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The Year-scale X-Ray Variations in the Core of M87

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Research in Astronomy and Astrophysics 2023年第6期23卷 203-211页

作者： yu-Lin cheng Fei Xiang Heng yu Shu-Mei Jia Xiang-Hua Li cheng-Kui Li Yong Chen Wen-cheng Feng Department of Astronomy Yunnan UniversityKunming 650091China Department of Astronomy Beijing Normal UniversityBeijing 100875China Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Department of Physics and Institute of Theoretical Physics Nanjing Normal UniversityNanjing 210023China

The analysis of light variation of M87 can help us understand the disk *** the past decade,M87 has experienced several short-term light variabilities related to *** also find that there are year-scale X-ray variations in the core of *** light variability properties are similar to *** re-analyzing 56Chandra observations from 2007 to 2019,we distinguish the“non-flaring state”from“flaring state”in the light *** removing flaring state data,we identify four gas clumps in the nucleus and all of them can be well fitted by the clumpy-ADAF *** average mass accretion rate is~0.16M⊙yr^(-1).We analyze the photon index(Γ)-flux(2-10 keV)correlation between the non-flaring state and flaring *** the non-flaring states,the flux is inversely proportional to the photon *** the flaring states,we find no obvious correlation between the two *** addition,we find that the flare always occurs at a high mass accretion rate,and after the luminosity of the flare reaches the peak,it will be accompanied by a sudden decrease in *** results can be explained as that the energy released by magnetic reconnection destroys the structure of the accretion disk,thus the luminosity decreases rapidly and returns to normal levels thereafter.

关键词： X-rays:galaxies galaxies:clusters:individual(M87) accretion accretion disks

Small molecules for mesenchymal stem cell fate determination

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World Journal of Stem Cells 2019年第12期11卷 1084-1103页

作者： yu-Hao cheng Jing-cheng Dong Qin Bian Institute for Cell Engineering Johns Hopkins University School of MedicineBaltimoreMD 21205United States Department of Integrative Medicine Huashan HospitalFudan UniversityShanghai 200040China

Mesenchymal stem cells(MSCs)are adult stem cells harboring self-renewal and multilineage differentiation potential that are capable of differentiating into osteoblasts,adipocytes,or chondrocytes in vitro,and regulating the bone marrow microenvironment and adipose tissue remodeling in *** process of fate determination is initiated by signaling molecules that drive MSCs into a specific *** of MSC fate determination leads to different bone and adipose tissue-related diseases,including aging,osteoporosis,and insulin *** progress has been made in recent years in discovering small molecules and their underlying mechanisms control the cell fate of MSCs both in vitro and in *** this review,we summarize recent findings in applying small molecules to the trilineage commitment of MSCs,for instance,genistein,medicarpin,and icariin for the osteogenic cell fate commitment;isorhamnetin,risedronate,and arctigenin for pro-adipogenesis;and atractylenolides and dihydroartemisinin for chondrogenic fate *** highlight the underlying mechanisms,including direct regulation,epigenetic modification,and post-translational modification of signaling molecules in the AMPK,MAPK,Notch,PI3K/AKT,Hedgehog signaling pathways *** discuss the small molecules that are currently being studied in clinical *** target-based manipulation of lineage-specific commitment by small molecules offers substantial insights into bone marrow microenvironment regulation,adipose tissue homeostasis,and therapeutic strategies for MSC-related diseases.

关键词： Mesenchymal stem cell Mesenchymal stromal cell Cell fate determination Small molecules Natural compounds Signaling pathways

Long-term mechanical behavior and characteristics of cemented tailings backfill through impact loading

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International Journal of Minerals,Metallurgy and Materials 2020年第2期27卷 140-151页

作者： yu-ye Tan Elmo Davide yu-cheng Zhou Wei-dong Song Xiang Meng Key Laboratory of High-Efficient Mining and Safety of Metal Mines(Ministry of Education of China) University of Science and Technology BeijingBeijing 100083China School of Civil and Resources Engineering University of Science and Technology BeijingBeijing 100083China Norman B.Keevil Institute of Mining Engineering Applied Science SchoolUniversity of British ColumbiaVancouverBC Canada V6T 1Z4

Cemented tailings backfill(CTB)structures are important components of underground mine *** is important to investigate the characteristics and dynamic behavior of CTB materials because they are susceptible to disturbance by dynamic loading,such as excavation and *** this study,the authors present the results of a series of Split-Hopkinson pressure bar(SHPB)single and cyclic impact loading tests on CTB specimens to investigate the long-term dynamic mechanical properties of *** stress-strain relationship,dynamic strength,and dynamic failure characteristics of CTB specimens are analyzed and discussed to provide valuable conclusions that will improve our knowledge of CTB long-term mechanical behavior and *** instance,the dynamic peak stress under cyclic impact loading is approximately twice that under single impact loading,and the CTB specimens are less prone to fracture when cyclically *** findings and conclusions can provide a new set of references for the stability analysis of CTB materials and help guide mine designers in reducing the amount of binding agents and the associated mining cost.

