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Abstract Excitons are fundamental quasiparticles that are ubiquitous in photoexcited semiconductors and insulators. Despite causing a sharp and strong photoabsorption near the interband absorption edge, charge-neutral excitons do not yield photocurrent in conventional photovoltaic processes unless dissociated into free charge carriers. Here, we experimentally demonstrate that excitons can directly contribute to photocurrent generation through a nonlinear light−matter interaction in a noncentrosymmetric semiconductor CuI. Epitaxial thin films of CuI exhibit a substantial enhancement of photocurrent at exciton resonance energies even below the bandgap. From the light polarization dependence, this photocurrent is identified to be shift current, a nonlinear photocurrent driven by the change in the geometric Berry phase of electron wave functions upon the optical transition. The shift current at the exciton resonance is much larger than that induced above the band gap by free electron−hole excitation, and their signs are opposite. First-principles calculations elucidate that the sign and magnitude of the exciton shift current are strongly dependent on the strain in the thin film. The present study reveals the crucial role of excitons in enhancing the shift current magnitude and its strain sensitivity, and will open an unprecedented route for efficient manipulation of nonlinear optical effects.

Abstract Imaging antiferromagnetic 180° domains with actively controlled visibility is vital for both fundamental science and sophisticated applications. While optical second-harmonic generation (SHG) is a well-known technique for distinguishing such domains in non-centrosymmetric antiferromagnets, a general material-based strategy to control domain contrast remains elusive. Using van der Waals antiferromagnet MnPS3 as a proof of concept, we demonstrate the tuning of nonreciprocity-induced domain contrast in SHG through applying an in-plane electric field that transforms the magnetic point group to its unitary subgroup. The interference among intrinsic electric-dipole, magnetic-dipole, and field-induced electric-dipole transitions, each carrying distinct characters under space-inversion ( $${{\mathcal{P}}}$$ P ) and time-reversal ( $${{\mathcal{T}}}$$ T ) operations, enables large tuning of domain contrast and nonreciprocity in a broad spectral range. This strategy, generically applicable to systems characterized by $${{\mathcal{P}}}{{\mathcal{T}}}$$ P T -symmetric magnetic groups with a polar unitary subgroup, offers a path to fast electrical modulation of nonlinear nonreciprocal photonic behaviors using antiferromagnets.

Abstract A naive celestial dictionary causes massless two-point functions to take the delta-function forms in the celestial conformal field theory (CCFT). We rectify the dictionary, involving the shadow transformation so that the two-point functions follow the standard power-law. In this new definition, we can smoothly take the massless limit of the massive dictionary. We also compute a three-point function using the new dictionary and discuss the OPE in CCFT.

Abstract Recent advancements on electrohydrodynamic (EHD) soft pumps demonstrate their applicability to various fluid-driven systems such as soft robots, wearable devices, and stretchable electronics. In particular, fiber type EHD pumps reported more recently is a promising pumping element thanks to their versatile fibrous structure. Yet existing EHD fiber pumps are less stretchable and require sophisticated, complex fabrication equipment, implying opportunity for technology advancement. This paper presents a simplified method to create highly stretchable multifunctional fiber EHD pumps. The method employs highly compliant silicone elastomers for the fiber structure that is formed by simple dipping fabrication process. The fabricated pumps (length of 100 mm, inner diameter 4 mm, and mass 5.3 g) exhibit a high stretchability (up to 40% strain) and flow rate and pressure of 167.4 ± 7.6 mL/min (31.6 mL/min/g) and 4.1 ± 0.6 kPa (0.8 kPa/g), respectively. These performances are comparable or even higher than those of previously reported EHD pumps including fiber types. The output performance of the fabricated pumps remain constant for repeated strain cycles (0–25%, up to 2000 cycles) and bending angle up to 180° (corresponding to curvature of 0–30/m). Moreover, the pumps demonstrate unprecedented functionality as a sensor to distinguish the type of fluid inside the tube and to detect strains by reading the capacitance between the electrodes. The characterization result reveals the sensing ability of the pumps as high repeatability up to 30% strain with negligible hysteresis, which is consistent for 5000 cycles.

