In the present study, the sub-gap states of amorphous In-Ga-Zn-O (a-IGZO) thin films treated with various process conditions have been evaluated by means of capacitance-voltage (C-V) characteristics and isothermal capacitance transient spectroscopy (ICTS). It was found that the space-charge densities of the a-IGZO decreased as the oxygen partial pressure was increased during the sputtering of a-IGZO thin films. The ICTS spectra for the 4, 8, and 12 % samples were similar and the peak positions were found to be around 1 × 10-2 s at 180 K. On the other hand, the peak position for the 20 % sample shifted to a longer time regime and was located at around 2 × 10-1 s at 180 K. The total densities of the traps for the 4, 8, and 12 % samples were calculated to be 5−6 × 1016 cm-3, while that for 20 % was one order of magnitude lower than the others. From Thermal desorption spectrometer, it was found that desorption of Zn atoms started at a temperature higher than 300 °C for the 4 % sample, while desorption of Zn was not observed for the 20 % sample. The introduction of the sub-gap states could be attributed to oxygen-rich and/or Zn-deficient defects in the a-IGZO thin films formed during thermal annealing.

We examine a novel phase of the underscreened Anderson lattice Model that might pertain to the ”Hidden Ordered” phase of URu2Si2. We show that the system breaks spin-rotational invariance below the critical temperature and spontaneously selects a preferred axis of spin quantization. As a result, the low temperature phase exhibits a magnetic anisotropy, where the electronic properties depend not only on the magnitude of the magnetic field but also on the orientation of the applied field relative to the axis of quantization. The results are discussed in the context of recent experimental findings on URu2Si2.

In our earlier work [1] microstructural evolution in tungsten under self-ion irradiation was investigated as a function of temperature and dose by in-situ 150 keV W+ ion irradiations on the IVEM-Tandem facility at Argonne National Laboratory (ANL). The present work focuses on the thermal stability of this damage. Thin foils of tungsten were irradiated at room temperature (R.T.) to fluences up to 1018 W+m-2 (∼ 1.0 dpa) and were then annealed in-situ for up to 120 min at temperatures between 300 and 800°C.

We found that: (1) loops with Burgers vectors ½ <111> and <100> coexist during annealing; (2) <100> is not a stable loop configuration above 300°C and the fraction of such loops decreased with increasing temperature and/or time; (3) changes in loop populations during annealing were very sensitive to temperature, but less sensitive to time. The majority of changes occurred within 15 min, and were associated with the loss of small (1-2 nm) dislocation loops. The origin of these trends is discussed by considering defect mobility and the energetics of defect configurations predicted by previous DFT calculations [2].

Laser is used to produce graphene nanoribbons (GNRs) by unzipping carbon nanotubes (CNTs). It is found that laser can not only unzip CNTs, but also join GNRs through covalent reconnections. Because the CNTs are aligned in a freestanding CNT sheet, the laser irradiation process results in a freestanding GNR network. Experimental results show that the expected results can be achieved by controlling the delivery of laser beam energy to the sheet. Moreover, this process is a solid-state process and a scalable manufacturing process.

A new donor-acceptor structured conjugated polymer (PDODTBI) with trifluoromethylated benzimidazole and benzo[1,2-b;3,4-b']dithiophene (BDT) unit have been designed and synthesized using Stille coupling polymerization reaction. The polymer is highly soluble in common organic solvents such as chloroform, tetrahydrofuran and chlorobenzene with good film forming properties. The structure of the polymer is elucidated by 1H NMR and FTIR spectroscopic techniques. The introduction of a trifluoromethyl group at 4th position of the benzimidazole unit has significantly altered the optical and electrochemical properties of polymer. Polymer film showed broad absorption band in the range of 400-680 nm. Optical band gap of the polymer estimated from the absorption band edge and is found to be ∼1.88 eV. Polymer exhibited deeper HOMO (-5.0 eV) and the LUMO (-3.12 eV) energy levels. Bulk heterojunction (BHJ) solar cell device with PDODTBI as a donor and PC61BM as an acceptor were evaluated.

Current treatment options for tissue loss or organ failure include organ/tissue transplantation of autografts/allografts, delivery of bioactive agents, and utilization of synthetic replacements composed of metals, polymers, and ceramics. However each strategy suffers from a number of limitations. The early attempts to overcome these drawbacks led to the emergence of tissue engineering that provided viable tissue substitutes using a combination of biomaterials, cells, and factors. This approach was ideally suited to repair damaged tissues; however the substitution and regeneration of large tissue volumes and multi-level tissues such as complex organ systems require more than optimal combinations of biomaterials and biologics.

