To figure out the load distribution of thin-section rolling bearing supported by flexible structure with squirrel cage and the distribution's influence on bearing life,an iterative FEA method is proposed to use th...To figure out the load distribution of thin-section rolling bearing supported by flexible structure with squirrel cage and the distribution's influence on bearing life,an iterative FEA method is proposed to use the result calculated from the Quasi-Dynamic model based on the rigid support hypothesis. The contact angle,contact position and stiffness of equivalent spring are modified during the iterative FEA to optimize the FEA model,and then the bearings' life can be predicted when the error is below 0.5%. It can be concluded that from the analysis results the load distribution under flexible support is more uniform than that of the rigid support,while the maximum load decreases by 11.2% and bearing life increases by 14.7%. The analysis result of different values of thickness of bearing house,rings and hollow shaft demonstrates the thicknesses of bearing house and hollow shaft have a greater influence on the load's uniformity and bearing's life than those of the rings.展开更多
The objective of this study is to investigate the spatiotemporal dynamics of a Rhizophagusgrandis-Dendroctonusvalenspredator-prey system.Under Neu-mann boundary conditions,we establish a reaction-diffusion system inco...The objective of this study is to investigate the spatiotemporal dynamics of a Rhizophagusgrandis-Dendroctonusvalenspredator-prey system.Under Neu-mann boundary conditions,we establish a reaction-diffusion system incorpo-rating Holling-II functional response,nonlocal effect,predator-prey taxis and time delay to elucidate the regulatory mechanisms of chemotactic behaviors and delayed predation pressure on ecosystem stability.In addition,we inves-tigate the existence conditions for Hopf bifurcation and employ the multiple time scales method to derive its normal form.Under appropriate parameter constraints,numerical simulations demonstrate that the system exclusively exhibits Hopf bifurcation in the current parameter configuration,where non-local interactions,taxis and time delays synergistically induce the formation of spatially heterogeneous periodic solutions.These results elucidate the in-trinsic mechanism underlying periodic pest outbreaks and provide a theoret-ical foundation for optimizing biological control strategies.Notably,our anal-ysis reveals the critical role of predator taxis capability and delayed predation feedback in stabilizing pest population cycles,offering practical guidance for sustainable forest pest management.展开更多
Pine wilt disease is a destructive forest disease with strong infectivity,a wide spread range and high difficulty in prevention and control.Since controlling Monochamus alternatus,the vector of pine wood nematode(Burs...Pine wilt disease is a destructive forest disease with strong infectivity,a wide spread range and high difficulty in prevention and control.Since controlling Monochamus alternatus,the vector of pine wood nematode(Bursaphelenchus rylophilus)can reduce the occurrence of pine wilt disease efficiently,the parasitic natural enemy of M.alternatus,Dastarcus helophoroides,is introduced in this paper.Considering the infuence of parasitic time of D.helophoroides on the control effect,based on the mutualistic symbiosis and parasitic relationship among pine wood nematode,M.alternatus and D.heloporoides,this paper establishes a pine wood nematode prevention and control model with delay.Then,the stability of positive equilibrium and the existence of Hopf bifurcation are discussed.Besides,we obtain the normal form of Hopf bifurcation by applying the multiple time scales method.Finally,numerical simulations with two sets of meaningful parameters selected by means of statistical analysis are carried out to support the theoretical findings.Through the comparative analysis of numerical simulations,the factors affecting the control effect of pine wilt disease are obtained,and some suggestions are put forward for practical control in the forest.展开更多
