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  • Author or Editor: M. Chen x
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Both melatonin and leptin show a circadian variation in circulating levels and participate in energy metabolism. An interrelationship between these two hormones has thus been proposed. In addition, melatonin has been shown to be capable of influencing circulating leptin concentration. However, whether melatonin will increase or decrease leptin production is still uncertain. This study was undertaken to examine the effect of melatonin on leptin production using male C57BL/6 adult mice treated with or without daily melatonin supplements (10 μg/mL) in drinking water for 1 month. In addition, in vitro experiments using adipose tissue fragments derived from epididymal fat pads of adult mice incubated with or without melatonin (1 nM) administration were also conducted. The results showed that melatonin-supplemented mice had significantly higher plasma leptin levels than control mice. However, melatonin incubation did not cause any marked changes in the amount of leptin secreted from adipose tissue fragments. Our findings from this study indicate that melatonin does not affect leptin secretion via mouse adipose tissue. Nevertheless, melatonin could still influence leptinemia indirectly via regulatory effects in intact animals.

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Blue sticky traps on 3.0 m high poles were used to determine the characteristics of Thrips tabaci and Frankliniella occidentalis migratory flight in Israel from 2003 to 2007. In an open area, both thrips species were caught from March to November. The dominant species was T. tabaci except during the spring. About 70% of the thrips were caught below 1.0 m above ground. Trapping height appears to reflect thrips’ concentration gradient in the air because it was not affected by setting up the poles over a sticky surface. From April to September the westerly sea breezes usually exceed 10 km/h from late morning to twilight time. As a result, about 85% and 10% of the thrips were caught in the morning and at dusk, respectively. When we used similar traps mounted on wind vanes, at 1.0 m above ground 70% of the thrips were caught on the leeward side. Thus, it appears that thrips fly mainly upwind during their migration. Indeed, while most prevailing winds are from the west, most thrips were caught on the eastern side of the poles (40–50%) and the fewest on the western side (10–20%). This information may be used to focus monitoring and control of these thrips in time and space.

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Abstract  

The present study explores the feasibility of the determination of phosphorus at the extreme trace levels in high-purity silicon by radioreagent method. After silicon dissolution with hydrofluoric and nitric acids and matrix volatilization, 12-molybdophosphoric acid (12-MPA) is formed by the addition of the radioreagent,99MoO 4 2– , in nitric acid medium and then extracted into isobutyl acetate. By plotting the phosphorus content against the radioactivity of99Mo in the organic phase, a linear relationship persisting down to 5 ng is obtained. Special effort has been made to the elimination of the unreacted99MoO 4 2– reagent and the optimal control of phosphorus blank introduced through the multistage analytical procedure in order to ensure reliable determination of phosphorus at the ppb level.

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A non-destructive method for the analysis of yttrium, aluminum and oxygen in Yttrium Aluminum Garnet /YAG/ by 14 MeV neutron activation analysis has been developed and evaluated. The fast neutron induces primarily /n, 2n/, /n, p/ or /n, / reactions with yttrium, aluminum, and oxygen to produce isotopes with measurable characteristic gamma-ray spectra. Concentrations of Y, Al and O were determined on the basis of calibrated nuclear decay emission spectra recorded on selected standards. After each analysis the crystal was returned to the furnace for further adjustments of the growth parameters, and any resultant elemental variations were observed in the next analysis. The accuracy of this method was determined by repeated analyses with various YAG crystals from a series of separate furnace runs.

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Abstract  

A fully automated neutron activation analysis (NAA) facility has been constructed at the Whiteshell Nuclear Research Establishment. This high-capacity facility has been designed for use with a wide variety of neutron sources, including Canada's SLOWPOKE II and MAPLE research reactors. Its pneumatic transfer system is driven by a Square-D Model 500 programmable controller, linked in turn to a Nuclear Data ND6700 computer/spectrometer. Custom software for data entry and system control has been combined with Nuclear Data software for gamma-spectrum acquisition and processing to create a flexible, easy-to-use facility for NAA. Its design and performance are discussed.

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A series of Zn–Al hydrotalcites with Zn/Al molar ratios of 1, 2, 3 and 6 were prepared by co-precipitation method. TG-DTG results showed that the hydrotalcites decompose in two stages, corresponding to the two endothermic peaks around 180 and 220°C. After calcination at 400°C, the samples were converted into Zn–Al mixed oxides with the only XRD pattern of ZnO, except for the sample with the ratio of 6. The Zn–Al mixed oxides possess similar surface acidity revealed by microcalorimetric adsorption of NH3. The basicity of the samples increases with the order: ZnO>6Zn/Al>1Zn/Al>Al2O3.

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A method combining prior collection of gaseous products with subsequent neutron activation analysis has been developed for simultaneous determination of traces of arsenic, mercury, antimony and selenium in biological materials. The generation of hydrides of arsenic, antimony and selenium and cold vapor of mercury in the vapor generaion and collection system was investigated by the use of radiotracers of the respective elements. The result indicates that selenium and mercury can be completely evaporated from the digested sample solution in 5M HCl with the addition of 5% sodium tetrahydroborate solution, while additional reduction proces by potassium iodide and ascorbic acid is needed for complete evaporation of arsenic and antimony. The gaseous products were collected in a quartz tube for neutron irradiation. The detection limits of these elements were fount to be in the range of 10–7 to 10–8 g under the present experimental conditions. The reliability was checked with NBS standard reference materials.

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Building Information Modelling (BIM) has become an emerging digital technology in the architecture, engineering and construction (AEC) industry. There is a growing demand on applying BIM for sustainable design including the building energy simulation (BES). Lack of sufficient interoperability has caused barriers to utilize the information from BIM for BES. In this study, the interoperability between BIM and four different BES tools (i.e., Ecotect, EQUEST, Design Builder and IES-VE) was explored by using a case study of a residential building in the design stage. The misrepresented information from BIM to multiple BES tools were identified based on six different categories of building information parameters. The research proposed an approach of creating gbXML file with an improved integrity of information in BIM. Overall, this study would lead to further work in developing platforms for improving the information transformation from BIM to BES.

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Zinc (Zn) has the potential of regulating the action of thiazolidinedione (TZD), an anti-diabetic drug. Since some diabetic patients cannot achieve optimal glycemic control when receiving TZD, we investigated if Zn deficiency affects TZD’s efficacy in glucose metabolism. Diabetic mice were fed diets containing 3 or 30 mg/kg Zn for 6 weeks. Thereafter, all mice were oral gavaged with 2,4-thiazolidinedione. Our results showed that blood glucose values at fasting and during the glucose tolerance test were significantly higher in low-Zn mice than those of adequate-Zn mice. Thus, low Zn intake may attenuate TZD’s efficacy on reducing diabetic hyperglycemia.

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Abstract  

The concentrations of ten trace and dopant elements in GaAs semiconductor were determined by reactor neutron activation analysis after removal of As by evaporation of AsCl3. The retentions of the elements of interest were measured using radiotracers. The concentrations of doping elements (Te, Cr and Zn) in commercial GaAs samples were compared to the limit of detection of these elements to analyze the possibility to use NAA for concentration depth profiling measurements. The NAA results were compared with those of electrical measurements and SIMS and the discrepancies found are discussed.

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