Study of nanoscale structural changes in isolated bamboo constituents using multiscale instrumental analyses

To reveal morphological changes in bamboo constituents induced by delignification and hemicelluloses removal processes, changes in chemical composition and dynamics were examined at molecular‐ to nano‐scales, using scanning electron microscopy images, attenuated total reflection infrared spectra, solid state nuclear magnetic resonance spectra, and relaxation time analysis at multiple hierarchical levels. Boiling removed spherical particles from the parenchymal cells of bamboo, leaving the cells containing water that had infiltrated into the nanostructure composed of carbohydrates and lignin. Treatment of the boiled bamboo with NaClO₂ solution removed most of lignin, leaving hemicellulose chains that made the parenchymal cells stretch. In contrast, treatment of the boiled bamboo with NaOH solution removed both hemicellulose and lignin, with the result that parenchymal cells shrank in the cross‐section direction. Furthermore, treatment of the delignified bamboo with NaOH solution demolished the parenchymal cells due to complete removal of hemicellulose and lignin. A nanostructural model proposed on the basis of molecular‐ to nano‐scale analyses was consistent with the changes of vascular bundles and parenchymal cells. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40243.     

Methane production by Methanothermobacter thermautotrophicus to recover energy from carbon dioxide sequestered in geological reservoirs

To recover energy from carbon dioxide sequestered in geological reservoirs, the geochemical effects of acidic and substrate- and nutrient-limiting conditions on methane production by the hydrogenotrophic methanogen Methanothermobacter thermautotrophicus were investigated in a simulated deep saline aquifer environment using formation water media retrieved from petroleum reservoirs.     

PLLA–collagen and PLLA–gelatin hybrid scaffolds with funnel-like porous structure for skin tissue engineering

In skin tissue engineering, a three-dimensional porous scaffold is necessary to support cell adhesion and proliferation and to guide cells moving into the repair area in the wound healing process. Structurally, the porous scaffold should have an open and interconnected porous architecture to facilitate homogenous cell distribution. Moreover, the scaffolds should be mechanically strong to protect deformation during the formation of new skin. In this study, the hybrid scaffolds were prepared by forming funnel-like collagen or gelatin sponge on a woven poly(l-lactic acid) (PLLA) mesh. The hybrid scaffolds combined the advantages of both collagen or gelatin (good cell-interactions) and PLLA mesh (high mechanical strength). The hybrid scaffolds were used to culture dermal fibroblasts for dermal tissue engineering. The funnel-like porous structure promoted homogeneous cell distribution and extracellular matrix production. The PLLA mesh reinforced the scaffold to avoid deformation. Subcutaneous implantation showed that the PLLA–collagen and PLLA–gelatin scaffolds promoted the regeneration of dermal tissue and epidermis and reduced contraction during the formation of new tissue. These results indicate that funnel-like hybrid scaffolds can be used for skin tissue regeneration.     

Biodesulfurization of alkylated forms of dibenzothiophene and benzothiophene by Sphingomonas subarctica T7b

Sphingomonas subarctica T7b was isolated from soil in Toyotomi, Hokkaido, Japan as an organism capable of desulfurizing aromatic hydrocarbons in light gas oil (LGO) through enrichment culture. S. subarctica T7b could grow on mineral salt sulfur-free (MSSF) medium with the n-tetradecane oil phase containing dibenzothiophene (DBT), alkyl dibenzothiophenes (alkyl DBTs) or alkyl benzothiophenes (alkyl BTs) as the sole sulfur source and desulfurize these compounds, but could not utilize the tetradecane as a carbon source. This is the first report of a gram-negative bacterium which can desulfurize 4,6-dibutyl DBT and 4,6-dipentyl DBT. The desulfurized product of DBT produced by this strain was 2-hydroxybiphenyl, as in the case of other DBT-desulfurizing bacteria. S. subarctica T7b could desulfurize LGO and the sulfur content was decreased to 41% within 36 h.     

