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141.
142.
A derivation is presented for the fraction of material transformed as a function of time, X(t), for 1-D transformations which occur via continuous nucleation and growth of particles with a distribution of growth velocities. The derivation includes the effects of interparticle shielding as well as shadowed nucleation prevention (“phantoms”). The analytical results are compared with simulations and found to be in close agreement. The shielding effects are more dominant than the phantom effects, though both are important when exact information regarding the extent of transformation is desired. 相似文献
143.
This paper introduces the concept of a finite net of dimension d. This is a generalization of the finite net of dimension three, due to Laskar and the finite net (of dimension two) due to Bruck. An association scheme is defined on this system which is then shown to form a partially balanced incomplete block design on an association scheme with d associate classes. 相似文献
144.
Adiabatic compressibility measurements are reported on solutions in hydrocarbon solvents of a low Mw high ethylene content, and of both high and low Mw low ethylene content ethylene–propylene copolymers. In all solutions the observed adiabatic compressibility was lower than the solvent value by an increment which was a function of the solvent type. Comparison of the data for a high and low molecular weight sample of the same copolymer indicates no molecular weight effects. Changes in the composition of the copolymer, as indicated by NMR spectroscopy, have only a slight effect on the adiabatic compressibility. The dominant feature of these studies is the apparent correlation of the chain length of the alkane solvent with the decrement in the compressibility. 相似文献
145.
146.
Films of the molecular nanomagnet, Mn12-acetate, have been deposited using pulsed laser deposition and its novel variant, matrix assisted pulsed laser evaporation. The films have been characterized by X-ray photoelectron spectroscopy, mass spectrometry and magnetic hysteresis. The results indicate that an increase in laser energy and/or pulse frequency leads to fragmentation of Mn12-acetate, whereas its chemical and magnetic integrity is preserved at low laser energy (200 mJ). This technique allows for the fabrication of patterned thin films of molecular nanomagnets for fundamental and applied experiments. 相似文献
147.
148.
Fuller AL Watkins RW Dunbar KR Prosvirin AV Arif AM Berreau LM 《Dalton transactions (Cambridge, England : 2003)》2005,(11):1891-1896
The synthesis and characterization of a new N3O donor ligand N-benzyl-N-((6-pivaloylamido-2-pyridyl)methyl)-N-(2-pyridylmethyl)amine (bpppa) is reported. Treatment of bpppa with Mn(II)(ClO4)2.6H2O in acetonitrile solution yielded the mononuclear [(bpppa)Mn(CH3CN)(H2O)](ClO4)2 (1) which was characterized by X-ray crystallography, elemental analysis, IR spectroscopy, mass spectrometry, and a solution magnetic moment measurement. Admixture of equimolar equivalents of bpppa and Mn(II)(ClO4)2.6H2O in methanol solution, followed by addition of 0.5 or 1 equivalents of sodium oxalate, yielded the binuclear complex [{(bpppa)Mn}2([mu]-C2O4)](ClO4)2 (2), which was characterized by X-ray crystallography, elemental analysis, IR spectroscopy, mass spectrometry, and solid-state magnetic measurements. While 1 is mononuclear, the formation of the binuclear oxalate derivative indicates that use of the bpppa ligand does not enable isolation of a complex that is structurally relevant to a proposed 1:1 Mn(II)-oxalate adduct in the catalytic cycle of the oxalate degrading enzyme oxalate decarboxylase. 相似文献
149.
Conan F Le Gall B Kerbaol JM Le Stang S Sala-Pala J Le Mest Y Bacsa J Ouyang X Dunbar KR Campana CF 《Inorganic chemistry》2004,43(12):3673-3681
Under strictly anhydrous conditions, no reaction occurs between Mo(2)(O(2)CCMe(3))(4) and tetracyanoethylene, TCNE, at room temperature, but after addition of 1 equiv of water, a reaction proceeds to form [Mo(2)(O(2)CCMe(3))(3)((NC)(2)CC(CN)CONH)], 1. The compound contains a quadruple-bonded Mo(2) unit and the 2,3,3-tricyanoacrylamidate anion as a ligand (TC3A), a very unusual hydrolyzed form of TCNE. Two different solid-state structures were obtained after crystallization of 1. Crystals obtained from CH(2)Cl(2) consist of a two-dimensional network, and crystals grown from a C(6)H(6) solution form a 1-D chain motif. In both cases, the TC3A ligand acts as a polydentate ligand involving a bidentate OCN bridging unit and two CN groups. The electrochemical and spectroscopic (IR, UV/vis/near-IR, NMR, EPR) properties of 1 support the formulation in solution as a discrete 1:1 complex of the TC3A donor ligand and a Mo(2) unit with no charge transfer. The coordinated TC3A ligand exhibits redox properties similar to those of free TCNE. 相似文献
150.
The new compound [Ag(2)(bptz)(3)][AsF(6)](2), prepared from the reaction of bptz with Ag[AsF(6)] in CH(3)CN, is stable in solution as well as the solid-state and exhibits an unprecedented propeller arrangement of three bptz ligands spanning two Ag(i) ions with [AsF(6)](-) anions located in the folds of the cation. 相似文献