Authors:Jun Zhang, Shuangjun Chen, Jun Su, Xuming Shi, Jing Jin, Xiaolin Wang, and Zhongzi Xu
Non-isothermal crystallization kinetics and subsequent melting behavior for three kinds of ethylene-acrylic acid copolymer
(EAA) are investigated via differential scanning calorimetry (DSC). From the Jeziorny method, the crystallization rate of
the primary stage is significantly influenced by the competitive mobility of chains. While the crystallization rate in the
secondary stage decreases in order of acrylic acid (AA) content in copolymers. Mo’s method can also provide a good fitting.
Difference between the Jeziorny method and Mo’s method analysis is because of a higher effect of non-crystallizable chain
ends. The effective activation energy is also determined via Kissinger’s method.
Authors:Chen Xu, Jingqi Guan, Shujie Wu, Mingjun Jia, Tonghao Wu, and Qiubin Kan
ITQ-13, a tridirectional medium-pore zeolite containing 9- and 10-member-ring pores, has been successfully synthesized by
a hydrothermal method. The catalytic performance of Mo-ITQ-13 is worse than with Mo-ZSM-5 in the methane aromatization reaction.
It has been shown that 9-member-ring channels favor coke and are a disadvantage in methane non-oxidative aromatization.
Authors:Kang-Zhen Xu, Yong-Shun Chen, Min Wang, Jin-An Luo, Ji-Rong Song, Feng-Qi Zhao, and Rong-Zu Hu
A novel energetic material, 4,5-dihydroxyl-2-(dinitromethylene)-imidazolidine (DDNI), was synthesized by the reaction of FOX-7 and glyoxal in water at 70 °C. Thermal behavior of DDNI was studied with DSC and TG-DTG methods, and presents only an intense exothermic decomposition process. The apparent activation energy and pre-exponential factor of the decomposition reaction were 286.0 kJ mol−1 and 1031.16 s−1, respectively. The critical temperature of thermal explosion of DDNI is 183.78 °C. Specific heat capacity of DDNI was studied with micro-DSC method and theoretical calculation method, and the molar heat capacity is 217.76 J mol−1 K−1 at 298.15 K. The adiabatic time-to-explosion was also calculated to be a certain value between 14.54 and 16.34 s. DDNI presents lower thermal stability, for its two ortho-hydroxyl groups, and its thermal decomposition process becomes quite intense.
Authors:Z. Xiao, D. Liu, C. Wang, Z. Cao, X. Zhan, Z. Yin, Q. Chen, H. Liu, F. Xu, and L. Sun
The effect of mechanical alloying on Zn-Sb alloy system is investigated with X-ray diffraction (XRD), laser grain size analysis
and differential scanning calorimetry (DSC) respectively. The results of laser particle size analysis shows that the particle
size decreases with increasing of the grinding time between 0 and 24 h. XRD and DSC results indicate that longer the grinding
time of Zn-Sb is, the more content of Zn4Sb3 become in the product in this process.
Authors:D. Xu, Q. L. Ning, X. Zhou, C. L. Chen, X. L. Tan, A. D. Wu, and X. Wang
Effects of ionic strength and of fulvic acid on the sorption of Eu(III) on alumina were investigated by using a batch technique.
The experiments were carried out at T=25±1 °C, pH 4-6 and in the presence of 1M NaCl. The results indicate that sorption isotherms of Eu(III) are linear at low
pH values. The sorption-desorption of Eu(III) on alumina at pH 4.4 is reversible, but a sorption-desorption hysteresis is
found at pH 5.0. Fulvic acid has an obvious positive effect on the sorption of Eu(III) on alumina at low pH values. The migration
of Eu(III) in alumina was studied by using column experiments and 152+154Eu(III) radiotracer at pH 3.8. For column experiments, Eu(III) sorbed on alumina can be desorbed completely from the solid
surface at low pH values. The findings are relevant to the evaluation of lanthanide and actinide ions in the environment.
Authors:F. Xu, L. Sun, P. Chen, Y. Qi, J. Zhang, J. Zhao, Y. Liu, L. Zhang, Zhong Cao, D. Yang, J. Zeng, and Y. Du
The heat capacities of LiNH2 and Li2MgN2H2 were measured by a modulated differential scanning calorimetry (MDSC) over the temperature range from 223 to 473 K for the
first time. The value of heat capacity of LiNH2 is bigger than that of Li2MgN2H2 from 223 to 473 K. The thermodynamic parameters such as enthalpy (H–H298.15) and entropy (S–S298.15) versus 298.15 K were calculated based on the above heat capacities. The thermal stabilities of them were investigated by
thermogravimetric analysis (TG) at a heating rate of 10 K min−1 with Ar gas flow rate of 30 mL min−1 from room temperature to 1,080 K. TG curves showed that the thermal decomposition of them occurred in two stages. The order
of thermal stability of them is: Li2MgN2H2 > LiNH2. The results indicate that addition of Mg increases the thermal stability of Li–N–H system and decrease the value of heat
capacities of Li–N–H system.
