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  • Author or Editor: Li Xu x
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Abstract  

Differential elastic scattering cross sections for backscattering of 0.96–2.74 MeV protons incident on an aluminum layer covered by a gold layer deposited on a graphite crystal have been measured. The lowest proton energy in the experiment is in the Rutherford backscattering energy region. The measured cross sections are compared with the previous data and presented in graphical and tabular forms.

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Abstract

A novel acrylonitrile-capped poly(propylene imine) dendrimer (PAN4) was synthesized and characterized with FTIR and 1H-NMR. PAN4 and its precursor (poly(propylene imine) dendrimer (1.0GPPI) were employed to cure bisphenol A epoxy resin (DGEBA), and the nonisothermal reaction kinetics of DGEBA/PAN4 and DGEBA/1.0GPPI was systematically investigated using a differential scanning calorimeter (DSC) in a comparative way. The apparent activation energies determined with the Kissinger method were 59.7 kJ/mol for DGEBA/1.0GPPI and 53.9 kJ/mol for DGEBA/PAN4. Applied the Málek method, it was found that a two-parameter autocatalytic model (SB(m, n)) could well simulate the reaction rates, and further analysis of the reaction rate constants showed PAN4 could cure DGEBA at a greatly decreased rate by a factor a more than ten compared with 1.0GPPI control.

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Summary

An efficient ionic liquid-based microwave-assisted (IL-MAE) method has been developed for extraction of dehydrocavidine from Corydalis saxicola Bunting (C. saxicola) for subsequent rapid analysis by high-performance liquid chromatography (HPLC). The yield of dehydrocavidine reached 9.446 mg g−1 within 10 min under the optimum IL-MAE conditions (1.5 mol L−1 [hmim]Br as extraction solvent, liquid-to-solid ratio 20:1 (mL:g), and extraction temperature 70°C). Compared with conventional procedures, the proposed IL-MAE method has many advantages, for example high extraction yield, short extraction time, low solvent consumption, no use of volatile organic solvents, and no further sample clean-up before HPLC analysis. The method was validated for limit of detection (LOD) and quantification (LOQ), linearity, precision, recovery, and reproducibility. The calibration range was 5.0–200 mg L−1 and the correlation coefficient, r, was 0.9996. The LOD and LOQ were 0.035 and 0.12 mg L−1, respectively. The relative standard deviations of intra-day and inter-day assays were below 2.6% and 6.5%, respectively. Recovery was between 93.8% and 109.3% with RSD values below 5.0%. The method can be used for rapid and effective extraction and analysis of active components from medicinal plants.

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A continuous-flow reactor (Corning G1 reactor) was hereby introduced for Fischer indole synthesis of 3-methylindole by reaction of phenyl hydrazines and propylaldehyde. Stoichiometric Lewis acid, ZnCl2, was supplied as catalyst as well as remover of NH3 which generated during the indole ring formation. Ionic liquid ([EMIM][BF4]) was employed as solvent according to its high-temperature tolerance and good product distribution. After a straightforward extraction process, 3-methylindole could be obtained in a 95.3% yield (96.0% purity) under optimized conditions. Ionic liquid (IL) was then recovered by another extraction process, and the recovered IL acted nearly as efficiently as new IL for this Fischer indole reaction.

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Abstract  

Chemical behavior of lanthanum in root tips excized from wheat seedlings growing at both promotional and inhibitory levels of LaCl3 in culture solutions was investigated by a sequential leaching procedure combined with instrumental neutron activation analysis. The results indicate that most of La exists in non-exchangeable species and the binding of La3+ to the root tips is extremely stable. The root tips during growing at the inhibitory level of LaCl3 absorb much more La than those at the promotional level. However, the La proportion in each fraction is similar for both groups.

