Sellafield Ltd operates a Waste Vitrification Plant (WVP) to immobilise the arisings from the reprocessing of spent nuclear fuel. Washout of solids from the base of waste storage tanks in preparation for decommissioning is likely to produce feeds enriched in molybdenum to the WVP. Vitrification of such feeds in the borosilicate glass formulation currently used by the WVP for vitrification of reprocessing waste has been investigated to determine the maximum achievable loading of MoO3.

The vitrification of molybdenum in the absence and presence of reprocessing waste was studied. A number of glasses were manufactured in the laboratory containing various waste loadings. The resultant glasses were examined both visually and under the scanning electron microscope for the presence of any phase separation. Additional aluminium was added to the glasses manufactured in the absence of reprocessing waste to improve the durability of the glass. In borosilicate glass containing 3.5 wt% Al2O3 the onset of a molybdenum phase separation was observed in glasses containing 2.6 wt% MoO3. In the presence of Magnox reprocessing waste, phase separation was observed when the product contained >3.8 wt% MoO3. Soxhlet durability testing of a selection of the glasses manufactured was carried out. The Soxhlet durability of glasses in the absence of phase separation was good.

Nuclear Magnetic Resonance (NMR) technique is a convenient method to monitor magnetic nanoparticles in different biomedical applications and observe changes induced by the particles. To better understand the specifics of the magnetic resonance and spin relaxation in the systems with magnetic nanoparticles, the NMR spectra and magnetization dynamics of the host protons are studied in the model systems of different viscosity and some biological systems in the presence of magnetic nanoparticles. The results confirmed that nanoparticles affect the proton relaxation kinetics of liquid solutions, changing the relaxation time (T1) significantly, whereas in systems of high viscosity the relaxation times are unchanged. The kinetics in intermediate systems is multi-exponential. A complicated picture is observed in biological systems, demonstrating contributions of liquid-like and solid-like behavior.

Under γ-irradiation, thiacetamide (TAA) releases S2− in acidic solutions (e.g., pH = 3), and the S2− can react with available Cd2+ in soft templates to form CdS nanorods. Single-crystalline CdS nanorods were prepared in this study. The effects of various synthesis parameters on the crystalline type, morphology, average particle size, and photoelectric properties were thoroughly investigated, including the concentrations of reactants, dose of irradiation, and the type and dosage of templates. The structure and selected physical and chemical properties of products were characterized by x-ray diffraction (XRD), Fourier transform infrared (FTIR), ultraviolet-visible (UV-vis), selected area electron diffraction (SAED), transmission electron microscopy (TEM), and photoluminescence (PL) spectrophotometer techniques. Results indicated that the ratio of reactants to templates greatly affected the morphology of CdS nanorods; the types of soft templates also had significant effects on the morphology and crystalline type of the nanorod products.

This paper presents a new programmable particle manipulation using a lab-on-a-display platform, which is a kind of optoelectrofluidic platform applying a liquid crystal display (LCD) as a display device for generating virtual electrodes in optoelectronic tweezers. The reconfigurable virtual electrodes in the lab-on-a-display are more advantageous than other devices which apply the micro-patterned electrodes, because we can freely control the size and position of electrodes as well as the voltage conditions, which affect the particle movements such as concentration and separation of particles. Due to its simple structures, cheap manufacturing costs, and high performances, this new LCD-based optoelectrofluidic platform can be applied to the interactive manipulation of polystyrene microspheres and blood cells. In addition, a method to discriminate normal oocytes for in vitro fertilization is demonstrated by combining the gravity effect with the optically induced positive dielectrophoresis (DEP). The discrimination performance can be enhanced due to the reduction of friction forces acting on the oocytes which are relatively large and heavy cells being affected by the gravity field. With the same device, we also demonstrate the size-dependent microparticle separation as well as the local concentration and assembly of microparticles originated from the image-driven AC electrokinetics such as DEP and AC electroosmosis. The particle movements result from the frequency-dependent behavior according to the particle diameter. This novel technique can be applied to rapidly concentrate, separate and pattern micro-/nanoparticles and biomolecules in many biological and chemical applications.

In this work, Pt and Pt-Ru nanoparticles were synthesized on both single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). Effects of different nanotube supports on electrocatalytic activity of Pt and Pt-Ru nanoparticles for methanol and ethanol oxidations were investigated using cyclic voltammetry and electrochemical impedance spectroscopy. In comparison to MWCNTs, SWCNT supported Pt and Pt-Ru catalysts demonstrate better electrocatalytic activities in terms of forward peak current density, the ratio of forward peak current density to reverse peak current density, and charge transfer resistance. This study indicates that SWCNTs can serve as effective catalyst supports for both direct methanol and ethanol fuel cells.

