bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability analysis of reservoir computers dynamics via Lyapunov functions
Authors: Shirin Afroza , Klickstein Isaac S. , Sorrentino Francesco
Published: October 2019

A Lyapunov design method is used to analyze the nonlinear stability of a generic reservoir computer for both the cases of continuous-time and discrete-time dynamics. Using this method, for a given nonlinear reservoir computer, a radial region of stability around a fixed point is analytically determined. We see that the training error of the reservoir computer is lower in the region where the analysis predicts global stability but is also affected by the particular choice of the individual dynamics for the reservoir systems. For the case that the dynamics is polynomial, it appears to be important for the polynomial to have nonzero coefficients corresponding to at least one odd power (e.g., linear term) and one even power (e.g., quadratic term).
Magnetotransport evidence for topological phase transition in a Dirac semimetal
Authors: Zheng Wen-Zhuang , Ye Xing-Guo , Lin Ben-Chuan , Li Rong-Rong , Yu Da-Peng , Liao Zhi-Min
Published: October 2019

Dirac semimetals transform into Weyl semimetals by breaking the time reversal symmetry, resulting in interesting physical properties, such as the chiral anomaly induced negative magnetoresistance and the Weyl orbit related quantum transport. Here, we report the disappearance of the Weyl semimetal phase in Dirac semimetal Cd3As2 nanoplates with a (112) surface plane when applying a perpendicular high magnetic field. The Landau fan extracted from the notable quantum oscillations shows the nontrivial Berry phase π for B<9.4 T and its disappearance at around 1/B∼0.1 T−1. Our observations indicate the topological phase transition from nontrivial states to gap-opening states induced by the C4 rotational symmetry breaking under a high magnetic field.
Chebyshev centres, Jung constants, and their applications
Authors: Alimov A. R. , Tsar’kov I. G.
Published: October 2019

The approximation of concrete function classes is the most common subject in the theory of approximations of functions. An important particular case of this is the problem of the Chebyshev centre and radius. As it turns out, this problem is not only a special case of the Kolmogorov width problem, but it is also related in a mysterious way to other important characteristics and results in the theory of functions and other more general branches of analysis and geometry. The aim of the present study is to give a survey of the current state of this problem and to discuss its possible applications.

Bibliography: 169 titles.
Circle problem and the spectrum of the Laplace operator on closed 2-manifolds
Authors: Popov D. A.
Published: October 2019

In this survey the circle problem is treated in the broad sense, as the problem of the asymptotic properties of the quantity

, the remainder term in the circle problem. A survey of recent results in this direction is presented. The main focus is on the behaviour of

on short intervals. Several conjectures on the local behaviour of

which lead to a solution of the circle problem are presented. A strong universality conjecture is stated which links the behaviour of

with the behaviour of the second term in Weyl’s formula for the Laplace operator on a closed Riemannian 2-manifold with integrable geodesic flow.

Bibliography: 43 titles.
A demographic study of the water-rat (Hydromys chrysogaster) on the River Torrens in Adelaide, South Australia
Authors: Leigh C. M. , Breed W. G.
Published: October 2019

The population of water-rats (Hydromys chrysogaster) on the River Torrens in Adelaide was monitored over a three-year period. Initially, the population density was high but it became greatly reduced after the water level was lowered and did not recover again until over a year after the high water level had been restored. Males tended to have a larger home range than did females although they did not appear to exclude other individuals from their territory. Breeding generally took place in spring and summer although a few young appeared to be produced in most months of the year. This high population of water rats may, to some extent, be due to the abundance of the exotic fish species that occur in the River Torrens.
Relation between gamma oscillations and neuronal plasticity in the visual cortex
Authors: Galuske Ralf A. W. , Munk Matthias H. J. , Singer Wolf
Published: October 2019

Significance

Learning is thought to be mediated by activity-dependent modification of neuronal interactions. To avoid maladaptive modifications of synaptic transmission by spurious activity, synaptic plasticity has to be gated. In the case of supervised learning, these gating functions are accomplished by reinforcement through value-assigning systems. Here we show that the dynamic state of local circuits correlates with the occurrence of activity-dependent long-term changes in neuronal response properties. We find that repeated visual stimuli induce long-term changes of orientation preference of neuronal populations in visual cortex if stimuli induce synchronized population responses oscillating at ɣ-frequencies. This suggests that neuronal plasticity is controlled by a hierarchy of gating systems and assigns critical gating functions to resonance properties of local circuits.
Linking global drivers of agricultural trade to on-the-ground impacts on biodiversity
Authors: Green Jonathan M. H. , Croft Simon A. , Durán América P. , Balmford Andrew P. , Burgess Neil D. , Fick Steve , Gardner Toby A. , Godar Javier , Suavet Clément , Virah-Sawmy Malika , Young Lucy E. , West Christopher D.
Published: October 2019

