Molecular species profiles of plasma ceramides in different clinical types of X-linked adrenoleukodystrophy.

X-linked adrenoleukodystrophy (X-ALD) is a genetic disorder associated with peroxisomal dysfunction. Patients with this rare disease accumulate very long-chain fatty acids (VLCFAs) in their bodies because of impairment of peroxisomal VLCFA ?-oxidation. Several clinical types of X-ALD, ranging from mild (axonopathy in the spinal cord) to severe (cerebral demyelination), are known. However, the molecular basis for this phenotypic variability remains largely unknown. In this study, we determined plasma ceramide (CER) profile using liquid chromatography-tandem mass spectrometry. We characterized the molecular species profile of CER in the plasma of patients with mild (adrenomyeloneuropathy;AMN) and severe (cerebral) X-ALD. Eleven X-ALD patients (five cerebral, five AMN, and one carrier) and 10 healthy volunteers participated in this study. Elevation of C26:0 CER was found to be a common feature regardless of the clinical types. The level of C26:1 CER was significantly higher in AMN but not in cerebral type, than that in healthy controls. The C26:1 CER level in the cerebral type was significantly lower than that in the AMN type. These results suggest that a high level of C26:0 CER, along with a control level of C26:1 CER, is a characteristic feature of the cerebral type X-ALD. J. Med. Invest. 70 : 403-410, August, 2023.

Orientation Control of a Two-Dimensional Conductive Metal-Organic Framework Thin Film by a Pyridine Vapor-Assisted Dry Process.

Metal-organic frameworks (MOFs) are attractive materials with periodic pore structures constructed by coordinating metal ions and organic ligands. Recently, Cu3(HHTP)2 (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene), a two-dimensional conductive MOF, has attracted attention as a promising device material. Owing to the anisotropy of Cu3(HHTP)2 properties, oriented thin films of this MOF are desired for evaluating its physical properties and device integration. To date, wet processes have been used to fabricate Cu3(HHTP)2 films, whereas dry processes are essential for high-quality devices. However, oriented Cu3(HHTP)2 thin films have not yet been fabricated by using dry processes. In this study, we succeed in fabricating an orientation-controlled Cu3(HHTP)2 film on Al2O3 (001) by using a two-step dry process involving (1) the multilayer deposition of copper acetate and HHTP using a vapor deposition system and (2) pyridine vapor-assisted annealing. In-plane and out-of-plane X-ray diffraction patterns confirm the successful fabrication of the (001)-oriented Cu3(HHTP)2 films. The conductivity evaluated by four-probe measurements is 2.6 × 10-2 S cm-1, comparable to that of films fabricated by wet processes. This study provides a novel guideline for the orientation control of two-dimensional conductive MOF thin films via a dry process.

Purification and Characterization of the Lecithin-Dependent Thermolabile Hemolysin Vhe1 from the Vibrio sp. Strain MA3 Associated with Mass Mortality of Pearl Oyster (Pinctada fucata).

In a previous study, we isolated a Vibrio sp. strain MA3 and its virulence factor, a hemolysin encoded by vhe1. This strain is associated with mass mortalities of the pearl oyster Pinctada fucata. In the present study, the vhe1 gene from strain MA3 was cloned and its encoded product was purified and characterized. Our results show that the vhe1 gene encodes a protein of 417 amino acids with an estimated molecular mass of 47.2 kDa and a pI of 5.14. The deduced protein, Vhe1, was found to contain the conserved amino acid sequence (GDSL motif) of the hydrolase/esterase superfamily and five conserved blocks characteristic of SGNH hydrolases. A BLAST homology search indicated that Vhe1 belongs the lecithin-dependent hemolysin/thermolabile hemolysin (LDH/TLH) family. In activity analyses, the optimal temperature for both the hemolytic and phospholipase activities of Vhe1 was 50 °C. Vhe1 hemolytic activity and phospholipase activity were highest at pH 8.5 and pH 8.0, respectively. However, both enzymatic activities sharply decreased at high temperature (> 50 °C) and pH < 7.0. Compared with previously reported hemolysins, Vhe1 appeared to be more thermal- and pH-labile. Both its hemolytic activity and phospholipase activity were significantly inhibited by CuCl2, CdCl2, ZnCl2, and NiCl2, and slightly inhibited by MnCl2 and CoCl2. Vhe1 showed higher phospholipase activity toward medium-chain fatty acids (C8-C12) than toward shorter- and longer-chain fatty acids. These results accumulate knowledge about the LDH/TLH of V. alginolyticus, which detailed characterization has not been reported, and contribute to solving of the mass mortality of pearl oyster.

