Rapid solidification processing in molten salts chemistry: X-ray analysis of deeply undercooled cryolite-alumina melts

Rapid solidification processing (cooling rate from the interval 10⁵–10⁶ K s⁻¹) was used to prepare deeply undercooled cryolite-alumina melts. Such prepared samples were analyzed by the XRD method. Besides cryolite, XRD patterns belonging to ι-Al₂O₃ were recorded. The influence of annealing on the XRD patterns of deeply undercooled melts was also investigated.     

Syntheses,X-ray,MS, NMR and CD structure determination of nickel(II) complexes of Schiff bases of (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide and aromatic α-amino acids

A preparative procedure for the synthesis of an important chiral synthon of side-chain protected tyrosine was developed and optimised for the minimisation of nickel salts waste. While preparing a similar side-chain protected tryptophan synthon, an unexpected low stability was found of the Boc-protective group of the tryptophan aromatic nitrogen during purification on silica gel. X-ray crystal structure determination, tandem mass spectrometry (MS/MS) and NMR were applied for the elucidation of the structures of the prepared complexes and by-products. Stereochemistry of products of α-methylation of the complexes was assessed using a model tyrosine-derived compound.     

Transient time in homogeneous nucleation

The problem of the transient time in nucleation is studied. The size-dependent transient time at a constant temperature is defined and the approximate analytical solution is found and compared with the exact numerical solution for the model Li₂O.2 SiO₂ melt. It is shown that the analytical solution for the size-dependent transient time is in agreement with the numerical result.     

Bottlebrush‐shaped copolymers with cellulose diacetate backbone by a combination of ring opening polymerization and ATRP

Graft copolymers with cellulose diacetate (CDA) backbone and both the poly(ε‐caprolactone) and polystyrene, or poly(butyl acrylate) or PMMA grafts were prepared by two‐step process. First, ε‐caprolactone (CL) was polymerized by ring‐opening polymerization (ROP) initiated with CDA, partly funcionalized with 2‐bromo‐isobutyryl groups (degree of functionalization was 0.5). The p(CDA‐g‐CL) copolymers were used in the second step as polyfunctional macroinitiators of ATRP of the vinyl monomer, giving densely grafted copolymers with polyester and PSt, or PBuA, or PMMA grafts. The prepared copolymers were characterized by SEC, some of them also by FTIR spectroscopy and atomic force microscopy (AFM). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 564–573, 2008     

Lie ideals and (\alpha ,\beta )-derivations of *-prime rings

Let \((R,*)\) be a \(2\)-torsion free \(*\)-prime ring with involution \(*\), \(L\ne \{0\}\) be a \(*\)-Lie ideal of \(R\). An additive mapping \(d:R\rightarrow R\) is called an \((\alpha ,\beta )\)-derivation of \(R\) such that \(d(xy)=d(x)\alpha (y)+\beta (x)d(y)\). In the present paper, we shall show that when \(L\) satisfies any of several identities involving \(d\), then \(L\) is central.     

Activity of polymer supported cobalt catalyst in the Bray-Liebhafsky oscillator

The infuence of poly-4-vinylpyridine-co-divinylbenzene-Co²⁺ catalyst on the Bray-Liebhafsky (BL) oscillator used as the matrix for establishing catalyst’s activity was analyzed. The addition of the catalyst do not change the dynamics of the reaction in the BL matrix, but the periods of the oscillatory evolution as well as the preoscillatory period (τ₁) and the duration from the beginning of the reaction to the end of the oscillatory state (τ_end). All experimental results are simulated satisfactory. The article is published in the original.     

New Approach to Mechanism of Action of Paclitaxel by Means of BioArena Studies

JPC – Journal of Planar Chromatography – Modern TLC - The accumulation of hydrogen peroxide (H2O2) is an early and crucial step in paclitaxel-induced cancer cell death before commitment...     

States on families of subspaces of pre-Hilbert spaces

We present six families of closed subspaces of a pre-Hilbert space and we show that if arbitrary, one of them possesses at least one completely additive state, then the pre-Hilbert space is complete.     

Generic hyperbolicity for reaction diffusion equations on symmetric domains

Summary The problem of generic hyperbolicity for reaction diffusion equations with Dirichlet boundary conditions on a ball inR ⁿ is studied. It is proved that while hyperbolicity is not a generic property, radially symmetric solutions are generically hyperbolic.

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Zusammenfassung Das Problem der generischen Hyperbolizität für Reaktion-Diffusionsgleichungen mit Dirichletschen Randbedingungen in einer Kugel imR ⁿ wird betrachtet. Es wird bewiesen, daß radialsymmetrische Lösungen generisch symmetrische sind, während Hyperbolizität nicht eine generische Eigenschaft ist.

     

Non-stationary crystallization in simple glass-forming materials

A crystal distribution function is established during the crystallization process of simple glass-forming melts on the basis of the numerical computation of the kinetic equation in a non-stationary regime for constant and non-constant temperature. Nucleation rate and time-temperature-transformation curves are determined from the calculations of the crystal distribution function at various constant temperatures for various parameters of the system (the dependence on the difference of the chemical potentials, the dependence on the surface energy etc.).