Metallic nanoparticles under 10 nm are of particular interest for the microelectronics industry. However, there is a lack of convenient synthetic routes to control their size Oxophilic metals, such as Ta, are also of high interest, however, the high oxophilicity and melting point makes the synthesis of such nanoparticles challenging. Making use of imidazolium-based ionic liquids, monodisperse zero-valent tantalum nanoparticles (Ta(0)NPs) have been successfully synthesised at room temperature by reduction of tris(neopentyl)neopentylidenetantalum(V). Furthermore; well size-controlled bimetallic Ru-Ta NPs have also been synthesized.

Polyurethanes (PU) have been widely used as biomaterial in recent years, while thrombus may still occur when contacting with blood especially for extended period of time. Poly(ethylene glycol) (PEG) and phosphorylcholine (PC)-based polymers are commonly employed for surface modification to create protein repellent surfaces. PC-based polymers have been investigated as biomimetic materials because PC is the major component in the outer layer of cell membranes. In this study, the biomimetic copolymer brush of PEG-b-poly(2-methacryloyloxyethyl phosphorylcholine) on PU surfaces was synthesized via atom transfer radical polymerization (ATRP) with a surface initiator. The flexible PEG chain was 200 g·mol-1, while the poly(2-methacryloyloxyethyl phosphorylcholine) (poly(MPC)) chain length was controlled by the ratio of monomer to sacrificial initiator in solution. The topology of the modified surfaces was characterized by the phase image of atomic force microscopy (AFM) to study the synergy effect between PEG chains and poly(MPC) chains. The unmodified and modified surfaces were characterized by Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), water contact angle and platelet adhesion. The results demonstrated that efficient grafting of PEG-b-poly(MPC) brushes on the surfaces was achieved. The PU surfaces modified with PEG and phosphorylcholine zwitterionic brushes showed effective resistance to platelet adhesion and high hemocompatibility in vitro. These PEG and PC-grafted PU materials might be potentially applied in blood-contacting materials or devices due to their good mechanical and hemocompatible properties.

Transparent conductive oxides, gallium-doped zinc oxide (ZnO:Ga) and tin-doped indium oxide (ITO), were fabricated by a solution-based ultrasonic spray-assisted mist deposition technique. The ZnO:Ga films showed a good c-axis orientation perpendicular to the substrate and achieved low resistivity of 2.3 × 10-3 Ω cm with high transmittance in wide wavelength region. ITO films have lower resistivity of 1.4 × 10-4 Ω cm and high transmittance over the wavelength of 300 nm.

This work presents a study on the activation behavior of high-dose (φ > 1015 cm-2) boron and phosphorus implants for low resistance source and drain regions for thin-film transistors (TFTs) fabricated using solid-phase crystallization (SPC) of amorphous silicon. Process variables include factors associated with ion implant and annealing conditions, as well as the SPC and implant process arrangement. Four-point probe sheet resistance (Rs) measurements were used as a comprehensive assessment of the electrical properties. Results have identified similarities and differences in activation behavior that can influence process integration strategies considering both the SPC approach and TFT fabrication.

Torsion experiments on 50μm diameter Cu wires are reported, using the load/unload method and a gauge length of 1m to obtain torsional strain sensitivity better than unity microstrain. The experiments are able to resolve reversible and irreversible deformation at such very low strains. Plastic deformation, dislocation creep and the Bauschinger effect are easily observed at room temperature and at about 300°C, both in the low-strain regime where it is unlikely that dislocation sources are activated, and at higher plastic strain.

The thermoelectric properties of Bi-FeSb2 nanocomposites are reported. The electrical resistivity and the Seebeck coefficient measurements show a significant dependence on bismuth concentration. Our results reveal that the shifting of the Seebeck peak in FeSb2 nanocomposites is purely a grain size-effect. The thermal conductivity data indicates a presence of an electron-phonon interaction. Over all, our analysis of the the thermoelectric properties of Bi-FeSb2 nanocomposites provide additional evidence for phonon-drag in FeSb2.

A high modulus, sulfonated polymer synthesized from one-to-one ratio 4,6-bis(4-hydroxyphenyl)-N, N-diphenyl-1,3,5-triazin-2-amine and 4,4′-biphenol with bis(4-fluorophenyl) sulfone (DPA-PS:BP) is exploited as an ionomer for micro-ionic actuators. A unique and attractive feature of the ionomer is that it can contain high amounts of ionic liquid (IL) as an electrolyte while maintaining a high elastic modulus (i.e 600 MPa for 150 wt% uptake), which is more than one order of magnitude higher than the state-of-the-art of ionomers with working electrolytes. Such a high modulus makes it possible for the ionomer to be fabricated into micro-actuators with high uptake of ILs and low operation voltage (< 4 V), in various free standing forms with ion milling techniques, which are attractive for MEMS applications. As an initial demonstration of a DPA-PS:BP based ionic micro-actuator, a cantilever (200 μm x 33 μm x 5 μm) is manufactured by Focused Ion Beam (FIB) and characterized. Under the voltage of 1.6 V, the bending actuator exhibits an intrinsic strain from the active ionomer of 1.1% and a corresponding blocking force of 27 μN.

