bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling the movement of slurry in the channel of a nature-like pump used for the safety laying of the worked out space
Authors: Vasilyeva M A , Yusupov G A , Nagornov D O , Puskarev A E
Published: January 2021

The most important task of the production of the mineral raw materials industry is to increase the efficiency of the equipment and infrastructure in operation. In particular, this also applies to the need to create transport systems with high productivity while reducing the cost of transporting mineral raw materials and waste from its processing. Particular attention is paid to the use of hydraulic filling systems as a measure to prevent man-made tectonic earthquakes during prolonged and continuous development of deposits. In this paper, we consider the problem aimed at solving the fundamental problems of developing effective methods for controlling the flow of pasty substances in pipelines of variable cross-section, intended for the production of pumping equipment and used in such industries as mining, chemical, food, etc.
Improving the competitiveness of Russian industry in the production of measuring and analytical equipment
Authors: Repinskiy O D , Konyukhov V Yu , Bovkun A S , Schupletsov A F
Published: January 2021

The creation of a high-tech competitive industry in the production of measuring and analytical equipment in Russia in a highly competitive environment is impossible without the development and implementation of innovative products. The vast majority of Russian enterprises invest their funds in the purchase of imported innovations instead of investing in creation of their own R & d/D (Research, Development and Engineering). Such path of development of Russian enterprises is seems / seems to be a dead end. One can observe a growing trend in the share of R & d/D expenditures on the global market. Nowadays the leading countries of the world industry such as the United States, China, Japan and Germany invest much bigger than over countries/invest in science more than over countries. Large-scale development and innovation implementation can be realised under creation of the system based on interconnected elements “industry-innovation-science-education”. Expansion and intensification of fundamental and applied research, improvement quality of teaching mathematics, physics and engineering disciplines in higher and secondary educational institutions are seemed to be necessary/seem to lead to better results. Large industrial Russian companies, leaders in certain sectors of industry with a powerful modern production infrastructure and huge financial capacity should act as a driving motive of the mentioned system. The state should provide support by means of legislative activity aimed to create an industrial and innovation policy providing production of innovative items which will be able to compete in high-tech segments of the world market.
Numerical Analysis of Microstructure Development during Laser Welding Nickel-based Single-crystal Superalloy Part III: Nonequilibrium Solidification Behavior
Authors: Gao Zhiguo
Published: January 2021

The thermal-metallurgical modeling of primary γ gamma phase nonequilibrium solidification behavior during laser welding nickel-based single-crystal superalloy is further developed through coupling of heat transfer model, multicomponent dendrite growth model and nonequilibrium solidification model to evaluate solidification cracking susceptibility and advance the understanding of the material weldability. The useful relationship among welding conditions (laser power, welding speed and welding configuration), weld pool geometry, dendrite selection, dendrite growth, solidification temperature range, solidification cracking susceptibility and weldability are established for welding conditions optimization and microstructure control. It is indicated that for (001) and [100] welding configuration, solidification cracking susceptibility along the solid/liquid interface is symmetrically distributed about the weld pool centerline. It is crystallographically favorable for mitigation of solidification cracking with bimodal distribution of solidification temperature range. By contrast, for (001) and [110] welding configuration, solidification cracking susceptibility is asymmetrically distributed. The solidification cracking susceptibility of the unfavorable [100] dendrite growth region on the right side of the weld pool is higher than that of [010] dendrite growth region on the left side due to the enlargement of solidification temperature range. The mechanism of asymmetrical crystallography-dependent solidification cracking is proposed. Asymmetrical dendrite growth region induces asymmetrical solidification behavior and solidification cracking susceptibility along the solid/liquid interface, although heat transfer is symmetrical. The overall solidification temperature range of (001) and [100] welding configuration is beneficially narrower than that of (001) and [110] welding configuration throughout the weld pool regardless of heat input. The theoretical predictions agree well with the experiment results. In addition, the promising model is also applicable to other single-crystal superalloys with similar metallurgical properties during laser welding or laser cladding.
Preparation and Characterization of Polyimide/TiO2 Nano-composites for Non-lethal Weapon
Authors: Cui Xiaoping
Published: January 2021

A series of Polyimide/TiO2 (PI/TiO2) nano-composites were successfully prepared by incorporating different nano-sized TiO2 contents into PI which derived from pyromellitic dianhydride (PMDA) and a flexible diamine 4,4-bis(3-aminophenoxy)biphenyl (4,3-BAPOBP) via in-situ polymerization and a thermal imidization method. The micromorphology, chemical structure of samples were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR). The SEM results show that when the content of nano-TiO2 is lower, the nano-TiO2 can be distributed uniformly in the matrix by the method of this experiment scheme, and signs of agglomeration have begun to appear when the TiO2 content is 12 wt.%. XRD patterns reveal the crystal structure of TiO2 remains unchanged and stable after being doped into PI matrix, and the TiO2 nano-particles have good compatibility with PI matrix
Influence of shape on power conversion efficiency of Ni-Zn ferrite/piezoelectric magnetoelectric gyrator
Authors: Zhang Jitao , Wang Zhen , Zhang Qingfang , Zhao Hewei , Wu Jie , Tao Jiagui , Jiang Liying , Cao Lingzhi
Published: January 2021

