Environmental contamination has been caused by petroleum-based polymeric materials in the melt deposition process.Nowadays biodegradable materials have been widely used in the fused deposition modeling(FDM)industry,su...Environmental contamination has been caused by petroleum-based polymeric materials in the melt deposition process.Nowadays biodegradable materials have been widely used in the fused deposition modeling(FDM)industry,such as polylactic acid(PLA).However,internal complex thermal stress and deformations in part caused by an uneven distribution of PLA filament deposition temperatures during FDM,which will seriously affect the geometric accuracy of the printed part.In order to reduce material waste and environmental pollution during the printing process,the accuracy of PLA part can be improved.Herein,numerical simulation was carried out to investigate the temperature field and stress field during the building and cooling process of cuboid specimens.The effects of printing path on the thermal stress and temperature field during the building process were mainly studied.The results show that the printing path has a significant effect on the stress distribution.The most uni-form stress distribution and the smallest deformation were obtained using the Zig Zag printing path.Finally,the residual stress during the cooling process was collected using strain gauges embedded at the mid-plane of the FDM built cuboid specimens.The simulation results are consistent with the experimental results.展开更多
High precision control of substrate tension is the premise and guarantee for producing high-quality products in roll-to-roll precision coating machine.However,the complex relationships in tension system make the probl...High precision control of substrate tension is the premise and guarantee for producing high-quality products in roll-to-roll precision coating machine.However,the complex relationships in tension system make the problems of decoupling control difficult to be solved,which has limited the improvement of tension control accuracy for the coating machine.Therefore,an ADRC parameters self-tuning decoupling strategy based on RBF neural network is proposed to improve the control accuracy of tension system in this paper.Firstly,a global coupling nonlinear model of the tension system is established according to the composition of the coating machine,and the global coupling model is linearized based on the first-order Taylor formula.Secondly,according to the linear model of the tension system,a parameters self-tuning decoupling algorithm of the tension system is proposed by integrating feedforward control,ADRC and RBF.Finally,the simulation results show that the proposed tension control strategy has good decoupling control performance and effectively improves the tension control accuracy for the coating machine.展开更多
Printing quality evaluation is an important means to check whether prints are qualfied.However,the urrent printing quality evaluation system for gravure decorative paper is not perfect.In order to solve this problem,a...Printing quality evaluation is an important means to check whether prints are qualfied.However,the urrent printing quality evaluation system for gravure decorative paper is not perfect.In order to solve this problem,a method for evaluating quality of decorative paper based on analytical hierarchy process(AHP)and the entropy weight method(EWM)model is proposed in this paper.So as to verify the proposed model,decorative paper of different grades was selected as the experimental objects.Firstly,the data about five indices eflecting printing quality were measured.Secondly,the evaluation model was used to assign weights to the indices,and scores in each index were calculated according to scoring tables.Finally,the evalua tion scores were statistically analyzed.The results of data analysis showed that the 95% confidence intervals and coefficients of variation were small.The average error of the evaluation system was 0.2061.It indicates that the model can stably distinguish decorative paper of diferent grades,accuracy of which is high.The research in this paper can provide reference to the quality improvement of decorative paper and the printing quality evaluation of other paper.展开更多
Cellulose plays a key role in abundant organic natural materials meeting the increasing demand for green and biocompatible products.The highly crystalline nanoscale component of cellulose nanocrystals has recently att...Cellulose plays a key role in abundant organic natural materials meeting the increasing demand for green and biocompatible products.The highly crystalline nanoscale component of cellulose nanocrystals has recently attracted great attention due to the versatile performance as filler or matrix in producing functional materials.In this work,we prepared the waterborne polyurethane via a prepolymer process,and obtained cellulose and cellulose nanocrystals from waste paper via a facile acid hydrolysis process.After that,the cellulose nanocrystals were assembled into film and mixed with polyurethane to prepare flexible polyurethane/cellulose nanocrystals composite membrane with different soaking time.The correlation between the bulk structure and applied properties including thermal resistance and mechanical property was investigated by using Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),differential scanning calorimetry(DSC)and folding test.The structure analysis indicates that cellulose nanocrystals prepared from used paper have a quality similar to that of commercial cellulose.Meanwhile,the cellulose nanocrystals have been mixed with polyurethane uniformly.Polyurethane can significantly benefit to the thermal resistance and mechanical property of the cellulose nanocrystals film.The polyurethane/cellulose nanocrystals composite membrane present good flexibility and may hold a significantly potential application as visual and flexible material.展开更多