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Abstract  

This study examined the tissues distribution and pharmacokinetics of rhTNT-IL2, a fusion protein, in rats and macaques after iv. injection. The rhTNT-IL2 was labeled with 125I. The 125I-rhTNT-IL2 was administered into rats and macaques at a dose of 250 μg·kg−1 and 125 μg·kg−1, respectively. Upon administration, rhTNT-IL2 declined in tri-exponentially with the half-lives of 1.78 h (T 1/2α), 25.06 h (T 1/2β), 114.19 h (T 1/2γ) for rats and 1.87 h (T 1/2α), 9.82 h (T 1/2β), 43.17 h (T 1/2γ) for macaques. The fraction of 125I-rhTNT-IL2 excreted in feces was low (about 1%), while the majority of 125I-rhTN-IL2 was excreted in urine. The tissue distributions showed that the liver, spleen and heart were major organs for deposition of the fusion protein in rats and macaques in 48-hour post-injection, and the fusion protein could not penetrate through blood brain barrier.

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Abstract  

The molar heat capacities C p,m of 2,2-dimethyl-1,3-propanediol were measured in the temperature range from 78 to 410 K by means of a small sample automated adiabatic calorimeter. A solid-solid and a solid-liquid phase transitions were found at T-314.304 and 402.402 K, respectively, from the experimental C p-T curve. The molar enthalpies and entropies of these transitions were determined to be 14.78 kJ mol−1, 47.01 J K−1 mol for the solid-solid transition and 7.518 kJ mol−1, 18.68 J K−1 mol−1 for the solid-liquid transition, respectively. The dependence of heat capacity on the temperature was fitted to the following polynomial equations with least square method. In the temperature range of 80 to 310 K, C p,m/(J K−1 mol−1)=117.72+58.8022x+3.0964x 2+6.87363x 3−13.922x 4+9.8889x 5+16.195x 6; x=[(T/K)−195]/115. In the temperature range of 325 to 395 K, C p,m/(J K−1 mol−1)=290.74+22.767x−0.6247x 2−0.8716x 3−4.0159x 4−0.2878x 5+1.7244x 6; x=[(T/K)−360]/35. The thermodynamic functions H TH 298.15 and S TS 298.15, were derived from the heat capacity data in the temperature range of 80 to 410 K with an interval of 5 K. The thermostability of the compound was further tested by DSC and TG measurements. The results were in agreement with those obtained by adiabatic calorimetry.

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Journal of Thermal Analysis and Calorimetry
Authors: Jiawu Gao, Lin Li, Yanping Deng, Zongming Gao, Changhua Xu and Mingxi Zhang

Abstract  

A new method for determining the degree of conversion of gelation (αgel) and gel time (t gel) at gel point using a single technology, DSC, is discussed in this work. Four kinds of thermoset resins are evaluated. It is found that the mutation points of reduced reaction rate (V r) vs. reaction conversion (α) curves, corresponding with the changes of reaction mechanism, represents the gelation of the reaction. The α at the mutation point is defined as αgel. From isothermal DSC curves, the point at αgel is defined ast gel. Traditional techniques (ASTM D3532 and DSC method) are also used to determine αgel andt gel in order to demonstrate this new method. We have found that the results obtained from this new method are very consistent with the results obtained from traditional methods.

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Abstract  

23-Hydroxybetulinic acid (23-HBA) is the efficient antitumor compound extracted from the roots of a Chinese Medicinal Herb, Pulsatilla chinensis (Bge) Regel. To evaluate the effect of radioiodination on cytotoxicity, 23-HBA was radioiodinated with 125I. 125I-23-HBA could be prepared in high yields and good radiochemical purity and was characterized using reverse phase HPLC. In ICR mice bearing Liver Cancer HepA tumor, 125I-23-HBA showed a tumor uptake of 2.1% ID/g at 2 h p.i. and 0.15% ID/g at 48 h p.i on i.v. injection. When injected intratumorally, greater tumor uptake and retention was observed (20% ID/g at 2 h p.i. and 4.6% ID/g at 48 h p.i. respectively).

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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.

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