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Precipitate Behavior in Fe–20Cr–30Ni–2Nb Austenitic Heat-Resistant Steel

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Acta Metallurgica Sinica(English Letters) 2015年第4期28卷 424-429页

作者： Hiroki Ishikawa Chi Zhang sheng-Wei chen Zhi-Gang Yang School of Materials Science and Engineering Tsinghua University Department of Chemistry and Materials Science Tokyo Institute of Technology

In this study, the precipitation behavior of a new austenitic heat-resistant steel （Fe-20Cr-30Ni-2Nb, in at%） was investigated. The effects of alloying addition of boron （B） and lanthanum （La） on the microstructure of the austenitic steel were scrutinized using SEM, EPMA, TEM, and XRD. The results showed that the addition of B enhanced the precipitation of bar-type Laves phase. A small precipitate with high La concentration was observed at the grain boundary in the alloy without aging; similar precipitates without La also presented in region adjacent to the La single phase. This result indicates that La can exist independently and does not contribute to the formation of new compounds. However, in both B- and La-modified alloy, B appeared in the precipitate free zone. In the alloy containing both B and La, only Fe2Nb Laves- phase precipitates, as indicated by the XRD result.

关键词： Precipitation free zone Grain boundary Phase transformation Microstructure Fe-20Cr-30Ni-2Nb austenitic heat-resistant steel

PM_(2.5) in China:Measurements,sources,visibility and health effects,and mitigation

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Particuology 2014年第2期12卷 1-26页

作者： David Y.H.Pui sheng-Chieh chen Zhili Zuo Department of Mechanical Engineering College of Science and EngineeringUniversity of Minnesota

Concern over the health effects of fine particles in the ambient environment led the U.S. Environmental Protection Agency to develop the first standard for PM2.5 （particulate matter less than 2.5 μm） in 1997. The Particle Technology Laboratory at the University of Minnesota has helped to establish the PM2.5 standard by developing many instruments and samplers to perform atmospheric measurements. In this paper, we review various aspects of PM2.5, including its measurement, source apportionment, visibility and health effects, and mitigation. We focus on PM2.s studies in China and where appropriate, compare them with those obtained in the U.S. Based on accurate PM2.5 sampling, chemical analysis, and source apportionment models, the major PM2.5 sources in China have been identified to be coal combustion, motor vehicle emissions, and industrial sources. Atmospheric visibility has been found to correlate well with PM2.s concentration. Sulfate, ammonium, and nitrate carried by PM2.s, commonly found in coal burning and vehicle emissions, are the dominant contributors to regional haze in China. Short-term exposure to PM2.s is strongly associated with the increased risk of morbidity and mortality from cardiovascular and respiratory diseases in China. The strategy for PMzs mitigation must be based on reducing the pollutants from the two primary sources of coal-fired power plants and vehicle emissions. Although conventional Particulate Emission Control Devices （PECD） such as electrostatic precipitators in Chinese coal-fired power plants are generally effective for large particles, most of them may not have high collection efficiency of PM2.5. Baghouse filtration is gradually incorporated into the PECD to increase the PM2.5 collection efficiency. By adopting stringent vehicle emissions standard such as Euro 5 and 6, the emissions from vehicles can be gradually reduced over the years. An integrative approach, from collaboration among academia, government, and industries, can effe

关键词： PM2.5 in ChinaAtmospheric particle size distributionPM2.5 samplingChemical composition of PM2.sSource apportionment modelsPM2.5 health impactPM2.s mitigationCoal-fired power plantParticle emission control devices (PECD)Baghouse filtrationIntegrative approach

Degradation of extracellular genomic, plasmid DNA and specific antibiotic resistance genes by chlorination

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Frontiers of Environmental Science & Engineering 2019年第3期13卷 115-126页

