We have developed an in vitro culture system composed of organotypic human skin explants interfaced with titanium rods or stainless steel fixator pins. The use of this interface provides a model to evaluate strategies for creating a stable, long-term connection with living skin and chronic percutaneous devices. Our hypothesis is that the delivery of specific biomaterials at this interface will create a dynamic, slowly flowing matrix for skin biointegration, local administration of drugs or antimicrobials. We define this concept as the generation of an artificial mucosa, because it mimics the situation of several epithelial tissues (like the periodontal junction between the tooth and the junctional epithelium) where antimicrobial peptides and mucins are constantly extruded.

To investigate the resistance of actinide host phases to accelerated radiation damage, which simulates radiation induced effects of long term storage, the following samples doped with plutonium-238 (from 2 to 10 wt. %) have been repeatedly studied using XRD and other methods: cubic zirconia, Zr0.79Gd0.14Pu0.07O1.99; monazite, (La,Pu)PO4; ceramic based on Pu-phosphate of monazite structure, PuPO4; ceramic based on zircon, (Zr,Pu)SiO4, and minor phase tetragonal zirconia, (Zr,Pu)O2; single crystal zircon, (Zr,Pu)SiO4; single crystal monazite, (Eu,Pu)PO4; ceramic based on Ti-pyrochlore, (Ca,Gd,Hf,Pu,U)2Ti2O7. No change of phase composition, matrix swelling, or cracking in cubic zirconia were observed after cumulative dose 2.77×1025 alpha decay/m3. The La-monazite remained crystalline at cumulative dose 1.19×1025 alpha decay/m3, although Pu-phosphate of monazite structure became nearly amorphous at relatively low dose 4.2×1024 alpha decay/m3. Zircon has lost crystalline structures under self-irradiation at dose (1.3-1.5)×1025 alpha decay/m3, however, amorphous zircon characterized with high chemical durability. The Ti-pyrochlore after cumulative dose (1.1-1.3)×1025 alpha decay/m3 became amorphous and lost chemical durability. Radiation damage caused crack formation in zircon single crystals but not in the matrix of polycrystalline zircon. Essential swelling and crack formation as a result of radiation damage were observed in ceramics based on Ti-pyrochlore and Pu-phosphate of monazite structure, but not so far in La-monazite doped with 238Pu.

The extremely high scintillation efficiency of lutetium iodide doped by cerium is explained as a result of several factors controlling the energy transfer from the host matrix to activator, two of which are investigated in the present paper. The first one is the increase of the efficiency of energy transfer from self-trapped excitons to cerium ions in the row LuCl3-LuBr3-LuI3. The STE structure and the efficiency of STE to cerium energy transfer are verified by cluster ab initio calculations. We propose and theoretically validate the possibility of a new channel of energy transfer to excitons and directly to cerium, namely the Auger process when Lu 4f hole relaxes to the valence band hole with simultaneous creation of additional exciton or excitation of cerium. This process should be efficient in LuI3, and inefficient in LuCl3. In order to justify this channel we perform calculations of density of states using a periodic plane-wave density functional approach. The performed estimations theoretically justify the high LuI3:Ce3+ scintillator yield.

The electronic current-voltage characteristics of a nanotransistor is studied. The nanotransistor is assumed to consist of a quantum dot active region connected to the source and drain wires and also attached to a gate. The electric current is shown to be influenced by the coupling of electrons to the longitudinal optical phonons, namely, by the up-conversion of the electrons to the higher excited states in a quantum dot, due to a nonadiabatic effect of the lattice vibrations. In the nanotransistor with asymmetric source and drain contacts the up-conversion leads to a spontaneous electric current, or to a spontaneous voltage between the electrodes. We remind existing experiments which might be related to the effect considered.

Indium gallium zinc oxide (IGZO) has attracted recent attention as a high electron mobility amorphous material for high performance thin film transistors and subsequent use in active matrix backplanes for flexible displays. In this study, Eu:IGZO thin films were pulsed laser deposited at room temperature onto sapphire substrates and were investigated by cathodoluminescence and optical transmission. Photoluminescence was not observed with above band gap excitation. Thin film electroluminescent (TFEL) devices were also fabricated from these thin films. The thin films and devices demonstrate characteristic europium emission, with the most intense emission at 611 nm corresponding to the 5D0 to 7F2 transition. Luminescence was observed to increase with increasing oxygen pressure during deposition of the Eu:IGZO thin films and may be related to the free carrier density in the films. The authors believe this to be the first report of an amorphous oxide electroluminescent phosphor.

