Quantum Conductance Probing of Oxygen Vacancies in SrTiO3 Epitaxial Thin Film using Graphene

Quantum Hall conductance in monolayer graphene on an epitaxial SrTiO₃ (STO) thin film is studied to understand the role of oxygen vacancies in determining the dielectric properties of STO. As the gate‐voltage sweep range is gradually increased in the device, systematic generation and annihilation of oxygen vacancies, evidenced from the hysteretic conductance behavior in the graphene, are observed. Furthermore, based on the experimentally observed linear scaling relation between the effective capacitance and the voltage sweep range, a simple model is constructed to manifest the relationship among the dielectric properties of STO with oxygen vacancies. The inherent quantum Hall conductance in graphene can be considered as a sensitive, robust, and noninvasive probe for understanding the electronic and ionic phenomena in complex transition‐metal oxides without impairing the oxide layer underneath.     

Electrical characteristics of Si-nanoparticle/Si-nanowire-based field-effect transistors

In this study, Si-nanoparticle(NP)/Si-nanowire(NW)-based field-effect transistors (FETs) with a top-gate geometry were fabricated and characterized. In these FETs, Si NPs were embedded as localized trap sites in Al₂O₃ top-gate layers coated on Si NW channels. Drain current versus drain voltage (I _DS−V _DS) and drain current versus gate voltage (I _DS−V _GS) were measured for the Si NP/Si NW-based FETs to investigate their electrical and memory characteristics. The Si NW channels were depleted at V _GS = 9 V, indicating that the devices functioned as p-type depletion-mode FETs. The top-gate Si NW-based FETs decorated with Si NPs show counterclockwise hysteresis loops in the I _DS−V _GS curves, revealing their significant charge storage effect.     

Evaluation of Ba0.5Sr0.5Co0.8Fe0.2O3−δ as a potential cathode for an anode-supported proton-conducting solid-oxide fuel cell

The potential application of Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCF) as a cathode for a proton-conducting solid-oxide fuel cell based on BaCe_0.9Y_0.1O_2.95 (BCY) electrolyte was investigated. Cation diffusion from BCY to BSCF with the formation of a perovskite-type Ba²⁺-enriched BSCF and a Ba²⁺-deficient BCY at a firing temperature as low as 900 °C was observed, the higher the firing temperature the larger deviation of the A to B ratio from unit for the perovskites. Symmetric cell tests demonstrated the impurity phases did not induce a significant change of the cathodic polarization resistance, however, the ohmic resistance of the cell increased obviously. Anode-supported cells with the electrolyte thickness of ∼50 μm were successfully fabricated via a dual-dry pressing process for the single-cell test. Under optimized conditions, a maximum peak power density of ∼550 and 100 mW cm⁻² was achieved at 700 and 400 °C, respectively, for the cell with the BSCF cathode layer fired from 950 °C. At 500 °C, the ohmic resistance is still the main source of cell resistance. A further reduction in membrane thickness would envisage an increase in power density significantly.     

Solid-oxide fuel cell operated on in situ catalytic decomposition products of liquid hydrazine

Hydrazine was examined as a fuel for a solid-oxide fuel cell (SOFC) that employed a typical nickel-based anode. An in situ catalytic decomposition of hydrazine at liquid state under room temperature and ambient pressure before introducing to the fuel cell was developed by applying a Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3−δ (BSCF) oxide catalyst. Catalytic testing demonstrated that liquid N₂H₄ can be decomposed to gaseous NH₃ and H₂ at a favorable rate and at a temperature as low as 20 °C and H₂ selectivity reaching values as high as 10% at 60 °C. Comparable fuel cell performance was observed using either the in situ decomposition products of hydrazine or pure hydrogen as fuel. A peak power density of ∼850 mW cm⁻² at 900 °C was obtained with a typical fuel cell composed of scandia-stabilized zirconia and La_0.8Sr_0.2MnO₃ cathode. The high energy and power density, easy storage and simplicity in fuel delivery make it highly attractive for portable applications.     