Consumption of globally traded agricultural commodities like soy and palm oil is one of the primary causes of deforestation and biodiversity loss in some of the world’s most species-rich ecosystems. However, the complexity of global supply chains has confounded efforts to reduce impacts. Companies and governments with sustainability commitments struggle to understand their own sourcing patterns, while the activities of more unscrupulous actors are conveniently masked by the opacity of global trade. We combine state-of-the-art material flow, economic trade, and biodiversity impact models to produce an innovative approach for understanding the impacts of trade on biodiversity loss and the roles of remote markets and actors. We do this for the production of soy in the Brazilian Cerrado, home to more than 5% of the world´s species. Distinct sourcing patterns of consumer countries and trading companies result in substantially different impacts on endemic species. Connections between individual buyers and specific hot spots explain the disproportionate impacts of some actors on endemic species and individual threatened species, such as the particular impact of European Union consumers on the recent habitat losses for the iconic giant anteater (Myrmecophaga tridactyla). In making these linkages explicit, our approach enables commodity buyers and investors to target their efforts much more closely to improve the sustainability of their supply chains in their sourcing regions while also transforming our ability to monitor the impact of such commitments over time.
Pre-detection history of extensively drug-resistant tuberculosis in KwaZulu-Natal, South Africa
Authors: Brown Tyler S. , Challagundla Lavanya , Baugh Evan H. , Omar Shaheed Vally , Mustaev Arkady , Auld Sara C. , Shah N. Sarita , Kreiswirth Barry N. , Brust James C. M. , Nelson Kristin N. , Narechania Apurva , Kurepina Natalia , Mlisana Koleka , Bonneau Richard , Eldholm Vegard , Ismail Nazir , Kolokotronis Sergios-Orestis , Robinson D. Ashley , Gandhi Neel R. , Mathema Barun
Published: October 2019

Antimicrobial-resistant (AMR) infections pose a major threat to global public health. Similar to other AMR pathogens, both historical and ongoing drug-resistant tuberculosis (TB) epidemics are characterized by transmission of a limited number of predominant
Mycobacterium tuberculosis
(
Mtb
) strains. Understanding how these predominant strains achieve sustained transmission, particularly during the critical period before they are detected via clinical or public health surveillance, can inform strategies for prevention and containment. In this study, we employ whole-genome sequence (WGS) data from TB clinical isolates collected in KwaZulu-Natal, South Africa to examine the pre-detection history of a successful strain of extensively drug-resistant (XDR) TB known as LAM4/KZN, first identified in a widely reported cluster of cases in 2005. We identify marked expansion of this strain concurrent with the onset of the generalized HIV epidemic 12 y prior to 2005, localize its geographic origin to a location in northeastern KwaZulu-Natal ∼400 km away from the site of the 2005 outbreak, and use protein structural modeling to propose a mechanism for how strain-specific
rpoB
mutations offset fitness costs associated with rifampin resistance in LAM4/KZN. Our findings highlight the importance of HIV coinfection, high preexisting rates of drug-resistant TB, human migration, and pathoadaptive evolution in the emergence and dispersal of this critical public health threat. We propose that integrating whole-genome sequencing into routine public health surveillance can enable the early detection and local containment of AMR pathogens before they achieve widespread dispersal.
Global imprint of mycorrhizal fungi on whole-plant nutrient economics
Authors: Averill Colin , Bhatnagar Jennifer M. , Dietze Michael C. , Pearse William D. , Kivlin Stephanie N.
Published: October 2019

Mycorrhizal fungi are critical members of the plant microbiome, forming a symbiosis with the roots of most plants on Earth. Most plant species partner with either arbuscular or ectomycorrhizal fungi, and these symbioses are thought to represent plant adaptations to fast and slow soil nutrient cycling rates. This generates a second hypothesis, that arbuscular and ectomycorrhizal plant species traits complement and reinforce these fungal strategies, resulting in nutrient acquisitive vs. conservative plant trait profiles. Here we analyzed 17,764 species level trait observations from 2,940 woody plant species to show that mycorrhizal plants differ systematically in nitrogen and phosphorus economic traits. Differences were clearest in temperate latitudes, where ectomycorrhizal plant species are more nitrogen use- and phosphorus use-conservative than arbuscular mycorrhizal species. This difference is reflected in both aboveground and belowground plant traits and is robust to controlling for evolutionary history, nitrogen fixation ability, deciduousness, latitude, and species climate niche. Furthermore, mycorrhizal effects are large and frequently similar to or greater in magnitude than the influence of plant nitrogen fixation ability or deciduous vs. evergreen leaf habit. Ectomycorrhizal plants are also more nitrogen conservative than arbuscular plants in boreal and tropical ecosystems, although differences in phosphorus use are less apparent outside temperate latitudes. Our findings bolster current theories of ecosystems rooted in mycorrhizal ecology and support the hypothesis that plant mycorrhizal association is linked to the evolution of plant nutrient economic strategies.
A global-level assessment of the effectiveness of protected areas at resisting anthropogenic pressures
Authors: Geldmann Jonas , Manica Andrea , Burgess Neil D. , Coad Lauren , Balmford Andrew
Published: October 2019

