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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

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Kinetic roughening transition and missing regime transition of melt crystallized polybutene-1 tetragonalphase: growth kinetics analysis

Motoi YAMASHITA

《化学科学与工程前沿（英文）》 2009年第3卷第2期页码 125-134 doi: 10.1007/s11705-009-0001-3

摘要： The morphology and lateral growth rate of polybutene-1 ( -PB1) have been investigated for crystallization from the melt over a wide range of crystallization temperatures from 50 to 110°C. The morphology of -PB1 crystals is a rounded shape at crystallization temperatures lower than 85°C, while lamellar single crystals possess faceted morphology at higher crystallization temperatures. The kinetic roughening transition occurs around 85°C. The nucleation and growth mechanism for crystallization does not work below 85°C, since the growth face is rough. However, the growth rate shows the supercooling dependence derived from the nucleation and growth mechanism. The nucleation theory seems still to work even for rough surface growth. Possible mechanisms for the crystal growth of this polymer are discussed.

关键词： isotactic polybutene-1 tetragonal phase (form Ⅱ) melt crystallization growth rate kinetic roughening morphology

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Experimental study for the stratified to slug flow regime transition mechanism of gas-oil two-phase flow

LIU Yiping, YANG Weilin, WANG Jing

《能源前沿（英文）》 2008年第2卷第2期页码 152-157 doi: 10.1007/s11708-008-0012-7

摘要： Theoretical relations that predict the transition from a stratified pattern to a slug pattern, including a one-dimensional wave model that contains less empiricism than the commonly used Taitel-Dukler model, and the ideal model for stratified flow for the gas-liquid flow in horizontal pipes are presented. Superficial velocities of each phase, as the onset of slugging occurs, were predicted, and theoretical analysis was conducted on the stratified to slug flow regime transition. The friction, existing between the fluid and pipe wall, and on the interface of two phases, was especially taken into account. A theoretical model was applied to an experiment about air-oil two-phase flow in a 50 mm horizontal pipe. The effect of pipe diameter on the transition was also studied. The results show that this approach gives a reasonable prediction over the whole range of flow rates, and better agreement has been achieved between predicted and measured critical parameters.

关键词： two-phase Superficial reasonable prediction one-dimensional gas-liquid

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Lamellar thickness transition of melt-crystallized polybuten-1 tetragonal phase: configurational change

Motoi YAMASHITA

《化学科学与工程前沿（英文）》 2009年第3卷第1期页码 26-32 doi: 10.1007/s11705-009-0002-2

摘要： Lamellar crystal thickness of isotactic polybutene-1 ( -PB1) have been investigated for crystallization in the melt over a wide range of crystallization temperature from 40°C to 90°C by small angle X-ray scattering experiments and density measurements. The crystal thickness demonstrates two linear dependences on inverse supercooling and a transition from one dependence to the other has been observed around = 65°C. Each of the two dependences obeys the nucleation theory in the high and low supercooling ranges, respectively. Chain folding free energy determined from the low supercooling range is larger than that determined from the high supercooling range. Possible mechanisms for the transition are discussed taking account of entropy of chain folding directions.

关键词： isotactic polybutene-1 tetragonal phase crystal thickness melt growth chain folding small angle X-ray scattering nucleation theory end surface free energy

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Factors affecting photocatalytic performance through the evolution of the properties due to the phasetransition from NaBiO·2HO to BiO

《能源前沿（英文）》 2022年第16卷第3期页码 471-482 doi: 10.1007/s11708-021-0778-4

摘要： The phase transition process of a photocatalytic system from NaBiO₃·2H₂O to BiO_2–_x has been investigated to understand the important factors that affect photocatalytic performance in a composite system. It is found that a proper amount of BiO_2–_x on the surface of NaBiO₃·2H₂O could effectively suppress the electron/hole recombination and increase the exposed reactive sites for photocatalytic reaction. A fully covered BiO_2–_x on NaBiO₃·2H₂O results in a dramatical decrease of photocatalytic degradation of dye. An over long hydrothermal process can result in BiO_2–_x with reduced oxygen vacancies, which degrades the photocatalytic activity. Furthermore, the photocatalytic reduction ability of CO₂ conversion has been investigated, indicating that the surface activity to different reactants also directly affects the catalytic performance. The investigation of the gradient phase transition process presents a clear guidance to construct a desired photocatalytic system, in addition to selecting gradient materials with suitable bandgap structure and a morphology with different fraction and distribution of each component. The defect evolution of each component during construction of a composite is also an important factor that should be optimized and considered in making a composite to achieve high photocatalytic efficiency.

