Thermodynamics and Phase Equilibria in the Ca─Cu─O System

Phase equilibria in the CaO─CuO─Cu system were determined at 1173 K from the results of X-ray diffraction measurements using specimens annealed in the oxygen partial pressure range from P O₂= 1 to 10⁻⁸ atm. Electromotive force (emf) measurements using ZrO₂ solid electrolyte cells were carried out in the ternary phase equilibria. Gibbs free energies for the chemical reactions were summarized by equations with linear temperature dependence, and the standard free energy of formation for Ca₂CuO₃ was derived. The stability conditions of the oxides are displayed in the p – T – x diagram, and the possible phase equilibria with the liquid are evaluated.     

Phase equilibria in Fe-Cu-X (X: Co, Cr, Si, V) ternary systems

Phase equilibria on the Fe-Cu side in the Fe-Cu-X (X: Co, Cr, Si, V) system were experimentally determined over the temperature range of 1073–1273 K. Based on the present results and previous works, the thermodynamic assessments of the phase equilibria in the Fe-Cu-X system were evaluated using the Calculation of Phase Diagram (CALPHAD) method. The Gibbs energies (G) of the bcc, fcc, and liquid phases are described by the subregular solution model, and a set of thermodynamic parameters enable us to calculate various isothermal and vertical sections and the miscibility gaps of the solid and liquid phases.     

Highly Stretchable,Global, and Distributed Local Strain Sensing Line Using GaInSn Electrodes for Wearable Electronics

For identifying human or finger movement, it is necessary to sense subtle movements at multiple points, including the local strain and global deformation simultaneously; however, this has not yet been realized. Therefore, a highly stretchable, global, and distributed local strain sensing electrode made of GaInSn and polydimethylsiloxane is developed for wearable devices. To investigate the electrical properties of multiple sections of the GaInSn electrode when stretching, tensile, cyclic, and three‐point‐bending tests are performed. The results demonstrate that the electrode can withstand a strain up to 50% and has little hysteresis without any delay. Moreover, the distributed local strain and global strain can be simultaneously measured using just a single electrode line. Finally, a prototype of a data glove as an application of the strain sensing line is manufactured, and it is demonstrated that the folding state of fingers could be identified. The proposed technology may allow the creation of a lightweight master hand manipulator or 3D data entry device.     

GaAs MESFET characterization using least squares approximation byrational functions

The authors propose a method of characterizing active devices such as the FET by describing S-parameters with a set of rational functions of angular frequency. The set of rational functions is uniquely determined by only 27 coefficients, while the conventional method using tabulated S-parameters requires eight times the number of sampling points (a typical case might require 404 data points in floating-point notation). This drastically reduces the database size required to give adequate information for circuit design. A method for determining the equivalent circuit is described. Since the equivalent circuit is determined from the set of rational functions, no additional measurements are needed to determine extrinsic elements. In conventional methods, selection of initial values affects the final results. In the present method, reliable initial values are extracted from the rational functions' coefficients. The calculated S-parameters of three GaAs MESFETs having different gate widths agree closely with those measured by wafer-probe     

Use of Ozone to Prepare Silver Oxides

The possible use of ozone to produce higher oxides was analyzed thermodynamically. Because the activity of oxygen in ozone is ∼10¹⁸ at room temperature and ∼10⁸ at 773 K, ozone may react with metals to yield higher-oxidation-state products than does an ambient pressure of pure oxygen. In agreement with this thermodynamic prediction, silver oxides (AgO and Ag₂O) were synthesized experimentally by blowing a gas mixture of 6 vol% ozone and oxygen through a water-cooled lance. Neither Ag₃O₄ nor Ag₂O₃ was detected. Slow oxygen diffusion into a metal and/or reaction products and decomposition of unstable oxides that are formed successively are obstacles to practical applications of syntheses via ozone oxidation.     

Study of static cushioning properties: Automated data input and reliability test of static cushioning properties

A computer-controlled compression testing machine is used to compile a database of the static cushioning properties of package cushioning materials. Through research into automated data input procedures, so far not developed, a direct transfer program (ZABCON) has been devised, which allows direct access to the disk in which compression test data are stored. Elimination of manual data input has led to simplified and easy construction of a database, and the applied laboratory tests, such as that for determining the relationship between static cushioning properties and compression rate, can be performed quite readily. Also in this report, the application of the static cushioning characteristics of foamed polystyrene in the cushioning package design of dummy goods and the evaluation of its reliability by drop testing are discussed.     

