Planar assemblies of interlocked cubic blocs have been tested in indentation. Experiments are performed on blocs made of plaster. Influence of key parameters such as the surface roughness, the compression stress and the number of blocs are investigated. A numerical modeling is then proposed based on discrete element method. Each bloc is represented by its centre coordinates. Constitutive equations obtained by finite element simulations are introduced to model the contact between the blocs. The numerical tool is then applied to the case of indentation loading. It is found that the model reproduces all the experimental tendencies.

A low-range pressure sensor (0-100kPa) based on the P(VDF-TrFE) piezoelectric thin film is proposed, where the long-term drift is eliminated by operating near the piezoelectric resonance. The pressure sensor is designed for blood pressure and tissue swelling pressure monitoring. The poled 50μm±1μm P(VDF-TrFE) copolymer film is used as the sensing element, with all fabrication and assembly materials biocompatible. A modified Butterworth-Van Dyke (BVD) [1] equivalent circuit model is used to characterize the sensor behavior. The pressure sensor exhibits negligible drift in weeks of operation. The device shows a sensitivity of 0.038MHz/kPa resonance frequency shift under stress, which leads to a maximum readout change of 1.1%/kPa in the present setup.

Si quantum dot (Si-QD) based multi-color metal oxide semiconductor lighting emission diodes (MOSLEDs) made on Si-rich SiOx grown by detuning RF plasma power in a plasma enhanced chemical vapor deposition (PECVD) system are demonstrated. With the RF plasma powers increasing from 50 to 70 W at 10 W increment, the turn-on voltage and maximum electroluminescence (EL) power red-, green- and blue-color MOSLEDs increase from 70, 90 and 99 V and 7, 26 and 55 nW, respectively. The power-current slope of 0.51, 3.24 and 53.82 mW/A are obtained for these MOSLEDs with corresponding power conversion ratio (PCR) of 5.13×10-6, 2.52×10-5 and 2.47×10-4. Both the turn-on voltage and power slope linearly increase with enhancing thickness of the Si-QD based MOSLED.

Time-resolved photoluminescence spectra of an ensemble of CuCl quantum dots have been measured by an optical Kerr gate method. The excitation photon energy was tuned to resonant energy for two-photon excitation of biexcitons. We observed that the time profiles of biexciton bands were changed from an exponential fast decay to a pulsed shape. This result indicates a transition from amplified spontaneous emission to superfluorescence. These results will introduce a new field of coherent phenomena originating an ensemble of quantum dots.

We report evidence of enhancement in ferroelectricity in thin films of vanadium (V) doped ZnO grown at higher oxygen pressure. This process reduces oxygen deficiency and the material becomes very insulating, which in turn lowers the leakage current through the ferroelectric capacitor. 2 at. % V doped ZnO films, with thickness of approximately 1 μm were grown epitaxially on c-cut sapphire (Al2O3) (0001) at a growth temperature of 600°C. X-ray analysis showed the layers to be epitaxial where the (0002) diffraction peak had a rocking curve FWHM below 1°. The films with higher oxygen pressure were more insulating than the one grown with lower oxygen pressure. The saturation polarization doubled when the growth pressure increased from 300 mT to 500 mT. Time gated ICCD imaging of the ablated plasma during various O2 pressures and how it translated to the film quality are presented.

Soft ionization mass spectrometry (MS) methods [Electro-Spray Ionisation - Fourier Transform Ion Cyclotronic Resonance MS (ESI-FTICRMS) and Matrix Assisted Laser Desorption Ionization coupled with Time of Flight MS (MALDI-TOFMS)] and associated fragmentation techniques appear to be an alternative way providing data on the size, stability and exact chemical composition of nanoparticles and their precursors, and potentially on interactions between particles. We report the application of both mass spectrometry techniques to analyze II-VI semiconductor nanomaterials (CdX with X = S or Se) and their organometallic precursors.

