X射线和~(60)Coγ射线辐照食管癌细胞的拉曼光谱研究

食管癌细胞(EC9706)经不同剂量X射线和60Coγ射线辐照后继续培养24h,利用激光拉曼光谱分析EC9706细胞内部蛋白质、核酸、脂类等生物大分子的构象和含量变化。分析发现,两种放射源各剂量组拉曼光谱的峰强和频移与空白对照组之间都存在较大的差异。主要表现为(1)X射线辐照后,对照组光谱中存在的某些谱带,个别剂量组中该谱带却消失。蛋白质主链中骨架C-N振动引起的1114 cm-1谱带在各剂量组中普遍消失,膜脂中膜结合β-胡萝卜素的C=C振动谱带1523 cm-1仅存在于6Gy组。(2)60Coγ射线辐照后,蛋白质酰胺Ⅲ带在中等剂量(4、5Gy)组中β折叠结构向无规卷曲转化,大剂量组中DNA中的磷酸二酯(O-P-O)基团的非氢键化程度增强。拉曼特征峰在不同剂量组中的变化,为进一步从物理能级结构角度研究X射线和60Coγ射线对EC9706细胞的辐照损伤机制提供了实验依据。     

脉冲微波对雄性大鼠生殖系统及其子代的影响

采用2.71GHz脉冲微波(脉冲场强为48kV/m,脉宽为750ns,脉冲个数分别为200个×1次、200个×10次、200个×20次)辐照SD雄性大鼠和孕鼠,利用流式细胞术、计算机辅助精子分析系统及水迷宫实验分别检测了精子发生过程中生精细胞DNA损伤情况、附睾内精子活力参数变化及子代学习记忆功能。结果表明:2.71GHz脉冲微波单次辐照会对雄性大鼠的生精过程产生一定的影响,但对附睾内精子质量无明显影响,而多次辐照对精子质量的影响具有累积效应;亲代大鼠在受照后,其子代的生长在短期会受阻,且学习、记忆能力也会受到一定的影响。     

拉曼光谱法研究不同环境温度下脉冲电场对胰岛素二级结构影响及理论模型分析

近年来,弱电磁辐射生物效应已受到人们的普遍关注.前期研究发现脉冲电场与环境温度对胰岛素分子的构象产生协同效应.因此,文章首先应用拉曼光谱法研究了不同环境温度下脉冲电场对胰岛素分子二级结构的影响,得到胰岛素分子α螺旋结构含量的变化;并运用蛋白质螺旋-线团结构转变模型对实验结果进行定量分析,得到的理论模型可以较好地刻画不同环境温度下,脉冲电场对胰岛素分子α螺旋结构含量的影响.脉冲电场的作用及热力学环境的改变,使蛋白质螺旋结构向无规线团结构发生转变,可以解释脉冲电场作用下,胰岛素分子α螺旋结构含量随环境温度升高而下降的原因.研究结果为进一步研究弱电磁辐射对生物大分子二级结构的非热效应机理提供了一定的实验依据及理论参考.     

X波段微波辐照致心肌损伤及机理研究

 采用90 W/cm² X波段微波全身一次辐照大鼠10 min，分别于辐照后0，0.5，1，3，6，12，24 h断头处死，取左心室心肌组织，光镜观察心肌组织形态学损伤；TUNEL法检测心肌组织细胞凋亡；RT-PCR检测大鼠心肌组织GSK3β，caspase-9和caspase-3 mRNA表达水平的变化；Western-blot法检测大鼠心肌组织GSK3β蛋白质磷酸化表达水平的变化；Caspase-9分析试剂盒检测心肌组织中caspase-9酶活性。研究结果表明：90 W/cm² X波段微波辐照可上调心肌组织GSK3β基因表达，使其蛋白磷酸化水平降低，解除了磷酸化对其活性的抑制，使GSK3β活性增强，从而参与了X波段微波辐照致心肌细胞凋亡的启动。90 W/cm² X波段微波辐照同时可使大鼠心肌组织中的凋亡相关蛋白激酶caspase-9和caspase-3基因表达上调，caspase-9酶活性增强，从而造成大鼠心肌细胞凋亡过程的启动，因此，GSK-3β及其下游介导的与凋亡相关的信号分子caspase-9和caspase-3的激活可能是X波段微波辐照致大鼠心肌细胞凋亡的重要途径之一。     

高功率微波辐照对雄性大鼠生殖细胞的影响

 采用激光扫描共聚焦显微镜观察受不同参数高功率微波辐照后的大鼠精子细胞内Ca²⁺的变化，同时观察了辐照后大鼠的生殖细胞微核率、畸形率、精子数量、存活率和顶体酶反应的变化。实验表明：此条件下的高功率微波辐照对雄性大鼠的生殖细胞微核率和畸形率没有明显的损伤效应，但4×10⁵次脉冲的高功率微波辐照对大鼠的顶体酶反应有较明显的抑制作用，可能通过改变细胞内第二信使的Ca²⁺浓度来影响其生殖细胞功能。     

