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  • Author or Editor: Jin Wang x
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Abstract  

The important role of the Institute for Scientific Information'sScience Citation Index (SCI) as an international retrieval and evaluation tool is briefly discussed. The role ofChinese Science Citation Database (CSCD), the counterpart of SCI in China, in improving the application of citation retrieval method in China, is summarized. The construction process and status quo of CSCD are explained.

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Abstract  

The 99mTc(CO)3(H2O)-DEDT complex was prepared by a two-step procedure involving the preparation of the precursor fac-[99mTc(CO)3(H2O)3]+, followed by the addition of sodium salt of diethyl dithiocarbamate (DEDT). The radiochemical purity (RCP) of the product was over 90% as measured by thin layer chromatography (TLC). No decomposition of the complex at room temperature was observed over a period of 6 hours. Its partition coefficient indicated that it was a lipophilic complex. The electrophoresis results showed the complex was neutral. Biodistribution in mice demonstrated that the complex can penetrate the intact blood-brain barrier (BBB) and the brain uptake (ID%/g) was 4.22 at 5-minute post-injection, suggesting the complex may lead to a further development of the radiopharma ceutical as a brain perfusion tracer.

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Abstract

The synergistic flame-retarded systems consisting of nano-ZrO2 and triphenylphosphate(TPP) for poly(methyl methacrylate)(PMMA) are reported. The synergistic effects were studied by cone calorimeter test, thermal gravimetric analysis (TG), Raman spectra, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The synergistic effect of nano-ZrO2 with TPP could be clearly observed by cone calorimeter test. The Raman spectra, SEM, and XPS results provide evidence that nano-ZrO2 can efficiently promote the formation of charred layers composed of varying amounts of graphite and amorphous carbon. The possible mechanisms for synergy are discussed.

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Abstract

The nano poly(phenylsilsesquioxane) spheres (nano-PPSQ) were prepared by the sol–gel method and incorporated into poly(methyl methacrylate) (PMMA) by in situ bulk polymerization of methyl methacrylate. The structure of nano-PPSQ was confirmed by transmission electron microscope and thermogravimetry analysis (TG). The interaction between nano-PPSQ and PMMA was investigated by Fourier transform infrared spectra (FT-IR). The influence of nano-PPSQ on the thermal stability of PMMA was investigated by TG and differential scanning calorimetry (DSC) measurements. The results indicated that nano-PPSQ enhanced the thermal stability and the temperatures of glass transition (T g) of nanocomposites. The effect of the heating rate in dynamic measurements (5–30 °C min−1) on kinetic parameters such as activation energy by TG both in nitrogen and air was investigated. The Kissinger method was used to determine the apparent activation energy for the degradation of pure PMMA and nanocomposites. The kinetic results showed that the apparent activation energy for degradation of nanocomposites was higher than that of pure PMMA under air.

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Abstract  

The solvent extraction of several lanthanide radionuclides (144Ce,147Nd,154Eu,170Tm and169Yb from aqueous picric acid solutions with (4-methylbenzo-15-crown-5) in chloroform has been investigated. The extracted species are found to be 1∶2∶3 (metal/crown/ picrate) complexes from slope analysis. The extraction equilibrium constants (Kex) have been determined at 25 °C. The order of Kex values for trivalent lanthanides is Nd3+> >Eu3+>Ce3+>Tm3+>Yb3+. This suggests that the ionic size of Nd3+ (r=0.995 Å) may be nearer to the cavity size of (4-methylbenzo-15-crown-5) than the other lanthanides. The extraction of thorium(IV) and uranium(IV, VI) by some crown ethers from nitric, hydrochloric and picric acid solutins have been studied. In nitric acid media, thorium(IV) forms a 1∶2 complex with DC18C6 or DC24C8, resembling plutonium(IV) and neptunium(IV) (identification of these reagents is given in Table 1 and Fig. 1). In hydrochloric acid media, the extraction of uranium(IV, VI) leads to a large loading and may be suitable for practical application. The far infrared spectra of the extracted complex in 1,2-dichloroethane have been examined for the UO2Cl2−DCI8C6, UO2Cl2−DC24C8, Th(NO3)4−DC18C6 and Th (NO3)4−DC24C8 systems. The spectra show the existence of direct bonding between the extracted metal ion and the oxygen donor in the ring of these crown ethers.

