bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment-for-Learning Teaching Mode Based on Interactive Teaching Approach in College English
Authors: Sun Rui , Zhang Huihui , Li Jing , Zhao Jing , Dong Peipei
Published: November 2020

English teaching plays an extremely important role in college education. It can not just improve students’ English level, but also help students adapt to the increasingly open and complex society. Besides, it is an important foundation for students to further go to the world and integrate in the world development trend. Although English teaching has received attention of various colleges and universities, there are still many problems in college English teaching, and the teaching effect is not obvious. To make teaching conform to the rapid development of the new education environment and make teaching practice more fitted with the standard of modern education, teaching mode reform for college English is imperative. Based on the teaching idea of “assessment for learning”, the teaching management system was designed in this study, including three steps: teaching intelligence system, assessment and test system, and information feedback system. Meanwhile, interactive teaching approach was combined to plan the interactive teaching process of college English course, including the process of proposing and solving questions, independent thinking and cooperative learning module, and leaning achievement exchange activity. In the end, assessment-for-learning teaching mode was used to collect the data of four dimensions (degree of learning engagement, completion degree of English learning content, degree of English learning interaction, and English learning effect) and the learning performance evaluation system supported by big data was established. The experimental results show that the teaching mode in this study could effectively improve students’ learning performance and enhance their actual English application ability.
Academic Support for ELL and Immigrant Adolescents
Authors: Zengaro Sally , Zengaro Franco , Ali Mohamed A.
Published: November 2020

Academic success is important for all children and adolescents. However, ELL and immigrant students often face greater challenges than other students. For this reason, academic support is critical to student success. This chapter addresses the academic success of ELL and immigrant students in high school. It begins with the assumption that academic success is multifaceted and not simply a matter of academic readiness. In particular, this chapter examines the importance of academic support and the positive interaction between family, teachers and students necessary for students' academic success.
#BlackGirlMagic
Authors: Mbinjama-Gamatham Adelina
Published: November 2020

This chapter explores the relevance of Immanuel Kant's categorical imperative to critique the unintended, subliminal evil representations in Shonda Rhimes's work. Kant's moral theory is used to re-think evil in the way that Rhimes portrays Annalise Keating (Viola Davis) in How to Get Away with Murder (2014-) as an influential defense attorney and law professor who goes to extreme lengths to get what she wants, even if her behavior is considered bad or evil. This chapter argues that Rhimes's work challenges the systemic racism and stereotypical portrayals of Black women in television, as she not only focuses on the bad or evil doings of her Black characters but also on what makes them powerful, good and emblematic of #BlackGirlMagic.
Question Concerning Evil in the Age of New Television
Authors: Deniz Kemal
Published: November 2020

The new developments and transformations that changed the television have also some outcomes about content, style, and performanses in the productions. Thus, quality drama series on dijital television and internet subscription TV platforms like Netflix are getting more attention of the audience. New or sub-genres, anti-heroes, muli-protagonists, moral dilemmas, new inquiries in socio-psychologycal level caused distinction between good and evil becomes more complex in this djital transformation age of television. In this context, Money Heist, which contains a harsh system criticism behind the robberies in its narrative, is considered a symbol of resistance with its unique iconography created by its aesthetics, genre, multi-protagonist characters and story, gained big attantion from global audiences. To understand how Money Heist achieved this audience support, it is evaluated in the context of genre, character structure, and iconography that created a symbolism of resistance in a global scale, considering the developments in television by the digital transformation.
The Growth Effects of Financial Development Over Economic Cycle in South Africa
Authors: Nuru Naser Yenus , Gereziher Hayelom Yrgaw
Published: November 2020

This study examines the effects of financial development, proxied by domestic credit, on growth for South Africa across the states of the economy over the sample period 1970Q1-2019Q3. To address this point, the authors use Jorda's local projection method to generate impulse response functions for this small developing open economy. The shocks, however, are identified by applying short-run contemporaneous restrictions in a vector autoregressive model based on Cholesky identification scheme. The states of the economy are determined by a threshold variable, namely output growth. The results indicate that one standard deviation shock in domestic credit leads to a significant increment in output in this economy. This effect, though, is a bit pronounced in recession than the expansion state. One standard deviation shock in domestic credit leads to around 0.8 and 0.5% increment in output in recession and expansion states at the fourth quarter and on impact, respectively. The results are also robust to an alternative proxy variable of financial development.
The Role of Trade Policy in Sustainable Tourism Inclusivity in Africa
Authors: Njoroge Msafiri
Published: November 2020

When local communities are allowed to participate fully in tourism trade activities either through supplying goods and services or direct employment in the tourism sector-inclusiveness of tourism, trade can be realized in a practical sense. Research indicates that, in most tourist destinations in Africa, the tourism trade continues to be characterized by environmental and social-cultural degradation and inadequate local community participation associated with revenue leakages and weak economic linkages. The mechanism on how tourism trade contributes inclusively on local communities' benefits such as inclusive growth and poverty alleviation remains unclear. Despite destination economies engaging in services liberalization, little evidence exists on how such trade policies have been beneficial at enhancing inclusive benefits of the tourism trade. Therefore, this chapter aims to clarify how trade policies can be employed to promote the inclusiveness of the tourism trade.
Participatory Exclusion in Community-Based Forest Management
Authors: Kosoe Enoch Akwasi , Beyuo Alexis , Addy-Morton Reginald
Published: November 2020

