Materials Literature
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Static and time-resolved optical measurements have been performed on a number of free-base and zinc dodecaarylporphyrins with varying degrees of fluorination of the peripheral aryl rings. These studies were performed in a variety of solvents of differing polarity and metal-ligating ability and at room and low temperat…
Desorption/ionization on porous silicon (DIOS) is a relatively new laser desorption/ionization technique for the direct mass spectrometric analysis of a wide variety of samples without the requirement of a matrix. Porous silicon substrates were fabricated using the recently developed nonelectrochemical H2O2-metal-HF e…
A systematic theoretical study using the density functional theory is performed to provide molecular-level understanding on the desorption of carbon monoxide from surface oxygen complexes that are formed in the gasification and combustion of coal. Particularly, a CO molecule release from carbonyl oxygen complexes in t…
We present a simple set of data structures, and a collection of methods for constructing and updating the structures, designed to support the use of cohesive elements in simulations of fracture and fragmentation. Initially all interior faces in the triangulation are perfectly coherent, i.e., conforming in the usual fi…
In this work, silver film over silica nanosphere (AgFON) surfaces are shown to be thermally stable, SERS-active substrates that are suitable for use in ultrahigh vacuum (UHV) conditions. The metal FON surface is a materials general, cost-effective, and highly SERS-active surface. The SERS activity and thermal stabilit…
We propose a mechanism of long-range coherent coupling between nuclear spins to be used as qubits in solid-state semiconductor-heterojunction quantum information processing devices. The coupling is via localized donor electrons which in turn interact with the two-dimensional electron gas. An effective two-spin interac…
The interactions of hydrogen with ceria have been the subject of several experimental studies, but whether hydrogen atoms enter the bulk or are merely chemisorbed on the surfaces is disputed. We combine first-principles calculations with thermodynamic arguments and conclude that the uptake of small amounts of hydrogen…
In this study, we have explored the first use of the siliceous MCM-41 molecular sieve as an additive to enhance the gas permeability characteristics of a high-performance polysulfone. For all gases tested (N 2, O 2, CO 2, CH 4 ), the permeability increased in proportion to the weight percent of MCM-41 present in the f…
Abstract Homopolymers of itaconic acid (PIA) and its copolymers with acrylamide (P(IA‐AAm) were synthesized using ceric ammonium nitrate (NH 4 ) 2 Ce(NO 3 ) 6 in combination with nitrilotriacetic acid (NTA) as redox initiator, and potassium persulphate at pH 1. The chain structures of the resulting products have been…
A pressure cell with an anvil made of sapphire and the other made of tungsten carbide, was constructed to process thin film samples using a high power Nd:YAG pulsed laser, in a regime of ultrafast quenching rate and confined geometry. The sapphire anvil worked as the optical window to the laser beam and also as a good…
We investigated the influence of grinding as a pretreatment prior to the emitter film formation of single-walled carbon nanotubes (SWNTs) on the field emission and the geometric properties of SWNTs. Field emission from emitter films composed of ground SWNTs was found to be dramatically enhanced as well as to be homoge…
Abstract The chemical modification of native wheat straw hemicelluloses with succinic anhydride using N,N ‐dimethylformamide/lithium chloride system as solvent and pyridine and/or 4‐dimethyaminopyridine as catalyst has been examined. In particular, the progress of the succinoylation reaction is studied as a function o…
Ultrasonic attenuation due to phonon-phonon interaction and thermoelastic relaxation are studied in Lanthanum Monochalcogenides in <110> direction at different higher temperatures. For evaluation of ultrasonic absorption coefficients the second and third order elastic constants (SOEC) and (TOEC) are also calculated. S…
Photoluminescence and Raman scattering experiments were performed on Si/SiO2 superlattices grown by radio frequency magnetron sputtering on Si, quartz and glass substrates. Increasing the Si layer thickness in the Si/SiO2 superlattice gave rise to an increased photoluminescence signal and a Raman signature for nanocry…
Silk fibroin is a simple protein expected to have functional applications in medicine and bioelectronics. The primary structure of this protein is quite simple, and the main secondary structures are β-sheet crystals and amorphous random coils. In the present study, we investigated pulsed laser deposition (PLD) of fibr…
The recently discovered superconductor MgCNi 3 crystallizes in the classical cubic perovskite structure. The electronic structures of the MgCNi 3- x M x (M = Co, Cu; x = 0, 0.5, 1.0) system have been calculated using the self-consistent tight-binding linear muffin-tin orbital method. The calculations showed that the F…
Iron containing diamond-like amorphous carbon (a-C:Fe) films were deposited by filtered cathodic vacuum arc technique. The influences of Fe content and substrate bias on the surface energy of the films were investigated. The surface energy of a-C:Fe films was determined by the contact angle measurement. Atomic force m…
We have simulated the size dependence of domain patterns in a two-dimensional (square shaped) constrained ferroelectric system by means of a time-dependent Ginzburg–Landau model. The theory incorporates elastic strain in the form of an effective long-range nonlocal interaction of the polarization. A nonferroelectric l…
The properties and mechanism of the magnetic phase transition of the perovskite-type Ti oxides, which is driven by the Ti-O-Ti bond angle distortion, are studied theoretically by using the effective spin and pseudospin Hamiltonian with strong Coulomb repulsion. It is shown that the A-type antiferromagnetic (AFM(A)) to…
Abstract The electron emission yields of insulators irradiated with ultra‐short pulsed X‐ray and electron beams differ significantly from those of metals. The main experimental results are reviewed and it is shown that the use of simple models for the transport and for the escape of the generated secondary electrons a…