计时电流的因子分析-法拉第电流与充电电流的分离

基于电化学理论电流公式,用迭代目标变换因子分析法对计时电路曲线进行处理,得到分离的法拉第电流和充电电流成分,对于简单的电极过程,分离效果很好,信噪比得到提高,法拉第电流分量可用于定量分析。     

First total synthesis of (±)-adunctin B

The first total synthesis of (±)-adunctin B (1), a natural product isolated from Piper aduncum (Piperaceae) and having antibacterial activity, was achieved in 1.26% overall yield in 15 steps from 5,7-dimethoxycoumarin-3-carboxylate (8).     

Maintaining the predictive abilities of multivariate calibration models by spectral space transformation

In quantitative on-line/in-line monitoring of chemical and bio-chemical processes using spectroscopic instruments, multivariate calibration models are indispensable for the extraction of chemical information from complex spectroscopic measurements. The development of reliable multivariate calibration models is generally time-consuming and costly. Therefore, once a reliable multivariate calibration model is established, it is expected to be used for an extended period. However, any change in the instrumental response or variations in the measurement conditions can render a multivariate calibration model invalid. In this contribution, a new method, spectral space transformation (SST), has been developed to maintain the predictive abilities of multivariate calibration models when the spectrometer or measurement conditions are altered. SST tries to eliminate the spectral differences induced by the changes in instruments or measurement conditions through the transformation between two spectral spaces spanned by the corresponding spectra of a subset of standardization samples measured on two instruments or under two sets of experimental conditions. The performance of the method has been tested on two data sets comprising NIR and MIR spectra. The experimental results show that SST can achieve satisfactory analyte predictions from spectroscopic measurements subject to spectrometer/probe alteration, when only a few standardization samples are used. Compared with the existing popular methods designed for the same purpose, i.e. global PLS, univariate slope and bias correction (SBC) and piecewise direct standardization (PDS), SST has the advantages of implementation simplicity, wider applicability and better performance in terms of predictive accuracy.     

Preparation of Multilayered 1,2-Ethylene-silica Nanotubes Through a Dual-templating Approach

Multilayered 1,2-ethylene-silica nanotubes were prepared with cetyltrimethylammonium bromide(CTAB)as a template and(S)-β-citronellol(CN)as a co-structure-directing agent.For a better understanding of t...     

自然光照下PEG/PAA凝胶在Fe~(3+)/CA溶液中的凝胶-溶胶转化行为

将PEG/PAA凝胶浸入铁/柠檬酸(Fe3+/CA)溶液中,自然光照一定时间可实现凝胶-溶胶的相互转化,而且转化行为受溶液的组成及其p H影响。只有当溶液中[Fe3+]0∶[CA]0≤1∶2,且溶液的p H在1~6之间,该转化才会发生,通过改变溶液中[Fe3+]0∶[CA]0的值或溶液的p H可以有效地控制其转化速率。此外,结果还表明,当凝胶转化为溶胶后,向其中加入高价金属阳离子,例如Fe3+、Al3+、Ce4+、Cu2+等,溶胶又会再次转化为凝胶。由于这种新颖的特性,该凝胶有望应用于药物释放、细胞培养等领域。     

Preparation and characterization of pentaerythritol/butane tetracarboxylic acid/polyethylene glycol crosslinking copolymers as solid-solid phase change materials

Pentaerythritol/butane tetracarboxylic acid/polyethylene glycol (PBPEG) crosslinking copolymers as a novel solid-solid phase change material (SSPCM) were successfully synthesized through the reaction mechanism and conditions of hydroxyl-carboxyl condensation reaction. The composition and chemical structure, crystalline properties, phase change behaviors, thermal reliability and chemical stability of PBPEG crosslinking copolymers were investigated by Fourier transform infrared spectroscopy (FT-IR), wide-angle X-ray diffraction (WAXD), polarization optical microscopy (POM), differential scanning calorimetry (DSC), and thermogravimetry (TGA), respectively. The results show that PBPEG crosslinking copolymers have typical solid-solid phase transition temperatures in the range of 10.31～53.27°C and high latent heat enthalpy in the range of 89.6～102.8 J/g, the synthesized SSPCMs have good thermal reliability and chemical stability after 300 thermal cycles, and PBPEG crosslinking copolymers have good thermal stability before 364°C. In summary, the synthesized PBPEG crosslinking copolymers could be potentially used for thermal energy storage.     

Room Temperature Solid State Reaction Involving Structural Transformation of Covalent Oxide Network

An interesting structural transformation from a two dimensional (2d) covalent oxide network with a layered structure to a three-dimensional (3d) network with a tunnel structure was found at room temperature in the mixture of hydrated alkali-metal molybdenum bronze and amorphous alkali-metal molybdate. From various experimental results it was concluded that the transformation was due to a room temperature solid state reaction.     

Data handling in HPLC-diode array UV-spectrometry

Summary The mathematical resolution of overlapped chromatographic peaks obtained in HPLC with a diode array UV detector has received considerable attention recently. The purpose of the proposed methods is the quantitation and identification of unknown solutes in complex mixtures by an efficient use of all available data. Basically two approaches have been proposed: the first one resolves the concentration profiles and calculates the pure spectra by applying a minimal number of assumptions, which is denoted self-modeling-curve resolution. The second one is based on a match of pure spectra available in a spectral library with the measured mixture spectra. In this paper both approaches are evaluated with respect to their performance to provide the pure spectra and an accurate quantitation of the concentrations.     

Study on Phase-Formation Mechanism and Intergrowth for Bi(Pb)-Sr-Ca-Cu-O System

In this paper, the phase-formation mechanism of Bi-based superconductors was systematically investigated by using high-temperature X-ray diffraction, differential thermal analysis (DTA) and crystallization of amorphous state. The transformations among Bi-based 2201, 2212 and 2223 phases were observed, and the intergrown phenomenon of the 2201, 2212 and 2223 phases was explained. It was proposed that there exist a composition equilibrium between 2212 phase and Ca2CuO3 and a competition of thermody-namic stability among Ca2CuO3, 2212 and 2223 phases. This is why it is difficult to prepare the 2223 phase. After Pb was doped in Bi-Sr-Ca-Cu-O system, Ca2CuO3 phase in the Bi-Sr-Ca-Cu-O system was replaced by Ca2PbO4, so that the composition equilibrium and competition of thermodynamic stability mentioned above were avoided.     

Genetic Transformation of Lycium barbarum L. via A. tumefaciens

A system for transformation and regeneration of Lycium barbarum L. , an important Chinese medical plant, has been established. Young stem segments from Lycium barbarum L. were infected with Agrobacterium tumefaciens C58cl(pGV3850: :ineo1130), and the transformed calli selected from the callus induction medium containing 50 fig/ml kanamycin could regenerate buds on differentiation medium containing 25 μg/ml kanamycin. 30% of the regenerated buds were normal in morphology. The normal buds could develop into whole plantlets after they were transferred to the rooting medium to induce roots. Nopa-line detection, NPT-Ⅱ enzyme activity assay and Southern blotting hybridization indicated that the foreign genes had been integrated into the genome of Lycium barbarum L. and expressed in the plant. In the processes of experiments, it was found that (i) after the pre-processes, the explants which formed callus quickly were easy to transform ; (Ⅱ) the rate of normal regenerated plants from transgenic calli was hig