bluuebunny/crossref_metadata_2025 huggingface dataset:
Iron Ore Tailing as Addition to Partial Replacement of Portland Cement
Authors: de Magalhães Luciano Fernandes , de Souza Morais Isabella , dos Santos Lara Luis Felipe , de Resende Domingos Sávio , Menezes Raquel Maria Rocha Oliveira , Aguilar Maria Teresa Paulino , da Silva Bezerra Augusto Cesar
Published: September 2018

The manufacture of Portland cement used in the production of concrete emits large amounts of CO2into the atmosphere, contributing to the increase of the greenhouse effect. The environmental impact generated by the mineral exploration activity is a problem of easy verification, especially in open pit mines. The present work evaluated the possibility of using iron ore tailing as an addition to the partial replacement of the cement in mortars. The iron ore tailings were processed by drying in oven (48h at 105oC) and milling in a planetary mill (10min at 300RPM), obtaining medium grain size of 14,13 μm. For the characterization, laser granulometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal and thermogravimetric analysis (DTA / TGA) were performed. The sample is composed predominantly by quartz, hematite, goethite and gibbsite. After the characterization, the waste was used in the preparation of test specimens, with 10, 20 and 30% weight substitution of the cement. The composites were submitted to compression tests, with ages of 3, 7 and 28 days, using a strength rate of 0,25MPa/s. The mortars with 10, 20 and 30% of substitution presented resistance of 41.65, 36.26 and 31.64 MPa, being able to be characterized as category of Portland cement of resistance 40, 32 and 25 respectively. Considering the reduction of cement in the mortars produced, the results of compressive strength were relevant for the substitutions. The cements produced with the substitutions according to the Brazilian standards under the mechanical aspect can be classified as Portland cement.
Sericitic Phyllite as Addition in Portland Cement
Authors: de Souza Morais Isabella , de Magalhães Luciano Fernandes , dos Santos Lara Luis Felipe , Siqueira Corrêa Elaine Carballo , Menezes Raquel Maria Rocha Oliveira , de Aguilar Maria Teresa Paulino , da Silva Bezerra Augusto Cesar
Published: September 2018

Pozzolans are materials that when milled are able to react with the cement, forming compounds with binder properties. Seeking to reduce costs and improve Portland cement performance, the cement industry has used mineral additions such as pozzolans, partially replacing clinker in Portland cement. Sericitic Phyllite is a metamorphic rock, considered sterile by iron mining. It is extracted from the pit to enable the extraction of iron ore and is disposed in sterile piles, representing an environmental liability. The present work evaluated the possibility of the Sericitic Phyllite acquires pozzolanic properties from thermal treatment, to be used as mineral addition in the partial substitution of Portland cement in mortars. The material was processed by milling in its natural moisture of 8% using a high performance planetary mill, and calcination in an electric resistance furnace at different temperatures (350, 550 and 850oC) for thirty minutes each. It was characterized by laser granulometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential thermal and thermogravimetric analysis (DTA/TGA). After characterization, specimens were prepared with 25% substitution by weight of the Portland cement by the Sericitic Phyllite. The calcined material in 350, 550 and 850oC reached, respectively, 70%, 76% and 82% of the resistance of the control mortar. The results indicate the feasibility of using the Sericitic Phyllite as mineral addition in Portland cements as the mortars with the calcined material in all temperatures reached 32MPa.
Preparation and Compressive Strength Evaluation of Concrete Containing Oil Sludge as Additive
Authors: Araujo Antonio S. , Coriolano Ana C.F. , Bandeira Rafaely A.F. , Delgado Regina C.O.B.
Published: September 2018

Concretes were prepared containing oil sludge additive to produce new materials for construction. The oil sludge and concrete have previously been characterized in terms of chemical composition of the elements present in the materials. The concrete blocks were produced with a defined amount of oily sludge of 3.0 mass% on cement/water factor. All samples were cured at room temperature and then heated at 200 °C for 3 hours and 292 °C for 2h. The surfaces of the samples were subjected to previously grinding for the compressive strength testing. These tests were conducted in a press of 2000 kN load capacity. It was found that concrete containing additive showed a positive response in all the compressive strength tests, compared to concrete without the additive
Influence of Glass Residue Addition on the Properties of Adhesive Mortar
Authors: dos Santos Diogo Pereira , Garcez de Azevedo Afonso Rangel , Alexandre Jonas , Dias Dylmar Penteado , de Castro Xavier Gustavo , Garcia Filho Fabio da Costa , Monteiro Sergio Neves
Published: September 2018

The use of glass residue as a finely ground mineral additive, in partial replacement of cement and aggregates, is a promising direction for recycling. This work aimed to analyze the influence of residues from the glass cutting process on adhesive mortar, as partial replacement of cement and small aggregates. The powdered glass was used in amounts of 10, 15 and 20 wt% in substitution for Portland cement and, in another moment, in substitution for small aggregates. It was verified that the substitution enhances the adhesion resistance of the mortar with increasing curing temperature.
Physical Properties of PHB/VMF2 Nanocomposite Microcapsules in Water
Authors: de Carvalho Arjona Jéssica , Valenzuela-Díaz Francisco Rolando , Wiebeck Hélio , Hui Wang Shu , da Silva-Valenzuela Maria das Graças
Published: September 2018