Liquid-solid extrusion directly following vacuum infiltration(LSEVI)is an infiltration-extrusion integrated forming technique,and transverse weld between upper residual magnesium alloy and magnesium matrix composites ...Liquid-solid extrusion directly following vacuum infiltration(LSEVI)is an infiltration-extrusion integrated forming technique,and transverse weld between upper residual magnesium alloy and magnesium matrix composites is a common internal defect,which can severely reduce the yield of composite products.To improve current understanding on the mechanism of transverse welding phenomenon,a thermo-mechanical numerical model of LSEVI for magnesium matrix composites was developed.The formation of transverse weld during extrusion was visualized using finite element simulation method,and the formation mechanism was discussed from the aspect of velocity field using a point tracking technique.The simulation results were verified by the experimental results in term of weld shape.展开更多
Waste packaging polyethylene(WPE) was used to modify raw asphalt by melt blending the components at 190 ℃ for 1 h in a simple mixer and subsequently machining them at 120 ℃ for 1 h in a highspeed shearing machine.Th...Waste packaging polyethylene(WPE) was used to modify raw asphalt by melt blending the components at 190 ℃ for 1 h in a simple mixer and subsequently machining them at 120 ℃ for 1 h in a highspeed shearing machine.The effect of modification on the degree of the penetration,the softening point and the ductility of the asphalt was studied using fluorescent microscopy,infrared spectrometry,component changes and various other techniques.The experimental results showed that no chemical reactions took place in the components themselves(saturate,aromatic,asphaltene and resin) during the modifications.The softening point and penetration of the asphalt were found to be closely related to the resulting contents of the asphaltene,saturate and resin components.In addition,aromatics were identified as having the greatest impact on the ductility of the asphalt.展开更多
A facile method,focusing on emulsification,chain extension and dispersion process in preparing waterborne polyurethane,was developed to prepare emulsion with rod-like nanoparticles.The facile method involves a water a...A facile method,focusing on emulsification,chain extension and dispersion process in preparing waterborne polyurethane,was developed to prepare emulsion with rod-like nanoparticles.The facile method involves a water addition procedure by in situ generated water to react with polyurethane prepolymer instead of the external water addition process.As a comparison,waterborne polyurethane was synthesized through the external water addition process.According to the characterization methods including FTIR,1H-NMR,TEM and water swelling experiments,it is suggested there are two kinds of hydrogen bonds interactions in hard/soft domain of the novel polyurethane,and the phase separation of hard/soft domains increases significantly.The morphology of the two polyurethanes was quite different(nanorods and spherical particles,respectively),presenting a different surface property.In addition,the water swelling of the novel polyurethane indicates that it holds significant potential application as degradable material.展开更多
Greenhouse gas emissions from waste plastics have caused global warming all over the world,which has been a central threat to the ecological environment for humans,flora and fauna.Among waste plastics,waste polyethyle...Greenhouse gas emissions from waste plastics have caused global warming all over the world,which has been a central threat to the ecological environment for humans,flora and fauna.Among waste plastics,waste polyethylene terephthalate(PET)is attractive due to its excellent stability and degradation-resistant.Therefore,merging China’s carbon peak and carbon neutrality goals would be beneficial.In this review,we summarize the current state-of-the-art of carbon emission decrease from a multi-scale perspective technologically.We suggest that the carbon peak for waste PET can be achieved by employing the closed-loop supply chain,including recycling,biomass utilization,carbon capture and utilization.Waste PET can be a valuable and renewable resource in the whole life cycle.Undoubtedly,all kinds of PET plastics can be ultimately converted into CO_(2),which can also be feedstock for various kinds of chemical products,including ethyl alcohol,formic acid,soda ash,PU,starch and so on.As a result,the closed-loop supply chain can help the PET plastics industry drastically reduce its carbon footprint.展开更多
A method of restoring scratches on old paintings is proposed,and the corresponding high-accuracy output workflow is also developed.Firstly the scanner is selected as an input device to get the RGB(red,green,blue)image...A method of restoring scratches on old paintings is proposed,and the corresponding high-accuracy output workflow is also developed.Firstly the scanner is selected as an input device to get the RGB(red,green,blue)image of the painting,and for the purpose of capturing high-quality image,scanner characterization is done by using neural network.And then the scratches on the RGB image are restored with the technology of digital inpainting,while the inpainting algorithm is mainly based on gradient vector and fast marching method.Finally the restored image is output with a printer,which is calibrated by using the high order polynomial regression method.In experiment the new replicated painting is well restored in the scratched areas,as well as keeps high resemblance with the original painting.展开更多
Flexible sensors are attractive due to potential applications in body exercise and ambient gas monitoring systems.Cellulose and its derivatives have combined superiorities such as intrinsic and structural flexibility,...Flexible sensors are attractive due to potential applications in body exercise and ambient gas monitoring systems.Cellulose and its derivatives have combined superiorities such as intrinsic and structural flexibility,ease of chemical functionalization,moisture sensitivity,and mechanical stability,enabling them to be promising candidates as flexible supporting substrates and flexible sensitive materials.Significant progress consequently has been achieved to improve mechanical,electrical,and chemical performance.The latest advance in materials synthesis,structure design,fabrication control,and working mechanism of novel cellulose-based flexible sensors are reviewed and discussed,including strain sensors,humidity sensors,and harmful gas sensors.Various strategies were summarized to enhance sensor performance by surface group modifications,inorganic and organic conducting fillers optimization,multilayer structure design.Newly emerged processing techniques of self-assembly,vacuum filtration,and 3D printing were introduced as well to construct multiscale microstructures.The integration of multiple sensors toward smart and healthy exercise monitoring system is briefly reviewed.The facing challenges and future opportunities of cellulose-based flexible sensors were discussed and proposed at the end.This review provides inspiration and guidelines on how to design and fabricate cellulose-based flexible sensors.展开更多
