bluuebunny/crossref_metadata_2025 huggingface dataset:
Short cylindrical nozzles in a jet-driven Helmholtz oscillator
Authors: Abdrashitov A. A. , Marfin E. A.
Published: July 2020

The present paper elaborates on the experimental study of jet-excited pressure fluctuations in a Helmholtz oscillator model with two openings in a cylindrical cavity. The length of the cylindrical nozzle in the front cover ℓN normalized by the nozzle diameter dN was ℓN/dN = 0.125, 0.33, 0.47, and 0.67. The diameter of the outlet opening in the back cover dOUT was in the range dOUT/dN = 1–2.5. The length of the cylindrical cavity LCH determined the jet length LJET in the spacing between the covers, LCH/dN = 0.5–3.5. The amplitude–frequency spectra were studied when the oscillator configuration was changed in the indicated intervals. From the generation amplitude, the best ratio of the sizes of the nozzle, chamber, and outlet was determined. The appearance of the jet tone of the hole and the alternation of acoustic modes were observed with a smooth increase in the Reynolds number to ∼8 · 104. The measurements showed very high amplitude of pressure fluctuations in an oscillator with a short nozzle and a short chamber at a significant jet velocity. A slight increase in the length of the chamber led to a rapid decrease in the generation amplitude. It is determined that the tone frequency is usually much lower than the resonance frequency in the chamber. Moreover, the tone frequency gradually increases with increasing jet velocity, while the resonance frequency remains unchanged, close to the natural frequency of the cavity chamber.
Direct numerical simulation of drag reduction by spanwise oscillating dielectric barrier discharge plasma force
Authors: Altıntaş A. , Davidson L. , Peng S.-H.
Published: July 2020

DBD (dielectric barrier discharge) plasma actuators have in recent years become increasingly attractive in studies of flow control due to their light structures and easy implementation, but the design of a series of actuators enabling drag reduction depends on many parameters (e.g., the length of the actuator, the space between actuators, and voltage applied) and remains a significant issue to address. In this study, velocities created by the DBD plasma actuators in stagnant flow obtained by the numerical model are compared with experimental results. Then, a DNS study is carried on, and spanwise oscillated DBD plasma actuators are examined to obtain a drag reduction in a fully developed turbulent channel flow. This study connects the conventional spanwise oscillated force in drag reduction studies with DBD plasma actuators. While the former is one of the most successful applications for the drag reduction, the latter is a most promising tool with its light and feasible structure.
Influence of space charge on the conductivity of nanocrystalline SrTiO3
Authors: Wu Yifeng , Bowes Preston C. , Baker Jonathon N. , Irving Douglas L.
Published: July 2020

A grand canonical multiscale space-charge model has been developed to study and predict the electrical properties of polycrystalline perovskites with complex defect chemistries. This model combines accurate data from hybrid exchange-correlation functional density functional theory calculations (defect formation energies, resultant grand canonical calculations of defect concentrations, and ionization states) with finite-element simulation of the electric field and its coupling to defect redistribution and reionization throughout the grain. This model was used to simulate the evolution of the oxygen partial pressure-dependent conductivity of polycrystalline acceptor-doped strontium titanate as the grain size decreases, and the results were compared to previous experiments. These results demonstrate that as the grain size is reduced from the microscale to nanoscale, the experimentally observed disappearance of ionic conductivity and forward shift of the oxygen partial pressure of the n–p crossover are successfully reproduced and explained by the model. Mechanistically, the changes to conductivity stem from the charge transfer from the grain boundary core into the grain interior, forming a space-charge layer near the grain boundary core that perturbs the local defect chemistry. The impact of the grain size on the electrical conductivity and the underlying defect chemistry across the grain are discussed. In addition to the findings herein, the model itself enables exploration of the electrical response of polycrystalline semiconductor systems with complex defect chemistries, which is critical to the design of future electronic components.
First-principles study on the effect of Sn doping in Cu2S—Acanthite phase as a substitute to low chalcocite for modeling complex doping
Authors: Barman Sajib K. , Huda Muhammad N.
Published: July 2020

The major challenge in the application of Cu2S, as a solar absorber for photovoltaic, is its excessive Cu-vacancy formation tendency within the crystal structure that makes it a degenerate semiconductor. A recent study on Ag alloyed Cu2S acanthite phase has shown a reduced Cu-vacancy formation and a high Cu diffusion barrier. Though low chalcocite is the experimentally known ground state phase at room temperature, its low crystallinity makes it computationally expensive for complex doping modeling. In this work, we first establish the structural correspondence between a newly predicted acanthite and experimentally known low chalcocite phases of Cu2S. This study shows that the acanthite crystal structure of Cu2S can be used to model complex doping in the low chalcocite. The simulated pair distribution functions and diffusions of Cu at room temperature in acanthite and low chalcocite phases of Cu2S show that they have similar structural behavior. Pristine band structures and density of state plots of these two phases also show similarity. Next, we report density functional theory based first-principles investigations of Cu2−xSnxS systems for x = 0 to 0.31 in the acanthite phase for thermodynamic, electronic, and optical properties. We have found that Sn doping coupled with Cu vacancies creates charge-neutral defects and results in higher photoabsorption in the visible light spectra. It was found from these detailed studies that a low concentration of Sn doping is preferable. Then, Sn doping and Cu-vacancy related defects in low chalcocite Cu2S are also studied. Ab initio molecular dynamics simulations show that these compound defects in Cu2S do not negatively affect Cu diffusion inside the crystal. We propose a possible route to synthesize Sn doped acanthite like Cu2S.
Classification of platinum nanoparticle catalysts using machine learning
Authors: Parker A. J. , Opletal G. , Barnard A. S.
Published: July 2020

