Detuning effects in Brillouin ring microresonator laser.

Brillouin lasers, with their unique properties, offer an intriguing solution for many applications, yet bringing their performance to integrated platforms has remained questionable. We present a theoretical framework to describe Brillouin lasing in integrated ring microcavities. Specifically, a general case of a mismatch between the Brillouin shift and the microresonator inter-mode spacing is considered. We show that although the lasing threshold is increased with the frequency detuning, a significant enhancement of the laser power in comparison with the pure resonant interaction could be achieved. Moreover, there is an optimal pump frequency detuning from the resonant mode frequency, when the effect is most pronounced. An increase of the Brillouin threshold with the pump frequency detuning is accompanied by narrowing the pump frequency range available for lasing. Importantly, at the optimal value of the pump frequency detuning when the Brillouin signal is maximal, Brillouin signal noise level is minimal. Analytical results obtained in the steady-state approach are in quantitative agreement with the results of numerical simulations.

Inhibition of Neutrophil Elastase and Cathepsin G As a New Approach to the Treatment of Psoriasis: From Fundamental Biology to Development of New Target-Specific Drugs.

Psoriasis therapy remains an extremely relevant area of modern drug design, due to necessity of adverse reaction reduction, inherent for actual methods of therapy. It was established that two serine proteases-neutrophil elastase 1 (HNE1) and cathepsin G (CatG)-are the key agents in psoriasis development. The collected molecular data for the presented targets form the basis for the molecular modeling strategy for the search for and identification of new target-specific inhibitors. The result of this work is a group of high-priority small-molecule compounds with double-targeted affinity, which are able to suppress the pro-psoriatic processes induced by the considered serine proteases at the initial stage of the disease.

Room-temperature yellow-orange (In,Ga,Al)P-GaP laser diodes grown on (n11) GaAs substrates.

We report room temperature injection lasing in the yellow-orange spectral range (599-605 nm) in (AlxGa1-x)0.5In0.5P-GaAs diodes with 4 layers of tensile-strained InyGa1-yP quantum dot-like insertions. The wafers were grown by metal-organic vapor phase epitaxy side-by-side on (811), (211) and (322) GaAs substrates tilted towards the <111> direction with respect to the (100) surface. Four sheets of GaP-rich quantum barrier insertions were applied to suppress leakage of non-equilibrium electrons from the gain medium. Laser diodes having a threshold current densities of ~7-10 kA/cm2 at room temperature were realized for both (211) and (322) surface orientations at cavity lengths of ~1mm. Emission wavelength at room temperature ~600 nm is shorter by ~8 nm than previously reported. As an opposite example, the devices grown on (811) GaAs substrates did not show lasing at room temperature.

Virtual cavity in distributed Bragg reflectors.

We show theoretically and experimentally that distributed Bragg reflector (DBR) supports a surface electromagnetic wave exhibiting evanescent decay in the air and oscillatory decay in the DBR. The wave exists in TM polarization only. The field extension in the air may reach several wavelengths of light. Once gain medium is introduced into the DBR a novel class of diode lasers, semiconductor optical amplifiers, light-emitting diodes, etc. can be developed allowing a new type of in-plane or near-field light outcoupling. To improve the wavelength stability of the laser diode, a resonant cavity structure can be coupled to the DBR, allowing a coupled state of the cavity mode and the near-field mode. A GaAlAs-based epitaxial structure of a vertical-cavity surface-emitting laser (VCSEL) having an antiwaveguiding cavity and multiple GaInAs quantum wells as an active region was grown and processed as an in-plane Fabry-Pérot resonator with cleaved facets. Windows in the top stripe contact were made to facilitate monitoring of the optical modes. Three types of the optical modes were observed in electroluminescence (EL) studies under high current densities > 1 kA/cm2. Mode A with the longest wavelength is a VCSEL-like mode emitting normal to the surface. Mode B has a shorter wavelength, emitting light at two symmetric lobes tilted with respect to the normal to the surface in the direction parallel to the stripe. Mode C has the shortest wavelength and shifts with a temperature at a rate 0.06 nm/K. Polarization studies reveal predominantly TE emission for modes A and B and purely TM for mode C in agreement with the theory. Spectral position, thermal shift and polarization of mode C confirm it to be a coupled state of the cavity mode and near-field DBR surface-trapped mode.

Electrically pumped InGaAs/GaAs quantum well microdisk lasers directly grown on Si(100) with Ge/GaAs buffer.

In this work we report, to the best of our knowledge, the first quantum well electrically-pumped microdisk lasers monolithically deposited on (001)-oriented Si substrate. The III-V laser structure was epitaxially grown by MOCVD on silicon with an intermediate MBE-grown Ge buffer. Microlasers with an InGaAs/GaAs quantum well active region were tested at room temperature. Under pulsed injection, lasing is achieved in microlasers with diameters of 23, 27, and 31 µm with a minimal threshold current density of 28 kA/cm2. Lasing spectrum is predominantly single-mode with a dominant mode linewidth as narrow as 35 pm.

