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The impact abrasive wear behaviors of light-weight austenitic Fe-24Mn-7Al-lC steel with increasing impact wear conditions were studied by comparing with the modified Hadfield (Mnl3Cr2) steel. Wear tests were performed with the MLD-10 abrasive wear testing machine. Main parameters such as impact energy, impacting frequency and wear time were evaluated. To explore the abrasive wear behaviors under different impact energies, the parameters including mass loss, wear resistance and hardness were evaluated in detail. The microstructures of the steels were further analyzed using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Results showed that the light-weight austenitic Fe-24Mn-7Al-lC steel had a better wear resistance than Mnl3Cr2 steel under the impact energy tested. The wear resistance of light-weight austenitic Fe-24Mn-7Al-lC steel was about 1. 09 – 1. 17 times as high as that of Mnl3Cr2 steel under low and medium impact energy (0. 5 – 2. 0 J) conditions, and 1. 41 times under high impact energy (4. 0 J) condition. In Mnl3Cr2 steel, the evolution of dislocation substructure with increasing impact energy showed typical stacking fault, interaction of twins and dislocations, as well as mechanical twins. The high work-hardening rate in Fe-24Mn-7Al-lC steel was caused by Taylor lattice and high density of dislocation tangles.

Fusarium wilt, one of the destructive diseases of cucumber can be effectively controlled by using biocontrol agents such as Trichoderma harzianum. However, the mechanisms controlling T. harzianum-induced enhanced resistance remain largely unknown in cucumber plants. Here we screened the potent T. harzianum isolate TH58 that could effectively control F. oxysporum (FO). Glasshouse efficacy trials also showed that TH58 decreased disease incidence by 69.7 %. FO induced ROS over accumulation, while TH58 inoculation suppressed ROS over accumulation and improved root cell viability under F. oxysporum infection. TH58 inoculation could reverse the FO-induced cell division block and regulate the proportional distribution of nuclear DNA content through inducing 2C fraction. Moreover, the expression levels of cell cycle-related genes such as CDKA, CDKB, CycA, CycB, CycD3;1 and CycD3;2 in TH58 - pre-inoculated seedlings were up-regulated compared with those infected with FO alone. Taken together, these results suggest that T. harzianum improved plant resistance against Fusarium wilt disease via alterations in nuclear DNA content and cell cycle-related genes expression that might maintain a lower ROS accumulation and higher root cell viability in cucumber seedlings.

Mitochondrial uncoupling proteins (UCPs) play crucial role in the regulation of metabolic thermogenesis, photosynthesis, redox poise, and response to stress situations. However, the involvements UCPs and its regulatory mechanisms in plant mitochondrial respiration and electron transport have not yet been fully substantiated. In this article, we show that UCP is essential for effective respiratory balance and mitochondrial electron transport poise under chilling stress in tomato. Compared with pTRV (non-silenced) plants, suppression of LeUCP the expression by virus-induced gene silencing significantly decreased the total, SHAM-resistant, and CN-resistant respiratory rates, but increased cytosolic glycolysis pathway-related gene expression and enzymes’ activities under chilling stress. The transcripts’ abundances of UCRH, COX1, COX2, AOX1a, AOX2, and NDC1 genes involved in main and bypass miETC components were decreased, while those of NDUO and SDH4 were slightly increased in the leaves of LeUCP-silenced plants. In addition, silencing of LeUCP aggravated H2O2 and O2 − accumulation levels in leaves under chilling stress. Our results provide strong evidence that LeUCP is critical for respiratory homeostasis and mitochondrial electron transport signaling under chilling stress in tomato.