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Thermodynamic and kinetics of hydrogen photoproduction enhancement by concentrated sunlight with CO_(2) photoreduction by heterojunction photocatalysts

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能源与人工智能(英文) 2021年第4期6卷 14-20页

作者： Ziyu Liu Teng Yi Chenxu Huang kwang-leong choy Chaozong Liu School of Medical Science and Engineering Beihang UniversityChina Centre for Materials Research University College LondonUK National Institude of Defense Science and Technology China Northwest Institute of Mechanical&Electrical Engineering China

For achieving water splitting into hydrogen under sunlight for practical applications,the high efficiencies of the photoreduction of CO_(2) over TiO_(2)/Fe3O4 photocatalysts combined with hydrogenation of water splitting over Pt/TiO_(2) were investigated by practical concentrated solar energy compared with Hg lamp and Xe *** on AI analysis on the influence factors,the key parameters for TOC concentration were photocatalysts,Na2CO3 concentration and radiation intensity while the key parameters for hydrogen production were photocatalysts,radiation intensity,and TOC ***,the mechanism of concentrated sunlight effects has been discussed from the view of thermodynamics and *** concentrated sunlight provides a simultaneous supply of sufficient electron–hole pairs and thermal *** to hydrogen and CO_(2) reduction are both enhanced in concentrated sunlight due to endothermal *** changes the internal electric field of p-n junction of in different possible ways,and thus composite photocatalysts with favorable formation of p-n junctions would enhance the charge separation by internal electric ***,photocatalysts are beneficial for providing more excited electrons at a time for achieving CO_(2) photoreduction at the surface region of the particles with higher density of radiation by concentrated solar ***,products from CO_(2) photoreduction,acting as sacrificial electron donors,improved hydrogen evolution in solar-mediated water splitting for prohibiting reverse reactions.

关键词： Concentrated sunlight Hydrogen evolution CO_(2)photoreduction p-n junction Thermodynamics and kinetics

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Negative permittivity derived from inductive characteristic in the percolating Cu/EP metacomposites

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Journal of Materials Science & Technology 2019年第11期35卷 2463-2469页

作者： Kai Sun Jiahao Xin Yaping Li Zhongyang Wang Qing Hou Xiaofeng Li Xinfeng Wu Runhua Fan kwang leong choy College of Ocean Science and Engineering Shanghai Maritime UniversityShanghai201306China Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong UniversityJinan250061China Department of Materials Science and Engineering National University of SingaporeSingapore119077Singapore Department of Chemistry University College LondonLondonWC1H 0AJUK UCL Institute for Materials Discovery University College LondonLondonWC1E 7JEUK

Recently,increasing attention has been concentrated on negative permittivity with the development of the emerging metamaterials composed of periodic array ***,taking facile preparation into consideration,it is important to achieve negative permittivity behavior based on materials'intrinsic properties rather than their artificially periodic *** this paper,we proposed to fabricate the percolating composites with copper dispersed in epoxy(EP)resin by a polymerization method to realize the negative permittivity *** Cu content in the composites reached to 80 wt%,the conductivity abruptly went up by three orders of magnitudes,suggesting a percolation *** the percolation threshold,the conductivity spectra conform to Jonscher's power law;when the Cu/EP composites reached to percolating state,the conductivity gradually reduced in high frequency region due to the skin *** is indicated that the conductive mechanism changed from hopping conduction to electron *** addition,the permittivity did not increase monotonously with the increase of Cu content in the vicinity of percolation threshold,due to the presence of leakage ***,the negative permittivity conforming to Drude model was observed above the percolation *** investigation revealed that there was a constitutive relationship between the permittivity and the *** conductive fillers are slightly above the percolation threshold,the inductive characteristic derived from conductive percolating network leads to the negative *** epsilon-negative materials can potentially be applied in novel electrical devices,such as high-power microwave filters,stacked capacitors,negative capacitance field effect transistors and coil-free *** addition,the design strategy based on percolating composites provides an approach to epsilon-negative materials.

