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LOW CYCLE FATIgUE BEHAVIOR OF AZ91HP ALLOY IN AS HIgHP RESSURE DIE CASTINg

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Acta Metallurgica Sinica(English Letters) 2000年第4期13卷 961-966页

作者： Liu, Z. Xu, Y.Y. Wang, Z.g. Wang, Y. Liu, Z.Y. Inst of Metal Research Chinese Acad of Sciences Shenyang China

Fully reversed total strain-controlled low-cycle fatigue tests were conducted at room temperature in air to study the fatigue behavior of AZ91HP magnesium alloy in as high pressure die casting and subsequently heat treatment. All the specimens in different heat histories exhibit cyclic strain hardening in different degrees. It is difficult to distinguish the fatigue behavior of the die casting specimens from that of the solution aging specimens. The solution treated specimens show longer fatigue life at high strain amplitude and shorter fatigue life at low strain amplitude than the die casting and solution aging specimens though they have the lowest yield strength with higher strain hardening. Fatigue fracture surfaces for strain amplitude larger than 0.005 show very similar to those found by monotonic tensile tests. The SEM examination reveals that the regions of fatigue crack growth and final fracture can be characterized by quasi-cleavage mechanisms, but some shallow dimples, slip bands and secondary cracks are found on the fracture surface in the fracture crack growth areas.

关键词： Cracks Die casting Fatigue of materials Heat treatment

Repression of Cell Proliferation by miR319-Regulated TCP4

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Molecular Plant 2014年第10期7卷 1533-1544页

作者： Carla Schommer Juan M. Debernardi Edgardo g. Bresso Ramiro E. Rodriguez Javier F. Palatnik IBR (Instituto de Biologia Molecular y Celular de Rosario) CONICET and Facultad de Ciencias Bioquimicas y Farmaceuticas UniversidadNacional de Rosario 2000 Rosario Argentina

Leaf development has been extensively studied on a genetic level. However, little is known about the inter- play between the developmental regulators and the cell cycle machinery--a link that ultimately affects leaf form and size. miR319 is a conserved microRNA that regulates TCP transcription factors involved in multiple developmental pathways, including leaf development and senescence, organ curvature, and hormone biosynthesis and signaling. Here, we analyze the participation of TCP4 in the control of cell proliferation. A small increase in TCP4 activity has an immediate impact on leaf cell number, by significantly reducing cell proliferation. Plants with high TCP4 levels have a strong reduction in the expression of genes known to be active in g2-M phase of the cell cycle. Part of these effects is mediated by induction of miR396, which represses growth-Regulating Factor （gRF） transcription factors. Detailed analysis revealed TCP4 to be a direct regulator of MIR396b. However, we found that TCP4 can control cell proliferation through additional pathways, and we identified a direct connection between TCP4 and ICK1/KRP1, a gene involved in the progression of the cell cycle. Our results show that TCP4 can activate different pathways that repress cell proliferation.

关键词： microRNA miR396 miR319 TCP gRF ICK1 KRP1 proliferation.

Uniformity Structures on L-Fuzzy Spaces

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维普期刊数据库

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模糊系统与数学 2009年第4期23卷 131-143页

作者： K.A.Dib O.A.Tantawy A.E.Shlaan g.A.Kamel Department of Mathematics Faculty of ScienceFayom University Department of Mathematics Faculty of ScienceZagazig University Department of Mathematics Faculty of ScienceFayoum University

We extend the notion of a uniform space in a natural way by defining a uniform spaces in L-fuzzy *** these spaces seem quite similar to ordinary case,we show that the category of this uniform spaces is a good extension of the category of ordinary uniform spaces and the category of L-uniform ***,we introduce the concept of uniform topological spaces in the framework of uniform spaces in L-fuzzy ***,the relation between proximity and uniform spaces in L-fuzzy spaces will be established.

关键词：模糊数学模糊系统模糊集理论

The Pushtashan juvenile suprasubduction zone assemblage of Kurdistan (northeastern Iraq): A Cretaceous (Cenomanian) Neo-Tethys missing link

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geoscience Frontiers 2017年第5期8卷 1073-1087页

作者： Sabah A.Ismail Sarmad A.Ali Allen P.Nutman Vickie C.Bennett Brain g.Jones Department of Applied geology College of Sciences Kirkuk University Kirkuk 36001 Iraq geoQuEST Research Centre School of Earth & Environmental Sciences University of Wollongong Wollongong NSW 2522 Australia Research School of Earth Sciences Australian National University ACT 0200 Australia

