Silver clusters (4-150 nm) anchored on nanostructured silica particles (300-400 m2/g) with closely controlled Ag content and size were made in one-step by scalable flame spray pyrolysis of Ag-nitrate and hexamethyldisiloxane containing solutions. Composite Ag/SiO2 nanoparticles were characterized by S/TEM, EDX spectroscopy, X-ray diffraction, N2 adsorption. The activity of such nanoparticles against the Gram negative bacterium Escherichia coli was investigated by monitoring the recombinantly synthesized green fluorescent protein. It is shown that higher Ag content particles exhibit a stronger antibacterial effect.

Heterogeneous catalysis is a field of major interest in the surface science and development of new supported model catalysts with a narrow size distribution. The possibility to create narrow size distributions is to use the faceted surface structures as self assembled templates on which metal nanoclusters can grow. In the present study, new aspects of adsorbate induced faceting and nanoscale phenomena on adsorbate-covered metallic surfaces are studied on atomically-rough morphologically unstable metallic fcc (Rh) and hcp (Re) surfaces. Formation of oxygen induced faceting of atomically-rough Rh (210) surface has been studied and characterized by means of LEED, STM and AES. The LEED studies confirm the formation of three sided faceted (nanoscale pyramidal structure) Rh(210) surface when the oxygen covered Rh surface annealed to temperature higher than 550K. The facet orientations of the nanopyramid are characterized as two {731} face and a reconstructed (110) face. The excess oxygen overlayer can be removed from pyramidal faceted Rh(210) surface via catalytic reaction at low temperature using CO oxidation or H2 reaction while preserving the pyramidal structure. The average size of the nanopyramids is observed to be dependent on annealing temperature and vary from 12nm to 21nm. The atomically resolved STM images confirm the LEED observations and also revealed that (110) face of nanopyramids exhibits various reconstructions (1×n, n = 2-4) depending on oxygen coverage. Further, oxygen induced nanoscale faceted Re (12-31) surface has been formed which consist of nano-trenches (two sided ridges) with facets in (11-21) and (01-10) direction. These two- sided faceted Re (12-31) surface is used as a template to grow gold nanostructures. Under controlled growth conditions, the gold induced nanostructures are formed on oxygen induced nano-trenched Re (12-31) surface. It is observed that gold grows in the form of islands on the faceted rhenium substrate i.e. at lower coverages (≥0.8ML), it forms 2D islands whereby for higher coverages 3D islands are formed on top of the nano-ridges. The surfaces morphology of the gold covered faceted Re surface changes drastically on annealing, for the temperature >870 K, gold atoms wet the rhenium template while annealing to higher temperature (˜970K) led to the development of a three sided nanopyramids. On further annealing to higher temperatures (>1100K) cause the complete destruction of the faceted structure.LEED and STM studies revealed that the gold induced three sided nanopyramids consists of two faces of original two sided ridges with (11-20), (01-10) orientation and an additional facet in (12-32) direction. The high resolution STM images revealed that the (12-32) facet of the nanopyramid is fully decorated with single atomic zigzag gold nanochain. These faceted surfaces can be potential template for heterogeneous catalysis and development of new supported model catalysts with a narrow size distribution.

Structural and magnetic properties were investigated in the mixed powders of Sn1-x Crx O2 (x = 0.01, 0.02, 0.03, 0.04 and 0.05) in nominal composition. The lattice parameter observed in (110) x-ray diffraction indicates two step changes with increasing Cr content. The occupation of Cr ion at the interstitial position leads to elongation of the lattice parameter for x = 0.01 to x =0.03. Then, the Cr3+ ions are remarkably substituted into the Sn4+ ion site for x = 0.04 to x = 0.05, which results in shortening of the lattice. The lattice parameters for x = 0.01 and 0.02 are larger than x = 0.03 to 0.05. The room temperature ferromagnetism appeared in the sample with x = 0.01 and reaches maximum at the doping rate of x = 0.02; while the magnetization decreases for x > 0.02 was observed. Present study clearly shows the existence of correlation between appearance of ferromagnetism and the structural change.

