Exploring Microstructure, Wear Resistance, and Electrochemical Properties of AlSi10Mg Alloy Fabricated Using Spark Plasma Sintering

Al-Si-Mg alloy has excellent casting performance due to its high silicon content, but the coarse eutectic silicon phase can lead to a decrease in its mechanical properties. Samples of AlSi10Mg alloy were prepared by using a spark plasma sintering method, and it was found that sintering temperature has a significant impact on the grain size, eutectic silicon size and wear and corrosion properties after heat treatment. At a sintering temperature of 525 °C, the alloy exhibits the best wear performance with an average friction coefficient of 0.29. This is attributed to the uniform precipitation of fine eutectic silicon phases, significantly improving wear resistance and establishing adhesive wear as the wear mechanism of AlSi10Mg alloy at room temperature. The electrochemical performance of AlSi10Mg sintered at 500 °C is the best, with Icorr and Ecorr being 1.33 × 10−6 A·cm−2 and −0.57 V, respectively. This is attributed to the refinement of grain size and eutectic silicon size, as well as the appropriate Si volume fraction. Therefore, optimizing the sintering temperature can effectively improve the performance of AlSi10Mg alloy

In-situ synthesized a dual-scale Ti2AlC reinforced TiAl composites with superior mechanical properties

To enhance the mechanical properties and service temperature of TiAl alloy, the dual-scale Ti2AlC particles reinforced TiAl composites were successfully designed and fabricated by spark plasma sintering (SPS), utilizing pre-alloyed Ti–48Al–2Nb–2Cr powder and multi-walled carbon nanotubes. The TiAl composites exhibited a fully lamellar structure, with micro-laminated Ti2AlC particles formed at grain boundaries and nano-laminated Ti2AlC particles precipitated at the interfaces of α2 and γ lamellae by adding 0.5 wt% multi-walled carbon nanotubes. The TiAl composites exhibited excellent mechanical properties at room temperature and elevated temperatures. The ultrahigh tensile strength of TiAl composite was 599.6 MPa at 800 °C which was improved by 28.3 % compared with TiAl matrix, while the fracture strain remained 4.2 % without sacrifice. These superior mechanical properties were mainly attributed to the refinement strengthening, solid solution strengthening, and the formation of dual-scale Ti2AlC particles. Moreover, the dual-scale Ti2AlC particles reinforced α2 and γ lamellar interfaces and lamellar colony boundaries resulting in improvement of strength and toughness simultaneously. The TiAl composite was reinforced by dual-scale Ti2AlC particles, which expected to further break the property limitation of TiAl alloy and expanded its application at high temperature

The fungal myosin I is essential for <i>Fusarium</i> toxisome formation

<div><p>Myosin-I molecular motors are proposed to function as linkers between membranes and the actin cytoskeleton in several cellular processes, but their role in the biosynthesis of fungal secondary metabolites remain elusive. Here, we found that the myosin I of <i>Fusarium graminearum</i> (FgMyo1), the causal agent of Fusarium head blight, plays critical roles in mycotoxin biosynthesis. Inhibition of myosin I by the small molecule phenamacril leads to marked reduction in deoxynivalenol (DON) biosynthesis. FgMyo1 also governs translation of the DON biosynthetic enzyme Tri1 by interacting with the ribosome-associated protein FgAsc1. Disruption of the ATPase activity of FgMyo1 either by the mutation E420K, down-regulation of FgMyo1 expression or deletion of FgAsc1 results in reduced Tri1 translation. The DON biosynthetic enzymes Tri1 and Tri4 are mainly localized to subcellular structures known as toxisomes in response to mycotoxin induction and the FgMyo1-interacting protein, actin, participates in toxisome formation. The actin polymerization disruptor latrunculin A inhibits toxisome assembly. Consistent with this observation, deletion of the actin-associated proteins FgPrk1 and FgEnd3 also results in reduced toxisome formation. Unexpectedly, the FgMyo1-actin cytoskeleton is not involved in biosynthesis of another secondary metabolite tested. Taken together, this study uncovers a novel function of myosin I in regulating mycotoxin biosynthesis in filamentous fungi.</p></div

FgMyo1 is required for toxin biosynthesis.

