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Comparative study of chitosan/fibroin–hydroxyapatite and collagen membranes for guided bone regeneration in rat calvarial defects: micro-computed tomography analysis

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International Journal of Oral Science 2014年第2期6卷 87-93页

作者： jae Min Song Sang Hun Shin Yong Deok Kim jae Yeol lee Young jae Baek Sang Yong Yoon Hong Sung Kim Department of Oral and Maxillofacial Surgery School of Dentistry Pusan National University Yangsan Korea Department of Biomaterial Science Pusan National University Miryang Korea

This study aimed to utilize micro-computed tomography （micro-CT） analysis to compare new bone formation in rat calvarial defects using chitosan/fibroin-hydroxyapatite （CFB-HAP） or collagen （Bio-Gide） membranes. Fifty-four （54） rats were studied. A circular bony defect （8 mm diameter） was formed in the centre of the calvaria using a trephine bur. The CFB-HAP membrane was prepared by thermally induced phase separation. In the experimental group （n= 18）, the CFB-HAP membrane was used to cover the bony defect, and in the control group （n= 18）, a resorbable collagen membrane （Bio-Gide） was used. In the negative control group （n= 18）, no membrane was used. In each group, six animals were euthanized at 2, 4 and 8 weeks after surgery. The specimens were then analysed using micro-CT. There were significant differences in bone volume （BV） and bone mineral density （BMD）（P〈O.05） between the negative control group and the membrane groups. However, there were no significant differences between the CFB-HAP group and the collagen group. We concluded that the CFB-HAP membrane has significant potential as a guided bone regeneration （GBR） membrane.

关键词： chitosan/fibroin-hydroxyapatite collagen membrane guided bone regeneration micro-computed tomography rat calva rial defect

Partial Oxidation of Methane with Sol-Gel Fe/Hf/YSZ Catalyst in Dielectric Barrier Discharge: Catalyst Activation by Plasma

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Journal of Rare Earths 2006年第5期24卷 513-518页

作者： Antonius Indarto jae-Wook Choi Hwaung lee Hyung Keun Song Jelliarko Palgunadi Clean Technology Research Center Korea Institute of Science and Technology KoreaDepartment of Chemical and Biological Engineering Korea University Korea Clean Technology Research Center Korea Institute of Science and Technology Korea Hydrogen Energy Research Center Korea Institute of Science and Technology Korea

A 1% Fe-30% Hf over yttria-stabilized zirconia catalyst in combination with novel plasma-assisted activation techniques for a direct partial oxidation of methane to methanol was tested using dielectric barrier discharge plasma at ambient temperature and atmospheric pressure. However, instead of methanol, the reaction products were dominated by HE, CO, CO2, C2, and H2O. A catalytically activated plasma process increased the production of methanol compared with a noncatalytic plasma process. The maximum selectivity of methanol production was achieved using a catalyst that was treated at higher applied power.

关键词： methane oxidation dielectric barrier discharge catalyst plasma activation rare earths

Effect of Sub-T_g Annealing on the Corrosion Resistance of the Cu–Zr Amorphous Alloys

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Acta Metallurgica Sinica(English Letters) 2018年第3期31卷 273-280页

作者： Sang-Soo Shin Hong-Kyu Kim jae-Chul lee Ik-Min Park Department of Materials Science and Engineering Pusan National University Advanced Analysis Center Korea Institute of Science and Technology Department of Materials Science and Engineering Korea University

Despite the economy of material cost and excellent toughness of Cu-based amorphous alloys,especially CusoZrso,their poor corrosion resistance to a chloride medium limits their widespread *** this study,corrosion tests were performed on the CusoZrso amorphous alloy with different degrees of short-range order,which were prepared by annealing below the glass transition temperature（Tg）.It was found that the corrosion resistance of amorphous alloys is improved to a significant level when the alloys were heated below *** studies showed that thermally activated relaxation process of created disorder,which occurs during sub-Tg annealing,is responsible for the improvement in the corrosion *** dynamics simulations performed on the Cu-Zr amorphous alloys demonstrated that the relaxation process of the alloys is associated with the formation of energetically stable icosahedra and icosahedron-like *** study highlights the effects of sub-Tg annealing on the improvement in the corrosion resistance of the amorphous alloys from the viewpoint the relaxation process of the short-range orders.

