In this study, aluminized, boronized, chromized and siliconized gray cast iron plate specimens were prepared, and their microstructures and tribological properties were investigated. The surfaces of the aluminized, boronized, chromized and siliconized specimens mainly consisted of FeAl, Fe2B, (Cr, Fe)23C6 and FeSi phases, respectively. Also, the surface of the boronized specimen exhibited the highest microvickers hardness of all the specimens. The aluminized, boronized and chromized specimens exhibited friction coefficients as low as the non-coated specimens when sliding against AISI 52100 steel ball specimens in poly-alpha-olefin. In addition, the boronized and chromized specimens exhibited much higher wear resistance than the non-coated specimens.

Oil industry is very strategic for any country. Not only for their market share and their budgets, but also for the critical infrastructure interdependences that creates. Considering statistics and fractal geometry as a support for analysis, interpretation of data and as an aid in taking decisions, this paper deals with data obtained in 1994 and 2004 from the inspection of the onshore pipelines in Mexico. Making use of software Benoit and ITSM-2000, the time series were found to have a fractal behavior. Further analysis and contrast with a previous research base on artificial neural networks was also accomplished. As a result it was obtained a forecast for 2014, based on the sum of the time series of data.

A high-density non-equilibrium atmospheric pressure plasma (NEAPP) applied for inactivating fungal spores of P. digitatum is introduced as an environmentally safe and rapid-inactivation method. The contributions of ozone, ultra violet (UV) radiation and ground-state atomic oxygen in the NEAPP on the inactivation of the spores are evaluated using colony count method.

The absolute densities of ozone were measured by using ultraviolet absorption spectroscopy. The ozone density increased from 2 to 8 ppm with an increase in the distance from the plasma source, while the inactivation rate decreased. The inactivation rate of plasma was evaluated to be thousand times higher than that of an ozone generator using the integrated number density of ozone. In addition, it was clarified that the contribution of UV radiation to inactivation was not dominant for P. digitatum inactivation by NEAPP by filtering the active species using quartz plate. From these results, we can speculate that the inactivation efficiency of reactive oxygen species (ROS) will be larger than those of others.

In order to investigate the effect of ground-state atomic oxygen as one of ROS, the inactivation of P. digitatum spores using an oxygen radical source that employs a high-density atmospheric-pressure O2/Ar plasma. The absolute O density was measured to be 1.4×1014 and 1.5×1015 cm–3 using vacuum ultra violet absorption spectroscopy (VUVAS) using a microdischarge hollow cathode lamp. The behaviors of the O densities as a function of O2/(Ar+O2) mixture flow rate ratio correspond to that of the inactivation rate. This result indicates that ground-state atomic oxygen is concluded to be the dominant species that causes inactivation.

Phase-change memory materials (PCMMs) are semiconductors that exhibit rapid order-disorder transition under electrical or optical pulse excitation. Currently thin-film-based PCMMs play a dominant role in fabrication of non-volatile memory devices. In contrast, phase-change nanowires (PCNWs) have the potential to overcome future challenges such as high data density and low power consumption. Among the various methods to synthesize PCNWs, the vapor-liquid-solid method has been reported previously. In this paper, we report synthesis of Sb-Te PCNWs using a templated electrochemical method. Nanoporous anodic aluminum oxide (AAO) was used as a template for the growth of nanowires. Sb-Te PCNWs with different compositions, diameters and aspect ratios were grown inside the AAO template by electrodeposition. Composition and structure of these nanowires were characterized by energy dispersive X-ray spectroscopy, X-ray diffraction, and scanning and transmission electron microscopy. It is found that electrodeposition through nanosized channels results in materials that are quite different from those electrodeposited on unrestricted surface. The mechanism of nanowire formation inside the channels of AAO template is discussed.

