bluuebunny/crossref_metadata_2025 huggingface dataset:
A numerical study on the natural transition locations in the flat-plate boundary layers on superhydrophobic surfaces
Authors: Liu Bin , Zhang Yongming
Published: December 2020

In this paper, the natural transition locations in the flat-plate boundary layers on the superhydrophobic surfaces are studied by numerical methods. The laminar flow field in the whole stream-wise computational domain is obtained by solving the Blasius equation with the slip-velocity boundary condition on the wall. The boundary layer on the superhydrophobic surface becomes thinner than that on the ordinary surface. The linear instability analysis is performed on the laminar boundary layer, and the eN method is employed to predict the transition location. The two-dimensional (2D) Tollmien–Schlichting (T–S) waves are still more unstable than the three-dimensional (3D) ones on the superhydrophobic surfaces, so only the 2D waves are taken into consideration to predict transition. As the slip length becomes longer, the critical location of flow instability moves further downstream, and the unstable zone becomes smaller. Therefore, the superhydrophobic surfaces have the effect of delaying the natural transition and that the delay effect becomes stronger as the slip length becomes longer. The higher oncoming flow velocity leads to higher frequencies of the unstable T–S waves and the larger unstable zone. As the oncoming flow velocity rises, the transition location on the superhydrophobic surface moves once upstream and then downstream. Consequently, there is a “dangerous” oncoming flow velocity corresponding to the transition location, which is the closest to the lead edge. Furthermore, the transition delay effect of the superhydrophobic surface becomes stronger with the increase in the oncoming flow velocity.
The role of adhesion and binder stiffness in the impact sensitivity of cast composite energetic materials
Authors: Wickham J. A. , Beaudoin S. P. , Son S. F.
Published: December 2020

The drop weight impact or drop hammer test has been a staple of energetic material small-scale sensitivity testing for over 100 years, but the link between material properties and sensitivity has proven difficult to evaluate, especially for composite materials. In this study, the work of adhesion and elastic modulus of the binder were varied to assess their impact on the sensitivity of a family of plastic bonded explosive composite energetic materials. Drop weight impact tests performed using the German Bundesanstalt für Materialprufung impact test demonstrated significant decreases in sensitivity as the elastic modulus and the work of adhesion decrease. It was determined that the elastic modulus of the binder was the most significant contributor to the corresponding changes in sensitivity.
Heteroglossia in mother tongue instruction in Sweden and the development of plurilingual literacies
Authors: Reath Warren Anne
Published: December 2020

This article analyses how perceptions of and approaches to teaching linguistically heterogeneous groups in mother tongue instruction (MTI) in Sweden impact on the development of plurilingual literacies in that context. Linguistic ethnographic data collected over 12 months in classrooms and schools where MTI takes place were thematically categorized and data from the most prominent category, heterogeneity, were further coded into the heteroglossic categories of multidiscursivity and multivoicedness (Todorov 1984). The continua of biliteracy provides an additional interpretative framework. Results show that heteroglossic discursive practices involving diverse linguistic repertoires are commonly reported on and observed in MTI classrooms, and are viewed both as a resource for and an obstacle to learning. These results contribute to discussions on organizational and pedagogical approaches that work with rather than against heteroglossia, through resourceful use of languages to enhance learning in MTI and potentially other subjects as well.
A fixed point for black hole distributions
Authors: Gálvez Ghersi José T , Stein Leo C
Published: December 2020

Understanding distributions of black holes is crucial to both astrophysics and quantum gravity. Studying astrophysical population statistics has even been suggested as a channel to constrain black hole formation from the quantum vacuum. Here we propose a Gedankenexperiment to show that the non-linear properties of binary mergers (simulated with accurate surrogate models) generate an attractor in the space of distributions. Our results show that the joint distribution of spin magnitude and fractional mass loss evolves to a fixed point, converging in a few generations. The features of this fixed point distribution do not depend on the choice of the initial distributions in the range of mass ratios that we are able to probe. Since a black hole merger is irreversible it produces entropy—possibly the largest source of entropy in the Universe. The fixed-point distributions are neither isothermal nor isentropic, and initially thermodynamic states evolve away from thermality. We finally evaluate the specific entropy production rate per merger from initially thermal and non-thermal distributions, which converges to a constant.
Theory of polarization-averaged core-level molecular-frame photoelectron angular distributions: II. Extracting the x-ray-induced fragmentation dynamics of carbon monoxide dication from forward and backward intensities
Authors: Ota F , Hatada K , Sébilleau D , Ueda K , Yamazaki K
Published: December 2020

