The Geometry and Moduli of K3 Surfaces

These notes will give an introduction to the theory of K3 surfaces. We begin with some general results on K3 surfaces, including the construction of their moduli space and some of its properties. We then move on to focus on the theory of polarized K3 surfaces, studying their moduli, degenerations and the compactification problem. This theory is then further enhanced to a discussion of lattice polarized K3 surfaces, which provide a rich source of explicit examples, including a large class of lattice polarizations coming from elliptic fibrations. Finally, we conclude by discussing the ample and Kahler cones of K3 surfaces, and give some of their applications.Comment: 34 pages, 2 figures. (R. Laza, M. Schutt and N. Yui, eds.

Emissions treatment apparatus and a method for treating emissions

An emissions treatment apparatus includes a first mechanism arranged to receive an exhaust gas, wherein the first mechanism is supplied with a first substance arranged to react with a first exhaust compound to process the exhaust gas, the first substance being chemically derived from an electrolyte source. The emissions treatment apparatus further comprises a second mechanism arranged to receive the exhaust gas after its reaction with the first exhaust compound; wherein the second mechanism receives a second substance arranged to react with a second exhaust compound to further process the exhaust gas, the second substance being chemically derived from an electrolyte source

Electrospray mass spectrometry: Application of ion evaporation theory to amino acids

We describe the result of applying the ion evaporation theory to a series of amino acids. The very good correlation (r = 0.98) of the natural logarithms of protonated molecule intensities observed by electrospray with the difference between the hydration free energies of molecules and the gas-phase binding free energies of molecules and protons in amino acids is consistent with the ion evaporation model. It seems that the difference in the protonated molecule intensities of amino acids obtained by electrospray can be explained by a scheme in which protonated molecules in the liquid phase are extracted into the gas phase after a charged droplet is formed

Europium induced point defects in SrSnO3-based perovskites employed as antibacterial agents

International audienceThe antibacterial activity of Eu3+-doped SrSnO3-type materials against Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative) bacteria is described. Two Eu3+-doped SrSnO3 perovskites - (SrEu)SnO3 and Sr(SnEu)O3 - were synthesised by a modified-Pechini method and characterised by XRD, FT-IR, FE-SEM, HR-STEM/EDX, BET, Photoluminescence (PL), UV-Vis, Q-band EPR and XPS to understand the impact of Eu doping on the materials’ properties. Structural characterisations indicated that the desired perovskite phase completely crystallised after calcination at 700 °C. Long and short-range structural changes were observed as a function of the site-doping with Eu and calcination temperature. Small specific surface area, which varied from 8.09 to 13.28 m2/g, was observed for the samples. Nonetheless, the formation of nanoparticles under 10 nm, clusters of nanoparticlesandgt; 100 nm, and nanorods with 100–600 nm × 10–50 nm (length × width) was evidenced. Eu3+ doping led to an increase of Sn2+ and oxygen vacancies in SrSnO3 lattice, playing an essential role in the antibacterial activity. Reduced Eu2+ species were also observed. The samples had activity below 5 % against Escherichia coli, whereas (SrEu)SnO3 displayed an efficiency of 100 % after 24 h against Staphylococcus aureus at a concentration of 1 mg/mL. Our results demonstrate that a specific chemical doping with Eu induces the formation of distinct point defect (Sn2+, Eu2+ and VO•) in the materials, which promoted a negative surface charge that seems to have improved the redox ability and, therefore, enhanced the biocide property

Defect engineering boosted ultrahigh thermoelectric power conversion efficiency in polycrystalline SnSe

Two-dimensional (2D)-layered atomic arrangement with ultralow lattice thermal conductivity and ultrahigh figure of merit in single-crystalline SnSe drew significant attention among all thermoelectric materials. However, the processing of polycrystalline SnSe with equivalent thermoelectric performance as single-crystal SnSe will have great technological significance. Herein, we demonstrate a high zT of 2.4 at 800 K through the optimization of intrinsic defects in polycrystalline SnSe via controlled alpha irradiation. Through a detailed theoretical calculation of defect formation energies and lattice dynamic phonon dispersion studies, we demonstrate that the presence of intrinsically charged Sn vacancies can enhance the power factor and distort the lattice thermal conductivity by phonon-defect scattering. Supporting our theoretical calculations, the experimental enhancement in the electrical conductivity leads to a massive power factor of 0.9 mW/mK2 and an ultralow lattice thermal conductivity of 0.22 W/mK through the vacancy-phonon scattering effect on polycrystalline SnSe. The strategy of intrinsic defect engineering of polycrystalline thermoelectric materials can increase the practical implementation of low-cost and high-performance thermoelectric generators