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Purpose. To develop a method for calculating a process of graphitizing modification of unsolidificated liquid-solid zone to reduce transcrystallinity of the macrostructure and the amount of cementite in the center of castings. Methodology. The duration of solidification of the castings was determined by the kinetic curves of liquidus, solidus and pouring boundary in coordinates of relative thickness of the solidified metal layer – the parametric criterion of Gulyaev. Findings. A methodology for the process of modification of the axial zone of rolling was developed, the mass and time of adding aluminum were determined according to the amount of liquid-solid phase that remains after the solidification of the working layer. On the example of a rolling roll weighing 1115 kg, 0.488 kg of aluminum was added into liquid-solid zone after the working layer solidified. Movement of aluminum to the front of crystallization is provided by centrifugal forces and adding of aluminum along the height of the roll. Originality. For the first time, the kinetic curves of liquidus, solidus and pouring boundary have been plotted in coordinates of the relative thickness of the solidified metal layer x/R and /R2 – the parametric criterion of Gulyaev for rolled cast iron alloys cooled in chill-sand molds of various sizes. A methodology was developed for calculating the process of aluminum modification of the axial zone of rolling rolls after solidification of the working layer in the barrel which was set at the pouring boundary. The amount of aluminum depends on the remains of the liquid-solid phase. Practical value. Graphitizing modification reduces transcrystallinity of the macrostructure and the amount of cementite in the axial zone of castings. A promising direction for further development is the development of new methods for manufacturing castings due to physical and mechanical effects on the two-phase zone, deoxidation and alloying of the central zones of castings.

Objectives This paper describes the emergence of the scientific study of mindfulness in schools; summarizes findings of experimental research on the impacts of school-based mindfulness programs (SBMPs) on student outcomes in prekindergarten, primary, and secondary school settings (ages 4–18 years); discusses scientific limitations and wider critiques of this work; and offers suggestions for future research. Methods Public data are used to describe the emergence of science on SBMPs, the foci of this research, and the academic disciplines contributing to it. A narrative summary of scientific findings regarding the impacts of SBMPs on students, and critiques of this work, is also presented. Results Research is increasing and is primarily psychological and prevention-oriented. Evidence shows SBMPs can enhance students’ self-regulation abilities, but SBMPs’ impacts on other student outcomes at different ages are equivocal. The current research has significant limitations, and these, alongside wider critiques of the work, suggest important directions for research. Conclusions In the next generation of science, we suggest (a) improving the experimental research; (b) expanding developmental research; and (c) re-envisioning assumptions, theories, and methods in research to go “beyond all splits” towards a non-dualistic and relationally, culturally, contextually, ethically, and developmentally grounded science on mindfulness and compassion for students in schools.

The object of the study were 30 sexually mature eight-month-old female rats, whose average body weight was 0.4 kg. Further calculation of the administration of feed and drugs was performed based on the body weight of the animals.

Cosmogenic radio-nuclei are an important source of background for low-energy neutrino experiments. In Borexino, cosmogenic $$^{11}$$ 11 C decays outnumber solar pep and CNO neutrino events by about ten to one. In order to extract the flux of these two neutrino species, a highly efficient identification of this background is mandatory. We present here the details of the most consolidated strategy, used throughout Borexino solar neutrino measurements. It hinges upon finding the space-time correlations between $$^{11}$$ 11 C decays, the preceding parent muons and the accompanying neutrons. This article describes the working principles and evaluates the performance of this Three-Fold Coincidence (TFC) technique in its two current implementations: a hard-cut and a likelihood-based approach. Both show stable performances throughout Borexino Phases II (2012–2016) and III (2016–2020) data sets, with a $$^{11}$$ 11 C tagging efficiency of $$\sim 90$$ ∼ 90 % and $$\sim $$ ∼ 63–66 % of the exposure surviving the tagging. We present also a novel technique that targets specifically $$^{11}$$ 11 C produced in high-multiplicity during major spallation events. Such $$^{11}$$ 11 C appear as a burst of events, whose space-time correlation can be exploited. Burst identification can be combined with the TFC to obtain about the same tagging efficiency of $$\sim 90\%$$ ∼ 90 % but with a higher fraction of the exposure surviving, in the range of $$\sim $$ ∼ 66–68 %.