关键词： Negative permittivity Epsilon-negative materials Percolating composites Metacomposites Metamaterials

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Innovation in Surface Coating Technology

Innovation in Surface Coating Technology

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第十届中国钢铁年会暨第六届宝钢学术年会

作者： kwang leong choy Institute for Materials Discovery University College of London

This contribution presents an overview of the use of chemical vapour deposition（CVD） and physical vapour deposition（PVD） for the manufacture of high quality structural and functional coatings onto steel. The scientific and technological significant of these methods will be discussed and reviewed. In addition, the emerging, innovative and cost-effective non vacuum aerosol assisted chemical vapour deposition（AACVD） will be highlighted. AACVD is a variant of the CVD process. It has the capability to deposit high purity nanostructured thin and thick films onto steel well controlled structure and composition at molecular scale level and at low processing temperatures. The fundamental aspects of AACVD including process principle, deposition mechanism, reaction chemistry, kinetics, and mass transport phenomena will be presented. The relationships of the process/structure/property of the coatings manufactured by the AACVD based methods will be described. The microstructure and properties of the nanostructured materials produced by AACVD method will be described and compared with conventional CVD and PVD coating techniques. The use of the promising non vacuum deposition AACVD based technology for the creation of potential high value added steel products will be presented. The technical viability and the potential of the AACVD process to be scaled up or large area and large scale production will be presented.

关键词： chemical vapour deposition(CVD) AACVD steel substrates coating

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Multifunctional two-dimensional glassy graphene devices for vis-NIR photodetection and volatile organic compound sensing

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Science China Materials 2021年第8期64卷 1964-1976页

作者： Xiao Li Xiao Dai Hao Xu Kai Shen Jian Guo Caihong Li Guifu Zou kwang-leong choy Ivan PParkin Zhengxiao Guo Huiyun Liu Jiang Wu Department of Electronic and Electrical Engineering University College LondonTorrington PlaceLondon WC1E 7JEUnited Kingdom Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of ChinaChengdu 610054China School of Energy Soochow Institute for Energy and Materials Innovationsand Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu ProvinceSoochow UniversitySuzhou 215006China Department of Chemistry University College London20 Gordon StreetLondon WC1H 0AJUnited Kingdom Institute for Materials Discovery University College LondonRoberts BuildingMalet PlaceLondon WC1E 7JEUnited Kingdom Departments of Chemistry and Mechanical Engineering The University of Hong KongHong Kong SARChina Zhejiang Institute of Research and Innovation The University of Hong KongQingshan Lake SciTech CityHangzhou 311305China

Multifunctional devices are of great interest for integration and miniaturization on the same platform, but simple addition of functionalities would lead to excessively large devices. Here, the photodetection and chemical sensing device is developed based on two-dimensional(2D) glassygraphene that meets similar property requirements for the two functionalities. An appropriate bandgap arising from the distorted lattice structure enables glassy graphene to exhibit comparable or even improved photodetection and chemical sensing capability, compared with pristine graphene. Due to strong interactions between glassy graphene and the ambient atmosphere, the devices are less sensitive to photoinduced desorption than the ones based on graphene. Consequently,the few-layer glassy graphene device delivers positive photoresponse, with a responsivity of 0.22 A W^(-1) and specific detectivity reaching ~10^(10) Jones under 405 nm ***, the intrinsic defects and strain in glassy graphene can enhance the adsorption of analytes, leading to high chemical sensing performance. Specifically, the extracted signalto-noise-ratio of the glassy graphene device for detecting acetone is 48, representing more than 50% improvement over the device based on graphene. Additionally, bias-voltage-and thickness-dependent volatile organic compound(VOC) sensing features are identified, indicating the few-layer glassy graphene is more sensitive. This study successfully demonstrates the potential of glassy graphene for integrated photodetection and chemical sensing, providing a promising solution for multifunctional applications further beyond.

关键词： glassy graphene multifunctional device photodetection volatile organic compounds liquid sensing

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Preparation of Sub-10nm Cored Ni@ZrO2 yolk-shell structured catalysts and its sintering-resistant property in steam reforming of methane

Preparation of Sub-10nm Cored Ni@ZrO2 yolk-shell structured ...

