期刊文献+
共找到207篇文章
< 1 2 11 >
每页显示 20 50 100
Strong electronic metal-support interactions for enhanced hydroformylation activity and stability over Rh single-atom catalysts through phosphorus doping
1
作者 Boyang Fu Ping Ma +11 位作者 Xiaoyang Ding Kaifu Cai Limin Sun Yujin Zhu Qiwei Yin Yihao Sun Tianle Liu Yuzhen Li Yuxing Xu Jian Gu Haowen Ma Junling Lu 《中国科学技术大学学报》 北大核心 2025年第3期2-10,1,I0001,共11页
By simplifying catalyst-product separation and reducing phosphorus waste,heterogeneous hydroformylation offers a more sustainable alternative to homogeneous processes.However,heterogeneous hydroformylation catalysts d... By simplifying catalyst-product separation and reducing phosphorus waste,heterogeneous hydroformylation offers a more sustainable alternative to homogeneous processes.However,heterogeneous hydroformylation catalysts developed thus far still suffer from the issues of much lower activity and metal leaching,which severely hinder their practical application.Here,we demonstrate that incorporating phosphorus(P)atoms into graphitic carbon nitride(PCN)supports facilitates charge transfer from Rh to the PCN support,thus largely enhancing electronic metal-support interactions(EMSIs).In the styrene hydroformylation reaction,the activity of Rh_(1)/PCN single-atom catalysts(SACs)with varying P contents exhibited a volcano-shaped relationship with P doping,where the Rh_(1)/PCN SAC with optimal P doping showed exceptional activity,approximately 5.8-and 3.3-fold greater than that of the Rh_(1)/g-C_(3)N_(4)SAC without P doping and the industrial homogeneous catalyst HRh(CO)(PPh_(3))_(3),respectively.In addition,the optimal Rh_(1)/PCN SAC catalyst also demonstrated largely enhanced multicycle stability without any visible metal aggregation owing to the increased EMSIs,which sharply differed from the severe metal aggregation of large nanoparticles on the Rh_(1)/g-C_(3)N_(4)SAC.Mechan-istic studies revealed that the enhanced catalytic performance could be attributed to electron-deficient Rh species,which reduced CO adsorption while simultaneously promoting alkene adsorption through increased EMSIs.These findings suggest that tuning EMSIs is an effective way to achieve SACs with high activity and durability. 展开更多
关键词 heterogeneous hydroformylation Rh single-atom catalysts electronic metal-support interactions phosphorus doping
在线阅读 下载PDF
Research progress on metal-support interactions over Ni-based catalysts for CH_(4)-CO_(2)reforming reaction
2
作者 SUN Kai JIANG Jianfei +4 位作者 LIU Zixuan GENG Shiqi LIU Zhenmin YANG Jiaqian LI Shasha 《燃料化学学报(中英文)》 北大核心 2025年第4期434-451,共18页
With ongoing global warming and increasing energy demands,the CH_(4)-CO_(2)reforming reaction(dry reforming of methane,DRM)has garnered significant attention as a promising carbon capture and utilization technology.Ni... With ongoing global warming and increasing energy demands,the CH_(4)-CO_(2)reforming reaction(dry reforming of methane,DRM)has garnered significant attention as a promising carbon capture and utilization technology.Nickel-based catalysts are renowned for their outstanding activity and selectivity in this process.The impact of metal-support interaction(MSI),on Ni-based catalyst performance has been extensively researched and debated recently.This paper reviews the recent research progress of MSI on Ni-based catalysts and their characterization and modulation strategies in catalytic reactions.From the perspective of MSI,the effects of different carriers(metal oxides,carbon materials and molecular sieves,etc.)are introduced on the dispersion and surface structure of Ni active metal particles,and the effect of MSI on the activity and stability of DRM reactions on Ni-based catalysts is discussed in detail.Future research should focus on better understanding and controlling MSI to improve the performance and durability of nickel-based catalysts in CH_(4)-CO_(2)reforming,advancing cleaner energy technologies. 展开更多
关键词 CO_(2)utilization CH_(4)-CO_(2)reforming Ni-based catalysts metal-support interactions supports
在线阅读 下载PDF
Remote electron effects and π-π interactions of α-diimine nickel complexes
3
作者 Yizhan Wang Hailong He Dan Peng 《中国科学技术大学学报》 CAS CSCD 北大核心 2024年第9期17-22,68,共7页
The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nick... The seminal report ofα-diimine palladium and nickel catalysts in 1995 represented a major breakthrough in the preparation of functionalized polyolefin materials.Owing to the high abundance and low cost of nickel,nickel-based catalysts have great application prospects in the industrialization process of olefin coordination polymerization.In this work,various N-aryl substituents with different electronic effects were synthesized and introduced intoα-diimine ligands.The aspreparedα-diimine nickel catalysts showed high polymerization activity(0.9×10^(7)–3.0×10^(7)g·mol^(−1)·h^(−1))in ethylene polymerization,generating polyethylene products with adjustable molecular weights(Mn values:7.4×10^(4)–146.9×10^(4)g·mol^(−1))and branching densities(31/1000 C–68/1000 C).The resulting polyethylene products showed excellent mechanical properties,with high tensile strength(up to 25.0 MPa)and high strain at break values(up to 3890%).The copolymerization of ethylene and polar monomers can also be achieved by these nicekel complexes,ultimately preparing functionalized polyolefins. 展开更多
