期刊文献+
共找到2,919篇文章
< 1 2 146 >
每页显示 20 50 100
Heterogeneities of grain boundary contact for simulation of laboratoryscale mechanical behavior of granitic rocks
1
作者 Xiongyu Hu Marte Gutierrez Zhiwei Yan 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第7期2629-2644,共16页
From a practical point of view,grain structure heterogeneities are key parameters that control the rock response and still remains a challenge to incorporate in a quantitative manner.One of the less discussed topics i... From a practical point of view,grain structure heterogeneities are key parameters that control the rock response and still remains a challenge to incorporate in a quantitative manner.One of the less discussed topics in the context of the grain-based model(GBM)in the particle flow code(PFC)is the contact heterogeneities and the appropriate contact model to mimic the grain boundary behavior.Generally,the smooth joint(SJ)model and linear parallel bond(LPB)model are used to simulate the grain boundary behavior.However,the literature does not document the suitability of different models for specific problems.Another challenge in implementing GBM in PFC is that only a single bonding parameter is used at the grain boundaries.The aim of this study is to investigate the responses of a laboratory-scale specimen with SJ and LPB models,considering grain boundary heterogeneous and homogeneous contact parameters.Uniaxial and biaxial compression tests are performed to calibrate the response of Creighton granite.The stressestrain curves,volumetric dilation,inter-crack(crack in the grain boundary),and intra-crack(crack within the grain)development,and failure patterns associated with different contact models are examined.It was found that both the SJ and LPB models can reproduce the pre-peak behavior observed for a granitic rock type.However,the LPB model is unable to reproduce the post-peak behavior.Due to the large interlocking effect originating from the balls in contact and the ball size in the LPB model,local dilation is induced at the grain boundaries.This overestimates the volumetric dilation and residual shear strength.The LPB model tends to result in discontinuous inter-cracks and stress localization in the rock specimen,resulting in fine fragments at the rock surface during failure. 展开更多
关键词 Grain boundary contact Smooth joint(SJ)model Linear parallel bond(LPB)model Contact heterogeneities Particle flow code(PFC) Granitic rock
下载PDF
Study on the Effects of Land Surface Heterogeneities in Temperature and Moisture on Annual Scale Regional Climate Simulation 被引量:4
2
作者 曾新民 刘金波 +3 位作者 马柱国 宋帅 席朝笠 王汉杰 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2010年第1期151-163,共13页
The "combined approach", which is suitable to represent subgrid land surface heterogeneity in both interpatch and intra-patch variabilities, is employed in the BiOsphere/Atmosphere Transfer Scheme (BATS) as a land... The "combined approach", which is suitable to represent subgrid land surface heterogeneity in both interpatch and intra-patch variabilities, is employed in the BiOsphere/Atmosphere Transfer Scheme (BATS) as a land surface component of the regional climate model RegCM3 to consider the heterogeneities in temperature and moisture at the land surface, and then annual-scale simulations for 5 years (1988-1992) were conducted. Results showed that on the annual scale, the model's response to the heterogeneities is quite sensitive, and that the effect of the temperature heterogeneity (TH) is more pronounced than the moisture heterogeneity (MH). On the intraannual scale, TH may lead to more (less) precipitation in warm (cold) seasons, and hence lead to larger intraannual variability in precipitation; the major MH effects may be lagged by about 1 month during the warm, rainy seasons, inducing -6% more precipitation for some sub-regions. Additionally, the modeled climate for the northern sub-regions shows larger sensitivities to the land surface heterogeneities than those for the southern sub-regions. Since state-of-art land surface models seldom account for surface intra-patch variabilities, this study emphasizes the importance of including this kind of variability in the land surface models. 展开更多
关键词 regional climate model heterogeneities in temperature and moisture simulation on the annual scale sensitivity
下载PDF
3D geo-cellular static virtual outcrop model and its implications for reservoir petro-physical characteristics and heterogeneities
3
