Electrical conductivity of LiClO 4 solution in binary solvent of propylene carbonate (PC) and 1,2-dimethoxyethane (DME) coexisting with LiCoO 2 powder was measured. Maximum value of conductivity in LiClO 4 /PC-DME solution observed at ca. 1:1 of volume fraction shifted toward lower content of DME. In higher LiClO 4 concentration reached to 3 mol L −1 , the conductivity of LiClO 4-PC 1−x DME x increased with DME content even if LiCoO 2 was added. The results of FT-IR measurement support the results of conductivity measurement for PC solvation of the slurry sample of LiCoO 2 /LiClO 4 /PC-DME system.

Solution structures at solid–liquid interfaces play important roles in electrochemical reaction systems. To gain insights into interactions between binary solutions and metal oxides, we used quantitative 1H NMR and resonance shear measurements to investigate the behavior of a mixed solvent of propylene carbonate (PC)–1,2-dimethoxyethane (DME) at the interface with SiO2. The PC–DME mixture formed a well-ordered structure at the SiO2 interface, with the viscosity increasing from 0.5 mPa s in the bulk to 105 mPa s at 25 nm from the SiO2 surface. This long-range structure resulted from the preferential concentration of DME on the SiO2 surface owing to the different absorptivities of the solvent molecules. LiClO4 addition reduced the distance from the SiO2 surface at which the solution structure formed to 10 nm at 1.0 mol L–1 and 7.5 nm at 2.0 or 3.0 mol L–1. This interfacial structure affected ionic conduction and was consistent with the distance from the SiO2 surface at which the activation energy of ionic conduction in solid–liquid systems became 10 kJ mol–1 greater than the bulk value. The disproportionation of the solvent mixture at the SiO2 interface was competitive with ion solvation but was suppressed when the [DME]/[Li+] ratio was ≤2.6.

Measurement time Shortening of measurement timeWe have established a method for measuring the zeta potential generated at the interface between a nonaqueous electrolyte solution utilized in LiClO 4 /propylene carbonate (PC) electrolyte and lithium cobalt oxide (LiCoO 2 ) by the streaming potential method. Since the surface potential of the metal oxide dispersed in the aprotic nonaqueous solvent contains only a very small amount of water-based potential-determining ions such as H + and OH − , the potential is determined by the adsorption of the solvated electrolyte itself. Unlike aqueous systems with potential-determining ions that exhibit specific adsorption, it took a very long time until the equilibrium state of the ion distribution near the solid surface was reached and the potential stabilized, with a time constant that amounted to about 5 minutes. Therefore, a detailed analysis of the change over time of the potential after the pressure setting showed that the predictive potential showed a change over time with almost a single relaxation having certain time constant. The measurement time of the streaming potential was corresponded to about the time constant, and the resulting zeta potential showed an anomalous concentration dependence as a maximum around 1.0 mol L −1 PC and a minimum at 1.5 mol L −1 PC for the concentration of each solution.

This retrospective study of patients with breast cancer investigated the relationship between preoperative physical function and the postoperative length of stay (LOS). [Participants and Methods] Eightytwo patients with breast cancer who underwent a total mastectomy were divided into a normal LOS group (n=46, postoperative LOS ≤7 days) and a prolonged LOS group (n=36, postoperative LOS >7 days). Demographic data, clinical findings, and motor function were compared between the two groups. Motor function was assessed using tests that measured the risk of impaired mobility due to locomotive syndrome. [Results] Body height, resection of axillary lymph nodes, and the two-step score were significantly associated with a prolonged postoperative LOS. [Conclusion] The results of this study show that a decreased preoperative two-step score was significantly associated with a prolonged LOS. This finding indicates that this test might be useful for predicting longer LOS in patients with breast cancer.

A mixed solvent containing two or more solvents is used for the electrolyte of lithium-ion batteries for increasing the conductivity. It is well known that an increase of conductivity by addition of low viscose solvent such as DME solvent1). On the other hand, we focus the influence of the solid phase for the liquid properties; for example, the ionic conductivity of the 1 mol L-1 LiClO4 propylene carbonate (PC)- 1,2-dimethoxyethane (DME) solution was hindered by the existence of LiCoO2 powder.2) In previous studies of Boyer et al., the solution composition on the carbon surface varies from that of the original one of the binary EC-DMC solution due to the affinity of DMC to carbon surface depending on the surface potential by MD simulation.3) In these studies, the solid surface properties influence the structure of solvation and ionic interaction and so on within a few – 100 nanometers. However the influenced distance is still not clear and depends on the measured properties. In this study, the variation of ionic conductivity and its related properties of LiClO4 solution coexisting with SiO2 nanoparticles in binary solvents induced by disproportionation of solvent composition, since SiO2 is conventionally utilized for separator, solvophilic surface modification and so on, and obtained result might be useful. We used PC-DME solution in which LiClO4 was dissolved as liquid phase, and used SiO2 with a particle size of 12 nm as the solid phase. Both of them were mixed at a volume ratio of 15 to 70% to obtain a paste-like samples. By using the particle size of this size, the thickness of the liquid phase existing on the SiO2 surface was several nm to several tens nm, and the solution information at the SiO2 interface could be obtained. The thickness of the liquid phase was obtained by dividing the volume of the liquid phase by the surface area of the solid phase. We performed AC impedance measurement and quantitative 1HNMR measurement on this sample. Furthermore, resonance shear viscosity measurement (RSM) was performed to obtain the local viscosity of the electrolyte near the SiO2 surface. Dependence of the electric conductivity; σ on the molar fraction of DME in binary solvent for the SiO2/1 molL-1 LiClO4-PC1-x DME x coexisting system in several liquid content was shown in Fig 1. In the SiO2/1 mol L-1 LiClO4 PC-DME coexisting system, the composition ratio at which the electric conductivity has the maximum value shifted toward the lower DME content as the proportion of SiO2 increased. At the liquid content of 20 vol%, the electrical conductivity simply decreased with DME content. From the behavior of electric conductivity, it is suggested that the effect of lowering the viscosity of DME cannot be obtained in the solid-liquid coexisting system. From the results of 1H-qNMR measurement adding SiO2 to each solution, it became clear that the mobility of the solvent molecules, which exists near the SiO2 surface, decreased due to the interaction with the SiO2 surface. Liquid volume fraction dependences of the 1H-qNMR detection amount of SiO2/PC-DME sample showed that the detection amount of DME significantly decreased with the addition of SiO2, whereas the decrease of PC detection amount is suppressed. It is suggested that DME molecules preferentially interacted with silica surfaces and was concentrated to solid surface. From the results of the RSM, the local viscosity of the PC-DME solution increased from a distance farther from SiO2 surface than those of the PC and DME pure solutions. Since the exchange of solvent molecules existing on the SiO2 surface and the solvent molecules existing in the bulk was suppressed by the phase separation of the solution, a long-range DME layer having a high viscosity was formed on the SiO2 surface. However, in high concentration solutions, DME molecules formed a stable solvation structure with Li+ and are not concentrated on the SiO2 surface and do not cause disproportionation of the solution composition. Therefore, in the RSM measurement, the distance from the SiO2 surface where the local viscosity increases in the PC-DME solution decreased with increasing concentration. [Reference] Y. Matsuda et al., J. Electrochem. Soc., 128, 2552 (1981). Y. Suzuki et al., Electrochemistry, 87, 294 (2019). M. J. Boyer et al., Phys. Chem. Chem. Phys., 18 (2016) Figure 1