bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of Psychological Distress among the General Public in Saudi Arabia during the Coronavirus Disease-19 Pandemic
Authors: Almanasef Mona , Almaghaslah Dalia
Published: August 2021

Background: COVID 19 and its preventative measures have disrupted people's day-to-day lives and jobs and consequently had an impact on their health and wellbeing. Studies have revealed high levels of depression, anxiety and sleep disorders. The main aim of this study was to determine the prevalence of psychological distress among the general public during the COVID-19 pandemic. In addition, it aimed to determine the characteristics of highly susceptible population.  
Methods: A prospective cross-sectional study using an online self-administered questionnaire gathering sociodemographic information and using the Kessler scale, which measures psychological distress. A total of 1,058 people agreed to participate in the study and completed the questionnaire.  
Results: The study findings showed that 48.6% (n=514) of the study’s respondents were psychologically distressed, i.e. either in the high or very high distress category. Significantly higher ratings of psychological distress were observed among female participants, younger adults, those who self-reported poor health status, single persons, students, individuals with caring responsibilities and those who have no access to a private outdoor space. This distress was also found among those who have been in close or indirect contact with an individual with confirmed COVID-19 infection, P< 0.05.
Conclusion: Psychological distress has been widely prevalent among the general public in Saudi Arabia during the COVID-19 pandemic. The Saudi government and the health authorities should pay special attention to the highly susceptible population and implement effective strategies to preserve and improve the mental health and wellbeing of these individuals.
Occurrence of the insectivores and rodents in the Samarskaya Luka (European Russia)
Authors: Kirillova Nadezhda , Kirillov Alexander , Vekhnik Victoria , Klenina Anastasia
Published: August 2021

In this paper, we present our dataset containing up-to-date information about occurrences of small mammals (Erinaceomorpha, Soricomorpha and Rodentia) on the territory of Samarskaya Luka. It is a bend of the Volga River in the southern part of the forest-steppe zone of the Russian Plain (European Russia). This unique territory is surrounded on almost all sides by water. The dataset summarises small mammal occurrences noted in long-term studies in Samarskaya Luka from 2000 to 2020. A major part of the dataset was obtained during our helminthological study of small mammals. Besides, some data were attained when studying the ecology of tree-dwelling rodents. Our studies of small mammals were conducted by trap lines and direct observations in the wild. The dataset includes 8147 records of erinaceomorphs, soricomorphs and rodents of 26 species (of total 28) belonging to three orders, nine families and 21 genera. It is based on the research of the staff of the Institute of Ecology of the Volga River Basin of the Russian Academy of Sciences and the Zhiguli State Nature Reserve. The distribution of erinaceomorphs, soricomorphs and rodents in Samarskaya Luka has not been completely studied and further investigation may well discover new small mammal habitats.

Our dataset contains new information on occurrences of erinaceomorphs, soricomorphs and rodents in Samarskaya Luka (European Russia). All occurrence records of 26 mammal species with georeferencing are published in GBIF for the first time. The occurrence data are stored in our field journals and we would like to make them available to all researchers.
Pars Plana Lensectomy, Pars Plana Vitrectomy, and Silicone Oil Tamponade as Initial Management of Cataract and Combined Traction/Rhegmatogenous Retinal Detachment Involving the Macula Associated With Severe Proliferative Diabetic Retinopathy
Authors: Douglas Mark J. , Scott Ingrid U. , Flynn Harry W.
Published: August 2021

BACKGROUND AND OBJECTIVES:

To evaluate visual acuity and anatomic outcomes, and complications, following pars plana lensectomy, pars plana vitrectomy, and silicone oil tamponade (PPL/PPV/SO) in the initial management of cataract and combined traction/rhegmatogenous retinal detachment involving the macula associated with severe proliferative diabetic retinopathy (PDR).

PATIENTS AND METHODS:

Retrospective, noncomparative, consecutive case series including all patients who underwent PPL/PPV/SO for the initial management of cataract and traction/rhegmatogenous retinal detachment involving the macula associated with severe PDR at Bascom Palmer Eye Institute between 1989 and 2000. Main outcome measures included visual acuity and rates of retinal reattachment and reoperation.

RESULTS:

The study included 22 eyes of 22 patients. The mean follow-up was 15.2 months. Preoperatively, 13 of 22 (59%) fellow (non-study) eyes had vision of light perception or worse, and 7 (32%) had vision of no light perception. The number of study eyes with a best-corrected vision of 20/400 or better increased from 5 (23%) preoperatively to 12 (55%) at 6 months (
P
< .05) and 15 (68%) at final follow-up (
P
< .05). The macula was attached at final follow-up in 20 (91%) eyes. In 14 (64%) eyes, silicone oil was removed at a mean of 8.4 months following retinal detachment repair; postoperative vision was 20/400 or better in 11 (79%) of these eyes at 6 months and 13 (93%) at final follow-up. In contrast, only 1 of 8 (13%) eyes with retained silicone oil achieved a postoperative vision of 20/400 or better (
P
< .05).

CONCLUSIONS:

Initial management with PPL/PPV/SO can achieve favorable anatomic and visual outcomes in selected patients with cataract and traction/rhegmatogenous retinal detachment involving the macula associated with severe PDR. This surgical approach should be especially considered in patients with traction/rhegmatogenous retinal detachment involving the macula in one eye and poor vision in the fellow eye.

