Chondroitin sulfate (CS) is one of the major glycosaminoglycans (GAGs) present in the connective tissue extracellular matrix (ECM) and is responsible for the regulation of cellular activities as well as providing mechanical support for the surrounding tissue. Due to presence of CS in the natural tissues including cartilage, hydrogels of CS and other GAGs have been widely used in cartilage regeneration. Due to their polyelectrolyte nature, GAG-based hydrogels are brittle and require modifications to overcome the weak mechanical properties. In this work, we showed copolymerization of methacrylated chondroitin sulfate with oligo(ethylene glycol)s improved the crosslink density of the gels from 2 to 20 times depending on the methacrylation degree of CS and length of the crosslinking monomer. Copolymerization of CS with oligo(ethylene glycol) acrylates is a method to design hydrogels with tunable swelling and mechanical properties.

The improvement of concrete workability can provide a considerable reduction of production expenses and also leads to significant improvement of construction quality. This paper reports on the development of self-consolidating concrete (SCC) based on local materials, such as metakaolin (MK) and aggregate fines. The use of metakaolin in SCC is found to be very promising, due to its ability to increase the flowability and segregation resistance of concrete mixtures. Furthermore, due to pozzolanic properties, the application of MK provides an improvement of concrete microstructure, strength and durability. The proposed SCC design includes the optimization of aggregates and combined aggregate-binder powders to target 0.45- and 0.3- power particle size distributions, respectively.

Hydroxyapatite-chondroitin sulfate (HAp/ChS) composites were synthesized with calcium hydroxide suspension and phosphoric acid solution containing ChS through a precipitation method, and the microparticles were then fabricated by a spray dry method with the suspension of the composites. Bovine serum albumin (BSA) with negative charge or lysozyme (LYZ) with positive charge at pH7.0 was adsorbed onto the HAp/ChS microparticles. However, the HAp/ChS microparticles adsorbed LYZ more than the HAp microparticles compared with BSA due to the electrostatic interaction from negatively-charged sulfate or carboxyl group of ChS in the composites. The release property of BSA from the HAp/ChS microparticles was evaluated in Dulbecco’s phosphate buffered saline (pH7.2). The HAp/ChS microparticles released quickly 100% of the adsorbed BSA, while HAp microparticles released 45% of BSA. These results indicated that incorporation of ChS in the microparticles controls the adsorption and release properties of protein due to the electrostatic interaction. The HAp/ChS microparticles therefore are a candidate of a carrier for drugs like vaccines.

Electrical performance and reliability of SiC Junction Transistors (SJTs) and Schottky rectifiers are presented. The 650 V/50 A-rated SiC SJTs feature current gains (β) up to 110 at room-temperature, 70 at 250°C, and stable breakdown characteristics. Single current pulse measurements indicate an almost invariant β up to 800 A/cm2 at 175°C – a measure of the SOA boundary for pulsed current SJT operation. Lower than 5 mA/cm2 leakage currents are measured on the SJTs at the rated blocking voltage and at 250°C. 1200 V Schottky rectifiers designed for high-temperature operation display < 3 mA/cm2 leakage currents up to 250°C. A 10x reduction in leakage current and 23% reduction in junction capacitance are observed when compared to the nearest competitor. The high-temperature Schottky rectifiers and SJTs display stable breakdown voltages and on-state characteristics after long-term HTRB stressing. A significant improvement in current gain stability is achieved by fine-tuning the fabrication process.

Nanowire heterostructures comprised of cobalt oxide and tungsten oxide were fabricated in a core/shell configuration. This was achieved by sputter coating tungsten oxide shells on standing cobalt oxide nanowires on a substrate. To ensure the polycrystallinity of tungsten oxide shell, the nanowire heterostructures were subjected to post-sputtering annealing process. The cobalt oxide nanowires for this study were grown employing a thermal method via vapor-solid growth mechanism. The crystal structures, morphologies, dimensions, and phases at various growth stages of nanowire heterostructures were studied using high resolution electron microscopy, energy dispersive spectroscopy, and X-ray diffraction methods. The interfaces of these nanowire heterostructures were also studied and showed variation in the lattice spacing across the heterostructure diameter. Results indicated that the cobalt oxide nanowires survived multiple processing steps and resulted in stable heterostructure configurations. The investigation shows, for the first time, a dry processing route for the formation of such novel nanowire heterostructures.

