Materials Literature
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The characteristics and development of ceramic fiber and ceramic matrix composites(CMCs) prepared by polymer precursor pyrolysis have been reivewed. By analyzing the requirements for ceramic matrix oriented precursors, suitable physical/chemical properties, and the structural characteristics were proposed. The disadva…
The novel polyoxometalate [H(2)PW(9)Ni(4)O(34)(OH)(3)(H(2)O)(6)](2)(-) (1) has been synthesized and characterized by IR spectroscopy, polarography, elemental analysis, and magnetic measurements. An X-ray single-crystal analysis was carried out on Cs(2)[H(2)PW(9)Ni(4)O(34)(OH)(3)(H(2)O)(6)].5H(2)O, which crystallizes i…
Rheological and intensity (ILS) and dynamic light scattering (DLS) experiments were performed on semidilute aqueous mixtures of various compositions of oppositely charged and hydrophobically modified polyelectrolytes. The associative phase separation usually observed when mixing oppositely charged polyelectrolytes is…
First studies of the ternary system SnSe-Bi(2)Se(3) developed in 1960s and 1970s have revealed the existence of a nonstoichiometric trigonal phase with a wide range of compositions. In this study, an almost stoichiometric phase, corresponding to the composition SnBi(4)Se(7), has been identified and isolated. The struc…
Five model compounds (U u, U s, DPT, DMT, and MB) and two liquid crystalline poly(ester−urethane)s with inherent urethane and internal and external ester groups were prepared to monitor the hydrogen-bond (H-bond) interactions of urethane−urethane and urethane−ester (including internal and external esters). The model c…
Single-crystal films are essential for devices because the intrinsic properties of the material, rather than its grain boundaries, can be exploited. Cubic bismuth oxide has the highest known oxide ion mobility, which makes it useful for fuel cells and sensors, but it is normally only stable from 729 degrees to 825 deg…
Using density functional theory we study the dissociation of N 2, NO, and CO on transition metal surfaces. We discuss an efficient method to locate the minimum energy path and the transition state, and review recent calculations using this method to determine the transition state for dissociation of N 2 on Ru(0001) an…
Structural, energetical, and vibrational features of cagelike clusters mimicking the isolated hydroxyl group at the surface of siliceous materials, both free and interacting with an ammonia molecule, are studied ab initio at the B3-LYP/DZP level of calculations. Two minimal model clusters, H 3 SiOH and F 3 SiOH, and f…
The phase diagrams of Langmuir monolayers of heptadecanoic (C17), nonadecanoic (C19), and heneicosanoic (C21) acids have been determined from pressure-area isotherms, and from direct observations of the monolayers using Brewster angle microscopy. In this paper, we describe the observed domains, textures and phase boun…
Shocked glasses suffer a particular failure mode in which they lose strength behind a propagating front that is known as a failure wave. The glass shows high strength, which reduces after some time to a lower value as the failure front passes. Such behaviour is investigated using plate–impact loading experiments over…
Inelastic neutron scattering spectra of DNA-fibers are analyzed using ideas formulated recently in the field of the glass transition. The analysis reveals two temperatures, namely, T∼180–200 K and T∼230 K, at which the dynamics of DNA exhibits qualitative changes. The former is similar to the glass transition temperat…
In this work we develop a general method to examine cooperative diffusion, i.e., the partial dynamic structure factors, in multicomponent colloidal mixtures of spherical particles. Using a multivariable projection operator formalism based on the many-body Smoluchowski diffusion equation, we derive an exact microscopic…
Noncovalently linked electron donor-acceptor complexes consisting of either zinc tetraphenylporphyrin, (TPP)Zn, or zinc octaethylporphycene, (OEPc)Zn, as donor and pyridine appended C(60), py approximately C(60), as acceptor, via axial coordination of zinc, are reported. The UV-visible and (1)H NMR spectral studies re…
The Gay–Berne potential is proving to be a valuable model with which to investigate the behavior of liquid crystals using computer simulation techniques. The potential contains four independent parameters which control the anisotropy in the attractive and repulsive interactions. The choice of these parameters is not s…
We use molecular dynamic to simulate the directional growth of binary mixtures. our results compare very well with analitical and experimental results. This opens up the possibility to probe growth situations which are difficult to reach experimentally, being an important tool for further experimental and theoretical…
In this paper, we analyse the optical absorption in porous silicon . This is the first attempt to explicitly demonstrate that it is not possible to extract the band gap of such low dimensional nanostructures like porous silicon from a Tauc plot of Square Root(alpha h nu) vs (h nu) . These objections are also valid for…
To increase the excellent light-emitting properties of the Eu3+ ion, macrobicyclic and macrotricyclic ligands 7 – 10, incorporating a 18-membered tetralactam ring (acting as a lanthanide binding site) and a sensitizer group (2,2′-bipyridine or 2,2′-bipyridine 1,1′-dioxide moiety), were synthesized. The mononuclear and…
Poly- l -aspartic acid (PLAsp), which consists of ca. 50 Asp residues in a linear polypeptide, has been immobilized on controlled pore glass (CPG) and evaluated for its selectivity and binding strength in the complexation of metal ions from aqueous solutions. The carboxylate side chain of Asp (p K a = 5.4 ± 0.2) is th…
A novel polarizer made from two-dimensional photonic bandgap materials was demonstrated theoretically. This polarizer is fundamentally different from the conventinal ones. It can function in a wide frequency range with high performance and the size can be made very compact, which renders it useful as a micropolarizer…
Within the framework of a two-band tight-binding model, we have performed calculations of giant magnetoresistance, exchange coupling and thermoelectric power (TEP) for a system consisting of three magnetic layers separated by two non-magnetic spacers with the first two magnetic layers strongly antiferromagnetically ex…