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Multifaceted progress in high-field superconducting magnet mechanics

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Acta Mechanica Sinica 2024年第4期40卷 1-3页

作者： Xingzhe Wang Seungyong hahn Key Laboratory of Mechanics on Western Disaster and Environment Ministry of EducationCollege of Civil Engineering and MechanicsLanzhou UniversityLanzhou 730000China Department of Electrical and Computer Engineering Seoul National UniversitySeoul 08826Republic of Korea

High-field superconducting magnets are poised to revolutionize technologies,including particle accelerators,magnetic resonance imaging(MRI)machines,and fusion *** stand at the frontier of superconductor ***_(3)Sn wires,which operate at cold temperatures,along with rare-earth barium copper oxide(REBCO)coated conductors that include rare earth elements like Y,Gd,and Dy,are gaining *** high electrical efficiency in strong magnetic fields makes them particularly attractive for such advanced applications.

关键词： Nb_(3)Sn field earth

Solvation Effects on the Dielectric Constant of 1 M LiPF6 in Ethylene Carbonate:Ethyl Methyl Carbonate 3:7

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Energy & Environmental Materials 2024年第1期7卷 253-256页

作者： Julian Self Nathan T.hahn Kristin A.Persson Department of Chemical Engineering Polytechnique MontrealMontrealQC H3T 1J4Canada Department of Materials Science and Engineering University of CaliforniaBerkeleyCA 94720USA Energy Technologies Area Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA Material Physical and Chemical Sciences CenterSandia National LaboratoriesAlbuquerqueNM 87185USA

We report the dielectric constant of 1 M LiPF_(6)in EC:EMC 3∶7 w/w(ethylene carbonate/ethyl methyl carbonate)in addition to neat EC:EMC 3∶7 w/*** three Debye relaxations,the static permittivity value,or dielectric constant,is extrapolated to 18.5,which is compared to 18.7 for the neat solvent *** EC solvent is found to strongly coordinate with the Li^(+)cations of the salt,which results in a loss of dielectric contribution to the ***,the small amplitude and large uncertainty in relaxation frequency for EMC cloud definitive identification of the Li^(+)solvation ***,the loss of the free EC permittivity contribution due to Li^(+)solvation is almost completely balanced by the positive contribution of the associated LiPF_(6)salt,demonstrating that a significant quantity of dipolar ion pairs exists in 1 M LiPF_(6)in EC:EMC 3∶7.

关键词： batteries dielectric relaxation spectroscopy electrolytes

Enhanced activity and durability of FeCoCrMoCBY nanoglass in acidic hydrogen evolution reaction

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Journal of Materials Science & Technology 2024年第3期170卷 212-220页

作者： Mengyang Yan Shuangqin Chen Shangshu Wu Xuechun Zhou Shu Fu Di Wang Christian Kübel Horst hahn Si Lan Tao Feng Herbert Gleiter Institute of Nanoscience School of Material Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China Institute of Nanotechnology Karlsruhe Institute of TechnologyKarlsruhe 76021Germany

In the present work,a multi-element nanoglass(m-NG)of FeCoCrMoCBY is obtained first time by the laser ablation combined with inert gas condensation(laser-IGC)*** with the conventional rapid-quenched metallic glass(MG)with identical composition,the Fe-based m-NG demonstrates a superior performance as a self-supported electrocatalyst for hydrogen evolution reaction(HER)in acidic *** enhanced HER activity of m-NG is proposed to be closely related to its high en-ergy states,which is originated from the unique inhomogeneous nanostructures with a high density of low-coordinated ***,the Fe-based m-NG exhibits an outstanding comprehensive catalytic performance even beyond the commercial Pt/C catalyst in long-term test due to its self-optimization *** work not only opens the way to the preparation of m-NGs by the novel laser-IGC technique,but also makes a great contribution to developing low-cost,high-efficient,and super-durable HER electrocat-alysts in acidic environment.