[Ophthalmic Surg Lasers Imaging 2003;34:270–278.]
Vertical Conjunctival Bridge Flaps in Pterygium Surgery
Authors: Kaya Murat , Tunç Murat
Published: August 2021

BACKGROUND AND OBJECTIVE:

To evaluate the recurrence rates and clinical outcome following pterygium surgery using a vertical conjunctival bridge flap technique.

PATIENTS AND METHODS:

The study included 500 patients operated on for primary or recurrent pterygium during 6 years (between 1994 and 2000). Following receipt of informed consent, the patients were randomly distributed into two treatment groups: 250 patients were operated on using a vertical conjunctival bridge flap technique (Group 1) and the remaining 250 patients were operated on using a bare sclera technique (Group 2). Demographic characteristics of the patients were compared by analysis of variance. The mean follow-up period was 16 months, with a minimum of 6 months. The intraoperative and postoperative complications and recurrence rates were compared for each group.

RESULTS:

There was no statistically significant difference in age and gender distribution of the patients between the two groups (
P
> .05). The most common intraoperative complication was a broken or irregular flap, which was seen in 6 of 250 cases (2%) in the vertical conjunctival bridge flap group. The recurrence rate was 2% in the vertical conjunctival bridge flap group compared with 40% in the bare sclera group (
P
< .01).

CONCLUSION:

The vertical conjunctival bridge flap technique is a safe and effective method in pterygium surgery and offers low recurrence rates.

[Ophthalmic Surg Lasers Imaging 2003;34:279–283.]
Mid-Term Follow-up of Nd:YAG Laser Iridotomy in Asian Eyes
Authors: Hsiao Ching-Hsi , Hsu Ching-Tarng , Shen Su-Chin , Chen Henry S. L.
Published: August 2021

BACKGROUND AND OBJECTIVE:

To assess the long-term results of Nd:YAG laser iridotomy in the treatment of patients with primary angle-closure glaucoma and occludable angles to evaluate the risk–benefit ratio and the role of gonioscopy in predicting the outcome after Nd:YAG laser iridotomy.

PATIENTS AND METHODS:

The records of 138 consecutive patients (231 eyes) who underwent Nd:YAG laser iridotomy in one hospital during 3 years (from 1989 to 1991) were reviewed. The mean follow-up period was 51 months.

RESULTS:

Of all eyes, 25.1% were treated for chronic angle-closure glaucoma and 10.8% were treated for acute angle-closure glaucoma; most eyes (64.1%) underwent prophylactic iridotomy for occludable angles. Decreased intraocular pressure (IOP) was noted in most eyes after Nd:YAG laser iridotomy; only 10 eyes required further filtration surgery. Visual acuity was unchanged or improved in 97.9% of all eyes at the 6-month visit. Cataract progression was primarily responsible for those eyes with decreased acuity. Ninety-seven percent of eyes had quantitatively wider angles after laser treatment; 8 of 14 eyes with peripheral anterior synechiae of more than 270° underwent further surgery to control IOP. Transient elevated IOP and iris bleeding occurred in 23.5% and 12.2% of the eyes, respectively; other complications were rare.

CONCLUSION:

Nd:YAG laser iridotomy is a safe and effective procedure for the treatment and prevention of angle-closure glaucoma. Gonioscopy is useful to predict the outcome after Nd:YAG laser iridotomy.

[Ophthalmic Surg Lasers Imaging 2003;34:291–298.]
Photodynamic Therapy With Verteporfin for Subretinal Neovascularization Secondary to Bilateral Idiopathic Acquired Juxtafoveolar Telangiectasis
Authors: Hershberger Vrinda S. , Hutchins Robert K. , Laber Patrick W.
Published: August 2021

The clinical course of a patient treated with multiple sessions of photodynamic therapy (PDT) with verteporfin for subretinal neovascularization secondary to bilateral idiopathic acquired juxtafoveolar telangiectasis is described. The patient presented with subfoveal subretinal neovascularization in one eye secondary to bilateral idiopathic acquired juxtafoveolar telangiectasis. The visual acuity improved from 5/40 to 20/60 and fluorescein angiography documented near-complete closure of the subretinal neovascularization within 2 weeks following the initial session of PDT. The visual acuity decreased to 20/200 and fluorescein angiography documented reperfusion of the neovascular membrane 6 weeks later. Four additional sessions of PDT were administered during the next 13 months with similar results. This case indicates that PDT for subretinal neovascularization due to bilateral idiopathic acquired juxtafoveolar telangiectasis may achieve partial short-term neovascular membrane closure and improvement in visual acuity.
[Ophthalmic Surg Lasers Imaging 2003;34:318–320.]
Urban water resource management: experience from the revival of Rajokri lake in Delhi
Authors: Srivastava Ankit ,   Delhi Jal Board, Government of the National Capital Territory of Delhi, New Delhi, India, Prathna T.C. ,   Department of Irrigation and Flood Control, Government of the National Capital Territory of Delhi, New Delhi, India
Published: August 2021

