SnO2‐supported Pd catalysts were prepared and the effects of the support calcination temperature on the subsequent catalytic activity during methane combustion were investigated.The physicochemical properties of the ...SnO2‐supported Pd catalysts were prepared and the effects of the support calcination temperature on the subsequent catalytic activity during methane combustion were investigated.The physicochemical properties of the Pd/SnO2were characterized by X‐ray diffraction,high‐resolution transmission electron microscopy,X‐ray photoelectron spectroscopy,oxygen temperature‐programmed desorption and CH4temperature‐programmed surface reaction.Only crystalline Pd species were found on the catalysts fabricated from the supports calcined above800°C.It was also determined that lattice geometry matching between PdO and SnO2in the catalyst made with a support calcined at1200°C facilitated oxygen activation from SnO2to vacant oxygen sites on the PdO/Pd surface via the back‐spillover of oxygen.This effect in turn enhanced the catalytic combustion process.The activity of this material was clearly increased compared with the catalysts that did not exhibit lattice matching between the PdO and support.展开更多
With increasing design demands of turbomachinery,stochastic flutter behavior has become more prominent and even appears a hazard to reliability and safety.Stochastic flutter assessment is an effective measure to quant...With increasing design demands of turbomachinery,stochastic flutter behavior has become more prominent and even appears a hazard to reliability and safety.Stochastic flutter assessment is an effective measure to quantify the failure risk and improve aeroelastic stability.However,for complex turbomachinery with multiple dynamic influencing factors(i.e.,aeroengine compressor with time-variant loads),the stochastic flutter assessment is hard to be achieved effectively,since large deviations and inefficient computing will be incurred no matter considering influencing factors at a certain instant or the whole time domain.To improve the assessing efficiency and accuracy of stochastic flutter behavior,a dynamic meta-modeling approach(termed BA-DWTR)is presented with the integration of bat algorithm(BA)and dynamic wavelet tube regression(DWTR).The stochastic flutter assessment of a typical compressor blade is considered as one case to evaluate the proposed approach with respect to condition variabilities and load fluctuations.The evaluation results reveal that the compressor blade has 0.95% probability to induce flutter failure when operating 100% rotative rate at t=170 s.The total temperature at rotor inlet and dynamic operating loads(vibrating frequency and rotative rate)are the primary sensitive parameters on flutter failure probability.Bymethod comparisons,the presented approach is validated to possess high-accuracy and highefficiency in assessing the stochastic flutter behavior for turbomachinery.展开更多
For fragile products,packaging requires cushioning protection to prevent irreversible damage from accidental falls,transportation impacts,and other causes.The new polyurethane foam(PUF)material demonstrates superior c...For fragile products,packaging requires cushioning protection to prevent irreversible damage from accidental falls,transportation impacts,and other causes.The new polyurethane foam(PUF)material demonstrates superior cushioning and vibration isolation performance in practical applications,effectively minimizing damage from vibrations.Drop and vibration experiments were conducted on packages comprising novel PUF,expandable polyethylene,ethylene-vinyl acetate copolymer foam,and bracelets.Results verify that the new PUF material outperforms in cushioning and vibration isolation,as observed from the acceleration response.Furthermore,a random vibration analysis of a packaging unit involving different thicknesses of PUF materials and bracelets reveals the enhanced vibration isolation effect within a specific thickness range.The vibration results of the bracelet’s outer packaging align closely with finite element simulation results,validating the effectiveness of designing and optimizing the outer packaging.Through finite element simulation,deeper understanding and prediction of the bracelet’s vibration response under various conditions is achieved,facilitating optimized packaging design for better protection and vibration damping.展开更多
A multi-responsive D-A type compound(CYQ)based on pyrone and triphenylamine was designed and successfully synthesized. The target compound exhibited distinct aggregation-enhanced emission(AEE) effect.Solvatochromic ex...A multi-responsive D-A type compound(CYQ)based on pyrone and triphenylamine was designed and successfully synthesized. The target compound exhibited distinct aggregation-enhanced emission(AEE) effect.Solvatochromic experiment and density functional theory(DFT) indicated CYQ possessed excellent intramolecular charge transfer(ICT) ability. Besides, its mechanofluorochromic property(MFC) was found with a 37 nm redshift. Powder wide-angle X-ray diffraction(PXRD) and differential scanning calorimetry(DSC) measurements were performed to demonstrate the transformation from the crystalline to amorphous states upon grinding. Surprisingly,CYQ displayed a hypersensitive response to trace water in organic solvents with an excellent detection limit as low as 0.0096% in tetrahydrofuran(THF). Furthermore, it was found that the fluorescent intensity of CYQ declined progressively upon humidity rise, and its color change can be witnessed by naked eyes. Therefore, the relative humidity(RH) sensing strategy guarantees the AIEgen to become a colorimetric sensor under various conditions.展开更多
