Author
Jun Yamamoto
Other affiliations: National Institute of Advanced Industrial Science and Technology, Hirosaki University
Bio: Jun Yamamoto is an academic researcher from Kyoto University. The author has contributed to research in topics: Liquid crystal & Phase (matter). The author has an hindex of 20, co-authored 110 publications receiving 3346 citations. Previous affiliations of Jun Yamamoto include National Institute of Advanced Industrial Science and Technology & Hirosaki University.
Papers published on a yearly basis
Papers
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01 Jan 2014
TL;DR: In this paper, the authors describe the story of the recent developments and the future perspectives in physics of liquid crystals, especially focusing on the contributions by Japanese research groups for the last decade, and present new subjects unmentioned in the book.
Abstract: Over the 100 years since its discovery, liquid crystals have been the intriguing subject for both academia and industries. The textbook of de Gennes The Physics of Liquid Crystals published in 1974 is still the bible for many LC researchers, but new subjects unmentioned in the book have also risen for these years. This chapter describes the story of the recent developments and the future perspectives in physics of liquid crystals, especially focusing on the contributions by Japanese research groups for the last decade.
2,005 citations
TL;DR: This work introduces two different types of spatial distributions of forces, detected between the particles accompanied by hyperbolic hedgehog defects, which lead to specific particle arrangements, which are stabilized by the balance of the orientational stress field of nematics.
Abstract: Interparticle forces in a nematic liquid-crystal colloid have been directly observed by the dual beam laser trapping method with pN sensitivity. We introduce two different types of spatial distributions of forces, detected between the particles accompanied by hyperbolic hedgehog defects. These force distributions lead to specific particle arrangements, which are both stabilized by the balance of the orientational stress field of nematics. On the basis of these results, we propose novel artificial construction for multiparticle regular arrangements.
187 citations
TL;DR: In this article, a robust in-plane bistability of liquid-crystal surface alignment based on tailored submicrometer-sized surface domains imposing a frustrated alignment was demonstrated.
Abstract: We demonstrate a robust in-plane bistability of liquid-crystal surface alignment based on tailored submicrometer-sized surface domains imposing a frustrated alignment. By a nanorubbing technique utilizing the atomic force microscope, we prepared an orientational checkerboard pattern on polyimide layer, consisting of square unit domains on which the alignment is locally constrained to be planar yet orthogonal between the neighboring domains. Due to the four-fold rotational symmetry of the pattern, the two diagonal axes of the square domain become equally stable directions for the macroscopic liquid crystal alignment. The alignment could be switched between these two states by an in-plane electric field above a certain threshold, determined by the local azimuthal anchoring.
108 citations
TL;DR: New chiral dimers consisting of a rod-like and cholesterol mesogenic units are reported to form a chiral twist-bend nematic phase (NTB *) with heliconical structure, which is consistent with the nanoperiodic structure of the NTB phase.
Abstract: New chiral dimers consisting of a rod-like and cholesterol mesogenic units are reported to form a chiral twist-bend nematic phase (NTB*) with heliconical structure. The compressibility of the NTB phase made of bent dimers was found to be as large as in smectic phases, which is consistent with the nanoperiodic structure of the NTB phase. The atomic force microscopy observations in chiral bent dimers revealed a periodicity of about 50 nm, which is significantly larger than the one reported previously for non-chiral compounds (ca. 10 nm).
99 citations
TL;DR: In this paper, a binaphthyl derivative possessing two 2,3-difluoro-1,4-diphenylbenzene units was prepared and the phase transition behavior was investigated.
Abstract: We prepared a binaphthyl derivative possessing two 2,3-difluoro-1,4-diphenylbenzene units, and then investigated the phase transition behaviour. On cooling, the compound was found to exhibit a phase sequence of iso liq–blue phase–smectic phase. The temperature of the blue phase with a cubic structure was about 30 K. An electric-field-induced phase transition was observed in the blue phase. On heating, the compound exhibited marked phase separation. Some regions showed a phase sequence of cryst–chiral nematic (N*)–blue phase (BP)–iso liq, whereas others showed that of cryst–iso liq. The temperature range of coexisting crystal and iso liq phases was about 29 K. The phase separation is quite unusual for a single compound. The phase-transition behaviour is discussed in terms of the molecular shape of the binaphthyl derivative.
