Symmetric Intersections of Rauzy Fractals

In this article we study symmetric subsets of Rauzy fractals of unimodular irreducible Pisot substitutions. The symmetry considered is reflection through the origin. Given an unimodular irreducible Pisot substitution, we consider the intersection of its Rauzy fractal with the Rauzy fractal of the reverse substitution. This set is symmetric and it is obtained by the balanced pair algorithm associated with both substitutions.     

Development of dynamic headspace-liquid phase microextraction method performed in a home-made extraction vessel for extraction and preconcentration of 1,4-dioxane from shampoo

In the present study, a new, simple, rapid, and environmentally friendly headspace-liquid phase microextraction method followed by gas chromatography–flame ionization detection has been developed for the extraction/preconcentration and determination of 1,4-dioxane from shampoo. The developed procedure is performed in a home-made extraction vessel, connected to a glass vial containing sample and extraction solvent. In this method, an aliquot weight of shampoo is mixed with a binary mixture of n-hexane and dichloromethane (50:50, v/v) as the extractant and the target analyte is extracted during a liquid–liquid extraction procedure. Then a home-made extraction vessel containing a few microliters of a collection/extraction solvent is contacted to a glass vial containing the organic phase obtained from the previous step. By heating 1,4-dioxane is vaporized and enriched in a μL volume of the collection/extraction solvent. Then an aliquot volume of the collected phase is injected into the separation system. The effect of several factors which may influence performance of the method, including kind and volume of the extraction solvents used in both steps, extraction temperature, extraction time, and salt addition were evaluated. Under the optimum extraction conditions, limits of detection and quantification for the target analyte were obtained 0.52 and 1.73 μg kg^?1, respectively. Enrichment factor and extraction recovery were 333 and 89 %, respectively. The method precision was evaluated at a concentration of 25 μg kg^?1 and relative standard deviation was less than 6.9 % for intra-day (n = 6) and inter-day (n = 4) precisions. Finally, the proposed method has been successfully applied in analysis of 1,4-dioxane in different shampoo samples.     

Synthesis,Reactions, and Pharmacological Activities of Some Pyrimidines Using (<Emphasis Type="Italic">N</Emphasis>-Methylindolyl)acetic Acid as Synthon

Summary. A series of pyrimidinones, thienopyrimidines, and their derivatives were synthesized using N-methylindolyl acetic acid as a starting material. Sixteen new heterocyclics containing a pyrimidine ring were thus prepared. The pharmacological screening showed that many of these compounds have good analgesic and antiparkinsonian activities comparable to Voltarene^? and Benzatropine^? as reference drugs. The structure assignments of the new compounds based on chemical and spectroscopic evidence. The detailed synthesis, spectroscopic data, and pharmacological properties are reported.     

Simple and indecomposable twofold cyclic triple systems from Skolem sequences

We construct simple indecomposable twofold cyclic triple systems TS₂(v) for all v ≡ 0, 1, 3, 4, 7, and 9(mod 12), where v = 4 or v ≥ 12, using Skolem‐type sequences. © 2000 John Wiley & Sons, Inc. J Combin Designs 8: 402–410, 2000     

Diffusive-dispersive traveling waves and kinetic relations III. An hyperbolic model of elastodynamics

This is the third part of a series devoted to the existence, uniqueness, monotonicity, and asymptotic properties of the traveling wave solutions of diffusive-dispersive conservation law. In this part, we focus attention on a nonconvex hyperbolic model of two conservation laws arising in nonlinear elastodynamics and including nonlinear viscosity and capillarity terms. On one hand, using the techniques developed earlier, we study the properties of the corresponding classical and nonclassical shock waves and their corresponding kinetic relation. Several new features are found for this (hyperbolic) model: First of all, we distinguish here between a kinetic function and an inverse kinetic function; the latter is always globally defined but may fail to be globally invertible. Second, we show that shock waves with sufficiently small amplitude are always classical, for a fixed ratio of diffusion and dispersion. Third, we determine here the asymptotic behavior of the kinetic function for both shocks with large and small amplitudes.

