Nonlinear metal-dielectric nanoantennas for light switching and routing

We introduce a novel hybrid metal-dielectric nanoantenna composed of dielectric (crystalline silicon) and metal (silver) nanoparticles. A high-permittivity dielectric nanoparticle allows to achieve effective light harvesting, and nonlinearity of a metal nanoparticle controls the radiation direction. We show that the radiation pattern of such a nanoantenna can be switched between the forward and backward directions by varying only the light intensity around the level of 11 MW/cm$^2$, with the characteristic switching time of 260 fs.Comment: 9 pages, 5 figures, submitted to New J. Phy

Coherent X-rays excited by a relativistic electron crossing a periodic stratified structure in Bragg scattering geometry

The dynamic theory of coherent X-rays excited by a relativistic electron crossing an artificial periodic stratified structure in Bragg scattering geometryhas been developed for the general case of asymmetric reflection. Expressions describing the spectral-angularcharacteristics of radiation have been derived and investigatedyesБелгородский госуниверсите

Manifestation of the effects of dynamic diffraction in the coherent X-ray radiation of relativistic electrons in a periodic layered medium

The possibility of manifestation of the effects of dynamic diffraction in the coherent X-ray radiation of relativistic electrons in a periodic layered medium is studied theoretically in this pape

Coherent X-radiation generated by relativistic elektron along its velocity in periodically lavered medium

Dynamic theory of coherent X-radiation generated by relativist.ic electron crossing multilayered medium is developed. It is found the radiation along the electron velocity vector in Bragg’s scattering geometry for general asymmetric case. The comparison of analogous radiation generated by relativist.ic electron in the single crystal medium is done. The developed theory predicts some conditions under which this coherent, radiation exists and also it describes its spectral and angular characteristicsyesБелгородский государственный университе

Coherent X-ray radiation along the velocity of relativistic electron crossing a periodic layered medium

In the present work, the dynamic theory of coherent X-radiation generated by a relativistic electron crossing the multilayered medium in the direction of the electron velocity vector is developed in Bragg scattering geometry for general case of asymmetric reflection. The comparison of the analogous radiation generated by a relativistic electron in the single crystal medium is mad

Hydrobionts of a freshwater oil-polluted northern lake: bioaccumulation of heavy metals in fish and the rate of ecosystem recovery

The response of phytoplankton, zooplankton, benthic and fish community structure to one of the biggest oil spill in history of Komi Republic (north-west part of Russia) was investigated using data from a long-term survey off the polluted lake. The characteristics of aquatic freshwater communities observed in the study area 10, 11 and 22 years after the spill (1994) were compared to find out the rate of natural recovery of the ecosystem after oil decontamination of bottom sediments. The concentrations of fifteen trace metals (Al, Cr, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sb, Pb, U, Bi, Th) were analyzed in the tissues (muscle) of three fish species. The concentrations of Al (3-309 mg/kg), Cr (0,1-3,71 mg/kg), Fe (8,6-317 mg/kg), and Cu (0,09-99 mg/kg) in fishes from polluted lake resulted in most cases higher than reference thresholds. Quantitative and qualitative indicators of aquatic invertebrates from polluted lake reach those one of unpolluted lake but do not fully recover 22 years after the spill, despite that oil concentration in water column and in bottom sediments was lower than reference tresholds. We conclude that natural recovery rate of aquatic freshwater ecosystems in northern regions after oil pollution is extremely low. The purification of water and bottom sediments of oil-polluted northern water bodies is necessary for stimulation of ecosystem restoration

Coherent x-ray radiation generated near the axis of the beam of relativistic electrons in an artificial periodic structure

A theory of the coherent X-ray radiation produced by a beam of relativistic electrons in an artificial periodic structure and propagating along the electron-beam axis is developed. Expressions describing the spectral-angular densities of parametric X-ray radiation in the direction close to the electron velocity vector (FPXR) and of transition radiation (TR) and their interference are obtained in the Bragg scattering geometry. An analysis based on the obtained expressions for the spectral-angular density shows possibilities of their use to determine the optimal parameters of the experiment recording the FPX

Human coronaviruses that can cause emergencies

The first coronavirus NСoV-B814 was isolated from humans in 1965 and did not survive to the present time. For a long time, it was believed that coronaviruses were not pathogenic to humans. They were not included in the list of particularly dangerous infections and represented a serious problem exclusively in veterinary medicine. But in 2002, after the SARS outbreak, scientists’ opinions changed. A new subtype of the coronavirus called SARS-CoV penetrated the human population. In 2012, it was possible to discover natural foci of Middle East Respiratory Syndrome. The epidemic of a new coronavirus infection that emerged in late 2019 and early 2020 attracted the attention of scientists around the world. The priority was a detailed and close study of all the varieties of this virus. This review describes seven types of coronaviruses that can cause emergencies in populations around the world

Hyaluronic acid at osteoarthrosis: intraarticulate introduction or synthesis stimulation?

In examination comparison of efficiency and safety of local therapy by a hyaluronic acid (HA) specimen and Autologous Conditioned Serum (ACS) is spent. The obtained data testify to the plus clinical effect of intraarticulate introduction ACS surpassing efficiency HA without essential side effects