The leaf petiole is an organ that connects the leaf blade to the stem of a plant. From a structural viewpoint, the petiole resembles a cantilever beam that withstands torsional loading due to wind action and bending deformation due to gravity acting on the leaf blade. During growth, the petiole develops defined structural features at multiple length scales, which synergistically determine its mechanical response to external stimuli. The focus of this study is on the hierarchical level (n=3) of the cellular tissue. The goal is to capture the elastic properties of the cellular tissues of the leaf petiole in Philodendron melinonii at that hierarchy. Since the microstructure of the plant tissues resembles a non-periodic cellular pattern, we resort to a 2-D Finite Edge Centroidal Voronoi tessellation (FECVT) to generate a realistic network of polygonal cells. An analysis based on finite element analysis (FEA) is performed to explore the relation between the effective stiffness of Voronoi model and the properties of the cellular tissue. The effective (homogenized) elastic properties of the cellular tissue can be used to calculate the overall flexural and torsional stiffness of the P. melinonii petiole. The FEA of the Voronoi microstructure depicts the anisotropic stiffness properties of the P. melinonii tissue and its dependence with the graded cellularity.

The mechanical behavior of nanocomposites is critically dependent on their structural composition. In this paper we use Focused Ion Beam (FIB) microscopy to prepare surfaces from a layered polymer nanocomposite for investigation using phase contrast atomic force microscopy (AFM). Phase contrast AFM provides mechanical information on the surface examined and, by combining with the sequential cross-sectioning of FIB, can extend the phase contract AFM into three dimensions.

Grain boundaries are the dominating type of defect in nanocrystalline materials. Understanding their properties is crucial to the comprehension of nanocrystalline materials behavior. A facile thermodynamic model for alloy grain boundaries is developed. The macroscopic analysis is based on established descriptions of metallic solutions and the universal equation of state at negative pressure, using mainly parameters obtainable from measurements on macroscopic samples. The free energy of atoms in grain boundaries is derived as a function of excess volume, composition, and temperature. Interfacial enrichment is computed using equilibrium conditions between bulk phase and grain boundaries. The excess volume of symmetric ‘100’ tilt grain boundaries in Cu as a common system is obtained by atomistic computer simulation. In a general case the predictions of the proposed model are compared to experimental grain boundary segregation data, yielding a good match. The near-equilibrium solubility of Ag in nanocrystalline Cu and of Cu in nanocrystalline Fe is calculated.

The shear stress relaxation of a thermally reversible, physicallyassociating solution formed from a triblock copolymer in solvent selectivefor the mid-block was found to be well described over a broad temperaturerange by a stretched exponential function with a temperature independent‘stretching exponent’, β ≈ 1/3. This same exponent valuehas been suggested to have particular significance in describing structuralrelaxation in a wide range of disordered viscoelastic materials ranging fromassociating polymer materials (‘gels’) to glass-forming liquids. We quantifythe temperature dependence of the high frequency, or short time, shearmodulus as function of temperature and find that this property also followsa variation often observed in gels and glass-forming materials.

We suggest a model explaining nonlinear dependences of critical current Jc in YBCO epitaxial films. Two features of YBCO are taken into account: twin domain structure in orthorhombic phase and the anisotropy of uniaxial strain dependence of Tc . Applied strain changes elementary pinning force of the defects located at low-angle dislocation boundaries between differently oriented twin domains. Account of Tc dependence on strain this leads to approximately parabolic strain behavior of Jc . We have obtained analytical expressions for the “initial strain”, which actually describes a natural misbalance between numbers of grain boundaries separating a and b oriented domains, as well as for “strain sensitivity”, which is determined by Tc dependence on uniaxial a and b strains and by the effective redistribution of vortices. Other experimentally observed effects, such as temperature, magnetic field and two-peak strain dependences of J c, are shown to be described in the framework of suggested model.