作者 Muhammad Usman Numair A.Siddiqui +5 位作者 Shi-Qi Zhang Manoj J.Mathew Ya-Xuan Zhang Muhammad Jamil Xue-Liang Liu Nisar Ahmed 《Petroleum Science》 SCIE CAS CSCD 2021年第5期1357-1369,共13页
Geostatistical data plays a vibrant role for surface-based reservoir modeling through outcrop analogues,which is used to understand three-dimensional(3D)variability of petrophysical properties.The main purpose of this... Geostatistical data plays a vibrant role for surface-based reservoir modeling through outcrop analogues,which is used to understand three-dimensional(3D)variability of petrophysical properties.The main purpose of this study is to improvise the surface-based 3D geo-modeling to demonstrate petrophysical characteristics and heterogeneities of Sandakan reservoirs,NW Borneo.We used point cloud data from Light Detection and Ranging(Li DAR)to build high-resolution virtual outcrop modeling(VOM)onto which we mapped 6 different lithofacies.Porosity and permeability of core plugs were measured to determine the average variance of petrophysical properties for each lithofacies.By utilizing the integration of VOMs analogues and petrophysical properties in Petrel^(TM),we demonstrated the distribution and associations of all lithofacies in pseudo wells that have inherent thin beds heterogeneities in 3D geocellular model.The results concluded that the heterogeneity of thin beds in lithofacies is dependent on porosity and permeability with input dataset.According to the final model,cross-bedding sandstone(CBS),hummocky cross-stratified sandstone(HCSS)and trough cross-bedding sandstone(TCBS)show good reservoir quality due to high porosity ranging from:25.6%to 20.4%and,19.3%-14.5%,and permeability ranging from:74.03 mD to 66.84 mD and,64.86 mD to 21.01 mD.In contrast,massive to weak laminae sandstone(MWLS)and bioturbated sandstone(BS)show fair to poor reservoir quality,caused baffling of surrounding mud sediments in the reservoir lithofacies.Results also revealed that Li DAR based VOM with petrophysical properties can significantly reduce the risk and minimize the cost of reservoir modeling in petroleum industry. 展开更多
关键词 Virtual outcrop modeling Lithofacies 3D geo-cellular model Petrophysical properties Reservoir heterogeneities
下载PDF
Effect of Heterogeneities in Soil on Spatial Variation of Peak Ground Acceleration
4
作者 Mohammad Ahmed Hussain Ramancharla Pradeep Kumar 《Journal of Civil Engineering and Architecture》 2010年第11期45-52,共8页
In the proximity of an active fault, spatial variation of peak ground motion is significantly affected by the faulting mechanism. It has been observed that near fault ground motions consists of different characteristi... In the proximity of an active fault, spatial variation of peak ground motion is significantly affected by the faulting mechanism. It has been observed that near fault ground motions consists of different characteristics compared to the far fault ground motions. Near fault records, in the distance range of less than 100 m from the faults are not available except for few cases. Therefore numerical simulation of ground motions for such near-fault situations is necessary. In addition to the understanding of the phenomenon of near fault ground motion there is a need to enhance our understanding of the possible potential hazard that can be caused due to the future rupture activity by understanding the phenomenon of surface faulting. In this paper we propose numerical simulation based on discrete modeling to investigate the fault rupture propagation and its effect on the surface peak ground acceleration. In the present two dimensional study rupture propagation due to bedrock motion has been observed for different shear wave velocity. A model of size 1000× 150 m is selected for this purpose. It has been observed that as the stiffness of the media is decreasing, the affected surface is decreasing and also width of the shear crack zone is decreasing. Secondly, we attempted to study the ground motion on the surface due to the bedrock motion in presence of boulders in the soil media by keeping the boulder at different positions. We find that there is an increase in the shear zone as well as the PGA on the surface when the boulder is present on the foot wall and in the vicinity of the rupture zone. Finally, we performed the analysis using layered media and studied the affect of crack propagation and also the variation of peak accelerations. Findings from the study can be utilized to assess the damage potential of the near fault areas. 展开更多
关键词 PGA heterogeneities AMPLIFICATION fault motion.
