The electrochemical reduction of H2O2 on SIMFUEL was investigated over the pH range 1 to 4. The mechanism at pH 4 is known to occur on UV species incorporated into a surface layer of UIV 1-2xUV 2xO2+x. However, below pH 3, reduction occurs on an adsorbed UVO2(OH) state which is unstable and oxidizes to insulating UVI before dissolving as UO2 2+. Both schemes are observed at intermediate pH’s. The presence of both low and high acidic regions at the electrode surface is determined by the combination of peroxide concentration, bulk pH and the surface diffusion conditions.

The potential of chemically derived graphene as a solution-processable transparent conductive film has been explored. Synthesis of amine-functionalized graphene oxide was intended for its utilization in layer-by-layer assembly. Layer-by-layer assembly of graphene oxide was utilized to fabricate graphene based thin film in a scalable and highly reproducible way. It was found that optical transmittance and sheet resistance of the film decreases with an increase in number of LBL cycles in a reproducible way. The sheet resistance of LBL-assembled GO film improves by an order of magnitude at the same optical transparency due to more homogeneous coverage and better stacking of graphene flakes. Furthermore, we demonstrated the potential for a large-scale deposition of chemically derived graphene.

SiGe nanowires of different Ge atomic fractions up to 15% were grown and ex-situ n-type doped by diffusion from a solid source in contact with the sample. The phenomenon of dielectrophoresis was used to locate single nanowires between pairs of electrodes in order to carry out electrical measurements. The measured resistance of the as-grown nanowires is very high, but it decreases more than three orders of magnitude upon doping, indicating that the doping procedure used has been effective.

Potassium (K) ions have been implanted in hydrothermally grown ZnO to a dose of 1 × 1015 cm-2, followed by isochronal annealing in a tube furnace (30min) and by rapid thermal annealing (30s) on two separate samples. For annealing temperatures below 700°C, only a minor redistribution of Li is observed behind the projected range of the K+ ions. At temperatures between 700 and 750°C, however, both annealing treatments show a wide region behind the implantation peak which is depleted of Li, and this depletion is used as a tracer to monitor diffusion of intrinsic defects like the Zn interstitial. The results are interpreted as Zn interstitials being released from the implanted region in a burst at temperatures above ∼700°C, followed by rapid migration, replacement of Li on Zn site through the kick-out mechanism, and migration of Li away from the active region.

At present, the industrial sector requires the recovery of tool steel componentssubjected to severe wear which are built with steel HWS these have the sameproperties in all tribology directions and have great success in buildingtooling. In this paper, we recover the previously HWS steel machining with afillet of 2mm caused by the metallurgical recovery of the component, applyingthe process of plasma transferred arc PTA which has very good fats dilutionproperties in comparison to other conventional processes currently applied forthe recovery of tooling, such as GTAW, SMAW, SAW. The experiment was conductedwith input D2 and M2 with one and two welding seams, making the assessmentmetallography, hardness and wear tests pin-on-disk. Finding a decrease in thehardness of the interface line, according to the evaluation of wear pin-on-disk,had a higher wear rate of the filler metal in the M2 D2.

Differentiated neurons (dorsal root ganglia and cortical neurons) have been shown to develop longer neurite extensions on softer materials than stiffer ones, but previous studies do not address the ability of neural stem cells to undergo differentiation as a result of material elasticity. In this study, we investigate neuronal differentiation of C17.2 neural stem cells due to growth on polyacrylamide gels of variable elastic moduli. Neurite growth, synapse formation, and mode of division (asymmetric vs. symmetric) were all assessed to characterize differentiation. C17.2 neural stem cells were seeded onto polyacrylamide gels coated with Type I collagen. The cells were then serum starved over a 14 day period, fixed, and analyzed for biochemical markers of differentiation. For division studies, time-lapse imaging of cells on various substrates was performed during serum withdrawal using the Nikon Biostation. Division events were analyzed using ImageJ to quantify sizes of resulting daughter. Data shows that C17.2 cell differentiation (as dictated by number and type of division events) is dependent upon substrate stiffness, with softer polyacrylamide surfaces (140 Pa) leading to increased populations of neurons and increased neurite length. Our data also indicates that the ability of neural stem cells to express synaptic proteins and develop synapses is dependent upon material elasticity.

Inkjet printing of alternate layers of anionic and cationic polyelectrolytesallows organized gels to form with structures similar to those made bylayer--by-layer dipping methods but very much faster. Structures of gelsformed using slow and fast inkjet printing systems are compared usingelemental analysis, swelling and diffusion kinetics as characterizationmethods. After printing and washing, most sodium or chloride counter-ionsare last from the gel, leave only the polymer complex. The swellingproperties of the printed and washed gel depend on the deposition rate andon the ratio of the two polymers as originally printed. The syntheticpolyelectrolytes reported here can be compared with biologicalpolyelectrolytes reported earlier by us.

