Logarithmic Behaviours in the Feigin-Fuchs Construction of the c=-2 Conformal Field Theory

We obtain logarithmic behaviours of a four-point correlation function in the c=-2 conformal field theory by using the Feigin-Fuchs construction. It becomes an indeterminate form by a naive evaluation, but is obtained by introducing an appropriate regularization procedure.Comment: LaTeX, 7 page

Phase structure of linear quiver gauge theories from anomaly matching

We consider the phase structure of the linear quiver gauge theory, using the 't Hooft anomaly matching condition. This theory is characterized by the length $K$ of the quiver diagram. When $K$ is even, the symmetry and its anomaly are the same as those of massless QCD. Therefore, one can expect that the spontaneous symmetry breaking similar to the chiral symmetry breaking occurs. On the other hand, when $K$ is odd, the anomaly matching condition is satisfied by the massless composite fermions. We also consider the thermal partition function under the twisted boundary conditions. When $K$ is even, from the anomaly at finite temperature, we estimate the relation between the critical temperatures associated with the confinement/deconfinement and the breaking of the global symmetry. Finally we discuss the anomaly matching at finite temperature when $K$ is odd.Comment: 20 pages, 6 figure

Local stress tensor calculation by the method-of-plane in microscopic systems with macroscopic flow: A formulation based on the velocity distribution function

Kusudo H., Omori T., Yamaguchi Y.. Journal of Chemical Physics 155(18), 184103 (2021); licensed under a Creative Commons Attribution (CC BY) license.In this work, we developed a calculation method of local stress tensor applicable to non-equilibrium molecular dynamics (NEMD) systems, which evaluates the macroscopic momentum advection and the kinetic term of the stress in the framework of the Method-of-Plane (MoP), in a consistent way to guarantee the mass and momentum conservation. From the relation between the macroscopic velocity distribution function and the microscopic molecular passage across a fixed control plane, we derived a method to calculate the basic properties of the macroscopic momentum conservation law including the density, the velocity, the momentum flux, and the two terms of the stress tensor, i.e., the interaction and the kinetic terms, defined on a surface with a finite area. Any component of the streaming velocity can be obtained on a control surface, which enables the separation of the kinetic momentum flux into the advection and stress terms in the framework of MoP, and this enables strict satisfaction of the mass and momentum conservation for an arbitrary closed control volume (CV) set in NEMD systems. We validated the present method through the extraction of the density, velocity, and stress distributions in a quasi-one-dimensional steady-state Couette flow system and in a quasi-2D steady-state NEMD system with a moving contact line. We showed that with the present MoP, in contrast to the volume average method, the conservation law was satisfied even for a CV set around the moving contact line, which was located in a strongly inhomogeneous region

Reduction of spatter generation using atmospheric gas in laser powder bed fusion of Ti-6Al-4V

Laser powder bed fusion (LPBF), a typical additive manufacturing (AM) process, is a promising approach that enables high-accuracy manufacturing of arbitrary structures; therefore, it has been utilized in the aerospace and medical fields. However, several unexplained phenomena significantly affect the quality of fabricated components. In particular, it has been reported that the generation of spatters adversely affects the stability of fabrication process and degrades the performance of the fabricated components. To realize high-quality components, it is essential to suppress the generation of spatters. Thus far, the suppression of spatter generation has been attempted based on the process parameters; however, this has not been adequately discussed in terms of the fabrication atmosphere. Therefore, in this study, we focused on the fabrication atmosphere and investigated spatter generation using gas with different physical properties rather than conventionally used argon. It was observed that the spatter generation during the fabrication of the Ti6Al4V alloy could be significantly suppressed by changing the atmospheric gas, even under constant LPBF process parameters. We proved that the fabrication atmosphere is an important factor to be considered, apart from the process parameters, in AM technology.Amano H., Yamaguchi Y., Ishimoto T., et al. Reduction of spatter generation using atmospheric gas in laser powder bed fusion of Ti-6Al-4V. Materials Transactions 62, 1225 (2021); https://doi.org/10.2320/matertrans.MT-M2021059

Quantifying interfacial tensions of surface nanobubbles: How far can Young's equation explain?

