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Topological Catenation Enhances Elastic Modulus of Single Linear Polycatenane

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Chinese Journal of Polymer Science 2023年第9期41卷 1486-1496,I0009页

作者： Yao-xing Chen xi-qin cai Guo-Jie Zhang Department of Chemical Engineering School of Chemistry and Chemical EngineeringGuangzhou UniversityGuangzhou510006China

Entropic elasticity of single chains underlies many fundamental aspects of mechanical properties of polymers,such as high elasticity of polymer networks and viscoelasticity of polymer liquids.On the other hand,single chain elasticity is further rooted in chain connectivity.Recently,mechanically interlocked polymers,including polycatenanes and polyrotaxanes,which are formed by connecting their building blocks(cyclic and linear chains)through topological bonds(e.g.,entanglements),emerge as a conceptually new kind of polymers.In this work,we employ computer simulations to study linear elasticity of single linear polycatenane(or[n]catenane),in which n rings are interlocked through catenation into a chain of linear architecture.Aim of this work is to illuminate the specific role of catenation topology in the elastic moduli of linear polycatenanes by comparing with those of their[n]bonded-ring counterparts,which are formed by connecting the same number of rings but via covalent bonds.Simulation results lead to a conclusion that topological catenation makes[n]catenanes exhibit larger elastic moduli than their linear and[n]bonded-ring counterparts,i.e.,larger elastic moduli in the case of[n]catenanes.Furthermore,it is revealed that those[n]catenanes composed of a smaller number of rings(smaller n)possesses larger elastic moduli than others of the same total chain lengths.Molecular mechanisms of these findings are discussed based on conformational entropy due to topological constraints.

关键词： Single chain elasticity Polycatenane Computer simulation

Graphitic carbon nitride nanosheets mitigate cadmium toxicity in Glycine max L.by promoting cadmium retention in root and improving photosynthetic performance

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Journal of Environmental Sciences 2024年第5期139卷 543-555页

作者： Kai Xu Yunyu Guo Chenghua xing Ronglong Fu Bin Zou Rongchuan Liu Luyi cai Jianfang Yan xi-Lin Wu Miaozhen cai College of Geography and Environmental Sciences Zhejiang Normal UniversityJinhua 321004China College of Agriculture Jinhua PolytechnicJinhua 321007China

Cadmium(Cd)pollution poses a serious threat to plant growth and yield.Nanomaterials have shown great application potential for alleviation of Cd toxicity to plants.In this study,we applied graphitic carbon nitride nanosheets(g-C_(3)N_(4)NSs)for alleviation of Cd-toxicity to soybean(Glycine max L.).The g-C_(3)N_(4)NSs supplementation significantly improved plant growth and reduced oxidative damage in the Cd-toxicated soybean seedlings through hydroponic culture.Particularly,the g-C_(3)N_(4)NSs dynamically regulated the root cell wall(RCW)components by increasing pectin content and modifying its demethylation via enhancing pectin methylesterase(PME)activity,therefore greatly enhanced stronger RCW-Cd retention(up to 82.8%)and reduced Cd migration to the shoot.Additionally,the g-C_(3)N_(4)NSs reversed the Cd-induced chlorosis,increased photosynthetic efficiency because of enhancement in F_v/F_mration,Y(Ⅱ)and sugars content.These results provide new insights into the alleviation of Cd toxicity to plants by g-C_(3)N_(4)NSs,and shed light on the application of low-cost and environmental-friendly carbon-based NMs for alleviating heavy metal toxicity to plants.

