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Micro-arc oxidization fabrication and ethanol sensing performance of Fe-doped TiO_2 thin films

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International Journal of Minerals,Metallurgy and Materials 2012年第5期19卷 461-466页

作者： Fu-jian Ren Xiao-bai Yu yun-han ling Jia-you Feng Laboratory of Advanced Materials Department of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

In-situ pure TiO2 and Fe-doped TiO2 thin films were synthesized on Ti plates via the micro-arc oxidation （MAO） technique. The as-fabricated anatase TiO2 thin film-based conductometric sensors were employed to measure the gas sensitivity to ethanol. The results showed that Fe ions could be easily introduced into the MAO-TiO2 thin films by adding precursor K4（FeCN）6＇3H20 into the NaaPO4 electrolyte. The amount of doped Fe ions increased almost linearly with the concentration of Kg（FeCN）63H20 increasing, eventually affecting the ethanol sensing performances of TiO2 thin films. It was found that the enhanced sensor signals obtained had an optimal concentration of Fe dopant （1.28at%）, by which the maximal gas sensor signal to 1000 ppm ethanol was estimated to be 7.91 at 275℃. The response time was generally reduced by doped Fe ions, which could be ascribed to the increase of oxygen vacancies caused by Fe3＋ substituting for Ti4＋.

关键词： thin films titanium dioxide doping iron micro-arc oxidation ethanol sensors

Construction of flower-like MoS_(2)decorated on Cu doped CoZn-ZIF derived N-doped carbon as superior microwave absorber

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Nano Research 2024年第9期17卷 8250-8260页

作者： yun han Di Lan Mengjun han Zihao Xia Jiaxiao Zou Zirui Jia College of Chemistry and Chemical Engineering Qingdao UniversityQingdao 266071China School of Materials Science and Engineering Hubei University of Automotive TechnologyShiyan 442002China

The rational design of composition nanostructures and morphologies of the carbon-based composites materials has a significant potential for tuning electromagnetic parameters and thereby improving their performance as electromagnetic wave(EMW)*** this work,the flower-like Cu/Co-NC/MoS_(2)(NC=N-doped carbon skeleton)composites were successfully prepared by employing CuCoZn-ZIF(ZIF=zeolitic imidazolate framework)as precursor with subsequent annealing and hydrothermal *** unique flower-like morphology and electromagnetic synergy strategy between components enable the as-obtained Cu/Co-NC/MoS_(2)composites to exhibit outstanding microwave absorption ***,the minimum reflection loss of Cu/Co-NC/MoS_(2)reaches-54.36 dB at 2.7 *** the thickness reduces to 2.2 mm,the maximum effective absorption bandwidth can be achieved as large as 6.72 *** research develops useful ideas for optimizing multicomponent microwave absorbing materials.

关键词： ternary metal-organic frameworks(MOFs) MoS_(2) flower-like morphology microwave absorption

Microstructure and properties of hydrophobic films derived from Fe-W amorphous alloy

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International Journal of Minerals,Metallurgy and Materials 2014年第4期21卷 395-400页

作者： Song Wang yun-han ling Jun Zhang Jian-jun Wang Gui-ying Xu School of Materials Science and Engineering University of Science and Technology Beijing School of Materials Science and Engineering Tsinghua University

Amorphous metals are totally different from crystalline metals in regard to atom arrangement. Amorphous metals do not have grain boundaries and weak spots that crystalline materials contain, making them more resistant to wear and corrosion. In this study, amorphous Fe-W alloy films were first prepared by an electroplating method and were then made hydrophobic by modification with a water repellent （heptadecafluoro-1,1,2,2-tetradecyl） trimethoxysilane. Hierarchical micro-nano structures can be obtained by slightly oxidizing the as-deposited alloy, accompanied by phase transformation from amorphous to crystalline during heat treatment. The mi-cro-nano structures can trap air to form an extremely thin cushion of air between the water and the film, which is critical to producing hydrophobicity in the film. Results show that the average values of capacitance, roughness factor, and impedance for specific surface areas of a 600°C heat-treated sample are greater than those of a sample treated at 500°C. Importantly, the coating can be fabricated on various metal substrates to act as a corrosion retardant.

关键词： iron tungsten alloys amorphous films hydrophobicity microstructure contact angle capacitance

Unveiling the role of hypoxia-inducible factor 2alpha in osteoporosis:Implications for bone health

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World Journal of Stem Cells 2024年第4期16卷 389-409页

作者： ling-ling Wang Zhan-Jin Lu Shun-Kui Luo yun Li Zhe Yang Hong-yun Lu Department of Gerontology The Fifth Affiliated Hospital of Sun Yat-sen UniversityZhuhai 519000Guangdong ProvinceChina Department of Endocrinology and Metabolism The Fifth Affiliated Hospital of Sun Yat-sen UniversityZhuhai 519000Guangdong ProvinceChina Guangdong Provincial Key Laboratory of Biomedical Imaging The Fifth Affiliated Hospital of Sun Yat-sen UniversityZhuhai 519000Guangdong ProvinceChina Department of Endocrinology and Metabolism Zhuhai People’s Hospital(Zhuhai Clinical Medical College of Jinan Universitythe First Hospital Affiliated with Medical College of Macao University of Science and Technology)Zhuhai 519000Guangdong ProvinceChina

