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Customizable Ligand Exchange for Tailored Surface Property of Noble Metal Nanocrystals

Research 2020年第1期2020卷 292-303页

作者： Qikui Fan Hao Yang Juan Ge Shumeng Zhang Zhaojun Liu Bo Lei Tao Cheng Youyong Li Yadong Yin Chuanbo Gao Frontier Institute of Science and Technology State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’anShaanxi 710054China Institute of Functional Nano&Soft Materials(FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials&DevicesJoint International Research Laboratory of Carbon-Based Functional Materials and DevicesSoochow UniversitySuzhouJiangsu 215123China Department of Chemistry University of CaliforniaRiversideCalifornia 92521USA

It is highly desirable,while still challenging,to obtain noble metal nanocrystals with custom capping ligands,because their colloidal synthesis relies on specific capping ligands for the shape control while conventional ligand exchange processes suffer from“the strong replaces the weak”limitation,which greatly hinders their ***,we report a general and effective ligand exchange approach that can replace the native capping ligands of noble metal nanocrystals with virtually any type of ligands,producing flexibly tailored surface *** key is to use diethylamine with conveniently switchable binding affinity to the metal surface as an intermediate *** a strong ligand,it in its original form can effectively remove the native ligands;while protonated,it loses its binding affinity and facilitates the adsorption of new ligands,especially weak ones,onto the metal *** this means,the irreversible order in the conventional ligand exchange processes could be *** efficacy of the strategy is demonstrated by mutual exchange of the capping ligands among cetyltrimethylammonium,citrate,polyvinylpyrrolidone,and *** novel strategy significantly expands our ability to manipulate the surface property of noble metal nanocrystals and extends their applicability to a wide range of fields,particularly biomedical applications.

关键词： properties replace mutual

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Effect of Inorganic Nanoparticles on Energy-Storage Properties of P(VDF-HFP)-Based Nanocomposites

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ADVANCED engineering MATERIALS 2023年第14期25卷 2300070-2300070页

作者： Guo, Yan Zhou, Di Li, Da Zhao, Weichen Pang, LiXia Shi, Zhongqi Liu, Wenfeng Su, Jinzhan Zhou, Tao Sun, Shikuan Xi An Jiao Tong Univ Sch Elect Sci & Engn Elect Mat Res Lab Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Sch Elect Sci & Engn Key Lab Multifunct Mat & StructMinist Educ Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Int Ctr Dielect Res Sch Elect Sci & Engn Xian 710049 Shaanxi Peoples R China Xian Technol Univ Microoptoelectron Syst Labs Xian 710032 Shaanxi Peoples R China Xi An Jiao Tong Univ State Key Lab Mech Behav Mat Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Elect Insulat & Power Equipment Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Int Res Ctr Renewable Energy State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Hangzhou Dianzi Univ Sch Elect & Informat Engn Hangzhou 310018 Peoples R China Foshan Univ Sch Mat Sci & Energy Engn Foshan 528000 Guangdong Peoples R China

Polyvinylidene fluoride (PVDF) and its copolymers have been widely used in polymer-based film capacitors due to their relatively high permittivity and electrical displacement compared with other polymers. Herein, poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) is selected as the polymer matrix, and 0.5 (Bi0.5Na0.5)TiO3-0.5(Sr0.85Sm0.1)TiO3 (BNT-SST) nanoparticles are added as the filler into the polymer to prepare BNT-SST/P(VDF-HFP) nanocomposites. The microstructure, electrical properties, mechanical properties, and energy-storage properties of the nanocomposites are investigated. The addition of BNT-SST nanoparticles improves the dielectric characteristics and breakdown strength of the nanocomposites. Particularly, when the BNT-SST filler content is 0.7 vol%, the highest breakdown strength reaches 545 MV m(-1), which is 1.3 times higher than pure P(VDF-HFP). In addition, the insulation and mechanical properties of BNT-SST/P(VDF-HFP) composite films are improved. The highest direct current resistivity and Young's modulus obtained by 0.7 vol% BNT-SST/P(VDF-HFP) nanocomposites are 6.8 x 10(13) omega cm and 1.94 GPa, respectively. More importantly, at 545 MV m(-1), the energy-storage density and efficiency of 0.7 vol% BNT-SST/P(VDF-HFP) composites are 19.07 J cm(-2) and 67.01%, respectively, which are better than other polymer matrix composites. These findings suggest that the addition of inorganic nanoparticles has important research implications for improving the energy-storage performance of polymer-based film capacitors.

