Materials Literature
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Silica-supported Pd−Au clusters were characterized by Pd K and Au L 3 extended X-ray absorption fine structure (EXAFS) spectroscopy and Au L 2,3 X-ray absorption near-edge structure (XANES) spectroscopy. Pd−Au/SiO 2 catalysts with Pd/Au atomic ratios of approximately 1:1 were prepared by coadsorption of [Pd(NH 3 ) 4 ]…
Condensation reactions of mono- and didodecyl-substituted-2,5-diformylthiophene with hydrazine, p -diaminobenzene, 2,7-diaminofluorene, and 1,5-diaminonaphatalene give the corresponding polyazines (PAZs) and polyazomethines (PAMs), which have been characterized by thermal, structural, and optical analyses. The former…
Polycondensation between the acceptor−donor monomer combination of squaric acid with 1-dodecyl- and 3-dodecylpyrroles provided conjugated macromolecules having two types of isomeric repeating units, depending upon the reaction conditions employed. Under azeotropic distillation using the 1-butanol−benzene solvent mixtu…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTADDITION / CORRECTIONThis article has been corrected. View the notice.Double-Twisted Helical Lamellar Crystals in a Synthetic Main-Chain Chiral Polyester Similar to Biological PolymersChritopher Y. Li, Donghang Yan, Stephen Z. D. Ch…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTAn Efficient Catalyst for Asymmetric Epoxidation of Terminal OlefinsJames P. Collman, Zhong Wang, Andrei Straumanis, Mélanie Quelquejeu, and Eric RoseView Author Information Department of Chemistry, Stanford University Stanford, California 94305-5080 Laboratoire de Syn…
Ab initio calculation results for the electronic structure of disordered bcc Fe(x)Al(1-x) (0.40.5.
Asymmetric biphenyl type polyimides (PI) were prepared by thermal imidization of polyamic acids (PAA) derived from 2,3,3‘,4‘-biphenyltetracarboxylic dianhydride (a-BPDA) and p -phenylenediamine (PDA) or 4,4‘-oxydianiline (ODA). The dynamic mechanical properties of these PIs were compared with those of the isomeric PIs…
Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS) in a reflection mode are compared as the methods for phase composition investigation of thin film oxide systems by ion profiling. As an example, the Al/Al2O3/Si and YBa2Cu3O7/CeO2/Al2O3 systems are considered. The adaptation of applied stat…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTHybrid Nanoparticles with Block Copolymer Shell StructuresKeith J. Watson, Jin Zhu, SonBinh T. Nguyen, and Chad A. MirkinView Author Information Department of Chemistry, Northwestern University 2145 Sheridan Road, Evanston, Illinois 60208 Cite this: J. Am. Chem. Soc. 1…
The basic formulation of the quantum mechanical/molecular mechanical (QM/MM) methodology is presented. Critical issues related to running a QM/MM calculation are described and the future prospects of this methodology are discussed in detail.
We have grown highly oriented lead zirconate titanate [Pb(Zr, Ti)O3 or PZT] films on oxidized silicon substrates using a thin MgO buffer layer (7–70 nm thick). Ferroelectric nonvolatile memory field-effect transistors (FETs) were successfully fabricated using the metal/PZT/MgO/SiO2/Si structure in conjunction with rad…
A detailed three-dimensional structural analysis of single-walled carbon nanotubes was carried out using a scanning tunneling microscope (STM) operated at room temperature in ambient conditions. On a microscopic scale, the images show tubes condensed in ropes as well as tubes which are separated from each other. For a…
The combined effects of mechanical stress and surface electromigration on the dynamics of transgranular voids in passivated metallic thin films are analyzed based on self-consistent dynamical simulations. Depending on the strength of the electric and stress fields, void morphological instabilities can lead to film fai…
A nematic liquid crystal in cylindrical pores of polycarbonate (Nuclepore) membranes with radii 25--400 nm was studied by dynamic light scattering. The fundamental mode of the orientational fluctuations shows a crossover from bulk behavior, dominated by bulk-elastic constant $K$, to a surface-dominated one, in which t…
We use atom-resolved scanning tunneling microscopy to evidence the formation of carbon atomic chains on the C-terminated $\ensuremath{\beta}\ensuremath{-}\mathrm{SiC}(100)$ surface. These carbon atom lines, which exhibit an extremely high thermal stability (up to $\ensuremath{\approx}1200\ifmmode^\circ\else\textdegree…
Magnetoelastic phenomena correlated with magnetoresistive ones have been investigated for bilayered manganite crystals, ${\mathrm{La}}_{2\ensuremath{-}2x}{\mathrm{Sr}}_{1+2x}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}$ ( $0.3\ensuremath{\le}x\ensuremath{\le}0.45$), by measurements of the striction parallel and perpendicular to…
The products of laser ablation of graphite in a nitrogen atmosphere have been studied by transmission electron microscopy and electron energy-loss spectroscopy. Using nickel and cobalt as catalyst, single-wall carbon nanotubes can be produced with a yield similar to that obtained in an inert gas. Nitrogen has not been…
The systematic analysis of high-resolution NMR data, bond lengths, and isotropic ${}^{13}\mathrm{C}$ chemical shifts of crystals of squaric acid ( ${\mathrm{H}}_{2}\mathrm{SQ}$) and its deuterated compound ( ${\mathrm{D}}_{2}\mathrm{SQ}$) yields convincing evidence that order-disorder and displacive features coexist a…
The basic formulation of the quantum mechanical/molecular mechanical (QM/MM) methodology is presented. Critical issues related to running a QM/MM calculation are described and the future prospects of this methodology are discussed in detail.
The question on the dominant driving mechanism (displacive or order-disorder) at each structural phase transition of KNbO3 is investigated by means of molecular dynamics simulations. To this purpose, we first develop a shell model by determining its potential parameters in order to reproduce the ferroelectric instabil…