Publications by authors named "Daisuke Kawaguchi"

Background: Assessing lower limb ranges of motion (ROMs) is crucial for diagnosing and treating musculoskeletal and neurological disorders in children. Although prior studies examining decline in flexibility among school-age children suggest potential age-related changes in lower limb ROMs, this hypothesis remains unproven. Therefore, in this study, we aim to examine age-related differences in lower limb ROMs among school-age children.

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We developed phosphorylation reagents with a nitrobenzyl hydrophobic tag and used them for 5'-phosphorylation of chemically or transcriptionally synthesized RNA. The capability of hydrophobic tags to synthesize 5'-monophosphorylated RNA was evaluated based on the yield of the desired oligonucleotides, stability of protecting groups during cleavage/deprotection, separation ability in reverse-phase HPLC (RP-HPLC), and deprotection efficiency after RP-HPLC purification. The results showed that a nitrobenzyl derivative with a tert-butyl group at the benzyl position was most suitable for RNA 5'-phosphorylation.

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Article Synopsis
  • Utilizing fluorine substitution can enhance the properties of materials, leading to the development of highly functional copolymers.
  • A novel copolymer was created from [1.1.1]propellane and perfluoro(propyl vinyl ether) (PPVE) with distinct alternating sequences, forming an amorphous spin-coated film.
  • The copolymer film demonstrated an extremely low surface free energy, even lower than that of polytetrafluoroethylene, due to the random orientation of the fluorine units cancelling out C-F dipole moments.
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Individuals with bilateral spastic cerebral palsy (BSCP) reportedly has problems with anticipatory postural adjustments (APAs) while standing. However, the use of coactivation strategy in APAs in individuals with BSCP has conflicting evidence. Hence, this study aimed to investigate postural muscle activities in BSCP during unilateral arm flexion task in which postural perturbations occur in the sagittal, frontal, and horizontal planes.

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Purpose: To determine whether foot and ankle functions are correlated with the limits of stability (LoS) while standing in individuals with bilateral spastic cerebral palsy (BSCP).

Methods: Eighteen people who could walk and with BSCP and 18 people without disability participated. Anteroposterior LoS was measured using a force platform.

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Forming nano-assemblies is essential for delivering DNA conjugates into cells, with the DNA density in the nano-assembly playing an important role in determining the uptake efficiency. In this study, we developed a strategy for the facile synthesis of DNA strands bearing perfluoroalkyl (R) groups (R-DNA conjugates) and investigated how they affect cellular uptake. An R-DNA conjugate bearing a long R group at the DNA terminus forms a nano-assembly with a high DNA density, which results in greatly enhanced cellular uptake.

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A better understanding of the aggregation states of adhesive molecules in the interfacial region with an adherend is crucial for controlling the adhesion strength and is of great inherent academic interest. The adhesion mechanism has been described through four theories: adsorption, mechanical, diffusion, and electronic. While interfacial characterization techniques have been developed to validate the aforementioned theories, that related to the electronic theory has not yet been thoroughly studied.

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Article Synopsis
  • Upper limb movement is essential for daily activities, and a biomechanical simulation of the forearm helps us understand its mechanics better.
  • The study created a detailed finite element model of the forearm to simulate the motion caused by biceps brachii contraction and found that slower contraction speeds improved forearm flexion.
  • The research also showed that older adults experience reduced forearm motion due to decreased fast-twitch fiber percentage, max muscle strength, and neural activation, helping identify potential targets for improving upper limb function.
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Polymer chains at a buried interface with an inorganic solid play a critical role in the performance of polymer nanocomposites and adhesives. Sum frequency generation (SFG) vibrational spectroscopy with a sub-nanometer depth resolution provides valuable information regarding the orientation angle of functional groups at interfaces. However, in the case of conventional SFG, since the signal intensity is proportional to the square of the second-order nonlinear optical susceptibility and thereby loses phase information, it cannot be unambiguously determined whether the functional groups face upward or downward.

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  • The study introduces a method to improve the ionic conductivity of block copolymer electrolytes by using mixed ionic liquids (ILs) with different ratios of cations and anions.
  • Two polymer types, SSMB and STMB, were developed, and their structures were affected by the type of acid group used, impacting their ionic properties.
  • The SSMB electrolytes showed better ionic conductivity than expected due to effective ion distribution, while STMB's conductivity matched expectations, indicating potential for future solid-state electrolyte development.
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  • - Water absorbed by epoxy resins from humid environments significantly impacts their structure and properties, especially in adhesive applications.
  • - A study using neutron reflectometry revealed a 1-nm-thick condensed water layer forms at the SiO/epoxy resin interface after 8 hours at 85% humidity, influenced by curing conditions.
  • - The findings suggest that high-temperature and high-humidity conditions can alter water accumulation at the interface, highlighting the importance of improving epoxy resin construction to reduce this issue in practical use.
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Starting with the clinical application of two vaccines in 2020, mRNA therapeutics are currently being investigated for a variety of applications. Removing immunogenic uncapped mRNA from transcribed mRNA is critical in mRNA research and clinical applications. Commonly used capping methods provide maximum capping efficiency of around 80-90% for widely used Cap-0- and Cap-1-type mRNAs.

