In this paper, we report on a method for fabricating an inexpensive microfluidic platform on parchment paper. Parchment paper was selected for this purpose due to its wide availability for culinary applications and hydrophobic silicone-based surface coating. We were able to selectively modify the surface structure and property (hydrophobic to hydrophilic) using a CO2 laser. The modified surface has highly-porous structure which helps to trap chemical and biological reagents for analysis. The treated surface is stable over time and can be used for aqueous droplet assembly. Finally, we demonstrated the applicability of this platform for performing chemical reaction using luminol-based hemoglobin detection.

It is now possible to create perfect crystal nanowires of many metals. The deformation of such objects requires a good understanding of the processes involved in plasticity at the nanoscale. Isotropic compression of such nanometre scale micropillars is a good model system to understand the plasticity. Here we investigate these phenomena using Molecular Dynamics (MD) simulations of nanometre scale single crystal BCC iron pillars in compression.

We find that pillars with large length to width ratio may buckle under high strain rates. The type of buckling behaviour depends sensitively on the boundary conditions used: periodic boundary conditions allow for rotation at top and bottom of the pillar, and result in an S shaped buckle, by contrast fixed boundaries enforce a C shape. Pillars with a length to width ratio closer to that used in experimental micropillar compression studies show deformation behaviour dominated by slip, in agreement with the experiments. For micropillars oriented along <100>, slip occurs on <110> planes and localized slip bands are formed. Pillars of this size experience higher stresses than bulk materials before yielding takes place. One might expect that this may be in part due to the lack of nucleation sites needed to induce slip. However, further simulations with possible dislocation sources: a shorter iron pillar containing a spherical grain boundary, and a similar pillar containing jagged edges did not show a decreased yield strength.

We presented in this paper a photo-assisted ligand exchange approach wherebylight will be introduced to facilitate the replacement of oleic acid (OA)ligand molecules over PbSe quantum dots (QDs). The ligand-exchanged QDs wereused to fabricate quantum dot light-emitting-diodes (QD-LEDs), whichoutperform the devices comprising the QDs without ligand-replacement.

Photobacterium kishitanii is one species of luminescent bacteria. This bacterium is known to convert chemical energy into light; it glows in the dark with a visible peak wavelength (ca. 475 nm) that is easily recognized. Luminescent bacteria produce autoinducers and respond to this molecule to switch on the luciferase structural operon. Luminescence is, therefore, controlled by the cell-population density.

If bacterial cells are viewed as enzyme bags, substrates, such as oxygen or autoinducers, diffuse into the bags through a semipermeable cell wall and are catalyzed by the enzyme. Oscillation in the product concentration is often observed in systems where a semipermeable membrane separates the substrate and the enzyme. Such behavior is simulated using a reaction-diffusion model.

We have reported several characteristics of the luminescence from a bacterial suspension. For example, in a batch culture, higher initial bacteria density resulted in an earlier luminescence starting time [1]. Apart from such linear characteristics, we have reported an oscillation in the luminescence intensity both spatially and temporally [2]. We hypothesize that a group of bacteria behaves differently from a sum of single cells. The nonlinearity of the bacterial luminescence might be a key to understanding the phenomenon. In a previous experiment, we separated bacteria into small groups that showed similar characteristics, such as motility and adsorption activity. For example, bacteria separated according to their motility using a microfluidic device were proved to show different bioluminescent intensities for each cell [3]. On an agar plate, the luminescence intensity from actively dividing cells was less than that from mature cells [4]. In addition to this basic study to understand the oscillation in bacterial luminescence, reactors were designed to realize stable bacterial luminescence. In a PDMS cell, only the parts of the suspension that faced the wall were illuminated [5]. This result suggested that the geometrical symmetry of oxygen supply to the suspension helped maintain spatial stability without convection of the bacterial luminescence.

Here, we report the luminescence behavior of bacteria that adsorbed on material surfaces. In this work, we show experimentally that the bacteria adsorb on the inner surfaces of a polyethylene terephthalate (PET) or polystyrene (PS) bottle and start to emit light when a liquid broth is added. We also show that the luminescence from the suspension oscillates. Experimentally, using a self-made luminescence detector, measurement of luminescence intensity from well-stirred bacterial suspensions in the bottles of different materials (PVC, PET, or PS) was performed. After the observation of oscillation in luminescence, the bottles were washed three times using the same broth, followed by the luminescence measurement. Such washing and measurements were repeated, and oscillation was repeatedly observed. The chemical condition of adsorption on the surface was investigated using surface analysis methods, such as AFM or FTIR, and the material characteristics with regard to cell adsorption and oscillation mode were discussed.