Abstract The anomalous Hall effect (AHE) that emerges in antiferromagnetic metals shows intriguing physics and offers numerous potential applications. Magnets with a rutile crystal structure have recently received attention as a possible platform for a collinear-antiferromagnetism-induced AHE. RuO2 is a prototypical candidate material, however the AHE is prohibited at zero field by symmetry because of the high-symmetry [001] direction of the Néel vector at the ground state. Here, we show AHE at zero field in Cr-doped rutile, Ru0.8Cr0.2O2. The magnetization, transport and density functional theory calculations indicate that appropriate doping of Cr at Ru sites reconstructs the collinear antiferromagnetism in RuO2, resulting in a rotation of the Néel vector from [001] to [110] while maintaining a collinear antiferromagnetic state. The AHE with vanishing net moment in the Ru0.8Cr0.2O2 exhibits an orientation dependence consistent with the [110]-oriented Hall vector. These results demonstrate that material engineering by doping is a useful approach to manipulate AHE in antiferromagnetic metals.

Abstract Chemical reduction in oxides plays a crucial role in engineering the material properties through structural transformation and electron filling. Controlling the reduction at nanoscale forms a promising pathway to harvest functionalities, which however is of great challenge for conventional methods (e.g., thermal treatment and chemical reaction). Here, we demonstrate a convenient pathway to achieve nanoscale chemical reduction for vanadium dioxide through the electron-beam illumination. The electron beam induces both surface oxygen desorption through radiolytic process and positively charged background through secondary electrons, which contribute cooperatively to facilitate the vacancy migration from the surface toward the sample bulk. Consequently, the VO2 transforms into a reduced V2O3 phase, which is associated with a distinct insulator to metal transition at room temperature. Furthermore, this process shows an interesting facet-dependence with the pronounced transformation observed for the c-facet VO2 as compared with the a-facet, which is attributed to the intrinsically different oxygen vacancy formation energy between these facets. Remarkably, we readily achieve a lateral resolution of tens nanometer for the controlled structural transformation with a commercial scanning electron microscope. This work provides a feasible strategy to manipulate the nanoscale chemical reduction in complex oxides for exploiting functionalities.

Exciton-magnon pairwise excitation is promising to realize the direct and efficient photogeneration of magnons, especially in low-dimensional materials with large quasiparticle scattering cross sections. Using resonant second-harmonic generation spectroscopy, we identified exciton-magnon resonance in MnPS_{3} with possible splitting, in line with the exciton-induced modification of the magnon density of states based on our Koster-Slater-type theory. The substantial exciton-magnon interaction, favored by symmetry, sheds light on coherent cross control among charge, spin, and orbital degrees of freedom via quasiparticle correlations. Additionally, a large linear magnetoelectric effect of excitons is observed.

Abstract This paper presents a pump using polyvinyl chloride (PVC) gel. PVC gels are compliant, have a simple structure, and exhibit large deformation at voltages in the range of 100–1000 V, which make them suitable for micropumps. In this study, a PVC gel sheet with a surface pattern that enhances active deformation in the thickness direction was employed for the fabrication of a pump. To this end, the PVC gel sheet was sandwiched between three sets of anode and cathode electrodes, after which voltages were sequentially applied to these electrodes to generate a peristaltic deformation of the gel sheet, thus pushing the liquid and creating a one-directional flow. Various pumps were fabricated using PVC gel sheets with different surface patterns, and the pumps were characterized. The pumps exhibited an outline dimension of 35 mm × 25 mm with a thickness of 4 mm, corresponding to a total volume of 3.5 × 103 mm3. The results revealed that the pump fabricated using a 174-μm-high pyramid-patterned gel sheet generated a flow rate of 224.1 µL/min at an applied voltage of 800 V and a driving frequency of 3 Hz. This observed value is comparable to or better than those of existing pumps based on smart materials.