This work describes the design and operation of two microfluidic emulsion and foam generators. The difference between the two devices consists in the geometry of the output channel - in one case, we used a straight microchannel, whereas in the second case we implemented a fractal channel output geometry. While both devices can produce highly monodisperse foams and emulsions at high throughput (coefficient of variation CV≈1.5% and production frequency of up to 2.5kHz per channel with a total of 256 micro channels capable, in theory, of operating in parallel), the actual CV at the exit of the device was significantly higher due to interactions between adjacent droplets or bubbles. Using a combination of high-viscosity continuous phase liquid and low-solubility gas phase resulted in improved monodispersity. In these conditions, the fractal output channel geometry resulted in the lowest overall CV (≈3%) at the exit of the device for both foam and emulsion production, due to an inhibition of aging and coalescence phenomena as compared to the straight channel.

We report the synthesis, characterization, and implementation of various naphtho[2,3- b:6,7-b’]dithiophene (NDT)-based donor molecules for organic photovoltaics (OPVs) When NDT(TDPP)2 (TDPP = thiophene-capped diketopyrrolopyrrole) contains all branched 2- ethylhexyl chains and is combined with the electron acceptor PC61BM, a power conversion efficiency (PCE) of 4.06±0.6% is achieved. This respectable PCE is attributed to the broad, high oscillator strength visible absorption, the ordered molecular packing, and a high hole mobility of 0.04 cm2·V-1·s-1. We find utilizing linear C-12 side chains on either the TDPP or NDT framework dramatically increases the d-spacing, which directly correlates with inferior OPV device performance. This leads to the conclusion that the selection of an appropriate side chain plays a key role in determining OPV device performance of a small molecule donor.

The motivating principle behind this research is the development of small, wearable devices that would use humidity and temperature measurements as metrics for health monitoring. If it is to be useful as a health monitoring tool, the device needs to respond quickly and predictably to changes in humidity. Collagen is shown to be a viable humidity sensing material for use in capacitive relative humidity (RH) sensors. As a natural by-product of meat and leather industries, collagen presents itself as an interesting and inexpensive alternative to polyimide dielectric sensing materials. We used gelatin, a partially hydrolyzed form of collagen, to allow for easier spin coating. We have successfully fabricated devices by depositing a collagen thin film (1.2 μm) via spin coating, followed by Au/Pd electrodes (60 nm) via sputter coating. A plastic mask made from a rapid prototyping machine was used during physical vapor deposition (PVD) to pattern electrodes. This simple method eliminates the need for the use of more complicated photolithography processes. Interdigitated electrodes (rather than parallel plate electrodes) form a 6 mm wide, planar capacitor structure that has little dependence on dielectric thickness and is not affected by dielectric swelling. Initial findings indicate that these devices very closely match the results of the commercial relative humidity sensor used for reference. The capacitance-humidity relationship is shown to be non-linear, with an average change of 3 fF for every 1% change in RH around 60% RH, and an average change of 7 fF for every 1% change in RH around 80% RH. In this work, we present the fabrication and characterization of these novel collagen-based relative humidity sensors.

II-VI compound semiconductor ZnO has a potential for high radiation hardness since large threshold displacement energy of constituent atoms can be expected due to the small unit-cell volume and large bandgap energy of 3.37 eV. In order to study the radiation hardness, singlecrystalline c-axis-oriented O-polar ZnO films with and without two-dimensional electron gas, a Zn-polar ZnO bulk crystal, and a Ga-polar GaN bulk crystal for comparison, were irradiated by an 8 MeV proton beam using a tandem-type accelerator. The radiation damage increased the electrical resistance and decreased the photoluminescence (PL) intensity of these samples with the increase of proton fluence over specific threshold values. In agreement with the expectation, ZnO samples were revealed to have superior radiation hardness; the threshold fluences for the deterioration of PL intensity were 3×1013 p/cm2 for the GaN bulk crystal, 2×1014 p/cm2 for the ZnO bulk crystal, and 5×1014 p/cm2 for the two ZnO films, in accordance with the order of the threshold fluences for the electrical resistance increase. The effect of post-irradiation annealing was also studied for these damaged bulk crystals; both electrical and optical properties of the ZnO bulk crystal were almost recovered to the pre-irradiation values, however, only the electrical properties of the GaN bulk crystal were recovered, by the annealing up to 700°C. Such a rapid recovery of the ZnO bulk crystal indicates the easy annihilation of Zn vacancy complexes acting as non-radiative centers by the recombination with interstitial Zn atoms. Since the migration barrier height energy of interstitial Zn atoms is known to be so small that it might occur even at room temperature, we ascribed the superior radiation hardness of ZnO crystals to the restoration of damage-induced defects by a self-annealing effect during irradiation.