The characterization of nanocomposites microcapsules made of biodegradable polymers is really important to science and technology, as different systems can be produced targeting unique properties. The aim of this study is to prepare and to evaluate oil loaded PHB/VMF2 microcapsules’ behavior in water. The microcapsules were analyzed by FTIR, SEM and XRD. The biodegradable nanocomposite present exfoliated clay (XRD) whose absorption at 989 cm-1(FTIR) indicates the Si-O stretching vibration, from VMF2. The microcapsules observed by SEM presented spherical shapes and some average diameters from 12 μm to 35 μm, depending on the composition of the shell and the presence or absence of the encapsulated oil. Compared to microcapsules’ shell made from PHB, those from the nanocomposite PHB/VMF2 proved to display better mechanical resistance thus very few fractured particles were observed by SEM.
Comparative Analysis of the Tensile Properties of Polyester and Epoxy Composites Reinforced with Hemp Fibers
Authors: Rohen Lazaro Araújo , Neves Anna Carolina Cerqueira , dos Santos Jheison Lopes , Nascimento Lucio Fabio Cassiano , Monteiro Sergio Neves , de Assis Foluke Salgado , Simonassi Noan Tonini , da Silva Luis Carlos
Published: September 2018

The present work compares the tensile properties of polyester and epoxy matrix composites reinforced with hemp fibers. Polyester and epoxy reinforced with different volume fractions of hemp fibers up to 30% were prepared according to ASTM D-638-14 and tensile tested. The epoxy matrix composites reinforced with 30% of fibers presented tensile strength of 53 MPa, while those of polyester matrix, 25 MPa. The elastic modulus of the epoxy matrix composites was 1.75 GPa and that of the polyester matrix 4.05 GPa. The tests showed that the resistance of the epoxy composites reinforced with hemp fiber is superior to those of polyester matrix. However, the stiffness of the polyester/hemp fiber composites is higher than the epoxy/hemp fiber ones.
Antimicrobial Activity of PET-Silver Nanocomposite Filaments
Authors: Guerra Marcos Antônio , Swerts Jeferson Prado , Funcia Mei Abe , Campos Maria Gabriela Nogueira
Published: September 2018

This study evaluated the antimicrobial activity of PET-Silver nanocomposite filaments at different concentrations (0, 0.180%, 0.135%, 0.090%, 0.045% and 0.022% w/w) of silver nanoparticles in order to determine the minimum inhibitory concentration and minimum bactericidal concentration of silver incorporated in the PET matrix. The in vitro antibacterial activity was evaluated by the AATCC standard 100: 2012 method, against Staphylococcus aureus ATCC 6538, and Klebsiella pneumonia ATCC 4532. The filaments were tested after one and twenty-one months of preparation to evaluate the effect of time on the antimicrobial activity of the nanocomposites. Moreover, the antimicrobial activity was also evaluated after dyeing the filaments. The silver-free PET filaments have not demonstrated antimicrobial activity and cytotoxicity against human dermal fibroblasts. Nevertheless, excepted for the filament with 0.022% of silver nanoparticles, all PET-Silver nanocomposites reduced more than 99% the colony-forming units (CFU) of Staphylococcus aureus and Klebsiella pneumonia after one and twenty-one months of preparation. This suggests that the MIC of silver nanoparticles incorporated in the PET matrix is lower than 220 ppm (w/w) and the MBC is between 0.022 and 0.045% (w/w). However, after the dyeing process, no antimicrobial activity was observed for any PET-Silver nanocomposite filaments. This may be attributed to the release of silver from the PET matrix during the dyeing process or to the reaction/inactivation of the silver ions by the salts used in this chemical treatment.
Analysis of the Influence of Injection Process Parameters of Polymer Blends from Printers
Authors: Schneider Eduardo Luís , Gonçalves José Victor Rebechi Valle , Adam Ana Paula , de Quevedo Daniela Muller , Robinson Luiz Carlos , Otterbach João Claudio Hennig , de Aquim Patrice Monteiro
Published: September 2018

Among the 40 million tons/year of e-waste discarded in the world, the recycling of polymers depends on the correct separation in disassembly as well as control of fluidity during processing. The objective of this study is to analyze the feasibility of HIPS blends recycling with other main polymers present in printers, through the analysis of the influence of pressure and speed parameters of injection to subsequently perform tensile tests for mechanical characterization. For this purpose, post-consumption polymers from disassembled printers were separated for analysis and comparison of HIPS-90%/PS-10% blend with HIPS-100%, which were injected into a mold with geometry of test specimens for tensile test, complying with ASTM standard D638-14, employing variations in pressure and speed and maintaining constant temperature. To identify the influence of levels of pressure between 45 and 60 bar and speed between 45 and 60 mm/min in yield point and elongation of the material a two-way ANOVA without replication was applied. When comparing the different levels of pressure and speed considered and evaluated in relation to the material composition, there were no significant differences between the levels, for both yield strength and for elongation. It was verified a variation on the mechanical properties of the PSHI and PS blend in relation to the pure PSHI, probably due to the amount of brominated flame retardants and elastomers present in PSHI from printers.
Degradation of Colored Polystyrene Films
Authors: de Araújo Francisca Pereira , Osajima Josy Anteveli , de Araujo Mônica Regina Silva , da Silva Filho Edson Cavalcanti , de Souza João Sammy Nery
Published: September 2018

