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Effects of aggregate size distribution and carbon nanotubes on the mechanical properties of cemented gangue backfill samples under true triaxial compression

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 311-324页

作者： Qian Yin fan Wen Zhigang Tao Hai Pu Tianci Deng Yaoyao meng Qingbin meng Hongwen Jing Bo meng Jiangyu Wu State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines Anhui University of Science and TechnologyHuainan 232001China State Key Laboratory for Geomechanics&Deep Underground Engineering China University of Mining and Technology(Beijing)Beijing 100083China Key Laboratory of Xinjiang Coal Resources Green Mining Ministry of EducationXinjiang Institute of EngineeringUrumqi 830023China

The mechanical behavior of cemented gangue backfill materials(CGBMs)is closely related to particle size distribution(PSD)of aggregates and properties of cementitious ***,the true triaxial compression tests,CT scanning,SEM,and EDS tests were conducted on cemented gangue backfill samples(CGBSs)with various carbon nanotube concentrations(P_(CNT))that satisfied fractal theory for the PSD of *** mechanical properties,energy dissipations,and failure mechanisms of the CGBSs under true triaxial compression were systematically *** results indicate that appropriate carbon nanotubes(CNTs)effectively enhance the mechanical properties and energy dissipations of CGBSs through micropore filling and microcrack bridging,and the optimal effect appears at P_(CNT)of 0.08wt%.Taking PSD fractal dimension(D)of 2.500 as an example,compared to that of CGBS without CNT,the peak strength(σ_(p)),axial peak strain(ε_(1,p)),elastic strain energy(Ue),and dissipated energy(U_(d))increased by 12.76%,29.60%,19.05%,and90.39%,***,excessive CNTs can reduce the mechanical properties of CGBSs due to CNT agglomeration,manifesting a decrease inρ_(p),ε_(1,p),and the volumetric strain increment(Δε_(v))when P_(CNT)increases from 0.08wt%to 0.12wt%.Moreover,the addition of CNTs improved the integrity of CGBS after macroscopic failure,and crack extension in CGBSs appeared in two modes:detour and pass through the ***σ_(p)and U_(d)firstly increase and then decrease with increasing D,and porosity shows the opposite ***ε_(1,p)andΔε_(v)are negatively correlated with D,and CGBS with D=2.150 has the maximum deformation parameters(ε_(1,p)=0.05079,Δε_(v)=0.01990)due to the frictional slip effect caused by coarse *** increasing D,the failure modes of CGBSs are sequentially manifested as oblique shear failure,"Y-shaped"shear failure,and conjugate shear failure.

关键词： cemented gangue backfill materials particle size distribution true triaxial compression test carbon nanotubes mechanical properties failure modes

De novo synthesis of atropisomeric benzofurans via Cu/SPDO complex catalyzed asymmetric formal [3 + 2] annulation

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Science China Chemistry 2025年第1期68卷 174-180页

作者： fan-Xiao meng Xing-Yu Wang Ka Lu Ju-Song Yang Fu-Min Zhang Ai-Jun Ma Bao Du Yong-Qiang Tu State Key Laboratory of Applied Organic Chemistry College of Chemistry and Chemical Engineering Lanzhou University School of Chemistry and Chemical Engineering Shanghai Jiao Tong University School of Biotechnology and Health Sciences Wuyi University

Herein, the de novo synthesis of atropisomeric benzofurans through the Cu/spirocyclic-pyrrolidine-oxazoline(SPDO) complex catalyze asymmetric formal [3 + 2] cycloaddition between quinones and ynamides is explored, producing a range of structurally diverse axially chiral benzofurans in satisfactory yields with good to excellent enantioselectivities. Furthermore, density functional theory calculations were applied to explain the possible reaction mechanism.

关键词： benzofuran atropisomers novel de novo synthetic strategy asymmetric formal [3 + 2] cycladdition Cu/SPDO complex DFT calculations

Deep Synchronization Control of Grid-Forming Converters:A Reinforcement Learning Approach

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IEEE/CAA Journal of Automatica Sinica 2025年第1期 273-275页

作者： Zhuorui Wu meng Zhang Bo fan Yang Shi Xiaohong Guan the School of Cyber Science and Engineering Xi'an Jiaotong University the Department of Mechanical Engineering University of Victoria

Dear Editor,This letter proposes a deep synchronization control(DSC) method to synchronize grid-forming converters with power grids. The method involves constructing a novel controller for grid-forming converters based on the stable deep dynamics model. To enhance the performance of the controller, the dynamics model is optimized within the deep reinforcement learning(DRL) framework. Simulation results verify that the proposed method can reduce frequency deviation and improve active power responses.

