S. Itoh

Efficient construction of indole rings from 2-ethynylaniline derivatives catalyzed by copper(II) salts and its application to the tandem cyclization reactions

Abstract The efficient cyclization reactions of the N -methanesulfonyl or N -ethoxycarbonyl derivatives of 2-ethynylanilines, functionalized on the benzene ring and/or the acetylene terminal into indoles catalyzed by either Cu(OTf) 2 or Cu(OAc) 2 are accomplished. The application of this reaction to the tandem cyclization reaction is also described.

Development of a WDX-μ-PIXE system for chemical state mapping

In this paper, we have developed a wavelength dispersive X-ray spectrometer microparticle-induced X-ray emission (WDX-μ-PIXE) system combining a microbeam system with high spatial resolution and wavelength dispersive X-ray (WDX) spectrometry with high-energy resolution for chemical state mapping. A Von Hamos geometry was used for the WDX system to achieve higher detection efficiency and energy resolution. The system consists of a curved crystal and a CCD camera. The WDX system was installed in a newly developed microbeam system. The energy resolution of the WDX system was 0.67 eV for Si-Kα1 (1740 eV). Si-Kα1,2 and Si-Kβ X-ray spectra from various Si compounds were measured and chemical shifts related to chemical states were clearly observed. The system was applied to the chemical state analysis of clay particles. After elemental mapping of the clay particles using a conventional μ-PIXE system with a Si(Li) detector, particles to be analyzed were selected and analyzed sequentially with the WDX system. Si-Kβ spectra from clay particles were obtained. The microscopic spatial distribution of elements and chemical state of the clay particles were sequentially measured with high energy and spatial resolution using a microbeam.

Measurement of distributions of cesium and rubidium in rice grains using micro-PIXE for detailed examinations of contaminated food

We used micro-PIXE to investigate the distribution of Cs and Rb in rice grains. We succeeded, for the first time, in measuring the elemental distributions in entire rice grains (with dimensions of 6.25 mm × 6.25 mm) at micrometer spatial resolution. We found that Cs and Rb accumulated in the bran and germ of the rice. The distributions of P, K, Rb and Cs were similar within the rice grain. The concentrations of Cs and Rb in the rice were proportional to those in the soil, as well as to the exposure time. The uptake of Rb was significantly larger than that of Cs. Furthermore, the behavior of Rb was similar to that of Cs in the micrometer-scale regions in plants. It follows that the distribution of Rb can be used to investigate the behavior of radioactive Cs in plants.

Micro-PIXE analysis of the distribution of cesium in clay particles for environmental remediation of Fukushima

The Fukushima Daiichi nuclear power plant accident caused radioactive pollution by 131I, 134Cs and 137Cs. The surface of the ground was contaminated at a volume of 3 × 107 m3. The government has mandated that the top 5 cm of the contaminated soil be removed and stored, in this way, it is desirable to reduce its volume. Soil samples were collected from a mountain, a rice field and a vegetable field in northern Japan, and the silt was extracted from the muddy water by washing the soil. Next, the silt was sprayed with a solution of cesium carbonate (Cs2CO3). We determined the amounts of Al, Si, K and Cs in the silt particles using micro-particle-induced X-ray emission (micro-PIXE) analysis. The silt particles from a vegetable field, a rice field and a mountain were mainly formed from smectite or vermiculite, which absorbs Cs atoms. The measurements at multiple detection angles confirmed that Cs atoms were uniformly absorbed within silt particles less than 10−30 μm in diameter. This resulted that the radioactive Cs atoms were adsorbed in silt particles within 10−30 μm of the surface.

Development of a method for analyzing the composition of ambient PM2.5 floating dust particles by micro-PIXE

In this paper, we developed a technique for analyzing individual PM2.5 particles using micro-PIXE. PM2.5, a designation for extremely small particulate matter (PM) in the air, has recently become the center of attention because high levels of PM2.5 were recorded in parts of western Japan, especially Fukuoka Prefecture, in January 2013. For a better understanding of their formation mechanism, analysis of individual particles is indispensable. We collected PM2.5 on a 4 μm thick Prolene foil using a multi-nozzle cascade impactor at Fukuoka Women’s University, Fukuoka, Japan. Its elemental analysis was carried out using a micro-PIXE system at Tohoku University. Although elemental concentration ratios of scanned areas were similar, those of individual particles were quite different from each other. Elemental concentration ratios for individual particles were categorized into five groups, indicating that the PM2.5 particles came from at least five different sources. Although elemental concentrations obtained by averaging over single particles formed in different processes will lose detailed information, we were able to derive comprehensive elemental compositions of individual PM2.5 particles using our novel technique. The individual particle analysis technique for PM2.5 will provide important information to identify pollution sources and particle formation mechanisms.