关键词： BNT-SST P(VDF-HFP) nanocomposites breakdown strength efficiency energy-storage density

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Efficient super-resolution of pipeline transient process modeling using the Fourier Neural Operator

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ENERGY 2024年 302卷

作者： Gong, Junhua Shi, Guoyun Wang, Shaobo Wang, Peng Chen, Bin Chen, Yujie Wang, Bohong Yu, Bo Jiang, Weixin Li, Zongze Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Kunlun Digital Intelligence Technol Co Beijing 102266 Peoples R China PipeChina Oil & Gas Control Ctr Dongtucheng Rd Beijing 100013 Peoples R China Beijing Inst Petrochem Technol Sch Mech Engn Beijing 102617 Peoples R China Zhejiang Ocean Univ Natl & Local Joint Engn Res Ctr Harbor Oil & Gas Storage & Transportat Technol Zhoushan 316022 Peoples R China Beijing Univ Technol Fac Environm & Life Beijing 100124 Peoples R China

The rapid simulation of pipelines significantly facilitates tasks such as pipeline operation scheduling and optimization, while neural networks can offer an efficient alternative modeling approach. Based on the Fourier Neural Operator (FNO), this study proposes a rapid and comprehensive model for computing the transient natural gas pipeline processes. To further enhance the performance of the model, a novel loss function is proposed that integrates the Benedict-Webb-Rubin-Starling (BWRS) equation as a physical constraint. After being trained on finite-dimensional data, the proposed model demonstrates high accuracy, good grid invariance, and significant computational acceleration. Compared with data from existing studies and simulation results of the renowned natural gas pipeline simulation software TGNET, the relative error of the proposed model remains below 2.5 %. The trained model can also predict outcomes beyond the original training data with a root mean squared error value of 2.542 x 10 -3 , demonstrating good grid invariance. Moreover, compared to the traditional numerical algorithm, the model exhibits a significantly high acceleration ratio, typically achieving an order of magnitude of 10 2 and occasionally up to 10 3 . In conclusion, the proposed model can serve as a solver for transient natural gas pipeline simulation processes, efficiently providing accurate simulation results.

关键词： Natural gas pipeline Fourier neural operator Neural network Dynamic simulation Partial differential equations

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Effects of Integral Scale on Darrieus-Landau Instability in Turbulent Premixed Flames

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flow TURBULENCE AND COMBUSTION 2019年第1期103卷 225-246页

作者： Zhang, Weijie Wang, Jinhua Guo, Shilong Yu, Qianqian Jin, Wu Zhang, Meng Huang, Zuohua Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Nanjing Univ Aeronaut & Astronaut Coll Energy & Power Engn Nanjing 210016 Jiangsu Peoples R China

