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Effects of hypoxia on the biological behavior of MSCs seeded in demineralized bone scaffolds with different stiffness

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Acta Mechanica Sinica 2019年第2期35卷 309-320页

作者： yuanyuan Sun Guobao Chen Yonggang Lv Key Laboratory of Biorheological Science and Technology (Chongqing University) Ministry of Education Bioengineering College Chongqing University Chongqing 400044 China Mechanobiology and Regenerative Medicine Laboratory Bioengineering College Chongqing University Chongqing 400044 China

Matrix stiffness has been demonstrated in many studies to adjust the biological behaviors of mesenchymal stem cells (MSCs). However, in the initial phase of bone restore, MSCs will encounter a hypoxic microenvironment. Studying the connection existing between the matrix stiffness and biological behavior of MSCs under hypoxic condition can better simulate the microenvironment at the prime period of bone repairment. In this work, three-dimensional (3D) decalcified bone scaffolds with diverse stiffness (high stiffness (66.06 ± 27.83) MPa, medium stiffness (26.90 ± 13.16) MPa, and low stiffness (0.67 ± 0.14) MPa) but same microstructure have been prepared by controlling decalcification time. In addition, the decellularized bone scaffold was regard as control group and its stiffness was (230.93 ± 72.65) MPa. The viability, proliferation, infiltration, and osteogenic differentiation of MSCs seeded into these 3D demineralized bone scaffolds were systematically investigated under 100 μM CoCl2-simulated hypoxic and normoxic environments. The results showed that the viability, proliferation, and extracellular matrix (ECM) secretion of MSCs had no significant difference on scaffolds with diverse stiffness but the degree of collagen deposition of MSCs gradually increased with the increase of scaffold stiffness both under normoxia and hypoxia. Compared to normoxia, the viability, proliferation, ECM secretion, vascular endothelial growth factor (VEGF) expression, and osteogenis of MSCs on the scaffolds with the same stiffness were evidently inhibited by hypoxia. Additionally, under hypoxic condition, the expression of VEGF and hypoxia inducible factor 1α(HIF-1α) in MSCs on the low stiffness scaffold was markedly increased comparing to those on other groups. In summary, we found that the low stiffness scaffold can improved the proliferation and osteoginic differentiation of MSCs under hypoxic environment, which may help to explore efficient methods for bone defect repairing.

关键词： Mesenchymal stem cells Hypoxia Matrix stiffness Demineralized bone scaffold Osteogenic differentiation

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咏史怀古类古诗词教学价值分析及对策研究

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科教文汇 2025年第1期 164-167页

作者：刘徽刘媛媛衡阳师范学院文学院湖南衡阳421010

咏史怀古类古诗词对学生的知识、审美、情感等方面具有重要价值。针对当前咏史怀古类古诗词存在的一些问题,教师可以从创设情境、优化诵读、群文阅读等角度,探索咏史怀古类古诗词的教学对策。

关键词：咏史怀古类古诗词教学价值教学对策

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Protonated and layered transition metal oxides as solid acids for dehydration of biomass-based fructose into 5-hydroxymethylfurfural

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Journal of Energy Chemistry 2017年第1期26卷 147-154页

作者： Jiawei Zhong yuanyuan Guo Jinzhu Chen Key Laboratory of Renewable Energy Guangdong Key Laboratory of New and Renewable Energy Research and Development Guangzhou Institute of Energy Conversion Chinese Academy of Sciences University of Chinese Academy of Sciences

A serial of protonated and layered transition metal oxides, including layered HTaWO6, HNbMoO6 as well as HNbWO6, were synthesized by solid-state reaction and ion-exchange. The layered HTaWO6 has been systematically studied as a solid acid to realize the dehydration of fructose to 5-hydroxymethylfurfural (HMF). The transition metal oxide samples were characterized with ICP-OES, EDS, XRD, XPS, SEM, TGA, FT-IR, N-2 adsorption-desorption and NH3-TPD. The influential factors such as reaction temperature, reaction time, solvent, catalyst amount and substrate concentration were deeply investigated. The optimized fructose conversion rate of 99% with HMF yield of 67% were achieved after 30 min at 140 degrees C in dimethylsulfoxide. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

关键词： Biomass Dehydration 5-HYdroxymethylfurfural Layered transition metal oxide Solid acid

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Impacts of hydraulic redistribution on eco-hydrological cycles： A case study over the Amazon basin

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Science China Earth Sciences 2018年第9期61卷 1330-1340页

作者： yuanyuan WANG Binghao JIA Zhenghui XIE Beijing Meteorological Observatory Beijing 100089 China State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

