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Accelerated biodegradation of iron-based implants via tantalum-implanted surface nanostructures

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Bioactive Materials 2022年第3期7卷 239-250页

作者： Min-Kyu lee Hyun lee Cheonil Park In-gu Kang Jinyoung Kim Hyoun-Ee Kim Hyun-Do jung Tae-Sik Jang Department of Materials Science and Engineering Seoul National UniversitySeoul08826Republic of Korea Querrey Simpson Institute for Bioelectronics Northwestern UniversityEvanstonIL60208USA Department of Biomedical-Chemical Engineering Catholic University of KoreaBucheon14662Republic of Korea Department of Biotechnology The Catholic University of KoreaBucheon14662Republic of Korea Department of Materials Science and Engineering Chosun UniversityGwangju61452Republic of Korea

In recent years,pure iron(Fe)has attracted significant attention as a promising biodegradable orthopedic implant material due to its excellent mechanical and biological properties.However,in physiological conditions,Fe has an extremely slow degradation rate with localized and irregular degradation,which is problematic for practical applications.In this study,we developed a novel combination of a nanostructured surface topography and galvanic reaction to achieve uniform and accelerated degradation of an Fe implant.The target-ion induced plasma sputtering(TIPS)technique was applied on the Fe implant to introduce biologically compatible and electrochemically noble tantalum(Ta)onto its surface and develop surface nano-galvanic couples.Electrochemical tests revealed that the uniformly distributed nano-galvanic corrosion cells of the TIPS-treated sample(nano Ta-Fe)led to relatively uniform and accelerated surface degradation compared to that of bare Fe.Furthermore,the mechanical properties of nano Ta-Fe remained almost constant during a long-term in vitro immersion test(~40 weeks).Biocompatibility was also assessed on surfaces of bare Fe and nano Ta-Fe using in vitro osteoblast responses through direct and indirect contact assays and an in vivo rabbit femur medullary cavity implantation model.The results revealed that nano Ta-Fe not only enhanced cell adhesion and spreading on its surface,but also exhibited no signs of cellular or tissue toxicity.These results demonstrate the immense potential of Ta-implanted surface nanostructures as an effective solution for the practical application of Fe-based orthopedic implants,ensuring long-term biosafety and clinical efficacy.

关键词： Iron Tantalum Ion implantation Biodegradation Orthopedic implants

Fabrication of high-strength duplex nanoporous Cu by dealloying a dual-phase Mg-Cu precursor alloy

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Journal of Magnesium and Alloys 2020年第3期8卷 910-916页

作者： Si-Young lee Soo-Min Baek Eun-Ji Gwak Na-Ri Kang Ju-Young Kim Su-Hyeon Kim jung Gu Lee Sung Soo Park School of Materials Science and Engineering Ulsan National Institute of Science and TechnologyUlsan 44919Republic of Korea Korea Institute of Materials Science Changwon 51508Republic of Korea School of Materials Science and Engineering University of UlsanUlsan 44610Republic of Korea

Duplex nanoporous Cu was successfully fabricated by dealloying a dual-phase Mg-Cu precursor alloy consisting of intermetallic Mg2Cu and MgCu2.The duplex nanoporous Cu with embedded nanoporous struts exhibited highly enhanced strength compared to the typical monolithic nanoporous Cu under both compressive and flexural test conditions at room temperature;the duplex np-Cu sample exhibited a 12 times higher compressive strength and a 40 times greater flexural strength than the monolithic np-Cu sample.Factors responsible for the strength enhancement in the duplex nanoporous Cu are discussed.

