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Earthquake Engineering and Engineering Vibration 2018年第1期17卷 103-124页

作者： Li Chong yuan Juyun yu Haitao yuan Yong Department of Geotechnical Engineering Tongji University Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji University State Key Laboratory for Disaster Reduction in Civil Engineering Tongji University

Discrete models such as the lumped parameter model and the finite element model are widely used in the solution of soil amplification of earthquakes. However, neither of the models will accurately estimate the natural frequencies of soil deposit, nor simulate a damping of frequency independence. This research develops a new discrete model for onedimensional viscoelastic response analysis of layered soil deposit based on the mode equivalence method. The new discrete model is a one-dimensional equivalent multi-degree-of-freedom（MDOF） system characterized by a series of concentrated masses, springs and dashpots with a special configuration. The dynamic response of the equivalent MDOF system is analytically derived and the physical parameters are formulated in terms of modal properties. The equivalent MDOF system is verified through a comparison of amplification functions with the available theoretical solutions. The appropriate number of degrees of freedom（DOFs） in the equivalent MDOF system is estimated. A comparative study of the equivalent MDOF system with the existing discrete models is performed. It is shown that the proposed equivalent MDOF system can exactly present the natural frequencies and the hysteretic damping of soil deposits and provide more accurate results with fewer DOFs.

关键词： ground response analysis MDOF system mode equivalence modal properties layered soil viscoelastic amplification

Ammonium-dependent regulation of ammonium transporter ZmAMT1s expression conferred by glutamine levels in roots of maize

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Journal of Integrative Agriculture 2022年第8期21卷 2413-2421页

作者： HUI Jing LIU Zhi duan Feng-ying ZHAO Yang LI Xue-lian AN Xia WU Xiang-yu yuan Li-xing College of Resources and Environmental Sciences China Agricultural UniversityBeijing 100193P.R.China

In maize,two root epidermis-expressed ammonium transporters ZmAMT1;1a and ZmAMT1;3 play major roles in highaffinity ammonium ***,the transcriptional regulation of ZmAMT1s in roots for ensuring optimal ammonium acquisition remains largely ***,using a split root system we showed that ZmAMT1;1a and ZmAMT1;3transcript levels were induced by localized ammonium supply to nitrogen-deficient *** enhanced expression of Zm AMT1s correlated with increases in ^(15)NH_(4)^(+)influx rates and tissue glutamine concentrations in *** ammonium was supplied together with methionine sulfoximine,an inhibitor of glutamine synthase,ammonium-induced expression of ZmAMT1s disappeared,suggesting that glutamine rather than ammonium itself regulated ZmAMT1s *** glutamine was supplied to nitrogen-deficient roots,expression levels of ZmAMT1s were enhanced,and negative feedback regulation could subsequently occur by supply of glutamine at a high ***,our results indicated an ammonium-dependent regulation of ZmAMT1s at transcript levels,and a dual role of glutamine was suggested in the regulation of ammonium uptake in maize roots.

关键词： ammonium transporter pH glutamine maize roots nitrogen transcriptional regulation

Low-Cycle Fatigue and Creep-Fatigue Behaviors of a Second-Generation Nickel-Based Single-Crystal Superalloy at 760℃

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Acta Metallurgica Sinica(English Letters) 2020年第10期33卷 1423-1432页

作者： Jian Zhang yuan-yuan Guo Mai Zhang Zhen-yu Yang yu-Shi Luo Beijing Institute of Aeronautical Materials Beijing 100095China School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China

Low-cycle fatigue(LCF)behaviors of a second-generation nickel-based single-crystal superalloys with[001]orientation at 760℃ have been *** strain amplitudes were introduced to investigate the creep-fatigue *** LCF life of none tensile holding(NTH)was higher than that of the 60-s tensile hold(TH)at any strain *** the strain amplitude was 0.7%,the stacking and cross-slip dislocations appeared together at the γ/γ’coherent microstructure in both TH and NTH *** the strain amplitude of 0.9%,plenty of the cross-slip dislocations appeared inγchannel and other dislocations were stacking at γ/γ’***,the SFs still appeared in γ’phase with 60-s TH which caused cyclic *** the strain amplitude increased up to 1.2%,the dislocations are piling up at the γ/γ’interfaces and cutting through the γ’phase in both TH and NTH tests,which caused cyclic *** influences of strain amplitude and holding time were *** stress response behaviors occurred in different loading *** surface characteristic and fracture mechanism were observed by scanning electron *** result is helpful for building the relationship of various blade fatigue failure modes,cyclic stress response and microstructure deformation under different strain amplitudes.

