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Simultaneous refinement of α-Mg grains and β-Mg_(17)Al_(12) in Mg-Al based alloys via heterogeneous nucleation on Al_(8)Mn_(4)Sm 被引量:1
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作者 Jun-Chen Chen Mei-Xuan Li +4 位作者 Zhi-Yang Yu Zhao-Yuan Meng Cheng Wang Zhi-Zheng Yang Hui-Yuan Wang 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第1期348-360,共13页
Due to the significant differences in the formation temperature and crystal structure between the primaryα-Mg and eutecticβ-Mg_(17)Al_(12),it is a great challenge to achieve simultaneous refinement of the primary an... Due to the significant differences in the formation temperature and crystal structure between the primaryα-Mg and eutecticβ-Mg_(17)Al_(12),it is a great challenge to achieve simultaneous refinement of the primary and eutectic phases in Mg-Al based alloys via heterogeneous nucleation.Surprisingly,we found that theα-Mg andβ-Mg_(17)Al_(12) in the AZ80 alloy can be simultaneously refined after 0.2 wt.%Sm addition,with the grain size decreasing from∼217±15μm to∼170±10μm and theβ-Mg_(17)Al_(12) morphology changing from a typical continuous network to a nod-like or spherical structure.The simultaneous refinement mechanism is investigated through solidification simulation,transmission electron microscopy(TEM),and differential thermal analysis(DTA).In the AZ80-0.2Sm alloy,many Al8Mn4Sm particles can be observed near the center of theα-Mg grains or inside theβ-Mg_(17)Al_(12).Crystallographic calculations further reveal that the Al8Mn4Sm has good crystallographic matching with both theα-Mg andβ-Mg_(17)Al_(12),so it possesses the potency to serve as heterogeneous nucleation sites for both phases.The promoted heterogeneous nucleation on the Al8Mn4Sm decreases the undercooling required by the nucleation of the primary and eutectic phases,which enhances the heterogeneous nucleation rate,thus causing the simultaneous refinement of theα-Mg andβ-Mg_(17)Al_(12).The orientation relationships between the Al8Mn4Sm and Mg/Mg_(17)Al_(12) are identified,which are[1210]_(Mg)//[010]_(Al8Mn4Sm),(1010)_(Mg)//(301)_(Al8Mn4Sm) and[112]_(Mg_(17)Al_(12))//[010]_(Al8Mn4Sm),(110)_(Mg_(17)Al_(12))//(301)_(Al8Mn4Sm),respectively.Furthermore,the refinement of theβ-Mg_(17)Al_(12) accelerates its dissolution during the solution treatment,which is beneficial for cost saving in industrial applications.Other Al8Mn4RE compounds such as Al8Mn4Y might have the same positive effect on the simultaneous refinement due to the similar physicochemical properties of rare earth elements.This work not only proves the possibility of simultaneously refining the primary and eutectic phases in Mg-Al based alloys via heterogeneous nucleation,but also provides new insights into the development of refiners for cast Mg alloys. 展开更多
关键词 Magnesium alloys Microstructure refinement Primaryα-Mg Eutecticβ-Mg_(17)Al_(12) Rare earth heterogeneous nucleation
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Effect of substrate micro-morphology on heterogeneous nucleation
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作者 Zhang Ying Wang Meng +1 位作者 Lin Xin Huang Weidong 《China Foundry》 SCIE CAS 2012年第3期234-238,共5页
The heterogeneous nucleation process of NH4Cl crystals from a NH4Cl-70wt.%H2O solution on rough chilling substrates was considered in this paper. Scratched and etched substrates of aluminum were prepared with differen... The heterogeneous nucleation process of NH4Cl crystals from a NH4Cl-70wt.%H2O solution on rough chilling substrates was considered in this paper. Scratched and etched substrates of aluminum were prepared with different surface morphologies. It was concluded that for nucleation to occur on a rough substrate surface, the wettability or the generally said roughness are not the key factors affecting the heterogeneous nucleation process. Rather the surface morphologies on the nanometer scale, which is close to the scale of the critical nucleation radius, are more important. 展开更多
关键词 grain refinement heterogeneous nucleation SUBSTRATE MICRO-MORPHOLOGY
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Experimental determination of grain density function of AZ91/SiC composite with different mass fractions of SiC and undercoolings using heterogeneous nucleation model 被引量:3
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作者 J.Lelito P.Zak +3 位作者 J.S.Suchy W.Krajewski A.L.Greer P.Darlak 《China Foundry》 SCIE CAS 2011年第1期101-106,共6页
