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We present the preliminary results of experimental studies on hydrogen production through methane pyrolysis. Based on the analytical review, the technology of methane pyrolysis in the plasma of a microwave discharge was chosen. To implement this method, an installation for applied research PM-6 was developed, and experimental data on the possibility of producing hydrogen was obtained. The methods of mass spectrometry and optical emission spectrometry were used to analyze the products of the methane decomposition reaction. It has been established that at a microwave forward power of 0.6 kW, plasma pyrolysis of methane occurs with the formation of hydrogen, carbon, and hydrocarbons. Preliminary calculations of methane conversion, as a result of the conducted studies, showed a hydrogen selectivity of 4–5%. The developed installation and the applied method are under modernization at the present time.

This paper presents the results of the experimental studies of the helium plasma interaction with a surface carbide layer of tungsten. The experiments were carried out on a plasma beam installation (PBI) at a constant energy of incoming ions of 2 keV and at a surface temperature of the tungsten carbide layer of ~905 and ~1750 ℃. The local parameters (Te, n0) of the helium plasma were evaluated using the probe method and spectrometric analysis of the plasma composition. The helium plasma irradiated two types of the carbide layer on the tungsten surface, WC and W2C. The mechanisms of changing the tungsten surface morphology in the result of the plasma irradiation have been described. The study of the surface structure of the tungsten samples with a carbide layer of two types (WC, W2C) after the exposure to the helium plasma has revealed two different types of the formation of helium bubbles and changes in the surface morphology. The physical mechanism of the formation of helium bubbles consists in the capture of helium atoms by the thermal vacancies generated at high temperature by the material surface. However, with a significant increase in temperature to 1750 ℃, the formation of the bubbles was no longer observed and the sample surface had a developed coral-like structure with crystallographically oriented grains.

Tungsten was chosen as the plasma facing material (PFM) of the ITER divertor. However, graphite and carbon-graphite materials are used as PFM in some research thermonuclear facilities, including the Kazakhstan materials science tokamak. This circumstance determines the interest in continuing the study of the formation of mixed layers under plasma irradiation. This article is devoted to the study of the effect of preliminary recrystallization annealing on the carbidization of the tungsten surface in a beam-plasma discharge (BPD), which is one of the ways to simulate the peripheral plasma of a tokamak. Experiments on preliminary isochoric and isothermal annealing of tungsten samples were carried out in the mode of direct heating of tungsten samples by an electron beam. The carbidization of tungsten samples after annealing was carried out in a methane atmosphere in the BPD at a temperature of 1000 ℃ for a duration of 3600 s. Optical microscopy (OM) and X-ray diffraction were used to analyze the structure of the tungsten surface. It has been established that differences in the structure arising during recrystallization annealing affect the transfer of carbon atoms in the near-surface area of tungsten and the formation of tungsten carbides (WC or W2C).

Previously, the analysis of atomic force microscopy (AFM) images allowed us to distinguish normal from cancerous/precancerous human epithelial cervical cells using only the fractal dimension parameter. High-resolution maps of adhesion between the AFM probe and the cell surface were used in that study. However, the separation of cancerous and precancerous cells was rather poor (the area under the curve (AUC) was only 0.79, whereas the accuracy, sensitivity, and specificity were 74%, 58%, and 84%, respectively). At the same time, the separation between premalignant and malignant cells is the most significant from a clinical point of view. Here, we show that the introduction of machine learning methods for the analysis of adhesion maps allows us to distinguish precancerous and cancerous cervical cells with rather good precision (AUC, accuracy, sensitivity, and specificity are 0.93, 83%, 92%, and 78%, respectively). Substantial improvement in sensitivity is significant because of the unmet need in clinical practice to improve the screening of cervical cancer (a relatively low specificity can be compensated by combining this approach with other currently existing screening methods). The random forest decision tree algorithm was utilized in this study. The analysis was carried out using the data of six precancerous primary cell lines and six cancerous primary cell lines, each derived from different humans. The robustness of the classification was verified using K-fold cross-validation (K = 500). The results are statistically significant at p < 0.0001. Statistical significance was determined using the random shuffle method as a control.