Dielectric polymer film capacitors with a high-power density as well as efficient charge and discharge rates have great potential for application to fulfill the miniaturized and lightweight requirements of the electro...Dielectric polymer film capacitors with a high-power density as well as efficient charge and discharge rates have great potential for application to fulfill the miniaturized and lightweight requirements of the electronic and stationary power systems.It was reported that the elastic recovery rate and energy storage density of poly(vinylidene fluoride-chlorotrifluoroethylene)[P(VDF-CTFE)]polymer film can be enhanced through thermostatic uniaxial stretching.But it is unknown about the relationship between the stretching rate and above properties.In this study,we investigated the effect of different stretching rates on the conformation,elastic recovery,dielectric constant,and energy storage density of stretched P(VDF-CTFE)polymer films.It was found that the stretching rate significantly affected the formation of polarβ-crystal phase,causing different dielectric properties.The degrees of elastic recovery of P(VDF-CTFE)film vary with stretching rates.Among them,the elastic recovery rate of the P(VDF-CTFE)94/6 film is 46.5%at a stretching rate of 15 mm/min,the dielectric constant is 12.25 at 100 Hz,and the energy density reaches 3.95 J/cm^(3) with the energy loss of 39%at 200 MV/m field.展开更多
The insulation degradation in polymeric backsheets has been identified as a main cause of catastrophic accidents induced by short circuit or ground faults in photovoltaic module.To ensure quality,the photovoltaic indu...The insulation degradation in polymeric backsheets has been identified as a main cause of catastrophic accidents induced by short circuit or ground faults in photovoltaic module.To ensure quality,the photovoltaic industry is therefore faced with urgent demand in discovering degradation mechanisms.Moreover,the development of environmental-friendly backsheets and the establishment of backsheets recycling specifications are vital to fulfilling the requirements of a future reliable photovoltaic system with improved productivity.In this review,we innovatively summarize the detection methods of insulation deterioration from the viewpoints of spectroscopic,thermal and mechanical approaches.The corresponding ambient conditions in measurement and their accelerating effect on the degradation of photovoltaic backsheets are discussed.Subsequently,emerging novel materials and structures for enhancing insula-tion properties,antiaging performance and optical-electrical energy conversion efficiency of photovoltaic cell are summarized.It offers a comprehensive strategy to design materials with optimal structures in photovoltaic module for a future zero-carbon energy system.展开更多
It is important to monitor the intra-/extracellular concentration of hydrogen peroxide(H_(2)O_(2))in biological processes.However,miniaturized devices that enable portable and accurate H_(2)O_(2)measurement are still ...It is important to monitor the intra-/extracellular concentration of hydrogen peroxide(H_(2)O_(2))in biological processes.However,miniaturized devices that enable portable and accurate H_(2)O_(2)measurement are still in their infancy because of the difficulty of developing facile sensing strategies and highly integrated sensing devices.In this work,portable H_(2)O_(2)sensors based on Pt-Ni hydrogels with excellent peroxidase-like and electrocatalytic activities are demonstrated.Thus,simple and sensitive H_(2)O_(2)sensing is achieved through both colorimetric and electrochemical strategies.The as-fabricated H_(2)O_(2)sensing chips exhibit favorable performance,with low detection limits(0.030μM&0.15μM),wide linearity ranges(0.10μM-10.0 mM&0.50μM-5.0 mM),outstanding long-term stability(up to 60 days),and excellent selectivity.With the aid of an M5stack development board,portable visual and electrochemical H_(2)O_(2)sensors are successfully constructed without complicated and expensive equipment or professional operators.When applied to the detection of H_(2)O_(2)released from HeLa cells,the results obtained by the developed sensors are in good agreement with those from an ultraviolet‒visible spectrophotometer(UV‒vis)(1.97μM vs.2.08μM)and electrochemical station(1.77μM vs.1.84μM).展开更多
Thermochromic material is a kind of smart material whose color will vary as the result of the phase transition caused by the temperature change. The characteristics of thermochromic materials are the memory functions ...Thermochromic material is a kind of smart material whose color will vary as the result of the phase transition caused by the temperature change. The characteristics of thermochromic materials are the memory functions to the temperature, having great potential applications in aerospace, military, anticounterfeiting technology, construction and other fields. In recent years, many kinds of thermochromic materials have been prepared by different methods and their discoloration mechanisms are various according to published literatures. In this paper, the classification, discoloration mechanism, preparation methods, application fields and development trend of thermochromic materials are reviewed.展开更多
