Zinc oxide (ZnO) is a metal-oxide semiconductor that has attracted resurgent interest as an electronic material for a range of device applications. In our work, we have focused on how defect properties change as one goes from the bulk to the nanoscale. Infrared (IR) reflectance spectra of as-grown and hydrogen-annealed ZnO nanoparticles were measured at near-normal incidence. The as-grown particles were electrically semi-insulating, and show reflectance spectra characteristic of insulating ionic crystals. Samples annealed in hydrogen showed a significant increase in electrical conductivity and free-carrier absorption. A difference was observed in the reststrahlen line shape of the conductive sample compared to that of the as-grown sample. In addition to hydrogen doping, we successfully doped ZnO nanoparticles with Cu. To probe the electronic transitions of Cu2+ impurities in ZnO nanoparticles, IR transmission spectra were taken at liquid-helium temperatures. Two absorption peaks were observed at energies of 5781 and 5821 cm-1. Finally, we tentatively assign a series of IR spectral lines to Na acceptors.

The interaction of photons with metallic nanoparticles and nanoantennas yields large enhancement and tight localization of electromagnetic fields in the vicinity of nanoparticles. In the first part of this study, the interaction of a spherical nanoparticle with focused beams of various angular spectra is investigated. This study demonstrates that the focused light can be utilized to manipulate the near-field radiation around nanoparticles. In the second part of this study, the interaction between linearly and radially polarized focused light with prolate spheroidal nanoparticles and nano-antennas is investigated. Strong and tightly localized longitudinal components of a radially polarized focused beam can excite strong plasmon modes on elongated nanoparticles such as prolate spheroids. The effect of a focused beam on parameters such as the numerical aperture of a beam and the wavelength of incident light, as well as particle geometry and composition are also studied.

Coupled quantum dots (CQDs) can provide a sensitive probe of the electric field within a device. With non-resonant excitation above the wetting layer (WL) energy, optical generation of an electric field within the CQD structure was observed. By alternating this non-resonant excitation the temporal response of the optically generated electric field was measured. Decay of this field was measured to be on the order of 110-140 μsec whereas the onset of the optically generated electric field was observed to be less than the temporal resolution of our experiment (7.5 μsec). This may provide a means for fast, non-contact, electric field modulation techniques.

Recently, size effects in the initiation of plasticity have been clearly observed and reported in different geometries; e.g., bending (Ehrler et al. Phil. Mag. 2008), twisting (Ehrler et al., MRS, Spring Meeting 2009) and indentation (Zhu et al. J. Mech. Phys. Sol. 56, 1170, 2008). Strain gradient plasticity theory is the principal approach for explaining size effects during plastic deformation in these geometries. However, it fails to account for any size effect at the initial yield. Geometrical critical thickness theory was proposed to explain the yield size effect in bending and torsion (Dunstan and Bushby, Proc. Roy. Soc. A460, 2781, 2004). The theory shows that the initial yield strength is scaled with the inverse square root of the characteristic length scale without requiring any free fitting parameters. Here, we extend the theory to describe the yield size effect in indentation. The theory agrees fairly well with experimental observations in micro-torsion (Ehrler et al., MRS, Spring Meeting 2009) and nanoindentation (Zhu et al., J. Mech. Phys. Solid, 2008).

We analyze the grain size distribution during solid phase crystallization of Silicon thin films. We use a model developed recently that offers analytical expressions for the time-evolution of the grain size distribution during crystallization of a d-dimensional solid. Contrary to the usual fit of the experimental results with a lognormal distribution, the theory describes the data from basic physical principles such as nucleation and growth processes. The theory allows for a good description of the grain size distribution except for early stages of crystallization. The latter case is expected and discussed. An important outcome of the model is that the distribution at full crystallization is determined by the time-dependence of the nucleation and growth rates of grains. In the case under consideration, the theory leads to an analytical expression that has the form of a lognormal-type distribution for the fully crystallized sample.

Density functional theory was used to investigate the adsorption and reaction of HfCl4 with two hydroxyls on Si (001)-2×1 surface in atomic layer deposition (ALD) process. When H2O molecules are adsorbed on Si (001) surface at room temperature, they are dissociated with hydrogens and hydroxyls. There are two dissociation pathways; inter-dimer dissociation and intra-dimer dissociation. The activation energies of these pathways can be converted to the reaction probabilities. It was approximately 2:1. We prepared a reasonable Si substrate which consisted of six inter-dimer dissociated H2O molecules and two intra-dimer dissociated H2O molecules. The HfCl4 must react with two hydroxyls to be a bulk-like structure. There were five reaction pathways where HfCl4 could react with two hydroxyls; inter-dimer, intra-dimer, cross-dimer, inter-row, and cross-row. Inter-row, inter-dimer and intra-dimer were relatively stable among the five reaction pathways based on the energy difference. The electron densities between O and Hf in these three reactions were higher than the others and they had shorter Hf-O and O-O bond lengths than the other two reaction pathways.

