Relationships between seismic design conditions and superior design solutions of steel buildings

The Japanese version of this paper was published in volume 87, number 802, pages 1257–1266, https://doi.org/10.3130/aijs.87.1257, of the Journal of Structural and Construction Engineering (Transactions of AIJ). The authors have obtained permission from the editor of the Journal of Structural and Construction Engineering (Transactions of AIJ) for secondary publication of the English version in another journal. This paper is a translation of the original Japanese version with slight modifications and corrections.Superior design solutions (SDSs) of seven-story steel buildings are obtained for the space frame system (SFS) and the perimeter frame system (PFS) in various types of structures such as moment frames (MF) and those with buckling restrained braces (BRBF). The SDSs satisfy the design constraints of allowable stress design (ASD) and calculations of resistance and limit state (CRLS) with minimized steel volume. The influences of design conditions are comparatively evaluated. It is found that the maximum inter-story drift ratio for the safety limit in the CRLS for MF can be rationally defined as 2% and ASD can be more dominant for BRBF

Hybrid anode design of polymer electrolyte membrane water electrolysis cells for ultra-high current density operation with low platinum group metal loading

Reducing platinum group metal (PGM) loading and high current density operation are both essential for minimizing the capital expenditure (CAPEX) of polymer electrolyte membrane (PEM) electrolyzers. Catalyst-integrated porous transport electrodes (PTEs) in which iridium acts as both a catalyst and a conductive coating on porous transport layer (PTL) surfaces, enable the preparation of Pt-coating-free PTLs, but can also result in relatively high activation and ohmic overvoltages. Here, a novel hybrid anode design combining an intermediate catalyst layer and a catalyst-integrated PTE is developed. This hybrid anode demonstrates that Ir on PTL can contribute to the oxygen evolution reaction (OER) and exhibits comparable electrolysis performance to a conventional anode consisting of Pt-coated PTL with the same Ir loadings despite Pt-coating-free on the PTL of the hybrid anode. This novel anode eliminates the need for a Pt coating whilst also enabling ultra-high current density operations up to 20 A cm−2 with a total PGM loading of only around 0.6 mg cm−2 on the anode side. This paper proposes a next-generation anode structure with new functions of PTLs for ultra-high current density operation with low PGM loading to significantly reduce green hydrogen costs

Catalyst-integrated gas diffusion electrodes for polymer electrolyte membrane water electrolysis : porous titanium sheets with nanostructured TiO2 surfaces decorated with Ir electrocatalysts

Novel catalyst-integrated gas diffusion electrodes (GDEs) for polymer electrolyte membrane water electrolysis (PEMWE) cells are presented, in which porous titanium microfiber sheets are etched in NaOH to generate a nanostructured TiO2 surface, followed by arc plasma deposition (APD) of iridium nanoparticles. The porous titanium sheet acts as a gas diffusion layer (GDL); the nanostructured TiO2 surface acts as a catalyst support with large surface area; and the iridium nanoparticles act as the electrocatalyst. The performance of these unique GDEs in PEMWE cells was optimized by etching in different NaOH concentrations to vary the nanostructure of the TiO2; and by varying the Ir loading via the number of APD pulses. The current-voltage characteristics and the durability of the optimized GDEs were comparable to those reported in the literature using conventional Ir-based electrocatalysts, and electrolysis was achieved with current density up to 5 A cm-2. The main advantages of this catalyst-integrated GDE include the very low iridium loading (i.e. around 0.1 mg cm-2, or just one-tenth of the loading typically used in conventional PEMWEs); high electrolysis current density; the fabrication of stacks with fewer components; and the fabrications of thinner stacks. This could ultimately lead to smaller and lower cost PEMWE systems

Ru-core Ir-shell electrocatalysts deposited on a surface-modified Ti-based porous transport layer for polymer electrolyte membrane water electrolysis

Novel Ru-core Ir-shell catalyst-integrated porous transport electrodes (PTEs) for polymer electrolyte membrane water electrolysis (PEMWE) cells are prepared, in which Ru-core Ir-shell catalyst nanostructures are directly deposited onto a porous transport layer (PTL) via arc plasma deposition (APD). The PTL has a nanostructured TiO2 surface prepared via NaOH etching, acting as a catalyst support. The performance and durability of these Ru-core Ir-shell catalysts depend strongly on the ratio of Ir and Ru. The current-voltage (I–V) characteristics of PEMWE cells were improved by applying these core-shell catalysts with a low Ir loading of around 0.1 mg cm−2. The core-shell catalyst-integrated PTEs can operate at current densities of up to 10 A cm−2 without exhibiting limiting current behavior. This unique combination of the core-shell catalyst and the PTE structure enables PEMWE cell operation with low iridium loading and high current density, potentially reducing the cost of green hydrogen

Cold start cycling durability of fuel cell stacks for commercial automotive applications

