State of Utah, by and Through Its Attorney General, Phil L. Hansen v. Salt Lake City, Utah, A Municipal Corporation, by and Through Its Board of Commissioners, Mayor J. Bracken Lee, and Commissioners George B. Catmull, Louis E. Holley, Conrad B. Harrison, and James L. Barker; Its Chief of Police, Dewey Fillis; and/Or Its License Assessor, Thad Emery : Brief of Plaintiff-Respondent

Chevallier Max-Alain. J. Calloud et F. Genuyt, La première épître de Pierre. Analyse sémiotique (Lectio Divina 109), Paris, Editions du Cerf. In: Revue d'histoire et de philosophie religieuses, 63e année n°3, Septembre 1983. pp. 350-351

Band-edge-induced Bragg diffraction in two-dimensional photonic crystals

Two-dimensional photonic crystals composed of two orthogonal volume diffraction gratings have been photogenerated in photopolymers. When the read beam is set at the Bragg angle, the diffraction efficiency of the transmission grating is strongly enhanced at the band edge of the reflection grating recorded in the material. Such a device provides Bragg operation and enhancement of the diffraction efficiency of the thin diffraction grating together with good wavelength selectivity. Such advantages could be interesting for optical signal processing

Hardness and friction behavior of bulk CoAl2O4 and Co–Al2O3 composite layers formed during Spark Plasma Sintering of CoAl2O4 powders

Materials made up of a Co–Al2O3 composite coating over a CoAl2O4 core are prepared during Spark Plasma Sintering of CoAl2O4 powders. The Co particles are precipitated because of a combination of high temperature and low O2 partial pressure. The precipitation and densification processes hamper each other and thus the way the uniaxial pressure is applied during the sintering cycle is an important parameter to control the microstructure of composite layer and its thickness (about 100 mm) and obtain a dense sample (about 4 g/cm3). The friction coefficient of the Co-Al2O3 composites against an Al2O3 ball is lower than that found for an Al2O3 specimen, which could reveal the lubricating role of submicrometer Co particles. However, increasing the load from 5 to 10 N load causes major changes in the friction contact, which are detrimental. Bulk CoAl2O4 was found to have a Vickers microhardness about 15.5 GPa and an average friction coefficient lower than that of an Al2O3 sample

De Walras à Vanek. Coopération et politique

27 pagesAlors que l'idée coopérative était très présente dans les débats politiques jusqu'au début du 20ème siècle, son étude a rapidement été écartée de la science économique, malgré l'intérêt que les pionniers lui ont consacré. Ce n'est qu'au terme d'un processus de dépolitisation (ou de séparation des dimensions économiques et politiques) que l'analyse des coopératives, tour à tour focalisée sur les coopératives de consommateurs, puis d'entreprises puis de travailleurs, est redevenue une thématique présente dans la science économique. La conscience de la dimension politique de l'idée coopérative continue de se renouveler, mais en marge de la science économique

Spark plasma sintering as a reactive sintering tool for the preparation of surface-tailored Fe–FeAl2O4–Al2O3 nanocomposites

Al1.86Fe0.14O3 powders were partially or totally reduced in H2. The fully reduced Fe–Al2O3 nanocomposite powder was sintered by spark plasma sintering (SPS) without any reaction taking place. For the other powders, the SPS induced the formation of FeAl2O4 and sometimes Fe. The most severe reducing conditions were found at the surface of the materials, producing nanocomposites with a surface layer composition and microstructure different to those of the core. This in situ formed composite layer confers a higher hardness and fracture strength

Mechanical and tribological properties of Fe/Cr-FeAl2O4-Al2O3 nano/micro hybrid composites prepared by Spark Plasma Sintering

Fe/Cr–Al2O3 nanocomposite powders are prepared by H2 selective reduction of oxide solid solutions. These powders, an alumina powder and a starting oxide powder, are sintered by spark plasma sintering. The microstructure of the resulting materials is studied. The composites show a lower microhardness and higher fracture strength than unreinforced alumina. The friction coefficient against an alumina ball is lower, revealing the role of the intergranular metal particles, whereas FeAl2O4 grains formed during SPS are beneficial for higher cycle numbers

Influence of pulse current during Spark Plasma Sintering evidenced on reactive alumina–hematite powders

Spark Plasma Sintering (SPS) is increasingly used. The temperature and current are not independent parameters, making it difficult to separate the current intrinsic role from Joule heating. There is a debate on whether there are any specific SPS mechanisms. The influence of a key parameter, the (on:off) pulse pattern, is studied on the SPS of reactive α-Al2−2xFe2xO3 (x = 0.02; 0.05; 0.07; 0.10) powders. Changing it modifies the current crest intensity and has a great influence on the materials microstructure. Comparisons with runs where the current is blocked and hot-pressing reveal three competing phenomena: formation of FeAl2O4, dominant in the core and not peculiar to SPS, formation of Fe, producing Fe-Al2O3 composite surface layers, and most notably electrical-field induced diffusion of Fe3+ ions towards the cathode, which could have far-ranging implications for the consolidation of ionic materials and the in situ reactive shaping of composites and multimaterials

Spark plasma sintering of double-walled carbon nanotubes

Bulk samples of double-walled carbon nanotubes are prepared for the first time. The best spark plasma sintering conditions are (1100 °C, 100 MPa). Raman spectroscopy and scanning electron microscopy show that the nanotubes are undamaged. The density is equal to 1.29 g cm−3 and the pores are all below 6 nm in diameter. The electrical conductivity is equal to 1650 S cm−1. The transverse fracture strength is equal to 47 MPa

Toughened carbon nanotube-iron-mullite composites prepared by spark plasma sintering

Carbon nanotube-iron mullite nanocomposite powders were prepared by a direct method involing a reduction in H2-CH4 and without any mechanical mixing step. The carbon nanotubes are mostly double-andfew-walled (3-6walls). Some carbon nanofibers are also observed. The materials were consolidated by spark plasmas intering. Their electrical conductivity is 2.4S/cm where as pure mullite is insulating. There is no increase in fracture strength, but the SENB toughness is twice than the one for unreinforced mullite(3.3vs.1.6 MPam½). The mechanisms of carbon nanotube bundle pull out and large-scale crack-bridging have been evidenced