Materials Literature
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Abstract Temperature dependence of radiation effect on various polymers including hydrocarbon and fluorocarbon polymers was investigated. Gas evolution and mechanical properties were measured in a wide range of temperatures. G‐values of chain scission and crosslinking were estimated. It has been made clear from those…
Covalent bonds between the heavy metal cations and the aluminosilicate framework have been discovered to be the cause of distinct structural characteristics in anhydrous sodalites Ag 6 [AlSiO 4 ] 6 and Tl 6 [AlSiO 4 ] 6 that differ significantly from their alkali metal containing analogues. Evidence of guest−framework…
The drawing behavior of the ultra-high molecular weight polyethylene (UHMW-PE) melts has been studied by comparing the stress/strain curves for two types of samples as polymerized using conventional Ziegler and newer metallocene catalyst systems. Two UHMW-PE samples, having the same viscosity average molecular weight…
Measurements of time-resolved photoluminescence reveal an F centre luminescence lifetime of 35 ms in Al2O3:C at room temperature, decreasing to less than 2 ms over the temperature range from 370 to 500 K. The decrease in the lifetime follows a classical Mott-Seitz dependence for thermal quenching of luminescence, with…
The effect of colloidal Au particle aggregation on surface-enhanced Raman scattering (SERS) spectra was probed by SERS filtration experiments. In this approach, SERS and optical spectra were recorded for trans-1,2-bis(4-pyridyl)ethylene (BPE)-aggregated solutions of colloidal Au filtered through straight-channel membr…
Poly(styrene- b -isobutylene- b -styrene) (PSt−PIB−PSt) triblock copolymers have been prepared for the first time via coupling of living PSt-PIB diblock copolymers in a one-pot procedure. The PSt−PIB diblock copolymer was synthesized by living sequential cationic polymerization in methylcyclohexane (MeChx)/methyl chlo…
Some metal containing block copolymers derived from polystyrene-block-poly(4-vinylpyridine) were synthesized. The complexation was achieved by reacting the poly(4-vinylpyridine) block with 2,2′-bipyridyl(tricarbonyl)rhenium(I) chloride in the presence of silver perchlorate. The resulting polymer metal complexes are ab…
The bis[4-(n-CmH2m+1O)-5-(p-C14H29C6H4N=N)]-substituted N,N′-salicylidenediamines H2[LN(m,14)] (N = 1: 1,2-diaminoethane; N = 2: 1,3-diaminopropane; N = 3: 1,3-diamino-2,2-dimethylpropane; m = 6 or 18) have been synthesized. Both the N = 2 and 3 series of compounds display a smectic C (SmC) mesophase, with clearing po…
The polyhydroxyalkanoic acid synthase gene from Chromobacterium violaceum (phaC(Cv)) was cloned and characterized. A 6.3-kb BamHI fragment was found to contain both phaC(Cv) and the polyhydroxyalkanoic acid (PHA)-specific 3-ketothiolase (phaA(Cv)). Escherichia coli strains harboring this fragment produced significant…
Structure and switching behavior were studied in liquid crystals consisting of bent-shaped molecules with the linkage of an alkylene spacer, m(O)AMnAM(O)m, where m and n are carbon numbers of end and spacer chains, respectively. All the compounds exhibit a fan-shaped texture without a fringe structure in their smectic…
The thermoelectric properties of superlattice thin films have been studied as functions of temperature. The superlattice thin films were prepared by the alternate deposition of Si and Ge heavily doped with Au in ultrahigh vacuum. They have an intended artificial interval, but each layer is in an amorphous state. An an…
The nature of surface hydroxyls present in the native air‐formed oxide film on titanium has been studied by X‐ray photoelectron spectroscopy (XPS), variable angle XPS, and secondary ion mass spectroscopy (SIMS). The surface isoelectric point of the oxide film on titanium is 5.0, as determined from XPS measurements; an…
The syntheses of a series of 1,3-dithiole-2-thione derivatives ( 3 − 6 ), bearing fused terthiophene or bis(2-thienyl)-2,5-furan units, are reported. These novel heterocycles are readily polymerized electrochemically to give stable electroactive materials. The target compounds were obtained in moderate to high yield v…
To overcome the difficulties of locating the molecular sites of general anesthetic action, we synthesized a novel photoactivable general anesthetic, 3-(2-hydroxyethyl)-3-n-pentyldiazirine (3-diazirinyloctanol), which anesthetized tadpoles with an ED(50) of 160 microM. Subanesthetic concentrations of 3-diazirinyloctano…
Two new series of achiral banana-shaped molecules have been prepared. Their mesomorphic, electrooptical and structural properties have been investigated. The first series of hydrogenated molecules shows the nematic phase with short chains (n=8–10), N and SmC phases with intermediate chain lengths (n = 11–13) and SmC p…
A new type of heterometallic silsesquioxane is reported in which Ln (Ln = Yb or Y) is coordinated to one (C6H11)7Si7O123- ligand and one (C6H11)7Si7O11(OSiMe3)2- ligand. Two Li atoms are incorporated into the structure, one bonded to two siloxy O atoms and the other to one siloxy O atom, one framework O atom, and one…
We report type-II superconductivity in the germanium clathrate compound, ${\mathrm{Ba}}_{8}{\mathrm{Ga}}_{16}{\mathrm{Ge}}_{30}$ with critical temperature, ${T}_{c}=7.5\ifmmode\pm\else\textpm\fi{}0.2\mathrm{K}$ as determined by magnetic susceptibility measurements. Barium atoms occupy cage voids provided by a covalent…
The synthesis of and spectroscopic data on subazaporphyrins, subphthalocyanines, subnaphthalocyanines and their related compounds reported to date are summarized, together with the results of molecular orbital (MO) calculations from our laboratory. Thus the problems and key points in the synthesis of these subazamacro…
Procedures are described for normalizing structure-factor difference magnitudes, |Δ| F || SIR = || F Der | − | F Nat || ≤ | F Heavy | or |Δ| F || SAS = || F + h | − | F − h || ≤ 2| F ′′|, to prepare data for probabilistic direct methods phasing to determine heavy-atom or anomalous-scattering substructures in SIR (sing…
The 35 Cl NMR spectroscopy of Cl - -intercalated hydrotalcite and the Ca-aluminate hydrate hydrocalumite (Friedel’s salt) demonstrates dynamical behavior of interlayer Cl - , the presence of dynamical order-disorder phase transitions in these phases, and significant differences in the transition temperatures and tempe…