Anti-oxidative action of ent-kaurene diterpenoids

Nine ent-kaurene diterpenoids, leukamenin E, glaucocalyxin A, wangzaozi A, epinodisinol, epinodosin, rabdosin B, rabdosinate, lasiokaurin and oridonin, were separated from Isodon racemosa (Hemsl) Hara and Isodon japonica (Burm.f) Hara var. galaucocalyx (maxin). The protection against DNA damage induced by hydrogen peroxide in human peripheral blood mononuclear cells (PBMCs) and inhibition of lipid peroxidation in rat liver microsome were studied with comet assay and thiobarbituric acid reactive substances determination. All nine diterpenoids showed concentration-dependent protection in DNA damage in human PBMCs induced by 50 μM H₂O₂. The effects were similar and weaker than quercetin. The inhibitions of lipid peroxidation were obviously difference. Rabdosin B and oridonin were the strongest inhibitors, followed by lasiokaurin and wangzaozin A. Rabdosinate was the weakest and others were medium. The structure-activity relationship is discussed.     

UPLC-TOF MS-Based Metabonomic Study on Coadministration of Huperzine A and Ligustrazine Phosphate for Treatment of Alzheimer’s Disease

This work was designed to assess the holistic efficacy of concurrent treatment with huperzine A (HA) and ligustrazine phosphate (LP) in the animal model, and to interpret the metabonomics characteristics of the poly-therapy in treating Alzheimer’s disease (AD). Metabolic profiling of the brain was performed using ultra performance liquid chromatography coupled to time-of-flight mass spectroscopy (UPLC-TOF MS). Principal component analysis and partial least squares discriminant analysis were utilized to classify and reveal the differences among the control, model and treatment groups. Ten potential biomarkers have been finally gained. The metabonomic results revealed that the coadministration of HA and LP might slow down the progression of AD through synergistic therapeutic efficacies, exhibiting better effect on amnesia compared with the mono-drug therapy. Importantly, the UPLC-TOF MS-based metabonomic approach would be a useful technique for the diagnosis of AD, the discovery of metabolic biomarkers and the evaluation of the treatment effects.

     

Kinetics of reaction between acetic acid and Ag2+ in nitric acid medium

The reaction kinetics between acetic acid and Ag²⁺ in nitric acid medium is studied by spectrophotometry. The effects of concentrations of acetic acid (HAc), H⁺, NO^?₃, and temperature on the reaction are investigated. The rate equation has been determined to be –dc(Ag²⁺)/dt = kc(Ag²⁺)c(HAc)c^?1(H⁺), where k = (610 ± 15) (mol/L)^?1 min^?1 with an activation energy of about (48. 8 ± 3.5) kJ mol^?1 when the reaction temperature is 25°C and the ionic strength is 4.0 mol L^?1. The reduction rate of Ag²⁺ increases with the increase in HAc concentration and/or temperature and the decrease in HNO₃ concentration. However, the effect of NO^?₃ concentrations within 0.5–2.5 mol L^?1 on the reaction rate is negligible. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 45: 47–51, 2013     

一类不定积分的复变函数解法

本文运用实变复值函数积分计算方法研究了一类不定积分的新解法,给出了它的显式计算公式.该方法不仅推广了许多近期文献的研究结果,而且具有计算简洁的优点.     

投资回报率模型及其应用

首次对房地产价格评估的投资法进行反向运用，对因投资而产生的二种截然不同的纯收益，其中之一是已知的，而另一是未知的，当投资回报率给定时，导出一个投资回报率模型。作为应用，得到开发区基准地价评估的投资回报率模型，从而得到一个开发区已开发区域内国家所能接受的最低整体地价水平，为开发区的基准地价确定奠定基础。最后通过实例说明．该模型在开发区基准地价评估过程中所起的主导的不可替代的作用。     

碳纳米管在分析化学领域的研究进展

综述了碳纳米管自发现以来在分析化学领域中的一些研究成果，重点介绍了碳纳米管的制备、纯化、修饰以及作为一种新材料在分析化学中的应用前景。参考文献40篇。     

硅胶填充柱反相洗脱毛细管电色谱研究

在７５μｍ（ｉ．ｄ．）×２７／２０ｃｍ的硅胶（３μｍ）填充柱上，以乙腈（９５：５）－Ｔｒｉｓ／ＨＣｌ缓冲液（ｐＨ８．３）为流动相，实施毛细管电色谱并对其保留机理进行了研究。研究表明，当采用反相洗脱时，硅胶填充柱显示出阳离子交换和正相分配双重保留机理。同时还对电渗流和热效应进行了研究。     

反相高效液相色谱法同时测定姜黄药材中3个组分的含量

建立了一种反相高效液相色谱方法,同时测定中药材姜黄块根中3组分的含量。采用KromasilTMC18柱(5μm,200mm×4.6mm),以磷酸水溶液(pH=2.5)和乙腈溶剂为流动相,梯度洗脱,流速0.9mL/min,柱温40℃,检测波长为425nm,10min内即可将3种组分分离测定。该方法快速、简便、准确,可为评价不同产地的姜黄质量提供依据。     

铒偏析与沉淀对掺铒硅1.54 μm光发射的影响

用金属蒸气真空弧离子源(MEVVA)制备高浓度掺铒硅发光薄膜, 研究高浓度Er掺杂发光薄膜中Er的偏析与沉淀现象对1.54 μm光发射的影响. RBS分析表明, Er的掺杂浓度可达～10%(原子分数), 即Er原子体浓度为1×1021 cm-3. XRD分析掺铒硅薄膜的物相结构发现, Er在薄膜中的存在形式与离子注入参数有关. Er的偏析、沉淀以及辐照损伤等因素会影响掺铒硅薄膜的1.54 μm光发射.     

A selective voltammetric method for uric acid detection at beta-cyclodextrin modified electrode incorporating carbon nanotubes

A beta-cyclodextrin-coated electrode incorporating carbon nanotubes was constructed and applied to the detection of uric acid in the presence of high concentration of ascorbic acid. The major obstacle of the overlapped oxidation potential of ascorbic acid was overcome owing to the distinct ability of the carbon nanotubes-modified electrode to yield a large anodic peak difference ca. 400 mV. The sensitive detection of uric acid has been further improved by the formation of a supramolecular complex between beta-cyclodextrin and uric acid. A linear calibration curve was obtained for 5 x 10(-7) to 5 x 10(-5) M in 0.2 M HAc-NaAc buffer (pH 4.5) with correlation coefficient of 0.998 and detection limit of 0.2 microM. The practical analytical application was illustrated by a selective measurement of uric acid in human urine without any preliminary treatment.