Recent developments in high-repetition-rate x-ray free electron lasers (XFELs) such as the European XFEL and the LSCS-II, combined with coincidence measurements using the COLTRIMS-reaction microscope, are now opening a door to realize the long-standing dream of creating molecular movies of photo-induced chemical reactions in gas-phase molecules. In this paper, we propose a new theoretical method to experimentally visualize the dissociation of diatomic molecules via time-resolved polarization-averaged molecular-frame photoelectron angular distribution (PA-MFPAD) measurements using the COLTRIMS-reaction microscope and the two-color XFEL pump–probe set-up. We used first- and second-order scattering theory within the muffin-tin approximation, which is valid for a sufficiently high kinetic energy of photoelectrons, typically above 100 eV, and for long bond lengths. This leads to a simple extended x-ray absorption fine structure (EXAFS)-type formula for the forward and backward scattering peaks in the PA-MFPAD structure. This formula relies only on three semi-empirical parameters obtainable from the time-resolved measurements. It can be used as a ‘bond length ruler’ on experimental results. The accuracy and applicability of the new ruler equation are numerically examined against the PA-MFPADs of CO2+ calculated with full-potential multiple scattering theory as a function of the C–O bond length reported in the preceding work (Ota et al J. Phys. B: At. Mol. Opt.). The bond lengths retrieved from the PA-MFPADs via our EXAFS-like formula coincide within an accuracy of 0.1 Å with the original C–O bond lengths used in the reference ab initio PA-MFPADs. We expect time-resolved PA-MFPADs to become a new attractive tool to make molecular movies visualizing intramolecular reactions.
Photon-excitation photon-emission maps (PhexPhem maps) with rovibronic resolution as a data base for theory and astrophysics part I: method and first results for H2
Authors: Schmidt Philipp , Knie Andre , Hans Andreas , Hosaka Kouichi , Ukai Masatoshi , Glass-Maujean Michele , Ehresmann Arno
Published: December 2020

Dispersed fluorescence of wavelengths between 75 and 180 nm has been recorded after excitation of room temperature

H

2

X

1

Σ

g

+

v
=
0

by narrow bandwidth monochromatized synchrotron radiation. Spectra have been taken in the exciting-photon energy range between 11 and 18 eV for discrete energy steps of 2.5 meV at a bandwidth of about 10 meV. The exciting-photon energy bandwidth has been narrow enough to induce transitions between individual rovibronic states. The resolution in the dispersed fluorescence detection was partly sufficient to resolve fluorescent transitions between individual rovibronic states. The recorded intensities are presented as two-dimensional photon-excitation photon-emission (PhexPhem) maps. They give a complete overview of experimental dispersed VUV/ FUV fluorescence spectra of H2 for these excitation energies, covering excitation from

H

2

X

1

Σ

g

+

v
=
0

to all known singly excited states. The presented proof of principle experiments show a way to generate spectroscopic reference data for theory benchmarking and the interpretation of astrophysical observations.
Anisotropic electronic and plasmonic properties of 2H-TiS2
Authors: Mazaherifar Mohsen , Elahi Mohammad , Pourfath Mahdi
Published: December 2020

Plasmon characteristics in a monolayer of 2H-TiS2 in the presence of strain are carefully analyzed by employing the density functional theory along with random phase approximation. The anisotropic properties of 2H-TiS2 are carefully analyzed under biaxial strains. An anisotropic semi-Dirac cone in the electronic band-structure is observed at a specific biaxial strain configuration. This unique characteristic can be explained by the hybridization of orbitals at the conduction band minimum and valence band maximum which can be effectively tuned by applying strain. The effect of anisotropic electronic band-structure on the properties of plasmons is investigated by utilizing the electron energy loss spectrum analysis. A

q

dispersion along the Γ−K direction and a linear dispersion along the

Γ
−

M

′

were found. The linear dispersion characterizes an extrinsic acoustic plasmon mode that can be tuned by the carrier concentration.
Superconductivity in the three-band model of cuprates: nodal direction characteristics and influence of intersite interactions
Authors: Zegrodnik M , Biborski A , Fidrysiak M , Spałek J
Published: December 2020

The three-band Emery model is applied to study the selected principal features of the d-wave superconducting phase in the copper-based compounds. The electron–electron correlations are taken into account by the use of the diagrammatic expansion of the Guztwiller wave function (DE-GWF method). The nodal Fermi velocity, Fermi momentum, and effective mass are all determined in the paired state and show relatively good agreement with the available experimental data, as well as with the corresponding single-band calculations. Additionally, the influence of the next-nearest neighbor oxygen–oxygen hopping and intersite Coulomb repulsion terms on the superconducting phase is analyzed.
A four-terminal-pair Josephson impedance bridge combined with a graphene-quantized Hall resistance
Authors: Bauer S , Behr R , Elmquist R E , Götz M , Herick J , Kieler O , Kruskopf M , Lee J , Palafox L , Pimsut Y , Schurr J
Published: December 2020

This paper introduces a four-terminal-pair impedance bridge based on pulse-driven Josephson junctions arrays which is designed to link any kind of impedance to the quantized Hall resistance. The unique features of the quantized Hall resistance in a multiple series connection allows to dispense a combining network and leads to a compact and simple design of the whole setup. Moreover, the low noise of a quantized Hall resistance reduces the measurement time compared to resistance standards at room temperature which is essential for the characterization of quantum Hall devices in the AC regime. A first measurement campaign confirmed the expected low noise of 1.82 

n
V

/

H
z

for a link to a 10 nF capacitance standard. The repeatability of the bridge was found to be few parts in 108. Capacitance and resistance standards were measured at 1233.15 Hz against graphene based quantum Hall resistance devices.
Determination of the real quantum yield of the heterogeneous photocatalytic H2 production reaction and insights
Authors: Jing Dengwei , Luo Bing , Liu Huan , Guo Liejin
Published: December 2020

