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Shear behavior of intact granite under thermo-mechanical coupling and three-dimensional morphology of shear-formed fractures

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第3期15卷 523-537页

作者： Bing Chen Baotang Shen Haiyang Jiang State Key Laboratory of Mining Disaster Prevention and Control Shandong University of Science and TechnologyQingdao266590China CSIRO Mineral Resources Queensland Centre for Advanced Technologies1 Technology CourtPullenvaleQLD4069Australia No.1 Institute of Geology and Mineral Resource Exploration of Shandong Province Jinan250010China College of New Energy and Environment Jilin UniversityChangchun130012China

The shear failure of intact rock under thermo-mechanical(TM)coupling conditions is common,such as in enhanced geothermal mining and deep mine construction.Under the effect of a continuous engineering disturbance,shear-formed fractures are prone to secondary instability,posing a severe threat to deep engineering.Although numerous studies regarding three-dimensional(3D)morphologies of fracture surfaces have been conducted,the understanding of shear-formed fractures under TM coupling conditions is limited.In this study,direct shear tests of intact granite under various TM coupling conditions were conducted,followed by 3D laser scanning tests of shear-formed fractures.Test results demonstrated that the peak shear strength of intact granite is positively correlated with the normal stress,whereas it is negatively correlated with the temperature.The internal friction angle and cohesion of intact granite significantly decrease with an increase in the temperature.The anisotropy,roughness value,and height of the asperities on the fracture surfaces are reduced as the normal stress increases,whereas their variation trends are the opposite as the temperature increases.The macroscopic failure mode of intact granite under TM coupling conditions is dominated by mixed tensileeshear and shear failures.As the normal stress increases,intragranular fractures are developed ranging from a local to a global distribution,and the macroscopic failure mode of intact granite changes from mixed tensileeshear to shear failure.Finally,3D morphological characteristics of the asperities on the shear-formed fracture surfaces were analyzed,and a quadrangular pyramid conceptual model representing these asperities was proposed and sufficiently verified.

关键词： Thermo-mechanical(TM)coupling Peak shear strength Three-dimensional(3D)morphological characterization Failure mode Quadrangular pyramid model

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Impacts of oxygen deficiency on embryo life-history traits of migratory locust Locusta migratoria from low and high altitudes

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Insect Science 2023年第3期30卷 867-879页

作者： Xianliang Huang Qianli Du Lijing Wang Bing Chen School of Life Science Institutes of Life Science and Green DevelopmentHebei UniversityBaodingHebei ProvinceChina Kenli Municipal Bureau of Agriculture and Rural Affairs DongyingShandong ProvinceChina

Hypoxia challenges aerobic organisms in numerous environments,and hypoxic conditions may become more severe under future climate-change scenarios.The impact of hypoxia on the development of terrestrial insect embryos is not well understood.Here,to address this gap,embryonic life-history traits of migratory locust Locusta migratoria from low-altitude and high-altitude regions were compared under 2 oxygen levels:normoxia(i.e.,21 kPa oxygen partial pressure and mild hypoxia(i.e.,10 kPa oxygen partial pressure).Our results demonstrated that,whether reared under normoxia or mild hypoxia,L.migratoria from high-altitude populations had longer developmental times,reduced weight,and lower mean relative growth rate as compared with those from low-altitude populations.When transferred from normoxia to mild hypoxia,nearly all the tested lifehistory traits presented significant negative changes in the low-altitude populations,but not in the high-altitude populations.The factor'strain'alone explained 18.26%-54.59%of the total variation for traits,suggesting that the phenotypic differences between L.migratoria populations from the 2 altitudes could be driven by genetic variation.Significant genetic correlations were found between life-history traits,and most of these showed differentiation between the 2 altitudinal gradients.G-matrix comparisons showed significant structural differences between L.migratoria from the 2 regions,as well as several negative covariances(i.e.,trade-offs)between traits in the low-altitude populations.Overall,our study provides clear evidence that evolutionary divergence of embryonic traits between L.migratoria populations from different altitudes has occurred.

