bluuebunny/crossref_metadata_2025 huggingface dataset:
TweetGST: A Web Based Systems for Sentiment Analysis and Opinion Mining for GST in Malaysia
Authors: Misyani Mohd Rafie Nurul , Dewi Varathan Kasturi , Shafenoor Amin Mohammad
Published: December 2019

Twitter is one of the most used platform for communication by people around the world. Sentiment analysis and opinion mining on twitter has become an important field of research that sees beyond the number of likes, shares and comments that users have for some topics. Nowadays, business organizations are not aware of emotional aspect of their customers and may take longer time in analyzing the market sentiment in making the necessary business decision. TweetGST is a web based system that enable business user to extract GST based tweets from Twitter as well as it helps in analyzing the tweets accordingly. TweetGST enables for trend analysis and sentiment analysis to be made. These analysis will help the business organization in order to understand customer sentiment and provide for their needs. The analyzed tweets will be used in helping the business organization to make the right decision which are recommendation for sales and stocks. Thus, TweetGST is expected to increase the revenue of the businesses.
Radiation Pattern Reconfigurable FM Antenna
Authors: Bharath Gopalakrishnan Jaya , Sabapathy Thennarasan , Jusoh Muzammil , Al-Bawri Samir , Yaasin M.N. , Nasrun Osman Mohamed , Abd Rahim Hasliza , Hafizudin Mat Mohd , Majid Huda A. , Ali Tarmizi , Abdul Wahab Yasmin
Published: December 2019

In this work, a radiation pattern reconfigurable antenna design using compact printed spiral monopoles that operates at 102 MHz is reported. The proposed antenna changes its radiation behaviour that responds towards a desired direction with the use of RF switches. The antenna is printed on a 76.6mm × 50mm PCB layer providing more than 20MHz bandwidth at -10 dB threshold and is easily fabricated with low manufacturing cost. The antenna was also simulated on 500mm × 500mm ground plane that represents the roof top of a vehicle.
Using 3D Media to Improve Short Stories Writing Skill on Junior High School Students
Authors: Khaerunnisa  , Mutiarani  , Soviana Devi Wika , Irma Sarjani Andi
Published: December 2019

The writers conducted this research as the result of field observation that found the students’ short stories writing skill are still poor. The purpose of this research is to improve short stories writing skill through three dimensional media of the students in the class IX SMPLB A Tan Miyat, Bekasi, West Java. The research method used in this research is Classroom Action Research method. This research was conducted for two months December to January for two cycles and in each cycle held in two meetings. Learning activities in short stories writing using three-dimensional media is expected that students will be easier to develop creativity and imagination in making a short story. The results of this study show that using three-dimensional media can improve the ability to write short stories. This findings of the research are the data obtained during pre-cycle is only 30%. After implementing the three dimensional media towards write short stories writing, the students’ short stories writing skill have increased. In the first cycle, the students’ short stories writing increased 50%, and on the second cycle improved into to 95%. The increasing of the students’ short stories writing skill will also improve the quality of language learning especially in the creative writing skill.
Convergence Analysis of Acceleration and Generalization of E-Learning in the Manifestation of Globalization Education Readiness 4.0
Authors: Rizki Mulyani Sitti , Ramadhanu Agung , Permata Sari Desi , Husna Arsyah Rahmatul , Sri Wahyuni Nengsih Neni
Published: December 2019

Education 4.0 is an education characterized by the use of digital technology in the learning process or known as a cyber system. In its implementation, online learning or what we know as e-learning today really determines the quality of education in every nation and country, coupled with the entry of the industrial era 4.0 which must manifest globalization learning without any limits, both in terms of time, distance, and cost. Utilization of E-learning will have a good impact on education. As a form of expression of online learning, the research team from the Putra Indonesia University YPTK Padang institution has implemented an online lecture system, facilitated by the Learning Management System (LMS) in the form of the Moodle Application. This research was conducted at Putra Indonesia University YPTK Padang with a population of all active students, while for a sample of 381 people, the sampling technique was Propotional Random Sampling using Slovin formula. As for the output of the results of this study, among others, it can be a reference material for accredited national journals and scopus. While the impact of the outcome of the research results will be referred to as a role model in online learning.
Digital Life Society Education from Punakawan History
Authors: Capellita M B , Lestari N S
Published: December 2019

This study discusses the technique of diluting the tense atmosphere in society in one case of social life. The focus of this research is traditional strategies that are still used to reduce tension in the social life of the community. The purpose of this study is to dismantle cultural heritage that is very valuable but often less understood by other people due to the use of different language and cultural codes. This study uses a qualitative research paradigm procedure. The results of the study showed that the technique of reducing tension by using the characters in the wayang stories was considered very effective. The role of the clownman becomes a figure that attracts attention. The technique used is the character, physically it must be imperfect which means inviting a smile and not in a simple social position but having a very strong influence. These characters are also very familiar with the background of the social life of the community in everyday life. This strategy is in the background of the attitude and behavior of Javanese people who do have two poles. On the one hand, Javanese people have a strong attitude, but on the other hand, they also have a very loose attitude. Javanese people use clowns which are certain characters, which are considered as strategic characters to reduce the situation of very high tension. Techniques to reduce the peak tension situation do need special expertise. This condition is indeed not easy because it has to be in all walks of life through the right language of communication.
Analysis Of Impact Android-Based Literacy Learning Media (Mpba) Application To The Development Of Skills In Interest And Literacy Of Kindergarten Students
Authors: Hartatik
Published: December 2019

Early childhood education is very important and is a very important period for children’s growth. The education process is a process for generating activities in education. Activities can produce changes in cognitive, psychomotor and affective students. This applies to every learning in the teaching and learning process. Student learning success is a learning process that is innovative and innovative. Android games are alternative software that is chosen, with the reason Android tends to be used on mobile drivers such as smartphones and tablet PCs. In the current technological development, children tend to be more familiar with various gadgets, children under five are now events exposed to various gadgets.