The grain density,Nv,in the solid state after solidification of AZ91/SiC composite is a function of maximum undercooling,ΔT,of a liquid alloy.This type of function depends on the characteristics of heterogeneous nucl... The grain density,Nv,in the solid state after solidification of AZ91/SiC composite is a function of maximum undercooling,ΔT,of a liquid alloy.This type of function depends on the characteristics of heterogeneous nucleation sites and number of SiC present in the alloy.The aim of this paper was selection of parameters for the model describing the relationship between the grain density of primary phase and undercooling.This model in connection with model of crystallisation,which is based on chemical elements diffusion and grain interface kinetics,can be used to predict casting quality and its microstructure.Nucleation models have parameters,which exact values are usually not known and sometimes even their physical meaning is under discussion.Those parameters can be obtained after mathematical analysis of the experimental data.The composites with 0,1,2,3 and 4wt.% of SiC particles were prepared.The AZ91 alloy was a matrix of the composite reinforcement SiC particles.This composite was cast to prepare four different thickness plates.They were taken from the region near to the thermocouple,to analyze the undercooling for different composites and thickness plates and its influence on the grain size.The microstructure and thermal analysis gave set of values that connect mass fraction of SiC particles,and undercooling with grain size.These values were used to approximate nucleation model adjustment parameters.Obtained model can be very useful in modelling composites microstructure. 展开更多
关键词 heterogeneous nucleation mass fraction of SiC particles AZ91/SiC composite grain density mathematical modelling
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Surface modification of spherical LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2 with Al_2O_3 using heterogeneous nucleation process 被引量:4
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作者 杨志 李新海 +1 位作者 王志兴 朱勇军 《中国有色金属学会会刊:英文版》 CSCD 2007年第6期1319-1323,共5页
To improve the cycle stability at high voltage and high charge/discharge rate, spherical LiNi1/3Co1/3Mn1/3O2 was coated with Al2O3 by using heterogeneous nucleation process, and the physical and electrochemical proper... To improve the cycle stability at high voltage and high charge/discharge rate, spherical LiNi1/3Co1/3Mn1/3O2 was coated with Al2O3 by using heterogeneous nucleation process, and the physical and electrochemical properties were studied. The SEM images show that there is a uniform coating on the modified spherical LiNi1/3Co1/3Mn1/3O2. The electrochemical tests indicate that the properties of LiNi1/3Co1/3Mn1/3O2 coated with 0.5% aluminum oxide are the best. The initial capacities are 150 and 173 mA·h/g at the rate of 1C in the voltage range of 2.7-4.3 V and 2.7-4.6 V, respectively, and the discharge capacities maintain about 99% and 85% after 30 cycles, respectively. While those of the bare LiNi1/3Co1/3Mn1/3O2 are only 90% and 75%, respectively. The CV tests of LiNi1/3Co1/3Mn1/3O2 show that Al2O3-coating can restrain the oxide-reduction peak currents fading during the charge/discharge course. 展开更多
关键词 锂离子电池 LINI1/3CO1/3MN1/3O2 异类成核 三氧化二铝涂层
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Graphite Surface Modification by Heterogeneous Nucleation Process
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作者 CAO Ran LI Hongxia 《China's Refractories》 CAS 2006年第3期6-9,共4页
Flaky graphite particles were coated by ZrOCl2 · 8H2O as precursors by heterogeneous nucleation process. The effects of factors such as pH values ( 2. 4 - 5. 1 ), concentration of the precursor solution ( 0. 0... Flaky graphite particles were coated by ZrOCl2 · 8H2O as precursors by heterogeneous nucleation process. The effects of factors such as pH values ( 2. 4 - 5. 1 ), concentration of the precursor solution ( 0. 005 - 0. 1 mol · L^-1) , mixing method of graphite and precursor solution on the surface modification of graphite were studied. Result shows that :1 ) the preferable technical process for heterogeneous nucleation modified graphite is to mix the graphite suspension and precursor solution with concentration 0. 025 mol ·L^-1 and then drip ammonia water to adjust the pH value to 3.6 ; 2 ) By surface modification, the ZrO2 particles are evenly coated on graphite surface and therefore improve oxidation resistance and dispersion ability of graphite. 展开更多
关键词 GRAPHITE Surface modification heterogeneous nucleation ZIRCONIA Oxidation resistance
