bluuebunny/crossref_metadata_2025 huggingface dataset:
Pervaporation Separation of Toluene/TEG Mixture with PIM-1 Membrane
Authors: Podtynnikov Ivan A. , Balynin Alexey V. , Yushkin Alexey A. , Budd Peter M. , Volkov Alexey V. , Borisov Ilya L.
Published: October 2020

Dense membranes made of polybenzodioxane (PIM-1) were developed for pervaporation of toluene/TEG mixtures. The effect of experiment time on membrane characteristics such as flux and separation factor was investigated. The neat PIM-1 membranes showed high toluene flux of 2.45 kg/m2∙h, but low separation factor of 4. The cross-linking of PIM-1 using AlCl3 leads to an increase in the separation factor up to 20, with some compromise of toluene flux down to 0.76 kg/m2∙h.
Properties of Polysulfone Hollow Fiber Membranes Depending on the Method of the Spinning Solution Preparing
Authors: Matveev Dmitry N. , Vasilevsky Vladimir P. , Kutuzov Kirill A.
Published: October 2020

The spinning solution properties (viscosity, chemical composition) can be varied depending on the method of its preparation. These variations might cause changes in the thermodynamics and kinetics of the phase separation process during the membrane formation. In this work, the influence of various modes of spinning solution preparation on the morphology, geometric and gas transport properties of the resulting polysulfone (PSf) hollow fiber membranes was investigated. The differences in methods of solution preparation were the temperature and time of stirring. It was found that with the transition to the lower-temperature stirring of the spinning solution the outer diameter and wall thickness of the fiber increase, and the thickness of the selective layer decreases. The highest ideal selectivity values are observed with the solution stirring for 5 hours at temperature 120 °С (3.1 for pair He/CO2). The maximum values of the gas permeability are achieved in the mode of the solution stirring for 24 hours at temperature 50 °C (P/l (He) = 201 m3/( m2∙h∙atm); P/l (CO2) = 83 m3/( m2∙h∙atm)).
Gas Separation Membranes Based on Germanium Containing Polyalkylenesiloxane
Authors: Borisov Ilya L. , Ushakov Nikolay , Grushevenko Evgenia , Finkel’stein Evgeny , Volkov Vladimir
Published: October 2020

An original method for the synthesis of monomer for the preparation of a new membrane polymer, 2,2,4,4,6,6-hexamethyl-1-oxa-2,6-disyl-4-germanocyclohexane, is proposed, which allows increasing the yield of the target substance. By polycondensation polymerization, a membrane-forming germanium-containing polycarbosiloxane was synthesized. Based on it, new highly permeable membranes with high selectivity of butane / methane were first obtained and studied. When comparing the transport properties of silicon and germanium-containing polymers, it was found that polycarbosiloxane containing germanium atoms in the main chain shows higher values of butane selectivity and permeability.
Synthesis of Aromatic Polyether Ketones by Electrophilic Substitution
Authors: Shakhmurzova Kamila T. , Kurdanova Zhanna I. , Zhansitov Azamat A. , Balagova Marina , Khashirova Svetlana Yu.
Published: October 2020

This article presents a scientific review of the literature on the production of polyether ketones and copolymers of various structures with a complex of valuable properties. Particular attention is paid to the synthesis of polyether ketones by electrophilic substitution by the Friedel-Crafts reaction mechanism.
Investigation of the Effect of the Length and Content of Carbon Fibers on the Properties of Polyphenylene Sulfide
Authors: Slonov Azamat L. , Musov Ismel V. , Rzhevskaya Elena V. , Zhansitov Azamat A. , Khashirova Svetlana
Published: October 2020

The article presents the results of a study of the effect of milled and chopped carbon fibers, with an average particle length of 0.2 and , respectively, on the mechanical properties of polyphenylene sulfide and its heat resistance. It was found that the introduction of carbon fibers leads to a significant decrease in the melt flow rate. It was shown that after a sharp decrease in impact strength at 10 % content of carbon fibers, its inverse improvement occurs with an increase in the filler content. Composites containing carbon fibers with length demonstrate higher impact strength. The introduction of a filler leads to a significant increase in the elastic modulus and strength of polyphenylene sulfide and its heat resistance.
The Effect of Sizing Additives for Carbon Fiber on the Mechanical Properties of Polyetherimide Composites
Authors: Beev Aues A. , Khashirova Svetlana , Slonov Azamat L. , Musov Ismel V. , Zhansitov Azamat A. , Beeva Dzhul’etta A.
Published: October 2020

The article presents the results of sizing of discrete carbon fibers with various substances and their effect on the properties of polyetherimide composites. As sizing agents, 1,3-diaminobenzene, 4,4'-dihydroxy-2,2-diphenylpropane, polyetherimide and oligoetherether sulfone were used. The study of physical and mechanical properties showed that all the substances used increase the properties of the carbon-filled composite based on polyetherimide. The highest mechanical properties are demonstrated by a composite containing carbon fibers treated with 1,3-diaminobenzene, which indicates improved compatibility of the filler and the polymer matrix and enhanced intermolecular interactions.
Biologically Destroyable Polymer Compositions with the Use of Natural Filler
Authors: Vindizheva Amina , Khashirova Svetlana Yu. , Kalabin Alexandr
Published: October 2020