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第十四届全国青年催化学术会议

作者： Zi-Yian Lim Chunzheng Wu Chen Zhou Hongfeng Yin kwang-leong choy Wei Guo Wang Fuel Cells & Energy Technology Division Ningbo Institute of Material Technology and Engineering Ningbo Industrial Technology Research Institute CAS Division of Science and Engineering The University of Nottingham Ningbo China University Park

＜正＞Nickel-based catalysts have been developed as promising candidates for steam reforming of methane. However, their stability has been restricted due to agglomeration among active particles at high temperatures. In the present work, Ni/ZrO2 yolk shell nano-reactor framework has been proposed, where Ni cores are inside the hollow zirconia shells. The catalyst has been prepared

关键词： Yolk-Shell Steam reforming Methane Sintering-resistant

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Prediction of fracture initiation in cohesive soils based on data mining modelling and large-scale laboratory verification

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Underground Space 2024年第6期19卷 279-300页

作者： Weiping Luo Dajun Yuan Yannick choy Hing Ng Dalong Jin Ping Lu Teng Wang Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China Key Laboratory of the Ministry of Education for Urban Underground Engineering Beijing Jiaotong UniversityBeijing 100044China Department of Civil and Environmental Engineering National University of SingaporeSingapore 119077Singapore

Many empirical and analytical methods have been proposed to predict fracturing pressure in cohesive *** of them take into account three to four specific influencing factors and rely on the assumption of a failure *** this study,a novel data-mining approach based on the XGBoost algorithm is investigated for predicting fracture initiation in cohesive *** has the advantage of handling multiple influencing factors simultaneously,without pre-determining a failure mode.A dataset of 416 samples consisting of 14 distinct features was herein collected from past studies,and used for developing a regressor and a classifier model for fracturing pressure prediction and failure mode classification *** results show that the intrinsic characteristics of the soil govern the failure mode while the fracturing pressure is more sensitive to the stress *** XGBoost-based model was also tested against conventional approaches,as well as a similar machine learning algorithm namely random forest ***,several large-scale triaxial fracturing tests and an in-situ case study were carried out to further verify the generalization ability and applicability of the proposed data mining approach,and the results indicate a superior performance of the XGBoost model.

关键词： Fracturing pressure Failure mode Cohesive soil Data-mining Large-scale tests

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Assessing the Applicability of Multi-Source Precipitation Products over the Chinese Mainland and Its Seven Regions

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Journal of Tropical Meteorology 2024年第3期30卷 275-288页

作者： TIAN Wei WU Yun-long LIN Chen ZHANG Jing-guo LIM KAM SIAN Kenny Thiam choy School of Computer and Software Nanjing University of Information Science&TechnologyNanjing 210044 China School of Atmospheric Science and Remote Sensing Wuxi UniversityWuxiJiangsu 214105 China

Satellite-based and reanalysis precipitation products provide valuable information for various ***,their performance varies widely across regions due to different data sources and production *** paper evaluated the daily performance of four precipitation products(MSWEP,ERA5,PERSIANN,and TRMM)for seven regions of the Chinese mainland,using observations from 2462 ground stations across the country as a *** used four statistical and four classification indicators to describe their spatial and temporal accuracy,and capability to detect precipitation events while analyzing their *** results show that according to the precipitation char-acteristics and accuracy of different types of precipitation products over the Chinese mainland,MSWEP was the most suitable product over the Chinese mainland,having the lowest root mean square error and mean absolute error,along with the highest coefficient of *** was followed by TRMM and ERA5,whereas PERSIANN lagged behind in terms of *** terms of different regions,MSWEP still performed well,especially in North China and East *** accuracy of the four precipitation products was relatively low in the summer months,and they all overestimated in the northwest *** other months,MSWEP and TRMM were better than PERSIANN and *** four precipitation products had good detection performance over the Chinese mainland,with probability of detection above ***,with the increase of precipitation threshold,the detection capability of the four products decreased,and MSWEP and ERA5 had good detection capability for moderate ***’s detection capability for heavy rain and rainstorms was better than that of the other three products,and PERSIANN’s detection capability for moderate rain,heavy rain and rainstorms was relatively poor,with a large deviation.

关键词： precipitation product MSWEP TRMM ERA5 PERSIANN

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Deep learning-based modeling method for probabilistic LCF life prediction of turbine blisk

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Propulsion and Power Research 2024年第1期13卷 12-25页

作者： Cheng-Wei Fei Yao-Jia Han Jiong-Ran Wen Chen Li Lei Han Yat-Sze choy Department of Aeronautics and Astronautics Fudan UniversityShanghai 200433China Department of Mechanical Engineering Hong Kong Polytechnic UniversityHong Kong 999077China