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Precipitation and Hetero-nucleation Effect of V(C,N) in V-Microalloyed Steel 被引量:2
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作者 李新城 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2008年第6期844-849,共6页
The precipitation behavior of V(C, N) in steels microalloyed with vanadium was researched using a thermal simulator during single-pass deformation at 800-750 ℃. The V(C, N) precipitates and its nucleation effect ... The precipitation behavior of V(C, N) in steels microalloyed with vanadium was researched using a thermal simulator during single-pass deformation at 800-750 ℃. The V(C, N) precipitates and its nucleation effect on ferrite were investigated by TEM and EDS. The experimental results show that there are two remarkable heterogeneous nucleation effects of V(C, N) particles precipitated before γ →/ α phase change: primary reason is that high coherency between V(C, N) and ferrite promotes V(C, N) to become a nucleating center of intragranular ferrite; secondary reason is that the coarsening of V(C, N) causes locally solute-poor region in austenite, thus expedites the nucleation of intragranular ferrites further. Furthermore, the relationship between the size and shape of V(C, N) was studied, and identification method was provided for distinguishing interphase precipitation and general precipitation to avoid erroneous judgment and misguide. 展开更多
关键词 V(C N) heterogeneous nucleation deformation enhanced ferrite transformation
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Revealing the nucleation event of Mg-Al alloy induced by Fe impurity 被引量:3
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作者 Hengbin Liao Liling Mo +2 位作者 Xiong Zhou Zhizhong Yuan Jun Du 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2022年第7期1317-1321,共5页
This study revealed the nucleation event and grain refinement mechanism of Mg-Al alloy induced by Fe impurity.The following orientation relationship was observed between Al-Fe particle andα-Mg matrix in the Mg-3Al al... This study revealed the nucleation event and grain refinement mechanism of Mg-Al alloy induced by Fe impurity.The following orientation relationship was observed between Al-Fe particle andα-Mg matrix in the Mg-3Al alloy containing Fe impurity using a focused ion beam aided transmission electron microscope technique:(1^(-)011)[011^(-)1]_(Mg)//(011^(-))[011]_(Al_(2)Fe).Mg-3Al alloy was inoculated by adding 0.02wt%Fe to verify the nucleating potency of the Al_(2)Fe phase forα-Mg grain.The results indicated that Mg-3Al alloy was effectively refined with an average grain size declining from 1135 to 540μm.Among the potential Al-Fe phases of Mg-3Al-0.02Fe alloy,only the precipitation of the Al_(2)Fe phase occurs earlier than that ofα-Mg grain,and the Al_(2)Fe phase is stable in the nucleation stage ofα-Mg grain.Therefore,the Al_(2)Fe particle is the only available nucleating site for Mg-Al alloy with Fe impurity.The heterogeneous nucleation event ofα-Mg grain on the Al_(2)Fe particle is responsible for the grain refinement of Mg-3Al alloy inoculated by Fe. 展开更多
关键词 grain refinement Mg-Al alloy Al-Fe particle heterogeneous nucleation
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Influence of reservoir heterogeneity on immiscible water-alternating-CO_(2)flooding:A case study
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作者 Peifeng Jia Chuanzhi Cui +1 位作者 Zhongwei Wu Dawei Yan 《Energy Geoscience》 EI 2024年第3期77-84,共8页
Currently,limited studies of immiscible water-alternating-CO_(2)(imWACO_(2))flooding focus on the impact of reservoir heterogeneity on reservoir development outcomes.Given this,using the heterogeneous reservoirs in th... Currently,limited studies of immiscible water-alternating-CO_(2)(imWACO_(2))flooding focus on the impact of reservoir heterogeneity on reservoir development outcomes.Given this,using the heterogeneous reservoirs in the Gao 89-1 block as a case study,this study conducted slab core flooding experiments and numerical simulations to assess the impact of reservoir heterogeneity on imWACO_(2)flooding efficiency.It can be concluded that imWACO_(2)flooding can enhance the sweep volume and oil recovery compared to continuous CO_(2)flooding.As the permeability difference increases,the difference in the swept volume between zones/layers with relatively high and low permeability increases.To optimize the exploitation of reservoirs in the Gao 89-1 block,the optimal timing and CO_(2)injection rate for imWACO_(2)flooding are determined at water cut of 40%and 10000 m^(3)/d,respectively.A short injection-production semi-period,combined with multiple cycles of water and CO_(2)injection alternations,is beneficial for enhanced oil recovery from imWACO_(2)flooding. 展开更多
