Synthesis of p-type zinc oxide films by plasma-assisted pulsed laser deposition

Heavily acceptor doped zinc oxide (ZnO) films were deposited on quartz substrates by plasma-assisted pulsed laser deposition (PA-PLD) using a non-sintered target heavily doped with phosphorus or copper and radio frequency induction-coupled nitrogen or oxygen plasma (RF-ICP). The p-type ZnO layer was achieved by a nitrogen acceptor dopant using the technique of plasma-assisted nitrogen (PA-N) pulsed laser deposition. Photoluminescence spectra showed a peak from phosphorus- or copper-bound excitons at about 380 nm and a broad, green defect-related band occurring at about 550 nm. Transmission spectra showed a blue shift of the near-band-edge wavelength and a worsening of transmission by heavily copper-doped zinc oxide.     

Au nanorod arrays tailored for surface-enhanced Raman spectroscopy.

We have demonstrated surface-enhanced Raman spectroscopy (SERS) on arrays of Au nanorods aligned in line by a dynamic oblique deposition technique. For light polarized along the major axes of the nanorods, the plasma resonance of the Au nanorods has been tuned to a wavelength suitable for Raman spectroscopy. Raman scattering on the discrete nanorods is significantly enhanced compared with that on semicontinuous Au films. Since the preparation process is physically bottom-up, it is robust in its selection of the materials and is useful for providing SERS sensors at low cost.     

Bridging radial and non-radial measures of efficiency in DEA

Data envelopment analysis (DEA) has been utilized worldwide for measuring efficiencies of banks, telecommunications, electric utilities and so forth. Yet, the existing models have some well-known shortcomings that limit their usefulness. In DEA we have two fundamental approaches to measuring efficiency with very different characteristics; radial and non-radial. We demonstrate a method for linking these two approaches in a unified framework called Connected-SBM (slacks-based measure). It includes two scalar parameters, and by changing the parameter values we can relocate the analysis anywhere between the radial and the non-radial models. An appropriate choice of these parameters can overcome the key shortcomings inherent in the two approaches, namely, proportionality and mixed patterns of slacks.     

Formulation of spectra-based attenuation coefficients in water as a function of depth and off-axis distance for 4, 10 and 15 MV X-ray beams

On the basis of X-ray spectra information for 4, 10 and 15 MV X-rays from a linear accelerator, we propose a method for formulating the attenuation coefficient in water as a function of depth and off-axis distance. It was confirmed by transmission measurement that the formulation provides a good estimation of the attenuation coefficient in water. Using the formulation, we further assessed the effective attenuation coefficient in water as a function of off-axis distance.     

Synthesis and lithium ion insertion/extraction properties of hollandite-type MnO2 prepared by acid digestion of Mn2O3

Single-phase specimens of α-MnO₂ (hollandite-type) and β-MnO₂ (rutile-type) were synthesized by the acid digestion of Mn₂O₃ under reflux conditions. The type of polymorph of MnO₂ products was strongly dependent on the reaction temperature, type of acid used, and its concentration. The pH titration curve of α-MnO₂ displayed a monobasic acid behavior toward Li⁺, but β-MnO₂ showed a poor ion-exchange property. In contrast, both α-MnO₂ and β-MnO₂ acted as a rechargeable active material in a liquid organic electrolyte lithium cell. The initial discharge capacities of both electrodes exceeded 200 mAh/g (cut-off voltage: 2 V). After discharge–charge repetition, the α-MnO₂ structure was still retained without structure collapse, although the β-MnO₂ structure was destroyed. These findings show that Li⁺ ions can be inserted only into the hollandite-type tunnels in α-MnO₂ and cannot diffuse the rutile-type linkages in α-MnO₂ as well as those in β-MnO₂ without structure collapse.     

Exit angle dependence of charge-state distribution of backscattered He ions

Exit angle and energy dependences of the charge-state distribution of backscattered He ions were investigated when 500 keV He⁺ ions were incident on SiO₂. The energy dependence of the He⁺ fraction was estimated by comparing the measured He⁺ spectra with the simulated spectra of He ions in all charge states at the exit angles of 5-25° with respect to the SiO₂ surface. We found that the He⁺ fraction is almost independent of the exit angle at energies higher than 250 keV and the observed energy dependence of the He⁺ fraction is in good agreement with that for the carbon-foil-transmission experiment. In the low energy region (<250 keV), however, the He⁺ fraction decreases as the exit angle decreases.     

Preparation of Aqueous Polyurethane Dispersions Using Aromatic Diisocyanate

Aqueous polyurethane dispersions were prepared by the reaction of hydroxyl-terminated poly(ethylene adipate), ethylene glycol, dimethylol propionic acid and aromaic diisocyante, 4,4′-diphenylmethane diisocyanate. The influence of molecular weight of oligoester and molar ratio between isocyanate and hydroxyl groups (NCO/OH) in the prepolymerization step were investigated. Molecular weight, particle size and particle size distribution were measured and compared. It was verified that the molecular weight increases with increasing in NCO/OH molar ratio. The results suggest that the hard segment content plays an important role in particle size and particle size distribution of the dispersions.     

Isolation and molecular structure of the organo-persulfuranes [12-S-6(C6)

Reactions of bis(2,2'-biphenylylene)sulfuranyl bis(tetrafluoroborate) [(8-S-4(C4)]2+ with organo-lithium reagents (PhLi and MeLi) gave bis(2,2'-biphenylylene)di-C-substituted persulfuranes as a first persulfurane [12-S-6(C6)] having only carbon ligands. These compounds have been characterized by 1H and 13C NMR and mass spectroscopies. The structure of the dimethyl derivative was determined by X-ray crystallographic analysis, revealing that it has a distorted octahedral geometry with the two methyl ligands cis to each other, and subsequently, it was analyzed by an ab initio calculation.     

Self-encapsulation of homogeneous catalyst species into polymer gel leading to a facile and efficient separation system of amine products in the Ru-catalyzed reduction of carboxamides with polymethylhydrosiloxane (PMHS)

A practical procedure for production of amines is offered by the ruthenium-catalyzed reduction of carboxamides with polymethylhydrosiloxane, in which encapsulation of the catalyst species into the formed insoluble siloxane resins contributes to the separation of both metallic and siloxane residues from the product.