The post-synthetic assembly of nanowires into desired configurations presents a unique challenge. Through the use of a microscope we observed the behaviors of different nanowires during the drying of their solutions. In addition, we also viewed the resulting dried patterns on substrates by AFM and SEM. We found that nanowires are deposited and aligned along the contact line. The evaporation-induced capillary flow carries the nanowires to the contact line and their alignment there is due to self-assembly directed by solvent evaporation. Based on our observations, we developed a contact-line-deposition process and successfully assembled aligned nanowires in proper patterns on substrates.

The standard, time-of-flight method for measuring drift mobilities in semiconductors uses strongly absorbed illumination to create a sheet of photocarriers near an electrode interface. This method is problematic for solar cells deposited onto opaque substrates, and in particular cannot be used for hole photocarriers in hydrogenated amorphous silicon (a Si:H) solar cells using stainless steel substrates. In this paper we report on the extension of the time-of-flight method that uses weakly absorbed illumination. We measured hole drift-mobilities on seven a Si:H nip solar cells using strongly and weakly absorbed illumination incident through the n-layer. For thinner devices from two laboratories, the drift-mobilities agreed with each other to within our random error of about 15%. For thicker devices from United Solar, the drift-mobilities were about twice as large when measured using strongly absorbed illumination. We propose that this effect is due to a mobility profile in the intrinsic absorber layer in which the mobility decreases for increasing distance from the substrate.

CA-125 and carcinoembryonic antigen (CEA) are two biomarkers present in blood that can indicate the presence of ovarian cancer. They can also be used, both in conjunction with each other and independently, to determine the effectiveness of the treatment being meted for the disease. A label-free multiplexed interdigitated electrode array (IDEA) immunosensor was developed to detect both CA-125 and CEA in buffer solution at levels typically seen in patients with ovarian cancer . Electrochemical impedance spectroscopy was used to measure the increase in impedance when a binding event occurred between the target antigen and its specific antibody that was anchored to the surface of an interdigitated electrode array. CA-125 was detected in concentrations as low as 10units/mL and as high as 80units/mL. CEA was detected in concentrations as low as 1pg/mL and as high as 10μg/mL.

Two important goals in stem cell research are to control the cell proliferation without differentiation, and also to direct the differentiation into a specific cell lineage when desired. Recent studies indicate that the nanostructures substantially influence the stem cell behavior. It is well known that mesenchymal stem cells (MSCs) are multipotent stem cells that can differentiate into stromal lineages such as adipocyte, chondrocyte, fibroblast, myocyte, and osteoblast cell types. By examining the cellular behavior of MSCs cultured in vitro on nanostructures, some understanding of the effects that the nanostructures have on the stem cell’s response has been obtained. Here we demonstrate that TiO2 nanotubes produced by anodization on Ti implant surface can regulate human mesenchymal stem cell (hMSC) differentiation towards an osteoblast lineage in the absence of osteogenic inducing factors. Altering the dimensions of nanotubular-shaped titanium oxide surface structures independently allowed either augmented human mesenchymal stem cell (hMSC) adhesion at smaller diameter levels or a specific differentiation of hMSCs into osteoblasts using only the geometric cues. Small (˜30 nm diameter) nanotubes promoted adhesion without noticeable differentiation, while larger (˜70 - 100 nm diameter) nanotubes elicited a dramatic, ˜10 fold stem cell elongation, which induced cytoskeletal stress and selective differentiation into osteoblast-like cells, offering a promising nanotechnology-based route for novel orthopaedics-related hMSC treatments. The fact that a guided and preferential osteogenic differentiation of stem cells can be achieved using substrate nanotopography alone without using potentially toxic, differentiation-inducing chemical agents is significant, which can be useful for future development of novel and enhanced stem cell control and therapeutic implant development.

By changing the high school science curriculum from Freshman Science, Biology, Chemistry, and Physics (BCP); to Physics, Chemistry, and Biology (PCB), we have an opportunity to create a new Senior level science elective. The entire high school science core curriculum has been reviewed and parts rewritten to create a coherent, integrated program based on common themes such as energy, particulate nature of matter, and forces. Nanoconcepts including size and scale and surface area to volume ratio are integrated where appropriate. In our school, we began PCB during the 2008-2009 academic year. In anticipation of these students becoming upperclassmen, a capstone elective course of Materials Science has been developed based on scientific models and literacies shaped in the PCB course sequence. Deployment of this new model centered course is set for the 2010-2011 school year.