The inherent benefits of community participation are sometimes used by local power holders as a façade to perpetuate non-participation in the management and use of forest resources. Guided by the concept of participatory exclusion, the study assessed the perceptions of inhabitants around the Wa Community Forest Reserve (WCFR), concerning the categories of people that benefit from the forest and the factors influencing community participation in the management of the forest reserve. Data was collected from 200 households in three communities and analysed using mainly descriptive statistics and binary logistic regression. The study found that community participation in the forest reserve management is below average. Gender, age, and livelihood options of households were significant determinants of one's participation in forest reserve management. Lack of community cooperation and logistical challenges were impediments to the effective management of the forest reserve. Local authorities should therefore encourage women to co-manage the forest reserve with men and local authorities for its sustenance.
Second-Language-Writing Skills
Authors: DeCapua Sarah
Published: November 2020

In this quantitative inquiry, instead of gathering data to answer a research question, the author developed a research question based on the data she gathered. As the author explored the answers the Chinese international students in her first-year writing seminar course provided on a second language background skills assessment, she became curious about what their answers revealed about their identities. Data collected consisted of 165 English skills assessments completed by her second language writing students over four semesters, from Fall 2018 to Spring 2020. The skills assessed were speaking, listening, reading, writing, and grammar. Partial results indicated that the students assessed their speaking, listening, reading, and grammar skills as average; they assessed their writing skills as poor. The author explored the possible reasons behind the students' self-assessments and how the students' identities were expressed through their answers.
Use of Lipids, Polymers, and Peptides for Drug Delivery and Targeting to Cancer Cells or Specific Organs
Authors: Attri Sampan , Sharma Shruti , Sharma Ujjawal , Srivastava Manjita , Sonkar Subash C. , Singh Meenakshi , Bhukya Prudhvilal
Published: November 2020

Cancer has been the most deleterious disease in recent times, and unfortunately its spread is increasing. Systemic treatment with chemotherapeutics remains the conventional way of treating many cancers, despite the serious damage long-term chemotherapy can cause in healthy tissues. Many therapeutic strategies have achieved popular practical applications, but drug delivery systems still face challenges associated with safety, and this has led to the development of safer drug delivery methods composed of biocompatible substances. In this respect, lipid-, polymer-, and peptide-based drug delivery systems have been proposed as safer candidates for cancer therapy. These delivery methods are expected to as biodegradable systems with low cytotoxicity for cancer therapy. Therefore, in this chapter, the authors discuss use of lipids, polymers, and peptides as delivery vehicles for chemotherapeutic agents and their structural characteristics.
Surfactant-Based Anhydrous Nano Carrier System for Poorly Aqueous Soluble Anti-Cancer Drugs
Authors: Verma Shekhar , Chandrawanshi Nagendra , Jain Vishal
Published: November 2020

Around 40% of new chemical entities and drugs are lipophilic or poor aqueous soluble in nature. Among them many anti-cancer drugs are also consist lipophilic properties. Available poorly water soluble anti-cancer drugs are paclitaxel, etoposide, and docetaxel. To get better stability of those anti-cancer drug via encapsulation and searching suitable carrier system for the controlled release, design and development requires of anhydrous nano carrier system. However, to deliver and entrapment of these kind of anti-cancer drugs are very essential with avoidance of water free preparation to get suitable controlled release application and achieve targeting site. The primary objective of proposed chapter is to develop and design novel stable anhydrous or non-aqueous nano emulsion carrier system and provide suitable carrier system for poorly aqueous soluble anti-cancer drugs. Another important aim is to design and develop better stabilizing agent by combining different type of surfactant, co-surfactant, and co-solvent.
Beyond the Physical Library Space
Authors: Awoyemi Robert Akinade , Awoyemi Richard Oluwadolapo
Published: November 2020

This chapter examines the transformation of the physical library into a digital-oriented library environment. Space is regarded as an important feature of the physical library because the quantity of materials that can exist in the physical library is usually determined with regards to space. However, the emergence of digital technologies in the 21st century brought about the notion of digital-oriented library environment, in which a number of materials such as books, articles, and other print-based material can be converted to digital formats such as e-books, PDFs, and multimedia files which could be further stored on digital devices or uploaded online for users to access conveniently. The creation of the digital-oriented library environment has the capability of enabling librarians with innovative skills in order to meet the immediate information needs of library users. Therefore, librarians are required to understand their new roles in the 21st century and work towards creating a digital-oriented library environment.
Evaluating the Research Productivity of Pakistan in the 21st Century
Authors: Haq Ikram Ul , Faridi Rabiya Ali
Published: November 2020

