Background Diphtheria,caused by Corynebacterium diphtheriae,remains a serious public health threat in areas with low vaccination coverage,despite global declines due to widespread immunization and improved clinical ma...Background Diphtheria,caused by Corynebacterium diphtheriae,remains a serious public health threat in areas with low vaccination coverage,despite global declines due to widespread immunization and improved clinical management.A major outbreak in Nigeria from 2022 to 2023 underscored the persistent risk in regions with inadequate vaccination.This study aims to assess the transmission dynamics of diphtheria in Kano State,the epicenter of the outbreak,by estimating key epidemiological parameters,including the generation time(GT),approximated in our study by serial interval,and effective reproduction number(R).Methods We analyzed diphtheria case-based data from Kano State,Nigeria,collected between August 18,2022,and November 29,2023.Generation time was approximated using serial intervals in confirmed cases within the same geographical areas.The effective reproduction number(R)was calculated using four methods:Maximum Likelihood Estimation(MLE),Exponential Growth(EG),Sequential Bayesian(SB),and Time-Dependent(TD),focusing on the period of maximum exponential growth.A sensitivity analysis was conducted to quantify the impact of uncertainties in the GT derived from our data on the estimation of R.Results Over the 469-day outbreak period,13,899 diphtheria cases were reported,with complete data available for 9406 cases.The estimated mean generation time was 2.8 days(SD=3.48 days),with 97%of cases having a GT of less than 21 days.The Restimates varied across methods,with the TD method producing the highest reproduction number of 2.21 during the peak growth period.Sensitivity analysis showed that Restimates increased with longer generation times.The models,except for the SB method,demonstrated a generally strong fit with the outbreak exponential growth period.Conclusion The ongoing diphtheria outbreak in Nigeria highlights the critical threat posed by declining vaccination coverage.This study provides valuable insights into the transmission dynamics of diphtheria during a prolonged and widespread outbreak,enhancing our understanding of disease spread in this context.While certain limitations may influence the interpretation of our estimates,the findings offer valuable information for future diphtheria outbreak preparedness and response in the African context.展开更多
Unlike other major crops,little research has been performed on tomato to reduce the generation time for speed breeding.We evaluated several agronomic treatments to reduce the generation time of tomato in the‘M82'...Unlike other major crops,little research has been performed on tomato to reduce the generation time for speed breeding.We evaluated several agronomic treatments to reduce the generation time of tomato in the‘M82'(determinate)and‘Moneymaker'(indeterminate)varieties and evaluated the best combination in conjunction with embryo rescue.Five container sizes with volumes of 0.2 L(XS),0.45 L(S),0.8 L(M),1.3 L(L),and6 L(XL),were evaluated in the first experiment under the autumn cycle.We found that plants grown in XL containers exhibited better development and required less time from sowing to anthesis(DSA)and from anthesis to fruit ripening(DAR).In the second experiment,using XL containers in the autumn-winter cycle,we evaluated the effects of cold priming at the cotyledonary stage,water stress,P supplementation,and K supplementation on generation time.Compared to the control,we found that cold priming significantly reduced the number of leaves,plant height to first the inflorescence,and DSA(2.7 d),whereas K supplementation reduced the DAR(8.8 d).In contrast,water stress and P supplementation did not significantly affect any of the measured traits like DAR,DSA or fruit set.To validate these data,in a third experiment with XL containers in the spring-summer cycle,the combination of cold priming and K supplementation was tested,confirming the significant effect of this combination on the reduction of generation time(2.9 d for DSA and 3.9 d for DAR)compared to the control.Embryo rescue during the cell expansion cycle(average of 22.0 d and 23.3 d after anthesis for‘M82'and‘Moneymaker',respectively)allowed the shortening of the generation time by 8.7 d in‘M82'and 11.6 d in‘Moneymaker'compared to the in planta fruit ripening.The combination of agronomic treatments with embryo rescue can effectively increase the number of generations per year from three to four for speed breeding of tomato.展开更多
