Thermoluminescence measurements of liquid crystal azomethines and poly(azomethines) with different shapes as thermo-detectors

We have explored the thermoluminescence (TL) properties of a few series of liquid crystal unsymmetrical and symmetrical azomethines and poly(azomethines) with different shapes. Rod-, bent- and star-shaped compounds were investigated as thermoluminescent detectors. All of the investigated compounds, except ASB3, AG2 and PAZ2, exhibited mesomorphic behavior. The thermoluminescence studies have shown that molecular structure of the compound along with shape influenced the TL properties of azomethines and poly(azomethines). Thermoluminescence intensity (I), temperature of maximum TL (T), activation energy values (E) and frequency factor (s) were detected. For the first time, to the best of our knowledge, thermoluminescence properties of liquid crystalline azomethines and polyazomethines were described and compared in this article.     

Finer geometric rigidity of limit sets of conformal IFS

We consider infinite conformal iterated function systems in the phase space with . Let be the limit set of such a system. Under a mild technical assumption, which is always satisfied if the system is finite, we prove that either the Hausdorff dimension of exceeds the topological dimension of the closure of or else the closure of is a proper compact subset of either a geometric sphere or an affine subspace of dimension . A similar dichotomy holds for conformal expanding repellers.

     

Decomposition of Complete Bipartite Even Graphs into Closed Trails

We prove that any complete bipartite graph K _a,b , where a, b are even integers, can be decomposed into closed trails with prescribed even lengths.     

Lithium intercalation into CrO<Subscript>3</Subscript>-GIC and its derivatives

Graphite intercalation compound with chromium trioxide (CrO₃-GIC) was used as a precursor for new graphite composites. By heating CrO₃-GIC at 800 °C in air a composite material, expanded graphite/Cr₂O₃, was obtained, whereas further heating of this composite at 1000 °C in the stream of hydrogen/argon mixture led to the reduction of Cr₂O₃ to chromium carbide (Cr₃C₂). A new material thus obtained was expanded graphite/Cr₃C₂ composite. The chromium species having catalytic properties gave rise to the improvement of the crystal structure of expanded graphite. All materials were tested as anode materials for lithium-ion cell. It was found that graphitic material treated in H₂/Ag at 1000 °C has greater reversible capacity in comparison to the original graphite and the shape of the charge/discharge curve shows very well-defined stage structure which supports the crystallographic data.Presented at the 3rd International Meeting Advanced Batteries and Accumulators, June 16th–June 20th, Brno, Czech Republic     

Topological Ergodicity of Real Cocycles over Minimal Rotations

 We prove that for each minimal rotation on a compact metric group and each topological cocycle , either φ is a topological coboundary, or is topologically ergodic, or the partition into orbits is the decomposition of into minimal components. As an application, we generalize a result by Glasner and show that if is a minimal topologically weakly mixing flow, then whenever φ is universally ergodic the minimal map

Structure of a C26H28 alkene formed via titanium-promoted reductive dimerization of 4-(spirocyclopropyl)-pentacyclo[5.4.0.02,6.03,10.05,9]undecan-8-one

A spiro-fused C₂₆H₂₈ cage≓ dimer hydrocarbon contains two three-membered rings, two four-membered rings, eight five-membered rings, and two six-membered rings. The molecule is calculated by molecular mechanics to have 902 kJ/mol of strain energy distributed primarily between angle strain (457 kJ/mol) and torsional interactions (368 kJ/mol). Molecular mechanics calculations and a geometry-optimized ab initio calculation are used to analyze the bond lengths and bond angles in the molecule. There is one major discrepancy between observed and calculated distances.     

Relativistic and correlation corrections to electron affinities of alkali and halogen atoms

Electron affinities (EAs) of alkali and halogen atoms have been calculated using Hartree-Fock and Dirac-Hartree-Fock methods. Comparing the results with the experimental values, relativistic and correlation corrections to EAs have been estimated. In the case of alkalines correlation correction constitute 110%–120% of the experimental EA values. In the case of halogens the corresponding numbers are 30%–60%. Relativistic effects are negligibly small for alkalines but significant for halogens (40% of the experimental value for At).     

Geometric H/D isotope effects and cooperativity of the hydrogen bonds in porphycene.

We investigate the primary, secondary, and vicinal hydrogen/deuterium (H/D) isotope effects on the geometry of the two intramolecular hydrogen bonds in porphycene. Multidimensional potential energy surfaces describing the anharmonic motion in the vicinity of the trans isomer are calculated for the different symmetric (HH/DD) and asymmetric (HD) isotopomers. From the solution of the nuclear Schr?dinger equation the ground-state wavefunction is obtained, which is further used to determine the quantum corrections to the classical equilibrium geometries of the hydrogen bonds and thus the geometric isotope effects. In particular, it is found that the hydrogen bonds are cooperative, that is, both expand simultaneously even in the case of an asymmetric isotopic substitution. The theoretical predictions compare favorably with NMR chemical-shift data.     

Interaction of dicarboxylic metalloporphyrins with liposomes. The effect of pH on membrane binding revisited

The acid-base properties of Zn-hematoporphyrin IX (ZnHP) and Zn-mesoporphyrin IX (ZnMP) and the effect of pH on their binding to liposomes have been studied. The ionization constants for the two carboxylate groups of ZnHP were calculated by principal component analysis and are 5.7 +/- 0.1 and 6.9 +/- 0.05. The neutral species and the mono- and dianionic forms all bind to liposomes, but a strong pH effect on the binding constant was observed for both the investigated compounds. We also observed a decrease in the binding of the two anionic species when the membranes carried a negative charge. These results indicate that the porphyrins partition into the membrane with their carboxylic moieties near the lipid-water interface so that their deprotonation, leading to a charged molecule, does not prevent the insertion of the tetrapyrrole ring into the lipid environment of neutral liposomes.