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SSRN 2024年

作者： Al-Hunaiti, Afnan Bakri, Zaid Li, Xinyang Duan, Lian Al-Abdallat, Asal Alastuey, Andres Viana, Mar Arar, Sharif Petäjä, Tuukka Hussein, Tareq Department of Chemistry School of Science University of Jordan Amman11942 Jordan Department of Chemistry and Materials Science School of Chemical Engineering Nanochemistry and Nanoengineering Aalto University Aalto00076 Finland Department of Physics and Atmospheric Sciences Program Michigan Technological University HoughtonMI49931 United States UHELFI- Helsinki00014 Finland Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention Department of Environmental Science & Engineering Fudan University Shanghai200438 China Department of Physics School of Science University of Jordan Amman11942 Jordan Barcelona08034 Spain

The Eastern Mediterranean is a unique region for air pollution because it is the crossroads between three continents exchanging air pollution. Here, we investigated urban particulate matter (PM) carbonaceous and water-soluble ions in Amman, Jordan. The PM2.5 total carbon (TC) annual mean was 7.6±3.6 µg/m3 (organic carbon (OC) 5.9±2.8 µg/m3 and elemental carbon (EC) 1.7±1.1 µg/m3), which was about 16.3% of the PM2.5. The PM10 TC annual mean was 8.4±3.9 µg/m3 (OC 6.5 ± 3.1 µg/m3 and elemental carbon (EC) 11.9±1.1µg/m3), about 13.3% of the PM10. The PM2.5 total water-soluble ions annual mean was 7.9±1.9 µg/m3 (about 16.9%), and that of the PM10 was 10.1±2.8 µg/m3 (about 16.0%). The minor ions (F-, NO2-, Br-, and PO43-) constituted less than 1% in the PM fractions. The significant fraction was for SO42- (PM2.5 4.7±1.6 µg/m3 (10.0%) and PM10 5.3±1.9 µg/m3 (8.3%)). The NH4+ had higher amounts of PM2.5 (1.3±0.6 µg/m3;2.7%) than that PM10 (0.9±0.4 µg/m3;1.4%). During sand and dust storm (SDS) events, TC, Cl-, and NO3- were doubled in PM, SO42- did not increase significantly, and NH4+ slightly decreased. Regression analysis revealed: (1) carbonaceous aerosols come equally from primary and secondary sources, (2) about 50% of the OC came from non-combustion sources, (3) traffic emissions dominate the PM, (4) agricultural sources have a negligible effect, (5) SO42- is completely neutralized by NH4+ in the PM2.5 but there could be additional reactions involved in the PM10, and (6) (NH4)2SO4, was the major species formed by SO42-and NH4+ instead of NH4HSO4. © 2024, The Authors. All rights reserved.

关键词： Ions

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Unnecessary risks created by uncontrolled rocket reentries

arXiv

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arXiv 2022年

作者： Byers, Michael Wright, Ewan Boley, Aaron Byers, Cameron Department of Political Science University of British Columbia VancouverBC Canada Interdisciplinary Studies Graduate Program University of British Columbia VancouverBC Canada Department of Physics and Astronomy University of British Columbia VancouverBC Canada Bachelor of Engineering Program University of Victoria VictoriaBC Canada