Water bodies are critical in maintaining and sustaining ecosystems. However, urban water bodies are often ignored during development projects, and comprehensive plans for their revival and rejuvenation are not seen as priorities. This paper describes the rejuvenation project for a dry water body at Rajokri, Delhi, India. A "scientific wetland with active biodigester" (SWAB) system was developed to treat domestic wastewater, which was then used to fill the lake. The SWAB effectively removed about 89% removal of oil and grease, 86% biological oxygen demand (BOD), 85% chemical oxygen demand (COD) and 86% of total suspended solids (TSS) when the respective inlet concentrations were 18 ± 1.14 mg/L, 124 ± 2.9 mg/L, 480 ± 11.9 mg/L and 116 ± 1.82 from the raw wastewater. The SWAB system provides completely natural treatment with zero electrical consumption. The revival of the water body using a decentralized wastewater treatment system has immensely helped in management of urban wastewater, ground water recharge and enhanced ecosystem and biodiversity values. The project demonstrates the integration of socio-cultural, societal, ecological, ecosystem and technological aspects for the revival of the lake.
Hydrological response to land use and land cover changes in a tropical West African catchment (Couffo, Benin)
Authors: Togbévi Quentin Fiacre ,   Laboratory of Hydraulics and Water Management, National Water Institute, University of Abomey-Calavi, Benin, Sintondji Luc Ollivier
Published: August 2021

This study evaluated the impact of land use and land cover changes on the water balance of the Couffo catchment (Benin) using the Soil and Water Assessment Tool (SWAT). To that end, soil, land uses, hydro-meteorological data including rainfall, temperatures (maximum and minimum), wind speed, solar radiation, relative humidity and discharge data were used as main inputs. To assess the impact of land uses on the catchment water balance, three different land uses (2000, 2006 and 2011) were used. Results showed that from 2000 to 2011, croplands and fallows increased by 34% while the shrub and grass savannahs decreased respectively by 34 and 24%. In addition, agroforestry and gallery forest decreased by 63% and 58% respectively while a rapid increase in settlement. The study outcome suggested that the SWAT provided satisfactory results for discharge with R2, NSE, KGE and absolute percent of bias (absPBIAS) ranged between (0.7–0.9), (0.6–0.9). (0.6–0.9) and (5.3–34) respectively. Moreover, the evaluation of land use and land cover changes on the catchment water balance resulted in an increase in annual surface water and water yield, while the groundwater and actual evapotranspiration (ETa) have decreased. Findings of this study may be a great contribution to water resource management in the Couffo catchment. This may contribute to better allocate water for the actual catchment population demand without dampening those of the future generation.
Soil biostabilisation and interaction with compaction processes for earthen engineering structures production
Authors: Bernat-Maso E. , Gil L. , Lis M.J. , Teneva E.
Published: August 2021

Interaction between microbially induced calcium carbonate precipitation (MICP) and compaction procedures to stabilise raw soil materials has been studied with the aim of producing earthen engineering structures. Initial tests to optimise MICP in aqueous medium and in selected soils were performed. MICP and compaction were finally applied to assess medium-size elements. The main result was that sandy soils should be compacted before irrigation treatment to close the existing voids and prevent bacterial sweeping, whereas clayey soils should be compacted after irrigation treatment to avoid the plugging effect. MICP improved small sand soil compressive strength by up to 32% over the value reached by compaction alone. However, MICP had no positive effect on coarse soils and soils with an optimum particle size distribution: MICP treatment was not able to fill large connected voids in the first case and it caused little void generation due to bacteria sporulation in the second.
‘O corpo como residência do Espírito Santo’
Authors: Amstel Narayana Astra Van , Quitzau Evelise Amgarten , Moraes e Silva Marcelo
Published: August 2021

Benjamin Franklin foi um pensador americano que se tornou figura emblemática do imaginário estadunidense. Neste artigo, apresentam-se suas contribuições relativas à educação do corpo. Para se alcançar o intento, realizou-se uma pesquisa, tendo-se como fontes os escritos de Franklin que abordaram prescrições em relação à dieta e exercícios físicos. Demonstrou-se, pela análise das fontes, que uma moral de cunho religioso moldou os cuidados do corpo, apresentando elementos de quantificação, individualização, treinamento e moderação dos hábitos, com ênfase no papel da natação como atividade útil e saudável. Concluiu-se que uma moral protestante influenciou a visão de Franklin em relação à educação do corpo, por meio do utilitarismo vinculado ao ascetismo como estilo de vida.
Igreja, Estado e educação
Authors: Bilhão Isabel Aparecida , Klafke Álvaro Antônio
Published: August 2021

O artigo analisa o processo de constituição do Movimento de Educação de Base – MEB –, refletindo sobre a dinâmica das relações entre Igreja e Estado no Brasil, em um momento em que a educação no meio rural era disputada por diversos grupos sociais. Tem por objetivo compreender como, no interior de um Estado oficialmente laico, pôde ser firmado e justificado um convênio no qual o governo federal brasileiro financiou um movimento proposto e coordenado pela Igreja Católica. Embasando-se teoricamente nas noções de grupos de elite e influência, investiga as aproximações entre os agentes governamentais e religiosos envolvidos na consecução do acordo. Finalmente, analisa o decreto de formalização do convênio, relacionando alguns de seus pontos principais com o processo antecedente.
A trajetória histórica das leis e diretrizes curriculares nacionais para a área de formação em Educação Física
Authors: Metzner Andreia Cristina , Drigo Alexandre Janotta
Published: August 2021

O artigo objetivou contextualizar, historicamente, as principais leis e diretrizes que subsidiaram os cursos de formação de professores, sendo o foco principal a formação em educação física. Este estudo caracterizou-se como pesquisa documental. As fontes utilizadas foram leis e diretrizes que permeiam a formação em educação física, tendo como ponto de partida a década de 1930. Nota-se que os cursos de licenciatura estiveram presentes desde as primeiras formações em educação física existentes no Brasil. No entanto, as especificidades da formação de professores não estavam definidas de maneira substancial até as mudanças ocorridas pelas DCN de 2004.
Música, ginástica e dança no ensino secundário no Brasil do século XIX
Authors: Garcia Gilberto Vieira , Silva Gustavo da Motta
Published: August 2021