关键词 Immiscible water-alternating-CO_(2)flooding Gao 89-1 block Slab experiment Numerical simulation Reservoir heterogeneity
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Transient liquid assisted nucleation mechanism of YBa_2Cu_3O_(7-δ) in coated conductor films derived by BaF_2 process 被引量:1
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作者 谷朝辉 杨文涛 +6 位作者 白传易 郭艳群 鲁玉明 刘志勇 路齐 舒刚强 蔡传兵 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第9期413-418,共6页
It is significant for low-cost preparation of YBa2Cu3O7-δ(YBCO) coated conductors to make clear the mechanism of orientation, copper segregation, and nucleation density in BaF2-derived YBCO crystallization. In the ... It is significant for low-cost preparation of YBa2Cu3O7-δ(YBCO) coated conductors to make clear the mechanism of orientation, copper segregation, and nucleation density in BaF2-derived YBCO crystallization. In the present work,a distinct nucleation mechanism was proposed based on a transient liquid phase induced by the size effect as well as near-equilibrium assumption. With this scheme the nucleation of YBCO prepared by metal–organic deposition(MOD) or the physical vapor deposition BaF2 process was semi-quantitatively analyzed, revealing that the direct driving force for nucleation is YBCO supersaturation in the liquid phase. The theoretical analysis on the nucleation orientation portion is evidenced by the experimental result. 展开更多
关键词 YBa_2Cu_3O_(7-δ) coated conductor nucleation
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Quaternary phosphonium polymer-supported dual-ionically bound[Rh(CO)I_(3)]^(2-)catalyst for heterogeneous ethanol carbonylation
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作者 Zhou Ren Yang Liu +4 位作者 Yuan Lyu Xiangen Song Changyong Zheng Zheng Jiang Yunjie Ding 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2021年第4期606-617,共12页
A single-Rh-site catalyst(Rh-TPISP)that was ionically-embedded on a P(V)quaternary phosphonium porous polymer was evaluated for heterogeneous ethanol carbonylation.The[Rh(CO)I_(3)]^(2-)unit was proposed to be the acti... A single-Rh-site catalyst(Rh-TPISP)that was ionically-embedded on a P(V)quaternary phosphonium porous polymer was evaluated for heterogeneous ethanol carbonylation.The[Rh(CO)I_(3)]^(2-)unit was proposed to be the active center of Rh-TPISP for the carbonylation reaction based on detailed Rh L3-edge X-ray absorption near edge structure(XANES),X-ray photoelectron spectroscopy(XPS),and Rh extended X-ray absorption fine structure(EXAFS)analyses.As the highlight of this study,Rh-TPISP displayed distinctly higher activity for heterogeneous ethanol carbonylation than the reported catalytic systems in which[Rh(CO)_(2)I_(2)]^(-)is the traditional active center.A TOF of 350 h^(-1)was obtained for the reaction over[Rh(CO)I_(3)]^(2-),with>95%propionyl selectivity at 3.5 MPa and 468 K.No deactivation was detected during a near 1000 h running test.The more electron-rich Rh center was thought to be crucial for explaining the superior activity and selectivity of Rh-TPISP,and the formation of two ionic bonds between[Rh(CO)I_(3)]^(2-)and the cationic P(V)framework([P]^(+))of the polymer was suggested to play a key role in firmly immobilizing the active species to prevent Rh leaching. 展开更多
关键词 heterogeneous ethanol carbonylation Single-site catalyst Carbonylation active center [Rh(CO)I_(3)]^(2-) Ultrastable dual-ionically bound immobilization Porous ionic polymer
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Enhancing reversible hydrogen storage performance of 2LiBH_(4)–MgH_(2)via in-situ building heterogeneous nucleation sites
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作者 Wei Chen Ya-Hui Sun +2 位作者 Tian Xu Xue-Bin Yu Guang-Lin Xia 《Rare Metals》 SCIE EI CAS CSCD 2024年第9期4367-4376,共10页