Temperature dependent Photoluminescence (PL) and Raman spectra have been used to study the defect structure of untreated and thermochemically reduced calcia stabilized zirconia (CaSZ) and yttria stabilized zirconia (YSZ) single crystals. Over the whole temperature range studied the emission (EM) spectrum of the untreated crystals can be decompose into three broad bands, indicating the presence of several radiative electron transitions which can be associated with anion vacancies centers. Results points out to intrinsic F type centers and extrinsic F type centers (FA, FAA) as the main defect generated in the stabilization process. Effect of thermal reduction on the Raman activity caused a decreased in the acoustic mode region and a shift in the maximum of the excitation (EX) spectra. These variations can be related to a broad absorption band centered at ∼365 nm. This is consistent with a nonrandom arrangement of vacancies, which produces the superposition of periodic sequences of vacancies within domains. Concentration of the color centers was determined by optical absorption in the UV-VIS region. PL temperature dependence study in colored samples suggest that no significant new defect was generated in the reduction process, but a recombination of the charges states of the initial intrinsic and extrinsic F centers.

This paper reports the effect of a Pd/Sn catalyst treatment process on the adhesion of electroless copper deposited onto a glass substrate. Adhesion of the copper varied with catalyst treatment time: short or extended catalyst immersion times led to lower adhesion. In this work silanisation of the glass surface with (3-aminopropyl)-trimethoxysilane was used to provide a layer of functional molecules to assist the adhesion of the Pd/Sn catalyst. Surface analysis of the catalyzed glass was carried out by X-ray Photoelectron Spectroscopy (XPS) and together with Time-of-Flight Secondary Ion Mass Spectrometry, showed that the Pd/Sn structures changed with increasing immersion time in the catalyst bath. The Pd XPS core level peaks indicated that Pd(0) became more significant in the catalyst layer than Pd(II) with increasing immersion time. Tape peel testing was used to assess the adhesion of the coatings: thin layers adhered well to the glass, but for layers thicker than 160 nm tape tests removed large areas. The failure surfaces of copper layers peeled off the glass were also examined by XPS which indicated that the failure occurred between the copper and catalyst.

HCM12A is a ferritic-martensitic steel alloy envisioned for cladding and structural material in the Generation IV Supercritical Water Reactor (SCWR). This alloy was oxidized in 600°C supercritical water for 2, 4 and 6 weeks, and the oxide layers formed were analyzed using microbeam synchrotron radiation and electron microscopy. The oxide layers show a three-layer structure with an Fe3O4 outer layer, an inner layer containing a mixture of Fe3O4 and FeCr2O4 and a diffusion layer containing FeCr2O4 and Cr2O3 precipitates along ferrite lath boundaries. The base metal microstructure has a strong influence on the advancement of the oxide layers, due to the segregation at the lath boundaries of chromium rich particles, which are oxidized preferentially.

Non-cementitious grouts have been tested in Olkiluoto for the sealing of fractures with the small hydraulic aperture. A promising non-cementitious inorganic grout material for sealing the fractures of the apertures less than 0.05 mm is commercial colloidal silica called silica sol. The use of colloidal material has to be considered in the long-term safety assessment of a spent nuclear fuel repository. Objective of this work was to determine colloid release from the silica sol gel and stability of silica colloids in different groundwater conditions. To use silica sol as a grout, the injected colloids have to aggregate and form a gel within a predictable time by using a saline solution as an accelerator. Silica sol gel samples were stored in contact with medium salinity and low salinity groundwater simulates. Release of silica colloids and colloid stability was followed by analyzing the colloid concentration, particle size distribution, concentration of reactive silicon, solution pH and zeta potential after one month, half a year and one year. Malvern Zetasizer Nano ZS equipment was used to determine colloidal particle size distributions applying the dynamic light scattering method and zeta potential based on dynamic electrophoretic mobility. The colloidal particle concentration was estimated from Zetasizer measurements applying a standard series. Dissolved reactive silica concentration was determined using the molybdate blue method and total silica concentrations were determined using ICP–MS.The release and stability of silica colloids were found to be dependent significantly on groundwater salinity. Zeta potential values near zero and the increase in particle size at first and then the disappearance of large particles indicated particle flocculation or coagulation and instable colloidal dispersion in a saline groundwater simulate. In low salinity ground water simulate high negative zeta potential values, small particle size and constant size distribution indicate the existence of stable silica colloids. The concentrations of the released colloids were slightly higher than determined in natural granitic ground waters. Under prevailing saline groundwater conditions in Olkiluoto no significant release of colloids from silica sol is expected but the possible influence of low salinity glacial melt waters has to be considered.

