bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of the dynamics of expansion of the near-surface light erosion plasma formed during the evaporation of a material by broadband high-brightness radiation
Authors: Pavlov A V , Protasov Yu Yu , Telekh V D , Shchepanuk T S
Published: November 2019

The dynamics of the vapor-plasma flows formed at impact of erosion type magnetoplasma compressor (MPC) discharge radiation on Ti, Al and PTFE targets with use of methods of a holographic interferometry and schlieren photos (Toepler’s scheme in the light field mode) is investigated. In the schlieren and interferogram photos, zones characteristic of the studied process of radiation interaction with matter are well visible: the gas-dynamic evaporation mode is realized (plasma piston mode), there is a shock wave in the gas, the contact boundary between the shock-compressed gas and the vapor plasma. The interferograms analysis indicates that the regime of developed evaporation is preceded by a regime of diffusion evaporation. On the interferograms above the targets at different distances from the radiation source (from the MPC), we observe 3 types of gas-dynamic perturbations: an acoustic wave, a simple wave (Riemann wave), and a shock wave. Qualitative and quantitative description of processes in these zones is discussed in the report. The effect of the radiation spectral composition (we use the method of gas spectral selection), the targets materials, and the degree of surface treatment on the evaporation is shown experimentally.
Computer simulation of high current vacuum arc with developed anode spot
Authors: Shmelev D L , Uimanov I V
Published: November 2019

A self-consistent simulation of anode heating by 4.5 kA vacuum arc during the half-wave of 50 Hz current with 1 m/s contact opening was carried out. The calculations were done in the framework of hybrid high current vacuum arc model, which treats ions and atoms as macroparticles with the help of particle-in-cell methods, but electron subsystem is treated as massless fluid with quasineutrality assumed. The occurrence of an anode plasma plume (similar to that found in experiments) was obtained as a result of modeling. It is shown that the energy flux of line radiation from the interelectrode plasma to the anode is a critical reason of the appearance and maintenance of the anode plume.
On possible reasons of positive near-anode voltage drop in high-current vacuum arc
Authors: Shmelev D L , Barengolts S A , Tsventoukh M M , Uimanov I V , Wang L
Published: November 2019

In this paper we consider some reasons for the occurrence of a positive near-anode potential drop during current constriction in high-current vacuum arc. It is shown that if the radius of constriction is much larger than the electron mean free path, then a positive voltage drop in the near-anode plasma sheath does not occur, but an additional drop may occur in the near-anode plasma layer due to the anomalous resistance. If the current constriction radius is much less than the electron mean free path, then a positive voltage drop in the sheath arises under the usual condition, and the kinetic instabilities in the near-anode plasma do not develop.
Plasma source based on ring-shaped anode layer thruster for a bipolar electron-optical system
Authors: Bugaev A S , Goncharov A A , Gushenets V I , Oks E M
Published: November 2019

The conceptual design of pulsed plasma source for plasma-optic application and materials modification are investigated. The source is based on plasma thruster’s technology, that were developed by Goncharov’s group in Institute of Physics (Kiev, Ukraine). The plasma device with its two modified closed-drift anode layer thrusters can operate in low-current high-voltage mode and in high-current plasma mode. Most attention in the paper is focused on the latter mode being similar to a glow discharge with a positive column. The study shows that under certain conditions, the discharge with closed electron drift can be accompanied by non-self-sustained hollow-cathode discharges with oscillating electrons which greatly decrease the auxiliary discharge voltage. Presented in the paper the current–voltage characteristics of this type of high-current discharge and the spatial distributions of plasma parameters are measured in the discharge region with double Langmuir probe techniques. The maximum plasma densities on the central cathode axis are (6.5÷6.8)×1012 cm–3.
Computer simulation of ion beam-plasma interaction
Authors: Dudnikova G I , Boronina M A , Genrikh E A , Vshivkov V A
Published: November 2019

In the paper a two-dimensional axisymmetric hybrid numerical model of the interaction of an ion beam with a plasma is presented. The model is based on the kinetic approximation for the ions whereas the electrons are assumed to be a fluid. To solve the Vlasov kinetic equation, the author’s modification of the particle in cells method (PIC) is used. It was shown that the magnetic flux can be expelled from the volume filled by the plasma due to the plasma-beam interaction. The dynamics of the magnetic field cavity formation depending on the characteristics of the ion beam and the background plasma is investigated.
Calculation model of the plasma load matching with the current sources based on explosive magnetic generator
Authors: Shurupov M A , Mashtakov A V , Gusev A N , Zavalova V E , Kozlov A V , Shurupova N P
Published: November 2019

In this paper, we consider the model of engineering calculation for the matching of the explosive-magnetic generators (EMG) and pulsed plasma accelerator (PPA) at amplitudes of currents reaching 2.5 MA. The main features of the model are taking into account the dynamics of change in the inductance of PPA and the using of the concentrated mass approximation for the current shell. The taken assumptions were checked by experimental data on real PPA powered by EMG. It is shown that the built model has sufficient accuracy for preliminary calculations for design and installation of such technique.
A new type of non-thermal atmospheric pressure plasma source
Authors: Tikhonov V N , Ivanov I A , Tikhonov A V
Published: November 2019