We presented a scientific review of the literature on known biodegradable polymer composite materials and summarized the data on the effect of starch and thermoplastic starch on the biodegradability of industrially produced polymers. We considered the main starch plasticizers.
Influence of Casting Method on Pervaporational Performanses of Polyheptylmethylsiloxane Membranes
Authors: Grushevenko Evgenia , Podtynnikov Ivan A. , Sharova Olga , Anokhina Tatyana S. , Borisov Ilya L.
Published: October 2020

A method of composite membrane obtaining effects on its transport properties. In the present work, for the first time, the influence of the method of applying a selective layer of polyheptylmethylsiloxane on the composite membrane pervaporation properties in the process of alcohol separation from water was studied. The comparison of two casting methods (kiss-coating and spin-coating) was conducted. Morphology of the obtained membranes and their separation properties during the pervaporation of the mixture of C2-C4 alcohols and water. It was shown that kiss-coating allows completely prevent leakage of the selective layer into the substrate pores. And, such a way, it allows to improve permeability of composite membrane (BuOH - 3.5 mol/(kPa·h·m2)). Besides, spin-coating method leads to higher selectivity (BuOH/H2O - 2.3). It is caused by blocking the swelling of that part of the selective layer that is locked in the pores of the substrate. Thus, the choice of the casting method can determine the compatibility of the composite membrane with a specific separation task.
On the Synthesis of Copolyarylene Ether Ketones by Nucleophilic Substitution Reaction
Authors: Beev Aues A. , Khashirova Svetlana , Beeva Dzhul’etta A. , Shokumova Milana U.
Published: October 2020

The dependence of the reduced viscosity of copolyarylene ether ketones on the chemical structure of diols and the conditions for copolycondensation is studied. It was shown that the structure of diols and the order of their introduction into the polycondensation reaction affect the reduced viscosity, impact strength, and temperature characteristics of copolyarylene ether ketones.
The Effect of Water on the Thermal and Thermooxidative Destruction Processes of some Polyheteroarylenes
Authors: Shabaev Albert S. , Khashirova Svetlana , Kalabin Alexandr
Published: October 2020

The temperature-time modules of drying and heat treatment of polyetherketones and polyphenylene sulfides are revealed; which made it completely possible to get rid of sorption water and an upper limit noticeable worsens the thermal stability of polymers. The most vulnerable bonds in polysulfones to the effects of water at processing temperatures were found.
Investigation of the Ability of the Organophosphorus Compound Tetrakis(2,4-Di-Tert-Butylphenyl)-4,4'-Biphenyl Diphosphonite to Polyetheretherketone Stabilize
Authors: Shabaev Albert S. , Khakyasheva Elina V. , Shetov Ruslan A. , Khashirova Svetlana
Published: October 2020

The method of gas chromatography was used to study of the stabilizing effect of the organophosphorus compound tetrakis (2,4-di-tert-butylphenyl)-4,4-biphenyl diphosphonite on polyether ether ketone. The possibility of maintaining the structure of polyetheretherketone under conditions of its extrusion processing without the risk of deterioration of the main technological and operational characteristics is revealed.
The Influence of Sparse Filling of FDM-Printed Samples on Mechanical Properties of Polyphenylene Sulfone and a Carbon-Filled Composite Based on it
Authors: Khashirov Azamat A. , Slonov Azamat L. , Musov Ismel V.
Published: October 2020

FDM-printing technology is widely used in many fields including highly responsible industries such as aerospace, oil and gas and automotive manufacturing. Polyphenylene sulfone and its composites are one of the most common used high-performance polymers in those fields but polyphenylene sulfone is expensive and the lower material would be used for production the more applications could be able to enroot polyphenylene sulfone to their industries. Additive manufacturing opens new boundaries comparing to traditional technologies allowing to use the grid filling of parts which can help to reduce the material expenditure. In this research the influence of grid filling to mechanical properties of polyphenylene sulfone and its carbon-filled composite samples obtained using FDM-printing technology was studied. The article includes results about the effect of various grid sizes and its type on the mechanical properties of polyphenylene sulfone and its carbon-filled composite samples, and It shows the possibility of significant material savings while maintaining the required product properties.
Modification of Industrial Polyphenylene Ether Sulfone by New Block Copolymers Containing Oxime Groups
Authors: Musaev Yurii I. , Musaeva Eleonora B. , Baykaziev Artur E. , Khashirov Azamat A. , Danilova-Volkovskaya Galina M.
Published: October 2020

New universal modifiers (UM) - simple block copoly-ether-hydroximates of various chemical structures were synthesized. It was found that a 5 % by weight addition of UM to Radel R, an industrial aromatic simple polyethersulfone, improves its heat, heat resistance and physicomechanical properties.
Composite Materials Based on Natural Polysaccharides and Polyguanidines
Authors: Khashirova Seda S. , Isupova Zalina Yu. , Khashirova Svetlana , Khasanov Vladislav V.
Published: October 2020

Composite materials based on natural polysaccharides and polyguanidines are considered. The synthesis mechanisms and structural features of composite materials based on polyguanidines and polysaccharides are discussed. The issues of the relationship of their structure with antimicrobial activity are highlighted. It has been shown that the modification of polysaccharides with guanidine-containing compounds makes it possible to give them bactericidal properties, increase strength and solubility, and is a promising direction for the development of new-generation drugs.
Infrared Spectrum and Thermal Properties of LDPE, EVA and Fly Ash Composites
Authors: Trong Vu Minh , Hoan Bui Dinh
Published: October 2020

