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arXiv 2024年

作者： Stratton, Benjamin Hsieh, Chung-Yun Skrzypczyk, Paul Quantum Engineering Centre for Doctoral Training H. H. Wills Physics Laboratory Department of Electrical & Electronic Engineering University of Bristol BS8 1FD United Kingdom H.H. Wills Physics Laboratory University of Bristol Tyndall Avenue BristolBS8 1TL United Kingdom CIFAR Azrieli Global Scholars Program CIFAR Toronto Canada

The Choi-state is an indispensable tool in the study and analysis of quantum channels. Considering a channel in terms of its associated Choi-state can greatly simplify problems. It also offers an alternative approach to the characterisation of a channel, with properties of the Choi-state providing novel insight into a channel's behaviour. The rank of a Choi-state, termed the Choi-rank, has proven to be an important characterising property, and here, its significance is further elucidated through an operational interpretation. The Choi-rank is shown to provide a universal bound on how successfully two agents, Alice and Bob, can perform an entanglementassisted exclusion task. The task can be considered an extension of super-dense coding, where Bob can only output information about Alice's encoded bit-string with certainty. Conclusive state exclusion, in place of state discrimination, is therefore considered at the culmination of the super-dense coding protocol. In order to prove this result, a necessary condition for conclusive k-state exclusion of a set of states is presented in order to achieve this result, and the notions of weak and strong exclusion are introduced. Copyright © 2024, The Authors. All rights reserved.

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Phonon dynamics and magnetodielectric relaxation in distorted honeycomb ferrimagnet Ni4Nb2O9: Experiment and first-principles study

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Physical Review Materials 2025年第4期9卷 045202-045202页

作者： Harshita Singh Sobhit Singh Sayandeep Ghosh Prativa Pramanik Vasant Sathe Roland Mathieu Wilfrid Prellier Subhash Thota Department of Physics Indian Institute of Technology Guwahati Assam 781039 India Department of Mechanical Engineering University of Rochester Rochester New York 14627 USA Materials Science Program University of Rochester Rochester New York 14627 USA Department of Physics Chungnam National University Daejeon 34134 Republic of Korea Department of Physics Kunsan National University Gunsan 54150 Republic of Korea Department of Materials Science and Engineering Uppsala University Uppsala SE-75103 Sweden UGC DAE Consortium for Scientific Research Indore 452 001 India Laboratoire CRISMAT ENSICAEN CNRS Université de Caen Normandie Université Caen France

We present the experimental and theoretical studies of lattice dynamics, electronic structure, and magnetodielectric relaxation in the ferrimagnetic (FiM) Ni4Nb2O9. This system exhibits a distorted honeycomb lattice with the space group Pbcn (no. 60) and undergoes FiM ordering below 76 K (TFN), accompanied by a magnetic compensation at 33 K (TCOM). By employing density-functional theory (DFT+U) calculations and vibrational spectroscopy, we study all the allowed Raman and infrared phonon modes in Ni4Nb2O9. Temperature-dependent analysis of Raman-active phonon frequencies provides evidence of spin-phonon coupling in Ni4Nb2O9. Interestingly, we observe a nonlinear mode softening phenomenon in both frequencies ω(T) and their linewidths δωF(T), which can be described using three-phonon anharmonic processes. Contrary to the behavior of the remaining modes, 510 cm−1 mode shows a blue shift and effectively acts as a breathing mode for Ni atoms of two sublattices, and hence plays a crucial role in stabilizing the FiM ground state, thus explaining the strong sensitivity of this Ag mode to temperature. Our investigation of the temperature- and field-dependent relative dielectric permittivity and loss-tangent data reveals the absence of magnetodielectric coupling and the presence of dipole relaxation behavior in Ni4Nb2O9. Additionally, the theoretically determined indirect band gap is about 2.7 eV. Overall, our study helps to fill the existing knowledge gap and provides valuable insights into the electronic, vibrational, and magnetodielectric properties of Ni4Nb2O9, shedding light on its potential applications in dielectric-ceramic resonators and electrochemical sensors.

关键词： Local density approximation

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Partial observation can induce mechanistic mismatches in data-constrained models of neural dynamics 24

Partial observation can induce mechanistic mismatches in dat...

