Functionalized Self‐Assembled InAs/GaAs Quantum‐Dot Structures Hybridized with Organic Molecules

Low‐dimensional III–V semiconductors have many advantages over other semiconductors; however, they are not particularly stable under physiological conditions. Hybridizing biocompatible organic molecules with advanced optical and electronic semiconductor devices based on quantum dots (QDs) and quantum wires could provide an efficient solution to realize stress‐free and nontoxic interfaces to attach larger functional biomolecules. Monitoring the modifications of the optical properties of the hybrid molecule–QD systems by grafting various types of air‐stable diazonium salts onto the QD structures surfaces provides a direct approach to prove the above concepts. The InAs/GaAs QD structures used in this work consist of a layer of surface InAs QDs and a layer of buried InAs QDs embedded in a wider‐bandgap GaAs matrix. An enhancement in photoluminescence intensity by a factor of 3.3 from the buried QDs is achieved owing to the efficient elimination of the dangling bonds on the surface of the structures and to the decrease in non‐radiative recombination caused by their surface states. Furthermore, a narrow photoluminescence band peaking at 1620 nm with a linewidth of 49 meV corresponding to the eigenstates interband transition of the surface InAs QDs is for the first time clearly observed at room temperature, which is something that has rarely been achieved without the use of such engineered surfaces. The experimental results demonstrate that the hybrid molecule–QD systems possess a high stability, and both the surface and buried QDs are very sensitive to changes in their surficial conditions, indicating that they are excellent candidates as basic sensing elements for novel biosensor applications.     

Development of three-dimensional reactor analysis code system for accelerator-driven system,ADS3D and its application with subcriticality adjustment mechanism

In order to perform the parametric survey for an accelerator-driven system (ADS) core with the subcriticality adjustment mechanism, a new calculation code system, ADS3D, was developed on MARBLE which is a comprehensive and versatile framework for reactor analysis. The application of ADS3D was also demonstrated on the neutronics design of ADS operated by control rod (CR) movement. Through the neutronics calculation, it was shown that the maximum proton beam current was decreased from 20.5 to 11.6 mA due to the switch from beam-operated to CR-operated core.     

Examination of degradation mechanism due to negative bias temperature stress from a perspective of hole energy for accurate lifetime prediction

An evaluation method using the modified hole injection method is proposed to evaluate Negative Bias Temperature Instability (NBTI) in this paper. The physical backgrounds of the evaluation method are strictly discussed. The proposed method accelerates the degradation such as the threshold voltage (V_th) shift by the amount of the hole injection without the high gate voltage stress. Our experimental and theoretical frameworks clarify that two degradation mechanisms, one follows the reaction–diffusion (R–D) model and another follows the hole trap/de-trap (HTD) model, coexist in NBTI. In the inversion layer, holes distributed in the quantized upper energy levels especially induce the degradation that follows the R–D model, and holes distributed in the ground energy level induce the degradation that follows the HTD model. Finally, the accurate NBTI lifetime prediction is demonstrated using the proposed acceleration method.     

Influence of short distance sequence regularity on preparation of poly(p-oxybenzoyl-co-p-mercaptobenzoyl) whisker

Preparation of the poly(p-oxybenzoyl-co-p-mercaptobenzoyl) whiskers was examined by means of the crystallization of oligomers during solution polymerization. Polymerizations were carried out in liquid paraffin at the concentration of 1.0% and 300 °C for 6 h. Copolymerization of 4-acetoxybenzoic acid and S-acetyl-4-mercaptobenzoic acid did not yield the whiskers. This was attributed to tendency that the copolymerization reduced the crystallizability of oligomers and induced the liquid-liquid phase separation of oligomers due to the lower freezing point. In order to induce short distance sequence regularity into oligomers, copolymerizations of two among four monomers were conducted, which were 4-(4-acetoxybenzoyl)oxybenzoic acid, S-(4-acetoxybenzoyl)-4-mercaptobenzoic acid, 4-(S-acetyl-4-mercaptobenzoyl)oxybenzoic acid and S-(S-acetyl-4-mercaptobenzoyl)-4-mercaptobenzoic acid. The copolymerizations of two of these monomers yielded the whiskers but for that of 4-(4-acetoxybenzoyl)oxybenzoic acid and S-(S-acetyl-4-mercaptobenzoyl)-4-mercaptobenzoic acid. The short distance sequence regularity of oligomers brought about the crystallization of oligomers, leading to the formation of whiskers.     

