bluuebunny/crossref_metadata_2025 huggingface dataset:
University instructors’ knowledge for teaching organic chemistry mechanisms
Authors: Zotos Eleni K. , Tyo Jordan J. , Shultz Ginger V.
Published: April 2021

Many recent studies document the difficulties that students experience when learning organic chemistry, often due to the complex visualization and reasoning skills required to successfully understand the ways molecules interact in specific environments. Many of these studies call on instructors to improve their teaching strategies to support students’ learning of organic chemistry mechanisms, but few have focused on instructors’ knowledge of organic chemistry and how they use their knowledge to teach this topic. To investigate university instructors’ knowledge for teaching organic chemistry mechanisms, we utilized a task-based think-aloud interview protocol where graduate teaching assistants (GTAs) and faculty instructors assessed authentic undergraduate student responses to three organic chemistry mechanism questions. We describe this knowledge for a substitution, an acid–base, and an addition reaction. For all mechanisms, we describe how GTA participants’ knowledge for teaching related to their content knowledge. This result revealed differences between GTA and faculty participants’ knowledge for teaching mechanisms that were specific to features of each mechanistic task. For example, in a substitution reaction question, all faculty participants recognized and explained issues with a student's drawing of a transition state and apparent understanding of partial bonds. These features of the student's drawing were not recognized by any GTA participants, who focused instead on the student's prior knowledge about ionic bonding. These findings qualitatively illuminate strengths and weaknesses in graduate students’ knowledge for teaching which can guide how they are supported as instructors.
In situ growth of ZIF-8 on gold nanoparticles/magnetic carbon nanotubes for the electrochemical detection of bisphenol A
Authors: Li Hexiang , Zhu Fawei , Xiang Jun , Wang Fangbin , Liu Qi , Chen Xiaoqing
Published: April 2021

We herein report a facile and scalable strategy for the fabrication of a MOF based composite by in situ growing ZIF-8 on AuNPs loaded mCNTs. And an electrochemical sensor was successfully developed based on the composite for the detection of BPA.
Green and sensitive spectrofluorimetric determination of Remdesivir, an FDA approved SARS-CoV-2 candidate antiviral; application in pharmaceutical dosage forms and spiked human plasma
Authors: Elmansi Heba , Ibrahim Adel Ehab , Mikhail Ibraam E. , Belal Fathalla
Published: April 2021

Fluorescence spectroscopy is a sensitive, simple, and economic analytical tool with high through output suitable for the Quality Control of COVID-19 drugs.
A QM/MM study on the origin of retro-aldolase activity of a catalytic antibody
Authors: De Raffele Daria , Martí Sergio , Moliner Vicent
Published: April 2021

The retro-aldolase mechanism of methodol catalysed by the catalytic antibody 33F12 is described based on the exploration of the free energy landscape obtained with QM/MM methods.
Unusual π–π interactions directed by the [{(C6H6)Ru}2W8O30(OH)2]6− hybrid anion
Authors: Mukhacheva Anna A. , Komarov Vladislav Yu. , Kokovkin Vasily V. , Novikov Alexander S. , Abramov Pavel A. , Sokolov Maxim N.
Published: April 2021

The [{(C6H6)Ru}2W8O30(OH)2]6− hybrid anion as a new type of π–π stacking induced building block and methanol oxidation precatalyst.
Bond-forming and electron-transfer reactivity between Ar2+ and N2
Authors: Armenta Butt Sam , Price Stephen D.
Published: April 2021

Electron transfer between Ar2+ and N2 involves both complexation and direct dynamics; a stripping-style pathway generates ArN+.
Photon-induced deactivations of multiple traps in CH3NH3PbI3 perovskite films by different photon energies
Authors: Herawati Asmida , Lin Hui-Ching , Chan Shun-Hsiang , Wu Ming-Chung , Lim Tsong-Shin , Chien Forest Shih-Sen
Published: April 2021

Two types of electron traps were identified in MAPbI3 perovskite; one can be deactivated by 633 nm and 405 nm illuminations, whereas the other one only by 405 nm illumination. The energy levels of both traps were beneath the conduction band minimum.
Enhancing the static green up-conversion luminescence of NaY(MoO4)2:Yb/Er microcrystals via an annealing strategy for anti-counterfeiting applications
Authors: Zhang Xiangyu , Wu Jialing , Wang Peng , Gao Jie , Gao Feng , Gao Dangli
Published: April 2021

Up to 37-fold enhanced luminescence was achieved when NaY(MoO4)2:Yb3+/Er3+ micro-crystals were annealed at 700 °C. Their high-purity green emission makes them suitable for the imaging of latent fingerprints and for anti-counterfeiting applications.
New insights into the digestion and bioavailability of a high-melting-temperature solid triacylglycerol fraction in bovine milk fat
Authors: Ren Qingxi , Fu Ling , Dudu Olayemi E. , Zhang Rui , Liu Haiyan , Zheng Zhiqiang , Ma Ying
Published: April 2021