The microstructural changes during heating of bi-layers of Cu-poor CuInS2 and CuS under different sulfur excess conditions were studied. This was done by means of energy dispersive X-ray diffraction of polychromatic synchrotron radiation in a vacuum setup where the sulfur pressure conditions can be controlled. Understood as the formation of a new microstructure, the recrystallization of the Cu-poor CuInS2 phase was characterized by a change in the reflection profile (from Cauchy-type to Gauss-type), the reduction of the breadth and a subsequent normalized-intensity increase of the 112 reflection. The Cauchy component of the breadth was used to monitor the recrystallization under different sulfur and heating rate conditions. The main results are: a) Cu availability for the consumption of the CuIn5S8 phase is a pre-requisite for recrystallization, b) in presence of the Cu2-xS phase, increased sulfur pressure enhances recrystallization.

Various possible routes for the migration of a CH2 group between the H-terminated 2×1 reconstructed {100} surface and the H-terminated {111} surface of diamond have been explored using a hybrid quantum mechanical/molecular mechanical method. The calculated energies suggest that movement of such surface bound species across step edges should be a facile process under typical diamond growth conditions, and that such migrations are significant contributors to the observed morphologies of diamond grown by chemical vapor deposition methods.

Thermal conductivity of rubrene single crystals is measured for both bulk and film-like crystals down to 0.5 K in order to estimate quantitatively density of crystalline defects through their phonon mean free paths. The temperature profile of the bulk rubrene crystals exhibit pronounced peak at ∼ 10 K in the thermal conductivity as the result of very long mean-free paths of their phonons which indicates extremely low-level defect density in the region of 1015-1016 cm−3 depending on different growth methods. The crystals grown from gas phase tend to have less defects than those grown from solution. It turned out that the film-like crystals have a few times more defect density as the result of the measurement by using newly developed devices for minute crystals.

Dentin matrix protein 1 (DMP1) is an acidic noncollagenous protein which plays an important role in mineralized tissue formation. Dmp1 null adult mice are ricketic and osteomalacic and are a model for hypophosphatemic rickets [1]. Mutation in humans results is Autosomal Recessive Hypophosphatic Rickets [1]. The degree of bone mineralization significantly contributes to bone tissue mechanical properties, but precise relationships and interactions between chemical and mechanical variables are unknown. The objective of this study was to relate the differences in chemical properties in the Dmp1 wildtype (WT) and null (KO) mouse femoral cortical bone to their mechanical properties by using FTIR imaging and Scanning Acoustic Microscopy (SAM). Interactive mechanical (elastic modulus) and chemical images (i.e., mineral/matrix ratios) were generated from the same region of bone at a lateral resolution of ˜10 um. Mechanical analysis showed that elastic modulus, 75 percentile around 7.1 GPa, was ˜60% less in Dmp1 KO than that in WT, in which elastic modulus was 75 percentile around 15.2 GPa. The mineral-to-matrix ratios in Dmp1KO (4.96±1.63) were ˜2 times lower than that in Dmp1 WT (8.65±1.14). The mineral crystallinity and collagen crosslink ratios were not significantly different between KO and WT. Conclusions: The results relate the bone elastic modulus changes in Dmp1WT and KO mice with chemical changes within a specific bone site. These measurements provide a new tool for describing the variability of bone chemical and mechanical properties.

We report on the improved performance of large-area organic solar cells and modules by integrating metal grids directly with the indium tin oxide (ITO), thereby reducing the series resistance contribution from the ITO. Devices with different areas (0.1, 7, and 36.4 cm2) were prepared to study the area-dependency of the organic solar cells based on pentacene and C60 heterojunctions. Modules were prepared in which four individual cells (7 cm2) were connected in series and parallel. For the series connected modules, VOC scales linearly with the number of cells while parallel connected modules exhibited multiplied current density as expected.