This work presents a systematic rheological study of the gelatinization process of corn-starch plasticized with glycerol, showing the effects of the glycerol/starch ratio, water/starch ratio, and clay (montmorillonite) content. Gelatinization temperatures at different heating rates in rheological oscillatory temperature-sweep experiments were determined for different corn-starch/glycerol/clay formulations. The influences of the different formulation variables on the gelatinization processes and on the gel properties are analyzed. Some hypotheses postulating how the different intermolecular interactions present in the composites are responsible for these effects are discussed.

A mathematical model is developed to describe deoxidation of water in a physical model of a batch aluminum degassing reactor equipped with the rotor-injector technique, assuming that deoxidation kinetics of water is similar to dehydrogenization of liquid aluminum. Degassing kinetics is described by using mass transport and mass balance principles by assuming that degassing kinetics can be characterized by a mass transfer coefficient, which depends on the process variables. The transport coefficient and the average bubble diameter are estimated with correlations reported in the literature for similar gas-injection systems. The water physical model helped to validate the mathematical model and to perform a process analysis by varying: 1) Gas flow rate (20 and 40 l/min); and 2) Impeller’s angular velocity (290 and 573 rpm). Results from the model agree well with measurements of deoxidation kinetics at low impeller rotating speeds. At high rotating speeds the model is still valid but less reliable because it does not take into account the formation of the vortex at the free surface. Nevertheless, the model provides predictions of the influence of every operating parameter and it can be used as a good approximation for real systems.

Oxide thin films of zinc and titanium materials were deposited by different deposition techniques, to be applied as sensitive layers of pH sensor – EGFET device. The deposition techniques tested were dip-coat, spin-coat, electrodeposition and spray-pyrolysis. The routine and the parameters of each technique were changed aiming optimized the procedures. The pHs buffer solutions tested ranged from 2 to 12. ZnO thin film shows sensitivity about 23 mV/pH, while TiO2 thin films shows only 13.8 mV/pH. The final purpose of this study is to optimize the parameters for each deposition technique for both oxide materials.

Methods of improving low-cost Cu2O|ZnO heterojunction diodes fabricated through galvanostatic deposition of Cu2O are presented. Improved processing parameters responsible for maximizing built-in voltage (Vbi) are determined. The relationship between pH, deposition current, temperature, and diode quality is analyzed and a process window for optimal Cu2O deposition on ZnO is obtained with a pH range between 12.0 and 12.1 and a current density range which is determined by the effect of both pH and deposition current (Jdep) on grain size. The pH window is found to be narrower than previously reported1 and much narrower than the processing window for the deposition of Cu2O films. A two-step approach deposition based on the use of different Jdep is presented for the first time. A Vbi of 0.6 V is achieved, which is the highest reported for cells produced using low temperature processing routes involving electrodeposition and reactive sputtering.

We apply a living polymerization theory to describe cooperative string-like particle rearrangement clusters observed in simulations of a coarse-grained polymer melt. The theory quantitatively describes the interrelation between the average string length L, configurational entropy S conf, and the order parameter for string assembly Φ without free parameters. Combining this theory with the Adam-Gibbs (AG) model allows us to predict the relaxation time τ in a lower temperature T range than accessible by current simulations. In particular, the combined theories suggest a return to Arrhenius behavior near T g and a low T residual entropy, thus avoiding a Kauzmann ‘entropy crisis’.