Nanobubbles at solid-liquid interfaces play a key role in various physicochemical phenomena and it is crucial to understand their unique properties. However, little is known about their interfacial tensions due to the lack of reliable calculation methods. Based on mechanical and thermodynamic insights, we quantified for the first time the liquid-gas, solid-liquid, and solid-gas interfacial tensions of submicron-sized nitrogen bubbles at graphite-water interfaces using molecular dynamics (MD) analysis. It was revealed that Young's equation holds even for nanobubbles with different radii. We found that the liquid-gas and solid-liquid interfacial tensions were not largely affected by the gas density inside the nanobubbles. In contrast, the size effect on the solid-gas interfacial tension was observed, namely, the value dramatically decreased upon an increase in the gas density due to gas adsorption on the solid surface. However, our quantitative evaluation also revealed that the gas density effect on the contact angles is negligible when the footprint radius is larger than 50 nm, which is a typical range observed in experiments, and thus the flat shape and stabilization of submicron-sized surface bubbles observed in experiments cannot be explained only by the changes in interfacial tensions due to the van der Waals interaction-induced gas adsorption, namely by Young's equation without introducing the pinning effect. Based on our analysis, it was clarified that additional factors such as the differences in the studied systems are needed to explain the unresolved open issues-a satisfactory explanation for the nanobubbles in MD simulations being ultradense, non-flat, and stable without pinning.Teshima H., Kusudo H., Bistafa C., et al. Quantifying interfacial tensions of surface nanobubbles: How far can Young's equation explain?. Nanoscale 14, 2446 (2022); https://doi.org/10.1039/d1nr07428h

<ORIGINAL ARTICLE>Long-term follow-up of combined maxillary protraction appliance and chincap treatment

著しい骨格性反対咬合症例の治療において,我々は上顎前方牽引装置とchin capの併用により,顎関係の改善を行うことを含めた長期的管理を行っている。今回我々は骨格性反対咬合と診断され,治療を行った女子3症例の長期的観察を通し検討,考察を行った。これらの症例において,第一段階では上顎前方牽引装置とchin capにより顎関係を改善した。上顎前方牽引装置除去後,上顎は成長期間中位置変化を殆ど示さなかった。その間,下顎は予測よりも大きな成長を示した。咬合関係はすべての症例において成人期まで維持されていた。しかしこれらの症例は思春期成長の後も,下顎の前方成長により,わずかな後戻引頃向を示した。以上のことから,後戻りを予防するために反対咬合の治療においてはオーバーコレクションと第一段階後の下顎の成長のコントロールが必要であると考えられた。In an attempt to distinguish between long-term treatment effects and growth change, the present study evaluates the real post-treatment changes following maxillary protraction treatment after correction for the orthopedic effects which three female patients were investigated. Our proposed treatment plan for skeletal Class III patients consists of 3 stages. In the firststage, a maxillary protraction appliance and a chincap are used together to correct the intermaxillary relationship. After removal of the maxillary protraction appliance, the maxilla remains relatively stable during the growth stage. However, the mandible tends to experience overgrowth, which results in a relapse. The occlusal relationship was maintained until the adultstage in all cases. However, they experienced slight relapse, manifested by mandibular forward growth following removal of the maxillary protraction appliance. Therefore, overcorrection of reversed occlusion and control of mandibular growth after the first stage must be performed in order to prevent relapse

Improved Electrochemical Performance of a GexS1-x Alloy Negative Electrode for Lithium-Ion Batteries

A GexSi1−x alloy electrode is useful for addressing the shortcomings of a Si negative electrode for lithium-ion batteries. To further improve the electrochemical performance of a GexSi1−x negative electrode, a film-forming additive and the formation of a composite with LaSi2 were applied. A Ge0.1Si0.9 electrode exhibited better cyclability in the additive-containing electrolyte with a discharge capacity of 1240 mA h g−1 at the 400th cycle. In addition, a Ge0.1Si0.9/LaSi2 composite electrode showed better cycle performance than a Ge0.1Si0.9 electrode