Deoxidation of Ti Melt by Newly Developed Two-Step Plasma Arc Melting Process Using Hydrogen

Metallurgical and Materials Transactions B - A two-step plasma arc melting process, comprising a first step under Ar-30 pct H2 gas flow and the second step under Ar gas flow, has been...     

Development of an optimal design aid system based on building information modeling

This study proposes an optimal building design aid system that integrates computer aided design (CAD), building environmental simulation tools and an optimization algorithm, based on the concept of building information modeling (BIM). BIM is a process of generating and managing data during a building’s life cycle. It can be used to demonstrate the entire building’s life cycle, including its construction and operation. Because the design of a build may vary from an abstract shape to precise details, the building’s database should vary accordingly. To store, manage and utilize the building’s data efficiently, we suggest an evolving database structure for our design aid system. A case study verifies that the system can acquire data from CAD, run a number of simulations and generate Pareto solutions automatically during several design stages.     

Structural Analysis of the Complex between Penta-EF-Hand ALG-2 Protein and Sec31A Peptide Reveals a Novel Target Recognition Mechanism of ALG-2

ALG-2, a 22-kDa penta-EF-hand protein, is involved in cell death, signal transduction, membrane trafficking, etc., by interacting with various proteins in mammalian cells in a Ca²⁺-dependent manner. Most known ALG-2-interacting proteins contain proline-rich regions in which either PPYPXnYP (type 1 motif) or PXPGF (type 2 motif) is commonly found. Previous X-ray crystal structural analysis of the complex between ALG-2 and an ALIX peptide revealed that the peptide binds to the two hydrophobic pockets. In the present study, we resolved the crystal structure of the complex between ALG-2 and a peptide of Sec31A (outer shell component of coat complex II, COPII; containing the type 2 motif) and found that the peptide binds to the third hydrophobic pocket (Pocket 3). While amino acid substitution of Phe⁸⁵, a Pocket 3 residue, with Ala abrogated the interaction with Sec31A, it did not affect the interaction with ALIX. On the other hand, amino acid substitution of Tyr¹⁸⁰, a Pocket 1 residue, with Ala caused loss of binding to ALIX, but maintained binding to Sec31A. We conclude that ALG-2 recognizes two types of motifs at different hydrophobic surfaces. Furthermore, based on the results of serial mutational analysis of the ALG-2-binding sites in Sec31A, the type 2 motif was newly defined.     

Optimization of variables in air conditioning control systems: Applications of simulations integrating CFD analysis and response factor method

The integration of three-dimensional spatial distributions into building simulations is of significant interest, and computational fluid dynamics (CFD) analysis is widely employed in building design processes. For example, based on the experience of architects and engineers, CFD analyses are often conducted under steady boundary conditions to determine the degree of attainment of indoor environments. However, CFD analyses have large calculation costs and cannot be often used for simulations with unsteady boundary conditions such as energy simulations in the building design processes. Thus, we developed a method that calculates sensitivities from heat sources to an arbitrary point in an indoor environment and integrates them into simulations with unsteady boundary conditions. In the proposed method, CFD analysis is employed under steady boundary conditions to calculate the response factors, and the resulting sensitivities are integrated into simulations under unsteady boundary conditions. In the present study, the proposed method was applied to optimize the variables of an air conditioning control system. With our method, temperature changes at a sensor over time are calculated from the time series of air supply temperature. In total, 800 calculations were conducted, and the optimal variables that allow the temperature at the sensor to reach the target value quickly were obtained. Except for the time required to calculate the response factors, the optimization in the present study took only a few seconds. If only CFD analysis was used for the optimization, the calculations would take a year. Thus, calculating the sensitivities via CFD analysis and utilizing the results in simulations is a useful approach for solving optimization problems. Moreover, the proposed method is applicable to simulations that require three-dimensional spatial distributions to enhance the accuracy of the calculation such as energy simulations.     

Microstructural Changes During Plastic Deformation and Corrosion Properties of Biomedical Co-20Cr-15W-10Ni Alloy Heat-Treated at 873 K

Metallurgical and Materials Transactions A - Microstructural changes were observed during the plastic deformation of ASTM F90 Co-20Cr-15W-10Ni (mass pct) alloy heat-treated at...     