The favorable antioxidant and antimicrobial activities of lignin have been shown to promote wound healing.However,the accumulation of lignin in high concentrations in the body brings about varying degrees of biotoxici...The favorable antioxidant and antimicrobial activities of lignin have been shown to promote wound healing.However,the accumulation of lignin in high concentrations in the body brings about varying degrees of biotoxicity.Herein,a controlled/sustained release polyvinyl alco-hol/chitosan/sulfonated lignin hydrogel(PVA-CS-L)integrated mechanical strengthening and bioactivities of lignin was developed.The lignin-induced non-covalent bond network(van der Waals force,hydrogen and electrostatic interactions)promoted energy dissipation when the hy-drogel was subjected to stretching and compression.This endowed the PVA-CS-L hydrogel with improved tensile(∼36 kPa)and compressive strength(∼900 kPa),as well as compressive tough-ness(∼9.0 MJ/m^(3)),which were superior to the polyvinyl alcohol/chitosan hydrogel(PVA-CS)(31 kPa,680 kPa,and 7.5 MJ/m^(3),respectively).The construction of electrostatic interaction could not only slow down the sudden release of lignin but also make the hydrogel exhibit a good pH-sensitive behavior of controlled-release lignin.Also,the developed hydrogel had good biocom-patibility and the released lignin had reactive oxygen species scavenging as well as inhibitory activity against Staphylococcus aureus.Finally,preliminary evaluation of drug delivery reveals that the presence of lignin enabled the hydrogel to exhibit longer-lasting controlled/sustained epigallocatechin gallate release properties.Such lignin-based controlled/sustained release hydro-gel that integrates the molecular structure and biological difunctional features of lignin gives new insight into cost-effective,easy-to-operate manufacturing of load-bearing and bioactive materials.展开更多
基金supported by the National High Technology Research and Development Program of China (2015AA034603)the National Key Research and Development Program of China (2016YFC0204300)+2 种基金the National Natural Science Foundation of China (21171055,21333003,21571061)the "Shu Guang" Project of the Shanghai Municipal Education Commission (12SG29)the Commission of Science and Technology of Shanghai Municipality (15DZ1205305)~~
文摘SnO2‐supported Pd catalysts were prepared and the effects of the support calcination temperature on the subsequent catalytic activity during methane combustion were investigated.The physicochemical properties of the Pd/SnO2were characterized by X‐ray diffraction,high‐resolution transmission electron microscopy,X‐ray photoelectron spectroscopy,oxygen temperature‐programmed desorption and CH4temperature‐programmed surface reaction.Only crystalline Pd species were found on the catalysts fabricated from the supports calcined above800°C.It was also determined that lattice geometry matching between PdO and SnO2in the catalyst made with a support calcined at1200°C facilitated oxygen activation from SnO2to vacant oxygen sites on the PdO/Pd surface via the back‐spillover of oxygen.This effect in turn enhanced the catalytic combustion process.The activity of this material was clearly increased compared with the catalysts that did not exhibit lattice matching between the PdO and support.
基金co-supported by the National Natural Science Foundation of China(Grants 51975028 and 52105136)China Postdoctoral Science Foundation(Grant 2021M690290)the National Science and TechnologyMajor Project(Grant J2019-Ⅳ-0016-0084).
文摘With increasing design demands of turbomachinery,stochastic flutter behavior has become more prominent and even appears a hazard to reliability and safety.Stochastic flutter assessment is an effective measure to quantify the failure risk and improve aeroelastic stability.However,for complex turbomachinery with multiple dynamic influencing factors(i.e.,aeroengine compressor with time-variant loads),the stochastic flutter assessment is hard to be achieved effectively,since large deviations and inefficient computing will be incurred no matter considering influencing factors at a certain instant or the whole time domain.To improve the assessing efficiency and accuracy of stochastic flutter behavior,a dynamic meta-modeling approach(termed BA-DWTR)is presented with the integration of bat algorithm(BA)and dynamic wavelet tube regression(DWTR).The stochastic flutter assessment of a typical compressor blade is considered as one case to evaluate the proposed approach with respect to condition variabilities and load fluctuations.The evaluation results reveal that the compressor blade has 0.95% probability to induce flutter failure when operating 100% rotative rate at t=170 s.The total temperature at rotor inlet and dynamic operating loads(vibrating frequency and rotative rate)are the primary sensitive parameters on flutter failure probability.Bymethod comparisons,the presented approach is validated to possess high-accuracy and highefficiency in assessing the stochastic flutter behavior for turbomachinery.