We have investigated the barrier height for electron injection at thecathode / polyflu-orene derivatives interface by the internal photoemission(IPE) spectroscopy techniques using the “electron only device” structureconsisting of TiO2, electron transporting polyimide inter-layer(IL), and polyfluorene derivatives. We also estimated the barrier height bythe current analysis based on the Schottky thermal emission current model,and it coincides well to the threshold energy of IPE result only when theenergy is lower than 1.1eV. The measured barrier height obtained by IPElinearly increases with both the work-function of cathode materials.However, the slope parameter becomes less than 1 (~0.6) for poly(9,9-dioctylfluorene) (F8) probably due to the interfacial gap states. Onthe other hand, the slope parameter becomes very small (~0.18) for the poly(9,9-dioctylfluorene)-co- benzo- thiadiazole) (F8BT) probably due to theelectron pinning at the cathode/ acceptor interface.

A model to study the formation of compositional patterns in concentrated binary alloys under irradiation is presented. In this model, six atomic and defect species are considered: regular lattice atoms (A and B), dumbbell interstitials (AA, BB and AB) and vacancies. In addition to long range diffusion of these species, local defect-defect (vacancy-interstitial recombination) and defect-atom (dumbbell-atom) reactions have also been considered. The model tracks simultaneous evolution of all the species in reaction-diffusion formalism. Irradiation events are modeled as a stochastic point process which changes the concentration of all the species instantaneously in a random fashion. In each irradiation event, a spatial distribution of point defects (core-shell distribution: core dominated by vacancies and shell by interstitials) has been introduced in the system which drives the kinetics of diffusion and reaction. The model has been non-dimensionalized with respect to intrinsic length and time scales of the material system and solved numerically using finite difference technique. Applying this model to CuAu solid solution, we have shown that the alloy exhibits spinodal-like decomposition with specific steady state wavelengths that depend on the irradiation conditions.

The Dye-sensitized Solar Cell (DSSC) has been regarded as the next-generation solar cell because of its simple and low cost fabrication process. The experiments for optimizing the cell efficiency were carried out in this work include varying the TiO2 layer thickness on the working electrode and determining the most favorable nanoparticle size in the TiO2 paste. The TiO2 electrode or working electrode was fabricated using screen printing technique with the Coatema tool with thicknesses ranging from ~20 to 66 μm. It was observed that both open circuit voltage and short circuit current were found to have measurable dependence on the TiO2 layer thickness. The open circuit voltage changed from 0.77 to 0.82 V and correspondingly the short circuit current also varied from ~19 to 23 mA/cm2 depending on the TiO2 layer thickness. Additionally, the cell with 40 μm TiO2 thickness showed 9.06% photo conversion efficiency compared to 6.4% and 8.5% efficiency obtained for the cells with 20 μm and 66 μm TiO2 thicknesses respectively. The second part of the experiment was conducted using three different nanoparticle sizes of 13 nm, 20 nm and 37nm in the TiO2 layer to identify optimum nanoparticle size by maintaining the TiO2 film thickness at 40 μm. The cell with 20 nm size nanoparticle, in combination with 40 μm TiO2 thickness showed 11.2% efficiency that is in par or slightly better than the efficiency value reported for the DSSC in the literature as of now. The work described in this paper showed best possible values for the TiO2 layer thickness and nanoparticle size in the TiO2 for obtaining improved cell efficiency of 11.2%.

We investigated the electrical characteristics and digital data transmission performance few-layer graphene ribbons grown by chemical vapor deposition. Graphene ribbons having a mobility of 2,180 cm2V-1s-1 can sustain data rates up to 50 megabits per second at 1.5 μm length, thus the bandwidth is inversely proportional to resistance caused by defects in the graphene layers. Improving the graphene mobility to highest measured values (∼200,000 cm2V-1s-1) and using structures with multiple coplanar transmission lines in parallel could carry the bandwidth beyond the gigabits per second level.

TiO2 nanoparticles have been prepared by sol-gel process using titanium isopropoxide as a precursor with ethanol and water as solvents. The synthesis involves gel formation, digestion for 24h, drying at 100oC for 10h, and calcination in air at 500-800oC for 2h. The resulting powder has been studied with respect to phase(s), morphology, optical absorption and photo -luminescence (PL) behaviour. The calcination of dried sol-gel product at 500oC for 2h leads to formation of anatase phase that possesses a tetragonal structure (a = 3.785 Å, c = 9.514 Å, Z = 4), average crystallite size ~ 11 nm and band gap of 3.34 eV. Further, increasing the time (t) of calcination causes crystallite growth that follows the relation d = α – β exp (-t/τ), α = 18.1 nm, β = 9.6 nm and τ = 6.9h. However, calcination of sol-gel product at 800oC for 2h gives rise to a rutile phase (tetragonal a = 4.593Å, c = 2.959Å, Z = 2), average crystallite size ~ 25 nm and band gap of 3.02 eV. The anatase phase exhibits strong PL emission peaks (excitation wavelength 405 nm) at 2.06 and 1.99 eV due to defect levels within the energy band gap. This observation has been attributed to finite size effects occurring in nanoparticles.

