bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Development of Compaction Tools for Powder Metallurgy
Authors: dos Santos Mauricio , Rodrigues Wilson C. , de Matos Dias Ana Paula S. , Schaeffer Lirio , de Matos Dias Arão
Published: July 2017

The aim of this work is to analyse options of different powder metallurgy tools design with upper punch adapted with springs and its benefits with regards green density of the parts compacted in hydraulic press. Crack of the parts also were observed.
Effect of Sn and Cu on Corrosion Resistance of LaMgAlMnCoNi Type Alloys
Authors: Casini Julio César Serafim , Saeki Margarida Juri , Guo Zai Ping , Liu Hua Kun , Faria R.N. , Takiishi H.
Published: July 2017

This paper reports the results of investigation carried out to evaluate the corrosion resistance of tin and copper in as-cast alloys represented by two sequential series, first: La0.7Mg0.3Al0.3Mn0.4Co0.5-xSnxNi3.8 (x = 0.0, 0.1, 0.2, 0.3 and 0.5) and second: La0.7Mg0.3Al0.3Mn0.4Sn0.5-yCuyNi3.8 (y = 0.0, 0.1, 0.2, 0.3 and 0.5). Electrochemical methods, specifically, polarization curves have been employed in this study. Copper substitution yielded good overall performance of the alloys.
Kinetic Behavior of Self-Reducing Pellets Containing Coal of Elephant Grass
Authors: da Rocha Elisa Pinto , Hosken Camila Martins , da Cunha Rocha Adriana , da Rocha Santos Andrea Pedroza , de Castro Jose Adilson
Published: July 2017

Aiming to reducing the gas emissions in the steel mill, in the present study the kinetic behavior of self-reducing pellets containing elephant grass coal and iron ore was investigated through kinetic isotherms for different temperatures. The pellets were isothermally treated in different time intervals for X-Ray diffraction and SEM analyzes. The results obtained by XRD showed that the higher mass of iron in the sample was achieved until the first 24 min. The SEM analysis allowed visualizing the presence of a metallic porous structure closer to edge and whiskers in the center of sample.
Three-Dimensional Microstructure Reconstruction and Phase Boundary by Serial Sectioning and Numerical Approach
Authors: Nogueira Daniele Aparecida , Lopes Aline Aguiar , Conegundes Wesley Luiz , Silva Fabiane Roberta Freitas , Rodrigues Daniel , de Castro Jose Adilson
Published: July 2017

The microstructure and pores of the consolidated powder materials are important to determine the final properties of the pieces produced. Therefore, the control of their volume fractions and morphologies represent actual technological challenges. Besides the quantification of the phase and pores volume fractions there are important features related with the morphological aspects and the phase boundary structure that reveals the mechanisms of properties improvements, which are crucial for development of materials obtained by powder metallurgy techniques. In this paper, stereological measurements of pores present in the material stainless steel (316L) are obtained by combining serial sectioning technique and optical microscopy (OM). Dilatometric experiments were carried out in order to simulate heat treatment for sintering the material. The 3D microstructures are obtained by images reconstruction using numerical pixels treatment and stereological results of the porosities are presented.
Effect of Isothermal on the Heat Treatment of Ag/Bi2212 Superconducting Tapes
Authors: Bigansolli Antonio Renato , Rodrigues Jr. D.
Published: July 2017

Tapes of Ag/Bi2212 (Bi2Sr2CaCu2O8+δ) have been revealed as promising materials for superconducting applications at low temperatures (4.2 K using liquid helium or 20 K using a cryocooler) and high fields (above 10 T). The reaction and formation of phases are related to the ceramic densification and to the alignment of the grains, important for the improvement of the superconductor transport properties. In the present work, it is analyzed the influence of long isotherms at the temperature of 830 °C on the superconducting properties of Ag/Bi2212 samples. The heat treatments consisted of the use of two maximum temperatures of treatment (890 °C and 905 °C), with two different soaking times, both with an annealing isotherm at 830 °C for 5 h, 30 h, and 50 h.
Microstructural Features of Sn-3.0Ag-0.7Cu Alloy Prepared by Conventional and Microwave Sintering
Authors: Turssi Caio P. , Soyama Juliano , Gunnewiek Rodolfo F. K. , Spinelli José Eduardo , Kiminami Claudio Shyinti , Kiminami Ruth H.G.A.
Published: July 2017

In the present contribution, atomised Sn-3.0Ag-0.7Cu powder alloy with a size of less than 250 μm was first compacted and then microwave and conventionally sintered at 175 °C for 15 and 120 minutes, respectively. Despite the very different processing times applied, the degree of porosity was very similar, i.e., around 7%. The as-atomized microstructure of the conventionally sintered samples was barely altered with β-Sn dendritic matrix comprising Cu6Sn5 and Ag3Sn intermetallic particles. The microwave sintered Sn-3.0Ag-0.7Cu sample exhibited a combination of fine and very coarse intermetallic particles, with the presence of well-developed needle-like Ag3Sn, and its dendritic pattern disappeared completely. The Vickers hardness of both samples was measured and found to be consistent with their microstructures.
Characterization of Atomized Powders and Extruded Samples of an Al-Si-Cu Alloy
Authors: Triveño Rios Carlos , Bolfarini C. , Botta Filho Walter José , Kiminami Claudio Shyinti
Published: July 2017