91 citations
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01 Jan 2014
TL;DR: In this paper, the authors describe the story of the recent developments and the future perspectives in physics of liquid crystals, especially focusing on the contributions by Japanese research groups for the last decade, and present new subjects unmentioned in the book.
Abstract: Over the 100 years since its discovery, liquid crystals have been the intriguing subject for both academia and industries. The textbook of de Gennes The Physics of Liquid Crystals published in 1974 is still the bible for many LC researchers, but new subjects unmentioned in the book have also risen for these years. This chapter describes the story of the recent developments and the future perspectives in physics of liquid crystals, especially focusing on the contributions by Japanese research groups for the last decade.
2,005 citations
TL;DR: A record of sedimentation in Laguna Pallcacocha, southern Ecuador, which is strongly influenced by ENSO variability, and covers the past 12,000 years continuously is presented, finding that changes on a timescale of 2–8 years become more frequent over the Holocene until about 1,200 years ago, and then decline towards the present.
Abstract: The variability of El Nino/Southern Oscillation (ENSO) during the Holocene epoch, in particular on millennial timescales, is poorly understood. Palaeoclimate studies have documented ENSO variability for selected intervals in the Holocene, but most records are either too short or insufficiently resolved to investigate variability on millennial scales1,2,3. Here we present a record of sedimentation in Laguna Pallcacocha, southern Ecuador, which is strongly influenced by ENSO variability, and covers the past 12,000 years continuously. We find that changes on a timescale of 2–8 years, which we attribute to warm ENSO events, become more frequent over the Holocene until about 1,200 years ago, and then decline towards the present. Periods of relatively high and low ENSO activity, alternating at a timescale of about 2,000 years, are superimposed on this long-term trend. We attribute the long-term trend to orbitally induced changes in insolation, and suggest internal ENSO dynamics as a possible cause of the millennial variability. However, the millennial oscillation will need to be confirmed in other ENSO proxy records.
1,534 citations
TL;DR: The purpose of this review is to convey the fundamentals of droplet microfluidics, a critical analysis on its current status and challenges, and opinions on its future development.
Abstract: Droplet microfluidics generates and manipulates discrete droplets through immiscible multiphase flows inside microchannels Due to its remarkable advantages, droplet microfluidics bears significant value in an extremely wide range of area In this review, we provide a comprehensive and in-depth insight into droplet microfluidics, covering fundamental research from microfluidic chip fabrication and droplet generation to the applications of droplets in bio(chemical) analysis and materials generation The purpose of this review is to convey the fundamentals of droplet microfluidics, a critical analysis on its current status and challenges, and opinions on its future development We believe this review will promote communications among biology, chemistry, physics, and materials science
990 citations
TL;DR: This review collects recent developments in the field of liquid crystalline elastomers with an emphasis on their use for actuator and sensor applications and how these materials can be turned into usable devices using different interdisciplinary techniques.
Abstract: This review collects recent developments in the field of liquid crystalline elastomers (LCEs) with an emphasis on their use for actuator and sensor applications. Several synthetic pathways leading to crosslinked liquid crystalline polymers are discussed and how these materials can be oriented into liquid crystalline monodomains are described. By comparing the actuating properties of different systems, general structure-property relationships for LCEs are obtained. In the final section, how these materials can be turned into usable devices using different interdisciplinary techniques are described.
871 citations
TL;DR: In this paper, the authors introduce the concept of rogue waves, which is the name given by oceanographers to isolated large amplitude waves, that occur more frequently than expected for normal, Gaussian distributed, statistical events.
851 citations