2LiBH_(4)-MgH_(2)composite is one of the most attractive reactive hydride composites with a theoretic hydrogen capacity of 10.8 wt%.However,the large nucleation restriction of MgB_(2)during the second step of dehydrog... 2LiBH_(4)-MgH_(2)composite is one of the most attractive reactive hydride composites with a theoretic hydrogen capacity of 10.8 wt%.However,the large nucleation restriction of MgB_(2)during the second step of dehydrogenation results in sluggish hydrogen storage kinetics and high operating temperature,which hinders its practical application as on-board hydrogen storage materials.Herein,Al3Ti doped Al nanoparticles(AT NPs)are prepared by a facile chemical reduction reaction to improve the hydrogen storage performance of 2LiBH_(4)-MgH_(2)composite.During the initial H_(2)desorption process,MgAlB_(4)and TiB_(2)that have identical crystal structure and low d-value mismatch with MgB_(2)resulting from the reaction between AT NPs and 2LiBH_(4)-MgH_(2)composite serve as effective nucleation sites for the formation of MgB_(2).As a result,the apparent activation energy of the two-step H_(2)desorption of AT NPs doped 2LiBH_(4)-MgH_(2)composite are notably decreased to(110.0±5.9)and(119.6±1.4)kJ·mol^(-1),which is 55.5 and 33.5 kJ·mol^(-1)lower than that of the undoped sample.More importantly,a reversible hydrogen storage capacity of 9.2 wt%after 10cycles of H_(2)desorption and adsorption could be achieved,corresponding to a capacity retention rate of 99%.The building of reactive bimetallic catalyst towards in situ formation of heterogeneous nucleation sites provides a new strategy for improving the hydrogen storage performance of reactive hydride composites. 展开更多
关键词 Reversible hydrogen storage Reactive hydride composites Catalytic effects heterogeneous nucleation
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Sc和Si相互作用对铸造Al-Si-Sc合金组织和性能的影响
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作者 周荣虎 周鹏飞 《铸造》 CAS 2024年第5期612-620,共9页
通常在铸造Al-Si合金加入Sc来改善合金的性能,但是Si和Sc的相互作用对合金组织和性能影响仍需要进一步深入研究。本文研究了不同含量的Si和Sc对合金组织和性能的影响,结果表明,Sc通过原位形成初生Al_(3)Sc作为α-Al异质形核质点从而细化... 通常在铸造Al-Si合金加入Sc来改善合金的性能,但是Si和Sc的相互作用对合金组织和性能影响仍需要进一步深入研究。本文研究了不同含量的Si和Sc对合金组织和性能的影响,结果表明,Sc通过原位形成初生Al_(3)Sc作为α-Al异质形核质点从而细化α-Al晶粒;在凝固过程中,共晶反应生成了网格状AlSi_(2)Sc_(2)相,包晶反应形成了块状AlSi_(2)Sc_(2)相;两种AlSi_(2)Sc_(2)相都会消耗合金中Sc原子,从而降低了Al_(3)Sc的细化效果;Sc还变质共晶Si为更有序的纤维/片状结构,适当的Si与Sc的比可以避免AlSi_(2)Sc_(2)的形成;Al-6Si中Sc含量从0.3%增加至1%时,抗拉强度和屈服强度均上升,但由于AlSi_(2)Sc_(2)相的存在,其伸长率下降;当Sc含量为1%、Si含量从6%降至3%时,抗拉强度、屈服强度和伸长率分别上升2%、12%和21%,主要是凝固过程中析出了Al_(3)Sc而非AlSi_(2)Sc_(2)相。最后,还讨论了Si-Sc交互作用对组织演变的机制。 展开更多
关键词 Al-Si-Sc合金 组织 异质形核 变质
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Nanoparticle nucleation and coagulation in a mixing layer 被引量:4
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作者 Jian-Zhong Lin Yan-Hua Liu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第4期521-529,共9页
Numerical simulation of nanoparticle nucleation and coagulation in a mixing layer with sulfuric acid vapor binary system is performed using the large eddy simulation and the direct quadrature method of moment. The dis... Numerical simulation of nanoparticle nucleation and coagulation in a mixing layer with sulfuric acid vapor binary system is performed using the large eddy simulation and the direct quadrature method of moment. The distributions of number concentration, volume concentration, and average diameter of nanoparticles are obtained. The results show that the coherent structures have an important effect on the distributions of number concentration, volume concentration and average diameter of nanoparticles via continuously transporting and diffusing the nanoparticles to the area of low particle concentration. In the streamwise direction, the number concentration of nanoparticles decreases, while the volume concentration and the average diameter increase. The distributions of number concentration, volume concentration and average diameter of nanoparticles are spatially inhomogeneous. The characteristic time of nucleation is shorter than that of coagulation. The nucleation takes place more easily in the area of low temperature because where the number concentration of nanoparticles is high, while the intensity of coagulation is mainly affected by the number concentration. Both nucleation and coagulation result in the variation of average diameter of nanoparticles. 展开更多
关键词 Nanoparticles nucleation - Coagulation Mixing layer Direct quadrature method of moment
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Characteristics of lateral vehicular interactions in heterogeneous traffic with weak lane discipline 被引量:1
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作者 Anuj Kishor Budhkar Akhilesh Kumar Maurya 《Journal of Modern Transportation》 2017年第2期74-89,共16页