In this work, the microestrutural characterization and mechanical properties of atomized Al-9Si-3Cu alloy powders and extruded samples are presented. The microstructure was evaluated by a combination of X-ray diffraction, optical microscopy and scanning electron microscopy. The mechanical properties of extruded samples were also characterized by tensile test and hardness measurements. The results revealed that the powder particles and the extruded samples are constituted by α-Al, intermetallic and metastable phases. The extruded samples obtained by the use of smaller atomized particles show lower ductility than with larger particles. The same behavior was observed with low extrusion temperature than with high temperatures. It was also observed minor variations in the yield strength and hardness with variation in the size of the powder particles.
Analysis of the Iron Ore Pellet Mechanical Behavior under Biaxial Compression
Authors: Rodrigues Filho Jorge Franklin Mansur , dos Santos Freitas Maria Carolina , Vitoretti Flavia de Paula , de Castro Jose Adilson , da Fonseca Gláucio Soares
Published: July 2017

The increasing global demand for iron ore pellets has made the pelletizing companies to step up their investments. The mechanical strength of the pellets, as well as its wear resistance are important factors to characterize the mechanical behavior. These properties are influenced by the type and nature of the ore or concentrate, the additives and the subsequent heat treatment used. This paper develops a numerical finite element model in order to characterize the mechanical behavior of iron ore pellets. The biaxial compressive stress was analyzed in this study. The results show that the pellet subjected to biaxial stress supports higher levels of stress and strain when compared to uniaxial efforts. Accuracy increase of the simulation results can be obtained with the implementation of a failure criterion for brittle materials in the numerical model. Finally, could be seen that the pellet had higher levels of deformation under biaxial symmetric strain, when compared with the uniaxial compression results.
High-Energy Ball Milling and Subsequent Heat Treatment of Ti-Cu-Si-B Powders
Authors: Ferreira Lucas , Fernandes Bruno Bacci , Ueda Mario , Ramos Alfeu Saraiva
Published: July 2017

Metal matrix multicomponent alloys and others based on the Ti+Ti6Si2B phases are potentially attractive for structural applications. However, there is limited information in literature on the effect of alloying in stability of the Ti6Si2B compound, which presents its single-phase region close to Ti-22Si-11B alloy composition (at.-%). In this sense, this work discusses on the effect of copper addition on the stability of the Ti6Si2B compound. Elemental powder mixtures were used to prepare the Ti-xCu-22Si-11B (x=2 and 6 at.-%) alloys by high-energy ball milling and subsequent heat treatment (1100oC for 240 minutes). The as-milled Ti-Cu-Si-B powders and heat-treated samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). Similar behavior was noted during ball milling of Ti-Cu-Si-B powders, i.e., the Ti5Si3 phase was formed after milling for 180 minutes. The mechanically alloyed and heat treated Ti-2Cu-22Si-11B alloy presented a matrix of Ti6Si2B dissolving close to 2 at.-% Cu. Precipitates of Ti5Si3 and other unknown Cu-and Fe-rich phase were also identified in microstructures of these quaternary alloys, whose amounts were increased in the mechanical alloyed and heat treated Ti-6Cu-22Si-11B alloy.
Influence of Rock Chemical Composition in Microwave Heating and Decontamination of Drill Cuttings
Authors: Petri Jr. Irineu , dos Santos Jéssika Marina , Rossi Arley Silva , Pereira Marina Seixas , Duarte Claudio Roberto , Ataíde Carlos Henrique
Published: July 2017

Drill cuttings generated by oil and gas drilling process are incorporated into the drilling fluid to ensure an efficient drilling and solids removal. The drilling rigs have a separation system accountable for separating drill cuttings and drilling fluids. Microwave drying is a new technology of separation that has been studied as an alternative to the currently drill cuttings dryer used. The results obtained in preliminary studies showed that this microwave drying is sensitive to different oxides presents into the rock. Thus, this study aimed to describe the microwave heating kinetics of some rocks in order to verify the interaction of oxides with electromagnetic waves. For this, the oxide contents of the rocks were determined by X-ray Fluorescence and different rocks were heated in a microwave heating unit. The results showed that the relationship between the temperature and heating time is exponential and depends on the rock oxide contents. It was found that the iron oxides may be unstable at microwave and rocks with high levels of magnesium oxides and sulfates tend to be good absorbers of microwave. Rocks containing high levels of calcium, silicon, titanium, barium and chloride (NaCl) are not good absorbers of microwave. It was also noted that faster solid heating, lesser the efficiency of microwave drying.
A Finite Element Analysis for an Iron Ore Pellet Compression Test
Authors: dos Santos Freitas Maria Carolina , Vitoretti Flavia de Paula , Rodrigues Filho Jorge Franklin Mansur , Silva Viviane Lima , de Castro Jose Adilson , Moreira Luciano Pessanha
Published: July 2017

