bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of the composition of cement systems on the activity of modifying additives
Authors: Onoprienko N N , Salnickowa O N 
Published: October 2020

Abstract
Modifiers of cement systems with different compositions of functional groups of polymers were studied: carboxymethylcellulose, methylcellulose, polyvinyl alcohol, polyacrylamide. The results of studies of the influence of active ions on the viscosity of aqueous solutions of water-soluble polymers using viscometry methods are presented. The influence of the type and composition of functional groups of polymer additives on the resistance to calcium, sodium and potassium ions is analyzed. It is shown that in the presence of calcium, sodium or potassium ions in the liquid phase of cement solutions, it is possible to reduce the effectiveness of polymers as stabilizers of binding systems. The most resistant to electrolytes are polymers with dominated hydroxyl groups. The composition of functional groups of water-soluble polymers and the possibility of their interaction with various ions contained in cement, aggregate, filler, in the closing water, in the composition of soils have a decisive influence on the compatibility of the polymer and the binder, the properties of cement-polymer compositions. The principles of regulating the rheological and technological properties of cement-polymer compositions, deformations of dispersed systems by selecting the rational composition of the dispersed mixture, mineral and chemical additives are given. The regularities of compatibility of components of cement systems, mineral and chemical additives in order to increase the adhesion and strength characteristics of materials based on them in the development of compositions of masonry solutions, injection and other compositions for chemical fixing of soils, in individual housing construction, in order to carry out repair and restoration work to strengthen soil bases and stone structures are presented.
Processes of forming protective and decorative coatings on concrete at plasma treatment
Authors: Bondarenko N I , Bondarenko D O 
Published: October 2020

Abstract
The development and improvement of technologies for obtaining coatings on various composites using low-temperature plasma is very relevant today. The paper considers the possibility of using broken glass of colored container glasses and other sanitary construction ceramics to obtain protective and decorative coatings on concrete, the selection of the ratio of which will allow getting different tints of the melted layer. To expand the color and decorative characteristics of coatings, mixtures for powder and further compaction were developed. The results of research on plasma treatment of concrete with developed protective and decorative coatings based on broken glass of colored containers, special sanitary construction ceramics and alumina cement are presented. An organoleptic assessment of the quality of coatings after plasma treatment is given. The optimal fractional composition for obtaining protective and decorative coatings on concrete was identified and the optimal speed of plasma treatment of the front layer of the product was established. For practical use, the fraction of colored container glasses and sanitary construction ceramics 0.63-0.8 mm is recommended. By adjusting the speed of the plasma jet passing over the front surface of concrete, they can get a coating with various decorative and relief effects. It was found that at the plasma treatment speed of 10 mm/s a solid coating is formed, and at the plasma treatment speed of 25 mm/s a coating with a bumpy surface is formed.
Use of a supply ventilation system as an air curtain
Authors: Kireev V M , Alifanova A I , Ovsyannikov Yu G 
Published: October 2020

Abstract
Recently, for a number of reasons, retail and office premises on the first floors of the building, which have a separate entrance to the street, have gained wide popularity. These rooms must have supply ventilation to maintain the required microclimate parameters. The article proposes, in addition to fulfilling its main function, to use general exchange ventilation as an air curtain in these types of premises. Due to the supply of air above the doorway with certain parameters, in some cases, it is possible to abandon the thermal air curtain as a separate energy-intensive device. The implementation of this task is supposed to be carried out by organizing the necessary air exchange scheme, without increasing its required performance. The article presents the results of the study, which make it possible to assess the possibility of using the proposed technical solution for the most standard case. In particular, an adapted calculation of the air distribution grille is presented to fulfill the stated purpose.
Modifying additive for concrete based on shungite processing waste
Authors: Yestemessova A S , Altayeva Z N , Sarsenbayev B K , Budikova A M , Karshygayev R O 
Published: October 2020

Abstract
The paper is devoted to the study of waste processing of shungite rocks, which are formed in the process of mining and technological operations. However, the market of national modifying additives based on local raw materials is not developed at the appropriate level in the presence of a rich resource base of the mining industry. In this regard, it is of great interest to obtain additives based on shungite rock processing waste, which allow expanding the range of mineral additives and providing qualitatively new properties for concrete and reinforced concrete products and structures. Such technologies for the production of additives are isolated and not developed at the proper level due to insufficient knowledge of shungite rocks.
Analysis of the state of research on concrete and the market for modifying materials showed that the development of production of energy-efficient and environmentally friendly materials due to increasing regulatory requirements for them, as well as to environmental ecology and the obvious need to recycle industrial waste initiated the progressive development of concrete science. One of its latest achievements is modified concrete with special properties, which marked a new stage in the development of concrete. In its production technology, significant progress has been made in improving its chemical additives, special modifiers, as well as active and inactive fillers. In Kazakhstan, the main volume of modifying additives is imported from abroad, which significantly increases their cost, so their choice is limited.
This paper is devoted to the research of waste processing of shungite rocks as a modifying mineral additive of concrete. Its influence on the main indicators of concrete is investigated and the features of the processes that occur in the hardening silicate system “cement - dispersed shungite particles” and contribute to increasing the strength of concrete, as well as reducing the duration of its heat-and-water treatment are studied.
Using wastes of buckwheat processing as sorption materials for the removal of pollutants from aqueous media: a review
Authors: Shaikhiev I G , Sverguzova S V , Galimova R Z , Grechina A S 
Published: October 2020