Heterogeneous traffic conditions prevail in developing countries. Vehicles maintain weak lane discipline which increases lateral interactions of vehicles significantly. It is necessary to study these interactions in t... Heterogeneous traffic conditions prevail in developing countries. Vehicles maintain weak lane discipline which increases lateral interactions of vehicles significantly. It is necessary to study these interactions in the form of maintained lateral gaps for modeling this traffic scenario. This paper aims at determining lateral clearances maintained by different vehicle types while moving in a heterogeneous traffic stream during overtaking. These data were collected using an instrumented vehicle which runs as a part of the stream. Variation of obtained clearance with average speed of interacting vehicles is studied and modeled. Different instrumented vehicles of various types are developed using (1) ultrasonic sensors fixed on both sides of vehicle, which provide inter-vehicular lateral distance and relative speed; and (2) GPS device with cameras, which provides vehicle type and speed of interacting vehicles. They are driven on different roads in six cities of India, to measure lateral gaps maintained with different interacting vehicles at different speeds. Relationships between lateral gaps and speed are modeled as regression lines with positive slopes and beta-distributed residuals. Nature of these graphs (i.e., slopes, intercepts, residuals) are also evaluated and compared for different interacting vehicle-type pairs. It is observed that similar vehicle pairs maintain less lateral clearance than dissimilar vehicle pairs. If a vehicle interacts with two vehicles (one on each side) simultaneously, lateral clearance is reduced and safety of the vehicles is compromised. The obtained relationships can be used for simulating lateral clearance maintaining behavior of vehicles in heterogeneous traffic. 展开更多
关键词 Ultrasonic sensors - heterogeneous traffic Lateral gaps Lateral vehicular interactions Weak lane discipline
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Nucleation Thermodynamics inside Micro/nanocavity
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作者 Qiuxiang LIU Yanjuan ZHU +1 位作者 Guowei YANG Qibin YANG 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2008年第2期183-186,共4页
A thermodynamic approach at the nanometer scale was performed for the heterogeneous nucleation inside nanocavity, and an analytical expression of the critical energy of nucleation was evaluated considering a rough bal... A thermodynamic approach at the nanometer scale was performed for the heterogeneous nucleation inside nanocavity, and an analytical expression of the critical energy of nucleation was evaluated considering a rough ball nucleus nucleating inside nanocavity. Compared with the case of the nucleation locating on planar or convex substrate, the critical energy of nucleation inside the concave substrate is the smallest. Based on the thermodynamic and kinetic analyses, at low supersaturation, the smaller the curvature radius of cavity and/or the smaller the contact angle, the smaller the critical energy of nucleation, and the larger the nucleation rate. At high supersaturation, the nucleation rate increases with increasing the contact angle and/or increasing the curvature radius of cavity. In this way, at the low supersaturation, the heterogeneous nucleation rate is larger than the homogeneous one, as the nucleation rate is mainly determined by the heterogeneous nucleation. At the high supersaturation, the heterogeneous nucleation rate is smaller than the homogeneous one, as the nucleation rate is mainly determined by the homogeneous nucleation. 展开更多
关键词 heterogeneous nucleation nucleation barrier nucleation rate
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Sc对Al-8.5Zn-2.3Mg-2.4Cu合金组织与性能的影响
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作者 成义锐 孙小涵 +3 位作者 贺永东 赵亿坤 杜玉峰 梁飞龙 《矿冶工程》 CAS 北大核心 2024年第5期142-147,共6页
研究了Sc对Al-8.5Zn-2.3Mg-2.4Cu合金组织与性能的影响。结果表明:Al-Zn-Mg-Cu铸态合金中添加Sc后,合金晶粒尺寸明显减小;Sc含量(质量分数)由0增加至0.4%时,合金晶粒尺寸由107.7μm减小至49.96μm,硬度由116.8HV增加至130.2HV。经大变... 研究了Sc对Al-8.5Zn-2.3Mg-2.4Cu合金组织与性能的影响。结果表明:Al-Zn-Mg-Cu铸态合金中添加Sc后,合金晶粒尺寸明显减小;Sc含量(质量分数)由0增加至0.4%时,合金晶粒尺寸由107.7μm减小至49.96μm,硬度由116.8HV增加至130.2HV。经大变形量热轧处理后进行470℃×1 h固溶处理发现,相较未添加Sc的合金,含Sc合金位错密度增大;添加0.4%Sc的合金再结晶率由92.4%降低至45.7%,合金的再结晶行为受到抑制。经120℃×24 h时效处理后,添加0.4%Sc的Al-Zn-Mg-Cu合金中观察到大量弥散分布的圆球状Al_(3)Sc粒子和短棒状η′(MgZn_(2))粒子,通过绘制与α(Al)共格或半共格的Al_(3)Sc-MgZn_(2)晶体结构模型,可推测出Al_(3)Sc粒子为η′(MgZn_(2))相提供异质形核位点,促进其形核,对合金时效析出强化有促进作用。 展开更多
关键词 微合金化 AL-ZN-MG-CU合金 再结晶 Al3Sc粒子 异质形核位点 析出强化
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Unlock the full potential of carbon cloth-based scaffolds towards magnesium metal storage via regulation on magnesiophilicity and surface geometric structure
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作者 Jing Liu Min Wang +4 位作者 Zhonghua Zhang Jinlei Zhang Yitao He Zhenfang Zhou Guicun Li 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第3期423-434,I0010,共13页
