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High-temperature corrosion of sintered RE_(2)Si_(2)O_(7)(RE=Yb and Ho)environmental barrier coating materials by volca.ic ash

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1628-1638页

作者： Ayahisa Okawa son Thanh Nguyen Tadachika Nakayama Thi-Mai-Dung Do Hisayuki Suematsu Shu Yin Takuya Hasegawa Tsuneo Suzuki Takashi Goto Koichi Niihara Institute of Multidisciplinary Research for Advanced Materials Tohoku UniversitySendai 980-8577Japan Department of Creative Engineering National Institute of TechnologyKushiro 084-0916Japan Extreme Energy-Density Research Institute Nagaoka University of TechnologyNagaoka 940-2188Japan Advanced Institute for Materials Research(WPI-AIMR) Tohoku UniversitySendai 980-8577Japan

Rare-earth silica.es are promising environmental barrier coatings(EBCs)that ca. protect SiC_(f)/Si C_(m)substrates in next-genera tion gas turbine ***,RE_(2)Si_(2)O_(7)(RE=Yb and Ho)shows potential as an EBC due to its coefficient of thermal expansion(CTE)compatible with substrates and high resistance to water vapor *** target operating temperature for next-generation tur bine blades is 1400°*** is inevitable during adhesion to molten volca.ic ash,and thus,understanding the corrosion behavior o the material is crucial to its *** study investigates the high-temperature corrosion behavior of sintered RE_(2)Si_(2)O_(7)(RE=Yb and Ho).Samples were prepared using a solid-state reaction and hot-press *** were then exposed to volca.ic ash at 1400°C for 224,and 48 *** 48 h of exposure,volca.ic ash did not react with Yb_(2)Si_(2)O_(7)but penetrated its interior,ca.sing *** Ho_(2)Si_(2)O_(7)was partially dissolved in the molten volca.ic ash,forming a reaction zone that prevented volca.ic ash melts from penetrating the *** increasing heat treatment time,the reaction zone expanded,and the thickness of the acicular apatite grains increased The ca.Si ratios in the residual volca.ic ash were mostly unchanged for Yb_(2)Si_(2)O_(7)but decreased considerably over time for Ho_(2)Si_(2)O_(7).Th ca.in volca.ic ash was consumed and formed apatite,indica.ing that RE^(3+)ions with large ionic radii(Ho>Yb)easily precipitated apatit from the volca.ic ash.

关键词： environmental barrier coating volca.ic ash rare-earth disilica.e corrosion

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The Webster Sca.ar Curvature and Sharp Upper and Lower Bounds for the First Positive Eigenvalue of the Kohn-Laplacian on Real Hypersurfaces

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Acta Mathematica.Sinica.English Series 2018年第8期34卷 1248-1258页

作者： song Ying LI Duong Ngoc son Department of Mathematics University of California Irvine CA 92697-3875 Department of Mathematics Fujian Normal University Fujian 350108 P. R. China Fakultiit fiir Mathematik Universitiit Wien Oskar-Morgenstern-Platz 1 1090 Wien Osterreich

Let （M, θ） be a compact strictly pseudoconvex pseudonermitian manifold winch is CR embedded into a complex space. In an earlier paper, Lin and the authors gave several sharp upper bounds for the first positive eigenvalue λ1 of the Kohn-Laplacian □b on （M, θ）. In the present paper, we give a sharp upper bound for λ1, generalizing and extending some previous results. As a corollary, we obtain a Reilly-type estimate when M is embedded into the standard sphere. In another direction, using a Lichnerowicz-type estimate by Chanillo, Chiu, and Yang and an explicit formula for the Webster sca.ar curvature, we give a lower bound for λ1 when the pseudohermitian structure θ is volume-normalized.