Computer simulations and machine learning provide complementary ways of identifying structure/property relationships that are typically targeting toward predicting the ideal singular structure to maximize the performance in a given application. This can be inconsistent with experimental observations that measure the collective properties of entire samples of structures that contain distributions or mixture of structures, even when synthesized and processed with care. Metallic nanoparticle catalysts are an important example. In this study, we have used a multi-stage machine learning workflow to identify the correct structure/property relationships of Pt nanoparticles relevant to oxygen reduction, hydrogen oxidation, and hydrogen evolution reactions. By including classification prior to regression, we identified two distinct classes of nanoparticles and subsequently generated the class-specific models based on experimentally relevant criteria that are consistent with observations. These multi-structure/multi-property relationships, predicting properties averaged over a large sample of structures, provide a more accessible way to transfer data-driven predictions into the lab.
Non-conventional force fields for applications in spectroscopy and chemical
reaction dynamics
Authors: Koner Debasish , Salehi Seyedeh Maryam , Mondal Padmabati , Meuwly Markus
Published: July 2020

Extensions and improvements of empirical force fields are discussed in view of applications to computational vibrational spectroscopy and reactive molecular dynamics simulations. Particular focus is on quantitative studies, which make contact with experiments and provide complementary information for a molecular-level understanding of processes in the gas phase and in solution. Methods range from including multipolar charge distributions to reproducing kernel Hilbert space approaches and machine learned energy functions based on neural networks.
Thrust generation by pitching and heaving of an elastic plate at low Reynolds number
Authors: Manjunathan Sujyesh Aanandh , Bhardwaj Rajneesh
Published: July 2020

We computationally study thrust generation and propulsive characteristics of an elastic plate pitching and/or heaving in free stream laminar flow. The pitching is considered about the leading edge, and the Reynolds number based on the plate length and free stream velocity is 150. An in-house fluid–structure interaction (FSI) solver is employed to simulate the large-scale flow-induced deformation of the structure along with active pitching and heaving in two-dimensional coordinates. The FSI solver utilizes a partitioned approach to strongly couple a sharp-interface immersed boundary method based flow solver with an open-source finite-element structural dynamics solver. We elucidate the mechanism of the thrust generation in the rigid and elastic plate by comparing the time-variation of thrust and work done by the plate, together with the wake signatures in the downstream. The time variation of the thrust is explained using first-order scaling arguments. The computed thrust as a function of pitching frequency for the rigid pitching plate shows a similar trend as compared to the published data of rigid foils, while the elastic plate exhibits a strong influence of the flow-induced deformation of the plate. They both exhibit reverse von Kármán-like vortex shedding in the downstream. We quantify the differences in propulsive characteristics of these two plate types as a function of pitching frequency. We found that there lies an optimum pitching frequency for the elastic plate for efficient propulsion, while the rigid one outperforms the elastic plate at larger pitching frequency. This is due to the fact that the elastic plate locks in to a higher mode of vibration at a larger pitching frequency. Furthermore, the influence of mass ratio, flexural rigidity, pitching amplitude, and Reynolds number on the performance of the elastic plate is also investigated. Finally, we study the combined effect of pitching and heaving on the propulsive performance. The pitching frequency for the maximum efficiency is lesser for the combined heaving and pitching plate as compared to only heaving or only pitching. Our results provide fundamental insights into the propulsive characteristics of the elastic pitching and/or heaving plates, which could help design autonomous underwater vehicles.
Acoustic tweezing for both Rayleigh and Mie particles based on acoustic focused petal beams
Authors: Jia Yu-Rou , Wu Da-Jian , Yao Jie , Wei Qi , Xu Zheng , Liu Xiao-Jun
Published: July 2020

Acoustic tweezers (ATs) have been extensively exploited in physics, biology, chemistry, and medical medicine. However, previous ATs are limited by complex designs and cumbersome configurations, and the stable manipulation of Mie particles remains challenging. Here, an AT based on acoustic focused petal beams (AFPBs) is proposed to realize 2D stable manipulations of both Rayleigh and Mie particles in water. The AFPBs are generated by artificial structure plates (ASPs) engraved with two kinds of discrete curved slits. It is found that the bright petals of AFPBs are flexibly modulated by arranging the sectors of curved slits on ASP, and the central zero-intensity region encircled by bright petals is increased with the number of petals. Then, the acoustic radiation forces of the AFPBs with 2 and 10 petals acting on the Rayleigh and Mie particles are further studied, respectively, and a force equilibrium position is found in both cases. Finally, two ASP samples are fabricated to experimentally verify the generations of AFPBs, and the 2D stable trappings and movements of both Rayleigh and Mie particles are realized by AFPBs. This miniaturized AT is beneficial to practical applications in material fabrication, drug delivery, and tissue engineering.
The role of contaminations in ion beam spectroscopy with freestanding 2D materials: A study on thermal treatment
Authors: Niggas A. , Schwestka J. , Creutzburg S. , Gupta T. , Eder D. , Bayer B. C. , Aumayr F. , Wilhelm R. A.
Published: July 2020

