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Interfacial stress characterization of GaN epitaxial layer with sapphire substrate by confocal Raman spectroscopy

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Nanotechnology and Precision Engineering 2021年第2期4卷 9-19页

作者： Zengqi Zhang Zongwei Xu Ying Song Tao liu Bing Dong jiayu liu Hong Wang State Key Laboratory of Precision Measuring Technology and Instruments Centre of MicroNano Manufacturing TechnologyTianjin UniversityTianjin 300072China State Key Laboratory of Separation Membranes and Membrane Processes School of Materials Science and EngineeringTianjin Polytechnic UniversityTianjin 300387China

As an important wide-bandgap semiconductor,gallium nitride(GaN)has attracted considerable *** paper describes the use of confocal Raman spectroscopy to characterize undoped GaN,n-type GaN,and p-type GaN through depth profiling using 405-,532-,and 638-nm wavelength *** Raman signal intensity of the sapphire substrate at different focal depths is studied to analyze the depth *** on the shift of the E2 H mode of the GaN epitaxial layer,the interfacial stress for different types of GaN is characterized and *** results show that the maximum interfacial stress appears approximately at the junction of the GaN and the sapphire *** interfacial stress analysis between the GaN epitaxial layer and the substrate will be very helpful in furthering the applications of GaN devices.

关键词： Confocal Raman spectroscopy Gallium nitride Heteroepitaxial growth Interfacial stress

Low temperature one-pot synthesis of 1,1-diethoxyethane from ethanol on Bi/BiCeO_(x)with strong metal-support interactions

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Nano Research 2023年第3期16卷 3709-3718页

作者： Zhe An jiayu liu Meng Cao Jian Zhang Yanru Zhu Hongyan Song Xu Xiang Jing He State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing 100029China

The direct conversion of ethanol to 1,1-diethoxyethane(DEE)through one-pot dehydrogenation-acetalization has attracted broad interest from both academia and *** on thermodynamics,the oxidative dehydrogenation of alcohol to acetaldehyde requires high temperature to activate oxygen to realize the C-H cleavage,while the acetalization of acetaldehyde with ethanol is exothermic reversible reaction favorable at low *** mismatching of the reaction condition for the two consecutive steps makes it a great challenge to achieve both high ethanol conversion and high DEE *** work reports a highly efficient bi-functional catalysis by Bi/BiCeO_(x)for one-pot oxidative dehydrogenation-acetalization route from ethanol to DEE under 150℃and ambient pressure,affording a selectivity of 98.5%±0.5%to DEE at an ethanol conversion of 87.0%±1.0%.An efficient tandem catalysis has been achieved on the interfacial Bi^(δ)+-Ov-Ce^(III)sites in Bi/BiCeO_(x)established by strong metal-support interaction,in which Biδ+-Ov-sites contribute to the oxidative dehydrogenation of ethanol at mild temperature,and-Ov-CeIII sites to the subsequent acetalization between the generated acetaldehyde and ethanol.

关键词： ethanol conversion 1 1-diethoxyethane strong metal-support interaction Biδ+-Ov-CeIII sites

An infrared photothermoelectric detector enabled by MXene and PEDOT:PSS composite for noncontact fingertip tracking

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Microsystems & Nanoengineering 2023年第1期9卷 229-239页

作者： Jiaqi Wang Zhemiao Xie Guanxuan Lu jiayu Alexander liu John T.W.Yeow Advanced Micro-/Nano-Devices Lab Department of Systems Design EngineeringUniversity of Waterloo200 University Ave WestWaterlooONN2L 3G1Canada