下载PDF
Dosimetric Evaluation of Heterogeneities in Small Circular Fields of 6 MV Photon Beams with EBT2 and EDR2 Films: Comparison with Monte Carlo Calculation
5
作者 Ali Mohammad Hassan A. Nedaie +3 位作者 Mehran YarAhmadi Nooshin Banaee Mansour Naderi Zohre Tizmaghz 《Journal of Modern Physics》 2014年第16期1608-1616,共9页
The influence of dose variation due to heterogeneities in narrow photon beams used in stereotactic radiosurgery has been investigated. Since the lateral electronic disequilibrium and existence of steep dose gradients ... The influence of dose variation due to heterogeneities in narrow photon beams used in stereotactic radiosurgery has been investigated. Since the lateral electronic disequilibrium and existence of steep dose gradients in small fields and the presence of heterogeneities can intensify these problems, in this study the effects of heterogeneities on 6 MV small photon beams produced by circular cone collimators with 5, 10, 15, 20 and 30 mm diameters are investigated. The heterogeneities include 3 cm Cork with density of 0.2 g/cm3 instead of lung and 3 cm Polytetrafluoroethylene (P.T.F.E) with density of 2.2 g/cm3 as bone. The measurements were carried out with EBT2 gafchromic and EDR2 radiographic films. Simulation was done by MCNP Monte Carlo Code (MCNP5). The depth dose curves in heterogeneous phantom were compared with homogeneous phantom. A good agreement was obtained within film and Monte Carlo calculations in presence of low density heterogeneity and also in the presence of high density heterogeneity. Monte Carlo results showed good agreement after stopping power correction. 展开更多
关键词 STEREOTACTIC RADIOSURGERY heterogeneities Film DOSIMETRY MONTE Carlo Calculation
下载PDF
Deformation behavior of materials in micro-forming with consideration of intragranular heterogeneities 被引量:2
6
作者 Zhen-wu MA Guo-quan TONG Feng CHEN 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第3期616-626,共11页
To describe the relationship between the whole material deformation behavior and each grain deformation behavior inmicro-forming,experimental and numerical modelling methods were employed.Tensile test results reveal t... To describe the relationship between the whole material deformation behavior and each grain deformation behavior inmicro-forming,experimental and numerical modelling methods were employed.Tensile test results reveal that contrary to the valueof flow stress,the scatter of flow stress decreases with the increase of thickness-to-grain diameter(T/d)ratio.Microhardnessevaluation results show that each grain owns unique deformation behavior and randomly distributes in each specimen.The specimenwith less number of grains would be more likely to form an easy deformation zone and produce the concentration of plasticdeformation.Based on the experiment results,a size-dependent model considering the effects of grain size,geometry size,and thedeformation behavior of each grain was developed.And the effectiveness and practicability of the size-dependent model wereverified by experimental results. 展开更多
关键词 MICRO-FORMING deformation behavior size effect model intragranular heterogeneity
下载PDF
Remaining oil distribution in models with different heterogeneities after CO_(2) WAG injection:Visual research by nuclear magnetic resonance technique 被引量:3
7
作者 WANG Ye-fei LI Zong-yang +2 位作者 ZHANG Shi-ming LIU De-xin DING Ming-chen 《Journal of Central South University》 SCIE EI CAS CSCD 2021年第5期1412-1421,共10页
Water alternating gas(WAG)injection is a widely used strategy for enhancing oil recovery(EOR)during gas flooding,and the mechanisms,operating parameters,and influencing factors of which have been extensively studied.H... Water alternating gas(WAG)injection is a widely used strategy for enhancing oil recovery(EOR)during gas flooding,and the mechanisms,operating parameters,and influencing factors of which have been extensively studied.However,with respect to its capacity in expanding macroscopic sweep volume under varying heterogeneities,the related results appear inadequate.In this research,three cores with different heterogeneities were used and flooded by the joint water and CO_(2) WAG,then the effects of heterogeneity on oil recovery were determined.More importantly,the cores after CO_(2) WAG injection were investigated using the nuclear magnetic resonance(NMR)technique for remaining oil distribution research,which could help us to understand the capacity of CO_(2) WAG in enlarging sweep volume at different heterogeneities.The results show that the presence of heterogeneity may largely weaken the effectiveness of water flooding,the more severe the heterogeneity,the worse the water flooding.The WAG injection of CO_(2) performs well in EOR after water flooding for all the cores with different heterogeneities;however,it could barely form a complete or full sweep throughout the low-permeability region,and un-swept bypassed regions remain.The homogeneous core is better developed by the injection of the joint water and CO_(2) WAG than the heterogeneous and fractured cases. 展开更多
关键词 heterogeneous reservoir enhancing oil recovery CO_(2)WAG injection sweep volume remaining oil nuclear magnetic resonance