Este trabalho teve por objetivo investigar o efeito do uso de indutores de brotação na quebra da dormência nas cultivares Hosui, Kosui e Suisei.

Electrohydrodynamic (EHD) pumps are a promising driving source for various fluid-driven systems owing to features such as simple structure and silent operation. The performance of EHD pumps depends on the properties of the working fluid, such as conductivity, viscosity, and permittivity. This implies that the tuning of these parameters in a working fluid can enhance the EHD performance. This study reports a method to modify the properties of a liquid for EHD pumps by mixing an additive. Specifically, dibutyl adipate (DBA) and polyvinyl chloride (PVC) are employed as the working fluid and the additive, respectively. The results show that when the concentration of PVC is 0.2%, the flow rate and pressure at applied voltage of 8 kV take highest value of 7.85 μL/s and 1.63 kPa, respectively. These values correspond to an improvement of 109% and 40% for the flow rate and pressure, respectively, compared to the pure DBA (PVC 0%). When the voltage is 10 kV, the flow rate of 10.95 μL/s and the pressure of 2.07 kPa are observed for DBA with PVC concentration of 0.2%. These values are more than five times higher than those observed for FC40 at the same voltage (2.02 μL/s and 0.32 kPa). The results also suggest that optimal conductivity and viscosity values exist for maximizing the EHD performance of a liquid. This demonstrates the validity of the proposed method for realizing high-performance EHD pumps by using additives in the working fluid.

Abstract Background Several microorganisms inhabit the mammalian gastrointestinal tract and are associated with the pathogenesis of various diseases, including cancer. Recent studies have indicated that several probiotics produce antitumor molecules and inhibit host tumor progression. We demonstrated that heptelidic acid (HA), a sesquiterpene lactone derived from the probiotic Aspergillus oryzae, exerts antitumor effects against pancreatic cancer in vitro and in vivo. In this study, the antitumor effects of HA against extraintestinal melanoma were assessed in vitro and in vivo. Results Sulforhodamine B (SRB) assay revealed that the growth of B16F10 cells was significantly inhibited by HA in a concentration-dependent manner. The enzymatic activity of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) decreased in proportion with the growth inhibition effect of HA. Moreover, oral HA administration significantly suppressed the growth of transplanted B16F10 tumors without any significant changes in biochemical test values. Moreover, GAPDH activity in the transplanted tumor tissues in the HA group significantly decreased compared with that in the PBS group. Conclusion This study suggests that orally administered HA was absorbed in the gastrointestinal tract, reached the cancer cells transplanted in the skin, and inhibited GAPDH activity, thereby inhibiting the growth of extraintestinal melanoma cells. Thus, this study proposes a novel system for extraintestinal tumor regulation via gut bacteria-derived bioactive mediators.

Abstract Insects have acquired various types of wings over their course of evolution and have become the most successful terrestrial animals. Consequently, the essence of their excellent environmental adaptability and locomotive ability should be clarified; a simple and versatile method to artificially reproduce the complex structure and various functions of these innumerable types of wings is necessary. This study presents a simple integral forming method for an insect-wing-type composite structure by 3D printing wing frames directly onto thin films. The artificial venation generation algorithm based on the centroidal Voronoi diagram, which can be observed in the wings of dragonflies, was used to design the complex mechanical properties of artificial wings. Furthermore, we implemented two representative functions found in actual insect wings: folding and coupling. The proposed crease pattern design software developed based on a beetle hindwing enables the 3D printing of foldable wings of any shape. In coupling-type wings, the forewing and hindwing are connected to form a single large wing during flight; these wings can be stored compactly by disconnecting and stacking them like cicada wings.

It is difficult to find magnetoelectric low-dimensional structures partly due to the lack of experimental techniques locally probing their physical nature. Here, the authors observe multiferroic ribbon-like domains in a non-multiferroic environment in MnWO4 by optical second harmonic generation.

