MEASUREMENT OF DENITRIFICATION ACTIVITY OF THE BOTTOM SEDIMENT AT NOGAWA RIVER (Natural purification of an urban river ecosystem)

Nitrogen removal by denitrification in sediment and artificial substrate was measured at Nogawa River by continuous method, based on acetylene inhibition technique, during one year from December 1987 to November 1988. The quality of artificial substrate is an important factor for denitrification rate in a river bed sample. The denitrification rate per unit area in the river bed composed of concrete (13.8gN m⁻² year⁻¹) was higher than that in the gravel and sand (7.4gN m⁻² year⁻¹ ) river bed. The proportion of denitrificated nitrogen to the input nitrogen in the river was calculated. The average value for the concrete river bed was 0.3%, and 7.4% in the river bed of gravel and sand. From these results, if all area of Nogawa River was changed to a concrete bed, the proportion of denitrificatied nitrogen to input nitrogen is estimeted to be 1.7%, and about 3.1% in the case of a gravel and sand. Denitrification activity in the river bed of a small urban river was found to be dependent on the type of river bed.Article信州大学理学部付属諏訪臨湖実験所報告 7: 47-53(1991)departmental bulletin pape

Synthesis of Fluorescent Gelators and Direct Observation of Gelation with a Fluorescence Microscope

Fluorescein-, benzothiazole-, quinoline-, stilbene-, and carbazole-containing fluorescent gelators have been synthesized by connecting gelation-driving segments, including l-isoleucine, l-valine, l-phenylalanine, l-leucine residue, cyclo(l-asparaginyl-l-phenylalanyl), and trans-(1R,2R)-diaminocyclohexane. The emission behaviors of the gelators were investigated, and their gelation abilities studied against 15 solvents. The minimum gel concentration, variable-temperature spectroscopy, transmission electron microscopy, scanning electron microscopy, fluorescence microscopy (FM), and confocal laser scanning microscopy (CLSM) were used to characterize gelation. The intermolecular hydrogen bonding between the N-H and C=O of amide, van der Waals interactions and pi-pi stacking play important roles in gelation. The colors of emission are related to the fluorescence structures of gelators. Fibrous aggregates characterized by the color of their emission were observed by FM. 3D images are produced by the superposition of images captured by CLSM every 0.1 mu m to a settled depth. The 3D images show that the large micrometer-sized aggregates spread out three dimensionally. FM observations of mixed gelators are studied. In the case of gelation, two structurally related gelators with the same gelation-driving segment lead to the gelators build up of the same aggregates through similar hydrogen-bonding patterns. When two gelators with structurally different gelation-driving segments induce gelation, the gelators build up each aggregate through individual hydrogen-bonding patterns. A fluorescent reagent that was incorporated into the aggregates of gels through van der Waals interactions was developed. The addition of this fluorescent reagent enables the successful observation of nonfluorescent gelators' aggregates by FM.ArticleCHEMISTRY-A EUROPEAN JOURNAL.22(47):16937-16947(2016)journal articl

Nucleation process in the Burridge-Knopoff model of earthquakes

Nucleation process of the one-dimensional Burridge-Knopoff model of earthquakes obeying the rate- and state-dependent friction law is studied both analytically and numerically. The properties of the nucleation dynamics, the nucleation lengths and the duration times are examined together with their continuum limits.Comment: Title changed, one figure (previous Fig.2) omitted, several references (new Refs.5-8,21,24-28) added, and two eqs. (new eqs.1,5) added. Text expanded considerably, especially the part explaining the relation of the model to the elastic continuum model. To appear in Europhys. Letter

Topological classification of vortex-core structures of spin-1 Bose-Einstein condensates

We classify vortex-core structures according to the topology of the order parameter space. By developing a method to characterize how the order parameter changes inside the vortex core. We apply this method to the spin-1 Bose-Einstein condensates and show that the vortex-core structures are classified by winding numbers that are locally defined in the core region. We also show that a vortex-core structure with a nontrivial winding number can be stabilized under a negative quadratic Zeeman effect.Comment: 16 pages, 6 figure