Impulsive Fermi magnon-phonon resonance in antiferromagnetic CoF2CoF_{2}

Understanding spin-lattice interactions in antiferromagnets is one of the most fundamental issues at the core of the recently emerging and booming fields of antiferromagnetic spintronics and magnonics. Recently, coherent nonlinear spin-lattice coupling was discovered in an antiferromagnet which opened the possibility to control the nonlinear coupling strength and thus showing a novel pathway to coherently control magnon-phonon dynamics. Here, utilizing intense narrow band terahertz (THz) pulses and tunable magnetic fields up to 7 T, we experimentally realize the conditions of the Fermi magnon-phonon resonance in antiferromagnetic $CoF_{2}$. These conditions imply that both the spin and the lattice anharmonicities harvest energy transfer between the subsystems, if the magnon eigenfrequency $f_{m}$ is twice lower than the frequency of the phonon $2f_{m}=f_{ph}$. Performing THz pump-infrared probe spectroscopy in conjunction with simulations, we explore the coupled magnon-phonon dynamics in the vicinity of the Fermi-resonance and reveal the corresponding fingerprints of an impulsive THz-induced response. This study focuses on the role of nonlinearity in spin-lattice interactions, providing insights into the control of coherent magnon-phonon energy exchange

Nonreciprocity of Optical Absorption in the Magnetoelectric Antiferromagnet CuB₂O₄

The change in the absorption spectra due to reversal of the direction of light propagation (nonreciprocity of absorption) is a consequence of a simultaneous violation of both time-reversal and spatial-inversion symmetries. Here, we report on a high-resolution spectroscopic study of absorption nonreciprocity in the noncentrosymmetric multiferroic CuB2O4 below the antiferromagnetic transition temperature TN = 21 K in the commensurate phase in magnetic fields up to 0.5 T. The study was performed in a broad spectral region covering several exciton transitions, which all are followed by an anomalously rich structure due to the multiple exciton-magnon-phonon satellites. Two components were resolved for the spectral line near 1.4 eV corresponding to the exciton transition between the ground and the first excited state. A quantitative theory of the optical absorption and nonreciprocity at this line was developed. The theory takes into account the interference between the electric and magnetic dipole contributions to the absorption and gives an adequate explanation of the relevant effects

Serial Changes in Blood-Cell-Count-Derived and CRP-Derived Inflammatory Indices of COVID-19 Patients

The aim of the study was to investigate the serial changes in inflammatory indices derived from blood cell counts and C-reactive protein (CRP) levels in COVID-19 patients with good and poor outcomes. We retrospectively analyzed the serial changes in the inflammatory indices in 169 COVID-19 patients. Comparative analyses were performed on the first and last days of a hospital stay or death and serially from day 1 to day 30 from the symptom onset. On admission, non-survivors had higher CRP to lymphocytes ratio (CLR) and multi-inflammatory index (MII) values than survivors, while at the time of discharge/death, the largest differences were found for the neutrophil to lymphocyte ratio (NLR), systemic inflammation response index (SIRI), and MII. A significant decrease in NLR, CLR, and MII by the time of discharge was documented in the survivors, and a significant increase in NLR was documented in the non-survivors. The NLR was the only one that remained significant from days 7–30 of disease in intergroup comparisons. The correlation between the indices and the outcome was observed starting from days 13–15. The changes in the index values over time proved to be more helpful in predicting COVID-19 outcomes than those measured on admission. The values of the inflammatory indices could reliably predict the outcome no earlier than days 13–15 of the disease

Structure, Thermal Properties and Proton Conductivity of the Sulfonated Polyphenylquinoxalines

This paper briefly reviews the results of scientific research on the proton conductivity of sulfonated polyphenylquinoxalines. Synthesis, structure (IR spectroscopy, SEM, quantum-chemical modeling, molecular weight distribution), moisture capacity, thermal properties, and proton conductivity of sulfonated polyphenylquinoxalines (sulfur content 2.6, 4.2, 5.5, and 7%) were studied. The relative stable configurations of sulfonated polyphenylquinoxalines with different positions of benzene rings and sulfogroups with the help of quantum chemical modeling were modeled. Sulfonation of the starting polyphenylquinoxalines was confirmed by IR spectroscopy and elemental analysis. The SEM method was used to study the surface of sulfonated polyphenylquinoxalines, and sulfonation regions were found. It was shown that sulfonated polyphenylquinoxalines contain water and are stable up to 250 °C; on further heating, the decomposition of the sulfogroups occurs. The conductivity of the obtained polymer electrolytes was studied by impedance spectroscopy, and long-term tests were carried out. It is shown that the proton conductivity at an ambient humidity of 98 rel. % reaches values 10−6–10−3 S/cm depending on the degree of sulfonation. It was shown that even after long-term storage in air (7 years), samples of sulfonated polyphenylquinoxalines with a high sulfur content of 7% at 98% air humidity have a conductivity of 8 × 10−4 S/cm

A new plant protein interacts with eIF3 and 60S to enhance virus-activated translation re-initiation

The plant viral re-initiation factor transactivator viroplasmin (TAV) activates translation of polycistronic mRNA by a re-initiation mechanism involving translation initiation factor 3 (eIF3) and the 60S ribosomal subunit (60S). QJ; Here, we report a new plant factor-re-initiation supporting protein (RISP)-that enhances TAV function in re-initiation. RISP interacts physically with TAV in vitro and in vivo. Mutants defective in interaction are less active, or inactive, in transactivation and viral amplification. RISP alone can serve as a scaffold protein, which is able to interact with eIF3 subunits a/c and 60S, apparently through the C-terminus of ribosomal protein L24. RISP pre-bound to eIF3 binds 40S, suggesting that RISP enters the translational machinery at the 43S formation step. RISP, TAV and 60S co-localize in epidermal cells of infected plants, and eIF3-TAV-RISP-L24 complex formation can be shown in vitro. These results suggest that RISP and TAV bridge interactions between eIF3-bound 40S and L24 of 60S after translation termination to ensure 60S recruitment during repetitive initiation events on polycistronic mRNA; RISP can thus be considered as a new component of the cell translation machinery

How much can we learn about the function of bacterial rRNA modification by mining large-scale experimental datasets?

Modification of ribosomal RNA is ubiquitous among living organisms. Its functional role is well established for only a limited number of modified nucleotides. There are examples of rRNA modification involvement in the gene expression regulation in the cell. There is a need for large data set analysis in the search for potential functional partners for rRNA modification. In this study, we extracted phylogenetic profile, genome neighbourhood, co-expression and phenotype profile and co-purification data regarding Escherichia coli rRNA modification enzymes from public databases. Results were visualized as graphs using Cytoscape and analysed. Majority linked genes/proteins belong to translation apparatus. Among co-purification partners of rRNA modification enzymes are several candidates for experimental validation. Phylogenetic profiling revealed links of pseudouridine synthetases with RF2, RsmH with translation factors IF2, RF1 and LepA and RlmM with RdgC. Genome neighbourhood connections revealed several putative functionally linked genes, e.g. rlmH with genes coding for cell wall biosynthetic proteins and others. Comparative analysis of expression profiles (Gene Expression Omnibus) revealed two main associations, a group of genes expressed during fast growth and association of rrmJ with heat shock genes. This study might be used as a roadmap for further experimental verification of predicted functional interactions