In the past few years, organic vapor phase deposition (OVPD) has been demonstrated to be an effective deposition method for high-performance monochrome and white organic light emitting diodes (OLEDs) [1-4]. OVPD provides good material utilization efficiency and large achievable deposition rates.

An application of p-type doping is the improvement of hole injection either from the anode contact or from a charge generation layer in stacked OLEDs [5]. Nevertheless, no reports on p-type doping using OVPD can be found in literature, in part due to the thermal instability and high chemical sensitivity of organic dopants.

In this work, p-type doping using an AIXTRON Gen-1 OVPD tool with two different show-erhead designs is examined. NDP-2 (NOVALED) and N,N‘-diphenyl-N,N‘-bis(1-naphthylphenyl)-1,1‘-biphenyl-4,4‘-diamine (NPB) were used as p-type dopant (guest) and hole-conducting host, respectively. p-Type doped hole-only devices were fabricated and compared with undoped ones.

Two different showerhead designs (made either of aluminum or stainless steel) were investi-gated with respect to OLED performance to determine possible side reactions.

Highly efficient monochrome red OLEDs including a p-type doped hole transport layer were demonstrated exhibiting a current efficiency of 31 cd/A, a power efficiency of 26 lm/W and a driving voltage of 3.7 V without improved light outcoupling (all values at 1000 cd/m2).

Nanowires with different nitrogen concentrations were grown by Metal-Organic Chemical Vapor Deposition (MOCVD) using DEZn, N2O and NH3as zinc, oxygen and nitrogen doping sources respectively. Low temperature photoluminescence, Raman spectroscopy and Transmission Electron Microscopy are combined to study the incorporation of nitrogen in the wires. The observation of donor-acceptor pair band confirms that the incorporation nitrogen in ZnO nanowires is responsible for the creation of acceptor centers. The additional peaks observed in Raman are correlated to nano-sized inter-atomic distance fluctuations observed in TEM. These domains combined with a resonance effect are probably the explanation of the huge Raman cross section observed for the impurity related peaks.

The combined application of section and projection topography carried out using synchrotron white beam radiation can be a powerful tool for the determination of the three-dimensional configurations of defects in single crystals. In this paper, we present examples of the application of this combination of techniques to the analysis of defect configurations in PVT-grown 4H-SiC wafers cut perpendicular and parallel to the growth axis. Detailed correlation between section and projection topography of threading screw dislocations (TSDs) is presented with particular emphasis being laid on the determination of the signs of the dislocations. Further, information can also be determined regarding the position of the dislocations within the crystal depth. In addition, similar correlation is presented for threading edge dislocations (TEDs) and basal plane dislocations (BPDs). The section topography images of dislocations can comprise direct, intermediary and dynamical contrast and all three types are observed. The application to the study of stacking faults will be also discussed in detail.

The formation and strength of dislocations in the hexagonal closed-packed material are studied through dislocation junctions and the critical stress required to completely break them. Dislocation dynamics calculations of junctions are compared to an analytical line tension approximation in order to verify the simulations. Results show agreements between the models. Also the critical shear stress necessary to break a short and a long dislocation junction is computed numerically. Unzipping envelopes are mapped out for these junctions to describe their stability regions as functions of resolved shear stresses on the glide planes. The example of two non-coplanar binary dislocation junctions with slip systems [2 -1 -1 0] (0 1 -1 0) and [-1 2 -1 0] (0 0 0 1) corresponding to a prismatic and basal slip respectively is chosen to verify and validate our implementation.

The low temperature solution based transformation of silver metal layers to II-VI materials is investigated as an alternative mechanism for forming semiconductor thin films. This metal to semiconductor conversion has been demonstrated with the solution based sulfurization and ion exchange of silver nanoparticles, but not to our knowledge on thin films. Starting with metal films is attractive because they may be scalably deposited on many substrates through evaporation or electro- and electroless plating. The metal to II-VI transformation is challenging in films because diffusion occurs directionally and because the ∼40% increase in lattice expansion may cause debonding. Silver films were deposited on glass with Ti adhesion layers and successfully transformed to well-adhered CdS and MnS films at ≤ 60 ºC. The II-VI compounds were confirmed by XRD and shown to be polycrystalline with SEM. Electrical conductivities, bandgaps, and optical absorption spectra were measured. These results demonstrate that solution based sulfurization and ion-exchange is a viable mechanism for forming II-VI semiconductor thin films with good conductivities from metal films at low temperatures.

Human mesenchymal stem cells (hMSCs) were routinely cultured on tissue-culture polystyrene (TCPS) to investigate the in vitro aging and cell stiffening. hMSCs were also cultured on thermoplastic polyurethane (TPU), which is a biocompatible polymer with an elastic modulus of approximately 12.9MPa, to investigate the impact of substrate elastic modulus on cell stiffening and differentiation potential. Cells were passaged over several generations on each material. At each passage, cells were subjected to osteogenic and myogenic differentiation. Local cell elastic modulus was measured at every passage using atomic force microscopy (AFM) indentation. Gene and protein expression was examined using qRT-PCR and immunofluorescent staining, respectively, for osteogenic and myogenic markers. Results show that the success of myogenic differentiation is highly reliant on the elastic modulus of the undifferentiated cells. The success of osteogenic differentiations is most likely somewhat dependent on the cell elastic modulus, as differentiations were more successful in earlier passages, when cells were softer.