Hydraulic redistribution(HR)refers to the process of soil water transport through the low-resistance pathway provided by plant *** has been observed in field studies and proposed to be one of the processes that enable plants to resist water ***,most land-surface models(LSMs)currently do not include this underground root *** this study,a HR scheme was incorporated into the Community Land Model version 4.5(CLM4.5)to investigate the effect of HR on the eco-hydrological *** paired numerical simulations(with and without the new HR scheme)were conducted for the Tapajos National Forest km83(BRSa3)site and the *** for the BRSa3 site in the Amazon showed that HR during the wet season was small,<0.1 mm day^(–1),transferring water from shallow wet layers to deep dry layers at night;however,HR in the dry season was more obvious,up to 0.3 mm day^(–1),transferring water from deep wet layers to shallow dry layers at *** incorporating HR into CLM4.5,the new model increased gross primary production(GPP)and evapotranspiration(ET)by 10%and 15%,respectively,at the BRSa3 site,partly overcoming the *** the Amazon,regional analysis also revealed that vegetation responses(including GPP and ET)to seasonal drought and the severe drought of 2005 were better captured with the HR scheme incorporated.

关键词： Land-surface model CLM4.5 Hydraulic redistribution Gross primary production Evapotranspiration

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Effect of carbon black on the dynamic moduli of asphalt mixtures and its master curves

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Frontiers of Structural and Civil Engineering 2019年第4期13卷 918-925页

作者： Chuangmin LI Fanbo NING yuanyuan LI Engineering Laboratory of Spatial Information Technology of Highway Geological Disaster Early Warning in Hunan Province Changsha University of Science & Technology Changsha 410114 China School of Traffic and Transportation Engineering Changsha University of Science &Technology Changsha 410114 China State Key Laboratory of Silicate Materials for Architectures Wuhan University of Technology Wuhan 430070 China

Modulus is one of the main parameters during the design of asphalt pavement structure, the newest specifications of China gives the dynamic moduli ranges of commonly used asphalt mixtures with base asphalt (BA) or styrene-butadiene-styrene modified asphalt (SBS MA), while the moduli ranges of mixtures with carbon black modified asphalt (CB MA) are not recommended. To investigate the CB effect on the dynamic moduli of CB MA mixtures, one commonly used asphalt mixture (AC-20) was designed with BA, SBS MA, and CB MA, respectively. Then, the uniaxial compression dynamic modulus tests were conducted at different temperatures and loading frequencies, the master curves of asphalt mixtures were analyzed based on the time-temperature equivalence principle. The results show that with increasing loading frequency, the temperature dependence of dynamic moduli of all asphalt mixtures tend to be less obvious. Both SBS and CB can decrease the temperature sensitivity of asphalt mixture, the SBS MA mixture has the lowest temperature sensitivity, followed by CB MA and BA mixture. In addition, CB and SBS can obviously improve the dynamic modulus of the BA mixture, enhance the anti-deformation performance of pavement structure, and the improvement effect of CB is almost the same with SBS.

关键词： dynamic modulus carbon black master curve modified asphalt asphalt mixture

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Analysis of Incomplete Data of Accelerated Life Testing with Competing Failure Modes

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Chinese Journal of Mechanical Engineering 2009年第6期22卷 883-889页

作者： TAN yuanyuan ZHANG Chunhua CHEN Xun College of Mechatronics Engineering and Automation National University of Defense Technology Changsha 410073 China

Data obtained from accelerated life testing （ALT） when there are two or more failure modes, which is commonly referred to as competing failure modes, are often incomplete. The incompleteness is mainly due to censoring, as well as masking which might be the case that the failure time is observed, but its corresponding failure mode is not identified. Because the identification of the failure mode may be expensive, or very difficult to investigate due to lack of appropriate diagnostics. A method is proposed for analyzing incomplete data of constant stress ALT with competing failure modes. It is assumed that failure modes have s-independent latent lifetimes and the log lifetime of each failure mode can be written as a linear function of stress. The parameters of the model are estimated by using the expectation maximum （EM） algorithm with incomplete data. Simulation studies are performed to check＇model validity and investigate the properties of estimates. For further validation, the method is also illustrated by an example, which shows the process of analyze incomplete data from ALT of some insulation system. Because of considering the incompleteness of data in modeling and making use of the EM algorithm in estimating, the method becomes more flexible in ALT analysis.

