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arXiv 2024年

作者： Liu, Zhuoyi Grigas, Alex T. Sumner, Jacob Knab, Edward Davis, Caitlin M. O’Hern, Corey S. Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States Department of Chemistry Yale University New HavenCT06520 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States

Proteins naturally occur in crowded cellular environments and interact with other proteins, nucleic acids, and organelles. Since most previous experimental protein structure determination techniques require that proteins occur in idealized, non-physiological environments, the effects of realistic cellular environments on protein structure are largely unexplored. Recently, Förster resonance energy transfer (FRET) has been shown to be an effective experimental method for investigating protein structure in vivo. Inter-residue distances measured in vivo can be incorporated as restraints in molecular dynamics (MD) simulations to model protein structural dynamics in vivo. Since most FRET studies only obtain inter-residue separations for a small number of amino acid pairs, it is important to determine the minimum number of restraints in the MD simulations that are required to achieve a given root-mean-square deviation (RMSD) from the experimental structural ensemble. Further, what is the optimal method for selecting these inter-residue restraints? Here, we implement several methods for selecting the most important FRET pairs and determine the number of pairs Nr that are needed to induce conformational changes in proteins between two experimentally determined structures. We find that enforcing only a small fraction of restraints, Nr/N 0.08, where N is the number of amino acids, can induce the conformational changes. These results establish the efficacy of FRET-assisted MD simulations for atomic scale structural modeling of proteins in vivo. © 2024, CC BY.

关键词： Conformations

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Effect of feedback on learning motivation of primary teacher education students in primary school physics courses 10

Effect of feedback on learning motivation of primary teacher...

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10th National physics Seminar, SNF 2021

作者： Sianipar, L.K. Sitompul, H. Sanjaya, L.A. Puspa, R.W.D. Pertiwi, W.A. Qoiriyah, W. Department of Physics Education Universitas Pelita Harapan Tangerang15811 Indonesia Department of Physics Faculty of Mathematics and Natural Science Universitas Negeri Jakarta Indonesia Kartika VIII-1 Senior High School Jakarta Indonesia Islamic Education Management Study Program Faculty Islamic of Education and Teacher Training Muhammad Azim Institute Jambi Indonesia Informatics Engineering Study Program Faculty of Engineering Sheikh Yusuf Islamic University Tangerang Indonesia

Based on the results of the questionnaire distributed to Primary Teacher Education Students, 96% of students said that physics is difficult to understand because the material is very complex, many formulas, especially the learning process is done online. This study aims to describe the influence of providing feedback on the motivation of Primary Teacher Education Students in primary school physics courses. The method used in this research is descriptive qualitative. Meanwhile, the instrument used was a questionnaire which was distributed to 115 elementary school education students. The result of the research shows that giving feedback consistently is able to motivate students. This can be seen from the results of the questionnaires distributed, each indicator is of very good value. © 2021 Institute of physics Publishing. All rights reserved.

关键词： Students

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Design of Mixed-Dimensional QDs/MoS2/TiO2 Heterostructured Resistive Random-Access Memory with Interfacial Analog Switching Characteristics for Potential Neuromorphic Computing

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ACS Applied Electronic Materials 2024年第3期6卷 1581-1589页

作者： Tang, Shin-Yi Shih, Yu-Chuan Shen, Ying-Chun Cyu, Ruei-Hong Chen, Chieh-Ting Yang, Tzu-Yi Chaudhary, Mayur Peng, Yu-Ren Kuo, Yao-Ren Miao, Wen-Chien Yu, Yi-Jen Lee, Ling Kuo, Hao-Chung Chueh, Yu-Lun Department of Materials Science and Engineering National Tsing Hua University Hsinchu30013 Taiwan College of Semiconductor Research National Tsing Hua University Hsinchu30013 Taiwan Semiconductor Research Center Hon Hai Research Institute Taipei11492 Taiwan Ph. D. Program in Prospective Functional Materials Industry National Tsing Hua University Hsinchu30013 Taiwan Department of Electrophysics College of Science National Yang Ming Chiao Tung University Hsinchu30010 Taiwan Instrument Center National Tsing Hua University Hsinchu30013 Taiwan Department of Photonics Institute of Electro-Optical Engineering National Yang-Ming Chiao Tung University Hsinchu30010 Taiwan Department of Physics National Sun Yat-Sen University Kaohsiung80424 Taiwan Department of Materials Science and Engineering Korea University Seoul02841 Korea Republic of