As surface-only materials, freestanding 2D materials are known to have a high level of contamination—mostly in the form of hydrocarbons, water, and residuals from production and exfoliation. For well-designed experiments, it is of particular importance to develop effective cleaning procedures, especially since standard surface science techniques are typically not applicable. We perform ion spectroscopy with highly charged ions transmitted through freestanding atomically thin materials and present two techniques to achieve clean samples, both based on thermal treatment. Ion charge exchange and energy loss are used to analyze the degree of sample contamination. We find that even after cleaning, heavily contaminated spots remain on single layer graphene. The contamination coverage, however, clusters in strand-like structures leaving large clean areas. We present a way to discriminate clean from contaminated areas with our ion beam spectroscopy if the heterogeneity of the surface is increased sufficiently enough. We expect a similar discrimination to be necessary in most other experimental techniques.
On fluid flow and heat transfer of turbulent boundary layer of pseudoplastic fluids on a semi-infinite plate
Authors: Yao Chanjuan , Li Botong , Si Xinhui , Meng Yahui
Published: July 2020

The boundary layer of a pseudoplastic fluid on a semi-infinite plate for a high generalized Reynolds number is analyzed. Based on the Prandtl mixing length theory, the turbulent region is divided into two regions. The coupled momentum and temperature equations, with a generalized thermal conductivity model, have made the process of finding the analytical solutions much difficult. By using the similarity transformation, the equations are converted to four ordinary differential equations constrained by ten boundary conditions. An interesting technique of scaling and translation of the calculation domain of one region into another is used to make the system of equations easier to solve. It is found that the fluid with a smaller power-law index, associated with a thinner velocity boundary layer thickness, processes a lower friction coefficient. Furthermore, the increase in the Reynolds number causes a thinner velocity boundary layer and a decreasing friction coefficient on the wall. Changes in temperature occur more slowly near the plate surface with a rise in the power-law index and a decrease in the Reynolds number.
An investigation on the disturbance evolution and the transition by resonant-triad interactions with a side-frequency disturbance in a boundary layer
Authors: Zhang Yongming , Zhou Wenqiang , Chen Xiangzhen
Published: July 2020

In practical engineering problems, there are always side-frequency components whose frequencies are close to those of the dominant-frequency waves. In this paper, the parabolized stability equations are employed to study the influence of a side-frequency component on the development of a dominant-frequency disturbance and on the transition by resonant-triad interactions. The numerical results are qualitatively consistent with the experimental data and the asymptotic analysis results. It is found that the resonant-triad waves and the mean flow distortion cannot trigger transition by themselves. We identify a new mechanism, which we refer to as the Steady-Spanwise-Waves-Working (SSWW) mechanism, which is necessary to cause transition, in that the steady spanwise waves generated by the nonlinear interaction between the pair of three-dimensional waves play an indispensable role. For the transition caused by resonant-triad interactions with a side-frequency component, the side-frequency wave makes transition occur earlier, and the relative amplitude rather than the absolute amplitude of the side-frequency disturbance plays the essential role in the transition advance. If the relative amplitude reaches the threshold level of 40%, the transition location can be affected substantially. In this kind of transition, the SSWW mechanism still works, and the side-frequency perturbation enhances the effects of the SSWW mechanism such that the transition occurs earlier.
Development of a quartz crystal microbalance diagnostic for measuring material erosion and deposition on the first wall in EAST
Authors: Zhang Y. , Peng J. , Ding R. , Xie H. , Mu L. , Chen J. L.
Published: July 2020

A quartz crystal microbalance (QMB) diagnostic system has been established in Experimental Advanced Superconducting Tokamak (EAST) for real-time and in situ measurements of erosion and deposition rates of plasma-facing materials at the first wall. A ∼70 nm aluminum (Al) film has been coated on the QMB crystal surface to measure the erosion rate by charge exchange neutral particles. Dual sensors of the QMB system have been used with a closed sensor for reference. The stability and light sensitivity of the QMB system have been tested in the lab, demonstrating its feasibility on the application of EAST experiments. The QMB system with cooling water has been successfully applied in the 2018 EAST campaign. The net erosion thickness measured by the QMB has been well validated by thickness measurements using the Rutherford backscattering spectrometry. The developed QMB systems can help us to understand the physics processes of material erosion and deposition at main chamber walls for long pulse operations in EAST.
Challenges, myths, and opportunities of electron microscopy on halide perovskites
Authors: Chen Shulin , Gao Peng
Published: July 2020

