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Effects of fiber curvature on the microstructure of the interfacial transition zone in fresh concrete

CHEN Huisu, SUN Wei, ZHAO Qingxin, L. J. Sluys, P. Stroeven

《结构与土木工程前沿(英文)》 2007年 第1卷 第1期   页码 99-106 doi: 10.1007/s11709-007-0010-6

摘要: The study on the interfacial transition zone (ITZ) of concrete has received lots of attention in the last decade. However, no information is available on the influence of the curvature of a rigid surface on the microstructure of ITZ. This paper employed computer simulation technology to study the influence of fiber curvature on the initial microstructure of ITZ in concrete. For the sake of simplification, the investigation was first focused on the mono-size spherical particle packing system around a cylindrical fiber with different diameters. An algorithm of serial cylindrical sectioning was developed. The curve of the solid volume fraction versus the distance to the surface of the fiber was used as a parameter to characterize the microstructure of the ITZ. Then, the influence of the ratio of fiber diameter to particle diameter on the initial ITZ s microstructure was studied. These curves were compared with the ones from flat aggregate surface on which mono-size spherical particles were packed. Furthermore, the multi-size spherical particles system was further investigated. The simulation results demonstrate that no matter whether the spherical particles system is mono-size or multi-size, the fresh ITZ s microstructure is irrelevant to the curvature of the fiber. The shape of the curve of solid volume fraction versus the distance from the surface of the fiber is similar to that around a flat aggregate surface. In all cases, the horizontal coordinates of the first peak of the curves are located at around half the mean weight diameter of the particles. The thickness of ITZ reduces slightly with the decrease in water/cement ratio. Therefore, one may use the ITZ s microstructure around a flat aggregate surface to represent the ITZ s microstructure around a cylindrical fiber in the fresh state, and vice versa.

关键词: diameter     initial microstructure     influence     surface     spherical particle    

纳米工程混凝土界面过渡区的纳米力学特征 Article

王欣悦, 董素芬, 李镇明, 韩宝国, 欧进萍

《工程(英文)》 2022年 第17卷 第10期   页码 99-109 doi: 10.1016/j.eng.2020.08.025

摘要:

本研究利用纳米压痕试验和统计学方法研究了纳米填料对水泥石与骨料间界面过渡区(interfacial transition zone, ITZ

关键词: 混凝土     纳米填料     界面过渡区     纳米压痕     微观力学分析     纳米中心效应    

The ITZ microstructure, thickness, porosity and its relation with compressive and flexural strength of cement mortar; influence of cement fineness and water/cement ratio

《结构与土木工程前沿(英文)》 2022年 第16卷 第2期   页码 191-201 doi: 10.1007/s11709-021-0792-y

摘要: A new insight into the interfacial transition zone (ITZ) in cement mortar specimens (CMSs) that is influenced by cement fineness is reported. The importance of cement fineness in ITZ characterizations such as morphology and thickness is elucidated by backscattered electron images and by consequences to the compressive (Fc) and flexural strength (Ff), and porosity at various water/cement ratios. The findings indicate that by increasing the cement fineness the calcium silicate hydrate formation in the ITZ is favored and that this can refine the pore structures and create a denser and more homogeneous microstructure. By increasing cement fineness by about 25% of, the ITZ thickness of CMSs was reduced by about 30% and Fc was increased by 7%–52% and Ff by 19%–40%. These findings illustrate that the influence of ITZ features on the mechanical strength of CMSs is mostly related to the cement fineness and ITZ microstructure.

关键词: cement fineness     interfacial transition zone     compressive and flexural strength    

碱激发矿渣混凝土的水化特性及微观结构研究进展 Review

傅强,卜梦鑫, 张兆瑞, 许文瑞, 元强, 牛荻涛

《工程(英文)》 2023年 第20卷 第1期   页码 162-179 doi: 10.1016/j.eng.2021.07.026

摘要:

