Conductivity enhancement within garnet-rich polymer composite electrolytes via the addition of succinonitrile

All-solid-state lithium-ion batteries (ASSLIBs) are promising alternatives to conventional organic electrolyte-based batteries due to their higher safety and higher energy densities. Despite advantages, ASSLIBs suffer from issues like high charge transfer resistances due to the brittleness of the inorganic solid electrolyte and chemical instabilities at the lithium/electrolyte interface. Within this work, we investigate composite electrolytes (CEs) based on garnet-type Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO), polyethylene oxide, and lithium bis(trifluoromethanesulfonyl)imide, prepared via a solvent-free cryo-milling approach in contrast to conventional solvent-mediated synthesis. Compositions ranging from polymer-rich to garnet-rich systems are investigated via X-ray diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy in order to determine the compatibility of the cryo-milling process toward membrane fabrication along with the possible chemical interactions between the composite membrane components. Electrochemical impedance spectroscopy is used to study the role of ceramic to polymer weight fraction on ionic conductivity. It is shown that the addition of succinonitrile (SCN) to the garnet-rich CEs can significantly improve the ionic conductivity compared to the SCN-free CEs.     

Phase Transformations and Grain Growth in β-stabilized TiAl Alloys

Solid-state phase transformations and grain growth of an intermetallic γ-TiAl alloy were investigated in-situ using high-temperature laser scanning confocal microscopy (HTLSCM). During isothermal annealing in the single β-phase region, significant grain coarsening was observed. On cooling beneath the β-transus temperature with different rates, a CCT diagram was evaluated for the initiation of β to α phase transformation and changes in the morphology were observed.     

Suppression of inward-rectifying K+ channels KAT1 and AKT2 by dominant negative point mutations in the KAT1 alpha-subunit

Na(+)-glucose transport and transepithelial permeability were investigated during symptomatic acute cryptosporidiosis in newborn rats. The infection resulted in a significant (P < 0.01) decrease in the ileal short-circuit current and a nonsignificant fall in the transepithelial potential difference and conductance. In glucose-stimulated conditions, the rise in ileal short-circuit current and transepithelial permeability were significantly lower in Cryptosporidium parvum-infected rats than in controls (delta Isc = 3.24 +/- 1.21 microA.cm-2 vs delta Isc = 5.09 +/- 2.23 microA.cm-2 in infected and control animals, respectively; P < 0.001; delta PD = -0.35 +/- 0.13 mV vs delta PD = -0.44 +/- 0.14 mV for infected and control animals, respectively; P < 0.01). Electrical parameters were not affected by addition of the cyclooxygenase inhibitor indomethacin in either Cryptosporidium-infected newborn rats or controls. Horseradish peroxidase and mannitol flux studies demonstrated a significant decrease (P < 0.05) in transepithelial molecular permeability in infected enterocyte rats, HRP flux = 380, range 68-5570 ng.cm-2, and mannitol flux = 1.06, range, 0.34-1.44%.cm-2.min-1, compared with controls rats, HRP flux = 4446 range, 1121-124,363 ng.cm-2, and mannitol flux = 1.99, range, 0.57-5.09%.cm-2.min-1; P < 0.05. These effects could originate from C. parvum-induced alteration of intracellular trafficking of pinocytosis vesicles and therefore account for the decrease in permeability to solute and macromolecules, together with impaired transcellular nutrient transport, in suckling rats.     

Behavior of tissue-engineered human cartilage after transplantation into nude mice

Cartilage lacks the ability to regenerate structural defects. Therefore, autologous grafting has been used routinely to replace cartilaginous lesions. Because tissue engineering of human cartilage with the help of bioresorbable polymer scaffolds is possible in experimental models, the demand for the clinical application grows. In this study we present an analysis of the behavior of transplants made of human chondrocyte pools, agarose and the resorbable polymer scaffold Ethisorb and a preliminary comparison with transplants made of single patients' cells and Ethisorb but without the additional ingredient agarose. Chondrocytes were isolated from the matrix of human septal cartilage by enzymatic digestion. The pool cells were kept in monolayer culture for 2 weeks, the single patients' cells for 3–4 weeks. Chondrocyte pools were suspended in agarose and seeded into the resorbable polymer scaffold Ethisorb. Single patients' cells were seeded without agarose. All cell–polymer constructs were kept in perfusion culture for 10–14 days and transplanted subcutaneously into thymusaplastic nude mice. Additionally we implanted Ethisorb fleeces embedded in agarose without chondrocytes. After 6, 12 and 24 weeks the animals were sacrificed and the specimens were explanted and analyzed histochemically and immunohistochemically. Polymer scaffolds not seeded with chondrocytes did not show cartilage formation. Resorption was complete after 12 weeks in vivo. Transplants from cell pools remained mechanically stable over 24 weeks apart from four transplants that were resorbed completely. Cartilage formation was observed in all pool-specimens with the presence of chondronic structures and a homogeneous matrix containing hyaline cartilage-specific matrix molecules such as collagen type II. Single patients' transplants showed hyaline cartilage matrix synthesis and mechanical stability as well. Chondrocyte pools are a suitable method to study cartilage engineering of human cells in vitro and in vivo in experimental models. Under clinical conditions it is, however, necessary to study the generation of cartilage from single patients' cells. We showed that it is possible without additional ingredients such as agarose. However, variations in the preliminary results show that the clinical application with human cells is more difficult than one would expect when using human chondrocyte pools. Further studies need to be performed to find out which individual factors influence the in vitro engineered cartilage's fate in vivo. © 1999 Kluwer Academic Publishers     