Impulsivity and Alcohol-Drinking Behavior: Evidence from Japan.

Despite the attempt by the Japanese government to reduce alcohol consumption, reduction of alcohol consumption requires improvement. We explore this issue from the impulsivity perspective and investigate whether a causal relationship exists between impulsivity and drinking behavior. We used data from the Preference Parameter Study of Osaka University to capture respondents' drinking status. Our probit regression showed that procrastination, a proxy measure of impulsivity, was significantly associated with drinking behavior, while hyperbolic discounting, a direct measure of impulsivity, was insignificant. Our findings suggest that impulsive people will discount their health in the future; thus, the government should consider impulsivity in policymaking. For example, awareness programs should focus more on future healthcare costs from alcohol-related problems so that impulsive drinkers can understand how much they may need to spend in the future compared to current satisfaction with alcohol drinking.

Selective Epitaxial Growth of Ca2NH and CaNH Thin Films by Reactive Magnetron Sputtering under Hydrogen Partial Pressure Control.

Calcium compounds with N and H are promising catalysts for NH3 conversion, and their epitaxial thin films provide a platform to quantitatively understand the catalytic activities. Here we report the selective epitaxial growth of Ca2NH and CaNH thin films by controlling the hydrogen partial pressure (PH2) during reactive magnetron sputtering. We find that the hydrogen charge states can be tuned by PH2: Ca2NH containing H- is formed at PH2 < 0.04 Pa, while CaNH containing H+ is formed at PH2 > 0.04 Pa. In situ plasma emission spectroscopy reveals that the intensity of the Ca atomic emission (∼422 nm) decreases as PH2 increases, suggesting that Ca reacts with H2 and N2 to form Ca2NH at lower PH2, whereas at higher PH2, CaHx is first formed on the target surface and then sputtered to produce CaNH. This study provides a novel route to control the hydrogen charge states in Ca-N-H epitaxial thin films.

Immense Reduction in Interfacial Resistance between Sulfide Electrolyte and Positive Electrode.

Low interfacial resistance between the solid sulfide electrolyte and the electrode is critical for developing all-solid-state Li batteries; however, the origin of interfacial resistance has not been quantitatively reported in the literature. This study reports the resistance values across the interface between an amorphous Li3PS4 solid electrolyte and a LiCoO2(001) epitaxial thin film electrode in a thin-film Li battery model. High interfacial resistance is observed, which is attributed to the spontaneous formation of an interfacial layer between the solid electrolyte and the positive electrode upon contact. That is, the interfacial resistance originates from an interphase mixed layer instead of a space charge layer. The introduction of a 10 nm thick Li3PO4 buffer layer between the solid electrolyte and positive electrode layers suppresses the formation of the interphase mixed layer, thereby leading to a 2800-fold decrease in the interfacial resistance. These results provide insight into reducing the interfacial resistance of all-solid-state Li batteries with sulfide electrolytes by utilizing buffer layers.

Drastic Reduction of the Solid Electrolyte-Electrode Interface Resistance via Annealing in Battery Form.

The origin of electrical resistance at the interface between the positive electrode and solid electrolyte of an all-solid-state Li battery has not been fully determined. It is well known that the interface resistance increases when the electrode surface is exposed to air. However, an effective method of reducing this resistance has not been developed. This report demonstrates that drastic reduction of the resistance is achievable by annealing the entire battery cell. Exposing the LiCoO2 positive electrode surface to H2O vapor increases the resistance by more than 10 times (to greater than 136 Ω cm2). The magnitude can be reduced to the initial value (10.3 Ω cm2) by annealing the sample in a battery form. First-principles calculations reveal that the protons incorporated into the LiCoO2 structure are spontaneously deintercalated during annealing to restore the low-resistance interface. These results provide fundamental insights into the fabrication of high-performance all-solid-state Li batteries.

Ionic Rectification across Ionic and Mixed Conductor Interfaces.

In electrochemical devices, it is important to control the ionic transport between the electrodes and solid electrolytes. However, it is difficult to tune the transport without applying an electric field. This paper presents a method to modulate the transport via tuning of the electrochemical potential difference by controlling the electronic states at the interfaces. We fabricated thin-film solid-state Li batteries using LiTi2O4 thin films as positive electrodes. The spontaneous Li-ion transport between the solid electrolyte and LiTi2O4 is controlled by tuning the electrochemical potential difference via use of an electrically conducting Nb-doped SrTiO3 substrate. This study establishes the foundation for rectifying the ionic transport via electronic energy band alignment.

