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Masushi Kohta,1 Yoshinori Nakamura,2,3 Shunji Yunoki4 1Medical Engineering Laboratory, ALCARE Co., Ltd, Tokyo, Japan; 2Department of Medical Home Healthcare Center, Tenri Hospital Shirakawa Branch, Nara, Japan; 3Pressure Injury Research Center for Home Healthcare, Nara, Japan; 4Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Tokyo, JapanCorrespondence: Masushi KohtaMedical Engineering Laboratory, ALCARE Co., Ltd, 1-21-10 Kyojima, Sumida-ku, Tokyo, 131-0046, JapanTel +81-3-3611-1101Fax +81-3-3613-6894Email mkouta@alcare.co.jpPurpose: This study evaluated the effect of a new secondary dressing used as a topical aid sliding sheet for friction and shear force reduction on the mechanical stresses generated on human skin, including interface friction and internal shear force and pressure, using a polyurethane gel-based skin model. A case study was conducted to propose on how to clinically use the topical aid sliding sheet for pressure injury treatment in a home-care setting.Methods: A polyurethane gel-based skin model mimicking the mechanical properties of human skin was prepared. In parallel measurement of interface friction and internal shear force and pressure was performed using an experimental model consisting of the skin model, primary wound dressing, topical aid sliding sheet, and three-axis tactile sensor. The skin model was covered with the following single or combined dressings: group A, silicone-faced absorbent dressing (control); group B, silicone-faced absorbent dressing plus film dressing; and group C, silicone-faced absorbent dressing plus topical aid sliding sheet. Clinically, a standard primary wound dressing was applied to a female patient (age, 101 years) with pressure injury on the sacral region, and the dressing was overwrapped with the topical aid sliding sheet.Results: The static and dynamic coefficients of friction were significantly lower in group C than in groups A and B (p < 0.05). The detected shear force in the skin model was reduced to approximately 66% and 62% in group C versus groups A and B, respectively (p < 0.05). Clinically, the patient’s ulcer underwent complete epithelialization without wound-related complications.Conclusion: The topical aid sliding sheet significantly reduced interface friction and internal shear forces in the present skin model. The case study’s result showed the topical aid sliding sheet had the potential to use for pressure injury treatment at a home care.Keywords: pressure ulcer, tissue viability, dressing, mechanical force, wound care, shear force, friction

Takefumi Narita,1 Shunji Yunoki,1 Yoshimi Ohyabu,1 Naohisa Yahagi,2 Toshio Uraoka3 1Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, Koto-ku, 2Division of Research and Development for Minimally Invasive Treatment, Cancer Center, Keio University School of Medicine, Shinjuku-ku, 3Department of Gastroenterology, National Hospital Organization Tokyo Medical Center, Meguro-ku, Tokyo, Japan Abstract: We investigated the potential of collagen–genipin sols as biomaterials for treating artificial ulcers following endoscopic submucosal dissection. Collagen sol viscosity increased with condensation, allowing retention on tilted ulcers before gelation and resulting in collagen gel deposition on whole ulcers. The 1.44% collagen sols containing genipin as a crosslinker retained sol fluidity at 23°C for >20 min, facilitating endoscopic use. Collagen sols formed gel depositions on artificial ulcers in response to body temperature, and high temperature responsiveness of gelation because of increased neutral phosphate buffer concentration allowed for thick gel deposition on tilted ulcers. Finally, histological observations showed infiltration of gels into submucosal layers. Taken together, the present data show that genipin-induced crosslinking significantly improves the mechanical properties of collagen gels even at low genipin concentrations of 0.2–1 mM, warranting the use of in situ gelling collagen–genipin sols for endoscopic treatments of gastrointestinal ulcers. Keywords: collagen, genipin, in-situ gel, fibril formation, ulcer dressing

