Tokyo University of Science

Ceramic Matrix Composites (CMCs) are materials in which ceramics are reinforced with fibers or other materials, providing enhanced functionalities, such as damage tolerance, in addition to their inherent heat resistance. This study investigates a manufacturing method for continuous alumina-mullite fiber-reinforced alumina CMCs using a commercial Fused Deposition Modeling (FDM) 3D printer, demonstrating a flexible and practical route for continuous fiber-reinforced CMC fabrication. The process utilizes a pre-impregnated filament, which serves as the fundamental component for depositing both the ceramic matrix and continuous reinforcement. The 3D printing filament was fabricated by melting a mixture of alumina, serving as the matrix material, and a thermoplastic resin to impregnate the alumina-mullite mixed fibers. Filaments with a diameter of 0.4 mm exhibited fewer cracks compared to those with a diameter of 0.6 mm. Moreover, a filament with fewer voids was produced when the heating temperature during impregnation was 230 °C. Using the fabricated filament, simple three-layered rectangular test specimens, with a length of 110 mm and a width of 10 mm, were successfully printed. A tensile strength of approximately 250 MPa was achieved along the fiber direction. The observed fracture behavior indicates that improving the interlaminar strength would likely further enhance the tensile strength. The impact of this research is introducing a new manufacturing method that will expand the design freedom and accessibility of complex-shaped CMCs. This pioneering achievement provides a foundational baseline for researchers and engineers to transition 3D printed continuous fiber-reinforced CMCs from laboratory-scale prototypes to structural components.

We propose interpolation-based algorithms that enable convolutional and transposed convolutional layers to operate with arbitrary (including non-integer) strides. A primary motivation for the proposed algorithms is to maintain a consistent temporal resolution when adapting deep neural networks (DNNs) to different sampling frequencies (SFs). To handle untrained SFs, we previously introduced SF-independent (SFI) convolutional layers, which adjust kernel weights in accordance with the target SF. However, achieving full consistency across SFs also requires the proportional adjustment of the stride, which results in non-integer values in many practical cases. Conventional algorithms for convolutional layers cannot handle such strides directly, and commonly used approaches (e.g., stride rounding or signal resampling) lead to performance degradation. To solve this problem, we propose a feature-domain interpolation framework that constructs continuous-time representations of intermediate features. This enables sampling at arbitrary stride intervals without modifying the network architecture. Through music source separation experiments, we show that the proposed algorithms maintain a strong performance across a range of SFs, including those where the stride becomes non-integer. Our analysis reveals that the proposed algorithms are robust to the choice of interpolation method and are especially effective for sources containing pitched sounds.

The first step in contemporary protein synthesis is the activation of amino acids by aminoacyl-tRNA synthetases, which form aminoacyl adenylates from ATP and amino acids. Previously, an RNA called KK13 was shown to catalyze amino acid activation by forming a bond between an amino acid and the α-phosphate of the 5'-triphosphate of its own RNA, analogous to the bond formed in aminoacyl adenylates. In the present study, we describe a putative novel RNA with catalytic activity, identified among previously uncharacterized sequences. The RNA, KK33-1 (114 nucleotides), exhibited activity comparable to that of a previously characterized ribozyme, KK13, as judged by a malachite green assay detecting pyrophosphate released from the 5'-triphosphate of the RNA. Guided by predicted secondary structure, truncation experiments indicated that certain smaller variants of KK33-1 can retain amino acid activation activity. Although attention was drawn to a CAAC sequence common to KK13 and KK33-1, which was positioned near the putative reaction site according to tertiary structure prediction, a mutational analysis revealed that this motif is not essential for catalysis. Together, the behaviors of KK33-1 and its mutants provide insights into the structural features supporting amino acid activation, refining our understanding of the ribozyme's functional architecture.

Poly(ADP-ribose) glycohydrolase (PARG) is a key enzyme involved in poly(ADP-ribose) (PAR) degradation and is considered a potential anticancer target. We previously investigated resistance mechanisms to the PARG inhibitor PDD00017273 in human colorectal cancer HCT116 cells and established an acquired PDD00017273-resistant HCT116RPDD cell line. In this study, we analyzed the protein levels of enzymes associated with PAR metabolism in both parental HCT116 cells and resistant HCT116RPDD cells using western blotting. PARG expression levels were similar between HCT116RPDD and HCT116 cells. However, the levels of PARP1 and ARH3 were reduced in HCT116RPDD cells compared to HCT116 cells. Nevertheless, intracellular PAR levels were elevated in HCT116RPDD cells. Interestingly, HCT116RPDD cells exhibited greater sensitivity to γ-ray irradiation and the nicotinamide phosphoribosyltransferase (NAMPT) inhibitor FK866 than the parental HCT116 cells, yet showed comparable sensitivity to 5-FU, cisplatin, and PARP inhibitors olaparib, talazoparib, and veliparib. Furthermore, we observed that HCT116RPDD cells tended to maintain slightly higher levels of intracellular NAD+/NADH and ATP compared to parental HCT116 cells. These findings suggest that cancer cells employ a mechanism to regulate NAD+ and ATP levels, thereby avoiding cell death from intracellular PAR accumulation through coordinated PARP-PARG regulation.

