bluuebunny/crossref_metadata_2025 huggingface dataset:
Large-Scale Screening of HCMV-Seropositive Blood Donors Indicates that HCMV Effectively Escapes from Antibodies by Cell-Associated Spread
Authors: Falk Jessica Julia , Winkelmann Martina , Laib Sampaio Kerstin , Paal Caroline , Schrezenmeier Hubert , Alt Mira , Stanton Richard , Krawczyk Adalbert , Lotfi Ramin , Sinzger Christian
Published: September 2018

Immunoglobulins are only moderately effective for the treatment of human cytomegalovirus (HCMV) infections, possibly due to ineffectiveness against cell-associated virus spread. To overcome this limitation, we aimed to identify individuals with exceptional antibodies in their plasma that can efficiently block the cell-associated spread of HCMV. A Gaussia luciferase-secreting mutant of the cell-associated HCMV strain Merlin was generated, and luciferase activity evaluated as a readout for the extent of cell-associated focal spread. This reporter virus-based assay was then applied to screen plasma samples from 8400 HCMV-seropositive individuals for their inhibitory effect, including direct-acting antiviral drugs as positive controls. None of the plasmas reduced virus spread to the level of these controls. Even the top-scoring samples that partially reduced luciferase activity in the screening assay failed to inhibit focal growth when reevaluated with a more accurate, immunofluorescence-based assay. Selected sera with high neutralizing capacity against free viruses were analyzed separately, and none of them prevented the focal spread of three recent clinical HCMV isolates nor reduced the number of particles transmitted, as demonstrated with a fluorescent Merlin mutant. We concluded that donors with cell-to-cell-spread-inhibiting plasma are nonexistent or extremely rare, emphasizing cell-associated spread as a highly efficient immune escape mechanism of HCMV.
Effect of Aeration Rates and Filter Media Heights on the Performance of Pollutant Removal in an Up-Flow Biological Aerated Filter
Authors: Ren Jiehui , Cheng Wen , Wan Tian , Wang Min , Zhang Chengcheng
Published: September 2018

The biological aerated filter (BAF) is an effective biological treatment technology which removes the pollutants in municipal wastewater secondary treatment. However, we still know little about the interaction between the pollutants removal and microbes within the BAF. In this study, we used an up-flow BAF (UBAF) reactor to investigate the relationships between the pollutants removal and microbial community structure at different aeration rates and filter media heights. The microbial community of biofilm was analyzed by Illumina pyrosequencing. Our results showed that the UBAF achieved a better removal efficiency of chemical oxygen demand (COD), NH4+-N, NO3−-N, and total phosphorus (TP) at an aeration rate of 65 L/h. In addition, the COD and NH4+-N removal mainly occurred at 0–25 cm height of filter media. The microbial community structure in the UBAF demonstrated that the relative abundance of the Planctomycetes and Comamonadaceae at 10 cm height of filter media were 11% and 48.1%, respectively, proportions significantly higher than those under others treatments. Finally, the changes in relative abundance of Proteobacteria, Planctomycetes, and Nitrospirae likely explained the mechanism of nitrogen and phosphorus removal. Our results showed that suitable conditions could enhance the microbial community structure to achieve a high pollutants removal in the UBAF.
Coupling of Ultrasonic and Photometric Techniques for Synchronous Measurements of Unconfined Turbidity Currents
Authors: Wilson Richard I. , Friedrich Heide
Published: September 2018

By synchronizing data collection, such as photometric and ultrasonic Doppler profiling (UVP) measurement techniques, new insights can be obtained into environmental flows, such as highly dynamic turbidity currents. We introduce a combined experimental setup, which ultimately allows a time reduction in testing programmes, and discuss the measurement advances with the help of four surface conditions we tested for unconfined turbidity currents: (a) a smooth surface; (b) a smooth surface with an obstacle present; (c) a rough surface; and (d) a rough surface with an obstacle present. We show that data from both measurement techniques indicate that a rough surface reduces global current velocities and the magnitude of turbidity current phenomena, including Kelvin-Helmholtz instabilities and lobe-and-cleft formation. However, by coupling the techniques, photometric data give valuable insight into the spatial development of instabilities, such as the grouping of lobe and cleft formations. The presence of an obstacle causes local regions of an increased and decreased velocity, but does not affect the global current velocity. Additionally, the obstacle created three local intensity maxima upstream, dissipating to two maxima downstream, supporting the presence of local eddies. The study shows that the combination of UVP and photometry is an effective way forward for obtaining detailed qualitative and quantitative insights into turbulent flow characteristics and we highlight the potential for future research.
Synthesis of indolo[1,2-c]quinazolines from 2-alkynylaniline derivatives through Pd-catalyzed indole formation/cyclization with N,N-dimethylformamide dimethyl acetal
Authors: Arcadi Antonio , Cacchi Sandro , Fabrizi Giancarlo , Ghirga Francesca , Goggiamani Antonella , Iazzetti Antonia , Marinelli Fabio
Published: September 2018

