Electric field induced strong localization of electrons on solid hydrogen surface: possible applications to quantum computing

Two-dimensional electron system on the liquid helium surface is one of the leading candidates for constructing large analog quantum computers (P.M. Platzman and M.I. Dykman, Science 284, 1967 (1999)). Similar electron systems on the surfaces of solid hydrogen or solid neon may have some important advantages with respect to electrons on liquid helium in quantum computing applications, such as larger state separation $\Delta E$, absence of propagating capillary waves (or ripplons), smaller vapor pressure, etc. As a result, it may operate at higher temperatures. Surface roughness is the main hurdle to overcome in building a realistic quantum computer using these states. Electric field induced strong localization of surface electrons is shown to be a convenient tool to characterize surface roughness.Comment: 4 pages, 3 figure

On the possibility to supercool molecular hydrogen down to superfluid transition

Recent calculations by Vorobev and Malyshenko (JETP Letters, 71, 39, 2000) show that molecular hydrogen may stay liquid and superfluid in strong electric fields of the order of $4\times 10^7 V/cm$. I demonstrate that strong local electric fields of similar magnitude exist beneath a two-dimensional layer of electrons localized in the image potential above the surface of solid hydrogen. Even stronger local fields exist around charged particles (ions or electrons) if surface or bulk of a solid hydrogen crystal is statically charged. Measurements of the frequency shift of the $1 \to 2$ photoresonance transition in the spectrum of two-dimensional layer of electrons above positively or negatively charged solid hydrogen surface performed in the temperature range 7 - 13.8 K support the prediction of electric field induced surface melting. The range of surface charge density necessary to stabilize the liquid phase of molecular hydrogen at the temperature of superfluid transition is estimated.Comment: 5 pages, 2 figure

Water-repellent coatings for surface and 3D wood processing

The paper presents the results of research in organic chemical compositions for hydrophobic protection of wood with the use of surface and three-dimensional coating techniques of impregnation and chemical compositions. Water absorption indicators, angles of contact on the surface of treated samples are detected herein. Kinetic equation of the moisture diffusion transition in capillary-porous structure of wood is suggested

Nonlinear two-level dynamics of quantum time crystals

A time crystal is a macroscopic quantum system in periodic motion in its ground state. In our experiments, two coupled time crystals consisting of spin-wave quasiparticles (magnons) form a macroscopic two-level system. The two levels evolve in time as determined intrinsically by a nonlinear feedback, allowing us to construct spontaneous two-level dynamics. In the course of a level crossing, magnons move from the ground level to the excited level driven by the Landau-Zener effect, combined with Rabi population oscillations. We demonstrate that magnon time crystals allow access to every aspect and detail of quantum-coherent interactions in a single run of the experiment. Our work opens an outlook for the detection of surface-bound Majorana fermions in the underlying superfluid system, and invites technological exploitation of coherent magnon phenomena – potentially even at room temperature

Circulating DNA-markers in lung cancer: changes in retrotrasposons methylation status in response therapy and during the post-treatment follow-up

Malignant cell transformation is accompanied by two processes of DNA methylation changes

Dynamics of LINE-1 retrotransposon methylation levels in circulating DNA from lung cancer patients undergoing antitumor therapy

Malignant cell transformation is accompanied with abnormal DNA methylation, such as the hypermethylation of certain gene promoters and hypomethylation of retrotransposons. In particular, the hypomethylation of the human-specific family of LINE-1 retrotransposons was observed in lung cancer tissues. It is also known that the circulating DNA (cirDNA) of blood plasma and cell-surface-bound circulating DNA (csb-cirDNA) of cancer patients accumulate tumor-specific aberrantly methylated DNA fragments, which are currently considered to be valuable cancer markers. This work compares LINE-1 retrotransposon methylation patterns in cirDNA of 16 lung cancer patients before and after treatment. CirDNA was isolated from blood plasma, and csb-cirDNA fractions were obtained by successive elution with EDTA-containing phosphate buffered saline and trypsin. Concentrations of methylated LINE-1 region 1 copies (LINE-1-met) were assayed by real-time methylation-specific PCR. LINE-1 methylation levels were normalized to the concentration of LINE-1 region 2, which was independent of the methylation status (LINE-1-Ind). The concentrations of LINE-1-met and LINE-1-Ind in csb-cirDNA of lung cancer patients exhibited correlations before treatment (r = 0.54), after chemotherapy (r = 0.72), and after surgery (r = 0.83) (P 0.05, respectively). These results suggest a need for the further investigation of dynamic changes in levels of LINE-1 methylation depending on the antitumor therapy