下载PDF
A Mesoscale Analysis of Heavy Rain Caused by Frontal and Topographical Heterogeneities on Taiwan Island
8
作者 景丽 陆汉城 +2 位作者 王汉杰 朱民 寇正 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2004年第6期909-922,共14页
The prevailing mesoscale model MM5 (V3) is used to simulate a heavy rain case caused by interac- tion between a move-in front and topographical heterogeneities on Taiwan Island. It is found that both thermodynamic a... The prevailing mesoscale model MM5 (V3) is used to simulate a heavy rain case caused by interac- tion between a move-in front and topographical heterogeneities on Taiwan Island. It is found that both thermodynamic and dynamic ?elds along the front are heterogeneous in time and space. The heterogene- ity becomes more signi?cant as the e?ect of topography is added on. The heterogeneous distribution of physical variables along the front is the main reason for the heterogeneous frontal rain band; the optimum cooperation of the low level and upper level jet is another reason for the development of the rain band. Topography can strengthen the rainfall and causes extremely heavy rain cells. Updraft induced by topog- raphy extends to a rather low level, while the uplifted air by frontal circulation can reach to higher levels. The quasi-steady topographic circulation overlaps the frontal circulation when the front moves over Taiwan Island; the advantageous cooperation of various mesoscale conditions causes the large upward velocity on the windward side of the island. 展开更多
关键词 frontal heterogeneity heavy storm topographical circulation MM5 Taiwan Island
下载PDF
Scale lengths of heterogeneities under Tibet
9
作者 Yingcai Zheng 《Earthquake Science》 CSCD 2012年第5期409-414,共6页
Important information about small-scale heterogeneities is hardly accessible by the traditional deterministic seismic tomography. Fluctuations of the phase and the logarithmic amplitude of direct teleseismic plane P w... Important information about small-scale heterogeneities is hardly accessible by the traditional deterministic seismic tomography. Fluctuations of the phase and the logarithmic amplitude of direct teleseismic plane P waves can be used to characterize small-scale heterogeneities. Seismic data recorded by the Hi-CLIMB array are used to analyze the average power spectrum of the small-scale velocity heterogeneities under Tibet. Coherence functions of the logarithmic amplitude and the phase fluctuations due to different earthquakes from different back azimuths show consistent characteristics, indicating that fluctuations are due to heterogeneities under the stations. Assuming that the heterogeneities are statistically stationary and distributed within a layer, we invert for the average heterogeneity spectrum by fitting both the logarithmic amplitude and the phase coherence data. Multiscale nature of the heterogeneity is evident. The inverted power spectrum is "red" at the large-scale end, meaning that the power spectrum decreases as the length scale decreases. Such a decreasing trend stops at smaller scales -20-50 km and 10 km. This may indicate that mantle convection is not effective in destroying smaller heterogeneities. 展开更多
关键词 seismic tomography mantle heterogeneity SCATTERING coherence function
下载PDF
Evolution and Simulation of Spatial-temporal Heterogeneities in Ecological Background Quality of Changsha City
10
作者 YU Bingjie TANG Youhai +2 位作者 WEI Zhe BI Linglan ZHANG Lei 《Journal of Landscape Research》 2016年第6期46-52,共7页
By GIS and ENVI,TM/ETM remote sensing images of five districts(Yuelu District,Furong District,Yuhua District,Tianxin District and Kaifu District) in Changsha City center in 2005,2010 and 2015 were interpreted.Moreover... By GIS and ENVI,TM/ETM remote sensing images of five districts(Yuelu District,Furong District,Yuhua District,Tianxin District and Kaifu District) in Changsha City center in 2005,2010 and 2015 were interpreted.Moreover,distribution chart for ecological background factors in 2020 was simulated by using CA-Markov module in IDRISI.Using principal component analysis,evaluation model for ecological background quality of the city was established.Via circle analysi s,GS+semi variance function analysis,hot spot area analysis and grey correlation analysis,integrated analysis and evaluation on spatial heterogeneity evolution of ecological background quality in research region were conducted.Results showed that firstly Changsha overall has formed ecological pattern of landscape island city,but ecological background started to show the evolution trend of high heterogeneity and fragmentation under the construction land expansion,and ecological background quality of the city declined from 0.300,6 to 0.257,1 during 2005-2020.Secondly,ecological background quality of Changsha City had typical circle and axial gradient structure,and "eco tone" had the most violent evolution.Thirdly,spatial structure of ecological background quality had region,time and direction heterogeneities,and spatial heterogeneity of region was the most important.Fourthly,hot spot area distribution of ecological background quality evolution showed the "frog jump" trend of gathering in marginal zone and diffusing to peripheral zone.Fifthly,in driving factors of ecological background quality,industrialization rate had the highest grey correlation degree(0.842,1),and grey absolute correlation degree between ecological background quality in Yuelu District and industrialization rate was the highest(0.603,1). 展开更多
