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- Author or Editor: X. Wang x
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Traditional Chinese medicine (TCM) has been widely used in many countries for thousands of years and played an indispensable role in the prevention and treatment of diseases, especially the complicated and chronic ones. However, the application of TCM in diseases is still not fully recognized by people around the world, the main reason is that Chinese herb is a very complex mixture containing hundreds of different components. Thus, it is essential to make quality control and evaluation of TCM. A new quality evaluation method, quantitative analysis of multi-components by single marker (QAMS), was developed to the quality control of alkaloids in TCM, a case study on Radix aconiti lateralis, named Fuzi in Chinese. Six alkaloids, including aconitine, hypaconitine, mesaconitine, benzoylaconine, benzoylmesaconine, and benzoylhypaconine, were selected as main components to evaluate the quality of Radix aconiti lateralis. The feasibility and accuracy of QAMS were checked by the external standard method, and various high-performance liquid chromatographic instruments and chromatographic conditions were investigated to verify its applicability. Using aconitine as the internal reference substance and the content of aconitine was calculated according to relative correction factors by high-performance liquid chromatography. The present results showed that there was no significant difference observed between the QAMS method and the external standard method with the relative average deviations less than 3.0%, and QAMS is an effective way to control the quality of herbal medicines and seems to be a convenient and accurate approach to analyze multi-composition when reference substances are unavailable.
Abstract
DTPA-Octreotide(Pentetreotide), a somatostatin analogue which can bind specifically and with high affinity to somatostatin receptor in vitro and vivo, labeled with99mTc by tin reduction in acetate buffer, has been characterized by Reverse-phase High performance Liquid Chromatography. The effect of different solvents, mobile phase pH, linear gradient and the injected volume on the separation efficiency was evaluated. The results show that the separation efficiency is best using μBondapak-C18 (300×3.9 mm2), linear gradient of 40% to 80% methanol (1.0 ml/min) in 0.05M acetate buffer (pH 5.5) over a 30 min period and maintaining for another 10 min. The labeled product is a mixture which mainly consists of five components (a, b, c, d, e) successfully proved by HPLC. Paper chromatography is also evaluated in this paper. It may be used to determine the radiochemical purity of the labeling product, but is not a good choice for the verification each components.
Abstract
The stability constants for tracer concentrations of Co(II) complexes with the red earth fulvic acid were determined at pH 3.8–6.8 and ionic strength 0.0010–1.0 mol/l by using the cation exchange equilibrium method and the radiotracer60Co. The effects of ionic strength and pH on the stability constants of 1∶1 Co(II) complexes were investigated, and it was found that the stability constants of complexes of humic substances do not vary with ionic strength and pH in a manner similar to that of simple complexes.
Abstract
The sorption of Eu(III) on calcareous soil as a function of pH, humic acid (HA), temperature and foreign ions was investigated under ambient conditions. Eu(III) sorption on soil was strongly pH dependent in the observed pH range. The effect of ionic strength was significant at pH < 7, and not obvious at pH > 8. The type of salt cation used had no visible influence on Eu(III) uptake on soil, however at low pH values, the influence of anions was following the order: Cl− ≈ NO3 − > ClO4 −. In the presence of HA, the sorption edge obviously shifted about two pH units to the lower pH, whilst in range of pH 6–7, the sorption of Eu(III) decreased with increasing pH because a considerable amount of Eu(III) was present as humate complexes in aqueous phase, then increased again at pH > 11. The results indicated that the sorption of Eu(III) on soil mainly formed outer-sphere complexes and/or ion exchange below pH ~7; whereas inner-sphere complexes and precipitation of Eu(OH)3(s) may play main role above pH ~8.
Abstract
A complex of N,N'-ethylenebis(salicylideneiminato)diaquochromium(III) nitrate, [Cr(salen)(H2O)2]NO3 was characterized and its decomposition mechanism was studied by TG. The IR spectrum and X-ray analysis were examined for the complex. The non-isothermal kinetic data were analyzed by means of the Achar method and the Coats—Redfern method. The most probable kinetic model function was suggested by comparison of the kinetic parameters.
