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In 2019 September, a sudden flare of the 6.7 GHz methanol maser was observed toward the high-mass young stellar object (HMYSO) G24.33+0.14. This may represent the fourth detection of a transient mass accretion event in an HMYSO after S255IR NIRS3, NGC 6334I-MM1, and G358.93−0.03-MM1. G24.33+0.14 is unique among these sources as it clearly shows a repeating flare with an 8 yr interval. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we observed the millimeter continuum and molecular lines toward G24.33+0.14 in the pre-flare phase in 2016 August (ALMA Cycle 3) and the mid-flare phase in 2019 September (ALMA Cycle 6). We identified three continuum sources in G24.33+0.14, and the brightest source, C1, which is closely associated with the 6.7 GHz maser emission, shows only a marginal increase in flux density with a flux ratio (Cycle 6$/$Cycle 3) of 1.16 ± 0.01, considering an additional absolute flux calibration uncertainty of $10\%$. We identified 26 transitions from 13 molecular species other than methanol, and they exhibit similar levels of flux differences with an average flux ratio of 1.12 ± 0.15. In contrast, eight methanol lines observed in Cycle 6 are brighter than those in Cycle 3 with an average flux ratio of 1.23 ± 0.13, and the higher excitation lines tend to show a larger flux increase. If this systematic increasing trend is real, it would suggest radiative heating close to the central HMYSO due to an accretion event which could expand the size of the emission region and/or change the excitation conditions. Given the low brightness temperatures and small flux changes, most of the methanol emission is likely to be predominantly thermal, except for the 229.759 GHz (8−1–70E) line known as a class I methanol maser. The flux change in the millimeter continuum of G24.33+0.14 is smaller than in S255IR NIRS3 and NGC 6334I-MM1 but is comparable with that in G358.93−0.03-MM1, suggesting different amounts of accreted mass in these events.

Using the deep-level transient spectroscopy and reverse recovery method, the minority carrier lifetime in the base n0-layers of high-voltage GaAs p+–p0–i–n0–n+-diodes grown by the liquid phase epitaxy in argon atmosphere has been estimated before and after irradiation by neutrons with the energy of 1 MeV and the fluence of 1.6 × 1014cm–2. Correlation between the values of the minority carrier lifetime determined by both methods was found. EL2 defects where shown to govern the dynamic switching characteristics of non-irradiated GaAs diodes, while the switching process in the irradiated diodes is determined by the acceptor-like states of defect bands located above the midgap, which are D–states of a three-charged donor. Having been irradiated with neutrons, the diodes revealed a significant decrease in the time of their reverse recovery upon changing the character of the diode switching from the “hard” mode to the “soft” one.

The ATCA, MERLIN and VLA interferometers were used to measure the absolute positions of 35 6.7-GHz methanol masers to subarcsecond or higher accuracy. Our measurements represent essential preparatory data for Very Long Baseline Interferometry, which can provide accurate parallax and proper motion determinations of the star-forming regions harboring the masers. Our data also allow associations to be established with infrared sources at different wavelengths. Our findings support the view that the 6.7 GHz masers are associated with the earliest phases of high-mass star formation.

Context.It is now well established that the strong and widespread 6.7 GHz methanol masers are associated with young high mass stars. A still unsolved question is where in the circumstellar environment the masers arise.