Research reactors spent fuels disposal is a problematic area that conduces to the quest of feasible solutions for ensure safe destination of the spent fuels. In this work, a new method for processing spent fuel from MTR reactors is presenting. The main objective of this process, is the immobilization of principal radioactive elements that are present in the spent fuel, in order to achieve a suitable material which could be temporally stored safely. The Vitrocerus method involves ordinary physical procedures performed in a hot cell. It differs from conventional vitrification because there is a reduction in volume of glass material added.

The process propose the ceramization of a mixture of spent fuel plates (wich were milled and calcined previously) with natural uranium oxide (U3O8) to obtain the desired isotopic dilution (to low the U235 enrichment). At the same time, a small fraction of VG98/12 glass [1] was added to enhance low temperature sintering. The treatment and conditioning tasks proposed in Vitrocerus were tested on MTR fuel miniplates that simulate a real U3Si2 dispersed in Al fuel, which were successfully transformed into ceramic sintered pellets [2,3] with low enrichment, structural integrity, outstanding mechanical properties and water corrosion resistance. Eventually these pellets could be stored safely in an interim dry storage facility.

A high molecular weight, photocurable inorganic-organic hybrid based on ladder-like poly(phenyl6-co-methacrylate4)silsesquioxanes (LPPMA64) was investigated as a flexible display substrate. Photocured free standing films with 40μm thickness showed high transparency (>95%), excellent thermal stability (Td >450°C), and low coefficient of thermal expansion (38ppm/K) without the use of reinforced glass fibers. Furthermore, these ladder-like structured materials did not require any thermal treatment processes due to the negligible amounts of uncondensed groups, thus simplifying manufacturing processing. These novel hybrid films present an alternative to organic plastics as flexible electronic device substrates due to their excellent optical and thermal properties.

In this paper, a Particle Swarm Optimization (PSO) algorithm is presented to find the optimal combination of corrosion rate parameters for a refining process in the oil industry. The experimental data in this paper are constituted by results obtained from field tests. Maintenance control is a very important aspect in order to prevent substantial damage to facilities, equipment and people. Other important factor to consider is the cost of maintenance which tends to reduce the required actions. The main parameters in corrosion control are flow, concentration of sulfur species, total acid number (TAN), temperature, and chromium content. However it is not easy to know the combined effect of different variables due to synergistic effects. Particle swarm optimization (PSO) is a population based stochastic optimization technique, inspired by social behavior of bird flocking or fish schooling. The system is initialized with a population of random solutions and searches for optima by updating generations. In PSO, the potential solutions, called particles, fly through the problem space by following the current optimum particles.

Emerging NVM devices have been extensively studied as candidates to extend density scaling and power reduction beyond Si-based flash. Recently, resistive-random-access-memory (ReRAM) devices in the form of metal-insulator-metal (MIM) structures have attracted substantial attention due to their potential scalability, low power operation, and high speed. HfO2 is attractive compared to other transition metal oxides from the vantage point of CMOS process compatibility. Here, we investigate doped HfO2 with a Pt top electrode on an n+-Si substrate. By doping HfO2 with Hf or Au, improved resistive switching properties have been demonstrated in terms of enhanced cycling endurance and lower switching voltages for SET and RESET. The improvements were attributed to doping-induced oxygen vacancies. In addition, Cu-doped HfO2 devices have exhibited multilevel resistive switching.

Inorganic erbium-doped glasses are widely used in telecommunications due to the sharp intra-atomic 4I13/2 → 4I15/2 transition in the 4f orbital of erbium resulting in an emission at ∼ 1.5 μm, which is the low loss window of silica optical fibres. The limited erbium concentration of about 1020 ions/cm3 in inorganic erbium-doped glasses and the low absorption coefficient of the Er3+ ions, imply that relatively long lengths of fibre are required. Organic erbium complexes present higher absorption cross sections due to the photosensitization of erbium by the organic conjugated ligands and broader emission bands than those of the free Er3+ ions. Such properties open the possibility to develop compact, low power and broadband infrared emitting devices. We present the study of an organic fluorinated erbium complex exhibiting 1.5 μm luminescence lifetime of several hundreds of microseconds measured on thin film. The organic complex has been deposited by vacuum sublimation technique. This deposition method allows the realization of an erbium-doped thin film without the help of an organic polymer matrix, which is a potential source of vibrationnal luminescence quenching. We report the synthesis, the sublimation process, and the characterization of the thin films. The chemical structure of the complex is assessed by FTIR, NMR and MALDI-TOF. Chemical integrity of the thin film after vacuum deposition is determined by FTIR. The morphology of the thin film is characterized by X-ray diffraction experiments. The optical properties of the thin film are determined by spectroscopic ellipsometry, UV-Vis-NIR absorption spectroscopy and time resolved NIR photoluminescence spectroscopy.

