電動パワーステアリングにおける振動抑制制御の単純化と操舵力推定の高精度化に関する研究

学位記番号：理工博甲2

Electrochemical Surface Analysis of LiMn₂O₄ Thin-film Electrodes in LiPF6/Propylene Carbonate at Room and Elevated Temperatures

Degradation of LiMn₂O₄ in LiPF₆-based electrolyte solution is complicated due to the influence of PF₆⁻ anion. Decomposition of PF₆⁻ anion accelerates both of dissolution of manganese ion and surface-film formation. In this study, surface states of LiMn₂O₄ thin-film electrodes in LiPF6/propylene carbonate (PC) derived from the surface-film formation were investigated using redox reaction of ferrocene and spectroscopic analyses. The spectroscopic analyses suggested that properties of the surface film depended the operation temperature (30°C and 55°C); a thinner surface film composed of LiF and PC decomposition products formed on LiMn₂O₄ at 30°C and a thicker surface film was formed at 55°C. The redox reaction of ferrocene clearly showed that LiMn₂O₄ was completely passivated at 30°C, while it was partially passivated at 55°C, indicating the surface film formed at 55°C was not compact and LiMn₂O₄ was exposed to the electrolyte solution. It was one of the causes of the rapid degradation of LiMn₂O₄ at elevated temperatures in LiPF6-based electrolyte solution

Impact of Hydrogen Peroxide on Carbon Corrosion in Aqueous KOH Solution

Impact of hydrogen peroxide on carbon corrosion is investigated by immersion tests of catalyst-deposited highly oriented pyrolytic graphite (HOPG) samples to an aqueous solution of 1.0 mol dm⁻³ KOH + 5 mmol dm⁻³ H₂O₂. The surfaces of the HOPG samples are observed with field-emission scanning electron microscopy and X-ray photoelectron spectroscopy. HOPG without catalyst shows almost no morphological change while the distribution of C-O and C=O functional groups increases. In contrast, Pt-loaded HOPG exhibits the formation of scars and COO functional groups, which shows a relatively severe carbon corrosion reaction resulting in CO₃²⁻ formation. Since the Pt-loaded HOPG after the immersion test to 0.5 mol dm⁻³ H₂SO₄ + 5 mmol dm⁻³ H₂O₂ shows much smaller scars, it can be concluded that hydrogen peroxide corrodes Pt-loaded carbon more severely in the alkaline electrolyte solution than the acid electrolyte solution. Ag-loaded HOPG also shows the scars, while the sizes of scars are much smaller than those on the Pt-loaded HOPG. In contrast, MnOx and CoOx-loaded HOPGs exhibit no scar and minor oxygen-containing functional groups than the HOPG without catalyst, whereas MnOx and CoOx-loaded HOPGs shows larger scars than Pt and Ag-loaded HOPGs after electrochemical carbon corrosion test

Relationship between radiographic grading of osteoarthritis and the biochemical markers for arthritis in knee osteoarthritis

The aim of this study was to investigate the relationship between the biochemical markers of arthritis and the radiographic grading of osteoarthritis (OA) in knees. Seventy-one women aged 49–85 years with knee OA were studied. Anterior–posterior knee radiographs and hand radiographs were taken in all patients. The radiographic grading of OA in the knee was performed by using the Kellgren–Lawrence criteria and the joint space width. The 71 patients with knee OA were divided into two groups: 37 patients exhibiting generalized osteoarthritis (GOA) and 34 non-GOA patients, according to the grading of their hand radiograph. C-reactive protein (CRP), urinary pyridinoline, YKL-40, plasma matrix metalloproteinase (MMP)-3, MMP-9 and tissue inhibitor of metalloproteinases (TIMP)-1 were measured as the biochemical markers of arthritis. The radiographic grading with the Kellgren–Lawrence scale revealed a significant relationship to the joint space width (P = 0.003): the joint space width decreased with increasing Kellgren–Lawrence grade. All biochemical markers had negative correlations with the joint space width, but only urinary pyridinoline had a significant correlation (P = 0.039). Pyridinoline (P = 0.034) and TIMP-1 (P = 0.017) also exhibited a significant relationship to the Kellgren–Lawrence grade. In GOA evaluations, the joint space width did not differ between GOA and non-GOA patients. CRP, pyridinoline, YKL-40 and MMP-3 levels were significantly greater in GOA patients than in non-GOA patients. CRP, pyridinoline, YKL-40, MMP-3 and TIMP-1 levels each related to at least one of the radiographic gradings. Furthermore, pyridinoline related to every type of radiographic grading examined in the present study

