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arXiv 2023年

作者： Fullerton, John McCray, Arthur R.C. Petford-Long, Amanda K. Phatak, Charudatta Materials Science Division Argonne National Laboratory LemontIL United States Applied Physics Program Northwestern University EvanstonIL United States Department of Materials Science and Engineering Northwestern University EvanstonIL United States

Comprehending the interaction between geometry and magnetism in three-dimensional (3D) nanostructures is of importance to understand the fundamental physics of domain wall (DW) formation and pinning. Here, we use focused electron beam-induced deposition to fabricate magnetic nanohelices with increasing helical curvature with height. Using electron tomography and Lorentz transmission electron microscopy, we reconstruct the 3D structure and magnetization of the nanohelices. The surface curvature, helical curvature and torsion of the nanohelices are then quantified from the tomographic reconstructions. Furthermore, by using the experimental 3D reconstructions as inputs for micromagnetic simulations we can reveal the influence of surface and helical curvature on the magnetic reversal mechanism. Hence, we can directly correlate the magnetic behavior of a 3D nanohelix to its experimental structure. These results demonstrate how control of geometry in nanohelices can be utilized in the stabilization of DWs and control of the response of the nanostructure to applied magnetic fields. Copyright © 2023, The Authors. All rights reserved.

关键词： Magnetization reversal

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Electronic-photonic quantum systems on-chip

Electronic-photonic quantum systems on-chip

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Quantum 2.0, QUANTUM 2022

作者： Wang, Imbert Ramesh, Anirudh Kramnik, Danielius Fargas Cabanillas, Josep M. Stojanović, Vladimir Kumar, Prem Popović, Miloš A. Department of Electrical and Computer Engineering Photonics Center Boston University BostonMA02215 United States Graduate Program in Applied Physics Northwestern University EvanstonIL60208 United States Department of Electrical Engineering and Computer Science UC Berkeley BerkeleyCA94720 United States Center for Photonic Communication and Computing Dept. of Electrical and Computer Eng. Northwestern University EvanstonIL60208 United States

We present progress towards realizing electronic-photonic quantum systems on-chip;particularly, entangled photon-pair sources, placing them in the context of previous work, and outlining our vision for mass-producible... 详细信息

ISBN: (纸本)9781957171111

关键词： Quantum entanglement

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Study of Novel Photodetectors and Electronics to Enhance Coincidence Time Resolution of BGO-based PET Detectors

Study of Novel Photodetectors and Electronics to Enhance Coi...

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： Andrea Gonzalez-Montoro Shirin Pourashraf Joshua W Cates Craig S Levin Department of Radiology Stanford University Stanford CA USA Applied Nuclear Physics Program Lawrence Berkeley National Laboratory Berkeley CA USA Departments of Radiology Molecular Imaging Program Bioengineering Physics and Electrical Engineering Stanford University CA USA

Developing high sensitivity multiparametric medical imaging tools constitutes one of the main research topics in radionuclide *** time-of-flight positron emission tomography (TOF-PET) scanners have shown potential in this context. One of the most attractive solutions that have been proposed to improve the coincidence time resolution (CTR) of TOF-PET scanners includes exploiting the small population of promptly emitted light photons (i.e., Cherenkov photons). Bismuth germanate (BGO) is a legacy detection material for PET which exhibits a moderate Cherenkov yield. which new advancements in ultra-violet (UV) light sensitive photosensor technologies and associated detection techniques can exploit for fast timing. It has been demonstrated that exploiting the BGO–Cherenkov component may simultaneously facilitate high 511 keV photon detection sensitivity with excellent CTR, thus enabling high sensitivity, low cost TOF-PET systems. Accessing the timing information from these Cherenkov photons requires enhanced photodetector technology combined with low noise and fast readout electronics, as well as specific data post-processing *** this summary, we report the CTR evaluation of different length BGO crystals coupled to UV enhanced SiPMs and custom designed electronics. Average CTR values of 156 ± 6, 188 ± 5, 228 ± 8 and 297 ± 8 ps CTR FWHM have been achieved for 3 × 3 × 3, × 5, × 10, and × 15 mm 3 BGO crystal with chemically processed surface finishes.