The Diversity of Parasites in the Chinese Sleeper Perccottus glenii Dybowski 1877 (Actinopterygii: Perciformes) under the Conditions of Large-Scale Range Expansion.

It has been found that the species composition of parasites infesting the Chinese sleeper Perccottus glenii in water bodies from the nonnative part of its range is more depleted. Here, the phylogenetic distances between parasites exceed those in the native part of the range. It has been revealed that parasitological differences between P. glenii populations from the nonnative and native parts of the range, as well as between populations inside the nonnative part, have similar composition and abundance of the host-specific and euryxenous components in the parasitic fauna. It has been shown that these differences are determined by the genesis of sites from which P. glenii is introduced, as well as the local conditions of the recipient water bodies.

Engineering optical properties of a graphene oxide metamaterial assembled in microfluidic channels.

The dense packing of two dimensional flakes by van der Waals forces has enabled the creation of new metamaterials with desirable optical properties. Here we assemble graphene oxide sheets into a three dimensional metamaterial using a microfluidic technique and confirm their ordering via measurements of ellipsometric parameters, polarized optical microscopy, polarized transmission spectroscopy, infrared spectroscopy and scanning electron microscopy. We show that the produced metamaterials demonstrate strong in-plane optical anisotropy (Δn≈0.3 at n≈1.5-1.8) combined with low absorption (k<0.1) and compare them with as-synthesized samples of graphene oxide paper. Our results pave the way for engineered birefringent metamaterials on the basis of two dimensional atomic crystals including graphene and its derivatives.

Mode selection in InAs quantum dot microdisk lasers using focused ion beam technique.

Optically pumped InAs quantum dot microdisk lasers with grooves etched on their surface by a focused ion beam are studied. It is shown that the radial grooves, depending on their length, suppress the lasing of specific radial modes of the microdisk. Total suppression of all radial modes, except for the fundamental radial one, is also demonstrated. The comparison of laser spectra measured at 78 K before and after ion beam etching for a microdisk of 8 µm in diameter shows a sixfold increase of mode spacing, from 2.5 to 15.5 nm, without a significant decrease of the dominant mode quality factor. Numerical simulations are in good agreement with experimental results.

Hybrid InGaAs quantum well-dots nanostructures for light-emitting and photo-voltaic applications.

Hybrid quantum well-dots (QWD) nanostructures have been formed by deposition of 7-10 monolayers of In0.4Ga0.6As on a vicinal GaAs surface using metal-organic chemical vapor deposition. Transmission electron microscopy, photoluminescence and photocurrent analysis have shown that such structures represent quantum wells comprising three-dimensional (quantum dot-like) regions of two kinds. At least 20 QWD layers can be deposited defect-free providing high gain/absorption in the 0.9-1.1 spectral interval. Use of QWD media in a GaAs solar cell resulted in a photocurrent increment of 3.7 mA cm(-2) for the terrestrial spectrum and by 4.1 mA cm(-2) for the space spectrum. Diode lasers based on QWD emitting around 1.1 µm revealed high saturated gain and low transparency current density of about 15 cm(-1) and 37 A cm(-2) per layer, respectively.

[The Battle of Stalingrad in the memoirs of the military physician].

The article is devoted to the first publication of reminiscences of former military physician Alexander Zhukov (1919-2014), concerning the everyday work of military physicians in the one of the most crucial periods of the Great Patriotic War-the Battle of Stalingrad, in which the author took part from the very first to the last day.

Control of emission spectra in quantum dot microdisk/microring lasers.

Focused ion beam is applied to quantum dot based microresonators to form pits or groove on their surface. The emission spectra of the resonators based lasers are significantly thinned out after the ion beam milling, and one or two modes become dominant instead of a group of modes having comparable intensities. The linewidth of the lasing mode is kept unchanged, whereas the lasing threshold demonstrates an insignificant growth.

[Variation trends in the parasite communities of the Chinese sleeper Perccottus glenii (Actinopterygii: Odontobutidae) in its native habitat].

The diversity of parasite communities in the Chinese sleeper Perccottus glenii, at the level of single specimens and populations, is manifested through three components: the number of species, the evenness of their abundance, and the taxonomic diversity. Variations in the diversity depend on the local characteristics of water bodies, as well as the sexual and dimensional factors of the host. This study was performed in four water bodies of the Russian Far East (Primorskii krai and Sakhalin Island).

[Ways of improving the efficacy of preoperative preparation in patients with acute intestinal obstruction].

