Tip-sample distance control using photothermal actuation of a small cantilever for high-speed atomic force microscopy

We have applied photothermal bending of a cantilever induced by an intensity-modulated infrared laser to control the tip-surface distance in atomic force microscopy. The slow response of the photothermal expansion effect is eliminated by inverse transfer function compensation. By regulating the laser power and regulating the cantilever deflection, the tip-sample distance is controlled; this enables much faster imaging than that in the conventional piezoactuator-based z scanners because of the considerably higher resonant frequency of small cantilevers. Using this control together with other devices optimized for high-speed scanning, video-rate imaging of protein molecules in liquids is achieved.     

On‐Demand Control of the Photochromic Properties of Naphthopyrans

Photofunctional compounds have emerged as critically important materials for both fundamental studies and industrial applications. Control of the thermal decoloration speed to within several seconds while sustaining satisfactory photochromic colorability is an important challenge for the application of such materials to photochromic lenses and smart windows. Photochromic naphthopyran derivatives are utilized for photochromic lenses because of their high durability and easily controllable colorability. However, the residual color imparted by the long‐lived transient species upon ceasing light irradiation remains a hindrance to practical applications. In this study, a strategy is demonstrated for on‐demand control of the thermal decoloration speed of the transient colored species of naphthopyran derivatives. The increase in the ring‐size of the alkylenedioxy moiety on the naphthopyrans accelerates the thermal back‐reaction independently of the maximum‐absorption wavelength of the colored isomer, leading to the realization of yellow‐, red‐, and blue‐photochromic naphthopyrans with similar thermal fading speeds. This novel molecular design provides a strategy for the future development of advanced photoresponsive materials.     

Local structural arrangements around oxygen and hydrogen-related defects in proton conducting LaP3O9 investigated by first principles calculations

Local structural arrangements and stabilities of oxygen and hydrogen-related defects in proton-conducting LaP₃O₉ were studied using first principles calculations. When an oxygen was removed from LaP₃O₉, the crystal lattice was significantly distorted. Resulting structural arrangements considerably depended on the oxygen deficient site, and phosphate ions tended to condense by sharing a corner oxygen of PO₄ tetrahedra. On the other hand, when a proton was introduced, the proton was located at the interstitial sites positioned approximately 1 Å away from the nearest oxygen forming an O–H bond. The LaP₃O₉ lattice was only slightly distorted even after introduction of an interstitial proton. Based on the calculation results, the stabilities of the defects under moisturized conditions was discussed.     

Multi-color light-emitting transistors composed of organic single crystals

We report a novel concept for multi-color light emission from an ambipolar organic single-crystal transistor using natural optical waveguides, the self-absorption effect, Davydov splitting and the unique alignment of the transition dipole moments. We used 9,10-bis-(2,2-diphenylvinyl)-anthracene single crystals to produce blue and green light from identical single-crystal transistors. We also observed red light, which corresponds to the emission from in-gap states that are caused by impurities. Importantly, each of these different colors corresponds to a distinguishable light polarization, which enables us to tune the emission color by using a light polarizer.     

Algorithmic randomness and monotone complexity on product space

We study algorithmic randomness and monotone complexity on product of the set of infinite binary sequences. We explore the following problems: monotone complexity on product space, Lambalgen’s theorem for correlated probability, classification of random sets by likelihood ratio tests, decomposition of complexity and independence, and Bayesian statistics for individual random sequences. Formerly Lambalgen’s theorem for correlated probability is shown under a uniform computability assumption in [H. Takahashi Inform. Compt. 2008]. In this paper we show the theorem without the assumption.     

Safe operation of an autonomous underwater towed vehicle: Towed force monitoring and control

On underwater towed systems, the towing cable plays an important role in transmitting electric signals and towing forces. Hence, it is strongly recommended to monitor the towed force for preventing cable breaks and making use of it more efficiently; however, most existing underwater towed systems do not have such a capability. This paper discusses towed force monitoring and control for safe operation of an autonomous towed vehicle that is a kind of autonomous underwater vehicle (AUV). We first overview the autonomous towed vehicle and describe our related previous works. We then present our towed force measuring and monitoring manners and an experimental methodology for obtaining the feasible range of the towed force. In addition, towed force estimation only with vehicle dynamics is presented for the case when the towed force sensor became useless. Finally, we discuss towed force control to keep the towed force inside its feasible region.     

Organocatalyst‐Mediated Dehydrogenation of Aldehydes to α,β‐Unsaturated Aldehydes,and Oxidative and Enantioselective Reaction of Aldehydes and Nitromethane Catalyzed by Diphenylprolinol Silyl Ether

A one‐pot transformation of aldehydes into α,β‐unsaturated aldehydes was developed using both N‐benzyl‐N‐methylamine and 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) as catalysts and MnO₂ as a terminal oxidant. An oxidative and enantioselective reaction of aldehydes and nitromethane was established using both diphenylprolinol silyl ether and DDQ as a catalyst with MnO₂ as a terminal oxidant, in which synthetically important β‐substituted γ‐nitro aldehydes were obtained with excellent enantioselectivity.