Microstructure and multifunctional properties of liquid + polymer bicomponent structural electrolytes: Epoxy gels and porous monoliths

Multifunctional structural batteries and supercapacitors have the potential to improve performance and efficiency in advanced lightweight systems. A critical requirement is a structural electrolyte with superior multifunctional performance. We present here structural electrolytes prepared by the integration of liquid electrolytes with structural epoxy networks. Two distinct approaches were investigated: direct blending of an epoxy resin with a poly(ethylene‐glycol) (PEG)‐ or propylene carbonate (PC)‐based liquid electrolyte followed by in‐situ cure of the resin; and formation of a porous neat epoxy sample followed by backfill with a PC‐based electrolyte. The results show that in situ cure of the electrolytes within the epoxy network does not lead to good multifunctional performance due to a combination of plasticization of the structural network and limited percolation of the liquid network. In contrast, addition of a liquid electrolyte to a porous monolith results in both good stiffness and high ionic conductivity that approach multifunctional goals. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42681.     

Applications of analytical electron microscopy to guide the design of boron carbide

Compositional analysis of boron carbide on nanometer length scales to examine or interpret atomic mechanisms, for example, solid-state amorphization or grain-boundary segregation, is challenging. This work reviews advancements in high-resolution microanalysis to characterize multiple generations of boron carbide. First, ζ-factor microanalysis will be introduced as a powerful (scanning) transmission electron microscopy ((S)TEM) analytical framework to accurately characterize boron carbide. Three case studies involving the application of ζ-factor microanalysis will then be presented: (1) accurate stoichiometry determination of B-doped boron carbide using ζ-factor microanalysis and electron energy loss spectroscopy, (2) normalized quantification of silicon grain-boundary segregation in Si-doped boron carbide, and (3) calibration of a scanning electron microscope X-ray energy-dispersive spectroscopy (XEDS) system to measure compositional homogeneity differences of B/Si-doped arc-melted boron carbides in the as-melted and annealed conditions. Overall, the improvement and application of advanced analytical tools have helped better understand processing–microstructure–property relationships and successfully manufacture high-performance ceramics.     

Nucleation mechanism for the direct graphite-to-diamond phase transition

Graphite and diamond have comparable free energies, yet forming diamond from graphite in the absence of a catalyst requires pressures that are significantly higher than those at equilibrium coexistence. At lower temperatures, the formation of the metastable hexagonal polymorph of diamond is favoured instead of the more stable cubic diamond. These phenomena cannot be explained by the concerted mechanism suggested in previous theoretical studies. Using an ab initio quality neural-network potential, we carried out a large-scale study of the graphite-to-diamond transition assuming that it occurs through nucleation. The nucleation mechanism accounts for the observed phenomenology and reveals its microscopic origins. We demonstrate that the large lattice distortions that accompany the formation of diamond nuclei inhibit the phase transition at low pressure, and direct it towards the hexagonal diamond phase at higher pressure. The proposed nucleation mechanism should improve our understanding of structural transformations in a wide range of carbon-based materials.     

Fettalkoholethoxylate mit eingeengter Homologenverteilung - Entwicklung neuer Alkoxylierungskatalysatoren

Fatty Alcohol Ethoxylates with Narrow Range Homologue-Distribution - Development of New Catalysts for Alkoxylation Fatty alcohol ethoxylates are most important within the group of nonionic surfactants. They are manufactured by acid or basic catalyzed reaction of fatty alcohols with ethylenoxide. The product composition, particularly the homologue distribution, depends on the nature of catalyst. Basic catalysts, which are widely used in technical processes, yield products with a broad range homologue distribution. Three new catalysts for alkoxylation are presented, which yield fatty alcohol ethoxylates with narrow-range homologue distribution. These narrow-range ethoxylates exhibit new interesting properties.     

Monitored steady-state excitation and recovery (MSSER) radiation force imaging using viscoelastic models

Acoustic radiation force imaging methods distinguish tissue structure and composition by monitoring tissue responses to applied radiation force excitations. Although these responses are a complex, multidimensional function of the geometric and viscoelastic nature of tissue, simplified discrete biomechanical models offer meaningful insight to the physical phenomena that govern induced tissue motion. Applying Voigt and standard linear viscoelastic tissue models, we present a new radiation force technique - monitored steady-state excitation and recovery (MSSER) imaging - that tracks both steady-state displacement during prolonged force application and transient response following force cessation to estimate tissue mechanical properties such as elasticity and viscosity. In concert with shear wave elasticity imaging (SWEI) estimates for Young's modulus, MSSER methods are useful for estimating tissue mechanical properties independent of the applied force magnitude. We test our methods in gelatin phantoms and excised pig muscle, with confirmation through mechanical property measurement. Our results measured 10.6 kPa, 14.7 kPa, and 17.1 kPa (gelatin) and 122.4 kPa (pig muscle) with less than 10% error. This work demonstrates the feasibility of MSSER imaging and merits further efforts to incorporate relevant mechanical tissue models into the development of novel radiation force imaging techniques.     

