In this paper, to complete the global dynamics of a multi-strains SIS epidemic model, we establish a precise result on coexistence for the cases of the partial and complete duplicated multiple largest reproduction rat...In this paper, to complete the global dynamics of a multi-strains SIS epidemic model, we establish a precise result on coexistence for the cases of the partial and complete duplicated multiple largest reproduction ratios for this model.展开更多
Douchi is traditionally produced through natural fermentation without intentionally inoculated microorganisms.To improve the fermentation process,this study aimed to investigate the effects on microbiota and flavor du...Douchi is traditionally produced through natural fermentation without intentionally inoculated microorganisms.To improve the fermentation process,this study aimed to investigate the effects on microbiota and flavor during Douchi fermentation using selected autochthonous microorganisms,Bacillus amyloliquefaciens B9 and Pichia kudriavzevii Y18.Results showed that bacteria dominated the fermentation process,while fungi played a supplementary role.Genus-level analysis identified Bacillus as the most prevalent genus during fermentation,while Pichia surged on day 15 and reached peak relative abundance by day 22.During post-fermentation,the total content of volatile compounds increased by 126.91%,and the content of esters rose significantly to 1190.90μg/kg by day 30.Compared with day 0,six key volatile flavor compounds with odor activity values(OAV)exceeding 1 were newly produced,indicating that the inoculated microorganisms significantly contributed to their formation.Non-volatile metabolites exhibited varying trends,with their accumulations stabilizing in the later stages of fermentation.Notably,amino acids and dipeptides accumulated significantly during fermentation,enhancing the nutritional and flavor profiles of Douchi.The construction of the metabolic network highlighted that amino acid and carbohydrate metabolism were pivotal pathways for flavor enhancement during Douchi postfermentation.Furthermore,pyruvate and acetyl-CoA were critical in Douchi fermentation and acted as core intermediates for flavor compound production,participating in amino acid biosynthesis,the tricarboxylic acid cycle,and fatty acid biosynthesis.Additionally,Pichia played a role in the biosynthesis of γ-Aminobutyric acid.This study systematically explored the multidimensional characteristics of Douchi post-fermentation,bridging the gap between descriptive research and mechanism-driven fermentation control strategies.展开更多
Ge/SiGe heterostructure quantum wells play a pivotal role in the pursuit of scalable silicon-based qubits.The varying compressive strains within these quantum wells profoundly influence the physical characteristics of...Ge/SiGe heterostructure quantum wells play a pivotal role in the pursuit of scalable silicon-based qubits.The varying compressive strains within these quantum wells profoundly influence the physical characteristics of the qubits,yet this factor remains largely unexplored,driving our research endeavor.In this study,we utilized RP-CVD(Reduced Pressure Chemical Vapor Deposition)to grow Ge quantum wells with varied compressive strain,proposing growth schemes for lightly-strained(ε∥=-0.43%)QW(quantum well),standard-strained(ε∥=-0.61%)QW,and heavily-strained(ε∥=-1.19%)QW.Through comprehensive material characterization,particularly employing the low-temperature magneto-transport measurements,we derived the percolation densities ranging from 4.7×10^(10) to 14.2×10^(10) cm^(-2) and mobilities from 3.382×10^(5) to 7.301×10^(5) cm^(2)∙V^(-1)∙s^(-1).Combined with the first-principles calculations,our analysis delves into the trends in effective mass and percolation density at low temperatures,shedding light on the impact of quantum effects on band structures and the interplay between structural components and wave functions.This research offers a comprehensive investigation into the intrinsic mechanisms governing complex multi-strained quantum wells,spanning growth,characterization,and computational perspectives,thereby establishing a strategy for the growth of high-quality strained quantum wells.展开更多