The publications of scholarly communication have been considered as the driving force and the backbone for international development. The purpose of this study is to evaluate the scholarly research productivity by authors affiliated to Pakistan in all areas of knowledge. The Web of Science (WoS) database has been used to extract the records of publications produced by the authors affiliated to Pakistan and published during the 21st century from 2000 to 2019. The analysis of the retrieved documents has been conducted on the following parameters; distribution of publications by year, percentage, and annual growth rate; the top-20 most productive institutions, subject categories, collaborative countries, and preferred source publications. Findings have shown that 148,678 publications were produced by Pakistan with an average of 7,434 documents per year and 42% documents were produced during the last three years from 2017-19. COMSATS University Islamabad and Quaid-e-Azam University were found to be the most productive institutions while medicine general internal and engineering electrical electronic were found as the preferred areas of research. The examination of research showed that China is on the top, followed by United States and Saudi Arabia, but the highest citation impact in documents produced in collaboration with the authors are of Switzerland. Pakistan Journal of Botany has emerged as the most favorite source of publication. The state-of-the-art systematic research plays a significant role in the development of the country and is compulsory for sustainable developments. This study would help to re-examine the research strategies, support in the decision-making process, and further fund allocation. The result also highlights the strong and least preferred areas of research.
Development and Validation of the Social Media Self-Esteem Scale for Adolescents
Authors: Rao Devanshi Sudhindar , Kumar Aneesh
Published: November 2020

Development of the self is a vital aspect during the period of adolescence. Interaction with peers contributes to the development of various aspects of self. Due to the technological advances in today's times, adolescents interact with their peers through social media sites and portals. It is essential to study this development in light of the increasing use of social media by adolescence. Thus, the study aimed at developing an item pool to tap the construct of social media influencing self-esteem of adolescents following the procedure of tool construction. Participants included adolescents ranging between 16 to 18 years of age, who have at least one social media account for personal use. There were 110 participants for the first phase and 397 participants for the second phase of the study. The scale has eight items with the overall reliability of .7. It indicates a fitting measure of self-esteem influenced by social media, with looking-glass self theory, according to which individuals develop their self, based on their perceptions of others responses to their behaviour.
MCDM Model for Natural Gas Pressure Reducing Station Site Selection
Authors: Baldin de Lacerda Naylil Liria , Sarmento dos Santos-Neto João Batista , Martins Carolina Lino
Published: November 2020

Considering the increasing scenario of natural gas consumption, it is necessary that all agents in the chain use methods that structure decision-making and problem-solving processes. This paper proposes a multicriteria decision model to solve a site selection problem for a pressure reducing station. A natural gas distribution company was selected to test the model and the preference modeling was conducted through the flexible interactive tradeoff (FITradeoff) approach, according to the preferences of the decision maker (DM). FITradeoff's decision support system was used to assess the alternatives of the model, through the inference of the criteria scale constants. The results proved the robustness of the model and the DM evidenced consistency in its preferences. Also, the FITradeoff method demonstrated to be intuitive to apply, since a smaller effort is required from the DM and this is because the procedure does not require complete information in the scale constants elicitation process.
Analysis of Internet of Things Based on Characteristics, Functionalities, and Challenges
Authors: Khekare Ganesh , Verma Pushpneel , Dhanre Urvashi , Raut Seema , Yenurkar Ganesh
Published: November 2020

The internet of things (IoT) is transpiring technology. In the last decade, demand of IoT has been increased due to various things like the use of smart devices; increased demand for voice-based services; the concept of smart cities has been evolved; more requirements of processed data in fields of artificial intelligence and machine learning; fog computing, deep learning, etc. IoT is expected to reach the milestone of 30 billion IoT units at the end of the year 2020. Internet of things is the network of statutory things like houses, private companies, automobiles, and various objects integrated with sensors, actuators, software, electronic equipment, and internet availability that provides the facility to devices to interchange their data. The main contribution of this article is to provide state of art about the characteristics, functionalities, and challenges of the internet of things and the journey of IoT right from start to how it will make an impact on people's quality of life throughout the world in the near future.
Hyper Connectivity as a Tool for the Development of the Majority
Authors: Piaggesi Danilo
Published: November 2020

This paper explores wireless hyper connectivity and its associated costs—including ICT infrastructure—in their impact on health, education, government, and commercial applications. It analyzes the cost-effectiveness of wireless provision of access and services in underserved (especially rural) areas, examining applications around the world. A snapshot of private sector activity in Latin America and the Caribbean is presented along with government and international development organizations' efforts to promote wireless technologies in development projects. Attention is given to the policy barriers preventing the private sector from developing these technologies in the context of underserved markets, the role of government in providing universal service, and issues of spectrum allocation. Finally, recommendations are proposed for the future of multilateral development banks (MDBs) involvement in the area of wireless applications and wireless technology policy as tools for the development of emerging economies.
Development of Low Cost System for Estimating RBC, WBC Count Using Image Processing
Authors: Rajithkumar B. K.  , Shilpa D. R.  , Uma B. V.  , Mohana H. S.
Published: November 2020