• Phase diagrams of CO 2 /EtOH/PEG and CO 2 /DMSO/PEG were systematically measured. • Cosolvent species strongly influenced ternary liquid–liquid phase separation. • Free volume fraction explained cosolvent effects on Px phase boundaries. • Dipole and quadrupole moments clarified mutual solubility among components. • Findings advance prediction of CO 2 /cosolvent/polymer phase behavior. Phase diagrams of CO 2 /cosolvent/polymer systems are critical for polymer processing applications, yet most studies have focused on pressure–temperature diagrams, leaving pressure–composition ( Px ) diagrams less understood. In particular, the influence of cosolvent species on ternary Px phase behavior and its molecular-level origin has not been systematically investigated. This study examined the phase behavior of CO 2 /ethanol (EtOH) or dimethyl sulfoxide (DMSO)/poly(ethylene glycol) (PEG) ternary systems to evaluate the effect of cosolvent species on the phase diagram. Measurements were performed using a synthetic method combined with laser displacement and turbidity detection. Bubble points (vapor–liquid (VL) phase separation) were determined from piston displacement changes, and cloud points (liquid–liquid (LL) phase separation) were identified from turbidity variations. Phase boundaries were obtained for CO 2 mass fractions of 0.148–0.680 while varying the cosolvent/PEG mass ratio. The polymer did not participate in VL phase separation, reflecting the affinity between CO 2 and the cosolvent. By contrast, LL phase separation required consideration of the mutual affinities among all three components. To support this interpretation, the free volume fraction difference ( Δf ) estimated from the Sanchez–Lacombe equation and the dipole and quadrupole moments obtained from quantum chemical calculations were analyzed. The Δf values explained the cosolvent-dependent shifts in the LL line, whereas the μ and Q values clarified the order of mutual solubility (EtOH > DMSO > Tol) in agreement with experimental observations. These findings provide a more comprehensive understanding of the CO 2 /cosolvent/polymer phase behavior and facilitate the prediction of phase diagrams.

Catalyst supports are indispensable for efficient water dissociation since they play key roles in either indirectly enhancing catalysis activity by modifying electronic structures of catalysts or directly participating in catalytic reaction. MXene has recently emerged as a promising catalyst support for water dissociation by virtue of its rich surface electronic states that enable various electronic modifications of catalysts, but its potential of directly interacting with reactants or products to accelerate catalytic dynamics in water dissociation remains unexplored. Here we report our finding that phosphate anion-engineered MXene is capable of significantly accelerating water dissociation on single-atom ruthenium-copper (Ru-Cu) alloy, achieving a record-high mass-specific activity of 746 L gRu -1 min-1 under light conditions at room temperature. This is mainly enabled by the accelerated hydrogen spillover effect, which results from the phosphate anion-induced electronic modification of titanium sites on MXene following the light-enhanced activation of ammonia borane and water molecules on Ru-Cu active sites. This underlying mechanism is elucidated by a combination of in situ spectroscopic characterizations and density function theory calculations. This work unveils a previously unrecognized catalytic role of MXene-based supports and offers a new design strategy for enhancing water dissociation through tailored support-catalyst-reactant interactions.

Entamoeba histolytica causes amoebiasis and damages intestinal epithelium, but how individual parasite factors coordinate parasite gene regulation with host remodeling is unclear. We investigate lysine- and glutamic acid-rich protein 2, a factor linked to the host brush border. Sequence analysis, imaging, and functional assays show that lysine- and glutamic acid-rich protein 2 accumulates in the parasite nucleus, binds AT-rich DNA, and modulates transcriptional programs related to Amoebiasis, including cysteine protease and sulfur metabolism. During parasite-epithelium contact, the protein enters host epithelial cells and is associated with increased deoxyribonucleic acid synthesis, altered cytoskeletal regulators, actin remodeling, and reduced barrier integrity. Here, we propose a working model in which lysine- and glutamic acid-rich protein 2 links parasite chromatin-associated regulation with host epithelial remodeling during contact. Notably, our data support host cytoskeletal and junctional phenotypes and do not yet establish a direct role for it in host chromatin regulation. Together, these observations suggest a potentially broader mechanism by which extracellular pathogens deploy effectors to optimize virulence and adapt to diverse host environments.

Microbial cutinases are promising biocatalysts for polymer recycling. Here, we investigated the structural basis of catalytic activation in a thermophilic cutinase from Chaetomium thermophilum (CtCut). Differential scanning calorimetry revealed a three-state thermal unfolding pathway (Tm = 66.4 °C and 69.5 °C), indicating hierarchical stability. To capture distinct conformational states while avoiding affinity-tag artifacts, we employed both tag-free and tagged constructs. We determined apo-structures of wild-type and S136A mutant CtCut at 1.7 Å resolution and a complementary inhibitor complex at 2.65 Å. In the apo-state, a chloride ion coordinated the electrostatically pre-organized active site, while the catalytic H204 adopted a solvent-exposed, inactive loop conformation. In the inhibitor complex, p-nitrophenol displaced the chloride, establishing a characteristic oxyanion hole network. Concomitantly, the “lid” loop transitioned to an open state, with H204 exhibiting pronounced conformational heterogeneity across eight independent molecules. These complementary structures provide structural evidence for conformational dynamics of the catalytic lid loop, consistent with the conformational cycling model previously proposed for a mesophilic homolog.