O artigo pretende analisar as relações entre o ensino de música, de ginástica e de dança no contexto do ensino secundário, no Rio de Janeiro do século XIX. Para tanto, as análises centraram-se em torno do Imperial Colégio Pedro II, pela sua idealização como instituição modelar para o ensino secundário no país. A concepção das ‘Belas Artes’ que perdurou até o fim do oitocentos, integrando também a música, a ginástica e a dança, será uma base fundamental para as discussões desenvolvidas ao longo do texto. A categoria analítica ‘relação de vizinhança’, definida por André Chervel dentro do estudo da história das disciplinas escolares, foi relevante para o desenvolvimento dessas articulações, sobretudo, para se refletir sobre a importância dessas matérias no currículo escolar.
Saber profissional do professor que ensina matemática
Authors: Valente Wagner Rodrigues , Bertini Luciane de Fatima , Morais Rosilda dos Santos
Published: August 2021

Este artigo tem por finalidade elaborar uma sistematização das discussões realizadas, a partir do estudo de uma das referências teórico-metodológicas constituintes de um projeto coletivo de pesquisa. Interrogamos: ‘Que contribuições a análise desse estudo dá à pesquisa histórica sobre o saber profissional do professor que ensina matemática?’ Foram consideradas quatro categorias de análise no âmbito das discussões realizadas sobre o referencial: relações passado-presente; papel dos experts na elaboração de saberes; relações entre campo disciplinar e campo profissional; articulações entre profissionalização/saberes/formação docente. O resultado aponta para um alargamento do próprio referencial analisado possibilitando melhor conformação do objeto de pesquisa do projeto coletivo que se volta ao saber profissional do professor que ensina matemática.
Analysis of Defects at Laser Welding of Heat-Resistant Alloy KhN45VMTYuBR
Authors: Baranov Dmitry A. , Parkin Anatoly A. , Zhatkin Sergey S.
Published: August 2021

The article presents the results of the impact of laser welding parameters on defect occurrence in the welded seam of the Ni-based heat-resistant alloy Kh45VMTYuBR applied for the manufacture of gas-turbine engines. On the basis of the research the authors conduct the analysis of dimensions as well as the number of pores and micro-cracks in the welded seam. The paper provides the recommendations on the selection of the laser welding mode for the heat-resistant alloy to reduce defect occurrence in a welding seam.
Development of a Mathematical Model for a Workpiece Heating and Cooling in a Protective Medium while Treatment under Pressure
Authors: Devyatiarova Victoria V. , Balakhnina Eugenia E. , Valeeva Lilya M.
Published: August 2021

The paper reviews and develops the mathematical model of plastic flow during the hot-forming processes. A flat non-stationary temperature problem for a cross-section of a long solid (rolled product) of arbitrary shape with different heat transfer conditions along the perimeter of the cross-section was considered. Equations for calculation of the thermal conductivity coefficient and heat capacity of tungsten billets were obtained in the temperature range of 700 - 1500°C, based on the literature data. Analytical dependences in form of regression equations were obtained, allowing for computer calculations of physical specifications of 11x11 mm VA grade tungsten billets in form of temperature functions with accuracy sufficient for practical calculations.
Microstructure Evolution and Mechanical Properties of Titanium Nickelide during Pressing in Equal-Channel Angular Matrix with Quasi-Small Angle of Channels Intersection
Authors: Naizabekov Abdrakhman B. , Kuis Dmitry V. , Kasperovich Andrey V.
Published: August 2021

The article presents the results of the analysis of the microstructure and mechanical properties of titanium nickelide formed during pressing in an equal-channel angular matrix with a quasi-small angle of channels intersection. The conducted studies have shown that pressing in an equal-channel angular matrix with a quasi-small angle of channels intersection ensures the formation of a homogeneous sub-ultrafine-grained structure in the titanium nickelide alloy, while the average grain size, decreasing by 100-200 times, is 0.3-0.5 microns, and the tensile strength increases to 1350 MPa in 6 passes, which is almost 90% higher than in the coarse-grained quenched state.
Effects of Heat Treatment on Microstructure Parameters, Mechanical Properties and Cold Resistance of Sparingly Alloyed High-Strength Steel
Authors: Poleckov Pavel P. , Nikitenko (Kupriyanova) Olga A. , Kuznetsova Alla S.
Published: August 2021

This study considers the influence of various heat treatment conditions on the change of steel microstructure parameters, mechanical properties and cold resistance at a temperature of-60 °C. The common behavior of these properties is considered depending on the heating temperature used for quenching and subsequent tempering. Based on the obtained results, heat treatment conditions are proposed that provide a combination of a guaranteed yield point σ0.2 ≥600 N/mm2 with a low-temperature impact toughness KCV-60 ≥50 J/cm2 and plasticity δ5 ≥17%. The obtained research results are intended for industrial use at the mill "5000" site of MMK PJSC.
Phase Transformations and Microstructure of the Alloyed Steels for Mining Application
Authors: Maisuradze Mikhail V. , Ryzhkov Maxim A. , Zhilyakov Arkadiy Yu.
Published: August 2021

