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Dissimilatory iron reduction (DIR) is suggested to be one of the earliest forms of microbial respiration. It plays an important role in the biogeochemical cycling of iron in modern and ancient sediments. Since microbial iron cycling is typically accompanied by iron isotope fractionation, stable iron isotopes are used as tracer for biological activity. Here we present iron isotope data for dissolved and sequentially extracted sedimentary iron pools from deep and hot subseafloor sediments retrieved in the Nankai Trough off Japan. Dissolved iron (Fe(II)aq) is isotopically light throughout the ferruginous sediment interval but some samples have exceptionally light isotope values. Such light values have never been reported in natural marine environments and cannot be solely attributed to DIR. We show that the light isotope values are best explained by a Rayleigh distillation model where Fe(II)aq is continuously removed from the pore water by adsorption onto iron (oxyhydr)oxide surfaces. While the microbially mediated Fe(II)aq release has ceased due to an increase in temperature beyond the threshold of mesophilic microorganisms, the abiotic adsorptive Fe(II)aq removal continued, leading to uniquely light isotope values. These findings have important implications for the interpretation of dissolved iron isotope data especially in deep subseafloor sediments. [ABSTRACT FROM AUTHOR]

This paper presents a time-varying model-based method for estimating earthquake-induced displacement responses of building structures using limited acceleration data. First, a time-varying model which considers the variability of stiffness by a time-variant story local stiffness reduction factor and the variability of damping by formulating the Rayleigh damping model with a time-variant mass coefficient was developed. Then, a displacement estimation algorithm was derived on the basis of the state space representation of the time-varying model and the unscented Kalman filter. The effectiveness of the proposed method is numerically verified through nonlinear responses of a ten-story building model where the hysteretic restoring force is simulated by the Bouc–Wen model. In addition, numerical results indicated that a few sensors with low noise are more desirable for the measurement strategy. Finally, the applicability to realistic seismic monitoring of buildings was investigated through a 1∶3-scale 18-story steel frame test at the E-Defense shaking table facility, which tested collapse behavior and realistic damage of high-rise steel buildings constructed in the 1990s in Japan. [ABSTRACT FROM AUTHOR]

Airline industry CO 2 emissions have increased rapidly; air transportation released approximately 2.8% of global fuel-combustion-based CO 2 emissions in 2019. Focusing on Japan, this study explored the introduction of new passenger aircraft as a CO 2 -reduction policy. To this end, the lifetime distribution function for passenger aircraft was specified. Lifecycle CO 2 emissions and the associated costs between 1965 and 2019 were then estimated. The results showed that single-aisle aircraft followed a Rayleigh distribution with a mean of 13.42, while twin-aisle aircraft followed a normal distribution with a mean of 19.82. The reduction potential of lifecycle CO 2 emissions is 28.2 Mt. over 55 years by extending the lifetime +11 years of single-aisle aircraft and shortening the lifetime −8 years of twin-aisle aircraft. If the average fuel intensity of aircraft inflow improves steadily, the shortened lifetime and introduction of more fuel-efficient aircraft contribute to a decrease in lifecycle CO 2 emissions. However, the cost associated with the lifecycle CO 2 emission reductions is USD 94.0 billion, and airlines need to pay USD 3.4 thousand to reduce CO 2 emissions by one unit. In sum, the introduction of new aircraft was shown to be cost-ineffective as a CO 2 -reduction policy, and airlines need to switch to less costly alternatives. • This study explored the introduction of new aircraft as a CO 2 -reduction policy. • The lifetime distribution function for passenger aircraft was specified. • The reduction potential of lifecycle CO 2 emissions is 28.2Mt between 1965 and 2019. • The cost associated with the lifecycle CO 2 emission reductions is USD 94.0 billion. • The introduction of new aircraft was not cost-effective as a CO 2 -reduction policy. [ABSTRACT FROM AUTHOR]