Only show open access (1)
Over 3 years (11)
Physics and Astronomy (10)
MRS Online Proceedings Library Archive (7)
High Power Laser Science and Engineering (1)
International Journal of Astrobiology (1)
Proceedings of the International Astronomical Union (1)
BSAS (1)
International Astronomical Union (1)
Experimental platform for the investigation of magnetized-reverse-shock dynamics in the context of POLAR
On the Cover of HPL
HPL Laboratory Astrophysics
B. Albertazzi, E. Falize, A. Pelka, F. Brack, F. Kroll, R. Yurchak, E. Brambrink, P. Mabey, N. Ozaki, S. Pikuz, L. Van Box Som, J. M. Bonnet-Bidaud, J. E. Cross, E. Filippov, G. Gregori, R. Kodama, M. Mouchet, T. Morita, Y. Sakawa, R. P. Drake, C. C. Kuranz, M. J.-E. Manuel, C. Li, P. Tzeferacos, D. Lamb, U. Schramm, M. Koenig
Journal: High Power Laser Science and Engineering / Volume 6 / 2018
Published online by Cambridge University Press: 16 July 2018, e43
Print publication: 2018
The influence of a strong external magnetic field on the collimation of a high Mach number plasma flow and its collision with a solid obstacle is investigated experimentally and numerically. The laser irradiation ( $I\sim 2\times 10^{14}~\text{W}\cdot \text{cm}^{-2}$ ) of a multilayer target generates a shock wave that produces a rear side plasma expanding flow. Immersed in a homogeneous 10 T external magnetic field, this plasma flow propagates in vacuum and impacts an obstacle located a few mm from the main target. A reverse shock is then formed with typical velocities of the order of 15–20 $\pm$ 5 km/s. The experimental results are compared with 2D radiative magnetohydrodynamic simulations using the FLASH code. This platform allows investigating the dynamics of reverse shock, mimicking the processes occurring in a cataclysmic variable of polar type.
The AMINO experiment: a laboratory for astrochemistry and astrobiology on the EXPOSE-R facility of the International Space Station
H. Cottin, K. Saiagh, Y.Y. Guan, M. Cloix, D. Khalaf, F. Macari, M. Jérome, J.-M. Polienor, Y. Bénilan, P. Coll, N. Fray, M.-C. Gazeau, F. Raulin, F. Stalport, N. Carrasco, C. Szopa, M. Bertrand, A. Chabin, F. Westall, J. Vergne, L.A. Da Silva, M.-C. Maurel, D. Chaput, R. Demets, A. Brack
Journal: International Journal of Astrobiology / Volume 14 / Issue 1 / January 2015
Published online by Cambridge University Press: 03 November 2014, pp. 67-77
Print publication: January 2015
The study of the evolution of organic matter subjected to space conditions, and more specifically to Solar photons in the vacuum ultraviolet range (120–200 nm) has been undertaken in low-Earth orbit since the 1990s, and implemented on various space platforms. This paper describes a photochemistry experiment called AMINO, conducted during 22 months between 2009 and 2011 on the EXPOSE-R ESA facility, outside the International Space Station. Samples with relevance to astrobiology (connected to comets, carbonaceous meteorites and micrometeorites, the atmosphere of Titan and RNA world hypothesis) have been selected and exposed to space environment. They have been analysed after return to the Earth. This paper is not discussing the results of the experiment, but rather gives a general overview of the project, the details of the hardware used, its configuration and recent developments to enable long-duration exposure of gaseous samples in tight closed cells enabling for the first time to derive quantitative results from gaseous phase samples exposed in space.