The Pushtashan suprasubduction zone assemblage of volcanic rocks, gabbros, norites and peridotites occurs in the Zagros suture zone, Kurdistan region, northeastern Iraq. Volcanic rocks are dominant in the assemblage and consist mainly of basalt and basaltic andesite flows with interlayered red shale and limestone horizons. Earlier lavas tend to be MORB-like, whereas later lavas display island arc tholeiite to boninitic geochemical characteristics. Tholeiitic gabbros intrude the norites and display fractionation trends typical of crystallisation under low-pressure conditions, whereas the norites display calc-alkaline traits, suggesting their source included mantle metasomatised by fluids released from subducted oceanic crust. Enrichment of Rb, Ba, Sr, Th and the presence of negative Nb anomalies indicate generation in a suprasubduction zone setting. Trondhjemite and granodiorite intrusions are present in the volcanic rocks, gabbros and norites. SHRIMP U-Pb dating of magmatic zircons from a granodiorite yields a mean^(206)Pb/^(238)U age of 96.0 ±2.0 Ma(Cenomanian). The initial ε_(Hf) value for the zircons show a narrow range from +12.8 to+15.6, with a weighted mean of + 13.90±0.96. This initial value is within error of model depleted mantle at 96 Ma or slightly below that, in the field of arc rocks with minimal contamination by older continental crust. The compositional bimodality of the Pushtashan suprasubduction sequence suggests seafloor spreading during the initiation of subduction, with a lava stratigraphy from earlyerupted MORB transitioning into calc-alkaline lavas and finally by 96 Ma intrusion of granodioritic and trondhjemitic bodies with juvenile crustal isotopic signatures. The results confirm another Cretaceous arc remnant preserved as an allochthon within the Iraqi segment of the Cenozoic Zagros suture zone. Implications for the closure of Neo-Tethys are discussed.

关键词： Pushtashan suprasubduction assemblage Cretaceous Zircon U-Pb dating Hf isotopes Kurdistan region lraq Neo-Terhys

Inhibition effect of a synthesized N,N′-bis(2-hydroxybenzaldehyde)-1,3-propandiimine on corrosion of mild steel in HCl

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Journal of Central South University 2013年第2期20卷 301-311页

作者： O. ghasemi I. Danaee g.R. Rashed M. RashvandAvei M. H. Maddahy Abadan Faculty of Petroleum Engineering Petroleum University of Technology Abadan 63165-619 Iran Department of Chemistry K. N. Toosi University of Technology Tehran 15875-4416 Iran

The corrosion inhibition of mild steel in 1 mol/L HC1 by N, N＇-bis （2-hydroxybenzaldehyde）- 1, 3-propandiimine （2-HBP） has been investigated by using potentiodynamic polarization, electrochemical impedance spectroscopy （EIS） and chronoamperometry measurements. The experimental results suggest that this compound is an excellent corrosion inhibitor for mild steel and the inhibition efficiency increases with the increase in inhibitor concentration. Polarization curves reveal that this organic compound is a mixed type inhibitor. The effect of temperature on the corrosion behavior of mild steel with the addition of the Schiff base was studied in the temperature range from 25 ℃ to 65℃. The experimentally obtained adsorption isotherms follow the Langmuir equation. Activation and thermodynamic adsorption parameters such as Ea, △H, △S,Kads and Ag,ds were calculated by the corrosion currents at different temperatures and using the adsorption isotherm. The morphology of mild steel surface in the absence and presence of 2-HBP was examined by atomic force microscope （AFM） images.

关键词： corrosion inhibitor Schiffbase adsorption Langmuir equation atomic force microscope

Estimation of scale parameters of logistic distribution by linear functions of sample quantiles

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Journal of Harbin Institute of Technology(New Series) 2001年第4期8卷 380-382页

作者： Patrick g O WEKE 王承官吴从炘 Dept. of Mathematics Harbin Institute of Technology

The large sample estimation of standard deviation of logistic distribution employs the asymptotically best linear unbiased estimators based on sample quantiles. The sample quantiles are established from a pair of single spacing. Finally, a table of the variances and efficiencies of the estimator for 5≤n≤65 is provided and comparison is made with other linear estimators.

关键词： order statistics logistic distribution quantile estimation relative efficiencies.

Field test and probabilistic analysis of irregular steel debris casualty risks from a person-borne improvised explosive device

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Defence Technology（防务技术） 2021年第6期17卷 1852-1863页

作者： Piotr W.Sielicki Mark g.Stewart Tomasz gajewski MichałMalendowski Piotr Peksa Hasan Al-Rifaie Robert Studzinski Wojciech Sumelka Institute of Structural Analysis Faculty of Civil and Transport EngineeringPoznan University of Technology5 Maria Skłodowska-Curie Square60-965PoznanPoland Institute of Building Engineering Faculty of Civil and Transport EngineeringPoznan University of Technology5 Maria Skłodowska-Curie Square60-965PoznanPoland Centre for Infrastructure Performance and Reliability The University of NewcastleUniversity DriveCallaghanNSW2308Australia

Person-borne improvised explosive devices(PBIEDs)are often used in terrorist attacks in Western *** study aims to predict the trajectories of PBIED fragments and the subsequent safety risks for people exposed to this *** explosive field test with a typical PBIED composed of a plastic explosive charge and steel nut enhancements was performed to record initial fragment behaviour,including positions,velocity,and trajectory *** data were used to predict the full trajectory of PBIED fragments using a probabilistic *** the probabilistic analyses a probability of fatality or serious injury was *** on the results presented,many practical conclusions can be drawn,for instance,regarding safe evacuation distances if a person were exposed to a suspected PBIED.

