Showing papers by "National Institute of Advanced Industrial Science and Technology published in 2022"

BCFT and Islands in two dimensions

Abstract: A bstract By combining the AdS/BCFT correspondence and the brane world holography, we expect an equivalence relation between a boundary conformal field theory (BCFT) and a gravitational system coupled to a CFT. However, it still remains unclear how the boundary condition of the BCFT is translated in the gravitational system. We examine this duality relation in a two-dimensional setup by looking at the computation of entanglement entropy and energy flux conservation. We also identify the two-dimensional gravity which is dual to the boundary dynamics of a BCFT. Moreover, we show that by considering a gravity solution with scalar fields turned on, we can reproduce one point functions correctly in the AdS/BCFT.

Physical and chemical aspects at the interface and in the bulk of CuInSe₂-based thin-film photovoltaics

Abstract: Chalcopyrite CuInSe2 (CISe)-based thin-film photovoltaic solar cells have been attracting attention since the 1970s. The technologies of CISe-based thin-film growth and device fabrication processes have already been put into practical applications and today commercial products are available. Nevertheless, there are numerous poorly understood areas in the physical and chemical aspects of the underlying materials science and interfacial and bulk defect physics in CISe-based thin-films and devices for further developments. In this paper, current issues in physical and chemical studies of CISe-based materials and devices are reviewed. Correlations between Cu-deficient phases and the effects of alkali-metals, applications to lightweight and flexible solar minimodules, single-crystalline epitaxial Cu(In,Ga)Se2 films and devices, differences between Cu(In,Ga)Se2 and Ag(In,Ga)Se2 materials, wide-gap CuGaSe2 films and devices, all-dry processed CISe-based solar cells with high photovoltaic efficiencies, and also fundamental studies on open circuit voltage loss analysis and the energy band structure at the interface are among the main areas of discussion in this review.

Interstellar gas heating by primordial black holes

Abstract: Interstellar gas heating is a powerful cosmology-independent observable for exploring the parameter space of primordial black holes (PBHs) formed in the early Universe that could constitute part of the dark matter (DM). We provide a detailed analysis of the various aspects for this observable, such as PBH emission mechanisms. Using observational data from the Leo T dwarf galaxy, we constrain the PBH abundance over a broad mass-range, $M_{\rm PBH} \sim \mathcal{O}(1) M_{\odot}-10^7 M_{\odot}$, relevant for the recently detected gravitational wave signals from intermediate-mass BHs. We also consider PBH gas heating of systems with bulk relative velocity with respect to the DM, such as Galactic clouds.

Deserpentinization and high-pressure (eclogite-facies) metamorphic features in the Eoarchean ultramafic body from Isua, Greenland

Abstract: Discontinuous chains of ultramafic rock bodies form part of the 3800–3700 Ma Isua Supracrustal Belt (ISB), hosted in the Itsaq Gneiss Complex of southwestern Greenland. These bodies are among the world’s oldest outcrops of ultramafic rocks and hence an invaluable geologic record. Ultramafic rocks from Lens B in the northwestern limb of ISB show characteristics of several stages of serpentinization and deserpentinization forming prograde and retrograde mineral assemblages. Ti-rich humite-group minerals such as titanian chondrodite (Ti-Chn) and titanian clinohumite (Ti-Chu) often occur as accessory phases in the metamorphosed ultramafic rocks. The Ti-rich humite minerals are associated with metamorphic olivine. The host olivine is highly forsteritic (Fo96-98) with variable MnO and NiO contents. The concentrations of the rare-earth elements (REE) and high-field strength elements (HFSE) of the metamorphic olivine are higher than typical mantle olivine. The textural and chemical characteristics of the olivine indicate metamorphic origin as a result of deserpentinization of a serpentinized ultramafic protolith rather than primary assemblage reflecting mantle residues from high-degrees of partial melting. The close association of olivine, antigorite and intergrown Ti-Chn and Ti-Chu suggests pressure condition between ∼1.3–2.6 GPa within the antigorite stability field (

Achieving high strength and toughness by engineering 3D artificial nacre-like structures inTi6Al4V-Ti metallic composite

Abstract: Bio-inspired mimicking natural structures generally duplicate the three dimensional “hard brick-and-soft mortar” structure that may overcome the intrinsic brittleness of the brick, resulting in an improved mechanical performance. Here for the first time, we proposed an anti-bioinspired strategy of designing metallic composite with soft bricks (pure Ti) confined by hard mortars (Ti6Al4V alloy). The three-dimensional minority of hard mortar (with a volume fraction of ∼14%) is fabricated by using selective laser melting (SLM), while the bricks are introduced by filling the pure titanium powders followed by the hot isostatic pressing. The resulting nacre-like structured composite reveals a distinct periodic distribution of “soft-brick” and “hard-mortar” domains by a well-bonded interface with a well-bonded interface between them. This unique composite structure exhibits a combination of high strength and high fracture toughness that both exceed the respective value calculated using the rule of mixtures (ROM). Three dimensional heterogenous plastic deformations between the two domains induce the mechanical incompatibility, which has been confirmed by the presence of higher density of geometrically necessary dislocations (GNDs) in front of the interface. The large amount of GNDs was believed primarily responsible for the extraordinary strengthening and toughening beyond the ROM. This novel strategy of designing artificial three dimensional “soft brick-and-hard mortar” structure could be further applied to other metals and alloys, shedding lights on the development of innovative heterogeneous materials relevant to industry.

