bluuebunny/crossref_metadata_2025 huggingface dataset:
A Collaborative Decision Support System Framework for Vertical Farming Business Developments
Authors: De Oliveira Francis J. Baumont , Ferson Scott , Dyer Ronald
Published: November 2020

The emerging industry of vertical farming (VF) faces three key challenges: standardisation, environmental sustainability, and profitability. High failure rates are costly and can stem from premature business decisions about location choice, pricing strategy, system design, and other critical issues. Improving knowledge transfer and developing adaptable economic analysis for VF is necessary for profitable business models to satisfy investors and policy makers. A review of current horticultural software identifies a need for a decision support system (DSS) that facilitates risk-empowered business planning for vertical farmers. Data from the literature alongside lessons learned from industry practitioners are centralised in the proposed DSS, using imprecise data techniques to accommodate for partial information. The DSS evaluates business sustainability using financial risk assessment. This is necessary for complex/new sectors such as VF with scarce data.
A Study of Feature Selection and Dimensionality Reduction Methods for Classification-Based Phishing Detection System
Authors: Singh Amit , Tiwari Abhishek
Published: November 2020

Phishing was introduced in 1996, and now phishing is the biggest cybercrime challenge. Phishing is an abstract way to deceive users over the internet. Purpose of phishers is to extract the sensitive information of the user. Researchers have been working on solutions of phishing problem, but the parallel evolution of cybercrime techniques have made it a tough nut to crack. Recently, machine learning-based solutions are widely adopted to tackle the menace of phishing. This survey paper studies various feature selection method and dimensionality reduction methods and sees how they perform with machine learning-based classifier. The selection of features is vital for developing a good performance machine learning model. This work is comparing three broad categories of feature selection methods, namely filter, wrapper, and embedded feature selection methods, to reduce the dimensionality of data. The effectiveness of these methods has been assessed on several machine learning classifiers using k-fold cross-validation score, accuracy, precision, recall, and time.
Impact of Intellectual Capital and Total Risk Management on Bank Performance
Authors: Islam Md. Saiful , Rahman Md. Azizur , Anam Sayedul
Published: November 2020

Bank performance is treated as a pivotal indicator of total economic stability of a country. Generally, the intellectual capital measurement is the study of the impact of intellectual capital on the banks performance and gives some proposal aiming to improve the efficiency of the banking industry. The TRM encompasses all the activities that affect its risk domain. Risks are generally defined by the adverse impact on profitability of several distinct sources of uncertainty. The prime focus of this study is to find out the relationship among intellectual capital, total risk management, and the performance of Bangladeshi listed banks. The result shows that bank performance has no statistically significant relationship with total risk management of the sample banks and level of investment on intellectual capital. Likewise, the findings of the study are as comparable with some other studies where the authors have found similar and/or different economic characteristics.
A Proof of Concept of a Business Intelligence Platform to Support the Decision-Making Process of Health Professionals in Waiting Lists
Authors: Esteves Marisa , Esteves Márcia , Abelha António , Machado José
Published: November 2020

In the last years, the increase of the average waiting times in waiting lists has been an issue felt in several health institutions worldwide. Therefore, this problematic situation creates the need to define and implement new administrative measures in order to improve the management of these organizations. In this context, this research project arose in an attempt to support the decision-making process in waiting lists, namely medical appointments and surgeries, in a hospital located in the north of Portugal. Hereupon, a pervasive business intelligence platform was designed and developed using recent technologies such as React, Node.js, and MySQL. The proposed information technology artifact allows the efficient and easy identification in real-time of average waiting times outside the outlined patterns. Thus, the aim is to enable the reduction of average waiting times through the analysis of business intelligence indicators in order to ensure patients' satisfaction by taking necessary and adequate measures.
Experimental Investigation on the Effect Due to Mould Vibrations on Mechanical and Metallurgical Properties of Aluminum Alloy (A-1050)
Authors: Bobba Sujith , Mukkollu Sambasiva Rao , Leman Z. , Bachina Harish Babu
Published: November 2020

In the current research work performed, the consequences caused in the casting aluminum alloy specimen due to mechanical mould vibrations are examined. Mould vibration throughout the casting provides decreased rate of shrinkage, good morphology, surface finish and lesser probability of hot tear. In this research work, the effect of mould vibration during solidification of Aluminum A-1050 alloys for dissimilar values of wavelengths at a permanent pouring temperature has been investigated to understand the modification in microstructure and mechanical properties after casting. The Al A-1050 casting has been made in a metal mould with different vibrations. The frequencies are varied from 15Hz to 50 Hz during the casting process. A casting has been made with different vibration as well to compare the results of castings with vibration frequencies. The experimental outcomes exhibited substantial grain refinement and significant increase in tensile strength and hardness of the castings with mechanical mould vibration during the duration and after solidification.
The Effectiveness of Credit-to-GDP Gap as a Leading Indicator of Banking Crises in India
Authors: Akhter Javaid , Tandon Deepak , Kulshreshtha Gaurav
Published: November 2020