Early recognition of the risk of Alzheimer’s disease (AD) onset is a global challenge that requires the development of reliable and affordable screening methods for wide-scale application. Proteomic studies of blood plasma are of particular relevance; however, the currently proposed differentiating markers are poorly consistent. The targeted quantitative multiple reaction monitoring (MRM) assay of the reported candidate biomarkers (CBs) can contribute to the creation of a consistent marker panel. An MRM-MS analysis of 149 nondepleted EDTA–plasma samples (MHRC, Russia) of patients with AD (n = 47), mild cognitive impairment (MCI, n = 36), vascular dementia (n = 8), frontotemporal dementia (n = 15), and an elderly control group (n = 43) was performed using the BAK 125 kit (MRM Proteomics Inc., Canada). Statistical analysis revealed a significant decrease in the levels of afamin, apolipoprotein E, biotinidase, and serum paraoxonase/arylesterase 1 associated with AD. Different training algorithms for machine learning were performed to identify the protein panels and build corresponding classifiers for the AD prognosis. Machine learning revealed 31 proteins that are important for AD differentiation and mostly include reported earlier CBs. The best-performing classifiers reached 80% accuracy, 79.4% sensitivity and 83.6% specificity and were able to assess the risk of developing AD over the next 3 years for patients with MCI. Overall, this study demonstrates the high potential of the MRM approach combined with machine learning to confirm the significance of previously identified CBs and to propose consistent protein marker panels.

Self-heating normal domains in thin superconducting NbTiN nanostrips with the granular structure were characterized via steady-state hysteretic current–voltage characteristics measured at different substrate temperatures. The temperature dependence and the magnitude of the current, which sustains a domain in equilibrium at different voltages, can only be explained with a phonon heat capacity noticeably less than expected for 3D Debye phonons. This reduced heat capacity coincides with the value obtained earlier from magnetoconductance and photoresponse studies of the same films. The rate of heat flow from electrons at a temperature T e to phonons in the substrate at a temperature T B is proportional to ( T e p − T B p ) with the exponent p ≈ 3, which differs from the exponents for heat flows mediated by the electron–phonon interaction or by escaping of 3D Debye phonons via the film/substrate interface. We attribute both findings to the effect of grains on the phonon spectrum of thin NbTiN films. Our findings are significant for understanding the thermal transport in superconducting devices exploiting thin granular films.

This article discusses the issues of improving hot forming technology of aviation glazing parts from organic glass using modern methods of additive technologies, relevance of development and implementation of this technology in production.

There is a lot of scientific papers that consider the efficiency of different container yard’s handling strategies. The methods of assessment vary from abstract mathematical calculations to aposterioric collection and analyses of practical data. This article deals with a new way of stacking strategy’s estimation. It postulates that investigations based on the extrapolation of existing strategies cannot be reliable due to rapid changes in terminals’ environment and restricted amount of data that can be collected within limited periods of the strategies’ application. The hypothesis of the study is that the only method that could provide robust comparative study of container stacking strategies is the simulation modelling. In the same time, any model is only a tool of analyses. The synthesis could be provided only by massive iterations of single simulation experiments with controlled searching procedure in the space of parameters. Consequently, the stress of the simulation study should be put not on the model itself, but on the way how to use it, i.e. on the experiments planning. Only a rationally constructed machine of simulation scenario generation could provide adequate and statistically reliable results. In order to demonstrate the importance of this ‘task setting’ machine, two example strategies are selected for comparison: (1) allocation of containers to slots with the minimum height and (2) stacking of containers in accordance with expected dwell time. It also shows that the objective function has a great impact on the optimal strategy implementation. In the study described in the paper the number of moves requested to select a container is opted as an optimization criterion.