<p><b>(A)</b> Localization of FgMyo1-RFP in hyphae of PH-1::FgMyo1-RFP growth in toxin non-inducing media PDB and MM at 28°C for 48 h. Bar = 10 μm. <b>(B</b>) FgMyo1-RFP was co-localized with Tri1-GFP under the toxin inducing condition. Bar = 10 μm. <b>(C)</b> The interaction of FgMyo1 with Tri1 was confirmed by co-immunoprecipitation (Co-IP) analysis. Total proteins (input) extracted from the strain bearing FgMyo1-3×Flag and Tri1-GFP constructs or a single construct (FgMyo1-3×Flag or Tri1-GFP) were subjected to SDS-PAGE, and immunoblots were incubated with anti-Flag and anti-GFP antibodies, as indicated (Input panel). Each protein sample was pulled down using anti-Flag agarose and further detected with anti-GFP antibody (Flag pull-down panel). The protein samples were also incubated with the anti-GAPDH antibody as a reference. <b>(D)</b> The interaction of FgMyo1 with Tri1 was confirmed by bimolecular fluorescence complementation (BiFC) analysis. The constructs of pFgTri1-YFP^N and pFgMyo1-YFP^C were co-transformed into PH-1 to generate the strain FgTri1-YFP^N+FgMyo1-YFP^C. The strains bearing a single construct (FgMyo1-YFP^C or FgTri1-YFP^N) were used as negative controls. The YFP signals in hyphae of each strain grown in the TBI medium were examined under a confocal microscope. Bar = 10 μm. <b>(E)</b> The sensitivity of FgMyo1 derived mutants towards phenamacril. The wild-type PH-1, FgMyo1 silencing mutant FgMyo1-S2, inducible mutant Pzear-FgMYO1, and the point mutation strain FgMyo1^E420K were incubated on PDA supplemented with 0.3 μg/ml phenamacril (left panel). For the inducible mutant, PDA was also added with (+) or without (-) the inducer 30 μg/ml β-estradiol. Mycelial growth inhibition of each strain by phenamacril was quantified (right panel). Values on the bars followed by the same letter are not significantly different according to a Fisher’s least significant difference (LSD) test at <i>P</i> = 0.05. <b>(F)</b> The toxisome formation patterns in FgMyo1 derived mutants. Each strain was grown in TBI, and images were taken after incubation for 48 h (left-upper panel). The accumulation of Tri1-GFP protein in each strain was determined by western blot assay with the anti-GFP antibody. The protein samples were also incubated with the anti-GAPDH antibody as a reference (left-lower panel). The intensities of GFP signals in each strain were also quantified. Values on the bars followed by the same letter are not significantly different according to a Fisher’s least significant difference (LSD) test at <i>P</i> = 0.05 (right panel). <b>(G)</b> The DON production of FgMyo1 derived mutants. DON was extracted from mycelia of each strain grown in TBI for 7 days. Values on the bars followed by the same letter are not significantly different according to a Fisher’s least significant difference (LSD) test at <i>P</i> = 0.05.</p

A proposed model showing the role of FgMyo1 in toxisome formation.

<p>Trichothecene biosynthesis enzymes (Tri proteins) are produced at a low level under toxin noninducing conditions. In toxin inducing conditions, FgMyo1 directly participates in remodeling the endoplasmic reticulum (ER) via the myosin-actin cytoskeleton to form the spherical and ovoid structures termed “<i>Fusarium</i> toxisomes.” In addition, FgMyo1 interacts with FgAsc1 indirectly to enhance the translation of Tri proteins. Phenamacril is able to suppress toxisome formation by inhibiting the ATPase activity of FgMyo1, and subsequently reduces the biosynthesis of DON in <i>Fusarium graminearum</i>.</p

The actin cytoskeleton is involved in toxisome formation.

