There are several ways to nanostructure Si. Some of them, e.g. nanoscale Si-layerd systems buried within the n+ layer of a crystalline Si can provide an initial material with unpredicted optoelectronic behavior. Such a transformation leads to a PV Si metamaterial, whose optoelectronic properties arise from qualitatively new response functions that are (i) not observed in the constituent materials and (ii) result from the inclusion of artificially fabricated, intrinsic and extrinsic, low-dimensional components. We show that an extremely strong c-Si:P absorptance, is larger than can result from conventional conversion because the surface population increases by injection of additional carriers from a nanostratum (transformed up to a Si-metamaterial) lying just behind the top c-Si:P-layer.

Vertically-aligned multiwalled carbon nanotubes (VA-MWCNTs) were grown using plasma enhanced chemical vapor deposition (PECVD) technique. These VA-MWCNTs were then dip coated by Poly methyl methacrylate (PMMA) followed by annealing. Samples were then polished to expose the tips of CNTs. Biological molecules Glucose Oxidase (GOx) were then immobilized on the exposed tips of these nanoelectrode ensembles. Here we present further characterization of these devices, with results on the detection limits and measurement stability. We found that these sensors can be reused for longer than eight months when kept in proper storage conditions.

We investigated the interactions of water soluble single-walled carbon nanotubes (SWNT) with unicellular organisms, in particular a ciliated protozoan (Tetrahymena thermophila) and a bacteria (Escherichia coli), which are common constituents of natural fresh water. The ciliates could effectively incorporate SWNT into natural organic matter (NOM), and therefore into normal ecological processes. Further, SWNT induced the ciliates to egest viable bacteria in membrane-enclosed vesicles. The egested bacteria aggregates had escaped digestion by the protozoan and were able to proliferate and resist antibiotic/disinfectant treatments, which may have important implications to public health. This work highlights the importance of studies on nanoparticle ecotoxicology.

Fuels for advanced nuclear reactors differ from conventional light water reactor fuels and also vary widely because of the specific architectures and intended missions of the reactor systems proposed to deploy them. Functional requirements of all fuel designs for advanced nuclear energy systems include (1) retention of fission products and fuel nuclides, (2) dimensional stability, and (3) maintenance of a geometry that can be cooled. In all cases, anticipated fuel performance is the limiting factor in reactor system design, and cumulative effects of increased utilization and increased exposure to inservice environments degrade fuel performance. In this article, the current status of each fuel system is reviewed, and technical challenges confronting the implementation of each fuel in the context of the entire advanced reactor fuel cycle (fabrication, reactor performance, recycle) are discussed.

The surface of freshly etched silicon nanoparticles (Si-NPs) was covalently bonded with alkyl groups and esters via thermally induced hydrosilylation. The surface chemistry of functionalized Si-NPs was analyzed at different air exposure time by means of Fourier transform infrared spectroscopy (FTIR). We observed that the stability of functionalized Si-NPs significantly depends on the type of organic ligands attached to their surface. Ester-terminated Si-NPs exhibit higher stability compared to that are bonded with alkyl groups. We show that the use of esters with large spatial configuration causes a lower surface coverage of Si-NPs but at the same time offers better protection against surface oxidation.

Purified carbon nanotubes (with removed toxic catalytic particles) have been considered as novel materials for drug delivery and for generating artificial organs more efficiently than traditional tissue engineering materials due to their unique surface features. The surface chemistry of carbon nanotubes has been modified through various functionalization strategies to increase biocompatibility. Importantly, modulating the intrinsic material surface energy of carbon nanotubes (without functionalization, thus, establishing permanent, non degradable chemical, and physical surface properties) can potentially reduce an immune response mediated by macrophages. Herein, we report macrophage responses on different surface energy carbon nanotubes while keeping their nanoscale surface roughness. Specifically, interactions of ultra hydrophobic (bare or unmodified) and hydrophilic carbon nanotubes (due to the formation of oxide layers) with macrophages were investigated. It was observed that macrophage density on both carbon nanotube scaffolds were lower than on traditional materials. In particular, the amount of released cytokine (TNF-α) from macrophages cultured on hydrophilic carbon nanotube scaffolds was much smaller than on hydrophobic carbon nanotube scaffolds. All results clearly supported that tailoring the surface energy of carbon nanotubes mediates a macrophage immune response.

We demonstrate how data mining techniques can be applied to complex combinatorial data sets and how data from multiple sources can be aggregated via the developed scientific data management system. An example is shown for the case of aggregated combinatorial data for the study of composition, processing, structure, and property relationships of transparent conducting oxides by applying data mining techniques such as principal component analysis. Data mappings of mined results are shown to effectively enable visualization of data trends, identification of anomalies in Fourier transform infrared spectroscopy patterns, and scientifically interesting libraries and spectral regions.

