Materials Literature
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Polymerization of two isomeric heterocyclic monomers, 3-methyl-1-vinylpyrazole and 1-allylimidazole, was investigated under pulsed plasma conditions. Large-scale, progressive variations in polymer compositions were observed with sequential changes in the plasma duty cycles employed, all other plasma variables being he…
Pyruvate kinase from rabbit muscle has been cocrystallized as a complex with MgIIATP, oxalate, Mg2+, and either K+ or Na+. Crystals with either Na+ or K+ belong to the space group P2(1)2(1)2(1), and the asymmetric units contain two tetramers. The structures were solved by molecular replacement and refined to 2.1 (K+)…
Potential holographic materials are obtained from the azobenzene-functionalized dendrimers described herein (shown schematically on the right). Even in the largest species presented, which contains up to 32 azobenzene chromophores, each chromophoric unit behaves independently compared to “monomer” model compounds. Dif…
Three neutral π-associated [2]catenanes have been synthesised from the oxidative dimerisation of terminal acetylene-equipped electron-deficient diimides in the presence of an electron-rich dinaptho-crown template (below). The mutual recognition of the complementary donor–acceptor building blocks is revealed in solid-s…
We model an apparent instability seen in recent experiments on current induced step bunching on Si(111) surfaces using a generalized 2D BCF model, where adatoms have a diffusion bias parallel to the step edges and there is an attachment barrier at the step edge. We find a new linear instability with novel step pattern…
A ferromagnetically coupled gadolinium–radical compound is described. A series of three lanthanide complexes of general formula [Ln(organic radical)2(NO3)3] (Ln =Y3+, La3+, and Gd3+, shown on the right) have been synthesized. With the paramagnetic GdIII a ferromagnetic interaction with the ligands was found, which giv…
The authors analyze the effects of electrodynamic retardation on the collective modes in an unmagnetized infinite superlattice modeled as an array of parallel two-dimensional plasma layers embedded in a dielectric substrate. The present work concentrates for the most part on correlated semiconductor superlattices, alt…
Glass ceramics containing micrometer-sized lead zirconate titanate have been synthesized and nanometer-sized lead sulphide (PbS) phase has been grown within these by treatment in hydrogen sulphide gas. The PbS particle sizes vary from 4.4 to 15.3 nm. Dielectric measurements on the nanocomposites have been carried out…
The asymmetric unit of the title complex, [SbPc]I (Pc = C32H16N8), consists of an [SbPc]+ cation and an I− anion. A combination of ionic and acceptor–donor interactions links the [SbPc]I moieties to form pseudo dimers in the unit cell. The pseudo dimers are linked through I⋯H—Cbenzole hydrogen-bonded interactions to f…
Observation has been made of a photonic enhancement effect during optical rapid thermal annealing (RTA) of high dose, As implants in Si. Arsenic implant activation using optical radiation heating from tungsten–halogen lamps, λpeak=0.8 μm, was compared with annealing in a continuously heated rapid thermal vertical furn…
Perylenetetracarboxydiimide (PEDI) molecularly dispersed in polyamic acid (PAA) and polyimide (PI) films has unique fluorescence properties. An originally strong fluorescence of PEDI is efficiently quenched in the PAA films. The systematic variation of the chain structure of the PAA matrices revealed that the aromatic…
The relaxation behavior of four amorphous poly(aryl ether ketone)s was investigated using dielectric relaxation spectroscopy and dynamic mechanical analysis. The temperature dependence of the relaxation times of the glass transition process and the cooperative nature of this process were unaffected by changes in polym…
The pressure–volume–temperature (PVT) properties of three commercial samples of poly(dimethylsiloxane) are studied experimentally and theoretically in the temperature range 25–150°C and for pressure to ∼ 3 kbar. The Tait equation is employed to represent the data at elevated pressure. Isothermal compressibilities are…
Laser selective excitation, excited state absorption, two-photon absorption, and fluorescence line narrowing techniques have been used to investigate the electronic energy level structure of the Cm3+ ion diluted in the host crystal Cs2NaYCl6. In this crystal the Cm3+ ion replaces a Y3+ ion at an octahedral site (Oh sy…
We report on magnetic measurements and electronic structure investigations of the alloyed compounds Zr-Ni-Sn and Ti-Ni-Sn. Both belong to the group of semi-Heusler alloys, and are classified as narrow-gap semiconductors with indirect gaps near 500 meV. Tetravalent ions (Zr,Ti) are partly replaced by Ce, with a Ce conc…
The effects of the inclusion of manganese in small ZnS nanocrystals are investigated. Our calculation is based on a tight-binding model with renormalized parameters similar to those of the defect-molecule approach for substitutional transition-metal ions in semiconductors. The nanocrystals of Mn-doped ZnS were 1.1--3.…
Peroxide induced crosslinking and degradation of polyvinyl chloride (PVC) were experimentally investigated using an on-line electron spin resonance (ESR) spectroscopy technique. The reaction variables included temperature, peroxide type and concentration. A single line ESR spectrum was observed with its peak-to-peak w…
Transport data for paratoluene sulfonate dope polypyrrole films in the insulating regime and near the metal-insulator (M-I) boundary are presented and analyzed. Samples in the insulating region show a crossover from Mott to Efros–Shklovskii variable range hopping conduction at T=5 K and magnetoconductance of these sam…
Degradation of poly(methyl methacrylate) (PMMA) thin films by vacuum ultraviolet (VUV) monochromatic synchrotron radiation was investigated by ultraviolet photoelectron spectroscopy. The photodegradation reaction was analyzed, for the first time, by different spectrometry techniques and ab initio molecular orbital cal…
A beam of light incident upon a diffractive structure can under resonance conditions be subject to a rather large lateral displacement. The effect is demonstrated with a Gaussian profile beam and two geometries based on a waveguide grating and a single-mode waveguide.