镍、镉对生物膜损伤机理的FTIR研究

本文采用傅里叶变换红外（FTIR）漫反射光谱技术，研究比较了镍与镉对人类红细胞膜的联合损伤作用，同时对其作用机制进行了探讨。通过观察分析两金属与红细胞膜作用前后细胞膜红外光谱中1742、1662、1636、1556、1464、1405和1389cm-1等吸收峰的变化，表明两金属离子单独或同时存在均可使膜蛋白质发生变性和不可逆聚合、使膜脂质发生相变以及可能的重金属离子与蛋白质分子中-COOH侧链成盐等分子改变。实验还表明镍、镉对细胞膜的作用机制是类似的，联合作用时两金属离子可能协同引起细胞膜的损伤。     

真空环境中紫外脉冲激光对熔石英抗损伤能力的影响

在10-3Pa的高真空环境下,利用355nm的紫外脉冲激光以低于石英基片零概率损伤阈值的能量密度对其进行重复多次的全口径扫描,目的是为了研究石英基片在接受不同剂量的紫外激光辐照后其抗损伤能力的变化和原因.通过辐照过程中损伤点的扩展程度以及辐照后的抗损伤测量表明,高真空环境下紫外脉冲激光辐照后的石英基片抗损伤能力明显降低,降低的幅度更多的与其接受激光辐照的次数有关,辐照能量密度的影响相对较小;通过荧光及X射线光电子能谱(XPS)检测发现,紫外脉冲激光辐照后石英基片表面氧缺位的增加是导致其抗损伤能力下降的主要原因,其程度也直接与接受辐照的紫外脉冲激光剂量相关.     

荧光偏振法研究脉冲电场对酿酒酵母细胞膜流动性影响

以DPH(1,6-二苯基-1,3,5-己三烯)为荧光探剂,采用荧光偏振法探讨了脉冲电场(0～25kV.cm-1,0～266ms)对酿酒酵母细胞膜流动性影响。经5kV.cm-1电场处理后,酿酒酵母细胞膜的流动性显著减小,并且随电场强度和处理时间的增加而减小;通过平板计数法和紫外分光光度计法分别检测了脉冲电场对酿酒酵母细胞存活对数及膜通透性影响。结果显示,5kV.cm-1虽然只能使少量的酵母致死,却能使酵母细胞膜的通透性显著增加,膜流动性显著降低。并且细胞的存活率随电场强度增大而减小,细胞膜的通透性随电场强度增大而增大。这表明细胞膜的流动性降低与细胞膜的通透性升高成正相关,与细胞的存活率成负相关。由此推测脉冲电场在对酿酒酵母灭菌过程中,细胞膜是其作用的一个关键位点,膜流动性减小,细胞膜通透性增强,是细胞死亡的主要原因。     

应用圆二色光谱研究交变应力对烟草细胞膜蛋白结构的影响

本文用圆二色光谱(CD)研究了交变应力对烟草细胞膜蛋白结构的影响 采用本实验室研制的强声波发生装置来产生交变应力场,研究了不同强度和频率的交变应力场作用后烟草细胞膜蛋白结构的变化 研究结果表明:细胞膜蛋白结构变化与应力的频率和强度密切相关,一定频率和强度范围内的交变应力能使得烟草细胞膜蛋白的二级结构发生明显的变化,表现为α螺旋的增加和 β转角的减少 这反映了细胞膜蛋白和磷脂相互作用的增强和细胞膜流动性的增加,进而为细胞的生长和分裂提供有利的条件 从细胞和分子水平研究交变应力对植物生长、发育的影响及其作用机制是一个很有意义的尝试.     

变温红外光谱研究表面双稳态液晶分子的相变过程

运用变温红外和样本-样本相关光谱对40～150℃温度区间内的表面双稳态液晶分子MHOCPOOB的相变过程中的分子构象、排布及相互作用的变化进行研究.结果表明:室温时,分子烷基链中同时存在Zigzag和Gauche两种构象.随温度升高,其中有序的Zigzag构象转化为无序的Gauche构象,链的扭曲程度增加.刚性核部分,羰基与相邻的苯环形成共轭体系,苯环之间相互倾斜排列,在相变过程中羰基与苯环的共平面作用逐渐被打破,且在相变点苯环间的二面角明显增大.由于表面稳定化的作用,使得在液晶盒表面上的一层膜,其结构并不随温度、相结构的变化而变化,因而在液晶盒的光谱中观察到的相变点较少.通过二维光谱作者发现,在122℃时分子出现细微结构调整.     

