Optical biosensor for monitoring proteolytic activity is constructed by DNA-directed immobilization of enzymes onto porous Silicon nanostructures. This sensor configuration allows both protease recycling and easy surface regeneration for subsequent biosensing analysis by means of mild dehybridization conditions. We demonstrate real-time analysis of minute quantities of proteases paving the way for substrate profiling and the identification of cleavage sites. The biosensor is compatible with common proteomic methods and allows for a successful downstream mass spectrometry analysis of the reaction products.

In the work presented here, Ce0.97Cu0.03O2 nanoparticles were synthesized by a microwave-assisted hydrothermal method under different synthesis temperatures. The obtained nanoparticles were tested as catalysts in preferential oxidation of CO to obtain CO-free H2 (PROX reaction). The samples were characterized by X-ray diffraction, transmission electron microscopy (TEM), electron paramagnetic resonance spectroscopy (EPR) and temperature-programmed reduction (TPR). X-ray diffraction measurements detected the presence of pure cubic CeO2 for all synthesized samples. TEM images of the Ce0.97Cu0.03O2 nanoparticles revealed that samples synthesized at 80°C are composed mainly of nanospheres with an average size of 20 nm. The formation of some nanorods with an average diameter of 8 nm and 40 nm in length, and the size reduction of the nanoparticles from 20 to approximately 15 nm is observed with increasing synthesis temperature. EPR spectra indicated that copper is found well dispersed in sample synthesized at 160°C, located predominant in surface sites of ceria. For samples synthesized at 80 and 120°C, the species are less dispersed than in the other one, resulting in the formation of Cu2+−Cu2+ dimmers at the surface of ceria. TPR profiles presented two reduction peaks, one below 400°C attributed to the reduction of different copper species and a second peak around 800°C attributed to the reduction of Ce4+→ Ce3+ species located in the volume of the nanoparticles. The peak related to the reduction of copper species shifts to lower temperatures with increasing synthesis temperature, i.e., the sample synthesized at 160°C is more easily reduced than the ones synthesized at 120 and 80°C. The nanoparticles showed active as catalysts for the CO-PROX reaction. The microwave-assisted method revealed efficient for the synthesis of Ce0.97Cu0.03O2 nanoparticles with copper species selective for the CO-PROX reaction, which reaches CO conversions up to 92% for the sample synthesized at 160°C.

We consider the modeling and simulation of multiscale phenomena which arise in finding the optimal shape design of microcellular composite materials with heterogeneous microstructures. The paper focuses on the solution of the resulting partial differential equation (PDE) constrained structural optimization problem and development of efficient multiscale numerical algorithms which are challenging tools in reducing the computational complexity. The modeling strategy is applied in materials science for microstructural ceramic materials of multiple constituents. Our multiscale method is based on the efficient combination of both macroscopic and microscopic models. The homogenization technique based on the concept of strong separation of scales and the asymptotic expansion of the unknown displacements is applied to extract the macroscopic information from the microscale model.

In the framework of all-at-once approach we find a proper combination of the iterative procedure for the nonlinear problem arising from the first order necessary optimality conditions, also known as Karush-Kuhn-Tucker (KKT) conditions, and efficient large-scale solvers for the stress-strain constitutive equation. We use the path-following predictor-corrector schemes by means of Newton's method and fast multigrid (MG) solution techniques. The performance of two preconditioners, incomplete Cholesky (IC) and algebraic multigrid (AMG), for the resulting homogenized state equation is studied. The comparative analysis for both preconditioners in terms of number of iterations and computing times is presented and discussed. Our interests focus on the parallel implementation of the preconditioning techniques and the use of BoomerAMG as a part of the free software library Hypre developed at the Center for Applied Scientific Computing (CASC), Lawrence Livermore National Laboratory (LLNL).

Capabilities of Atomic Force Microscopy in different modes including Electric Force Microscopy and Kelvin Force Microscopy are reviewed and illustrated on several samples including organic photovoltaics (P3HT/PCBM, PEDOT:PSS). Compositional mapping of these blends is enhanced with a combined use of the modes, and variations of local electric properties are detected down to the nanometer scale. The revealed morphology will assist in development of comprehensive models accounting for the structure-property relationship in solar cells and related devices.

