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Highly Improved Creep Resistance in Polypropylene Through Thermally Reduced Graphene Oxide and Its Creep Lifetime Prediction

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Chinese Journal of Polymer Science 2024年第2期42卷 256-266,I0010页

作者： can-can zhang Jun-Long yang Ya-Jiang Huang Guang-Xian Li College of Polymer Science and Engineering State Key Laboratory of Polymer Materials Engineering of ChinaSichuan UniversityChengdu610065China

Polypropylene(PP) exhibits suboptimal creep resistance due to the presence of methyl groups on its main chain, leading to irregular chain segment distribution, diminished inter-chain interaction, and crystallinity. This structural feature causes chain slippage in PP under stress,significantly constraining its service lifetime. In this study, thermally reduced graphene oxide(TrGO) nanosheets were incorporated into the PP matrix, yielding a nanocomposite with exceptional creep resistance performance. Results demonstrated that at a stress of 25 MPa, a 2.0 wt% TrGO content could enhance the creep failure lifetime of PP by 21.5 times compared to neat PP. Rheology, transmission electron microscopy(TEM),and scanning electron microscopy(SEM) characterization techniques were employed to analyze the mechanism of TrGO's influence on PP's creep behavior. It was observed that when TrGO content exceeded 1.0 wt%, an effective particle network structure formed within the PP matrix. This homogeneously dispersed TrGO-formed particle network structure restricted the migration and rearrangement of PP molecular chains, enabling prolonged stress resistance without structural failure. By combining the time-strain superposition method with the critical failure strain as a criterion, generalized creep compliance curves for PP and its composites were established, facilitating the prediction of material creep failure lifetimes, with a strong agreement between experimental and predicted lifetime values. This research proposes a novel strategy aimed at developing polypropylene materials and products with enhanced long-term stability and durability, thus extending service life, reducing failure risk, and broadening their potential across various application domains.

关键词： Thermally reduced graphene oxide Polypropylene Creep failure and lifetime prediction

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Highly Hydrolysis-Resistant Polyimide Fibers Prepared by Thermal Crosslinking with Inherent Carboxyl Groups

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Chinese Journal of Polymer Science 2024年第2期42卷 247-255,I0010页

Easy hydrolysis in alkaline environments limits the use of polyimide fibers in environmental protection. The hydrolysis resistance levels of polyimide fibers can be improved by crosslinking of the macromolecular chains. In this work, crosslinked polyimide fibers(CPI fibers) were produced by intrinsic carboxyl decarboxylation for the first time. The thermal stability of the polyimide fibers containing the intrinsic carboxyl groups(PIC fibers) was studied, and the temperature of the decarboxylation-crosslinking reaction was determined to be 450 ℃. The PIC fibers were hotdrawn to initiate thermal crosslinking of the carboxyl groups and molecular chain orientation at high temperature. The CPI fibers had high tensile strengths(0.72-1.46 GPa) and compressive strengths(401-604 MPa). The oriented macromolecules and chemically crosslinked structure improved the tightness of the molecular chains and endowed the CPI fibers with excellent hydrolytic resistance. The CPI-50 fiber did not dissolve in a 0.5 wt% NaOH solution during heating at 90 ℃ for 10 h, and the tensile strength retention reached 87% when treated in 0.5 wt% NaOH solutions at 90 ℃ for 1 h, providing a guarantee for its application in alkaline corrosive environments.

