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R. Beygi,R. Carbas,A. Queiros,E. A. S. Marques,R. Shi,L. F. M. da Silva 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8
Steel (St) and aluminum (Al) have a high affinity to each other and form intermetallic compounds (IMCs) when bonded byfriction stir welding (FSW). Understanding the effect of alloying elements of steel on the formation of IMCs will help todesign joints in which the formation of IMCs is controlled. In this study, two kinds of steel, carbon steel (CS) and austeniticstainless steel (SS) with 3 mm thickness, were selected to be welded to aluminum by FSW under similar conditions. Theeffect of the rotation speed of the FSW tool was also examined in the range of 850–1300 RPM. The morphology, thickness,and composition of IMCs in the interfaces were studied by various characterization techniques. It was observed that theIMC layers in the SS/Al joints were much thinner than the ones in CS/Al joints (0.1–0.7 μm in SS/Al and 2–6 μm in CS/Al). Moreover, the thickness of IMC layer in CS/Al joints increased with increasing the rotation speed while in SS/Al jointsit began to decline by exceeding a certain rotation speed. In order to explain these differences, diffusion-based equationswere used to calculate the interdiffusion coefficients in both SS/Al and CS/Al couples. It was found that the interdiffusioncoefficient in SS/Al was lower than CS/Al. This was attributed to the alloying elements of SS such as Ni and Cr which candiffuse to IMC layer and hinder the growth rate of IMCs. It was also observed that some form of liquation occurred in SS/Al joints at high rotation speed of FSW due to the formation of a low-melting multielement compound of Al–Fe–Cr–Ni. The decline of IMC thickness in SS/Al joints at high rotation speed was attributed to this multielement compound whichwas melted during FSW and reduced the nucleation rate of Al–Fe IMCs. Finally, the fracture of the specimens and the effectof IMC formation on the joint establishment were elaborated. It was concluded that the alloying elements of steel have abeneficial effect on controlling the growth of IMCs.
Maryluce Albuquerque da Silva Campos,Fábio Sérgio Barbosa da Silva,Adriana Mayumi Yano-Melo,Natoniel Franklin de Melo,Elvira Maria Régis Pedrosa,Leonor Costa Maia 한국식물병리학회 2013 Plant Pathology Journal Vol.29 No.3
In the Northeast of Brazil, expansion of guava crops has been impaired by Meloidogyne enterolobii that causes root galls, leaf fall and plant death. Considering the fact that arbuscular mycorrhizal Fungi (AMF) improve plant growth giving protection against damages by plant pathogens, this work was carried out to select AMF efficient to increase production of guava seedlings and their tolerance to M. enterolobii. Seedlings of guava were inoculated with 200 spores of Gigaspora albida,Glomus etunicatum or Acaulospora longula and 55 days later with 4,000 eggs of M. enterolobii. The interactions between the AMF and M. enterolobii were assessed by measuring leaf number, aerial dry biomass, CO2 evolution and arbuscular and total mycorrhizal colonization. In general, plant growth was improved by the treatments with A. longula or with G. albida. The presence of the nematode decreased arbuscular colonization and increased general enzymatic activity. Higher dehydrogenase activity occurred with the A. longula treatment and CO2 evolution was higher in the control with the nematode. More spores and higher production of glomalin-related soil proteins were observed in the treatment with G. albida. The numbers of galls, egg masses and eggs were reduced in the presence of A. longula. Inoculation with this fungus benefitted plant growth and decreased nematode reproduction.
Jaqueline Correia Villac¸a,Luiz Cla´udio R. Pereira da Silva,Luisa Helena Falca˜o Barbosa,Carlos Rangel Rodrigues,Luiz Marcelo Lira,Fla´ via Almada do Carmo,Valeria Pereira de Sousa,Maria Ineˆs Bruno 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6
The purpose of this study was to prepare and characterize lamellar silicate nanocomposites usingexfoliation processes, high clay load and polyvinylpyrrolidone (PVP), ethylcellulose (EC) andpolyquaternium-H (PQH). The clays (sodium montmorillonite, Viscogel S4TM, S7TM and B8TM) werepre-treated with ultrasonic energy in order to increase clay exfoliation yields. Polymeric nanocompositeswere characterized by XRPD, DSC, TGA, DLS and NMR. The results revealed a new exfoliationmethod and new intercalated nanocomposites. High clay load was used to obtain the nanocomposites,which enables its application at an industrial scale. These nanocomposites could be broadly appliedacross the pharmaceutical, medical and food industries.