Abstract Intake of probiotics or fermented food produced by some probiotic bacteria is believed to exert anti-tumor functions in various cancers, including pancreatic cancer, because several studies have demonstrated the anti-tumor effects of probiotic bacteria in vitro and in vivo in animal carcinogenesis models. However, the mechanisms underlying the anticancer effects of probiotics on pancreatic cancer have not been clarified. In this study, we assessed the anti-tumor effects of probiotic bacteria against pancreatic cancer cells. Among the known probiotic bacteria, Aspergillus oryzae exhibited a strong pancreatic tumor suppression effect. The culture supernatant of A. oryzae was separated by HPLC. Heptelidic acid was identified as an anti-tumor molecule derived from A. oryzae by LC–MS and NMR analysis. The anti-tumor effect of heptelidic acid was exhibited in vitro and in vivo in a xenograft model of pancreatic cancer cells. The anti-tumor effect of heptelidic acid was exerted by the p38 MAPK signaling pathway. Heptelidic acid traverses the intestinal mucosa and exerts anti-tumor effects on pancreatic cancer cells. This is a novel anti-tumor mechanism induced by beneficial bacteria against pancreatic cancer in which bacterial molecules pass through the intestinal tract, reach the extra-intestinal organs, and then induce apoptosis via an inducible signaling pathway.

Electrical manipulation of magnetization in devices made of topological materials may be an essential route towards future spintronics technology. Here, Mogi et al. show efficient current-induced switching of surface ferromagnetism in hetero-bilayers of topological insulator (Bi1-xSbx)2Te3 and ferromagnetic insulator Cr2Ge2Te6.

Distress image retrieval for infrastructure maintenance via self-trained deep metric learning using experts’ knowledge is proposed in this paper. Since engineers take multiple images of a single distress part for inspection of road structures, it is necessary to construct a similar distress image retrieval method considering the input of multiple images to support determination of the level of deterioration. Thus, the construction of an image retrieval method while selecting an effective input from multiple images is described in this paper. The proposed method performs deep metric learning by using a small number of effective images labeled by experts’ knowledge with information about their effectiveness and a large number of unlabeled images via a self-training approach. Specifically, an end-to-end learning approach that performs retraining of the model by assigning pseudo-labels to these unlabeled images according to the output confidence of the model is achieved. Thus, the proposed method can select an effective image from multiple images that are input at the retrieval as a query image. This is the main contribution of this paper. As a result, the proposed method realizes highly accurate retrieval of similar distress images considering the actual situation of inspection in which multiple images of a distress part are input.

This study presents a method for distress image classification in road infrastructures introducing self-supervised learning. Self-supervised learning is an unsupervised learning method that does not require class labels. This learning method can reduce annotation efforts and allow the application of machine learning to a large number of unlabeled images. We propose a novel distress image classification method using contrastive learning, which is a type of self-supervised learning. Contrastive learning provides image domain-specific representation, constraining such that similar images are embedded nearby in the latent space. We augment the single input distress image into multiple images by image transformations and construct the latent space, in which the augmented images are embedded close to each other. This provides a domain-specific representation of the damage in road infrastructure using a large number of unlabeled distress images. Finally, the representation obtained by contrastive learning is used to improve the distress image classification performance. The obtained contrastive learning model parameters are used for the distress image classification model. We realize the successful distress image representation by utilizing unlabeled distress images, which have been difficult to use in the past. In the experiments, we use the distress images obtained from the real world to verify the effectiveness of the proposed method for various distress types and confirm the performance improvement.

