胃癌高リスク群を対象とした早期胃癌の発見における第二世代狭帯域光観察の効果についての多施設ランダム化比較試験

京都大学0048新制・論文博士博士(医学)乙第13388号論医博第2220号新制||医||1048(附属図書館)(主査)教授 羽賀 博典, 教授 佐藤 俊哉, 教授 妹尾 浩学位規則第4条第2項該当Doctor of Medical ScienceKyoto UniversityDFA

Appearance of similar triangles by certain operations on triangles

In this paper, a theorem about similar triangles is proved. It shows that two small and four large triangles similar to the original triangle can appear if we choose well among several intersections of the perpendicular bisectors of the sides with perpendicular lines of sides passing through the vertices of the triangle

Ecological Dynamics of Broad- and Narrow-Host-Range Viruses Infecting the Bloom-Forming Toxic Cyanobacterium Microcystis aeruginosa

アオコ感染性広域・狭域宿主ウイルスの動態 --アオコとウイルスはいかに共存するか--. 京都大学プレスリリース. 2023-02-24.Microcystis aeruginosa is predicted to interact and coexist with diverse broad- and narrow-host-range viruses within a bloom; however, little is known about their affects on Microcystis population dynamics. Here, we developed a real-time PCR assay for the quantification of these viruses that have different host ranges. During the sampling period, total Microcystis abundance showed two peaks in May and August with a temporary decrease in June. The Microcystis population is largely divided into three phylotypes based on internal transcribed sequences (ITS; ITS types I to III). ITS I was the dominant phylotype (66% to 88%) except in June. Although the ITS II and III phylotypes were mostly less abundant, these phylotypes temporarily increased to approximately equivalent abundances of the ITS I population in June. During the same sampling period, the abundances of the broad-host-range virus MVGF_NODE331 increased from April to May and from July to October with a temporary decrease in June, in which its dynamics were in proportion to the increase of total Microcystis abundances regardless of changes in host ITS population composition. In contrast, the narrow-host-range viruses MVG_NODE620 and Ma-LMM01 were considerably less abundant than the broad-host-range virus and generally did not fluctuate in the environment. Considering that M. aeruginosa could increase the abundance and sustain the bloom under the prevalence of the broad-host-range virus, host abundant and diverse antiviral mechanisms might contribute to coexistence with its viruses

A Water-Free ITIES: Ionic Liquid/Oil Interface for Base Metal Nanostructure Formation - Zn Case

Reductive metal deposition at the interface between two immiscible electrolyte solutions (ITIES), the oil/water interface, is an attractive methodology to produce metal nanostructures. However, the metals that can be deposited are limited to noble metals; otherwise, water molecules are reduced. Herein, a method to overcome this limitation by utilizing a novel water-free ITIES between a hydrophilic ionic liquid and oil was introduced. As proof-of-concept experiments, the reductive deposition of zinc, a base metal with a standard redox potential more negative than that of water, was successfully realized at the ionic liquid/oil interface. The morphology of the zinc nanostructures was investigated, and the reaction mechanism was discussed, in which the electron transfer and ion transfer reactions across the interface simultaneously occurred to maintain the electroneutrality of the liquids

Isotopic fractionation of water during snow formation: Experimental evidence of kinetic effect

Deuterium excess(d-excess=δD-8・δ^(18)O), which is calculated using two water isotope ratios(δD and δ^(18)O), is an indicator of kinetic isotope fractionation. The d-excess value reflects the evaporation process from the ocean or ice-crystal growth. Consequently, d-excess records preserved in ice cores may provide a climatic history of ocean surface conditions at the vapor source area. J. Jouzel and L. Merlivat(J. Geophys. Res., 89, 11749, 1984) proposed an isotope model to analyze information from ice cores. That model includes kinetic fractionation during snow formation, depending on the degree of the supersaturation ratio of vapor. However, no experiment was conducted under the controlled supersaturation ratio. Experiments described herein measured the isotopic ratios of the vapor and artificial snow produced under a controlled supersaturation ratio to confirm the kinetic isotope effect experimentally. Results indicate a higher d-excess value for ice crystals at a higher vapor supersaturation ratio and provide experimental evidence for the kinetic effect during snow formation

Source identification of N2O produced during simulated wastewater treatment under different oxygen conditions using stable isotopic analysis

Nitrous oxide (N2O), a potent greenhouse gas which is important in climate change, is predicted to be the most dominant ozone depleting substance. It is mainly produced by oxidation of hydroxylamine (NH2OH) or reduction of nitrite (NO2-) during microbiological processes such as nitrification and denitrification. Wastewater treatment plant (WWTP) is one of the anthropogenic N2O sources because inorganic and organic nitrogen compounds are converted to nitrate (NO3-, in the case of standard system) or N2 (in the case of advanced system) by bacterial nitrification and denitrification in WWTP. We investigated the N2O production mechanisms during batch experiments that simulate wastewater treatment with activated sludge under various dissolved oxygen (DO) concentrations by stable isotope analysis. About 125mL of water was sampled from 30L incubation chamber for several times during the incubation, and concentration and isotopomer ratios of N2O and N-containing species were measured using gas chromatography/isotope ratio mass spectrometry (GC/IRMS). Ammonium (NH4+) consumption was accompanied by increment of nitrite (NO2-), and at the same time dissolved N2O concentration gradually increased to 4850 and 5650 nmol kg-1, respectively, during the four-hour incubation when DO concentrations were 0.2 and 0.5 mg L-1. Observed low SP values (0.2-8.9‰ at DO-0.2 mg L-1, -5.3-6.3‰ at DO-0.5 mg L-1, -1.0-8.3‰ at DO-0.8 mg L-1) in N2O and relationship of nitrogen isotope ratios between N2O and its potential substrates (NH4+, NO3-) suggested that N2O produced under the aerobic condition derived mainly from NO2- reduction by ammonia-oxidizing bacteria (nitrifier–denitrification).DOI: http://doi.dx.org/10.5564/mjc.v15i0.313Mongolian Journal of Chemistry  15 (41), 2014, p4-10