bluuebunny/crossref_metadata_2025 huggingface dataset:
Alimentación, estilo de vida y participación: un estudio etnográfico de los grupos de consumo agroecológico en Castilla y León
Authors: Moro Gutiérrez Lourdes , Lamarque Muriel
Published: May 2020

Las prácticas alimentarias son manifestaciones complejas y multidimensionales, generadoras de pautas culturales que plantean cómo deben producirse y consumirse los alimentos, al mismo tiempo que determinan patrones de conducta y represen­taciones asociadas. En torno a la alimentación se conjugan muchas otras actividades además de las estrictamente nutricionales y que constituyen una parte importante del bienestar, tanto físico como psicocultural. Este estudio aporta una experiencia de tra­bajo etnográfico sobre los efectos y las implicaciones sociales que conlleva participar en grupos de consumo agroecológico. Pre­tendemos comprender los significados y las representaciones que motivan a las personas a formar parte de estas asociaciones y analizar sus repercusiones tanto individuales como colectivas. Asimismo, buscamos indagar acerca de los posibles beneficios so­ciales, psicológicos y económicos que aportan a sus miembros y el modo en que todo ello incide sobre la diferenciación social, el sentimiento de identidad común y la sociabilidad. La mirada antropológica aplicada a los grupos de consumo agroecológico per­mite profundizar en las experiencias subjetivas y construcciones colectivas de los participantes, accediendo a las motivaciones, prácticas y valores que enmarcan su pertenencia a dichas estructuras asociativas.
La dramatización de una ciudad. Significaciones rituales urbanas de la Semana Santa de Huelva
Authors: Mancha Castro José Carlos
Published: May 2020

Este artículo es una mirada sobre la Semana Santa de Huelva a partir de uno de sus significados más profundos como fiesta religiosa popular: la imagen de un drama ritual urbano en el que se expresan diferentes discursos y narrativas, donde se ritualiza la relación de los sujetos participantes y los grupos sociales entre sí, con el lugar habitado y con las instancias de poder político y religioso. Englobado en una investigación etnográfica de mayor amplitud, centramos aquí la mirada en uno de los dife­rentes significados productores de sentido para la comprensión de esta compleja fiesta religiosa popular. Analizamos la conforma­ción, estructura y temporalidad del drama ritual y proponemos una interpretación acerca del simbolismo contenido en los cortejos procesionales que se ponen en juego en el ceremonial público.
Behaviour of a high-performance self-compacting concrete (HPSCC) with ternary mixtures of nano- and microsilica in the presence of chlorides
Authors: Reyes E. , Massana J. , Alonso F. , León N. , Moragues A.
Published: May 2020

In this paper, the influence of additions of nanosilica (nSi) and microsilica (mSi) on the behav­iour of binary and ternary mixtures in chloride environments is studied. The main objective is to obtain high-performance self-compacting concrete (HPSCC) with a high durability which can meet specific demands in such aggressive environments. Ten blends were manufactured using Portland cement (CEM I 52.5 R) and additions of nSi and mSi in binary and ternary mixtures. The results of three tests frequently used to evaluate resistance to chloride penetration– electrical resistivity, migration and chloride diffusion –were studied and compared. Both binary and ternary mixtures presented significant improvements in chloride resistance, generally in proportion to the total content of the addition. In all the ternary mixtures, high resistivity is obtained, which indicates that such mixtures have a notably low chloride penetrability. Furthermore, these mixtures provided extremely low chloride diffusion coefficients even at small addition ratios.
Antecedents of Global Brands Preference Among Generation Y in Malaysia
Authors: Abdul-Talib Asmat Nizam , Yusof Mahjabin
Published: May 2020

Consumers in Asia are known for preferring global brands as opposed to the locally manufactured ones. The emergence of global brands in the marketplace has brought many benefits as well as many obstacles, especially for local marketers. This study explored the antecedents of global brands preference among Gen-Y in Malaysia, notably country-of-origin, quality, design, and advertising. Three hundred students of higher learning institutions in Malaysia were selected to take part in the study. Multiple regression analysis was used to analyze the data. It was found that the country-of-origin, quality, and design positively influence global brands preference among Gen-Y. However, advertising was found to influence preferences negatively. The findings could help local marketers develop and execute their marketing plan better and global marketers to improve their strategies and be more competitive. Marketers should focus on the above aspects in their marketing plan to capture the markets of Gen-Y in Malaysia and thus addressing their needs and wants better.
Inverted Grammar Classroom
Authors: Pudin Chelster Sherralyn Jeoffrey , Edward Eugenia Ida
Published: May 2020

Flipped learning is basically a pedagogical model that reverses classroom activities. Materials or contents are provided online (in learning management systems or other learning platforms) and students will study the material prior to the lesson. Therefore, classroom time can be used to engage in activities such as problem-solving, discussion, and analysis. This study is an extended study of a previous research which explored the effects of the flipped learning approach in a grammar classroom. For this study, the focus is shifted to the grammatical errors made by students in their video presentation during the flipped learning session. The analysis of the findings showed that students' grammar errors are mainly on missed formation errors, addition error, omission error, and lastly, improper ordering. The findings of this study give ESL practitioners a better insight into student errors and should lead to improved grammar usage in the classroom through blended learning.
Green Consumer Behaviour
Authors: Akhtar Muhammad Farooq , Mohd Suki Norazah
Published: May 2020

