Thermal and optical behaviour of octa-alkoxy substituted phthalocyaninatovanadyl complexes

This paper deals with the synthesis of vanadyl phthalocyanines substituted with eight alkoxy chains in the peripheral (2, 3, 9, 10, 16, 17, 23, 24) positions. The alkoxy chain length was varied, and octa-octyloxy (C₈H₁₇O), octa-dodecyloxy (C₁₂H₂₅O) and octa-hexadecyloxy (C₁₆H₃₃O) substituted vanadyl phthalocyanine complexes were prepared. Studies by polarizing optical microscopy and small angle X-ray diffraction (XRD) revealed that all the complexes are liquid crystalline and that these metallomesogens exhibit a columnar phase. The symmetry of the 2D lattice is rectangular, with a ^c2^mm space group, as determined by the indexation of the XRD reflections; hence a rectangular columnar phase (Colr) was assigned. A double periodicity, although weak, along the axis of the columns was found, which indicates some degree of pairing or dimerization. A tentative explanation based on an antiferroelectric stacking is given. Transition enthalpies were determined by differential scanning calorimetry. The compounds start to decompose above 250°C before reaching the clearing temperatures. A significant bathochromic shift of the Q-band in the UV/Vis spectra of the vanadyl complexes compared with the metal-free ligands and other metallophthalocyanines (M=Co^II, Ni^II, Cu^II, Zn^II) was also observed.     

Nachweis und Bestimmung kleiner Mengen von Mangan besonders in organischen Substanzen

Ohne Zusammenfassung     

Polycatenar, bent-core pyridines and their discotic complexes with silver(I)

New, bent-core, polycatenar pyridine mesogens are described. Binding to silver(I) leads to complexes properly described as discotic.     

A Hilbert-Vlasov code for the study of high-frequency plasmabeatwave accelerator

High-frequency beatwave simulations relevant to the University of California at Los Angeles (UCLA) experiment with relativistic eulerian hybrid Vlasov code are presented. These Hilbert-Masov simulations revealed a rich variety of phenomena associated with the fast particle dynamics induced by beatwave experiment for a high ratio of driver frequency to plasma frequency ω_pump/ω_plasma ≈33. The present model allows us to extend detailed modeling to frequency ratios greater than the current practical maximum of 10 or so, for Vlasov or particle-in-cell (PIC) codes, by replacing the Maxwell equations by mode equations for the electromagnetic Vlasov code. Numerical results, including beat frequency chirping (i.e., pump frequency linearly decreasing with time), show that the amplitude limit due to relativistic detuning can be enhanced with accelerated particles up to the ultrarelativistic energies with a high-acceleration gradient of more than 25 GeV/m     

Moduli of objects in dg-categories

The purpose of this work is to prove the existence of an algebraic moduli classifying objects in a given triangulated category.To any dg-category T (over some base ring k), we define a D⁻-stack MT in the sense of [Toën B., Vezzosi G., Homotopical algebraic geometry II: Geometric stacks and applications, Mem. Amer. Math. Soc., in press], classifying certain Top-dg-modules. When T is saturated, MT classifies compact objects in the triangulated category [T] associated to T. The main result of this work states that under certain finiteness conditions on T (e.g. if it is saturated) the D⁻-stack MT is locally geometric (i.e. union of open and geometric sub-stacks). As a consequence we prove the algebraicity of the group of auto-equivalences of saturated dg-categories. We also obtain the existence of reasonable moduli for perfect complexes on a smooth and proper scheme, as well as complexes of representations of a finite quiver.     

No limit cycle in two species second order kinetics

We give a new and direct proof of the nonexistence of limit cycle in a bimolecular system and the characterization of the unique bimolecular oscillator. The proof is an application of classification theorems on vector fields with homogeneous second degree polynomial perturbations.     

La0.7Ce0.3MnO3 epitaxial films fabricated by a pulsed laser deposition method

La_0.7Ce_0.3MnO₃ epitaxial films were successfully fabricated via a pulsed laser deposition method by controlling the experimental conditions. A series of experiments with varying the oxygen pressure and the substrate temperature demonstrated that the use of appropriate conditions is crucial for fabricating the epitaxial thin films. The existence of such suitable conditions was thermodynamically interpreted in terms of the stability of Mn²⁺ ion. Both XRD and EPMA measurements indicated that La_0.7Ce_0.3MnO₃ thin films fabricated herein form single phases, although it was difficult to present the direct experimental evidence to prove that Ce ion can really exist within the perovskite structure. The resultant films with oxygen annealing showed a metal-insulator transition and ferromagnetic property with Curie temperature of 275 K.