An efficient strategy for the synthesis of 6-unsubstituted indolo[1,2-c]quinazolines is described. The Pd-catalyzed reaction of o-(o-aminophenylethynyl) trifluoroacetanilides with Ar–B(OH)2 afforded 2-(o-aminophenyl)-3-arylindoles, that were converted to 12-arylindolo[1,2-c]quinazolines by adding dimethylformamide dimethyl acetal (DMFDMA) to the reaction mixture after extractive work-up. This reaction outcome is different from the previously reported Pd-catalyzed sequential reaction of the same substrates with Ar–I, Ar–Br and ArN2+BF4−, that afforded 12-arylindolo[1,2-c]quinazolin-6(5H)-ones. Moreover, 12-unsubstituted indolo[1,2-c]quinazolines can be obtained both by reacting 2-(o-aminophenyl)indoles with DMFDMA or by sequential Pd-catalyzed reaction of o-(o-aminophenylethynyl)aniline with DMFDMA.
Characterizing the Performance of the NIRC2 Vortex Coronagraph at W. M. Keck Observatory
Authors: Xuan W. Jerry , Mawet Dimitri , Ngo Henry , Ruane Garreth , Bailey Vanessa P. , Choquet Élodie , Absil Olivier , Alvarez Carlos , Bryan Marta , Cook Therese , Castellá Bruno Femenía , Gonzalez Carlos Gomez , Huby Elsa , Knutson Heather A. , Matthews Keith , Ragland Sam , Serabyn Eugene , Zawol Zoë
Published: September 2018

The NIRC2 vortex coronagraph is an instrument on Keck II designed to directly image exoplanets and circumstellar disks at mid-infrared bands L′ (3.4–4.1 μm) and M

s
(4.55–4.8 μm). We analyze imaging data and corresponding adaptive optics telemetry, observing conditions, and other metadata over a three-year time period to characterize the performance of the instrument and predict the detection limits of future observations. We systematically process images from 359 observations of 304 unique stars to subtract residual starlight (i.e., the coronagraphic point-spread function) of the target star using two methods: angular differential imaging (ADI) and reference star differential imaging (RDI). We find that for the typical parallactic angle (PA) rotation of our data set (∼10°), RDI provides gains over ADI for angular separations smaller than 0.″25. Furthermore, we find a power-law relation between the angular separation from the host star and the minimum PA rotation required for ADI to outperform RDI, with a power-law index of −1.18 ± 0.08. Finally, we use random forest models to estimate ADI and RDI post-processed detection limits a priori. These models, which we provide publicly on a website, explain 70%–80% of the variance in ADI detection limits and 30%–50% of the variance in RDI detection limits. Averaged over a range of angular separations, our models predict both ADI and RDI contrast to within a factor of 2. These results illuminate important factors in high-contrast imaging observations with the NIRC2 vortex coronagraph, help improve observing strategies, and inform future upgrades to the hardware.
Proxy Wars and the Role of Intelligence Services in the Current Middle-East
Authors: Kraus Josef
Published: September 2018

The paper deals with the concept of proxy wars in the region of the Middle-East and the role of intelligence services in it. In the current conflicts in Syria, Iraq and Yemen, many external actors and powers interfere using (not only) their intelligence services for the defence of their national interests in afflicted states, often even combating each other on a territory of a different state. The main goal of the paper is to introduce the concept of proxy war and analyse the role of intelligence services in the ongoing conflicts in the defined area.
Hydnophanerochaete and Odontoefibula, two new genera of phanerochaetoid fungi (Polyporales, Basidiomycota) from East Asia
Authors: Chen Che-Chih , Wu Sheng-Hua , Chen Chi-Yu
Published: September 2018

Two new genera with phylogenetic affinities to Phanerochaete s.l. are presented, namely Hydnophanerochaete and Odontoefibula. The generic type of Hydnophanerochaete is Phanerochaeteodontoidea. Odontoefibula is established based on a new species: O.orientalis (generic type). Both genera have effused basidiocarps with odontioid hymenial surface, simple-septate generative hyphae, cystidia lacking, clavate basidia and ellipsoid basidiospores that are smooth, thin-walled, inamyloid, non-dextrinoid and acyanophilous. Hydnophanerochaete is additionally characterised by a compact texture in the subiculum with thick-walled generative hyphae and quasi-binding hyphae. Odontoefibula has a dense texture of subiculum with thin- to slightly thick-walled hyphae and further a dark reddish reaction of basidiocarps when treated with KOH. Multi-marker phylogenetic analyses based on sequences, inferred from the ITS+nuc 28S+rpb1+rpb2+tef1 dataset, indicate that Hydnophanerochaete and Odontoefibula are placed in the Meruliaceae and Donkia clades of Phanerochaetaceae, respectively. Phanerochaetesubodontoidea is a synonym of P.odontoidea, according to morphological and molecular evidence.
La Réunion et le mouvement de rétrocession de l’île Maurice à la France (1918-1921)
Authors: Fageol Pierre-Éric
Published: September 2018

Dans la logique des impacts politiques de la Première Guerre mondiale dans les Empires, cet article met en perspective le mouvement de rétrocession de l’île Maurice à la France entre 1918 et 1921. Influencé par les débats des conférences de paix autour du droit des peuples à disposer d’eux-mêmes, le mouvement est défendu par les Créoles mauriciens d’origine française qui avancent l’idée d’un retour de l’ancienne « île de France » sous la responsabilité des autorités coloniales françaises. Les lobbies mauriciens ont été suffisamment actifs pour permettre un élargissement des débats en France et au Royaume-Uni tout comme dans leurs empires respectifs. Il s’agit donc de montrer la force d’une communication intercoloniale qui influe sur les modèles identitaires des colonies concernées.
Syndicalisme international : pistes de réflexion pour de nouvelles campagnes
Authors: Allen Nick
Published: September 2018

Nick Allen est un syndicaliste américain, permanent international du grand syndicat des services nord-américain, le SEIU ( Service Employees International Union ). Dans ce texte, il propose de repenser la solidarité des travailleur.ses et l’action face aux multinationales. Il situe au cœur de sa réflexion l’action syndicale internationale sur les questions de migration, des chaînes de valeur et de la finance.
Construire une alliance transnationale : l’exemple de B2S
Authors: Cottin-Marx Simon
Published: September 2018