Organic–inorganic hybrid perovskites (OIHPs) have attracted extensive research interest as promising candidates for optoelectronic applications such as solar cells. Transmission electron microscopy (TEM)-based characterizations hold the key to revealing the morphological, microstructural, physical, and chemical information of OIHPs. However, their extreme sensitivity to the electron beam illumination usually inhibits us from obtaining the intrinsic information or even leads to significant artifacts. In this perspective, recent TEM studies on OIHPs are reviewed, wherein the discussions focus on how the electron beam destabilizes the structure of OIHPs and how to mitigate such effects as well as avoid misinterpretations. This perspective aims to catch researchers' attention on the beam sensitivity of OIHPs, guide the TEM characterization, and inspire electron microscopy development to reveal the working principle and failure mechanism of OIHPs.
Wake and thermal characteristics for cross-buoyancy mixed convection around and through a porous cylinder
Authors: Yu Shimin , Tang Tingting , Li Jianhui , Yu Peng
Published: July 2020

The influence of cross buoyancy on the steady flow and mixed convective heat transfer around and through a porous cylinder with internal heat generation is investigated numerically. Based on the Darcy–Brinkman–Forchheimer extended porous medium model, the finite volume method is applied to investigate the wake structure and thermal characteristics in terms of the streamlines, asymmetry of recirculating wakes, temperature distribution, and average Nusselt number. The ranges chosen for the Reynolds number (Re), Darcy number (Da), and Richardson number (Ri) are 5 ≤ Re ≤ 40, 10−6 ≤ Da ≤ 10−2, and 0 ≤ Ri ≤ 1, respectively. For certain ranges above, a pair of asymmetric recirculating wakes is observed, with the upper recirculating wake detached from and the lower one partially penetrating or also detached from the cylinder. The asymmetry of the recirculating wake increases with Ri but decreases with Re. Two or three regimes with the distinct asymmetric characteristics are identified over the range of Da investigated, depending on Re. For the heat transfer performance, cross buoyancy is found to have a certain impeditive impact on the average Nusselt number.
Structure refinement of black phosphorus under high pressure
Authors: Akahama Yuichi , Miyakawa Masashi , Taniguchi Takashi , Sano-Furukawa Asami , Machida Shinichi , Hattori Takanori
Published: July 2020

The structure refinement of black phosphorus was performed at pressures of up to 3.2 GPa at room temperature by powder neutron diffraction techniques. The bond lengths and bond angles between the phosphorus atoms at pressures were precisely determined and confirmed to be consistent with those of the previous single crystal x-ray analysis [A. Brown and S. Rundqvist, Acta Cryst. 19, 684 (1965)]. Although the lattice parameters exhibited an anisotropic compressibility, the covalent P1–P2 and P1–P3 bond lengths were almost independent of pressure and only the P3–P1–P2 bond angle was reduced significantly. On the basis of our results, the significant discrepancy in the bond length reported by Cartz et al. [J. Chem. Phys. 71, 1718 (1979)] has been resolved. Our structural data will contribute to the elucidation of the Dirac semimetal state of black phosphorus under high pressure.
Harvesting the lost photon by plasmonic enhanced hematite-upconversion nanocomposite for water splitting
Authors: Jiang Qianfan , Xie Xiangyu , Riley D. Jason , Xie Fang
Published: July 2020

Converting solar energy to chemical energy in the form of hydrogen via water splitting is one of the promising strategies to solve the global energy crisis. Hematite, a traditional semiconducting oxide photoelectrode, can only absorb UV and visible parts of the solar spectrum, losing 40% infrared energy. In this paper, we report a novel plasmonic enhanced water splitting photoanode based on hematite-lanthanide upconversion nanocomposites to harvest lost photons below the bandgap of hematite. NaYF4:Er, Yb upconversion nanoparticles can upconvert photons from 980 nm to 510 nm–570 nm within the bandgap of hematite. More importantly, a gold nanodisk array with a plasmonic peak centered ∼1000 nm can further boost the photocurrent by 93-fold. It is demonstrated that the excitation process of lanthanide upconversion nanoparticles can be significantly enhanced by plasmonic nanostructures and can thus improve the water oxidation activity via plasmonic enhanced upconversion and hot electron injection, respectively. This new promising strategy will pave the way for plasmonic enhanced lost photon harvesting for applications in solar energy conversion.
Persistence analysis of velocity and temperature fluctuations in convective surface layer turbulence
Authors: Chowdhuri Subharthi , Kalmár-Nagy Tamás , Banerjee Tirtha
Published: July 2020

