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Replica higher-order topology of Hofstadter butterflies in twisted bilayer graphene

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npj Computational Materials 2023年第1期9卷 783-791页

作者： Sun-woo kim Sunam Jeon Moon Jip Park Youngkuk kim Department of Physics KAISTDaejeonRepublic of Korea Department of Materials Science and Metallurgy University of CambridgeCambridgeUK Department of Energy Science Sungkyunkwan UniversitySuwonRepublic of Korea Center for Theoretical Physics of Complex Systems Institute for Basic Science(IBS)DaejeonRepublic of Korea Department of Physics Hanyang UniversitySeoulRepublic of Korea Department of Physics Sungkyunkwan UniversitySuwonRepublic of Korea

The Hofstadter energy spectrum of twisted bilayer graphene(TBG)is found to have recursive higher-order topological *** demonstrate that higher-order topological insulator(HOTI)phases,characterized by localized corner states,occur as replicas of the original HOTIs to fulfill the self-similarity of the Hofstadter *** show the existence of exact flux translational symmetry in TBG at all commensurate *** on this result,we identify that the original HOTI phase at zero flux is re-entrant at a half-flux periodicity,where the effective twofold rotation is *** addition,numerous replicas of the original HOTIs are found for fluxes without protecting *** the original HOTIs,replica HOTIs feature both localized corner states and edge-localized real-space topological *** replica HOTIs originate from the different interaction scales,namely,intralayer and interlayer couplings,in *** topological aspect of Hofstadter butterflies revealed in our results highlights symmetry-protected topology in quantum fractals.

关键词： properties spectrum topological

Mending the broken in amyotrophic lateral sclerosis: DNA damage and repair in motor neuron degeneration

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Neural Regeneration Research 2021年第1期16卷 104-105页

作者： Byung woo kim Lee J.Martin Department of Pathology Division of Neuropathologythe Pathobiology Graduate Training ProgramJohns Hopkins University School of MedicineBaltimoreMDUSA Department of Neuroscience Johns Hopkins University School of MedicineBaltimoreMDUSA

Amyotrophic lateral sclerosis(ALS)is a fatal neurodegenerative disease that causes paralysis and respiratory failure(Petrov et al.,2017).The driving mechanisms are unknown,and there are no effective treatments(Petrov et al.,2017).Aging and a few gene mutations,a common one being missense mutations in superoxide dismutase-1(SOD1),are risk factors for ALS(Figure 1).The recent Food and Drug Administration approval of edaravone for the treatment of ALS putatively supports a role for oxidative and nitrative stresses in the disease processes(Figure 1A).DNA damage,abnormalities in DNA repair,and other nuclear abnormalities are implicated also in the pathogenesis of human ALS(Bradley and Krasin,1982;kim et al.,2020).

关键词： al. damage degeneration

Effect of ammonia gas etching on growth of vertically aligned carbon nanotubes/nanofibers

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Transactions of Nonferrous Metals Society of China 2011年第A1期21卷 130-134页

作者： Sang-Gook kim Sooh-Yung kim Hyung-woo LEE Department of Mechanical Engineering Massachusetts Institute of Technology 77 Massachusetts Ave Cambridge MA 02139 USA National Core Research Center for Hybrid Materials Solution Pusan National University

The etching effect of ammonia （NH3） on the growth of vertically aligned nanotubes/nanofibers （CNTs） was investigated by direct-current plasma enhanced chemical vapor deposition （DC-PECVD）. NH3 gas etches Ni catalyst layer to form nanoscale islands while NH3 plasma etches the deposited amorphous carbon. Based on the etching effect of NH3 gas on Ni catalyst, the differences of growing bundles of CNTs and single strand CNTs were discussed; specifically, the amount of optimal NH3 gas etching is different between bundles of CNTs and single strand CNTs. In contrast to the CNT carpet growth, the single strand CNT growth requires shorter etching time （5 min） than large catalytic patterns （10 rain） since nano dots already form catalyst islands for CNT growth. Through removing the plasma pretreatment process, the damage from being exposed at high temperature substrate occurring during the plasma generation time is minimized. High resolution transmission electron microscopy （HTEM） shows fishbone structure of CNTs grown by PECVD.

