Texturation of model clay materials using tape casting and freezing

The present work aimed to investigate the processing of textural clay based materials using tape casting together with freezing. Two model raw materials were used, namely: BIP kaolin from France and ABM montmorillonite from Mediterranean region. The mixtures of both clays were studied, whereby, the amount of montmorillonite was 0, 5, 10, 20 or 50 mass%. After tape casting, the as-obtained green bands were frozen into liquid nitrogen, lyophilized and then fired at 1050 °C or 1200 °C.The amount of montmorillonite appeared as a critical parameter that controls the cohesion of the dry products. For montmorillonite content ≥20 mass%, the products exhibited multiple cracks after lyophilisation. With lower montmorillonite content, the cohesion of the dry products was satisfactorily and a macroscopic cross-linked surface texturation was observed. After calcination at 1050 °C or 1200 °C, the texturation appeared well defined. Moreover, calcination at 1200 °C increased the densification of products and the occurrence of a glassy phase was noted.The combination of both tape casting and freezing (freeze tape casting) is a promising way to develop various clay-based and composites materials exhibiting unique microstructure organization and characteristics with potential application in the field sustainable and environmentally friendly filtration, adsorption or catalysis.     

A new analytical and dynamical model of a scroll compressor with experimental validation

This paper deals with the scroll compressor, which is a machine used for compressing air or refrigerant. By using a novel reference frame, it proposes an original way of describing the geometry of the scroll wraps (represented as circle involutes) in which the symmetries are exploited in order to establish a thermodynamic model of the scroll compressor. This approach allows the chamber volumes to be analytically described without any special assumption and takes into account the discharge as a non-symmetrical process.The proposed geometric model is aimed to be coupled with the thermodynamic model by using the standardized VHDL-AMS language and should be then considered as preliminary to the scroll overall simulation and design of a functional virtual prototype.Simulations and experiments have shown good agreement.     

Prediction of Macrosegregation in Steel Ingots: Influence of the Motion and the Morphology of Equiaxed Grains

Although a significant amount of work has already been devoted to the prediction of macrosegregation in steel ingots, most models considered the solid phase as fixed. As a result, it was not possible to correctly predict the macrosegregation in the center of the product. It is generally suspected that the motion of the equiaxed grains is responsible for this macrosegregation. A multiphase and multiscale model that describes the evolution of the morphology of the equiaxed crystals and their motion is presented. The model was used to simulate the solidification of a 3.3-ton steel ingot. Computations that take into account the motion of dendritic and globular grains and computations with a fixed solid phase were performed, and the solidification and macrosegregation formation due to the grain motion and flow of interdendritic liquid were analyzed. The predicted macrosegregation patterns are compared to the experimental results. Most important, it is demonstrated that it is essential to consider the grain morphology, in order to properly model the influence of grain motion on macrosegregation. Further, due to increased computing power, the presented computations could be performed using finer computational grids than was possible in previous studies; this made possible the prediction of mesosegregations, notably A segregates. This article is based on a presentation given at the International Symposium on Liquid Metal Processing and Casting (LMPC 2007), which occurred in September 2007 in Nancy, France.     

铅在氧化铝微粒上吸附的扫描电镜观察

通过使用含醋酸-磷酸配位体溶液与否进行了两种溶液的实验对微量金属Pb在A l2O3微粒上的结合进行了研究.根据溶液中的化学反应平衡常数的平衡计算,可以显示每种溶液中相应的pH值时会生成Pb的各种可溶性复合物和Pb的沉淀物.借助扫描电子显微镜(SEM)及其必要的辅助手段X线光谱微量分析技术在微观水平上很好地观察并区分重金属Pb在A l2O3微粒表面上是以复合物形式吸附还是以氢氧化物沉淀形式存在这一有趣现象.在电镜下,Pb的复合物[Pb(CH3COO)2]、[Pb(CH3COO)+]、[PbHPO4]和[PbH2PO4+]在A l2O3微粒表面上的吸附显示为许多界限不清的弥漫明亮区.而Pb在A l2O3微粒表面上所形成的PbO沉淀则显示为许多近似环形的界限清楚的明亮区.     

A Complete Separation of Hexane Isomers by a Functionalized Flexible Metal Organic Framework

The separation ability of branched alkane isomers (nHEX, 3MP, 22DMB) of the flexible and functionalized microporous iron(III) dicarboxylate MIL‐53(Fe)‐(CF₃)₂ solid is evaluated through a combination of breakthrough experiments (binary or ternary mixtures), adsorption isotherms, X‐ray diffraction temperature analysis, quasi‐elastic neutron scattering measurements and molecular dynamics simulations. A kinetically controlled molecular sieve separation between the di‐branched isomer of hexane 22DMB from a mixture of paraffins is achieved. The reported total separation between mono‐ and di‐branched alkanes which was neither predicted nor observed so far in any class of porous solids is spectacular and paves the way towards a potential unprecedented upgrading of the RON of gasoline.     

Multimodal person discovery in broadcast TV: lessons learned from MediaEval 2015

Multimedia Tools and Applications - We describe the “Multimodal Person Discovery in Broadcast TV” task of MediaEval 2015 benchmarking initiative. Participants were asked to return the...     

Phenolic composition,antiproliferative and antiulcerogenic activities of a polyphenol-rich purified extract from açai (Euterpe oleracea) fruits

The bioactivity and phytochemical composition of a partially purified extract of açai (PPEA), concentrated in phenolic compounds (PC) and without the presence of macronutrients, were investigated. The major PC quantified by UHPLC-DAD-LTQ-Orbitrap MS-MS/MS in the PPEA are anthocyanins. In vitro, PPEA showed a cytostatic effect on the K-562 lymphoid leukaemia at a concentration of 40 μg PC mL⁻¹, with a GI₅₀ equal to 1.08 μg PC mL⁻¹. In vivo, the extract did not promote acute toxicity in mice in any of the doses tested. The extract displayed gastroprotective activity in rats treated orally with 16, 48 and 160 mg PC kg⁻¹, with a significant decrease in the ulcerative lesion index, compared with the negative control. The lack of toxicity and the bioactivity of the PPEA show that this extract is beneficial to health and useful as a commercial food additive containing natural violet colourant, with pharmaceutical and functional potentials.     

Construction of a stable vehicular ad hoc network based on hybrid genetic algorithm

Telecommunication Systems - In vehicular ad hoc networks, the vehicle speed can exceed 120 kmph. Therefore, any node can enter or leave the network within a very short time. This mobility adversely...     

Experimental study of a liquid film flowing over a perforation

Perforations are one of the recognized geometrical features that contribute to liquid redistribution in corrugated sheet packings. Our experimental study focuses on a simplified but relevant configuration: a thin liquid film flowing on either side of a vertical plate with a circular perforation. We focus on the curtain mode when the liquid fills the perforation. Confocal chromatic imaging reveals a capillary ridge upstream of the perforation, an inertial ridge downstream, and a varicose capillary wave standing on the liquid curtain. We show that the wavelength is selected such that the velocity of the wave both satisfies Taylor's dispersion relation and matches the curtain local speed. We examine the effect of perforation size, supply conditions, and liquid properties on the curtain transition. Lastly, we propose a simple model based on a momentum balance that describes the effect of these parameters on the Reynolds number at which curtain forms.     

Variability of geotechnical parameters of lateritic gravels overlying contrasted metamorphic rocks in a tropical humid area (Cameroon): implications for road construction

Bulletin of Engineering Geology and the Environment - The variability of the geotechnical properties of lateritic gravels developed on metamorphic rocks from the same clay protolith and of a nearby...