Blood-related diseases are one of the most widespread and rampant vector-borne diseases in tropical countries like India. With an ever-increasing population and enormous stress on resources like land and water, new avenues open for insects like mosquitoes to breed and propagate the virus. The traditional lab method for the detection of diseases in a human's anatomy involves extracting the blood and subjecting it to various tests to count and detect the number of blood cells. An abnormally low platelet count would indicate the presence of the virus in the body. The usual method undertaken by labs all over the world is the use of the conventional chemical procedures, which may take a few hours to produce the result. The proposed system for the low cost estimating of RBC and WBC is developed using image processing techniques and canny edge detection algorithm. The obtained results are analysed and compared with the conventional methods, and results are obtained with an accuracy of 91.2.
Flexural Analysis of Epoxy Polymer Composite Reinforced With Sugarcane Fibre/Fly Ash/Carbon-Nanotube
Authors: Gopalan Venkatachalam , Vyas Rahul , Goswami Ishangiri , Shah Abhi , Pragasam Vignesh
Published: November 2020

The concept of reuse and recycle plays a very important role in using waste materials effectively. Fabrication of green composites, which adopts the reinforcement of natural and biodegradable fibres in place of synthetic fibres, is a constructive way to achieve reusability and recyclability. Hence, the sugarcane fibre, fly ash, and carbon nano tube are selected as reinforcement/filler materials for fabricating epoxy polymer matrix composite. This work is intended to investigate the flexural behaviour of the fabricated epoxy polymer composite by varying the wt. % of CNT/sugarcane fibre/fly ash. Central composite design of response surface methodology, one of the concepts of design of experiments, is used to make the experimental specimens. Further, analysis of variance is used to accomplish the influence of CNT/sugarcane fibre/fly ash on the flexural behaviour of composite. Optimized parameters are obtained to achieve the improved flexural behaviour, and the same is confirmed by the confirmation experiment.
Microstructure, Substructure and Mechanical Properties of 9CrNB Steel after Tempering
Authors: Bekeč Pavel , Parilák Ľudovít , Beraxa Pavol , Fujda Martin , Matvija Miloš
Published: November 2020

This paper deals with the analysis of microstructure and substructure of 9CrNB steel, after normalization at temperature of 1070 °C and tempering at 790 °C / 240 min. The tube was second time tempered at the following temperatures and holding times: 760 °C / 30 min (A1), 760 °C / 120 min (C1), 800 °C / 30 min (G1) and 800 °C / 120 min (I1). Microstructure after tempering consists of tempered martensite and bainite with lath morphology, while inhomogeneous redistribution of precipitates is visible. Substructure analysis of state A1 and I1 show, that a relatively large number of irregular, rod-shaped and oval carbide particles, often arranged in clusters, were precipitated at the primary original austenite grain boundaries. In case of state A1, the average size of these carbide particles is 300 nm and in case of state I1 the average size is 350 nm. A relatively large number of rod-shaped and oval shaped particles were found at the interface of the tempered martensite and bainite mainly in the form of clusters and also inside the tempered bainite with higher particle distribution. In the case of the state A1, they reached an average size of 150 nm. In some regions of substructure of the state I1, the fine carbide particles with an average size of 200 nm and coarse carbide particles with an average size of 400 nm were presented within the areas of tempered bainite. Particles were identified by EDX analysis and by selection electron diffraction. The mechanical properties after tempering were evaluated and compared with properties of P91 and P92 steel.
Comparison of Microstructure and Mechanical Properties of Additively Manufactured and Conventional Maraging Steel
Authors: Kučerová Ludmila , Jandová Andrea , Zetková Ivana
Published: November 2020

Maraging steel is an iron-nickel steel alloy, which achieves very good material properties like high toughness, hardness, good weldability, high strength and dimensional stability during heat treatment. In this work, maraging steel 18Ni-300 was manufactured by selective laser melting. It is a method of additive manufacturing (AM) technology, which produces prototypes and functional parts. Sample of additively manufactured and conventional steel with the same chemical composition were tested after in three different states – heat treated (as-built/as-received), solution annealed and precipitation hardened. Resulting microstructures were analysed by light and scanning electron microscopy and mechanical properties were obtained by hardness measurement and tensile test. Cellular martensitic microstructures were observed in additively manufactured samples and conventional maraging steel consisted of lath martensitic microstructures. Very similar mechanical properties were obtained for both steels after the application of the same heat treatment. Ultimate tensile strengths reached 839 – 900 MPa for samples without heat treatment and heat treated by solution annealing, the samples after precipitation hardening had tensile strengths of 1577 – 1711 MPa.
Structure and Properties of Bakelite Bonded Grinding Wheels
Authors: Bednaříková Vendula , Jech David , Klakurková Lenka , Čelko Ladislav , Holemý Daniel
Published: November 2020

