Preparation and in Vitro Digestive Analysis of Casein-Derived Peptide-Zinc Chelates

In this study, casein peptides were obtained by alcalase hydrolyzation and Lactobacilus fermentation to prepare the casein peptide-zinc chelates, which are a kind of efficient and well-absorbed zinc supplement. The structure of casein peptide-zinc chelates was characterized by spectroscopic instruments. The digestive stability and safety were also assayed using in vitro digestive model and Caco-2 cell experiment. The results indicated that the optimal conditions for preparing casein peptides were as follows: Volume of alcalase was 0.3% (w/v), pH of reaction system was 9.0, Lactobacilus fermentation time was 12 h. Under this condition, the peptide content was 142.39±0.95 mg/g, and the zinc chelation rate was 31.41%±0.97%. The chelation with zinc destroyed the structure of casein peptides leading to a loose surface structure. Spectroscopic analysis showed that Zn2+ can bind to the reactive groups on casein peptides, with the chelating sites being carboxyl oxygen, hydroxyl oxygen and amino groups. The results of in vitro digestion showed that casein peptide-zinc chelates possessed better solubility than that of zinc sulfate. After gastrointestinal digestion, the DPPH and ABTS+ scavenging ability of casein peptide-zinc chelates increased by 26.19%±3.30% and 71.96%±7.06%, respectively. However, the ferric ion reducing power of the casein peptide-zinc chelates decreased by 36.26%±2.80%. At the same time, the β-turn and random coil content of the casein peptide-zinc chelate decreases during digestion, the β-sheet structure increases and Zn2+ play a role in maintaining the peptide structure. Furthermore, the cytotoxicity test indicated that casein peptide-zinc chelates gastrointestinal digest were toxic to Caco-2 cells when the concentration exceeded 0.4 mg/mL. Finally, 15 and 13 dairy-derived peptides were identified from casein hydrolysate and casein peptide-zinc chelates, respectively, using mass spectrometry. These results will provide scientific evidence for the development and application of efficient casein peptide-zinc chelates

Experimental Evidence of Thermal Effects in Multiphase Ceramic Specimens Subjected to Cyclic Loading

International audienceThe aim of this work is to observe and to analyze various phenomena that exist in a multiphase ceramic material subjected to cyclic compressive loads. An infrared camera is used for this purpose. The material under study is an andalusite-based low-cement castable, which exhibits a pre-existing diffused damage (microcracks and debonded interfaces) before mechanical testing. The temperature variation in the specimen during the tests is investigated both at a macroscopic scale and a mesoscopic scale. In the first case, the material compaction, the thermoelastic coupling and the temperature increase due to mechanical dissipation are clearly evidenced. In the second case, local temperature variations related to microcracks are observed. The technique used and the results obtained are described and discussed in the paper

Landslide Deformation Extraction from Terrestrial Laser Scanning Data with Weighted Least Squares Regularization Iteration Solution

The extraction of landslide deformation using terrestrial laser scanning (TLS) has many important applications. The landslide deformation can be extracted based on a digital terrain model (DTM). However, such methods usually suffer from the ill-posed problem of a multiplicative error model as illustrated in previous studies. Moreover, the edge drift of commonly used spherical targets for point cloud registration (PCR) is ignored in the existing method, which will result in the unstable precision of the PCR. In response to these problems, we propose a method for extracting landslide deformations from TLS data. To archive the PCR of different period point clouds, a new triangular pyramid target is designed to eliminate the edge drift. If a fixed target is inconvenient, we also propose a PCR method based on total station orientation. Then, the use of the Tikhonov regularization method to derive the weighted least squares regularization solution is presented. Finally, the landslide deformation is extracted by DTM deference. The experiments are conducted on two datasets with more than 1.5 billion points. The first dataset takes Lashagou NO. 3 landslide in Gansu Province, China, as the research object; the point cloud data were collected on 26 February 2021 and 3 May 2021. The registration accuracy was 0.003 m based on the permanent triangular pyramid target and 0.005 m based on the total station orientation. The landslide deforms within 3 cm due to the ablation of the frozen soil. The second dataset is TLS data from the Lihua landslide in Chongqing, China, collected on 20 April 2021 and 1 May 2021. The overall deformation of the Lihua landslide is small, with a maximum value of 0.011 m. The result shows that the proposed method achieves a better performance than previous sphere-based registration and that the weighted least square regularization iterative solution can effectively reduce the ill-condition of the model

Landslide Deformation Extraction from Terrestrial Laser Scanning Data with Weighted Least Squares Regularization Iteration Solution

The extraction of landslide deformation using terrestrial laser scanning (TLS) has many important applications. The landslide deformation can be extracted based on a digital terrain model (DTM). However, such methods usually suffer from the ill-posed problem of a multiplicative error model as illustrated in previous studies. Moreover, the edge drift of commonly used spherical targets for point cloud registration (PCR) is ignored in the existing method, which will result in the unstable precision of the PCR. In response to these problems, we propose a method for extracting landslide deformations from TLS data. To archive the PCR of different period point clouds, a new triangular pyramid target is designed to eliminate the edge drift. If a fixed target is inconvenient, we also propose a PCR method based on total station orientation. Then, the use of the Tikhonov regularization method to derive the weighted least squares regularization solution is presented. Finally, the landslide deformation is extracted by DTM deference. The experiments are conducted on two datasets with more than 1.5 billion points. The first dataset takes Lashagou NO. 3 landslide in Gansu Province, China, as the research object; the point cloud data were collected on 26 February 2021 and 3 May 2021. The registration accuracy was 0.003 m based on the permanent triangular pyramid target and 0.005 m based on the total station orientation. The landslide deforms within 3 cm due to the ablation of the frozen soil. The second dataset is TLS data from the Lihua landslide in Chongqing, China, collected on 20 April 2021 and 1 May 2021. The overall deformation of the Lihua landslide is small, with a maximum value of 0.011 m. The result shows that the proposed method achieves a better performance than previous sphere-based registration and that the weighted least square regularization iterative solution can effectively reduce the ill-condition of the model

Challenges and Opportunities for the Blue Perovskite Quantum Dot Light-Emitting Diodes

Perovskite quantum dots (PQDs), as the promising materials for the blue light-emitting diodes (LEDs), own huge advantages as ultra-high color purity, flexibility and whole-spectrum tunability. Through dimensional and compositional engineering, PQD-LEDs have shown superiority in deep-blue light emission. However, compared with the fast development of red and green PeLEDs, the electroluminescent performance of PQD-LEDs has faced more obstacles. In this review, we aim to explore and state the uniqueness and the possible solutions for the bottleneck problems of the PQD-LEDs

Challenges and Opportunities for the Blue Perovskite Quantum Dot Light-Emitting Diodes

Perovskite quantum dots (PQDs), as the promising materials for the blue light-emitting diodes (LEDs), own huge advantages as ultra-high color purity, flexibility and whole-spectrum tunability. Through dimensional and compositional engineering, PQD-LEDs have shown superiority in deep-blue light emission. However, compared with the fast development of red and green PeLEDs, the electroluminescent performance of PQD-LEDs has faced more obstacles. In this review, we aim to explore and state the uniqueness and the possible solutions for the bottleneck problems of the PQD-LEDs