One-sixth of the global terrestrial surface now falls within protected areas (PAs), making it essential to understand how far they mitigate the increasing pressures on nature which characterize the Anthropocene. In by far the largest analysis of this question to date and not restricted to forested PAs, we compiled data from 12,315 PAs across 152 countries to investigate their ability to reduce human pressure and how this varies with socioeconomic and management circumstances. While many PAs show positive outcomes, strikingly we find that compared with matched unprotected areas, PAs have on average not reduced a compound index of pressure change over the past 15 y. Moreover, in tropical regions average pressure change from cropland conversion has increased inside PAs even more than in matched unprotected areas. However, our results also confirm previous studies restricted to forest PAs, where pressures are increasing, but less than in counterfactual areas. Our results also show that countries with high national-level development scores have experienced lower rates of pressure increase over the past 15 y within their PAs compared with a matched outside area. Our results caution against the rapid establishment of new PAs without simultaneously addressing the conditions needed to enable their success.
Mode of action of quinoline antimalarial drugs in red blood cells infected by
Plasmodium falciparum
revealed in vivo
Authors: Kapishnikov Sergey , Staalsø Trine , Yang Yang , Lee Jiwoong , Pérez-Berná Ana J. , Pereiro Eva , Yang Yang , Werner Stephan , Guttmann Peter , Leiserowitz Leslie , Als-Nielsen Jens
Published: October 2019

Significance

The most widely used antimalarial drugs belong to the quinoline family. The question of their mode of action has been open for centuries. It has been recently narrowed down to whether these drugs interfere with the process of crystallization of heme in the malaria parasite. To date, all studies of the drug action on heme crystals have been done either on model systems or on dried parasites, which yielded limited data and ambiguity. This study was done in actual parasites in their near-native environment, revealing the mode of action of these drugs in vivo. The approach adopted in this study can be extended to other families of antimalarial drugs, such as artemisinins, provided appropriate derivatives can be synthesized.
Scaffold subunits support associated subunit assembly in the
Chlamydomonas
ciliary nexin–dynein regulatory complex
Authors: Gui Long , Song Kangkang , Tritschler Douglas , Bower Raqual , Yan Si , Dai Aguang , Augspurger Katherine , Sakizadeh Jason , Grzemska Magdalena , Ni Thomas , Porter Mary E. , Nicastro Daniela
Published: October 2019

The nexin–dynein regulatory complex (N-DRC) in motile cilia and flagella functions as a linker between neighboring doublet microtubules, acts to stabilize the axonemal core structure, and serves as a central hub for the regulation of ciliary motility. Although the N-DRC has been studied extensively using genetic, biochemical, and structural approaches, the precise arrangement of the 11 (or more) N-DRC subunits remains unknown. Here, using cryo-electron tomography, we have compared the structure of
Chlamydomonas
wild-type flagella to that of strains with specific DRC subunit deletions or rescued strains with tagged DRC subunits. Our results show that DRC7 is a central linker subunit that helps connect the N-DRC to the outer dynein arms. DRC11 is required for the assembly of DRC8, and DRC8/11 form a subcomplex in the proximal lobe of the linker domain that is required to form stable contacts to the neighboring B-tubule. Gold labeling of tagged subunits determines the precise locations of the previously ambiguous N terminus of DRC4 and C terminus of DRC5. DRC4 is now shown to contribute to the core scaffold of the N-DRC. Our results reveal the overall architecture of N-DRC, with the 3 subunits DRC1/2/4 forming a core complex that serves as the scaffold for the assembly of the “functional subunits,” namely DRC3/5–8/11. These findings shed light on N-DRC assembly and its role in regulating flagellar beating.
Tuberculosis diagnosis and treatment under uncertainty
Authors: Cassidy Rachel , Manski Charles F.
Published: October 2019

Significance

Tuberculosis (TB) remains a serious global health problem. A new, more accurate test for diagnosis was endorsed by the World Health Organization in 2010. However, trials showed that using the test did not yield reductions in TB-related deaths. To help understand why, we model how a clinician might decide whether to order tests for TB and whether to treat a patient for TB, with or without test results. We highlight the role of uncertainty about the prevalence of TB and the accuracy of different tests, for patients with different characteristics. We show that, given such uncertainty, a reasonable policy may be to diversify testing and treatment, randomly assigning patients with certain characteristics to different combinations of testing and treatment.
Natural human genetic variation determines basal and inducible expression of
PM20D1
, an obesity-associated gene
Authors: Benson Kiara K. , Hu Wenxiang , Weller Angela H. , Bennett Alexis H. , Chen Eric R. , Khetarpal Sumeet A. , Yoshino Satoshi , Bone William P. , Wang Lin , Rabinowitz Joshua D. , Voight Benjamin F. , Soccio Raymond E.
Published: October 2019

Significance

Generation of heat by brown and beige fat cells is a potential avenue to increased energy expenditure, and thus management of obesity and metabolic syndrome. PM20D1 plays a role in thermogenesis based on mouse studies, but its expression had not been investigated in human adipocytes. Here we show that human
PM20D1
expression is genetically variable at 2 levels. Genotype at certain distant variants correlates with overall
PM20D1
expression levels across all human tissues (an “on/off switch”), while a different variant near the gene determines its regulation specifically in adipocytes by the PPARγ receptor and the antidiabetic drugs that target it (a “rheostat”). Human regulatory genetic variation in
PM20D1
expression is associated with obesity and may ultimately inform individualized medicine approaches.
The radically isolating languages of Flores
Authors: McWhorter John M.
Published: October 2019

