We have shown that hole mobilities of a wide variety of organic thin films can be estimated using a steady-state space-charge-limited current (SCLC) technique due to formation of Ohmic hole injection by introducing a very thin hole-injection layer of molybdenum oxide (MoO3) between an indium tin oxide anode layer and an organic hole-transport layer. Organic hole-transport materials used to estimate hole mobilities are 4,4′,4″-tris(N-3-methylphenyl-N-phenyl-amino)triphenylamine (m-MTDATA), 4,4′,4″-tris(N-2-naphthyl-N-phenyl-amino)triphenylamine (2-TNATA), rubrene, N,N′-di(m-tolyl)-N,N′-diphenylbenzidine (TPD), and N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine (α-NPD). These materials are found to have electric-field-dependent hole mobilities. While field dependence parameters (β) estimated from SCLCs are almost similar to those estimated using a widely used time-of-flight (TOF) technique, zero field SCLC mobilities (μ0) are about one order of magnitude lower than zero field TOF mobilities.

MeV-ion beam has long been applied to biology research and applications for many decades as highly energetic ions are undoubtedly able to interact directly with biology molecules to cause changes in biology. However, low-energy ion beam at tens of keV and even lower has also been found to have significant biological effects on living materials. The finding has led to applications of ion-beam induced mutation and gene transfer. From the theoretical point of view, the low-energy ion beam effects on biology are difficult to understand since the ion range is so short that the ions can hardly directly interact with the key biological molecules for the changes. This talk introduces interesting aspects of low-energy ion beam biology, including basis of ion beam biotechnology and recent developments achieved in Chiang Mai University in relevant applications such as mutation and gene transfer and investigations on mechanisms involved in the low-energy ion interaction with biological matter such as eV-keV ion beam bombardments of naked DNA and the cell envelopes.

The photoluminescence (PL) and photoluminescence temperature dependences have been studied in InAs quantum dots (QDs) embedded in the In0.15Ga1–0.15As/GaAs quantum wells (QWs) with QDs grown at different temperatures (470–535 °C). Ground state (GS) related QD PL peaks shift into the red side with increasing QD growth temperature to 510 °C and the blue shift is observed when the temperature increased to 535 °C. The temperature dependences of GS PL peak positions were fitted on the base of Varshni relation and the fitting parameters were compared with the bulk InAs and the In0.21Ga0.79As allow. This comparison has revealed that for QDs grown at 490–510 °C the PL fitting parameters are the same as for the bulk InAs crystal. The DWELL structures with QDs grown at other temperatures have fitting parameters different from the bulk InAs. Last fact testifies that in these structures the Ga/In inter-diffusion between QDs and a QW has been realized. This Ga/In intermixture can be stimulated not only by the high temperature (535 °C), but by the essential elastic stress as well in the DWELL structure with lower QD densities.

Diatoms are unicellular, photosynthetic microalgae that live in marine and freshwater environments. The cell walls of diatoms are composed of biosilica and have exceedingly hierarchical ornate nanostructures. Consequently, these nanostructures have long been regarded as the paradigm for future silica nanotechnology. We have coated diatom Pinnularia sp. biosilica with a thin film of CdS using a chemical bath deposition technique. Possible uses for these CdS coated diatoms include the development of new nanodevice fabrication techniques and optoelectronic applications. Electron microscopy techniques were utilized to study their morphologies. Their electrical characteristics were investigated using an Agilent 4156C precision semiconductor parameter analyzer and a Cascade probe station. The CdS coating was found to be dense, adherent and nanostructured. The diatoms coated with CdS exhibited both metallic and semiconductor diode behavior.

The reserved cast austenitic stainless steels (CASS) for primary circuit piping in Daya Bay Nuclear Power Plant were studied. The changes of microstructure, mechanical properties and fracture behavior were investigated using SEM, EPMA, TEM and nanoindentation after accelerated aging at 400°C for up to 10000 h. Microhardness of ferrite increased rapidly in the early stage and then increased slowly later. The impact energy of materials declined with the aging time and reduced to a very low level after aging for 10000 hours. Fracture morphology displayed a mixture of cleavage in ferrite along with dimple and tearing in austenite. Two kinds of precipitations were observed in ferrite by TEM after long periods of aging. The fine Cr-enriched α′ phases precipitated homogeneously in ferrite, and a few larger G phases were observed as well. The precipitation of α′ phases was considered to be the primary mechanism of thermal aging embrittlement in CASS.