关键词： cyclic impact loading cemented tailings backfill dynamic mechanical properties Split–Hopkinson pressure bar dynamic peak stress

Effects of solution treatment on mechanical properties and microstructures of Al-Li-Cu-Mg-Ag alloy

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Journal of Central South University 2013年第8期20卷 2083-2089页

作者： yu cheng YIN Deng-feng ZHENG Feng yu Xin-xiang School of Materials Science and Engineering Central South University Changsha 410083 China Key Laboratory of Nonferrous Materials of Ministry of Education (Central South University) Changsha 410083 China

Mechanical properties and microstructures of Al-Li-Cu-Mg-Ag alloy after solution treatments were investigated by means of optical microscopy （OM）, tensile test, hardness measurement and electrical conductivity test, differential scanning calorimetric （DSC）, energy dispersive X-ray （EDX）, scanning electron microscopy （SEM） and transition electron microscopy （TEM）, respectively The results show that both tensile strength and hardness increase first and then decrease with temperature at constant holding time of 30 min with maximum strength and hardness appearing at 520 ℃. Tensile strength, hardness and elongation of samples treated at 520 ℃ for 30 min are 566 MPa （σb）, 512 MPa （σ0.2）, HB 148 and 8.23% （δ）, respectively. There are certain amount of fine T1 （AI2CuLi） phase dispersing among AI substrates according to TEM images. This may result in mixed fracture morphology with trans-granular and inter-granular delamination cracks observed in SEM images.

关键词： Al-Li-Cu-Mg-Ag alloy solution treatment microstructure mechanical properties

The research of DPA attacks against AES implementations

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The Journal of China Universities of Posts and Telecommunications 2008年第4期15卷 101-106页

作者： HAN yu ZOU Xue-cheng LIU Zheng-lin CHEN Yi-cheng Department of Electronic Science and Technology Huazhong University of Science and Technology Wuhan 430074 China

This article examines vulnerabilities to power analysis attacks between software and hardware implementations of cryptographic algorithms. Representative platforms including an Atmel 89S8252 8-bit processor and a 0.25 um 1.8 v standard cell circuit are proposed to implement the advance encryption standard （AES）. A simulation-based experimental environment is built to acquire power data, and single-bit differential power analysis （DPA）, and multi-bit DPA and correlation power analysis （CPA） attacks are conducted on two implementations respectively. The experimental results show that the hardware implementation has less data-dependent power leakages to resist power attacks. Furthermore, an improved DPA approach is proposed. It adopts hamming distance of intermediate results as power model and arranges plaintext inputs to differentiate power traces to the maximal probability. Compared with the original power attacks, our improved DPA performs a successful attack on AES hardware implementations with acceptable power measurements and fewer computations.

关键词： AES implementation side-channel leakage DPA CPA power model power trace

The phylogenetic relationships of introduced Aphelinus （Hymenoptera： Aphelinidae）, biological control agents of the Russian wheat aphid （Homoptera： Aphididae）

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Insect Science 2009年第3期16卷 277-285页

作者： yu cheng Zhu Quentin Q. Fang USDA-ARS-JWDSRC Stoneville MS 38776 Department of Biology Georgia Southern University Statesboro GA 30460 USA

Several species of Aphelinus have been introduced to the US from the Old World for biological control of the Russian wheat aphid, Diuraphis noxia （Modvilko）. Reproductive incompatibility has been observed among populations collected from different geographic areas. We examined whether or not the reproductive incompatibility between strains of A. asychis was caused by distant phylogenetic relationships. Ribosomal DNA sequences of internal transcribed spacers 2 （ITS2） were analyzed in several species of Aphelinus collected from multiple sites of Europe and Asia. Yhe phylogenetic analysis showed that strains within the species A. albipodus and A. asychis are not monophyletic, and two clearly divergent clades were revealed among sequenced samples. Our results suggest that the reproductive incompatibility between three exotic strains ofA. asychis was more likely caused by divergence of phylogeny than by symbiotic bacteria.

