Biomedical subjects

Takao Itoh

Publications and source records attributed to Takao Itoh.

4 recordsLinked to original sources

PubMed2003

The lowest excited triplet (T1) energies of p-methoxybenzaldehyde and p-cyanobenzaldehyde vapors estimated from the temperature dependence of the T2(n, pi) phosphorescence and the S1(n, pi) fluorescence spectra.

Invisible energy levels of the T1(pi, pi*) state of p-methoxybenzaldehyde (anisaldehyde) and p-cyanobenzaldehyde vapors have been estimated through the temperature dependence of the T2(n, pi*) --> S0 phosphorescence and the S1(n, pi*) --> S0 delayed fluorescence spectra. It is shown that the T1(pi, pi*) levels are located at 900 +/- 100 and 300 +/- 100 cm(-1) below the T2(n, pi*) levels, respectively, for p-methoxybenzaldehyde and p-cyanobenzaldehyde vapors. The estimated T1 energy levels are in good agreement with the phosphorescence origins in rigid glass at 77 K.

Benzaldehydes↗

PubMed2002

Excited-state dynamical behavior of 1,4-anthraquinone in a fluid solution.

The excited triplet-state transient time profiles of 1,4-anthraquinone (1,4-AQ) have been measured in a degassed CCl4 fluid solution at different temperatures near room temperature, together with the steady-state emission spectra, which consist of the S1(n, pi*) and weak S2(pi, pi*) fluorescence at room temperature, and of the T1(pi, pi*) phosphorescence at 77 K. Quantitative analysis of the T1 triplet decay profiles measured as a function of temperature provides estimates for the energy and rates that characterize the excited-state dynamical behavior of 1,4-AQ.

Anthraquinones↗

PubMed2002

Toward understanding the different function of two types of parenchyma cells in bamboo culms.

The bamboo, woody monocot, has two types of parenchyma cells in the ground tissues of its culm, in contrast to a single type of parenchyma cell in rice, maize and other major crop species. The distribution of cell wall components, including lignin, (1-->3), (1-->4)-beta-D-glucans (MGs), the highly-substituted glucuronoarabinoxylans (hsGAXs) and low-branched xylans (lbXs) in ground parenchyma tissue of Phyllostachys heterocycla var. pubescens culms was studied at various developmental stages using light microscopy (LM), UV-microscopy, transmission electron microscopy (TEM) and immunolabeling techniques. The short parenchyma cell walls were lignified in 2-month-old bamboo culms just as the long parenchyma cell walls were. The lignified regions were confined to the portions in contact with the long parenchyma cell walls, while the walls at the cell corner region never lignified, even in 7-year-old culms. Significant differences were also found in the hemicellulose distribution between the short and long parenchyma cell walls. In bamboo parenchyma tissue, MGs were localized in short parenchyma cell walls and few were found in long parenchyma cell walls in both young and 7-year-old culms. The distribution of hsGAXs was similar to that of MGs in young culms, but they only appeared in the cell corner region of short parenchyma cells in old culms. Low-branched xylans were distributed in the lignified, but not in unlignified parenchyma cell walls. Based on this evidence, the differences of function in both short and long parenchyma cells in a bamboo culm are discussed.

Cell Wall↗

PubMedDate not supplied

X-ray microbeam and electron diffraction experiments on developing xylem cell walls.

This paper describes the first successful application of the novel technique of X-ray microbeam diffraction to the study of wood cell walls in developing xylem tissue. The method enabled us to obtain quantitative diffraction diagrams from single cell walls. It was further combined with selected area electron diffraction. We find that the crystal size of cellulose is increasing from the primary wall (P, <19 A) over the outer layer (S(1), 19 A) to the middle layer of the secondary wall (S(2), 24 A). In particular, the cellulose crystals formed in the primary wall consist of an extremely low-crystalline state of cellulose I. We suggest the more applicable concept of microfibrils with increasing lateral disorder, similar to cellulose IV(I).