Polystyrene is commercial polymer of extensive use in industrial scale due to great physical and chemical properties and low cost. Lifespan of polymer materials can be changed by incorporation of additions to polymeric matrix.The present study aimed to evaluate the influence of crystal violet dye in polystyrene matrices when irradiated by visible radiation. The samples were studied in the form of films, in which solution of crystal violet (5.0x10-4mol.L-1) was added to the PS solution (8% w / w). The films were irradiated with commercial lamp for 150 hours and analyzed with UV-Vis and FTIR. The results showed that the dye degraded at a rate of 16%, however the FTIR analysis revealed that polystyrene did not degrade under the conditions studied, since no formation of carbonyl compounds was observed.
Biocomposite of Ultra-High Molecular Weight Polyethylene and Hydroxyapatite with Antibacterial Properties by the Incorporation of Zinc Oxide Nanoparticles
Authors: Galli R. , Soares M. , Domingos L.P. , Batiston E.B. , Silva Luciano Luiz , Mello Josiane Maria Muneron , Duarte G.W. , Riella Humberto Gracher , Fiori Márcio Antônio
Published: September 2018

With the increasing demand of biomaterials, numerous studies have been developed seeking to improve its properties through new obtaining and manufacturing processes. This work aimed to aggregate antimicrobial property to a biocomposite constituted of a matrix of ultra-high molecular weight polyethylene (UHMWPEE) and hydroxyapatite, by the incorporation of zinc oxide nanoparticles. The samples were prepared based on a standard composition containing 95.0 wt% of UHMWPEE and 5.0 wt% of hydroxyapatite (blank). Three compositions were evaluated ranging the amount of zinc oxide nanoparticles incorporated in the standard sample. It was observed that the increase of zinc oxide concentration aggregate a good antibacterial property in the samples tested without cause significant changes in the mechanical properties of the composites.
Influence of the Geometric Characteristics of the Mini-Implants on Mechanicals Properties Using Artificial Bone Similar to Anterior, Middle and Posterior Regions of the Jaws
Authors: Pesqueira E.I.O. , Mucsi Cristiano Stefano , Rossi Jesualdo Luiz
Published: September 2018

The objective of this study was to identify the best torque of insertion and removal of mini-implants with a twin screw design (compact and self-drilling) into artificial bones with density and trabecular thickness, similar to anterior, middle and posterior regions of the jaws. Observation of the mini-implants surface using electron microscopy was performed before and after the tests. The torque values obtained during the insertion and removal was measured by digital torque wrench. The analyzed results led to the conclusion that the insertion and removal torques were larger with increase in bone density and cortical thickness. The design of the threads of the mini-implants influenced the insertion torque. Threads with smaller pitch increased the value of insertion torque. The anterior bone drilling installation reduces the insertion torque independent of bone density. Torque increased mainly by increasing the bone density and not necessarily with increased cortical thickness suggesting that the bone density of the trabecular bone must be considered in designing the installation of mini-implants.
Active Packaging Using Orange Oil Incorporated into PBAT Biodegradable Films
Authors: de Andrade Michelle Félix , da Silva Gois Gelsoneide , da Silva Garcia Sônia Maria , da Silva Ivo Diego Lima , Caetano Viviane Fonseca , de Almeida Yêda Medeiros Bastos , de Melo Tomás Jeferson Alves , Vinhas Glória Maria
Published: September 2018

The use of essential oils as additives to biodegradable polymers has been widely investigated for application in active packaging with a focus on food preservation. The purpose of this article is to observe the changes caused by orange oil in different concentrations (5, 10 and 15 %), when incorporated into thin PBAT films. The results showed that the rheological behavior of PBAT did not change with the addition of 5% oil, the torque remained constant. The oil did not significantly alter the Tm of all the films, remained close to pure PBAT (117.91 °C), but an addition of 5% oil increased Tc of approximately 2.6 °C (4%). TGA maintained degradation temperature for the samples with initial degradation temperature (T0) of approximately 388 °C and maximum degradation temperature of 429.25 °C. Stress at break, Elastic modulus and Specific deformation decreased with increasing oil content. Given this, we concluded that the oil does not alter the thermal properties of PBAT observed in TGA, but making it more flexible and fragile by acting as a plasticizer in the PBAT structure.
Micromechanical Modeling of DP600 and DP800 Steels Plastic Behavior Based on the Mori-Tanaka Homogenization Method
Authors: Barbosa Gustavo Coqui , Moreira Luciano Pessanha , da Silveira Lílian Barros , Cardoso Marcelo Costa
Published: September 2018

The properties of the dual-phase steels are attributed to the chemical composition, type, size, amount, and spatial distribution of different phases that can be obtained during thermomechanical treatments. In this way, modeling of the mechanical behavior of the dual-phase steel constituents, namely, ferrite and martensite, is crucial to the numerical simulation of sheet metal forming processes mainly to forecast the residual stresses per phase. In this work, the microstructure of as-received DP600 and DP800 cold rolled steel sheets with 1.2 mm nominal thickness were firstly characterized by means of scanning electron microscopy technique. The grain sizes and volume fractions of ferrite and martensite phases were obtained by means of digital image analysis. The Mori-Tanaka homogenization scheme was implemented in the finite element code ABAQUS assuming linear isotropic elasticity and isotropic work-hardening behavior for both ferrite (matrix) and martensite (inclusion) phases. The numerical predictions obtained with the Mori-Tanaka homogenization scheme for the macroscopic uniaxial tensile behavior are in good agreement with the experimental curves of both dual-phase steels.
Effect of Controlled Cooling after Hot Rolling on the Mechanical Properties of a Low Carbon Niobium Microalloyed Steel Wire Rod
Authors: David Felipe Farage , David Sayd Farage , Rocha Renan Carreiro , Ferreira Ricardo Arthur Sanguinetti
Published: September 2018

