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Kono H.,Tomakomai National College of Technology
Carbohydrate Polymers | Year: 2014

Novel hydrogels were prepared from carboxymethyl cellulose (CMC) sodium salt by crosslinking with polyethylene glycol diglycidyl ether (PEGDE). The detailed structures of the hydrogels were determined via FTIR and solid-state NMR spectroscopic analyses. Increasing the feed ratio of PEGDE to CMC in the reaction mixture led to an increase in the crosslinking degree, which enhanced the physical strength of the hydrogels. The hydrogels exhibited enzyme degradability, and after 3 days of incubation with cellulase, 62-28 wt% of the CMC in the hydrogel was degraded under the conditions employed in this study. In addition, the hydrogels exhibited protein adsorption and release abilities, and the amounts of proteins adsorbed on the hydrogels and the release profile of the proteins depended on the protein sizes and crosslinking degree of the hydrogels. These unique properties might enable the use of CMC-based hydrogels as drug delivery system carriers for protein-based drugs if the biological safety of the hydrogel can be verified. © 2014 Elsevier Ltd. Source


Kono H.,Tomakomai National College of Technology
Carbohydrate Research | Year: 2013

1H and 13C chemical shift assignment of the anhydroglucose units (AGUs) that comprise cellulose acetate with the total degree of substitution of 2.33 was performed by a combination of two-dimensional NMR spectra obtained from COSY, TOCSY, HSQC-TOCSY, and HSQC experiments. In the TOCSY spectra, there are 13 kinds of correlation networks for the H1 to H6′ atoms of AGU; each 1H resonance of the 13 AGUs was assigned from the changes in the intensities of the 1H resonances with TOCSY spin-lock time during the TOCSY experiments. The ring 13C resonances were assigned via analysis of HSQC spectra. Comparison of the shift data enabled the assignment of the 13 AGUs as three types of 2,3,6-tri-acetylated, one type of 2-mono-, 3-mono-, 6-mono-, 2,3-di-, 2,6-di-, and 3,6-di-acetylated AGU, and unsubstituted AGU, and three types of AGUs located in end units. These shift data will be useful for characterizing the molecular structures of cellulose derivatives as well as cellulose acetate (CA). © 2013 Elsevier Inc. All rights reserved. Source


Kono H.,Tomakomai National College of Technology
Carbohydrate Polymers | Year: 2013

1H and 13C chemical shift assignment of the anhydroglucose units (AGUs) that comprise sodium carboxymethyl cellulose (CMC) with a degree of substitution (DS) of 0.70 was performed using 2D NMR spectra obtained from COSY, TOCSY, HSQC, and HSQC-TOCSY experiments. In the 2D COSY and TOCSY spectra, there are eight correlation networks for the H1 to H6- atoms of AGU; each 1H resonance of the eight AGUs was assigned from the changes in the intensities of the resonances with mixing times during the TOCSY experiments. The ring 13C resonances were assigned via analysis of HSQC-TOCSY spectra and confirmed via the HSQC spectra. Comparison of the shift data enabled the assignment of the eight AGUs as two types of both 2,3,6-tri-O- and 3,6-di-O-carboxymethylated, one type each of 2,6-di-O-, 2-mono- O-, and 6-mono-O-carboxymethylated AGU, and unsubstituted AGU. The obtained shift data will also be useful for characterization of the substitution distribution of other cellulose derivatives. © 2013 Elsevier Ltd. All rights reserved. Source


Nihashi S.,Tomakomai National College of Technology | Ohshima K.I.,Hokkaido University | Kimura N.,University of Tokyo
Journal of Climate | Year: 2012

Sea ice formation, its transport, and its melting cause the redistribution of heat and salt, which plays an important role in the climate and biogeochemical systems. In the Sea of Okhotsk, a heat and salt flux dataset is created in which such sea ice processes are included, with a spatial resolution of;12.5 km. The dataset is based on a heat budget analysis using ice concentration, thickness, and drift speed from satellite observations and the ECMWFInterimRe-Analysis (ERA-Interim) data. The salt flux calculation considers both salt supplied to the ocean from sea ice production and freshwater supplied when the icemelts. This dataset will be useful for the validation and boundary conditions of modeling studies. The spatial distribution of the annual fluxes shows a distinct contrast between north and south: significant ocean cooling with salt supply is shown in the northern coastal polynya region, while ocean heating with freshwater supply is shown in the south. This contrast suggests a transport of freshwater and negative heat by ice advection. The annual fluxes also show ocean cooling with freshwater supply in the Kashevarov Bank (KB) region and the central and eastern Sea ofOkhotsk, suggesting the effect of warm water advection. In the ice melt season, relatively prominent ice melting is shown in the coastal polynya region, probably due to large solar heating of the upper ocean. This indicates that the polynya works as a "meltwater factory" in spring, contrasting with its role as an "ice factory" in winter. In the coastal polynya region, the spatial distribution of phytoplankton bloom roughly corresponds with the ice melt region. © 2012 American Meteorological Society. Source


Kono H.,Tomakomai National College of Technology | Zakimi M.,Tomakomai National College of Technology
Journal of Applied Polymer Science | Year: 2013

Superabsorbent hydrogels were prepared from chitin dissolved in lithium chloride and N-methyl-2-pyrrolidinone by esterification crosslinking with 1,2,3,4-butanetetracarboxylic dianhydride (BTCA). The absorbency of the chitin hydrogel was strongly dependent on the ratio of BTCA feed to chitin. The hydrogel prepared at the feed ratio of 5 showed the highest absorbency (345 g/g-polymer), and the hydrogel was composed of 0.65 molecules of BTCA per monomer unit of chitin. The hydrogels exhibited good biodegradability by chitinase with a maximum degradation of 91% within 7 days. This method for obtaining the chitin hydrogel was also applicable to cellulose and chitin mixtures, and 1: 1 cellulose/chitin hybrid hydrogels could be obtained by the esterification crosslinking of a mixture with a 1: 1 molar ratio of cellulose and chitin. The optimal BTCA feed ratio of 5 resulted in the cellulose/chitin hydrogel with the highest water absorbency (329 g/g-polymer), and the hydrogel contained 0.65 molecules of BTCA per polysaccharide monomer unit. In addition, the hybrid hydrogels were degraded by cellulase as well as chitinase. © 2012 Wiley Periodicals, Inc. Source

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