关键词 Changsha City Ecological background quality Spatial heterogeneity Simulation prediction Grey correlation
下载PDF
Association and its population heterogeneities between low-density lipoprotein cholesterol and all-cause and cardiovascular mortality:A population-based cohort study
11
作者 Jiapeng Lu Haibo Zhang +9 位作者 Bowang Chen Yang Yang Jianlan Cui Wei Xu Lijuan Song Hao Yang Wenyan He Yan Zhang Wenyao Peng Xi Li 《Chinese Medical Journal》 SCIE CAS CSCD 2024年第17期2075-2083,共9页
Background:The association and its population heterogeneities between low-density lipoprotein cholesterol(LDL-C)and all-cause and cardiovascular mortality remain unknown.We aimed to examine the dose-dependent associat... Background:The association and its population heterogeneities between low-density lipoprotein cholesterol(LDL-C)and all-cause and cardiovascular mortality remain unknown.We aimed to examine the dose-dependent associations of LDL-C levels with specific types of cardiovascular disease(CVD)mortality and heterogeneities in the associations among different population subgroups.Methods:A total of 2,968,462 participants aged 35-75 years from China Health Evaluation And risk Reduction through nationwide Teamwork(ChinaHEART)(2014-2019)were included.Cox proportional hazard models and Fine-Gray subdistribution hazard models were used to estimate associations between LDL-C categories(<70.0,70.0-99.9,100.0-129.9[reference group],130.0-159.9,160.0-189.9,and≥190.0 mg/dL)and all-cause and cause-specific mortality.Results:During a median follow-up of 3.7 years,57,391 and 23,241 deaths from all-cause and overall CVD were documented.We observed J-shaped associations between LDL-C and death from all-cause,overall CVD,coronary heart disease(CHD),and ischemic stroke,and an L-shaped association between LDL-C and hemorrhagic stroke(HS)mortality(P for non-linearity<0.001).Compared with the reference group(100.0-129.9 mg/dL),very low LDL-C levels(<70.0 mg/dL)were significantly associated with increased risk of overall CVD(hazard ratio[HR]:1.10,95%confidence interval[CI]:1.06-1.14)and HS mortality(HR:1.37,95%CI:1.29-1.45).Very high LDL-C levels(≥190.0 mg/dL)were associated with increased risk of overall CVD(HR:1.51,95%CI:1.40-1.62)and CHD mortality(HR:2.08,95%CI:1.92-2.24).The stronger associations of very low LDL-C with risk of CVD mortality were observed in individuals with older age,low or normal body mass index,low or moderate 10-year atherosclerotic CVD risk,and those without diagnosed CVD or taking statins.Stronger associations between very high LDL-C levels and all-cause and CVD mortality were observed in younger people.Conclusions:People with very low LDL-C had a higher risk of all-cause,CVD,and HS mortality;those with very high LDL-C had a higher risk of all-cause,CVD,and CHD mortality.On the basis of our findings,comprehensive health assessment is needed to evaluate cardiovascular risk and implement appropriate lipid-lowering therapy for people with very low LDL-C. 展开更多
关键词 Low-density lipoprotein cholesterol MORTALITY Association study Population heterogeneity Prospective cohort study
原文传递
Enabling heterogeneous catalysis to achieve carbon neutrality: Directional catalytic conversion of CO_(2) into carboxylic acids 被引量:7
12
作者 Xiaofei Zhang Wenhuan Huang +4 位作者 Le Yu Max García-Melchor Dingsheng Wang Linjie Zhi Huabin Zhang 《Carbon Energy》 SCIE EI CAS CSCD 2024年第3期1-35,共35页
The increase in anthropogenic carbon dioxide(CO_(2))emissions has exacerbated the deterioration of the global environment,which should be controlled to achieve carbon neutrality.Central to the core goal of achieving c... The increase in anthropogenic carbon dioxide(CO_(2))emissions has exacerbated the deterioration of the global environment,which should be controlled to achieve carbon neutrality.Central to the core goal of achieving carbon neutrality is the utilization of CO_(2) under economic and sustainable conditions.Recently,the strong need for carbon neutrality has led to a proliferation of studies on the direct conversion of CO_(2) into carboxylic acids,which can effectively alleviate CO_(2) emissions and create high-value chemicals.The purpose of this review is to present the application prospects of carboxylic acids and the basic principles of CO_(2) conversion into carboxylic acids through photo-,electric-,and thermal catalysis.Special attention is focused on the regulation strategy of the activity of abundant catalysts at the molecular level,inspiring the preparation of high-performance catalysts.In addition,theoretical calculations,advanced technologies,and numerous typical examples are introduced to elaborate on the corresponding process and influencing factors of catalytic activity.Finally,challenges and prospects are provided for the future development of this field.It is hoped that this review will contribute to a deeper understanding of the conversion of CO_(2) into carboxylic acids and inspire more innovative breakthroughs. 展开更多
