Search results for: initial strain

Authors: Sonia Sassi, Mostapha Tarfaoui, Hamza Ben Yahia

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In this investigation, an experimental technique in which the dynamic response, damage kinetic and heat dissipation are measured simultaneously during high strain rates on adhesively bonded joints materials. The material used in this study is widely used in the design of structures for military applications. It was composed of a 45° Bi-axial fiber-glass mat of 0.286 mm thickness in a Polyester resin matrix. In adhesive bonding, a NORPOL Polyvinylester of 1 mm thickness was used to assemble the composite substrate. The experimental setup consists of a compression Split Hopkinson Pressure Bar (SHPB), a high-speed infrared camera and a high-speed Fastcam rapid camera. For the dynamic compression tests, 13 mm x 13 mm x 9 mm samples for out-of-plane tests were considered from 372 to 1030 s-1. Specimen surface is controlled and monitored in situ and in real time using the high-speed camera which acquires the damage progressive in specimens and with the infrared camera which provides thermal images in time sequence. Preliminary compressive stress-strain vs. strain rates data obtained show that the dynamic material strength increases with increasing strain rates. Damage investigations have revealed that the failure mainly occurred in the adhesive/adherent interface because of the brittle nature of the polymeric adhesive. Results have shown the dependency of the dynamic parameters on strain rates. Significant temperature rise was observed in dynamic compression tests. Experimental results show that the temperature change depending on the strain rate and the damage mode and their maximum exceed 100 °C. The dependence of these results on strain rate indicates that there exists a strong correlation between damage rate sensitivity and heat dissipation, which might be useful when developing damage models under dynamic loading tacking into account the effect of the energy balance of adhesively bonded joints.

Keywords: adhesive bonded joints, Hopkinson bars, out-of-plane tests, dynamic compression properties, damage mechanisms, heat dissipation

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Authors: Xing Ping Hu, Yuexun Tian, Jerome Hogsette

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Housefly, Musca domestica L., is a serious urban nuisance and public health/food safety concern. This study evaluated the topical toxicity of 17 essential oil components and 3 plant essential oils against permethrin-resistant adult females and insecticide-susceptible house fly strains. Results show that thymol had the lowest LD₅₀ values against permethrin-resistant strain (43.77 and 41.10 ug per fly) and permethrin-susceptible strain (35.19 and 29.16 ug per fly) at both 24- and 48-hours post treatments; (+)-Pulegone had the lowest LD₉₅ values against the permethrin-resistant strain (0.15 and 0.10 mg per fly) at 24- and 48-hours post treatments, whereas plant thyme oil had the lowest LD₉₅ value of 0.17 mg per fly at post-24h and post-48h against the permethrin-susceptible strain. Additionally, the LD₅₀s was slightly but not significantly negatively correlated with the boiling points of the compounds tested; but showed no correlation with the density and LogP. These results indicate that specific essential oils and compounds have topical insecticidal properties against house flies with low dose. They may have the potential for development as botanical insecticides.

Keywords: urban pest, public health, pest management, botanical chemical

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Authors: Momita Das, Sofia Banu, Jibon Kotoky

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Environmental contamination of natural resources with persistent organic pollutants is of great world-wide apprehension. Polycyclic aromatic hydrocarbons (PAHs) are among the organic pollutants, released due to various anthropogenic activities. Due to their toxic, carcinogenic and mutagenic properties, PAHs are of environmental and human concern. Presently, bioremediation has evolved as the most promising biotechnology for cleanup of such contaminants because of its economical and less cost effectiveness. In the present study, distribution of 16 USEPA priority PAHs was determined in the soil samples collected from fifteen different sites of Guwahati City, the Gateway of the North East Region of India. The total concentrations of 16 PAHs (Σ16 PAHs) ranged from 42.7-742.3 µg/g. Higher concentration of total PAHs was found more in the Industrial areas compared to all the sites (742.3 µg/g and 628 µg/g). It is noted that among all the PAHs, Naphthalene, Acenaphthylene, Anthracene, Fluoranthene, Chrysene and Benzo(a)Pyrene were the most available and contain the higher concentration of all the PAHs. Since microbial activity has been deemed the most influential and significant cause of PAH removal; further, twenty-three bacteria were isolated from the most contaminated sites using the enrichment process. These strains were acclimatized to utilize naphthalene and anthracene, each at 100 µg/g concentration as sole carbon source. Among them, one Gram-positive strain (JMG-01) was selected, and biodegradation ability and initial catabolic genes of PAHs degradation were investigated. Based on 16S rDNA analysis, the isolate was identified as Bacillus cereus strain JMG-01. Topographic images obtained using Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) at scheduled time intervals of 7, 14 and 21 days, determined the variation in cell morphology during the period of degradation. AFM and SEM micrograph of biomass showed high filamentous growth leading to aggregation of cells in the form of biofilm with reference to the incubation period. The percentage degradation analysis using gas chromatography and mass analyses (GC-MS) suggested that more than 95% of the PAHs degraded when the concentration was at 500 µg/g. Naphthalene, naphthalene-2-methy, benzaldehyde-4-propyl, 1, 2, benzene di-carboxylic acid and benzene acetic acid were the major metabolites produced after degradation. Moreover, PCR experiments with specific primers for catabolic genes, ndo B and Cat A suggested that JMG-01 possess genes for PAHs degradation. Thus, the study concludes that Bacillus cereus strain JMG-01 has efficient biodegrading ability and can trigger the clean-up of PAHs contaminated soil.