It is mostly important to develop the fabrication technology of the dielectric thin film with high insulation performance and surface flatness by large-area printing process. We have developed a technique to fabricate a silicon dioxide (SiO2) dielectric thin film by the low temperature solution process. The thin film prepared by about 170°C showed excellent dielectric performance with high resistivity in the order of 10 to the 16 Ωcm and surface flatness with the same degree of thermal oxidized SiO2 thin film on the silicon wafer (RMS=0.15nm). In addition, it is showed that the production of thick film of SiO2 with high dielectric performance and surface flatness is possible by applying over-coating technique. These indicate that this SiO2 production technique is greatly useful for the large-area printed electronics technology.

Colloidal Europium-doped In2O3 nanocrystals were successfully prepared in a noncoordinating solvent using indium (III) and europium (III) acetates as precursors. The concentration of doped europium was varied up to 2.88 at%. Linear electrogyration induced by coherent circularly-polarized light was observed from samples in which europium-doped In2O3 nanocrystals were embedded in photopolymer oligoethracryalte matrices. The result on ˜2.5 at% europium-doped sample shows that the maximal linear electrogyration could reach to ˜12 deg./mm at an electric field of 120V/cm for He-Ne laser.

Vanadium dioxide (VO2) single crystals undergo a structural first-order metal to insulator phase transition at approximately 68°C. This phase transition exhibits a resistivity change of up to 5 orders of magnitude in bulk specimens. We observe a 2-3 order of magnitude change in thin films of VO2. Individual particles with sizes ranging from 50 to 250 nm were studied by means of Transmission Electron Microscopy (TEM). The structural transition for individual particles was observed as a function of temperature. Furthermore, the interface between grains was also studied. We present our current progress in understanding this phase transition for polycrystalline thin films of VO2 from the view of individual particles.

Dry film resist has been used in the fabrication of Masters in microfluidic devices for droplet generation. The minimum feature size in the resist was controlled by the type of mask (transparency or electron beam Cr mask), the resolution of the pattern in transparency masks (2400 or 5080 dpi) and thickness of resist in the range from 35 to 140 μm. The Master patterns formed in dry resist were replicated as a Ni shim and then hot embossed into Plexiglas 99524. These devices were used to generate water-in-oil droplets with a well defined dependence of diameter and frequency on flow parameters. The application of dry laminar resist and transparency masks has allowed the rapid fabrication of prototype devices.

Two important issues in Performance Assessment exercises regarding the alteration of Spent Nuclear Fuel (SNF) are the contribution of Instant or better called Fast release Fraction (FRF) and the effect of High Burn-Up Structure (HBS). Therefore this paper focuses on the effect of HBS in FRF of a PWR irradiated in a commercial reactor with a mean Burn-Up (BU) of 48 GWd/tU. Additionally, determined FRF are compared with previous experiments performed with PWR with a mean BU of 60 GWd/tU, in order to evaluate the effect of BU on FRF.

In order to study the HBS contribution, static leaching experiments are performed with two samples prepared from different radial positions, labeled Core, central region and Out, enriched with HBS. Two synthetic leaching solutions, bicarbonate and bentonitic granitic groundwater are used under oxic conditions.

The estimated FRF are calculated from the determined Fraction of Inventory in Aqueous Phase (FIAP) taking into account the inventory determined experimentally for each fraction.

Higher release is observed for Core sample, which can be an indicative that HBS does not increase the RN release. With the exception of Rb and Cs, which release is higher at lower BU, no clear effect of BU is observed within the studied range.

