Hiroaki Kobayashi

Heterogeneously Catalyzed Synthesis of Primary Amides Directly from Primary Alcohols and Aqueous Ammonia

In the presence of a manganese oxide based octahedral molecular sieve (OMS-2), a range of primary amides could be synthesized directly from primary alcohols and ammonia. The observed catalysis was heterogeneous, and the recovered catalyst could be reused many times without an appreciable loss of its catalytic performance.

Green oxidative synthesis of primary amides from primary alcohols or aldehydes catalyzed by a cryptomelane-type manganese oxide-based octahedral molecular sieve, OMS-2

In this study, a new green synthetic route to primary amides, that is, aerobic oxidative amidation of primary alcohols or aldehydes with ammonia, has been developed. In the presence of a cryptomelane-type manganese oxide-based octahedral molecular sieve (OMS-2), various kinds of structurally diverse primary alcohols or aldehydes including aromatic, olefinic, heteroaromatic, and aliphatic ones can be converted into the corresponding primary amides in moderate to high yields (20 examples from primary alcohols and 11 examples from aldehydes). Furthermore, gram-scale amidation is also effective, and the analytically pure primary amides can easily be isolated. The present catalysis by OMS-2 is truly heterogeneous in nature, and the retrieved OMS-2 catalyst can be reused several times (at least 12 times for the amidation of 2-pyridinemethanol). Though the formation rates of the corresponding primary amide are gradually decreased by repeating reuse experiments, OMS-2 can be regenerated by calcination. The present OMS-2-catalyzed amidation of primary alcohols is composed of four relay steps: (i) oxidative dehydrogenation of primary alcohols, (ii) dehydrative condensation of aldehydes with ammonia, (iii) oxidative dehydrogenation of aldimines, and (iv) hydration of nitriles to form the corresponding primary amides. All steps (i)–(iv) can be promoted by the presence of OMS-2.

Non-inductive plasma current start-up by EC and RF power in the TST-2 spherical tokamak

Non-inductive plasma current start-up by EC and RF power was carried out on the TST-2 device. Low frequency RF (21 MHz) sustainment was demonstrated, and the obtained high βp spherical tokamak configuration has similar equilibrium values as the EC (2.45 GHz) sustained plasma. Equilibrium analysis revealed detailed information on three discharge phases: (i) in the initial current formation phase, the plasma current increases with the stored energy, and the current is in the same order as that predicted by theory. (ii) In the current jump phase, the current density profile, which is peaked near the outboard boundary, is not deformed but increases slowly and the initial closed flux surface appears when the current reaches a maximum. (iii) In the current sustained phase, equilibrium is characterized by the hollowness of the current density profile, and it determines the fraction of the current inside the last closed flux surface to the total current. Both EC and RF injections show a similar equilibrium. While MHD instabilities often terminate the RF sustained plasma, no such phenomenon was observed in the EC sustained plasma.

Widespread ground motion distribution caused by rupture directivity during the 2015 Gorkha, Nepal earthquake

The ground motion and damage caused by the 2015 Gorkha, Nepal earthquake can be characterized by their widespread distributions to the east. Evidence from strong ground motions, regional acceleration duration, and teleseismic waveforms indicate that rupture directivity contributed significantly to these distributions. This phenomenon has been thought to occur only if a strike-slip or dip-slip rupture propagates to a site in the along-strike or updip direction, respectively. However, even though the earthquake was a dip-slip faulting event and its source fault strike was nearly eastward, evidence for rupture directivity is found in the eastward direction. Here, we explore the reasons for this apparent inconsistency by performing a joint source inversion of seismic and geodetic datasets, and conducting ground motion simulations. The results indicate that the earthquake occurred on the underthrusting Indian lithosphere, with a low dip angle, and that the fault rupture propagated in the along-strike direction at a velocity just slightly below the S-wave velocity. This low dip angle and fast rupture velocity produced rupture directivity in the along-strike direction, which caused widespread ground motion distribution and significant damage extending far eastwards, from central Nepal to Mount Everest.

Parametric decay instability during high harmonic fast wave heating experiments on the TST-2 spherical tokamak

A degradation of heating efficiency was observed during high harmonic fast wave (HHFW) heating of spherical tokamak plasmas when parametric decay instability (PDI) occurred. Suppression of PDI is necessary to make HHFW a reliable heating and current drive tool in high ? plasmas. In order to understand PDI, measurements were made using a radially movable electrostatic probe (ion saturation current and floating potential), arrays of RF magnetic probes distributed both toroidally and poloidally, microwave reflectometry and fast optical diagnostics in TST-2. The frequency spectrum usually exhibits ion-cyclotron harmonic sidebands f0 ? nfci and low-frequency ion-cyclotron quasi-modes (ICQMs) nfci. PDI becomes stronger at lower densities, and much weaker when the plasma is far away from the antenna. The lower sideband power was found to increase quadratically with the local pump wave power. The lower sideband power relative to the local pump wave power was larger for reflectometer compared with either electrostatic or magnetic probes. The radial decay of the pump wave amplitude in the SOL was much faster for the ion saturation current than for the floating potential. These results are consistent with the HHFW pump wave decaying into the HHFW or ion Bernstein wave (IBW) sideband and the low-frequency (ICQM). Two additional peaks were discovered between the fundamental lower sideband and the pump wave in hydrogen plasmas. The frequency differences of these peaks from the pump wave increase with the magnetic field. These decay modes may involve molecular ions or partially ionized impurity ions.