With the existence of Android games and supported by attractive features, it can be seen from the t-test for the purpose of the game that is obtained p value in the t test that is p = 0.000 which means that there is an influence of android learning games on child development.
Minimization of palm oil losses on sterilization process by optimization boiling pressure and boiling time
Authors: Febrina Wetri , Yusrizal  , Abrar Aidil
Published: December 2019

Optimization of boiling pressure and boiling time on palm oil processing was studied due to increasing oil palm capacity and quality by minimizing oil losses during sterilization process. We used 3 level of boiling pressure and 5 level of boiling time and analized of it’s effect to the amount of oil losses during the sterilization process. Design of Experiment Methods and Response Surface Methodology helped to see the effect of boiling pressure and boiling time to the amount of oil losses. From the study got a linier model that used to see and anylize the respons. From ANOVA test got the result that boiling time and boiling pressure significantly affected to the amount of oil losses, Optimize boiling time wa 85-90 minute with boiling pressure 2.9 bar and average of amount of oil losses from triplicate data was 1.53%.
Landslide Vulnerability in Residential Areas for Disaster Mitigation in Sawangan District, Depok City
Authors: Puspitasari Peni , Herdiansyah Herdis
Published: December 2019

Disaster occurs due to the interaction of threat factor, vulnerability and inability of the people. The lack of the capacity for decent settlement for the people has extended the use of lands for residential areas in unsuitable zone. Depok city is one of buffer zones of the capital city, Jakarta, with the population growth increasing significantly because of the pressure of the high human migration. The rapid development of an area becomes the trigger of the increasing need for lands. One of the destinations as settlement in Depok city is Sawangan district. Analyzing data technique that will be used is the descriptive analysis with the spatial approach. Map analyzing using the overlay analysis and classification. Based on the result of the overlay analysis from some maps, it shows that Sawangan district has the bumpy physical condition of an area with the slope rate of 3-8 %, population density rate of 4.001-6000 inhabitants per km2. But it has a potency leads to the land movement that is typically medium. It shows that there is a potency of human activity by building the residential-area with the high population density causes the landslide vulnerability tends to be high.
The impact analysis of flood disaster in DKI jakarta: prevention and control perspective
Authors: Wicaksono Adam , Herdiansyah Herdis
Published: December 2019

Flooding in Jakarta is a frequent disaster. Of the 2, 572 disaster events in Indonesia throughout 2018, floods and cyclones dominated more than half of the events, which made it the most frequent disaster throughout the year. This caused by various factors such as climate change, land subsidence, sea level rise and socio-economic growth. The high population in Jakarta, which reached 10.4 million due to the flow of urbanization in the past 30 years, has also added to the level of vulnerability to disaster risk. Based on secondary data that been studied from the results of previous studies, Jakarta has annual flood patterns and larger 5-year floods such as in 1996, 2002 and 2007. According to the risk assessment of flood exposure published by DKI Jakarta National Disaster Management Agency (BNPB) 10.177.570 people are potentially exposed to disasters. Physical losses reached Rp 2, 967, 433 million, and economic losses reached Rp 12, 732 million. This is certainly needed to handle mitigation with well-organized disaster management. For this reason, government intervention is needed to integrate the stakeholders who will contribute. The concept of flood disaster management that is integrated with the role of government in it is expected to be a solution to overcome the problem of flooding that occurs in Jakarta this day, besides that, community participation is also very much needed.
Designing Engineering Data Management System in Research and Development Company
Authors: Nur Muhammad , Andrawina Luciana
Published: December 2019

In the Global Era, Management Information System has become inseparable part of the company. One of the Management Information System that has been considered important in a company is Engineering Data Management System (EDMS). The role of Engineering Data Management System is to store data as well as providing a user friendly access to the data, as long as the product lifecycle appropriates with the control rules defined before. This study took a case in XYZ Company on designing Engineering Data Management System using Windchill PLM (Product Life Management) to optimize the business process. XYZ Company is a private company that works in research engineering and manufacture. This study brought out new concept using Engineering Data Management System and explains the role of EDMS in XYZ Company’s business process.
The Use of Learning Media on the Speaking Subject of Islamic Higher Educations in The Entire Central Java and Yogyakarta
Authors: Faizah Umi , Suwandi Sarwiji , Andayani  , Rahmawati A
Published: December 2019