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Article Synopsis
  • - The study explored anticipatory postural adjustments (APAs) and compensatory postural adjustments (CPAs) in adolescents and young adults with bilateral spastic cerebral palsy (BSCP), revealing APAs were deficient during voluntary movement while standing.
  • - Participants included two groups with different severity levels of BSCP and healthy controls; muscle activity was recorded while lifting loads of varying weights on a force platform.
  • - Results showed BSCP participants relied more on CPAs compared to controls, especially in those with milder BSCP, indicating that severity of the condition affects the modulation of both APAs and CPAs during movement.
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A better understanding of the chemical reaction between epoxy and amine compounds at a solid interface is crucial for the design and fabrication of materials with appropriate adhesive strength. Here, we examined the curing reaction kinetics of epoxy phenol novolac and 4,4'-diaminodiphenyl sulfone at the outermost interface using sum-frequency generation spectroscopy, and X-ray and neutron reflectivity in conjunction with a full atomistic molecular dynamics simulation. The reaction rate constant was much larger at the quartz interface than in the bulk.

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Site-specific chemical modification of mRNA can improve its translational efficiency and stability. For this purpose, it is desirable to develop a complete chemical synthesis method for chemically modified mRNA. The key is a chemical reaction that introduces a cap structure into the chemically synthesized RNA.

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The interfacial strength of polystyrene (PS) with and without PS oligomers in contact with a glass substrate was examined to determine the relationship between the interfacial aggregation state and adhesion. The shear bond strength and adsorbed layer thickness of neat PS exhibited a similar dependence on the thermal annealing time: they increased to constant values within almost the same time. This implies that the adhesion of the polymer is closely related to the formation of an adsorbed layer at the adhesion interface.

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Due to the importance of the interface in the segmental dynamics of supported macromolecule ultrathin films, the glass transition temperature () of polystyrene (PS) ultrathin films upon solid substrates modified with a cross-linked PS (CLPS) layer has been investigated. The results showed that the of the thin PS films on a silica surface with a ∼5 nm cross-linked layer increased with reducing film thickness. Meanwhile, the increase in of the thin PS films became more pronounced with increasing the cross-linking density of the layer.

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Article Synopsis
  • The study presents a new laser slicing technique for GaN substrates, which are expensive and often wasteful when cut using traditional methods.
  • The researchers explored this technique's effectiveness in fabricating high-electron-mobility transistors (HEMTs), demonstrating that HEMTs remain intact and function well even after being thinned down to 50 mm.
  • This discovery indicates that the laser slicing method can be utilized post-fabrication, enabling the production of ultra-thin semiconductor devices with minimal substrate waste.
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Adhesion is a molecular event where polymer chains contact with a material surface to form an interfacial layer. To obtain a better understanding of the adhesion on a molecular scale, we herein examined the conformational change of polystyrene (PS) chains at the film surface after contacting with hydrophobic or hydrophilic surfaces using sum-frequency generation (SFG) spectroscopy. Chains altered their local conformations with a quartz surface more quickly than a hydrophobic alkyl-functionalized one.

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  • The study investigates how the adsorbed layer on solid surfaces affects the dynamics of confined polymer materials, specifically thin films of polystyrene (PS).
  • Results indicate that thicker adsorbed layers and higher molecular weight PS lead to significantly suppressed segmental dynamics in the thin films.
  • The research shows that the distance over which the adsorbed layer influences these dynamics is linked to the overlapping region between the adsorbed layer and the thin film, with larger polymer structures enhancing interpenetration and entanglement.
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The mechanical properties in the outermost region of a polymer film strongly affect various material functions. We here propose a novel and promising strategy for the two-dimensional regulation of the mechanical properties of a polymer film at the water interface based on an inkjet drawing of silica nanoparticles (SNPs) underneath it. A film of poly(2-hydroxyethyl methacrylate) (PHEMA), which exhibits excellent bioinertness properties at the water interface, was well fabricated on a substrate with a pattern of SNPs.

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  • - A deep understanding of how polymer chains arrange in thin films is crucial for both the development of polymer devices and for research purposes.
  • - This study focuses on isotactic polypropylene (iPP) and uses advanced techniques like X-ray diffraction and vibrational spectroscopy to analyze the orientation of crystalline structures within the films.
  • - As the thickness of the iPP films decreases, the orientation of crystalline lamellae shifts from a mix of edge-on and face-on arrangements to predominantly face-on, which also affects the orientation of methyl groups at the crystal/amorphous interfaces.
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We have investigated the possibility of applying lasers to slice GaN substrates. Using a sub-nanosecond laser with a wavelength of 532 nm, we succeeded in slicing GaN substrates. In the laser slicing method used in this study, there was almost no kerf loss, and the thickness of the layer damaged by laser slicing was about 40 µm.

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