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Latter Material (latter + material)
Selected AbstractsGraphite Oxides Obtained from Porous Graphite: The Role of Surface Chemistry and Texture in Ammonia Retention at Ambient ConditionsADVANCED FUNCTIONAL MATERIALS, Issue 10 2010Mykola Seredych Abstract Graphite oxides (GO) synthesized using Brodie and Hummers methods are tested for ammonia adsorption at ambient conditions with different contents of water in the system. Surface characterization before and after exposure to ammonia is performed using XRD, FTIR spectroscopy, potentiometric titration, thermal analysis, adsorption of nitrogen, and XPS. Oxidation of the same porous graphite using two methods results in materials with different textural and chemical features. On GO obtained using the Brodie method mainly epoxy and carboxylic groups are present whereas on the GO obtained using the Hummers method chemisorbed oxygen is also found. The contribution of the carboxylic groups in the latter material is greater. It also contains sulfur either in sulfones or as residual sulfuric acid. Ammonia is adsorbed either via reaction with surface groups or dissolution in water. The former is responsible for strong adsorption. The evidence of the catalytic effect of the carbon surface on activation of oxygen leading to surface oxidation is also observed. [source] Access of autonomic nerves through the optic canal, and their orbital distribution in manTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2003Gordon L. Ruskell Abstract The notion that autonomic nerves from the internal carotid plexus are transmitted to the orbit with the ophthalmic artery through the optic canal has been variously assumed, disregarded, or denied, but never demonstrated. The objective of this study was to examine the contents of the canal, identify any autonomic nerves, and follow their passage within the orbit. The soft tissues of the optic canal, and the apical tissues of the orbit were removed and examined histologically using 10 cadaver preparations. Additionally, tissues from an orbital exenteration and 10 ocular enucleation or donor specimens were prepared. Some of the latter material was examined with an electron microscope. Numerous autonomic nerves (four to 25, ranging in diameter from 23 to 130 ,m) entered the orbit from the internal carotid plexus in the periosteum of the optic canal, the optic nerve dura mater, or the adventitia of the ophthalmic artery. In the orbit they advanced in the loose connective tissue covering the optic nerve dura and joined ciliary nerves close to the eye or entered the eye directly. None were observed to penetrate the dura, apart from a nerve accompanying the central retinal artery. Others were distributed with the ophthalmic artery and its branches. It is concluded that the optic canal is a regular, and often major, route for autonomic nerve distribution to the eye and orbit. Anat Rec Part A 275A:973,978, 2003. © 2003 Wiley-Liss, Inc. [source] High-Temperature Oxidation at 1900°C of ZrB2,xSiC Ultrahigh-Temperature Ceramic CompositesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2008Wen-Bo Han Oxidation of ZrB2 -based ultrahigh-temperature ceramic composites containing 10, 20, and 30 vol% SiC was performed at 1900°C for 1 h in air. ZrB2,20 vol% SiC exhibited the highest oxidation resistance at this temperature and formed a dense coherent oxide scale after oxidation, whereas a strong degradation was observed for both ZrB2,10 vol% SiC and ZrB2,30 vol% SiC. In addition, cracks and spallation in the oxide scale were also detected for the latter materials. The oxidation behaviors of ZrB2,SiC composites were investigated. The effect of SiC content was analyzed and oxidation models were proposed to describe the observed microstructures. [source] Processing and Mechanical Behavior of CrN/ZrO2(2Y) CompositesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2000Yoshihiko Takano CrN powder consisting of granular particles of ,3 ,m has been prepared by self-propagating high-temperature synthesis under a nitrogen pressure of 12 MPa using Cr metal. Dense pure CrN ceramics and CrN/ZrO2(2Y) composites in the CrN-rich region have been fabricated by hot isostatic pressing for 2 h at 1300°C and 196 MPa. The former ceramics have a fracture toughness (KIC) of 3.3 MPa ·m1/2 and a bending strength (,b) of 400 MPa. In the latter materials almost all of the ZrO2(2Y) grains (0.36,0.41 ,m) are located in the grain boundaries of CrN (,4.6 ,m). The values of KIC (6.1 MPa · m1/2) and ,b (1070 MPa) are obtained in the composites containing 50 vol% ZrO2(2Y). [source] | ||||||||||