Keywords: AFM, Bacillus cereus strain JMG-01, degradation, polycyclic aromatic hydrocarbon, SEM

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Authors: Subodh Nath Patel, Raja Raman, Mananshi Adhikary, Jitendra Mathur, Sandip Bhattacharyya

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The composition adjustment by sealed argon bubbling–oxygen blowing (CAS-OB) process is a process designed for adjusting steel composition and temperature during secondary metallurgy. One of the equipment in the said process is a snorkel or bell, fixed to a movable bracket. Snorkel serves the purpose of feeding ferroalloys into the liquid metal simultaneously removing gases to the gas cleaning system through its port at its top. The bell-shaped snorkel consists of two parts. The upper part has an inside liner, and the lower part is lined on both side with high-alumina castable reinforced with 2% stainless steel needles. Both the parts are coupled with a flange bolt system. These flanges were found to get buckled during operation, and the gap was generating between them. This problem was chronic since its. It was expected to give a life of 80 heats, but it was failing within 45-50 heats. After every 25-30 heats, it had to be repaired by changing and/or tightening its nuts and bolts. Visual observation, microstructural analysis through optical microscopes and SEM, hardness measurement and thermal strain calculation were carried out to find out the root cause of this problem. The calculated thermal strain was compared with actual thermal strain; comparison of the two revealed that thermal strain was responsible for buckling. Finite element analysis (FEA) was carried out to reaffirm the effect temperature on the flanges. FEA was also used in the modification in the design of snorkel flange to accommodate thermal strain. Thermal insulation was also recommended which increased its life from 45 heats to 65 heats, impacting business process positively.

Keywords: CAS OB process, finite element analysis, snorkel, thermal strain

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Authors: Prashant Motwani, Arghadeep Laskar

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The transfer of prestress force from prestressing strands to the surrounding concrete is dependent on the bond between the two materials. It is essential to understand the actual bond stress distribution along the transfer length to determine the transfer zone in pre-tensioned concrete. A 3-D nonlinear finite element model has been developed to simulate the transfer of prestress force from steel to concrete in pre-tensioned bridge girders through thermal strain technique using commercially available package ABAQUS. Full-scale bridge girder has been analyzed with thermal strain approach where the damage plasticity constitutive model has been used to model concrete. Parameters such as concrete strain, effective prestress, upward camber and longitudinal stress have been compared with analytical results. The discrepancy between numerical and analytical values was within 20%. The paper also presents a convergence study on mesh density and aspect ratio of the elements to perform the finite element study.

Keywords: aspect ratio, bridge girder, centre of gravity of strand, mesh density, finite element model, pretensioned bridge girder

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Authors: Kashif Ahmed

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Recent years researchers have been motivated towards extensive exploring of living organism, which could be utilized effectively in intense industrial conditions. The present study shows enhanced production, purification and characterization of industrial enzyme, invertase (Beta-D-fructofuranosidase) from Penicillium lilacinum. Various agricultural based by-products (cotton stalk, sunflower waste, rice husk, molasses and date syrup) were used as energy source. The highest amount of enzyme (13.05 Units/mL) was produced when the strain was cultured on growth medium containing date syrup as energy source. Yeast extract was used as nitrogen source after 96 h of incubation at incubation temperature of 40º C. Initial pH of medium was 8.0, inoculum size 6x10⁶ conidia and 200 rev/min agitation rate. The enzyme was also purified (7 folds than crude) and characterized. Molecular mass of purified enzyme (65 kDa) was determined by 10 % SDS-PAGE. Lineweaver-Burk Plot was used to determine Kinetic constants (Vmax 178.6 U/mL/min and Km 2.76 mM). Temperature and pH optima were 55º C and 5.5 respectively. MnCl₂ (52.9 %), MgSO₄ (48.9 %), BaCl₂ (24.6 %), MgCl₂ (9.6 %), CoCl₂ (5.7 %) and NaCl (4.2 %) enhanced the relative activity of enzyme and HgCl₂ (-92.8 %), CuSO₄ (-80.2 %) and CuCl₂ (-76.6 %) were proved inhibitors. The strain was showing enzyme activity even at extreme conditions of temperature (up to 60º C) and pH (up to 9), so it can be used in industries.