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Proceedings of the 38th International Conference on Neural Information Processing Systems

作者： William Qian Jacob A. Zavatone-Veth Benjamin S. Ruben Cengiz Pehlevan Biophysics Graduate Program and Kempner Institute for the Study of Natural and Artificial Intelligence Harvard University Cambridge MA John A. Paulson School of Engineering and Applied Sciences and Center for Brain Science Harvard University and Department of Physics Harvard University Cambridge MA Biophysics Graduate Program Harvard University Cambridge MA Kempner Institute for the Study of Natural and Artificial Intelligence and John A. Paulson School of Engineering and Applied Sciences and Center for Brain Science Harvard University Cambridge MA

ISBN: (纸本)9798331314385

One of the central goals of neuroscience is to gain a mechanistic understanding of how the dynamics of neural circuits give rise to their observed function. A popular approach towards this end is to train recurrent neural networks (RNNs) to reproduce experimental recordings of neural activity. These trained RNNs are then treated as surrogate models of biological neural circuits, whose properties can be dissected via dynamical systems analysis. How reliable are the mechanistic insights derived from this procedure? While recent advances in population-level recording technologies have allowed simultaneous recording of up to tens of thousands of neurons, this represents only a tiny fraction of most cortical circuits. Here we show that observing only a subset of neurons in a circuit can create mechanistic mismatches between a simulated teacher network and a data-constrained student, even when the two networks have matching single-unit dynamics. In particular, partial observation of models of low-dimensional cortical dynamics based on functionally feedforward or low-rank connectivity can lead to surrogate models with spurious attractor structure. Our results illustrate the challenges inherent in accurately uncovering neural mechanisms from single-trial data, and suggest the need for new methods of validating data-constrained models for neural dynamics.

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Concurrent weak localization and double Schottky barrier across a grain boundary in bicrystal SrTiO3

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Physical Review B 2023年第10期107卷 104401-104401页

作者： M. Egilmez S. El-Khatib F. Mustafa S. Ahmad A. Di Bernardo J. W. A. Robinson Department of Physics American University of Sharjah Sharjah PO Box 26666 United Arab Emirates Materials Science and Engineering Program American University of Sharjah Sharjah PO Box 26666 United Arab Emirates Department of Physics University of Konstanz 78457 Konstanz Germany Department of Materials Science & Metallurgy University of Cambridge Cambridge CB3 0FS United Kingdom

Stoichiometric SrTiO3 (STO) is a wide band-gap insulator in which oxygen deficiency generates a low-temperature metallic ferromagnetic state. Here, we report weak ferromagnetic-like and metallic transport in oxygen-deficient bicrystal of STO with a low-temperature electron mobility and surface carrier density of 2800cm2V−1s−1 and 3.500×1016cm−2, respectively. Moreover, we show that magnetotransport behavior in the bulk and across the grain boundary (GB) in STO single crystals are significantly different. In the bulk, our magnetotransport results agree with those reported in the literature. Importantly, low-temperature magnetotransport across the GB shows a disorder-induced metal-insulator transition, and it is modeled as a quasi–two-dimensional system below 10 K that accounts for weak localization (WL), supported by electron-electron, electron-phonon, and Hikami-Larkin-Nagaoka (HLN) quantum interference models. The HLN model accounts for realistic length scales: the dephasing length Lϕ, and the spin-orbit (SO) scattering length LSO, which are comparable to the electron mean-free path, resembling the surface-conducting nature across the GB. Our experimental work shows the importance of structural defects in the interpretation of magnetotransport in SrTiO3 and shows that WL is concurrent with a double Schottky barrier at the GB interface.

关键词： Charge Electrical conductivity Localization Magnetic interactions Magnetism

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Measurement of Myopia and Normal Human Choroidal Thickness Using Spectral Domain Optical Coherence Tomography

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MCB Molecular and Cellular Biomechanics 2022年第3期19卷 151-157页

作者： Qin, Jia An, Lin Innovation and Entrepreneurship Teams Project of Guangdong Provincial Pearl River Talents Program Guangdong Weiren Meditech Co. Ltd. Foshan528000 China School of Medical Imaging Weifang Medical University Weifang261053 China School of Physics and Optoelectronic Engineering Foshan University Foshan528225 China Co. Ltd. Foshan528200 China Co. Ltd. Foshan528200 China

Myopia is a common ophthalmic deficiency. The structure and function of choroid layer is assumed to be associated with myopia. In this study, a laboratory developed spectral domain optical coherence tomography scanning system is used to image human eyes. The axial resolution of the system is about 7 μm, and the acquisition rate is 100 kHz. Firstly, a cross-sectional image was acquired by averaging 100 images from imaging posterior segment of each eye. The choroid thickness was measured by 11 discrete points. The average thickness of normal human eyes was (0.296 ± 0.126) mm, whereas the average choroid thickness of myopic eyes was (0.220 ± 0.095) mm. Afterwards, the T test is used to calculate the data statistically. The analysis of the final result is based on the average thickness measured and the thickness of each measuring point. There was a significant difference in choroid thickness between myopia and normal eyes (P value © 2022 Tech Science Press. All rights reserved.

