Search Results (80)

A real-space renormalization group (RG) framework is formulated for classical SO(n) spin models defined on d-dimensional crystal lattices composed of corner-sharing hyper-tetrahedra, a class of geometrically frustrated crystal structures. This includes, as specific instances, the classical Heisenberg model on the kagome and pyrochlore crystals. The approach involves computing the partition function and corresponding order parameters for spin clusters embedded in the crystal, to leading order in symmetry-breaking fields generated by surrounding spins. The crystal geometry plays a central role in determining the scaling relations and the associated critical behavior. To illustrate the efficacy of the method, a reduced manifold of symmetry-allowed ordered states for isotropic nearest-neighbor interactions is analyzed. The RG flow systematically excludes the emergence of a $\overrightarrow{q}=\mathbf{0}$ ordered phase within the antiferromagnetic sector, independently of both the spatial dimensionality of the crystal and the number of spin components. Extensions to incorporate more elaborate crystal-symmetry-induced ordering patterns and fluctuation-driven phenomena—such as order-by-disorder—are also discussed. Full article

The Ising model is famous in condensed matter and statistical physics. In this work we present a free-fermion formulation of the two-dimensional classical Ising models on honeycomb, triangular and Kagomé lattices. Each Ising model is studied in the cases of a zero field and of an imaginary field $i(\pi /2)k_{B}T$. We employ the decorated lattice technique, star-triangle transformation, and weak-graph expansion method to exactly map each Ising model in both cases into an eight-vertex model on the square lattice. The resulting vertex weights are shown to satisfy the free-fermion condition. In the zero-field case, each Ising model is an even free-fermion model. In the case of the imaginary field, the Ising model on the honeycomb lattice is an even free-fermion model, while the models on the triangular and Kagomé lattices are odd free-fermion models. We obtain the exact solution of the Kagomé lattice Ising model under the imaginary field $i(\pi /2)k_{B}T$, a result not previously reported in the literature. We also show that the frustrated Ising models on the triangular and Kagomé lattices in the imaginary field still exhibit a non-zero residual entropy. Full article

The topological phase of matter brings extra inspiration for efficient light manipulation. Here, we propose two-parameter tunable topological transitions based on distorted Kagome photonic crystals. By selecting specific splicing boundaries, we successfully visualize several diverse types of robust edge states and corner states. Through introducing optical vortices with tunable orbital angular momentum, we demonstrate the directional excitation of multi-dimensional topological states as needed. Furthermore, we have studied the coupling effects of multi-dimensional photonic states and the modulation of source in three typical areas. This work provides an instructive avenue for manipulating light in integrated topological photonic devices. Full article

Kagome lattices have attracted significant research interest due to their unique interplay of geometry, topology, and material properties. They provide deep insights into strongly correlated electron systems, novel quantum phases, and advanced material designs, making them fundamental in condensed matter physics and material engineering. This work presents an efficient method for terahertz (THz) wave generation across the entire THz spectrum, leveraging high-quality-factor Kagome-shaped silicon photonic crystal resonators. In the proposed simulation-based approach, an infrared (IR) single-frequency wave interacts with an induced resonance mode within the resonator, producing a THz beat frequency. This beat note is then converted into a standalone THz radiation (T-ray) wave using an amplitude demodulator. Simulations confirm the feasibility of our method, demonstrating that a conventional single-frequency wave can induce resonance and generate a stable beat frequency. The proposed technique is highly versatile, extending beyond THz generation to frequency conversion in electronics, optics, and acoustics, among other domains. Its high efficiency, compact design, and broad applicability offer a promising solution to challenges in THz technology. Furthermore, our findings establish a foundation for precise frequency manipulation, unlocking new possibilities in signal processing, sensing, detection, and communication systems. Full article