碱激发矿渣混凝土(alkali-activated slag concrete, AASC)是一种新型的绿色建材,与普通硅酸盐混凝土相比,制备AASC所产生的CO2仅为普通硅酸盐混凝土(ordinary Portland cement concrete, OPCC)的1/5;另外,AASC促进了矿渣等废弃物的再利用,节约了资源,扩大了矿渣的使用范围。本文根据AASC的相关研究,分析总结了AASC的水化特性以及界面过渡区、孔结构等微观结构的研究进展。讨论了矿渣成分、碱激发剂种类及其用量、养护条件对AASC的水化特性和微观结构的影响。目前关于AASC微观结构的研究成果相对较少,相关结论还未完全统一,而且,AASC的发展还存在很多制约因素(如矿渣原料成分复杂、收缩变形较大、流动性差等),因此,还需要进一步的深入研究。

关键词: 碱激发矿渣混凝土     水化特性     孔结构     界面过渡区     微观结构    

effects of mismatch fracture properties in encapsulation-based self-healing concrete using cohesive-zone

Luthfi Muhammad MAULUDIN, Chahmi OUCIF, Timon RABCZUK

《结构与土木工程前沿(英文)》 2020年 第14卷 第3期   页码 792-801 doi: 10.1007/s11709-020-0629-0

摘要: Finite element analysis is developed to simulate the breakage of capsule in capsule-based self-healing concrete. A 2D circular capsule with different core-shell thickness ratios embedded in the mortar matrix is analyzed numerically along with their interfacial transition zone. Zero-thickness cohesive elements are pre-inserted into solid elements to represent potential cracks. This study focuses on the effects of mismatch fracture properties, namely fracture strength and energy, between capsule and mortar matrix into the breakage likelihood of the capsule. The extensive simulations of 2D specimens under uniaxial tension were carried out to investigate the key features on the fracture patterns of the capsule and produce the fracture maps as the results. The developed fracture maps of capsules present a simple but valuable tool to assist the experimentalists in designing appropriate capsule materials for self-healing concrete.

关键词: self-healing concrete     interfacial zone     capsule materials     cohesive elements     fracture maps    

The effects of interfacial strength on fractured microcapsule

Luthfi Muhammad MAULUDIN, Chahmi OUCIF

《结构与土木工程前沿(英文)》 2019年 第13卷 第2期   页码 353-363 doi: 10.1007/s11709-018-0469-3

摘要: The effects of interfacial strength on fractured microcapsule are investigated numerically. The interaction between crack and microcapsule embedded in mortar matrix is modeled based on cohesive approach. The microcapsules are modelled with variation of core-shell thickness ratio and potential cracks are represented by pre-inserted cohesive elements along the element boundaries of the mortar matrix, microcapsules core, microcapsule shell, and at the interfaces between these phases. Special attention is given to the effects of cohesive fracture on the microcapsule interface, namely fracture strength, on the load carrying capacity and fracture probability of the microcapsule. The effect of fracture properties on microcapsule is found to be significant factor on the load carrying capacity and crack propagation characteristics. Regardless of core-shell thickness ratio of microcapsule, the load carrying capacity of self-healing material under tension increases as interfacial strength of microcapsule shell increases. In addition, given the fixed fracture strength of the interface of microcapsule shell, the higher the ratio core-shell thickness, the higher the probability of microcapsules being fractured.

关键词: interfacial strength     cohesive elements     microcapsule     core-shell thickness ratio     fracture properties    

Applying the multi-zone model in predicting the operating range of HCCI engines

Ming JIA, Maozhao XIE, Zhijun PENG,

《能源前沿(英文)》 2010年 第4卷 第3期   页码 414-423 doi: 10.1007/s11708-010-0108-8

摘要: In this paper, a multi-zone model is developed to predict the operating range of homogeneous charge compression ignition (HCCI) engines. The boundaries of the operating range were determined by knock (presented by ringing intensity), partial burn (presented by combustion efficiency), and cycle-to-cycle variations (presented by the sensitivity of indicated mean effective pressure to initial temperature). By simulating an HCCI engine fueled with iso-octane, the knock and cycle-to-cycle variations predicted by the model showed satisfactory agreement with measurements made under different initial temperatures and equivalence ratios; the operating range was also well reproduced by the model. Furthermore, the model was applied to predict the operating range of the HCCI engine under different engine speeds by varying the intake temperatures and equivalence ratios. The potential to extend the operating range of the HCCI engine through two strategies, i.e., variable compression ratio and intake pressure boosting, was then investigated. Results indicate that the ignition point can be efficiently controlled by varying the compression ratio. A low load range can be extended by increasing the intake temperature while reducing the compression ratio. Higher intake temperatures and lower compression ratios can also extend the high load range. Boosting intake pressure is helpful in controlling the combustion of the HCCI engine, resulting in an extended high load range.