Phase-segregated multiblock copolymers (MBC) as well as covalently crosslinked multiphase polymer networks, which are composed of crystallizable oligo(ε-caprolactone) (OCL) and oligo(ω-pentadecalactone) (OPDL) segments have been recently introduced as degradable polymer systems exhibiting various memory effects. Both types of copolyesterurethane networks can be synthesized via co-condensation of the respective hydroxytelechelic oligomers and 2,2(4),4-trimethyl-hexamethylene diisocyanate (TMDI) as aliphatic linker.

In this work the dual-shape properties as well as the temperature-memory capability of thermoplastics and covalently crosslinked copolyesterurethanes containing OCL and OPDL domains are explored. Both copolyesterurethane networks exhibited excellent dual-shape properties with high shape fixity ratios R f ≥ 93% and shape recovery ratios in the range of 92% to 100% determined in the 2nd and 3rd test cycle, whereby the dual-shape performance was substantially improved when covalent crosslinks are present in the copolymer.

A pronounced temperature-memory effect was achieved for thermoplastic as well as crosslinked copolyesterurethanes. Hereby, the switching temperature T sw could be adjusted via the variation of the applied deformation temperature T deform in the range from 32 °C to 53 °C for MBC and in the range from 29 °C to 78 °C for multiphase polymer networks.

Alkyl-terminated Si nanocrystals (NCs) are synthesized at room temperature by hydride reduction of SiCl4 within inverse micelles. Highly monodisperse Si NCs (2 – 6 nm) are produced by variation of the cationic quaternary ammonium salts used to form the inverse micelles. Transmission electron microscopy imaging confirms the NCs are highly crystalline, while FTIR spectra confirm that the NCs are passivated by covalent attachment of alkanes, with minimal surface oxidation. The photoluminescence intensity of the Si NCs exhibits an inverse relationship with the mean NC diameter, with a quantum yield of 12 % recorded for 2 nm NCs.

The surface morphologies of AlGaN/AlN/GaN HEMT structures were examined by using the atomic force microscopy (AFM).These HEMT structures have been grown by metalorganic chemical vapor deposition (MOCVD) onto the sapphire (0001) substrates where the thicknesses of AlN interlayers were varied from 0 to 5 nm. After the growth of GaN buffer layer, the AlN intermediate and AlGaN top layers were subsequently deposited at 1130°C in an trimethylaluminum (TMAl) and ammonia (NH3) atmosphere. The surface of AlGaN layers shows the thick- and fine-thread patterns.

It was found that the root-mean-square (RMS) roughness of the samples with 0, 0.5, 2.5 and 5nm AlN interlayer thickness are 0.503, 0.534, 0.534 and 0.601nm, respectively. Although the cracks and rougher surfaces show that the qualities of AlGaN barrier layers have slightly degraded in the samples with thicker AlN layer. These phenomena could be attributed to the lattice mismatch and the growth temperature. In addition, the room-temperature two-dimensional electron gas (2DEG) mobility and density analysis were performed on the AlGaN surfaces and the measured results were discussed in detail.

This paper describes a novel ultracapacitor made from carbon nano-onions. Characterization of the material was performed including measurement of the impedance spectra and cyclic voltammetry. A new ultracapacitor model composed of an LRC circuit and a constant phase element was developed along with a parameter extraction procedure. The model was validated using experimental data and simulation.

There are many biological macro-molecules such as nucleic acids, lipids, carbohydrates and proteins. While each of them plays a vital (and interesting) part in life but there is something special about the proteins. Proteins are the key link between the processes of information and replication that take place on a genetic level and the infrastructure of living features. Understanding the properties of proteins is the key to understanding the spark of the life. In this paper we describe our study of various electrical properties of protein when performing measurements at the nanoscale. To achieve this goal we designed and fabricated a nanoelectronic probe. This nano structure consists of four thin film layers. There are two conductive layers and an insulative layer in between. There is also a protective oxide layer as the top most layer. This layer is to prevent the exposure of conductive electrodes to the solution. Underneath the bottom electrode, there is another oxide layer, which can be a thermally grown oxide. This layer insulates the first electrode from the substrate. In this study, while we use non-specific detection of streptavidin protein as a proof of concept, we emphasize that the findings of this study can be extended to specific detection of target proteins, where in this case a specific probe molecule would also be immobilized on the sensor surface.