The wire rod has high relevance due to its wide application as a raw material for steel wire and wire processed in cold rolling mills and drawing. The control of process variables, such as cooling rate, coiling temperature, rolling speed is essential for obtaining the microstructures and therefore mechanical properties of the material. The purpose of this work is to study the behavior of the microstructure and mechanical properties with the variation of thermomechanical treatment in the hot rolling of wire rod. The steels used in this study were the microalloyed niobium steel equivalent to ASTM A913 grade 50 and carbon steel equivalent to ASTM A510 grade 1013. Despite the carbon steel has higher equivalent carbon to microalloyed steel, was found higher yield strength (σe) in the microalloyed niobium steel. Thus, by applying appropriate thermomechanical treatment in microalloyed steel is possible to improve mechanical properties mainly due to grain refining.
Evaluation of the Bactericidal Properties of the Biomimetic Coating of Ha Doped with AgNO3
Authors: de Sousa Lucíola Lucena , Prado Deborah Gouvêa , Coelho Mariny Fabiéle Cabral , Ricci Virgilio Pereira , Ferreira Guilherme Vilela , da S. Rigo Eliana C. , dos Santos Fernandes Mérilin Cristina , Mariano Neide Aparecida
Published: September 2018

Commercially pure titanium and its alloys have been widely applied as implant materials with excellent long-term results and present benefits compared to other metal biomaterials because of the good mechanical strength and modulus of elasticity with values close to those of the bone. Titanium implants coated with hydroxyapatite give the metal a bioactive surface, which induces a direct connection between the implant and the bone tissue. As a consequence, the time for osseointegration, and hence the total treatment time, may be reduced. This paper aimed at studying the bactericidal effect of silver nitrate at 10 ppm and 100 ppm, incorporated in the layer on the surface of commercial titanium. The results showed efficiency in both osseointegration and bactericidal effect, confirmed by scanning electron microscopy, X-ray diffraction and corrosion tests. The bacterial culture tests, by means of the halo inhibition tests, indicate that the doping with AgNO3in concentrations 10 and 100 ppm did not present significant variation.
Proppants Development and the Shale Oil and Gas Market Perspective
Authors: de Campos Vitor Polezi Pesce , Amaral Labat Gisele Aparecida , Gouvea Douglas , Lenz e Silva Guilherme Frederico Bernardo
Published: September 2018

Unconventional shale gas reservoirs have driven the growth of the oil and gas market to a new reality: till 2035 a 26% increase in US fuel production is predicted. Thus, the hydraulic fracturing technique has been increasingly used as a resource for shale gas extraction and the consequent use of proppants. Several studies have now evaluated the use of nanostructures to produce special proppants, such as nanosensors, coatings, membranes and special fluids. This work presents the perspective of the market for oil, gas, shale, hydraulic fracturing and proppants in addition to a current development of proppants. Proppants were characterized through API RP 19C, DTA and DRX analysis. The morphology of carbon nanostructures (carbon nanotubes, carbon black and few layers’ graphite from reduced graphene oxide synthesis) produced and introduced on AM (alkali-activated metakaolin) matrix composites were evaluated using scanning transmission electron microscopy (STEM).
Influence of GPTMS Precursor Concentration as Pretreatment of Galvanized Steel
Authors: de Oliveira Henrique Carvalho , de Almeida Neuwald Oscar , Beltrami Lilian Vanessa Rossa , Gerhardt Gunther Johannes Lewczuk , Kunst Sandra Raquel
Published: September 2018

This work aims to evaluate the influence of the alkoxy precursor concentration on the morphological and electrochemical characteristics of the chemical conversion layer formed on a galvanized steel surface. Different films were obtained by the dip coating method varying precursor concentrations in 2, 5 and 10%. According to the SEM and EIS results the corrosion resistance property increases for higher GPTMS precursor concentrations.
Influence of Thickness on Magnetic and Microstructural Properties in Electrical Steels Semi-Processed of Low Efficiency
Authors: Trindade M.A. , de Campos Marcos Flavio , Landgraf Fernando José Gomes , de Lima Nelson Batista , Almeida A.
Published: September 2018

In this study, a steel for semiprocessed electrical purposes of non-oriented grain with approximately 0.05% carbon content and 0.02% silicon content was evaluated. Lamellas with kind of thicknesses 0.58 mm, 0,66 mm and 0.87 mm were processed on an industrial scale with a strain rate in the hardening lamination between 3 and 5%. The magnetic properties were evaluated after the wet heat treatment. The loss separation method was applied, estimating the hysteretic plot with hysteresis measure in the quasi static condition and the parasitic losses calculated according to Thomson's Equation. By increasing grain size, permeability increases and coercivity decreases. However, in the case of losses, there is an optimum grain size. After the procedure of separation of losses, it was observed that increase of thickness results in increase of the anomalous parcel of magnetic losses.
Ellipsometric Characterization of AZ31 Magnesium Alloy
Authors: da Silva Almeida Darlene Souza , da Silva Ladario , Garcia Marcela Teixeira Dalboni , de Castro José Adilson , Moreira Luciano Pessanha
Published: September 2018