The languages of central Flores are all but devoid of affixation, despite that this is hardly typical of the Austronesian languages of their family, including closely related languages elsewhere on the island and nearby ones. A traditional approach to these central Flores languages’ typology is to ascribe their analyticity to grammar-internal drift, under which the disappearance of this affixal battery was due merely to fortuitous matters of stress, analogy, reanalysis, etc. Here I argue that a great deal of evidence suggests that these languages actually underwent heavy second-language acquisition by adults at some point in the relatively recent past, most likely by male invaders from a different island. The evidence includes phenomena familiar from recent developments in creolization theory, as well as a cross-linguistic approach to analyticity and its causes.
Negation in Kulina
Authors: Krasnoukhova Olga , van der Auwera Johan
Published: October 2019

This study reconstructs the development of a negative existential and a negative pro-sentence in the Arawan language Kulina (Brazil-Peru). We demonstrate that the two elements forming the negative existential constructionnowe (hi)ra-are involved in a double polarity swap: (i) an originally neutral lexical item (the dynamic verbnowe‘show’) has become negative through contamination, and (ii) an originally negative element(hi)ra-, which was responsible for the contamination, is bleaching into a semantically neutral auxiliary. This lexemenowe, with the auxiliary used only optionally, also functions as a negative pro-sentence now. Thus, synchronically we have a negative pro-sentence that has its origin in a semantically-neutral lexical item. Neither the source of the negative pro-sentence nor this diachronic path has surfaced in the literature on negation so far and thus they are instructive from diachronic and typological perspectives. The hypothesis enriches the literature on both the Jespersen Cycle and the Negative Existential Cycle.
‘Eastern Europe’ in the English-language press in the twentieth century
Authors: Twardzisz Piotr
Published: October 2019

The general opinion among scholars is that Eastern Europe is primarily a Cold-War term. Although the connection between Eastern Europe and the Cold War cannot be denied, it must be kept in mind that the term was well known and used much earlier. This article provides a synthetic review and discussion of how the phrase (name, term, concept) Eastern Europe was used in western English-language press in a better part of the twentieth century, from around 1900 to 1988. Drawing on the results of a search of a journalistic database, this study examines how the term Eastern Europe combines with other lexical units in press texts in this time period. The architecture of its use is revealed through a detailed analysis of collocations which the key term prefers in journalistic texts. In its numerous uses, the term triggers the sense of otherness in its different incarnations throughout the twentieth century.
Dialogue considered as a social ensemble of voices
Authors: Létourneau Alain
Published: October 2019

The aim of the paper is to use a Bakhtinian theoretical frame to analyze a dialogue episode, which is considered
as a social ensemble of voices. The article starts by putting in place the disciplinary angle taken here, the action domain into
which the piece is taken, which is a specific project in adaptation to climate change, a perspective that also needs to be
explained. Two adjacent theoretical frames, the deliberative hybrid forum and the notion of a common pool resource, are also
briefly presented. We finish by presenting and analyzing a dialogue that occurred on the phone between two persons involved in the
project discussed, showing how it expresses a plurality of voices that is somehow unified by a shared practical perspective.
MicroRNA-519d-3p inhibits cell proliferation and cell cycle G1/S transition in glioma by targeting CCND1
Authors: Ma Lishan , Li Jin
Published: October 2019

Glioma is the most common highly malignant primary brain tumor. MicroRNA-519d-3p exerts important effects in several tumors, but its functional role in glioma remained poorly understood. In this study, we found miR-519d-3p expression was significantly decreased in glioma tissues and cell lines. Moreover, the in vitro experiments showed that overexpression of miR-519d-3p suppressed cell proliferation and induced cell cycle G0/G1 phase arrest using MTT and flow cytometry assays in glioma cell lines, U87 and U251. Mechanistically, Cyclin D1 (CCND1) was predicted and confirmed as the direct target genes of miR-519d-3p using luciferase report assay. In addition, knockdown of CCND1 imitated the suppressive effects of miR-519d-3p on cell proliferation and cell cycle progression. Furthermore, restoration of CCND1 reversed the effects of miR-519d-3p overexpression in glioma cells. Taken together, these data demonstrate that suppression of CCND1 by miR-519d-3p might be a therapeutic target for glioma.

Abbreviations miR-519d-3p: microRNA-519d-3p; CCND1: Cyclin D1; ATCC: American Type Culture Collection; MTT: 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide; PI: propidium iodide; WT: wild type; MUT: mutant type; SD: standard deviation
Ultrasonic method for measuring of the electrolyte condition in the discharge burning process with a liquid electrode
Authors: Al-Umari I H A , Kashapov N F , Saitkulov V G , Fazlyyyakhmatov M
Published: October 2019

The article is devoted to the development of the ultrasonic method for measuring of the electrolyte condition in the discharge burning process. The phenomena occurring in the electrolyte in the discharge process are considered. A mathematical model for describing gas bubbles in the electrolyte is proposed. A block diagram of the measuring apparatus is proposed.
Structure of the mathematical model of applying wear-resistant coatings by a high-frequency induction plasma of low pressure
Authors: Sharifullin S N , Akhmadullin A R
Published: October 2019

