Materials Literature
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We propose that the concept of liquids characterized by a given locally preferred structure (LPS) could help in understanding the observed phenomenon of polyamorphism. 'True polyamorphism' would involve the competition between two (or more) distinct LPSs, one favoured at low pressure because of its low energy and one…
“Picotubes”: A chiral tube is formed in the surprisingly clean Friedel–Crafts alkylation of a fully conjugated tubelike structure. Unlike helical carbon nanotubes synthesized at high temperatures, this chemically modified picotube is chiral by substitution. The two enantiomers were separated by chromatography on a chi…
The rheological behaviour of soft glassy materials results essentially from the interplay between shearing forces and an intrinsic slow dynamics. This competition can be described by a microscopic theory, which can be viewed as a nonequilibrium schematic mode-coupling theory. This statistical mechanics approach to rhe…
We show that the phonon–saddle transition in the ensemble of generalized inherent structures (minima and saddles) happens at the same point as the dynamical phase transition in glasses, that has been studied in the framework of the mode coupling approximation. The boson peak observed in glasses at low temperature is a…
We present structural and dynamical results of molecular dynamics simulation of vitreous silica undergoing a hydrostatic compression and decompression cycle at room temperature. Structural results as a function of density compare fairly well with experiments as well as with the longitudinal and transverse sound veloci…
Photolysis of perfluoroazooctane with diamond powders led to chemical modification of the surface with the introduction of perfluorooctyl ester and ether functional groups, the presence of which was confirmed by means of FT-IR, XPS and 19F NMR measurements.
In this work, we review, extend and discuss low-temperature specific-heat experiments, that we have conducted on different molecular (hydrogen-bonded) solids both in crystalline and glassy (either amorphous or orientationally disordered) phases. In particular, we have measured the low-temperature specific heat C p for…
RTV siloxane rubbers have been thermally aged in inert gas atmospheres and in the presence of moisture at temperatures up to 190°C. Toluene extractable matter measurements showed an increase in the levels of non-network fragments with age for those samples aged in sealed containers. Samples aged open to air did not sh…
Linear and Fourier-transform rheology were used to study the influence of the oscillatory shear amplitude, γ 0 , on the isothermal crystallization at 140 ° C of three commercial isotactic polypropylenes. The development of the crystallization was monitored through the time dependence of the dynamic storage modulus, G…
The dynamical behaviours of glass-forming liquids have been analysed extensively via computer simulations of model liquids, among which the Kob–Andersen binary Lennard-Jones mixture has been a widely studied system. Typically, studies of this model have been restricted to temperatures above the mode coupling temperatu…
The ageing of various glass forming materials (polycarbonate, polystyrene, polyvinyl acetate and triphenylethene) has been studied by differential scanning calorimetry. The variation of the relaxation enthalpy Δ H with the ageing time measured in a large domain of time is compared to the variation of volume Δ V report…
Newtonian viscosities of 19 multicomponent natural and synthetic silicate liquids, with variable contents of SiO 2 (41–79 wt%), Al 2 O 3 (10–19 wt%), TiO 2 (0–3 wt%), FeO tot (0–11 wt%); alkali oxides (5–17 wt%), alkaline-earth oxides (0–35 wt%), and minor oxides, obtained at ambient pressure using the high-temperatur…
Superconducting ${\mathrm{LaGe}}_{5}$ was synthesized by the reaction of La and Ge mixtures under a pressure of 5 GPa at 1200 \ifmmode^\circ\else\textdegree\fi{}C. It crystallized in the orthorhombic space group Immm (No. 71) with $a=4.0290(6),$ $b=6.307(1),$ and $c=9.978(2)\AA{},$ $V=253.54(6){\AA{}}^{3},$ and $Z=2.$…
Gold nanoparticles have been precipitated in the presence of a stiff polyphenylene dendrimer template with 16 thiomethyl groups on the outside. Powder X-ray diffraction analysis shows an average particle size of ∼3.7 nm; surprisingly, transmission electron microscopy (TEM) reveals a bimodal particle size distribution.…
Durch chemisches „Entkernen“ eines dendritischen Metalloporphyrin-Koordinationspolymers können organische Nanoröhren erzeugt werden (siehe schematische Formel). Zuvor wird die Peripherie des Oligomers durch Ringschlussmetathese intramolekular vernetzt.
The two-dimensional coordination polymer spin-crossover compound Fe(pyridine)2[Ni(CN)4] (1) and its isotope substituted analogues Fe(pyridine-D5)2[Ni(CN)4] (2) and Fe(pyridine-15N)2[Ni(CN)4] (3) have been synthesised and the isotope effect on the thermal spin-crossover behaviour has been studied using magnetic suscept…
We investigate the slow dynamics of strongly aggregated particle gels by diffusing wave spectroscopy (DWS) using a charge coupled device (CCD) camera as a multispeckle detector. The evolution of the slow dynamics after the gel-point is followed using two different techniques, the multispeckle method and a novel correl…
As a fundamental building block of a conductive magnetic macromolecule, a series of pyrrole derivatives carrying a nitronyl nitroxide (NN) group was prepared. Some of these derivatives afforded ground-state triplet diradical cations upon one-electron oxidation, and the difference in the spin multiplicities of the sing…
Degrading films: Surface-component-dependent and time-controlled degradation of a layer-by-layer (LbL) assembly comprising DNA and a cationic synthetic polymer is demonstrated through enzymatic hydrolysis by DNase I (see picture). The negatively charged enzyme is preserved on the cationic polymer surface in an inactiv…
Abstract Chelating agents are materials that are used to control undesirable reactions of metal ions. In oilfield chemical treatments, chelating agents are frequently added to stimulation acids to prevent precipitation of solids as the acid spends on the formation being treated. These precipitates include iron hydroxi…