248390 research outputs found
Sort by
Cell body area expansion is a key factor determining connectivity and diameter of on-chip vascular networks
No full textThis study aimed to identify the key determinants of vascular networks (VN) morphology, with a particular focus on the role of endothelial cell body area expansion. We introduced a quantitative metric, the cell body area expansion (CBE) score, to assess endothelial cell (EC) enlargement during the early stage of self-organizing vascular network formation. The CBE score positively correlated with both VN connectivity and vessel diameter. Notably, VNs formed in the absence of growth factors exhibited reduced connectivity accompanied by lower CBE scores, while protrusion formation remained unaffected. Additionally, comparative analysis of multiple EC types revealed that cells forming wider vascular branches consistently showed higher CBE score. A mathematical model further supported these findings, demonstrating that greater CBE leads to VNs with enhanced connectivity and larger branch diameters
Structure and function of the RNA polymerase complex of Borna disease virus, a nuclear-replicating non-segmented negative-strand RNA virus
No full textBorna disease virus 1 (BoDV-1) is a non-segmented negative-strand (NNS) RNA virus that uniquely replicates in the nucleus of mammalian host cells, in contrast to most NNS RNA viruses that replicate in the cytoplasm. The mechanisms underlying nuclear replication of BoDV-1 and related bornaviruses with their RNA-dependent RNA polymerase (RdRp) complexes remain poorly understood. Here, we report the 2.8 Å cryo-EM structure of the BoDV-1 RdRp complex, comprising the large (L) protein and tetrameric phosphoprotein (P). The L protein features an N-terminal superdomain containing the RdRp and GDP polyribonucleotidyltransferase (PRNTase, mRNA-capping enzyme) domains, along with three C-terminal appendages, including a methyltransferase-like domain. The RdRp initiates de novo RNA synthesis internally at the genomic promoter, producing 5′-triphosphorylated transcripts corresponding to the 5′ end of the anti-genome. P interacts with the fingers RdRp subdomain of L. Structure-guided mutagenesis shows that the residues involved in the L–P interaction are essential for efficient transcription initiation and, consequently, for viral gene expression. A flexible loop within the PRNTase domain, analogous to the rhabdovirus priming-capping loop, appears critical for transcription initiation. These findings provide the structural and functional insights into the BoDV-1 RdRp and support a shared evolutionary origin between nuclear and cytoplasmic NNS RNA viruses
Cholesterol-Based Molecular Glasses: Attempts to Control Their Thermal Stability and Mechanical Properties
No full textDriven by environmental concerns regarding conventional polymer-based materials, biomolecule-derived bulk solids, such as glasses and plastics, are attracting increasing attention. Here, we report molecular glasses consisting of a hydrophobic cholesterol scaffold. By designing intermolecular hydrogen bonding, crystallization was suppressed; however, the glassy state was kinetically unstable. We explored a simple strategy of mixing two cholesterol derivatives in the expectation that this would produce a greater diversity in intermolecular interactions and thereby enhance the glass-forming ability. Gratifyingly, we obtained stable, humidity-resistant, transparent glasses with tunable mechanical properties in a scalable manner. The optimized glass exhibited a hardness of H = 88 MPa and a reduced modulus of E[r] = 3.1 GPa (nanoindentation analysis), values comparable to those of known molecular glasses and approaching those of conventional polycarbonate glass. This study highlights a promising strategy for developing sustainable hydrophobic organic glassy materials
Programmable fracture toughness in architected mechanical metamaterials