Persistence is defined as the probability that the local value of a fluctuating field remains at a particular state for a certain amount of time, before being switched to another state. The concept of persistence has been found to have many diverse practical applications, ranging from non-equilibrium statistical mechanics to financial dynamics to distribution of time scales in turbulent flows and many more. In this study, we carry out a detailed analysis of the statistical characteristics of the persistence probability density functions (PDFs) of velocity and temperature fluctuations in the surface layer of a convective boundary layer using a field-experimental dataset. Our results demonstrate that for the time scales smaller than the integral scales, the persistence PDFs of turbulent velocity and temperature fluctuations display a clear power-law behavior, associated with a self-similar eddy cascading mechanism. Moreover, we also show that the effects of non-Gaussian temperature fluctuations act only at those scales that are larger than the integral scales, where the persistence PDFs deviate from the power-law and drop exponentially. Furthermore, the mean time scales of the negative temperature fluctuation events persisting longer than the integral scales are found to be approximately equal to twice the integral scale in highly convective conditions. However, with stability, this mean time scale gradually decreases to almost being equal to the integral scale in the near-neutral conditions. Contrarily, for the long positive temperature fluctuation events, the mean time scales remain roughly equal to the integral scales, irrespective of stability.
A hybrid structure light-emitting device based on a CsPbBr3 nanoplate and two-dimensional materials
Authors: Cheng Xing , Zang Zhihao , Yuan Kai , Wang Tingting , Watanabe Kenji , Taniguchi Takashi , Dai Lun , Ye Yu
Published: July 2020

High-crystalline halide perovskite nanostructures [such as nanowires and nanoplates (NPs)] provide good potential in realizing nanoscale solid light sources for on-chip optical communication, high-density storage, and life science applications. However, it remains a great challenge to fabricate nanoscale perovskite light-emitting devices using traditional fabrication methods because the perovskite nanomaterials will be dissolved in polar solvents. Developing new device configurations to enhance radiative recombination efficiency as well as device stability is one of the most important research topics in nanoscale perovskite light-emitting devices. Here, we demonstrate nanoscale perovskite electroluminescence (EL) using a single-crystalline CsPbBr3 NP as the active layer. The device is based on a hybrid capacitance structure, where an underlying few-layer graphene (FLG) electrode, a single-crystalline CsPbBr3 NP, a thin hexagonal boron nitride (hBN) flake, and another FLG top electrode are stacking in sequence, forming a van der Waals heterostructure. A strong EL emission peak with a narrow linewidth (∼1.09 nm) is observed at 2 K. Alternating current voltage/frequency-dependent EL spectra are studied in detail. We attribute the superior EL behavior of the as-fabricated nanoscale perovskite light-emitting devices to (1) the high-quality single-crystalline CsPbBr3 NPs synthesized, (2) the hBN encapsulation, which enhances the device stability by providing a large heat dissipation pathway for CsPbBr3 NP and protecting it from the polar solvents, (3) the capacitance structure, which facilitates the injection of both electrons and holes. Our work demonstrates a method to construct nanoscale perovskite (with well-defined geometry) light sources, providing an opportunity for realizing a nanoscale electrically driven perovskite laser.
Strong magnon–photon coupling within a tunable cryogenic microwave cavity
Authors: Potts C. A. , Davis J. P.
Published: July 2020

The ability to achieve strong-coupling has made cavity-magnon systems an exciting platform for the development of hybrid quantum systems and the investigation of fundamental problems in physics. Unfortunately, current experimental realizations are constrained to operate at a single frequency, defined by the geometry of the microwave cavity. In this article we realize a highly tunable, cryogenic, microwave cavity strongly coupled to magnetic spins. The cavity can be tuned in situ by up to 1.5 GHz, approximately 15% of its original 10 GHz resonance frequency. Moreover, this system remains within the strong-coupling regime at all frequencies with a cooperativity of ≈800.
Isaac Newton and the perils of the financial South Sea
Authors: Odlyzko Andrew
Published: July 2020

Despite Newton’s general brilliance and his expertise in finance, groupthink led him to plunge into the South Sea Bubble and lose much of his fortune.
Feral cat abundance, density and activity in tropical island rainforests
Authors: Lavery Tyrone H. , Alabai Masaafi , Holland Piokera , Qaqara Cornelius , Vatohi Nelson
Published: July 2020

Abstract ContextIntroduced predators, especially cats, are a major cause of extinction globally. Accordingly, an extensive body of literature has focussed on the ecology and management of feral cats in continental and island systems alike. However, geographic and climatic gaps remain, with few studies focusing on rainforests or tropical islands of the south-western Pacific. AimsWe aimed to estimate cat densities and elucidate activity patterns of cats and sympatric birds and mammals in tropical island rainforests. We hypothesised that cat activity would be most influenced by the activity of introduced rodents and ground-dwelling birds that are predominant prey on islands. MethodsWe used camera traps to detect feral cats, pigs, rodents and birds on four tropical islands in the south-western Pacific. We used spatial capture–recapture models to estimate the abundance and density of feral cats. Relative abundance indices, and temporal overlaps in activity were calculated for feral cats, pigs, rodents, and birds. We used a generalised linear model to test for the influence of pig, rodent, and bird abundance on feral cat abundance. Key resultsThe species most commonly detected by our camera traps was feral cat, with estimated densities between 0.31 and 2.65 individuals km−2. Pigs and introduced rodents were the second- and third-most commonly detected fauna respectively. Cat activity was bimodal, with peaks in the hours before dawn and after dusk. Cat abundance varied with site and the abundance of rodents. ConclusionsFeral cats are abundant in the tropical rainforests of our study islands, where one bird and two mammal species are now presumed extinct. Introduced rodents possibly amplify the abundance and impacts of feral cats at our sites. Peak cat activity following dusk did not clearly overlap with other species detected by our camera traps. We postulate cats may be partly focussed on hunting frogs during this period. ImplicationsCats are likely to be a major threat to the highly endemic fauna of our study region. Management of feral cats will benefit from further consideration of introduced prey such as rodents, and their role in hyperpredation. Island archipelagos offer suitable opportunities to experimentally test predator–prey dynamics involving feral cats.
Systematic review of equids and telemetry collars: implications for deployment and reporting
Authors: Hennig Jacob D. , Scasta J. Derek , Beck Jeffrey L. , Schoenecker Kathryn A. , King Sarah R. B.
Published: July 2020

