Kochi University of Technology

According to ourhypothesis that ortho (O) to para (P) hydrogenconversion is promoted by an inhomogeneous electric field on the surfaceof the insulating oxide with high ionicity, we searched for OP conversioncatalysts using lattice energy as an indicator of high ionicity. Asa result, we found new oxide catalysts, including SiO2,γ-Al2O3, and CeO2 combinedwith 3d late transition metal cocatalysts. The fraction of para-H2 on 5%Fe-loaded SiO2 powder reached 50% (equilibriumvalue at 77 K) within 20 min. The activities of these catalysts aresignificantly superior to those of benchmark catalysts, such as Mn3O4. The cocatalyst nanoparticles of 1–12nm size dispersed on the oxide catalysts adsorb hydrogen well withoutdissociating it. The nuclear spin state of ortho-H2 adsorbedat the asymmetric site (nonzero electric field gradient) of the oxidesurface is thermally excited by nuclear quadrupole interaction, andthe OP conversion rate is increased by nuclear spin relaxation.

With inherent negative stiffness and nonlinearity, reluctance magnetic levitation systems struggle to sustain satisfactory control performance across a long stroke. To address this issue, theoretical analysis, control strategy design, and experiments are performed. First, the magnetic and dynamic behavior are analyzed, and the corresponding mathematical model is derived. Then, the control system analysis is conducted, and the feedback properties are described from a physically intuitive perspective. Moreover, with a standard PD/PID compensator, a clear trade-off emerges between robustness at small air gaps and tracking performance at large air gaps. Subsequently, a control strategy combining feedforward compensation with gain scheduling PD is designed. It is directly mapped from the reluctance actuator parameters without relying on engineering experience and can be flexibly configured to meet performance requirements. Finally, time-domain and frequency-domain experiments are conducted. The positioning control results show that the proposed strategy effectively shortens the settling time of long-stroke step responses and improves the uniformity of the dynamic performance. The frequency response evidence shows a more uniform response over the full stroke and simultaneous improvements in robustness and tracking, effectively resolving the long-stroke conflict.

Noisy galvanic vestibular stimulation (nGVS) can improve postural stability by delivering subthreshold electrical noise to the vestibular system. However, the frequency-specific effects of nGVS on postural control responses-particularly those involving the center of mass (COM) recovery force and movement strategies-remain unclear. We investigated how different nGVS frequencies affect postural control, estimating COM fluctuations using a rigid pendulum model. Thirty-two healthy adults (mean age, 20.3±1.2years; 19 females) underwent three interventions: sham nGVS, low-frequency nGVS (LF-nGVS, 0-100Hz), or high-frequency nGVS (HF-nGVS, 100-640Hz), each with a 200 µA current (0 µA for the sham). During each 40-s trial, participants stood on a platform with eyes closed and the middle 30s were analyzed. Inertial measurement units were affixed to the occipital protuberance to capture head kinematics. Postural control was assessed using conventional metrics (e.g., center of foot pressure [COP], COM sway, and head acceleration) and novel indicators of COM recovery force and head acceleration control based on motor strategies. Both LF-nGVS and HF-nGVS significantly reduced several indices, including COP velocity and head angular velocity, compared with sham stimulation. No significant differences were observed between LF-nGVS and HF-nGVS. Head acceleration was significantly correlated with COM recovery force and joint movement strategies in both stimulation conditions. Although the mechanism of neural network activity at different stimulation frequencies requires careful interpretation, these findings suggest that COM recovery and associated motor strategies contribute to nGVS-induced postural improvements, providing insights into its neuromechanistic effects.

β-Formyl-β-nitroenamine (FNE), which possesses multiple functionalities, including formyl, amino, and nitro groups, in addition to a C=C double bond with biased electron density, exhibits versatile reactivities. The two electrophilic sites react with dinucleophiles to afford nitro-substituted heterocycles. When the nucleophilic amino group and the electrophilic formyl group are reacted, polyfunctionalized pyridines are readily synthesized upon treatment with active methylene compounds. In addition, the biased electron density of the FNE molecule facilitates [4+2] or [4+4] cycloaddition. FNE is soluble in most organic solvents, is nonexplosive, and can be safely handled. Products with both electron-donating and electron-withdrawing groups are obtained; therefore, the push–pull property of FNE is transcribed to the product. These compounds play a crucial role in the development of optical and electronic materials, giving FNE exceptionally high synthetic utility.

The game 2048 has attracted millions of people with its simple yet challenging gameplay, leading to the development of numerous computer players. Most successful computer players for 2048 use evaluation functions trained through temporal difference learning (TD learning) or its variants. While TD learning is highly effective and can improve evaluation functions quickly, the performance of these functions often plateaus after a certain number of timesteps. Therefore, it is important to refine those evaluation functions to further enhance the performance of computer players. In this paper, we extend the conventional TD learning approach and propose two refinement algorithms for 2048. Firstly, we conducted detailed experiments to refine the best open-source neural network, and achieved significant performance improvements, increasing the average score from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2.49 \times 10^{5}$</tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$3.37 \times 10^{5}$</tex-math></inline-formula> in greedy play (1-ply lookahead) and from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$4.87 \times 10^{5}$</tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$5.45 \times 10^{5}$</tex-math></inline-formula> with 3-ply expectimax search. We also applied our refinement method to the state-of-the-art N-tuple network, improving the average score from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$5.85\times 10^{5}$</tex-math></inline-formula> to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$6.10\times 10^{5}$</tex-math></inline-formula> with 6-ply expectimax search and the tile-downgrading trick.

