A multilayer Mg-Al-Zn/Mg-Zn-Y composite material was fabricated for the first time via a vacuum gravity casting process combined with subsequent hot extrusion. Comprehensive microstructural characterization was conducted to systematically elucidate the microstructure evolution, texture transition, dynamic recrystallization (DRX) behavior, and deformation mechanisms of the composite. The results show that this processing strategy forms an interface with good metallurgical bonding and serrated mechanical interlocking characteristics, ensuring structural integrity and effective load transfer. Interrupted extrusion experiments revealed significant layer-dependent DRX. The premature deformation and DRX of the softer Mg-Al-Zn layer led to the formation of coarse DRXed grains in the extruded Mg-Al-Zn layer, while the harder Mg-Zn-Y layer exhibited delayed and restricted DRX due to rare earth element addition, forming a bimodal grain microstructure. The temporal and spatial asymmetry in DRX kinetics resulted in a multimodal laminated microstructure. During room-temperature tensile deformation, significant strain partitioning occurred between the soft and hard layers. Plastic strain was initially accommodated by the Mg-Al-Zn layer and gradually transferred to the Mg-Zn-Y layer, thus enabling coordinated deformation at higher strain levels. Simultaneously, the continuous accumulation of dislocations near the heterogeneous interface activates heterogeneous deformation-induced (HDI) strengthening. The interlayer strain partitioning and dislocation accumulation at the heterointerface cause the composite material's work hardening capacity to exceed the predictions of the rule of mixtures.
We investigate the microscopic origin of size-dependent magnetization suppression in Ni nanocrystals using photoemission measurements with variable probing depth. While the interior retains bulklike electronic states, the near-surface region exhibits enhanced electronic correlation, leading to conduction-electron localization and the emergence of a magnetic dead layer. This intrinsic modification proves the validity of the dead-layer model quantitatively describing the size dependence of the saturation magnetization. These findings establish a direct link between surface electronic correlation and magnetism at reduced dimensions.
Noctiluca scintillans is a globally distributed harmful algal bloom (HAB) species known for potentially causing fish mortality and economic losses to fisheries. N. scintillans tends to accumulate near the sea surface, making it particularly susceptible to transport by ocean currents, however, direct evidence of long-distance dispersal has remained limited. Year-round monitoring in Kumamoto revealed that the Indonesian (Jakarta-type, K2) genotype occurs predominantly during the autumn high-abundance period, coinciding with smaller cell sizes that match Jakarta population. To evaluate the plausibility of long-distance transport, we conducted Lagrangian particle-tracking simulation using OSCAR surface currents. The results showed a plausible physical ocean connectivity between Indonesia and Japan within 600 days, with consistent patterns across different particle-release numbers indicating that arrival probabilities remained low but spatially robust. Recognizing that OSCAR provides a 0.25° satellite-derived representation of basin-scale surface circulation that does not explicitly resolve mesoscale eddies, we interpret these trajectories as possible connectivity pathways rather than literal particle tracks. Together, our genetic, morphological, and particle-tracking simulation results indicate that N. scintillans populations in Yatsushiro Bay likely consist of both regional and foreign genetic contributors, highlighting the potential for long-range connectivity under contemporary circulation patterns.
Polycrystalline diamond (PCD) tools have gained attention for machining nonferrous metals, nonmetals, and composite materials. However, chipping at the cutting edge and unevenness on the flank face introduced during manufacturing result in reduced surface accuracy and shortened tool life. To address these issues, this study proposes a novel tribochemical polishing technique for the flank face of PCD tools that involves heating the polishing disk. This technique effectively reduces chipping and cracking at the cutting edge, which are difficult to prevent using conventional methods, and enables sharpening of the cutting edge and precise adjustment of its shape. Furthermore, the cutting performance of tribochemically polished PCD tools was evaluated by machining a titanium alloy (Ti-6Al-4 V). The results demonstrated improved surface accuracy, reduced adhesion, and extended tool life compared to commercial tools. This study is expected to contribute to the development of high-precision and stable machining of difficult-to-cut titanium alloys through advancements in PCD tool technology.
A group of temperate grassland plant species, referred to as the 'Mansen elements,' is found in Japan and extensively distributed in the grasslands of continental East Asia. It has been considered that these species are remnants of once-expanded grasslands in Japan during a colder geological era. However, the detailed phylogeographic history, including migration age and distributional changes within Japan for these species, remains unresolved. To elucidate the phylogeographic history of the Mansen elements, we investigated the genetic structure and phylogeny of the populations ofPulsatilla cernua, one of the Mansen elements, using single-nucleotide polymorphisms (SNPs) obtained from multiplexed inter-simple sequence repeat genotyping by sequencing (MIG-seq). The phylogenetic analysis indicates a continental origin and migration route via the Korean Peninsula for P. cernua. The DIYABC and the genetic structure analyses suggest that the divergence between the continental and Japanese populations occurred the late stage of the Last Glacial Period (LGP). Although the estimated divergence time is not fully constrained, it is suggested that an initial expansion in Japan occurred before the Last Glacial Maximum (LGM). This once-expanded distribution area was subsequently fragmented during the coldest climate, followed by a secondary expansion after the LGP. This represents the first documented instance among the Mansen element species in which secondary range expansion brought fragmented populations into secondary contact.