关键词: homogeneous charge compression ignition (HCCI) engine     multi-zone     operating range    

Construction of interfacial dynamic bonds for high performance lignin/polymer biocomposites

《化学科学与工程前沿(英文)》 2023年 第17卷 第10期   页码 1372-1388 doi: 10.1007/s11705-023-2302-3

摘要: Lignin is the largest natural aromatic biopolymer, but usually treated as industrial biomass waste. The development of lignin/polymer biocomposites can promote the high value utilization of lignin and the greening of polymers. However, the weak interfacial interaction between industrial lignin and polymer induces poor compatibility and serious agglomeration in polymer owing to the strong intermolecular force of lignin. As such, it is extremely difficult to prepare high performance lignin/polymer biocomposites. Recently, we proposed the strategy of in situ construction of interfacial dynamic bonds in lignin/polymer composites. By taking advantage of the abundant oxygen-containing polar groups of lignin, we inserted dynamic bonding connection such as hydrogen bonds and coordination bonds into the interphase between lignin and the polymer matrix to improve the interfacial interactions. Meanwhile, the natural amphiphilic structure characteristics of lignin were utilized to construct the hierarchical nanophase separation structure in lignin/polymer composites. The persistent problems of poor dispersity and interfacial compatibility of lignin in the polymer matrix were effectively solved. The lignin-modified polymer composites achieved simultaneously enhanced strength and toughness. This concise review systematically summarized the recent research progress of our group toward building high-performance lignin/polymer biocomposites through the design of interfacial dynamic bonds (hydrogen bonds, coordination bonds, and dynamic covalent bonds) between lignin and different polymer systems (polar plastics, rubber, polyurethane, hydrogels, and other polymers). Finally, the future development direction, main challenges, and potential solutions of lignin application in polymers were presented.

关键词: lignin     polymer     interfacial dynamic bonds    

蛇绿岩型金刚石——探索深部碳循环的新窗口 Review

连东洋, 杨经绥

《工程(英文)》 2019年 第5卷 第3期   页码 406-420 doi: 10.1016/j.eng.2019.02.006

摘要: 青松矿包裹体(一种立方晶系的氮化硼)以及TiO2 II(金红石的高压相矿物)等矿物的发现指示铬铁矿形成的温压条件可能达到10~15 GPa、约1300 ℃,深度达大于380 km 的地幔转换带(mantle transitionzone,MTZ)深度。

关键词: 蛇绿岩型金刚石     柯石英     斯石英     豆荚状铬铁矿     地幔过渡带    

Epithelial-to-mesenchymal transition in cancer: complexity and opportunities

Yun Zhang, Robert A. Weinberg

《医学前沿(英文)》 2018年 第12卷 第4期   页码 361-373 doi: 10.1007/s11684-018-0656-6

摘要:

The cell-biological program termed the epithelial-to-mesenchymal transition (EMT) plays an important role in both development and cancer progression. Depending on the contextual signals and intracellular gene circuits of a particular cell, this program can drive fully epithelial cells to enter into a series of phenotypic states arrayed along the epithelial-mesenchymal phenotypic axis. These cell states display distinctive cellular characteristics, including stemness, invasiveness, drug-resistance and the ability to form metastases at distant organs, and thereby contribute to cancer metastasis and relapse. Currently we still lack a coherent overview of the molecular and biochemical mechanisms inducing cells to enter various states along the epithelial-mesenchymal phenotypic spectrum. An improved understanding of the dynamic and plastic nature of the EMT program has the potential to yield novel therapies targeting this cellular program that may aid in the management of high-grade malignancies.