The development of rechargeable magnesium(Mg) batteries is of practical significance to upgrade the electric energy storage devices due to exceptional capacity and abundant resources of Mg-metal anode.However,the reve... The development of rechargeable magnesium(Mg) batteries is of practical significance to upgrade the electric energy storage devices due to exceptional capacity and abundant resources of Mg-metal anode.However,the reversible Mg electrochemistry suffers from unsatisfied rate capability and lifespan,mainly caused by non-uniform distribution of electrodeposits.In this work,a fresh design concept of threedimensional carbon cloths scaffolds is proposed to overcome the uncontrollable Mg growth via homogenizing electric field and improving magnesiophilicity.A microscopic smooth and nitrogen-containing defective carbonaceous layer is constructed through a facile pyrolysis of ZIF8 on carbon cloths.As revealed by finite element simulation and DFT calculation results,the smooth surface endows with uniform electric field distribution and simultaneously the nitrogen-doping species enable good magnesiophilicity of scaffolds.The fine and uniform Mg nucleus as well as the inner electrodeposit behavior are also disclosed.As a result,an exceptional cycle life of 500 cycles at 4.0 mA cm^(-2) and 4.0 mA h cm^(-2) is firstly realized to our best knowledge.Besides,the functional scaffolds can be cycled for over 2200 h at 2.0 mA cm^(-2) under a normalized capacity of 5.0 mA h cm^(-2),far exceeding previous results.This work offers an effective approach to enable the full potential of carbon cloths-based scaffolds towards metal storage for next generation battery applications. 展开更多
关键词 Magnesium metal anodes ELECTRODEPOSITION heterogeneous nucleation
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Enhanced Grain Refining Effect of Mg–Zr Master Alloy on Magnesium Alloys via a Synergistic Strategy Involving Heterogeneous Nucleation and Solute‑Driven Growth Restriction
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作者 Gang Zeng Hong Liu +2 位作者 Jing‑Peng Xiong Jian‑Long Li Yong Liu 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2024年第8期1354-1366,共13页
Zirconium(Zr)emerges as the most effective grain refiner for magnesium(Mg)alloys incorporating Zr.Typically,Zr is introduced in the form of an Mg–Zr master alloy.However,within Mg–Zr master alloys,Zr predominantly e... Zirconium(Zr)emerges as the most effective grain refiner for magnesium(Mg)alloys incorporating Zr.Typically,Zr is introduced in the form of an Mg–Zr master alloy.However,within Mg–Zr master alloys,Zr predominantly exists in a particle form,which tends to aggregate due to attractive van der Waals forces.The clustered Zr is prone to settling,thereby reducing its refining impact on Mg alloys.In this work,a combined pretreatment process for Mg–Zr master alloys was proposed,encompassing the introduction of a physical field to intervene the agglomeration of particle Zr and the employ of high-temperature dissolution and peritectic reactions to promote the solid solution of Zr.The results demonstrate that the particle Zr within the pretreated Mg–Zr master alloy is effectively dispersed and refined,and greater solute Zr levels can be achieved.The subsequent grain refinement ability was studied on a typical Mg–6Zn–0.6Zr(wt%)alloy.The outcome highlights that an improvement in the grain refinement efficacy(32.4%)of Mg–Zr master alloys was obtained with a holding time of 60 min.The pretreated Mg–Zr master alloy significantly augments the efficiency of grain refinement for Mg alloys through a synergistic strategy involving heterogeneous nucleation and solute-driven growth restriction.The crucial factor in achieving effective grain refinement of Zr in Mg alloys lies in regulating the presence and morphology of Zr in the Mg–Zr master alloy,distinguishing between particle Zr and solute Zr.This study introduces a novel method for developing more efficient Mg–Zr refiners. 展开更多
关键词 Magnesium alloy Mg-Zr master alloy Grain refinement heterogeneous nucleation Solute-driven growth restriction Synergistic strategy
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Novel miR-490-3p/hnRNPA1-b/PKM2 axis mediates the Warburg effect and proliferation of colon cancer cells via the PI3K/AKT pathway
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作者 Xiang-Hui Wan Guo-Bing Jin +8 位作者 Qun Yang Ji-Long Hu Zhi-Liang Liu Jun Rao Can Wen Peng-Ling Li Xi-Mei Yang Bo Huang Xiao-Zhong Wang 《World Journal of Gastrointestinal Oncology》 SCIE 2024年第5期2038-2059,共22页
