Materials Literature
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It is well known that the software Surface Evolver (SE) models the geometry of minimal surface area structures such as a foam. Here we have modelled with SE the gas-diffusion phenomenon responsible for the coarsening of liquid foams. We took as an initial condition, a real reconstructed foam obtained by optical tomogr…
Among the copper base shape memory alloys the most popular are CuZnAl alloys which however show several features like: tendency to stabilisation, limitation of the effect to low temperatures, lattice defects multiplication after numerous cycling and low decomposition temperatures. This defines the directions of invest…
The new compound hexacaesium hexatellurido digermanate(III), Cs 6 Ge 2 Te 6 , has been prepared by reacting the elements in a stoichiometric ratio at 923 K in an evacuated silica glass tube. The title compound crystallizes as black columns and is isostructural to K 6 G e 2 Te 6 (C2/c, a = 17.027(2), b = 14.237(1), c =…
Conductivity measurements on a smectic liquid crystal with terminal diol-groups are reported. The average conductivity in the liquid crystalline state exceeds the conductivity of the isotropic melt by a factor of 2. This strongly unusual behaviour supports the assumption of fast protonic conductivity in smectic diols,…
The excited-state complex (exciplex) formation that results from the photoinduced interaction of water-soluble cationic copper(II) 5,10,15,20-tetrakis[4-(N-methylpyridyl)]porphyrin [Cu(TMpy-P4)] with calf-thymus DNA has been studied in detail by resonance Raman (RR) spectroscopy using both ∼10 ns and ∼50 ps laser puls…
Raman spectra of the sodium salts of uridine and deoxyuridine monophosphoric acid, Na2(3′-UMP)·4H2O, Na2(5-UMP)·7H2O and Na2(5′-dUMP)·5H2O, and the cadmium salt, [Cd(5′-UMP)(H2O)2]·2H2O, were examined. Several spectral differences were observed owing to nucleoside conformational differences in the uridine residue. The…
Abstract The stability constants of several divalent first row transition and trivalent lanthanide metal complexes were determined by capillary electrophoresis (CE) methods. Four different approaches, i.e. direct formation, ligand exchange, metal exchange and metal‐ligand double exchange were developed. To verify if t…
HPLC analysis of the methanol-extractable fractions of polymers was used to study the formation of cyclic oligomers during the non-activated anionic polymerization of 6-hexanelactam initiated by sodium or magnesium salt of 6-hexanelactam and ethylmagnesium bromide at 190°C. It was demonstrated that the nature of the c…
A novel two-step method combining rubbing and UV-irradiation based on ladderlike polysilsesquioxanes (LPS) containing cinnamate and azobenzene side chains was developed to obtain alignment layers which features a high surface pretilt angle and good stability. At the first step, a low pretilt angle of 1–3° was generate…
We have performed a preliminary study by light transmission of the electro-optical behaviour of several cells prepared either from hydroxypropylcellulose (HPC) or HPC with cellulose acetate (CA) (1% w/w) cross linked in both cases with 1,4-diisobutanocianaie (BDI) (7%w/w) and different concentrations of a commercial n…
Preparation of silicon-organic films for LC alignment is described. Effect of the molecular structure of organic substituents in siloxane chains on type of LC the alignment (homeotropic, tilted, planar) is considered. Contribution of polar and dispersion parts of the surface energy of siloxane films is discussed.
Using the continuum theory the influence of the external magnetic field on the ferrocholesteric — ferronematic phase transition is analyzed. The field being applied normal to the helix. Soft homeotropic coupling between the magnetic particles and the cholesteric molecules is assumed. The diamagnetic anisotropy of the…
The method presented in this paper pertains to an optical roughness meter that considers a fabric in all surface directions. A previous paper presented a tribological method for investigating textile fabrics, which used a roughness meter with a contact between the probe and the surface. However, a contact is not alway…
Anisotropy induction in the azo-polymer introduced into microporous glass under irradiation with polarised UV light is investigated. Practically pure “angular hole burning” mechanism is realised. Influence of the porous matrix on the life-time of cis-isomers, dipol-dipol interaction of polymer side chains, main-chain…
Thermoluminescence (TL) and thermally stimulated exoelectron emission (TSEE) in calcium phosphate doped with rare earth ions, such as Dy or Tm, have been studied, because its effective atomic number is close to that of human bones and teeth. It is found that Ca3(PO4)2 doped activators show the TL and TSEE sensitivity…
tert -Butylcatechol (TBC) is an efficient inhibitor of parasitic polymerization of many monomers during their transportation and storage. Just before the monomers are used, removal of the inhibitor is often necessary and can easily be achieved by adsorption on alumina. The influence of the main physical parameters of…
New liquid crystalline materials of the general formula have been synthesized (R1, R2 are alkyl chains). Mesomorphic properties were determined using polarizing microscopy. All compounds showed very broad smectic C* phase (about 70–90 K) and the cholesteric phase. No smectic A phase was observed. In the smectic C* pha…
Treatment of [Fe(OEP)]2O with trichloroacetic acid (2.5-fold excess) results in the formation of (octaethylporphinato)(trichloroacetato)iron(III). Various crystalline solvates can be isolated, depending on the crystallization solvent. Initial crystallization with CHCl3/hexanes resulted in the isolation of a monoclinic…
Five new polyamideimides (PAI) were synthesized from five diacid chlorides with preformed imide rings and a telechelic α,ω-diamino-polyoxyethylene (Jeffamine JFA ED600). The diacid chloride monomers could be obtained in high yields (77–92%) from chlorinating the corresponding diacids which were obtained from the react…
The synthesis and properties of a new mesogenic/nonmesogenic copolymer system, namely the poly[6-(4′-methoxyazobenzene-4′-oxy)hexyl methacrylate]-co-poly[methyl methacrylate]s, are described. Copolymers containing 0.59 or greater mol fraction of the mesogenic side-groups exhibit nematic behaviour while those containin…