Synthesis and characterization of polyaryleneetherketone triphenylphosphine oxides incorporating cycloaliphatic/cage hydrocarbon structural units

New high temperature polyaryleneetherketone triphenylphosphine oxides incorporating trans‐1,4‐cyclohexane, 1,3‐adamantane, and 4,9‐diamantane structural units were synthesized by the base‐promoted polymerization reaction between 4,4′‐difluorotriphenylphosphine oxide and the novel dihydroxy monomers trans‐1,4‐bis(4‐hydroxybenzoyl)cyclohexane, 1,3‐bis(4‐hydroxybenzoyl)adamantane, and 4,9‐bis(4‐hydroxybenzoyl)diamantane. The monomers were synthesized in a good yield by a two‐step procedure involving the Friedel–Crafts acylation of anisole by the diacid chlorides trans‐1,4‐cyclohexanedicarbonyl chloride, 1,3‐adamantanedicarbonyl chloride, and 4,9‐diamantanedicarbonyl chloride, followed by demethylation with pyridine hydrochloride. The polymers, which could be processed into tough, free standing films from organic solvents, exhibited high T_g's in the range of 192–239° as well as thermooxidative stabilities (5% weight loss in air) in the range of 445–490°. Preliminary results from a UV–visible spectroscopic study of dilute solutions of the polymers in chloroform showed absorption maxima in the 263–274 nm region and transparency to spectral radiation in the 300–800 nm range, indicating that these triphenylphosphine oxide polymers could have potential applications for space thermal control coatings. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6134–6142, 2004     

Strong tie between cut-wire pair and continuous wire in combined-structure metamaterials

A detail study on the continuity between cut-wire pair and continuous wire in combined-structure metamaterials operating at the microwave frequency regime is reported. By using numerical simulations and microwave experiments, we investigated the effect of the width and position of the continuous wire relative to the cut-wire pair on the electromagnetic response of a combined structure. It was found that these parameters play an important role in determining whether the left-handed (LH) behavior is obtained or not. In addition, we also studied the influence of lattice constant on the LH behavior of combined structure. Our results showed that the LH behavior is strongly dependent on the lattice constant in the E direction. However, it remains unchanged according to the lattice constant in the H direction. A good coincidence between the measurements and the numerical simulations was shown. It is expected that this work will allow us to optimize the appropriate characteristic parameters even without avoiding the trial-and-error fabrications.     

Antioxidative and α-glucosidase inhibitory constituents of Polyscias guilfoylei: experimental and computational assessments

Molecular Diversity - Searching for bioactive agents from medicinal plants, eleven constituents were isolated from Polyscias guilfoylei stem for the first time, including a nucleoside uracil (1),...     

1-Acyloxygermatranes

A one-step method for the synthesis of 1-acyloxygermatranes RC(O)OGe(OCH₂CH₂)₃N in the reaction of germanium dioxide with triethanolamine and a carboxylic acid was developed. 1-Acyloxygermatranes, including those containing biologically active acyloxy groups (R = 2-MeC₆H₄CH₂OCH₂, C₆H₅, 2-HOC₆H₄), were obtained with a 82–96.5% yield.     

Novel Hybrid Methods for Pseudomonotone Equilibrium Problems and Common Fixed Point Problems

The purpose of this article is to introduce some hybrid algorithms for finding a common element of the solution sets of pseudomonotone equilibrium problems and the fixed point sets of nonexpansive mappings in real Hilbert spaces. Our algorithms combine Mann’s iterative methods and Armijo line-search with parallel splitting-up and hybrid techniques. The strong convergence of the proposed algorithms are established without the assumption on the Lipschitz-type condition for the bifunctions involved.     

Synthesis and structural characterization of uranium-doped Ca<Subscript>2</Subscript>CuO<Subscript>3</Subscript>, a one-dimensional quantum antiferromagnet

The technological settings of a modified sol-gel method for the preparation of highly fine homogeneous powder of Ca₂CuO₃ doped with uranium 238 (x= 0.0–0.05) is presented. The analysis of structure, purity of phases and the justification for the role of uranium in the given compounds are provided, together with an almost complete classification of the observed optical phonons by means of Raman, IR measurements and ab initio calculations. A significant reduction in particle size was achieved by doping, and a strong correlation between resistivity and doping concentration was observed and explained using the phonon-assisted electron hopping conduction model. The persistence of a covalent insulation state in all compounds is an interesting feature of this doping.