555 research outputs found

    An efficient method for DNA extraction from Cladosporioid fungi

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    We developed an efficient method for DNA extraction from Cladosporioid fungi, which are important fungal plant pathogens. The cell wall of Cladosporioid fungi is often melanized, which makes it difficult to extract DNA from their cells. In order to overcome this we grew these fungi for three days on agar plates and extracted DNA from mycelium mats after manual or electric homogenization. High-quality DNA was isolated, with an A260/A280 ratio ranging between 1.6 and 2.0. Isolated genomic DNA was efficiently digested with restriction enzymes and produced distinct banding patterns on agarose gels for the different Cladosporium species. Clear DNA fragments from the isolated DNA were amplified by PCR using small and large subunit rDNA primers, demonstrating that this method provides DNA of sufficiently high quality for molecular analyse

    SPH and FEM Investigation of Hydrodynamic Impact Problems

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    Simulation of hydrodynamic impact problems and its effect on surrounding structures, can be considered as a fluid structure coupling problem. The application is mainly used in automotive and aerospace engineering and also in civil engineering. Classical FEM and Finite Volume methods were the main formulations used by engineers to solve these problems. For the last decades, new formulations have been developed for fluid structure coupling applications using mesh free methods as SPH method, (Smooth Particle Hydrodynamic) and DEM (Discrete Element Method). Up to these days very little has been done to compare different methods and assess which one would be more suitable. In this paper the mathematical and numerical implementation of the FEM and SPH formulations for hydrodynamic problem are described. From different simulations, it has been observed that for the SPH method to provide similar results as FEM Lagrangian formulations, the SPH meshing, or SPH particle spacing needs to be finer than FEM mesh. To validate the statement, we perform a simulation of a hydrodynamic impact on an elasto-plastic plate structure. For this simple, the particle spacing of SPH method needs to be at least two times finer than FEM mesh. A contact algorithm is performed at the fluid structure interface for both SPH and FEM formulations. In the paper the efficiency and usefulness of two methods, often used in numerical simulations, are compared

    Load-Displacement Curves of Spot Welded, Bonded, and Weld-Bonded Joints for Dissimilar Materials and Thickness

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    Three-dimensional finite element models of spot welded, bonded and weld-bonded joints are developed using ABAQUS software. Each model consists of two strips with dissimilar materials and thickness and is subjected to an axial loading. The bonded and weld-bonded joints have specific adhesive thickness. A detailed experimental plan to define many properties and quantities such as, the elastic - plastic properties, modulus of elasticity, fracture limit, and properties of the nugget and heat affected zones are carried out. Experiments include standard testing of the base metal, the adhesive, the nugget and heat affected zone. They also include employing the indentation techniques, and ductile fracture limits criteria, using the special notch tests. Complete load-displacement curves are obtained for all joining models and a comparison is made to determine the best combination

    Bromelain capped gold nanoparticles as the novel drug delivery carriers to aggrandize effect of the antibiotic levofloxacin

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    To develop bromelain capped gold nanoparticles (BRN capped Au-NPs) as the effective drug delivery carriers of the antibiotic levofloxacin (LvN) and evaluate antibacterial potential of its bioconjugated form compared to pure LvN. BRN capped Au-NPs were synthesized by in vitro method and bioconjugated to LvN using 1-ethyl-3-(3-dimethylamino-propyl)-carbodiimide as activator to form Au-BRN-LvN-NPs. These were characterized for mean particle size by dynamic light scattering analysis, zeta potential by Zetasizer nanosystem analysis and transmission electron microscopy (TEM) on carbon coated TEM copper grids by TEM respectively. Drug loading efficiency of LvN was calculated using UV-visible spectroscopy by standard curve of pure LvN. Antibacterial efficacy of Au-BRN-LvN-NPs and pure LvN was determined by evaluating minimum inhibitory concentration (MIC) against Staphylococcus aureus and Eschereschia coli.Two peaks were observed in Au-BRN-LvNNPs spectrum one at 307 nm and other at 526 nm while one peak in BRN capped Au-NPs at 522 nm during UV spectroscopy suggesting red shift. The drug loading efficiency of LvN was found to be 84.8 ± 2.41 %. The diameter of Au-BRN-LvN-NPs and BRN capped Au-NPs were found to be (58.65 ± 2 nm, 38.11 ± 2 nm), zeta potential (-9.01 mV, -13.8 mV) and surface morphology (~13.2 nm, 11.4 nm) respectively. The MICs against S. aureus and E. coli were found to be (0.128 μg/mL, 1.10 μg/mL) for Au-BRN-LvN-NPs and (0.547 μg/mL, 1.96μg/mL) for pure LvN. The results suggested that BRN capped Au-NPs can be used as effective drug delivery carriers of the antibiotic LvN. The Au-BRN-LvN-NPs exhibited enhanced antibacterial activity compared to pure LvN alone