关键词 carbon neutrality carboxylic acids CO_(2)conversion heterogeneous catalyst in situ technology
下载PDF
Insight into the spoilage heterogeneity of meat-borne bacteria isolates with high-producing collagenase 被引量:2
13
作者 Haodong Wang Liangting Shao +3 位作者 Jinhao Zhang Xinglian Xu Jianjun Li Huhu Wang 《Food Science and Human Wellness》 SCIE CSCD 2024年第3期1402-1409,共8页
Chilled chicken is inevitably contaminated by microorganisms during slaughtering and processing,resulting in spoilage.Cutting parts of chilled chicken,especially wings,feet,and other skin-on products,are abundant in c... Chilled chicken is inevitably contaminated by microorganisms during slaughtering and processing,resulting in spoilage.Cutting parts of chilled chicken,especially wings,feet,and other skin-on products,are abundant in collagen,which may be the primary target for degradation by spoilage microorganisms.In this work,a total of 17 isolates of spoilage bacteria that could secrete both collagenase and lipase were determined by raw-chicken juice agar(RJA)method,and the results showed that 7 strains of Serratia,Aeromonas,and Pseudomonas could significantly decompose the collagen ingredients.The gelatin zymography showed that Serratia liquefaciens(F5)and(G7)had apparent degradation bands around 50 kDa,and Aeromonas veronii(G8)and Aeromonas salmonicida(H8)had a band around.65 and 95 kDa,respectively.The lipase and collagenase activities were detected isolate-by-isolate,with F5 showing the highest collagenase activity.For spoilage ability on meat in situ,F5 performed strongest in spoilage ability,indicated by the total viable counts,total volatile basic nitrogen content,sensory scores,lipase,and collagenase activity.This study provides a theoretical basis for spoilage heterogeneity of strains with high-producing collagenase in meat. 展开更多
关键词 BACTERIA Chilled chicken HETEROGENEITY COLLAGENASE SPOILAGE
下载PDF
Neurophysiological, histological, and behavioral characterization of animal models of distraction spinal cord injury: a systematic review 被引量:1
14
作者 Bo Han Weishi Liang +4 位作者 Yong Hai Duan Sun Hongtao Ding Yihan Yang Peng Yin 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第3期563-570,共8页
Distraction spinal cord injury is caused by some degree of distraction or longitudinal tension on the spinal cord and commonly occurs in patients who undergo corrective operation for severe spinal deformity.With the i... Distraction spinal cord injury is caused by some degree of distraction or longitudinal tension on the spinal cord and commonly occurs in patients who undergo corrective operation for severe spinal deformity.With the increased degree and duration of distraction,spinal cord injuries become more serious in terms of their neurophysiology,histology,and behavior.Very few studies have been published on the specific characteristics of distraction spinal cord injury.In this study,we systematically review 22 related studies involving animal models of distraction spinal cord injury,focusing particularly on the neurophysiological,histological,and behavioral characteristics of this disease.In addition,we summarize the mechanisms underlying primary and secondary injuries caused by distraction spinal cord injury and clarify the effects of different degrees and durations of distraction on the primary injuries associated with spinal cord injury.We provide new concepts for the establishment of a model of distraction spinal cord injury and related basic research,and provide reference guidelines for the clinical diagnosis and treatment of this disease. 展开更多
关键词 animal models behavior DISTRACTION heterogeneity HISTOLOGY mechanism NEUROPHYSIOLOGY spinal cord injury systematic review tension
下载PDF
Synergy of heterogeneous Co/Ni dual atoms enabling selective C-O bond scission of lignin coupling with in-situ N-functionalization 被引量:1
15
作者 Baoyu Wang Jinshu Huang +3 位作者 Hongguo Wu Ximing Yan Yuhe Liao Hu Li 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第5期16-25,共10页
Selective cleavage of Csp^(2)-OCH_(3)bond in lignin without breaking other types of C-O bonds followed by N-functionalization is fascinating for on-purpose valorization of biomass.Here,a Co/Ni-based dual-atom catalyst... Selective cleavage of Csp^(2)-OCH_(3)bond in lignin without breaking other types of C-O bonds followed by N-functionalization is fascinating for on-purpose valorization of biomass.Here,a Co/Ni-based dual-atom catalyst CoNiDA@NC prepared by in-situ evaporation and acid-etching of metal species from tailor-made metal–organic frameworks was efficient for reductive upgrading of various lignin-derived phenols to cyclohexanols(88.5%–99.9%yields),which had ca.4 times higher reaction rate than the single-atom catalyst and was superior to state-of-the-art heterogeneous catalysts.The synergistic catalysis of Co/Ni dual atoms facilitated both hydrogen dissociation and hydrogenolysis steps,and could optimize adsorption configuration of lignin-derived methoxylated phenols to further favor the Csp^(2)-OCH_(3)cleavage,as elaborated by theoretical calculations.Notably,the CoNi_(DA)@NC catalyst was highly recyclable,and exhibited excellent demethoxylation performance(77.1%yield)in real lignin monomer mixtures.Via in-situ cascade conversion processes assisted by dual-atom catalysis,various high-value N-containing chemicals,including caprolactams and cyclohexylamines,could be produced from lignin. 展开更多