In 2020, over 60% of launches to low Earth orbit resulted in one or more rocket bodies being abandoned in orbit and eventually returning to Earth in an uncontrolled manner. When they do so, between 20 and 40% of their mass survives the heat of atmospheric reentry. Many of the surviving pieces are heavy enough to pose serious risks to people, on land, at sea, and in airplanes. There is no international consensus on the acceptable level of risk from reentering space objects. This is sometimes a point of contention, such as when a 20 tonne Long March 5B core stage made an uncontrolled reentry in May 2021. Some regulators, including the US, France, and ESA, have implemented a 1 in 10, 000 acceptable casualty risk (i.e., statistical threat to human life) threshold from reentering space objects. We argue that this threshold ignores the cumulative effect of the rapidly increasing number of rocket launches. It also fails to address low risk, high consequence outcomes, such as a rocket stage crashing into a high-density city or a large passenger aircraft. In the latter case, even a small piece could cause hundreds of casualties. Compounding this, the threshold is frequently ignored or waived when the costs of adherence are deemed excessive. We analyse the rocket bodies that reentered the atmosphere from 1992-2021 and model the associated cumulative casualty expectation. We then extrapolate this trend into the near future (2022-2032), modelling the potential risk to the global population from uncontrolled rocket body reentries. We also analyse the population of rocket bodies that are currently in orbit and expected to deorbit soon, and find that the risk distribution is significantly weighted to latitudes close to the equator. This represents a disproportionate burden of casualty risk imposed on the countries of the Global South by major spacefaring countries. Modern rockets have reignitable engines, allowing controlled reentries into remote areas of the oceans. This, combine

关键词： Rockets

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Optical Imaging of Flavor Order in Flat Band Graphene

arXiv

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arXiv 2024年

作者： Xie, Tian Wolf, Tobias M. Xu, Siyuan Cui, Zhiyuan Xiong, Richen Ou, Yunbo Hays, Patrick Holleis, Ludwig F. Guo, Yi Sheekey, Owen I. Patterson, Caitlin Arp, Trevor Watanabe, Kenji Taniguchi, Takashi Tongay, Seth Ariel Young, Andrea F. MacDonald, Allan H. Jin, Chenhao Department of Physics University of California at Santa Barbara Santa BarbaraCA93116 United States Department of Physics University of Texas at Austin AustinTX78712 United States Materials Science and Engineering Program School of Engineering for Matter Transport and Energy Arizona State University TempeAZ85287 United States Research Center for Electronic and Optical Materials National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Research Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan

Spin- and valley flavor polarization plays a central role in the many-body physics of flat band graphene1–21, with fermi surface reconstructions—often accompanied by quantized anomalous Hall1–8 and superconducting state9–14—observed in a variety of experimental systems. Here we describe an optical technique that sensitively and selectively detects flavor textures via the exciton response of a proximal transition metal dichalcogenide layer. Through a systematic study of rhombohedral and rotationally faulted graphene bilayers and trilayers, we show that when the semiconducting dichalcogenide is in direct contact with the graphene, the exciton response is most sensitive to the large momentum rearrangement of the Fermi surface, providing information that is distinct from and complementary to electrical compressibility measurements. The wide-field imaging capability of optical probes allows us to obtain spatial maps of flavor orders with high throughput, and with broad temperature and device compatibility. Our work paves the way for optical probing and imaging of flavor orders in flat band graphene systems. Copyright © 2024, The Authors. All rights reserved.

关键词： Graphene

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Tunable Optical Beam Focusing Using Static Water Droplets on an Electrospun Polymer Fiber

SSRN

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SSRN 2024年

作者： Budlayan, Marco Laurence M. Palangyos, Dina C. Patricio, Jonathan N. Arco, Susan D. Guerrero, Raphael A. Department of Physics College of Mathematics and Natural Science Caraga State University Butuan City8600 Philippines Department of Physics School of Science and Engineering Ateneo de Manila University Quezon City1108 Philippines Mathematics and Natural Sciences Department College of Computing Pangasinan State University Pangasinan Urdaneta2428 Philippines Materials Science and Engineering Program College of Science University of the Philippines Diliman Quezon City1101 Philippines Institute of Chemistry College of Science University of the Philippines Diliman Quezon City1101 Philippines Ateneo de Manila University Philippines