BACKGROUND Osteoporosis(OP)has become a major public health problem *** OP treatments are based on the inhibition of bone resorption,and it is necessary to identify additional treatments aimed at enhancing *** the bone marrow(BM)niche,bone mesenchymal stem cells(BMSCs)are exposed to a hypoxic ***,a few studies have demonstrated that hypoxiainducible factor 2alpha(HIF-2α)is involved in BMSC osteogenic differentiation,but the molecular mechanism involved has not been *** To investigate the effect of HIF-2αon the osteogenic and adipogenic differentiation of BMSCs and the hematopoietic function of hematopoietic stem cells(HSCs)in the BM niche on the progression of *** Mice with BMSC-specific HIF-2αknockout(Prx1-Cre;Hif-2αfl/fl mice)were used for in vivo *** quantification was performed on mice of two genotypes with three interventions:Bilateral ovariectomy,semilethal irradiation,and dexamethasone ***,the hematopoietic function of HSCs in the BM niche was compared between the two mouse *** vitro,the HIF-2αagonist roxadustat and the HIF-2αinhibitor PT2399 were used to investigate the function of HIF-2αin BMSC osteogenic and adipogenic ***,we investigated the effect of HIF-2αon BMSCs via treatment with the mechanistic target of rapamycin(mTOR)agonist MHY1485 and the mTOR inhibitor *** The quantitative index determined by microcomputed tomography indicated that the femoral bone density of Prx1-Cre;Hif-2αfl/fl mice was lower than that of Hif-2αfl/fl mice under the three intervention *** vitro,Hif-2αfl/fl mouse BMSCs were cultured and treated with the HIF-2αagonist roxadustat,and after 7 d of BMSC adipogenic differentiation,the oil red O staining intensity and mRNA expression levels of adipogenesis-related genes in BMSCs treated with roxadustat were decreased;in addition,after 14 d of osteogenic differentiation,BMSCs treated with roxadusta

关键词： Hypoxia-inducible factor-2α Bone marrow niche Bone mesenchymal stem cells Osteoporosis Osteogenic/adipogenic differentiation Mechanistic target of rapamycin signaling pathway

Clustering for Bivariate Functional Data

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Acta Mathematicae Applicatae Sinica 2024年第3期40卷 613-629页

作者： Shi-yun CAO Yan-qiu ZHOU Yan-ling WAN Tao ZhanG School of Science Guangxi University of Science and TechnologyLiuzhou 545006China School of Marxism Guangxi University of Science and TechnologyLiuzhou 545006China Key Laboratory of Intelligent Information Processing and Graph Processing Guangxi University of Science and TechnologyLiuzhou 545006China

In this paper,we consider the clustering of bivariate functional data where each random surface consists of a set of curves recorded repeatedly for each *** k-centres surface clustering method based on marginal functional principal component analysis is proposed for the bivariate functional data,and a novel clustering criterion is presented where both the random surface and its partial derivative function in two directions are *** addition,we also consider two other clustering methods,k-centres surface clustering methods based on product functional principal component analysis or double functional principal component *** results indicate that the proposed methods have a nice performance in terms of both the correct classification rate and the adjusted rand *** approaches are further illustrated through empirical analysis of human mortality data.

关键词： bivariate functional data -centres surface clustering functional principal component analysis partial derivative function

Simple point contact WO_3 sensor for NO_2 sensing and relevant impedance analysis

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International Journal of Minerals,Metallurgy and Materials 2012年第12期19卷 1142-1148页

作者： Wu-bin Gao yun-han ling Xu Liu Jia-lin Sun School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

A simple and new point contact tungsten trioxide （WO3） sensor, which can be prepared by the oxidation of tungsten filaments via in-situ induction heating, likely detects low concentration （ppm level） environmental pollutants such as NO2. X-ray diffraction （XRD） and field emission scanning electron microscopy （FE-SEM） were applied to characterize the phase and the microstructure of the samples, respec-tively. It was found that the synthesized WO3 films exhibited a monoclinic phase and were composed of hierarchical microcrystals and nanocrystals. The point contact WO3 sensor （W-WO3-W） showed rectifying characteristics and an ideal sensing performance of about 110 C. A single semicircle in Nyquist plots was recorded by electrochemical impedance spectroscopy （EIS） at a relatively low temperature of 150 C but faded away above 200 C, which revealed that the sensing process was governed by a determining factor, i.e., grain boundaries at the contact site.

