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[en] Over the past few years, various materials used in masonry, such as lead, concrete, ceramic blocks and brick, have been studied for use as shielding against ionizing radiation from different energies in radioactive facilities. In the area of diagnostic radiology, lead and barite are the most used materials as shielding, but for bundles of low energy X radiation, as in mammography and dentistry, plaster material can be used, as affirmed by the National Council on Radiological Protection and Measures through its report number 147 (NCRP Report Nº 147). This work developed plaster phantoms as well as gypsum & barite mixing with plate formats with a 10 x 10 centimeter area, aiming to characterize physico-chemically and verify the feasibility of using these materials as shielding against low-energy X-ray radiation, using mammographic X-ray bundles in metrology laboratories. From the irradiation, it was possible to obtain the transmissions curves, to discover the Half Value Layers (HVL) and the Tenth Value Layers (TVL), as well as to acquire the different spectra for each material. The gypsum & barite mixing material had a better shielding response compared to pure gypsum material, however both can be considered as good attenuators against low energy X radiation. (author)
[en] The advanced condition of deterioration of the column’s bases of the courtyard of the Bishop’s Palace of Tarazona (Spain) built in the middle of 16th century required its restoration with Aragonese alabaster. Thus, adapted ageing tests were developed to simulate the environmental conditions in which the stones were and will be exposed. These tests were thermal fatigue by temperature variations, acid rain and water stagnation by immersion tests and a combination of both agents of decay. The results indicated that alabaster did not experimented deformation after thermal fatigue but a progressive dehydration to bassanite. This process entailed an increase of porosity and consequently a loss of structural properties. The dissolution was measured as a lineal weight and volume loss while porosity and capillary uptake remained stable. The conclusions of this study establish the importance of restoration protocols to maintain the alabaster integrity when used and exposed to rainwater and insolation.
[es]Las basas deterioradas de las columnas del patio del Palacio Episcopal de Tarazona (España), construido a mediados del siglo XVI, fueron restauradas con alabastro aragonés. Por lo tanto, se han desarrollado pruebas de envejecimiento adaptadas para simular las condiciones ambientales en las que las piedras estaban y estarán expuestas, fatiga térmica por variaciones de temperatura, lluvia ácida, inmersión en agua y una combinación de agentes de deterioro. Los resultados indican que el alabastro no experimentó deformación después de la fatiga térmica, sino una progresiva deshidratación a bassanita, lo cual implica un aumento de porosidad y una pérdida de propiedades estructurales. La disolución se midió como una pérdida lineal de peso y volumen, mientras que la porosidad y el ascenso capilar se mantuvieron estables. Se desprende la importancia de adoptar protocolos de restauración para mantener la integridad del alabastro cuando se expone al agua de lluvia e insolación.
[en] Uranium(IV) oxide clusters, colloids, and materials are designed and studied for 1) nuclear materials applications, 2) understanding the environmental fate and transport of actinides, and 3) exploring the complex bonding behavior of open-shell f-elements. U-oxyhydroxsulfate clusters are particularly relevant in industrial processes and in nature. Recent studies have shown that counter-cations to these polynuclear anions differentiate rich structural topologies in the solid-state. Herein, we present nine different structures with wheel-shaped [U(OH)(O)(SO)] (U) linked into one- and two-dimensional frameworks with sulfate, divalent transition metals (Cr, Fe, Co, Ni) and U. Small-angle X-ray scattering of these phases dissolved in butylamine reveals differing supramolecular assembly of U clusters, controlled primarily by sulfates. However, observed trends in transition metal linking guide future design of U materials with different topologies. Finally, U linking via U-O-U-O-U bridges presents a rare example of mixed-oxidation-state uranium oxides without disorder. (© 2020 Wiley‐VCH GmbH)
[en] At present, the most common substance used in radiation protection is lead. However, lead is a heavy metal that is harmful to the human body and causes environmental pollution. BaSO4 is an excellent material for X-Ray shielding because it has good X-Ray shielding ability and it is cheap. In this study, we fabricated Gypsum-BaSO4 (G-B) shields with gypsum and BaSO4 and Cement-BaSO4 (C-B) shields with cement and BaSO4 and conduct two tests (X-Ray shielding test, Strength test) to evaluate the performance of the shields. First of all, G-B, C-B Shields at 15 mm thickness were fabricated to evaluate X-Ray shielding performance, including 1.0, 1.5 mm thickness lead and IKEN Board. To achieve X-Ray shielding capability of 1.5 mm lead at 100 kV X-Ray tube voltage, BaSO4 content 66% G-B shield and 68% C-B shield were required. Secondly, flexural strength test was conducted for G-B and C-B shields. Test results show that at the same BaSO4 content, C-B shields were stronger than G-B shields. BaSO4 content 68% C-B shield was 3.5 times stronger than 66% G-B shield
[en] Herein, we report the discovery of a toroidal inorganic cluster of zirconium(IV) oxysulfate of unprecedented size with the formula Zr(SO)(O/OH)⋅x(HO) (Zr), which displays different packing of ring units and thus several polymorphic crystal structures. The ring measures over 3 nm across, has an inner cavity of 1 nm and displays a pseudo-10-fold rotational symmetry of Zr octahedra bridged by an additional Zr in the outer rim of the ring. Depending on the co-crystallizing species, the rings form various crystalline phases in which the torus units are connected in extended chain and network structures. One phase, in which the ring units are arranged in layers and form one-dimensional channels, displays high permanent porosity (BET surface area: 241 m g), and thus demonstrates a functional property for potential use in, for example, adsorption or heterogeneous catalysis. (© 2020 Wiley‐VCH GmbH)