Reducing the demagnetization effects via shape optimization in tri-layer magnetoelectric (ME) composite is an effective way to improve its power transfer conditions. To accomplish this goal, enhanced dynamic piezomagnetic coefficient of Ni0.7Zn0.3Tb0.02Fe1.98O4 ferrite, the tri-layer Ni0.7Zn0.3Tb0.02Fe1.98O4/PZT/Ni0.7Zn0.3Tb0.02Fe1.98O4 ME composites under different L/W ratios with coil wound around for gyrator fabrication were systematically characterized. Measurements of resonance ME responses were carried out for samples with the varying L/W ratio, the weak demagnetization field occurs at the sample with highest L/W ratio, yielding a stronger ME coupling. Experiment results of PE characterizations demonstrated that maximum of 91.3% was achieved under optimum bias and EMR driving in sample with higher L/W=17.5. Therefore, the higher PE is originated from strong dynamic magneto-mechanical response under the shape optimizations. These findings provide the possibility of ME gyrator in high energy conversion power electronics devices.
Model of Optimization solution Based on Generalized Evidence Theory
Authors: Ying Wu
Published: January 2021

In order to solve the application of generalized evidence theory in Engineering, a new generalized basic probability assignment GBPA generation method is proposed in this paper. And on this basis, the selection model of civil aircraft optimization scheme is constructed. Then, taking the optimization scheme of a civil aircraft as an example, it is proved that the method is simple in calculation and clear in physical meaning, which is more suitable for practical application
Physical processes driving intensification of future precipitation in the mid- to high latitudes
Authors: Poujol B , Mooney P A , Sobolowski S P
Published: January 2021

Precipitation is changing as the climate warms, and downpours can become more intense due to the increased water holding capacity of the atmosphere. However, the exact nature of the precipitation response and its characteristics is still not well understood due to the complex nature of the physical processes underlying the formation of clouds and precipitation. In this study, present and future Norwegian climate is simulated at convection-permitting scales with a regional climate model. The future climate is a high emission scenario at the middle of the century. Hourly precipitation is separated into three categories (convective, stratiform, and orographically enhanced stratiform) using a physically-based algorithm. We investigate changes in the frequency, intensity and duration of precipitation events for each category, delivering a more nuanced insight into the precipitation response to a changing climate. Results show very strong seasonality, with significant intensification of autumn precipitation. An increase in convective precipitation frequency and intensity dominates the climate change signal regardless of season. While changes in winter and summer are well explained by thermodynamical theory, the precipitation response in autumn and spring deviates from the idealised thermodynamic response, partly owing to changes in cloud microphysics. These results show that changes in the precipitation distribution are affected in complex ways by the local climatology, terrain, seasonality and cloud processes. They illustrate the need for further and more detailed investigations about physical processes underlying projected precipitation changes and their seasonal and regional dependence.
Index theorem for domain walls
Authors: Ivanov A V
Published: January 2021

The paper is devoted to the discussion of index theorem for domain walls condition. We give an extension of the theorem to the case, when not only Yang–Mills connection components have a jump on some surface of co-dimension 1, but also components of a Riemannian connection, while a metric remains continuous.
Mathematical, detailed and parametric modelling for smart spinal orthoses
Authors: Murzac R , Doicin C V , Ulmeanu M E , Ţurcanu T
Published: January 2021

The paper presents a mathematical model and the design details to manufacture a prototype of a smart orthosis for posture correction while sitting on a chair at your office or at home. The global geometry for developing the mathematical model was obtained by direct measuring a human 3D model, developed by scanning one of the authors’ body and 3D printing it. Based on the mathematical model, the detailed design for the entire product was performed in accordance with the product architecture. The stages of detailed design for the critical systems within the final assembly are also presented in the paper. The posture correction orthosis must be customized for each user, thus, once the design for the critical components has been validated, a parametric design has been generated to facilitate the manufacturing process. The technical solutions are generated and analysed for a vertebral element of the orthosis, representing the critical component of the product. The vertebral element is subject to mechanical stresses, so that a finite element analysis was performed. The geometry of the component and its material were validated by using FEA on the CAD model of the vertebral element. The further work will include research regarding the changes needed for transforming the orthosis into a medical device for spinal column illnesses.
Chemical and mechanical tests on the SiO2-ZnO materials for protective coatings of industrial use
Authors: Mocioiu A M , Băilă D I , Mocioiu O C
Published: January 2021

Many industrial processes, such as chemical process and pharmaceuticals, use aggressive acidic and caustic solution which may result in an early failure of the components of plant. The various corrosion processes in harsh environments could be uniform corrosion, localized corrosion, galvanic corrosion, etc. In order to extend the life of components, a proper material selection is necessary. This direction is intended to address the behaviour of materials due to exposure in harsh environments. The main objective is to develop new vitreous coatings for different kind of materials as metals or glasses in order to protect them against acid attack. SiO2-ZnO materials were prepared by chemical route in order to be used as protective coatings. The SiO2-ZnO materials were investigated by infrared spectroscopy and differential thermal analysis in order to determine their structure and thermal characteristics. SEM and EDS measurements were performed to investigate their structure and morphology. The chemical resistance tests in acid media (HCl and HF) were followed based on STAS and ISO standards and the extraction solutions were tested by ICP-MS in order to identify elements lost during tests. Mechanical tests were performed.
Some aspects of the nitriding process of parts in machine construction
Authors: Mazuru S , Trifan N , Mazuru A
Published: January 2021