Prevention of ethanol-induced hepatotoxicity by fermented Curcuma longa L. in C57BL/6 mice

The protective effect of fermented Curcuma longa L. (FC) was investigated in male C57BL/6 mice under ethanol-induced oxidative stress. Ethanol markedly elevated levels of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in mice. However, mice receiving FC prior to ethanol treatment did not display hepatotoxicity as evidenced by the significant reductions of AST and ALT activities. When compared to the ethanol-alone treated group, FC group exhibited a significant decrease in cytochrome P-450 2E1 (CYP2E1) activity, an enzyme associated with oxidative stress. Indicators of the hepatic antioxidant defense system, such as levels of superoxide dismutase, catalase, glutathione reductase and glutathione were also increased in FC-pretreated mice. The amelioration of malondialdehyde was indicative of the protective effect of FC against liver damage mediated by ethanol. These results suggest that FC could be a candidate used for the prevention against alcoholic liver diseases by the alleviation of oxidative stress via suppressing CYP2E1.     

Thermal characterization and morphological study of polyphenylene sulfide–polycarbonate blends

The thermal behavior and phase morphology of binary blends of poly(phenylene sulfide) (PPS) with polycarbonate (PC) have been investigated. Differential scanning calorimetry and dynamic mechanical thermal analysis indicate the blends are immiscible, but the glass transition temperature of PC in the blends was found to be decreased due to the degradation of the PC. The PC degradation was investigated by measuring the molecular weight of PC extracted from the blends. Rheological properties of the blends were also studied using a rheodynamic spectrometer. An inversion of the phase morphology was observed from the scanning electron microscopy and dynamic mechanical thermal analysis. The increase of crystallinity of the PPS in the blends was found from a DSC study.     

Plasmonic‐Tuned Flash Cu Nanowelding with Ultrafast Photochemical‐Reducing and Interlocking on Flexible Plastics

Herein, a high‐performance copper nanowire (Cu NW) network (sheet resistance ≈ 17 Ω sq^?1, transmittance 88%) fabricated by plasmonic‐tuned flash welding (PFW) with ultrafast interlocking and photochemical reducing is reported, which greatly enhance the mechanical and chemical stability of Cu NWs. Xenon flash spectrum is tuned in an optimized distribution (maximized light intensity at 600 nm wavelength) through modulation of electron kinetic energy in the lamp by generating drift potential for preferential photothermal interactions. High‐intensity visible light is emitted by the plasmonic‐tuned flash, which strongly improves Cu nanowelding without oxidation. Near‐infrared spectrum of the flash induced an interlocking structure of NW/polyethylene terephthalate interface by exciting Cu NW surface plasmon polaritons (SPPs), increasing adhesion of the Cu nanonetwork by 208%. In addition, ultrafast photochemical reduction of Cu NWs is accomplished in air by flash‐induced electron excitations and relevant chemical reactions. The PFW effects of localized surface plasmons and SPPs on junction welding and adhesion strengthening of Cu network are theoretically studied as physical behaviors by finite‐difference time‐domain simulations. Finally, a transparent resistive memory and a touch screen panel are demonstrated by using the flash‐induced Cu NWs, showing versatile and practical uses of PFW‐treated Cu NW electrodes for transparent flexible electronics.     

Isolation of antioxidant with exercise enhancing potential from Pseudosasa japonica leaves

An antioxidative compound with effective exercise-enhancing potential was isolated from the ethanolic extract of Pseudosasa japonica leaves. The ethanolic extract was partitioned in the order of hexane, chloroform, ethyl acetate, and water. Of the 4 fractions, the ethyl acetate-fraction (PJE-E) showed profound scavenging activity on superoxide anion- and ABTs cation radicals. Thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) were conducted to isolate a compound with antioxidative activity on exercise endurance capacity from the PJE-E. The structure of the resulting compound was identified as ferulic acid by ¹H/¹³C nuclear magnetic resonance (NMR). This ferulic acid was orally administered to mice for 18 days and its effect on exercise endurance capacity was investigated using an adjustablecurrent water pool. Compared to the control group, a 1.8 fold increase in swimming time was observed in the ferulic acid-administered mice. Results indicate that ferulic acid from P. japonica leaves might contribute to the potent exercise-enhancing effect.     

Effect of thermal-softening in rod impact test for the determination of dynamic material properties of polycarbonate

A theory was developed to investigate the effect of thermal-softening in rod impact test for the determination of the dynamic material properties of Polycarbonate, on the basis of one-dimensional shock wave propagation phenomena. High velocity rod impact test was performed with flat-ended cylindrical rod specimens. From the geometrical measurements of deformed rod, dynamic material properties were determined by both previous theories and the theory suggested in this work. The variation of temperature rise due to adiabatic plastic deformation with impact velocities and the effect of thermal-softening on the dynamic yield stress were analyzed.