Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPlant Growth Regulatory Indoles from the Sponges Dysidea etheria and Ulosa ruetzleriJohn H. Cardellina II., David Nigh, and Bradford C. VanWagenenCite this: J. Nat. Prod. 1986, 49, 6, 1065–1067Publication Date (Print):November 1, 1986Publication History Published online1 Jul…
Abstract The kinetic study of the mechanism for the reaction of the initial stages of the electropolymerization of 1-pyrenamine (PA) in an acetonitrile solution was carried out by cyclic voltammetry (CV) and double potential-step chronoamperometry (DPSCA). The experiments were conducted at various time windows (i.e.,…
Several hypotheses are advanced for resource relationships among planktonic diatoms in African freshwater lakes that are consistent with the light and nutrient conditions of the lakes and the extant and fossil distributions of the diatom species in them. The hypotheses are all testable and are potentially powerful too…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStudies of composition and crystallinity of bacterial poly(β-hydroxybutyrate-co-β-hydroxyvalerate)Steven Bloembergen, David A. Holden, Gordon K. Hamer, Terry L. Bluhm, and Robert H. MarchessaultCite this: Macromolecules 1986, 19, 11, 2865–2871Publication Date (Print):Novembe…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure and selectivity in host-guest complexes of cucurbiturilWilliam L. Mock and Neng Yang ShihCite this: J. Org. Chem. 1986, 51, 23, 4440–4446Publication Date (Print):November 1, 1986Publication History Published online1 May 2002Published inissue 1 November 1986https://…
A rigorous coupled-wave analysis for metallic surface-relief gratings is presented. This approach allows an arbitrary complex permittivity to be used for the material and thus avoids the infinite conductivity (perfect-conductor) approximation. Both TE and TM polarizations and arbitrary angles of incidence are treated.…
A review is given of the studies of the dimensionality characteristics of percolation clusters. The purely geometric nature of a percolation phase transition and the great variety of the quantities exhibiting critical behavior make this geometric approach both informative and useful. In addition to the fractal dimensi…
The direct determination of carbon–carbon bonding in amorphous carbon thin films has been performed by core-electron energy-loss spectroscopy and cross-polarization magic-angle spinning 13C nuclear magnetic resonance (NMR) for a series of varying band-gap amorphous carbon films (1.1–3.0 eV). The amorphous carbon films…
The question of whether scattering by the almost-periodic lattice potentials of recently discovered metallic quasicrystals is able to explain the recently observed short mean free paths (about 1 \AA{}) in these materials is discussed. It is shown that scattering by a three-dimensional, almost-periodic potential cannot…
Low density lipoprotein (LDL) doped with the anticancer mixture of hematoporphyrin derivatives Photofrin II (P2) competes with native LDL for binding to fibroblast receptors, despite a slight increase in the negative net charge related to the presence of acidic residues of porphyrins. P2 delivery to fibroblasts can be…
We report a new approach to the study of electron spectral clustering and wave-function scaling in several one-dimensional quasiperiodic systems. The approach is based on renormalization-group ideas. We introduce a novel decimation technique which generates a simple physical picture of the electron spectral behavior a…
The magnetic properties of surfaces are now being explored with electron spectroscopies that use electron spin polarization techniques. The increased activity in surface magnetic measurements with polarized electron beams is spurred by new scientific and technological challenges and is made feasible by recent advances…
Techniques for analyzing the structure and composition of solid surfaces with electron and photon beams often cause radiation damage in samples. Damage-producing processes compete with information-producing events during measurements, and beam damage can be a serious perturbation in quantitative surface analysis. Ther…
The conductivity σ of highly pure, thin zinc oxide films is investigated in the temperature range 500 to 1000 K and in the oxygen pressure range 0.1 to 15 kPa. The results reveal that two competing equilibria are responsible for the conductivity behaviour. In the high-temperature range the activation energy of σ is 1.…
Cristallisation dans le systeme orthohombique, groupe Pbca et affinement jusqu'a R=0,042. La structure est constituee de 3 tetraedres H 2 PO 3 non equivalents cristallographiquement, de molecules d'eau et d'atomes Mn et Na hexacoodines
From structural results previously reported the equilibrium conditions for ion-ion correlations in \ensuremath{\beta}-alumina are obtained. This provides a theoretical confirmation of the Beevers-Ross--mid-oxygen (BR-mO) model stability which whatever is the composition (1(5/3)) reveals itself to correspond to a lower…
We consider a finite superlattice consisting of unit cells with quantum wells filled with different types of carriers. The density-density correlation function is calculated with use of the random-phase approximation. The theory of resonant Raman scattering and inelastic electron scattering is formulated. The general…
The absorptances of 633-nm photons by silver island films formed on room temperature substrates were measured in an attenuated-total-reflection geometry by the photoacoustic method as a function of the angle of photon incidence. From the data obtained for s-polarized light ∊″, the effective dielectric function for the…
Long-range and local orders for ion-rich \ensuremath{\beta}- and \ensuremath{\beta}''-alumina are determined from conventional crystal-structure determinations and x-ray diffuse scattering. Both materials exhibit composition close to 1.66 ${\mathrm{Na}}^{+}$ per unit plane cell with a compensation mechanism exclusivel…
We study and compare plasmon spectra in semiconductor superlattices with periodic, quasiperiodic (e.g., Fibonacci sequence), and random spacings. Novel mode structures are found in the quasiperiodic cases, particularly for low values of level broadening that arises from inherent disorder effects. We discuss critically…