Relation between Mixing Processes and Properties of Lithium-ion Battery Electrode-slurry

The mixing process of electrode-slurry plays an important role in the electrode performance of lithium-ion batteries (LIBs). The dispersion state of conductive materials, such as acetylene black (AB), in the electrode-slurry directly influences the electronic conductivity in the composite electrodes. In this study, the relation between the mixing process of electrode-slurry and the internal resistance of the composite electrode was investigated in combination with the characterization of the electrode-slurries by the rheological analysis and the alternating current (AC) impedance spectroscopy. Some of the electrode-slurries showed higher value and gentler slope of the dynamic storage modulus in the low-angular-frequency region and higher thixotropic index than the others depending on the way of the mixing process and the AB content, agreeing with the low electronic volume resistivities of the corresponding composite electrodes and the electrode-slurries, which indicates the AB network growth. The results suggested that the low-viscosity state when AB and active electrode material are mixed contributes to the dispersive AB network. (C) The Author(s) 2021. Published by ECSJ

Kinetic properties of sodium-ion transfer at the interface between graphitic materials and organic electrolyte solutions

Graphitic materials cannot be applied for the negative electrode of sodium-ion battery because the reversible capacities of graphite are anomalously small. To promote electrochemical sodium-ion intercalation into graphitic materials, the interfacial sodium-ion transfer reaction at the interface between graphitized carbon nanosphere (GCNS) electrode and organic electrolyte solutions was investigated. The interfacial lithium-ion transfer reaction was also evaluated for the comparison to the sodium-ion transfer. From the cyclic voltammograms, both lithium-ion and sodium-ion can reversibly intercalate into/from GCNS in all of the electrolytes used here. In the Nyquist plots, the semi-circles at the high frequency region derived from the Solid Electrolyte Interphase (SEI) resistance and the semi-circles at the middle frequency region owing to the charge-transfer resistance appeared. The activation energies of both lithium-ion and sodium-ion transfer resistances were measured. The values of activation energies of the interfacial lithium-ion transfer suggested that the interfacial lithium-ion transfer was influenced by the interaction between lithium-ion and solvents, anions or SEI. The activation energies of the interfacial sodium-ion transfer were larger than the expected values of interfacial sodium-ion transfer based on the week Lewis acidity of sodium-ion. In addition, the activation energies of interfacial sodium-ion transfer in dilute FEC-based electrolytes were smaller than those in concentrated electrolytes. The activation energies of the interfacial lithium/sodium-ion transfer of CNS-1100 in FEC-based electrolyte solutions were almost the same as those of CNS-2900, indicating that the mechanism of interfacial charge-transfer reaction seemed to be the same for highly graphitized materials and low-graphitized materials each other

Sodium/Lithium-Ion Transfer Reaction at the Interface between Low-Crystallized Carbon Nanosphere Electrodes and Organic Electrolytes

Carbon nanosphere (CNS) electrodes are the candidate of sodium-ion battery (SIB) negative electrodes with small internal resistances due to their small particle sizes. Electrochemical properties of low-crystallized CNS electrodes in dilute and concentrated sodium bis(trifluoromethanesulfonyl) amide/ethylene carbonate + dimethyl carbonate (NaTFSA/EC + DMC) were first investigated. From the cyclic voltammograms, both lithium ion and sodium ion can reversibly insert into/from CNSs in all of the electrolytes used here. The cycling stability of CNSs in concentrated electrolytes was better than that in dilute electrolytes for the SIB system. The interfacial charge-transfer resistances at the interface between CNSs and organic electrolytes were evaluated using electrochemical impedance spectroscopy. In the Nyquist plots, the semicircles at the middle-frequency region were assigned to the parallel circuits of charge-transfer resistances and capacitances. The interfacial sodium-ion transfer resistances in concentrated organic electrolytes were much smaller than those in dilute electrolytes, and the rate capability of CNS electrodes in sodium salt-concentrated electrolytes might be better than in dilute electrolytes, suggesting that CNSs with concentrated electrolytes are the candidate of SIB negative electrode materials with high rate capability. The calculated activation energies of interfacial sodium-ion transfer were dependent on electrolyte compositions and similar to those of interfacial lithium-ion transfer

Kinetics of Interfacial Lithium-ion Transfer between a Graphite Negative Electrode and a Li₂S-P₂S₅ Glassy Solid Electrolyte

