Norio Tobori

Charge–discharge properties of a cathode prepared with ketjen black as the electro-conductive additive in lithium ion batteries

Abstract In order to investigate the influence of the dispersion state of electro-conductive additives on the properties of lithium ion batteries, we examined the charge–discharge properties of cathodes prepared with suspensions of ketjen black (KB) dispersed in an organic solvent with different particle sizes. Discharge capacity, durability and resistance to high-current discharge of the cathode prepared from a well-dispersed suspension was higher than those of the cathode prepared with ketjen black powder. Because ketjen black particles in the cathode prepared from a well-dispersed suspension formed a conductive dense-network uniformly, despite the low amount of additive, we concluded that an electro-conductive network made of ketjen black, which can transmit electrons smoothly from active materials to the collector, formed in the cathode when the cathode was prepared from a well-dispersed suspension.

Preparation of pH-sensitive Anionic Liposomes Designed for Drug Delivery System (DDS) Application

We prepared pH-sensitive anionic liposomes composed solely of anionic bilayer membrane components that were designed to promote efficient release of entrapped agents in response to acidic pH. The pH-sensitive anionic liposomes showed high dispersion stability at neutral pH, but the fluidity of the bilayer membrane was enhanced in an acidic environment. These liposomes were rather simple and were composed of dimyristoylphosphatidylcholine (DMPC), an anionic bilayer membrane component, and polyoxyethylene sorbitan monostearate (Tween 80). In particular, the present pH-sensitive anionic liposomes showed higher temporal stability than those of conventional DMPC/DPPC liposomes. We found that pHsensitive properties strongly depended on the molecular structure, pKa value, and amount of an incorporated anionic bilayer membrane component, such as sodium oleate (SO), dimyristoylphosphatidylserine (DMPS), or sodium β-sitosterol sulfate (SS). These results provide an opportunity to manipulate liposomal stability in a pH-dependent manner, which could lead to the formulation of a high performance drug delivery system (DDS).

Control of pore distribution of porous carbons derived from Mg2+ porous coordination polymers

We have developed porous carbons with various pore sizes from porous coordination polymers (PCPs) with Mg2+ and benzene carboxylate linkers. The pore sizes of the porous carbons were tuned systematically according to the dimensionality of inorganic building blocks and the metal–oxygen–metal connectivity of the PCP frameworks.

Synthesis of Oligodiacetylene Derivatives from Flexible Porous Coordination Frameworks

Oligodiacetylenes (ODAs) with alternating ene-yne conjugated structure are significant materials for optical and electronic properties. Due to the low solubility of ODAs in common solvents, the synthetic approaches are limited. Here we disclose a new synthetic approach of ODAs without a side alkyl chain using a porous coordination polymer (PCP) as a sacrificial template. 1,2-Bis(4-pyridyl)butadiyne, which works as a monomer, was embedded in the flexible framework of the PCP, and ODAs were synthesized via utilization of the anisotropic thermal expansion of the PCP crystal. The oligomeric state of ODAs depends on the metal ion and coligand of the precursor.

The nanostructure of murine alveolar bone and its changes due to type 2 diabetes

Alveolar bone - the bony ridge containing the tooth sockets - stands out by its remodeling activity where bone is being formed and resorbed at a much higher rate than in any other bony tissue. Teeth that are anchored in the jaw through the periodontal ligament exert very large localized loads during mastication that could lead to a unique adaptation of the collagen/mineral structure in the bone. Our aim was to characterize the nanostructure of alveolar bone and to determine the influence of diabetes on structural characteristics of the mineralized matrix. Using small- and wide-angle X-ray scattering (SAXS/WAXS), we studied a spontaneous diabetic mouse model (KK+) and its corresponding healthy controls (KK-) (n=6) to determine the size and mutual alignment of the mineral nanoparticles embedded in the collagen matrix. On cross-sections (buccal-lingual) of the first molar multiple line scans with a spatial resolution of 30μm were performed on each sample, from the lingual to the buccal side of the mandible. Mineral particle thickness and length are decreasing towards the tooth in both buccal and lingual sides of alveolar bone. While mineral particles are well aligned with the long axis of the tooth on the buccal side, they are in a quarter of the measurements oriented along two preferred directions on the lingual side. These nanostructural differences can be interpreted as the result of an asymmetric loading during mastication, leading to a tilting of the tooth in its socket. In diabetic mice particle thicknesses are smaller compared to control animals.