The comparative assessment of preoperative fluid therapy was made in 56 patients with acute intestinal obstruction. Parameters of central hemodynamics, the intra-abdominal pressure and water sectors of organism were investigated. The fluid therapy was conducted during 3 hours and included Tetraspan and Sterofundin on average 615 ml and 1585 ml, respectively. It was shown, that the fluid therapy facilitated to the elimination of water-electrolytic and hemodynamic shifts and to some extent it improved the outcomes of surgical treatment.

Picoflare jets power the solar wind emerging from a coronal hole on the Sun.

Coronal holes are areas on the Sun with open magnetic field lines. They are a source region of the solar wind, but how the wind emerges from coronal holes is not known. We observed a coronal hole using the Extreme Ultraviolet Imager on the Solar Orbiter spacecraft. We identified jets on scales of a few hundred kilometers, which last 20 to 100 seconds and reach speeds of ~100 kilometers per second. The jets are powered by magnetic reconnection and have kinetic energy in the picoflare range. They are intermittent but widespread within the observed coronal hole. We suggest that such picoflare jets could produce enough high-temperature plasma to sustain the solar wind and that the wind emerges from coronal holes as a highly intermittent outflow at small scales.

Ultra-high-resolution observations of persistent null-point reconnection in the solar corona.

Magnetic reconnection is a key mechanism involved in solar eruptions and is also a prime possibility to heat the low corona to millions of degrees. Here, we present ultra-high-resolution extreme ultraviolet observations of persistent null-point reconnection in the corona at a scale of about 390 km over one hour observations of the Extreme-Ultraviolet Imager on board Solar Orbiter spacecraft. The observations show formation of a null-point configuration above a minor positive polarity embedded within a region of dominant negative polarity near a sunspot. The gentle phase of the persistent null-point reconnection is evidenced by sustained point-like high-temperature plasma (about 10 MK) near the null-point and constant outflow blobs not only along the outer spine but also along the fan surface. The blobs appear at a higher frequency than previously observed with an average velocity of about 80 km s-1 and life-times of about 40 s. The null-point reconnection also occurs explosively but only for 4 minutes, its coupling with a mini-filament eruption generates a spiral jet. These results suggest that magnetic reconnection, at previously unresolved scales, proceeds continually in a gentle and/or explosive way to persistently transfer mass and energy to the overlying corona.

Magnetoelastic contribution in domain wall propagation of micrometric wires.

We report on studies of domain wall propagation of magnetically-bistable Fe-Co-rich microwires paying attention on the effect of applied and internal stresses. We measured magnetic domain propagation in various magnetic Fe-Co-rich amorphous microwires with metallic nucleus diameters (from 2.8 microm to 18 microm) using Sixtus Tonks-like experiments. We found that application of applied stresses and increasing of internal stresses result in decreasing of domain wall (DW) velocity. We assume that in order to achieve higher DW propagation velocity at the same magnetic field and enhanced DW mobility, special attention should be paid to the decrease of magnetoelastic energy.

[Primary hyperparathyroidism in oncological practice].

In the period from 1999 till 2009 there were 18 patients (14 women and 4 men) with adenomas of the parathyroid gland (PTG). Solitary lesions of the bones were diagnosed in 12 of them, 6 patients had multiple lesions. In 5 patients bone lesions were combined with nephrolithiasis and cholelithiasis. Operations resulted in osteodystrophy, normalization of hormonal and biochemical indices. One adenoma of PTG was found in 17 patients, in one woman there were two adenomas on both sides of the trachea, but they were diagnosed not at once. Reoperation gave recovery of the patient.

Preclinical efficacy investigation of human neutrophil elastase inhibitor sivelestat in animal model of psoriasis.