Due to environmental concerns traditional eutectic tin-lead solder is gradually being replaced in electronic assemblies by “lead-free” solders. During this transition, nanoparticle technology is also being investigated to see whether improvements in joint reliability for high temperature applications can be made. Nanoparticles can be used to harden the solder via Zener pinning of the grain boundaries and reduce fatigue failure. This paper explores the effects of adding Silica nanoparticles to SnAgCu solder, and how the mechanical properties induced in the solder vary with temperature. It is found that above 100 °C the mechanical response and microstructure of the normal and nanoparticle enhanced solders converge.

CdSe/CdS colloidal nanocrystals are light-emitting nanoparticles with remarkable optical properties such as suppressed fluorescence blinking and enhanced emission from multiexciton states. These properties have been attributed to the suppression of non-radiative Auger recombination. In this work we employ ultrafast spectroscopy techniques to identify optical signatures of neutral and charged excitonic and multiexcitonic states.

In this work, we report the effects of curing time on properties of SiO2 films produced from Spin-On Glass (SOG) diluted with H2O and cured at 200°C. The electrical characterization showed that the insulator breakdown field for the films produced from SOG diluted with H2O with 1 Hr of curing time was approximately 5 MV/cm while for 6.5 Hrs of curing time the breakdown field was 21 MV/cm. Also, the refractive index and surface roughness were improved with longer curing time.

ZnO nanostructures such as nanorods and nanoneedles were prepared on both cotton textiles and electrospun cellulosic nanofibers by a simple, two-step hydrothermal process at low temperature in aqueous solution. Commercially available cotton fabrics were used. Cellulosic nanofibers (average diameters of 100 nm) were obtained by electrospinning of cellulose acetate/polyvinyl acetate/polyethylene glycol mixture on glass slides to form non-woven mats.

On cotton textiles, the systematic change of the seed-to-growth solution concentration ratio caused a noticeable variation on the morphology of the nanostructures. The loading ratio of ZnO nanorods and nanoneedles were 37.5% and 18.1 wt%, respectively. Durable superhydrophobicity was achieved with a static water contact angle of 160.7° upon fluorosilane treatment, even after prolonged exposure to UV and plasma irradiation. The surface wettability was found to slightly vary from nanorods (160.7°) to nanoneedles (159.8°). The ZnO nanostructures did not lose their superhydrophobicity after 1 h of agitation in DI water. Excellent UV blocking activities were observed for nanorods and nanoneedles in the wavelength region analyzed. On electrospun cellulosic nanofibers of approximately 100 nm diameter, the loading ratio of ZnO nanorods were found to be 33.3 wt% which are densely and uniformly distributed the entirety of the nanofibers. Although diameters of the nanofibers and cotton fibers are very different in size (around 100 nm and 15-20 micron, respectively) the ZnO loading on electrospun fibers are very close to that of cotton fabric due to the high surface area and coiled nature of electrospun fibers, resulting in high packing density. ZnO nanorods grown on electrospun nanofibers exhibited hydrophilic behavior.

Mismatched or shadowed individual cells in a module can operate in the Reverse Bias (RB) regime. Subjecting a dye solar cell (DSC) to an accelerated RB stress by forcing a constant current equal to 2-fold its ISC, produced significant alterations on the current-voltage (I-V) characteristics in RB with time and a severe loss of cell efficiency in 32h. We investigated and identified a key mechanism for RB charge transfer and degradation in DSCs. I-V characteristics in RB were found to be sensitive to the type of dye utilized and to TiCl4 substrate treatment.

In this paper, efficacy of p-n junction p-CuO/n-ZnO composite is assessed as a potential photocatalyst by monitoring degradation of methylene blue (MB) in the presence of UV light. The p-n junction photocatalyst, p-CuO/n-ZnO, was prepared by ball milling of ZnO and CuO in water. The structural properties of p-CuO/n-ZnO composite were characterized by x-ray diffractometer and surface charge properties via zeta potential measurement. The degradation of MB in the presence of composite powder was monitored via UV-vis spectrometer. Various studies affecting the degradation rate of MB were conducted as a function of weight fraction of CuO in the composite and ball milling time. The highest degradation rate of MB was achieved in CuO (10 Wt.%)/ZnO for which high negative zeta potential was recorded. The MB degradation efficiency was found to decrease with the samples ball milled for time longer than 12 hours due to increased agglomeration of particles. The mechanisms that influence the photocatalytic activity of p-CuO/n-ZnO are discussed based on the p-n junction principle.