The widespread use of polymers has made our lives increasingly convenient by offering a more convenient and dependable material.However,the challenge of efficiently decomposing these materials has resulted in a surge ...The widespread use of polymers has made our lives increasingly convenient by offering a more convenient and dependable material.However,the challenge of efficiently decomposing these materials has resulted in a surge of polymer waste,posing environment and health risk.Currently,landfill and incineration treatment approaches have notable shortcomings,prompting a shift towards more eco-friendly and sustainable biodegradation approaches.Biodegradation primarily relies on microorganisms,with research focusing on both solitary bacterial strain and multi-strain communities for polymer biodegradation.Furthermore,directed evolution and rational design of enzyme have significantly contributed to the polymer biodegradation process.However,previous reviews often undervaluing the role of multi-strain communities.In this review,we assess the current state of these three significant fields of research,provide practical solutions to issues with polymer biodegradation,and outline potential future directions for the subject.Ultimately,biodegradation,whether facilitated by single bacteria,multi-strain communities,or engineered enzymes,now represents the most effective method for managing waste polymers.展开更多
Listeria monocytogenes is a resilient foodborne pathogen that forms biofilms,allowing it to persist and thrive in food-processing environments.This study examined the structural characteristics of biofilms formed by t...Listeria monocytogenes is a resilient foodborne pathogen that forms biofilms,allowing it to persist and thrive in food-processing environments.This study examined the structural characteristics of biofilms formed by three L.monocytogenes strains,their transfer to cold-smoked rainbow trout fillets,and the bioprotective effects of two lactic acid bacteria(LAB)cocktails during storage.Confocal microscopy revealed that mixed-strain biofilms exhibited more homogeneous structures than single-strain biofilms,emphasizing their relevance in contamina-tion events.Transfer experiments demonstrated that 87.52%of L.monocytogenes biofilm cells were transferred from stainless steel to cold-smoked rainbow trout fillets after 90 s of contact,highlighting a significant contamination risk.The commercial LAB cocktail containing Lactococcus lactis subsp.lactis and Leuconostoc carnosum effectively inhibited L.monocytogenes growth under both static(5◦C)and dynamic(4-20◦C)conditions,reducing bacterial concentrations by>0.70 and>1.24 log CFU/g respectively,after 21 days.The inhibitory effect was likely driven by bacteriocin production,particularly leucocin,potentially enhanced by diacetyl production.LAB-based bioprotection effectively controlled L.monocytogenes without producing significant changes in pH or water activity.These findings highlight the need for multi-strain biofilm models to better understand contamination dynamics and support LAB-based bioprotection as a natural,effective strategy for improving food safety in smoked fish products.展开更多
As a traditional staple food,Chinese steamed bread(CSB)with fermented glutinous rice procedure enjoys a long history with good qualities(specific volume≥4.0 mL/g,especially)due to the unique leavened dough procedure ...As a traditional staple food,Chinese steamed bread(CSB)with fermented glutinous rice procedure enjoys a long history with good qualities(specific volume≥4.0 mL/g,especially)due to the unique leavened dough procedure with glutinous rice wine(GRW)as a starter.This research reveals the uniqueness of preparing multi-stage fer-mented GRW-dough and GRW-CSB without commercial yeast addition.The effects of recipe formulations and rice porridge on the core mash and liquid fermentation(MLF)process and CSB qualities were also explored.The results showed that the rice porridge and wheat bran provided essential nutrients for microbial propagation,and the essence of MLF was the enlarged cultivation of multiple strains,accompanied by saccharification and fermentation simultaneously.Generally,the fermented glutinous rice procedure is similar to the sourdough procedure.The potential of alkaline neutralization in sourdough to improve CSB qualities was investigated.The addition of sodium carbonate could increase the GRW-dough pH to 6.2-6.7,but it did not significantly impact sensory evaluation and specific volume of GRW-CSB(p>0.05).Furthermore,the increasing rice porridge could replace the role of an alkali.Our findings suggest that pH adjustment is not necessary for GRW-leavened dough within the range of 5.2-5.5 to produce high-quality CSB.展开更多