Relaxation of the Interface Resistance between Solid Electrolyte and 5 V-Class Positive Electrode.

Solid-state Li batteries using 5 V-class positive electrode materials display a higher energy density. However, the high resistance at the interface of the electrolyte and positive electrode (interface resistance, Ri) hinders their practical applications. Here, we report the relaxation of Ri between a solid electrolyte (Li3PO4) and a 5 V-class electrode (LiCo0.5Mn1.5O4). Although Ri is small at the Mn3+/4+ redox voltage of 4.0 V vs Li/Li+ (11 Ω cm2), it rapidly increases by more than 2 orders of magnitude as the voltage increases above the Co3+/4+ redox voltage of 5.2 V vs Li/Li+. After the applied voltage is reduced to 4.0 V vs Li/Li+, Ri decays to the original value after 3 h. The relaxation of Ri after exposure to high voltages suggests that the increase in Ri above 5 V vs Li/Li+ is attributable to the formation of an interfacial layer at the LPO/LCMO interface.

Tuning the Schottky Barrier Height at the Interfaces of Metals and Mixed Conductors.

Understanding electronic and ionic transport across interfaces is crucial for designing high-performance electric devices. The adjustment of work functions is critical for band alignment at the interfaces of metals and semiconductors. However, the electronic structures at the interfaces of metals and mixed conductors, which conduct both electrons and ions, remain poorly understood. This study reveals that a Schottky barrier is present at the interface of the Nb-doped SrTiO3 metal and a LiCoO2 mixed conductor and that the interfacial resistance can be tuned by inserting an electric dipole layer. The interfacial resistance significantly decreased (by more than 5 orders of magnitude) upon the insertion of a 1 nm thick insulating LaAlO3 layer at the interface. We apply these techniques to solid-state lithium batteries and demonstrate that tuning the electronic energy band alignment by interfacial engineering is applicable to the interfaces of metals and mixed conductors. These results highlight the importance of designing positive electrode and current collector interfaces for solid-state lithium batteries with high power density.

Clean Solid-Electrolyte/Electrode Interfaces Double the Capacity of Solid-State Lithium Batteries.

Solid-state lithium (Li) batteries using spinel-oxide electrode materials such as LiNi0.5Mn1.5O4 are promising power supplies for mobile devices and electric vehicles. Here, we demonstrate stable battery cycling between the Li0Ni0.5Mn1.5O4 and Li2Ni0.5Mn1.5O4 phases with working voltages of approximately 2.9 and 4.7 V versus Li/Li+ in solid-state Li batteries with contamination-free clean Li3PO4/LiNi0.5Mn1.5O4 interfaces. This clean interface has the effect of doubling the capacity of conventional battery cycling between the Li0Ni0.5Mn1.5O4 and Li1Ni0.5Mn1.5O4 phases. We also investigated the structural changes between the Li0Ni0.5Mn1.5O4 and Li2Ni0.5Mn1.5O4 phases during battery cycling. Furthermore, we found an inhomogeneous distribution of the Li2Ni0.5Mn1.5O4 phase in the LiNi0.5Mn1.5O4 electrode, induced by spontaneous Li migration after the formation of the Li3PO4/LiNi0.5Mn1.5O4 interface. These results indicate that the formation of a contamination-free clean Li3PO4/LiNi0.5Mn1.5O4 interface is key to increase the battery capacity.

Impact of Surface Roughness on Recrystallization of an α-Al2O3(001) Single Crystal to α-AlO(OH) Diaspore Microcrystals.

We demonstrate that the surface of an α-Al2O3(001) single crystal recrystallizes to α-AlO(OH) under ultrahigh pressure (8 GPa) at 600 °C. The recrystallization depends on the degree of surface roughness. A polished surface topotaxially recrystallizes to (100)-oriented α-AlO(OH) microcrystals, while unpolished surface recrystallizes to polycrystalline α-AlO(OH). This study demonstrates a new synthetic route to obtain oriented crystals of ultrahigh-pressure-phase materials and paves the way for the investigations of the physical and chemical properties of such materials.