Environment preservation is a global concern. Textile industry disposes of chemicals which effects environment and human life (water borne diseases). United Nations develops 17 Sustainable Development Goals (UNSDG's) to protect environment. Five SDG's addressing textile industry namely good health and well-being, clean water and sanitation, responsible production and consumption, climate action and life below water. Role of textile industry to achieve SDG's is inevitable. Textile policy of Pakistan 2014-19 confirms that international buyer is concerned about the environment which evidently shows potential of green marketing in textile sector of Pakistan. Green marketing encourages environment friendly marketing practices (product, price, place, promotion). The objective of this study is to integrate the theory of planned behavior and technology acceptance model. Green consumer behavior of textile sector of Pakistan is conceptualized with this extended lens. This study enhances the body of knowledge by conceptualizing green consumer behavior of textile sector through extended model. Practically, this study remains beneficial for marketing professionals and researchers to understand green consumer behavior of textile sector. Success of green marketing is the success of society to curb environmental problems.
On the Application of Fractional Derivatives to the Study of Memristor Dynamics
Authors: Banchuin Rawid
Published: May 2020

In this chapter, the authors report their work on the application of fractional derivative to the study of the memristor dynamic where the effects of the parasitic fractional elements of the memristor have been studied. The fractional differential equations of the memristor and the memristor-based circuits under the effects of the parasitic fractional elements have been formulated and solved both analytically and numerically. Such effects of the parasitic fractional elements have been studied via the simulations based on the obtained solutions where many interesting results have been proposed in the work. For example, it has been found that the parasitic fractional elements cause both charge and flux decay of the memristor and the impasse point breaking of the phase portraits between flux and charge of the memristor-based circuits similarly to the conventional parasitic elements. The effects of the order and the nonlinearity of the parasitic fractional elements have also been reported.
Young Adult Use of Sexting
Authors: Riggs Rachel E. , Punyanunt-Carter Narissra M.
Published: May 2020

Along with many of the unintended consequences of recent technology, research regarding “sexting” is a little behind the times. For the purposes of this chapter, sexting is defined as the sending or receiving of explicit or sexually suggestive messages, images, or videos via cell phone, email, or social media. While early research approached sexting as dangerous, with implications for bullying, child pornography, and harassment, later research has progressed to paint it as more common and happening among consensual adults. This chapter attempts to explain how sexting is becoming a normalized part of young adult relationships.
Battling Against Demeaning and Abusive Selfie Sharing
Authors: Fehlbaum Amanda E. , Bowden Katelyn
Published: May 2020

Image-based sexual abuse is a growing issue among young adults, and challenges remain as to how to support those who have had intimate photos distributed without their consent. This chapter begins with an exploration of image-based sexual abuse, including motivations for perpetration. The focus then shifts to address how victims might transform their feelings of helplessness into empowerment through challenging victim blaming, legislative avenues, and digital justice. Recommendations and solutions focus on engaging in activism. Throughout the chapter are stories from activists who work with Battling Against Demeaning and Abusive Selfie Sharing (BADASS), a non-profit focused on education, legislation, and advocacy work.
Sexting at a Young Age
Authors: Chalfen Richard
Published: May 2020

This chapter applies a social psychological approach to contemporary dilemmas with personal photographs used in “sexting” by young people. Specifically, Urie Bronfenbrenner's (1917-2005) Ecological Systems Theory is used to examine a collection of agents and agencies attracted to sexting. The theory identifies five types of nested environmental systems responsible for human development namely microsystem, mesosystem, exosystem, macrosystem, and chronosystem. This chapter examines how an unexpected diverse collection of people now play roles in controlling sexting as a social and technological practice. These include parents, teachers, peers, school administrators, police, judges, lawyers, software developers, the ACLU, media and sports celebrities, social scientists, the news media, among several others. Specific attention is given to how these systems and roles interact as a result of sexting practices and the attention given to visual issues. The author seeks to offer a “larger picture” and offer a sense of where and how pieces of the visual, cultural, and social fit together.
Barriers in Women's Romantic Partner Search in the Digital Age
Authors: Adeyinka-Skold Sarah
Published: May 2020

What are women's experiences of searching for and making romantic connections in the digital age? Drawing on semi-structured interviews with 111 Asian, White, Black, and Latina, heterosexual, college-educated women between the ages of 25 and 33, the author finds that, regardless of race, women searching for romantic partners encounter cyberaggression and men who are intimidated by their educational background and/or career achievements. Women of color also experience cultural sexual racism, and Black women additionally contend with being excluded as potential romantic partners by Black and non-Black men. She argues that these experiences constitute barriers to relationship formation in the digital age. Furthermore, this research contributes to scholarship that explores the intersection of race, gender, and technology and its impact on individuals' lived experiences.
Culturally Responsive Teaching and Training for Pre-Service Special Educators in Higher Education
Authors: Williams York
Published: May 2020