作者： Menglu Zhang sheng chen Xin Yu Peter Vikesland Amy Pruden Key Laboratory of Urban Environment and Health Institute of Urban Environment Chinese Academy of Sciences Xiamen 361021 China University of Chinese Academy of Science Beijing 100049 China Department of Civil and Environmental Engineering Virginia Tech Blacksburg VA 24060 USA

There is a need to improve understanding of the effect of chlorine disinfection on antibiotic resistance genes (ARGs) in order to advance relevant drinking water, wastewater, and reuse treatments. However, few studies have explicitly assessed the physical effects on the DNA. Here we examined the effects of free chlorine (1-20 mg CI2/L) on extracellular genomic, plasmid DNA and select ARGs. Chlorination was found to decrease the fluorometric signal of extracellular genomic and plasmid DNA (ranging from 0.005 to 0.05 μg/mL) by 70%, relative to a no-chlorine control. Resulting DNA was further subject to a fragment analysis using a Bioanalyzer, indicating that chlorination resulted in fragmentation. Moreover, chlorine also effectively deactivated both chromosomal- and plasmidborne ARGs, mecK and tetA., respectively. For concentrations >2 mg CI2//L× 30 min, chlorine efficiently reduced the qPCR signal when the initial concentration of ARGs was 10^5 copies/μL or less. Notably, genomic DNA and mecA gene signals were more readily reduced by chlorine than the plasmid-bome tetK gene (by ~2 fold). Based on the results of qPCR with short (~200 bps) and long amplicons (-1200 bps), chlorination could destroy the integrity of ARGs, which likely reduces the possibility of natural transformation. Overall, our findings strongly illustrate that chlorination could be an effective method for inactivating extracellular chromosomal- and plasmid-bome DNA and ARGs.

关键词： Antibiotic resistance Antibiotic resistance genes (ARGs) Extracellular DNA/ARGs Chlorination

Recent studies on potential accident-tolerant fuel-cladding systems in light water reactors

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Nuclear Science and Techniques 2020年第3期31卷 94-123页

作者： sheng-Li chen Xiu-Jie He Cen-Xi Yuan Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China Universite Grenoble Alpes I-MEP238402 Saint Martin d’HeresFrance

Accident-tolerant fuel(ATF)has attracted considerable research attention since the 2011 Fukushima nuclear *** improve the accident tolerance of the fuel-cladding systems in the current light-water reactors,it is proposed to develop and deploy(1)an enhanced Zrbased alloy or coated zircaloy for the fuel cladding,(2)alternative cladding materials with better accident tolerance,and(3)alternative fuels with enhanced accident tolerance and/or a higher U *** review presents the features of the current UO2-zircaloy *** techniques and characters to develop coating materials and enhanced Zr-based alloys are *** features of several selected alternative fuels and cladding materials are reviewed and *** neutronic evaluations of alternative fuel-cladding systems are *** is expected that one or more types of ATF-cladding systems discussed in the present review will be implemented in commercial reactors.

关键词： Accident-tolerant fuel Accident-tolerant cladding Light-water reactor Neutronic evaluation

Synthesis and Fungicidal Activities of 2-Alkylthio-5-(3,4,5-tribenzyloxyphenyl)-1,3,4-oxadiazoles

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Chinese Chemical Letters 2006年第11期17卷 1427-1430页

作者： De Qing LONG De Jiang LI Wei Quan CAI sheng sheng chen Department of Chemistry Yunyang Teachers College Hubei 442700 College of Chemical Engineering Wuhan University of Technology Wuhan 430070

Abstract： Ten novel 2-alkylthio-5-（3, 4, 5-tribenzyloxyphenyl）-1, 3, 4-oxadiazole derivatives （5a-j） were synthesized from methyl 3, 4, 5-trihydroxybenzoate by ethedfication, hydrazidation, cyclization and thioetherification reactions. The structures of 5a-j were confirmed by 1HNMR, MS spectra and elemental analysis. The results indicated that most of the compounds 5 exhibited good fungicidal activities. The activity of 5h is higher than 90% against Fusarium oxysporum and Botrytis cinereapers in 50 mg/L.