The unique applications of Non-Thermal Atmospheric pressure Plasmas (NTAP) are associated with its enormous potential for providing technological capabilities for new products and technologies. In such plasmas, most of the electrical energy is deposited in the electron component of the plasma, while plasma ions and neutral components remain at or near room temperature. This paper presents the NTAP source that combines the characteristics of a dielectric barrier discharge (DBD) by discharge configuration and a non-thermal plasma jet (NTPJ) by plasma jet formation.
Electron beam generation with variable current amplitude during its pulse in a source with a grid plasma cathode
Authors: Vorobyov M S , Koval N N , Moskvin P V , Teresov A D , Doroshkevich S Yu , Yakovlev V V , Shin V I
Published: November 2019

In electron sources with grid plasma cathodes, the boundary of the emission plasma is stabilized by a fine-structured grid, the cell size of which is comparable to the size of the Langmuir layer. The correct choice of the cell size of the emission grid allows to stabilize of the emission plasma boundary, reaching a wide range of the parameters adjustment of the generated electron beam with a weak dependence of these parameters on each other. Since the beam current amplitude is most often controlled by a proportional change of the discharge current in the plasma cathode, which allows to change the emission plasma concentration, this paper is investigated the possibility of generating the electron beam having variable amplitude by predicting the change in the discharge current amplitude during its pulse. The described advantage of plasma cathodes makes it possible to obtain electron beams with both a falling and a rising current amplitude of the beam during its pulse. The obtained regimes of electron beam generation open up new possibilities for using this source for both scientific and technological purposes.
Influence of the hole diameter in the perforated electrode on the parameters of electron beam generated by a forevacuum plasma electron source
Authors: Zenin A A , Bakeev I Yu , Klimov A S
Published: November 2019

We present experimental results on geometry optimization of the emission electrode in a plasma cathode electron source operating in the forevacuum range of pressure. For the 2-mm thick emission electrode, we have determined an optimal diameter of the emission aperture that provides the most efficient electron extraction from a hollow cathode glow discharge plasma in helium. At the working pressure of helium in the vacuum chamber 30 Pa, the beam power during emission from a single aperture can vary from 2 to 6 kW, while the beam diameter does not exceed 0.5 mm.
Effect of low-temperature ion nitriding on microhardness, roughness and residual stresses in the surface layer of Ti-6Al-4V
Authors: Agzamov R D , Tagirov A F , Nikolaev A A , Ramazanov K N
Published: November 2019

The paper presents the results of two experimental series with low-temperature nitriding of VT6 titanium alloy in a non-self-maintained high-current arc discharge and in a glow discharge in different regimes. It is shown that microhardness and depth of a surface layer are significantly impacted by the temperature of treatment. The value of surface roughness of the samples is also affected, with a temperature rise from 450 to 600°C resulting in a surface roughness increase by 2–2.5 times. The temperature of nitriding affects the sign and magnitude of residual stresses in a surface layer.
Optimization of the numerical model of the triggerable LTD spark gap switch
Authors: Alexeenko V M , Kondratiev S S , Sinebryukhov V A , Volkov S N
Published: November 2019

In LTD generators, one of the main parts of the primary discharge circuit is the triggerable spark gap switch. For the cavities with oil insulation, the OrCAD switch model was developed [1–3] by taken into account the effect of the trigger pulse on the triggering time of these switches and its spread. According to the real design, the switch in this model is simulated as a block consisting of six independent spark gaps connected in series. However, because of such detailed description of the switch structure this initial model is quite complex causing significant complications in simulation of the full generator in case it includes numerous switches. To avoid that complexity, in the given paper we investigate the possibility to optimize the initial complex model, and present at the output much less complicated switch model with acceptable simulation error.
Production of Al-O-N nanopowders in a plasma reactor with a limited jet flow
Authors: Astashov A G , Samokhin A V , Alekseev N V , Sinayskiy M A , Pakhilo-Daryal I O , Tsvetkov Yu V
Published: November 2019

Experimental studies on the synthesis of aluminum oxynitride nanopowders in a reactor with a confined plasma jet by the interaction of disperse aluminum with ammonia and oxygen in a flow of nitrogen plasma generated in an electric arc plasma torch are performed. Preliminary calculations of the equilibrium compositions and thermodynamic characteristics of the multicomponent Al–O–N system are carried out.
Modeling of the synthesis of ‘core-shell’ composite particles based on segregated oxidation of titanium and silicon tetrachlorides in flow-type plasmachemical reactor
Authors: Aulchenko S M , Kartaev E V
Published: November 2019

The simulation of single-stage synthesis of composite titania-silica nanoparticles in the working zone of flow-type plasmachemical reactor has been performed based on segregated oxidation of titanium and silicon tetrachlorides, with each precursor being preliminarily mixed with air oxygen by means of bubbling. Within the framework of the developed model of the synthesis, the data regarding core size of composite particles, their shell thickness as well as ratio of particles with and without shell have been extracted.
Plasmachemical processing of germanium-containing mineral and technological raw materials
Authors: Batomunkuev D Y , Vashchenko S P
Published: November 2019

This work is a study of the possibility of plasma-chemical enrichment of fly ash. In experiments with a flow reactor, the recovery rate was more more than 99% in slag and 70–80% in unmelted particles. In experiments closed in germanium with the melting of the mineral part of the ash in a reactor with a flowing melt film, an extraction degree of 95–96% was obtained, and the enrichment degree can be estimated as 30–40.
Method for measuring the micro-discharges temperature in the micro-arc oxidation process
Authors: Golubkov P E , Pecherskaya E A , Artamonov D V , Shepeleva J V
Published: November 2019