Biology has evolved several strategies for attachment of sedentary animals. In the bivalves, byssi abound and the best known example being the protein-based byssus of the blue mussel and other Mytilidae. In contrast the bivalve Anomia sp. has a single calcified thread. The byssus is hierarchical in design and contains several different types of structures as revealed by scanning electron microscopy images. The mechanical properties of the byssus are probed by nanoindentation. It is found that the mineralized part of the byssus is very stiff with a reduced modulus of about 67 GPa and a hardness of ˜3.7 GPa. This corresponds to a modulus roughly 20% smaller than that of pure calcite and a hardness that is about 20% larger than pure calcite. The results reveal the importance of microstructure on mechanical performance.

We design and fabricate metallic photonic crystals with sharp absorption peaks in the infrared regime. We have fabricated a metallic photonic crystal consisting of a triangular lattice of holes in a silicon layer conformally coated with gold at a lattice pitch of 3.8 microns. Conventional lithographic and deep reactive ion etching was used. The photonic crystal exhibits a deep reflection minimum and sharp thermal emission peak near the lattice spacing. Measurements agree well with rigorous scattering matrix simulations. This simple single-layer structure with a single patterned exposure has no emission sidebands and can be scaled to other lattice spacings.

The standardization of thermoelectric generator (TEG) performance measurement is of a major interest for a usage of them in industrial energy harvesting application. The effects influencing the TEG measurement are regarded and are addressed in this article. The dramatic influences of different measurement parameters are pointed out. The output power dependence on the contact pressure is investigated as a major attempt. The influence of contact pressure on the temperature of the TEG-substrate at the hot side is observed with a high resolution IR camera.

Different approaches are discussed in order to obtain the accurate efficiency of a TEG. The heat flux method is influenced by many effects that can falsify the results. The Harman method is used as another approach to determine the figure of merit to calculate the efficiency.

The Mg doped AlN/AlxGa1-xN (0.03 ≤ x ≤ 0.05) short period superlattices (SPSLs) were grown by gas source molecular beam epitaxy on (0001) sapphire substrates. The average AlN mole fraction is ∼ 0.7 and the hole concentration is ∼ 7×1017 cm-3. Contacts formed to the SPSLs using Ni/Au bilayer are found to have specific contact resistance ∼ 5×10-5 Ωcm2 near room temperature and to show weak temperature dependence attributed to activation of Mg acceptors in the AlN barriers of SPSLs. These p-SPSLs are attractive for fabrication of transparent low resistive ohmic contacts for deep UV LEDs.

In order to perturb global warming and realize a sustainable global energy system, enhancements in the energy efficiency are required. One of the reliable technologies to reduce the greenhouse gas emissions and the consumption of fossil fuel that is attracting attention is thermoelectric technology, which can directly convert heat into electricity and consequently increase the energy conversion efficiency of power generation by combustion. Magnesium silicide (Mg2Si) has been identified as a promising advanced thermoelectric material operating in the temperature range from 500 to 800 K. Compared with other thermoelectric materials that operate in the same conversion temperature range, such as PbTe, TAGS (Ge-Te-Ag-Sb) and CoSb3, Mg2Si shows promising aspects, such as the abundance of its constituent elements in the earth’s crust and the non-toxicity of its processing by-products, resulting in freedom from care regarding prospective extended restriction on hazardous substances.

Here we have tried to introduce reusing of industrial waste of Si sludge as a source material for Mg2Si, because the current product inversion rate of Si for semiconductor LSI devices remains at 25 to 30 %, while most of the remainder is disposed of as a waste; this is mainly discharged as sludge from grinding and polishing processes. It is possible that the reuse of this waste Si could be effective in both reducing the cost of source Si and in the reduction of industrial waste. On the other hand, recycled materials of standard lightweight magnesium alloys based on the Mg-Al-Zn-Mn system, such as AZ91 or AM50, were also introduced as a Mg source for Mg2Si synthesis. The concept of this work is a production of wasted heat recovery device using environmentally-benign Mg2Si by means of industrial waste or less pure recycled sources.

