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The three-parameter Weibull distribution has a strong ability to fit many kinds of experimental data, which provides a solution for using a unified expression to characterize the elastic-brittle, strain softening, elastic-plasticity, and other constitutive behaviors of rocks. Therefore, a statistical damage constitutive model based on three-parameter Weibull distribution was constructed through theoretical analysis and derivation. Its expression ability was verified by combining with the conventional triaxial compression test data of marble. Meanwhile, the application effect of this statistical damage constitutive model on granite and sandstone was analyzed. The results show that the statistical damage constitutive model of rock based on three-parameter Weibull distribution can well express elastic-brittle, elastic-plastic, strain softening behaviors of rock by setting reasonable constitutive parameters, which lays a theoretical foundation for constructing a unified rock constitutive model. Conventional triaxial tests of marble show that with the increasing of confining pressure (σ3= 5, 15, 25, 35 MPa), the plastic deformation increases and the failure mode gradually changes from brittle tensile failure to shear failure, showing brittle-ductile and brittle-plastic transition characteristics. And its constitutive behaviors are characterized by elastic-brittleness, strain softening, and elastic-plasticity, which can be well expressed by the statistical damage constitutive model. When σ3 is 25 and 35 MPa, sandstone samples show elastic-brittle behavior. And for granite samples, they show strain softening behavior when σ3 is 5 MPa. The statistical damage constitutive model is also suitable for describing both sandstone elastic-brittle behavior and granite strain softening behavior. It is concluded that the three-parameter Weibull distribution provides a useful approach to characterize various constitutive behaviors of rock, and the model has a wide potential in numerical simulation for mining engineering, geoengineering, and other rock engineering.

A series of heterocycle containing amide derivatives (1-28) were synthesised by the combination of acyl chlorides (1a, 2a) and heterocyclic/homocyclic ring containing amines, and their in vitro antifungal activity was evaluated against five plant pathogenic fungi, namely Gibberella zeae, Helminthosporium maydis, Rhizoctonia solani, Botrytis cinerea and Sclerotinia sclerotiorum. Results of antifungal activity analysis indicated that some of the products showed good to excellent antifungal activity, as compound 2 showed excellent activity against G. zeae and R. solani and potent activity against H. maydi, B. cinerea and S. sclerotiorum, and compounds 1, 8 and 10 also displayed excellent antifungal potential against H. maydi, B. cinerea and S. sclerotiorum and good activity against R. solani when compared with the standard carbendazim.

Brittleness is an important parameter to evaluate the performance of rock engineering. A scientific and reasonable brittleness evaluation method is of great significance to theoretical research and the engineering practice of rock mechanics. In view of the existing statistical constitutive models of rock based on the Weibull distribution being able to express various constitutive behaviors well, such as brittleness, plasticity, strain softening, this paper wants to determine rock brittleness from constitutive models. First, the parameter m, which can effectively reflect the overall characteristics of the rock stress-strain curve, and the parameter δ, which can reflect the post-peak characteristics, are selected. Then, a brittle evaluation method based on rock statistical damage constitutive parameters is proposed, and the brittleness index Bm (Bm = m·δ) is established. The feasibility is verified by the testing data of granite, sandstone and marble under different conditions. The results show that the brittleness of those hard rocks decrease with the increasing of confining pressure. For confining pressures of 5 MPa and 15 MPa, the brittleness of granite under triaxial unloading test is greater than that under triaxial compression test. The calculation results quantitatively reflect the brittle characteristics of sandstone, marble and granite in the test. Compared with the existing representative brittleness indexes, it is found that the brittleness index Bm can effectively reflect the characteristics of rock brittleness decreasing with increasing confining pressure and enhancement under unloading stress path. This paper provides a way to evaluate rock brittleness from the perspective of a constitutive model, which is helpful to enrich our understanding of rock brittleness.