Transalkylation of biphenyl over zeolites: Optimizing the reaction conditions and kinetic modeling

The shape-selective transalkylation of biphenyl with pentamethylbenzene over ultrastable Y-faujasites to produce para-methylated biphenyls was studied in the liquid slurry phase. The reaction was carried out in a discontinuously operated stainless steel autoclave using n-heptane as the solvent with a temperature range of 513 to 533 K and a pressure of 3 MPa. As for the progress of the reaction the presence of strong Brønsted acid sites was essential, an ultrastable faujasite treated with aqueous hydrochloric acid having a high content of those sites was used as the catalyst. Thus, a yield of the target product 4,4′-dimethylbiphenyl of above 11% referring to biphenyl could be achieved. The effect of the operating conditions on the formation of the target product was investigated. The decisive influence was acted out by the molar ratio of biphenyl to alkylating agent, in so far as a surplus of pentamethylbenzene of 7:1 referring to biphenyl enhanced the yield of the target product to 14%. The kinetics of the reaction could be successfully descibed with a lumped reaction scheme, introducing pseudo components, summarizing structural isomers, and pseudo reactions, such as the formation of coke.     

The JUSTSAP experiment on STS-95

An instrumented flow cell in the form of a cylinder with differentially heated end walls and adiabatic sidewalls was flown on STS-95 as the Japan-US Thermal Science Accelerometer Project (JUSTSAP). The purpose of the experiment was to map disturbances in the thermal field during the course of a Shuttle mission in order to correlated them with various mission events and to determine if any global transport could be detected from second order, non-zero time average flows resulting from periodic accelerations (g-jitter). Significant disturbances in the thermal field were noted each time the Shuttle changed attitude, such as the maneuver to -Z solar inertial, which is done periodically for thermal conditioning. Burns from the main thrusters associated with the launch and retrieval of the Spartan satellite produced overturning flows, as might be expected. During extended periods in which the attitude was held constant, the perturbations to the thermal field correlate extremely well with calculated accelerations from gravity gradient and drag. Fair agreement was found between the observed temperature perturbations and those predicted from a modification of the analytical model developed by Bejan and Tien (B&T) for the flow and heat transfer in an infinite cylinder with a constant axial thermal gradient. A full three-dimensional computational fluid dynamic analysis with more realistic thermal boundary conditions provided better agreement after adjustments were made to account for the heat flow away from the measuring thermistors. Once calibrated with a reliable thermal model, the flow cell was found to serve as a high-precision accelerometer, capable of measuring the quasi-steady acceleration with a sensitivity of better than 0.1 micro-g in the presence of the higher amplitude g-jitter typical of Shuttle operations. Further, it was found that the gravity gradient acceleration accounted for virtually all of the observed quasi-steady accelerations during such extended periods. The thermal response time of the JUSTSAP was too slow to expect to see the effects of fluctuating first order flows resulting from the vibrational environment of the Shuttle. However, an indication of a change in the thermal field near the ends of the flow cell was seen during periods of crew exercise that may possibly be attributed to circulating eddies resulting from the higher order terms in the momentum equation. At higher amplitudes, these second order effects can produce non-zero time average flows of a global nature, as can the start-up transients in first-order periodic flows. No such effects were observed, thus it is possible to place an upper limit on the integrated power spectral density of the vibrational environment experienced as well as the nature of the start-up transients of the periodic flows.     

Ultra-fast vapour-liquid-solid synthesis of Si nanowires using ion-beam implanted gallium as catalyst

The feasibility of gallium as a catalyst for vapour-liquid-solid (VLS) nanowire (NW) growth deriving from an implantation process in silicon by a focused ion beam (FIB) is investigated. Si(100) substrates are subjected to FIB implantation of gallium ions with various ion fluence rates. NW growth is performed in a hot wall chemical vapour deposition (CVD) reactor at temperatures between 400 and 500?°C with 2% SiH(4)/He as precursor gas. This process results in ultra-fast growth of (112)- and (110)-oriented Si-NWs with a length of several tens of micrometres. Further investigation by transmission electron microscopy indicates the presence of a NW core-shell structure: while the NW core yields crystalline structuring, the shell consists entirely of amorphous material.     

Isogeometric finite element data structures based on Bézier extraction of T‐splines

We develop finite element data structures for T‐splines based on Bézier extraction generalizing our previous work for NURBS. As in traditional finite element analysis, the extracted Bézier elements are defined in terms of a fixed set of polynomial basis functions, the so‐called Bernstein basis. The Bézier elements may be processed in the same way as in a standard finite element computer program, utilizing exactly the same data processing arrays. In fact, only the shape function subroutine needs to be modified while all other aspects of a finite element program remain the same. A byproduct of the extraction process is the element extraction operator. This operator localizes the topological and global smoothness information to the element level, and represents a canonical treatment of T‐junctions, referred to as ‘hanging nodes’ in finite element analysis and a fundamental feature of T‐splines. A detailed example is presented to illustrate the ideas. Copyright © 2011 John Wiley & Sons, Ltd.     

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