关键词 Biomass conversion Heterogeneous catalysis LIGNIN Dual-atom catalyst Selective C-ocleavage
下载PDF
Efficient Electromagnetic Wave Absorption and Thermal Infrared Stealth in PVTMS@MWCNT Nano‑Aerogel via Abundant Nano‑Sized Cavities and Attenuation Interfaces 被引量:1
16
作者 Haoyu Ma Maryam Fashandi +5 位作者 Zeineb Ben Rejeb Xin Ming Yingjun Liu Pengjian Gong Guangxian Li Chul B.Park 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第1期370-383,共14页
Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT... Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT aerogel structure shows nano-pore size(30-40 nm),high specific surface area(559 m^(2)g^(−1)),high void fraction(91.7%)and enhanced mechanical property:(1)the nano-pore size is beneficial for efficiently blocking thermal conduction and thermal convection via Knudsen effect(beneficial for infrared(IR)stealth);(2)the heterogeneous interface was beneficial for IR reflection(beneficial for IR stealth)and MWCNT polarization loss(beneficial for electromagnetic wave(EMW)attenuation);(3)the high void fraction was beneficial for enhancing thermal insulation(beneficial for IR stealth)and EMW impedance match(beneficial for EMW attenuation).Guided by the above theoretical design strategy,PVTMS@MWCNT nano-aerogel shows superior EMW absorption property(cover all Ku-band)and thermal IR stealth property(ΔT reached 60.7℃).Followed by a facial combination of the above nano-aerogel with graphene film of high electrical conductivity,an extremely high electromagnetic interference shielding material(66.5 dB,2.06 mm thickness)with superior absorption performance of an average absorption-to-reflection(A/R)coefficient ratio of 25.4 and a low reflection bandwidth of 4.1 GHz(A/R ratio more than 10)was experimentally obtained in this work. 展开更多
关键词 Nano-pore size Heterogeneous interface Electromagnetic wave absorption Thermal infrared stealth Nano-aerogel
下载PDF
Role of heterogenous microstructure and deformation behavior in achieving superior strength-ductility synergy in zinc fabricated via laser powder bed fusion 被引量:1
17
作者 Zhi Dong Changjun Han +7 位作者 Yanzhe Zhao Jinmiao Huang Chenrong Ling Gaoling Hu Yunhui Wang Di Wang Changhui Song Yongqiang Yang 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2024年第4期225-245,共21页
Zinc(Zn)is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties.In this work,laser powder bed fusion(LPBF)additive manufacturin... Zinc(Zn)is considered a promising biodegradable metal for implant applications due to its appropriate degradability and favorable osteogenesis properties.In this work,laser powder bed fusion(LPBF)additive manufacturing was employed to fabricate pure Zn with a heterogeneous microstructure and exceptional strength-ductility synergy.An optimized processing window of LPBF was established for printing Zn samples with relative densities greater than 99%using a laser power range of 80∼90 W and a scanning speed of 900 mm s−1.The Zn sample printed with a power of 80 W at a speed of 900 mm s−1 exhibited a hierarchical heterogeneous microstructure consisting of millimeter-scale molten pool boundaries,micrometer-scale bimodal grains,and nanometer-scale pre-existing dislocations,due to rapid cooling rates and significant thermal gradients formed in the molten pools.The printed sample exhibited the highest ductility of∼12.1%among all reported LPBF-printed pure Zn to date with appreciable ultimate tensile strength(∼128.7 MPa).Such superior strength-ductility synergy can be attributed to the presence of multiple deformation mechanisms that are primarily governed by heterogeneous deformation-induced hardening resulting from the alternative arrangement of bimodal Zn grains with pre-existing dislocations.Additionally,continuous strain hardening was facilitated through the interactions between deformation twins,grains and dislocations as strain accumulated,further contributing to the superior strength-ductility synergy.These findings provide valuable insights into the deformation behavior and mechanisms underlying exceptional mechanical properties of LPBF-printed Zn and its alloys for implant applications. 展开更多
关键词 laser powder bed fusion ZINC heterogeneous microstructure bimodal grains strength-ductility synergy
下载PDF
Catalytic effect in lithium metal batteries: From heterogeneous catalyst to homogenous catalyst 被引量:1
18
作者 Haining Fan Xuan-Wen Gao +3 位作者 Hailong Xu Yichun Ding Shi-Xue Dou Wen-Bin Luo 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第3期305-326,I0008,共23页