关键词： Nanoglass Inert gas condensations High energy states Hydrogen evolution reactions

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计算超导螺线管磁体中电磁应力的解析方法

Acta Mechanica Sinica 2024年第4期40卷 4-20页

作者： Jeonghwan Park Kibum Choi Yufan Yan Jaemin Kim Seungyong hahn Department of Electrical and Computer Engineering Seoul National UniversitySeoul08826Republic of Korea Applied Superconductivity Center and Electric Power Institute Seoul National UniversitySeoul08826Republic of Korea

在高场磁体中,压缩磁径向应力比拉伸应力更受青睐,原因是它能降低磁体绕组内的整体峰值磁应力.这对于无绝缘高温超导(NI HTS)磁体尤为重要,因为压缩径向应力能够产生良好的匝间接触,这对于无绝缘高温超导线圈中的电流共享以及随之而来... 详细信息

在高场磁体中,压缩磁径向应力比拉伸应力更受青睐,原因是它能降低磁体绕组内的整体峰值磁应力.这对于无绝缘高温超导(NI HTS)磁体尤为重要,因为压缩径向应力能够产生良好的匝间接触,这对于无绝缘高温超导线圈中的电流共享以及随之而来的自保护行为至关重要.根据关键磁体设计参数(如目标中心场、背景磁场、内外绕组直径和外部径向堆叠),我们给出了可以从解析上确定高场超导磁体具有压缩径向应力的电磁-力学条件.本文提出的方法可以识别干绕线圈中径向匝间接触行为的3种不同模式:(1)完全分离;(2)完全接触;以及(3)混合模式(即部分分离和接触).文章随后提出一种使用完全压缩径向应力电磁-力学条件来计算干绕线圈中应力分布的解析方法.并通过有限元分析示例验证了解析方法与数值方法的良好一致性.文章结果可以帮助磁体工程师在早期设计阶段更好地概览高场超导磁体的电磁-力学行为.

关键词：高温超导背景磁场径向应力力学条件拉伸应力匝间接触行为混合模式

Screening-current-induced magnetic fields and strains in a compact REBCO coil in self field and background field

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Superconductivity 2024年第1期9卷 35-49页

作者： Yufan Yan Donghui Jiang Peng Song Jeonghwan Park Seungyong hahn Yunfei Tan Timing Qu Department of Electrical and Computer Engineering Seoul National UniversitySeoul 08826Republic of Korea State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China High Magnetic Field Laboratory Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China Wuhan National High Magnetic Field Center Huazhong University of Science and TechnologyWuhan 430074China

REBa_(2)Cu_(3)O_(7−x)(REBCO)coated conductors,owing to its high tensile strength and current‐carrying ability in a background field,are widely regarded a promising candidate in high‐field *** the great potentials,recent studies have highlighted the challenges posed by screening currents,which are featured by a highly nonuniform current distribution in the superconducting *** this paper,we report a comprehensive study on the behaviors of screening currents in a compact REBCO coil,specifically the screeningcurrent‐induced magnetic fields and *** were carried out in the self‐generated magnetic field and a background field,*** the self‐field condition,the full hysteresis of the magnetic field was obtained by applying current sweeps with repeatedly reversed polarity,as the nominal center field reached 9.17 T with a maximum peak current of 350 *** a background field of 23.15 T,the insert coil generated a center field of 4.17 T with an applied current of 170 ***,a total center field of 32.58 T was achieved before *** the sequential model and the coupled model considering the perpendicular field modification due to conductor deformation are *** comparative study shows that,for this coil,the electromagnetic–mechanical coupling plays a trivial role in self‐field conditions up to 9 *** contrast,with a high axial field dominated by the background field,the coupling effect has a stronger influence on the predicted current and strain *** discussions regarding the role of background field on the strains in the insert suggest potential design strategies to maximize the total center field.

关键词： Electromagnetic-mechanical analysis High‐field insert coil REBCO coated conductor Screening‐current‐induced magnetic field Screening‐current‐induced stress

Prenatal and postnatal factors associated with sudden infant death syndrome:an umbrella review of meta-analyses

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World Journal of Pediatrics 2024年第5期20卷 451-460页