Depuis 2012, le ReAct accompagne les syndicalistes de la multinationale B2S 1 dans leur organisation locale et transnationale afin d’amener la direction du groupe à négocier avec les salarié.es pour l’amélioration de leurs conditions de travail. Marielle Benchehboune est « organisatrice » dans cette association et a participé à l’amorçage et au développement de l’alliance transnationale des salarié.es français.es et marocain.es du groupe B2s.
Cyberbullying: An Unceasing Threat in Today's Digitalized World
Authors: Waller Andrew P. , Lokhande Akshay P. , Ekambaram Vijayabharathi , Deshpande Swapna N. , Ostermeyer Britta
Published: September 2018

Cyberbullying, the use of electronic communication to bully another person with intimidation or threatening messages, has become an ever-increasing public safety concern. Lifetime bullying incidences have doubled in the past 10 years. Although all youth are at risk, the risk is significantly higher for minority and disabled children, adolescent girls, and youth with poor interpersonal relationships and low self-esteem. Enhanced by modern technology, cyberbullies experience an online disinhibition effect due to distance from the victim. Risk factors for cyberbullying include substance use, being raised by authoritarian parenting style, and poor relationship bonds. Because one of the most significant protective factors against cyberbullying victimization is social support, interventions have focused on fostering supportive environments. This article reviews behaviors, epidemiology, characteristics of victims and perpetrators, impact on individuals, and prevention and interventions related to cyberbullying.

[
Psychiatr Ann.
2018;48(9):408–415.]
Effect of Methods of Changing in Focusing Ratio on Line Geometry in Aerosol Jet Printing
Authors: Arsenov Pavel V. , Efimov Alexey A. , Ivanov Victor V.
Published: September 2018

In this article, a study is presented of the effect of the focusing ratio (FR) on the line geometry in aerosol printing process. The FR was defined as the ratio of sheath flow to aerosol flow. The FR was varied from 1 to 20. In the experiment, different nozzles were used, with outlet diameter of 100, 150 and 300 μm. It was established that in increasing FR from 1 to 20 by reducing the aerosol flow with constant sheath flow rate, line width and thickness are reduced in more than 40 and 10 times respectively. It is also found that by increasing the FR from 2 to 8 by changing only sheath flow with constant aerosol flow rate, line width is reduced from 125 to 75 μm, while line thickness is increased from 7.1 to 10.3 μm. It is shown that this feature is related to the quantity of the matter deposited on the substrate, which is directly related to aerosol flow. The achieved result is important for designing current-carrying lines of electronic circuits which require a specific aspect ratio and high circuit element density
Metallic Materials Prepared by Selective Laser Melting: Part Orientation Issue
Authors: Fousova Michaela , Dvorský Drahomír , Lejček Pavel , Vojtěch Dalibor
Published: September 2018

This paper shows part orientation issue in the process of Selective Laser Melting (SLM) at four examples of metallic materials (Fe, stainless steel 316L, TiAl6V4 alloy and AlSi11Mg alloy). Horizontally and vertically oriented samples differ in their mechanical properties, especially in plasticity. The causes of these differences are related to a thermal history, microstructural features and porosity. Depending on a particular material, individual effects are manifested under different extents.
Methodology of Technological Adaptation Applied to Powder Rolling
Authors: Polyakova Marina , Golubchik Eduard
Published: September 2018

Powder rolling is used for manufacturing long-length strip. For obtaining the product with high green density it is necessary to ensure shear strain in the deformation zone. Based on the principles of technologic adaptation the dual roll closed caliber with adaptively changed rigidity was constructed. It consists of upper bandage with shoulder, bottom bandage with groove in which the set of three rings (two aside and one central) is located. The pass is arranged by aside rings and outside surface of the central ring forming closed caliber while interacting with the shoulder of the upper bandage. The caliber output is equal to zero and the broadening at rolling is fully excluded. Such construction of the tool makes it possible to achieve high level of hydrostatic stress of tensor simultaneously with intensification of shear strains resulting in practically nonporous rolled strip. Taking into consideration peculiarities of calibre rolling the new criterion was proposed. This criterion enables to characterize roll system for each material, incompact materials in particular, considering retraction ability, to assess and identify the final square of the rolled material at different caliber configuration. Dependence of maximum value of powdered rolled strip thickness on dual roll closed caliber retraction surface value at different rolled strip width is presented.
Room Temperature Compression Behavior of Mixtures of Carbonyl Iron Powder and HDPE
Authors: Deorukhkar Bharat D. , Doifode Devanand S. , Date Prashant P. , Alexandrov Sergei
Published: September 2018

In present research work, metal injection molded cylindrical samples containing the mixture of carbonyl iron powder and high-density polyethylene (HDPE) were compressed at various strain rates. Three mixtures of carbonyl iron powder and HDPE were prepared to contain 80 %( Material A), 86 %( Material B) and 92 %( Material C) metal powder by weight. Compression tests were performed on the cylindrical samples at different crosshead velocities of Universal Testing Machine varying from 0.6-25 mm/min. True stress-true strain behavior of these samples under uniaxial compression test was studied. Based on these curves, polynomial equations were formulated to describe the plastic deformation behavior of the various mixtures at various cross head velocities. The Material C samples showed higher strength as compared to samples from the other two materials. However, Material A showed superior deformation behavior.
Polymer Foams Based on Low Density Polyethylene/Ethylene Vinyl Acetate/Ground Tire Rubber (LDPE/EVA/GTR): Influence of the GTR Particle Size and Content on the Cellular Morphology and Density of the Final Foamed Compounds
Authors: Soriano-Corral Florentino , Hernández-Gámez José F. , Durón-Sánchez Lyndon H. I. , Ramos de Valle Luis Francisco , Lozano-Estrada Myriam , Soto-Lara Yair A.
Published: September 2018