A synthesis strategy of fluorescent carbon quantum dots(CQDs) with high quantum yield(QY) using aqua mesophase pitch(AMP) as the carbon source has been developed via the hydrothermal method in this study. The hydrothe...A synthesis strategy of fluorescent carbon quantum dots(CQDs) with high quantum yield(QY) using aqua mesophase pitch(AMP) as the carbon source has been developed via the hydrothermal method in this study. The hydrothermal temperature and soaking time have important effects on the morphology and QY of CQDs. As-prepared CQDs at 120℃ holding for 24 h(CQDs-120-24) have the uniform size of about 2.8 nm, and the QY can reach 27.6%. The obtained CQDs are successfully modified with ammonia and thionyl chloride, respectively, and they exhibit an excellent photocatalytic performance on degrading rhodamine B(Rh B), methyl blue(MB) and indigo carmine(IC). Importantly, the degradation percentage of N-CQDs on Rh B under natural light for 4 h reaches 97% with the degradation rate constant of 0.02463 min^(-1) and it can maintain 93% after repetitively used 5 times. The results indicate that these as-prepared CQDs have the potential application in degrading organic dyes.展开更多
Anionomer-type waterborne polyurethane dispersions(PUDs) were obtained from poly(propylene glycol)(PPG), isophorone diisocyanate(IPDI) and dimethylolpropionic acid(DMPA) through a modi?ed prepolymer isocyanate process...Anionomer-type waterborne polyurethane dispersions(PUDs) were obtained from poly(propylene glycol)(PPG), isophorone diisocyanate(IPDI) and dimethylolpropionic acid(DMPA) through a modi?ed prepolymer isocyanate process. Two series of polyurethanes were prepared(Groups A and B) and a new prediction model based on grey relational analysis is introduced to predict the impact order of raw materials on several properties, such as solids content, viscosity, acid number and electrolytic stability of polyurethanes. It is found that the model can successfully predict the impact of raw materials on the properties through the designed demonstration experiments. Furthermore, the results of the prediction model show that DMPA plays a key role in viscosity, partial acid values and electrolytic stability.展开更多
Multi-faults detection is a challenge for rolling bearings due to the mode mixture and coupling of multiple fault features,as well as its easy burying in the complex,non-stationary structural vibrations and strong bac...Multi-faults detection is a challenge for rolling bearings due to the mode mixture and coupling of multiple fault features,as well as its easy burying in the complex,non-stationary structural vibrations and strong background noises.In this paper,a method based on the flexible analytical wavelet transform(FAWT)possessing fractional scaling and translation factors is proposed to identify multiple faults occurred in different components of rolling bearings.During the route of the proposed method,the proper FAWT bases are constructed via genetic optimization algorithm(GA)based on maximizing the spectral correlated kurtosis(SCK)which is firstly presented and proved to be efficient and effective in indicating interested fault mode.Via using the customized FAWT bases for each interested fault mode,the original vibration measurements are decomposed into fine frequency subbands,and the sensitive subband which enhances the signal-to-noise ratio(SNR)is selected to exhibit the fault signature on its envelope spectrum.The proposed method is tested via simulated signals,and applied to analyze the experimental vibration measurements from the running roller bearings subjected to outrace,inner-race and roller defects.The analysis results validate the effectiveness of the proposed method in identifying multi-faults occurred in different components of rolling bearings.展开更多
基金funded by Shanxi Province Technology Innovation Guidance Special Project(2020QFY03-05)Shanxi Province Printing and Packaging Key Laboratory Project(16JS081).
文摘Environmental contamination has been caused by petroleum-based polymeric materials in the melt deposition process.Nowadays biodegradable materials have been widely used in the fused deposition modeling(FDM)industry,such as polylactic acid(PLA).However,internal complex thermal stress and deformations in part caused by an uneven distribution of PLA filament deposition temperatures during FDM,which will seriously affect the geometric accuracy of the printed part.In order to reduce material waste and environmental pollution during the printing process,the accuracy of PLA part can be improved.Herein,numerical simulation was carried out to investigate the temperature field and stress field during the building and cooling process of cuboid specimens.The effects of printing path on the thermal stress and temperature field during the building process were mainly studied.The results show that the printing path has a significant effect on the stress distribution.The most uni-form stress distribution and the smallest deformation were obtained using the Zig Zag printing path.Finally,the residual stress during the cooling process was collected using strain gauges embedded at the mid-plane of the FDM built cuboid specimens.The simulation results are consistent with the experimental results.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFB1707200)the Key Research and Development Program of Shaanxi Province(Grant No.2020ZDLGY14-06)the Technology Innovation Leading Program of Shaanxi Province(Grant No.2020QFY03-03).
文摘High precision control of substrate tension is the premise and guarantee for producing high-quality products in roll-to-roll precision coating machine.However,the complex relationships in tension system make the problems of decoupling control difficult to be solved,which has limited the improvement of tension control accuracy for the coating machine.Therefore,an ADRC parameters self-tuning decoupling strategy based on RBF neural network is proposed to improve the control accuracy of tension system in this paper.Firstly,a global coupling nonlinear model of the tension system is established according to the composition of the coating machine,and the global coupling model is linearized based on the first-order Taylor formula.Secondly,according to the linear model of the tension system,a parameters self-tuning decoupling algorithm of the tension system is proposed by integrating feedforward control,ADRC and RBF.Finally,the simulation results show that the proposed tension control strategy has good decoupling control performance and effectively improves the tension control accuracy for the coating machine.
