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Postmortem ^(7)Li NMR analysis for assessing the reversibility of lithium metal electrodes in lithium metal batteries

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Journal of Energy Chemistry 2024年第7期94卷 430-440页

作者： Jaewon Baek Sunha kim hee-tak kim Oc hee han Department of Chemical&Biomolecular Engineering KAISTDaejeon 34141Republic of Korea Metropolitan Seoul Center Korea Basic Science InstituteSeoul 03759Republic of Korea Graduate School of Analytical Science&Technology Chungnam National UniversityDaejeon 34134Republic of Korea

Despite the proficiency of lithium(Li)-7 NMR spectroscopy in delineating the physical and chemical states of Li metal electrodes,challenges in specimen preparation and interpretation impede its *** this study,we conducted a comprehensive postmortem analysis utilizing ^(7)Li NMR,employing a stan-dard magic angle spinning probe to examine protective-layer coated Li metal electrodes and LiAg alloy electrodes against bare Li metal electrodes within Li metal batteries(LMBs).Our investigation explores the effects of sample burrs,alignment with the magnetic field,the existence of liquid electrolytes,and precycling on the ^(7)Li NMR *** contrasting NMR spectra before and after cycling,we identi-fied alterations in Li^(0) and Li^(+) signals attributable to the degradation of the Li metal *** NMR analyses decisively demonstrate the efficacy of the protective layer in mitigating dendrite and solid elec-trolyte interphase ***,we noted that Li*ions near the Li metal surface exhibit magnetic susceptibility anisotropy,revealing a novel approach to studying diamagnetic species on Li metal elec-trodes in *** study provides valuable insights and practical guidelines for characterizing distinct lithium states within LMBs.

关键词： NMR spectroscopy Lithium-7 Lithium metal battery Electrolyte Electrode-protective layer Solid electrolyte interface Magnetic susceptibility anisotropy Lithium-metal NMR signal Diamagnetic^(7)Li NMR signal

Anticipating the lifespan: Predicting the durability of an anode-supported solid oxide fuel cell short stack over 50,000 h

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Progress in Natural Science:Materials International 2024年第3期34卷 606-613页

作者： Muhammad Zubair Khan Amjad hussain Seung-Bok Lee tak-hyoung Lim Rak-hyun Song Department of Materials Science & Engineering Pak-Austria Fachhochschule: Institute of Applied Sciences and Technology hydrogen Energy Research Division Korea Institute of Energy Research Department of Advanced Energy and System Engineering Korea University of Science and Technology (UST)

In the present study, the operational lifetime of a solid oxide fuel(SOFC) short stack is predicted by investigating the performance degradation of both the short stack and its cells throughout 1000 h at 800°C. The short stack and integral cell voltages are continuously measured during the long-term test, with electrochemical impedance spectroscopy(EIS) conducted every 200 h. The short stack voltage decreased rapidly for the initial 200–300 h and afterwards, it decreased at a slow rate due to the increase in the Ohmic and polarization resistances in the same manner. Scanning electron microscopy results show that there is no delamination or cracking among constituent layers of the short-stack cells. The single degradation effects of the Ni coarsening in the anode, cation migration and surface segregation in cathode and oxide scale growth in metallic interconnect mesh are successfully integrated into a comprehensive lifetime prediction model. The experimentally measured voltage degradation data of the short stack fits well with the developed mathematical model and allows the successful prediction of the lifetime up to 50,000 h.