‘Regenerative Engineering’ is aimed at creating large and complex tissue systems incorporating advances in material science, stem cell technology and developmental biology. We believe that recent breakthrough technologies in advanced materials science and nanotechnology allow us to recapitulate native tissues. The novel designer polymers incorporate bioactivity and physical features specific to a regeneration application. Overall, engineered materials and scaffolds afford selective control of cell sensitivity, and precise control of temporal and spatial stimulatory cues. We aim to build multi-level systems such as organs through location-specific topographies and physico-chemical cues incorporated into a continuous phase using a combination of classical top-down tissue engineering approach with bottom-up strategies used in regenerative biology.

Musculoskeletal tissues are critical to the normal functioning of an individual and following damage or degeneration show extremely limited endogenous regenerative capacity. The development of material and structural platforms to modulate stem cell behavior to enhance regeneration is an area of great interest. In this manuscript we cover some examples of material development, and incorporation of topographical and cytokine cues to modulate the differentiation of hard and soft musculoskeletal tissues such as bone, ligament and tendon.

For a cost-efficient fabrication of homogeneous oxide thin films the usage of amorphous materials is favorable. They can be deposited at room temperature (RT) and represent an interesting alternative to amorphous silicon in electronics. Zinc-tin oxide is a promising n-type channel material for thin film transistors and consists of abundant elements, only, in contrast to the well-explored indium gallium zinc oxide. Here, the electrical and optical properties of room temperature deposited ZTO thin films are discussed. These films were fabricated via pulsed-laser deposition on glass substrates by ablating a ceramic target composed of ZnO and SnO2 in a 1:2 ratio. The resistivity has been controlled over seven orders of magnitude via the oxygen growth pressure. Further, the optical transmittance tends to be higher for higher oxygen growth pressures.

Cold spray is a novel and promising technology to obtain surface coating. Notwithstanding the several technological advantages with respect to other processes, its diffusion is somewhat limited because of the limited knowledge on the mechanical properties of the cold sprayed materials and in particular, the fatigue behavior. Moreover, the existing data concerning fatigue behavior of coated specimens are controversial and different material system shows different behaviors. The aim of this study is to distinguish the involved parameters and their effect on fatigue behavior of cold sprayed systems. A critical discussion on four important parameters i.e. interface quality, material properties, deposition parameters and residual stress is given. The influential parameters are consolidated in one formula, which can predict the fatigue limit of cold spray system as a function of residual stress, coating hardness and stress gradient in the specimen.

Intermolecular interaction potentials of the acrylamide dimer in 12 equilibrium configurations have been calculated using the second-order Møller-Plesset (MP2) perturbation theory. We have employed Pople’s medium size basis sets [up to 6-311++G(3df,2p)] and Dunning’s correlation consistent basis sets (up to aug-cc-pVTZ). We have also carried out density functional theory (DFT) type calculations and compared the results with those calculated with the MP2 theory.

In the current paper we modify the evolution equations of the simplified continuum dislocation dynamics theory presented in [T. Hochrainer, S. Sandfeld, M. Zaiser, P. Gumbsch, Continuum dislocation dynamics: Towards a physical theory of crystal plasticity. J. Mech. Phys. Solids. (in print)] to account for the nature of the so-called curvature density as a conserved quantity. The derived evolution equations define a dislocation flux based crystal plasticity law, which we present in a fully three-dimensional form. Because the total curvature is a conserved quantity in the theory the time integration of the equations benefit from using conservative numerical schemes. We present a discontinuous Galerkin implementation for integrating the time evolution of the dislocation state and show that this allows simulating the evolution of a single dislocation loop as well as of a distributed loop density on different slip systems.

An electrical and analytical study was carried out to investigate TiW/ZnO Schottky contacts with 30 nm ZnO thin film layers deposited by pulsed laser deposition (PLD), plasma enhanced atomic layer deposition (PEALD), and thermal atomic layer deposition (TALD). Devices with ZnO layer deposited by TALD exhibit approximately linear behavior in their I-V measurements. However, both devices with ZnO layers deposited by PEALD and PLD behaved like Schottky rectifiers with barrier heights between TiW and ZnO of 0.51 eV and 0.45 eV respectively and ideality factors of 2.0 and 2.3 respectively. The PEALD deposited ZnO Schotty diodes demonstrated an on/off rectifying ratio of about 25 at ±1 V. The leakage current values of the PLD deposited ZnO Schottky diodes are significantly larger than those of PEALD, leading to a poor on/off rectifying ratio of ∼4. Due to the small thickness, a critical breakdown strength of 1.3 MV/cm was estimated for PEALD-ZnO thin films.

The organometallic approach was successfully applied to synthesize water-soluble ruthenium nanoparticles displaying interesting catalytic properties in hydrogenation of unsaturated model-substrates. Nanocatalyst synthesis was performed by hydrogenation of the complex [Ru(COD)(COT)] in the presence of sulfonated diphosphines and cyclodextrins as protective agents providing very small ruthenium nanoparticles (ca. 1.2-1.5 nm) with narrow size distribution and high stability. Catalysis results in water evidenced a control of the surface properties of these novel ruthenium nanocatalysts at a supramolecular level.

