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Experimental Study on Flow Boiling Heat Transfer Characteristics of Microencapsulated Phase Change Material Suspension

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Journal of Thermal Science 2023年第4期32卷 1547-1557页

作者： TAN Zhenyu LI Xunfeng HUAI Xiulan chenG Keyong chen junlin Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China School of Engineering Science University of Chinese Academy of SciencesBeijing100049China Nanjing Institute of Future Energy System Nanjing211135China

Due to its core phase change characteristics,microencapsulated phase change material(MPCM)can make many base fluids have better heat transfer *** this paper,the flow boiling heat transfer characteristics of fluorinated liquid-based microencapsulated phase change material suspension(MPCMS)through vertical transparent quartz channel were *** effects of MPCM core phase change temperature and suspension flow velocity on boiling heat transfer coefficient and critical heat flux were discussed,*** results show that the appropriate concentration of MPCMS can enhance both the boiling heat transfer coefficient and the critical heat *** strengthening effect becomes weak with the increase of suspension flow *** maximum strengthening rates of critical heat flux appear at 0.05 m/s,which are 25%(MPCMS(70℃)),16%(MPCMS(58℃))and 10%(MPCMS(28℃)).The phase change temperature of the MPCM core has important effects on the boiling heat transfer coefficient and the critical heat *** results showed that the MPCM with core phase change temperature higher than the boiling temperature of base fluid has the best enhancement *** bubble behavior in vertical tube with different heat flux can be observed by high-speed photography *** particle core phase change in MPCMS inhibits the aggregation of bubbles and forms many small bubbles to enhance heat *** work lays a foundation for further exploring the industrial application of MPCMS.

关键词： flow boiling enhancement flow visualization suspension microencapsulated phase change material

Numerical study of collection efficiency and heat-transfer characteristics of packed granular filter

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Particuology 2019年第5期17卷 75-82页

作者： junlin chen Xunfeng Li Xiulan Huai Yongwei Wang Jingzhi Zhou Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China

The collection mechanism and heat-transfer characteristics of a packed granular filter were investigated using a three-dimensional randomly packed granular filter model. The bridging method was introduced to optimize the grids of contact points between granules. The influences of granular bed depth, gas velocity, and gas temperature on grade collection efficiency were investigated. The results indicated that a decrease of temperature improved collection efficiency when the particle diameter was greater than 5 |xm. The grade collection efficiency maintained a stable value when the Stokes number, St, was less than 0.009, but increased linearly with ig(St) when St > 0.009. A logarithmic mean temperature difference method was used to obtain overall heat-transfer coefficients of gas-solid two-phase flow through the packed granular filter. The results showed that convective heat transfer was enhanced due to the intro-duction of solid particles in the bed. The overall heat-transfer coefficient increased approximately linearly with an increase in particle loading ratio. The Nusselt number was related to the Reynolds number, the Archimedes number, and the particle loading ratio.

关键词： Packed granular filter Gas-solid two-phase flow Grade collection efficiency Heat transfer

Automatic identification of rock discontinuity and stability analysis of tunnel rock blocks using terrestrial laser scanning

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第7期15卷 1810-1825页

作者： Meng Wang Jiawen Zhou junlin chen Nan Jiang Puwen Zhang Haibo Li State Key Laboratory of Hydraulics and Mountain River Engineering Sichuan UniversityChengdu610065China College of Water Resource and Hydropower Sichuan UniversityChengdu610065China

Local geometric information and discontinuity features are key aspects of the analysis of the evolution and failure mechanisms of unstable rock blocks in rock *** study demonstrates the integration of terrestrial laser scanning(TLS)with distinct element method for rock mass characterization and stability analysis in *** records detailed geometric information of the surrounding rock mass by scanning and collecting the positions of millions of rock surface points without *** conducting a fuzzy K-means method,a discontinuity automatic identification algorithm was developed,and a method for obtaining the geometric parameters of discontinuities was *** method permits the user to visually identify each discontinuity and acquire its spatial distribution features(***,spac-ings,trace lengths)in great *** with hand mapping in conventional geotechnical surveys,the geometric information of discontinuities obtained by this approach is more accurate and the iden-tification is more ***,a discrete fracture network with the same statistical characteristics as the actual discontinuities was generated with the distinct element method,and a representative nu-merical model of the jointed surrounding rock mass was *** means of numerical simulation,potential unstable rock blocks were assessed,and failure mechanisms were *** method was applied to detection and assessment of unstable rock blocks in the spillway and sand flushing tunnel of the Hongshiyan hydropower project after a *** results show that the noncontact detection of blocks was more labor-saving with lower safety risks compared with manual surveys,and the stability assessment was more reliable since the numerical model built by this method was more consistent with the distribution characteristics of actual *** study can provide a reference for geological survey and unstable rock block hazard mitigation in tunnels subjected