The thermoelectrical properties of α and γ phases of NaxCo2O4 having different amounts of Na were evaluated. The γ NaxCo2O4 samples were synthesized by thermal decomposition in a metal-citric acid compound, and the α NaxCo2O4 samples were synthesized by self-flux processing. Dense bulk ceramics were fabricated using spark plasma sintering (SPS), and the sintered samples were of high density and highly oriented. The thermoelectrical properties showed that γ NaxCo2O4 had higher electrical conductivity and lower thermal conductivity compared with α NaxCo2O4 and that α NaxCo2O4 had a larger Seebeck coefficient. These results show that γ NaxCo2O4 has a larger power factor and dimensionless figure of merit, ZT, than α NaxCo2O4.

The efficiency of a tantalum nitride interlayer as a diffusion barrier for CeFe4Sb12 thermoelectric material against electrode copper material has been investigated. The thermal stability of CeFe4Sb12/TaN/Cu stackings has been investigated after annealing at 600°C from a microstructural study. CeFe4Sb12 and Cu appear to chemically react through the formation of CeCu2 and Cu2Sb phases whereas no reaction is observed for CeFe4Sb12 with TaN. This study showed that the TaN interlayer cannot inhibit the diffusion of Sb from the skutterudite substrate to the copper electrode but prevents the diffusion of Ce and consequently the formation of the CeCu2 phase.

The stability of the negative electrode electrolyte affects the efficiency and capacity of energy storage in the vanadium redox flow battery (VRFB) system. To explore the stability of vanadium electrolytes, the study prepared five types of V(II) electrolytes that were exposed to air in a fixed open area and monitored the charge state of vanadium ions over time by UV/Visible spectrophotometer. This study succeeded in preparing pure V(II) electrolytes. Five characteristics are found in the UV/Visible spectra, respectively, during the oxidation process from V(II) electrolytes to V(III) electrolytes and V(III) electrolytes to V(IV) electrolytes. The experimental results show that the oxidation rate of a solution of 1 M V(II) electrolytes to V(III) electrolytes and 1 M V(III) electrolytes to V(IV) electrolytes under an atmosphere of air is 4.79 and 0.0089 mol/h per square meter. The oxidation rates of 0.05-1 M V(II) electrolytes to V(III) electrolytes are approximately 96-538 times than that of V(III) electrolytes to V(IV) electrolytes.

By using a thermodynamic model of nanocrystalline alloys the grain size effect on the solubility of carbon in α-iron is calculated. More specifically the enrichment at grain boundaries is predicted to result in a solubility enhancement. An experimental setup is devised to measure carbon solubility in nanocrystalline iron powder in equilibrium with graphite. At 390 °C a solubility of 0.514 at% is determined for nanocrystalline iron with a grain size of 23 nm.

This report will demonstrate broadband, wide-angle, and polarization-insensitive absorption enhancement in ultra-thin films resting on metal substrates that have been etched with arrays of shallow sub-wavelength cylindrical holes. Absorption enhancement will be studied as a function of array geometry, with particular emphasis given to quasiperiodic arrays (a class of deterministic aperiodic arrays that were originally developed to tessellate 2-D planes with regular polygons). Through simulations and experimental data, it was found that absorption enhancement is heavily dependent on the rotational symmetry of the pattern of holes, as well as the inter-hole distance.

A compact spectrometer-on-a-chip featuring a plasmonic molecular interaction region has been conceived, designed, modeled, and partially fabricated. The silicon-on-insulator (SOI) system is the chosen platform for the integration. The low loss of both silicon and SiO2 between 3 and 4 μm wavelengths enables silicon waveguides on SiO2 as the basis for molecular sensors at these wavelengths. Important characteristic molecular vibrations occur in this range, namely the bond stretching modes C-H (Alkynes), O-H (monomeric alcohols, phenols) and N-H (Amines), as well as CO double bonds, NH2, and CN. The device consists of a broad-band infrared LED, photonic waveguides, photon-to-plasmon transformers, a molecular interaction region, dispersive structures, and detectors. Photonic waveguide modes are adiabatically converted into SPPs on a neighboring metal surface by a tapered waveguide. The plasmonic interaction region enhances optical intensity, which allows a reduction of the overall device size without a reduction of the interaction length, in comparison to ordinary optical methods. After the SPPs propagate through the interaction region, they are converted back into photonic waveguide modes by a second taper. The dispersing region consists of a series of micro-ring resonators with photodetectors coupled to each resonator. Design parameters were optimized via electro-dynamic simulations. Fabrication was performed using a combination of photo- and electron-beam-lithography together with standard silicon processing techniques.

