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Abstract  

In order to measure 182Hf by accelerator mass spectrometry (AMS), a chemical procedure for separation of hafnium from tungsten has been developed by extraction chromatography. The extraction chromatographic behavior of hafnium and tungsten has been studied using tri-n-octylamine (TOA) as the stationary phase, HCl–H2O2 mixture and NH3·H2O as the mobile phase. The effects of H2O2 concentration, column loading and column dimensions are investigated. Hf and W with microgram amounts are successfully separated on a chromatographic column (Ø5 × 196 mm), on which Hf is hardly retained after completely eluted with 6 M HCl–1% H2O2 and W strongly adsorbed is then eluted with 3 M NH3·H2O. The decontamination factor for tungsten is 3.0 × 105 and the recovery of hafnium is better than 99% using a single column separation.

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Abstract  

Humic substances have attracted great interest in the investigation of metal ion behavior in the environment because of their special properties. Sorption and complexation of Pb2+ on MX-80 bentonite, LA bentonite, alumina and silica as a function of pH were studied in the presence and absence of fulvic acid (FA). The experiments were carried out in 0.01M and 0.001M NaNO3 solutions under ambient conditions. The results indicate that sorption of Pb2+ on the solid samples is strongly dependent on pH and FA. The sorption of Pb2+ is not influenced drastically by ionic strength. The nature of minerals/oxides, nature of humic substances and the composition of the solution are important factors in the behavior of metal ions in the environment. The results also indicate that FA has a positive effect on Pb2+ sorption at low and a negative effect at high pH values, and the results are discussed in the comparative complexation between FA-Pb2+ and Pb2+-minerals.

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Abstract  

Sorption of Th(IV) on Na-rectorite as a function of pH, ionic strength, soil humic acid (HA) and fulvic acid (FA) are studied under ambient conditions by using a batch technique. The results indicate that the sorption of Th(IV) on Na-rectorite is not only dependent on medium pH values, but also dependent on medium ionic strength and humic substances. Surface complexation and cation competition exchange account for Th(IV) sorption on Na-rectorite. The sorption of Th(IV) on Na-rectorite decreases with the increase on the concentration of NaNO3, Mg(NO3)2 and Ca(NO3)2, and increases with the increasing amount of HA/FA in the suspension/adsorbed on rectorite. Soil HA/FA enhances the sorption of Th(IV) on rectorite at medium pH<4 drastically, but the presence of FA reduces the sorption of Th(IV) at medium pH>6, and HA has no effect on Th(IV) sorption at medium pH>6. An interpretation for the results is attempted, considering the occurrence of different sorption mechanisms.

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Abstract

Background

Researchers are only just beginning to understand the neurocognitive drivers of addiction-like eating behaviours, a highly distressing and relatively common condition. Two constructs have been consistently linked to addiction-like eating: distress-driven impulsivity and cognitive inflexibility. Despite a large body of addiction research showing that impulsivity-related traits can interact with other risk markers to result in an especially heightened risk for addictive behaviours, no study to date has examined how distress-driven impulsivity interacts with cognitive inflexibility in relation to addiction-like eating behaviours. The current study examines the interactive contribution of distress-driven impulsivity and cognitive inflexibility to addiction-like eating behaviours.

Method

One hundred and thirty-one participants [mean age 21 years (SD = 2.3), 61.8% female] completed the modified Yale Food Addiction Scale, the S-UPPS-P impulsivity scale, and a cognitive flexibility task. A bootstrap method was used to examine the associations between distress-driven impulsivity, cognitive inflexibility, and their interaction with addiction-like eating behaviours.

Results

There was a significant interaction effect between distress-driven impulsivity and cognitive flexibility (P = 0.03). The follow-up test revealed that higher distress-driven impulsivity was associated with more addiction-like eating behaviours among participants classified as cognitively inflexible only.

Conclusion

The current findings shed light on the mechanisms underlying addiction-like eating behaviours, including how traits and cognition might interact to drive them. The findings also suggest that interventions that directly address distress-driven impulsivity and cognitive inflexibility might be effective in reducing risk for addiction-like eating and related disorders.

Open access
Journal of Radioanalytical and Nuclear Chemistry
Authors: Chang-Kyu Kim, A. Takaku, M. Yamamoto, H. Kawamura, K. Shiraishi, Y. Igarashi, S. Igarashi, H. Takayama, and N. Ikeda

Abstract  

A new analytical technique using ICP-MS was applied to the determination of237Np in some environmental samples. The accuracy and precision of the new method were assessed by comparison with those of conventional NAA and -spectrometric method as well as by analysis of the intercomparison sample of Ravenglass NRPB silt. The results obtained by ICP-MS were in good agreement with those by NAA or -spectrometry at a relative deviation of 2–9%. The detection limit is 0.02 mBq/ml (26 mBq=1 ng).

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An accurate and rapid liquid chromatography–electrospray ionizaion– tandem mass spectrometry (LC—ESI—MS/MS) analytical method was developed and validated for the simultaneous determination of antcins A, B, C, H, and K, dehydroeburicoic acid, and 4,7-dimethoxy-5-methyl-1,3-benzodioxole in the extract and capsule of Antrodia cinnamomea (AC) fruiting body. These seven signature compounds were ionized using an electrospray ion source and analyzed by a triple-quadrupole mass analyzer under a multiple reaction monitoring (MRM) mode. The MRM transitions of m/z 453/409 (antcin A), m/z 467/408 (antcin B), m/z 469/425 (antcin C), m/z 485/413 (antcin H), m/z 487/407 (antcin K), m/z 467/337 (dehydroeburicoic acid), and m/z 197/139 (4,7-dimethoxy-5-methyl-1,3-benzodioxole) were used to quantify these seven components, respectively. Their calibration curves presented good linear regressions (R 2 > 0.997) within the tested concentration range. The intra- and inter-day precisions were less than 1.97% and 2.53%, respectively. The overall recovery was in the range of 87.55%–95.41%. This validated high-performance liquid chromatography (HPLC)—MS/MS method offers promising applications for the accurate and rapid quantification of signature compounds in the fruiting body and its commercial products.

Open access