Non-polar a-plane InGaN films were grown on a r-plane sapphire substrate by plasma assisted molecular beam epitaxy (PAMBE). The growth temperature and Indium flux were varied to optimize the desired composition of In0.23Ga0.77N on the (11-20) a-plane GaN epilayer grown on a (1-102) r-plane sapphire substrate. The structural, morphological and optical properties of the optimized composition have been studied. It was found that highly a-axis oriented InGaN epilayers with no phase separation can be grown at 540 °C with In/Ga flux ratio of 0.72. The composition of indium incorporation in single phase InGaN films was found to be 23% as estimated by high resolution X-ray diffraction. The room temperature band gap energy of single phase InGaN layers was determined by photoluminescence measurement and found to be around 2.56 eV.

We present a comparative density functional theory study of Li, Na, and Mg storage energetics and diffusion in α-Sn, including the effects of temperature (vibrations). We study several concentrations corresponding to initial stages of insertion (number densities x= 1/64, 1/32, 1/16, and 1/8) as well as the final state of charge (Li17Sn4, Na15Sn4, and Mg2Sn). While final states of charge correspond to positive anode voltages for all three types of metal, insertion energetics is favorable for insertion for Li at all concentrations studied, for Na up to the concentration of x = 3/64, and Mg insertion is thermodynamically disfavored at all x. Diffusion barriers at dilute concentrations are computed to be 0.23, 0.51, and 0.44 eV for Li, Na, and Mg, respectively. Vibrations have a noticeable and temperature-, concentration-, and dopant-type dependent effect on voltages, of the order of 0.1 eV at room temperature.

To modify the rigid structure of alginate, polyvinyl alcohol was mixed. Rheological properties and viscoelastic properties of the polymer blend solution were investigated. Complex and shear viscosity and tangent delta of the solution were obtained to find optimum condition of spinning dope. Effect of blend ratio on morphology and property change was investigated.

Electrochemical reduction of CO2 into useful organics combined with photovoltaics is thought to be one of the promising ways to effectively store and transport the solar energy. In most of the previous researches, CO2 bubbling in different solutions were used as the electrolyte. However, the effects of the electrolyte and the CO2 bubbling are not clear. Therefore, in this research, the effects of different electrolyte, CO2 bubbling, concentration of the electrolyte and temperature on the electrochemical reduction of CO2 on a Cu working electrode were studied. The results showed that the form of the carbon source in the electrolyte, such as HCO3 -, CO3 2- and H2CO3, had a strong effect on this reaction, which was controlled by the pH of the electrolyte. Furthermore, high concentration of the HCO3 - and elevated temperature can strongly improve the reaction current density.

Development of effective CO2 separation technologies is one of the most critical issues for implementation of CO2 Capture & Storage (CCS) because CO2 capturing covers about 60 % of the total CCS cost. CO2 capturing with solution absorption technology has gained current acceptance, and the actual operations have been demonstrated in many countries. However, This technology requires certain amount of energy in recovering CO2 from the CO2-capturing solution, which results in developing alternative CO2 capturing technologies. Because difference in partial pressure of the interest gas between feed and permeate side drives the separation, membrane separation does not need additional energy and can make CO2 separation much more effective. ☐In pre-combustion such as an integrated gasification combined cycle (IGCC) plant, CO2/H2 gas mixture after water-gas shift reaction has a pressure of 2.4 MPa, which would be preferable for membrane separation. Various membranes for CO2 separation over H2 have been investigated, however, the membrane separation has not been implemented due to lack in CO2 selectivity or permeability. In this paper, poly(amidoamine) (PAMAM) dendrimer is used to enhance affinity to CO2 and incorporated in a polymer matrix. The resulting polymeric membrane expressed excellent CO2 separation properties even under pressure. The CO2 permeance is relatively lower than the requirement value and 1.0 x 10-10 m3(STP)/(m2 s Pa). However, the permeance can be enhanced by reducing membrane thickness.

Simulation results of InGaN light-emitting diodes and efficiency droop are presented. A special method for investigating the changes in the semiconductor devices characteristics due to different influencing factors is developed.

The cause of efficiency droop was detected-large difference in carrier lifetimes. The simulation results are used to suggest several techniques for improving LED efficiency up to 10-15 %.

ZnO and ZnO/ZnFe2O4 nanocomposites were synthesized by mechanical-assisted thermal decomposition method. The results show that this method is a simple and low cost method to prepare ZnO and ZnO/ ZnFe2O4 nanocomposites. The nanorod's shape and size have been identified through SEM and TEM. The photocatalytic activity of ZnO and ZnO/ZnFe2O4 nanocomposites were tested by the degradation of methylene blue (MB) in aqueous medium under almost-visible light and the efficiency of the catalyst has been discussed in detail.