Hiroyuki Oikawa
A5090822902- Nuclear physics research studies
- Nuclear Physics and Applications
- Advanced Fluorescence Microscopy Techniques
- Photosynthetic Processes and Mechanisms
- Biotin and Related Studies
- Protein Structure and Dynamics
- Semiconductor materials and devices
- Astronomical and nuclear sciences
- Spectroscopy and Quantum Chemical Studies
- 14-3-3 protein interactions
- Particle physics theoretical and experimental studies
- Advanced Biosensing Techniques and Applications
- Quantum Chromodynamics and Particle Interactions
- Radiation Detection and Scintillator Technologies
- Enzyme Structure and Function
- Analytical Chemistry and Sensors
- Monoclonal and Polyclonal Antibodies Research
- Ubiquitin and proteasome pathways
- Particle Detector Development and Performance
- Mechanical and Optical Resonators
- Nuclear reactor physics and engineering
- Advanced Electron Microscopy Techniques and Applications
- Advanced biosensing and bioanalysis techniques
- Astro and Planetary Science
- Semiconductor materials and interfaces
Tokyo University of Science
2016-2025
Tohoku University
2012-2023
RIKEN Nishina Center
2022
VNU University of Science
2022
Tokyo City University
2019
Tokyo Institute of Technology
2008-2011
National Agriculture and Food Research Organization
2010
Centre de Recherche en Économie et Statistique
2009
Centre for Research in Engineering Surface Technology
2009
Nagoya Institute of Technology
2008
We perform the first direct mass measurements of neutron-rich calcium isotopes beyond neutron number 34 at RIKEN Radioactive Isotope Beam Factory by using time-of-flight magnetic-rigidity technique. The atomic excesses ^{55-57}Ca are determined for time to be -18650(160), -13510(250), and -7370(990) keV, respectively. examine emergence magicity N=34 based on new masses. masses provide experimental evidence appearance a sizable energy gap between 2p_{1/2} 1f_{5/2} orbitals in ^{54}Ca,...
In an experiment with the BigRIPS separator at RIKEN Nishina Center, we observed two-proton (2p) emission from ^{67}Kr. At same time, no evidence for 2p of ^{59}Ge and ^{63}Se, two other potential candidates this exotic radioactivity, could be observed. This observation is in line Q value predictions which pointed to ^{67}Kr as being best new candidate among three radioactivity. only fourth ground-state emitter a half-life order few milliseconds. The decay energy was determined 1690(17) keV,...
We performed the first direct mass measurements of neutron-rich scandium, titanium, and vanadium isotopes around neutron number 40 at RIKEN RI Beam Factory using time-of-flight magnetic-rigidity technique. The atomic excesses Sc58−60, Ti60−62, V62−64 were measured for time. experimental results show that two-neutron separation energies in vicinity Ti62 increase compared to neighboring nuclei. This shows masses Ti near N=40 are affected by Jahn-Teller effect. Therefore, a development...
We present a new method for high speed tracking of fluorescence time series from single proteins. The uses fast sample flow and modified confocal microscopy, line microscopy achieves the resolution less than 20 μs. obtained B domain protein A labeled with donor acceptor fluorophores suggest conformational heterogeneity dynamic fluctuations in unfolded state.
In an experiment with the RIKEN projectile fragment separator called BigRIPS at Nishina Center, fragmentation of a $^{78}\mathrm{Kr}$ beam allowed observation new neutron-deficient isotopes proton drip line. Clean identification spectra could be produced and $^{63}\mathrm{Se},\phantom{\rule{0.16em}{0ex}}^{67}\mathrm{Kr}$, $^{68}\mathrm{Kr}$ were identified for first time. addition, $^{59}\mathrm{Ge}$ was also observed. Three these isotopes,...
The nucleocapsid (N) protein of SARS-CoV-2 associates with the viral genomic RNA (gRNA) and forms ribonucleoprotein (RNP) granules. However, detailed molecular structures RNP their formation mechanism are largely unknown. We used circular dichroism (CD) spectroscopy, fluorescence correlation spectroscopy (FCS) single-molecule Forster resonance energy transfer (sm-FRET) to understand interaction between N different structural units RNA. chose polyadenylate chains 40, 30 20 bases possessing a...
Isospin symmetry is a fundamental concept in nuclear physics. Even though isospin partially broken, it holds approximately for most systems, which makes exceptions very interesting from the structure perspective. In this framework, expected that spins and parities of ground states mirror nuclei should be same, particular simplest systems where proton exchanged with neutron or vice versa. Letter, we present evidence assumption broken pair ^{71}Br ^{71}Kr system. Our conclusions are based on...
Key techniques for applying Ta/sub 2/O/sub 5/ film to megabit-class MOS DRAMs are presented. A high-purity (4N and up) Ta sputtering target is developed obtain film. The leakage current in that deposited using a clean system with this far lower than of conventional target. previous drawback 5/, the decrease effective dielectric constant as thickness decreases, solved by Mo an electrode material. increase results from metal bottom suppressed reducing asperity. up 16-Mb capacity can be...
Elucidating the protein folding mechanism is crucial to understand how proteins acquire their unique structures realize various biological functions. With this aim, folding/unfolding of small globular has been extensively studied. Interestingly, recent studies have revealed that even such represent considerably complex processes. In study, we examined process a α-helical protein, B domain A (BdpA), at equilibrium using two-dimensional fluorescence lifetime correlation spectroscopy with 10 μs...