The 1612 MHz hydroxyl maser in circumstellar envelopes has long been thought to be pumped by 34.6 μm photons. Only recently, the Infrared Space Observatory has made possible spectroscopic observations which enable the direct confirmation of this pumping mechanism in a few cases. To look for the presence of this pumping line, we have searched the Infrared Space Observatory Data Archive and found 178 spectra with data around 34.6 μm for 87 galactic 1612 MHz masers. The analysis performed showed that the noise level and the spectral resolution of the spectra are the most important factors affecting the detection of the 34.6 μm absorption line. Only 5 objects from the sample (3 red supergiants and 2 galactic center sources) are found to show clear 34.6 μm absorption (all of them already known) while two additional objects only tentatively show this line. The 3 supergiants show similar pump rates and their masers might be purely radiatively pumped. The pump rates of OH masers in late type stars are found to be about 0.05, only 1/5 of the theoretical value of 0.25 derived by Elitzur (1992). We have also found 16 maser sources which, according to the analysis assuming Elitzur's pump rate, should show the 34.6 μm absorption line but do not. These non-detections can be tentatively explained by far-infrared photon pumping, clumpy nature of the OH masing region or a limb-filling emission effect in the OH shell.

We argue that the interaction of stellar wind with the surface of a circumstellar accretion (or protoplanetary) disk can result in the acceleration of relativistic electrons in an external layer of the disk, and produce synchrotron radiation. Conservative estimates give a total synchrotron luminosity $L_{\rm s}\sim 10^{-5}~L_\odot$for a central star with $\dot M=10^{-6}~M_\odot$yr-1, comparable with the value observed around the TW object in the W3(OH) region.

Using the Haystack Observatory 37-m radio telescope we have undertaken a search for emission in the $2_0{-}3_1$E rotational transition of methanol in its first torsionally excited state ($v\rm _t = 1$) at 44.9 GHz. We examined seven galactic sources – six strong emitters of Class II methanol maser lines and Orion KL, the only source where this line had been previously detected. We confirm (at a level of $5\sigma$) the previous detection and report two new detections – a reliable ($9\sigma$) detection in W3(OH)and a marginal ($3.5\sigma$) detection in NGC 6334F. Upper limits for other sources are presented. Although we did not see obvious signatures of maser amplification in this transition in any source, arguments in favor of weak masing in W3(OH)are presented.

This paper reviews a wide range of questions in astrophysics and cosmology that can be answered by astronomical observations in the far-IR to millimeter wavelength range and which include the formation and evolution of stars and planets, galaxies, and the interstellar medium, the study of black holes, and the development of the cosmological model. These questions are considered in relation to the Millimetron Space Observatory (Spectrum-M project), which is equipped with a 10 m aperture cooled telescope and can operate both as a single-dish telescope and as part of a space-ground very long baseline interferometer.

The characteristics of andalusite, which is a natural raw material used without prior firing, are presented together with physical and service properties of andalusite refractories. The main spheres of application of refractories based on andalusite in ferrous metallurgy are described, namely, in air heaters of blast furnaces, mobile mixers, and hot-metal transfer, steel-casting, and intermediate ladles. Andalusite refractories are also used for auxiliary equipment. Advantages of the use of andalusite refractory materials and articles as compared to other kinds of refractory materials, including bauxite-base refractories, are described.

The process of mullitization of andalusite is reviewed to show that this phase transformation is based on the mechanisms of a pseudomorphism that fixes the grain shape and the chemistry of solid-phase processes. Mullite is oriented in correspondence with the generating crystal of andalusite along the C axis. A single crystal of andalusite transforms into a compound consisting of a mullite single crystal with capillary pores filled with a glass phase saturated with amorphous silica. The capillaries form a network of well-connected tubular pores with a micron cross section, and they are positioned along the C axis common for the newly formed mullite and the original andalusite. About 80% of the glass phase remains in pores of capillaries of the formed mullite. The results of the study were tested in reactions between andalusites of various grain compositions and powder alumina and are now used for fabricating unshaped refractory mixtures with an ultralow content of cement and cement-free mixtures with finely milled andalusite and alumina.

Searches for new sources and regular monitoring of several molecular clouds in the methanol 44-1-30 E transition are in progress since 1988 with the 22 meter radio telescope of the Lebedev Physical Institute. Spectra and several-point maps (when available) of the sources are presented and briefly discussed. Several sources emit both "broad" (a few km/s) and "spike" (≤1 km/s) spectral features. No time variations were detected within the accuracy of the observations. The common procedure of the methanol column density calculations for the "broad" 4-1-30 E features is critically analyzed. It is shown that treating these features as optically thin and "thermal" may lead to an over estimation of the column density by the order of magnitude. The astrophysical nature of the "broad" and "spike" components is discussed.