Keywords: invertase, Penicillium lilacinum, submerged fermentation, industrial enzyme

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Authors: Ahmad Idi

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The biosynthesis and properties of polyhydroxyalkanoate (PHA) are determined by the bacterial strain and the culture condition. Hence this study elucidates the structure and properties of PHA produced by a newly isolated strain of photosynthetic bacterium, Rhodobacter sphaeroides ADZ101 grown under the optimized culture condition. The properties of the accumulated PHA were determined via FTIR, NMR, TGA, and GCMS analyses. The results showed that acetate and ammonia chloride had the highest PHA accumulation with a ratio of 32.5 mM at neutral pH. The structural analyses showed that the polymer comprises both short and medium-chain length monomers ranging from C5, C13, C14, and C18, as well as the presence of novel PHA monomers. The thermal analysis revealed that the maximum temperature of decomposition occurred at 395°C and 454°C, indicating two major decomposition reactions. Thus this bacterial strain, optimized culture condition, and the abundance of novel monomers enhanced the thermostability of the accumulated PHA.

Keywords: bioplastic polyhydroxyalkanoates Rhodobacter sphaeroides ADZ101 thermostable PHA

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Authors: Aboussalih Amira, Zarza Tahar, Fedaoui Kamel, Hammoudi Saleh

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This work focuses on the simulation of the prediction of the behaviour of austenitic stainless steel (SS) 304L under complex loading in stress and imposed strain. The Chaboche model is a cable to describe the response of the material by the combination of two isotropic and nonlinear kinematic work hardening, the model is implemented in the ZébuLon computer code. First, we represent the evolution of the axial stress as a function of the plastic strain through hysteresis loops revealing a hardening behaviour caused by the increase in stress by stress in the direction of tension/compression. In a second step, the study of the ratcheting phenomenon takes a key place in this work by the appearance of the average stress. In addition to the solicitation of the material in the biaxial direction in traction / torsion.

Keywords: damage, 304L, Ratcheting, plastic strain

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Authors: A. Hocine, A. Ghouaoula, S. M. Medjdoub, M. Cherifi

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The present paper proposed a meso–macro model describing the mechanical behaviour composite laminates of staking sequence [+θ/-θ]s under tensil loading. The behaviour of a layer is ex-pressed through elasticity coupled to damage. The elastic strain is due to the elasticity of the layer and can be modeled by using the classical laminate theory, and the laminate is considered as an orthotropic material. This means that no coupling effect between strain and curvature is considered. In the present work, the damage is associated to cracking of the matrix and parallel to the fibers and it being taken into account by the changes in the stiffness of the layers. The anisotropic damage is completely described by a single scalar variable and its evolution law is specified from the principle of maximum dissipation. The stress/strain relationship is investigated in plane stress loading.

Keywords: damage, behavior modeling, meso-macro model, composite laminate, membrane loading

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Authors: Alexander P. Vazhenin, Mikhail M. Lavrentiev, Alexey A. Romanenko, Pavel V. Tatarintsev

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One of the problems obstructing effective tsunami modelling is the lack of information about initial wave shape at source. The existing methods; geological, sea radars, satellite images, contain an important part of uncertainty. Therefore, direct measurement of tsunami waves obtained at the deep water bottom peruse recorders is also used. In this paper we propose a new method to reconstruct the initial sea surface displacement at tsunami source by the measured signal (marigram) approximation with the help of linear combination of synthetic marigrams from the selected set of unit sources, calculated in advance. This method has demonstrated good precision and very high performance. The mathematical model and results of numerical tests are here described.

Keywords: numerical tests, orthogonal decomposition, Tsunami Initial Sea Surface Displacement

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Authors: Jakub Bartus, Jaroslav Odrobinak

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In general, composite steel and concrete structures present an effective structural solution utilizing the full potential of both materials. As they have numerous advantages on the construction side, they can greatly reduce the overall cost of construction, which has been the main objective of the last decade, highlighted by the current economic and social crisis. The study represents not only an analysis of composite beams’ behavior having web openings but emphasizes the influence of these openings on the total strain distribution at the level of the steel bottom flange as well. The major investigation was focused on a change in structural performance with respect to various layouts of openings. Examining this structural modification, an improvement of load carrying capacity of composite beams was a prime objective. The study is divided into analytical and numerical parts. The analytical part served as an initial step into the design process of composite beam samples, in which optimal dimensions and specific levels of utilization in individual stress states were taken into account. The numerical part covered the discretization of the preset structural issue in the form of a finite element (FE) model using beam and shell elements accounting for material non–linearities. As an outcome, several conclusions were drawn describing and explaining the effect of web opening presence on the structural performance of composite beams.

Keywords: beam, steel flange, total strain, web opening

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Authors: Wang Jianguo, Ding Xiao, Liu Dong, Wang Haiping, Yang Yanhui, Hu Yang

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The hot deformation behavior of Inconel 718 alloy was studied by uniaxial compression tests under the deformation temperature of 940~1040℃ and strain rate of 0.001-10s⁻¹. The double cone compression (DCC) tests develop strains range from 30% to the 79% strain including all intermediate values of stains at different temperature (960~1040℃). DCC tests were simulated by finite element software which shown the strain and strain rates distribution. The result shows that the peak stress level of the alloy decreased with increasing deformation temperature and decreasing strain rate, which could be characterized by a Zener-Hollomon parameter in the hyperbolic-sine equation. The characterization method of hot processing window containing recrystallization volume fraction and average grain size was proposed for double cone compression test of uniform coarse grain, mixed crystal and uniform fine grain double conical specimen in hydraulic press and screw press. The results show that uniform microstructures can be obtained by low temperature with high deformation followed by high temperature with small deformation on the hydraulic press and low temperature, medium deformation, multi-pass on the screw press. The two methods were applied in industrial forgings process, and the forgings with uniform microstructure were obtained successfully.