Metallic quantum clusters are stable structures that can exhibit many useful properties. Clusters can be ligand stabilized in aqueous environments to expand their usefulness as biosensors. There are some limitations in characterizing the physical and chemical properties of individual water soluble clusters. This report describes initial results of a new approach for detecting and characterizing individual gold nanoclusters (Au25(SG)18) in an aqueous solution with nanopore-based resistive pulse sensing. Here the nanopore is a single alpha hemolysin from Staphylococcus aureus. Clusters that enter through the cis side of the pore (large vestibule) usually create shallow current blockades with a mean residence time of several milliseconds. Clusters that enter through the trans side of the pore (narrow lumen) create deeper blockades that are either very short (∼200 μs), long lived (∼50 ms) or trapped (>10s). The short and long lived blockades yield sufficient statistics to help characterize the clusters and the trapped state events may allow for additional analysis and controlled delivery of individual clusters. We demonstrate the possibility of this additional analysis by performing I-V measurements on individually trapped clusters. These show an optimal voltage for confining a cluster within the pore.

Currently in the nuclear industry, surface contamination in the form of radioactive metal or metal oxide deposits is most commonly removed by chemical decontamination, electrochemical decontamination or physical attrition. Physical attrition techniques are generally used on structural materials (concrete, plaster), with (electro)chemical methods being used to decontaminate metallic or painted surfaces. The most common types of (electro)chemical decontamination are the use of simple mineral acids such as nitric acid or cerium (IV) oxidation (MEDOC). Use of both of these reagents frequently results in the dissolution of a layer of the substrate surface increasing the amount of secondary waste which leads to greater burden on downstream effluent treatment and waste management plants. In this context, both mineral acids and MEDOC can be indiscriminate in the surfaces attacked during deployment, e.g. attacking in transit through a pipe system to the site of contamination resulting in both diminished effect of the decontaminating reagent upon arrival at its target site and an increased secondary waste management requirement. This provides two main requirements for a more ideal decontamination reagent: Improved area specificity and a dissolution power equal to or greater than the previously mentioned current decontaminants.

Photochemically promoted processes may provide such a decontamination technique. Photochemical reduction of metal ion valence states to aid in heavy metal deposition has already been extensively studied, with reductive manipulation also being achieved with uranium and plutonium simulants (Ce). Importantly photooxidation of a variety of solution phase metals, including neptunium, has also been achieved. Here we briefly review existing decontamination techniques and report on the potential application of photo promoted oxidation technologies to metal dissolution (including process steels) and to the dissolution of adsorbed actinide contaminants.

ThermoChimie is the thermodynamic data base initially created by ANDRA in 1996, especially designed and qualified for systems of interest for the French high level waste repository concept. This database is supported by an experimental program on actinides and fission products and also on major components of the systems of interest, and it has been continuously updated since its creation. The validation of the database is continuously on-going through geochemical calculations related to the performance assessment of different backfill/buffer materials and/or geological formations. ThermoChimie contains data on major elements (including stability of minerals such as clays, zeolites, cementitious phases), a long list of radioelements, such as actinides and lanthanides, chemotoxic metals, as well as organic and inorganic ligands.

The consolidation of a pictorial surface or the removal of undesiredmaterial from the surface of an artifact, are the most important anddelicate operations in the conservation of cultural heritage. In thiscontribution we report on the synthesis and characterization of twoinnovative systems for the cleaning of works of art: i) highly viscouspolymeric dispersions (HVPDs) of poly(vinylalcohol-co-vinyl acetate) random copolymer (PVAc), and ii)chemical gels from acrylamide - N,N’-methylene bisacrylamide, loaded withinnovative aqueous cleaning systems. These systems were prepared,characterized and tested over artistic surfaces, such as wood and canvas.Rheology and FTIR spectroscopy allowed the characterization of thematerials, and provided evidence that the systems allow an efficientcleaning of the substrates, without leaving residues.