Annotation

In this scientific work, we proposed a scheme for the transformation of a physical model of applying the HFI plasma coating to a mathematical one in a mathematical way by stepwise solving the problems of the structural model stages. The equations of conservation of energy of the electron gas, Maxwell, continuity and momentum will be used. It is planned to develop a mathematical model for sputtering dielectric and metallic materials. In this case, boundary conditions will be introduced for the discharge power, flow rate and gas types, pressure and design parameters of the plasma torch.
Eulerian-lagrangian model of interphase heat and mass transfer in three-phase low temperature plasma jet
Authors: Brenerman M H , Shaekhov M F
Published: October 2019

Mathematical description of interphase heat and mass transfer in aerosoles and gas suspensions is often based on continious mixture model (Eulerian approach), which in some cases is not physically justified. Such situation takes place for ultra dispersed powder sublimation in plasma jets. For numerical modeling here is suggested Eulerian-Lagrangian model (particle – plasma interaction). Such model allows to calculate maximal productivity of plasma jet sublimation process.Results of calculations are in good concurrence with experimental observation.
The Influence of DC discharge afterglow treatment on poly(ethylene terephthalate) surface properties
Authors: Vasilkin D P , Shikova T G , Smirnov S A , Nikitin D I
Published: October 2019

In this work, we investigated the effects of gas flow rate, processing time and distance from plasma region on the modification of poly(ethylene terephthalate) (PET) films under conditions of afterglows of atmospheric pressure discharges in air and argon. Both original and plasma-modified surfaces were studied by FTIR, AFM, XPS and contact angle measurements. It was found that the remote treatment 1) results in increasing PET surface hydrophilicity, but in decreasing contact angles (by ∼ 3 times compared with the original sample); 2) leads to the destruction of ester groups as well as to the formation of new C-O groups; and 3) causes an increase in average surface roughness (from 1.4 nm for untreated PET to 2.2 and 4.4 nm for PET modified by air and argon afterglows, respectively). The set of experimental techniques together with plasma modeling provided the information on plasma emission properties, gas temperature, reduced electric field strength, discharge geometry and densities of plasma active species. Based on these data, the modification mechanism involving UV photons and O atoms was proposed.
Study of the composition of a hydrophobic coating obtained by a plasma chemical deposition from the gas phase on the surface of textile material
Authors: Vishnevskaya O V , Voznesensky E F , Ibragimov R G , Vishnevsky V V , Ostrovskaya A V , Kharapudko Yu V , Mustafin L R , Yu Mahotkina L
Published: October 2019

In this work, a hydrophobic non-continuous granular coating with a thickness of no more than 1-3 microns, obtained by modifying textile materials with nonequilibrium low temperature plasma (NLTP) in argon-acetylene medium (70:30), was investigated. As a result, the obtained coating is a mixture of hydrocarbons, mainly paraffins, as well as unsaturated hydrocarbons formed during the polymerization and decomposition of acetylene in the presence of copper, such as alkenes, polyacetylene isomers and others, which contribute to an increase in waterproofing properties.
Study of laser cutting of low-alloy steel with using various gases
Authors: Gabdrakhmanov Az T , Israphilov I H , Shafigullin L N , Gabdrakhmanova T F
Published: October 2019

Based on the laser cutting of steel 09G2S, specific features of the power tool and its use are shown. The basic requirements for the quality of the cut surface and a wide range of material properties arising from the characteristics of the energy tool are formulated. The formation of a heat-affected zone, its structure and properties, the formation of macro- and microgeometry of the cut depending on the used working gas are described. The influence of laser cutting parameters on the provision of the required quality and properties of steel is considered.
Steam-gaseous discharges with jet fluid electrodes at the decreased pressure
Authors: Gaisin Al F , Son E E , Kashapov N F , Petryakov S Y , Gaisina A I
Published: October 2019

In this work the experimental research of low temperature plasma of frequency capacitive discharge and constant currents discharge with jet fluid electrodes in pressure range of p = 105 − 103
Pa are presented. The area where the field gradient exceeds the threshold value necessary for temporary use of the steam-gaseous discharges is presented. The plasma radiation spectrum is presented. Estimates on composition of plasma, an electron concentration and temperature of a heavy component are presented.
An analytical model of glow discharge positive column in axially symmetric channel with variable cross section
Authors: Galeev I G , Ya Asadullin T , Shakirov A S
Published: October 2019

A model of glow discharge positive column in gas flow is considered in this paper. It is supposed the discharge is between the permeable mesh electrodes installed in the initial and end sections of axially symmetric channel. In general case the channel width changing along the stream is accounted. The positive column in gas flow is described by integro-differential system of equations with an approximation of constant gas flow density. The border conditions for gas ionization degree and temperature in the initial section of channel are given by any functions. An analytical solution of that system was obtained. The special cases of the boundary conditions are analyzed.
Synthesis of carbon nanotubes in arc plasma from liquid hydrocarbons
Authors: Timerkaev B A , Ganieva G R
Published: October 2019