We describe our first attempt to systematically simulate the solar wind during different phases of the last solar cycle with the Alfvén Wave Solar atmosphere Model (AWSoM) developed at the University of Michigan. Key to this study is the determination of the optimal values of one of the most important input parameters of the model, the Poynting flux parameter, which prescribes the energy flux passing through the chromospheric boundary of the model in the form of Alfvén wave turbulence. It is found that the optimal value of the Poynting flux parameter is correlated with the area of the open magnetic field regions with the Spearman’s correlation coefficient of 0.96 and anticorrelated with the average unsigned radial component of the magnetic field with the Spearman’s correlation coefficient of −0.91. Moreover, the Poynting flux in the open field regions is approximately constant in the last solar cycle, which needs to be validated with observations and can shed light on how Alfvén wave turbulence accelerates the solar wind during different phases of the solar cycle. Our results can also be used to set the Poynting flux parameter for real-time solar wind simulations with AWSoM.

Here we address an important roadblock that prevents the use of bright fluorescent nanoparticles as individual ratiometric sensors: the possible variation of fluorescence spectra between individual nanoparticles. Ratiometric measurements using florescent dyes have shown their utility in measuring the spatial distribution of temperature, acidity, and concentration of various ions. However, the dyes have a serious limitation in their use as sensors; namely, their fluorescent spectra can change due to interactions with the surrounding dye. Encapsulation of the d, e in a porous material can solve this issue. Recently, we demonstrated the use of ultrabright nanoporous silica nanoparticles (UNSNP) to measure temperature and acidity. The particles have at least two kinds of encapsulated dyes. Ultrahigh brightness of the particles allows measuring of the signal of interest at the single particle level. However, it raises the problem of spectral variation between particles, which is impossible to control at the nanoscale. Here, we study spectral variations between the UNSNP which have two different encapsulated dyes: rhodamine R6G and RB. The dyes can be used to measure temperature. We synthesized these particles using three different ratios of the dyes. We measured the spectra of individual nanoparticles and compared them with simulations. We observed a rather small variation of fluorescence spectra between individual UNSNP, and the spectra were in very good agreement with the results of our simulations. Thus, one can conclude that individual UNSNP can be used as effective ratiometric sensors.

We explore the performance of the Alfvén Wave Solar atmosphere Model with near-real-time (NRT) synoptic maps of the photospheric vector magnetic field. These maps, produced by assimilating data from the Helioseismic Magnetic Imager (HMI) on board the Solar Dynamics Observatory, use a different method developed at the National Solar Observatory (NSO) to provide a near contemporaneous source of data to drive numerical models. Here, we apply these NSO-HMI-NRT maps to simulate three full Carrington rotations: 2107.69 (centered on the 2011 March 7 20:12 CME event), 2123.5 (centered on 2012 May 11), and 2219.12 (centered on the 2019 July 2 solar eclipse), which together cover various activity levels for solar cycle 24. We show the simulation results, which reproduce both extreme ultraviolet emission from the low corona while simultaneously matching in situ observations at 1 au as well as quantify the total unsigned open magnetic flux from these maps.

It has been recently demonstrated that atomic force microscopy (AFM) allows for the rather precise identification of malignancy in bladder and cervical cells. Furthermore, an example of human colorectal epithelial cells imaged in AFM Ringing mode has demonstrated the ability to distinguish cells with varying cancer aggressiveness with the help of machine learning (ML). The previously used ML methods analyzed the entire cell image. The problem with such an approach is the lack of information about which features of the cell surface are associated with a high degree of aggressiveness of the cells. Here we suggest a machine-learning approach to overcome this problem. Our approach identifies specific geometrical regions on the cell surface that are critical for classifying cells as highly or lowly aggressive. Such localization gives a path to colocalize the newly identified features with possible clustering of specific molecules identified via standard bio-fluorescence imaging. The biological interpretation of the obtained information is discussed.

A novel method based on atomic force microscopy (AFM) working in Ringing mode (RM) to distinguish between two similar human colon epithelial cancer cell lines that exhibit different degrees of neoplastic aggressiveness is reported on. The classification accuracy in identifying the cell line based on the images of a single cell can be as high as 94% (the area under the receiver operating characteristic [ROC] curve is 0.99). Comparing the accuracy using the RM and the regular imaging channels, it is seen that the RM channels are responsible for the high accuracy. The cells are also studied with a traditional AFM indentation method, which gives information about cell mechanics and the pericellular coat. Although a statistically significant difference between the two cell lines is also seen in the indentation method, it provides the accuracy of identifying the cell line at the single‐cell level less than 68% (the area under the ROC curve is 0.73). Thus, AFM cell imaging is substantially more accurate in identifying the cell phenotype than the traditional AFM indentation method. All the obtained cell data are collected on fixed cells and analyzed using machine learning methods. The biophysical reasons for the observed classification are discussed.