The increasing global demand for iron ore pellets has made the pelletizing companies to step up their investments. The mechanical strength of the pellets, as well as its wear resistance are important factors to characterize the mechanical behavior. These properties are influenced by the type and nature of the ore or concentrate, the additives and the subsequent heat treatment used. This paper develops a numerical finite element model in order to characterize the mechanical behavior of iron ore pellets. The main objective of this study was to establish a valid finite element model that is able to simulate the mechanical behavior of iron ore pellets. The uniaxial compression test was made to evaluate the mechanical properties of the pellets. Furthermore, modeling and simulations are done using the software ABAQUS CAE® for uniaxial compression using the material properties obtained by the test. Lastly, in order to validate the model, the experimental data is crossed with the simulation results to discuss its correlation and particularities.
Characterization of Mn0.67Zn0.33Fe2O4 Nanoparticles Synthesized under Different pH
Authors: Ichikawa Rodrigo Uchida , Yoshito Walter Kenji , Saeki Margarida Juri , Maranhão Willian C.A. , Goulart Fátima , Martinez Luís Gallego
Published: July 2017

Nanostructured Mn-Zn ferrites were synthesized using co-precipitation in alkaline solution with different pH. The samples were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), thermal analysis (TG-DTA), dynamic light scattering (DLS) and scanning electron microscopy (SEM) techniques. Monophasic nanoparticles were formed when synthesized with pH 10.5. This sample was heat-treated and its XRD data was refined by the Rietveld method. Mean crystallite sizes and microstrains were determined from X-ray line profile analysis using Single-Line and Warren-Averbach methods, which revealed a mean crystallite size of approximately 10 nm and negligible microstrains. Zn content was estimated using refined cell parameters, giving a value of 33 at %, in accordance with XRF result. TG-DTA revealed that the incorporation of α-Fe2O3 occurs around 1130 °C and 1200 °C with recrystallization of the Mn-Zn ferrite spinel phase. DLS showed that mean particle size increase with temperature up to 1159 nm at 800 °C. SEM analysis showed the samples agglomerate and present similar morphology with negligible size changing when calcined between 280 °C and 800 °C. However, the sample calcined at 1200 °C presents larger agglomerates due to the sintering process.
Sintering of AISI M2 Tool Steel Processed in High-Energy Planetary Mill
Authors: Hupalo Marcio Ferreira , Vurobi Jr. Selauco , Namur Ricardo Sanson , Diniz Isabela Rodrigues , Cintho Osvaldo Mitsuyuki
Published: July 2017

This work aimed to evaluate the effect of pre-sintering annealing heat treatments and sintering times in AISI M2 high-speed steel powders processed by high energy milling. Turning chips were obtained from an AISI M2 drill bit that was annealed during 2 hours at 900°C, under argon atmosphere, before machining. Subsequently, the chips were milled during 10 hours in a high energy planetary mill with a power ratio of 10:1, also under argon atmosphere. Half of the powder mass was annealed at 650oC during 30 minutes under argon atmosphere after milling. Three different samples were prepared, consisting of: non-annealed powder, annealed powder and a mixture 1:1 of annealed and non-annealed powders. All powders were compacted by uniaxial pressing before sintered. Compressibility curves were obtained for all samples. Sintering process was conducted at 1200°C during 1, 2 and 3 hours and samples were cooled inside the furnace. The annealed powder sample presented the best compactation behavior, due to its restored ductility, followed by the 1:1 mixture of annealed and non-annealed powders. The microstructure of sintered samples displayed a ferritic matrix surrounded by carbide networks at grain boundaries. Higher sintering times resulted in carbon impoverishing, leading to lower volume fractions of carbides and hence reducing its hardness. Non-annealed powders showed higher dependency of sintering time to reduce their porosity. The best results were obtained for the annealed powder with shorter sintering time, since it presented low volume fraction of porosities and smaller grain sizes.
Development of Aluminium Foam through the Sintering Dissolution Process from the Alloy AA 3104
Authors: Oliveira Mariana Carvalho , Coelho Rodrigo Estevam
Published: July 2017

The increasing demand for lightweight materials capable to absorb impact energy has driven the growth of scientific research in the metallic foams field. This paper aims to investigate the possibility to obtain Al foams from recycled aluminium alloy through the sintering dissolution process (SDP) with sodium chloride (NaCl) as space holder. Aluminium scraps from AA 3104 alloy were powdered by high energy ball milling. Alloy powder was mixed with variable weight fraction of NaCl. The mixtures were die-pressed at room temperature and then sintered at 680°C. In the following step sintered parts were immersed in boiling water to obtain the aluminium foam. Foam microstructure was characterized by scanning electron microscopy and chemical composition was analyzed by energy dispersive spectroscopy. In addition, the residual NaCl was quantified and the foam density was determined by hydrostatic method. Best result was obtained with 60 wt% of NaCl, given a relative foam density of 30%, which in turn justifies further studies with metallic foams from aluminium scraps.
Effect of Liquid Phase during Sintering on Mechanical and Tribological Properties of Self-Lubricating Composites
Authors: Steinbach Renata , Bendo Tatiana , Hammes Gisele , Binder Cristiano , de Mello José Daniel Biasoli , Klein Aloísio Neumo
Published: July 2017

The present work aimed to contribute to the development of high performance self-lubricating sintered composites, with low friction coefficient and high mechanical strength. Self-lubricating composites presenting embedded solid lubricants in a ferrous matrix were produced. Hexagonal boron nitride (hBN) and graphite were the solid lubricants powders added during the mixing step. The composites were processed by conventional powder metallurgy. The liquid phase sintering, by adding copper, improved the degree of continuity of the matrix by rearranging the solid lubricant particles. With this, besides the hardening effect on the matrix, the mechanical properties of the composites were improved, with tensile strength increasing when compared to the same composite without copper. By using the proposed methodologies, optimized composites presenting friction coefficient of 0.12, tensile strength of 500 MPa and scuffing resistance of 29300 N.m were obtained.
Magnetite Nanoparticles Study Applied to Magnetic Hyperthermia Treatment
Authors: Paresque Mara Carolina do Carmo , de Oliveira Elizabeth Mendes , Nogueira Daniele Aparecida , de Castro Jose Adilson , de Campos Marcos Flavio
Published: July 2017