BACKGROUND.The effective reproduction number Re(t)is a critical measure of epidemic potential.Re(t)can be calculated in near real time using an incidence time series and the generation time distribution:the time betwe...BACKGROUND.The effective reproduction number Re(t)is a critical measure of epidemic potential.Re(t)can be calculated in near real time using an incidence time series and the generation time distribution:the time between infection events in an infector-infectee pair.In calculating Re(t),the generation time distribution is often approximated by the serial interval distribution:the time between symptom onset in an infector-infectee pair.However,while generation time must be positive by definition,serial interval can be negative if transmission can occur before symptoms,such as in COVID-19,rendering such an approximation improper in some contexts.METHODS.We developed a method to infer the generation time distribution from parametric definitions of the serial interval and incubation period distributions.We then compared estimates of Re(t)for COVID-19 in the Greater Toronto Area of Canada using:negative-permitting versus non-negative serial interval distributions,versus the inferred generation time distribution.RESULTS.We estimated the generation time of COVID-19 to be Gamma-distributed with mean 3.99 and standard deviation 2.96 days.Relative to the generation time distribution,non-negative serial interval distribution caused overestimation of Re(t)due to larger mean,while negative-permitting serial interval distribution caused underestimation of Re(t)due to larger variance.IMPLICATIONS.Approximation of the generation time distribution of COVID-19 with non-negative or negative-permitting serial interval distributions when calculating Re(t)may result in over or underestimation of transmission potential,respectively.展开更多
The new generation of the times is the latest requirement for young people in the new era,and it is the latest training goal for young people put forward by the Party and the country in the face of the second centenni...The new generation of the times is the latest requirement for young people in the new era,and it is the latest training goal for young people put forward by the Party and the country in the face of the second centennial goal.At the 19th National Congress,it was put forward by the country that the concept of“new generation of the times”for the first time,indicating the training direction and theoretical guidance for the new generation of the times.The new age requires young people to have firm ideals and beliefs,excellent skills,and a great spirit of responsibility.The proposition of cultivating a new generation of the times is a deep exploration and summary of Marx’s theory of“all-round human development,”Lenin’s youth view and the education view of excellent traditional Chinese culture,and the proposition needs to strengthen the leadership of the Party,give play to the leading role of socialist core values,and the youth themselves should actively act to realize the transformation of theoretical and practical results.展开更多
China Debuts World’s Mightiest Centrifuge,Unleashing Ultra-intense Gravity。China launched the world’s largest centrifuge by capacity,which can generate 300 times Earth’s gravity and accommodate loads of up to 20 t...China Debuts World’s Mightiest Centrifuge,Unleashing Ultra-intense Gravity。China launched the world’s largest centrifuge by capacity,which can generate 300 times Earth’s gravity and accommodate loads of up to 20 tonnes,on September 29.展开更多
An environmentally friendly,low power consuming,sensitive and compact mercury analyzer was developed for the determination of mercury in water samples by integrating a thin film dielectric barrier discharge induced co...An environmentally friendly,low power consuming,sensitive and compact mercury analyzer was developed for the determination of mercury in water samples by integrating a thin film dielectric barrier discharge induced cold vapor reactor and a dielectric barrier discharge optical emission spectrometer into a small polymethyl methacrylate plate（10.5 cm length×8.0 cm width×1.2 cm height）.Mercury cold vapor was generated when standard or sample solutions with or without formic acid were introduced to the reactor to form thin film liquid and exposed to microplasma irradiation and subsequently separated from the liquid phase for transport to the microplasma and detection of its atomic emission.Limits of detection of 0.20 μg L^-1 and 2.6 μg L^-1 were obtained for the proposed system using or not using formic acid,respectively.Compared to the conventional microplasma optical emission spectrometry used for mercury analysis,this system not only retains the good limit of detection amenable to the determination of mercury in real samples,but also reduces power consumption,eliminates the generation of hydrogen and avoids the use of toxic or unstable reductant.Method validation was demonstrated by analysis of a certified reference material of water sample and three real water samples with good spike recoveries（88-102%）.展开更多
Translocations, especially assisted colonizations, of animals are increasingly used as a conservation management tool. In many cases, however, limited funding and other logistic challenges limit the number of individu...Translocations, especially assisted colonizations, of animals are increasingly used as a conservation management tool. In many cases, however, limited funding and other logistic challenges limit the number of individuals available for transloeation. In conservation genetics, small populations are predicted to rapidly lose genetic diversity which can deteriorate population survival. Thus, how worried should we be about the loss of genetic diversity when introducing small, isolated populations？ Historical species introductions provide a means to assess these issues. Here we review 13 studies of ＂assisted colonization-like＂ introductions of animals, where only a small known number of founders established an isolated population without secondary contact to the source population. We test which factors could be important in retaining genetic diversity in these cases. In many cases, loss in heterozygosity （-12.1%） was detected, and more seriously the loss in allelic richness （-27.8 %）. Number of founders seemed to have an effect but it also indicated that high population growth rate could help to retain genetic diversity, i.e. future management actions could be effective even with a limited number of founders if population growth would be enhanced. On the contrary, translocated organisms with longer generation times did not seem to retain more genetic diversity. We advocate that, where possible, future studies on translocated animals should report the loss of genetic diversity （both heterozygosity and allelic richness）, which is essential for meta-analyses like this one for deepening our understanding of the genetic consequences of assisted colonization, and justifying management decisions [Current Zoology 61 （5）： 827-834, 2015].展开更多
Taking the output power, thermal efficiency, and thermo-economic performance as the optimization objectives, we optimize the operation parameters of a thermodynamic system with combined endoreversible Carnot heat engi...Taking the output power, thermal efficiency, and thermo-economic performance as the optimization objectives, we optimize the operation parameters of a thermodynamic system with combined endoreversible Carnot heat engines in this paper. The applicabilities of the entropy generation minimization and entransy theory to the optimizations are discussed. For the discussed cases, only the entransy loss coefficient is always agreeable to the optimization of thermal efficiency. The applicabilities of the other discussed concepts to the optimizations are conditional. Different concepts and principles are needed for different optimization objectives, and the optimization principles have their application preconditions. When the preconditions are not satisfied, the principles may be not applicable.展开更多
Passively mode-locked fiber lasers （PMLFLs） could be not only used as simple and economic ultrashort pulse sources but also as an ideal platform for exploring the nonlinear dynamics of dissipative solitons such as b...Passively mode-locked fiber lasers （PMLFLs） could be not only used as simple and economic ultrashort pulse sources but also as an ideal platform for exploring the nonlinear dynamics of dissipative solitons such as bound solitons, soliton rains, noise-like pulses, sideband-controllable solitons, soliton resonance,展开更多
Generation of wind power time series is an important foundational task for assisting electric power system planning and mak- ing decision. By analyzing the characteristics of wind power persistence and variation, th!....Generation of wind power time series is an important foundational task for assisting electric power system planning and mak- ing decision. By analyzing the characteristics of wind power persistence and variation, th!.s paper proposes an improved Mar- kov chain Monte Carlo （MCMC） method, identified as the PV-MC method, for the direct generation of a synthetic series of wind power output. On the basis of the MCMC method, duration time and variation features are concluded in PV-MC method, gaining a more comprehensive reflection of wind power characteristics in the generated wind power time series. First, the wind power state series is generated to meet the state transition matrix based on the definition of the wind power state. Then, the time duration of each state in the series is determined by its respective duration character. Finally, the variation characteristic is used to convert the state series to a wind power time series. A significant amount of simulations are performed based on the PV-MC and MCMC methods and are then compared for 25 wind farms at 6 different locations throughout the world. The sim- ulation results show that the PV-MC method offers an excellent fit for the time domain features （persistence and variation characteristic） while holding other statistic features （mean value, variance, autocorrelation coefficient （ACC） and probability density function （PDF）） close to the MCMC method.展开更多
Objectives:Optimization of ultrasonic-assisted freezing of Penaeus chinensis by response surface methodology was studied in order to(1)obtain frozen Penaeus chinensis of high quality and(2)provide practical guidance f...Objectives:Optimization of ultrasonic-assisted freezing of Penaeus chinensis by response surface methodology was studied in order to(1)obtain frozen Penaeus chinensis of high quality and(2)provide practical guidance for the application of ultrasonic-assisted freezing in Penaeus chinensis.Materials and Methods:Three independent and major variables were selected,including initial ultrasonic temperature(℃),ultrasonic power(W)and ultrasonic time(s on/2 s off).On the basis of one-factor experiments,17 groups of experiments were established by response surface methodology according to Box-Behnken design.Using multiple regression analysis the experimental data were fitted into a second-order polynomial equation,which was tested by proper statistical methods.Results:The optimal ultrasonic conditions were as follows:initial ultrasonic temperature 0℃,ultrasonic power 180 W,ultrasonic time 5 son/2 s off.Under the optimization conditions,the time of passing through maximum ice crystal generation zone was 105.500 s,which was very close to the predictive passage time of 101.541 s.Conclusions:Initial ultrasonic temperature,ultrasonic time and ultrasonic power played an important role in the process of ultrasonic-assisted freezing of Penaeus chinensis.Response surface methodology was used to optimize the three factors in ultrasonic-assisted freezing,which could greatly shorten the time of passing through the maximum ice crystal generation zone and maintain the tissue structure of Penaeus chinensis well.展开更多
