Electrical conductivity measurement and thermogravimetric study of pure and niobium-doped uranium dioxide

The electrical conductivity and nonstoichiometric composition of UO_2+x and (U_1?yNb_y)O_2+x (y = 0.01, 0.05 and 0.10) were measured in the range $\text{1282 ≦ T ≦ 1373}$ K and Pa by tie four inserted wires method and thermogravimetry, respectively. The electrical conductivity of (U_1?yNb_y)O_2+x plotted against the oxygen partial pressure indicated a minimum corresponding to the transition between $\text{n}$- and $\text{p-}\text{type}$ cone uction. The band-gap energy of (U_1?yNb_y)O_2+x was calculated to be $\text{(248 ± 12)}$ kJmol.^?1, independent of niobium content, which is nearly the same as that of UO_2+x. From the oxygen partial pressure dependences of both the electrical conductivity and the deviation $\text{x}$ of UO_2+x and (U_1?yNb_y)O_2+x, the defect structures in these oxides were discussed with the complex defect model consisting of oxygen vacancies and two kinds of interstitial oxygens.     

Variations in anatomy and ultraviolet microspectrometry between normal and brown midrib mutant maizes possessing different rumen degradabilities

Normal and brown midrib mutant (bmr) maize (Zea mays L) were examined for variations in their morphological composition. The degradability of the leaf blade, leaf sheath and stem, proportional area of specific tissues in leaf blade, and the ultraviolet (UV) absorption spectra of cell walls were measured and related to variations in cell wall degradability by rumen microorganisms. The UV and infrared (IR) absorption spectra of the lignins isolated from leaf blades of both types, before and after reduction with sodium borohydride, were recorded. The bmr3 maize had higher dry matter (DM) and neutral detergent fibre (NDF) degradabilities for leaf blade, leaf sheath, and stem than the normal counterpart. Approximately 35% and 26% of the observed difference in DM degradability was attributed to the difference in DM degradability of stem and leaf blade, respectively, and 39% to the difference in DM composition of stem. Distinct differences in tissue degradation of the leaf blades were observed for mesophyll cell walls in the midrib portion, which were thinner and of greater number in the bmr3 maize. Sclerenchyma cells were present only in the vascular bundles in the bmr3 leaf blade, while in the normal type those cells were underneath the epidermis tissue. The bmr3 plant also had large epidermal cells. UV microspectrometry of mesophyll cell walls of the bmr3 maize showed their lower UV absorbance around 320 nm compared to that of the normal, but not at 280 nm. Considerable increase in the UV absorbance at 280 nm was observed for the isolated lignins after reduction, suggesting a lesser degree of lignification in the bmr3 maize tissues. Lowered UV absorbance of the isolated lignin around 320 nm after reduction was associated with the removal of the IR bands at 1730, 1660, 1600, and 1250 cm^?1.     

Effect of crystalline properties on coercive force in iron acicular fine particles

Crystallographic properties and their size dependence in acicular fine particles of iron prepared by reduction from-FeOOH were investigated by transmission electron microscopy and compared with magnetic properties. Although both larger particles with an average needle length of 0.5m and smaller ones of 0.2m length have single domain configuration, the former are crystal lographicaIly polycrystalline while the latter are single crystal with a [100] axial orientation, an easy magnetization direction of iron. The coercive force, principally yielded by external shape anisotropy, is higher in smaller particles in spite of their inferior axial ratio. The intrinsic magnetocrystalline anisotropy is inferred to be the most responsible to give rise to this further increase of coercive force. The experimentally obtained values of magnetic properties are also compared with the theoretical estimation, which results semi-quantitatively in good accordance.     

Structural plan similarity based on refinements in the space of partial plans

Plan similarity measures play a key role in many areas of artificial intelligence, such as case‐based planning, plan recognition, ambient intelligence, or digital storytelling. In this paper, we present 2 novel structural similarity measures to compare plans based on a search process in the space of partial plans. Partial plans are compact representations of sets of plans with some common structure and can be organized in a lattice so that the most general partial plans are above the most specific ones. To compute our similarity measures, we traverse this space of partial plans from the most general to the most specific using successive refinements. Our first similarity measure is designed for propositional plan formalisms, and the second is designed for classical planning formalisms (including variables and types). We also introduce 2 novel refinement operators used to traverse the space of plans: an ideal downward refinement operator for propositional partial plans and a finite and complete downward refinement operator for classical partial plans. Finally, we evaluate our similarity measures in the context of a nearest neighbor classifier using 2 datasets commonly used in the plan recognition literature (Linux and Monroe), showing good results in both synthetic and real data.     

(Z,Z)-5,27-Tritriacontadiene: Major sex pheromone ofDrosophila pallidosa (Diptera; Drosophilidae)

A crude cuticular extract from both sexes of 3660 fruit flies (Drosophila pallidosa) was subjected to SiO₂ and AgNO₃/SiO₂ column chromatography, accompanied by bioassay for the sex pheromone activity. After three chromatographic steps, the active fraction was obtained. The main component of the active fraction was determined to be (Z,Z)-5,27-tritriacontadiene [(Z,Z)-5,27-C_33:2, on the basis of gas-liquid chromatographic analysis, chemical derivatization and gas chromatography-mass spectrometry. Synthetic (Z,Z)-5,27-C_33:2 at 5 female equivalents (FE) elicited a clear courtship response with a high courtship index amongD. pallidosa males. Therefore it was concluded that (Z,Z)-5,27-C_33:2 was a major sex pheromone component in this species.     