基金This work was supported in part by the National Natural Science Foundation of China under Grant 62076199the Opening Foundation of State Key Laboratory of Power System of Tractor under Grant SKT2022004+2 种基金Humanities and Social Sciences Research Planning Project of the Ministry of Education under Grant 17YJC760007in part by Doctoral Scientific Research Foundation of Xi’an University of Technology under Grant 108-451121001Shaanxi Collaborative Innovation Center of Green Intelligent Printing and Packaging.
文摘Printing quality evaluation is an important means to check whether prints are qualfied.However,the urrent printing quality evaluation system for gravure decorative paper is not perfect.In order to solve this problem,a method for evaluating quality of decorative paper based on analytical hierarchy process(AHP)and the entropy weight method(EWM)model is proposed in this paper.So as to verify the proposed model,decorative paper of different grades was selected as the experimental objects.Firstly,the data about five indices eflecting printing quality were measured.Secondly,the evaluation model was used to assign weights to the indices,and scores in each index were calculated according to scoring tables.Finally,the evalua tion scores were statistically analyzed.The results of data analysis showed that the 95% confidence intervals and coefficients of variation were small.The average error of the evaluation system was 0.2061.It indicates that the model can stably distinguish decorative paper of diferent grades,accuracy of which is high.The research in this paper can provide reference to the quality improvement of decorative paper and the printing quality evaluation of other paper.
基金support provided by the National Natural Science Foundation of China[Grant No.51802259]China Postdoctoral Science Foundation Funded Project[Grant No.2019M663785]+4 种基金the Natural Science Foundation of Shaanxi[Grant No.2019JQ-510]the Natural Science Basic Research Plan in Shaanxi Province of China[Grant No.2018JM5053],Xi’an and Xi’an Beilin District Programs for Science and Technology Plan[Grant No.201805037YD15CG21(18)and GX1913]the Promotion Program for Youth of Shaanxi University science and technology association[Grant No.20190415]Fund of Key laboratory of Processing and Quality Evaluation Technology of Green Plastics of China National Light Industry council[Grant No.PQETGP2019003]the Ph.D.Start-up fund project[Grant No.108-451118001]of Xi’an University of Technology.
文摘Cellulose plays a key role in abundant organic natural materials meeting the increasing demand for green and biocompatible products.The highly crystalline nanoscale component of cellulose nanocrystals has recently attracted great attention due to the versatile performance as filler or matrix in producing functional materials.In this work,we prepared the waterborne polyurethane via a prepolymer process,and obtained cellulose and cellulose nanocrystals from waste paper via a facile acid hydrolysis process.After that,the cellulose nanocrystals were assembled into film and mixed with polyurethane to prepare flexible polyurethane/cellulose nanocrystals composite membrane with different soaking time.The correlation between the bulk structure and applied properties including thermal resistance and mechanical property was investigated by using Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),differential scanning calorimetry(DSC)and folding test.The structure analysis indicates that cellulose nanocrystals prepared from used paper have a quality similar to that of commercial cellulose.Meanwhile,the cellulose nanocrystals have been mixed with polyurethane uniformly.Polyurethane can significantly benefit to the thermal resistance and mechanical property of the cellulose nanocrystals film.The polyurethane/cellulose nanocrystals composite membrane present good flexibility and may hold a significantly potential application as visual and flexible material.
基金The authors would like to gratefully acknowledge the financial support of National Natural Science Foundation of China(Grant No.51305345)Natural Science Basic Research Plan in Shaanxi Province of China(Grant No.2014JQ6228).
文摘Liquid-solid extrusion directly following vacuum infiltration(LSEVI)is an infiltration-extrusion integrated forming technique,and transverse weld between upper residual magnesium alloy and magnesium matrix composites is a common internal defect,which can severely reduce the yield of composite products.To improve current understanding on the mechanism of transverse welding phenomenon,a thermo-mechanical numerical model of LSEVI for magnesium matrix composites was developed.The formation of transverse weld during extrusion was visualized using finite element simulation method,and the formation mechanism was discussed from the aspect of velocity field using a point tracking technique.The simulation results were verified by the experimental results in term of weld shape.
基金Funded in part by the National Natural Science Foundation of China(Nos.51172180 and 51372200)the Program for New Century Excellent Talents in University of Ministry of Education of China(No.NCET-12-1045)+1 种基金the Local Service Program of Shaanxi Provincial Education Department(No.2013JC19)the Excellent Ph D Dissertation Foundation of XAUT(102-211208)
文摘Waste packaging polyethylene(WPE) was used to modify raw asphalt by melt blending the components at 190 ℃ for 1 h in a simple mixer and subsequently machining them at 120 ℃ for 1 h in a highspeed shearing machine.The effect of modification on the degree of the penetration,the softening point and the ductility of the asphalt was studied using fluorescent microscopy,infrared spectrometry,component changes and various other techniques.The experimental results showed that no chemical reactions took place in the components themselves(saturate,aromatic,asphaltene and resin) during the modifications.The softening point and penetration of the asphalt were found to be closely related to the resulting contents of the asphaltene,saturate and resin components.In addition,aromatics were identified as having the greatest impact on the ductility of the asphalt.