关键词: epithelial-to-mesenchymal transition     cancer     metastasis     cancer stem cell    

Phase transition regulation and caloric effect

《能源前沿(英文)》 2023年 第17卷 第4期   页码 463-477 doi: 10.1007/s11708-023-0860-1

摘要: Solid state refrigeration based on caloric effect is regarded as a potential candidate for replacing vapor-compression refrigeration. Numerous methods have been proposed to optimize the refrigeration properties of caloric materials, of which single field tuning as a relatively simple way has been systemically studied. However, single field tuning with few tunable parameters usually obtains an excellent performance in one specific aspect at the cost of worsening the performance in other aspects, like attaining a large caloric effect with narrowing the transition temperature range and introducing hysteresis. Because of the shortcomings of the caloric effect driven by a single field, multifield tuning on multicaloric materials that have a coupling between different ferro-orders came into view. This review mainly focuses on recent studies that apply this method to improve the cooling performance of materials, consisting of enlarging caloric effects, reducing hysteresis losses, adjusting transition temperatures, and widening transition temperature spans, which indicate that further progress can be made in the application of this method. Furthermore, research on the sign of lattice and spin contributions to the magnetocaloric effect found new phonon evolution mechanisms, calling for more attention on multicaloric effects. Other progress including improving cyclability of FeRh alloys by introducing second phases and realizing a large reversible barocaloric effect by hybridizing carbon chains and inorganic groups is described in brief.

关键词: phase transition regulation     caloric effect     solid state refrigeration    

Studies on the liquid-liquid interfacial mass transfer process using holographic interferometry

ZHAO Chaofan, ZHU Chunying, MA Youguang

《化学科学与工程前沿(英文)》 2008年 第2卷 第1期   页码 1-4 doi: 10.1007/s11705-008-0006-3

摘要: This paper aims at the interfacial phenomena of liquid-liquid mass transfer and its characteristic. By using the real-time holographic technique, the concentration distributions on the aqueous side were obtained according to holographic diagrams of mass transfer of ethanol through the interface of oil and water at different initial concentrations. Furthermore, the concentrations near the interface and the mass transfer coefficients were attained. A correlation of concentration near the interface to the concentration of the solute in the oil side was proposed. An approach of interfacial energy with solute concentration was established, and the calculated results are at good agreement with the experimental data. It is indicated that the liquid-liquid mass transfer process is approximately in accordance with two-film theory, the interfacial performance may be changed by the addition of the solute, and the interface of liquid-liquid is non-equilibrium thermodynamically during the mass transfer process.

关键词: liquid-liquid     different     real-time holographic     addition     transfer    

Interfacial induction and regulation for microscale crystallization process: a critical review

《化学科学与工程前沿(英文)》 2022年 第16卷 第6期   页码 838-853 doi: 10.1007/s11705-021-2129-8

摘要: Microscale crystallization is at the frontier of chemical engineering, material science, and biochemical research and is affected by many factors. The precise regulation and control of microscale crystal processes is still a major challenge. In the heterogeneous induced nucleation process, the chemical and micro/nanostructural characteristics of the interface play a dominant role. Ideal crystal products can be obtained by modifying the interface characteristics, which has been proven to be a promising strategy. This review illustrates the application of interface properties, including chemical characteristics (hydrophobicity and functional groups) and the morphology of micro/nanostructures (rough structure and cavities, pore shape and pore size, surface porosity, channels), in various microscale crystallization controls and process intensification. Finally, possible future research and development directions are outlined to emphasize the importance of interfacial crystallization control and regulation for crystal engineering.

关键词: interfacial crystallization     heterogeneous nucleation     supersaturation     micro/nanostructure     process control and intensification    

Controlling microbiological interfacial behaviors of hydrophobic organic compounds by surfactants in