Resistive random-access memory (RRAM) is one of the most promising candidates for next-generation nanoscale nonvolatile memory devices and neuromorphic computing applications. In this study, we developed a novel mixed-dimensional design for RRAM devices, incorporating zero-dimensional quantum dots (QDs), two-dimensional MoS2, and a TiO2 switching layer to achieve prominent interfacial switching behaviors. Compared with typical filamentary RRAM devices, the proposed heterostructure featured a light-sensitive QDs/MoS2 layer that allowed for bias-controllable resistive changes during the set and reset processes without abrupt switching. This was endowed by effective electron-hole pair separations upon excitation and the generation of a thin molybdenum oxide (MoOx) layer due to the accumulation of oxygen ions at the interface between MoS2 and TiO2. The ITO/QDs/MoS2/TiO2/Pt RRAM device exhibited an on/off ratio of 10 with improved endurance under 515 nm laser illumination and wavelength-dependent resistive switching behavior, making it useful for multilevel storage. Furthermore, the heterostructured device demonstrated synaptic characteristics with enhanced potentiation and depression nonlinearities and asymmetry factors, revealing its potential for future neuromorphic applications. © 2024 American Chemical Society.

关键词： Titanium dioxide

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Optical spectroscopy of excitons in ReS2 monolayers grown by chemical vapor deposition

arXiv

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arXiv 2024年

作者： Ojo, Solomon Onasanya, Juwon Benamara, Morad Hamad, Bothina Manasreh, M.O. Material Science and Engineering program University of Arkansas FayettevilleAR72701 United States Institute of nanotechnology University of Arkansas FayettevilleAR72701 United States Physics Department University of Arkansas FayettevilleAR72701 United States Department of Electrical Engineering and Computer Science University of Arkansas FayettevilleAR72701 United States

Monolayers of ReS2 were grown by a chemical vapor deposition technique on SiO2/Si substrates and investigated at room temperature by using μ-Raman, μ-photoluminescence (PL) and absorbance spectroscopies. The Raman scattering spectrum exhibits several phonon modes that were confirmed by the computation analysis based on the density functional theory. The ReS2 structural integrity was confirmed by using the XRD and the energy dispersion spectroscopy that was obtained by the scanning electron microscopy. Photoluminescence spectra show excitons related to interband transition in thin monolayer flakes and bulk-like structures. Additionally, a sharp PL line located at 1.2620 eV with a second harmonic peak at 2.5420 eV were observed and explained in terms of interband excitonic transitions originated within the rhenium 5d orbit. An optical absorbance spectrum with an exciton peak around 1.4660 eV was obtained for an assembly of ReS2 flakes grown on silica substrate. Copyright © 2024, The Authors. All rights reserved.

关键词： Scanning electron microscopy

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Electric field tunable layer polarization in graphene/boron-nitride twisted quadrilayer superlattices

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Physical Review B 2022年第20期106卷 205134-205134页

作者： Ziyan Zhu Stephen Carr Qiong Ma Efthimios Kaxiras Department of Physics Harvard University Cambridge Massachusetts 02138 USA Brown Theoretical Physics Center and Department of Physics Brown University Providence Rhode Island 02912 USA Department of Physics Boston College Chestnut Hill Massachusetts 02467 USA CIFAR Azrieli Global Scholars program CIFAR Toronto Canada John A. Paulson School of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 USA

The recently observed unconventional ferroelectricity in AB bilayer graphene sandwiched by hexagonal boron nitride (hBN) presents a new platform to manipulate correlated phases in multilayered van der Waals heterostructures [Zheng et al., Nature 588, 71 (2020).]. We present a low-energy continuum model for AB bilayer graphene encapsulated by the top and bottom layers of either hBN or graphene, with two independent twist angles. For the graphene/hBN heterostructures, we show that twist angle asymmetry leads to a layer polarization of the valence and conduction bands. We also show that an out-of-plane displacement field not only tunes the layer polarization but also flattens the low-energy bands. We extend the model to show that the electronic structures of quadrilayer graphene heterostructure consisting of AB bilayer graphene encapsulated by the top and bottom graphene layers can similarly be tuned by an external electric field.

关键词： Electronic structure 2-dimensional systems

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The Effect of Data Augmentation on the Accuracy of Fish Species Classification Using Deep Learning

The Effect of Data Augmentation on the Accuracy of Fish Spec...