The Japan Electric Association code, JEAC 4206-2016 specifies a procedure for assessment of a reactor pressure vessel integrity against pressurized thermal shock (PTS) events which postulates a semi-elliptical flaw (10 mm in depth x 60 mm in length) beneath the cladding. JEAC 4206-2016 prescribes a simple method for calculating stress intensity factor of the flaw, taking into account the effect of yielding of cladding which has been originally developed in France. However, since this method is a rather conservative in comparison with that obtained by elastic-plastic finite element analysis, JEAC 4206-2016 also allows to calculate the stress intensity factor by converting the J-integral obtained from elastic-plastic finite element analysis. Since the J-integral is only defined for a linear or nonlinear elastic behavior material, the J-integral cannot be determined for an elastic-plastic behavior material during the unloading phase of PTS events. In addition, the residual stress and plastic strain induced by clad welding and joint welding needs to be considered in calculating the stress intensity factor. In this paper, the calculation procedure for a stress intensity factor of a fully circumferential flaw beneath the cladding during PTS events using finite element analysis is investigated.

This paper presents deterioration level estimation based on convolutional neural networks using a confidence-aware attention mechanism for infrastructure inspection. Spatial attention mechanisms try to highlight the important regions in feature maps for estimation by using an attention map. The attention mechanism using an effective attention map can improve feature maps. However, the conventional attention mechanisms have a problem as they fail to highlight important regions for estimation when an ineffective attention map is mistakenly used. To solve the above problem, this paper introduces the confidence-aware attention mechanism that reduces the effect of ineffective attention maps by considering the confidence corresponding to the attention map. The confidence is calculated from the entropy of the estimated class probabilities when generating the attention map. Because the proposed method can effectively utilize the attention map by considering the confidence, it can focus more on the important regions in the final estimation. This is the most significant contribution of this paper. The experimental results using images from actual infrastructure inspections confirm the performance improvement of the proposed method in estimating the deterioration level.

Spintronic devices are typically controlled with magnetic fields or current injection but incorporating these mechanisms into high-density devices is difficult. Here the authors present an oxide device where the topological and anomalous Hall effects can instead be modulated using an electric field.

This paper presents reliable estimation of deterioration levels via late fusion using multi-view distress images for practical inspection. The proposed method simultaneously solves the following two problems that are necessary to support the practical inspection. Since maintenance of infrastructures requires a high level of safety and reliability, this paper proposes a neural network that can generate an attention map from distress images and text data acquired during the inspection. Thus, deterioration level estimation with high interpretability can be realized. In addition, since multi-view distress images are taken for single distress during the actual inspection, it is necessary to estimate the final result from these images. Therefore, the proposed method integrates estimation results obtained from the multi-view images via the late fusion and can derive an appropriate result considering all the images. To the best of our knowledge, no method has been proposed to solve these problems simultaneously, and this achievement is the biggest contribution of this paper. In this paper, we confirm the effectiveness of the proposed method by conducting experiments using data acquired during the actual inspection.

A single-walled carbon nanotube (SWCNT)-silica composite thin film on a quartz glass was formed by ultraviolet irradiation (20–40 °C) onto a spin-coated precursor film. With 7.4 mass% SWCNTs, the electrical resistivity reached 7.7 × 10−3 Ω·cm after UV-irradiation. The transmittance was >80% at 178–2600 nm, and 79%–73% at 220–352 nm. Heat treatment increased the transparency and pencil hardness, without affecting the low electrical resistivity. Raman spectroscopy and microscopic analyses revealed the excellent film morphology with good SWCNT dispersal. The low refractive index (1.49) and haze value (

Deep-ultraviolet (DUV) light-transparent conductive composite thin films, consisting of dispersed multiwalled carbon nanotubes (MWCNTs) and SiO2 matrix composites, were fabricated on a quartz glass substrate. Transparent and well-adhered amorphous thin films, with a thickness of 220 nm, were obtained by weak ultraviolet (UV) irradiation (4 mW cm−2 at 254 nm) for more than 6 h at 20−40 °C onto the precursor films, which were obtained by spin coating with a mixed solution of MWCNT in water and Si(IV) complex in ethanol. The electrical resistivity of MWCNT/SiO2 composite thin film is 0.7 Ω·cm, and transmittance in the wavelength region from DUV to visible light is higher than 80%. The MWCNT/SiO2 composite thin film showed scratch resistance at pencil hardness of 8H. Importantly, the resistivity of the MWCNT/SiO2 composite thin film was maintained at the original level even after heat treatment at 500 °C for 1 h. It was observed that the heat treatment of the composite thin film improved durability against both aqueous solutions involving a strong acid (HCl) and a strong base (NaOH).

