A computed spin-polarized transmission coefficient in zero bias reveals that resonant tunneling near the Fermi level occurs through some molecular orbitals of majority spin only. Thus, for low bias voltages, a spin-filtering effect such as only one spin component contributing to the conductance is expected. This effect would persist even with inclusion of additional electron correlations. c 2009 American Institute of Physics. [DOI: 10.1063/1.3072789]“
“A new dipyranocoumarin, -hydroxytomentolide A (1) was isolated from the leaves of Calophyllum apetalum together with the known compounds

friedelin (2), apetalactone (3), inophyllum C (4) and canophyllol (5). The structure of the new compound was established by spectroscopic studies which include H-1 NMR, C-13 NMR, NOESY, HetCOSY, COLOC experiments and single crystal X-ray see more diffraction analysis.”
“The antioxidant and the tyrosinase inhibitory activities of 4 different solvents (acetone, ethanol, methanol, and water) for preparation of extracts from guava (branch, fruit,

leaf, and seed) were evaluated by measuring total phenolic contents (TPC), DPPH radical scavenging activity, ABTS radical scavenging activity, reducing power (RP), and tyrosinase inhibitory PND-1186 molecular weight activity. The extracts of branch and leaf showed relatively higher antioxidant properties than those of fruit and seed. The highest TPC (141.28 mg/g gallic acid equivalents), DPPH radical scavenging selleck screening library activity (IC(50)= 34.01 mu g/mL), ABTS radical scavenging activity (IC(50)= 3.23 mu g/mL), and RP (IC(50)= 75.63 mu g/mL) were found in acetone extract of leaf, while water extract of seed had the lowest antioxidant activity. The tyrosinase inhibitory activity of ethanol extract from guava leaf was 69.56%, which was the highest activity among the extracts. These results indicate that useful bioactive substances exist in the guava branch as well as leaf extracts.”
“Wide band gap metal oxide semiconductors such as zinc oxide (ZnO) show visible band photolysis that

has been employed, among others, to degrade harmful organic contaminants into harmless mineral acids. Metal oxides show enhanced photocatalytic activity with the increase in electronic defects in the crystallites. By introducing defects into the crystal lattice of ZnO nanoparticles, we observe a redshift in the optical absorption shifting from the ultraviolet region to the visible region (400-700 nm), which is due to the creation of intermediate defect states that inhibit the electron hole recombination process. The defects were introduced by fast nucleation and growth of the nanoparticles by rapid heating using microwave irradiation and subsequent quenching during the precipitation reaction. To elucidate the nature of the photodegradation process, picosecond resolved time correlated single photon count (TCSPC) spectroscopy was carried out to record the electronic transitions resulting from the de-excitation of the electrons to their stable states.