A number of drug carrier systems such as liposomes, polymeric-nanoparticles, microparticles, polymeric micelles have been investigated for intracellular delivery. Among these liposomes are the potential drug vehicles for efficient cytosolic delivery. They have an adhesive property for cell membrane to encapsulate the drug or protein effectively and showing the enhanced absorption rate. One of the problems could be the difficulty of incorporation of the drug or protein into cell. Therefore many studies of the drug carriers have been developed to enhance the intracellular delivery of materials. Here we propose the novel method to improve the intracellular uptaking by using freeze concentration. Solutes are excluded from ice crystallization and concentrated in the remaining solution during freezing by freezing concentration. We have reported that polymeric cryoprotectant which is carboxylated poly-L-lysine was adsorbed on to the cell membrane during freezing and caused effective freeze concentration. In this study we investigated that delivery of protein effectively taking place by liposome as a carrier agent. It was successfully delivered protein to L929 cells via freeze concentration using polymeric cryoprotectant as a novel drug delivery.

We have studied the electrochemical reduction of CO2 using Cu2O nanoparticles deposited on planar electrodes. Nanoparticles are prepared in aqueous solution by chemical reduction of CuCl2 using ascorbic acid with polyethylene glycol surfactant. The particles are then re-suspended in ethanol with added Nafion binder and brush-coated onto glassy carbon substrates. The CO2 electroreduction activity is measured in KHCO3 electrolyte under flowing CO2 using a two-compartment electrochemical cell. Product formation rates are determined using gas chromatography; major gas phase products include CO, H2, C2H4, and CH4, while liquid phase products include C2H5OH and 1-C3H5OH. The observed product distribution agrees with results obtained previously using similar Cu2O particles deposited on carbon fiber paper supports, as well as Cu2O catalysts prepared by electrodeposition or thermal oxidation. In particular, the catalysts produce a much higher ratio of C2H4 to CH4 than observed using polycrystalline Cu foil. The potential dependence of the formation rates for hydrocarbon and alcohol products is roughly two times greater than for H2 and CO formation. Both XRD and SEM measurements confirm the Cu2O nanoparticles undergo at least partial reduction to Cu metal under CO2 reduction conditions, accompanied by significant surface morphological changes. Thus the kinetic results are consistent with current models that the increased C2H4/CH4 ratio is due to the presence of a more open atomic structure on the freshly reduced Cu surfaces.

Excitation of multiple Er3+ ions upon absorption of a single high-energy photon increases Er-related emission at 1.5 μm, and therefore enhances UV/visible-to-IR photon conversion efficiency. Here we investigate this effect for layers of Er-doped SiO2 sensitized with silicon nanocrystals by measuring the quantum yield of 1.5 µm Er-related emission. We demonstrate dramatic increase of the emission commencing for excitation energies above a certain threshold value, as the number of Er3+ ions excited upon absorption of a single incoming photon increases. By comparing differently prepared materials, we show that the actual value of this threshold energy and the rate of the observed increase of the quantum yield depend on sample characteristics – the size of Si nanocrystals and the ratio of Er3+ ions and nanocrystals concentrations.

In this paper we experimentally demonstrate the use of near-ultraviolet steady state illumination to increase the spectral sensitivity of a double a-SiC/Si pi’n/pin photodiode beyond the visible spectrum (400 nm-880 nm). The concept is extended to implement a one by four wavelength division multiplexer with channel separation in the visible/near infrared range. Optoelectronic characterization of the device is presented and shows the feasibility of tailoring the wavelength and bandwidth of a polychromatic mixture. Several monochromatic pulsed lights in the VIS/NIR range, separately or in a polychromatic mixture illuminated the device. Independent tuning of the wavelengths is performed by steady state 390 nm optical bias superimposed from front and back sides. Results show that, front background enhances the light-to-dark sensitivity of the medium, long and infrared wavelength channels, and quench strongly the shorter wavelengths. Back background has the opposite effect; it only enhances the channel magnitude in short wavelength range and strongly reduces it in the long ones. This nonlinearity provides the possibility for selective tuning a specific wavelength. A capacitive optoelectronic model supports the experimental results. A numerical simulation is presented.

