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Facile preparation of Fe/N-based biomass porous carbon composite towards enhancing the thermal decomposition of DAP-4

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Defence Technology（防务技术） 2024年第1期31卷 288-294页

作者： Er-hai An Xiao-xia Li Cun-juan Yu Ying-xin Tan Zi-jun Fan Qing-xia Li peng Deng Xiong cao School of Environment and Safety Engineering North University of ChinaTaiyuan030051PR China College of Safety and Emergency Management Engineering Taiyuan University of Science and TechnologyTaiyuan030024PR China

Fe/N-based biomass porous carbon composite(Fe/N-p Carbon) was prepared by a facile high-temperature carbonization method from biomass,and the effect of Fe/N-p Carbon on the thermal decomposition of energetic molecular perovskite-based material DAP-4 was *** porous carbonaceous materials was considered as the micro/nano support layers for in situ deposition of Fe/N ***/Np Carbon was prepared simply by the high-temperature carbonization *** was found that it showed the inherent catalysis properties for thermal decomposition of *** heat release of DAP-4/Fe/N-p Carbon by DSC curves tested had increased slightly,compared from DAP-4/Fe/N-p *** decomposition temperature peak of DAP-4 at the presence of Fe/N-p Carbon had reduced by 79°C from384.4°C(pure DAP-4) to 305.4°C(DAP-4/Fe/N-p Carbon-3).The apparent activation energy of DAP-4thermal decomposition also had decreased by 29.1 J/*** possible catalytic decomposition mechanism of DAP-4 with Fe/N-p Carbon was proposed.

关键词： Biomass materials Porous carbon DAP-4 Thermal decomposition Facile method

Computational fluid dynamics simulation and experimental study on mixing performance of a three-dimensional circular cyclone-type microreactor

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Chinese Chemical Letters 2024年第4期35卷 382-388页

作者： Shiyu Hou Maolin Sun Liming cao Chaoming Liang Jiaxin Yang Xinggui zhou Jinxing Ye Ruihua Cheng School of Chemical Engineering East China University of Science and TechnologyShanghai 200237China School of Biomedical and Pharmaceutical Sciences Guangdong University of TechnologyGuangzhou 510006China School of Pharmacy East China University of Science and TechnologyShanghai 200237China

Microchannels enable the fast and efficient mixing of multiphase *** this study, a millimeter-scale three-dimensional(3D) circular cyclone-type microreactor was designed for the *** flow characteristics and mixing intensity were simulated by computational fluid dynamics simulations at a flow rate range of 12–96 m L/min using a water/ethyl acetate *** the 3D variable-diameter structure,the microreactor induced paired opposite vortices and abruptly changed the local pressure to achieve a stable turbulent effect within the theoretical range of laminar *** injection simulations indicated that sufficient mixing units successfully promote fluid ***-coupling experiments showed a segregation index of X_S= 0.00,039 within a residence time of 9 *** experiments on the nbutanol/succinic acid/water system showed that the 3D circular cyclone-type microreactor achieved 100%extraction efficiency(E) in 4.25 s, and the overall volume mass transfer coefficient(K_La) reached 0.05–1.5s^(-1) in 12–96 m L/*** isolated yield of the phase transfer alkylation and oxidation reactions in the 3D circular cyclone-type microreactor achieved 99% within 36 s, which was superior to the coil microreactor and batch reactor.