An automated method for measuring the micro-discharges temperature in the micro-arc oxidation process, allowing measurements to be carried out in real time, is proposed. The design of the measuring transducer, as well as a structural metrological model, taking into account measurement errors is proposed. The possibility of establishing the dependences of the oxide layer micro-hardness on the influencing factors of the micro-arc oxidation process using the Kolmogorov-Johnson-Mehl-Avrami equation by measuring the micro-discharges temperature is shown.
Formed nano-W - WC coatings on the high-speed steel substrate by the electrodischarge explosion
Authors: Grigoryev E G , Smirnov K L , Strizhakov E L , Neskoromniy S V
Published: November 2019

Electric exploding of a tungsten carbide – cobalt material near-by high-speed steel surface forms on it a hardening coating. The essential structure properties of the formed coatings are determined by specifications of contact exploding electrode and the pulse current amplitude and duration. The investigations of coating structures were done by optical and electronic metallography. They have shown that the contact electric exploding caused the transfer of tungsten carbide and cobalt on the surface of high-speed steel. The breakdown of tungsten carbide – cobalt material took place during electrical exploding. The hardening layers of tungsten carbide and pure nanocrystalline tungsten have been formed upon the surface of high-speed steel as a result of electric exploding. Crystalline grains of tungsten have an almost spherical form and their characteristic size less than 400 nm. Micro hardness of the coating layers and high-speed steel structures was measured.
Influence of ion irradiation on the structure and mechanical properties of extruded V95 alloy profiles after artificial aging
Authors: Gushchina N V , Ovchinnikov V V , Makhin’ko F F , Kaigorodova L I , Mozharovsky S M
Published: November 2019

The effect of 10-keV Ar+ ion irradiation on the mechanical properties and structural and phase state of hot-pressed thin profiles 1.5 mm thick and made of an V95 alloy (Al-Zn-Mg-Cu system) after artificial aging (T = 140°C, 16 h) has been studied. Ion beam treatment of the alloy (j = 300 μA·cm−2, F = 1.9·1015 and 1.1·1016 cm−2) without heating the samples to significant temperatures (T < 35–50°C) has not been established to change the ultimate strength and yield strength; however, it increases the relative elongation by 1–2 %. Transmission electron microscopy has shown that irradiation changes the grain structure and the morphology of particles of the crystallization origin in the entire volume of quenched and artificially aged V95 alloy samples (1.5 mm thick). The irradiation does not affect the size and the volume fraction of fine strengthening η′- and η-phase particles.
Effect of irradiation and subsequent aging on the structure of a B-1461 alloy of the Al–Cu–Li–Zn system after megaplastic deformation
Authors: Gushchina N V , Ovchinnikov V V , Makhin’ko F F , Kaigorodova L I , Rasposienko D Yu
Published: November 2019

The effect of Ar+ ion irradiation and subsequent prolonged aging on the microstructure and phase transformations in a B-1461 alloy (Al–Cu–Li–Zn–Mg–Zr–Sc) subjected to megaplastic deformation (MPD) has been studied by transmission electron microscopy. A mixed structure, consisting of nanocrystalline and nanofragmented regions has been found to form in the alloy upon MPD. Subsequent short-term Ar+ ion irradiation (E = 20 keV, j = 300 μA·cm−2, F = 1.9×1015 cm–2) forms dislocation tangles, increases the nonuniform distribution and the size of structural elements, as well as volume fraction of a T2-phase (Al3CuLi5) nano and submicrocrystals heterogeneously nucleated at boundaries. Structural changes are observed at a distance of ~ 200 μm from the surface, which considerably exceeds the projective ion range (~ 20 nm). The structure of the B-1461 alloy after MPD and subsequent irradiation under the above conditions is unstable.
Features of electron-beam processing of metal-ceramic powders in the forevacuum
Authors: Klimov A S , Zenin A A , Tu Tran Van , Bakeev I Yu
Published: November 2019

We present the results of sintering of a metal-ceramic sample consisting of alumina ceramics and titanium. Sintering has been conducted via the surface scanning by the electron beam generated by a plasma electron source. It has been shown that the bake-out temperature affects the formation of the layer with a uniform distribution of elements. We have determined the sintering regimes that enable fabrication of samples with uniformly distributed elements over volume.
Electron-beam plasma and its applications to polymer treatment in the forevacuum
Authors: Klimov A S , Zenin A A , Tu Tran Van , Bakeev I Yu
Published: November 2019

We present our studies of the parameters of helium beam plasma. The beam plasma was generated by a powerful focused electron beam propagating through helium atmosphere at a pressure of 25 Pa. The beam power varied in the range 80 to 1000 W. We have determined the electron beam parameters that enable one to generate a beam plasma with a density greater than 1016 m−3. Using the plasma ions, we have conducted treatment of polymer materials. It has been shown that the beam plasma treatment in the forevacuum range of pressure enhances the hydrophilic properties of fluoroplastic surfaces.
Nanostructuring of the T31507 steel surface by vanadium borides under the influence electron beams in a vacuum
Authors: Milonov A S , Dasheev D E , Smirnyagina N N
Published: November 2019