This work considers effect of type and content of dopant on the real structure, state of surface Pt species and oxygen mobility of nanocrystalline Lnx(Ce0.5Zr0.5)1-xO2-δ (Ln=La3+, Gd3+, Pr3+/4+) solid solutions prepared by Pechini route. For the reactions of methane selective oxidation and dry reforming into syngas, catalytic activity correlates rather well with either surface (in diluted feeds) or bulk (in realistic feeds) oxygen mobility as well as Pt dispersion controlled by the type and content of a dopant.

Promising nanostructured device concepts with staggering theoretical efficiencies where quantum confined states are embedded in the intrinsic region of conventional p-i-n solar cells have been proposed. However, practical realizations remain inefficient as these devices suffer from an inherent difficulty in the extraction of photo-generated carriers from the confined states. Within the framework of a “single particle in the box” theory, such shortcomings could be addressed by the use of resonant quantum tunneling designs that can expedite carrier escape. Nonetheless, in material systems studied thus far, the implementation of such design becomes elusive as band offsets between the nanostructure and the host material are distributed between the conduction and valence band leading to the confinement of both holes and electrons (i.e. two particle problem). Our studies of such p-i-n Multi-Quantum Well (MQW) solar cells, only differing by their MQW region composition and geometry, have shown a strong dependence of device performance on quantum wells composition and thickness. Leveraging on the special property of dilute nitrides and using a carefully chosen material system and device design we show the possibility of circumventing this problem by separating the optimization of the valence and conduction band and reducing the issue to a single particle problem. Band structure calculations including strain effects, band anti-crossing models and transfer matrix methods are used to theoretically demonstrate optimum conditions for enhanced vertical transport. High electron tunneling escape probability, together with a free movement of quasi-3 D holes, is predicted to result in enhanced PV device performance. Furthermore, the increase in electron effective mass due to the incorporation of N translates in enhanced absorptive properties, ideal for PV application.

Experimental and simulated P and As dopant diffusion profiles in Si:C epi films containing high C (>1 atomic %) are presented. A new set of physical effects were incorporated to accurately model P or As diffusion in the presence of high level of C. Evolution of substitutional C (Csub) profile in the Si:C epi film through dopant implant and activation anneal was characterized by high-resolution x-ray diffraction (HRXRD) technique. Three-layer analysis was utilized to obtain non-uniform Csub profile. Dependency of Csub retention on anneal thermal budget is studied. It is shown the initial Csub in the epi layer is lost during dopant implantation and conventional spike anneal sequence. Use of advanced millisecond (ms) laser anneal resulted in near 100% Csub retention in P-implanted Si:C epi film without compromising junction depth. Measured Csub (by HRXRD) and total C (by SIMS) profiles are compared with the ones predicted by the newly developed compact modeling in this study.

Carbon nanotubes (CNTs) are successfully immobilized on a bamboo charcoal by chemical vapor deposition of gaseous tetraethyl orthosilicate (TEOS). Electron microscopies, Raman spectroscopy and electron energy loss spectroscopy are used to characterize the sample. The CNTs found on the bamboo charcoal support were several microns long, and their diameters ranged from 50nm to 300nm. From the high resolution transmission electron microscopic analysis, we found that the CNTs were composed of ∼30 layers of graphitic carbon sheets. Amorphous droplets were also found at the tips of the CNTs. This suggested that the growth of the CNT was via a vapor-liquid-solid mechanism. The amorphous droplets contained calcium, silicon and oxygen. The calcium impurity was originated from the bamboo while the silicon impurity was supplied by the TEOS. CNTs partially filled with calcium silicate were also found. It was evident that calcium silicate had played a critical role in the formation of these CNTs.