Previous studies have revealed the existence of distinct regimes of DL-stable and unstable turbulent flames, depending on whether the DL instability could be minimized or not. The mechanism of how mixture composition, flame macroscale and turbulence intensity, etc. act on DL instability has been extensively studied. Even though, the role played by turbulent length scale on DL instability is still unclear. The present study has been experimentally focused on the effect of turbulent integral scale on DL instability of premixed turbulent Bunsen flames. Flame fronts of C3H8/air mixture (phi=0.8) under different turbulence conditions are captured by OH-PLIF technique. It is observed that the DL-unstable flames, obtained at relatively large integral scale and with cusps observed on the flame fronts, transform to be DL-stable flames with planar or disorderly wrinkled flame fronts as the integral scale decreases, indicating the indispensable role of integral scale on DL instability. These cusps on DL-unstable flame fronts decrease flame surface density while enlarge flame volume. Turbulent burning velocities of DL-unstable flames are augmented compared to DL-stable flames, leading to a similar dual-propagation model as observed in literatures. The threshold where turbulence shadows DL instability is analyzed by upgrading a previous model of [Phys. Rev. E 84 (2011) 026322]. The modified model is more reliable to demonstrate the DL-stable and unstable regimes in the Peters-Borghi's diagram.

关键词： Turbulent premixed flames Bunsen flames Darrieus-Landau instability Integral scale Turbulent flame diagram

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Numerical investigation on thermohydraulic performance of high temperature hydrogen in twisted rod channels

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ANNALS OF NUCLEAR ENERGY 2021年 161卷 108434-108434页

作者： Fang, Yuliang Qin, Hao Wang, Chenglong Zhou, Lei Zhang, Jing Zhang, Dalin Tian, Wenxi Su, Guanghui Qiu, Suizheng Xi An Jiao Tong Univ Dept Nucl Sci & Technol Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Shaanxi Key Lab Adv Nucl Energy & Technol Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

Nuclear thermal propulsion (NTP) is one of the most promising approaches for deep space exploration and manned interstellar voyage. As the propellant and coolant of NTP reactors, hydrogen provides higher specific impulse. In this paper, the thermohydraulic performance of high temperature hydrogen flowing through the twisted rod bundles were investigated numerically by contrasting with the cruciform rod bundles and the circular rod bundles. The heat transfer models were validated by literature data and the relative errors are within 20%. Twisted rods could enhance lateral mixing and heat transfer since the twisted lobes and valleys could enhance radial heat transfer and produce a strong rotational flow near the walls disturbing boundary layer, which reduces hot spot factors and assures the thermal safety. The largest relative difference of the J(F) factor between the twisted and other non-twisted channels are 28.0% and 6.1% respectively in this model. (C) 2021 Published by Elsevier Ltd.

关键词： Nuclear thermal propulsion Heat transfer performance flow characteristics Hydrogen Twisted rod channels

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Experimental and Numerical Study on Autoignition Characteristics of the Polyoxymethylene Dimethyl Ether/Diesel Blends

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ENERGY & FUELS 2019年第3期33卷 2538-2546页

作者： Meng, Xin Hu, Erjiang Yoo, Kwang Hee Boehman, Andre L. Huang, Zuohua Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Univ Michigan Dept Mech Engn Ann Arbor MI 48109 USA

A modified cooperative fuel research (CFR) octane rating engine and a constant-volume combustion chamber (CVCC) (CID510) were adopted to investigate the effect of the addition of polyoxymethylene dimethyl ether (PODE) on the ignition characteristics of diesel fuels. PODE was blended in diesel fuel with a volume fraction from 0 to 30%. The ignition delay times of PODE/diesel blends were obtained on a CVCC at a temperature of 833-893 K, and a reduction of environmental oxygen (O-2) content ranges from 21 to 12.8%. With PODE addition, the ignition delay time decreases, whereas the onset of low-temperature heat release (LTHR) moves forward and the peak of LTHR increases. The blends with a higher PODE fraction can weaken the negative effect on ignition delay caused by the reduction of oxygen content in air. The critical compression ratio (CCR) and the apparent heat release rate of binary blends were measured on the CFR engine at an equivalence ratio of 0.5 under homogeneous charge compression ignition combustion mode. The CCR becomes lower with higher PODE content in the blend. All blends exhibited two-stage ignition. The blends with a higher PODE fraction give a higher percentage of LTHR Numerical simulation reveals that decomposition of PODE produces more CH2O, which accelerates the low-temperature reaction. The reactions related to O-center dot and O-2 are enhanced by oxygen available in PODE, which, along with the molecular structure of PODE, results in higher reactivity for the PODE/diesel binary blends.

