The role of microstructural instability on creep behavior of a martensitic 9Cr-2W steel

The microstructural instability during creep and its effect on creep behavior were investigated for a martensitic 9Cr-2W steel. The steel was developed as a low radioactive steel suitable for fusion reactor structure. Creep testing was carried out at 873 K for up to 15,100 ks (4200 hours). The creep curve consisted of transition creep, where creep rate decreased with time, and acceleration creep, where creep rate increased with time. During creep, microstructural instability, such as the recovery of dislocations, the agglomeration of carbides, and the growth of martensite lath subgrains, was observed to occur, which resulted in softening but no hardening. The transition creep was a consequence of the movement and annihilation of excess dislocations, resulting in the decrease in dislocation density and the increase in martensite lath size with time. The acceleration creep was a consequence of a gradual loss of creep strength due to the microstructural instability which occurred from the initial stage of creep.     

Fabrication of amorphous bulk and multi-phase ceramics by melting method in the HfO2-Al2O3-Gd2O3-Eu2O3system

Ceramics have generally been fabricated from powders by shape forming & sintering methods except for glasses and glass ceramics. Glasses and glass ceramics can be fabricated by melting methods. The melting method has not only higher productivity but also higher shape forming ability than powder processes via forming & sintering methods. Thus we have reinvestigated melting methods in binary and ternary oxides systems to fabricate amorphous bulk ceramics and bulk nano composites. We have successfully fabricated amorphous phases by simple melt solidification methods in ternary eutectic melts in the HfO₂-Al₂O₃-Gd₂O₃system. The present study demonstrates the formation of the amorphous phases in quaternary systems HfO₂-Al₂O₃-Gd₂O₃-Eu₂O₃. Furthermore, we have also succeeded to fabricate nano-structured bulk ceramics, which consisted of constituent oxide grains with 20–100 nm in size, by post annealing of the amorphous phase.     

Thermal diffusivity of liquids determined by flash heating of a three-layered cell

An investigation of the applicability of the flash heating of a three-layered cell for determining the thermal diffusivity of a central liquid layer at temperatures between its melting and boiling points is described. Two different cell designs were developed. In one, the outside layers were brazed to a ring-shaped central spacer; in the other, bolted flanges held the outside layers against a central spacer. Test units were fabricated from type 304 stainless steel. Thermal diffusivity results for water obtained with two brazed cells and one bolted cell were all within ±1% of standard reference values. Results obtained with a high temperature salt (Hitec) with two brazed cells were within ±2.5% of each other over the temperature range of 149–427°C. In contrast, bolted cell measurements were inconsistent.     

Preparation and surface active properties of alcohol ethoxylates with an amide oxime terminal group

Amide oxime compounds have become of major interest because they can complex with uranium, gallium and various transition metal ions. In this work surface active amide oximes were prepared to make some functions of the amide oxime group exhibit as molecular aggregates in aqueous media. Amide oximes were obtained from nitriles which were prepared by the cyanoethylation of alcohol ethoxylates with a monodispersed oligo(oxyethylene) group. Surface active properties of these compounds were measured under various conditions and were compared with nonionics of the alcohol ethoxylate type. The pKa₁ values of these amide oximes were about five, and they acted as cationic surfactants under acidic conditions and nonionic ones under neutral and basic conditions. When they served as nonionics, the cloud point, CMC, γ_CMC and foaming properties of surface active amide oximes were similar to other alcohol ethoxylate nonionics.     

Thickness scaling limitation factors of ONO interpoly dielectricfor nonvolatile memory devices

This paper describes the scaling limitation factors of ONO interpoly dielectric thickness, mainly considering the charge retention capability and threshold voltage stability for nonvolatile memory cell transistors with a stacked-gate structure, based on experimental results. For good intrinsic charge retention capability, either the top- or bottom-oxide thickness should be greater than around 6 nm. On the other hand, a thicker top oxide structure is preferable to minimize degradation due to defects. It has been confirmed that a 3.2 nm bottom-oxide shows detectable threshold voltage instability, but 4 nm does not. Effective oxide thickness scaling down to around 13 nm should be possible for flash memory devices with a quarter-micron design rule     

Cortisol and catecholamine kinetics during continuous hemodiafiltration in patients with multiple organ dysfunction syndrome

OBJECTIVE: To assess the influence of continuous hemodiafiltration (CHDF) on cortisol and catecholamine kinetics in multiple organ dysfunction syndrome. DESIGN: Consecutive clinical study. SETTING: General intensive care unit of a university hospital. PATIENTS: Ten adult patients with multiple organ dysfunction syndrome requiring CHDF. MEASUREMENTS AND RESULTS: A total of 40 samples were collected during CHDF for cortisol and catecholamine assays. The clearances for cortisol, epinephrine, norepinephrine and dopamine were 2.5 +/- 1.7 ml/min, 26.3 +/- 2.7 ml/min, 16.7 +/- 4.2 ml/min and 26.3 +/- 2.6 ml/min (Mean +/_ SE), and their daily extractions were 1.8 +/- 0.2 mg/day, 11.4 +/- 4.8 micrograms/day, 1.0 +/- 0.1 micrograms and 2.3 +/- 0.3 micrograms/day, respectively. There were no significant changes in blood cortisol and catecholamine levels during CHDF conducted for 48 h. CONCLUSIONS: The cortisol and catecholamine losses during CHDF were small and unlikely to lead to hemodynamic disturbances.     

Regional differences in the Na+ reabsorption of sweat glands

The author analyzed the presentation of Slovak medical journals in the Medline information system and compared the situation with other countries. Out of all medical magazines issued within the Slovak Republic Medline excerpts only the Bratislava Medical Journal and Neoplasma. The quantitative presentation of medical studies in periodic publications from the Slovak Republic is very favourable in Medline. (Tab. 3, Ref. 9.)     

Transient Characteristics of Thermal Conduction in Dispersed Composites

The effective thermal conductivity of dispersed composites with a hot-melt-adhesive matrix, measured using the steady-state method, is compared with the apparent thermal conductivity calculated from the average heat capacity and from the thermal diffusivity measured by the laser-flash method. The transient effect has been observed obviously at higher volume percentages for various dispersed particle sizes and ratios of the thermal conductivity values of dispersed and continuous phases. All of the experimental results are compared with those calculated by existing models and by the finite element method (FEM). An attempt has been made to show how the criterion for the homogeneity of dispersed composites under transient conditions is affected by the percentages of dispersed phase, dispersed particle size, and ratio of the thermal conductivity values of dispersed and continuous phases.