As per the 15th progress report on adoption of the BASEL regulatory framework, published in October 2018 by Basel Committee on Banking Supervision, 26 member jurisdictions now have final rules in force for CCCB. In India, the final rules on CCCB came into force from 5th Feb, 2014; however, the buffer has not been activated by RBI till now as in its assessment, the Credit to GDP gap and other indicators currently do not warrant activation of the countercyclical capital buffer (CCCB). The Basel III regulatory framework for more resilient banks and banking systems, released in December 2010, had introduced the CCCB aimed at strengthening banks defense against the build-up of systemic vulnerabilities. The CCCB is a pre-emptive measure that requires banks to build-up capital gradually as imbalances in the credit market develop. The primary objective of CCCB is to avoid any banking industry stress resulting from wide fluctuations in the credit cycle using the credit-to-GDP gap. In doing so, it raises the cost of capital for banks resulting in moderation of credit demand as well as dissuasion of banks from participating in binge credit growth during the buildup phase itself. The authors have calculated the credit-to-GDP gap (which has been accepted as the main Indicator) for India using the available data and conclude that the buffer guide has historically worked as a reliable EWI in the Indian context. The authors have also concluded that while CCCB is an instrument to protect banks from the bust phase of the financial cycle, it is not an instrument to manage the financial cycle, even if it may potentially have a smoothing impact. An important implication of implementing CCCB using the credit-to-GDP gap as the main indicator for banks and EMEs is that it may hinder beneficial financial deepening, if it is used to actively manage the financial cycle. The authors recommend including the attribution of the Credit-to-GDP GAP w.r.t., the changes attributable to GDP growth, as well as attributable to changes in credit growth in the decision making process to activate CCCB.
A Study of the Antecedents of e-WOM in Social Commerce Platform
Authors: Choi Youngkeun
Published: November 2020

The purpose of this study is to show how electronic word of mouth attracts users and drives purchases. By presenting the concept of electronic word of mouth in a variety of ways that provide different experiences, the author develops a model that explores the effects that explain the antecedents of electronic word of mouth and consumers' intention to purchase in social commerce. For this, this study surveys 352 consumers using social commerce in Korea and analyzes the data using AMOS 24. In the results, first, argument quality, source credibility, source attractiveness, and source perception increase the electronic word of the consumer. Second, consumer electronic word of mouth increases his or her purchase intention. Finally, argument quality and source perception origin among the pioneers of the electronic word-of-mouth of the consumer increases his or her purchase intention through the electronic word of mouth. This study is the first one to investigate the reciprocal engagement characterized by electronic word of mouth.
A New Approach for Solving the Flow Shop Scheduling Problem Through Neural Network Technique With Known Breakdown Time and Weights of Jobs
Authors: Kumar Harendra , Giri Shailendra
Published: November 2020

This paper considers a flow shop scheduling problems of n jobs on m machines involving processing times and weights of jobs with the major constraint as breakdown times of the machines. In this paper a new procedure is provided to obtain an optimal job sequence with the objective of minimize the makespan and mean weighted flow time by using neural network technique. To illustrate the proposed method procedure, a numerical example is given. The effectiveness of the proposed method is compared with many problems which are taken from different papers. This paper also provides a comparison of our proposed method with the existing methods in literature.
Inclusion Engineering in Structural Steels with Enhanced Machinability
Authors: Pytel Stanislav
Published: November 2020

In the first part of this paper inclusion morphology and factors influencing machinability of structural steels are shortly discussed. In the experimental part of this work the effect of calcium addition on the inclusion morphology transformation and the machinability Bindex (according to Volvo standard) for several grades of structural steels are presented.
The Influence of Secondary Phase on Impact Toughness of Alloyed Iron Aluminides
Authors: Švec Martin , Hotař Adam , Vodičková Věra , Keller Vojtěch
Published: November 2020

The microstructure and fracture surfaces were investigated for five Fe3Al – based iron aluminides doped by different alloying elements (Nb, Zr + C, Cr) or without addition. Generally, iron aluminides are considered as brittle material at room temperature, therefore the type and distribution of secondary phases affect the fracture behaviour. The influence of present secondary phase particles on impact toughness at room temperature was evaluated in comparison to binary alloy. The type and the volume fraction of particles affect the value of impact toughness significantly – these values decrease with increasing volume fraction of precipitates. On the other hand, the solid solution strengthening improves impact toughness.
On the Surface Welding of Pearlitic Rails: The Control of Dilution and Microstructure
Authors: Suwanpinij Piyada , Hübner Martin , Choeychom Panita , Thonondaeng Thanaporn , Suksawat Bandit , Kumma Parinya , Lothongkum Gobboon
Published: November 2020

This work studies the surface welding parameters for a practical repair for pearlitic rail grades: R260 and R350HT. A filler metal containing low carbon (0.15 %), high silicon (0.5 %) and nickel (2.5 %), self-shielded flux-core welding electrode (FCAW-S) is the candidate in order to ensure the preferable carbide-free bainite. The film-like morphology of the retained austenite is reported to promote the wear resistance and is ensured by silicon and nickel. The effect of preheat temperature and dilution on the microstructure and resulting hardness can be concluded. Too high dilution, as a result of high current and travel speed, and the reheating during the welding of the second layer can result in martensite formation and too high hardness. Proper control of the dilution ensures satisfactorily hardness and avoids martensite formation.
Fractography of Additively Manufactured Titanium Alloy: Influence of Post-Processing Treatment
Authors: Roudnická Michaela , Vojtech Dalibor
Published: November 2020