关键词： carbon nanotube ammonia etching nickel catalyst plasma enhanced chemical vapor deposition (PECVD)

3D designed battery-free wireless origami pressure sensor

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Microsystems & Nanoengineering 2022年第6期8卷 35-46页

作者： Taeil kim Amirhossein Hassanpoor Kalhori Tae-Ho kim Chao Bao woo Soo kim Additive Manufacturing Laboratory School of Mechatronic Systems EngineeringSimon Fraser UniversitySurrey V3T 0A3 BCCanada

A pressure monitoring structure is a very useful element for a wearable device for health monitoring and sports *** pressure sensors have been studied extensively,battery-free functions working in wireless detection have not been studied ***,we report a 3D-structured origami-based architecture sensor for wireless pressure *** developed an architectured platform for wireless pressure sensing through inductorcapacitor(LC)sensors and a monopole antenna.A personalized smart insole with Miura-ori origami designs has been 3D printed together with conductive 3D printed sensors *** monitoring of resonant frequency and intensity changes of LC sensors have been demonstrated to monitor foot pressure for different *** sensitivity of the wireless pressure sensor is tunable from 15.7 to 2.1 MHz/kPa in the pressure ranges from 0 to 9 kPa and from 10 to 40 kPa,*** proposed wireless pressure-sensing platform can be utilized for various applications such as orthotics,prosthetics,and sports gear.

关键词： battery free utilized

High-power and long-life supercapacitive performance of hierarchical, 3-D urchin-like W18049 nanostructure electrodes

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Nano Research 2016年第3期9卷 633-643页

作者： Sangbaek Park Hyun-woo Shim Chan woo Lee Hee Jo Song Jae-Chan kim Dong-Wan kim Department of Materials Science and Engineering Seoul National University Seoul 151-744 Republic of Korea School of Civil Environmental and Architectural Engineering Korea University Seou1136-713 Republic of Korea

We report the facile, one-pot synthesis of 3-D urchin-like W18O49 nanostructures （U-WO） via a simple solvothermal approach. An excellent supercapacitive performance was achieved by the U-WO because of its large Brunauer-Emmett- Teller （BET） specific surface area （ca. 123 m2.g-1） and unique morphological and structural features. The U-WO electrodes not only exhibit a high rate-capability with a specific capacitance （Csp） of -235 F·g-1 at a current density of 20 A.g-1, but also superior long-life performance for 1,000 cycles, and even up to 7,000 cycles, showing -176 F·g-1 at a high current density of 40 A.g-1.

关键词： hierarchical structure W18O49 high-power long cycle life supercapacitor

Development and application of a multi-step porcine in vitro system to evaluate feedstuffs and feed additives for their efficacy in nutrient digestion, digesta characteristics, and intestinal immune responses

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Animal Nutrition 2024年第2期17卷 265-282页

作者： Hee Yeon kim Jun-Ok Moon Sung woo kim Application Center CJ Blossom Park Department of Animal Science North Carolina State University

In vitro model provides alternatives to the use of live animals in research. In pig nutrition, there has been a tremendous increase in in vivo research over the decades. Proper utilization of in vitro models could provide a screening tool to reduce the needs of in vivo studies, research duration, cost, and the use of animals and feeds. This study aimed to develop a multi-step porcine in vitro system to simulate nutrient digestion and intestinal epithelial immune responses affected by feedstuffs and feed additives. Seven feedstuffs(corn, corn distillers dried grains with solubles [corn DDGS], barley, wheat, soybean meal, soy protein concentrates, and Corynebacterium glutamicum cell mass [CGCM]), feed enzymes(xylanase and phytase), and supplemental amino acids(arginine, methionine, and tryptophan), were used in this in vitro evaluation for their efficacy on digestibility, digesta characteristics, and intestinal health compared with the results from previously published in vivo studies. All in vitro evaluations were triplicated. Data were analyzed using Mixed procedure of SAS9.4. Evaluations included(1) nutrient digestibility of feedstuffs,(2) the effects of feed enzymes, xylanase and phytase, on digestibility of feedstuffs and specific substrates, and(3) the effects of amino acids, arginine, tryptophan, and methionine, on anti-inflammatory, anti-oxidative, and anti-heat stress statuses showing their effects(P < 0.05) on the measured items. Differences in dry matter and crude protein digestibility among the feedstuffs as well as effects of xylanase and phytase were detected(P < 0.05), including xylo-oligosaccharide profiles and phosphorus release from phytate. Supplementation of arginine, tryptophan, and methionine modulated(P < 0.05) cellular inflammatory and oxidative stress responses. The use of this in vitro model allowed the use of 3 experimental replications providing sufficient statistical power at P < 0.05. This indicates in vitro models can have increased prec

关键词： Digestion Feed additive Feedstuff In vitro Intestine Pig

Pear pomace water extract reduces adiposity in vivo and in vitro by activating the AMPK-dependent pathway

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Asian Pacific Journal of Tropical Biomedicine 2020年第5期10卷 208-215页

作者： Mi-Kyoung You gwang-woong Go Hwa-Jin kim Jin Rhyu Hyeon-A kim Department of Nutrition and Health Sciences University of NebraskaLincolnNEUSA Department of Food and Nutrition Hanyang UniversitySeoulRepublic of Korea Department of Food and Nutrition Mokpo National UniversityJeollanam-doRepublic of Korea