The functionalization of superparamagnetic iron oxide (SPIO) nanoparticles with bioactive molecules enables new applications of these nanomaterials due to their magnetic properties, which is affected by the surface coating of the nanoparticles. In this work, Fe3O4 nanoparticles type / core layer were synthesized by co-precipitation wet method and coated with a polymer mixture of polyethylene glycol (PEG). It was performed a study about duration in encapsulation of nanoparticles in their final size in order to get different thickness of coated layer and varied coating properties. With this study was expected to obtain different thicknesses and thus the coating properties. Five samples were synthesized according to the same procedure and amount of reactants used synthetic sequence for all samples, only varying the time spent by each sample coating process with polyethylene glycol. The different times for the coating samples were 10 minutes, 20 minutes, 30 minutes, 50 minutes and finally 60 minutes. The nanoparticles were characterized by Nanosight, TGA and DSC techniques. The results showed that the particle size suffers an increase during the first 30 minutes of duration of the coating step and then stabilizes.
Consolidation Behavior and Magnetic Properties of Nanocrystalline Nd-Fe-B Magnets Prepared by Spark Plasma Sintering
Authors: Keller Frederico Orlandini , Engerroff Juliano Assis Baron , Lopes Leonardo Ulian , Vicente Jr. Nério , Wendhausen Paulo Antônio Pereira
Published: July 2017

Spark Plasma Sintering (SPS) was studied as a means to consolidate Nd-Fe-B powders, previously subjected to grain refinement by HDDR (Hidrogenation–Disproportionation–Dessorption–Recombination). The sintering process was carried out under 60 MPa constant pressure, varying the maximum processing temperature from 500 °C to 900 °C with a holding time of 5 min. Densification was observed above 600 °C related to the melting of Nd-rich phase. The magnetic properties are clearly related to microstructure coarsening associated with the SPS temperature regime. A monotonic decrease for coercivity (Hcj) was observed as a function of maximum SPS operating temperature with values varying from maximum of 750 kA/m at 500 °C to less than 200 kA/m for SPS at 900 °C. Remanence (Br) and maximum energy product (BH)max showed optimum values for intermediate temperatures, since these properties benefit from the densification developed by SPS.
d-HDDR Processing of Nd-Fe-B Based Alloys to Obtain Highly Anisotropic Nanocrystalline Powders
Authors: Engerroff Juliano Assis Baron , Keller Frederico Orlandini , Lopes Leonardo Ulian , Mascheroni Arthur Alvarez , Takiishi H. , Wendhausen Paulo Antônio Pereira
Published: July 2017

The HDDR (hydrogenation-disproportionation-desorption-recombination) process is an established powder metallurgy route to obtain Nd–Fe–B nanocrystalline powders for bonded magnets manufacturing. Therefore, both conventional (c-HDDR) and dynamic HDDR (d-HDDR) processes has been investigated to obtain Nd-Fe-B-based powders with different characteristics. Magnetic properties were measured by means of a hysteresisgraph and the powder obtained by d-HDDR showed strong anisotropy, allowing a Br of 1.1 T in the bonded magnet, whereas c-HDDR powder was isotropic with a Br of 0.6 T. Microstructural changes were characterized by X-ray diffraction (DRX) and scanning electron microscopy (SEM). X-ray patters of anisotropic powders made by d-HDDR showed high intensity reflection peaks indexed as (004), (105) and (006) planes in the aligning direction, due the texture inducement in c-axis of the main phase (Nd2Fe14B). However, SEM micrographs of c-HDDR powder showed a more homogeneous microstructure, with grain size of ~300 nm, when compared to d-HDDR powder that ranged from 300 nm to 500 nm. This difference is assumed to be the cause of lower intrinsic coercivity found in the c-HDDR powder.
Hydrothermal Synthesis and Characterization of Zeolite A Using Amorphous Gel from Industrial Reagents
Authors: Moreira Jarina Costa , Koslowski Luciano André , Boca Santa Rozineide A. Antunes , Macuvele Domingos Lusitâneo Pier , Riella Humberto Gracher
Published: July 2017

Zeolites are crystalline microporous aluminosilicate of alkali metals and alkaline-earth metals. These materials have large commercial application due to their physical and chemical properties. The synthesis of zeolite A was carried out based on procedures described by International Zeolite Association (IZA), the sodium silicate was used as a source of silicon and the sodium aluminate as a source of aluminum for the produced zeolite. The synthesis occurred at hydrothermal conditions through static autoclaving. The material formed was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results obtained from the characterization analysis were satisfactory and the method of synthesis showed to have high reproducibility in the production of zeolite A with good crystallinity as predominant phase. This result is very interesting because this method is simple and did not use toxic organic compounds as templates.
Numerical Simulation and Experimental Study of Particle Dynamics in a Rotating Drum with Flights
Authors: Nascimento Suellen Mendonça , de Lima F.P. , Duarte Claudio Roberto , Barrozo Marcos A.S.
Published: July 2017