Nitriding is the most common and effective surface hardening method. Such chemical-thermal treatment is capable of increasing surface hardness, contact endurance, wear and seizure resistance, as well as heat resistance and corrosion resistance of a wide range of machine parts. This process of surface hardening has found its application in many branches of modern mechanical engineering. The operational requirements for the parts led to the need to replace high-temperature methods of chemical-thermal treatment (carburizing, high-temperature nitrocarburizing, etc.) for hardening processes at lower temperatures (500-650° C), namely nitriding. This replacement was facilitated by the latest technological developments in the field of various nitriding methods. The scientific developments obtained to date make it possible to gradually eliminate such disadvantages of nitriding as a significant duration of the process, increased fragility of the surface layer, insufficient values of contact endurance, and labor intensity of the process [1, 2].
Smart prediction of surface micro-hardness after milling based on fuzzy inference model
Authors: Amira M T , Belloufi A , Abdelkrim M , Abdelkrim F , Mezoudj M
Published: January 2021

The lack of comprehending and control of the micro-hardness of the machined surface is an important obstacle to the use of the milling process. In order to optimize the machining process by milling, this work has focused on the problem of micro-hardness changing of machined surfaces by milling, which has been the subject of several scientific works. A fuzzy inference model was developed to study the influence of cutting conditions (cutting speed, feed per tooth and depth of cut) on the micro-hardness of machined surfaces by milling. The predicted values, obtained by fuzzy model, are compatible with the experimental values, with an average error percentage of 0.63%.
Experimental study towards WIG welded joint. Case study: Repair by welding of X2CrNiMo17-12-2 pipes
Authors: Ionescu F , Solomon Ghe , Voiculescu I , Gârleanu G , Gârleanu D
Published: January 2021

Nowadays, several technological problems were raised by industrial beneficiaries regarding spiral and pipe heat exchangers repairs and thus studies were done in this regard. X2CrNiMo17-12-2, austenitic stainless steel pipes were considered for the experiments on which artificial defects, simulating functioning defects, were done. In order to perform the repair activities on the designed defects, WIG welding process was used and an experimental stand was created. This paper presents some of the difficulties that can occur during the repair by welding of pipes and the defects identified using destructive and non-destructive testing on the probes and samples created for the experimental study scope. Significant conclusions can be drawn; up to a distance of about 100 - 150 mm from the access end, the repair has a good appearance with no serious imperfections.
The composite functional statistical criterion for evaluating the effectiveness of the automatic control process and system
Authors: Akimov A I , Akimova J A , Panchenko V V , Odiehov M M
Published: January 2021

The process of managing and controlling equipment is a broader concept than data transmission. It includes collecting the information about the controlled parameters, transferring the information, its processing, the development of control actions and their transfer to the object in order to bring the controlled parameters back to normal. These tasks are solved by the control and monitoring system. Modern ACMS have not only a larger number of elements, but also a more complex internal structure. Even if all elements of ACMS function are in a reliable way in the process of its operation, the performance of the task assigned to the system cannot be treated as a reliable event. One of the essential features of ACMS is that they are meant to improve the quality of the controlled objects. To quantify the quality of complex systems, effectiveness indicators are used. Indicators of the quality of the system performance of the assigned functions are called the effectiveness of system operation or simply effectiveness. The main idea of evaluating the effectiveness of ACMS is to get the opportunity to compare systems that are identical in purpose, even if they differ from each other in the principles of design and operation. There are certain connections between the individual elements of ACMS, the system as a whole and the controlled object through which they interact with each other. From the point of view of evaluating ACMS effectiveness, the information content of these links is crucial, since the processes of automatic control, for example, in the field of electrical energy production and distribution, are carried out on the basis of information received about the controlled object.
Determination of parameters for automatic decompression of heat and power facility cylinders
Authors: Anatskyi O O , Aulin D O , Bobrytskyi S V , Zhovtiy Y V , Chernenko P V
Published: January 2021

This paper analyzes various types of startup systems used for the heat and power facility start-up. Factors impacting startup characteristics of the heat and power facility were considered. Methods for the modernization of the startup system and possible revamping of auxiliary starting aid devices of locomotive diesel engines without significant design changes by means of cylinder test valve opening were identified. Kinematic diagrams of device gearing for automatic decompression of the heat and power facility cylinders were developed and analyzed. The device requirements were determined, namely, response time, cylinder test valve open and closing torque overriding Tmin=11 Nm. Based on the necessity of torque backup at least 30 % the gear ratio required for the selected engine and its dimensions was calculated.
Determination of rational locomotive operating modes and resource costs based on information from global positioning systems
Authors: Barybin Mykola , Falendysh Anatoliy , Hatchenko Victoria , Kletska Olha , Kiritseva Elena
Published: January 2021

