We have developed the atomic force microsocpy (AFM) to measure the complex shear modulus, G*, of a large number of cells. In the AFM technique, live cells were arranged in a micro-fabricated glass substrate under the physiological conditions, and the AFM force measurement was examined in many different cells automatically. The results shown in the previous studies revealed that the frequency-dependent G* was well fitted to the so-called structural damping model, which consists of a single power-law function with a Newtonian viscous effect. However, the detail relationship has not been understood. The aim of this study was to verify the relationship between the storage and loss moduli. As results, we found that the relation between the hysteresivity (the ratio of the storage and loss moduli) and the power-law exponent was in good agreement with the structural damping model, and the result was the same as that observed in magnetic twisting cytometry (MTC), in which cells were cultured on flat substrates. This result indicated that the AFM technique presented here becomes a useful technique for precisely measuring the statistical behavior of single cell rheology.

A transparent colloidal solution of YVO4:Bi3+,Eu3+ nanophosphor is prepared by the wet chemical synthesis in the presence of sodium citrate. When an ethylene glycol solution of Bi(NO3)3, aqueous solutions of (Y,Eu)(NO3)3, sodium citrate, and Na3VO4 are mixed and aged at 85 °C, crystalline YVO4:Bi3+,Eu3+ spherical nanoparticles of ∼ 20 nm in size are formed via the amorphous precursor during aging, as confirmed by X-ray diffractometry and transmission electron microscopy. The crystallization completes at the aging time of ∼ 25 min. At the same time, a sudden reduction in the hydrodynamic size is observed by dynamic light scattering analysis, and the colloidal solution becomes transparent to naked eyes. The nominal molar percentage of sodium citrate relative to the sum of metallic ions, Y3+, Bi3+, and Eu3+, affects the particle size and the aggregation property of the nanoparticles. The sample prepared at 50 mol% citrate, followed by aging at 85 °C for 60 min have the minimum mean size of primary nanoparticles, 21 nm, the minimum mean hydrodynamic size, 36 nm, and hence the highest transparency.

In this paper, we report the spectral response measurement of Schottky solar cells with conventional quantum dots (QDs) and high-density quantum dot molecules (HD-QDMs) as active layers. 3-stack HD-QDMs Schottky structure is compared to 15-stack QD Schottky structure and control sample without QDs. 15-stack conventional InAs QDs give narrow response peak centered at 907 nm while 3-stack InAs HD-QDMs give broad peak between 915 and 985 nm. Both spectral responses are extended beyond the band edge of GaAs, i.e. 870 nm. 42 % more photovoltaic power could be evident from the extended spectral response curve comparing to that of GaAs bulk sample without dots.

The main indicators for the evaluation of the safety of a geological repository are the dose or the risk that are estimated for a sufficiently representative set of possible evolution scenarios. In recent years complementary sets of safety and performance indicators have been developed within national geological disposal programmes and international projects. Whereas safety indicators aim at giving an indication on the level of safety provided by the repository system, performance indicators aim at illustrating how the repository system works. Most sets of performance indicators that have been introduced hitherto in safety cases of geological repositories are related to the multi-barrier concept; they quantify or illustrate the contribution of the main engineered and natural barriers to the confinement of the radionuclides within the repository system. However, the application of the defence-in-depth principle to geological disposal has led to the introduction of safety functions in safety cases. Because of the paramount role played by the multi-safety-functions concept in recent safety cases, we have derived performance indicators that quantify the contribution of the main safety functions to the confinement of radionuclides in the geological repository system. The considered safety functions are containment, limitation of release and retardation. The proposed performance indicators are based on time-integrated activity or radiotoxicity fluxes released from the main successive compartments of the repository system. The proposed indicators can be applied to individual radionuclides as well as to a weighted sum of all radionuclides.