1.Calculations have been performed of cytidine, N3-methylcytidine, N4-acetylcytidine, and 3,N4-ethenocytidine within the framework of the CNDO/2 method.2.Productive interaction of a phosphate acceptor with the enzyme must take place at several points and, apparently, contacts of the 4-NH2 group and the O2 atom are decisive for RNase A, and those of the N3 and O2 atoms for the RNase ofP. brevicompactum.

We investigate the possibility of interstellar masers in transitions of the methanol isotopomers CH3OD, 13CH3OH and CH318OH, and of CH3SH. The model used, in which masers are pumped through the first and second torsionally excited states by IR radiation, has accounted successfully for the Class II masers in main species methanol, 12CH316OH. Several potential maser candidates are identified for CH3OD, their detectability depending on the enrichment of this species in star‐forming regions. In 13CH3OH and CH318OH the best maser candidates are direct counterparts of the well‐known 6.7‐ and 12.2‐GHz methanol masers, but the lower interstellar abundance of these substituted species means that the expected brightness is greatly reduced. The maser candidates in CH3SH are also weak. By comparing these species we find that the large b‐component of the dipole moment in methanol plays a significant role in its propensity to form masers, as does the strong torsion–rotation interaction due to the light hydroxyl frame. Thus the exceptional brightness of interstellar methanol masers is due to a favourable combination of molecular properties as well as high interstellar abundance.

A study was made of the phagocytic process effected by the macrophages obtained in vitro from the bone marrow or by washing of the peritoneal cavity of guinea pigs. As shwon, the bone marrow histiocytes are a convenient model for studying the macrophageal phagocytosis in vitroCl.butyricum, a saprophytic microorganism, is used as an object for phagocytosis. A natural label in the form of histochemically detectable intracellular polysacharide contained in this organism makes it possible to trace the fate of the phagocytized microbial material and to assess the degree of the phagocytic process's completion. Apart from the aforementioned positive aspects the use of such testmicrobes has also the advantage of their being obligatory anaerobes; therefore, they do not multiply in the tissue culture and do not require for their depression the use of antibiotics, which is not always desirable.

The author conducted a comparative histochemical study of different types of macrophages appearing in normal and experimental conditions. Substances of polysaccharide and lipoidal origin formed in the macrophages as a result of the transformation of phagocytized material (including microbes) may be present in the macro-phages, differeing in genesis and function. These substances may be and are to be differentiated from each other and from the polysaccharides of the cytoplasm proper of the macrophages.

A study was made of the effect of methylation on the chromotropic properties of certain structural elements of the intestinal wall (rabbit appendix) under normal conditions and after previous sulfation. It was found that the cause of the reversibility of natural basophilia due to the presence in the substrate of carboxyl radicals and sulfuric acid polyesters (acid mucopolysaccharides of the intestinal epithelium) was the mechanism of ester linkage formation between the latter and the methyl group. The depression of basophilia occurring after sulfation (and connected with the formation of artificially produced sulfur esters) was reversible and in the nature of a methanolytic desulfation. We discussed the significance of these tests in connection with histological differentiation.