关键词： Degradation Impedance Lifetime SOFC Stack

Superplasticity of fine-grained Mg-10Li alloy prepared by severe plastic deformation and understanding its deformation mechanisms

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Journal of Magnesium and Alloys 2024年第1期12卷 316-331页

作者： h.T.Jeong S.W.Lee W.J.kim Department of Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul 121-791Republic of Korea

The superplastic behavior and associated deformation mechanisms of a fine-grained Mg-10.1 Li-0.8Al-0.6Zn alloy(LAZ1011)with a grain size of 3.2μm,primarily composed of the BCCβphase and a small amount of the hCPαphase,were examined in a temperature range of 473 K to 623 *** microstructural refinement of this alloy was achieved by employing high-ratio differential speed *** best superplasticity was achieved at 523 K and at strain rates of 10^(-4)-5×10^(-4)s^(-1),where tensile elongations of 550±600%were *** the heating and holding stage of the tensile samples prior to tensile loading,a significant increase in grain size was observed at temperatures above 573 ***,it was important to consider this effect when analyzing and understanding the superplastic deformation behavior and *** the investigated strain rate range,the superplastic flow at low strain rates was governed by lattice diffusion-controlled grain boundary sliding,while at high strain rates,lattice diffusion-controlled dislocation climb creep was the rate-controlling deformation *** was concluded that solute drag creep is unlikely to *** the late stages of deformation at 523 K,it was observed that grain boundary sliding led to the agglomeration of theαphase,resulting in significant strain *** mechanism maps were constructed forβ-Mg-Li alloys in the form of 2D and 3D formats as a function of strain rate,stress,temperature,and grain size,using the constitutive equations for various deformation mechanisms derived based on the data of the current tests.

关键词： Magnesium-lithium alloy Superplasticity Severe plastic deformation Grain size Grain growth

Boosted Lithium-Ion Transport Kinetics in n-Type Siloxene Anodes Enabled by Selective Nucleophilic Substitution of Phosphorus

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Nano-Micro Letters 2024年第10期16卷 618-637页

作者： Se In kim Woong-Ju kim Jin Gu Kang Dong-Wan kim School of Civil Environmental and Architectural EngineeringKorea University02841 SeoulSouth Korea Nanophotonics Research Center Korea Institute of Science and Technology02792 SeoulSouth Korea

Doped two-dimensional(2D)materials hold significant promise for advancing many technologies,such as microelectronics,optoelectronics,and energy ***,n-type 2D oxidized Si nanosheets,namely n-type siloxene(n-SX),are employed as Li-ion battery *** thermal evaporation of sodium hypophosphite at 275℃,P atoms are effectively incorporated into siloxene(SX)without compromising its 2D layered morphology and unique Kautsky-type crystal ***,selective nucleophilic substitution occurs,with only Si atoms being replaced by P atoms in the O_(3)≡Si-h *** resulting n-SX possesses two delocalized electrons arising from the presence of two electron donor types:(i)P atoms residing in Si sites and(ii)h *** doping concentrations are varied by controlling the amount of precursors or their mean free *** at 2000 mA g^(-1),the n-SX electrode with the optimized doping concentration(6.7×10^(19) atoms cm^(-3))delivers a capacity of 594 mAh g^(-1) with a 73%capacity retention after 500 *** improvements originate from the enhanced kinetics of charge transport processes,including electronic conduction,charge transfer,and solid-state *** approach proposed herein offers an unprecedented route for engineering SX anodes to boost Li-ion storage.

关键词： Li-ion battery Two-dimensional N-type siloxene Doping mechanism Kinetics

Three cases of uncommon medication-associated osteonecrosis of temporal bone

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世界耳鼻咽喉头颈外科杂志英文版 2024年第3期10卷 237-240页

作者： VanDolah hunter Crossley Jason R. Jeffrey kim h. Georgetown University School of Medicine Washington DC USA Department of Otolaryngology–head and Neck Surgery MedStar Georgetown University Hospital Washington DC USA

