Formation of NbC and TaC by solid-state reaction

The formation of NbC and TaC by solid-state reaction of Nb₂O₅ and Ta₂O₅ with carbon, respectively, was studied at 1000 to 1285° C by X-ray diffraction. Factors affecting the formation of the carbides, such as the nature of the reaction vessel, the molar ratio of carbon/oxide, the form of reactant carbon, etc., were examined. By covering the graphite crucible and increasing the molar ratio of carbon to oxide, complete formation of NbC and TaC could be achieved in about 60 min at low temperatures (1170 and 1225° C, respectively). The beneficial effect of covering the crucible is ascribed to the retention of CO which facilitates the reaction at low temperatures. The formation kinetics of NbC and TaC obey a first-order equation, with activation energies of 90 and 93 kcal mol^–1, respectively. Possible mechanisms for the solid-state reactions are discussed.     

Preparation of Fe-N films by r.f. sputtering

Fe-N films over a wide compositional range have been prepared by the reactive sputtering method. Fe-N sputtered films were composed of a single or two phases such as-Fe₂N,-Fe_3.02N,-Fe_3.82N,-Fe₄N and-Fe; however, an unknown phase was observed at a higher nitrogen pressure. A remarkable preferred orientation of the-Fe_3.02N (110) plane parallel to the film surface was observed. The Curie temperature of the sputtered -Fe_3.82N sample was 490° C, which was almost the same as that of-Fe₄N prepared by metal nitriding. The saturation magnetization, _s, of the sputtered Fe-N samples decreased from 151.8 to 42.4 e.m.u.g^–1 with increasing nitrogen content from 7.94 to 24.87 at%, and its coercive force,₁ H _c was found to lie in the range 150 to 600 Oe in the powder form at room temperature.     

Grain-Oriented Ca3Co4O9 Thermoelectric Oxide Ceramics Prepared by Solid-State Reaction

We studied a method to enhance the degree of grain orientation of Ca₃Co₄O₉ thermoelectric oxide ceramics. Ceramic specimens were prepared by solid-state reaction with different growth conditions. Large-grained Ca₃Co₄O₉ powders were obtained by using “heavy-calcination” and “moderate-grinding” steps before pelletizing, and these large-grained powders contributed to the enhancement of the degree of orientation. Scanning electron microscopy (SEM) observation results showed that plate-like crystal grains were stacked up in layers for the heavily calcined ceramics, while no such anisotropic structure was found for those that were lightly calcined. x-Ray diffraction (XRD) analysis also indicated that the specimen obtained by heavy-calcination and moderate-grinding steps had a high degree of (002) orientation. The effect of the heavy-calcination and moderate-grinding steps was clearly evidenced by the electrical resistivity ρ. The electrical resistivity ρ at 700°C for the higher-oriented ceramics was 73% of that for the lower-oriented ceramics. Since ρ was reduced without deterioration of the Seebeck coefficient S, the power factor (S ²/ρ) at 700°C for the former was increased by 29% compared with that for the latter.     

Molecular reorientation behavior of photocrosslinkable liquid-crystalline polymer films containing phenylamide side chains

The cooperative molecular reorientation in methacrylate copolymer films comprising photoreactive 4-(4-methoxycinnamoyloxy)biphenyl and phenylamide in their side chains was investigated by irradiation with linearly polarized ultraviolet light and subsequent annealing. Both cinnamate and phenylamide side groups were miscible in the copolymer composition, and axis-selective photoreaction of the cinnamate groups was observed. Thermally enhanced cooperative in-plane orientation of both side groups was obtained when the irradiated films were annealed in the liquid-crystalline temperature range of the copolymers.     

KRAS/BRAF Analysis in Ovarian Low-Grade Serous Carcinoma Having Synchronous All Pathological Precursor Regions

Ovarian low-grade serous carcinoma is thought to begin as a serous cystadenoma or adenofibroma that progresses in a slow stepwise fashion. Among the low-grade serous carcinomas, there is a high frequency of activating mutations in the KRAS or BRAF genes; however, it remains unclear as to how these mutations contribute to tumor progression. This is the first report to track the histopathological progression of serous adenofibroma to low-grade serous carcinoma. Each stage was individually analyzed by pathological and molecular genetic methods to determine what differences occur between the distinct stages of progression.     

Autophagy and Autophagy-Related Diseases: A Review

Autophagy refers to the process involving the decomposition of intracellular components via lysosomes. Autophagy plays an important role in maintaining and regulating cell homeostasis by degrading intracellular components and providing degradation products to cells. In vivo, autophagy has been shown to be involved in the starvation response, intracellular quality control, early development, and cell differentiation. Recent studies have revealed that autophagy dysfunction is implicated in neurodegenerative diseases and tumorigenesis. In addition to the discovery of certain disease-causing autophagy-related mutations and elucidation of the pathogenesis of conditions resulting from the abnormal degradation of selective autophagy substrates, the activation of autophagy is essential for prolonging life and suppressing aging. This article provides a comprehensive review of the role of autophagy in health, physiological function, and autophagy-related disease.     