关键词 α-diimine nickel catalyst ethylene polymerization π-πinteraction effect electronic effect polar monomer
在线阅读 下载PDF
Symmetry breaking of photonic spin-orbit interactions in metasurfaces 被引量:14
4
作者 Fei Zhang Mingbo Pu +2 位作者 Jun Luo Honglin Yu Xiangang Luo 《光电工程》 CAS CSCD 北大核心 2017年第3期319-325,共7页
Spin-orbit optical phenomena pertain to the wider class of electromagnetic effects originating from the interaction of the photon spin with the spatial structure and propagation characteristics of an optical wave,medi... Spin-orbit optical phenomena pertain to the wider class of electromagnetic effects originating from the interaction of the photon spin with the spatial structure and propagation characteristics of an optical wave,mediated by suitable optical media.There are many emerging photonic applications of spin-orbit interactions(SOI)of light,such as control of the optical wave propagation via the spin,enhanced optical manipulation,and generation of structured optical fields.Unfortunately,current applications are based on symmetric SOI,that is,the behaviours of polarized photons with two opposite spins are opposite,leading to the limit of spin-based multiplexers.The symmetry of SOI can be broken in our proposed metasurfaces,consisting of spatially varying birefringence,which can arbitrarily and independently build SOI for two opposite spins without reduction of optical energy usage.We obtain three kinds of dual-functional metasurfaces at visible and infrared wavelengths with high efficiency.Our concept of generation of asymmetric SOI for two spins,using anisotropic metasurfaces,will open new degrees of freedoms for building new types of spin-controlled multifunctional shared-aperture devices for the generation of complex structured optical fields. 展开更多
关键词 metasurfaces METAMATERIALS spin-orbit interactions
在线阅读 下载PDF
Graph-based method for human-object interactions detection 被引量:1
5
作者 XIA Li-min WU Wei 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第1期205-218,共14页
Human-object interaction(HOIs)detection is a new branch of visual relationship detection,which plays an important role in the field of image understanding.Because of the complexity and diversity of image content,the d... Human-object interaction(HOIs)detection is a new branch of visual relationship detection,which plays an important role in the field of image understanding.Because of the complexity and diversity of image content,the detection of HOIs is still an onerous challenge.Unlike most of the current works for HOIs detection which only rely on the pairwise information of a human and an object,we propose a graph-based HOIs detection method that models context and global structure information.Firstly,to better utilize the relations between humans and objects,the detected humans and objects are regarded as nodes to construct a fully connected undirected graph,and the graph is pruned to obtain an HOI graph that only preserving the edges connecting human and object nodes.Then,in order to obtain more robust features of human and object nodes,two different attention-based feature extraction networks are proposed,which model global and local contexts respectively.Finally,the graph attention network is introduced to pass messages between different nodes in the HOI graph iteratively,and detect the potential HOIs.Experiments on V-COCO and HICO-DET datasets verify the effectiveness of the proposed method,and show that it is superior to many existing methods. 展开更多
关键词 human-object interactions visual relationship context information graph attention network
在线阅读 下载PDF
Clay-Microbe Interactions and Implication for Remediation of Inorganic Contaminants
6
作者 DONG Hailiang 《矿物学报》 CAS CSCD 北大核心 2013年第S1期18-18,共1页
Mineral–microbe interactions indirectly affect the geochemical fluxes and biogeochemical cycling of a large number of elements. Among them are toxic heavy metals (e.g. chromium), radionuclides (uranium and technetium... Mineral–microbe interactions indirectly affect the geochemical fluxes and biogeochemical cycling of a large number of elements. Among them are toxic heavy metals (e.g. chromium), radionuclides (uranium and technetium), and nitrogen. Heavy metals and radionuclides enter the environment from various sources such as mining activity, nuclear weapons production, metallurgical and chemical industries. Other metals, such as lead, arsenic, antimony, and cadmium, are enriched in certain environments by either natural or anthropogenic processes. Because many of these metals and radionuclides are carcinogens, their release into the environment and their fate cause intense scientific and public concern and are the subject of substantial research. Nitrate enters the environment largely through agricultural activity. Human health risks from nitrate uptake from drinking water supplies run the gamut from increased cancer risk to birth defects. 展开更多
