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Tailoring microstructure and electrical transportation through tensile stress in Bi_(2)Te_(3) thermoelectric fibers

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Journal of Materiomics 2020年第3期6卷 467-475页

作者： Min Sun Guowu Tang Bowen Huang Zhongjia Chen Yu-Jun Zhao Hanfu Wang Ziwen Zhao Dongdan Chen Qi Qian Zhongmin Yang School of Physics and Optoelectronics South China University of TechnologyGuangzhou510640China State Key Laboratory of Luminescent Materials and Devices Institute of Optical Communication MaterialsGuangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and DevicesGuangdong Provincial Key Laboratory of Fiber Laser Material and Applied TechniquesSouth China University of TechnologyGuangzhou510640China CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology of ChinaBeijing100190China Key Laboratory of Specialty Fiber Optics and Optical Access Networks Shanghai Institute for Advanced Communication and Data ScienceSchool of Communication and Information EngineeringShanghai UniversityShanghai200072China

Bismuth telluride(Bi_(2)Te_(3))has attracted much attention in the field of thermoelectrics since it is one kind of commercial room-temperature thermoelectric material.Herein three kinds of Bi_(2)Te_(3) thermoelectric fibers with internal tensile stress are fabricated utilizing an optical fiber template method.The effects of internal stress on the microstructure and the electrical transportation of Bi_(2)Te_(3) thermoelectric fibers are investigated.The Bi_(2)Te_(3) cores in the fibers are highly crystalline and possess a tensile nanosheet structure with preferential orientation as evidenced by X-ray diffraction and Raman studies.tensile stress can enhance electrical properties of the fibers.And a paper cup generator covered with 20 pieces of optimized fibers provides a μW-level output power.It is inferred that tensile stress tuning can be an effective tool for the material optimization of thermoelectric performance.

关键词： Bi_(2)Te_(3) Thermoelectric fiber tensile stress Electrical transportation

High-temperature oxidation behavior of DZ125 Ni-based superalloy under tensile stress

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Rare Metals 2022年第12期41卷 4188-4193页

作者： Hong-Yu Qi Xiao-Bo Liang Shao-Lin Li Xiao-Guang Yang School of Energy and Power Engineering Beihang UniversityBeijing 100191China Collaborative Innovation Center of Advanced Aero-Engine Beijing 100191China

The key in antioxidant capacity of aero-engine hot components is the protective oxide scales.Many factors can affect the performance of oxide scales.The effect of tensile stress on high-temperature oxidation behavior of directionally solidified DZ125 Ni-based superalloy was investigated by thermogravimetric analysis(TGA).tensile samples were subjected to stress of 100 MPa,and the oxidation behavior was studied at 980℃in air.The surface and cross-sectional morphologies of the oxidized coating were analyzed by scanning electron microscope(SEM).The influence of tensile stress on the oxidation behavior of directionally solidified DZ125 Ni-based superalloy at high temperature was discussed.Results show that an applied tensile stress generally leads to larger Cr/Ni mass ratio in the oxide scales,greater overall chromium depletion values directly under the oxide scales,lower specific weight gain values and thinner oxide scales.These factors are attributed to the formation of fast diffusion paths for Cr atoms to diffuse to the surface under tensile stress,thus causing a reduction in the duration of the less protective transient oxidation period and promoting a faster formation of the protective Cr_(2)O_(3)layer.

