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Objective: This study aimed to explore the changes of polypeptides and free amino acids in Acetes chinensis before and after autolysis. Methods: The optimal pH and temperature of the endogenous protease of the A. chinensis were determined and the autolysis conditions were optimized. Then changes of a polypeptide, amino acid and molecular weight in the product before and after autolysis were studied under the optimal conditions. Results: The optimum temperature and pH of endogenous protease were 45 ℃ and 8.0 respectively. Under the optimal autolysis conditions of pH 8.0, temperature 40 ℃, and reaction time 4 h, the polypeptide concentration of A. chinensis surimi was 10.36 mg/mL. The content of total free amino acids, essential amino acids and hydrophobic amino acids increased, the proportion of bitter amino acids increased by （4.54±0.02）%, while the proportion of umami amino acids and sweet amino acids decreased by （3.46±0.02）% and （1.78±0.01）% respectively. The proportion of degradation products with molecular weight less than 1 000 Da increased from 70% to 87%. Conclusion: Autolysis technology can degrade the protein of A. chinensis and release small molecule peptides and amino acids.

When high-strength steel is heated to high temperatures and then cooled naturally, its ductility decreases. In earthquake-prone areas, it is necessary to evaluate the ultra-low cycle fatigue fracture (ULCF) behavior of high-strength steel structures after a fire if these structures are used continuously. However, the ULCF fracture model of high-strength steel subjected to high temperatures followed by natural cooling has not been deeply studied. In view of this, twelve notched, round bar specimens fabricated from Q460D steel and ER55-G welds were heated to 900 °C followed by natural cooling and then cyclic loading experiments and finite element analyses (FEA) were performed on these specimens. The fracture deformation obtained from the experiments was used in the FEA to calibrate the damage degradation parameter of a Cyclic Void Growth Model (CVGM) of Q460D steel and ER55-G welds under this condition. The calibrated values were 0.30 and 0.20, respectively. The calibrated CVGM was employed to predict the number of cycles and the force and displacement at the fracture moment of the notched round bar specimens. The predicted results aligned closely with the experimental results, indicating that CVGM is effective in predicting the fracture of Q460D steel and ER55-G welds following exposure to 900 °C and subsequent natural cooling. [ABSTRACT FROM AUTHOR]

Kernel independent component analysis (KICA), as a nonlinear extension monitoring method of independent component analysis (ICA), has attracted significant attention. To accomplish different monitoring tasks for nonlinear systems with non-Gaussian data distribution, many modified algorithms based on KICA have also been designed. However, most of the existing methods suffer from defects; for example, the computation time increases with the number of training samples and the models are insensitive to minor faults. Nevertheless, there is currently limited research on addressing these defects, which greatly limits their application in industrial processes. To fill these gaps, a novel reduced kernel independent component analysis (NRKICA) method is proposed to reduce the computation complexity and improve the ability of minor fault detection at the same time. In this approach, an important factor is defined to measure the ability of the samples to represent the properties of the system. In addition, then the top-n important observations are selected to build a data dictionary. To improve the sensitivity to minor faults, the I 2 and SPE statistics are redesigned by introducing information from past observations. Besides, the kernel parameter is optimized by the tabu search algorithm. The proposed method is applied to fault detection with a numerical example and the Tennessee Eastman process (TEP), and the experimental results verify the effectiveness and sensitivity of the proposed method. [ABSTRACT FROM AUTHOR]

Hulun Lake is the largest lake in northeastern China, and its basin is located in China and Mongolia. This research aims to analyze the dynamic changes in the water volume of Hulun Lake and to estimate the groundwater recharge of the lake during the past 60 years. Multi-source data were used, and water-level-data-interpolation extrapolation, water-balance equations, and other methods were applied. The proportion of the contribution of each component to the quantity of water in Hulun Lake during the last 60 years was accurately calculated. Evaporation loss was the main component in the water loss in Hulun Lake. In the last 60 years, the average annual runoff into the lake was about 1.202 billion m3, and it was the factor with the largest variation range and the leading factor affecting the changes in the quantity of water in Hulun Lake. There was groundwater recharge in Hulun Lake for a long period, and the average annual groundwater recharge was about 776 million m3 (excluding leakage). The contribution ratio of the river water, groundwater, and precipitation to the recharging of Hulun Lake was about 5:3:2. The changes in the quantity of water in Hulun Lake are affected by climate change and human activities in China and Mongolia, especially those in Mongolia. [ABSTRACT FROM AUTHOR]

A stress‐induced failure study on a high‐temperature air‐stable ceramic composite solar selective absorber (SSA) based on a W–SiO2 system is reported. The as‐prepared SSA exhibits excellent spectral and structural stability after annealing in air at 500 °C for 36 h, proving its thermal stability against air corrosion. However, once the temperature is elevated to 600 °C, optical performance degradation and coating cracking happens. The X‐ray diffraction (XRD) patterns reveal that an O‐induced phase transition process from α‐W to β‐W occurs at the interface between the W IR reflector and W–SiO2 layer during deposition. The phase transition induces immense internal stress, which becomes the incentive of crack generation. Further increasing the annealing temperature, drastic structural changes of oxidized W become the driving force for crack propagation and hole expansion, leading to a failure analogous to a volcanic eruption. To improve the temperature limit of coating, a Ni–SiO2 stress buffer layer is introduced and successfully reduces the internal stress through Ni atom substitution for W atoms. Therefore, the optimized SSA keeps stable at 600 °C and the cracking temperature increases to 650 °C. These results suggest that the W–SiO2‐based SSA is a good candidate for air‐stable high‐temperature solar thermal conversion. [ABSTRACT FROM AUTHOR]