关键词： Polyimide Carboxyl group Crosslinking Hydrolysis-resistance

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An Ultra-Compact Broadband Polarizing Beam Splitter Utilizing Hybrid Plasmonic Waveguide

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China Communications 2023年第6期20卷 49-59页

作者： Li zhang Jiaqi Liu can Pan Yatao yang College of Electronics and Information Engineering Shenzhen UniversityShenzhen 518000China

Polarizing beam splitter has rather significant applications in polarization diversity circuits and polarization multiplexing systems.In this paper,we present an asymmetric polarizing beam splitter utilizing hybrid plasmonic waveguide.The special hybrid structure with a hybrid waveguide and a dielectric waveguide can limit the energy of TE and TM modes to a different layer.Therefore,we can achieve beam splitting by adjusting the corresponding parameters of the two waveguides.First,we studied the influences of different structure parameters on the real part of the effective mode refractive index of the two waveguides,and obtained a set of parameters that satisfy the condition of strong coupling of TM mode and weak coupling of TE mode.Then,the performance of our proposed polarizing beam splitter is evaluated numerically.The length of the coupling section is only 4.1μm,and the propagation loss of TM and TE modes is 0.0025 d B/μm and 0.0031 d B/μm respectively.Additionally,the extinction ratios of TM and TE modes are 10.62 d B and 12.55 d B,respectively.Particularly,the proposed device has excellent wavelength insensitivity.Over the entire C-band,the fluctuation of the whole normalized output power is less than 0.03.In short,our proposed asymmetric polarizing beam splitter features ultra-compactness,low propagation loss,and broad bandwidth,which would provide promising applications in polarization multiplexing system and polarization diversity circuits relevant to optical interconnection.

关键词： polarizing beam splitter hybrid plasmonic waveguide directional coupler polarization multiplexing systems

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Graphene-based nanomaterials for cancer therapy and anti-infections

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Bioactive Materials 2022年第8期7卷 335-349页

作者： Yan Wang Juan Li Xiaobin Li Jinping Shi Zhaotan Jiang Can Yang Zhang School of Physics Beijing Institute of TechnologyBeijing100081China Advanced Research Institute for Multidisciplinary Science Beijing Institute of TechnologyBeijing100081China Institute of Biopharmaceutical and Health Engineering Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China

Graphene-based nanomaterials(GBNMs)has been thoroughly investigated and extensively used in many biomedical fields,especially cancer therapy and bacteria-induced infectious diseases treatment,which have attracted more and more attentions due to the improved therapeutic efficacy and reduced reverse effect.GBNMs,as classic two-dimensional(2D)nanomaterials,have unique structure and excellent physicochemical properties,exhibiting tremendous potential in cancer therapy and bacteria-induced infectious diseases treatment.In this review,we first introduced the recent advances in development of GBNMs and GBNMs-based treatment strategies for cancer,including photothermal therapy(PTT),photodynamic therapy(PDT)and multiple combination therapies.Then,we surveyed the research progress of applications of GBNMs in anti-infection such as antimicrobial resistance,wound healing and removal of biofilm.The mechanism of GBNMs was also expounded.Finally,we concluded and discussed the advantages,challenges/limitations and perspective about the development of GBNMs and GBNMs-based therapies.Collectively,we think that GBNMs could be potential in clinic to promote the improvement of cancer therapy and infections treatment.

关键词： Graphene Phototherapy cancer therapy Anti-infection 2D materials

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Composite rock-breaking of high-pressure CO_(2)jet&polycrystallinediamond-compact(PDC)cutter using a coupled SPH/FEM model

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International Journal of Mining Science and Technology 2022年第5期32卷 1115-1124页

作者： can Cai Pei zhang Daping Xu Xianpeng yang Yingfang Zhou School of Mechanical Engineering Southwest Petroleum UniversityChengdu 610500China Key Laboratory of Groundwater Resources and Environment Jilin UniversityMinistry of EducationChangchun 130021China Laboratory of High-pressure Jet Theory and Application Technology Southwest Petroleum UniversityChengdu 610599China School of Engineering University of AberdeenAberdeen AB243FXUnited Kingdom School of Intelligent Manufacturing Panzhihua UniversityPanzhihua 617000China