关键词： Cadmium Carbon nitride nanosheets Cell wall Pectin Pectin methylesterase Soybean

Chain Extender-induced Hydrogen Bonding Organization Determines the Morphology and Properties of Thermoplastic Polycarbonate Polyurethane

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Chinese Journal of Polymer Science 2024年第1期42卷 87-96,I0009页

作者： Yi-Lang qin Ping Zhu Chen-xi Ouyang xia Dong Fuwai Hospital Chinese Academyof Medical Sciences&Peking Union Medical College/National Center for Cardiovascular DiseasesBejing 100037China CASKey Laboratoryof Engineering Plastics CAS Research/Education Centerfor Excellence in Molecular SciencesInstitute ofChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Thermoplastic polycarbonate polyurethanes(PCUs) are multiblock copolymers that have been applied for medical devices for long time. Aliphatic diols are common chain extenders(CE) involved in the composition of the hard segments of PCU. However, limited knowledge was discovered about how the chemical structure of CE affects the hydrogen bonding organization within PCUs and their mechanical properties.To investigate this problem, a group of PCUs were synthesized respectively by extending the polymer chain with 1,4-butanediol(BDO),aminoethanol(MEA), ethanediol(EO) as three kinds of chain extenders. Tiny differences in the CE chemical structure results in remarkable variations in phase separation, condensed morphologies, thermal and mechanical properties, which are characterized by Fourier transform infrared spectrometer, atomic force microscopy, small-angle X-ray scattering, differential scanning calorimetry, and tensile tests. The microstructural evolution during unilateral deformation and the different mechanism induced by the different CEs was probed and unveil by in situ wide-and small-angle X-ray diffraction. Symmetry of CE can improve the organization of the hydrogen bonding. The coherence strength of the urethane/urea group also plays a key role by comparing the two PCUs with ethanediol and aminoethanol.

关键词： Thermoplastic polycarbonate polyurethane Chain extender Hydrogen bonding Mechanical properties

Roughness characterization and shearing dislocation failure for rock-backfill interface

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1167-1176页

作者： Meifeng cai Zhilou Feng Qifeng Guo xiong Yin Minghui Ma Xun xi Key Laboratory of High-Efficient Mine and Safety of Metal Mines of Ministry of Education Beijing 100083China Key Laboratory of Urban and Underground Space Engineering University of Science and Technology BeijingBeijing 100083China Shandong Gold Group Co LtdJinan 250102China

Shearing dislocation is a common failure type for rock–backfill interfaces because of backfill sedimentation and rock strata movement in backfill mining goaf.This paper designed a test method for rock–backfill shearing dislocation.Using digital image techno-logy and three-dimensional(3D)laser morphology scanning techniques,a set of 3D models with rough joint surfaces was established.Further,the mechanical behavior of rock–backfill shearing dislocation was investigated using a direct shear test.The effects of interface roughness on the shear–displacement curve and failure characteristics of rock–backfill specimens were considered.The 3D fractal dimen-sion,profile line joint roughness coefficient(JRC),profile line two-dimensional fractal dimension,and the surface curvature of the frac-tures were obtained.The correlation characterization of surface roughness was then analyzed,and the shear strength could be measured and calculated using JRC.The results showed the following:there were three failure threshold value points in rock–backfill shearing dis-location:30%–50%displacement before the peak,70%–90%displacement before the peak,and 100%displacement before the peak to post-peak,which could be a sign for rock–backfill shearing dislocation failure.The surface JRC could be used to judge the rock–backfill shearing dislocation failure,including post-peak sliding,uniform variations,and gradient change,corresponding to rock–backfill disloca-tion failure on the field site.The research reveals the damage mechanism for rock–backfill complexes based on the free joint surface,fills the gap of existing shearing theoretical systems for isomerism complexes,and provides a theoretical basis for the prevention and control of possible disasters in backfill mining.

关键词： rock–backfill roughness correlation characterization shearing dislocation interface failure

Sedimentary Environment and Mineralization of the Black Shale Polymetallic Layer in the Early Cambrian,SW China:Constraints from in situ LA-ICP-MS Analysis of Pyrite

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Acta Geologica Sinica(English Edition) 2024年第2期98卷 416-429页

作者： YANG Zhen FU Yong LI Chao cai xi GUO Chuan College of Eco-Environmental Engineering Guizhou Minzu UniversityGuiyang 550025China College of Resources and Environmental Engineering Guizhou UniversityGuiyang 550025China Key Laboratory of Karst Georesources and the Environment Ministry of EducationGuizhou UniversityGuiyang 500025China National Research Center for Geoanalysis Chinese Academy of Geological SciencesBeijing 100037China