Ellipsometry is a non-destructive and indirect technique able to characterize both optical and dielectric properties of thin films and bulks, besides determining the thickness of thin films. This characterization is performed by evaluating the change in the polarization state of the incident light when it interacts with the material of interest. In this work, the ellipsometry technique was used to characterize optical properties of AZ31 magnesium alloy samples. This alloy has several interesting properties such as low density, high thermal conductivity, good machinability, among others, which makes it suitable for use in automotive and aerospace components. However, when this alloy is exposed to ambient atmosphere, it undergoes natural oxidation, developing a surface film of oxides and/or hydroxides. This study aimed to establish an efficient methodology for accessing the optical and dielectric characteristics of the substrate (AZ31 alloy) as well as those for the surface film of oxide/hydroxides, and to obtain the thickness of this film. Four samples mechanically grinded and polished were investigated: One sample, namely P sample, was subjected to the ellipsometric measurements immediately after grinding and polishing and three samples, namely A10, A50 and A60, were exposed to the air at 150°C during 10, 50 e 60 minutes, respectively. From the results of the ellipsometric measurements for P sample, it was possible to determine the refractive index (n) and extinction coefficient (k) curves as a function of the wavelength (λ) for the substrate (AZ31 alloy). Besides, through appropriate modeling, it was possible to determine the thicknesses of the oxides/hydroxides films presented in A10, A50 and A60 samples. The thicknesses values obtained seem to be quite coherent when we analyze the surface roughness of these samples using the confocal microscope, validating the optical model constructed to represent the A10, A50 and A60 samples. The results achieved in this study can contribute to the study of both of oxides/hydroxides layers growth and protective coating films growth for AZ31 magnesium alloy.
Evaluation of Microstructural Phenomena in the Utilization of Porcelain Tile’s Shards to Obtain New Ceramic Materials
Authors: Gripa Everton M. , Gonçalves I.L.M. , Almeida Valeria
Published: September 2018

The industry of ceramic tiles exploits large amounts of natural resources and produces a lot of solid waste, especially porcelain tiles, a product of this industry that involves high technology fabrication. A previous study showed that, if the calcination conditions are respected (1200°C for 2 hours), it is possible to produce new ceramic tiles from the shards of porcelain tiles generated during construction or demolition. This study uses techniques such as X-Ray Fluorescence, X-Ray Diffraction and Scanning Electronic Microscopy in order to investigate the microstructural phenomena that allow the new materials’ sintering.
Kinetics Modelling of the Adsorption Process of Zinc Ions by Glass Microparticles
Authors: Mendes Elton , Angioletto Elidio , Mendes Erlon , Ternus Raquel , Betiatto Kelly Regina , Heloisa Riss , Testa Karine , Piletti Raquel , Riella Humberto Gracher , Fiori Márcio Antônio
Published: September 2018

The oligodynamic property is a lethal effect which some atoms exert over bacteria, fungi and other microorganisms. The oligodynamic property can be promoted by glass microparticles doped by zinc ionic specimens utilizing the ionic exchange processes. This study is aimed at modelling the behavior of adsorption mechanisms of the zinc ions on glass microparticles absorbent, with potential use as antimicrobial material. Aqueous solutions of zinc nitrate were used as the ionic supplying of zinc ions. The amount of zinc adsorbed on the glass was determined by spectroscopy of atomic absorption and with a mass balance analysis for each adsorption conditions. The experimental data were modeled by three Eq.s employed in adsorption kinetics studies: pseudo first order, pseudo second order and Elovich Eq.. The pseudo second order data model presented the better adjust condition. A sample of zinc glass microparticles, prepared at the finest conditions established by the kinetic model of pseudo second order, was submitted to microbiological analysis: agar diffusion test with Pseudomonas aeruginosa and Staphylococcus aureus and with Candida albicans. The glass doped with ionic zinc inhibited the growth of microorganisms in every conducted analysis.
Assessment of the Photocatalytic Efficiency of TiO2 in the Presence of Sulphate
Authors: Pinto Lucas Italo Freitas , de Sousa Sá Alexandro , dos Santos Valdeci Bosco , Filho Edson Cavalcanti Silva , Osajima Josy Anteveli
Published: September 2018

The use of salts on the degradation of toxic substances may cause the acceleration or delay of radicals production originating from the degradation process. This work had as its objective to investigate the presence and absence of potassium sulphate salt on the photocatalysis of Bentazone using TiO2 as a catalyzer. The effect of the sulphate ion on the photodegradation of the Bentazone herbicide was studied using concentrations of 0,05; 0,10 and 0,20 g L-1 with 0,5 g L-1 of TiO2, in suspension of 180 mL from bentazone solution (3,0x10-5 mol L-1). The samples were analyzed through UV-Vis spectroscopy. The presence of sulphate ions presented a difference of 3,3% on the degradation of bentazone in comparison to TiO2 alone.
Selective Copper Oxide Coating on Aluminum Panels for Solar Heating Absorption
Authors: Monteiro Sergio Neves , de Oliveira Braga Fabio , Tommasini Flavio James , Pereira Artur Camposo , da Silva Figueiredo Andre Ben Hur , Santos da Luz Fernanda
Published: September 2018

