Materials Literature
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This paper reports results of molecular dynamics simulations for a glassy polymer melt consisting of short, non-entangled chains. The temperature region studied covers the supercooled state of the melt above the mode-coupling critical temperature. The analysis focuses on the interplay of simple-liquid and polymer-spec…
In many interesting physical settings, such as the vulcanization of rubber, the introduction of permanent random constraints between the constituents of a homogeneous fluid can cause a phase transition to a random solid state. In this random solid state, particles are permanently but randomly localized in space, and a…
A statistical mechanical approach to granular material is proposed. Using lattice models from standard statistical mechanics and results from a mean-field replica approach we find a jamming transition in granular media closely related to the glass transition in supercooled liquids. These models reproduce the logarithm…
We propose that the salient feature to be explained about the glass transition of supercooled liquids is the temperature-controlled super-Arrhenius activated nature of the viscous slowing down, more strikingly seen in weakly bonded, fragile systems. In the light of this observation, the relevance of simple models of s…
A formally exact set of equations is derived for the description of non-equilibrium phenomena exhibited by classical liquids and glasses. With the help of a non-equilibrium projection operator formalism, the correlation functions and fluctuation propagators are expressed in terms of memory functions and time-dependent…
A scenario for systems with slow dynamics is characterised by stating that there are several temperatures coexisting in the sample, with a single temperature shared by all observables at each (widely separate) time-scale. In preparation for the study of granular rheology, we show within this framework that glassy syst…
The thermodynamics of glass-forming systems can be expressed in terms of the density of inherent structures, which correspond to the minima of the potential energy landscape. In previous work this approach has been applied to Lennard-Jones-type systems, yielding a density of inherent structures which to a very good ap…
Three 3-fold symmetric rigid backbone phenylacetylene nitrile molecules have been prepared to which one to six hydroxy side chains have been attached. These molecules were cocrystallized with silver(I) trifluoromethanesulfonate (triflate) to form microcrystalline porous solids. X-ray powder data show that all three cr…
The coupling model, based on fundamental properties of nonintegrable Hamiltonian systems (chaos), captures one important aspect of the many-body relaxation dynamics, namely the existence of a temperature insensitive crossover time, t c , when in its neighbourhood the fast independent relaxation of an individual unit a…
Four natural amino acids with hydrophobic nonpolar side group (alanine, phenylalanine, proline, and methionine) were examined and their activity on hydroxyapatite, HAP, crystallization was assessed. The method used was the constant composition technique, at low supersaturation levels. Crystallization took place exclus…
Several members of the RNase A superfamily are endowed with antitumor activity, showing selective cytotoxicity toward tumor cell lines. One of these is onconase, the smallest member of the superfamily, which at present is undergoing phase-III clinical trials as an antitumor drug. Our investigation focused on other int…
In this article we review the thermodynamics of liquids in the framework of the inherent-structure formalism. We then present calculations of the distribution of the basins in the potential energy of a binary Lennard-Jones mixture as a function of temperature. The comparison between the numerical data and the theoreti…
Band gaps in polythiophene ( T ) and the related polymers with a fused benzene ring ( TB, polythieno[3,4- b ]benzene) or a fused pyrazine ring ( TN, polythieno[3,4- b ]pyrazine) have been computed using a variety of methods. Geometries of oligomers up to octamers (AM1) and up to tetramers (B3LYP/6-31G*) have been opti…
The new reduced K 2 NiF 4 Co(II) phase, LaSrCoO 3.5 - x, is prepared by reduction of the Co(III) containing LaSrCoO 4 using H 2 gas and the new hydride solid−solid reduction methods. The hydride route is superior in both crystallinity and control of phase purity and allows access to reduced phases containing substanti…
The mechanical properties of cross-linked edible films based on calcium caseinate and two type of whey proteins (commercial and isolate) were investigated. Cross-linking of the proteins was carried out using thermal and radiative treatments. Size-exclusion chromatography performed on the cross-linked proteins showed t…
We formulate ten questions, covering outstanding aspects of the phenomenology of glassforming liquids, which we believe must be properly answered by any successful theory of structural glassformers. The questions range across thermodynamic, mass transport and vibrational dynamics phenomena. While these questions will…
An efficient approach to the syntheses of amphiphilic rod−coil diblock and coil−rod−coil triblock copolymers was developed. Each diblock copolymer consists of a perfectly monodispersed oligo(phenylene vinylene) covalently bonded to a poly(ethylene glycol) block with a very low polydispersity (<1.05). The structure and…
Computer simulations have been employed in recent years to evaluate the configurational entropy changes in model glass-forming liquids. We consider two methods, both of which involve the calculation of the `intra-basin' entropy as a means for obtaining the configurational entropy. The first method involves the evaluat…
This paper gives an introduction to and brief overview of some of our recent work on the equilibrium thermodynamics of glasses. We have focused on first-principles computations for simple fragile glasses, starting from the two-body interatomic potential. A replica formulation translates this problem into that of a gas…
The scaling laws describing the roughness development of crack surfaces are incorporated into the Griffith criterion. We show that, in the case of a Family-Vicsek scaling, the energy balance leads to a purely elastic brittle behavior. On the contrary, it appears that an anomalous scaling reflects a R-curve behavior as…