The polymer composites based on low-density polyethylene (LDPE), ethylene vinyl acetate copolymer (EVA) and fly ash (FA) without and with vinyltrimetoxysilan (VTMS) modification were prepared by melt mixing in a Haake Rheomixer. The FT-IR spectra indicated the bonds between LDPE/EVA and FA modified by vinyltrimetoxysilan were dipole - dipole interaction and hydrogen bonding. Thermal oxidation stability of the LDPE/EVA/VFA composites are higher than those of the LDPE/EVA/FA composites. Thermal oxidation stability of the LDPE/EVA/VFA composites and the LDPE/EVA/FA composites were higher than the LDPE/EVA blends. Putting fly ash into polymers, thermal oxidation stability of composites increased and significantly increased when using modified fly ash (MFA).
Thermoplastic Characteristics of Polymer Composite Materials Used for the Manufacture of Ship Systems Pipelines
Authors: Ngo Gia Viet
Published: October 2020

The article presents thermoplastic characteristics of polymer composite materials developed on domestic raw materials on a thermoplastic matrix-injection material of the VTP-7 brand based on polyaryl sulfones (polysulfone PSU) plastic and sheet material of the VKU-44 brand based on PSU and carbon unidirectional tape ELUR 0.08 PA. In the article, the author considered the modification method of thermoplastic polymers to impart functional properties and mechanisms of their action. It is shown that the developed materials have no analogues in the domestic industry. According to the level of physical and mechanical characteristics, fire-hazard properties and heat resistance, the developed polymer composite materials (PCM) fully meets the requirements for modern thermoplastic PCM, and is not inferior to foreign analogues.
Morphology and Mechanical Properties of LDPE, EVA and Fly Ash Composites
Authors: Trong Vu Minh , Hoan Bui Dinh
Published: October 2020

The fly ash from Pha Lai power plant was modified by vinyltrimetoxysilan (VTMS). The polymer composites based on low-density polyethylene (LDPE), ethylene vinyl acetate copolymer (EVA) and fly ash (FA) without and with vinyltrimetoxysilan (VTMS) modification were prepared by melt mixing in a Haake Rheomixer. The tensile strength and elongation at break of the LDPE/EVA/VFA composites were also higher than those of the LDPE/EVA/FA composites. The FESEM images proved that FA-VTMS particles disperse more regularly in the polymer matrix in comparison with FA without VTMS modification. In addition, the surface modification of the FA reduced the size of agglomeration of FA particles.
Application of Adhesives in Cosmetology
Authors: Galimzyanova Rezeda Yu. , Garifullina Aisylu R. , Garipov Radif R. , Lisanevich Maria S. , Musin Ildar N.
Published: October 2020

The current state of the cosmetology industry in the field of eyelash extension services is analyzed. It is concluded that the popularity of this type of service, despite the negative impact on eye health, will grow in the near future. The main symptoms that occur when using this procedure are analyzed. Among the most common symptoms should be noted a feeling of heaviness of the eyelids, burning, discomfort associated with a decrease in the field of view. It is noted that despite a number of works in this area to date, there is insufficient research, both from the point of view of the analysis of clinical cases, and from the point of view of developing safer adhesive compositions. An analysis is made of the characteristics of adhesives used in domestic cosmetology rooms. At the same time, attention was paid to the following: country of production, composition, texture and texture, setting speed, wearing time, shelf life, recommended temperature and humidity level. A typical composition of glue for eyelash extension contains the following components: cyanoacrylate and its derivatives (± 90 %); polymethylmethacrylate (PMMA) (± 6 %); black pigment - carbon black (± 4 %).
Tensile Properties of Epoxy Matrix Reinforced with Fique Fabric
Authors: Oliveira Michelle Souza , Filho Fabio da Costa Garcia , da Luz Fernanda Santos , Pereira Artur Camposo , Demosthenes Luana Cristyne da Cruz , Nascimento Lucio Fabio Cassiano , Monteiro Sergio Neves
Published: October 2020

Composite materials are being extensively studied for ballistic armor. Their main advantage is connected to the possibility of deeply reducing weight and costs by maintaining high performances in terms of strength and security. Epoxy composites are reinforced with natural fibers which are replacing other synthetic reinforcement materials. Composites are prepared using polymers as matrix material because of ease of production with different reinforcements. The mechanical strength of the natural fiber reinforced polymer composites has been compared with synthetic fiber reinforced polymer composites and it is found that for achieving equivalent mechanical strength of the material, the volume fraction of the natural fiber should be much higher than synthetic fiber. This work being an experimental study on untreated “as received” fique fabric-reinforced epoxy composites, to demonstrate the potential of this renewable source of natural fiber for use in a number of applications.
Influence of the Electrolyte Potential Window on the Electrical Characteristics of Supercapacitors Operating Elevated Temperatures
Authors: Silva L.S.V. , Mansani G.L. , Yoshikawa D.S. , Casini J.C.S. , Faria R.N.
Published: October 2020