Addition of different contents of ground tire rubber (GTR) of different particles size in crosslinked-foamed compounds based on low density polyethylene (LDPE)/ethylene vinyl acetate (EVA) was studied. Compounds were made by melt mixing in an internal mixer at 100°C and 60 rpm. Trigonox 145-45B as crosslinking agent, azodicarbonamide (ADC) as chemical blowing agent (CBA) and ZnO/SiO2as foaming co-agents, were used. GTR of 149, 74, and 44 μm particle size was incorporated as “cell nucleating agent”, each particle size at 5, 10, and 20 phr. Morphological parameters such as average cell size (d), cell size distribution and cellular density (NC) were evaluated from images acquired by scanning electron microscopy (SEM). The results obtained from the SEM characterization show a significant reduction ofd, a significance increment onNC, up to 5.81*105to 3.62*107cells/cm3and a better homogenization of the cell size distribution in the foamed compounds with high GTR contents of the smaller particle size.
Study on the Influence of the Wastes from Cashew Industry on Environmentally Friendly Bricks
Authors: de Araújo Francisca Pereira , Osajima Josy Anteveli , de Souza João Sammy Nery , Furtini Marcelo Barbosa
Published: September 2018

Soil-cement bricks are sustainable and economically viable alternatives due to the possibility of residue utilization. CNSL (Cashew nut shell liquid ) is an example of residue from the cashew industry that can be reused in many applications. Therefore, the present work had as its objective to produce soil-cement bricks having CNSL as a constituent of the formulation. The samples were obtained from the mixture of pure CNSL, soil and cement (1:10). The soils used in the research were extracted from the south of the state and the mixture was pressed in a modular manual press. The samples were submitted to resistance and permeability tests and the results related to resistance and compression showed that the bricks presented an average of 2,3 MPa and were in accordance with what is suggested by NBR 8491/12. The presence of CNSL also altered the permeability of the material which was obtained. Hence, one may conclude that the presence of CNSL satisfactorily influences upon the properties of soil-cement bricks.
Characterization of Kaolin Residues from the Jarí Valley Reservations Provided by Cadam S/A Company
Authors: Chaves Alexsandra Cristina , da Silva I.V. , da Silva A.L. , Neves G.A. , Oliveira Danielle Nascimento Silva
Published: September 2018

The ceramic industry is one of the most important productive chains of the State of Pará, generating both money and employment. Kaolin has many industrial applications and new uses are constantly surveyed. Although the extraction and processing of kaolin contribute to the economy growth, the activity also provokes serious environmental issues. Being aware of the environmental problem caused by the inadequate decomposition of kaolin residues from the beneficiation process of these minerals, which pollute and attack the environment, this paper aims the chemical, physical and mineralogical characterization of the kaolin residue from the post-treatment disposal provided by CADAM S/A company. The main oxides in the residues were SiO2and Al2O3. In the X-ray diffraction analysis it was verified that the kaolin residue is basically formed by kaolinite and quartz, in the particle size analysis it was observed that the medium size of the particle was of 1,77 μm.
In Situ Hydration of Sulfoaluminate Cement Mixtures Monitored by Synchrotron X-Ray Diffraction
Authors: Rossetto Cleusa M. , Ichikawa Rodrigo Uchida , Martinez Luís Gallego , Carezzato Geraldo L. , Carvalho Alexandre M.G. , Turrillas Xavier
Published: September 2018

Mixtures of calcium sulfoaluminate and Portland clinkers with gypsum were hydrated with deionized water. The pastes were introduced in 0.7 mm borosilicate capillary tubes and kept at 40 oC while diffraction patterns were collected every 35 s for approximately 3 hours with a monochromatic radiation of 12 keV at the XRD1 beamline of the Laboratório Nacional de Luz Síncrotron (LNLS) in Campinas, SP - Brazil. The main crystalline phases (C2S, C3S, ettringite, ye’elemite and gypsum) involved in the hydration were quantified by Rietveld analysis. The most noticeable fact was the absence of portlandite as a crystalline precipitate, most likely due to the capture of calcium ions to form ettringite.
Study of Hybrid Membranes Prepared with the Addition of Calcium Chloride
Authors: Medeiros Keila Machado , Lima Diego Farias , Lima Carlos Antônio Pereira , Araújo Edcleide Maria , Lira Helio Lucena
Published: September 2018

In this work, hybrid membranes were obtained with the addition of calcium chloride (CaCl2). Hybrids were obtained by the melt intercalation method. Membranes were prepared by phase inversion technique. Hybrid and hybrid membranes were characterized by differential scanning calorimetry (DSC). The DSC curve of the polymer and polymer membrane was changed by addition of the clay, increasing the degree of crystallinity. For all membranes, it was observed the existence of two endothermic peaks corresponding to the two crystalline phases of the polymer characteristics, in the range of 220 °C related to the alpha phase and, in the range of 210 °C related the gamma phase. In addition, there was the appearance of an endothermic peak at about 70 °C, related to the temperature of the dry polymer glass transition. The addition of CaCl2changed the crystalline behavior of hybrids, becoming less evident the nucleating effect of the clay.
Characterization of PET-Silver Nanocomposite Filaments
Authors: Guerra Marcos Antônio , Swerts Jeferson Prado , Funcia Mei Abe , Mariano Neide Aparecida , Campos Maria Gabriela Nogueira
Published: September 2018