System durability is crucial for the successful commercialization of polymer electrolyte fuel cells (PEFCs) in fuel cell electric vehicles (FCEVs). Besides conventional electrochemical cycling durability during long-term operation, the effect of operation in cold climates must also be considered. Ice formation during start up in sub-zero conditions may result in damage to the electrocatalyst layer and the polymer electrolyte membrane (PEM). Here, we conduct accelerated cold start cycling tests on prototype fuel cell stacks intended for incorporation into commercial FCEVs. The effect of this on the stack performance is evaluated, the resulting mechanical damage is investigated, and degradation mechanisms are proposed. Overall, only a small voltage drop is observed after the durability tests, only minor damage occurs in the electrocatalyst layer, and no increase in gas crossover is observed. This indicates that these prototype fuel cell stacks successfully meet the cold start durability targets for automotive applications in FCEVs

Accelerated durability testing of fuel cell stacks for commercial automotive applications : a case study

System durability is crucially important for the successful commercialization of fuel cell electric vehicles (FCEVs). Conventional accelerated durability testing protocols employ relatively high voltage to hasten carbon corrosion and/or platinum catalyst degradation. However, high voltages are strictly avoided in commercialized FCEVs such as the Toyota MIRAI to minimize these degradation modes. As such, conventional durability tests are not representative of real-world FCEV driving conditions. Here, modified start-stop and load cycle durability tests are conducted on prototype fuel cell stacks intended for incorporation into commercial FCEVs. Polarization curves are evaluated at beginning of test (BOT) and end of test (EOT), and the degradation mechanisms are elucidated by separating the overvoltages at both 0.2 and 2.2 A cm-2. Using our modified durability protocols with a maximum cell voltage of 0.9 V, the prototype fuel cell stacks easily meet durability targets for automotive applications, corresponding to 15-year operation and 200,000 km driving range. These findings have been applied successfully in the development of new fuel cell systems for FCEVs, in particular the second-generation Toyota MIRAI

A Genome-Wide Association Study Identified AFF1 as a Susceptibility Locus for Systemic Lupus Eyrthematosus in Japanese

Systemic lupus erythematosus (SLE) is an autoimmune disease that causes multiple organ damage. Although recent genome-wide association studies (GWAS) have contributed to discovery of SLE susceptibility genes, few studies has been performed in Asian populations. Here, we report a GWAS for SLE examining 891 SLE cases and 3,384 controls and multi-stage replication studies examining 1,387 SLE cases and 28,564 controls in Japanese subjects. Considering that expression quantitative trait loci (eQTLs) have been implicated in genetic risks for autoimmune diseases, we integrated an eQTL study into the results of the GWAS. We observed enrichments of cis-eQTL positive loci among the known SLE susceptibility loci (30.8%) compared to the genome-wide SNPs (6.9%). In addition, we identified a novel association of a variant in the AF4/FMR2 family, member 1 (AFF1) gene at 4q21 with SLE susceptibility (rs340630; P = 8.3×10−9, odds ratio = 1.21). The risk A allele of rs340630 demonstrated a cis-eQTL effect on the AFF1 transcript with enhanced expression levels (P<0.05). As AFF1 transcripts were prominently expressed in CD4+ and CD19+ peripheral blood lymphocytes, up-regulation of AFF1 may cause the abnormality in these lymphocytes, leading to disease onset

Structural change of ion-induced carbon nanofibers by electron current flow

A graphite foil was irradiated with argon (Ar(+)) ions to fabricate conical structures with a carbon nanofiber (CNF) on top of the structure. The field emission (FE) properties of one-dimensional individual CNF-tipped cones that had been fabricated were carefully measured by in situ transmission electron microscopy (TEM) facilities. The highest FE current, 550 nA, was observed in the current-voltage (I-V) measurement of a single CNF. Almost no degradation in I-V properties were detected during the reliability test after 30 min. TEM images indicated that the CNF was amorphous in nature initially, and that the electron current flow in the FE process induced the dramatic change in the crystalline structure of both the CNF and of the tip region of the basal cone part. After performing the FE process, the crystalline structures of the amorphous CNFs were transformed into ring-shaped graphene layers, whereas nanodiamond like nanoparticles formed in the outer layer of the tip region of the basal cone. The structural changes induced can be attributed to Joule heating under the high electric field

Transparent and flexible field electron emitters based on the conical nanocarbon structures

The fabrication of conical nanocarbon structures (CNCSs) on a transparent and flexible nafion substrate at room temperature using an ion irradiation technique and their application toward field emission displays (FEDs) have been demonstrated. The main advantage of this technique is that CNCSs can be fabricated directly on the transparent substrate while retaining the transparency of the substrate. A scanning electron microscopy (SEM) image revealed that the sputtered surface was entirely covered with CNCSs with a calculated numerical density of 6 × 106 /mm2. Such nafion based CNCSs have proved to be an effective electron emitter with turn-on and threshold fields of 6.1 and 9.5 V/μm, respectively. The field enhancement factor was estimated to be 1020 from the Fowler−Nordheim (F−N) plot. Thus the room temperature fabricated CNCSs based on transparent and flexible nafion substrate would be very promising for future flexible (roll-up) and transparent FED