Equation of state and stability of the helium-hydrogen mixture at cryogenic temperature

The equation of state and the stability of the helium-molecular hydrogen mixture at cryogenic temperature up to moderate pressure are studied by means of current molecular physics methods and statistical mechanics perturbation theory. The phase separation, segregation and hetero-coordination are investigated by calculating the Gibbs energy depending on the mixture composition, pressure and temperature. Low temperature quantum effects are incorporated via cumulant approximations of the Wigner-Kirkwood expansion. The interaction between He and H2 is determined by Double Yukawa potentials. The equation of state is derived from the hard sphere system by using the scaled particle theory. The behavior of the mixture over a wide range of pressure is explored with the excess Gibbs energy of mixing and the concentration fluctuations in the long wavelength limit. The theory is compared to cryogenic data and Monte-Carlo calculation predictions. Contrary to previous similar works, the present theory retrieves the main features of the mixture below 50 K, such as the critical point and the condensation-freezing curve, and is found to be usable well below 50 K. However, the method does not distinguish the liquid from the solid phase. The binary mixture is found to be unstable against species separation at low temperature and low pressure corresponding to very cold interstellar medium conditions, essentially because H2 alone condenses at very low pressure and temperature, contrary to heliu

Adsorptive removal of direct dyes by low cost rice husk: Effect of treatments and modifications

In the present study, free, carboxymethyl cellulose (CMC)-immobilized, polyvinyl alcohol (PVA)-alginate immobilized and chemically treated rice husk biomass was used for the biosorption of Everdirect Orange-3GL and Direct Blue-67 dyes. Maximum biosorption capacity of free, immobilized and hydrochloric acid treated biomass was observed for both dyes at low pH. Comparative study of free, immobilized and HCl treated biomass showed that, the HCl treated biomass exhibited more biosorption capacity (29.98 and 37.92 mg/g) for Everdirect Orange-3GL and Direct Blue-67, respectively. Equilibrium time was less for HCl treated biomass when compared with immobilized biomass. The Langmuir type 1 and 2 models were best fitted to experimental data for free, CMC, polyvinyl alcohol-alginate immobilized and HCl treated biomass in case of Everdirect Orange-3GL, while the equilibrium data of Direct Blue-67 followed the Langmuir type 2 isotherm. Pseudo-second-order and Elovich kinetic models illustrated good fitness to all types of biomasses showing chemisorption nature of biosorption. The amount of dyes sorbed (mg/g) increased with increase in temperature. The values of Gibbs free energy (ΔG°) showed that reaction was spontaneous at high temperature.Key words: Biosorption, kinetics, thermodynamics, direct dyes, immobilization, pretreatments

Computational modelling of dynamic delamination in morphing composite blades and wings

Swiss National Science Foundatio

Dynamic response of blast loaded Hollow Cylindrical and Truncated Conical shells

Hollow cylindrical and truncated conical shells depict enhanced torsional and shear resistance compared to beams and plates and are ubiquitously used in structures in aeronautics, submarines, wind turbines, pressure vessels, and transmission pylons. Upon extensive localised blast, these elements undergo local and global deformation and failure. The detrimental damage to the shell depends on the stand-off and charge mass and is proportional to the emerged local dynamic stresses and inelastic deformations. Large localised translations relocate the structure’s original pivot point and induce global rotations about the new one which raises the probability of structural collapse. In this work, we examine large plastic deformations of hollow cylindrical and truncated conical shells subject to a range of pulse pressures emanated from high explosives. Fluid-Structure Interaction (FSI)-based Finite Element (FE) models were developed to discern the characteristics of blasts at various stand-offs and functions were proposed to link load parameters to structural, material, and geometric properties