关键词： composite construction distribution BiO_2–_x evolution of defects

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凝变除湿复合烟气深度净化技术工程应用 Article

刘建民, 朱法华, 马修元

《工程（英文）》 2018年第4卷第3期页码 416-420 doi: 10.1016/j.eng.2018.05.009

摘要：

湿法脱硫后湿烟气排放会形成湿烟羽现象，不仅浪费水资源，产生视觉污染，同时湿烟气中的SO3、溶解在液态水中的盐、颗粒物等在大气环境中会形成二次污染。本文提出了一种凝变除湿复合烟气深度净化技术，包括凝变湿电一体化和凝变除雾一体化两种技术路线，分别在630 MW和1000 MW燃煤机组上进行了工程应用。结果表明，凝变除湿复合烟气深度净化技术对脱硫后饱和湿烟气的除水量大于4 g·kg-1·℃-1，在烟气温度降低1.5~5.3℃时，可回收烟气中5%~20%的水分，有效节约水资源；显著减少水汽排放，有效消除湿烟羽现象；离子浓度降低65%以上，SO3脱除率大于75%，颗粒物脱除率为92.53%。

关键词：湿烟羽凝变除湿溶解盐 SO3 颗粒物

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Anticorrosive composite self-healing coating enabled by solar irradiation

《化学科学与工程前沿（英文）》 2022年第16卷第9期页码 1355-1366 doi: 10.1007/s11705-022-2147-1

摘要： Self-healing coatings for long-term corrosion protection have received much interest in recent years. However, most self-healing coatings rely on healants released from microcapsules, dynamic bonds, shape memory, or thermoplastic materials, which generally suffer from limited healing times or harsh conditions for self-healing, such as high temperature and UV radiation. Herein, we present a composite coating with a self-healing function under easily accessible sunlight by adding Fe₃O₄ nanoparticles and tetradecanol into epoxy resin. Tetradecanol, with its moderate melting point, and Fe₃O₄ nanoparticles serve as a phase-change component and photothermal material in an epoxy coating system, respectively. Fe₃O₄ nanoparticles endow this composite self-healing coating with good photothermal properties and a rapid thermal response time under simulated solar irradiation as well as outdoor real sunlight. Tetradecanol can flow to and fill defects by phase transition at low temperatures. Therefore, artificial defects created in this type of self-healing coating can be healed by the liquified tetradecanol induced by the photothermal effect of Fe₃O₄ nanoparticles under simulated solar irradiation. The healed coating can still serve as a good barrier for the protection of the underlying carbon steel. These excellent properties make this self-healing coating an excellent candidate for various engineering applications.

关键词： self-healing coating phase transition photothermal effect corrosion protection

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Mesoscopic properties of dense granular materials: An overview

Qicheng SUN, Feng JIN, Guohua ZHANG

《结构与土木工程前沿（英文）》 2013年第7卷第1期页码 1-12 doi: 10.1007/s11709-013-0184-z

摘要： A granular material is a conglomeration of discrete solid particles. It is intrinsically athermal because its dynamics always occur far from equilibrium. In highly excited gaseous states, it can safely be assumed that only binary interactions occur and a number of kinetic theories have been successfully applied. However, for granular flows and solid-like states, the theory is still poorly understood because of the internally correlated structures, such as particle clusters and force networks. The current theory is that the mesoscale characteristics define the key differences between granular materials and homogeneous solid materials. Widespread interest in granular materials has arisen among physicists, and significant progress has been made, especially in understanding the jamming phase diagram and the characteristics of the jammed phase. In this paper, the underlying physics of the mesoscale structure is discussed in detail. A multiscale framework is then proposed for dense granular materials.