The composition of each grinding wheel depends on the specific application, and nowadays, there are many types of grinding wheels on the market. Bakelite bonded grinding wheels are fast becoming the standard choice for grinding and finishing processes in automotive, aerospace and other special fields of industry. Increasing requirements on higher quality and lifetime push manufacture to continuous research and development in this field. From that reason, it is necessary to characterize the structure and properties of already produced commercial grinding tools. In this contribution, two in chemical composition identical bakelite bonded grinding wheels with different properties were studied. Processing parameter like compression force is the main factor resulting in either hard grinding wheel for machining soft materials or soft grinding wheel for machining hard materials. The main components of both grinding wheels are abrasive particles of brown alumina (Al2O3) and two bonding agents based on synthetic rubber and bakelite. In addition, grinding wheels contain additives, e.g. vulcanization accelerators, fillers etc. to improve functional properties of grinding wheel. Fractures and metallographic samples morphology was studied by scanning electron microscopy. Porosity of grinding wheels was estimated using image analysis. Hardness of binder and abrasive brown alumina particles was measured by Rockwell hardness test.
Possibilities for Using New Types of Additive Materials for Hardfacing
Authors: Brezina Jakub , Brezinová Janette , Viňáš Ján
Published: November 2020

The paper presents the results of the research aimed at quality determination of cladding layers for renovation of the rollers during continuous casting of steel. Four newly designed additive materials in the form of filled tubular wires of diameter 2.4 mm were evaluated. Additive materials were experimentally designed for the renovation of support rollers of the hot rolling mill. The cladding layers were applied on 31CrMoV9 material (EN 10085). Method used in experimed was submarged cladding 121 - EN ISO 4063 SAW. A specially developed flux WLDC 17 was used. The structure of cladding layers, basic mechanical propertis and their chemical composition were determined. The JOEL JSM-7000F electron microscope was used for analysis. Layers were tested under tribological conditions with pin-on-disc adhesion wear. Tests were performed on a Bruker UMT 3 device. Observation and measurement of wear traces were performed on the Sensofar PLu Neox confocal microscope.
Analysis of Causes of Baby Stroller Construction Damage
Authors: Klakurková Lenka , Juliš Martin , Gejdoš Pavel
Published: November 2020

The paper deals with the complaint between the manufacturer and the customer. The object of the dispute is a damaged stroller construction made by welding Al-Mg-Si aluminum alloy profiles with the final surface layer produced by anodic oxidation. The aim of the analysis is to identify clearly the causes of breaking the aluminum structure using fractographic and metallographic techniques.
Analysis of Corrosion Resistance of Heat Exchanger Plates Made of AISI 316L Steel
Authors: Juliš Martin , Klakurková Lenka , Gejdoš Pavel
Published: November 2020

For the corrosion resistance analysis of the heat exchanger plates (made of AISI 316L steel) the samples with visible damage was delivered. The major part of the surface damages was located at the place of "close proximity" (or surface contact) of individual plates. Some of delivered samples showed an unequal layers of sediments, which indicating a different flow velocities of operating fluid through the plates. At locations of the upper part of the plates with no sedimentation (high velocity flow), the most surface damage was detected in "near contact" areas as well as outside. On the other hand, the area of the lower part of the plates, where the sediment deposition was massive (lowest velocity flow), was observed the smallest surface damage. The results of the chemical composition analyses showed a lower amount of molybdenum and a higher amount of phosphorus in case of all samples. The contents of the key elements necessary for the corrosion resistance (chromium and nickel) were only just above the lower limit of the prescribed chemical composition interval. For detailed study of surface damage, selected defects were observed and documented using scanning electron microscopy. Localized damage showed intercrystalline failure of material with typical surface morphology degraded as a result of cavitation damage under hydrodynamic stress.
Character of Fatigue Damage under Axial, Torsional and Biaxial Loading of 316L Stainless Steel
Authors: Chlupová Alice , Poczklán Ladislav , Man Jiří , Mazánová Veronika , Heczko Milan , Kruml Tomáš
Published: November 2020

Characteristic features of fatigue damage of 316L austenitic stainless steel cyclically strained axially in tension-compression, reversed torsion and combined axial-torsional mode were studied. All loading modes resulted in the formation of persistent slip markings (PSMs). Predominantly one slip system was activated in the case of axial and torsional loading while at biaxial loading, activation of several slip systems was involved. PSMs acted as sites of multiple fatigue crack initiation. The path of subsequent crack growth at a macroscopic scale differed considerably in dependence on loading mode and applied amplitude. The hardening-softening curves and fatigue life curves were evaluated and results were compared and discussed in terms of the type of applied loading.
Detection of Early Stage of Fatigue Changes in Non-Alloy Steel Using Residual Magnetic Field Method
Authors: Antonik-Popiołek Patrycja , Głód Jacek , Jurasz Zbigniew , Juraszek Janusz
Published: November 2020