Membrane permeation of giant unilamellar vesicles and corneal epithelial cells with lipophilic vitamin nanoemulsions

Nanoemulsions of a lipophilic vitamin, retinol palmitate (vitamin A; VA), have a therapeutic effect on corneal damage. The nanoemulsion based on a triblock-type polymer surfactant with polyoxyethylene and polypropylene, EO100PO70EO100 (EOPO) showed superior efficacy, as compared with a nanoemulsion based on polyoxyethylene (60) hydrogenated castor oil (HCO). We studied the mechanism of VA nanoemulsions related to efficacy from the viewpoint of the interaction with plasma membrane-mimicking giant unilamellar vesicles (GUVs) and the plasma membrane permeation in corneal epithelial cells. When nanoemulsions and GUVs doped with fluorescent compounds were mixed each other, and observed by confocal laser microscopy, EOPO nanoemulsions induced endocytic morphological changes like strings and vesicles of the bilayer drawn inside a GUV by budding. Judging by isothermal titration calorimetry and ζ potential measurements, the EOPO nanoemulsions seemed to have stronger hydrophobic interactions with the lipid bilayer because of lower coverage of the core interface. Next, when the nanoemulsions prepared with a pyrene derivative of retinol (VApyr) were applied to corneal epithelial cells, the EOPO nanoemulsions greatly permeated the cells and gathered around the cell nucleus, as compared with HCO nanoemulsions. Furthermore, according to the three-dimensional images of the cell, it was found that the vesicles that absorbed nanoemulsions formed from the plasma membrane as real endocytosis, and were transported to the area around the nucleus. Consequently, it is likely that EOPO nanoemulsions entered the cell by membrane-mediated transport, delivering VA to the cell nucleus effectively and enhancing the effects of VA.

Characterization of oil-producing yeast Lipomyces starkeyi on glycerol carbon source based on metabolomics and 13C-labeling

Lipomyces starkeyi is an oil-producing yeast that can produce triacylglycerol (TAG) from glycerol as a carbon source. The TAG was mainly produced after nitrogen depletion alongside reduced cell proliferation. To obtain clues for enhancing the TAG production, cell metabolism during the TAG-producing phase was characterized by metabolomics with 13C labeling. The turnover analysis showed that the time constants of intermediates from glycerol to pyruvate (Pyr) were large, whereas those of tricarboxylic acid (TCA) cycle intermediates were much smaller than that of Pyr. Surprisingly, the time constants of intermediates in gluconeogenesis and the pentose phosphate (PP) pathway were large, suggesting that a large amount of the uptaken glycerol was metabolized via the PP pathway. To synthesize fatty acids that make up TAG from acetyl-CoA (AcCoA), 14 molecules of nicotinamide adenine dinucleotide phosphate (NADPH) per C16 fatty acid molecule are required. Because the oxidative PP pathway generates NADPH, this pathway would contribute to supply NADPH for fatty acid synthesis. To confirm that the oxidative PP pathway can supply the NADPH required for TAG production, flux analysis was conducted based on the measured specific rates and mass balances. Flux analysis revealed that the NADPH necessary for TAG production was supplied by metabolizing 48.2% of the uptaken glycerol through gluconeogenesis and the PP pathway. This result was consistent with the result of the 13C-labeling experiment. Furthermore, comparison of the actual flux distribution with the ideal flux distribution for TAG production suggested that it is necessary to flow more dihydroxyacetonephosphate (DHAP) through gluconeogenesis to improve TAG yield.