Yeast-driven alcoholic fermentation is widely applied to process fruits into value-added beverages.Fruit geno-types,yeast strains,and beverage production methods significantly influence the diversity and quality of al...Yeast-driven alcoholic fermentation is widely applied to process fruits into value-added beverages.Fruit geno-types,yeast strains,and beverage production methods significantly influence the diversity and quality of alco-holic beverages.Traditionally,Saccharomyces cerevisiae is regarded as the most commercially important yeast in the alcoholic beverage production markets,whereas other Saccharomyces and non-Saccharomyces is considered to be either harmful or useless.However,the interest of applying these yeasts in numerous innovative yeast fer-mented alcoholic fruit-based beverages is growing due to their advantageous flavor attributions.In this review,the strategies for enhancing volatile properties and aroma and flavor complexity of alcoholic beverage fermentation were critically examined with a special emphasis on fruit types and yeast strains,as well as their impacts on the quality of alcoholic beverages.The current challenges and future prospects were also discussed on the development of desirable alcoholic beverage production.展开更多
Co-fermentation technology is expected to improve the flavor and quality properties of fermented surimi products.Effects of fermentation with Monascus purpureus(M.purpureus)and Actinomucor elegans(A.elegans)at differe...Co-fermentation technology is expected to improve the flavor and quality properties of fermented surimi products.Effects of fermentation with Monascus purpureus(M.purpureus)and Actinomucor elegans(A.elegans)at different inoculation ratios on the volatile profiles and physicochemical properties of surimi were investigated.Generally,fermentation resulted in significant surimi protein hydrolysis as indicated by increased amino acid nitrogen,TCA-soluble peptide and free amino acid contents,simultaneously accompanied by decreases in hardness,gumminess and chewiness of surimi.Co-fermentation effectively improved the volatile profiles of surimi.Comparatively,a higher inoculation ratio of M.purpureus was favorable for the production of esters and ketones,whereas a higher proportion of A.elegans reduced the aldehyde contents,especially nonanal with fishy odor.Taken together,a 1:1 inoculation ratio of M.purpureus and A.elegans was more conductive to improve the aroma profiles of surimi,with a 77.2%reduction of aldehyde compared to unfermented surimi.展开更多
This study aimed to better understand the changes of fatty acids in dry-cured fish during storage,and to analyze the reactive carbonyl species(RCS)formation mechanism primarily from the standpoint of oxygen-derived fr...This study aimed to better understand the changes of fatty acids in dry-cured fish during storage,and to analyze the reactive carbonyl species(RCS)formation mechanism primarily from the standpoint of oxygen-derived free radical reactions interactions.Oleic acid and linoleic acid were the predominant unsaturated fatty acids in dry-cured fish.The content of unsaturated fatty acids in dry-cured fish increased over time at 4℃,while decreased at 25℃.Singlet oxygen,superoxide anion and hydroxyl-alkyl radical levels increased with time,and more free radicals were yielded in the samples held at 25℃.Redundancy analysis revealed that hydroxyl-alkyl radicals had the greatest influence on the oxidation of lipids.Hydroxyl-alkyl radicals and singlet oxygen levels were positively correlated with 4-hydroxy-2-nonenal(HNE),malondialdehyde(MDA),peroxide value and acid value levels,but adversely to 4-hydroxy-2-hexenal(HHE)and fatty acids levels.Moreover,HNE and MDA were both inversely linked with fatty acids contents.It is possible that the intermediates of lipid oxidation undergo oxidation,cleavage and other reactions due to free radical activity,resulting in the generation of aldehyde precursors.These findings help us further characterize the lipid oxidation and RCS formation mechanism in dry-cured fish during storage.展开更多
The effect of cryoprotectants on the changes of physicochemical and structural properties of egg white protein(EWP)caused by repeated freeze-thaw(F-T)cycles was investigated.The cryoprotectants(4%trehalose+0.3%carrage...The effect of cryoprotectants on the changes of physicochemical and structural properties of egg white protein(EWP)caused by repeated freeze-thaw(F-T)cycles was investigated.The cryoprotectants(4%trehalose+0.3%carrageenan,TC;1% xylo-oligosaccharide+0.3% carrageenan,XC;4% trehalose+1% xylo-oligosaccharide,TX)were added to the egg white,and stored at F-T for 1,3,and 5 cycles.The freezing protection effect of cryoprotectants on EWP was discussed by detecting carbonyl contents,total sulfhydryl group content,surface hydrophobicity,water-holding capacity(WHC)of heat-induced gel,SDS-PAGE and the secondary and tertiary structure of protein.The results showed that cryoprotectants could effectively inhibit the increase in surface hydrophobicity and carbonyl contents,and restrict the decrease in total sulfhydryl group content,WHC of heat-induced gel and endogenous fluorescence intensity(p<0.05).The results can provide reference for the application of cryoprotectants in frozen EWP using in food industry.展开更多