Characterization data of fluorescent nanoparticles made of cellulose acetate (CA-dots) are shown. The data in this article accompanies the research article “Ultrabright fluorescent cellulose acetate nanoparticles for imaging tumors through systemic and topical applications” [1]. The measurements and calculation of brightness of individual CA-dots are presented. The description of conjugation procedure Pluronic F127-Folic Acid copolymer and folic acid is shown. Identification of composition of CA dots using Raman and absorbance spectroscopy is demonstrated. The methods for image analysis of efficiency of CA-dot targeting of epithelial tumors xenografted in zebrafish is presented.

Using an artificial neural network (ANN), the values of the antiradical potential of 1315 items of food and agricultural raw materials were calculated. We used an ANN with the structure of a “multilayer perceptron” (MLP) and with the hyberbolic tangent (Tanh) as an activation function. Values reported in the United States Food and Nutrient Database for Dietary Studies (FNDDS) were taken as input to the analysis. When training the ANN, 60 parameters were used, such as the content of plastic substances, food calories, the amount of mineral components, vitamins, the composition of fatty acids and additional substances presented in this database. The analysis revealed correlations, namely, a direct relationship between the value of the antiradical potential (ARP) of food and the concentration of dietary fiber (r = 0.539) and a negative correlation between the value of ARP and the total calorie content of food (r = −0.432) at a significance level of p < 0.001 for both values. The average ARP value for 10 product groups within the 95% CI (confidence interval) was ≈23–28 equivalents (in terms of ascorbic acid) per 1 g of dry matter. The study also evaluated the range of average values of the daily recommended intake of food components (according to Food and Agriculture Organization—FAO, World Health Organization—WHO, Russia and the USA), which within the 95% CI, amounted to 23.41–28.98 equivalents per 1 g of dry weight. Based on the results of the study, it was found that the predicted ARP values depend not only on the type of raw materials and the method of their processing, but also on a number of other environmental and technological factors that make it difficult to obtain accurate values.

The paper considers a method of tungsten surface carbidization using a beam-plasma discharge (BPD), which was implemented in a plasma-beam installation (PBI). The advantage of this method is to create conditions for chemical reactions and physical processes as close as possible to those possible in thermonuclear installations. The BPD makes it possible to generate plasma using different working gases. Methane was used as a plasma-forming gas. The working gas pressure in a chamber was (1,3–1,4)·10 ^–1 Pa. The temperature dependence of the carbidized layer formation on the tungsten surface under plasma irradiation was determined in the temperature range of 700 °C–1700 °C. The formation of tungsten carbides in surface layers was confirmed by SEM and x-ray diffraction analysis. It was found that interaction between tungsten and methane in a wide temperature range can proceed with simultaneous or sequential formation of the carbide phases W _2 C and WC.

The paper presents a new mathematical model of TCP (Transmission Control Protocol) link functioning in a heterogeneous (wired/wireless) channel. It represents a controllable, partially observable stochastic dynamic system. The system state describes the status of the modeled TCP link and expresses it via an unobservable controllable MJP (Markov jump process) with finite-state space. Observations are formed by low-frequency counting processes of packet losses and timeouts and a high-frequency compound Poisson process of packet acknowledgments. The information transmission through the TCP-equipped channel is considered a stochastic control problem with incomplete information. The main idea to solve it is to impose the separation principle on the problem. The paper proposes a mathematical framework and algorithmic support to implement the solution. It includes a solution to the stochastic control problem with complete information, a diffusion approximation of the high-frequency observations, a solution to the MJP state filtering problem given the observations with multiplicative noises, and a numerical scheme of the filtering algorithm. The paper also contains the results of a comparative study of the proposed state-based congestion control algorithm with the contemporary TCP versions: Illinois, CUBIC, Compound, and BBR (Bottleneck Bandwidth and RTT).

The mesoporous nature of silica nanoparticles provides a novel platform for the development of ultrabright fluorescent particles, which have organic molecular fluorescent dyes physically encapsulated inside the silica pores. The close proximity of the dye molecules, which is possible without fluorescence quenching, gives an advantage of building sensors using FRET coupling between the encapsulated dye molecules. Here we present the use of this approach to demonstrate the assembly of ultrabright fluorescent ratiometric sensors capable of simultaneous acidity (pH) and temperature measurements. FRET pairs of the temperature-responsive, pH-sensitive and reference dyes are physically encapsulated inside the silica matrix of ~50 nm particles. We demonstrate that the particles can be used to measure both the temperature in the biologically relevant range (20 to 50 °C) and pH within 4 to 7 range with the error (mean absolute deviation) of 0.54 °C and 0.09, respectively. Stability of the sensor is demonstrated. The sensitivity of the sensor ranges within 0.2–3% °C−1 for the measurements of temperature and 2–6% pH−1 for acidity.