关键词： Mg-Cu alloy Nanoporous Cu Dealloying Duplex structure Strength

High performance of TiO_(2)/Cu_(x)O photoelectrodes for regenerative solar energy storage in a vanadium photoelectrochemical cell

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Green Energy & Environment 2022年第4期7卷 704-711页

作者： Harin Yoo Doohwan lee jung Hyeun Kim Department of Chemical Engineering University of Seoul163 SiripdaeroDongdaemun-guSeoul02504South Korea

Photocatalysts for harvesting solar energy to either electricity or chemical fuels have attracted much attention recently, but they have big obstacles such as wide bandgaps and rapid charge recombinations to overcome for final applications. In this study, we investigates a useful method to utilize vanadium redox pairs, which are commonly applied for vanadium redox flow batteries, to diminish charge recombinations and thus to enhance photocurrent response in regenerative solar energy storage. The results reveal significant improvements in photocurrent density by forming cuprous and cupric oxides in TiO_(2)/Cu_(x)O electrodes under solar AM 1.5 illuminations using the vanadium photoelectrochemical storage cell at 0.025 mol L^(-1) of vanadium redox species in the acid electrolytes. In addition, the stabilized photocurrent density of the copper content optimized TiO_(2)/Cu_(x)O electrodes is almost tripled from the TiO_(2) only electrode because the charge recombinations can be mitigated with the content optimized TiO_(2)/Cu_(x)O electrodes. Therefore, the optimized TiO_(2)/Cu_(x)O electrode results in the highest charge storing performance in the catholyte chamber, and the roles of vanadium redox species are also clearly demonstrated.

关键词： Photocatalyst Photoelectrochemical Copper oxide Charge recombination Redox pairs

Formation of interfacial brittle phases sigma phase and IMC in hybrid titanium-to-stainless steel joint

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Transactions of Nonferrous Metals Society of China 2011年第A01期21卷 7-11页

作者： Min Ku lee jung Gu Lee Jong Keuk lee Sung Mo HONG Sang Hoon lee Jin Ju PARK Jae Woo KIM Chang Kyu RHEE Nuclear Materials Research Division Korea Atomic Energy Research Institute Daejeon 305-353 Korea

The microstructures of the brazed joints for commercially pure Ti and stainless steel were investigated by the applications of various filler alloys including Ag-, Ti-, Zr- and Ni-based alloys. Generally, the dissimilar joints between Ti and stainless steel were dominated by the Ti-based intermetallic compounds (IMCs), e.g. (Ti, Zr)2(Fe, Ni), TiFe, TiCu, and Ti2(Fe, Ni), due to a significant dissolution of Ti from the base metal. The (Fe-Cr) σ phase was also observed near the stainless steel due to a segregation of Cr into the interface region. This research demonstrates empirically that the brittleness of the Ti and stainless steel joint can not be avoided only by applying single braze alloy or single insert metal, and thus an introduction of additional suitable interlayer between the filler alloy and the base metal is necessary to prevent the brittleness of the joint.

关键词：不锈钢脆性相钢接头界面区纯钛 IMC 金属间化合物镍基合金

An Effective Threat Detection Framework for Advanced Persistent Cyberattacks

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Computers, Materials & Continua 2023年第5期75卷 4231-4253页

作者： So-Eun Jeon Sun-Jin lee Eun-Young lee Yeon-Ji lee jung-Hwa Ryu jung-Hyun Moon Sun-Min Yi Il-gu lee Department of Future Convergence Technology Engineering Sungshin Women’s UniversitySeoul02844Korea Department of Convergence Security Engineering Sungshin Women’s UniversitySeoul02844Korea

Recently,with the normalization of non-face-to-face online environments in response to the COVID-19 pandemic,the possibility of cyberattacks through endpoints has increased.Numerous endpoint devices are managed meticulously to prevent cyberattacks and ensure timely responses to potential security threats.In particular,because telecommuting,telemedicine,and teleeducation are implemented in uncontrolled environments,attackers typically target vulnerable endpoints to acquire administrator rights or steal authentication information,and reports of endpoint attacks have been increasing considerably.Advanced persistent threats(APTs)using various novel variant malicious codes are a form of a sophisticated attack.However,conventional commercial antivirus and anti-malware systems that use signature-based attack detectionmethods cannot satisfactorily respond to such attacks.In this paper,we propose a method that expands the detection coverage inAPT attack environments.In this model,an open-source threat detector and log collector are used synergistically to improve threat detection performance.Extending the scope of attack log collection through interworking between highly accessible open-source tools can efficiently increase the detection coverage of tactics and techniques used to deal with APT attacks,as defined by MITRE Adversarial Tactics,Techniques,and Common Knowledge(ATT&CK).We implemented an attack environment using an APT attack scenario emulator called Carbanak and analyzed the detection coverage of Google Rapid Response(GRR),an open-source threat detection tool,and Graylog,an open-source log collector.The proposed method expanded the detection coverage against MITRE ATT&CK by approximately 11%compared with that conventional methods.