Abstract Despite the continuous discovery of host and guest proteins in membraneless organelles, complex host–guest interactions hinder understanding molecular grammar governing liquid–liquid phase separation. In this study, we characterized localization dynamic properties liquid droplets using single-molecule fluorescence microscopy. Eighteen different sizes, structures, oligomeric states were examined p53 droplets. Recruitment did not significantly depend on structural proteins, but was...
The fluorescence excitation spectrum of a single chromophore molecule in photosynthetic pigment−protein complex is known to change time at liquid helium temperature. spectral reflects conformational the protein which binds. This work follows temporal behavior temperature range between 5 adn 18 K. dependence reveals two types protein, i.e., thermally activated motions over potential barrier ca. 0.1 kJ/mol and temperature-independent tunneling proton.
The $\ensuremath{\beta}$ decay of the odd-odd nucleus $^{70}\mathrm{Br}$ has been investigated with BigRIPS and EURICA setups at Radioactive Ion Beam Factory (RIBF) RIKEN Nishina Center. $T=0({J}^{\ensuremath{\pi}}={9}^{+})$ $T=1({J}^{\ensuremath{\pi}}={0}^{+})$ isomers have both produced in in-flight fragmentation $^{78}\mathrm{Kr}$ ratios 41.6(8)% 58.4(8)%, respectively. A half-life ${t}_{1/2}={2157}_{\ensuremath{-}49}^{+53}$ ms measured for ${J}^{\ensuremath{\pi}}={9}^{+}$ isomer from...
The equilibrium unfolding transition of the B domain protein A (BdpA) was investigated by using single-molecule fluorescence spectroscopy based on line-confocal detection fast-flowing samples. method achieved time resolution 120 μs and observation a few milliseconds in time-series measurements resonance energy transfer (FRET). Two samples BdpA doubly labeled with donor acceptor fluorophores, first possessing fluorophores at residues 22 55 (sample 1) second 5 2), were prepared. induced...
RNA in extracellular vesicles (EVs) are uptaken by cells, where they regulate fundamental cellular functions. EV-derived mRNA recipient cells can be translated. However, it is still elusive whether "naked nonvesicular mRNA" (nex-mRNA) that not packed EVs and, if so, have any functions cells. Here, we show the entrance of nex-mRNA nucleus, exert a translation-independent function. Human nex-interleukin-1β (IL1β)-mRNA outside proved to captured RNA-binding zinc finger CCCH domain containing...
We report here the results of a study $\beta$ decay proton-rich Ge isotopes, $^{60}$Ge and $^{62}$Ge, produced in an experiment at RIKEN Nishina Center. have improved our knowledge half-lives $^{62}$Ge (73.5(1) ms), (25.0(3) ms) its daughter nucleus, $^{60}$Ga (69.4(2) ms). measured individual $\beta$-delayed proton $\gamma$ emissions their related branching ratios. Decay schemes absolute Fermi Gamow-Teller transition strengths been determined. The mass excesses nuclei under deduced. A total...
As a model of photosynthetic unit (PSU), self-assembled aggregates pigment-protein complexes from bacteria were prepared in lipid bilayer by reconstitution the light-harvesting 2 (LH2) complex and 1-reaction center (LH1-RC) through detergent removal their micelles presence lipids. By performing polarization-controlled fluorescence fluorescence-excitation spectroscopy on single at temperature 5 K, composition individual was determined excitation energy transfer (EET) between constituent...
The conformation and dynamics of the unfolded state ubiquitin doubly labeled regiospecifically with Alexa488 Alexa647 were investigated using single-molecule fluorescence spectroscopy. line confocal detection system combined rapid sample flow enabled characterization proteins at improved structural temporal resolutions compared to conventional methods. In initial stage current investigation, however, Förster resonance energy transfer (sm-FRET) data flawed by artifacts caused adsorption...
The β-decay of the even-even nucleus 70Kr with Z=N+2, has been investigated at Radioactive Ion Beam Factory (RIBF) RIKEN Nishina Center using BigRIPS fragment separator, ZeroDegree Spectrometer, WAS3ABI implantation station and EURICA HPGe cluster array. Fifteen γ-rays associated into 70Br have identified for first time, defining ten populated states below Eexc=3300 keV. half-life was derived increased precision found to be t1/2=45.19±0.14 ms. β-delayed proton emission probability also...
Single-molecule (sm) fluorescence time series measurements based on the line confocal optical system are a powerful strategy for investigation of structure, dynamics, and heterogeneity biological macromolecules. This method enables detection more than several thousands photons per millisecond from single fluorophores, implying that potential resolution resonance energy transfer (FRET) efficiency is 10 μs. However, necessity using imaging photodetectors in limits FRET to approximately 100 In...
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We investigate the conformational properties of intrinsically disordered DNA-binding domain CytR in presence polymeric crowder polyethylene glycol (PEG). Integrating circular dichroism, nuclear magnetic resonance, and single-molecule Förster resonance energy transfer measurements, we demonstrate that populates a well-folded minor conformation its native ensemble, while unfolded ensemble collapses folds with an increase density independent size. Employing statistical-mechanical model,...