The microstructures and microhardness of boride layers formed on die steel of T31507 by electron-beam boron reduction in vacuum are investigated and compared. Formed layers have a heterogeneous structure, combining solid and plastic components, leading to a decrease in brittleness of the boride layer.
Influence of nitrogen pressure and electrical parameters of a glow discharge on the process of ion plasma nitriding of steel
Authors: Oskirko V O , Goncharenko I M , Pavlov A P , Zakharov A N , Semenov V A
Published: November 2019

The influence of the working gas pressure on the electrical parameters of the glow discharge and the structure of diffusion hardened layers in the process of ion-plasma nitriding of steel AISI 5140 was investigated. The experiments were carried out in the pressure range of 70–500 Pa, while the power (18 kW), the temperature of the samples (550 °C) and the processing time (6 hours) remained unchanged. The change in gas pressure was accompanied by a change in discharge voltage in the range from 560 to 1800 V and current density from 3.2 to 1.1 mA·cm−2. It is shown that the change in the pressure of nitrogen leads to a change in the energy and density of the particles flows acting on the workpieces. Metallographic and X-ray analysis showed that the surface layers formed at different pressures differ in length, structure, and phase composition. In particular, the maximum width of the diffusion zone of 460 microns was achieved at an operating pressure of 250 Pa The increase and decrease in pressure leads to a decrease in the length of the diffusion zone and an increase in the compound layer to 26 μm.
Phase composition of powder products obtained in direct current atmosphere arc plasma synthesis at the “molybdenum-carbon” system
Authors: Pak A Ya , Yakich Y Tu , Tarasova O V
Published: November 2019

In this paper you can see the results of experimental studies that are devoted to the production of powder. To obtain these materials, an electric arc method without vacuum was used, based on the effect of spontaneous shielding of the reaction zone by gaseous products of combustion of a direct current arc discharge in the gap between graphite electrodes. A feature of the approach used is its implementation without the use of vacuum equipment. The process of electric arc synthesis is implemented in a cylindrical cavity of a graphite cathode, in which a powder mixture of carbon and molybdenum is present. As a result of experiments, multiphase powder products were obtained, which were collected from various parts of the discharge loop electrode system. Three types of products were obtained: collected from the walls of the cylindrical cavity of a graphite cathode, collected from its bottom, and also collected in the form of a cathode deposit. Differences in the phase composition of the products obtained were revealed, and the morphology of micro-sized particles in the synthesis product was determined.
Cascade volumetric acceleration of electrohydrodynamic flows
Authors: Rebrov I E
Published: November 2019

Method of cascade volumetric acceleration of electrohydrodynamic flows at atmospheric pressure air using high-voltage rectangular pulse generator was developed and investigated. The charged particles generated by dielectric barrier or corona discharge and accelerated by synchronizing the ion cloud movement with electric field change of the accelerating electrodes. To implement synchronous switching, a two-channel high-voltage square wave generator was used. It consists of 4 high-voltage switches combined in pairs in a half-bridge circuit and operates at frequency from 100 Hz to 100 kHz and voltage of up to 10 kV. Due to the controlled turning on and off of the switches, the minimum duration of high-voltage pulses is less than 200 ns. The generator is loaded with a two-phase multistage volumetric acceleration system of ion clouds.
Atmospheric pressure diffuse discharge treatment of aqueous solution of methylenum coeruleum
Authors: Ripenko V S , Erofeev M V , Tarasenko V F
Published: November 2019

High voltage atmospheric cold plasma is a novel, non-thermal technology which has shown potential for degradation of various toxic components in wastewater. In this study, the degradation of methylene blue in aqueous solution as a model dye using a cold diffuse plasma source at atmospheric pressure has been investigated. Ambient air used as feed gas and aqueous solutions with same concentrations of the dye were treated by runaway electrons preionized diffuse discharge plasma. The removal efficiency from contaminant increased with the time of treatment increased from 5 to 20 minutes. Optical UV-IR spectroscopy was used for gathering information about the transmittance of aqueous solutions before and after treatment. The experimental results illustrated that transmittance of aqueous solution of methylene blue after 20 minutes of treatment by diffuse discharge plasma increased by ~ 30 %.
Coatings based on chromium carbide fabricated by an arc sputtering of graphite and Cr-Al(Si) targets
Authors: Rubshtein A P , Vladimirov A B , Plotnikov S A
Published: November 2019

Single CrAlC, CrAlSiC and multilayer [CrAlC/a-C]n, [CrAlSiC/a-C]n coatings have been fabricated and investigated. Joint use of arc plasma source with Cr-Al(Si) cathode and pulsed arc plasma source with graphite cathode was applied to single coatings deposition. Diamond-like a-C layers alternate with CrAl(Si)C in multilayer coatings. The doping of CrAlC with silicon is accompanied by an increase in their crystallinity due to the formation of silicon carbide particles. Structural changes make CrAlSiC films harder with a low friction coefficient and a high resistance to plastic deformation. The multilayer coatings are crack resistant.
Chemical transformations initiated by gas discharges in aqueous solutions
Authors: Shutov D A , Sungurova A V , Manukyan A C , Ivanov A N , Rybkin V V
Published: November 2019

