过渡金属对分子筛担载Pd催化剂上CO氧化性能影响

分别采用共浸和连续浸渍法制备了一系列添加过渡金属的Pd-M-Ox-NaZSM-5(M=Cr，Mn，Fe，Co，Ni，Cu，Zn，Mo，Zr等)负载型催化剂．以CO氧化为探针反应，考察了不同制备方法对CO氧化性能影响，结果表明共浸法制备的各催化剂其活性明显优于连续浸渍法．详细考察了反应温度、Fe含量、氢气预还原、空速以及水蒸气等对共浸Pd-Fe-Ox-NaZSM-5催化剂上CO氧化行为影响，并应用XRD和XPS等手段对催化剂体相结构和表面状态进行了表征．结果表明：加入Fe2O3可明显提高Pd/NaZSM-5催化剂活性，且催化CO氧化的转化率随反应温度及Fe含量增加而增加；空速增加以及H2预还原作用导致Pd-Fe-Ox-NaZSM-5活性有所降低；催化剂对水蒸气较为敏感．XRD测试结果表明催化剂中Pd组分处于较高分散状态，以红铁矿形式存在的Fe2O3的引入，促进了Pd物种在NaZSM-5载体上的分散．表面XPS分析证实Fe2O3与Pd物种间存在较强的相互协同作用，且催化剂表面Pd物种处于较高氧化状态．Pd的高分散及其与Fe2O3的相互协同作用是共浸催化剂具有高活性的关键因素．     

Synthesis and anticancer activities of 5,6,7-trimethylbaicalein derivatives

The aim of this study was to develop potential anticancer agents based on a naturally occurring baicalein, a flavonoid from Scatellariae radix. Cinnamic acid derivatives were converted to corresponding chlorides and then condensed with 3,4,5-trimethoxyphenol in the presence of BF(3) x Et(2)O to give chalcones. Intramolecular cyclization of these intermediates by the actions of DMSO/I(2) afforded the desired trimethylbaicalein derivatives. Cell viability after treatment with the tested compound for 2 d was determined by a colorimetric MTT assay. The results indicated that most of the derivatives showed improved inhibition of proliferation of Hep G2 cells. Compound 9 was the most potent, in which the cell viability was reduced to <2% at the 25 microM level. In the case of Hep 3B cells, 8a, 8b and 8f showed moderate inhibition of their proliferation and 25 microM was required to reduce the viability to ca. 30%. On the other hand, prostate DU145 cells were more resistant. Most of the derivatives caused a 60% inhibition of DU145 cells only at a concentration of 100 microM or above.     

倒数示波计时电位滴定新技术

倒数交流示波极谱具有抑制充电电流、突出电解电流的优点,利用(dE/dt)~(-1)-E曲线上去极剂峰的突然消失或出现指示滴定终点的方法称作倒数示波计时电位滴定法.由运算放大器组装的模拟电子线路可以对(dE/dt)~(-1)-E曲线进行反馈、反对数及微分处理,从而获得各种类型的倒数示波计时电位曲线(图1),以进一步提高滴定的灵敏度。     

Hydrothermal in situ Ligand Synthesis from 1,10-Phenanthroline-5,6-dione and Characterization of 1D Coordination Polymers [Co（bpdc）（H2O）3] · H2O and [Cu（bpy）V2O6]

Hydrothermal treatment of MCl2(M=Co or Cu), NH4VO3, and 1,10-phenanthroline-5,6-dione(pdon) resulted in the formation of a duplex coordination polymer [Co(bpdc)(H2O)3]·H2O(bpdc=2,2′-bipyridine-3,3′-dicarboxylate) and a chain-like coordination polymer [Cu(bpy)V2O6](bpy=2,2′-bipyridine). X-ray single-crystal structural analysis shows that under hydrothermal conditions and in the presence of different transition metals, the organic reagent pdon was transformed in situ into bpdc and bpy, respectively. Mechanism of the in situ ligand synthesis reaction has been discussed.     

选相示波伏安法

选相示波伏安法毕树平，都思丹，高鸿（南京大学化学系，２１０００８）关键词示波计时电位法，选相示波伏安法，切口示波计时电位法是利用ｄＥ／ｄｔ～Ｅ曲线上切口的高度或深度进行定量分析的方法［１］，但由于ｄＥ／ｄｔ曲线主要反映充电电流的变化，从而使该方法的检...     

Small World Effects in a Harmonious Unifying Hybrid Preferential Model Networks

Small world effects in the harmonious unifying hybrid preferential model (HUHPM) networks are studied both numerically and analytically. The idea and method of the HUHPM is applied to three typical examples of unweighted BA model, weighted BBV model, and the TDE model, so-called HUHPM-BA, HUHPM-BBV and HUHPM-TDE networks. Comparing the HUHPM with current typical models above, it is found that the HUHPM networks has the smallest average path length and the biggest average clustering coefficient. The results demonstrate that the HUHPM is more suitable not only for the un-weighted models but also for the weighted models.     

利用界面激基复合物发射大致估算稀土配合物LUMO能级

研究了一种利用无荧光稀土配合物与同一受体材料形成的界面激基复合物的发射来大致估算其最低未占据轨道(LUMO)能级简单方法.镥、钆、钪三种稀土配合物与星形爆炸物形成的激基复合物发射峰位分别在590,607和656 nm,与此相对应LUMO能级计算结果大致为3.0,3.06,3.21 eV.     

微波辅助萃取-HG-AFS测定土壤中无机砷

采用微波辅助萃取分析物,联合原子荧光光谱技术,建立了微波辅助萃取-HG-AFS测定土壤中无机砷的分析方法。用正交试验设计结合单因素试验优化了样品粒度、萃取温度、萃取时间、固液比等微波萃取条件,研究了共存离子对无机砷测定的干扰情况。方法的线性范围为1.0~160.0μg/L,无机砷的检出限为0.20μg/L,相对标准偏差为0.3%,样品回收率为93.0%~98.5%。用本法分析3个不同产地有代表性土壤中无机砷量。     

基于布拉格光栅的边坡监测实验研究

提出了一种基于分布式光纤光栅的边坡监测与报警系统.根据强度折减法,利用ANSYS软件分析出边坡的软弱面及滑体所在的具体位置,从而在该处安装经过特殊封装的拉线式光纤光栅位移传感器.滑体的位移通过拉线转换为作用在光栅上的应力,而光纤光栅反射波长与应变具有良好的线性关系,因此通过检测光栅反射光的中心波长的偏移量,就可以解调出...     

EAST超导托卡马克装置中的大型超导磁体技术

随着大型超导核聚变装置、超导储能装置、超导强磁场装置及高能超导加速器技术参数的不断提高,大型超导磁体的应用也在加速发展中.大型超导磁体的场强较高、储能较大,对导体的结构、磁体结构、绝缘结构、制造工艺等要求与通常小型超导磁体有很大的不同.本文旨在对国家重大科学工程项目"EAST(HT-7U)超导托卡马克核聚变实验装置"的大型超导磁体关键技术作一介绍.