Interfacial Superconductivity in FeSe Ultrathin Films on SrTiO_{3} Probed by In Situ Independently Driven Four-Point-Probe Measurements.

We investigated the superconducting transport properties of the one-unit-cell FeSe ultrathin films epitaxially grown on undoped SrTiO_{3}(001) (STO) with a well-defined surface structure by in situ independently-driven four-point-probe measurements. Our results unambiguously revealed the detection of the two-dimensional electrical conduction of the films without parallel conduction through the underlying substrate, both in the normal and superconducting states. The monolayer film exhibited a superconducting transition at an onset temperature of 40 K. Surprisingly, the onset of superconductivity was constantly observed at 40 K even for three- and five-unit-cell-thick FeSe films, even though the normal resistivity decreased with increasing thickness. These results agree with the picture of the interfacial superconductivity, where only the FeSe/STO interface and/or the adjacent first layer of FeSe becomes superconducting while the upper layers stay in the normal metallic state. The observed T_{c} is much lower than that reported by a previous in situ transport measurement for FeSe/Nb:STO but consistent with the results obtained by ex situ measurements for FeSe-undoped STO with a capping layer. This suggests that the capping layer is not an essential factor to limit T_{c}. We rather propose that the charge transfer from the doped substrate has a key role to achieve the higher temperature superconductivity in the one-unit-cell FeSe.

In vivo monitoring of bone microstructure by propagation-based phase-contrast computed tomography using monochromatic synchrotron light.

Hard X-ray phase-contrast imaging is sensitive to density variation in objects and shows a dose advantage for in vivo observation over absorption-contrast imaging. We examined the capability of propagation-based phase-contrast tomography (PB-PCT) with single-distance phase retrieval for tracking of bone structure and mineral changes using monochromatic synchrotron light. Female mice underwent ovariectomy and drill-hole surgery in the right tibial diaphysis and were divided into two groups: OVX and OVX-E (n = 6 each); the latter group was treated with intraperitoneal administration of 14,15-epoxyeicosatrienoic acid (14,15-EET) for promoting bone repair. Age-matched mice subjected to sham ovariectomy and drill-hole surgery (Sham) were also prepared (n = 6). In vivo CT scans of the drilled defect were acquired 3, 7, and 11 days after surgery, and tomographic images were matched by three-dimensional registration between successive time points for monitoring the process of defect filling. In addition, using absorption-contrast CT as the reference method, the validity of PB-PCT was evaluated in one mouse by comparing images of tibial metaphyseal bone between the two methods in terms of bone geometry as well as the measure of mineralization. Although phase retrieval is strictly valid only for single-material objects, PB-PCT, with its lower radiation dose, could provide a depiction of bone structure similar to that from absorption-contrast CT. There was a significant correlation of linear absorption coefficients between the two methods, indicating the possibility of a rough estimate of the measure of mineralization by PB-PCT. Indeed, delayed bone regeneration (OVX vs. Sham) and the efficacy of 14,15-EET for improving osteoporotic bone repair (OVX-E vs. OVX) could be detected in both bone volume and mineralization by PB-PCT. Thus, in combination with single-distance phase retrieval, PB-PCT would have great potential for providing a valuable tool to track changes in bone structure and mineralization, and for evaluating the effects of therapeutic interventions as well.

Low-Energy-Consumption Three-Valued Memory Device Inspired by Solid-State Batteries.

We report the creation of a low-energy-consumption three-valued memory device based on the switching of open-circuit voltages. This device consists of a stack of Li, Li3PO4 solid electrolyte, and Ni electrode films. We observed reversible voltage switching between high, intermediate, and low open-circuit voltages. According to the scaling law, the energy required to switch a device is estimated to be 8.8 × 10-11 J/µm2 and this value is almost 1/50 of that of a typical dynamic random access memory. Both the high- and low-voltage states converged to the intermediate-voltage state, indicating that the intermediate-voltage state is the most stable metastable state.

Epitaxial Growth of Single-Phase Magnesium Dihydride Thin Films.