Polyethylene terephthalate (PET) fiber is a very versatile fiber that can be produced with different properties, such as antimicrobial activity. This study aims to synthesize antimicrobial PET filaments incorporated with silver nanoparticles immobilized in silica (NPAg-Si) by bulk additive method. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) characterized the obtained filaments at concentrations (w/w) of 0.008%, 0.016%, 0.032%, 0.047% and 0.063% NPAg-Si, in order to identify the nanoparticles and analyze their dispersion in the polymeric matrix. Moreover, thermogravimetric analysis (TGA) was carry out to confirm the presence and concentration of the silver nanoparticles in the filaments as well as the thermal stability of the nanocomposites. The bulk addition method was efficient to produce PET-Silver filaments with silver nanoparticles homogeneously dispersed in the PET matrix.
Effect of Drying Temperature in Biopolymeric Films of Cassava Starch and its Effect on Wettability, Water Vapor Barrier and Mechanical Properties
Authors: Oliveira Victor Rafael Leal , Monteiro M.K.S. , Santos F.K.G. , Leite R.H.L. , Aroucha E.M.M.
Published: September 2018

Coating technologies with biopolymeric films of low cost and high efficiency are effective in maintaining the chemical and sensory characteristics and shelf-life extension of several fruits.Films of cassava starch/glycerol were synthesized at different temperature and time conditions (25oC / 60h, 40oC / 5h, 60oC / 3h and 80oC / 2h) in order to decrease the drying time of the filmogenic solutions.SEM analysis (scanning electron microscopy), WVP (water vapor permeability), wettability and mechanical properties were evaluated in order to identify morphological and structural changes in the polymeric matrix in different conditions.Changes in temperature and drying time significantly reduced the roughness and affected the barrier characteristics, effectively improving tensile strength. A reduction of more than 90% in the drying time was identified.
Hydrothermal Synthesis of Zeolite a Using Non-Calcined Diatomite
Authors: de Carvalho Alexandre Fontes Melo , da Costa Tiago Roberto , de Figueredo Gilvan Pereira , Alves José Antônio Barros Leal Reis , Santiago Rodrigo César , de Freitas Melo Marcus Antônio , de Araújo Melo Dulce Maria
Published: September 2018

Optimization and reduction of zeolite A synthesis costs are the focus of several studies. Attention has been given to the use of residues and natural materials rich in Si and Al, such as diatomite. Diatomite needs to be calcined above 500°C to be used, which increases processing costs. This study aimed at evaluating the use of diatomite without calcination in preparing zeolite A. Alkaline hydrothermal synthesis melting and 24 h of crystallization were carried out. The materials were characterized by XRD (X-ray powder diffraction), XRF (X-ray fluorescence), BET (N2physisorption) and SEM (Scanning Electron Microscopy). XRD data and refinement show that the obtained material presents 99.84% crystallinity, average crystallite size of 54.92 nm, and a semi-quantitative percentage of 79% zeolite A. SiO2and Al2O3contents in the prepared sample proved the ratio SiO2/Al2O3= 2. The micrographies show cubic particles and agglomerated sodalite.
Effect of Niobium and Heat Treatment on the Microstructure and Mechanical Properties of SAE 8620 Steel
Authors: de Macêdo Neto José Costa , Duarte Vieira Marcelo , Silva Guedes Ana Emília Diniz , Neto João Evangelista , de Freitas Bruno Mello , Moreira Guilherme Santos , Cruz Lucas Carvalho , Dias Waldeir Silva , Girard Nicolas , Santiago Eliseu Lopes Gomes , do Nascimento Nayra Reis , dos Santos Marcos Dantas
Published: September 2018

An interest in the search for materials with reduced thicknesses, high mechanical resistance and low density has been increasing by the industry. The addition of niobium in micro-alloyed steels in the automotive industry is an alternative for obtaining light and resistant materials. The objective of this work was to verify the influence of the niobium and the heat treatment of normalizing in the microstructure and hardness of the steel SAE 8620. Also the behavior of the cementation in the steel was studied. It was verified that the removal of the normalization heat treatment did not affect the microstructure and the hardness of the steel with the niobium in relation to the steel without niobium and normalization. The cemented layer for the steel with niobium presented a greater microhardness to the depth in relation to steel without niobium.
Effects of Different Annealing Times on Microstructure and Tensile Properties of Joints Welded 5052 Aluminum Alloy in Marine Industry
Authors: de Macêdo Neto José Costa , de Oliveira Josiel Bruno , Ribeiro Mateus Reis , Silva Guedes Ana Emília Diniz , Almeida Rodrigues Reinaldo , Silva Raimundo Nonato Alves , do Nascimento Nayra Reis , Neto João Evangelista , Barreda Eduardo Rafael , Martins João Carlos , de Freitas Bruno Mello
Published: September 2018