In the field of public education, special education teacher preparation is one of the most critical areas of teacher preparation in higher education, given the mandate of FAPE under the IDEA. Additionally, teacher preparation programming that provides pre-service teachers with the knowledge, skills, and clinical experiences that can meet the learning-diverse needs of students is of paramount importance. However, teacher preparation programs often focus on meeting accreditation standards, job placement and service opportunities while leaving the teaching of diversity in special education as an add-on to be fulfilled by service departments, humanities courses, and/or social science electives. In order for universities and institutions of higher education to fulfill its mandate of teacher-training in special education, with a focus beyond the disability, they must adopt a curricula revision that includes culturally responsive teaching and diversity.
Building Capacity to Support Culturally Responsive Social-Emotional Learning Practices in Schools
Authors: Ferrell Natasha , Crosby-Cooper Tricia
Published: May 2020

Research has demonstrated the positive relationship between student social-emotional development and academic achievement and overall positive life outcomes. Evidence-based social-emotional practices such as direct instruction in core social-emotional learning (SEL) components, modeling, and reinforcement of appropriate SEL skills have been found to increase student social-emotional functioning, reduce maladaptive behavior and promote prosocial behavior. However, despite reports of positive outcomes based on school-based interventions, there remain questions regarding the appropriateness of strategies and practices for students from racially, culturally, or linguistically diverse backgrounds. In order to address the needs of the “whole child,” educators must view social SEL with a culturally responsive lens to ensure equitable treatment and development for all students.
Utilizing Culturally Responsive Teaching in an SEL Curriculum
Authors: Morgan Ronald D. , Rodriguez Sonia , Rakich Sladjana
Published: May 2020

Schools are increasing the use of social emotional learning (SEL) curriculum, especially at the elementary level. As this trend continues, it's important to examine the SEL curriculum and the competencies that define it. While there are similar definitions for explaining what's involved in SEL, most educators agree that it's basically the process through which students acquire and effectively apply the knowledge, attitudes, and skills necessary to understand and manage emotions, in order to help them make more responsible decisions. In this chapter, the detailed elements of SEL will be reviewed first, followed by an overview of the basic tenets of culturally responsive teaching. Additional cultural needs that today's elementary, middle, and high school students face will also be addressed in this chapter. The last part of the chapter will discuss the importance of merging SEL and culturally responsive teaching in co-existence in order to develop a stronger curriculum for creating equitable outcomes for diverse groups of students.
A Restorative Approach to Culturally Responsive Schools
Authors: Barnett Dori A.
Published: May 2020

Restorative practice is inspired by the restorative justice movement in the criminal justice system, which puts repairing harm and relationships over and above the need for dispensing blame and punishment. Restorative practice refers to a broad range of principles and processes with the aim of developing healthy relationships and building community. Schools report that whole school implementation of restorative practice can lead to positive outcomes including improved school climate, increased academic achievement, and reduced racial disparities in school discipline. This chapter will explore how a whole school approach to restorative practice can transform schools and classrooms and create an inclusive, safe, and culturally responsive school community.
When Worlds Collide
Authors: McDonald C. Peeper
Published: May 2020

This chapter will equip any person with culturally responsive practices to engage with a multiracial student or family. Relevant literature and research on the multiracial population will be provided, including multiracial identity development models and common microaggressions that often occur within this population. Using fictitious case examples, common culturally insensitive mistakes will be reviewed. Through these case examples and follow-up questions to support critical thinking, the reader will clearly see the culturally insensitive practices that often occur with the multiracial population and ways to change language, interactions, and even documentation to support cultural responsiveness and interventions. The conclusion of the chapter summarizes key points and reminders when working with the multiracial population and serves as a “call to action” for readers to act as agents of change in educational settings by supporting and advocating for inclusivity and research-based, culturally responsive practices.
Children of Same-Sex Couples
Authors: Perez Debra M.
Published: May 2020

As the United States becomes more accepting of sexual minority people, more opportunities have become available for same-sex couples to become parents. Blended families with a new stepparent, planned families via insemination, as well as adoption and fostering are changing what defines a family. As the definition of a family changes, so must the ways in which schools interact with each family type. The shared experiences of sexual minority parents and their children are explored, and recommendations for schools are made.
Improving the Efficiency of Slag Portland Cement by Reducing Shrinkage Deformations
Authors: Samchenko Svetlana V. , Zorin D.A.
Published: May 2020

The influence of the artificial additive introduced at the joint grinding of granulated slag, Portland cement clinker and gypsum on the Portland slag cement hydration, its compression strength at an early stage and shrinkage deformation is investigated. It was found that in the presence of sulfoferrite clinker there is an amorphization of cement stone structure with formation of stone with high density and strength in early setting. The open porosity of the hardened paste is reduced by 13 – 15 % in comparison with plain Portland slag cement. The samples strength increases by 1.55 - 1.78 times at grade stage, by 15.5 - 19.4 % in bending and by 6.4 - 11.2 % in compression.
High-Quality Cement-Mineral Suspensions Using Stone Crushing Waste
Authors: Belyakova E.A. , Moskvin R. , Yurova V.S.
Published: May 2020