The kinetic regularities of the processes of oxidation-reduction of chromium ions under the action of a direct current discharge of atmospheric pressure in air, oxygen and argon on an aqueous solution of potassium dichromate at currents of 20–60 mA and concentrations 0.092–0.4 mmol·l−1 are investigated. The solution served as the cathode of the discharge. It was found that the effect of a discharge in any gas on a solution stimulates the reversible Cr6+↔Cr3+ reactions of oxidation-reduction of chromium ions. The apparent constants of the rates of oxidation and reduction and their dependence on the discharge current and initial concentration are found. The energy efficiency of the process is estimated. It is shown that the discharge in argon is most effective for carrying out the reduction process.
Electroplasma installation for producing high-temperature silicate melts
Authors: Volokitin O G , Shekhovtsov V V , Skripnikova N K , Volokitin G G , Vlasov V A
Published: November 2019

The paper presents the design of an electroplasma installation for producing the high-temperature silicate melts. The optimal operating modes of the screw feeder (from 12.3 kg·h−1 to 25.4 kg·h−1) were established to ensure the production of a homogeneous high-temperature silicate melt. The design of electroplasma installation with a closed volume to produce highly viscous melts with the viscosity values of more than 105 Pa·s is proposed.
Synthesis of Ni-Al intermetallic surface alloys produced by using a low-energy high-current electron beam
Authors: Yakovlev E V , Markov A B , Shepel D A , Solovyov A V , Petrov V I
Published: November 2019

Ni-Al surface alloy electron beam synthesis results are presented. Surface alloy was formed on a carbon steel substrate by multilayer Ni-Al system deposition and subsequent one pulse low-energy high-current electron beam (LEHCEB) treatment in single vacuum cycle. It is shown that surface alloy containing mainly intermetallic phase NiAl is formed as a result of one pulse LEHCEB treatment. It is established that NiAl surface alloy microhardness and wear resistance are higher in comparison to steel substrate parameters.
Coincidence of increasingly volatile winters in China with Arctic sea-ice loss during 1980–2018
Authors: Chen Yang , Liao Zhen , Zhai Panmao
Published: November 2019

Despite intense discussions on the recent boom of mid-latitude wintertime cold extremes, co-variations of warm and cold extremes, i.e. winter temperature volatility, has garnered substantially less attention. Apart from using temperature extremes’ frequency and intensity, we also define ‘temperature whiplash’, which depicts rapid switches between warm and cold extremes, to measure winter temperature volatility in China. Results show that Northeast-, Northwest-, Southwest-, Southeast-China and the Yangtze River Valley have experienced increasingly volatile winters after 1980, co-occurring with precipitous decline in Arctic sea-ice. This enhanced volatility has a strong expression in significant increases in temperature whiplash events, with some hotspots also seeing both warm and cold extremes become more frequent and/or intense. An observation-based detection analysis highlights the dominance of intrinsic atmospheric variability over both anthropogenic warming and sea-ice decline during 1980–2018 in driving winters in China to be more volatile over this period.
Is excess faster than deficient? A molecular-dynamics study of oxygen-interstitial and oxygen-vacancy diffusion in CeO2
Authors: Waldow Stephan P , De Souza Roger A
Published: November 2019

The diffusivity of oxygen interstitials (D
i) and of oxygen vacancies (D
v) in fluorite-structured CeO2 was studied by means of classical molecular dynamic simulation techniques. Simulations were performed on cells that were either oxygen abundant or oxygen deficient at temperatures 1500 ≤ T / K ≤ 2000 for defect site fractions 0.18% ≤ n
i/v ≤ 9.1%. In general, we found that at a given temperature T and defect site fraction n
i/v the vacancy diffusivity D
v was higher than the interstitial diffusivity D
i. Isothermal values of D
i and D
v were constant at low defect site fractions (n
i/v < 0.91%), but the behaviour diverged at higher n
i/v: whereas D
v decreased at higher n
v, D
i increased at higher n
i. The analysis also yielded, as a function of n
i/v, activation enthalpies (ΔH
mig) and entropies (ΔS
mig) of vacancy migration and of interstitial migration. A constant value of

Δ

H

mig
,
v

≈

0.6 eV was found for low n
v, with increases in

Δ

H

mig
,
v

observed for n
v > 0.91%. For low n
i a constant value of

Δ

H

mig
,
i

≈

1.4 eV was found, with a surprising decrease in

Δ

H

mig
,
i

for n
i > 0.91%. The effect of dopants on the behaviour of the defect diffusivities was also studied. Doping with Gd3+ had a detrimental effect on vacancy diffusion, with a slight decrease in D
v and an increase in

Δ

H

mig
,
v

being observed. Donor doping with Nb5+, in contrast, was beneficial, resulting in higher D
i and a decrease in

Δ

H

mig
,
i

. We suggest that the migration mechanism of oxygen interstitials in CeO2, non-collinear interstitialcy, is responsible for the lower defect diffusivity and higher migration barrier.
Measuring Worker Protection Using Leximetrics: Illustrating a New Approach in Four Asia-Pacific Countries
Authors: Mahy Petra , Mitchell Richard , Sutherland Carolyn , Gahan Peter , O’Donnell Anthony , Cooney Sean , Anderson Gordon , Mao Lingfeng , Stewart Andrew
Published: November 2019