The article is devoted to the study of energy-efficient use of traction rolling stock for driving trains. It deals with the optimal driving mode and the main parameters of traction calculations. Based on the use of GPS/GLONASS satellite navigation units, a method for determining the basic resistance of cars in real time is proposed. The possibility of using the results obtained on locomotives with analog devices and no movement tracking is analyzed. The “Traction Calculations” software package in the C# programming language was modified in order to reduce the time and facilitate calculations of the locomotive traction service. In the course of the study, the equation of the main resistance of the cars of train No. 3612 was determined. On the basis of the uncoupled rolling stock, the dependences of speed, time, heating and current of traction electric motors, fuel consumption by the CHME3 locomotive of the Kharkiv-Sortirovochny locomotive depot for the transportation of cars from the Kharkiv-Sortirovochny station to Merefa station were calculated, with recommendations for the driver to use the position of the driver’s controller in order to reduce costs and fulfill the train schedule.
Improvement of the method of probability evaluation of the failure-free operation of reinforced concrete beams strengthened under load
Authors: Ye Khmil R , Yu Tytarenko R , Blikharskyy Ya Z , Vegera P I
Published: January 2021

The article is dedicated to the study of the load level effect on failure-free operation probability of undamaged rectangular cross-section reinforced concrete beams when their strengthening by the tensile steel reinforcement increasing. The presence of the load level simulates the real structure exploitation conditions at their strengthening. The validation of basic and improved reliability evaluation methods on real beam samples allowed receiving the recommended failure-free operation values P(β). Both techniques are adapted to national standards for the reinforced concrete structure design. The difference between the techniques is the operating method of the random parameter of the load level at the moment of amplification. According to the results of approbation the comparative analysis of the received results is carried out – depending on additional steel bar diameter and the load level at the moment of amplification. The practical significance of the article results is in use of both existing and advanced methods of the probabilities of failure-free operation estimation of reinforced concrete bended elements, strengthened by addition of the stretched steel reinforcement under different load levels, in particular, for accepting higher design levels of reliability.
A study of bearing capacity of reinforced masonry beams with GFRP reinforcement
Authors: Kramarchuk Andrii , Ilnytskyy Borys , Bobalo Taras , Lytvyniak Oksana
Published: January 2021

This article presents the results of experimental researches of bearing capacity and deformability of reinforced masonry beams with combined reinforcement. This study was carried out in the zone of maximum bending moment. The reinforcement A400C and A1000 were used for experimental samples. The combined action of ceramic masonry and reinforcement was ensured at the expense of a cement-sand grout in the joints of masonry and vertical reinforcing meshes in support zones of beams, which were welded to angle bars. Besides that, there was carried out a comparison of the results of experimental researches with calculated values by the active standards of Ukraine. This comparison permits to determine the expediency of the use of the existing design procedure of bearing capacity of reinforced masonry structures with combined double reinforcement. Finally, this scientific work has also presented the conclusions about the possibility of the efficient design of reinforced masonry structures in the effective area of normal forces.
Research of Disclosure of Relief Venting Structures with Polycarbonate Fencing in Conditions of Explosion
Authors: Pozdieiev Serhii , Nizhnyk Vadym , Pidhoretskiy Yuriy , Shvydenko Andriy
Published: January 2021

The article considers the processes of release of the openings of relief venting structures based on honeycomb polycarbonate sheets under action of an explosion. The use of honeycomb polycarbonate sheets enables saving transparent fence against destruction, decreasing risks of human traumatism with glass shards, reduce weight of relief venting structures. There were investigated the conditions of the ratio of the opening sizes of the sections of relief venting structures with honeycomb polycarbonate sheets, under which this opening is reliably released to reduce the pressure during the explosion to safe values. A mathematical model was proposed that establishes a relationship between the value of the explosion pressure and the opening size at which the opening of relief structures with honeycomb polycarbonate sheets. The article proposes a calculation method for designing the sections of relief structures with honeycomb polycarbonate sheets using nomograms. The use of developed method lets significantly simplify calculating for design of relief structures with honeycomb polycarbonate sheets.
Features of determining engagement line of traction gears with different degrees of wear of gear teeth
Authors: Moroz V I , Hromov V I , Bratchenko O V , Logvinenko O A
Published: January 2021

Calculations of strength, forecasting the residual operation life for repairing traction gears (TG) is carried out on the results of modeling their motion characteristic, which is based on the determined coordinates of the contact points of the gear and wheel profile for the period of engagement (engagement line). This article presents results of a study aimed at developing mathematical dependencies for a refined determination of TG engagement line with the established wear of gear teeth. Adequacy verification of proposed mathematical descriptions was carried out based on the results of the study of new TG of ER-2 electric train series. Their comparison with the coordinates of the engagement line, calculated by the traditional method, showed that modelling uncertainty does not exceed 0.06%. As an example of practical use of the received mathematical descriptions, results of research of motion characteristic of new TG of ER-2 electric train series with the established degrees of wear of gear and wheel teeth are presented.
Ways to increase the traction efficiency of modular draft device
Authors: Nadykto V , Kyurchev V , Chaplinskyi A , Ayubov A
Published: January 2021