    Experimental and Numerical Investigation for Membrane Deployment using SPH and ALE Formulations

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    Simulation of airbag and membrane deployment under pressurized gas problems becomes more and more the focus of computational engineering, where FEM (Finite element Methods) for structural mechanics and Finite Volume for CFD are dominant. New formulations have been developed for FSI applications using mesh free methods as SPH method, (Smooth Particle Hydrodynamic). Up to these days very little has been done to compare different methods and assess which one would be more suitable. For small deformation, FEM Lagrangian formulation can solve structure interface and material boundary accurately, the main limitation of the formulation is high mesh distortion for large deformation and moving structure. One of the commonly used approach to solve these problems is the ALE formulation which has been used with success in the simulation of FSI (Fluid Structure Interaction) with large structure motion such as sloshing fuel tank in automotive industry and bird impact in aeronautic industry. For some applications, including bird impact and high velocity impact problems, engineers have switched from ALE to SPH method to reduce CPU time and save memory allocation. In this paper the mathematical and numerical implementation of the ALE and SPH formulations are described. From different simulation, it has been observed that for the SPH method to provide similar results as ALE or Lagrangian formulations, the SPH meshing, or SPH spacing particles needs to be finer than the ALE mesh. To validate the statement, we perform a simulation of membrane deployment generated by high pressurized gas. For this simple problem, the particle spacing of SPH method needs to be at least two times finer than ALE mesh. A contact algorithm is performed at the FSI for both SPH and ALE formulations

    Deployment of a Neo-Hookean membrane: experimental and numerical analysis

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    The aim of this research is to assess the response of a thin membrane subjected to high-pressure gas loading for inflation. This procedure is applied during the design process of the membrane structure to allow the product to resist high-pressure loading and to further characterize the hyper-elastic material. The simulation in this work considers the standard procedures used in the LS-DYNA software, which applies such assumptions as a uniform airbag pressure and temperature in addition to a more recently developed procedure that takes into account the fluid-structure interaction between the inflation gas source and the hyper-elastic membrane; this approach is referred to as the Arbitrary Lagrangian Eulerian (ALE) formulation. Until recently, to simulate the inflation of the hyperelastic membrane, a uniform pressure based on a thermodynamic model or experimental test has been applied to the structure as the boundary conditions. To conserve CPU time, this work combines both methods; the fluid structure coupling method is used at an earlier stage in which the fluid is modeled using full hydrodynamic equations, and at the later stage, the uniform pressure procedure is applied, and the fluid mesh and analysis are removed from the computation. Both simulations were compared to test data, indicating satisfactory correlation with the more recently developed procedure, the ALE theory, which showed the greatest accuracy both in terms of graphical and schematic comparison, particularly in the early stages of the inflation process. As a result, the new simulation procedure model can be applied to research on the effects of design changes in the new membrane

    Fluid solid interaction simulation of CFRP shell structure

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    Accepted manuscript version. Published version available at http://nonlinearstudies.com/index.php/mesa/article/view/1532.This work attempts to model the dynamic behavior of Carbon Fiber Reinforced Polymer (CFRP) shell structure subjected to water shock wave to improve the results presented in the study by Khawaja et al., 2014. In the previous study, the real physical problem was simplified by decoupling the fluid and the structural phenomena, applying the recorded experimental fluid pressure load to the CFRP shell structure. The current study involves not only structure modeling, as given in the earlier study, but also fluid behavior using the Arbitrary Lagrangian-Eulerian (ALE) method. The focus of this study is to highlight the difference in structural response between uncoupled and coupled Fluid Structure Interaction (FSI) numerical solution, and also to validate the ability of the FSI numerical simulation to solve complex problems, involving the generation and the propagation of water shock waves and their impact on the composite shell structures, using both multi-material ALE (MM-ALE) methods and advanced non-linear Fluid Structure Interaction (FSI) strong coupling algorithms. Results obtained from experiments are compared with numerical simulations using the LS-DYNA (R) software. The results are found to be in good agreement with the experimental data and are improved by considering the coupling effects, as the mass of the water acts as a viscous damper and reduces the high-frequency oscillations in the structural response