Abstract
Polyimide BTDA-ODA sample was prepared by polycondensation or step-growth polymerization method. Its low temperature heat capacities were measured by an adiabatic calorimeter in the temperature range between 80 and 400 K. No thermal anomaly was found in this temperature range. A DSC experiment was conducted in the temperature region from 373 to 673 K. There was not phase change or decomposition phenomena in this temperature range. However two glass transitions were found at 420.16 and 564.38 K. Corresponding heat capacity increments were 0.068 and 0.824 J g–1 K–1, respectively. To study the decomposition characteristics of BTDA-ODA, a TG experiment was carried out and it was found that this polyimide started to decompose at ca 673 K.
Summary
In 1951, 6.7 liters of an aqueous acidic solution of irradiated uranium (360 GBq) leaked from a buried storage tank into unsaturated prairie soil, where it has remained, undisturbed. In October 2001, sonic drilling was conducted to recover core samples around and below the tank location. This paper describes the measurements and investigative approaches being pursued to determine the transport properties of the various fission and daughter products and actinides. Separate effects laboratory experiments are also being conducted involving both inert and radioactive samples in similar soil, to examine the effects on transport properties (diffusion and sorption) of temperature, recharge and discharge rates, concentration and soil porosity. Finally, transport modeling approaches are discussed.
Abstract
The effects of cisplatin and its trans isomer transplatin on the thermal denaturation of G-actin were studied with a Micro DSC-III differential scanning calorimeter. The denaturation enthalpy of G-actin was found to be 12 J g–1, and the denaturation temperature was 328 K. The thermal denaturation curve showed that increasing cisplatin concentration decreased the enthalpy change. However, after the ratio of cisplatin to G-actin attained 8:1 (mol:mol), the denaturation enthalpy no longer decreased. Transplatin decreased the enthalpy change more rapidly. In contrast with cisplatin, the denaturation peak at 328 K disappeared, and a strong exothermic peak appeared at 341 K when the ratio of transplatin to G-actin was 8:1 (mol:mol). The enthalpy change was 75 J g–1, which is far in excess of the range of weak interactions. This strong exothermic phenomenon probably reflects the agglutination of protein. The effects of cisplatin and transplatin on the number of the free thiol groups of G-actin are discussed.
Abstract
The heat capacities of 2-benzoylpyridine were measured with an automated adiabatic calorimeter over the temperature range from 80 to 340 K. The melting point, molar enthalpy, Δfus H m, and entropy, Δfus S m, of fusion of this compound were determined to be 316.49±0.04 K, 20.91±0.03 kJ mol–1 and 66.07±0.05 J mol–1 K–1, respectively. The purity of the compound was calculated to be 99.60 mol% by using the fractional melting technique. The thermodynamic functions (H T–H 298.15) and (S T–S 298.15) were calculated based on the heat capacity measurements in the temperature range of 80–340 K with an interval of 5 K. The thermal properties of the compound were further investigated by differential scanning calorimetry (DSC). From the DSC curve, the temperature corresponding to the maximum evaporation rate, the molar enthalpy and entropy of evaporation were determined to be 556.3±0.1 K, 51.3±0.2 kJ mol–1 and 92.2±0.4 J K–1 mol–1, respectively, under the experimental conditions.
Abstract
The heat capacities of trans-(R)-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid in the temperature range from 78 to 389 K were measured with a precise automatic adiabatic calorimeter. The sample was prepared with the purity of 0.9874 mole fraction. A solid-liquid fusion phase transition was observed in the experimental temperature range. The melting point, T m, enthalpy and entropy of fusion, Δfus H m, Δfus S m, were determined to be 344.75±0.02 K, 13.75±0.07 kJ mol−1, 39.88±0.21 J K−1 mol−1, respectively. The thermodynamic functions of the sample, H (T)-H (298.15), S (T)-S (298.15) and G (T)-G (298.15), were reported with a temperature interval of 5 K. The thermal decomposition of the sample was studied by TG analysis, the thermal decomposition starts at ca. 421 K and terminates at ca. 535 K, the maximum decomposition rate was obtained at 525 K. The order of reaction, pre-exponential factor and activation energy, are n=0.14, A=1.15·108 min−1, E=66.27 kJ mol−1, respectively.
