Bis-p-xylyl[26]crown-6/pyridinium ion recognition: one-pot synthesis of molecular shuttles

Simple one-pot syntheses allow the preparation of [2]rotaxane-based degenerate molecular shuttles featuring the recognition of pyridinium ions by BPX26C6 macrocycles. Because of the weak interactions between the BPX26C6 and pyridinium units in the [2]rotaxanes in CD₃COCD₃, the rates of shuttling of the BPX26C6 moieties between the pyridinium stations are rapid, relative to those of DB24C8-based shuttles, on the NMR spectroscopic time scale at ambient temperature.     

Anaerobic and aerobic sorption of cesium and selenium on mudrock

This study is focused on sorption and determination of distribution ratios (R _d) of cesium and selenium on mudrock, which is the potential host rock for waste disposal in Taiwan. Batch tests including sorption kinetic and isotherms tests have been performed in synthetic groundwater at aerobic and anaerobic conditions which might be found in the deep geologic environment. It is found that R _d for sorption of cesium did not have an obvious difference in both conditions with various contact time. However, R _d in anaerobic condition for sorption of selenium was greater than that in aerobic condition. Selenium is a redox sensitive element and its solubility in reducing conditions is controlled by the formation of metallic or precipitable selenium. It demonstrated variation of R _d with time in both conditions for Se sorption kinetic experiments was equal (10 ml/g) and indicated a part formation (10%) of precipitable selenium (Se⁰, FeSe or FeSe₂) in the solution. Moreover, it was not enough to form precipitable selenium completely in reducing condition as to insufficient experimental period (2 weeks) and in the presence of Fe²⁺. The Freundlich and Langmuir isotherm for the concentration ranges (i.e., 10⁻³–10⁻⁷M) conducted in both conditions seem to be adequate to quantitatively describe the sorption of cesium and selenium, respectively.     

Chemotaxonomy of Triterpenoid Pattern of HPLC of Ganoderma lucidum and Ganoderma tsugae

Three strains of Ganoderma tsugae (CCRC36065, CCRC37034, CCRC37038) and three strains of Ganoderma lucidum (CCRC36021, CCRC37029, CCRC37033) were cultivated. Their triterpenoid patterns of the fruit body were analyzed by reverse phase HPLC using a gradient elution of acetonitrile/2% acetic acid (1/4 and 1/2). The triterpenoid patterns of G. tsugae and G. lucidum are different. But similar 2 and 3 dimensional patterns are obtained among three strains of G. tsugae. Different patterns are found among different strains of G. lucidum. Ganoderic acid A( 1 ), B( 2 ), C( 3 ) and D( 4 ) were isolated from the ethanol extract of G. tsugae.     

新铜试剂的荧光光谱

研究了新铜试剂在水溶液中的荧光光谱和荧光量子产率,发现在强酸性条件下,其最大激发和发射波长分别为332nm和429nm,探讨了荧光产生的机理,以罗丹明6G为参比,测得新铜试剂的荧光量子产率为15.2%.     

雪松二醇-(R)-1氯-1-苯基甲基硼酸酯(phCHClBO_2C_(15)H_(24))的不对称合成和晶体结构

利用雪松二醇苯基硼酸酯进行不对称合成反应，制得标题化合物并测定结构．其晶体属正交晶系，空间群为P212121。结晶学多数为：a=5．728（3），b=8.543（3），c=41．267（7）A，V=2019．7A3；Z=4，Dc=1．23g／cm3，μ（CuKa）=17.7cm－1，R=0．0072，Rw=20．0077．独立可观察反射点数（I＞3σ（I））为739个。由晶体结构图可看出，由于雪松二醇基团的空间住阻效应，反应产物有很高的非对称选择性。     