Rotary dryers are widely used in various industries. Although numerous research efforts have focused on characterizing the dynamics of these equipments, the design of rotating dryers is complex, and theoretical studies are necessary to gain an in-depth understanding of the dynamics of particles in these dryers. This paper aims to investigate the particle dynamic behavior in a rotating drum with flights, based on CFD and experimental results. In the numerical study it was used the Eulerian-Eulerian multiphase model along with the kinetic theory of granular flow. The holdups of solids in the flights were compared with experimental data, using a methodology created specifically for this purpose. The simulated results were in good agreement with the experimental data and the present work has shown that the Eulerian approach has been able to predict the fluid dynamics behavior in different operating conditions.
Effect of Surfactant on Bubble Size and Air Holdup on Column Flotation
Authors: Reis Angelica Silva , Filho A.M.R. , Carvalho G.R.L. , Barrozo Marcos A.S.
Published: July 2017

Flotation is a complex process in which is present physicochemical and hydrodynamic phenomena. The flotation performance is related to the probability of bubble-particle collisions and stability of aggregate formed. The collision efficiency is a function of particle and bubble diameters. Currently one of the biggest challenges of the mining industry is the flotation of fine and ultrafine particles and a possible solution to increase the recovery of these fine particles is the use of bubbles with intermediate size (100-1000μm). Therefore, determining and controlling the bubble size is very important for further recoveries in the flotation of fine particles. It is known that the bubble size and air holdup are influenced by variations on the superficial gas velocity and by addition of surfactants. Thus this work aimed to study the effect of adding surfactants on bubbles formation. The results showed that the addition of surfactant was a good alternative to decrease bubble size and increase the air holdup in a bubble column. Three different surfactants had similar behavior on bubble size and holdup. It was possible to define the range of concentration values which are sufficient for forming bubbles with intermediate size and holdup within the range recommended for mineral flotation.
Sucrose Crystallization in Vibrated Bed Process, Unusual Crystallizer Configuration
Authors: Quintino Davi Batista , Malagoni Ricardo Amâncio
Published: July 2017

Through yield and Sauter mean diameter, the sucrose crystallization was studied in vibrated bed equipment, in which, supersaturation degree, dimensionless vibration number and crystallization time were independent variables. A central composite design with seventeen trials was performed in order to ascertain the influence of each variable in both responses, the crystallization temperature and the amount of seeds were kept constant. The crystallization vibration system differs from the usual configuration, consisting of two perforated discs made of stainless steel, one loop and three aluminum rings. By canonical analysis, it was obtained the operating condition which maximizes the yield and average crystal size. Surface responses were also obtained according to the relevance of each variable, in which were evidenced the high supersaturation and vibration influence for both factors, the high quadratic term of all variables on the crystal yield, and also highlights the great interaction between supersaturation and the dimensionless vibration number.
Structural Evaluation of Mechanically Alloyed W-50at%C Powders
Authors: de Alencar e Silva Gustavo Souza , Neto Ricardo Mendes Leal , Henriques Vinícius André Rodrigues , Cairo Carlos Alberto Alves , Ramos Alfeu Saraiva
Published: July 2017

Tungsten carbide is potentially attractive for development of catalysts and widely used for fabrication of cutting tools due to its high hardness and wear resistance while the ball milling can improve the mechanical properties from the metastable structures and nanomaterials. The aim of this work was to evaluate the phase transformations during milling of the W-50at%C elemental powder mixture under argon atmosphere in a planetary P-5 ball mill using WC-Co balls (10 mm diameter) and vials (225 mL), 200 rpm, and a ball-to-powder weight ratio of 10:1. Samples were collected into the vial after different times: 20, 60, 300 and 600 min. The as-milled W-50at%C powders were characterized by X-ray diffraction (XRD). Only peaks of W were identified in W-50at%C powders milled up to 600 min, which were broadened and moved to the direction of smaller diffraction angle. In addition, the lattice parameter and cell volume of W were reduced during ball milling of W-50at%C powders, indicating that the C atoms dissolved into the W lattice in order to form metastable structures. Carbon atoms were interstitially dissolved into the W lattice during the initial milling times, and its preferential substitutional dissolution was identified for longer times due to the larger amounts of crystallographic defects during ball milling.
CFD Simulation of Spouted Bed Working with a Size Distribution of Sand Particles: Segregation Aspects
Authors: dos Santos Kássia Graciele , Ferreira L.V. , Santana Ricardo Correa , Barrozo Marcos A.S.
Published: July 2017

Spouted bed simulations are usually performed using only one granular phase with a mean particle diameter representing the entire particle mixture, instead of a particle size distribution. In this study, the effect of the particle size distribution is accounted through the simulation of a mixture with five granular phases. The results showed that the particle segregation occurs. Larger particles are more concentrated in the upper region, while the smaller particles are preferably positioned in the lower region of the bed. Computational simulation using CFD method reproduced well the segregation experiments with different participle sizes of sand.
Modelling beta diversity of aquatic macroinvertebrates in High Andean wetlands
Authors: Nieto Carolina , Dos Santos Daniel A. , Izquierdo Andrea E. , Rodríguez José S. , Grau Héctor R.
Published: July 2017

