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Large negative magnetoresistance in the off-stoichiometric topological semimetal PrSbxTe2−x

Physical Review B 2025年第2期111卷 024421-024421页

作者： Gokul Acharya Krishna Pandey M. M. Sharma Jian Wang Santosh Karki Chhetri Md Rafique Un Nabi Dinesh Upreti Rabindra Basnet Josh Sakon Department of Physics University of Arkansas Fayetteville Arkansas 72701 USA Materials Science and Engineering Program Institute for Nanoscience and Engineering University of Arkansas Fayetteville Arkansas 72701 USA Department of Chemistry and Biochemistry Wichita State University Wichita Kansas 67260 USA Department of Chemistry & Physics University of Arkansas at Pine Bluff Pine Bluff Arkansas 71603 USA Department of Chemistry and Biochemistry University of Arkansas Fayetteville Arkansas 72701 USA

Magnetic topological materials LnSbTe (Ln = lanthanide) have attracted intensive attention because of the presence of interplay between magnetism, topological, and electron correlations depending on the choices of magnetic Ln elements. Varying Sb and Te composition is an efficient approach to control structural, magnetic, and electronic properties. Here, we report on the composition-dependent properties in PrSbxTe2−x. We identified the tetragonal-to-orthorhombic structure transitions in this material system and very large negative magnetoresistance in the x=0.3 composition, which might be ascribed to the coupling between magnetism and transport. Such unusual magnetotransport enables PrSbxTe2−x topological materials as a promising platform for device applications.

关键词： Magnetoresistance

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Cytocompatible and antibacterial Fe-, Cu- and Zn-substituted calcium hydroxyapatite materials for skin applications

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Ceramics International 2025年第9期51卷 11286-11296页

作者： Lukaviciute, L. Lukowiak, A. Stankeviciute, Z. Junka, A. Mortimer, M. Zarkov, A. Yang, J.-C. Ganceviciene, R. Kareiva, A. Faculty of Chemistry and Geosciences Vilnius University Naugarduko st. 24 Vilnius03225 Lithuania Institute of Low Temperature and Structure Research Polish Academy of Sciences Okolna 2 Wroclaw50422 Poland Department of Pharmaceutical Microbiology and Parasitology Wroclaw Medical University Borowska 211A Wroclaw50556 Poland Laboratory of Environmental Toxicology National Institute of Chemical Physics and Biophysics Akadeemia tee 23 Tallinn12618 Estonia Graduate Institute of Nanomedicine and Medical Engineering International Ph.D. Program in Biomedical Engineering College of Biomedical Engineering Research Center of Biomedical Device Research Center of Digital Oral Science and Technology Taipei Medical University Taiwan Faculty of Medicine Vilnius University M.K. Ciurlionio st. 21 Vilnius03101 Lithuania

Calcium hydroxyapatite (C10(PO4)6(OH)2;CHAp) and metal-substituted samples (Fe:CHAp, Cu:CHAp, and Zn:CHAp) were synthesized using a recently developed method. This method involved the wet precipitation of amorphous calcium phosphate (ACP), followed by solid-state reaction synthesis of α-tricalcium phosphate (α-TCP), and finally hydrothermal synthesis of CHAp. The effect of Fe3+, Cu2+, and Zn2+ substitution on the phase purity and antimicrobial properties of CHAp are summarized in this study. Notably, it highlights the phase purity of CHAp and Zn:CHAp (in the presence of Fe3+ and Cu2+ ions, the α- and β-TCP phases have formed) as well as the antimicrobial activity of Zn:CHAp and Cu:CHAp against Staphylococcus aureus and Candida albicans. The synthesized nanosized CHAp, Fe:CHAp, Cu:CHAp, and Zn:CHAp samples were used as additives in the preparation of skin creams. In vitro biological studies of the resulting skin creams demonstrated their antimicrobial activity against Pseudomonas aeruginosa, and showed a reduction in osteoblasts cells viability of in the range of 20–40 %. The addition of zinc enhances antimicrobial efficacy but reduces biocompatibility, while copper maintains both high antimicrobial activity and biocompatibility, making it more suitable for the development of medical or cosmetic materials. Dermal creams containing CHAp with copper and iron ions also show significant antimicrobial activity while preserving good cell viability. These results highlight the importance of optimizing the balance between antimicrobial effectiveness and biocompatibility in these materials. © 2024