关键词 clay-microbe interactions INORGANIC CONTAMINANTS clay-associated Fe(Ⅱ)
在线阅读 下载PDF
Weights of Different Multipole Interactions in Low Temperature Fast Reactions
7
作者 Tan Xiaofeng Dong Feng Li XuechuState key laboratory of molecular dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, PRC 《原子与分子物理学报》 CAS CSCD 北大核心 1998年第S1期179-180,共2页
Studiesofdiatomdiatomfastreactionplayaveryimportantroleinunderstandingthenatureofchemicalreactions.Itisalsoa... Studiesofdiatomdiatomfastreactionplayaveryimportantroleinunderstandingthenatureofchemicalreactions.Itisalsoaveryactivefieldt... 展开更多
关键词 interactions LOW WEIGHTS DIFFERENT
在线阅读 下载PDF
Proteomic study of three component interactions: plant, pathogens and antagonistic fungi
8
作者 Marra R Ambrosino P +9 位作者 Scala V Romano C Vinale F Ferraioli S Ruocco M Carbone V Woo S L Turrà D Scala F Lorito M 《浙江大学学报(农业与生命科学版)》 CAS CSCD 北大核心 2004年第4期449-449,共1页
The molecular factors involved in the three-way interaction between plant, pathogenic fungi and antagonistic/biocontrol fungi, such as Trichoderma, are still poorly understood, even if they represent a matter of inter... The molecular factors involved in the three-way interaction between plant, pathogenic fungi and antagonistic/biocontrol fungi, such as Trichoderma, are still poorly understood, even if they represent a matter of interest for improving crop management and developing new strategies for plant diseases control. The aim of this work is to investigate the components involved in this interaction and, for this purpose, a proteomic approach was used. 2-D maps of the protein extracts from the single components in various interactions between plants (potato, bean, tobacco or tomato), pathogens (Botrytis cinerea, Rhizoctonia solani or Pythium ultimum) and biocontrol fungi (Trichoderma atroviride strain P1 or Trichoderma harzianum strain T22) were obtained. The proteome of each partner was collected separately and extracted by acetone precipitation in presence of trichloroacetic acid and a reducing agent (DTT). The extracted proteins were separated by isoelectrofocusing (IEF), using IPG (Immobilized pH gradient) strips, followed by SDS-PAGE. In order to improve resolution the separations were performed both on wide than narrow pH range and on different gel lengths. Differential spots were noted in the proteome of the three-way interaction when compared to each single component. These were further characterized by mass spectrometry and in silico analysis with the aim of identifying and cloning the relative genes. During the in vitro interaction of T. harzianum strain T22 with tomato and the culture filtrate or cell walls of pathogens, the spot number was higher than in the presence of pathogen biomass. In terms of Trichoderma differential proteins displayed on 2D gels, the most important changes were obtained in the presence of P. ultimum . During the in vivo interaction with tomato, the antagonist proteome changed much more in presence of soilborne fungi R. solani and P. ultimum than with the foliar fungus B. cinerea, both in terms of total and increased or novel spots. In silico analysis of some of those spots revealed homology with intracellular enzymes (GTPases, hydrolases) and with stress-related proteins (heat shock proteins HSP70, bacteriocin cloacin). Specific proteins in the plant proteome, i.e. pathogenesis-related proteins, have been identified during the in vivo interaction of bean with R. solani and T. atroviride strain P1. This is in agreement with the demonstrated ability of these beneficial fungi to induce plant systemic disease resistance by activating expression of defence-related genes. Proteins extracted from T. atrovride strain P1 which were analysed by mass spectrometry, revealed some interesting homologies with a fungal hydrophobin of Pleurotus ostreatus and an ABC transporter of Ralstonia metallidurans. These could represent molecular factors involved in the antagonistic mechanisms of Trichoderma and play a role in the three-way interaction with the plant and other microbes. 展开更多
关键词 differential proteins in vivo interactions induced disease resistance
在线阅读 下载PDF
Hydration film measurement on mica and coal surfaces using atomic force microscopy and interfacial interactions 被引量:4
9
作者 XING Yao-wen GUI Xia-hui CAO Yi-jun 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第6期1295-1305,共11页