In recent years the increasing oil prices and the need for carbon-free energy to limit global warming have resulted in a revival of interests in nuclear energy. Advanced nuclear fuel cycles are being studied worldwide. They aim at making more efficient use of the available resources, reducing the risk of proliferation of nuclear weapons, and facilitating the management of the resulting radioactive waste. Recently, the Red-Impact project has investigated the impact of a number of representative advanced fuel cycles on radioactive waste management, and more specific on geological disposal. The thermal output of the high-level waste arising from advanced fuel cycles in which all the actinides are recycled is reduced with a factor 3 for a 50 years cooling time and with a factor 5 for a 100 years cooling time in comparison with the spent fuel arising from the once-through fuel cycle. This reduction of the thermal output allows for a significant reduction of the length of the disposal galleries and of the size of the repository. Separation of Cs and Sr drastically reduces further the thermal output of the high-level waste, but it requires a long-term management of those heat generating separated waste streams, which contain the very long-lived 135Cs. Recycling all the actinides strongly reduces the radiotoxicity in the waste, resulting in significantly lower doses to an intruder in the case of a human intrusion into the repository. However, the reduction of radiotoxicity has little impact on the main safety indicator of a geological repository, i.e. the effective dose in the case of the expected evolution scenario; for disposal in clay formations, this dose is essentially due to mobile fission and activation products. The deployment of advanced fuel cycles will necessitate the development of low activation materials for the new nuclear facilities and fuels and of specific waste matrices to condition the high-level and medium-level waste streams that will arise from the advanced reprocessing plants.

We investigated triple ion implanted 4H-SiC BJT with etched extrinsic base regions. To remove the defects induced by ion implantation between emitter and base regions, the characteristics of triple ion implanted 4H-SiC BJT were significantly improved. Maximum common current gain was improved from 1.7 to 7.5.

We prepared fine Cu(In,Ga)Se2 (CIGS) powder suitable for screen printing using a mechanochemical synthesis and wet bead milling. Particulate precursors were deposited in a layer by a screen-printing technique, and the porous precursor layer was sintered into a dense polycrystalline film by atmospheric-pressure firing in an N2 gas atmosphere. The microstructure of CIGS powder and fired CIGS film were observed in an SEM. The wet bead milling was effective for the reduction and homogenization of the average grain size of CIGS powder. The CIGS grains in the film were well sintered and the size of CIGS grains was as large as about 2 μm. The CIGS solar cell showed an efficiency of 3.1%, with V oc of 0.279 V, J sc of 28.8 mA/cm2 and FF of 0.386.

Three kinds of nanocrystalline Co-Cu alloys: a nanocrystalline Co-Cu alloy with nanoscale lamellar structure, a supersaturated solid solution Co-Cu alloy and a nanocrystalline two-phase Co-Cu alloy were processed by electrodeposition, and their mechanical properties were investigated at room temperature. These nanocrystalline Co-Cu alloys showed the high hardness and the low activation volume. The mechanical properties of the nanocrystalline Co-Cu alloys strongly depended on the grain boundary characteristics. Molecular dynamics simulations were performed in the two-phase nanocrystalline Co-Cu alloy to investigate the dislocation emission at the Co/Cu interface. The MD simulations showed that the stacking faults, which are generated by the intense geometrical strain at the Co/Cu interface, play an important role in the dislocation emission.