The dilatometer study of the austenite transformations in steels with different chemical composition was conducted. The studied steels were classified as the air hardened steels of different alloying systems (Cr-Ni-Mo, Cr-Mn-Si-Mo and Cr-Mo-V) designed for the mining applications (rock drilling equipment, drilling instrument). The microstructure of the steels was investigated after continuous cooling at the rates of 0.1...30 °C/s from the austenitization temperature down to the ambient temperature. The CCT diagrams of the studied steels were plotted showing that the alloying with different set of elements can provide the desired hardenability and microstructure.
Solid-Phase Reduction and Separation of Iron and Phosphorus from Manganese Oxides in Ferromanganese Ore
Authors: Kosdauletov Nurlybay K. , Roshchin Vasiliy R.
Published: August 2021

The possibility of joint solid-phase reduction of iron and phosphorus from ferromanganese ore has been experimentally confirmed. Solid-phase reduction was performed at a temperature of 1000°C and exposure time of 2-5 hours, in a CO atmosphere, also produced the separation of the reduction products by melting. The distribution of iron and phosphorus was studied using an electron scanning microscope. The phase analysis of the samples was studied using a Rigaku Ultima IV X-ray diffractometer. The results were processed using the "Match" software. Reducing roasting in a CO atmosphere provides a transition from the oxide phase to the metallic phase of only iron and phosphorus without loss of manganese, thus increasing the concentration of MnO oxide in the residual oxide phase of the ore.
Theoretical and Experimental Studies of Sulfur and Boron Distribution between the Slag of the CaO-SiO2-B2O3-MgO-Al2O3 System and the Metal
Authors: Babenko Anatolij A. , Smirnov Leonid A. , Upolovnikova Alena G.
Published: August 2021

The equilibrium interfacial distribution of sulfur and boron was estimated using the HSC 6.1 Chemistry software package (Outokumpu) and the simplex-lattice planning method. Adequate mathematical models have been constructed in the form of III degree polynomial, which describe the effect of the composition of the studied oxide system on the equilibrium distribution of sulfur and boron between the slag and the metal. Generalization of the results of experimental studies and thermodynamic modeling made it possible to obtain new data on the influence of the basicity and content of B2O3 in the slag of the CaO-SiO2-B2O3-MgO-Al2O3 system on the interphase distribution of sulfur and boron. It was found that in the range of boron oxide concentration of 1.0-10%, an increase in slag basicity from 2 to 5 at 1600°C leads to an increase in the sulfur distribution coefficient from 1 to 20 and, as a consequence, a decrease in the sulfur content in the metal from 0.02 to 0.0014 %, i.e. an increase in slag basicity favorably affects the development of the metal desulfurization process. An increase in the B2O3 content from 2.0 to 10.0% in slags formed in the region of moderate basicity, not exceeding 2-3, is accompanied at 1600°C by a decrease in the boron interphase distribution coefficient from 450 to 150 and an increase in the boron concentration in the metal from 0.006 to 0.021 %, which indicates the progress of boron reduction from slag to metal. The shift of the formed slags to the area of ​​increased basicity up to 5.0 shows a high degree of boron reduction from slag to metal. The results of the laboratory experiment confirmed the results of thermodynamic modeling.
Influence of Rotary Friction Welding Parameters on Tensile Strength and Length of TMAZ of Dissimilar Welded Joints from 32G2 and 40KhN Steels
Authors: Atamashkin Artem S. , Priymak Elena Y. , Kuzmina Elena
Published: August 2021

In this work, pipe billets with a diameter of 73 mm and a wall thickness of 9 mm from steels 32G2 and 40KhN are friction welded with an aim to optimize the process parameters. The friction pressure, the forging pressure and the length of the fusion varied. After the implementation of various welding modes, tensile tests and metallographic studies were carried out. The optimal welding parameters have been established, which make it possible to obtain tensile strength at the level of the 32G2 base metal. The study results of the microstructure and SEM fractographs after the optimal welding mode are presented.
Aging of the OT4-VT23, VT6-VT23, VT19-VT23 Titanium Welded Pairs
Authors: Illarionov Anatoliy G. , Koemets Olga A. , Grib Stella V.
Published: August 2021

The structure, the phase composition and microhardness over the section of welded joints aged at 500 and 550 °C have been studied by means of structural and microdurometric analyzes. The welded joints of OT4-VT23, VT6-VT23 and VT19-VT23 titanium alloys pairs were obtained by the argon-arc welding with a nonconsumable tungsten electrode. It has been established that the aging at 500 °C for 8 hours promotes the decomposition of metastable phases (b, a”) which formed after welding in the welded joint of VT19-VT23 titanium alloys pair. The decomposition process leads to strengthening of the main zones of the welded joint (except for the parent metal of VT23 alloy) and provides a favorable smooth change of microhardness in the joint during the transition from one alloy to another. The aging at 500 and 550 °C during 8 hours of the welded joints of OT4-VT23, VT6-VT23 titanium alloys pairs also led to the development of the decomposition of metastable phases (b, a”, a’) in the weld and heat affected zones of the alloys being joined, but did not provide the required monotonic change in microhardness over the cross section of the joint.
Research of the Process of Production of Steel Square Continuous Billets for Rolling Balls of Large Diameter
Authors: Bykov Petr O. , Tussupbekova Maral Zh. , Absolyamova Dinara R.
Published: August 2021

