bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigar e explorar com tecnologia
Authors: Batista Carolina Cordeiro , Paulo Rosa Monteiro 
Published: June 2021

Neste texto descrevemos a experiência vivida ao estar junto a um grupo de professores analisando práticas de ensino de matemática desenvolvidas por meio de tarefas de investigação com uma tecnologia - o software GeoGebra, cujo objetivo é expor situações que compreendemos ser relevantes para o professor quando ele se volta para a sua prática de investigação com tecnologia. Esse grupo foi constituído para a produção dos dados de uma pesquisa de Doutorado em andamento. O grupo reuniu-se quinzenalmente com a pesquisadora desde o 2º semestre de 2018 até o final de 2019. A experiência aqui descrita é um recorte das ações desenvolvidas nesse período. Iniciamos o texto apresentando nossas compreensões acerca do trabalho de investigação com tecnologia. Seguimos com a descrição do contexto em que tarefas foram planejadas e apresentamos uma delas, proposta por um dos professores do grupo, desenvolvida com seus alunos e discutida com os demais participantes, colegas de uma mesma escola. A aula foi gravada e, posteriormente, editamos o vídeo fazendo recortes que pudessem expor as ações dos alunos e a interação com o professor. Esse vídeo editado com os recortes da aula foi assistido pelo grupo para que eles pudessem discutir o que se mostrava relevante nas ações dos alunos. Trazemos, então, uma descrição dessa discussão dos professores na qual foram destacados os modos de eles lidarem com o erro do aluno, os questionamentos feitos e seus objetivos, os conteúdos que perceberam que os alunos compreenderam ao realizar as explorações com o software, as possibilidades que viram para avançar com os conteúdos e o destaque feito para a importância de estarem no grupo discutindo e buscando compreender aspectos da própria prática.
Palavras-chave: Educação Matemática; Estudo de Aula; Fenomenologia; Formação de Professores; GeoGebra.
Álgebra islâmica de al-Khwarizmi a Omar Khayyam
Authors: Silva Rosangela Araújo da , Morey Bernadete Barbosa 
Published: June 2021

A álgebra das equações tem seus primórdios na ciência islâmica medieval. Este trabalho é um recorte de uma pesquisa doutoral mais ampla em desenvolvimento que envolve a análise do tratado algébrico de Omar Khayyam (1048-1131), cujo título é Al-Risala fi-l-barahin ‘ala masa’il al-jabr wa-l-muqabala (Tratado sobre demonstrações dos problemas da álgebra e almuqabala). Ao se tratar de álgebra das equações, torna-se imprescindível citar o sábio al-Khwarizmi (780-850), que escreveu um tratado algébrico, conhecido até os dias de hoje como a Álgebra de al-Khwarizmi (780-850). O presente trabalho é sobre o desenvolvimento da álgebra islâmica de al-Khwarizmi a Omar Khayyam. O estudo tem como objetivo descrever o que foi elaborado e desenvolvido em álgebra islâmica de al- Khwarizmi a Omar Khayyam. Possibilitando um melhor entendimento do significado da álgebra de Khayyam, pois em seu tratado ele menciona alguns sábios que estudaram álgebra antes dele. A pesquisa foi realizada por meio de pesquisa bibliográfica, a princípio na plataforma de periódicos da Capes e para complementar utilizamos a busca pelas biografias dos sábios para descrever a trajetória, na página eletrônica Mac Tutor. Apresentamos este percurso de desenvolvimento da álgebra, como resultado obtido, considerando que novos estudos podem ampliá-lo. Os estudiosos que encontramos foram: Al-Khwarizmi resolvendo equações lineares e quadráticas, apresentando a álgebra como uma prática para resolver problemas e nomeando a álgebra; al-Mahani que chegou em uma equação envolvendo cubos, quadrados e números; Abu Kamil que aplicou a álgebra no pentágono e no decágono regular; al-Karaji que aritmetizou a álgebra, primórdios para o modelo da álgebra moderna; e chegando a Omar Khayyam que desenvolveu por meio de intersecções de seções cônicas um método geométrico de resolver equações cúbicas.
Palavras-chave: Álgebra; Al-Khwarizmi; Desenvolvimento; Equações; Omar Khayyam.
Trissecção do ângulo obtuso com origami
Authors: Graciolli Carolina Yumi Lemos Ferreira , Batista Carolina Cordeiro , Shintani Rodolfo Masaichi 
Published: June 2021