Self-assembly is a promising technique to overcome fundamental limitations with integrating, packaging, and generally handling individual electronic-related components with characteristic lengths significantly smaller than 1 mm. Here we briefly summarize the use of capillary and magnetic forces to realize two example microscale systems. In the first example, we use capillary forces from a low melting point solder alloy to integrate 500 μm square, 100 μm thick silicon chips with thermally and chemically sensitive metal-polymer hinge actuators, for potential medical applications. The second example demonstrates a path towards self-assembling 3-D silicon circuits formed out of 280 μm sized building blocks, utilizing both capillary forces from a low melting point solder alloy and magnetic forces from integrated, permanent magnets. In the latter example, the utilization of magnetic forces combined with capillary forces improved the assembly yield to 7.8% over 0.1% achieved previously with capillary forces alone.

Scanning probe microscopy (SPM) was used to probe piezoelectric vibrations and local conductivity in CaCu3Ti4O12(CCTO) ceramics at room temperature. Piezoelectric contrast was observed on the polished surfaces of CCTO in both vertical (out-of-plane) and lateral (in-plane) modes and depended on the grain orientation varying in sign and amplitude. The piezoelectric contrast is shown to be controlled by the electrical bias (local poling) and displayed a ferroelectric-like reversible hysteresis accompanied with a change of the phase of piezoelectric signal. Flexoelectric effect (strain-gradient-induced polarization) due to surface relaxation was invoked to explain the observed contrast inside the grains.

The mechanical properties of arrays of nominally vertically aligned carbon nanotubes, often referred to as turfs, have been measured using nanoindentation and the electrical properties have been measured using electrical contact resistance (ECR) nanoindentation. The elastic properties do not vary significantly between the top and the bottom of the same carbon nanotube turf. Within a single turf the lateral spatial variation is less than 10% when volumes of μm's are probed with the indenter, indicating that each turf can be treated mechanically as continuum on this scale. The electrical properties vary significantly within a single turf on the same scale. This suggests that the use of average mechanical properties for a given vertically aligned turf should be suitable for design purposes without the need to account for spatial variation in structure, and variations in mechanical properties on the micrometer scale are not dependent on spatially distinct defects. However, local contact behavior appears to dominate the electrical behavior on this same length scale.

A modified sol-gel approach to synthesize well-crystallized pure and doped ZnO nanocrystalline powders and thin films has been developed. The attachment of ZnO films onto quartz substrates was optimized by selecting suitable organic agents to control the viscosity of precursor solutions. Thermo-gravimetric analyses on pure and doped precursor solids suggested the need for annealing temperatures above 400 °C to assure the effective crystallization of the oxide phase. The average crystallite size in powders and thin films varied from 25.9 nm to 33.7 nm when pure ZnO films were annealed for 1 hour in the 450 °C - 600 °C range. The average crystallite size ranged between 30 nm and 33 nm in the presence of cobalt (5 at%) and decreased from 33.7 nm to 21.1 nm when scandium ions was used in the 0.0 at% - 10 at% range under similar annealing conditions. UV-vis measurements showed a sharp exciton peak centered at 370 nm whereas photoluminescence analyses detected the characteristic ZnO emission band in the UV region. No photoluminescence band in the visible region, usually attributed to defect states in ZnO, was observed in our measurements. Magnetization measurements revealed a weak ferromagnetism in Co-doped ZnO whereas a clear diamagnetism was evident in the Sc-doped sample.

The basic properties of palladium impurities in silicon carbide, such as solubility or diffusion mechanisms, are far from being well understood. In a recent paper I presented a systematic study of stability and kinetic properties of Pd in cubic silicon carbide using first principles calculations. In this paper I focus on the effect of the presence of palladium in silicon carbide, even in very low concentrations, on the kinetic properties of carbon vacancies. I apply a odel of Pd diffusion through a vacancy mechanism on the carbon sublattice and extract the correlation factors leading to an enhancement of vacancy migration, due to the coupling of iffusion fluxes between vacancies and palladium impurities.

Ta family has been used as barrier to prevent Cu diffusion into interlayer dielectric in IC applications. Recent experiments demonstrated a more severe flatband voltage shift (ΔVFB) occurred for Ta/porous low k dielectrics/Si capacitors compared to that of Cu/porous low k dielectrics/Si capacitors after a moderate bias temperature stress (BTS). The flatband voltage shift under BTS was interpreted as the penetration of Ta ions into porous low k dielectrics. However, this interpretation has been under debate. In this paper, by using Secondary Ion Mass Spectrometry (SIMS) backside sputter depth profile technique, we report a direct evidence of Ta ions inside porous methyl silsesquioxane (MSQ) in a Ta/MSQ/Si structure after BTS.