Abstract
Data from animals equipped with global positioning system collars have advanced our understanding of vertebrates, but this technology has rarely been employed to study feral equids. Hesitation to equip feral equids with telemetry collars in the USA can often be attributed to safety concerns stemming from one study from the 1980s, where injuries were sustained by feral horses (Equus ferus caballus) equipped with radio-collars. Improvements in collar design over the ensuing quarter-century may have decreased risk of collar-related complications; however, telemetry-based studies on feral equids continue to be limited. In the present review, studies from wild and feral equids worldwide were systematically reviewed to better understand the mortality and injury risk in application of telemetry collars to equids. Our goals were to: (1) report the number of individual equids fitted with telemetry collars (1979–2017); and (2) document the number of individual equids that reportedly died or suffered injuries from collars or other sources. A comparative review of elk (Cervus canadensis), mule deer (Odocoileus hemionus) and pronghorn (Antilocapra americana) was also conducted to evaluate the relative risk of collar-related complications among equids and routinely collared North American ungulates. In total, 1089 wild and feral telemetered equids were identified across 48 studies. Of these, 87 (8.0%) were reported to have died, with only one (0.09%) mortality attributable to a collar. Comparatively, 23.0% (1095) of 4761 elk, mule deer and pronghorn fitted with telemetry collars were found to have died in the same number of studies, though no mortalities were reported to be related to the collar. Although wild and feral equids did not experience increased natural mortality compared with the other ungulates, studies have not provided sufficient information to assess relative risk of collar-related complications. Explicit reporting and discussion of telemetry collar impacts in future publications of all animal species are recommended, especially equids, to improve understanding of how telemetry collars can affect study individuals.
Nur77 controls tolerance induction, terminal differentiation, and effector functions in semi-invariant natural killer T cells
Authors: Kumar Amrendra , Hill Timothy M. , Gordy Laura E. , Suryadevara Naveenchandra , Wu Lan , Flyak Andrew I. , Bezbradica Jelena S. , Van Kaer Luc , Joyce Sebastian
Published: July 2020

Significance

Semi-invariant natural killer T (iNKT) cells are innate-like lymphocytes that control a variety of immune functions. iNKT cell functions are mediated by high-affinity interactions with self-agonists displayed by the lipid-presenting CD1d molecule. How iNKT cells attain tolerance to high-affinity interactions with self remains unknown. This understanding is of immunologic import, as an unbridled iNKT cell-mediated response can cause inflammatory diseases. We discovered that Nur77—a transcription factor expressed at high levels in iNKT cells—induced caspase-3–mediated apoptosis and markers of T cell exhaustion such as PD-1 in iNKT cell precursors, which led to hyporesponsiveness to a high-affinity lipid agonist. Thus, Nur77 plays a central role in self-tolerance induction of iNKT cells.
Transparency and language contact
Authors: Seguin Luisa
Published: July 2020

When communicating speakers map meaning onto form. It would thus seem obvious for languages to show a one-to-one correspondence between meaning and form, but this is often not the case. This perfect mapping, i.e. transparency, is indeed continuously violated in natural languages, giving rise to zero-to-one, one-to-many, and many-to-one opaque correspondences between meaning and form. However, transparency is a mutating feature, which can be influenced by language contact. In this scenario languages tend to evolve and lose some of their opaque features, becoming more transparent. This study investigates transparency in a very specific contact situation, namely that of a creole, Haitian Creole, and its sub- and superstrate languages, Fongbe and French, within the Functional Discourse Grammar framework. We predict Haitian Creole to be more transparent than French and Fongbe and investigate twenty opacity features, divided into four categories, namely Redundancy (one-to-many), Fusion (many-to-one), Discontinuity (one meaning is split in two or more forms,) and Form-based Form (forms with no semantic counterpart: zero-to-one). The results indeed prove our prediction to be borne out: Haitian Creole only presents five opacity features out of twenty, while French presents nineteen and Fongbe nine. Furthermore, the opacity features of Haitian Creole are also present in the other two languages.
Long-term effects of intensive instruction on fluency, comprehensibility and accentedness
Authors: French Leif M. , Gagné Nancy , Collins Laura
Published: July 2020