Information security collaboration formation in organisations

This is an accepted manuscript of an article published by The Institution of Engineering and Technology in IET Information Security, available online: https://doi.org/10.1049/iet-ifs.2017.0257 The accepted version of the publication may differ from the final published version.Collaboration between employees in the domain of information security efficiently mitigates the effect of information security attacks on organisations. Collaboration means working together to do or to fulfil a shared goal, the target of which in this paper is the protection of the information assets in organisations. Information Security Collaboration (ISC) aims to aggregate the employees’ contribution against information security threats. This study clarifies how ISC is to be developed and how it helps to reduce the effect of attacks. The socialisation of collaboration in the domain of information security applies two essential theories: Social Bond Theory (SBT) and the Theory of Planned Behaviour (TPB). The results of the data analysis revealed that personal norms, involvement, and commitment significantly influence the employees’ attitude towards ISC intention. However, contrary to our expectation, attachment does not influence the attitude of employees towards ISC. In addition, attitudes towards ISC, perceived behavioural control, and personal norms significantly affect the intention towards ISC. The findings also show that the intention for ISC and organisational support positively influence ISC, but that trust does not significantly affect ISC behaviour.Published versio

On the computational derivation of bond-based peridynamic stress tensor

The concept of ‘contact stress’, as introduced by Cauchy, is a special case of a nonlocal stress tensor. In this work, the nonlocal stress tensor is derived through implementation of the bond-based formulation of peridynamics that uses an idealised model of interaction between points as bonds. The method is sufficiently general and can be implemented to study stress states in problems containing stress concentration, singularity, or discontinuities. Two case studies are presented, to study stress concentration around a circular hole in a square plate and conventionally singular stress fields in the vicinity of a sharp crack tip. The peridynamic stress tensor is compared with finite element approximations and available analytical solutions. It is shown that peridynamics is capable of capturing both shear and direct stresses and the results obtained correlate well with those obtained using analytical solutions and finite element approximations. A built-in MATLAB code is developed and used to construct a 2D peridynamic grid and subsequently approximate the solution of the peridynamic equation of motion. The stress tensor is then obtained using the tensorial product of bond force projections for bonds that geometrically pass through the point. To evaluate the accuracy of the predicted stresses near a crack tip, the J-integral value is computed using both a direct contour approximation and the equivalent domain integral method. In the formulation of the contour approximation, bond forces are used directly while the proposed peridynamic stress tensor is used for the domain method. The J-integral values computed are compared with those obtained by the commercial finite element package Abaqus 2018. The comparison provides an indication on the accurate prediction of the state of stress near the crack tip

Socio-Economic Factors Affecting the Income of Small-scale Agroforestry Farms in Hill Country Areas in Yemen: A comparison of OLS and WLS Determinants

Yemen is a less-developed country in the Arabian Peninsula, with only 3% arable land. An agroforestry land-use system has been practiced traditionally by small-scale farmers, but is associated with low productivity and income. A study has been undertaken to determine the socio-economic attributes of farmers that influence the financial performance of agroforestry and nonagroforestry farms in the Bura’a Mountain region. A survey was conducted of 150 farmers involved in both agroforestry and non-agroforestry. Both OLS and WLS regression were applied, and coefficients compared in terms of consistency and goodness of fit. Incomes of farmers were found to be influenced by education, area of land, livestock holding, family size, and whether coffee is grown, but not farmer’s age. The WLS method produced efficient and consistent results, whereas OLS regression was affected by the heteroscedasticity. The findings of the study indicate that the farmers of the study area are in need of financial and technical support from government to increase their income. Infrastructural development and public intervention in developing farmers’ technical know-how could enhance production and ensure the optimum use of land as well as soil and water conservation

Evidence for Two Modes of Synergistic Induction of Apoptosis by Mapatumumab and Oxaliplatin in Combination with Hyperthermia in Human Colon Cancer Cells