Abstract
Based on data from various literature sources, information is given on the chemical composition of straw and husk of buckwheat grains. The information on buckwheat processing waste as a source for obtaining various valuable components is provided. Literature data on the use of ground buckwheat straw as a sorption material for the extraction of heavy metal ions and oil products from natural and sewage are presented. The possibility of increasing sorption characteristics by buckwheat straw treatment with various chemical reagents is shown. Determined that the husk of buckwheat grains contains cellulose and lignin most of all. Information is given on the use of the fruit shells of buckwheat grains as sorption materials for the removal of metal ions, oil and oil products from aqueous media. It was shown that to increase the sorption characteristics of these pollutants is possible by treating the sorption material with acidic chemical reagents and high-frequency low-pressure plasma. The parameters of acid treatment or plasma exposure are determined at which the highest adsorption indicators. Native straw and buckwheat husk are effective sorption materials for the removal of heavy metal ions and oil from aqueous media. It is possible to increase the sorption characteristics according to pollutants by a chemical or physical and chemical modification.
Analysis of power parameters of a rotary mill
Authors: Orekhova T N , Sheremet E O , Kachaev A E 
Published: October 2020

Abstract
The paper (publication) presents a description of the developed design of a rotary mill with a complex mechanical and acoustic effect on the dispersed material, as well as analytical studies of the parameters of energy consumption of a rotary mill, based on the main physical processes occurring in it. The research was carried out by mathematical and simulation modeling of technological processes in the grinding chamber of the mill, as well as on various technological paths of the unit. To determine the main parameters that make up the total power consumption of the unit, an approach was chosen to differentiate the processes by their physical nature and contribution to the formation of the total power consumption of the rotary mill.
The obtained results of mathematical modeling of processes occurring inside the technological paths of the unit allowed getting expressions for determining the main power costs of the unit depending on the characteristics of the unit design for each component of the total power required for effective operation of the unit at the required parameters of the dispersion of the finished product.
Features of setting and strength gain of the foam concrete massif
Authors: Savenkov A I , Gorbach P S 
Published: October 2020

Abstract
The paper presents a study of the regularities of the processes occurring in the matrix and aerated concrete mass at the initial time after laying and later, during the strength gain. The colloidal properties that appear in the foam concrete mix begin at the stage of mixing the components containing binder and aggregate particles, and are activated by the mixer blades. In this case, the mixture is transformed by mass transfer of the matrix material onto the foam grid and a new spatial reorientation of the bubbles under conditions of physical and mechanical effects on the thin-film structure of the foam. In technology, it should be taken into account that the processes occurring in the foam concrete mixture can be attributed to two opposite actions occurring simultaneously. First, in a freshly laid foam concrete mixture, as in any thermodynamically unstable system, sedimentation and coalescence of air pores begins, which is especially manifested at forcedly high water-solid ratios. This can lead, if the technology is not followed, to complete stratification of the mixture. Secondly, in the cement slurry, the setting and further formation of the cement stone occurs. A necessary technological condition for product quality is compliance with the optimal water-solid ratio of the mixture and ensuring the beginning of the setting of the foam concrete mass before its stratification.
It was also experimentally determined that an increase in the hardening duration of foamcement systems for more than 28 days is impractical, since it was revealed that an increase in the strength of foam concrete is similar to the same process in structural concrete. It is quite possible to achieve the strength required for foam concrete according to GOST 25485-89 within 28 days and even earlier due to the high technological discipline and the use of modern plasticizing additives.
Synthesis of a mineralizing agent for Portland cement from aluminum production waste
Authors: Endzhievskaya I G , Demina A V , Lavorenko A A 
Published: October 2020