关键词： Amorphous alloys Corrosion Annealing Molecular dynamics Electrochemical performance

Improvements of model-test method for cavitation-induced pressure fluctuation in marine propeller

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Journal of Hydrodynamics 2013年第4期25卷 599-605页

作者： lee Jeung-Hoon HAN jae-Moon PARK Hyung-Gil SEO Jong-Soo Samsung Ship Model Basin (SSMB) Marine Research Institute Samsung Heavy Industries Science Town

Although the prediction of propeller cavitation-induced pressure fluctuation strongly depends on the model-scalemeasure- ment in a cavitation tunnel, there is still a lack of correlation with full-scale data. This paper deals with the enhancement of such a correlation deficiency by improving the conventional model-test technique, two majors of which are in the following. One is to take into account the boundary layer effect of wooden fairing plate at the ceiling of water cavitation tunnel. The other is to avoid the reso- nance frequency range of model-ship via adjusting the revolution speed of model propeller. Through a case study, for which both model and full-scale test data are available, the improved method in this study shows its validness, and furthermore a close correla- tion with full scale measurement.

关键词： cavitation boundary layer resonance

Prediction of grain structure in direct-chill cast Al–Zn–Mg–Cu billets using cellular automaton-finite element method

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Progress in Natural Science:Materials International 2021年第3期31卷 434-441页

作者： Min-Seok Kim Sang-Hwa lee jae-Gil Jung Kwangjun Eah Department of Materials Science and Engineering Gachon University Metallic Materials Division Korea Institute of Materials Science Department of Materials Science and Engineering Yonsei University

A cellular automaton-finite element(CA-FE) model was used to predict the solidification grain structure of permanent mold cast A7086 alloy. In this model, a Gaussian distribution of nucleation sites was adopted, and the Kurz-Giovanola-Trivedi model was extended to a multicomponent Al–Zn–Mg–Cu alloy system to determine the growth kinetics of the dendrite tip. For describing the Gaussian distribution of nucleation sites on the mold surface, an empirical relationship between the initial cooling rate of the melt and the nucleation density was proposed. Under various casting conditions, the calculated grain structures agreed well with the experimental results. Subsequently, the model was applied to the direct-chill(DC) cast billets, and the simulated grain structures reproduced well the experimental results. This confirmed that the current CA-FE model can be used practically and effectively in DC casting processes.

关键词： Cellular automaton-finite element (CA-FE) model Direct-chill casting Al–Zn–Mg–Cu alloy A7068 alloy Grain structure

Impact of uneven distribution of grain characteristics on yield strength and martensitic transformation of as-hot-rolled medium-entropy alloys

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Journal of Materials Science & Technology 2024年第10期177卷 234-245页

作者： Jungwan lee Hyojin Park Sujung Son jae Wung Bae Jin You Kim Sung Kyu Kim jae-il Jang Hyoung Seop Kim Department of Materials Science and Engineering Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Department of Metallurgical Engineering Pukyong National UniversityBusan 48513Republic of Korea Technical Research Laboratories Energy and Shipbuilding Steel Research GroupPOSCOPohangRepublic of Korea Division of Materials Science and Engineering Hanyang UniversitySeoul 04763Republic of Korea Graduate Institute of Ferrous&Eco Materials Technology(GIFT) Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Center for Heterogenic Metal Additive Manufacturing Pohang University of Science and Technology(POSTECH)Pohang 37673Republic of Korea Advanced Institute for Materials Research(WPI-AIMR) Tohoku UniversitySendai 980-8577Japan

