Simultaneous determination of triterpene saponins in ginseng drugs by high-performance liquid chromatography

A HPLC method for the simultaneous determination of 11 triterpene saponins with four-type aglycones (protopanaxadiol, protopanaxatriol, ocotillol and oleanolic acid types) in Ginseng drugs was developed and validated. Using a gradient of acetonitrile and 10 mM K-phosphate buffer (pH 5.80) as the mobile phase and UV detection at 196 nm, more than 18 ginsenosides with different aglycones were separated satisfactorily within 60 min. The detection limits (signal/noise> or =3) were 0.1 microg for ginsenosides Rb1, Rc, Rd, Re and Rg1, chikusetsusaponin III, and notoginsenoside R2, 0.2 microg for gisenoside Ro and chikusetsusaponin IVa, 0.3 microg for chikusetsusaponin IV, and 3 microg for majonoside R2. The calibration curve of each saponin had a correlation coefficient close to 1. Intra- and interday precisions were less than 2.1% (n=5) and 3.3% (n=15), respectively. The recovery rates of extraction were in the range of 96.4-102.7% for all ginsenosides. By adopting this method, the determinations of 11 ginsenosides in three Ginseng drugs derived from Panax ginseng, Panax vietnamensis var. fuscidiscus and Panax japonicus (Japan) were achieved.     

Synthesis and Characterization of Novel Organosoluble Methyl Substituted Poly(aryl Ether Ketone)s Containing Sulfone Linkage

Several new methyl substituted poly(aryl ether ketone)s containing sulfone linkage with inherent viscosities of 0.62–0.84 dL/g have been prepared from 4,4′‐bis(2‐methylphenoxy)diphenylsulfone and 4,4′‐bis(3‐methylphenoxy)diphenylsulfone with terephthaloyl chloride and isophthaloyl chloride by electrophilic Friedel‐Crafts acylation in the presence of DMF with anhydrous AlCl₃ as a catalyst in 1,2‐dichloroethane, respectively. These polymers having weight‐average molecular weight in the range of 71,000–49,000 are all amorphous and show high glass transition temperatures ranging from 167 °C to 191 °C, excellent thermal stability at temperatures over 400 °C in air or nitrogen, high char yields of 51–58% in nitrogen and good solubility in CHCl₃ and polar solvents such as DMF, DMSO and NMP at room temperature.     

SAPO-34分子筛骨架稳定性的研究

利用差热分析，原位ＸＲＤ技术，高温条件下的焙烧和水蒸气处理并关联其催化性能变化，研究了ＳＡＰＯ－３４分子筛的热及水热稳定性，差热分析结果表明，ＳＡＰＯ－３４的骨架破坏温度高于１３００Ｋ，原位ＸＲＤ跟踪研究证实，ＳＡＰＯ－３４分子筛原粉在高温焙烧以除掉有机胺及随后的降温过程中无明显的骨架破坏；而焙烧型ＳＡＰＯ－３４在空气中放置一定时间后，水分子吸附微孔中明业降低样品的ＸＲＤ峰强度，且降低幅度随放置时     

担体对Fe—MnO催化剂CO＋H2反应性能的影响

考察氧化物担体对Fe-MnO催化剂反应性能影响的结果表明,担体的类型对Fe-MnO催化剂CO加氢反应性能影响很大,其低碳烯烃选择性相差悬殊,Al_2O_3、SiO_2和MgO担载的Fe-MnO催化剂都不利于低碳烯烃的生成,而TiO_2担载的Fe-MnO催化剂则具有较高的烯烃选择性和催化活性。从担体-金属相互作用本质的差异,研究了担体对金属活性组分化学状态的影响及催化活性相与F-T合成烯烃的关系,发现担体-金属间的电子效应有利于催化剂活性和选择性的提高,其它物理化学效应引起的相互作用则不利于改善催化剂性能;还表明Fe_(?)C是催化活性相,Fe~(2+)物种的存在不利于提高烯烃的选择性。     