This experiment was conducted to evaluate the effect of milk or molasses kefir as a probiotic on growth performance, carcass traits, serum biochemistry and humoral immune responses in broiler chickens. A total of 192 ...This experiment was conducted to evaluate the effect of milk or molasses kefir as a probiotic on growth performance, carcass traits, serum biochemistry and humoral immune responses in broiler chickens. A total of 192 one-d-old as hatched broiler chicks(Ross 308) were randomly allotted to 4 treatments, each with 4 replicate pens of 12 chicks. The following treatments were applied: 1) a basal diet(C) and normal drinking water, 2) 2% milk kefir in drinking water, 3) 2% molasses kefir in drinking water, and 4) the diet C supplemented with commercial probiotic. At d 42, eight birds per treatment were killed for determination of carcass traits. Broilers at 28 days of age were bled for measuring antibody titers against Newcastle disease virus(NDV) and avian influenza virus(AIV), at 30 days of age for antibody titers against sheep red blood cell(SRBC), and at 42 days of age for biochemical analysis. Supplementing 2%milk kefir increased body weight of broilers at 28 and 42 days of age(P < 0.05). Supplementing 2%molasses kefir improved feed conversation ratio(FCR) of broilers during growth period(P < 0.05), but FCR of broilers in other periods was not affected. Daily feed intake, internal organ weights, and carcass traits were not influenced by the treatments except for small intestine and ceca length. Small intestinal length significantly decreased in broilers supplemented with milk and molasses kefir(P < 0.05). Molasses kefir supplementation significantly(P < 0.05) increased antibody titer against SRBC at 31 days of age but other immune related parameters were not statistically different among treatments. Biochemical parameters including serum protein, albumin, and triglyceride concentrations were not statistically(P> 0.05) influenced. Broilers supplemented with molasses kefir, had a significantly lower concentration of serum total cholesterol, low density lipoprotein cholesterol and elevated high density lipoprotein cholesterol at 42 days of age(P < 0.05). In conclusion, the results indicated that inclusion of 2% milk kefir in drinking water would improve growth performance of broiler chickens.展开更多
In this paper,we study a multi-strain SEIR epidemic model with both bilinear and nonmonotone incidence functions.Under biologically motivated assumptions,we show that the model has two basic reproduction numbers that ...In this paper,we study a multi-strain SEIR epidemic model with both bilinear and nonmonotone incidence functions.Under biologically motivated assumptions,we show that the model has two basic reproduction numbers that we noted R0,1 and R0,2;and four equilibrium points.Using the Lyapunov method,we prove that if R0,1 and R0,2 are less than one then the disease-free equilibrium is Globally Asymptotically Stable,thus the disease will be eradicated.However,if one of the two basic reproduction numbers is greater than one,then the strain that persists is that with the larger basic reproduction number.And finally if both of the two basic reproduction numbers are equal or greater than one then the total endemic equilibrium is globally asymptotically stable.A numerical simulation is also presented to illustrate the influence of the psychological effect,of people to infection,on the spread of the disease in the population.This simulation can be used to determine the status of different diseases in a region using the corresponding data and infectious disease parameters.展开更多
A vaccine breakthrough infection and a rebound infection cases of COVID-19 are studied and analyzed for the ten U.S.Department of Health and Human Services(HHS)regions and the United States as a nation in this work.An...A vaccine breakthrough infection and a rebound infection cases of COVID-19 are studied and analyzed for the ten U.S.Department of Health and Human Services(HHS)regions and the United States as a nation in this work.An innovative multi-strain susceptible-vacci-nated-exposed-asymptomatic-symptomatic-recovered(SVEAIR)epidemic model is devel-oped for this purpose for a population assumed to be susceptible to n-different variants of the disease,and those who are vaccinated and recovered from a specific strain k(kn)of the disease are immune to present strain and its predecessors j=1,2,…,k,but can still be infected by newer emerging strains j=k+1,k+2,…,n.The model is used to estimate epidemiological parameters,namely,the latent and infectious periods,the transmission rates,vaccination rates,recovery rates for each of the Delta B.1.617.2,Omicron B.1.1.529,and lineages BA.2,BA.2.12.1,BA.4,BA.5,BA.1.1,BA.4.6,and BA.5.2.6 for the United States and for each of the ten HHS regions.The transmission rate is estimated for both the asymptomatic and symptomatic cases.The effect of vaccines on each strain is analyzed.Condition that guarantees existence of an endemic with certain number of strains is derived and used to describe the endemic state of the population.展开更多
文摘In this paper, to complete the global dynamics of a multi-strains SIS epidemic model, we establish a precise result on coexistence for the cases of the partial and complete duplicated multiple largest reproduction ratios for this model.
