Mesoscopic simulation of metastable microphases in the order–order transition from gyroid-to-lamellar states of PS–PI diblock copolymer

The formation of metastable microphases during the order–order transition (OOT) from gyroid-to-lamellar states of a poly(styrene)–poly(isoprene) (PS–PI) copolymer has been investigated on a mesoscopic level using dissipative particle dynamics simulations. The formation of the gyroid microphase was obtained via an order–disorder transition process (ODT). The microphase was then subjected to thermal heating cycles. A thermodynamic instability of poly(styrene) microdomains due to temperature effects induces anisotropic composition fluctuations in the gyroid structure and a microphase transformation from gyroid-to-lamellar takes place via an OOT. Two metastable microphases (hexagonal perforated layers and cylinders) were detected during the thermal process. Results are consistent with experimental and theoretical studies.     

Study of the charge displacement at constant potential during CO adsorption on Pt(110) and Pt(111) electrodes in contact with a perchloric acid solution

A new electrochemical approach has been made, employing the current—time transient responses when a CO adlayer is formed at a platinum electrode at various controlled potentials where CO oxidation does not take place. The case of Pt(110) is compared with those of Pt(111) and Pt(111) disordered after ten cycles of oxygen adsorption—desorption. In order to avoid interference with anion-specific adsorption, the study was carried out in a perchloric acid solution. There is good agreement between the charge measured by voltammetry in the absence of CO and the charges measured during the current—time transients. This is indicative that the latter charges are produced by the displacement of the species at the interface as a result of CO adlayer formations. The sign of the current transient has been found to depend on the potential at which CO adsorption is carried out. This dependence may be related to the nature of species which are present in the interfacial region, providing new complementary information that voltammetry cannot yield.     

Monotone insertion of lattice-valued functions

Insertion of lattice-valued functions in a monotone manner is investigated. For L a ⊲-separable completely distributive lattice (i.e. L admits a countable base which is free of supercompact elements), a monotone version of the Katětov-Tong insertion theorem for L-valued functions is established. We also provide a monotone lattice-valued version of Urysohn’s lemma. Both results yield new characterizations of monotonically normal spaces. Moreover, extension of lattice-valued functions under additional assumptions is shown to characterize also monotone normality. This research was supported by the MEyC and FEDER under grant MTM2006-14925-C02-02/ and by UPV05/101     

Polarographic study of a benzodiazepinooxazole: Oxazolam

Summary The polarographic behaviour of 10-chloro-2,3, 7,11b-tetrahydro-2-methyl-11b-phenyloxazolo-[3,2-d][1,4]-benzodiazepin-6(5H)-one (Oxazolam) was studied in the pH range 1–12. The reduction processes of Oxazolam and its hydrolysis product are irreversible and their currents are predominantly diffusion-controlled. The linear relationship between current and Oxazolam concentration in sulphuric acid medium permits its polarographic determination up to 6.08×10^–5 mol/l. The detection limit was 1.52×10^–7 mol/l (50 ppb). The reproducibility of the method in terms of relative standard deviation was 1.74% and 1.85% for ten determinations at 1.48×10^–5 mol/l and 1.37×10^–6 mol/l levels, respectively. The method developed was applied to the determination of the compound in its formulations, Hializan-10 mg, obtaining errors lower than 2%.

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Polarographische Untersuchung eines Benzodiazepinoxazols: Oxazolam

     

The protonation constant of triethanolamine in KBr and KNO3 solutions at 25°C

We determined the stoichiometric acid-base constants of triethanolamine at 25°C in KBr and KNO₃ at different ionic strengths by the potentiometric technique using glass electrodes sensitive to the H⁺ ion. By applying the Pitzer equations for the activity coefficients of the species present in the medium we obtained equations accounting for the dependency of pK on the ionic strength. The coefficients thus obtained are critically analyzed.     

Waveguides and gratings fabrication in zirconium-based organic/inorganic hybrids

Sol–gel derived poly(oxyethylene)/siloxane organic/inorganic di-ureasil hybrids containing different amounts of methacrylic acid (McOH, CH₂=C(CH₃)COOH)) modified zirconium oxo-clusters (Zr-OMc) were processed as thin films deposited in glassy substrates via spin coating and as transparent and shape controlled monoliths. Channel monomode waveguides and diffraction gratings were UV patterned using the Talbot interferometer and the Lloyd mirror interferometer experimental setups. The time dependence of the diffraction gratings efficiency was studied for hybrids containing different amounts of Zr-OMc. Finally, the number of propagating modes and the refractive index gradient within the waveguide region, determined as a Gaussian section located below the patterned channel, was evaluated and modeled, a maximum index contrast of 2.43 × 10^?5 being estimated.     

Reaction of schiff bases with acrylamides. Synthesis of 2-oxotetrahydropyridines

Ketimines react with acrylamide and methacrylamide in the presence of aluminium chloride to afford 2-oxotetrahydropyridines by a C-alkylation pathway.     

Prevision des spectres de résonance magnétique nucléaire de 13C par intelligence artificielle: le problème de la codificationPrediction of 13C-nuclear magnetic resonance spectra by artificial intelligence: the problem of coding structures

Possible errors in earlier methods of coding structures are discussed, particularly with regard to α- and β-conformation and double bonds. The proposed method of coding is based on the absolute interatomic distances and the relative orientations of atoms. The coding system agrees with previous theoretical equations, except for density matrices; the usual classification of α, β and δ effects is obviously not included. An advantage of the method is that neighbouring atoms which have negligible effect are not included in the coding, so that the number of plausible structures is reduced. Another advantage is that similar structures can be tested, atom by atom, to a level at which complete structural equivalence no longer exists. The program developed on this basis is applicable with personal computers and provides options which enable the theoretical spectrum to be predicted, the signals to be interpreted if the experimental spectrum is known, and the influence of each neighbouring atom on the carbon signal to be studied.