Abstract
Priority directions in innovative technologies of the construction materials industry are the expansion of the use of mineral and chemical additives in the production of cements, as well as alternative raw materials and fuels in production processes. During the production of aluminum at the enterprise JSC RUSAL Krasnoyarsk, the method of electrolytic reduction of aluminum oxide or alumina dissolved in a cryolite-based melt generates fluorocarbon-containing (FCC) waste, which currently accumulates more than 16,000 tons per year. Due to the increased year-round generation of waste with a high content of carbon, fluorine and aluminum, it is urgent to develop technologies that will effectively use them as a new mineralizer product for the production of Portland cement clinker - calcium fluoride. This paper describes the thermal method of waste processing FCC for receipt of the mineralizing agent (fluorite). The disadvantage of FCC as a raw material is an increased concentration of alkali metals, whose oxides negatively affect the process of hydration of clinker minerals, and lead to the formation of efflorescence on products. To reduce their content, the finished fluorite was washed with water. Calcium fluoride as a mineralizing agent in the production of Portland cement, reduces the clinkerization temperature, increases the content of alite, changes the stability, polymorphism and reactivity of phases. The resulting fluorite with a high mass concentration of 73.9% CaF2 makes it possible to reduce the clinker formation temperature, which increases the energy efficiency of obtaining Portland cement. The technological process for removing alkaline components from the product will reduce the likelihood of destructive processes in concrete caused by the aggressive action of reactive silica aggregates and freezing and thawing processes.
Polymer composite material based on titanium hydride
Authors: Cherkashina N I , Popova E V , Pilavidou E O , Klopot E P 
Published: October 2020

Abstract
The article discusses the possibility of synthesizing highly filled polymer composites based on polystyrene and titanium hydride. The composites were prepared by solid-phase compaction at high specific pressure. For uniform distribution, titanium hydride was preliminarily milled in a jet-vortex mill. The particle size of titanium hydride after grinding is in the range from 0.1 to 107 μm. The modal particle diameter is 35.41 μm, and the specific surface area of the particles is 15279 cm2 / cm3. The titanium hydride content in the composites did not exceed 60 wt%. The article presents data on the density and microhardness of the obtained composites. It was found that the introduction of titanium hydride increases the physicomechanical characteristics of the composites. The Vickers microhardness of a pure polystyrene sample is 19.87 ± 0.20 HV, and a sample containing 60 wt% titanium hydride is 36.17 ± 0.78 HV (at a load of 200 g).
Heat-resistant structural composite material based on modified titanium hydride
Authors: Yastrebinsky R N , Karnauhov A A , Denisova L V , Pilavidou E O 
Published: October 2020

Abstract
The paper presents the results of studies of technological parameters of production, physical, mechanical, thermophysical properties and processes of gas formation during thermal heating of a composite material based on a modified fraction of titanium hydride and a Portland cement binder. The introduction of a plasticizing additive into the composite makes it possible to improve the technological and strength characteristics of the protection material. It has been shown that the decrease in the physical and mechanical characteristics of the material does not exceed 10 - 20%, which indicates its thermal stability in terms of the main performance indicators. The introduction of a boron additive does not significantly affect the physical and mechanical properties of the composite. It was found that the main gas evolution occurs during the drying of composites and practically ends after its completion. Reheating the cooled block to the initial heating temperature (300-350 °C) practically does not cause gas or water evolution, if during the cooling period the material had no contact with water.
Mechanochemical Production of Urea-citric Acid Copolymer
Authors: Miranda Eval O. , Silva Victor H. R. , Leão Mirtânia A. , Cabral-Albuquerque Elaine C. M. , Cunha Silvio , Fialho Rosana L. 
Published: October 2020

Abstract
Increasing non-biodegradable plastic consumption is a great factor that contributes to worldwide pollution and global warming. Mechanochemistry provides a clean, solvent-less, route for chemical reactions such as polymerization based on the absorption of mechanical energy. Urea polymers have several applications in industrial and medical area, such as paints, resins, plastic, wood glue, separating aliphatic hydrocarbons, coating, and pharmaceutical drugs. In this study, a copolymer of urea and citric acid was synthesized using a planetary ball mill as grinder with fixed reaction time and rotational speed, varying the number and material of the planetary ball mill sphere to find the effects of those two conditions in the yield percentage of the copolymer. The purified polymer was characterized by Infrared spectroscopy (FTIR) and Nuclear Magnetic Resonance – NMR. Results confirmed that polymeric material is formed by the reaction between citric acid and urea without any catalyzer using mechanochemistry. NMR results showed that the reaction occurred between urea and the acid groups at the ends of the chain, while the central COOH remained intact.
Relationship between cooling rate, microstructure evolution, and performance improvement of an Al–Cu alloy prepared using different methods
Authors: He Chen , Yu Wei , Li Yong , Wang Zhaodong , Wu Di , Xu Guangming 
Published: October 2020