Shunji Yunoki,1 Masushi Kohta,2 Yoshimi Ohyabu,1 Tetsuji Iwasaki2 1Biotechnology Group, Tokyo Metropolitan Industrial Technology Research Institute, 2Medical Engineering Laboratory, ALCARECo., Ltd, Tokyo, Japan Purpose: This study evaluated the in vitro antibacterial activity and cytotoxicity of various commercially available silver-containing dressings (Ag dressing). Methods: Biohesive Ag (hydrocolloid, silver sulfadiazine), Aquacel® Ag (nonwoven fabric, ionic silver [Ag+]), Algisite™ Ag (nonwoven fabric, Ag+), Mepilex® Ag (foam, silver sulfate), and PolyMem® Ag (foam, nanocrystalline silver) were tested for characteristics of Ag+ release, antibacterial activity, and cytotoxicity. The release of Ag+ was investigated in cell culture medium at immersion periods of 6, 24, and 48 hours. The antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa were accessed by a disc diffusion test. The cytotoxicity was evaluated using V79 cells, by an extraction method. Results: The cytotoxicity was not a monotonic function of the antibacterial activity among the Ag dressings and could not be simply explained by Ag+-release properties. Biohesive Ag was regarded as a slow-release Ag dressing, showing the lowest cytotoxicity, while the antibacterial activity was classified as “strong” or “significant” against the two species of bacteria. Aquacel Ag and Algisite Ag showed higher antibacterial activity and cytotoxic effects, which were supported by the higher Ag+ release. Mepilex Ag showed the highest release of Ag+, and the cytotoxicity was the highest among the Ag dressings. However, the antibacterial activity was classified as “significant” or “no activity” for P. aeruginosa and S. aureus, respectively. PolyMem Ag showed the lowest Ag+ release, and the antibacterial activity classified as “significant" or "no activity” for S. aureus and P. aeruginosa, respectively, whereas the cytotoxicity was similar to those of Aquacel Ag and Algisite Ag. Conclusion: The efficacy and adverse effects of the Ag dressings revealed differences that should be considered by clinicians during wound management. Keywords: ionic silver, silver sulfadiazine, nanocrystalline silver, wound management, wound infection, slow release

The optical conductivity (σ1) of SrTiO3 for various vacancies has been systematically studied using a combination of ultraviolet-vacuum ultraviolet reflectivity and spectroscopic ellipsometry. For cation (Ti) vacancies, σ1 shows large spectral weight transfer over a wide range of energy from as high as 35 eV to as low as 0.5 eV and the presence of mid-gap states, suggesting that strong correlations play an important role. Meanwhile, for anion (O) vacancies, σ1 shows changes from 7.4 eV up to 35 eV. [ABSTRACT FROM AUTHOR]

The electronic and adsorption properties of chemically modified square hexagonal boron nitride quantum dots are investigated using density functional theory calculations. The free energy and frequency calculations show that all the boron nitride flakes are stable before/after modification and metal adsorption. Edge modification significantly enhances the stability and interactivity of the flake. For instance, the free energy of binding decreases from −6.5 eV in the hydrogenated flake to −7.1 eV in the pristine one and the dipole moment increases from 4.5 D to 53.7 D, respectively. A wide spectrum of band gaps can also be achieved, where the band gap can be smoothly varied from ∼6 eV in edge fluorinated flakes to 0.2 in sulfurated ones. Six hydrated metals, Cd, Co, Cr, Cu, Fe, and Zn, are considered for adsorption by the flakes. The transition metals are highly selected by the flakes while heavy metals are weakly adsorbed. All hydrated metals are physically adsorbed by the edge and surface of hydrogenated flakes except Cu, which is chemically adsorbed. Chemical groups or elements attached to the flake strongly enhance the adsorption strength; the adsorption energy of hydrated Cr on the surface increases from 0.6 eV to 8.6 eV after attaching two COOH groups to the surface. Hydrogen evolution has also been observed through the adsorption process. The calculated low overpotential for the oxygen evolution reaction (0.52 V) and hydrogen adsorption strength (0.11 eV) for the hydrogen evolution reaction indicate that boron nitride quantum dots are not only potential candidates for the removal of different metals from wastewater but also for efficient water splitting. [ABSTRACT FROM AUTHOR]