The welding process is widely used for boat building, but the process for aluminum (base metal) is affected by the welding heat may affect the mechanical properties of the joint. The objective of this study was to evaluate the effect of different annealing times of welded joints of naval aluminum 5052 by MIG. The thermal annealing treatments were 30 and 60 min. at 300 °C. For the evaluation of the influence of different times of annealing on the properties were carried out tensile, hardness and their microstructures observed by optical microscopy. The heat treatment using 30 min. at 300 °C got higher mechanical property. The tensile test showed a higher value for the treatment 30 min. The microhardness showed a higher value for the weld pool of treatment 30 minu.. Microscopic analysis showed microstructural changes after annealing.
Limit Strains Analysis of Advanced High Strength Steels Sheets Based on Surface Roughness Measurements
Authors: da Silveira Lílian Barros , Moreira Luciano Pessanha , da Silva Ladario , Santos Rafael Oliveira , da Silva Fabiane Roberta Freitas , Cardoso Marcelo Costa , dos Santos Freitas Maria Carolina
Published: September 2018

The limit strains of dual-phase steels DP600 and 800 were evaluated in this work with a localization model formulated in plane-stress conditions using elasto-plastic constitutive equations. In this model, a geometrical imperfection parameter is defined from the sheet nominal thickness, initial ferrite grain size and average surface roughness. The proposed identification procedure provided a more physically meaning for this parameter and at best more conservative predictions in the drawing Forming Limit Curve (FLC) range of both investigated dual-phase steels. Nevertheless, the corresponding limit strains in the biaxial stretching region are underestimated with the present theoretical model. Thus, more detailed anisotropic yield function and hardening descriptions must be implemented to improve the accuracy of the FLC prediction of advanced high strength steels.
Determination of Mechanical Properties for Microhardness Mapping in a 5052 Aluminum Alloy Welded by Mig Process
Authors: de Macêdo Neto José Costa , Silva Juarez Viégas , dos Santos Moreira Guilherme , Neto João Evangelista , Silveira Flavio , de Freitas Bruno Mello , Silva Guedes Ana Emília Diniz , Almeida Rodrigues Reinaldo , Kimura Solenise Pinto Rodrigues , do Nascimento Nayra Reis , Barreda Eduardo Rafael , Silva Raimundo Nonato Alves
Published: September 2018

Aluminum alloys are widely used in shipbuilding, it is a material with good mechanical strength, high corrosion resistance and good conformation. In this study we used the filler metal 5183 aluminum alloy, groove angle 80°, root opening 0,5mm, stick-out 12 a 14mm, voltage 23V, torch 99,99%Ar, transfer mode Pulsed, current 220A, wire speed 30cm/min, gas flow 25l/min. The aim of this study was to research the mechanical strength in a welded joint naval 5052 aluminum alloy welded by Metal Inert Gas-MIG process using a mapping microhardness and software images. They were also carried out the tensile test, chemical analysis of the studied alloy and optical microscopy. The results of microhardness showed that the weld pool showed lower values. Optical microscopy showed that the weld pool had bubbles and the tensile test was presented fracture in the welded joint.
Effect of Solution Annealing Time on the Microstructure and Corrosion Resistance of Duplex Stainless Steel
Authors: de Rezende Stephania Capellari , Cronemberger Maria Eurenice Rocha , Silva Rodrigo , Rovere Carlos A. Della , Kuri Sebastião Elias , de Sousa Lucíola Lucena , Mariano Neide Aparecida
Published: September 2018

The formation of intermetallic phases during thermal treatments is a decisive point for the performance of duplex stainless steels, which may prevent the obtaining or provoke degradation of their properties. This paper presents an investigation on the corrosion resistance of duplex SAF 2205 steel as received and after solution annealing treatment. The objective was to evaluate the correlation between the solution annealing time, the resulting microstructural changes and the corrosion resistance of the steel through electrochemical tests of cyclic potentiodynamic polarization and double-cycle potentiokinetic reactivation (DL-EPR). The heat treatments were performed at 1100° C for 30, 120 and 240 min with subsequent air cooling. The results of the DL-EPR showed that although there was no presence of intermetallic phases even with the absence of intermetallic phases, the solution annealing time influenced the degree of chromium depletion of the samples, so that with the increase of time, there was an increase in the degree of chrome depletion.
Influence of Strain Amplitude on the Functional Properties and Aging at Room Temperature of a Superelastic NiTi Alloy
Authors: Mendes Rodrigues Mariana Carla , Soares Guilherme Corrêa , de Arruda Santos Leandro
Published: September 2018

The effects of strain amplitude variation on the functional properties of a superelastic NiTi wire were investigated in terms of critical stress to induce martensite, accumulated residual strain, dissipated energy, lower plateau stress, and stress at maximum strain. Wire specimens were subjected to training by pseudoelastic cycling, being mechanically strained up to strain amplitudes of 4, 6, 8, 10, 12 and 14%. A total of 20 cycles were performed at each condition at room temperature and strain rate of 10-3s-1. In order to assess if the wires were able to maintain stable their functional properties after training, samples subjected to cycling at 8 and 14% strain amplitudes were aged at room temperature and retested. The results showed that the functional properties tend to stabilize faster when the alloy is subjected to lower strain amplitudes. It was observed that part of the functional properties was recovered if aged at room temperature.
Study of the Correlation between Microstructure and Corrosion Resistance of the AZ91D Magnesium Alloy
Authors: Antunes Renato Altobelli , de Oliveira Mara Cristina Lopes , de Castro Ferraz Lucas Costa , dos Reis Gonçales Letícia , Correa Olandir Vercino
Published: September 2018

