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This study presents an approach to better characterize the P‐wave and S‐wave velocity structure of the seafloor sediment layer using ocean bottom seismometers. The presence of low‐velocity seafloor sediment layers influences the observed seismic record at the seafloor over a broad frequency range, such that detailed knowledge of this sediment structure is essential to predict its effect on teleseismic records. We use the radial component of teleseismic P waves and autocorrelation functions of the radial, vertical, and pressure components of teleseismic P and S waves to obtain sediment layer models using the Markov chain Monte Carlo approach with parallel tempering. Synthetic tests show that the body waves constrain the P‐ and S‐wave impedances and travel times and the P‐ to S‐wave velocity ratio of the sediment layers. The proposed method resolves thin layers at a high resolution, including the uppermost thin (∼50 m to a few hundred meters) low S‐wave velocity layer. Real data applications at sites across the Pacific Ocean that are coincident with previous in situ studies demonstrate the effectiveness of this method in characterizing the seafloor sediment unit. The sediment models characterized by this new approach will allow us to more accurately predict and correct the effects of sediment layers in generating P‐ and S‐wave reverberations. Plain Language Summary: Ocean bottom seismometers are powerful tools for investigating the detailed structure of the oceanic mantle. However, most ocean bottom seismometers are placed above the low‐velocity water‐saturated sediment layer, such that their seismic records are inevitably affected by this seafloor sediment layer. Detailed constraints on the structure of the seafloor sediment layer allow us to accurately predict its effects on the observed seismic records. The seafloor sediment layer may consist of multiple discontinuities and vary regionally. This study proposes a new approach for characterizing the seismic properties of the seafloor sediment layer using teleseismic body waves recorded at ocean bottom seismometers. Synthetic tests show that the method can resolve thin sublayers within the sediment layer, such as a very thin low shear‐wave velocity layer and sharp seismic velocity jumps. Real data applications show that the sediment models obtained using this approach are in good agreement with those obtained from direct measurements and previous body‐wave analyses. Our proposed method will enable more detailed prediction and correction of the influence of the sediment layer on ocean bottom seismometer records, thereby providing more accurate constraints on deeper Earth structures. Key Points: The seismic properties of the seafloor sediment layer are characterized using ocean bottom seismometer teleseismic body‐wave recordsThe P‐ and S‐wave impedances and travel times and the VP/VS values of each sublayer within the sediment layer are resolvedIn situ seafloor sediment structure constraints will enable accurate correction and prediction of shallow structure effects [ABSTRACT FROM AUTHOR]

This study presents reflectivity images of the northeast (NE) Japan subduction zone continuous across the ocean and land. As nearly half of its forearc region is under the ocean, data from ocean bottom seismometers (OBSs) must be utilized to fully image the region by passive seismic analysis. The use of OBS data has been a challenge due to inherent characters of the ocean bottom observations: high noise level and effects of seafloor sediment. Now, decent imaging is possible in NE Japan overcoming the high level noise due to the accumulated data set of the OBSs. The low‐velocity of seafloor sediment significantly delays and amplifies S waves passing through them, and thus complicates teleseismic waveforms. We identify and correct these effects to produce coherent receiver function images throughout the amphibious subduction zone. Our images provide a potential for discussing new structural features and will help better understanding of the dynamics of the NE Japan subduction zone. Plain Language Summary: In northeast Japan, the Pacific plate is subducting beneath the Japanese arc, and delineating how the actual subduction is taking place at depths has been the target of many seismological studies. This study presents our effort of continuous imaging of subsurface interfaces across the ocean and land employing an amphibious data set. On the land side, there are dense seismic networks that have been used to reveal the seismic interfaces using converted phases of distant earthquakes. On the ocean side, the accumulation of data from temporary ocean bottom seismometers in the last decade and the recently installed ocean bottom cable network has made it possible to use a similar approach as on the land. However, the low‐velocity sediment beneath the seafloor causes systematic slower arrivals and larger amplitudes of the seismic phases of interest that result in highly disturbed images if we analyze them in the same way as the land. Here, we identify and correct the effects of the seafloor sediment to analyze the seismic interfaces across the ocean and land. As a result, we succeed in imaging the interfaces of the subducting oceanic crust throughout the region, as well as previously unidentified features under the ocean that may deserve future investigation. Key Points: The northeast Japan subduction zone is imaged using receiver functions (RFs) of an amphibious data setWe identify significant amplitude and time delay effects on RFs from seafloor sedimentCorrections of the sediment effects significantly improve images across an amphibious region [ABSTRACT FROM AUTHOR]

