There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

II. Structure of Perovskites 1982 A. Crystal Structure 1982 B. Nonstoichiometry in Perovskites 1983 1. Oxygen Nonstoichiometry 1983 2. Cation Nonstoichiometry 1984 C. Physical Properties 1985 D. Adsorption Properties 1986 1. CO and NO Adsorption 1986 2. Oxygen Adsorption 1987 E. Specific Surface and Porosity 1987 F. Thermal Stability in a Reducing Atmosphere 1989 III. Acid−Base and Redox Properties 1990 A. Acidity and Basicity 1990 B. Redox Processes 1991 1. Kinetics and Mechanisms 1992 2. Reduction−Oxidation Cycles 1993 C. Ion Mobility 1993 1. Oxygen Transport 1993 2. Cation Transport 1994 IV. Heterogeneous Catalysis 1995 A. Oxidation Reactions 1995 1. CO Oxidation 1995 2. Oxidation of Hydrocarbons 1996 B. Pollution Abatement 2001 1. NOx Decomposition 2001 2. Exhaust Treatment 2002 3. Stability 2004 C. Hydrogenation and Hydrogenolysis Reactions 2004 1. Hydrogenation of Carbon Oxides 2004 2. Hydrogenation and Hydrogenolysis Reactions 2006

Chemical structures and performance of perovskite oxides.

This review article aims to provide an updated and comprehensive description of the development of the Electric Current Activated/assisted Sintering technique (ECAS) for the obtainment of dense materials including nanostructured ones. The use of ECAS for pure sintering purposes, when starting from already synthesized powders promoters, and to obtain the desired material by simultaneously performing synthesis and consolidation in one-step is reviewed. Specifically, more than a thousand papers published on this subject during the past decades are taken into account. The experimental procedures, formation mechanisms, characteristics, and functionality of a wide spectrum of dense materials fabricated by ECAS are presented. The influence of the most important operating parameters (i.e. current intensity, temperature, processing time, etc.) on product characteristics and process dynamics is reviewed for a large family of materials including ceramics, intermetallics, metal–ceramic and ceramic–ceramic composites. In this review, systems where synthesis and densification stages occur simultaneously, i.e. a fully dense product is formed immediately after reaction completion, as well as those ones for which a satisfactory densification degree is reached only by maintaining the application of the electric current once the full reaction conversion is obtained, are identified. In addition, emphasis is given to the obtainment of nanostructured dense materials due to their rapid progress and wide applications. Specifically, the effect of mechanical activation by ball milling of starting powders on ECAS process dynamics and product characteristics (i.e. density and microstructure) is analysed. The emerging theme from the large majority of the reviewed investigations is the comparison of ECAS over conventional methods including pressureless sintering, hot pressing, and others. Theoretical analysis pertaining to such technique is also proposed following the last results obtained on this topic.

Consolidation/synthesis of materials by electric current activated/assisted sintering

Application of Fe–16Cr ferritic alloy to interconnector for a solid oxide fuel cell

LaCrO{sub 3} is a p-type semiconductor, and it is stable in both oxidizing and reducing atmospheres at elevated temperatures. LaCrO{sub 3} doped with Ca or Sr exhibits high electrical conductivity. Due to these properties, alkaline earth-doped LaCrO{sub 3} is used as an interconnector for solid oxide fuel cells (SOFC), which are attractive because of their high energy conversion efficiency and clean exhaust gas. Since the interconnector is used at elevated temperatures with a large difference of oxygen pressure between anode and cathode, it is extremely important to clarify its transport properties to understand demixing and creep. In several oxides with the perovskite structure, oxide ion diffusivity has been reported. On the other hand, cation diffusivity, which probably governs the demixing and creep processes, has been scarcely reported. The parabolic rate constant for the solid-state reaction of 1/2La{sub 2}O{sub 3} + 1/2Cr{sub 2}O{sub 3} = LaCrO{sub 3} was measured at temperatures between 1,483 and 1,688 /K in air and at 1695 K in oxygen pressures between 2.1 {times} 10{sup 4} and 1.5 {times} 10{sup {minus}5} Pa.

Solid-state reaction kinetics of LaCrO3 from the oxides and determination of La3+ diffusion coefficient

https://www.jstage.jst.go.jp/article/jinstmet1952/63/7/63_7_917/_pdf

Neck Growth on Initial Stage of Pulse Current Pressure Sintering for Coarse Atomized Powder Made of Cast-Iron

http://iopscience.iop.org/article/10.1016/j.stam.2004.11.004/pdf

High-temperature oxidation of ceramic matrix composites dispersed with metallic particles

High temperature steam oxidation of the commercial Fe–9mass%Cr–026mass%Si steel (ASME T91) was carried out at 973 K, and the formation and disappearance of an IOZ (Internal Oxidation Zone) is discussed based on the microstructure observation by OM, and TEM with EDS The IOZ formed at the initial stage and disappeared within about 100 ks Sample oxidized for 612 ks showed a continuous IOZ, and TEM observation at the alloy/IOZ interface clarified that a sheet-like amorphous SiO2 layer formed intermittently On the sample oxidized for 6264 ks, the IOZ had disappeared and a sheet of amorphous SiO2 was located at the alloy/inner scale interface The inner scale progressively grew next to the SiO2 layer due to an increase of oxygen potential at the interface because of the extremely low oxygen permeability in the amorphous SiO2

Makoto Nanko

Papers

Application of Fe–16Cr ferritic alloy to interconnector for a solid oxide fuel cell

Solid-state reaction kinetics of LaCrO3 from the oxides and determination of La3+ diffusion coefficient

Neck Growth on Initial Stage of Pulse Current Pressure Sintering for Coarse Atomized Powder Made of Cast-Iron

High-temperature oxidation of ceramic matrix composites dispersed with metallic particles

Formation and disappearance of an internal oxidation zone in the initial stage of the steam oxidation of Fe–9Cr–0.26Si ferritic steel