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- Author or Editor: C. Wai x
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Abstract
Uranium in aqueous solution can be extracted by sym-dibenzo-16-crown-5-oxy-acetic acid and its modified analogue 2-/sym-dibenzo-16-crown-5-oxy/-hexanoic acid into chloroform in the pH range 5.5–6.0. The extraction method combined with neutron activation analysis provides a sensitive method for the determination of uranium in natural waters.
Abstract
Palladium/II/ in aqueous solution can be selectively extracted by bismuth diethyl-dithiocarbamate into chloroform at pH around 3.5. This preconcentration procedure combined with neutron activation analysis provides an extremely sensitive method for measuring low levels of Pd in natural samples. Applications of this method to Pd determination in natural water and in coal fly ash are described.
Abstract
At pH 2, Au, Pd, Pt, U and W form stable pyrrolidine-carbodithioate (PCDT) complexes which can be quantitatively retained by C18-bonded silica gel. Simultaneous determination of the adsorbed metal complexes can be achieved by instrumental neutron activation analysis (INAA). This method allows the determination of Au, Pd, U, and W in natural waters at ng/l levels. For Pt and W, the adsopriton method has an advantage over the solvent extraction technique which generally results in a partial recovery of the PCDT complexes.
Abstract
The effect of solvents on the extraction of lanthanoids with 18-crown-6 and trichloroacetic acid was investigated for the solvents, 1,1,-dichloroethane, 1,2-dichloroethane, 1,1, 2,2-tetrachloroethane, chloroform, di-2-chloroethyl ether, and methylene chloride. Distribution coefficients (25 °C) normalized to the water solubility (wt./vol.) in the solvents correlated to the polarizability index (
*) for La3+, Ce3+, Pr3+, and Nd3+ with r values=0.93,0.93,0.95, and 0.98, respectively. The distribution coefficients for Nd3+ also correlated with the Hildebrand solubility parameter (
) (r=0.98). These correlations agree with the literature that for large ions, the extraction thermodynamic properties correlate with the polarizability index and Hildebrand solubility parameter.
Abstract
A three-step method has been developed for extracting trace amounts of selenium from biological samples for neutron activation analysis /NAA/. After acid digestion, the sample is first extracted with lead diethyldithiocarbamate at pH 4 to remove a number of interfering elements. Next, selenium is extracted with sodium diethyldithiocarbamate into chloroform at pH 1.5. Finally, selenium is back-extracted with concentrated nitric acid for NAA. Analysis of selenium extracted from four standard reference materials resulted in excellent agreement with the certified values of selenium concentration. A detection limit of 0.05 
g has been achieved.
Abstract
This paper introduces a new type of extractant, sym-dibenzo-16-crown-5-oxyhydroxamic acid (HL). The extraction of UO
2
2+
, Na+, K+, Sr2+, Ba2+ and Br– were studied with HL in chloroform. The results obtained show that UO
2
2+
can be quantitatively extracted at pH above 5, whereas the extractions of K+, Na+, Ba2+ and Br– are negligible in the pH range of 2–7. The dependence of the distribution ratio of U(VI) on both the concentration of the HL and pH are linear, and they have the same slope of 2. This suggests that U(VI) appears to form a 1
2 complex with ligand.Uranium (VI) can be selectively separated and concentrated from interfering elements such Na, K, Sr and Br by solvent extraction with HL under specific conditions. The recovery of uranium is nearly 100% and the radionuclear purity of uranium is greater than 99.99%. Therefore, it has greatly improved the sensitivity and accuracy for the detection of trace uranium from seawater by neutron activation analysis.
Abstract
A lanthanum fluoride precipitation method for the separation of18F produced from the18O(p,n)18F reaction in alkali halide salts is described. This radiochemical separation method minimizes interferences from other positron emitters produced by proton bombardment and makes the accurate determination of ppm-level18O in complex alkali halide systems feasible. The interference from the19F(p,d)18F reaction is eliminated by keeping the proton energy less than 8.2 MeV. Applications of this technique to studies of dissolved oxide species in molten alkali halide salts are discussed.
Background and aims
Internet gaming disorder (IGD) imposes a potential public health threat worldwide. Gaming motives are potentially salient factors of IGD, but research on Chinese gaming motives is scarce. This study empirically evaluated the psychometric properties of the Chinese version of the Motives for Online Gaming Questionnaire (C-MOGQ), the first inventory that measures seven different gaming motives applicable to all type of online games. We also investigated the associations between various gaming motives and IGD symptoms among Chinese gamers.
Methods
Three hundred and eighty-three Chinese adult online gamers (Mean age = 23.7 years) voluntarily completed our online, anonymous survey in December 2015.
Results
The confirmatory factor analysis results supported a bi-factor model with a general factor subsuming all C-MOGQ items (General Motivation) and seven uncorrelated domain-specific factors (Escape, Coping, Fantasy, Skill Development, Recreation, Competition, and Social). High internal consistencies of the overall scale and subscales were observed. The criterion-related validity of this Chinese version was also supported by the positive correlations of C-MOGQ scale scores with psychological need satisfaction and time spent gaming. Furthermore, we found that high General Motivation (coupled with high Escape motive and low Skill Development motive) was associated with more IGD symptoms reported by our Chinese participants.
Discussion and conclusions
Our findings demonstrated the utility of C-MOGQ in measuring gaming motives of Chinese online gamers, and we recommend the consideration of both its total score and subscale scores in future studies.
