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Numerical study and control method of interaction of nucleation and boundary layer separation in condensingflow

Liansuo AN , Zhi WANG , Zhonghe HAN ,

《能源前沿（英文）》 2009年第3卷第3期页码 254-261 doi: 10.1007/s11708-009-0047-4

摘要： The spontaneous nucleation flow in turbine cascade was numerically studied. The model was implemented within a full Navier–Stokes viscous flow solution procedure and the process of condensation was calculated by the quadrature method of moments that shows good accuracy with very broad size distributions. Results were presented for viscous and inviscous flow, showing the influence of boundary layer separation and wake vortices on spontaneous nucleation. The results show that the degree of flow separation in wet steam flow is greater than that in superheated steam flow due to condensation shock and that the loss cannot be neglected. Furthermore, the impact of boundary layer separation and wake vortices on velocity profiles and its implications for profile loss were considered. The calculations showed that layer separation and wake vortices influence nucleation rate, leading to different droplet distributions. A method for controlling homogeneous nucleation and for reducing degree of flow separation in high-speed transonic wet steam flow was presented. The liquid phase parameter distribution is sensitive to the suction side profile of turbine cascade, which impacts the nucleation rate distribution leading to different droplet distributions and affects the degree of flow separation. The numerical study provides a practical design method for turbine blade to reduce wetness losses.

关键词： wet steam two-phase flow spontaneous condensation numerical simulation flow separation profile loss

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Analysis of flow over backward facing step with transition

Dwarikanath RATHA,Arindam SARKAR

《结构与土木工程前沿（英文）》 2015年第9卷第1期页码 71-81 doi: 10.1007/s11709-014-0270-x

摘要： The present study deals with the study of the velocity distribution and the separation phenomenon of flow of air over a two dimensional backward facing step. The flow of air over a backward facing step has been investigated numerically using FLUENT. Flow simulation has been carried out in a backward facing step having an expansion ratio (ratio of the height before and after the step) of 1:1.94 and the results obtained are compared with the published experimental results. Comparison of flow characteristics between steps with three different transitions is made. The variation of reattachment length for all the three cases are analyzed for wide range of Reynolds number ranging from 100 to 7000 which covers the laminar, transition and turbulent flow of air. Simulation of the flow over steps with expansion ratios of 1:1.24, 1:1.38, 1:1.47, 1:1.53, 1:1.94, 1:2.20 are also carried out to examine the effect of different expansion ratios on the reattachment length. It is found that the primary reattachment length increases with increase in the expansion ratio. The primary reattachment length at the bottom wall downstream of the step is minimum for the step with round edged transition and maximum for the step with a vertical drop transition.

关键词： Reattachment length backward facing step transition flow separation k-? model

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Experimental study on flow behavior at open channel confluences

WANG Xiekang, WANG Xianye, LU Weizhen, LIU Tonghuan

《结构与土木工程前沿（英文）》 2007年第1卷第2期页码 211-216 doi: 10.1007/s11709-007-0025-z

摘要： Channel confluences are common in natural rivers and hydraulic engineering, and the flow behavior at confluences becomes very complex because of the interaction between the tributary and the main river. In this study, the experiments were performed in a combined flume with a 30º angle between the main and tributary flume located at Sichuan University. The velocity was measured by using a three-component acoustic Doppler velocimeter (ADV) over a grid defined throughout the junction region. Based on the analysis of the velocity at the confluence, the distinctive characteristics of a channel confluence flow may be divided into several zones including a zone of separation immediately downstream of the junction branch channel, the maximum and minimum velocity regions at the upstream and downstream in the confluent channel, and a shear plane developed between the two combining flows downstream of the confluent channel. In addition, secondary circulations in different directions at the higher and lower velocity zones are observed as well.

关键词： ADV different interaction separation downstream

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瑞德西韦核碱基单元的连续流合成 Article

郭永兴, 刘敏杰, 姜梅芬, 陶媛, 程荡, 陈芬儿

《工程（英文）》 2023年第21卷第2期页码 92-100 doi: 10.1016/j.eng.2021.07.029

摘要：

本研究通过五步连续流合成了抗病毒药物瑞德西韦的核碱基单元7-溴吡咯[2,1-f][1‒2,4]三嗪-4-胺。采用间歇式合成化学方法，利用广泛可用且廉价的起始原料吡咯，通过顺序流动操作成功生产了7-溴吡咯[2,1-f][1‒2,4]三嗪-4-胺。在最佳流动条件下，7-溴吡咯[2,1-f][1‒2,4]三嗪-4-胺的分离收率为14.1%，总停留时间为79 min，通量为2.96 g∙h⁻¹,总停留时间明显短于批处理程序中消耗的总时间（大于26.5 h）。在流动中，有利地促进了涉及危险和不稳定的中间体的高度放热的Vilsmeier-Haack 和N-胺化反应、氧化液-液双相转化及需要严格低温条件的溴化反应。这种合成方法的显著特点是，通过部署专用设备和分离单元，将后处理程序完全集成到反应序列中，从而形成一个精简的连续流系统，最大限度地提高整个过程的效率。该方法是一种更环保、更可持续的高效、安全地制备核碱基单元的方法。