A polymetallic layer is usually developed at the bottom of the early Cambrian black shale in Guizhou Province.The mineral that makes up the polymetallic layer is related to the sedimentary facies.To analyze the differentiation mechanism between polymetallic deposits(Ni-Mo and V),the Zhijin Gezhongwu profile located in the outer shelf and the Sansui Haishan V deposit located in the lower slope are selected to study the in situ sulfur isotopes and trace elements of pyrite.The results show that δ^(34)S values of pyrite vary widely from−7.8‰to 28‰in the Gezhongwu profile,while the δ^(34)S values are relatively uniform(from 27.8‰to 38.4‰)in the Haishan profile.The isotopic S composition is consistent with the transition that occurs in the sedimentary phase from the shelf to the deep sea on the transgressive Yangtze platform;this indicates that the δ^(34)SO_(4)^(2−)values in seawater must be differently distributed in depositional environments.The sulfur in the Ni-Mo layer is produced after the mixing of seawater and hydrothermal fluid,while the V layer mainly originates from seawater.Overall,the Ni-Mo and V deposits have been differentiated primarily on the basis of the combined effect of continental weathering and hydrothermal fluid.

关键词： sedimentary environment black shale polymetallic layer pyrite early Cambrian

Low-energy-consumption temperature swing system for CO_(2) capture by combining passive radiative cooling and solar heating

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Green Energy & Environment 2024年第3期9卷 507-515页

作者： Ying-xi Dang Peng Tan Bin Hu Chen Gu xiao-qin Liu Lin-Bing Sun State Key Laboratory of Materials-Oriented Chemical Engineering Jiangsu National Synergetic Innovation Center for Advanced Materials(SICAM)College of Chemical EngineeringNanjing Tech UniversityNanjing211816China

Temperature-swing adsorption(TSA)is an effective technique for CO_(2) capture,but the temperature swing procedure is energy-intensive.Herein,we report a low-energy-consumption system by combining passive radiative cooling and solar heating for the uptake of CO_(2) on commercial activated carbons(CACs).During adsorption,the adsorbents are coated with a layer of hierarchically porous poly(vinylidene fluoride-co-hexafluoropropene)[P(VdF-HFP)HP],which cools the adsorbents to a low temperature under sunlight through radiative cooling.For desorption,CACs with broad absorption of the solar spectrum are exposed to light irradiation for heating.The heating and cooling processes are completely driven by solar energy.Adsorption tests under mimicked sunlight using the CACs show that the performance of this system is comparable to that of the traditional ones.Furthermore,under real sunlight irradiation,the adsorption capacity of the CACs can be well maintained after multiple cycles.The present work may inspire the development of new temperature swing procedures with little energy consumption.

关键词： CO_(2)capture Solar heating Passive radiative cooling Temperature swing adsorption

Modeling of multiphase flow in low permeability porous media:Effect of wettability and pore structure properties

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第4期16卷 1127-1139页

作者： xiangjie qin Yuxuan xia Juncheng Qiao Jiaheng Chen Jianhui Zeng Jianchao cai National Key Laboratory of Petroleum Resources and Engineering China University of PetroleumBeijing102249China Research Institute of Petroleum Exploration and Development Beijing10083China

Multiphase flow in low permeability porous media is involved in numerous energy and environmental applications.However,a complete description of this process is challenging due to the limited modeling scale and the effects of complex pore structures and wettability.To address this issue,based on the digital rock of low permeability sandstone,a direct numerical simulation is performed considering the interphase drag and boundary slip to clarify the microscopic water-oil displacement process.In addition,a dual-porosity pore network model(PNM)is constructed to obtain the water-oil relative permeability of the sample.The displacement efficiency as a recovery process is assessed under different wetting and pore structure properties.Results show that microscopic displacement mechanisms explain the corresponding macroscopic relative permeability.The injected water breaks through the outlet earlier with a large mass flow,while thick oil films exist in rough hydrophobic surfaces and poorly connected pores.The variation of water-oil relative permeability is significant,and residual oil saturation is high in the oil-wet system.The flooding is extensive,and the residual oil is trapped in complex pore networks for hydrophilic pore surfaces;thus,water relative permeability is lower in the water-wet system.While the displacement efficiency is the worst in mixed-wetting systems for poor water connectivity.Microporosity negatively correlates with invading oil volume fraction due to strong capillary resistance,and a large microporosity corresponds to low residual oil saturation.This work provides insights into the water-oil flow from different modeling perspectives and helps to optimize the development plan for enhanced recovery.