基金The author acknowledges the financial support provided by the National Natural Science Foundation of China[Grant No.51802259]China Postdoctoral Science Foundation Funded Project[Grant No.2019M663785]+6 种基金the Opening Project of Shanxi Key Laboratory of Advanced Manufacturing Technology[Grant No.XJZZ202001]the Scientific Research Project of Shaanxi Education Department[Grant No.20JS108]the Promotion Program for Youth of Shaanxi University science and technology association[Grant No.20190415]Fund of Key Laboratory of Processing and Quality Evaluation Technology of Green Plastics of China National Light Industry council[Grant No.PQETGP2019003]the Innovation Guidance of Technology Program of Shaanxi Province[Grant No.2020CGXNG-022]Xi’an Programs for Science and Technology Plan[Grant No.2020KJRC0090]The author also acknowledges the previous work[https://www.sciencedirect.com/science/article/pii/S030094401630323X].
文摘A facile method,focusing on emulsification,chain extension and dispersion process in preparing waterborne polyurethane,was developed to prepare emulsion with rod-like nanoparticles.The facile method involves a water addition procedure by in situ generated water to react with polyurethane prepolymer instead of the external water addition process.As a comparison,waterborne polyurethane was synthesized through the external water addition process.According to the characterization methods including FTIR,1H-NMR,TEM and water swelling experiments,it is suggested there are two kinds of hydrogen bonds interactions in hard/soft domain of the novel polyurethane,and the phase separation of hard/soft domains increases significantly.The morphology of the two polyurethanes was quite different(nanorods and spherical particles,respectively),presenting a different surface property.In addition,the water swelling of the novel polyurethane indicates that it holds significant potential application as degradable material.
基金The authors acknowledge the financial support provided by the Key R&D Program of Shaanxi Province(No.2022SF-168)Xi’an Programs for Science and Technology Plan(Nos.2020KJRC0090 and 21XJZZ0045)+5 种基金Xi’an Beilin District Programs for Science and Technology Plan(No.GX2247)the Outstanding Chinese and Foreign Youth Exchange Program of China Association for Science and Technology(CAST)in 2019the Opening Project of Shanxi Key Laboratory of Advanced Manufacturing Technology(No.XJZZ202001)the Scientific Research Project of Shaanxi Education Department(No.20JS108)Open Foundation of Key Laboratory of Auxiliary Chemistry and Technology for Chemical Industry,Ministry of Education,Shaanxi University of Science and Technology(No.KFKT2021-01)Shaanxi Collaborative Innovation Center of Industrial Auxiliary Chemistry and Technology,Shaanxi University of Science and Technology(No.KFKT2021-01).
文摘Greenhouse gas emissions from waste plastics have caused global warming all over the world,which has been a central threat to the ecological environment for humans,flora and fauna.Among waste plastics,waste polyethylene terephthalate(PET)is attractive due to its excellent stability and degradation-resistant.Therefore,merging China’s carbon peak and carbon neutrality goals would be beneficial.In this review,we summarize the current state-of-the-art of carbon emission decrease from a multi-scale perspective technologically.We suggest that the carbon peak for waste PET can be achieved by employing the closed-loop supply chain,including recycling,biomass utilization,carbon capture and utilization.Waste PET can be a valuable and renewable resource in the whole life cycle.Undoubtedly,all kinds of PET plastics can be ultimately converted into CO_(2),which can also be feedstock for various kinds of chemical products,including ethyl alcohol,formic acid,soda ash,PU,starch and so on.As a result,the closed-loop supply chain can help the PET plastics industry drastically reduce its carbon footprint.
基金"13115"Sci-Tech Innovation Programof Shaanxi Province,China(No.2008ZDKG39)Youth Foundation of Xi'an University of Technology,China(No.104210807)
文摘A method of restoring scratches on old paintings is proposed,and the corresponding high-accuracy output workflow is also developed.Firstly the scanner is selected as an input device to get the RGB(red,green,blue)image of the painting,and for the purpose of capturing high-quality image,scanner characterization is done by using neural network.And then the scratches on the RGB image are restored with the technology of digital inpainting,while the inpainting algorithm is mainly based on gradient vector and fast marching method.Finally the restored image is output with a printer,which is calibrated by using the high order polynomial regression method.In experiment the new replicated painting is well restored in the scratched areas,as well as keeps high resemblance with the original painting.
