A Theoretical study on the charge and discharge states of Na-ion battery cathode material,Na1+xFePO4F

Na₂FePO₄F is a promising cathode material for a Na-ion battery because of its high electronic capacity and good cycle performance. In this work, first principle calculations combined with cluster expansion and the Monte Carlo method have been applied to analyze the charge and discharge processes of Na₂FePO₄F by examining the voltage curve and the phase diagram. As a result of the density functional theory calculation and experimental verification with structural analysis, we found that the most stable structure of Na_1.5FePO₄F has the P2₁/b11 space group, which has not been reported to date. The estimated voltage curve has two clear plateaus caused by the two-phase structure composed of P2₁/b11 Na_1.5FePO₄F and Pbcn Na₂FePO₄F or Na₁FePO₄F and separated along the c-axis direction. The phase diagram shows the stability of the phase-separated structure. Considering that Na₂FePO₄F has diffusion paths in the a- and c-axis directions, Na₂FePO₄F has both innerphase and interphase diffusion paths. We suggest that the stable two-phase structure and the diffusion paths to both the innerphase and interphases are a key for the very clear plateau. We challenge to simulate a nonequilibrium state at high rate discharge with high temperature by introducing a coordinate-dependent chemical potential. The simulation shows agreement with the experimental discharge curve on the disappearance of the two plateaus. © 2018 Wiley Periodicals, Inc.     

The structural evolution of alkoxy-derived gel during drying

The effects of drying temperature on the structural evolution of alkoxy-derived silica gel prepared using various catalysts have been investigated. The dependence of specific surface area, S_g, reflecting the structure, on the temperature of drying was remarkable for a non-catalyzed xerogel. The effect of drying temperature on the S_g of an ammonia-catalyzed xerogel was also found but was not very large. The S_g of xerogels obtained by drying at 60°C was always higher by 50% than the gels dried at 30°C without regard to the aging temperature. The S_g of xerogels from HCl-catalyzed solution was of the order of several m²/g, however, the S_g of the aerogel obtained by hypercritical drying of the wet gel from a similar solution was about 800 m²/g. These phenomena were understood on the basis of SAXS measurements on both wet gels and aerogels.     

Structural changes of poly-L-lysine in solution and lyophilized form

Two structural changes of poly-l-lysine have been studied by various spectroscopic techniques; one is a structural change of a random coil sample in solution to a mixture of alpha-helix and beta-sheet during rapid freezing in the lyophilizing process, and the other is a pressure-induced structural change from an alpha-helix to a beta-sheet structure for a lyophilized sample.     

Interlaboratory evaluation of two enzyme-linked immunosorbent assay kits for the determination of crustacean protein in processed foods

The labeling of foods containing material derived from crustaceans such as shrimp and crab is to become mandatory in Japan because of increases in the number of allergy patients. To ensure proper labeling, 2 novel sandwich enzyme-linked immunosorbent assay (ELISA) kits for the determination of crustacean protein in processed foods, the N kit (Nissui Pharmaceutical Co., Ltd, Ibaraki, Japan) and the M kit (Maruha Nichiro Holdings, Inc., Ibaraki, Japan), have been developed. Five types of model processed foods containing 10 and/or 11.9 microg/g crustacean soluble protein were prepared for interlaboratory evaluation of the performance of these kits. The N kit displayed a relatively high level of reproducibility relative standard deviation (interlaboratory precision; 4.0-8.4% RSDR) and sufficient recovery (65-86%) for all the model processed foods. The M kit displayed sufficient reproducibility (17.6-20.5% RSDR) and a reasonably high level of recovery (82-103%). The repeatability relative standard deviation (RSDr) values regarding the detection of crustacean proteins in the 5 model foods were mostly < 5.1% RSDr for the N kit and 9.9% RSDr for the M kit. In conclusion, the results of this interlaboratory evaluation suggest that both these ELISA kits would be very useful for detecting crustacean protein in processed foods.     

Synthetic Study of (−)‐Norzoanthamine: Construction of the ABC Ring Moiety

Throw your hat in the ring : A highly diastereoselective synthesis of the ABC rings of (?)‐norzoanthamine has been achieved starting from the (?)‐Hajos–Parrish ketone (see scheme). Three asymmetric quaternary carbon centers on the C ring were constructed by a 1,4‐addition, and an intramolecular Diels–Alder reaction provided a trans‐decalin scaffold on the AB rings.