The article describes the problem of the effectiveness of different container stacking strategies, which has been the matter of research in many scientific works. The methods of substantiating the strategies vary from mathematical calculations to practical application. There has been set the task to prove the adequacy of the new container stacking strategy. The application of different strategies for container terminals is found not reliable due to rapid changes of operating conditions and insufficient amount of data that can be collected for the short period of a strategy application. It is proved that the only reliable method that provides the independent proof of the efficiency of container stacking strategies is simulation modelling. Special attention in the studies should be given to planning of the experiments. To compare the strategies it is proposed to use multiple experiments with different parameters of the incoming and outgoing traffic. There is presented a case of comparison of strategies for finding a minimum over the entire stack and stacking containers based on their shelf life. When analyzing the strategies for storing containers it is necessary to determine the optimality criterion, since the attractiveness of a particular strategy will depend on the selected optimized parameter. As a criterion of optimality in the given example, the complexity of the selection of containers is taken, which is determined by the average number of movements required to select one container. It is justified that according to the optimality criterion, the best strategy takes into account the storage periods of containers.

The nuclear medicine phantom development is based on the step by step description of the computational and experimental biological object model. Computational phantoms are used for geometry of the object description and simulate physics of particle interactions with matter, while experimental phantoms are used for quality control tests and standardization of functional research protocols. Common examples are the dosimetry planning of radionuclide therapy and post-therapeutic scintigraphy with 131I. This review provides a list of methods for computational and experimental phantoms. Examples of existing phantoms created for the nuclear medicine tasks are also given.

The container yard is the key element of any modern container terminal. The huge amount of boxes dwelling on the operational areas of the terminals could occupy a lot of space, since one-time storage capacity of the container mega terminal handling over one million TEUs annually is something around 20 000 TEUs. The ecological pressure imposed on modern container terminal does not permit to allocate for this storage large land areas, thus forcing the box stacks grow high. The selection of the individual boxes becomes a complex and time-consuming procedure, demanding a lot of technological resources and deteriorating the service quality. The predicted combinatorial growth of redundant moves needed to clear the access to the individual container is aggravated by the well-known and widely discussed ‘sinking effect’, when containers arrived earlier are gradually covered by the ones arriving afterwards. While the random selection could be adequately assessed by combinatorial methods, the ‘sinking effect’ allows neither intuitive consideration, nor any traditional mathematical means. The only practical way to treat this problem today is in simulation, but the simulation itself causes yet another problem: the problem of model adequacy. This study deals with one possible approach to the problem designated to prove its validity and adequacy, without which the simulation has naught gnoseological value.

At design stages of any sea port development projects one of the key tasks is to estimate the amount of cargo volume to be stored on the port warehouse. The shortage of the warehouse facilities would disrupt port operations and affect the port marketing position, while the surplus capacity would raise the self-cost of the services rendered by the port. Many port developing projects and long years of operational practice have resulted into certain commonly accepted mathematical techniques that enable to assess all main parameters sufficiently accurately. With ever-growing completion between the ports worldwide, to find a delicate balance between the cost and quality becomes a core task behind nearly every aspect of port design activity. The tools that have been used for centuries in port design and development started to lose their adequacy in modern economic and logistic environment. As the response for this challenge the port designers more and more move to simulation models. In the same time, an adequate simulation models need not only accurate and reliable data, but also requests quite long time. Moreover, the models of the kind usually are created ad hoc, reflecting particular features of the primal object under development and forfeiting the generality and universality of analytical models. At beginning stages of port developing one need to have simple and easy tools for the preliminary accession of project parameters, since usually there are several variants and the full-scaled simulation of them is excluded. Still, these tools should be more enhanced sophisticated than common analytical formulae. The main drawback of the formula calculation (streaming computing by the current IT terminology) is they principally deal with deterministic values, while the real worlds is inhibited with the stochastic ones. The study represented here is an attempt to narrow this gap. The area selected to demonstrate the approach is the port warehouse size, regardless of the cargo type handled. In the same time, this technique can be spread on many other port project parameters needed to be assessed.