Determination of the real quantum yield (QY) of a heterogeneous photocatalytic H2 production reaction is crucial and challenging. Here, we constructed a setup enabling the exact measurement of the number of incident photons received by photo-vessel, and the directly absorbed part by photocatalysts, thus achieving simultaneous determination of QY and apparent quantum yield (AQY). It turns out that over the whole investigated wavelength region, the value of AQY is significantly smaller than that of QY. For instance, the AQY and QY of Cd0.5Zn0.5S were measured as 40% and 70% at 420 nm, respectively. We have demonstrated that a lot of incident photons are scattered by the photocatalyst particles and dissipated, instead of being absorbed and converted. It indicates that the true photocatalytic performance of a photocatalyst could have been severely underestimated in the past by AQY in previous studies. Therefore, our work should be valuable for accurate catalytic efficiency evaluation of a photocatalyst, and contributes to the rapid development of the technology.
Low-temperature plasma polymerized fluorocarbon coating promotes surface charge dissipation in polystyrene
Authors: Zhang Penghao , Zhang Cheng , Zhang Chuansheng , Kong Fei , Yan Ping , Shao Tao
Published: December 2020

Polystyrene (PS) is a common insulating material in pulsed power devices, which has excellent and reliable insulation properties. However, the charge accumulation on the insulator surface seriously threatens its surface insulation property. Surface modification has been verified as an effective way for inhibiting surface charge accumulation. In this paper, plasma polymerized fluorocarbon (PPFC) coating was prepared by low-temperature plasma polymerization in the mixture of methyl-methacrylate and dodecafluoroheptyl-methacrylate (DFHMA). Compared with the untreated PS, the surface charge dissipation rate of PPFC coating is increased by more than 6 times. The introduction of DFHMA makes the coating have no obvious ageing effect after the storage, and has good reusability after the surface flashover. This work provides a new method for modification of polymer dielectrics and a novel way for the preparation of high-charge-dissipation polymers in other related fields.
Many-particle induced band renormalization processes in few- and mono-layer MoS2
Authors: Yue Yuan-Yuan , Wang Zhuo , Wang Lei , Wang Hai-Yu , Chen Yang , Wang Dan , Chen Qi-Dai , Gao Bing-Rong , Wee Andrew T S , Qiu Cheng-Wei , Sun Hong-Bo
Published: December 2020

Band renormalization effects play a significant role for two-dimensional (2D) materials in designing a device structure and customizing their optoelectronic performance. However, the intrinsic physical mechanism about the influence of these effects cannot be revealed by general steady-state studies. Here, band renormalization effects in organic superacid treated monolayer MoS2, untreated monolayer MoS2 and few-layer MoS2 are quantitatively analyzed by using broadband femtosecond transient absorption spectroscopy. In comparison with the untreated monolayer, organic superacid treated monolayer MoS2 maintains a direct bandgap structure with two thirds of carriers populated at K valley, even when the initial exciton density is as high as 2.05 × 1014 cm−2 (under 400 nm excitations). While for untreated monolayer and few-layer MoS2, many-particle induced band renormalizations lead to a stronger imbalance for the carrier population between K and Q valleys in k space, and the former experiences a direct-to-indirect bandgap transition when the initial exciton density exceeds 5.0 × 1013 cm−2 (under 400 nm excitations). Those many-particle induced band renormalization processes further suggest a band-structure-controlling method in practical 2D devices.
A framework for automated time-resolved analysis of cell colony growth after irradiation
Authors: Koch Robin A , Harmel Christoph , Alber Markus , Bahn Emanuel
Published: December 2020

Understanding dose-dependent survival of irradiated cells is a pivotal goal in radiotherapy and radiobiology. To this end, the clonogenic assay is the standard in vitro method, classifying colonies into either clonogenic or non-clonogenic based on a size threshold at a fixed time. Here we developed a methodological framework for the automated analysis of time course live-cell image data to examine in detail the growth dynamics of large numbers of colonies that occur during such an experiment. We developed a segmentation procedure that exploits the characteristic composition of phase-contrast images to identify individual colonies. Colony tracking allowed us to characterize colony growth dynamics as a function of dose by extracting essential information: (a) colony size distributions across time; (b) fractions of differential growth behavior; and (c) distributions of colony growth rates across all tested doses. We analyzed three data sets from two cell lines (H3122 and RENCA) and made consistent observations in line with already published results: (i) colony growth rates are normally distributed with a large variance; (ii) with increasing dose, the fraction of exponentially growing colonies decreases, whereas the fraction of delayed abortive colonies increases; as a novel finding, we observed that (iii) mean exponential growth rates decrease linearly with increasing dose across the tested range (0–10 Gy). The presented method is a powerful tool to examine live colony growth on a large scale and will help to deepen our understanding of the dynamic, stochastic processes underlying the radiation response in vitro.
Simultaneous needle catheter selection and dwell time optimization for preplanning of high-dose-rate brachytherapy of prostate cancer
Authors: Wang Chao , Gonzalez Yesenia , Shen Chenyang , Hrycushko Brian , Jia Xun
Published: December 2020

