High piezoelectric actuation response in graded Nd2O3 and ZrO2 doped BaTiO3 structures

High electromechanical strains have been developed in this study in Barium Titanate ceramics, suitably doped with Nd and Zr to form a controlled concentration gradient, leading to a dome-like structure on sintering. Compacted pellets constituted of layers of barium titanate powder of varying minor amounts of Nd and Zr powders, incorporated as nitrates precursors, acquire this dome shape on sintering at 1300?C1320^oC and cooling to the ambient temperature, the result of the residual thermoelastic strain. The dome structures exhibit high electromechanical responses, and the piezoelectric coefficients (deduced from electric field induced strains measurements in dome-up and dome-down positions) are also found to be exceptionally high. These Nd and Zr doped barium titanate structures could find applications as an environmentally benign material for fabrication of high displacement functionally graded electromechanical actuators in a single sintering step process.     

Stress induced crystallization of hydrogenated amorphous silicon

Hydrogenated amorphous silicon films were grown on to thermally oxidized silicon wafers by Radio Frequency magnetron sputtering, and SiN_x and Al₂O₃ capping layers were used to control the residual thermal stress. After annealing, a comparison of the silicon films with and without capping layers indicates that tensile stress induced by the capping layer enhances the crystallinity of the annealed amorphous silicon film. The stress is due to the mismatch between the coefficients of thermal expansion for the capping layer and amorphous silicon film. These results highlight the potential of thermal stress as a means to alter the crystallization in thin film architectures and suggest that even larger effects can be obtained with suitable choices of capping layer chemistry.     

Upper bounds on the symbol-error probability of MPSK with phase error using pawula F-function IV

This letter presents an alternative derivation of the Case IV of Pawula F-function and an approximation for the corresponding probability density function (pdf) in the presence of the Tikhonov distributed phase error. The pdf of Case IV is used to obtain new upper bounds for the conditional and average symbol-error probabilities of M-ary phase shift keying with phase error over additive white Gaussian noise channels. Numerical results demonstrate the validity of the upper bounds.     

Expression characteristics of the maeA and maeB genes by extracellular malate and pyruvate in Escherichia coli

The malate-pyruvate conversion pathway is catalyzed by two malic enzyme isomers, MaeA and MaeB. qRT-PCR was carried out under malate and pyruvate supplemented conditions to understand the dynamics of maeA and maeB gene expression. maeA expression was elevated by malate, and maeB expression was inhibited by levels of both malate and pyruvate higher than 0.1 mM. Green fluorescent protein (GFP) reporter plasmids were also constructed by integration of the maeA/maeB promoter with the gfp gene. We showed that maeA driven GFP expression was positively and negatively correlated with extracellular malate and pyruvate induction. In contrast, no significant changes in maeB driven GFP expression were observed under both malate and pyruvate supplemented conditions.     

Enhanced transdermal deposition and characterization of quercetin-loaded ethosomes

We sought to evaluate the transdermal permeation potential of quercetin-loaded ethosomes. Quercetinloaded ethosomes were prepared and characterized with regard to particle size, loading efficiency, stability, and in vitro skin permeation. The optimized formulation of ethosomes was confirmed using 2% egg phosphatidylcholine and hydrated 20% ethanol. After quercetin was applied using this formulation, the stability of the ethosomes was determined when loaded with up to 0.04% quercetin. We observed that loading efficiency was improved with increasing concentrations of quercetin. Ethosomes loaded with 0.04% quercetin showed both the greatest loading efficiency (63.9%±6.0%) and an optimal size range (132±32 nm). Ethosomes loaded with quercetin were superior in skin permeation ability (29.5±7.0 μg/cm²) compared to either ethanolic solution or liposomes. Therefore, we concluded that quercetin-loaded ethosomes increased the skin delivery of quercetin. Our results suggest that quercetin-loaded ethosomes may enhance the effect of cosmetic materials.     

Anti-inflammatory effects of silkworm hemolymph on lipopolysaccharide-stimulated macrophages

Macrophages participate in several inflammatory pathologies such as sepsis and arthritis. We investigated the effect of silkworm hemolymph (SH) on the LPS-induced pro-inflammatory macrophages. SH inhibits LPS-induced nitric oxide (NO) production in RAW 264.7 cells and murine peritoneal macrophages. The decreased NO was reflected as a decreased amount of inducible nitric oxide synthase (iNOS) mRNA and protein. It was also found that SH inhibited pro-inflammatory cytokines, IL-1β, IL-6, and TNF-α production. To elucidate the mechanism by which SH inhibits NO production and iNOS expression, we investigated that SH suppressed IκB phosphorylation, which leads to the activation of NF-κB followed by degradation of IκB. This observation suggests that SH is a potential therapeutic modulator for inflammation-associated disorders.     

Selective hydrogenation of 4-isobutylacetophenone over a sodium-promoted Pd/C catalyst

The effect of sodium promotion on the selective hydrogenation of 4-isobutylacetophenone, 4-IBAP, was investigated over a Pd/C catalyst. A precipitation and deposition method was used to prepare the catalyst, and sodium was promoted on the Pd/C catalyst via post-impregnation while varying the sodium content. The sodium-promoted Pd/C catalyst resulted in a significantly improved yield greater than 96% of the desired product, 1-(4-isobutylphenyl) ethanol (4-IBPE), compared with the non-patented literature results under a mild hydrogenation condition. A detailed hydrogenation network over the Pd/C catalyst was suggested. The reaction mechanism for the yield and selectivity enhancement of 4-IBPE induced-by the promoted Pd/C was elucidated in relation to the geometric and electronic effects of reactant molecules in the microporous support depending on the reaction steps.     

Synthesis of polyethylene glycol-polystyrene core-shell structure particles in a plasma-fluidized bed reactor

Particles with core-shell structure with polystyrene (PS) core and polyethylene glycol (PEG) grafted on the surface were synthesized in a plasma-fluidized bed reactor. The virgin, plasma-treated, and grafted powders were characterized by the DPPH method, UV-vis spectrophotometer, NMR, FT-IR and SEM. The plasma-treated PS powders have well formed peroxide on the surface. By PEG grafting polymerization, PEG is well grafted and dispersed on the surface of the plasma-treated PS powders. The PEG-g-PS powder exhibits the core shell structure in the cross-sectional SEM image, and it can be claimed that well dispersed PEG grafting polymerization on PS surface can be achieved in the plasma fluidized bed reactor.     

The effect of rear surface polishing to the performance of thin crystalline silicon solar cells

As the thickness of crystalline silicon solar cells decreases, light loss cannot be avoided due to the absorption limit in long wavelength light. Internal rear side reflection can be enhanced by polishing the rear surface. The rear polishing processes are performed before the texturing and before and after doping the emitter layer to optimize the solar cell fabrication process sequences. All cells made by rear surface polishing showed improved light trapping in long wavelength region (900-1100 nm) compared to that in the conventional cells. However, silicon solar cells fabricated by rear polishing before and after doping have similar (35.5 mA/cm²) or lower (35.26 mA/cm²) short circuit current density compared to the cells produced by the conventional process (35.59 mA/cm²) due to pore damage to the anti-reflection layer and the surface of the emitter layer during rear polishing. This surface damage was effectively prevented adapting the rear surface polishing before the front surface texturing, which led to increasing the current density from 35.59 to 36.29 mA/cm².