This research aims at describing (1) the use of learning media on the speaking subject; (2) the opportunity of Islamic mission rhetoric learning media based on scientific approach on the speaking subject. The settings of this research are at Purworejo Muhammadiyah University, Purwokerto Muhammadiyah University, Surakarta Muhammadiyah University, and Yogyakarta Ahmad Dahlan University. Method of this research is a descriptive-qualitative one, namely by describing the findings found in the field obtaining through observation, interview, and questionnaire. Sample of the research consists of 247 students and 4 lecturers. The results of this research are (1) the media used on the speaking subject, among others, are rainbow kicir, doraemon pocket, telling earth, puzzle, doll, puppet, youTube, hand phone, and lap top to support the students speaking competency; (2) there is an opportunity to use Islamic mission rhetoric learning media based on scientific approach because the use of audio-visual media has not been utilized optimally, i.e. the approach and media have not been integrated.
Students’ Problem-Solving Ability in Temperature and Heat Concepts
Authors: Taqwa M. R. A. , Faizah R. , Rivaldo L. , Safitri D. E. , Aini F. N. , Sodiqin M. I.
Published: December 2019

This study aims to determine the problem-solving ability on the topic of temperature and heat. This research is a survey research. The subject of this study consisted of 118 undergraduate physics education program students’ (46 first-year students, 29 second-year students, and 43 third-year students). The research instrument consisted of 4 essay question questions. The results of the analysis show that students’ ability to solve problems about temperature and heat is still in the ‘novice’ category. In solving the problem, 13.56% of students have completed the Visual Representation stage, 68.22% of students have completed the Describe The Physics stage, 79.45% of students have completed the Plan A Solution and Excute The Plan stages, and 22.67% of students have completed the Evaluate The Answer stage. Most students only use mathematical equations without understanding their meaning.
Surface modification for creation of functional materials in molten salts and their application from cryogenic to ultrahigh temperatures
Authors: Kuznetsov S A , Dubrovskiy A R
Published: December 2019

Nowadays coatings are produced mostly by CVD, PVD methods, plasma and detonation spraying. At the same time, utilization of molten salts for coatings electrodeposition is highly attractive. Creation of a rotor cryogenic gyroscope, a biomedical material nitinol-tantalum, highly active, stable catalysts of the new generation in the form of nanostructured Mo2C coatings on molybdenum, a composite material MoSi2-MoB4 for protection of molybdenum microreactors and ultrahigh temperature Nb-Hf coatings has been discussed.
The challenges, solutions and development of high energy Ni-rich NCM/NCA LiB cathode materials
Authors: Chen Yanbin , Song Shunlin , Zhang Xuequan , Liu Yafei
Published: December 2019

In the last three decades, the successful application of lithium ion batteries (LIB) for consumer electronics has laid solid foundation for the rapid development of large format batteries for electric vehicles (EV) and energy storage systems (ESS). Up to now, in most of the commercial LIB, carbon material, e.g. graphite is used as anode material, while the cathode material changes from spinel LiMn2O4 (LMO), olivine LiFePO4 (LFP), to layer-structured material LiNi1-x-y
Co
x
Mn
y
O2, and LiNi1-x-y
Co
x
A
y
O2 (NCA), in order to get increased gravimetric and volumetric energy density. By combining the merits of the high capacity of lithium nickel oxide (LiNiO2), with the good rate capability of lithium cobalt oxide (LiCoO2), and the thermal stability and low cost of lithium manganese oxide (LiMnO2), lithium nickel cobalt manganese oxide (LiNi1-x-y CoxMnyO2, NCM) enjoys outstandingly comprehensive advantages, and turns to be the major cathode material for lithium ion batteries. One way to increase the energy densityof NCM/NCA materials is to increase the Ni content and thus lowering the Co/Mn(Al) content, another way to get high energy density is to increase the charging cut-off voltage. High energy NCM/NCA materials are confronted more challenging issues, like degradated cycle life, severe swelling upon thermal storage, and safety problems. This paper will address such issues, and put forward some feasible solutions.
Investigation of the thermal stability of titanium nickelide tantalum coating using photometric analysis of structural images
Authors: Paliy N A , Ermishkin V A , Belousov O K , Sevostyanov M A , Roshchupkin V V , Minina N A
Published: December 2019

The paper considers the thermal stability of tantalum coatings on TiNi (titanium nickelide or nitinol) used in medicine (especially in endovascular surgery) and having their own characteristics. A method is proposed to control magnetron sputtered tantalum film coatings on titanium nickelide — a method of photometric analysis of structural images (PASI).
Copolymerization of (p-2-ethoxycarbonyl)cyclopropyl styrene with methacrylic acid
Authors: Guliyev K G , Mamedli S B
Published: December 2019

By radical copolymerization the copolymer of p-(2-ethoxycarbonyl)cyclopropyl styrene with methacrylic acid has been synthesized. The copolymerization constants have been determined; Q−e parameters on Alfrey-Price and microstructure of the copolymers have been calculated. It has been revealed that the obtained copolymer has a high optical transparency and sufficiently high photosensitivity, which opens up the possibility of using it as an optically transparent polymer in optics. The conditions of preparation of optically transparent material with required physical-chemical characteristics have been developed.
Obtaining and properties of a composite membrane with a surface layer of cellulose acetate
Authors: Fazullin D D , Fazylova R D , Fazullina L I , Mavrin G V
Published: December 2019

