The dehydration process of Co(II), Cu(II)
and Zn(II) methanesulfonates was studied by thermogravimetry/derivative thermogravimetry
(TG/DTG) and differential scanning calorimetry (DSC) techniques in dynamic
N2 atmosphere. The TG/DTG curves show that all of them
contain four crystallization water molecules, which are lost in two steps.
The peak temperature and dehydration enthalpies ΔH
were measured from DSC curves for each compound. The effect of procedural
variables on the TG and DSC curves was investigated. In this work, the procedural
variables included heating rate, Al pan state (unsealed and sealed) and sample
This study investigated the influences of drying method (oven-, freeze-, and shade-drying) and extraction solvent (ethanol and water) on the bioactivities of Cirsium setidens. Antioxidant activity was evaluated by DPPH radical scavenging ability, anti-diabetic activity was determined by the inhibitory activity of two enzymes: α-glucosidase and α-amylase, while anti-proliferation activity was assessed by MTT assay of three human cancer cell lines (KB, A549, and PC-3). Results indicated that bioactivities were extremely affected by solvent; water extracts contained more phenolics, exhibited strong anti-diabetic effect, but no activity of anti-proliferation, while the ethanolic extracts rich in flavonoids showed profound DPPH radical scavenging and anti-proliferation ability, yet low activity of antidiabetes. Among the drying methods, freeze-drying extracts preserved more flavonoids and exhibited better activity of anti-proliferation, while shade-drying extracts contained higher phenolics and showed stronger activity on antidiabetes, oven-drying gave the lowest content of phenolics. Hence, antioxidant and anti-diabetic effects were positively related to phenolic content, meanwhile an extremely significant correlation coefficient had been found between anti-proliferation activity and flavonoid content, it can be concluded that drying method and extraction solvent affect bioactivities by phenolic and flavonoid contents.
As a new form of traditional Chinese medicine (TCM), Zuojin pill extract is made containing Coptidis rhizoma (the rhizome of Coptis chinesis Franch. [Ranunculaceae]) and Euodiae fructus (the unripe fruit of Euodia rutaecarpa [Juss.] Benth. [Rutaceae]) at the ratio of 6:1 (w/w) and has been most widely used in TCM to treat gastro-intestinal disorders. However, the quality control is insufficient. For establishing an analysis method for the effective quality control of Zuojin pill extract, the active components of three protoberberine alkaloids (coptisine, palmatine, berberine, components from C. rhizoma) and two indolequinoline alkaloids (evodiamine, rutaecarpine, components from E. fructus) in Zuojin pill extract were determined simultaneously by high-performance liquid chromatography. Chromatographic separations were performed on an Inertsil ODS-3 column (4.6 mm × 250 mm, 5 μm). Elution was carried out at 25°C under isocratic conditions by using 25 mmol L−1 KH2PO4-25 mmol L−1 SDS-acetonitrile (1:1:2, v/v/v, adjusted pH to 3.0 using phosphoric acid) as a mobile phase with a flow rate of 0.5 mL min−1. Detection wavelength was set at 264 nm. Good linearity was obtained with correlation coefficient higher than 0.999 for all the analytes over the investigated concentration ranges. Three batches of Zuojin pill extract were successfully analyzed. The average percentages of coptisine, palmatine, berberine, evodiamine, and rutaecarpine in Zuojin pill extract were 5.35%, 3.92%, 16.64%, 0.03%, and 0.03%, respectively. Consequently, these protoberberine and indolequinoline alkaloids could be identified and determined easily by the established high-performance liquid chromatography (HPLC) method which can be used to evaluate and control the quality of Zuojin pill extract.
The thermal decompositions of dehydrated or anhydrous bivalent transition metal (Mn, Fe, Co, Ni, Cu, Zn, Cd) and alkali rare
metal (Mg, Ca, Sr, Ba) methanesulfonates were studied by TG/DTG, IR and XRD techniques in dynamic Air at 250–850 °C. The initial
decomposition temperatures were calculated from TG curves for each compound, which show the onsets of mass loss of methanesulfonates
were above 400 °C. For transition metal methanesulfonates, the pyrolysis products at 850 °C were metal oxides. For alkali
rare metal methanesulfonates, the pyrolysis products at 850 °C of Sr and Ba methanesulfonates were sulphates, while those
of Mg and Ca methanesulfonate were mixtures of sulphate and oxide.
The refinement of unsaturated fatty acids (UFA) from Hippophae rhamnoides L. seed oil was carried out by molecular distillation (MD) using response surface methodology (RSM). A central composite rotate design was used in order to optimize the experimental parameters: distilling temperature and feed flow. The optimal MD conditions were determined and the quadratic response surfaces were drawn from the mathematical models. The results suggested that the distilling temperature and feed flow significantly affected both the UFA content and oil yield in the two models. The optimum conditions for refining UFA were: distilling temperature 107.5 °C and feed flow 1 ml min−1. Optimal values predicted by RSM for the UFA content and oil yield were 82.38% and 62.59%, respectively. Close agreement between experimental and predicted values was obtained.
Authors:D. Lin, H. Wang, M. Lin, M. Lin, and Y. Wu
Adding a magnetic field gradient to the conventional TG system constructs the magnetic thermogravimetry analysis (TG(M) i.e. Faraday methods) and the magnetic derivative thermogravimetry (DTG(M)) techniques. We used the techniques to study the nanocrystalline processes of the FeCuNbSiB and FeCuNbCoSiB amorphous alloys. Some problems of their applications such as the characteristic temperature Tmin and TC are also discussed in detail.
Authors:X. Li, G. Matuschek, M. Herrera, H. Wang, and A. Kettrup
TA/MS (thermal analysis coupled with mass spectrometry) was applied to the pyrolysis of Chinese coals with different ranks.
A total of 13 Chinese coals were investigated. The samples were deliberately chosen to represent the 13 types of Chinese coals
according to the Chinese coal classification system. The experiments were carried out in an argon atmosphere with a flow rate
of 150 ml min-1. The samples were heated from 40 up to 1200C with a constant heating rate of 10 k min-1. The main evolved pyrolysis products were identified through the on-line recorded mass spectra. The thermal and evolution
behavior was compared between the coals. The results showed a strong thermal and evaluation behavior dependence on the coal
rank. Different aliphatic fragments and also some aromatic substances, which are of environmental concern (BTX, PAHs), were
found to be released depending on the different types of coal.
The complex of [Tb2(o-MBA)6(PHEN)2] (o-MBA: o-methylbenzoate and PHEN:1,10-phenanthroline) were synthesized and characterized by elemental analysis and IR spectroscopy.
The thermal behavior of [Tb2(o-MBA)6(PHEN)2] in dynamic nitrogen atmosphere was investigated by TG-DTG techniques. The thermal decomposition process of the [Tb2(o-MBA)6(PHEN)2] occurred in three consecutive stages at Tp 294, 427 and 512C. The kinetic parameters and mechanisms of first decomposition stage from analysis of the TG-DTG curves
were obtained by the Malek method.
Authors:K. Itaka, H. Minami, H. Kawaji, Q. Wang, J. Nishii, M. Kawasaki, and H. Koinuma
We have developed a multi-channel measurement system for combinatorial investigation of thermoelectric materials. The measurement
apparatus has ten series of pin-probe array which enables us to measure the Seebeck coefficient and electric conductivity
of 10 samples simultaneously. A successful measurement on a composition-spread thin films library indicated that this measurement
system is highly useful for the high-speed exploration of thermoelectric materials by combinatorial approach.