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To achieve the high-value utilization of squid skin obtained from squid processing, this study utilized an enzymatic approach to prepare protein peptides. The enzymatic hydrolysis parameters were optimized using single factor and response surface tests, with the concentration of peptide and trichloroacetic acid-nitrogen soluble index (TCA-NSI) serving as evaluation criteria. The amino acid composition, molecular weight distribution, peptide sequence, antioxidant activity, and in vitro simulated digestive properties of the prepared protein peptides were also thoroughly characterized. The results showed that the optimal conditions for enzymatic hydrolysis were as follows: Enzymatic temperature of 43.50 ℃, enzymatic time of 100 minutes, enzymatic pH of 7.50, trypsin to alkaline protease ratio of 2:1, and enzyme dosage of 4000 U/g. Under these specified conditions, the TCA-NSI achieved a value of 89.02%±0.66%. The prepared protein peptides exhibited a well-balanced amino acid composition, with an essential amino acid index (EAAI) value of 0.90. Furthermore, the prepared protein peptides encompassed a total of 43 polypeptide sequences, with 38 of these segments exhibiting molecular weights below 1800 Da. The IC50 values for scavenging DPPH radical, ABTS+ radical, and hydroxyl radical were determined to be 0.61, 0.28 and 1.95 mg/mL, respectively. Notably, the antioxidant activity remained favorable even after undergoing simulated gastrointestinal digestion in vitro. These findings serve to establish a solid theoretical basis for the advancement and exploitation of byproducts derived from squid processing, as well as their subsequent value-added utilization.

To construct a heterotrophic axenic system of Chlorella sorokiniana FZU60, the symbiotic bacteria were isolated and identified, and the effects of eight common antibiotics (cefotaxime, kanamycin, neomycin, ampicillin, streptomycin, tetracycline, chloramphenicol, and erythromycin) on the cell growth of symbiotic bacteria and C. sorokiniana FZU60 were investigated. Results showed that the main symbiotic bacteria were Bacillus (78.76%) and Methylobacterium (3.14%). Besides, 10 mg/L cefotaxime, 10 mg/L tetracycline, 100 mg/L kanamycin, and 100 mg/L erythromycin showed excellent inhibitory effect on these two symbiotic bacteria but no obvious effect on the cell growth of C. sorokiniana FZU60. Based on the above-mentioned results, the inhibition effect of different antibiotic combinations on symbiotic bacteria of C. sorokiniana FZU60 was further investigated. It was found that the heterotrophic axenic system could be successfully constructed by using the combination of 10 mg/L cefotaxime, 10 mg/L tetracycline, and 100 mg/L kanamycin. Moreover, C. sorokiniana FZU60 could maintain stable and axenic growth after three generations. The experimental results would provide theoretical reference and experimental basis for the preparation of axenic microalgal seed for high-cell-density heterotrophic cultivation of C. sorokiniana.

A rechargeable unmanned aerial vehicle (UAV) aided wireless sensor network was considered, which consists of multiple ground terminals with a large amount of time-sensitive data to be collected.Due to the limited battery capacity, the UAV cannot collect the data from all terminals through a single flight mission, and it needs to return to the charging pile to replenish its flight energy several times during the whole mission.The optimization of the terminal scheduling, trajectory, flight speed and transmission rate for the UAV was studied to maximize the number of terminals whose data had been collected within the data lifetime limit.Due to the variable coupling and the existence of discrete binary scheduling variables, the considered optimization problem is difficult to solve.To tackle such a difficulty, an efficient algorithm was proposed based on the stochastic optimization and the feature engineering.Specifically, the flight hover communication protocol was introduced to simplify the UAV flight process.And then a terminal scheduling algorithm was innovatively proposed with the influence factor and the stochastic preference, which extracted the features that affect the service time of the UAV, optimized the weights of the features, and further simplified the optimization problem into multiple subproblems.The subproblems were then solved by using the block coordinate descent and successive convex approximation techniques.Simulation results show that the proposed optimization algorithm achieves significant performance gains over several benchmark schemes in the scenarios with different data lifetime requirements and different numbers of ground terminals.

