Graphene oxide (GO) is one of the most attractive inorganic nanofillers in proton exchange membranes (PEMs) for its large specific surface area and high proton conductivity. The proton conductivity of GO nanosheet is known to be orders of magnitude greater than the bulk GO, thus it is essential to improve the dispersion of GO nanosheets in the PEM matrix to achieve higher conductivity. In this study, we report a facile and effective method to fabricate a GO/sulfonated poly ether ether ketone (SPEEK) composite membrane with well-dispersed GO nanosheets in SPEEK matrix by using electrospinning technique for direct methanol fuel cell application. The composite membrane exhibits improved proton conductivity, dimensional stability and methanol barrier property due to the presence of well-dispersed GOs. It is believed that the GO nanosheets can not only induce continuous channels for proton-conducting via Grotthuss mechanism, but also act as methanol barriers to hinder the methanol molecules from passing through the membrane.

It has been shown in previous studies that a miscibility gap exists in the hypo-stoichiometric region UO2-PuO2-Pu2O3 with one phase poor in oxygen, and the other with an O/M (Oxygen to Metal ratio) close to 2.00. Data on the evolution of this region in temperature, especially in the vicinity of the oxygen content corresponding to the highest temperature at which the gap can be observed, is scarce. A high temperature X-ray diffractometer with a dedicated gas control setup was used to study the described region in-situ. We have observed reflections of the two cubic phases, with one increasing and the other decreasing in intensity during the thermal plateaus lasting up to 20 h. We compare the calculated lattice parameters with literature. We estimated the O/M evolution of our samples from a comparison of phase fractions values obtained by Rietveld refinement and calculations using the Calphad method.

Shape memory alloys are functional materials that can recover plastic strains between 2 and 6%. This property can be used to produce actuators for many areas as medicine, robotic, aeronautic and others. Recently, it has been observed the particular interest for shape memory alloys welding, especially to obtain Ni-Ti similar and dissimilar joints and fabricate simple or complex structures. In this sense, this work present an experimental study of tungsten inert gas pulsed welding applied to Ni-Ti shape memory alloy wires with 0.9 mm in diameter, previously heat treated at 450 °C for 20 minutes and air cooled. For that, it was carried out tensile tests at isothermal temperatures from 40 °C to 90 °C (steps of 10 °C) for welded and unwelded wires. The transformation temperatures obtained from differential scanning calorimetry were compared to verify the effect of welding process. It was also performed a stabilization process by mechanical cycling in some welded and unwelded Ni-Ti wires. The results showed a low strength and strain capacity of the weld joint at higher temperatures. Although, at lowest temperature, close to 40 °C, it was observed higher values of maximum stress and strain for welded Ni-Ti wires.

Nano-sized SiOx/C composite was successfully prepared by drip combustion in a fluidized bed reactor. A mixture of tetraethyl orthosilicate (TEOS) ant kerosene at a 2:3 volume ratio was used as a precursor solution. The synthesis was carried out between 600 °C and 900 °C. The as-prepared powder (600 °C) consists of SiOx and carbon particles which are approximately ranged from 30 to 80 nm. For the nano-sized SiOx/C composite sample, the heat treatment process was introduced to remove incomplete combustion materials and the dry ball milling was performed to homogenize the distribution of carbon inside the sample. The final sample (nano-sized SiOx/C nanocomposite) was used as an electrode active material and then electrochemical testing was performed. The cell exhibited discharge and charge capacities of 1158 and 533 mAh g-1, respectively, at current density of 50 mAh g-1 in the voltage range between 0.01-3 V versus Li/Li+.

The addition of a CdMgTe (CMT) layer at the back of a CdTe solar cell should improve its performance by reflecting both photoelectrons and forward-current electrons away from the rear surface. Higher collection of photoelectrons will increase the cell’s current, and reduction of forward current will increase its voltage. To achieve electron reflection, conformal CMT layers were deposited at the back of CdTe cells, and a variety of measurements including performance curves, transmission electron microscopy, x-ray photoelectron spectroscopy, and energy-dispersive x-ray spectroscopy were performed. Oxidation of magnesium in the CMT layer was addressed by adding a CdTe capping layer. MgCl2 passivation was substituted for CdCl2 in some cases, but little difference was seen.