Stress Map of Japan: Detailed Nationwide Crustal Stress Field Inferred From Focal Mechanism Solutions of Numerous Microearthquakes

Abstract: Crustal stress is a crucial parameter for understanding tectonics and assessing the occurrence of large earthquakes. Stress at seismogenic depths over a wide area has been inferred from focal mechanism solutions. The existence of focal mechanism solutions determines the area that can be potentially studied. Therefore, we studied the crustal stress orientations in Japan from focal mechanism solutions of small earthquakes. First, we obtained about 220,000 focal mechanisms using the P-wave first-motion polarities picked by a deep learning model. Next, we performed a linearized inversion on the nationwide stress orientation model at a grid of 0.2-degree intervals. The estimation errors reflect the quality and quantity of focal mechanism solutions. Overall, the results indicate that Japanese islands are under an east–west compressional stress, whereas some areas along the Pacific coast of northeast Japan are under east–west extensional stress. A closer look shows the spatial trends of stress orientation may vary near the geological borders, including the Hinagu and Futagawa faults in Kumamoto Prefecture (Kyushu Island) and the Median Tectonic Line in Shikoku Island. Our stress model also revealed the existence of stress anomalies around Cape Shionomisaki in the Kii peninsula. Most of the active faults are at approximately optimal orientation for the derived stress orientation and stress ratio, although uncertainties in the fault geometry, particularly the dip angle, substantially affect this evaluation. The stress map helps understand the overall vision of the crustal stress in Japan and further study the local stress distribution.

CO2 hydrogenation to methanol by organometallic catalysts

Abstract: CO2 conversion is one of the essential technologies for the reduction of CO2 emissions. As methanol is extensively used as a raw material for plastics and fuels, methanol production from CO2 is a promising method to reduce CO2 emissions. However, heterogeneous catalysts for CO2 hydrogenation to methanol suffer from low conversion and selectivity owing to equilibrium limitations at high temperature. In contrast, organometallic catalysts can perform at relatively low temperatures compared with heterogeneous catalysts. Additionally, an appropriate ligand design can improve the activity and selectivity of organometallic catalysts. In CO2 hydrogenation to methanol using organometallic catalysts, although extensive research on indirect synthesis methods has been performed, significant progress has recently been made in direct synthesis. This perspective provides an overview of the current state of indirect and direct methods for methanol production from CO2 via the design of organometallic catalysts and reaction processes.

Brane dynamics of holographic BCFTs

Abstract: A bstract In this paper we study various dynamical aspects of the AdS/BCFT correspondence in higher dimensions. We study properties of holographic stress energy tensor by analyzing the metric perturbation in the gravity dual. We also calculate the stress energy tensor for a locally excited state on a half plane in a free scalar CFT. Both of them satisfy a reflective boundary condition that is expected for any BCFTs. We also study the behavior of the scalar field perturbation in the AdS/BCFT setup and show that they also show complete reflections. Moreover, we find that the entanglement entropy of a BCFT computed from the AdS/BCFT matched with that calculated from the Island formula, which supports the Island/BCFT correspondence in higher dimensions. Finally we show how we can calculate one point functions in a BCFT in our gravity dual.

Extrafollicular PD-1highCXCR5–CD4+ T cells participate in local immunoglobulin production in nasal polyps