关键词： 1,3,4-Oxadiazole derivatives synthesis fungicidal activity.

A cross-layer approach to enable multipacket transmission in MIMO-SDMA based WLAN

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第2期10卷 271-278页

作者： sheng-bo chen Wei chen Wei-lan HUANG Li-jun ZHAI Xu-ming LIU Department of Electronic Engineering. Tsinghua University Beijing 100084 China Nokia Research Center Beijing 100176 China

We propose a medium access control(MAC) protocol for uplink transmissions in wireless local area networks(WLANs),where both stations and access points(APs) are equipped with multiple antennas. The protocol solves some common problems in utilizing multiple input multiple output(MIMO) under the 802.11 protocol,e.g.,how to deploy preamble(training sequence) used for channel estimation and how to enable simultaneous data transmissions,and facilitates two simultaneous uplink data transmissions via a cross-layer approach. Furthermore,we develop a 3D discrete-time Markov model to analyze the per-formance of the proposed WLAN scheme. The analytical results are verified by simulation,and numerical results show that the system throughput can be significantly improved by our proposed scheme as compared with conventional schemes.

关键词： Multiple input multiple output (MIMO) Medium access control (MAC) Cross-layer design

Patterns of plant sexual systems in subtropical evergreen broad-leaved forests in Ailao Mountains, SW China

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Journal of Plant Ecology 2008年第3期1卷 179-185页

作者： Xin-sheng chen Qing-JunLi Xishuangbanna Tropical Botanical Garden Chinese Academy of SciencesMengla CountyYunnan 666303China Graduate University of Chinese Academy of Sciences Beijing 100039China

Aims Sexual systems influence many components of the ecology and evolution of plant populations and have rarely been documented in subtropical evergreen broad-leaved forests(SEBLF).Here we report frequency distribution and ecological correlates of plant sexual systems in SEBLF at Ailao Mountains,and compare our results with that of tropical and cool temperate *** We examine the sexual systems of 703 species of woody angiosperms belonging to 103 families and 296 genera based on a comprehensive survey of SEBLF at Ailao Mountains Natural *** of plant sexual systems and ecological traits were mainly based on published literatures and specimens as well as our field *** associations between plant sexual system and ecological traits were assessed with chi-square *** findings Among these species,60.2%were hermaphroditic,15.8%were monoecious and 24.0%were *** percentage of dioecious sexual system among tree species(22.2%)in SEBLF was comparable to those of tropical tree floras,but much higher than those of temperate forests at North *** percentage of monoecious sexual system among tree species(30.1%)in SEBLF was higher than that of tropical tree floras,but much lower than those of temperate forests at North *** was significantly associated with the tree growth form and was relatively common in temperate *** was significantly associated with fleshy fruits and monoecy was significantly associated with dry fruit type in *** high percentage of diclinous sexual systems(monoecy and dioecy)in SEBLF may be associated with the origin of the flora and the prevalence of relatively small inconspicuous flowers of the forests in the Oriental Region.

关键词： reproductive trait fruit type dioecy temperate forest

Electric Field-driven Acid-base Transformation： Proton Transfer from Acid（HBr/HF） to Base（NH3/H2O）

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Chemical Research in Chinese Universities 2015年第3期31卷 418-426页

作者： LIANG Hailong CHAI Baojie chen Guanghui chen Wei chen sheng XIAO Hailan LIN Shujuan Department of Chemistry Shantou University Shantou 515063 P.R.China School of Technology Mudanjiang Normal University Mudanjiang 157012 P.R.China