Rupture processes of the 2016 Kumamoto earthquake sequence: Causes for extreme ground motions

We performed joint inversions of strong motion, teleseismic, and geodetic data to investigate the rupture processes of three notable (Mw ≥ 6.0) events of the 2016 Kumamoto earthquake sequence. Multi-segment fault models for the three events were constructed based on focal mechanisms, hypocenter distributions of this sequence, and active faults, as well as geodetic features. The results reveal the spatial relationships between the slip distributions of the three events over complex fault planes. In the largest event, the rupture primarily propagated to a northeastern region along the Futagawa fault zone. The extreme pulse-like waveforms observed at the near-fault stations during the largest event can be attributed to the events upward rupture directivity, slip rate, and the nearly simultaneous slip of two subparallel fault planes.

Joint inversion of teleseismic, geodetic, and near-field waveform datasets for rupture process of the 2015 Gorkha, Nepal, earthquake

The 2015 Gorkha earthquake and its aftershocks caused severe damage mostly in Nepal, while countries around the Himalayan region were warned for decades about large Himalayan earthquakes and the seismic vulnerability of these countries. However, the magnitude of the Gorkha earthquake was smaller than those of historical earthquakes in Nepal, and the most severe damage occurred in the north and northeast of Kathmandu. We explore reasons for these unexpected features by performing a joint source inversion of teleseismic, geodetic, and near-field waveform datasets to investigate the rupture process. Results indicate that the source fault was limited to the northern part of central Nepal and did not reach the Main Frontal Thrust. The zone of large slip was located in the north of Kathmandu, and the fault rupture propagated eastward with an almost constant velocity. Changes in the Coulomb failure function (ΔCFF) due to the Gorkha earthquake were computed, indicating that southern and western regions neighboring the source fault are potential source regions for future earthquakes related to the Gorkha earthquake. These two regions may correspond to the historical earthquakes of 1866 and 1344. Possible future earthquakes in the regions are predicted, and the warning for Himalayan seismic hazards remains high even after the Gorkha earthquake.

Design and control methodology for fine grain power gating based on energy characterization and code profiling of microprocessors

This paper presents a design and control scheme of a microprocessor whose internal function units are power gated at instruction-by-instruction basis. Enabling/disabling the power gating is adaptively controlled under the support of on-chip leakage monitors and the operating system to minimize energy overhead due to sleep-in and wakeup. Measured results of the fabricated chip in the 65nm CMOS technology demonstrated that our approach reduces energy to 21-35% in the range of 25-85°C as compared to the non power-gated case. Energy dissipation was reduced by up to 15% as compared to the conventional fine-grain power gating technique in the same temperature range.

Equilibrium Analysis of EC‐Sustained and RF‐Sustained ST Plasmas

Plasma current start‐up and formation of the ST configuration without the use of the central solenoid is a critical issue in ST research. In the TST‐2 spherical tokamak (R = 0.38 m, a = 0.25 m), sustainment of an ECRF (2.45 GHz) produced ST plasma by low frequency (21 MHz) RF power alone was demonstrated. Since direct RF current drive can be ruled out, this result implies that the ST configuration is sustained entirely by pressure‐driven currents. The Grad‐Shafranov equilibrium was generalized to take into account the open field line region with finite plasma current and pressure (truncated equilibrium). In addition to the precessional current of trapped particles, Pfirsch‐Schluter current flowing along the open field line (and partially returning through the vacuum vessel) contributes to the toroidal plasma current. Three phases of plasma start‐up are analyzed: (i) the current formation phase, (ii) the current jump phase, and (iii) the current sustainment phase. In the current formation phase, the plasma...

High Harmonic Fast Wave experiments on TST‐2 and UTST

HHFW experiments on TST‐2 and UTST were performed. In the TST‐2 HHFW experiment, the pickup probe mounted on the inboard wall detected the same PDI lower sideband peak as probes on the outboard side. Since the frequency difference from the pump wave corresponds to the ion cyclotron frequency on the low field side, the lower sideband wave is believed to be generated at the plasma edge on the low field side, and propagated to the high field side. This component may be the FW. In the UTST HHFW experiment, direct measurements of the RF fields in the plasma were made successfully.