Raman scattering of Si nanowires (NWs) presents antenna effects. The electromagnetic resonance depends on the electromagnetic coupling of the system laser/NW/substrate. The antenna effect of the Raman signal was measured in individual NWs deposited on different substrates, and also free standing NWs in air. The one phonon Raman band in NWs can reach high intensities depending on the system configuration; values of Raman intensity per unit volume more than a few hundred times with respect to bulk substrate can be obtained.

We present a physically justified formalism for the calculation of defect formation energies in UO2. The accessible ranges of chemical potentials of the two components U and O are calculated using the U-O experimental phase diagram and a constraint on the formation energies of vacancies. We then apply this formalism to the DFT+U investigation of the monovacancies and monointerstitials in UO2.

The results of the most stable charge states of these defects are consistent with a strongly ionic system. Calculations predict similarly low formation energies for $V_U^{4 - }$ and $I_O^{2 - }$ in hyperstoichiometric UO2.

Osteochondral (OC) tissue is comprised of articular cartilage, the subchondral bone and the central cartilage-bone interface. To facilitate proper regeneration, an equally complex and multiphasic matrix must be used. Although mono-phasic and bi-phasic matrices were previously applied, they failed to establish the OC interface upon regeneration. In this study, we designed and developed a novel matrix with increasing pore volume from one end to other, along the matrix length. For this matrix polylactide-co-glycolide (PLGA) 85:15 microspheres were combined with a water-soluble porogen in a layer-by-layer fashion and thermally sintered. The resulting matrix was then porogen-leached to form a gradiently-porous structured matrix. The formation of this gradient pore structure was established using Micro-Computed Tomography (μCT) scanning. A biodegradable hydrogel was infiltrated into the structure to form a unique OC matrix where the microsphere and hydrogel phases co-exist with opposing gradients. When the individual phases are associated with osteogenic and chondrogenic growth factors, the structureinduced factor delivery might provide the spatially controlled factor delivery necessary to regenerate osteochondral tissue structure. Overall, we designed a gradient matrix system that is expected to support osteochondral tissue engineering while forming a seamless interface between the cartilage and the bone matrix.

Solute trapping of vacancies in a Ni host lattice is a first step to understanding how solute additions may effect ordering phase transformation in Ni-based alloys. Minor additions of solutes (<3 wt.%) may not have an appreciable effect on the thermodynamics of phase stability but strong binding between the vacancy and solute may significantly alter the kinetics of phase transformations. In this work vacancy-solute binding energies are calculated for multiple elements (Cr, Fe, Mn, Si, Ti, Nb, Ta, Cu, Al, Mo) in a pure Ni face-centered cubic lattice. These elements are common in corrosion-resistant Ni-based alloys. Binding enthalpies for the first four nearest-neighbor vacancy-solute pairs are reported for all elements. The results of this study show that Si, Ti, Nb and Ta bind to vacancies in the first nearest-neighbor position. Alloys containing these solute additions may experience delayed phase transformation due to vacancy trapping that slows diffusion.

Two n+-i-p 6H-SiC diode families with P+ ion implanted emitter have been processed with all identical steps except the post implantation annealing: 1300°C/20min without C-cap has been compared with 1950°C/10min with C-cap. The analysis of the temperature dependence of the reverse current at low voltage (-100V) in the temperature range 27-290°C shows the dominance of a periphery current which is due to generation centers with number and activation energy dependent on the post implantation annealing process. The analysis of the temperature dependence of the forward current shows two ideality factor n region, one with n = 1.9/2 at low voltage and the other one with 1 < n < 2 without passing through 1 for increasing voltages. For both the diode families the current with n = 1.9/2 is a periphery current due to recombination centers with a thermal activation energy near the 6H-SiC mid gap. In the forward current region of 1 < n < 2, the two diode families show different ideality factor values which could be attributed to a different post implantation annealing defect activation.