All-solid-state lithium-ion batteries that use sulfide solid electrolytes have attracted much attention due to their high safety and wide electrochemical window. In this study, highly oriented pyrolytic graphite (HOPG) and 75Li₂S-25P₂S₅ (mol%) glass were used as a model graphite negative electrode and a sulfide solid electrolyte, respectively. Interfacial lithium-ion transfer between 75Li₂S-25P₂S₅ glass and the HOPG electrode was studied by AC impedance spectroscopy measurements. The activation energy of the interfacial lithium-ion transfer was estimated to be around 37 kJ mol⁻¹, which was much smaller than that at the interface between organic liquid electrolytes and HOPG electrode, indicating that the lithium-ion transfer at the interface between 75Li₂S-25P₂S₅ glass and HOPG electrode proceeded quite rapidly. Furthermore, surface deposition of TiO₂ and surface oxidation on HOPG electrodes were performed using the atomic layer deposition (ALD) method. Interfacial lithium-ion transfer between 75Li₂S-25P₂S₅ glass and ALD-modified-HOPG electrodes was also investigated. The activation energies of the interfacial lithium-ion transfer were slightly higher than that of HOPG, but the resistance of the charge-transfer process was lower, indicating that the affinity of the HOPG electrode for the glass electrolyte was improved by surface modification

Photoelectrode characteristics of partially hydrolyzed aluminum phthalocyanine chloride/fullerene C 60 composite nanoparticles working in a water phase

金沢大学先端科学・社会共創推進機構Photoelectrochemical measurements were used to study the photoelectrode characteristics of composite nanoparticles composed of fullerene C 60 and partially hydrolyzed aluminum phthalocyanine chloride (AlPc). In cyclic voltammetry measurements, the electrodes coated with the composite nanoparticles were found to have photoanodic [electron donor: 2-mercaptoethanol (ME)] and photocathodic (electron acceptor: O 2) characteristics similar to those of the vapor-deposited p/n junction electrode. Their photoanodic features were further investigated with respect to the transient photocurrent response to light irradiation and the dependence on ME concentration (under potentiostatic conditions), from which it was noted that there was a decrease in the initial spiky photocathodic current and saturation of the steady-state photoanodic current at a higher ME concentration. Thus, the reaction kinetics was probably dominated by charge transport process. Moreover, external and internal quantum efficiency spectrum measurements indicated that the composite nanoparticles responded to the full spectrum of visible light (<880 nm) for both the photoanodic and photocathodic current. The present research will assist comprehension of photocatalytic behavior of the composite nanoparticles. © 2012 by the authors

Essential functions of the CNOT7/8 catalytic subunits of the CCR4-NOT complex in mRNA regulation and cell viability

Shortening of mRNA poly(A) tails (deadenylation) to trigger their decay is mediated mainly by the CCR4-NOT deadenylase complex. While four catalytic subunits (CNOT6, 6L 7, and 8) have been identified in the mammalian CCR4-NOT complex, their individual biological roles are not fully understood. In this study, we addressed the contribution of CNOT7/8 to viability of primary mouse embryonic fibroblasts (MEFs). We found that MEFs lacking CNOT7/8 expression [Cnot7/8-double knockout (dKO) MEFs] undergo cell death, whereas MEFs lacking CNOT6/6L expression (Cnot6/6l-dKO MEFs) remain viable. Co-immunoprecipitation analyses showed that CNOT6/6L are also absent from the CCR4-NOT complex in Cnot7/8-dKO MEFs. In contrast, either CNOT7 or CNOT8 still interacts with other subunits in the CCR4-NOT complex in Cnot6/6l-dKO MEFs. Exogenous expression of a CNOT7 mutant lacking catalytic activity in Cnot7/8-dKO MEFs cannot recover cell viability, even though CNOT6/6L exists to some extent in the CCR4-NOT complex, confirming that CNOT7/8 is essential for viability. Bulk poly(A) tail analysis revealed that mRNAs with longer poly(A) tails are more numerous in Cnot7/8-dKO MEFs than in Cnot6/6l-dKO MEFs. Consistent with elongated poly(A) tails, more mRNAs are upregulated and stabilized in Cnot7/8-dKO MEFs than in Cnot6/6l-dKO MEFs. Importantly, Cnot6/6l-dKO mice are viable and grow normally to adulthood. Taken together, the CNOT7/8 catalytic subunits are essential for deadenylation, which is necessary to maintain cell viability, whereas CNOT6/6L are not