基金supported by the National Key Research and Devel-opment Program of the Ministry of Science and Technology(Project No.2022YFE0120800).
文摘Douchi is traditionally produced through natural fermentation without intentionally inoculated microorganisms.To improve the fermentation process,this study aimed to investigate the effects on microbiota and flavor during Douchi fermentation using selected autochthonous microorganisms,Bacillus amyloliquefaciens B9 and Pichia kudriavzevii Y18.Results showed that bacteria dominated the fermentation process,while fungi played a supplementary role.Genus-level analysis identified Bacillus as the most prevalent genus during fermentation,while Pichia surged on day 15 and reached peak relative abundance by day 22.During post-fermentation,the total content of volatile compounds increased by 126.91%,and the content of esters rose significantly to 1190.90μg/kg by day 30.Compared with day 0,six key volatile flavor compounds with odor activity values(OAV)exceeding 1 were newly produced,indicating that the inoculated microorganisms significantly contributed to their formation.Non-volatile metabolites exhibited varying trends,with their accumulations stabilizing in the later stages of fermentation.Notably,amino acids and dipeptides accumulated significantly during fermentation,enhancing the nutritional and flavor profiles of Douchi.The construction of the metabolic network highlighted that amino acid and carbohydrate metabolism were pivotal pathways for flavor enhancement during Douchi postfermentation.Furthermore,pyruvate and acetyl-CoA were critical in Douchi fermentation and acted as core intermediates for flavor compound production,participating in amino acid biosynthesis,the tricarboxylic acid cycle,and fatty acid biosynthesis.Additionally,Pichia played a role in the biosynthesis of γ-Aminobutyric acid.This study systematically explored the multidimensional characteristics of Douchi post-fermentation,bridging the gap between descriptive research and mechanism-driven fermentation control strategies.
基金supported by the Innovation Program for Quantum Science and Technology (Project ID.2021ZD0302301)the National Natural Science Foundation of China (Grant No.6240033549).
文摘Ge/SiGe heterostructure quantum wells play a pivotal role in the pursuit of scalable silicon-based qubits.The varying compressive strains within these quantum wells profoundly influence the physical characteristics of the qubits,yet this factor remains largely unexplored,driving our research endeavor.In this study,we utilized RP-CVD(Reduced Pressure Chemical Vapor Deposition)to grow Ge quantum wells with varied compressive strain,proposing growth schemes for lightly-strained(ε∥=-0.43%)QW(quantum well),standard-strained(ε∥=-0.61%)QW,and heavily-strained(ε∥=-1.19%)QW.Through comprehensive material characterization,particularly employing the low-temperature magneto-transport measurements,we derived the percolation densities ranging from 4.7×10^(10) to 14.2×10^(10) cm^(-2) and mobilities from 3.382×10^(5) to 7.301×10^(5) cm^(2)∙V^(-1)∙s^(-1).Combined with the first-principles calculations,our analysis delves into the trends in effective mass and percolation density at low temperatures,shedding light on the impact of quantum effects on band structures and the interplay between structural components and wave functions.This research offers a comprehensive investigation into the intrinsic mechanisms governing complex multi-strained quantum wells,spanning growth,characterization,and computational perspectives,thereby establishing a strategy for the growth of high-quality strained quantum wells.
基金supported by the National Natural Science Foundation of China(22078011,21908003,and 32022002)the National Key Research and Development Program of China(2021YFC2100600)+1 种基金the seed funding of China Petrochemical Corporation(Sinopec Group)(223260)the Fundamental Research Funds for the Central Universities(QNTD2023-01).