Lithium metal batteries are regarded as prominent contenders to address the pressing needs owing to the high theoretical capacity.Toward the broader implementation,the primary obstacle lies in the intricate multi-elec... Lithium metal batteries are regarded as prominent contenders to address the pressing needs owing to the high theoretical capacity.Toward the broader implementation,the primary obstacle lies in the intricate multi-electron,multi-step redox reaction associated with sluggish conversion kinetics,subsequently giving rise to a cascade of parasitic issues.In order to smooth reaction kinetics,catalysts are widely introduced to accelerate reaction rate via modulating the energy barrier.Over past decades,a large amount of research has been devoted to the catalyst design and catalytic mechanism exploration,and thus the great progress in electrochemical performance has been realized.Therefore,it is necessary to make a comprehensive review toward key progress in catalyst design and future development pathway.In this review,the basic mechanism of lithium metal batteries is provided along with corresponding advantages and existing challenges detailly described.The main catalysts employed to accelerate cathode reaction with emphasis on their catalytic mechanism are summarized as well.Finally,the rational design and innovative direction toward efficient catalysts are suggested for future application in metal-sulfur/gas battery and beyond.This review is expected to drive and benefit future research on rational catalyst design with multi-parameter synergistic impacts on the activity and stability of next-generation metal battery,thus opening new avenue for sustainable solution to climate change,energy and environmental issues,and the potential industrial economy. 展开更多
关键词 Energy storage and conversion Metal battery Sulfur battery Air battery Catalytic effect Heterogeneous catalyst Homogeneous catalyst
下载PDF
Development of a convolutional neural network based geomechanical upscaling technique for heterogeneous geological reservoir 被引量:1
19
作者 Zhiwei Ma Xiaoyan Ou Bo Zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第6期2111-2125,共15页
Geomechanical assessment using coupled reservoir-geomechanical simulation is becoming increasingly important for analyzing the potential geomechanical risks in subsurface geological developments.However,a robust and e... Geomechanical assessment using coupled reservoir-geomechanical simulation is becoming increasingly important for analyzing the potential geomechanical risks in subsurface geological developments.However,a robust and efficient geomechanical upscaling technique for heterogeneous geological reservoirs is lacking to advance the applications of three-dimensional(3D)reservoir-scale geomechanical simulation considering detailed geological heterogeneities.Here,we develop convolutional neural network(CNN)proxies that reproduce the anisotropic nonlinear geomechanical response caused by lithological heterogeneity,and compute upscaled geomechanical properties from CNN proxies.The CNN proxies are trained using a large dataset of randomly generated spatially correlated sand-shale realizations as inputs and simulation results of their macroscopic geomechanical response as outputs.The trained CNN models can provide the upscaled shear strength(R^(2)>0.949),stress-strain behavior(R^(2)>0.925),and volumetric strain changes(R^(2)>0.958)that highly agree with the numerical simulation results while saving over two orders of magnitude of computational time.This is a major advantage in computing the upscaled geomechanical properties directly from geological realizations without the need to perform local numerical simulations to obtain the geomechanical response.The proposed CNN proxybased upscaling technique has the ability to(1)bridge the gap between the fine-scale geocellular models considering geological uncertainties and computationally efficient geomechanical models used to assess the geomechanical risks of large-scale subsurface development,and(2)improve the efficiency of numerical upscaling techniques that rely on local numerical simulations,leading to significantly increased computational time for uncertainty quantification using numerous geological realizations. 展开更多
关键词 Upscaling Lithological heterogeneity Convolutional neural network(CNN) Anisotropic shear strength Nonlinear stressestrain behavior
下载PDF
EVIDENCE OF ISOTOPIC SYSTEMATICS FROM CRUST AND MANTLE FOR CHEMICAL HETEROGENEITIES OF TERRANES 被引量:7
20
作者 朱炳泉 《Chinese Science Bulletin》 SCIE EI CAS 1991年第15期1279-1282,共4页
The extensive tracing of Nd, Sr and Pb isotopes has revealed that there exist high-degree heterogeneities in suboceanic mantle and mantle anomalies of the Southern Hemisphere on a large scale (DUPAL, high <sup>8... The extensive tracing of Nd, Sr and Pb isotopes has revealed that there exist high-degree heterogeneities in suboceanic mantle and mantle anomalies of the Southern Hemisphere on a large scale (DUPAL, high <sup>87</sup>Sr/<sup>86</sup>Sr, and HIMU, high μ value, i. e. <sup>238</sup> U/<sup>204</sup>pb). Recently, the isotopic tracing of the Cenozoic Volcanics from the continent of China has confirmed that there exists a general tendency that the subcontinental mantle of eastern China was en- 展开更多
关键词 CHEMICAL heterogeneities of TERRANES multi dimension space of ISOTOPIC SYSTEMATICS CRUST-MANTLE evolution.
原文传递
上一页 1 2 146 下一页 到第
使用帮助 返回顶部