Additively manufactured metals have their specifics which influence their performance. Based on fractography, these specifics are depicted in this paper on the example of titanium alloy Ti6Al4V manufactured by selective laser melting (SLM). While very fine microstructure contributes to high strength during static loading, dynamic loading is impaired by rough as-built surface and internal defects. With post-processing treatment, these undesirable features can be removed or significantly reduced. To densify the material, hot isostatic pressing (HIP) closing internal voids is commonly used. Rough surface can be removed by machining or other operations, including chemical treatment. The influence of HIP and machining on fatigue failure are in the focus of this paper.
The Copper-Arsenic Eutectic and the Cu3As Phase
Authors: Haubner Roland , Strobl Susanne
Published: November 2020

In ancient bronze ingots Cu3As was observed beside other impurities like Sb. Moreover, the Cu-As bronzes were studied concerning the decrease in As during melting respectively remelting. To verify the microstructure and hardness of the eutectic and Cu3As phase appropriate mixtures were produced by melting pure Cu and As. The eutectic point in the Cu-As system is at 685 °C and 20.8 wt. % As and the Cu3As phase with 29.56 wt. % As melts at 827 °C. In the sample´s core the microstructure is a homogeneous eutectic, but near the surface it becomes hypoeutectic, i.e. an As loss took place. The lamella thickness of the eutectic was in the range of about 1 µm. The sample with a Cu3As composition showed a proeutectic microstructure with mainly Cu3As and a small amount of eutectic. In the large Cu3As crystals twin lamellae were observed. Additionally, by Vickers indents new twins were introduced. The microhardness of the Cu-As solid solution is 78 HV0.025, of the eutectic 125 HV0.025 and of the Cu3As phase 158 HV0.025. On some surfaces of the Cu3As sample a Cu-rich phase was observed. We are not able to explain this phenomenon, but it is definitively no “inverse segregation”.
Surface Chemistry-Based Surface Defects Situated on Steel Strips Edges
Authors: Gabániová Mária
Published: November 2020

Two thirds of all examined defect cases present on rolled steel strips appeared to be chemical in nature. They are characterized by a modification in surface chemistry. Chemistry-based defects on the steel strips can vary in composition and generally consist of reaction products with the steel substrate. First big category of widely occurring chemistry-based defects is corrosion or oxidation, second contamination with alien matter and third defect category is related to carbon sediments. A number of different surface chemistry-based defects are related to annealing process. Common problem, that occurs in communication is, that identical defects are often indicated by different names and identical names are given for different defects. In the present study an overview including possible causes of three types of the continuous chemistry-based defects situated on the steel strip edges, that appeared to be the same at first glance, is presented: carbon edge deposit, low reflectivity band and annealed border.
Metallographic Documentation of the Degradation of Iron and Nickel Based Alloys in HCl and H2S Containing Environments, between 480 – 680 °C
Authors: Schmid Alexander , Mori Gregor , Haubner Roland
Published: November 2020

Corrosion behavior of the alloys 1.7386 (P9), 1.4462, 1.4841, 1.4959 (Alloy 800HT) and 2.4816 (Alloy 600) was tested for 24, 72 and 240 h between 480 – 680 °C. The testing gas atmosphere contained 3.8 vol. % HCl, 200 ppm H2S and CO, CO2 and N2. It simulated conditions present in a thermal cracking process for post-consumer plastics. Samples were analyzed by metallography, SEM/EDX and XRD after corrosion experiments. Additionally, their mass loss during the test was evaluated. A multilayered structure of corrosion products grew on the samples during the corrosion experiments. The composition of the corrosion products depended not on the material, but on the testing temperature. At 680 °C chromium sulphide formed the outer layer, followed by a chromium oxide layer. Below these two layers a chlorine containing layer was observed. At 480 °C mainly nickel sulphide was detected, besides chromium oxide and iron- and chromium chloride. Especially at higher testing temperatures FeCl2 was not observed directly on the samples, but as colorless crystals at the colder parts of the testing equipment. At 680 °C the mass loss of the samples decreased with increasing nickel content. However, this effect changed entirely at lower testing temperatures. At 480 °C 1.7386 and 2.4816 showed nearly the same mass losses.
Estimating of the Size of the Maximum Non-Metallic Inclusions in Martensitic Steels and their Influence on Fatigue Properties
Authors: Kasl Josef , Matějová Miroslava , Špirit Zbyněk
Published: November 2020

Fatigue cracks can start from non-metallic inclusions in the subsurface zone at low stress amplitude level and high number of cycles. This phenomenon was observed mainly at high strength steels and parts with hardened surface zone. Fatigue strength of steel can be then estimated on the basis of hardness and maximum size of defect/inclusions measurements. Many inclusions rating methods exist, some of which have been adopted as the standards. However, “standard” methods for characterization of inclusion content are not convenient for assessment of their influence on fatigue strength of materials. This contribution deals with assessment of maximum sizes of inclusions in three types of martensitic steels used for production of rotating blades of steam turbines (Böhler T552, Böhler T671, and MLX 17) using extreme value statistics methods. Murakami´s concept of √AREAmax parameter and procedure according to ASTM E2283-08 were applied. Results were compared one another and also with the result of standard methods, too. Founded parameters were used for calculation of expected limit of the fatigue strength and compared with results of fatigue test of these steels.
Characterization of Microstructure of Crept Samples of Dissimilar Weld Joint Using Standard and Advanced Electron Microscopy Techniques
Authors: Kasl Josef , Jandová Dagmar , Mikmeková Šárka , Ambrož Ondřej
Published: November 2020

