Materials Literature
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Neutron scattering has been used to study the nature of the ferromagnetic transition in single crystals of ${\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}\mathrm{Mn}{\mathrm{O}}_{3}$ and ${\mathrm{La}}_{0.8}{\mathrm{Ca}}_{0.2}\mathrm{Mn}{\mathrm{O}}_{3}$, and polycrystalline samples of ${\mathrm{La}}_{0.67}{\mathrm{Ca}}_{0.33…
The synthesis and magnetic properties of three isostructural hexadecametallic manganese clusters [Mn(16)O(16)(OMe)(6)(O(2)CCH(2)Ph)(16)(MeOH)(6)] (1), [Mn(16)O(16)(OMe)(6)(O(2)CCH(2)Cl)(16)(MeOH)(6)] (2), and [Mn(16)O(16)(OMe)(6)(O(2)CCH(2)Br)(16)(MeOH)(6)] (3) are reported. The complexes were prepared by a reductive…
There's nothing confusing about the dimer (see picture) that forms from N-confused porphyrin! The dimer was obtained as a directly β–β-linked structure through a simple acid-catalyzed condensation reaction of the monomeric macrocycles, and the electronic interaction between the porphyrin subunits was studied for both…
We argue that the large Jahn-Teller (JT) distortions in ${\mathrm{Y}\mathrm{V}\mathrm{O}}_{3}$ and ${\mathrm{L}\mathrm{a}\mathrm{V}\mathrm{O}}_{3}$ should suppress the quantum orbital fluctuation. The unusual magnetic properties can be well explained based on local density approximation $+$ Hubbard U calculations usin…
Phytic acid (IP 6 ) and its salts are promising reagents to alleviate corrosion of metals, which are environmentally friendly and highly efficient, compared to some traditional inhibitors toxic to environment. This paper reports the studies of the structure and anticorrosion features of two kinds of the self-assembled…
Electrochemical impedance spectroscopy, Fourier transform infrared reflection−absorption spectroscopy, and cyclic voltammetry were employed to characterize polyelectrolyte multilayers (PEMs) fabricated with poly(styrenesulfonate) as the polyanion and the polypeptides poly- l -histidine, poly- l -lysine, and poly- l -a…
A series of four ligands based on a 5'-methyl-2,2'-bipyridyl framework substituted in the 6 position by a carboxylic acid, a phosphonic acid, a monoethyl ester phosphonic acid, or a diethyl ester phosphonic acid are described. The pK(a) values of all ligands and their assignments are determined by a combination of UV-…
Gas bubbles are the most potent naturally-occurring entities that influence the acoustic environment in liquids. Upon entrainment under breaking waves, waterfalls, or rainfall over water, each bubble undergoes small amplitude decaying pulsations with a natural frequency that varies approximately inversely with the bub…
A high-nitrogen compound, 3,6-di(azido)-1,2,4,5-tetrazine, was used as precursor for the preparation of carbon nanospheres (see SEM picture) and nitrogen-rich carbon nitrides. The conversions into both carbon-based materials are simple, occur under mild conditions (low temperature, no applied pressure), and require no…
Trace concentrations of polycyclic aromatic hydrocarbons (PAHs) have been successfully detected using surface-enhanced Raman scattering (SERS) spectroscopy. For such purpose, new SERS substrates have been developed, consisting of Ag nanoparticles, either in suspension or immobilized on glass, obtained by a new method…
Extraction processes of natural fibers can be performed by different procedures that include mechanical, chemical and biological methods. Each method presents different advantages or drawbacks according to the amount of fiber produced or the quality and properties of fiber bundles obtained. In this study, biological n…
We analyze the lineshape of x-ray diffraction profiles of GaN epitaxial layers with large densities of randomly distributed threading dislocations. The peaks are Gaussian only in the central, most intense part of the peak, while the tails obey a power law. The $q^{-3}$ decay typical for random dislocations is observed…
X-ray absorption near-edge spectroscopy (XANES) is used to study the N environment in bulk GaN and in GaN{y}As{1-y} epilayers on GaAs (001), for y \~5%. Density-functional optimized structures were used to predict XANES via multiple-scattering theory. We obtain striking agreement for pure GaN. An alloy model with nitr…
In control! Ag2S nanocrystals of predictable size and shape were synthesized from the precursor Ag(SCOPh) in the presence of an amine. Careful tuning of several parameters, such as the reaction temperature and the ratio of amine to precursor, led to Ag2S nanocrystals of varying morphology (red: nanocubes; blue: facete…
The thermal conductivity of the magnetically frustrated, ferroelectric YMnO3 exhibits an isotropic suppression in the cooperative paramagnetic state, followed by a sudden increase upon magnetic ordering. This unprecedented behavior without an associated static structural distortion probably originates from the strong…
Neutron scattering experiments were performed on the undoped and hole-doped Ca$_{2+x}$Y$_{2-x}$Cu$_5$O$_{10}$, which consists of ferromagnetic edge-sharing CuO$_2$ chains. It was previously reported that in the undoped Ca$_2$Y$_2$Cu$_5$O$_{10}$ there is an anomalous broadening of spin-wave excitations along the chain,…
Abstract We study the structural and electronic properties of isolated single‐wall carbon nanotubes (SWNTs) under hydrostatic pressure using a combination of theoretical techniques: Continuum elasticity models, classical molecular dynamics simulations, tight‐binding electronic structure methods, and first‐principles t…
In this paper, we report a simple melt impregnation method by using cheap mesophase pitches (MPs) as carbon precursors to prepare ordered mesoporous carbon with ordered graphitized pore walls at low temperature. This facile procedure includes melting MPs at 140 °C and impregnation of the melt into hexagonal or biconti…
We introduce a lattice model of dimers with directional interactions as a paradigm of molecular fluids or strongly correlated Cooper pairs in electronic systems. The model supports an intermediate phase that is common to both systems. There are two different ideal glasses having no moblity since they possess zero entr…
According to the spin-torque model, current-driven magnetic dynamics in ferromagnetic multilayers is determined by the transfer of electron spin perpendicular to the layers' magnetizations. By separating the largest contributions to the magnetic dynamics, we demonstrate that the dominant effect of spin-torque is rathe…