Mechanical response of nanoporous gold

We report the results of computational tensile and compressive tests for model bi-continuous nanoporous gold structures using atomistic simulations with empirical many-body potentials and molecular dynamics. The results are compared with the predictions of scaling laws for coarser-scale foams and with available experimental data. We find a surprising substantial tension/compression asymmetry in yield due to the surface stress that sets the filament under compression, providing a bias favoring yielding in compression. We provide a model for our results based on a ligament strength value close to the theoretical strength of Au, and the surface stress. The model predicts a significant tension/compression asymmetry for ligament sizes below ～10 nm and pore collapse for ligament sizes below 1 nm. We also observe an unexpected compaction tendency under tension characterized by a decrease in the total volume of the sample of 15% for samples deformed under tension by 30%. The mechanism of the compaction involves a decrease in the average pore size and pore collapse resulting from plasticity within the ligaments.     

Wool bleaching with reducing agents in the presence of sodium laurylsulphate. Part 2 — bleaching with non-stabilised hydrosulphite

Wool bleaching with non-stabilised hydrosulphite in the presence of sodium laurylsulphate (SLS) at a concentration of 5 g/l provides far better whites than when bleaching without this surfactant. In addition to better whiteness and lower yellowness index, wools bleached with SLS incorporated into the bath have a cysteine content some 20–30% lower.     

Scalable Path Computation Flooding Approach for PCE‐Based Multi‐domain Networks

In this letter, we assess the scalability of a path computation flooding (PCF) approach to compute optimal end‐to‐end inter‐domain paths in a path computation element‐based multi‐domain network. PCF yields a drastically reduced network blocking probability compared to a blind per‐domain path computation but introduces significant network control overhead and path computation complexity. In view of this, we introduce and compare an alternative low overhead PCF (LoPCF) solution. From the obtained results, LoPCF leads to similar blocking probabilities to PCF while exhibiting around 50% path computation complexity and network control overhead reduction.     

A note on secret sharing schemes with three homogeneous access structure

A secret sharing scheme is a method which allows a secret to be shared among a set of participants in such a way that only qualified subsets of participants can recover the secret. The characterization of ideal access structures and the search for bounds on the optimal information rate are two important problems in secret sharing. This paper deals with these problems for 3-homogeneous access structures, that is, whenever the minimal qualified subsets have exactly three participants.     

SPH truncation error in estimating a 3D function

The SPH truncation error (ε_T) can be defined as the sum of the integral kernel and the particle approximation error in Smoothed Particle Hydrodynamics modelling. Following the procedure proposed by Quinlan et al. [16] for a 1D generic derivative, we have derived an approximated 3D formulation of ε_T in reproducing a generic function. This kind of estimation is implemented in some SPH models in order to reproduce density or some transported scalars. Then a corresponding sensitivity analysis of ε_T has been performed adopting regular and irregular distributions of particles, arranged within a cube, delimited by lateral walls at each side. The evolution of ε_T has been analyzed and compared to the proposed formulation, which has been numerically estimated under some simple conditions. The SPH truncation error has then been investigated on a simple free surface test case: a supercritical flow over a channel sill. We have developed some conclusions about the dependence of ε_T on the position of the particles (inner or boundary), the shape of the function to be reproduced (f), the kernel support size (h), the particle volumes (ω), the kernel function (W), a non-dimensional distance between the volume barycentre and the particle location (δ), and a geometric anisotropy index of the particle volumes (I). We have finally underlined the difference between non-consistent simulations and estimations using Shepard’s correction.     

The atomistic modeling of wave propagation in nanocrystals

This paper presents non-equilibrium molecular dynamics simulations of wave propagation in nanocrystals. The width of the traveling wave front increases with grain size, d, as d^1/2. This width also decreases with the pressure behind the front. When the results are extrapolated to micro-crystals, reasonable agreement with experimental data is obtained. In addition, this extrapolation agrees with models that only take into account the various velocities of propagation along different crystalline orientations without including grain boundary effects. The results indicate that, even at the nanoscale, the role of grain boundaries as scattering centers or as sources of plasticity does not increase significantly the width of the traveling wave. For more information, contact E.M. Bringa, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore CA 94550, USA; (925) 423-5724; fax (925) 422-4665; e-mail ebringa@llnl.gov.     

In vitro oxidative decarboxylation of L-2-hydroxy-4-methylthiobutanoic acid by L-2-hydroxy acid oxidase A from chicken liver

The aim of this study was to assess prospectively acid-base changes after severe birth acidaemia. Fourty-five term babies with severe acidaemia (median umbilical artery pH 6.99 [Range 6.74-7.05], mean base deficit 16.3 [SD 3.7] mmol/l) were prospectively identified. Pathological cardiotocographs were present in 32 (71%) prior to delivery and 39 (87%) were delivered operatively; 27 for fetal distress. Sixteen required intubation. At one hour of age, median pH was 7.29 [Range 7.04-7.45] and the change in pH correlated with one hour pCO2 (r = 0.62 p < 0.001). pH measurements were obtained in 11 of the 16 babies with a 1 hour pH < or = 7.25 and all values had recovered by this time. Five of this group were receiving oxygen. Of the 11 babies admitted to NICU, 1 died and 3 had evidence of encephalopathy, all of which were normal at follow-up [2-12 months]. Recovery of pH after severe birth acidaemia was evident at 1 hour of age and would appear to be complete by 4 hours.     

Central neurocytoma: clinico-pathological study of 5 cases and review of the literature

Five cases of central neurocytoma, confirmed by immunohistochemical and electron microscopy studies, are reported and 127 cases from the literature are reviewed. Central neurocytomas are more frequent than previously thought, and will be diagnosed with increasing frequency in the future, if intraventricular tumors with histological aspect of oligodendroglioma or ependymoma will be routinely studied by immunohistochemistry and electron microscopy. The occurrence of an intraventricular tumor with a typical MR aspect in a young patient should suggest preoperatively the diagnosis of neurocytoma. The positivity for synaptophysin and neuron specific enolase, the negativity for neurofilament protein and glial fibrillary acid protein, and the finding of elements of neuronal differentiation on electron microscopy, are the main pathological features of these tumors. Complete removal of the tumor mass without radiotherapy is the treatment of choice. The prognosis is usually favorable without recurrence.