关键词： Flying fragments Human safety Person-borne improvised explosive device experiment Probabilistic analysis

Synthesis,sintering,and thermoelectric properties of the solid solution La_(1–x)Sr_(x)CoO_(3±δ)(0≤x≤1)

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Journal of Advanced Ceramics 2018年第2期7卷 160-168页

作者： M.A.BOUSNINA R.DUJARDIN L.PERRIERE F.gIOVANNELLI g.gUEgAN F.DELORME UniversitéFrancois Rabelais de Tours CNRSINSA CVLGREMAN UMR7347IUT de Blois ICMPE ST Microelectronics

In this work, we synthesized cubic perovskite ceramics of the whole La_(1–x)Sr_xCoO_3(0 ≤ x ≤ 1) solid solution for the first time. Synthesis was carried out by solid state reaction and conventional sintering to reach dense ceramics. For x > 0.8, it was necessary to substitute 3% cobalt by silicon to stabilize the cubic perovskite structure. Electrical conductivity increased with Sr content to reach 3×10~5 S·m^(–1) at 330 K for x = 0.3. However, the optimum electrical properties have been found for x = 0.05 at 330 K with PF_(max) = 3.11×10^(–4)W·m^(–1)·K^(–2). Indeed, the Seebeck coefficient was decreasing when x increased to reach values close to 0 for x ≥ 0.3. Thermal conductivity was low at low temperature(≈ 2.5 W×m^(–1)·K^(–1)) and increased up to 6.5 W·m^(–1)·K^(–1) when temperature increased. As the highest power factor was reached at low temperature as well as the lowest thermal conductivity, La_(1–x)Sr_xCoO_3 compounds with low x values appeared as very promising thermoelectric materials around room temperature, on the contrary to layered cobalt oxides. For high x values, Seebeck coefficient values close to zero made these materials unsuitable for thermoelectric applications.

关键词： perovskite cobalt oxide solid solution electrical conductivity thermoelectric

Contamination,Fractionation and Availability of Metals in Urban Soils in the Vicinity of Former Lead and Zinc Smelters,France

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Pedosphere 2013年第2期23卷 143-159页

作者： C.WATERLOT g.BIDAR A.PELFRNE H.ROUSSEL H.FOURRIER F.DOUAY Université Lille Nord de France groupe ISA Equipe Sols et Environnement Laboratoire Génie Civil et géoEnvironnement (LGCgE) Lille Nord de France (EA 4515) Département des Sites et Sols Pollués Agence de I'Environment et de la Matrise de I'Energie (ADEME)

Soil contamination by metals from anthropogenic activities （e.g., mining and smelting） is a major concern for the environment and human health. Environmental availability of cadmium （Cd）, lead （Pb）, zinc （Zn）, copper （Cu）, and indium （In） in 27 urban soils located around two former Pb and Zn smelters in Northern France were studied by analysing the chemical forms of these metals and evaluating their phytoavailability. These metals were determined using flame or electrothermal absorption atomic spectrometry （FAAS or ETAAS）, depending on their concentration levels. After optimisation of the ETAAS method, characteristic mass of In in water and aqua regia were 9.9 and 18 pg, respectively, showing the high sensitivity of the analytical procedure. Metal partitioning was conducted using a four-step sequential extraction procedure. The results showed that Cd and Zn were mainly in the acid-extractable and reducible forms in the urban soils studied. In contrast, Pb and In were largely in the reducible fraction. However, in some samples, the amount of In extracted in the residual or exchangeable fraction was higher than that in the reducible fraction. Copper was mainly found in the reducible and residual fractions. A pot experiment was conducted in a glasshouse with seven soils （six contaminated and one uncontaminated） and two plant species, ryegrass and lettuce. The results showed transfer of metals from the contaminated soils to the shoots of ryegrass and the edible part of lettuce. The metal bioconcentration factor was in the order of Cd 〉〉 Cu 〉 In 〉 Zn 〉〉 Pb for lettuce leaves, whereas for ryegrass shoots, three orders were found, Cd 〉 Zn 〉 Cu 〉〉 In 〉 Pb, Cd 〉〉 In 〉 Zn 〉 Cu 〉〉Pb, and Zn 〉 Cd 〉 Cu 〉 In 〉〉 Pb, depending on the physico-chemical properties of the soils, such as pH, cation exchange capacity, carbonates, and organic matter. It was established that the metal toxicity was related to the contamination levels and the physico-chemical properties, including pH, organi

关键词： bioconcentration factor environmental availability metal toxicity sequential extraction soil physico-chemical property