Instrumented indentation testing (IIT) is a very useful technology for the mechanical characterization of materials. However, existing IIT techniques, which are based on the Hertz model and were developed for hard materials with negligible surface adhesion such as metals and ceramics, are difficult to directly apply to compliant materials such as elastomeric polymers which have viscoelastic hysteresis due to infinitesimal surface/interfacial adhesion. Here we employed some modified model to evaluate the work of adhesion in elastomeric polymer from our previous work, and reinforced our theory and algorithm through empirical approaches so as to consider the time-dependency of viscoelastic material as testing parameter. To do these all, we combined analytic JKR theory and conventional IIT technology to analyze the physical meaning of the theory and then verified our ideas experimentally with elastomeric polymer, PDMS (poly(dimethyl-siloxane)), of various compositions. Our algorithm was developed and verified on a microinstrumented indentation basis and extended even into the nanoinstrumented testing for the micro/nano-scaled applications.

To gain basic insight into the impact of non-biological features on cells’ behaviour, primary skin-cells, keratinocytes and fibroblasts, were cultured on amine-functionalized or carboxy-functionalized planar, nano- or microstructured surfaces. Sintered layers of silica nano- or microparticles were used to fabricate structures in the range of naturally occurring structure-sizes. Organo-chemical functionalization was achieved using organo-functional silanes. Primary human keratinocytes and fibroblasts were isolated from human foreskin and cultivated on the modified interfaces. Both cell-types displayed specific proliferation behaviour, depending on surface topography and chemical functionalization: Keratinocytes showed significantly better proliferation on amino-functionalized surfaces than on carboxy-functionalized surfaces. On amino-functional surfaces decree-topography. Fibroblasts, in contrast, tended to proliferate stronger on carboxylated surfaces. Immunohistological staining proofed that actin and vinculin, which is involved in the formation of focal adhesions, were expressed on all modified surfaces, thus revealing intact cytoskeleton and cell-substrate contacts.

Processes of biodegradable molded products were developed. However, to make commercial products to adapted each purpose is still under going. So, this time, to improve the molded products properties, we tested to blend with PLA (polylactic acid) or PBSA (Poly butylenes succinate adipate) into CGM(Corn gluten meal) based agro by-products ingredient.

Molded samples were able to make from all tested material and each sample had each physical properties. Finally, we selected suitable condition for practical field test of Large Sapling Pot for Persimmon saplings. Such application will be addressed in our talk and general situation of biodegradable products by biomass resources in Japan will be also introduced.

Previously, the nanocrystalline grain boundaries were often contaminated by the “non-diamond phase” with the photo-ionization threshold at 0.8 eV. Here, we present the optical spectra of the NCD films grown on transparent substrates by the microwave plasma enhanced chemical vapor deposition (CVD) at a relatively low temperature below 600°C. The transmittance and reflectance spectra are useful to evaluate the film thickness, the surface roughness and the index of refraction. The direct measurement of the optical absorptance by the laser calorimetry and photothermal deflection spectroscopy (PDS) provides high sensitive methods to measure the weak optical absorption of thin films with rough surface. The optical measurements indicate the high optical transparency of our standard, nominally undoped 0.2-0.3 μm thick NCD film with low non-diamond content. However, the optical scattering is rather high in UV and needs to be reduced.

Spatial-frequency transfer functions are regularly used to model the imaging performance of near-field �superlens� systems. However, these do not account for interactions between the object that is being imaged and the superlens itself. As the imaging in these systems is in the near field, such interactions are important to consider if accurate performance estimates are to be obtained. We present here a simple analytical modification that can be made to the transfer function to account for near-field interactions for objects consisting of small apertures in otherwise-continuous metal screens. The modified transfer functions are evaluated by comparison with full-field finite-element simulations for representative single-layer and multi-layer silver superlenses, and good agreement is found.

Miniaturized and highly sensitive bio-sensors are attractive in various applications, such as medicine or food safety. Photonic crystal (PhC) microcavities present multiple advantages for rapid and accurate label-free optical detection. But their principle of operation (i.e. observation of a peak in transmission) makes their integration in serial arrays difficult. We present in this paper a multi-channel sensor consisting of several resonant PhC microcavities coupled to the same waveguide. The transmission spectrum shows as many dips as there are cavities, and each of the microcavities can act as an independent sensor. Preliminary results show the fabrication and characterization of a double-channel structure with small defects used as a solvent sensor.

