CO2 sensing properties of semiconducting copper oxide and spinel ferrite nanocomposite thin film

A new active layer for CO2 sensing based on semiconducting CuO–CuxFe3−xO4 (with 0 ≤ x ≤ 1) nanocomposite was prepared by radiofrequency sputtering from a delafossite CuFeO2 target using a specific in situ reduction method followed by post annealing treatment in air. The tenorite–spinel ferrite nanocomposite layer was deposited on a simplified test device and the response in a carbon dioxide atmosphere was measured by varying the concentration up to 5000 ppm, at different working temperatures (130–475 °C) and frequencies (0.5–250 kHz). The results showed a high response of 50% (Rair/RCO2=1.9) at 250 °C and 700 Hz for a CO2 concentration of 5000 ppm

Microstructure, porosity and roughness of RF sputtered oxide thin films: Characterization and modelization

Spinel CoMnFeO4 thin films are stable materials useful to study the influence of radio-frequency (RF) sputtering experimental conditions on the microstructure of oxide films. It has been demonstrated by various techniques such as electronic and atomic force microscopy (AFM), gas adsorption techniques and ellipsometry, that films prepared with 0.5 Pa sputtering argon pressure and 5 cm target–substrate distance are very dense. On the other hand, the samples obtained under higher pressure and/or longer distances are microporous with a mean pore size generally lower than 2 nm. The specific surface areas of such films reach about 75 m2/g. According to the simple model proposed, the films are made of three layers. From the bottom to the top of the film, the first one at the interface with the substrate is 100% dense. The second layer is made of cylindrical rods set up according to a compact plane. Its porosity is due to the lattice interstices. Hemispheric domes covering each rod make up the third layer, which displays a degree of roughness related to the shape and the hexagonal arrangement of the domes. The surface enhancement factor (SEF), the porosity and roughness, calculated from the model, are in corroboration with the experimental values. The porosity factor is however slightly underestimated by the model for very porous samples

Abcès encéphaliques: prise en charge, à propos d’une série de 82 cas

Les auteurs proposent des options thérapeutiques dans la prise en charge des abcès encéphaliques, en fonction des paramètres cliniques et radiologiques des patients, en dégageant des facteurs pronostiques à long terme. Il s'agit d'une étude rétrospective incluant tous les abcès encéphaliques pris en charge, sur une période 13 ans, au service de Neurochirurgie de l'Hôpital Ibn Sina de Rabat. L'analyse a porté sur : le Glasgow coma scale (GCS), la présence de déficit neurologique, l'imagerie cérébrale avec contraste, et la recherche d'une porte d'entrée; le traitement a compris chirurgie et antibiothérapie, et le pronostic a été évalué à long terme. 82 cas d'abcès ont été analysés, un score de GCS inférieur à 12 a été trouvé dans 24%. La porte d'entrée a été d'origine ORL dans 45%. La trépanoponction seule a été décidée dans 34% des cas en situation d'urgence avec troubles de conscience. Elle a été suivie d'une exérèse de la coque dans 16% des cas lors de persistance ou récidive de la collection. La ponction stéréotaxiques a été réalisée dans 10% des cas lors de localisations éloquentes et l'exérèse d'emblée dans 38% des cas avec abcès collecté non menaçant. La mortalité  opératoire a été de 1,22%, la morbidité de 19,30%. Les facteurs de bon pronostic à long terme ont été l'âge jeune, un GCS supérieur à 12 à l'admission, et la trépanoponction suivie de l'exérèse da la coque.  L'amélioration du pronostic passe par le diagnostic précoce, un geste neurochirurgical précis et antibiothérapie adaptée, et le traitement des portes d'entrée.Key words: abcès,cerveau,chirurgie, antibiothérapie, prise en charg

Effects of Lizardite Addition on Technological Properties of Forsterite-monticellite Rich Ceramics Prepared from Natural Magnesite and Dolomite