A micro-sized fracture testing method has been applied to investigate fracture toughness of alpha-Nb5Si3. Chevron-notched single crystal specimens with a size of 3 x 3 x 15 μm3 were prepared in a grain of polycrystalline alpha-Nb5Si3 by focused ion beam, FIB, technique. Fracture tests were conducted using a nanoindenter at room temperature and linear load-displacement curves and smooth fracture surfaces were obtained. This fracture behavior was presumed to be brittle fracture similar to bulk alpha-Nb5Si3. The average of fracture toughness K Q is 3.45 ± 0.29 MPa√m under a small-scale yielding condition.

To decrease the amount of precious metal usage for Pd-catalyzed aerobic alcohol oxidation, various amount of Cu-contained Pd bimetallic nanoparticle-supported solid base hydrotalcite catalyst (Pdx Cuy -PVP/HTs) were prepared and applied for aerobic benzyl alcohol oxidation. It was found that the addition of Cu atoms into Pd in the range of 0-40% provided a similar or a little superior activity to that of Pd100-PVP catalyst, whereas a large quantity of co-existence Cu (>40%) gradually decreased their activity of the catalyst. The aerobic benzyl alcohol oxidation over Pd80Cu20-PVP/HT served 77% yield and 95% selectivity towards benzaldehyde at 313 K for 5 h in toluene under O2 flow. X-ray adsorption spectroscopy (XAS) studies and scanning transmission electron microscopy-high angle annuar dark field (STEM-HAADF) with energy dispersive X-ray spectroscopy (EDS) analyses suggested that Cu atoms doping into Pd(0) NP influenced not only localized nanostructure but also oxidation state around Pd atoms. We suggested that substitution of precious metal with small amount of transition metals such as Cu lead to geometric/electronic changes in active sites would be one of nice strategies for reducing the cost for the catalyst in the oxidation process.

Thin films of Polyvinylidene Fluoride (PVDF) copolymers have been incorporated within ferroelectric field effect transistors, all organic thin film transistor devices (OTFTs), piezoelectric actuators, and recently proposed as the ferroelectric layer in a promising multiferroic tunnel junction configuration [1]. The properties of most of these devices would benefit from reduced thickness and better thickness control of the ferroelectric layer during device processing.

A proven means for fabricating ultrathin films of the PVDF copolymer is the Langmuir-Blodgett (LB) technique. This technique involves dissolving the polymer in a volatile solvent which is then dispersed dropwise onto a purified water subphase, leaving an ultrathin layer of the copolymer on the water surface. The ability to control the thickness on the molecular level is the most prominent feature of this technique.

In some early studies [2], the minimum thickness of these films was found to be about 5 Angstroms, or roughly the same thickness as the intermolecular spacing of the all-trans β phase for the ferroelectric polymers. Later studies have led to the fabrication of films composed of thicker transfer steps: ∼ 1.8 nm per deposition [3]. The discrepancy is likely explained by the nature of the VDF molecule: it is not an amphiphile.

In this study, we further investigate the properties of Langmuir films of ferroelectric copolymers and discuss the observation of an apparent monolayer phase transition based on abrupt changes observed in the compressibility of the films. The main goal of this project is to discover the extent to which the device properties (like transfer step thickness) of PVDF films can be modified through processing conditions.

Here, we show results on the deposition of ZnO:Al thin films by the successive ionic layer adsorption and reaction method. The growing of the films was performed by sequentially immersing glass and SiO2/Si substrates in water at temperatures close to the boiling point, a precursor reaction solution, water at room temperature and ultrasonic water bath. The resulting ZnO:Al films were transparent and well adhered to the substrates. From X-ray diffraction analysis was determined that the ZnO:Al films had hexagonal wurtzite structure with preferential orientation along the c-axis. Changes in the morphology of the films were obtained from ellipsoidal-shaped aggregates for the undoped ZnO films to spherical-shaped aggregates for the ZnO:Al films. The optical transparency and bandgap of the ZnO:Al films was about 85% and 3.28 eV, respectively. Thin film transistors were fabricated with ZnO:Al films as active layers. The characterized device had a saturation mobility of 0.048 cm2/V-s, threshold voltage of approximately 16.1 V and a drain current on-to-off ratio (Ion/Ioff) in the order of 103.