Thermal properties of five divalent ruthenium precursors with three types of structures were examined by thermal analyses. Their volatilities and the relationships between their structure and thermal stability were compared by TG analysis. Precursor volatility was found to be inversely proportional to molecular weight. The DSC result showed that substituting a linear pentadienyl ligand for a cyclopentadienyl ligand decreased the thermal stability of a precursor and precursors could be liquefied by attaching an alkyl group longer than methyl group to a Cp ligand. As a result of TG-MS analyses for Ru(DMPD)(EtCp) and Ru(EtCp)2, 2,4-dimethyl-1,3-pentadiene was found to be a thermolysis product of Ru(DMPD)(EtCp) though no thermolysis products of Ru(EtCp)2 were observed. These results show that the volatility and decomposition temperature of a divalent ruthenium precursor can be designed by adjusting the precursor's structure.

Alloying has been one of the strategies to develop alternatives to Pt based CO oxidation catalyst. PdAu bimetallic alloy has recently been shown to have better reactivity and thermal stability toward CO oxidation for diesel engine applications as compared to pure metal catalysts. The key factor for low temperature light off in diesel engine catalysis is reactivity of alloy catalysts under CO environment, which in turn depends on the alloy surface composition and morphology. We explored the segregation processes in bimetallic Pd-Au alloy using first-principles calculations, assisted by a Monte-Carlo (MC) scheme that combines an improved Embedded Atom Method (EAM) and an atomistic treatment for adsorbed CO molecules for searching low energy states. Our simulation results show that PdAu surface changes from Au-rich to Pd-rich with increase in CO coverage up to 0.75 ML, beyond which additional CO adsorption is no longer favorable. A quantitative relationship between CO coverage and Pd concentrations on the surface is also revealed.

With the rapid change of materials systems and decreased feature size, thin film microstructure and mechanical properties have become critical parameters for microelectronics reliability. An example of a major driver of this new technology is the data storage community who is pushing for 1 Terabit/square inch on its magnetic disk hard drives. This requires inherent knowledge of the mechanical properties of materials and in depth understanding of the tribological phenomena involved in the manufacturing process. Chemical mechanical polishing (CMP) is a semi-conductor manufacturing process used to remove or planarize ultra-thin metallic, dielectric, or barrier films (copper) on silicon wafers. The material removal rate (MRR), which ultimately effects the surface topography, corresponding to CMP is given by the standard Preston Equation, which contains the load applied, the velocity of the pad, the Preston coefficient which includes chemical dependencies, and the hardness of the material. Typically the hardness, a bulk material constant, is taken as a constant throughout the wafer and thereby included in the Preston coefficient. Through metallurgy studies, on the micro and nano scale, it has been proven that the hardness is dependent upon grain size and orientation. This research served to first relate the crystallographic orientation to a specific hardness value and secondly use the hardness variation in the previously developed particle augmented mixed-lubrication (PAML) model to simulate the surface topography and MRR during CMP. Recent test and results show that currently there is no empirical formula to relate the crystallographic orientation and thereby a critically resolved shear stress (CRSS) to a specific hardness value. The second part of this investigation utilized the variation in hardness values from the initial study and incorporated these results into the PAML numerical model that incorporates all the physics of chemical mechanical polishing (CMP). Incorporation of the variation of hardness resulted in a surface topography with a difference in roughness (Ra) from the bulk constant hardness value of 60 nm. The material removal rate (MRR) of the process differs by 2.17 μm3/s.

Nanotechnology has the potential to greatly improve our lives through medical, environmental and consumer products. Properties at the nanoscale are being exploited in new products, but they could also influence how the particles interact with humans and the environment. There is increasing consensus that for nanotechnology to reach its maximum potential, we must work to understand the hazards and exposure routes in order to minimise the risks. Good practice, founded on the principles of risk assessment and industrial hygiene, are applicable to a wide range of nanomaterials and nanostructured materials including nanoparticles, nanofibres, nanopowders, nanotubes, as well as aggregates and agglomerates of these materials. There is still considerable uncertainty about many aspects of effective risk assessment of nanomaterials, including the hazardous potential of many types of nanoparticles and the levels below which individuals might be exposed, with minimal likelihood of adverse health effects. It is prudent therefore to understand how to develop an appropriate strategy for the risk assessment, handling and disposing of nanomaterials, in the light of known and unknown hazards and exposures. This paper presents a perspective of the key components of risk assessment applicable to nanotechnology and novel materials.