In the presented research the experimental setup is proposed and the new method for the multilayer carbon nanotubes synthesis from liquid hydrocarbons is described. The systematic studies of the drowned electric arc interaction in the hydrocarbon feedstock with hydrocarbon molecules were carried out to obtain atomic carbon. The resultant product in the carbon black form was analysed through the electron microscope. It is shown that much carbonaceous deposits on the cathode are contained in carbon nanotubes.
Pulsating combustion of the propane-butane mixture with air and gas ionization in a tube
Authors: Malahov A O , Larionov V M , Saifullin E R , Sadikov K G , Gaianova T E
Published: October 2019

While an ionization during laminar or turbulent combustion has been studied quite well, the ionization processes in pulsating combustion of gases not so well known. In this paper, pulsating combustion of propane-butane mixture with air and gas ionization in the vortex chamber is considered.
The phenomenon of bicyclones a high-frequency induction discharge and the related questions of flows in channels with the presence of zones of heating, bounded along the longitudinal coordinate
Authors: Gerasimov Alexander , Kirpichnikov Alexander , Sabirova Farida
Published: October 2019

The phenomenon of a bicyclones in a high-frequency induction discharge is explained. It is shown that this phenomenon should be characteristic of a wider range of objects having an internal heat source, limited by the longitudinal coordinate. In the present work, this phenomenon is considered as peculiar to fairly wide class of flows in cylindrical channels if there are one or several heating zones (internal or external) inside these channels, limited by the longitudinal coordinate.
Composite materials for next generation plasma energy systems
Authors: Smerdov R S , Mustafaev A S , Spivak Yu M , Grabovskiy A Y , Moshnikov V A
Published: October 2019

The investigation of graphene and porous silicon (PS) composite materials for low work function PETE (photon-enhanced thermionic emission for solar concentrator systems) energy systems synthesis is performed in this article. These two types of materials are suggested for further development and study due to noteworthy physical effects taking place in the aforementioned structures. The nature of low-work function phenomenon is interpreted as related to the influence of functionalization and synthesis parameters on the surface structure of composite materials. The Raman spectroscopy technique is used to characterize porous silicon based nanostructured composite layers (PS/Ag). The interpretation of PS/Ag Raman spectra is suggested. The significant decrease in the effective electron work function to a value of 1 eV is registered in a perforated graphene-covered nickel anode intercalated with Cs atoms. SEM X-ray microanalysis of the anode surface is performed, the interpretation of the anode work function lowering effect is proposed.
Synthesis of carbon nanostructures in electric discharge
Authors: Timerkaev B A , Shakirov B R , Galieva A L , Vafina A G , Kaleeva A A , Yalaltdinova G D
Published: October 2019

A synthesis method of carbon nanomaterials in an argon arc is described in this paper. The two separate cases have been considered. In the first case it is carried out by evaporation of a graphite anode followed by deposition of carbon vapor on a tungsten cathode. In the second case the anode material was specially synthesized in the electric arc recessed into liquid hydrocarbon raw material. The fuel oil was used as a hydrocarbon raw material. During that decomposition of this material took place and as a result carbon deposits were formed on the electrodes. Then these carbon deposits were used as the arc discharge anode at the next stage of the process. In both cases the carbon synthesis of nanotubes was carried out on the tungsten cathode surface. There was the intensive growth of carbon nanotubes during the experiments.
Research of the effect of radio-frequency capacitive plasma treatment in the medium of hydrocarbon gas on properties of the surface of glass fibers
Authors: Karimullin I I , Karnoukhov A E , Skidchenko E A , Yu Makhotkina L , Voznesensky E F , Trofimov A V
Published: October 2019

The paper presents the results of a study of the effect of radio-frequency (RF) capacitive low-pressure discharge on the properties of glass fibers. It is shown that RF capacitive plasma modification in the medium of hydrocarbon gas imparts hydrophobic properties of the material surface.
Pulsating burning of petroleum coke in the Rijke tube
Authors: Larionov V M , Iovleva O V , Saifullin E R , Muhametov I R , Larionova I V
Published: October 2019

In this paper, the combustion of petroleum coke is investigated. It is established that fluctuations of gas in the Rijke tube excited when petroleum coke burns with propane-air mixture. It is shown that over time the mixture supply can be significantly reduced due to the intensification of coke combustion by oscillations.
Application of the rescaled range analysis for vibro-acoustic imbalance control of rotary equipment
Authors: Malahov A O , Zagretdinov A R , Ziganshin Sh G , Vankov Yu V
Published: October 2019

The article discusses the possibility of using R/S analysis for vibro-acoustic unbalance control of rotary equipment. An algorithm for R/S analysis is presented. An application package and an information-measuring complex have been developed. Experimental studies on an axial ventilator are conducted. It has been established that in the absence of ventilator imbalance, the vibro-acoustic signal is close to random. With the advent of imbalance, the Hurst exponent changes.
Radio Frequency Plasma Modification and Physicochemical Properties of Electrochemically Produced Co Nanoparticles
Authors: Mironov M. M. , Dresvyannikov A. F. , Kolpakov M. E. , Sharifullin F. S. , Sysoev V. A. , Krasina I. V.
Published: October 2019