Based on the electron configurations of Mo and Zn, the valence electron difference between Mo6+ and Zn2+ is 4. Therefore, a small amount of Mo doping can produce sufficient free carriers to reduce the ion scattering effects. The Mo doped ZnO (MZO) thin film prepared by RF sputtering was studied in this research. Structural, electrical, and optical characteristics of the films were discussed. The MZO film shows a resistivity of 1.1 × 10-2 Ω⋅cm, a carrier concentration of 2.2 × 1021 cm-3,a mobility of 0.63 cm2/V⋅s, and average transparency of 81.0% at both the powers of 20 W to the Mo target and of 125 W to the ZnO target. The MZO film becomes a stable p-type semiconductor at high power process toward Mo target. The film preserves its p-type characteristics after exposure to air for one and a half months. The crystal structure of the p-ZnO films is amorphous with an average transparency of 34.5%.

In this work, we re-evaluate the temperature coefficient in multi-junction solar cells by including the effects of radiative coupling (i.e. re-absorption of emitted photons within the cell) and eliminating radiative losses towards the substrate (i.e. use of a back mirror). The model developed is for two-junction devices, and it takes into account: the number of terminals, the energy bandgaps of the sub-cells, the light concentration, and whether a back mirror is used or not. The temperature coefficients obtained are compared with the case where no luminescent effects are considered. The results show that, in two-terminal and four-terminal devices, the sensitivity to temperature is almost the same whether luminescent effects are taken into account or not. However, these effects are most significant in three-terminal devices. In four-terminal devices, the results show that these effects depend to a large extent on the materials used, the design of the system, i.e. on the effectiveness of radiative exchange between the cells involved.

To better understand the response of oxygen vacancy concentration to applied potential, the lattice parameter of pulsed laser deposited La0.6Sr0.4Co1-xFexO3-δ thin films was monitored using in situ X-ray diffraction. We demonstrate that the chemical expansion under applied potential depends on the cathode morphology, which determines the contribution of different reaction pathways. We investigated applied potential dependent lattice expansion on La0.6Sr0.4Co1-xFexO3-δ with 3 different Co:Fe ratios in an attempt to connect bulk chemical expansion data to thin films. We find that the chemical expansion trends in thin films are different than expected from bulk data.

Graphene possesses excellent mechanical, thermal and electronic properties, not to mention its optical transparency and chemical stability. Much effort has been made towards the control of its physical properties for technological applications. One way to achieve this control is by modifying graphene size and structure. Recently, in a search for the development of semiconducting graphene structures to be produced at large scale, a new structure called graphene nanomesh was synthesized by means of block copolymer lithography and other methods. Basically, a graphene nanomesh is a graphene structure made to possess a periodic array of nanoscale holes whose sizes and hole-to-hole (or neck) distances are considered as control parameters for its overall electronic properties. Although the electronic properties of graphene nanomeshes are being intensively studied, their mechanical properties are still to be investigated. This work, then, presents the first study of mechanical, structural and thermal properties of graphene nanomeshes as a function of hole and neck sizes, through atomistic molecular dynamics simulations. The dependence of the Young’s modulus and coefficient of thermal expansion of graphene nanomeshes on the hole and neck sizes will be shown.

Nanoarchitectures consisting of single crystalline Co3O4 spheres and multi-walled carbon nanotubes (MWCNTs) have been constructed successfully. The effect of reaction temperature on the morphology of the products reveal that the growth rate dictates the shape and size of Co3O4 beads on and around MWCNTs. Single crystalline Co3O4 spheres around MWCNTs can be produced in large scale by elevating reaction temperature for the increased growth rate. The electrochemical properties of the hybrid materials were investigated by cyclic voltammetry (CV) and galvanostatic charge/discharge tests. The supercapacitors made with the nanoarchitectures show high specific capacitance of 445 F/g at a current density of 0.1 A/g and exhibit excellent cycling stability.