The quality of concrete is determined by the physico-mechanical and rheological properties of the original components. Rheological properties depend on the amount and concentration of the rheological matrix. Cement-mineral matrices of modern high-quality concrete are rheologically active suspensions which allow to provide the necessary fluidity and mobility of the concrete mix, as well as the required strength of concrete. The multicomponent composition of the water-dispersed phase is represented by cement, stone flour and hyperplasticizer. The article presents the results of studies confirming the possibility of replacing finely ground quartz with other highly dispersed rocks, including stone-crushing waste. It was revealed that increasing in the concentration of the water-dispersed phase by 10% made it possible to reduce the water-solid ratio while maintaining the required mobility of the mixture, and in some cases improved the spreadability of the suspension by 3-13%. It was determined that the physicomechanical properties of reaction-powder concretes depend on the density and porosity of finely dispersed components to a greater degree.
Experience of Using Self-Compacting Concrete Mixes in Transport Construction
Authors: Pulyaev I. , Pulyaev S.
Published: May 2020

The creation of self-compacting concrete (SCC) is associated with the introduction of plasticizing additives based on polycarboxylate esters (PCE). The first patent for a group of substances proposed for use as superplasticizers for concrete, was declared in the early 80-ies of the last century in Japan. In the mid 90-ies superplasticizers based on esters of polycarboxylates began to be used in Europe. In Russia, the use of self-compacting concrete began much later, and in bridge and tunnel construction almost a few years ago. Currently, in the European Union, 70-80% of reinforced concrete structures are made or erected from self-compacting concrete mixtures, and concrete is commonly called self-compacting. In Russia, such concretes are sometimes called self-leveling. The volume of their use is still small.
The Method of Estimating the Durability of Structural Materials from the Effects of Cyclic Loads
Authors: Kuznetsov E.A. , Sysoev O.E. , Kyaw Phone Htet
Published: May 2020

The article deals with the technique of predicting the durability of structural materials under the influence of low-cycle loads at different loading trajectories in a two-dimensional stress space at a flat stress-strain state. The use of this technique significantly reduces the number of time-consuming and expensive experiments while maintaining the quality of the results. The technique is based on the method of processing acoustic emission signals when the acoustic signals are allocated with a fractal dimension of the attractor 1≤ D2att ≤6 on a steady-state cyclic creep that reflects the accumulation of hazardous defects in the structural material. To predict the durability at a certain type of stress-strain state, but at any form of a cycle of low-cycle loading by the proposed method, it is enough to have the results of experiments at the maximum intensity of stresses, the minimum intensity of stresses and the saw-tooth form of the cycle of stress intensity change.
Disperse-Reinforced Polystyrene Concrete Modified by Silica-Containing Additive
Authors: Pykin A.A. , Lukuttsova N.P. , Golovin S.N.
Published: May 2020

The composition of disperse-reinforced polystyrene concrete for the manufacture of small-pieces load-bearing structural insulating wall products is developed. Its properties and microstructure are studied. It is composed of Portland cement, granular foamed polystyrene, basalt fibre, water and silica-containing modifier obtained by mixing condensed silica, superplasticizer S-3 and an aqueous solution of sodium water glass. The developed disperse-reinforced polystyrene concrete modified by silica-containing additive is characterized by higher values of adhesive strength (0.231 MPa), class by bending tension strength (Btb4), class by compressive strength (B5), cracking resistance coefficient (0.77), grade by frost-resistance (F1150) with a slight increase in the average density and thermal conductivity coefficient. The increase of physical and mechanical properties and frost resistance of polystyrene concrete of the developed composition is achieved by compaction and hardening of cement stone, improving its adhesion to granular foamed polystyrene due to the synergistic effect of a silica-containing modifier acting as an adhesive and structure-forming additive, and basalt fibre as a disperse-reinforcing component.
Features of the Formation of Properties of Stone-Mastic Asphalt Concrete Based on a Warm Polymer Modified Binder
Authors: Shekhovtsova S.Yu.
Published: May 2020

Stone mastic asphalt concrete is one of the main types of asphalt concrete used for the construction of road surfaces. The quality, reliability and longevity of which depends on road safety of vehicles. To reduce the intensity of aging processes occurring at the stage of production and laying of asphalt concrete, "green" technologies are used, based on the use of physical and chemical processes that reduce the viscosity of bitumen to produce warm asphalt mixtures. This paper discusses the features of the formation of properties of crushed stone-mastic asphalt mixes SMA-15 based on polymer bitumen modified, compacted at lower temperatures, relative to traditional asphalt concrete. The influence of chemical additives of domestic and foreign production of DAD-TA and Cecabase RT 945 on the properties of modified binder and asphalt concrete was studied. It was established that they have a positive plasticizing effect on the modified bitumen binder in crushed stone-mastic asphalt concrete without a decrease in heat resistance and adhesive strength, which made it possible to compact asphalt concrete samples at low temperatures (up to 130°C) without negatively affecting the strength and deforming properties of asphalt concrete.
Influence of Thermally Processed Zeolite on Properties of Composite Gypsum Binder
Authors: Egorova A.D. , Emelianova Z.V. , Diyakonova M.N.
Published: May 2020

