Materials Literature
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Alloys of copper and zinc (brass) have been widely used since Neolithic times due to the discovery that unlike regular copper this alloy can be worked ``cold'' around a 3:1 copper-to-zinc ratio. While it is now known that the as-grown system is a disordered fcc solid solution, no 3:1 ordered phase has yet been directl…
We predict the existence of stable nonlinear localized modes near the band edge of a two-dimensional reduced-symmetry photonic crystal with a Kerr nonlinearity. Employing the technique based on the Green function, we reveal a physical mechanism of the mode stabilization associated with the effective nonlinear dispersi…
A self-consistent mean-field theory explaining the thermal remagnetization (TR) of polycrystalline permanent magnets is given. The influence of the environment of a grain is treated by an inclusion approximation, relating the field inside the grain to the local field outside by means of an internal demagnetization fac…
We report on the properties of new ruthenocuprates Ru(1-x)Sr2GdCu(2+x)O(8-y) (x=0, 0.1, 0.2, 0.3, 0.4, 0.75) that extend the superconductivity found previously in RuSr2GdCu2O8 (Tc=45 K) to the solid solution with varied Ru/Cu ratios. The compounds have been synthesized in high-pressure oxygen atmosphere. The maximum t…
Microcanonical molecular dynamics study of the spontaneous alloying(SA), which is a manifestation of fast atomic diffusion in a nano-sized metal cluster, is done in terms of a simple two dimensional binary Morse model. Important features observed by Yasuda and Mori are well reproduced in our simulation. The temperatur…
The role of the synthesis conditions on the cationic Fe/Mo ordering in Sr2FeMoO6 double perovskite is addressed. It is shown that this ordering can be controlled and varied systematically. The Fe/Mo ordering has a profound impact on the saturation magnetization of the material. Using the appropriate synthesis protocol…
Surface-enhanced Raman scattering (SERS) substrates, consisting of arrays of electromagnetically coupled Ag nanoparticles on Si, were manufactured by electron-beam lithography. Substrate Raman efficiency, evaluated from the relative SERS intensities of the adsorbates rhodamine 6G and thiophenol, was found to increase…
We show that the Raman scattering technique can give complete structural information for one-dimensional systems, such as carbon nanotubes. Resonant confocal micro-Raman spectroscopy of an $(n,m)$ individual single-wall nanotube makes it possible to assign its chirality uniquely by measuring one radial breathing mode…
We report results on polarization-dependent photoinduced discharge in oriented fibers and films of ladder-type, electron-transporting polymer poly (benzimidazobenzophenanthroline), BBL. The photocarrier generation efficiency in the fiber which is indicated by the rate of discharge, is found to be distinctly higher for…
The electric field used in most electrorheological (ER) experiments is usually quite high, and nonlinear ER effects have been theoretically predicted and experimentally measured recently. A direct method of measuring the nonlinear ER effects is to examine the frequency dependence of the same effects. For a sinusoidal…
Spirobenzopyran derivatives carrying an oxymethylcrown ether moiety were synthesized, and their photochromism was studied in the presence of various metal ions in acetonitrile. The metal ion complexing ability of the crown ether moiety in crowned spirobenzopyrans affects both thermal isomerization and photoisomerizati…
Multibranched carbon nanotubes were grown by pyrolysis of acetylene in an anodic aluminum oxide (AAO) template with and without catalytic Co particles at the pore bottom. HRTEM structure analysis shows that both types of carbon nanotubes (CNTs) exhibit the same multiwall features, which consist of cylindrically stacke…
The shear-transformation-zone (STZ) theory of plastic deformation predicts that sufficiently soft, non-crystalline solids are linearly unstable against forming periodic arrays of microstructural shear bands. A limited nonlinear analysis indicates that this instability may be the mechanism responsible for strain soften…
A constitutive model is developed for the mechanical response of elastomers at finite strains. A polymer is treated as a network of linear chains linked by permanent (chemical crosslinks) and temporary (entanglements and van der Waals forces) junctions. Temporary junctions are assumed to be in two states: loose (passi…
We formulate a general theory of the dielectric response of a lattice with a structural transition and a polarization instability due to a soft-optic mode coupled to low energy electronic excitations by the electromagnetic fields. the electronic excitations considered are in two-limits; those of a low density of free-…
Pepsin−colloidal gold conjugates were prepared by a simple protein-friendly process and the enzymatic activity of the bioconjugates is reported. The pepsin−gold conjugates are obtained by mixing colloidal gold and protein solutions at pH = 3 and, thereafter, centrifugation, washing, and redispersion of the pepsin−gold…
From the acid-catalyzed condensation of aryl aldehyde and pyrrole a new type of fused expanded porphyrins, N-fused pentaphyrins NFP5-Y (24 π, yellow) and NFP5-R (22 π, red) were obtained in total yields of 2–19 %. The two normal-type porphyrins are quantitatively interchanged through a redox reaction (see scheme). DDQ…
The mystery of proficiency remains: The recently solved crystal structures of free orotidine monophosphate decarboxylase (ODCase) and of the enzyme in complex with inhibitors reveal unusual structural features. However, despite the similarities among the structures, several startling new mechanisms of action have been…
In this paper the monodomain-alignment of new photocrosslinkable fluorene bisacrylate model compounds and oligomers is reported. The orientation of the nematic LC- phase is preserved by photopolymerization in an oriented LC- network. Monodomain orientations of crosslinked fluorene bisacrylates are investigated by UV-V…
Nanopartikel mit hoher Photolumineszenz-Quantenausbeute werden neuerdings als mögliche Markierungssubstanzen für Biomoleküle und als Leuchtsubstanzen für optoelektronische Bauteile diskutiert. In einem koordinierenden Lösungsmittel konnten nun chemisch stabile, kaum toxische LaPO4:Ce,Tb-Nanokristalle (siehe Bild) im G…