Nickel nanoparticles generated by pulsed laser ablation in liquid CO2

Research on Chemical Intermediates - Nickel nanoparticles with various structures were synthesized by a pulsed laser ablation process in liquid CO2 at 17 °C and 5.2 MPa. A...     

Highly Selective 1,4‐ and 1,6‐Addition of P(O)?H Compounds to p‐Quinones: A Divergent Method for the Synthesis of C‐ and O‐Phosphoryl Hydroquinone Derivatives

The reaction of P(O)? H compounds with p‐quinones could proceed through either 1,4‐ or 1,6‐addition pathways by employing different additives to selectively give the corresponding C‐ and O‐phosphoryl hydroquinone derivatives in good yields. Oxidative double 1,4‐addition of P(O)? H compounds to p‐quinones was also achieved by tuning the solvent, affording a facile synthesis of bis‐substituted hydroquinones with phosphorus functionality. Further studies on these reactions by using optically active H‐phosphinates showed that all addition reactions took place stereospecifically with retention of configuration at the phosphorus center. The findings lead to the establishment of a divergent method for the synthesis of C‐ and O‐phosphoryl hydroquinone derivatives from easily available P(O)? H compounds.     

Temperature‐Directed Micellar Morphological Transformation Using CABC‐Block Copolymers and Its Applications in Encapsulation and Hidden Segment

A temperature‐directed micellar morphological transformation was developed using CABC multi‐block copolymers with a hydrophobic block A, a hydrophilic block B, and a thermally responsive block C with a lower critical solution temperature (LCST). The micellar structure was switched from a star (below LCST) to a flower (above LCST). The transition temperature was tunable in a wide range (11–90 °C) by varying the C monomer composition. The large difference in the loading capacity between the star and flower enabled efficient encapsulation and controlled release of external molecules. Unlike conventional systems, the present star‐to‐flower transformation keeps micellar structures and hence does not liberate polymers but only external molecules selectively. Another application is a hidden functional segment. A functional segment is hidden (shielded) below the LCST and exposed to interact with external molecules or surfaces above the LCST.     

Nonthermal Atmospheric Pressure Plasma for Methylene Blue Dye Decolorization by Using Slug Flow Reactor System

Plasma Chemistry and Plasma Processing - Non-equilibrium pulsed discharge plasma using a gas–liquid slug flow in a glass column as a plasma reactor is developed and applied to methylene blue...     

SiOx films prepared using RF magnetron sputtering with a SiO target

In this study, SiO_x thin films were prepared using reactive radio frequency magnetron sputtering at room temperature with a SiO sintered target. The obtained SiO_x films were identified using X-ray diffraction, transmission electron microscopy, infrared absorption spectroscopy, X-ray photoelectron spectroscopy and ultraviolet-visible transmittance measurement. The x in SiO_x film was controlled from 0.98 to 1.70 by changing the oxygen flow ratio at deposition. Increasing the oxygen flow ratio increased the optical gap of the SiO_x films from 3.7 to greater than 6 eV.     

Nitride‐based hetero‐field‐effect‐transistor‐type photosensors with extremely high photosensitivity

AlGaN/GaN hetero‐field‐effect‐transistor‐type (HFET‐type) photosensors are fabricated with a p‐GaInN optical gate for the detection of visible light. These photosensors employ a two‐dimensional electron gas at the heterointerface between AlGaN and GaN as a highly conductive channel with a high electron mobility. By changing the InN molar fraction in the p‐GaInN optical gate, the wavelength range of the photosensitivity of the HFET‐type photosensors can be controlled. The photosensitivity of the AlGaN/GaN HFET‐type photosensors with a p‐GaInN optical gate greatly surpassed those of commercially available Si pin and Si avalanche photodiodes, and was comparable to those of photomultiplier tubes. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The design of a radio frequency quadrupole LINAC for the RIB project at VECC Kolkata

A radio frequency quadrupole LINAC has been designed for the VECC-RIB project for an input beam energy of 1.0 keV/u and q/A≥1/16. The output energy will be about 90 keV/u for a 3.4 m long, 35 MHz structure. A half-scale cold model of the RFQ has been fabricated and tested for rf structure design study. The beam dynamics and rf-structure design along with the results of the cold model tests will be presented.     

Effects of counter cations of base catalysts on nitrosation mechanisms.

Reaction of 2-butanone (1) with tert-butyl nitrite (tert-BuONO) was performed using base catalysts (RO-M+: R=CH3, C2H5; M+=Li+, Na+, K+) in alcohols (CH3OH or C2H5OH). In this report, the effects of M+ of RO-M+ on the nitrosation mechanisms were investigated. The yield of E-hydroxyimino compound (5E) increases much better in the reaction using Na+ or K+ as M+ compared with that using Li+. It is also observed that the yield of 5E increases by addition of crown ether as a cation-capturing agent. The experimental results suggested that under the conditions lowering the effects of M+ of RO-M+ on the nitrosation mechanisms, because the reactivity of naked enolate of I increases and the reaction in the C-N bond formation process tends to proceed via open-chain transition state without M+, the yield of 5E tends to increase.     

Development of a nuclear spin polarizer with the optical pumping method

We have developed an optical pumping NMR system for semiconductors as an effective nuclear spin polarizer for a solid-state NMR quantum computer. The system was successfully applied to enhance ³¹P nuclear spin polarization in InP doped with Fe, and the enhancement of the ³¹P NMR signal by more than two orders of magnitude was achieved. We also observed the strong dependences of the enhancement on the helicity and the photon energy of incident light. The most effective enhancement was achieved with the helicity σ⁺ and photon energy smaller than the bandgap by 1015 meV.