This work explores the use of static water microdroplets on a microfiber to vary the width of an optical beam. Varying the water droplet volume changes the beam width without replacing any optical components. A surface derived from glass deposited with polyvinyl chloride (PVC) microfibers via electrospinning was used to sustain the droplet shape on the surface. Scanning electron microscopy revealed the presence of randomly intertwined microfibers with diameters of less than 3 µm which afforded the surface a hydrophobic property. A decrease in the optical transmittance of the films and an increase in the water contact angle were also observed as fiber density increases. Results revealed an increase in the beam size with increasing droplet volume manifesting a defocusing or magnifying effect as the beam passed through the droplets. The beam maintained its Gaussian profile, confirming that the presence of the deposited fibers did not significantly alter the beam type. By using droplets with different liquid volumes (5-60 µL), we replicate the action of a convex lens with varying focal length. © 2024, The Authors. All rights reserved.

关键词： Microfibers

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Ti-Nb-Zr Ternary Alloy Coatings Sputter Deposited on Aisi 316l Stainless Steel

SSRN

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SSRN 2023年

作者： Lemos, Lucas L.D. de Castro, Ana Luiza Costa, Sidney C.Z. Mastelaro, Valmor Roberto Nascente, Pedro A.P. Graduate Program in Materials Science and Engineering Federal University of Sao Carlos SP Sao CarlosCEP 13565-905 Brazil Sao Carlos Institute of Physics University of Sao Paulo SP Sao CarlosCEP 13560-590 Brazil Department of Materials Engineering Federal University of Sao Carlos SP Sao CarlosCEP 13565-905 Brazil

Titanium, niobium, and zirconium are non-toxic and non-allergenic biocompatible metals, and the ternary Ti-Nb-Zr bulk alloys having predominantly β phase (body-centered cubic structure) present superior corrosion resistance and biocompatibility than medical grade AISI 316L stainless steel (SS) which is commonly used as metallic prosthetic material. However, the Ti-Nb-Zr alloys are much more costly than SS, so the main goal of this study is to produce and characterize lesser costly Ti-Nb-Zr coatings. Magnetron sputtering has shown to be an adequate technique to coat SS surfaces with Ti-based alloys. Three ternary alloy coatings having approximately the same amount of Zr (12-14 at.%) and different amounts of Ti (76, 62, and 53 at.%) and Nb (10, 26, and 34 at.%) were deposited on AISI 316L SS by magnetron sputtering. Only the β phase was detected and the coating surfaces were oxidized, having a beneficial effect on corrosion resistance and presents lesser cytotoxicity. The elastic moduli were evaluated by nanoindentation tests, and the obtained values were smaller than that for the SS substrate. These findings suggest that the Ti-Nb-Zr ternary alloy coatings have promising characteristics for biomedical applications. © 2023, The Authors. All rights reserved.

关键词： Magnetron sputtering

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Magnetoelectric control of spin helicity and nonreciprocal charge transport in a multiferroic metal

arXiv

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arXiv 2025年

作者： Yamaguchi, Daiki Kitaori, Aki Nagaosa, Naoto Tokura, Yoshinori Department of Applied Physics The University of Tokyo Tokyo113-8656 Japan RIKEN Center for Emergent Matter Science CEMS Wako351-0198 Japan Institute of Engineering Innovation The University of Tokyo Tokyo113-0032 Japan RIKEN Fundamental Quantum Science Program Wako351-0198 Japan Tokyo College The University of Tokyo Tokyo113-8656 Japan

A multiferroic state with both electric polarization (P) and magnetization (M) shows the inherently strong P-M coupling, when P is induced by cycloidal (Néel-wall like) spin modulation. The sign of P is determined by clockwise or counterclockwise rotation of spin, termed the spin helicity. Such a multiferroic state is not limited to magnetic insulators but can be broadly observed in conductors. Here, we report the current-induced magnetoelectric control of the multiferroics in a helimagnetic metal YMn6Sn6 and its detection through nonreciprocal resistivity (NRR). The underlying concept is the coupling of the current with the toroidal moment T~P × M~(q(× x!) × M as well as with the magneto-chirality x! ∙ M, where q(and x! being the unit modulation wave vector and the vector spin chirality, respectively. We furthermore observe an enhancement of NRR by the spin-cluster scattering via x! and its fluctuation. These findings may pave a way to exploration of multiferroic conductors and application of the spin-helicity degree of freedom as a state-variable. © 2025, CC BY-NC-ND.