The hydration film on particle surface plays an important role in bubble-particle adhesion in mineral flotation process. The thicknesses of the hydration films on natural hydrophobic coal and hydrophilic mica surfaces... The hydration film on particle surface plays an important role in bubble-particle adhesion in mineral flotation process. The thicknesses of the hydration films on natural hydrophobic coal and hydrophilic mica surfaces were measured directly by atomic force microscopy (AFM) based on the bending mode of the nominal constant compliance regime in AFM force curve in the present study. Surface and solid-liquid interfacial energies were calculated to explain the forming mechanism of the hydration film and atomic force microscopy data. The results show that there are significant differences in the structure and thickness of hydration films on coal and mica surfaces. Hydration film formed on mica surface with the thickness of 22.5 nm. In contrast, the bend was not detected in the nominal constant compliance regime. The van der Waals and polar interactions between both mica and coal and water molecules are characterized by an attractive effect, while the polar attractive free energy between water and mica (-87.36 mN/m) is significantly larger than that between water and coal (-32.89 mN/m), which leads to a thicker and firmer hydration layer on the mica surface. The interfacial interaction free energy of the coal/water/bubble is greater than that of mica. The polar attractive force is large enough to overcome the repulsive van der Waals force and the low energy barrier of film rupture, achieving coal particle bubble adhesion with a total interfacial free energy of-56.30 mN/m. 展开更多
关键词 hydration film atomic force microscope surface energy interfacial interaction
在线阅读 下载PDF
Interactions between gas flow and reversible chemical reaction in porous media 被引量:2
10
作者 JIANG Yuan-yong XU Zeng-he +1 位作者 ZHANG Meng-zhou BAI Li-yuan 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第5期1144-1154,共11页
Taking into consideration the gas compressibility and chemical reaction reversibility, a model was developed to study the interactions between gas flow and chemical reaction in porous media and resolved by the finite ... Taking into consideration the gas compressibility and chemical reaction reversibility, a model was developed to study the interactions between gas flow and chemical reaction in porous media and resolved by the finite volume method on the basis of the gas-solid reaction aA(g)+bB(s)cC(g)+dD(s).The numerical analysis shows that the equilibrium constant is an important factor influencing the process of gas-solid reaction. The stoichiometric coefficients, molar masses of reactant gas, product gas and inert gas are the main factors influencing the density of gas mixture. The equilibrium constant influences the gas flow in porous media obviously when the stoichiometric coefficients satisfy a/c≠1. 展开更多
关键词 POROUS MEDIA COMPRESSIBLE gas flow REVERSIBLE chemical reaction interaction
在线阅读 下载PDF
Cost-Effective Machining of Granite by Reducing Tribological Interactions 被引量:1
11
作者 LI Yuan 1, HUANG Hui 1, SHEN Jian-yun 1, XU Xi-peng 1, GAO Yong-sheng 2 (1. Province Key Lab of Stone Machining, Huaqiao University, Quanzhou 362011, China 2. Department of Mechanical Engineering, Hong Kong University of Science and T echnology, Hong Kong, China) 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第S1期123-,共1页
In order to implement cost-effective machining of gr anite materials with diamond impregnated tools, we should realize low tool w ear, low energy consumption, and high cutting efficiency, while the accuracy of the wor... In order to implement cost-effective machining of gr anite materials with diamond impregnated tools, we should realize low tool w ear, low energy consumption, and high cutting efficiency, while the accuracy of the workpiece surfaces are maintained to be satisfactory. It is understood that the main factors affecting the tool wear, the energy, and the efficiency during the machining process are related to the tribological interactions that occur at the interface between the diamond tool surface and the workpiece. Based on this consideration, we propose a new machining method to machine granite materia ls to achieve improved cost effectiveness. In the proposed method, the tribologi cal interactions are maintained to a minimum. Based on the analyses of the experimental results, the following conclusions can be drawn: The wear performance is greatly dependent on the machining parameters and their combination. Therefore, optimum machining parameters must be set up at first in order to optimize the tribological characteristics of segments and thereby sawbl ade performance. These may be realized by balancing the energy expended by frict ion and the mechanical load on diamond crystal. The geometry and structure of diamond segments are another important criterion f or the diamond saw blade. Using a seven-layer structure for multi-blades sawin g and applying segments with side slots for trimming application had greatly red uced the frictions in the sawing processes. The wetting and bonding between diamonds and matrix alloys have been considered as the prerequisite for high wear performance of the segments. Diamonds coated w ith Ti-Cr alloy by a unique technique can effectively improve its wetting c apability and provide more storage space for debris, thereby reducing friction i nteractions. 展开更多
