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We have shown that the magnetic properties of nanoparticles may be tuned from superparamagnetic to ferromagnetic by changing the substrate or thin film matrix in which they are embedded. Nickel nanoparticles were embedded into alumina, titanium nitride, and cerium oxide matrices on both silicon and sapphire substrates via pulsed laser deposition. The laser ablation time on the nickel target was kept constant. Only nickel nanoparticles in cerium oxide showed characteristics of ferromagnetism (room temperature coercivity and remanence). Ni nanoparticles, in either alumina or titanium nitride, possessed blocking temperatures below 200 K. Detailed scanning transmission electron microscopy analysis has been conducted on the samples embedded into cerium oxide on both substrates and related to the magnetic data. [ABSTRACT FROM AUTHOR]

The solution blow spinning technique was used to fabricate a new biocomposite fibrous mat consisting of natural rubber (NR) and polyhydroxybutyrate (PHB) bioblend, with various loads of 45S5 bioglass (BG) particles. According to SEM analysis, NR fibers exhibited ribbon‐like morphologies, whereas the addition of PHB resulted in improved fiber formation and a reduction in their diameter. In NR‐PHB/BG biocomposites with varying BG loadings, typical thermal degradation events of PHB (stage i) and NR (stage ii) were observed. In comparison with pure PHB, the TG/DTG curves of NR‐PHB/BG specimens revealed a lower stage i degradation peak. Such an outcome is possibly due to the fact that PHB in the NR‐PHB fibers is located predominantly at the surface, that is, PHB is more susceptible to thermal degradation. The NR‐PHB/BG biocomposite possessed an increased stiffness due to the addition of PHB and BG, resulting in an increased stress and a decreased strain at rupture compared to the pure NR and NR‐PHB mats. DMA analysis revealed two well‐defined regions, above and below the glass transition temperature (Tg), for the storage modulus (E') of the NR‐PHB/BG specimens. The values of E' were in both regions for NR‐PHB/BG specimens increased at higher BG content. The measured tanδ = E″/E' was used to determine the Tg value for all specimens, with Tg found to be in the −49 to −46°C range. Finally, NR‐PHB/BG biocomposite fibrous were proven noncytotoxic by in‐vitro testing on fibroblasts. These biocomposites enhanced cell growth, holding great promise for tissue engineering applications. Highlights: Solution blow spinning technique was used to produce three‐phase biocomposite specimens.NR‐PHB/BG fibrous mat specimens with a diameter of 9–10 μm were obtained.Although high BG loads are applied to the NR‐PHB/BG specimens, they remain elastic and flexible.Fibrous biocomposite mats enhance cell growth and possess great potential for tissue engineering. [ABSTRACT FROM AUTHOR]

The magnetic characteristics of iron nanoparticles embedded in an alumina thin film matrix have been studied as a function of spacer layer thickness. Alumina as well as iron nanoparticles were deposited in a multilayered geometry using sequential pulsed laser deposition. The role of spacer layer thickness was investigated by making layered thin film composites with three different spacer layer thicknesses (6, 12, and 18 nm) with fixed iron particle size of ∼13 nm. Intralayer magnetic interactions being the same in each sample, the variation in coercivity and saturation magnetization is attributed to thickness dependent interlayer magnetic interactions of three types: exchange, strong dipolar, and weak dipolar. A thin film composite multilayer structure offers a continuously tunable strength of interparticle dipole-dipole interaction and is thus well suited for studies of the influence of interaction on the magnetic properties of small magnetic particle systems. [ABSTRACT FROM AUTHOR]

Abstract: Pulsed laser ablation (PLA) has recently been used to synthesize metal and ceramic nanostructures. The PLA method is highly advantageous because nanoparticle (NPs) synthesis is possible without organic binders or expensive equipment required to obtain high vacuum. In this letter we report on the synthesis and magnetic properties of ZnO nanoparticles by PLA of a solid ZnO target in water. The mean size of the ZnO NPs is ∼100nm after dispersion. The ZnO NPs show clear characteristics of room temperature ferromagnetism. The saturation moment (Ms) of the ZnO NPs is almost unchanged with temperature, which suggests that the fundamental mechanism is different than the traditional double exchange model. So-called d0 magnetism has been invoked to explain the magnetic characteristics. [Copyright &y& Elsevier]

We investigate the effect of nickel nanoparticle size on thermal transport in multilayer nanocomposites consisting of alternating layers of nickel nanoparticles and yttria stabilized zirconia (YSZ) spacer layers that are grown with pulsed laser deposition. Using time-domain thermoreflectance, we measure thermal conductivities of k=1.8, 2.4, 2.3, and 3.0 W m-1 K-1 for nanocomposites with nickel nanoparticle diameters of 7, 21, 24, and 38 nm, respectively, and k=2.5 W m-1 K-1 for a single 80 nm thick layer of YSZ. We use an effective medium theory to estimate the lower limits for interface thermal conductance G between the nickel nanoparticles and the YSZ matrix (G>170 MW m-2 K-1), and nickel nanoparticle thermal conductivity. [ABSTRACT FROM AUTHOR]