An innovative “Rapid-Solidification Centrifugal Casting (RSCC) Process” was applied to manufacturing more high functional Fe-based magnetic alloys and some amorphous bulk metallic glassy alloys (BMGs) components. The molten alloys were poured into copper mold with rotation speed up to 6000rpm which can cause the maximum 4000 times as much centrifugal pressurization force as gravity. The bulk components of ring or very small three dimensional component samples of Fe and Zr alloy systems were successfully fabricated within only a few seconds at one process from melts with more cheap production cost. The molten raw BMG alloys (ZrAl system) and Fe-based soft-magnetic alloys(FeGaAl and FeSiB systems) by high frequency induction heating method were poured into copper mold. The fabricated BMG components of artificial tooth and ring of ZrAlNiCu alloy system are almost amorphous state by XRD profiles. Especially, the soft magnetic properties of two Fe-based alloys showed drastic change and were enhanced generally depending on the unique very fine, nano-scale columnar grains with strong texture toward radius direction for FeGaAl(Galfenol) alloy. The magnetization saturation Bs was enhanced up to1.97T in FeSiBPCu alloy. In consequence, according to synergistic effect of rapid solidification and high pressurization casting in this manufacturing process, RSCCP has the technical advantages of expansion of element composition, uniformity of the quality, reduction of internal defects and prevention of degradation at the time of secondary fabrication process of nano-crystalline-structured alloys and BMGs.

Inorganic-organic nanocomposites, with II-VI or III-V semiconductor nanocrystals (NCs) embedded in semiconducting polymer matrix, are very promising materials for photovoltaic applications.

Here, we present an effective and easy synthesis procedure to obtain a hybrid nanocomposite with CdS NCs dispersed in poly[2-methoxy-5-(2-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) conjugated polymer. CdS NCs are synthesized directly within the matrix through the decomposition of a suitable unimolecular precursor dispersed homogeneously in the polymer.

We show that CdS NCs are formed at low annealing temperature avoiding structural damages and without affecting the functional properties of the MEH-PPV polymer. The NCs diameter ranges between 1.5nm and 4nm depending on the annealing temperature. In addition, no coalescence phenomena of CdS NCs were noticed in TEM observations even at very high particle density (40 wt %).

Ion-beam sputtering (IBS) has been studied as a means for scalable, mask-less nanopatterning of surfaces. Patterning at the nanoscale has been achieved for numerous types of materials including: semiconductors, metals and insulators. Although much work has been focused on tailoring nanopatterning by systematic ion-beam parameter manipulation, limited work has addressed elucidating on the underlying mechanisms for self-organization of multi-component surfaces. In particular there has been little attention to correlate the surface chemistry variation during ion irradiation with the evolution of surface morphology and nanoscale self-organization. Moreover the role of surface impurities on patterning is not well known and characterization during the time-scale of modification remains challenging. This work summarizes an in-situ approach to characterize the evolution of surface chemistry during irradiation and its correlation to surface nanopatterning for a variety of multi-components surfaces. The work highlights the importance and role of surface impurities in nanopatterning of a surface during low-energy ion irradiation. In particular, it shows the importance of irradiation-driven mechanisms in GaSb(100) nanopatterning by low-energy ions and how the study of these systems can be impacted by oxide formation.

The electrical and physical quality of gate and passivation dielectrics significantly impacts the device performance of thin film transistors (TFTs). The passivation dielectric also needs to act as a barrier to protect the TFT device. As low temperature TFT processing becomes a requirement for novel applications and plastic substrates, there is a need for materials innovation that enables high quality plasma enhanced chemical vapor deposition (PECVD) gate dielectric deposition. In this context, this paper discusses structure-property relationships and strategies for precursor development in silicon nitride, silicon oxycarbide (SiOC) and silicon oxide films. Experiments with passivation SiOC films demonstrate the benefit of a superior precursor (LkB-500) and standard process optimization to enable lower temperature depositions. For gate SiO2 deposition (that are used with polysilicon TFTs for example), organosilicon precursors containing different types and amounts of Si, C, O and H bonding were experimentally compared to the industry standard TEOS (tetraethoxysilane) at different process conditions and temperatures. Major differences were identified in film quality especially wet etch rate or WER (correlating to film density) and dielectric constant (k) values (correlating to moisture absorption). Gate quality SiO2 films can be deposited by choosing precursors that can minimize residual Si-OH groups and enable higher density stable moisture-free films. For e.g., the optimized precursor AP-LTO® 770 is clearly better than TEOS for low temperature PECVD depositions based on density, WER, k charge density (measured by flatband voltage or Vfb); and leakage and breakdown voltage (Vbd) measurements. The design and development of such novel precursors is a key factor to successfully enable manufacturing of advanced low temperature processed devices.