Purpose. Needle catheter positions critically affect the quality of treatment plans in prostate cancer high-dose-rate (HDR) brachytherapy. The current standard needle positioning approach is based on human intuition, which cannot guarantee a high-quality plan. This study proposed a method to simultaneously select needle catheter positions and determine dwell time for preplanning of HDR brachytherapy of prostate cancer. Methods. We formulated the needle catheter selection problem and inverse dwell time optimization problem in a unified framework. In addition to the dose objectives of the planning target volume (PTV) and organs at risk (OARs), the objective function incorporated a group-sparsity term with a needle-specific adaptive weighting scheme to generate high-quality plans with the minimal number of needle catheters. The optimization problem was solved by a fast-iterative shrinkage-thresholding algorithm. For validation purposes, we tested the proposed algorithm on 10 patient cases previously treated at our institution and compared the resulting plans with plans generated using needle catheters selected manually. Results. Compared to the plan with manually selected needle catheters, when normalizing both plans to the same PTV coverage V
100% = 95%, the plans generated by the proposed algorithm reduced median V
125% from 65% to 64%, but increased median V
150% from 35% to 38%, and V
200% from 14% to 16%. All planning objectives were met. All clinically important dosimetric parameters of OARs were reduced. D
1cc of bladder and rectum were reduced from 8.57 Gy to 8.50 Gy and from 7.24 Gy to 6.80 Gy, respectively. D
max of urethra was reduced from 15.85 Gy to 15.77 Gy. The median number of selected needle catheters was reduced by two. The computational time for solving the proposed optimization problem was ∼90 s using MATLAB. Conclusion. The proposed algorithm was able to generate plans for prostate cancer HDR brachytherapy preplanning with increased median conformity index (0.73–0.77) and slightly lower median homogeneity index (0.64–0.62) with the number of selected needles reduced by two compared to the manual needle selection approach.
A method using 4D dose accumulation to quantify the interplay effect in lung stereotactic body radiation therapy
Authors: Huesa-Berral Carlos , Burguete Javier , Moreno-Jiménez Marta , Diego Azcona Juan
Published: December 2020

The purpose of this study was to devise and evaluate a method to quantify the dosimetric uncertainty produced by the interplay between the movement of multileaf collimator and respiratory motion in lung stereotactic body radiation therapy. The method calculates the dose distribution for all control points from a dynamic treatment in all respiratory phases. The methodology includes some characteristics of a patient’s irregular breathing patterns. It selects, for each control point, the phases with maximum and minimum mean dose over the tumor and their corresponding adjacent phases, whenever necessary. According to this selection, the dose matrices from each control point are summed up to obtain two dose distributions in each phase, which are accumulated in the reference phase subsequently by deformable image registration (DIR). D
95 and

D

min
,
0.035
cc

were calculated over those accumulated dose distributions for Gross Tumor Volume (GTV), Planning Target Volume—based on Internal Target Volume approach—and Evaluation Target Volume (ETV), a novel concept that applies to 4D dose accumulation. With the ETV, DIR and interplay uncertainties are separated. The methodology also evaluated how variations in the breathing rate and field size affects the mean dose received by the GTV. The method was applied retrospectively in five patients treated with intensity modulated radiotherapy—minimum area defined by the leaves configuration at any control point was at least 4 cm2. Uncertainties in tumor coverage were small (in most patients, changes on D
95 and

D

min
,
0.035
cc

were below 2% for GTV and ETV) but significant over- and under-dosages near ETV, which can be accentuated by highly irregular breathing. Uncertainties in mean dose for GTV tended to decrease exponentially with increasing field size and were reduced by an increase of breathing rate. The implementation of this method would be helpful to assess treatment quality in patients with irregular breathing. Furthermore, it could be used to study interplay uncertainties when small field sizes are used.
Principles and impacts of dynamic threshold voltage in a p-GaN gate high-electron-mobility transistor
Authors: Wei Jin , Xu Han , Xie Ruiliang , Chen Kevin J
Published: December 2020