3D-Kagome lattice sandwich panels are mainly composed of upper and lower panels and a series of symmetrically and periodically arranged lattices, known for their excellent high specific stiffness, high specific strength, and energy absorption capacity. The inherent geometrical symmetry of the 3D-Kagome lattice plays a crucial role in achieving superior mechanical stability and load distribution efficiency. This structural symmetry enhances the uniformity of stress distribution, making it highly suitable for automotive vibration suppression, such as battery protection for electric vehicles. In this study, a polyurethane foam-filled, symmetry-enhanced 3D-Kagome sandwich panel is designed following an optimization of the lattice structure. A novel fabrication method combining precision wire-cutting, interlocking core assembly, and in situ foam filling is employed to ensure a high degree of integration and manufacturability of the composite structure. Its mechanical properties and energy absorption characteristics are systematically evaluated through a series of experimental tests, including quasi-static compression, three-point bending, and low-speed impact. The study analyzes the effects of core height on the structural stiffness, strength, and energy absorption capacity under varying loads, elucidating the failure mechanisms inherent to the symmetrical lattice sandwich configurations. The results show that the foam-filled sandwich panels exhibit significant improvements in mechanical performance compared to the unfilled ones. Specifically, the panels with core heights of 15 mm, 20 mm, and 25 mm demonstrate increases in bending stiffness of 47.3%, 53.5%, and 51.3%, respectively, along with corresponding increases in bending strength of 45.5%, 53.1%, and 50.9%. The experimental findings provide a fundamental understanding of foam-filled lattice sandwich structures, offering insights into their structural optimization for lightweight energy-absorbing applications. This study establishes a foundation for the development of advanced crash-resistant materials for automotive, aerospace, and protective engineering applications. This work highlights the structural advantages and crashworthiness potential of foam-filled Kagome sandwich panels, providing a promising foundation for their application in electric vehicle battery enclosures, aerospace impact shields, and advanced protective systems. Full article

Recently, web-based dietary assessment tools for the targeted population have been developed and used to estimate the dietary intake level in several epidemiological studies. This study aimed to examine the validity of estimating energy and nutrient intake by the web-based 24 h dietary recall (Web24HR), which we developed for the Japanese population. Overall, 228 adults aged ≥20 years who agreed to participate were included. Web24HR was administered three times per person: twice within 3 weeks and once 3 months later. The data on 3-day weighed food records (WFR) at 3-month intervals in the four seasons were collected using the reference method. The intake of energy and nutrients between Web24HR and WFR were compared using Pearson’s correlation coefficients and the Bland–Altman analysis. As results, the correlations were moderate for both men (median r = 0.51) and women (median r = 0.38) except for iodine, retinol, retinol equivalents, and β-tocopherol. The Bland–Altman method revealed that the bias in intake was within ±10% for most nutrients, except for cholesterol, iodine, vitamin C, and the water content, in both sexes. Additionally, monounsaturated fatty acids in men and β-cryptoxanthin in women exhibited an underestimation of more than 10%. In conclusion, the Web24HR intake assessment showed moderate correlations for most nutrients in both sexes. The bias in intake was within ±10% for most nutrients, but there were discrepancies for some nutrients. This tool’s performance is comparable to Japan’s standard dietary exposure assessment methods and will be helpful for future applications in epidemiological studies, though caution is needed for certain nutrient assessments. Full article

We investigate emergent conductive phenomena triggered by collinear antiferromagnetic orderings. We show that an up-down-zero spin configuration in a triangle cluster leads to linear and nonlinear spin conductivities even without the relativistic spin–orbit coupling; the linear spin conductivity is Drude-type, while the nonlinear spin conductivity has Hall-type characterization. We demonstrate the emergence of both spin conductivities in a breathing kagome system consisting of a triangle cluster. The nonlinear spin conductivity becomes larger than the linear one when the Fermi level lies near the region where a small partial band gap opens. Our results indicate that collinear antiferromagnets with triangular geometry give rise to rich spin conductive phenomena. Full article

Using a microscopic model and Green’s function theory, we investigated the magnetization, specific heat, and polarization properties of CaBaCo₄O₇ (CBCO), scrutinizing their variations with temperature, magnetic field strength, and doping effects. Our analysis revealed a conspicuous kink in the specific heat curve near the critical temperature ($T_C$), indicative of a phase transition. Additionally, the observed increase in polarization, P with escalating magnetic field strength serves as compelling evidence for the multiferroic nature of CBCO. Substituting Co ions with Fe ions resulted in an augmentation of the CBCO magnetization, M, while doping with Zn, Mn, or Ni ions led to a decline. Similarly, doping CBCO with Y or Sr ions at the Ca site exhibited divergent effects on magnetization, M, with an increase in the former and a decrease in the latter case. This modulation of the magnetization, M, can be attributed to the varying strains induced by the doping ions, thereby altering the exchange interaction constants within the system. The polarization, P, increases by Ni, Mn, or Zn substitution on the kagome layer Co sites. It can be concluded that Ni, Mn, or Zn doping enhances the magnetoelectric effect of CBCO. Notably, our findings align qualitatively well with experimental observations, reinforcing the validity of our theoretical framework. Full article