Neste texto apresentamos o problema da trissecção do ângulo, conforme tratado no método elaborado pelo matemático francês, Jacques Justin, com o objetivo de expor uma proposta para investigação desse problema em sala de aula por meio de origami. Para isso, iniciamos a discussão trazendo um breve relato histórico acerca da constituição da matemática como um campo científico, bem como do contexto que levou ao surgimento dos problemas clássicos da geometria. Destacamos, dentre eles, o problema da trissecção do ângulo e seguimos explicitando aspectos relativos às possíveis motivações para o seu surgimento e à impossibilidade de sua resolução por meio da régua e do compasso não graduados. Como alternativa para mostrá-lo, sem recorrer aos instrumentos utilizados pela geometria euclidiana, apresentamos uma possibilidade que se utiliza do origami. Ademais, discutimos modos de desenvolver habilidades e competências citadas na Base Nacional Comum Curricular (BNCC) e de favorecer a aprendizagem de conteúdos previstos no currículo escolar – como aqueles relativos à semelhança e à congruência de triângulos – por meio de um trabalho de investigação matemática, no qual, a partir das dobras realizadas no papel para verificar o problema da trissecção, sugerimos que os alunos sejam desafiados a levantar e a testar hipóteses para buscar soluções para o problema a partir das regularidades identificadas. Nessa postura de levantar hipóteses, testar e mostrar, compreendemos que há a possibilidade de o trabalho de sala de aula, ainda que seja dado com um nível menor de dificuldade, tornar-se mais próximo do trabalho desenvolvido por matemáticos profissionais. Como considerações finais, destacamos que a investigação matemática atrelada ao trabalho com origami abre possibilidades para o desenvolvimento de tarefas que dão um novo significado à matemática escolar.
Palavras-chave: Dobradura; Ensino Médio, Problema da Trissecção; Educação Matemática.
Identifikasi Sedentary Behaviour di Masa Pandemic Covid-19: Narrative Review
Authors: Wardhani Riska Risty , Muflihah Nurul 
Published: June 2021

Pembatasan sosial, isolasi dan karantina merupakan salah satu cara untuk mencegah penyebaran COVID-19 yang lebih luas. Meskipun jarak sosial dapat memperlambat penyebaran COVID-19, tetapi orang akan menghabiskan sebagian besar waktunya di rumah dan tidak aktif secara fisik atau membentuk perilaku menetap atau sedentary behaviour. Tujuan penelitian ini untuk mengidentifikasi adanya perilaku menetap atau sedentary behaviour di masa pandemic COVID-19. Metode Â penelitian ini menggunakan metode Narrative Review. Pencarian jurnal melalui portal jurnal online seperti Google Scholar, PubMed, dan MedLine sesuai dengan kriteria inklusi. Hasil penelitian ini berdasarkan review terhadap 11 jurnal dari berbagai negara yang berbeda,semua mengidentifikasi terjadinya sedentary behaviour di masa pandemic COVID-19. Kesimpulan penelitian membuktikan adanya identifikasi sedentary behviour di masa pandemic COVID-19.
Merdivenli Sokaklarda Sosyal Mekân Oluşumuna Etki Eden Unsurlar ve İstanbul’dan Üç Örnek İçin Değerlendirme
Authors: CİRİTCİ İlke , YÜCEL Gül 
Published: June 2021

Çalışmada merdivenli sokaklarda sosyal mekân oluşum potansiyeli ve buna etki eden unsurlar tartışılmıştır. Çalışma kapsamında sokak, merdivenli sokak, sosyal mekân, kamusal alan, aidiyet kavramları mimarlık literatüründe araştırılmış, kentle ilişkilendirilerek, kavramsal bağlar kurulması amaçlanmıştır. Dünyanın birçok kentinde ziyaret edilen popüler merdivenli sokaklar olduğu gibi, İstanbul’un tarihi bölgelerinde de ilgi çeken merdivenli sokaklar bulunmaktadır. Nitel araştırma yöntemi ile merdivenli sokakların kamusal alan kullanımı ulaşılabilirlik, konfor, etkinlik ve estetik parametreleri üzerinden incelenmiş, bu kapsamda sosyal mekân olarak kullanım başarısı, merdivenlerin potansiyelleri, yerinde gözlem ve ölçüm yöntemleri ile tespit edilmiştir. Çalışma kapsamında İstanbul tarihi yerleşim alanlarında bulunan merdivenli sokaklardan Balat Merdivenli Mektep Sokak, Beyoğlu Hacı Ali Sokak ve Üsküdar Yeni Dünya Sokak fiziksel ve sosyal mekân özellikleri açısından ayrıntılı incelenmiş, tespitler çerçevesinde merdivenli sokakların bulundukları çevreye ve yaşam tarzına katkıları değerlendirilmiştir.
Merdivenli sokakların sosyal mekân olarak var olmaları ve kent yaşamına katılmaları sosyal medyadaki görünürlüğü üzerinden, fotoğraf ve video paylaşım uygulaması “Instagram” üzerinden araştırılmış, merdivenli sokakların sosyal medyada görünürlüğü kullanıcıların paylaşımları üzerinden değerlendirilmiştir. Araştırma sonuçları merdivenli sokakların çevresindeki yapıların ve fiziksel özelliklerinin sosyal mekân oluşum potansiyeline büyük oranda katkı sağladığını göstermektedir.
High-Temperature Performance of Self-Healing SiC-YSZ Thermal Barrier Coatings Deposited by Using Various Plasma Spray Concepts
Authors: Hassanzadeh Mohammad , Sokołowski Paweł , Musalek Radek , Medricky Jan , Csaki Stefan 
Published: June 2021

