Materials Literature
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Anionic polymerization of isoprene initiated by an alkyl lithium containing a silyl ether protected hydroxyl functionality followed by termination with ethylene oxide gave α,ω-functionalized polyisoprene with narrow molecular weight distribution and prescribed molecular weight in high yield. Deprotection resulted in α…
A series of poly(butylene terephthalate- co -butylene 2,6-naphthalate) (P(BT- co -BN)) random copolymers were synthesized, and their cocrystallization behavior was investigated by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). The P(BT- co -BN) copolymers, which are found to be statis…
The enzymatic ring-opening polymerization of 6-membered cyclic depsipeptides, 3(S)-isopropyl-morpholine-2,5-dione, 3(R)-isopropyl-morpholine-2,5-dione, 3(R,S)-isopropyl-morpholine-2,5-dione, (3S, 6R,S)-3-isopropyl-6-methyl-morpholine-2,5-dione, 3(S)-isobutyl-morpholine-2,5-dione, 3(S)-sec-butyl-morpholine-2,5-dione, 6…
Abstract The crystal structure of synthetic ‘plumbonacrite’, Pb 5 O(OH) 2 (CO 3 ) 3 , hexagonal, P6 3 cm , a = 9.0921(7), c = 24.923(3)Å, V = 1784.3(3)Å 3 , Z = 6, has been solved by direct methods and refined to R = 0.049. There are six symmetrically independent Pb 2+ positions in the structure, the coordination poly…
Surface-enhanced Raman spectroscopy (SERS) is used to detect catecholamines—viz., dopamine, norepinephrine, epinine, and isoproterenol—using a new substrate prepared with sol-gel technology. Catecholamines are complexed at the surface by iron(III) ions, which were introduced during the reduction of the silver ions emb…
Abstract Non-substituted 1,2-bis(3-thienyl)perfluorocyclopentene 1a was synthesized and its photochromic reactivity was compared with 1,2-bis(2,5-dimethyl-3-thienyl)perfluorocyclopentene 4a. Upon irradiation with ultraviolet light 1a easily decomposed and two kinds of by-products were produced in addition to the norma…
The structures of three R(6) human insulin hexamers have been determined. Crystals of monoclinic m-cresol-insulin, monoclinic resorcinol-insulin and rhombohedral m-cresol-insulin diffracted to 1. 9, 1.9 and 1.78 A, respectively, and have been refined to residuals of 0.195, 0.179 and 0.200, respectively. In all three s…
The stationary and time-resolved photoluminescence spectra of n -pentyl- n ′-cyanobiphenyl (5CB) are studied in a mesophase and solid-crystal state. The photoluminescence spectra of 5CB are determined by the molecular configuration and the intramolecular charge transfer in the excited state. It is shown that in the me…
This investigation aimed to determine the in plant feasibility of decreasing, to an amount close to the minimum literature value, the calcium addition to liquid steel for prevention of alumina buildup during continuous casting. Six plant trials were carried out at calcium additions of 0·14 kg/t of steel (reduced from…
Elastic properties of the perovskite manganite ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{MnO}}_{3}(x=0.12,0.165,0.3)$ with both orbital and charge degrees of freedom have been investigated by means of ultrasonic measurements. Above the structural phase transition point ${T}_{s}=290\mathrm{K}$ for $x=0…
Study of an α-Al2O3 single crystal by electron-induced x-ray emission spectroscopy and cathodoluminescence is reported. The relative intensities of optical emissions due to F+ and F centers have been determined as a function of the parameters of the electron beam and the annealing of the sample. It is shown that the F…
Abstract A hydrothermally altered rhyolitic hyaloclastite from Ponza island, Italy, has four alteration zones with unique clay assemblages: (1) a non-pervasive argillic zone characterized by smectite; (2) a propylitic zone with interstratified illite-smectite (I-S) containing 10–85% illite (I); (3) a silicic zone comp…
The crystal transformation in lamellar crystals of polybutene-1 grown from an amyl acetate solution was studied by cryogenic high-resolution transmission electron microscopy. The shape of the transformed trigonal (form-1) crystal domains in the surrounding tetragonal (form-2) crystal was successfully revealed. Along w…
The photodegradation of a variety of donor–acceptor-substituted azobenzene nonlinear optical chromophores has been studied. The variables examined that influence the rate of degradation include chromophore and host polymer structure, irradiation wavelength, temperature, and atmosphere.
Segmented polyurethanes based on diphenylmethane-4,4′-diisocyanate and polytetra-methylene glycol were synthesized using a mixture of polyhedral oligomeric silsesquioxane (POSS)-diol and 1,4-butanediol as chain extenders. The polymers were characterized by differential scanning calorimetry, wide-angle x-ray diffractio…
In this article we report on the thermal properties of the ternary carbide Nb2SnC. Its heat capacity, cp, is 75 J/mol K at ambient temperatures and increases to ≈115 J/mol K at 1300 K. Analysis of cp measurements in the 4–15 K temperature range yields a Debye temperature of 324 K and a density of states at the Fermi l…
The results of electrical and dielectric studies in semicrystalline nylon 11 (degree of crystallinity 62%) by means of dielectric relaxation spectroscopy (DRS) in the frequency range 10−2–106 Hz at temperatures between the glass transition temperature of about 40 °C and the melting temperature of about 190 °C are repo…
Kinetics of the polymerisation of ε-caprolactone and L,L-dilactide initiated with tin(II) 2-ethylhexanoate (tin octoate (Sn(Oct)2)) and carried out in the presence of 2,6-di-tert-butylpyridine (1) and/or 1,8-bis(dimethylamino)naphthalene (2), in THF as the solvent, at 80°C was studied. The rate of polymerisation of th…
The thermally induced amorphous-to-crystalline transition has been studied for bulk sheets and micrometre-sized particles of magnesium silicate glass (MgSiO3), nanometresized amorphous magnesium silicate (MgSiO3 and Mg2SiO4 smokes) and amorphous silica particles (SiO2). Silicate glass was produced by the shock-quenchi…
High-resolution and magnetic neutron-diffraction measurements were performed to investigate the crystal and magnetic structures of bilayered FeOCl and polyaniline-intercalated FeOCl. A quasi-two-dimensional crystallographic structure, where charge neutral $({\mathrm{Fe}}_{2}{\mathrm{O}}_{2}{\mathrm{Cl}}_{2}{)}_{n}$ la…