Ameliorating effects of a nopal (Opuntia ficus-indica) complex on blood glucose in db/db mice

This study investigated the effects of a nopal (Opuntia ficus-indica) complex (OF) on blood glucose metabolism in db/db mice for 4 weeks. Food and water intake significantly decreased in OF-treated mice compared to controls (p<0.05). In addition, blood glucose and plasma insulin levels were significantly reduced in the OF-treated group compared to the controls (p<0.05). Histopathological analysis showed that the morphology of pancreatic islets was improved in the OF-treated db/db mice. Immunohistochemistry of the pancreatic islets showed that insulin production and the number of β-cells apparently increased.     

A new correlation and the review of two-phase flow pressure change across sudden expansion in small channels

In this study, the authors first present a short overview on the single-phase flow across sudden expansion, followed by a thorough review of the relevant literature for two-phase flow across sudden expansion, and examination of the applicability of the existing correlations. Also, 282 data available from five publications are collected. It is found that none of the existing correlations can accurately predict the entire database. Most of the correlations highly over predict the data with a mini test section which has a Bond number being less than 0.1 in which the effect of surface tension dominates. Also, some of the correlations significantly under predict the data for very large test sections. Among the models/correlations being examined, the homogeneous model shows a poor predictive ability than the others, but it is handy for the engineering aspect. Hence by taking account the influences of Bond number, Weber number, Froude number, liquid Reynolds number, gas quality and area ratio into the original homogeneous model, a modified homogeneous model is proposed that considerably improves the predictive ability over existing correlations with a mean deviation of 23% and a standard deviation of 29% to all the data with wider ranges of operating parameters for application.     

Application of an in situ bismuth-coated glassy carbon electrode for electroanalytical determination of Cd (II) and Pb (II) in Korean polished rices

Rapid on-site monitoring of heavy metals in plants is necessary to minimize the exposure of humans to the contaminated food. The potential of using anodic stripping voltammetry (ASV) for simultaneous determination of cadimium (Cd) and lead (Pb) in rice was evaluated. Eight different Korean polished rices were digested using concentrated HNO₃ solution in a microwave oven. The peak currents measured with an in situ bismuth-coated electrode were linearly proportional to Cd and Pb concentrations (1.5 to 200 ppb) in 0.1 M HNO₃ (R² ⩾0.98). The electrode was feasible for measuring Pb in acid digests of the tested polished rices with measurement errors of <16.3 ppb. However, even though there was acceptable agreement in 4 of the 8 samples tested for Cd between the ASV and inductively coupled argon plasma (ICP) methods, further studies would be needed to improve the predictive capability of the electrode while reducing the variability in measurement and lowering the detection limit.     

Post-growth annealing and wide bandgap modulation of BeZnO layers grown by RF co-sputtering of ZnO and Be targets

ZnO based oxide system Be _x Zn_1−x O alloy of various compositions has been successfully grown by the RF co-sputtering method. The crystallinity of the Be _x Zn_1−x O alloys has been remarkably improved after the post-annealing at 600 °C compared with the Be _x Zn_1−x O alloys post-annealed at other temperatures. The x value of the Be _x Zn_1−x O layers has been increased from 0.022 to 0.17 by adjusting the RF-power of the Be target. Also, the optical bandgap energy has been modulated from 3.2218 to 3.7978 eV, respectively. Based on our results, a bandgap bowing parameter of Be _x Zn_1−x O alloy has been extracted out to be 4.5 eV. These findings could be useful to fabricate the ZnO/Be _x Zn_1−x O quantum structures and bandgap modulation for deep ultraviolet-light-emitting diodes.     

Highly stable RuO2/SnO2 nanocomposites as anode electrocatalysts in a PEM water electrolysis cell

This work explores the opportunity to reduce the cost and enhance the stability of RuO₂ as an oxygen evolution reaction catalyst by coating RuO₂ on chemically stable SnO₂ support. Nano‐sized RuO₂/SnO₂ composites of different mass ratios of RuO₂ to SnO₂ (0.45:1, 0.67:1, and 1.07:1) were synthesized using solution‐based hydrothermal method. The physicochemical properties of the RuO₂/SnO₂ were studied by scanning electron microscopy, X‐ray diffraction, transmission electron microscopy, and N₂ adsorption–desorption isotherms. The electrochemical activity of RuO₂/SnO₂ as anode electrocatalyst was investigated in a proton exchange membrane (PEM) water electrolysis cell of Pt/C cathode and Nafion membrane. Experimental results showed that RuO₂/SnO₂ of ratio (1.07:1) exhibit higher electrochemical activity compared to pure RuO₂, resulting ~50% reduction of noble metal content. The extended life test of electrocatalysts for 240 h implied that RuO₂/SnO₂ (1.07:1) significantly improved the stability of electrode in comparison to pure RuO₂ in oxygen evolution processes. Copyright © 2013 John Wiley & Sons, Ltd.     

Whole cell biotransformation of major ginsenosides using Leuconostocs and Lactobacilli

Various strains of Lactobacillus and Leuconostoc species were evaluated to select the most promising strain to carry out transforming major ginsenosides into minor ginsenosides. Among the experimental lactic acid bacteria (LAB), Leuconostoc mesenteroides KFRI 690, Leuconostoc paramesenteroides KFRI 159, and Lactobacillus delbrueckii KCCM 35486 produced compound K from major ginsenosides precursors (Rb1, Rc, Rd, and F2). KFRI 690 showed the best transforming activity among them. Furthermore, these LABs could biotransform ginsenosides without disrupting the cell to release enzyme activity. The conversion ratio of Rb1 to compound K using KFRI 690 has been enhanced up to 97.8% by adding 2% sucrose into the culture medium. This is the first report on the production of compound K using whole cells of Leu. mesenteroides, Leu. paramesenteroides, and Lb. delbrueckii, which are food grade lactic acid bacteria.     

Molecular weight distributions in terpolymerization of α‐methylstyrene/styrene/acrylic acid in continuous stirred tank reactor

Free‐radical terpolymerization of α‐methylstyrene/styrene/acrylic acid (AMS/ST/AA) in a continuous stirred tank reactor (CSTR) was studied theoretically and experimentally. A series of reactions were conducted to investigate the effect of the reaction temperature, residence time, solvent contents, initiator concentration, chain‐transfer agent level, and different monomer compositions on the molecular weight distribution (MWD). The mathematical model based on “the instantaneous property method (IPM)” and the pseudokinetic rate constant method was introduced and modified to predict the MWD of the bulk terpolymer produced in a CSTR. The effects of process variables were included in the mathematical model. Extensive comparisons were made between the theoretical results and experimental values. The rate of the free‐radical terpolymerization of AMS/ST/AA was comparatively slow and it was found that the concentration of α‐methylstyrene had a strong influence on the molecular weight and polydispersity of the MWD. This presumably reflected the existence of a normal bimolecular termination rate and a slow propagation rate due to steric hindrances at the doubly substituted vinyl carbon atom or transfer of the allylic hydrogen from the α‐methyl group. Good agreement was obtained between calculated MWD and the experimental one by assuming that the disproportionation termination of free radicals was the dominant chain‐stoppage mechanism. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 479–487, 2001