Central Andean Highlands represent a singular environment characterized by various extreme conditions. Among them, peatbogs are exceptional marshy habitats scattered throughout this arid and harsh area. In an effort to understand the patterns of beta diversity, we sampled the benthic macroinvertebrates of thirteen peatbogs and related the biological distance with ecological distance using the GDM (Generalized Dissimilarity Modelling) approach. Variables analyzed were altitude, geographical distance, physical and chemical parameters of the water. A coefficient based on the ordering properties of count data, from the perspective of both sites and taxa, was used to measure the compositional similarity between samples. The most frequent taxa were: Hyallela, Simuliidae, Andesiops, Austrelmis, Podonominae, Protallagma, Trichocorixa, Orthocladiinae and Glossiphonidae. The highest altitudinal record ever for leeches is reported here. Altitude and conductivity contributed greatly to the single ecological predictor of beta diversity. Sampling points can be classified first by altitude (cutoff sets at 4,200 m), which can be considered a surrogate of a regional factor (distinction between Puna and High Andean ecoregions) and then by conductivity (cutoff sets at 135 µS cm-1), which can be considered a proxy of a local factor (distinction between hyperfresh and more mineralized habitats). These results suggest a system of ecological filters acting on them. 
Fisheries impacts on lake ecosystem structure in the context of a changing climate and trophic state
Authors: Nõges Tiina , Anneville Orlane , Guillard Jean , Haberman Juta , Järvalt Ain , Manca Marina , Morabito Giuseppe , Rogora Michela , Thackeray Stephen J. , Volta Pietro , Winfield Ian J. , Nõges Peeter
Published: July 2017

Through cascading effects within lake food webs, commercial and recreational fisheries may indirectly affect the abundances of organisms at lower trophic levels, such as phytoplankton, even if they are not directly consumed. So far, interactive effects of fisheries, changing trophic state and climate upon lake ecosystems have been largely overlooked. Here we analyse case studies from five European lake basins of differing trophic states (Lake Võrtsjärv, two basins of Windermere, Lake Geneva and Lake Maggiore) with long-term limnological and fisheries data. Decreasing phosphorus concentrations (re-oligotrophication) and increasing water temperatures have been reported in all five lake basins, while phytoplankton concentration has decreased only slightly or even increased in some cases. To examine possible ecosystem-scale effects of fisheries, we analysed correlations between fish and fisheries data, and other food web components and environmental factors. Re-oligotrophication over different ranges of the trophic scale induced different fish responsesIn the deeper lakes Geneva and Maggiore, we found a stronger link between phytoplankton and planktivorous fish and thus a more important cascading top-down effect than in other lakes. This connection makes careful ecosystem-based fisheries management extremely important for maintaining high water quality in such systems. We also demonstrated that increasing water temperature might favour piscivores at low phosphorus loading, but suppresses them at high phosphorus loading and might thus either enhance or diminish the cascading top-down control over phytoplankton with strong implications for water quality.
Field application of the Micro Biological Survey method for the assessment of the microbiological safety of different water sources in Horn of Africa and the evaluation of the effectiveness of Moringa oleifera in drinking water purification
Authors: Losito Francesca , Arienzo Alyexandra , Somma Daniela , Murgia Lorenza , Stalio Ottavia , Zuppi Paolo , Rossi Elisabetta , Antonini Giovanni
Published: July 2017

Water monitoring requires expensive instrumentations and skilled technicians. In developing Countries as Africa, the severe economic restrictions and lack of technology make water safety monitoring approaches applied in developed Countries, still not sustainable. The need to develop new methods that are suitable, affordable, and sustainable in the African context is urgent. The simple, economic and rapid Micro Biological Survey (MBS) method does not require an equipped laboratory nor special instruments and skilled technicians, but it can be very useful for routine water analysis. The aim of this work was the application of the MBS method to evaluate the microbiological safety of different water sources and the effectiveness of different drinking water treatments in the Horn of Africa. The obtained results have proved that this method could be very helpful to monitor water safety before and after various purification treatments, with the aim to control waterborne diseases especially in developing Countries, whose population is the most exposed to these diseases. In addition, it has been proved that Moringa oleifera water treatment is ineffective in decreasing bacterial load of Eritrea water samples.
Publication practices and responsible authorship: a review article
Authors: Tarkang Elvis E. , Kweku Margaret , Zotor Francis B.
Published: July 2017

Dissemination of research findings through the publication of one’s work or a group of contributors is an important part of the research process, as this allows the passing on of benefits to a much wider community. In whatever evocative form this dissemination may take, the onus lies on the author(s) to ensure adherence to the code of ethics as it pertains to the integrity of the information being put out. We publish because we want our findings to be adapted into practice and application, or in some cases may be relevant to policy makers in decision-making. To a large extent in the field of academia, successful publication improves opportunities for academic funding and promotion whilst enhancing scientific and scholarly achievement and repute. A situation may be compromised where intellectual contributions to a scientific investigation do not adhere to the four key guidelines of scholarship, authorship, approval and agreement as well as the protocols of ensuring good publication ethics. The objective of this review is to lay emphasis on universal standards for manuscript authorship and to fostering good practices. This in our view will bring authorship credit and accountability to the attention of our colleagues and readers at large. To achieve this, a systematic and critical review of the literature was undertaken. Electronic databases, academic journals and books from various sources were accessed. Several key search terms relating to responsible authorship, common authorship malpractices, conflict of interest, universal publication guidelines and other authorship related issues, were used. Only references deemed useful from relevant texts and journal articles were included. In this paper, the authors have sought to highlight the pitfalls researchers sometimes entangle themselves within an act of compromise thereby impinging on the ethical and professional responsibilities for the content of a paper under consideration. This article presents the case that authorship has a strong currency that brings not only personal satisfaction but also career rewards based on publication counting. In all cases described here, a universal standard for manuscript authorship will be critical in fostering good practices. As you write and review manuscripts, keep these good practices in mind, and consider ways to bring authorship credit and accountability to the attention of your colleagues and readers.
Sentinel node biopsy in vulvar cancer: A critical appraisal
Authors: Hacker Neville , Barlow Ellen
Published: July 2017

