Kinetic Comparative Study on Aerodynamic Characteristics of Hypersonic Reentry Vehicle from Near-Continuous Flow to Free Molecular Flow

A scaled model of the X38-like configuration was simulated under hypersonic conditions by the direct simulation Monte Carlo method and the unified gas kinetic scheme. The inflow conditions considered several different flow regimes, from the near-continuum though the slip-transitional to the free molecule regime. Flow fields and surface properties were compared in details between two methods. Not only the density and temperature contours distribution but also the surface pressure, heat flux, friction distribution, both kinetic methods give fairly consistent results. Aerodynamics of the model under hypersonic rarefied conditions were also obtained and compared. The results given by both methods agreed with each other very well. The effects of the Knudsen number and angle of attack were assessed. At the absence of experimental results, it is meaningful to carry out comparative studies and accelerate both methods to further progress.

Scientific Approaches on Extraction, Purification and Stability for the Commercialization of Fucoxanthin Recovered from Brown Algae

The scientific community has corroborated the numerous beneficial activities of fucoxanthin, such as its antioxidant, anti-inflammatory, anticancer or neuroprotective effects, among others. These properties have attracted the attention of nutraceutical, cosmetic and pharmacological industries, giving rise to various possible applications. Fucoxanthin may be chemically produced, but the extraction from natural sources is considered more cost-effective, efficient and eco-friendly. Thus, identifying suitable sources of this compound and giving a general overview of efficient extraction, quantification, purification and stabilization studies is of great importance for the future production and commercialization of fucoxanthin. The scientific research showed that most of the studies are performed using conventional techniques, but non-conventional techniques begin to gain popularity in the recovery of this compound. High Performance Liquid Chromatography (HPLC), Nuclear Magnetic Resonance (NMR) and spectroscopy techniques have been employed in the quantification and identification of fucoxanthin. The further purification of extracts has been mainly accomplished using purification columns. Finally, the stability of fucoxanthin has been assessed as a free molecule, in an emulsion, or encapsulated to identify the variables that might affect its further industrial application.

Visualization and Minima Finding of Multidimensional Hypersurface

Analysis of multidimensional function properties is required for industrial applications. The solution of its problems is a challenge in economics, sociology, chemistry, biology, biochemistry, and other sciences. For example, the study of the potential energy surface (PES) of a free molecule is of fundamental importance in structural chemistry because it is necessary to determine the stable conformations of a molecule and the ways of interconversion between them. However, if the PES is a function of more than three rotational coordinates, the costs of its quantum-chemical calculation rapidly increases and the problem of its graphical visualization can be hardly solved for a large number of variables. This work describes how a specially developed multidimensional interpolation procedure can contribute to solve these problems. To visualize a five dimensional (5D) hypersurface, the authors applied a special coordinate system.

Sulfur-anchored azulene as a cathode material for Li–S batteries

A benzene-free and vinyl-free molecule, azulene, is used to polymerize with sulfur for new cathode material based Li–S batteries.

Normal coordinate analises of (CH3)3PO as free molecule and in complexes with MCl5 (Sb, Nb e Ta)

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Thermophoresis of Nanoparticles in Dilute Gases

The thermophoresis of nanoparticles in the free molecule regime plays an important role in the nucleation, collision and coagulation of nanoparticles. In this contribution, on the basis of a rigorous gas kinetic theory, the theoretical expressions for the thermophoretic force on nanoparticles suspended in dilute gas mixtures are derived, wherein the non-rigid-body interactions between the gas molecules and the nanoparticle are taken into account. The analytical formulas in the present work are consistent with those under the rigid-body collision assumption. Negative thermophoresis, is found to be possible for nanoparticles in the free molecule regime, by which the thermophoretic force exerted on the suspended nanoparticle is from low to high temperature, i.e., opposite to the direction of normal thermophoresis.