Introduction: Medication-related osteonecrosis of the temporal bone is rare and has been reported to be associated with the use of anti-resorptive and biologic agents. here, we present the first case of tyrosine-kinase inhibitor-related external auditory canal (EAC) osteonecrosis as well as two cases related to anti-resorptive ***: A retrospective case ***: Case one: an 84-year-old female presented with chronic otitis externa and osteonecrosis of EACs bilaterally. She had a history of osteoporosis treated with denosumab and risedronic acid. She successfully underwent left EAC reconstruction using an inferiorly-based pedicle periosteal flap while the right ear canal was managed conservatively. Case two: a 69-year-old male presented with osteonecrosis of the right EAC. he had a history of osteoporosis treated with alendronic acid and zoledronic acid. his osteonecrosis is conservatively managed with local debridement and antibiotic application. Case three: a 60-year-old male presented with osteonecrosis of the right inferior EAC. he had a history of chronic myelogenous leukemia treated with a tyrosine-kinase inhibitor, imatinib. After failing conservative therapy, he underwent right ear canal reconstruction using a periosteal vascular pedicle flap without complication and experienced complete resolution to his ***: Anti-resorptive agents and/or tyrosine kinase inhibitors may lead to dysregulation of bone remodeling and result in rare cases of temporal bone osteonecrosis. When a local debridement and antibiotic therapy fail, definitive surgical excision of necrotic bone with subsequent reconstruction of the EAC may offer patients a possible resolution in symptoms.

关键词： bisphosphonates denosumab external auditory canal imatinib medication-related osteonecrosis osteonecrosis temporal bone tyrosine-kinase Inhibitors

Measuring nanoscale friction at graphene step edges

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Friction 2020年第4期8卷 802-811页

作者： Zhe ChEN Seong h.kim Department of Chemical Engineering and Materials Research Institute Pennsylvania State UniversityUniversity ParkPA 16802USA

Although graphene is well known for super-lubricity on its basal plane, friction at its step edge is not well understood and contradictory friction behaviors have been reported. In this study, friction of mono-layer thick graphene step edges was studied using atomic force microscopy (AFM) with a Si tip in dry nitrogen atmosphere. It is found that, when the tip slides over a'buried' graphene step edge, there is a resistive force during the step-up motion and an assistive force during the step-down motion due to the topographic height change. The magnitude of these two forces is small and the same in both step-up and step-down motions. As for the'exposed' graphene step edge, friction increases in magnitude and exhibits more complicated behaviors. During the step-down motion of the tip over the exposed step edge, both resistive and assistive components can be detected in the lateral force signal of AFM if the scan resolution is sufficiently high. The resistive component is attributed to chemical interactions between the functional groups at the tip and step-edge surfaces, and the assistive component is due to the topographic effect, same as the case of buried step edge. If a blunt tip is used, the distinct effects of these two components become more prominent. In the step-up scan direction, the blunt tip appears to have two separate topographic effects–elastic deformation of the contact region at the bottom of the tip due to the substrate height change at the step edge and tilting of the tip while the vertical position of the cantilever (the end of the tip) ascends from the lower terrace to the upper terrace. The high-resolution measurement of friction behaviors at graphene step edges will further enrich understanding of interfacial friction behaviors on graphene-covered surfaces.

关键词： friction graphene step edge atomic force microscopy tip bluntness

Complex regulatory effects of gut microbial short-chain fatty acids on immune tolerance and autoimmunity

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Cellular & Molecular Immunology 2023年第4期20卷 341-350页

作者： Chang h.kim Department of Pathology University of Michigan School of MedicineAnn ArborMI48109USA Mary h.Weiser Food Allergy Center Center for Gastrointestinal Researchand Rogel Center for Can

Immune tolerance deletes or suppresses autoreactive lymphocytes and is established at multiple levels during the development,activation and effector phases of T and B *** mechanisms are cell-intrinsically programmed and critical in preventing autoimmune *** have witnessed the existence of another type of immune tolerance mechanism that is shaped by lifestyle choices,such as diet,microbiome and microbial ***-chain fatty acids(SCFAs)are the most abundant microbial metabolites in the colonic lumen and are mainly produced by the microbial fermentation of prebiotics,such as dietary *** review focuses on the preventive and immunomodulatory effects of SCFAs on *** tissue-and disease-specific effects of dietary fiber,SCFAs and SCFA-producing microbes on major types of autoimmune diseases,including type I diabetes,multiple sclerosis,rheumatoid arthritis and lupus,are ***,their key regulatory mechanisms for lymphocyte development,tissue barrier function,host metabolism,immunity,autoantibody production,and inflammatory effector and regulatory lymphocytes are *** shared and differential effects of SCFAs on different types and stages of autoimmune diseases are discussed.