Annotation

To reduce the concentration of dissolved salts in water treatment processes, a composite nanofiltration membrane with a surface layer of cellulose acetate on a polytetrafluoroethylene substrate was obtained. The cellulose acetate content was 17.6% by weight, upon receipt from a 10% solution of cellulose acetate in acetone. An increase in the membrane moisture capacity after modification from 0.6% to 68.5% was established, which is associated with an increase in the hydrophilicity of the membrane. The contact angle of the membrane with a drop of distilled water as a result of the deposition of cellulose acetate particles on the surface of the original membrane decreased from 130º to 53.8º. According to the results of scanning electron microscopy, it was found that the cellulose acetate particles are not located on the surface of the polytetrafluoroethylene substrate, but in the depth of its structure — in the pores, between the fibers, as a result, open pores overlap. After applying a layer of cellulose acetate to the surface of the membrane, the specific productivity of the membrane decreases by 10 times due to the accumulation of particles of cellulose acetate in the pores of the membrane. The maximum specific productivity of the modified membrane 412 dm3/m2 h, is observed when passing distilled water. The retention capacity of the membrane in terms of total salinity in the separation of tap water with an initial salinity of 323 mg/dm3 was 75%.
A universal basic for creating microsensory devices those are sensitive to changing environmental conditions
Authors: Mukhurov N I , Gasenkova I V , Zhang H , Yu G
Published: December 2019

The main advantages of alumina technology and substrates of anodic alumina with a microrelief in the bulk of the substrate as a universal basis for creating microsensor devices are presented. Microsensors of various types allow you to monitor the state of the environment. Specific examples of the development of microsensory devices for detecting humidity, gas composition in the environment, and the presence of ionizing and ultraviolet radiation are presented.
Structural Investigations of Li1.5Al0.5Ge1.5(PO4)3 glass-ceramics by Solid State NMR
Authors: Pershina S V , Dzuba M Y , Vlasova S G , Baklanova Y V
Published: December 2019

NASICON-type conductors based on LiGe2(PO4)3 are very promising lithium-conducting electrolytes for all-solid-state lithium-ion and lithium batteries. Al-doped LiGe2(PO4)3 solid electrolytes possessed higher conductivity (∼10-4 S/cm at room temperature) and stability versus metallic Li. In this paper, we present the structure study of Li1.5Al0.5Ge1.5(PO4)3 compound. Fast lithium-ion conductor Li1.5Al0.5Ge1.5(PO4)3 solid electrolyte have been obtained through glass crystallization at 820 °C during 8 h. Structural positions occupied by atoms have been examined by solid state nuclear magnetic resonance experiments. 6Li, 7Li, 27Al и 31P NMR measurements have been performed at room temperature.
An investigation of thermal stability of structure and mechanical properties of Al-0.5Mg-Sc submicrocrystalline aluminum alloys
Authors: Shadrina I S , Nokhrin A V , Chuvil’deev V N , Kopylov V I , Bobrov A A
Published: December 2019

This paper presents the results of studying the thermal stability of the grain structure, mechanical properties, and electrical resistivity of the Al-0.5wt.%Mg-xSc submicrocrystalline (SMC) alloys with varying Sc content (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 wt.%). The SMC alloys were produced by equal-channel angular pressing (ECAP). The alloys with Sc concentration above 0.3 wt.% contained submicron Al3Sc primary particles, the amount of which increased with increasing Sc concentration. High thermal stability of the SMC structure in the alloys was ensured by ECAP at 225 °C whereas the recrystallization onset temperature was 375 °C. The disintegration kinetics of the Al3Sc particles in the SMC alloys was determined by the diffusion intensity along the dislocation cores in the lattice as well as at the grain boundaries.
Crystallization and size effects in the technology of selective laser melting of metal powders
Authors: Zhukov A S , Barakhtin B K , Shakirov I V , Kuznetsov P A
Published: December 2019

A phenomenological model of the formation of phase nuclei by the vapor condensation mechanism over the metal melting zone is formulated. A multifractal analysis of the structure of steels manufactured from powders of different chemical composition by additive technology is presented. It is shown that the solidification of the molten metal is determined by the technological scheme of the selective process.
Study on Plastic Deformation Zone of Titanium Alloy
Authors: Guo P , Zhao Y.Q , Jia G.Y , Hong Q , Hou H.M , Pan H , Zhang Y.Q , Liu D.X
Published: December 2019

During the crack propagation, crack tip contains stress odd singularity and has specific yield range. As the cycling loading continuing, the crack grows in the plastic zone. So the plastic zone is crucial to crack propagation action. In this paper, the crack propagation route was observed in different microstrctures, the deformation characteristic of plastic zone was analyzed for equiaxed structure and lamellar structure. The results show that crack propagation path is more straighter in equiaxed structure than that in lamellar structure. There were more tiny cracks near the crack surface in the lamellar structure during the crack growth, which shows that lamellar structure has a bigger plastic zone during the deformation.The plastic deformation need absorb the energy, which hinders the crack propagation.
Principles of preclinical biomedical studies for biomaterial-based scaffolds intended for bone defects replacement
Authors: Sergeeva N S , Sviridova I K , Kirsanova V A , Akhmedova S A , Karalkin P A
Published: December 2019

Biomedical studies of materials precede their clinical trials. Based on our own experience and literature data, an in vitro and in vivo screening type testing algorithm for bioresorbable materials is presented, which allows one to describe cytotoxicity, cytocompatibility, cell matrix properties, biocompatibility and osteoplastic potential of the studied biomaterials.
Bone cements of calcium-magnesium phosphate and magnesium oxide
Authors: Goldberg M A , Smirnov V V , Khairytdinova D R , Krochicheva P A , Ashmarin A A , Sirotinkin V P , Baikin A S , Antonova O S , Barinov S M , Komlev V S
Published: December 2019

