K\"ahler groups, real hyperbolic spaces and the Cremona group

Generalizing a classical theorem of Carlson and Toledo, we prove that any Zariski dense isometric action of a K\"{a}hler group on the real hyperbolic space of dimension at least 3 factors through a homomorphism onto a cocompact discrete subgroup of PSL(2,R). We also study actions of K\"{a}hler groups on infinite dimensional real hyperbolic spaces, describe some exotic actions of PSL(2,R) on these spaces, and give an application to the study of the Cremona group.Comment: Referee's comments and minor corrections included. With an appendix by Serge Canta

A shape-deformable and thermally stable solid-state electrolyte based on a plastic crystal composite polymer electrolyte for flexible/safer lithium-ion batteries

A solid-state electrolyte with reliable electrochemical performance, mechanical robustness and safety features is strongly pursued to facilitate the progress of flexible batteries. Here, we demonstrate a shape-deformable and thermally stable plastic crystal composite polymer electrolyte (denoted as "PC-CPE") as a new class of solid-state electrolyte to achieve this challenging goal. The PC-CPE is composed of UV (ultraviolet)-cured ethoxylated trimethylolpropane triacrylate (ETPTA) macromer/close-packed Al 2O3 nanoparticles (acting as the mechanical framework) and succinonitrile-mediated plastic crystal electrolyte (serving as the ionic transport channel). This chemical/structural uniqueness of the PC-CPE brings remarkable improvement in mechanical flexibility and thermal stability, as compared to conventional carbonate-based liquid electrolytes that are fluidic and volatile. In addition, the PC-CPE precursor mixture (i.e., prior to UV irradiation) with well-adjusted rheological properties, via collaboration with a UV-assisted imprint lithography technique, produces the micropatterned PC-CPE with tunable dimensions. Notably, the cell incorporating the self-standing PC-CPE, which acts as a thermally stable electrolyte and also a separator membrane, maintains stable charge/discharge behavior even after exposure to thermal shock condition (=130 ??C/0.5 h), while a control cell assembled with a carbonate-based liquid electrolyte and a polyethylene separator membrane loses electrochemical activity.close1

Evaluation of the new capture vapourizer for aerosol mass spectrometers (AMS) through laboratory studies of inorganic species

Aerosol mass spectrometers (AMSs) and Aerosol Chemical Speciation Monitors (ACSMs) commercialized by Aerodyne are widely used to measure the non-refractory species in submicron particles. With the standard vapourizer (SV) that is installed in all commercial instruments to date, the quantification of ambient aerosol mass concentration requires the use of the collection efficiency (CE) to correct for the loss of particles due to bounce. A new capture vapourizer (CV) has been designed to reduce the need for a bounce-related CE correction. Two high-resolution AMS instruments, one with a SV and one with a CV, were operated side by side in the laboratory. Four standard species, NH4NO3, NaNO3, (NH4)2SO4 and NH4Cl, which typically constitute the majority of the mass of ambient submicron inorganic species, are studied. The effect of vapourizer temperature (Tv&thinsp;&sim;&thinsp;200&ndash;800 &deg;C) on the detected fragments, CE and size distributions are investigated. A Tv of 500&ndash;550 &deg;C for the CV is recommended. In the CV, CE was identical (around unity) for more volatile species (e.g. NH4NO3) and comparable to or higher than the SV for less-volatile species (e.g. (NH4)2SO4), demonstrating an improvement in CE for laboratory inorganic species in the CV. The detected relative intensities of fragments of NO3&nbsp;and SO4&nbsp;species observed with the CV are different from those observed with the SV, and are consistent with additional thermal decomposition arising from the increased residence time and multiple collisions. Increased residence times with the CV also lead to broader particle size distribution measurements than with the SV. A method for estimating whether pure species will be detected in AMS sizing mode is proposed. Production of CO2(g) from sampled nitrate on the vapourizer surface, which has been reported for the SV, is negligible for the CV for NH4NO3&nbsp;and comparable to the SV for NaNO3.&thinsp;. We observe an extremely consistent fragmentation for ammonium compared to very large changes for the associated anions. Together with other evidence, this indicates that it is unlikely that a major fraction of inorganic species vapourizes as intact salts in the AMS.</p