Photothermoelectric(PTE)detectors functioning on the infrared spectrum show much potential for use in many fields,such as energy harvesting,nondestructive monitoring,and imaging *** advances in low-dimensional and semiconductor materials research have facilitated new opportunities for PTE detectors to be applied in material and structural ***,these materials applied in PTE detectors face some challenges,such as unstable properties,high infrared reflection,and miniaturization ***,we report our fabrication of scalable bias-free PTE detectors based on Ti3C2 and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate(PEDOT:PSS)composites and characterization of their composite morphology and broadband *** also discuss various PTE engineering strategies,including substrate choices,electrode types,deposition methods,and vacuum ***,we simulate metamaterials using different materials and hole sizes and fabricated a gold metamaterial with a bottom-up configuration by simultaneously combining MXene and polymer,which achieved an infrared photoresponse ***,we demonstrate a fingertip gesture response using the metamaterial-integrated PTE *** research proposes numerous implications of MXene and its related composites for wearable devices and Internet of Things(IoT)applications,such as the continuous biomedical tracking of human health conditions.

关键词： unstable composite sizes

Dysregulation of circular RNAs in inflammation and cancers

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Fundamental Research 2023年第5期3卷 683-691页

作者： jiayu liu Fangqing Zhao Ling-Ling Chen Shicheng Su Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation Medical Research CenterSun Yat-Sen Memorial HospitalSun Yat-Sen UniversityGuangzhou 510120China Breast Tumor Center Sun Yat-Sen Memorial HospitalSun Yat-Sen UniversityGuangzhou 510120China Beijing Institutes of Life Science Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Center for Excellence in Animal Evolution and Genetics Chinese Academy of SciencesKunming 650223China State Key Laboratory of Molecular Biology Shanghai Key Laboratory of Molecular AndrologyCAS Center for Excellence in Molecular Cell ScienceShanghai Institute of Biochemistry and Cell BiologyChinese Academy of SciencesShanghai 200031China School of Life Science and Technology ShanghaiTech UniversityShanghai 200092China School of Life Science Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesChinese Academy of SciencesHangzhou 310003China Department of Immunology Zhongshan School of MedicineSun Yat-Sen UniversityGuangzhou 510080China

Emerging lines of evidence have shown that the production of the covalently closed single-stranded circular RNAs is not splicing errors,but rather a regulated process with distinct biogenesis and *** RNAs are expressed in a cell type-and tissue-specific manner and often localize to specific subcellular regions or organelles for *** dysregulation of circular RNAs from birth to death is linked to the pathogenesis and progression of diverse *** review outlines how aberrant circular RNA biogenesis,subcellular location,and degradation are linked to disease progression,focusing on metaflammation and *** also discuss potential therapeutic strategies and obstacles in targeting such disease-related circular RNAs.

关键词： Circular RNA Metaflammation Biogenesis Degradation Subcellular localization

Regulation of the urea cycle by CPS1 O-GlcNAcylation in response to dietary restriction and aging

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Journal of Molecular Cell Biology 2022年第3期14卷 36-47页

作者： Jing Wu jiayu liu Kalina Lapenta Reina Desrouleaux Min-Dian Li Xiaoyong Yang Department of Comparative Medicine Department of Cellular and Molecular Physiologyand Yale Center for Molecular and Systems MetabolismYale University School of MedicineNew HavenCT 06520USA School of Life Science and Technology Xi’an Jiaotong UniversityXi’an 710049China

O-linked N-acetyl-glucosamine glycosylation(O-GlcNAcylation)of intracellular proteins is a dynamic process broadly implicated in age-related disease,yet it remains uncharacterized whether and how O-GlcNAcylation contributes to the natural aging process.O-GlcNAc transferase(OGT)and the opposing enzyme O-GlcNAcase(OGA)control this nutrient-sensing protein modification in ***,we show that global O-GlcNAc levels are increased in multiple tissues of aged *** aged liver,carbamoyl phosphate synthetase 1(CPS1)is among the most heavilyO-GlcNAcylated ***1O-GlcNAcylation is reversed by calorie restriction and is sensitive to genetic and pharmacological manipulations of theO-GlcNAc *** glucose stimulates CPS1O-GlcNAcylation and inhibits CPS1 ***-specific deletion of OGT potentiates CPS1 activity and renders CPS1 irresponsive to further stimulation by a prolonged *** results identify CPS1 O-GlcNAcylation as a key nutrient-sensing regulatory step in the urea cycle during aging and dietary restriction,implying a role for mitochondrial O-GlcNAcylation in nutritional regulation of longevity.