Abstract: We theoretically study a spin Hall effect of normal metal in a superconductor/normal metal (SN) junction based on perturbation theory. The skew scattering and side jump contributions are both taken into account to calculate the spin Hall conductivity (SHC) in the normal metal. We fin that both contributions are anomalously enhanced when the voltage (eV) between the superconductor and the normal metal approaches to the superconducting gap (Δ0). We also fin that the SHC at eV =Δ0 increases with decreasing the junction resistance (RT). These results clearly demonstrate that the SHC in SN junctions can be controlled by applying an external dc electric fiel and by varying RT, suggesting that SN junctions have potential applications for spintronic devices with large spin Hall effects. [Copyright &y& Elsevier]

We propose a spin Hall device to induce a large spin Hall effect in a superconductor/normal-metal (SN) junction. The side jump and skew scattering mechanisms are both taken into account to calculate the extrinsic spin Hall conductivity in the normal metal. We find that both contributions are anomalously enhanced when the voltage between the superconductor and the normal metal approaches to the superconducting gap. This enhancement is attributed to the resonant increase of the density of states in the normal metal at the Fermi level. Our results demonstrate a way to control and amplify the spin Hall conductivity by applying an external dc electric field, suggesting that SN junctions have potential applications for spintronic devices with large spin Hall effects. [ABSTRACT FROM AUTHOR]

In this proceeding, recent theoretical investigations by the authors on the multiferroic RMnO3 perovskites are briefly reviewed at first. Using the double-exchange model, the realistic spiral spin order in undoped manganites such as TbMnO3 and DyMnO3 is well reproduced by incorporating a weak next-nearest neighbor superexchange (~10% of nearest neighbor superexchange) and moderate Jahn-Teller distortion. The phase transitions from the A-type antiferromagnet (as in LaMnO3), to the spiral phase (as in TbMnO3), and finally to the E-type antiferromagnet (as in HoMnO3), with decreasing size of the R ions, were also explained. Moreover, new results of phase diagram of the three-dimensional lattice are also included. The ferromagnetic tendency recently discovered in the LaMnO3 and TbMnO3 thin films is explained by considering the substrate stress. Finally, the relationship between our double-exchange model and a previously used J1-J2-J3 model is further discussed from the perspective of spin wave excitations. [ABSTRACT FROM AUTHOR]

By combining the tetrahedron method with the cluster perturbation theory (CPT), we present an accurate method to numerically calculate the density of states of interacting fermions without introducing the Lorentzian broadening parameter η or the numerical extrapolation of η→0. The method is conceptually based on the notion of the effective single-particle Hamiltonian which can be subtracted in the Lehmann representation of the single-particle Green's function within the CPT. Indeed, we show the general correspondence between the self-energy and the effective single-particle Hamiltonian which describes exactly the single-particle excitation energies of interacting fermions. The detailed formalism is provided for two-dimensional multiorbital systems and a benchmark calculation is performed for the two-dimensional single-band Hubbard model. The method can be adapted straightforwardly to symmetry-broken states, three-dimensional systems, and finite-temperature calculations. [ABSTRACT FROM AUTHOR]

We theoretically study the magnetization inside a normal metal induced in an s-wave superconductor/ferromagnetic metal/normal metal/ferromagnetic metal/s-wave superconductor (S/F1/N/F2/S) Josephson junction. Using the quasiclassical Green's function method, we show that the magnetization becomes finite inside the N. The origin of this magnetization is due to odd-frequency spin-triplet Cooper pairs formed by electrons of equal and opposite spins, which are induced by the proximity effect in the S/F1/N/F2/S junction. We find that the magnetization M(d,θ) in the N can be decomposed into two parts, M(d,θ) = MI(d) + MII(d,θ), where θ is the superconducting phase difference between the two Ss and d is the thickness of N. The θ-independent magnetization MI(d) exists generally in S/F junctions, while MII(d,θ) carries all θ dependence and represents the fingerprint of the phase coherence between the two Ss in Josephson junctions. The θ dependence thus allows us to control the magnetization in the N by tuning θ for a fixed d. We show that the θ-independent magnetization MI(d) weakly decreases with increasing d, while the θ-dependent magnetization MII(d,θ) rapidly decays with d. Moreover, we find that the time-averaged magnetization 〈MII(d,θ)㊧ exhibits a discontinuous peak at each resonance dc voltage Vn=nħωS/2e (n: integer) when dc voltage V as well as ac voltage vac(t) with frequency ωS are both applied to the S/F1/N/F2/S junction. This is because MII(d,θ) oscillates generally in time t (ac magnetization) with dθ/dt=2e[V+vac(t)]/ħ and thus 〈MII(d,θ)〉 = 0, but can be converted into the time-independent dc magnetization for the dc voltage at Vn. We also discuss that the magnetization induced in the N can be measurably large in realistic systems. Therefore, the measurement of the induced magnetization serves as an alternative way to detect the phase coherence between the two Ss in Josephson junctions. Our results also provide a basic concept for tunable magnetization in superconducting spintronics devices. [ABSTRACT FROM AUTHOR]