As a novel biomimetic polymer gel, we have been studying polymer gels with an autonomous self-oscillating function, since firstly reported in 1996. For developing the polymer gels, we utilized oscillating chemical reaction, called the Belousov-Zhabotinsky (BZ) reaction, which is recognized as a chemical model for understanding several autonomous phenomena in biological systems. The self-oscillating polymer gel is composed of a poly(N-isopropylacrylamide) network in which the metal catalyst for the BZ reaction is covalently immobilized. Under the coexistence of the reactants, the polymer undergoes spontaneous swelling-deswelling changes (in the case of gel) or cyclic soluble-insoluble changes (in the case of an uncrosslinked polymer) without any on-off switching of external stimuli. Several kinds of functional material systems utilizing self-oscillating polymers and gels such as biomimetic actuators, mass transport surface, etc. are expected. Here recent progress on self-oscillating polymers and gels and the design of functional material systems are summarized.

Thin films of SnO2 were prepared via wet chemical method and deposited by dip-coating on glass substrate. The annealing temperatures of the samples were 300, 400, 500 and 600o C, respectively. Water vapor sensor responses were measured and the experimental results are tested using the Freundlich model. The better water vapor sensitivities were obtained for annealing temperatures of 500 and 600oC, respectively. The samples were characterized morphological and structurally by SEM, XRD, Mössbauer spectroscopy and Raman spectroscopy. The fringes features in the ultraviolet-visible region indicate films thickness around 370 nm. The results are discussed in terms of the fine grain size of the samples.

The present work reports on the effect of hydrogen on mechanical properties of aluminum AA 6061 hardened by precipitation. Test specimens are solution treated in an electric induction furnace at 803 K during 1 hour and then precipitation hardened during 4 hours at 423, 448 and 473 K. The heat treated specimens are subjected to a hydrogen cathodic charging process during 0, 24 and 96 hours and then tested under monotonic uniaxial tensile loading according to ASTM E8-03. Scanning electron microscopy characterization of tensile fracture surfaces reveals that hydrogen charging of precipitation hardened specimens enhances intergranular cracking by microvoid coalescence and intragranular cleavage fracture. The results show that, although hydrogen charging causes embrittlement of precipitation hardened aluminum AA 6061, the effect is a function of time; short time cathodic charging increases the ductility of the alloy.

Gold species on an oxide support possess variable electronic structures via charge transition so as to increase their chemical redox activity. They are also viably promising for use to enhance gas-sensing response when being exploited in a solid state gas sensor. The synthesis method of the gold-loaded materials plays a crucial role in the functionality. In this paper, we report two types of gold/tin oxide based nanopowders prepared by co-precipitation method and by deposition-precipitation method, respectively. They were evaluated as sensing elements in a semiconductor carbon monoxide (CO) gas sensor. Effects of the material type and CO concentration on sensor response were investigated. Their structural characterizations were done by X-ray photoelectron spectroscopy, X-ray diffraction and transmission electron microscopy. Results demonstrate the surface gold species effective to facilitate CO oxidation in gas atmosphere and promote low-temperature sensor performance.

The nanoencapsulation in biocompatible inorganic materials with human cell activity is a leading technology to control the process of releasing the drug in the right place. At present, the sol-gel process has emerged as a promising platform for the immobilization, stabilization and encapsulation of biological molecules such as enzymes, antibodies, microorganisms, and a variety of drugs. The matrices obtained are chemically inert, hydrophilic and easy synthesis. They have high mechanical strength, thermal stability in wide temperature ranges and absorb organic solvents so insignificant compared with other organic polymers. They are resistant to microbial attack and exhibit high biocompatibility with the body, as provided for implantation in situ in the treatment of various diseases. An additional advantage is that it provides viability encapsulated molecules, since these matrices act as reservoirs of water thus helping to maintain the biological activity of enzymes, antibodies, cells, and drugs for the moisture level required for the molecule. We used the action of the active ingredients of tepezcohuite (condensed tannins) to assess the capacity aseptic surgical wound healing than 1 cm in diameter in New Zealand white rabbits. Experimentally and statistically demonstrating the effectiveness of healing nanoreservoirs Tan/TiO2-150 the weight of tannins by 60% compared to condensed tannins as such, TiO2and isotonic saline.

Polymeric materials are widely used in power generation and energy storage applications. Deoxyribonucleic acid (DNA) biopolymer-based hybrids have been found to display interesting electrical characteristics, such as a relatively high dielectric constant, good resistivity and dielectric breakdown behavior, and are promising as insulating dielectrics for capacitor applications. This research describes the processing, test structure design, and electrical characterization of DNA-sol-gel hybrids for energy storage applications.