The efficiency of heating absorption of aluminum sheets coated with copper oxide, CuO, was evaluated in solar panels. Coatings were produced by means of two techniques: vacuum metallic deposition and copper nitrate vaporization onto a pre-heated aluminum sheet. The optical and thermal efficiency of the coatings were evaluated through measurements of the spectral reflectance and surface temperature. The nature of the coating layer was investigated by macro examination. It was found that vacuum deposition presented superior optical efficiency and better adherence. By contrast, coatings produced from vapor are more uniform with higher concentration of CuO.
Effect of Hydrogen Decrepitation Pressure on the Particle Size of Rare Earth Based Alloys for Ni-Mh Battery Production
Authors: Soares Edson Pereira , Casini Julio Cesar Serafim , Vieira Ligia Silverio , Silva Franks Martins , de Faria Rubens Nunes , Takiishi Hidetoshi
Published: September 2018

This paper presents the results obtained from the hydrogenation and decrepitation of three LaNi-based alloys, La0.7Mg0.3Al0.3Mn0.4Co0.5Ni3.8, La0.7Mg0.3Al0.3Mn0.4Cu0.5Ni3.8and La0.7Mg0.3Al0.3Mn0.4Sn0.5Ni3.8, in the as-cast condition. The procedure for decrepitating the alloys to be used in the negative electrode of the batteries was carried out using a combination of various hydrogen pressures (2-9 bar) at room temperature. At 2 bar of H2it was revealed that Co, Cu and Sn have influence on the microstructures of the hydrogenated alloys and on the efficiency of hydrogen decrepitation. None of these alloys required thermal heating to activate and start the hydrogen absorption process. The decrepitated materials were characterized by scanning electron microscopy (SEM). The electrochemical measurements were performed using the tested negative electrode between two Ni (OH)2electrodes as a battery cell.
Neutrophil Vaccination Dynamics and Their Capacity To Mediate B Cell Help in Rhesus Macaques
Authors: Musich Thomas , Rahman Mohammad Arif , Mohanram Venkatramanan , Miller-Novak Leia , Demberg Thorsten , Venzon David J. , Felber Barbara K. , Franchini Genoveffa , Pavlakis George N. , Robert-Guroff Marjorie
Published: September 2018

Neutrophils are the most abundant leukocyte and play a critical role in the initial response to an Ag. Recently, their ability to contribute to adaptive immunity has been highlighted. We evaluated the ability of neutrophils from blood to contribute to the adaptive immune response in a preclinical rhesus macaque SIV vaccine trial. Replication-competent adenovirus-SIV recombinants induced neutrophil activation, B cell help markers, and enhanced ability to generate reactive oxygen species. Boosting with SIV vaccines (adjuvant together with ALVAC or DNA plus envelope protein) elicited significant neutrophil responses. Serum cytokine and chemokine levels induced correlated with the frequency of neutrophil subsets expressing IL-21, myeloperoxidase, and CD64. Post–SIV infection, neutrophils exhibited dysfunction, both phenotypically and functionally. B cells from protected and infected macaques cocultured with autologous polymorphonuclear cells, consisting primarily of neutrophils, were activated, underwent class switching, and produced Abs. This B cell help was not aided by addition of IL-10 and was largely contact dependent. Numerous genes associated with inflammation, Ab production, and chemotaxis were upregulated in the cocultured B cells. We conclude that immune stimulation by vaccination or antigenic exposure imparts a greater ability of neutrophils to contribute to the adaptive immune response. Harnessing this granulocytic response has the potential to improve vaccine efficacy.
Observed Antibody Space: A Resource for Data Mining Next-Generation Sequencing of Antibody Repertoires
Authors: Kovaltsuk Aleksandr , Leem Jinwoo , Kelm Sebastian , Snowden James , Deane Charlotte M. , Krawczyk Konrad
Published: September 2018

Abs are immune system proteins that recognize noxious molecules for elimination. Their sequence diversity and binding versatility have made Abs the primary class of biopharmaceuticals. Recently, it has become possible to query their immense natural diversity using next-generation sequencing of Ig gene repertoires (Ig-seq). However, Ig-seq outputs are currently fragmented across repositories and tend to be presented as raw nucleotide reads, which means nontrivial effort is required to reuse the data for analysis. To address this issue, we have collected Ig-seq outputs from 55 studies, covering more than half a billion Ab sequences across diverse immune states, organisms (primarily human and mouse), and individuals. We have sorted, cleaned, annotated, translated, and numbered these sequences and make the data available via our Observed Antibody Space (OAS) resource at http://antibodymap.org. The data within OAS will be regularly updated with newly released Ig-seq datasets. We believe OAS will facilitate data mining of immune repertoires for improved understanding of the immune system and development of better biotherapeutics.
On the security properties of Russian standardized elliptic curves
Authors: Alekseev Evgeny Konstantinovich , Nikolaev Vasilii Dmitrievich , Smyshlyaev Stanislav Vitalevich
Published: September 2018

На протяжении последних двух десятилетий эллиптические кривые стали неотъемлемой частью различных криптографических примитивов и протоколов. В связи с этим особенно важно использовать эллиптические кривые, которые не ослабляют стойкость таких протоколов. В работе исследуется стойкость эллиптических кривых, определяемых российскими рекомендациями по стандартизации, относительно известных вычислительных задач в группе точек эллиптической кривой. В частности, показано, что атака, предложенная Пети, Костерсом и Мессингом, не применима к стандартизированным в Российской Федерации эллиптическим кривым. Описан процесс выработки указанных кривых, основанный на использовании криптографических функций хэширования и позволяющий гарантировать псевдослучайность получаемых значений.
Об использовании подобия подстановок при определении ключа в сетях Фейстеля
Authors: Dmukh Andrei Aleksandrovich
Published: September 2018