Lizardite rich peridotite has never been used to prepare ceramic specimens, especially in Morocco. For this raison, potential use of naturally abundant lazirditic material from the Rif domain, as a supply for ceramic industry, has been evaluated. The effects of lizardite addition to magnesite and dolomite mixtures on the thermomechanical properties of the calcined ceramics were also detailed. To achieve this target, natural lizardite, magnesite and dolomite samples were collected in ultrabasic Beni Bousra massif. Those raw samples were used for the synthesis of a forsterite-monticellite rich ceramics. Both raw and sintered samples were characterized by x-ray diffraction, scanning electron microscope and fourier transform infrared. The obtained results showed that both magnesite and dolomite were mainly composed of MgCO3 and CaCO3. In contrast, lizardite sample showed high amounts of SiO2, MgO and Fe2O3. An increased amount of lizardite in the initial mixtures enhanced mechanical and dimensional properties of the prepared ceramic specimens, and subsequently, the production of ceramics with the required technological properties. Thus, the preparation of Moroccan lizardite-based ceramics is technically feasible, economically justifiable and socially desirable due to the contribution to the economic growth of the raw materials sector, especially ceramic industry

Couches minces d'oxydes spinelles et de nanocomposites spinelle-CuO à propriétés semi-conductrices destinées à la réalisation de capteurs de gaz

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Synthesis and CO Gas-Sensing Properties of CuO and Spinel Ferrite Nanocomposite Thin Films

A nanocomposite thin film composed of tenorite (CuO) and spinel ferrite (CuxFe3−xO45 has been prepared by radio-frequency sputtering method followed by a post-deposition thermal annealing. The nanostructure was examined by grazing X-ray diffraction, atomic force microscopy and scanning electron microscopy. CuO-CuxFe3−xO4 nanocomposite layer was deposited on the top of screenprinted gold electrodes onto SiO2(200 nm)/Si substrate. It was found that this material contains p–n nano-heterojunctions, was sensitive to 500 ppm carbon monoxide at the operational temperature of 400 °C and exhibited a large response of 90%

Potential valorisation of steel slag waste as an alternative material for pavement layers

Cilj ovog rada istražiti izvedivost korištenja otpadne čelične zgure kao zamjenskog materijala za slojeve kolničke konstrukcije (nosive slojeve). Ovaj se otpad skladišti i odlaže na odlagalište na lokaciji za proizvodnju čelika u JORF LASFAR-u, u gradu El Jadida, Maroko. Prikupljeni su uzorci otpada koji su podvrgnuti standardnim ispitivanjima kako bi se utvrdila njihova fizikalna, kemijska, mineraloška i geotehnička svojstva. Nadalje, otpadna čelična zgura ne može se koristiti samostalno u slojevima kolničke konstrukcije zbog niskog udjela sitnog agregata. Prirodni materijal (otpad od drobljenja kamena) upotrijebljen je s otpadnom čeličnom zgurom kako bi se postigla zahtijevana granulometrijska krivulja. Napravljeno je ukupno pet različitih mješavina čelične zgure (SS) i prirodnog agregata (ST) u sljedećim omjerima (% SS: % ST): M1 (30:70), M2 (40:60), M3 (50:50), M4 (60:40), i M5 (70:30). Provedena su geotehnička i mehanička ispitivanja svake pojedinačne mješavine, uključujući i mješavine M4 i M5, kako bi se utvrdilo ispunjavaju li te mješavine uvjete da bi se koristile u gornjim nosivim slojevima. Mješavine oznaka od M2 do M5 također su imale svojstva koja su potrebna za materijal donjih nosivih slojeva. Na kraju je provedena analiza dimenzioniranja kolničke konstrukcije kako bi se dobila debljina slojeva koji sadrže formulirane mješavine, za koje je utvrđeno da su slične debljinama konvencionalnih materijala.This paper aims to investigate the feasibility of using steel slag waste as an alternative material for pavement layers (sub-base and base layers). This waste is stored and landfilled at a steel production site in JORF LASFAR, city of El Jadida, Morocco. Samples of the waste were collected and underwent standard tests to determine its physical, chemical, mineralogical, and geotechnical properties. Furthermore, the steel slag waste cannot be used alone in pavement layers because of the low fraction of fine aggregates. Additionally, a sterile raw material (rock crushing waste) was used with the steel slag waste to obtain the required particle size distribution. Five mixtures of steel slag (SS) and sterile (ST) were formulated using the following proportions (% SS: % ST): M1 (30:70), M2 (40:60), M3 (50:50), M4 (60:40), and M5 (70:30). Geotechnical and mechanical standard tests were conducted on each mixture, including the M4 and M5 mixtures, to determine whether they met the required properties for a material used in the base layer. M2 to M5 mixtures also had the necessary properties for the sub-base layer. Finally, a sizing study was performed to obtain the thickness of pavement layers containing the formulated mixtures, which were found to be close to those of conventional materials