Effect of Granulometric Composition of Powder Composition on Geometry of Weld Rolls

The results of the developed industrial technology of surface restoration of corrosion-resistant steels by laser welding are presented. Comparative analysis of microstructure of built-up wear-resistant layer, zone of fusion with base material and diffusion zone at different process conditions of build-up is given. Influence of morphology of particles of filler powder on parametric characteristics of roller produced by laser gas-powder build-up is investigated.Представлены результаты разработанной промышленной технологии восстановления поверхности коррозионностойких сталей методом лазерной наплавки. Приведен сравнительный анализ микроструктуры наплавленного износостойкого слоя, зоны сплавления с материалом основы и диффузионной зоны при разных технологических режимах наплавки. Исследовано влияние морфологии частиц присадочного порошка на параметрические характеристики валика, полученного лазерной газопорошковой наплавкой

Epigenetic «probes» for lung cancer monitoring: LINE-1 methylation pattern in blood- circulating DNA

Malignant cell transformation is accompanied by two processes of DNA methylation changes: promoter hypermethylation of specific genes and hypomethylation of retrotransposons. The composition of circulating DNA (cirDNA) from plasma and cell-surface-bound circulating DNA (csb- cirDNA) was shown earlier to be altered in the blood of cancer patients due to accumulation of tumor- specific aberrantly methylated DNA fragments, which are currently considered valuable cancer markers. The present study compares LINE-1 retrotransposon methylation patterns in plasma cirDNA and csb- cirDNA from 21 untreated lung cancer patients (LC) and 23 healthy donors. Concentrations of methylated LINE-1 region 1 copies (LINE-1met) were assayed by real-time methylation-specific PCR. In order to normalize the LINE-1 methylation level, the LINE-1 region 2 concentration was evaluated, which was independent of the methylation status (LINE-1Ind). The LINE-1met concentration in csb-cirDNA tended to decrease (by a factor of 1.4) in blood from LC patients in comparison to healthy donors (Mann- Whitney test, P=0.16). The LINE-1Ind concentration in csb-cirDNA (methylation-independent) was found to be threefold lower in LC patients and fourfold lower in patients with adenocarcinoma than in healthy donors. That is why, along with the expected decrease in LINE-1met concentration in csb-cirDNA, we recorded an unexpected statistically significant increase of the LINE-1 methylation index determined as (LINE-1met/LINE-1Ind) due to the profound LINE-1Ind decrease. Plasma cirDNA demonstrated no difference in the LINE-1 methylation index (LINE-1met/LINE-1Ind) between LC patients and healthy donors (Mann-Whitney test, P = 0.40). The data obtained agree with our earlier results, which showed that csb-cirDNA was a highly informative material for lung cancer diagnostics

Polarisation dynamics of vector soliton molecules in mode locked fibre laser

Two fundamental laser physics phenomena - dissipative soliton and polarisation of light are recently merged to the concept of vector dissipative soliton (VDS), viz. train of short pulses with specific state of polarisation (SOP) and shape defined by an interplay between anisotropy, gain/loss, dispersion, and nonlinearity. Emergence of VDSs is both of the fundamental scientific interest and is also a promising technique for control of dynamic SOPs important for numerous applications from nano-optics to high capacity fibre optic communications. Using specially designed and developed fast polarimeter, we present here the first experimental results on SOP evolution of vector soliton molecules with periodic polarisation switching between two and three SOPs and superposition of polarisation switching with SOP precessing. The underlying physics presents an interplay between linear and circular birefringence of a laser cavity along with light induced anisotropy caused by polarisation hole burning