HfO2顶层多层介质膜脉宽压缩光栅的离子束刻蚀

多层介质膜光栅是高功率激光系统的关键光学元件. 为了满足国内强激光系统的迫切需求,首先利用考夫曼型离子束刻蚀机开展了HfO₂顶层多层介质膜脉宽压缩光栅的离子束刻蚀实验研究. 采用纯Ar及Ar和CHF₃混合气体作为工作气体进行离子束刻蚀实验,获得了优化的离子源工作参数. 结果表明,与纯Ar离子束刻蚀相比,Ar和CHF₃混合气体离子束刻蚀时的HfO₂/光刻胶的选择比大. HfO₂的离子束刻蚀过程中再沉积效应明显,导致刻蚀光栅占宽比变大. 根据刻蚀速率分布制作的掩模遮挡板可以提高刻蚀速率均匀性,及时清洗离子源和更换灯丝,可保证刻蚀工艺的重复性. 利用上述技术已成功研制出多块最大尺寸为80 mm×150 mm、线密度1480线/mm、平均衍射效率大于95%的HfO₂顶层多层介质膜脉宽压缩光栅. 实验结果与理论设计一致,为大口径多层介质膜脉宽压缩光栅的离子束刻蚀提供了有益参考. 关键词： 光栅 多层介质膜 离子束刻蚀     

Heterostructured Tin oxide-pillared tetratitanate with enhanced photocatalytic activity

Here we point out that the nanocrystals well ordered in compact hexagonal networks are highly stable compared to the same nanocrystals either isolated on a substrate or ordered in a less compact manner. The emergence of unexpected collective physical intrinsic properties results in the nanocrystals being ordered over a long distance in colloidal crystals called supracrystals. Some morphologies of nanocrystals ordered, at the micrometer scale, in 3D superlattices called supracrystals are similar to those obtained with atoms in nanocrystals. From a comparison between vibrational and magnetic properties of supracrystals and aggregates composed of the same nanocrystals, it is proposed that nanocrystals in a supracrystal could behave as atoms in a nanocrystal. From these data a possible analogy between nanocrystals in a supracrystal and atoms in nanocrystals is proposed.     

一锅合成绿色到近红外发射的CdTe量子点

以3-巯基丙酸(MPA)为稳定剂,采用水相合成法制备了从绿色到近红外发射的CdTe量子点。系统研究了反应液pH值、镉和碲的物质的量之比及镉和3-巯基丙酸的物质的量之比等实验条件对CdTe量子点体系的发射波长和荧光量子产率的影响。在pH值为10.5,且nCd2+∶nTe2-∶nMPA=1∶0.05∶1.1的条件下,回流0.5 h,CdTe量子点体系在569 nm波长处的荧光量子产率达到30.8%;在7 h的回流时间内,制备的量子点的波长覆盖范围为525～730 nm。分别用X射线粉末衍射、透射电镜和红外光谱对CdTe量子点的晶体结构、形貌及表面基团进行表征。     

全息光刻中的驻波效应研究

对光刻胶内光强分布进行了计算与模拟, 结果表明, 来自基底的反射光与入射光干涉, 光强在垂直基底的方向上呈现强弱周期性变化, 即驻波效应. 进一步的分析与实验结果表明, 随着基底反射率的增加, 驻波效应变得严重, 进而影响光栅掩模的槽形、占宽比并限制线条高度. 为减弱驻波效应的影响, 尝试了使用减反射膜降低基底反射光强度, 实验结果表明, 在基底与光刻胶之间增加一层减反射膜吸收来自基底的反射光强度, 减弱驻波效应的效果显著. 关键词： 全息光刻 驻波 减反射膜     

Mutation of isoleucine 705 of the oxidosqualene-lanosterol cyclase from Saccharomyces cerevisiae affects lanosterol's C/D-ring cyclization and 17α/β-exocyclic side chain stereochemistry

Site-saturated substitution in Saccharomyces cerevisiae oxidosqualene-lanosterol cyclase at Ile705 position produced three chair-boat-chair (C-B-C) truncated tricyclic compounds, two 17α-exocyclic protosteryl intermediates, two protosteryl C-17 truncated rearranged intermediates and the normal biosynthetic product, lanosterol. These results indicated the importance of the Ile705 residue in affecting lanosterol's C/D ring stabilization including 6-6-5 tricyclic and protosteryl C-17 cations and 17α/β-exocyclic side chain stereochemistry.