Для сетей Фейстеля с ключевой разверткой, представляющей собой последовательность подвекторов ключевого вектора, рассматривается метод определения ключа с использованием подобия подстановок. Изучаются условия, при которых этот метод эффективнее тотального опробования. Приведены примеры применения метода к различным сетям Фейстеля указанного типа. Обсуждаются условия на ключевую развертку в сетях Фейстеля, обеспечивающие практическую невозможность применения как методов Исобе и Динура-Данкельмана-Шамира, так и метода с использованием подобия подстановок.
О множестве образов $k$-кратной итерации равновероятного случайного отображения
Authors: Mironkin Vladimir Olegovich , Mikhailov Vladimir Gavrilovich
Published: September 2018

Изучаются свойства графа $k$-кратной итерации равновероятного случайного отображения $f\colon \{1,\ldots,n\}\to \{1,\ldots,n\}$. Получены рекуррентные формулы для вероятностей принадлежности вершины множеству $f^k(\{1,\ldots,n\})$ и множеству висячих вершин в графе отображения $f^k$.
Подстановочные гомоморфизмы алгоритмов блочного шифрования и ${\otimes _{\mathbf{W}}}$-марковость
Authors: Pogorelov Boris Aleksandrovich , Pudovkina Marina Aleksandrovna
Published: September 2018

Известно (Lai X., Massey J. L., Murphy S., 1991), что последовательность раундовых разностей в $\otimes$-марковских алгоритмах блочного шифрования с независимыми и равномерно распределенными раундовыми ключами, алфавитом текстов $X$, абелевой группой $(X, \otimes )$ наложения ключа является марковской цепью. В 2017 году авторы указали условия, при которых укрупнение разностей (описываемое разбиением ${\mathbf{W}}$) $ \otimes $-марковского алгоритма дает снова марковскую цепь. Алгоритмы с таким свойством названы ${ \otimes _{\mathbf{W}}}$-марковскими. В настоящей работе продолжается исследование свойств ${ \otimes_{\mathbf{W}}}$-марковских алгоритмов. Выясняется связь между существованием гомоморфизмов у алгоритмов блочного шифрования и ${ \otimes_{\mathbf{W}}}$-марковостью.
An Inquiry Into the Early Careers of Master Clinicians
Authors: Murthy Vivek K. , O'Brien Bridget , Dhaliwal Gurpreet
Published: September 2018

Background 

Residents and fellows often seek to emulate master clinician role models; however, the activities these expert clinical faculty pursued early in their careers are not known.

Objective 

We studied the early career clinical experiences and learning behaviors of peer-defined master academic clinicians.

Methods 

We performed a retrospective, qualitative interview study of 17 members of the University of California, San Francisco, Department of Medicine Council of Master Clinicians. Between March 1 and May 31, 2016, we interviewed participants using a semistructured interview guide surveying their early career clinical experiences and learning habits. Interviews were audio-recorded and transcribed. We used a general inductive approach to code transcripts and to identify consistent themes.

Results 

Of the 28 council members invited to participate, 17 (61%) responded and were interviewed. Participants included 12 men and 5 women, with an average of 27 years in clinical practice (range, 13–50 years). Six participants were general internists, and 11 were internal medicine subspecialists. Based on thematic analysis of interview transcripts, 4 themes of clinical development emerged: (1) consistent learning efforts; (2) rigorous skill development; (3) cultivating habits of mind; and (4) clinically rich environments.

Conclusions 

Our study describes the early career experiences and learning behaviors of master clinicians. We aggregated key dimensions of the findings into a guide for residents, fellows, and junior clinicians interested in the pursuit of clinical excellence.
Training Toward a Movement: Career Development Insights From the First 7 Years of a Global Health Equity Residency
Authors: Palazuelos Daniel , Dhillon Ranu , Nelson Adrianne Katrina , Savage Kevin P. , Conover Rosabelle , Katz Joel T. , Rhatigan Joseph J.
Published: September 2018

Background 

The Doris and Howard Hiatt Residency in Global Health Equity and Internal Medicine at Brigham and Women's Hospital provides global health training during residency, but little is known about its effect on participants' selection of a global health career.

Objective 

We assessed the perceptions of residency graduates from the first 7 classes to better understand the outcomes of this education program, and the challenges faced by participants.

Methods 

We interviewed 27 of 31 physicians (87%) who graduated from the program between 2003 and 2013 using a convergent mixed-methods design and a structured interview tool that included both open-ended and forced-choice questions. We independently coded and analyzed qualitative data using a case study design, and then wove together the qualitative and quantitative data at the interpretation phase using a parallel convergent mixed-methods design.

Results 

Entering a career focused on social justice was cited as the most common motivator for selecting to train in global health. Most respondents (83%, 20 of 24) reported they were able to achieve this goal despite structural barriers, such as lower salaries compared with peers, a lack of mentors in the field, poorly structured and undersupported career pathways at their institutions, and unique work-life challenges.