A modified heat treatment process designated quenching–partitioning–tempering (Q–P–T) process is developed based on the quenching and partitioning process proposed by J.G. Speer et al. [Acta Mater.51, 2611 (2003)] and D.K. Matlock et al. [Mater. Sci. Forum426–432, 1089 (2003)]. A Fe–0.485C–1.195Mn–1.185Si–0.98Ni–0.21Nb steel after Q–P–T process satisfies the designed requirement of tensile strength over 2000 MPa and elongation over 10%. The microstructure characterization indicates that this ultrahigh-strength steel consists of nanomicrostructures including lath martensite, filmlike retained austenite, and dispersive Nb-containing carbides. The effect of tempering time on the mechanical properties is analyzed based on microstructures.

Zinc oxide (ZnO) nanowires (NWs) are receiving significant industrial and academic attention for a variety of novel electronic, optoelectronic and MEMS device applications due to their unusual combination of physical properties, including being optically transparent, semiconducting and piezoelectric. Hydrothermal growth is possible at significantly lower temperatures (and hence lower thermal budgets) compared with other NW growth methods, such as chemical vapour deposition. In this context, the hydrothermal growth of ZnO NWs on seeded substrates immersed in equimolar zinc nitrate/HMTA aqueous solution was investigated. NWs were grown on polished silicon (001) substrates, and the solution concentrations, temperatures and growth times were varied. Importantly, the NW diameter was found to depend only on concentration during hydrothermal growth for times up to 4 hours. The average diameter was 14 nm in 0.005 M solution and increased up to a maximum 150 nm at 0.07 M, when the NWs formed a continuous polycrystalline film. Concentration and temperature were all found to affect the axial growth rate of NWs in the [0001] direction. The growth rate was constant up to 4 hours (200 nm hr-1) for constant conditions (81 oC, 0.025 M). The growth rate was found to increase approximately linearly with concentration at a rate of 7840 nm M-1 hr-1 up to 0.06 M (81 oC solution). The growth rate also increased linearly with temperature at a rate of 4.9 nm hr-1 K-1 (0.025 M solution). This indicates that growth takes place close to the equilibrium point, found by linear regression to be 36 oC for 0.025 M solution.

Silicon carbide is one of the most studied materials for core components of the next generation of nuclear plants (Gen IV). In order to overcome its brittle properties, materials with nanometric grain size are considered. In spite of the growing interest for nano-structured materials, only few experiments deal with their behaviour under irradiation. To assess and predict their evolution under working conditions, it is important to characterize their microstructure and structure. To this purpose, we have studied microcrystalline and nanocrystalline samples before and after irradiation at room temperature with 4 MeV Au ions. In fact, it is well established that such irradiation conditions lead to amorphisation of the material, which can be restored after annealing at high temperature. We have performed isochronal annealings of both materials to point out the characteristics of the healing process and eventual differences related to the initial microstructure of the samples. To this purpose Grazing Incidence X-Ray Diffraction has been performed to determine the microstructure and structure parameters. We observe the amorphisation of both samples at similar doses but different annealing kinetics are observed. The amorphous nanocrystalline sample recovers its initial crystalline state at higher temperature than the microcrystalline one. This effect is clearly related to the initial microstructures of the materials. Therefore, the grain size appears as a key parameter for the structural stability and mechanical properties of this ceramic material under irradiation.

In this paper, the undoped SrTiO3 (STO) and Indium doped STO (SrTi1-xInxO3: STIO) thin films were grown on Pt/Ti/SiO2/Si substrates by pulsed laser deposition with low substrate temperature. For undoped STO film, the influences of the forming processes on their resistive switching properties were studied by current and voltage controlled I-V sweeps, respectively. An obvious current controlled negative differential conductance phenomenon was found in both polarities of the electrical field. However, for low Indium doped STIO (x=0.1), the filament related resistance switching was observed in both the current and voltage I-V sweeps. And for high Indium doped STIO (x=0.2), a resistance switching with a reverse direction change to that in undoped STO can be obtained by a proper forming process. Based on these results, the reversible change of the Schottky like barrier at the grain boundary by the migration of oxygen vacancies were proposed to interpret the mechanism of the resistance switching.