关键词： Oxygen Redox reactions Oxides Inorganic carbon compounds Fuels

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Spray morphology transformation of propane, n-hexane and iso-octane under flash-boiling conditions

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FUEL 2019年 236卷 677-685页

作者： Li, Yanfei Guo, Hengjie Zhou, Zhifu Zhang, Zhou Ma, Xiao Chen, Longfei Tsinghua Univ State Key Lab Automot Safety & Energy Beijing 100084 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Beihang Univ Sch Energy & Power Engn Beijing 100191 Peoples R China

Spray collapse has been widely observed under both flash-boiling and non-flash-boiling conditions when multihole gasoline direct injection (GDI) injectors with compact nozzle configurations were used. The main objective of this study is to further understand the collapse mechanisms by using liquids with appreciably different properties (propane, n-hexane and iso-octane). The tests were carried out in a constant volume vessel with ambient pressures ranging from 0.6 bar to 11.0 bar and fuel temperatures from 30 degrees C to 110 degrees C. Flashing propane sprays presented a non-collapse feature under elevated-ambient-pressures but flash-boiling conditions. By close-up examination of flashing propane sprays over a wide range of liquid temperatures and ambient pressures, it was found that there should be an ambient pressure threshold between 1.0 and 3.0 bar between the collapsed and the non-collapse sprays for propane. The spray collapse occurred as the ambient pressure is below the threshold. The non-collapse feature for flashing propane sprays under the ambient pressures beyond the threshold was attributed to the prohibition of nucleation and bubble growth under elevated ambient pressures.

关键词： Spray Flash boiling Gasoline direct injection Collapse Nucleation

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Global burden of asthma associated with high body mass index from 1990 to 2019

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ANNALS OF ALLERGY ASTHMA & IMMUNOLOGY 2022年第6期129卷 720-+页

作者： Liu, Jin Yuan, Maobo Chen, Yuqian Wang, Yan Wang, Qingting Zhang, Qianqian Chai, Limin Li, Danyang Qiu, Yuanjie Chen, Huan Wang, Jian Xie, Xinming Li, Manxiang Xi An Jiao Tong Univ Affiliated Hosp 1 Dept Resp & Crit Care Med Xian Peoples R China Xi An Jiao Tong Univ Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian Peoples R China Xi An Jiao Tong Univ Affiliated Hosp 1 Dept Resp & Crit Care Med 277 West Yanta Rd Xian 710061 Shaanxi Peoples R China

Background: High body mass index (BMI) plays a key role in the progression of asthma and asthma related to high BMI resulted in a high burden of disease ***: To explore the geographic and temporal trends in the global burden of asthma associated with high BMI from 1990 to ***: This is a retrospective analysis with data based on the Global Burden of Disease Study 2019 database. Deaths, disability-adjusted life-years (DALYs), age-standardized mortality rate (ASMR), and age-standardized DALY rate (ASDR) were estimated according to sex, age, and sociodemographic index levels. The estimated annual percentage change was used to evaluate the variation trends of ASMR and ASDR from 1990 to ***: In 2019, the number of global asthma deaths and DALYs related to high BMI increased by 69.69% and 63.91%, respectively, compared with 1990, among which more deaths and DALYs occurred in women. The corre-sponding ASMR and ASDR exhibited a slightly decreasing tendency globally. South Asia accounted for the highest number of deaths and DALYs, with India ranking first worldwide in 2019. The number of deaths and DALYs were mainly seen in individuals 60 to 79 years old and 55 to 69 years old, respectively, from 1990 to 2019. The heavi-est burden existed in the low-middle sociodemographic index ***: The global asthma burden associated with obesity increased in absolute value but the standardized burden decreased slightly. Large variations existed in the high BMI-related asthma burdens among sexes, ages, and regions.(c) 2022 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