The equivalent series resistances (ESR) and specific capacitances (Cs) of supercapacitors carbon electrodes have been investigated using cyclic voltammetry and electrochemical impedance spectroscopy. Commercial activated carbon electrodes employing organic electrolyte have been tested using a potential window in the range of 2.7–3.8 V. Specific capacitances were calculated from cyclic voltammetry curves at room temperature employing various scan rates (30 and 100mVs-1). Internal series resistances of the supercapacitors were measured using the galvanostatic curves at room temperature and above (25 and 50°C). The ESR increase to 9.8 Ω at 25° and 2.7V to 78.8 Ω at with operating temperature raise and also with overpotential. A compositional and morphological evaluation of these electrodes showed a very homogeneous structure. It has been shown that the specific capacitance decreased considerably with scan rate, current density, electrochemical potential window and working temperature.
Thickness Estimation of TiO2-Based Nanotubes Using X-Ray Diffraction Techniques
Authors: Faria Marcela E.M. , Leite Marina M. , Ichikawa Rodrigo U. , Vichi Flávio M. , Turrillas X. , Martinez Luís Gallego
Published: October 2020

TiO2-based nanotubes are a very promising material with many applications in solar cells, biomedical devices, gas sensors, hydrogen generation, supercapacitors, and lithium batteries, among others. Nanotube thickness is a very important property since it is related to electronic and surface mechanics. In this sense, transmission electron microscopy (TEM) can be used. However, it can be difficult to acquire a good TEM image because the transversal section of the nanotubes needs to be visible. In this work, TiO2-based nanotubes obtained via hydrothermal synthesis were studied using X-ray line profile analysis. Scherrer and Single-Line methods provided consistent results for the thickness of the nanotubes (≃ 5 nm) when compared with TEM. Additionally, Single-Line method was also applied to estimate the microstrain. The advantage of using XRD is given by the fact that it is a quick and statistically significant analysis when compared with TEM. The results show that XRD can be used as a rapid and reliable alternative for the thickness estimation of nanotubes.
Sintering Behavior of AL2O3 Ceramics Doped with Pre-Sintered NB2O5 and LiF
Authors: da Silveira Pedro Henrique Poubel Mendonça , de Jesus Paulo Roberto Rodrigues , Ribeiro Matheus Pereira , Monteiro Sergio Neves , De Oliveira Julio César Soares , Gomes Alaelson Vieira
Published: October 2020

A study was carried out on the behavior during the sintering of Al2O3 ceramics with pre-sintering of the additives Nb2O5 and LiF at different temperatures. It was observed through XRD and DSC the formation of the LiNb3O8, Nb3O7F and LiNbO3 phases during the pre-sintering of the additive powders and the formation of the LiAl5O8, AlNbO4 phases during the sintering of the samples The samples showed densities around 91% of the theoretical density, and pre-sintered samples showed low growth in grain size.
Comparison of Mechanical Properties of Banana Fibers Reinforcement in Different Thermoset Matrix Composites
Authors: Filho Fabio da Costa Garcia , Oliveira Michelle Souza , de Assis Foluke Salgado , Pereira Artur Camposo , da Luz Fernanda Santos , Demosthenes Luana Cristyne da Cruz , Monteiro Sergio Neves
Published: October 2020

Banana fibers are among the natural lignocellulosic fibers with greater potential for use as reinforcement in polymer matrix composites. Attractive mechanical and physical properties as well as low cost of production are considered as the main advantages on the use of such fibers. This works aims to study the mechanical behavior of the banana fiber when used as filler to the two most commonly used thermoset matrices (epoxy and polyester). The specimens were produced with up to 30 vol% of banana fibers for both polymeric matrices. Tensile strength tests as well as macroscopic and microscopic evaluation of the fractured surface were carried out. It was shown that, indeed, the banana fiber provided a substantial reinforcement for both matrices. On the other hand, mechanical strength associated with the composite epoxy/banana was more than 50% higher than the exhibit by the polyester/banana one. Such behavior could be associated with the interfacial strength regarding the fiber and the matrix.
Use of Ceramic Waste for the Manufacture of Sintered Parts
Authors: de Souza Vanessa Moura , Martins Vinícius , Tubino Rejane Maria Candiota
Published: October 2020

This paper evaluated the use of the pitcher, a ceramic waste obtained through the quality process of a sanitary ware industry, in the development of a material for usage in the manufacture of sintered parts. The pitcher was obtained through powder technology and is composed, according to the chemical analysis obtained by X-ray fluorescence spectrometry, of clayey minerals (clay and kaolin), quartz, and feldspar, which may include ceramic rocks such as granite, pegmatite and phyllite; that is, it has proved to be a potential raw material due to the minerals that can still be reused. The pitcher passed through a granulometry-based selection process, sieving about 20kg using the following sieve sequence: 18 MESH, 25 MESH, 30 MESH, 120 MESH and 400 MESH; with around 70% of the residue being retained in the sieves of 120 and 400 MESH, which were selected to be used in the evaluation. The samples were compacted in a manual press with different pressures, between 300 and 1000 kgf, and after were sintered at a temperature of 1100oC in a resistive furnace. To characterize the material, the apparent and green density, as well as the compressibility curve, were determined to identify the best compression pressure. The microstructure of the test specimen and the pitcher homogeneity were evaluated using Scanning Electron Microscopy (SEM). Both particle sizes presented the typical compressibility curve, in which the density increases with increasing compaction pressure, while the curve slope decreases with increasing pressure. The density increase with the increasing compaction pressure indicates a good densification for the temperatures, independent of the sample granulometry. The sintering porosity decreased proportionally to the particle size in the sintered samples. The analysis showed that the particle size of 400 MESH sintered at 1100oC obtained more porous surfaces, thus indicating a promising future for the manufacture of parts using powder technology, especially for the development of filters.
Microstructural Characterization of Slag Residue Incorporated into Clay for Production of Red Ceramics
Authors: Silva Clara Giovana Souza , de Jesus Geyna Evellyn Silva , dos Santos Jheison Lopes , Monteiro Sergio Neves , de Souza Costa Roberta Lima , Rios da Silva Alisson Clay , Candido Verônica Scarpini
Published: October 2020

