Performance characteristics of a new structured packing

A new structured packing using carbon fibres, called Sepcarb^® 4D, is presented. This packing has several attractive properties, such as high voidage (ε=94%) and high effective area (a=420 m² m^?3). These properties are advantageous for packing used as a gas–liquid contactor for separation units. To determine the internal characteristics of this packing, we performed several experiments using a 150-mm-internal-diameter column. Firstly, hydrodynamics experiments were conducted using an air–water counter current flow to determine the pressure drop (for both dry and wet packing) and flooding point. Secondly, the mass transfer efficiency was determined in terms of HETP (height equivalent to theoretical plate) by total reflux experiments with an n-heptane/cyclohexane mixture at atmospheric pressure. Hydrodynamic performance and mass transfer efficiency were compared with those of packings generally used in distillation and absorption.     

Microrheology: new methods to approach the functional properties of food

Three configurations have been developed to improve the understanding of structural element interactions in food material during deformation. The three configurations combine an inverted confocal scanning laser microscope (CSLM) and a cell that can apply to the sample a specific deformation: continuous shear, linear oscillatory shear and biaxial extension (compression).In the continuous shear and oscillatory shear configurations (OSCs), a zero-velocity plane is created in the sample by moving two plates in opposite direction, maintaining stable observation conditions of the structural behaviour under deformation. The OSC allows simultaneous application of CSLM and diffusing wave spectroscopy, a multiple light scattering technique. The third configuration (compression configuration) allows observation at a stagnation point during rheometric measurements. The configurations accept semi-liquid products (dressing, sauces, dairy products, etc.) for investigations in area such as aggregation, gelation, interactions at interface, coalescence, break-up.     

Densification of alumina by SPS and HP: A comparative study

In this study, the densification of alumina by spark plasma sintering (SPS) was investigated and compared to conventional hot pressing. It was shown that SPS is very effective in the sintering of alumina leading to higher densities and allows to work at lower temperatures and with shorter sintering cycles. The effect of the heating rate is dependent on the heating mode (SPS or HP). The identification of active sintering mechanisms was attempted by an isothermal and an anisothermal methods, showing that other mechanisms probably related to electrical effects enhance the densification. We suggest the higher contribution of surface diffusion mainly during the initial stage of sintering and an influence of the presence of impurities segregated at the grain boundaries. They could create conductive layers and also introduce ions with a lower valence than Al³⁺; defects are created in the surface layers and the diffusion of the species is increased.     

Natural Ligands of Porcine Olfactory Binding Proteins

Knowledge of endogenous ligands of olfactory binding proteins is a prerequisite for studying their role in odor and pheromone transduction. Here, we report the extraction, derivatization, and characterization by gas chromatography-mass spectrometry of the natural ligands of pig, Sus scrofa (L.), Von Ebner’s Gland protein (VEG) and odorant binding protein (OBP). We identified two isoforms (VEG1 and VEG2), which differed only by the linkage of an O-N-acetylglucosamine (O-GlcNac) group on VEG1. The natural ligands of VEG1 were characterized as two isomers of testosterone, whereas ligands of VEG2 and OBP were fatty acids or their derivatives. Our findings suggest that the binding specificity of VEG1 for steroids is governed by the presence of an O-GlcNac moiety on the protein. This specificity was confirmed by the binding of radiolabeled testosterone only by VEG1 in an in-gel binding assay. This is the first evidence for a post-translational modification in the process of odorant discrimination by olfactory binding proteins.     

Gamma ray degradation of electrolytes containing alkylcarbonate solvents and a lithium salt

Lithium-ion batteries for space applications, such as satellites, are subjected to cosmic radiations, in particular, γ-irradiation. In this study, the effects of this radiation on electrolytes and their components used in the lithium-ion batteries are investigated. The conductivity and viscosity of the samples have been measured before and after the irradiation. The modifications are evaluated by spectral analyses such as Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (¹H and ¹³C NMR), solid phase microextraction-gas chromatography (SPME-GC) and gas chromatography-mass spectroscopy (GC-MS). The experimental results show that only the samples containing vinylene carbonate and/or the lithium salt LiPF₆ are degraded by γ-radiation.     

Multi-scale gas discharge simulations using asynchronous adaptive mesh refinement

The breakdown of a gas gap at high products of pd (pressure × distance) is a multi-scale phenomenon in both time and space. This is especially true when the plasma is interacting with a gas flow, a problem of considerable recent interest in the context of aerodynamic applications of surface discharges. This paper presents a contribution to the numerical modeling of such discharges. We describe here a new approach for adaptive meshing which is suitable for use with the explicit asynchronous integration scheme described in our previous publication. Rather than relying on a family of nested grids as is commonly done, this technique is based on a single unstructured mesh with possible non-conforming cells at the interface between coarse and fine areas. Substantial computational time saving has been achieved for a surface dielectric barrier discharge configuration of the kind proposed as plasma actuators for flow control.     

Additive manufacturing of alumina parts by indirect selective laser sintering and post processing

Innovative powder preparation and post-processing techniques can be employed to obtain high density ceramic parts by means of indirect selective laser sintering. Thermally induced phase separation (TIPS) was used to produce polymer and polymer–ceramic composite particles. The effect of polymer concentration, cooling rate, stirring and alumina particles on polymer and polymer–ceramic composite particles was investigated. Homogeneous spherical alumina–polypropylene (PP) composite powder was synthesized by TIPS for selective laser sintering (SLS). Green Al₂O₃–PP component parts with a density of 34% could be produced by conventional SLS of the polymer under optimized laser power, scan speed, scan spacing and powder preheating temperature. Various post-processing techniques like pressure infiltration (PI), warm isostatic pressing (WIPing) or a combination of both were applied to increase the green density of the Al₂O₃–PP SLM parts. Infiltrating the open porosity green SLS parts with a 30 vol% alumina-powder based ethanol suspension allowed to increase the sintered density, i.e. after polymer debinding and pressureless sintering in air at 1600 °C, from 38 to 64% of the theoretical density (TD). WIPing of the SLS and SLS/infiltrated green parts at 135 °C and 64 MPa allowed raising the green density up to 93 and 83% TD and a sintered density up to 89 and 88% TD, respectively.