Keywords: inconel 718 superalloy, hot processing windows, double cone compression, uniform microstructure

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Authors: Michael Dare Asemoloye, Segun Gbolagade Jonathan, Rafiq Ahmad, Odunayo Joseph Olawuyi, D. O. Adejoye

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Fungi have potentials for degrading hydrocarbons through the secretion of different enzymes. Crude oil tolerance and degradation by Trichoderma harzianum was investigated in this study with its ability to produce peroxidase enzymes (LiP and MnP). Many fungal strains were isolated from rhizosphere of grasses growing on a crude oil spilled site, and the most frequent strain based on percentage incidence was further characterized using morphological and molecular characteristics. Molecular characterization was done through the amplification of Ribosomal-RNA regions of 18s (1609-1627) and 28s (287-266) using ITS1 and ITS4 combinations and it was identified using NCBI BLAST tool. The selected fungus was also subjected to an in-vitro tolerance test at crude oil concentrations of 5, 10, 15, 20 and 25% while 0% served as control. In addition, lignin peroxidase genes (lig1-6) and manganese peroxidase gene (mnp) were detected and expressed in this strain using RT-PCR technique, its peroxidase producing activities was also studied in aliquots (U/ml). This strain had highest incidence of 80%, it was registered in NCBI as Trichoderma harzianum asemoJ KY488466. The strain KY488466 responded to crude oil concentrations as it increase, the dose inhibition response percentage (DIRP) increased from 41.67 to 95.41 at 5 to 25 % crude oil concentrations. All the peroxidase genes are present in KY488466, and expressed with amplified 900-1000 bp through RT-PCR technique. In this strain, lig2, lig4 and mnp genes were over-expressed, lig 6 was moderately expressed, while none of the genes was under-expressed. The strain also produced 90±0.87 U/ml lignin peroxidase and 120±1.23 U/mil manganese peroxidase enzymes in aliquots. These results imply that KY488466 can tolerate and survive high crude oil concentration and could be exploited for bioremediation of oil-spilled soils, the produced peroxidase enzymes could also be exploited for other biotechnological experiments.

Keywords: crude oil, enzymes, expression, peroxidase genes, tolerance, Trichoderma harzianum

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Authors: Suman Paik, P. V. Durgaprasad, Bijan K. Dutta

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A study combining experimental and numerical investigation on the deformation behaviour of single crystals of copper is presented in this paper. Cylindrical samples were cut in specific orientations from high purity copper single crystal and subjected to uniaxial compression loading at quasi-static strain rate. The stress-strain curves along two different crystallographic orientations were then extracted. In order to study and compare the deformation responses, a single crystal plasticity model incorporating non-Schmid effects was developed assuming cross-slip plays an important role in orientation of the material. By making use of crystal plasticity finite element method, the model was applied to investigate the orientation dependence of the stress-strain behaviour of two crystallographic orientations. Finally, details of slip activities of deformed crystals were investigated by linking the orientation of slip lines with the theoretical traces of possible crystallographic planes. The experimentally determined active slip modes were matched with those determined by simulations.

Keywords: crystal plasticity, modelling, non-Schmid effects, finite elements, finite strain

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Authors: K. Khelil, H. Ammar, K. Saouchi

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Fiber Bragg Grating (FBG) structure is an periodically modulated optical fiber. It acts as a selective filter of wavelength whose reflected peak is called Bragg wavelength and it depends on the period of the fiber and the refractive index. The simulation of FBG is based on solving the Coupled Mode Theory equation by using the Transfer Matrix Method which is carried out using MATLAB. It is found that spectral reflectivity is shifted when the change of temperature and strain is uniform. Under non-uniform temperature or strain perturbation, the spectrum is both shifted and destroyed. In case of transverse loading, reflectivity spectrum is split into two peaks, the first is specific to X axis, and the second belongs to Y axis. FBGs are used in civil engineering to detect perturbations applied to buildings.

