Authors:San-Ping Chen, Na Li, Qing Wei, and Sheng-Li Gao
A novel complex [Ni(H2O)4(TO)2](NO3)2·2H2O (TO = 1,2,4-triazole-5-one) was synthesized and structurally characterized by X-ray crystal diffraction analysis. The decomposition
reaction kinetic of the complex was studied using TG-DTG. A multiple heating rate method was utilized to determine the apparent
activation energy (Ea) and pre-exponential constant (A) of the former two decomposition stages, and the values are 109.2 kJ mol−1, 1013.80 s−1; 108.0 kJ mol−1, 1023.23 s−1, respectively. The critical temperature of thermal explosion, the entropy of activation (ΔS≠), enthalpy of activation (ΔH≠) and the free energy of activation (ΔG≠) of the initial two decomposition stages of the complex were also calculated. The standard enthalpy of formation of the new
complex was determined as being −1464.55 ± 1.70 kJ mol−1 by a rotating-bomb calorimeter.
Authors:Jianxi Zhu, Wei Shen, Yuehong Ma, Lingya Ma, Qing Zhou, Peng Yuan, Dong Liu, and Hongping He
Organically modified clay minerals with high thermal stability are critical for synthesis and processing of clay-based nanocomposites. Two series of organo-montmorillonites have been synthesized using surfactants with different alkyl chain length. The organo-montmorillonites were characterized by X-ray diffraction and differential thermogravimetry, combining with molecule modelling. For surfactant with relatively short alkyl chain, the resultant organo-montmorillonite displays a small maximum basal spacing (ca. 1.5 nm) and most surfactants intercalate into montmorillonite interlayer spaces as cations with a small amount of surfactant molecules loaded in the interparticle pores with “house-of-cards” structure. However, for surfactant with relatively long alkyl chain, the resultant organo-montmorillonite displays a large maximum basal spacing (ca. 4.1 nm) and the loaded surfactants exist in three formats: intercalated surfactant cations, intercalated surfactant molecules (ionic pairs), and surfactant molecules in interparticle pores. The surfactant molecules (ionic pairs) in interparticle pores and interlayer spaces will be evaporated around the evaporation temperature of the neat surfactant while the intercalated surfactant cations will be evaporated/decomposed at higher temperature.
Six lanthanide compounds [Ln(H2O)9](m-BDTH)3·9(H2O) where Ln = La (1), and [Ln(H2O)8](m-BDTH)3·9(H2O) (m-BDTH2 = 1,3-benzeneditetrazol-5-yl) where Ln = Lu (2), Yb (3), Er (4), Ho (5) and Y (6) were hydrothermally synthesized and characterized by elemental analyses, infrared spectra, powder X-ray diffraction (PXRD) and X-ray single crystal diffraction. PXRD indicates that 2–6 are isomorphous. Structural analyses reveal that 1 is coordinated by nine water molecules forming a capped-square antiprism, while 2–6 are coordinated by eight water molecules forming a simple square antiprismatic geometry. Effects of water molecules on thermal stability were also discussed by thermogravimetric (TG), DSC, and PXRD under different temperatures. TG analyses suggest that 1 loses lattice and coordinated water molecules with no diacritical boundary, and 6 removes lattice water molecules first and then coordinated water molecules. DSC and PXRD further confirm the consequence.
Authors:Y. Hui-Mei, L. Chang-Wei, Q. Ling-Jun, X. Hua-Qing, X. Tong-Geng, and L. Lan
We studied the removal process of excessive free
carbon in the nano-SiC powder by TG-DTA-MS, XRD and TEM three methods. The
studies showed that the temperature of removing excessive free carbon in the
nano-SiC powder should be about 750°C in air.
