Uranium-238 (U) and potassium-40 (K) are important naturally occurring radionuclides. Gamma spectroscopy is a direct, non-destructive method used to determine radionuclide concentrations, but it suffers from the interference of gamma lines. K gamma spectroscopy is affected by background interference, which leads to a reduction in the minimum detectable activity. The energy dispersive X-ray analytical technique is quick, with fewer interference problems or background effects. However, it is an indirect method for calculating and deducing the concentrations of isotopes. The aim of the present study was to compare and evaluate both techniques so that they can be utilized efficiently. The results of U and K were measured by well-calibrated gamma spectroscopy and energy dispersive X-ray techniques. the results indicated that Halayeb White granite is the most environmentally safe compared to the other two types because it contains a very low concentration of uranium 238 and potassium 40.
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http://dx.doi.org/10.3390/ma15155130 | DOI Listing |
Front Child Adolesc Psychiatry
November 2024
Faculty of Human Sciences, Sophia University, Chiyoda-ku, Tokyo, Japan.
Introduction: The (EMB) theory, a major causal hypothesis of autism (ASD: autism spectrum disorder), attributes excess androgens during early development as one of the causes. While studies have generally followed the EMB theory in females at birth, the co-occurrence of ASD in males at birth has been observed in conditions that are assumed to be associated with reduced androgen action during early development, including Klinefelter syndrome (KS) and sexual minorities. ASD is also associated with atypical sensory sensitivity, synesthesia, and savant syndrome.
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Mineralogical Society of Antwerp, Boterlaarbaan 225, 2100 Deurne, Belgium.
ConspectusWhile photochromic natural sodalites, an aluminosilicate mineral, were originally considered as curiosities, articles published in the past ten years have radically changed this perspective. It has been proven that their artificial synthesis was easy and allowed compositional tuning. Combined with simulations, it has been shown that a wide range of photochromic properties were achievable for synthetic sodalites (color, activation energy, reversibility, etc.
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January 2025
Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577, Japan.
Sodium borohydride dihydrate (NaBH·2HO) forms through dihydrogen bonding between the hydridic hydrogen of the BH ion and the protonic hydrogen of the water molecule. High-pressure structural changes in NaBH·2HO, observed up to 11 GPa through X-ray diffraction and Raman scattering spectroscopy, were analyzed to assess the influence of dihydrogen bonds on its crystal structure. At approximately 4.
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January 2025
Institute of Organic Chemistry, University of Leipzig, 04103 Leipzig, Germany.
The enantioselective synthesis of 1,4-dicarbonyl compounds continues to pose a significant challenge in organic synthesis, and a catalytic process which generates two adjacent stereogenic centers with full stereochemical control is lacking until now. The 1,4-relationship of the functional groups requires an Umpolung strategy as one of the α-carbonyl positions has to be inverted into an electrophilic center to react with a normal enolate. We report herein the highly enantio- and diastereoselective addition of silyl ketene acetals toward electrophilic 1-azaallyl cations to furnish chiral 4-hydrazonoesters, which are masked 1,4-dicarbonyl compounds.
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January 2025
Grupo de Investigación en Energías Renovables y Meteorología-GIERMET, Universidad Tecnológica del Chocó, Cra 22 No 18b -10, Quibdó, Colombia.
The corrosion rates of carbon steel and galvanized steel according to the ISO 9223 standard, the effect of pollutant contamination and atmospheric aggressiveness under high rainfall conditions in the Chocó department were studied. Carbon and galvanized steel samples, chloride, and sulfur collectors were exposed in three atmospheric stations in three strategic positions covering the Colombian Pacific: Quibdó, Andagoya and Bahía Solano, for different exposure periods (up to 18 months). The structural-micro characterization of corrosion products was evaluated via X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy SEM-EDS.
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