We assessed the long-term effects of intensive instruction on different aspects of L2 oral production. Adopting
the tridimensional model of oral production (Munro & Derwing, 1995a), we compared
high school learners who had received intensive ESL instruction (N = 42) with non-intensive learners
(N = 39) on perceptual measures of L2 fluency, comprehensibility, and accentedness 4 years after a 5-month
intensive instruction period. After controlling for academic ability and L2 proficiency, listeners’ ratings of fluency and
comprehensibility were significantly higher for the IG; however, there was no specific group advantage for accentedness,
suggesting both groups exhibited similar L2 accents. This study provides new empirical evidence that the oral fluency and
comprehensibility benefits of an intensive experience may be long lasting, even when learners’ subsequent classroom exposure to
the language is much more limited.
The effect of H2O on the vibrational populations of CO2 in a CO2/H2O microwave plasma: a kinetic modelling investigation
Authors: Verheyen C , Silva T , Guerra V , Bogaerts A
Published: July 2020

Plasma has been studied for several years to convert CO2 into value-added products. If CO2 could be converted in the presence of H2O as a cheap H-source for making syngas and oxygenates, it would mimic natural photosynthesis. However, CO2/H2O plasmas have not yet been extensively studied, not by experiments, and certainly not computationally. Therefore, we present here a kinetic modelling study to obtain a greater understanding of the vibrational kinetics of a CO2/H2O microwave plasma. For this purpose, we first created an electron impact cross section set for H2O, using a swarm-derived method. We added the new cross section set and CO2/H2O-related chemistry to a pure CO2 model. While it was expected that H2O addition mainly causes quenching of the CO2 asymmetric mode vibrational levels due to the additional CO2/H2O vibrational-translational relaxation, our model shows that the modifications in the vibrational kinetics are mainly induced by the strong electron dissociative attachment to H2O molecules, causing a reduction in electron density, and the corresponding changes in the input of energy into the CO2 vibrational levels by electron impact processes.
Optical imaging of antiferromagnetic domains in ultrathin CoO(001) films
Authors: Xu Jia , Chen Haoran , Zhou Chao , Shi Dong , Chen Gong , Wu Yizheng
Published: July 2020

Antiferromagnetic (AFM) domains in ultrathin CoO(001) films are imaged by a wide-field optical microscopy using magneto-optical birefringence effect. The magnetic origin of observed optical contrast is confirmed by the spin orientation manipulation through exchange coupling in Fe/CoO(001) bilayer. The finite size effect of ordering temperature for ultrathin single crystal CoO film is revealed by the thickness and temperature dependent measurement of birefringence contrast. The magneto-optical birefringence effect is found to strongly depend on the photon energy of incident light, and a surprising large polarization rotation angle up to 168.5 mdeg is obtained from a 4.6 nm CoO film with a blue light source, making it possible to further investigate the evolution of AFM domains in AFM ultrathin film under external field.
A review of edible insect industrialization: scales of production and implications for sustainability
Authors: Wade MacKenzie , Hoelle Jeffrey
Published: July 2020

Edible insects have emerged in the past decade as a sustainable alternative to agro-industrial production systems and livestock-based diets. Despite the expansion of the market and increases in academic publications, a review of the rapidly changing field of edible insect research has yet to be published. Here we present a comprehensive and systematic review of the research on edible insect industrialization, the mass rearing of insects for human consumption, published in the year 2018. Our review provides an overview of the edible insect industry, as the field becomes more industrialized, and research addresses health, safety, and other concerns of consumers and legislators. This review provides an understanding of the scales of edible insect industrialization from (a) the microbiological level of insect rearing, to (b) the external production factors within rearing facilities, (c) the development of insect products, (d) consumer acceptance of industrially reared insects, and (e) social and moral concerns with the industry. We contextualize reviewed works in relation to earlier and subsequent publications on edible insects, providing a view of the bigger picture as insect-based products are poised to become more widely available to global consumers. Overall, this review provides an overview of the edible insect industry for environmental researchers and policymakers interested in the linkages between food, agriculture, and climate change, as well as recent progress, remaining challenges, and trade-offs of an industry with potential to contribute to more sustainable diets.
Digital environment of vocational education in the Russian Federation
Authors: Beskrovnaya V , Fedorova O , Freidkina E
Published: July 2020

The article presents the formation of a digital educational environment for vocational education in the Russian Federation. Particular attention is paid to pedagogical approaches, the architecture of the digital educational environment, the experience of the St. Petersburg State University of Industrial Technologies and Design in the field of its use for training forest industry.
Issues of satellite images decoding in modern development of forest management
Authors: Galiullin I R , Glushko S G , Khamitova S M , Pestovskiy A S , Fedchenko E I , Ivanova M A
Published: July 2020

The processes of natural overgrowing of poorly used lands have led to the formation of a significant amount of unaccounted forest resources. As a result of a survey of the territory adjacent to the city of Kazan, we have identified numerous land plots that are uncontrollably overgrown with forests, an example of such a plot is given. Accounting for all areas covered by forest vegetation will significantly increase the forest cover of the Republic of Tatarstan. Using modern methods of “contour decoding” of satellite images allows us to identify almost all areas covered by forest vegetation, significantly increasing the efficiency of the use of forest resources. Using the methods of the so-called “taxation (estimated) decryption” of satellite images allows us to assess the features of the dynamics of modern forests. An assessment of the species composition and origin of forests using remote sensing methods, including based on the results of decoding satellite images, gives an idea of the distribution of derivative forests in the region. Forest inventory allows not only to keep a record of the forest fund, but also to assess the resources of forest biota in regional fragments of the biosphere, as well as identify the main trends in forest dynamics.
Mathematical methods for the evaluation of lands of forest fund
Authors: Kovyazin V , Kitcenko A
Published: July 2020