Short-term consumption of a high-melting-temperature solid TAG fraction (30S) in milk fat did not bring obvious health risks. Conversely, it led to positive physiological and biochemical activities by suppressing appetite and increasing fecal loss.
N-Doped carbon as the anode and ZnCo2O4/N-doped carbon nanocomposite as the cathode for high-performance asymmetric supercapacitor application
Authors: Gunasekaran Sivagaami Sundari , Badhulika Sushmee
Published: April 2021

Herein, we report a one-pot hydrothermal assisted synthesis of ZnCo2O4/N-doped carbon nanocomposite (ZC/NC) for high-performance asymmetric supercapacitor applications.
Homochiral one-dimensional ABX3 lead halide perovskites with high-Tc quadratic nonlinear optical and dielectric switchings
Authors: Peng Hang , Liu Yu-Hua , Huang Xue-Qin , Liu Qin , Yu Zi-Hong , Wang Zhong-Xia , Liao Wei-Qiang
Published: April 2021

Two new homochiral 1D ABX3-type lead-halide perovskites exhibit dual dielectric and quadratic nonlinear optical switchings at high temperatures.
Nickel-catalyzed asymmetric reductive cross-coupling of α-chloroesters with (hetero)aryl iodides
Authors: DeLano Travis J. , Dibrell Sara E. , Lacker Caitlin R. , Pancoast Adam R. , Poremba Kelsey E. , Cleary Leah , Sigman Matthew S. , Reisman Sarah E.
Published: April 2021

A Ni-catalyzed enantioselective reductive cross-coupling of α-chloroesters and (hetero)aryl iodides is reported. A MLR model was developed to quantitatively relate the influence of the α-chloroester substrate and ligand on enantioselectivity.
Cooperative copper-squaramide catalysis for the enantioselective N–H insertion reaction with sulfoxonium ylides
Authors: Furniel Lucas G. , Echemendía Radell , Burtoloso Antonio C. B.
Published: April 2021

The first examples of a highly efficient and enantioselective carbene-mediated insertion reaction, from a sulfur ylide, are described.
Covalent and non-covalent albumin binding of Au(i) bis-NHCsviapost-synthetic amide modification
Authors: Sen Sajal , Perrin Mark W. , Sedgwick Adam C. , Lynch Vincent M. , Sessler Jonathan L. , Arambula Jonathan F.
Published: April 2021

Au(i) bis-N-heterocyclic carbenes (NHCs) functionalized using an amide linker were found to bind to human serum albumin (HSA) in covalent and non-covalent fashion. The solubility andin vitroanti-cancer activity of these new conjugates were studied.
Boosting the synthesis of value-added aromatics directly from syngas via a Cr2O3 and Ga doped zeolite capsule catalyst
Authors: Wang Yang , Gao Weizhe , Wang Kangzhou , Gao Xinhua , Zhang Baizhang , Zhao Heng , Ma Qingxiang , Zhang Peipei , Yang Guohui , Wu Mingbo , Tsubaki Noritatsu
Published: April 2021

The single-pass conversion of syngas into para-xylene was realized using a bifunctional catalyst Cr2O3/Ga-ZSM-5@SiO2. The Ga species facilitates the methanol consumption process by C–C coupling optimization, enhancing the yield of the target aromatics.
The environmental performance of a fossil-free ship propulsion system with onboard carbon capture – a life cycle assessment of the HyMethShip concept
Authors: Malmgren Elin , Brynolf Selma , Fridell Erik , Grahn Maria , Andersson Karin
Published: April 2021

Pre-combustion onboard carbon capture could be part of lowering the environmental impact from the shipping sector.
The inner and outer bounds on the capacity of the 3‐user GBC‐SKT with unequal state variances
Authors: Ghabeli Leila
Published: April 2021

The “Gaussian BroadCast channel (GBC) with States non‐causally Known at the Transmitter” (GBC‐SKT) introduces Gaussian broadcast channel with additive i.i.d. Gaussian states non‐causally known at the transmitter. In this model additive interferences on links are considered as states which are only non‐causally known to the transmitter. Such cases are encountered in, e.g., wireless multiple‐antenna multicasting scenario. Previously the approximate capacity of the K‐user GBC‐SKT has been studied where all states but one are assumed to have the same variance. In this work, the capacity of the 3‐user GBC‐SKT channel communicating only common messages is studied. All three states are assumed to have different variances. The key point is how to simultaneously pre‐code the common message against three states. Two transmission strategies are proposed by combination of power‐sharing and time‐sharing methods and two inner bounds are derived. From analytical and simulation results it is seen that one inner bound outperforms the other inner bound. Moreover, the outer bound on the capacity of this channel is driven and the conditions on the state variances for which, the capacity of the 3‐user GBC‐SKT channel is derived to within 1 bpcu, are extracted.
Learning view‐invariant features using stacked autoencoder for skeleton‐based gait recognition
Authors: Hasan Md Mahedi , Mustafa Hossen Asiful
Published: April 2021