The paper investigates the technology of production of steel billets continuously cast billets for rolling balls of large diameter. In Kazakhstan, in connection with the development of new copper deposits such as Aktogay and Bozshakol, the need for large diameter steel grinding balls for primary ore processing has increased. The main problem in the operation of large diameter grinding balls is the tendency of the grinding media to break during operation. The authors of the work investigated the process of production of steel billets continuously cast billets with a cross section of 150 × 150 mm for rolling balls of large diameter (d 125 mm) in the PB LLP "KSP Steel", which showed that the breaking of grinding balls is initiated mainly by the presence of internal discontinuities (gas axial looseness) in continuously cast billets. Studies have shown that the technological scheme for the production of grinding balls with a diameter of 125 mm from continuously cast billets with a section of 150 × 150 mm, including steel smelting in an arc furnace with steel finishing on a ladle-furnace unit, deoxidation with aluminum and degassing in a ladle vacuum apparatus, casting steel in a closed jet on a continuous casting and further production of rolled stock on a rough rolling mill ensures the absence of internal discontinuities (gas bubbles, axial looseness) in the workpieces and ensures the production of high quality balls.
Analytical Evaluation of Strengthening, Local Internal Stresses and Microderformations in Welded Joint Metal during Wet Underwater Welding
Authors: Maksimov Sergey Yu. , Berdnikova Olena M. , Prilipko Olena A.
Published: August 2021

Analysis of structural factor influence on local internal stresses and zones of deformation localization in upper and lower bainite structures in welded joints of low-alloy steel at wet underwater welding was performed. It is established that when welding joints under the water and applying an external electromagnetic field in the metal of the heat-affected zone (HAZ), a finer-grained substructure is formed with a general decrease in the dislocations density and with their uniform distribution. Estimates of the local internal stresses level considering the dislocation density distribution in the structural zones of their localization show that their maximum level is formed in the metal of the HAZ overheating region at welding without the external electromagnetic field along the upper bainite laths boundaries. The upper bainite structure is characterized by forming localized deformation zones, where the most significant dislocation density gradients are observed. This can lower the crack resistance of welded joints. Low values of local internal stresses are characteristic of welded joints obtained in the modes applying an external electromagnetic field. This is facilitated by the overall decrease in the dislocation density and their uniform distribution in the lower bainite structural components, which provides high crack resistance of welded joints.
Features of High-Temperature Synthesis in Clad Mechanocomposites of Ti-Al System
Authors: Sobachkin Alexey , Loginova Marina V. , Filimonov Valery Yu.
Published: August 2021

The influence of mechanoactivated reagents cladding on the structural-phase state of the SHS-products was investigated. Titanium and aluminum powders were used as reagents. Mechanical activation was performed on the AGO-2 planetary ball mill. The coating on Ti+Al mechanocomposite was carried out using magnetron installation “VSE-PVD-Power”. At deposition time of 40 minutes, the reaction start temperature increases from 525 °C to 648 °C (compared to reagents without cladding). It can be assumed that an increase in the thickness of the deposited SiO2 film serves as a barrier to the reaction start, thereby increasing ignition temperature. Apart from pretreatment, the phase composition of the final product contains intermetallic compounds TiAl, TiAl3, Ti3Al5, as well as the small amount of residual Ti. The main phase is TiAl.
Surfacing of Ti-Al System Mechanocomposites by Magnetron Deposition
Authors: Sitnikov Alexander A. , Yakovlev Vladimir I. , Popova Anastasia A.
Published: August 2021

The investigations of (Ti + Al)-SiO2 surfacing by magnetron deposition are presented in this article. The correlation between film`s thickness deposited on the particles by mechanocomposites and magnetron sputtering time was established. It was determined that the rational time for surfacing by Ti-Al mechanocomposites system is about 40 minutes. According that deposition time the thickness of deposited SiO2 films were obtained as 5.2 microns.
Determining Residual Stresses in Weld Joints of DN 850 Pipes by Spot Drilling Combined with Electronic Speckle Pattern Interferometry
Authors: Odintsev Igor N. , Plugatar Taras P. , Apalkov Andrey A.
Published: August 2021

Residual welding stresses affect significantly the strength, durability, and performance of structures. Therefore, there is an urgent need for developing and implementing techniques and equipment that allow reliably estimating stresses in experiments. This paper considers some aspects of the joint implementation of electronic speckle pattern interferometry and the spot drilling technique to determine these characteristics under the field conditions. The results of determining the distribution of residual stresses in the weld joint areas of DN 850 pipes are given for various welding modes. The study results are of independent significance and herewith, demonstrate the efficiency of the equipment developed to solve similar problems.
Modeling a Free Burnishing of a Powder Hollow Cylinder
Authors: Ryabicheva Lyudmila , Dyadichev Valery V. , Reshetnyak Denis V.
Published: August 2021

The paper presents the results of the computer modelling of the stressed state and relative density when burnishing a porous hollow cylinder, made from copper sintered powder material. The mathematical model, based on the theory of porous bodies’ plasticity, is used for the analysis. The paper researches the impact of the initial porosity of the material on the effective stresses distribution, relative density and force change when free burnishing of hollow cylinders. It is ascertained that with the decrease of the initial porosity of the sintered material there is the increase of the burnishing force, stresses rate and relative density on the inner sur-face of a hollow cylinder. For porous materials at a certain stage of burnishing, the deformation zone is transformed into the compaction zone with a high relative density which de-creases while moving away from the inner surface of hollow cylinders. The maximum value of the relative density is implemented directly on the inner surface of hollow cylinders; along with this the density value is evenly distributed on the inner wall.
The Influence of Friction Deformation on the Microstructure and Hardening of Beryllium Bronze
Authors: Baraz Vladislav R. , Estemirova Svetlana Kh. , Ishina Elena A.
Published: August 2021