关键词： Diagnosis

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Utilization of Cu-Foil Waste as a High-Capacity Anode Material for High Performance LiNi0.8Co0.1Mn0.1O2/CuO@Graphite Batteries

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Defect and Diffusion Forum 2022年 417卷 207-217页

作者： Ikhsanudin, Muhammad Nur Arinawati, Meidiana Nursukatmo, Hartoto Nilasary, Hanida Oktaviano, Haryo Satriya Muzayanha, Soraya Ulfa Jamaluddin, Anif Centre of Excellence for Electrical Energy Storage Universitas Sebelas Maret Surakarta57146 Indonesia Department of Chemical Engineering Universitas Sebelas Maret Jl. Ir. Sutarmi 36A Surakarta57126 Indonesia Physics Education Program Universitas Sebelas Maret Jl. Ir. Sutarmi 36A Surakarta57126 Indonesia Jl. Mega Kuningan Barat III Jakarta Selatan12950 Indonesia

Significant demand for Li-ion batteries (LIBs) raises awareness of future LIBs wastes being reprocessed, reused, or recycled. In this research, copper foil waste from spent LIBs is upcycled as an anode material, CuO. The hydrometallurgical route was applied to selectively dissolve copper foils where nitric acid, maleic acid, and acetic acid were used as the leaching agents while oxalic acid was used to precipitate copper into copper oxalate, which is a precursor to CuO. CuO was obtained by calcination of copper oxalate at high temperatures. Based on XRD and FTIR analysis, Copper (II) oxalate dihydrwerees are successfully obtained, while SEM images of the samples confirmed micron-sized agglomerates consisting of submicron primary particles. XRD analysis of CuO samples obtained from various leaching processes confirmed that a pure CuO is successfully synthesized from the nitric acid leaching process while CuO from acetic acid and maleic acid leaching has Cu2O and Cu phases. CuO and 10%CuO@graphite sample from nitric acid leaching were used as sole anode and composite anode in a LiNi0.8Co0.1Mn0.1O2(NCM) battery, respectively. The initial columbic efficiency of CuO anode was far inferior to CuO@graphite. However, CuO@graphite had a higher specific charge-discharge capacity with a value of 347.8 mAh/g compared to pure graphite (286.5 mAh/g). In conclusion, Cu-foils are a promising source of CuO to enhance the capacity of commercial graphite anode. © 2022 Trans Tech Publications Ltd, Switzerland.

关键词： Lithium-ion batteries

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Strain-tuning of domain walls in multilayer graphene probed in the quantum Hall regime

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Physical Review B 2022年第8期105卷 L081408-L081408页

作者： Paul Anderson Yifan Huang Yuanjun Fan Sara Qubbaj Sinisa Coh Qin Zhou Claudia Ojeda-Aristizabal Department of Physics and Astronomy California State University Long Beach Long Beach California 90840 USA Department of Mechanical and Materials Engineering University of Nebraska Lincoln Nebraska 68588-0526 USA Department of Mechanical Engineering and Materials Science and Engineering Program University of California Riverside Riverside California 92521 USA

Domain walls, topological defects that define the frontier between regions of different stacking order in multilayer graphene, have proved to host exciting physics. The ability to tune these topological defects in situ in an electronic transport experiment brings a wealth of possibilities in terms of fundamental understanding of domain walls as well as for electronic applications. Here, we demonstrate, through a MEMS (microelectromechanical system) actuator and magnetoresistance measurements, the effect of domain walls in multilayer graphene quantum Hall effect. Reversible and controlled uniaxial strain triggers the topological defects, manifested as addtional quantum Hall effect plateaus as well as a discrete and reversible modulation of the current across the device. Our findings are supported by theoretical calculations and constitute indication of the in situ tuning of topological defects in multilayer graphene probed through electronic transport, opening the way for the use of reversible topological defects in electronic applications.

关键词： Domain walls Transport phenomena Graphene Resistivity measurements Tight-binding model

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Discovery of Ni Activated Sintering of MoNbTaW Predicted by a Computed Grain Boundary Diagram

SSRN

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SSRN 2023年

作者： Shivakumar, Sashank Song, Keqi Wang, Chunyang Lei, Tianjiao Xin, Huolin L. Rupert, Timothy J. Luo, Jian Department of Nano and Chemical Engineering Program of Materials Science and Engineering University of California San Diego La Jolla CA92093 United States Department of Physics and Astronomy University of California IrvineCA92697 United States Department of Materials Science and Engineering Department of Mechanical and Aerospace Engineering University of California IrvineCA92697 United States

Activated sintering of refractory metals represents a classical phenomenon in powder metallurgy. This study discovers that Ni addition can enhance sintering of MoNbTaW both above and below the bulk solidus composition at 1800 °C, thereby demonstrating the first example of activated sintering of a high-entropy alloy. To probe the underlying mechanism, experiments reveal complete grain boundary (GB) wetting above the bulk solidus composition, which logically infers the stabilization of a liquid-like interfacial phase (GB complexion) in a prewetting region below the bulk solidus composition. Furthermore, bulk CALPHAD (calculation of phase diagram) methods have been extended to model GBs in Ni-doped MoNbTaW to compute a GB "phase" diagram to forecast high-temperature GB disordering in the prewetting region and rationalize the observed Ni activated sintering of MoNbTaW. Only weak GB segregation of Ni is found in furnace-cooled specimens, which suggests GB "drying" during cooling, consistent with the observed nanoscale precipitates along GBs. © 2023, The Authors. All rights reserved.