关键词： ageing O-GlcNAcylation urea cycle carbamoyl phosphate synthetase 1 calorie restriction posttranslational modification dietary restriction

PERFORMANCE IMPROVEMENT OF CENTRIFUGAL FAN BY MEANS OF NUMERICAL SIMULATION

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Chinese Journal of Mechanical Engineering 2006年第1期19卷 55-58页

作者： ZHANG Bo HUANG Shujuan SUN Zhongwei HUI Shien liu jiayu QI Chunsong Institute of Energy and Power Engineering Xi＇ an Jiaotong University Xi＇ an 710049 China Thermal Power Research Institute State Power Corporation of China Xi＇ an 710032 China

Numerical simulation is used to investigate the flow field in a model centrifugal fan for steam power stations in order to improve the performance. During testing the model fan, it is found that the efficiency is only 62.5% with inlet box, without it the efficiency is 83%. In addition, the strong vibration of test rig is observed with inlet box. It would be highly desirable if the aerodynamics of the fan could be studied. Therefore, numerical simulation is carried out to investigate the internal flow characteristics of a model fan with inlet box. The results from CFD analysis show that the whole region of the inlet box is occupied by a spiral vortex rotating inversely as the rotor＇s direction, which significantly affect the most flow＇region inside the fan. For this reason, a dummy plate is arranged in the inlet box to impede the generation of the spiral vortex, the results from CFD after the reform demonstrate that the modification is quiet effective, the former large spiral vertex has been destroyed effectively, the large one is superseded in favor of two small vortexes. However, two small vortexes have little effect on the inner flow of the rotor and the following parts. Finally, the efficiency of the model fan is improved by the test and the strong vibration of the test rig disappears. This type of modification has been used in steam power stations, the fan efficiency raises to 84% successfully.

关键词： Numerical simulation Centrifugal fan Vortex Performance improvement

Dynamic Load Restoration Considering the Interdependencies Between Power Distribution Systems and Urban Transportation Systems

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CSEE Journal of Power and Energy Systems 2020年第4期6卷 772-781页

作者： Ying Wang Yin Xu Jiaxu Li Chen Li Jinghan He jiayu liu Qiqi Zhang School of Electrical Engineering Beijing Jiaotong University(BJTU)Beijing 100044China State Grid Shanghai Electrical Power Company Research Institute Shanghai 200437China

After a major outage,mobile emergency resources(MERs)can be dispatched via the transportation system(TS)for service restoration to critical loads in the power distribution system(PDS).In this case study,the efficiency of service restoration in the PDS is associated with the traffic efficiency of the TS,and vice versa,because the PDS and TS are mutually coupled through traffic lights and *** paper proposes a service restoration method considering interdependency between the PDS and TS,which is formulated as a mixed-integer linear program(MILP).The objective includes maximizing the efficiency of both PDS restoration and *** solving the MILP,the dynamic load restoration and MER dispatch strategies can be *** the PDS,the availability of MERs,including mobile sources and repair crews,relates to their dispatch in the TS,and their relationship is formulated as mathematical *** the TS,the dynamic traffic flow is modeled using the cell transmission model and the effect of traffic lights is *** studies validate the effectiveness of the proposed method.

