Masao Adachi

RESTRICTION FRAGMENT LENGTH POLYMORPHISM OF RIBOSOMAL DNA INTERNAL TRANSCRIBED SPACER AND 5.8S REGIONS IN JAPANESE ALEXANDRIUM SPECIES (DINOPHYCEAE)1

The 5.8S ribosomal RNA (rDNA) gene and flanking internal transcribed spacers (ITS1 and ITS2)from 9 isolates of Alexandrium catenella (Whedon and Kofoid) Taylor, 11 isolates of A. tamarense (Lebour) Taylor, and single isolates of A. affine (Inoue et Fukuyo) Balech, A. insuetum Balech, and A. pseudogonyaulax (Biecheler) Horiguchi ex Yuki et Fukuyo comb. nov. from various locations in Japan were amplified using the polymerase chain reaction (PCR) and subjected to restriction fragment‐length polymorphism (RFLP) analysis. PCR products from all strains were approximately 610 bp, inclusive of a limited region of the 18S and 28S rRNA coding regions. RFLP analysis using four restriction enzymes revealed six distinct classes of rDNA (“ITS types”). Restriction patterns of A. catenella were uniform at the intra‐specific level and clearly distinguishable from those of A. tamarense. The patterns associated with A. tamarense (“tamarense group”) were also uniform except for one strain, WKS‐1. Some restriction fragments from WKS‐1 were in common with those of A. catenella or A. tamarense, whereas some were distinct from all Alexandrium species tested. Alexandrium affine, A. insuetum, and A. pseudogonyaulax carry unique ITS types. The ITSs of the “tamarense group” exhibit sequence heterogeneity. In contrast, the ITSs of all other isolates (including WKS‐1) appear homogeneous. RFLP analysis of the 5.8S rDNA and flanking ITSs regions from Alexandrium species reveals useful taxonomic and genetic markers at the species and/or population levels.

Determination of diffusion coefficient of oxygen in γ-iron from measurements of internal oxidation in Fe-Al alloys

AbstractThe internal oxidation of iron alloys containing between 0.069 and 0.274 wt pct aluminum was investigated in the temperature range from 1223 to 1373 K for the purpose of determining the diffusion coefficients in γ-iron as well as in the internal oxidation layer. A parabolic rate law is obeyed in the internal oxidation of the present alloys. The rate constant for penetration of the oxidation front, the oxide formed, and the concentration of aluminum in the oxidation layer were determined. Pronounced enrichment of aluminum in the oxidation layer was observed, resulting from the counterdiffusion of aluminum. The oxygen concentration at the specimen surface was determined by combining the thermodynamic data on the dissociation of FeO and the solution of oxygen in y-iron. The diffusion coefficient of oxygen in the internal oxidation layer,Do10, was evaluated on the basis of the rate equation for internal oxidation.Do10 increases at a given temperature as the volume fraction of oxide,f10, in the oxidation layer increases. The diffusion coefficient of oxygen in γ-iron,Do, was determined by extrapolation ofDo10 = 0.Do may be expressed as

Internal oxidation of Fe-Al alloys in the α-phase region

D_o = \left( {1.30\begin{array}{*{20}c} { + 0.80} \\ { - 0.50} \\ \end{array} } \right) \times 10^{ - 4} \exp \left[ { - \frac{{166 \pm 5(kJ \cdot mol^{ - 1} )}}{{RT}}} \right]m^2 \cdot s^{ - 1} .

On time optimal control of linear discrete-time systems by geometric approach

Do is close to the diffusion coefficients of carbon and nitrogen in γ-iron.

Minimum time output regulation problem of linear discrete-time systems

The diffusion coefficient of oxygen in α-iron was determined by internal oxidation measurements on iron alloys with various contents of silicon in a temperature range from 1073 to 11 73 K with particular attention to the effect of oxide particles in the oxidation layer. The oxide in the oxidation layer and the concentration of silicon present as an oxide, as well as the rate constant for penetration of the oxidation front were determined. The diffusion coefficient of oxygen in the layer, DO10, calculated using the rate equation for internal oxidation, increases with the increase in volume fraction of the oxide, f10. This result indicates that the existence of oxide particles accelerates oxygen diffusion. Therefore, the diffusion coefficient of oxygen in α-iron is determined by extrapolating DO10to f10 = 0, giving good agreement with results obtained in our recent investigations.

Minimal order of minimal-time deadbeat function observers†

The internal oxidation behavior of Fe-0.069, 0.158, and 0.274 wt% Al alloys was investigated in the α-phase region. The internal oxidation experiments have been made over the temperature range from 1023 to 1123 K using a mixture of iron and its oxide powders. A parabolic rate law holds in the present alloys, where the rate constant, Kp, depends upon the oxidation temperature as well as the aluminum content. The internal oxidation of Fe-Al alloys is, therefore, controlled by a diffusion process of oxygen in the alloy. The oxide formed in the oxidation layer is the stoichiometric FeAl2O4 (hercynite). The aluminum concentration, NAlIo, in the oxidation layer was calculated by taking account of counterdiffusion of aluminum. Furthermore, the oxygen concentration, NOS, at the specimen surface was evaluated on the basis of thermodynamics. Using these estimated values of Kp, NAlIO, and NOS, the diffusion coefficient of oxygen, DOIO, in the oxidation layer, where the oxide particles were dispersed, was also calculated. DOIO increases as the volume fraction of the oxide, fIO, increases. The diffusion coefficient of oxygen, DO, in α-iron was determined by extrapolating DOIO to fIO=0.

Minimum time controllers of linear discrete-time systems

AbstractInternal oxidation measurements of Fe-0.070, 0.219, 0.483, and 0.920 wt % Si alloys were made in the γ-phase region in order to discuss kinetics of internal oxidation, to evaluate the diffusion coefficient of oxygen in the internal oxidation layer, and to determine the diffusion coefficient of oxygen in γ-iron. Internal oxidation of these alloys was conducted at temperatures between 1223 and 1323 K using a powder mixture of iron and Fe2O3. The internal oxidation front in Fe-Si alloys with between 0.070 and 0.483 wt % Si advances in parallel to the specimen surface. The internal oxidation in these alloys obeys a parabolic rate law, which indicates that the internal oxidation is controlled by an oxygen diffusion process in the alloy. The diffusion coefficient of oxygen, DOIO, in the internal oxidation layer where SiO2 particles disperse was determined by using the thermodynamic data for the solution of oxygen in γ-iron. DOIOincreases with the increase of the volume fraction of the oxide, fIO, in the oxidation layer at a given temperature. The diffusion coefficient of oxygen, DO, in γ-iron was evaluated by extrapolating DOIOto fIO=0. DO may be given by the following equation: