Production of basic potato seed minitubers in substrate and different nitrogen rates

The optimal dose of nitrogen (N) in potato crop depends on the production system. The objective of this study was to determine the optimal dose of N for the production of basic potato seed minitubers and evaluate the effect of N rates on physiological and nitrogen indices in the youngest fully developed leaf (fourth leaf) and in the oldest leaf of the plants at 60 days after planting. The experiment was conducted in a greenhouse at the Departamento de Fitotecnia da Universidade Federal de Viçosa. The treatments consisted of five N rates (0, 45, 90, 180 and 360 mg dm-3), with 10% of each dose applied at planting and the remainder through irrigation water, daily, for 30 days. The nitrogen rates positively influenced the physiological indices (length, width, leaf area, number of leaves, fresh mass and dry mass) and nitrogen (level and content of N and N-NO³ in the dry mass and SPAD) both in the fourth leaf and in the oldest leaf. Likewise, the N rates positively influenced the number and mass of harvested tubers. The largest number (5.44 tubers/plant) and the maximum mass of tubers (243.5 g/plant) were obtained with 360.0 and 332.9 mg N dm-3, respectively. Therefore, the mass and number of tubers were not optimized by the same N rate. The critical SPAD index was 38.8 in the fourth leaf, which was more sensitive to the effect of N rates than the oldest leaf.

Growth and nutrient accumulation in mycorrhized papaya seedlings cultivated in a phosphorus-fertilized substrate

ABSTRACT The indiscriminate use of mineral fertilizers in papaya orchards has increased production costs, and the use of arbuscular mycorrhizal fungi is a promising alternative to reduce such expenses. Therefore, the present research aimed at studying the efficiency of arbuscular mycorrhizal fungi (AMF) on dry matter and nutrient accumulation in Sunrise Solo papaya seedlings, by applying doses of P2O5 (triple superphosphate) that are harmful to the symbiosis. The experiment was carried out in a protected environment and was set up in a randomized block design with four replications, and consisted of four P2O5 doses (0, 672, 1386 and 2100 mg dm-3), three mycorrhizal fungi species (Gigaspora margarita, Entrophospora colombiana and Scutellospora heterogama) and the control treatment (mycorrhiza-free). Shoot and root dry matter as well as nitrogen, phosphorus and potassium contents in leaf and root tissues were assessed. Mycorrhizal inoculation promoted a 30% increase in shoot dry matter in relation to the control treatment. Mycorrhizal fungi promoted increases in leaf and root nitrogen content up to 672 mg dm-3 P2O5. Inoculation of E. colombiana favored the highest gains in root and shoot dry matter. P2O5 fertilization increased foliar and root phosphorus content.

Scaling of the elastic contribution to the surface free energy of a nematic liquid crystal on a sawtoothed substrate

We characterize the elastic contribution to the surface free energy of a nematic liquid crystal in the presence of a sawtooth substrate. Our findings are based on numerical minimization of the Landau-de Gennes model and analytical calculations on the Frank-Oseen theory. The nucleation of disclination lines (characterized by non-half-integer winding numbers) in the wedges and apexes of the substrate induces a leading order proportional to q ln q to the elastic contribution to the surface free-energy density, with q being the wave number associated with the substrate periodicity.

Development of membranes for purification of liquid effluents from stainless steel pickling

Este trabalho foi desenvolvido no âmbito de um projecto europeu intitulado: “Operational demonstration of innovative and sustainable nitrate elimination in stainless steel pickling by higher power biological denitrification technique” Projecto RESP-CT-2007-00047, tendo em vista o desenvolvimento de membranas para o tratamento de efluente resultante da decapagem do aço inox. Numa fase inicial foram desenvolvidas membranas compostas assimétricas pelo método de polimerização interfacial. Estas membranas foram produzidas utilizando uma membrana comercial de suporte em polietersulfona e os filmes selectivos de poliamiada foram formados por reacção entre 1,3,5-tri(clorocarboni)benzeno (TMC) e várias dinaminas: piperazina (PIP), N-(2-aminoetil)-piperazina (EAP), 1,4-bis(3-aminopropil)-piperazina (DAPP), 6-metil-1,3,5 triazina-2,4 diamina (MTC), Isoforodiamina (IPD) e Dietilenetriamina (DET). A elaboração de membranas de TFC (thin film composite) tinha como objectivo a retenção de sais do efluente resultante da decapagem do aço inox. No entanto, chegou-se a conclusão de que o principal problema do efluente não era a retenção dos sais, mas sim a retenção da matéria orgânica. Assim, já não era necessa´ria a produção de membranas compostas, mas apenas uma membrana suporte simples de microfiltração. Numa segunda fase procedeu-se a preparação da membrana suporte pelo método da inversão de fase, tendo-se testado vários tipos de polímeros: PVC (polyvinyl chloride), PEI (Polyetherimide) e um polímero termoplástico geral. A membrana seleccionada foi a de PEI, com base na sua permeabilidade à água destilada e ao efluente resultante das águas residuais da decapagem do aço inox. Todas as membranas elaboradas durante a realização deste trabalho foram testadas na célula de Berghof a uma pressão de 4bar e com agitação. O principal prâmetro estudado foi a permeabilidade da membrana.

