Materials Literature
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Doping a perylene diimide organic semiconductor with a one-electron reduced perylene diimide containing a covalently bound counterion provides a well-characterized system for understanding doping in organic semiconductors. We obtain insight into the doping process by electron paramagnetic resonance (EPR) measurements…
The Verwey transition in magnetite is of fundamental importance for the understanding of metal-insulator transitions but, in spite of being the subject of many studies over the last century, its nature is not fully understood. This is even more true in the case of the magnetite surface, where the low dimensionality pl…
Structure and thermodynamics properties of liquid and amorphous ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$ have been investigated by Static Relaxation (SR) and Molecular Dynamics (MD) methods. Simulations were done in the basic cube under periodic boundary conditions containing 3000 ions with Born-Mayer type pair potentials.…
Measurements of the grain boundary character distribution in MgAl2O4 (spinel) as a function of lattice misorientation and boundary plane orientation show that at all misorientations, grain boundaries are most frequently terminated on {111} planes. Boundaries with {111} orientations are observed 2.5 times more frequent…
Using simulations of glassy systems under steady-state shear, we compare effective temperatures obtained from static linear response with those from time-dependent fluctuation-dissipation relations. Although these two definitions are not expected to agree, we show that they yield the same answer over two and a half de…
The first bent core mesogen carrying branched oligosiloxane units at both ends was synthesized and investigated with polarized light microscopy, DSC, X-ray diffraction of well aligned samples, and electrooptical methods. Two different antiferroelectric switching liquid crystalline phases were found. Both can be regard…
Rhodospirillum rubrum possesses a putative intracellular poly(3-hydroxybutyrate) (PHB) depolymerase system consisting of a soluble PHB depolymerase, a heat-stable activator, and a 3-hydroxybutyrate dimer hydrolase (J. M. Merrick and M. Doudoroff, J. Bacteriol. 88:60-71, 1964). In this study we reinvestigated the solub…
Hydrogen adsorption isotherms in single-wall carbon nanohorns (SWNHs) have been measured at 20 K. The pore volume from hydrogen adsorption is compared with that from nitrogen adsorption at 77 K to determine the density of confined hydrogen in the internal space of SWNHs; it indicates that the average density of confin…
Abstract We successfully synthesized hydroxypropylcellulose (HPC) and methylcellulose (MC) in high yields from cellulose in 6 wt % NaOH/4 wt % urea aqueous solutions at 25 °C. The cellulose derivatives were characterized with NMR, size exclusion chromatography/laser light scattering, gas chromatography (GC), ultraviol…
The nucleation of recrystallization in deformed and annealed metals is reviewed. The main mechanisms are thought to involve the growth of subgrains by low angle boundary (LAGB) migration in an orientation gradient or the strain induced boundary migration (SIBM) of existing boundaries. Although these mechanisms are rea…
We present a direct experimental measurement of an effective temperature in a colloidal glass of laponite, using a micrometric bead as a thermometer. The nonequilibrium fluctuation-dissipation relation, in the particular form of a modified Einstein relation, is investigated with diffusion and mobility measurements of…
Our entropic barrier hopping theory of glassy hard sphere colloidal suspensions is extended to include heterogeneity within a simple trap model framework. The origin of local domains, their size, and the corresponding static barrier fluctuations are attributed to mesoscopic density fluctuations of an amplitude control…
Dependent on the surface chemistry of gold nanocrystals of equal metal core size, two morphological types of self-organized block copolymer-particle blends are observed: (1) the segregation of the nanocrystals to the interfacial areas or (2) the preferential uniform distribution within one of the respective polymer do…
Single-wall carbon nanotubes (SWCNTs) represent an excellent example of materials by design with many of their outstanding properties predicted by theory prior to their synthesis. Both experimental and theoretical work on these novel nanowires continue to increase at a breathtaking pace. Herein we describe some of the…
We present a molecular dynamics study of force patterns, tensile strength and crack formation in a cohesive granular model where the particles are subjected to swelling or shrinkage gradients. Non-uniform particle size change generates self-equilibrated forces that lead to crack initiation as soon as strongest tensile…
Two series of yttrium aluminum garnets doped with erbium and ytterbium ions have been studied by single-crystal X-ray diffraction. The single crystals were obtained by the Czochralski method. The concentration of doping ions was established by the plasma emission spectroscopy method. For the Er series, it is equal to…
In this Letter we demonstrate that the phase segregated state observed in many rare-earth perovskites constitutes a sort of self-generated assembly of magnetic clusters in which magnetic interaction introduces collectivity among them. We show that the observed glassy behavior (memory, aging, etc.) can be perfectly und…
The bias dependent interface charge is considered as the origin of the observed non-ideality in current-voltage and capacitance-voltage characteristics. Using the simplified model for the interface electronic structure based on defects interacting with the continuum of interface states, the microscopic origin of empir…
We report the study of the quenching of quantum dots (CdSe) by gold nanoparticles at the single-molecule level. Double-stranded DNA is used as a rigid spacer to tune the distance between the two nanoparticles. The width of the fluorescent intensity distribution, monitored at different interparticle distances, reflects…
We engineered implantable small-diameter blood vessels based on ovine smooth muscle and endothelial cells embedded in fibrin gels. Cylindrical tissue constructs remodeled the fibrin matrix and exhibited considerable reactivity in response to receptor- and nonreceptor-mediated vasoconstrictors and dilators. Aprotinin,…