Abstract
The relationship between the cooling rate and microstructure evolution and the performance improvement of an Al–4.5 wt% Cu alloy prepared using different casting methods was investigated. The microstructure evolution, solute element distribution, and mechanical properties of specimens prepared using different cooling rates were systematically investigated using multi-scale optical microscopy, scanning electron microscopy, transmission electron microscopy, tensile testing, and hardness testing. Upon increasing the cooling rate from 1.65 to 117.3 K s−1, the average grain size, secondary dendrite arm spacing, and width and area fraction of eutectic phases significantly decreased, and the density of the precipitated phase, super-saturation degree of solute elements, and mechanical properties improved. Through a combination of grain-boundary, solid-solution, and precipitation strengthening, the cooling rate indirectly affected the mechanical properties of the heat-treated alloy sheets. The Al−4.5 wt% Cu alloy prepared by twin-roll casting under a cooling rate of 117.3 K s−1 exhibited a strength between 145.33 and 321.79 MPa and an elongation of 11.65%, demonstrating its potential as a high-performance aluminium alloy.
The Iron Cage of Erasure: American Indian Sovereignty in Jill Lepore’s These Truths
Authors: Blackhawk Ned 
Published: October 2020

Abstract
This AHR Roundtable features four short essays on Jill Lepore’s widely read synthesis of American history, These Truths: A History of the United States (2018). Lepore’s framework insists that the “self-evident” truths of the nation’s founding were anything but. The driving force of her narrative is the struggle of those excluded from this magic circle—really, the majority of the country’s population—to extend those truths beyond their narrow core of elite white men. The four reviewers—Ned Blackhawk, Matt Garcia, Mary Beth Norton, and Paul Ortiz—appreciate the “shared sense of national destiny” that clearly informs Lepore book. At the same time, they chide her for what they regard as significant omissions. These critical essays invite further consideration of how best to write a fully inclusive (and therefore dramatically reconfigured) national narrative
Lepore’s America, “Our America”?
Authors: Garcia Matt 
Published: October 2020

Abstract
This AHR Roundtable features four short essays on Jill Lepore’s widely read synthesis of American history, These Truths: A History of the United States (2018). Lepore’s framework insists that the “self-evident” truths of the nation’s founding were anything but. The driving force of her narrative is the struggle of those excluded from this magic circle—really, the majority of the country’s population—to extend those truths beyond their narrow core of elite white men. The four reviewers—Ned Blackhawk, Matt Garcia, Mary Beth Norton, and Paul Ortiz—appreciate the “shared sense of national destiny” that clearly informs Lepore book. At the same time, they chide her for what they regard as significant omissions. These critical essays invite further consideration of how best to write a fully inclusive (and therefore dramatically reconfigured) national narrative
LiBis: an ultrasensitive alignment augmentation for low-input bisulfite sequencing
Authors: Yin Yue , Li Jia , Li Jin , Lee Minjung , Zhao Sibo , Guo Linlang , Li Jianfang , Zhang Mutian , Huang Yun , Li Xiao-Nan , Deng Zhenzhong , Sun Deqiang 
Published: October 2020

AbstractThe cell-free DNA (cfDNA) methylation profile in liquid biopsy has been utilized to diagnose early-stage disease and estimate therapy response. However, typical clinical procedures are capable of purifying only very small amounts of cfDNA. Whole-genome bisulfite sequencing (WGBS) is the gold standard for measuring DNA methylation; however, WGBS using small amounts of fragmented DNA introduces a critical challenge for data analysis, namely a low-mapping ratio. The resulting low sequencing depth and low coverage of CpG sites genome-wide is a bottleneck for the clinical application of cfDNA-based WGBS assays. We developed LiBis (Low-input Bisulfite Sequencing), a novel method for low-input WGBS data alignment. By dynamically clipping initially unmapped reads and remapping clipped fragments, we judiciously rescued those reads and uniquely aligned them to the genome. By substantially increasing the mapping ratio by up to 88%, LiBis dramatically improved the number of informative CpGs and the precision in quantifying the methylation status of individual CpG sites. LiBis significantly improved the cost efficiency of low-input WGBS experiments by dynamically removing contamination introduced by random priming. The high sensitivity and cost effectiveness afforded by LiBis for low-input samples will allow the discovery of genetic and epigenetic features suitable for downstream analysis and biomarker identification using liquid biopsy.
Chapter Three Didymus on Attic tragedy
Authors: Coward Thomas R P 
Published: October 2020

Abstract
This chapter examines Didymus’ studies on Greek tragedy, in particular on Sophocles and Ion of Chios. It demonstrates Didymus’ methods of exegesis and his use of other exegetical corpora. It explains the thinking behind some of his choices and preferences, including the mistakes. Furthermore, it examines the problems of identifying Didymean material where Didymus is not named.