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Parity-time symmetry breaking enables swarming motility in Caenorhabditis elegans

arXiv

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arXiv 2024年

作者： Basaran, Mustafa Yüce, Tevfik Can Keçebaş, Ali Altın, Baha Yaman, Yusuf Ilker Demir, Esin Kocabaş, Coşkun Özdemir, Şahin K. Kocabaş, Aşkın Department of Physics Koç University Sarıyer Istanbul34450 Turkey Bio-Medical Sciences and Engineering Program Koç University Sarıyer Istanbul34450 Turkey Sciences and Engineering Program Harvard University CambridgeMA02138 United States Department of Engineering Science and Mechanics The Pennsylvania State University University ParkPA16802 United States Department of Materials University of Manchester ManchesterM13 9PL United Kingdom Koç University Surface Science and Technology Center Koç University Sarıyer Istanbul34450 Turkey Koç University Research Center for Translational Medicine Koç University Sarıyer Istanbul34450 Turkey

Nonreciprocal interactions break action-reaction symmetry in systems of interacting bodies. This process inevitably introduces non-Hermitian dynamics which with its hallmark signature called exceptional points (EPs) has been a subject of intense research across different disciplines ranging from photonics to metamaterials. Whether non-Hermiticity and EPs are a fundamental property of nature and if so, how nature utilizes them to gain competitive advantage have remained largely unanswered. Although biological systems feature many examples of non-reciprocal interactions with the potential to drive non-Hermitian dynamics, these are often theoretically overlooked and not experimentally investigated. Here, we demonstrate in an active matter composed of social animal Caenorhabditis elegans and bacteria, non-Hermitian dynamics, and the emergence of EPs owing to the nonreciprocal nature of oxygen sensing, nonequilibrium interfacial current, and bacterial consumption. We observed that when driven through the EP, the system collectively breaks parity-time (PT) symmetry leading to traveling waves and arrested phase separation. We further find that these features enable the collective ability to localize interfaces between broken and exact PT-phases. Remarkably, this ability provides a strong evolutionary advantage to animals living in soil. Altogether our results provide mechanistic insights into the detailed symmetries controlling the collective response of biological systems;answer a long-standing problem;and give an example of the EP-enabled dynamics in a biological system. © 2024, CC BY.

关键词： Dynamics

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Coherent Acoustic Phonons in Bi2Se3 Ultrathin Films Probed by Femtosecond, Optical Pump-Probe Spectroscopy

Coherent Acoustic Phonons in Bi2Se3 Ultrathin Films Probed b...

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CLEO: Fundamental Science, CLEO:FS 2024 - Part of Conference on Lasers and Electro-Optics, CLEO 2024

作者： Cheng, Jing Niherysh, Kiryl A. Francis, Peter Chakraborty, Debamitra Lombardi, Floriana Erts, Donats Prischepa, Serghej L. Laszcz, Adam Komissarov, Ivan V. Sobolewski, Roman Materials Science Graduate Program University of Rochester RochesterNY14627 United States Laboratory for Laser Energetics University of Rochester RochesterNY14623-1299 United States Department of Microtechnology and Nanoscience Chalmers University of Technology Gothenburg Sweden Institute of Chemical Physics University of Latvia Riga Latvia Department of Electrical and Computer Engineering University of Rochester RochesterNY14627 United States Dipartimento di Fisica "E.R. Caianiello" Università degli Studi di Salerno Sa FiscianoI-84084 Italy Lukasiewicz Research Network Institute of Microelectronics and Photonics WarszawaPL-02668 Poland