Human gait recognition in a multicamera environment is a challenging task in biometrics because of the presence of the large pose and variations in illumination among different views. In this work, to address the problem of variations in view, we present a novel stacked autoencoder for learning discriminant view‐invariant gait representations. Our autoencoder can efficiently and progressively translate skeleton joint coordinates from any arbitrary view to a common canonical view without requiring the prior estimation of the view angle or covariate type and without losing temporal information. Then, we construct a discriminative gait feature vector by fusing the encoded features with two other spatiotemporal gait features to feed into the main recurrent neural network. Experimental evaluations of the challenging CASIA A and CASIA B gait datasets demonstrate that the proposed approach outperformed other state‐of‐the‐art methods on single‐view gait recognition. In particular, the proposed method achieved 46.31% and 33.86% average correct class recognition on probe set ProbeBG and ProbeCL, respectively, of the CASIA B dataset while considering the view variation; this is 0.3% and 30.68% higher than previous best‐performing methods. Furthermore, in cross‐view recognition, our method shows better results over other state‐of‐the‐art methods when the view‐angle variation is large than 36°.
Modelling power amplifier impairments in mmWave phased‐array systems
Authors: Maletic Nebojsa , Grass Eckhard
Published: April 2021

This letter presents an analytical framework to study the distortion effect of power amplifiers (PA) in a single‐stream millimetre wave (mmWave) system with a radio‐frequency beamforming architecture. A third‐order nonlinearity PA model is used. The impact of PA nonlinearity on the transmitter performance is evaluated by means of its normalised mean square error. Also, the effect of PA compression on the system capacity in a line‐of‐sight channel is analysed. All analytical results are supported with Monte‐Carlo simulations.
Virtual current vector‐based method for inverter open‐switch and open‐phase fault diagnosis in multiphase permanent magnet synchronous motor drives
Authors: Trabelsi Mohamed , Semail Eric
Published: April 2021

This paper presents a diagnostic method of inverter open‐switch and open‐phase faults in multiphase permanent magnet synchronous motor (PMSM) drives. First defined are adequate variables called virtual current vectors. The projection of the zero‐sequence current component on these variables was used to define two simple fault indices. High sensitivity to fault is thus induced but with a good robustness to transient states and variation of machine parameters. The mathematical development of the proposed method is provided and supported by experimental tests conducted on two prototypes of multiphase machines in the laboratory: sinusoidal and bi‐harmonic PMSMs. The experimental results confirm the effectiveness and the robustness of the proposed method and its capability to detect the single and multiple open‐switches and open‐phase faults in the electric drive.
Pedestrian re‐identification based on attribute mining and reasoning
Authors: Li Chao , Yang Xiaoyu , Yin Kangning , Chang Yifan , Wang Zhiguo , Yin Guangqiang
Published: April 2021

The high‐level semantic information extracted from the pedestrian attribute feature is an important element for pedestrian recognition. Pedestrian attribute recognition plays an important role in both intelligent video surveillance and pedestrian re‐identification promoting the convenience of searching and performance of model. This paper tries finding a practical method to improve the performance of the pedestrian re‐identification by combining pedestrian attributes and identities. The multi‐task learning method combines pedestrian recognition and attribute information in a direct way that considers the correlation between pedestrian attributes and identities but ignores the principle and degree of such correlation. To solve this problem, a new pedestrian recognition framework based on attribute mining and reasoning is proposed in this paper. To enhance the expression ability of attribute features, it designs spatial channel attention module (SCAM) based on attention mechanism to extract features from every attribute. SCAM can not only locate the attributes on the feature map, but also effectively mine channel features with a higher degree of association with attributes. In addition, both spatial attention model and channel attention model are integrated by multiple groups of parallel branches, which further improve the network performance. Finally, using the semantic reasoning and information transmission function of graph convolutional network, the relationship between attribute features and pedestrian features can be mined. Besides, pedestrian features with stronger expression ability can also be obtained. Experiment work is conducted in two databases, DukeMTMC‐reID and Market‐1501, which are commonly used in pedestrian recognition tasks. On the Market‐1501 dataset, the final effect of the algorithm model CMC‐1 can reach 94.74%, and mAP can reach 87.02%; on the DukeMTMC‐reID dataset, CMC‐1 can reach 87.03%, and mAP can reach 77.11%. The results show that our method is at the top of the existing pedestrian recognition methods.
Practical Investigation of a MIMO radar system capabilities for small drones detection
Authors: Yang Fawei , Xu Feng , Fioranelli Francesco , Le Kernec Julien , Chang Shaoqiang , Long Teng
Published: April 2021

The latest progress of the multiple‐input multiple‐output (MIMO) radar system developed for small drones detection at Beijing Institute of Technology is presented herein. A low‐cost S‐band MIMO scanning radar system is designed for the detection of small drones. A practical design optimisation and implementation of a sparse array covering the whole airspace, and a target‐based MIMO radar array calibration method to improve the signal‐to‐noise ratio of the target are proposed. An experiment in the microwave chamber was conducted to verify the designed sparse‐array beam‐pattern, and measurement campaigns for small drones were performed to test the system performance where the radar achieved detection and tracking of a small DJI‐Phantom 4 drone at a range of up to 5 km. Target features, including micro‐Doppler and radar cross‐section signatures were extracted to assist target classification. The experimental results indicate that the system has promising capability in small drones detection and tracking, despite the challenges of low dwell time on targets due to the scanning nature of the system.
Pathway‐based protein–protein association network to explore mechanism of α‐glucosidase inhibitors from Scutellaria baicalensis Georgi against type 2 diabetes
Authors: Wang Le , Diwu Wenbo , Tan Nana , Wang Huan , Hu Jingbo , Xu Bailu , Wang Xiaoling
Published: April 2021

