Boronic acid-catalyzed regioselective Koenigs− Knorr-type glycosylation is presented. The reaction of an unprotected or partially protected glycosyl acceptor with a glycosyl halide donor in the presence of silver oxide and a low catalytic amount of imidazole-containing boronic acid was found to proceed smoothly, which enables construction of a 1,2-trans glycosidic linkage with high regioselectivities. This is the first example of the use of a boronic acid catalyst to initiate regioselective glycosylation via the activation of cis-vicinal diols in glycosyl acceptors. Note pubs.acs.org/joc

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In motor drive applications, a high switching frequency is required to mitigate current harmonics, which cause a copper loss. However, the high switching frequency makes the switching loss large. Hence, some switching loss reduction techniques have been studied in the past. These techniques have some problems. This paper proposes a multilevel inverter topology for switching loss reduction. Because of provision of multiple current paths, the proposed inverter realizes the zero current switching. Consequently, a loss of the whole system including an inverter and motor can be reduced with a higher switching frequency. The switching loss of the proposed inverter is smaller than that of the conventional one. It was verified that the proposed inverter has some advantages at high switching frequency, through calculations.

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Hydrothermal processes associated with spreading centers of plate-tectonic activity form seafloor massive sulfide (SMS) deposits. Given that the SMS deposits found in the western Pacific have been considered to be potential sources of gold (Au), silver (Ag), cupper (Cu), zinc (Zn), and lead (Pb) including manganese nodules and cobalt-rich manganese crusts, there is a strong possibility that they will be mined in near future. In order to take measures against environmental impact during the mining of SMS deposits, it is important to measure components of hydrothermal origin with high temporal and spatial resolution on site, and to understand the ecosystem in the hydrothermal environment. In this study, we first propose a measurement method of turbidity profiles using an Acoustic Doppler Current Profiler (ADCP). Applying this method to the ADCP measurements in the Izena Calderon with SMS in the Okinawa Trough, we verify that this method can extract turbidity data from echo intensities measured by ADCP. Subsequently, we describe the high-turbidity water in the Izena Calderon measured by ADCP, and present and discuss the turbidity fluctuations estimated by applying time-frequency analysis to these turbidity data.