Two-photon fabrication is a powerful method of fabricating complex microstructures. Superresolution by methods analogous to stimulated emission depletion (STED) has been described previously, enabling sub-100 nm imaging with 800 nm light. STED-related methods of enhancing imaging resolution require photoresists with exposure conditions for which the photoresist exhibits negative contrast, i.e., image density decreases with increasing exposure from the depletion beam. We have observed decreasing voxel size with increasing exposure during two-photon initiated polymerization of acrylate- and methacrylate-based photoresists, that is, negative imaging contrast, γ < 0, independent of the type of photoinitiator. Negative contrast is not observed in epoxy-type photoresists containing photoacid generators. An investigation of the exposure conditions has led us to conclude that radical-radical recombination at high exposure is responsible for negative contrast. Results of the investigation, discussion of the proposed mechanism for negative contrast and implications for two-photon superresolution will be presented.

In developing photovoltaic (PV) systems with reliable lifetime performances, it is critical to have quantitative knowledge of not just initial properties and performances, but also their performance over the warrantied 25 year lifetime. In 2010, the Science for Energy Technology Workshop, convened by U.S Department of Energy (DOE) Basic Energy Science, prioritized photovoltaic module lifetime and degradation science (L&DS), which serve as the basis for quantitative and mechanistic understanding of lifetime performance. In order to better understand degradation rates and mechanisms of PV systems in the real-world environment, the SDLE SunFarm at Case Western Reserve University has been created, which is a highly instrumented outdoor test facility with 148 PV modules and > 8000 samples on sun for weathering and degradation studies of materials components and systems designed for long-lived energy systems. I-V and power performance of 10 multi-crystalline silicon PV modules from different manufacturers, using baseline and continuous power monitoring and comprehensive weather and solar resource monitoring, to enable time series analysis for insights into performance characteristics and initial degradation.

Five modules from each manufacturer were exposed using mirror augmentation in typical (Cleveland, OH) climatic conditions. The mirror augmentation used geometric concentration factors of 1X, 1.5X and 1.9X of the nominal 1 sun. The effect of mirror augmentation on the modules' performance is reported. A Daystar multi-tracer was used to measure I-V curves of individual modules every 15 minutes while power output under maximum power point tracking was monitored continuously. Monitoring environmental factors (wind speed, wind direction, rainfall, and humidity), solar resource, and module temperatures allow for determination of the effects of these conditions on module power production. Power data was corrected to standard test condition (STC) according to climatic and solar irradiance. Changes in fill factor, short circuit current, open circuit voltage and maximum power are reported for each module. With time series analysis, a better understanding of the module's performance over time and under environmental conditions can be developed.

Papers in the Appendix were published in electronic format as Volume 1534

The continues development of thermoelectric generators causes a permanent improvement of their characteristics. New types of thermoelectric generators can work at temperatures up to 1000 K. With this, special measurement equipment is needed to control the electrical parameters of the new developed specimens. The devices must be tested over the whole range of operating temperatures. For each temperature value a series of electrical measurements has to be performed. To establish the maximal output power of the thermoelectric generators, a load resistor with variable resistance has to be connected to the output of thermoelectric generator. The measurement system should measure the electrical current through the load resistor and the voltage over this resistor to determine the device parameters. A large amount of measurement data have to be collected and processed to evaluate the electrical characteristics of the specimen and to present them in graphical form, suitable for the comparison with others specimens.

In this paper, we developed a microscopic approach to understand rubber reinforcement using coarse-grained molecular dynamics simulations. We investigated static uniaxial tensile behavior of filled and unfilled rubber models, and found two reinforcement mechanisms. One of these is the same as the mechanism predicted by Guth, which depends only on the volume content of fillers. We have confirmed this mechanism at small strain region. The other is caused by filler-filler network created by the advantage of chemical bond at large strain. In this region, some polymers linked fillers and were stretched, that is, these polymers generated tension. Additionally, we investigated the effect of filler distribution on rubber reinforcement.