关键词： Rock tunnel Terrestrial laser scanning(TLS) Discontinuity automatic identification Distinct element method Rock block stability assessment

A novel bioartificial pancreas fabricated via islets microencapsulation in anti-adhesive core-shell microgels and macroencapsulation in a hydrogel scaffold prevascularized in vivo

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Bioactive Materials 2023年第9期27卷 362-376页

作者： Haofei Li Yulian Shang Qi Feng Yang Liu junlin chen Hua Dong School of Materials Science and Engineering South China University of TechnologyGuangzhou510006China National Engineering Research Center for Tissue Restoration and Reconstruction(NERC-TRR) Guangzhou510006China Key Laboratory of Biomedical Materials and Engineering of the Ministry of Education South China University of TechnologyGuangzhou510006China School of Biomedical Science and Engineering South China University of TechnologyGuangzhou510006China Guangdong Province Key Laboratory of Biomedical Engineering South China University of TechnologyGuangzhou510641China

Islets transplantation is a promising treatment for type 1 diabetes mellitus. However, severe host immune rejection and poor oxygen/nutrients supply due to the lack of surrounding capillary network often lead to transplantation failure. Herein, a novel bioartificial pancreas is constructed via islets microencapsulation in core-shell microgels and macroencapsulation in a hydrogel scaffold prevascularized in vivo. Specifically, a hydrogel scaffold containing methacrylated gelatin (GelMA), methacrylated heparin (HepMA) and vascular endothelial growth factor (VEGF) is fabricated, which can delivery VEGF in a sustained style and thus induce subcutaneous angiogenesis. In addition, islets-laden core-shell microgels using methacrylated hyaluronic acid (HAMA) as microgel core and poly(ethylene glycol) diacrylate (PEGDA)/carboxybetaine methacrylate (CBMA) as shell layer are prepared, which provide a favorable microenvironment for islets and simultaneously the inhibition of host immune rejection via anti-adhesion of proteins and immunocytes. As a result of the synergistic effect between anti-adhesive core-shell microgels and prevascularized hydrogel scaffold, the bioartificial pancreas can reverse the blood glucose levels of diabetic mice from hyperglycemia to normoglycemia for at least 90 days. We believe this bioartificial pancreas and relevant fabrication method provide a new strategy to treat type 1 diabetes, and also has broad potential applications in other cell therapies.

关键词： Type 1 diabetes Bioartificial pancreas Islet encapsulation Core-shell microgel Prevascularized scaffold

Ultrasound responsive microcapsules for antibacterial nanodrug delivery

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Nano Research 2023年第2期16卷 2738-2748页

作者： Jilin Fan Mingjun Xuan Pengkun Zhao Mark Loznik junlin chen Fabian Kiessling Lifei Zheng Andreas Herrmann Wenzhou Institute University of Chinese Academy of SciencesWenzhou 325001China DWI—Leibniz Institute for Interactive Materials Forckenbeckstr.5052074 AachenGermany Institute of Technical and Macromolecular Chemistry RWTH Aachen UniversityWorringerweg 152074 AachenGermany Institute for Experimental Molecular Imaging University Hospital AachenForckenbeckstr.5552074 AachenGermany