GaN power transistors are attracting increasing attention for next-generation power switching applications. However, GaN power transistors should not be regarded as a direct replacement for silicon power metal–oxide–semiconductor field-effect transistors, since the unique properties of GaN power transistors require special treatment. In this work we review a unique and critical property of GaN power transistors, the dynamic threshold voltage (V
th). GaN power transistors feature a p-GaN gate structure, while the gate metal contacts the p-GaN layer through a Schottky junction. This unique p-GaN gate structure is distinctively different from the silicon metal–oxide–semiconductor gate structure in that the p-GaN layer is actually a floating region without direct electrical contact to the external electrodes of the device. The floating p-GaN layer enables a charge storage process during the switching operation of a p-GaN gate high-electron-mobility transistor. Through carefully designed experiments, the strong correlation between charge storage and the dynamic V
th shift has been revealed; this also serves as an approach to accurately predict the dynamic V
th during switching operation. The influence of the dynamic V
th on power switching applications is discussed. For example, with a positive dynamic V
th shift, the reverse conduction voltage of a GaN power transistor is significantly increased, adding to the power loss. This positive V
th shift also demands a sufficiently high gate drive voltage to ensure that the GaN power transistor can be fully turned on, which reduces the safety margin for the gate reliability of the device. To design a GaN based power switching circuit, accurate simulation of the device/circuit characteristics is necessary. Circuit simulations that do not consider the dynamic V
th lead to a large deviation from the measurement circuit characteristics. We demonstrate that by incorporating the dynamic V
th into the circuit model this deviation can be effectively eliminated.
Programmable self-foldable films for origami-based manufacturing
Authors: George Derosh , Madou Marc J , Peraza Hernandez Edwin A
Published: December 2020

Manufacturing of three-dimensional structures of millimeter and sub-millimeter sizes is required in emerging applications in microelectronics, packaging, and particle entrapment. This paper presents a manufacturing method for three-dimensional polyhedral structures at such scales enabled by programmable, self-foldable polymer films. The manufacturing method starts with a three-dimensional target shape and uses origami design to generate the outline and fold pattern of a planar film that can be folded towards the target shape. Double-exposure photolithography is employed to pattern a polymer film based on the generated geometry along with stiff faces of high crosslinking density and flexible folds of low crosslinking density. During the development step of the photolithography process, the folds absorb the developer solution from one side, creating a concentration gradient across their thickness. The non-uniformly absorbed developer in the folds is evaporated when the film is heated, causing non-uniform strains across their thickness and enabling self-folding. It is experimentally determined that the fold angles exhibited by the folds are directly proportional to the ratio between their width along the folding direction and the film thickness, which enables programming of the folding response through modulation of the fold dimensions. Different structures are fabricated to demonstrate the effectiveness of the developed manufacturing method.
Failure analysis of self-healing epoxy resins using microencapsulated 5E2N and carbon nanotubes
Authors: Zamal Hasna Hena , Barba David , Aïssa Brahim , Haddad Emile , Rosei Federico
Published: December 2020

Investigation on self-healing properties of epoxy containing microcapsules of pure 5-ethylidene-2-norbornene (5E2N) and mixed multi-walled carbon nanotube (MWCNT) suspension is presented in this work using lap shear and mode I fracture tests. While both systems show significant self-healing functionalities between 39% and 97%, those repaired with MWCNT/5E2N microcapsules are found to have mechanical recovery efficiencies two times higher than those containing 5E2N alone, under different types of loading. MWCNT/5E2N microcapsules are also found to improve the physical strength of the epoxy matrix much higher than microcapsules containing only 5E2N. Compared to self-healing epoxy systems made of 5E2N microvessels, the dispersion of 0.10 wt.% of only MWCNTs inside the encapsulated monomer increases the lap shear strengths of the pristine materials and the self-healing materials tested after one fracture/curing cycle, by about 50% and 250%, respectively. Using fractographic observations, Raman spectroscopy and scanning electron microscopy, we observe the occurrence of a ring opening metathesis polymerization reaction and the contribution of MWCNTs to strengthening the material. The present work indicates that the MWCNT/5E2N microcapsule when incorporated into an appropriate epoxy formulation can serve as efficient self-healing matrix material for laminated composites, as well as self-healing structural adhesives for composite bonded joints, two features that make this system highly relevant for applications in aerospace engineering.
Hybridized nanofluid with stagnation point past a rotating disk
Authors: Ahmad Shafiq , Nadeem Sohail
Published: December 2020

Hybrid nanofluid is a mixture of two different nanoparticles that offer better heat transfer performance and thermophysical properties than traditional heat transfer fluids (water, oil, and refrigerant-134A) and nanofluid with single nanoparticles. Here, a type of hybrid nanofluid containing single-wall carbon nanotubes (SWCNTs) and multi-wall carbon nanotubes (MWCNTs) nano-sized particles with water and refrigerant-134A as base fluid is analytically modeled to establish the problem of the steady laminar MHD stagnation-point flow of a SWCNT–MWCNT/water-refrigerant-134A hybrid nanofluid through a rotating disk. Further, the influence of partial slip, viscous dissipation, and thermal slip are examined. Variables of von Karman are being used to transform partial differential equations in ordinary differential equations, which are solved numerically applying boundary value problem solver (bvp4c) in the MATLAB software. A comparison table for specific cases is provided to see the accuracy of our numerical results with recent data. The velocity and temperature behavior are plotted for various parameters. It is perceived that the fluid temperature is higher for hybrid nanofluid as compared to simple nanofluid and reverse behavior is observed for radial velocity. Further, the azimuthal velocity diminishes with the increasing value of magnetic and velocity slip parameters.
CuO nanoparticles effects on poplar×aspen hybrid clones at various stages of microclonal propagation
Authors: Zakharova O , Kolesnikova E , Kolesnikov E , Yevtushenko N , Morkovin V , Gusev A
Published: December 2020