Keywords: Bragg wavelength, coupled mode theory, optical fiber, temperature measurement

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Authors: William Fuentes, Melany Gil

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Numerical simulations of offshore wind turbines (OWTs) in shallow waters demand sophisticated models considering the cyclic nature of the environmental loads. For the case of an OWT founded on sands, rapid loading may cause a reduction of the effective stress of the soil surrounding the structure. This eventually leads to its settlement, tilting, or other issues affecting its serviceability. In this work, a 3D FE model of an OWT founded on sand is constructed and analyzed. Cyclic loading with different histories is applied at certain points of the tower to simulate some environmental forces. The mechanical behavior of the soil is simulated through the recently proposed ISA-hypoplastic model for sands. The Intergranular Strain Anisotropy ISA can be interpreted as an enhancement of the intergranular strain theory, often used to extend hypoplastic formulations for the simulation of cyclic loading. In contrast to previous formulations, the proposed constitutive model introduces an elastic range for small strain amplitudes, includes the cyclic mobility effect and is able to capture the cyclic behavior of sands under a larger number of cycles. The model performance is carefully evaluated on the FE dynamic analysis of the OWT.

Keywords: offshore wind turbine, monopile, ISA, hypoplasticity

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Authors: Sifeddine Abderrahmani, Sonia Bouafia

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The finite element method is the most practical tool for the analysis of structures, whatever the geometrical shape and behavior. It is extensively used in many high-tech industries, such as civil or military engineering, for the modeling of bridges, motor bodies, fuselages, and airplane wings. Additionally, experience demonstrates that engineers like modeling their structures using the most basic finite elements. Numerous models of finite elements may be utilized in the numerical analysis depending on the interpolation field that is selected, and it is generally known that convergence to the proper value will occur considerably more quickly with a good displacement pattern than with a poor pattern, saving computation time. The method for creating finite elements using the strain approach (S.B.A.) is presented in this presentation. When the results are compared with those provided by equivalent displacement-based elements, having the same total number of degrees of freedom, an excellent convergence can be obtained through some application and validation tests using recently developed membrane elements, plate bending elements, and flat shell elements. The effectiveness and performance of the strain-based finite elements in modeling structures are proven by the findings for deflections and stresses.

Keywords: finite elements, plate bending, strain approach, displacement formulation, shell element

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Authors: M. Movahedi Rad

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In this study, a general approach to the reliability based limit analysis of laterally loaded piles is presented. In engineering practice, the uncertainties play a very important role. The aim of this study is to evaluate the lateral load capacity of free head and fixed-head long pile when the plastic limit analysis is considered. In addition to the plastic limit analysis to control the plastic behaviour of the structure, uncertain bound on the complementary strain energy of the residual forces is also applied. This bound has a significant effect for the load parameter. The solution to reliability-based problems is obtained by a computer program which is governed by the reliability index calculation.

Keywords: reliability, laterally loaded pile, residual strain energy, probability, limit analysis

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Authors: Innocent Kafodya, Guijun Xian

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This paper presents effects of distilled water, seawater and sustained bending strains of 30% and 50% ultimate strain at room temperature, on the durability of unidirectional pultruded carbon fiber reinforced polymer (CFRP) plates. In this study, dynamic mechanical analyzer (DMA) was used to investigate the synergic effects of the immersions and bending strains on the visco-elastic properties of (CFRP) such as storage modulus, tan delta and glass transition temperature. The study reveals that the storage modulus and glass transition temperature increase while tan delta peak decreases in the initial stage of both immersions due to the progression of curing. The storage modulus and Tg subsequently decrease and tan delta increases due to the matrix plasticization. The blister induced damages in the unstrained seawater samples enhance water uptake and cause more serious degradation of Tg and storage modulus than in water immersion. Increasing sustained bending decreases Tg and storage modulus in a long run for both immersions due to resin matrix cracking and debonding. The combined effects of immersions and strains are not clearly reflected due to the statistical effects of DMA sample sizes and competing processes of molecular reorientation and postcuring.

Keywords: pultruded CFRP plate, bending strain, glass transition temperature, storage modulus, tan delta

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Authors: Humayun Kabir, Amirul Hasan, Yu Miyaoka, Makiko Yamaguchi, Chisaki Kadota, Kazuaki Takehara

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From field isolates of Newcastle disease virus (NDV) in Japan, one avirulent strain, APMV/northern pintail/Japan/Aomori/2003 (dk-Aomori/03, NDV 261), was selected for its excellent thermostability, and the strain was heat-treated at 56℃ temperatures for 30 min with each passage into Vero cells to maintain thermostability and to adapt Vero cells. After serial 20 passages in Vero cells, it was named NDV Vero20. When growth curves were tested in Vero cells, NDV Vero20 grew well to compare the original NDV261. The HN gene was sequenced, and found motifs that show thermostability. The intracerebral pathogenicity index (ICPI) test score was 0. The thermostability of the virus was confirmed by storing it at different temperatures, including at 37°C. When susceptible chicks were inoculated with NDV Vero20 through eye drops, induced adequate levels of antibody were measured using a serum neutralization test. The results showed that NDV Vero20, a vaccine candidate strain is thermostable, Vero cell adapted, and has immunogenic potential, which would make as an alternative to the traditional embryonated chicken eggs-based vaccine.

