Effect of fermentation by Bacillus subtilis on antioxidant and cytotoxic activities of black rice bran

Black rice bran was fermented with Bacillus subtilis KU3 isolated from Korean traditional food, Kimchi. Antioxidant and cytotoxic activities of the fermented black rice bran were investigated. Total phenolic and anthocyanin contents decreased from 171.54 mg GAE g^?1 and 2.31 mg g^?1 to 139.13 mg GAE g^?1 and 2.12 mg g^?1, respectively, after fermentation. Antioxidant activities determined by 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, β‐carotene bleaching and ferric thiocyanate assay were correlated with total phenolic and anthocyanin contents. Non‐fermented black rice bran extract (NFBE) showed greater antioxidant activities than fermented black rice bran extract (FBE). Cytotoxic activities measured by MTT assay showed that both NFBE and FBE had over 50% activities. The cytotoxic activities of FBE against MCF‐7 and HeLa cells were 71.65% and 68.07%, respectively, at 8.0 mg mL^?1, but those of NFBE were lower than 50%. These results suggested that the cytotoxic activity of black rice bran improved through fermentation, while antioxidant activity reduced.     

Optimal location of basin‐wide constructed washlands to reduce risk of flooding

A washland can effectively reduce peak flow of a high flow event at a certain location. A number of washlands located in a basin influence each other's hydrological function, and hence, their hydrological role should be evaluated from a river network perspective. Here, we present an approach to determine optimal locations of constructed washlands in a basin, considering their mutual effect. The problem is formulated as a multiobjective problem with maximizing peak flow reduction effect as one objective and minimizing the total volume of washlands, which is associated with cost, as another. By simplifying modelling algorithm for hydrological routing, we show that consideration of all possible cases is feasible for the situation of a typical basin. This approach guarantees global optimum and shows a full spectrum of Pareto front, which will help decision‐makers in problems of multiple objective functions. The proposed approach is demonstrated for the Anseong River basin.     

TiO2 nanotube branched tree on a carbon nanofiber nanostructure as an anode for high energy and power lithium ion batteries

The inherently low electrical conductivity of TiO2-based electrodes as well as the high electrical resistance between an electrode and a current collector represents a major obstacle to their use as an anode for lithium ion batteries. In this study, we report on high-density TiO2 nanotubes （NTs） branched onto a carbon nanofiber （CNF） ＂tree＂ that provide a low resistance current path between the current collector and the TiO2 NTs. Compared to a TiO2 NT array grown directly on the current collector, the branched TiO2 NTs tree, coupled with the CNF electrode, exhibited -10 times higher areal energy density and excellent rate capability （discharge capacity of -150 mA.h.g-1 at a current density of 1,000 mA·g-1）. Based on the detailed experimental results and associated theoretical analysis, we demonstrate that the introduction of CNFs with direct electric contact with the current collector enables a significant increase in areal capacity （mA·h·cm-2） as well as excellent rate capability.     

Gas Sensors Based on Piezoelectric Micro-Diaphragm Transducer

ABSTRACT

We have fabricated high sensitive gas sensor based on piezoelectrically driven micro-diaphragm transducers. The micro-diaphragm transducer was fabricated using micro-electro-mechanical-system (MEMS) technique. The diol based sol-gel derived Pb(Zr_0.52,Ti_0.48)O₃(PZT) film was used as a piezoelectric actuating layer. We have used the resonant frequency change of micro-diaphragm transducer upon mass increase as a sensing signal. The resonant frequency values were measured by analysis of electrical signals from the micro-diaphragm transducer. The fundamental resonant frequency of the micro-diaphragm was in the range of 250 to 360 kHz, depending on their physical boundary conditions. The mass sensitivity of bare micro-diaphragm transducer was 66.5 Hz/ng. Two polymer sensing layers such as the polymethylmethacrylate (PMMA) and polydimethylsiloxane (PDMS) films were used to estimate the gas sensing behavior of microtransducers for various vapors of organic compounds. PMMA was used to detect primary alcohols while PDMS was used for toluene and benzene. The resonant frequency of micro-diaphragm transducer was shifted toward lower frequency range as the vapor concentration increased. With PMMA gas sensing layer, the micro-diaphragm showed a gas sensitivity of 0.456 Hz/ppm for ethanol vapor. When the PDMS gas sensing layer was used, the micro-diaphragm showed a gas sensitivity of 0.143 Hz/ppm for toluene vapor. When the test vapors were removed from the reaction chamber, the resonant frequencies of micro-diaphragm sensors were completely recovered to their initial state.     

Relationship between downstream hydraulic geometry and suspended sediment concentration characteristics

The downstream hydraulic geometry relationships, i.e., the downstream variation of the water surface width W, the hydraulic depth H, and the mean velocity V at a constant flow frequency, represent the adaptation of channel geometry and flow dynamics to a given hydrological regime. It has been reported that W, H, and V all tend to increase in the downstream direction for most natural rivers but their increasing rates show relative differences. It is widely known that most natural rivers exhibit W increasing at a greater rate compared to H, indicating the formation of wide and shallow rivers. Nevertheless, rivers showing the opposite to this trend, i.e., H increases at a rate greater than that of W, have also been observed. We investigated four rivers in this study where two of them (the Kansas River and the Tennessee River) show greater increasing rate of W than that of H and the other two (the Mississippi River and the Nakdong River) show the opposite. We found that the two types of rivers show different spatial patterns in their relationships between suspended sediment concentration (C) and flow discharge (Q). Essentially, rivers with a greater increasing rate of W (i.e., the Kansas and the Tennessee) show C-Q relationships lagged in the downstream direction. On the other hand, rivers with a smaller increasing rate of W (i.e., the Mississippi and the Nakdong) show C-Q relationships that are aligned along the downstream direction. Considering that the flow discharge increases downstream in general, the rivers showing the aligned C-Q relationships are exposed to greater imbalance of spatial distribution of sediment fluxes, and hence supposed to be less stable compared to the other type of rivers.