Conventional long-term creep test (CCT) to the rupture and so called accelerated creep test (ACT) of the dissimilar weld joint made of FB2 and F martensitic steels and of the base materials were carried out at temperatures ranging from 550 °C to 650 °C in the stress range from 70 to 220 MPa. Assessment of microstructure development and changes of hardness was correlated with the creep strength. During creep at temperatures above 575 °C Laves phase precipitated in all parts of the weld joint and especially in the heat affected zones. Coarse Laves phase particles and their clusters with chromium carbides served as nucleation centers for cavities. As the fine grained heat affected zone of F steel was the softest part of the weld joint, many cavities originated and cause failure of samples. The aim of this paper is to compare results and possibilities of the “standard” methods and advanced scanning electron microscopy performed by instrument equipped with a concentric backscatter electron detector (CBS). Filtering of the signal enables improving and/or diminishing of selected type of contrast caused by various types of particles of secondary phases. The images were used as an input data for image analysis and developments of microstructures during CCT and ACT were compared. Results have shown that specimens after ACT contains significantly lower content of the Laves phase.
Evaluation of Cavitation Damage in a Pipe Bend Made of 0.5Cr-0.5Mo-0.3V Steel by Optical Metallography and Replica Method
Authors: Kuboň Zdeněk , Kosňovská Jana , Rožnovská Gabriela
Published: November 2020

Prolongation of the service life of key components of fossil-fuelled power plants beyond their original design limit must be accompanied by thorough and extensive monitoring of the actual material state and particularly creep damage. The extent of cavitation is nowadays routinely tested in-situ by using replica method and its quantification is based on practices stated in VGB-TW 507, NORDTEST NT TR 302 derived from the original Neubauer's classification of cavitation damage. Evaluation of cavitation damage based on the measurement of the number of cavities and/or creep micro-cracks has become a routine activity, but in cases when steel contains large amount of non-metallic inclusions, they can be wrongly identified as cavities and to invalidate the result of calculation of cavitation damage. Comparative analysis of cavitation damage was performed in a pipe bend and its weldment made of a low-alloy 0.5Cr-0.5Mo-0.3V steel creep exposed at 540 °C for more than 225,000 hours by using OM (SEM) and replica method and revealed the comparative extent of cavitation damage decreasing from the outer to inner surface of the pipe wall.
Characterisation of Chemical Vapour Deposited AlHfN Coatings
Authors: Rauchenwald Elisabeth , Lessiak Mario , Weissenbacher Ronald , Schwarz Sabine , Haubner Roland
Published: November 2020

Chemical vapour deposited HfN can be utilised as a component of multilayer systems in protective coatings on cutting tools. In this study, related AlHfN coatings were synthesized through a reaction of metallic hafnium and aluminium with HCl gas forming gaseous HfCl4 and AlCl3, which were subsequently transported into a heated coating reactor. Via high temperatures and separately introduced NH3 and N2 as reaction gases, AlHfN coatings were deposited on hardmetal inserts. By varying the ratio between AlCl3 and HfCl4, compositionally different AlHfN coatings were examined. Additionally, surface morphology, composition as well as crystalline phases of the obtained coatings were analysed by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. Finally, the microstructure of the cross section of a coating was investigated via transmission electron microscopy. The observations revealed a great impact of the gas composition on the morphology and crystal structures of the coatings. Within the layer, the growth of columnar microstructures was detected. Additionally, the formation of an amorphous HfN intermediate layer between the substrate and the AlHfN with a thickness of approximately 2 nm was found.
Effects on Microstructure and Corrosion Behavior of a Heat Treated CuZn36Pb2 Brass
Authors: Haubner Roland , Strobl Susanne , Linhardt Paul
Published: November 2020

The brass CuZn36Pb2 is widely used for fittings, valves and other installation materials. Failures are observed occasionally caused by corrosion. Considering the Cu-Zn phase diagram only α-phase exists in the range of 650 and 300 °C. At higher temperatures α- and β-phase is stable and at lower temperatures α- and β´-phase exist. Since the β-phase is Zn-enriches, it is attacked severely by corrosion. In the recent work brass samples were heat treated at temperatures between 850 and 200 °C to study the microstructural changes and the corresponding electrochemical properties. Potentiostatic corrosion tests were applied in artificial fresh water and sea water at different potential settings. After a heat treated at 850 °C the brass has formed b-phase which can be shown by metallography. At lower temperatures the microstructure is fine grained and no β-phase was observed. To verify the presence of β´-phase a heat treatment at 200 °C was performed but no β´-phase was observed, which was confirmed additionally by X-ray diffraction. Again, after corrosion tests the samples were investigated by metallography and the β-phase was obviously more attacked than the α-phase.
Magnesium Alloy WE43 Produced by 3D Printing (SLM)
Authors: Krištofová Patrícia , Roudnická Michaela , Kubásek Jiří , Michalcová Alena , Vojtech Dalibor , Suchý Jan , Paloušek David , Alzubi Enas
Published: November 2020

