Materials Literature
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The extreme polar morphology that has been observed for crystals of the stable form of a steroid is explained by a molecular dynamics simulations approach. The habit modification is caused by surface−solvent interactions, which affect the growth rate of the polar faces differently. The same effect was observed for the…
A generic non-equilibrium synthesis technique has been developed to produce novel transition metal oxide nanowires, including YBa 2 Cu 3 O 6.66, La 0.67 Ca 0.33 MnO 3, PbZr 0.58 Ti 0.42 O 3, and Fe 3 O 4 . Key to our success is the growth of vertically aligned single-crystalline MgO nanowires, which worked as excellen…
We consider a model Hamiltonian fitted on the ab-initio band structure to describe the electron-phonon coupling between the electronic $σ-$bands and the phonon E$_{2g}$ mode in MgB$_2$. The model allows for analytical calculations and numerical treatments using very large k-point grids. We calculate the phonon self-en…
The local, eigenfunction-weighted acoustic phonon density of states (DOS) tensor is calculated for a model substrate consisting of a semi-infinite isotropic elastic continuum with a stress-free surface. On the surface, the local DOS is proportional to the square of the frequency, as for the three-dimensional Debye mod…
The spin-density wave (SDW) state in thin chromium films is well known to be strongly affected by proximity effects from neighboring layers. To date the main attention has been given to effects arising from exchange interactions at interfaces. In the present work we report on combined neutron and synchrotron scatterin…
Neutron scattering investigations were carried out in PbMg$_{1/3}$Ta$_{2/3}$O$_3$ and BaMg$_{1/3}$Ta$_{2/3}$O$_3$ complex perovskites. The crystal structure of both compounds does not show any phase transition in the temperature range 1.5 -- 730 K. Whereas the temperature dependence of the lattice parameter of BaMg$_{…
We present studies on magnetic nano-structures with 3D architectures, fabricated using electrodeposition in the pores of well-ordered templates prepared by self-assembly of polystyrene latex spheres. The coercive field is found to demonstrate an oscillatory dependence on film thickness reflecting the patterning transv…
The electronic structure of ${\mathrm{TiO}}_{2}$ aerogels is studied by soft x-ray absorption near-edge structure (XANES) spectroscopy. High-resolution O K-edge and Ti ${L}_{2,3}$-edge XANES spectra of aerogels are compared with those of rutile, anatase, and unrelaxed amorphous phases of full-density ${\mathrm{TiO}}_{…
Reductive alkylation of single-walled carbon nanotubes (SWNTs) using lithium and alkyl halides in liquid ammonia yields sidewall functionalized nanotubes that are soluble in common organic solvents. Atomic force microscopy (AFM) and high-resolution tunneling electron microscopy (HRTEM) of dodecylated SWNTs prepared fr…
Using first-principles calculations we show that the adsorption of atomic hydrogen on graphene opens a substantial gap in the electronic density of states in which lies a spin-polarized gap state. This spin is quenched by the presence of a rotated C-C bond (a Stone-Wales defect) adjacent to or distant from the H atom.…
Nanometer sized whiskers (nanowires) offer a vehicle for the study of size-dependent phenomena. While quantum-size effects are commonly expected and easily predicted, size reduction also causes more atoms to be closer to the surface. Here we show that intensity relations of below-band-gap and band-edge luminescence in…
An amphiphilic hexa-peri-hexabenzocoronene self-assembles to form a pi-electronic, discrete nanotubular object. The object is characterized by an aspect ratio greater than 1000 and has a uniform, 14-nanometer-wide, open-ended hollow space, which is an order of magnitude larger than those of carbon nanotubes. The wall…
Abstract The influence of tetramethylthiuram monosulfide (TMTM) in the vulcanization process of natural rubber and butadiene rubber with dipentamethylene thiuram tetrasulfide (DPTT) was investigated. Vulcanization parameters as reaction rate and reversion varied when TMTM was added in NR‐DPTT formulations. Crosslinkin…
In this model, the matrix phase is defined to consist o f the cementitious materials, the water, and the aggregate fines (< 125 jum). The particle phase correspondingly consists of the remaining aggregates. The inputs o f the model are the properties o f each phase. The challenge is to describe and determine these pro…
Thin films of $({\mathrm{La}}_{0.6}{\mathrm{Pr}}_{0.4}{)}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$ were grown on ${\mathrm{NdGaO}}_{3}(110)$ and ${\mathrm{LaAlO}}_{3}(001)$ substrates by pulsed laser deposition. The substrate temperature was held at 820 \ifmmode^\circ\else\textdegree\fi{}C, and the oxygen pressure…
Abstract The different melting temperatures of N ‐methyl morpholine N ‐oxide (NMMO) hydrates in the cellulose–NMMO hydrate solution may be explained by the rather different crystal structures of NMMO hydrates, which are determined by the amount of the hydrates. The preparative process of cellulose–NMMO hydrate solutio…
Abstract Summary: New monomeric benzo[ de ]isoquinoline‐1,3‐dione blue emitting fluorophores, containing hindered amine stabilizer fragment have been synthesized under phase transfer catalysis conditions and their ability for “one‐step” optical bleaching and stabilization of poly(methyl methacrylate) has been demonstr…
The magnetic properties of Cu(2)(dca)(4)(2,5-me(2)pyz) have been reexamined. The extended structure of Cu(2)(dca)(4)(2,5-me(2)pyz) can be viewed in terms of Cu(2)(2,5-me(2)pyz)(4+) dimer units interconnected via mu(1,5)-dca ligands. The bulk magnetic susceptibility chi(T) and the isothermal M(H) of Cu(2)(dca)(4)(2,5-m…
A joint experimental and theoretical study has been carried out to rationalize the results of visible photoluminescence measurements at room temperature on Sr 1- x TiO 3- x (ST) perovskite thin films. From the experimental side, ST thin films, x = 0 to 0.9, have been synthesized following soft chemical processing, and…
Abstract Alkali treatment can change the structures and properties of cellulosic fibers. The aim of this work was to study the mechanism of structural changes of Newcell fibers treated with different alkali concentrations and two treatment methods. Raman spectra showed that the molecular conformation of Newcell fibers…