微波辐照对胶原蛋白三股螺旋结构的影响

胶原蛋白的三股螺旋结构是其不同于其他蛋白质的特殊结构，也是其具有特殊功能的基础，然而，胶原的三股螺旋结构易在外界条件的影响下被破坏。目前微波已被越来越多的应用于胶原蛋白的提取和改性过程，但是关于微波辐照对胶原蛋白结构影响的研究还相对较少。首先从牛跟腱中提取胶原蛋白，然后采用0.5 mg·mL-1的胶原蛋白溶液在30 ℃下以微波辐照保温为实验样，水浴加热和未经加热处理为对比样，最后采用紫外-可见光谱、傅里叶变换红外光谱、圆二色谱以及荧光发射光谱等方法，对不同加热方法中胶原蛋白的三股螺旋结构和超分子结构进行表征，研究了微波辐照对胶原蛋白结构的影响。实验结果表明，在低于胶原变性温度的条件下，无论是微波辐照还是水浴加热都不会破坏胶原蛋白的三股螺旋结构，也不会使胶原蛋白变性。但是，与水浴加热相比，微波辐照会对胶原蛋白的聚集行为产生抑制作用。微波辐照对胶原蛋白的作用既有与常规加热相同的热效应，又有常规加热过程中不存在的非热效应，非热效应表现为抑制胶原蛋白的聚集行为。研究结果可为微波场中胶原蛋白结构和性质的变化提供科学依据。     

用傅里叶变换红外光谱研究增强UV-B辐射对PSⅡ蛋白结构的影响

运用傅里叶变换红外光谱技术研究了增强紫外线-B(UV-B)辐射对植物光系统Ⅱ(PSⅡ)中膜蛋白结构的影响.结果显示在增强的UV-B辐射条件下,PSⅡ中蛋白的α-螺旋、β-折叠强度增加,而β-转角的强度下降了近一倍,并且这些结构与周围的耦合减弱.此外,UV-B辐射使酪氨酸残基苯酚环的结构发生改变,并使其微极性降低.UV-...     

傅里叶变换显微红外光谱法研究羟自由基与红细胞膜脂和膜蛋 …

利用傅里叶变换显微红外光谱法和计算机辅助解析法研究了羟自由基作用于红细胞后膜蛋白二级结构的变化规律及羟自由基对红细胞膜脂质损伤的作用机理。结果表明，由于羟自由基的攻击，导致表征蛋白质二级结构的α－螺旋的含量发生变化；自由基损伤３０分钟后，放置３小时其蛋白结构仍不能恢复；     

Real-time Thermal Imaging of Microwave Accelerated Metal-Enhanced Fluorescence (MAMEF) Based Assays on Sapphire Plates

In this paper, we describe an optical geometry that facilitates our further characterization of the temperature changes above silver island films (SiFs) on sapphire plates, when exposed to microwave radiation. Since sapphire transmits IR, we designed an optical scheme to capture real-time temperature images of a thin water film on sapphire plates with and without SiFs during the application of a short microwave pulse. Using this optical scheme, we can accurately determine the temperature profile of solvents in proximity to metal structures when exposed to microwave irradiation. We believe that this optical scheme will provide us with a basis for further studies in designing metal structures to further improve plasmonic-fluorescence clinical sensing applications, such as those used in microwave accelerated metal-enhanced fluorescence (MAMEF).     

High-field DNP and ENDOR with a novel multiple-frequency resonance structure.

We describe a new triply tuned (e(-), (1)H, and (13)C) resonance structure operating at an electron Larmor frequency of 139.5 GHz for dynamic nuclear polarization (DNP) and electron nuclear double-resonance (ENDOR) experiments. In contrast to conventional double-resonance structures, the body of the microwave cavity simultaneously acts as a NMR coil, allowing for increased efficiency of radiofrequency irradiation while maintaining a high quality factor for microwave irradiation. The resonator design is ideal for low-gamma-nuclei ENDOR, where sensitivity is limited by the fact that electron spin relaxation times are on the order of the RF pulse lengths. The performance is demonstrated with (2)H ENDOR on a standard perdeuterated bis-diphenylene-phenyl-allyl stable radical. In DNP experiments, we show that the use of this resonator, combined with a low microwave power setup (17 mW), leads to significantly higher (1)H signal enhancement (epsilon approximately 400 +/- 50) than previously achieved at 5-T fields. The results emphasize the importance of optimizing the microwave B(1) field by improving either the quality factor of the microwave resonator or the microwave power level.     