The single-phase multi-principal-component CoFeMnTiVZr alloy was obtained by rapid solidification and examined by a combination of electrochemical methods and gas-solid reactions. X-ray diffraction and high-resolution transmission electron microscopy analyses reveal a hexagonal Laves-phase structure (type C14). Cyclic voltammetry and electrochemical impedance spectroscopy investigations in the hydrogen absorption/desorption region give insight into the absorption/desorption kinetics and the change in the desorption charge in terms of the applied potential. The thickness of the hydrogen absorption layer obtained by the electrochemical reaction is estimated by high-resolution transmission electron microscopy. The electrochemical hydrogen storage capacity for a given applied voltage is calculated from a series of chronoamperometry and cyclic voltammetry measurements. The selected alloy exhibits good stability for reversible hydrogen absorption and demonstrates a maximum hydrogen capacity of ∼1.9 wt% at room temperature. The amount of hydrogen absorbed in the gas-solid reaction reaches 1.7 wt% at 298 K and 5 MPa, evidencing a good correlation with the electrochemical results.

The earliest phases of star formation are characterised by intense mass accretion from the circumstellar disk to the central star. One group of lowmass young stellar objects, FU Orionis-type stars (FUors) exhibit accretion rate peaks accompanied by bright eruptions in the optical and infrared regime. The occurance of these outbursts might solve the luminosity problem of protostars, play a key role in accumulating the final stellar mass, and have a significant effiect on the parameters of the envelope and the disk. We are performing a systematic investigation of FUors with millimeter interferometry using NOEMA and ALMA to study the outburst events and examine whether FUors represent normal young stars in exceptional times or are unusual objects. The targeted FUors show very diverse circumstellar morphologies with envelope parameters similar to those of both Class I and Class II systems, but their disks are more massive and more compact than T Tauri disks. To shed light onto the process of disk-formation, accretion, and to what role FUors play in low-mass starformation, we require the identification and light curve monitoring of as many of these stars as possible, together with the multi-wavelength and multi-scale mapping of their circumstellar environment.

We have investigated the spectrum of two-dimensional (2D) plasmon polaritons over the full range of magnetic fields. In our study, we investigate a disk-shaped two-dimensional electron system (2DES) with a metallic gate on the backside of the substrate. Importantly, we show that 2D plasmon polaritons hybridize with the TM$_0$ photonic mode of a dielectric waveguide formed by a sample substrate. We have developed a theory for plasmon-polaritons in an infinite 2DES. We find the experimental data to be in good agreement with the developed theory., 7 pages, 4 figures

We report on the study of phonon properties and electron-phonon coupling in thin NbTiN films, which are intensively exploited in superconducting devices. Studied NbTiN films with thicknesses less than 10~nm are disordered with respect to electron transport, the Ioffe-Regel parameter of $k_F l_e = 2.5-3.0$ ($k_F$ is the Fermi wave vector and $l_e$ is the electron mean free path), and inelastic electron-phonon interaction, the product $q_T l_e \ll 1$ ($q_T$ is the wave vector of a thermal phonon). By means of magnetoconductance and photoresponse techniques, we derived the inelastic electron-phonon scattering rate $1/\tau_{e-ph}$ and determined sound velocities and phonon heat capacities. In the temperature range from 12 to 20~K, the scattering rate varies with temperature as $1/\tau_{e-ph}\propto T^{3.45\pm0.05}$; its value extrapolated to 10~K amounts to approximately 16~ps. Making a comparative analysis of our films and other films used in superconducting devices, such as polycrystalline granular NbN and amorphous WSi, we found a systematic reduction of the sound velocity in all these films by about 50\% as compared to the corresponding bulk crystalline materials. A corresponding increase in the phonon heat capacities in all these films is, however, less than the Debye model predicts. We attribute these findings to reduced film dimensionality and film morphology.

