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At present, most hydrogels used in the food industry are natural polymers, with poor mechanical properties and high moisture content, which is easy to be contaminated by microorganisms, making it difficult to meet the use needs. In recent years, new composite hydrogels loaded with active substances prepared from natural and synthetic polymers or modified natural polymers have been increasingly used in the food field.. Starting from the preparation method of composite hydrogels, this paper introduces its application status in food packaging materials, fat and starch substitution, bioactive molecule delivery, rapid detection of microorganisms, and prospects the development trend of composite hydrogels in the food industry.

Current recommendation algorithms based on hashing technology commonly uses Hamming distance to indicate the similarity between user hash code and item hash code,while it ignores the potential difference information of each bit dimension.Therefore,this paper proposes a differential Hamming distance,which by calculating the dissimilarity between hash codes to assign bit weights.This paper designs a variational recommendation model for dissimilarity Hamming distance.The model is divided into a user hash component and an item hash component,which are connected by variational autoencoder structure.The model uses encoder to generate hash codes for user and items.In order to improve the robustness of the hash codes,we apply a Gaussian noise to both user and item hash coeds.Besides,the user and item hash codes are optimized by differential Hamming distance to maximize the ability of the model to reconstruct user-item scores.Experiments on benchmark datasets demonstrate that the proposed algorithm VDHR improves 3.9% in NDCG and 4.7% in MRR compared to the state-of-the-art hash recommendation algorithm under the premise of constant computational cost.

In order to promote the application of low - cost and high - performance chromium - free ZnAl coating in the protection of NdFeB permanent magnet, the effects of different pretreatment processes (alkali washing, pickling, sandblasting, sandblasting + pickling) on the adhesive strength and corrosion resistance of chromium - free ZnAl coating prepared on the surface of NdFeB permanent magnet were studied using SEM and TR300 profilometer. Results showed that both sandblasting and sandblasting + pickling (5 s) could significantly increase the adhesive strength between the chromium - free ZnAl coating and the NdFeB substrate; the ZnAl coating prepared after an alkali washing had the strongest corrosion resistance to the ammonium nitrate immersion (up to 230 min). The pretreatment processes of sandblasting and sandblasting + acid pickling (5 s) could increase the surface roughness of the substrate and enlarge the contact area of ZnAl coating solution with the substrate surface to enhance the adhesive strength, but the corrosion resistance of the coating was far lower than that of the coating treated with alkali washing due to the damage to the substrate surface caused by the high - speed impact of sand particles during sandblasting. After the substrate was pretreated with pickling (50 s), the corrosion resistance of the coating was greatly reduced. Therefore, as a low - damage and environmental friendly pretreatment process, alkali washing was the best pretreatment for ZnAl coating prepared on sintered NdFeB surface.

The prospect of α-Ga2O3 in optical and electrical devices application is fascinating. In order to obtain better performance, Ge and F elements with similar electronegativity and atomic size are selected as dopants. Based on density functional theory (DFT), we systematically research the electronic structure and optical properties of doped α-Ga2O3 by GGA+U calculation method. The results show that Ge atoms and F atoms are effective n-type dopants. For Ge-doped α-Ga2O3, it is probably obtained under O-poor conditions. However, for F-doped α-Ga2O3, it is probably obtained under O-rich conditions. The doping system of F element is more stable due to the lower formation energy. In this investigation, it is found that two kinds of doping can reduce the α-Ga2O3 band gap and improve the conductivity. What is more, it is observed that the absorption edge after doping has a blue shift and causes certain absorption effect on the visible region. Through the whole scale of comparison, Ge doping is more suitable for the application of transmittance materials, yet F doping is more appropriate for the application of deep ultraviolet devices. We expect that our research can provide guidance and reference for preparation of α-Ga2O3 thin films and photoelectric devices. [ABSTRACT FROM AUTHOR]