     

Sonoporation-mediated transduction of siRNA ameliorated experimental arthritis using 3 MHz pulsed ultrasound

The goal of this feasibility study was to examine whether sonoporation assisted transduction of siRNA could be used to ameliorate arthritis locally. If successful, such approach could provide an alternative treatment for the patients that have or gradually develop adverse response to chemical drugs. Tumor necrosis factor alpha (TNF-α) produced by synovial fibroblasts has an important role in the pathology of rheumatoid arthritis, inducing inflammation and bone destruction. In this study, we injected a mixture of microbubbles and siRNA targeting TNF-α (siTNF) into the articular joints of rats, and transduced siTNF into synovial tissue by exposure to a collimated ultrasound beam, applied through a probe 6 mm in diameter with an input frequency of 3.0 MHz, an output intensity of 2.0 W/cm² (spatial average temporary peak; SATP), a pulse duty ratio of 50%, and a duration of 1 min. Sonoporation increased skin temperature from 26.8 °C to 27.3 °C, but there were no adverse effect such as burns. The mean level of TNF-α expression in siTNF-treated knee joints was 55% of those in controls. Delivery of siTNF into the knee joints every 3 days (i.e., 7, 10, 13, and 16 days after immunization) by in vivo sonoporation significantly reduced paw swelling on days 20–23 after immunization. Radiographic scores in the siTNF group were 56% of those in the CIA group and 61% of those in the siNeg group. Histological examination showed that the number of TNF-α positive cells was significantly lower in areas of pannus invasion into the ankle joints of siTNF- than of siNeg-treated rats. These results indicate that transduction of siTNF into articular synovium using sonoporation may be an effective local therapy for arthritis.     

Atomic structure of two-dimensional binary surface alloys: Si(111)-√21 × √21 superstructure

The atomic structures of Au and Ag co-adsorption-induced √21 × √21 superstructure on a Si(111) surface, i.e., (Si(111)-√21 × √21-(Au, Ag)), where the Si(111)-5 × 2-Au surface is used as a substrate, have been investigated using reflection high-energy positron diffraction (RHEPD) and photoemission spectroscopy. From core-level spectra, we determined the chemical environments of Ag and Au atoms present in the Si(111)-√21 × √21-(Au, Ag) surface. From the rocking curve and pattern analyses of RHEPD, we found that the atomic coordinates of the Au and Ag atoms were approximately the same as those of the Au and Ag atoms in other Si(111)-√21 × √21 surfaces with different stoichiometries. On the basis of the core-level and RHEPD results, we revealed the atomic structure of the Si(111)-√21 × √21-(Au, Ag) surface.     

Magnetooptical Property of Sodium Borosilicate Gel-Glass Containing Bi-YIG Fine Particles

Composite materials which consist of ferro- or ferrimagnetic fine particles in a glass matrix are expected to have a large residual magnetization and coercive force because of their fine magnetic domain structure, and has potential for superior magneto-optical properties compared with single or polycrystalline materials. In this study, the sodium borosilicate (NBS) glass containing Bi-substituted yttrium iron garnet (Bi _x Y_3–x Fe₅O₁₂: BiYIG) fine particles, which show a superior magneto-optical effect, was prepared by the sol-gel method. BiYIG fine particles were stable in NBS gel-glass matrix during densification because the sintering temperature (580°C) of NBS gel was low enough to avoid pyrolysis of BiYIG and the reaction between BiYIG fine particles and the matrix. The Faraday rotation angle spectrum of the composite after deducting the contribution of the NBS glass matrix was intermediate between the reported ones of YIG and Bi_0.25YIG polycrystalline thin films. The change of the Faraday rotation angles of the composite with imposing magnetic field showed a hysteresis loop. It was in good agreement with that of the magnetization curve of the composite.     

Magneto-Optical Properties of Silica Gel Containing Magnetite Fine Particles

The magnetic composite materials that consist of transparent matrix and magnetic fine particles are expected to have large residual magnetization and coercive force because of their fine magnetic domain structure, and also to show magneto-optical effects. Silica gels containing magnetite (Fe₃O₄) fine particles were prepared by sol-gel method. The magnetic, optical and magneto-optical properties of the composites were investigated by measurements of magnetization curves, UV-visible spectra and Faraday rotation in visible range. The saturation magnetization of the composite was almost as same as that expected from the amount of magnetite fine particles in it. Although the composites had large and broad absorption at around 400 nm, they still maintained their transparency. The origins of decrement of transparency attributed to the optical absorption of magnetite and scattering due to magnetite fine particles. The whole composites showed positive Faraday rotation under external static magnetic field due to the large contribution of diamagnetic silica gel matrix. Magnetite contributed negative Faraday rotation with maximum at around 470–480 nm to the magneto-optical spectra of the composites.