Soil microbial communities are key factors in maintaining ecosystem multifunctionality(EMF).However,the distribution patterns of bacterial diversity and how the different bacterial taxa and their diversity dimensions ...Soil microbial communities are key factors in maintaining ecosystem multifunctionality(EMF).However,the distribution patterns of bacterial diversity and how the different bacterial taxa and their diversity dimensions affect EMF remain largely unknown.Here,we investigated variation in three measures of diversity(alpha diversity,community composition and network complexity)among rare,intermediate,and abundant taxa across a latitudinal gradient spanning five forest plots in Yunnan Province,China and examined their contributions on EMF.We aimed to characterize the diversity distributions of bacterial groups across latitudes and to assess the differences in the mechanisms underlying their contributions to EMF.We found that multifaceted diversity(i.e.,diversity assessed by the three different metrics)of rare,intermediate,and abundant bacteria generally decreased with increasing latitude.More importantly,we found that rare bacterial taxa tended to be more diverse,but they contributed less to EMF than intermediate or abundant bacteria.Among the three dimensions of diversity we assessed,only community composition significantly affected EMF across all locations,while alpha diversity had a negative effect,and network complexity showed no significant impact.Our study further emphasizes the importance of intermediate and abundant bacterial taxa as well as community composition to EMF and provides a theoretical basis for investigating the mechanisms by which belowground microorganisms drive EMF along a latitudinal gradient.展开更多
During the whole service lifetime of aircraft structures with composite materials,impacts are inevitable and can usually cause severe but barely visible damages.Since the occurrences of impact are random and unpredict...During the whole service lifetime of aircraft structures with composite materials,impacts are inevitable and can usually cause severe but barely visible damages.Since the occurrences of impact are random and unpredictable,it is a hotspot direction to develop an online impact monitoring system that can meet strict limitations of aerospace applications including small size,light weight,and low power consumption.Piezoelectric(PZT)sensor,being able to generate impact response signals with no external power and cover a large-scale structure with only a small amount of them,is a promising choice.Meanwhile,for real systems,networks with multiple nodes are normally required to monitor large-scale structures in a global way to identify any impact localization confliction,yet the existing studies are mostly evaluated with single nodes instead of networks.Therefore,in this paper,based on a new low-power node designed,a Bluetooth-based digital impact monitoring PZT sensor network is proposed for the first time with its global confliction-solving impact localization method.Evaluations of the system as a network are researched and analyzed on a complex real aircraft wing box for a global confliction-solving impact localization,showing a satisfying high accuracy.展开更多
Measuring the complex permittivity of ultrathin,flexible materials with a high loss tangent poses a substantial challenge with precision using conventional methods,and verifying the accuracy of test results remains di...Measuring the complex permittivity of ultrathin,flexible materials with a high loss tangent poses a substantial challenge with precision using conventional methods,and verifying the accuracy of test results remains difficult.In this study,we introduce a methodology based on a back-propagation artificial neural network(ANN)to extract the complex permittivity of paper-based composites(PBCs).PBCs are ultrathin and flexible materials exhibiting considerable complex permittivity and dielectric loss tangent.Given the absence of mature measurement methods for PBCs and a lack of sufficient data for ANN training,a mapping relationship is initially established between the complex permittivity of honeycomb-structured microwave-absorbing materials(HMAMs,composed of PBCs)and that of PBCs using simulated data.Leveraging the ANN model,the complex permittivity of PBCs can be extracted from that of HMAMs obtained using standard measurement.Subsequently,two published methods are cited to illustrate the accuracy and advancement of the results obtained using the proposed approach.Additionally,specific error analysis is conducted,attributing discrepancies to the conductivity of PBCs,the homogenization of HMAMs,and differences between the simulation model and actual objects.Finally,the proposed method is applied to optimize the cell length parameters of HMAMs for enhanced absorption performance.The conclusion discusses further improvements and areas for extended research.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
基金supported by the Fundamental Research Funds of Chinese Academy of Forestry(Nos.CAFYBB2022SY037,CAFYBB2021ZA002 and CAFYBB2022QC002)the Basic Research Foundation of Yunnan Province(Grant No.202201AT070264).
