In this work, we report a comparative investigation of InxGa1-xN (SL) and InxGa1-xN/GaN (MQW) structures with an indium content equivalent to x=10%. Both structures are grown on (0001) sapphire substrates using MOCVD and MBE growth techniques. Optical properties are evaluated for samples using PL characteristics. Critical differences between the resulting epitaxy are observed. Microstructures have been assessed in terms of crystalline quality, density of dislocations and surface morphology. We have focused our study towards the fabrication of vertical PIN photodiodes. The technological process has been optimized as a function of the material structure. From the optical and electrical characteristics, this study demonstrates the benefit of InGaN/GaN MQW grown by MOCVD in comparison with MBE for high speed optoelectronic applications.

There are some regions where it is difficult to exclude the possibility of appearance of new volcanic activity on the site even if the geological disposal site is located far from existing volcanos in Japan. In order to identify the influence of volcanic eruption at the site to the public if it occurs, public exposure doses were evaluated based on the two scenarios considering types of eruption at new volcanic activity in Japan. One is the exposure by volcanic ash widespread by Strombolian eruption and deposited on the ground surface, including radionuclides from vitrified waste forms after a volcanic conduit penetrated the repository. The other is that by waste forms appeared at the ground surface by Merapi type pyroclastic flow. Exposure doses of the residents living on the volcanic ash do not exceed 1mSv/y even when the eruption occurs at 1,000 years after closure of disposal site. Exposure dose rate for the volcanic researchers temporarily approaching naked waste forms without realizing radioactive wastes is 0.8mSv/h when the eruption occurs 100,000 years after. It indicated that attention should be paid to the influence by Merapi type pyroclastic flow on researchers approaching waste forms appeared rather than that by Strombolian eruption on residents living on the volcanic ash widespread.

Submicron-sized poly(lactide-co-glycolide) nanoparticles (PLGA-NPs) stabilised with bovine serum albumin (BSA) are dual radiolabelled using gamma emitters with different energy spectra incorporated into the core and coating. PLGA core is labelled by encapsulation of 111In-doped iron oxide NPs inside PLGA-NPs during NP preparation, while the BSA coating is labelled by electrophilic substitution using 125I. After intravenous administration into rats, energy-discriminant single-photon emission computerised tomography (SPECT) resolved each radioisotope independently. Imaging revealed different fates for the core and coating, with a fraction of the two radionuclides co-localising in the liver and lungs for long periods of time after administration, suggesting that NPs are stable in these organs. The general methodology reported here represents an excellent alternative for visualising the degradation process of multi-labelled NPs in vivo and can be extended to a wide range of engineered NPs.

Boron Doped Diamond (BDD) electrodes exhibit excellent properties including a wide potential window in aqueous media, high corrosion resistance, chemical inertness, bio-compatibility and low background current. In order to increase their selectivity for analytical applications, several studies were carried out recently on the possibility to deposit metal nanoparticles such as Pt or Ir on such BDD electrodes1,2,3,4. Indeed these nanoparticles bring interesting electro-catalytic properties to the electrodes, thus offering the possibility to address new analytes. Here an electrode array was developed, based on multiple BDD electrodes casted with various metal nanoparticles. The simultaneous detection of analytes by each electrode composing the array gives potentially a unique fingerprint to the analytes, thus increasing the specificity and the selectivity of the sensor.

In the present study, highly sensitive and high-throughput optical waveguide biosensors were fabricated by using the sensing membranes containing dye and polymer-enzyme complex. Optical light waveguide can detect the optical change in the vicinity of the guide surface with high sensitivity due to the evanescent wave scattering. The glucose sensing membranes, composed of dye, enzymes, and biocompatible polymers were prepared by solution processing on the optical waveguide. Herein, we used 3, 3’, 5, 5’-tetramethylbenzidine (TMBZ) as a dye, glucose oxidase (GOD) and peroxidase (POD) as enzymes, phosphatide polymer for protection of biological activity of enzyme, and carboxymethyl cellulose (CMC) as a binder. Then we focused on the optimal composition and structure of sensing membranes for the enhancement in the sensitivity and response speed. The developed glucose sensors demonstrated 20 times higher sensitivity than the conventional light waveguide glucose sensors and the low-detection limit of 0.1g/L glucose within the detection time of 60 sec. For further improvement in the sensitivity, microporous sensing membranes were fabricated by using electrospraying technique. The electroprayed sensing membranes gave 40 % higher sensitivity than nonporous sensing membranes. These results show that both the composition and structure of sensing membrane are crucial factors for highly sensitive and high-throughput optical waveguide biosensors.

Samples of 238Pu-doped single-phase ceramics based on cubic zirconia, Zr0.79Gd0.14Pu0.07O1.93, and monazite, La0.9Pu0.1PO4, have been studied by static leach test in distilled water. Before leach test accumulated doses were (in alpha-decays/m3 x 1026): from 1.6 to 1.7 – for cubic zirconia; and 1.0 – for monazite. Despite high radiation damage both phases remained crystalline according to XRD analysis. The results of static leach tests demonstrate the following Pu normalized mass loss (in g/m2, 90°C, 28 days): from 0.3 to 0.7 – for cubic zirconia; and 1.6 – for monazite. These data are discussed in comparison with results of previous leach tests carried out at lower accumulated doses.