We have studied the effects of CuO nanoparticles with the mean lateral dimension 300×500 nm and thickness about 50 nm on hybrid poplar×aspen clones at various stages of micropropagation. It has been established that CuO nanoparticles display a strong sterilizing activity and enhance rhizogenesis in microplants. At the culture establishment stage exposure to 1.5 - 3 μg/L CuO increased the number of leaves and roots, and stimulated the root system development. At 15 μg/L had an inhibiting effect on the studied parameters. At the multiplication stage we observed a considerable decrease in the height of shoots, and thickness of leaf lamina and stem diameter. At the same time a significant increase in the regenerants survival rate was observed (+20%), together with improved rhizogenesis. During the rooting stage, a 30% increase in the number of microclones with roots was detected, as well as a twofold increase in the number of roots on each plant. Besides, the nanomaterial had a stimulating effect on the shoots growth, increasing their height by 25%.Thus, it has been established that CuO nanoparticles produce differently directed effects on the growth and development of poplar×aspen hybrid microclones, depending on the micropropagation stage.
Survival rate of the Crimean pine forest cultures (Pinus pallasiana D. Don) created by non-standard seedlings on Don hilly sands
Authors: Turchina T A , Bannikova O A
Published: December 2020

Experimental forest cultivations of Crimean pine were produced on cohesive-sandy soils with hilly terrain to show the possibility of using non-standard seedlings. The minimum height of the seedlings was 10 cm (a standard indicator) compared to 2.0…2.9 cm – the stem diameter at the root collar (a non-standard indicator). In an experiment the agronomic technique of preplant treatment of the seedlings’ root systems with a solution of Kornevin (a biostimulant, Agrosintez, Russia) was used. When creating forest cultures by hand planting, the differences between the experimental options in terms of the survival rate and the nature of variation depending on the quality of the seedlings used were not significant (actual Student’s and Fisher’s coefficients is less than tabular). Treatment of root systems with Kornevin solution contributed to a more even distribution of the plants in the area. Mechanized planting did not provide for a high survival rate of forest cultures (the rate was 58.4% in the 1st year and 37.3% in the 3rd year), while the surviving plants did not form a homogeneous population (variation factor 30.5…71.0). The results indicated that it was possible to use seedlings of non-standard sizes in renewal after treating root systems with solutions of root stimulants.
Modeling of light propagation in a wood polymer-sand composite
Authors: Storodubtseva T , Bondarev B , Sadrtdinov A
Published: December 2020

The subject of the research is wood polymer-sand composite (WPSC) and study of its physical and mechanical properties. In this case it is propagation of light in the material using simulation and development of a computer program to simulate the propagation of UV radiation in WPSC block. A separate computer program in the Object Pascal language was compiled to study the model. The program is designed to simulate two-dimensional approximation of infrared, visible, ultraviolet radiation propagation in wood polymer-sand composite. The program is applicable in a wide range of concentrations of the composite components, for different optical absorption coefficients of the components, depending on the wavelength of the radiation. Concentrations, optical properties of the components, and lighting conditions can be specified in the text of the program. The results of the program are the structure of the composite as a random uniform distribution of wood and sand fragments in a polymer matrix, a cartogram and a graph of the intensity distribution in the composite specimen. The result has been obtained: penetration depth of destructive UV radiation is about 1.5 mm at an optimal concentration of the components CW=45%, CPI=35%, CSa = 20%.
Theoretical research of the work of technological equipment for lifting large planting material with a soil clod
Authors: Drapalyuk M V , Druchinin D Yu , Pozdnyakov E V
Published: December 2020

Large woody plants are a promising type of planting material for use in landscaping and forestry. The most labor-intensive technological operation in the process of growing them is lifting. To increase efficiency, this type of work must be performed using special equipment. The aim of the study is to study the process of plantlets lifting with a soil clod based on mathematical modeling methods to determine the optimal design parameters of lifting equipment developed by the authors. For a theoretical study of the equipment working process, a mathematical description of the interaction of the digging working tool with the soil-plant environment is carried out. The research work with the model consisted in the implementation of computer experiments to solve the compiled differential equation of the working tool motion around a fixed axis. Moreover, within the framework of changing the parameters of the working tool and the medium being processed, the dependences of the moments created by the driving forces and resistance forces are recorded. According to the results of the study, patterns of changes in the power characteristics of the digging process were established depending on the parameters of the working tool and the soil-plant environment.
Analysis of the information content of tenders for the removal of unwanted vegetation
Authors: Ersson B T , Platonov A , Zimarin S
Published: December 2020