No full textArchitected mechanical metamaterials - engineered materials whose mechanical behavior primarily arises from the structure - have recently enabled on-demand tuning of stiffness, Poisson's ratio, and mechanical wave propagation properties. However, the programmable control of fracture toughness - a key material property governing fracture resistance - has been investigated, but its potential has yet to be fully explored. In particular, no existing metamaterial has achieved this control without altering its structural topology and deformation stiffness along the loading direction. Here, we present a two-dimensional spring-lattice metamaterial that enables programming of fracture toughness decoupling it from deformation stiffness through orthogonal stiffness modulation. By varying the stiffness ratio between vertical and lateral springs (α), the load transfer near the crack tip was independently tuned while maintaining the vertical deformation stiffness identical. Pre-cracked specimens with different α values were subjected to tensile test experiments and finite-element analysis. Despite identical deformation stiffness, the energy release rate at crack propagation (fracture toughness) considerably varied with α across specimens. These results demonstrated that fracture toughness could be programmed purely via structural stiffness design. Furthermore, this concept was shown to be extendable to three-dimensional architectures. This finding introduces a new design axis in architected materials and suggests a route toward mechanically robust, tunable systems for structural reliability
In-orbit demonstration of X-ray pulsar navigation with NinjaSat
No full text地球との通信に依存しない自律的な宇宙航法へ一歩 --超小型X線衛星NinjaSatによるX線パルサー航法の実証--. 京都大学プレスリリース. 2026-03-04.We demonstrate the pulsar navigation capability of a CubeSat X-ray observatory, NinjaSat, equipped with two sets of gas multiplier counters (GMCs). GMCs are sensitive to the 2 to 50 keV band with an effective area of 16 cm² per module at 6 keV. We verified the timing accuracy by observing Crab Pulsar and confirmed that a stable timing measurement performance is stable within 100μs. To demonstrate the pulsar navigation, we applied a method that optimizes orbital parameters to maximize the significance of the pulse profile of X-rays from a pulsar using “Significance Enhancement of Pulse-profile with Orbit-dynamics (SEPO).” We observed Crab Pulsar with an exposure time of ∼ 100 ks at different epochs and analyzed the data downlinked to the ground. By comparing the optimized orbit with the satellite position derived from Global Positioning System data, we quantitatively evaluated the pulsar navigation performance. The results showed that the position component along the Crab line of sight was consistently constrained within ∼ 40 km, and the range of three-dimensional error varied between 27 and 370 km depending on the observation epoch. We demonstrate the feasibility of applying a CubeSat-class X-ray observatory to pulsar navigation and also provide the first experimental verification that the accuracy of the SEPO method depends on the seasonal geometry between the orbital plane and the pulsar direction
Triplet nitrene-mediated photocatalytic azidation of tertiary C(sp³)–H bonds
No full textA photocatalytic C(sp³)–H azidation involving a triplet nitrene as a hydrogen atom abstractor is described. The key nitrene intermediate is generated through energy transfer to a sulfonyl azide, which also functions as an azide source. This method exhibits excellent selectivity for tertiary C–H bonds and is applicable to leucine-containing dipeptides
ラット廃用性筋萎縮モデルに対する肝切除における周術期HMB経口投与はサルコペニアを改善する
No full text京都大学新制・論文博士博士(医学)乙第13733号論医博第2370号京都大学大学院医学研究科医学専攻(主査)教授 妹尾 浩, 教授 池口 良輔, 教授 西谷 陽子学位規則第4条第2項該当Doctor of Medical ScienceKyoto UniversityDFA
Case report of bacteremia, with genomic characterization of its clinical isolate
No full text: was initially isolated from food in Thailand, and a single clinical case involving an intra-abdominal abscess was reported. No reports on the bacteremia or whole-genome sequencing of clinically isolated . have been published. : A 50-year-old woman with intestinal Crohn's disease was admitted because of bloody stools. She had been treated twice previously for a perianal abscess. She developed a fever on day 15 of hospitalization. Both blood and urine cultures were polymicrobial and included . , which was susceptible to penicillins. She was treated for the perianal abscess and pyelonephritis with intravenous penicillins combined with beta-lactamase inhibitors for 2 weeks, followed by oral amoxicillin-clavulanic acid for 4 weeks. The identities of the isolates in the blood and urine cultures were confirmed using whole-genome analysis. No antimicrobial resistance genes, virulence genes, or plasmid replicons were identified in these isolates. Phylogenetic analysis of the clinical isolates and 21 . isolates in public databases indicated a relatively close lineage to that obtained from pig stool samples in Japan. No antimicrobial resistance genes conferring resistance to penicillins were identified in any of the . genomes. : Phylogenetic analysis suggested that infection with . in this patient may have originated in Japan. The prognosis after treatment with penicillins was favorable