关键词： Advanced persistent threat cybersecurity endpoint security MITRE ATT&CK open-source threat detector threat log collector

Construction of tantalum/poly(ether imide)coatings on magnesium implants with both corrosion protection and osseointegration properties

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Bioactive Materials 2021年第4期6卷 1189-1200页

作者： Kwang-Hee Cheon Cheonil Park Min-Ho Kang In-gu Kang Min-Kyu lee Hyun lee Hyoun-Ee Kim Hyun-Do jung Tae-Sik Jang Department of Materials Science and Engineering Seoul National UniversitySeoulRepublic of Korea Department of Biomedical-Chemical Engineering Catholic University of KoreaBucheonGyeonggi-doRepublic of Korea Institute of Health Science Research Korea UniversitySeoul02841Republic of Korea Department of Materials Science and Engineering Chosun UniversityGwangjuRepublic of Korea

Poly(ether imide)(PEI)has shown satisfactory corrosion protection capability with good adhesion strength as a coating for magnesium(Mg),a potential candidate of biodegradable orthopedic implant material.However,its innate hydrophobic property causes insufficient osteoblast affinity and a lack of osseointegration.Herein,we modify the physical and chemical properties of a PEI-coated Mg implant.A plasma immersion ion implantation technique is combined with direct current(DC)magnetron sputtering to introduce biologically compatible tantalum(Ta)onto the surface of the PEI coating.The PEI-coating layer is not damaged during this process owing to the extremely short processing time(30 s),retaining its high corrosion protection property and adhesion stability.The Ta-implanted layer(roughly 10-nm-thick)on the topmost PEI surface generates long-term surface hydrophilicity and favorable surface conditions for pre-osteoblasts to adhere,proliferate,and differentiate.Furthermore,in a rabbit femur study,the Ta/PEI-coated Mg implant demonstrates significantly enhanced bone tissue affinity and osseointegration capability.These results indicate that Ta/PEI-coated Mg is promising for achieving early mechanical fixation and long-term success in biodegradable orthopedic implant applications.

关键词： Magnesium Tantalum Poly(ether imide) Bio-functionalized coating Biodegradable orthopedic implants

Gyejibokryeong-Hwan improves recovery of injured muscles in mouse model of muscle contusion

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Journal of Traditional Chinese Medicine 2021年第3期41卷 406-413页

作者： Chi Ho lee Jeong June Choi Joo Hye Sim Younmin Shin Seung-Joon Oh Ji-Hyang gu Hyun Ju Ha Dong Hwi Jeon Eun-jung lee Min-Seok Oh Department of Korean Medicine Rehabilitation College of Korean MedicineDaejeon UniversityDaejeon 34520Republic of Korea Laboratory of Molecular Medicine College of Korean MedicineDaejeon UniversityDaejeon 34520Republic of Korea

OBJECTIVE: To investigate the effects of Gyejibokryeong-Hwan(guizhifuling-wan, GBH) on muscle injury in a mouse model of muscle contusion.METHODS: C57/BL6 mouse biceps femoris muscles were injured using the drop-mass method and injured animals were treated orally with GBH(50,100, or 500 mg/kg) once a day for 7 d. Open field and treadmill running tests were performed to assess functional recovery from muscle injury. The production of pro-inflammatory cytokines was examined by enzyme-linked immunosorbent assay and Western blotting analysis. Expression of the muscle regeneration biomarkers, myoblast determination(Myo D), myogenic factor 5(Myf5), and smooth muscle actin(α-SMA), in the biceps femoris muscle was investigated at the protein and m RNA level by Western blotting and real time-PCR, respectively. Histological analysis was performed using hematoxylin and eosin staining. Finally, myosin heavy chain production was investigated in differentiated C2C12 myoblasts in the presence of GBH.RESULTS: GBH treatment markedly improved locomotion and running behavior. GBH significantly inhibited the secretion of monocyte chemoattractant protein-1 into the bloodstream in muscle-contused animals. The levels of Myo D, Myf5, and α-SMA protein and m RNA were significantly up-regulated by GBH in injured muscle tissue. Histological studies suggested that GBH facilitated recovery from muscle damage. However, GBH did not induce the production of myosin heavy chain in vitro.CONCLUSION: Overall, the present study suggested that GBH improves the recovery of the injured muscles in the mouse model of muscle contusion.