The versatile design of stimuli‐responsive microparticles embedding valuable biomolecules has great potential in a variety of engineering fields, such as sensors, actuators, drug delivery, and catalysis. Here, results are reported on thermoresponsive core–gap–shell (TCGS) microcapsules made of poly(N‐isopropylacrylamide) (PNIPAm), which encapsulate hydrophilic payloads in a simple and stable manner. These are realized by a one‐step microfluidic approach using the phase separation of a supersaturated aqueous solution of NIPAm. Various designs of the microcapsules are achieved by individual control of the swelling or by incorporating pH‐responsive comonomers of the inner core and outer shell. The gap, i.e., the space between the inner core and outer shell, can be loaded with cargo‐like nanoparticles. The outer shell can serve as a stimuli‐responsive gateway for the transport of smaller molecules from the external solution. It is shown that the TCGS microcapsules are suitable as temperature controllable glucose sensors and hold promise in the design of controllable enzymatic reactions. The proposed platform provides an avenue for developing a new‐generation of microparticles for diverse and efficient engineering applications. [ABSTRACT FROM AUTHOR]

The programmed movements of responsive functional hydrogels have received much attention because of their abundant functions and wide range of engineering applications. In this study, an innovative stomata-inspired membrane (SIM) is fabricated by using a temperature-responsive hydrogel through a simple, cost-effective, and high-throughput patterned photopolymerization. Polymerization-induced diffusion on the macroscale surface results in formation of a double-parted polymer membrane with fine pores after single illumination. After heating the SIM, the less deformable thick frame supports the whole structure and the highly deformable thin base regulates pore shape. Among various SIM types, the slit pores of monocot SIM, which are lined up in parallel, exhibit the largest radius deformation. The morphological configuration of the SIM can be easily controlled by changing the photomask for a given application. As the developed SIM features the sensing-to-activation functions of stimuli-responsive hydrogels and can be easily fabricated, this membrane can be potentially used for numerous practical applications, such as filter membranes with adjustable pores, membrane-based sensors, membrane-based actuators, and multifunctional membranes. [ABSTRACT FROM AUTHOR]

Polypyrrole (PPy) is a promising conductive polymer (CP) with electrical versatility, easy synthesis and functionalization, stability, and biocompatibility. Diverse architectures have been adopted to improve PPy performance, but the direct and precise patterning of various architectures remains challenging. Here, the unique formation of a PPy membrane on the air/water interface of a droplet solution containing ammonium persulfate and phytic acid is investigated. When a PPy thin film forms on the air/water interface, the top of the droplet rapidly flattens. The formation procedure and final structure of the PPy thin film are visualized and quantitatively investigated. Unlike the typical globular structure of PPy, the self‐assembled PPy film surface fabricated in this study is very organized and regularly shaped. This well‐ordered membrane may have a very high buckling strength greater than the surface tension of the solution. The proposed precise fabrication method is simple and inexpensive for fabricating patterned functional membranes. These results provide new insight into the fabrication of CP and their applications in various practical electromaterial engineering fields. The unique formation of polypyrrole (PPy) thin film on the air/water interface of a droplet solution containing ammonium persulfate and phytic acid is investigated. The self‐assembled PPy film surface is very organized and regularly shaped. Considering that the precise patterning of various architectures hinders the design of conductive polymers, the proposed method is inexpensive and simple for fabricating patterned functional membranes. [ABSTRACT FROM AUTHOR]

Front Cover: The unique formation of a poly(pyrrole) (PPy) membrane, on the air/water interface of a droplet solution containing ammonium persulfate and phytic acid, is investigated in article number 1800707 by Sang Joon Lee and co‐workers. As polymerization occurs at the air/water interface, a blue‐black PPy clearly forms, and the top of the droplet becomes rapidly flattened. The surface of the fabricated PPy thin film has a well‐organized structure of a pretzel shape. [ABSTRACT FROM AUTHOR]