3D printing is a relatively new and quite attractive form of production, especially for complex parts. In this work, the SLM technology was used to prepare a magnesium alloy WE43 (Mg-4Y-3RE-Zr), a promising material for biodegradable implants. The aim of this study was to map the microstructure and mechanical properties of WE43 produced by SLM and compare it with conventional casting. Microstructure and chemical composition were studied using scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) and transmission electron microscopy (TEM). To examine mechanical properties, hardness measurement, compression tests and three-point flexural tests were carried out.
Characterization of High-Speed Alumina Abrasive Grinding Wheel
Authors: Pavloušková Zina , Jech David , Komarov Pavel , Ročňáková Ivana , Dyčková Lucie , Remešová Michaela , Čelko Ladislav , Holemý Daniel
Published: November 2020

The high-speed grinding wheel can be defined as a self-sharpening composite structural tool composed from abrasive grains held in a specific binder. The main properties of grinding wheels depend on the type of abrasive elements, grit size, grade, binder and the resulting structure, which is influenced by several crucial technological processing steps. Preparation of an initial mixture of abrasive particles together with permanent binder’s mixture and temporary binder followed by pressing and high-temperature sintering is the essential technological step in the manufacturing of high-quality grinding wheels. High demands placed on functionality and quality together with constantly increasing effort to improve existing properties of grinding tools require detailed characterization of all input raw materials. For further research and development is crucial know, how each technological step can influence the final quality of the product. This contribution is focused on the characterization of four alumina abrasives with different grit size and two in chemical composition different binder mixtures which were used for the production of two different high-speed grinding wheels. Initial abrasive grains, binders and metallographic samples of high-speed grinding wheels were evaluated by means of scanning electron microscopy. The porosity of grinding wheels with different binding agents was also determined ustilizing digital image analysis technique.
Step-Sintering of Fe-(1-3)%Mn-0.8%C Steels
Authors: Tenerowicz-Żaba Monika , Sulowski Maciej
Published: November 2020

The aim of the study was to examine how the microstructure changes during heating of Fe-Mn-C system (step-sintering). Mixtures of powders containing 1 – 3 % Mn and 0.8 % C were prepared in Turbula TC2 mixer for 30 minutes. Before step-sintering, the dilatometric investigations were carried out, which allowed to obtain phase transformation temperatures of Fe-(1-3)Mn%-0.8%C system. Following dilatometric investigations, 4 steps – temperatures were determined dependently of isothermal sintering temperature. The commonly used industry temperatures – 1120 °C and 1250 °C – were set as target temperatures. For each of them, 4 heat steps were carried out. The procedure of investigations was as follows: samples were heated to the step temperature with heating rate 60 K/min, then isothermally sintered at step temperature for 5 min, and finally cooled to the room temperature with cooling rate ~ 66 K/min. Fe-Mn-C samples were mechanically (tensile) tested. After tensile tests, metallographic observations of the samples were performed. Based on the results obtained, the tensile strength was increasing with the increasing of the step temperature. The metallographic observation showed the microstructure evolution – with increasing the step temperature, decreasing of porosity was observed.
Characterization of Mg-Zn Layered Bulk Materials Prepared by Powder Metallurgy Method
Authors: Doležal Pavel , Krystýnová Michaela , Marada Tomas , Doležalová Weissmannová Helena
Published: November 2020

In this study three-layered materials composed of one zinc layer between two magnesium layers were prepared. Diffusion at the Mg-Zn boundary leads to the formation of thermodynamically more stable, yet mechanically very brittle intermetallic phase. Homogenous distribution of the fine-grained MgZn2 intermetallic phase in magnesium or zinc alloys has a positive effect on strength of these alloys. In a form of continuous thick layer stretching throughout the whole material, the phase may leads to deterioration of mechanical properties. However, the mechanism of fracture has not yet been sufficiently described. The Mg based materials with one layer of Zn were investigated in terms of chemical composition and mechanical properties and fractographic evaluation. The materials with 0.25 mm, 0.5 mm, 1 mm and 2 mm thick layer of Zn were processed via bidirectional hot pressing method at 300 °C and 500 MPa. The phase and chemical composition of prepared materials was characterized by XRD and SEM-EDS methods. The mechanical properties were evaluated based on the results of three-point bend test and fractographic analysis of fracture surface. The results showed formation of MgZn2 intermetallic phase on the interface of Mg and Zn layers and solid solution of Zn in Mg. The results showed that the presence of Zn layer leads to improvement of mechanical properties when compared to pure Mg prepared at the same condition. The strengthening effect of solid solution and intermetallic phase may be the reason of the increase of flexural strength.
Sintering of High Mn Cemented Carbides in Mn-Rich Environment
Authors: Tarraste Marek , Kübarsepp Jakob , Juhani Kristjan , Kolnes Märt , Viljus Mart , Mere Arvo
Published: November 2020