<p><b>(A)</b> The interaction of Actin-RFP and Tri1-GFP was verified by the Co-IP assay. Total proteins (input) extracted from the strain bearing Actin-RFP and Tri1-GFP constructs or a single construct (Actin-RFP or Tri1-GFP) were subjected to SDS-PAGE, and immunoblots were incubated with anti-GFP and anti-RFP antibodies, as indicated (Input panel). Each protein sample was pulled down using anti-GFP agarose and further detected with anti-RFP antibody (GFP pull-down panel). The protein samples were also incubated with the anti-GAPDH antibody as a reference. <b>(B)</b> Co-IP analysis for verification of the interaction between FgMyo1-GFP and Actin-RFP. Total proteins (input) extracted from the strain bearing Actin-RFP and FgMyo1-GFP constructs or a single construct (Actin-RFP or FgMyo1-GFP) were subjected to SDS-PAGE, and immunoblots were incubated with anti-Flag and anti-GFP antibodies, as indicated (Input panel). Each protein sample was pulled down using anti-GFP agarose and further detected with anti-RFP antibody (GFP pull-down panel). The protein samples were also incubated with the anti-GAPDH antibody as a reference. <b>(C)</b> The actin polymerization inhibitor latrunculin A inhibited toxisome formation. After growth in TBI for 24 h, ΔTri1::Tri1-GFP was treated with 0.1 μg/ml latrunculin A for another 24 h before examination (left panel). The solvent DMSO was used as a control. Bar = 10 μm. The accumulation of Tri1-GFP protein was further verified by western blotting assay using the anti-GFP antibody (right panel). The protein samples were also incubated with the anti-GAPDH antibody as a reference. <b>(D)</b> DON was extracted from mycelia of PH-1 grown in TBI supplemented with 0.1 μg/ml latrunculin A. The solvent DMSO was used as a control. Values on the bars followed by different letters are significantly different according to a Fisher’s least significant difference (LSD) test at <i>P</i> = 0.05.</p

Deletion of the actin associated protein genes <i>FgPrk1</i> or <i>FgEnd3</i> hinders toxisome formation.

<p><b>(A)</b> Toxisome formation in ΔFgPrk1 and ΔFgEnd3 (left panel). The images were taken after each strain bearing Tri1-GFP was incubated in TBI for 48 h. Bar = 10 μm. The accumulation of Tri1-GFP protein in each strain was determined by using a western blot assay with the anti-GFP antibody (right panel). The protein samples were also incubated with the anti-GAPDH antibody as a reference. <b>(B)</b> Production of DON in ΔFgPrk1 and ΔFgEnd3 after each strain was cultured in TBI for 7 days. <b>(C)</b> The sensitivity of ΔFgPrk1, ΔFgEnd3 and their complementation strains (ΔFgPrk1-C and ΔFgEnd3-C) towards phenamacril and carbendazim. Each strain was cultured on PDA supplemented with 0.3 μg/ml phenamacril or carbendazim (left panel). Mycelial growth inhibition of each strain by phenamacril or carbendazim was quantified (right panel). Values on the bars for each fungicide treatment followed by different letters are significantly different according to a Fisher’s least significant difference (LSD) test at <i>P</i> = 0.05.</p

Phenamacril disrupted toxisome formation and subsequently inhibited DON production.

