Microfabrication of Alkali Vapor MEMS Cells for chip-scale atomic clock

The technology of MEMS atomic cells containing rubidium or caesium vapors in an atmosphere of neon buffer gas has been developed. Two-chamber silicon cells containing an optical cavity, shallow filtration channels and a technical container for a solid-state alkali source have been implemented in a single-step process of anisotropic wet chemical etching. To prevent significant undercutting of the filtration channels during etching of the through silicon cavities, the shapes of the compensating elements at the convex corners of the silicon nitride mask have been calculated and the composition of the silicon etchant has been experimentally found. The sealing of the cells has been carried out by silicon-glass anodic bonding at a temperature of 250 оС. For this purpose the LK5 glass which has an increased ionic conductivity in comparison with the conventional glass Borofloat 33 was used. The best microfabricated cells allowed us to obtain estimates of the relative instability of the coherent population trapping resonance frequency at the level of 5·10-11 at 1 s

Analysis of the conduction mechanism through InSb quantum dot by tunnel CVC method

This work was supported by grants from the Russian Foundation for Basic Research Projects No. 16-07-00093 and No. 16-07-00185

Bistable arch-like beams with modulated profile as perspective supporting structures of a microelectromenchanical actuator

The static mechanical properties of a bistable electromechanical drive with arcuate suspension is investigated. The behaviour of an arcuate suspension and the influence of the beam thickness modulation on the stability of both stationary states is studied experimentally and theoretically. The influence of the beam shape modulation on its potential energy was determined with finite element analysis. The simulation results were verified experimentally. In the study, the optimal modulation configuration is determined. With help of this modification the sustainability of both mechanically stable states is significantly improved

Operation of a Bloch oscillator

We report the operation of a Bloch oscillator. The active medium was a staticvoltage driven, doped GaAs/AlAs superlattice which was electromagnetically coupled to a resonator. The oscillator produced tuneable microwave radiation (frequency ~ 60 GHz; power ~ 0.5 mW; efficiency ~ 4 %). The gain (~ 10^4 /cm) was due to the nonlinearity mediated by miniband electrons. We also present a theory of the oscillator. The Bloch oscillator should in principle be feasible for generation of radiation up to frequencies of 10 THz and more.Comment: 9 pages, 4 figure

Effect of subphase conditions on the formation of graphene Langmuir monolayer

This work was supported by grant from DAAD 4.9977.2017/5.2

Study of the surface microrelief of copper nanoparticles by the method of scanning probe microscopy

This work was supported by grants from the RFBR № 17-07-00407-а and № 17-32-50137-mol_nr

Investigation of the properties of quantum-dimensional semiconductor particles A3B5 by scanning probe microscopy, obtained by liquid chemical etching

The study was carried out with the financial support of the Russian Foundation for Basic Research in the framework of scientific projects 17-07-00407-а and 17-07-00139

ВОПРОСУ О ПРИМЕНЕНИИ ДАБИГАТРАНА ПРИ ПЕРСИСТИРУЮЩЕЙ ФИБРИЛЛЯЦИИ ПРЕДСЕРДИЙ (описание клинического случая)

The article highlights the prevention of thromboembolic events in patients with atrial fibrillation. The clinical case is presented and focused on direct thrombin inhibitor dabigatran administration as a secondary prevention strategy of thromboembolism (of an arrhythmogenic origin). В статье рассмотрены вопросы профилактики тромбоэмболических осложнений у больных с фибрилляцией предсердий. Приведено описание клинического случая с акцентом на возможную вторичную профилактику тромбоэмболий аритмогенного происхождения с применением прямого ингибитора тромбина дабигатрана.

Investigation of copper nanoparticles by the method of scanning probe microscopy

В данной работе получали мицеллярный раствор с НЧ меди, стабилизированными ПАВ анионного типа — додецилсульфатом натрия (ДДС) C12H25NaO4S в щелочной среде при pH ≈ 10, в качестве восстановителя использовали гидразин гидрат (ГГ) N2H4∙H2O. Спектрофотометрическое исследование полученного раствора на спектрофотометре SHIMADZU UV-2550 в диапазоне длин волн 190-900 нм показало наличие пика поглощения излучения при длине волны 580 нм, соответствующего НЧ меди.In this work a micellar solution was prepared with copper NPs stabilized by an anionic surfactant — sodium dodecyl sulfate (SDS) C12H25NaO4S at pH ≈ 10. Hydrazine hydrate (HH) N2H4∙H2O was used as the reducing agent. Spectrophotometric study of the obtained solution by means of SHIMADZU UV-2550 spectrophotometer in the wavelength range 190-900 nm is showed the presence of a radiation absorption peak at 580 nm corresponding of copper NPs. The study of images of copper NPs on the glass substrates with an ITO layer (Indium Tin Oxide) was carried out by scanning probe microscopy (SPM) in atomic-force microscopy (AFM) and scanning tunneling microscopy (STM) by means of NanoEducator. The AFM images were obtained and the current-voltage characteristics of the copper NPs were recorded (Fig. 1 (a) and (б), respectively).Работа выполнена при финансовой поддержке гранта Российского научного фонда (проект №14-12-00275) и Национального исследовательского Саратовского государственного университета