北五味子果实、茎和叶中微量元素的测定

采用硝酸和过氧化氢混合酸体系作消化液,利用电感耦合等离子质谱(ICP-MS),对延边地区不同产地五味子中微量元素的含量,进行了测定和研究。测定了不同产地五味子叶、茎、果实中Mg、Ca、Fe、Zn、Cu、Mn、Cr?Ni?Pb?Cd等19种元素的含量水平。测定结果显示五味子中K、Ca、Mg、Fe含量丰富,而Pb、Cd的含量很低。不同地区的五味子茎、叶、果实中微量元素含量存在很大差异。     

Multiplex time-reducing quantitative polymerase chain reaction assay for determination of telomere length in blood and tissue DNA

In this paper we describe a multiplex time-reducing quantitative polymerase chain reaction (qPCR) method for determination of telomere length. This multiplex qPCR assay enables two pairs of primers to simultaneously amplify telomere and single copy gene (albumin) templates, thus reducing analysis time and labor compared with the previously established singleplex assay. The chemical composition of the master mix and primers for the telomere and albumin were systematically optimized. The thermal cycling program was designed to ensure complete separation of the melting processes of the telomere and albumin. Semi-log standard curves of DNA concentration versus cycle threshold (C _t) were established, with a linear relationship over an 81-fold DNA concentration range. The well-performed intra-assay (RSD range 2.4–4.7%) and inter-assay (RSD range: 3.1–5.0%) reproducibility were demonstrated to ensure measurement stability. Using wild-type, Lewis lung carcinoma and H22 liver carcinoma C57BL/6 mouse models, significantly different telomere lengths among different DNA samples were not observed in wild-type mice. However, the relative telomere lengths of the tumor DNA in the two strains of tumor-bearing mice were significantly shorter than the lengths in the surrounding non-tumor DNA of tumor-bearing mice and the tissue DNA of wild-type mice. These results suggest that the shortening of telomere lengths may be regarded as an important indicator for cancer control and prevention. Quantification of telomere lengths was further confirmed by the traditional Southern blotting method. This method could be successfully used to reduce the time needed for rapid, precise measurement of telomere lengths in biological samples.     

Optimal reactions for the synthesis of superheavy nucleus 270Hs

The superheavy nucleus 270 Hs iS expected to be a "double-magic" deformed nucleus.We have calculated its cross sections of evaporation residue for the reactions 248Cm(26Mg,4n)270Hs,244pu(30Si,4n)270Hs,238U(36S,4n)270Hs and 226Ra(48Ca,4n)270Hs using a two-parameter Smoluchowski equation.It is found from our results that 226Ra(48Ca,4n)270Hs and 238U(36S,4n)270Hs are two optimal reactions for the synthesis of the superheavy nucleus 270Hs due to their large negative Q-values.     

Facile One-Pot Method for the Synthesis of Novel N-Dichloroacetyl-1,3-oxazolidines

A short and efficient route to synthesis and structural characterization of a series of novel N-dichloroacetyl-5-ethyl-1,3-oxazolidine derivatives has been developed. These new compounds, characterized by the substitution at position 2 by alkyls, cycloalkanes, benzyls, or aryls, have been synthesized in good yields via a sequential procedure involving cycloaddition, condensation, and acylation. All the compounds are characterized by infrared, ¹H NMR, and ¹³C NMR.     

汽车尾气净化反应的UBI-QEP法研究

应用单位键指标%D二次指数势 (UBI QEP)方法对汽车尾气净化反应中氮氧化物的分解进行了理论分析 .结果表明 ,NOx 的分解的可能途径为氮氧化物的直接分解、CO还原助解和氮助解离 .在富氧条件下 ,以CO助解为主 .NO的解离存在N2 O中间态 .Ni与Rh一样 ,也是优秀的还原NOx 催化剂 ,若能有效克服表面氧的共吸附 ,Ni Cu可能是良好的汽车尾气净化催化剂的主体成份     

电力系统动模实验用50kJ高温超导储能磁体的设计研究

介绍了 2 0 K下对电力系统动模实验用 5 0 k J高温超导储能磁体的设计步骤 ,给出了用 Bi- 2 2 2 3单根超导带进行5 0 k J磁体线圈的设计和优化结果 ,分析了高温超导体的各向异性对磁体临界电流的影响和磁体漏磁的分布 ,并讨论了用单根高温超导带组成的超导体和用多根高温超导带组成的超导体设计的储能磁体的特性参数对改善电力系统动态特性的能力的影响。     

Liquid phase deposition of hemoglobin/SDS/TiO2 hybrid film preserving photoelectrochemical activity