A heat pipe is a device that transports heat against gravity using a wicking material and evaporation-condensation cycle..In these systems a thermal wick moves fluid from the cool region of a heat pipe to the hot region, where evaporative cooling occurs. Due to the operating demands of a thermal wick, several microstructural features are integral to the performance of the wick: capillary radii, specific surface area and permeability. Measuring these properties of a thermal wick (capillary radii, specific surface area and permeability) is difficult, therefore image analysis methods of quantification of the critical properties of a thermal wick has been developed . However, the microstructure of a thermal wick contains semicontinuous pores, therefore connectivity of pores cannot be assumed during quantification of the critical properties.. Two processing parameters, sacrificial template particle size and sintering temperature, were varied during the thermal wick synthesis. Quantification of the critical properties of the thermal wick was performed using the newly developed method. The newly developed method was able to detect the an increase in the pore connectivity as the sintering temperature decreased, and an increase in the connectivity as the sacrificial template particle size decreased. The newly developed method was also able to describe the size distribution of individual pores as well as the hydraulic resistance and orientation of individual pores as well as estimate the porosity and true specific surface area of the different samples.

We present result following localized ion implantation of rutile titanium dioxide (TiO2) using anodic porous alumina as a mask. The implantation were performed with 100 keV 56Fe+ ions using a fluence of 1.3·1016 ions/cm2. The surface modifications where studied by means of SEM, AFM/MFM and XRD. A well-defined hexagonal pattern of modified material in the near surface structure is observed. Local examination of the implanted areas revealed no clear magnetic signal. However, a variation in mechanical and electrostatic behavior between implanted and non-implanted zones is inferred from the variation in AFM signals.

Since the invention of organic electroluminescent devices, a great deal of effort has been made to improve their performance. Reducing the barrier and optimizing charge injection is crucial for efficient and bright Organic Light Emitting Diodes (OLEDs). We report the performance of OLEDs with ITO/TPD/Alq3/Al structure by inserting LiF both at electrode-organic interfaces and organic-organic interface. We elucidate the mechanism of the LiF buffer layer inserted at different interfaces. The device with LiF as a cathode injection layer shows improved luminescence and steeper IV characteristics.

Various bone defects, caused by trauma, disease or age-related degeneration, represent a crucial clinical problem all over the world. However, traditional implant materials may cause many complications after surgeries, leading to intense patient pain. Thus, the objective of this in vitro study was to develop a biologically inspired coating on conventional titanium with materials that possess biomimetic nanostructured architectures and favorable surface chemistry. Specifically, self-assembled rosette nanotubes (RNTs) functionalized with various osteogenic peptides and amino acids (such as lysine-arginine-serine-arginine (KRSR), arginine-glycine-aspartic acid (RGD) and lysine (K)) were designed as coatings. Results revealed excellent cytocompatibility properties of these RNTs towards enhancing osteoblast (bone forming cell) and endothelial cell adhesion. In particular, KRSR and RGD functionalized RNTs coated on titanium promoted the greatest osteoblast densities when compared to uncoated titanium. In addition, the KRSR functionalized RNTs selectively improved osteoblast adhesion but not endothelial cell adhesion when coated on titanium. From this study, it can be speculated that the biologically inspired nanotubular structure and osteogenic surface chemistry of RNTs altered the surface properties of titanium to transform it into a more favorable environment for orthopedic applications.

Aluminum oxide (Al2Ox) buffer layers were employed to grow single-walled carbon nanotubes (SWNTs) at 400°C using an alcohol gas source and a Co catalyst. By optimizing the thickness of the aluminum oxide layer, the SWNT yield was enhanced by a factor of several times. In addition, SWNT growth at 350°C was realized on the Al2Ox buffer layer by this method. Raman measurements at various excitation wavelengths suggest that a Al2Ox buffer layer preferentially enhances the growth of SWNTs with larger diameters (>1 nm).

This paper uses complex magnetic susceptibility measurements to investigate the effects of different coatings on the susceptibility of iron oxide nanoparticles. The two coatings used in these measurements are aminosilane and carboxymethyl-dextran. Susceptibility measurements are carried out over a range of frequencies from 10 KHz to 1 MHz using a differential impedance method. The differential impedance measurement setup is validated by measuring the susceptibility of ferrofluids and comparing the results to values previously published in literature. The theoretical relaxation times based on Brownian and Neel mechanisms are used to predict the resonance frequency of imaginary part of complex susceptibility for iron oxide nanoparticles.

Trapping in low-κ dielectric for interconnects was highlighted by voltage shift in IV current-voltage measurements. It is shown that effects of trapping can impact the extraction of conduction mechanisms. Capacitance measurements made on these materials reveal that trapping is at the origin in the increase of capacitance. The creation of dipoles because of this trapping explains this increase in the value of capacitance.

Drop on demand inkjet printing is a potential method for depositing enzymes onto electrodes for sensor applications. This technology offers drop sizes in the region of picolitres and allows a production rate up to 200 mm/s. This enables not only a more rapid method of device prototyping but also a method for possible miniaturization of the sensors themselves. However, previous work [1] has indicated that inkjet printing may cause a drop in the retained activity of the enzyme.