Dimagnesium silicide is an eco-friendly thermoelectric compound whose constituent elements of both Mg and Si are non-toxic and exist in abundance on the earth. In this study, we attempted to control the thermal conductivity of Al-doped Mg2Si by grain refinement. Three types of Si powders, i.e., commercial coarse powder, its pulverized powder and commercial fine powder were prepared for synthesizing the Al-doped Mg2Si. Mg powder and one of the Si powders were weighed with Mg/Si mole ratio of 67/33, and mixed with Al powder with amount of 0.1 at.%. The Al-doped Mg2Si compounds were synthesized using three different Si powders via a liquid-solid phase reaction process under unified synthesizing conditions. A part of the synthesized Mg2Si powder using the coarse Si powder was pulverized. Four kinds of Mg2Si powders were sintered by pulse discharge sintering method under unified sintering conditions. The sintered samples of the synthesized Mg2Si powders made from the fine and the milled Si powders and of the milled Mg2Si powder had the grain-refined microstructure. Especially, the sintered sample of the milled Mg2Si powder was effective for grain refinement and for reduction of thermal conductivity, and had the best thermoelectric performance of ZT = 1.15 at 873 K.

A modified design of the transmission line model test structure uses the simplecalculation of specific contact resistance, ρc, based on atwo contact linear pattern but without the requirement of a mesa etch. Thismodified structure uses a linear TLM with semicircular terminations at each end.The function of the semicircular terminations is to confine the fringing fieldsat the ends of the linear TLM contacts. Simple analytical equations fordetermining ρc have been developed on the basis of themodified linear TLM pattern. These calculations have shown good agreement with afinite element model (FEM) of the modified TLM test structure using typicalparameters for metal/ SiC contacts.

A Kinetic Monte Carlo simulation, using a modified version of the SPPARKS code, of simple defects and complex vacancy clusters was run on a bcc lattice. In this simulation the complexity of void formation was varied by introducing a detachment rate for individual vacancies leaving the void and either treating this value as constant for all size voids or having this value be dependent on the size of the void. Molecular Dynamics simulations were used to determine the binding energies of vacancies for voids of varying size. The simulation was then run over long time periods to determine the number of defects in the simulation under irradiation conditions. It was found that the additional complexity of size dependent void detachment rates had little effect on the defect concentrations and thus a constant barrier should be sufficient for simulations of voids in bcc metals.

We performed first-principles study of electronic properties of FeCrxSe (x=0.0, 0.01, 0.02, 0.04) alloys using the Green’s function-based Korringa-Kohn-Rostoker Atomic Sphere Approximation method within the coherent potential approximation (KKR-ASA-CPA). The KKR-ASA-CPA method is implemented with density function theory (DFT). We find that the excess of Cr into FeSe significantly affects the electronic structure with respect to the parent FeSe. The results have been analyzed in terms of changes in the density of states (DOS), partial DOS, band structures, Fermi surface, bare Sommerfeld constant and the superconducting transition temperature of FeCr0.01Se, FeCr0.02Se and FeCr0.04Se alloys respectively. Our calculations show that calculated Tc for these alloys are close to experimental values, given the nature of approximations used in our calculations.

Membranes for selective water vapor separation were assembled from graphene oxide suspension using techniques compatible with high volume industrial production. The large-diameter graphene oxide flake suspensions were synthesized from graphite materials via relatively efficient chemical oxidation steps with attention paid to maintaining flake size and achieving high graphene oxide concentrations. Graphene oxide membranes produced using scalable casting methods exhibited water vapor flux and water/nitrogen selectivity performance meeting or exceeding that of membranes produced using vacuum-assisted laboratory techniques. (PNNL-SA-117497)

New 1212- type Molybdo-Cuprates of with composition Mo0.5Cu0.5Sr2RECu2O7.5 (RE = Rare Earth) have been prepared by High Pressure and High Temperature (HPHT) synthesis. Their crystal structures are characterized by combining the X-Ray/Neutron powder diffraction and electron diffraction techniques. All the materials show tetragonal symmetry, crystallizing in the P4/mmm space group (S.G.). The chain oxygens are randomly distributed in the two different oxygen sites, which are not completely filled and the defect induced by oxygen vacancies in fact makes the chain fragmented and disordered. The microstructure of these compounds is interpreted by a well-known diagonal cell √2ap × √2ap × 3ap, as confirmed by the Electron diffraction (ED) and transmission electron microscope (TEM). X-ray photoelectron spectroscopy (XPS) studies show the predominance of the non magnetic MoVI state over the MoV one. At the same time oxidation state of copper is found to be dominated by CuII.