Hexanal contributes significantly to meat flavor.The aim of this study was to identify the metabolic pathways of hexanal formation in chicken meat.We found 32 metabolites associated with hexanal content in chicken mea...Hexanal contributes significantly to meat flavor.The aim of this study was to identify the metabolic pathways of hexanal formation in chicken meat.We found 32 metabolites associated with hexanal content in chicken meat,mainly including fatty acids(linoleic acid,etc.,positive correlation)and some amino acids(L-proline,etc.,negative correlation).A comparative analysis of the expression of these 32 metabolites between two groups of chickens with high-and low-hexanal content revealed that L-proline and phenylacetaldehyde were downregulated,while ADP-ribose and 4-methylphenol were upregulated in the high-hexanal content chickens.It was also found that the increase of ADP-ribose induced the conversion of L-proline to other amino acids,such as arginine,through a process likely involving the pyrimidine metabolism pathway,leading to a reduction in proline content,which in turn abolished the inhibitory effect of proline on hexanal and enhanced the formation of hexanal.These findings confirm the effect of linoleic acid on hexanal content,and also reveal a negative regulatory effect of proline on the production of hexanal and its elimination mechanism in chicken meat.展开更多
<div style="text-align:justify;"> Due to the influence of processing technology and environmental factors, there are errors in attitude measurement with the three-axis magnetometer, and the change of p...<div style="text-align:justify;"> Due to the influence of processing technology and environmental factors, there are errors in attitude measurement with the three-axis magnetometer, and the change of parameters during the operation of the magnetometer in orbit will have a great impact on the measurement accuracy. This paper studies the calibration method of magnetometer based on BP neural network, which reduces the influence of model error on calibration accuracy. Firstly, the error model of the magnetometer and the structural characteristics of the BP neural network are analyzed. Secondly, the number of hidden layers and hidden nodes is optimized. To avoid the problem of slow convergence and low accuracy of basic BP algorithm, this paper uses the Levenberg Marquardt backpropagation training method to improve the training speed and prediction accuracy and realizes the on-orbit calibration of magnetometer through online training of the neural network. Finally, the effectiveness of the method is verified by numerical simulation. The results show that the neural network designed in this paper can effectively reduce the measurement error of magnetometer, while the online training can effectively reduce the error caused by the change of magnetometer parameters, and reduce the measurement error of magnetometer to less than 10 nT. </div>展开更多
基金funded by grants from the State Key Laboratory of Animal Nutrition(2004DA125184G2109)Basic Research from Chinese Academy of Agricultural Sciences(Y2019XK06)+1 种基金the Agricultural Science and Technology Innovation Program(ASTIP-IAS04)the Earmarked Fund for Modern Agro-Industry Technology Research System(CARS-41)。
文摘Hexanal contributes significantly to meat flavor.The aim of this study was to identify the metabolic pathways of hexanal formation in chicken meat.We found 32 metabolites associated with hexanal content in chicken meat,mainly including fatty acids(linoleic acid,etc.,positive correlation)and some amino acids(L-proline,etc.,negative correlation).A comparative analysis of the expression of these 32 metabolites between two groups of chickens with high-and low-hexanal content revealed that L-proline and phenylacetaldehyde were downregulated,while ADP-ribose and 4-methylphenol were upregulated in the high-hexanal content chickens.It was also found that the increase of ADP-ribose induced the conversion of L-proline to other amino acids,such as arginine,through a process likely involving the pyrimidine metabolism pathway,leading to a reduction in proline content,which in turn abolished the inhibitory effect of proline on hexanal and enhanced the formation of hexanal.These findings confirm the effect of linoleic acid on hexanal content,and also reveal a negative regulatory effect of proline on the production of hexanal and its elimination mechanism in chicken meat.
文摘<div style="text-align:justify;"> Due to the influence of processing technology and environmental factors, there are errors in attitude measurement with the three-axis magnetometer, and the change of parameters during the operation of the magnetometer in orbit will have a great impact on the measurement accuracy. This paper studies the calibration method of magnetometer based on BP neural network, which reduces the influence of model error on calibration accuracy. Firstly, the error model of the magnetometer and the structural characteristics of the BP neural network are analyzed. Secondly, the number of hidden layers and hidden nodes is optimized. To avoid the problem of slow convergence and low accuracy of basic BP algorithm, this paper uses the Levenberg Marquardt backpropagation training method to improve the training speed and prediction accuracy and realizes the on-orbit calibration of magnetometer through online training of the neural network. Finally, the effectiveness of the method is verified by numerical simulation. The results show that the neural network designed in this paper can effectively reduce the measurement error of magnetometer, while the online training can effectively reduce the error caused by the change of magnetometer parameters, and reduce the measurement error of magnetometer to less than 10 nT. </div>