Star formation is thought to be driven by two groups of mechanisms; spontaneous collapse and triggered collapse. Triggered star formation mechanisms further diverge into cloud–cloud collision (CCC), “collect and collapse” (C&C) and shock-induced collapse of pre-existing, gravitationally stable cores, or “radiation driven implosion” (RDI). To evaluate the contributions of these mechanisms and establish whether these processes can occur together within the same star-forming region, we performed mapping observations of radio-frequency ammonia and water maser emission lines in the S235 massive star-forming region. Via spectral analyses of main, hyperfine, and multi-transitional ammonia lines we explored the distribution of temperature and column density in the dense gas in the S235 and S235AB star-forming region. The most remarkable result of the mapping observations is the discovery of high-density gas in inter-core bridges which physically link dense molecular cores that house young proto-stellar clusters. The presence of dense gas implies the potential for future star formation within the system of cores and gas bridges. Cluster formation implies collapse, and the continuous physical links, also seen in re-imaged archival CS and 13CO maps, suggest a common origin to the molecular cores housing these clusters, i.e a structure condensed from a single, larger parent cloud, brought about by the influence of a local expanding H$\,$iiregion. An ammonia absorption feature co-locating with the center of the extended H$\,$iiregion may be attributed to an older gas component left over from the period prior to formation of the H$\,$iiregion. Our observations also detail known and new sites of water maser emission, highlighting regions of active ongoing star formation.

The article considers the verification and validation processes algorithms of the finite element model calculation results of wooden structures joints with the use of glued steel flat rods. The introduction shows the relevance of the determination processes the accordance between numerical and mathematical models and numerical and physical models accepted for calculation. As an example, methods for calculating multicomponent joints of wooden structures on glued steel flat rods pasted into wood are considered, and structural nodes solutions of wooden trusses on these type connections are given. The second paragraph describes the features of finite element models creation for calculating the stress-strain state of the glued joint of flat rods with wood when they are pulled out with rigid nodes in the conjugation zone of finite elements from various materials and when contact surfaces are created in this zone. A mathematical solution of this problem, reduced to the plane deformation problem for finite canonical domains, is considered. An analytic solution of this three-dimensional problem, reduced to the plane deformation problem for finite canonical domains, is considered. The mathematical solution is based on obtaining functions that are biorthogonal to the Papkovich-Fadl eigenfunctions. The calculation results comparison of the stress-strain state of the finite element model of the steel flat rods' glued joint with wood, the analytical solution and experiment are given. On the basis of verification and validation it was shown that the proposed approaches to the construction and calculation of the glued joint of steel flat rods with wood can be reasonably applied to determine the stress-strain state and the design of the wooden structures nodes

We report the result of a systematic methanol observation toward IRAS 19312+1950. The properties of the SiO, H2O, and OH masers of this object are consistent with those of mass-losing evolved stars, but some other properties are difficult to explain in the standard scheme of stellar evolution in its late stage. Interestingly, a tentative detection of radio methanol lines was suggested toward this object by a previous observation. To date, there are no confirmed detections of methanol emission towards evolved stars, so investigation of this possible detection is important to better understand the circumstellar physical/chemical environment of IRAS 19312+1950. In this study, we systematically observed multiple methanol lines of IRAS 19312+1950 in the λ = 3 mm, 7 mm, and 13 mm bands, and detected six lines including four thermal lines and two class I maser lines. We derived basic physical parameters, including kinetic temperature and relative abundances, by fitting a radiative transfer model. According to the derived excitation temperature and line profiles, a spherically expanding outflow lying at the center of the nebulosity is excluded from the possibilities for methanol emission regions. The detection of class I methanol maser emission suggests that a shock region is involved in the system of IRAS 19312+1950. If the central star of IRAS 19312+1950 is an evolved star as suggested in the past, the class I maser detected in the present observation is the first case detected in an interaction region between an evolved star outflow and ambient molecular gas.

This paper reviews a wide range of questions in astrophysics and cosmology that can be answered by astronomical observations in the far-IR to millimeter wavelength range and which include the formation and evolution of stars and planets, galaxies, and the interstellar medium, the study of black holes, and the development of the cosmological model. These questions are considered in relation to the Millimetron Space Observatory (Spectrum-M project), which is equipped with a aperture cooled telescope and can operate both as a single-dish telescope and as part of a space–ground very long baseline interferometer.