New,Non‐quinone Fluorogeldanamycin Derivatives Strongly Inhibit Hsp90

Streptomyces hygroscopicus is a natural producer of geldanamycin. Mutasynthetic supplementation of an AHBA‐blocked mutant with all possible monofluoro 3‐aminobenzoic acids provided new fluorogeldanamycins. These showed strong antiproliferative activity and inhibitory effects on human heat shock protein Hsp90. Binding to Hsp90 in the low nanomolar range was determined from molecular modelling, AFM analysis and by calorimetric studies.     

Structurally Diverse Polyamines: Solid‐Phase Synthesis and Interaction with DNA

A versatile solid‐phase approach based on peptide chemistry was used to construct four classes of structurally diverse polyamines with modified backbones: linear, partially constrained, branched, and cyclic. Their effects on DNA duplex stability and structure were examined. The polyamines showed distinct activities, thus highlighting the importance of polyamine backbone structure. Interestingly, the rank order of polyamine ability for DNA compaction was different to that for their effects on circular dichroism and melting temperature, thus indicating that these polyamines have distinct effects on secondary and higher‐order structures of DNA.     

抗体阻断表面黏附分子DNAM-1和LFA-1对人自然杀伤细胞肿瘤杀伤活性的抑制作用

目的探讨抗体阻断表面黏附分子DNAM-1和LFA-1对体外扩增的人自然杀伤(Natural killer,NK)细胞的肿瘤杀伤活性的影响。方法体外活化人外周血单个核细胞来源的NK细胞,并检测其表面黏附分子DNAM-1和LFA-1的表达水平;通过Trans-well阻隔试验,阻断NK细胞与靶细胞接触,考察细胞-细胞直接接触对NK细胞杀伤活性的影响;通过NK细胞毒性试验,引入抗DNAM-1单克隆抗体和抗LFA-1单克隆抗体,阻断相应信号途径,考察相关黏附分子在NK细胞肿瘤杀伤过程中的作用。结果体外活化的NK细胞高表达表面黏附分子DNAM-1和LFA-1。阻断NK细胞与靶细胞接触,NK细胞的肿瘤杀伤效应大大降低。应用单克隆抗体阻断DNAM-1或LFA-1信号途径,可显著降低NK细胞肿瘤的杀伤效应;联合阻断DNAM-1和LFA-1信号途径,可进一步降低NK的细胞杀伤效应。结论细胞-细胞间直接接触是NK细胞发挥肿瘤杀伤效应的重要机制,表面黏附分子DNAM-1和LFA-1介导的信号途径对维持NK细胞肿瘤杀伤活性具有重要意义。     

高分子量谷蛋白亚基近等基因系面粉品质及其流变学特性的研究

分析了高分子量谷蛋白亚基近等基因系的高分子量谷蛋白亚基组成，并对该近等基因系进行了品质性状的分析，结果表明：Glu-D1位点的变化比Glu-B1位点的变化对面粉品质和流变学特性影响大；并且同时具有Glu-B1 14 15和Glu-D1 5 10的近等基因系2号无论是面粉品质还是流变学特性都优于其它两个近等基因系8号(null，7 9，5 10)和近等基因系13号(null，14 15，10)；而8号又优于13号，即Glu-B1 14 15的存在没有弥补Glu-D1 5亚基的缺失。     

胶辊胶圈弹性与纺纱质量探讨

通过对胶辊，胶圈弹性的理论阐述，分析了在生产过程中胶辊胶圈弹性变化的作用及影响，说明了纺纱过程中胶辊胶圈弹性作用的具体特点，指出了在纺纱过程中保持胶辊胶圈弹性的稳定和提高是保证棉纱质量稳定的关键。     

合成红色绿柱石中通道水分子构型及1H和23Na核磁共振谱表征

以水热法合成贫碱型红色绿柱石和天然富碱、贫碱型绿柱石为研究对象, 采用VU, IR, NMR测试方法, 重点对绿柱石中通道水分子的构型及与钠离子的耦合关系进行研究. 结果表明, 贫碱型水热法合成红色绿柱石中Ⅰ型和Ⅱ型通道水分子并存, 但以Ⅰ型通道水分子的丰度明显占优. 合成红色绿柱石的1H NMR谱属典型的两自旋系, 分属两个独立的共振信号. 中心共振谱峰(δ=1.7×10-6)与Be-OH-Al有关, 为Ⅰ型通道水分子的表征. 伴生共振谱峰(δ=4.9×10-6)与H-O…Na有关, 代表Ⅱ型通道水分子. 23Na NMR谱中心线的化学位移随通道中Na离子浓度的增大而发生有规律的变化, 表现为23Na的共振谱峰自高场区向低场区偏移, 分裂强度增大, 裂距和半峰宽减小. 同时, 1H NMR的峰形自双自旋系向单自旋系转化. 证实合成红色绿柱石中通道水分子与碱金属离子之间存在明显的耦合关系.     

Hydrogen atom absorption in hydrogen-covered Pd(110) (1 × 2) missing-row surface

The absorption of H atom in H-covered Pd(110) (1 × 2) missing-row surface is investigated using density functional theory based calculations. For 1.5 monolayer H coverage, interaction among the adsorbed H atoms is found to be negligible and was verified by analyzing the electronic structure of the system and by comparing the calculated binding energies with low H coverage case. Neither the monoatomic absorption of H nor the assistance from the initially adsorbed H atom explains the experimentally observed presence of subsurface H in Pd(110) at high H coverage. Instead, H absorption is realized through the assistance of incoming H atoms from vacuum. The absorption of H in the H-covered surface is non-activated while the dissociation of H₂ is the rate-limiting process. Dissociation on ridge site is energetically more preferred than on trough site and the difference in the activation barrier is elucidated by investigating the electronic structures of the system.     

The reaction thermodynamics of hydrogen sulfide decomposition into hydrogen and diatomic sulfur

To verify a hypothesis about the electronic state of diatomic gaseous sulfur formed during the low-temperature catalytic decomposition of hydrogen sulfide, we carried out some experiments to examine elemental sulfur dissociation. As shown, after heating at ～1000?K, elemental sulfur sealed in quartz ampoules with metal catalysts followed by quenching at room temperature did not produce any visible changes on solid sulfur. However, conversion of solid sulfur into gaseous diatomic sulfur can be realized via intermediate interaction of melted sulfur with hydrogen in the presence of Pt followed by decomposition of H₂S formed on the surface of the metal catalyst at room temperature. It is suggested that the conversion of the singlet sulfur atoms into the ground triplet state becomes feasible only on the surface of metal catalysts resulted from the dissociation of hydrogen sulfide into adsorbed atomic species.     

近场光学显微探针技术

讨论了近来年近场光学显微探针技术的一些发展，重点介绍了原子量级的两类探针：单分子探针和单离子探针。     

VDC－MA悬浮共聚树脂分子量及其分布的研究

联用宽分布ＶＤＣ－ＭＡ悬浮共聚物试样的［η］和ＧＰＣ谱图数据，确定了此共聚物在四氢呋喃溶剂中、３０℃下的Ｍａｒｋ－Ｈｏｕｗｉｎｋ常数：Ｋ＝２．５４×１０－２，α＝０．６７５７。进一步研究了单体配比、转化率、引发剂浓度以及聚合温度等因素对于分子量及其分布的影响，并建立了分子量模型。