Since the incorporation of inguinal-femoral lymphadenectomy into the management of patients with vulvar cancer in the mid-20th century, there have been attempts to modify or eliminate the groin dissection to decrease the risk of lower limb lymphedema. Early attempts were significantly flawed and resulted in much unnecessary loss of life because recurrence in an undissected groin is usually fatal. The best compromise yet to decrease the risk of lymphedema is sentinel node biopsy, but accumulated evidence now suggests that the false-negative rate for this procedure, if used for lesions up to 4 cm in diameter, is between 5% and 10%. Most women, properly informed of risks and benefits, are not prepared to take a 1% risk of dying from recurrent vulvar cancer to avoid lymphedema. This is the risk involved, assuming a false-negative rate of 5% and an incidence of positive nodes of 20%. For this reason, sentinel node biopsy should not be considered to be standard practice for patients with early vulvar cancer.
Role of squamous cell carcinoma antigen in monitoring of treatment response of cervical and vaginal malignancies
Authors: Sachan Rekha , Patel Munna Lal , Singh Meenakshi , Sachan Pushpalata , Shyam Radhey
Published: July 2017

Introduction: As per GLOBOCAN 2012 report Worldwide fourth most common cancer in the female is cervical cancer and approximately 528,000 new cases was found in 2012 in large majority of global burden was found in less developed country. India, the second most populous country in the world, accounts for 27% of the total cervical cancer deaths. The aim of this study was to assess the efficacy of squamous cells carcinoma antigen (SCC-Ag) in monitoring of response to treatment in cervical and vaginal cancer patients.

Materials and Methods: This prospective case–control study was carried out over a period of 1 year in the Department of Obstetrics and Gynecology in collaboration with the Department of Internal Medicine and Pathology. Histopathologically confirmed study group included 8 cases of Stage I, 15 cases of Stage II, 15 cases of Stage III, 8 cases of Stage IV cervical malignancy, and 5 cases of vaginal carcinoma. About 15 healthy cervical cytology-negative women were taken as controls.

Results: Out of 51 cancer cases SCC-Ag level were determined in only Stage I, II, III, and IV cases, assess the response to treatment. The mean SCC-Ag level in all four stage groups decreased significantly after post treatment as compared to pre treatment (P < 0.001) and the decrease in post treatment SCC-Ag level increased linearly with stage severity. Similarly, comparing the total or overall (Stage I + Stage II + Stage III) mean change (pre-post) in SCC-Ag level, t-test further revealed significant (P < 0.001) and decrease of 66.2% at posttreatment as compared to pretreatment.

Conclusion: SCC-Ag might be a useful marker in monitoring the response to treatment.
Weekly versus biweekly high-dose rate brachytherapy schedules in carcinoma cervix following concomitant chemoradiation with paclitaxel and carboplatin
Authors: Gogia Pooja , Dhull Anil , Kaushal Vivek
Published: July 2017

Context: In the management of cervical cancer, though a number of chemotherapeutic drugs have been used for concomitant chemoradiation, paclitaxel and carboplatin have shown improved overall response rates with acceptable side effects. The use of intracavitary irradiation significantly improves survival and reduces local failures. However, the ideal time-dose-fraction schedule remains controversial with high-dose rate (HDR) brachytherapy.

Aims: The aim of this study was to determine the efficacy and safety of paclitaxel and carboplatin for concomitant chemoradiation therapy and to compare the local control, toxicity, and tolerability of the two HDR brachytherapy schedules in patients of carcinoma cervix.

Subjects and Methods: The patients were divided randomly into two groups of thirty patients each. Both the groups were treated with a combination of external beam radiotherapy with 50 Gy/5 weeks/25 fractions to whole pelvis along with concomitant chemotherapy. The concomitant chemotherapy schedule was injection paclitaxel (135 mg/m2) and injection carboplatin (area under the curve - 4.5 mg min/ml) at 4-week interval followed by HDR brachytherapy. Following which, patients received HDR-intracranial brachytherapy on the basis of random allocation, Group I: 6 Gy × 3 fractions (weekly) and Group II: 5 Gy × 4 fractions (biweekly).