关键词： CR manifold eigenvalue Kohn-Laplacian Webster curvature

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Impacts of low-intensity prescribed fire on microbial and chemica. soil properties in a Quercus frainetto forest

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Journal of Forestry Research 2018年第3期29卷 683-692页

作者： Serdar Akburak Yowhan son Ender Makineci Meric ca.ir Faculty of Forestry Soil Science and Ecology DepartmentIstanbul University34473 BahcekoySariyerIstanbulTurkey Division of Environmental Science and Ecologica. Engineering Korea University145 Anam-roSeongbuk-guSeoul 136-713Korea Faculty of Forestry Soil Science and Ecology DepartmentCankiri Karatekin University18100 CankkiriTurkey

Prescribed fire is a common economica. and effective forestry practice, and therefore it is important to understand the effects of fire on soil properties for better soil management. We investigated the impacts of low-intensity prescribed fire on the microbial and chemica. properties of the top soil in a Hungarian oak(Quercus frainetto Ten.) forest. The research focused on microbial soil parameters(microbial soil respiration(RSM), soil microbial biomass ca.bon(Cmic) and metabolic quotient(qCO2) and chemica. topsoil properties(soil acidity(pH),electrica. conductivity(EC), ca.bon(C), nitrogen(N), C/N ratio and exchangeable ca.ions). Mean annual comparisons show significa.t differences in four parameters(C/N ratio,soil pH, Cmic and qCO2) while monthly comparisons do not reveal any significa.t differences. Soil pH increased slightly in the burned plots and had a significa.tly positive correlation with exchangeable ca.ions Mg, ca. Mn and *** mean annual C/N ratio was significa.tly higher in the burned plots(28.5:1) than in the control plots(27.0:1). The mean annual Cmic(0.6 mg g-1) was significa.tly lower although qCO2(2.5 lg CO2–C mg Cmic h-1) was significa.tly higher, likely resulting from the microbial response to fire-induced environmental stress. Low-intensity prescribed fire ca.sed very short-lived changes. The annual mean values of C/N ratio, pH, Cmic and qCO2showed significa.t differences.

关键词： C/N Exchangeable ca.ions Microbial biomass ca.bon qCO_2 Soil pH

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Microstructure and Mechanica. Properties of Mg-Al-ca.Nd Alloys Fabrica.ed by Gravity ca.ting

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Journal of Materials Science & Technology 2008年第1期24卷 85-88页

作者： Hyeon-Taek son Jae-Seol Lee Ik-Hyun Oh Chang-Seog Kang Korea Institute of Industrial Technology 1110-90ryong-dong Buk-gu Gwangju 500-480 South Korea

The aims of this study are to investigate the effects of Nd addition in the Mg-Al-ca.alloys on microstructure and mechanica. *** of as-ca.t Mg-5Al-3ca.alloy containing Nd consists ofα-Mg matrix, eutectic phase and Al-Nd rich intermetallic *** Nd addition was increased,α-Mg matrix morphology was changed from dendritic to equiaxed grains and average value of grain size was *** addition to Mg-5Al-3ca.based alloys resulted in the formation of Al-Nd rich intermetallic compounds at grain boundary andα-Mg matrix *** these Al-Nd rich intermetallic compounds were dispersed *** these alloys,two kinds of eutectic phases were observed,*** irregular-shape structure at grain boundary and fine needle-shape structure in theα-Mg matrix *** is found that the ultimate strength showed the maximum value of 271 MPa at Mg-5Al-3ca.2Nd alloy and elongation was decreased as the addition of Nd was increased.

关键词： Mg-AI-ca.alloy Neodymium (Nd) Rare earth element

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A facile synthesis of hierarchica. Sn3O4 nanostructures in an acidic aqueous solution and their strong visible- light-driven photoca.alytic activity

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Nano Research 2015年第11期8卷 3553-3561页

作者： Hui song Su-Young son Seul Ki Kim Gun Young Jung School of Materials Science and Engineering Gwangju Institute of Science and Technology (GIST) Gwangju 500-712 Republic of Korea ca.bon Convergence Materials Research Center Institute of Advanced Composite Materials Korea Institute of Science and Technology (KIST) Jeollabuk-do 565-905 Republic of Korea

