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Journal of Materials Science & Technology 2022年第16期111卷 99-110页

作者： Vioni Dwi Sartika won seok choi Gwanghyo choi Jaewook Han Sung-Jin Chang won-seok Ko Blazej Grabowski Pyuck-Pa choi Department of Materials Science and Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea Gangwon Regional Division Korea Institute of Industrial TechnologyGangwon 25440Republic of Korea Division of Measurement and Analysis National Nanofab CenterDaejeon 34141Republic of Korea School of Materials Science and Engineering University of UlsanUlsan 44610Republic of Korea Institute for Materials Science University of StuttgartPfaffenwaldring 5570569 StuttgartGermany

We report laser cladding of pure titanium on a CoCrMo alloy using directed energy *** electron microscopy,the microstructural evolution upon varying the process parameters,especially laser power and powder feed rate,was investigated in relation to crack *** layers showing dilution rates of more than 5%contained cracks due to the formation of the brittle Co_(2)Ti intermetallic *** observed cracks could be ascribed to a mismatch in thermal expansion and a resulting stress of more than 440 MPa acting on the Co_(2)Ti phase,as determined by density functional theory and ***,an excess laser energy caused chemical inhomogeneity and unmelted Ti powder particles,while a deficient laser energy resulted in a lack of *** cracks nor partially melted powders were observed for a powder feed rate of 3 g/min and a laser power of 225–300 W,for which the dilution rate was minimized to less than 5%.For such samples,the cladding layers comprised pureα-Ti and a uniform CoT i interface with Co_(2)Ti islands.

关键词： Additive manufacturing Dissimilar metal joining Titanium Cobalt-based alloy

Decomposition behavior of yttria-stabilized zirconia and its effect on directed energy deposited Ti-based composite material

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Journal of Materials Science & Technology 2022年第17期112卷 138-150页

作者： Gwanghyo choi won seok choi Yoon Sun Lee Dahye Kim Ji Hyun Sung Seungjun An Chang-seok Oh Amine Hattal Madjid Djemai Brigitte Bacroix Guy Dirras Pyuck-Pa choi Department of Materials Science and Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea 3D Additive Manufacturing Application Tech.Center Korea Institute of Industrial TechnologyDaegu 42994Republic of Korea InssTek Co. Daejeon 04763Republic of Korea Korea Institute of Materials Science 797 ChangwondaeroChangwon 51508Republic of Korea UniversitéSorbonne Paris Nord Laboratoire des Sciences des Procédés et des MatériauxLSPMCNRSUPR 3407F-93430VilletaneuseFrance Z3Dlab Parc Technologique26 Rue des SablonsMontmagny 95360France CNRS UPR3407Laboratoire des Sciences des Procédés et des MatériauxLSPMUniversitéSorbonne Paris NordF-93430VilletaneuseFrance

We report on the microstructure and the strengthening mechanisms of additively manufactured parts fabricated by directed energy deposition of Ti-6Al-4V(Ti64)powders blended with yttria-stabilized zirconia(YSZ)*** specimens showed refined microstructures as compared to bare as-deposited Ti64,where theαand columnar priorβgrain sizes decreased with increasing YSZ *** YSZ nanoparticles decomposed during the deposition process and led to the formation of yttrium oxide and some excess oxygen in the Ti64 *** decrease in the sizes of the priorβgrains could be attributed to the increasing amount of dissolved oxygen and yttrium,which promoted constitutional ***,the reduction in the size of theαgrains could be ascribed to a shift of the onset of theβ→α+βtransformation to a higher temperature and shorter time with increasing concentration of dissolved ***,the contributions of the underlying strengthening mechanisms for the as-deposited specimens were quantitatively determined.

关键词： Additive manufacturing Directed energy deposition Metal matrix composites Titanium alloys Yttrium-stabilized zirconia

Adaptive Step Size Control of LMS-based Interference Cancellation for ICS Repeater in Wibro Environment

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Journal of Measurement Science and Instrumentation 2010年第1期1卷 98-102页

作者： Jeong-gon KIM won-geon BAE won-seok choi Dept.of Electronic Engineering Korea Polytechnic UniversityKyunggi-Do 429-793Korea

The use of repeater for the support of high rate data trans- mission and the extension of cell coverage is imperative for the Wibro system, which based on the IEEE 802.16e standardization. Generally, if the separation between transmitting and receiving antennas is not sufficient, the oscillation of repeater and the interference due to the feedback signals from original transmitted signal may be oectLrr. Hence, the Interference Cancellation System （ICS） should be implemented as the important part of the repeater system for the mobile cellular systems in order to eliminate unwanted signals from the corrupted signals in the receiver. In this paper, we propose an adaptive technique for the Least Mean Square（LMS）-based interference cancellation methods by changing the step size according to the variation of channel envirorauent in onter to improve the performance degradation which occta-rs by using the fixed step size approach. Simulation results show that the proposed scheme attains a little lower Ber Error Rate（BER） performance and much faster convergence speed compared to the conventional LMS-based interference cancellation techniques. The proposed scheme can be applied to other Orthogonal Frequency Division Multiple（OFDM）-based cellular systenas and also be expected to achieve a similar performance improvement to IMT-advanced system, which is called as the next generation mobile communication standards.