In this work, the fatigue of P265GH steel acc. to EN 10216-2 has been evaluated by measuring a residual magnetic field (RMF). During experiment the notched-specimen has been loaded with a servo-hydraulic uniaxial MTS test machine and a special magnetic sensor was applied. The measurement distribution of the residual magnetic field was performed in two axes. In the first stage of experiment the specimen was gradually loaded with quasi-static force in range of 0 to 16 kN (~ 0.7 Rm). The increase of strength of residual magnetic field was observed only from 0 to 8 kN, whereas in range 8 to 16 kN this effect was not noticed. In the second stage the controlled tensile fatigue test was performed (R = 0, Fmax = 16 kN). Up to 21k load cycles no changes to residual magnetic field were noticed. At 31k cycles the significant increase of amplitude of strength of residual magnetic field change was observed but visual inspection does not show any visible crack, while at 35k cycles crack was visible. It means that applied methodology allow to find the initiation of crack. The performed observation on SEM showed ductile fatigue of fracture.
The SEM and TEM Analysis of IN718 Alloy after Fatigue Push-Pull Loading at 700°C
Authors: Belan Juraj , Kuchariková Lenka , Vaško Alan , Tillová Eva , Chalupová Mária , Matvija Miloš
Published: November 2020

Specimens from Ni-Cr-Fe wrought superalloy INCONEL 718 were used for fatigue push-pull test at elevated temperature 700 °C. Fatigue loading was with the coefficient of cycle asymmetry R = -1. Temperature of fatigue test was chosen from two reasons; one is that limit operating temperature for this type of alloy is 650 – 700 °C due to precipitation of stable but incoherent orthorhombic Ni3Nb delta phase; the second reason for this temperature is fact that metastable body-centred tetragonal Ni3Nb gamma double prime phase starts to transform to delta phase and from that reason there is an expectation for mechanical properties decreasing due to increased volume of delta phase. For evaluation of fatigued specimens were Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) observation used. Also methods of quantitative metallography – coherent testing grids were used for evaluation of delta phase volume. Some references describe that higher volume of delta phase, mostly situated at grain boundaries, act as initiation sites for cracks and therefore decreasing mechanical properties. Employed SEM and TEM analysis confirm the increased volume of delta phase in specimens after fatigue loading but a negative influence on dynamic properties, such fatigue lifetime, for this alloy was not confirmed.
Boronizing of AISI 316L Stainless Steel Using Spark Plasma Sintering Technique
Authors: Nishimoto Akio , Kubo Tatsuki
Published: November 2020

Austenitic stainless-steel has been widely used. Although it offers excellent corrosion resistance, processability, and nonmagnetic properties, it is inferior in terms of wear resistance and hardness. Therefore, the purpose of this study is to form iron boride on an austenitic stainless-steel surface using the spark plasma sintering (SPS) method and to evaluate its properties. The SPS method was utilized because the rapid heating involved in the process reduces the processing time. AISI 316L as a sample material was boronized for 3.6 ks at 1073 – 1273 K at applied pressures of 4 MPa and 8 MPa with a powder mixture of B4C and KBF4. The Vickers hardness profile results showed that the hardness of the untreated sample was ~ 200 HV whereas that of the boronized sample was ~ 2300 HV. The wear test profile showed that the wear resistance of the boronized sample was significantly improved. Moreover, according to elemental analyses, boron diffused from the sample surface to 200 μm and 60 μm when the applied pressure was 8 MPa and 4 MPa, respectively. This indicated that boron diffused to a greater depth when the applied pressure was increased.
SnO2 Nano/Microfibers for Gas Sensors
Authors: Mudra Erika , Shepa Ivan , Kovalcikova Alexandra , Milkovič Ondrej , Dusza Jan
Published: November 2020

SnO2 is an n-type semiconductor with the band gap energy of 3.6 eV. It has been widely studied for gas sensing applications, the sensitivity of which can be easily tuned by the operating temperature. The presented paper is focused on the preparation and detailed characterization of the hollow SnO2 nano/microfibers suitable for gas detection sensors. Ceramic SnO2 fibers were produced by needleless electrospinning and followed by the calcination process. The characterization was performed by SEM, TEM, XRD, and Raman spectroscopy. The precursor PVP/SnO2 fibers had amorphous nature. The calcination of the electro spun precursor resulted in the formation of hollow crystalline fibrous structures. The formation mechanism of hollow fibers has been described. Subsequently, a homogeneous fibrous layer was created by the spin coating method for gas sensing applications.
Small Scale Plastic Yielding of Mg Alloys Assessed with Nanoindentation
Authors: Němeček Jiří , Maňák Jan , Němeček Jiří
Published: November 2020

The paper investigates deformations and plastic properties received from different material volumes and tests of magnesium samples. Small volume characteristics gained on single Mg crystals are compared to polycrystalline AZ31 alloy. Results of tests employing nanoindentation, focused ion beam milling and electron backscatter diffraction techniques are presented. Large differences were found between micro-beam testing and spherical indentation tests having the volume one order of magnitude apart. The plastic strength scaling factor was found 1.7 for the studied grain configurations and volumes.
Microstructure and Mechanical Properties of Fe-Cu-Ni Sinters Prepared by Ball Milling and Hot Pressing
Authors: Borowiecka-Jamrozek Joanna , Lachowski Jan
Published: November 2020