The economic, environmental and healthcare aspects are pushing cemented carbide industry to reduce or even avoid the usage of conventional binder metals – nickel and cobalt. Commonly, austenitic Fe-Ni alloys have been preferred choice for substituting Co. Similar to Ni, manganese acts as austenite stabilizer and studies have shown that Fe-Mn alloys offer alternative binder metal to Co and Ni in cemented tungsten carbides. In addition, Fe-Mn as a binder potentially offers improved wear resistance due to the well-known wear properties of Fe-Mn-C steels. Addition of chromium to the binder composition increases corrosion performance of composite. Cemented carbides bonded with austenitic FeCrNi binder have demonstrated promising performance. In present work the possibility of achieving austenitic binder phase through substitution of nickel by manganese as an austenite stabilizer is investigated. Structure formation, phase composition and mechanical performance of WC-FeMn and WC-FeCrMn cemented carbides are discussed.
Thermal Cyclic Behaviour of Conventional YSZ and Mullite-YSZ Thermal Barrier Coatings
Authors: Jech David , Komarov Pavel , Remešová Michaela , Dyčková Lucie , Slámečka Karel , Ravaszová Simona , Dvořák Karel , Čelko Ladislav
Published: November 2020

Nowadays commonly used thermal barrier coatings (TBC) are based on yttria stabilized zirconia (YSZ). Addition of mullite phase into the YSZ coating can improve resulting high temperature properties. The contribution focuses on high temperature cyclic oxidation behaviour of two TBC systems with different top coats (TC) deposited by the means of atmospheric plasma spraying. The initial mullite-YSZ powder mixture consisted of 29 vol. % of mullite and 71 vol. % of YSZ. The conventional TBC system consisted of ~ 150 µm thick NiCoCrAlYHfSi bond coat (BC) and ~ 300 µm thick YSZ top coat. The experimental mullite-YSZ (MYSZ) TBC system consisted of ~ 150 µm thick NiCoCrAlYHfSi bond coat, ~ 100 µm thick YSZ interlayer and ~ 200 µm thick mullite-YSZ top coat. The experimental TBC proved higher lifetime, durability and phase stability and also lower grow rate of thermally grown oxide (TGO) compared to conventional TBC. Lifetime, phase stability and changes in the microstructure of TBCs after the furnace cyclic oxidation test were evaluated by the means of scanning electron microscopy equipped with EDX analyzer and X-ray diffraction techniques. Oxidation kinetics of TGO was calculated based on thickness determined utilizing digital image analysis.
Influence of RF Plasma Jet Surface Treatment on Wetting Behavior of Yttria Stabilized Zirconia SPS Coatings
Authors: Komarov Pavel , Jech David , Čelko Ladislav , Pijáková Barbora , Zhou Dapeng , Vaßen Robert
Published: November 2020

According to the value of water contact angle (WCA), the surfaces can be roughly defined as hydrophilic (with WCA less than 90°) or as hydrophobic (with WCA higher than 90°). Water wetting behavior plays important role and surfaces with special wettability (hydrophobic-superhydrophobic; hydrophilic-superhydrophilic) can be used both in the daily life (solar cells, smartphones, car windows, etc.) and in the industry (corrosion resistance, self-cleaning, anti-icing properties, etc.). Nowadays, the development of hydrophobic surface treatment that may be applied in the industry is very interesting topic. Therefore, it was decided to estimate the influence of radiofrequency (RF) plasma jet in atmosphere on wetting behavior of ceramic plasma sprayed coatings. As the initial material for surface treatment, yttria stabilized zirconia suspension plasma sprayed coatings were used. The influence of RF plasma jet on suspension plasma sprayed coatings was estimated on both hydrophilic and hydrophobic surfaces, and resulted water contact angle and free surface energy of modified samples were measured by sessile droplet method. Microstructure, phase composition and topography investigation were carried out by means of light microscopy, X-ray diffraction techniques and non-contact profilometry.
Anodizing of Pure Magnesium in Sodium Hydroxide Electrolyte Solution
Authors: Páleníček Michal , Papula Martin , Remešová Michaela , Jech David , Ročňáková Ivana , Čelko Ladislav
Published: November 2020

Anodizing is an electrochemical process to produced anodic coatings for improving magnesium (Mg) properties such as corrosion-resistant. In this study, anodizing of pure magnesium in 1 M NaOH electrolyte for 1800 s and at 21 °C and different constant current or voltage was investigated. The effect of voltage and current on morphology and thickness of the resulting anodic layers was evaluated by scanning electron microscopy (SEM) equipped with EDX analyser. The thickness of the produced layers was determined to utilize digital image analysis. The results showed that using lower current of 0.08 A non-compact anodic layer was produced. When a higher current of 0.2 and 0.5 A was used compact and thicker anodic layers were produced compare to lower current of 0.08 A. The anodic layer produced at a constant voltage of 20 V was rougher, thicker and contained microcracks compare to anodic layers formed at constant voltage of 12 V and at constant current (0.2 and 0.5 A).
Investigation of the Diffusion Couple Ductile Cast Iron / Iron
Authors: Strobl Susanne , Haubner Roland
Published: November 2020