CO_(2) drilling is a promising underbalance drilling technology with great advantages,such as lower cutting force,intense cooling and excellent lubrication.However,in the underbalance drilling,the mechanism of the coupling CO_(2) jet and polycrystalline-diamond-compact(PDC)cutter are still unclear.Whereby,we established a coupled smoothed particle hydrodynamics/finite element method(SPH/FEM)model to simulate the composite rock-breaking of high-pressure CO_(2) jet&PDC cutter.Combined with the experimental research results,the mechanism of composite rock-breaking is studied from the perspectives of rock stress field,cutting force and jet field.The results show that the composite rock-breaking can effectively relieve the influence of vibration and shock on PDC cutter.Meanwhile,the high-pressure CO_(2) jet has a positive effect on carrying rock debris,which can effectively reduce the temperature rising and the thermal wear of the PDC cutter.In addition,the effects of CO_(2) jet parameters on composite rock-breaking were studied,such as jet impact velocity,nozzle diameter,jet injection angle and impact distance.The studies show that when the impact velocity of the CO_(2) jet is greater than 250 m/s,the CO_(2) jet could quickly break the rock.It is found that the optimal range of nozzle diameter is 1.5–2.5 mm,the best injection angle of CO_(2) jet is 60,the optimal impact distance is 10 times the nozzle diameter.The above studies could provide theoretical supports and technical guidance for composite rock-breaking,which is useful for the CO_(2) underbalance drilling and drill bit design.

关键词： C0_(2)drilling High-pressure C0_(2)jet&PDC cutter Composite rock-breaking Experimental study SPH/FEM method

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Multi-functional engineered polypeptide-based drug delivery systems for improved cancer therapy

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Green Chemical Engineering 2023年第2期4卷 173-188页

作者： Xiaobin Li Junyu Liu Haihong Chen Yaxin Chen Yi Wang Can Yang Zhang Xin-Hui Xing Institute of Biopharmaceutical and Health Engineering Shenzhen International Graduate SchoolTsinghua UniversityShenzhen518055China Institute of Biochemical Engineering Department of Chemical EngineeringTsinghua UniversityBeijing100084China MOE Key Laboratory for Industrial Biocatalysis Beijing100084China Institute of Biomedical Health Technology and Engineering Shenzhen Bay LaboratoryShenzhen440300China Center for Synthetic and Systems Biology Tsinghua UniversityBeijing100084China

With the rapid development of chemical engineering and biotechnology,polypeptide,as a promising candidate in the biomedical field,has been thoroughly investigated and extensively used as the drug delivery vehicle for diseases treatment,especially cancer,owing to the high biocompatibility,good biodegradability,versatile con-structions,and diverse functions.Engineered polypeptide-based drug delivery system(so-called EPP-DDS)can deliver the cargos to the target site via a specific recognition effect,followed by overcoming the barriers like blood brain barrier(BBB)and releasing them by responding to the microenvironment cues,to improve the therapeutic efficacy and reduce the side-effect.Herein,it's of great importance to conclude and summarize the updates on EPP-DDS developed by chemical engineering methods.In this review,we first summarized the recent updates in the manufacturing of polypeptide and preparation of EPP-DDS based on green biochemical engineering and/or synthetic processes for cancer therapy,including chemotherapy,immunotherapy,photodynamic therapy(PDT),gene therapy,and combination therapy.Then,we surveyed the research progress of inflammation-mediated cancer treatment strategies based on EPP-DDS with high anti-inflammation activity.Finally,we concluded the discovery and green production process of engineered polypeptide,challenges,and perspectives of EPP-DDS.Overall,the EPP-DDS has great potential for cancer therapy in the clinic with improved therapeutic efficacy and reduced adverse effect,which needs the innovation of green biochemical engineering for customized design and production of polypeptides.