With the help of the TEM and XRD methods, Co sediments produced by an electrochemical method and then modified with RF discharge have been studied. Aggregates with dimensions up to 800 nm are found to be prevailing in the sediment before RF modifications, and branched chains consisting of particles 60—80 nm in size are found after modification. The main phase in the sediments is Co in the hexagonal and cubic modifications.
Nanobarrier coating for elements of gas chromatograph
Authors: Muradi M , Luchkin A G , Morozov G S , Fayzrakhmanov I A
Published: October 2019

In this paper, we consider a method of protecting the surface of the components of a gas analytical system from corrosion and adsorption of sulfur-containing compounds. To solve this problem in the oil and gas industry, in particular in industrial analytical equipment, silicon coatings are used that are inert with respect to the measured substances. Based on the analysis, the regularity of the formation of films of silicon films obtained by plasma-chemical deposition (PECVD) on stainless steel products was investigated.
Information-measuring system for monitoring the location of underground gas pipelines on the basis of improved acoustic resonance method
Authors: Nazarychev S A , Gaponenko S O , Kondratiev A E , Shakurova R Z
Published: October 2019

Instrument established on the basis new method of detection hidden channels and gas pipelines, made of both metal and non-metallic materials. For the operation of the information-measuring complex was developed and created soft-ware and hardware. Laboratory and in-situ studies have been conducted to confirm the performance of the proposed technical solution.
The effect of the external acoustic waves on the plasma torch jet
Authors: Saifutdinov A I , Fadeev S A
Published: October 2019

Numerical experiments on the effect of the external acoustic waves on the plasma torch jet have been performed. The formation of a turbulent plasma torch jet upon application of an external acoustic waves is demonstrated.
Increasing the capillary of fiberglass under the application of a relief coating in the low-pressure radio-frequency induction discharge
Authors: Skidchenko E A , Voznesensky E F , Sysoev V A , Lutfullina G G , Karnouhov A E , Karimullin I I , Sitarsky S K
Published: October 2019

the article presents the results of experimental studies of the effect of low-pressure radio-frequency induction discharge on the glassfiber capillarity indexes after the formation of a functional microrelief of SiO2 particles on the surface of fiberglass.
Mathematical modelling of turbulent gas flow with particles based on eulerian approach
Authors: Gubaidullin D A , Snigerev B A
Published: October 2019

In Eulerian variables the mathematical model for calculating the hydrodynamic and thermal parameters of the dispersed mixture are presented. The mathematical model is based on the use of Eulerian description of mass conservation, the amount of motion for liquid and solid, recorded in the framework of the theory of interacting continuums. The turbulent characteristics of the gas are calculated using a modified transport model of the Reynolds stress tensor components, taking into account the presence of solid phase in the medium. The model allows to investigate the effect of non-isotropy of turbulent fluctuations of particle velocities, the ratio of the thermal properties of the particle material and the carrier gas on the intensity of momentum, heat and mass transfer in the dispersed phase.
Electric arc method for synthesis of silicon nanotubes
Authors: Timerkaev B A , Shakirov B R , Petrova O A , Feltsinger V S
Published: October 2019

This paper proposes a method for creating silicon nanotubes in electric arc plasma, by evaporating the anode material and collection it on the cathode. During the experiments, various types of power sources were tested. Silicon nanotubes of complex configuration in the form of a straight stem with cylindrical branch and single-wall curved nanotubes were obtained. The obtained nanotubes will be able to find further application in light-emittingdiodes, lithium-ion batteries, and photovoltaics.
Electric arc synthesis of germanium nanotubes
Authors: Timerkaev B A , Skvortsov S V , Feltsinger V S , Shakirov B R
Published: October 2019

This paper describes the experimental setup and outlines the original methodology for conducting an experiment on growing germanium nanostructures. The obtained samples were examined with an electron microscope. It is shown that this technique allows one to grow both germanium nanotubes and germanium.
Development of plasma reactor design for synthesis of copper nanoparticles using multi-scale simulation
Authors: Fairushin I.I. , Saifutdinov A.I. , Sofronitskiy A.O. , Timerkaev B.A. , Dautov G.Yu.
Published: October 2019

On the basis of the hybrid hydrodynamic model for the gas discharge, numerical experiments were performed. The main parameters of the electric discharge of a direct current with copper cathode and anode were obtained. The obtained data were used as the main conditions for molecular-dynamics simulations of the copper vapor nucleation process in the argon. The results of the simulation formed the basis for the development of an experimental setup for the plasma synthesis of copper nanoparticles.
Mathematical modeling of deposition process of charged polymeric particles on moving surface
Authors: Fedyaev V L , Khaliulin V I
Published: October 2019

The deposition of charged polymeric particles in the gravitational and electrostatic fields on a moving surface is considered. A mathematical model is proposed, as a result of a number of simplifications analytical solutions are found. The rational design parameters of the installation and the technological modes of its operation are determined.
The influence of plasma power with a liquid electrode on the microhardness of gray cast iron
Authors: Khafizov A A , Shakirov Yu I , Valiev R I , Valiev R A
Published: October 2019