Abstract
In this study, a novel self-healing concept is considered in order to increase the lifetime of thermal barrier coatings (TBCs) in modern gas turbines. For that purpose, SiC healing particles were introduced to conventional 8YSZ topcoats by using various plasma spray concepts, i.e., composite or multilayered coatings. All topcoats were sprayed by SG-100 plasma torch on previously deposited NiCrAlY bondcoats produced by conventional atmospheric plasma spraying. Coatings were subjected to thermal conductivity measurements by laser flash method up to 1000°C, isothermal oxidation testing up to 200h at 1100°C and finally thermal cyclic fatigue (TCF) lifetime testing at 1100°C. Microstructural coating evaluation was performed by scanning electronic microscope (SEM), in the as-produced and post high-temperature tested states. This was done to analyze the self-healing phenomena and its influence on the high-temperature performance of the newly developed TBCs.
Contribution in Optimization of Honeycomb Abradable Seals Structure
Authors: Pathak P. , Dzhurinskiy D. , Elkin A. , Shornikov P. , Dautov S. , Ivanov V. 
Published: June 2021

Abstract
The abradable coatings had significantly enhanced turbomachinery performance by acting as a sacrificial seal between rotating blades and stationary casing. Further improvement in seal design to meet the higher energy demand and increase the service time has been the key challenges to solve in the gas turbine industry. Honeycomb seals have become the industry standard clearance seal technique due to their unique design and high structural strength with minimum weight. The present study proposes a concept to form a thermal shock resistance structure to achieve higher temperature capability and improve the reliability of abradable seal structures. A cavity layer of honeycomb seal structure made of SS 321 alloy was coated with advanced high-temperature ZrO2+7.5%Y2O3+4% polyester seal material using TriplexPro-210 plasma spray system. The integrity of a seal structure was assessed by a cross-sectional analysis and evaluation of the coating microstructure. Additionally, the microhardness test was performed to estimate coating fracture toughness, and Object-Oriented Finite Element analysis was used to assess its thermo-mechanical performance. The concept proposed in this study should be further validated to develop the most capable innovative technology for advanced gas turbine abradable seal structures.
Principle and Practice to Achieve Improvements in TBC Thermal Cycle Lifetime
Authors: He Jianhong , Sharobem Timothy , Zhou Naixie , Dwivedi Gopal 
Published: June 2021

Abstract
As a critical technology, thermal barrier coatings (TBC) have been used in both aero engines and industrial gas turbines for a few decades, however, the most commonly used MCrAlY bond coats which control air plasma sprayed (APS) TBC lifetime are still deposited by the powders developed in 1980s. This motivates a reconsideration of development of MCrAlY at a fundamental level to understand why the huge efforts in the past three decades has so little impact on industrial application of MCrAlY alloys. Detailed examination of crack trajectories of thermally cycled samples and statistic image analyses of fracture surface of APS TBCs confirmed that APS TBCs predominately fails in top coat. Cracks initiate and propagate along splat boundaries next to interface area. TBC lifetime can be increased by either increasing top coat fracture strength (strain tolerance) or reducing the tensile stress in top coat or both. By focusing on the reduction of tensile stress in top coats, three new bond coat alloys have been designed and developed, and the significant progress in TBC lifetime have been achieved by using new alloys. Extremely high thermal cycle lifetime is attributed to the unique properties of new alloys, such as remarkably lower coefficient of thermal expansion (CTE) and weight fraction of β phase, absence of mixed / spinel oxides, and TGO self repair ability, which cannot be achieved by the existed MCrAlY alloys.
Cold Spray Deposition of Heat-Treated Inconel 718 Powders
Authors: Perez Lorena , Colburn Jake , Brewer Luke N. , Renfro Michael , McKechnie Tim 
Published: June 2021

