نتایج جستجو برای: metal cluster

تعداد نتایج: 395377  

2008
Zhang Yu Guodong Tang Jianying Zhao Zhengjing Jiang

The title compound, [Cu(6)V(2)O(2)S(6)(C(6)H(8)N(2))(6)], is constructed from six CuS(3)N and two VOS(3) distorted tetra-hedra, forming an octa-nuclear V/S/Cu cluster with C(i) symmetry. The geometry around the V atoms is slightly distorted tetra-hedral, while there are large distortions from ideal tetra-hedral geometry for the Cu atoms. Adjacent metal-metal distances range from 2.693 (1) to 2....

Journal: :Physical review letters 2006
Davide Ricci Angelo Bongiorno Gianfranco Pacchioni Uzi Landman

Bonding of gold clusters, , 16, and 20, on MgO(100) and on thin MgO films supported on Mo(100) is investigated using first-principles density-functional theory. Enhanced adhesive bonding is found for clusters deposited on metal-supported MgO films of thickness up to about 1 nm, or 4 to 5 MgO layers, originating from electrostatic interaction between the underlying metal and metal-induced excess...

1996
S. Cassisi M. Castellani V. Castellani

We investigate the evolution of metal deficient stars, presentingH-burning isochrones covering cluster ages from800 Myr to 7 Gyr. Evolutionary evidences for selection effects in the metallicity distribution of very metal poor H-burning red giants are reported. The evolution of stars during central and shell He burning is further investigated, discussing the occurrence of He burning pulsators as...

2001
Véronique Buat

We studied the metal-poor globular cluster populations of a large variety of galaxies and compared their mean metallicity with the properties of the host galaxies. For this purpose, we constructed a comprehensive database of old, metal-poor globular cluster populations, hosted by 47 galaxies spanning about 10 magnitudes in absolute brightness. The mean metallicities of the systems are found to ...

Journal: :Environmental Health Perspectives 1984
C T Hunt Y Boulanger S W Fesik I M Armitage

113Cd-NMR studies have been used to elucidate the structure of the metal-binding sites in mammalian and invertebrate ( Scylla serrata) metallothioneins (MTs). Chemical shift data have shown that all Cd ions are tetrahedrally coordinated to four cysteine thiolate ligands with single cysteinyl sulfurs bridging adjacent metals. Homonuclear decoupling experiments have shown that the 7 g-atoms of me...

2001
A. O’Keefe

Direct optical absorption measurements ofjet-cooled metal clusters formed in a pulsed molecular beam have been made using a sensitive new absorption technique employing pulsed laser sources. Metal clusters and other metal containing species have been observed in this initial study. Absorption measurements of the Cu, ‘A;-‘E’ system reveal strong intensities for vibronic bands seen only weakly in...

Journal: :Environment international 2004
Kouji Adachi Yoshiaki Tainosho

Tire dust is a significant pollutant, especially as a source of zinc in the urban environment. This study characterizes the morphology and chemical composition of heavy metal particles embedded in tire dust and traffic-related materials (brake dust, yellow paint, and tire tread) as measured by a field emission scanning electron microscope equipped with an energy dispersive X-ray spectrometer (F...

Journal: :Pure and applied chemistry. Chimie pure et appliquee 2010
Julie A Aaron David W Christianson

Terpenoid synthases are ubiquitous enzymes that catalyze the formation of structurally and stereochemically diverse isoprenoid natural products. Many isoprenoid coupling enzymes and terpenoid cyclases from bacteria, fungi, protists, plants, and animals share the class I terpenoid synthase fold. Despite generally low amino acid sequence identity among these examples, class I terpenoid synthases ...

2005
W. T. Wallace D. W. Goodman

The optimization of oxide-supported metal clusters as heterogeneous catalysts requires a detailed understanding of the metal cluster–oxide interface. Model catalysts, prepared by deposition of a catalytically active metal onto a thin film oxide support, closely mimic real-world catalysts, yet are amenable to study using surface sensitive techniques. Surface science methods applied to model cata...

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