[en] Objective: To compare the efficacy of oral zinc sulphate with cryotherapy in the treatment of viral warts. Study Design: Quasi-experimental study. Place and Duration of Study: Department of Dermatology, Combined Military Hospital Malir, from Nov 2018 to Apr 2019. Methodology: A total of 210 patients (105 in each group) were included in this study. We randomized the patients into two equal groups, A and B by lottery method. Patients of both genders with cutaneous warts between the ages of 18 to 65 years. Patients with genital warts, cardiac, hepatic and renal disease, and hypercholesterolemia were excluded. Patients in group A were given oral zinc sulphate 10mg/kg/day for 8 weeks. Patients in group B were treated with cryotherapy after every 2 weeks for 8 weeks. Results: Mean age of the patients was 39.30 ± 11.35 years and 38.92 ± 10.32 years in group A and B, respectively. In group A, 63 patients (60%) and in group B, 62 patients (59%) were males while 42 patients (40%) of group A and 43 patients (41%) of group B were females. Oral zinc sulphate was found to be effective in 67 patients (63.8%) and cryotherapy in 39 patients (37.2%). Statistically significant difference was observed between the two groups (p<0.001). Conclusion: The results suggested that oral zinc sulphate is more effective than cryotherapy in the treatment of viral warts. (author)
[en] This paper presents the study of four gypsum mixtures, focusing on the role of both inorganic and organic additives and on the micro-structural features and mechanical properties. Additives have been chosen among those most reported in historical recipes, for example magnesia, lime putty, rabbit glue. The selected mixes refer to gypsum-based materials used in artworks manufacture, such as plasters, mouldings, stuccoworks, pastiglia. Blank reference materials were prepared on purpose according to the specific recipe, in order to verify the final composition and to highlight the hardening mechanisms and the formation of setting compounds. The chemical composition was related to workability properties and final mechanical resistance and the action of additives as retardants was studied with interesting results. For instance, MgO imparts good properties to the mechanical features, especially with regard to the compressive strength characteristics.
[es]En este artículo se han analizado cuatro mezclas basadas en yeso y se ha estudiado la influencia de los aditivos utilizados para su preparación, tanto orgánicos como inorgánicos, sobre las propiedades mecánicas y microestucturales de los materiales resultantes. Los aditivos utilizados se seleccionaron en base a aquellos que han sido principalmente publicados en recetas históricas, tales como magnesia, cal o cola de conejo. Por su parte, las mezclas basadas en yeso se eligieron en base aquellas principalmente utilizadas en obras de arte, incluyendo escayolas, molduras, estucados o pastiglia. También se prepararon materiales de referencia (control), de acuerdo a una mezcla específica, para verificar la composición química de las diferentes mezclas preparadas y comparar sus mecanismos de endurecimiento y formación. La composición química de los materiales preparados se ha correlacionado con su trabajabilidad y resistencia mecánica. Además, se estudió la acción retardante de los aditivos utilizados con interesantes resultados. Por ejemplo, el MgO confiere buenas propiedades mecánicas al material, especialmente en lo que se refiere a la resistencia a la compresión
[en] High-temperature corrosion of aluminized-American Iron and Steel Institute (AISI) 1020 steel with sodium chloride (NaCl) and sodium sulphate (Na2SO4) deposits was studied using isothermal oxidisation in a dry air environment at 700℃ for 49 h. NaCl and Na2SO4 deposits on the aluminide layer interfered with protective alumina/aluminium oxide(Al2O3) scale formation on the steel substrate. Chlorine and sulphur gases (Cl2g and Sg, respectively) released into the atmosphere corroded the protective Al2O3 layer. Corrosion of the Al2O3 layer was also due to local formation of iron oxide (Fe2O3). Fe2O3 growth is attributed to ferric chloride (FeCl3) vaporization. Sg diffusion into the Al2O3 scale via Al3+ vacancy defects led to the formation of aluminium sulphide on the aluminide layer surface. Cl and S consequently induced hot corrosion of the aluminized steel, thereby increasing cyclic oxychloridation and sulphidation rates at high temperatures. (author)
[en] The objective of this paper is to estimate the combined uncertainty in the measurement of dose equivalent at laboratory level using CaSO4:Dy-based thermoluminescent dosemeter badge system by including variations in the components of the system. The variability of performance of the system is analysed using random effects one way analysis of variance model. The model enables estimation of the overall variance of the performance of the sampled population. The population in the study comprises all possible indicated dose equivalents on irradiation of dosemeters to a specific dose equivalent and radiation quality. Coefficient of variation and combined uncertainty at 95% level of confidence in the measurement of Hp(10) due to S-Cs radiation quality are found to be 6.6 and 14.3%, respectively, at the dose level of 5.31 mSv. The above parameters in the measurement of in-use quantity, i.e. whole body dose or photon dose equivalent are found to be 7.4 and 16.4%, respectively. The performance of the monitoring system on relative response has been observed to be satisfactory. Various factors affecting the variability of performance of the system are identified for further improvement in coefficient of variation. (authors)
[en] This exploratory research focused on the adsorption of Sr(II) on the sodium dodecyl sulfate modified palygorskite (SDS/Pal). The ion exchange reactions existed, and the elements Mg, Al, Si and Fe on the Pal were exchanged by element Sr(II). The adsorption process could be well described by the pseudo-second-order kinetics and Langmuir model. The adsorption capacity increased from 24.91 to 61.87 mmol g-1 with the increase of initial concentration from 10.0 to 100.0 mg L-1. SDS/Pal is potential for the adsorption of Sr(II) from aqueous solution. (author)