Carbon nanotubes with their attractive properties, one-dimensional character, and their large aspect ratio are ideal candidates for a variety of applications including energy storage, sensing, nanoelectronics, among others. We have studied the growth of carbon nanotubes on copper substrates using a nickel thin film as a catalyst. The catalyst was sputtered in a chamber having a base pressure in the ultra-high-vacuum regime. By adjusting the sputtering parameters, the effects of the morphology and the thickness of the nickel catalyst on the growth of carbon nanotubes have also been investigated. Multiple hydrocarbon sources as carbon feedstock (methane, acetylene and xylene) and corresponding catalyst precursors and varying temperature conditions were used during the Chemical Vapor Deposition (CVD) process to understand and best determine the ideal conditions for carbon nanotube growth on copper. Correlation between the thickness of the thin film nickel catalyst and the carbon nanotube diameter is also presented in the study. Characterization techniques used to study the morphology of the CNTs grown on copper include SEM, TEM and HRTEM, Raman Spectroscopy

Single crystal high purity CVD diamonds have been metallized and calibrated as photodiodes at the National Synchrotron Light Source (NSLS). Current mode responsivity measurements have been made over a wide range (0.2-28 keV) of photon energies across several beamlines. Linear response has been achieved over ten orders of magnitude of incident flux, along with uniform spatial response. A simple model of responsivity has been used to describe the results, yielding a value of 13.3±0.5 eV for the mean pair creation energy. The responsivity vs. photon energy data show a dip for photon energies near the carbon edge (284 eV), indicating incomplete charge collection for carriers created less than one micron from the metallized layer.

In this study, the cation exchange capacity (CEC) and leached exchangeable cations (LC) of montmorillonite purified from bentonite produced in the Tsukinuno bentonite mine, Yamagata, Japan, were measured, and the exchangeable cations in the interlayer of the montmorillonite were discussed. A montmorillonite, in which the soluble minerals were completely removed, was prepared. Kunipia-F and Kunipia-P, for which both bentonites originally contain approximately 100 wt.% montmorillonite, were used as the initial material. All of the measurements were carried out in a N2 atmosphere-controlled glove-box.

The CEC values of montmorillonites for both bentonites (100-110 meq/100g) were similar to data conventionally reported, and the sum of LC was also approximately in good agreement with the CEC values. The share of Na+ in the interlayer of montmorillonite calculated from the LC was about 3/4 of the sum of the LC (≍ CEC), and Mg2+ and Ca2+ occupied about 7 and 19 %, respectively. Although montmorillonite in bentonite produced in the Tsukinuno bentonite mine is known as a Na type, the sum of Ca2+ and Mg2+ occupied about 26 % of all exchangeable cations in the interlayer. Based on these data, the ion exchange reaction constant between Na+ and H+ in the interlayer of montmorillonite was calculated to be -0.07. This is nearly 2 orders of magnitude lower than data that are usually adopted.

A chemical modification process was developed to functionalize graphene with specific groups. Graphene oxide (GO) was successfully functionalized with thionyl bromide which can be used as precursors for further functionalization. Amino terminated-polyethylene glycol (PEG-NH2) molecules were linked to single-layer graphene sheets through covalent bond. FT-IR, SEM and UV-vis spectroscopy techniques were used to characterize PEG modified graphene oxide and PEG modified reduced graphene oxide (PEG-RG). PEG-RG could disperse in water, tetrahydrofuran and ethylene glycol, with individual, single-layer graphene sheets spontaneously. The dispersion behavior of PEG-RG in an aqueous solvent has been investigated. A series of solutions of PEG-RG with concentrations of 0.001% to 1.5% were prepared and the PEG-RG dispersions exhibited long-term stability. In addition, a PEG-RG film with layered structure and high conductivity has been successfully prepared by filtration.

Despite much progress in recent years, the nature of microcracking in bone at the nano-meter scale is still not well understood. This is partly due to the complexity of bone's hierarchical structure, but also to the difficulty of detecting cracks at very fine scales. Bone microcracking is typically detected using fluorescent dye staining techniques followed by optical or laser microscopy examinations. However, fluorescence-based methods are limited to sub-micron resolution and do not fit three-dimensional imaging such as micro-CT or high resolution imaging such as electron microscopy. This pilot study explores the potential of a heavy metal staining technique to label nano-sized cracks in bone that could be detected by electron microscopy and, albeit at a larger scale, by micro-computed tomography. Upon further development, the method described here may lead to the nano-meter scale characterization of bone microcracking.