Fluorescent tagging is a popular method in biomedical research. Using multiple taggants of different but resolvable fluorescent spectra simultaneously (multiplexing), it is possible to obtain more comprehensive and faster information about various biochemical reactions and diseases, for example, in the method of flow cytometry. Here we report on a first demonstration of the synthesis of ultrabright fluorescent silica nanoporous nanoparticles (Star-dots), which have a large number of complex fluorescence spectra suitable for multiplexed applications. The spectra are obtained via simple physical mixing of different commercially available fluorescent dyes in a synthesizing bath. The resulting particles contain dye molecules encapsulated inside of cylindrical nanochannels of the silica matrix. The distance between the dye molecules is sufficiently small to attain Forster resonance energy transfer (FRET) coupling within a portion of the encapsulated dye molecules. As a result, one can have particles of multiple spectra that can be excited with just one wavelength. We show this for the mixing of five, three, and two dyes. Furthermore, the dyes can be mixed inside of particles in different proportions. This brings another dimension in the complexity of the obtained spectra and makes the number of different resolvable spectra practically unlimited. We demonstrate that the spectra obtained by different mixing of just two dyes inside of each particle can be easily distinguished by using a linear decomposition method. As a practical example, the errors of demultiplexing are measured when sets of a hundred particles are used for tagging.

The paper is devoted to the optimal state filtering of the finite-state Markov jump processes, given indirect continuous-time observations corrupted by Wiener noise. The crucial feature is that the observation noise intensity is a function of the estimated state, which breaks forthright filtering approaches based on the passage to the innovation process and Girsanov’s measure change. We propose an equivalent observation transform, which allows usage of the classical nonlinear filtering framework. We obtain the optimal estimate as a solution to the discrete–continuous stochastic differential system with both continuous and counting processes on the right-hand side. For effective computer realization, we present a new class of numerical algorithms based on the exact solution to the optimal filtering given the time-discretized observation. The proposed estimate approximations are stable, i.e., have non-negative components and satisfy the normalization condition. We prove the assertions characterizing the approximation accuracy depending on the observation system parameters, time discretization step, the maximal number of allowed state transitions, and the applied scheme of numerical integration.

Our review recognizes 15 species of the integripennis species group of Geocharidius from Nuclear Central America, include three species previously described (G. gimlii Erwin, G. integripennis (Bates) and G. zullinii Vigna Taglianti) and 12 described here as new. They are: G. andersoni sp. n. (type locality: Chiapas, Chiapas Highlands, Cerro Huitepec) and G. vignatagliantii sp. n. (type locality: Chiapas, Motozintla, Sierra Madre de Chiapas, Benito Juárez) from Mexico; G. antigua sp. n. (type locality: Sacatepéquez, 5 km SE of Antigua), G. balini sp. n. (type locality: Suchitepéquez, 4 km S of Volcan Atitlán), G. erwini sp. n. (type locality: Quiché Department, 7 km NE of Los Encuentros), G. jalapensis sp. n. (type locality: Jalapa Department, 4 km E of Mataquescuintla), G. longinoi, sp. n. (type locality: El Progreso Department, Cerro Pinalón), and G. minimus sp. n. (type locality: Sacatepéquez Department, 5 km SE of Antigua) from Guatemala; and G. celaquensis sp. n. (type locality: Lempira Department, Celaque National Park), G. comayaguanus sp. n. (type locality: Comayagua Department, 18 km ENE of Comayagua), G. disjunctus sp. n. (type locality: Francisco Morazán, La Tigra National Park), and G. lencanus sp. n. (type locality: Lempira Department, Celaque National Park) from Honduras. For all members of the group, adult structural characters, including male and female genitalia, are described, and a taxonomic key for all members of the integripennis species group is presented based on these characters. Behavioral and biogeographical aspects of speciation in the group are discussed, based on the morphological analysis. In all cases of sympatry, pairs of closely related species show greater differences in sizes than pairs of more remotely related species. Integripennis group species occupy six different montane areas at elevations above 1300m, with no species shared among them. Major faunal barriers in the region limiting present species distributions include the Motagua Fault Zone and a gap between the Guatemalan Cordillera volcanic chain and the Honduran Interior Highlands no higher than 900m in elevation. Highest species diversity is in the Guatematan Cordillera (six species), second highest in the Honduran Interior Highlands area (four species).