Worldwide attention has now focused on bioethanol production to combat global warming and to safeguard global energy. Lignocelluloses are expected to be utilized in future as fuel ethanol production because of competition between food and fuel production. One of the major problems in producing ethanol from lignocellulosic biomass is high production cost and consolidated bioprocessing (CBP) is gaining recognition as a potential breakthrough for low-cost biomass processing. Basidiomycetes appear suitable for use in CBP because they can achieve the both events of lignocellulose breakdown and ethanol fermentation. We are developing CBP bioethanol production by using Flammulina velutipes from sorghums. It turns out the relationship between varietal characteristics of sorghums and ethanol conversion properties of F. velutipes, and the direction should be performed in the future became clear.

Brazing process is a cost effective technique to repair wide gap cracks in turbine components made from difficult to weld nickel base superalloys. In this process boron and silicon are used as melting point depressants, however, form hard and brittle intermetallic compounds with nickel (eutectic phases) which are detrimental to the mechanical properties of brazed joints. In this paper the effect of brazing parameters such as temperature and time on final microstructure of brazed joint of nickel base superalloy Inconel 738 using a commercial filler metal alloy (Ni-11Cr-3.5Si-2.25B-3.5Fe) was investigated. The microstructure of the joint layer was characterized by optical and scanning electron microscopy; chemical composition was carried out by energy dispersive X-ray spectrometry (EDS) microanalysis and microhardness testing. The results showed that the formation of eutectic microconstituents, within the joint regions, was significantly influenced by the brazing parameters and gap size, also that formation of eutectic constituents decreased by allowing a sufficient amount of time for a complete isothermal solidification to take place at the brazing temperature.

Effects of hot band annealing on the final microstructure and magnetic properties of cold rolled and annealed non-oriented grain Si-Al electrical steel strips are investigated. Microstructures are characterized using optical and scanning electron microscopy and magnetic properties are determined using a vibrating sample magnetometer. It is shown that annealing of hot rolled bands at temperatures between 800 and 850 °C causes rapid decarburization and development of a microstructure consisting of large columnar ferrite grains free of secondary particles. This microstructure leads, after cold rolling and a fast annealing treatment, to large grain microstructures similar to those observed in production scale, fully processed strips. It is observed that the final grain size increases with the final annealing temperature, leading to a significant improvement of the magnetic properties. Therefore, hot band annealing technology can be an attractive alternative processing route for the manufacture of non-oriented grain low carbon Si-Al processed electrical steel strips.

Direct electrochemical reduction of porous SiO2 pellets in molten CaCl2 salt and CaCl2-NaCl salt mixture were investigated by applying 2.8 V potential. The study focused on the effects of temperature, powder size and cathode contacting materials. Starting materials and electrolysis products were characterized by X-ray diffraction analysis and scanning electron microscopy. Due to reactive nature of silicon, different cathode contacting materials were used to test the extent of reactions between silicon produced at the cathode and the contacting materials. X-ray diffraction patterns showed that silicon produced at the cathode reacted with nickel, and iron in stainless steel to form Ni-Si and Fe-Si compounds respectively. Besides, studies revealed that higher temperature and smaller particle size had positive effects in increasing reduction rate. The results were interpreted from variation of current versus time graphs under different conditions, microstructures and compositions of the reduced pellets.

In this report we present a brief overview of the growth of nanostructures by the oblique angle deposition where the nanostructures possess both out-of-plane and in-plane preferred orientations or a biaxial texture. The degree of preferred crystal orientations can be quantitatively determined from a method called “RHEED surface pole figure analysis” that we developed recently.

While the low thermal conductivities of silica aerogels have made them of interest to the aerospace community as lightweight thermal insulation, the application of conformal polymer coatings to these gels increases their strength significantly, making them potentially useful as structural materials as well. In this work we perform multiscale computer simulations to investigate the tensile and compressive strain behavior of silica and polymer-coated silica aerogels.Aerogels are made up of clusters of interconnected particles of amorphous silica of less than bulk density. We simulate gel nanostructure using a Diffusion Limited Cluster Aggregation (DLCA) procedure, which produces aggregates that exhibit fractal dimensions similar to those observed in real aerogels. We have previously found that model gels obtained via DLCA exhibited stress-strain curves characteristic of the experimentally observed brittle failure. However, the strain energetics near the expected point of failure were not consistent with such failure. This shortcoming may be due to the fact that the DLCA process produces model gels that are lacking in closed-loop substructures, compared with real gels. Our model gels therefore contain an excess of dangling strands, which tend to unravel under tensile strain, producing non-brittle failure. To address this problem, we have incorporated a modification to the DLCA algorithm that specifically produces closed loops in the model gels.We obtain the strain energetics of interparticle connections via atomistic molecular statics, and abstract the collective energy of the atomic bonds into a Morse potential scaled to describe gel particle interactions. Polymer coatings are similarly described.We apply repeated small uniaxial strains to DLCA clusters, and allow relaxation of the center eighty percent of the cluster between strains. The simulations produce energetics and stress-strain curves for looped and nonlooped clusters, for a variety of densities and interaction parameters.