The versatility of tractors can be increased by using them as a part of a modular draft device (MDD). MDD consists of energetic (EM) and technological (TM) modules. EM is a high-energy tractor with a 2WD or 4WD wheel arrangement and a traction force of 14-16 kN. TM is an additional axle with an active drive of its wheels. By connecting TM to the rear hitch linkage (RHL) of EM, the tractive effort of the entire MDD, which has a 4WD or 6WD wheel arrangement, increases to 32-36 kN. MDD can function as a road-rail vehicle. Depending on the traction resistance, MDD can be used both as part of an EM+TM or as a single EM. According to the research results, it was found that the maximum traction efficiency (TE) of MDD with a 6WD wheel arrangement is about 10% higher than that of MDD with a 4WD wheel arrangement. The TE value of MDD increases with an increase in the inclination of EM rear hitch linkage top link. The increase in MDD’s tractive efficiency is facilitated by an increase in the coefficient of kinematic discrepancy in the drive of the EM and TM wheels from 1.00 to 1.05.
Justification of the parameters of the life-test bench for railway wheelsets
Authors: Raksha S V , Anofriev P G , Kuropiatnyk O S
Published: January 2021

One of the tasks that need to be solved in order to predict the life of wheelsets is to assess the contact strength and wear of their parts. Thus, the purpose of this work is to develop a scheme and justification of the parameters of the life-test bench for railway wheelsets in conditions close to real operating ones. This bench simulates a contact of “wheel-rail” pair as a contact of “wheel-roller” pair. To ensure compliance of the bench tests conditions with the real wheelsets operation conditions we took that the maximum contact pressure in the “wheel-roller” pair is equal to the maximum contact pressure in the “wheel-rail” pair. As results of this study we obtained the dependences of the values of the roller diameter and the working force of the bench on the characteristics of the tested wheelset and proved the mutual influence of these quantities. For railway wheelsets with an axle load of 230.5 kN and wheels with a tread diameter of 957 mm, we obtained the following values of the bench parameters: roller diameter is 75 mm; working force of the bench is 8,375 kN; wheel speed is 500 rpm; number of rollers is 8; test duration is about 220 h.
Mathematical modeling of dynamic loads on the ground robotic complex of special purpose
Authors: Strutinsky V B. , Gurzhii A. M. , Yurchyshyn O. Y.
Published: January 2021

A special technique to study the impact of the discharge on the ground robotic complex equipped with small arms in this article is proposed. The development of the technique is based on mathematical modeling of the dynamic system of the robotic complex. The magnitude and nature of dynamic loads on the ground robotic complex are determined. The experimental sample of the ground robotic complex equipped with small arms has been developed by the authors. Measures to ensure a stable position of the complex and methods of compensation for uncontrolled changes in the position of the complex under dynamic loads are proposed. To study the processes of firing, their individual components are considered: the problem of internal ballistics, the process of movement of the retractable parts of the barrel, dynamic loads on the complex. The conducted study gives the chance to create highly effective samples of special equipment. These are, in particular, military ground-based robotic complexes, which will be competitive by increasing the efficiency of their operation.
Determination of the influence of soil irregularities on dynamic processes in caterpillar engines of a terrestrial robotic complex
Authors: Strutynskyi S V , Semenchuk R V
Published: January 2021

The paper describes the change of the geometry of the caterpillar of the terrestrial robotic complex depending on external factors. It is established that as a result of the action of centrifugal forces the caterpillar elongates, on the surface of the support rollers, the caterpillar repeats their shape, the upper part of the caterpillar acquires a convex shape, and the lower part of the caterpillar repeats the shape of the curve, which determines the unevenness of the soil. The dependence of the caterpillar shape on soil irregularities is established. The peculiarity of the geometry is that on the lower part of the caterpillar there is a ripple with the number of waves between the support rollers 1-2. It is established that the presence of soil irregularities, the harmonic components of the profiles of which have a period of about 4/3 of the distance between the extreme support rollers, leads to the greatest tensile loads in the caterpillar and the corresponding changes in caterpillar length. The dependences determining the elongation of the caterpillar, which is proportional to the square of the amplitude of the harmonic component of the soil roughness of the corresponding period are obtained.
Piezoelectric networks and ferroelectric domains in twistronic superlattices in WS2/MoS2 and WSe2/MoSe2 bilayers
Authors: Enaldiev V V , Ferreira F , Magorrian S J , Fal’ko Vladimir I
Published: January 2021