Thermoelectric properties of ternary and Al-containing quaternary Ru1−xRexSiy chimney–ladder compounds

The thermoelectric properties of ternary and Al-containing quaternary Ru_1?xRe_xSi_y chimney–ladder phases have been studied as a function of the Re concentration with the use of directionally solidified alloys. The Ru_1?xRe_xSi_y chimney–ladder phases exhibit n- and p-type semiconducting behaviors, respectively, at low and high Re concentrations, at which the X(=Si)/M(=Ru + Re) ratios are respectively, larger and smaller than those expected from the VEC (valence electron concentration) = 14 rule. The absolute values of both Seebeck coefficient and electrical resistivity increase as the extent of the deviation from the VEC = 14 rule increases, i.e. as the alloy composition deviates from that corresponding to the p–n transition (x ≈ 0.5), indicating that the carrier concentration can be controlled by changing the extent of compositional deviation from the ideal VEC = 14 composition. The highest values of the dimensionless figure of merit obtained are 0.47 for ternary (x = 0.60) and 0.56 for Al-containing quaternary alloys. The reasons for the systematic compositional deviation from the ideal VEC = 14 compositions observed for a series of chimney–ladder phases are discussed in terms of atomic packing.     

The strength properties of iron aluminides

For the development of Fe−Al alloys as structural materials, a deep understanding of slip and deformation properties is necessary. In particular, since mechanical properties of the iron aluminides are affected by excess vacancy strengthening as well as the positive-temperature dependence of yield stress, controlling these strength features is essential. In this article, the strength properties of iron aluminides are reviewed. Author’s Note: All compositions are provided in mole percent. Kyosuke Yoshimi earned his Ph.D. in materials science and engineering at Tohoku University in 1997. He is currently a research associate at Tohoku University. Shuji Hanada earned his Ph.D. in materials science and engineering at Tohoku University. He is currently a professor at Tohoku University. Dr. Hanada is also a member of TMS.     

Chemical Approach to Biological Safety: Molecular‐Level Control of an Integrated Zinc Finger Nuclease

Application of artificial nucleases (ANs) in genome editing is still hindered by their cytotoxicity related to off‐target cleavages. This problem can be targeted by regulation of the nuclease domain. Here, we provide an experimental survey of computationally designed integrated zinc finger nucleases, constructed by linking the inactivated catalytic centre and the allosteric activator sequence of the colicin E7 nuclease domain to the two opposite termini of a zinc finger array. DNA specificity and metal binding were confirmed by electrophoretic mobility shift assays, synchrotron radiation circular dichroism spectroscopy, and nano‐electrospray ionisation mass spectrometry. In situ intramolecular activation of the nuclease domain was observed, resulting in specific cleavage of DNA with moderate activity. This study represents a new approach to AN design through integrated nucleases consisting of three (regulator, DNA‐binding, and nuclease) units, rather than simple chimera. The optimisation of such ANs could lead to safe gene editing enzymes.     

Real-Time Amplitude and Phase Imaging of Optically Opaque Objects by Combining Full-Field Off-Axis Terahertz Digital Holography with Angular Spectrum Reconstruction

Terahertz digital holography (THz-DH) has the potential to be used for non-destructive inspection of visibly opaque soft materials due to its good immunity to optical scattering and absorption. Although previous research on full-field off-axis THz-DH has usually been performed using Fresnel diffraction reconstruction, its minimum reconstruction distance occasionally prevents a sample from being placed near a THz imager to increase the signal-to-noise ratio in the hologram. In this article, we apply the angular spectrum method (ASM) for wavefront reconstruction in full-filed off-axis THz-DH because ASM is more accurate at short reconstruction distances. We demonstrate real-time phase imaging of a visibly opaque plastic sample with a phase resolution power of λ/49 at a frame rate of 3.5 Hz in addition to real-time amplitude imaging. We also perform digital focusing of the amplitude image for the same object with a depth selectivity of 447 μm. Furthermore, 3D imaging of visibly opaque silicon objects was achieved with a depth precision of 1.7 μm. The demonstrated results indicate the high potential of the proposed method for in-line or in-process non-destructive inspection of soft materials.