The two major challenges in Raman spectroscopy are the low intensity of spontaneous Raman scattering and often accompanying luminescence. We overcome these two issues with a novel fiber-dispersive Raman spectrometer utilizing pulsed excitation and a superconducting nanowire single-photon detector (SNSPD). By exploiting chromatic dispersion in the fiber material, we stretched propagation times of Raman photons and performed correlated measurements in the time domain, where the two emission processes, Raman scattering and luminescence, can be effectively separated. The spectrometer greatly benefits from SNSPD metrics, i.e. broad spectral sensitivity (from UV to near-IR wavelength range) on a single-photon level and high timing resolution (small timing jitter), which outperform those of competing avalanche single-photon detectors. The spectral resolution achievable with a fiber-dispersive spectrometer for the optimized components is estimated to be as good as 3 - 10 cm

The box selectivity in operational stack of container terminal is a quite common and long studied question. The pure random choice is governed by the theory of probability offering some combinatorial estimations. The introduction of operational rules like import/export separation, storage by shipping lines, sorting by rail or truck transportation etc., as well as the most notorious ‘sinking’ effect, i.e. covering of boxes arrived earlier by next cargo parties – all these blur the clear algebraiс picture and lead to appearance of many heuristic outlooks of the problem. A new impetus to this problem in last decades was given by the rapid development of IT, AI and simulation techniques. There are quite many examples of the models described in the scientific publication reflecting many real and arbitrary terminals, which embed very advanced and complicated mechanisms reflecting selected features and strategies. Unfortunately, these models usually are created ad hoc, with some pragmatic objectives and under the demand of closest possible proximity to the simulating objects. There are much less models designated to pure scientific study of the deep inner mechanisms responsible for the primal behavior of the operating container stack, enabling to introduce step by step new rules and restrictions, providing regular proving of every next stage’s adequacy and easy to use. This paper describes one attempt of this kind to create a new theoretical tool to put into the regular toolkit of the container terminal designer. The study starts with mathematical (combinatorial) considerations, proceeds with some restrictions caused by physical and technological characteristics, and ends up with the simulation model, which adequacy is confirmed by practical results.

Relevance. Psychological distress in persons with maxillofacial area fractures are not sufficiently developed in key of their influence on postoperative pain intensity, patients interpersonal sensitivity and emotional reactions. In the context of maxillofacial reconstructive surgery the psychological support of patients is promising direction to improve the condition of patients in postoperative period. The aim: to determine the effect of psychological support on the intensity and additional characteristics of postoperative pain in patients with maxillofacial fractures. Materials and metods. 120 patients with maxillofacial area fractures, undergoing reconstructive surgery at Municipal Clinical Hospital of Emergency and Rapid Care (Zaporizhzhya, Ukraine) were examined. The study was performed on 2 parallel groups, by 60 patients in each. Patients of the main group underwent original model of psychological support and standard postoperative treatment, patients of control group underwent only standard postoperative treatment. Clinical, radiological, psychological and statistical methods were used. Results. The normalization of patient’s psychological response to postoperative pain and rational perception of physical discomfort were found. Conclusion. The original model of psychological support in the postoperative period of reconstructive surgical interventions for maxillofacial fractures reduces the subjective intensity of postoperative pain among the contingent of patients.

In order to address the deleterious effects of poverty and toxic stress on the development of children’s executive function (EF) skills, it is important for researchers to consider interventions that address multiple overlapping family systems. Interventions should consider influences on children’s developing EF skills, including parent stress, household chaos, and the quality of parent-child interactions. One particularly important component of successful EF intervention is the promotion of cognitive reflection. However, common methods of promoting reflection in children (e.g., mindfulness meditation) might not be appropriate in all contexts. This paper outlines a framework for considering the promotion of cognitive reflection within daily family routines. This integration of practices has the potential to improve children’s EF skills as well as other important family outcomes.

Current crowding at bends of superconducting nanowire single-photon detector (SNSPD) is one of the main factors limiting the performance of meander-style detectors with large filling factors. In this paper, we propose a new concept to reduce the influence of the current crowding effect, a so-called variable thickness SNSPD, which is composed of two regions with different thicknesses. A larger thickness of bends in comparison to the thickness of straight nanowire sections locally reduces the current density and reduces the suppression of the critical current caused by current crowding. This allows variable thickness SNSPD to have a higher critical current, an improved detection efficiency, and decreased dark count rate in comparison with a standard uniform thickness SNSPD with an identical geometry and film quality.