关键词： Low-cycle fatigue Cyclic stress response behavior Dislocation morphologies

Design and analyses of open-ended pipe piles in cohesionless soils

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Frontiers of Structural and Civil Engineering 2016年第1期10卷 22-29页

作者： yuan GUO Xiong (Bill) yu Department of Civil Engineering Case Western Reserve University 2104 Adelbert Road Bingham 260 Cleveland OH 44106-7201USA

Large open-ended pipe pile has been found to be advantageous for use in transportation projects. The current design method, however, is not adequately developed. To close this practice gap, this paper first summarized different design methods for open-ended pipe piles in sandy soils. A major factor for all the design codes is to properly account for the formation and effects of soil plug. The comparison indicates that there is a large variation in the base capacity evaluation among different methods due to the complex behaviors of soil plug. To close the knowledge gap, discrete element method （DEM） was used to simulate the soil plugging process and provide insight on the plugging mechanism. The simulation results show that the arching effect significantly increases the internal unit shear resistance along pipe piles. The porosity distribution and particle contact force distribution from DEM model indicate a large stress concentration occurs at the bottom of the soil plug. Besides, nearly 90% of the plug resistance is provided by the bottom half portion of the soil column. The soil-pile friction coefficient has a significant effect on the magnitude of plug resistance, with the major transition occurred for friction coefficient between 0.3 and 0.4.

关键词： open-ended pipe pile soil plug DEM base capacity

The ferroptosis activity is associated with neurological recovery following chronic compressive spinal cord injury

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Neural Regeneration Research 2023年第11期18卷 2482-2488页

作者： Zhengran yu Xing Cheng Wenxu Pan Cheng yu Yang duan Department of Spine Surgery Orthopedics Center of Guangdong Provincial People’s Hospital(Guangdong Academy of Medical Sciences)Southern Medical UniversityGuangzhouGuangdong ProvinceChina Department of Spine Surgery The First Affiliated HospitalSun Yat-sen UniversityGuangzhouGuangdong ProvinceChina Department of Gastroenterology Guangzhou Women and Children’s Medical CenterJinan UniversityGuangzhouGuangdong ProvinceChina Department of Spine Surgery Zhujiang HospitalSouthern Medical UniversityGuangzhouGuangdong ProvinceChina

Chronic compressive spinal cord injury in compressive cervical myelopathy conditions can lead to rapid neurological deterioration in the early phase,followed by partial self-recovery,and ultimately an equilibrium state of neurological *** is a crucial pathological process in many neurodegenerative diseases;however,its role in chro nic compressive spinal cord injury remains *** this study,we established a chronic compressive spinal cord injury rat model,which displayed its most severe behavioral and electrophysiological dysfunction at 4 wee ks and partial recovery at 8 weeks after *** RNA sequencing data identified enriched functional pathways,including ferroptosis,presynapse,and postsynaptic membrane activity at both 4 and 8 wee ks following chro nic compressive spinal co rd *** nsmission electron microscopy and malondialdehyde quantification assay confirmed that ferroptosis activity peaked at 4 weeks and was attenuated at 8 weeks after chronic *** ptosis activity was negatively correlated with behavioral ***,quantitative polymerase chain reaction,and western blotting showed that expression of the anti-ferroptosis molecules,glutathione peroxidase 4(GPX4) and MAF BZIP transcription factor G(MafG),in neuro ns was suppressed at 4 weeks and upregulated at 8 weeks following spinal co rd *** was a positive correlation between the expression of these two molecules,suggesting that they may work together to contribute to functional recovery following chronic compressive spinal cord *** conclusion,our study determined the genome-wide expression profile and fe rroptosis activity of a consistently compressed spinal cord at different time *** results showed that anti-fe rroptosis genes,specifically GPX4 and MafG,may be involved in spontaneous neurological recovery at 8 weeks of chronic compressive spinal cord *** findings contribute to a better understanding of t

关键词： chronic spinal cord compression compressive cervical myelopathy ferroptosis genome-wide transcriptome glutathione peroxidase 4(GPX4) MAF BZIP transcription factor G(MafG) neurological function