Natural products have been widely used in the treatment of type 2 diabetes (T2D). However, their mechanisms are often obscured due to multi‐components and multi‐targets. The authors constructed a pathway‐based protein–protein association (PPA) network for target proteins of 13 α‐glucosidase inhibitors (AGIs) identified from Scutellaria baicalensis Georgi (SBG), designed to explore the underlying mechanisms. This network contained 118 nodes and 1167 connections. An uneven degree distribution and small‐world property were observed, characterised by high clustering coefficient and short average path length. The PPA network had an inherent hierarchy as C(k)∼k−0.71. It also exhibited potential weak disassortative mixing pattern, coupled with a decreased function Knn (k) and negative value of assortativity coefficient. These properties indicated that a few nodes were crucial to the network. PGH2, GNAS, MAPK1, MAPK3, PRKCA, and MAOA were then identified as key targets with the highest degree values and centrality indices. Additionally, a core subnetwork showed that chrysin, 5,8,2′‐trihydroxy‐7‐methoxyflavone, and wogonin were the main active constituents of these AGIs, and that the serotonergic synapse pathway was the critical pathway for SBG against T2D. The application of a pathway‐based protein–protein association network provides a novel strategy to explore the mechanisms of natural products on complex diseases.
New analysis of the ρ-class bursts, known as the “heartbeat” of GRS 1915+105: Pulse profile and spectral properties
Authors: Mineo T. , Massa F. , Massaro E. , Feroci M.
Published: April 2021

Context. We present the results of a new analysis of three long Rossi-XTE observations of the microquasar GRS 1915+105 in the ρ class, performed in 1997, 1999, and 2000, and characterized by different peak profiles. The first data set, labeled G-1, is dominated by a single peak, while in the third observation (G-3), all bursts show a clearly detectable couple of peaks. The second observation (G-2) shows an intermediate structure with a single peak and an emerging shoulder on the decay side.

Aims. We devised a new procedure to obtain mean burst profiles in every energy channel independently of the recurrence time intervals of the bursts, variable from 45 s to 53 s in the considered observations, with the aim of investigating the different features of peaks and the eventual spectral variations.

Methods. All the bursts were aligned at a common time bin on the decaying portion of the bursts that is stable in simultaneous light curves at different energies. An averaging algorithm was then applied without modifying the statistical properties or scaling the burst lengths. We analyzed the peak amplitude ratios and the dependence of their delays on energy. The spectral distributions were evaluated for the various components: a stable multi-temperature disk plus a power law Comptonization component was used for the baseline emission and temperature differences of peak components were evaluated with the inclusion of an additional blackbody.

Results. In addition to the well-observed double peak (P1 and P2) pattern, we detected a third small peak (P3) in the structured G-3 light curve. This peak, differently from the other two, exhibits a fast rising and a slower exponential decay, with a e-folding time constant of 1.32 s. The blackbody temperatures of P2 and P3 are higher than P1 and the power law spectrum of P3 is the flattest one.

Conclusions. The time and spectral behavior of P3 is interpreted as a signature of a relatively hot plasma outflow from the disk into the corona and its duration is consistent with the crossing timescale of the particles through the corona where electrons radiate.
O-bearing complex organic molecules at the cyanopolyyne peak of TMC-1: Detection of C2H3CHO, C2H3OH, HCOOCH3, and CH3OCH3
Authors: Agúndez M. , Marcelino N. , Tercero B. , Cabezas C. , de Vicente P. , Cernicharo J.
Published: April 2021

We report the detection of the oxygen-bearing complex organic molecules propenal (C2H3CHO), vinyl alcohol (C2H3OH), methyl formate (HCOOCH3), and dimethyl ether (CH3OCH3) toward the cyanopolyyne peak of the starless core TMC-1. These molecules were detected through several emission lines in a deep Q-band line survey of TMC-1 carried out with the Yebes 40m telescope. These observations reveal that the cyanopolyyne peak of TMC-1, which is a prototype of a cold dark cloud rich in carbon chains, also contains O-bearing complex organic molecules such as HCOOCH3 and CH3OCH3, which have previously been seen in a handful of cold interstellar clouds. In addition, this is the first secure detection of C2H3OH in space and the first time that C2H3CHO and C2H3OH have been detected in a cold environment, adding new pieces to the puzzle of complex organic molecules in cold sources. We derive column densities of (2.2 ± 0.3) × 1011 cm−2, (2.5 ± 0.5) × 1012 cm−2, (1.1 ± 0.2) × 1012 cm−2, and (2.5 ± 0.7) × 1012 cm−2 for C2H3CHO, C2H3OH, HCOOCH3, and CH3OCH3, respectively. Interestingly, C2H3OH has an abundance similar to that of its well-known isomer acetaldehyde (CH3CHO), with C2H3OH/CH3CHO ∼ 1 at the cyanopolyyne peak. We discuss potential formation routes to these molecules and recognize that further experimental, theoretical, and astronomical studies are needed to elucidate the true formation mechanism of these O-bearing complex organic molecules in cold interstellar sources.
Modelling of Selective Laser Melting Process of Quartz Glass at Elevated Temperatures
Authors: Gridnev M.A. , Khmyrov R.S. , Gusarov A.V.
Published: April 2021