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Certain Cuntz Semigroup Properties of Certain Crossed Product C^*-algebras

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Acta Mathematica Sinica,English Series 2020年第3期36卷 337-362页

作者： Qing zhai fan Department of Mathematics Shanghai Maritime UniversityShanghai 201306P.R.C hina

We show that the following properties of the C^*-algebras in a class Ω are inherited by simple unital C-algebras in the class TAΩ:(1)(m,n)-decomposable,(2) weakly(m,n)-divisible,(3) weak Riesz *** an application,let A be an infinite dimensional simple unital C-algebra such that A has one of the above-listed *** that α:G→Aut(A) is an action of a finite group G on A which has the tracial Rokhlin *** the crossed product C^*-algebra C^*(G,A,α) also has the property under consideration.

关键词： C^*-algebras tracial approximation Cuntz semigroup

Thermally Conductive Polyimide/Boron Nitride Composite Films with Improved Interfacial Compatibility Based on Modified Fillers by Polyimide Brushes

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Chinese Journal of Polymer Science 2023年第12期41卷 1921-1936,I0009页

作者： meng-Yan Gao Lei zhai Song Mo Yan Jia Yi Liu Min-Hui He Lin fan Key Laboratory of Science and Technology on High-tech Polymer Materials Institute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China

Polyimide-based composite films with high thermal conductivity,good mechanical property and electrical insulating performance are urgently needed in the electronics and microelectronics *** one of the key technical challenges to be solved,interfacial compatibility between filler and matrix plays an important role for composite ***,boron nitride was modified by grafting polyimide brushes via a twostep method,and a series of thermally conductive polyimide/boron nitride composite films were *** characterization and performance results proved that the interfacial interaction and compatibility was greatly enhanced,resulting in a significant reduction in defects and interfacial thermal *** interphase width of transition zone between two phases was also efficiently enlarged due to polyimide brushes grafted on filler *** a result,composite films based on polyimide-grafted boron nitride exhibited significantly improved properties compared with those based on pristine *** strength can reach up to 80 MPa even if the filler content is as high as 50 wt%.The out-of-plane and in-plane thermal conductivity of composite film increased to 0.841 and 0.850 W·m^(-1)·K^(-1),*** addition,thermal and dielectric properties of composite films were also enhanced to some *** above results indicate that surface modification by chemically grafting polymer brushes is an effective method to improve two-phase interfacial compatibility so as to prepare composite film with enhanced properties.

关键词： Polyimide Composite film Boron nitride Thermal conductivity Interfacial compatibility

Catalytic spectrophotometric determination of trace selenium in microemulsion after separation and enrichment by SDG

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Rare Metals 2006年第3期25卷 281-286页

作者： LI Huizhi zhai Diantang fan Yingju School of Chemistry and Chemical Engineering Jinan University Jinan 250022 China

A new catalytic spectrophotometric method was developed for the determination of trace amount of Se（Ⅳ） in microemulsion medium. The method is based on the catalytic effect of traces of Se（Ⅳ） on the oxidation of 2＇,4＇-dichlorophenylfluomne （p-CPF） by potassium bromate with HNO3 as an activator in the presence of nonionic microemulsion medium. Under optimum conditions, the calibration graph is linear in the range of 0.4-15 μg·L^-1 of Se（Ⅳ） at 480 nm. The detection limit achieved is 9.86 × 10^-10μg·L^-1. Samples were dissolved and the obtained trace Se（Ⅳ） was separated and enriched by sulphydryl dextrane gel （SDG）. The method has been applied for determination of trace selenium with satisfactory results.