作者： Tae Hyeon Kim Hyeri Lee Selin Woo Hayeon Lee Jaeyu Park Guillaume Fond Laurent Boyer Jong Woo hahn Jiseung Kang Dong Keon Yon Department of Medicine Kyung Hee University College of MedicineSeoulSouth Korea Center for Digital Health Medical Science Research InstituteKyung Hee University College of MedicineSeoulSouth Korea Department of Regulatory Science Kyung Hee UniversitySeoulSouth Korea Department of Biomedical Engineering Kyung Hee UniversityYonginSouth Korea CEReSS-Health Service Research and Quality of Life Center Assistance Publique des Hôpitaux de MarseilleAix-Marseille UniversityMarseilleFrance Department of Pediatrics Seoul National University College of MedicineSeoulSouth Korea Department of Pediatrics Seoul National University Bundang HospitalSeongnamSouth Korea Department of Anesthesia Critical Care and Pain MedicineMassachusetts General Hospital14913th StreetRoom 4140CharlestownBostonMAUSA Division of Sleep Medicine Harvard Medical SchoolBostonMAUSA Department of Pediatrics Kyung Hee University Medical CenterKyung Hee University College of Medicine23 Kyungheedae-roDongdaemun-guSeoul02447South Korea Department of Precision Medicine Kyung Hee University College of MedicineSeoulSouth Korea

Background Comprehensive quantitative evidence on the risk and protective factors for sudden infant death syndrome(SIDS)effects is *** investigated the risk and protective factors related to *** We conducted an umbrella review of meta-analyses of observational and interventional studies assessing SIDS-related ***/MEDLINE,Embase,EBSCO,and Google Scholar were searched from inception until January 18,*** extraction,quality assessment,and certainty of evidence were assessed by using A Measurement Tool Assessment Systematic Reviews 2 following PRISMA *** to observational evidence,credibility was graded and classified by class and quality of evidence(CE;convincing,highly suggestive,suggestive,weak,or not significant).Our study protocol was registered with PROSPERO(CRD42023458696).The risk and protective factors related to SIDS are presented as equivalent odds ratios(eORs).Results We identified eight original meta-analyses,including 152 original articles,covering 12 unique risk and protective factors for SIDS across 21 countries/regions and five *** risk factors,including prenatal drug exposure[eOR=7.84(95%CI=4.81–12.79),CE=highly suggestive],prenatal opioid exposure[9.55(95%CI=4.87–18.72),CE=suggestive],prenatal methadone exposure[9.52(95%CI=3.34–27.10),CE=weak],prenatal cocaine exposure[4.38(95%CI=1.95–9.86),CE=weak],prenatal maternal smoking[2.25(95%CI=1.95–2.60),CE=highly suggestive],postnatal maternal smoking[1.97(95%CI=1.75–2.22),CE=weak],bed sharing[2.89(95%CI=1.81–4.60),CE=weak],and infants found with heads covered by bedclothes after last sleep[11.01(95%CI=5.40–22.45),CE=suggestive],were *** the other hand,three protective factors,namely,breastfeeding[0.57(95%CI=0.39–0.83),CE=non-significant],supine sleeping position[0.48(95%CI=0.37–0.63),CE=suggestive],and pacifier use[0.44(95%CI=0.30–0.65),CE=weak],were also *** Based on the evidence,we propose several risk and protecti

关键词： Infant Protective factor Risk factor Sudden infant death syndrome Umbrella review

A multi-photon(7×7)-focus 3D laser printer based on a 3D-printed diffractive optical element and a 3D-printed multi-lens array

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Light(Advanced Manufacturing) 2024年第1期5卷 26-39页

作者： Pascal Kiefer Vincent hahn Sebastian Kalt Qing Sun Yolita M.Eggeler Martin Wegener DMM2O-Cluster of Excellence Karlsruhe Institute of Technology(KIT)and Heidelberg University76128 KarlsruheGermany Institute of Applied Physics(APH) Karlsruhe Institute of Technology(KIT)76128 KarlsruheGermany Institute of Nanotechnology(INT) Karlsruhe Institute of Technology(KIT)76128 KarlsruheGermany Laboratory for Electron Microscopy(LEM) Karlsruhe Institute of Technology(KIT)76128 KarlsruheGermany

One of the challenges in the field of multi-photon 3D laser printing lies in further increasing the print speed in terms of voxels/***,we present a setup based on a 7×7 focus array(rather than 3×3 in our previous work)and using a focus velocity of about 1 m/s(rather than 0.5 m/s in our previous work)at the diffraction limit(40×/NA1.4 microscope objective lens).Combined,this advance leads to a ten times increased print speed of about 108 voxels/*** demonstrate polymer printing of a chiral metamaterial containing more than 1.7×10^(12) voxels as well as millions of printed microparticles for potential pharmaceutical *** critical high-quality micro-optical components of the setup,namely a diffractive optical element generating the 7×7 beamlets and a 7×7 lens array,are manufactured by using a commercial two-photon grayscale 3D laser printer.