To ensure the safe functioning of transport infrastructure facilities on their territory a set of works is carried out to remove unwanted trees and shrubs. The aim of the study is the formation of objective information about the most popular technological operations during the performance of these works and the development of recommendations on its basis for production. The methodological basis of our research was a complex of methods of logical, statistical and comparative analysis. Researchers analyzed more than 8,100 competitive bids for the removal of unwanted vegetation, according to a number of criteria. It was revealed that in 18.8% of the competitive bids, the technical task was completely absent, in 40.8% there was no mention of the necessary machines / mechanisms, in 66.4% there was no information about the necessary technological process for influencing unwanted vegetation, while the minimum 30% of the work involves only a manual way to remove it. The analysis of the distribution of the names of works by the relative demand coefficient is carried out, the expediency of reducing their nomenclature is established. The results of the work can be used by manufacturing enterprises engaged in the maintenance and operation of transport infrastructure facilities.
Reduction of dynamic loads on the hydraulic drive of forest boom lifter
Authors: Glushkov S , Popikov P , Chetverikova I , Druchinin D
Published: December 2020

The article is devoted to the reduction of dynamic loads on hydraulic drive by optimization of hydraulic cylinder for boom lifting and parameters of new damping device. A mathematical model of the working process of the boom lifting mechanism of serial hydraulic manipulator LV-184A has been solved. The optimal position of the hydraulic cylinder, in which the fluid pressure is reduced from 12.4 MPa to 11.3 MPa, has been found. It takes into account the forces of inertia and compliance of hydraulic drive. Connecting a new damper reduces the maximum pressure in the piston cavity of the hydraulic cylinder by 47%. The minimum of maximum values of the working fluid pressure is achieved when the damper throttle channel diameters are in the range of 4.0–4.5 mm. The aim (reduction of dynamic loads) is achieved by optimizing the configuration of the boom lift cylinders and the parameters of new damper. It significantly increases reliability of hydraulic drive elements and efficiency of manipulator-type machines in forestry complex.
Condition assessment of species of the genus Pseudotsuga Carr in Voronezh in order to predict seed productivity in the urban environment
Authors: Chekmeneva Yu V , Dorofeeva V D
Published: December 2020

In the conditions of the Central Black Earth region, in the park plantations of the city of Voronezh, the categories of tree conditions and seed productivity of the genus Pseudotsuga Carr were compared. Estimated yield, linear parameters of cones and seeds. The average values and the amplitude of the variability of the morphometric parameters of cones and seeds are determined. It was shown that in urban conditions at different objects the variability of attributes increases and the category of condition worsens for trees that grow in close proximity to roads, and are also in a depressed state due to shadowing by neighboring trees. The possibility of phenotypic selection of trees for stability in an urban environment by the level of variability of the parameters of the generative sphere is considered. It was revealed that variability at the level of cultivated phytocenoses is weakly expressed than that of individual trees at the endogenous level. In this regard, selection requires a more in-depth study of the polymorphism of cones and seeds to identify correlative traits associated with tree productivity indices.
Heavy metals in soils under various tree species
Authors: Kramareva T N , Gorbunova N S , Tikhonova E N , Gromovik A I
Published: December 2020

The issues of mutual influence of forest and soil attract the attention of researchers not only in theory, but also in practice, especially in the forest-steppe and steppe regions of the country. The researchers drew attention to the rapid changes in soil properties associated with forest planting. In addition, the composition and properties of soils are affected by the rock composition of forest belts. The main chemical, physical, and physical-chemical properties of ordinary chernozems under forest stands, of different rock composition, were studied. The same indicators were investigated in the chernozems occupied by arable land. It is shown that protective forest strips do not significantly affect the physical properties of soils. Chemical and physical-chemical properties change under the influence of wood crops. The gross content and mobile compounds of heavy metals in chernozems occupied by tree species were studied. It is shown that various HM and their compounds have their own characteristics of content and intra-profile distribution. The content and distribution of heavy metals is determined by the pH value, the content and distribution of silty particles, and humus (Corg). In addition, the nature of vegetation and various types of wood species have a significant impact on the content and profile distribution of heavy metals.
Post-fire successions in protected mountain forests of Crimea
Authors: Levchenko K , Matveev S , Konstantinov A
Published: December 2020

Forest fires are one of the most powerful factors, not only in Russia, but all over the world. It affects the structure of ecosystems and causes the landscape transformations in it. In Crimea, the ‘Krymskiy’ National Park, where research was conducted, is a major keeper of population natural forests. Post-pyrogenic changes in vegetation cover were studied in pine phytocenoses (Pinus sylvestris L., Pinus pallasiana D. Don.) and juniper phytocenoses (Juniperus communis subsp. hemisphaerica C. Presl., Juniperus sabina L.). The investigated areas were covered by fire different intensivity 2-37 years ago. It was found that the surface fires damages all elements of the forest phytocenosis. The juniper forests burn down completely and have not recovered in a period of up to 20 years. Forest fires cause secondary post-fire (pyrogenic) regressive succession in the mountain forests of Crimea. Herbaceous plants appear on the investigated sample areas where the forest is burnt: violent competitor plants (K-plants); stress-resistant plants (C-plants) and ruderal plants (P-plants), as well as – plants-pyrophytes. In the first years after a forest fire, the herbaceous plant community is more diverse and aligned. In subsequent years, the number of species decreases, and the index alpha plant diversity value also decreases.
Change of Quercus robur L. acorns seedlings cytogenetic parameters under anthropogenic impact
Authors: Popova A , Popova V
Published: December 2020