In this paper, we present a compact lab-on-chip system suited for label-free DNA analysis. The system can be fabricated on a conventional microscope glass slide using thin-film and thick-film technologies. It integrates a heating chamber, an electrowetting-based droplet handling system and a hydrogenated amorphous silicon (a-Si:H) photosensor array for DNA detection. At this stage of research we have designed and tested the individual functional units. The heating chamber incorporates a thin metal film heater optimized for uniform temperature distribution on a 1cm2 area. A forward-biased a-Si:H p-i-n junction is used for temperature monitoring, achieving a linear temperature dependence with -3.3 mV/K sensitivity. The droplet-handling unit, relying on the electrowetting method, is designed to move the sample from the heating chamber to the sensor array. The unit includes a set of metal pads beneath a layer of PDMS that provides both the electric insulation of the electrodes and the hydrophobic surface needed by the electrowetting technique. The UV sensor array allows measuring the DNA absorbance variation at 254nm related to the hybridization between probe-molecules contained in the sample and reference target molecules immobilized on the sensor surface. A preliminary test to detect the hybridization between a 25-mer single-stranded oligonucleotides and denaturated pBR 322 4162-mer single-stranded oligonucleotides has been carried out successfully.

We have built and tested electrically small (∼γ/10) resonant patch antennas as proposed in recent literature [1, 2]. The metamaterial array loading the antennas formed a rough cylinder axially enclosed by a patch antenna and a ground plane. The fill ratio, or ratio of the metamaterial array's radius to the patch radius, was less than one. Given a particular negative permeability metamaterial (copper spiral rings printed on circuit board in this case), the fill ratio dictates the lower of two resonant frequencies of the antenna. The higher frequency resonance is characteristic of the patch.

We observed that each of the antennas radiated at two resonant frequencies, as predicted. The lower frequency resonance disappeared when the metamaterial was removed. We built two versions of this antenna, one (Design I) with a lower resonant frequency of 756 MHz and higher resonant frequency of 3.3 GHz, and a second antenna (Design II) with a lower resonant frequency of 385 MHz and higher resonant frequency of 1.8 GHz. Because we were interested in reducing the size of patch antennas, we focused on the lower frequency resonances in this work. The antennas' return loss was measured at -23 dB and -28 dB, the gains were -11 dBi and -13 dBi, and the return loss was less than -10 dB over bandwidths of 4.7% and 1.8% for the lower frequency resonances of Design I and Design II, respectively.

We also predicted the trend of increasing resonant frequency with decreased metamaterial fill ratio. We varied the fill ratio was by changing the patch size while maintaining the same metamaterial array. As predicted, resonant frequency increased with increasing patch size, an opposite trend to what one would expect without the loading metamaterial. Altering the patch size allows simple tuning during the assembly and test process.

A multiscale finite element model has been developed to study the fracture behaviour of two-dimensional random Voronoi structures. The influence of materials parameters and cellular architecture on the damage initiation and accumulation has been analyzed. The effect of the solid material’s strain hardening, relative density and architectural randomness on the ductility and fracture strength of the cellular solid are investigated. The results suggest materials-design directions in which the heat treatment, the solid material properties, its microstructure and the cellular architecture can be tuned for an optimized performance of cellular materials.

Aluminum Nitride (AlN) films were grown using Metal Organic Vapor Phase Epitaxy (MOVPE) techniques on Si (111) substrates patterned with SiOx stripes and the vibrational properties of these films were investigated by Fourier transform infrared (FTIR) techniques. The grown films contained a predominantly wurtzite AlN phase in addition to oxidized aluminum and mixed AlN phases. The AlN film on amorphous silicon oxide (SiOx) was prone to corrosion when subjected to wet etching in buffered hydrofluoric acid solution thereby changing the material properties of the AlN film on SiOx. The etching process significantly reduced the oxidized aluminum phase and mixed AlN phases.

In this paper, we demonstrate a perfectly-ordered microbowl array with balanced dielectrophoresis (DEP) for a high-throughput single-cell analysis. In order to fabricate well-ordered microbowl array in a large area, we utilized three-dimensional diffuser lithography for photoresist mold and nickel electroplating technique for final microbowl structures on a silicon substrate. Single microbowl has six sharp apexes surrounding the microbowl perimeter. Each microbowl has a diameter of 10 μm, and a height of 9 μm, which can be controllable by patterns on mask and lithography conditions. To investigate feasibility for application to the microbowl array as a single-cell microarray, we used latex beads of 6.4 μm in an average diameter to be captured by dielectrophoretic force. The nickel microbowl array densely packed with a hexagonal geometry played as a bottom electrode, and an ITO-coated glass covered the nickel microbowl array as a top electrode while keeping a uniform gap between two electrodes. After injecting solution containing latex beads through the gap, we applied an AC signal (2 VPP, 1 MHz) between two electrodes to induce high electric field near the sharp apexes of the single microbowl. A negative DEP trap is formed at the center of the single microbowl with balanced DEP force from the six apexes. The experimental result shows that injected latex beads had been successfully and uniformly aligned and trapped at the microbowl array sustained by negative DEP.