Metallic nanoporous architecture can be spontaneously attained by dealloying of a binary alloy. The nanoporous architecture can be often fabricated in noble metals such as Au and Pt. In this study, nanoporous Ni, Ni-Cu are fabricated by dealloying rolled Ni-Mn and Cu-Ni-Mn alloys, respectively. Unlike conventional Raney nickel composed of brittle Ni-Al or Cu-Al intermetallic compounds, the initial alloys had good workability probably because of their fcc crystal structures. After the electrolysis of the alloys in (NH4)2SO4 aqueous solution, nanoporous architectures of Ni and Ni-Cu with pore and ligament sizes of 10–20 nm were confirmed by scanning electron microscopy and transmission electron microscopy. X-ray diffraction analyses suggested that Ni and Cu atoms form a homogeneous solid solution in the Ni-Cu nanoporous architecture. The ligament sizes of nanoporous Ni and Ni-Cu were smaller than that of nanoporous Cu, reflecting the difference between diffusivities of Ni and Cu at solid/electrolyte interface. Ni can reduce the pore and ligament sizes of resulting nanoporous architecture when added to initial Cu-Mn alloys.

A new multiferroic composite ceramics with the general formula (x)Ba(Sr)Fe12O19-(1-x)BaTiO3 (x=0.1, 0.5) was synthesized via a simple solid-state reaction technique. Crystal structure analysis performed for both materials revealed the presence of two crystalline phases pertinent to the initial composite components. X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to testify the crystallinity, microstructure, and local magnetoelectric interactions between ferroelectric and ferromagnetic grains. Magnetic measurements revealed that the saturation magnetization is proportional to the volume fraction of ferrite phase. Dielectric studies demonstrated strong frequency relaxation due to space charge polarization and high conductivity loss making macroscopic magnetoelectric measurements difficult. Novel nanoscale magnetoelectric effect observed by AFM is discussed.

Magnetic entropy change and refrigerant capacity have been determined for a field change of 20 kOe around the second-order magnetic transition of austenite in as-quenched Ni51.1Mn31.2In17.7 alloy ribbons produced by melt spinning technique. Samples crystallize in a single-phase austenite with the highly ordered L21-type crystal structure and a Curie temperature of 275 K. The material shows a maximum magnetic entropy change of ΔSM max= - 1.7 Jkg-1K-1, an useful working temperature range of 78 K (δTFWHM) and a refrigerant capacity of RC=132 Jkg-1 (RC= │ΔSM max│ x δTFWHM). The considerable RC value obtained together with the fabrication via a single-step process make austenitic Ni-Mn-In ribbons of potential interest as magnetic refrigerants for room temperature magnetic refrigeration.

The aim of the present work is to understand the effect of different parameters such as the molar ratio of metallic ions to fuel in sol-gel solution, pH of the solution, and calcining temperature on the efficiency of the combustion synthesis technique in preparing submicron lanthanum nickel ferrite using metal nitrate-citrate/glycine mixtures. Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) was used to evaluate the powder morphology and elemental composition. The crystal structure of the calcined powders was evaluated by X-ray diffraction (XRD) and the thermal characteristics of the LNF precursors were examined by thermo-gravimetric analysis (TGA) in air, to identify suitable processing conditions. It was found that by increasing the molar ratio of fuel to metallic ions in the precursor solution, calcining could take place at lower temperatures. However, by increasing the molar ratio of fuel to metallic ions, the yield of the combustion process was decreased. Furthermore, the pH value of the precursor solution did not have any influence on the process efficiency over the range examined.