关键词： Wibro mobile communication repeater adaptive inter-ference cancellation

Comparison of computed tomography findings between bacteremic and non-bacteremic acute pyelonephritis due to Escherichia coli

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World Journal of Radiology 2016年第4期8卷 403-409页

作者： Seon Jung Oh Bo-Kyung Je Seung Hwa Lee won seok choi Doran Hong Sung-Bum Kim Department of Radiology Korea University Hospital Department of Internal Medicine Korea University Hospital Department of Internal Medicine B-um Hospital

AIM:To identify computed tomography(CT)findings that are associated with the presence of bacteremia in patients with acute pyelonephritis(APN)due to Escherichia coli(***).METHODS:The clinical data and contrast-enhanced CT findings of 128 patients who were diagnosed with APN due to *** and showed renal abnormality on contrast-enhanced CT between January 2003 and November 2013 were retrospectively *** patients were divided into two groups according to the presence of bacteremia:The bacteremia group and the non-bacteremia *** abnormality on contrast-enhanced CT were categorized into 5 renal and 4 extrarenal CT findings and compared between the two groups using the χ~2 test and multivariate logistic ***:Among the 128 patients,34 patients(26.6%)were classified into the bacteremia group and 94 patients(73.4%)into the non-bacteremia *** was no statistically significant difference in gender between the two groups(P = 0.09),but the age of thepatients in the bacteremia group was higher than that of the patients in the non-bacteremia group(P < 0.01).Compared to the non-bacteremia group,1 renal CT finding such as urothelial thickening and 3 extrarenal CT findings such as diffuse peritoneal thickening,cystitis and pulmonary congestion were more frequently observed in the bacteremia group with statistical *** logistic regression analysis revealed that CT findings,including urothelial thickening,diffuse peritoneal thickening,cystitis and pulmonary congestion were suggested as the predictive CT findings of bacteremic ***:On CT,urothelial thickening,diffuse peritoneal thickening,cystitis,and pulmonary congestion are more frequently observed in patients with bacteremic APN due to ***.

关键词： Escherichia coli Pyelonephritis Urinary tract infections Bacteremia Multidetector computed tomography

Apolipoprotein A-I binding protein-mediated neuroprotection in glaucomatous neuroinflammation and neurodegeneration

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Neural Regeneration Research 2025年第5期20卷 1414-1415页

作者： Sinwoo Hwang Seunghwan choi Soo-Ho choi Keun-Young Kim Yury I.Miller won-Kyu Ju Hamilton Glaucoma Center and Shiley Eye Institute The Viterbi Family Department of OphthalmologyUniversity of California San DiegoLa JollaCAUSA Department of Medicine University of California San DiegoLa JollaCAUSA National Center for Microscopy and Imaging Research Department of NeurosciencesUniversity of California San DiegoLa JollaCAUSA

Glaucoma is a multifactorial eye disorder that can cause vision loss and irreversible blindness,affecting individ uals aged 40 to 80 yea rs *** to the aging population,it is expected that the number of people affected by glaucoma will surpass 111 million by 2040 as the disease becomes more *** primarily contributes to optic nerve axon loss and the progressive degeneration of retinal ganglion cells (RGCs),subsequently leading to vision impairment.

关键词： irreversible pass primarily

Role of kaempferol to increase bioavailability and pharmacokinetics of nifedipine in rats

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Chinese Journal of Natural Medicines 2019年第9期17卷 690-697页

作者： PARK Ji-won choi Jin-seok Hazardous Substances Analysis Division Gwangju Regional Office of Food and Drug SafetyGwangju 61012Republic of Korea Department of Medical Management Chodang UniversityJeollanam-do 58530Republic of Korea

Herein,the purpose of this study is to evaluate the effects of kaempferol on bioavailability and pharmacokinetics of nifedipine and its metabolite dehydronifedipine in *** experimental design is based on with or without kaempferol in the oral and intravenous administration of nifedipine in ***,the pharmacokinetic parameters including nifedipine and dehydronifedipine were evaluated in *** in vitro studies of kaempferol were investigated on P-glycoprotein(P-gp)and cytochrome P450(CYP)3A4 *** reduced a 50%inhibitory concentration(IC50)of 8.6μmol·L-1 on CYP3A4 enzyme ***,kaempferol clearly improved the cell internalization of rhodamine-123 in MCF-7/ADR cells overexpressing *** on increased concentrations of kaempferol,the areas under the plasma concentration–time curve(AUC0-∞)and the peak concentration(Cmax)of nifedipine were increased after oral and intravenous ***,the absolute bioavailability(AB)and relative bioavailability(RB)of nifedipine in the presence of kaempferol was significantly higher than those of the control group after oral and intravenous *** of bioavailability of nifedipine by kaempferol may be mainly because of the inhibition of the P-gp-mediated efflux transporter in the small intestine and CYP3A4-mediated metabolism in the small intestine or liver,or both.