One effective way to improve the water resistance of gypsum binder is to add a hydraulic additive consisting of Portland cement and an active mineral additive regulating the formation of highly basic compounds. Various natural and artificial mineral substances are used as additives. It is known the effectiveness of fine-ground natural zeolites of the "Honguruu" (hongurin) deposit in the process of composite gypsum binders (CGB). There are also separate studies proving the increase in the activity of zeolites during their calcination at temperatures of 300-400 ° C. This paper presents the results of the study of the effect of the calcination temperature of hongurin on the properties of CGB. As a result of the studies, the optimal calcination temperature of hongurin - 180 ° C was determined. At the same time, the activity of hongurin increases, which provides significant growth of mechanical indicators of rock on the basis of CGB: the ultimate strength at compression of samples at the age of 28 days from compositions without plasticizer increased by 90% at addition of plasticizer in the amount of 1% - by 35%, and at 2% - by 57%. But with the use of calcined hongurin there is a slight decrease in the water resistance of the rock: in the optimal composition from 0,96 to 0,87, it is explained by the decrease in the activity of hongurin due to the reduction in the number of active groups, and the resulting new centers have a Lewis character.
Effect of Electron Beam and Heat Treatment on the Reactivity of Aggregates and Mineral Additives towards Alkali-Silica Reaction in Portland Cement Compositions
Authors: Brykov Aleksei B. , Mjakin S.V. , Sychov M.M.
Published: May 2020

Electron beam (EB) and heat treatment of silica-containing aggregates and mineral additives for Portland cement mortars is shown to affect their activity in alkali-silica reaction (ASR) damaging concrete structures. In the case of ordinary mortar based on the sand free of alkali-reactive inclusions, both heating to 900°C and EB processing result in a significant increase of reactivity growing with the absorbed dose in the range from 100 to 600 kGy and correlating with the increase in the content of acidic hydroxyl groups on the surface. For sand with reactive chalcedony inclusions, EB treatment results in the growth of their reactivity while heating provides its significant decrease. In case of mineral additives such as silica fume and metakaolin known as very effective ASR-inhibitors, similar processing leads to the increase of their activity in mitigation of ASR. The observed effect is promising for simulation of expansion processes caused by ASR and enhancement of concrete structure resistance to alkali destruction during exploration.
The Study of Heat and Mass-Exchange Processes during the Drying of Granulate of Hydrophobic Polymers
Authors: Geller Yu. A. , Shatskikh Yu. V. , Antanenkova I. S.
Published: May 2020

In this article, the drying characteristics were studied for granules of hydrophobic polymers, in particular, poly (ethylene terephthalate). To analyze the data, the modified quasi-stationary method was used. A modified quasi-stationary method has been proposed to describe drying kinetics of particulate materials dried in convective dryers with active hydrodynamic regimes. Parameters of reduced time and hydrodynamic intensity index were obtained for the generalized drying curve. Equations with refined parameters can be used to calculate the drying time and determine the temporal change in moisture content and material temperature.
Investigation of the Effect of Mechanical Activation of Powder Components on the Properties of Polyimide Composites
Authors: Cherkashina N.I. , Kuprieva O.V. , Kashibadze N.V.
Published: May 2020

This study presents the results of an analysis of the influence of joint mechanical activation of a polyimide matrix and tungsten (IV) oxide (WO2) on the mechanical properties of their composites. Mechanical activation of the powder components of the matrix and the filler is performed in a vortex jet mill. The ultimate tensile strength, tensile modulus and relative elongation at break of the composites are all investigated. When using mechanical activation, an increase in tensile strength of 9% is observed with a content of 30 wt.% WO2 filler and of 12% with a content of 70 wt.% WO2 filler compared to composites in which the joint mechanical activation of components is not used. Using scanning electron microscopy, it is shown that the use of mechanical activation by dispersing in a jet-vortex mill made it possible to achieve a uniform distribution of highly dispersed filler based on tungsten dioxide in a polyimide matrix.
Thermophysical Properties of Syntactic Foams Based on Polymethylphenylsiloxane Resin and Hollow Glass Microspheres
Authors: Mastalygina Elena E. , Smirnov K. , Chukhlanov V.Yu.
Published: May 2020

The syntactic foams based on polymethylphenylsiloxane resin filled by hollow glass microspheres were developed for using in different applications of construction industry. Thermophysical properties of the developed syntactic foams were analyzed in this work. According to the study results, with an increase of polymethylphenylsiloxane content in the syntactic foam, the thermal conductivity and the specific heat capacity increased. The coefficient of thermal linear expansion was dependent on the ratio of the components, reaching the lowest value for the composites with a minimum binder content.
Structure and Properties of Fibrous Materials Based on Poly(-3-Hydroxybutyrate)
Authors: Olkhov A.A. , Tyubaeva P.M. , Iordansky A.L.
Published: May 2020