New Steel Alloys for the Design of Heat Recovery Steam Generator Components of Combined Cycle Gas Plants

Demand for power is growing every day, mainly due to emerging economies in countries such as China, Russia, India, and Brazil. During the last 50 years steam pressure and temperature in power plants have been continuously raised to improve thermal efficiency. Recent efforts to improve efficiency leads to the development of a new generation of heat recovery steam generator, where the Benson once-through technology is applied to improve the thermal efficiency. The main purpose of this paper is to analyze the mechanical behavior of a high pressure superheater manifold by applying finite element modeling and a finite element analysis with the objective of analyzing stress propagation, leading to the study of damage mechanism, e.g., uniaxial fatigue, uniaxial creep for life prediction. The objective of this paper is also to analyze the mechanical properties of the new high temperature resistant materials in the market such as 2Cr Bainitic steels (T/P23 and T/P24) and also the 9-12Cr Martensitic steels (T/P91, T/P92, E911, and P/T122). For this study the design rules for construction of power boilers to define the geometry of the HPSH manifold were applied.

Substrate interaction with recombinant amidase from Pseudomonas aeruginosa during biocatalysis

The interaction of a variety of substrates with Pseudomonas aeruginosa native amidase (E.C. 3.5.1.4), overproduced in an Escherichia coli strain, was investigated using difference FTIR spectroscopy. The amides used as substrates showed an increase in hydrogen bonding upon association in multimers, which was not seen with esters. Evidence for an overall reduction or weakening of hydrogen bonding while amide and ester substrates are interacting with the enzyme is presented. The results describe a spectroscopic approach for analysis of substrate-amidase interaction and in situ monitoring of the hydrolysis and transferase reaction when amides or esters are used as substrates.

Fabrication of Three-Dimensional Dendritic Ni-Co Films By Electrodeposition on Stainless Steel Substrates

Co-deposition of nickel and cobalt was carried out on austenitic stainless steel (AISI 304) substrates by imposing a square waveform current in the cathodic region. The innovative procedure applied in this work allows creating a stable, fully developed, and open porous three-dimensional (3D) dendritic structure, which can be used as electrode for redox supercapacitors. This study investigates in detail the influence of the applied current density on the morphology, mass, and chemical composition of the deposited Ni-Co films and the resulting 3D porous network dendritic structure. The morphology and the physicochemical composition were studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (W). The electrochemical behavior of the materials was evaluated by cyclic voltammetry (CV). The results highlight the mechanism involved in the coelectrodeposition process and how the lower limit current density tailors the film composition and morphology, as well as its electrochemical activity.

The effect of the angle of incidence on the aqueous corrosion of ion implanted M50 steel substrates

Following work on tantalum and chromium implanted flat M50 steel substrates, this work reports on the electrochemical behaviour of M50 steel implanted with tantalum and chromium and the effect of the angle of incidence. Proposed optimum doses for resistance to chloride attack were based on the interpretation of results obtained during long-term and accelerated electrochemical testing. After dose optimization from the corrosion viewpoint, substrates were implanted at different angles of incidence (15°, 30°, 45°, 60°, 75°, 90°) and their susceptibility to localized corrosion assessed using open-circuit measurements, step by step polarization and cyclic voltammetry at several scan rates (5–50 mV s-1). Results showed, for tantalum implanted samples, an ennoblement of the pitting potential of approximately 0.5 V for an angle of incidence of 90°. A retained dose of 5 × 1016 atoms cm-2 was found by depth profiling with Rutherford backscattering spectrometry. The retained dose decreases rapidly with angle of incidence. The breakdown potential varies roughly linearly with the angle of incidence up to 30° falling fast to reach -0.1 V (vs. a saturated calomel electrode (SCE)) for 15°. Chromium was found to behave differently. Maximum corrosion resistance was found for angles of 45°–60° according to current densities and breakdown potentials. Cr+ depth profiles ((p,γ) resonance broadening method), showed that retained doses up to an angle of 60° did not change much from the implanted dose at 90°, 2 × 1017 Cr atoms cm-2. The retained implantation dose for tantalum and chromium was found to follow a (cos θ)8/3 dependence where θ is the angle between the sample normal and the beam direction.

Invasion success and development of benthic assemblages: effect of timing, duration of submersion and substrate type

Copyright © 2013 Elsevier Ltd. All rights reserved.