The new bone cements were obtained in the calcium phosphate – magnesium phosphate system. The cement powders were synthesized by precipitation method and calcium-magnesium phosphates and magnesium oxide were obtained. The cement liquids based on Na2HPO4 and NaH2PO4 characterized by pH 3.5-5.5 were used and cements phase composition, microstructure, and mechanical properties depending on pH of cement liquid were investigated. Due to the ability to form high-strength cement stone with compressive strength up to 40 MPa and setting time 10-12 minutes, these materials are promising candidates for use as the bone cements.
Low-temperature bioresorbable composite material magnesium-hydroxyapatit
Authors: Krokhicheva P , Goldberg M , Konovalov A , Ashmarin A , Baikin A , Kargin Yu , Barinov S , Komlev V
Published: December 2019

This work is focused on the development of «Magnesium (Mg) – Hydroxyapatite (HA)” composite for bioresorbable implant obtained by spark plasma sintering method (SPS). The structural-phase state of the samples was studied using the X-ray phase analysis method and scanning microscopy (SEM). It is essential to understand the mechanical behaviour of these materials: compressive strength were determined for material characterization. The obtained composite materials were investigated in the solution simulating the extracellular fluid of the human body (SBF) and NaCl solution, and there was shown the allocation of ions of calcium and magnesium and the formation of calcium-phosphate layer (CFL) on the surface of sintered samples and demonstrated. It follow that the material Mg–HA has a biocompatibility in vitro.
Melt electrospinning of polyethylene fibres for oil collection from water surface
Authors: Malakhov S N , Chvalun S N
Published: December 2019

Polyethylene nonwoven materials were obtained by the melt electrospinning. The average fiber diameter in the produced nonwovens was 5.3 μm, and the packing density was estimated as 5.2%. Wide-angle X-ray diffraction analysis showed that the polymer does not undergo significant changes in the supramolecular structure during electrospinning process: both pellets and fibers are characterized by the presence of reflections typical for the orthorhombic crystal lattice of polyethylene. The obtained materials demonstrate high hydrophobicity and oleophilicity, which allows using them as sorbents for oil spills removal. The maximum motor oil sorption capacity of the resulting nonwovens was 96 g/g.
Effect of heat treatments on the structure and properties of a small-diameter thin-walled tube of a medical nickel titanium alloy
Authors: Kashin O A , Krukovskii K V , Poletika T M
Published: December 2019

The present study examines the effect of annealing at temperatures of 300-500°C on the structure and properties of a thin-walled nitinol tube of composition Ti49.1Ni50.9 used for the manufacture of intravascular stents. Annealing temperature dependences are obtained for the martensitic transformation temperatures, the size of the structural elements of the grain-subgrain structure, phase composition, pseudo-yield stress, and ultimate strength. The effect of the Ti3Ni4 particle precipitation in aging during annealing at different temperatures on the obtained dependences is analyzed.
Modelling the parameters of powder material for the pyrometallurgical refining of platinum alloys
Authors: Pukhova O E , Levchenko S D , Shilyaeva Y I
Published: December 2019

The process of a garnishing layer formation during the pyrometallurgical refining of platinum alloys in the presence of alumina-based powder material has been investigated. The dependencies of the garnishing layer thickness on the alumina powder dispersity and the bulk density have been established. The optimal parameters of powder material have been determined based on the computational and experimental data.
Production of Li1.5Al0.5Ge1.5(PO4)3 ionic conductor from liquid-phase precursors
Authors: Kunshina G B , Bocharova I V , Ivanenko V I
Published: December 2019

The synthesis of lithium-conducting solid electrolyte Li1.5Al0.5Ge1.5(PO4)3 (LAGP) from liquid-phase precursors using available water-soluble salts (LiNO3·3H2O, Al(NO3)3·9H2O, (NH4)2HPO4) and a stable citrate [Ge(C6H5O7)3]5– or oxalate [Gе(С2О4)3]2– germanium complex was studied. Germanium complexes were obtained by dissolving the hexagonal modification of GeO2 in citric or oxalic acid. As a result of the transfer of all initial components to the solution with the formation of a true collective solution, the subsequent interaction proceeded with the formation of a single-phase LAGP product in one stage from an oxalate precursor at 650°C, from a citrate precursor — at 800°C. The synthesized LAGP was studied by XRD, TG-DSC, IR spectroscopy, chemical analysis and impedance spectroscopy. The total ionic conductivity at room temperature was 8·10–4 S/cm and 2.5·10–4 S/cm for LAGP synthesized from oxalate and citrate precursor respectively. LAGP synthesis from oxalate precursor is preferred over synthesis from citrate precursor.
Effect of 316L stainless steel powder size distribution on selective laser melting process
Authors: Du Kaiping , Li Shengfeng , Jie Shtn , Gao Xiangzhou , Yu Yueguang
Published: December 2019