关键词 GRANITE SAWING friction interaction cost-effe ctive
在线阅读 下载PDF
Extra contribution to the crystal stability of insensitive explosive TATB: The cooperativity of intermolecular interactions 被引量:1
12
作者 Zhi-xiang Zhang Yi-tao Si +5 位作者 Tao Yu Wei-peng Lai Yi-ding Ma Mao-chang Liu Ying-zhe Liu Bo-zhou Wang 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第7期88-98,共11页
An in-depth analysis on the cooperativity of intermolecular interactions including hydrogen bonding andπ-π stacking in 1,3,5-triamino-2,4,6-trinitrobenzene(TATB) crystal was studied. Two quantities, cooperativity ra... An in-depth analysis on the cooperativity of intermolecular interactions including hydrogen bonding andπ-π stacking in 1,3,5-triamino-2,4,6-trinitrobenzene(TATB) crystal was studied. Two quantities, cooperativity rate and energy, were defined to evaluate the nature and strength of cooperativity in a series of clusters diverging from 1D to 3D prototypes. The origin and mechanism of the cooperative effect were settled to demonstrate that the nature of cooperativity is determined by whether the non-covalent interactions compete or promote with each other, which is manifested by the changing trend of electron transfer. There exists obvious cooperative effect in intra-layer and inter-layer structures as they own the equivalent non-covalent interactions, while anti-cooperative effect is also observed if two interactions correlate with each other. On the whole, in the process of crystal formation, the apparent cooperativity is the check and balance of the two effects, which is capable to support a global interaction among all of molecules and contribute to the stabilization of system. Based on the results, one may get a new insight to understand the relationship between non-covalent interactions and low impact sensitivity. 展开更多
关键词 COOPERATIVITY Non-covalent interaction Low-sensitivity Explosives Charge transfer
在线阅读 下载PDF
Computational simulation of convective flow in the Earth crust under consideration of dynamic crust-mantle interactions 被引量:1
13
作者 赵崇斌 彭省临 +2 位作者 刘亮明 B.E.HOBBS A.ORD 《Journal of Central South University》 SCIE EI CAS 2011年第6期2080-2084,共5页
The finite element method was used to solve fluid dynamic interaction problems between the crust and mantle of the Earth. To consider different mechanical behaviours, the lithosphere consisting of the crust and upper ... The finite element method was used to solve fluid dynamic interaction problems between the crust and mantle of the Earth. To consider different mechanical behaviours, the lithosphere consisting of the crust and upper mantle was simulated as fluid-saturated porous rocks, while the upper aesthenospheric part of the mantle was simulated as viscous fluids. Since the whole lithosphere was computationally simulated, the dynamic interaction between the crust and the upper mantle was appropriately considered. In particular, the mixing of mantle fluids and crustal fluids was simulated in the corresponding computational model. The related computational simulation results from an example problem demonstrate that the mantle fluids can flow into the crust and mix with the crustal fluids due to the resulting convective flows in the crust-mantle system. Likewise, the crustal fluids can also flow into the upper mantle and mix with the mantle fluids. This kind of fluids mixing and exchange is very important to the better understanding of the governing processes that control the ore body formation and mineralization in the upper crust of the Earth. 展开更多
关键词 computational simulation crustal fluids mantle fluids fluid dynamic interaction
在线阅读 下载PDF
Nonlinear Interactions between the Quasi 5-day Wave and Tides Based on Meteor Radar Observations at Maui
14
作者 GU Jingxiao HUANG Chunming HUANG Kaiming 《空间科学学报》 CAS CSCD 北大核心 2015年第4期445-452,共8页
Nonlinear interactions between the quasi 5-day wave and tides based on meteor radar observation in the Mesosphere and Lower Thermosphere(MLT) at Maui are studied in this paper.Strong sum interaction between quasi 5-da... Nonlinear interactions between the quasi 5-day wave and tides based on meteor radar observation in the Mesosphere and Lower Thermosphere(MLT) at Maui are studied in this paper.Strong sum interaction between quasi 5-day wave and diurnal tide,and evident difference interaction between quasi 5-day wave and semidiurnal tide are observed during the time of attention.However,their difference and sum counterparts are clearly weaker.The secondary waves generated from those interactions beat with the tide and show intense modulation at the period of 5 days which confirms the existence of their interactions.Additionally,correlation coefficients among these waves are calculated to further explore their interactions and find that they can persist for several days although they are highly intermittent.The energy exchange among these waves can be reversible during the observational time.The periods when the significant difference interaction between the quasi 5-day wave and semidiurnal tide occur are much shorter than those when the significant sum interaction between the quasi 5-day wave and diurnal tide occur.Moreover,these two strong interactions can take place simultaneously.In generally,this study provides the proof of nonlinear interactions between quasi 5-day wave and tides which were seldom reported before. 展开更多
