Nippon Steel Chemical and Material (Japan)

More frequent extreme rainfall has heightened the need to understand vegetation’s influence on slope stability in steep terrain. Among vegetation-related factors, root-system overlap, the intersection of neighboring root networks, remains understudied despite its potential to influence shallow landslide processes. Here we present laboratory flume experiments testing whether root overlap modulates slope stabilization, using pea plants (Pisum sativum) at 50 (V-005), 200 (V-02), 400 (V-04), and 1100 (V-11) stems/m2 densities. Landslide initiation was most delayed at V-11, while V-02 and V-005 failed at times comparable to the unvegetated control. V-04 had the smallest landslide area, while lower and higher densities produced larger landslides. Higher plant density increased root reinforcement, yet accelerated soil saturation via preferential flow along overlapping roots. The optimal balance of reinforcement, delaying hydrological triggering, and minimizing landslide size occurred between V-04 and V-11. This study reveals how vegetation density influences slope stability through root-driven geotechnical and hydrological processes. Vegetation density influences slope stability with higher root-system overlaps delaying landslide initiation and smaller landslide areas at moderate densities, according to lab flume experiments using pea plants with different densities.

XAFS分析を用いて，曝露初期に端面鋼素地に形成された腐食生成物中でのMgの存在形態を解析した．その結果，Zn‒11Al‒3Mgめっき鋼板の曝露初期の鋼素地上には，Mgを含有したZn5（OH）8Cl2・H2Oが形成された．また，MgはZn5（OH）8Cl2・H2O中の層間に侵入しているのではなく，Znの2種類の結晶学的サイト両方を一部置換している可能性が高いと考えられる．

The effect of carbon on the heterogeneous deformation behavior of a martensite was investigated by multiscale strain distribution analysis using the digital image correlation method. Specially, 18%Ni martensitic steels with and without carbon (0.15C steel and C-free steel, respectively) were studied. Low-magnification observation showed that in both steels, a macroscopic strain distribution was caused by the shape of the specimen. However, high-magnification observation revealed that the strain was concentrated in specific blocks in 0.15C steel, suggesting that its heterogeneous deformation behavior depends on the martensitic structure. Thus, addition of carbon in 18%Ni steel was concluded to cause preferential plastic deformation of the blocks owing to an in-lath plane slip system, which tends to promote heterogeneous deformation.

Abstract Industrial Cr(VI) effluents pose persistent environmental threats due to their toxicity and non‐biodegradability. This study pioneers a novel functional sludge‐derived biochar (SC@BC) synthesized via co‐pyrolysis of coking sludge (CS, carbon source) and cold‐rolling oily sludge (CROS, iron source) for enhanced Cr(VI) removal. Under optimized conditions (pyrolysis temperature: 800 °C, CS:CROS mass ratio = 1:1), SC@BC demonstrated a maximum Cr(VI) adsorption capacity of 161.13 mg/g. Kinetic analysis revealed that the adsorption process followed a pseudo‐first‐order model, governed by synergistic mechanisms of external diffusion and surface reactions. The removal mechanism involved electrostatic attraction, hydrogen bond, surface complexation, redox reactions, and precipitation, where Fe(II) acted as an electron donor to reduce Cr(VI) to less toxic Cr(III). Subsequent co‐precipitation of Cr(III) with Fe(III) enhanced pollutant immobilization. ICP‐MS analysis confirmed compliance of heavy metal leaching concentrations with GB 13456‐2012 standards, validating environmental safety. This work provides a sustainable “waste‐treats‐waste” strategy for dual‐sludge valorization and high‐efficiency Cr(VI) remediation. Future research should assess SC@BC's scalability for industrial effluents and efficacy in multi‐contaminant systems.

Abstract It has been known that Stress Relaxation Cracking (SRC) in welded joints or cold deformed area is a severe problem for continuous operation in the temperature range between 550 and 750°C in a complex refinery, petrochemical plants etc. In API Technical Report 942-B, SRC susceptibility ranking of heat resistant austenitic stainless steels containing high C content over 0.04% was reported as S31609 < S30409 < S32109 < N08810 < S34709 < N08811. Osuki et al [9] investigated the SRC mechanism with thermodynamic calculations. They studied precipitation hardening by carbide formation at dislocations and softening by Cr depletion through M23C6 precipitation on grain boundaries during stress relaxation at 650 C. Based on this research, S34751 indicated a higher SRC resistance than S34709. In this study, SRC susceptibility of S34752, containing both high Cu and B content was examined because of both the similar alloy design to S34751 and higher creep strength than S34751 and S34709. It was clarified that S34752 indicated higher SRC resistance than S31609, which was reported as having the lowest SRC susceptibility among conventional heat resistant austenitic stainless steels, by the stress relaxation test at 650°C according to ASTM E328.

Experimental investigations were conducted on flexural performance of reinforced concrete (RC) beams with tension sides strengthened with slurry infiltrated fiber concrete (SIFCON) plate. As a result, we reached the following conclusions: (1) Ultimate load of RC beams can be raised nearly twice as large as that of un-strengthened RC beams by this strengthening method. (2) Peeling of SIFCON plate can be prevented up to ultimate load only by adhesive bonding. (3) There is a problem that RC beams strengthened with carbon fiber reinforced plastic plate fail brittlely due to plate-peeling. However, this technique has a possibility of solving the problem.

This study investigates the mineral diversity in placer platinum-group minerals (placer PGM) purportedly collected from the Onnebetsu area in Shibetsu City, Hokkaido. Placer particles consist primarily of native elements and alloys and can be broadly categorized into two groups, iridium-group and palladium-group. The iridium-group placer is predominantly composed of rutheniridosmine, osmium, ruthenium, and iridium, with each occurring as both primary and secondary phases. In contrast, the palladium-group placer consists primarily of isoferroplatinum as the primary phase, accompanied by tulameenite, tetraferroplatinum, and ferronickelplatinum as secondary phases. Notably, the iridium-group placer may also contain PGM typically associated with the palladium-group placer in subordinate amounts. In addition to the primary and secondary phases, other PGM occur as inclusions, within the outermost layers of particles, and in exsolution textures. A total of 41 PGM species were identified in this study, along with six unnamed species. The Onnebetsu area stands out as the region in Japan with the highest diversity of PGM discovered to date. This remarkable variety is largely attributed to the palladium-group placer, which is originated from cumulate rocks formed by partial melting of a mantle.

Metallic titanium ingots can be manufactured via thermal decomposition of titanium sulfides. In our previous study, we thermodynamically and experimentally investigated the phase relationship of titanium oxides and sulfides under carbothermic and hydrogen gas flow atmospheres, that is, non-carbothermic atmospheres. Recently, carbon neutral processes for metallurgical processes that use plant-based biomass, which plays essential roles in environmental protection, have been focused. In this study, the gasification behavior of biomass was investigated by thermal gravimetry-differential thermal analysis, and the deoxidization and sulfurization behaviors that generate titanium sulfides were also experimentally investigated. The gasification behavior differs according to the type of biomass, including the amounts of H2O in the biomass. The reaction temperature for CO2 generation decreased with increasing biomass H2O content. However, the total amounts of generated gas ratios of H2O/CO2 were hardly different, and the partial pressures of oxygen during gasification were also fixed as a function of temperature. The products were analyzed using X-ray diffractometry and identified as titanium disulfide (TiS2), similar to a carbothermic process.