The efficiency of a thermoelectric device is characterized by the dimensionless figure of merit, ZT=S2σT/κ, of its constituent thermoelectric material, where S is the Seebeck coefficient, σ is the electrical conductivity, κ is the thermal conductivity, and T is the absolute temperature. As a target for practical use, ZT value exceed unity, which gives about 10 % conversion efficiencies, is expected. So far, we succeeded to obtain the Mg2Si with ZT=1.08 using rather pure Si (99.999% : solar grade) and Mg (99.95%) sources. In this article, we report multifarious fabrication processes in order to realize ZT value as high as unity and the detailed thermoelectric properties concerning Mg2Si initiated from reused Si sludge and the recycled Mg-alloy sources. In conjunction, we will also discuss the practical output-power characteristics of the samples with the formation of Ni electrodes by monobloc sintering. A tentative generated power density from the wasted heat at 773 K was ˜2 KW/m2.

Surface biofunctionalization of group-III nitride semiconductors has recently attracted much interest due to their biocompatibility, nontoxicity, and long-term chemical stability under demanding physiochemical conditions for chemical and biological sensing. Among III-nitrides, aluminum nitride (AlN) and aluminum gallium nitride (AlGaN) are particularly important because they are often used as the sensing surfaces for sensors based on field-effect transistor or surface acoustic wave sensor structures. Patterned self-assembled monolayer (SAM) templates are composed of two types of organosilane molecules terminated with different functional groups (amino and methyl), which were fabricated on AlN/sapphire substrates by combining photolithography, lift-off process, and self-assembly technique. Clear imaging contrast of SAM micropatterns can be observed by field emission scanning electron microscopy (FE-SEM) operating at a low accelerating voltage in the range of 0.5–1.5 kV. In this work, the formation of green fluorescent protein (GFP) antibody microarrays was demonstrated by the specific protein binding of enhanced GFP (EGFP) labeling. The observed strong fluorescent signal from antibody functionalized regions on the SAM-patterned AlN surface indicates the retained biological activity of specific molecular recognition resulting from the antibody–EGFP interaction. The results reported here show that micropatterning of organosilane SAMs by the combination of photolithographic process and lift-off technique is a practical approach for the fabrication of reaction regions on AlN-based bioanalytical microdevices.

Rosette nanotubes (RNTs) are novel, biomimetic, synthetic, self-assembled drug delivery agents. Because of base stacking and hydrophobic interactions, the RNT hollow-tube structure can be used for incorporating drugs. Another advantage of using RNTs is their ability to be injected and become solid at body temperatures for orthopedic applications without the use of any external stimuli (such as UV light or crosslinking agents). The nano-features of RNTs create a favorable, biologically-inspired, cellular environment. In this study, methods to incorporate dexamethasone (DEX, a bone growth promoting drug) into RNTs were investigated. The drug-loaded RNTs were characterized using Nuclear Magnetic Resonance (NMR), Diffusion Ordered Spectroscopy (DOSY) and Ultraviolet-visible Spectroscopy (UV-vis). Results showed that small molecular drugs with hydrophobic aromatic rings were incorporated into RNTs. Subsequent drug release experiments demonstrated that DEX was released from the RNTs and had a positive impact on osteoblast functions. Importantly, compared to other drug carriers, RNTs increased the total drug loading and was the highest when DEX was incorporated during the RNT self-assembly process. Thus, this study offered a novel drug delivery device that itself is bioactive and can be used to deliver a variety of drugs for various orthopedic applications.

