分含量。结果表明：BaAPX属于全α型蛋白,α-螺旋的百分含量与比酶活之间存在比较明显的正相关关系。在低浓度低温的变性过程中,BaAPX发生了初始态(N态)→α-螺旋最少态(R态)一步结构变化;在高浓度低温的变性过程中,BaAPX发生了N态→平衡态(T态)一步结构变化;在热处理后低温复性的变性过程中,BaAPX发生了N态→R态→T态两步结构变化。     

光谱法研究变性剂对苦荞麦蛋白质构象的影响

采用紫外差示光谱和荧光光谱研究了不同浓度的乙醇溶液和盐酸胍溶液对苦荞麦蛋白质(TBWSP31)构象变化的影响.研究表明,TBWSP31的色氨酸残基和酪氨酸残基有的位于分子内部,有的暴露于分子表面.乙醇溶液使TBWSP31变性时,仅仅是分子的外层结构发生了变化,分子内部疏水核的变化较小,高浓度的盐酸胍使位于TBWSP31...     

Protein dynamics in Brillouin light scattering: Termal denaturation of hen egg white lysozyme

Thermal denaturation of hen egg white lysozyme has been investigated by Brillouin light scattering in the temperature range from 297 to 350 K. Anomalies in the temperature dependences of velocity and damping of hypersound and also in the behavior of the intensity of Brillouin components for the lysozyme solution at thermal denaturation have been revealed. These anomalies are attributable to phase transformations of the protein in the high-temperature region. It has been shown that Brillouin light scattering is a suitable tool for studying the structural evolution of proteins.     

Laser correlation spectroscopy of the processes of serum albumin denaturation

Denaturation of serum albumin under the influence of temperature and ionic detergent sodium dodecylsulfate (SDS) is investigated by laser correlation spectroscopy of scattered light. It is shown that thermal denaturation is stronger at pH values of the buffer solution of protein that are close to the isoelectric point of the given protein. Coupling of the micelles of SDS with albumin follows the principle of positive cooperativity. The concentration of protein saturation with the surfactant is determined, upon the attainment of which further protein denaturation was not observed. It is shown that the interaction of SDS with albumin is of an electrostatic nature.Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 71, No. 6, pp. 831–835, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

A Nuclear Magnetic Resonance study of the reversible denaturation of hydrated lysozyme

The understanding of the physical processes that occur below the threshold of protein thermal denaturation is of fundamental importance. In this thermal region proteins undergo a reversible folding/unfolding process whose evolution depends upon temperature and time. When the kinetics of the folding is altered, the specific biological activity of the protein is altered as well and aggregation phenomena usually intervene. The most important role in driving these processes is played by the solvent and water is certainly the solvent par excellence. It is well known that proteins become biologically active with no less than a water monolayer covering their surface. The knowledge of the physical properties of this monolayer is of basic importance to prevent folding alterations. We present a proton Nuclear Magnetic Resonance study at very high resolution of the thermodynamic properties of lysozyme hydration water as a function of temperature and time in the thermal region of the reversible denaturation.     

DNA melting induced by alcohols: Role of the solvent properties

Summary The isothermal denaturation of calf thymus DNA, induced by the presence of some monohydric alcohols in the solution, was investigated. Measurements were performed at a temperature (67.2°C) at which the denaturation, in the absence of alcohols, is about 20% and melting profiles at varying temperatures were also recorded. Results show that with increasing alcohol concentration and alkyl group size DNA denaturation first reaches a maximum and then falls back. This behaviour, ascribed to ?unusual? water properties as inferred also from compressibility measurements, indicates that hydrophobic and electrostatic effects are connected in a complex way. Partially supported by Consiglio Nazionale delle Ricerche, Italy.     

ATR-FTIR分析冻结—解冻后的牛肉蛋白二级结构变化

研究了牛肉蛋白质二级结构稳定性在-18,-23及-38 ℃不同温度下的变化情况,明确了肉品工业中不同冷冻温度对肉品品质的作用机制。利用了傅里叶变换衰减全反射红外光谱(attenuated total reflectance Fourier transfer infrared spectroscopy,ATR-FTIR)技术、自动去卷积以及曲线拟合等计算方法,分析了-18,-23及-38 ℃三个温度下,牛肉肌原纤维蛋白(myofibrillar protein,MP)在冻结—解冻过程中的红外光谱图变化及蛋白质二级结构变性程度。ATR-FTIR结果显示,冻结—解冻过程中牛肉MP红外光谱图峰高、峰面积发生变化,且峰波数发生红移或者蓝移;冻结—解冻后牛肉MP红外光谱图中3 500～3 300 cm-1波段的吸收峰强度减弱甚至消失,说明解冻后牛肉MP中的结合水中O—H基团与氨基酸CO基团形成的分子内和分子间氢键断裂;冻结会影响牛肉MP二级结构的稳定性,导致牛肉蛋白质二级结构发生变化,其中除了无规则卷曲比例上升以外,α-螺旋、β-折叠、β-转角含量均下降,造成有序结构向无序结构转变;解冻后,冻结温度为-38 ℃的处理组牛肉β-折叠增加量大于-23和-18 ℃处理组,-38 ℃冻结牛肉MP二级结构的稳定性最好,解冻后蛋白质复性也最好。即蛋白质冷冻变性程度随着冻结温度的降低而减轻,蛋白质二级结构特征保持也越好。该试验研究基于肉品工业生产实际,研究结果从微观层面揭示了冻结温度对牛肉蛋白质变性的影响规律及可能的机制,为冷冻肉冻藏保鲜工艺制定提供了参考。