Over the past few years, ion implanters specifically developed for the high throughput required by the silicon photovoltaic industry, have become commercially available. Recent research and development has focused on the formation of doped surface regions, particularly the formation of selective emitters. In this study we explore two effects of ion implantation into a thermal silicon dioxide passivating/antireflection dielectric. We show evidence that the electronic and optical performance of the layer can be improved via the incorporation of charges created within the dielectric film and the creation of a graded refractive index, minimizing the surface recombination and reflection losses respectively.

We report on preliminary studies of low (14 at.%) and high (53at.%) concentration Mn doped MgO films deposited by co-sputtering from metallic Mn and Mg targets. The structural, surface morphologies and magnetic properties of the films of different thickness were studied. All the as grown films are found to be amorphous and film surfaces are found to be flawless and homogeneous. We observe at room temperature robust ferromagnetic loops with a saturation magnetization value that is a function of film thickness reaching a maximum of ∼38.5 emu/cm3 in the Mn0.53Mg0.47O film at a thickness of ∼92 nm. In thicker films room-temperature ferromagnetic ordering is suppressed and eventually at a thickness around 120nm the expected diamagnetism of the bulk appears. The origin of ferromagnetism may be attributed to cation defects at the Mg-site.

The hydrogen uptake and redistribution in Zircaloy-4 specimens applied to loss of coolant accident (LOCA) simulation experiments and in mechanical pre-loaded samples were investigated by means of ex-situ and in-situ neutron imaging. The results of these investigations were compared with results from mechanical tests. Hydrogen absorption may have a strong influence on the mechanical properties of zirconium alloys. A local enrichment of the absorbed hydrogen may result in brittle fracture at these positions in the tensile test. On the other hand, stress fields in the material affect the hydrogen uptake as well as its distribution in the material. In-situ investigations confirmed the existence of an initial oxide layer formed at room temperature by contact with air. This oxide layer suppresses the hydrogen uptake until dissolution in the zirconium matrix.

A detailed analysis of leakage current density-gate voltage measurements of gate stacks composed of PLD grown ultra thin films of LaGdO3 (LGO) on p-type silicon substrates with 8.4 Å EOT is presented. Temperature dependent leakage measurements revealed that forward bias current was dominated by Schottky emission over trap assisted tunneling below 1.2 MV/cm and quantum mechanical tunneling above this field. The physical origin of the reverse bias current was found to be a combination of Schottky emission and trap assisted tunneling. Low leakage current densities in the range from 2.3×10-3 to 29×10-3 A/cm2 were recorded for films with EOT from 1.8 to 0.8 nm, that are at least four or more orders below the ITRS specifications and its SiO2 competitors.

We observe the heat flux exchanged by the hot tip of a scanning thermal microscope, which is an instrument based on the atomic force microscope. We first vary the pressure in order to analyze the impact on the hot tip temperature. Then the distance between the tip and a cold sample is varied down to few nanometers, in order to reach the ballistic regime. We observe the cooling of the tip due to the tip-sample heat flux and compare it to the current models in the literature.

Biofilms are a major source of medical device-associated infections, due to their persistent growth and antibiotic resistance. Recent studies have shown that engineering surface nanoroughness has great potential to create antibacterial surfaces. In addition, stimulation of bacterial metabolism increases the efficacy of antibacterial agents to eradicate biofilms. In this study, we combined the antibacterial effects of nanorough topographies with metabolic stimulation (i.e., fructose metabolites) to further decrease bacterial growth on polyvinyl chloride (PVC) surfaces, without using antibiotics. We showed for the first time that the presence of fructose on nanorough PVC surfaces decreased planktonic bacteria growth and biofilm formation after 24 hours. Most importantly, a 60% decrease was observed on nanorough PVC surfaces soaked in a 10 mM fructose solution compared to conventional PVC surfaces. In this manner, this study demonstrated that bacteria growth can be significantly decreased through the combined use of fructose and nanorough surfaces and thus should be further studied for a wide range of antibacterial applications.

