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Index Abstracts     

The Fokker-Planck equation for arbitrary nonlinear noise

We present the Fokker-Planck equation for arbitrary nonlinear noise terms. The white noise limit is taken as the zero correlation time limit of the Ornstein-Uhlenbeck process. The drift and diffusion coefficients of the Fokker-Planck equation are given by triple integrals of the fluctuations. We apply the Fokker-Planck equation to the active rotator model with a fluctuating potential barrier which depends nonlinearly on an additive noise. We show that the nonlinearity may be transformed into the correlation of linear noise terms.     

Accelerated hydrolysis of esters catalyzed by receptors, I nonenzymatic cleavage ofp-nitrophenyl acetate by polypeptides

The hydrolysis kinetics ofp-nitrophenyl acetate by basic polypeptides with a variety of amino acid residues were analyzed. The results suggest that the tertiary structure of microenvironment brought about by random coil assembly is more important as a binding site than the number of basic residues (catalytic sites).     

Palladium(II)-catalyzed epoxidation of olefins with α-silyloxyalkyl peroxybenzoates

A novel oxygen-atom-transfer 2-reaction from α-silyloxyalkyl peroxybenzoate to olefins by palladium(II) catalyst to give epoxides has been described.     

The growth of the flower-like ZnO structure using a continuous flow microreactor

ZnO is a valuable material for display devices, for catalytic chemical reactors, and as sorbents for desulfurizaton because of its excellent chemical and thermal stability. In this work, we report the synthesis of flower-like ZnO structures using a continuous flow microreactor over an oxidized silicon substrate. A chemical solution that employed zinc acetate [Zn(CH₃COO)₂ · 2H₂O] and sodium hydroxide [NaOH] was used as precursors. The effects of water bath temperature, impinging time and concentration of NaOH on the growth of the flower-like structure have been investigated in this study. It was confirmed that the size of the fabricated flower-like structure was increased as the impinging time and the water bath temperature were increased. Various flower-like morphologies were observed according to the different concentration of NaOH. Scanning electron microscope (SEM) was used to study the morphologies of the synthesized flower-like ZnO structures. X-ray diffraction (XRD) was used to characterize the crystal structures of the ZnO crystallites as a function of the concentration of sodium hydroxide.     

Probing pores using elementary quantum mechanics.

The relaxation of polarized spins in a porous medium has been utilized as a probe of its structure. We note that the governing diffusion problem has a close parallel to that of a particle in a box, an elementary Quantum mechanics toy model. Following the spirits of "free electron" model, we use generic properties of the eigen spectrum to understand features common to a wide variety of pore geometry, consistent with large scale numerical simulations and experimental data.     

Synthesis of CaWO<Subscript>4</Subscript> nanocolloidal suspension via pulsed laser ablation and its optical properties

Pulsed laser ablation (PLA) in the liquid phase was successfully employed to synthesize calcium tungstate (CaWO₄) nanocolloidal suspension. The crystalline phase, particle morphology and laser ablation mechanism for the colloidal nanoparticles were investigated using XRD, TEM and SEM. The obtained colloidal suspension consisted of well-dispersed CaWO₄ nanoparticles which showed a spherical shape with sizes ranging from 5 to 30 nm. The laser ablation and the nanoparticle forming process were discussed under consideration of the photo-ablation mechanism, where the nanoparticles were generated by rapid condensation of the plume in high pressured ethanol vapor. The optical properties of the prepared CaWO₄ colloidal nanoparticles were analyzed in detail using XPS, Raman spectroscopy, UV-Vis spectroscopy and PL spectrophotometry. The optical band gap was estimated by Tauc and Menths law. PACS 42.62.-b; 82.70.Dd; 78.55.Hx; 81.07.Wx     

Room-temperature laser deposition of GaAs nanocrystals on PMMA microspheres using particle fluidization

A modified pulsed laser deposition (PLD) was successfully employed to deposit GaAs nanocrystals on the surface of PMMA (polymethylmethacrylate) microspheres. This novel approach is distinguished by the fact that laser ablated materials are deposited uniformly onto the surface of spherical particles that are held constantly in a particle fluidization unit. The XRD, SEM, EDX, TEM, EDP, and XPS results confirmed that cubic structured GaAs nanocrystals was deposited uniformly on the surface of PMMA microspheres with an average diameter of about 15 nm. PACS 81.15.Fg; 78.55.Cr; 82.35.Np