This study aims to characterize slag and from a steel mill and clays from in the state of Pará, aiming at its incorporation into clays for tiles production. The waste passed through the processing step X-ray diffraction (XRD) and X-ray fluorescence (XRF) were performed. Besides that, strong and weak clays from state of Pará were also analyzed by thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and XRD. The results showed that hematite, magnetite and wustite are the predominant phases. The chemical analysis by XRF showed that the residue presents low levels of silica (SiO2) and alumina (Al2O3) associated with elevated levels of iron oxide. Thus, the characterization of steel slag showed that this residue presents itself as a potential ceramic constituent and can contribute to the formation of liquid phase during which it would lead to improvement of technological properties such as water absorption and mechanical resistance.
Effect of Post-Weld Heat Treatment on Hardness in Superduplex Stainless Steel ASTM A890/A890M - Grade 6A
Authors: de Oliveira Clélia Ribeiro , Lopes Maia Eloá , da Fonseca Solange T. , Martins Marcelo , Ávila Díaz Julián Arnaldo , Mei Paulo Roberto
Published: October 2020

Superduplex stainless steel alloy exhibit high mechanical and corrosion resistance, which main industrial application is in the petrochemical industry. The manufacture and maintenance of such equipment usually involve welding processes, followed by post-welded heat treatment and it often becomes impossible to apply heat treatments. Thereby, the purpose of this work is to verify the effect of a post-welded heat treatment on shielded metal arc welding in steel grade ASTM A890/A890M - grade 6A. The microstructure in the as-welded condition consisted of austenite, secondary austenite, and ferrite phases and, the post-welded heat treatment condition exhibited only austenite and ferrite. The hardness in the melt zone reached values of 300 HV after welding and, the value was reduced to 260 HV in the post-welded heat treatment condition.
PrFeB Based Alloys Obtained by Melt Spinning for the Production of Permanent Magnets
Authors: Meira Marco Antonio , Moisés Lucas Costa , da Silva Melissa Rohrig Martins , Real Janasi Susilene , Takiishi Hidetoshi
Published: October 2020

Rare earth permanent magnets are essential components in many fields of technology due to their excellent magnetic properties. There are some techniques used in the manufacture of permanent rare earth magnets: the powder metallurgy to obtain anisotropic HD sintered permanent magnets and the melt spinning and HDDR processes to obtain isotropic and anisotropic bonded permanent magnets. In this work, the influence of the melt spinning parameters on the microstructural and magnetic properties of the Pr14FebalCo16B6 alloy was studied. The alloy was melted and rapidly cooled at 9.9 x 105°C/s. The parameters used in the process were: wheel speed of 15 m/s and 20 m/s and ejection pressure of 25.3 kPa and 50.7 kPa. Ribbons and/or flakes of 30 μm thickness and width until 5 mm were obtained. Results show that the melt spinning alloys are nanocrystalline and that the parameters of the process influence the microstructure and their magnetic properties. Mean crystallite size up to 38.5 nm and intrinsic coercivity (iHc) up to 254 kA/m were obtained.
Thermal Transformations of the Nickel Laterite Agglomerate Phases and their Metallurgical Influence
Authors: da Silveira Rosinaldo Fonseca , Fernandez Oscar Jesus Choque , da Luz Patrícia Tereza Souza , da Costa Jaime Henrique Barbosa
Published: October 2020

In nickel laterite agglomerates from rotary kiln of RKEF process the phases lizardite and/or chrysotile, clinochlore, quartz and hematite were identified. The product contain SiO2 (32.67%), Fe2O3 (24.68%), MgO (21.81%) and NiO (3.30%) as principal components. When thermal treatment were carried out weight differences can be observed where the adsorbed water removed during drying, without phase changes in temperatures ranging from 60°C to 100°C, indicated influence of mineral assemblage. Phase changes and weight loss was observed in calcination with clear crystalline restructuring of the serpentines and clinochlore at 500°C. Above this temperature new phases are crystallized until 820°C, when is formed forsterite and enstatite, provably trevorite and remaining unchanged quartz. There were identified nickel minerals. The nickel occurs in bearing phases as Mg-Ni ion substitution in the crystal structure. On the analyzed conditions might infer that these new phases formed can affect the pyrometallurgical process of reduction.
Characterization and Evaluation of Mechanical Properties and Residual Stress in Aluminum-Magnesium Alloys Welded by the FSW Process
Authors: Colaço D.B. , Ribeiro M.A. , Maciel T.M. , de Melo R.H.F.
Published: October 2020