We have achieved a drastic improvement of the performance as thin film transistor (TFT) for solution-processed IGZO thin film by controlling drying temperature of solvents containing the precursor solution. The IGZO-precursor solution was prepared by mixing of metal nitrates and two kinds of organic solvents, 2-methoxyethanol (2ME) and 2,2,2-trifluoroethanol (TFE). 2ME was used for dissolving metal nitrates. TFE was added as a solvent for reducing surface tension as small as possible, leading to improvement of the wettability of the precursor solution on the surface of the substrate. In order to discuss the relationship between morphology and drying process, the spin-coated IGZO-precursor films were dried at room temperature and 140 °C on a hotplate, respectively. Annealing of the both films was carried out at 300 °C in an electric oven for 60 min after each drying process. Drying at room temperature provides a discontinuous film, resulting in a large variation of the TFT performance. On the other hand, drying at 140 °C provides a continuous film, resulting in the higher TFT performance and a minor variation. The difference in surface morphologies would be derived from the evaporation rate of the organic solvents. The rapid evaporation at 140 °C brings about rapid pinning of the spin-coated precursor layer on the substrate. Preparation process via the drying at 140 °C gave ∼ 1 cm2 V-1 s-1 of the saturated mobility, quite small hysteresis, and 107∼ 108 of the on-off ratio.

Carbon dioxide is the major greenhouse gas that is a bi-product of industrial approaches to energy production. Forests and nonagricultural lands act as a natural sink for CO2 removal from the atmosphere; however, the amount of emitted CO2 is significantly larger than the capacity of these natural sinks. This is particularly problematic as two cornerstones of our modern world, electricity generation and transportation, hold the largest share in greenhouse gas (such as CO2) emission. This leads to malignant impacts on the natural environment and human life, such as global warming. The obvious approach to reduce the amount of generated CO2 is to limit the use of fossil fuels. However, coal-fired power plants remain the largest source of electricity generation in 2014 and an equally potent and financially reasonable source is yet to be fully developed. Hence, new systems and strategies are crucial for the remediation of CO2. In this work, we present novel TiO2 nanoparticles, synthesized via a facile solution-phase method, which show a significant visible light absorption. The synthesized nanoparticles can be applied towards photoreduction of CO2 for hydrocarbon solar fuels production. A thorough photoemission spectroscopy analysis outlined the energy structure of the materials which uncovered a sub-bandgap absorption in the visible range due to the presence of intragap states. The origins of intragap states were investigated in greater detail using various characterization techniques. An in-depth chemical composition study of the developed material using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicated that the synthesized material is considerably un-doped. Further structural analysis using transmission electron microscopy (TEM) showed that distances between visible lattice fringes are matched with ordered crystalline phases of TiO2. The core emission study using XPS revealed that the oxygen vacancy defects in the structure--i.e. likely due the synthesis--are responsible for intragap states formation. Charge dynamics were investigated using Electron Paramagnetic Resonance (EPR) spectroscopy. EPR spectra were dominated by signals from oxygen-centered surface hole trapping sites with principle g values [2.003, 2.010, 2.023]--i.e. Ti4+ ˗ O2 - on anatase. A faint signal was also observed as a function of visible light illumination at 5 K with principle g value of 1.975 that is suggestive of Ti3+ in rutile, a typical product of UV light exposure. In general, this study demonstrates the potential of a relatively inexpensive material for photoreduction of CO2 and generation of solar fuels.

Crosslinked poly[ethylene-co-(vinyl acetate)] (cPEVA) has been recently introduced as a polymer material, which can be functionalized with various shape-memory effects by solely altering the thermomechanical treatment called programming.

In this study two series of cPEVAs with different vinyl acetate contents of 18 wt% (cPEVA18) and 28 wt% (cPEVA28) comprising different crosslink densities were investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) in the temperature range of -130 °C to 120 °C. DMTA tests were performed in torsion mode, because such movements are highly relevant in the context of complex shape changes in shape-memory polymer based devices. Finally, the obtained DMTA results were compared with DMTA conducted in tension mode. Swelling experiments revealed a gel content in the range from 81% to 90% for cPEVA18 samples while for cPEVA28s a complete conversion was observed. The degree of swelling was found to decrease substantially with increasing crosslink density for both cPEVA series.

The influence of VA content and extent of crosslinking on the appearance of the respective melting (T m) and glass transition (T g) as well as the thermomechanical properties of cPEVA systems could be demonstrated by discussing both DSC and DMTA results. The temperature range of mechanical stability correlates with the VA content and is determined by decreasing T m values. The cross links do barely alter the stiffness of a PEVA up to the T m rang, but lead to constant mechanical rigidity in the rubbery range above T m.