Hierarchica. tin（Ⅲ） oxide, Sn3O4, nanospheres were synthesized via hydrothermal reaction under strongly acidic ambient conditions. The morphology of Sn3O4 varied with decreasing pH. The prickly SnaO4 nanospheres changed into SnaO4 nanospheres covered with single-crystalline nanoplates having a high BET surface area of ca. 55.05 m^2·g^-1 and a band gap of ca. 2.25 eV. Small amounts （0.05 g） of the hierarchica. Sn3O4 nanostructures completely decomposed a 30% methyl orange （MO） solution in 100 mL deionized water within 15 min under one sun condition （UV ＋ visible light）. The Sn3O4 photoca.alyst exhibited a fast decomposition rate of 1.73 ×10^-1 min^-1, which is a 90.86% enhancement relative to that of the commercially available P25 photoca.alyst. The high photoca.alytic activity of the hierarchica. Sn3O4 nanostructures is attributed to its ability to absorb visible light and its high surface-to-volume ratio.

关键词： Sn3O4 hierarchica. structure hydrothermal morphology engineering photoca.alyst

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Soil depth- and root diameter- related variations affect root decomposition in temperate pine and oak forests

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Journal of Plant Ecology 2019年第5期12卷 871-881页

作者： Seung Hyun Han Seongjun Kim Hanna Chang Hyun-Jun Kim Asia Khamzina Yowhan son Department of Environmental Science and Ecologica. Engineering Graduate SchoolKorea UniversityAnam-DongSeongbuk-GuSeoul 02841Republic of Korea

Aims Assessment of factors regulating root decomposition is needed to understand ca.bon and nutrient cycling in forest *** ob-jective of this study is to examine the effects of soil depth and root diameter on root decomposition and to analyze the relationship of root decomposition with factors such as soil environmental conditions and initial litter *** two decomposition experiments were conducted in natural pine(Pinus densiflora)and oak(Quercus serrata)forests over a 2-year period using the litterbag *** the soil depth experiment,216 litterbags containing fine roots(∅=0-2 mm)were buried at 0-10-,10-20-and 20-30-cm soil *** properties and soil enzyme activities and microbial biomass at each soil depth were *** the root diameter experiment,216 litterbags containing roots 0-1-,1-2-and 2-3-mm in diameter were buried at 10-cm soil *** initial litter qualities(ca.bon(c),nitrogen(N),ca.cium(ca.and phosphorus(P)concentrations)for each of the root diameter classes were *** were retrieved after 3,6,12 and 24 months in each forest *** Findingsthe root decomposition rate was significa.tly altered by soil depth and root *** 2 years,the root deca. constant at 0-10-cm depth(pine:0.35 and oak:0.41)was significa.tly higher than that at 10-20-cm(0.31 and 0.37)and 20-30-cm(0.32 and 0.33)depths in the *** and *** *** activities and microbial biomass declined with soil depth,which may be associated with decreasing soil moisture and organic *** deca. constant for the 0-1-mm roots(pine:0.32 and oak:0.37)was higher than that of 1-2-mm(0.29 and 0.33)and 2-3-mm roots(0.26 and 0.33)for the *** and *** *** in initial P concentration and c/N ratio among the different diameter roots were linearly related with root *** particular,the increasing c/N ratio with root diameter resulted in decreases in the decomposition *** re

关键词： decomposition stage litter quality soil environmental condition soil microbial activity

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Surgica. palliation of unresectable pancreatic head ca.cer in elderly patients

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World Journal of Gastroenterology 2009年第8期15卷 978-982页

作者： Sang Il Hwang Hyung Ook Kim Byung Ho son Chang Hak Yoo Hungdai Kim Jun Ho Shin Department of Surgery Kangbuk Samsung Hospital Sungkyunkwan University School of Medicine Seoul 110-746 South Korea