Evalution of Thermal Oxidative Degradation of Trimethylol-propane Trioleate by TG/DTA/DSC

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Journal of Wuhan University of Technology(Materials Science) 2021年第2期36卷 280-288页

作者： ZHAN Wen duan Haitao LI Xinxiang LI Jian yuan Chengqing Wuhan Research Institute of Materials Protection China Academy of Machinery Science and TechnologyWuhan 430030China School of Energy and Power Engineering Wuhan University of TechnologyWuhan 430063China

In order to evaluate the thermal oxidation degradation behavior of lubricant with different antioxidants,the thermal kinetics equation based on the anlyses of thermogravimetry(TG),differential thermal analysis(DTA),and differential scanning calorimetry(DSC)was established,respectively,to calculate the activation energy of lubricant thermal-oxidative *** thermal analyses of TG and DTA were employed to determine the thermal decomposition properties of ester oils trimethylolpropane trioleate(TMPTO)with butyl-octyl-diphenylamine/octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate/amine-phenol combination *** activation energy of the lubricating oil adding antioxidant is increased relative to the TMPTO base oil,and the order of activation energy are Ec(93.732 kJ·mol^(-1))>Ed(88.71 kJ·mol^(-1))>Eb(58.41 kJ·mol^(-1))>Ea(46.32 kJ·mol^(-1)).The experimental results show that octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate in TMPTO has favorable resistance to thermal oxidation and *** thermal analysis method of DSC accurately reflects the heat exchange of lubricant thermal-oxidative *** order of activation energy is calculated to ED(144.385 kJ·mol^(-1))>EC(110.05 kJ·mol^(-1))>EB(97.187 kJ·mol^(-1))>EA(66.02 kJ·mol^(-1)).It is illustrated that the amine-phenol combination antioxidant has the best thermal oxidation resistance,which is the same as what the oxidation onset temperature effected.

关键词： thermal oxidative degradation thermal kinetics antioxidants trimethylolpropane oleate

Synthesis and Characterization of a Novel Functional Biodegradable Copolymer-Poly(lactic acid-4-hydroxyproline-polyethylene glycol)

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Chinese Chemical Letters 2006年第8期17卷 1125-1128页

作者： Jiu Fang duan yu Bin ZHENG Department of Polymer Science Dalian University of Technology Dalian 116012

A series of poly（lactic acid-4-hydroxyproline-polyethylene glycol）（PLA-Hpr-PEG） copolymers were synthesized by direct melt copolymerization of D,L-lactic acid and 4-hydroxyproline with different feed amount of polyethylene glycol （PEG） 0.1%, 0.5%, 1% and 5%, respectively. The properties of these copolymers were characterized by using IR spectroscopy, proton nuclear magnetic resonance （1H-NMR） spectroscopy, gel permeation chromatography （GPC）, X-ray diffraction and differential scaning calorimetry （DSC）. PLA-Hpr-PEG are amorphous copolymers. Copolymers showed increasing water uptake capacity with increasing PEG percentage in the feed, which result in an increasing degradable rate in phosphate buffer solution （pH 7.4） at 37℃.

关键词： Lactic acid 4-hydroxyproline polyethylene glycol.

Trial application of the envelope method to the potential ambiguity problem

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Nuclear Science and Techniques 2024年第1期35卷 73-80页

作者： Li-yuan Hu yu-Shou Song Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering UniversityHarbin 150001China College of Nuclear Science and Technology Harbin Engineering UniversityHarbin 150001China Key Laboratory of Nuclear Safety and Advanced Nuclear Energy Technology Ministry of Industry and Information TechnologyHarbin 150001China

The optical potential ambiguity is a long-standing problem in the analysis of elastic scattering *** a specific collid-ing system,ambiguous potential families can lead to different behaviors in the nearside and farside scattering *** contrast,the envelope method can decompose the experimental data into two components with negative and positive deflection angles,***,a question arises as to whether the comparison between the calculated nearside(or farside)component and the derived positive-deflection-angle(or negative-deflection-angle)component can help analyze the potential ambiguity *** this study,we conducted a trial application of the envelope method to the potential ambiguity *** envelope method was improved by including uncertainties in the experimental *** colliding systems of 16O+28Si at 215.2 MeV and 12C+12C at 1016 MeV were considered in the *** each colliding system,the angular distribution experimental data were described nearly equally well by two potential sets,one of which is“surface transpar-ent”and the other is *** calculated angular distributions were decomposed into nearside and farside scattering *** the improved envelope method,the experimental data were decomposed into the positive-deflection-angle and negative-deflection-angle components,which were then compared with the calculated nearside and farside *** capability of the envelope method to analyze the potential ambiguities was also discussed.

