POLYMERS Vol.71 No.10
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Le Polymère – Polymers That Think
COVER STORY: Highlight Reviews
Polymers in Neuromorphic Device and Technology Megumi AKAI-KASAYA
<Abstract> Artificial neural network uses a model that’s inspired by the workings of the brain, whereas the neuromorphic device is mimicking the functions of the neuron. The possibility of neuromorphic informational processing utilizing any response from devices, materials or physical substances is now attracting considerable attention. The number of reporting of neuromorphic polymer devices is now rapidly increasing in this research field. In this paper, the neural networks as artificial intelligence and neuromorphic functions are illustrated and explained in plain words, and synaptic polymer devices, namely, memristor and transistor, and their promising functions and future perspectives are concretely introduced.
Keywords: Artificial Neural Network / Reservoir Computing / Neuromorphic Device / Polymer / Synaptic Device / Memristor / Polymer Network / Electrolyte-Gated Polymer Transistors
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The Present and Future of Autonomous Molecular Computing Yusuke SATO, Jing GONG, Masahiro TAKINOUE
<Abstract> Nucleic acid molecules such as DNA and RNA are used as programmable molecular materials due to their sequence-specific binding ability. In structural DNA nanotechnology, from lattice structures fabricated from Nadrian Seeman’s Holiday Junction, static and dynamic structures of various dimensions and shapes can be easily obtained. In DNA computing, since the demonstration of a computing application using DNA molecules by Leonard Adleman, we have seen the development in medical applications, DNA storage, and DNA neural networks. Furthermore, the molecular computer called Reverse transcription and TRanscription-based Autonomous Computing System (RTRACS) and the DNA droplet computer, based on the physical phenomenon of liquid-liquid phase separation, are developed to demonstrate the autonomous and programmable computing ability. Molecular/DNA computing research can be inspired by electronic computers or intelligent molecular systems such as life, and all have broad potential for future development.
Keywords: DNA Nanotechnology / DNA Computing / Autonomous Molecular Computing / DNA Droplet Computer / RTRACS / DNA Storage / DNA Neural Networks / Liquid-Liquid Phase Separation
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Neuron-Mimicking Electronic Device Using Polymer Dynamics Naoki ASAKAWA
<Abstract> With the increasing use of the Internet of Things, there is a growing interest in artificial intelligence. Conventional digital computers operate deterministically, making it difficult for them to operate appropriately in environments that are not suitable for modeling or abrupt environment changes. Therefore, neuromorphic devices that mimic the nervous system are receiving attention. However, the biggest problem of conventional artificial neural networks is derived from its deterministic nature, and they lack the characteristic of adaptability to environmental changes. In this perspective, a mechanism of adaptability of living organisms, which called the principle of fluctuation-driven attractor selection is reviewed and the possibility of a material-based stochastic information processing system is discussed. Furthermore, stochastic resonance phenomenon in an organic field effect transistor is introduced and robustness of the Organic Field Effect Transistor (OFET) against external noise is shown, which is due to existence of internal noise in the OFET.
Keywords: Stochastic Resonance / Organic Semiconductor / Neural Network / Neuromorphic Device / Noise-Driven Signal Transmission / Organic Field Effect Transistor / Attractor Selection / Bifurcation
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Precise “Control” of Polymers Using DNA Akinori KUZUYA
<Abstract> DNA is a unique biopolymer, which has high programmability based on strict sequence recognition and quite uniform secondary structure, right-handed double helix. It is thus often used in molecular computing as well as in the construction of precise nanostructures. It is also an organic compound, whose chemical synthesis method has been well established. If such DNA is combined with polymers, it is possible to “control” their topology, higher-order structure, and even behavior at will. Recent typical achievements using DNA as “versatile molecular-manipulator for polymers,” targeting both synthetic polymers and biomacromolecules, are outlined.
Keywords: DNA / Cyclodextrin / Rotaxanes / Hydrogels / DNA Origami / Molecular Robots
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COVER STORY: Topics and Products
Neuromorphic Device Based on Mixed Conducting Polymer Materials Shunsuke YAMAMOTO
<Abstract> This article introduces the neuromorphic studies of organic electrochemical transistors (OECTs) based on polymer blends of a mixed conductor (PEDOT:PSS) and an ion conductor (PSSNa). The addition of an ionic conductor into PEDOT:PSS decreases information retention time in paired-pulse depression (PPD) experiments. Detailed studies of transient properties and modeling demonstrate that the relevant timescales for neuromorphic response are determined by the transient response of the ionic circuit of the OECT. These insights on device response pave the way for a rational design of OECT-based neuromorphic devices.
Keywords: Conjugated Polymer / Organic Electronics / Iontronics / Organic Electrochemical Transistors
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Nanopore Decoding for DNA Computing and Its Development for Diagnostic Applications Sotaro TAKIGUCHI, Ryuji KAWANO
<Abstract> DNA computing has attracted attention as a tool for implementing various mathematical models. However, decoding the output information to a human-recognizable signal generally requires time-consuming processes or fluorescence detection. To employ rapid and label-free decoding, nanopore technology, an emerging tool for single-molecule sensing, is proposed as a promising candidate for the electrical decoding of DNA computations. Nanopores can recognize and identify the individual molecules as an ionic current blockage, leading us to take advantage of the sequence-programmability of DNA. We here briefly review our recent results of nanopore decoding for mathematical DNA computing. In addition to such mathematical applications, DNA computing is expanding the research field to diagnostic applications due to the biocompatibility of DNA. As a real-life application of our proposed method, we here introduce our recent work on nanopore-based microRNA detection and DNA computing-assisted pattern recognition for cancer diagnosis. We believe that nanopore technology paves the way for the social implementation of DNA computing/storage technology.
Keywords: Nanopore / DNA Computing / Decoding / MicroRNA / Pattern Recognition / Diagnosis / Liquid Biopsy / Microfluidics
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Polymer Science and I: A Personal Account
Keep Tryin’ Fumitaka ISHIWARI
<Abstract> Scince my childhood, I have recognized that I was not as smart as others. In this paper, I briefly summarized how I have managed my life up to the present where I serve as a faculty of a university.
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Front-Line Polymer Science
Recent Development of Chemical Recycling Method for Polyethylene Terephthalate (PET) Shinji TANAKA
<Abstract> Polyethylene terephthalate (PET) resin is an abundant plastic utilized for beverage bottles, fibers, and films. The increasing social attentions on recycling of waste plastics has prompted rapid progress in chemical recycling methods for PET resin. In this article, the author summarized chemical recycling methods for PET resin developed in industry. In particular, recent techniques focused on low-energy processes using a catalytical approach as well as a biochemical approach were described. In addition, a dimethyl carbonate (DMC) using method, which involves utilization of DMC as trapping reagent of ethylene glycol, was highlighted. This DMC method allowed us to isolate dimethyl terephthalate in high yields from PET resin under mild reaction conditions (28~50℃).
Keywords: Chemical Recycle / Polyethylene Terephthalate / Catalysis / Transesterification / Depolymerization
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