A Compact Planar Magnetron Plasma Sputtering Deposition Device (CPM-PSDD) has been used to deposit TiO2 on silicon, glass and cotton cloth. An 80 mm diameter Ti target was placed at the cathode and was sputtered by argon-oxygen plasma with 10-20 mA discharge current and -300 V to -450 V discharge potential. Reactive oxygen gas fed into the system at 13:1 Ar:O2 sccm ratio for the deposition durations between one to four hours. The deposited films exhibited both anatase and rutile phases. Cotton cloths were dipped in methyl blue to evaluate the photocatalytic activity of the film.

The junction formation when Cu(InGa)Se2 is deposited onto ZnO in a superstrate configuration (glass/window/buffer/Cu(InGa)Se2/contact) is investigated by x-ray photoelectron spectroscopy and analysis of device behavior. When Cu(InGa)Se2 is deposited on ZnO, a Ga2O3 layer is formed at the interface. Approaches to avoid the formation of this unfavorable interlayer are investigated. This includes modifications of the process to reduce the thermal load during deposition and improvement of the thermal stability of the ZnO buffer layer. It was demonstrated that both lowering of the substrate deposition temperature and deposition of the ZnO buffer layer at elevated temperature limits the Ga2O3 formation. The presence of Ga2O3 at the junction does affect the device behavior, resulting in a kink in JV curves measured under illumination. This behavior is absent in devices with limited Ga2O3 formation.

In order to improve the charge/discharge cycling performance of the LiMn2O4 cathode, the spinel LiMn2O4 is coated on the structurally stable SiO2 nanosphere cores, LiMn2O4@SiO2. The core-shell LiMn2O4@SiO2 nanosphere cathodes are prepared by the MnCO3 precipitation on the silica surface and the following solid state reaction of MnCO3@SiO2 with a lithium salt. The charge/discharge cycle stability has improved by the nanostructural characteristics of the LiMn2O4@ shell on the SiO2 core. The cathode composed of LiMn2O4@SiO2 nanospheres exhibits higher capacity retention of 97% than that of LiMn2O4 nanoparticles of 89%, after 100 battery cycles at a 10C rate.

Metal hydrides present a feasible means of energy storage and hydrogen sensing but have several performance criteria that must be addressed, including the hysteresis effect during hydrogen loading and unloading. We present the results of a theoretical and experimental study which demonstrates the possibility to control or eliminate hysteresis during metal-hydride transformation in epitaxial Pd thin films. Theoretical analysis predicts stabilization of two-phase metal-hydride state in film due to its elastic interaction with the substrate. It is shown, by atomic force and scanning electron microscopy, that transformation in 100nm thick epitaxial Pd films on Al2O3 substrate proceeds by the formation of transversely modulated two-phase nanostructure. Morphology and crystallographic orientation of the metal-hydride interface corresponds to the theoretically predicted characteristics of coherent phases.

Well ordered arrays of carbon nanotubes (CNTs) are of interest for a broad range of potential applications including energy storage and as catalyst supports. On some substrates such as copper and nickel, CNTs do not grow well or at all. We have previously shown that mesoporous silica thin films can be deposited onto metal substrates including copper and nickel, and that, after removal of the templating surfactant, the mesoporous silica film can be used as template for the electrodeposition of metals to give metal nanostructures.[Campbell et. al., Micro. Meso. Mater., 97, 114-121 (2006)] The size of the metal nanostructures makes them attractive as seeds for growth of CNTs. We have found that under appropriate conditions nickel deposited into mesoporous silica can act as catalyst for CNT growth on a number of different substrates including copper coated silicon wafers, and nickel foam. Using three different furnaces and different feed streams it was found that the growth is sensitive to carbon source; acetylene and ethylene both produced CNTs whereas attempts to produce CNTs using xylene have so far been unsuccessful.

Well ordered mesoporous silica thin films could potentially give arrays of nanorod seeds, leading to well ordered arrays of CNTs, SEM images of some of our samples show dense CNT arrays, but do not indicate significant ordering.

