Materials Literature
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Significant enhancements in the electrocatalytic oxidation of HCOOH are obtained on deliberately stepped platinum surfaces with (111) terraces and (100) monatomic steps when bismuth is deposited on terrace and/or step sites. The bismuth-modified surfaces with higher step densities/narrower terrace widths exhibit highe…
Hydrous aluminosilicate glasses of composition NaAlSi 8 O 18, NaAlSi 3 O 8, NaAlSi 2 O 6, and NaAlSiO 4 have been studied with 1 H MAS, and 1 H/ 27 Al, and 1 H/ 23 Na TRAPDOR NMR spectroscopy. Two different environments for molecular water were identified. Three 1 H OH resonances (1.5, ca. 3.5, and 5−6 ppm) are observ…
The cubic mesoporous silica molecular sieves MCM-48 have been obtained as an energetically favorable mesophase via a synthesis route using the surfactant mixtures between alkyltrimethylammonium bromides and polyoxyethylene alkyl ethers, with sodium silicate as the silica source. The MCM-48 mesophase was stable under t…
In a previous work [ Macromolecules 1998, 31, 6426] the preparation technique of a latex of poly(β-hydroxyoctanoate) (PHO) obtained from Pseudomonas oleovorans grown at high cell density on sodium octanoate was presented. The resulting films displayed typical properties of thermoplastic elastomer. Depending on the exp…
Electronic energy transfer from [Cr(ox) 3 ] 3- (ox = oxalate) in three-dimensional (3D) anionic oxalate networks to encapsulated [Cr(bpy) 3 ] 3+ (bpy = 2,2‘-bipyridine) cations at 1.5 K was investigated by time-resolved luminescence spectroscopy. Two series of mixed crystals of nominal compositions [NaAl 1 - x Cr x (o…
Unsymmetrical porphyrazines, M[pz(H)(2)(R)(6)], with three substituted pyrroles (substituents, R = -NMe(2), propyl, or 4-tert-butylphenyl) at the periphery and one unsubstituted pyrrole have been synthesized from inexpensive and readily available materials. Linstead crossover macrocyclization of 8 with 9, 11, and 12 g…
The ligand field in HBr results in the splitting of the Br 3d orbitals into the 3d (d x 2 - y 2 , d xy ), 3d (d xz , d yz ), and 3d (d z 2 ) orbitals. In core ionized HBr, the stronger spin-orbit splitting removes the remaining degeneracies and results in five different Br 3d eigenstates from linear combinations of th…
The molecular hyperpolarizabilities and electronic properties of some azulene-containing chromophores have been investigated by employing AM1/FF and ZINDO/S-CI approaches. The calculation results show good agreement with the experimental values. It is found that the nonalternant azulene ring can be regarded as a more…
Monolithic optically clear aluminosilicate and alumina gels can be prepared directly from aluminum nitrate (and tetraethoxysilane) dissolved in 1-propanol. The role of aluminum atoms in the formation of the gel networks has been investigated by 27 Al magic angle spinning nuclear magnetic resonance, infrared spectrosco…
We report on the highly exothermic solid-state reaction between hexachlorobenzene and calcium hydride. Once ignited by a thermal spike, the reaction displays a self-sustaining character in the CaH 2 /C 6 Cl 6 molar ratio of 3:18. The high temperatures reached, i.e., 2550−2900 K, ensure a complete breakdown of the arom…
The molecular third-order optical nonlinearity γ R (second hyperpolarizability or nonlinear refractive index) was measured for a series of sulfur-rich molecules: sulfur (S 8 ), carbon−sulfur compounds, and metal thiolate clusters. Z -scan techniques (pulse width 27 ps, wavelength 527 nm) were used to measure these pro…
This paper is the second segment of an investigation into the reaction products of laser-ablated lanthanide metal atoms with O 2 . There is general agreement with previous gas-phase and matrix infrared observations of neutral lanthanide monoxides; the frequencies of monoxide cations and anions are original to this wor…
Nanocomposites of montmorillonite mineral with poly-4-vinylpyridinium salts (1,2-form) the quaternized ionene polymer (1,6-form) and poly-4-vinylpyridine (neutral form) have been synthesized and characterized. Only one macromolecular sheet of poly-4-vinylpyridinium polyelectrolyte or the quaternized polyelectrolyte en…
X-ray diffraction analysis demonstrated that a PEN film annealed from 160 to 260 °C crystallizes in the α crystal form while crystallization of PEN directly from the melt results in the β crystal form when T c > 200 °C and in the α form at lower T c . Infrared spectra from PEN samples containing α, β, and amorphous ph…
Spin dependent single electron tunneling in a ferromagnetic double junction is investigated theoretically in the limit of incoherent sequential tunneling. The junction consists of a small nonmagnetic metallic grain with discrete energy levels, which is connected to two ferromagnetic electrodes. We have developed a new…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPreparation of Macroporous Metal Films from Colloidal CrystalsPeng Jiang, Joel Cizeron, Jane F. Bertone, and Vicki L. ColvinView Author Information Department of Chemistry, Rice University Houston, Texas 77005 Cite this: J. Am. Chem. Soc. 1999, 121, 34, 7957–7958Public…
The reversibility, specificity, stability, and scaling of signal response to analyte mass were quantified for a porous silicon-based optical interferometric biosensor. The sensor system studied consisted of a thin layer (5μm) of porous silicon modified with Protein A. The system was probed with various fragments of an…
Vacuum emission of ballistic electrons from Au-SiO 2 -Si structures has been investigated for oxide layers of various thicknesses d ox = 13-500 nm. In particular for very thick layers and high field strength 5 MV cm -1 we measure electron energies up to 200 eV, that is 80% of the maximum ballistic drive energy E ball…
The photochromism of spiro[cyclohexadiene-indolines], the reversible bond cleavage at the spiro-carbon resulting in a colored merocyanine, is affected by solvent polarity. Photoexcited intramolecular charge transfer within the preserved spiro form of the molecule is favored in polar solvents, explaining the drop in me…
In this paper, a Stoner-Wohlfarth approach to magnetic hysteresis is used as a model for a ferromagnetic composite rod consisting of single domain `grains' with random orientations embedded in a non-magnetic matrix. The rod is considered to be under torsional stress, which means that the rod at each point on its outer…