The observation of a high-mobility two-dimensional electron gas between two insulating complex oxides, especially LaAlO3/SrTiO3, has enhanced the potential of oxides for electronics. The occurrence of this conductivity is believed to be driven by polarization discontinuity, leading to an electronic reconstruction. In this scenario, the crystal orientation has an important role and no conductivity would be expected, for example, for the interface between LaAlO3 and (110)-oriented SrTiO3, which should not have a polarization discontinuity. Here we report the observation of unexpected conductivity at the LaAlO3/SrTiO3 interface prepared on (110)-oriented SrTiO3, with a LaAlO3-layer thickness-dependent metal-insulator transition. Density functional theory calculation reveals that electronic reconstruction, and thus conductivity, is still possible at this (110) interface by considering the energetically favourable (110) interface structure, that is, buckled TiO2/LaO, in which the polarization discontinuity is still present. The conductivity was further found to be strongly anisotropic along the different crystallographic directions with potential for anisotropic superconductivity and magnetism, leading to possible new physics and applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • The electronic and catalytic properties of group 15 clusters are studied using DFT. • Sp-and sp3-hybridized gases adsorbed physically while sp2-ones adsorbed chemically. • The clusters are semiconductors with band gaps (2.1−3 eV) tunable by the adsorption. • The overpotential (η) for oxygen evolution on the edges is lower than on the surface. • Sb-cluster has the lowest η, 0.31 v, due to moderate bonding with all intermediates. Density functional theory calculations are employed to investigate the electronic, adsorption, and catalytic properties of Bi-, Sb-, and As-nanoclusters. The stability of these clusters are confirmed by the obtained positive binding energies, the change in the free energy, and frequencies, also they can be grown on different substrates such as graphene and hexagonal boron nitride. They have energy gaps ranging from 2.1 to 3 eV that can be controlled by adsorption of different gases or molecules, for instance, adsorption of C 2 decreases the gap in Sb-18-a cluster from 2.7 eV to 0.8 eV. These clusters show also interesting adsorption properties where some gases are physically adsorbed (like, N2 and CH 4) while others are chemically adsorbed (O 2 and SO 2). In the first case, the linear N 2 molecule has a strong triple bond, from the sp-hybridization, that can't be broken through the interaction with the clusters, the same occurs also for the sp3-hybridized CH 4 with the strong sigma bonds. For the sp2-hybridized O 2 molecule, one of the relatively weaker double bond can be broken through the interaction to form another with the cluster. The oxygen evolution reaction (OER) on the edges of these clusters requires lower overpotential than their surfaces due to the moderate adsorption of O by one edge atom with respect to the strong adsorption by two surface atoms. Nanoclusters and quantum dots of Sb provide the best values for the overpotential due to moderate bonding that Sb atoms form with all intermediates not only O, namely overpotentials equal 0.31 and 0.39 V for the nanocluster and the quantum dots, respectively. This significant enhancement of the OER activity makes such clusters strong applicants for water oxidation catalysts. [ABSTRACT FROM AUTHOR]

Electric-field controlled exchange bias in a heterostructure composed of the ferromagnetic manganite La0.7Sr0.3MO3 and the ferroelectric antiferromagnetic BiFeO3 has recently been demonstrated experimentally. By means of a model Hamiltonian, we provide a possible explanation for the origin of this magnetoelectric coupling. We find, in agreement with experimental results, a net ferromagnetic moment at the BiFeO3 interface. The induced ferromagnetic moment is the result of the competition between the eg-electron double exchange and the t2g-spin antiferromagnetic superexchange that dominates in bulk BiFeO3. The balance of these simultaneous ferromagnetic and antiferromagnetic tendencies is strongly affected by the interfacial electronic charge density, which, in turn, can be controlled by the BiFeO3 ferroelectric polarization. [ABSTRACT FROM AUTHOR]