The article provides an overview of various methods for assessing the forest fund infrastructure during cadastral valuation, including a couple of possible methods of mathematical modeling, with the help of which it is possible to assess the impact of the forest fund infrastructure on the cadastral value, as well as the advantages and disadvantages of these methods.
Monitoring of Forest Land Cover Change in Binh Chau - Phuoc Buu Nature Reserve in Vietnam Using Remote Sensing Methods and GIS techniques
Authors: Kovyazin V F , Demidova P M , Lan Anh Dang Thi , Hung Dang Viet , Quyet Nguyen Van
Published: July 2020

Binh Chau - Phuoc Buu Nature Reserve is located in the tropical rainforest zone of southeast Vietnam. For monitoring purposes of forest land cover change in Reserve satellite images (Landsat 5, Landsat 7 and Sentinel-2A) taken in 1988, 2003 and 2019 were used. NDVI was used for the estimation of vegetation quality. Forest land cover were classified by 5 categories using maximum likelihood classifier algorithm in ENVI 5.3. After classification, differentiation of forest land cover was analysed on every image. The results confirm that the area of meadows and shrubs increased from 16.3% in 1988 to 19.1% in 2019, and conversely, the area of broad-leaved forests decreased from 80.7% to 77.3%. Thus, there is a general degradation of forest vegetation.
Problems and prospects of digitalization and informatization of forest education in Russia
Authors: Lobovikov M , Pryadilina N
Published: July 2020

Digital technologies are rapidly invading all spheres of life of modern society. Education is no exception. On the contrary, education is becoming one of the main subjects and beneficiaries of digitalization in the broad sense of the word, often in the most unexpected areas of knowledge obtaining, mastering and applying.
Results of application of 3D technologies for modelling the terrain of cutting areas in the North-Western Federal district of the Russian Federation
Authors: Svoykin F , Bazarov A , Soloviev A , Bazarova M , Bazarov F
Published: July 2020

The article discusses the use of 3D technologies for modeling the terrain of cutting areas in the North-Western Federal district of the Russian Federation. The technique of obtaining three-dimensional terrain maps, the translation of laid out maps into a vector format using Autodesk 3ds Max® software and the Terrain® tool is described. The preparation of the created 3D models for processing by a CNC milling machine using the ArtCam® software (ASCII STL text file format) is presented. The results of milling processing of the surface of the frame are presented.
The use of digital pedagogic in forest related higher education in Vietnam
Authors: Tereshchenko S , Thuy Tran Thi Thanh , Nga Tran Thi Thanh , Nha Nguyen Xuan
Published: July 2020

The article is devoted to the study of the application in practice of the digital pedagogic in the forest higher education in Vietnam. In the article, the problems of higher forest education development in Vietnam are considered. The problems associated with the organization of an effective training process for the forest sector specialists have been highlighted. The urgency of raising the qualification and competence of specialists of the forest industry by using innovative teaching methods in training is justified. Possibilities of the use of distance education technologies for the training of students and the improvement of professional skills of workers of the enterprises of the forest sector are considered.
Mobile learning in forestry education
Authors: Tereshchenko S , Zagorskaya M , Polyanskaya O , Bobritskaya Ju
Published: July 2020

In the article the experience of using mobile learning in forest education is considered. It examines the phenomenon of mobile pedagogy, mobile learning, describes structure of mobile teaching. The application of mobile pedagogy in learning in forest education is described. The attitude to the using of mobile pedagogic in forest high education of teachers and students is shown. Different mobile applications that can be used in the educational process are described. The experience of implementation of methods of mobile pedagogic in forest higher education in Saint-Petersburg State Forest Technical University is shown. The importance of using mobile pedagogic in nowadays education is stressed, because such innovational approaches may allow raising the students’ motivation for learning. Possibilities for the development of mobile pedagogic in forest high education are shown.
Using of digital methods for personnel training in Vietnamese forest sector
Authors: Tien Trinh Viet
Published: July 2020

The relevance of this article is due to the importance of forest resources for each state, since they play a special role in development from economic, environmental and social point of view. This statement is also relevant for Vietnam because forests of the country are rich in resources and preserve rich biological diversity. However, improper forest management leads to deforestation and forest cutting. The aim of the article is a theoretical justification for the need to improve the Vietnamese forest management system by training personnel using digital methods of education. The validity of the results and recommendations is ensured by the integrated application of general scientific methods, such as dialectical means of cognition, a systematic approach, structural and functional analysis methods, systematization and generalization, the principles of formal logic, the presentation of tabular material, etc. The result of the study is a suggestion to create a system of digital forest pedagogic for personnel training in forest management in Vietnam. The created system will allow minimizing the influence of the negative factors on the development of Vietnamese forest management. It is substantiated that many problems can be solved through training by using digital methods of education.