基金the NSFC Funds under Grant 52075440National Key Research and Development Program of China(No.2021YFD1600402)+2 种基金Central Guidance on Local Science and Technology Development Fund of Shaanxi Province(No.2020-ZYYD-NCC-9)Shaanxi Provincial Department of Education Collaborative Innovation Center Project(20JY052)National Natural Science Foundation of China(No.52072075)。
文摘Flexible sensors are attractive due to potential applications in body exercise and ambient gas monitoring systems.Cellulose and its derivatives have combined superiorities such as intrinsic and structural flexibility,ease of chemical functionalization,moisture sensitivity,and mechanical stability,enabling them to be promising candidates as flexible supporting substrates and flexible sensitive materials.Significant progress consequently has been achieved to improve mechanical,electrical,and chemical performance.The latest advance in materials synthesis,structure design,fabrication control,and working mechanism of novel cellulose-based flexible sensors are reviewed and discussed,including strain sensors,humidity sensors,and harmful gas sensors.Various strategies were summarized to enhance sensor performance by surface group modifications,inorganic and organic conducting fillers optimization,multilayer structure design.Newly emerged processing techniques of self-assembly,vacuum filtration,and 3D printing were introduced as well to construct multiscale microstructures.The integration of multiple sensors toward smart and healthy exercise monitoring system is briefly reviewed.The facing challenges and future opportunities of cellulose-based flexible sensors were discussed and proposed at the end.This review provides inspiration and guidelines on how to design and fabricate cellulose-based flexible sensors.
基金supported by ISF-SFC joint research program(No.51961145305)Key Research and Development Program of Shaanxi Province(No.2021KWZ-12)+1 种基金Doctoral Dissertation Innovation Fund of Xi’an University of Technology(No.252072103)the Youth Innovation Team of Shaanxi Universities contributed equally to this work.
文摘Dielectric polymer film capacitors with a high-power density as well as efficient charge and discharge rates have great potential for application to fulfill the miniaturized and lightweight requirements of the electronic and stationary power systems.It was reported that the elastic recovery rate and energy storage density of poly(vinylidene fluoride-chlorotrifluoroethylene)[P(VDF-CTFE)]polymer film can be enhanced through thermostatic uniaxial stretching.But it is unknown about the relationship between the stretching rate and above properties.In this study,we investigated the effect of different stretching rates on the conformation,elastic recovery,dielectric constant,and energy storage density of stretched P(VDF-CTFE)polymer films.It was found that the stretching rate significantly affected the formation of polarβ-crystal phase,causing different dielectric properties.The degrees of elastic recovery of P(VDF-CTFE)film vary with stretching rates.Among them,the elastic recovery rate of the P(VDF-CTFE)94/6 film is 46.5%at a stretching rate of 15 mm/min,the dielectric constant is 12.25 at 100 Hz,and the energy density reaches 3.95 J/cm^(3) with the energy loss of 39%at 200 MV/m field.
基金supported by the National Natural Science Foundation of China (NSFC) (Nos.62061136009 and 51877031)the High-level Talents Plan of Shaanxi Province,the“Belt and Road Initiative”Overseas Expertise Introduction Center for Smart Energy and Reliability of Transmission and Distribution Equipment of Shaanxi Province,the State Key Laboratory of Engineering Dielectrics and Its Applications (Ministry of Education,China)+2 种基金the State Key Laboratory of Reliability and Intelligence Electrical Equipment (Hebei University of Technology,China,No.EERIKF2018010)Key R&D Program of Shaanxi Province (No.2022SF-168)Xi’an Programs for Science and Technology Plan (No.21XJZZ0045).
文摘The insulation degradation in polymeric backsheets has been identified as a main cause of catastrophic accidents induced by short circuit or ground faults in photovoltaic module.To ensure quality,the photovoltaic industry is therefore faced with urgent demand in discovering degradation mechanisms.Moreover,the development of environmental-friendly backsheets and the establishment of backsheets recycling specifications are vital to fulfilling the requirements of a future reliable photovoltaic system with improved productivity.In this review,we innovatively summarize the detection methods of insulation deterioration from the viewpoints of spectroscopic,thermal and mechanical approaches.The corresponding ambient conditions in measurement and their accelerating effect on the degradation of photovoltaic backsheets are discussed.Subsequently,emerging novel materials and structures for enhancing insula-tion properties,antiaging performance and optical-electrical energy conversion efficiency of photovoltaic cell are summarized.It offers a comprehensive strategy to design materials with optimal structures in photovoltaic module for a future zero-carbon energy system.
基金supported by the National Natural Science Foundation of China(22374119,22274127,61901389)the Research Fund of the State Key Laboratory of Solidification Processing(NPU),China(2021-QZ-01)the Key Project of the Natural Science Fund of Shaanxi Province(2023-JC-ZD-06).
文摘It is important to monitor the intra-/extracellular concentration of hydrogen peroxide(H_(2)O_(2))in biological processes.However,miniaturized devices that enable portable and accurate H_(2)O_(2)measurement are still in their infancy because of the difficulty of developing facile sensing strategies and highly integrated sensing devices.In this work,portable H_(2)O_(2)sensors based on Pt-Ni hydrogels with excellent peroxidase-like and electrocatalytic activities are demonstrated.Thus,simple and sensitive H_(2)O_(2)sensing is achieved through both colorimetric and electrochemical strategies.The as-fabricated H_(2)O_(2)sensing chips exhibit favorable performance,with low detection limits(0.030μM&0.15μM),wide linearity ranges(0.10μM-10.0 mM&0.50μM-5.0 mM),outstanding long-term stability(up to 60 days),and excellent selectivity.With the aid of an M5stack development board,portable visual and electrochemical H_(2)O_(2)sensors are successfully constructed without complicated and expensive equipment or professional operators.When applied to the detection of H_(2)O_(2)released from HeLa cells,the results obtained by the developed sensors are in good agreement with those from an ultraviolet‒visible spectrophotometer(UV‒vis)(1.97μM vs.2.08μM)and electrochemical station(1.77μM vs.1.84μM).
