We show that every T1 wN-space is expandable and as a corollary, we prove that a ϑ-refinable sym-wg T1 space is paracompact and thus two problems of Chris Good are solved. We also investigate s-expandability, and for extremally disconnected spaces, a characterization of s-expandability is given in terms of covers, which gives an extension to a known result.
Authors:F. Jiang, S. Lee, S. Bakhtiar, and R. Kuroda
A new procedure for the radiochemical measurements of thorium, uranium and plutonium in atmospheric samples is described. Analysis involves coprecipitation of these actinides with iron hydroxide from a 40-to 50-dm3 sample of rainwater, followed by radiochemical separation and purification procedures by the use of ion exchange chromatography (Dowex AG1×8) and solvent extraction. The new procedure enables one to determine the isotopes of thorium, uranium and plutonium, which are found in rainwater at extremely low concentrations, with a chemical yield ranging from 60 to 80%.
Authors:L. Zhao, J. Ge, C. Qiao, H. Zhang, and S. Jiang
A high-performance liquid chromatographic (HPLC) method has been developed for separation and quantitative analysis of flavonoid aglycones in Rhododendron anthropogonosides Maxim. Flavonoids in their bound forms were hydrolyzed with acid before HPLC analysis. Analytical samples were pretreated by solid-phase extraction on C18 reversed-phase cartridges. Optimum separation on a 4.6 mm × 250 mm i.d. C18 column was achieved by use of a 52:48 (v/v) mixture of methanol and an aqueous solution of 10 mm citric acid and 1 mm sodium dodecyl sulfate as mobile phase. The flow rate was 1.0 mL min–1 and the detection wavelength 360 nm. Five flavonoids, myricetin, quercetin, luteolin, kaempferol, and isorhamnetin, were separated with high resolution without use of gradient elution. The method was successfully used for efficient quality-control analysis by quantifying flavonoids in R. anthopogonosides. Repeatability tests showed that intra-day and inter-day RSD was <10%. LOD of the five flavonoids were <0.85 μg mL–1. Recovery ranged from 90.2 to 112.5%, with RSD <11.1%.
Authors:L. Yu, S. Wang, X. Jiang, N. Wang, and C. Zhang
Combustion experiments of three typical seaweeds (Gracilaria cacalia, Enteromorpha clathrata and Laminaria japonica) have been studied using a DTA-60H Thermal Analyzer and the combustion processes and characteristics are studied. Thermogravimetric
experiments are carried out on the samples with 0.18 mm particle size at the heating rate of 20°C min−1.
The results indicate that the ignition mode of seaweed is homogeneous and the combustion process is composed of dehydration,
the pyrolysis and combustion of volatile, transition stage, the combustion of char as well as the reaction at high temperature.
And the combustion characteristic parameters are obtained such as ignition temperature, maximum rate of combustion, burnout
temperature etc. The combustion models of these seaweeds are also analyzed. The combustion characteristics and model differences
between the seaweed and woody biomass are caused by the differences of volatile components. The combustibility indexes of
seaweeds calculated are better than that of woody biomass, and the index of Gracilaria cacalia is the best. At last, activation energies are determined using Arrhenius model that is solved by binary linear regression
Authors:X. Feng, S. Lo, G. Ji, Y. Jiang, and Y. Xu
The production rates (numbers of atoms per gram of the respective elements per second) of 40 radioactive nuclides of 34 elements by neutron capture reactions in a reactor were determined from about 130 photopeaks of the -ray spectra. The ratios of these production rates were called R-matrix elements. These production rates and the respective thermal neutron capture cross sections were used to calculate the respective apparent neutron fluxes at the position of irradiation and the -matrix elements which were the ratios of these apparent neutron fluxes. These matrix elements express clearly the correlations among various elements and thus may be used in the mono-standard or small-number-standards method in neutron activation analysis.
Authors:B. Zhou, S. Jiang, L. Zou, X. Wang, D. Wang, J. Liu, S. Shang, and D. Zhou
A new compound cyclohexyl-t-butyldimethylammonium tetraphenylborate, [C6H11N(CH3)2(C(CH3)3)]BPh4 has been prepared, and its decomposition mechanism was studied by TG. The IR spectra of the products of thermal decomposition were examined at every stage. Kinetic analysis for the first stage of thermal decomposition process was obtained by TG and DTG curves, and kinetic parameters were obtained from the analysis of the TG-DTG curves with integral and differential equations. The most probable kinetic function was suggested by comparison of kinetic parameters.
Authors:S. Li, L. Liu, H. Jiang, D. Liu, S. Chen, and Z. Yang
The crystal C81H78N12O6Cd3 was synthesized and its structure was determined by single crystal X-ray diffraction method. The complex crystallizes in
the monoclinic system space group P21/n with cell parameters, a=15.959(4) , b=26.222(3) , c=25.907(6) , β=101.60(2). The non-isothermal kinetics of the crystal
was studied by use of non-isothermal TG and DTG curves. The kinetic parameters were analyzed by means of integral and differential
methods, and mechanism functions of the thermal decomposition reaction for its second step were proposed. The kinetic equation
of thermal decomposition is expressed as:
dα/dt=Aexp(-E/RT)1.5(1-α)4/3[1/(1-α)1/3-1]−1. The average values of E(kJ mol−1) and lnA/s−1 are 339.25, 43.95, respectively.
Authors:S. Wang, D. Chen, G. Guo, T. Zhang, S. Jiang, X. Shen, D. Perovic, S. Prodanovic, and Y. Yan
In this work, 9 novel LMW-GS genes (6 LMW-m and 3 LMW-i type) from 4 diploid and 1 tetraploid Aegilops species were amplified and cloned by allelic-specific PCR. Analysis of the deduced amino acid sequences showed that 7 and 2 LMW-GS had 9 and 7 cysteines, respectively. Four LMW-m type subunits genes had an extra cysteine at the C-terminal III, which could form intermolecular disulphide bonds to extend the chains, and therefore would facilitate to form larger gluten polymers. This suggested that these genes are expected to be used as candidate genes for wheat quality improvement. The correlation between specific N-terminal sequences and a decapeptide deletion in the C-terminal II in LMW-GS encoded by D genome was found. Particularly, if LMW-GS possessed a METRCIPG-N-terminal beginning sequences and a decapeptide (LGQCSFQQPQ) deletion in the C-terminal II, they could be encoded by D genome.