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Abstract  

The comparison of an ambient temperature mercuric iodide spectrometer (HgI2) with a conventional cooled Si(Li) spectrometer is presented for the determination of niobium in Venezuelan laterites in the laboratory. The energy resolution of the HgI2 spectrometer was only about 590 eV (FWHM) at 5.9 keV compared to about 150 eV for the conventional Si(Li) spectrometer. The efficiency was about 5 times lower in the region of the NbK peak as compared to the Si(Li) detector. Even though its energy resolution and efficiency is much poorer than the conventional Si(Li), the results it produced for the determination of niobium were acceptable for use in the exploration and exploitation of a niobium-rich deposit such as Cerro Impacto, Estado Bolívar, Venezuela.

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Abstract  

Three different analytical methods for the determination of strontium and yttrium in Venezuelan latterites by radioisotope induced X-ray fluorescence are compared, also with results from conventional wavelength dispersive X-ray fluorescence. The samples analyzed were from Cerro Impacto, Venezuela. The photon-induced energy dispersive X-ray fluorescence system consisted of a109Cd (7 mCi) source for excitation of the characteristic K X-rays for strontium and yttrium. The detection system employed a high resolution Si(Li) detector and was completely controlled by a PDP-11/05 processor. Of the three analytical methods described, the internal standard-thin film technique was shown to be slightly superior to the conventional standard calibration curve method and the standard additon/dilution procedure. This can be explained by considering the effectiveness of the compensation of the sources of errors by these methods. It should also be noted that in the case of wavelength dispersive X-ray fluorescence, an about 5–10 times greater sample is needed, which is a limitation compared to energy dispersive X-ray fluorescence in some cases. Finally, typical relative standard deviations of the energy dispersive X-ray fluorescence methods were about 10–15% for the range of about 100–100 ppm of strontium and yttrium; these values are acceptable considering the large degree of heterogeneity in this type of geological material.

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Abstract  

A rapid radioisotope induced energy-dispersive X-ray fluorescence procedure for the simultaneous determinations of Cobalt, Nickel and Molybdenum in hydrodesulfurization catalysts is presented. A109Cd (7 mCi) source is used as the excitation system coupled to a high resolution Si(Li) detector. A PDP-11/05 processor is employed as a multichannel analyzer and also to automatically control the complete system by means of a prewritten computer program. The relative standard deviations for the three determinations (CoO, NiO and MoO3) are less than 5% for 300 seconds of fluorescent time for a typical sample. Finally a comparison of results by different methods is given to check the accuracy since no standard reference materials are available for catalytic material.

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Journal of Thermal Analysis and Calorimetry
Authors: C. Peña, K. de la Caba, A. Retegi, C. Ocando, J. Labidi, J. Echeverria, and I. Mondragon

Abstract  

Autocondensation reactions of mimosa and chestnut tannin extracts solutions have been analysed at several pH by differential scanning calorimetry (DSC). Alkaline pH promotes autocondensation reaction of these tannins. Curing reactions between these tannins and hexamine at acid and not strongly alkaline pH have been proved by DSC. Thermal analysis gives insights not only on reactions between tannin and hexamine, but also about water presence on solutions and degradation reactions of tannins. Products obtained from reactions between tannins and hexamine have been analysed by Fourier transform infrared spectroscopy (FTIR). The obtained chemical structures are influenced by both chemical structure of tannin and pH of solution. For mimosa tannin amine and ether groups are obtained while for hydrolysable chestnut tannin amide groups have been detected.

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Journal of Behavioral Addictions
Authors: Gemma Mestre-Bach, Roser Granero, Trevor Steward, Fernando Fernández-Aranda, Marta Baño, Neus Aymamí, Mónica Gómez-Peña, Zaida Agüera, Núria Mallorquí-Bagué, Laura Moragas, Amparo del Pino-Gutiérrez, Carles Soriano-Mas, Juan Francisco Navas, José C. Perales, José M. Menchón, and Susana Jiménez-Murcia

Background and aims

Gray’s Reinforcement Sensitivity Theory has been widely applied to different clinical populations, but few studies have reported empirical evidence based on this theory for treatment outcomes in patients with gambling disorder (GD) and compulsive buying (CB). The aims of this study were to explore the association between clinical variables and personality traits with reward and punishment sensitivity (RPS) levels in women (n = 88) who met diagnostic criteria for GD (n = 61) and CB (n = 27), and to determine the predictive capacity of RPS for primary short-term outcomes in a cognitive-behavioral therapy (CBT) intervention.

Methods

The CBT intervention consisted of 12 weekly sessions. Data on patients’ personality traits, RPS levels, psychopathology, sociodemographic factors, GD, and CB behavior were used in our analysis.

Results

High RPS levels were associated with higher psychopathology in both CB and GD, and were a risk factor for dropout in the CB group. In the GD group, higher reward sensitivity scores increased the risk of dropout.

Discussion and conclusions

Our findings suggest that both sensitivity to reward and sensitivity to punishment independently condition patients’ response to treatment for behavioral addictions. The authors uphold that CBT interventions for such addictions could potentially be enhanced by taking RPS into consideration.

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