As-hot-rolled medium-entropy alloys(MEAs)with unevenly distributed grain sizes of face-centered cubic grains exhibit better yield strength without uniform elongation loss compared to cold-rolled and an-nealed *** operation of dynamic recrystallization(DRX)during several hot rolling passes leads to a wide range of grain sizes from submicrons to tens of micrometers due to the grain growth after nucleation:early recrystallized grains are coarser than recently recrystallized *** only the grain size but internal dislocation density of the recently recrystallized grain is *** the tensile deformation of the hot-rolled MEAs at-196 ℃,dislocation pile-ups in the relatively soft and fine DRX grains enhance yield stress and hetero-deformation-induced strain *** to the enhanced yield stress of the as-hot-rolled MEAs,stress-induced martensitic transformation easily ***,partially DRXed MEAs hot-rolled at 800 ℃ have lower yield stress than fully DRXed ones,hot-rolled at 900 and 1000 ℃.This is attributed to the softening effect of the stress-induced body-centered cubic martensitic transformation in unrecrystallized coarse grains prior to the yielding,which lowers the yield stress of the partially DRXed *** yielding,the martensitic transformation facilitates strain hard-ening and early necking is *** study presents a fresh outlook on the uneven distribution of grain sizes by hot rolling beneficial to mechanical responses of uniform elongation of~45%despite the as-rolled states with an advantage of simplified thermo-mechanical processes.

关键词： Dynamic recrystallization Nucleation and growth Heterogeneity Grain size distribution Deformation-induced martensitic transformation

Efficacy and safety of ecabet sodium on functional dyspepsia:A prospective,double-blinded,randomized,multi-center controlled trial

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World Journal of Gastroenterology 2006年第17期12卷 2756-2761页

作者： Jun Haeng lee jae J Kim Ki-Baik Hahm Dong Ho lee Nayoung Kim Sung Kook Kim Jong jae Park Seok Reyol Choi Jong Hun lee Soo Teik lee Eun Hyun lee Jong Chul Rhee Department of Medicine Sungkyunkwan University School of Medicine SeoulKorea Department of Gastroenterology Ajou University School of Medicine SuwonKorea Department of Internal Medicine Seoul National University Bundang Hospital SeoungnamGyeonggi-doKorea Department of Internal Medicine Kyungpook National University College of Medicine DaeguKorea Department of Internal Medicine Korea University Guro Hospital SeoulKorea Department of Internal Medicine Dong-A University BusanKorea Department of Internal Medicine Chonbuk National University College of Medicine ChonjuKorea Department of Preventive Medicine Graduate School of Public Health Ajou UniversitySuwonKorea

AIM： To compare ecabet sodium and cimetidine in relieving symptoms of functional dyspepsia. METHODS： We performed a multi-center, prospective, randomized, double-blinded controlled trial to compare the clinical efficacy of ecabet sodium and cimetidine in patients with functional dyspepsia. Two-hundred and seventy-two patients with dyspeptic symptoms fulfilling the Rome-II criteria were enrolled from 7 centers. In the study group （115 patients）, 1.5 g ecabet sodium was given twice a day. In the control group （121 patients）, 400 mg cimetidine was given twice a day. Symptoms and parameters of quality of life were analyzed at baseline, 3, 14, and 28 d after initiating the treatment. RESULTS： Two-hundred and thirty-six patients completed the clinical trial. After 4 wk of treatment, the rates of improvement in patients with dyspeptic symptoms were not different between two groups （77.4% in the ecabet group and 79.3% in the cimetidine group, respectively, P 〉 0.05）. Likewise, the rates of symptomatic improvement were not different at 3 d and 14 d. The parameters of quality of life did not change significantly during the study period in both groups. There was no clinically significant adverse event in both groups.

关键词： Functional dyspepsia Ecabet sodium Cimetidine

Improvement in tensile strength of extruded Mg-5Bi alloy through addition of Sn and its underlying strengthening mechanisms

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Journal of Magnesium and Alloys 2022年第11期10卷 3100-3112页

作者： Sang-Cheol Jin jae Won Cha Jeong Hun lee Taekyung lee Sang-Ho Han Sung Hyuk Park School of Materials Science and Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Ulsan Regional Division Korea Institute of Industrial TechnologyUlsan 44413Republic of Korea School of Mechanical Engineering Pusan National UniversityBusan 46241Republic of Korea Department of Materials Analysis Korea Institute of Materials ScienceChangwon 51508Republic of Korea