Background: Psoriasis is a chronic immune-mediated inflammatory skin disease manifested by an increased rate of keratinocyte division. Currently, it has been established that the cytokines of the IL-36 family play a significant role in the initiation and regulation of the inflammatory process in psoriasis. The IL-36 cytokine found in skin is inactive and its activation requires proteolytic processing that may occur via the involvement of neutrophil serine proteases such as human neutrophil elastase (HNE). The localization of these enzymes in the upper layers of the epidermis suggests that topical application of HNE inhibitors could be efficacious in the treatment of psoriasis. Sivelestat is an HNE inhibitor developed for systemic use towards the treatment of acute respiratory failure. Aim: The present study focussed on the investigation of the effects of sivelestat formulated for topical use, in the imiquimod-induced model of psoriasis in mice. Methods: The psoriasis-like state was induced by application of imiquimod (Aldara®) 5% cream to mouse shaven skin. A group of 40 inbred mice of the BALB/c strain randomized into 4 groups of 10 was used in the experiment: Group 1 - no therapy (control), Group 2 - ointment (Vaseline) containing 1% sivelestat, Group 3 - cream (lanoline + olive oil + water in equal proportions) containing 1% sivelestat, Group 4 - 1% betamethasone dipropionate. Dermatological assessment of skin lesions was performed by means of the PASI method (mPASI), as well as histological and immunohistochemical evaluation. Results: Based on the evaluation of efficacy manifestations, it was established that the total mPASI index value decreased by 50% during therapy with sivelestat cream and by 36% during therapy with sivelestat ointment. Histological study revealed that the epidermal thickness in groups that underwent therapy was 2.4-3.6 times lower compared to the control group. Immunohistochemical study of the skin indicated that following sivelestat treatment, the quantity of CD3+cells in the skin was 1.8-2.2 times lower, and the level of proliferative activity (Ki-67+cells) was 2.3-2.9 lower compared to the non-therapy group. In contrast to topical corticosteroids where the more pronounced anti-inflammatory effect is typically seen with ointment formulations, with sivelestat we observed an opposite effect. The reasons for that reversal remain unclear. Conclusion: Based on the results obtained using the animal model of imiquimod-induced psoriasis, it was established that the HNE inhibitor sivelestat demonstrated efficacy comparable to that of a strong topical glucocorticoid steroidal drug (betamethasone dipropionate 1%). Significant resolution of skin lesions, reduction of epidermal thickness, diminishing of the skin infiltration with T-lymphocytes and normalization of the cell division rate in epidermis and dermis were evident. Thus, suppression of IL-36 mediated inflammation activity in the skin by topical application of a HNE inhibitor represents a promising new direction in the treatment of psoriasis. Certainly, HNE has other targets; thus, molecular studies could be subject of future experiments beyond the scope of the present study.

Modified Polyethylene Foam for Critical Environments.

One of the most important priorities for all countries with property beyond the Arctic Circle and territories located in permafrost areas is the development of special construction technologies and systems. The required conditions are met by insulation systems based on seamless insulation shells made of polyethylene foam. The study of the strength and performance properties of polyethylene foam and its combinability was carried out according to standard methods and using the methods of experimental design and the analytical processing of the results. The change in material properties at negative temperatures was determined based on the results of climatic tests, followed by an evaluation of creep under load. The evaluation of the effectiveness of the design solutions was carried out using special computer programs. It was found that the performance characteristics of products made of polyethylene foam (rolls, mats) meet the requirements for insulation materials used at temperatures down to -60 °C. The resulting material is moderately combustible, which must be taken into account when developing recommendations for its use in insulation systems. A nomogram has been developed that makes it possible to predict the properties of a material and solve formulation problems. Insulation systems were developed, and a visualisation of the thermal fields of the insulation systems of the external walls and ceilings of a building was carried out.

[Morphological features of the gastric mucosa capillary network in patients with portal hypertension].

The pathogenesis of portal hypertension (PH) involves venous congestion with gastric mucosal capillary dilatation. The formation of new blood vessels, as was shown in experimental models of PH, is pathological hallmark of PH. Generation of new blood vessels is stimulated by vascular endothelial growth factor (VEGF), the regulator of angiogenesis. The aim of the study was to investigate changes in gastric microvessels in patients with liver cirrhosis complicated with PH in different stages, and the factors influencing the development of portal hypertensive gastropathy. We studied the relation between gastric mucosal capillary parameters, measured morphometrically, and endoscopic appearances in 56 patients with PH. The gastric biopsy was obtained from antrum and corpus of the stomach. We determined expression and localization of Fit-1 receptor for VEGF in human gastric mucosa by immunohistochemistry. Mucosal capillary network assessed on histological sections immunostained for CD34, a specific marker for endothelial cells and revealed proliferating endothelial cells by Ki-67 antibodies. Nicon CP 995 camera and digital image analyzing system (DMI-1) was used for morphometry. The number, size and relative volume of vessels in gastric mucosa were evaluated. Helicobacter pillory-positive patients were excluded from study. The number of vessels in gastric mucosa was significantly higher in groups with PH (p < 0.05) compared with patients without PH. The mean size of vessels in gastric mucosa was decreased in patients with PH (212 +/- 20 vs 282 +/- 25 mkm2, p < 0.05) in atrum and (155 +/- 12 vs 198 +/- 13 mkm2, p < 0.039) in corpus. The majority of the vessels were presented by newly formed small sized capillaries. Meanwhile the relative volume of vessels in gastric mucosa was not changed significantly in groups with PH. These observations have not supported the view that PH is usually associated with a prominent dilatation of gastric mucosal capillaries. Our data have shown intensifying of neoangiogenesis in human gastric mucosa at PH. The anti-angiogenic therapeutic approach could be taken into consideration for patients suffering from PH.