关键词： analytical chemistry Se(Ⅳ) catalytic spectrophotometric microemulsion medium separation enrichment

Achieving Paris Agreement temperature goals requires carbon neutrality by middle century with far-reaching transitions in the whole society

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Advances in Climate Change Research 2021年第2期12卷 281-286页

作者： HUANG meng-Tian zhai Pan-Mao State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing100081China

The concept of carbon neutrality is much emphasized in IPCC Spatial Report on Global Warming of 1.5C in order to achieve the long-termtemperature goals as reflected in Paris *** keep these goals within reach,peaking the global carbon emissions as soon as possible andachieving carbon neutrality are urgently ***,global CO_(2)emissions continued to grow up to a record high of 43.1 Gt CO_(2)during2019,with fossil CO_(2)emissions of 36.5 Gt CO_(2)and land-use change emissions of 6.6 Gt CO_(2).In such case,the global carbon emissions mustdrop 32 Gt CO_(2)(7.6%per year)from 2020 to 2030 for the 1.5C warming limit,which is even larger than the COVID-induced reduction(6.4%)in global CO_(2)emissions during ***,China has announced scaling up its national commitments,aiming to peak its CO_(2)emissionsbefore 2030 and achieve carbon neutrality before *** these goals requires rapid and far-reaching transitions in the whole *** one hand,deeper emissions reduction in all sectors includes decarbonization of energy,electrification,increasing share of renewables,energyefficiency,sustainable land management,decarbonization of transport,reducing food loss and waste,as well as behavior and lifestyles *** the other hand,possible actions by removing CO_(2)from the atmosphere involves enlarging land and ocean net carbon sink,CO_(2)removaltechnologies(such as Bioenergy with carbon capture and storage),and CO_(2)capture,utilization and storage technologies,but should be cautionfor their scales and tradeoffs.

关键词： Carbon neutrality Carbon emissions peak Climate change Paris agreement Green recovery COVID-19 pandemic

Comparison Properties for Asymptotically Tracially Approximation C^(*)-algebras

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Acta Mathematica Sinica,English Series 2023年第5期39卷 863-884页

作者： Qing zhai fan Xiao Chun fanG College of Education Shanghai Jian Qiao UniversityShanghai 201306P.R.China Department of Mathematics Shanghai Maritime UniversityShanghai 201306P.R.China Department of Mathematics Tongji UniversityShanghai 200092P.R.China

We show that the following properties of the C*-algebras in a class P are inherited by simple unital C*-algebras in the class of asymptotically tracially in P :(1) n-comparison,(2) α-comparison(1 ≤ α < ∞).

关键词： C*-algebras asymptotically tracially approximation Cuntz semigroup

Effect of Aggregation Structure on Thermal Expansion Behavior of Polyimide Films with Different Thickness

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Chinese Journal of Polymer Science 2022年第12期40卷 1651-1661,I0010页

作者： Chang-Ou Wang Lei zhai Song Mo Yi Liu meng-Yan Gao Yan Jia Min-Hui He Lin fan Key Laboratory of Science and Technology on High-tech Polymer Materials Institute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China

Polyimide films derived from representative PMDA/ODA were prepared with thickness ranging from 5 μm to 25 μm,and the effect of aggregation structure on thermal expansion behavior along different directions was *** in-plane and out-of-plane linear thermal expansion(CTEand CTE) were respectively characterized by thermal mechanical analysis and FT-near-IR interference *** and anisotropic behavior of thermal expan sion were also *** increasing film thickness,CTEgradually increased from 32.2 ppm/℃ to46.1 ppm/℃ while CTEdecreased from 149.7 ppm/℃ to 128.2 ppm/℃.Volumetric thermal expansion of polyimide films was less sensitive to the va ried thickness,but anisotropy of thermal expansion was *** film of 5 μm thickness showed large birefringence,indicating more considerable in-plane chain orientation ***,molecular chains were more densely packed along in-plane direction when film thickness increased,while became loosely stacked in the out-of-plane *** contrast to the enhanced lateral chain packing for thicker film s,higher vertical chain packing order was found in thinner *** variation of aggregation structure during thermal expansion procedure was analyzed by temperature-dependent *** is proved that thermal expansion behavior of thinner films could be largely attributed to molecular chain packing,whereas that may be influenced by many factors for thicker films in addition to the effect of chain *** results revealed that thermal expansion of films with thickness variation is closely related to molecular chain orientation and packing,which is associated with both chemistry and morphological structure of polyimide.

关键词： Polyimide film Thermal expansion behavior Aggregation structure Molecular chain packing Thickness variation