In this investigation,the impacts of malondialdehyde(MDA),4-hydroxy-2-nonena(HNE),and their combinations on the structural characteristics of myofibrillar proteins(MP)were examined using endogenous fluorescence,Fourie...In this investigation,the impacts of malondialdehyde(MDA),4-hydroxy-2-nonena(HNE),and their combinations on the structural characteristics of myofibrillar proteins(MP)were examined using endogenous fluorescence,Fourier transform infrared spectrum(FTIR)and Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis(SDS-PAGE).The potential binding mechanisms were also explored using LC-MS/MS and proteomics techniques.The findings indicated that various reactive carbonyl compounds(RCCs)displayed distinct oxidation performances in the oxidation of myofibrillar proteins.Samples containing HNE(HMP and MHMP groups)exhibited a more pronounced ability to oxidize MP than those containing MDA,as evidenced by their higher carbonyl content and lower sulfhydryl content.The MHMP group demonstrated the greatest surface hydrophobicity and Schiff base content but the lowest fluorescence intensity,suggesting that MDA and HNE synergistically altered MP conformation.Moreover,the alteration by RCCs notably modified the secondary structure of MP.Among these,HMP triggered the unfolding of MP molecules,resulting in the lowest α-helix and highest β-sheet ratio.The SDS‒PAGE results suggested that MDA oxidation promoted the crosslinking of MP molecules.At the same time,HNE caused the degradation of MP,as indicated by the decrease in the intensity of the high-molecular-weight bands.Proteomic analysis suggested that lysine residues distributed in the tail region of myosin were the main binding sites for MDA,whereas HNE preferentially modified methionine located at the myosin head.Additionally,HNE-induced protein degradation dominated RCC-induced oxidation reactions.These findings provide deeper insights into the mechanisms underlying quality changes induced by lipid oxidation products in MP-based food systems.展开更多
基金Sponsored by the Major State Basic Research Development Program of China(Grant No.2013CB632305)the National Natural Science Foundation of China(Grant No.51375108)
文摘To figure out the load distribution of thin-section rolling bearing supported by flexible structure with squirrel cage and the distribution's influence on bearing life,an iterative FEA method is proposed to use the result calculated from the Quasi-Dynamic model based on the rigid support hypothesis. The contact angle,contact position and stiffness of equivalent spring are modified during the iterative FEA to optimize the FEA model,and then the bearings' life can be predicted when the error is below 0.5%. It can be concluded that from the analysis results the load distribution under flexible support is more uniform than that of the rigid support,while the maximum load decreases by 11.2% and bearing life increases by 14.7%. The analysis result of different values of thickness of bearing house,rings and hollow shaft demonstrates the thicknesses of bearing house and hollow shaft have a greater influence on the load's uniformity and bearing's life than those of the rings.
基金funded by the Heilongjiang Provincial Natural Science Foundation of China(Grant No.LH2024A001)the College Students Innovations Special Project funded by Northeast Forestry University(No.DCLXY-2025010).
文摘The objective of this study is to investigate the spatiotemporal dynamics of a Rhizophagusgrandis-Dendroctonusvalenspredator-prey system.Under Neu-mann boundary conditions,we establish a reaction-diffusion system incorpo-rating Holling-II functional response,nonlocal effect,predator-prey taxis and time delay to elucidate the regulatory mechanisms of chemotactic behaviors and delayed predation pressure on ecosystem stability.In addition,we inves-tigate the existence conditions for Hopf bifurcation and employ the multiple time scales method to derive its normal form.Under appropriate parameter constraints,numerical simulations demonstrate that the system exclusively exhibits Hopf bifurcation in the current parameter configuration,where non-local interactions,taxis and time delays synergistically induce the formation of spatially heterogeneous periodic solutions.These results elucidate the in-trinsic mechanism underlying periodic pest outbreaks and provide a theoret-ical foundation for optimizing biological control strategies.Notably,our anal-ysis reveals the critical role of predator taxis capability and delayed predation feedback in stabilizing pest population cycles,offering practical guidance for sustainable forest pest management.