The proton-transfer between ammonia/water and HF/HBr without and with the stimulus of external electric fields（Eext） was investigated with the ab initio calculations. When external electric field is applied, the proton transfer occurs, resulting in ion-paired HaN＋X- and H30＋X-（X--Br and F） from hydrogen-bonded complexes in view of the great changes of geometrical structures, dipole moments, frontier molecular orbitals and potential energy surfaces in the critical external electric fields（Ec） of 1.131 × 107 V/cm for H3N-HBr, 1.378× 108 V/cm for H3N-HF, 9.358×107 V/cm for H2O-HBr and 2.304×108 V/cm for H2O-HF, respectively. Furthermore, one or three excess electrons can trigger the proton transfer from H3N-HBr and H3N-HF to HaN＋Br- and H4N＋F-, while two and four excess electrons can induce the proton transfer from H2O-HBr and H2O-HF to H3O＋Br- and H30＋F-, respectively. Compared with that of the analogous NH3/H2O-HC1 systems, the strength of Ec of proton transfer increases from HBr to HCL and HF for either H3N-HX or H2O-HX series, which is understandable by the fact that the acidity sequence is HBr〉HCI〉HF. And the larger of acidity of conjugated acid, the smaller of needed Ec. On the other hand, the Ec for the systems of NH3 with a stronger basicity is generally smaller than that of H2O systems for the same con- jugated acid.

关键词： Electric field Proton transfer H3N-HX and H2O-HX(X=Br and F) systems

Kindlin-2 inhibits Nlrp3 inflammasome activation in nucleus pulposus to maintain homeostasis of the intervertebral disc

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Bone Research 2022年第1期10卷 165-177页

作者： sheng chen Xiaohao Wu Yumei Lai Di chen Xiaochun Bai sheng Liu Yongchao Wu Mingjue chen Yuxiao Lai Huiling Cao Zengwu Shao Guozhi Xiao Department of Orthopaedics Union HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhan 430022China Department of Biochemistry School of MedicineSouthern University of Science and TechnologyGuangdong Provincial Key Laboratory of Cell Microenvironment and Disease ResearchShenzhen Key Laboratory of Cell MicroenvironmentShenzhen 518055China Department of Orthopedic Surgery Rush University Medical CenterChicagoIL 60612USA Research Center for Human Tissues and Organs Degeneration Shenzhen Institutes of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China Department of Cell Biology School of Basic Medical SciencesSouthern Medical UniversityGuangzhou 510515China Centre for Translational Medicine Research and Development Institute of Biomedical and Health EngineeringShenzhen Institute of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China

Intervertebral disc(IVD) degeneration(IVDD) is the main cause of low back pain with major social and economic burdens;however, its underlying molecular mechanisms remain poorly defined. Here we show that the focal adhesion protein Kindlin-2 is highly expressed in the nucleus pulposus(NP), but not in the anulus fibrosus and the cartilaginous endplates, in the IVD tissues. Expression of Kindlin-2 is drastically decreased in NP cells in aged mice and severe IVDD patients. Inducible deletion of Kindlin-2 in NP cells in adult mice causes spontaneous and striking IVDD-like phenotypes in lumbar IVDs and largely accelerates progression of coccygeal IVDD in the presence of abnormal mechanical stress. Kindlin-2 loss activates Nlrp3 inflammasome and stimulates expression of IL-1β in NP cells, which in turn downregulates Kindlin-2. This vicious cycle promotes extracellular matrix(ECM) catabolism and NP cell apoptosis. Furthermore, abnormal mechanical stress reduces expression of Kindlin-2, which exacerbates Nlrp3 inflammasome activation, cell apoptosis, and ECM catabolism in NP cells caused by Kindlin-2 deficiency. In vivo blocking Nlrp3 inflammasome activation prevents IVDD progression induced by Kindlin-2 loss and abnormal mechanical stress. Of translational significance, adeno-associated virus-mediated overexpression of Kindlin-2 inhibits ECM catabolism and cell apoptosis in primary human NP cells in vitro and alleviates coccygeal IVDD progression caused by mechanical stress in rat. Collectively, we establish critical roles of Kindlin-2 in inhibiting Nlrp3 inflammasome activation and maintaining integrity of the IVD homeostasis and define a novel target for the prevention and treatment of IVDD.

关键词： Kindlin homeostasis prevention