关键词：流动化学连续多步合成微反应技术反应分离集成

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Experimental investigation on oil-gas separator of air-conditioning systems

Dianbo XIN,Shuliang HUANG,Song YIN,Yuping DENG,Wenqiang ZHANG

《能源前沿（英文）》 2019年第13卷第2期页码 411-416 doi: 10.1007/s11708-017-0447-9

摘要： The oil-return system plays an important role in the variable refrigerant flow (VRF) systems because it ensures the reliable operation of the VRF systems. The oil-gas separator is the most essential component of the oil-return system, and the separation efficiency of the separator directly influences the performance of the VRF systems. Therefore, in this paper, a test rig was built to measure the oil discharge ratio of the compressor and the separation efficiency of the oil-gas separator. A sound velocity transducer was used to measure the oil mass concentration instantaneously, because the sound velocity was changed with the mass ratio of oil to refrigerant. The separation efficiency of the separator could be obtained by comparing the mass fraction of oil to refrigerant before and after the separator was connected to the system.

关键词： variable refrigerant flow system oil-gas separator separation efficiency

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Phase separation in cGAS-STING signaling

《医学前沿（英文）》页码 855-866 doi: 10.1007/s11684-023-1026-6

摘要： Biomolecular condensates formed by phase separation are widespread and play critical roles in many physiological and pathological processes. cGAS-STING signaling functions to detect aberrant DNA signals to initiate anti-infection defense and antitumor immunity. At the same time, cGAS-STING signaling must be carefully regulated to maintain immune homeostasis. Interestingly, exciting recent studies have reported that biomolecular phase separation exists and plays important roles in different steps of cGAS-STING signaling, including cGAS condensates, STING condensates, and IRF3 condensates. In addition, several intracellular and extracellular factors have been proposed to modulate the condensates in cGAS-STING signaling. These studies reveal novel activation and regulation mechanisms of cGAS-STING signaling and provide new opportunities for drug discovery. Here, we summarize recent advances in the phase separation of cGAS-STING signaling and the development of potential drugs targeting these innate immune condensates.

关键词： biomolecular condensates phase separation cGAS-STING pathway cGAS STING cGAMP interferon

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Selective capture and separation of xenon and krypton using metal organic frameworks: a review

《化学科学与工程前沿（英文）》 2023年第17卷第12期页码 1895-1912 doi: 10.1007/s11705-023-2355-3

摘要： Xenon and krypton are widespread useful noble gases in commercial lighting, lasers, electronics, and medical industry. At the same time, radioactive noble gases may proliferate from used nuclear fuel and diffuse in open atmospheres. Metal organic frameworks as hotspot porous materials for gases uptake and separation are considered to be potential solutions. In this review, we comprehensively summarized recent researches on metal organic frameworks for selective capture and separation of xenon and krypton. Particularly, we followed the aspects of different optimal design strategies, including optimal pore/cage size and geometry, open metal sites, ions (anions and cations), and polar functional groups for enhancing the xenon adsorption and separation performances. Meanwhile, a comparison of each strategy and the mechanisms of xenon/krypton separation were pointed out. The separation of krypton from gases mixtures by dual-bed systems was further discussed. Finally, some existing challenges and opportunities for possible real applications were proclaimed.

关键词： metal organic frameworks xenon krypton selective separation used nuclear fuel

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大鼠骨髓间质干细胞的分离纯化与鉴定

张荣利,冯　雪,张会亮,罗国安,李连达,王义明

《中国工程科学》 2007年第9卷第7期页码 89-94

摘要：

采用密度梯度离心法分离骨髓间质干细胞，差速贴壁法进行纯化，应用流式细胞仪、激光共聚焦显微镜等对纯化细胞进行鉴定，结果细胞表面抗原CD29，CD44，CD105，CD166表达呈阳性，而CD14，CD34，CD45表达呈阴性。采用RT唱PCR鉴定了三个基因：nestin，NST，Oct-４，前两者呈阳性表达，后者弱阳性表达。这些细胞特异抗原与基因表达综合起来，表明得到的细胞具备骨髓间质干细胞的特性。密度梯度分离与差速贴壁相结合，可获得较好均一性的骨髓间质干细胞，是一种简单可靠、易于推广的骨髓干细胞获取方法，可为细胞与组织工程研究提供种子细胞。