基金the National Natural Science Foundation of China(Grant Nos.51372200 and 51772243)the Foundation of the State Key Laboratory of Solidification Processing in NWPU(Grant No.SKLSP201753)+2 种基金Scientific Research Plan Projects of Shaanxi Education Department(Grant No.16JK1551)Technology Innovation Programme of Xi’an University of Technology(Grant No.2016CX030)China Postdoctoral Science Foundation(Grant No.2016M592824)
文摘Thermochromic material is a kind of smart material whose color will vary as the result of the phase transition caused by the temperature change. The characteristics of thermochromic materials are the memory functions to the temperature, having great potential applications in aerospace, military, anticounterfeiting technology, construction and other fields. In recent years, many kinds of thermochromic materials have been prepared by different methods and their discoloration mechanisms are various according to published literatures. In this paper, the classification, discoloration mechanism, preparation methods, application fields and development trend of thermochromic materials are reviewed.
基金supported by the fund of the Beijing Laboratory for Food Quality and Safety, Beijing Technology and Business University (Grant No. FQS-201709)China Postdoctoral Science Foundation Funded Project (Grant No. 2016M592824)+1 种基金the Science and Technology Plan of Yulin City (Grant No. 2016-16-7)the Science and Technology Plan of Beilin District (Grant No. GX1710)
文摘A synthesis strategy of fluorescent carbon quantum dots(CQDs) with high quantum yield(QY) using aqua mesophase pitch(AMP) as the carbon source has been developed via the hydrothermal method in this study. The hydrothermal temperature and soaking time have important effects on the morphology and QY of CQDs. As-prepared CQDs at 120℃ holding for 24 h(CQDs-120-24) have the uniform size of about 2.8 nm, and the QY can reach 27.6%. The obtained CQDs are successfully modified with ammonia and thionyl chloride, respectively, and they exhibit an excellent photocatalytic performance on degrading rhodamine B(Rh B), methyl blue(MB) and indigo carmine(IC). Importantly, the degradation percentage of N-CQDs on Rh B under natural light for 4 h reaches 97% with the degradation rate constant of 0.02463 min^(-1) and it can maintain 93% after repetitively used 5 times. The results indicate that these as-prepared CQDs have the potential application in degrading organic dyes.
基金?nancial support provided by Program for New Century Excellent Talents in University by the Ministry of Education of China(Grant No.NCET-12-1045)the Shaanxi Programs for Science and Technology Development(No.2010K01-096)Ph.D.Innovation Fund Projects of Xi’an University of Technology(No.310-252071501)
文摘Anionomer-type waterborne polyurethane dispersions(PUDs) were obtained from poly(propylene glycol)(PPG), isophorone diisocyanate(IPDI) and dimethylolpropionic acid(DMPA) through a modi?ed prepolymer isocyanate process. Two series of polyurethanes were prepared(Groups A and B) and a new prediction model based on grey relational analysis is introduced to predict the impact order of raw materials on several properties, such as solids content, viscosity, acid number and electrolytic stability of polyurethanes. It is found that the model can successfully predict the impact of raw materials on the properties through the designed demonstration experiments. Furthermore, the results of the prediction model show that DMPA plays a key role in viscosity, partial acid values and electrolytic stability.
基金co-supported by the Fundamental Research Funds for the Central Universities of China,China Postdoctoral Science Foundation(No.2018M631196)the National Natural Foundation of China(No.51705420).
文摘Multi-faults detection is a challenge for rolling bearings due to the mode mixture and coupling of multiple fault features,as well as its easy burying in the complex,non-stationary structural vibrations and strong background noises.In this paper,a method based on the flexible analytical wavelet transform(FAWT)possessing fractional scaling and translation factors is proposed to identify multiple faults occurred in different components of rolling bearings.During the route of the proposed method,the proper FAWT bases are constructed via genetic optimization algorithm(GA)based on maximizing the spectral correlated kurtosis(SCK)which is firstly presented and proved to be efficient and effective in indicating interested fault mode.Via using the customized FAWT bases for each interested fault mode,the original vibration measurements are decomposed into fine frequency subbands,and the sensitive subband which enhances the signal-to-noise ratio(SNR)is selected to exhibit the fault signature on its envelope spectrum.The proposed method is tested via simulated signals,and applied to analyze the experimental vibration measurements from the running roller bearings subjected to outrace,inner-race and roller defects.The analysis results validate the effectiveness of the proposed method in identifying multi-faults occurred in different components of rolling bearings.