关键词： Low permeability porous media Water-oil flow Wettability Pore structures Dual porosity pore network model(PNM) Free surface model

Irisin-loaded electrospun core-shell nanofibers as calvarial periosteum accelerate vascularized bone regeneration by activating the mitochondrial SIRT3 pathway

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Regenerative Biomaterials 2024年第1期3卷 44-57页

作者： xi Hua Mingzhuang Hou Lei Deng Nanning Lv Yong Xu Xuesong Zhu Huilin Yang qin Shi Hao Liu Fan He Department of Orthopaedics The First Affiliated Hospital of Soochow UniversitySoochow UniversitySuzhou 215006China Orthopaedic Institute Suzhou Medical CollegeSoochow UniversitySuzhou 215000China Department of Orthopedics Suzhou Wuzhong People’s HospitalSuzhouJiangsu Province 215128China Department of Orthopedic Surgery Lianyungang Clinical College of Xuzhou Medical UniversityLianyungang 222003China

The scarcity of native periosteum poses a significant clinical barrier in the repair of critical-sized bone defects.The challenge of enhancing regenerative potential in bone healing is further compounded by oxidative stress at the fracture site.However,the introduction of artificial periosteum has demonstrated its ability to promote bone regeneration through the provision of appropriate mechanical support and controlled release of proosteogenic factors.In this study,a poly(L-lactic acid)(PLLA)/hyaluronic acid(HA)-based nanofibrous membrane was fabricated using the coaxial electrospinning technique.The incorporation of irisin into the core-shell structure of PLLA/HA nanofibers(PLLA/HA@Irisin)achieved its sustained release.In vitro experiments demonstrated that the PLLA/HA@Irisin membranes exhibited favorable biocompatibility.The osteogenic differentiation of bone marrow mesenchymal stem cells(BMMSCs)was improved by PLLA/HA@Irisin,as evidenced by a significant increase in alkaline phosphatase activity and matrix mineralization.Mechanistically,PLLA/HA@Irisin significantly enhanced the mitochondrial function of BMMSCs via the activation of the sirtuin 3 antioxidant pathway.To assess the therapeutic effectiveness,PLLA/HA@Irisin membranes were implanted in situ into critical-sized calvarial defects in rats.The results at 4 and 8 weeks post-surgery indicated that the implantation of PLLA/HA@Irisin exhibited superior efficacy in promoting vascularized bone formation,as demonstrated by the enhancement of bone matrix synthesis and the development of new blood vessels.The results of our study indicate that the electrospun PLLA/HA@Irisin nanofibers possess characteristics of a biomimetic periosteum,showing potential for effectively treating critical-sized bone defects by improving the mitochondrial function and maintaining redox homeostasis of BMMSCs.

关键词： periosteum irisin mitochondrial function critical-sized bone defect redox homeostasis

Oscillation properties of eigenfunctions for Sturm-Liouville problems with interface conditions via Prufer transformation

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Applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 191-200页

作者： LI Zhi-yu LI Kun cai Jin-ming qin Jian-fang ZHENG Zhao-wen School of Mathematical Sciences Qufu Normal UniversityQufu 273165China College of Mathematics and Systems Science Guangdong Polytechnic Normal UniversityGuangzhou 510665China

A class of Sturm-Liouville problems with discontinuity is studied in this paper.The oscillation properties of eigenfunctions for Sturm-Liouville problems with interface conditions are obtained.The main method used in this paper is based on Prufer transformation,which is different from the classical ones.Moreover,we give two examples to verify our main results.

关键词： Sturm-Liouville problem interface condition oscillatory solution