Abstract
In this work, Inconel 718 gas-atomized powder was successfully heat treated over the range of 700-900°C. As-atomized and as-heat treated powders were cold sprayed with both nitrogen and helium gasses. Cold spray of high strength materials is still challenging due to their resistance to particle deformation affecting the resulting deposit properties. Powder heat treatment to modify its deformation behavior has recently been developed for aluminum alloy powders, however, there is no literature reported for Inconel 718 powders. The microstructural evolution of the powder induced by the heat treatment was studied and correlated with their deformation behavior during the cold spray deposition. Deposits sprayed with heat-treated powders at 800 and 900 °C and nitrogen showed less particle deformation and higher porosity as compared to as-atomized deposit associated to the presence of delta phase in the powders precipitated by the heat treatment. In contrast, deposits sprayed with helium using both powder conditions, as-atomized and as heat-treated powders, showed high particle deformation and low porosity indicating that the type of gas has a greater effect on the particle deformation than the delta phase precipitated in the heat-treated powders. These results contribute to understanding the role of powder microstructure evolution induced by heat treatment on the cold spray deposits properties.
Effect of Heat Treatment on Residual Stress of Cold Sprayed Nickel-Base Superalloys
Authors: Shrestha Deepika , Azarmi Fardad , Tangpong X.W. 
Published: June 2021

Abstract
Residual stress can be developed in most thermally sprayed coatings due to the momentum of molten particles during impact, and heat transfer during solidification of the splats. Another reason for residual stress built-up in thermally sprayed coatings is due to splat curl-up during solidification and the differences in thermal expansion coefficients between the coating and the substrate. However, in the cold spraying process, it is believed that the main reason for residual stress formation is plastic deformation during impact and flattening of solid particles. Residual stresses can drastically influence coating quality and reduce its service time. In this study, residual stress is measured for two well-known nickel based super alloys (Inconel 625 and Inconel 718) deposited on 7074 aluminum alloy substrates by the cold spraying technique. Residual stress in Inconel 625 was found to be highly tensile on the surface and compressive on the subsurfaces. After heat treatment the residual stress was relieved and was compressive in nature. Whereas for Inconel 718, residual stress was compressive on the surface and tensile on the subsurfaces in the as-sprayed condition. After heat treatment, the residual stress was compressive with increased magnitude. The heat treatment at 800°C made the residual stress more compressive. The porosities of both Inconel 625 and Inconel 718 were reduced after heat treatment.
Strain Gradient Plasticity Modeling to Evaluate Material Plastic Deformation Behavior During Cold Gas Dynamic Spray Process
Authors: Dzhurinskiy D. , Dautov S. , Shornikov P. , Akhatov I. Sh. 
Published: June 2021

Abstract
Severe plastic deformation (SPD) is the main feature of the Cold Spray (CS) process, which might result in producing metal grain refinement under extensive hydrostatic pressure and high strain rate loading conditions. In this study, an anisotropic strain gradient plasticity model (SGP) is presented to predict materials behavior in CS process. The enhanced dislocation densities produced throughout particle deformation affect coating material properties and modify their thermodynamic characteristics and kinetics of resistance to plastic deformations. This study also demonstrates that the SGP model can describe the experimentally observed trends and account for homogenization of the accumulated strains under dynamic recrystallization conditions. The evolution of statistically stored dislocation density through the characteristic material length scale parameter is in good agreement with experimental results and data reported by other research groups. The proposed SGP modeling is suggested as an express method to evaluate the advanced coating and additively manufactured materials, and powder feedstock used in thermal spray and 3D manufacturing applications.
RESULTS OF X-RAY AND DENSITOMETRIC INVESTIGATION IN PATIENTS WITH DESTRUCTIVE FORMS OF APICAL PERIODONTITIS IN EARLY FOLLOW UP PERIOD
Authors: Lysokon Yu. Yu. , Iskiv M.O. , Luchinskyi M.A. 
Published: June 2021