As the control brain of the petrochemical plant, blast-resistant performance requirements are important for the sustainability of the petrochemical control room and should be guaranteed when the vapor cloud explosion occurs in the petrochemical production process. The 3D-Kagome truss core sandwich structure is a kind of blast-resistant material with high energy absorption and recycling. Considering the influential factors of the radius of the truss core rod and thickness of the upper and lower panels, in this paper, the blast-resistant performance of a real steel petrochemical control room with a 3D-Kagome truss core sandwich wall was analyzed. With the optimization goal of plastic deformation energy and panel displacement, the optimal wall thickness and radius of the truss core rod were obtained. The optimized blast-resistant walls were assembled, and the dynamic response of the steel petrochemical control room with the 3D-Kagome truss core sandwich blast-resistant wall was analyzed. The simulation results indicate that the truss core layer is ineffective in dissipating blast energy when the radius ratio of the truss core rod exceeds 2.7% of the total wall thickness. Moreover, as the thickness of the upper and lower panels increases from 0.5 cm to 3 cm, the proportion of plastic deformation energy in the truss core layer gradually rises from 55% to 95%, stabilizing at around 90%. The optimal configuration for blast resistance is achieved when the panel thickness ratio is 6.7% of the total wall thickness; the truss core rod radius ratio is 2.7% of the total thickness. This study establishes the effectiveness of the optimized 3D-Kagome sandwich wall as a blast-resistant solution for steel petrochemical control rooms. Full article

The present study involves the precise identification and safety evaluation of Enterococcus casseliflavus KB1733, previously identified using 16S rRNA analysis, through whole-genome sequencing, phenotypic analysis, and preclinical toxicity studies. Analyses based on the genome sequencing data confirm the identity of KB1733 as E. casseliflavus and show that the genes related to vancomycin resistance are only present on the chromosome, while no virulence factor genes are present on the chromosome or plasmid. Phenotypic analyses of antibiotic resistance and hemolytic activity also indicated no safety concerns. A bacterial reverse mutation test showed there was no increase in revertant colonies of heat-killed KB1733. An acute toxicity test employing heat-killed KB1733 at a dose of 2000 mg/kg body weight in rats resulted in no deaths and no weight gain or other abnormalities in the general condition of the animals, with renal depression foci and renal cysts only occurring at the same frequency as in the control. Taking the background data into consideration, the effects on the kidneys observed in the current study were not caused by KB1733. Our findings suggest that KB1733 is non-pathogenic to humans/animals, although further studies involving repeated oral toxicity tests and/or clinical tests are required. Full article

It remains unclear how the various environmental factors are combined in practice to influence vegetable preferences in school-aged children. This study aimed to clarify the environmental factors during infancy and their association with vegetable preference in school-aged children. To find clusters of early childhood environmental factors, we conducted a factor analysis on 58 items related to early childhood environmental factors and a k-means cluster analysis using the factors obtained. The association of the extracted factors and clusters with vegetable preferences was assessed by multiple regression analysis. Twelve factors relating to vegetable eating, cooking and harvesting experience, and parental attitudes were extracted by factor analysis. Three clusters, “low awareness of experiences”, “high awareness” and “low positive encouragement”, were then extracted. In the multiple regression analysis, all 12 factors were found to be associated with vegetable preferences. Furthermore, it was found that the “high awareness” group had a significantly higher score for vegetable preference than the “low awareness of experiences” group (β = 0.56, 95% CI: 0.37–0.74). Thus, the study found that environmental factors during infancy, in isolation and combination, influenced vegetable preferences in school-aged children. Assessing the combination of various environmental factors during infancy may contribute to a better understanding of future vegetable preferences. Full article

