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Since emerging in Brazil in 1985, wheat blast has spread throughout South America and recently appeared in Bangladesh and Zambia. Here we show that two wheat resistance genes, Rwt3 and Rwt4, acting as host-specificity barriers against non-Triticum blast pathotypes encode a nucleotide-binding leucine-rich repeat immune receptor and a tandem kinase, respectively. Molecular isolation of these genes will enable study of the molecular interaction between pathogen effector and host resistance genes.

We study the statistical distributions of the output signals of a superconducting hot-electron bolometer (HEB) detector exposed to weak photon pulses of 1 THz (terahertz) frequency. Pulses with variable photon numbers were generated through strongly non-degenerate parametric downconversion (PDC) in a LiNbO3 crystal at 4.8 K. Fundamental differences in histograms are found between two PDC pumping modes, with pulse widths of 28 ps and 10 ns. HEB response to a picosecond THz pulse was detected in the form of a single elementary electrical pulse (SEP), with the average amplitude proportional to radiation intensity and dispersion relative to the bolometer's dark current. HEB responses to extremely weak radiation intensities have been recorded using nanosecond pulsed illumination. We found that nanosecond histograms are asymmetrical and broaden as radiation intensity increases, indicating that the nanosecond response consists of several SEPs. Poisson–Gauss approximation of histograms indicates that not only the average number of SEPs increase but also the average amplitude of a SEP increases with increasing power of incident THz radiation. [ABSTRACT FROM AUTHOR]

The COVID-19 outbreak has influenced virtually all aspects of our life, in particular, hundreds of millions of people around the world have been forced to study online. To observe the practical realization of emergency remote teaching of chemistry during the first wave of COVID-19 in Russia we gave the survey to 217 teachers and 355 students from more than 50% regions of Russia about their experience during distance learning of chemistry. 17% of students were lacking chemistry lessons at all. We compared this with the situation in Letovo international boarding school in Moscow and found relative success in terms of lessons adaptation and overall satisfaction compared to the Russia-wide survey. This might be because of the fine educational organization effort and implemented learning management system (LMS). There is a high probability of a second COVID-19 wave or any other occasion that may lead to sudden change to distance learning. Teacher community should learn from world-wide and country-wide experiences of the first COVID-19 wave to become prepared for future challenges. Those preparation measures may include implementing LMS and strategy development.

SUMMARY: Plant fungal parasites manipulate host metabolism to support their own survival. Among the many central metabolic pathways altered during infection, the glyoxylate cycle is frequently upregulated in both fungi and their host plants. Here, we examined the response of the glyoxylate cycle in bread wheat (Triticum aestivum) to infection by the obligate biotrophic fungal pathogen Puccinia striiformis f. sp. tritici (Pst). Gene expression analysis revealed that wheat genes encoding the two unique enzymes of the glyoxylate cycle, isocitrate lyase (TaICL) and malate synthase, diverged in their expression between susceptible and resistant Pst interactions. Focusing on TaICL, we determined that the TaICL B homoeolog is specifically upregulated during early stages of a successful Pst infection. Furthermore, disruption of the B homoeolog alone was sufficient to significantly perturb Pst disease progression. Indeed, Pst infection of the TaICL‐B disruption mutant (TaICL‐BY400*) was inhibited early during initial penetration, with the TaICL‐BY400* line also accumulating high levels of malic acid, citric acid, and aconitic acid. Exogenous application of malic acid or aconitic acid also suppressed Pst infection, with trans‐aconitic acid treatment having the most pronounced effect by decreasing fungal biomass 15‐fold. Thus, enhanced TaICL‐B expression during Pst infection may lower accumulation of malic acid and aconitic acid to promote Pst proliferation. As exogenous application of aconitic acid and malic acid has previously been shown to inhibit other critical pests and pathogens, we propose TaICL as a potential target for disruption in resistance breeding that could have wide‐reaching protective benefits for wheat and beyond. Significance Statement: Isocitrate lyase (ICL) is a unique enzyme of the glyoxylate cycle that frequently accumulates in fungi and their host plants. We uncovered a critical role for wheat ICL in supporting Puccinia striiformis f. sp. tritici (Pst) infection. Disruption of ICL function in wheat prevented Pst disease progression, likely due to the accumulation of glyoxylate cycle intermediates that can suppress Pst infection. ICL thus represents a new potential target for disruption in resistance breeding. [ABSTRACT FROM AUTHOR]

