Materials Literature
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Mesoporous silica materials with well-ordered hexagonal structure were synthesized under acidic conditions by using various acid sources HX. The induction time for the formation of mesostructural precipitation increases in the lyotropic series HNO 3 < HBr < HCl < H 2 SO 4 under the same acid concentration. The inducti…
Photoinduced orientational behavior of polymethacrylates with side chains (amorphous polymers, pMAz2 and C2MeO, and liquid crystalline polymers, C6MeO and C12MeO) with different alkylene spacer lengths ( n = 2, 6, 12) were investigated by means of polarized Fourier transform infrared (FT-IR) and UV−vis absorption spec…
Aluminosilicate MCM-41 materials with Si/Al ratio between 10 and 50 were prepared via direct mixed-gel synthesis, and their hydrothermal stability in boiling water was investigated using a variety of techniques including powder XRD, N 2 sorption studies, and elemental analysis. The incorporation of Al markedly improve…
A highly concentrated (17 vol.%) Fe-C nano-particle system, with a narrow size distribution $d = 5.4\pm 0.4$ nm, has been investigated using magnetic ac susceptibility measurements covering a wide range of frequencies (17 mHz - 170 Hz). A dynamic scaling analysis gives evidence for a phase transition to a low temperat…
A simulated annealing algorithm is employed to generate a stochastic model for a Berea and a Fontainebleau sandstone with prescribed two-point probability function, lineal path function, and ``pore size'' distribution function, respectively. We find that the temperature decrease of the annealing has to be rather quick…
The Tm-Ba-Cu-O solder can be successfully used to produce a superconductive joint between MT-YBCO parts. The peculiarities of solidification, phase formation, structure transformations and electromagnetic properties of MT-YBCO soldered with TmBa2Cu3O7-d are discussed.
Silicotitanates are nanoporous materials that have been used as selective ion exchangers for removing cesium from waste streams and catalysts for promoting oxidation and hydroxylation reactions. The local bonding configurations and network charge distribution are known to influence the selectivity and reactivity of th…
The first neutral pentaatomic tetracoordinate planar carbon molecules, CAl 3 Si and CAl 3 Ge, as well as their anions, CAl 3 Si - and CAl 3 Ge -, were experimentally observed in the gas-phase and characterized by ab initio calculations and anion photoelectron spectroscopy. A four-center bond involving ligand−ligand in…
Suspended gold nanowires were made in an ultra-high vacuum. The finest of them was 0.6 nanometer in diameter and 6 nanometers in length. By high-resolution electron microscopy, they were shown to have a multi-shell structure composed of coaxial tubes. Each tube consists of helical atom rows coiled round the wire axis.…
Nearly full color emission has been achieved using quantum dot (QD)–polymer composites. The fluorescence of the resulting composites spans the entire visible range with narrow emission profiles and high photoluminescence (PL) quantum yields. Moreover, mixed colors are easily produced by controlling the mixing ratio of…
We demonstrate the controlled and reversible telescopic extension of multiwall carbon nanotubes, thus realizing ultralow-friction nanoscale linear bearings and constant-force nanosprings. Measurements performed in situ on individual custom-engineered nanotubes inside a high-resolution transmission electron microscope…
A versatile low-temperature chemical approach utilizing an alkoxide-based hydrazide process was developed for the synthesis of nanometer-size aluminum nitride, oxynitride, and composite powders. The process consists of reacting aluminum tri- sec -butoxide and anhydrous hydrazine in acetonitrile at 80 °C to yield solid…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTβ-KMP2Se6 (M = Sb, Bi): Kinetically Accessible Phases Obtained from Rapid Crystallization of Amorphous PrecursorsJean D. Breshears and Mercouri G. KanatzidisView Author Information Department of Chemistry, Michigan State University East Lansing, Michigan 48824 Cite thi…
Cytochrome c peroxidase (CcP) can bind as many as two cytochrome c (Cc) molecules in an electrostatic complex. The location of the two binding domains on CcP has been probed by photoinduced interprotein electron transfer (ET) between zinc-substituted horse cytochrome c (ZnCc) and CcP with surface charge-reversal mutat…
Hyperbranched aromatic polyamide copolymers were prepared by direct polycondensation of 3-(4-aminophenoxy)benzoic acid (AB monomer) and 3,5-bis(4-aminophenoxy)benzoic acid (AB 2 monomer) in the presence of triphenyl phosphite and pyridine as condensation agents. The structure of resulting polymers was confirmed by IR,…
Particle detectors made from artificial diamond have great promise for future experiments in particle physics because they are far less vulnerable to radiation damage than any other detector type. We review the history of diamond detectors and describe their current state of development. We also discuss the evidence w…
Recent studies of charge-transfer salts of the ion bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) are reviewed, focusing in particular on experimental techniques which involve high magnetic fields and on data obtained since 1996. Novel experimental techniques developed in the past few years, including angle-de…
The Hybrid Monte Carlo algorithm is adapted to the simulation of a system of classical degrees of freedom coupled to non self-interacting lattices fermions. The diagonalization of the Hamiltonian matrix is avoided by introducing a path-integral formulation of the problem, in $d+1$ Euclidean space-time. A perfect actio…
The anomalous Darwin term, one of the recently derived relativistic corrections to the conventional theory of superconductivity, is analysed in detail. A new derivation of this term, much simpler than that given originally, is presented and used to interpret the term physically, in terms of fluctuations of the relativ…
We have constructed maximally-localized Wannier functions for prototype structures of solid molecular hydrogen under pressure, starting from LDA and tight-binding Bloch wave functions. Each occupied Wannier function can be associated with two paired protons, defining a ``Wannier molecule''. The sum of the dipole momen…