关键词： Elastic scattering Optical potential ambiguities Envelope method Nearside/farside decomposition

Effect of antidepressants on body weight, ethology and tumor growth of human pancreatic carcinoma xenografts in nude mice

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World Journal of Gastroenterology 2008年第27期14卷 4377-4382页

作者： Lin Jia yuan-yuan Shang yu-yuan Li Department of Digestive Diseases Guangzhou Municipal First People's Hospital Guangzhou Medical College Guangzhou 510180 Guangdong Province China

AIM: To investigate the effects of mirtazapine and fluoxetine, representatives of the noradrenergic and specific serotonergic antidepressant (NaSSA) and se- lective serotonin reuptake inhibitor (SSRI) antidepres- sant respectively, on body weight, ingestive behavior, locomotor activity and tumor growth of human pancre- atic carcinoma xenografts in nude mice. METHODS: A subcutaneous xenograft model of hu- man pancreatic cancer cell line SW1990 was estab- lished in nude mice. The tumor-bearing mice were ran- domly divided into mirtazapine group [10 mg/(kg·d)], fluoxetine group [10 mg/(kg·d)] and control group (an equivalent normal saline solution) (7 mice in each group). Doses of all drugs were administered orally, once a day for 42 d. Tumor volume and body weight were measured biweekly. Food intake was recorded once a week. Locomotor activity was detected weekly using an open field test (OFT). RESULTS: Compared to the fluoxetine, mirtazapine significantly increased food intake from d 14 to 42 and attenuated the rate of weight loss from d 28 to 42 (t = 4.38, P < 0.05). Compared to the control group, food intake was significantly suppressed from d 21 to 42 and weight loss was promoted from d 35 to 42 in the fluoxetine group (t = 2.52, P < 0.05). There was a significant difference in body weight of the mice after removal of tumors among the three groups. The body weight of mice was the heaviest (13.66 ± 1.55 g) in the mirtazapine group and the lightest (11.39 ± 1.45 g) in the fluoxetine group (F(2,12) = 11.43, P < 0.01). The behavioral test on d 7 showed that the horizontal and vertical activities were significantly increased in the mirtazapine group compared with the fluoxetine and control groups (F(2,18) = 10.89, P < 0.01). These effects disappeared in the mirtazapine and fluoxetine groups during 2-6 wk. The grooming activity was higher in the mirtazapine group than in the fluoxetine group (10.1 ± 2.1 vs 7.1 ± 1.9 ) (t = 2.40, P < 0.05) in the second week. There was n

关键词： Pancreatic carcinoma Mirtazapine Fluoxetine Body weight Nude mice Locomotor activity Ethology

Covert communication with beamforming over MISO channels in the finite blocklength regime

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Science China(Information Sciences) 2021年第9期64卷 187-201页

作者： Xinchun yu yuan LUO Wen CHEN School of Electronic Information and Electrical Engineering Shanghai Jiao Tong University

This paper considers beamforming techniques for covert communication over multiple input single output(MISO) channels with finite blocklength. We first show that the optimal input distribution for covert communication over complex Gaussian channels is circular symmetric complex Gaussian. By reviewing our previous results on the throughput of Gaussian random coding over additive white Gaussian noise(AWGN) channels, the achievability and converse bounds on the attainable throughput over MISO channels are analyzed. Then, the optimal beamforming strategies and their relationship with the transmitting power are thoroughly investigated in a variety of situations in terms of several types of channel state information available at both ends of the system. We reveal the fact that the maximal allowable transmit power is not constrained by covertness requirement when there is full channel information of the adversary, while there is an upper bound of the transmit power which is based on beamforming and an outage-based covertness criterion if there is only partial channel information of the adversary. Finally, numerical results are presented to show that the throughput of covert communication can be increased notably by adopting a proper beamforming strategy in MISO channels in comparison with the single antenna case.

关键词： beamforming circular symmetric complex Gaussian covert communication MISO channels power control