Quantized magnetoelectric coupling, which induces exotic magneto-optical phenomena, awaits to be evidenced in topological insulators. Here, Okada et al. demonstrate Faraday and Kerr rotations of magnetic topological insulator surfaces in quantum anomalous Hall states by terahertz magneto-optics, indicating topological magnetoelectric effect.

The current JSME rules on Fitness-for-Service only applies the Elastic Plastic Fracture Mechanics (EPFM) method, including the two-parameters method for flaw evaluation of cast stainless steel (CASS) pipes, while plastic collapse is expected to occur in the case of low ferrite content or low thermal aging condition. The EPFM method of the JSME rules introduces Z-factor for simplification similar to ASME Sec. XI. The Z-factor equation for CASS pipe was derived with the assumption of a penetrated circumferential flaw, 20% ferrite content, J-R curve of fully aged material, and stress-strain (S-S) curve of unaged material, which are very conservative conditions. In order to revise the current JSME rules for a more practical and accurate flaw evaluation of CASS pipe, this paper introduced to the rules, a limit load method for low ferrite content or low thermal aging condition, and prediction models of S-S and J-R curves for thermal aging. These were verified by fracture tests using flat plate specimens with a surface flaw and detailed FE analyses. Also applicability of a Z-factor equation for an axial flaw was proposed by other authors. This paper is a technical basis for the code revision of the JSME rules.

Mandibular movement is performed by many masticatory muscles. It is important to estimate muscular activities in mastication for examining mechanical function of the movement. However, the estimation method has not yet been established. This study proposes a new method to clarify the cooperative change of muscular lengths using our patient-specific 3-D mandibular motion display system. The method reproduces a mandibular movement from several basic motion modes. The motion modes are expressed by periodic functions with different peak times. The proposed method provides comprehensible information even in a complex mandibular movement. Time series of the muscular lengths are also obtained from the 3-D motion display system. This study discusses a relationship between incisor trajectories and muscular lengths in mandibular movements. We succeeded in reproduction of chewing movements by synthesizing the basic motion modes. With the proposed method, dynamic profiles of masticatory movement show a clear relation to characteristics of the incisor trajectories. We also found all masticatory muscles are cooperatively controlled during mandibular movement. Bilateral difference of contractile muscular lengths and the timings obviously affect the trajectory pattern.

It was investigated whether the C3a-receptor antagonist (C3aRA) SB 290157 was involved in the suppression of anti-OVA pAb–induced arthritis because it is well known that anaphylatoxin C3a plays a crucial role in the development of an effective inflammatory response during complement activation. Anti-OVA pAb–induced arthritis was induced in DBA/1J mice by administration of anti-OVA pAb 0.5 h prior to intra-articular (i.a.) injection of OVA (0 h). Two peaks of joint swelling were observed at 0.5 and 3 h. The role of C3aRA in arthritis was investigated by injection of SB 290157 at concentrations of 10 and 30 mg/kg at 0 and 2 h. The antagonist was able to reduce joint swelling only at 3 h, and about 50% inhibition of joint swelling was observed with the concentration of 30 mg/kg. The C3 level was significantly decreased at 3 h compared with naïve mice showing complement consumption. Furthermore, the C3 activation was observed and increased corresponding to the graded concentration of anti-OVA pAb. The results also revealed that the C3aRA was able to reduce the expression of IL-1β in synovial tissue. Taken together, the results suggested that C3aRA may be effective in the inhibition of arthritis. Keywords:: rheumatoid arthritis, OVA, anti-OVA antibody–induced arthritis, C3a-receptor antagonist, inflammation