Keywords: Newcastle disease virus, thermostability, vaccine, Vero cell adaptability

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Authors: M. Ghosh, A. Miroux, L. A. I. Kestens

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At molecular or micrometre scale, practically all materials are neither homogeneous nor isotropic. The concept of texture is used to identify the structural features that cause the properties of a material to be anisotropic. For metallic materials, the anisotropy of the mechanical behaviour originates from the crystallographic nature of plastic deformation, and is therefore controlled by the crystallographic texture. Anisotropy in mechanical properties often constitutes a disadvantage in the application of materials, as it is often illustrated by the earing phenomena during drawing. However, advantages may also be attained when considering other properties (e.g. optimization of magnetic behaviour to a specific direction) by controlling texture through thermo-mechanical processing). Nevertheless, in order to have better control over the final properties it is essential to relate texture with materials processing route and subsequently optimise their performance. However, up to date, few studies have been reported about the evolution of texture in 6061 aluminium alloy during warm processing (from room temperature to 250ºC). In present investigation, recrystallized 6061 aluminium alloy samples were subjected to tensile and plane strain compression (PSC) at room and warm temperatures. The gradual change of texture following both deformation modes were measured and discussed. Tensile tests demonstrate the mechanism at low strain while PSC does the same at high strain and eventually simulate the condition of rolling. Cube dominated texture of the initial rolled and recrystallized AA6061 sheets were replaced by domination of S and R components after PSC at room temperature, warm temperature (250ºC) though did not reflect any noticeable deviation from room temperature observation. It was also noticed that temperature has no significant effect on the evolution of grain morphology during PSC. The band contrast map revealed that after 30% deformation the substructure inside the grain is mainly made of series of parallel bands. A tendency for decrease of Cube and increase of Goss was noticed after tensile deformation compared to as-received material. Like PSC, texture does not change after deformation at warm temperature though. n-fibre was noticed for all the three textures from Goss to Cube.

Keywords: AA 6061, deformation, temperature, tensile, PSC, texture

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Authors: Shiva Emami, Jenny Persson, Bengt Johansson Lindbom

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Group A streptococcus (GAS) is a prevalent human pathogen, causing a wide range of infections and diseases. One of the most well-known virulence factors in GAS is M protein, a surface protein that facilitates bacterial invasion. In this study, we used a recombinant GAS strain (GAS-2W) expressing M protein containing a hyper immunogenic peptide (2W). Mice were immunized three times with heat-killed-GAS subcutaneously at three weeks intervals. Three weeks post last immunization, mice were challenged intraperitoneally with a lethal dose of live GAS. In order to investigate the impact of IFN-ƴ and antibodies in protection against GAS infection, we used a mouse model knock-out for IFN-ƴ (IFN-ƴ KO). We observed immunization with GAS-2W strain can increase protection against GAS infection in mice compared with the original GAS strain. Higher levels of antibodies against M1 protein were measured in GAS-2W-immunized mice. There was also a significant increase in IgG2c response in mice immunized with GAS2W. By using IFN-ƴ KO mice, we showed that not a high level of total IgG, but IgG2c was correlated with protection through the i.p challenge. It also emphasizes the importance of IFN-ƴ cytokine to combat GAS by isotype switching to IgG2c (which is opsonic for phagocytosis). Our data indicate the crucial role of IFN-ƴ in the protective immune response that, together with IgG2c, can induce protection against GAS.

Keywords: Group A streptococcus, IgG2c, IFN-γ, protection

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Authors: Ayodeji O. Falade, Leonard V. Mabinya, Uchechukwu U. Nwodo, Anthony I. Okoh

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Given the high-utility of peroxidase, its production in large amount is of utmost importance. Over the years, actinomycetes have been the major peroxidase-producing bacteria. Consequently, other classes of bacteria with peroxidase production potentials are underexplored. This study, therefore, sought to enhance peroxidase production by a Raoultella species, a new ligninolytic proteobacteria strain, by determining the optimum culture conditions (initial pH, incubation temperature and agitation speed) for peroxidase production under submerged fermentation using the classical process of one variable at a time and supplementing the fermentation medium with some lignin model and inorganic nitrogen compounds. Subsequently, the time-course assay was carried out under optimized conditions. Then, some agricultural residues were valorized for peroxidase production under solid state fermentation. Peroxidase production was optimal at initial pH 5, incubation temperature of 35 °C and agitation speed of 150 rpm with guaiacol and ammonium chloride as the best inducer and nitrogen supplement respectively. Peroxidase production by the Raoultella species was optimal at 72 h with specific productivity of 16.48 ± 0.89 U mg⁻¹. A simultaneous production of a non-peroxide dependent extracellular enzyme which suggests probable laccase production was observed with specific productivity of 13.63 ± 0.45 U mg⁻¹ while sawdust gave the best peroxidase yield under solid state fermentation. In conclusion, peroxidase production by the Raoultella species was increased by 3.40-fold.