We examine the thermal conductivity k and interface thermal conductance G for amorphous and crystalline Zr47Cu31Al13Ni9 alloys in contact with polycrystalline Y2O3. Using time-domain thermoreflectance, we find k=4.5 W m-1 K-1 for the amorphous metallic alloy of Zr47Cu31Al13Ni9 and k=5.0 W m-1 K-1 for the crystalline Zr47Cu31Al13Ni9. We also measure G=23 MW m-2 K-1 for the metallic glass/Y2O3 interface and G=26 MW m-2 K-1 for the interface between the crystalline Zr47Cu31Al13Ni9 and Y2O3. The thermal conductivity of the crystalline Y2O3 layer is found to be k=5.0 W m-1 K-1, and the conductances of Al/Y2O3 and Y2O3/Si interfaces are 68 and 45 MW m-2 K-1, respectively. [ABSTRACT FROM AUTHOR]

Polymers are most widely used in the production of water-repellant coatings. However, their use in applications requiring wear resistance or high-temperature stability is extremely limited. A recent report suggests that wear resistant, thermally stable rare earth oxide materials like cerium dioxide (ceria) are intrinsically water repellant. We have studied this intriguing finding for ceria thin films fabricated by pulsed laser deposition (PLD) at different oxygen pressures and different substrate temperatures. We used a custom apparatus for measuring water contact angles on ceria films deposited by PLD. X-ray photoelectron spectroscopy was used to determine the relationship between the ceria wetting behavior and ceria surface chemistry. Our results show that ceria thin films are intrinsically hydrophilic and that hydrophobicity arises due to adsorption of hydrocarbon species after ~24 h. [ABSTRACT FROM AUTHOR]

Conversion of carbon dioxide (CO2) into fuels is an attractive solution to many energy and environmental challenges. However, the chemical inertness of CO2 renders many electrochemical and photochemical conversion processes inefficient.We report a transition metal dichalcogenide nanoarchitecture for catalytic electrochemical CO2 conversion to carbon monoxide (CO) in an ionic liquid.We found that tungsten diselenide nanoflakes show a current density of 18.95 milliamperes per square centimeter, CO faradaic efficiency of 24%, and CO formation turnover frequency of 0.28 per second at a low overpotential of 54 millivolts.We also applied this catalyst in a light-harvesting artificial leaf platform that concurrently oxidized water in the absence of any external potential. [ABSTRACT FROM AUTHOR]

This work deals with the anti-icing behavior at subfreezing temperatures of CeO2/polyurethane nanocomposite coatings with and without a stearic acid treatment on aluminum alloy substrates. The samples ranged from superhydrophilic to superhydrophobic depending on surface morphology and surface functionalization. X-ray photoelectron spectroscopy was used to determine the surface composition. The anti-icing behavior was studied both by importing fog into a chamber with controlled atmosphere at subzero temperatures and by conducting experiments with drop impact velocities of 1.98, 2.8, 3.83, and 4.95 m/s. It was found that the ice-phobicity of the ceramic/polymer nanocomposite coating was dependent on the surface roughness and surface energy. Water drops were observed to completely rebound from the surface at subfreezing temperatures from superhydrophobic surfaces with small contact angle hysteresis regardless of the impact velocity, thus revealing the anti-icing capability of such surfaces. [ABSTRACT FROM AUTHOR]

A copolymer composed of poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(ethylene glycol) diacrylate (PEGDA) (PHEMA-PEGDA) is structurally versatile. Its structure can be adjusted using the following porogens: water, sucrose, and benzyl alcohol. Using phase separation technique, a variety of surface architectures and pore morphologies were developed by adjusting porogen volume and type. The water and sucrose porogens were effective in creating porous and cytocompatible PHEMA-PEGDA scaffolds. When coated with collagen, the PHEMA-PEGDA scaffolds accommodated cell migration. The PHEMA-PEGDA scaffolds are easy to produce, non-toxic, and mechanically stable enough to resist fracture during routine handling. The PHEMA-PEGDA structures presented in this study may expedite the current research effort to engineer tissue scaffolds that provide both structural stability and biological activity. [ABSTRACT FROM AUTHOR]

We report the observation of room temperature ferromagnetism in Cu-doped (5%) ZnO films grown on c-plane sapphire substrates. Films were prepared by pulsed laser deposition technique and were thoroughly characterized using several state-of-the-art characterization techniques. Hall measurements showed that the films are of n-type with a carrier concentration of 3×1017 cm-3. Magnetization measurements showed that the films exhibit room temperature ferromagnetism with a saturation magnetization of ∼1.45μB/Cu atom. When additional carriers were introduced in the films, ferromagnetism was completely vanished. Our results show that the p-type nature of the film is not essential for realizing ferromagnetic characteristics; however, the concentration of n-type carriers should not exceed a critical value. [ABSTRACT FROM AUTHOR]