Here we assess the criticality of this drop in activity and how it may have been influenced by changes to the protein structure during printing. The enzyme used is glucose oxidase and the test methods include; protein analysis, in the form of analytical ultra-centrifugation and circular dichroism, scanning electron microscopy, atomic force microscopy and phase contrast microscopy, to analyse the surface topology of the electrodes and contact angle analysis, to assess the degree of spreading and the interactions between the drops and the electrode surface.

With glucose oxidase there is no change in the conformation, structure or hydrodynamic radius of the protein after printing. The analysis of the electrode surface shows a relatively smooth surface that is made up of individual graphite flakes laid down by a screen printing method. When contact angle and spreading analysis is carried out it demonstrates reliability in the printing process as well as a drop in the sessile volume of the drop in conjunction with a growth in the base diameter of the drop as expected. It also demonstrates a fairly quick rate of evaporation of the drop. Upon the addition of surfactants to the solution the spreading is seen to be more extensive in relation to the surfactant concentration, although some initial reduction in experienced at low concentrations which may be due to the absorption into the carbon surface.

Despite research efforts to find a better nano-optical transducer for light localization and high transmission efficiency for existing and emerging plasmonic applications, there has not been much consideration on improving the near-field optical performance of the system by engineering the near-field sample. In this work, we demonstrate the impact of tailoring the near-field sample by studying an emerging plasmonic application, namely heat-assisted magnetic recording. Basic principles of Maxwell's and heat transfer equations are utilized to obtain a magnetic medium with superior optical and thermal performance compared to a conventional magnetic medium.

N-polar and Ga-polar GaN grown on c-plane sapphire by a metal-organic chemical vapor deposition (MOCVD) system were used to fabricate platinum deposited Schottky contacts for hydrogen sensing at room temperature. Wurtzite GaN is a polar material. Along the c-axis, there are N-face (N-polar) or Ga-face (Ga-polar) orientations on the GaN surface. The Ohmic contacts were formed by lift-off of e-beam deposited Ti (200 Å)/Al (1000 Å)/Ni (400 Å)/Au (1200 Å). The contacts were annealed at 850°C for 45 s under a flowing N2 ambient. Isolation was achieved with 2000 Å plasma enhanced chemical vapor deposited SiNx formed at 300°C. A 100 Å of Pt was deposited by e-beam evaporation to form Schottky contacts. After exposure to hydrogen, Ga-polar GaN Schottky showed 10% of current change, while the N-polar GaN Schottky contacts became fully Ohmic. The N-polar GaN Schottky diodes showed stronger and faster response to 4% hydrogen than that of Ga-polar GaN Schottky diodes. The abrupt current increase from N-polar GaN Schottky exposure to hydrogen was attributed to the high reactivity of the N-face surface termination. The surface termination dominates the sensitivity and response time of the hydrogen sensors made of GaN Schottky diodes. Current-voltage characteristics and the real-time detection of the sensor for hydrogen were investigated. These results demonstrate that the surface termination is crucial in the performance of hydrogen sensors made of GaN Schottky diodes.

Hybrid organic-inorganic nanocomposite silica with surfactant � cetylpyridinium chloride with the polyphase structure, having a high electrorheological activity, is synthesized using sol-gel method. Physical-mechanical characteristics of dispersions based on mineral oil and synthesized powder with the concentration of 20 and 30 % by weight are investigated. The results of the shear stress measurements versus the strength of the dc and ac (frequency 50 Hz) electric fields (0 � 3.5 kV/mm) at Couette shear (shear rate 8 � 390 s) and yield stress in the range of temperatures 20 � 97 �C are presented. The comparative analysis of the results obtained with the results for the powder of the hybrid organic-inorganic nanocomposite silica/ polyethylene glycol is carried out.

We report selective area epitaxy of InGaN/GaN micron-scale stripes and rings on patterned (0001) AlN/sapphire. The objective is to elevate indium incorporation for achieving blue and green emission on semi-polar crystal facets. In each case, GaN structures were first produced, and the InGaN quantum wells (QWs) were subsequently grown. The pyramidal InGaN/GaN stripe along the <11-20> direction has uniform CL emission at 500 nm on the smooth {1-101} sidewall and at 550 nm on the narrow ridge. In InGaN/GaN triangular rings, the structures reveal smooth inner and outer sidewall facets falling into a single type of {1-101} planes. All these {1-101} sidewall facets demonstrate similar CL spectra which appear to be the superposition of two peaks at positions 500 nm and 460 nm. Spatially matched striations are observed in the CL intensity images and surface morphologies of the {1-101} sidewall facets. InGaN/GaN hexagonal rings are comprised of {11-22} and {21-33} facets on inner sidewalls, and {1-101} facets on outer sidewalls. Distinct CL spectra with peak wavelengths as long as 500 nm are observed for these diverse sidewall facets of the hexagonal rings.