We describe the epitaxial growth process of single-phase magnesium dihydride (MgH2) thin films on MgO(100) substrates, achieved by reactive magnetron sputtering. We find that direct growth at substrate temperatures higher than 100 °C leads to partial MgH2 decomposition to Mg, hindering single-phase epitaxy of MgH2. To improve the crystallinity and suppress the decomposition of Mg, we optimize MgH2 growth using a two-step process, consisting of (1) precursor growth at room temperature and (2) postdeposition annealing at 380 °C, under a pressure of 1.0 × 105 Pa with H2 (4%)/Ar (96%) premixed gases. Using this two-step process, we obtain single-phase MgH2 epitaxial films with high crystallinity, transparency, and resistivity. Further, the application of this method to grow MgH2 thin films on different MgF2 and Al2O3 substrates enables us to use the epitaxial effects to control the growth orientation of MgH2 thin films; we show that MgH2(100) and MgH2(001) epitaxial thin films can be grown on Al2O3(001) and MgF2(001) substrates, respectively.

Gut microbial metabolites of linoleic acid are metabolized by accelerated peroxisomal ß-oxidation in mammalian cells.

Microorganisms in animal gut produce unusual fatty acids from the ingested diet. Two types of hydroxy fatty acids (HFAs), 10-hydroxy-cis-12-octadecenoic acid (HYA) and 10-hydroxy-octadecanoic acid (HYB), are linoleic acid (LA) metabolites produced by Lactobacillus plantarum. In this study, we investigated the metabolism of these HFAs in mammalian cells. When Chinese hamster ovary (CHO) cells were cultured with HYA, approximately 50% of the supplemented HYA disappeared from the dish within 24 h. On the other hand, the amount of HYA that disappeared from the dish of peroxisome (PEX)-deficient CHO cells was lower than 20%. Significant amounts of C2- and C4-chain-shortened metabolites of HYA were detected in culture medium of HYA-supplemented CHO cells, but not in medium of PEX-deficient cells. These results suggested that peroxisomal ß-oxidation is involved in the disappearance of HYA. The PEX-dependent disappearance was observed in the experiment with HYB, but not with LA. We also found that HYA treatment up-regulates peroxisomal ß-oxidation activity of human gastric MKN74 cells and intestinal Caco-2 cells. These results indicate a possibility that HFAs produced from gut bacteria affect lipid metabolism of host via modulation of peroxisomal ß-oxidation activity.

Atomically Well-Ordered Structure at Solid Electrolyte and Electrode Interface Reduces the Interfacial Resistance.

Using synchrotron surface X-ray diffraction, we investigated the atomic structures of the interfaces of a solid electrolyte (Li3PO4) and electrode (LiCoO2). We prepared two types of interfaces with high and low interface resistances; the low-resistance interface exhibited a flat and well-ordered atomic arrangement at the electrode surface, whereas the high-resistance interface showed a disordered interface. These results indicate that the crystallinity of LiCoO2 at the interface has a significant impact on interface resistance. Furthermore, we reveal that the migration of Li ions along the interface and into grain boundaries and antiphase domain boundaries is a critical factor reducing interface resistance.

Extremely Low Resistance of Li3PO4 Electrolyte/Li(Ni0.5Mn1.5)O4 Electrode Interfaces.

Solid-state Li batteries containing Li(Ni0.5Mn1.5)O4 as a 5 V-class positive electrode are expected to revolutionize mobile devices and electric vehicles. However, practical applications of such batteries are hampered by the high resistance at their solid electrolyte/electrode interfaces. Here, we achieved an extremely low electrolyte/electrode interface resistance of 7.6 Ω cm2 in solid-state Li batteries with Li(Ni0.5Mn1.5)O4. Furthermore, we observed spontaneous migration of Li ions from the solid electrolyte to the positive electrode after the formation of the electrolyte/electrode interface. Finally, we demonstrated stable fast charging and discharging of the solid-state Li batteries at a current density of 14 mA/cm2. These results provide a solid foundation to understand and fabricate low-resistance electrolyte/electrode interfaces.

Atomic-scale visualization of oxide thin-film surfaces.

The interfaces of complex oxide heterostructures exhibit intriguing phenomena not observed in their constituent materials. The oxide thin-film growth of such heterostructures has been successfully controlled with unit-cell precision; however, atomic-scale understandings of oxide thin-film surfaces and interfaces have remained insufficient. We examined, with atomic precision, the surface and electronic structures of oxide thin films and their growth processes using low-temperature scanning tunneling microscopy. Our results reveal that oxide thin-film surface structures are complicated in contrast to the general perception and that atomically ordered surfaces can be achieved with careful attention to the surface preparation. Such atomically ordered oxide thin-film surfaces offer great opportunities not only for investigating the microscopic origins of interfacial phenomena but also for exploring new surface phenomena and for studying the electronic states of complex oxides that are inaccessible using bulk samples.