Evaluation of microcrack formation of ABNT M2 high speed steel in the EDM process, with addition of silicon carbide powder

Evaluation of microcrack formation of ABNT M2 high speed steel in the EDM process, with addition of silicon carbide powder. It is known that Electrical Discharge Machining (EDM) is a thermal process in which extremely high temperatures (in excess of 1200 degrees C) can occur in the machining area. Consequently, it is easy to understand that during each electric discharge, high temperatures are generated, causing local fusion or even evaporation of the machined material. In each discharge, a crater is formed in the material and a small crater is formed in the electrode. Of every melted material produced in each discharge, only 15% or less is removed using dielectric fluid. The remaining melted material solidifies, forming a wrinkled surface. The characteristics of the obtained surface - overlap of craters, globules of sullage, chimneys, bubbles (formed when the gases arrested are liberated through the resolidified material) - are revealed through an analysis using a scanning electron microscope. The proposed work has as its objective to study the effect of the addition of SiC powder into several dielectric fluids, on microcrack formation of high-speed steel (ABNT M2), during electrical discharge machining. The results show that the samples machined with the addition of SiC powders presented significant reduction in the number of microcracks in the machined surface, when compared with those machined with conventional EDM.30217317

New potential antitumoral fluorescent tetracyclic thieno[3,2-b]pyridine derivatives: interaction with DNA and nanosized liposomes

Fluorescence properties of two new potential antitumoral tetracyclic thieno[3,2-b]pyridine derivatives were studied in solution and in liposomes of DPPC (dipalmitoyl phosphatidylcholine), egg lecithin (phosphatidylcholine from egg yolk; Egg-PC) and DODAB (dioctadecyldimethylammonium bromide). Compound 1, pyrido[2',3':3,2]thieno[4,5-d]pyrido[1,2-a]pyrimidin-6-one, exhibits reasonably high fluorescence quantum yields in all solvents studied (0.20 ≤ ΦF ≤ 0.30), while for compound 2, 3-[(p-methoxyphenyl)ethynyl]pyrido[2',3':3,2]thieno[4,5-d]pyrido[1,2-a]pyrimidin-6-one, the values are much lower (0.01 ≤ ΦF ≤ 0.05). The interaction of these compounds with salmon sperm DNA was studied using spectroscopic methods, allowing the determination of intrinsic binding constants, Ki = (8.7 ± 0.9) × 103 M-1 for compound 1 and Ki = (5.9 ± 0.6) × 103 M-1 for 2, and binding site sizes of n = 11 ± 3 and n = 7 ± 2 base pairs, respectively. Compound 2 is the most intercalative compound in salmon sperm DNA (35%), while for compound 1 only 11% of the molecules are intercalated. Studies of incorporation of both compounds in liposomes of DPPC, Egg-PC and DODAB revealed that compound 2 is mainly located in the hydrophobic region of the lipid bilayer, while compound 1 prefers a hydrated and fluid environment

TRY plant trait database - enhanced coverage and open access

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

TRY plant trait database - enhanced coverage and open access

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Analysis of surface topography in electrical discharge machining of ABNT M2 high speed steel

Analysis of surface topography in electrical discharge machining of ABNT M2 high speed steel. The electrical discharge machining is an exceptional procedure for machining complex shapes into electric conductor materials, mainly for those of high hardness, difficult of machining by traditional processes. At each discharge, a crater is formed in the material and a small crater is formed in the electrode. From every molten material produced in each discharge, only 15%, or less is removed through the dielectric liquid. The remaining of molten material solidifies forming a wrinkled surface. The characteristics of the obtained surface, as overlap of craters, globules of sullage, "chimneys", bubbles (formed when trapped gases are released through the resolidified material), are revealed through an analysis by scanning electron microscopy. The proposed study aimed to examine the effect of several dielectric fluids, on the surface topography and material removal rate, in workpiece of high speed steel (ABNT M2), during the electrical discharge machining.331273