文摘Soil microbial communities are key factors in maintaining ecosystem multifunctionality(EMF).However,the distribution patterns of bacterial diversity and how the different bacterial taxa and their diversity dimensions affect EMF remain largely unknown.Here,we investigated variation in three measures of diversity(alpha diversity,community composition and network complexity)among rare,intermediate,and abundant taxa across a latitudinal gradient spanning five forest plots in Yunnan Province,China and examined their contributions on EMF.We aimed to characterize the diversity distributions of bacterial groups across latitudes and to assess the differences in the mechanisms underlying their contributions to EMF.We found that multifaceted diversity(i.e.,diversity assessed by the three different metrics)of rare,intermediate,and abundant bacteria generally decreased with increasing latitude.More importantly,we found that rare bacterial taxa tended to be more diverse,but they contributed less to EMF than intermediate or abundant bacteria.Among the three dimensions of diversity we assessed,only community composition significantly affected EMF across all locations,while alpha diversity had a negative effect,and network complexity showed no significant impact.Our study further emphasizes the importance of intermediate and abundant bacterial taxa as well as community composition to EMF and provides a theoretical basis for investigating the mechanisms by which belowground microorganisms drive EMF along a latitudinal gradient.
基金supported by the National Natural Science Foundation of China(Nos.51921003,51975292 and 52275153)the Outstanding Youth Foundation of Jiangsu Province of China(No.BK20211519)+2 种基金the Research Fund of State Key Laboratory of Mechanics and Control of Mechanical Structures,China(Nanjing University of Aeronautics and Astronautics,No.MCMS-I-0521K01)the Fund of Prospective Layout of Scientific Research for Nanjing University of Aeronautics and Astronautics,Chinathe Priority Academic Program Development of Jiangsu Higher Education Institutions,China。
文摘During the whole service lifetime of aircraft structures with composite materials,impacts are inevitable and can usually cause severe but barely visible damages.Since the occurrences of impact are random and unpredictable,it is a hotspot direction to develop an online impact monitoring system that can meet strict limitations of aerospace applications including small size,light weight,and low power consumption.Piezoelectric(PZT)sensor,being able to generate impact response signals with no external power and cover a large-scale structure with only a small amount of them,is a promising choice.Meanwhile,for real systems,networks with multiple nodes are normally required to monitor large-scale structures in a global way to identify any impact localization confliction,yet the existing studies are mostly evaluated with single nodes instead of networks.Therefore,in this paper,based on a new low-power node designed,a Bluetooth-based digital impact monitoring PZT sensor network is proposed for the first time with its global confliction-solving impact localization method.Evaluations of the system as a network are researched and analyzed on a complex real aircraft wing box for a global confliction-solving impact localization,showing a satisfying high accuracy.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFB3700104).
文摘Measuring the complex permittivity of ultrathin,flexible materials with a high loss tangent poses a substantial challenge with precision using conventional methods,and verifying the accuracy of test results remains difficult.In this study,we introduce a methodology based on a back-propagation artificial neural network(ANN)to extract the complex permittivity of paper-based composites(PBCs).PBCs are ultrathin and flexible materials exhibiting considerable complex permittivity and dielectric loss tangent.Given the absence of mature measurement methods for PBCs and a lack of sufficient data for ANN training,a mapping relationship is initially established between the complex permittivity of honeycomb-structured microwave-absorbing materials(HMAMs,composed of PBCs)and that of PBCs using simulated data.Leveraging the ANN model,the complex permittivity of PBCs can be extracted from that of HMAMs obtained using standard measurement.Subsequently,two published methods are cited to illustrate the accuracy and advancement of the results obtained using the proposed approach.Additionally,specific error analysis is conducted,attributing discrepancies to the conductivity of PBCs,the homogenization of HMAMs,and differences between the simulation model and actual objects.Finally,the proposed method is applied to optimize the cell length parameters of HMAMs for enhanced absorption performance.The conclusion discusses further improvements and areas for extended research.
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.