Behaviour of flush end-plate beam-to-column joints under bending and axial force
Luís Simões da Silva,Luciano R. O. de Lima,Pedro C. G. da S. Vellasco,Sebastião A. L. de Andrade 국제구조공학회 2004 Steel and Composite Structures, An International J Vol.4 No.2
Steel beam-to-column joints are often subjected to a combination of bending and axial forces. The level of axial forces in the joint may be significant, typical of pitched-roof portal frames, sway frames or frames with incomplete floors. Current specifications for steel joints do not take into account the presence of axial forces (tension and/or compression) in the joints. A single empirical limitation of 10% of the beam’s plastic axial capacity is the only enforced provision in Annex J of Eurocode 3. The objective of the present paper is to describe some experimental and numerical work carried out at the University of Coimbra to try to extend the philosophy of the component method to deal with the combined action bending moment and axial force.
Marcos R da S Vieira,Luiz G M Pessoa,Walter S E Junior,Ygor H Leal,Luzia F da Silva,Rafael C Silva,Eduardo S dos Santos,Thialla L Amorim,Damina C de Medeiros 한국원예학회 2016 Horticulture, Environment, and Biotechnology Vol.57 No.2
This study aimed to assess changes in peroxidase activity and total protein content of cut flowers of Strelitzia reginae that were treated with the chemical preservatives 8-hydroxyquinoline citrate (8-HQC) or chlorine during cold storage. The bases of the cut flowers were immersed in 1.5 L of tap water with 48 h pulsing treatments (a control with no chemical preservatives (0 mg·L-1, 100 mg·L-1 chlorine, 250 mg·L-1 8-HQC or 500 mg·L-1 8-HQC) during cold storage at 10.5°C and 90% relative humidity. The solutions were then replaced with tap water and the cut flowers remained in cold storage for 12 days. For biochemical characterization of peroxidase activity and total protein content, tissue samples (sepals, petals, stems, and bracts) were collected and analyzed at 0, 4, 8, and 12 days after treatment. There was an increase in peroxidase activity in petals, stems, and bracts and a decrease in total protein content, regardless of the treatment used. In this experiment, therefore, differences in peroxidase activity and total protein content due to treatments with 8-HQC or chlorine were not identified.
Aleksandro S. Da Silva,Vinicius R. Fanfa,Mateus A. Otto,Lucas T. Gressler,Kaio C.S. Tavares,Cicera R. Lazzarotto,Alexandre A. Tonin,Luiz C. Miletti,Marta M. M. F. Duarte,Silvia G. Monteiro 대한기생충학열대의학회 2011 The Korean Journal of Parasitology Vol.49 No.4
The aim of this study was to test the susceptibility of mice to Trypanosoma evansi treated with human plasma containing different concentrations of apolipoprotein L-1 (APOL1). For this experiment, a strain of T. evansi and human plasma (plasmas 1, 2, and 3) from 3 adult males clinically healthy were used. In vivo test used 50 mice divided in 5 groups (A to E) with 10 animals in each group. Animals of groups B to E were infected, and then treated with 0.2 ml of human plasma in the following outline: negative control (A), positive control (B), treatment with plasma 1 (C), treatment with plasma 2 (D), and treatment with plasma 3 (E). Mice treated with human plasma showed an increase in longevity of 40.9±0.3 (C), 20±9.0 (D) and 35.6±9.3 (E) days compared to the control group (B) which was 4.3±0.5 days. The number of surviving mice and free of the parasite (blood smear and PCR negative) at the end of the experiment was 90%, 0%, and 60% for groups C, D, and E, respectively. The quantification of APOL1 was performed due to the large difference in the treatments that differed in the source plasma. In plasmas 1, 2, and 3 was detected the concentration of 194, 99, and 115 mg/dl of APOL1, respectively. However, we believe that this difference in the treatment efficiency is related to the level of APOL1 in plasmas.