BACKGROUND Heterogeneous ribonucleoprotein A1(hnRNPA1)has been reported to enhance the Warburg effect and promote colon cancer(CC)cell proliferation,but the role and mechanism of the miR-490-3p/hnRNPA1-b/PKM2 axis in ... BACKGROUND Heterogeneous ribonucleoprotein A1(hnRNPA1)has been reported to enhance the Warburg effect and promote colon cancer(CC)cell proliferation,but the role and mechanism of the miR-490-3p/hnRNPA1-b/PKM2 axis in CC have not yet been elucidated.AIM To investigate the role and mechanism of a novel miR-490-3p/hnRNPA1-b/PKM2 axis in enhancing the Warburg effect and promoting CC cell proliferation through the PI3K/AKT pathway.METHODS Paraffin-embedded pathological sections from 220 CC patients were collected and subjected to immunohistochemical analysis to determine the expression of hnRNPA1-b.The relationship between the expression values and the clinicopathological features of the patients was investigated.Differences in mRNA expression were analyzed using quantitative real-time polymerase chain reaction,while differences in protein expression were analyzed using western blot.Cell proliferation was evaluated using the cell counting kit-8 and 5-ethynyl-2’-deoxyuridine assays,and cell cycle and apoptosis were detected using flow cytometric assays.The targeted binding of miR-490-3p to hnRNPA1-b was validated using a dual luciferase reporter assay.The Warburg effect was evaluated by glucose uptake and lactic acid production assays.RESULTS The expression of hnRNPA1-b was significantly increased in CC tissues and cells compared to normal controls(P<0.05).Immunohistochemical results demonstrated significant variations in the expression of the hnRNPA1-b antigen in different stages of CC,including stage I,II-III,and IV.Furthermore,the clinicopathologic characterization revealed a significant correlation between hnRNPA1-b expression and clinical stage as well as T classification.HnRNPA1-b was found to enhance the Warburg effect through the PI3K/AKT pathway,thereby promoting proliferation of HCT116 and SW620 cells.However,the proliferation of HCT116 and SW620 cells was inhibited when miR-490-3p targeted and bound to hnRNPA1-b,effectively blocking the Warburg effect.CONCLUSION These findings suggest that the novel miR-490-3p/hnRNPA1-b/PKM2 axis could provide a new strategy for the diagnosis and treatment of CC. 展开更多
关键词 heterogeneous ribonucleoprotein A1-b MiR-490-3p Colon cancer Alternative splicing Warburg effect
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7YSZ coating prepared by PS-PVD based on heterogeneous nucleation 被引量:12
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作者 Ziqian DENG Xiaofeng ZHANG +4 位作者 Kesong ZHOU Min LIU Chunming DENG Jie MAO Zhikun CHEN 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2018年第4期820-825,共6页
Plasma spray-physical vapor deposition(PS-PVD) as a novel coating process based on low-pressure plasma spray(LPPS) has been significantly used for thermal barrier coatings(TBCs).A coating can be deposited from l... Plasma spray-physical vapor deposition(PS-PVD) as a novel coating process based on low-pressure plasma spray(LPPS) has been significantly used for thermal barrier coatings(TBCs).A coating can be deposited from liquid splats, nano-sized clusters, and the vapor phase forming different structured coatings, which shows obvious advantages in contrast to conventional technologies like atmospheric plasma spray(APS) and electron beam-physical vapor deposition(EBPVD). In addition, it can be used to produce thin, dense, and porous ceramic coatings for special applications because of its special characteristics, such as high power, very low pressure, etc. These provide new opportunities to obtain different advanced microstructures, thus to meet the growing requirements of modern functional coatings. In this work, focusing on exploiting the potential of gas-phase deposition from PS-PVD, a series of 7 YSZ coating experiments with various process conditions was performed in order to better understand the deposition process in PS-PVD, where coatings were deposited on different substrates including graphite and zirconia. Meanwhile, various substrate temperatures were investigated for the same substrate. As a result, a deposition mechanism of heterogeneous nucleation has been presented showing that surface energy is an important influencing factor for coating structures. Besides, undercooling of the interface between substrate and vapor phase plays an important role in coating structures. 展开更多
关键词 7YSZ Deposition mechanism heterogeneous nucleation PS-PVD TBC
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