关键词： Biocompatibility

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Projecting Assumptions: The Duality Between Sparse Autoencoders and Concept Geometry

arXiv

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arXiv 2025年

作者： Hindupur, Sai Sumedh R. Lubana, Ekdeep Singh Fel, Thomas Ba, Demba School of Engineering and Applied Science Harvard University United States CBS-NTT Program in Physics of Intelligence Harvard University United States Kempner Institute Harvard University United States

Sparse Autoencoders (SAEs) are widely used to interpret neural networks by identifying meaningful concepts from their representations. However, do SAEs truly uncover all concepts a model relies on, or are they inherently biased toward certain kinds of concepts? We introduce a unified framework that recasts SAEs as solutions to a bilevel optimization problem, revealing a fundamental challenge: each SAE imposes structural assumptions about how concepts are encoded in model representations, which in turn shapes what it can and cannot detect. This means different SAEs are not interchangeable—switching architectures can expose entirely new concepts or obscure existing ones. To systematically probe this effect, we evaluate SAEs across a spectrum of settings: from controlled toy models that isolate key variables, to semi-synthetic experiments on real model activations and finally to large-scale, naturalistic datasets. Across this progression, we examine two fundamental properties that real-world concepts often exhibit: heterogeneity in intrinsic dimensionality (some concepts are inherently low-dimensional, others are not) and nonlinear separability. We show that SAEs fail to recover concepts when these properties are ignored, and we design a new SAE that explicitly incorporates both, enabling the discovery of previously hidden concepts and reinforcing our theoretical insights. Our findings challenge the idea of a universal SAE and underscores the need for architecture-specific choices in model interpretability. Overall, we argue an SAE does not just reveal concepts—it determines what can be seen at all. Copyright © 2025, The Authors. All rights reserved.

关键词： Neural networks

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Unavoidable multilevel biaxial symmetry breaking in chiral hybrid liquid crystals

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Physical Review E 2025年第4期111卷 045410-045410页

作者： Jin-Sheng Wu Marina Torres Lázaro Souvik Ghosh Haridas Mundoor Henricus H. Wensink Ivan I. Smalyukh Department of Physics and Chemical Physics Program University of Colorado Boulder Colorado 80309 USA Laboratoire de Physique des Solides–UMR 8502 Université Paris-Saclay and CNRS 91405 Orsay France International Institute for Sustainability with Knotted Chiral Meta Matter Hiroshima University Higashihiroshima Japan Department of Electrical Computer and Energy Engineering Materials Science and Engineering Program and Soft Materials Research Center University of Colorado Boulder Colorado 80309 USA Renewable and Sustainable Energy Institute National Renewable Energy Laboratory and University of Colorado Boulder Colorado 80309 USA

Chiral nematic or cholesteric liquid crystals (LCs) are fluid mesophases with long-ranged orientational order featuring a quasilayered periodicity imparted by a helical director configuration but lacking long-range positional order. Doping molecular cholesteric LCs with strongly anisotropic uniaxial colloidal particles adds another level of complexity because of the interplay between weak surface-anchoring boundary conditions and bulk-based elastic distortions near the particle-LC interface. Using cylindrical colloidal disks and rods with different geometric shapes and surface conditions, we demonstrate that these colloidal inclusions generically exhibit biaxial orientational probability distributions which may impart anomalously strong local biaxiality onto the hybrid cholesteric LC structure. Unlike nonchiral hybrid molecular-colloidal LCs, where biaxial order emerges only at critical colloid volume fractions exceeding some uniaxial-biaxial transition value, the orientational probability of the colloidal inclusions immersed in chiral nematic hosts is unambiguously biaxial even at infinite dilution. We demonstrate that the colloids induce local biaxial perturbations within the molecular orientational order of the LC host medium which strongly enhances the weak but native biaxial order of chiral nematic LC induced by the chiral symmetry breaking of the director field. With the help of analytical modeling and computer simulations based on the Landau–de Gennes free energy of the host LC around the colloids, we rationalize the observed multilevel biaxial order and conclude that it is not only unavoidable but also strongly enhanced compared to both achiral hybrid LCs and purely molecular cholesteric LCs.