关键词： embryo life-history traits Locusta migratoria oxygen deficiency population divergence

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Clinical mycophenolic acid monitoring in liver transplant recipients

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World Journal of Gastroenterology 2014年第31期20卷 10715-10728页

作者： Hao chen Bing Chen Center of Organ Transplantation and Department of Surgery Ruijin Hospital Shanghai Jiao Tong University School of Medicine Institute of Clinical Pharmacology Ruijin Hospital Shanghai Jiao Tong University School of Medicine

In liver transplantation, the efficacy of mycophenolate mofetil(MMF) has been confirmed in clinical trials and studies. However, therapeutic drug monitoring for mycophenolic acid(MPA) has not been fully accepted in liver transplantation as no long-term prospective study of concentration controlled vs fixed-dose prescribing of MMF has been done. This review addressed MPA measurement, pharmacokinetic variability and reasons of this variation, exposure related to acute rejection and MMF-associated side effects in liver transplant recipients. Limited sampling strategies to predict MPA area under the concentration-time curve have also been described, and the value of clinical use needs to be investigated in future. The published data suggested that a fixed-dosage MMF regimen might not be suitable and monitoring of MPA exposure seems helpful in various clinical settings of liver transplantation.

关键词： Mycophenolate mofetil Mycophenolic acid Pharmacoki

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Dynamic expression of Slit1–3 and Robo1–2 in the mouse peripheral nervous system after injury

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Neural Regeneration Research 2020年第5期15卷 948-958页

作者： Bing Chen Lauren Carr Xin-Peng Dun Department of Neurology The Affiliated Huaian No.1 People’s Hospital of Nanjing Medical UniversityHuai’anJiangsu ProvinceChina Plymouth University Peninsula Schools of Medicine and Dentistry PlymouthUK The Co-innovation Center of Neuroregeneration Nantong UniversityNantongJiangsu ProvinceChina

The Slit family of axon guidance cues act as repulsive molecules for precise axon pathfinding and neuronal migration during nervous system development through interactions with specific Robo receptors.Although we previously reported that Slit1–3 and their receptors Robo1 and Robo2 are highly expressed in the adult mouse peripheral nervous system,how this expression changes after injury has not been well studied.Herein,we constructed a peripheral nerve injury mouse model by transecting the right sciatic nerve.At 14 days after injury,quantitative real-time polymerase chain reaction was used to detect mRNA expression of Slit1–3 and Robo1–2 in L4–5 spinal cord and dorsal root ganglia,as well as the sciatic nerve.Immunohistochemical analysis was performed to examine Slit1–3,Robo1–2,neurofilament heavy chain,F4/80,and vimentin in L4–5 spinal cord,L4 dorsal root ganglia,and the sciatic nerve.Co-expression of Slit1–3 and Robo1–2 in L4 dorsal root ganglia was detected by in situ hybridization.In addition,Slit1–3 and Robo1–2 protein expression in L4–5 spinal cord,L4 dorsal root ganglia,and sciatic nerve were detected by western blot assay.The results showed no significant changes of Slit1–3 or Robo1–2 mRNA expression in the spinal cord within 14 days after injury.In the dorsal root ganglion,Slit1–3 and Robo1–2 mRNA expression were initially downregulated within 4 days after injury;however,Robo1–2 mRNA expression returned to the control level,while Slit1–3 mRNA expression remained upregulated during regeneration from 4–14 days after injury.In the sciatic nerve,Slit1–3 and their receptors Robo1–2 were all expressed in the proximal nerve stump;however,Slit1,Slit2,and Robo2 were barely detectable in the nerve bridge and distal nerve stump within 14 days after injury.Slit3 was highly ex-pressed in macrophages surrounding the nerve bridge and slightly downregulated in the distal nerve stump within 14 days after injury.Robo1 was upregulated in vimentin-positive cells and migrating Schwann cells inside the nerve bridge.Robo1 was a

关键词： dorsal root ganglion nerve regeneration neural regeneration peripheral nerve Robo 1 Robo 2 sciatic nerve Slit1 Slit2 Slit3

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Modification of nanoparticles for the strength enhancing of cementstabilized dredged sludge

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第3期13卷 694-704页

作者： Lei Lang Bing Chen Haijuan Duan State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghaiChina Shanghai Key Laboratory for Digital Maintenance of Buildings and Infrastructure Department of Civil EngineeringShanghai Jiao Tong UniversityShanghaiChina