关键词： Microfluidics Passive microreactor CFD simulation Extraction Liquid-liquid biphase reaction

Service Function Chain Migration in LEO Satellite Networks

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China Communications 2024年第3期21卷 247-259页

作者： Geng Yuhui Wang Niwei Chen Xi Xu Xiaofan zhou Changsheng Yang Junyi Xiao Zhenyu cao Xianbin School of Electronic and Information Engineering Beihang UniversityBeijing 100191China Key Laboratory of Advanced Technology of Near Space Information System Ministry of Industry and Information Technology of ChinaBeijing 100191China Shanghai Key Laboratory of Satellite Network Shanghai 201204China Shanghai Satellite Network Research Institute Co. Ltd.Shanghai 201204China

With the advancements of software defined network(SDN)and network function virtualization(NFV),service function chain(SFC)placement becomes a crucial enabler for flexible resource scheduling in low earth orbit(LEO)satellite *** due to the scarcity of bandwidth resources and dynamic topology of LEO satellites,the static SFC placement schemes may cause performance degradation,resource waste and even service *** this paper,we consider migration and establish an online migration model,especially considering the dynamic *** the scarcity of bandwidth resources,the model aims to maximize the total number of accepted SFCs while incurring as little bandwidth cost of SFC transmission and migration as *** to its NP-hardness,we propose a heuristic minimized dynamic SFC migration(MDSM)algorithm that only triggers the migration procedure when new SFCs are *** results demonstrate that MDSM achieves a performance close to the upper bound with lower complexity.

关键词： network function virtualization(NFV) resource allocation satellite networks service function chain(SFC) SFC migration SFC placement soft-ware defined network(SDN)

The Burden of Hypertension-Related Chronic Kidney Disease—China,2010–2019

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China CDC weekly 2024年第14期6卷 282-288页

作者： Youyuan Bu Yueru Liu Maigeng zhou peng Yin Kejun Liu Yamin Bai Xuancheng Lu Chinese Center for Disease Control and Prevention BeijingChina National Center for Chronic and Non-Communicable Disease Control and Prevention Chinese Center For Disease Control and PreventionBeijingChina China National Health Development Research Center BeijingChina

What is already known about this topic?The global burden of chronic kidney disease(CKD)is on the *** is added by this report?In 2019,5.58 million individuals in China were affected by CKD related to hypertension,leading to 70,260 fatalities and 1.69 million disability-adjusted life years(DALYs).The most affected groups were men,older individuals,and residents of western *** the period from 2010–2019,the age-standardized prevalence rate(ASPR)remained constant,and the agestandardized mortality rate(ASMR)and agestandardized DALY rate(ASDR)showed a decreasing ***,there was an increase in the number of cases,deaths,and DALYs associated with this *** are the implications for public health practice?Hypertension significantly contributes to the burden of CKD;therefore,raising awareness and implementing early screening measures are essential.

关键词： Kidney mortality burden

Multiple damage zones around hydraulic fractures generated by high-frequency pulsating hydraulic fracturing

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Petroleum Science 2024年第4期21卷 2688-2702页

作者： Yan peng Sheng-Jie Wei Guang-Qing Zhang Da-Wei zhou Chuang-Chao Xu School of Petroleum Engineering China University of Petroleum PetroChina Changqing Oilfield Company

Pulsating hydraulic fracturing(PHF) is a promising fracturing method and can generate a dynamic periodic pressure. The periodic pressure can induce fatigue failure of rocks and decrease initiation pressure of fracture. If the frequency of periodic pressure exceeds 10 Hz, the distribution of pressure along the main fracture will be heterogeneous, which is much different from the one induced by the common fracturing method. In this study, the impact of this special spatial feature of pressure on hydraulic fracture is mainly investigated. A coupled numerical simulation model is first proposed and verified through experimental and theoretical solutions. The mechanism of secondary fracture initiation around the main fracture is then discovered. In addition, sensitivity studies are conducted to find out the application potential of this new method. The results show that(1) this coupled numerical simulation model is accurate. Through comparison with experimental and theoretical data, the average error of this coupled model is less than 1.01%.(2) Even if a reservoir has no natural fracture, this heterogeneous distribution pressure can also cause many secondary fractures around the main fracture.(3) The mechanism of secondary fracture initiation is that this heterogeneous distribution pressure causes tensile stress at many locations along the main fracture.(4) Through adjusting the stimulation parameters, the stimulation efficiency can be improved. The average and amplitude of pressure can increase possibility of secondary fracture initiation. The frequency of this periodic pressure can increase number of secondary fractures. Even 6 secondary fractures along a 100 m-length main fracture can be generated.(5) The influence magnitudes of stimulation parameters are larger than ones of geomechanical properties, therefore, this new fracturing method has a wide application potential.

