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The dynamic compressive mechanical performance of coral aggregate concrete (CAC) has been studied by the servo‐controlled true triaxial testing machine (TAWZ‐5000/3000), the failure modes and the stress–strain curves were obtained under various loading conditions. The effect of strain rates and the constant lateral pressure on the strength, deformation capacity, and failure modes of CAC were analyzed according to the results obtained from the test. The results show that the lateral pressure significantly changes the failure mode while the strain rate only affects the degree. The strength and deformation capacity will improve with the increase of strain rate and lateral pressure, and the lateral pressure diminishes the strain rate effect on mechanical properties. A 5‐parameter empirical dynamic failure criterion was established based on the William‐Warnke criterion. Finally, a 2‐stage dynamic multiaxial compressive constitutive model obeying the Weibull and Lognormal statistical distributions was established, and the model had well‐fitting results with the experimental results. [ABSTRACT FROM AUTHOR]

This article studied the mechanical properties and constitutive model of fiber‐reinforced coral aggregate concrete (FRCAC). The test results show that basalt fibers, carbon fibers, and polypropylene fibers (BFs, CFs, and PFs) can enhance the cube compressive strength and splitting tensile strength of coral aggregate concrete (CAC), but there are optimum contents. The optimal content of BFs, CFs, and PFs are 0.8%, 1.5%, and 0.3%, respectively. Fibers increase slightly the elastic modulus of FRCAC. The peak stress, peak strain, and ultimate strain of CAC can be improved by fibers, and the improvement effect is CFs, BFs, and PFs in descending order. According to the experimental results, a damage constitutive model suitable for FRCAC was proposed, which can efficiently indicate the stress–strain relationship of FRCAC. The damage parameter in the model can predict the damage evolution process of FRCAC. [ABSTRACT FROM AUTHOR]

Geopolymer concrete (GPC) is regarded as a more environmentally friendly construction material compared to conventional cement concrete, and its exceptional environmental capabilities are highly favored by the contemporary construction sector. Studying the mechanical properties of GPC upon exposure to elevated temperatures is a crucial aspect of evaluating structural damage and enhancing fire safety measures. Nevertheless, properly predicting the compressive performance of GPC upon exposure to high temperatures remains a formidable task. This study employs various machine learning techniques, such as single models, integrated models, neural network models, and hybrid models, to predict the compressive strength of GPC from room temperature to 1000°C. The results of each model are summarized, and the significant factors influencing compressive strength are analyzed to evaluate the thermal behavior of GPC. These findings offer recommendations for future in‐depth machine learning applications in the GPC field. The K‐fold cross‐validation shows that the hybrid model genetic algorithm–random forest has the highest prediction accuracy, while the single model performs the worst. Other models also provide favorable prediction results. The feature importance analysis revealed that the compressive strength of GPC is primarily influenced by heating temperature (HT) and hydroxide ion concentration, with fly ash and ground granulated blast furnace slag content being secondary factors. The partial dependence plot‐2D analysis indicates that as HTs increase, the influence of other variables on GPC compressive strength decreases significantly. These findings can inform the design of GPC mixing ratios for high‐temperature exposure. The machine learning technique proposed in this study accurately predicts GPC compressive strength across various temperatures, reducing experimental time and costs while promoting the GPC sector. [ABSTRACT FROM AUTHOR]

Although the double recessive genetic male sterility (GMS) line, ms5ms6, of upland cotton has been extensively used in breeding programs, possible mechanisms of pollen abortion remain unknown. In this study, the development stages of anther of this line were cytologically investigated. The results showed that the initial abortive development of sterile microspores occurred at meiosis I. Further cytological analyses revealed that deformed tapetal cells due to disintegration of middle layer may accelerate the process of apoptosis, leading to vacuolization. Moreover, pollen mother cells of sterile plants went into abnormal meiosis in which tetraspore, trispore, bispore, and even paraspore were formed. Also, there was no pollen formation possibly, because of anther deformity and narrow microsporangium as well as premature disintegration of tapetum in the GMS line. Taken together, the results indicated that abnormal development of tapetum may be the main reason for male sterility. © 2015 Friends Science Publishers [ABSTRACT FROM AUTHOR]