关键词： accelerated life testing competing failure modes expectation maximum algorithm incomplete data Monte Carlo simulation

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Structure and flow calculation of cake layer on microfiltration membranes

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Journal of Environmental Sciences 2017年第6期29卷 95-101页

作者： Yadong Yu Zhen Yang yuanyuan Duan Key Laboratory for Thermal Science and Power Engineering of MOE Beijing Key Laboratory for CO2 Utilization and Reduction TechnologyTsinghua UniversityBeijing 100084China

Submerged membrane bioreactors （SMBR） are widely used in wastewater treatment. The permeability of a membrane declines rapidly because of the formation of a cake layer on the membrane surface. In this paper, a multiple staining protocol was conducted to probe the four major foulants in the cake layer formed on a filtration membrane. Fluorescent images of the foulants were obtained using a confocal laser scanning microscope （CLSM）. The three dimensional structure of the cake layer was reconstructed, and the internal flow was calculated using computational fluid dynamics （CFD）. Simulation results agreed well with the experimental data on the permeability of the cake layer during filtration and showed better accuracy than the calculation by Kozeny-Carman method. B-D-Glucopyranose polysaccharides and proteins are the two main foulants with relatively large volume fractions, while a-D-glucopyranose polysaccharides and nucleic acids have relatively large specific surface areas. The fast growth of B-D-glucopyranose polysaccharides in the volume fraction is mainly responsible for the increase in cake volume fraction and the decrease in permeability. The specific area, or the aggregation/dispersion of foulants, is less important to its permeability compared to its volume fraction.

关键词： Membrane fouling CLSM Cake layer CFD Permeability

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重庆市中心城区儿童友好城市规划路径研究

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城市建筑 2025年第1期22卷 88-92页

作者：李圆圆王波西南大学园艺园林学院重庆市北碚区妇女联合会

在全国推行儿童友好城市和社区创建的背景下,重庆市积极探索具有地域特色的儿童友好城市规划。文章结合国内外儿童友好城市和社区的研究基础和建设经验,以社区规划师和高校研究者的双重身份介入,从服务空间、活动空间、出行空间三个方面... 详细信息

在全国推行儿童友好城市和社区创建的背景下,重庆市积极探索具有地域特色的儿童友好城市规划。文章结合国内外儿童友好城市和社区的研究基础和建设经验,以社区规划师和高校研究者的双重身份介入,从服务空间、活动空间、出行空间三个方面,针对重庆市中心城区提出儿童友好城市和社区的规划指引,并依托三级规划指引要求,为科学有序推进儿童友好相关工作提供参考路径。

关键词：儿童友好城市和社区规划指引重庆市中心城区实践路径

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Pharmacological strategies for treating misfolded rhodopsinassociated autosomal dominant retinitis pigmentosa

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Neural Regeneration Research 2022年第1期17卷 110-112页

作者： Yibo Xi yuanyuan Chen Department of Ophthalmology University of PittsburghPittsburghPAUSA Department of Pharmacology and Chemical Biology University of PittsburghPittsburghPAUSA McGowan Institute of Regenerative Medicine University of PittsburghPittsburghPAUSA

Mutations that cause protein misfolding are implicated in conditions such as retinitis pigmentosa(RP),Usher Syndrome,and myocilin associated primary open angle *** aggregation and continuous degradation of a highly abundant misfolded protein add proteolytic load of the affected *** subtle balance of cellular homeostasis,once disrupted by an overwhelmed proteolytic system,will lead to cell death and tissue degeneration.

关键词： retinitis degeneration homeostasis

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Distribution of Helicobacter pylori in north China

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World Journal of Gastroenterology 2005年第23期11卷 3523-3527页

作者： Yue-HuaGong YingWang yuanyuan CancerInstituteoftheFirstAffiliatedHospitalofChinaMedicalUniversityShenyang110001 LiaoningProvinceChina

AIM: To compare the distribution of virulence-associatedgenotypes of Helicobacter pylori(H pylori) in two areas of north China with different gastric cancer risk and furthermore probe into the pathogenicity of the bacterium. METHODS: Gastric biopsies were taken from 355 subjects from Zhuanghe, a high risk area of gastric cancer, and 136 subjects from Shenyang, a low risk area of gastric cancer. A total of 149 H pylori strains isolated from these patients were studied by PCR for differences in the genotypes of cagA, vac A, and ***: In patients with high risk for gastric cancer, higher frequencies of vacA s1 or s1m1b genotypes were found as compared to those from the low risk area. CONCLUSION: There is significantly different distribution of H pylori genotypes between Zhuanghe and Shenyang areas in north China.

关键词： Helicobacter pylori Gastric disease cagA vacA iceA Virulence genotype High-risk area

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