Conclusions 

A majority of graduates from 1 dedicated residency program in global health and internal medicine reported they were able to continue to engage in global health activities after graduation and, despite identified challenges, reported that they planned long-term careers in global health.
Using Future Employers' Expectations to Inform Global Health Fellowship Curricula
Authors: Brown Heather A. , Mulherin Patrick , Ferrara William C. , Humphrey Mark E. , Vera Alexander , Hall Jeffrey W.
Published: September 2018

Background 

Fellowships in global health are increasingly popular and seek to equip physicians with the skills necessary to be effective global health practitioners. Little objective guidance exists on which skills make graduates competitive applicants from the perspective of potential global health employers.

Objective 

We sought to provide objective evidence for the qualifications that make applicants competitive for global health positions by analyzing the listed qualifications for current job openings in large global health organizations.

Methods 

The websites of 48 global health employers were systematically searched for current job postings between May and August 2017. Jobs were included for analysis if a medical degree was listed among the primary degrees accepted, and the job was based primarily in a low- or middle-income country.

Results 

A total of 5849 employment opportunities were posted during the search period, and 81 (1.4%) of these met inclusion criteria. Twenty-two (27%) jobs required and 35 (43%) preferred a relevant master's degree. Few jobs requested a candidate with a PhD and none mentioned tropical medicine training as a requirement or preference. Twenty-three jobs (28%) required and 19 (23%) preferred candidates to speak another language. Most jobs (69%, 56 of 81) required more than 5 years of relevant experience. Only 11 (13%) jobs were primarily clinical positions.

Conclusions 

For physicians pursuing a career in global health, most publicly searchable jobs require substantial previous experience and involvement in global health activities beyond clinical practice. Master's degree and language skills are frequently requested candidate qualifications.
Some reflections on inflation targeting, monetary–fiscal policy interactions, and unconventional monetary policies
Authors: Gaffard Jean-Luc , Napoletano Mauro , Battiston Stefano
Published: September 2018

We revisit the theoretical underpinnings of the monetary policy consensus before the Great Recession. We highlight how they resulted from New Keynesian dynamic stochastic general equilibrium (DSGE) models that (i) neglected the actual process of coordination in markets, (ii) saw price rigidity as an obstacle to the correct functioning of markets, and (iii) overlooked the effects of finance on the determination of credit supply. Furthermore, we outline some elements of an alternative framework conceiving the output-inflation dynamics as the result of coordination efforts in markets that are constantly in disequilibrium. We discuss how such a disequilibrium perspective leads to opposite conclusions with respect to DSGE models about the role of price rigidity and of fiscal and monetary policy interactions, and about the process of endogenous money formation and credit supply. Finally, in such a perspective, quantitative easing policies may play a key role also in normal times as key determinants of the distribution of financial risk.
Unconventional monetary policy: between the past and future of monetary economics*
Authors: Guerini Mattia , Lamperti Francesco , Mazzocchetti Andrea
Published: September 2018

In this paper we discuss some of the monetary policy issues that have involved major central banks worldwide since the 2008 financial crisis, and which remain open. We provide an excursus of the unconventional monetary policies adopted by central banks in the last decade, focusing on the European Central Bank and the Federal Reserve, and we discuss the rationale and efficacy of some unconventional monetary instruments, of inflation targeting and of central-bank independence. We also provide a perspective on possible future developments of monetary policy. We argue that while unconventional monetary policy was useful, there is still ample space for improvement: in the recessions to come, unconventional monetary policy will need to be better coordinated with fiscal, micro- and macro-prudential policies to provide more inclusive results that might positively affect the real economy beyond the financial system.
ECB monetary expansions and euro area TARGET2 imbalances: a balance-of-payment-based decomposition
Authors: Minenna Marcello , Dosi Giovanni , Roventini Andrea
Published: September 2018

The recent financial literature seems to have reached a consensus about the influence of European Central Bank (ECB) unconventional monetary policies in explaining the multiple divergent trends of TARGET2 (T2) balances in the eurozone from 2010 and the ensuing segregation of risks in each national economy. According to the ECB, ‘mechanical’ effects in the accounting of government bonds explain the explosion of T2 balances. Divergence could therefore not be attributable to a ‘capital flight’ from peripheral economies towards northern Europe. Such an explanation does not seem to fit well with the analysed cases of Italy, Spain, and Germany. A decomposition of the T2 balances through the analysis of the financial accounts of the balance of payments shows indeed that the deterioration in the balances of Italy and Spain is mainly due to a shift of private-sector financial wealth from government securities to foreign assets (bonds, shares, and mutual funds). In the case of Germany, the abnormal growth of T2 balances is mainly attributed to the persistent influence of current-account surpluses reaching 6–8 percent of GDP and increasing due to the indirect effects of quantitative easing policies on the exchange rate between the euro and the other major international currencies.
Global instability and the development project: is the twenty-first century different?
Authors: Ghosh Jayati
Published: September 2018

Despite a few pockets of relatively fast expansion, overall deficiency of demand characterises the world economy. The external stimulus provided by the US is declining; Europe's net impact is negative because of the emphasis on generating current-account surpluses. While China is already a significant global economic player, it cannot adequately counter the effect of this reduced impetus from the major developed countries. Much of the developing world is relying on unsustainable debt-driven bubbles in the financially liberalised environment to generate economic recovery. Sustaining the development project will require countries to shift from export-oriented growth to more reliance on domestic demand through wage and employment increases.