Aims. Current star formation research centers the characterization of the physical and chemical properties of massive stars, which are in the process of formation, at the spatial resolution of individual high-mass cores. Methods. We use sub-arcsecond resolution (~0.′′4) observations with the NOrthern Extended Millimeter Array at 1.37 mm to study the dust emission and molecular gas of 18 high-mass star-forming regions. With distances in the range of 0.7−5.5 kpc, this corresponds to spatial scales down to 300−2300 au that are resolved by our observations. We combined the derived physical and chemical properties of individual cores in these regions to estimate their ages. The temperature structures of these regions are determined by fitting the H2CO and CH3CN line emission. The density profiles are inferred from the 1.37 mm continuum visibilities. The column densities of 11 different species are determined by fitting the emission lines with XCLASS. Results. Within the 18 observed regions, we identified 22 individual cores with associated 1.37 mm continuum emission and with a radially decreasing temperature profile. We find an average temperature power-law index of q = 0.4 ± 0.1 and an average density power-law index of p = 2.0 ± 0.2 on scales that are on the order of several 1000 au. Comparing these results with values of p derived from the literature presumes that the density profiles remain unchanged from clump to core scales. The column densities relative to N(C18O) between pairs of dense gas tracers show tight correlations. We applied the physical-chemical model MUlti Stage ChemicaL codE to the derived column densities of each core and find a mean chemical age of ~60 000 yr and an age spread of 20 000−100 000 yr. With this paper, we release all data products of the CORE project. Conclusions. The CORE sample reveals well-constrained density and temperature power-law distributions. Furthermore, we characterized a large variety in molecular richness that can be explained by an age spread that is then confirmed by our physical-chemical modeling. The hot molecular cores show the greatest number of emission lines, but we also find evolved cores at an evolutionary stage in which most molecules are destroyed and, thus, the spectra appear line-poor once again.

We analyze the effect of different types of fluctuations in internal electron energy on the rates of dark and photon counts in straight current-carrying superconducting nanowires. Dark counts appear due to thermal fluctuations in statistically independent cells with the effective size of the order of the coherence length; each count corresponds to an escape from the equilibrium state through an appropriate saddle point. For photon counts, spectral broadening of the deterministic cut off in the spectra of the detection efficiency can be phenomenologically explained by local thermal fluctuations in the electron energy within cells with the same effective volume as for dark counts.

Although an explicit Theory of Mind (ToM) has been found to develop around 4 years of age in Western societies, recent work showing that 4- and 5-year-olds fail modified versions of False Belief tasks as well as seemingly easier True Belief tasks calls into question the robustness of preschoolers’ belief understanding. Some have argued these findings illustrate children’s conceptual limitations in their understanding of belief that are masked by standard False Belief tasks. However, others claim these examples of children’s failure can be explained by pragmatics of the testing situation, rather than conceptual limitations. Given the documented relation between ToM and executive function, an unexamined possibility is that children’s failure can be explained by certain executive demands. In the current study, we examined the relation between typically developing 4- (n = 43) and 5-year-olds’ (n = 42) performance on traditional and modified False Belief tasks, True Belief tasks, and one component of executive functioning - working memory. We found that children performed worse on modified False Belief tasks and True Belief tasks compared to standard 2-option False Belief tasks, and that working memory was related to modified 3-option contents False Belief performance. These results suggest that a fully representational ToM, one that is stable in the context of increased conceptual, executive, and pragmatic demands, may develop later than traditional accounts have assumed.