Tratamento de superfícies metálicas por nanotecnologia

Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica

Study of vanadium doped ZnO films prepared by dc reactive magnetron sputtering at different substrate temperatures

ZnO films doped with vanadium (ZnO:V) have been prepared by dc reactive magnetron sputtering technique at different substrate temperatures (RT–500 C). The effects of the substrate temperature on ZnO:V films properties have been studied. XRD measurements show that only ZnO polycrystalline structure has been obtained, no V2O5 or VO2 crystal phase can be observed. It has been found that the film prepared at low substrate temperature has a preferred orientation along the (002) direction. As the substrate temperature is increased, the (002) peak intensity decreases. When the substrate temperature reaches the 500 C, the film shows a random orientation. SEM measurements show a clear formation of the nano-grains in the sample surface when the substrate temperature is higher than 400 C. The optical properties of the films have been studied by measuring the specular transmittance. The refractive index has been calculated by fitting the transmittance spectra using OJL model combined with harmonic oscillator.

Lightweight amorphous silicon photovoltaic modules on flexible plastic substrate

Solar cells on lightweight and flexible substrates have advantages over glass-or wafer-based photovoltaic devices in both terrestrial and space applications. Here, we report on development of amorphous silicon thin film photovoltaic modules fabricated at maximum deposition temperature of 150 degrees C on 100 mu m thick polyethylene-naphtalate plastic films. Each module of 10 cm x 10 cm area consists of 72 a-Si:H n-i-p rectangular structures with transparent conducting oxide top electrodes with Al fingers and metal back electrodes deposited through the shadow masks. Individual structures are connected in series forming eight rows with connection ports provided for external blocking diodes. The design optimization and device performance analysis are performed using a developed SPICE model.

Microstructure, mechanical properties and chemical degradation of brazed AISI 316 stainless steel/alumina systems

The main aims of the present study are simultaneously to relate the brazing parameters with: (i) the correspondent interfacial microstructure, (ii) the resultant mechanical properties and (iii) the electrochemical degradation behaviour of AISI 316 stainless steel/alumina brazed joints. Filler metals on such as Ag–26.5Cu–3Ti and Ag–34.5Cu–1.5Ti were used to produce the joints. Three different brazing temperatures (850, 900 and 950 °C), keeping a constant holding time of 20 min, were tested. The objective was to understand the influence of the brazing temperature on the final microstructure and properties of the joints. The mechanical properties of the metal/ceramic (M/C) joints were assessed from bond strength tests carried out using a shear solicitation loading scheme. The fracture surfaces were studied both morphologically and structurally using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). The degradation behaviour of the M/C joints was assessed by means of electrochemical techniques. It was found that using a Ag–26.5Cu–3Ti brazing alloy and a brazing temperature of 850 °C, produces the best results in terms of bond strength, 234 ± 18 MPa. The mechanical properties obtained could be explained on the basis of the different compounds identified on the fracture surfaces by XRD. On the other hand, the use of the Ag–34.5Cu–1.5Ti brazing alloy and a brazing temperature of 850 °C produces the best results in terms of corrosion rates (lower corrosion current density), 0.76 ± 0.21 μA cm−2. Nevertheless, the joints produced at 850 °C using a Ag–26.5Cu–3Ti brazing alloy present the best compromise between mechanical properties and degradation behaviour, 234 ± 18 MPa and 1.26 ± 0.58 μA cm−2, respectively. The role of Ti diffusion is fundamental in terms of the final value achieved for the M/C bond strength. On the contrary, the Ag and Cu distribution along the brazed interface seem to play the most relevant role in the metal/ceramic joints electrochemical performance.

Scheduling a cutting and treatment stainless steel sheet line with self-management capabilities

With advancement in computer science and information technology, computing systems are becoming increasingly more complex with an increasing number of heterogeneous components. They are thus becoming more difficult to monitor, manage, and maintain. This process has been well known as labor intensive and error prone. In addition, traditional approaches for system management are difficult to keep up with the rapidly changing environments. There is a need for automatic and efficient approaches to monitor and manage complex computing systems. In this paper, we propose an innovative framework for scheduling system management by combining Autonomic Computing (AC) paradigm, Multi-Agent Systems (MAS) and Nature Inspired Optimization Techniques (NIT). Additionally, we consider the resolution of realistic problems. The scheduling of a Cutting and Treatment Stainless Steel Sheet Line will be evaluated. Results show that proposed approach has advantages when compared with other scheduling systems

The effect of metal transfer modes and shielding gas composition on the emission of ultraafine particles in MAG steel welding

The present study aims to characterize ultrafine particles emitted during gas metal arc welding of mild steel and stainless steel, using different shielding gas mixtures, and to evaluate the effect of metal transfer modes, controlled by both processing parameters and shielding gas composition, on the quantity and morphology of the ultrafine particles. It was found that the amount of emitted ultrafine particles (measured by particle number and alveolar deposited surface area) are clearly dependent from the main welding parameters, namely the current intensity and the heat input of the Welding process. The emission of airborne ultrafine particles increases with the current intensity as fume formation rate does. When comparing the shielding gas mixtures, higher emissions were observed for more oxidizing mixtures, that is, with higher CO2 content, which means that these mixtures originate higher concentrations of ultrafine particles (as measured by number of particles. by cubic centimeter of air) and higher values of alveolar deposited surface area of particles, thus resulting in a more hazardous condition regarding welders exposure.