The effect of a plasma jet in an installation with an electrolytic cathode on the structure and properties of gray iron has been investigated. The dependences of the sizes of the zone of plasma treatment influence, the average diameter of dendrites and microhardness on the plasma power in the range of 2 to 6 kW have been determined. It has been established that as the plasma jet power increases, the volume of the reflow zone and the size of the grains of its structure increase, while the microhardness of the treated cast iron decreases.
Study of aerosol behavior under resonant vibrations in the vicinity of an open end of a pipe
Authors: Gubaidullin D A , Zaripov R G , Tkachenko L A , Shaidullin L R
Published: October 2019

Annotation

The aerosol movement at an open end of a pipe at the resonant frequency was experimentally studied. The aerosol flow in an external wave field was visualized. The numerical value of the Rayleigh correction for an open end of an experimental plant was obtained. A good agreement between the numerical and experimental values was demonstrated.
Modeling of the influence of non-stationary waves in three-component medium in the formation of a plasma jet
Authors: Sharifullin S N , Yu Zhachkin S , Trifonov G I
Published: October 2019

This article discusses the mathematical description of the physical processes of transformation of composite substances of a plasma jet. A mathematical model describing the propagation of elastic waves in a three-component medium was developed for the prediction and planning of the use of plasma deposition technology, in particular in the study of the kinematic characteristics of the plasma flow. Also in the course of mathematical modeling the table of coefficients of compressibility of liquid (plasma jet) and gas and velocities of longitudinal and transverse elastic waves is obtained. Graphs of the velocity of propagation of longitudinal and transverse waves in the plasma coating material on its physical and mechanical characteristics-compressibility coefficients are plotted.
Properties of coatings formed by plasma electrolytic oxidation on plastically deformed aluminum alloy AO3-7
Authors: Kolomeichenko A V , Sharifullin S N , Logachev V N , Kuznetsov Yu A , Kravchenko I N , Baranov Yu N
Published: October 2019

The article presents the research results of the influence of electrolyte composition and plasma electrolyte oxidation (PEO) modes on microhardness and wear resistance of coating formed on a bush of the gear type pump HШ-У, which is reconditioned by plastic deformation.
Investigation of parameters of low-temperature gas discharge plasma with liquid electrodes upon receipt of metal powder
Authors: Kashapov R N , Kashapov L N , Kashapov N F
Published: October 2019

Selective laser melting technologies are widely used in various industries and medicine. A gradual increase in the volume of manufactured products requires the creation of new cheap methods for producing metal powders. One of the new methods for producing powders is the plasma-electrolyte method. A feature of this method is the use of gas with liquid electrodes, which allows you to get a metal powder and quickly cool it in a liquid. The question of the influence of discharge parameters on the process of metal atomization remains open. The paper studies gas discharges with liquid electrodes under the conditions of atomization of a metal anode. A gas discharge between a liquid electrolyte and a metal electrode was studied experimentally in the voltage range 300 - 1000 V. Solutions of sodium chloride in distilled water were used as the electrolyte. The conditions are established under which a stable discharge column is formed and metal powder is sprayed. The regularities of the change in the CVC of the discharge depending on the interelectrode distance are determined. A splitting of the spectral lines of the yellow sodium doublet was found in the emission spectrum of a gas discharge.
Investigation of CoCr micropowder obtaining process in gas discharge with liquid electrodes
Authors: Kashapov R N , Kashapov L N , Kashapov N F
Published: October 2019

Plasma technologies have a wide range of applications: from agriculture and the food industry to energy industry. Such widespread use is due to the properties of plasma and a wide variety of methods for its preparation. Also, in metallurgy, plasma is used as a source of thermal energy, capable of producing metal melting in a short time. The paper studies the process of obtaining a metal powder from a CoCr alloy in a gas discharge with liquid electrodes. The regularities describing the relationship between discharge parameters and properties of the powders obtained. The resulting powders can be used in Selective Laser Melting technology.
Research on International Power Network Construction in Central-Asia
Authors: Li Juan , Sun Yang , Zhou Hong-lian , Yang Nan , Liu Ling-shuang , Zhou Er-biao , Li Zhong-zheng , Yuan Tie-jiang
Published: October 2019

As part of the Belt and Road Initiative, China promises to provide its abandoned renewable energies in Xinjiang for solving the power shortage problem in Central-Asia countries. This brings a great chance for energy investment and cooperation in power grid construction between China and Central-Asia countries. This paper analyses the power structure and energy institutions in 6 Central-Asia countries and predicts its energy potential and power requirement based on its GDP growth rate. A power grid connection plan is further proposed based on the predictions. This power grid construction would benefit all the countries involved and boost area economic growth for years.
A Device for Online Monitoring of the Measurement Accuracy of Digital Electric Energy Meter
Authors: Li Yuchun , Huang Dongdong , Shi Xudong , Zhan Fajun , Liu Xiaojian , Ge Leijiao
Published: October 2019

The application of smart substation technology has brought many opportunities to the power industry, but also caused many new problems and challenges. At present, with the large-scale promotion of intelligent substation based on IEC61850, there are many engineering problems which will not appear in IEC61850 protocol and are closely related to practical application. A device for online detection of electrical error is designed in the paper for the measurement deviation problem of “IEC61850-9-2 input digital power meter” in the new generation of intelligent substation. The characteristic of the device is that once the meter measurement error is detected within the set time interval, it will record the voltage and current waveform data within the interval in real time for error analysis and problem finding.