Large‐acceptance diamond planar refractive lenses manufactured by laser cutting

For the first time, single‐crystal diamond planar refractive lenses have been fabricated by laser micromachining in 300 µm‐thick diamond plates which were grown by chemical vapour deposition. Linear lenses with apertures up to 1 mm and parabola apex radii up to 500 µm were manufactured and tested at the ESRF ID06 beamline. The large acceptance of these lenses allows them to be used as beam‐conditioning elements. Owing to the unsurpassed thermal properties of single‐crystal diamond, these lenses should be suitable to withstand the extreme flux densities expected at the planned fourth‐generation X‐ray sources.     

Quantum model of the magnetic dynamics of single-domain particles for describing their magnetization curves and Mössbauer spectra in a weak magnetic field

A universal approach to describing the equilibrium magnetization curves and relaxation Mössbauer spectra of magnetic nanoparticles is proposed for consistent analysis of magnetometry and gamma-resonance experimental data, based solving a quantum-mechanical problem for a particle with spin S that has intrinsic magnetic anisotropy and is positioned in an external magnetic field.     

Cooling of silver bullet laser diode submodules

The feasibility of using microfinned microchannel structures in copper heat exchangers designed for cooling semiconductor modules that pump powerful solid-state lasers is considered. Efficient heat exchangers are developed, and pumping modules with a continuous radiation power of 760 W are produced.     

Synthesis of 2-R-1,3-dioxanes, derivatives of functionally substituted aldehydes of vanillin series

By the condensation of substituted aldehydes of vanillin series with 1,3-propanediol in boiling benzene in the presence of sulfo cation exchanger FIBAN K-1 as catalyst functionally 2-R-substituted 1,3-dioxanes were synthesized.     

Diffusion reproduction processes

Interesting physics emerges from studying a population of reproducing individuals. Each can be regarded as a random walker, but it can either duplicate or die. Novel features of the collective behavior are quite surprising: if individuals reproduce or die freely, the life expectation is proportional to the size of the population, and if it is kept constant, the center of mass moves in space as if it were a single walker (i.e., the diffusion constant is independent of population's size). Biology-inspired interactions are also considered.     

Observation of the double optical-gamma resonance in Mössbauer spectra of 151 Eu in EuP 5 O 14 single crystal

A theoretical analysis has been made and calculation procedures have been developed for describing the hyperfine structure of ¹⁵¹Eu Mössbauer spectra and the effect of double optical-gamma resonance (DOGR) in the presence of hyperfine quadrupole interaction with an arbitrary symmetry of the electric field gradient tensor. An experimental setup was designed for DOGR-effect observation, incorporating the pumping argon laser and the tunable dye laser combined with the Mössbauer spectrometer on a common platform. The Mössbauer absorption spectra of ¹⁵¹Eu^3?+? nuclei in single crystals of europium pentaphosphate, EuP₅O₁₄, have been measured at T = 5 K and 80 K under the absence and presence of optical pumping tuned to the ⁷F $_{0}-^{5}$ D₀ electronic transition at the 578 nm wavelength. A simultaneous analysis of these spectra in terms of the spin Hamiltonian of hyperfine quadrupole interaction has allowed us to evaluate the DOGR-effect magnitude with the population of the excited (⁵D₀) electronic state under optical pumping of about 10 %.     

Anatomy of isolated monopole in Abelian projection of SU(2) lattice gauge theory

We study the structure of isolated static monopoles in the maximal Abelian projection of SU(2) lattice gluodynamics. Our estimation of the monopole radius is: R ^mon≈0.06 fm.     

Biodegradation of magnetic nanoparticles evaluated from Mössbauer and magnetization measurements

In order to extract a quantitative information about characteristics of the magnetic nanoparticles injected into a living organism it is necessary to define a model of the magnetic dynamics for fitting self-consistently the whole set of the experimental data, specifically, the evolution of Mössbauer spectral shape with temperature and external magnetic field as well as the magnetization curves. We have developed such a model and performed such an analysis of the temperature- and magnetic field-dependent spectra and magnetization curves of nanoparticles injected into mice. This allowed us to reliably evaluate changes in the characteristics of the residual particles and their chemical transformation to paramagnetic ferritin-like forms in different mouse organs as a function of time. Actually, the approach makes it possible to quantitatively characterize biodegradation and biotransformation of magnetic nanoparticles delivered in a body.