We observed that Faraday waves are parametrically generated on a free surface of superfluid 4He when a sample cell is vibrated vertically. Standing-wave patterns appear on the surface, and their frequencies are one-half the driving frequency. We observed clear threshold amplitudes of the vibration for the instability. The difference in the threshold between the superfluid and the normal fluid is explained by a wall damping.

Polar H 2 O molecules generally act as trapping sites and suppress the electron mobility of n-type organic semiconductors, making chemical design of H 2 O-tolerant and responsive n-type semiconductors an important step toward multifunctional electron−ion coupling devices. The introduction of effective electrostatic interactions between potassium ions (K + ) and carboxylate (−COO − ) anions into the electron-transporting naphthalenediimide πframework enables the design of high-performance H 2 O-tolerant n-type semiconductors with a reversible H 2 O adsorption−desorption ability, where the electron mobility and K + ionic conductivity were coupled with the reversible H 2 O sorption behavior. The reversible H 2 O adsorption into the crystals enhanced the electron mobility from 0.04 to 0.28 cm 2 V −1 s −1 , whereas the K + ionic conductivity decreased from 3.4 × 10 −5 to 4.7 × 10 −7 S cm −1 . Because this reversible electron−ion conducting switch is responsive to H 2 O sorption behavior, it is a strong candidate for H 2 O gating carrier transport systems.

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which exhibited reversible H 2 O adsorption−desorption behavior because of the presence of their electrostatically binding crystal lattices. The maximum H 2 O adsorption amounts (n) for M + = Li + , Na + , K + , Rb + , and Cs + were 0.25, 6.0, 4.0, 6.0, and 2.0, respectively, whereas the reversible gate-opening (gateclosing) H 2 O adsorption−desorption isotherms were observed at 273 and 298 K, except for M + = Li + . High ionic conductivities of around 10 −4 −10 −5 S cm −1 were observed in M + = Na + and K + salts, whereas short-range thermal fluctuations occurred in large cations of M + = Rb + and Cs + . The change in the electrostatic lattice energy for M + = Na + and K + salts during the H 2 O adsorption−desorption cycles was significantly larger than those for M + = Rb + and Cs + . Therefore, the Na + and K + salts had a considerably flexible electrostatic crystal lattice with a large amplitude of lattice modulation during the H 2 O sorption cycle. In contrast, the lattice modulation for M + = Rb + and Cs + salts involved a low magnitude of ion displacements, forming a relatively rigid cation−anion electrostatic crystal lattice. The flash-photolysis time-resolved microwave conductivity and transition absorption spectroscopy results revealed the high electron mobility of H 2 O-adsorbed thin films, wherein the crystallized H 2 O molecules did not act as electron-trapping sites. The values of electron mobility increased in the order of Cs

This paper reports on measurements of in-plane thermal conductivities, electrical conductivities, and Lorentz number of two microfabricated, suspended, nanosized thin films with a thickness of 28 nm. The effect of the film thickness on the in-plane thermal conductivity is examined by measuring other nanofilm samples with a thickness of 40 nm. The experimental results show that the electrical conductivity, resistance-temperature coefficient, and in-plane thermal conductivity of the nanofilms are much smaller than the corresponding bulk values from 77 to 330 K. However, the Lorentz number of the nanofilms is about two times that of the bulk value at room temperature, and even up to three times that of the bulk value at 77 K. These results indicate that the relation between the thermal conductivity and electrical conductivity of the nanofilms does not follow the Wiedemann-Franz law for bulk metallic materials.

Very fast growth of the c-facet of a 4 He crystal was induced by acoustic waves. The growth velocity was larger at lower temperatures and saturated below about 400 mK. The velocity was proportional to the acoustic wave power. This fast growth cannot be explained by the spiral growth mechanism for the known value of the step mobility. We developed a step multiplication model for high-power acoustic waves and found reasonable agreement with the observed temperature and power dependence of the growth velocity.KEYWORDS: quantum solids, superfluid, acoustic radiation pressure, crystal growth, step DOI: 10.1143/JPSJ.75.023601A fundamental problem in crystal growth physics is how fast a facet can grow. In ordinary materials, the facet grows with a spiral growth mechanism well below the roughening transition temperature. 1) Step motion is limited by the diffusion of atoms and/or by the transport of latent heat. When two steps with opposite sign collide, they disappear without any reflection or transmission.Step density cannot increase indefinitely but reaches a steady-state value which is determined by the driving force for the crystallization. Recently, Parshin and Tsymbalenko have proposed a new type of collision of steps in the case of high mobility of steps at a large driving force.2) When high speed-steps collide, the steps pass through each other making another atomic layer on the facet due to the inertia of the liquid accompanying the step motion. This kinematical multiplication of steps makes the step density higher and the growth of the facet faster. Mobility of steps for a 4 He crystal in the superfluid liquid is not limited by the diffusion and can be very high at very low temperatures.3) We observed anomalously fast growth of the c-facet of a 4 He crystal induced by acoustic waves. The fast growth could not be explained by the spiral growth mechanisms and we possibly observed the multiplication of steps.We reported that acoustic waves induce crystallization of 4 He crystals at low temperatures. 4,5) We interpreted that this interface motion was induced by the acoustic radiation pressure. For the small displacement of the interface by a short acoustic wave pulse (1 ms), the acoustic radiation pressure model can explain the growth velocity of the rough and vicinal surfaces reasonably well at low temperatures by taking into account the orientation dependence of the growth coefficients. In this paper, we report the effect of the longer pulse (50 ms) applied to the vicinal surface from the crystal side. The displacement of the interface was much larger and the clear c-facet soon appeared on the top of the upheaval because the growth velocity of the c-facet was smaller than the vicinal surface. This growth velocity of the c-facet was much larger than the value expected from the spiral growth model with known step mobility. Since the pressure oscillation of the applied acoustic wave was large enough to accelerate steps to the velocity of sound, kinematical step multiplication was likely to occur. We constructed a g...

A ruthenium-catalyzed carbocyclization of 2-alkynylstyrenes that involves a very rare 1,2-carbon migration of internal alkynes is reported. Various 1,2-di -and 1,4,7-trisubstituted naphthalenes are synthesized. Mechanistic studies revealed that this reaction proceeds via a disubstituted vinylidene complex as the key intermediate by 1,2-carbon migration of the 2-alkynylstyrenes.

The global network of gravitational-wave observatories now includes five detectors, namely LIGO Hanford, LIGO Livingston, Virgo, KAGRA, and GEO 600. These detectors collected data during their third observing run, O3, composed of three phases: O3a starting in 2019 April and lasting six months, O3b starting in 2019 November and lasting five months, and O3GK starting in 2020 April and lasting two weeks. In this paper we describe these data and various other science products that can be freely accessed through the Gravitational Wave Open Science Center at https://gwosc.org. The main data set, consisting of the gravitational-wave strain time series that contains the astrophysical signals, is released together with supporting data useful for their analysis and documentation, tutorials, as well as analysis software packages.