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Sunto  Questa è la terza parte di una serie di lavori dedicati all'esistenza, unicità, monotonia e proprietà asintotiche delle soluzioni d'onda di propagazione per leggi di conservazione diffusive-dispersive. In questa parte, l'attenzione è focalizzata su un modello iperbolico non convesso di due leggi di conservazione che sorgono in elastodinamica non lineare, che tengono conto della viscosità non lineare e dei termini di capillarità. Da una parte, utilizzando le tecniche precedentemente sviluppate, studiamo le proprietà delle corrispondenti onde d'urto classiche e non classiche e le loro corrispondenti relazioni cinetiche. Diverse nuove proprietà sono state trovate per questo modello (iperbolico). Innanzitutto, qui distinguiamo tra una funzione cinetica ed una funzione cinetica inversa, quest'ultima essendo sempre definita globalmente ma possibilimente non sempre globalmente iinvertibile. In secondo luogo, mostriamo che onde d'urto con ampiezza sufficientemente piccola sono sempre classiche, per un valore fissato del rapporto tra diffusione e dispersione. In ultimo, determiniamo il comportamento asintotico della funzione cinetica per onde d'urto aventi sia ampiezza grande sia piccola.

     

Synthesis and Computational Characterization of Organic UV-Dyes for Cosensitization of Transparent Dye-Sensitized Solar Cells

The fabrication of colorless and see-through dye-sensitized solar cells (DSCs) requires the photosensitizers to have little or no absorption in the visible light region of the solar spectrum. However, a trade-off between transparency and power conversion efficiency (PCE) has to be tackled, since most transparent DSCs are showing low PCE when compared to colorful and opaque DSCs. One strategy to increase PCE is applying two cosensitizers with selective conversion of the UV and NIR radiation, therefore, the non-visible part only is absorbed. In this study, we report synthesis of novel five UV-selective absorbers, based on diimide and Schiff bases incorporating carboxyl and pyridyl anchoring groups. A systematic computational investigation using density functional theory (DFT) and time-dependent DFT approaches was employed to evaluate their prospect of application in transparent DSCs. Experimental UV/Vis absorption spectra showed that all dyes exhibit an absorption band covering the mid/near-UV region of solar spectrum, with a bathochromic shift and a hyperchromic shifts for Py-1 dye. Computational results showed that the studied dyes satisfied the basic photophysical and energetics requirements of operating DSC as well as the stability and thermodynamical spontaneity of adsorption onto surface of TiO₂. However, results revealed outperformance of the thienothiophene core-containing Py-1 UV-dye, owing to its advantageous structural attributes, improved conjugation, intense emission, large Stokes shift and maximum charge transferred to the anchor. Chemical compatibility of Py-1 dye was then theoretically investigated as a potential cosensitizer of a reference VG20-C2 NIR-dye. By the judicious selection of pyridyl anchor-based UV-absorber (Py-1) and carboxyl anchor-based NIR-absorber (VG20), the advantage of the optical complementarity and selectivity of different TiO₂-adsorption-site (Lewis- and Bronsted-acidic) can be achieved. An improved overall PCE is estimated accordingly.     

Existence of directed GDDs with block size five

In this article, we construct directed group divisible designs (DGDDs) with block size five, group-type hⁿ, and index unity. The necessary conditions for the existence of such a DGDD are n ≥ 5, (n − 1)h ≡ 0 (mod 2) and n(n − 1)h² ≡ 0 (mod 10). It is shown that these necessary conditions are also sufficient, except possibly for n = 15 where h ≡ 1 or 5 (mod 6) and h ≢ 0 (mod 5), or (n, h) = (15, 9). © 1998 John Wiley & Sons, Inc. J Combin Designs 6: 389–402, 1998