The article studies the supramolecular structure of polymer matrices for sustained isolation of drugs based on ultrathin fibers of polyhydroxybutyrate obtained by electrospinning method. Dipyridamole was chosen as a model drug. The concentration of dipyridamole in the fibers ranged from 1 to 5%. The morphology of nonwoven fibrous materials was investigated by scanning electron microscopy, differential scanning calorimetry, electron paramagnetic resonance. It was shown that the addition of the dipyridamole leads to a change in the fiber geometry. Fibers based on polyhydroxybutyrate are characterized by non-equilibrium molecular structure. In the current work, it was found that the addition of dipyridamole causes extra crystallization processes and the molecular mobility in the amorphous regions of the polymer slows down
High-Performance Liquid Crystalline Polyesters: Influence of the Synthetic Pathway on the Thermal Properties
Authors: Deberdeev T.R. , Karimova L.K. , Akhmetshina A.I.
Published: May 2020

Liquid crystalline (LC) copolyesters derived from 4-hydroxybenzoic acid, terephthalic acid, and bisphenol A were synthesized under a variety of reaction conditions. Carboxylic groups in the raw materials were involved in either direct polycondensation or transesterification reactions. Protecting the carboxylic groups via methyl ester or phenyl ester formation was found to increase the yield and the molecular weight of the samples. It turned out that the maximal value of the degree of polymerization and, consequently, the highest heat resistance was observed for the samples prepared using phenyl esters of carboxylic acids.
Investigation of the Climatic Stability of Sealing Rubbers Used in the Technology of the North
Authors: Sokolova M.D. , Fedorova A.F. , Davydova M.L.
Published: May 2020

The present paper outlines the results of full-scale tests of climatic stability of rubbers based on BNKS-18 (butadiene-nitrile rubber) and Hydrin T6000 epichlorohydrin rubber containing low-volatile and non-toxic phenolic antioxidants. Samples are exposed in an open ground under natural conditions of exposure to climatic external factors of Yakutsk in the Republic of Sakha (Yakutia), as well as in deformed state (by 30%). Such indexes of the samples as conditional tensile strength, elongation at break are measured to determine the resistance of rubbers to aging after the first, third, sixth, ninth, twelfth and eighteenth months of exposing. The results of the study reveal the contribution of CO3 stabilizer in maintaining the stability of the physical and mechanical properties of BNKS-18: rubber containing CO3 has less property changes in the open air. Stafen stabilizer occurred more effective for the rubber based on Hydrin T6000: Over the entire period of full-scale exposure, rubber samples containing it demonstrated the smallest changes in the indicators of elastic-strength properties as compared to the industrial stabilizer 6РРD and other experimental stabilizers.
Regulation of Mechanical Properties of Advanced PCM Products with the Aid of Catalysts
Authors: Zaychenko I.V. , Bazheryanu V.V. , Kim A.G.
Published: May 2020

The article considers the problem of the effect of uneven curing caused by the temperature gradient across the thickness of the material on the anisotropy of the strength properties of polymer composite materials. The effect of catalysts on the curing of the epoxy binder EDT-69N, used for the manufacture of multilayer polymer composite materials, was studied. According to dielectric spectrometry, the accelerating effect of the selected compounds on the curing process of the EDT-69N epoxy binder during fiberglass molding has been proved. The possibility of controlling the curing process using catalysts to reduce the influence of the temperature gradient on the anisotropy of the strength properties of the matrix in the manufacture of polymer composite materials is shown.
Research of 3D Printing Modes of Feedstock for Metal Injection Molding
Authors: Korotchenko A.Yu. , Khilkov D.E. , Tverskoy M.V. , Khilkova A.A.
Published: May 2020

In this work, to reduce the cost of production of parts using injection molding metal technology (MIM technology), it is proposed to use additive technologies (AT) for the manufacture of green parts. The use of AT allows us to abandon expensive molds and expand the field of use of the MIM of technology in single and small-scale production. For manufacture of green parts, the technology of manufacturing fused filament (Fused Filament Fabrication – FFF) is offered. The original composition of the metal powder mix (feedstock) and the filament manufacturing modes for 3D printing have been developed for the FFF technology. The cost of filament is much lower than its analogs. The factors affecting the print quality of green part are considered. All factors are divided into two groups depending on the possibility of their change during printing. The research of the influence of the coefficient filament supply on the geometry of green parts during 3D printing is presented.
The Effect of Tungsten Nanoparticles on the Hardness of Sintered Sn-Cu-Co-W Alloys
Authors: Sokolov Evgeniy Georgiyevich , Ozolin Alexander Vitalyevich , Arefieva Svetlana Alexandrovna
Published: May 2020