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International Conference on Informatics and Computing (ICIC)

作者： Ellya Helmud Catur Edi Widodo Oky Dwi Nurhayati Doctor Information System Postgraduate Diponegoro University Semarang Indonesia Faculty of Information Technology Information Systems Study Program Atma Luhur Institute of Science and Business Pangkalpinang Indonesia Physics Department Faculty of Science and Mathematics Diponegoro University Semarang Indonesia Department of Computer Engineering Faculty of Engineering Diponegoro University Semarang Indonesia

ISBN: (数字)9798331517601

ISBN: (纸本)9798331517618

Fish image classification presents an intriguing challenge in the field of computer vision. This research aims to develop an accurate classification model to differentiate between four different fish species using a convolutional neural network. The dataset used consists of $\mathbf{3 0 1 0}$ fish images, divided into training, validation, and testing sets. The convolutional neural network model was trained both with and without data augmentation. Evaluation results show that the model trained with data augmentation achieved an accuracy of $95 \%$ with a loss value of 0.0983, slightly better than the model without augmentation which achieved an accuracy of $94.56 \%$ with a loss value of $\mathbf{0. 1 7 9 4}$. This indicates that data augmentation techniques are effective in improving model performance, likely because augmentation helps the model generalize better to variations in fish image data. The results of this research demonstrate the significant potential of convolutional neural network for fish image classification tasks. The developed model can serve as a foundation for the development of computer vision-based applications such as automatic fish species identification in fisheries or educational applications. Further research can be conducted by exploring different convolutional neural network architectures, more advanced data augmentation techniques, and larger datasets to improve model performance.

关键词： Deep learning Training Accuracy Computational modeling Computer architecture Fish Data augmentation Data models Convolutional neural networks Image classification

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Surface Second Harmonic Generation from Topological Dirac Semimetal PdTe2

arXiv

引用

arXiv 2023年

作者： Faizanuddin, Syed Mohammed Chien, Ching-Hang Chan, Yao-Jui Kuo, Chia-Nung Lue, Chin Shuan Wen, Yu-Chieh Institute of Physics Academia Sinica Taipei11529 Taiwan Nano Science and Technology Program Taiwan International Graduate Program Academia Sinica Taipei11529 Taiwan Department of Engineering and System Science National Tsing Hua University Hsinchu300044 Taiwan Department of Physics National Cheng Kung University Tainan701401 Taiwan Research Center for Applied Sciences Academia Sinica Taipei11529 Taiwan

Three-dimensional topological semimetals were shown to host anomalously strong optical nonlinearity, but yet whether such enhancement can occur at their surfaces via topological boundary states remains an open question. Here we tackle this question by examining polarization-dependent rotational-anisotropy optical second harmonic generation (SHG) from transition metal dichalcogenide Dirac semimetal PdTe2. We find its reflected SHG to follow C3v surface symmetry with a time-varying intensity dictated by oxidation kinetics of the material after its surface cleavage, confirming the surface-derived origin of SHG. The complex surface nonlinear optical susceptibility tensor is fully characterized by heterodyne interferometry, unveiling a hidden giant out-of-plane response χzzz (2) (> 10.6 nm2/V or, equivalently, an effective bulk nonlinear susceptibility > 10.3 nm/V). Our results highlight the topological surfaces/interfaces as a new route toward nonlinear optical applications with released symmetry constraints, and demonstrate SHG as a viable means for in situ probing of surface chemistry of topological systems. Copyright © 2023, The Authors. All rights reserved.

关键词： Nonlinear optics

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Strong light-matter coupling in topological metasurfaces integrated with transition metal dichalcogenides 6

Strong light-matter coupling in topological metasurfaces int...

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6th International Conference on Metamaterials and Nanophotonics, METANANO 2021

作者： Sinev, Ivan Li, Mengyao Benimetskiy, Fedor Ivanova, Tatiana Kiriushechkina, Svetlana Vakulenko, Anton Guddala, Sriram Krizhanovskii, Dmitry Samusev, Anton Khanikaev, Alexander Department of Physics and Engineering ITMO University St. Petersburg Russia Department of Electrical Engineering City College of New York New YorkNY United States Physics Department City College of New York New YorkNY United States Physics Program Graduate Center of the City University of New York New YorkNY United States Department of Physics and Astronomy University of Sheffield SheffieldS3 7RH United Kingdom

Strong light-matter interactions enable unique nonlinear and quantum phenomena at moderate light intensities. Within the last years, polaritonic metasurfaces emerged as a viable candidate for realization of such regimes. In particular, planar photonic structures integrated with 2D excitonic materials, such as transition metal dichalcogenides (TMD), can support exciton polaritons – half-light half-matter quasiparticles. Here, we explore topological exciton polaritons which are formed in a suitably engineered all-dielectric topological photonic metasurface coupled to TMD monolayers. We experimentally demonstrate the transition of topological charge from photonic to polaritonic bands with the onset of strong coupling regime and confirm the presence of one-way spin-polarized edge topological polaritons. The proposed system constitutes a promising platform for photonic/solid-state interfaces for valleytronics and spintronics. © 2021 Institute of physics Publishing. All rights reserved.