文摘Background Diphtheria,caused by Corynebacterium diphtheriae,remains a serious public health threat in areas with low vaccination coverage,despite global declines due to widespread immunization and improved clinical management.A major outbreak in Nigeria from 2022 to 2023 underscored the persistent risk in regions with inadequate vaccination.This study aims to assess the transmission dynamics of diphtheria in Kano State,the epicenter of the outbreak,by estimating key epidemiological parameters,including the generation time(GT),approximated in our study by serial interval,and effective reproduction number(R).Methods We analyzed diphtheria case-based data from Kano State,Nigeria,collected between August 18,2022,and November 29,2023.Generation time was approximated using serial intervals in confirmed cases within the same geographical areas.The effective reproduction number(R)was calculated using four methods:Maximum Likelihood Estimation(MLE),Exponential Growth(EG),Sequential Bayesian(SB),and Time-Dependent(TD),focusing on the period of maximum exponential growth.A sensitivity analysis was conducted to quantify the impact of uncertainties in the GT derived from our data on the estimation of R.Results Over the 469-day outbreak period,13,899 diphtheria cases were reported,with complete data available for 9406 cases.The estimated mean generation time was 2.8 days(SD=3.48 days),with 97%of cases having a GT of less than 21 days.The Restimates varied across methods,with the TD method producing the highest reproduction number of 2.21 during the peak growth period.Sensitivity analysis showed that Restimates increased with longer generation times.The models,except for the SB method,demonstrated a generally strong fit with the outbreak exponential growth period.Conclusion The ongoing diphtheria outbreak in Nigeria highlights the critical threat posed by declining vaccination coverage.This study provides valuable insights into the transmission dynamics of diphtheria during a prolonged and widespread outbreak,enhancing our understanding of disease spread in this context.While certain limitations may influence the interpretation of our estimates,the findings offer valuable information for future diphtheria outbreak preparedness and response in the African context.
基金funded by the European Commission H2020 Research and Innovation Programme through the HARNESSTOM innovation action(Grant No.101000716)Grant CIPROM/2021/020(project SOLECO)funded by Conselleria d’Innovació,Universitats,Ciència i Societat Digital(Generalitat Valenciana,Spain)Pietro Gramazio received a post-doctoral fellowship(Grant No.RYC2021-031999-I)funded by MCIN/AEI/10.13039/501100011033 and by“European Union NextGenerationEU/PRTR”。
文摘Unlike other major crops,little research has been performed on tomato to reduce the generation time for speed breeding.We evaluated several agronomic treatments to reduce the generation time of tomato in the‘M82'(determinate)and‘Moneymaker'(indeterminate)varieties and evaluated the best combination in conjunction with embryo rescue.Five container sizes with volumes of 0.2 L(XS),0.45 L(S),0.8 L(M),1.3 L(L),and6 L(XL),were evaluated in the first experiment under the autumn cycle.We found that plants grown in XL containers exhibited better development and required less time from sowing to anthesis(DSA)and from anthesis to fruit ripening(DAR).In the second experiment,using XL containers in the autumn-winter cycle,we evaluated the effects of cold priming at the cotyledonary stage,water stress,P supplementation,and K supplementation on generation time.Compared to the control,we found that cold priming significantly reduced the number of leaves,plant height to first the inflorescence,and DSA(2.7 d),whereas K supplementation reduced the DAR(8.8 d).In contrast,water stress and P supplementation did not significantly affect any of the measured traits like DAR,DSA or fruit set.To validate these data,in a third experiment with XL containers in the spring-summer cycle,the combination of cold priming and K supplementation was tested,confirming the significant effect of this combination on the reduction of generation time(2.9 d for DSA and 3.9 d for DAR)compared to the control.Embryo rescue during the cell expansion cycle(average of 22.0 d and 23.3 d after anthesis for‘M82'and‘Moneymaker',respectively)allowed the shortening of the generation time by 8.7 d in‘M82'and 11.6 d in‘Moneymaker'compared to the in planta fruit ripening.The combination of agronomic treatments with embryo rescue can effectively increase the number of generations per year from three to four for speed breeding of tomato.
