准粒子注入下超导膜能隙变化的一些计算

利用 Schn-Tremblay 理论计算了 Pb、Sn 超导薄膜在注入准粒子且注入电压很小(ev<2△(?))时的能隙微小增加的效应.同时,把此理论扩展到 ev>>2△_i 的大电压情况,计算出能隙明显减小及超导-正常混合态的结果.     

Effect of Torsion on Cisplatin-Induced DNA Condensation

We investigate the effect of torsion on DNA condensation with the covalently closed circular DNA as the torsionconstrained system, using an atomic force microscope. It is found that there are two stages in the DNA condensation process under torsional constraint. At the early stage, the low torsion will accelerate DNA condensation by promoting the formation of micro-loops or intersection structures; while at the later stage, the increasing torsion will slow it down by preventing the crosslinking of cisplatin and DNA since the DNA molecule becomes more rigid. Our results show the important role of torsion in DNA condensation and sheds new light on the mechanism for DNA condensation.     

家兔肠相关淋巴组织圆小囊超微结构观察

目的：揭示不同年龄家兔肠相关淋巴组织圆小囊的超微结构特点及其与肠道黏膜免疫的关系。方法：采用扫描电镜及透射电镜对2月龄，1年龄，2年龄兔圆小囊黏膜和黏膜下淋巴组织的结构进行观察，结果：与一般肠道淋巴组织比较，圆小囊的淋巴组织内细胞排列紧密，无间隙或间隙很小；细胞成份复杂多样，尤其在其淋巴组织中含有大量的神经内分泌细胞，还有多量上皮性网状细胞和树突状细胞，覆盖于淋巴组织表面的圆顶上皮中含有丰富的膜上皮细胞（microfold cell.M细胞），并常见肠道细菌附着于M细胞表面或被裹入其细胞内，结论：兔圆小囊与其他肠相关淋巴细胞（PP）的结构有明显不同。     

Investigation of the structural and dynamic basis of kinesin dissociation from microtubule by atomistic molecular dynamics simulations

Kinesin is a molecular motor that can step processively on microtubules via the hydrolysis of ATP molecules. An important factor characterizing the processivity of the kinesin motor is its dissociation from the microtubule. Here, using all-atom molecular dynamics simulations, we studied the dissociation process of the kinesin head in weak-microtubule-binding or ADP state from tubulin on the basis of the available high-resolution structural data for the head and tubulin. By analyzing the simulated snapshots of the structure of the head-tubulin complex we provided detailed structural and dynamic information for the dissociation process. We found that the dissociation of the head along different directions relative to the tubulin exhibits very different dynamic behaviors. Moreover, the potential forms or energy landscapes of the interaction between the head and tubulin along different directions were determined. The studies have important implications for the detailed molecular mechanism of the dissociation of the kinesin motor and thus are critical to the mechanism of its processivity.     

Effects of pH on Oxaliplatin-Induced Condensation of Single DNA Molecules

By using magnetic tweezers, atomic force microscope and mass spectrometry, we study the effects of pH on oxaliplatin-induced DNA condensation, the DNA persistence length, the amounts of micro-loops and of oxaliplatin bound to DNA. It is found that the DNA condensation degree, the amounts of micro-loops and of oxaliplatin bound to DNA increase with the decrease in the pH value while the DNA persistence length has an opposite behavior. The observed effects may be related to the drug resistance of cancer cells.