Polymers from 2,5-difluoroterephthalic acid II. Poly(arylene ether)s containing pendant benzoyl groups

Poly(arylene ether)s (9) containing pendant benzoyl groups were prepared by the aromatic substitution reaction of 2,5-difluoro-4-benzoylbenzophenone (7) with bisphenol (8) in the presence of potassium carbonate in N,N-dimethylacetamide. The polycondensation proceeded smoothly at 170°C and produced the desired poly(arylene ether)s with inherent viscosities up to 0.79 dl/g. The polymers were quite soluble in common organic solvents and can be processed into uniform films from solutions. The thermogravimetry of the polymers showed excellent thermal stability, 10% weight losses above 450°C in nitrogen atmosphere. The glass-transition temperatures of the polymers were 138–158°C.     

Studies of refractory carbides,nitrides, and borides as the thermionic emitters for electron microscopy

Thermionic emission properties of several kinds of refractory carbides, nitrides, and borides of the transition metals in the form of powder were investigated with a newly developed measuring device and evaluated by the figure of merit defined as the ratio of the effective work function to the working temperature at which the vapor pressure becomes 1 × 10^?5 Torr. There are several materials whose thermionic emission properties are better than those of tungsten or compatible to those of tungsten among the carbides and borides, such as TaC, HfC, ZrC, LaB₆, and CeB₆, as judged by the figure of merit. New preparation methods for carburization, nitriding, and boriding of the wires of matrix metals and alloys were successfully developed for using these materials as the cathode of the electron microscope. Other necessary techniques such as spot welding and electrolytic etching were also developed. From the brightness characteristics, it was found that some of carbides, carbide solid solutions, and borides such as HfC, ZrC (Ta_0.8–0.7Hf_0.2–0.3)C, TaB₂, and HfB₂ are very good emitters comparable to LaB₆. It is emphasized that the work functions of the carbide-solid solutions (Ta_0.8Hf_0.2)C and (Ta_0.7Hf_0.3)C, which have low rates of evaporation at high temperature, show no remarkable rise as compared with that of HfC, so that their figures of merit are better than that of HfC. Feasibility of providing good cathodes with HfC and (Ta_0.8Hf_0.2)C tips was demonstrated by taking high-resolution electron micrographs.     

Investigation of high-pressure micro jet technology as an alternative to diamond disc conditioning in ILD CMP

The efficacy of an alternative to conventional diamond conditioning in chemical mechanical planarization (CMP) was evaluated in this study. The high pressure micro jet (HPMJ) system sprays ultra-pure water (UPW) at pressures ranging from 10 to 20 MPa onto a CMP pad to clean the pad of slurry residue, remove embedded slurry particles, and re-establish pad asperities. The system is employed in an ex situ fashion and is compared to in situ and ex situ diamond conditioning as well as using no conditioning. Real-time frictional force acquisition allows for coefficient of friction (COF) analysis, which indicates the extent of pad wear. Removal rate analysis, SEM imagery, and pad surface profilometry are also used to evaluate HPMJ as an alternative conditioning technology. Removal rates significantly lower than those associated with diamond conditioning are obtained for the HPMJ system when UPW conditioning is directly followed by polishing. SEM imagery and pad profilimetry indicate these low HPMJ removal rates are due to differences in pad surface chemistry, not pad surface topography. Experiments including a 30 s silicon wafer polish with slurry following HPMJ conditioning to re-establish pad surface chemistry were performed and result in removal rates that are comparable to those obtained using ex situ conditioning. The removal rates obtained using HPMJ conditioning for relative wafer-platen velocities of 0.31 and 0.62 m/s are 8 and 1% higher than those obtained using ex situ diamond conditioning and 18% lower than those obtained using ex situ diamond conditioning for 0.93 m/s. The average COF values for HPMJ conditioning using the intermediate silicon wafer polishes are 15% lower than average COF values associated with ex situ diamond conditioning, suggesting a possible increase in pad life for the HPMJ system.     

Transient shift of local oxygen potential in nonstoichiometric oxides upon application of mechanical stress

Effect of mechanical stress on defect equilibrium was studied with an oxygen nonstoichiometric compound, La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ . In general, formation of oxygen vacancy in an oxide causes lattice expansion, which leads to stabilization of oxygen vacancy in the material under a tensile stress, and vice versa. Oxygen vacancy concentration is thus expected to increase under a tensile stress and decrease under a compressive stress. However, the change in defect concentration would not proceed spontaneously so that the material just after the application of stress would stay out of equilibrium. On this assumption, attempts were made to detect the shift of oxygen potential under stress using a potentiometric method. A ball-shaped yttria stabilized zirconia (YSZ) of 9.5 mm in diameter was utilized as an oxygen potential sensor as well as a pushing rod which was pressed onto the sample surface. In the measurements at 873 K to 1073 K, a clear shift of emf to the negative direction was observed depending on the magnitude of load and loading speed. It was followed by a relaxation to the initial value under the stress. On unloading operation, the shift of emf to the positive direction was observed. Those behaviors were well explained by the assumption that the oxygen vacancy concentration varies under mechanical stress.