基金The study was supported by:the Natural Sciences and Engineering Research Council of Canada(NSERC CGS-D)Ontario Early Researcher Award No.ER17-13-043(Canada)the 2020 COVID-19 Centred Research Award from the St Michael’s Hospital Foundation Research Innovation Council(Canada).
文摘BACKGROUND.The effective reproduction number Re(t)is a critical measure of epidemic potential.Re(t)can be calculated in near real time using an incidence time series and the generation time distribution:the time between infection events in an infector-infectee pair.In calculating Re(t),the generation time distribution is often approximated by the serial interval distribution:the time between symptom onset in an infector-infectee pair.However,while generation time must be positive by definition,serial interval can be negative if transmission can occur before symptoms,such as in COVID-19,rendering such an approximation improper in some contexts.METHODS.We developed a method to infer the generation time distribution from parametric definitions of the serial interval and incubation period distributions.We then compared estimates of Re(t)for COVID-19 in the Greater Toronto Area of Canada using:negative-permitting versus non-negative serial interval distributions,versus the inferred generation time distribution.RESULTS.We estimated the generation time of COVID-19 to be Gamma-distributed with mean 3.99 and standard deviation 2.96 days.Relative to the generation time distribution,non-negative serial interval distribution caused overestimation of Re(t)due to larger mean,while negative-permitting serial interval distribution caused underestimation of Re(t)due to larger variance.IMPLICATIONS.Approximation of the generation time distribution of COVID-19 with non-negative or negative-permitting serial interval distributions when calculating Re(t)may result in over or underestimation of transmission potential,respectively.
文摘The new generation of the times is the latest requirement for young people in the new era,and it is the latest training goal for young people put forward by the Party and the country in the face of the second centennial goal.At the 19th National Congress,it was put forward by the country that the concept of“new generation of the times”for the first time,indicating the training direction and theoretical guidance for the new generation of the times.The new age requires young people to have firm ideals and beliefs,excellent skills,and a great spirit of responsibility.The proposition of cultivating a new generation of the times is a deep exploration and summary of Marx’s theory of“all-round human development,”Lenin’s youth view and the education view of excellent traditional Chinese culture,and the proposition needs to strengthen the leadership of the Party,give play to the leading role of socialist core values,and the youth themselves should actively act to realize the transformation of theoretical and practical results.
文摘China Debuts World’s Mightiest Centrifuge,Unleashing Ultra-intense Gravity。China launched the world’s largest centrifuge by capacity,which can generate 300 times Earth’s gravity and accommodate loads of up to 20 tonnes,on September 29.
基金the National Natural Science Foundation of China(No.21575092)for financial support
文摘An environmentally friendly,low power consuming,sensitive and compact mercury analyzer was developed for the determination of mercury in water samples by integrating a thin film dielectric barrier discharge induced cold vapor reactor and a dielectric barrier discharge optical emission spectrometer into a small polymethyl methacrylate plate（10.5 cm length×8.0 cm width×1.2 cm height）.Mercury cold vapor was generated when standard or sample solutions with or without formic acid were introduced to the reactor to form thin film liquid and exposed to microplasma irradiation and subsequently separated from the liquid phase for transport to the microplasma and detection of its atomic emission.Limits of detection of 0.20 μg L^-1 and 2.6 μg L^-1 were obtained for the proposed system using or not using formic acid,respectively.Compared to the conventional microplasma optical emission spectrometry used for mercury analysis,this system not only retains the good limit of detection amenable to the determination of mercury in real samples,but also reduces power consumption,eliminates the generation of hydrogen and avoids the use of toxic or unstable reductant.Method validation was demonstrated by analysis of a certified reference material of water sample and three real water samples with good spike recoveries（88-102%）.
文摘Translocations, especially assisted colonizations, of animals are increasingly used as a conservation management tool. In many cases, however, limited funding and other logistic challenges limit the number of individuals available for transloeation. In conservation genetics, small populations are predicted to rapidly lose genetic diversity which can deteriorate population survival. Thus, how worried should we be about the loss of genetic diversity when introducing small, isolated populations？ Historical species introductions provide a means to assess these issues. Here we review 13 studies of ＂assisted colonization-like＂ introductions of animals, where only a small known number of founders established an isolated population without secondary contact to the source population. We test which factors could be important in retaining genetic diversity in these cases. In many cases, loss in heterozygosity （-12.1%） was detected, and more seriously the loss in allelic richness （-27.8 %）. Number of founders seemed to have an effect but it also indicated that high population growth rate could help to retain genetic diversity, i.e. future management actions could be effective even with a limited number of founders if population growth would be enhanced. On the contrary, translocated organisms with longer generation times did not seem to retain more genetic diversity. We advocate that, where possible, future studies on translocated animals should report the loss of genetic diversity （both heterozygosity and allelic richness）, which is essential for meta-analyses like this one for deepening our understanding of the genetic consequences of assisted colonization, and justifying management decisions [Current Zoology 61 （5）： 827-834, 2015].