关键词： Polypeptide Drug delivery system cancer therapy Biopharmaceutics Green biochemical engineering

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Ultra-lightweight CNN design based on neural architecture search and knowledge distillation: A novel method to build the automatic recognition model of space target ISAR images

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Defence Technology（防务技术） 2022年第6期18卷 1073-1095页

作者： Hong yang Ya-sheng zhang can-bin Yin Wen-zhe Ding Space Engineering University Beijing101416China Beijing Institute of Tracking and Telecommunications Technology China

In this paper,a novel method of ultra-lightweight convolution neural network(CNN)design based on neural architecture search(NAS)and knowledge distillation(KD)is proposed.It can realize the automatic construction of the space target inverse synthetic aperture radar(ISAR)image recognition model with ultra-lightweight and high accuracy.This method introduces the NAS method into the radar image recognition for the first time,which solves the time-consuming and labor-consuming problems in the artificial design of the space target ISAR image automatic recognition model(STIIARM).On this basis,the NAS model’s knowledge is transferred to the student model with lower computational complexity by the flow of the solution procedure(FSP)distillation method.Thus,the decline of recognition accuracy caused by the direct compression of model structural parameters can be effectively avoided,and the ultralightweight STIIARM can be obtained.In the method,the Inverted Linear Bottleneck(ILB)and Inverted Residual Block(IRB)are firstly taken as each block’s basic structure in CNN.And the expansion ratio,output filter size,number of IRBs,and convolution kernel size are set as the search parameters to construct a hierarchical decomposition search space.Then,the recognition accuracy and computational complexity are taken as the objective function and constraint conditions,respectively,and the global optimization model of the CNN architecture search is established.Next,the simulated annealing(SA)algorithm is used as the search strategy to search out the lightweight and high accuracy STIIARM directly.After that,based on the three principles of similar block structure,the same corresponding channel number,and the minimum computational complexity,the more lightweight student model is designed,and the FSP matrix pairing between the NAS model and student model is completed.Finally,by minimizing the loss between the FSP matrix pairs of the NAS model and student model,the student model’s weight adjustment is completed.Thus the ultra-lightweight and

关键词： Space target ISAR image Neural architecture search Knowledge distillation Lightweight model

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Identifying Supercooled Liquid Water in Cloud Based on Airborne Observations: Correlation of Cloud Particle Number Concentration with Icing Probability and Proportion of Spherical Particles

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Journal of Meteorological Research 2022年第4期36卷 574-585页

作者： Yuquan ZHOU can SONG Miao CAI Siyao LIU yang GAO Rong zhang CMA Cloud–Precipitation Physics and Weather Modification Key Laboratory(CPML) Beijing 100081 Weather Modification Center of Henan Province Zhengzhou 450000 College of Global Change and Earth System Science Beijing Normal UniversityBeijing 100875

Identifying supercooled liquid water(SLW)in clouds is critical for weather modification,aviation safety,and atmospheric radiation calculations.Currently,aircraft identification in the SLW area mostly depends on emprical estimation of cloud particle number concentration(N_(c))in China,and scientific verification and quantitative identification criteria are urgently needed.In this study,the observations are from the Fast Cloud Droplets Probe,Rosemount ice detector(RICE),and Cloud Particle Imager(CP_(i))onboard a King Air aircraft during seven flights in 2018 and 2019 over central and eastern China.Based on this,the correlation among N_(c),the proportion of spherical particles(P_(s)),and the probability of icing(P_(i))in supercooled stratiform and cumulus-stratus clouds is statistically analyzed.Subsequently,this study proposes a method to identify SLW areas using N_(c) in combination with ambient temperature.The reliability of this method is evaluated through the true skill statistics(TSS)and threat score(TS)methods.Numerous airborne observations during the seven flights reveal a strong correlation among Nc,P_(s),and P_(i)at the temperature from 0 to−18°C.When Nc is greater than a certain threshold of 5 cm^(−3),there is always the SLW,i.e.,P_(i)and P_(s)are high.Evaluation results demonstrate that the TSS and TS values for Nc=5 cm^(−3)are higher than those for Nc5 cm^(−3))corresponds to a higher SLW identification hit rate and a higher SLW content.Therefore,Nc=5 cm^(−3)can be used as the minimum criterion for identifying the SLW in clouds at temperature lower than 0°C.The SLW identification method proposed in this study is especially helpful in common situations where aircraft are equipped with only Nc probes and without the CP_(i)and RICE.

