Selection of thinner for epoxy–amine system used as binder for polymeric mortars

Epoxy resin mortars are mainly used in the implementation of precast items used in the civil engineering field. The workability of these mortars represents a major obstacle to the development of this field. In order to improve this property, different types of thinners are selected to study their effect on the rheological properties of the epoxy–amine system. Rheological tests are performed in order to estimate the resin gel point and to measure its viscosity during the crosslinking reaction. It appears that viscosity is the lowest for mixtures prepared with methyl octanoate, o‐xylene, and butyl glycidyl ether. Methyl octanoate is chosen as an ecofriendly thinner. The curing process is evaluated by varying the amount of the selected thinner using isothermal and dynamic DSC to determine the end of crosslinking. The mechanical properties using dynamic mechanical analysis (DMA) and tensile resistance testing of the cured epoxy resin with different amounts of methyl octanoate are also investigated. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43970.     

Formation of Cobalt Phyllosilicate During Solid State Preparation of Co2+/ZSM5 Catalysts from Cobalt Acetate

When CO²⁺/ZSM5 catalysts are prepared by solid state exchange between H-ZSM5 and cobalt acetate, CO²⁺ ions form layered cobalt phyllosilicate at the surface of the zeolite grains, bringing about a reassessment of the chemistry involved in the preparation of catalytic systems by solid state exchange.     

Investigations on the leaf anatomy and ultrastructure of grapevine (Vitis vinifera) under heat stress

Leaf anatomical and ultrastructural responses of "Razegui" and "Muscat Italia" grapevine cultivars to high temperatures were studied under controlled conditions (T > 36°C), based on photonic and electron microscopy. Histological studies performed on leaves from heat-stressed and control grapevines revealed thicker leaf blades under high temperature conditions. Environmental scanning electron microscopy of leaf surfaces from both cultivars allowed observing sinuate epidermal cells on the leaves of grapevines cultivated under heat stress and irregular giant oblong pores on their adaxial surface. When observed by transmission electron microscopy, leaf cross sections in grapevines cultivated under high temperature conditions exhibited folded cuticle and cell wall on the adaxial epidermis layer. Therefore, significantly greater cell wall thicknesses were measured under heat stress than control conditions in both cultivars. Regarding chloroplasts, they were more globular in shape under heat stress compared with control conditions and had disorganized thylakoids with a reduced thickness of grana stacking. The size of starch granule decreased, while the number of plastoglobules increased with heat stress, indicating a reduced carbon metabolism and a beginning of senescence within the 3-month heat stress period. This study confirms widespread adaptive properties in two grapevine cultivars in response to high temperature stress.     

Characterization and reactivity of aerogel sulfated zirconia-ceria catalyst for n-hexane isomerization

Sulfated zirconia doped with cerium has been prepared by sol gel process using the supercritical evacuation way of the solvent. The physicochemical and catalytic properties of aerogel solids AZC were compared as a function of both the Ce/Zr molar ratio and the calcination temperature. The samples were characterized by N₂ adsorption desorption, XRD, FTIR, RAMAN, XPS spectroscopy and TPD of NH₃. The catalyst prepared with molar ratio Ce/Zr = 0.4 exhibits the high activity and selectivity toward isomerization product in the n-hexane isomerization reaction. This result is probably due to its important total acidity.     

Investigations on the leaf surface ultrastructure in grapevine (Vitis vinifera L.) by scanning microscopy

Several Scanning microscopy techniques were used to investigate the leaf surface ultrastructure in the local “Razegui” grapevine cultivar (Vitis vinifera L.). Conventional scanning electron microscopy performed on glutaraldehyde‐fixed samples allowed observation of well‐preserved epidermal cells with an overlaying waxy layer. At a high magnification, the waxy layer exhibited crystalline projections in the form of horizontal and vertical platelets. Also, to avoid eventual ultrastructural alterations inherent in the use of solvents during sample preparation, fresh leaf blade samples were directly observed by environmental scanning electron microscopy. A classical image of convex living epidermal cells was observed. At 2400× magnification, epicuticular waxes exhibited a granular structure. However, high‐magnification images were not obtained with this device. The atomic force microscopy (AFM) performed on fresh leaf blade samples allowed observation of a textured surface and heterogeneous profiles attributed to epicuticular wax deposits. AFM topography images confirmed further, the presence of irregular crystalloid wax projections as multishaped platelets on the adaxial surface of grapevine leaf. SCANNING 31: 127–131, 2009. © 2009 Wiley Periodicals, Inc.     

Optimization of a supply portfolio in the context of supply chain risk management: literature review

The aim of this paper is to review the literature in the field of supplier selection under supply chain risk management. Collected papers from 2003 to 2014 are analyzed and classified, first, according to the characteristics of the problem they deal with, secondly, according to the approach they propose, and thirdly, according to the techniques they use. The papers have been grouped into five categories: the first group relates to quantitative approaches to supplier selection, the second concerns qualitative approaches, the third consists of hybrid approaches that blend two or more different approaches together, the fourth relates to simulation approaches and the last group to artificial intelligence. The techniques used in each category are outlined. The different approaches and their associated techniques are analyzed and some recommendations are made on improving their efficiency and performance. This paper is thus a systematic scope review of journal articles and conference papers issued during this period. It brings together a collection of 124 papers on the topic of supplier selection under supply chain risk management.     

Reconstruction 3D robuste du visage: approche duale « mouvement-structure »

An original approach for three-dimensional reconstruction and animation of human face with a monocular and un-calibrated acquisition system is presented. This method is based on the classical analysis-synthesis scheme. A three-dimensional reconstruction of shape and movement is performed with a combination of two algorithms using the well-known “Zfrom motion” principle. Therefore a pre-processing step is needed to first detect the human face on vidéoconférence sequence. Then, a set of points is tracked with a new hybrid and adaptive block-matching algorithm using the Delaunay tessellation. A local algebraic projective invariant family performs the 3D movement classification to satisfy the 3D synthesis assumptions. Experimental results on synthetic and noisy data set validate the entire approach.     

Numerical investigations of the heating distribution effect on the boiling flow in bubble pumps

Numerical simulations of the heating repartition effect on the boiling flow in vertical tube are performed using the commercial CFD (Computational Fluid Dynamics) package FLUENT. The Eulerian multiphase flow framework model was applied to describe the phase interactions. User-Defined Functions (UDFs) are provided to compute the wall heat transfer and the inter-phase heat and mass transfer. Two different configurations of the bubble pump are considered: Total and partial heating of the pump tube.