The product quality of selective laser melting (SLM) is closely related to the alloy powder size distribution. The small voidage of fine-sized alloy powder bed is beneficial to improve the density of SLM product. While, the fine-sized alloy powder would result in the poor powder spreading uniformity in the SLM equipment, which leads to the formation of holes in the SLM product. In this work, the 316L stainless steel powder was prepared by a vacuum atomization furnace and sieved into a coarse-sized distribution and a fine-sized distribution. Then, the coarse-sized powder and the fine-sized powder are mixed according to different ratios. The results show that, under the condition of same SLM parameters, the density and strength of the SLM sample gradually decrease, with the increasing amount of fine-sized powder. The main reason for this phenomenon is that the fine-sized powder, with the large specific surface, is easy to bond with the coarse-sized powder. It reduces the fluidity of powder, resulting in the pores and cracks during the SLM layering process. Furthermore, the addition of fine-sized powder to the coarse-sized powder results in a decrease in the elongation of SLM sample. However, with the increase of the addition amount of the fine-sized powder, the residual stress is released due to the formation of a large number of cracks and pores, so that the elongation of SLM sample is slightly increases.
Experimental and simulation study for rewelding defects during the flow process of Semi-solid die casting
Authors: Defu Li , Chen Song , Li Daquan
Published: December 2019

Semi-solid die casting process due to its advantages of compact process, high performance and low cost is widely applied in automobile, communication and other industries for the preparation with high performance aluminum alloy castings. Compared with liquid metal melt, the filling behavior is laminar flow for semi-solid metal melt with higher apparent viscosity. In the process of semi-solid die casting, the semi-solid metal melt from different directions came together, it will lead to “rewelding” defects if with insufficient fusion or uneven slurry state. In this paper, the formation reasons and forms of flow “rewelding” defects are analyzed. By numerical simulation and experimental analysis, the flow state of semi-solid metal melt at the junction of filling frontier is represented, and the state of “rewelding” defect is characterized. The effect of eliminating defects is analyzed by modifying the mold structure, such as redesigning overflow and venting systems at the confluence position. The results show that the microstructure of the “rewelding” defects in the confluence position of the semi-solid metal melts is the segregati12on of solid and liquid phase, gas, oxidation inclusions and other defects. Different semi-solid die casting process will affect the flow state and defect size at the location of different semi-solid metal melt coming together. By means of the process control and the mold structure optimization, “rewelding ” defects can be removed from the product cavity. The aluminum alloy semi-solid die-casting products with high performance are obtained finally.
Magnesium vapor reduction of complex double compounds of molybdenum with tungsten
Authors: Kolosov V N , Miroshnichenko M N , Prokhorova T Yu
Published: December 2019

The process of obtaining powder of the Mo-W alloy by magnesium vapor reduction of MgW
x
Mo1–x
O4 and CaW
x
Mo1–x
O4 oxide compounds (x = 0.3) with a residual inert gas pressure of 2-20 kPa in the temperature range 700-800°C was investigated. Argon or helium was used as an inert gas. Powders of Mo-W alloy with a specific surface area of up to 20 m2g-1 were obtained. When both types of compounds were reduced at a residual pressure in the reactor of more than 5 kPa, spatial separation of the reaction products was observed with removal of magnesium oxide from the reaction zone.
Measurement on the thermal barrier ability of ceramic coatings in a flame thermal shock tester
Authors: Yuan Kang , Hou Weiao , Peng Haoran
Published: December 2019

Ceramic materials are widely used at high temperatures due to their low thermal conductivity. Thermal barrier coatings (TBCs) have been applied in hot sections in industrial gas turbines and air engines. The measurement of the thermal barrier ability of the TBCs is very important for coating property evaluation, that can be done in hot gases with temperature gradient through the coatings. In this study, a flame thermal shock tester was used for such investigation. Thick TBC, containing a MCrAlY bond coat and a YSZ top coat, was sprayed onto a superalloy substrate by air plasma spray (APS) process. In the test, hot flame impacted on the top coat surface with the temperature controlled by an infrared thermometer. A thermocouple was attached onto the backside of the substrate to measure the backside temperature. Therefore, the temperature gradient in the TBC can be evaluated. The thermal barrier ability of the TBCs in different back cooling rate was studied.
Oxidising and carburising catalyst conditioning for the controlled growth and transfer of large crystal monolayer hexagonal boron nitride
Authors: Babenko Vitaliy , Fan Ye , Veigang-Radulescu Vlad-Petru , Brennan Barry , Pollard Andrew J , Burton Oliver , Alexander-Webber Jack A , Weatherup Robert S , Canto Barbara , Otto Martin , Neumaier Daniel , Hofmann Stephan
Published: December 2019

Hexagonal boron nitride (h-BN) is well-established as a requisite support, encapsulant and barrier for 2D material technologies, but also recently as an active material for applications ranging from hyperbolic metasurfaces to room temperature single-photon sources. Cost-effective, scalable and high quality growth techniques for h-BN layers are critically required. We utilise widely-available iron foils for the catalytic chemical vapour deposition (CVD) of h-BN and report on the significant role of bulk dissolved species in h-BN CVD, and specifically, the balance between dissolved oxygen and carbon. A simple pre-growth conditioning step of the iron foils enables us to tailor an error-tolerant scalable CVD process to give exceptionally large h-BN monolayer domains. We also develop a facile method for the improved transfer of as-grown h-BN away from the iron surface by means of the controlled humidity oxidation and subsequent rapid etching of a thin interfacial iron oxide; thus, avoiding the impurities from the bulk of the foil. We demonstrate wafer-scale (2″) production and utilise this h-BN as a protective layer for graphene towards integrated (opto-)electronic device fabrication.
Effects of Q&T parameters on phase transformation, microstructure, precipitation and mechanical properties in a PS-30Cr2Nb pipeline steel
Authors: Guan Jisheng , Yuan Qing , Xiong Zhiqiang , Zhang Qingxiao , Xu Guang
Published: December 2019

