86% TMR at 4.2 K for Amorphous Magnetic-Tunnel-Junctions with Co_(60)Fe_(20)B_(20) as Free and Pinned Layers

Single barrier magnetic-tunnel-junctions (MTJs) with the layer structure of Ta(5)/Cu(30)/Ta(5)/Ni79Fe21(5)/Ir22 Mn78(12)/Co60Fe20B20(4)/Al(0.8)-oxide/Co60Fe20B20(4)/Cu(30)/Ta(5) [thickness unit: nm] using the amorphous Co60Fe20B20 alloy as free and pinned layers were micro-fabricated. The experimental investigations showed that the tunnel magnetoresistance (TMR) ratio and the resistance decrease with increasing dc bias voltage from 0 to 500 mV or with increasing temperature from 4.2 K to RT. A high TMR ratio of 86.2% at 4.2 K, which corresponds to the high spin polarization of Co60Fe20B20, 55%, was observed in the MTJs after annealing at 270℃ for 1 h. High TMR ratio of 53.1%, low junction resistance-area product RS of 3.56 kΩμm2, small coercivity HC of ≤4 Oe, and relatively large bias-voltage-at-half-maximum TMR with the value V1/2 of greater than 570 mV at RT have been achieved in such Co-Fe-B MTJs.

Uniform and Homogeneous Growth of Copper Nanoparticles on Electrophoretically Deposited Carbon Nanotubes Electrode for Nonenzymatic Glucose Sensor

The multiwalled carbon nanotubes thin-film-based electrode was fabricated by electrophoretic deposition and modified with copper （Cu） nanoparticles to fabricate Cu/CNTs nanocomposite sensor for nonenzymatic glucose detection. The expensive glassy carbon electrode was replaced by fluorine-doped tin oxide glass containing CNTs film to confine the Cu nanoparticles growth by electrodeposition through cyclic voltammetry （CV）. The ultraviolet visible and X-ray diffraction analysis revealed the successful deposition of Cu nanoparticles on the CNTs-modified electrode. The atomic force microscopy images confirrqed the morphology of electrodeposited Cu on CNTs film as uniformly dispersed particles. The electrocatalytic activity of electrode to the glucose oxidation was investigated in alkaline medium by CV and amperometric measurements. The fabricated sensor exhibited a fast response time of less than 5 s and the sensitivity of 314 μA rnM^-1 cm^-2 with linear concentration range （0.02-3.0 mM） having detection limit 10.0 μM. Due to simple preparation of sensor, Cu/CNTs nanocomposite electrodes are a suitable candidate for reliable determination of glucose with good stability.

Antibacterial Action of Chemically Synthesized and Laser Generated Silver Nanoparticles against Human Pathogenic Bacteria

Silver nanoparticles in the range of 10-40 nm were synthesized chemically and by laser ablation, em- ployed for in vitro antibacterial action against human pathogenic bacterium. Their formation was evidenced by UV-visible spectrophotometer; particle size confirmed by atomic force microscopy, crystal structure determined by X-ray diffraction and chemical composition investigated by Fourier transform infrared spec- troscopy. The calculated MIC （minimum inhibitory concentration） of chemically synthesized nanoparticles with 30-40 nm in size are 2.8 μg/mL 4.37 μg/mL 13.5μg/mL and 2.81 p.g/mL for E. coil, S. aureus, B. subtillis and Salmonella, respectively. Whereas laser ablated nanoparticles exhibit MIC of 2.10 μg/mL 2.36 μg/ mL and 2.68 μg/mL for E. coli, S. aureus and Salmonella, respectively.

Antibacterial Behavior of Laser-Ablated Copper Nanoparticles

Copper nanoparticles（Cu NPs） have been synthesized by using laser ablation method,using deionized water as main solvent.The formation of Cu NPs is confirmed by UV-visible spectrophotometer（UV-Vis）,atomic force microscopy（AFM） and X-ray diffraction（XRD）.Cu NPs fabricated by laser ablation have diameter in the range from 14 to 55 nm.Structural analysis revealed the face-centered cubic（fcc） crystal structure of Cu NPs.The antibacterial activity of Cu NPs has been evaluated in vitro against strains of Escherichia coli（E.coli） and Staphylococcus aureus（5.aureus）.The fabricated Cu NPs show considerable antibacterial activity against both bacterial strains.The bacterial activity of Cu NPs was found to depend on the microbial species.