文摘The widespread use of polymers has made our lives increasingly convenient by offering a more convenient and dependable material.However,the challenge of efficiently decomposing these materials has resulted in a surge of polymer waste,posing environment and health risk.Currently,landfill and incineration treatment approaches have notable shortcomings,prompting a shift towards more eco-friendly and sustainable biodegradation approaches.Biodegradation primarily relies on microorganisms,with research focusing on both solitary bacterial strain and multi-strain communities for polymer biodegradation.Furthermore,directed evolution and rational design of enzyme have significantly contributed to the polymer biodegradation process.However,previous reviews often undervaluing the role of multi-strain communities.In this review,we assess the current state of these three significant fields of research,provide practical solutions to issues with polymer biodegradation,and outline potential future directions for the subject.Ultimately,biodegradation,whether facilitated by single bacteria,multi-strain communities,or engineered enzymes,now represents the most effective method for managing waste polymers.
基金funded by the Ministry of Science and Innovation of the Spanish Government through the Research Projects ASEQURA(PID-2019-108420RB-C31)and ASEQURA2(PID2023-152192OB-C22)the Predoctoral Research Training Contract(PRE2020-092741)Funding for the open access charge was provided by Universidad de Cordoba/CBUA.
文摘Listeria monocytogenes is a resilient foodborne pathogen that forms biofilms,allowing it to persist and thrive in food-processing environments.This study examined the structural characteristics of biofilms formed by three L.monocytogenes strains,their transfer to cold-smoked rainbow trout fillets,and the bioprotective effects of two lactic acid bacteria(LAB)cocktails during storage.Confocal microscopy revealed that mixed-strain biofilms exhibited more homogeneous structures than single-strain biofilms,emphasizing their relevance in contamina-tion events.Transfer experiments demonstrated that 87.52%of L.monocytogenes biofilm cells were transferred from stainless steel to cold-smoked rainbow trout fillets after 90 s of contact,highlighting a significant contamination risk.The commercial LAB cocktail containing Lactococcus lactis subsp.lactis and Leuconostoc carnosum effectively inhibited L.monocytogenes growth under both static(5◦C)and dynamic(4-20◦C)conditions,reducing bacterial concentrations by>0.70 and>1.24 log CFU/g respectively,after 21 days.The inhibitory effect was likely driven by bacteriocin production,particularly leucocin,potentially enhanced by diacetyl production.LAB-based bioprotection effectively controlled L.monocytogenes without producing significant changes in pH or water activity.These findings highlight the need for multi-strain biofilm models to better understand contamination dynamics and support LAB-based bioprotection as a natural,effective strategy for improving food safety in smoked fish products.
基金funded by the program for the National Natural Science Foundation of China(No.32101988)the Postdoctoral Research Foundation of China(No.2019 M651706).
文摘As a traditional staple food,Chinese steamed bread(CSB)with fermented glutinous rice procedure enjoys a long history with good qualities(specific volume≥4.0 mL/g,especially)due to the unique leavened dough procedure with glutinous rice wine(GRW)as a starter.This research reveals the uniqueness of preparing multi-stage fer-mented GRW-dough and GRW-CSB without commercial yeast addition.The effects of recipe formulations and rice porridge on the core mash and liquid fermentation(MLF)process and CSB qualities were also explored.The results showed that the rice porridge and wheat bran provided essential nutrients for microbial propagation,and the essence of MLF was the enlarged cultivation of multiple strains,accompanied by saccharification and fermentation simultaneously.Generally,the fermented glutinous rice procedure is similar to the sourdough procedure.The potential of alkaline neutralization in sourdough to improve CSB qualities was investigated.The addition of sodium carbonate could increase the GRW-dough pH to 6.2-6.7,but it did not significantly impact sensory evaluation and specific volume of GRW-CSB(p>0.05).Furthermore,the increasing rice porridge could replace the role of an alkali.Our findings suggest that pH adjustment is not necessary for GRW-leavened dough within the range of 5.2-5.5 to produce high-quality CSB.