Selective laser melting (SLM) to date is the method of additive manufacturing allowing fabricating products from powder layer-by-layer according to a 3D model. However, when applying this method to fragile materials, parts crack while fabricating due to high temperatures. Quartz glass is a promising material for fabricating products by SLM without cracks due to a low thermal expansion. However, quality of fabricated material differs from the fused cast ones. This article aims to test the method of SLM with preheating to improve the material quality. Experiments on single track formation in SLM are analysed by modelling the coupled processes of heat transfer and powder consolidation in the laser-interaction zone. The mathematical model is validated by the experiments. It is shown that the preheating can improve the material quality and increase the process productivity but overheating may result in undesirable crystallization.
Harmonic Progression in Bioinformatics and Recurrent Series in Inherited Biostructures
Authors: Verevkin Vladimir , Petoukhov Sergey
Published: April 2021

The article is devoted to the study of new approaches to the development of mathematical models in genetic biomechanics, which studies the structural relationships of the genetic coding system with genetically inherited biological forms. More specifically, we are talking about models based on the recurrent harmonic progression whose connection with the information sequences of DNA molecules in the genomes of higher and lower organisms was recently revealed. In particular, the article describes previously unknown connections of the function of natural logarithms with the structures of the molecular genetic system, which allow modelling the main psychophysical logarithmic law by Weber-Fechner and also many other logarithmic structures in genetically inherited biological systems. In physics, the harmonic progression is traditionally considered, first of all, as related to standing waves in resonators. Our results are correlated with Frohlich’s vibration-resonant theory about collective quantum effects and long-range communication in biological systems.
Modelling Biomolecular Structures in Categorical Systems Theory
Authors: Tolokonnikov Georgy
Published: April 2021

In the systemic movement there exist numerous approaches to systems, the most profound of which is the theory of functional systems by Anokhin, which remained largely intuitive science until his pioneering works. The basic principles of functional systems are formalized with the help of the convolutional polycategories in the form of categorical systems theory, which embraced the main systemic approaches, including the traditional mathematical theory of systems. Convolutional polycategories can be built using categorical splices that directly model the external and internal parts of systems. For an algebraic biology using the categorical theory of systems in relation to systemic constructions, the main task of which is to predict the properties of organisms from the genome using strict algebraic methods, new categorical methods are proposed that are widely used in categorical systems theory. These methods are based on the theory of categorical splices, with the help of which the behaviour of quantum-mechanical particles is modelled, in particular, within the framework of the proposed representation of molecules, including RNA and DNA, as categorical systems. Thus, new algebraic and categorical methods (associative algebras with identities, PROP, categorical splices) are involved in the analysis of the genome. The paper presents new results on these matters.
Different-Scale Simulation of Flows in Porous Media
Authors: Trapeznikova Marina , Churbanova Natalia , Chechina Antonina
Published: April 2021

The paper considers the development of algorithms for an adequate description of processes of different scales in porous media. The choice of a computational technique is determined by the reference size of the problem being solved. Models of porous medium flow under Darcy’s law, neglecting the medium microstructure, are used for the simulation at macro-scale. While at micro-scale, a direct description of fluid flow in porous channels with complex geometry by means of gas dynamic equations is used. In the first case the proposed model of non-isothermal multiphase multicomponent flow in a porous medium includes the mass balance and total energy conservation equations modified by analogy to the known quasi-gas dynamic equations. The model features are the introduction of minimal reference scales in space and in time and the change of the system type from parabolic to hyperbolic to increase the stability of explicit difference schemes applied for approximation. In the second case the dimensionless form of the quasi-gas dynamic system with pressure decomposition, developed by the authors earlier, is adapted to the simulation of flows in the pore space. The fictitious domain method is proposed to reproduce the core microstructure. The developed approaches have been verified by test predictions.
Excitation of Some Nitrogen-Like Ions: Calculations and Comparison with Measurements
Authors: Nadykto O.B. , Nadykto B.A. , Nadykto A.B.
Published: April 2021

Electronic energies of one-electron excited states 1s22s22p2ns 4P, 1s22s22p2ns 2P, 1s22s22p2np 4S, 1s22s22p2np 2S, 1s22s22p2np 4P, 1s22s22p2np 2P, 1s22s22p2np 4D, 1s22s22p2np 2D, 1s22s22p2nd 4P, 1s22s22p2nd 2P, 1s22s22p2nd 4D, 1s22s22p2nd 2D, 1s22s22p2nd 4F, 1s22s22p2nd 2F of nitrogen-like ions with n=3-12 and Z=7-50 have been calculated. For all the aforementioned electronic configurations, fine-structure levels have been determined for states with different total momentum J. The comparison of theoretical results with the available experimental data shows that theory and measurements agree well. In particular, relative accuracy of 10-4 has been achieved in the electronic energy of N-like at Z > 10, while the typical deviation in the calculated fine-structure levels from experimental data is in the order of 10-2
Acoustic Safety Management at the Locksmith’s Workplace Mechanic-Repairman to Replace the Filter Material in the Technological Process of Obtaining of Apatite Concentrate
Authors: Chalovskaya Ekaterina , Kaverzneva Tatiana , Skripnik Igor , Senchenko Vladimir , Klochihin Ilya
Published: April 2021