Through an investigation of the microstructure and mechanical properties of extruded Mg–5Bi–x Sn(BT5x, x = 0, 2, 4, and 6 wt%) alloys,this study demonstrates that the addition of Sn to an Mg–5Bi binary alloy significantly improves the tensile strength of the extruded *** the extruded alloys exhibit a typical basal fiber texture and a partially dynamically recrystallized(DRXed) microstructure consisting of fine DRXed grains and coarse un DRXed grains. As the Sn content increases from 0 wt% to 6 wt%, the average size of the DRXed grains decreases from 4.2 to 2.8 μm owing to the increase in the amount of precipitates via their grain-boundary pinning effect. The extruded B5 and BT52 alloys contain numerous Mg_(3)Bi_(2) precipitates, but their size and number density are smaller and higher, respectively, in the latter *** Mg_(2)Sn precipitates as well as Mg_(3)Bi_(2)precipitates are present in the extruded BT54 and BT56 alloys, and the number density of the Mg_(2)Sn precipitates is higher in the latter alloy because of its higher Sn content. The addition of 2 wt% Sn to the B5 alloy significantly improves the yield strength(YS) and ultimate tensile strength(UTS) of the extruded alloy—by 76 and 57 MPa, respectively. This drastic improvement is the combined outcome of enhanced grain-boundary hardening, precipitation hardening, and solid-solution hardening effects induced by the refined DRXed grains, numerous precipitates, and Sn solute atoms, respectively. The further addition of 2 wt% or 4 wt% Sn to the BT52 alloy leads to moderate increments in the YS and UTS of the extruded alloy. Specifically, each addition of 2 wt% Sn increases the YS and UTS by ~26 and ~20 MPa, respectively, which is attributed mainly to the additional precipitation hardening effect induced by the Mg_(2)Sn precipitates.

关键词： Mg-Bi-Sn alloy Extrusion Precipitation Microstructure Tensile property

Tetradentate Pt(Ⅱ)complex as a singlet exciton sensitizing host for highly efficient green fluorescent organic light-emitting diodes

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Science China Materials 2024年第8期67卷 2618-2627页

作者： Unhyeok Jo Seung Chan Kim Chan Hee Ryu Kang Mun lee jae-Min Kim Jun Yeob lee School of Chemical Engineering Sungkyunkwan University2066Seobu-roJangan-guSuwon-siGyeonggi-do 16419Republic of Korea Department of Chemistry Institute for Molecular Science and Fusion TechnologyKangwon National UniversityChuncheonGangwon 24341Republic of Korea Department of Advanced Materials Engineering Chung-Ang University4726Seodong-daeroDaedeok-myeonAnseong-siGyeonggi-do 17546Republic of Korea SKKU Advanced Institute of Nano Technology Sungkyunkwan University2066Seobu-roJangan-guSuwonGyeonggi 16419Republic of Korea SKKU Institute of Energy Science and Technology Sungkyunkwan University2066Seobu-roJangan-guSuwonGyeonggi 16419Republic of Korea

Efficient green fluorescent organic light-emitting diodes were designed with a phosphorescent metal complex as a singlet exciton sensitizing host(SESH)for achieving high efficiency and low efficiency roll-off through exciton and polaron *** Pt(Ⅱ)complex(Pt-Trz)possessing a tetradentate ligand with a bulky blocking group not only suppresses the severe formation of excimer or dimer itself but also transfers radiative excitons to fluorescent dopant *** SESH assisted fluorescence(SESHF)device with Pt-Trz as the host exhibits the maximum external quantum efficiency of 13.3%and a lower efficiency roll-off compared with exciplex host device which is a general approach for harvesting triplet *** exciton dynamics modeling unravels that the SESHF device effectively utilizes triplet excitons in the host by intersystem crossing and resonance energy transfer from the triplet state of the host to the singlet state of the terminal *** quenching rates of the SESHF device are reduced by 11 times for triplet-triplet annihilation and 1.8 times for tripletpolaron annihilation compared with the exciplex device,which demonstrates that Pt-Trz could be a platform to be used as an efficient host for fluorophores.

关键词： singlet annihilation polaron