关键词： Tight reservoir Reservoir stimulation Numerical simulation Secondary fracture Fracture initiation

Nickel-modified In_(2)O_(3) with inherent oxygen vacancies for CO_(2) hydrogenation to methanol

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Science China Chemistry 2024年第5期67卷 1715-1728页

作者： Zixuan zhou Yuchen Wang Yuanjie Bao Haiyan Yang Jiong Li Chunran Chang Shenggang Li peng Gao CAS Key Laboratory of Low-Carbon Conversion Science and Engineering Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201210China University of Chinese Academy of Sciences Beijing 100049China School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China Shaanxi Key Laboratory of Low Metamorphic Coal Clean Utilization School of Chemistry and Chemical EngineeringYulin UniversityYulin 719000China

Methanol synthesis is one of the most important industrially-viable approaches for carbon dioxide(CO_(2)) utilization, as the produced methanol can be used as a platform chemical for manufacturing green fuels and chemicals. The In_(2)O_(3) catalysts are ideal for sustainable methanol synthesis and have received considerable attention. Herein, Co-, Ni-and Cu-modified In_(2)O_(3) catalysts were fabricated with high dispersion and high stability to improve the hydrogenation performance. The Ni-promoted In_(2)O_(3) catalyst in the form of high dispersion possessed the largest amount of oxygen vacancies and the strongest ability for H_(2) activation, leading to the highest CO_(2) conversion and space time yield of methanol of 0.390 g_(Me OH)g_(cat)^(-1)h^(-1) with CH_(3)OH selectivity of 68.7%. In addition, the catalyst exhibits very stable performance over 120 h on stream, which suggests the promising prospect for industrial applications. Further experimental and theoretical studies demonstrate that surface Ni doping promotes the formation of oxygen defects on the In_(2)O_(3) catalyst, although it also results in lower methanol selectivity. Surprisingly, subsurface Ni dopants are found to be more beneficial for methanol formation than surface Ni dopants, so the Nipromoted In_(2)O_(3)catalyst with a lower surface Ni content at the similar Ni loading can reach higher methanol selectivity and productivity. This work thus provides theoretical guidance for significantly improving the CO_(2) reactivity of In_(2)O_(3)-based catalysts while maintaining high methanol selectivity.

关键词： carbon dioxide hydrogenation methanol synthesis indium oxides Ni doping sites transition metal promoters

Universal paradigm of ternary metacomposites with tunable epsilon-negative and epsilon-near-zero response for perfect electromagnetic shielding

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Rare Metals 2024年第2期43卷 796-809页

作者： Yun-peng Qu Yun-Lei zhou Yang Luo Yao Liu Jun-Fei Ding Yan-Li Chen Xiu Gong Jing-Liang Yang Qiong peng Xiao-Si Qi College of Physics Guizhou UniversityGuiyang550025China Hangzhou Institute of Technology Xidian UniversityHangzhou311231China Department of Materials ETH Zurich8093ZurichSwitzerland Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong UniversityJinan250061China

CaCu_(3)Ti_(4)O_(12)(CCTO)ceramic nanocomposites incorporating graphene–carbon black(GRCB)fillers were fabricated by spark plasma sintering *** percolative effects of conductive GRCB fillers on dielectric response of GRCB/CCTO ternary metacomposites were systematically *** weakly real permittivity(ε′)-negative response(ε′~−1×10^(2))was achieved which originated from weakly low-frequency plasmonic state of free carriers within constructed GRCB *** enhancing three-dimensional GRCB network,the plasma frequency of metacomposites increased while the damping factor ***,theε′-negative values of metacomposites were tuned from−10^(2) to−10^(4) orders of magnitude andε′-near-zero(ENZ)frequencies from~142 to~340 MHz which substantially benefited from the moderate carrier concentration of GRCB dual *** Drude model and equivalent circuit models were adopted to demonstrate dielectric and electrical *** obtained metacomposites show strong EM shielding effect along with enhanced plasmonic oscillation and even better achieving perfect EM shielding effect in ENZ *** work achieves the tunableε′-negative andε′-near-zero response and more importantly clarifies its regulation mechanism in ceramic-based ternary metacomposites,which opens up the possibility of designing high-performance EM shielding materials based on metacomposites.