Long-term dynamic of cytogenetic parameters of the seedlings apical root meristem was analyzed for the Quercus robur for Central Black-Soil region. Central Black-Soil region located in the European part of Russia (geographical coordinates for Voronezh city: 51.660781; 39.200269) in the temperate climate zone. Annual climate indicators were analyzed to determine the possible influence of precipitation amount and temperature fluctuations during pollination and seed formation in the parent trees. Seed progeny cytogenetic parameters of trees growing in urban and suburban conditions were characterized by an increase in mitotic activity and the proportion of cells with mitotic pathologies, the appearance of micronucleus and residual nucleoli in mitosis. There was possible consequence of the complex technosphere negative factors impact on populations. The mitotic index for urban populations (from 6.8% to 9.5 %) was approximately at the same level for all years in long-term dynamics. There was a sharp decrease in mitotic activity (4.6 %) for the control area in 2019 compared with the data for 2008 (10.5%). The proportion of cells with mitosis pathologies in the meristems of urban seedlings was increased. There was a significant prophase-cells proportion increase among the seedlings. The reduction of number of pathologies may indicate the check-point repair system operation.
Mechanism of destruction of Quercus robur and Betula pendula leaves by exposure of organic pollutants
Authors: Belchinskaya L , Khodosova N , Novikova L , Marcomini A , Zhuzhukin K
Published: December 2020

Exposure of industrial pollutants including styrene, formaldehyde, acetone in the concentration range of maximal permissible concentration of working zone on leaves of silver birch (Betula pendula) and English oak (Quercus robur) chosen as model objects were studied and a mechanism of degradation was proposed. At a macroscopic level an indicator role of the leaf pattern for industrial organic pollutants with various functional groups was established. The differentiated effect of biotoxicants revealed selectivity of chemical reactions and appearance of various products of these reactions on the surfaces of the leaf blade. For all studied objects, systemic IR spectroscopic studies of cuts from oak and birch leaves were carried out. The characteristic frequencies testifying to interaction of pollutants with leaf tissue have been identified. The criteria for the control of tree plantations have been proposed, manifesting in a combination of two methods: at the macroscopic level, by establishing the indicator role of the pattern, and at the molecular level, by IR spectroscopic determination of chemical interaction in the system "functional groups of biotoxicants - leaf blade". The studies carried out make it possible to create a database of industrial pollutants and propose interrelated criteria for monitoring tree plantations.
Use of fuses of increased accuracy in the drives of rotary forestry machines
Authors: Zelikov V A , Raghuram Kadali B , Stasyuk V V , Kazachek M N
Published: December 2020

The review of the most common fuses to limit the torque used on rotary forestry machines used in difficult conditions, including felling, is performed. A review of the designs of the most common fuses on these machines for limiting the torque: pin, cam and friction is carried out. Both the advantages and disadvantages of these fuses are considered. The necessity of using more advanced fuses for torque limitation on rotary forestry machines with a firing accuracy factor less than that of the standard torque fuses currently used is identified. It is proposed to use fuses with increased accuracy of operation with inclined grooves and pins on rotary forestry machines. The design of a promising fuse for limiting torque using inclined grooves and pins is considered. The technique of an experiment to study the accuracy factor of the fuse at a specially designed stand is presented. The results of experiments to identify the dependence of the accuracy factor on the angle of the groove of the fuse. Further ways are suggested for improving the design of a fuse with increased accuracy of operation with inclined grooves and pins.
Assessment of the regional tax potential and its role in the formation of the budget system of the Russian Federation
Authors: Tsapulina F , Makushev A , Ergunova O , Arlanova O , Lvova M , Matveeva O
Published: December 2020

In this work, a study of tax revenues to the budgets of the Russian constituent entities for the fulfillment of state obligations by the Russian regions is carried out. The assessment of the regional tax potential as a key indicator of budgetary provision is determined on the example of the subject of the Russian Federation – Chuvash Republic – using the methodology of correlation and regression analysis. As a result, to improve the optimality of the regional tax policy in terms of current and forecast planning of tax payments to the budget of the Chuvash Republic, it is established which factors have a greater impact on the amount of tax revenues of a given constituent entity of the Russian Federation, and which to a lesser extent. It seems appropriate to use the author’s model for calculating tax revenues to the budget of the Chuvash Republic as an example of budgeting for other Russian entities. The process of modeling the tax potential of a region is indicated not only by an assessment of its current state, but also as part of project management for forecasting tax policies and tax reserves. The practical application of the tax potential with the available information base and regional government’s own instruments argues for the effectiveness of the fiscal policy of the Russian Federation, which is aimed at implementing tax regulation of economic processes while improving the quality of life of the population of Russia.