Forging of ductile cast iron with pure iron by the Damascus technique, results in a new composite material. The combination of cast iron and pure iron is unusual because of its rather different properties. After forging these two materials a small diffusion zone of about 150 µm was observed. Various heat treatments at 900 °C for 2, 4 or 20 hours and 950 °C for 4 h were performed to increase the diffusion zone up to 2.4 mm. At 900 °C carbon solubility in austenite is about 1.2 wt. % and at 950 °C 1.4 wt. %. During the heat treatment carbon diffuses from cast iron into the pure iron and the diffusion gradient grows with time and temperature. Furthermore, the samples were air cooled or water quenched. In the ductile cast iron, graphite nodules are surrounded by ferrite. During the heat treatment graphite is dissolved and pores are observed. In the diffusion gradient layer, a broad range of microstructures observed in hyper- and hypoeutectoid steels could be found. The microstructures were revealed by different etchants and moreover, hardness measurements were performed.
The Microstructure Evolution of Fe-28Al-15Si-0.2Zr Alloy during Different Heat-Treatment
Authors: Švec Martin , Vodičková Věra , Hanus Pavel , Keller Vojtěch
Published: November 2020

The structures of Fe-28Al-15Si-0.2Zr iron aluminide in the as cast state and in three states after heat-treatments (at 800 °C for 100 hours, at 1000 °C for 24 hours and at 1200 °C for 2 hours) were investigated for verification of secondary phases stability. The type and distribution of precipitates were described by means of light optical microscopy and scanning electron microscopy equipped with an energy dispersive analysis. The presence of complex carbides based on Fe-Si-Zr was shown. The bulk hardness and image analysis of samples was measured for verification of dissolution of secondary phase particles to the matrix. Short-term annealing did not influence distribution and dissolution of secondary particles significantly, while long-term annealing (at 800 °C for 100 hours) leads to the sporadic formation of fine eutectic areas.
GEF-H1 Is Required for Colchicine Inhibition of Neutrophil Rolling and Recruitment in Mouse Models of Gout
Authors: Fine Noah , Gracey Eric , Dimitriou Ioannis , La Rose José , Glogauer Michael , Rottapel Robert
Published: November 2020

Gout is a painful arthritic inflammatory disease caused by buildup of monosodium urate (MSU) crystals in the joints. Colchicine, a microtubule-depolymerizing agent that is used in prophylaxis and treatment of acute gout flare, alleviates the painful inflammatory response to MSU crystals. Using i.p. and intra-articular mouse models of gout-like inflammation, we found that GEF-H1/GEF-H1/AHRGEF2, a microtubule-associated Rho-GEF, was necessary for the inhibitory effect of colchicine on neutrophil recruitment. GEF-H1 was required for neutrophil polarization in response to colchicine, characterized by uropod formation, accumulation of F-actin and myosin L chain at the leading edge, and accumulation of phosphorylated myosin L chain, flotillin-2, and P-selectin glycoprotein ligand-1 (PSGL-1) in the uropod. Wild-type neutrophils that were pre-exposed to colchicine failed to roll or accumulate on activated endothelial monolayers, whereas GEF-H1 knockout (GEF-H1−/−) neutrophils were unaffected by treatment with colchicine. In vivo, colchicine blocked MSU-induced recruitment of neutrophils to the peritoneum and the synovium in wild-type mice, but not in GEF-H1−/− mice. Inhibition of macrophage IL-1β production by colchicine was independent of GEF-H1, supporting a neutrophil-intrinsic mode of action. Our results suggest that the anti-inflammatory effects of colchicine in acute gout-like inflammation can be accounted for by inhibition of neutrophil-rolling interactions with the inflamed vasculature and occurs through GEF-H1–dependent neutrophil stimulation by colchicine. These results contribute to our understanding of the therapeutic action of colchicine, and could inform the application of this drug in other conditions.
Differences in Leaf Area, Trichome Density, and Xylem Structure between the Two Types of Theobroma cacao L. Cultivation: With or without Shade Plants
Authors: Prihastanti Erma , Nurchayati Yulita
Published: November 2020

This study aimed to analyze the structure and density of non-glandular trichomes and the area of cocoa leaves, and the differences of xylem vessel structures on various shade tree composition. The leaf area and length, and trichomes were observed. The xylem vessel structure was observed from the root system. The result showed the area of cocoa plots without shade tree has more varied leaves size, in which upper canopy was smaller than the bottom. The area with various shade had a relatively equal size between the upper and the lower of the canopy. The three stellate-shaped non-glandular trichomes were found on the leaf venations only with the density in two plots increased with time. The xylem width area to the whole root width area ratio (k) in various shade trees was lower (k = 0.641) than that of without shade trees (k = 0.718). The higher k values indicated xylem structure without the shade tree had more xylem cells, and the pores was smaller compared to the plot with various shade trees.
Determining the Dose of Dietary Probiotic (Bacillus licheniformis) for the Nursing of Blue Swimming Crablets (Portunus pelagicus, L., 1758)
Authors: Boonyapakdee Anawat , Bhujel Ram
Published: November 2020