<p><b>(A)</b> Tri1-GFP localized to the spherical structures (termed as toxisomes) in hyphae grown in TBI but not in PDB or MM. Images were taken after each strain was incubated at 28 °C for 48 h. Bar = 10 μm. DIC indicates differential interference contrast. <b>(B)</b> After growth in TBI for 48 h, hyphae of ΔTri1::Tri1-GFP were stained with the ER-tracker red and examined for GFP and ER tracker signals. Bar = 10 μm. <b>(C)</b> After growth in TBI for 48 h, hyphae of PH-1::Tri1-GFP+H1-RFP were examined for the co-localization of H1-RFP and Tri1-GFP. Bar = 10 μm. <b>(D)</b> Hyphae of ΔTri1::Tri1-GFP were treated with 0.5 μg/ml phenamacril, or 1.4 μg/ml carbendazim for 24 h in TBI before examination for GFP signals. The solvent DMSO was used as a control. Bar = 10 μm. (<b>E)</b> Western blots of proteins isolated from the same set of samples used in 1D were detected with the anti-GFP or anti-GAPDH antibody. <b>(F</b>) DON production was assayed for the wild-type PH-1 growth in TBI supplemented with 0.5 μg/ml phenamacril or 1.4 μg/ml carbendazim. The solvent DMSO was used as a control. Values on the bars followed by the same letter are not significantly different according to a Fisher’s least significant difference (LSD) test at <i>P</i> = 0.05. (<b>G)</b> Phenamacril inhibited toxisome formation in hyphae of ΔTri1::Tri1-GFP inoculated on wheat leaf. <b>(H)</b> Efficiencies of phenamacril (375 g/ha) and carbendazim (750 g/ha) in controlling Fusarium head blight (FHB) and DON contamination in the field trials. Values on the bars for disease incidence or DON production followed by the same letter are not significantly different according to a Fisher’s least significant difference (LSD) test at <i>P</i> = 0.05.</p

The myosin I-actin cytoskeleton is not associated with aurofusarin biosynthesis.

<p><b>(A)</b> Comparisons of red pigment (aurofusarin) biosynthesis among the wild type and various mutants constructed in this study. Images were taken after each strain was grown on PDA or in liquid PDB. The myosin I inhibitor phenamacril and the actin polymerization inhibitor latrunculin A did not inhibit aurofusarin biosynthesis. (<b>B</b>) Co-localization analysis for Tri1-GFP or the peroxisome indicator FgPex3-GFP with the aurofusarin biosynthetic enzyme AurJ-RFP. A strain dual-labeled with either AurJ-RFP and Tri1-GFP or AurJ-RFP and FgPex3-GFP was grown in TBI for 48 h before observation. Bar = 10 μm. (<b>C</b>) Phenamacril and latrunculin A did not affect cellular localization of AurJ-RFP.</p

FgMyo1 regulates translation of Tri1 via interacting with the ribosomal protein FgAsc1.

<p><b>(A)</b> The interaction of FgMyo1-GFP and Asc1-RFP was verified by the Co-IP assay (left panel). FgMyo1-GFP was co-localized with FgAsc1-RFP under the toxin inducing conditions. Bar = 10 μm. (<b>B</b>) Localization of FgAsc1-RFP in hyphae of PH-1::FgAsc1-RFP+Tri1-GFP grown in toxin non-inducing medium PDB (upper panel) or toxin inducing medium TBI (lower panel) for 48 h. Bar = 10 μm. (<b>C</b>) ΔFgAsc1 exhibited dramatically reduced hyphal growth on PDA. <b>(D)</b> Toxisome formation was not detected in ΔFgAsc1 grown in TBI medium (left panel). Bar = 10 μm. The accumulation of Tri1-GFP protein in ΔFgAsc1 was determined by a western blot assay with the anti-GFP antibody (right panel). <b>(E)</b> DON production was under a detectable level in ΔFgAsc1. Values on the bars followed by the same letter are not significantly different according to a Fisher’s least significant difference (LSD) test at <i>P</i> = 0.05. <b>(F)</b> Comparisons in localization (left panel) and translation level (right panel) of the FK506-binding protein Fkbp54 tagged with GFP in the wild type and in the ΔFgAsc1 mutant. Bar = 10 μm.</p