Characteristics of biter and victim piglets apparent before a tail-biting outbreak
J. J. Zonderland, F. Schepers, M. B. M. Bracke, L. A. den Hartog, B. Kemp, H. A. M. Spoolder
Journal: animal / Volume 5 / Issue 5 / 04 April 2011
Published online by Cambridge University Press: 01 December 2010, pp. 767-775
Print publication: 04 April 2011
Little is known about the characteristics of biters and victims before the appearance of a tail-biting outbreak in groups of pigs. This study aimed to characterise biters and victims (according to gender and performance) and to quantify their behavioural development during the 6 days preceding the tail-biting outbreak. The hypotheses tested were: (a) biters are more often female, are the lighter pigs in the group, are more restless and perform more aggressive behaviour; and (b) victims are more often male, heavier and less active. Using video recordings we carried out a detailed study of 14 pens with a tail-biting outbreak among the weaned piglets. All piglets were individually marked and we observed the behaviour of biters, victims and control piglets (piglet types). In every pen, each piglet type was observed every other day from 6 days before (D−6) to the day of the first visible tail damage (i.e. day of tail biting outbreak; D0). While the number of male biters (6 of the 14 biters) and male victims (11 of the 14 victims) was not significantly different (P = 0.13), this numerical contrast was considerable. The start weight of victims was significantly (P = 0.03) higher (8.6 kg) than those of biters (7.5 kg) and control piglets (8.0 kg). Biters tended (P = 0.08) to spend longer sitting/kneeling (3.1 min/h) than controls (1.7 min/h), but no differences were seen in the time spent lying or standing. Victims tended (P = 0.07) to change posture more often (restlessness) than controls and chased penmates more (P = 0.04) than biters. Victims also performed more (P = 0.04) aggressive behaviour than biters and controls. In contrast, biters tended (P = 0.08) to be chased by penmates more often and tended (P = 0.06) to receive more aggressive behaviour than controls. Furthermore, biters spent longer manipulating the enrichment device (P = 0.01) and the posterior/tail (P = 0.02) of their penmates than controls and tended (P = 0.06) to perform more tail bites than victims. Victims received more posterior/tail manipulation (P = 0.02) and tail bites (P = 0.04) than controls. It was also noticed that, independent of piglet type, restlessness (P = 0.03) increased and the frequency of performed tail bites tended (P = 0.08) to increase in the 6 days preceding a tail-biting outbreak. These findings may contribute to the early identification of biters or victims and support the development of strategies to minimise the occurrence of tail biting.
Astrochemistry on the EXPOSE/ISS and BIOPAN/Foton experiments
H. Cottin, Y. Y. Guan, P. Coll, D. Coscia, N. Fray, F. Macari, F. Stalport, F. Raulin, C. Szopa, D. Chaput, M. Viso, M. Bertrand, A. Chabin, F. Westall, A. Brack
Journal: Proceedings of the International Astronomical Union / Volume 5 / Issue H15 / November 2009
We describe three space experiments designed to expose to space conditions, and more specifically to solar UV radiation, selected samples of organic and mineral material.
The Role of Oxygen in Low-potential Li Insertion in Metal Oxide Anode Materials
F. Leroux, L. F. Nazar
Journal: MRS Online Proceedings Library Archive / Volume 575 / 1999
Published online by Cambridge University Press: 10 February 2011, 173
Transition metal oxides are high-capacity lithium storage materials of interest as possible anode materials in the next generation of Li ion batteries. By using X-ray absorption spectroscopy we have obtained an understanding of the process of Li uptake and removal within Na0.25MoO3. Our results show the Li2O matrix on reduction is not inert; Mo-O bonds are reversibly consumed on discharge and are regenerated on charge, with the Li2O matrix acting as the oxygen reservoir. The migration of oxygen atoms from the matrix to the active centers occurs at a voltage below that expected for the Li2O free energy of formation. Polarization on charge is not due only to oxygen migration but also to metal rearrangement within the electrode material. The reversibility of the Mo-O bond formation on repeated cycles is a function of the depth of discharge, with 200 mV being the lower limit.
Enhanced Ion mobility in Aluminosilicate/Polysiloxane Network Polyelectrolytes
David P. Siska, Duward F. Shriver
A new series of polysiloxane-based single-ion conductors was prepared. These contain solvating oligoether sidechains and covalently linked aluminosilicate or alkoxy/siloxy-aluminate anions attached to the polysiloxane backbone. Of these two systems, the polymers containing aluminosilicate [(SiO)4Al]− anions show higher room temperature conductivities (10−6 S/cm) than those with alkoxy/siloxyaluminate [(SiO)2(CH2O)2A1]− anions (10−7 S/cm). The incorporation of longer covalent tethers between the alkoxy/siloxyaluminate anion and the polymer backbone results in enhanced room temperature conductivities at high ion loadings. Differential scanning calorimetry data provide a rationale for the high conductivity.
Characterization and Fuel Cell Testing of Radiation-Grafted Psi Membranes
H.-P. Brack, M. M. Koebel, A. Tsukada, J. Huslage, F. Buechi, F. Geiger, M Rota, G. G. Scherer
We have demonstrated earlier the useful performance of our PSI radiation-grafted membranes in terms of the current-voltage characteristics of 30 cm2 active area fuel cells containing these membranes and their long-term testing over 6,000 h at 60 °C. We report here on testing of PSI radiation-grafted membranes in these fuel cells at 80 °C and in short stacks comprised of two or four 100 cm2 active area cells. The in-situ degradation of membranes has been investigated by characterizing membranes both before testing in fuel cells and post-mortem after testing in fuel cells. Characterization was accomplished by means of ion-exchange capacity and infrared and Raman spectroscopic measurements. In addition, a rapid screening method for our ex-situ testing of the oxidative stability of proton-conducting membranes was developed in this work. Comparison of the initial screening test results concerning the oxidative stability of some perfluorinated, partially-fluorinated, and non-fluorinated membranes compare well qualitatively with the relative stability of these same membranes during their long-term testing in fuel cells.