关键词： supercooled liquid water(SLW) icing probability cloud particle shape cloud particle number concentration

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Nest sanitation facilitates egg recognition in the common tailorbird, a plaintive cuckoo host

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Zoological Research 2019年第5期40卷 466-470页

作者： Chang-zhang Feng can-Chao yang Wei Liang Ministry of Education Key Laboratory for Ecology of Tropical Islands College of Life Sciences Hainan Normal University

Nest sanitation is a ubiquitous behavior in birds and functions to remove foreign objects that accidentally have fallen into their nests. In avian brood parasitism, the host’s ability to recognize and reject parasitic eggs is a specific anti-parasitic behavior. Previous studies have shown that egg recognition may have evolved from nest sanitation behavior;however, few studies have offered evidence in support of this hypothesis. In the current study, we added one real white egg and one model egg to the nests of common tailorbirds (Orthotomus sutorius), the main host of plaintive cuckoos (Cacomantis merulinus), to explore the relationship between egg recognition ability in hosts and nest sanitation behavior. Results showed that common tailorbirds rejected both non-mimetic blue model eggs and mimetic white model eggs at a similar rate of 100%, but only rejected 16.1% of mimetic real white eggs. The egg rejection behavior of common tailorbirds towards both real and model eggs was consistent. However, when both blue model eggs and real white eggs were simultaneously added to their nests, the probability of rejecting the mimetic real white egg increased to 50%. The addition of blue model eggs not only increased the occurrence of nest sanitation behavior but also increased the ability to recognize and reject parasitic eggs. This suggests that nest sanitation may facilitate egg rejection in common tailorbird hosts.

关键词： Nest sanitation egg recognition a plaintive cuckoo host

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Numerical analysis and experimental validation of surface roughness and morphology in honing of Inconel 718 nickel-based superalloy

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Advances in Manufacturing 2023年第1期11卷 130-142页

作者： Chang-Yong yang Zhi Wang Hao Su Yu-can Fu Nian-Hui zhang Wen-Feng Ding Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology Nanjing University of Aeronautics and AstronauticsNanjing210016People’s Republic of China College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing210016People’s Republic of China

Honing is an important technology for machining onboard system parts.The parts are usually made of difficult-to-machining materials,e.g.,Inconel 718 superalloy.Honing can improve the finishing accuracy and surface quality.However,the selection of the honing parameters was primarily based on the results of a large number of experiments.Therefore,the establishment of a reliable model is needed to predict the honed surface roughness and morphology,and offers a theoretical direction for the choice of parameters.In the present study,a numerical simulation model was constructed for analysis of the honing process by Python.The oilstone,workpiece surface morphology and motion trajectory were discretized by Python,and the machined surface was obtained by trajectory interference.Firstly,based on the statistical analysis of the surface topography of oilstone,the shape of grains was simplified and the surface topography of oilstone was built accordingly.Then,the initial surface morphology of the workpiece was constructed and the trajectory of grains on the workpiece surface was analyzed,which showed the distribution of the removed material.Meanwhile,the plastic deformation of material was analyzed in the simulation model.The critical depth of three stages of contact between grains and workpiece was calculated by the theoretical formula:scratching,ploughing and cutting.By analyzing the distribution of bulge,the plastic deformation in ploughing and cutting stage was studied.Further,the simulated results of honed surface roughness and morphology were validated and agreed reasonably well with the honing experiment.Finally,the effects of honing process parameters,including grain size,tangential speed,axial speed,radial speed and abrasive volume percentage,on the surface roughness of the workpiece were analyzed by the simulation model.

关键词： Numerical analysis Surface roughness Plastic deformation Morphology

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