Keywords: enzyme production, ligninolytic bacteria, peroxidase, proteobacteria

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Authors: Surasak Siripornadulsil, Nutt Poomai, Wilailak Siripornadulsil

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Due to a high ethanol demand, the approach for effective ethanol production is important and has been developed rapidly worldwide. Several agricultural wastes are highly abundant in celluloses and the effective cellulose enzymes do exist widely among microorganisms. Accordingly, the cellulose degradation using microbial cellulose to produce a low-cost substrate for ethanol production has attracted more attention. In this study, the cellulose producing bacterial strain has been isolated from rich straw and identified by 16S rDNA sequence analysis as Acinetobacter sp. KKU44. This strain is able to grow and exhibit the cellulose activity. The optimal temperature for its growth and cellulose production is 37 °C. The optimal temperature of bacterial cellulose activity is 60 °C. The cellulose enzyme from Acinetobacter sp. KKU44 is heat-tolerant enzyme. The bacterial culture of 36 h. showed highest cellulose activity at 120 U/mL when grown in LB medium containing 2% (w/v). The capability of Acinetobacter sp. KKU44 to grow in cellulosic agricultural wastes as a sole carbon source and exhibiting the high cellulose activity at high temperature suggested that this strain could be potentially developed further as a cellulose degrading strain for a production of low-cost substrate used in ethanol production.

Keywords: cellulose enzyme, bagasse, rice straw, rice husk, acinetobacter sp. KKU44

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Authors: Bensaid Fatiha

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The objective of our present work is the description of the antagonistic capacities of one strain of Pseudomonas fluorescens and the nonpathogenic fungic isolate Fusarium oxysporum against phytopathogenic agent Fusarium oxysporum F. Sp. lycopersici. This work has been achieved in two main parts: the first is interested on the in vitro antagonistic activities; the second was interested to study the soil receptiveness of fusarium wilt tomato. The use of strain of fluorescent Pseudomonas and a non-pathogenic strain of F. oxysporum in the different antagonism tests, has allowed assuring a certain bio-protection from the plants of tomatoes opposite to F. oxysporum F. Sp. lycopersici, agent of a wilt of tomato. These antagonistic have shown a substantial in vitro antagonistic activity on the three mediums (KB, PDA, KB+PDA) against F. oxysporum F. Sp. lycopersici, by inhibiting its growth mycelium with rate of inhibition going until 80 % with non-pathogen of Fusarium oxysporum and 60 % with strain of fluorescens Pseudomonas. Soil microbial balance, between the antagonistic population and that of pathogenic, can be modulated through microbiological variations or abiotic additives influencing directly or indirectly the metabolic behavior microbial. In this experiment, addition of glucose or EDTA, could increase or decrease the resistance of soil by activation of pathogenic or antagonists, as a result of modification and modulation in their metabolic activities.

Keywords: fluorescents, nonpathogenic, fusarium oxysporum, fusarium wilt, antagonism, biological control, soil receptivity

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Authors: Refal Hussain, Saifuddin M. Nomanbhay

Abstract:

Glycerol is a valuable raw material for the production of industrially useful metabolites. Among many promising applications for the use of glycerol is its bioconversion to high value-added compounds, such as bioethanol through microbial fermentation. Bioethanol is an important industrial chemical with emerging potential as a biofuel to replace vanishing fossil fuels. The yield of liquid fuel in this process was greatly influenced by various parameters viz, temperature, pH, glycerol concentration, organic concentration, and agitation speed were considered. The present study was undertaken to investigate optimum parameters for bioethanol production from raw glycerol by immobilized mutant Escherichia coli (E.coli) (ATCC11505) strain on chitosan cross linked glutaraldehyde optimized by Taguchi statistical method in shake flasks. The initial parameters were set each at four levels and the orthogonal array layout of L16 (45) conducted. The important controlling parameters for optimized the operational fermentation was temperature 38 °C, medium pH 6.5, initial glycerol concentration (250 g/l), and organic source concentration (5 g/l). Fermentation with optimized parameters was carried out in a custom fabricated shake flask. The predicted value of bioethanol production under optimized conditions was (118.13 g/l). Immobilized cells are mainly used for economic benefits of continuous production or repeated use in continuous as well as in batch mode.

Keywords: bioethanol, Escherichia coli, immobilization, optimization

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Authors: A. Baqqal, O. Abduhamid, H. Abdul-Hameed, T. Messager, G. Ayoub

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In this contribution, the effect of crystal content on the cyclic response of semi-crystalline polyethylene is studied over a large strain range. Experimental observations on a high-density polyethylene with 72% crystal content and an ultralow density polyethylene with 15% crystal content are reported. The cyclic stretching does appear a thermoplastic-like response for high crystallinity and an elastomeric-like response for low crystallinity, both characterized by a stress-softening, a hysteresis and a residual strain, whose amount depends on the crystallinity and the applied strain. Based on the experimental observations, a unified viscoelastic-viscoplastic constitutive model capturing the polyethylene cyclic response features is proposed. A two-phase representation of the polyethylene microstructure allows taking into consideration the effective contribution of the crystalline and amorphous phases to the intermolecular resistance to deformation which is coupled, to capture the strain hardening, to a resistance to molecular orientation. The polyethylene cyclic response features are captured by introducing evolution laws for the model parameters affected by the microstructure alteration due to the cyclic stretching.