关键词： muscles wounds and injuries contusions regeneration muscle skeletal myogenic regulatory factor 5 Gyejibokryeong-Hwan

Effect of focal laser photocoagulation in eyes with mild to moderate non-proliferative diabetic retinopathy

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International Journal of Ophthalmology(English edition) 2016年第10期9卷 1439-1443页

作者： Seong Hun Jeong jung Il Han Sung Won Cho Dong Won lee Chul gu Kim Tae Gon lee Jong Woo Kim Department of Ophthalmology Kim's Eye HospitalMyung-Gok Eye Research InstituteKonyang University College of Medicine

AIM：To report the effect of focal laser photocoagulation on both the severity of hard exudates（HEs） and the rate of disease progression in eyes with mild to moderate non-proliferative diabetic retinopathy（NPDR）.METHODS： We retrospectively reviewed the medical records of 33 patients（60 eyes） who had been diagnosed with mild to moderate NPDR between January 2006 and December 2012.The patients were divided into 2 groups：Group A（38 eyes in 20 patients treated using focal laser photocoagulation） and Group B（treated without laser photocoagulation）.We also reviewed the best corrected visual acuity measurements,and the fundus photographs taken at both baseline and follow-up visits. RESULTS： In Group A,HE severity grade had decreased significantly from baseline to the final visit（P 〈0.05）,but this was not the case in Group B（P =0.662）.The cumulative probabilities of retinopathy progression at 5y were 26% in Group A and 30% in Group B.KaplanMeier survival curves showed no significant difference between the groups with regard to retinopathy progression（P =0.805）.CONCLUSION： Focal laser photocoagulation reduced the levels of HEs in eyes with mild to moderate NPDR.However,the treatment was not able to decelerate the progression of DR.

关键词： focal laser diabetic retinopathy retina non-proliferative diabetic retinopathy

Functional Materials and Innovative Strategies for Wearable Thermal Management Applications

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Nano-Micro Letters 2023年第9期15卷 562-603页

作者： Yeongju jung Minwoo Kim Taegyeom Kim Jiyong Ahn Jinwoo lee Seung Hwan Ko Applied Nano and Thermal Science Lab Department of Mechanical EngineeringSeoul National University1 Gwanak-roGwanak-guSeoul 08826South Korea Department of Mechanical Roboticsand Energy EngineeringDongguk University30 Pildong-ro 1-gilJung-guSeoul 04620South Korea Institute of Advanced Machinery and Design(SNU-IAMD) Seoul National UniversityGwanak-roGwanak-guSeoul 08826South Korea Institute of Engineering Research Seoul National University1 Gwanak-roGwanak-guSeoul 08826South Korea

Thermal management is essential in our body as it affects various bodily functions,ranging from thermal discomfort to serious organ failures,as an example of the worst-case scenario.There have been extensive studies about wearable materials and devices that augment thermoregulatory functionalities in our body,employing diverse materials and systematic approaches to attaining thermal homeostasis.This paper reviews the recent progress of functional materials and devices that contribute to thermoregulatory wearables,particularly emphasizing the strategic methodology to regulate body temperature.There exist several methods to promote personal thermal management in a wearable form.For instance,we can impede heat transfer using a thermally insulating material with extremely low thermal conductivity or directly cool and heat the skin surface.Thus,we classify many studies into two branches,passive and active thermal management modes,which are further subdivided into specific strategies.Apart from discussing the strategies and their mechanisms,we also identify the weaknesses of each strategy and scrutinize its potential direction that studies should follow to make substantial contributions to future thermal regulatory wearable industries.

关键词： Thermal management Passive heat transfer Active heat transfer Wearable materials Wearable device