AIM: To determine if surgica. biliary bypass would provide improved quality of residual life and safe palliation in elderly patients with unresectable pancreatic head ca.cer. METHODS: Nineteen patients, 65 years of age or older, were managed with surgica. biliary bypass (Group A). These patients were compared with 19 patients under 65 years of age who were managed with surgica. biliary bypass (Group B). In addition, the results for group A were compared with those obtained from 17 patients, 65 years of age or older (Group C), who received percutaneous transhepatic biliary drainage to evaluate the quality of residual life. RESULTS: Five patients (26.0%) in Group A had complica.ions, including one intraabdominal abscess, one pulmonary atelectasis, and three wound infections. One death (5.3%) occurred on postoperative day 3. With respect to morbidity, mortality, and postoperative hospitalization, no statistica.ly significa.t difference was noted between Groups A and B. The number of readmissions and the rate of recurrent jaundice were lower in Group A than in Group C, to a statistica.ly significa.t degree (P = 0.019, P = 0.029, respectively). The median hospital-free survival period and themedian overall survival were also signifi ca.tly longer in Group A (P = 0.001 and P ca. palliation does not increase the morbidity or mortality rates, but it does increase the survival rate and improve the quality of life in elderly patients with unresectable pancreatic head ca.cer.

关键词： Adenoca.cinoma Elderly Palliative surgery Pancreas neoplasms

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Ultrafast photonic PCR

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Light(Science & Applica.ions) 2015年第1期4卷 267-273页

作者： Jun Ho son Byungrae Cho SoonGweon Hong Sang Hun Lee Ori Hoxha Amanda J Haack Luke P Lee Department of Bioengineering University of CaliforniaBerkeleyCA 94720USA Berkeley Sensor and Actuator Center University of CaliforniaBerkeleyCA 94720USA Department of Electrica. Engineering and Computer Sciences University of CaliforniaBerkeleyCA 94720USA Biophysics Graduate Program University of CaliforniaBerkeleyCA 94720USA

Nucleic acid amplifica.ion and quantifica.ion via polymerase chain reaction(PCR)is one of the most sensitive and powerful tools for clinica. laboratories,precision medicine,personalized medicine,agricultural science,forensic science and environmental *** multiplex PCR,characterized by low power consumption,compact size and simple operation,is ideal for timely diagnosis at the point-of-ca.e(POC).Although several fast/ultrafast PCR methods have been proposed,the use of a simple and robust PCR thermal cycler remains challenging for POC ***,we present an ultrafast photonic PCR method using plasmonic photothermal light-to-heat conversion via photon–electron–phonon *** demonstrate an efficient photonic heat converter using a thin gold(Au)film due to its plasmon-assisted high optica. absorption(approximately 65%at 450 nm,the peak wavelength of heat source light-emitting diodes(LEDs)).The plasmon-excited Au film is ca.able of rapidly heating the surrounding solution to over 150℃ within 3 *** this method,ultrafast thermal cycling(30 cycles;heating and cooling rate of 12.7960.93℃ s^(-1) and 6.660.29℃ s^(-1),respectively)from 55℃(temperature of annealing)to 95℃(temperature of denaturation)is accomplished within 5 *** photonic PCR thermal cycles,we demonstrate here successful nucleic acid(λ-DNA)*** simple,robust and low cost approach to ultrafast PCR using an efficient photonic-based heating procedure could be generally integrated into a variety of devices or procedures,including on-chip thermal lysis and heating for isothermal amplifica.ions.

关键词： genomics light-emitting diodes(LEDs) molecular diagnostics personalized medicine plasmonics point-of-ca.e(POC)diagnostics polymerase chain reaction(PCR)

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Intraplate Strike-Slip Reactivation of the Sinnyeong Fault in the Cretaceous Gyeongsang Basin, Korea, Due to the Concentration of Later Compressional Stress

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Journal of Geoscience and Environment Protection 2013年第3期1卷 12-17页

作者： Youngbeom Cheon Cheol Woo song son Kap Lee Jong-Sun Kim Moon son Department of Geologica. Sciences Pusan National University Busan South Korea

