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Plant susceptibility to pathogens is usually considered from the perspective of the loss of resistance. However, susceptibility cannot be equated with plant passivity since active host cooperation may be required for the pathogen to propagate and cause disease. This cooperation consists of the induction of reactions called susceptible responses that transform a plant from an autonomous biological unit into a component of a pathosystem. Induced susceptibility is scarcely discussed in the literature (at least compared to induced resistance) although this phenomenon has a fundamental impact on plant-pathogen interactions and disease progression. This review aims to summarize current knowledge on plant susceptible responses and their regulation. We highlight two main categories of susceptible responses according to their consequences and indicate the relevance of susceptible response-related studies to agricultural practice. We hope that this review will generate interest in this underestimated aspect of plant-pathogen interactions.

Cast four-component МАХ compounds (V1–xNbx)2AlC were prepared from V2O5–Nb2O5–Al–C powder mixtures by metallothermic SHS under 5 MPa of Ar and characterized by XRD, SEM/EDS, and video filming. Target product were found to contain (V1–xNbx)2AlC compounds and Al3Nb. Synthesized materials can find their application as structural materials in high-temperature applications in aggressive media.

We have studied the spontaneous comminution of cast materials consisting of a Mn-doped Cr2AlC MAX phase and chromium, manganese, and aluminum carbides and aluminides. The materials were prepared in the form of ingots by self-propagating high-temperature synthesis (SHS) in a 3-L reactor at an argon pressure p = 5 MPa. The starting mixtures consisted of manganese(IV) oxide, chromium(III) oxide, aluminum (ASD-1), and carbon. The presence of aluminum carbide (Al4C3) in a cast material has been shown to lead to spontaneous comminution of the cast material (without mechanical or chemical influences) into powders with a crystalline particle size under 100 μm. The particle size reduction has been shown to result from reaction between aluminum carbide and atmospheric moisture. The synthesized materials have been characterized by X-ray diffraction and X-ray microanalysis, and we have studied structural and phase states of particles of the desired products obtained as a result of self-comminution of a cast SHS material.

A material based on a (VCr)2AlC solid solution has been obtained for the first time by self-propagating high-temperature synthesis from a powder reaction mixture of vanadium(V) and chromium(III) oxides with aluminum and carbon (graphite). The synthesized material has been studied by X-ray diffraction and microstructural analyses. It has been shown that the product also contains vanadium and chromium carbides and intermetallics. The presence of these phases seems to be associated with the nonequilibrium character of the synthesis process due to a short “lifetime” of melt and its fast cooling and crystallization. The synthesized material is an electrical conductor, which demonstrates a metallic character of conductivity throughout the entire measured temperature range of 300–1300 K. The room-temperature specific resistance of the composite material based on a (Cr,V)2AlC solid solution is 1.14 µΩ m, which is higher than the specific resistance of the materials based on the Cr2AlC and V2AlC MAX phases. The microhardness of the synthesized material is 6.9 GPa.

High-temperature synthesis of cast composite materials in the Cr–Mn–Al–C system with various ratios between the Cr2AlC MAX phase and chromium and manganese aluminides and carbides was studied. Experiments were performed in a universal 3-L reactor under argon pressure Р = 5 MPa. Mixtures of powders of chromium(III) and manganese(II, IV) oxides and calcium peroxide with aluminum (ASD-I) and carbon were used as a charge. The synthesis features and the phase composition and microstructure of the target products are significantly influenced by the reactant ratio in the charge. At the stoichiometric ratio of the components corresponding to the Cr2AlC phase, a cast composite material consisting of the Cr2AlC MAX phase, chromium carbides Cr7C3 and Cr3C2, and chromium aluminide Cr5Al8 is formed. In the course of combustion of the charge with the component ratio corresponding to the Mn2AlC phase, a cast composite material consisting of manganese carbides (Mn3AlC, Mn0.545Al0.42C0.035) and aluminide (MnAl) is formed. When these compositions are combined in an 0.75 : 0.25 ratio, the final product is a composite material consisting of a solid solution based on the Cr2AlC MAX phase, manganese carbides (Mn3AlC), and chromium aluminides (Cr2Al). When these compositions are combined in an 0.5 : 0.5 ratio, the final product is a composite material consisting of the manganese-doped Cr2AlC MAX phase and of manganese (Mn14Al86, Mn22.5Al77.5) and chromium (Cr5Al8) aluminides. The final products were characterized by X-ray diffraction and local microstructural analysis.