文摘This experiment was conducted to evaluate the effect of milk or molasses kefir as a probiotic on growth performance, carcass traits, serum biochemistry and humoral immune responses in broiler chickens. A total of 192 one-d-old as hatched broiler chicks(Ross 308) were randomly allotted to 4 treatments, each with 4 replicate pens of 12 chicks. The following treatments were applied: 1) a basal diet(C) and normal drinking water, 2) 2% milk kefir in drinking water, 3) 2% molasses kefir in drinking water, and 4) the diet C supplemented with commercial probiotic. At d 42, eight birds per treatment were killed for determination of carcass traits. Broilers at 28 days of age were bled for measuring antibody titers against Newcastle disease virus(NDV) and avian influenza virus(AIV), at 30 days of age for antibody titers against sheep red blood cell(SRBC), and at 42 days of age for biochemical analysis. Supplementing 2%milk kefir increased body weight of broilers at 28 and 42 days of age(P < 0.05). Supplementing 2%molasses kefir improved feed conversation ratio(FCR) of broilers during growth period(P < 0.05), but FCR of broilers in other periods was not affected. Daily feed intake, internal organ weights, and carcass traits were not influenced by the treatments except for small intestine and ceca length. Small intestinal length significantly decreased in broilers supplemented with milk and molasses kefir(P < 0.05). Molasses kefir supplementation significantly(P < 0.05) increased antibody titer against SRBC at 31 days of age but other immune related parameters were not statistically different among treatments. Biochemical parameters including serum protein, albumin, and triglyceride concentrations were not statistically(P> 0.05) influenced. Broilers supplemented with molasses kefir, had a significantly lower concentration of serum total cholesterol, low density lipoprotein cholesterol and elevated high density lipoprotein cholesterol at 42 days of age(P < 0.05). In conclusion, the results indicated that inclusion of 2% milk kefir in drinking water would improve growth performance of broiler chickens.
文摘In this paper,we study a multi-strain SEIR epidemic model with both bilinear and nonmonotone incidence functions.Under biologically motivated assumptions,we show that the model has two basic reproduction numbers that we noted R0,1 and R0,2;and four equilibrium points.Using the Lyapunov method,we prove that if R0,1 and R0,2 are less than one then the disease-free equilibrium is Globally Asymptotically Stable,thus the disease will be eradicated.However,if one of the two basic reproduction numbers is greater than one,then the strain that persists is that with the larger basic reproduction number.And finally if both of the two basic reproduction numbers are equal or greater than one then the total endemic equilibrium is globally asymptotically stable.A numerical simulation is also presented to illustrate the influence of the psychological effect,of people to infection,on the spread of the disease in the population.This simulation can be used to determine the status of different diseases in a region using the corresponding data and infectious disease parameters.
文摘A vaccine breakthrough infection and a rebound infection cases of COVID-19 are studied and analyzed for the ten U.S.Department of Health and Human Services(HHS)regions and the United States as a nation in this work.An innovative multi-strain susceptible-vacci-nated-exposed-asymptomatic-symptomatic-recovered(SVEAIR)epidemic model is devel-oped for this purpose for a population assumed to be susceptible to n-different variants of the disease,and those who are vaccinated and recovered from a specific strain k(kn)of the disease are immune to present strain and its predecessors j=1,2,…,k,but can still be infected by newer emerging strains j=k+1,k+2,…,n.The model is used to estimate epidemiological parameters,namely,the latent and infectious periods,the transmission rates,vaccination rates,recovery rates for each of the Delta B.1.617.2,Omicron B.1.1.529,and lineages BA.2,BA.2.12.1,BA.4,BA.5,BA.1.1,BA.4.6,and BA.5.2.6 for the United States and for each of the ten HHS regions.The transmission rate is estimated for both the asymptomatic and symptomatic cases.The effect of vaccines on each strain is analyzed.Condition that guarantees existence of an endemic with certain number of strains is derived and used to describe the endemic state of the population.
