On Solvability of Boundary Value Problems for Kinetic Operator-Differential Equations

We study solvability of boundary value problems for the so-called kinetic operator-differential equations of the form B(t)u _t ?L(t)u = f, where L(t) and B(t) are families of linear operators defined in a complex Hilbert space E. We do not assume that the operator B is invertible and that the spectrum of the pencil L ?λ B is included into one of the half-planes Re λ < a or Re λ > a \({(a\in {\mathbb{R}})}\) . Under certain conditions on the above operators, we prove several existence and uniqueness theorems and study smoothness questions in weighted Sobolev spaces for solutions.     

N-Tris[(2-aminoethyl)-2-(diphenylphosphoryl) acetamide)] — novel CMPO tripodand: synthesis,extraction studies and luminescent properties of lanthanide complexes

A ligand system containing three carbamoylmethylphosphine oxide (CMPO) moieties attached to a tripodal platform with a central nitrogen atom has been synthesized for metal complexation and extraction from neutral and nitric acid solutions. Liquid-liquid extractions performed for Ln(III), both from neutral and acidic media, show excellent extraction properties which exceeded those for the known mono- and di-CMPO derivatives as well as the related tripodands. A considerable enhancement of the D_Ln values was observed in the presence of IL ([bmim][Tf₂N]) in the organic phase towards lanthanide ions from 3M HNO₃ solutions. The protonation of the central amine nitrogen atom of the ligand 1 in the acidic media provides also the effective extraction of the perrhenate anionic complexes. The europium complexes formed by mono- and tris-CMPO ligands in the solid state, as well as Eu(III) and Tb(III) complexes generated in solutions, possess intensive luminescence at 300K     

A Liouville comparison principle for sub- and super-solutions of the equation w t −Δ p (w) = |w| q-1 w

We establish a Liouville comparison principle for entire weak sub- and super-solutions of the equation (*) w _t ?Δ _p (w) =  |w| ^q-1 w in the half-space ${\mathbb {S}= \mathbb {R}^1_+\times \mathbb {R}^n}$ , where n ≥ 1, q > 0, and ${ \Delta_p(w) := {\rm div}_x \left(|\nabla_x w|^{p-2}\nabla_x w \right)}$ , 1 < p ≤ 2. In our study we impose neither restrictions on the behaviour of entire weak sub- and super-solutions of (*) on the hyper-plane t = 0, nor any growth conditions on their behaviour and on that of any of their partial derivatives at infinity. We prove that if ${1< q \leq p-1+\frac {p}{n}}$ and u and v are, respectively, an entire weak super-solution and an entire weak sub-solution of (*) in ${\mathbb {S}}$ which belong, only locally in ${\mathbb {S}}$ , to the corresponding Sobolev space and are such that u ≥  v, then u ≡ v. The result is sharp. As direct corollaries we obtain known Fujita-type and Liouville-type theorems.     

NMR T1–T2 correlation analysis of molecular absorption inside a hardened cement paste containing silanised silica fume

ABSTRACT

The influence of silanised silica fume addition on the pore size distribution and wettability of white cement paste was investigated using T₁–T₂ correlation nuclear magnetic resonance (NMR) relaxometry. Surface silanisation of silica fume particles was achieved by the hydrolysis reaction of APTES (3-Aminopropyltriethoxysilane) and condensation of the silanol functional groups on the surface. The methods used for characterisation of the silanised silica fume particles were scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). By adding silanised silica fume to the cement paste, the accessibility of water molecules to the porous system becomes restricted, leading to a lower permeability in comparison with the unmodified cement paste. Differential scanning calorimetry (DSC) measurements on the cement pastes saturated with Octamethylcyclotetrasiloxane confirm also that the size of inter-C–S–H and capillary pores is not influenced by the addition of silica fume in a detectable manner.     

On a Liouville-type comparison principle for solutions of quasilinear elliptic inequalities

We characterize in terms of monotonicity basic properties of quasilinear elliptic partial differential operators which make it possible to obtain a Liouville-type comparison principle for entire solutions of quasilinear elliptic partial differential inequalities of the form A(u)+|u|^q?1u?A(v)+|v|^q?1v, which belong only locally to the corresponding Sobolev spaces on $\text{R}{}^{\mathrm{n}}\text{,}\text{n?2}$. We establish that such properties are inherent for a wide class of quasilinear elliptic partial differential operators. Typical examples of such operators are the p-Laplacian and its well-known modifications for 1<p?2. To cite this article: V.V. Kurta, C. R. Acad. Sci. Paris, Ser. I 336 (2003).     