Keywords: cyclic loading unloading, polyethylene, semi-crystalline polymer, viscoelastic-viscoplastic constitutive model

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Authors: Jerry John T. M., Sylas V. P., Shijo Joy

Abstract:

Hydrogen is the most essential gas that can be used for many purposes. During the production of hydrogen using raw materials like Soil and leftover cooked rice water (kanjivellam), the major by-product formed is water. Soil is collected from three different places in kottayam district: Kallara, Meenachilar, and Athirampuzha. Collected samples are mixed with rice water and tested for traces of hydrogen using a biohydrogen sensor after 72 hours. The result was the presence of hydrogen in all the 3 samples. After streaking, PCR and gel electrophoresis detected the bacteria which produced the hydrogen. RGCB Thiruvananthapuram conducted the sequencing of the PCR resultant. And identified the bacterial strains. Five variants of Bacillus bacteria ( (1) Bacillus cereus strain JTM GenBank: OP278839.1 (2) Bacillus toyonensis strain JTM2 GenBank: OP278841.1 (3) Bacillus anthracis strain JTM_SR2989-3-R_H08 GenBank: OP278960.1 (4) Bacillus thuringiensis strain JRY1 GenBank: OP278976.1 (5) Bacillus anthracis strain JTM_SR2989-3-F_H07 GenBank: OP278959.1 ) are identified and successfully registered in NCBI Gen bank. These Bacillus bacteria are major types of Rhizobacteria that can form spores and can survive in the soil for a long time period under harsh environmental conditions. Also, plant growth is enhanced by PGPR (Plant growth promoting rhizobacteria) through the induction of systemic resistance, antibiosis, and competitive omission. The molecular sequencing was submitted to the NCBI Gen Bank, and the accession numbers were allotted for the bacterial cultures.

Keywords: bio hydrogen production, bacterial bio hydrogen production, plant related to bacillus bacteria., bacillus bacteria study

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Authors: F. Z. Aliyat, M. El Guilli, L. Nassiri, J. Ibijbijen

Abstract:

Climate change is becoming a crucial factor that can significantly impact all ecosystems. It has a negative impact on the environment in many parts of the planet. Agriculture is the main sector affected by climate change. Particularly, the salinity of agricultural soils is among the problems caused by climate change. The use of phosphate solubilizing bacteria (PSB) as a biofertilizer requires previous research on their tolerance to abiotic stress, specifically saline stress tolerance, before the formation of biofertilizers. In this context, the main goal of this research was to assess the salinity tolerance of four strains: Serratia rubidaea strain JCM1240, Enterobacter bugandensis strain 247BMC, Pantoea agglomerans strain ATCC 27155, Pseudomonas brassicacearum subsp. Neoaurantiaca strain CIP109457, which was isolated from solid phosphate sludge. Additionally, their capacity to solubilize potassium and zinc, as well as their effect on Wheat (Triticum Durum 'Karim') germination. The four PSB strains were tested for their ability to solubilize phosphate in NBRIP medium with tricalcium phosphate (TCP) as the sole source of phosphorus under salt stress. Five concentrations of NaCl were used (0%, 0.5%, 1%, 2.5%, 5%). Their phosphate solubilizing activity was estimated by the vanadate-molybdate method. The potassium and zinc solubilization has been tested qualitatively and separately on solid media with mica and zinc oxide as the only sources of potassium and zinc, respectively. The result showed that the solubilization decreases with the increase in the concentration of NaCl; all the strains solubilize the TCP even with 5% NaCl, with a significant difference among the four strains. The Serratia rubidaea strain was the most tolerant strain. In addition, the four strains solubilize the potassium and the zinc. The Serratia rubidaea strain was the most efficient. Therefore, biofertilization with PSB salt-tolerant strains could be a climate-change-preparedness strategy for agriculture in salt soil.

Keywords: bioavailability of mineral nutrients, phosphate solid sludge; phosphate solubilization, potassium solubilization, salt stress, zinc solubilization.

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Authors: Seok Hong Min, Tae Kwon Ha

Abstract:

High-temperature deformation behavior of ferritic stainless steels such as STS 409L, STS 430J1L, and STS 429EM has been investigated in this study. Specimens with fully annealed microstructure were obtained by heat treatment. A series of load relaxation tests has been conducted on these samples at temperatures ranging from 200 to 900oC to construct flow curves in the strain rate range from 10-6 s-1 to 10-3 s-1. Strain hardening was not observed at high temperatures above 800oC in any stainless steels. Load relaxation behavior at the temperature was closely related with high-temperature mechanical properties such as the thermal fatigue and tensile behaviors. Load drop ratio of 436L stainless steel was much higher than that of the other steels. With increasing temperature, strength and load drop ratio of ferritic stainless steels showed entirely different trends.

Keywords: ferritic stainless steel, high temperature deformation, load relaxation, microstructure, strain rate sensitivity

Procedia PDF Downloads 302