Potassium manganese fluoride phosphate, KMnPO4F, has been obtained through mild hydrothermal synthesis and characterized by scanning electron microscopy, microprobe analysis and X-ray diffraction. The compound possesses an orthorhombic symmetry and chiral space group P212121 with a = 4.7884(2), b = 9.0172(4), c = 9.5801(4) Å, and Z = 4. Its crystal structure is composed of Mn3+O4F square pyramids sharing vertices with PO4 tetrahedra. This anionic framework is neutralized by K+ cations. As the temperature decreases, a short-range correlation state (Tmax ∼ 35 K) of KMnPO4F is formed, followed by the establishment of antiferromagnetic (AFM) long-range order at TN = 25 K. The latter is marked by sharp λ-type anomalies in both Fisher's specific heat d(χkT)/dT and heat capacity Cp. Pulsedmagnetic field measurements on the single crystals identify the a axis as the easy magnetic axis and reveal a spin-flop transition at μ0Hspin-flop = 19 T. Density functional theory indicates that in variance with the three-dimensional network of KMnPO4F, it is a two-dimensional Ising magnetic system represented by buckled layers of integer spins S = 2 of Mn3+ ions. The strongest AFM exchange interaction, J1 ∼ -13 K, couples Mn3+ ions into linear chains running along the a axis. The chains themselves are ferromagnetically connected (J3 ∼ -4 K) within the ab plane. The interplane AFM exchange interaction (J2 ∼ -1 K) is weak and frustrated. [ABSTRACT FROM AUTHOR]

The branched complexes of Schiff bases with various iron(III) salts, named G2-[L2Fe]+A− (A− is NO3−, Cl−, PF6−), were synthesized using the condensation reaction between carbazole derivatives of salicylic aldehyde and N'-ethylethylenediamine and characterized by various spectroscopic methods (GPC, IR, 1H NMR, UV/Vis). The studies revealed that the coordination of the two ligand molecules to metal occurs through the nitrogen ions and oxygen atom of azomethine to form a homoleptic system. All the synthesized coordination compounds were examined for their thermal, optical, and magnetic features. Static magnetic measurements showed that only G2-[L2Fe]Cl was in a single-phase HS state, whereas the Fe(III) ions of G2-[L2Fe]NO3 and G2-[L2Fe]PF6 at room temperatures were in mixed low-spin (LS, S = 1/2) and high-spin (HS, S = 5/2) states: 58.9% LS/41.1% HS for G2-[L2Fe]NO3, 56.1% LS and 43.9% HS for G2-[L2Fe]PF6. All G2-[L2Fe]+A− complexes demonstrate antiferromagnetic exchange interactions between neighboring Fe(III) ions. The ground spin state at 2.0 K revealed a Brillouin contribution from non-interacting LS ions and a proportion of the HS Fe(III) ions not participating in AFM interactions: 57%, 18%, and 16% for G2-[L2Fe]Cl, G2-[L2Fe]NO3 and G2-[L2Fe]PF6, respectively. EPR measurements confirmed the presence of magnetically active HS and LS states of Fe(III) ions and made it possible to distinguish two HS types-with strong low-symmetry (I-type) and weak, distorted octahedral environments (II-type). It was shown that G2-[L2Fe]+A− complexes are magnetically inhomogeneous and consist of two magnetic sub-lattices: AFM-correlated chains in layers from the I-type HS Fe(III) centers and dynamic short-range AFM ordered LS/II-type HS Fe(III) centers in the paramagnetic phase located between the layers. [ABSTRACT FROM AUTHOR]

This work continues the earlier studies focusing on fabrication of heterophase micropowders and consolidated ceramics based on HfB2–HfC–SiC ultra-high-temperature boride/carbide compositions via self-propagating high-temperature synthesis (SHS) and hot pressing (HP). The effect of NH4Cl addition on the morphology and microstructure of the SHS powders was studied. Composite micropowders characterized by particle size of 0.2–10 μm and 40–50% content of the submicron-sized fraction were fabricated. The structure, mechanical and thermophysical properties, kinetics and mechanism of high-temperature oxidation of hot-pressed ceramic materials composed of 57–72 wt % HfB2, 14–20 wt % HfCx, 10–14 wt % SiC, and 8–15 wt % HfO2 were studied. They are found to have hardness up to 18.9 GPa, crack resistance up to 9.7 MPa m0.5, bending strength up to 400 MPa, temperature diffusivity up to 22.6 mm2/s, and thermal conductivity up to 59 W/(m K). The power law describes their oxidation kinetics. The protection mechanism against oxidation involves the formation of a multilayered heterogenous oxide film consisting of HfO2, HfSiO4, and borosilicate glass. [ABSTRACT FROM AUTHOR]