The aim of the present work was to study the influence of beta phase precipitates content and distribution on the corrosion behavior of the AZ91D magnesium alloy, using samples subjected to solution annealing and aging. The morphology of the beta phase was observed using optical microscopy and scanning electron microscopy. The volume fraction of each phase was also determined. Potentiodynamic polarization tests and immersion tests were carried out, indicating an increase of the corrosion resistance with the volume fraction of the beta phase and its distribution on the grain boundaries of the alpha-phase. Solution annealed samples were more susceptible to corrosion.
Evaluation of Spheroidization on Erosive Wear of ASTM A106 Steel Used in Heat Exchangers
Authors: da Rocha M.R. , Arnt A.B.C. , Angioletto Elidio , Virgínia H.A. , Ugioni G.B. , Teixeira A.
Published: September 2018

One of the problems encountered in heat exchangers working at high temperatures is the degradation caused by erosive processes, especially in coal-fired power plants. One of the factors that contribute to the degradation of the material is the microstructural changes, like the spheroidization of the carbides. This reduces the mechanical strength of the material and consequently accelerates its wear process. The objective of this work was to evaluate the effect of spheroidization under erosive wear conditions on ASTM A106 steel. The samples were submitted to different treatment times and temperatures, aiming to generate spheroidization in the samples, later submitted to erosive wear tests. Loss of mass, microstructures and mechanical strength were evaluated from the microhardness, with the evolution of the spheroidization process. The samples with higher level of spheroidization, obtained in the temperatures of 730 ° C in times above 50 hours presented greater reduction of hardness that resulted in greater losses of mass. In general, with the increase of spheroidization, there is reduction of mechanical resistance and erosive erosion, but with a gradual reduction in wear rate. This is possibly due to the increased ductility / toughness of the matrix, which delays the process of debris formation on the ASTM A106 steel surface during the hot erosive process.
Comparison between Magnetic Anisotropy Energy and a Parameter to the Assessment of Magnetic Property of Electrical Steel
Authors: Felix R.A.C. , da Rosa R.L.O. , Brandão Luiz P.
Published: September 2018

Alternative methods of quantitative texture analysis are applied to characterize the non-oriented grain electrical steels (NOG) in relation to their magnetic properties. Magnetic anisotropy energy (Ea) and A parameter are two models based on crystallographic texture that generates global parameters that can be used to predict the magnetic properties of NOG steels. In this work, these two models were used to evaluate the magnetic polarization and compared between themselves to realize which one best correlates to this property.
Recycling Chips of Stainless Steel by High Energy Ball Milling
Authors: de Sales Pereira Mendonça Claudiney , dos Santos Ribeiro Vander Alkmin , Junqueira Mateus Morais , Sachs Daniela , Oliveira Leonardo Albergaria , Melo Mírian de Lourdes Noronha Motta , Silva Gilbert
Published: September 2018

Stainless steel components produced by powder metallurgy constitute an important and growing segment of the industry. The high energy ball milling process can be an alternative for the recycling of the stainless steel chips. A major advantage of stainless steel is its ability to be recyclable. The reuse of recyclable materials has as main objectives to minimize the environmental impacts and to rationalize the use of the energy chains. This work aims at the production of stainless steel, starting from machining chips pure, and with the addition of vanadium carbides by high energy planetary milling with ball to powder weight ratio 20:1, and mill speed of 350 rpm milled in argon atmosphere for 50h. The compaction of stainless steel samples with vanadium carbide was made in a cylindrical matrix at a pressure of 700 Mpa. The sintering process was performed in a vacuum atmosphere furnace at a temperature of 1200 ° C for 1h. Through the milling process with the addition of carbide it was possible to produce stainless steel powder with a mean particle size of 49 μm. By X-ray diffraction was observed the appearance of the ferritic, austenitic phase and the martensitic phase induced by deformation phase that remained even after the sintering. The density of the sintered material is around 77% of the melt, and the obtained porosity was low.
Effect of Copper and Magnesium on the Microstructure of Centrifugally Cast Al-19%Si Alloys
Authors: Contatori Chester , Couto Antônio Augusto , Vatavuk Jan , Borges Arnaldo A. Ciquielo , de Lima Nelson Batista , Baldan Renato
Published: September 2018

Hypereutectic Al-Si alloys can be used in applications that require high wear resistance. Such wear resistance is achieved by the presence of hard primary silicon particles, allied to the formation of Mg2Si intermetallic phase when magnesium is added in this alloy. Centrifugal casting generates a gradient in the microstructure of hypereutectic Al-Si alloys that can favor such applications. Cylindrical components of Al-19%Si alloy containing added copper and magnesium contents were processed by centrifugal casting. The purpose of this study is to investigate the formation and segregation of particles of primary silicon (β) and Mg2Si in Al-19%Si alloy containing additions of copper and magnesium. Because the density of silicon (2.33 g/cm3) and Mg2Si (1.88 g/cm3) is lower than that of aluminum (2.67 g/cm3), centrifugal casting causes primary silicon (β) and Mg2Si particles to concentrate more at the outer wall of the centrifuged pipe. In this study, primary silicon (β) and Mg2Si particles were found to be retained at the outer wall of the pipe. It is believed that the rapid cooling of the molten metal in the region of contact with the mold, whose temperature is lower than that of the molten metal, allied to the centrifugal force, prevented the particles from migrating to the inner wall of the pipe. The microstructure shows a gradient in the distribution of these phases, enabling the production of a functionally graded material. The addition of copper and magnesium leads to the formation of Mg2Si and Al5Cu2Mg8Si6 phases, reducing the amount of primary β phase (Si) particles. In all the evaluated conditions, a tendency is also observed for a gradual increase in the segregation of silicon towards the inner wall along the entire length of the centrifuged pipe.
Corrosion Characterization of AISI 304 Stainless Steel Filter
Authors: Barbosa Lusinete Pereira , Correa Olandir Vercino , Filho N. Karsokas , Costa Isolda
Published: September 2018

