Hydroxylation and dehydroxylation at Cu(III) surfaces

X-ray photoelectron spectroscopy has shown how both chemisorbed oxygen present at a Cu(III) surface and nitric oxide introduced into the gas phase can induce hydroxylation of the surface from an adlayer of molecularly adsorbed water at 80 K. The interaction of water vapour with a clean Cu(III) surface is also reported.     

Disjoint factors of diameter two in complete graphs

Let f(k) be the least positive integer n such that the complete graph with n vertices has a decomposition into k factors of diameter two. It is well known that f(2) = 5, f(3) = 12 or 13, and 4k ?1 ? f(k) ? 7k for every integer k ? 4. In the present paper it is proved that 6k ? 52 ? f(k) ? 6k for every integer k ? 2. (For k ? 370 also a better lower estimate of f(k) is given.)     

Molecular aggregation of rhodamine dyes in dispersions of layered silicates: influence of dye molecular structure and silicate properties

The molecular aggregation of six rhodamine dyes (rhodamine 560, B, 3B, 19, 6G, 123) in layered silicate (saponite and fluorohectorite) dispersions was investigated by using visible (vis) spectroscopy. The dye molecular aggregation was influenced by the properties of both the silicates and the dyes themselves. The layer charge of the silicates enhanced the molecular aggregation of the hydrophilic, cationic dyes. The presence of a carboxyl acid group in the dye molecules inhibited adsorption of the dyes on the surface of fluorohectorite, a silicate with a high charge density. A lower or no adsorption could be observed by vis spectroscopy. Strong association of the dyes to the silicate surface led to remarkable changes in the dye spectra, mainly due to the molecular aggregation. Dye assemblies initially formed after mixing the dye solutions with silicate dispersions were unstable. Decomposition of the dye molecular assemblies, and the formation of new species or molecular aggregate rearrangements, were studied on the bases of time-difference spectra. The reaction pathways were specific, not only for the dyes, depending upon their molecular structure and properties, but also on the silicate substrates.     

Optical sensing system for ATP using porphyrin-alkaloid conjugates

Tetrabrucin-porphyrin as a sensor for ATP was designed and tested; selectivity for ATP was proved in the presence of ADP and AMP.     

Hereditary Coreflective Subcategories of the Categories of Tychonoff and Zero-Dimensional Spaces

In this paper the structure of hereditary coreflective subcategories in the categories Tych of Tychonoff and ZD of zero-dimensional spaces is studied. It is shown that there are (many) hereditary additive and divisible subcategories in Tych and ZD which are not coreflective. Moreover, if ${\mathcal{A}}$ is an epireflective subcategory of the category Top of topological spaces which is not bireflective and ${\mathcal{B}}$ is an additive and divisible subcategory of ${\mathcal{A}}$ which is not coreflective, then the coreflective hull of ${\mathcal{B}}$ in ${\mathcal{A}}$ is not hereditary. It is also shown, in the case of Tych under Martin’s axiom or under the continuum hypothesis, that if ${\mathcal{B}}$ is a hereditary coreflective subcategory of Tych (ZD), then either the topologies of all spaces belonging to ${\mathcal{B}}$ are closed under countable intersections or it contains all Tychonoff spaces (zero-dimensional spaces) with Ulam nonmeasurable cardinality.     

M−O Bonding Beyond the Oxo Wall: Spectroscopy and Reactivity of Cobalt(III)‐Oxyl and Cobalt(III)‐Oxo Complexes

Terminal oxo complexes of late transition metals are frequently proposed reactive intermediates. However, they are scarcely known beyond Group 8. Using mass spectrometry, we prepared and characterized two such complexes: [(N4Py)Co^III(O)]⁺ ( 1 ) and [(N4Py)Co^IV(O)]²⁺ ( 2 ). Infrared photodissociation spectroscopy revealed that the Co?O bond in 1 is rather strong, in accordance with its lack of chemical reactivity. On the contrary, 2 has a very weak Co?O bond characterized by a stretching frequency of ≤659 cm^?1. Accordingly, 2 can abstract hydrogen atoms from non‐activated secondary alkanes. Previously, this reactivity has only been observed in the gas phase for small, coordinatively unsaturated metal complexes. Multireference ab‐initio calculations suggest that 2 , formally a cobalt(IV)‐oxo complex, is best described as cobalt(III)‐oxyl. Our results provide important data on changes to metal‐oxo bonding behind the oxo wall and show that cobalt‐oxo complexes are promising targets for developing highly active C?H oxidation catalysts.     

Mixed 2D molecular systems: Mechanic, thermodynamic and dielectric properties

Study of Langmuir monolayers consisting of stearic acid (SA) and dipalmitoylphosphatidylcholine (DPPC) molecules was done by surface pressure-area isotherms (π-A), the Maxwell displacement current (MDC) measurement, X-ray reflectivity (XRR) and atomic force microscopy (AFM) to investigate the selected mechanic, thermodynamic and dielectric properties based on orientational structure of monolayers. On the base of π-A isotherms analysis we explain the creation of stable structures and found optimal monolayer composition. The dielectric properties represented by MDC generated monolayers were analyzed in terms of excess dipole moment, proposing the effect of dipole-dipole interaction. XRR and AFM results illustrate deposited film structure and molecular ordering.     

Empirical distribution of daily stock returns of selected developing and emerging markets with application to financial risk management

Central European Journal of Operations Research - The paper deals with the analysis of the empirical distribution of returns of selected market indices of developed and developing markets in...