This Article introduces the Worker Protection Index (WPI), a new measure for quantitative cross-national comparison of the strength of worker protection provided by law. After presenting an overview and critique of existing labor regulation indices, the Article outlines the conceptual and methodological innovations used in order to develop the WPI. The WPI is wider in scope than many other comparable indices and arguably is more sensitive to variance in labor regulation systems around the world. We then briefly present some initial coding results for Australia, China, Indonesia, and New Zealand, illustrating the impact of our innovations by contrasting these findings with the Cambridge Centre for Business Regulation (CBR) Labour Regulation Index (LRI).
A new species of Eogruidae (Aves: Gruiformes) from the Miocene of the Linxia Basin, Gansu, China: Evolutionary and climatic implications
Authors: Musser Grace , Li Zhiheng , Clarke Julia A
Published: November 2019

Despite having one of the most robust fossil records within core-gruiform birds (rails, cranes, and allies), the biogeographic history of Gruidae (cranes) and key drivers of diversification within this group remain largely unknown. The Eogruidae of Eurasia represent some of the earliest known crane-like fossils. Here, we present description of a new species represented by a well-preserved specimen of a foot from the late Miocene (7–6.5 mya) Liushu Formation of Linxia Basin, Gansu, China. It is the only eogruid fossil that has been found in this formation and is the first eogruid known from northwest China. Linxia Basin is located along the margin of the northeastern Tibetan Plateau, which allows for new insight into Miocene dispersal of the Eogruidae and potential climatological and geological connections. It is also the first specimen with an associated tarsometatarsus and nearly complete phalanges, including a claw, which provides further morphological information on this taxon. Referral of the new specimen to Eogruidae is based on extreme reduction of the trochlea of metatarsal II, which is most similar to the condition present in the eogruid subclade traditionally termed Ergilornithidae.
The Western Jihadi Subculture and Subterranean Values
Authors: Cottee Simon
Published: November 2019

This article draws on the criminological work of Gresham Sykes and David Matza as a starting point for theorizing the nature and appeal of the western jihadi subculture, defined here as a hybrid and heavily digitized global imaginary that extols and justifies violent jihad as a way of life and being. It suggests that at the centre of this subculture are three focal concerns: (1) Violence and Machismo; (2) Death and Martyrdom; and (3) Disdain of the Dunya. More critically, it argues that these three focal concerns have immediate counterparts in the shadow values of the wider society with which western jihadists are in contention. This argument has important implications for debates over radicalization and the attractions of jihadist activism.
Building inclusive community activism and accountable relations through an intersecting inequalities approach
Authors: Shaw Jackie , Howard Jo , Franco Erika López
Published: November 2019

Community development interventions can generate collective identities, foster community activism and build more accountable relations between marginalized groups and duty-bearers 1. Yet, our previous research shows meaningful inclusion of the most disadvantaged groups is not sustainable unless the intersecting inequalities at the root of poverty and marginalization are understood and addressed. This article draws on participatory action research (PAR) processes conducted between 2016 and 2017 in Egypt, Ghana, India, South Africa and Uganda, which worked through local partners to engage directly with groups affected by deep inequalities and unaccountable dynamics. Collaboratively, we explored how intersecting inequalities play out in people’s everyday lives to drive poverty and marginalization and the elements necessary for participatory processes to catalyze community activism and build pathways towards accountability. In this article, we operationalize the concept of intersecting inequalities, in order to understand the complexity of ‘community’ in different contexts and the contribution of this approach to inclusive community development. Finally, we draw lessons about how to navigate the intrinsic tensions between recognizing difference and building community activism for accountability.
Dose-specific Effectiveness of 7- and 13-Valent Pneumococcal Conjugate Vaccines Against Vaccine-serotype Streptococcus pneumoniae Colonization in Children
Authors: Lewnard Joseph A , Givon-Lavi Noga , Dagan Ron
Published: November 2019

Background

Reduced-dose pneumococcal conjugate vaccine (PCV) schedules are under consideration in countries where children are recommended to receive 3 doses. Whereas PCV-derived protection against vaccine-serotype colonization is responsible for herd effects of vaccination, dose-specific PCV effectiveness against colonization endpoints is not known. We aimed to assess the performance of differing PCV schedules against vaccine-serotype colonization in children.

Methods

From 2009–2016, we monitored pneumococcal carriage in southern Israel, where children should receive PCV at ages 2 months, 4 months, and 12 months (2 primary [p] +1 booster [b] schedule). We analyzed nasopharyngeal swabs and vaccination histories from 5928 children aged 0–59 months without symptoms of diseases potentially attributable to pneumococci. Matching individuals on age, sex, ethnicity, visit timing, and recent antibiotic receipt, we measured schedule-specific 7-valent PCV (PCV7) and 13-valent PCV (PCV13) effectiveness against vaccine-serotype colonization in a modified case-control framework. We sampled from the distribution of all possible case-control match assignments for statistical analyses.

Results

Receiving 2 primary-series PCV13 doses conferred 53% (95% confidence interval [CI], 32–67%) protection against PCV13-serotype colonization at ages ≤12 months; 1 primary-series dose was not protective. A 2p+1b PCV13 series conferred 40% (95% CI, 4–67%) and 62% (95% CI, 33–83%) protection against PCV13-serotype colonization at ages 13–24 months and 25–59 months, respectively. Estimates suggested greater PCV13-conferred protection against PCV7-targeted serotypes than the 6 PCV13-only serotypes. As compared to children receiving 2p+1b PCV13 dosing, those receiving 1p+1b and 2p+0b schedules experienced 2.05-fold (95% CI, 1.12–5.00) and 3.33-fold (95% CI, 2.28–4.93) greater odds, respectively, of vaccine-serotype pneumococcal colonization at ages 13–24 months.