关键词： Grain boundaries

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Longitudinal, Multimodal Tracking Reveals Lasting Neurovascular Impact of Individual Microinfarcts

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Advanced Science 2025年第0期12卷 e2417003页

作者： Jin, Yifu He, Fei Rathore, Haad Sun, Yingchu Zhang, Jia-ao Li, Xinyu Yin, Rongkang Zhu, Hanlin Xie, Chong Luan, Lan Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States Neuroengineering Initiative Rice University HoustonTX77005 United States Applied Physics Program Rice University HoustonTX77005 United States Department of Bioengineering Rice University HoustonTX77005 United States

Microinfarcts, the "invisible lesions", are prevalent in aged and injured brains and associated with cognitive impairments, yet their neurophysiological impact remains largely unknown. Using a multimodal chronic neural platform that combines functional microvasculature imaging with spatially resolved neural recording, the neurovascular effect of a single microinfarct is investigated. Unlike larger strokes, microinfarcts induced only temporary suppression of neural activity with minimal cell death, with recovery paralleling vasculature remodeling at the infarct core. Neural activity is more severely suppressed at the shallower cortical layer despite milder vascular damage compared to deeper layers, and the excitability of fast-spiking interneurons attenuation is accompanied by heightened bursting of regular spiking neurons. Spike phase locking at the low-gamma band is disrupted, indicating a lasting impairment of long-range assembly communication. These results highlight the subtle yet significant neurovascular disruptions of a single microinfarct. © 2025 The Author(s). Advanced Science published by Wiley-VCH GmbH.

关键词： Flexible electronics

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Bovine bone–based activated carbon composite containing nanomagnetite as a catalyst for photo-Fenton reactions

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Environmental Science and Pollution Research 2025年 1-18页

作者： Guidolin, Thays de Oliveira Polla, Mariana Borges Rodriguez, Adriane de Assis Lawisch Wermuth, Tiago Bender Eller, Sarah de Oliveira, Tiago Franco Pereira, Fabiano Raupp da Cas Viegas, Alexandre Montedo, Oscar Rubem Klegues Cechinel, Maria Alice Prado Arcaro, Sabrina Universidade Do Extremo Sul Catarinense SC CriciúmaCEP 88806-000 Brazil Laboratório de Engenharia Ambiental Universidade de Santa Cruz Do Sul RS Santa Cruz Do SulCEP 96815-900 Brazil Graduate Program in Health Sciences Federal University of Health Sciences of Porto Alegre RS Porto AlegreCED 90050-170 Brazil Institute of Physics Federal University of Rio Grande Do Sul 9500 RS Porto AlegreCEP 91501-970 Brazil Department of Chemical and Food Engineering Federal University of Santa Catarina SC FlorianópolisCEP 88040-900 Brazil

Magnetic composites (MC) prepared from magnetite nanoparticles (MNP) and activated carbon from bovine bone (AC) in different proportions (75/25, 50/50, and 25/75) were used as catalysts in the photo-Fenton process to degrade methylene blue (MB) in aqueous solution. The materials were prepared by the citrate–nitrate sol–gel synthesis method and used as catalysts in the photo-Fenton process. The photocatalytic tests were performed in a cylindrical reactor with a 4.13-cm internal diameter and 300-mL maximum capacity, equipped with 9.9-W visible light lamps. The specific surface area of the MC increased by up to 1138.39% with the addition of AC. Morphological analysis confirmed the anchoring of MNPs on the AC surface. The band gap values of the materials ranged from 1.16 to 1.55 eV and increased proportionally with the addition of AC to the MC compositions. MC-75/25 and MC-50/50 presented predominantly superparamagnetic behavior, while for MC-25/75 superparamagnetic and superimposed paramagnetic phases were observed. All samples showed good reduction of the MB concentration, exceeding 80% after 10 cycles of use. The mineralization advanced extensively to simple organic acids, proving the non-generation of harmful by-products and the efficiency of this photocatalytic system. The use of magnetic composites favored the efficient separation of the catalyst without causing secondary pollution, in addition to increasing the stability and reusability of the catalysts. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.

关键词： Bone

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