Gamma-rays shielding properties of xPbO:(100 − x)B2O3 glasses system at 662 keV

The mass attenuation coefficients, total interaction cross-sections and effective atomic numbers of xPbO:(100 − x)B₂O₃ (where 30  x  70% weight) glass system have been investigated on the basis of the mixture rule. The results are good agreement with the theoretical values, calculated by WinXCom. Mass attenuation coefficients were increased with increase PbO content, due to increase effective atomic number of glass samples, which increase probability of photoelectric absorption in glass. However, Compton scattering gives dominant contribution to the total mass attenuation coefficients for studied glass samples. Their shielding properties of glass samples are also better than ordinary shielding concretes and commercial window glass which can be used with advantage as transparent in visible region. These results are indicating the potential of glasses in radiation shielding materials.     

Mass transfer parameter estimation using optimization technique: Case study in CO2 absorption with chemical reaction

This paper proposes a new approach of applying an optimization technique to simultaneously determine a physical liquid—film mass transfer coefficient (K^o_L) and effective interfacial area (a_v) from a pilot plant data. The mass transfer mechanism of the CO₂-NaOH system was modeled using the two-film theory to represent the behaviors of packed absorbers. The model presents an overall absorption rate (R_v) as a function of K^o_L and a_v. The optimization algorithm used in this study follows a modified Levenberg-Marquardt method with a trust region approach. The R_v predictions from the model are in good agreement with the experimental data, with an average error of 6.5%.     

Anti-listeria activity of poly(lactic acid)/sawdust particle biocomposite film impregnated with pediocin PA-1/AcH and its use in raw sliced pork

A novel poly(lactic acid) (PLA)/sawdust particle (SP) biocomposite film with anti-listeria activity was developed by incorporation of pediocin PA-1/AcH (Ped) using diffusion coating method. Sawdust particle played an important role in embedding pediocin into the hydrophobic PLA film. The anti-listeria activity of the PLA/SP biocomposite film incorporated with Ped (PLA/SP + Ped) was detected, while no activity against the tested pathogen was observed for the control PLA films (without SP and/or Ped). Dry-heat treatment of film before coating with Ped resulted in the highest Ped adsorption (11.63 ± 3.07 μg protein/cm²) and the highest anti-listeria activity. A model study of PLA/SP + Ped as a food-contact antimicrobial packaging on raw sliced pork suggests a potential inhibition of Listeria monocytogenes (99% of total listerial population) on raw sliced pork during the chilled storage. This study supports the feasibility of using PLA/SP + Ped film to reduce the initial load of L. monocytogenes on the surface of raw pork.     

S-Scheme α-Fe2O3/TiO2 Photocatalyst with Pd Cocatalyst for Enhanced Photocatalytic H2 Production Activity and Stability

Catalysis Letters - In this work, hematite with titanium dioxide (α-Fe2O3/TiO2) heterojunctions with palladium (Pd) nanoparticles were synthesised to improve efficiency of photocatalytic...     

Short- and long-term fouling characteristics of reverse osmosis membrane at full scale leachate treatment plant

This research is focused on characterizing the foulants on a reverse osmosis (RO) membrane taken from a full-scale leachate treatment plant in Thailand. The system consists of a physico-chemical pre-treatment unit and RO system and has been in operation for 2 years. Ferric chloride (FeCl(3)) was added to the open-jet sedimentation tank at 2.0-2.5 g/l dosage for chemical coagulation. The supernatant from the sedimentation tank was polished using a pressurized sand filter prior to entering the RO system. The RO unit consists of seven pressurized vessels and 42 membrane elements (6 elements in each vessel). The recovery ratio and operating pressure in the RO system were maintained at 50% and 1.5-2.5 MPa. Fouled membranes obtained from short-term (6 months) and long-term operation (2 years) were taken from the system and analyzed by autopsy and sequential cleaning methods. The analysis of foulants on the membrane surfaces revealed that Fe deposits at 3.11 g/m(2). For short-term operated membranes, water cleaning could recover 32.14 and 7.45% of initial pure water flux on the 1st and 6th membrane elements. NaOH cleaning, however, recovered more than 90% of initial flux, much higher than that of HCl solution in both elements. For long-term operated membranes, pure water flux recovery was below 5% for both 1st and 6th elements. Sequential cleaning by NaOH followed by HCl yielded the best results. Nevertheless, flux recovery through sequential cleaning of long-term operated membranes was only 35.3 and 19.1% for the 1st and the 6th elements, respectively.     

Fast Ce,Ca:LuAG scintillation ceramics for HEP: Fabrication,characterization, and computation

High-energy physics community is looking for a hard, fast, and low-cost scintillation material, and Ce:Lu₃Al₅O₁₂ (Ce:LuAG) ceramic is one of the competitive candidates. This work presents Ce,Ca:LuAG scintillation ceramics with good optical quality, and the influence of Ce and Ca concentrations on optical and scintillation properties was fully analyzed. At relatively low level of Ce concentration, the less Ca²⁺ content is needed to achieve a significant intensity increase in fast scintillation component while maintaining a relatively high light yield (LY). The introduction of only 0.1 at% Ca²⁺ could increase the LY_{0.5 μs}/LY_{3.0 μs} from 79.9% to 96.1% in Ce,Ca:LuAG ceramics of 0.1 at% Ce. First-principles investigations are further performed to reveal the tuning mechanisms of the scintillation properties of LuAG by Ce and Ca codoping. We show that the Fermi level shifts down with Ca codoping, which increases the Ce⁴⁺ content and decreases the depth of the electron traps (V_O), resulting to a faster decay. Moreover, the formation preference of Ca-V_O complexes over Ce-V_O leads to the suppression of the non-radiative decay of Ce via V_O. In summary, our study demonstrates the realization of the performance tuning of LuAG via Ce and Ca codoping.