关键词： Nifedipine Kaempferol CYP3A4 P-gp Pharmacokinetics Bioavailability

Therapeutic potential of exercise-hormone irisin in Alzheimer's disease

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Neural Regeneration Research 2025年第6期20卷 1555-1564页

作者： Eunhee Kim Rudolph ETanzi Se Hoon choi Genetics and Aging Research Unit MassGeneral Institute for Neurodegenerative DiseaseDepartment of NeurologyMassachusetts General HospitalHarvard Medical SchoolCharlestownMAUSA McCance Center for Brain Health Massachusetts General HospitalBostonMAUSA

Irisin is a myokine that is generated by cleavage of the membrane protein fibronectin type Ⅲ domain-containing protein 5(FNDC5) in response to physical exercise. Studies reveal that irisin/FNDC5 has neuroprotective functions against Alzheimer's disease, the most common form of dementia in the elderly, by improving cognitive function and reducing amyloid-β and tau pathologies as well as neuroinflammation in cell culture or animal models of Alzheimer's disease. Although current and ongoing studies on irisin/FNDC5 show promising results, further mechanistic studies are required to clarify its potential as a meaningful therapeutic target for alleviating Alzheimer's disease. We recently found that irisin treatment reduces amyloid-β pathology by increasing the activity/levels of amyloid-β-degrading enzyme neprilysin secreted from astrocytes. Herein, we present an overview of irisin/FNDC5's protective roles and mechanisms against Alzheimer's disease.

关键词： Alzheimer's disease exercise fibronectin typeⅢdomain-containing protein 5(FNDC5) irisin

Reaction mechanism and additional lithium storage of mesoporous MnO_(2) anode in Li batteries

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Journal of Energy Chemistry 2021年第2期30卷 276-284,I0010页

作者： Jaesang Yoon Woosung choi Taewhan Kim Hyunwoo Kim Yun seok choi Ji Man Kim won-Sub Yoon Department of Energy Science Sungkyunkwan UniversitySuwon 16419South Korea Department of Chemistry Sungkyunkwan UniversitySuwon 16419South Korea

Nanostructured transition metal oxides,employed as anode materials for lithium-ion batteries,exhibit a higher capacity than the theoretical capacity based on the conversion *** date,the reasons behind this phenomenon are *** the one-step evolution of anode material for lithium-ion batteries,it is essential to understand the lithium storage reaction mechanism of the anode ***,we provide a detailed report on the lithium storage and release mechanism of MnO2,using synchrotron-based X-ray techniques.X-ray diffraction and X-ray absorption spectroscopy results indicate that during the first discharge,MnO2 is reduced in the order of MnO2→LixMnO2(1

关键词： Mesoporous MnO_(2) Reaction mechanism Electrolyte-derived surface layer Synchrotron-based X-ray techniques Anode Li battery

Acute and chronic excitotoxicity in ischemic stroke and late-onset Alzheimer's disease

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Neural Regeneration Research 2025年第7期20卷 1981-1988页

作者： Shan Ping Yu Emily choi Michael QJiang Ling Wei Department of Anesthesiology Emory University School of MedicineAtlantaGAUSA Center for Visual and Neurocognitive Rehabilitation Atlanta Veterans Affairs Medical CenterDecaturGAUSA

Stroke and Alzheimer's disease are common neurological disorders and often occur in the same *** comorbidity of the two neurological disorders represents a grave health threat to older *** review presents a brief background of the development of novel concepts and their clinical *** activity of glutamatergic N-methyl-D-aspartate receptors and N-methyl-D-aspartate receptor-mediated Ca^(2+)influx is critical for neuronal *** ischemic insult induces prompt and excessive glutamate release and drastic increases of intracellular Ca^(2+)mainly via N-methyl-D-aspartate receptors,particularly of those at the extrasynaptic *** Ca^(2+)-evoked neuronal cell death in the ischemic core is dominated by necrosis within a few hours and days known as acute ***,mild but sustained Ca^(2+)increases under neurodegenerative conditions such as in the distant penumbra of the ischemic brain and early stages of Alzheimer's disease are not immediately toxic,but gradually set off deteriorating Ca^(2+)-dependent signals and neuronal cell loss mostly because of activation of programmed cell death *** on the Ca^(2+)hypothesis of Alzheimer's disease and recent advances,this Ca^(2+)-activated“silent”degenerative excitotoxicity evolves from years to decades and is recognized as a unique slow and chronic *** N-methyl-D-aspartate receptor subunit GluN3A,primarily at the extrasynaptic site,serves as a gatekeeper for the N-methyl-D-aspartate receptor activity and is neuroprotective against both acute and chronic *** stroke and Alzheimer's disease,therefore,share an N-methyl-D-aspartate receptor-and Ca^(2+)-mediated mechanism,although with much different time *** is thus proposed that early interventions to control Ca^(2+)homeostasis at the preclinical stage are pivotal for individuals who are susceptible to sporadic late-onset Alzheimer's disease and Alzheimer's disease-related

关键词： Ca^(2+)hypothesis cognitive deficits hyperactivity late-onset Alzheimer's disease neurodegeneration N-methyl-D-aspartate receptors N-methyl-D-aspartate receptor subunits pathogenesis preventive treatment