In this work, measures are being developed to reduce the noise level at the workplace of a mechanic-repairman to replace filter cloth. Based on the results of production control and a thorough assessment of working conditions, the source of noise was determined to be the VDN-17 fan. The analysis of Russian and foreign studies in the field of the negative impact of noise on the human health and methods of dealing with industrial noise has been carried out. As a result, a technical method of reducing negative impact of noise was selected and the acoustic efficiency of the muffler for the VDN-17 fan was calculated.
Regional Investment Attractiveness’s Model Analysis at the Heart of Russian Investment Policy
Authors: Mitrofanov Evgenii , Kulagina Alevtina , Panferova Liya
Published: April 2021

The article analyzes the investment attractiveness of regions of the Volga Federal District in the Russian Federation using the principal component method. Indicators are selected characterizing investment attractiveness of Russian regions of the Volga Federal District. Functional dependence of the selected indicators are defined, based on which the estimation of level of investment appeal of regions of the Volga Federal District and their clustering. Recommendations for improving the investment policy of Russian regions are given.
Development and Power Calculation of a Grinding Wheel Design for Ultra-High-Speed Grinding
Authors: Rechenko Denis , Kamenov Renat
Published: April 2021

Increasing the structural reliability at ultra-high-speed grinding is an important problem because it defines safety of metalworking. The purpose of work is to achieve the cutting speed up to 400-500 m/s by developing a new design of the grinding wheel with the possibility of using different grinding materials. Grinding wheel design for ultra-high-speed grinding was developed based on calculations carried out using the tear design method, which allows determining the maximum possible circumferential speed, and finite element method used to determine the equivalent stresses, plastic deformations, circumferential and radial movements . The possibility of development of a grinding wheel design for ultra-high-speed grinding has been tested experimentally. The developed designs of grinding wheels show may poddibly be used on super high-speed technological equipment for processing of parts made of hard-to-machine materials. Calculations and comprehensive experimental tests of the design of grinding wheels for ultra-high-speed grinding carried pit in this work allow determining the serviceability and the maximum possible cutting speed and provide useful information for the further development of grinding tools.
Modeling of Non-Stationary Processes When Cutting Hard-to-Process Materials
Authors: Grigoriev Sergey , Migranov Mars , Seitkulov Abdumalik
Published: April 2021

In the conditions of high-speed processing of parts of complex configuration, with a large end and longitudinal length, from hard-to-work steels and alloys, it is difficult to ensure the wear resistance of the cutting tool in the aisles of one technological passage. To ensure the appropriate quality indicators of the surface layer, it is impossible to replace a worn-out cutting tool. In connection with the above, the problem of ensuring the operability (wear resistance) of the cutting tool is acute. The results of theoretical and experimental studies of contact phenomena in blade cutting based on the thermodynamics of non – equilibrium processes and from the standpoint of self-organization of the tribosystem are presented. the developed thermodynamic model of blade processing with variable cutting modes (non-stationary) allows to minimize the wear of the cutting tool and generally increase production efficiency by accelerating the drive of the main movement of the metal-cutting machine.
Suction effects on the tensile strength and unconfined compression of unsaturated soils
Authors: Roque Pedro , Motta Mariana , de Campos Tácio
Published: April 2021

The soil-water characteristic curve is an important relation of unsaturated soils, that expresses the variation of the amount of water retained in the soil as a function of its suction. In these soils, drying or wetting can have a great influence on their resistance parameters. This work presents and discusses the effects of increased suction on the tensile strength and unconfined compression of unsaturated soils. Suction was evaluated using the filter paper and the dew point technique, while the resistance parameters were obtained through the “Brazilian Test” and uniaxial compression. Three different soils from Rio de Janeiro were studied: two young residual soils, in which the influence of the soil structure was also verified through tests on undisturbed and reconstituted samples, and a colluvial soil. The results allowed to conclude that the increase of suction, in a first moment, generates an increase in the resistance parameters of these soils. With the continuation of the drying process, the mechanical behaviour of the soils varied, being able to maintain the resistance or showing a drop related to high suction values.
Loading rate effect on mechanical properties of an unsaturated silty sand
Authors: Barahona Christian , Sandi Luis , Rojas Juan Carlos , Gemmina Di Emidio , Bezuijen Adam , Cornellis Wim
Published: April 2021

This paper presents the results of an experimental study on the effects of testing rate on stress-strain behavior and volumetric changes of soil. A series of suction-controlled triaxial tests has been performed on reconstituted specimens of a silty sand (SM), at different stress-rates and strain-rates, respectively. The stress-strain paths were applied by using a modified version of a Bishop and Wesley device (USPv2), capable of applying independently pore-water and air pressure at both ends of the soil sample. During the isotropic compression stages loading rates of 2 and 32 kPa/h have been applied under constant suction values of 15 and 45 kPa. The drained deviator stages were conducted at the same suction levels under strain rates of 0.25 and 2.50 %/h. Results are presented in terms of applied loading rates as a function of the specimens specific volume, preconsolidation pressure, soil compressibility and deviatoric stress against strain rate. A comparison of results was made to a former study, under similar testing conditions of suction and loading rates at University of Napoli Federico II. The effect of loading rate on the soil behavior seems to have an insignificant effect on the specific volume variations, for the imposed values during the testing campaign.
Modeling the soil-water retention curves for highly deforming soils
Authors: Rojas Eduardo , Horta Jaime , Pérez-Rea María de la Luz
Published: April 2021