A new class of porous membrane has been fabricated that is unique in its combination of nanoscale thickness (<50 nm) with macroscopic, yet robust, millimeter-scale lateral dimensions and tunable pore size in the range of ˜5nm to ˜100nm. The membrane material is porous nanocrystalline Si (pnc-Si)1, and is being scaled-up to commercial volumes by a startup company, SiMPore, Inc. Standard commercial separation membranes with pores in this size regime are polymeric materials (poly ether sulphone, cellulose, etc.), microns in thickness, leading to pore morphologies that resemble long narrow tubes or tortuous-path 3-D matrices. As pnc-Si membrane thickness approaches the pore diameters, a simplified structure of holes in a thin sheet results, greatly enhancing both diffusive and forced flow transport through the membrane, as predicted by classical transport theories2. Pnc-Si has confirmed these theoretical predictions, demonstrating record-breaking transport rates, in addition to precise size-separation of nanoparticles, viruses, proteins, and nucleic acids.Applications for this highly precise silicon-based membrane range from highly efficient separations and purification of biomolecules, complexes, and nanoparticles, to substrates for microscopy to cell culture and co-culture. SiMPore is focused on navigating this application space with the goal of quickly introducing products that will allow the company to become self-sustaining and profitable though direct sales or partnerships with market leaders. Key product development drivers include potential competitive performance advantages and perceived value to a particular market, the IP landscape, development costs of the membrane and the device package/interface, and alignment with existing in-house capabilities.

Polymer networks synthesized by UV-curing of Oligo[(ε-caprolactone)-co-glycolide]dimethacrylates are hydolytically degradable. Their architecture with covalent netpoints and crystallizable domains is the molecular basis for the potential shape-memory capability. The molecular weight and glycolide content of the oligomeric precursors can be varied over a broad range of compositions to tailor the thermomechanical properties of the polymer network while having only a minor influence on the shape-memory effect. Recently, drug incorporation adding controlled drug release as further functionality to the polymer network was demonstrated [4]. Here, enoxacin and ethacridine lactate as test drugs were incorporated into the networks by soaking. Alternatively, defined amounts of ethacridine lactate were mixed with the precursors, which were subsequently crosslinked to the drug containing networks. The composition of the oligomeric precursors in molecular weight between 3800 and 12800 g�mol-1 and in glycolide content ϝG between 0 and 30 mol-% to explore the influence of the drug incorporation on networks with varying compositions while retaining properties and functionalities. Polymer networks prepared from precursors with ϝG ? 14 mol-% and Mn ? 6900 g�mol-1 have a Tsw of 35-52 �C and sufficient crystallinity to ensure a high shape fixity in the programming step. These limits have to be kept to ensure the desired multifunctionality, otherwise drug incorporation can have an undesired influence on thermal, mechanical, and shape-memory properties.

Studying how individual neuronal cells grow and interact with each other is of fundamental importance for understanding the functions of the nervous system. However, the mechanism of axonal navigation to their target region and their specific interactions with guidance factors such as membrane-bound proteins, chemical and temperature gradients, mechanical guidance cues, etc. are not well understood. Here we describe a new approach for controlling the adhesion, growth and interconnectivity of cortical neurons on Au surfaces. Specifically, we use Atomic Force Microscopy (AFM) nanolithography to immobilize growth-factor proteins at well-defined locations on Au surfaces. These surface-immobilized proteins act as a) adhesion proteins for neuronal cells (i.e. well-defined locations where the cells “stick” to the surface), and b) promoters/inhibitors for the growth of neurites. Our results show that protein patterns can be used to confine neuronal cells and to control their growth and interconnectivity on Au surfaces. We also show that AFM nanolithography presents unique advantages for this type of work, such as high degree of control over location and shape of the protein patterns, and application of proteins in aqueous solutions (protein buffers), such that the proteins are very likely to retain their folding conformation/bioactivity.

Light impinging upon electrospun nanofiber substrates encounters a complex media where a multitude of factors controls the transmittance and reflectance of light through the structure. The chemical composition of the nanofiber plays a significant role in that it determines the index of refraction of individual fibers. However, the surrounding media (e.g., air, encapsulating polymer, etc.) also plays an equally important role. In addition, physical effects such as fiber diameter, fiber morphology, fiber packing density (i.e., structure void volume), and substrate thickness play a large role in determining the light management properties of nanofibers. Our research has demonstrated that the transmittance and reflectance of undoped nanofibers can be adjusted through proper manipulation of these factors. For example, similar electrospinning formulations can produce either highly transmitting or highly reflecting light structures depending upon fabrication parameters that impact the final properties of the nanofiber substrates. In addition, a degree of wavelength dependent reflectance and transmittance can be imparted simply by adjusting the physical properties of the nanofibers to promote preferential light scattering below selected frequencies.This paper provides an overview of various factors impacting the light management properties of nanofiber substrates and the importance of controlling these factors to meet end-use applications.