Role of ADS in the back-end of the fuel cycle strategies and associated design activities: The case of Japan

Reduction of burden caused by radioactive waste management is one of the most critical issues for the sustainable utilization of nuclear power. The Partitioning and Transmutation (P&T) technology provides the possibility to reduce the amount of the radiotoxic inventory of the high-level radioactive waste (HLW) dramatically and to extend the repository capacity. The accelerator-driven system (ADS) is regarded as a powerful tool to effectively transmute minor actinides (MAs) in the “double-strata” fuel cycle strategy. The ADS has a potential to flexibly manage MA in the transient phase from light water reactors (LWRs) to fast breeder reactors (FBRs), and can co-exist with FBR symbiotically and complementarily to enhance the reliability and the safety of the commercial FBR cycle. The concept of ADS in JAEA is a lead-bismuth eutectic (LBE) cooled, tank-type subcritical reactor with the power of 800 MWth driven by a 30 MW superconducting LINAC. By such an ADS, 250 kg of MA can be transmuted annually, which corresponds to the amount of MA produced in 10 units of LWR with 1 GWe. The design study was performed mainly for the subcritical reactor and the spallation target with a beam window. In Japan, Atomic Energy Commission (AEC) has implemented the check and review (C&R) on P&T technology from 2008 to 2009. In the C&R, the benefit of P&T technology, the current status of the R&D, and the way forward to promote it were discussed.     

Characterisation of gelatin–fatty acid emulsion films based on blue shark (Prionace glauca) skin gelatin

Incorporation of fatty acids (stearic and oleic) into edible films based on blue shark (Prionace glauca) skin gelatin was investigated to modify properties such as water vapour barrier and flexibility due to their hydrophobicity and plasticizing effect, respectively. Addition of stearic acid from 0% to 100% of protein concentration in the film-forming solution considerably decreased water vapour permeability of gelatin–fatty acid emulsion films compared to addition of oleic acid at the same fatty acid concentration. Increasing concentrations of both fatty acids decreased tensile strength, but increased elongation at break due to their plasticizing effect. At the same concentration, oleic acid gave a greater plasticizing effect than did stearic acid. On the other hand, transparency of the gelatin–stearic acid emulsion film was lower than that of the gelatin–oleic acid emulsion film. Faster stirring speed of homogenisation improved properties of only the gelatin–stearic acid emulsion film.     

Electron‐beam‐pumped light sources using graphite nanoneedle field emitters and Si electron‐transparent films

Sputter‐induced carbon nanoneedle field emitters and Si electron‐transparent films have been developed for electron‐beam‐pumped light sources. The sputter‐induced carbon nanoneedle field emitters exhibited a stable electron emission of 0.1 mA at an average field of 13 V/µm. The 1.5‐µm thick Si electron‐transparent films achieved an electron transmittance of about 60% at an acceleration voltage of 27 kV. An electron‐beam‐pumped light source was demonstrated from the excitation of N₂ gas, and a N₂ gas spectrum was clearly observed. The increase of the beam current is important for increasing the light intensity. Copyright © 2007 Institute of Electrical Engineers of Japan© 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Primary pulmonary artery sarcoma

1. The aim of the present study was to evaluate the effect of grapefruit juice on urinary 6 beta-hydroxycortisol and cortisol excretion in healthy subjects. 2. The ratio of 6 beta-hydroxycortisol/cortisol was significantly decreased (P = 0.036) in the 0-4 h fraction of urine after ingestion of grapefruit juice, but not in the 4-24 h fraction (P = 0.218) or for the compiled data, fraction 0-24 h (P = 0.114). 3. These results indicate that endogenous cortisol metabolism may not only be of hepatic origin, but may also be dependent on the metabolic capacity of cytochrome P450 IIIA (CYP3A) in the gut mucosa. 4. This finding may cast further doubts of the usefulness of the 6 beta-hydroxycortisol/cortisol ratio as an indicator of hepatic CYP3A activity.