The half-Heusler compound ZrNiSn has a quite small solubility for Ni from the stoichiometric composition towards the Ni-rich direction since Ni atoms are not supposed to occupy the vacancy-site. Nevertheless, Co and Ir atoms preferably occupy the vacancy-site of ZrNiSn, which is contrary to the prediction that they would substitute for Ni sites. This implies that the phase stability of the compound gradually changes toward that of the Heusler compound Zr(Ni,M)2Sn (M = Co, Ir). It has been confirmed that there exists a two-phase field between half-Heusler Zr(Ni,Cox)Sn and Heusler Zr(Ni,Co)2Sn. The n-type thermoelectric property of ZrNiSn can be converted to p-type by the addition of Co and Ir within the compositional range of the half-Heusler phase. The occupation of vacancy sites by Co and Ir atoms leads to a drastic reduction in the thermal conductivity owing to the enhancement of phonon scattering. With further Co addition, the Heusler phase Zr(Ni,Co)2Sn alloys show metallic behavior.

Resorcinol formaldehyde (R/F) aerogels have been used in a variety of laser targets for Inertial Confinement Fusion (ICF) experiments in the form of thin films, cast shapes such as cylinders and cubes, and hollow and solid microspheres. Besides ICF experiments, R/F aerogel can be used for capacitors, batteries, thermal insulation, absorption/filtration media, and chromatographic packing applications. Traditionally, R/F aerogel is synthesized using a 2-step (base/acid catalysis) polycondensation reaction. We have developed a novel process to synthesize the R/F aerogel using free radical UV initiator at room temperature in 10 minutes using a UV light source. This paper will review this process, which was developed to synthesize R/F aerogels using UV-free radical initiators. Scanning electron microscopy results will also be discussed to show that the aerogel pore structure is similar to traditional R/F aerogels. Fabrication of solid and hollow microspheres for ICF experiments using this R/F aerogel synthesis technique and the technique’s limitations will also be discussed.

Simple NMR techniques can provide an absolute quantification of the quality of the orientational order of discotic columnar phases, provided the anisotropic local magnetic interactions are thoroughly characterized. For the prototypical discotic liquid crystal hexapentoxy-triphenylene, we measure the 13C chemical shift anisotropy of the triphenylene carbons, and use this result to analyze the orientational order, that occurs through a first order phase transition from the high temperature liquid phase, and is almost saturated (order parameter close to 0.85).

We review microstructures and properties of metal matrix composites produced by severe plastic deformation of multiphase alloys. Typical processings are wire drawing, ball milling, roll bonding, equal-channel angular extrusion, and high-pressure torsion of multiphase materials. Similar phenomena occur between solids in frictional contact such as in tribology, friction stir welding, and explosive joining. The resulting compounds are characterized by very high interface and dislocation density, chemical mixing, and atomic-scale structural transitions at heterointerfaces. Upon straining, the phases form into nanoscaled filaments. This leads to enormous strengthening combined with good ductility, as in damascene steels or pearlitic wires, which are among the strongest nanostructured bulk materials available today (tensile strength above 6 GPa). Similar materials are Cu-Nb and Cu-Ag composites, which also have good electrical conductivity that qualifies them for use in high-field magnets. Beyond the engineering opportunities, there are also exciting fundamental questions. They relate to the nature of the complex dislocation, amorphization, and mechanical alloying mechanisms upon straining and their relationship to the enormous strength. Studying these mechanisms is enabled by mature atomic-scale characterization and simulation methods. A better understanding of the extreme strength in these materials also provides insight into modern alloy design based on complex solid solution phenomena.

CrAlSiN/W2N nanolayered coatings were prepared by direct current magnetron sputtering. The modulation periods of multilayer coatings were controlled in the range from 3 to 20 nm. From the low angle x-ray diffraction and high angle x-ray diffraction (XRD) satellite peaks, the superlattice structure of these coatings was evidenced. The modulation periods of multilayer coatings were obtained precisely by the low angle XRD and high angle XRD satellite peaks methods. The detailed layered structure was further investigated by high-resolution transmission electron microscopy. Because of the dense and smooth nanolayered microstructure, the CrAlSiN/W2N multilayer films exhibited excellent microhardness. With an appropriate modulation period of 8 nm, the hardness reached a maximum around 40 GPa. The hardness enhancement is attributed to the large lattice mismatch and strengthening of superlattice structure, which is confirmed by XRD and transmission electron microscopy.