    Ευρετικές προσεγγίσεις του μοναδιάστατου προβλήματος πακετοποίησης

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    Article 59.1, of the International Code of Nomenclature for Algae, Fungi, and Plants (ICN; Melbourne Code), which addresses the nomenclature of pleomorphic fungi, became effective from 30 July 2011. Since that date, each fungal species can have one nomenclaturally correct name in a particular classification. All other previously used names for this species will be considered as synonyms. The older generic epithet takes priority over the younger name. Any widely used younger names proposed for use, must comply with Art. 57.2 and their usage should be approved by the Nomenclature Committee for Fungi (NCF). In this paper, we list all genera currently accepted by us in Dothideomycetes (belonging to 23 orders and 110 families), including pleomorphic and non-pleomorphic genera. In the case of pleomorphic genera, we follow the rulings of the current ICN and propose single generic names for future usage. The taxonomic placements of 1261 genera are listed as an outline. Protected names and suppressed names for 34 pleomorphic genera are listed separately. Notes and justifications are provided for possible proposed names after the list of genera. Notes are also provided on recent advances in our understanding of asexual and sexual morph linkages in Dothideomycetes. A phylogenetic tree based on four gene analyses supported 23 orders and 75 families, while 35 families still lack molecular data

    Effect of Milling Strategy on the Surface Quality of AISI P20 Mold Steel

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    This paper explores the impact of various milling strategies, including up-milling, down-milling, and hybrid approaches, on the surface roughness of AISI P20 mold steel. The study is methodically divided into three stages to comprehensively understand the effects of these strategies. The first stage involves milling single slots with varying cutting parameters to establish baseline effects. The second stage examines the effects of consistent milling strategies (up-up and down-down) on surface quality. The third stage probes into hybrid strategies (up-down and down-up) to assess their effectiveness. Central to this investigation is not only the type of milling strategy but also how cutting speed and feed rate influence the resultant surface roughness. Our findings indicate that up-milling generally leads to a 22% increase in surface roughness compared to down-milling. This trend is visually verified by surface texture analyses. When comparing consistent strategies, up-up milling tends to produce rougher surfaces than down-down milling by approximately 25%, characterized by distinctive scratches and feed mark overlays. Remarkably, while the hybrid milling strategies do not exhibit significant differences in surface roughness, variations in cutting speed and feed rate play a crucial role. Specifically, at lower speeds, hybrid milling achieves smoother surfaces than the identical double milling mode, while at a cutting speed of 100 m/min, the double mode demonstrates a notable decrease in roughness. Additionally, this study introduces a color mapping simulation for machined pockets, validated by experimental results, to predict surface roughness based on the strategic history of milling, thereby offering valuable insights for optimizing milling processes

    Chrysin‐Loaded Chitosan Nanoparticles Potentiates Antibiofilm Activity against \u3cem\u3eStaphylococcus aureus\u3c/em\u3e

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    The application of nanotechnology in medicine is gaining popularity due to its ability to increase the bioavailability and biosorption of numerous drugs. Chrysin, a flavone constituent of Orocylumineicum vent is well‐reported for its biological properties. However, its therapeutic potential has not been fully exploited due to its poor solubility and bioavailability. In the present study, chrysin was encapsulated into chitosan nanoparticles using TPP as a linker. The nanoparticles were characterized and investigated for their anti‐biofilm activity against Staphylococcus aureus. At sub‐Minimum Inhibitory Concentration, the nanoparticles exhibited enhanced anti‐biofilm efficacy against S. aureus as compared to its bulk counterparts, chrysin and chitosan. The decrease in the cell surface hydrophobicity and exopolysaccharide production indicated the inhibitory effect of the nanoparticles on the initial stages of biofilm development. The growth curve analysis revealed that at a sub‐MIC, the nanoparticles did not exert a bactericidal effect against S. aureus. The findings indicated the anti‐biofilm activity of the chrysin‐loaded chitosan nanoparticles and their potential application in combating infections associated with S. aureus
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