Effects of long-term ingestion of difructose anhydride III (DFA III) on intestinal bacteria and bile acid metabolism in humans

Changes in the intestinal microbiota of 10 human subjects with long-term ingestion of 3 g/d difructose anhydride III (DFA III; 4 persons, 2 months; 3 persons, 6 months; and 3 persons, 12 months) were examined by denaturing gradient gel electrophoresis (DGGE). According to the answers to questionnaires, the subjects were divided into two groups (constipated and normal). The DGGE profile was different for every individual and each subject had unique profiles of intestinal microbiota. In the DGGE profiles of constipated subjects, the intensities of bands related to Bacteroides spp. increased. Moreover, the DFA III-assimilating bacteria, Ruminococcus sp. were isolated from subjects who ingested DFA III for 12 months. These strains showed 95% similarity of their 16S rDNA sequences with that of Ruminococcus obeum ATCC 29174(T) (X85101) and produced large amounts of acetic acid. DFA III ingestion for 2 months tended to increase total organic acids in feces, and tended to decrease fecal pH and the secondary bile acid (SBA) ratio in total bile acids. The SBA ratio in total bile acids corresponded to fecal pH. The production of SBA was decreased by low pH in vitro. These results indicated that DFA III ingestion in humans tended to lower intestinal pH, inhibited bile acid 7alpha-dehydroxylation activities and also tended to decrease the SBA ratios in total bile acids. Moreover, as another cause for the decrease in the SBA ratio in total bile acids, it was suggested that the number of bile acid 7alpha-dehydroxylating bacteria were decreased by DFA III ingestion.     

Release profiles of theophylline from microspheres consisting of dextran derivatives and cellulose acetate butyrate: effect of polyion complex formation

The objective of this study was to evaluate the utility of mixtures among oppositely charged dextran derivatives as constituents of a controlled release microsphere. Carboxymethyldextran (CMD) and dextran sulfate (DS) were used as polyanions, and [2-(diethylamino) ethyl] dextran (EA) and [2-hydroxypropyltrimethylammonium] dextran (CDC) as polycations. The microspheres consisting of hydrophilic and hydrophobic polymers were prepared by emulsion-solvent evaporation method. The mixtures, CMD/EA, CMD/CDC, DS/EA, and DS/CDC, were used as hydrophilic polymers, because they can interact with each other to form polyion complexes for the improvement of sustained-release performances. Cellulose acetate butyrate and theophylline were used as a model hydrophobic polymer and a model drug, respectively. The yield of microspheres was excellent (more than 95%). According to observation, by scanning election microscopy (SEM) microspheres were spherical with a rough surface. The in vitro drug release from microspheres was examined in the JP XIV first fluid, pH 1.2, and second fluid, pH 6.8, at 37°C, and 100 rpm. In the DS/CDC system, drug release was depressed by formation of a polyion complex and not affected by pH of dissolution medium. The release rate was modulated by the ratio of hydrophilic and hydrophobic matrix. This particulate system, in which the polyion complex matrix is strengthened by a hydrophobic polymer, is a promising formulation for drug delivery.     

Experimental and theoretical investigations on morphological changes of γ′ precipitates in Ni -Al single crystals during uniaxial stress-annealing

Influences of the external tension and compression on the morphological changes of precipitates during coarsening in an Ni-15 at. % Al single crystal were experimentally investigated, and theoretical evalutions on the energetically favourable shape and its orientation were also derived based upon the anisotropic elasticity theory. The shape transformation with growth in size is experimentally found to follow the sequence: cuboidrod plate, under all annealing conditions, i.e. compression-annealing, tension-annealing and external stress-free annealing. However, the external stresses give preferential orientation to such microstructures. The tension of the [001] direction aligns the rods and plates along the tension axis, while the compression aligns them on a plane perpendicular to the compression axis. Theoretical evaluations based upon the anisotropic elasticity for the energetically favourable shapes and orientations of are consistent with experimental results except in the appearance of rods after compression-annealing. This discrepancy is understood by a conception that the shape transformation is influenced not only by energetics in the elastic strain and interfacial energies, but also by elastic interaction energy.Formerly at the Graduate School of Nagoya Institute of Technology.