Materials Literature
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The development of cost-effective nanopowder production methods has been a major obstacle to the development and industrial utilization of nanostructured materials. This paper describes a new cost-effective production technology for these materials which combines both pulsed electrochemistry and pulsed ultrasound. Thi…
The Suzuki polycondensation of the amphiphilically equipped dibromobenzene derivatives 8 and 11 with benzene diboronic acid ester 12 to the new kind of polymeric amphiphiles 13 and 14 is described. They carry at each repeat unit either a hydrophobic alkyl chain and a hydrophilic dendron with oligoethyleneoxy chains (…
Polythiophene−transition metal hybrid materials based on cobalt salen have been prepared and shown to catalyze the reduction of O2. The conjugated nature of the polymer backbone allows for facile electron transfer from the polymer surface to the active metal centers to affect this reduction. Rotating ring−disk measure…
A chiral cyclohexane containing two photochromic diarylethene units was synthesized in an attempt to use it as a dopant for a photoresponsive liquid crystal. A stable photoswitching between nematic and cholesteric phases could be induced by the addition of a small amount of the chiral cyclohexane to a nematic liquid c…
Rheological behavior of the first eight generations of bulk polyamidoamine (PAMAM) dendrimers, having nominal molecular weights from about 500 to over 116 000, was investigated under steady shear, shear creep, and dynamic oscillatory shear within the temperature range from T g + 15 °C to T g + 105 °C. It was found tha…
Phosphatidylcholine vesicles provide reaction compartments for the synthesis of nanometer-size CdS, Zn y Cd 1 - y S, and Hg y Cd 1 - y S particles with size- and composition-tunable absorbance and luminescence features. Spectrophotometric and spectrofluorimetric measurements are consistent with crystalline, monodisper…
Nonlinear optical dendritic macromolecules, called azobenzene dendrons, were synthesized, and their conformational properties and molecular nonlinear optical properties were clarified by second-order nonlinear optical measurement. The synthesized molecules were modified by introducing 1−15 numbers of azobenzene branch…
Nanocrystals of ZnO have been produced by an alkoxide based synthesis involving diethylzinc, tert -butyl alcohol, ethanol, and water. The resulting ZnO is in the form of a powder made up of zincite crystallites in the size range of 3−5 nm. These crystallites aggregate together to form larger spherical particles. These…
A bulk polycrystalline sample of YBa_(2)Cu_(3)O_(7-δ) (δ\approx 0.1) has been irradiated by γ-rays with ^{60}Co source. Non-monotonic behavior of T_{c} with increasing irradiation dose Φ(up to 220 MR) is observed: T_{c} decreases at low doses (Φ< 50 MR) from initial value (\approx 93 K) by about 2 K and then rises, fo…
Stability constants are reported for the coordination of pyridine and substituted pyridines to the alkylcobalt(III) complexes of octaethylporphyrin (OEP), t-octaethylchlorin (OEC), and ttt-octaethylisobacteriochlorin (OEiBC) in toluene solution. The stability constants correlate with the base strength of the nitrogeno…
The present study examines the relationship between thermal conductivity and planarity in polyimide films. The samples tested were specially prepared to range in orientation from three dimensionally random to highly planar. The molecular structure and orientation of the polyimide film have been characterized by polari…
Electrical resistivities, absorption spectra, and X-ray diffraction of one-dimensional bis(dimethylglyoximato)platinum(II), Pt(dmg) 2, have been studied in detail at high pressures. The resistivity drastically decreases with increasing pressure and reaches the minimum at around 6.5 GPa and then slowly increases with i…
{[oPONit]MnCl(μ-Cl)}2 is a di-chloro-bridged Mn(II) binuclear compound in which each Mn(II) is coordinated by (o-nitronyl nitroxide-phenyl)diphenylphosphine oxide acting as a bidentate ligand via the oxygen atoms of the PO and N−O groups. The spectrum of the low-lying states has been deduced from the magnetic and EPR…
In the present study, a dynamic model is developed for the calculation of the molecular weight and long chain branching distributions in a continuous solution metallocene-catalyzed ethylene polymerization reactor. The model is based on the fractionation of the total polymer chain population into a number of classes, e…
Sr- and Mg-doped LaGaO 3 powders with various dopant concentrations (La 1 - x Sr x Ga 1 - y Mg y O 3 - ( x + y )/2 where 0.02 ≤ x ≤ 0.2 and 0.02 ≤ y ≤ 0.2) were synthesized through a novel solution combustion route. X-ray diffraction patterns indicate orthorhombic structure for compositions 0 ≤ x ≤ 0.075 and 0 ≤ y ≤ 0…
To study the freezing/melting behavior of a confined N 2, CO, and Kr, we performed X-ray diffraction measurements of N 2, CO, and Kr confined inside the cylindrical pores of five kinds of siliceous MCM-41 with different pore radii ( R = 1.45−2.9 nm) as a function of temperature. Freezing and melting of these three mol…
Different sizes of Fréchet-type dendrons with a thiol group at the focal point were synthesized, well characterized, and used as building blocks for the preparation of self-assembled monolayers (SAMs) on metal surfaces. From the studies of the kinetic process of dendron thiol self-assembling on gold, it is shown that…
Nanocrystalline barium hexaaluminate has been successfully synthesized through the use of a reverse microemulsion as a medium for controlled hydrolysis and polycondensation of barium and aluminum alkoxides. The nanoparticles derived were characterized with electron microscopy, X-ray diffraction, and nitrogen adsorptio…
Synchrotron radiation X-ray powder diffraction data (SPDD) have been obtained for Ag[AgF4]2, Au[AuF4]2, Ag[AuF4], and Ag[AuF6]. Ag[AgF4]2 and Au[AuF4]2 are isostructural with Ag[AuF4]2, space group (SG) P2(1)/n, Z = 2, with the following: for Ag[AgF4]2 a = 5.04664(8), b = 11.0542(2), c = 5.44914(9) A, beta = 97.170(2)…
A series of ionic 4-amino-1-methylpyridinium benzenesulfonate salts have been prepared by quaternization reaction of 4-aminopyridine with methyl benzenesulfonates having a substituent of hydroxy, methoxy, methyl, chloro, or bromo group at para position. The X-ray structure analysis has been performed for their single…