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- Author or Editor: Wei Yang x
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Abstract
Combining the Charged Particle Activation Analysis (CPAA) and the Channeling Technique, the partial concentrations of the impurity carbon atoms in different crystal lattice locations of GaAs were claculated. The calculated results show that at lower total concentrations (
0.3 ppm), carbon atoms occupy principally the octahedral and displaced octahedral interstitial positions, but at higher total concentrations (2 ppm), the substitutional carbon plays a principal role.
Abstract
The thermal properties of KTN crystal were investigated at low temperatures by DSC and TM. The phase transition enthalpies and the average specific heats of the crystal were measured. Results are analyzed and discussed.
Abstract
In order to assure the public health, simple and relibable analytical methods must be established for effective surveillance of polluted surface water. Since the pollutants in surface water are usually found at ultratrace levels, preconcentration is generally required to ensure the quality of the analytical results. An analytical procedure consisting of preconcentration using hydrous magnesium oxide followed by neutron activation analysis has been proposed and applied to the determinations of trace elements in surface water.
Abstract
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.
Abstract
A systematic investigation has been carried out on the extractive behavior of N,N'-dihexanoylpiperazine (DHPEZ) with respect to U(VI) in five diluents, from aqueous nitric acid media. The variation of U(VI) distribution ratio with the concentrations of aqueous nitric acid, extractant, salting-out agent and with temperature has been investigated and discussed. The increasing order of extractive ability of DHPEZ towards U(VI) is: chloroform, carbon tetrachloride, 1,4-dimethyl-benzene, toluene, benzene. The composition of the extracted species and extraction constants as well as the enthalpy changes are given.
Porcine epidemic diarrhoea virus (PEDV) is one of the important pathogens that may cause severe diarrhoea in piglets. In this study, the nucleocapsid (N) gene of a Chinese PEDV isolate designated HLJBY was cloned. The phylogeny of PEDV strains was investigated by constructing a phylogenetic tree based on the N protein sequences. The results indicate that there are two major groups of Chinese PEDVs, a Japanese PEDV group and a Korean PEDV group. High-level expression of the N protein was achieved in Escherichia coli. The immunoreactivity between PEDV particles or the bacterially expressed N protein and rabbit anti-PEDV serum was confirmed by immunofluorescence assays and Western blot. Both PEDV N protein and the polyclonal antibody generated in this study are valuable diagnostic reagents for PEDV surveillance.
Abstract
The enthalpies of solution of potassium chloride (KCl) in water and magnetically treated water (magnetized water) have been measured at 298.15 K using a LKB-8700 precision solution calorimeter. From the experimental results, it was observed that the effect of magnetic field on the enthalpy of solution is measurable. This is probably due to the distortion of the hydrogen bond of water resulting from magnetic treatment.
Abstract
A quantitative method including peak-fitting for determination of the content of short chain branching (SCB) in ethylene/α-olefin copolymers based on differential scanning calorimetry is described. After stepwise isothermal crystallization, the fractions with similar SCB and lamellar thickness are sorted into groups. The content of each group is determined using the peak-fitting area. The statistical terms, the arithmetic mean SCB content 
, the weighted mean SCB content 
and the branching broadness index 
are calculated. Through comparing with the SCB contents measured by 13CNMR analysis, the results show that this method can quantitatively characterize the content of SCB in ethylene/α-olefin copolymers with a high degree of accuracy.
A high-performance liquid chromatography—diode-array detection method was developed and validated to determine simultaneously eleven major alkaloids in Corydalis decumbens (Thunb.) Pers. The alkaloids detected were corlumidine, protopine, coptisine, tetrahydrojatrorrhizine, palmatine, berberine, sanguinarine, papaverine hydrochloride, tetrahydropalmatine, bicuculline, and corydaline. Chromatographic separation was achieved using a C-18 column with a mobile phase composed of A (0.2% acetic acid solution, adjusted with triethylamine to pH 5.0) and B (acetonitrile), with stepwise gradient elution. Ultraviolet diode-array detection was used; chromatograms were examined at the wavelength of 280 nm. The regression equations showed a good linear relationship between the peak area of each marker and concentration (r = 0.9994–0.9999). The recovery values ranged between 93.66% and 100.54%. The method was fully validated with respect to detection and quantification limits, precision, reproducibility, and accuracy. The described high-performance liquid chromatography (HPLC) method was successfully used for the differentiation and quantification of the eleven major alkaloids in C. decumbens (Thunb.) Pers. and can be considered an effective procedure for the analyses of this important class of natural compounds.
Abstract
Nitrogen-doped titanium dioxide (TiO2) nanotube arrays were synthesized by anodization in ethylene glycol electrolyte and annealing in ammonia at 500 °C. Detailed analysis showed that the nitrogen-doped titania nanotubes were pure anatase of ordered structure, with a crystallite size of 8.5 nm. The doping nitrogen atoms were induced on the interstitial sites and substitutional sites and the ratio of oxygen vacancies increased to 27.15 %, resulting in an add-on peak in the absorption spectrum and extended the absorption from 387 to 618 nm. The photocatalytic activity of the nitrogen-doped TiO2 nanotubes was evaluated by photocatalytic degradation of methyl blue under visible light irradiation. Significant improvement of photocatalytic activity under visible light irradiation was observed. We assumed the nitrogen doping induced the effect produced by nitrogen atoms, Ti3+ cations and oxygen vacancies and the size effect of the TiO2 crystallite should be responsible for the effective photocatalytic activity.