Objective: To explore the inhibitory effect of water extract from pear pomace on abdominal fat accumulation and its underlying mechanism in high fat diet-fed animals. Methods: Three groups of male C57 BL/6 J mice were fed with a 60% kcal fat diet for 8 weeks. Pear pomace water extract(200 or 400 mg/kg body weight) was administered once daily via oral gavage. To confirm the possibility of the water extract of pear pomace acting as an activator of adenosine 5’-monophosphateactivated protein kinase(AMPK), differentiation of 3 T3-L1 preadipocytes was induced in the presence of the water extract of pear pomace with or without compound C. Body weight, food efficacy ratio, insulin resistance, and adipogenic protein expression were measured. Moreover, in the 3 T3-L1 cells, lipid content and lipogenesis-related proteins were measured using Oil Red O staining and Western blotting ***: Body weight gain and total abdominal fat weight were reduced in mice treated with pear pomace water extract. Pear pomace water extract reduced fasting blood glucose and insulin, thereby reducing the homeostatic model assessment of insulin resistance. It also resulted in dose-dependent decreases in triglyceride, total cholesterol, and low-density lipoproteincholesterol. The protein expression of p-AMPK increased, while the expression of AMPK-downstream proteins including PPAR-γ, C/EBPα, SREBP-1 c, ACC, and FAS decreased in the adipose tissue of mice treated with pear pomace water extract. Furthermore, the inhibition of AMPK by compound C blocked pear pomace water extract-induced reduction of lipid content and the expression of lipogenesis-related genes. Conclusions: Pear pomace water extract prevents fat accumulation both in vivo and in vitro by activating AMPK.

关键词： Pear pomace AMPK Compound C Obesity Insulin resistance

Recent advances in chemotherapy for advanced gastric cancer

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World Journal of Gastrointestinal Oncology 2010年第7期2卷 287-294页

作者： Jong gwang kim Ho Young Chung Wansik Yu Department of Oncology/Hematology Kyungpook National University Hospital Kyungpook National University School of Medicine Department of Surgery Kyungpook National University Hospital

Although medical treatment has been shown to improve quality of life and prolong survival,no significant progress has been made in the treatment of advanced gastric cancer(AGC)within the last two ***,the choice of optimum standard first-line chemotherapy regimen for AGC remains debatable,and most responses to chemotherapy are partial and of short duration,with a median survival of approximately 7-11 mo and survival at 2 years rarely more than 10%.Recently,remarkable progress in tumor biology has led to the development of new agents that target critical aspects of oncogenic *** AGC,several molecular targeting agents are now under evaluation in international randomized studies,and trastuzumab,an anti-HER2 monoclonal antibody,has shown antitumor activity against HER-2 positive ***, this benefit is limited to only about 20%of patients with AGC(patients with HER-2 positive AGC).Therefore,there remains a critical need for both the development of more effective agents and the identification of predictive and prognostic molecular markers to select those patients who will benefit most from specific chemotherapeutic regimens and targeted therapies.

关键词： Gastric cancer Prognosis Chemotherapy Cytotoxic agents Targeted agents

Lesion localization of global aphasia without hemiparesis by overlapping of the brain magnetic resonance images

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Neural Regeneration Research 2014年第23期9卷 2081-2086页

作者： woo Jin kim Nam-Jong Paik Department of Rehabilitation Medicine Seoul National University Bundang Hospital Department of Physical Medicine and Rehabilitation Haeundae Paik Hospital Inje University of Medicine Department of Rehabilitation Medicine Seoul National University College of Medicine

Global aphasia without hemiparesis is a striking stroke syndrome involving language impairment without the typically manifested contralateral hemiparesis, which is usually seen in patients with global aphasia following large left perisylvian lesions. The objective of this study is to elucidate the specific areas for lesion localization of global aphasia without hemiparesis by retrospectively studying the brain magnetic resonance images of six patients with global aphasia without hemiparesis to define global aphasia without hemiparesis-related stroke lesions before overlapping the images to visualize the most overlapped area. Talairach coordinates for the most overlapped areas were converted to corresponding anatomical regions. Lesions where the images of more than three patients overlapped were considered significant. The overlapped global aphasia without hemiparesis related stroke lesions of six patients revealed that the significantly involved anatomi- cal lesions were as follows： frontal lobe, sub-gyral, sub-lobar, extra-nuclear, corpus callosum, and inferior frontal gyrus, while caudate, claustrum, middle frontal gyrus, limbic lobe, temporal lobe, superior temporal gyrus, uncus, anterior cingulate, parahippocampal, amygdala, and subcallosal gyrus were seen less significantly involved. This study is the first to demonstrate the heterogeneous anatomical involvement in global aphasia without hemiparesis by overlapping of the brain magnetic resonance images.

关键词： nerve regeneration global aphasia without hemiparesis global aphasia stroke hemiparesis brain magnetic resonance imaging neural regeneration