Design of infrared optical absorber using silver nanorings array made by a top-down process.

This paper presents the numerical simulation and fabrication of a metasurface composed of silver nanorings with a split-ring gap. These nanostructures can exhibit optically-induced magnetic responses with unique possibilities to control absorption at optical frequencies. The absorption coefficient of the silver nanoring was optimized by performing a parametric study with Finite Difference Time Domain (FDTD) simulations. The absorption and scattering cross sections of the nanostructures are numerically calculated to assess the impact of the inner and outer radii, the thickness and the split-ring gap of one nanoring, as well as the periodicity factor for a group of four nanorings. This showed full control on resonance peaks and absorption enhancement in the near infrared spectral range. The experimental fabrication of this metasurface made of an array of silver nanorings is achieved by e-beam lithography and metallization. Optical characterizations are then carried out and compared to the numerical simulations. In contrast to usual microwave split-ring resonator metasurfaces reported in literature, the present study shows both the realization by a top-down process and modelling performed in the infrared frequency range.

[Slow Formation and Degradation of γH2AX Foci in Human Skin Fibroblasts Exposed to Low-Dose X-Ray Radiation].

It was shown that the kinetics of changes of γH2AX foci number (marker of DNA double-strand breaks) in human skin fibroblasts after exposure to low doses of X-ray radiation (20, 40 and 80 mGy) differs from that observed after exposure to medium-low doses (160 and 240 mGy). After exposure to 160 and 240 mGy the highest number of γH2AX foci was detected at 30 min after exposure (first experimental point) and further their decrease was observed. At the same time we observed a fast phase of repair (upto 4 h), in which there was a decrease of the foci amount to ~50-60% and a slow phase of repair (from 4 h to 24 h). After 24 h only ~3-5% of the foci amount observed at 30 min after irradiation was left. After exposure to low doses, the foci number did not decrease during 2 h and even 24 h after exposure their amount was ~25% from that observed at maximum points (1 h after irradiation at 40 and 80 mGy and 2 h after irradiation at 20 mGy).

[Molecular docking: role of intermolecular contacts in formation of complexes of proteins with nucleotides and peptides].

Knowledge of 3D-structure of protein-ligand complex is a major prerequisite for understanding the functioning mechanism of cellular proteins and membrane receptors. This is also of a great help in rational drug design projects. In the present paper we briefly review the molecular docking approaches used to predict possible orientation of a ligand in the protein binding site. The recent trends to improve the accuracy and efficiency of docking algorithms are demonstrated with the results obtained in Laboratory of Biomolecular Modeling. Particular attention is paid to protein-ligand hydrophobic and stacking interactions responsible for molecular recognition of ligand fragments. Such type of interactions are not always adequately represented in scoring criteria of docking applications that leads to mismatch in 3D-structure complexes predictions. That is why further inquiry of methods to account for these interactions is now the area of active research.