The development of ultrasound-responsive microcapsule structures has resulted in several spatiotemporally controlled drug delivery systems for macromolecular cargoes,including proteins,nucleic acids,and even cells for biomedical ***,utilizing microcapsules to transport small molecular cargoes remains a challenge,because the leakage of drugs before ultrasound irradiation might cause side effects such as the undesired toxicity and the decrease of effective drug concentration at the target ***,we present a novel strategy to tackle these shortcomings by employing nanodrugs which refers to nanoparticles coated with small molecule *** showed that the drug leakage was prevented when encapsulating the nanodrug in ***,the fabricated drug delivery system was responsive not only to unfocused high-intensity ultrasound but also to the clinically relevant high-intensity focused ***,as a proof of concept,we showed that the antibacterial activity of the nanodrug@Microcapsules could be activated by applying ultrasound in *** results may provide new insights into the development of ultrasound triggered small molecule drug delivery assisted by metallic nanoparticles.

关键词： microcapsules vancomycin-nanodrug sonication drug release

Multiscale engineered artificial compact bone via bidirectional freeze-driven lamellated organization of mineralized collagen microfibrils

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Bioactive Materials 2024年第10期40卷 168-181页

作者： Lingwenyao Kong Yonggang Zhao Yang Xiong junlin chen Shuo Wang Ziming Yan Huibin Shi Zhanli Liu Xiumei Wang State Key Laboratory of New Ceramics and Fine Processing Key Laboratory of Advanced Materials of Ministry of EducationSchool of Materials Science and EngineeringTsinghua UniversityBeijing100084China State Key Laboratory for Performance and Structure Safety of Petroleum Tubular Goods and Equipment Materials Tubular Goods Research Institute of CNPCXi’an710077China Department of Orthopedics Dongzhimen HospitalBeijing University of Chinese MedicineBeijingChina School of Aerospace Engineering Tsinghua UniversityBeijing100084China

Bone,renowned for its elegant hierarchical structure and unique mechanical properties,serves as a constant source of inspiration for the development of synthetic ***,achieving accurate replication of bone features in artificial materials with remarkable structural and mechanical similarity remains a significant *** this study,we employed a cascade of continuous fabrication processes,including biomimetic mineralization of collagen,bidirectional freeze-casting,and pressure-driven fusion,to successfully fabricate a macroscopic bulk material known as artificial compact bone(ACB).The ACB material closely replicates the composition,hierarchical structures,and mechanical properties of natural *** demonstrates a lamellated alignment of mineralized collagen(MC)microfibrils,similar to those found in natural ***,the ACB exhibits a similar high mineral content(70.9%)and density(2.2 g/cm3)as natural cortical bone,leading to exceptional mechanical properties such as high stiffness,hardness,and flexural strength that are comparable to those of natural ***,the ACB also demonstrates excellent mechanical properties in wet,outstanding biocompatibility,and osteogenic properties in vivo,rendering it suitable for a broad spectrum of biomedical applications,including orthopedic,stomatological,and craniofacial surgeries.

关键词： Artificial compact bone Bidirectional freeze-casting Mineralized collagen microfibril Hierarchical structures

A bio-feedback-mimicking electrode combining real-time monitoring and drug delivery

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The Innovation 2024年第6期5卷 69-79页

作者： Shuaiyin Liu Tianqin Ning junlin chen Yanzhe Fu Jiebo Li Jinyu Li Xufeng Niu Yubo Fan Key Laboratory of Biomechanics and Mechanobiology(Beihang University) Ministry of EducationBeijing Advanced Innovation Center for Biomedical EngineeringSchool of Biological Science and Medical EngineeringBeihang UniversityBeijing 100083China Department of Orthopedic Dongzhimen HospitalBeijing University of Chinese MedicineBeijing 100007China School of Engineering Medicine Beihang UniversityBeijing 100083China

Effective disease management based on real-time physiological changes presents a significant clinical challenge.A flexible electrode system integrating diagnosis and treatment can overcome the uncertainties associated with treatment progress during localized *** this study,we develop a system featuring a biomimetic feedback regulation mechanism for drug delivery and real-time *** prevent drug leakage,the system incorporates a magnesium(Mg)valve in the outer layer,ensuring zero leakage when drug release is not required.

