Reactions of the elements within welded Ta containers at approximately 600 degrees C followed by slow cooling give new A(8)Tl(11)Pd(x) products from an apparently continuous encapsulation of Pd atoms into the pentacapped trigonal prismatic anions in the isotypic rhombohedral (R3 macro c) A(8)Tl(11) phases. All systems also produce other phases at x < 1 as well, the simplest being the cesium system in which only trigonal Pd(13)Tl(9) is also formed. Cs(8)Tl(11)Pd(0.84(1)) was characterized by single-crystal means as close to the upper x limit in that system (R3 macro c, Z = 6, a = 10.610(1) A, c = 54.683(8) A). The Pd insertion causes an expansion of the D(3) host anion, particularly about the waist, to generate a trigonal bipyramidal PdTl(5) unit (d(Pd-Tl) approximately 2.6-2.8 A) centered within a somewhat larger Tl(6) trigonal prism, the remainder of the Tl(11) cluster. Strong Tl cage bonding is retained. Extended Hückel calculations show significant involvement of all Tl 6s, 6p and Pd 4d, 5s, 5p orbital sets in the central and cage bonding. The last valence electron is considered to be delocalized in a conduction band, as in A(8)Tr(11) examples, rather than occupying an antibonding e' LUMO across a gap of approximately 2.4 eV. 相似文献
The preparation and subsequent imaging of a two-dimensional array of a genetically and chemically modified cowpea chlorotic mottle virus (CCMV) is described. The genetic mutation provides symmetrically dispersed exposed thiol groups on the outer surface of the virus capsid. These functional groups can be used to covalently bind the capsid to smooth Au substrate. AFM imaging suggests that the genetic mutation by itself does not promote array formation but, rather, aggregation through disulfide linkages. However, breaking the symmetry of the capsid using a solid-phase approach and chemically passivating the exposed thiol groups with iodoacetic acid results in a capsid with exposed thiols only on one side of the particle. These symmetry-broken capsids were able to form self-assembled monolayers (SAM) on a Au surface. 相似文献
Magnetic polarization of Mo atoms in Co96Mo4 alloy film and Co/Mo multilayered structures has been studied by X‐ray magnetic circular dichroism. Samples with Mo spacers of two different thicknesses (0.9 nm and 1.8 nm) were investigated. Mo atoms receive a magnetic moment of ?0.21μB in the alloy. In the multilayer with the thinner Mo spacer (dMo = 0.9 nm) the magnetic moment is much smaller (?0.03μB). In both cases the measured induced moment at the Mo site is oriented antiparallel to the moment at the Co atoms. The presence of the induced moment in the Mo spacer coincides with antiferromagnetic coupling between the Co component slabs. In contrast, neither measurable induced moment at the Mo site nor interlayer coupling between the Co layers has been found for the multilayer with the thicker Mo spacer. Possible mechanisms of the coupling associated with the induced moment are discussed in detail. 相似文献
The paper contains the results of a study on a promising combustion technology known as chemical looping combustion (CLC). The main advantage of CLC is the production of a highly concentrated CO2 stream without any energy penalty for its separation, together with NOx emissions reduction. The objective of this work was to examine novel oxygen carrier (OC) materials for their practical applications with gaseous fuel/air. We report a simple, economical and environmentally friendly method for the large-scale synthesis of OCs from wastes. The reactivity tests for OCs made from wastewater from a coking plant were performed in a thermogravimetric analyser. For selected temperatures, reduction–oxidation cycles were performed. The effect of temperature on the reaction rates, the effect of waste treatment and the oxygen transport capacity were determined. The waste material demonstrated good thermal stability and maintained its redox behaviour over cycling. ICP-OES and XRD data revealed these materials that contained beneficial amounts of Fe species and silicon oxide, which improved stability. The study showed that these waste materials are excellent examples of raw materials that can enable a decrease in OC production costs with the additional benefit of the practical management of post-wastewater sediments from coke oven wastewater plants.
Pion-deuteron elastic backward scattering atpπlab ~ 0.2–1.0 GeV/c is analyzed in terms of a two-particle exchange mechanism. Inclusion of isobarsΔ (1236) in the intermediate states, such that the initial or final deuteron is in aΔΔ configuration, produces qualitative agreement with the observed structure of the excitation function. IntermediateN′(1520) andN′(1535) states are found to be negligible. 相似文献