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Hyperuniformity of maximally random jammed packings of hyperspheres across spatial dimensions

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Physical Review E 2023年第6期108卷 064602-064602页

作者： Charles Emmett Maher Yang Jiao Salvatore Torquato Department of Chemistry Princeton University Princeton New Jersey 08544 USA Materials Science and Engineering Arizona State University Tempe Arizona 85287 USA Department of Physics Arizona State University Tempe Arizona 85287 USA Department of Physics Princeton University Princeton New Jersey 08544 USA Princeton Materials Institute Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA

The maximally random jammed (MRJ) state is the most random (i.e., disordered) configuration of strictly jammed (mechanically rigid) nonoverlapping objects. MRJ packings are hyperuniform, meaning their long-wavelength density fluctuations are anomalously suppressed compared to typical disordered systems, i.e., their structure factors S(k) tend to zero as the wave number |k| tends to zero. Here we show that generating high-quality strictly jammed states for Euclidean space dimensions d=3,4, and 5 is of paramount importance in ensuring hyperuniformity and extracting precise values of the hyperuniformity exponent α>0 for MRJ states, defined by the power-law behavior of S(k)∼|k|α in the limit |k|→0. Moreover, we show that for fixed d it is more difficult to ensure jamming as the particle number N increases, which results in packings that are nonhyperuniform. Free-volume theory arguments suggest that the ideal MRJ state does not contain rattlers, which act as defects in numerically generated packings. As d increases, we find that the fraction of rattlers decreases substantially. Our analysis of the largest truly jammed packings suggests that the ideal MRJ packings for all dimensions d≥3 are hyperuniform with α=d−2, implying the packings become more hyperuniform as d increases. The differences in α between MRJ packings and the recently proposed Manna-class random close packed (RCP) states, which were reported to have α=0.25 in d=3 and be nonhyperuniform (α=0) for d=4 and d=5, demonstrate the vivid distinctions between the large-scale structure of RCP and MRJ states in these dimensions. Our paper clarifies the importance of the link between true jamming and hyperuniformity and motivates the development of an algorithm to produce rattler-free three-dimensional MRJ packings.

关键词： Granular solids

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Novel synthesis of nickel-based bimetallic compounds using ammonium tetrafluoroborate and ammonium bifluoride as structure directing agents for energy storage application

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Journal of Energy Storage 2024年 75卷

作者： Kuo, Tsung-Rong Yu, You Zher Lee, Pin-Yan Wu, Chung-Hsien Chen, Hung-Ming Husain, Sadang Kongvarhodom, Chutima Ho, Kuo-Chuan Lin, Lu-Yin International PhD Program in Biomedical Engineering College of Biomedical Engineering Taipei Medical University Taipei11031 Taiwan Graduate Institute of Nanomedicine and Medical Engineering College of Biomedical Engineering Taipei Medical University Taipei11031 Taiwan Department of Chemical Engineering and Biotechnology National Taipei University of Technology Taipei Taiwan Department of Chemical Engineering National Taiwan University Taipei Taiwan Gingen Technology Co. LTD. Rm. 7 10F. No.189 Sec. 2 Keelung Rd. Xinyi Dist. Taipei11054 Taiwan Department of Physics Faculty of Mathematics and Natural Science Lambung Mangkurat University Banjarmasin70124 Indonesia Department of Chemical Engineering King Mongkut's University of Technology Thonburi 126 Pracha-u-thit Toong-kru Bangkok10140 Thailand