Authors:Haichao Zhan, Zhen Wei, Ke Ren, Shuhua Tong, Xianqin Wang, and Qing Wu
Isocorynoxeine is one of the main alkaloids in Chinese medicinal herbs, and has pharmacological activities such as antihypertensive, sedative, anticonvulsant, and neuronal protection. It is an effective component of Uncaria for the treatment of hypertension. In this study, we used a fast and sensitive ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) to detect isocorynoxeine in rat plasma and investigated its pharmacokinetics in rats. Six rats were given isocorynoxeine (15 mg/kg) by intraperitoneal (i.p.) administration. Blood (100 μL) was withdrawn from the caudal vein at 5 and 30 min and 1, 2, 4, 6, 8, 12, and 24 h after administration. Chromatographic separation was achieved using a UPLC BEH C18 column using a mobile phase of acetonitrile–0.1% formic acid with gradient elution. Electrospray ionization (ESI) tandem mass spectrometry in the multiple reaction monitoring (MRM) mode with positive ionization was applied. Intra-day and inter-day precisions (relative standard deviation, %RSD) of isocorynoxeine in rat plasma were lower than 12%. The method was successfully applied in the pharmacokinetics of isocorynoxeine in rats after intraperitoneal administration. The t1/2 of isocorynoxeine is 4.9 ± 2.1 h, which indicates quick elimination.
While in situ TLC/FTIR technique has tremendous potential in the analysis of complex mixtures, the conventional stationary phase, such as silica gel, used for TLC/FTIR analysis, has strong absorption in IR region and thus brings about severe interference in the obtained FTIR spectra of the separated samples. In this work, we propose to use lanthanum fluoride fine particles as a new stationary phase of a TLC plate. The average size of LaF3 particles is around 100 nm. FTIR spectrum of the LaF3 particles has no interfering absorption. Preliminary TLC experiments show that mixtures of rhodamine B and methylene blue mixture can be successfully separated by this new TLC plate using LaF3 fine particles as a stationary phase. Methylene blue and rhodamine B from separated spot can be clearly detected by using in situ FTIR spectra.
Authors:Guan-Quan Wang, Ji Zhang, Shun-Zhong Luo, Na Wang, Hong-Yuan Wei, Wen-Jin Wang, Yu-Qing Yang, Guo-Ping Liu, and Xiao-Qi Yu
A new nitrido-188Re complex, 188ReN-NEMPTDD, was synthesized through a modified method in high yield. This complex was stable in vitro. The biodistribution
in normal mice showed that this ReN complex accumulated in the liver and was eliminated quickly from almost all organs. VX2
carcinoma was grown in the livers of rabbits. Transcatheter arterial embolization (TAE) was performed using 188ReN-NEMPTDD/lipiodol solution. The SPECT images showed that the lipiodol solution could be concentrated in the tumor for about
12 hours. These results indicated that 188ReN-NEMPTDD/lipiodol could be a potential radiopharmaceutical for liver cancer.
Authors:Hai-Qing Zhang, Bang-Fa Ni, Wei-Zhi Tian, Gui-Ying Zhang, Dong-Hui Huang, Cun-Xiong Liu, Cai-Jin Xiao, Peng Nie, and Hong-Chao Sun
An expression of γ-ray efficiency for large samples is proposed based on numerical integration of efficiencies over compositional
point sources. The widely used expression on radial variation of HPGe efficiency for point source originally proposed by Noguchi
et al. (Int J Appl Radiat Isot 32:17–22, 1980 [<cite>1</cite>]) was amended and a new expression was proposed. A comparison between the two expressions indicates that the newly proposed
expression brings about an obvious improvement, and Self-absorption correction for a voluminous source is also given out by
using the EID principle. The functional relationship between HPGe efficiency for γ-rays from a point source and the spatial
position of the source was established. The results of this study can be applied in order to determine γ attenuation effects
of unknown bulky samples with various shapes and materials.
Twenty different brands of Chinese tea were analyzed for multiple trace elements, including some essential and toxic elements,
by neutron activation analysis (NAA). A comparison among tea brands from China, India, US and other countries was made for
the ranges and averages of concentrations for Na, K, Mn, Cu, and Br. It has been observed that the trace element contents
in tea leaves are largely dependent upon the soil and the environment where the tea grows. Chinese tea is rich in Mn and Cu
comparing with those of other counties surveyed, but is indigent in Na. The transference ratio for each element determined
(i.e., the fraction of an element in tea leave transferred into solution when tea is leached by percolation) is also reported.
Adult daily intakes of some essential and toxic elements from tea drinking were also estimated.