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Summary: Thin films of vertically aligned tungsten nanorods were used to enhance field ionization in pyroelectric crystal D–D fusion experiments resulting in increased neutron production. The tungsten nanorods were deposited on a single LiTaO3 crystal using sputter deposition at glancing angles. The combination of a single tungsten tip with a thin film of nanorods on the face of the crystal yielded about four times the number of neutrons than did either a single tip or nanorods alone. [Copyright &y& Elsevier]

Abstract: Pulsed laser ablation of Al in aqueous solutions could generate hollow Al2O3 particles due to laser-induced bubbles, but the generation depends on the laser wavelength. Herein, the structural evolution of amorphous and hollow Al2O3 spheres produced by 248nm laser ablation in water–ethanol mixture has been studied. The amorphous phase could crystallize into γ-Al2O3 by thermal annealing while maintaining the shell structure. The 248nm laser-induced photodissociation of water and ethanol could aid the formation and increase the lifetimes of bubbles, which are critical for the formation of hollow particles. [Copyright &y& Elsevier]

Two photon polymerization involves nearly simultaneous absorption of ultrashort laser pulses for selective curing of photosensitive material. This process has recently been used to create small-scale medical devices out of several classes of photosensitive materials, such as acrylate-based polymers, organically-modified ceramic materials, zirconium sol-gels, and titanium-containing hybrid materials. In this review, the use of two photon polymerization for fabrication of several types of small-scale medical devices, including microneedles, artificial tissues, microfluidic devices, pumps, sensors, and valves, from computer models is described. Necessary steps in the development of two photon polymerization as a commercially viable medical device manufacturing method are also considered. [ABSTRACT FROM AUTHOR]

Core-shell like structured barium zirconium titanate-barium calcium titanate-poly(methyl methacrylate) [(Ba 0.94 Ca 0.06 )(Zr 0.16 Ti 0.84 )O 3 -PMMA] nanocomposites were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of methyl methacrylate (MMA) from the surface of BZT-BCT nanoparticles. X-ray diffraction patterns of pure polymer and BZT-BCT nanoparticles revealed their amorphous and polycrystalline natures respectively. Fourier transform infrared spectroscopy confirmed the grafting of the PMMA shell on the surface of the BZT-BCT nanoparticles cores. Transmission electron microscopy (TEM) results revealed that BZT-BCT nanoparticles were covered by a very thin layer of PMMA forming a core-shell like structure and thermogravimetric analysis results showed that the grafted BZT-BCT-PMMA nanoparticles consist of ∼80.1% PMMA by weight. Polymer grafted BZT-BCT nanocomposite thick films (∼10 μm) have shown an improved dielectric constant (ε∼56), a high breakdown field strength (∼3 MV/cm) and high-energy storage density ∼22.5 J/cm 3 . The improved electrical properties of core-shell like structured BZT-BCT-PMMA nanocomposites were attributed to improved nanoparticle dispersion and enhanced interfacial polarization due to the covalent linkage between polymer and nanoparticle interface. Mechanically stable and homogeneous composite films were obtained using the surface grafted BZT-BCT ceramic nanoparticles. [ABSTRACT FROM AUTHOR]

Rare-earth (Sm) and transition metal (Co) modified polycrystalline BiFeO3 (BFO) thin films have been deposited on Pt/TiO2/SiO2/Si substrate successfully through pulsed laser deposition (PLD) technique. Piezoelectric, leakage current and temperature dependent dielectric and magnetic behaviour were investigated for the films. Typical "butterfly-shaped" loop were observed in BSFCO films with an effective piezoelectric constant (d33) ~94 pm/V at 0.6 MV/cm. High dielectric constant ~900 and low dielectric loss ~0.25 were observed at room temperature. M-H loops have shown relatively high saturation magnetization ~35 emu/cm³ at a maximum field of H ~20 kOe. Enhanced magnetoelectric coupling response is observed under applied magnetic field. The multiferroic, piezoelectric, leakage current behaviours were explored. Such studies should be helpful in designing multiferroic materials based on BSFCO films. [ABSTRACT FROM AUTHOR]