关键词： Transition metals

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Advanced Under-Rails Fiber-Optic Sensor for Detection of Rolling Stock and Axles in Tram Transport

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IEEE Transactions on Instrumentation and Measurement 2025年 74卷

作者： Fajkus, Marcel Jargus, Jan Nedoma, Jan Kepak, Stanislav Krizan, Daniel Cubik, Jakub Krenzelok, Tomas Leal, Arnaldo Marques, Carlos VSB—Technical University of Ostrava Faculty of Electrical Engineering and Computer Science Department of Telecommunications Ostrava708 00 Czech Republic Prodin a.s. Pardubice530 02 Czech Republic Graduate Program in Electrical Engineering Federal University of Espirito Santo Vitoria29075-910 Brazil University of Aveiro CICECO—Aveiro Institute of Materials Physics Department Aveiro3810-193 Portugal VSB—Technical University of Ostrava Department of Physics Ostrava708 00 Czech Republic

This article describes the implementation of an advanced fiber-optic intensity sensor for the comprehensive detection of axles and bogies of rail vehicles in tram transport. The sensor uses the principle of optical fiber bending, where the intensity of transmitted light is modulated due to mechanical stress on the fiber caused by the passage of a tram and the subsequent reversible deformation of the rail. The innovative design of the sensor allows for its easy installation under the rail foot, between the rail and the sleeper, replacing conventional anti-vibration pads, and includes specially designed deformable elements which the optical fiber bends and modulates the transmitted light intensity. During long-term testing (11 months in various weather conditions) conducted in the real tram depot (Ostrava, Czech Republic), 20602 tram passages were secured and analyzed. The sensor demonstrated success in detecting bogies, achieving 100% accuracy with no false positives (FPs) or false negatives (FNs). Axle detection showed an average success rate of 86.1%, with variability among different tram types up to 97.8%. The signal modulation was also subjected to detailed analysis, revealing differences in responses between various tram types, which can be attributed to differences in bogie construction and vehicle weight. Due to its electromagnetic immunity, the implemented fiber-optic sensor offers the potential for more reliable detection and broad application possibilities, including track occupancy monitoring, speed measurement, or determining the direction of travel on single-track lines. With slight optimization, the sensor could also be used to weigh rail vehicles or as an axle counter in railway or light rail transport. © 1963-2012 IEEE.

关键词： Bogies (railroad rolling stock)

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Optical Spectroscopy of Excitons in ReS2 Monolayers Grown by Chemical Vapor Deposition

SSRN

引用

SSRN 2024年

作者： Ojo, Solomon Onasanya, Juwon Benamara, Mourad Hamad, Bothina Manasreh, M.O. Material Science and Engineering program University of Arkansas FayettevilleAR72701 United States Institute of nanotechnology University of Arkansas FayettevilleAR72701 United States Physics Department University of Arkansas FayettevilleAR72701 United States Department of Electrical Engineering and Computer Science University of Arkansas FayettevilleAR72701 United States

Monolayers of ReS2 were grown by a chemical vapor deposition technique on SiO2/Si substrates and investigated at room temperature by using μ-Raman, μ-photoluminescence (PL) and absorbance spectroscopies. The Raman scattering spectrum exhibits several phonon modes that were confirmed by the computation analysis based on the density functional theory. The ReS2 structural integrity was confirmed by using the XRD and the energy dispersion spectroscopy that was obtained by the scanning electron microscopy. Photoluminescence spectra show excitons related to interband transition in thin monolayer flakes and bulk-like structures. Additionally, a sharp PL line located at 1.2620 eV with a second harmonic peak at 2.5420 eV was observed and explained in terms of interband excitonic transitions originating within the rhenium 5d orbit. An optical absorbance spectrum with an exciton peak around 1.4660 eV was obtained for an assembly of ReS2 flakes grown on silica substrate. © 2024, The Authors. All rights reserved.

关键词： Phonons

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