Rheological and photophysical investigations of chromonic-like supramolecular mesophases formed by luminescent iridium(III) ionic complexes in water

Luminescent complexes with general formula [(C^N)₂Ir(N^N)]OCOCH₃, where C^N = 2-phenylpyridine (ppy) and N^N = 2,2?-bipyridine (bpy), self-assemble into ordered ‘soft’ viscous mesophases of chromonic type. By changing the ancillary ligand with 1,10-phenanthroline (phen), a new mesomorphic complex was obtained. The self-assembly into ordered liquid crystalline phases of chromonic type in water was investigated by comprehensive rheological and photophysical studies. By changing the ancillary ligand bpy with phen, assembly into smaller, more symetric aggregates is favoured, resulting in lower viscosity and more dynamic mesophase.     

Synthesis and spectroscopic investigations of Rh(III) and Pd(II) complex compounds with N-(pyridine-2-yl)morpholine-4-carbothioamide

The present paper describes the synthesis and spectral properties of Rh(III) and Pd(II) coordination compounds with N-(pyridine-2-yl)morpholine-4-carbothioamide (PMCTA). The compounds have the general composition [RhL₂Cl₂]Cl · C₂H₅OH (1), [PdL₂]Cl₂ (2), [PdL₂](ClO₄)₂ · 2C₃H₆O (2a), [PdLCl₂] · 2H₂O (3). All complexes were characterized by elemental analysis, IR, ¹H NMR, ¹³C NMR, XPS and UV–Vis spectra. It has been shown that PMCTA behaves as a bidentate (N,S)-ligand, forming six membered metallocycles and coordinating to the metal ion through the carbothioamide sulfur atom and the pyridine nitrogen atom. The UV–Vis spectra suggest that the Pd(II) complexes are square planar, while the Rh(III) complex has an octahedral geometry. The molecular structure of the Pd(II) complex with PMCTA (M:L = 1:2) was determined by single-crystal X-ray diffraction.     

Synthesis of pyrazolo- and [1,2,4]triazolo-[1,5-а]quinolin-9-ols by cycloaddition to 8-hydroxyquinoline N-imide

Chemistry of Heterocyclic Compounds - The reaction of 1-amino-8-hydroxyquinolinium mesitylenesulfonate with alkenes and alkynes containing electron-withdrawing substituents was performed in...     

A versatile gas-flow proportional counter for Mössbauer spectroscopy

We discuss the need for neutral atom traps instead of atomic beams for the high-precision spectroscopic comparison of anithydrogen and hydrogen. We also describe recent proposals and advances towards a new trap for hydrogen and briefly discuss traps for antihydrogen.     

Oxygen species on the silver surface oxidized by MW-discharge: Study by photoelectron spectroscopy and DFT model calculations

A polycrystalline silver surface has been studied by synchrotron radiation photoelectron spectroscopy after deep oxidation by microwave discharge in an O₂ atmosphere. Oxidized structures with high oxygen content, AgO_x with x > 1, have been found on the silver surface after oxidation at 300–400 K. The line shapes observed in the O1s spectra were decomposed into five components and indicated that complex oxidized species were formed. An analysis of the oxidized structures with binding energies, Е_b(O1s), greater than 530 eV pointed to the presence of both Ag–O and O–O bonds. We have carried out a detailed experimental study of the valence band spectra in a wide spectral range (up to 35 eV), which has allowed us to register the multicomponent structure of spectra below Ag4d band. These features were assigned to the formation of Ag–O and O–O bonds composed of molecular (associative) oxygen species. DFT model calculations showed that saturation of the defect oxidized silver surface with oxygen leads to the formation of associative oxygen species, such as superoxides, with electrophilic properties and covalent bonding. The high stability of oxygen-rich silver structures, AgO_x, can be explained by the formation of small silver particles during the intensive MW oxidation, which can stabilize such oxygen species.