Twistronic van der Waals heterostrutures offer exciting opportunities for engineering optoelectronic properties of nanomaterials, in particular, due to the formation of moiré superlattice structures. In twisted bilayers of transition metal dichalcogenides moiré superlattice effects are additionally enriched by the lack of inversion symmetry in each monolayer unit cell. Here, we use multiscale modelling to establish a rich variety of confinement conditions for electrons, holes and layer-indirect excitons in twistronic WX2/MoX2 bilayers (X = S,Se). Such trapping of charge carriers and excitons is caused by ferroelectric (interlayer) polarisation and piezoelectric effects generated by the reconstruction of twistronic bilayers into preferential stacking domains separated by domain wall networks. For almost aligned bilayers with anti-parallel (AP) orientation of WX2 and MoX2 unit cells, we find that upon lattice relaxation piezoelectric potential modulation traps holes and electrons in the opposite corners—WMo and XX (tungsten over molybdenum versus overlaying chalcogens)—of hexagonal-shaped 2H (simultaneously WX and XMo) stacking domains, swapping their positions at a twist angle

≳

0.2∘. This crossover happens at such small angles (set by a very small lattice mismatch between WX2 and MoX2) that would impose an alignment accuracy and homogeneity better than 0.1∘ for achieving reproducibility of electronic characteristics of such heterostructures. At the same time, for all angles, XX corners provide 30 meV deep traps for the interlayer excitons. In bilayers with parallel (P) orientation of WX2 and MoX2 unit cells, band edges for both electrons and holes appear in triangular domains, where WX2 chalcogens set over MoX2 molybdenums. We find that, due to a weak ferroelectric polarisation, these triangular domains act as 130 meV deep quantum boxes for interlayer excitons for twist angles

≲

1

∘

, shifting towards XX stacking sites of the domain wall network at larger twist angles.
Effects of Nb concentration and temperature on generalized stacking fault energy of Zr–Nb alloys by molecular dynamics simulations
Authors: Wang Hailian , Pan Rongjian , Tang Aitao , She Jia , Mi Xiaoxi , Wu Lu , Tan Jun
Published: January 2021

The effects of Nb concentration and temperature on the generalized stacking fault energy (GSFE) of basal, prismatic I, pyramidal I and II plane for Zr-Nb alloys are investigated by molecular dynamics simulations (MD). The stable and unstable SFEs of different slip systems show no significant change with the increasing Nb concentration (0, 0.5, 1.0, 1.5, 2.0, and 2.5 at.%) in Zr-Nb alloys at 0 K. Basal, pyramidal I and II planes slip of Zr-Nb alloys prefer to deform by full dislocation with the temperature increases. Additionally, plastic deformation anisotropy of Zr-Nb alloy is improved with the increasing temperature using both embedded atom method (EAM) and angular-dependent potentials (ADP). The present work provides a theoretical basis for understanding enhanced plasticity of Zr-Nb alloys under finite temperature.
Gelatin/Gelatin-modified nano hydroxyapatite composite scaffolds with hollow channel arrays prepared by extrusion molding for bone tissue engineering
Authors: Chen Xiliang , Wu Di , Xu Jingjing , Yan Tingting , Chen Qinghua
Published: January 2021

Bone tissue engineering scaffold has been successfully applied in the field of bone repair, but the major limitation is the delivery of oxygen and nutrients throughout the bulk of engineered tissue, especially for large scaffolds. Researchers have found that scaffolds with hollow channels can effectively solve this problem. We utilized a novel extrusion approach to prepare scaffolds with hollow channel arrays, which has the advantages of economy, continuous production, and high efficiency. The hollow channel scaffolds were composed of gelatin and gelatin-modified nano hydroxyapatite (nHAP). X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and atomic force microscope (AFM) results indicate that the prepared gelatin-modified nHAP are nanorod-like particles with the length of 30∼50 nm and width of 5∼15 nm. The nano particle is composed of crystalline HAP grains with the size less than 10 nm and amorphous phases. A part of OH− or

PO

4

3
−

are replaced by

CO

3

2
−

during preparation process, leading to the transformation of HAP into hydroxyl-carbonated apatite (HCA). The prepared hollow channel scaffolds exhibit much better mechanical properties compared with the sponge porous scaffolds. The axial compressive strength of the hollow channel scaffold with porosity of 51.3 ± 5.2% can reach 25 ± 1.4 MPa, which can meet the mechanical strength requirement as an implant completely. Moreover, the hollow channel scaffold exhibited good in vitro degradability and bioactivity. These results highlight the potential of using gelatin/gelatin-modified nHAP composite scaffolds with hollow channels for bone tissue engineering.
pQCD running couplings finite and monotonic in the infrared: when do they reflect the holomorphic properties of spacelike observables?
Authors: Contreras Carlos , Cvetič Gorazd , Orellana Oscar
Published: January 2021

We investigate a large class of perturbative QCD (pQCD) renormalization schemes whose beta functions β(a) are meromorphic functions of the running coupling and give finite positive value of the coupling a(Q
2) in the infrared regime (‘freezing’), a(Q
2) → a
0 for Q
2 → 0. Such couplings automatically have no singularities on the positive axis of the squared momenta Q
2 ( ≡ − q
2). Explicit integration of the renormalization group equation (RGE) leads to the implicit (inverted) solution for the coupling, of the form

ln
(

Q

2

/

Q

in

2

)
=

(
a
)