关键词： DZ125 Ni-based superalloy High-temperature oxidation tensile stress Diffusion

Xyloglucan for Generating tensile stress to Bend Tree Stem

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Molecular Plant 2009年第5期2卷 893-903页

作者： Kei'ichi Baba Yong Woo Park Tomomi Kaku Rumi Kaida Miyuki Takeuchi Masato Yoshida Yoshihiro Hosoo Yasuhisa Ojio Takashi Okuyama Toru Taniguchi Yasunori Ohmiya Teiji Kondo Ziv Shani Oded Shoseyov Tatsuya Awano Satoshi Serada Naoko Norioka Shigemi Norioka Takahisa Hayashi Kyoto University RISH Gokasho Uji Kyoto 611-0011 Japan Graduate School of Bioagricultural-Sciences Nagoya University Nagoya 464-8601 Japan Forest Tree Breeding Center Hitachi Ibaraki 319-1301 Japan CBD Technologies Rehovot 76100 Israel Division of Forest and Biomaterials Science Kyoto University Kyoto 606-8502 Japan Graduate School of Frontier Biosciences Osaka University Suita Osaka 565-0871 Japan Institute of Sustainability Science Kyoto University Gokasho Uji Kyoto 611-0011 Japan

In response to environmental variation, angiosperm trees bend their stems by forming tension wood, which consists of a cellulose-rich G （gelatinous）-Iayer in the walls of fiber cells and generates abnormal tensile stress in the secondary xylem. We produced transgenic poplar plants overexpressing several endoglycanases to reduce each specific polysaccharide in the cell wall, as the secondary xylem consists of primary and secondary wall layers. When placed horizontally, the basal regions of stems of transgenic poplars overexpressing xyloglucanase alone could not bend upward due to low strain in the tension side of the xylem. In the wild-type plants, xyloglucan was found in the inner surface of G-layers during multiple layering. In situ xyloglucan endotransglucosylase （XET） activity showed that the incorporation of whole xyloglucan, potentially for wall tightening, began at the inner surface layers S1 and S2 and was retained throughout G-layer development, while the incorporation of xyloglucan heptasaccharide （XXXG） for wall loosening occurred in the primary wall of the expanding zone. We propose that the xyloglucan network is reinforced by XET to form a further connection between wall-bound and secreted xyloglucans in order to withstand the tensile stress created within the cellulose G-layer micro fibrils.

关键词： G-layer tensile stress xyloglucan xyloglucan endotransglucosylase

Osteogenic differentiation of human adipose-derived mesenchymal stem cells under tensile stress regulated by Let-7i through the Wnt/β-catenin pathway by targeting Wnt10b

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Osteogenic differentiation of human adipose-derived mesenchy...

The Kinetics of Reorientation of Multi-Variants under the Continuous tensile stress: Phase-Field Simulation

第十四次中国口腔颌面外科学术会议

作者： Hongming Du Yadong Luo Haiyang Song Meng Li Heming Wu Oral and Maxillofacial Surgery Stomatological College of Nanjing Medical University General Department Stomatological College of Nanjing Medical University

Objective:Bone tissue engineering provides new methods to repair bone defects in oral and maxillofacial region, and human adipose-derived stem cells(hASCs) as seed cells is the key point. tensile stress can promote the osteogenic differentiation of hASCs in vitro. Methods:Microarray analysis data showed that Let-7 i was markedly downregulated in h ASCs under tensile stress treatment. Bioinformatic analysis and luciferase reporter assays revealed that Wnt10 b was a direct target of Let-7 i. Results:Under tensile stress, mimics-mediated gain-function studies revealed that forced expression of Let-7 i inhibited osteogenic differentiation of hASCs, whereas inhibition of Let-7 i by inhibitor obviously promoted osteogenic differentiation. Furthermore, Let-7 i overexpression decreased activity of the Wnt/β-catenin pathway, as indicated by lower expression of Wnt10 b, active β-catenin in Let-7 i-treated hASCs. By contrast, Let-7 i inhibition activated the Wnt/β-catenin pathway. Conclusion:Taken together, these results demonstrate that, under tensile stress, Let-7 i negatively regulates hASCs osteogenic differentiation through the Wnt/β-catenin pathway by directly targeting Wnt10 b.

关键词： hASCs osteogenic differentiation tensile stress Wnt/β-catenin Let-7i Wnt10b

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The Kinetics of Reorientation of Multi-Variants under the Co...