Effects of Castor Meal on the Growth Performance and Carcass Characteristics of Beef Cattle
Diniz, L.L.,Filho, S.C. Valadares,Campos, J.M.S.,Valadares, R.F.D.,Da Silva, L.D.,Monnerat, J.P.I.S.,Benedeti, P.B.,De Oliveira, A.S.,Pina, D.S. Asian Australasian Association of Animal Productio 2010 Animal Bioscience Vol.23 No.10
The purpose of this study was to evaluate the effect of replacing soybean meal with treated castor meal with (CMT) or without lime (CMNT) on the nutrient intake, performance, carcass characteristics, and yield of commercial cuts of beef cattle from a feedlot. Thirty male, castrated, crossbreed zebu cattle were used in the study, with an average initial weight of $360{\pm}30.27\;kg$. Five animals were used as a control group and were slaughtered at the beginning of the experiment; the remaining animals (n = 25) were distributed in random blocks (repetitions), with body weight as the criterion for block assignment. The animals were fed a diet containing 65% corn silage and 35% of concentrate on dry matter (DM) basis. Five diets consisted of four levels of soybean meal (SM) substituted with CMT (0, 33, 67 and 100%) on a DM basis and a diet with 100% of SM replaced with CMNT. At the end of the experiment, all animals were slaughtered, and their gastrointestinal tracts were emptied to determine their empty body weights (EBW). No significant effects were observed (p>0.05) for the substitution of soybean meal with CMT on intake of dietary nutrients, the average daily body weight gain (ADG) or EBW gain (EBWG). In spite of greater (p<0.05) ricin intake for the diet containing CMNT (3.06 mg/kg BW) compared to the CMT diet (0.10 mg/kg BW/d), there were no effects (p>0.05) on intake of dietary nutrients, ADG or EBWG. The average intake of DM and the ADG were 10,664.63 and 1,353.04 g/d, respectively. Regarding carcass characteristics, only carcass yield in relation to body weight was linearly reduced (p<0.05) upon substitution of SM by CMT. There was no effect (p>0.05) of the substitution of SM by CMT or CMNT on the yield of carcass basic cuts. CMT prices that are higher than 85% of the SM price do not economically justify the use of CMT. For CMT prices between 20 and 80% of the SM price, the optimal level was 67% substitution, while for prices below 15% of the SM price, the optimal level was 100% substitution with CMT. It can be concluded that treated castor meal with 6% lime can totally replace soybean meal in beef cattle diets.
Electronic structure and optical properties of BaMoO4 powders
J.C. Sczancoski,L.S. Cavalcante,N.L. Marana,R.O. da Silva,R.L. Tranquilin,M.R. Joya,P.S. Pizani,J.A. Varela,J.R. Sambrano,M. Siu Li,E. Longo,J. Andrés 한국물리학회 2010 Current Applied Physics Vol.10 No.2
Barium molybdate (BaMoO4) powders were synthesized by the co-precipitation method and processed in microwave-hydrothermal at 140 ℃ for different times. These powders were characterized by X-ray diffraction (XRD), Fourier transform Raman (FT-Raman), Fourier transform infrared (FT-IR), ultraviolet–visible (UV–vis) absorption spectroscopies and photoluminescence (PL) measurements. XRD patterns and FT-Raman spectra showed that these powders present a scheelite-type tetragonal structure without the presence of deleterious phases. FT-IR spectra exhibited a large absorption band situated at around 850.4 cm1, which is associated to the Mo–O antisymmetric stretching vibrations into the [MoO4] clusters. UV–vis absorption spectra indicated a reduction in the intermediary energy levels within band gap with the processing time evolution. First-principles quantum mechanical calculations based on the density functional theory were employed in order to understand the electronic structure (band structure and density of states) of this material. The powders when excited with different wavelengths (350 nm and 488 nm) presented variations. This phenomenon was explained through a model based in the presence of intermediary energy levels (deep and shallow holes) within the band gap.
Phase growth control in low temperature PLD Co:TiO2 films by pressure
S. Rout,N. Popovici,S. Dalui,M.L. Paramês,R.C. da Silva,A.J. Silvestre,O. Conde 한국물리학회 2013 Current Applied Physics Vol.13 No.4
This paper reports on the structural and optical properties of Co-doped TiO2 thin films grown onto (0001)Al2O3 substrates by non-reactive pulsed laser deposition (PLD) using argon as buffer gas. It is shown that by keeping constant the substrate temperature at as low as 310 C and varying only the background gas pressure between 7 Pa and 70 Pa, it is possible to grow either epitaxial rutile or pure anatase thin films, as well as films with a mixture of both polymorphs. The optical band gaps of the films are red shifted in comparison with the values usually reported for undoped TiO2, which is consistent with n-type doping of the TiO2 matrix. Such band gap red shift brings the absorption edge of the Codoped TiO2 films into the visible region, which might favour their photocatalytic activity. Furthermore,the band gap red shift depends on the films’ phase composition, increasing with the increase of the Urbach energy for increasing rutile content.