. An analysis of this solution leads us to an algebraic algorithm for the search of the Landau singularities of a(Q
2) on the first Riemann sheet of the complex Q
2-plane, i.e., poles and branching points (with cuts) outside the negative semiaxis. We present specific representative examples of the use of such algorithm, and compare the found Landau singularities with those seen after the 2-dimensional numerical integration of the RGE in the entire first Riemann sheet, where the latter approach is numerically demanding and may not always be precise. The specific examples suggest that the presented algebraic approach is useful to find out whether the running pQCD coupling has Landau singularities and, if yes, where precisely these singularities are.
Moving towards high-power thin-disk lasers in the 2 µm wavelength range
Authors: Tomilov Sergei , Hoffmann Martin , Wang Yicheng , Saraceno Clara J
Published: January 2021

Thin-disk lasers (TDLs) have made spectacular progress in the last decades both in continuous-wave (CW) and ultrafast operation. Nowadays, single thin-disk oscillators with >16 kW of CW-power have been demonstrated and ultrafast amplifiers have largely surpassed the kilowatt milestone with pulse energies in the multi-100 mJ range. This amazing development has been demonstrated in the 1 µm wavelength range, using Yb-doped materials and supported by industrially available components. Motivated by both strong scientific and industrial applications, interest in expanding this performance to longer wavelength regions continues to increase. In particular, TDLs emitting directly in the short-wave mid-infrared (SW-MIR) region (2–3 µm) are especially sought after, and although many early studies have been reported, most remained in the proof-of-principle stage and the potential for multi-100 W operation remained undemonstrated. Here, we report on our recent results of a single fundamental-mode CW Ho:YAG thin-disk oscillator with >100 W of power, surpassing previous single-mode TDLs by a factor of >4, and marking a first milestone in the development of high-power SW-MIR TDLs. In optimized conditions, our laser system emitting at ≈2.1 µm reaches an output power of 112 W with 54.6% optical-to-optical efficiency and an M
2 = 1.1. This system is ideally suited for future direct modelocking at the 100 W level, as well as for ultrafast amplification. We start the discussion with a review of the state-of-the-art of TDLs emitting directly in the vicinity of 2 µm, and then discuss difficulties and possible routes both towards ultrafast operation and next possible steps for power scaling.
Friction correction of flow stress-strain curve in the upsetting process
Authors: Obiko Japheth
Published: January 2021

This article reports the effects of friction on the flow stress-strain curve obtained from uniaxial compression test. Uniaxial compression test was done at deformation temperature range of 575 °C–650 °C and strain rates of 0.001 s−1, 0.01 s−1, 0.1 s−1 and 0.5 s−1 to a strain of 0.6 using Gleeble® 3500 thermo-mechanical simulator. The friction parameter was calculated by using the analytical equation from the literature. The study reports the flow stress-strain curve results. The results showed a variation between the measured and the friction corrected flow stress-strain curves. The flow stress variation increased with an increase in strain. This result shows an increase in friction parameter resulting from contact between the die and the workpiece during deformation. The study has shown that the analytical equations used for hot deformation are applicable in analysing warm deformation flow stress-strain curves.
Gradient estimates for a parabolic 𝑝-Laplace equation with logarithmic nonlinearity on Riemannian manifolds
Authors: Wang Yu-Zhao , Xue Yan
Published: January 2021

In this paper, we study gradient estimates for a parabolic

p
p

-Laplace equation with logarithmic nonlinearity, which is related to the

L
p

L^p

-log-Sobolev constant on Riemannian manifolds. We prove a global Li-Yau type gradient estimate and a Hamilton type gradient estimate for positive solutions to a parabolic

p
p

-Laplace equation with logarithmic nonlinearity on compact Riemannian manifolds with nonnegative Ricci curvature. As applications, the corresponding Harnack inequalities are derived.
High perturbations of Choquard equations with critical reaction and variable growth
Authors: Zhang Youpei , Tang Xianhua , Rădulescu Vicenţiu
Published: January 2021

This paper deals with the mathematical analysis of solutions for a new class of Choquard equations. The main features of the problem studied in this paper are the following: (i) the equation is driven by a differential operator with variable exponent; (ii) the Choquard term contains a nonstandard potential with double variable growth; and (iii) the lack of compactness of the reaction, which is generated by a critical nonlinearity. The main result establishes the existence of infinitely many solutions in the case of high perturbations of the source term. The proof combines variational and analytic methods, including the Hardy-Littlewood-Sobolev inequality for variable exponents and the concentration-compactness principle for problems with variable growth.
On the number of hyperbolic Dehn fillings of a given volume
Authors: Jeon BoGwang
Published: January 2021

Let

M

\mathcal {M}

be a

1
1

-cusped hyperbolic

3
3

-manifold whose cusp shape is quadratic. We show that there exists

c
=
c
(

M

)

c=c(\mathcal {M})

such that the number of hyperbolic Dehn fillings of

M

\mathcal {M}

with any given volume

v
v

is uniformly bounded by

c
c

.
A ground-theoretical modal definition of essence
Authors: De Rizzo Julio
Published: January 2021