The main purpose of this work was to determine the effect of the powder composition on the microstructure and properties of iron-based sinters used as a matrix in diamond tools. The Fe-Cu-Ni sinters obtained from a mixture of ground powders were used for experiments. The influence of manufacturing process parameters on the microstructure and mechanical properties of sinters was investigated. Sintering was performed using hot-pressing technique in a graphite mould. The investigations of obtained sinters included: density, hardness, static tensile test, X-ray diffraction analysis, microstructure and fracture surface observations. The obtained results indicate that the produced sinters have good plasticity and relatively high hardness.
Nanomechanical Characterization of Iron Borides in Fe-Mn-B Ternary Alloys
Authors: Kirkovska Ivana , Homolová Viera , Čiripová Lucia , Petryshynets Ivan
Published: November 2020

Nanomechanical properties of iron borides, FeB and Fe2B were studied in Fe-Mn-B ternary alloys. The alloys were produced by arc melting method using high purity powders, which were subsequently annealed at temperature of 873 K and 1223 K, until fully equilibrated for a time period of 2160 hours and 1440 hours, respectively. Based on results obtained from experimental study and thermodynamic modeling of Fe-Mn-B system the solubility of Mn in these borides was determined. For the purpose of this study the influence of heat treatment temperature, as well as, the solubility of Mn in these borides on their nanomechanical properties is investigated. Nanomechanical properties, including determination of indentation modulus and hardness were measured using nanoindentation testing machine equipped with Berkovich type diamond indenter. The indentation process was carried out using an indentation depth controlled method, to a maximum depth of 500 nm.
Structural Nature of ZnAl4Cu1 Alloy Plasticity Affected by Various Technological Treatments
Authors: Longauerová Margita , Hodur Mirko , Vojtko Marek , Zubko Pavol , Glogovský Miroslav , Demčáková Mária , Matvija Miloš , Kvačkaj Tibor
Published: November 2020

The aim of this work was to analyse the microstructural nature of plasticity in ZnAl4Cu1 alloy and its dependence on the processing technology. The alloy condition was analysed after gravity casting, after forging and after ECAP processing. Two alloys with slightly different compositions were studied. For alloy A, the returnable material from a prominent Zn alloy producer was used. For B alloy input raw materials of relatively high purity were used. Tensile testing showed that in the as-cast alloy tensile strength had relatively low levels up to 211 MPa, and particularly low values of ductility only up to 2.5 % were found in B alloy, which was more polluted. By means of ECAP processing of the as-cast alloy, the tensile strength was improved by 50 % (Rm = 312 MPa). In the case of the purer A alloy the majority of samples improved to level A = 27.9 %. Forging of the as-cast alloy preserved strength on a level similar to the ECAP result, but ductility was improved to the level of 34.4 %, although alloy B had lower purity. Further significant ductility improvement was obtained through ECAP processing to A = 147 % of the as-forged alloy. The microstructure of ZnAl4Cu1 consists primarily of segregated η phase (rich in Zn) and fine eutectoid composed of η and alpha phases segregated mostly in dispersive state, but in places also in lamellar form. Close correlation between microstructure and processing method resulted from our fractographic study. In the case of ECAP processing of the forged state the finest microstructure was achieved, which was accompanied by higher plasticity and also by fine dimples of transcrystalline ductile fracture (DTDF).
Enhancement of Minority Carrier Lifetime in Ultra-High Voltage 4H-SiC PiN Diodes by Carbon-Film Annealing
Authors: Zhang Wen Ting , An Yun Lai , Zha Yi Ying , Sang Ling , Xia Jing Hua , Yang Fei
Published: November 2020

A novel process is developed for minority carrier lifetime enhancement in ultra-high 4H-SiC PiN diodes. It comprises two separate processes. Firstly, the ultra-thick epitaxial grown drift layer (200μm) covered with a protective thin carbon film is subject to a 1500°C high-temperature anneal process in Ar atmosphere for 2 hours. Secondly, a surface passivation process is adopted to reduce the surface recombination rate. μ-PCD tests show that after high-temperature anneal, the thick drift layer shows a minority carrier lifetime increase to about 1.6 μs. PiN diodes based on the novel process are fabricated and their electric characteristics are measured. Results show a low specific on-resistance of 16.3 mΩ·cm2 at 25°C and 14 mΩ·cm2 at 125 °C. Compared with simulation results, it is shown that its effective minority carrier lifetime increase to about 5μs .Our study demonstrates that the developed novel process is effective in minority carrier lifetime enhancement in ultra-voltage 4H-SiC PiN diodes.
High Temperature Annealing SP-AlN Ameliorates the Crystal Quality ofAl0.5Ga0.5N Regrowth
Authors: Yue Wen Kai , Li Zhi Min , Zhou Xiao Wei , Wu Jin Xing , Li Pei Xian
Published: November 2020

In this study, the effect of a high-temperature annealing process on AlN is investigated. The high-temperature annealing process reduces the screw dislocation density of the AlN film to 2.1x107 cm-2. The AlN surface is highly flat. Through HRXRD and Raman spectroscopy, the stress mode changes in the sputtered AlN film before and after high-temperature annealing were studied in depth. Based on the HTA-AlN template, a high-quality, high-Al composition AlGaN epitaxial wafer, with a (0002) plane rocking curve FWHM of 246 arcsec , was prepared at 1080°C The growth mode of AlGaN grown directly on the AlN template at low temperature is summarized.
Investigation of Solution-Processed Ga2O3 Thin Films and their Application in Dielectric Materials
Authors: Cai Guang Shuo , Pei Yan Li , Zhang Sheng Dong
Published: November 2020