The demand for lighter materials with suitable mechanical properties and a high resistance to corrosion has been increasing in the industries. Therefore, aluminum appears as an alternative due to its set of properties. The aim of this work was to evaluate residual stress levels and mechanical properties of welded joints of Aluminum-Magnesium alloy AA 5083-O using the Friction Stir Welding process. For mechanical characterization were performed a uniaxial tensile test, Vickers hardness, bending test and, finally, the determination of residual stresses. It was concluded that welding by FSW process with an angle of inclination of the tool at 3o, established better results due to better mixing of materials. The best results of tensile strength and a lower level of residual stresses were obtained using a tool rotation speed of 340 RPM with welding advance speed of 180 mm/min and 70 mm/min.
Influence of Mercerization Process on the Surface of Coconut Fiber for Composite Reinforcement
Authors: da Silva Nicolau Géssica , Weber Ricardo Pondé , Monteiro Sergio Neves , Loureiro Gabriela Azevedo , Lavinsky Amanda Assis , da Fonseca Letícia Vieira , da Silva Eduardo Gonçalves , dos Santos Pedro Luiz Barrozo , Abranches Rodrigo Pereira , Machado Vinícius Cordeiro
Published: October 2020

The high consumption of green coconut water, especially in tropical countries like Brazil, generates an aggravating factor to the environment, which is associated with the waste generated after its consumption. Thus, one of the possible ways of reusing the coconut shell after consumption is through the extraction of its fibers, which are considered for several applications. In general, natural lignocellulosic fibers (NLFs) have been used for many purposes, such as reinforcement filler in composite materials, since they have low cost and good mechanical properties. With the intention of providing a better compatibility between the NLFs and the composite polymeric matrix, different types of surface treatments are carried out on the fibers, including mercerization, a chemical treatment in which a basic solution is used. In this sense, the present work aims to verify the influence of mercerization with 3% sodium hydroxide (NaOH) on coconut fiber. Among the analyses carried out, stands the scanning electron microscope (SEM) on fresh and treated coconut fibers. The SEM analyses, allowed to observe that after treatment via mercerization, the fibers displayed a greater surface roughness. This indicates the partial removal of lignin, hemicellulose and some other extracts present on the outer layer of the coconut fiber. Therefore, mercerization will probably enable a better mechanical anchoring between fiber and matrix. Results obtained suggest the effectiveness of the mercerization process. However, it was also of concern that such treatment tends to generate NaOH residues, which is a negative factor regarding sustainability.
Study of Superioring of a Seal Soldered by Tig Process of the Aluminum League 6061
Authors: da Silva J.A. , Miranda A.G. , Kimura S.P.R. , Freitas B.M. , Silva R.N.A. , Costa J.C.M. , Neto J.C. de Macêdo , Guimarães Leite S.C.
Published: October 2020

The aim of this work was to verify the mechanical behavior of a Gas Inert Tungsten (TIG) welded joint of a 6061 aluminum alloy, after aging and super-aging thermal treatments. The characteristics of aluminum allow diversified applications, which contributes as one of the most used metals in the world. Being a lightweight, durable and sturdy material, it shows excellent performance and superior properties in most applications. Brazil is the eleventh primary aluminum producer, preceded by China, Russia, Canada, the United Arab Emirates, India, Australia, the United States, Norway, Bahrain and Saudi Arabia. The specific objectives were to obtain welded joints in aluminum by TIG process, performing the thermal treatments of aging and super-aging, metallography/macrography tests of welded joints, microhardness test of treated and untreated joints, and analysis of the results. The methodology used in the analysis of the samples was by the techniques of Metalografia and Microhardness.
Failure Analysis of Metallic Orthopedic Implant for Total Knee Replacement
Authors: Pieretti Eurico F. , Leivas Tomaz P. , Pillis Marina F. , das Neves Mauricio David Martins
Published: October 2020

Fractures resulting from wear and fatigue process have been identified as the main causes of failure in biomaterials, especially in implants that act in place of bone or other hard tissue, as they are subject to conditions involving severe cyclic loadings. In biomaterialscase, the types of failures mentioned above must also be evaluated under the effect of degradation or corrosion, due to the direct contact with body fluids. The present research analyzed the fatigue induced by corrosion fracture of an orthopaedic implant for total knee replacementproduced with an austenitic ASTM F138 stainless steel. The morphology, compositions of the interfaces and subsequent corrosive pitting were characterized by stereoscopy and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). Stress concentration, inclusions and high carbon levels were the main reasons of failure.
Comparative Study of the Degradation of the Green HDPE and Petrochemical HDPE in the Primary Recycling
Authors: Scienza Lisete Cristine , de Araújo Amanda Vecilla Chefer , Hubert Hariel Marçal Kops , Cândido Luis Henrique Alves , Martins Vinícius , Zattera Ademir José
Published: October 2020

Primary polymer recycling involves the reprocessing of defective parts and scraps in a processing line. The critical limitation for excessive use of primary recycling consists of the need to maintain the properties of the polymer above the required minimum level. The polymer degradation during the extrusion occurs by the combination thermal, oxidative and mechanical degradation. This work investigated the degradation of HDPE (High Density Polyethylene). Green HDPE (PV) and petrochemical HDPE (PN) were processed five times in a single-screw extruder and the flow rate, crystallinity and impact strength properties were evaluated. The increase in the number of reprocessing cycles increased the flow index and crystallinity values. The increase in the degree of crystallinity of the polymer, verified by the DSC analysis, evidenced the degradation of the material associated to the decrease of the size of the main chain (chain scission mechanism). The impact strength showed no significant change after five reprocessing cycles. Contrary variations were found in the crystallinity index considering the first and fifth processing, suggesting a change in the predominant mechanism of degradation.
From administrative hospital management to performancebased management: Paradigm shift at the Yaoundé Gynaeco-Obstetric and Pediatric Hospital, Cameroon
Authors: Angwafo III Fru , Chiabi Andreas , Bella Assumpta , Mah Evelyn M. , Dohbit Julius S. , Tafen Willy , Bih Geh Immaculate , Lele Samuel , Mba Charles N. , Mbopi-Kéou François-Xavier
Published: October 2020

