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Surface-fixation induced emission is a fluorescence enhancement phenomenon, which is expressed when dye molecules satisfy a specific adsorption condition on the anionic clay surface. The photophysical behaviors of two types of cationic acridinium derivatives [10-methylacridinium perchlorate (Acr+) and 10-methyl-9-phenylacridinium perchlorate (PhAcr+)] on the synthetic saponites with different anionic charge densities were investigated. Under the suitable conditions, the fluorescence quantum yield (Φf) of PhAcr+ was enhanced 22.3 times by the complex formation with saponite compared to that in water without saponite. As the inter-negative charge distance of saponite increased from 1.04 to 1.54 nm, the Φf of PhAcr+ increased 1.25 times. In addition, the increase in the negative charge distance caused the increase in the integral value of the extinction coefficient and the radiative deactivation rate constant (kf) and the decrease in the nonradiative deactivation rate constant. It should be noted that the 2.3 times increase in kf is the highest among the reported values for the effect of clay. From these results, it was concluded that the photophysical properties of dyes can be modulated by changing the charge density of clay minerals.

The adsorption behavior of cationic organic molecules was examined on a clay surface. Systematically chosen pyridinium salts and artificially synthesized anionic clay were used. The adsorption equi...

In this study, the adsorption behavior of mono-cationic acridinium derivatives on a synthetic clay mineral (Sumecton SA) was investigated. The acridinium derivatives were adsorbed on the clay surface without aggregation, as found from the changes in the absorption spectra of the acridinium derivatives with SSA and without SSA represented by two-component equilibrium systems of adsorbed and non-adsorbed components. Following the Langmuir isotherm analysis, the adsorption equilibrium constants and maximum adsorption amounts were determined for acridinium derivatives, and the Gibbs free energy change (ΔG) was calculated to be in the range of −33.8 to 40.0 kJ mol−1 from the adsorption equilibrium constants. These results indicated that the adsorption of acridinium derivatives on the clay surface was an exergonic reaction. Moreover, thermodynamic parameters such as enthalpy change (ΔH) and entropy change (ΔS) were obtained from the temperature effect experiments. For all acridinium derivatives, ΔH (from −7.82 to −26.0 kJ mol−1) and ΔS (0.047–0.088 kJ mol−1 K−1) were found to be negative and positive, respectively. It was suggested that not only electrostatic interactions, but also van der Waals forces and hydrophobic interactions played an important role in the adsorption of cationic aromatic molecules on the clay surface. Because these thermodynamic parameters showed a strong correlation with the molecular cross-sectional area of acridinium derivatives, it was suggested that the contribution of hydrophobic interactions became smaller as the molecular cross-sectional area became larger.

The mechanism of the cycloreversion reaction of a fulgide derivative in the higher excited states (Sn states) pumped by the stepwise two-photon excitation was investigated by femtosecond transient absorption spectroscopy. The first photon excitation of the ground state by the visible light led to the production of the Franck–Condon 1B state, which underwent internal conversion to the 2A state with 100 fs time constant and the structural reorganization accompanied with the vibrational cooling with 1.5 ps time constant. After these relaxation processes, the 2A state underwent the cycloreversion reaction (11% reaction yield) with competitive nonradiative as well as radiative deactivation processes into the ground state with a time constant of 10 ps. Under the double-pulse pump condition, whereas the excitation of the 1B state induced no remarkable cycloreversion reaction, the excitation of the 2A state resulted in the marked enhancement of the cycloreversion reaction with a reaction quantum yield of ca. 80% ...

The thermal coefficient α (= dV/dT) of the redox potential (V) is an important physical parameter for thermal energy harvesting. We systematically investigated α of six Prussian blue analogues (M-P...

Prussian blue analogues (PBAs) are nanoporous materials that consist of a cyano-bridged three-dimensional (3D) metal framework, i.e., –M–NC–Fe–CN–M– (M = Cr, Mn, Fe, Co, Ni, Cu, and Cd), and a gues...

Background Glucose is used as an energy source in many organs and obtained from dietary carbohydrates. However, when the external energy supply is interrupted, e.g., during fasting, carbohydrates preserved in the liver and glycogenic precursors derived from other organs are used to maintain blood glucose levels. Glycerol and glycogenic amino acids derived from adipocytes and skeletal muscles are utilized as glycogenic precursors. Glycerol-3-phosphate dehydrogenase 1 (GPD1), an NAD +/NADH-dependent enzyme present in the cytosol, catalyzes the reversible conversion of glycerol-3-phosphate (G3P) to dihydroxyacetone phosphate (DHAP). Since G3P is one of the substrates utilized for gluconeogenesis in the liver, the conversion of G3P to DHAP by GPD1 is essential for maintaining blood glucose levels during fasting. We focused on GPD1 and examined its roles in gluconeogenesis during fasting. Methods Using GPD1 null model BALB/cHeA mice (HeA mice), we measured gluconeogenesis from glycerol and the change of blood glucose levels under fasting conditions. We also measured gene expression related to gluconeogenesis in the liver and protein metabolism in skeletal muscle. BALB/cBy mice (By mice) were used as a control. Results The blood glucose levels in the HeA mice were lower than that in the By mice after glycerol administration. Although lack of GPD1 inhibited gluconeogenesis from glycerol, blood glucose levels in the HeA mice after 1–4 h of fasting were significantly higher than that in the By mice. Muscle protein synthesis in HeA mice was significantly lower than that in the By mice. Moreover, blood alanine levels and usage of alanine for gluconeogenesis in the liver were significantly higher in the HeA mice than that in the By mice. Conclusions Although these data indicate that a lack of GPD1 inhibits gluconeogenesis from glycerol, chronic GPD1 deficiency may induce an adaptation that enhances gluconeogenesis from glycogenic amino acids.

