Investigation of heat transfer enhancement in an enclosure filled with nanofluids using multiple relaxation time lattice Boltzmann modeling

This work investigates the heat transfer performance in an enclosure including nanofluids with a localized heat source. The velocity field is solved by multiple relaxation time lattice Boltzmann modeling (MRT) which has superior numerical advantages to single relaxation time lattice Boltzmann modeling (SRT); however, heat transfer is simulated separately using SRT-lattice Boltzmann modeling. The hydrodynamics and thermal fields are then coupled together using the Boussinesq approximation. The main objective of this study is to investigate the influence of several pertinent parameters such as Rayleigh number, solid particle volume fraction of nanoparticles, and the geometry as well as location of the localized heat source on the heat transfer performance of nanofluids. The results obtained from lattice Boltzmann modeling clearly indicate that heat transfer augmentation is possible using nano-fluids in comparison to conventional fluids, resulting in the compactness of many industrial devices.     

Microfluidic electrocapture-assisted mass spectrometry of membrane-associated polypeptides

To isolate membrane-associated proteins, which play diverse structural, catalytic, and regulatory roles in cells, they are often initially solubilized in detergents. Although detergents are essential for purifying membrane proteins, they tend to interfere strongly with subsequent analyses. A microfluidic method is presented here that surmounts this problem, allowing well-resolved mass spectra of test membrane-associated polypeptides, and their complexes with ions and detergents, to be acquired. As a front-end module it allows access to other advanced mass spectrometric strategies to be utilized toward defining biomolecular interactions. This opens up a new avenue for studying complexation and analysis of membrane proteins of general importance.     

Fourier transform infrared spectroscopic monitoring of sol-gel process in synthesis of PbS-TiO2 hybrid nanostructures

A typical hybrid nanostructure was prepared consisting of lead sulfide (PbS) nano-crystals, embedded in titanium oxide (TiO₂) using sol-gel method. The synthesis procedure was monitored by Fourier transform infrared spectroscopy. Spectroscopic investigations indicated that PbS nano-crystals are embedded in the TiO₂ matrix with no strong Ti-O-Pb-S bonding. The size of PbS hybrid nanostructures decreased with diminishing lead and sulfur mole concentrations. The smallest size of NCs has been obtained in 10% of mole concentration (30-45 nm particle size for the hybrid nanostructure). The morphology and microstructure of the nano hybrid was investigated by scanning electron microscope and X-ray diffraction.     

Mesoscale finite element prediction of concrete failure

The present paper studies the failure of concrete from the mesoscopic point of view. Biphasic cubic concrete samples containing spherical aggregates embedded in a homogenized mortar have been simulated using standard finite element method. Linear elasticity and damage-plasticity hypotheses are considered for the aggregates and mortar, respectively. Various triaxial loading conditions are assumed for each sample to generate adequate discrete failure points within the stress space. In the next step, the approximated failure surfaces of specimens are constructed using the Delaunay triangulation technique. The effects of mesostructural features such as aggregate grading curve, aggregate volumetric share, and more importantly the controlling parameters of mortar’s damage-plasticity constitutive model have been investigated. Finally, the failure modes of some selected samples have been reported and discussed.     

Polyacrylonitrile/α-Fe2O3 Hybrid Photocatalytic Composite Adsorbents for Enhanced Dye Removal

The potential of a novel α-Fe₂O₃/polyacrylonitrile (PAN) hybrid composite adsorbent to eliminate methylene blue (MB) from aqueous solution was evaluated. PAN was selected as the base composite. The presence of α-Fe₂O₃ as nanophotocatalyst on the surface of PAN introduced an efficient photocatalytic hybrid composite adsorbent for degrading MB. Effects of α-Fe₂O₃ nanopowder loading, pH, temperature, MB initial concentration, solar light, and contact time were investigated. Langmuir, Freundlich, and Temkin isotherms were applied to analyze the adsorption behavior. The Freundlich equation provided the best correlation with experimental data. Pseudo-first-order, pseudo-second-order, and intraparticle models were employed. Thermodynamic studies indicated an endotherm and spontaneous adsorption process in a defined temperature range.