The peculiarities of the microstructure and properties of BrBNT1.7 beryllium bronze tape samples were studied: the samples were subjected to dispersion hardening as a result of quenching in a supersaturated solid solution and aging. Friction deformation in a dry friction mode provides additional effective hardening while maintaining increased plasticity (bending-and-unbending test).
Aspects of Superplasticity of Metals
Authors: Kalpin Yili G. , Tipalin Sergey A. , Ryabov Vladimir A.
Published: August 2021

The assumption that stable deformation depends on the strain rate is verified. In case of stable deformation, local deformation in a weak cross-section leads to hardening of the metal. Its effect exceeds the effect of reducing the cross-sectional area, as a result of which the deformation affects other sections as well, while the deforming force increases. At low strain rates that are characteristic of superplasticity, the strain inside the grains cannot be really great. During hot deformation, there is resistance to intragrain deformation, intergrain sliding, and accommodation of grain boundaries. The phenomenon of superplasticity is investigated and fixed under stable and unstable deformation, which leads to contradictory results. It is shown numerically that the function of deformation resistance and stable deformation rate increases only when the deformation is carried out with acceleration. The effect of hardening of the surface layer of metal grains on the deformation parameters is described.
Structure and Phase Composition of the Al-Ti System Composites after Heat Treatment
Authors: Shmorgun Victor Georgievich , Bogdanov Artem I. , Kulevich Vitaliy P.
Published: August 2021

The studies results of the titanium with aluminum diffusion interaction at a temperature of 650 oC are presented. The phase and chemical composition of the diffusion interaction zone, the nature of the change in its thickness from the exposure time are determined. It is shown that accelerated cooling of explosion-welded composites from the heat treatment temperature leads to spontaneous separation of the aluminum layer with the formation of a coating based on the TiAl3 intermetallic compound on the titanium surface.
Analysis of Remagnetization Processes of High-Anisotropic Alloy after Heat Treatment
Authors: Lileev Alexey S.
Published: August 2021

The simulation of the Sm(Co, Fe, Cu, Zr)7.5 type alloy domain structure formation after various thermal treatments was carried out by FMRM program based on a phenomenological approach to the analysis of the uniaxial highly anisotropic ferromagnets demagnetization processes. It is shown that the domain structure of the alloy in the thermally demagnetized state expands as the coercive force of the alloy decreases. It is noted that the domains size increasing process is associated not only with a decrease in the coercive force but also with a change in the influence of the magnetostatic interaction.
The Surface Hardening of Parts of Liquid Dampers Made of High-Strength Steels
Authors: Muratov Vladimir S. , Yakimov Nikolay S.
Published: August 2021

Variants of air-plasma sputtering (APS) and supersonic gas-flame sputtering in the HVOF modification of wear-resistant coatings on 30HGSN2A steel, used for the manufacture of rods of liquid dampers, have been worked out. Powder mixture designated as mixture A with chemical composition (wt%): 85 % chromium carbide (Cr3C2) powder and 15 % steel powder consisting of 20 % chromium and 80 % nickel were used for spraying. During the quality control of the applied coatings were evaluated: appearance, thickness, adhesion strength, microhardness and porosity. The phase composition of the coatings was also determined.
The deposition modes are determined for varying the size and shape of powder mixture particles, as well as the deposition distances, which allow obtaining coatings with the required values of microhardness, adhesion strength and porosity. Such coatings can be obtained by using each of the three powder mixtures studied. The highest microhardness of the coating (11500-12100 MPa) was achieved using the powder mixture C (86%WC + 10%Co + 4%Cr) – and the HVOF method. The phase composition of this coating is represented by WC (base) and W2C carbides. The maximum shear strength (114 MPa) was achieved using a powder mixture A (85% Cr3 C2 + 15%X20H80) and the APS method. In the first variant, the porosity of the coating is 1.8-2.0 %, in the second - 5-8 %.
Influence of Fillers on the Viscosity Properties of One-Pack Polyurethane Sealants
Authors: Timakova Kseniya A. , Panov Yuriy T. , Timakov Evgeniy A.
Published: August 2021

The paper investigates the effect of fillers on the viscosity properties of one-pack polyurethane sealants. It is noted that with the introduction of such mineral fillers as Mikarb, Midol, MTD2 chalk and aluminum hydroxide, the dynamic viscosity of the composition increases uniformly, while when filled with chemically precipitated Calofort SV chalk and MT-GShM talc, an abnormally sharp increase in viscosity is observed. Such an increase in viscosity for Calofort SV is explained by a highly developed surface, in contrast to other fillers. Talc is characterized by a plate-like shape of particles, which leads to a complex orientation of talc particles in the composition and shear difficulties.It was found that a sealant filled with chemically precipitated chalk has more than 100 pts. wt.(parts by weight), per 100 pts. wt. of the prepolymer under the influence of shear forces (at a constant shear rate) during the first 10 minutes of exposure, a sharp decrease in viscosity is observed, which is characteristic of thixotropic compositions, reaching a constant value after 5-10 minutes. After 10 minutes, the thixotropy of the sealant is restored. Talc does not impart thixotropic properties to the sealant composition.
A Study on Chemical Ageing of Composite Ribbed GFRP Bars under Load
Authors: Sakoshev Zakhar G. , Blaznov Aleksey N. , Firsov Vyacheslav V.
Published: August 2021

