Optimisation des paramètres d’un filtre à accord numérique dans une large bande de fréquences. Vérification expérimentale vers 300 MHz

This paper gives the method which permits to calculate the parameters of a 2 ^N channels filter with high selectivity: a regular distribution of 2^N channels in a wide band (225–400 MHz) and a digital tuning using switching PINdiodes can be obtained.     

Voltage-Current Characteristics of a Simple Zinc Oxide Varistor Containing Magnesia

This paper examines the effect of MgO addition on the structural and electrical characteristics of a ZnO varistor composition with few dopants. MgO acts as a grain-growth inhibitor. The electrical performances of the obtained varistors are improved.     

Design of Phosphonated Imidazolium-Based Ionic Liquids Grafted on γ-Alumina: Potential Model for Hybrid Membranes

Imidazolium bromide-based ionic liquids bearing phosphonyl groups on the cationic part were synthesized and grafted on γ-alumina (γ-Al₂O₃) powders. These powders were prepared as companion samples of conventional mesoporous γ-alumina membranes, in order to favor a possible transfer of the results to supported membrane materials, which could be used for CO₂ separation applications. Effective grafting was demonstrated using energy dispersive X-ray spectrometry (EDX), N₂ adsorption measurements, fourier transform infrared spectroscopy (FTIR), and special attention was paid to ³¹P and ¹³C solid state nuclear magnetic resonance spectroscopy (NMR).     

Heat transfer and fluid flow of nanofluids in laminar radial flow cooling systems

Nanofluids are considered as interesting alternatives to conventional coolants. It is well known that traditional fluids have limited heat transfer capabilities when compared to common metals. It is therefore quite conceivable that a small amount of extremely fine metallic particles placed in suspension in traditional fluids will considerably increase their heat transfer performances. A numerical investigation into the heat transfer enhancement capabilities of coolants with suspended metallic nanoparticles inside a radial, laminar flow cooling configuration is presented. Temperature dependant nanofluid properties are evaluated from experimental data available in recent literature. Results indicate that considerable heat transfer increases are possible with the use of relatively small volume fractions of nanoparticles. Generally, however, these are accompanied by considerable increases in wall shear-stress. Results also show that predictions obtained with temperature variable nanofluid properties yield greater heat transfer capabilities and lower wall shear stresses when compared to predictions using constant properties.     

Adapting an ultrasonic image threshold method to eddy current images and defining a validation domain of the thresholding method

This paper presents a generalization to eddy current images of a thresholding method developed for ultrasonic imaging. It is also shown how to improve the thresholding strength through the definition of a cooperation rule between two threshold assessment measures. This rule is also used to reduce time of calculus. These measures are calculated from the image cooccurrence matrix. The aim is to build a thresholding method that gives a threshold value but also an indicator which allows the operator to know if the methodology applies to the processed image. Examples of results are presented.     

New phospholipid fatty acids from the marine spongeCinachyrella alloclada uliczka

The fatty acid composition of phospholipids from the Senegalese spongeCinachyrella alloclada was examined. Two new fatty acids not hitherto found in nature, namely 10,13-octadecadienoic acid and 16-tricosenoic acid, were identified. 8-Hexadecenoic, 13-nonadecenoic and 5,9,13-trimethyltretradecanoic fatty acids were also found for the first time in sponges. The latter compound (1.4% of the total fatty acid mixture), an isoprenoid fatty acid, accompanies the major fatty acid 4,8,12-trimethyltridecanoic acid (19.7%). The monomethyl branched fatty acids (22%) identified include 23-methylpentacosanoic acid (anteiso-26∶0), not previously observed in sponged. The major long-chain fatty acids encountered were the known 17-tetracosenoic 19-heptacosadienoic and 5,9,23-tricontatrienoic acid. Some sixty fatty acids were identified as methyl esters andN-acyl pyrrolidides by gas chromatography and gas chromatography/mass spectrometry.     

Mechanical Properties of an Extruded Wood Plastic Composite: Analytical Modeling

Abstract

The focus of this study has been to predict wood plastic composite (WPC) properties using analytical models dedicated to reinforced composites and to define their limits. Experiment tests have been realized to characterize mechanical properties of a commercial WPC. On one hand, good compressive and three points bending performances were observed in agreement with application requirements for this decking product. On the other hand, lower tensile performance and failure appearances revealed a lack of interfacial bonding between wood fiber and matrix despite the presence of a coupling agent in the composite formulation.     

Rapid Discrimination of Neuromyelitis Optica Spectrum Disorder and Multiple Sclerosis Using Machine Learning on Infrared Spectra of Sera

Neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) are both autoimmune inflammatory and demyelinating diseases of the central nervous system. NMOSD is a highly disabling disease and rapid introduction of the appropriate treatment at the acute phase is crucial to prevent sequelae. Specific criteria were established in 2015 and provide keys to distinguish NMOSD and MS. One of the most reliable criteria for NMOSD diagnosis is detection in patient’s serum of an antibody that attacks the water channel aquaporin-4 (AQP-4). Another target in NMOSD is myelin oligodendrocyte glycoprotein (MOG), delineating a new spectrum of diseases called MOG-associated diseases. Lastly, patients with NMOSD can be negative for both AQP-4 and MOG antibodies. At disease onset, NMOSD symptoms are very similar to MS symptoms from a clinical and radiological perspective. Thus, at first episode, given the urgency of starting the anti-inflammatory treatment, there is an unmet need to differentiate NMOSD subtypes from MS. Here, we used Fourier transform infrared spectroscopy in combination with a machine learning algorithm with the aim of distinguishing the infrared signatures of sera of a first episode of NMOSD from those of a first episode of relapsing-remitting MS, as well as from those of healthy subjects and patients with chronic inflammatory demyelinating polyneuropathy. Our results showed that NMOSD patients were distinguished from MS patients and healthy subjects with a sensitivity of 100% and a specificity of 100%. We also discuss the distinction between the different NMOSD serostatuses. The coupling of infrared spectroscopy of sera to machine learning is a promising cost-effective, rapid and reliable differential diagnosis tool capable of helping to gain valuable time in patients’ treatment.