Correlation Among the Variant Group,Effective Grain Size,and Elastic Strain Energy During the Phase Transformation in 9Ni Steels

The effect of carbon content on the density of variant-pair boundaries was investigated in 9Ni steel using an electron backscatter diffraction patterns method. The changes in the density of variant-pair boundaries were correlated with the nondestructive measured values of shear modulus of the austenite phase at the phase transformation point. Furthermore, the effective grain size was correlated with the shear modulus and the density of variant-pair boundaries. These relations are discussed from the viewpoint of self-accommodation of elastic strain energy and the nucleation event in the bainite and martensitic transformations.     

Development of the high-energy neutron fluence rate standard field in Japan with a peak energy of 45 MeV using the 7Li(p,n)7Be reaction at TIARA

In this study, we developed a 45 MeV neutron fluence rate standard of Japan. Quasi-monoenergetic neutrons with a peak energy of 45 MeV in the neutron standard field were produced by the ⁷Li(p,n)⁷Be reaction using a 50-MeV proton beam from an azimuthally varying field (AVF) cyclotron of the Takasaki Ion Accelerators for Advanced Radiation Application (TIARA). The neutron energy spectrum was measured using an organic liquid scintillation detector and a ⁶Li-glass scintillation detector by the time-of-flight method, and using a Bonner sphere spectrometer by the unfolding method. The absolute neutron fluence was determined using a proton recoil telescope (PRT) composed of the liquid scintillation detector and a Si(Li) detector that was newly developed in the present study. The detection efficiency of the PRT was obtained using the MCNPX code. The peak neutron production cross section for the ⁷Li(p,n)⁷Be reaction was also derived from the neutron fluence in order to confirm the neutron fluence of the TIARA high-energy neutron field. The peak neutron production cross section obtained in the present study was in good agreement with those of previous studies. The characteristics of the 45-MeV neutron field in TIARA were successfully evaluated in order to calibrate high-energy neutron detectors and high-energy neutron dosimeters.     

On the sliding and profile of a liquid droplet on a rotating disk

This theoretical and experimental study was conducted to investigate the critical condition at which a liquid droplet starts to move on a rotating disk. The critical rotational speed ω was theoretically calculated based on the force balance between the surface tension and the centrifugal force, where ω was experimentally measured for each combination between three kinds of test plates and test liquids. The movements of droplets were judged from the careful observation of infinitesimal motion of the three‐phase contact line. The calculated rotational speeds agreed well with measured ones for arbitrary contact angle when the droplets were set on the plate. The three‐dimensional surface profiles of droplets were calculated from the approximate Laplace equation in which the contact line was assumed as the combination of two ellipses with different ratio of measure to minor axis. The measured profiles on the rotating disk were approximated well by the method proposed in this study. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20276     

Graphene-like bilayer hexagonal silicon polymorph

We present molecular dynamics simulation evidence for a freezing transition from liquid silicon to quasi-two-dimensional (quasi-2D) bilayer silicon in a slit nanopore. This new quasi-2D polymorph of silicon exhibits a bilayer hexagonal structure in which the covalent coordination number of every silicon atom is four. Quantum molecular dynamics simulations show that the stand-alone bilayer silicon (without the confinement) is still stable at 400 K. Electronic band-structure calculations suggest that the bilayer hexagonal silicon is a quasi-2D semimetal, similar to a graphene monolayer, but with an indirect zero band gap.      

Towards sustained delivery of small molecular drugs using hydroxyapatite microspheres as the vehicle

The aim of this work is to explore the possibilities of using hydroxyapatite microspheres (HAP-MS) and polymer coated HAP-MS as the vehicles for the sustained release of small molecular drugs. The adsorption/desorption behaviors of model drug, doxycycline hydrochloride (Dox·HCl), on HAP-MS were systemically studied. Drug loaded HAP-MS was encapsulated by biodegradable PLGA using S/O/W emulsion–solvent evaporation method, and the in vitro drug release was tested. The adsorption kinetics of Dox·HCl onto HAP-MS fitted well to Freundlich model at lower drug concentrations, but when the HAP-MS was incubated in concentrated drug solutions higher than a critical concentration, precipitation of drug from solutions occurred. Rapid desorption or release of Dox·HCl from HAP-MS was observed. While, the release profile of Dox·HCl from PLGA coated microspheres showed steady slow drug release lasted for at least 7 days without obvious burst release. PLGA coated HAP-MS may provide a novel, injectable carrier for loading and long-period sustained release of small molecular, water-soluble drugs.     

Formation of ZnO nanostructures in energy-controlled hollow-type magnetron RF plasma

In this study, we investigated how zinc, sputtered from a zinc target, reacts with oxygen on the substrate to form ZnO nanostructures when the discharge parameters, such as gas flow ratio and target bias voltage, are controlled in O₂/Ar plasma. The deposits were estimated by SEM and Raman spectroscopy. Under conditions of a Zn to Ar optical emission intensity ratio of 2/1, a target voltage of − 550 V, a total pressure of 40 Pa, a substrate temperature of 150 °C, an RF power of 50 W, and a deposition time of 30 min, many vertically aligned ZnO nanorods were observed to be deposited on the substrate. The diameter of the rods was typically 50 nm. It was found that the film morphology can be controlled by the sputtering rate of zinc varied by the target bias voltage and gas flow rate.     

Self-Alignment of Optical Devices With Fiber for Low-Cost Optical Interconnect Modules

We propose a novel self-alignment process of optical devices with optical fiber. A vertical-cavity surface-emitting laser (VCSEL) was automatically coupled with a multimode fiber (MMF) through the surface tension of a liquid adhesive within 1.5 s. Misalignment between the center of the VCSEL and the fiber was measured to be 15 mum, which is acceptable for coupling the VCSEL with the MMF. High-speed pulse modulation of the self-aligned VCSEL up to 5 Gb/s, as well as at 1 Gb/s, was demonstrated. The average optical output power was as high as -5.9 dBm at 1 Gb/s.     

High optical coupling efficiency using 45 °-ended fibre for low-height and low-cost optical interconnect modules

High optical coupling efficiency of more than 80% between an optical fibre and a vertical-cavity surface-emitting laser (VCSEL) has been achieved without use of a lens. A 45deg-ended fine-drawn optical fibre can be positioned closer to a VCSEL than a conventional multimode fibre. 12.5 Gbit/s/ch optical signal transmissions using a low-height optical coupling structure have been demonstrated with optical output power as high as +2.0 dBm without use of a lens.     

High efficiency production of astaxanthin in an airlift photobioreactor

In photobioreactors, photosynthetic microorganisms are exposed to certain light/dark cycles caused by light intensity distribution and mixing inside the photobioreactor. In this study, Haematococcus pluvialis was cultivated in an airlift and a bubble column photobioreactor, and the cell growth and astaxanthin production were compared to clarify the effects of liquid circulation.