Plant growth and development exhibit plasticity, and plants can adapt to environmental changes and stress. Various phytohormones interact synergistically or antagonistically to regulate these responses. Melatonin and indole-3-acetic acid (IAA) are widespread across plant kingdom. Melatonin, an important member of the neuroendocrine immune regulatory network, can confer autoimmunity and protect against viral invasion. Melatonin functions as a plant growth regulator and biostimulant, with an important role in enhancing plant stress tolerance. IAA has a highly complex stress response mechanism, which participates in a series of stress induced physiological changes. This article reviews studies on the signaling pathways of melatonin and IAA, focusing on specific regulatory mechanisms. We discuss how these hormones coordinate plant growth and development and stress responses. Furthermore, the interactions between melatonin and IAA and their upstream and downstream transcriptional regulation are discussed from the perspective of modulating plant development and stress adaptation. The reviewed studies suggest that, at low concentrations, melatonin promotes IAA synthesis, whereas at high levels it reduces IAA levels. Similarly to IAA, melatonin promotes plant growth and development. IAA suppresses the melatonin induced inhibition of germination. IAA signaling plays an important role in plant growth and development, whereas melatonin signaling plays an important role in stress responses.

The performance and reliability of multilayer coating systems are strongly influenced by thermal stresses. The present study develops an alternative analytical model to predict the thermal stresses in elastic multilayer coating systems. An exact closed-form solution is obtained which is independent of the number of coating layers. In addition, with the definition of the coordinate system, the closed-form solution is concisely formulated. Specific results are calculated for thermal stresses in HfO2/SiO2 multilayer optical coatings, and a finite element analysis is performed to confirm the analytical results. The two results agree fairly well with each other. Also, when the thicknesses of the coating layers are much less than the substrate thickness, the approximate solution is obtained based on the exact closed-form solution, and its accuracy is examined.

No abstract

No abstract

HfO 2 /SiO 2 high reflective optical coatings are widely used in high power laser applications because of their high laser damage resistance and appropriate spectral performance. The residual stresses strongly influence the performance and longevity of the optical coatings. Thermal stresses are the primary components of the residual stresses. In the present work, the distribution of thermal stresses in HfO 2 /SiO 2 high reflective optical coatings was investigated using two different computational methods: finite element method (FEM) and an analytical method based on force and moment balances and classical beam bending theory. The results by these two methods were compared and found to be in agreement with each other, demonstrating that these two methods are effective and accurate ways to predict the thermal stresses in HfO 2 /SiO 2 optical coatings. In addition, these two methods were also used to obtain the thermal stresses in HfO 2 /SiO 2 optical coatings with different layer number to investigate the effect of the layer number on the thermal stresses of the HfO 2 /SiO 2 optical coatings. The results show that with the increase of the layer number, the stresses in the substrate increase, while the stresses in the respective SiO 2 and HfO 2 layers decrease. Besides, it was also found that the radius of curvature of the coating system decreases as the layer number increases, leading to larger bending curvature in the system. HfO 2 /SiO 2 multilayer coatings thermal stresses analytical method finite element method