This paper investigates the effectiveness of nano-modification on the strength enhancement of cementstabilized dredged sludge(CDS).Three types of nanoparticles including nano-SiO2(NS),nano-Al2O3(NA)and nano-MgO(NM)were used as cement admixtures for dredged sludge stabilization.Effects of single nanoparticle content,mass ratio of composite nanoparticles and curing time on the strength development of CDS were evaluated via a series of unconfined compressive strength(UCS)tests.The pH evolutions of CDS caused by nanoparticles were also examined by a range of pH tests.Furthermore,micromechanisms reflecting the strength evolutions were analyzed by performing scanning electron microscopy(SEM)and X-ray diffraction(XRD)tests.The results indicated that adding nanoparticles can significantly improve the UCS of CDS.For single nano-modification,the optimum contents of NS,NA and NM were 4%e6%,6%and 8%,which can increase the 7-and 28-d UCSs of CDS by 38%and 50%,17%and 35%,65%and 67%,respectively.Compared with single nano-modification,composite nano-modifications were more effective in improving the strength gain of CDS.The optimum mass ratios of composite nanoparticles,namely NS/NA,NS/NM and NA/NM,were 9/1,3/7 and 3/7,respectively.Based on the strength growth rate,the composite nanoparticles with NS/NM of 3/7 were highly recommended.The addition of nanoparticles obviously affected the pH evolution of CDS,which was mainly determined by the difference of OHproduction and consumption inside nano-modified CDS.The microstructural analysis revealed that C-S-H and C-A-H gels are the main cementitious products,and the addition of nanoparticles can obviously contribute to a denser and more homogenous microstructure of CDS.

关键词： Cement-stabilized dredged sludge(CDS) Nano-modification Strength development pH level Microstructure

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Stability of computed tomography densitometry in patients with otosclerosis:a two-year follow-up

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Journal of Otology 2022年第1期17卷 39-45页

作者： Yanqing Fang Wei chen Liu-Jie Ren Sebastian Kiehn Yilai Shu Bing Chen ENT Institute and Otorhinolaryngology Department of the Affiliated Eye and ENT Hospital State Key Laboratory of Medical NeurobiologyFudan UniversityShanghai200031China NHC Key Laboratory of Hearing Medicine Fudan UniversityShanghai200031PR China Department of Radiology Eye and ENT HospitalFudan UniversityShanghai200031China Laryngeal Physiology Laboratory University of Wisconsin e MadisonMadisonWIUnited States Institutes of Biomedical Sciences Fudan UniversityNO.83 Fenyang RoadXuhui DistrictShanghai200031China

Objectives:To quantify the progression of otosclerosis in the unoperated ear between two stapedotomy procedures for patients with bilateral otosclerosis which can help to determine whether a HRCT scan should be re-performed before the second surgery for patients who already received HRCT imaging before the initial surgery.Methods:35 patients who underwent bilateral stapedotomy were included.Two rounds of HRCT examination and audiometry were performed at the time of the first surgery and second surgery on the ear that was not operated on during the initial surgery.The relationship between the changes in HRCT densitometry and audiometry over time was analyzed.Results:The second round of HRCT did not add significant information about the changes to the otosclerosis lesions in either the imaging diagnosis or the HRCT density values except for small changes in the HRCT densitometry readings at the area anterior to the inner auditory(P=0.01).While the changes in HRCT manifestation are small,changes near the fissula ante fenestram(FAF)were still positively correlated with the air bone gap(ABG)of patients(p=0.031,r=0.388).Conclusions:The progression of lesions in otosclerosis is slow resulting in small and insignificant changes to the HRCT features.Therefore,a repeat HRCT evaluations prior to surgery is not necessary for patients who have had a previous HRCT evaluation within 2 years of the operation.The small changes in HRCT manifestation near the FAF were still correlated with negative effects on the ABG which could cause worsened hearing thresholds over this timeframe。

关键词： Otosclerosis Fissula ante fenestram(FAF) High reconstruction-computed tomography (HRCT) Auditory CT densitometry

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3D morphology and formation mechanism of fractures developed by true triaxial stress

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International Journal of Mining Science and Technology 2022年第6期32卷 1273-1284页

作者： Bing Chen Baotang Shen Shichuan Zhang Yangyang Li Haiyang Jiang State Key Laboratory of Mining Disaster Prevention and Control Co-founded Shandong University of Science and TechnologyQingdao 266590China CSIRO Mineral Resources Queensland 4069Australia No.1 Institute of Geology and Mineral Resource Exploration of Shandong Province Jinan 250010China College of New Energy and Environment Jilin UniversityChangchun 130012China