A porous-solid model based on the grain and pore size distributions of the soil is coupled with a mechanical model to simulate the soil-water retention curves while the material is deforming. During the determination of the main drying curve, the soil is subjected to high suctions which induce important volumetric deformations. These volumetric deformations modify the pore size distribution of the sample affecting both the drying and the wetting retention curves. Although, most deformation occurs at drying, the drying curve is only slightly affected by soil deformation. In contrast, the wetting curve shows important shifting when volume change is considered.
Matric suction effect on distribution of stresses caused by vehicle wheels on a bare silty sand
Authors: Torrico Bravo Juan Alfredo , Miranda Salvador , Cornellis Wim , Rojas Juan Carlos , Bezuijen Adam , Di Emidio Gemmina
Published: April 2021

-Soil compaction in cropping systems, caused by the external pressure of machinery, creates impermeable layers that restrict water and nutrient cycles reducing agricultural production. To evaluate the matric suction effects on distribution with depth of stresses in a soil, caused by the use of agricultural machinery, Jet Fill tensiometers were installed at two different depths (i.e. 0.15 m, 0.30 m) in a soil profile constituted by silty sand with gravel (SM); to register the increments on subsoil vertical stresses, two miniaturized load cells (i.e. 16. 5 mm in diameter) were installed in a horizontal position under the centre line of the vehicle wheels’ path, at approximately 0.15 m and 0.30 m depth. Care was taken to calibrate the load cells in field conditions. A vehicle was made to pass over the soil surface, at a speed less than 5 km/h; the tyre inflation pressure applied on wheel was 380 kPa. Response of load cells to vehicle loading was evaluated at different average matric suction measured on soil profile. Finally, measured stresses have been compared with values obtained by applying well-known elastic theoretical methods used to assess stresses applied by tyres on bare soils. The corresponding results show that the increment of vertical stresses decreases as matric suction increases, and a good correlation between measurements and simulations of the increment on subsoil vertical stress.
Analysis of the bearing capacity of continuous flight auger piles in terms of their excavation energy and of rainfall data
Authors: Ferrari de Campos Darym J. , Camapum de Carvalho José , Gitirana Gilson F. N. , Cavalcante Andre L. B. , Ozelim Luan C. S. M.
Published: April 2021

Continuous flight auger piles (CFAs) are among the most common types of foundation executed in the tropical residual soil of Brasília, DF, Brazil. The bearing capacity of CFAs can be controlled according to the energy required to excavate each pile but is also influenced by seasonal conditions that affect the unsaturated soil profile. In the present article, a database of controlled execution of CFAs carried out at Brasília-DF was evaluated. The execution methodology enabled the full control of the drilling energy. Load tests were also performed and the pile bearing capacity was estimated by extrapolating the load-settlement curve using the van Der Veen method. As the site was excavated before the foundation was built, the morphology of the site was also considered in the analyses. Furthermore, by comparing the execution energies and climatological information, a relation between the moisture indexes and the execution energies was investigated. From these analyses, discussions regarding the relation between the bearing capacity of the piles tested and the rainfall regime they have been subjected to are presented. The changes observed in bearing capacity due to climatological effects may lead to economical savings and offer enhanced reliability in the design of CFAs.
The U.S. military culture system of values mirrored by professional lingo
Authors: Romanov Alexander , Stepanov Sergey , Poluboyarova Marina , Angaleva Mariya , Belaya Natalya
Published: April 2021

This research unveils the nature of relations among such phenomena as "ethnos", "culture" and "language". Vested with the function of axiological retranslation, mottoes of the U.S. Armed Forces services and branches make essential part of the military lingo as a semi-autonomous existential form of the national language. Clichéd formulas of the professional sublanguage official register explicitly reflect collective mindset, dominant values, behavioral patterns, and conceptosphere of America’s society military cluster. The authors arrive at the conclusion that military mottoes are typical of vocativity, brevity, metaphoricity, widespread use of Latinisms, stereotypogenicity, and appeal for professional ethos.
Principles of strategic management for the development of the road transportation system
Authors: Gavrilenko Natalia Gennadevna
Published: April 2021

Strategic development of freight road transport in the Russian Federation requires formation of reliance on fundamental economic theory, the absence of which, as of today, according to a number of well-known economists, is the main cause of emerging difficulties in formation and implementation of strategic documents in Russia. Such documents would include Transport strategy of the Russian Federation for the period up to 2030, and therefore, of special importance is the task of clarifying the key principles for strategic management of the development of the road transport system. The article reviews and substantiates the principles of: “consistency”, “digitalization”, “openness”, “established development trajectory”, “variety of development paths”, “hierarchy of management”, “increasing complexity of motivation”, “awareness” and “feedback”.
Diversity of economic development in Portuguese-speaking countries
Authors: Savelyev Mikhail , Kutyashova Elena , Savchenko Andrey , Koretsky Vladimir , Polyakov Yuri
Published: April 2021