关键词： 3D laser printing Direct laser writing Multi-photon absorption Multi-focus optics Diffractive optical element Lens array

Neuralgic amyotrophy with hourglass-like constrictions:A case report

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World Journal of Clinical Cases 2024年第34期12卷 6728-6735页

作者： Mi-Hyeon Bang Ha-Lim Song Seok hahn Wanil Kim Hwan-Kwon Do Department of Physical Medicine and Rehabilitation Haeundae Paik HospitalInje University College of MedicineBusan 48108South Korea Department of Radiology Haeundae Paik HospitalInje University College of MedicineBusan 48108South Korea Division of Biochemistry Department of Convergence Medical ScienceInstitute of Medical ScienceGyeongsang National University College of MedicineJinju 52727South Korea Department of Physical Medicine and Rehabilitation Dongnam Institute of Radiological and Medical SciencesBusan 46033South Korea

BACKGROUND Neuralgic amyotrophy(NA)is a rare disease with sudden upper limb pain followed by affected muscle *** most commonly affected area in NA is the upper part of the brachial plexus,and the paraspinal muscles are rarely affected(1.5%),making these cases difficult to distinguish from cervical *** SUMMARY A 76-year-old male presented to the emergency department with left hip pain *** undergoing left femoral neck fracture surgery,he experienced sudden left shoulder pain for 10 days with subsequent left arm *** spine computed tomography revealed mild right asymmetric intervertebral disc bulging with a decreased C5-6disc *** weeks later,an electrodiagnostic study confirmed brachial plexopathy findings involving the cervical *** resonance neurography was performed for a differential *** enhancement was identified at the upper trunk of the brachial plexus,including the C5 nerve root.A suprascapular nerve hourglass-like focal constriction(HLFC)was also identified,confirming *** being diagnosed with NA,the patient received 15 mg prednisolone,twice daily,for 3 *** therapy was initiated,including left arm strengthening exercises and electrical stimulation *** shoulder muscle strength significantly improved one CONCLUSION NA's unique features like HLFC and paraspinal involvement are crucial for accurate diagnosis,avoiding confusion with cervical radiculopathy.

关键词： Neuralgic amyotrophy Cervical radiculopathy Hourglass-like focal constriction Paraspinal muscle Magnetic resonance neurography Case report

Insights into the radial water jet drilling technology-Application in a quarry

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第2期10卷 236-248页

作者： Thomas Reinsch Bob Paap Simon hahn volker Wittig Sidney van den Berg GFZ German Research Centre for Geosciences Telegrafenberg14473 PotsdamGermany TNO Sustainable Geo EnergyUtrechtThe Netherlands International Geothermal Centre-GZB Lennershofstr.14044801 BochumGermany Well Services Group Phileas Foggstraat 65NL-7825 AL EmmenThe Netherlands

In this context, we applied the radial water jet drilling(RJD) technology to drill five horizontal holes into a quarry wall of the Gildehaus quarry close to Bad Bntheim, Germany. For testing the state-of-the-art jetting technology, a jetting experiment was performed to investigate the influence of geological heterogeneity on the jetting performance and the hole geometry, the influence of nozzle geometry and jetting pressure on the rate of penetration, and the possibility of localising the jetting nozzle utilizing acoustic activity. It is observed that the jetted holes can intersect fractures under varying angles, and the jetted holes do not follow a straight path when jetting at ambient surface condition. Cuttings from the jetting process retrieved from the holes can be used to estimate the reservoir rock permeability. Within the quarry, we did not observe a change in the rate of penetration due to jetting pressure *** monitoring was partially successful in estimating the nozzle location. Although the experiments were performed at ambient surface conditions, the results can give recommendations for a downhole application in deep wells.

关键词： Acoustic monitoring Drilling performance Trajectory Permeability Rock properties Radial water jet drilling(RJD)