Conclusions

Our results demonstrate real-world effectiveness of 2p+1b PCV dosing against vaccine-serotype colonization. Reduced-dose schedules may confer lower protection against vaccine-serotype carriage during and beyond the first year of life.
Investigating the Natural Mortality of Aphis gossypii (Hemiptera: Aphididae) on Cotton Crops in Tropical Regions Using Ecological Life Tables
Authors: Chamuene António , Araújo Tamíris Alves De , Lopes Mayara Cristina , Ramos Pereira Renata , Berger Paulo Geraldo , Picanço Marcelo Coutinho
Published: November 2019

Studies on the natural factors contributing to pest regulation are fundamental to developing efficient integrated pest management programs. Chemical control is the main management method used for pests [e.g., Aphis gossypii (Glover)]. The studies of pest management with chemical control provide information that can be incorporated into integrated pest management programs to promote more sustainable pest control approaches. Here, we report the critical stages of A. gossypii and its abiotic and biotic natural mortality factors in cotton crops as a function of plant phenology using a life table. The critical stages of A. gossypii were the first and fourth instars. Together, the abiotic and biotic factors caused 94.31% of the mortality in the A. gossypii populations in cotton crops with plants in the vegetative, flowering, and fruiting stages. The key mortality factors were rainfall and predation. Syrphidae Allograpta exotica (Wiedemann) (Diptera: Syrphidae) and Chrysopidae Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae) larvae, many Coccinellidae species Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae), Eriopsis connexa (Germar) (Coleoptera: Coccinellidae), Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), Hippodamia convergens (Guérin-Meneville) (Coleoptera: Coccinellidae), Scymnus rubicundus (Erichson) (Coleoptera: Coccinellidae) and Stethorus punctillum (Weise) (Coleoptera: Coccinellidae), one Anthocoridae species Orius insidiosus (Say) (Hemiptera: Anthocoridae), and individuals from the Araneidae family were responsible for the predation of A. gossypii. The results obtained in this study provide support for the idea that efforts to preserve natural enemies (e.g., predators) and rainfall monitoring should be adapted due to their importance for the regulation of A. gossypii populations in all the phenological stages of cotton in tropical regions.
High-level expression of an acidic thermostable xylanase in Pichia pastoris and its application in weaned piglets
Authors: Wang Jian , Liu Yajing , Yang Yongzhi , Bao Chengling , Cao Yunhe
Published: November 2019

An acidic thermostable xylanase (AT-xynA) which was stable at low pH and high temperature was considered to have great potential in animal feed. For large-scale production, AT-xynA activity was enhanced about 1-fold in Pichia pastoris by constructing a double-copy expression strain in this study. Furthermore, impacts of different AT-xynA levels on growth performance, nutrient digestibility, short-chain fatty acids, and bacterial community in weaned piglets were determined. Compared with the control group, ADFI and ADG were higher for the pigs fed 4,000 or 6,000 U/kg AT-xynA (P < 0.05). AT-xynA supplementation also significantly increased the digestibility of OM, GE, and DM (P < 0.05). AT-xynA supplementation increased the concentrations of acetate in ileal (P < 0.01) and cecal digesta (P < 0.05). Isobutyrate (P < 0.05) and valerate (P < 0.05) concentrations in colonic digesta also significantly increased compared with the control group. AT-xynA supplementation increased the abundance of Lactobacillus in the ileal, cecal, and colonic digesta of weaned piglets (P < 0.05). AT-xynA alleviated anti-nutritional effects of nonstarch polysaccharides (NSP) by preventing the growth of Pateurella and Leptotrichia in the ileum (P < 0.05). AT-xynA increased the abundance of NSP-degrading bacteria, such as Ruminococcaceae, Prevotella in the cecum and colon (P < 0.05). In summary, AT-xynA addition could improve the growth performance of weaned piglets by altering gut microbiota.
Pathological consequences of the unfolded protein response and downstream protein disulphide isomerases in pulmonary viral infection and disease
Authors: Chamberlain Nicolas , Anathy Vikas
Published: November 2019

Protein folding within the endoplasmic reticulum (ER) exists in a delicate balance; perturbations of this balance can overload the folding capacity of the ER and disruptions of ER homoeostasis is implicated in numerous diseases. The unfolded protein response (UPR), a complex adaptive stress response, attempts to restore normal proteostasis, in part, through the up-regulation of various foldases and chaperone proteins including redox-active protein disulphide isomerases (PDIs). There are currently over 20 members of the PDI family each consisting of varying numbers of thioredoxin-like domains which, generally, assist in oxidative folding and disulphide bond rearrangement of peptides. While there is a large amount of redundancy in client proteins of the various PDIs, the size of the family would indicate more nuanced roles for the individual PDIs. However, the role of individual PDIs in disease pathogenesis remains uncertain. The following review briefly discusses recent findings of ER stress, the UPR and the role of individual PDIs in various respiratory disease states.
Monitoring the Resistance of the Citrus Red Mite (Acari: Tetranychidae) to Four Acaricides in Different Citrus Orchards in China
Authors: Pan Deng , Dou Wei , Yuan Guo-Rui , Zhou Qi-Hao , Wang Jin-Jun
Published: November 2019