In this paper, polycrystal Ga2O3 thin films were grown on crystal n+-Si substrates by solution process. The XRD profile revealed that monoclinic β-Ga2O3 and rhombohedral α-Ga2O3 were coexisting in the film. The solution-process Ga2O3 film exhibited an ultrahigh transmittance (>97%) to a wavelength range of 280 nm~800 nm. The optical bandgap of ~5.0 eV and breakdown field of 4.2 MV/cm of the Ga2O3 thin film was obtained. Dielectric parameters such as capacitance, dielectric permittivity and loss tangent were investigated. It was observed that these parameters have a strong dependence on frequency.
The Influence of Tri-Defects of Epitaxial Layers on the Performance of 4H-Sic Diodes
Authors: Niu Ying Xi , Song Dong Bo , Sang Ling
Published: November 2020

The triangular defect is a common defect in the 4H-SiC epitaxy, which is also one of the killer defects to the 4H-SiC devices. In this paper, the 4H-SiC epitaxial wafer was grown by chemical vapor deposition (CVD). The formation mechanism of triangular defects in silicon carbide epitaxy was analyzed, and the solutions were proposed. Then, the diodes were fabricated on the wafer, and the influence of triangular defects on the forward and reverse I-V characteristics of 4H-SiC diodes was analyzed by tracking the defects map. The results show that the presence of triangular defects can lead to the reduction of the reverse voltage by about 40%, an increase of the leakage current by four orders of magnitude, and an increase of the forward conduction resistance.
Hepatitis B Virus Core Protein Mediates the Upregulation of C5α Receptor 1 via NF-κB Pathway to Facilitate the Growth and Migration of Hepatoma Cells
Authors: Kong Fanyun , Tao Yukai , Yuan Dongchen , Zhang Ning , Li Qi , Yu Tong , Yang Xiaoying , Kong Delong , Ding Xiaohui , Liu Xiangye , You Hongjuan , Zheng Kuiyang , Tang Renxian
Published: November 2020

Purpose C5α receptor 1 (C5ΑR1) is associated with the development of various human cancers. However, whether it is involved in the development of hepatitis B virus (HBV)–related hepatocellular carcinoma (HCC) is poorly understood. We explored the expression, biological role, and associated mechanisms of C5AR1 in HBV-related hepatoma cells. Materials and Methods The expression of C5ΑR1 mediated by HBV and HBV core protein (HBc) was detected in hepatoma cells. The function of nuclear factor кB (NF-κB) pathway in HBc-induced C5AR1 expression was assessed. The roles of C5ΑR1 in the activation of intracellular signal pathways, the upregulation of inflammatory cytokines, and the growth and migration of hepatoma cells mediated by HBc, were investigated. The effect of C5α in the development of HCC mediated by C5AR1 was also measured. Results C5ΑR1 expression was increased in HBV-positive hepatoma cells. Dependent on HBc, HBV enhanced the expression of C5ΑR1 at the mRNA and protein levels. Besides, HBc could promote C5ΑR1 expression via the NF-κB pathway. Based on the C5ΑR1, HBc facilitated the activation of JNK and ERK pathways and the expression and secretion of interleukin-6 in hepatoma cells. Furthermore, C5ΑR1 was responsible for enhancing the growth and migration of hepatoma cells mediated by HBc. Except these, C5α could promote the malignant development of HBc-positive HCC via C5AR1. Conclusion We provide new insight into the mechanisms of hepatocarcinogenesis mediated by HBc. C5ΑR1 has a significant role in the functional abnormality of hepatoma cells mediated by HBc, and might be utilized as a potential therapeutic target for HBV-related HCC.
Global continuity and BMO estimates for non-Newtonian fluids with perfect slip boundary conditions
Authors: Mácha Václav , Schwarzacher Sebastian
Published: November 2020

We study the generalized stationary Stokes system in a bounded domain in the plane equipped with perfect slip boundary conditions. We show natural stability results in oscillatory spaces, i.e., Hölder spaces and Campanato spaces, including the border-line spaces of bounded mean oscillations (BMO) and vanishing mean oscillations (VMO). In particular, we show that, under appropriate assumptions, gradients of solutions are globally continuous. Since the stress tensor is assumed to be governed by a general Orlicz function, our theory includes various cases of (possibly degenerate) shear thickening and shear thinning fluids; including the model case of power law fluids. The global estimates seem to be new even in the case of the linear Stokes system. We include counterexamples that demonstrate that our assumptions on the right-hand side and on the boundary regularity are optimal.
Слабо лакунарные ортогональные системы и свойства оператора мажоранты частных сумм для подсистем
Authors: Kashin Boris Sergeevich , Limonova Irina Viktorovna
Published: November 2020

Для конечной ортогональной системы равномерно ограниченных функций установлено существование достаточно плотных подсистем со свойством лакунарности и с хорошей оценкой нормы оператора мажоранты частных сумм.