The effect of tungsten nanoparticles and microparticles on the structure and hardness of sintered Sn–Cu–Co–W alloys has been studied. Tungsten powder of 19–24 μm sized particles was milled in a planetary-centrifugal mill, after which the size of particles was 25 nm to 20 μm. The milled and non-milled tungsten was then mixed with powders of tin, copper and cobalt. The specimens were compacted in moulds and sintered in vacuum at 820°C for 20 minutes. The structure of sintered materials was studied using X-ray diffraction analysis and scanning electron microscopy. Microhardness (HV0.01) of structural constituents and hardness of the materials were measured. It has been determined that it is alloys containing mechanically milled tungsten that have the highest hardness. The main factor influencing the rise of hardness is dispersion hardening with nanoparticles. A further factor is work hardening of tungsten microparticles during ball milling. The highest hardness of 109–111 HRB has been obtained in the Sn–Cu–Co–W alloy containing 23% wt. of milled tungsten, with the proportion of tin, copper and cobalt being 1/2.6/1.6.
The Regularities of Copper-Aluminum System Polymetallic Samples Manufacturing by the Additive Electron-Beam Technology
Authors: Kalashnikov K.N. , Osipovich Kseniya S. , Kalashnikova T.A.
Published: May 2020

The structure and composition of polymetallic materials samples obtained by electron-beam manufacturing from AMg5 aluminum alloy and M1 grade copper were investigated by optical and scanning electron microscopy. Mechanisms of defect formation in the structure of samples at different 3D printing parameters are determined. The features of gradient structures formation in the boundary zone at successive deposition of aluminum alloy and copper layers are investigated.
Welding of Cold-Resistant Micro-Alloed Steels 10HSNDA and 15HSNDA in the Atmosphere of Carbon Monoxide (II)
Authors: Ishkov Alexey V. , Ivanayskiy E.A. , Ivanov Valeriy I.
Published: May 2020

Micro-alloyed steels are widely used in the manufacture of critical welded structures operating under extreme conditions of the North. Microalloying of V, Nb and B is a simple and effective method of transferring known grades of structural steel and alloys to the category of increased and high strength, cold resistance, etc. The possibility of arc welding of steels grade 10CrSiNiAl and 15CrSiNiAl (10, 15ХСНДА in Russian), initially alloyed with trace amounts of niobium and vanadium to increase their cold resistance in carbon monoxide is considered. It is established that the use of the specified reducing atmosphere prevents the oxidation of the weld metal. The thermodynamic substantiation of the chemical reactions of microalloying elements proceeding in the weld pool, leading to the preservation of the steel composition, is presented. The chemical and metallographic analysis of welds was performed. The efficiency of using low-cost CO, or its mixtures with CO2, as substitutes for expensive argon and helium, when welding micro alloyed steels is shown.
Density and Surface Tension of Fe-Cu Melts
Authors: Vyukhin Vladimir V. , Chikova O.A. , Shmakova Ksenya Yu.
Published: May 2020

Fe-Cu alloys are used as structural materials for manufacture of large machine parts subjected to shock loads. Fe-Cu alloys have a higher corrosion resistance in a humid atmosphere and in salt solutions than cast steel. Fe-Cu alloys have high enough damping characteristics. Upon cooling the Fe-Cu melts is stratified into two phases before crystallization which in field of gravity are separated by density. It is possible to suppress delamination and obtain a material with structure of a “frozen emulsion” by heating melt to the temperature T* determined for each composition by a specific way. In this paper, we studied surface tension of liquid alloys of Fe-1wt.% Cu, Fe-20wt.% Cu, and Fe-30wt.%Cu in order to determine the temperature T*. For the melt of Fe-20wt.% Cu value T*=1670°C is highest. It is confirmed by results of measuring temperature dependence of surface tension. Temperature dependence of the surface tension Fe-Cu melts is characterized by a positive value of the temperature coefficient of surface tension dσ/dT which is abnormal for metal melts. Experimental data on the density, the surface tension of Fe-Cu liquid alloys have of independent metrological importance for practical foundry.
Influence of the Salt Bath Deoxidation Degree on Change in Hard Alloys Properties during Heat Treatment
Authors: Bogoduhov S.I. , Kozik E.S. , Shvidenko E.B.
Published: May 2020

Performance characteristics of hard-alloy tools are largely depends on the structure. The hard-alloy tool structure can be influenced by various factors. The main factors influencing the structure and properties of hard alloys at heat treatment are ВаCl2 salt bath deoxidation degree, heating temperature, holding time, rate of cooling and cooling medium, temperatures and holding time. Oxidation at temperatures more than 500-600оС and relatively low thermal conductivity of λ = 27.214 W/(m×K) are characteristic for hard alloys under heating.In this regard, it became necessary to study the salt baths deoxidation processes occurred in the course of heat treatment. Insufficient study of hard alloy heat treatment processes is associated with peculiarity of their structure and large assortment, difficulty of setting heat treatment modes.Research of hard alloy sample heating with the subsequent air cooling (normalization) was carried out in a salt baths in thermal area of tool shop.X-ray diffraction analysis was performed by Williamson-Hall method. In our experiments, coherent scattering regions size and WC phase micro-distortions magnitude were defined using MD-10 microdiffractometer. It was found out that phase structure of hard alloys is not change as a result of heat treatment. There are only reflections from carbide phase planes in the diffraction pattern. A quantitative analysis of diffraction reflection broadening using Williamson-Hall method showed that size of the coherent scattering regions for VK8 and T14K8 hard alloys subjected to hardening procedure is more than for sintered alloys.Relevance of the study is due to the fact that heat treatment involved heating in salt baths can be a promising method of improving mechanical and operational properties of hard alloys. This approach ensures necessary strength and performance characteristics of hard alloys without significant economic expenses.The purpose of this paper is to define effect of ВаCl2 salt bath deoxidation degree on physical and mechanical properties of VK8 and T14K8 hard alloys.
The Assessment of the Possibility of Smelting a Cast Alloy for the Manufacture of Components and Parts of Arctic Technical Equipment Using Ore from the "Verkhnyaya Amga" Ore Occurrence
Authors: Danilov A.D. , Stepanova Ksenia V. , Petrov P.P.
Published: May 2020