The Yaoundé Gynaeco-Obstetric and Pediatric Hospital (YGOPH) faced challenges of high debts and sub-optimal care delivery. Performance-Based-Management (PBM) provides an environment of checks and balances, increased transparency, competition and autonomy, thereby improving clinical as well as financial indicators. We describe the transition from resource-based to PBM at the YGOPH over a seven-year period. There was an increase of 4.5% in OB/GYN and 8.1% in prenatal consultations, 8.4% in C-sections, 6.1% of children vaccinated, and 30.5% of women seen for family planning, 51.1% of people living with the Human Immunodeficiency Virus on treatment and 29.4% of indigent patients. These results occurred in spite of a 14% reduction in staff. Annual revenue increased by 5.75%. The share of hospital income from care on overall hospital revenue increased from 55.11% to 60.00%. With this self-financing PBM model, the hospital remains a social, humane and financially viable structure delivering improved quality care.
Prevalence and factors associated with poor self-rated health among communitydwelling older adults in Lomé (Togo) in 2019
Authors: Gbeasor-Komlanvi Fifonsi A. , Tchankoni Martin K. , Adjonko Ama B. , Zida-Compaore Wendpouire I.C. , Kouakou Nicolas K. , Belo Mofou , Agbonon Amegnona , Ekouevi Didier K.
Published: October 2020

The number of older adults is increasing worldwide, including in sub-Saharan Africa (SSA). However, there is a paucity of data on the overall health status of older adults living in SSA. To assess the prevalence and factors associated with poor Self-Rated Health (SRH) among community-dwelling older adults in Lomé, Togo, we conducted a cross-sectional study from January to June 2019 in Lomé among community-dwelling older adults aged 50 years and older. A 30- minute questionnaire was used to collect socio-demographic characteristics, medical history, patterns of medication use and use of herbal products and dietary supplements during a face-to-face interview. SRH was assessed using a single item: Overall, you would say that your health is… (1) excellent, (2) very good, (3) good, (4) fair and (5) poor with response fair or poor defining poor SRH. A total of 344 respondents with median age 63 years, (IQR: 55-72) were enrolled in the study. Women represented 57.6% of the sample. Overall prevalence of poor SRH was 56.4% (95%CI: 51.0-61.9) and was the highest among females (62.6% vs 47.9%; P=0.007) and participants 60 years (61.5% vs 51.1%; P=0.021). Female sex, aged ≥60 years, osteoarthritis, hospitalization within the 12 months preceding the survey, polypharmacy, and the use of herbal products were factors associated with poor SRH (P0.05). More than half of community- dwelling older adults had poor SRH in Lomé. Further studies are needed to guide policymakers in their efforts to design and implement meaningful policies to improve older adults health conditions.
Installation of Pedal-Operated Alcohol Gel Dispensers with Behavioral Nudges and Changes in Hand Hygiene Behaviors during the Covid-19 Pandemic: A Hospital-Based Quasi-Experimental Study
Authors: Wichaidit Wit , Naknual Sommanas , Kleangkert Nanta , Liabsuetrakul Tippawan
Published: October 2020

We conducted a quasi-experimental study and compared hand hygiene behaviors at potential pathogen transmission events among outpatient visitors (according to structured observations a trained enumerator) before and after installation of 12 pedal-operated alcohol gel dispensers with behavioral nudges (signs attached to the dispensers) at a tertiary hospital in southern Thailand during the COVID-19 pandemic. The enumerator observed 243 events during the pre-intervention period and 223 events during the postintervention period. Prevalence of hand hygiene was significantly different between the pre-intervention and post-intervention periods (0 vs 24 events, or 0% vs 11%, respectively; p-value <0.001). However, 21 of 24 hand hygiene events were of participants who came from outside the observation area, used the dispensers, then left. Nonetheless, the intervention might have helped to increase access to hand hygiene materials and created opportunities for hand hygiene among hospital visitors in general.
COVID-19 in Omani children with chronic Hemato-oncology diseases
Authors: Al Yazidi Laila
Published: October 2020

No abstract. This is a letter to the editor
Retained pelvic pin site debris after navigated total hip replacement
Authors: Kurmis AP
Published: October 2020

Once purely the domain of knee surgery, the use of computer-navigated techniques in total hip arthroplasty (THA) is becoming progressively more commonplace. As with the adoption of any new technology-assisted approach, the uptake of navigated THA utilization has heralded a new suite of technique-specific potential complications. One such example – not usually seen with conventional instrumented THA – pertains to complications related to the insertion and use of fixed pelvic array trackers. This case report describes the unusual circumstance of retained local bony debris generated through application of self-drilling, self-tapping iliac crest pins (for rigid navigation tracker placement) being mis-interpreted on advanced imaging - at a hospital site remote from the index surgery - as an aggressive, early-stage, chondrosarcomatous lesion. This case highlights the critical importance of both a general awareness of common imaging findings after navigated THA surgery (whereby tracker pins have been employed) and the value of 'hands on' clinical assessment of patients to allow correlation with suspicious imaging findings.
Pilomatricoma on 18F-fluorodeoxyglucose positron emission tomography-computed tomography: Peripheral mimic of an aggressive soft-tissue malignancy
Authors: Otunla Afolarin , Bradley Kevin
Published: October 2020