关键词： Cholesteric liquid crystals

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Insights into the role of metal dopant on ammonia decomposition over graphene-supported Ni6, Ni5Pt, and Ni5Rh clusters

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International Journal of Hydrogen Energy 2025年 130卷 168-175页

作者： Yusuf, Alfani Budiantono, Reva Juangsa, Firman Bagja Aziz, Muhammad Budiyanto, Muhammad Arif Saputro, Adhitya Gandaryus Mahyuddin, Muhammad Haris Graduate Program of Engineering Physics Faculty of Industrial Technology Institut Teknologi Bandung Jl. Ganesha 10 Bandung40132 Indonesia PLN Nusantara Power UMRO Jl. Pluit Karang Ayu Barat No. 1 Jakarta14450 Indonesia Thermal Science and Engineering Research Group Faculty of Mechanical and Aerospace Engineering Institut Teknologi Bandung Jl Ganesha 10 Bandung40132 Indonesia Institute of Industrial Science The University of Tokyo 4-6-1 Komaba Meguro-ku Tokyo153-8505 Japan Department of Mechanical Engineering Universitas Indonesia Depok16424 Indonesia Quantum and Nano Technology Research Group Faculty of Industrial Technology Institut Teknologi Bandung Jl. Ganesha 10 Bandung40132 Indonesia Research Center for Nanoscience and Nanotechnology Institut Teknologi Bandung Jl. Ganesha 10 Bandung40132 Indonesia

Ammonia (NH3) is a promising hydrogen (H2) carrier, owing to its high hydrogen content and ease of storage. However, efficient catalytic decomposition of NH3 to H2 remains challenging. This study investigates the catalytic activity of graphene-supported Ni6, Ni5Pt, and Ni5Rh clusters for NH3 decomposition to N2 and H2 using density functional theory (DFT) calculations. The results show that the addition of Pt and Rh dopants weakens the adsorption of intermediates formed during the NH3 dehydrogenation step and slightly increases the activation energies. Interestingly, however, this drawback becomes a key factor in enhancing the activity of the subsequent N–N association and H–H recombination steps, which are critical for the reaction to cycle. Our electronic structure analysis reveals that the decreased activity in the NH3 dehydrogenation step but increased activity in the N2 and H2 formation steps are due to the ligand effect exerted by Pt and Rh. Specifically, since the metal dopants have higher electronegativities than Ni, the number of electrons at the preferred Ni-edge site decreases and eventually weakens the adsorption. Furthermore, the spatially broad nature of the Pt-5d and Rh-4d orbitals delocalizes the cluster's electron distribution, which weakens the 2N and 2H adsorption and thus eases the N2 and H2 formation. This study provides insights into the role of noble metal dopants in optimizing Ni-based catalysts for NH3 decomposition, paving the way for efficient H2 utility technologies. © 2025 Hydrogen Energy Publications LLC

关键词： Dehydrogenation

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Node-Level Lymph Node Automatic Segmentation in CT Images Using Deep Parallel Structure-Related 3D U-Net Variant 21st

Node-Level Lymph Node Automatic Segmentation in CT Images Us...

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21st Pacific Rim International Conference on Artificial Intelligence, PRICAI 2024

作者： Cheng, Shi Li, Quan Zhang, Guangyu Zhang, Lei Peng, Tao School of Future Science and Engineering Soochow University Suzhou China Center of Stomatology The Second Affiliated Hospital of Soochow University Suzhou China Division of Cardiology Department of Internal Medicine Tongji Hospital Tongji Medical College Huazhong University of Science and Technology Wuhan China Graduate Program of Medical Physics and Data Science Research Center Duke Kunshan University Jiangsu Kunshan China

ISBN: (纸本)9789819601240

The delineation of Lymph Nodes (LNs) is pivotal in pinpointing therapeutic targets for radiotherapy in head and neck malignancies. Nevertheless, this endeavor poses a formidable challenge, primarily stemming from the suboptimal contrast against adjacent tissues. This investigation introduces a deep learning methodology aimed at automating the segmentation of LNs within CT scans, offering the following contributions: (1) Expanding upon the 3D Unet model, we incorporate a parallel block consisting of attention gate and squeeze & excitation modules. We extensively evaluate various versions of this parallel block and achieve favorable performance. (2) To address the slow decrease in Dice loss, we introduce a lightweight boundary refinement module. Our proposed method is assessed on a dataset comprising 103 patients and 603 Lymph Nodes (LNs), with 452 nodes used for training and 151 nodes for testing. The node-level Dice similarity coefficient achieved by our method reaches an impressive 0.833. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.

