Materials Literature
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Crystal structures and magnetic properties were determined for two novel polymorphs of the complex [H2DABCO][Ni(mnt)2] [(H2DABCO)2+ = diprotonated 1,4-diazabicyclo[2.2.2]octane; mnt2- = maleonitriledithiolate]. For each polymorph, anions form a layered structure in which two kinds of dimers were observed. The adjacent…
We use classical molecular dynamics simulations to study the collapse of single (SWNT) and double-walled (DWNT) carbon nanotube bundles under hydrostatic pressure. The collapse pressure $({p}_{c})$ varies as $1∕{R}^{3}$, where $R$ is the SWNT radius or the DWNT effective radius. The bundles show $\ensuremath{\sim}30%$…
This paper introduces an experimental method that uses Axisymmetric Drop Shape Analysis-Profile (ADSA-P) to measure the surface tension of polymer melts in supercritical carbon dioxide. The method is verified by experiments in air and nitrogen, where reproducibility tests and statistical analyses are performed. The su…
The synthesis and characterization of a series of mixed W-Zr polynuclear Lindqvist-type complexes, deriving from hexatungstate [W6O19]2-, are described in this work. This family of compounds is built from {W5O18Zr}2- moieties as shown by the X-ray structures of the monomeric [W5O18Zr(H2O)(3-n)(DMSO)n]2- (n = 1 and 2)…
The spin structure of nanocrystalline zinc ferrite synthesized via a high-energy ball milling process was investigated by nuclear magnetic resonance obtained at various external magnetic fields and temperatures. Iron inversion induced in nanosized zinc ferrite drastically changes its magnetic property. Nanocrystalline…
A series of 10 ( 2 − 11 ) new chiral (salicylaldiminato)tin Schiff base complexes obtained from the Schiff base condensation of 4-(diethylamino)salicylaldehyde and various amino acids, in the presence of diphenyltin oxide, is reported together with the parent achiral ( 1 ) derivative. Compounds 2 − 7 crystallize in th…
Novel composite-gel membranes capable of regulating permeability in response to external temperature change are being explored. These membranes containing ordered nanochannels can act as “on−off” switches or “permeability valves”. The channels are designed to contain an ordered array of core−shell type magnetic polyst…
Comprehensive measurements of electrical transport properties under pressure, thermal conductivity, magnetic susceptibility, and room-temperature compressibility have been used to characterize SrCrO3 and CaCrO3 perovskites synthesized under high pressure. Comparison with other narrow-band perovskite oxides suggests th…
Local densities of fundamental physical quantities, including stress and heat flux fields, are formulated for atomistic systems involving three-body forces. The obtained formulas are calculable within an atomistic simulation, in consistent with the conservation equations of thermodynamics of continuum, and can be appl…
PURPOSE: To compare T(1) values of blood and myocardium at 1.5T and 3T before and after administration of Gd-DTPA-BMA in normal volunteers, and to evaluate the distribution of contrast media between myocardium and blood during steady state. MATERIALS AND METHODS: Ten normal subjects were imaged with either 0.1 mmol/kg…
ZnO is a wide band gap, naturally n-type semiconductor with great promise for optoelectronic applications; the main obstacle yet to be overcome is p-type doping. Nitrogen, the most promising candidate currently being pursued as a dopant, has been predicted to preferentially incorporate into the ZnO lattice in the form…
A new scenario of the mechanism of intriguing ferromagnetic properties in Mn-doped magnetic semiconductor (Ga,Mn)As is examined in detail. We find that magnetic features seen in zero-field cooled and field cooled magnetizations are not interpreted with a single domain model [Phys. Rev. Lett. 95, 217204 (2005)], and th…
Extreme pressure strongly affects the superconducting properties of "simple" elemental metals, such as Li, K, and Al. Pressure induces superconductivity in Li (as high as 17 K) while suppressing it in Al. We report first-principles investigations of the superconducting properties of dense Li, K, and Al based on a rece…
We synthesized Cu-In sulfide heterostructured nanocrystals from the thermal decomposition of a mixture of Cu-oleate and In-oleate complexes in dodecanethiol. By varying the reaction temperature and time, we were able to synthesize Cu-In sulfide nanocrystals with acorn, bottle, and larva shapes.
Molecular self-assembly offers new routes for the fabrication of novel materials at the nano-scale. Peptide-based nanostructures represent nano-objects of particular interest, as they are biocompatible, can be easily synthesized in large amounts, can be decorated with functional elements and can be used in various bio…
The low-energy electronic structure of icosahedral fullerenes is studied within the field-theory model. In the field model, the pentagonal rings in the fullerene are simulated by two kinds of gauge fields. The first one, non-abelian field, follows from so-called K spin rotation invariance for the spinor field while th…
Merrifield's Variational Ansatz is extended so as to cover the case of two electronic bands mixed by an Einstein phonon. The Hamiltonian is composed of the local and kinetic (hopping) energies in the absence of vibrations, the vibrational energy, and a mixing band-off-diagonal part linear in the electron-phonon coupli…
We present classical density functional theory calculations of the free-energy landscape for fluids below their triple point as a function of density and crystallinity. We find that, both for a model globular protein and for a simple atomic fluid modeled with a Lennard-Jones interaction, it is free-energetically easie…
Magnetization and high resolution neutron powder diffraction measurements on the magnetic shape memory compound Ni 2 Mn 1.44 Sn 0.56 have confirmed that it is ferromagnetic below 319 K and undergoes a structural phase transition which takes place at T M = 221 K on cooling and 239 K on warming. The high temperature pha…
A theory for the anomalous vibrational and thermal properties of disordered solids based on the model assumption of randomly fluctuating transverse elastic constants is presented. Mean-field expressions for the vibrational density of states and the energy diffusivity are derived with field-theoretical techniques. As i…