Nickel-based compounds are widely applied as the active material for energy storage devices, owing to high theoretical capacity and easy-fabricated process. Bimetallic compounds having multiple redox states can provide abundant redox reactions for charge storage. Structure directing agent (SDA) can promote the preferable growth of active materials and to enhance energy storage abilities. In this work, NH4BF4 and NH4HF2 are firstly used as SDA to synthesize nickel-based compounds along with 2-methylmidozole in the one-step solution process for energy storage applications. The bimetallic compounds are synthesized by incorporating Al, Mn, Co, Cu and Zn salts in the precursor solution including the Ni salt. The system with Al, Cu or Zn possesses single metal compound and barely nickel compound. Mn and Co-incorporated systems present clear bimetallic components with nickel hydroxide. The highest specific capacitance (CF) of 1336.3 F/g (297.0 mAh/g) are achieved at 20 mV/s for the NiCo-based electrode, owing to the bimetallic feature and favorable two-dimensional sheet-like structures. An energy storage device is assembled using the NiCo-based compound and reduced graphene oxide electrodes. The maximum energy density of 10.5 Wh/kg at 0.3 kW/kg, and the CF retention of 78.5% and Coulombic efficiency of 85.2% are achieved after 10,000 times charge/discharge cycles. © 2023 Elsevier Ltd

关键词： Energy storage

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Back action in quantum electro-optic sampling of electromagnetic vacuum fluctuations

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Physical Review Research 2023年第1期5卷 013151-013151页

作者： T. L. M. Guedes I. Vakulchyk D. V. Seletskiy A. Leitenstorfer A. S. Moskalenko Guido Burkard Department of Physics and Center for Applied Photonics University of Konstanz D-78457 Konstanz Germany Center for Theoretical Physics of Complex Systems Institute for Basic Science (IBS) Daejeon 34126 Republic of Korea Basic Science Program Korea University of Science and Technology (UST) Daejeon Korea 34113 Republic of Korea Department of Engineering Physics Polytechnique Montréal Montréal QC Canada H3T 1J4 Department of Physics KAIST Daejeon 34141 Republic of Korea

The influence of measurement back action on electro-optic sampling of electromagnetic quantum fluctuations is investigated. Based on a cascaded treatment of the nonlinear interaction between a near-infrared coherent probe and the mid-infrared vacuum, we account for the generated electric-field contributions that lead to detectable back action. Specifically, we theoretically address two realistic setups, exploiting one or two probe beams for the nonlinear interaction with the quantum vacuum, respectively. The setup parameters at which back action starts to considerably contaminate the measured noise profiles are determined. We find that back action starts to detrimentally affect the signal once the fluctuations due to the coupling to the mid-infrared vacuum become comparable to the base shot noise. Due to the vacuum fluctuations entering at the beam splitter, the shot noise of two incoming probe pulses in different channels is uncorrelated. Therefore, even when the base shot noise dominates the output of the experiment, it does not contribute to the correlation signal itself. However, we find that further contributions due to nonlinear shot-noise enhancement are still present. Ultimately, a regime in which electro-optic sampling of quantum fields can be considered as effectively back-action free is found.

关键词： Nonlinear optical susceptibility Optical coherence Optical tests of quantum theory Quantum field theory (low energy) Quantum fluctuations & noise Quantum information processing Quantum measurements Quantum states of light Ultrafast optics

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Memorial Viewpoint for Watt W. Webb: An Experimentalist's Experimentalist

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JOURNAL OF PHYSICAL CHEMISTRY B 2021年第11期125卷 2793-2795页

作者： Zipfel, Warren Xu, Chris Elson, Elliot Maiti, Sudipta Meinig School of Biomedical Engineering Cornell University Ithaca New York 14853 United States School of Applied and Engineering Physics Cornell University Ithaca New York 14853 United States Department of Biochemistry and Molecular Biophysics Washington University in St. Louis St. Louis Missouri 63110 United States Department of Chemical Sciences Tata Institute of Fundamental Research Mumbai 400005 India *

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Effect of Pd functionalization on optical and hydrogen sensing properties of ZnO: Eu films

