Thermal characteristics of nongraphitizable carbon negative electrodes with electrolyte in Li-ion batteries

Two kinds of nongraphitizable carbon were applied as active materials of negative electrodes in Li-ion batteries. The thermal properties of cycled electrodes mixed with or without commercial 1 M LiPF₆/EC–DMC electrolyte were investigated by TG–DSC from room temperature to 400 °C at a heating rate of 5 °C/min. Both kinds of lithiated electrodes showed exothermic peaks at about 310 °C due to decomposition of SEI by lithiated carbon powder. For the mixture of delithiated electrodes and electrolytes, the heat generation was attributed mainly to thermal decomposition of the electrolyte at about 280 °C. But for the mixture of lithiated electrodes and electrolytes, thermal risk mainly came from the reaction between original/secondary SEI and intercalated Li ions, which caused drastic heat generation at about 285 °C. Moreover, the thermal behavior of the mixture of cycled electrodes and electrolytes was directly related to the ratio between electrodes and coexisting electrolytes. When the ratio between electrodes and electrolytes was suitable, an endothermic reaction between SEI and electrolytes became dominant and depressed other exothermic heat, which reduced the thermal risk of the mixture of electrodes and electrolytes at elevated temperature.     

Setting properties of alginate impression materials in dynamic viscoelasticity

The viscoelastic properties of three alginate impression materials were investigated. A landmark of working time was calculated using a raw phase-time curve. A landmark of setting time was calculated from an inflection point of the divided difference of the first order in the share modulus-time curve. As a result, the working time was common at the point of delta = 45 degrees in variable frequencies. The mean value was obtained with less deviation. The setting times obtained were similar for variable frequencies. The mean values showed a distinct difference for each impression material.     

1 beta-Methyl-2-(5-substituted pyrrolidin-3-ylthio)carbapenems. 3. Synthesis and antibacterial activity of BO-2727 and its related compounds

The synthesis and biological activity of (1R,5S,6S)-2-[(3S,5S)- 5-substituted pyrrolidin-3-ylthio]- 6-[(R)-1-hydroxyethyl]-1-methyl-1-carbapen-2-em-3-carboxylic acid in which hydroxy-substituted aminoethyl, aminopropyl, and aminobutyl groups were introduced as substituents, are described. These derivatives showed potent antibacterial activity against Gram-positive and Gram-negative bacteria including P. aeruginosa. Among them, lenapenem (BO-2727, 7b), carrying an (R)-1-hydroxy-3-(N-methylamino)propyl group, was selected as a development candidate.     

LiPF6/methyl difluoroacetate electrolyte with vinylene carbonate additive for Li-ion batteries

A methyl difluoroacetate (MFA)-based LiPF₆ solution was applied as an electrolyte to improve the thermal stability of Li-ion batteries. The addition of vinylene carbonate (VC) improved the electrochemical characteristics of the electrolyte significantly, and satisfactory reversible capacity and cycling performance were obtained with a graphite negative electrode. The thermal stability of the electrolytes was investigated with DSC. Regardless of whether or not VC was used, the electrolyte exothermically decomposed at a temperature higher than 450 °C. The thermal behavior of a mixture of lithiated graphite and VC-added electrolyte was also studied in detail. The ratio between the electrolyte and the electrode was a dominant factor in the heat generation of the mixture. A sharp exothermic peak at about 330 °C was observed when the electrode was superabundant, but the heat value was much smaller than that obtained with 1 mol dm⁻³ LiPF₆/EC-DMC electrolyte under the same conditions. When the electrolyte was superabundant, a mild exothermic decomposition of the electrolyte became the dominant reaction in the mixture. X-ray photoelectron spectroscopic analysis was carried out on delithiated graphite electrodes to study the effect of VC additive on solid electrolyte interphase (SEI) modification. VC-added MFA-based electrolyte was considered to be a good candidate for developing safer Li-ion batteries.     

Crystallization and precipitation structures of quasicrystalline phase in rapidly solidified Al-Mn-X ternary alloys

Tranmission electron microscopic observations were carried out to reveal the solidification and precipitation structures of rapidly solidified Al-Mn-X alloys (X=Si or Zr), with particular focus on the formation of the icosahedral quasicrystals. On increasing the manganese content, the distribution of the icosahedral quasicrystals in the rapidly solidified alloys changed from the type of cell-boundary segregation to that of one component in the eutectic and the primarily dendritic phase. The precipitation of the icosahedral quasicrystals from the supersaturated solid solutions of the present alloys was restricted in the surface layers and/or largeangle grain boundaries. The orientation relationships between the icosahedral quasicrystals and the aluminium matrix were such that three mutually perpendicular two-fold axes of the icosahedron lie along the [100], , and [011] axes of the fcc crystallographic directions. The 15-fold symmetry diffraction pattern frequently obtained from (111) and/or (233) matrix planes could be explained by considering axial rotation between the five-fold and three-fold symmetry axes of the icosahedron and cubic lattices. It was suggested that the hierarchy of the free energies of the icosahedral phase and the other crystalline phases was very close.     

A case of xanthogranuloma of the urinary bladder following herniorrhaphy]

We report a case of xanthogranuloma of the bladder following herniorrhaphy. The patient complained of urinary frequency, residual feeling, and presented with a solid mass located on the dome of the bladder. He had undergone previous inguinal herniorrhaphy. Transurethral biopsy revealed an inflammatory change. Partial cystectomy was carried out for en bloc removal of the tumor. The histological diagnosis was xanthogranuloma of the bladder. Postoperatively, the symptoms disappeared. This is the sixth case report of xanthogranuloma of the urinary bladder and the first case following herniorrhaphy in the Japanese literature.