GCN1 is recognized as a factor that is essential for the activation of GCN2, which is a sensor of amino acid starvation. This function is evolutionarily conserved from yeast to higher eukaryotes. However, recent studies have revealed non-canonical functions of GCN1 that are independent of GCN2, such as its participation in cell proliferation, apoptosis, and the immune response, beyond the borders of species. Although it is known that GCN1 and GCN2 interact with ribosomes to accomplish amino acid starvation sensing, recent studies have reported that GCN1 binds to disomes (i.e., ribosomes that collide each other), thereby regulating both the co-translational quality control and stress response. We propose that GCN1 regulates ribosome-mediated signaling by dynamically changing its partners among RWD domain-possessing proteins via unknown mechanisms. We recently demonstrated that GCN1 is essential for cell proliferation and whole-body energy regulation in mice. However, the manner in which ribosome-initiated signaling via GCN1 is related to various physiological functions warrants clarification. GCN1-mediated mechanisms and its interaction with other quality control and stress response signals should be important for proteostasis during aging and neurodegenerative diseases, and may be targeted for drug development. Full article

We develop a strong coupling approach towards quantum magnetism in Mott insulators for Wannier-obstructed bands. Despite the lack of Wannier orbitals, electrons can still singly occupy a set of exponentially localized but nonorthogonal orbitals to minimize the repulsive interaction energy. We develop a systematic method to establish an effective spin model from the electron Hamiltonian using a diagrammatic approach. The nonorthogonality of the Mott basis gives rise to multiple new channels of spin-exchange (or permutation) interactions beyond Hartree–Fock and superexchange terms. We apply this approach to a Kagome lattice model of interacting electrons in Wannier-obstructed bands (including both Chern bands and fragile topological bands). Due to the orbital nonorthogonality, as parameterized by the nearest-neighbor orbital overlap g, this model exhibits stable ferromagnetism up to a finite bandwidth $W\sim Ug$, where U is the interaction strength. This provides an explanation for the experimentally observed robust ferromagnetism in Wannier-obstructed bands. The effective spin model constructed through our approach also opens up the possibility for frustrated quantum magnetism around the ferromagnet-antiferromagnet crossover in Wannier-obstructed bands. Full article

Lipopolysaccharides are components of Gram-negative bacteria. The relationship between blood lipopolysaccharide levels and health status has mainly been investigated in Europe, and there is a lack of information about Asia, particularly Japan. This study aimed to investigate the relationship between blood lipopolysaccharide levels and health status in the Japanese. We conducted two cross-sectional studies in 36 healthy subjects (Study 1) and 36 patients with abnormal glucose metabolism (AGM; Study 2). The plasma lipopolysaccharide concentration in healthy subjects was positively correlated with body mass index. The plasma lipopolysaccharide concentration in AGM patients was obviously higher than that in healthy subjects. Furthermore, in AGM patients, the plasma lipopolysaccharide concentration was positively correlated with C-peptide, fasting plasma glucose levels, triglycerides, and stage of diabetic nephropathy. The plasma lipopolysaccharide concentration was also negatively correlated with 20/(C-peptide × fasting plasma glucose), an indicator of insulin resistance, and high-density lipoprotein cholesterol. In particular, the correlation between plasma lipopolysaccharide concentration and triglycerides in AGM patients was maintained in multiple regression analyses adjusted for age, sex, or body mass index. These results suggest a possible role of lipopolysaccharides in obesity in healthy subjects and in the deterioration of triglyceride metabolism in AGM patients in the Japanese population. Full article

Reactive oxygen species (ROS) are produced mainly by mitochondrial respiration and function as signaling molecules in the physiological range. However, ROS production is also associated with the pathogenesis of various diseases, including insulin resistance (IR) and type 2 diabetes (T2D). This review focuses on the etiology of IR and early events, especially mitochondrial ROS (mtROS) production in insulin-sensitive tissues. Importantly, IR and/or defective adipogenesis in the white adipose tissues (WAT) is thought to increase free fatty acid and ectopic lipid deposition to develop into systemic IR. Fatty acid and ceramide accumulation mediate coenzyme Q reduction and mtROS production in IR in the skeletal muscle, while coenzyme Q synthesis downregulation is also involved in mtROS production in the WAT. Obesity-related IR is associated with the downregulation of mitochondrial catabolism of branched-chain amino acids (BCAAs) in the WAT, and the accumulation of BCAA and its metabolites as biomarkers in the blood could reliably indicate future T2D. Transcription factor NF-E2-related factor 2 (Nrf2), which regulates antioxidant enzyme expression in response to oxidative stress, is downregulated in insulin-resistant tissues. However, Nrf2 inducers, such as sulforaphane, could restore Nrf2 and target gene expression and attenuate IR in multiple tissues, including the WAT. Full article