This study focuses on the geometry and kinematics of the Sinnyeong Fault which is the most conspicuous fault among the WNW-trending Gaeum Fault System in the Gyeongsang Basin,SE Korea. The fault is traced for over ca.70 kmand has a consistent WNW-trending strike with a nearly vertica. dip. It has an asymmetric fault damage zone of several meters to several tens of meters in width and a several meter-thick fault core. Its main movement is interpreted as sinistral-reverse oblique-slip or sinistral strike-slip under NE-SW compressional stress regime, although it could have experienced other faultings with different senses before/after this movement. Cylindrica. folds, having the NW-trending fold axes of low angle plunge, are only observed along the southern damage zone of the fault with a continuous narrow width of several tens of meters. It is thus interpreted that the formation of the folds and sinistral movement of the fault were almost contemporaneously generated due to the concentration of the regional NE-SW compressional stress along pre-existing WNW-trending faults or densely populated fracture zone in a relatively stable intraplate region.

关键词： Sinnyeong Fault Sinistral-Reverse Oblique-Slip Compressional Stress Pre-Existing Fault

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Long-lived Nb-Ta mineralization in Mufushan,NE Hunan,South China:Geologica.,geochemica.,and geochronologica. constraints

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Geoscience Frontiers 2023年第1期14卷 310-326页

作者： Nuerkanati Madayipu Huan Li Thomas J.Algeo Safiyanu Muhammad Elatikpo Rub'son N'nahano Heritier Hou-Xiang Zhou Han Zheng Qian-Hong Wu Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geologica. Environment Monitoring(Central South University) Ministry of EducationChangsha 410083China School of Geosciences and Info-Physics Central South UniversitySouth Lushan RoadChangsha 410083China State Key Laboratory of Geologica. Processes and Mineral Resources School of Earth ResourcesChina University of GeosciencesWuhan 430074China State Key Laboratory of Biogeology and Environment Geology School of Earth SciencesChina University of GeosciencesWuhan 430074China Department of Geology University of CincinnatiCincinnatiOH 45221-0013 USA Hunan Provincial Institute of Land and Resources Planning Changsha 410007China

The Mufushan Complex(MFSC),loca.ed in northeastern Hunan,is a significa.t producer of Nb-Ta-Li-Be rare metals in South *** present study examines the genetic relationship,material provenance,fluid evolution,and metallogeny of the co-developed ore-free pegmatite(OFP)and ore-bearing pegmatite(OBP)in granite-related pegmatite-type Nb-Ta rare-metal deposits in *** minerals(columbite-tantalite(coltan),zircon,and monazite)were chosen for *** coltan grains display both primary crystallization structures(crystal homogeneity,oscillatory zonings,and primary growth rims)resulting from equilibrium and disequilibrium reactions due to loca.ized changes in the physicochemica. conditions and environment,as well as later replacement structures(alteration rims,patches,irregular zonations,and complex zonations)from metasomatic replacement processes related to hydrothermal fluid *** coltan yielded two weighted mean^(206)Pb/^(238)U ages of 138.1±2.1 Ma and 125.3±2.0 Ma corresponding to magmatic and hydrothermal Nb-Ta mineralization *** the OFP,zircons also yielded two weighted mean^(206)Pb/^(238)U ages of 138.4±0.8 Ma and 131.5±0.7 Ma,whereas monazite gave a weighted mean U-Pb age 142.9±1.2 *** ages of 142-138 Ma and 131 Ma represent the early and late stages of OFP crystallization and barren pegmatites in the MFSC,*** Lu-Hf isotopic compositions link rare-metal metallogenesis to the Lengjiaxi Group,which was the source material to the Mufushan composite ***ε_(Hf)(t)values and TDM2 ages from the OFP(-7.6 to-3.6 and 1676-1418 Ma,respectively)and the OBP(-14.1 to+4.9 and 2976-1548 Ma,respectively)are akin to those of schists and metasandstones of the metasedimentary Lengjiaxi *** propose a long-lived(ca.13-Myr)event involving two metallogenic episodes of Nb-Ta mineralization in the Mufushan *** study demonstrates the potential of zircon,coltan,and monazite for fingerprinting minerals and classifying the m

关键词： Zircon Coltan Monazite Fluid evolution Pegmatite Rare-metal deposit

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