Abstract: Local immunoglobulin hyperproduction is observed in nasal polyps (NPs) with and without ectopic lymphoid tissues (eLTs).Our aim was to identify the T-cell subsets involved in local immunoglobulin production independent of eLTs in NPs.The localization, abundance, and phenotype of CD4+ T-cell subsets were studied by immunofluorescence, flow cytometry, and single-cell RNA sequencing. Purified nasal T-cell subsets were cultured with autologous peripheral naive B cells to explore their function. Programmed death ligand 1 and programmed death ligand 2 expression in NPs was investigated by immunofluorescence staining and flow cytometry.Accumulation of PD-1highCXCR5-CD4+ T cells outside lymphoid aggregates was found in NPs. Nasal PD-1highCXCR5-CD4+ T cells were characterized by a unique phenotype that was related to B-cell help and tissue residency and distinct from PD-1-/intCXCR5- and CXCR5+ CD4+ T cells in NPs as well as PD-1highCXCR5highCD4+ follicular helper T cells in tonsils. Compared with the frequencies of PD-1highCXCR5-CD4+ T cells and their IFN-γ+, IL-17A+, and IL-21+ subsets in the control inferior turbinate tissues, the frequencies of these cells and their subsets were increased in both eosinophilic and noneosinophilic NPs, whereas the frequencies of the IL-4+ and IL-4+IL-21+ subsets were increased only in eosinophilic NPs. Nasal PD-1highCXCR5-CD4+ T cells induced immunoglobulin production from B cells in a potency comparable to that induced by tonsillar follicular helper T cells. PD-1highCXCR5-CD4+ T-cell frequencies were correlated with IgE levels in eosinophilic NPs. PD-L1 and PD-L2 suppressed the function of PD-1highCXCR5-CD4+ T cells, and their levels were reduced in NPs. PD-1highCXCR5-CD4+ T-cell abundance was associated with the postsurgical relapse of NPs.PD-1highCXCR5-CD4+ T cells participate in local immunoglobulin production independent of eLTs in NPs.

Curcumin activates Nrf2/ <scp>HO</scp> ‐1 signaling to relieve diabetic cardiomyopathy injury by reducing <scp>ROS</scp> in vitro and in vivo

Abstract: The hallmark feature of Diabetes mellitus (DM) is hyperglycemia which can lead to excess production of reactive oxygen species (ROS) in the myocardium, contributing to diabetic cardiomyopathy (DCM). Nuclear factor erythroid2-related factor2 (Nrf2), a transcriptional activator, enhances its ability to resist oxidative stress by activating multiple downstream anti-oxidants, anti-inflammatory proteins, and detoxifying enzymes. However, the mechanism of Nrf2 signaling in HG-induced DCM is unclear. In this study, we used HG pretreated H9c2 cells as the experimental basis in vitro, and established a high fat-diet, streptozotocin (STZ) induced Type 2 diabetic rat model in vivo. Meanwhile, we used shRNA-Nrf2 and curcumin (CUR) (as an activator) to affect H9c2 cells, to verify the role of the Nrf2 signaling pathway in DCM. The results showed that the excessive production of ROS caused by HG, which could inhibit the activation of Nrf2-related signaling, resulting in a decrease in cell energy metabolism and an increase in cell apoptosis. Surprisingly, we found that the activation of the Nrf2 signaling pathway significantly increased cardiomyocyte viability, reduced ROS formation, increased antioxidant enzyme activity, and inhibited cardiomyocyte apoptosis. In conclusion, these findings conclusively infer that CUR activation of the Nrf2/HO-1 signaling pathway exerts myocardial protection by reducing ROS formation.

Permeability Measurement and Prediction with Nuclear Magnetic Resonance Analysis of Gas Hydrate-Bearing Sediments Recovered from Alaska North Slope 2018 Hydrate-01 Stratigraphic Test Well

Abstract: Permeability of porous media, such as oil and gas reservoirs, is the crucial material parameter for predicting their hydraulic behavior. A nuclear magnetic resonance (NMR) analyzer is widely used as a powerful tool to predict permeability of various media. NMR T2 (transverse or spin–spin) relaxation time distribution, which is related to pore size distribution, gives the information to allow calculation of effective (initial) permeability. In this study, we investigate effective, intrinsic (absolute), and relative water and gas permeabilities of hydrate-bearing pressure core samples. These samples were recovered from the Alaska North Slope 2018 Hydrate-01 Stratigraphic Test Well by sidewall pressure coring and then analyzed in a laboratory using both fluid flow test and NMR analyzer. The peak of the NMR T2 distribution was measured at 10–20 ms using a laboratory NMR analyzer, which compares well with in situ measurements obtained via logging while drilling NMR data for two samples with high gas hydrate saturations (Sh = 76% and 74%). Further, comparison of laboratory NMR T2 distribution after hydrate dissociation revealed that the hydrate existed in large pore spaces. Effective permeabilities predicted by the Timur-Coates (TC) model and the Schlumberger-Doll-Research (SDR) model, with T2 cutoff 33 ms, were about an order of magnitude less than the laboratory measured values. Alternative TC model-based calculations with the T2 cutoff reduced to 10 ms and a newly developed hydraulic radius model better matched the laboratory data. For the analysis of the intrinsic permeabilities, the TC model with a T2 cutoff of 33 ms and SDR model were greater than the laboratory derived values, while the hydraulic radius model more closely matched the laboratory-derived values. In addition, permeability measurements were also made relative to gas and water under constant three-phase flow (water–gas–hydrate) conditions. After hydrate dissociation, a relative permeability curve was developed for each of the analyzed core samples based on the Corey petrophysical model. The results indicate that the gas permeability changed rapidly at high water saturation around 90%. Thus, we infer that the selection of relative reservoir parameters should focus on the higher water saturation conditions.