Search results for "engineering.material"
showing 10 items of 2352 documents
Effects of Plastic Mulching and Basal Nitrogen Application Depth on Nitrogen Use Efficiency and Yield in Maize
2018
The demand for increased grain production to support population and consumption growth has led to increased interest in field management approaches that incorporate plastic mulching and fertilization management. The purpose of this study was to investigate the effects of plastic mulching and basal nitrogen (N)-fertilizer application depth on N balance estimations, N use efficiency (NUE) and maize yield. The experiment was conducted in 2014 and 2015 with six treatments: no N fertilizer and no mulching (CK), traditional broadcast N fertilizer with mulching (T0), basal N-fertilizer application at a depth of 6 cm with no mulching (T1), basal N-fertilizer application at a depth of 6 cm with plas…
Vertical root fracture in endodontically treated teeth: A review of 25 cases
2001
Abstract Objective: We sought to examine the clinical conditions under which 25 endodontically treated teeth underwent vertical root fracture (VRF) and to relate this condition to the time elapsed from endodontic treatment to fracture. Study Design: This was a retrospective study in which we reviewed 25 case histories of patients with postendodontic VRF and studied the effect of various pretreatment and posttreatment factors as they related to VRF. Results And Conclusions: The mean time to VRF was 54 months; this was not significantly influenced by the presence or absence of prior restoration or by the presence or absence of a crown fitting. The use of a prefabricated, cylindrical, cemented…
A new invariant-based method for building biomechanical behavior laws - Application to an anisotropic hyperelastic material with two fiber families
2013
Abstract In this article, we present a general constructive and original approach that allows us to calculate the invariants associated with an anisotropic hyperelastic material made of two families of collagen fibers. This approach is based on mathematical techniques from the theory of invariants: • Definition of the material symmetry group. • Analytical calculation of a set of generators using the Noether’s theorem. • Analytical calculation of an integrity basis. • Comparison between the proposed invariants and the classical ones.
Portlandite solubility and Ca 2+ activity in presence of gluconate and hexitols
2021
The current paper investigates the impact of gluconate, D-sorbitol, D-mannitol and D-galactitol on calcium speciation at high pH values by i) solubility measurements of portlandite (Ca(OH)2) and ii) potentiometric titration measurements of calcium salt solutions. Thermodynamic modeling was used to fit the chemical activities of Ca2+ and OH- ions and thus to determine the strength and kind of the different Ca-organic-hydroxide complexes. The strength of complex formation with Ca decreases in the order gluconate >> sorbitol > mannitol > galactitol, which follows the same order as sorption on portlandite. Heteropolynuclear gluconate complexes with calcium and hydroxide dominate the…
On the Effect of Surface Treatment to Improve Oxidation Resistance and Conductivity of Metallic Interconnects for SOFC in Operating Conditions
2008
International audience; Due to the reduction of operating temperature from 1000°C to 800°C, chromia forming alloys are the best candidates for interconnects in Solid Oxide Fuel Cells (SOFCs). These interconnects have to be operational in service conditions, at 800°C in air (cathode side) and in humidified hydrogen (anode side). The performance of the interconnect stainless steels is limited by the oxide scale formation (chromia), the low electronic conductivity of this scale and the possible volatility of chromium oxides. In the field of high temperature oxidation of metals, it is well known that the addition of a nanometric layer made of reactive element oxide such as, La2O3, Nd2O3 and Y2O…
Growth of zinc-blende GaN on muscovite mica by molecular beam epitaxy
2021
Abstract The mechanisms of plasma-assisted molecular beam epitaxial growth of GaN on muscovite mica were investigated. Using a battery of techniques, including scanning and transmission electron microscopy, atomic force microscopy, cathodoluminescence, Raman spectroscopy and x-ray diffraction, it was possible to establish that, in spite of the lattice symmetry mismatch, GaN grows in epitaxial relationship with mica, with the [11–20] GaN direction parallel to [010] direction of mica. GaN layers could be easily detached from the substrate via the delamination of the upper layers of the mica itself, discarding the hypothesis of a van der Waals growth mode. Mixture of wurtzite (hexagonal) and z…
Système de prise d'images haute résolution pour l'analyse de projection de particules : application à l'épandage centrifuge d'engrais
2002
This paper describes the design of a high resolution low cost imaging system for the analysis of high speed particle projection. This system, based on a camera and a set of flashes, is used to characterize the centrifugal spreading of fertilizer particles ejected at speeds of environ 30 m s. Multiexposure images collected with the camera installed perpendicular to the output flow of granules are analysed to estimate the trajectories of the fertilizer granules. Very good results are obtained with the Markov random fields method, in comparison with others.
Lead isotopes of the carbonate-hosted Kabwe, Tsumeb, and Kipushi Pb-Zn-CU sulphide deposits in relation to Pan African orogenesis in the Damaran-Lufi…
1999
Lead isotope ratios of galena from the carbonate-hosted massive sulphide deposits of Kabwe (Pb-Zn) and Tsumeb (Pb-Zn-Cu) in Zambia and Namibia, respectively, have been measured and found to be homogeneous and characteristic of upper crustal source rocks. Kabwe galena has average isotope ratios of 206/204Pb = 17.997 ± 0.007, 207/204Pb = 15.713 ± 0.010 and 208/204Pb = 38.410 ± 0.033. Tsumeb galena has slightly higher 206/204Pb (18.112 ± 0.035) and slightly lower 207/204Pb (15.674 ± 0.016) and 208/204Pb (38.276 ± 0.073) ratios than Kabwe galena. The isotopic differences are attributed to local differences in the age and composition of the respective source rocks for Kabwe and Tsumeb. The homog…
Pretreatment of trace element-enriched biomasses grown on phytomanaged soils for bioethanol production
2017
Abstract Phytotechnologies are a set of sustainable, ecological options notably for alleviating pollutant linkages induced by contaminated soils. However, concerns exist regarding the processing of trace elements (TE)-enriched biomass and the fate of TEs in the end-products. The fractionation of phytoremediation TE-enriched non-woody lignocellulosic (tobacco) and woody (birch, willow) phytoremediation-borne biomasses was studied using ethanol organosolv, soda and dilute acid pretreatments. TE distribution in the process fractions (pulp, liquid effluents and lignin) was further examined. In dilute acid conditions, a wood pretreatment performed at 170 °C in the presence of 2% w/w of sulfuric …
Eradication of Plasmodiophora brassicae during composting of wastes
2006
Survival of infectious inoculum of the clubroot pathogen Plasmodiophora brassicae was assessed following bench-scale flask composting experiments and large-scale composting procedures. Clubroot-affected material was provided by artificial inoculation of Chinese cabbage or naturally infected Brussels sprout and cabbage roots. Both sets of diseased material were used in flask experiments, and the latter in large-scale windrow and aerated tunnel experiments. Municipal green wastes, onion waste and spent mushroom compost were evaluated in flask experiments with varying temperature, aeration and moisture conditions. Green wastes were used in larger-scale composts. Within the limits of a Chinese …