关键词： Aphelinus Aphidius ITS molecular systematics phylogeny rDNA

Plant phenolics mediated bottom-up effects of elevated CO2 on Acyrthosiphon pisum and its parasitoid Aphidius avenae

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Insect Science 2020年第1期27卷 170-184页

作者： Hong-yu Yan Hong-Gang Guo yu-cheng Sun Feng Ge State Key Laboratory of Integrated Management of Pest and Rodents Institute of ZoologyChinese Academy of SciencesBeijingChina University of Chinese Academy of Sciences BeijingChina

Elevated concentrations of atmospheric CO2 can alter plant secondary metabolites,which play important roles in the interactions among plants,herbivorous insects and natural ***,few studies have examined the cascading effects of host plant secondary metabolites on tri-trophic interactions under elevated CO2(eCO2).In this study,we determined the effects of eCO2 on the growth and foliar phenolics of Medicago truncatula and the cascading effects on two color genotypes oiAcyrthosiphon pisum(pink ***)and their parasitoid Aphidius avenae in the field open-top *** results showed that eCO2 increased photosynthetic rate,nodule number,yield and the total phenolic content of ***2 had contrasting effects on two genotypes of ***;the green genotype demonstrated increased population abundance,fecundity,growth and feeding efficiency,while the pink genotype showed decreased fitness and these were closely associated with the foliar genstein ***,eCO2 decreased the parasitic rate of *** independent of aphid ***2 prolonged the emergence time and reduced the emergence rate and percentage of females when associated with the green genotype,but little difference,except for increased percentage of females,was observed in *** under eCO2 when associated with the pink genotype,indicating that parasitoids can perceive and discriminate the qualities of aphid *** concluded that eCO2 altered plant phenolics and thus the performance of aphids and *** results indicate that plant phenolics vary by different abiotic and biotic stimuli and could potentially deliver the cascading effects of eCO2 to the higher trophic *** results also suggest that the green genotype is expected to perform better in future eCO2 because of decreased plant resistance after its infestation and decreased parasitic rate.

关键词： Acyrthosiphon pisum:Aphidius avenae elevated CO2 Medicago truncatula' phenolics tri-trophic level

LES method of the tip clearance vortex cavitation in a propelling pump with special emphasis on the cavitation-vortex interaction

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Journal of Hydrodynamics 2020年第6期32卷 1212-1216页

作者： cheng-zao Han Shun Xu Huai-yu cheng Bin Ji Zhi-yuan Zhang State Key Lab of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China Marine Design and Research Institute of China Shanghai200011China

The turbulent cavitating flow around the propelling pump tip clearance is numerically simulated using the large eddy simulation(LES)method coupled with the Zwart-Gerber-Belamri(ZGB)cavitation model to investigate the cavitation-vortex interaction *** calculated cavitation structures around the blades are in a remarkable agreement with the experimental *** distributions of the tip clearance vortex under two cavitation conditions are obtained and *** results show that the cavitation development enhances the vorticity generation and the flow unsteadiness around the tip clearance of a propelling *** are basically located around the cavitation areas,particularly in the tip clearance region,during the *** relative vorticity transport equation is applied for the cavitating turbulent flows and it is further indicated that the vortex stretching term makes the main contribution in the vortex production,and the baroclinic torque and dilation terms are important source terms for the vorticity generation in the cavitating *** addition,the viscous diffusion term and the Coriolis force term are significant in modifying the vorticity field inside the blade tip clearance.

关键词： Tip-clearance cavitation propelling pump large eddy simulation(LES) vorticity transport equation

Adipose-derived mesenchymal stem cells accelerate nerve regeneration and functional recovery in a rat model of recurrent laryngeal nerve injury

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Neural Regeneration Research 2017年第9期12卷 1544-1550页

作者： yun Li Wen Xu Li-yu cheng Department of Otorhinolaryngology-Head Neck Surgery Beijing Tong Ren Hospital Capital Medical University Key Laboratory of Otorhinolaryngology-Head Neck Surgery Ministry of Education

Medialization thyroplasty or injection laryngoplasty for unilateral vocal fold paralysis cannot restore mobility of the vocal fold. Recent studies have shown that transplantation of mesenchymal stem cells is effective in the repair of nerve injuries. This study investigated wheth- er adipose-derived stem celt transplantation could repair recurrent laryngeal nerve injury. Rat models of recurrent laryngeal nerve injury were established by crushing with micro forceps. Adipose-derived mesenchymal stem cells （ADSCs; 8 ×105） or differentiated Schwann-like adipose-derived mesenchymal stem cells （dADSCs; 8×105） or extracellular matrix were injected at the site of injury. At 2, 4 and 6 weeks post-surgery, a higher density of myelinated nerve fiber, thicker myelin sheath, improved vocal fold movement, better recovery of nerve conduction capacity and reduced thyroarytenoid muscle atrophy were found in ADSCs and dADSCs groups compared with the extracellu- lar matrix group. The effects were more pronounced in the ADSCs group than in the dADSCs group. These experimental results indicated that ADSCs transplantation could be an early interventional strategy to promote regeneration after recurrent laryngeal nerve injury.

关键词： nerve regeneration mesenchymal stem cell transplantation adipose-derived mesenchymal stem cells recurrent laryngeal nerve larynx nerve injury functional recovery vocal fold cell differentiation neural regeneration