Pre-sintering for removal of lubricants is one of the most important steps in processing of powder metallurgy materials to achieve corrosion resistance. This is often the most neglected step in the sintering process. Incomplete removal of these organic compounds may result in sensitization of sintered parts. The aim of this study is to investigate the effect of lubricant removal process on the corrosion resistance of sintered AISI 304 L stainless steel filters. Pre-sintering was carried out at 450° C and sintering at 1150° C. As lubricant, 1% wax was used. The corrosion resistance of sintered samples was evaluated by polarization and tests, optical and scanning electron microscopy. The results showed that lubricant removal was not complete and during sintering sensitization of the stainless steel occurred decreasing the localized corrosion resistance of the stainless steel.
Development of a Microtorquemeter for the Evaluation of the Implant Abutment Interface Behavior
Authors: Aranha L.C. , Mucsi Cristiano Stefano , Ceoni F.C. , Alencar M.C. , Rossi Jesualdo Luiz
Published: September 2018

This paper presents the initial developments of a prototype device intended to perform measurements of the fastening torque in the range bellow 1 N.m – hereby denominated microtorque. The device is intended to yield data for analysis of in vitro torquing and detorquing experiments, for fixation and removing of abutments in dental implants and implants in artificial bones. The analysis of the data acquired allowed the authors to observe characteristic fingerprints or signal signatures associated to the type of abutment or implant under experimentation as well as of the mechanical prototype characteristics. In this paper, two different systems of abutment and implant were analyzed. The correlation between the phenomena associated to the signal fingerprints indicate that the developed measurement protocol may be extended to other implant / abutment systems. The authors suggest that the insertion and removal torque curves evaluated in this study would facilitated the correlation between the abutments stability in actual patients and the dynamical behavior under masticatory function.
Comparative Analysis of the Influence of 10 and 5% Hydrofluoric Acid Etching on the Average Roughness of Lithium Disilicate Used in Dental Prostheses
Authors: Baumgardt Guilherme Ribeiro , Maffra Ana Carolina Motta , de Sousa Bernardo Tomas José Dias , de Carvalho Cristiane Fonseca , de Melo-Silva Cláudio Luis , de Melo-Silva Tereza Cristina Favieri , Lins Jefferson Fabricio Cardoso
Published: September 2018

The objective of this study was to analyse the variation of the average roughness (Ra) of a dental ceramic based on lithium disilicate after the etching of the surface with hydrofluoric acid (HF) in different concentrations in relation to the bond strength of this ceramic to the resin cement. The vitroceramic samples were divided into three groups: G1 (control, without etching), G2 (etching with HF 5%) and G3 (etching with HF 10%). The samples were exposed to the HF for 20 seconds at both concentrations. The average surface roughness after etching was analysed using the Confocal Zeiss Axio CSM 700 microscope and after the cementation and photoactivation of the resin cement the samples were submitted to a micro-shear test. The morphological analysis showed that the etching promoted the dissolution of the vitreous component and exposed the crystals of the ceramic for both concentrations, increasing the Ra values in relation to the control group (G1 = 0.331 ± 0.012 μm, G2 = 0.742 ± 0.126 μm; G3 = 1.335 ± 0.217 μm), with G3 having the highest Ra value. The highest values of bond strength were obtained by G3, with G1 = 17 ± 1.38 MPa, G2 = 24 ± 1.47 MPa and G3 = 30 ± 2.83 MPa. It can be concluded that the increase of the Ra by the HF etching promoted an increase of the bond strength between the lithium disilicate and the resin cement. However, the most effective superficial etching was with 10% HF.
Characterization of Galvanic Sludges Waste Derived of the Metal Plating Industry from Cariri Region, Northeastern of Brazil
Authors: de Oliveira Cícero Lucas Martins , de Paula Filho Francisco José , Moura João Victor Barbosa , Freitas Daniel Muller G. , Santiago Marcelo Oliveira
Published: September 2018

In this study, galvanic sludge waste (GSW) was characterized in order to identify its chemical and structural properties, allowing indicate reuse, treatment and final disposal methods, and evaluate the environmental hazards. The characterization of the galvanic sludge sample originating from a surface treatment plant from galvanic industries of semi-jewels in the Cariri region, NE of Brazil was performed. The chemical characterization of the samples by flame atomic absorption spectroscopy (FAAS) and X-Ray Fluorescence (XRF) showed that Zn and Cu are the predominant elements. However, elements like Ni, Cd, Mn, Fe, Cr and Co are present as a minority or as trace constituents. The concentrations of residues were higher, except Ni, in the LM industry (27 g Zn.kg -1, 194 g Cu.kg -1, 8 g Fe.kg-1, 538 mg Cd.kg -1, 227 mg Ni.kg -1, 73.5 mg Cr.kg1, 14 mg Co.kg-1) in relation to LJ (11 g Zn.kg-1, 3 g Fe.kg-1, 102 g Cu.kg-1, 2 g Cd.kg-1, 141 mg Ni.kg-1, 11 mg Co.kg-1), denoting that there is no uniform standard in the treatment process of the effluent from baths for Metal deposition. According to the standard procedure (Brazilian norm NBR10004/04) the elements Cd and Cr are the main constituents responsible for the classification of the residues as hazardous. The X-ray diffractogram of the dried galvanic sludge only revealed the presence of BaSO4 and CuO as crystalline phases, a result which agrees with the results from FT-IR. The results point to an attractive way of valorizing GSW avoiding the negative impact associated with its disposal in landfills.