Pure and Cu-doped quantum dots of ZnSe@ZnS were synthesized in aqueous phase using microwave irradiation at 140 °C. X-ray diffraction analyses suggested the development of a ZnSe-ZnS structure. UV-vis measurements evidenced that the presence of Cu species in quantum dots caused the blue shift of exciton peaks with respect to pure, i.e. non doped ones. Photoluminescence spectra of quantum dots synthesized at Zn/Cu mole ratios of 1/0.001 and 1/0.005 exhibited a very strong emission peak centered on ˜ 515 nm. On the contrary, a weak emission peak was observed at 412 nm in pure ZnSe@ZnS quantum dots. The observed emission at 515 nm was attributed to the internal doping of Cu species, which should have induced d-d transitions in the host lattice. Quenching of the luminescence at 515 nm was observed for nominal Cu concentrations above 0.005 mM.

Vascular smooth muscle cell migration is a microscopic in vivo process where specific cells crawl in order to partake in crucial physiological functions relating to embryonic development, wound healing, and tissue development. Abnormalities of cell migration result in pathologies such as tumor metastasis, angiogenesis, chronic inflammation, and various immune response dysfunctions. The mechanism behind cellular migration and the role of intracellular proteins in the instigation of cell directionality remains poorly understood without effective biomedical device available. The development of microfluidic biochips technologies enable detection, sample preparation and treatment on one single chip. We are reporting the design and fabrication of a novel microfluidic trip for guiding and quantifying cell migrations. The chip featured micropillar arrays imbedded in a multichannel microfluidic chip, where cell migration can be guided by utilizing the characteristics of laminar flow. Non-blending layers of fluid injected through the multi-channel device simulated a wounded edge across a monolayer of cells by limiting flow of trypsin, a serine protease, to half of the main channel, promoting cell migration in a desired direction. Control over cell directionality allows for the measurement and analysis of mechanical forces generated during cell migration in relation to migratory responses from intracellular protein inhibition. The micro-fluidic chip template was designed and manufactured using photolithography techniques. Polydimethylsiloxane (PDMS) served as the bulk material of the two compromising chip layers (channels and pillars), which were subsequently aligned and adhered to form the device. It was confirmed through both computer simulation and experimentation that the through optimized arrangement of the chip design, this device can effectively hold laminar flows of trypsin and cell media. Thus, this microfluidic device allows the user to simultaneously acquire force data during cell migration and observe migratory patterns to ultimately gain a better understanding of the underlying mechanisms of cell migration and directionality.

For the first time, patterned growth of boron nitride nanotubes (BNNTs) on Si substrates has been achieved by catalytic chemical vapor deposition (CCVD). Following the boron oxide chemical pathway and our growth vapor trapping approach, high quality and quantity BNNTs can be produced. Effective catalysts have been found to facilitate the growth of BNNTs, while some critical parameters of the synthesis have also been identified to control the quality and density. The success of patterned growth of high quality BNNTs not only explains the roles of the effective catalysts during the synthesis process, but could also be of technologically important for future device fabrication.

This paper presents a combined experimental and theoretical/computational study of adhesion and interfacial fracture between multilayers in a CYPHER® model drug eluting stents (DES). Atomic Force Microscopy (AFM) is used to obtain pull-off forces between coated AFM tips and substrates that simulate the bimaterial surfaces in the DES. Adhesion theories and fracture mechanics concepts are then applied to obtain estimates of the fracture toughness over a range of mode mixities between pure mode I and pure mode II. The trends in the estimates are shown to be in good agreement with experimental measurements of interfacial fracture toughness obtained from Brazil disk specimens over the same range of mode mixities.

The influence of the growth temperature on the phase stability and composition of single-phase In1-xGaxN epilayers has been studied. The In1-xGaxN epilayers were grown by high-pressure Chemical Vapor Deposition with nominally composition of x = 0.6 at a reactor pressure of 15 bar at various growth temperatures. The layers were analyzed by x-ray diffraction, optical transmission spectroscopy, atomic force microscopy, and Raman spectroscopy. The results showed that a growth temperature of 925°C led to the best single phase InGaN layers with the smoothest surface and smallest grain areas

Superparamagnetic nanoparticles can find many applications in different fields with greener techniques. The Fe3O4 nanoparticles less than 10nm coated with humic acid were synthesized by a chemical co-precipitation technique with cheap and environmental friendly iron salts and humic acid. The as-synthesized products were highly soluble in water. The efficacy for liver Magnetic resonance imaging (MRI) contrast agent was investigated by using it to the live rat and tumor-bearing rabbit models, on a conventional clinical 1.5 T MRI facility. Moreover the Fe3O4 –HA composite used in the Methylene Blue adsorption in neutral aqueous solution was studied too with high efficiency. The experimental results showed that the humic acid coated Fe3O4 superparamagnetic nanoparticles were suitalbe not only for liver MRI contrast agent, but also as adsorbents for removal of cationic organic dyes from neutral water.