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Optik 2025年 325卷

作者： Nagpal, Rajat Lupan, Cristian Buzdugan, Artur Ghenea, Vladislav Lupan, Oleg Center for Nanotechnology and Nanosensors Department of Microelectronics and Biomedical Engineering Faculty CIM Technical University of Moldova 168 Stefan cel Mare str. Chisinau MD-2004 Moldova Institute for Materials Science Chair for Functional Nanomaterials Faculty of Engineering Kaiserstraße 2 KielD-24143 Germany Institute of Applied Physics Moldova State University 60 str. Alexei Mateevici Chisinau MD-2009 Moldova

ZnO: Eu films have been functionalized with Pd nanoparticles of sizes (5–15 nm) synthesized by a chemical solution approach. Morphological and optical characterizations were carried out using SEM and transmission spectroscopy. The effects of Pd functionalization on the ZnO: Eu columnar microstructures have been investigated by analysing the photo response, photoresponsivity, external quantum efficiency (EQE), detectivity, and carrier dynamics rate. The Pd functionalized ZnO: Eu films (Pd40/ZnO: Eu) show a higher photo response (∼33), about three times higher compared to bare ZnO: Eu films (∼12.4) at 100 ℃. This can be explained by photocarrier transfer from the ZnO conduction band to the Fermi level of PdO and electron trapping on the sensing surface due to oxygen adsorption. A remarkable EQE and detectivity were found for both sample sets, Pd40/ZnO: Eu (∼930 %, ∼2˟1013 Jones) and ZnO: Eu (∼2030 %, ∼1.71˟1013 Jones). High UV–visible rejection ratio (R280 nm/R443 nm) of ∼82 is found, indicating good spectral selectivity. The effect of irradiance on photoresponsivity and recovery time has also been investigated and shows that increasing irradiance leads to an increase in electron-hole pair generation at a faster rate, contributing to higher photoresponsivity and faster recovery. Pd-functionalization results in higher gas sensing response of ∼15 and improved selectivity to 100 ppm hydrogen at lower operating temperatures for Pd40/ZnO: Eu films. The proposed columnar microstructures may enable advanced photodetector applications at relatively low bias voltage (∼50 mV). In this work, the importance towards Pd functionalization for H2 gas sensing and UV detection is presented. © 2025 The Authors

关键词： Photodetectors

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In-situ growth of novel iron oxide/iron organic framework composites as efficient electroactive materials of battery supercapacitor hybrids

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Journal of Energy Storage 2024年 97卷

作者： Kuo, Tsung-Rong Saukani, Muhammad Kuo, Tsung-Rong Kubendhiran, Subbiramaniyan Wang, Yu-Min Tai, Po-Chun Wu, Chang-Feng Lin, Lu-Yin Kongvarhodom, Chutima Kongvarhodom, Chutima Husain, Sadang Yougbaré, Sibidou Chen, Hung-Ming International PhD Program in Biomedical Engineering College of Biomedical Engineering Taipei Medical University Taipei11031 Taiwan Graduate Institute of Nanomedicine and Medical Engineering College of Biomedical Engineering Taipei Medical University Taipei11031 Taiwan Department of Chemical Engineering and Biotechnology National Taipei University of Technology Taipei Taiwan Department of Chemical Engineering King Mongkut's University of Technology Thonburi 126 Pracha-u-thit Toong-kru Bangkok10140 Thailand Department of Chemical Engineering University of New Brunswick FrederictonNBE3B5A3 Canada Department of Physics Faculty of Mathematics and Natural Science Lambung Mangkurat University Banjarmasin70124 Indonesia /Nanoro 03 B.P 7192 Ouagadougou03 Burkina Faso Gingen technology Co. LTD. Rm. 7 10F. No.189 Sec. 2 Keelung Rd. Xinyi Dist. Taipei11054 Taiwan