Various efforts have been made to use probiotics instead of antibiotics in aquaculture to solve the problem of low survival and slow growth of hatchlings. Selection of probiotics strain and their right dose have been the major challenges. Limited research has been done in blue swimming crab (Portunus pelagicus L., 1758). Therefore, present study was carried out to determine the effects of varying doses of probiotic Bacillus licheniformis 107 colony forming unit (CFU)/mL i.e. 0.0, 1.5, 3.0, and 6.0 mL/kg on the survival, growth and moulting of blue swimming crablets nursed for 45 days and determine the right dose. The four treatments were replicated thrice in 500 L plastic tanks. Regression analysis revealed that the probiotic dose had significant (P<0.05) positive relationships with carapace length gain, weight gain, and moulting percentage; but negative relationship with food conversion ratio. Vibrio colony growth was significantly (P<0.05) inhibited at the dose of 3.3 mL/kg feed or higher. Results showed that increased doses of Bacillus licheniformis enhanced the growth and moulting of blue swimming crablets. The highest moulting percentage of 89 % was found at an extrapolated dose of 6.9 mL/kg feed.
Growth Performance, Chemical Composition of Fillets, Liver and Intestinal Histology, and Expression of Lipid-Dependent Genes in Common Carp (Cyprinus carpio) Fed Artificial Diets
Authors: Eljasik Piotr , Panicz Remigiusz , Sobczak Małgorzata , Sadowski Jacek , Ostaszewska Teresa
Published: November 2020

The study is a preface to redesign farming of carp, and the aim was to determine the influence of three artificial feeds on carp growth performance, chemical composition, intestinal and liver histology, and the expression of two main genes of fatty acid catabolism: acyl-coenzyme A oxidase 1 (acox1) and peroxisome proliferator-activated receptor  (ppar). The 61-days trials were run in set of 9 floating cages in triplicate (n=3 per diet). The results showed that zootechnical parameters (i.e. feed conversion ratio, protein efficiency ratio) significantly improved with increased level of fat in diet, for instance, the lowest FCR was noted for fish fed diet A (9.900.23% of fat). Additionally, gene expression analysis revealed that activity of acox1 and ppar in the liver depend on the fat level in carp diet. The expression of ppar and its target gene acox1 in the intestine of fish showed a distinct pattern in relation to liver samples, since feeds with high and low levels of fat exerted a comparable effect on the mRNA level of the studied genes. In conclusion, this study showed that the level of fat in common carp diets correlated with the level of lipids in the meat.
Недавние результаты в многомерном комплексном анализе и комплексной геометрии
Authors: Zhou Xiang Yu
Published: November 2020

Приводятся основные предварительные сведения и формулировки задачи об оптимальном $L^2$‑продолжении, гипотезы Демайи о сильной открытости для пучков мультипликаторных идеалов и некоторых близких задач, а также описаны недавние решения этих задач, полученные автором и его учениками. Также дается обзор некоторых новых результатов по смежным вопросам многомерного комплексного анализа и комплексной геометрии.
Ovarian follicular dynamics in Boran and Crossbred heifers in Ethiopia: Implications for assisted reproductive techniques
Authors: Jemal Jeilu , Degefa Tamrat , Yilma Tefera , Ali Sayid , Alemayehu Lemma
Published: November 2020

The study was conducted to characterize the follicular dynamics of purebred Boran (Bos indicus) and Boran * Holstein Friesian crossbred heifers  during estrous cycles; for use in ovum pick up and in-vitro embryo production. Insight of reproductive physiology of cattle would help to understand and exploit the reproductive potential of elite animals for breed improvement. Follicular development, growth and atresia during estrous cycles were evaluated using a trans-rectal real-time B-mode ultrasound system for three consecutive estrus cycles. Luteal activity was evaluated by serum progesterone level. Follicular aspirations were done to investigate the potential of Boran cattle and their crosses for transvaginal oocyte production; using a vacuum pressure pump and Aloka SSD Prosound-2 ultrasound device. Boran heifers (n=15) manifested two (n = 6, 40%), three (n = 5, 33%), four (n= 3, 20%) and five (n=1, 6.7%) follicular waves. Crossbred heifers (n=14) showed one (n= 2, 14%), two (n= 6, 43%) and three (n= 6, 43%) follicular waves. Interovulatory interval was 21.1 ± 3.4 and 21.4 ± 2.7 days for Boran (n=45) and crossbred (n=42) heifers, respectively. The progesterone level in Boran and Crossbred heifers during diestrus was 9.5 ± 11.0 and 4.6 ± 8.8 ng/ml, respectively. The maximum diameter of the ovulatory follicle for crossbred heifers was higher (15.4 ± 1.6 mm) than the diameter of the Boran (14.0 ± 1.9 mm) heifers (p<0.005). Differences (p<0.005) were observed in the size of both right (26.6 ± 5.14 and 28.6 ± 5.1 mm) and left (21.7 ± 4.85 and 24.1 ± 5.07 mm) ovaries of Boran and Crossbred heifers, respectively. Difference (p<0.005) was also observed in follicular count of the  right ovaries of Boran (4.84 ± 1.96) and Crossbred  (5.13 ± 2.05) heifers. Oocyte recovery rate in once weekly collection scheme for Boran and their crossbred heifers was (n=19, 42.08%) and (n=17, 42.55%), respectively. The recovery rate for twice weekly collection scheme was (n=24, 34.53%) and (n=23, 40.44%) for Boran and crossbred heifers, respectively. Follicular dynamics in Boran heifers is characterized by a higher incidence of cycles with two, three and four waves, associated with a low persistence of the dominant follicles; and smaller size of ovulatory follicles and less intense heat signs from their crossbred counterpart. Boran heifers proved to have potential for comparable number of follicular population and ease of aspiration procedures that can be tapped for advancedreproductive techniques.

Keywords: Estrus cycle; follicular wave; ovarian follicle; ovum pickup; ultrasound.