Effect of High‐Pressure Oxygen Annealing on Electrical and Magnetoelectric Properties of BaSrCo2Fe11AlO22 Ceramics

The effect of high‐pressure oxygen (HPO) annealing on the electrical, magnetic, and magnetoelectric (ME) properties of room‐temperature multiferroic BaSrCo₂Fe₁₁AlO₂₂ ceramics was investigated. The electrical resistivity of the ceramics was found to strongly depend on the partial oxygen pressure during annealing at 1040°C. Samples annealed under ~10 atm of oxygen exhibited a resistivity of up to 1.6 × 10⁹ Ω·cm at room temperature, more than two orders of magnitude higher than that of samples without oxygen annealing. Thermally stimulated current and complex impedance measurements suggested that the enhancement of the resistivity by the HPO annealing originated from a decrease in the amount of defects related to oxygen vacancies and an increase in the resistance of grains and interfaces. HPO annealing also affects the magnetic‐field response of spiral magnetic ordering, which is ascribed to the ME properties. Furthermore, samples subjected to HPO annealing exhibited a lower contribution of the space charges trapped at the grain boundaries and/or defects to the magnitude of the measured magnetoelectrically induced electric polarization P. The present results indicate that HPO annealing is an effective method to evaluate authentic ME effects in multiferroic BaSrCo₂Fe₁₁AlO₂₂ ceramics.     

Hydrophilicity transition of the clean rutile TiO2 (1 1 0) surface

We present contact angle measurements of water on single-crystal rutile TiO₂ (1 1 0) surfaces, exposed to ambient air, or protected in dry air. Our measurements indicate that the surfaces exposed to ambient air are hydrophobic, with a contact angle of θ = 61(5)°. However, the well-protected dry surface also exhibits some hydrophobic tendency, with θ = 32(5)°. It is known that UV irradiation transforms both surfaces superhydrophilic, with θ = 0° [R. Wang, K. Hashimoto, A. Fujishima, M. Chikuni, E. Kojima, A. Kitamura, M. Shimohigoshi, T. Watanabe, Nature 388 (1997) 431-432]. We also present preliminary X-ray crystal truncation rod measurements on the hydrophobic TiO₂ (1 1 0) surface, and of the effect of UV illumination on the surface.     

Friction anchor welding between Al alloy and Zn-coated steel using insert steel difference in the mechanism of friction anchor welding between the types of Zn coatings on Zn-coated steel

The lap joints of upper Al alloy sheets (1.0-mm-thick A5052) and lower Zn-coated steel sheets (1.2-mm-thick GI steel or GA steel) were welded using insert steel sheets (0.6-mm-thick SPCC) by a spot welding process with a tool having a spherical ceramic tip, i.e. ‘Friction Anchor Welding.’ As a result, straight (not-rugged) steel projections were formed in the Al alloy sheets for both the GI and GA, while steel projections were not formed for the GI, rugged steel projections were formed for the GA without the insert steel sheets. In addition, the tensile shear strength for the GI was greater than that for the GA. In other words, the tensile shear strengths reached about 3.9 kN/point for the GI and about 3.2 kN/point for the GA, which were greater than those of the welds without the insert steel sheets. On the other hand, the cross tensile strengths for the GI and GA were almost the same, which reached about 2.6 kN/point. Additionally, for the GI, the Zn layer on the GI steel sheet melted and was totally removed due to the pressure and heat caused by the rotating tool, which facilitated the welding between the SPCC and GI steel sheets. For the GA, however, the Zn-Fe layer on the GA steel sheet changed to a solid-liquid mixture and was not completely removed, which prevented the welding between the SPCC and GA steel sheets. Therefore, the thickness of the steel-steel welded region (i.e. the SPCC-GI or the SPCC-GA welded region) for the GI was greater than that for the GA. We estimated that the difference in this thickness is significantly related to the fracture mechanism during the tensile shear test and the cross tensile test.     

Partial hydrothermal oxidation of unsaturated high molecular weight carboxylic acids for enhancing the cold flow properties of biodiesel fuel

Biodiesel fuel has become more attractive recently because of its environmental benefits and the fact that it is a product made from renewable resources. However the less favorable cold flow properties or the low temperature operability of biodiesel fuel compared to conventional diesel is a major drawback limiting its use. The poor flow properties of biodiesel at cold temperatures are mainly due to biodiesel fuel being composed of long-chain fatty acids with an alcohol molecule attached. If the double bond of unsaturated fatty acids in these long-chain fatty acids could be ruptured selectively, then the cold flow properties of biodiesel fuel would be enhanced by reducing its viscosity.In this study, the selective hydrothermal oxidation of oleic acid, as a model compound of unsaturated high molecular weight carboxylic acids, was studied experimentally. The objective was to use this as a model to investigate whether the double bond of unsaturated fatty acids can be ruptured selectively by partial hydrothermal oxidation. Demonstration of this method could then be used to show the potential to improve the cold flow properties of biodiesel. Results showed that the amount of mono-carboxylic acids, aldehyde, di-carboxylic acids, and aldehyde-acids with a carbon number of 9 was significantly higher than other oxidative products. This suggests that the oxidative cleavage may principally occur at the double bond in hydrothermal conditions. The cloud and pour points for biodiesel fuel (B100) and B100 blend with a mixture of methyl esters or acetals were measured. These are the most important indicators for the cold flow properties of biodiesel fuel. The methyl esters or acetals used were made from the esterification of carboxylic acids or aldehydes by simulating the major oxidation products. These were obtained from the hydrothermal oxidation of oleic acid at different oxygen supply rates. Results showed that the cloud and pour points of the blend were significantly enhanced compared to those of B100.