This work demonstrates that liquid phase deposition (LPD) technique provides a novel approach to the immobilization of hemoglobin (Hb) in TiO(2) film for studying the direct electron transfer of Hb. Using the LPD process, a hybrid film composed of Hb, TiO(2) and sodium dodecylsulfonate (SDS) is successfully prepared on the electrode surface. The surface morphology of as-deposited Hb/SDS/TiO(2) film shows a flower-like structure. The cyclic voltammetric measurement indicates that the LPD hybrid film facilitates the electron transfer of Hb, which yields a pair of redox peaks prior to the characteristic voltammetric peaks of TiO(2). Due to the electrocatalytic activity of Hb towards H(2)O(2), the Hb/SDS/TiO(2) hybrid LPD film can be utilized as an H(2)O(2) sensor, showing a sensitive response linearly proportional to the concentration of H(2)O(2) in the range of 5.0×10(-7)-4.0×10(-5) mol/L. At the same time, the Hb/SDS/TiO(2) hybrid film preserves the photoelectrochemical activity of TiO(2). The photovoltaic effect on the electrochemical behavior of Hb/SDS/TiO(2) film is observed after long-time UV irradiation on the film, which could improve the calibration sensitivity for H(2)O(2).     

15N and 13C{14N} NMR investigation of the major nitrogen-containing segment in an aquatic fulvic acid: evidence for a hydantoin derivative

A nitrogen-rich segment in a fulvic acid (FA) from Pony Lake, a coastal pond in Antarctica, was investigated by (15)N and (13)C{(14)N} solid-state NMR techniques. As reported previously, the (13)C{(14)N} spectrum of C bonded to N exhibits a peak at 157 ppm that is assigned to an sp(2)-hybridized carbon bonded to at least two nitrogen atoms. This segment contains 48% of all N in the sample. (15)N NMR shows distinct signals, 20 ppm upfield and downfield from the typical peptide resonance; dipolar dephasing confirmed that they are due to protonated N. The well-resolved downfield peak, which accounts for 1/4 of the spectral area, cannot be assigned to aromatic heterocycles, such as purines, because the fraction of aromatic C bonded to N in this sample is very small. Analysis of (15)N chemical-shift trends and (15)N NMR of model compounds, such as arginine and its derivatives, excludes assignment to a guanidinium ion or to substituted guanidino groups. Similarly, ureido groups, -NH-CO-NH-, that are not bonded to a second C = O do not match the observed (15)N peaks in the FA, since both N resonate upfield from the peptide resonance. On the other hand, all chemical shifts are matched within the observed range by the -C(alkyl)-NH-CO-NH-CO-C structure found in two nonaromatic heterocycles, hydantoin and dihydrouracil. The five-membered hydantoin ring, which is found in the purine metabolite allantoin, provides a better match than the six-membered dihydrouracil ring. Regular uracil or thymine fails to produce adequate agreement with observed chemical shifts.     

Enhanced activity and SO2 resistance of Co-modified CeO2-TiO2 catalyst prepared by facile co-precipitation for elemental mercury removal in flue gas

The Co-modified CeO₂-TiO₂ catalyst prepared by facile co-precipitation was used for efficient elemental mercury oxidation in flue gas. Results indicated that Co doping greatly enhanced the activity and SO₂ resistance of the CeO₂-TiO₂ catalyst. In the presence of 5% O₂, 500 ppm NO, 800 ppm SO₂ and 3% H₂O at 200 °C, the Hg⁰ removal efficiency of CeCo₃/Ti could maintain at about 87% for a relatively long time. Characterizations of catalysts (BET, XRD, Raman spectroscopy, TEM, H₂-TPR, O₂-TPD, XPS, TG-MS and SO₂-DRIFTS) were carried out to reveal the mechanism of Co modification on the redox ability, SO₂ resistance and resultant mercury oxidation removal performance of catalyst. It was found that an interaction of Ce with Co promoted the dispersion of CeO₂, increased chemisorbed oxygen concentration, and improved the oxygen storage capacity and the reducibility of catalyst, which was beneficial to the improvement of Hg⁰ oxidation removal. Hg⁰ would adsorb onto the catalyst and react with surface active oxygen species replenished by gas-phase O₂ to be oxidized via Mars-Maessen mechanism. SO₂ consumed the surface active oxygen species and resulted in the reduction of Ce⁴⁺ to Ce³⁺, which induced the deactivation of catalyst. The introduced Co in CeO₂-TiO₂ catalyst exerted the function of protecting Ce⁴⁺ from being poisoned by SO₂ and thus promoted the sulfur resistance and Hg⁰ removal performance of the catalyst in the presence of SO₂.     

300kVA电动车组高温超导变压器电流引线与套管的结构设计

根据300kVA/25000V/866V电动车组高温超导变压器的绝缘和漏热要求,在理论优化设计的基础上,对电流引线与套管的结构进行再设计并使之工程实现。