The research assesses the possibilities of using local minerals to create foundry alloys that are used in conditions of low temperature. The mineral-geochemical composition of iron ore from Verkhnyaya Amga ore occurrences in the Aldan region of the Sakha Republic (Yakutia) was studied in detail. The expedience of using iron ores from this ore occurrence to develop new cold-resistant and high-strength steels was analyzed. The chemical composition and microstructure of the cast alloys were studied. The ore contains oxides of alkaline earth metals: MgO; CaO; Sr0 and BaO, the total content of which is 4.2%, that contributes to the process of deoxidation of the melt during its cooling, and the deoxidation product in the form of oxides and other chemical compounds based on Ca, Sr and Ba floats into slag. During crystallization, the melt is cleaned of detrimental impurities, non-metallic inclusions, gases, pores, etc. Alloy is smelted from enriched ore, samples for static tension and toughness are made in order to study the physicomechanical properties. Microstructure of the obtained alloy and structural steel subjected to static tension at an external load of 0.8 yield strength (σ = 0,8 σт) was investigated. Mechanical properties and dynamic characteristics were measured. Analogues for comparing the strength and plastic properties were given.
Protective Coating Based on Organic Silicon Polymer of Ladder Structure Nanostructured with Alkoxysilane
Authors: Chukhlanov V.Yu. , Selivanov O.G. , Chukhlanova N.V.
Published: May 2020

New materials based on oligooxidridsilmethylensiloxysilane nanostructured with ethyl ester of orthosilicic acid – tetraethoxysilane have been studied in the research. Tetraethoxysilane introduction into the composition is supposed to cause its decomposition up to nanoparticles of silicon oxide. The alkoxysilane hydrolytic destruction kinetics and the impact of the composition and nature of the polymer composition components on the physical properties have been studied. Atomic force microscopy was used to study the structurization kinetics of the polymer composition. The composition hydrophobicity was determined by the edge wetting angle. To study the adhesion characteristics of the obtained material, the method of disc separation from the substrate has been used. The relative rigidity has been determined by a pendulum device M3. Atomic force microscopy revealed the presence of nanoscale neoplasms (at average of one hundred twenty per one square micrometer) in diameter from two to five nanometers in the surface structure of the composition, modified with tetraethoxysilane. Herewith the physical properties of the material change: rigidity increases, the edge angle of wetting increases as well. The studied nanostructured compositions can also be applied. For example – they can be used as a protective coating with a set of special properties, such as high hydrophobicity.
Intumescent Type Fire Retardant Epoxy Coating
Authors: Pestereva L. , Shakirov N. , Shakirova Оlga G.
Published: May 2020

This article discusses one of the methods of fire protection, namely, the coating of metal structures with fire retardant paints. Intumescent coatings are currently the most widely used. Fire retardant coatings based on epoxy paints have high performance characteristics and are promising. As the foaming component, the system of ammonium polyphosphate - pentaerythritol - melamine (in a ratio of 2: 1: 1) was selected. The fire retardant properties of the developed material were investigated. Coatings on the base of the developed fire retardant paint allow us to increase own level of fire resistance of metal constructions up to three (90 minutes).
Elemental Distribution of Gas-Thermal Coatings with W and Ta Modifiers
Authors: Lebedev Dmitry I.
Published: May 2020

Currently, the technology of arc metallization according to technical and economic indicators is a promising way to restore worn parts of equipment. In the coating process the cored wire is melted by an electric arc, and molten particles are accelerated towards the surface parts with high temperature gas flow. On the subsequent formation of strengthening coatings are significantly influenced the technological modes of electric arc metallization. As practice shows, the coatings obtained by electric arc metallization are characterized by a heterogeneous layered structure. The structure of powder coatings, the distribution, composition and properties of the phases affect on the wear resistance, hardness and strength of the machined surface of machine parts and mechanisms. It is therefore necessary a detailed study of the structure of wear-resistant coatings taking into account technological properties of cored wire, and process heating of the particles by arc spraying. In this work the X-ray microanalysis of the elements of the structure of wear-resistant coatings obtained from cored wire with a refractory additives were conducted. The results of the study will be useful for the improvement technology of electric-arc metallization cored wires.