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X-ray and gamma ray shielding behavior of concrete blocks
Hernandez-Murillo Christian Geovanni,Molina Contreras J. Rafael,Escalera-Velasco Luis Alberto,de Leon-Martínez Héctor Asael,Rodriguez-Rodriguez José Antonio,Vega-Carrillo Héctor Rene 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.8
The shielding characteristics of two concrete blocks, widely used in the building industry in Mexico have been determined. These characteristics include the mass interaction coefficients, the linear attenuation coefficients and the half-value layers. The energy-dispersed X-ray fluorescence shows that the percentage mass content of each atom in the sample, and the atomic volume of the constituent elements of a material, plays an important role in its shielding capabilities. The total linear attenuation coefficients and the half-value layers were analyzed for a set of photon energies related to X-rays for diagnosis and cancer treatment with linear accelerators. Our results show that the concrete blocks have similar photon attenuation coefficients than the Portland concrete and better features than gypsum
Victor E. Balderas Hernandez,Luz M. T. Paz Maldonado,Emilio Medina Rivero,Ana P. Barba de la Rosa,Leandro G. Ordonez Acevedo,Antonio De Leon Rodriguez 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.1
The production of human interferon gamma (hIFN-γ) using a synthetic gene in Escherichia coli BL21-SI was optimized by response surface methodology (RSM) and a Box-Behnken design. The process variables studied were temperature, biomass concentration at induction time and the NaCl concentration as inducer. According to the Box-Behnken design, a second order response function was developed. The optimal expression conditions were a temperature of 32.6℃, induction biomass of 0.31 g/L and 0.3 M NaCl in minimal medium. The model prediction for the maximum hIFN-γ production was 77.3 mg/L, which corresponded satisfactorily with the experimental data. The hIFN-γ concentration attained under optimized conditions was 13-times higher than that obtained using the non-optimized conditions. We conclude that RSM is an effective method for the optimization of recombinant protein expression using synthetic genes in E. coli.