Pilomatricoma, also known as calcifying epithelioma of Malherbe, is a rare skin tumor originating from the hair follicle matrix. We report a case of pilomatricoma in a 50-year-old woman, presenting as a rapidly growing pretibial mass. Malignant pilomatricoma is associated with potentially fatal metastases and are clinically and histologically indistinguishable from benign pilomatricoma. Thus, an 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG PET/CT) scan was requested for staging, revealing marked FDG uptake restricted to the primary lesion and no evidence of separate disease. The purpose of this report is to demonstrate the importance of PET/CT in the staging of this FDG-avid tumor; the malignancy of which is often first revealed by metastases. Our case also demonstrates that pilomatricoma should be included in the differential diagnosis of a rapidly growing peripheral soft-tissue mass; conventionally, the domain of sarcoma.
Upregulated N6-Methyladenosine RNA in Peripheral Blood: Potential Diagnostic Biomarker for Breast Cancer
Authors: Xiao Han , Fan Xiaobo , Zhang Rui , Wu Guoqiu
Published: October 2020

Purpose An effective biomarker for the diagnosis of breast cancer (BC) and benign breast diseases (BBD) is crucial for improving the prognosis. We investigated whether N6-methyladenosine (m6A) can be a diagnostic biomarker of BC.Materials and Methods We detected the contents of peripheral blood m6A in 62 patients with BC, 41 patients with BBD, and 41 normal controls (NCs) using the colorimetric method. The relative expression of the m6A regulated genes methyltransferase-like 14 (METTL14) and fat mass and obesity-associated (FTO) was analyzed using quantitative real-time polymerase chain reaction.Results m6A in peripheral blood RNA was significantly higher in patients with BC than that in patients with BBD (p < 0.001) or the NCs (p < 0.001). m6A was closely associated with the disease stage (from stage 0 to stage I-IV, p=0.003). The receiver operating characteristic curve of m6A contained an area under the curve (AUC) value of 0.887 in BC, which was greater than that of carcinoembryonic antigen (CEA) or carbohydrate antigen 153 (CA153). The combination of m6A, CEA, and CA153 improved the AUC to 0.914. The upregulated and downregulated mRNA expression of METTL14 and FTO, respectively, might contribute to the increase of m6A in patients with BC. m6A combined with METTL14 and FTO improved the AUC to 0.929 with a specificity of 97.4% in the peripheral blood of patients with BC.Conclusion The peripheral blood RNA of m6A might be a valuable biomarker for the diagnosis of BC.
USO DEL DIMINUTIVO EN ECUADOR: SIGNO DE CONFIANZA EN LA RELACIÓN MÉDICO-PACIENTE, ENFERMERO-PACIENTE
Authors: Estupiñan-Lince María Lorena
Published: October 2020

En Ecuador, utilizar diminutivos en el lenguaje formal y familiar es muy popular y por lo tanto también en ámbitos como el área de la salud. Este estudio tiene como objetivo identificar los principales diminutivos utilizados por el personal de la salud con los pacientes adultos y las razones por las cuales se emplean. Además, conocer la opinión de los pacientes respecto al uso de los diminutivos en las consultas médicas. Por medio de una encuesta en línea se obtiene la información para comprobar la hipótesis. Los resultados permiten conocer que el diminutivo más utilizado según el personal de la salud ecuatoriano es "un ratito" y el diminutivo más escuchado por los pacientes es parte de la frase "deme su bracito". Las principales razones por las cuales el personal de la salud utiliza los diminutivos en las consultas son: 1. Para dar confianza a sus pacientes, 2. por cortesía. Al respecto, la opinión de los pacientes está dividida: primero están aquellos que efectivamente cuando escuchan diminutivos se sienten en un ambiente de confianza, luego, los que manifiestan que les da igual escuchar diminutivos, y por último los que prefieren que no se utilicen diminutivos con ellos.

Palabras clave: diminutivos, personal de la salud, Ecuador, signo, confianza, pacientes, relación.
Pengaruh Adversity Intelligence, Motivasi Belajar Terhadap Kesiapan Belajar
Authors: Arika Palapa  , Arifin Moh Zaenal , Hartoyo Hartoyo
Published: October 2020

The specific purpose of this study was to examine the effect of Adversity Intelligence of cadets participating in the seafaring expertise test and learning motivation of cadets participating in the seafaring expertise test on study readiness both partially and collectively. This study used a sample of 62 cadets participating in the pre-prala seafarer expertise test in the nautical department. The sampling technique in this study was nonprobability sampling with a purposive sampling method. Based on the research results, it can be concluded as follows: (1) adversity intelligence has an effect on learning readiness, (2) learning motivation has a positive and significant effect on learning readiness, (3) Adversity Intelligence affects learning motivation, ( 4) Adversity Intelligence and learning motivation together have an effect on learning readiness.