We have studied the dust density, temperature and velocity distributions of the archetypal massive young stellar object (MYSO) AFGL 2591. Given its high luminosity ($L=2 \times 10^5$ L$_\odot$) and distance ($d=3.3$ kpc), AFGL 2591 has one of the highest $\sqrt{L}/d$ ratio, giving better resolved dust emission than any other MYSO. As such, this paper provides a template on how to use resolved multi-wavelength data and radiative transfer to obtain a well-constrained 2-D axi-symmetric analytic rotating infall model. We show for the first time that the resolved dust continuum emission from Herschel 70 $��$m observations is extended along the outflow direction, whose origin is explained in part from warm dust in the outflow cavity walls. However, the model can only explain the kinematic features from CH$_3$CN observations with unrealistically low stellar masses ($, 34 pages, 22 figures, 15 tables, 4 appendices. Accepted for publication in MNRAS

We report on the inelastic-scattering rate of electrons on phonons and relaxation of electron energy studied by means of magnetoconductance, and photoresponse, respectively, in a series of strongly disordered superconducting NbN films. The studied films with thicknesses in the range from 3 to 33 nm are characterized by different Ioffe-Regel parameters but an almost constant product q_Tl(q_T is the wave vector of thermal phonons and l is the elastic mean free path of electrons). In the temperature range 14-30 K, the electron-phonon scattering rates obey temperature dependencies close to the power law 1/\tau_{e-ph} \sim T^n with the exponents n = 3.2-3.8. We found that in this temperature range \tau_{e-ph} and n of studied films vary weakly with the thickness and square resistance. At 10 K electron-phonon scattering times are in the range 11.9-17.5 ps. The data extracted from magnetoconductance measurements were used to describe the experimental photoresponse with the two-temperature model. For thick films, the photoresponse is reasonably well described without fitting parameters, however, for thinner films, the fit requires a smaller heat capacity of phonons. We attribute this finding to the reduced density of phonon states in thin films at low temperatures. We also show that the estimated Debye temperature in the studied NbN films is noticeably smaller than in bulk material., Comment: 23 pages, 6 figures

The feasibility of contemporary gas-grain astrochemical models depends on the availability of accurate kinetics data, in particular, for surface processes. We study the sensitivity of gas-grain chemical models to the energy barrier Ea of the important surface reaction between some of the most abundant species: C and H2 (surface C + surface H2 = surface CH2). We used the gas-grain code ALCHEMIC to model the time-dependent chemical evolution over a 2D grid of densities (nH: 10^{3} - 10^{12}cm^{-3}) and temperatures (T: 10 - 300 K), assuming UV-dark (Av = 20 mag) and partly UV-irradiated (Av = 3 mag) conditions that are typical of the dense interstellar medium. We considered two values for the energy barrier of the surface reaction, Ea = 2500 K (as originally implemented in the networks) and Ea = 0 K (as measured in the laboratory and computed by quantum chemistry simulations). We find that if the C + H2 = CH2 surface reaction is barrierless, a more rapid conversion of the surface carbon atoms into methane ice occurs. Overproduction of the CHn hydrocarbon ices affects the surface formation of more complex hydrocarbons, cyanides and nitriles, and CS-bearing species at low temperatures < 10-15 K. The surface hydrogenation of CO and hence the synthesis of complex (organic) molecules become affected as well. As a result, important species whose abundances may change by more than a factor of two at 1 Myr include atomic carbon, small mono-carbonic (C1) and di-carbonic (C2) hydrocarbons, CO2, CN, HCN, HNC, HNCO, CS, H2CO, H2CS, CH2CO, and CH3OH (in either gas and/or ice). The abundances of key species, CO, H2O, and N2 as well as O, HCO+, N2H+, NH3, NO, and most of the S-bearing molecules, remain almost unaffected. Further accurate laboratory measurements and quantum chemical calculations of the surface reaction barriers will be crucial to improve the accuracy of astrochemical models., Submitted to Astronomy & Astrophysics (A&A), 9 pages

The article is devoted to the identification of a high-pressure sodium lamp nonlinear model parameters based on neural network technologies. Identification was carried out using a dynamic neural network. The model had 17 parameters based on second order differential equations. As a result, out of 17 parameters, four were selected that accurately reflect the real picture of the model.