Synthesis of Nanohole‐Structured Single‐Crystalline Platinum Nanosheets Using Surfactant‐Liquid‐Crystals and their Electrochemical Characterization

Nanohole‐structured single‐crystalline Pt nanosheets have been synthesized by the borohydride reduction of Na₂PtCl₆ confined to the lyotropic liquid crystals (LLCs) of polyoxyethylene (20) sorbitan monooleate (Tween 80) with or without nonaethylene‐glycol (C₁₂EO₉). The Pt nanosheets of around 4–10 nm in central thickness and up to 500 nm or above in diameter have a number of hexagonal‐shaped nanoholes ∼1.8 nm wide. High‐resolution electron microscope images of the nanosheets showed atomic fringes with a spacing of 0.22 nm indicating that the nanosheets are crystallographically continuous through the nanoholed and non‐holed areas. The inner‐angle distributions for the hexagonal nanoholes indicate that the six sides of the nanoholes are walled with each two Pt (111), Pt (1 1) and Pt (010) planes. The formation mechanism of nanoholed Pt nanosheets is discussed on the basis of structural and compositional data for the resulting solids and their precursory LLCs, with the aid of similar nanohole growth observed for a Tween 80 free but oleic acid‐incorporated system. It is also demonstrated that the nanoholed Pt nanostructures loaded on carbon exhibit fairly high electrocatalytic activity for oxygen reduction reaction and a high performance as a cathode material for polymer‐electrolyte fuel cells, along with their extremely high thermostability revealed through the effect of electron‐irradiation.     

Interfacial Reaction Between Cu Substrates and Zn-Al Base High-Temperature Pb-Free Solders

Chemical reactions between Cu substrates and Zn-Al high-temperature solder alloys, Zn-4Al and Zn-4Al-1Cu (mass%), at temperatures ranging from 420°C to 530°C were experimentally investigated by a scanning electron microscope using backscattered electrons (SEM-BSE) and an electron probe microanalyzer (EPMA). Intermediate phases (IMPs), β(A2) or β′(B2), γ(D8₂), and ε(A3) phases formed and grew during the soldering and aging treatments. The consumption rate of the IMP for Cu substrates is described by the square root of t in both the alloys, while the additional Cu in the molten Zn-Al alloy slightly suppresses the consumption of Cu substrates. The growth of IMPs during soldering treatment is controlled by the volume diffusion of constituent elements, and its activation energy increases in the order of Q _ε < Q _γ < Q _β. In view of the aging process, the growth of IMPs is considered to be controlled by the volume diffusion. In particular, the layer thickness of γ rapidly grows over 200°C, although the thickness of the β layer grows very slowly.     

CoCl(2) inhibits neural differentiation of retinoic acid-treated embryoid bodies

The effects of CoCl(2) on retinoic acid (RA)-treated embryoid bodies (EBs) were investigated. Four-day EBs were treated with 5x10(-6) M of RA for 4 d, then subjected to attached culturing for 7 d in the presence of CoCl(2) at 0, 20, and 100 microM. Differentiation into MAP2- and GFAP-immunopositive cells was inhibited by CoCl(2) in a dose-dependent manner. Next, RA-treated EBs were dissociated into single cells and cultured for 7 d at an initial cell density of 1x10(3)/cm(2). The number of cells increased in a CoCl(2)-dose dependent fashion. In cultures with 100 microM of CoCl(2), more than 90% of the cells were immunopositive for nestin and nestin-immunopositive cells formed clusters, while there were few cells immunopositive for MAP2 or GFAP. These results suggest that CoCl(2) inhibits neural differentiation of RA-treated EB cells and promotes the proliferation of nestin-immunopositive cells, i.e., embryonic stem (ES)-derived neural stem-like cells.     

Bending fatigue strength of case-carburized helical gears with large helix angles up to 40 degrees

Case-carburizing of helical gears with large helix angles may form too large hardened layers near the tooth width end on the acute angle side (ACUTE-END), and adversely affect the bending fatigue strength. We investigated the bending fatigue strength of casecarburized helical gears with large helix angles up to approximately 40° through a bending fatigue test, hardness test, and residual stress measurement. We found that the case-carburizing formed large hardened layers near ACUTE-END, reduced the compressive residual stress near ACUTE-END, and restricted the improvement of the bending fatigue strength in a meshing state where tooth root stress became large near ACUTE-END. Based on the obtained bending fatigue limits, we revealed that ISO 6336-3:2006 overestimated the rate of increase of the permissible circumferential loads for helix angles exceeding approximately 30°, and ISO/DIS 6336-3:2018 underestimated this rate for helix angles near 30°.