We have carried out Molecular Dynamics simulations on a sodium borosilicate glass in order to analyze how the structure of the glass during irradiation is affected by the choice of the density in the liquid state before cooling. In a pristine form generated through the usual melt-and-quench method, both short- and medium-range structures are affected by the compressive or tensile environment under which the glass model has been generated. Furthermore, Na-rich areas are much easier to compress, producing a more homogeneous glass, in terms of density, as we increase the confinement during the quench. When the glass is subjected to displacement cascades, the structural modifications saturate at a deposited energy of approximately 8 eV/atom. Swelling appears for the glasses that were initially prepared under compression, while contraction is evident for the ones prepared under tension. We have equally prepared glass models using a fast quench method, and we have found that they present an analogous disorder as the glasses submitted to displacement cascades. Compared to the irradiated glass, we found that the magnitude of the modifications for the fast quenched glass is lower, most notably in terms of boron and sodium coordination, the percentage of non-bridging oxygens and in the ring distributions. This later result agrees with statements extracted from recent experimental works on nuclear glasses.

We present an explicit representation for the matrix product ansatz for sometwo-species TASEP with open boundary conditions. The construction relies on theintegrability of the models, a property that constrains the possible rates atthe boundaries. The realisation is built on a tensor product of copies of theDEHP algebras. Using this explicit construction, we are able to calculate thepartition function of the models. The densities and currents in the stationarystate are also computed. It leads to the phase diagram of the models. Dependingon the values of the boundary rates, we obtain for each species shock waves,maximal current, or low/high densities phases.

The first result of the present paper is to provide classes of explicitsolutions for integrable boundary matrices for the multi-species ASEP with anarbitrary number of species. All the solutions we have obtained can be seen as representations of a newalgebra that contains the boundary Hecke algebra. The boundary Hecke algebra isnot sufficient to build these solutions. This is the second result of ourpaper.

Motivated by a class of flux compactifications of type IIA strings on rigid Calabi-Yau manifolds, preserving N=2 local supersymmetry in four dimensions, we derive a non-perturbative potential of all scalar fields from the exact D-instanton corrected metric on the hypermultiplet moduli space. Applying this potential to moduli stabilization, we find a discrete set of exact vacua for axions. At these critical points, the stability problem is decoupled into two subspaces spanned by the axions and the other fields (dilaton and Kähler moduli), respectively. Whereas the stability of the axions is easily achieved, numerical analysis shows instabilities in the second subspace.

The mechanical properties of amorphous solids such as glasses or gels are currently a topic of intense research, with implications in material science as well in fundamental condensed matter physics. At the macroscopic scale, a distinctive feature of these materials is the slow plastic deformation that is observed when they are subject to a step stress. Remarkably, this slow creep regime is often interrupted by the sudden failure of the material, with no macroscopic precursors.Recent works focus on the interplay between irreversible rearrangements at the microscopic level, resulting from an applied deformation or stress, and the macroscopic mechanical behavior. In fact, even though material failure is ubiquitous in our everyday life, the underlying microscopic mechanisms are still not well understood, mainly because the direct observation of its precursors at the particle level is experimentally very challenging in atomic or molecular materials.In this work, we study the microscopic dynamics of a model colloidal gel under load, by coupling a small angle light scattering apparatus to a custom stress-controlled shear cell. We find that the gel creep consists of three regimes. Initially, non-affine displacements grow linearly with strain. These non-affine dynamics are fully reversible upon removing the applied stress, and are associated to heterogeneity of the local gel elasticity. In the second regime, non-affine displacements grow much slower with strain, but are associated to irreversible rearrangements. In the third regime, a sharp acceleration of the dynamics at small length scale is observed. These rearrangements are a dynamic precursor of material failure; remarkably they occur thousands of seconds before the macroscopic yielding of the gel.

Thermo-mechanically durable industrial polymer nanocomposites have great demand as structural components. In this work, highly competent filler design is processed via nano-modified of micronic SiO2/Al2O3 particulate ceramics and studied its influence on the rheology, glass transition temperature, composite microstructure, thermal conductivity, mechanical strength, micro hardness, and tribology properties. Composites were fabricated with different proportions of nano-modified micro-composite fillers in epoxy matrix at as much possible filler loadings. Results revealed that nano-modified SiO2/Al2O3 micro-composite fillers enhanced inter-particle network and offer benefits like homogeneous microstructures and increased thermal conductivity. Epoxy composites attained thermal conductivity of 0.8 W/mK at 46% filler loading. Mechanical strength and bulk hardness were reached to higher values on the incorporation of nano-modified fillers. Tribology study revealed an increased specific wear rate and decreased friction coefficient in such fillers. The study is significant in a way that the design of nano-modified mixed-matrix micro-composite fillers are effective where a high loading is much easier, which is critical for achieving desired thermal and mechanical properties for any engineering applications. Copyright © 2016 John Wiley & Sons, Ltd.

Wet acid oxidation treatment methods have been widely reported as an effective method to purify and oxidize the surface of industrial multi-walled carbon nanotubes (MWCNT). This work examines the use of a concentrated HNO3/H2SO4 mixture in an attempt to optimize the purification procedure of industrial MWCNT with diameter distribution statistics. It is shown that acid treatments of several hours are enough to purify the nanotubes. The electrical and thermal conductivities of epoxy composites containing 0.05-0.25 wt. % of acid-treated MWCNT has been studied. The electrical conductivity of the composites decreases by more than three orders, whereas the thermal conductivity of the same specimen increases very modestly as a function of the filler content.