Solution-processed SnO2-based thin-film transistors (TFTs) have attracted significant attention due to their low cost, low toxicity, and the high abundance of SnO2. However, SnO2-TFTs suffer from large negative threshold voltage as well as low on/off ratios because of high residual carrier electrons from oxygen vacancies. It is known that doping elements, such as Si, that form strong chemical bonding with oxygen suppresses oxygen vacancy formation. Here, we fabricated and characterized Si-doped SnO2 (SixSnyO) TFTs. In SixSnyO-TFTs, we found that increasing the Sn molarity leads to an enhancement in field-effect mobility while inducing a negative threshold voltage shift. To clarify the origin of this mechanism, we measured the effective channel thickness of SixSnyO-TFTs by electric field thermopower modulation analyses. The effective mass (m*) of the SixSnyO films slightly decreased with increasing Sn molarity and was approximately 0.15 m0, suggesting that an increase in Sn molarity improves the metal–oxygen network in the film. The effective channel thickness, which corresponds to the accumulation layer thickness, increased with rising sheet carrier concentration at low Sn molarity. On the other hand, it decreased with increasing sheet carrier concentration at high Sn molarity. This suggests that the carrier transport mechanism varies depending on Sn molarity. These findings provide guidance in developing high-mobility and reliable SixSnyO-TFTs through appropriate control of the Sn molarity in SixSnyO.

High-skilled esports players have unique cortical activity and gaze control, both of which are closely linked to their performance. To enhance key aspects of esports performance—shot time and accuracy—the current study implemented two training methods: a cortical activity-based method (Experiment 1) and a gaze control-based method (Experiment 2). In Experiment 1, a three-channel electroencephalogram headset was used to provide participants with real-time feedback on central lobe activity associated with sustained attention. Twenty-one participants were randomly assigned to the training group (10 participants) and sham group (11 participants). The training group received auditory feedback based on the power of theta and alpha power, while the sham group received auditory feedback not related to central lobe activity. In Experiment 2, an eye-tracker was used to measure the gaze movement and provide feedback. The feedback was provided to help participants maintain their gaze on-center. Twenty-one participants were randomly assigned to the training group (11 participants) and the sham group (10 participants). The training group received warning sounds when their gaze deviated from the off-center, promoting centralized gaze control, whereas the sham group received no such feedback. Participants‘ age and gaming experience were controlled to minimize confounding factors. The results demonstrated a significant decrease in shot time for the training group in both Experiment 1 (Mdn = -30.3ms) and Experiment 2 (Mdn = -47.2ms), with no significant changes in the sham group (all p > .05). Therefore, biofeedback training methods can reduce shot time, one of the critical performance indicators in esports. • We implement attention training and peripheral vision methods for enhancing the reaction speed and accuracy of esports players. • Attention training significantly reduced shot times (Mdn: -30.3ms) in esports players by improving their attention, and the result was supported by a reduction in central alpha power. • Peripheral vision training significantly reduced shot times (Mdn: -47.2ms) in esports players by enhancing peripheral vision skills, and this finding was supported by a narrower gaze distribution. • This reduction in shot time was achieved without a significant reduction in accuracy.

A hybrid laser welding system was developed to enable high-speed, spatter-suppressed joining of pure copper conductors, aimed at applications such as electric motor manufacturing. The system combines a 2 kW infrared (IR) single-mode fiber laser with a 3 kW blue diode laser, along with a high-speed galvanometer scanner for precise beam control. The blue laser, exhibiting high absorption in solid copper, initiates rapid surface melting, while the IR laser efficiently forms a keyhole by leveraging enhanced absorption in the liquid phase. Experiments on 2 × 4 mm copper wires revealed that increasing the scan speed reduced weld size, primarily due to decreased energy absorption associated with shallower keyhole formation. Spatter evaluation using high-speed imaging showed a significant reduction in spatter at higher scan speeds. A scan speed of 1500 mm/s was identified as optimal, achieving a weld length of 2 mm within 0.15 s while minimizing spatter. These results demonstrate the effectiveness of the hybrid laser configuration in achieving efficient, high-quality copper welding suitable for high-throughput industrial applications.

Ductile deformation and fracture of solid Ni nanorod fillers inside multiwalled carbon nanotubes were induced using the force induced by electromigration in a transmission electron microscope. The ductile elongation caused partial or full flattening of some host nanotubes, whereas other tubes remained cylindrical during the ductile process. The presence or absence of flattening of the host tubes was examined in terms of diameter, wall thickness, and magnitude of electric current.