Extracts from lo-han-kuo (Siraitia grosvenorii) are of high sweetness and low calories, and they have been widely used as a natural sweetener to reduce the risk of obesity and diabetes. In the current study, lo-han-kuo extracts were extracted using subcritical water under different operation condition. The study revealed that the optimal extracting parameters were: extraction time of 20 min, extraction temperature of 140 °C, and the addition of 15% ethanol. Antioxidant activity, contents of total flavonoids, and total phenolic compounds of lo-han-kuo extracts were also investigated. A mathematical model was established to describe the relationship between antioxidant capacity and content of bioactive components in lo-han-kuo extract, and it was found that antioxidant capacity of the extracts was mainly attributed to the yields of total mogrosides (P<0.05).
We construct with a differential scanning calorimeter (DSC) a phase diagram for the ethylene carbonate (EC)-dimethyl carbonate
(DMC) binary system for its liquid-solid phase equilibria. We determine the eutectic composition of the binary system using
an enthalpic method that we devised based on the composition dependence of the enthalpy of solidus melting, with highly consistent
results. We also discuss the merits and limitations of this enthalpic method.
Polyvinyl chloride (PVC)/organic-montmorillonite composites were prepared by melt intercalation. Their structures and properties
were investigated with X-ray diffraction (XRD), differential scanning calorimetry (DSC) and mechanical testing. The results
showed that PVC chains could be intercalated into the gallery of organically modified montmorillonite to form exfoliated PVC/organic-montmorillonite
nanocomposites, and the glass transition temperatures of PVC/organic-montmorillonite composites were lower than that of neat
PVC. However, the tensile strength, and both the Izod type and Charpy notched impact strengths of PVC/organic-montmorillonite
nanocomposites were fitted with the linear expressions: t=535.07-6.39Tg, sI=378.76-4.59Tg and sC=276.29-3.59Tg, respectively.
Authors:A. Yakushev, S. Timokhin, M. Vedeneev, Xu Honggui, and I. Zvara
An isotope of element 106, namely263106, detected by its spontaneous fission, has been chemically isolated by thermochromatography of oxochlorides. The last one has been compared with short- and long-lived isotopes of Mo and W. Two chemical species were observed, presumably MO2Cl2 and MOCl4 (M=Mo,W). A kinetic dependence of these two species has been discussed and a chemical form O2Cl2 has been described for the registered atoms of element 106.
Authors:X. Zheng, T. Kawae, S. Tanaka, M. Suzuki, and C. Xu
Heat capacity measurements were carried out on single-crystalline CuO in the temperature range 130–300 K. Sharp peaks corresponding to the antiferromagnetic transitions were clearly observed at 211 and 227 K. At the low-temperature end, near 160 K, a wide peak in the heat capacity signal was also demonstrated. An electric anomaly was observed in the temperature range 150–160 K, which strongly suggests the possibility of a new low-temperature phase transition in CuO. This study also indicates that DSC measurement is an effective tool to detect magnetic transitions and probe subtle phase transitions in solids.
Supramolecular 2,3- and 2,5-pyridinedicarboxylate (PDC) intercalated
ZnAl-layered double hydroxides (2,3- and 2,5-PDC–ZnAl–LDHs) have
been prepared by ion exchange method. The structure and composition of the
intercalated materials have been studied by X-ray diffraction (XRD) and inductively
coupled plasma emission spectroscopy (ICP). The study indicates that the 2,3-PDC
and 2,5-PDC anions are accommodated as interdigitated bilayer and monolayer
arrangement respectively between the sheets of LDHs. Furthermore, their thermal
decomposition processes were studied by the use of in situ high temperature
X-ray diffraction (HT-XRD), and the combined technique of thermogravimetry-differential
thermal analysis-mass spectrometry (TG-DTA-MS) under N2 atmosphere. Based
on the comparison study on the temperatures of both decarboxylation and complete
decomposition of interlayer PDC, it can be concluded that 2,5-PDC–ZnAl–LDHs
has higher thermal stability than that of 2,3-PDC–ZnAl–LDHs.
Authors:N. He, D. Li, M. Tu, J. Shen, S. Bao, and Q. Xu
The acidity of mesoporous materials FeSiMCM-41, LaSiMCM-41, SiMCM-41, AlSiMCM-41 and HAlSiMCM-41 has been investigated by microcalorimetric studies of the adsorption of ammonia and temperature programmed ammonia desorption method. In the initial stage, the acid strength sequence is SiMCM-41>HAlSiMCM-41>AlSiMCM-41>FeSiMCM-41>LaSiMCM-41, in agreement with that found for microporous molecular sieves materials. A small number of strong acid sites of SiMCM-41 may result from the aluminum impurity contained in the silica source material. The acid density sequence is HAlSiMCM-41>AlSiMCM-41>FeSiMCM-41>LaSiMCM-41SiMCM-41 and can be explained by the studies of existing states of trivalent atoms in these samples reported in previous work. Since some NH3-TPD plots of these samples show the profiles that could not be back to baseline at elevated temperature, the technique of microcalorimetric adsorption is preferable in studying these samples.
Authors:L. Wang, Z. Zhang, H. Liu, S. Xu, M. He, H. Liu, O. Veisz, and Z. Xin
Stripe rust, caused by
(PST), is one of the most serious diseases of wheat (
L.) worldwide. Of 94
Triticum durum/Aegilops tauschii
synthetic wheat accessions tested, CI142 (Garza/Boy//
271) was found to be resistant to 6 Chinese PST races. The resistance to stripe rust in CI142 was proven to be controlled by a single dominant gene, tentatively designated
. Gene postulation showed that the pathogenic specificity of CI142 is different from 21 other lines possessing known resistance genes, such as
Yr10, Yr15, Yr24
, located on chromosome 1B. Bulked segregant analysis (BSA) and F
segregation analysis of the CI142/Mingxian 169 cross were used to analyse the SSR markers linked to
. Five SSR markers were found to be closely associated with
in the order
, in which the relative genetic distances of these SSR loci to the gene
were 5.4, 0.8, 0.8, 1.0, and 2.4 cM, respectively. Two SSR markers (
Yr10, Yr15, Yr24
, suggesting that these 2 SSR markers may be used as diagnostic ones for the gene in a wheat breeding program against stripe rust. Based on these findings,
is most likely a new gene or a new allele at the
locus, which provides an opportunity to diversify stripe rust-resistant resources for wheat breeding programs.
Authors:S. Wang, Z. Tan, Y. Di, F. Xu, M. Wang, L. Sun, and T. Zhang
As one primary component of Vitamin B3, nicotinic acid [pyridine 3-carboxylic acid] was synthesized, and calorimetric study and thermal analysis for this compound
were performed. The low-temperature heat capacity of nicotinic acid was measured with a precise automated adiabatic calorimeter
over the temperature rang from 79 to 368 K. No thermal anomaly or phase transition was observed in this temperature range.
A solid-to-solid transition at Ttrs=451.4 K, a solid-to-liquid transition at Tfus=509.1 K and a thermal decomposition at Td=538.8 K were found through the DSC and TG-DTG techniques. The molar enthalpies of these transitions were determined to be
ΔtrsHm=0.81 kJ mol-1, ΔfusHm=27.57 kJ mol-1 and ΔdHm=62.38 kJ mol-1, respectively, by the integrals of the peak areas of the DSC curves.