内噪声作用下的随机共振算法对弱信号的检测

基于随机共振理论提出了一种简便、有效地检测弱信号的方法。在内噪声协同作用下，通过调节输入噪声信号的大小能较好地提高系统输出信号的信噪比，从而实现检测背景噪声很强的弱信号的目的。应用于模拟信号和实验信号的结果证明了方法是可行的。     

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利用太阳能光解水制氢和降解有机污染物对解决能源和环境问题具有重要意义，而可见光响应催化剂的研制是实现太阳光高效利用的关键。本文从可见光响应光催化剂的设计思路出发，从电子能带结构、固溶体结构和微观复合结构三方面介绍了目前光催化剂的研究进展和发展方向。     

Photophysical properties of oligo(2,3-thienyleneethynylene)s

Photophysical properties of oligo(2,3-thienyleneethynylene)s (nTE, n denotes the number of thiophene rings, n = 2, 3) in benzene were investigated using steady-state, time-resolved fluorescence, and transient absorption spectroscopies. For 2TE, generation of the radiative S2 and nonradiative S1 states was confirmed. Upon excitation, the S2 state was initially generated and deactivated to the S1 state within 10 ps. The S1 state exhibited the transient absorption band at 470 nm, of which the lifetime was estimated to be 5.3 ns. In the case of 3TE, on the other hand, it was revealed that the radiative S1 state with a transient absorption peak at 650 nm was generated upon excitation. The T1 states of nTE were generated from the S1 states. The quantum yields were estimated to be 0.52 and 0.54 for 2TE and 3TE, respectively. Extremely fast reactions in the higher triplet excited state were indicated for both 2TE and 3TE.     

TiO2／Ti／TiO2半导体隔片光电化学电池的性能

研究了半导体隔片光电化学电池(SC-SEP)中光池溶液的pH、暗池溶液的氧化还原电对以及两池中的暗电极对电池的开路电压、光生电压、短路光电流和光伏安特性的影响。对它们的影响机制进行了初步分析。通过合理选择电池体系,SC-SEP的性能可比单隔室的光电化学电池(PEC)优越。     

电解池电阻和容抗的快速测定仪

利用锁定放大器, 恒电势仪, 压控频率正弦波信号发生器等组装成电解池电阻和容抗的快速测定仪。可以快速地自动测是和绘出阻抗谱图和电阻/容抗～时间图。采用微小恒定振幅正弛交流电流(<10 μA)作为微扰, 数据可能较为可靠。给出了线路及所需滤波器元件的数据, 说明仪器各部份之间的干扰可以减少。测定了滴汞电极在1 mol L~(-1)Na_2SO_4溶液中及1 mol L~(-1)Na_2SO_4被正庚醇饱和的溶液中的微分电容～电势数值。证明仪器工作良好。另外, 从实验数据和理论分析, 均表明D.C.Grahame的被广泛引用的有关经典数据有误。本文做了修正。还测定了半导体氧化铁电极在光照下黑暗中的阻抗谱图和氧化银电极充电和停止充电后开路下的电阻～时间图, 显示了仪器在电化学研究中利用的可能性。     

新型显色剂3,3,5,5''''-四甲基联苯胺分光光度法测定余氯的研究

本文报道了采用新型氧化还原剂3,3’,5,5’-四甲基联苯胺(TMB)测定水中总余氯的分光光度法,并对其灵敏度、稳定性、准确性作了较为详细的研究,探讨了分析条件,提出了分析方法。在pH≤2时,最大吸收峰为450 nm,表观摩尔吸光系数为6.89×10~4L·mol~(-1)·cm~(-1),可测范围为0.01～2.5 mg/L。与目前使用的传统显色剂邻联甲苯胺(DMB)相比较,具有灵敏度高,显色稳定,重现性好及使用安全等优点。