ISBN: (纸本)9781957171395

The dynamics of coherent acoustic phonons in the Bi2Se3 layered crystal system are investigated. The findings reveal that the frequency evolution of breathing modes with the number of the material quintuple layers and the dispersion relation both can be explained by a modified chain model with a nonuniform coupling force. © Optica Publishing Group 2024, © 2024 The Author(s)

关键词： Ultrathin films

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Lévy Light Cones and Critical Causality in Fractional Multiscale Quantum Ising Models

arXiv

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arXiv 2025年

作者： Lewis, Joshua M. Gong, Zhexuan Carr, Lincoln D. Quantum Engineering Program Colorado School of Mines 1523 Illinois St. GoldenCO80401 United States Department of Physics Colorado School of Mines 1523 Illinois St. GoldenCO80401 United States Department of Applied Mathematics and Statistics Colorado School of Mines 1523 Illinois St. GoldenCO80401 United States

We study causality and criticality in a one-dimensional fractional multiscale transverse-field Ising model, where fractional derivatives generate long range interactions beyond the scope of standard power laws. Such fractional responses are common in classical systems including the anomalous stress–strain behaviour of viscoelastic polymers, Lévy-like contaminant transport in heterogeneous porous media, and the non-Debye dielectric relaxation of glassy dielectrics. Furthermore, these unique interactions can be implemented in current quantum information architectures, with intriguing consequences for the many-body dynamics. Using a truncated Jordan-Wigner approach, we show that in the long wavelength limit of the mean field, the dynamical critical exponent is set by the fractional order q as z = q/2. To probe genuine many-body dynamics, we apply matrix-product-state simulations with the time-dependent variational principle adapted to nonlocal couplings. Tracking the entanglement-entropy light cone and performing finite-size scaling of the many-body gap for 0 1/z and classical Lévy flights whose mean-square displacement grows as t2/q provides a direct physical link between fractional interactions and Lévy statistics. Fractional derivatives therefore offer a unified framework in which short-range, power-law, and frustrated long-range interactions emerge as limiting cases, enabling controlled exploration of nonlocal causality bounds and exotic entanglement dynamics within current quantum information platforms. © 2025, CC BY.

关键词： Quantum entanglement

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WISH:wavefront imaging sensor with high resolution

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Light(Science & Applications) 2019年第1期8卷 818-827页

作者： Yicheng Wu Manoj Kumar Sharma Ashok Veeraraghavan Department of Electrical and Computer Engineering Rice UniversityHoustonTXUSA Applied Physics Program Rice UniversityHoustonTXUSA

Wavefront sensing is the simultaneous measurement of the amplitude and phase of an incoming optical *** wavefront sensors such as Shack-Hartmann wavefront sensor(SHWFS)suffer from a fundamental tradeoff between spatial resolution and phase estimation and consequently can only achieve a resolution of a few thousand *** break this tradeoff,we present a novel computational-imaging-based technique,namely,the Wavefront Imaging Sensor with High resolution(WISH).We replace the microlens array in SHWFS with a spatial light modulator(SLM)and use a computational phase-retrieval algorithm to recover the incident *** wavefront sensor can measure highly varying optical fields at more than 10-megapixel resolution with the fine phase *** the best of our knowledge,this resolution is an order of magnitude higher than the current noninterferometric wavefront *** demonstrate the capability of WISH,we present three applications,which cover a wide range of spatial ***,we produce the diffraction-limited reconstruction for long-distance imaging by combining WISH with a large-aperture,low-quality Fresnel ***,we show the recovery of high-resolution images of objects that are obscured by ***,we show that WISH can be used as a microscope without an objective *** study suggests that the designing principle of WISH,which combines optical modulators and computational algorithms to sense high-resolution optical fields,enables improved capabilities in many existing applications while revealing entirely new,hitherto unexplored application areas.

关键词： estimation. field. resolution

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