Numerical Simulation of stress Field in Physical Tempering Process of Flat Soda Lime Silica Glass

中国材料大会2012

作者： J.F. Wan J.H. Zhang Y.H. Rong School of Materials Science and Engineering Shanghai Jiao Tong University

ISBN: (纸本)9783037856093

The kinetics of martensitic variant reorientation as well as the evolutional pathway under the continuous tensile stress in NiMnGa alloys has been investigated by using Phase-field method. The simulated results revealed that the final structures and the pathway of evolutioncan be determined by the different external stress and there existed a critical stress to obtain the single variant. The related kinetics and the mechanism of the structural conversion were proposed to explain the inner physical nature. The pseudo-elasticity related to the structural conversion was also investigated. The mechanism of the motion for interfacial step associated with the nucleation and growth of one variant in another variant at the twin boundary was discussed.

关键词： Kinetics Reorientation Variant tensile stress Phase-field simulation.

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Journal of Wuhan University of Technology(Materials Science) 2023年第1期38卷 20-30页

作者：刘超英 HE Dongsheng OU Yingchun HE Feng HAO Lizi XU Shaokun MA Juanrong China Building Materials Academy Beijing 100024China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China China Helicopter Research and Development Institute Jingdezhen 333001China

Based on the analysis of different theory for glass tempering process,the“structural theory”with stress relaxation and structural relaxation effects was selected to investigate the tempering of flat glass quantificationally.The geometrical model with small size and non-homogeneous mesh were considered to build the finite element models according to the characteristics of stress field.The tempering process of flat glass with12 mm thickness was calculated with the verified finite element model.The transient and permanent stress of the central area,edge and corner end of the flat glass are obtained and analyzed.From the calculation results of basic case,the transient tensile stress at the upper surface of the central area,the center point of edge,the edge of edge,the edge of corner were 14.30,18.94,40.76 and 34.75 MPa,respectively.The transient tensile stress at these points were dangerous to promote the glass to break during the tempering.In addition,the point at the diagonal line of symmetry plane in the thickness direction,which is 14 mm from corner,has the maximum permanent tensile stress about 70.01 MPa in the flat glass after tempering.Thus,it is indicated that the corner is the weakest region in the tempered glass.

关键词： nite element tempering stress relaxation structural relaxation compressive stress tensile stress

Analysis of stresses at the center of transversely isotropic Brazilian disk

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第3期15卷 618-629页

作者： Ali Aminzadeh Florian Amann Institute of Geology of the Czech Academy of Sciences PragueCzech Republic Chair of Engineering Geology RWTH Aachen UniversityAachenGermany

This article presents the stresses at the center of a Brazilian disk(BD)for transversely isotropic rocks.It is shown that the solution of stresses at the center of an anisotropic disk is a function of the disk radius and the magnitude of applied load,as well as the material orientation with respect to the load axis and two dimensionless ratios with specific physical meanings and limitations.These two dimensionless parameters are the ratios of Young’s modulus and apparent shear modulus,although the ratio of apparent shear modulus will be eliminated if the Saint-Venant assumption is considered.Considerable finite element simulations are carried out to find the stresses at the disk center concerning the material orientation and the two dimensionless parameters.Also,an approximate formula obtained from analytical results,previously proposed in the literature for solving the tensile and compressive stresses at the disk center,is re-written and simplified based on these new definitions.The results of the approximate formula fitted to the analytical results are compared to those obtained from numerical solutions,suggesting a good agreement between the numerical and analytical methods.An approximate equation for the shear stress at the disk center is also formulated based on the numerical results.Finally,the influence of the assumptions for simplification of the proposed formula for the tensile,compressive,and shear stresses at the disk center is discussed,and simple and practical equations are proposed as estimations for the stresses at the center of the BD specimen for low to moderate anisotropic rocks.For highly anisotropic rocks,the reference plots can be used for more accuracy.