Turbine blisk is one of the typical components of gas turbine *** fatigue life of turbine blisk directly affects the reliability and safety of both turbine blisk and aeroengine *** monitor the performance degradation of an aeroengine,an efﬁcient deep learning-based modeling method called convolutional-deep neural network(C-DNN)method is proposed by absorbing the advantages of both convolutional neural network(CNN)and deep neural network(DNN),to perform the probabilistic low cycle fatigue(LCF)life prediction of turbine blisk regarding uncertain influencing *** the C-DNN method,the CNN method is used to extract the useful features of LCF life data by adopting two convolutional layers,to ensure the precision of C-DNN *** two close-connected layers in DNN are employed for the regression modeling of aeroengine turbine blisk LCF life,to keep the ac-curacy of LCF life *** the probabilistic analysis of turbine blisk and the com-parison of methods(ANN,CNN,DNN and C-DNN),it is revealed that the proposed C-DNN method is an effective mean for turbine blisk LCF life prediction and major factors affecting the LCF life were gained,and the method holds high efﬁciency and accuracy in regression modeling and *** study provides a promising LCF life prediction method for complex structures,which contribute to monitor health status for aeroengines operation.

关键词： Convolutional-deep neural network Low cycle fatigue Life prediction Turbine blisk Probabilistic prediction

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Weight regain after intragastric balloon for pre-surgical weight loss

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World Journal of Gastrointestinal Surgery 2024年第7期16卷 2040-2046页

作者： Danielle Abbitt Kevin choy Alexandra Kovar Teresa S Jones Krzysztof J Wikiel Edward L Jones Department of Surgery University of ColoradoAuroraCO 80045United States Department of Surgery Rocky Mountain Regional Veteran Affairs Medical CenterAuroraCO 80045United States

BACKGROUND Over one-third of Americans carry the diagnosis of obesity,many also with obesity-related *** can place patients at increased risk of operative and postoperative *** intragastric balloon has been shown to aid in minor weight loss,however its weight recidivism in patients requiring short interval weight loss has not been well *** To evaluate weight loss,ability to undergo successful elective surgery after intragastric balloon placement,and weight management after balloon *** This study is a retrospective review of patients in a single academic institution undergoing intragastric balloon placement from 2019-2023 to aid in weight loss prior to undergoing elective *** outcomes including weight loss,duration of balloon placement,successful elective surgery,weight regain postballoon and post-procedure complications were *** criteria included those with balloon in place at time of *** Thirty-three patients completed intragastric balloon therapy from 2019-2023 as a bridge to elective *** patients were required to participate in a 12-month weight management program to be eligible for balloon *** surgeries included incisional hernia repair,umbilical hernia repair,inguinal hernia repair,and knee and hip *** average age at placement was 53 years±11 years,majority(91%)were *** average duration of intragastric balloon therapy was 186 days±41 *** average weight loss was 14.0 kg±7.4 kg and with an average percent excess body weight loss of 30.0%(7.9%-73.6%).Over half of the patients(52.0%)achieved the goal of 30-50 lbs(14-22 kg)weight ***-one patients(64%)underwent their intended elective surgery,2 patients(6%)deferred surgery due to symptom relief with weight loss ***-one of the patients(64%)have documented weights in 3 months after balloon removal,in these patients the majority(76%)gained weight after balloon *** pat

关键词： Intragastric balloon Weight loss Obesity Bariatric Body mass index

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Oxidative spirolactonisation for modular access of γ-spirolactones via a radical tandem annulation pathway

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Chinese Chemical Letters 2024年第10期35卷 249-252页

作者： Jindian Duan Xiaojuan Ding Pui Ying choy Binyan Xu Luchao Li Hong Qin Zheng Fang Fuk Yee Kwong Kai Guo College of Biotechnology and Pharmaceutical Engineering State Key Laboratory of Materials-Oriented Chemical EngineeringNanjing Tech UniversityNanjing 211816China Department of Chemistry and State Key Laboratory of Synthetic Chemistry The Chinese University of Hong KongHong KongChina

An oxidative annulation of 2-arylidene-1,3-indanediones with Meldrum's acid has been developed for the divergent syntheses of spirolactones with a spirocenter located at theγ-position with respect to the carbonyl *** heteroannulation protocol tolerates various functional groups and delivers moderate-to-good product ***,the reaction outcomes are exclusively controlled by the reaction oxidant/*** annulation strategy can also be executed in the flow system with decent product *** experiments revealed that the reaction proceeds via a radical tandem annulation pathway.

关键词： Spirolactonisation y-Spirolactones 2-Arylidene-1,3-indanediones Meldrum's acid Divergentsynthesis

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