The perovskite SrIrO3 is an exotic narrow-band metal owing to a confluence of the strengths of the spin-orbit coupling (SOC) and the electron-electron correlations. It has been proposed that topological and magnetic insulating phases can be achieved by tuning the SOC, Hubbard interactions, and/or lattice symmetry. Here, we report that the substitution of nonmagnetic, isovalent Sn4+ for Ir4+ in the SrIr1-xSnxO3 perovskites synthesized under high pressure leads to a metal-insulator transition to an antiferromagnetic (AF) phase at TN=225 K. The continuous change of the cell volume as detected by x-ray diffraction and the κ-shape transition of the specific heat on cooling through TN demonstrate that the metal-insulator transition is of second order. Neutron powder diffraction results indicate that the Sn substitution enlarges an octahedral-site distortion that reduces the SOC relative to the spin-spin exchange interaction and results in the type-G AF spin ordering below TN. Measurement of high-temperature magnetic susceptibility shows the evolution of magnetic coupling in the paramagnetic phase typical of weak itinerant-electron magnetism in the Sn-substituted samples. A reduced structural symmetry in the magnetically ordered phase leads to an electron gap opening at the Brillouin zone boundary below TN in the same way as proposed by Slater. [ABSTRACT FROM AUTHOR]

In this study, we systematically investigate three-dimensional (3D) momentum (ℏk)-resolved electronic structures of Ruddlesden-Popper-type iridium oxides Srn+1IrnO3n+1 using soft-x-ray (SX) angle-resolved photoemission spectroscopy (ARPES). Our results provide direct evidence of an insulator-to-metal transition that occurs upon increasing the dimensionality of the IrO2-plane structure. This transition occurs when the spin-orbit-coupled jeff=1/2 band changes its behavior in the dispersion relation and moves across the Fermi energy. In addition, an emerging band along the Γ(0,0,0)-R(π,π,π) direction is found to play a crucial role in the metallic characteristics of SrIrO3. By scanning the photon energy over 350 eV, we reveal the 3D Fermi surface in SrIrO3 and kz-dependent oscillations of photoelectron intensity in Sr3Ir2O7. In contrast to previously reported results obtained using low-energy photons, folded bands derived from lattice distortions and/or magnetic ordering make significantly weak (but finite) contributions to the k-resolved photoemission spectrum. At the first glance, this leads to the ambiguous result that the observed k-space topology is consistent with the unfolded Brillouin zone (BZ) picture derived from a nonrealistic simple square or cubic Ir lattice. Through careful analysis, we determine that a superposition of the folded and unfolded band structures has been observed in the ARPES spectra obtained using photons in both ultraviolet and SX regions. To corroborate the physics deduced using low-energy ARPES studies, we propose to utilize SX-ARPES as a powerful complementary technique, as this method surveys more than one whole BZ and provides a panoramic view of electronic structures. [ABSTRACT FROM AUTHOR]

The coexistence of valley polarization and topology has considerably facilitated the applications of 2D materials toward valleytronics device technology. However, isolated and distinct valleys are required to observe the valley-related quantum phenomenon. Herein, we report a new mechanism to generate in-plane magnetization direction-dependent isolated valley carriers by preserving or breaking the mirror symmetry in a 2D system. First-principle calculations are carried out on a prototype material, W 2 MnC 2 O 2 MXene, to demonstrate the mechanism. A valley-coupled topological phase transition among Weyl semimetal, valley-polarized quantum anomalous Hall insulator, and topological semimetal is observed by manipulating the in-plane magnetization directions in W 2 MnC 2 O 2 . Monte Carlo simulations of W 2 MnC 2 O 2 show that the estimated Curie temperature is around 170 K, indicating the possibility of observing valley-polarized topological states at higher temperatures. Our finding provides a generalized platform for investigating the valley and topological physics, which is extremely important for future quantum information processing applications.

