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测试了PolyA,PolyU及其双链复合物Po1yA·PolyU的拉曼光谱,研究了双链形成前后的光谱变化.结果显示:(1)15℃下,在pH 7.0的0.14 mol.L-1 NaCl,1 mmol·L-1 Tris水溶液中,PolyU, PolyA,PolyA·PolyU分别以无规卷曲、A型单螺旋和A型双螺旋结构存在.后两种结构区别于前者的主 要光谱标志之一是有序结构在814 cm-1附近出现的拉曼峰.另一光谱标志则是1 100cm-1附近的谱峰半高宽的大小.PolyA,PolyA·PolyU在该处有着相同的半高宽,而PolyU在该处的谱峰则有明显的展宽.此外,还发现PolyA的有序程度不及PolyA·PolyU,这可以从(813±2)cm-1与1 100 cm-1的峰强比推知;(2)PolyU,PolyA形成双螺旋复合物之后,多聚核苷酸碱基-碱基堆积力大为增强,主链构象变得更为有序化,从而产生了明显的拉曼减色效应并伴随着相关谱带的频移.在这个过程中,PolyU链比PolyA链所产生的光谱变化更为显著.该研究表明,从这类实验结果中提取特征光谱标志有望实现基因芯片的拉曼光谱检测. 相似文献
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高质量三维光子晶体的实验制备及理论分析 总被引:2,自引:0,他引:2
对压强控制自组装法进行了改进,采用了密封硅胶颗粒的强吸水装置,为光子晶体样品的制备提供了一个稳定的温度、湿度和压强环境.将温度、压强分别控制在35 ℃、45 mmHg,利用直径为260 nm的聚苯乙烯胶体球进行了高质量三维光子晶体样品的制备.从理论计算和实验测量等方面对制备的光子晶体样品的结构、质量和性能进行了对比分析,结果表明,利用该实验装置进行光子晶体样品的制备时,可重复性高;制备的光子晶体样品具有较为完美有序的密堆结构,质量较好;在光子晶体样品的Г L方向有深且窄的光子带隙和陡峭的带隙边沿.光子带隙深度为83%,宽度为0.073,带隙边沿陡峭度为8%/nm,这为超快全光开关等先进的光学设备的研究奠定了基础. 相似文献
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高质量三维光子晶体的制备及其透射谱研究 总被引:3,自引:2,他引:1
设计了简易的压强可控自组装实验装置,制备了由直径为260 nm的聚苯乙烯(PS)胶体球组成的面心立方光子晶体.分析了压强的变化对光子禁带(PBG)深度及光子带隙边缘(PBE)坡度的影响,确定了合适的压强生长环境(P=5999.5 Pa).利用该实验装置,还进行了光子晶体的小批量制备,一次性制得了三块光子晶体,并从不同角度对每一块光子晶体的透射谱及不同光子晶体的透射谱进行了测量.同一光子晶体不同位置透射谱的重合、同一批次制备的不同光子晶体透射谱的一致性及光子禁带两侧的Fabry-Pérot振荡等均说明:该装置制备的光子晶体在大区域、大面积上是高度有序、均一和平整的;利用该实验装置进行光子晶体的小批量制备是可行的. 相似文献
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G-A mismatches are non-canonical base pairs that widely occur in native nucleic acids. They have been found to be functionally important in adopting unusual structures. In this paper, G-A mispairing was studied by Raman spectral characterization of Polyadenylic acid (PolyA), Polyguanylic acid (PolyG) and their equimolar mixture in solution of 0.08 mol/L Na^+, pH7.0. The experiment showed the following three results. (1) At the experimental conditions used in the present work, PolyA and G A complexes existed as single-stranded and double-stranded helix of A form, respectively. And PolyG mainly occurred to be anti-parallel quadruplex conformers. (2) The formation of G A complexes, on one hand strengthened parts of base stacking interactions especially for PolyG, leading to Raman hypochromism effect with some corresponding bands shifting, and on the other hand weakened other base stacking interactions especially for PolyA to a certain degree. During this process, the backbone of PolyG underwent a significant change, but PolyA still conserved its main chain conformation. (3) The formation of G A complexes was stabilized by two interbase hydrogen- bond interactions (i.e. N6H2(A)-N3 (G) and N7 (A)--N2H2(G)) and a third hydrogen bond between O2^+ (G) and N6 (A). The third hydrogen bond was responsible for the remarkable changes of PolyG backbone conformation.[第一段] 相似文献
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