关键词： electrode system treatment

Neural stimulation and modulation with subcellular precision by optomechanical bio-dart

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Light(Science & Applications) 2024年第11期13卷 2668-2679页

作者： Guoshuai Zhu Jianyun Xiong Xing Li Ziyi He Shuhan Zhong junlin chen Yang Shi Ting Pan Li Zhang Baojun Li Hongbao Xin Guangdong Provincial Key Laboratory of Nanophotonic Manipulation Institute of NanophotonicsCollege of Physics and Optoelectronic EngineeringJinan UniversityGuangzhou 511443China Key Laboratory of CNS Regeneration(Ministry of Education) Guangdong-Hong Kong-Macao Institute of CNS RegenerationJinan UniversityGuangzhou 510632China

Neural stimulation and modulation at high spatial resolution are crucial for mediating neuronal signaling and plasticity,aiding in a better understanding of neuronal dysfunction and neurodegenerative ***,developing a biocompatible and precisely controllable technique for accurate and effective stimulation and modulation of neurons at the subcellular level is highly ***,we report an optomechanical method for neural stimulation and modulation with subcellular precision using optically controlled *** bio-dart is obtained from the tip of sunflower pollen grain and can generate transient pressure on the cell membrane with submicrometer spatial resolution when propelled by optical scattering force controlled with an optical fiber probe,which results in precision neural stimulation via precisely activation of membrane mechanosensitive ion ***,controllable modulation of a single neuronal cell,even down to subcellular neuronal structures such as dendrites,axons,and soma,can be *** bio-dart can also serve as a drug delivery tool for multifunctional neural stimulation and ***,our optomechanical bio-darts can also be used for in vivo neural stimulation in larval *** strategy provides a novel approach for neural stimulation and modulation with sub-cellular precision,paving the way for high-precision neuronal plasticity and neuromodulation.

关键词： stimulation neural precisely

A New Material of Lindera (Lauraceae) of the Late Pliocene from Tengchong, Yunnan and the Genus' Biogeography Significance

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Acta Geologica Sinica(English Edition) 2013年第3期87卷 690-706页

作者： DAO Kequn chen junlin JIN Peihong DONG Chong YANG Yi XU Xiaohui WU Jingyu XIE Sanping LIN Zhicheng SUN Bainian School of Earth Sciences and Key Laboratory of Mineral Resources in Western China (Gansu Province) Lanzhou University School of Petroleum Engineering Chongqing University of Science & Technology

Lindera is a large genus of graceful, pleasantly scented and common native trees and shrubs of southern China and neighboring regions of SE Asia. There is a well-documented Cenozoic fossil record not only in these regions but also from elsewhere. A new fossil leaf record has been found in diatomite beds from the Upper Pliocene Mangbang Formation of Tuantian, Tengchong County, Yunnan. The leaves are identified and assigned to Lindera acuminatissima K. Q. Dao et B. N. Sun sp. nov., by comparing their leaf architecture and epidermal characteristics with those of 51 extant Lauraceae species and with 15 known fossil Lindera taxa. The specimens have well-preserved cuticles, with typical leaf architecture and epidermal characteristics of the Lanraceae, including entire leaf margin, intramarginal veins, basal ternate acrodromous primary veins, one-cell trichome base, paracytic stomatal apparatus, sunken guard cells, subsidiary hardly staining cells and presence of oil cells. These characteristics are consistent with Lindera sect. Daphnidium but are different from reported fossil and extant species of Lindera. The cuticles of Lindera are fragile and delicate with only three Lindera fossils reported based on this tissue. In terms of paleobiogeography, the fossil record indicates that Lindera is distributed in high- to mid-latitude regions of the Late Cretaceous to Paleocene northern hemisphere. Coincidentally, the records of Lindera located on both sides of the Bering Land Bridge possibly support the hypothesis that ancient plants extended via transcontinental exchanges through the Bering Corridor. In the Eocene, ancient Lindera spread to Europe through the Northern Degeer Route and the Southern Thulian Route. At the same time, ancient Lindera spread into Central Asia. Climatic changes and tectonization since the Neogene prevented the propagation of Lindera throughout Asia, North America and Europe, and hence the distribution areas have just regressed to the low-latitude regi

关键词： paleobotany fossil leaves cuticle biogeography Piacenzian Yunnan province