Microbrittleness and microhardness of basalt and slag glasses after heating at 20–600°C

The change of the mechanical properties of basalt and slag fibres heated at temperatures ranging from 20 to 600°C has been investigated. The Vickers' indenter method was employed for the determination of the variations of microbrittleness and microhardness of glasses. Substantial changes in these parameters were observed even in the range 20–200°C. This phenomenon was associated with the oxidation of Fe(II) ions present in glasses.     

Microscopic derivation of non-Markovian thermalization of a Brownian particle

In this paper, the first microscopic approach to Brownian motion is developed in the case where the mass density of the suspending bath is of the same order of magnitude as that of the Brownian (B) particle. Starting from an extended Boltzmann equation, which describes correctly the interaction with the fluid, we derive systematically via multiple-time-scale analysis a reduced equation controlling the thermalization of the B particle, i.e., the relaxation toward the Maxwell distribution in velocity space. In contradistinction to the Fokker-Planck equation, the derived new evolution equation is nonlocal both in time and in velocity space, owing to correlated recollision events between the fluid and particle B. In the long-time limit, it describes a non-Markovian generalized Ornstein-Uhlenbeck process. However, in spite of this complex dynamical behavior, the Stokes-Einstein law relating the friction and diffusion coefficients is shown to remain valid. A microscopic expression for the friction coefficient is derived, which acquires the form of the Stokes law in the limit where the meanfree path in the gas is small compared to the radius of particle B.Knowing the interest of Matthieu Ernst in the subtle and fundamental problems of kinetic theory, we have the pleasure to dedicate this study to him.     

Polymeric adducts of rhodium(II) tetraacetate with aliphatic diamines: natural abundance 13C and 15N CPMAS NMR investigations

Complexation properties of dimeric rhodium(II) tetracarboxylates have been utilised in chemistry, spectroscopy and organic synthesis. Particularly, the combination of these rhodium salts with multifunctional ligands results in the formation of coordination polymers, and these are of interest because of their gas‐occlusion properties. In the present work, the polymeric adducts of rhodium(II) tetraacetate with flexible ligands exhibiting conformational variety, ethane‐1,2‐diamine, propane‐1,3‐diamine and their N,N′‐dimethyl‐ and N,N,N′,N′‐tetramethyl derivatives, have been investigated by means of elemental analysis, ¹³C CPMAS NMR, ¹⁵N CPMAS NMR and density functional theory modelling. Elemental analysis and NMR spectra indicated the axial coordination mode and regular structures of (1 : 1)_n oligomeric chains in the case of adducts of ethane‐1,2‐diamine, N,N′‐dimethylethane‐1,2‐diamine N,N,N′,N′‐tetramethylethane‐1,2‐diamine and N,N,N′,N′‐tetramethylpropane‐1,3‐diamine. Propane‐1,3‐diamine and N,N′‐dimethylpropane‐1,3‐diamine tended to form heterogeneous materials, composed of oligomeric (1 : 1)_n chains and the additive of dirhodium units containing equatorially bonded ligands. Experimental findings have been supported by density functional theory modelling of some hypothetical structures and gauge‐invariant atomic orbital calculations of NMR chemical shifts. Copyright © 2013 John Wiley & Sons, Ltd.     

Index Theory and Adiabatic Limit in QFT

The paper has the form of a proposal concerned with the relationship between the three mathematically rigorous approaches to quantum field theory: (1) local algebraic formulation of Haag, (2) Wightman formulation and (3) the perturbative formulation based on the microlocal renormalization method. In this project we investigate the relationship between (1) and (3) and utilize the known relationships between (1) and (2). The main goal of the proposal lies in obtaining obstructions for the existence of the adiabatic limit (confinement problem in the phenomenological standard model approach). We extend the method of deformation of Dütsch and Fredenhagen (in the Bordeman-Waldmann sense) and apply Fedosov construction of the formal index—an analog of the index for deformed symplectic manifolds, generalizing the Atiyah-Singer index. We present some first steps in realization of the proposal.     

Oscillations of first-order differential inequalities with deviating arguments

Summary This paper contains some new results on the oscillatory behaviours of differential inequalities (N_z) and (L_z) caused by retarded, advanced and general deviating arguments g_i(t) (i=1,...,n).     

First synthesis of 1,1-ferrocene bis-aminophosphonic esters

The series of aminophosphonates bearing the 1,1^′-bis-substituted ferrocenyl moiety was obtained by the addition of dialkyl phosphites to an azomethine bond of Schiff bases derived from 1,1^′-ferrocene-bis-carboxaldehyde. This addition led to both diastereoisomeric forms demonstrating its behaviour to be contrary to the addition to terephthalic Schiff bases, which led exclusively to a meso-form.     

Solvent influence on the rotational isomerism in terephthalaldehyde

Experimental and theoretical studies were carried out in order to investigate the rotational isomerism of terephthalaldehyde. The dipole moment measurements and infrared spectroscopy in Ar matrix and using various solvents were performed experimentally. In order to supplement the experimental study, both static and dynamical theoretical calculations were performed. IR spectra and potential energy distribution (PED) were calculated for both cis and trans isomers of terephthalaldehyde in gas phase using B3LYP/6-31G(d,p) level of theory. Further calculations consisted of conformational analysis were performed in order to estimate the rotational barrier and relative stabilities of isomers. The DFT theory with B3LYP functional and four double-zeta and triple-zeta basis sets served as framework for this part of calculations. Semiempirical AM1 and PM3 methods were also used for gas-phase modeling. Molecular dynamics using MM3 force field was applied to study the preferences of solvent molecules’ orientation around the studied molecule. Additionally, the effect of solvent polarity on the Gibbs energy of the trans ⇌ cis equilibrium was analyzed in terms of the continuum dielectric medium models.     

Optimization of background electrolytes for capillary electrophoresis: II. Computer simulation and comparison with experiments

A mathematical and computational model described in the previous paper (Gas, B., Coufal, P., Jaros, M., Muzikár, J., Jelínek, L., J. Chromatogr. A 2001, 905, 269-279) is adapted, algorithmized, and a computer program PeakMaster having a status of freeware (http://natur.cuni.cz/ approximately gas) is introduced. The model enables optimization of background electrolyte (BGE) systems for capillary zone electrophoresis. The model allows putting to use uni- or di- or trivalent electrolytes and allows also for modeling highly acidic or alkaline BGEs. It takes into account the dependence of ionic mobilities and dissociation of weak electrolytes on the ionic strength. The model calculates the effective mobility of analytes and predicts parameters of the system that are experimentally available, such as the transfer ratio, which is a measure of the sensitivity in the indirect UV detection or the molar conductivity detection response, which expresses the sensitivity of the conductivity detection. Further, the model enables evaluation of a tendency of the analyte to undergo electromigration dispersion or peak broadening. The suitability of the model is verified by comparison of the predicted results with experiments, even under conditions that are far from ideal (under extreme pH and a high ionic strength).