Solar cells fabricated from a sputtering target with 5% cadmium sulfide (CdS) intermixed cadmium telluride (CdTe) material was studied using Capacitance-Voltage (CV) profiling. The average efficiency of a set of these novel solar cells under one sun illumination was observed to be 7.56%. In contrast with standard sputtered CdS/CdTe cells, the junction capacitance of the mixed compound device was observed to show minimal change in the entire reverse bias range. The element mapping of the film using Bright Field Scanning Transmission Electron Microscopy (BF-STEM) was used to determine the distribution of S, Te, Cd, O, and Cl in CdTe film. From these observations, it is believed that the morphology and composition of the film resulted in a built-in potential which was sufficient to completely deplete the film.

The mechanism of recrystallization as a result of annealing during 600–7200 seconds at 700 °C of a Si-Al, low C electrical steel strip is investigated in samples deformed in tension. The evolution of grain size during annealing is evaluated by optical microscopy and electron backscatter diffraction in the scanning electron microscope. It is found that grain growth starts after an incubation time of 600 s with no apparent evidence of primary recrystallization. After that, the grain size-time relationship exhibits two different stages. Initially, the grain size increases linearly with time up to about 3600 s. During this time, some selected grains grow until they consume the deformed microstructure. In the second stage, the rate of growth decreases significantly and a final grain size of about 150 m is reached after 7200 seconds of annealing. Grain orientation spread maps obtained from EBSD data of deformed and partially recrystallized samples during the stage of linear growth reveals that the growing grains exhibit lower misorientation and therefore smaller stored energy than the non-recrystallized matrix grains. Analysis of image quality maps reveal that the IQ values for {100}<uvw>orientations are higher than those observed for {111}<uvw>orientations thus suggesting that the {100}<uvw>orientations grow at the expense of {111}<uvw>orientations by a mechanism of strain-induced boundary migration.

Surface scratches in a series of controlled epoxy networks (CEN) were measured using a combination of instrumented indentation protocols and laser scanning confocal microscopy. Identical epoxy chemistry with increasing molecular weight between crosslinks provided different viscoelastic relaxation behaviors with the same modulus at ambient conditions. The glass transition temperatures (Tg)ranged between 70°C and 117°C. The high Tg CEN exhibited the lowest penetration depth and the highest elastic recovery. The results are analyzed with respect to the macroscale bulk properties and underlying molecular architecture of the CEN materials.

The last decade has witnessed tremendous progress in the science and technology of thin film silicon (amorphous and nanocrystalline) photovoltaic. The shipment of solar panels using this technology was about 200 MW in 2009; based on announcement of new or expanded production capacity, the shipment is projected to grow ten-times in the next 3-5 years. The key factor that will determine the wide-scale acceptance of the products will be the cost of solar electricity achieved using this technology. Efficiency of solar modules and throughput of production equipment will play a key role. In this paper, we discuss our roadmap to improve the product efficiency and machine throughput.

We report on the use of Zn as an n-type dopant in CuCl thin films for optoelectronic applications, wherein maximum n-type doping of the order of 1018 cm -3 has been achieved. Zn doped nanocrystalline CuCl thin films are successfully deposited on glass and Si substrates by pulsed dc magnetron sputtering. Structural and morphological properties are investigated using X-ray diffraction (XRD) studies and Scanning Electron Microscopy (SEM), respectively. The conductivity of the CuCl:Zn films is examined using the four point probe technique. An order of magnitude increase in the conductivity of CuCl, by the doping with Zn is reported herein. The doped CuCl films display strong room temperature cathodoluminescence (CL) at λ˜ 385nm, which is similar to that of the undoped films. Hall Effect measurements show an n-type conductivity of the doped films.