关键词： Metacomposites Ceramic matrix composites Negative permittivity Epsilon-near-zero Electromagnetic shielding

Effect of the extrahepatic bile duct anatomy on choledocholithiasis and its clinical significance

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World Journal of Gastrointestinal Surgery 2024年第5期16卷 1363-1370页

作者： Zheng cao Jia zhou Li Wei Hai-Yu He Jun Li Department of Gastroenterology The Second Affiliated Hospital of Kunming Medical UniversityKunming 650000Yunnan ProvinceChina

BACKGROUND A comprehensive understanding of the extrahepatic bile duct anatomy is vital to guide surgical procedures and perform endoscopic retrograde *** irregularities within the extrahepatic bile duct may increase susceptibility to bile duct *** To investigate the anatomical risk factors associated with extrahepatic bile ducts in patients diagnosed with choledocholithiasis,with a specific focus on preventing stone recurrence after surgical intervention and endoscopic *** We retrospectively analyzed the medical records of 124 patients without choledocholithiasis and 108 with confirmed choledocholithiasis who underwent magnetic resonance cholangiopancreatography examinations at our center between January 2022 and October *** regression analyses were conducted to identify the anatomical risk factors influencing the incidence of common bile duct *** Multivariate logistic regression analysis revealed that several factors independently contributed to choledocholithiasis *** independent risk factors for choledocholithiasis were diameter of the common hepatic[adjusted odds ratio(aOR)=1.43,95%confidence interval(CI):1.07-1.92,adjusted P value=0.016]and common bile(aOR=1.68,95%CI:1.27-2.23,adjusted P value<0.001)ducts,length of the common hepatic duct(aOR=0.92,95%CI:0.84-0.99,adjusted P value=0.034),and angle of the common bile duct(aOR=0.92,95%CI:0.89–0.95,adjusted P value<0.001).The anatomical features of the extrahepatic bile duct were directly associated with choledocholithiasis *** risk factors include an enlarged diameter of the common hepatic and bile ducts,a shorter length of the common hepatic duct,and a reduced angle of the common bile duct.

关键词： Bile ducts Extrahepatic Choledocholithiasis Cholangiopancreatography Magnetic resonance Cholangiopancreatography Endoscopic retrograde

Fault Diagnosis for Railway Point Machines Using VMD Multi-scale Permutation Entropy and ReliefF Based on Vibration Signals

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Chinese Journal of Electronics 2024年

作者： Yongkui SUN Yuan cao peng LI Shuai SU National Engineering Research Center of Rail Transportation Operation and Control System Beijing Jiaotong University School of Automation and Intelligence Beijing Jiaotong University Frontiers Science Center for Smart High-speed Railway System Beijing Jiaotong University

The railway point machine plays an important part in railway systems. It is closely related to the safe operation of trains. Considering the advantages of vibration signals on anti-interference, this paper develops a novel vibration signal-based diagnosis approach for railway point machines. First, variational mode decomposition(VMD)is adopted for data preprocessing, which is verified more effective than empirical mode decomposition. Next, multiscale permutation entropy is extracted to characterize the fault features from multiple scales. Then ReliefF is utilized for feature selection, which can greatly decrease the feature dimension and improve the diagnosis accuracy. By experiment comparisons, the proposed approach performs best on diagnosis for railway point machines. The diagnosis accuracies on reverse-normal and normal-reverse processes are respectively 100% and 98.29%.

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