The Texas fauna of the genus Anillinus Casey, 1918 includes three previously described species (A. affabilis (Brues), 1902, A. depressus (Jeannel), 1963 and A. sinuatus (Jeannel), 1963) and four new species here described: A. acutipennis Sokolov & Reddell sp. n. (type locality: Fort Hood area, Bell County, Texas); A. comalensis Sokolov & Kavanaugh sp. n. (type locality: 7 miles W of New Braunfels, Comal County, Texas); A. forthoodensis Sokolov & Reddell sp. n. (type locality: Fort Hood area, Bell County, Texas); A. wisemanensis Sokolov & Kavanaugh sp. n. (type locality: Wiseman Sink, Hays County, Texas). A key for identification of adults of these species is provided. The fauna includes both soil- and cave-inhabiting species restricted to the Balcones Fault Zone and Lampasas Cut Plain and adjacent areas underlain by the Edwards-Trinity Aquifer. Based on morphological and distributional data, we hypothesize that four lineages of endogean Anillinus species extended their geographical ranges from a source area in the Ouachita-Ozark Mountains to the Balconian region in central Texas. There the cavernous Edwards-Trinity aquifer system provided an excellent refugium as the regional climate in the late Tertiary and early Quaternary became increasingly drier, rendering life at the surface nearly impossible for small, litter-inhabiting arthropods. Isolated within the Edwards-Trinity aquifer system, these anilline lineages subsequently differentiated, accounting for the currently known diversity. The paucity of specimens and difficulty in collecting them suggest that additional undiscovered species remain to be found in the region.

One new genus and eight new species of anilline carabids are described from southern Mexico. The new genus, Zapotecanillus gen. n., is established for Z. oaxacanus (type species) sp. n., Z. nanus sp. n., Z. iviei sp. n., Z. ixtlanus sp. n., Z. montanus sp. n., and Z. kavanaughi sp. n. from the Sierra Madre de Oaxaca, Z. pecki sp. n. from the Sierra Madre del Sur, and Z. longinoi sp. n. from the Sierra Madre de Chiapas. A taxonomic key for all described species of Zapotecanillus and a cladistic analysis, based on morphological data, are provided. Morphological, behavioral and biogeographical aspects of the speciation in the genus obtained from the resulting cladogram are discussed.

The size increase of skin epithelial cells during aging is well-known. Here we demonstrate that treatment of aging cells with cytochalasin B substantially decreases cell size. This decrease was demonstrated on a mouse model and on human skin cells in vitro. Six nude mice were treated by topical application of cytochalasin B on skin of the dorsal left midsection for 140 days (the right side served as control for placebo treatment). An average decrease in cell size of 56±16% resulted. A reduction of cell size was also observed on primary human skin epithelial cells of different in vitro age (passages from 1 to 8). A cell strain obtained from a pool of 6 human subjects was treated with cytochalasin B in vitro for 12 hours. We observed a decrease in cell size that became statistically significant and reached 20-40% for cells of older passage (6-8 passages) whereas no substantial change was observed for younger cells. These results may be important for understanding the aging processes, and for cosmetic treatment of aging skin.

BACKGROUND: Insects are of interest not only as the most numerous and diverse group of animals but also as highly efficient bio-machines varying greatly in size. They are the main human competitors for crop, can transmit various diseases, etc. However, little study of insects with modern nanotechnology tools has been done. METHODOLOGY/PRINCIPAL FINDINGS: Here we applied an atomic force microscopy (AFM) method to study stimulation of ladybird beetles with light. This method allows for measuring of the internal physiological responses of insects by recording surface oscillations in different parts of the insect at sub-nanometer amplitude level and sub-millisecond time. Specifically, we studied the sensitivity of ladybird beetles to light of different wavelengths. We demonstrated previously unknown blindness of ladybird beetles to emerald color (∼500nm) light, while being able to see UV-blue and green light. Furthermore, we showed how one could study the speed of the beetle adaptation to repetitive flashing light and its relaxation back to the initial stage. CONCLUSIONS: The results show the potential of the method in studying insects. We see this research as a part of what might be a new emerging area of "nanophysiology" of insects.