关键词： granular matter macroscopic structure jamming phase transition

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十字型出口人员疏散的堵塞研究

陈涛,宋卫国,范维澄,陆守香

《中国工程科学》 2004年第6卷第4期页码 56-60

摘要：

在开放边界条件下，采用无后退有偏随机走动者格子气模型对十字路口的行人疏散动力学进行了计算和模拟。结果显示，当纬向边界行人密度保持恒定时，经向和纬向通道行人堵塞现象的出现取决于不同的经向边界行人密度；当纬向通道宽度保持不变时，发生堵塞的临界边界行人密度取决于不同的经向通道宽度，纬向和经向的行人堵塞动力学演变具有不同的特征。模拟结果对于疏散通道的设计具有指导意义。

关键词：人员疏散格子气模型堵塞相变火灾

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PNIPAM core-shell particles and hollow spheres by using hydrophobic interaction and thermosensitive phase

ZHU Dongmei, WANG Fei, GAO Cuiling, XU Zheng

《化学科学与工程前沿（英文）》 2008年第2卷第3期页码 253-256 doi: 10.1007/s11705-008-0049-5

摘要： This paper reports an easy and effective way to fabricate polystyrene/poly (-isopropylacrylamide) (PS/PNIPAM) core-shell particles and PNIPAM hollow spheres. The main point of the method is to take advantage of the hydrophobic interaction between initiator and PS particles. The hydrophobic azodiisobutyronitriles automatically concentrate around the PS particles and initiate polymerization of -isopropylacrylamide (NIPAM) and the crosslinker methylene bisacrylamide (MBA), which dissolve in the aqueous phase, at the surface of the PS nanoparticles. Then, PNIPAM adheres to the PS particles to form a core-shell structure as a result of their hydrophobic interaction. This interaction is due to the unique property of PNIPAM, namely, its ability to transition from hydrophilic to hydrophobic when the temperature rises to 32°C. Furthermore, the hollow PNIPAM spheres were obtained by etching the PS core with chloroform.

关键词： initiator core-shell transition polystyrene/poly advantage

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新型苯加氢反应器的研究

A.M.Anter,程振民,肖琼,胡劲松,袁渭康

《中国工程科学》 2000年第2卷第6期页码 59-63

摘要：

文章提出了依靠相变蒸发吸收反应热，同时解决移热和加速反应等问题的新型化学反应器并开展了实验研究。实验在加压下进行，催化剂床层高度为1.0m，反应器内径为0.02m，苯加氢生成环已烷为研究体系，实验中采用气液并流向上流动的方式通过催化剂床层。在操作条件：ρ=0.5～3.0MPa、θ=150℃、液体空速=1.1~6.9h^-1、氢油体积比=300~1910下，苯的转化率及环已烷的收率均可达到99.9%以上。为了防止反应器内发生飞温，实验采用苯与环已烷的混合物作为原料，其中苯的质量分数为15%~25%。随着反应物料不断进入反应器，液相物料吸收反应放出的热量而蒸发，因此在适当的操作条件下床层内可同时存在液相反应区、气液两相区和气相反应区。

关键词：相变反应器苯加氢环已烷

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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

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Energy transition management towards a low-carbon world

《工程管理前沿（英文）》 2022年第9卷第3期页码 499-503 doi: 10.1007/s42524-022-0201-9

关键词： energy transition low-carbon technology system modeling transition path emission reduction

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Smart oilfield development and transition of petroleum-based cities

He LIU, Xinhua MA

《工程管理前沿（英文）》 2019年第6卷第2期页码 299-301 doi: 10.1007/s42524-019-0024-5

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Energy transition toward carbon-neutrality in China: Pathways, implications and uncertainties

《工程管理前沿（英文）》 2023年第10卷第2期页码 358-372 doi: 10.1007/s42524-022-0202-8

摘要： Achieving carbon neutrality in China before 2060 requires a radical energy transition. To identify the possible transition pathways of China’s energy system, this study presents a scenario-based assessment using the Low Emissions Analysis Platform (LEAP) model. China could peak the carbon dioxide (CO₂) emissions before 2030 with current policies, while carbon neutrality entails a reduction of 7.8 Gt CO₂ in emissions in 2060 and requires an energy system overhaul. The assessment of the relationship between the energy transition and energy return on investment (EROI) reveals that energy transition may decrease the EROI, which would trigger increased energy investment, energy demand, and emissions. Uncertainty analysis further shows that the slow renewable energy integration policies and carbon capture and storage (CCS) penetration pace could hinder the emission mitigation, and the possible fossil fuel shortage calls for a much rapid proliferation of wind and solar power. Results suggest a continuation of the current preferential policies for renewables and further research and development on deployment of CCS. The results also indicate the need for backup capacities to enhance the energy security during the transition.

关键词： carbon neutrality energy transition uncertainty EROI LEAP