We have used single-walled carbon nanotube field-effect transistor (SWNT-FET) and chemically converted graphene field-effect transistor (CCG-FET) devices to probe the interactions between carbohydrates and their recognition lectins. Porphyrin- and pyrene-based glycoconjugates were used as receptor molecules and the target lectins were two bacterial lectins that present different carbohydrate preference, namely PA-IL, PA-IIL from Pseudomonas aeruginosa and a plant lectin Concanavalin A. The specific binding between lectin and carbohydrate can be transduced to the change in FET device conductance. An initial study with SWNT-FET noncovalently functionalized with porphyrin-based glycoconjugates showed both good selectivity and sensitivity. To compare SWNT and CCG performance, pyrene- and porphyrin-based glycoconjugates were functionalized noncovalently on the surface of CCG-FET and SWNT-FET devices, which were then treated with non-specific and specific lectins. The responses were compared and rationalized using computer-aided models of carbon nanostructure/glycoconjugate interactions. Fluorescence microscopy, atomic force microscopy, UV-vis-NIR spectroscopy and Isothermal titration microcalorimetry (ITC) measurements were used to confirm the electrical results.

The thermoelectric figure of merit ZT depends on the thermal conductivity inverse. uperlattices with periodic thin layers were studied to obtain ZT > 1 due to phonon confinement between their layers. Unfortunately, their synthesis with ZT higher than 1 is hazardous due to lattice mismatches forming dislocations and cracks. Nanowires with low dimensionalities were also proposed. However, as the superlattices, they decrease the thermal conductivity in only one propagation direction. In experiments, these one-dimensional insulating materials usually fail to beat the lowest limit of amorphous Si (+/- 1 W/m/K). In this theoretical study, three-dimensional Ge quantum dot arrays in Si are proposed to obtain an extreme thermal-conductivity reduction. Two decrease effects are shown from a molecular supercrystal model. First, low phonon group velocities are computed by lattice dynamics. Second, near-field scattering is exalted assuming weak interface bonding. This prediction can lead to a significant ZT increase. Indeed, a thermalconductivity global minimum λ* = 0.009 W/m/K is predicted for a Si/Ge supercrystal with nanodot spacing of +/- 30 nm and Ge concentration of +/- 12.5 Ge at.%. This ultralow λ* is computed at 300 K assuming that all Ge nanodots are weakly bonded and scatter the phonons at the Si-Ge interfaces in the geometrical limit. Thermal conductivity evolution is analyzed with respect to the weakly-bonded Ge nanodot density.

The purpose of this research is to develop a fabrication technique of microstructures on nonplanar substrates, investigating so called, optical softlithography. In addition, PDMS roller stamps were duplicated from these structures on curved substrates as the mold, roll micro contact printing was performed successfully.

Micro structuring on nonplanar substrates has not been fully established yet, although several fabrication methods, such as laser direct writing and modified photolithography, were proposed. Moreover, those techniques require still expensive and complex processes. To overcome those drawbacks, optical softlithography using flexible photomasks was developed [1]. Firstly, SU-8 micro structures were fabricated on concave substrates by optical softlithography using PDMS flexible photomasks. As a result, SU-8 structures with 2.5 μm line width and high aspect ratio over 7.9 were fabricated on a concave substrate. Also, experimental parameters for optical softlithography were investigated and established for further fabrications and applications. In addition, the tilting structures were confirmed due to the vertical UV exposure method.

Next, Based on these novel 3D patterning technologies, PDMS roller stamps were fabricated and roll micro contact printing was performed. The roll micro contact printing was investigated by using the customized roll micro contact printing apparatus and the flexible pressure sensor system. We expect this technique can provide various sized roller stamps with various micro patterns for μCP process as well as roll micro contact printing process.