关键词 QUASI 5-day WAVE TIDES Nonlinear INTERACTION Mesos
在线阅读 下载PDF
Preparation and properties of a novel surfactant constructed by electrostatic interactions
15
作者 Junhui Wu Ting Pan +1 位作者 Xiaomei Pei Zhenggang Cui 《日用化学工业(中英文)》 CAS 北大核心 2023年第8期865-872,共8页
Taking stearic acid as the raw material,N-(2-(dimethylamino)ethyl)stearamide(C18N2N)was synthesized.A new surfactant was prepared by mixing C18N2N and cinnamic acid(TA)with fixed ratio.This surfactant was formed by no... Taking stearic acid as the raw material,N-(2-(dimethylamino)ethyl)stearamide(C18N2N)was synthesized.A new surfactant was prepared by mixing C18N2N and cinnamic acid(TA)with fixed ratio.This surfactant was formed by noncovalent electrostatic interactions,which avoided complicated synthetic procedures.The surface activity and rheological properties of the surfactant were investigated with a surface tensiometer and a rheometer.The critical micelle concentration(cmc)and the surface tension at cmc(γ_(cmc))of the surfactant were 0.11 mmol/L and 32.4 mN/m,indicative of strong aggregation and adsorption ability.The maximum amount adsorbed(Γ_(max))and the minimum molecular area occupied(A_(min))were 2.77μmol/m^(2)and 0.6 nm^(2).Wormlike micelles were formed at the concentration of 25 mmol/L.When the concentration was over 100 mmol/L,the zero-shear viscosity(η_(0))abruptly increased and then reached the maximum value for the surfactant of C18N2N/TA containing 150 mmol/L TA.The solution viscosity was as high as 1761.38 Pa·s.The effects of temperature on the rheological behavior were also considered.With the increase of temperature,the viscosity gradually increased.And when the temperature reached 40℃,η_(0)of the solution with the concentration of 100 mmol/L achieved the maximum value of 1370.386 Pa·s.When the temperature continued to rise,η_(0)began to decrease with further increasing temperature.A remarkable viscosity of 305.55 Pa·s was still remained at 50℃.The viscoelastic solutions showed good temperature resistance and shear resistance.The surfactant solutions applied as the fracturing fluid were also investigated.This surfactant also showed excellent sand-carrying performance,and the settling rate of the sand was merely 0.26 cm/min.This surfactant could be simply prepared and showed excellent performance,which expanded the preparation and application field of novel surfactants. 展开更多
关键词 electrostatic interaction stearic acid viscoelasticity fracturing fluid
在线阅读 下载PDF
Surface-covering water significantly amplifies the explosion impulse of shallow buried explosives 被引量:1
16
作者 Zhenyu Zhao Wenbo Gao +6 位作者 Jianwei Ren Zihan Lan Zhiyang Zhang Huiyao Gao Chao He Changye Ni Tianjian Lu 《Defence Technology(防务技术)》 2025年第6期156-172,共17页
While the moisture content of soil affects significantly the blast impulse of shallow buried explosives,the role of surface-covering water(SCW)on soil in such blast impulse remains elusive.A combined experimental and ... While the moisture content of soil affects significantly the blast impulse of shallow buried explosives,the role of surface-covering water(SCW)on soil in such blast impulse remains elusive.A combined experimental and numerical study has been carried out to characterize the effect of SCW on transferred impulse and loading magnitude of shallow buried explosives.Firstly,blast tests of shallow buried explosives were conducted,with and without the SCW,to quantitatively assess the blast loading impulse.Subsequently,finite element(FE)simulations were performed and validated against experimental measurement,with good agreement achieved.The validated FE model was then employed to predict the dynamic response of a fully-clamped metallic circular target,subjected to the explosive impact of shallow buried explosives with SCW,and explore the corresponding physical mechanisms.It was demonstrated that shallow buried explosives in saturated soil generate a greater impulse transferred towards the target relative to those in dry soil.The deformation displacement of the target plate is doubled.Increasing the height of SCW results in enhanced center peak deflection of the loaded target,accompanied by subsequent fall,due to the variation of deformation pattern of the loaded target from concentrated load to uniform load.Meanwhile,the presence of SCW increases the blast impulse transferred towards the target by three times.In addition,there exists a threshold value of the burial depth that maximizes the impact impulse.This threshold exhibits a strong sensitivity to SCW height,decreasing with increasing SCW height.An empirical formula for predicting threshold has been provided.Similar conclusions can be drawn for different explosive masses.The results provide technical guidance on blast loading intensity and its spatial distribution considering shallow buried explosives in coast-land battlefields,which can ultimately contribute to better protective designs. 展开更多