基金funded by Fundamental Research Funds for the Central Universities of China(No.2572022DJ06).
文摘Pine wilt disease is a destructive forest disease with strong infectivity,a wide spread range and high difficulty in prevention and control.Since controlling Monochamus alternatus,the vector of pine wood nematode(Bursaphelenchus rylophilus)can reduce the occurrence of pine wilt disease efficiently,the parasitic natural enemy of M.alternatus,Dastarcus helophoroides,is introduced in this paper.Considering the infuence of parasitic time of D.helophoroides on the control effect,based on the mutualistic symbiosis and parasitic relationship among pine wood nematode,M.alternatus and D.heloporoides,this paper establishes a pine wood nematode prevention and control model with delay.Then,the stability of positive equilibrium and the existence of Hopf bifurcation are discussed.Besides,we obtain the normal form of Hopf bifurcation by applying the multiple time scales method.Finally,numerical simulations with two sets of meaningful parameters selected by means of statistical analysis are carried out to support the theoretical findings.Through the comparative analysis of numerical simulations,the factors affecting the control effect of pine wilt disease are obtained,and some suggestions are put forward for practical control in the forest.
基金the financial supports from First Division Alar City Financial Science and Technology Plan Project(No.2024SP01)National Natural Science Foundation of China(No.32402151).
文摘Yeast-driven alcoholic fermentation is widely applied to process fruits into value-added beverages.Fruit geno-types,yeast strains,and beverage production methods significantly influence the diversity and quality of alco-holic beverages.Traditionally,Saccharomyces cerevisiae is regarded as the most commercially important yeast in the alcoholic beverage production markets,whereas other Saccharomyces and non-Saccharomyces is considered to be either harmful or useless.However,the interest of applying these yeasts in numerous innovative yeast fer-mented alcoholic fruit-based beverages is growing due to their advantageous flavor attributions.In this review,the strategies for enhancing volatile properties and aroma and flavor complexity of alcoholic beverage fermentation were critically examined with a special emphasis on fruit types and yeast strains,as well as their impacts on the quality of alcoholic beverages.The current challenges and future prospects were also discussed on the development of desirable alcoholic beverage production.
基金supported by the National Key R&D Program of China(2023YFD2401502)National Natural Science Foundation of China(No.32402151).
文摘Co-fermentation technology is expected to improve the flavor and quality properties of fermented surimi products.Effects of fermentation with Monascus purpureus(M.purpureus)and Actinomucor elegans(A.elegans)at different inoculation ratios on the volatile profiles and physicochemical properties of surimi were investigated.Generally,fermentation resulted in significant surimi protein hydrolysis as indicated by increased amino acid nitrogen,TCA-soluble peptide and free amino acid contents,simultaneously accompanied by decreases in hardness,gumminess and chewiness of surimi.Co-fermentation effectively improved the volatile profiles of surimi.Comparatively,a higher inoculation ratio of M.purpureus was favorable for the production of esters and ketones,whereas a higher proportion of A.elegans reduced the aldehyde contents,especially nonanal with fishy odor.Taken together,a 1:1 inoculation ratio of M.purpureus and A.elegans was more conductive to improve the aroma profiles of surimi,with a 77.2%reduction of aldehyde compared to unfermented surimi.
基金supported financially by the National Natural Science Foundation of China(31871869)the National Key R&D Program of China(2018YFD0901006).