Iron oxide (Fe2O3) with a high theoretical capacitance, wide potential ranges and easy availability has attracted much attentions as the electrode material of battery supercapacitor hybrids (BSH). Metal–organic framework (MOF) is one of the promising potential energy storage materials due to its large surface area and controllable pore structures. In this work, novel iron oxide/iron organic framework composites (Fe2O3/FeMOF) are in-situ grown on the Ni foam as efficient energy storage electrodes of BSH. By tuning the solvothermal durations, the morphology changes from random sizes of sheets, regular grown vertical sheets, to flower-like structures. The d-spacing also increases for the Fe2O3/FeMOF synthesized using longer solvothermal durations. The optimal Fe2O3/FeMOF electrode synthesized using 9 h shows a high areal capacitance of 10.97 F/cm2 along with an areal capacity of 5.49 F/cm2 at the current density of 35 mA/cm2, owing to the most regular growth of sheets, the large d-spacing, and the smallest charge-transfer resistances. A BSH composed of the Fe2O3/FeMOF positive electrode and a graphene negative electrode shows a maximum energy density of 0.76 mWh/cm2 at 22.5 mW/cm2. The excellent long-term cycling stability with the capacitance retention of 85% and Coulombic efficiency of 98% are also achieved after 10,000 charge/discharge cycles. © 2024 Elsevier Ltd

关键词： Supercapacitor

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Optical coherence tomography angiography reveals retinal microvascular changes in patients with multiple sclerosis without optic neuritis

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ACTA OPHTHALMOLOGICA 2022年第Sup275期100卷

作者： Popa-Cherecheanu, Alina Bostan, Mihai Chua, Jacqueline Sim, Yin Ci Tan, Bingyao Bujor, Inna Garhofer, Gerhard Schmetterer, Leopold Ophthalmology Carol Davila University of Medicine and Pharmacy Ophthalmology Emergency University Hospital Singapore Eye Research Institute Singapore National Eye Centre Singapore Ophthalmology and Visual Sciences Academic Clinical Program Duke-NUS Medical School National University of Singapore SERI-NTU Advanced Ocular Engineering (STANCE) Singapore School of Chemical and Biological Engineering Nanyang Technological University Singapore Department of Clinical Pharmacology Medical University Vienna Center for Medical Physics and Biomedical Engineering Medical University Vienna Institute of Molecular and Clinical Ophthalmology Basel Switzerland

Purpose: Retinal imaging has attracted much interest as a non‐invasive low‐budget biomarker for neurological diseases such as multiple sclerosis (MS). Optical coherence tomography angiography (OCTA) is a functional extension of OCT and allows for the non‐invasive visualization of the retinal and choroidal microvasculature. We investigated retinal microvasculature changes in patients with relapsing–remitting MS (RRMS) without history of optic neuritis (ON) and compared them to a healthy control ***: The study was performed in a prospective, case–control design, including 58 participants (n = 100 eyes) with RRMS without ON and 78 age‐ and sex‐matched control participants (n = 136 eyes). OCTA images of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and choriocapillaris (CC) were obtained using a commercial OCTA system (Zeiss Cirrus HD‐5000 Spectral‐Domain OCT with AngioPlex OCTA, Carl Zeiss Meditec, Dublin, CA). Perfusion density (PD) and foveal avascular zone (FAZ) features (area and circularity) in both the SCP and DCP, as well as flow deficit in the CC were used as outcome ***: MS patients showed significantly increased PD in SCP (p = 0.003) and decreased PD in DCP (p < 0.001) as compared to controls when data were corrected for confounders. A significant difference was also noted when large vessels (LV) in the SCP were removed from the PD calculation (p = 0.004). Deep FAZ was significantly larger (p = 0.005) and less circular (p < 0.001) in the eyes of MS patients compared to healthy controls. Neither LV, PD or FAZ features in the SCP, nor flow deficits in the CC showed any statistically significant differences between the MS patients and the controls (p > 0.186).Conclusions: Our study shows that MS patients have microvascular changes in the macular parafoveal retina even without ON. They show increased PD in SCP and decreased PD in DCP. To which degree retinal biomarkers

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