The rates of growth and stability of economic development of the countries of the Portuguese world in the years 1870-2018 are investigated. The comparison has been carried out for 15 economic cycles, which are grouped into following historical periods: monarchical, dictatorial and democratic. The developed method for researching economic development policies makes it possible to quantitatively assess the historical fate of territories in terms of growth and risk. The indicators of the standard deviation of the growth rates of real gross domestic product were used as an indicator of sustainability. The features of progressive, regressive, conservative and aggressive policies of economic development are described. It is shown that during the entire studied period, only Spain which is beyond the Portuguese-speaking word demonstrated similarity in development with Portugal. Brazil's development trend deviated from the metropolis after 130 years of independence and 60 years of obvious institutional differences. African colonies in their turn immediately began to demonstrate a drastically different development policy. This proves that culture has a more significant and long-term impact on economic development than state and social institutions. The results obtained show that the Portuguese world has not formed a separate civilization with special and peculiar traits to be united with the common historical fate.
Modeling the coherence of the financial system and economy of Russia
Authors: Smirnov Valery V. , Semenov Vladislav L. , Zakharova Anna N. , Zimin Sergey B. , Mulendeeva Alena V.
Published: April 2021

The article assesses the coherence of the financial system and economy of Russia, and also reveals the uncertainties in interrelation between the flow of finance and economic activity. The work reveals the possibilities of ensuring preservation of the form and content of economic system in the process of creating and using monetary funds. An analysis of the actual change of pace in the growth rate of finances and economic activity was carried out to eliminate the uncertainty of interrelation between the flow of finance and economic activity. In the result of the analysis, it was revealed that financial and economic measures are resorted to in order to eliminate uncertainty, and thereby, to ensure the preservation of coherence of the financial system of the modern Russian economy. Financial measures include an increase in gold reserves and monetary base; economic measures include an increase in the production of crude oil and natural gas and petroleum (associated) gas, extraction and dressing of iron ores. As a result of modeling the dynamics of the financial and economic systems with application of the modified Cobb-Douglas formula it is revealed that the financial system actively follows the dynamics of the economic system and there is sufficient compensating reaction of the former.Coherence of the Russian financial system and economy determines the capability and ability to maintain the form and content of the Russian economy with the help of finance. Elimination of the uncertainty of interrelation between the flow of finance and economic activity is confirmed by active following of the Russian financial system in path of the economic system dynamics and compensating reaction of the financial system.
COVID-19: assessment and forecast of the development of the residential real estate market of the Russian Federation using the housing affordability factor model
Authors: Tretyachenko Tatyana , Pivovarova Galina , Sogomonyan Svetlana
Published: April 2021

The situation in the Russian real estate market can be significantly aggravated in the context of the crisis caused by the pandemic COVID-19. To understand how soon the Russian residential real estate market will be able to adapt to the new realities, it is necessary to give a forecast of the main trends that will occur in this sector in the post-viral era. The impact on the residential real estate market of the crisis caused by the widespread introduction of the quarantine regime and other restrictive measures in the framework of countering the pandemic of viral infection, the declaration of public health emergencies has not been investigated in the international and domestic literature. Since the current crisis is caused by the shock of demand and the shock of supply, which allows us to talk about it as a financial crisis with massive bankruptcy of both legal entities and individuals, the authors in their study relied on scientific works, the subject of which were the development of the real estate market in the context of the economic crisis. The main results of the study include: highlighting the characteristics of the residential real estate market that developed on the eve of the outbreak of the crisis; in conditions of shock period; its restoration and possible directions for the development of the residential real estate market in the near and medium term. In order to predict the situation in the domestic residential real estate market, a model of housing affordability ratio was applied (taking into account mortgage support). The findings of a study of the situation in the residential real estate market allowed the authors to propose a number of measures that need to be taken at the level of state authorities in the context of the "pandemic effect."
The Baikal region as a unified socio-ecological and economic system in the strategy of territorial development of the Russian Federation
Authors: Dugina Evdokia , Dorzhieva Elena , Bazarova Ouyna , Bulatova Nadezhda
Published: April 2021

The Baikal region, which includes 3 constituent entities in the territory of the Russian Federation - the Republic of Buryatia, the Irkutsk Region and the Trans-Baikal Territory - should be considered due to its location (in the territory of the Lake Baikal drainage basin) and from the point of view of the regional economy as a single socio-ecological and economic system, whose development should be aimed at preserving the unique ecosystem of the deepest lake on the planet. However, in the Territorial Development Strategy of the Russian Federation, the Baikal region is not included in the list of macroregions despite its compliance with the general principles of their formation. In our opinion, the Baikal region is united by a specific mission entrusted to its population - the need to preserve the unique Baikal ecosystem while ensuring a decent level and quality of life for people living in the Baikal natural territory. The article analyzes the need for a transition to an environmentally oriented innovation economy, which allows transforming the "Baikal factor" from a problem that hinders economic growth into a resource for territorial development.