Here we explored the chemical durability of glass fiber-reinforced polymer (GFRP) bars under load. Three batches of ribbed GFRP bar specimens were fabricated using binder matrices: ED-22+isomethyltetrahydrophthalic anhydride (iso-MTGFA), ED-22+Ethal-450 and NPPN-631+ iso-MTGFA. As the reinforcing filler, we used an EC17 glass roving (for all the specimen batches). The specimens of each batch were aged in a 1 N alkaline NaOH solution at 60 °C for 2000 hrs. The ageing was performed under a 300 MPa load (30% of the failure stress). The tensile strength of the specimens from each batch following ageing was measured. The tensile test results demonstrated that that the strength loss of the specimens following chemical ageing was 58.9% for batch 1 based on ED-22+iso-MTGFA, 6.6% for batch 2 based on ED-22+Ethal-450, and 33.6% for batch 3 based on NPPN-631 + iso-MTGFA. The specimens of batch 2 based on ED-22+Ethal-450 exhibited the greatest resistance to the NaOH alkaline solution (a strength loss of 6.6%).
Investigation of Deformation Work in Layers of Explosion-Welded Composite Al-Cr-St3
Authors: Kuz'min Vladimir I. , Lysak Vladimir I. , Kuz’min Evgeniy V.
Published: August 2021

The article is aimed at studying the distribution of deformation work in the layers of the explosion-welded composite Al-Cr-St3 with a diffusion barrier. It is established that the thickness of the chromium layer does not affect the value of the total deformation work. An increase in the thickness of the chromium interlayer leads to a decrease in the proportion of deformation work and strength.
Experimental Study of Tensile Preloading Influence on the Mechanical Behaviour of Pseudo-Ductile Hybrid Composite under High-Velocity Impact
Authors: Olivenko Nikita A. , Kudryavtsev Oleg A. , Zhikharev Mikhail V.
Published: August 2021

The hybridisation of fibre-reinforced plastics is one of the perspective technological methods that make it possible to reduce the sensitivity of polymer composites to stress concentration and increase their damage tolerance. In this case, hybridisation means a combination of different types of reinforcing fibres in one yarn, one layer or one package. In most published papers, the authors investigated the mechanical behaviour of hybrid fibre-reinforced plastic under static loading or low-velocity impact conditions only. At the same time, statically preloaded structures made of composite materials can also be subjected to high-velocity impact. Tensile or compressive preloading affects not only the amount of energy absorbed by the composite but also changes the deformation and fracture pattern. This paper presents the results of the experimental study of the mechanical behaviour of a woven carbon/aramid hybrid composite under tensile preloading and high-velocity impact. Pre-tensioned specimens of homogeneous and hybrid composites were subjected to a high-velocity impact by a steel spherical projectile with the velocities up to 900 m/s. The experimental results showed that the hybrid composite had the lowest sensitivity of the ballistic limit to the tensile preloading.
Experimental and Computational Study of Ultra-Low-Cycle Fatigue of Fabric-Reinforced GFRP
Authors: Leshkov Egor V. , Sapozhnikov Sergey B. , Kudryavtsev Oleg A.
Published: August 2021

The development of weight-efficient reusable launch systems has increased the urgency of problems associated with ultra-low-cycle fatigue. In this paper, one-sided three-point bending cyclic tests of GFRP specimens were performed. Parallel to the cyclic tests, registration of acoustic emission signals has been performed to identify the main damage mechanisms underlying ultra-low-cycle fatigue of fabric-reinforced composites. The obtained displacement-time diagrams showed a noticeable effect of creep on the deformation process. It was found that fiber fracture is the main mechanism of microdamage accumulation. A phenomenological three-element model based on the Norton-Bailey law and the Masing structural model was proposed. The model allowed describing both the deformation process of the specimens in time and their durability at different load levels. An optimization algorithm based on the deformable polyhedron method was used to find the optimal set of the model parameters.
Comparative Analysis of the Physical and Mechanical Properties of Composites with Functional Fillers Based on Waste
Authors: Barakhtenko Vyacheslav V. , Sahabutdinova Tatiana H. , Novikov Yury V.
Published: August 2021

The article is devoted to research in the development of composite materials based on polyvinyl chloride and industrial waste from the metallurgical, energy and mining industries. The properties of dispersed waste have been studied, which make it possible to speak of the possibility of their use as fillers for polymer compositions. A comparative analysis of the tested physical and mechanical properties is carried out, depending on the characteristics of the particle size of the fillers. It was revealed that from the point of view of construction materials, all the wastes under study can be used as fillers. The development will make it possible to dispose of industrial waste to obtain useful products and save natural non-metallic materials used in the creation of composites.
Thermodynamic Assessment of Phase Equilibria in the SrO-Al2O3 System
Authors: Makrovets Larisa A. , Samoilova Olga V. , Bakin Igor V.
Published: August 2021

Thermodynamic modeling of phase equilibria with the subsequent construction of the phase diagram of the SrO–Al2O3 system has been carried out. To calculate the activities of the oxide melt in the course of this work, we used the approximation of the theory of subregular ionic solutions, with the most optimal values of the energy parameters Q1112 = –104 349: Q1122 = –217 689; Q1222 = –104 436 J/mole. The results obtained for the liquidus line in this work are in good agreement with the literature experimental data. In the course of the calculation, the values of the equilibrium constants for the formation of strontium aluminates from the components of the oxide melt were estimated.