ZHANG Dong,ZHU Lizhong

《环境科学与工程前沿(英文)》 2014年 第8卷 第3期   页码 305-315 doi: 10.1007/s11783-014-0647-z

摘要: Bioremediation of hydrophobic organic compounds (HOCs) contaminated soils involves several physicochemical and microbiological interfacial processes among the soil-water-microorganism interfaces. The participation of surfactants facilitates the mass transport of HOCs in both the physicochemical and microbiological interfaces by reducing the interfacial tension. The effects and underlying mechanisms of surfactants on the physicochemical desorption of soil-sorbed HOCs have been widely studied. This paper reviewed the progress made in understanding the effects of surfactant on microbiological interfacial transport of HOCs and the underlying mechanisms, which is vital for a better understanding and control of the mass transfer of HOCs in the biodegradation process. In summary, surfactants affect the microbiological interfacial behaviors of HOCs during three consecutive processes: the soil solution-microorganism sorption, the transmembrane process, and the intracellular metabolism. Surfactant could promote cell sorption of HOCs depending on the compatibility of surfactant hydrophile hydrophilic balance (HLB) with cell surface properties; while the dose ratio between surfactant and biologic mass (membrane lipids) determined the transmembrane processes. Although surfactants cannot easily directly affect the intracellular enzymatic metabolism of HOCs due to the steric hindrace, the presence of surfactants can indirectly enhanced the metabolism by increasing the substrate concentrations.

关键词: biodegradation     sorption     transmembrane transport     microbiological interfaces     surfactants    

A state-of-the-art review on interfacial behavior between asphalt binder and mineral aggregate

Meng GUO, Yiqiu TAN, Linbing WANG, Yue HOU

《结构与土木工程前沿(英文)》 2018年 第12卷 第2期   页码 248-259 doi: 10.1007/s11709-017-0422-x

摘要: The interface between asphalt binder and mineral aggregate directly affects the service life of pavement because the defects and stress concentration occur more easily there. The interaction between asphalt binder and mineral aggregate is the main cause of forming the interface. This paper presents an extensive review on the test technologies and analysis methods of interfacial interaction, including molecular dynamics simulation, phase field approach, absorption tests, rheological methods and macro mechanical tests. All of the studies conducted on this topic clearly indicated that the interfacial interaction between asphalt binder and mineral aggregate is a physical-chemical process, and can be qualitatively characterized by microscopical technique (such as SEM and AFM), and also can be quantitatively evaluated by rheological methods and interfacial mechanical tests. Molecular dynamics simulation and phase field approach were also demonstrated to be effective methods to study the interfacial behavior and its mechanism.

关键词: Asphalt binder     Mineral aggregate     Interfacial behavior     Multiscale    

标题 作者 时间 类型 操作

Effects of fiber curvature on the microstructure of the interfacial transition zone in fresh concrete

CHEN Huisu, SUN Wei, ZHAO Qingxin, L. J. Sluys, P. Stroeven

期刊论文

纳米工程混凝土界面过渡区的纳米力学特征

王欣悦, 董素芬, 李镇明, 韩宝国, 欧进萍

期刊论文

The ITZ microstructure, thickness, porosity and its relation with compressive and flexural strength of cement mortar; influence of cement fineness and water/cement ratio

期刊论文

碱激发矿渣混凝土的水化特性及微观结构研究进展

傅强,卜梦鑫, 张兆瑞, 许文瑞, 元强, 牛荻涛

期刊论文

effects of mismatch fracture properties in encapsulation-based self-healing concrete using cohesive-zone

Luthfi Muhammad MAULUDIN, Chahmi OUCIF, Timon RABCZUK

期刊论文

The effects of interfacial strength on fractured microcapsule

Luthfi Muhammad MAULUDIN, Chahmi OUCIF

期刊论文

Applying the multi-zone model in predicting the operating range of HCCI engines

Ming JIA, Maozhao XIE, Zhijun PENG,

期刊论文

Construction of interfacial dynamic bonds for high performance lignin/polymer biocomposites

期刊论文

蛇绿岩型金刚石——探索深部碳循环的新窗口

连东洋, 杨经绥

期刊论文

Epithelial-to-mesenchymal transition in cancer: complexity and opportunities

Yun Zhang, Robert A. Weinberg

期刊论文

Phase transition regulation and caloric effect

期刊论文

Studies on the liquid-liquid interfacial mass transfer process using holographic interferometry

ZHAO Chaofan, ZHU Chunying, MA Youguang

期刊论文

Interfacial induction and regulation for microscale crystallization process: a critical review

期刊论文

Controlling microbiological interfacial behaviors of hydrophobic organic compounds by surfactants in

ZHANG Dong,ZHU Lizhong

期刊论文

A state-of-the-art review on interfacial behavior between asphalt binder and mineral aggregate

Meng GUO, Yiqiu TAN, Linbing WANG, Yue HOU

期刊论文