关键词：大鼠骨髓间质干细胞流式细胞分析

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Highly hydrophobic oil−water separation membrane: reutilization of waste reverse osmosis membrane

《化学科学与工程前沿（英文）》 2023年第17卷第10期页码 1606-1615 doi: 10.1007/s11705-022-2200-0

摘要： The increasing applications of seawater desalination technology have led to the wide usage of polyamide reverse osmosis membranes, resulting in a large number of wasted reverse osmosis membranes. In this work, the base nonwoven layer of the wasted reverse osmosis membrane was successfully modified into the hydrophobic membrane via surface deposition strategy including TiO₂ and 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS), respectively. Various techniques were applied to characterize the obtained membranes, which were then used to separate the oil–water system. The optimally modified membrane displayed good hydrophobicity with a contact angle of 135.2° ± 0.3°, and its oil–water separation performance was as high as 97.8%. After 20 recycle tests, the oil–water separation performance remained more than 96%, which was attributed to the film adhesion of the anchored TiO₂ and PFOTS layer on the surface. This work might provide a new avenue for recycling the wasted reverse osmosis membrane used in oily wastewater purification.

关键词： oil–water separation wasted reverse osmosis membrane hydrophobic modification

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Phase separation time/temperature dependence of thermoplastics-modified thermosetting systems

ZHANG Xiujuan, XU Yuanze, YI Xiaosu

《化学科学与工程前沿（英文）》 2008年第2卷第3期页码 276-285 doi: 10.1007/s11705-008-0057-5

摘要： The cure-induced phase separation processes of various thermoplastics(TP)-modified thermosetting systems which show upper critical solution temperature (UCST) or lower critical solution temperature (LCST) were studied with emphasis on the temperature dependency of the phase separation time and its potential application in the cure time-temperature processing window. We found that the phase separation time/temperature relationship follows the simple Arrhenius equation. The cure-induced phase separation activation energy (ps) generated from the linear fitting of the Arrhenius equation is irrelevant to the detection means of phase separation time. We also found that (ps) is insensitive to TP content, TP molecular weight and curing rate, but it changes with the cure reaction kinetics and the chemical environment of the systems. With the established phase separation time-temperature dependence relation, we can easily establish the whole cure time-temperature transformation (TTT) diagram with morphology information which is a useful map for the TP/TS composites processing industry.

关键词： separation time-temperature temperature dependency cure-induced separation activation temperature

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Microfluidic production of liposomes through liquid–liquid phase separation in ternary droplets

《化学科学与工程前沿（英文）》 2022年第16卷第6期页码 1017-1022 doi: 10.1007/s11705-021-2118-y

摘要： Liposomes, the self-assembled phospholipid vesicles, have been extensively used in various fields such as artificial cells, drug delivery systems, biosensors and cosmetics. However, current microfluidic routes to liposomes mostly rely on water-in-oil-in-water double emulsion droplets as templates, and require complex fabrication of microfluidic devices, and tedious manipulation of multiphase fluids. Here we present a simple microfluidic approach to preparing monodisperse liposomes from oil-in-water droplets. For demonstration, we used butyl acetate-water-ethanol ternary mixtures as inner phase and an aqueous solution of surfactants as outer phase to make oil-in-water droplets, which can evolve into water-in-oil-in-water double emulsion droplets by liquid–liquid phase separation of ternary mixtures. Subsequently, the resultant water-in-oil-in-water droplets underwent a dewetting transition to form separated monodisperse liposomes and residual oil droplets, with the assistance of surfactants. The method is simple, does not require complex microfluidic devices and tedious manipulation, and provides a new platform for controllable preparation of liposomes.