关键词： Brazilian test Transverse isotropy Rock anisotropy Anisotropic disk tensile stress Shear stress

Synergistic passivation of MAPbI_(3) perovskite solar cells by compositional engineering using acetamidinium bromide additives

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Journal of Energy Chemistry 2021年第8期30卷 755-762,I0016页

作者： Kyungeun Jung Weon-Sik Chae Jae Won Choi Ki Chul Kim Man-Jong Lee Department of Chemistry Konkuk University143-701 SeoulSouth Korea Department of Advanced Technology Fusion Konkuk University143-701 SeoulSouth Korea Analysis Research Division Daegu CenterKorea Basic Science Institute702-701 DaeguSouth Korea Division of Chemical Engineering Konkuk University05029 SeoulSouth Korea

For the global commercialization of highly efficient and stable perovskite solar cells(PSCs),it is necessary to effectively suppress the formation of various defects acting as nonradiative recombination sources in perovskite light-harvesting materials.Interfacial defects between the charge-selective layer and the perovskite are easily formed in the solution process used to fabricate perovskite films.In addition,owing to the difference in thermal expansion coefficients between the substrate and the perovskite film,internal residual tensile stress inevitably occurs,resulting in increased nonradiative recombination.Herein,a simple compositional engineering scheme for realizing efficient and stable PSCs,which incorporates acetamidinium bromide(AABr)as an additive into the MAPbI_(3) lattice,is proposed.As an additive,AABr has been found to provide synergistic multiple passivation for both internal and interfacial defects.AABr was found to effectively release the tensile strain of the MAPbI_(3) film by forming a structure stabilized by NH-I hydrogen bonds,as evidenced by calculations based on density functional theory(DFT).Furthermore,the incorporated AABr additives created a charge carrier recombination barrier to enhance charge collection capability by reducing interfacial defects.Accordingly,a power conversion efficiency(PCE)of 20.18%was achieved using a planar device employing AABr-incorporated MAPbI_(3).This was substantially higher than the 18.32% PCE of a pristine MAPbI_(3)-based device.Notably,unencapsulated PSCs using AABr-incorporated MAPbI_(3) absorbers exhibited excellent long-term stability,maintaining>95% of initial PCE up to 1200 hours in ambient air.

关键词： Acetamidinium bromide Planar perovskite solar cell tensile stress Interface passivation Recombination barrier

A hybrid simulation approach to evaluate stimulation micro-seismic events and production potential of fractured geothermal reservoirs

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Petroleum Research 2020年第2期5卷 131-143页

作者： Reda Abdel Azim Petroleum Engineering Department American University of Kurdistan Zakho Rd.99641DohoukIraq

This study presents an integrated approach to simulate fluid flow and to predict the micro seismic eventsduring stimulation and circulation of cold water over a longer term in geothermal reservoirs. The integrated approach based on new three dimensional fully coupled thermo-poroelastic numerical model forevaluation of energy recoverable. In the presented approach, the fracture aperture due to fractureslippage is calculated by shear and dilation. The shear slippage is controlled by the concept of shearfailure using linear Mohr-Coulomb criterion. The numerical model is validated against an analytical Oda’smodel for permeability tensor calculation and against an analytical solution for thermo-poroelasticmodel. The heat transfer between the rock and fluid is modelled by using the conductive heat transferwithin the reservoir rock and convective heat transfer in discrete fractures. The thermal stress changesare included in the model to be studied by using roughness induced shear displacement principle in aporo-thermo-elastic environment. The fracture aperture changes are estimated by using an analyticalmodel based on the distributed dislocation technique. The roughness of fracture surfaces is used in thecalculation of residual fracture aperture. The presented approach is used to study the potential ofpermeability enhancement for Habanero geothermal reservoir at a depth of 3600 m. The result show thatthe increasing in tensile effective stress tend to increase the fracture aperture within the zone of cooling.This increasing in fracture aperture led to significant changes in pressure distribution (decrease inimpedance) and hence, increase in the flow rate.

关键词： Fractured reservoirs Finite element Permeability tensor Fracture aperture tensile stress Fractal density and dimension