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- Author or Editor: Dong Zhang x
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Abstract
The distribution coefficients,K d of 36 elements from Na to Bi on a silica were determined at pH 4, 7, 9 and in the absence and presence of fulvic acid (FA) using a multitracer technique. The multitracer solution was prepared by irradiation of Th(NO3)4 with 40Ar ion beam. The effects of pH and fulvic acid on the K d values of 36 elements were studied. It was found that the sequences of the K d values of alkali elements (Cs>Rb>K>Na) and of alkaline earth elements(Ba>Ca>Mg) in the absence of FA can be qualitatively explained in terms of chemical bond formation and hydration. Various effects of pH and the negative or positive effect of FA on the adsorption of 36 elements were observed and are probably related to the species of 36 elements in the aqueous solutions containing CO3 2–, OH–, Cl– and FA. For most of the elements studied here the K d values are increased with increasing pH and are decreased with adding FA.
Abstract
The stability constants for tracer concentrations of Co(II) complexes with both the red earth humic and fulvic acids were determined at pH 5.9 and ionic strength 0.010 mol/l by using theArdakani-Stevenson cation exchange equilibrium method and the radiotracer60Co. It was found that the 1:1 complexes of Co(II) with the red earth humic and fulvic acids were formed and that the average values of logβ (stability constant) of humic and fulvic acid complexes were 5.76±0.19 and 4.42±0.03, respectively.
Abstract
By substututing99Mo for the Mo in the reconstituted MoFe protein, the nuclear quadrupole interactions (NQI) of99Mo have been measured using the perturbed angular correlations (PAC). Two well-defined electric quadrupole interaction parameters have been observed. The configuration of the M-Center of the MoFe protein is identified by the quadrupole couplign constant 
Q1(412(9)MHz) and the asymmetry parameter 
1(0.49(5)). Other parameters, VQ2(1939(13)MHz) and
1(0.90(1)), may correspond to a deformation M—Center of MoFe protein.
Molecularly imprinted polymers (MIPs) were synthesized by imprinting a new template—S(-)-1,1′-binaphthalene-2,2′-diamine (S-DABN) and applied as chiral stationary phases for chiral separation of DABN racemates by high-performance liquid chromatography (HPLC). The influence of some key factors on the chiral recognition ability of MIPs, such as the type of functional monomers and porogen and the molar ratio of template to monomer, was systematically investigated. The chromatographic conditions, such as mobile phase composition, sample loading, and flow rate, were also measured. The chiral separation for DABN racemates under the optimum chromatographic conditions by using MIP chiral stationary phase (CSP) of P3, prepared with the S-DABN/MAA ratio = 1/4 and used acetonitrile (2 mL) and chloroform (4 mL) as porogen, showed the highest separation factor (2.14). Frontal analysis was used to evaluate affinity to the target molecule of MIPs. The binding sites (B t) of MIPs and dissociation constant (K d) were estimated as 4.56 μmol g−1 and 1.40 mmol L−1, respectively. In comparison with the previous studies, this approach had the advantages, such as the higher separation factor, easy preparation, and cost-effectiveness, it not only has the value for research but also has a potential in industrial application.
Abstract
The stability constants for tracer concentrations of Co(II) complexes with the red earth fulvic acid were determined at pH 3.8–6.8 and ionic strength 0.0010–1.0 mol/l by using the cation exchange equilibrium method and the radiotracer60Co. The effects of ionic strength and pH on the stability constants of 1∶1 Co(II) complexes were investigated, and it was found that the stability constants of complexes of humic substances do not vary with ionic strength and pH in a manner similar to that of simple complexes.
Trifolium repens Linn (white clover) is the main host of several economically important thrips species in Yunnan Province, in China. The diversity and relative abundance of thrips found on white clover were surveyed weekly via destructive collections from May 2009–May 2010 in Kunming. The 1786 thrips adults were collected and prepared on slides, eight thrips species were identified. The predominant species was western flower thrips (Frankliniella occidentalis), then followed by Megalurothrips distalis, Thrips flavus, Frankliniella intonsa, Thrips palmi, Thrips hawaiiensis, Thrips tabaci and Megalurothrips usitatus. The largest variation in abundance occurred in Mid-Autumn and late Winter, with Thrips flavus dominant at Mid-Autumn and Megalurothrips distalis dominant at late Winter. The correlativity results showed that the population of western flower thrips was significantly negatively correlated to the population of M. distalis (P<0.01), and no significant correlation was found between the population of western flower thrips and the other thrips (P>0.05) in Summer of 2009. In Spring of 2010, the population of western flower thrips was negatively correlated to the population of M. distalis (P<0.05), and it was no significant correlated to the population of the others thrips (P>0.05). However, no significant correlation was found between the population of western flower thrips and the others thrips (P>0.05) in both autumn and winter of 2009.
Background and aims
Although studies have suggested that individuals with Internet gaming disorder (IGD) may have impairments in cognitive functioning, the nature of the relationship is unclear given that the information is typically derived from cross-sectional studies.
Methods
Individuals with active IGD (n = 154) and those individuals no longer meeting criteria (n = 29) after 1 year were examined longitudinally using functional magnetic resonance imaging during performance of cue-craving tasks. Subjective responses and neural correlates were contrasted at study onset and at 1 year.
Results
Subjects’ craving responses to gaming cues decreased significantly at 1 year relative to study onset. Decreased brain responses in the anterior cingulate cortex (ACC) and lentiform nucleus were observed at 1 year relative to onset. Significant positive correlations were observed between changes in brain activities in the lentiform nucleus and changes in self-reported cravings. Dynamic causal modeling analysis showed increased ACC–lentiform connectivity at 1 year relative to study onset.
Conclusions
After recovery from IGD, individuals appear less sensitive to gaming cues. This recovery may involve increased ACC-related control over lentiform-related motivations in the control over cravings. The extent to which cortical control over subcortical motivations may be targeted in treatments for IGD should be examined further.
Abstract
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.
Abstract
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.
Abstract
In this work, a simple and rapid high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method was developed and validated to carry out the simultaneous measurement of busulfan (BU) and phenytoin (PHT) in the plasma of children. In this method, plasma sample could be prepared by one-step protein precipitation using 1 mL of methanol/water (1:1, v/v). After centrifugation (14,500 rpm, 5 min, 4 °C), 10 μL of the supernatant was injected into a Hypersil Gold C18 column (150 × 2.1 mm, 5 μm, Thermo Fisher Scientific) for separation by gradient elution. Quantification was carried out using multiple reactions monitoring (MRM) under positive scan mode. In the method verification, the calibration curves of BU and PHT showed satisfactory linearity (r > 0.99) at the concentration ranging from 0.02 to 20 μg mL−1. The accuracy and precision were tested at four concentration levels (including the LLOQ level) with the relative error (RE) ranging from −0.80% to 11.45% and coefficient of variation (CV) between 0.93% and 7.74%. There was no pronounced matrix effect to interfere with the quantitative analysis. Compared to determine BU and PHT using two individual methods, less pre-treatment process, labor and blood sample volume are required in this proposed method. Finally, this method was successfully applied to the therapeutic drug monitoring of BU and PHT for children underwent hematological stem cell transplantation.