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Abstract  

The kinetics of99mTc-d, 1-HMPAO decomposition is studied using home kits. The results showed that99mTc-d, 1-HMPAO decomposition is a first-order reaction. The decomposition constant k is found to be 0.017±0.007h–1 under the experimental conditions of 20°C, 185MBq/ml, pH 7.0. The stability of99mTc-d, 1-HMPAO is affected not only by pH and radioactive concentration, but also by temperature. Using Immol/l gentisic acid as a stabilizer, 740MBq/ml of99mTc-d, 1-HMPAO can be stabilized for 3h with the radiochemical purity above 80%.

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Summary  

The organometallic precursor fac-[99mTc(CO)3(H2O)3]+ was reacted with N-ethoxy, N-ethyl dithiocarbamate (NOET) in phosphate buffered saline (pH 7.4) at room temperature for 30 minutes to produce the 99mTc(CO)3-NOET complex. The radiochemical purity (RCP) of the product was over 90% as measured by thin layer chromatography (TLC). No decomposition of the complex at room temperature (RT) was observed over a period of 6 hours. Its partition coefficient indicated that it was a lipophilic complex. The biodistribution comparison in mice of the 99mTc(CO)3-NOET complex and the 99mTcN-NOET complex showed that the former had a lower heart and brain uptake as compared to that of the latter, suggesting the incorporation of the [99mTc(CO)3]+ core into the NOET ligand does not improve the biological features as a myocardial imaging agent.

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For the purpose of qualitative and quantitative analysis of flavonoids from eight species of Indocalamus, Indocalamus latifolius (Keng) McClure, I. herklotsii McClure, I. decorus Q. H. Dai, I. barbatus McClure, I. sinicus (Hance) Nakai, I. longiauritus Hand.—Mazz, I. guangdongensis H. R. Zhao et Y. L. Yang, I. pedalis (Keng) Keng f., a simple, efficient, accurate and low-cost method was constructed. Six flavonoids, vitexin, isovitexin, orientin, isoorientin, quercetin and tricin, were selected as marker flavonoids. The multistage development was performed in Automated Multiple Development (AMD2) and solvents in different ratios were used as mobile phase. The developed plates were scanned by TLC Scanner3. The components separated well and R F values of the six marker flavonoids were 0.22, 0.31, 0.38, 0.45, 0.57, and 0.88, respectively. The method was validated for precision, accuracy, selectivity and repeatability, which were expressed as coefficient of variation (CV [%]). The concentrations and kinds of flavonoids were significantly different in these six species of Indocalamus. The concentration of total flavonoids in the dry leaves was in the range of 0.11–0.40%, and the decreasing order of concentration was I. barbatus, I. sinicus, I. longiauritus, I. guangdongensis, I. decorus, I. pedalis, I. latifolius, I. herklotsii; the concentration of total flavonoids in I. barbatus was the maximum among these eight species of Indocalamus, and they would be more useful in extracting natural bamboo flavonoids.

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Abstract  

Four complexes of rare earth bromides with amino acids, REBr3·3L·3H2O (RE=La, Nd;L=glycine or alanine) were prepared and characterized by means of chemical analysis, elemental analysis, molar conductivity, thermogravimetry, IR spectra and X-ray diffraction. Their thermal decomposition kinetics from ambient temperature to 500°C were studied by means of TG-DTG techniques under non-isothermal conditions. The kinetic parameters (activation energyE and pre-exponential constantA) and the most probable mechanisms of thermal decomposition were obtained by using combined differential and integral methods. The thermal decomposition processes of these complexes are distinguished as being of two different types, depending mainly on the nature of the amino acid.

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Abstract

Thermal decomposition of N,N′-diphenylguanidine (DPG) was investigated by simultaneous TG/DSC-FTIR techniques under nonisothermal conditions. Online FTIR measurements illustrate that aniline is a major product of DPG decomposition. The observation that the activation energy depends on the extent of conversion indicates that the DPG decomposition kinetics features multiple processes. The initial elimination of aniline from DPG involves two pathways because of the isomerization of DPG. Mass spectrometry and thin film chromatography suggest that there are two major intermediate products with the major one of C21N3H17. The most probable kinetic model deduced through multivariate nonlinear regression method agrees well with the experimental data with a correlation coefficient of 0.9998. The temperature-independent function of conversion f(α), activation energy E and the pre-exponential factor A of DPG decomposition was also established through model-fitting method in this research.

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