关键词： gas sensors tungsten trioxide metal oxide semiconductors thin fills microcrystals nanocrystals electrochemical impedancespectroscopy (EIS)

Flow Boiling Heat Transfer Characteristics and Delayed Dry-Out Ability of Non-Azeotropic Mixtures R245fa/R134a in Microchannels

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Journal of Thermal Science 2024年第3期33卷 1174-1188页

作者： LU Yongjie ling Yongjun ZHUANG Yuan LI Chenyang OUYANG Hongsheng han Xiaohong Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province Institute of Refrigeration and CryogenicsZhejiang UniversityHangzhou310007China Zhejiang Zhongguang Electrical Co. Ltd.Lishui323000China State Key Lab for Fluorine Greenhouse Gases Replacement and Control Treatment Zhejiang Research Institute of Chemical IndustryHangzhou310014China

Microchannel flow boiling heat transfer has the advantages of strong heat dissipation capacity,good temperature uniformity,and compact *** is an excellent way to thermally manage electronic devices,but when the heat flux exceeds CHF(Critical Heat Flux),the heat transfer performance deteriorates as the working fluid dries ***-azeotropic mixtures have the potential to effectively delay or avoid dry-out during the boiling process due to their temperature slide characteristics which causes the mass transfer *** understand the influence of non-azeotropic mixtures on microchannel flow boiling,using the phase-change microchannel heat sink as the research object,the experiments on the flow boiling heat transfer performance of R245fa/R134a mixtures under different working conditions were carried out,and the characteristics of flow boiling heat transfer were obtained under the different working conditions,and comparison was developed with those of pure substance *** results demonstrated that a small amount of low-boiling-point components in the high-boiling-point working fluid inhibited boiling heat transfer to some extent,and lowered the average heat transfer coefficient under the non-dryout condition slightly lower than that of the pure substance;however,it also effectively delayed the onset of local dry-out and prevented significant deterioration in thermal transfer performance under the lower mass flow rate and higher heat flux,which could enhance the heat sink's stability.

关键词： microchannel flow boiling non-azeotropic mixture heat transfer characteristics dry-out

Effect of initial ammonium concentration on a one-stage partial nitrification/anammox biofilm system:Nitrogen removal performance and the microbial community

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Journal of Environmental Sciences 2024年第9期143卷 176-188页

作者： Mengyu Zhou yun han Yang Zhuo Fen Yu Gaoyuan Hu Dangcong Peng School of Municipal and Environmental Engineering Xi’an University of Architecture and TechnologyXi’an 710055China Shaanxi Key Laboratory of Environmental Engineering Xi’an University of Architecture and TechnologyXi’an 710055China Key Laboratory of Northwest Water Resource Environment and EcologyMOEXi’an University of Architecture and TechnologyXi’an 710055China

One-stage partial nitrification coupled with anammox(PN/A)technology effectively reduces the energy consumption of a biological nitrogen removal *** nitrite-oxidizing bacteria(NOB)is essential for this technology to maintain efficient nitrogen removal *** ammonium concentration(IAC)affects the degree of inhibited *** this study,the effect of the IAC on a PN/A biofilm was investigated in a moving bed biofilm *** results showed that nitrogen removal efficiency decreased from 82.49%±1.90%to 64.57%±3.96%after the IAC was reduced from 60 to 20 mg N/L,while the nitrate production ratio increased from 13.87%±0.90%to 26.50%±3.76%.NOB activity increased to1,133.86 mg N/m^(2)/day after the IAC decreased,approximately 4-fold,indicating that the IAC plays an important inhibitory role in *** rate-limiting step in the mature biofilm of the PN/A system is the nitritation process and is not shifted by the *** analysis of the microbial community structure in the biofilm indicates that the IAC was the dominant factor in changes in community *** and *** were the main anammox bacteria,and Nitrosomonas and Nitrospira were the main AOB and NOB,*** did not affect the difference in growth between *** and ***,modulating the IAC promoted the PN/A process with efficient nitrogen removal performance at medium to low ammonium concentrations.

关键词： Biological nitrogen removal Partial nitrification Anammox Ammonium concentration Biofilm

A Possible X-ray Quasi-periodic Oscillation in the Narrow-line Seyfert 1 Galaxy Mrk 142

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Research in Astronomy and Astrophysics 2024年第6期24卷 191-200页

作者： Xiao-Gu Zhong Jian-Cheng Wang Yong-yun Chen Xiao-ling Yu College of Physics and Electronic Engineering Qujing Normal UniversityQujing 655011China yunnan Observatories Chinese Academy of SciencesKunming 650216China

A possible quasi-periodic oscillation(QPO) at frequency 7.045 × 10^(-5) Hz is found in the narrow-line Seyfert 1galaxy Mrk 142 in the data of XMM-Newton collected on 2020 April *** find that the QPO signal is statistically significantly larger than the 5σ level and highly coherent with quality factor Q > 5 at the 0.3–10 keV band by using the method of the Lomb–Scargle Periodogram,the Weighted Wavelet Z-transform and the *** analyze the data in 0.3–0.6 keV,0.6–1 keV,1–3 keV and 3–10 keV energy bands,and find obvious QPO signals at 0.3–0.6 keV and 1–3 keV *** then analyze the time-average spectra and time variability at the QPO frequency of 7.045 × 10^(-5) Hz,and use a model to fit *** find that the QPO signal mainly comes from the X-ray hot corona.

关键词： X-rays:galaxies galaxies:Seyfert accretion accretion disks radiation mechanisms:general