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Velocimetry and thermometry in intermediate temperature flow using planar laser-induced fluorescence of OH from photo-dissociation of H2O

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EXPERIMENTS IN FLUIDS 2020年第8期61卷 183-183页

作者： Li, Guohua Ye, Jingfeng Zhang, Zhenrong Fang, Bolang Wang, Sheng Shao, Jun Hu, Zhiyun Wang, Jinhua Huang, Zuohua Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian Peoples R China Northwest Inst Nucl Technol State Key Lab Laser Interact Matter Xian Peoples R China

A technique for simultaneous velocimetry and thermometry in intermediate temperature flow is developed by combining hydroxyl-tagging velocimetry (HTV) and two-line OH planar laser-induced fluorescence (OH-PLIF). The OH tagging particles generated in HTV from the dissociation of water vapor are then used in two-line PLIF for thermometry. Using fragmentary OH expands PLIF to thermometry in regions that lack original OH, such as low temperature or unreactive ones. Meanwhile, using the PLIF system for both velocimetry and thermometry makes for a more efficient experimental system. As a proof of concept, the temperature and velocity are measured of a heated gas mixture comprising helium and water vapor. The temperature results agree well with the thermocouple results. [Graphical abstract]

关键词： Velocity measurement

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Fabrication of heterostructured UIO-66-NH2/CNTs with enhanced activity and selectivity over photocatalytic CO2 reduction

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2020年第55期45卷 30634-30646页

作者： Wang, Xiaojun Yang, Guorui Chai, Guodong Nasir, Muhammad Salman Wang, Silan Zheng, Xing Wang, Caiyun Yan, Wei Xi An Jiao Tong Univ Dept Environm Sci & Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Xi An Jiao Tong Univ Sch Sci Dept Appl ChemState Key Lab Elect Insulat & Powe MOE Key Lab Nonequilibrium Synth & Modulat Conden Xian 710049 Peoples R China Xi An Jiao Tong Univ Suzhou Inst Suzhou 215123 Peoples R China Xian Univ Technol State Key Lab Ecohydraul Northwest Arid Reg Xian 710048 Peoples R China Univ Wollongong ARC Ctr Excellence Electromat Sci Intelligent Polymer Res Inst Wollongong NSW 2522 Australia

Developing photocatalysts with superior efficiency and selectivity is an important issue for photocatalytic converting CO2. Hierarchically heterostructured one-dimensional nanomaterials represent a kind of promising catalysts for photocatalytic CO2 reduction on account of the high surface area and synthetic effect between different components. Herein, we synthesized UIO-66-NH2/carbon nanotubes (CNTs) heterostructures via a hydrothermal method, and investigated their photocatalytic performance. The element mapping, X-ray diffraction, and X-ray photoelectron spectroscopy collectively confirmed that the UIO-66-NH2 was successfully loaded on the surface of the CNTs. The specific surface area of the UI0-66-NH2/CNTs is 1.5 times higher than that of UIO-66-NH2. The photocurrent and electrochemical impedance spectroscopy measurements showed that the CNTs could enhance the electron mobility and reduce the recombination of photogenerated electronhole pairs, which was also confirmed by the Photoluminescence spectroscopy (PL). The CNTs can improve the conductivity of composites and the dispersion of UIO-66-NH2, exposing more active sites, therefore the UIO-66-NH2 can increase the absorption of carbon dioxide and thus enhance the selectivity. The composites remarkably promoted the separation and transition of electrons and thus improved the photocatalytic efficiency of CO2 reduction. More importantly, it was found that the as-prepared composites suppress the hydrogen generation reaction during the CO2 reduction process. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Carbon nanotubes Photocatalytic activity Selectivity UIO-66-NH2 CO2 reduction HCOOH

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