I provide a case-by-case definition of essential truths based on the notions of metaphysical necessity and ontological dependence. Relying on suggestions in the literature, I adopt a definition of the latter notion in terms of the notion of ground. The resulting account is adequate in the sense that it is not subject to Kit Fine’s famous counterexamples to the purely modal account of essence. In addition, it provides us with a novel conception of truths pertaining to the essence of objects, which might help to dispel doubts on the legitimacy of the notion of essence itself.
Antiapoptotic activity of methyl (3R,4E,6Z,15E)-3-hydroxyoctadecatrienoate in human cervical carcinoma HeLa cells
Authors: Ohno Osamu , Sato Keigo , Honma Ryo , Chiba Ruri , Matsuno Kenji
Published: January 2021

Inhibitors of thapsigargin-induced cell death in human cervical carcinoma HeLa cells were screened among the metabolites of marine organisms. The MeOH extract of the cyanobacterium Rivularia sp. was found to exhibit inhibitory activity. Column chromatography purification was used to isolate methyl (3R,4E,6Z,15E)-3-hydroxyoctadecatrienoate (MHO) as the active compound. MHO was determined to inhibit apoptotic stimuli-induced cell death in HeLa cells.
miR-484 targeting of Yap1-induced LPS-inhibited proliferation, and promoted apoptosis and inflammation in cardiomyocyte
Authors: Xu Ming , Li Xiao-Yong , Song Laichun , Tao Chao , Fang Jihui , Tao Liang
Published: January 2021

Apoptosis and inflammation were the main hallmarks of sepsis-induced cardiomyopathy (SIC). Yes-associated protein isoform 1 (Yap1) and miR-484 were involved in mitochondrial fission and apoptosis, especially proapoptotic roles in SIC. Here, we investigated the role of Yap1 and miR-484 in lipopolysaccharide (LPS)-treated H9c2 cells. Yap1 was downregulated, while miR-484 was elevated by LPS treatment. Cell counting kit-8, flow cytometry, western blotting, and ELISA showed that miR-484 inhibitor significantly improved cell viability, decreased apoptosis, suppressed NLRP3 inflammasome formation, and reduced secretion of inflammatory cytokines TNF-α, IL-1β, and IL-6. Yap1, directly targeted by miR-484 shown in the luciferase assay, was more like a compensatory regulator of LPS stimulation. Knockdown of Yap1 inverted the effects of miR-484 inhibitor, including decreased cell viability, and promoted apoptosis and inflammation. These revealed miR-484 directly targeted mRNA of Yap1 to inhibit cell viability, and promote apoptosis and inflammation in LPS-treated H9c2 cells.
Generation and characterization of monoclonal antibodies against mature hepcidin and its application to neutralization and quantitative alteration assay
Authors: Sakamoto Shinji , Kirinashizawa Mika , Mohara Yumi , Watanabe Yoshihiro
Published: January 2021

Hepcidin regulates the quantity of ferroportin (FPN) on cellular membrane. In our cell assay expressing ferroportin labeled with green fluorescence, FPN was internalized and degraded only after treatment with hepcidin-25, not hepcidin-22 or hepcidin-20, leading to accumulation of cellular iron. Thus we generated murine monoclonal antibodies (mAbs) against hepcidin-25, and then characterized and validated their functions. Among them, several mAbs showed a neutralizing activity that may prevent ferroportin internalization induced by hepcidin-25. To measure hepcidin level in various fluids, mAbs specific for human and rat hepcidin-25 were selected. As for rat, a sandwich ELISA developed using clone rHN1 as capture antibody and biotinylated clone mHW1 as a detection reagent had high sensitivity, allowing for the detection of 1-100 ng/mL of hepcidin-25. Rat hepcidin-25 level in plasma was measured at an average concentration of 63.0 ng/mL in healthy condition, and at 218.2 ng/mL after stimulation of lipopolysaccharide.
HunFlair: an easy-to-use tool for state-of-the-art biomedical named entity recognition
Authors: Weber Leon , Sänger Mario , Münchmeyer Jannes , Habibi Maryam , Leser Ulf , Akbik Alan
Published: January 2021

Named entity recognition (NER) is an important step in biomedical information extraction pipelines. Tools for NER should be easy to use, cover multiple entity types, be highly accurate and be robust toward variations in text genre and style. We present HunFlair, a NER tagger fulfilling these requirements. HunFlair is integrated into the widely used NLP framework Flair, recognizes five biomedical entity types, reaches or overcomes state-of-the-art performance on a wide set of evaluation corpora, and is trained in a cross-corpus setting to avoid corpus-specific bias. Technically, it uses a character-level language model pretrained on roughly 24 million biomedical abstracts and three million full texts. It outperforms other off-the-shelf biomedical NER tools with an average gain of 7.26 pp over the next best tool in a cross-corpus setting and achieves on-par results with state-of-the-art research prototypes in in-corpus experiments. HunFlair can be installed with a single command and is applied with only four lines of code. Furthermore, it is accompanied by harmonized versions of 23 biomedical NER corpora.

Availability and implementation

HunFlair ist freely available through the Flair NLP framework (https://github.com/flairNLP/flair) under an MIT license and is compatible with all major operating systems.

Supplementary information

Supplementary data are available at Bioinformatics online.