Several symbiotic mutants of legume plants defective in nodulation have also been shown to be mutants related to arbuscular mycorrhizal (AM) symbiosis. The origin of the AM symbiosis can be traced back to the early land plants. It has therefore been postulated that the older system of AM symbiosis was partially incorporated into the newer system of legume-rhizobium symbiosis. To unravel the genetic basis of the establishment of AM symbiosis, we screened about 34,000 plants derived from ethyl methanesulfonate (EMS)-mutagenized Lotus japonicus seeds by microscopic observation. As a result, three lines (ME778, ME966 and ME2329) were isolated as AM-specific mutants that exhibit clear AM-defective phenotypes but form normal effective root nodules with rhizobial infection. In the ME2329 mutant, AM fungi spread their hyphae into the intercellular space of the cortex and formed trunk hyphae in the cortical cells, but the development of fine branches in the arbuscules was arrested. The ME2329 mutant carried a nonsense mutation in the STR-homolog gene, implying that the line may be an str mutant in L. japonicus. On the ME778 and ME966 mutant roots, the entry of AM fungal hyphae was blocked between two adjacent epidermal cells. Occasionally, hyphal colonization accompanied by arbuscules was observed in the two mutants. The genes responsible for the ME778 and ME966 mutants were independently located on chromosome 2. These results suggest that the ME778 and ME966 lines are symbiotic mutants involved in the early stage of AM formation in L. japonicus., Article, PLANT AND CELL PHYSIOLOGY. 55(5):928-941 (2014)

We examined the deposition of gold clusters through the reduction of a gold precursor sensitized by nonaggregated, assembled porphyrin molecules on an inorganic layered material surface in order to develop a novel strategy for constructing assemblies of gold clusters. Visible light irradiation on nonaggregated, assembled porphyrin on the inorganic surface in the presence of the gold precursor and an electron donor induced the deposition of gold NPs on the surface of the inorganic layered material. Uniform gold clusters, with an average diameter of 1.5 nm, were deposited on the surface without aggregation. The average interparticle distance between adjacent gold clusters (center to center) was 2.3 nm, which agrees well with the average intermolecular distance of the nonaggregated, assembled porphyrin molecules on the inorganic surface. Thus, the generated gold clusters appear to reflect the nonaggregated, assembled structure of the porphyrin molecules on the inorganic surface. This method, termed the photosensitized template reduction (PTR) method, is a useful and novel technique for the deposition of metal nanoparticles on the surfaces of supporting materials.

The molecular weight dependence of lamellar domain spacing of poly(2-vinylpyridine-g-styrene) was measured by small angle X-ray scattering (SAXS). The samples used are six three-arm star-shaped polymers having one polystyrene arm connected at the centre of a poly(2-vinylpyridine) chain. The volume fractions of grafted polystyrene chains, ƒ s , of the samples range from 0.45 to 0.78, though all the samples were confirmed to have alternating lamellar structure by SAXS and transmission electron microscopy. It was found that the relationship between lamellar domain spading, D, and the molecular weight, M, of the graft copolymers is given by D = 0.0153 M0.69 (nm) over the molecular weight range from 49 to 283 k irrespective of the difference in composition. The exponent 0.69 is quite close to 2 3 , which is predicted for AB diblock copolymers by several different theories. However, the magnitude of the prefactor in the above relationship is apparently smaller than that for styrene-2-vinylpyridine diblock copolymers. This difference can be explained by considering the difference in structure between AB diblock copolymers and ABB graft copolymers.

Poly(2-vinylpyridine-g-styrene)s were prepared by successive coupling reactions of polystyryl anion and poly-2-vinylpyridinyl anion prepared by anionic polymerizations, with trifunctional coupling agent, tris-bromomethylbenzene. Five samples were prepared and characterized. Their volume fractions of polystyrene graft,os, were determined to be 0.24, 0.34, 0.45, 0.58 and 0.67, respectively. Morphologies of the solvent-cast films of the samples were observed by transmission electron microscopy and small-angle X-ray scattering. It was revealed that two samples, with os of 0.24 and 0.34, show cylindrical structures, while the other three samples have alternating lamellar structures.