Publications by authors named "Ryo Fukaya"

The photoinduced crawling motion of crystals is a continuous motion that azobenzene molecular crystals exhibit under light irradiation. Such motion enables object manipulation at the microscale with a simple setup of fixed LED light sources. Transportation of nano-/micromaterials using photoinduced crawling motion has recently been reported.

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Operando time-resolved soft x-ray absorption spectroscopy (TR-SXAS) is an effective method to reveal the photochemical processes of metal complexes in solutions. In this study, we have developed the TR-SXAS measurement system for observing various photochemical reactions in solutions by the combination of laser pump pulses with soft x-ray probe pulses from the synchrotron radiation. For the evaluation of the developed TR-SXAS system, we have measured nitrogen K-edge x-ray absorption spectroscopy (XAS) spectra of aqueous iron phenanthroline solutions during a photoinduced spin transition process.

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Article Synopsis
  • - A new measurement system for picosecond pump-probe resonant soft X-ray scattering has been developed at the Photon Factory to enhance data collection efficiency.
  • - A high-repetition-rate and high-power compact laser system is now in place, allowing for flexible data acquisition at sub-MHz frequencies for time-resolved experiments.
  • - The system successfully captures the photoinduced dynamics of magnetic order in multiferroic manganite SmMnO, showing changes in resonant soft X-ray scattering around the Mn L- and O K-edges.
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Interleukin 15 receptor (IL-15R) is a transmembrane signalling protein consisting of 3 subsets: α, β (IL-15Rβ), and γ (γ). IL-2 and IL-15 share the signalling domains IL-15Rβ and γ, although they bind to intrinsic α-subsets and non-signalling domains. Additionally, IL-2 and IL-15 play different roles; therefore, there have been many observations of the dynamic behaviours of IL-15R, which are linked to physiological functions.

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G protein-coupled receptors (GPCRs) are seven-transmembrane proteins, which transmit extracellular signals inside cells via activating G proteins. GPCRs are involved in a wide variety of physiological functions, such as signal sensing, immune system processes, and neurotransmission. Although the structures and functions of GPCRs have been well studied, little has been known about their real-time dynamics on live cells.

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Article Synopsis
  • Researchers studied the vibrational dynamics of a chemical reaction involving a gold trimer complex using advanced femtosecond X-ray techniques.
  • They successfully tracked how the bond between three molecules A, B, and C formed over time after photoexcitation, resulting in an A-B-C trimer.
  • This approach could potentially allow scientists to observe the movements of lighter atoms in chemical reactions, enhancing our understanding of various fundamental processes.
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The combination of high-power laser and synchrotron X-ray pulses allows us to observe material responses under shock compression and release states at the crystal structure on a nanosecond time scale. A higher-power Nd:glass laser system for laser shock experiments was installed as a shock driving source at the NW14A beamline of PF-AR, KEK, Japan. It had a maximum pulse energy of 16 J, a pulse duration of 12 ns and a flat-top intensity profile on the target position.

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A two-dimensional nanocarbon, graphene, has attracted substantial interest due to its excellent properties. The reduction of graphene oxide (GO) has been investigated for the mass production of graphene used in practical applications. Different reduction processes produce different properties in graphene, affecting the performance of the final materials or devices.

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Plastic deformation of polycrystalline materials under shock wave loading is a critical characteristic in material science and engineering. However, owing to the nanosecond time scale of the shock-induced deformation process, we currently have a poor mechanistic understanding of the structural changes from atomic scale to mesoscale. Here, we observed the dynamic grain refinement of polycrystalline aluminum foil under laser-driven shock wave loading using time-resolved X-ray diffraction.

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Understanding the excited state of photocatalysts is significant to improve their activity for water splitting reaction. X-ray absorption fine structure (XAFS) spectroscopy in X-ray free electron lasers (XFEL) is a powerful method to address dynamic changes in electronic states and structures of photocatalysts in the excited state in ultrafast short time scales. The ultrafast atomic-scale local structural change in photoexcited WO was observed by W L edge XAFS spectroscopy using an XFEL.

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Ultrafast excitation of photocatalytically active BiVO was characterized by femto- and picosecond transient X-ray absorption fine structure spectroscopy. An initial photoexcited state (≪500 fs) changed to a metastable state accompanied by a structural change with a time constant of ∼14 ps. The structural change might stabilize holes on oxygen atoms since the interaction between Bi and O increases.

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The dynamics of the local electronic and geometric structures of WO3 following photoexcitation were studied by femtosecond time-resolved X-ray absorption fine structure (XAFS) spectroscopy using an X-ray free electron laser (XFEL). We found that the electronic state was the first to change followed by the local structure, which was affected within 200 ps of photoexcitation.

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Resonant couplings of the electronic states and the stretching vibrations of CN(-) ligands, which bridges metal ions, is investigated by resonance Raman spectroscopy for Rb(0.94)Mn[Fe(CN)6](0.98)·0.

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A 78-year-old woman presented with fever, severe abdominal pain, and distension. She had been institutionalized for depression and senile dementia. Laboratory examinations disclosed a leucocytosis (WBC: 12,500/microL) and elevated levels of serum C-reactive protein (2.

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