基金the National Natural Science Foundation of China(Grant Numbers 12172151 and 12172149).
文摘For fragile products,packaging requires cushioning protection to prevent irreversible damage from accidental falls,transportation impacts,and other causes.The new polyurethane foam(PUF)material demonstrates superior cushioning and vibration isolation performance in practical applications,effectively minimizing damage from vibrations.Drop and vibration experiments were conducted on packages comprising novel PUF,expandable polyethylene,ethylene-vinyl acetate copolymer foam,and bracelets.Results verify that the new PUF material outperforms in cushioning and vibration isolation,as observed from the acceleration response.Furthermore,a random vibration analysis of a packaging unit involving different thicknesses of PUF materials and bracelets reveals the enhanced vibration isolation effect within a specific thickness range.The vibration results of the bracelet’s outer packaging align closely with finite element simulation results,validating the effectiveness of designing and optimizing the outer packaging.Through finite element simulation,deeper understanding and prediction of the bracelet’s vibration response under various conditions is achieved,facilitating optimized packaging design for better protection and vibration damping.
基金financial support from the National Natural Science Foundation of China (21576194)
文摘A multi-responsive D-A type compound(CYQ)based on pyrone and triphenylamine was designed and successfully synthesized. The target compound exhibited distinct aggregation-enhanced emission(AEE) effect.Solvatochromic experiment and density functional theory(DFT) indicated CYQ possessed excellent intramolecular charge transfer(ICT) ability. Besides, its mechanofluorochromic property(MFC) was found with a 37 nm redshift. Powder wide-angle X-ray diffraction(PXRD) and differential scanning calorimetry(DSC) measurements were performed to demonstrate the transformation from the crystalline to amorphous states upon grinding. Surprisingly,CYQ displayed a hypersensitive response to trace water in organic solvents with an excellent detection limit as low as 0.0096% in tetrahydrofuran(THF). Furthermore, it was found that the fluorescent intensity of CYQ declined progressively upon humidity rise, and its color change can be witnessed by naked eyes. Therefore, the relative humidity(RH) sensing strategy guarantees the AIEgen to become a colorimetric sensor under various conditions.
基金financial support from National Natural Science Foundation of China(No.32201500No.32271811)+2 种基金Natural Science Foundation of Jiangsu Province(No.BK20220431)Jiangsu Provincial Key Research and Development Program(No.BE2021368)the China Postdoctoral Science Foundation(No.2023M731708).
文摘The favorable antioxidant and antimicrobial activities of lignin have been shown to promote wound healing.However,the accumulation of lignin in high concentrations in the body brings about varying degrees of biotoxicity.Herein,a controlled/sustained release polyvinyl alco-hol/chitosan/sulfonated lignin hydrogel(PVA-CS-L)integrated mechanical strengthening and bioactivities of lignin was developed.The lignin-induced non-covalent bond network(van der Waals force,hydrogen and electrostatic interactions)promoted energy dissipation when the hy-drogel was subjected to stretching and compression.This endowed the PVA-CS-L hydrogel with improved tensile(∼36 kPa)and compressive strength(∼900 kPa),as well as compressive tough-ness(∼9.0 MJ/m^(3)),which were superior to the polyvinyl alcohol/chitosan hydrogel(PVA-CS)(31 kPa,680 kPa,and 7.5 MJ/m^(3),respectively).The construction of electrostatic interaction could not only slow down the sudden release of lignin but also make the hydrogel exhibit a good pH-sensitive behavior of controlled-release lignin.Also,the developed hydrogel had good biocom-patibility and the released lignin had reactive oxygen species scavenging as well as inhibitory activity against Staphylococcus aureus.Finally,preliminary evaluation of drug delivery reveals that the presence of lignin enabled the hydrogel to exhibit longer-lasting controlled/sustained epigallocatechin gallate release properties.Such lignin-based controlled/sustained release hydro-gel that integrates the molecular structure and biological difunctional features of lignin gives new insight into cost-effective,easy-to-operate manufacturing of load-bearing and bioactive materials.
