Late embryogenesis abundant (LEA) proteins are a family of small highly hydrophilic proteins that accumulate at the onset of seed desiccation and in response to adverse conditions such as drought, salinity, low temperature, or water deficit. In previous studies, we demonstrated that ZmLEA3 could enhance the transgenic tobacco tolerance to osmotic and oxidative stresses. Here, we demonstrated that the transcription of ZmLEA3 in the maize stems could be significantly induced by low temperature and osmotic stresses and by treatment with abscisic acid (ABA) and H2O2. Further study indicated that ZmLEA3 is a single copy gene in the maize genome. The ZmLEA3 protein could protect lactate dehydrogenase (LDH) activity at low temperatures. The overexpression of ZmLEA3 conferred tolerance to low-temperature stress to transgenic tobacco, yeast (GS115) and E. coli (BL21).
The preparation and characteristics of rigid polyurethane foams (RPUFs) based on recycled polyol obtained by glycolysis of waste RPUF scraps from end-of-life refrigerators were investigated. To deactivate the amine adducts derived from isocyanates, the recycled product obtained after depolymerization was chemically modified via addition polymerization of propylene oxide. Two kinds of recycled polyols with different hydroxyl values and viscosity were blended with conventional virgin polyether polyol to prepare the RPUFs. The effects of the recycled polyols on the physical properties of RPUFs such as cell structures, compressive strength, thermal conductivity, and limiting oxygen index were discussed. It was found that the RPUFs from recycled polyols showed superior compressive strength, thermal insulation property, and selfextinguishing property compared with conventional control foam. The results of this study reveal that the recycled polyols could be used as feedstock for RPUFs with superior performance.
A non-orthogonal elastoplastic model for clay is proposed by combining the non-orthogonal plastic flow rule with the critical state concept and presented from the perspective of the magnitude and direction of the plastic strain increment. The magnitude is obtained based on the improved elliptical yield function and the plastic volumetric strain dependent hardening parameter. The direction is determined by applying the non-orthogonal plastic flow rule with the Riemann-Liouville fractional derivative to the yield function without the necessity of additional plastic potential function. The presented approach gives rise to a simple model with five parameters. All parameters have clear physical meaning and can be easily identified by triaxial tests. The model performance is shown by analyzing the evolution process of the yield surface, the hardening rule and the plastic flow direction.The capability of the proposed model to capture the mechanical behaviours of clay with different stiffness is also confirmed by predicting test results from the literature.
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