Significant conductive polymer-based composites consisting of immiscible semi-crystalline polymers PP and PVDF, at different volume ratios loaded with a certain concentration of CB were prepared by blending and sequent hot-pressing technology. The distributing status of CB in the polymers was evaluated through the micrographs of the composite. The percolation threshold of this kind of composite is much lower than those of the individual polymers. Even more, the composite at 1/1 volume ratio of PP and PVDF displays the best conductivity among different ratios at a certain concentration of CB, and it displays an outstanding PTC effect more than five orders of magnitude, and synchronously an enhanced dielectric permittivity about 24.9 at 100 Hz. These inimitable properties may owe to the formation of PP/PVDF co-continuous phases and a double-percolation effect in the composite. The novel polymer-based composite with ultra-low percolation threshold, enhanced PTC effect, as well as the significant dielectric permittivity is promising a potential application.

The influence of adding InF3 as a reducing agent on the oxidation state of Eu in fluoro-chloro- (FCZ) and fluorobromozirconate (FBZ) glass ceramics was investigated using x-ray ab-sorption near edge (XANES) and photoluminescence (PL) spectroscopy. For both materials, it was found that InF3 decreases the Eu2+-to-Eu3+ ratio significantly. PL spectroscopy proved that an annealing step leads to the formation of Eu-doped BaCl2 and BaBr2 nanocrystals in the FCZ and FBZ glasses, respectively. In the case of FCZ glass ceramics the hexagonal phase of BaCl2 could be detected in indium-free and InF3-doped ceramics, but only for InF3 containing FCZ glass ceramics a phase transition of the nanoparticles from hexagonal to orthorhombic structure is observed. For the FBZ glass ceramics, the hexagonal phase of BaBr2 can be formed with and without indium doping, but only in the indium-free case a phase transition to orthorhombic BaBr2 could be found.

Highly crystalline superparamagnetic Fe3O4 nanoparticles coated by poly-vinylpyrrolidone (PVP) were prepared by simultaneous thermal decomposition of ferrous and ferric inorganic salts in polyethylene glycol (PEG) with molecular weight 200. The magnetic particles have a diameter in the range of 8-15 nm, and after exchange with citric acid diammonium salt, they transform into very stable super hydrophilic colloidal solutions. The presence of magnetite phase was confirmed using powder X-rays diffraction (XRD) and Mössbauer spectroscopy, while thermogravimetric analysis and FT-IR spectroscopy confirmed the presence of PVP or citrate anions on the nanoparticles surface. The magnetic properties revealed superparamagnetic behavior, with the composite material showing a saturation magnetization up to 57 emu/g. The Fe3O4 nanoparticles prepared by this modified polyol process are suitable for biomedical applications because of the biocompatibility of citrate anions. Magnetic hyperthermia experiments in neutral water solutions shows that the particles induce fast heating rates with specific absorption rate (SAR) values which reached 57.53 W/gFe, when the concentration of iron is 11.2 mgFe/ml.

The alpha-decay of plutonium leads to the age-related change in physical properties.This paper presents updated results of age-related effects on enriched and reference alloys measured from immersion density, dilatometry, and mechanical tests. After nearly 100 equivalent years of aging, both the immersion density and dilatometry show that the enriched alloys are decreasing in density by less than 0.002% per year and now exhibit a near linear density decrease, without void swelling. The tensile tests show that the aging process increases the strength of plutonium alloys, followed by possible saturation past 70 equivalent years of age. The ultimate goal of this work is to develop capabilities to predict physical properties changed by aging effects.

Antler is an extraordinary bone tissue that displays significant overall toughness when compared to other bone materials. The origin of this toughness is due to the complex interaction between the nanoscale constituents as well as structural hierarchy in the antler material. Of particular interest is the mechanical performance of the interface between the collagen fibrils and considerably smaller volume of non-collagenous protein (NCP) between these fibrils. This paper directly examines the mechanical properties of isolated volumes of antler using combined in situ atomic force microscopy (AFM)-scanning electron microscopy (SEM) experiments. The antler material at the nanoscale is approximated to a fiber reinforced composite, with composite theory used to evaluate the interfacial shear stresses generated between the individual collagen fibrils and NCP during mechanical loading.