A simple and versatile procedure was developed for synthesizing biomorphic mesoporous Ce1-xZrxO2. Aqueous cerium nitrate and zirconium nitrate solutions, and paper were used as the starting materials. Under the structure-directed effect offered by the active hydroxyl radicals of the cellulose in the paper templates, porous and fibrous structures of paper were replicated by the self-assembly of Ce1-xZrxO2 nanocrystallites after the paper underwent chemical infiltration and calcinations. The product, composing of interwoven network of fibers with diameter ranging from 10 to 20 <mu>m, was a replica of the original paper structure only that each fiber was assembled by Ce1-xZrxO2 nanocrystallites with grain size of 3-10 nm. The templating function of cellulose and the mechanism in the formation of nanocrystallites were proposed.

An aging assessment of the OPG waste resin storage system predicted the potential for premature failure of the carbon steel resin liners. Consequently, resin liners made of 316L stainless steel with a minimum content of 2.5% molybdenum were selected to replace the carbon steel liners. The 2.5% Mo 316L stainless steel was specified to enhance pitting resistance in the spent resin environment. With the additional Mo, one would expect that a brief electrochemical corrosion test will reveal the superiority of such alloy over conventional 316L steel. This study reports a contrary experience

A fiber based lidar system is developed which simplifies the processing of linear FM pulses by using a modulated local oscillator power in the coherent detector. Experiments were conducted on lidar systems with direct, heterodyne and simplified homodyne detection to compare receiver sensitivity. A field experiment using the homodyne system verified the sensitivity estimation on a building target at 370-m range.

Low thermal budget annealing approaches, such as millisecond annealing or solid-phase epitaxy (SPE) of amorphized silicon, electrically activate implanted dopants while minimizing diffusion. However, it is also important to anneal damage to the crystal lattice in order to minimize junction leakage. Annealing experiments were performed on low-energy B implants into both crystalline silicon and into wafers pre-amorphized by Ge implantation. Some wafers also received As implants for halo-style doping, and in some cases the halo implants were pre-annealed at 1050°C before the B-doping. The B-implants were annealed by either SPE at 650°C, spike annealing at 1050°C, or by millisecond annealing with flash-assisted RTP™ (fRTP™) at temperatures between 1250°C and 1350°C. Residual damage was characterized by photoluminescence and non-contact junction leakage current measurements, which permit rapid assessment of damage removal efficacy. Damage from the heavy ions used for the halo and pre-amorphization implants dominates the defect annealing behaviour. The halo doping is the critical factor in determining junction leakage current. Millisecond annealing at high temperatures helps to minimize residual damage while limiting diffusion.

The potential use of carbon nanotubes (CNT) as interconnects requires also new characterization approaches as the existing ones are optimized for three-dimensional materials and do not work for inherently one-dimensional structures like CNTs. Therefore, we have developed a so-called pick-and-place process which allows to remove an individual CNT from a specific site and to place it at another location for further analysis. The approach is based on nanomanipulation combined with scanning electron microscopy (SEM). This paper presents the pick-and-place concept and explains the different steps required for its successful application. We further demonstrate its power by characterizing individual CNTs using transmission electron microscopy (TEM) and atomic force microscopy (AFM). The developed pick-and-place approach overcomes the challenge of site-specific analysis of CNT interconnects and strongly facilitates the routine analysis of CNTs.

We investigated the fabrication of Si nanocrystals, including thin films, by annealing the SiO/C/SiO thin films in an Ar atmosphere. The SiO/C/SiO trilayered thin films were deposited on α-Al2O3 (0001), Si (111), or ITO-coated borosilicate glass substrates at room temperature by pulsed laser deposition using dual sintered SiO and graphite targets. The SiO/C/SiO thin films subjected to heat treatment at 500°C included nanocrystalline Si. Measurements by synchrotron radiation X-ray diffraction indicated the formation of Si nanocrystals having a size of 5–10 nm. Fourier transform infrared spectra showed that Si–O stretching and vibrational peak intensities of the as-deposited thin film decreased remarkably after annealing. The C layer in the SiO/C/SiO trilayered thin films is considered to play a role in enhancing the chemical reaction that produces Si nanocrystals through reduction of SiO during heat treatment. The annealed SiO/C-based thin films, including Si nanocrystals, exhibited photosensitive conduction behavior in current–voltage measurements.