Materials Literature
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The thermal contact resistance between graphene and silicon dioxide was measured using a differential 3ω method. The sample thicknesses were 1.2 (single-layer graphene), 1.5, 2.8, and 3.0 nm, as determined by atomic force microscopy. All samples exhibited approximately the same temperature trend from 42 to 310 K, with…
The permittivity and permeability behaviors of the hollow cobalt nanochains composites have been investigated in 2–18 GHz. The permittivity presents two dielectric resonance peaks at about 12.3 and 14.5 GHz, respectively, which mainly results from the cooperative consequence of the hollow structure and the one-dimensi…
We have investigated the thermal conductivity of graphene nanoribbons (GNRs) with different edge shapes as a function of length, width, and strain using nonequilibrium molecular dynamics method. The initial GNR for the functional variations has dimensions of 2×11 nm2. Strong length dependence of thermal conductivity i…
A description of neutral and multiply charged fullerenes is proposed based on a stabilized jellium (structureless pseudopotential) approximation for the ionic background and the local density approximation for the sigma and pi valence electrons. A recently developed shell-correction method is used to calculate total e…
A dynamic crack tip equation of motion is proposed based on the autonomy of the near-tip nonlinear zone of scale $\ell_{nl}$, symmetry principles, causality and scaling arguments. Causality implies that the asymptotic linear-elastic fields at time $t$ are determined by the crack path at a {\bf retarded time} $t-τ_d$,…
This paper presents a study of electron spin dynamics in bulk GaAs at low temperatures for elevated optical excitation conditions. Our time-resolved Faraday rotation measurements yield sub-nanosecond electron spin dephasing-times over a wide range of n-doping concentrations in quantitative agreement with a microscopic…
The electric field dependence of the dielectric constant (dc-tunability) as a function of composition at a few temperatures was investigated for BaTiO 3 -based solid solutions. Dense and homogeneous BaZr x Ti 1 − x O 3 ceramics (ferroelectric: x = 0.10 and x = 0.15 and relaxor: x = 0.18) with high dielectric constant…
The dependence of the coercive field and remanent polarization on temperature was measured for a number of commercial soft PZT ceramics in the temperature range from −175°C to 150°C. It is found that for all ceramics investigated the curves E c vs. T have a peak in the low temperature region, typically between −100°C…
meso-Tetraarylporphyrins are synthesized from pyrrole and substituted benzaldehydes by a catalytic amount of I2 as catalyst and o-iodoxybenzoic acid (IBX) as oxidant in two steps and one flask. The advantages of this method include the use of inexpensive and easily available catalyst, avoidance of heavy consumption of…
The catalytic (C) and regulatory (R) subunits of protein kinase A are exceptionally dynamic proteins. Interactions between the R- and C-subunits are regulated by cAMP binding to the two cyclic nucleotide-binding domains in the R-subunit. Mammalian cells express four different isoforms of the R-subunit (RIalpha, RIbeta…
Abstract This review covers the drastic morphological changes, including division or birthing dynamics, and even spontaneous movements performed by molecular self-assemblies constructed by reactive amphiphiles with the imine group that connects hydrophilic and hydrophobic moieties. It turns out that the formation (deh…
The effect of internal fields on the activation energy of creep in polycrystalline ferroelectric ceramics is investigated. It is shown that the internal fields can be evaluated directly from the experimental curves for polarization creep under constant electric field. For this purpose a micro-mechanical model of therm…
The second- and third-generation multiple dendrimers based on naproxen in core and Asp(4–6) oligopeptides in periphery were synthesized in a convergent approach and well characterized by NMR and mass spectral (MS) techniques. These conjugates showed a high affinity to hydroxyapatite in vitro and provided an effective…
X-ray photoelectron spectroscopy (XPS), magnetic and dielectric studies were performed for flux grown PbFe 1/2 Nb 1/2 O 3 (PFN) single crystals. The core level XPS spectra show that the Pb, Nb and O ions exist in one valence state while Fe ions in two Fe 2+ and Fe 3+ states. Temperature dependences of magnetic suscept…
Heteropolyacid–phosphomolybdic acid has been found to be an efficient and recyclable catalyst for cyclotrimerization of acetophenones into 1,3,5-triarylbenzenes in good yields.
The ground states of the actinides and their compounds continue to be matters of considerable controversies. Experimentally, Americium-I (Am-I) is a non-magnetic dhcp metal whereas theoretically an anti-ferromagnetic ground state is predicted. We show that hybrid density functional theory, which admixes a fraction of…
The full potential all electron linearized augmented plane wave plus local orbitals (FP-LAPW + lo) method, as implemented in the suite of software WIEN2K, has been used to systematically investigate the structural, electronic, and magnetic properties of the actinide compounds AnN (An = Ac, Th, Pa, U, Np, Pu, Am). The…
Ab initio total energy calculations within the framework of density functional theory have been performed for atomic hydrogen and oxygen chemisorption on the (0001) surface of double hexagonal packed americium using a full-potential all-electron linearized augmented plane wave plus local orbitals method. Chemisorption…
We investigate the nonlinear evolution of the Bales-Zangwill instability, responsible for the meandering of atomic steps on a growing vicinal surface. We develop an asymptotic method to derive, in the continuous limit, an evolution equation for the two-dimensional step flow. The dynamics of the crystal surface is grea…
Fundamental theories governing the number of fiber intersections in random nonwoven fiber webs were developed based on the planar geometry of fiber midpoints distributed in a two-dimensional Poisson field. First, the statistical expectation and variance for the number of fiber intersections in unit web area were obtai…