关键词 Shallow buried explosives Fluid-structure interaction Surface-covering water Impulse distribution
在线阅读 下载PDF
Comparative study on the oblique water-entry of high-speed projectile based on rigid-body and elastic-plastic body model 被引量:1
17
作者 Xiangyan Liu Xiaowei Cai +3 位作者 Zhengui Huang Yu Hou Jian Qin Zhihua Chen 《Defence Technology(防务技术)》 2025年第4期133-155,共23页
To examine the similarities and differences in the evolution of cavity,wetting and dynamics of a highspeed,oblique water-entry projectile with different positive angles of attack,a comparative analysis has been conduc... To examine the similarities and differences in the evolution of cavity,wetting and dynamics of a highspeed,oblique water-entry projectile with different positive angles of attack,a comparative analysis has been conducted based on the numerical results of two mathematical models,the rigid-body model and fluid-structure interaction model.In addition,the applicable scope of the above two methods,and the structural response characteristics of the projectile have also been investigated.Our results demonstrate that:(1) The impact loads and angular motion of the projectile of the rigid-body method are more likely to exhibit periodic variations due to the periodic tail slap,its range of positive angles of attack is about α<2°.(2) When the projectile undergone significant wetting,a strong coupling effect is observed among wetting,structural deformation,and projectile motion.With the applied projectile shape,it is observed that,when the projectile bends,the final wetting position is that of Part B(cylinder of body).With the occu rrence of this phenomenon,the projectile ballistics beco me completely unstable.(3) The force exerted on the lower surface of the projectile induced by wetting is the primary reason of the destabilization of the projectile traj ectory and structu ral deformation failure.Bending deformation is most likely to appear at the junction of Part C(cone of body) and Part D(tail).The safe angles of attack of the projectile stability are found to be about α≤2°. 展开更多
关键词 Fluid-structure interaction Rigid-body model Elastic-plastic model Structural deformation Impact loads Structural safety of projectile
在线阅读 下载PDF
Flow field distribution and overpressure characteristics inside the crew compartment of a truck-mounted howitzer under the effect of muzzle blast 被引量:1
18
作者 Shengcheng Wei Linfang Qian +2 位作者 Yadong Xu Qiang Yin Xinyu Xiong 《Defence Technology(防务技术)》 2025年第2期190-205,共16页
The muzzle blast overpressure induces disturbances in the flow field inside the crew compartment(FFICC)of a truck-mounted howitzer during the artillery firing.This overpressure is the primary factor preventing personn... The muzzle blast overpressure induces disturbances in the flow field inside the crew compartment(FFICC)of a truck-mounted howitzer during the artillery firing.This overpressure is the primary factor preventing personnel from firing artillery within the cab.To investigate the overpressure characteristics of the FFICC,a foreign trade equipment model was used as the research object,and a numerical model was established to analyze the propagation of muzzle blast from the muzzle to the interior of the crew compartment under extreme firing condition.For comparative verification,the muzzle blast experiment included overpressure data from both the flow field outside the crew compartment(FFOCC)and the FFICC,as well as the acceleration data of the crew compartment structure(Str-CC).The research findings demonstrate that the overpressure-time curves of the FFICC exhibit multi-peak characteristics,while the pressure wave shows no significant discontinuity.The enclosed nature of the cab hinders the dissipation of pressure wave energy within the FFICC,leading to sustained high-amplitude overpressure.The frameskin structure helps attenuate the impact of muzzle blast on the FFICC.Conversely,local high overpressure caused by the convex or concave features of the cab's exterior significantly amplifies the overpressure amplitude within the FFICC. 展开更多
关键词 Truck-mounted howitzer Muzzle blast Flow field inside the crew compartment(FFICC) Overpressure characteristics Flow-structure interaction
在线阅读 下载PDF
Identification of shared key genes and pathways in osteoarthritis and sarcopenia patients based on bioinformatics analysis
19
作者 SUN Yuyan LUO Ziyu +6 位作者 LING Huixian WU Sha SHEN Hongwei FU Yuanyuan NGO Thainamanh WANG Wen KONG Ying 《中南大学学报(医学版)》 北大核心 2025年第3期430-446,共17页