Bundles of engineered collagen microfibers are promising synthetic tendons as substitutes for autogenous grafts. The purpose of this study was to develop high-speed and continuous spinning of collagen microfibers that involves stretching of collagen stream. Our study revealed the 'critical fibrillogenesis concentration (CFC)' of neutralized collagen solutions, which is defined as the upper limit of the collagen concentration at which neutralized collagen molecules remain stable as long as they are cooled (⩽10 °C). Neutralized collagen solutions at collagen concentrations slightly below the CFC formed cord-like collagen gels comprising longitudinally aligned fibrils when extruded from nozzles into an ethanol bath. Dry collagen microfibers with a controlled diameter ranging from 122 ± 2-31.2 ± 1.7 μm can be spun from the cord-like gels using nozzles of various sizes. The spinning process was improved by including stretching of collagen stream to further reduce diameter and increase linear velocity. We extruded a collagen solution through a 182 μm diameter nozzle while simultaneously stretching it in an ethanol bath during gelation and fiber formation. This process resembles the stretching of a melted thermoplastic resin because it solidifies during melt spinning. The mechanical properties of the stretched collagen microfibers were comparable to the highest literature values obtained using microfluidic wet spinning, as they exhibited longitudinally aligned fibrils both on their surface and in their core. Previous wet spinning methods were unable to generate collagen microfibers with a consistent tendon-like fibrillar arrangement throughout the samples. Although the tangent modulus (137 ± 7 MPa) and stress at break of the swollen bundles of stretched microfibers (13.8 ± 1.9 MPa) were lower than those of human anterior cruciate ligament, they were within the same order of magnitude. We developed a spinning technique that produces narrow collagen microfibers with a tendon-like arrangement that can serve as artificial fiber units for collagen-based synthetic tendons., (© 2024 IOP Publishing Ltd.)

Objective: This study evaluated the effect of pressure injury (PI) prophylactic dressings used for patients at high risk of PI development to reduce friction, shear force and pressure, and their combined force, in an original polymer-based skin model., Method: A low-friction outer-layer hydrocolloid (LFH) dressing and a multilayered silicone foam (MSF) dressing were used. Before application, compression and friction properties were measured. Our original experimental model-the 'simulated skin-shearing test'-consisted of: a weight; a polyurethane-based skin model containing a three-axis tactile sensor; dressings; a table covered with bedsheets; and a mechanical tester, by which the interface friction force, internal shear force and pressure were measured continuously during skin model movements. An estimated combined force generated by internal shear and pressure was represented as a vector. A model with no dressing was used as a control., Results: The LFH dressing had significantly higher compression strength versus the MSF dressing. In contrast, the dynamic coefficient of friction was lower for the LFH dressing versus the MSF dressing (p<0.05). In simulated skin-shearing test results, shear forces were 0.45N and 0.42N for LFH and MSF dressings, respectively, with no significant difference. The estimated combined force was lower for the MSF dressing compared with that of the LFH dressing and control., Conclusion: The shear force-reducing effect in the skin model was equivalent between the LFH and MSF dressings. However, the MSF dressing significantly reduced the force generated by a combination of internal shear force and pressure compared with the LFH dressing.

To demonstrate the feasibility of plasticizer-gelatin solutions as novel skin protection materials from a physical aspect, we evaluated the rheological properties of the solutions and the mechanical properties and textures of their dried sheets and films. Three types of sugars and polyols were employed as organic plasticizers and mixed with gelatin in solutions at plasticizer/gelatin weight ratios of 0.13-1.67. The plasticizers minimally affected the viscosities and gelation temperatures of the gelatin solutions, but they remarkably softened dried gelatin sheets, except for propylene glycol. Glycerol exhibited the best plasticizing effects, but the sheets obtained using glycerol showed tacky textures. Preliminary investigations on the film-forming properties of the solutions on the human skin showed that the fructose-gelatin solution at a weight ratio of 1.0 formed a flexible thin film with a texture and mechanical properties similar to those of a commercially available polyurethane-based flexible film dressing. In terms of physical properties, we conclude that the fructose-gelatin solution has potential as a skin protection material that transforms from a solution to a film on the skin., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Shunji Yunoki reports financial support was provided by 10.13039/100009619Japan Agency for Medical Research and Development. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors. Published by Elsevier Ltd.)