The heat treatments with different quenching and tempering temperatures were conducted to clarify the effects of Q&T (quenching and tempering) parameters on phase transformation, microstructure, precipitation, mechanical properties in a PS-30Cr2Nb pipeline steel. Results indicate that the optimum property of tensile strength of 892 MPa and elongation of 19.17% was obtained at a low quenching (950 °C) and low tempering temperature (570 °C). Finer prior austenite grains and carbides contributed to the higher strength. Besides, the content of coarsening carbides increased with tempering temperature and quenching temperature. The increased content of coarsening carbides is responsible for the deteriorative comprehensive performance. In addition, Fe3C particle was gradually substituted by the alloy carbides with the proceeding of tempering by the dynamic assignment of elements.
Heavy metal free thermal stabilizing-flame retarding modifier for plasticized poly(vinyl chloride)
Authors: I Al-Mosawi Ali , Marossy Kálmán
Published: December 2019

Our research aimed to find a new material that can be an efficient heavy metal free flame retardant for plasticized poly(vinyl chloride) comparable to the conventional flame retardants. One of these extraordinary materials is Oxydtron using as an admixture for concrete. Oxydtron showed unexpected efficiency as a flame retardant agent and an excellent heat stabilizer as well. Limiting oxygen index (LOI), static heat stability, Congo-red, and differential scanning calorimetry (DSC) were carried out. The thermal tests proved that Oxydtron is suitable to improve plasticized poly(vinyl chloride) performance at high temperatures applications in terms of flame retarding and thermal stability. Therefore, the positive result obtained by the addition of Oxydtron is reducing of plasticized poly(vinyl chloride) flammability by 25.23%, and increasing its thermal stability as well.
Material characterization and unconventional machining on synthesized Niobium metal matrix
Authors: Sivakandhan C , Babu Loganathan Ganesh , Murali G , Suresh Prabhu P , Marichamy S , Sai Krishnan G , Pradhan Raghuram
Published: December 2019

The Purpose of this work is to develop a niobium based metal matrix alloy through sintering based powder metallurgy technique. The 2, 4 and 6 weight percentage of Titanium Carbide (TiC) is added to the alloy. Various material properties such as hardness, tensile strength, impact strength and density are measured after the addition of TiC particle. The characterization, microstructure and particle size of the developed metal matrix are learnt through Scanning Electron Microscope (SEM) and Energy Dispersive Analysis of x-rays (EDAX). Finally, the synthesized niobium metal matrix is machined by unconventional machining processes namely Ultrasonic Machining (USM) and Laser Beam Machining (LBM) processes. The various input and output parameters have been considered for this experimental work. The most influential parameters on Material Removal Rate (MRR) and Surface Roughness (SR) are found by Analysis of variance. The systematic evaluation of optimal parameters of MRR and SR are carried out by using taguchi approach.
DFT-investigation on anisotropy degree of electronic, optical, and mechanical properties of olivine ZnRE2S4(RE = Er, Tm) compounds
Authors: Batouche M , Seddik T , Uğur S , Uğur G , Messekine S , Vu Tuan V , Khyzhun O Y
Published: December 2019

Using PP-APW method the electronic, optical and mechanical anisotropy of ZnRE2S4(RE = Er, Tm) olivine compounds was investigated. The calculated unit cell parameters are in good agreement compared to the experimental ones. In addition, the study of electronic properties reveals that ZnEr2S4and ZnTm2S4are semiconductors with a direct bandgap of about 2.37 eV and 2.35 eV, respectively. The optical constants such as refractive index, reflectivity, and absorption coefficient have been calculated and analyzed. These constants show a clear anisotropy in the UV region for both compounds caused by the different electron polarizability inx−,y− andz−direction. Moreover, the elastic constants are estimated for the first time for ZnEr2S4and ZnTm2S4indicating that the compounds are mechanically stable and reveal ductility behavior. The direct bandgap, optical absorption, and mechanical stability make ZnEr2S4and ZnTm2S4promising candidates for optoelectronic application.
Characterization, corrosion and failure strength analysis of Al7075 influenced with B4C and Nano-Al2O3 composite using online acoustic emission
Authors: Emmy Prema C , Suresh S , Ramanan G , Sivaraj M
Published: December 2019