With the motivation to employ BaO–B2O3–ZnO for high performance capacitors by using viscous flow/liquid phase sintering, the microstructures, phases, and dielectric properties of BaO–B2O3–ZnO films prepared by pulsed laser deposition were examined as a function of heat-treatment. The glass transition temperature (Tg) and crystallization temperature of the films are ~536°C and 640°C, respectively. The phases in the films are quite complicated after heat-treated above 700°C until 900°C where the film is dominated by a single phase. Zn concentration is reduced after heat-treatment at high temperature due to segregation and evaporation. The dielectric constant of the film decreases with the increasing heat-treatment temperature, probably due to Zn reduction, Si diffusion, and crystallization of the film. Experimental data shows that ~700°C is the optimal temperature to use the low melting glass BaO–B2O3–ZnO to make high performance capacitors by viscous flow/liquid phase sintering. [ABSTRACT FROM AUTHOR]

Abstract: The ability to precisely pattern embryonic stem (ES) cells in vitro into predefined arrays/geometries may allow for the recreation of a stem cell niche for better understanding of how cellular microenvironmental factors govern stem cell maintenance and differentiation. In this study, a new gelatin-based laser direct-write (LDW) technique was utilized to deposit mouse ES cells into defined arrays of spots, while maintaining stem cell pluripotency. Results obtained from these studies showed that ES cells were successfully printed into specific patterns and remained viable. Furthermore, ES cells retained the expression of Oct4 in nuclei after LDW, indicating that the laser energy did not affect their maintenance of an undifferentiated state. The differentiation potential of mouse ES cells after LDW was confirmed by their ability to form embryoid bodies (EBs) and to spontaneously become cell lineages representing all three germ layers, revealed by the expression of marker proteins of nestin (ectoderm), Myf-5 (mesoderm) and PDX-1 (endoderm), after 7 days of cultivation. Gelatin-based LDW provides a new avenue for stem cell patterning, with precision and control of the cellular microenvironment. [ABSTRACT FROM AUTHOR]

A laser-based transfer technique, termed matrix assisted pulsed laser evaporation direct write (MAPLE DW), has been modified to rapidly and accurately deposit mammalian cells in a non-contact manner. While this technology was originally developed for deposition of inorganic materials, it has shown the ability to transfer of a wide range of biological materials. Two types of mammalian cells, human osteosarcoma and rat cardiac cells were deposited into a biopolymer matrix via MAPLE DW. Current results show that it is possible to deposit cells in a stepwise manner and build cellular ‘stacks’ 50–100 μm tall. Furthermore, the technique is now capable of depositing cells with near single cell resolution. Post-transfer results of live/dead viability/cytotoxicity assays show that the cells are unaffected by the process with near 100% viability. The ability to build cellular structures in three dimensions and deposit small numbers of cells accurately has potential application to tissue engineering. [Copyright &y& Elsevier]

Abstract: The electronic properties of a-Si:H vary with hydrogen passivation of dangling bond defects. It appears this effect is also operative in semiconducting amorphous hydrogenated boron carbide (a-B5C:H). Therefore, the ability to quantify the amount of hydrogen will be key to development of the materials science of a-B5C:H. The results of an initial investigation probing the ability to quickly correlate hydrogen concentration in a-B5C:H films with infrared spectroscopy are reported. a-B5C:H thin films were growth on Si (111) substrates by plasma-enhanced chemical vapor deposition (PECVD) using sublimed orthocarborane and argon as the precursor gas. Nuclear reaction analysis (NRA) was performed to quantify the atomic concentration of H in the a-B5C:H films. While the observed vibronic structure does not show stretches due to terminal C–H or bridging B–H–B, analysis of the terminal B–H stretch at ∼2570cm−1 gives a proportionality constant of A =2×1022 cm−2. We conclude that the methods previously developed for correlating H concentration to infrared data in a-Si:H are similarly viable for a-B5C:H films. [Copyright &y& Elsevier]