Two intelligent reflecting surfaces (IRS) was applied to ensure the physical layer security of the information transmission in a simultaneous wireless information and power transfer (SWIPT) system, where a multi-antenna base station (BS) simultaneously transmits information and energy to multiple single-antenna information receivers (IR) and energy receivers (ER) and the ERs are regarded as potential information eavesdroppers.The system deploys two IRSs to ensure the security of information transmission while meeting the requirements of energy transmission.Due to the inter-IRS signal reflection, the variables of the considered optimization problem are highly coupled, thus the problem is difficult to solve.To tackle this difficulty, an algorithm based on the alternating optimization, semidefinite relaxation, and successive convex approximation methods was proposed to obtain a suboptimal solution to the problem.Simulation results show that the proposed algorithm can significantly increase the total rate of the IRs and guarantee the security of the information transmission and the requirement of energy transmission, as compared to some existing benchmark schemes.

In this study, chitosan was used to enhance the photodynamic antibacterial effect of curcumin through ionic interactions, and the antibacterial mechanism of this coating against Staphylococcus aureus at the cellular level was clarified from the aspects of morphological characteristics, cell membrane function, energy metabolism, and DNA structure. The results showed that chitosan significantly improve the antibacterial effect. The number of S. aureus decreased by 6.89 (lg(CFU/mL)) after the coating solution containing 15 mg/L curcumin was exposed to 420 nm blue light for 5 min. Curcumin concentration and illumination time were the major factors affecting the antibacterial effect of this technique. The photodynamic inactivation treatment produced highly oxidizing reactive oxygen species (ROS), damaging the cell membrane and increasing membrane permeability, thus leading to the leakage of cell contents and cell shrinkage. It also led to an increase in intracellular ROS levels, which disrupted the structure of endogenous enzymes to trigger the breakdown of the bacterial defense system and the oxidative decomposition of macromolecules such as DNA and proteins, eventually causing the death of S. aureus. Therefore, chitosan/curcumin photodynamic coating has application potential in controlling foodborne pollution of S. aureus.

To study the distribution law of coal spontaneous combustion zone in goaf of two intake and one return ventilation working face, the oxygen concentration under different working conditions during the mining of the 8301 working face of Tashan Coal Mine was simulated, the danger zone of spontaneous combustion of coal was determined and corresponding fire prevention measures were proposed. The spontaneous combustion danger zone of coal in the goaf of two intake and one return ventilation working face is large, and the spontaneous combustion zone reaches 96 m when the mining distance is 150 m; nitrogen injection can greatly change the distribution of spontaneous combustion zones and reduce the spontaneous combustion of coal in the goaf. For the two intake and one return ventilation working face, nitrogen injection should be considered on both sides of the goaf; increasing air volume allows the boundary of the spontaneous combustion zone to extend deep into the goaf and increase the distance of the front end from the working face.

For the special case above the working face of Tashan Coal Mine, the numerical simulation software was used to study the distribution of oxygen molar concentration in the goaf under different mining distances and different amounts of nitrogen injection and determine the coal spontaneous combustion danger zone in the goaf. Results show that long-distance extraction of gas makes the coal spontaneous combustion danger zone larger. As the mining distance increases, the spontaneous combustion danger zone gradually widens. When the mining distance is 50 m, the rate of widening the spontaneous combustion zone suddenly becomes larger. The ratio of the width of the spontaneous combustion zone on the inlet side to the length of mining distance is 180% higher than that of the mining distance of 30 m to 50 m, and the return side is 140% higher, causing larger risk of spontaneous combustion of coal; nitrogen injection can greatly reduce the coal spontaneous combustion danger zone in the goaf.