Objective:Osteoarthritis(OA)and sarcopenia are significant health concerns in the elderly,substantially impacting their daily activities and quality of life.However,the relationship between them remains poorly underst... Objective:Osteoarthritis(OA)and sarcopenia are significant health concerns in the elderly,substantially impacting their daily activities and quality of life.However,the relationship between them remains poorly understood.This study aims to uncover common biomarkers and pathways associated with both OA and sarcopenia.Methods:Gene expression profiles related to OA and sarcopenia were retrieved from the Gene Expression Omnibus(GEO)database.Differentially expressed genes(DEGs)between disease and control groups were identified using R software.Common DEGs were extracted via Venn diagram analysis.Gene ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)enrichment analyses were conducted to identify biological processes and pathways associated with shared DEGs.Protein-protein interaction(PPI)networks were constructed,and candidate hub genes were ranked using the maximal clique centrality(MCC)algorithm.Further validation of hub gene expression was performed using 2 independent datasets.Receiver operating characteristic(ROC)curve analysis was used to evaluate the predictive value of key genes for OA and sarcopenia.Mouse models of OA and sarcopenia were established.Hematoxylin-eosin and Safranin O/Fast Green staining were used to validate the OA model.The sarcopenia model was validated via rotarod testing and quadriceps muscle mass measurement.Real-time reverse transcription PCR(real-time RT-PCR)was employed to assess the mRNA expression levels of candidate key genes in both models.Gene set enrichment analysis(GSEA)was conducted to identify pathways associated with the selected shared key genes in both diseases.Results:A total of 89 common DEGs were identified in the gene expression profiles of OA and sarcopenia,including 76 upregulated and 13 downregulated genes.These 89 DEGs were significantly enriched in protein digestion and absorption,the PI3K-Akt signaling pathway,and extracellular matrix-receptor interaction.PPI network analysis and MCC algorithm analysis of the 89 common DEGs identified the top 17 candidate hub genes.Based on the differential expression analysis of these 17 candidate hub genes in the validation datasets,AEBP1 and COL8A2 were ultimately selected as the common key genes for both diseases,both of which showed a significant upregulation trend in the disease groups(all P<0.05).The value of area under the curve(AUC)for AEBP1 and COL8A2 in the OA and sarcopenia datasets were all greater than 0.7,indicating that both genes have potential value in predicting OA and sarcopenia.Real-time RT-PCR results showed that the mRNA expression levels of AEBP1 and COL8A2 were significantly upregulated in the disease groups(all P<0.05),consistent with the results observed in the bioinformatics analysis.GSEA revealed that AEBP1 and COL8A2 were closely related to extracellular matrix-receptor interaction,ribosome,and oxidative phosphorylation in OA and sarcopenia.Conclusion:AEBP1 and COL8A2 have the potential to serve as common biomarkers for OA and sarcopenia.The extracellular matrix-receptor interaction pathway may represent a potential target for the prevention and treatment of both OA and sarcopenia. 展开更多
关键词 OSTEOARTHRITIS SARCOPENIA BIOINFORMATICS extracellular matrix-receptor interaction key genes
在线阅读 下载PDF
Estimation of peer pressure in dynamic homogeneous social networks
20
作者 Jie Liu Pengyi Wang +1 位作者 Jiayang Zhao Yu Dong 《中国科学技术大学学报》 北大核心 2025年第5期36-49,35,I0001,I0002,共17页
Social interaction with peer pressure is widely studied in social network analysis.Game theory can be utilized to model dynamic social interaction,and one class of game network models assumes that people’s decision p... Social interaction with peer pressure is widely studied in social network analysis.Game theory can be utilized to model dynamic social interaction,and one class of game network models assumes that people’s decision payoff functions hinge on individual covariates and the choices of their friends.However,peer pressure would be misidentified and induce a non-negligible bias when incomplete covariates are involved in the game model.For this reason,we develop a generalized constant peer effects model based on homogeneity structure in dynamic social networks.The new model can effectively avoid bias through homogeneity pursuit and can be applied to a wider range of scenarios.To estimate peer pressure in the model,we first present two algorithms based on the initialize expand merge method and the polynomial-time twostage method to estimate homogeneity parameters.Then we apply the nested pseudo-likelihood method and obtain consistent estimators of peer pressure.Simulation evaluations show that our proposed methodology can achieve desirable and effective results in terms of the community misclassification rate and parameter estimation error.We also illustrate the advantages of our model in the empirical analysis when compared with a benchmark model. 展开更多
关键词 dynamic network game theory HOMOGENEITY peer pressure social interaction
在线阅读 下载PDF
上一页 1 2 11 下一页 到第
使用帮助 返回顶部