This article presents a comparative analysis of the effectiveness of various treatment approaches, including bone mixture “mp3, Osteobiol, and platelet-enriched plasma, in the therapy of destructive forms of apical periodontitis in the early follow-up. The aim of this work is to investigate the dynamic changes in radiological and densitometric parameters depending on the treatment methods for patients with destructive forms of apical periodontitis in the early follow up period. The study involved 185 patients with destructive forms of apical periodontitis, who were examined and receive the treatment. The subjects were divided into 4 groups. Measurements of the size of the lesion in the bone tissue (for lesions of round shape) were performed by the formula: S = πr2. The area of lesions of elliptical shape was measured by the formula S = π ab, where π = 3.14; r = the radius of the circle; a = the value of the major half-axis of the ellipse; b = the length of the small half-axis of the ellipse. After 3 months of the follow up, the patients of group IV, who received the composition of platelet-rich plasma and osteoplastic material mp3 OsteoBiol, demonstrated an increase in the number of the lesions of the periapical zone sized 1.6-10 mm2 in 1.7 times, while the number of the subjects with foci of bone destruction sized 11–20 mm2 and 21–30 mm2 lowered in 2.8 times and 2.0 times, respectively. In 3 months of the follow up period, the patients of group IV showed the values of Rtg scoring of bone tissues destruction in the apical area with a lesion area of 1.6-20 mm that averaged 2.13±0.10 scores and indicated a reduction of the periapical process by 1/3.
The average Rtg score in the patients of group IV (0.92 ± 0.10 points) was significantly higher than in the individuals in groups I and II, p, p 1 <0.01, and was equal to the findings obtained in the individuals of the group III, p2 > 0.05. The relative indicator of bone tissue repair in this follow up was characterized by the minimum values in the individuals of groups I and II: 0.49 ± 0.05 and 0.57 ± 0.06, p <0.05, respectively. In the groups III and IV, the value of the relative indicators of bone tissue repair were significantly higher and scored 4.82 ± 0.54, p, p1 <0.01, and 6.94 ± 0.77, p, p1 <0.01, p2 < 0.05, respectively.
At the same time, the average Rtg scoring in patients of group IV was significantly higher than in the participants of groups I and II, and was identical to the values in the subjects of group III. This study has demonstrated the successful outcomes of the treatment of dystrophic forms of apical periodontitis in the early follow up period when applying the composition based on platelet-rich plasma and osteoplastic material "mp3 OsteoBiol".
STRESS-PROTECTIVE EFFECTS OF NEW MEDICINAL FORM WITH GLYCINE AND MAGNESIUM CITRATE
Authors: Devіatkina N. M. 
Published: June 2021

Introduction. Stress disorders are common in clinical practice, and their treatment requires selective medication choice. Among the drugs having anxiolytic and sedative effects, glycine and magnesium compounds are being intensively investigated and the options of producing sublingual tablets based on these substances seem to be promising. The aim of this study is to investigate the effects of glycine and magnesium citrate and their combination on glycine and magnesium citrate on somatic parameters (Selye's triad) under the stress conditions and to determine the most effective composition of the compounds.
Materials and methods. The experiments were carried out on 76 white rats. The substances were administered sublingually and then the animals were kept in the small cages for 6 hours in order to simulate immobilization stress. At the end of the stress exposure, the rats were euthanized and the relative masses of the thymus and adrenal glands as well as a presence of ulcers and haemorrhages in the stomach were determined. Statistical processing was performed using the Statistica for Windows 8.0 software.
Results and discussion. Immobilization stress resulted in a decrease in the relative weight of the thymus in the rats without significant changes in the weight of the adrenal glands and intense ulceration in the stomach. Prophylactic use of the compounds under the study and their combinations prevented the stress-induced involution of the thymus. The most pronounced protective effect was demonstrated by the combination of 100 mg glycine and 250 mg magnesium citrate and glycine itself. At the same time, the relative mass of the adrenal glands did not change significantly. The lowest incidence of ulcerative lesions was observed in the groups of animals who received the combinations of glycine (100 mg) and magnesium citrate (250-350 mg) or glycine (100 mg) separately. This scheme leads to a decrease in the number and area of gastric ulcers as compared to the control group. Magnesium citrate in doses of 250 mg and 350 mg was found not as effective in protecting the gastric mucosa.
Conclusion. Acute immobilization stress causes involution of the thymus and gastric ulceration, but does not result in adrenal hypertrophy. According to the findings obtained by the Selye triad study, a combination of 100 mg glycine and 250 mg magnesium citrate and glycine separately in a dose of 100 mg have showed the highest prophylactic effect.