A Study on Oxidized Glassy Carbon sheets for Bipolar Supercapacitor Electrodes
A. Braun, M. Bärtsch, F. Geiger, B. Schnyder, R. Kötz, O. Haas, M. Carlen, T. Christen, C. Ohler, P. Unterinahrer, E. Krause
Electrochemical Double Layer Capacitors (EDLC) for high energy and power density applications, based on glassy carbon (GO) electrodes, are being developed in our laboratory. In the context of this project, GC sheets were oxidized and investigated with Small Angle X-ray Scattering (SAXS), Electrochemical Impedance Spectroscopy (EIS) and Nitrogen Gas Adsorption (BET). During oxidation an active film with open pores is built on the surface of the GC. Upon oxidation, the internal volumetric surface area of the active film decreases, whereas the volumetric electrochemical double layer capacitance increases. We show that this effect is correlated with the opening, the growth and the coalescence of the pores.
Modelling Study on the Electrical Behaviour of YSZ-BASED Composites
G. Dotelli, F. Casartelli, I. Natali Sora, C. Schmid, C. M. Mari
Electrical properties of yttria-stabilised zirconia/alumina (YSZ/AI2O3) composites were tentatively foreseen by simulating their complex impedance spectra. A digital image-based model was developed to describe the electrical conduction process in polycrystalline mono- or multi-phase materials. The microstructure of each polycrystalline sample was reconstructed using the Voronoi tessellation technique (in fact, ad hoc modifications with respect to the original algorithm were introduced) and it was then converted into a threedimensional electrical network according to a set of well-defined rules. The network was solved via an iterative procedure for different frequency values and successively the Nyquist plot generated The complex impedance spectra of different composites were simulated considering the alumina content (5,10 and 15 %wt) as a parameter; both the bulk and grain boundary electrical conductivity were calculated and the Arrhenius plots obtained. Experimental and simulated results were compared and discussed.
Synthesis and Electrochemical characterization of LiNi1-yCoyO2 powders obtained by complex sol-gel process
F. Croce, A. D'Epifanio, A. Deptula, W. Lada, A. Ciancia, A. Di Bartolomeo, A. Brignocchi
Published online by Cambridge University Press: 10 February 2011, 97
The layered oxides, among the wide family of intercalation compounds, have received considerable attention as positive electrode materials in high-energy density lithium and lithium ion batteries. Within this frame LiNiO2 and LiCoO2 oxides and their solid solutions have been extensively studied as they (and the LiMn2O4 spinels) are the only known materials able to intercalate reversibly lithium at high cell voltage (3.5-4 V). Recently, solid solutions such as LiNi1-xCoxO2 have attracted the attention as alternative cathodes to the state of art LiCoO2 in commercial rechargeable Li-ion batteries. Here we have used the Complex Sol-Gel Process (CSGP) to prepare LiNi1-xCoxO2 (x= 0, 0.25, 0.5, 0.75, 1). Starting sols were prepared from Li+-(1-x)Ni2+-xCo2+ acetate aqueous solution in two different routes. According to route-A aqueous ammonia was added to a starting solution containing 0.2M ascorbic acid (ASC) on 1 M total Me. According to route B the starting acetate solutions were first alkalized by ammonia and then the ascorbic acid was added. Regular sols were concentrated to 1/3 of their initial volume and dried slowly up to 170°C. Thermal transformation of the gels to solids was studied by XRD and IR. The electrochemical properties of the compound LiNi0.75Co0.25O2 prepared by the Route-A were evaluated and reported.
Porous Thin-Film Anode Materials for Solid-Oxide fuel Cells
Jeffrey D. Morse, Robert T. Graff, Jeffrey P. Hayes, Alan F. Jankowski
Thin film, solid-oxide fuel cells (TFSOFCs) synthesized from an electrolyte and conductive material are developed using photolithographic patterning and physical vapor deposition. The anode layer must enable combination of the reactive gases, be conductive to pass the electric current, and provide mechanical support to the electrolyte and cathode layers. The microstructure and morphology desired for the anode layer should facilitate generation of maximum current density from the fuel cell. For these purposes, the parameters of the deposition process and post-deposition patterning are developed to optimize a continuous porosity across the anode layer. The anode microstructure is characterized using scanning electron microscopy and the power ouput generated through current-voltage measurement.