文摘This study aimed to better understand the changes of fatty acids in dry-cured fish during storage,and to analyze the reactive carbonyl species(RCS)formation mechanism primarily from the standpoint of oxygen-derived free radical reactions interactions.Oleic acid and linoleic acid were the predominant unsaturated fatty acids in dry-cured fish.The content of unsaturated fatty acids in dry-cured fish increased over time at 4℃,while decreased at 25℃.Singlet oxygen,superoxide anion and hydroxyl-alkyl radical levels increased with time,and more free radicals were yielded in the samples held at 25℃.Redundancy analysis revealed that hydroxyl-alkyl radicals had the greatest influence on the oxidation of lipids.Hydroxyl-alkyl radicals and singlet oxygen levels were positively correlated with 4-hydroxy-2-nonenal(HNE),malondialdehyde(MDA),peroxide value and acid value levels,but adversely to 4-hydroxy-2-hexenal(HHE)and fatty acids levels.Moreover,HNE and MDA were both inversely linked with fatty acids contents.It is possible that the intermediates of lipid oxidation undergo oxidation,cleavage and other reactions due to free radical activity,resulting in the generation of aldehyde precursors.These findings help us further characterize the lipid oxidation and RCS formation mechanism in dry-cured fish during storage.
基金financially supported by the National Natural Science Foundation of China(No.31972104,32272473)Natural Science Foundation of Zhejiang Province(No.LR23C200003)National Key R&D Program of China(2019YFD0901603).
文摘The effect of cryoprotectants on the changes of physicochemical and structural properties of egg white protein(EWP)caused by repeated freeze-thaw(F-T)cycles was investigated.The cryoprotectants(4%trehalose+0.3%carrageenan,TC;1% xylo-oligosaccharide+0.3% carrageenan,XC;4% trehalose+1% xylo-oligosaccharide,TX)were added to the egg white,and stored at F-T for 1,3,and 5 cycles.The freezing protection effect of cryoprotectants on EWP was discussed by detecting carbonyl contents,total sulfhydryl group content,surface hydrophobicity,water-holding capacity(WHC)of heat-induced gel,SDS-PAGE and the secondary and tertiary structure of protein.The results showed that cryoprotectants could effectively inhibit the increase in surface hydrophobicity and carbonyl contents,and restrict the decrease in total sulfhydryl group content,WHC of heat-induced gel and endogenous fluorescence intensity(p<0.05).The results can provide reference for the application of cryoprotectants in frozen EWP using in food industry.
基金supported by the National Natural Science Foundation of China(No.32172241)Zhejiang Province“Three Rural Nine-Party”Science and Technology Cooperation Plan“Unveiling”Project(Grant No.2023SNJF067).
文摘In this investigation,the impacts of malondialdehyde(MDA),4-hydroxy-2-nonena(HNE),and their combinations on the structural characteristics of myofibrillar proteins(MP)were examined using endogenous fluorescence,Fourier transform infrared spectrum(FTIR)and Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis(SDS-PAGE).The potential binding mechanisms were also explored using LC-MS/MS and proteomics techniques.The findings indicated that various reactive carbonyl compounds(RCCs)displayed distinct oxidation performances in the oxidation of myofibrillar proteins.Samples containing HNE(HMP and MHMP groups)exhibited a more pronounced ability to oxidize MP than those containing MDA,as evidenced by their higher carbonyl content and lower sulfhydryl content.The MHMP group demonstrated the greatest surface hydrophobicity and Schiff base content but the lowest fluorescence intensity,suggesting that MDA and HNE synergistically altered MP conformation.Moreover,the alteration by RCCs notably modified the secondary structure of MP.Among these,HMP triggered the unfolding of MP molecules,resulting in the lowest α-helix and highest β-sheet ratio.The SDS‒PAGE results suggested that MDA oxidation promoted the crosslinking of MP molecules.At the same time,HNE caused the degradation of MP,as indicated by the decrease in the intensity of the high-molecular-weight bands.Proteomic analysis suggested that lysine residues distributed in the tail region of myosin were the main binding sites for MDA,whereas HNE preferentially modified methionine located at the myosin head.Additionally,HNE-induced protein degradation dominated RCC-induced oxidation reactions.These findings provide deeper insights into the mechanisms underlying quality changes induced by lipid oxidation products in MP-based food systems.