The behavior of the redox-based resistive switching memories is influenced by chemical interactions between the electrode and the solid electrolyte, as well as by local environment. The existence of different chemical potential gradients is resulting in nanobattery effect lowering the stability of the devices. In order to minimize these effects we introduce a graphene layer at the active electrode – solid electrolyte interface. We observe that graphene is acting as an effective diffusion barrier in the SiO2-based electrochemical metallization cells and acts catalytically on the electrochemical processes prior to resistive switching.

Two important goals of the International Materials Institute for New Functionality in Glass (IMI-NFG) have been: (a) to facilitate international collaboration in glass research and, (b) to support the training of a professional workforce [1]. The REU program has been an important component of its mission since 2005. Glass science provides the central theme of our program, which has both an international and domestic component. In this paper we provide a summary of our accomplishments and experiences with this innovative, materials focused, multidisciplinary REU program. While glass provides the unifying theme of our program, the research topics and project advisers come from various departments, including not only materials science and engineering, but also biology, physics, environmental and civil engineering, electrical engineering, etc. This mode of REU operation has provided an effective means to introduce faculty from other departments to new, interdisciplinary applications of glass as an enabling material for their own work.

For the domestic REU, we partner with the Physics REU Program at Lehigh, sharing many crucial administrative aspects including housing, seminars and social events. The complementary approach of the two REU programs has been very beneficial to both of them. We summarize approaches to recruitment, selection and creating an environment conducive to cohesive and motivated community of young researchers. While the majority of student experiences have been through individual projects, we have also experimented with small teams headed by a single adviser. Because the teams can exploit the combined strengths of its members, they can accommodate a greater diversity of individual student skills and experiences. Such projects tend to provide opportunity for open-ended exploration within the context of a general goal. Some of the projects are specifically focused on developing low-cost, hands-on demonstrations for teaching glass science to others through a more experiential and intuitive approach. All of these REU projects have been incorporated in an on-line collection of activities for the science education community at large, as reported previously [2,3].

For the international component of REU, we have supported glass faculty in the country, who wish to engage their undergraduate students in a glass based summer research in the lab of an international colleague. These experiences require considerable preparation and individual attention. Here we discuss the challenges and successful strategies to deal with both the international and domestic programs.

We developed a tunnel-current based identification method by using nano-gap integrated devices. We performed electrical measurements for mono-nucleotide and oligo-nucleotide during its translocation of molecules between the nano-gap. Based on this determined electrical conductivity for single-nucleotides, we electrically identify the base-type in oligonucleotides, and found that this time-profiles represents the molecular translocation behaviors inside nano-gap. This method could be a promising for an electrical nucleotide sequencing methodology with label-free, high-speed, and low-cost.

Synthetic nanoparticles have made significant impact across a broad range of technological applications including optical nanoantennas, ultra-sensitive imaging and sensing, and diagnostics and therapeutics. Natural nanoparticles such as viruses and pollutants are major concerns for human health. High-throughput characterization of nanoparticles in terms of their size and shape is crucial for practical applications of synthetic nanoparticles and highly sensitive pathogen identification. Recently, we have demonstrated Interferometric Reflectance Imaging Sensor (IRIS) with the ability to detect single nanoscale particles [1,2].

In single-particle modality of IRIS (SP-IRIS), the interference of light reflected from the sensor surface is modified by the presence of particles producing a distinct signal that reveals the size of the particle. In our approach, the dielectric layered structure acts as an optical antenna optimizing the elastic scattering characteristics of nanoparticles for sensitive detection and analysis. We have demonstrated identification of virus articles in complex samples for various viruses in multiplexed format. Size discrimination of the imaged nanoparticles (virions) allows differentiation between modified viruses having different genome lengths and facilitates a reduction in the counting of non-specifically bound particles to achieve a limit-of-detection (LOD) of 5x103 pfu/mL for the Ebola and Marburg VSV pseudotypes. We have demonstrated the simultaneous detection of multiple viruses in serum or whole blood as well as in samples contaminated with high levels of bacteria [3]. Single nanoparticle detection with IRIS has shown promising results for protein [4] and DNA arrays with attomolar detection sensitivity.