基金Project supported by the National Natural Science Foundation of China(Grant No.51376101)the Science Fund for Creative Research Groups,China(Grant No.51321002)
文摘Taking the output power, thermal efficiency, and thermo-economic performance as the optimization objectives, we optimize the operation parameters of a thermodynamic system with combined endoreversible Carnot heat engines in this paper. The applicabilities of the entropy generation minimization and entransy theory to the optimizations are discussed. For the discussed cases, only the entransy loss coefficient is always agreeable to the optimization of thermal efficiency. The applicabilities of the other discussed concepts to the optimizations are conditional. Different concepts and principles are needed for different optimization objectives, and the optimization principles have their application preconditions. When the preconditions are not satisfied, the principles may be not applicable.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.11674177,61322510,and 61640408)Tianjin Natural Science Foundation(Nos.16JCZDJC31000 and 14JCZDJC31300)
文摘Passively mode-locked fiber lasers （PMLFLs） could be not only used as simple and economic ultrashort pulse sources but also as an ideal platform for exploring the nonlinear dynamics of dissipative solitons such as bound solitons, soliton rains, noise-like pulses, sideband-controllable solitons, soliton resonance,
基金supported by the National Natural Science Foundation of China(Grant No.51377027)the National Basic Research Program of China("973"Project)(Grant No.2012CB215104)ABB(China)Ltd
文摘Generation of wind power time series is an important foundational task for assisting electric power system planning and mak- ing decision. By analyzing the characteristics of wind power persistence and variation, th!.s paper proposes an improved Mar- kov chain Monte Carlo （MCMC） method, identified as the PV-MC method, for the direct generation of a synthetic series of wind power output. On the basis of the MCMC method, duration time and variation features are concluded in PV-MC method, gaining a more comprehensive reflection of wind power characteristics in the generated wind power time series. First, the wind power state series is generated to meet the state transition matrix based on the definition of the wind power state. Then, the time duration of each state in the series is determined by its respective duration character. Finally, the variation characteristic is used to convert the state series to a wind power time series. A significant amount of simulations are performed based on the PV-MC and MCMC methods and are then compared for 25 wind farms at 6 different locations throughout the world. The sim- ulation results show that the PV-MC method offers an excellent fit for the time domain features （persistence and variation characteristic） while holding other statistic features （mean value, variance, autocorrelation coefficient （ACC） and probability density function （PDF）） close to the MCMC method.
基金the National Key Research and Development of China(No.2016YFD0400102)National Natural Science Foundation of China(No.31671918).
文摘Objectives:Optimization of ultrasonic-assisted freezing of Penaeus chinensis by response surface methodology was studied in order to(1)obtain frozen Penaeus chinensis of high quality and(2)provide practical guidance for the application of ultrasonic-assisted freezing in Penaeus chinensis.Materials and Methods:Three independent and major variables were selected,including initial ultrasonic temperature(℃),ultrasonic power(W)and ultrasonic time(s on/2 s off).On the basis of one-factor experiments,17 groups of experiments were established by response surface methodology according to Box-Behnken design.Using multiple regression analysis the experimental data were fitted into a second-order polynomial equation,which was tested by proper statistical methods.Results:The optimal ultrasonic conditions were as follows:initial ultrasonic temperature 0℃,ultrasonic power 180 W,ultrasonic time 5 son/2 s off.Under the optimization conditions,the time of passing through maximum ice crystal generation zone was 105.500 s,which was very close to the predictive passage time of 101.541 s.Conclusions:Initial ultrasonic temperature,ultrasonic time and ultrasonic power played an important role in the process of ultrasonic-assisted freezing of Penaeus chinensis.Response surface methodology was used to optimize the three factors in ultrasonic-assisted freezing,which could greatly shorten the time of passing through the maximum ice crystal generation zone and maintain the tissue structure of Penaeus chinensis well.