关键词： microfluidics liposomes ternary droplets phase separation

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Imprinted membranes for sustainable separation processes

Laura Donato, Enrico Drioli

《化学科学与工程前沿（英文）》 2021年第15卷第4期页码 775-792 doi: 10.1007/s11705-020-1991-0

摘要： The rapid industrial growth and the necessity of recovering and recycling raw materials increased the interest in the production of highly selective and efficient separation tools. In this perspective, a relevant input was given by the membrane-based technology and the production of imprinted membranes, which possess specific recognition properties at molecular and ionic level, offers the possibility of developing sustainable and green processes. Furthermore, the integration of imprinted membranes with traditional or membrane-based approaches is a promising strategy in the logic of process intensification, which means the combination of different operations in a single apparatus. This work discusses the concept and separation mechanisms of imprinted membranes. Furthermore, it presents an overview of their application in organic solvent nanofiltration, for the removal of toxic agents and recovery solvent, as well as valuable compounds. The recent advances in water treatment, such as pesticide removal and recovery of metal ions, are also discussed. Finally, potential applications of imprinted membranes in hybrid processes are highlighted, and a look into the future of membrane separations for water treatment and recovery of critical raw materials is offered.

关键词： sustainable processes membrane separation molecular recognition imprinted membranes water treatment

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Fabrication of a superhydrophilic/underwater superoleophobic stainless steel mesh for oil/water separation

《化学科学与工程前沿（英文）》 2023年第17卷第1期页码 46-55 doi: 10.1007/s11705-022-2170-2

摘要： Because of the increasing amount of oily wastewater produced each day, it is important to develop superhydrophilic/underwater superoleophobic oil/water separation membranes with ultrahigh flux and high separation efficiency. In this paper, a superhydrophilic/underwater superoleophobic N-isopropylacrylamide-coated stainless steel mesh was prepared through a simple and convenient graft polymerization approach. The obtained mesh was able to separate oil/water mixtures only by gravity. In addition, the mesh showed high-efficiency separation ability (99.2%) and ultrahigh flux (235239 L∙m^–2∙h^–1). Importantly, due to the complex cross-linked bilayer structure, the prepared mesh exhibited good recycling performance and chemical stability in highly saline, alkaline and acidic environments.

关键词： oil/water separation N-isopropylacrylamide stainless steel mesh ultrahigh flux

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Easily-manufactured paper-based materials with high porosity for adsorption/separation applications in

《化学科学与工程前沿（英文）》 2023年第17卷第7期页码 830-839 doi: 10.1007/s11705-022-2267-7

摘要： A multi-functional porous paper-based material was prepared from grass pulp by simple pore-forming and green cross-linking method. As a pore-forming agent, calcium citrate increased the porosity of the paper-based material from 30% to 69% while retaining the mechanical strength. The covalent cross-linking of citric acid between cellulose fibers improved both the wet strength and adsorption capacity. In addition, owing to the introduction of high-content carboxyl groups as well as the construction of hierarchical micro-nano structure, the underwater oil contact angle was up to 165°. The separation efficiency of the emulsified oil was 99.3%, and the water flux was up to 2020 L·m^–2·h^–1. The theoretical maximum adsorption capacities of cadmium ion, lead ion and methylene blue reached 136, 229 and 128.9 mg·g^–1, respectively. The continuous purification of complex wastewater can be achieved by using paper-based materials combined with filtration technology. This work provides a simple, low cost and environmental approach for the treatment of complex wastewater containing insoluble oil, organic dyes, and heavy metal ions.

关键词： adsorption oil–water separation underwater superoleophobicity wastewater treatment

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Biodegradable, superhydrophobic walnut wood membrane for the separation of oil/water mixtures

《化学科学与工程前沿（英文）》 2022年第16卷第9期页码 1377-1386 doi: 10.1007/s11705-022-2157-z

摘要： The preparation of environmentally friendly oil/water separation materials remains a great challenge. Freeze-drying of wood after lignin removal yields wood aerogels, which can be used as substrates to prepare fluorine-free environmentally friendly superhydrophobic materials, However, they are more suitable for absorption rather than filtration applications due to their poor strength. A study using cross-sections of pristine wood chips as substrates retains the original strength of wood, but the use of the cross-sectional of wood pieces limits their thickness, strength, and size. In this paper, a degradable fluorine-free superhydrophobic film (max. water contact angle of approximately 164.2°) with self-cleaning and abrasion resistance characteristics was prepared by a one-step method using pristine and activated walnut longitudinal section films as the substrate, with tetraethyl orthosilicate as a precursor and dodecyltriethoxysilane as a modifier. The tensile strength results show that superhydrophobic films with pristine or activated wood substrates maintained the strength of pristine wood and were 2.2 times stronger than the wood aerogel substrate. In addition, after cross-laminating the two samples, the films had the ability to separate oil and water by continuous filtration with high efficiency (98.5%) and flux (approximately 1.3 × 10³ L∙m^‒2∙h^‒1). The method has potential for the large-scale fabrication of degradable superhydrophobic filtration separation membranes.

关键词： wood nanotechnology superhydrophobic biodegradable surface modification oil/water separation