This paper aims to establish the mechanical, corrosion and failure analysis using online acoustic emission of Al7075 alloy, Al7075-B4C composite and Al7075- B4C-Al2O3 hybrid composite with different Boron Carbide (B4C) content of 5, 10, 15 & 20% and Nano Aluminium Oxide (Al2O3) content of 2% on a weight basis with the high energy stir casting method. The casted samples have been characterized by x-ray Diffraction (XRD), Thermo gravimetric analysis (TGA/DSC), Energy Dispersive Spectrum (EDS), and Scanning Electron Microscope (SEM). In case of hybrid composite, the hardness and the tensile strength decrease when the content of Al2O3 increases. However, in the present research, the addition of B4C with nano Al2O3 particles in certain proportions has increased the hardness and tensile strength. In addition, the tensile fractographs of the specimens were analysed using SEM. Acoustic Emission (AE) method was used for monitoring the acoustic energy that are released at the time of deformation process and early crack detection. The influence of the volume fraction of the B4C particulates on the microstructural and corrosion characteristics of Al7075- B4C with nano Al2O3 metal matrix composites (MMCs) was also studied. It has been observed from the literature that the direct strengthening of composites occurs due to the presence of hard ceramic phase, while the indirect strengthening arises from the thermal mismatch between the matrix alloy and reinforcing phase during solidification. Based on the database for material properties, the application area of HAMCs has been proposed in the present review. The effects of nanomaterial dispersion in the metal matrix and the formation of interfacial precipitates on these properties are also addressed. Particular attention is paid to the fundamentals and the structure–property relationships of such novel Nano composites.
Solar-driven steam generation on nitrogen-doped graphene in a 2D water path isolation system
Authors: Chen Yuchao , Sha Changchang , Wang Wenju , Yang Fufeng
Published: December 2019

Solar-driven steam generation using photothermal materials is a green and promising approach to address clean water scarcity. In this work, the graphene oxide(GO) was synthesized by an improved Hummers method, and then GO was reduced by hydrothermal method and modified with nitrogen, called as NRGO. Then, we performed UV-VIS-NIR, XRD, Raman, FTIR and SEM characterization. In order to reduce the heat loss of bulk working liquid and improve the solar-to-heat conversion efficiency, the isolation system with 2D water path was used. The efficiency test of steam generation was performed under the solar intensity of 1000 Wm−2 for 1 h, and the photothermal conversion efficiency of reduced graphene oxide (RGO) and nitrogen-doped graphene (NRGO) was 73% and 87%, respectively. It was found that NRGO owned better solar absorption efficiency, lower thermal conductivity and porosity. NRGO was combined with insulated isolated system which can reduce the heat loss of bulk water, to improve photothermal conversion efficiency.
The prominent charge-transfer effects of trinuclear complexes with nominally high nickel valences
Authors: Yamagami K , Imada S , Yamanaka K , Yaji T , Tanaka A , Kouno M , Yoshinari N , Konno T , Sekiyama A
Published: December 2019

Recently synthesized Rh-Ni trinuclear complexes hexacoordinated with sulfur ions, 3-aminopropanethiolate (apt) metalloligand [Ni{Rh(apt)3}2](NO3)
n
(n = 2, 3, 4), are found to be chemically interconvertible between the nominal Ni2+ and Ni4+ states. In order to clarify the origins of their interconvertible nature and the stability of such a high oxidation state as the tetravalency from the physical point of view, we have systematically investigated the local 3d electronic structures of [Ni{Rh(apt)3}2](NO3)
n
by means of soft x-ray core-level absorption spectroscopy (XAS). The experimental data have been reproduced by the single-site configuration-interaction cluster-model simulations, which indicate that the charge-transferred configurations are more stable than the nominal d-electron-number configuration for n = 3, 4 leading to the prominent charge-transfer effects. These are also supported by S K-edge XAS of [Ni{Rh(apt)3}2](NO3)
n
. Our results imply that the found charge-transfer effects have a key role to realize the interconvertible nature as well as the stability of the high oxidization state of the Ni ions.
Light-induced charge transfer at the CH3NH3PbI3/TiO2 interface—a low-temperature photo-electron paramagnetic resonance assay
Authors: Mantulnikovs Konstantins , Szirmai Péter , Kollár Márton , Stevens Jeremy , Andričević Pavao , Glushkova Anastasiia , Rossi Lidia , Bugnon Philippe , Horváth Endre , Sienkiewicz Andrzej , Forró László , Náfrádi Bálint
Published: December 2019

The performance of organic–inorganic metal halide perovskites-based (MHPs) photovoltaic devices critically depends on the design and material properties of the interface between the light-harvesting MHP layer and the electron transport layer (ETL). Therefore, the detailed insight into the transfer mechanisms of photogenerated carriers at the ETL/MHP interface is of utmost importance. Owing to its high charge mobilities and well-matched band structure with MHPs, titanium dioxide (TiO2) has emerged as the most widely used ETL material in MHPs-based photovoltaic devices. Here, we report a contactless method to directly track the photo-carriers at the ETL/MHP interface using the technique of low-temperature electron paramagnetic resonance (EPR) in combination with in situ illuminations (Photo-EPR). Specifically, we focus on a model nanohybrid material consisting of TiO2-based nanowires (TiO2NWs) dispersed in the polycrystalline methylammonium lead triiodide (MAPbI3) matrix. Our approach is based on observation of the light-induced decrease in intensity of the EPR signal of paramagnetic Ti3+ (

S
=
1

/

2

) in non-stoichiometric TiO2NWs. We associate the diminishment of the EPR signal with the photo-excited electrons that cross the ETL/MHP interface and contribute to the conversion of Ti3+ states to EPR-silent Ti2+ states. Overall, we infer that the technique of low-temperature Photo-EPR is an effective strategy to study the transfer mechanisms of photogenerated carriers at the ETL/MHP interface in MAPbI3-based photovoltaic and photoelectronic systems.