A new route to triphenylpyridines utilizing ketoximes as building blocks via cascade reactions under iron‐organic framework catalysis

Iron‐based metal–organic framework VNU‐20 was utilized as a heterogeneous catalyst for cascade reactions between ketoximes and dibenzyl ether to produce 2,4,6‐triphenylpyridines. Additionally, benzyl alcohol and (dimethoxymethyl)benzene could be used as an alternative starting materials for the transformation. The oxidant exhibited a remarkable impact on the reactions, and di‐tert‐butylperoxide was the most appropriate candidate. The VNU‐20 displayed higher efficiency than many homogeneous and heterogeneous catalysts. The catalyst was reusable for the cascade reactions without a noticeable deterioration in catalytic activity. This transformation is new, and would offer alternative routes to triphenylpyridines utilizing ketoximes as building blocks.     

A numerical evaluation of very oscillatory infinite integrals by asymptotics

Recently, Levin and Sidi have given some nonlinear methods for the accurate evaluation of slowly converging infinite integrals. But, one needs to solve some very instable linear systems, when, for example, the integrand have an increasingly rapid oscillatory behavior at infinity. In this work, we present a direct method, which avoids the instable linear systems.     

Radiation-resistant polypropylene improved by a compatibilizer

A compatibilizer is normally added to enhance the compatibility during blending of two polymers. Polypropylene (PP) has two degradations, during irradiation and also during storage after irradiation in radiation sterilization. A compatibilizer was added to PP to reduce these degradations. Compatibilizers, such as hydrogenated styrene (10 mol%)/butadiene rubber (CPB-2) and ethylene/propylene rubber grafted with maleic anhydride, were found to retard remarkably the above-mentioned degradations of PP. The compatibilizer concentration required for enhancing the radiation resistance of PP depends on the radiation resistance before addition of the compatibilizer. Poor radiation-resistant PP of a lower molecular weight (Melt flow index, 10) required a higher concentration, above 10% of CPB-2 to impart radiation resistance, but high-molecular-weight PP (Melt flow index, 1.0) and copolypropylene (CPP) with an ethylene content of 2.5% required CPB-2 of 5% and 10% to induce sufficient radiation resistance. Furthermore, CPB-2 was effective for improvement of transparency besides its contribution to radiation resistance of PP. The CPB-2 lead to lower crystallinity to retard the crystallization of PP and CPP and also may result in a mixed monoclinic and smectic structure giving radiation resistance.     

Dosage de l'or spectrophotométrie d'absorption atomique sans flamme: Application aux minerais de zinc,de plomb et à leurs sous-produits

The application of flameless atomic absorption spectrometry to the determination of gold in raw sulfide ores of zinc and lead is described. After dissolution of the sample by a mixture of hydrochloric and nitric acids and bromine, gold is extracted by MIBK and the extract is submitted to atomization. The detection limit is estimated as 0.003 p.p.m. and the reproducibility as 4–5 % at the 2 p.p.m. level.     

A sufficient condition for a set of calibrated surfaces to be area-minimizing under diffeomorphisms

We extend Choe’s idea in [1] to nonpolyhedral calibrated surfaces and give some examples of polyhedral sets over right prisms and nonpolyhedral calibrated surfaces. Received: 4 October 2004     

A molecular docking simulation study on potent inhibitors against Rhizoctonia solani and Magnaporthe oryzae in rice: silver-tetrylene and bis-silver-tetrylene complexes vs. validamycin and tricyclazole pesticides

Structural Chemistry - Rice, well known as the most important staple food source worldwide, is highly susceptible to many infectious diseases, especially rice sheath blight caused by fungus...     

Binary and ternary alkali polyphosphates (MPO3, M = Li,Na, K) for thermal energy storage

Journal of Thermal Analysis and Calorimetry - Up-to-date, solar salt (a mixture of 60 mass% NaNO3 and 40 mass% KNO3) is practically the only media for thermal energy storage (TES) in concentrated...     

Two new noncentrosymmetric (NCS) polar oxides: syntheses, characterization, and structure-property relationships in BaMTe2O7 (M = Mg2+ or Zn2+)

Two new noncentrosymmetric (NCS) polar oxides, BaMgTe(2)O(7) and BaZnTe(2)O(7), have been synthesized and characterized, with their crystal structures determined by single crystal X-ray diffraction. The iso-structural materials exhibit structures consisting of layers of corner-shared MgO(5) or ZnO(5), Te(6+)O(6), and Te(4+)O(4) polyhedra that are separated by Ba(2+) cations. The Te(4+) cation is found in a highly asymmetric and polar coordination environment attributable to its stereoactive lone-pair. The alignment of the individual TeO(4) polar polyhedra results in macroscopic polarity for BaMgTe(2)O(7) and BaZnTe(2)O(7). Powder second-harmonic generation (SHG) measurements revealed a moderate SHG efficiency of approximately 5 × KDP (or 200 × α-SiO(2)) for both materials. Piezoelectric charge constants of 70 and 57 pm/V, and pyroelectric coefficients of -18 and -10 μC·m(-2)·K(-1) were obtained for BaMgTe(2)O(7) and BaZnTe(2)O(7), respectively. Although the materials are polar, frequency dependent polarization measurements indicated that the materials are not ferroelectric, that is, the observed macroscopic polarization cannot be reversed. Infrared, UV-vis diffuse spectroscopy, and thermal properties were also measured. Crystal data: BaMgTe(2)O(7), orthorhombic, space group Ama2 (No. 40), a = 5.558(2) ?, b = 15.215(6) ?, c = 7.307(3) ?, V = 617.9(4) ?(3), and Z = 4; BaZnTe(2)O(7), orthorhombic, space group Ama2 (No. 40), a = 5.5498(4) ?, b = 15.3161(11) ?, c = 7.3098(5) ?, V = 621.34(8) ?(3), and Z = 4.     

Newton-like methods for efficient solutions in vector optimization

In this work we study the Newton-like methods for finding efficient solutions of the vector optimization problem for a map from a finite dimensional Hilbert space X to a Banach space Y, with respect to the partial order induced by a closed, convex and pointed cone C with a nonempty interior. We present both exact and inexact versions, in which the subproblems are solved approximately, within a tolerance. Furthermore, we prove that under reasonable hypotheses, the sequence generated by our method converges to an efficient solution of this problem.     

Derivatives of the Efficient Point Multifunction in Parametric Vector Optimization Problems

In this paper, we deal with the sensitivity analysis in vector optimization. More specifically, formulae for inner and outer evaluating the S-derivative of the efficient point multifunction in parametric vector optimization problems are established. These estimating formulae are presented via the set of efficient/weakly efficient points of the S-derivative of the original multifunction, a composite multifunction of the objective function and the constraint mapping. The elaboration of the formulae in vector optimization problems, having multifunction constraints and semiinfinite constraints, is also undertaken. Furthermore, examples are provided for analyzing and illustrating the obtained results.