Colorectal cancer is the third leading cause of cancer-related mortality in the world-- the main cause of death from colorectal cancer is hepatic metastases, which can be treated with isolated hepatic perfusion (IHP). Searching for the most clinically relevant approaches for treating colorectal metastatic disease by isolated hepatic perfusion (IHP), we developed the application of oxaliplatin concomitantly with hyperthermia and humanized death receptor 4 (DR4) antibody mapatumumab (Mapa), and investigated the molecular mechanisms of this multimodality treatment in human colon cancer cell lines CX-1 and HCT116 as well as human colon cancer stem cells Tu-12, Tu-21 and Tu-22. We showed here, in this study, that the synergistic effect of the multimodality treatment-induced apoptosis was caspase dependent and activated death signaling via both the extrinsic apoptotic pathway and the intrinsic pathway. Death signaling was activated by c-Jun N-terminal kinase (JNK) signaling which led to Bcl-xL phosphorylation at serine 62, decreasing the anti-apoptotic activity of Bcl-xL, which contributed to the intrinsic pathway. The downregulation of cellular FLICE inhibitory protein long isoform (c-FLIPL) in the extrinsic pathway was accomplished through ubiquitination at lysine residue (K) 195 and protein synthesis inhibition. Overexpression of c-FLIPL mutant (K195R) and Bcl-xL mutant (S62A) completely abrogated the synergistic effect. The successful outcome of this study supports the application of multimodality strategy to patients with colorectal hepatic metastases who fail to respond to standard chemoradiotherapy that predominantly targets the mitochondrial apoptotic pathway. © 2013 Song et al

Estimation of key potentially toxic elements in arid agricultural soils using Vis-NIR spectroscopy with variable selection and PLSR algorithms

Potentially toxic elements (PTEs) pose a significant threat to soil and the environment. Therefore, the fast quantification of PTEs is crucial for better management of contaminated sites. Versatile technique such as Visible near-infrared spectroscopy (Vis–NIRS) (350–2,500 nm) has attracted tremendous attention for assessing PTEs and has achieved promising results combined with successful multivariate analysis. This research investigated the potential of Vis–NIRS combined with partial least squares regression (PLSR) and variable selection methods to assess key PTEs (Cd, Co, Cu, Cr, Pb, and Zn) in agricultural soils under arid conditions. The soil samples (80) were collected from a polluted area around Al-Moheet drainage, Minya Governorate–upper Egypt. The samples were scanned using an ASD FieldSpec-4 spectroradiometer. Simulated annealing (SA) and uninformative variable elimination (UVE) were used to select the effective wavelengths in predicting PTEs. PLSR was used to develop the spectral models using the full range (FR-PLS) and feature-selected spectra techniques SA (SA-PLS) and UVE (UVE-PLS). The results indicated that UVE-PLS models performed better than FR-PLS and SA-PLS models in predicting the key PTEs. The obtained coefficient of determination (R2) and the ratio of performance to deviation (RPD) were 0.74 and 2.48 (Cr), 0.72 and 2.03 (Pb), 0.62 and 1.86 (Cd), 0.59 and 1.78 (Cu), 0.52 and 1.68 (Co), and 0.46 and 1.41 (Zn), respectively. The results suggested that the UVE-PLS spectral model is promising for predicting Cr, Pb, and Cd, and can be improved for predicting Cu, Co, and Zn elements in agricultural soils

Simulations of galactic disks including a dark baryonic component

$\Lambda$CDM numerical simulations predict that the "missing baryons" reside in a Warm-Hot gas phase in the over-dense cosmic filaments. However, there are now several theoretical and observational arguments that support the fact that galactic disks may be more massive than usually thought, containing a substantial fraction of the "missing baryons". Hereafter, we present new N-body simulations of galactic disks, where the gas content has been multiplied by a factor 5. The stability of the disk is ensured by assuming that the ISM is composed out of two partially coupled phases, a warm phase, corresponding the observed CO and HI gas and a cold collisionless phase corresponding to the unseen baryons.Comment: 4 pages, 2 figures. To appear in the proceedings of "Formation and Evolution of Galaxy Disks", ed. J. Funes & E. Corsini. Higher resolution version may be downloaded at https://obswww.unige.ch/~revaz/public/Rome2007/revaz.pd