关键词： Mobile emergency resources power distribution systems resilience service restoration urban transportation systems

Earthworm biomass and population structure are negatively associated with changes in organic residue nitrogen concentration during vermicomposting

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Pedosphere 2021年第3期31卷 433-439页

作者： Bo ZHOU Yiyong CHEN Chi ZHANG Jianlong LI Hao TANG jiayu liu Jun DAI Jinchi TANG Tea Research Institute Guangdong Academy of Agricultural Sciences/Guangdong Provincial Key Laboratory of Tea Plant Resources Innovation and UtilizationGuangzhou 510640China College of Natural Resources and Environment South China Agricultural University/Key Laboratory of the Ministry of Agriculture for South China Farmland ConservationGuangzhou 510642China

Vermicomposting is an efficient and environmentally friendly technology to dispose of agricultural organic *** efficiency of organic residue decomposition during vermicomposting is directly affected by the biomass and population structure of *** this study,we investigated how the earthworm biomass and population structure responded to changes in the physicochemical properties of six types of organic residue(cattle dung,herbal waste,rice straw,soybean straw,garden waste,and tea residues)during *** type of organic residues was placed in a pot with earthworms Eisenia fetida,and the physicochemical properties of the organic residues and earthworm growth dynamics were recorded at 0,30,60,and 90 d of *** biomass and population structure of earthworms were stable or increased in rice straw,garden waste,and cattle dung within 60 d of vermicomposting,whereas in tea residues and herb waste,very little earthworm activity(3 adults and 2 cocoons)was recorded on day *** the physicochemical parameters,the substrate C/N ratio was negatively correlated with earthworm growth *** organic residues showed higher NH_(4)^(+)-N and NH_(3)^(-)-N concentrations but a lower total organic carbon content,which negatively affected earthworm growth and *** recommend that chemical properties of vermicomposting systems should be monitored *** the threshold levels of decomposing organic residue NH_(4)^(+)-N and NH_(3)^(-)-N concentrations,earthworms should be removed and the vermicompost can be ***-and large-scale farmers thus need to monitor the physicochemical properties of vermicompost to sustain active earthworm populations.

关键词： ammonium nitrogen decomposing earthworm biological traits Eisenia fetida nitrate nitrogen organic residue dispose physicochemical property

Understanding and improving fairness in cognitive diagnosis

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Science China(Information Sciences) 2024年第5期67卷 99-114页

作者： Zheng ZHANG Le WU Qi liu jiayu liu Zhenya HUANG Yu YIN Yan ZHUANG Weibo GAO Enhong CHEN Anhui Province Key Laboratory of Big Data Analysis and Application School of Computer Science and Technology& School of Data Science University of Science and Technology of China State Key Laboratory of Cognitive Intelligence School of Computer Science and Information Engineering Hefei University of Technology

Intelligent education is a significant application of artificial intelligence. One of the key research topics in intelligence education is cognitive diagnosis, which aims to gauge the level of proficiency among students on specific knowledge concepts(e.g., Geometry). To the best of our knowledge, most of the existing cognitive models primarily focus on improving diagnostic accuracy while rarely considering fairness issues; for instance, the diagnosis of students may be affected by various sensitive attributes(e.g., region). In this paper,we aim to explore fairness in cognitive diagnosis and answer two questions:(1) Are the results of existing cognitive diagnosis models affected by sensitive attributes?(2) If yes, how can we mitigate the impact of sensitive attributes to ensure fair diagnosis results? To this end, we first empirically reveal that several wellknown cognitive diagnosis methods usually lead to unfair performances, and the trend of unfairness varies among different cognitive diagnosis models. Then, we make a theoretical analysis to explain the reasons behind this phenomenon. To resolve the unfairness problem in existing cognitive diagnosis models, we propose a general fairness-aware cognitive diagnosis framework, FairCD. Our fundamental principle involves eliminating the effect of sensitive attributes on student proficiency. To achieve this, we divide student proficiency in existing cognitive diagnosis models into two components: bias proficiency and fair *** design two orthogonal tasks for each of them to ensure that fairness in proficiency remains independent of sensitive attributes and take it as the final diagnosed result. Extensive experiments on the Program for International Student Assessment(PISA) dataset clearly show the effectiveness of our framework.

关键词： fairness intelligent education cognitive diagnosis psychometrics adversarial learning