The citrus red mite, Panonychus citri (McGregor), is an important spider mite pest in citrus producing areas. Owing to long-term acaricide exposure, resistance has evolved rapidly in recent years. To evaluate the extent of resistance, seven field mite populations sampled from various geographical locations in China during 2015–2018 were tested using the leaf-dip bioassay method to determine their susceptibilities to four acaricides. In comparison with the susceptible strain maintained in the laboratory, low or moderate levels of fenpropathrin resistance, while no resistance to abamectin or cyflumetofen, were found among populations sampled from Liangping, Wanzhou, Daying, and Anyue in Southwestern China during the test period. High levels (>1,000-fold, with LC50 values that were greater than the recommended concentration) of resistance to fenpropathrin had evolved in field populations from Southern China, including Guilin, Nanning, and Yuxi, when compared with that of the susceptible strain. Populations from Guilin and Nanning also evolved high resistance levels to abamectin (1,088-fold and 1,401-fold) and cyflumetofen (2,112-fold and 9,093-fold). All the populations sampled in 2018 showed a moderate or high resistance to bifenazate. Generally, field populations of citrus red mites from Southwestern China were more sensitive to the tested acaricides than those of Southern China. The data provide a foundation for developing acaricide resistance management strategies in these regions.
Efficiency of Food-Based Attractants for Monitoring Tephritid Fruit Flies Diversity and Abundance in Mango Systems Across Three West African Agro-Ecological Zones
Authors: Hanna Rachid , Gnanvossou Désiré , Goergen Georg , Bokonon-Ganta Aimé H , Mohamed Samira A , Ekesi Sunday , Fiaboe Komi K M , Agnontchémè Abiola I
Published: November 2019

Food baits are effective and widely used tools for monitoring diversity and abundance of tephritid fruit flies. Four food-baits—Nulure, BioLure, Mazoferm at 3 and 6%, and Torula yeast—were used in multi-lure traps over a 4-yr period in mango orchards in three Benin agro-ecological zones (AEZ) representing a large swath of environments in western Africa. Twelve tephritid fruit fly species were captured during the trials, with the highest richness in the Forest Savannah Mosaic (FSM), followed by the Southern Guinea Savannah (SGS), and the Northern Guinea Savannah (NGS) AEZ. Despite previous reports of displacement, the native species Ceratitis cosyra remained the dominant tephritid species in mango orchards in the NGS, with the invasive and exotic species Bactrocera dorsalis dominating the tephritid fauna in the SGS and FSM. Torula yeast captured the greatest number of fruit flies in each AEZ. Mazoferm-3% captures were similar to Torula yeast, except for lower captures in the NGS where it tended to harden. The rank order of relative efficiency indices (REI) of the food baits (relative to Torula yeast) is Mazoferm-3% > Nulure > Mazoferm-6% and BioLure. The latter captured more Ceratitis spp. than all the other baits, particularly at very low Ceratitis spp. abundance. To our knowledge, the study is the first to report relative efficiency indices for the selection of food baits in monitoring diversity and abundance of fruit flies. Ecological and practical implications for the use of food baits in comparison with male lures are discussed.
Susceptibility of Euschistus heros and Dichelops furcatus (Hemiptera: Pentatomidae) to Selected Insecticides in Brazil
Authors: Somavilla Junior C , Reis Alexandre C , Gubiani Patricia da S , Godoy Daniela N , Stürmer Glauber R , Bernardi Oderlei
Published: November 2019

Euschistus heros (Fabricius, 1798) and Dichelops furcatus (Fabricius, 1775) are key pests of agricultural crops in Brazil. Chemical insecticides are the main control tactic used against these species. Here, we investigated the susceptibility of E. heros and D. furcatus from distinct regions to the mains insecticides used to stink bugs control in Brazil. Field populations of these species were collected throughout the 2017–2019 crop seasons and insects were exposed to insecticides in dip-test bioassays using fresh green bean pods. Populations of E. heros exhibited low variation in the susceptibility to acephate (LC50 = 172.2 to 1,008 µg a.i. per ml), and thiamethoxam (LC50 = 28.8 to 433.9 µg a.i. per ml); resistance ratios were less than 5.9- and 15.1-fold, respectively. In contrast, these populations had higher variation in the susceptibility to bifenthrin (LC50 = 26.7 to 636.1 µg a.i. per ml) and lambda-cyhalothrin (LC50 = 10.0 to 636.1 µg a.i. per ml); resistance ratios reaching 23.8- and 63.6-fold, respectively. Susceptibility monitoring data indicated a higher susceptibility of E. heros to the manufacturers field-recommended rates of acephate, lambda-cyhalothrin + thiamethoxam, and bifenthrin + acetamiprid than lambda-cyhalothrin. Populations of D. furcatus exhibited low variation in the susceptibility to acephate (LC50 = 219.2 to 614.1 µg a.i. per ml), bifenthrin (LC50 = 62.8 to 197.4 µg a.i. per ml), and lambda-cyhalothrin (LC50 = 189.5 to 2,538 µg a.i. per ml); resistance ratios were less than 13.4-fold. In summary, populations of E. heros are less susceptible to pyrethroids, while populations of D. furcatus have similar susceptibility to the insecticides evaluated.