关键词： Short-chain fatty acids Immune tolerance Diabetes mellitus Rheumatoid arthritis Lupus Multiple sclerosis

Control of lymphocyte functions by gut microbiota-derived short-chain fatty acids

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Cellular & Molecular Immunology 2021年第5期18卷 1161-1171页

作者： Chang h.kim Department of Pathology and Mary h.Weiser Food Allergy Center University of Michigan School of MedicineAnn ArborMIUSA

A mounting body of evidence indicates that dietary fiber(DF)metabolites produced by commensal bacteria play essential roles in balancing the immune ***,considered nonessential nutrients in the past,is now considered to be necessary to maintain adequate levels of immunity and suppress inflammatory and allergic ***-chain fatty acids(SCFAs),such as acetate,propionate,and butyrate,are the major DF metabolites and mostly produced by specialized commensal bacteria that are capable of breaking down DF into simpler saccharides and further metabolizing the saccharides into *** act on many cell types to regulate a number of important biological processes,including host metabolism,intestinal functions,and immunity *** review specifically highlights the regulatory functions of DF and SCFAs in the immune system with a focus on major innate and adaptive *** information regarding how SCFAs regulate innate lymphoid cells,T helper cells,cytotoxic T cells,and B cells and how these functions impact immunity,inflammation,and allergic responses are discussed.

关键词： Microbiota Dietary fiber Short-chain fatty acids Innate lymphoid cells B cells Th1 Th17 Tregs CD8 Microbial metabolites

Soleus arthrogenic muscle inhibition following acute lateral ankle sprain correlates with symptoms and ankle disability but not with postural control

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Journal of Sport and health Science 2024年第4期13卷 559-568,F0003页

作者： Kyung-Min kim Joo-Sung kim Alan R.Needle Department of Sport Science Sungkyunkwan UniversitySuwon-si 16419Republic of Korea Department of health and human Performance Texas State UniversitySan MarcosTX 78666USA Department of Public health&Exercise Science Appalachian State UniversityBooneNC 28608USA Department of Rehabilitation Science Appalachian State UniversityBooneNC 28608USA

Background:Acute lateral ankle sprains(ALAS)are associated with long-term impairments and instability tied to altered neural *** muscle inhibition(AMI)has been observed in this population;however,relationships with injury-related impairments are unclear,potentially due to the resting,prone position in which AMI is typically *** AMI during bipedal stance may provide a better understanding of this ***:AMI was assessed in 38 young adults(19 ALAS within 72 h of injury:10 males,21.4±2.7 years;19 healthy controls:10 males,21.9±2.2 years;mean±SD)using the hoffmann reflex(h-reflex)during bipedal *** stimulation was administered to identify the _(max)imal h-reflex(h_(max))and _(max)imal motor response(M_(max))from the soleus,fibularis longus,and tibialis anterior *** primary outcome measure was the h_(max)/M_(max) *** outcomes included acute symptoms(pain and swelling),postural control during bipedal stance,and self-reported ***:No significant group-by-limb interactions were observed for any ***,a significant group main effect was observed in the soleus muscle(F(1,35)=6.82,p=0.013),indicating significantly lower h_(max)/M_(max) ratios following ALAS(0.38±0.20)compared to healthy controls(0.53±0.16).Furthermore,lower h_(max)/M_(max) ratios in the soleus significantly correlated with acute symptoms and self-reported function but not with postural ***:This study supports previous evidence of AMI in patients with ALAS,providing insight into neurophysiologic impacts of musculoskeletal *** results suggest that assessing AMI in a standing position following acute injury may provide valuable insight into how AMI develops and guide potential therapeutic options to curb and offset the formation of joint instability.

关键词： Acute injuries Balance hoffmann reflex Neural excitability Patient-reported outcomes