Gene delivery process in a single animal cell after femtosecond laser microinjection

Microinjection of extracellular molecules into a single animal cell was performed by an amplified femtosecond laser irradiation. When a single-shot laser pulse was focused on the plasma membrane of a single fibroblast from the mouse cell line NIH3T3 with a high-numerical aperture objective lens, a transient hole with a diameter of 1 μm was formed. The delivery process of extracellular molecules immediately after the hole formation was monitored by a fluorescence staining with fluoresceinisothiocyanate-dextran (FITC-dextran). Then the gene expression was confirmed using a DNA plasmid of an enhanced green fluorescent protein (EGFP). The gene expression was observed when the laser pulse was focused first on the cellular membrane and then on the nuclear membrane, while the gene was not expressed when the laser was focused only on the cellular membrane. On the basis of these results, the efficiency of gene delivery by the femtosecond laser microinjection and the subsequent gene expression were clarified.     

Electromagnetic simulation study of dielectric wall accelerator structures

Two types of dielectric wall accelerator (DWA) structures, a bi-polar Blumlein line and zero integral pulse line (ZIP) structures were investigated. The high gradient insulator simulated by the particle in cell code con rms that it has little in uence on the axial electric field. The results of simulations using CST microwave studio indicate how the axial electric field is formed, and the electric eld waveforms agree with the theoretical one very well. The in uence of layer-to-layer coupling in a ZIP structure is much smaller and the electric eld waveform is much better. The axial of the Blumlein structure's electric field has better axial stability. From both of the above, it found that for a shorter pulse width, the axial electric field is much higher and the pulse stability and delity are much better. The CST simulation is very helpful for designing DWA structures.     

Ultrasound combined with slightly acidic electrolyzed water thawing of mutton: Effects on physicochemical properties,oxidation and structure of myofibrillar protein

The effects of air thawing (AT), water immersion thawing (WT), microwave thawing (MT) and ultrasound combined with slightly acidic electrolyzed water thawing (UST) on the myofibrillar protein (MP) properties (surface hydrophobicity, solubility, turbidity, particle size and zeta potential), protein oxidation (carbonyl content and sulfhydryl content) and structure (primary, secondary and tertiary) of frozen mutton were investigated in comparison with fresh mutton (FM). The solubility and turbidity results showed that the MP properties were significantly improved in the UST treatment. UST treatment could effectively reduce the MP aggregation and enhance the stability, which was similar to the FM. In addition, UST treatment could effectively inhibit protein oxidation during thawing as well. The primary structure of MP was not damaged by the thawing methods. UST treatment could reduce the damage to MP secondary and tertiary structure during the thawing process compared to other thawing methods. Overall, the UST treatment had a positive influence in maintaining the MP properties by inhibiting protein oxidation and protecting protein structure.     

FTIR analysis of protein secondary structure in cheddar cheese during ripening

Proteolysis is one of the most important biochemical reactions during cheese ripening. Studies on the secondary structure of proteins during ripening would be helpful for characterizing protein changes for assessing cheese quality. Fourier transform infrared spectroscopy (FTIR), with self-deconvolution, second derivative analysis and band curve-fitting, was used to characterize the secondary structure of proteins in Cheddar cheese during ripening. The spectra of the amide I region showed great similarity, while the relative contents of the secondary structures underwent a series of changes. As ripening progressed, the alpha-helix content decreased and the beta-sheet content increased. This structural shift was attributed to the strengthening of hydrogen bonds that resulted from hydrolysis of caseins. In summary, FTIR could provide the basis for rapid characterization of cheese that is undergoing ripening.     

基于二维相关红外光谱的鱼糜品质检测可行性分析

对二维相关光谱在鱼糜品质检测中的可行性进行了分析。利用二维相关技术结合中红外光谱技术对冻融处理后白鲢鱼糜蛋白二级结构变化进行了分析。在冻融次数和温度双重外扰的作用下对样品进行了分析。以冻融次数为外扰的二维相关光谱分析结果揭示了鱼糜蛋白二级结构的变化顺序： α-螺旋结构、分子内聚集的β-折叠结构→反平行的β-折叠结构→羰基结构；基于温度外扰的二维相关光谱分析结果表明： 冻融处理1次和2次后鱼糜蛋白二级结构变化轻微。而冻融处理3次之后鱼糜蛋白二级结构已遭到严重破坏。结果分析还发现： 外扰温度为45℃时，温度对羰基的影响比大大小于冻融循环对鱼糜蛋白二级结构的影响。以上结果说明二维相关光谱技术可以探测并直观的反应出鱼糜蛋白二级结构变化程度。如果能将这种变化程度量化，则可以利用该技术对鱼糜新鲜度等品质进行快速检测。