As main part of underground rock mass,the three-dimensional(3D)morphology of natural fractures plays an important role in rock mass stability.Based on previous studies on 3D morphology,this study probes into the law and mechanism regarding the influence of the confining pressure constraints on 3D morphological features of natural fractures.First,fracture surfaces were obtained by true triaxial compression test and 3D laser scanning.Then 3D morphological parameters of fractures were calculated by using Grasselli’s model.The results show that the failure mode of granites developed by true triaxial stress can be categorized into tension failure and shear failure.Based on the spatial position of fractures,they can be divided into tension fracture surface,S-1 shear fracture surface,and S-2 shear fracture surface.Micro-failure of the tension fracture surface is dominated by mainly intergranular fracture;the maximum height of asperities on the fracture surface and the 3D roughness of fracture surfaces are influenced by σ_(3) only and they are greater than those of shear fracture surfaces,a lower overall uniformity than tension fracture surface.S-1 shear fracture surface and S-2 shear fracture surface are dominated by intragranular and intergranular coupling fracture.The maximum height of asperities on the fracture surface and 3D roughness of fracture surface are affected by σ_(1),σ_(2),and σ_(3).With the increase of σ_(2) or σ_(3),the cutting off of asperities on the fracture surface becomes more common,the maximum height of asperities and 3D roughness of fracture surface further decrease,and the overall uniformity gets further improved.The experimental results are favorable for selecting technical parameters of enhanced geothermal development and the safety of underground mine engineering.

关键词： True triaxial stress Failure mode Fracture angle 3D morphology Micro-fracture

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Minimum Time Extrema Estimation for Large-Scale Radio-Frequency Identification Systems

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Journal of Computer Science & Technology 2020年第5期35卷 1099-1114页

作者： Xiao-Jun Zhu Li-Jie Xu Xiao-bing Wu Bing Chen College of Computer Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 211106China Jiangsu Key Laboratory of Dig Data Security and Intelligent Processing Nanjing University of Posts and TelecommunicationsNanjing 210049China Wireless Research Centre University of CanterburyChristchurch 8041New Zealand

We consider the extrema estimation problem in large-scale radio-frequency identification(RFID)systems,where there are thousands of tags and each tag contains a finite value.The objective is to design an extrema estimation protocol with the minimum execution time.Because the standard binary search protocol wastes much time due to inter-frame overhead,we propose a parameterized protocol and treat the number of slots in a frame as an unknown parameter.We formulate the problem and show how to find the best parameter to minimize the worst-case execution time.Finally,we propose two rules to further reduce the execution time.The first is to find and remove redundant frames.The second is to concatenate a frame from minimum value estimation with a frame from maximum value estimation to reduce the total number of frames.Simulations show that,in a typical scenario,the proposed protocol reduces execution time by 79%compared with the standard binary search protocol.

关键词： radio-frequency identification(RFID)system maximum value estimation minimum value estimation time efficient protocol

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2D all-organic perovskites refine flexible electronics

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Science China Materials 2024年

作者： Wei Zhou Bing Chen Nanjing University of Posts and Telecommunications College of Electronic and Optical Engineering and College of Flexible Electronics (Future Technology)

Recent years have witnessed a paradigm shift with the advent of perovskites, a class of materials with a distinct CaTiO3-type crystalline structure that show remarkable promise across a wide array of applications, including photovoltaics, photodetectors,lighting, lasers, and so forth. Among them, the development of two-dimensional (2D) perovskites has garnered significant attention due to their tunable structures (mainly Dion-Jacobson and Ruddlesden-Popper structures) and enhanced stability in comparison with their 3D counterparts [1].

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A Compensation Controller Based on a Nonlinear Wavelet Neural Network for Continuous Material Processing Operations

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Computers, Materials & Continua 2019年第7期61卷 379-397页

作者： chen Shen Youping chen Bing Chen Jingming Xie School of Mechanical Science and Engineering Huazhong University of Science and TechnologyWuhanChina

Continuous material processing operations like printing and textiles manufacturing are conducted under highly variable conditions due to changes in the environment and/or in the materials being processed.As such,the processing parameters require robust real-time adjustment appropriate to the conditions of a nonlinear system.This paper addresses this issue by presenting a hybrid feedforward-feedback nonlinear model predictive controller for continuous material processing operations.The adaptive feedback control strategy of the controller augments the standard feedforward control to ensure improved robustness and compensation for environmental disturbances and/or parameter uncertainties.Thus,the controller can reduce the need for manual adjustments.The controller applies nonlinear generalized predictive control to generate an adaptive control signal for attaining robust performance.A wavelet-based neural network model is adopted as the prediction model with high prediction precision and time-frequency localization characteristics.Online training is utilized to predict uncertain system dynamics by tuning the wavelet neural network parameters and the controller parameters adaptively.The performance of the controller algorithm is verified by both simulation,and in a real-time practical application involving a single-input single-output double-zone sliver drafting system used in textiles manufacturing.Both the simulation and practical results demonstrate an excellent control performance in terms of the mean thickness and coefficient of variation of output slivers,which verifies the effectiveness of this approach in improving the long-term uniformity of slivers.

关键词： Continuous material processing wavelet neural network(WNN) nonlinear generalized predictive control(NGPC) auto-leveling system

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