New solvent for polyamides and its application to the electrospinning of polyamides 11 and 12

Polyamides with long hydrocarbon chains, e.g. PA11 and PA12, are generally dissolved in phenolic or fluoric solvents that prevent these polymers from being electrospun and used in many applications because of their high boiling point and/or prohibitive cost. We demonstrate that a mixture of formic acid and dichloromethane can lead to the dissolution of various polyamides enabling their subsequent electrospinning. Nanofibers and nanoribbons of 130 nm and greater in average diameter were obtained and characterized using scanning electron microscopy and Raman spectroscopy.     

Integrated operation of diagnostic and control systems

In fusion research the ability to generate and sustain high performance fusion plasmas gains more and more importance. Optimal combinations of magnetic shape, temperature and density profiles as well as the confinement time are identified as advanced regimes. Safe operation in such regimes will be crucial for the success of ITER and later fusion reactors. The operational space, on the other hand, is characterized by nonlinear dependencies between plasma parameters. Various MHD limits must be avoided in order to minimize the risk of a disruption.Sophisticated feedback control schemes help to tackle this challenge. But these in turn require detailed information on plasma state in time to allow proper reaction. Control system and diagnostic systems therefore must establish a symbiotic relationship to carry out such schemes. Today, all major fusion devices implement such a concept.An implementation of such a concept with sustained integration is presented using the example of ASDEX Upgrade. It covers data communication via a real-time network, synchronization mechanisms for data-driven algorithm execution as well as operational aspects and exception handling for failure detection and recovery. A modular distributed software framework offers standardized user algorithm interfaces, automated workflow procedures and the application of various computer and network hardware components. Designed with a special focus on reliability, robustness and flexibility, it is a sound base for exploring ITER-relevant plasma regimes and control strategies.     

Laser beam welding of low weight materials and structures

In this presentation an overview will be given about laser beam welding of aluminium. Different aspects regarding process parameters, metallurgical aspects, weld seam properties and possible applications will be discussed.     

Optical and electrochemical properties of optically transparent,boron-doped diamond thin films deposited on quartz

The optical and electrochemical properties of transparent, boron-doped diamond thin film, deposited on quartz, are discussed. The films were deposited by microwave-assisted chemical vapor deposition, for 1-2 h, using a 0.5% CH4/H2 source gas mixture at 45 Torr and 600 W of power. A high rate of diamond nucleation was achieved by mechanically scratching the quartz. This pretreatment leads to the formation of a continuous film, in a short period of time, which consists of nanometer-sized grains of diamond. The thin-film electrode was characterized by cyclic voltammetry, atomic force microscopy, and UV-visible absorption spectrophotometry. The film's electrochemical response was evaluated using Ru(NH3)6(3+/2+) in 1 M KCl, Fe(CN)6(3-/4-) in 1 M KCl, and chlorpromazine (CPZ) in 10 mM HClO4. The film exhibited a low voltammetric background current and a stable and active voltammetric response for all three redox systems. The optical transparency of the polycrystalline film in the visible region was near 50% and fairly constant between 300 and 800 nm. The optical and electrical properties were extremely stable during 48-h exposure tests in various aqueous (HNO3, NaOH) solutions and nonaqueous (e.g., chlorinated) solvents. The properties were also extremely stable during anodic and cathodic potential cycling in harsh aqueous environments. This stability is in stark contrast to what was observed for an indium-doped tin oxide thin film coated on quartz. The spectroelectrochemical response (transmission mode) for CPZ was studied in detail, using a thin-layer spectroelectrochemical cell. Thin-layer voltammetry, potential step/ absorption measurements, and detection analytical figures of merit are presented. The results demonstrate that durable, stable, and optically transparent diamond thin films, with low electrical resistivity (approximately 0.026 omega x cm) laterally through the film, can be deposited on quartz.     

The growth kinetics of the discontinuous precipitation reaction in Mg−Al alloys

The extent, the growth rate and the interlamellar spacing of the discontinuous precipitation reaction in Mg−Al solid solutions with 5, 7, 9, and 11 at. pct Al are presented and analyzed by the theories of Turnbull, Cahn and Sundquist.K ₀λD ^B-values are computed with the aid of Turnbull's formula as well as Sundquist's solution of the diffusion problem. The activation energies confirm the assumption of grain boundary diffusion to be the rate controlling process. The thermodynamic of the reaction was treated on the base of the regular solution. The “maximum growth rate” criterion yields interlamellar spacings deviating clearly from the experimental values whether Turnbull's formula or Cahn's treatment was taken as a basis. The application of Sundquist's concept provides the boundary shape as a function of interlamellar spacing. The parameter ϑ', by which the boundary shape is determined, lies in the range -0.3 ⪯ ϑ' ⪯ 2 at the experimental spacing, which is the minimum true spacing. These ϑ'-values correspond to boundary shapes with no or moderate recesses. Observed boundary shapes are not in contrast to these results. The development of recesses by increasing interlamellar spacing is observed too and confirmed theoretically. Deep recesses guarantee the creation of new lamellae which reduce the enlarged spacings to such with more stable boundary shapes. This leads to the conclusion that the concept of unique interlamellar spacing must be abandoned in favor of a distribution of spacings according to the probability of nucleation of new lamellae.