We report an increase in superconducting temperature of magnesium diboride (MgB2) by minute single-wall carbon nanotubes (SWCNT) inclusions. The SWCNTs concentration was varied from 0.1wt% to 1.0wt%. The temperature dependence resistivity of sintered MgB2- SWCNTs composites containing 0.1wt%, 0.5wt% and 1.0wt% were measured and compared with that of the pure MgB2. The superconducting critical temperature (Tc) of the MgB2 increased from 40 K to as high as 42.4 K for the MgB2 containing 0.5wt% of SWCNTs. The room temperature resistivity ratio (RRR) shows dependence on the sample composition. The temperature width (ΔT) decreases with increasing SWCNT content from 0.1wt% to 1.0wt%. The normal state resistivity data were fitted with the generalized Block-Grüneisen function obtaining a Debye temperature of ∼ 900K.

Pyrochlore type compound Nd2(Zr,Ce)2O7 is considered to precipitate in ThO2-based fuel, that is not observed in irradiated UO2. In order to evaluate the influences on fuel properties, thermomechanical properties of the pyrochlore type compounds, Ln2Zr2O7 (Ln=La, Pr, Nd, Eu, Gd, Dy) and Nd2Ce2O7 were investigated. We synthesized the samples by solid-state reaction and pelletized by spark plasma sintering to make high density (≥ 90 %T.D.) pellets. The phase states and lattice parameters were examined by using X-ray diffraction and SEM/EDX analysis. The lattice parameters of Ln2Zr2O7 depended on the ionic radii of lanthanide ions. The heat capacity, thermal conductivity, linear thermal expansion coefficient, and elastic constants were also measured. It was confirmed that the thermal conductivities for Ln2Zr2O7 were lower than that for ThO2 and depended on Ln ionic radii. The values of elastic constants tended to increase with increasing the Ln ionic radii, corresponding to the thermal conductivity.

Spectral shifts of the emission lines of Erbium ions in Lithium Niobate are used to determine the build-up of intrinsic electric fields under intense light irradiation. The observed spectral shifts can be translated into internal electric fields through a calibration using applied external fields. The studies show that a substantial field can be created locally (up to 150kV/mm) with observed occasional electric breakthroughs that have a corresponding field strength of up to 35kV/mm. In addition, a modification of some Erbium incorporation sites is observed suggesting its relationship with a defect that can by photo-ionized, such as Fe2+/Fe3+.

Dimethyl sulfoxide (DMSO) and several naturally occurring polyols or their derivatives (like glycerol) have been used as cryoprotective agents (CPAs) for many years. However DMSO shows high cytotoxicity and affects differentiation of cells, so it needs to be removed immediately after thawing, whereas polyols are comparatively weaker cryoprotective agents. Furthermore, some types of cells are extremely sensitive to damage during freezing and thawing, so cannot be cryopreserved properly using current CPAs. So there is a great need to develop newer cryoprotective agents with lower cytotoxicity and high efficiency for many biological and medical purposes.

Recently we showed that carboxylated poly-L-lysine, which is classified as a polyampholyte, has a cryoprotective effect on cells in solution without any other cryoprotectant. Polyampholytes are charged polymers with both positively and negatively charged groups.

Therefore, in this research, we are developing a completely synthetic polyampholytes by radical polymerization and will try to elucidate the key parameters of cryoprotective properties. Here we chose reversible addition fragmentation chain transfer (RAFT) polymerization as the mode of polymerization as it is a kind of living polymerization method and can give control over the molecular weight and composition of the copolymer. We evaluated the livingness of the 1:1 copolymer with methacrylic acid (MAA) and 2-Dimethylamino ethyl methacrylate (DMAEMA) with 2-(Dodecylthiocarbonothioylthio)-2-methylpropionic acid as the RAFT agent and the polymer solution showed good cell viability of L929 cells after cryopreservation at 15% copolymer concentration.