Galangin (GAL), the major bioactive flavonol extracted from Alpinia officinarum Hance (Zingiberaceae), has attracted much attention due to its multiple biological activities. To develop a fast, reliable, and sensitive ultrahigh-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) method for the quantification of GAL in rat plasma and mouse tissues. UHPLC–MS/MS using electrospray ionization operating in negative-ion mode was used to determinate GAL in 18 rats receiving three doses of GAL (2 and 9 mg/kg by intravenous injection, 5 mg/kg by oral administration), with six rats for each dose. Blood samples were collected at 0.0333, 0.25, 0.5, 1, 2, 4, 6 and 8 h. A total of 25 mice received 18 mg/kg GAL by intraperitoneal injection. Liver, heart, lung, spleen, brain, and kidney tissue samples were collected at 0.25, 0.5, 2, 4, and 6 h. The precision of the method was better than 12.1%, while the accuracy ranged from −4.8% to 8.1%. The results of pharmacokinetics demonstrated rapid GAL absorption (tmax of 0.25 h), fast elimination (t1/2 <1.1 h) after three different dosages, and an absolute bioavailability of ~7.6%. Tissue distribution analysis revealed abundant GAL in liver, kidney, spleen, and lung and smaller amounts in brain. The developed method proved fast (3 min), efficient, and reliable, with high selectivity for the quantitative analysis of GAL in biological samples. This is the first study to identify the target tissues of GAL, and the results may help to elucidate the mechanisms underlying its therapeutic effects in vivo.
Authors:Genquan Yan, Lu Yu, Xu Chen, Triet Tran, Lam Nguyen, Zhijun Wang, and Ling Wang
A rapid and sensitive High-Performance Liquid Chromatography-tandem Mass Spectrometry (HPLC/MS/MS) method for determining apremilast in beagle dog plasma and urine samples was developed and validated using clopidogrel as the internal standard (IS). Apremilast was extracted from the plasma and urine samples by liquid–liquid extraction using methyl tert-butyl ether. Chromatographic separation was performed using a C8 column with gradient elution and a mobile phase containing methanol and 0.1% formic acid. Quantification was achieved in multiple reaction monitoring (MRM) mode with a transition of m/z 461.3→178.2 for apremilast and m/z 322.2→184.1 for clopidogrel (IS). This method was validated regarding its specificity, linearity, precision, accuracy, and stability. The lower limit of quantification (LLOQ) for this method was 5 ng/mL, and the calibration curve was linear over 5–1,000 ng/mL. The intra- and inter-run coefficients of variance (CV) of aprelimast in plasma samples were less than 12.92% and 10.64%, respectively, while in urine samples, the CV were less than 11.84% and 10.20%, respectively. The samples were stable under the tested conditions. This method was successfully applied to a pharmacokinetic study in beagle dogs following oral administration of 10 mg of apremilast.
3-(4-[18F]fluorobenzyl)-8-hydroxy-1,2,3,4-tetrahydrochromeno[3,4-c]pyridin-5-one ([18F]FHTP) was in vitro and in vivo evaluated as a putative dopamine D4 receptor radioligand. Its inhibition constant (Ki) for cloned human dopamine D4.2 receptor was determined to be 2.9 nM and it displayed a 2000-fold D4-selectivity over the D2long subtype. Its partition coefficient (logP) was measured to be 1.11. Biodistribution, blocking distribution and metabolism studies in rats demonstrated that the specific
distribution of [18F]FHTP in brain regions, suggesting that [18F]FHTP may be a suitable PET imaging agent for in vivo studies of the dopamine D4 receptor.
Authors:Chuan-Min Qi, Yong He, Xiao Wang, Man Feng, Jing-Li Xu, Rui Ding, Hang Liu, Yu-Rong Chen, Fang Li, Zhao-Hui Zhu, Yong-Hong Dang, Shu-Ting Zhang, and Ying Xie
d-glucosamine at concentration of certain range could kill tumor cells without influencing normal cells. There are also some
reports on the antitumor activity of d-glucosamine and its derivatives in murine models. It was therefore postulated that d-glucosamine might have the potential to invade tumor cells. We designed and radiosynthesized a glucosamine derivative, N-(2-[18F]fluoro-4-nitrobenzoyl)glucosamine ([18F]FNBG([18F]7)). Evaluations in vitro and in vivo were performed on tumor bearing mice. Excitingly, the radiochemical purity of [18F]FNBG([18F]7) was 99%, and besides the best radiochemical yield was up to 35%. The best T/Bl (Tumor/Blood) and T/M (Tumor/Muscle) ratios
of [18F]FNBG([18F]7) were 4.40 and 4.84. Although [18F]FNBG([18F]7) deserved further studies, the results revealed it might become a potential PET imaging agent for detecting tumors.