关键词： Computerized tomography

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Observation of Photonic Chiral Flatbands

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Physical Review Letters 2025年第10期134卷 103801-103801页

作者： Minho Choi Andrea Alù Arka Majumdar Department of Electrical and Computer Engineering University of Washington Seattle Washington 98195 USA Photonics Initiative Advanced Science Research Center City University of New York New York New York 10031 USA and Physics Program Graduate Center City University of New York New York New York 10031 USA Department of Electrical and Computer Engineering University of Washington Seattle Washington 98195 USA and Department of Physics University of Washington Seattle Washington 98195 USA

Distinct selectivity to the spin angular momenta of photons has garnered significant attention in recent years, for its relevance in basic science and for imaging and sensing applications. While nonlocal metasurfaces with strong chiral responses to the incident light have been reported, these responses are typically limited to a narrow range of incident angles. In this study, we demonstrate a nonlocal metasurface that showcases strong chirality, characterized by circular dichroism (∼0.6), over a wide range of incident angles ±5°. Its quality factor, circular dichroism and resonant frequency can be optimized by design. These findings pave the way to further advance the development of valley-selective optical cavities and augmented reality applications.

关键词： Natural frequencies

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Spin nematic order and superconductivity in J1-J2 Kondo lattice model on square lattice

arXiv

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arXiv 2025年

作者： Uraga, Sho Tada, Yasuhiro Quantum Matter Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima Higashihiroshima739-8530 Japan Institute for Solid State Physics University of Tokyo Kashiwa277-8581 Japan

We investigate competition and cooperation of magnetic frustration and the Kondo effect in the J1-J2 Kondo lattice model on the square lattice at zero temperature. In this model, the frustrated interactions J1,J2 between the localized spins stabilize spin nematic orders, while the Kondo coupling favors local spin singlets. Using the slave boson mean field approximation, we find that the spin nematic order remains stable against small Kondo coupling, and the localized spins and the conduction electrons are effectively decoupled. On the other hand, a standard Fermi liquid state is formed for sufficiently strong Kondo interactions. Furthermore, in an intermediate region with moderate Kondo coupling, the spin nematic order and the Kondo effect coexist, and superconducting pairing of the conduction electrons is induced by the spinon pairing. We discuss the ground state phase diagram and nature of the quantum phase transitions between the different superconducting states. Copyright © 2025, The Authors. All rights reserved.

关键词： Fermi liquids

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Bandgap of Epitaxial Single-Crystal BiFe1−xMnxO3 Films Grown Directly on SrTiO3/Si(001)

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Materials 2025年第9期18卷 2022-2022页

作者： Cantrell, Samuel R. Miracle, John T. Cottier, Ryan J. Lindsey, Skyler Theodoropoulou, Nikoleta Materials Science Engineering and Commercialization Program Texas State University San MarcosTX78666 United States Department of Physics Texas State University San MarcosTX78666 United States

We report the growth and optical characterization of single-crystal BiFe1−xMnxO3 thin films directly on SrTiO3/Si(001) substrates using molecular beam epitaxy. X-ray diffraction confirmed epitaxial growth, film crystallinity, and sharp interface quality. Scanning electron microscopy and energy dispersive X-ray spectroscopy verified uniform film morphology and successful Mn incorporation. Spectroscopic ellipsometry revealed a systematic bandgap reduction with increasing Mn concentration, from 2.7 eV in BiFeO3 to 2.58 eV in BiFe0.74Mn0.26O3, consistent with previous reports on Mn-doped BiFeO3. These findings highlight the potential of BiFe1₋xMnxO3 films for bandgap engineering, advancing their integration into silicon-compatible multifunctional optoelectronic and photovoltaic applications. © 2025 by the authors.

关键词： Molecular beam epitaxy

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Stability of quasi-particle creation and multiband geometry in fractional Chern insulators under magnetic fields

arXiv

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arXiv 2025年

作者： Higashino, Nozomi Tada, Yasuhiro Quantum Matter Program Graduate School of Advanced Science and Engineering Hiroshima University Hiroshima Higashihiroshima739-8530 Japan Institute for Solid State Physics University of Tokyo Kashiwa277-8581 Japan

We study creation of quasi-particles in fractional Chern insulators (FCI) under magnetic fields. We consider two representative models, the Kapit-Mueller model and the checkerboard model, which have distinct band properties in terms of the quantum geometry. The former satisfies the so-called ideal condition and well mimics the lowest Landau level, while the latter is not ideal for realization of FCI states. It is found within exact diagonalization that both quasi-holes and quasi-electrons are stably created by the magnetic fields in the Kapit-Mueller model. On the other hand, stability of the quasi-particle creation depends on directions of the magnetic field in the checkerboard model. Although the quasi-electron creation is stable under a magnetic field, the quasi-hole creation and the underlying FCI state are unstable for the opposite field direction, leading to a field-induced non-FCI state. We point out that this difference can be understood based on the multiband quantum geometry in the presence of the magnetic fields. Copyright © 2025, The Authors. All rights reserved.

关键词： Magnetic fields

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