Electrospun polymer nanofiber materials have attracted tremendous interest in sensor applications as their effective sensing surface area dramatically increases with decreasing fiber diameter. The highly tunable polymer composite chemistry and surface functionality of the nanofiber material provides a wide platform for exploring different applications, such as filtration media, sound isolation materials, and sensor components. This paper presents a nanofiber sensor platform device composed of electrospun polymer/carbon composite nanofibers combined with electrodes directly printed onto the surface of the electrospun fiber mat. This structure forms an integrated sensor system for detecting various chemical vapors including volatile organic compounds (VOCs) and oxidative gases. In this sensor, the composite polymer nanofibers form a chemo-resistor sensing material, and the conductivity of these composite sensing materials varies with chemical vapor exposure. The sensor performance exhibits very stable baselines with dramatically reduced noise levels compared to conventional interdigitated electrodes. Furthermore, the sensor response to different vapors shows a linear relationship between conductivity change and vapor concentration in the range of ppb – ppm for some analytes, including methanol, chloroform and ozone. The sensitivity and selectivity of these sensors to different vapor analytes will also be discussed.

This study focuses on fracture properties of silicon wafers used by the photovoltaic (PV) industry as substrates for solar cells. In the first part, we numerically model three fixtures that are often used to test the strength of PV wafers. In the second part, we employ our previously developed model to predict strength of the wafers as a function of loading fixture and surface treatment. Surface treatment is simulated by removing damage from the wafer surface.

In the present work we describe an experimental apparatus of very low cost , aiming at the experimental study of the mechanical properties of solid materials, using the method of indentation. The measurements allow, through a simple analysis, the quantitative determination of the materials' hardness and bulk modulus. A very important class of commonly used materials, namely thermoinsulating materials, is proposed for a case study. The method can furthermore be used to demonstrate the elastic and the plastic behavior of materials. The educational exploitation of the specific apparatus at a technical high school class in Larissa (Greece) and at a university physics students' laboratory practice on the subject of mechanical properties of materials are also described. The responses of the students on the whole process, and specifically on observations related to the pedagogical-educational aspects (active participation, challenge of interest, easiness of measurements, easiness of processing experimental data), as well as related to metrological aspects (uncertainty of measurements), were very positive and are also presented and discussed.

The Centre of Experimental Geotechnics, CTU in Prague has recently launched a sprayed backfill technology development programme. Such technology will, most probably, be used during the future construction of deep underground radioactive waste repositories.

The safe disposal of radioactive waste in deep underground geological repositories assumes the construction of a multi-barrier system the aim of which will be to eliminate the potential penetration of hazardous radionuclides into the biosphere over a time span of several hundred thousand years.

With regard to the location in the repository in which the containers will be placed, bentonite will seal the space between the container and the rock mass in the form of a highly compacted bentonite block, while access galleries to the nests will be backfilled with a mixture of natural bentonite and rock. This mixture will be compacted in layers using compacting machinery thus ensuring maximum backfill density during compaction. Following compaction, however, spaces will remain in the gallery vault to which such compacting machines will be unable to gain access. Sprayed clay (sprayed backfill) technology, however, will allow the filling of such voids by injecting backfill so that the material compaction level obtained using this method is at least the same as the backfill compaction level resulting from that using standard compacting machinery (vibration roller, vibration plate compactor etc.).

Sprayed backfill technology is based on shotcrete technology which is a method commonly applied today in the construction of underground structures. Sprayed backfill technology development may involve the use of concrete spraying machines; however the parameter requirements for the spraying of bentonite backfill differ in principal from those which apply to shotcrete.

The article will provide information on the development of sprayed backfill technology, the machinery employed and the sprayed material as well as research results obtained to date.

The theoretical background and technical capabilities of the free liquid surface (nozzle-less) electrospinnig process is described. The process is the basis of both laboratory and industrial production machines known as NanospiderTM and developed by Elmarco s.r.o. Technical capabilities of the machines (productivity, nanofiber layer metrics, and quality) are described in detail.Comparison with competing/complementary technologies is given, e.g. nozzle electrospinning, nano-meltblown, and islets-in-the sea. Application fields for nanofiber materials produced by various methods are discussed. Consistency of the technology performance and production capabilities are demonstrated using an example of polyamide nanofiber air filter media.