Results and Conclusion: The survival difference between the two groups (weekly and biweekly) was not statistically significant. However, Grade 2–3 rectal reactions in Group I were significantly higher than Group II (P = 0.038). The twice-weekly schedule of brachytherapy was a significant factor influencing the late complication rate but not the local pelvic control rate or overall survival rate.
A New Proof of the Hansen—Mullen Irreducibility Conjecture
Authors: Tuxanidy Aleksandr , Wang Qiang
Published: July 2017

We give a new proof of the Hansen–Mullen irreducibility conjecture. The proof relies on an application of a (seemingly new) sufficient condition for the existence of elements of degree n in the support of functions on finite fields. This connection to irreducible polynomials is made via the least period of the discrete Fourier transform (DFT) of functions with values in finite fields. We exploit this relation and prove, in an elementary fashion, that a relevant function related to the DFT of characteristic elementary symmetric functions (that produce the coefficients of characteristic polynomials) satisfies a simple requirement on the least period. This bears a sharp contrast to previous techniques employed in the literature to tackle the existence of irreducible polynomials with prescribed coefficients.
Smoothing Properties and Scattering for the Magnetic Schrödinger and Klein–Gordon Equations in an Exterior Domain with Time-Dependent Perturbations
Authors: Mochizuki Kiyoshi , Murai Sojiro
Published: July 2017

This paper deals with the existence, smoothing properties and scattering of solutions to the magnetic Schrödinger and Klein–Gordon equations in an exterior domain with time-dependent small perturbations. Smoothing properties based on the resolvent estimates will reinforce the abstract scattering theory developed in [8] (K. Mochizuki, in
Proc. 6th ISAAC
, World Scientific Publishing, River Edge, NJ, 2009, 476–485), and our concrete problems are treated in this framework.
Twisted Alexander Polynomials of Hyperbolic Links
Authors: Morifuji Takayuki , Tran Anh T.
Published: July 2017

In this paper we apply the twisted Alexander polynomial to study fibering and genus detecting problems for oriented links. In particular we generalize a conjecture of Dunfield, Friedl and Jackson on the torsion polynomial of hyperbolic knots to hyperbolic links, and confirm it for an infinite family of hyperbolic 2-bridge links. Moreover, we consider a similar problem for parabolic representations of 2-bridge link groups.
Квазидетерминантные решения расширенной некомутативной иерархии Кадомцева-Петвиашвили
Authors: Wu Hongxia , Liu Jingxin , Li Chunxia
Published: July 2017

Построено преобразование Дарбу для расширенной некоммутативной иерархии Кадомцева-Петвиашвили, не являющееся автопреобразованием, и, как следствие, получено выраженное через квазивронскиан решение, а также построено выраженное через квазивронскиан решение для некоммутативной иерархии Кадомцева-Петвиашвили c самосогласованными источниками. Для доказательства того, что найденные квазидетерминантные решения действительно являются решениями уравнения некоммутативной иерархии Кадомцева-Петвиашвили c самосогласованными источниками, использован метод прямой проверки.
Intestinal Parasitic Infections in Human Immunodeficiency Virus-Infected and Noninfected Persons in a High Human Immunodeficiency Virus Prevalence Region of Cameroon
Authors: Nkenfou Céline Nguefeu , Tchameni Sandrine Mboula , Nkenfou Carine Nguefeu , Djataou Patrice , Simo Ulrich Florian , Nkoum Alexandre Benjamin , Estrin William
Published: July 2017

The problem of intestinal parasitic infection in human immunodeficiency virus (HIV)–infected people requires careful consideration in the developing world where poor nutrition is associated with poor hygiene and several coinfecting diseases. Studies have addressed this issue in Cameroon, especially in the low HIV prevalence area. The current study was conducted to determine the prevalence of intestinal parasitosis in people living with HIV (PLHIV) in Adamaoua and to identify associated risk factors. Stool and blood specimens from study participants were screened for intestinal parasites and anti-HIV antibodies, respectively. Of 235 participants, 68 (28.9%) were HIV positive, 38 of them on antiretroviral treatment (ART). The overall prevalence of intestinal parasites was 32.3%. Of 68 PLHIV, 32.3% (22/68) were infected with intestinal parasites, compared with 32.3% (54/167) of the HIV-negative patients. Univariate analysis showed no difference between the prevalence of intestinal parasites among PLHIV and HIV-negative patients (P = 0.69). ART was not associated with the prevalence of intestinal parasites. Multivariate analysis showed that the quality of water and the personal hygiene were the major risk factors associated to intestinal parasitosis. The level of education was associated with HIV serostatus: the higher the level of education, the lower the risk of being infected with HIV (P = 0.00). PLHIV and the general population should be screened routinely for intestinal parasites and treated if infected.
Confucian Learning and Literacy in Japan’s Schools of the Edo Period
Authors: HMELJAK SANGAWA Kristina
Published: July 2017

With the political stability, economic growth and cultural revitalisation of Japan after its unification by Tokugawa Ieyasu, the educational infrastructure also grew to meet new literacy demands. Governmental schools endowed by the shogunate (Shōheikō) and by the domains (hankō), which catered to the upper military class of the samurai, focused on classical Chinese studies, particularly the Neo-Confucian canon taught in kanbun, a style of classical Chinese. Given the prestige of Neo-Confucian Chinese learning and of the kanbun writing style, these were taught also in temple schools (terakoya) and private academies (juku) that were open to the lower classes, thus contributing to the spread of this particular type of literacy. However, Chinese learning in these schools often involved memorising rather than reading, both because of educational traditions and socio-ideological factors, and also because of the sheer difficulty of reading kanbun, a de facto foreign language. The present article investigates the contrasting implications of Neo-Confucian learning and of the kanbun writing style for the development of education and literacy in Japanese society: while the prestige of Chinese learning contributed to the demand for and development of educational facilities, its complexity also acted as an obstacle to the development of widespread functional literacy.