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Present work deals with the analysis of the variation in the stresses of an inelastic composite cantilever beam. The cantilever beam is made up of four bi-directional symmetrically stacked glass-fiber/epoxy (GFRP) laminas. The stress field in the beam has been calculated using one dimensional finite element formulation of the Timoshenko beam theory. GFRP are the elastic composites and their behaviour is brittle. Thus the energy dissipation is generally given by the area under the elastic curve. The addition of the inelastic fibers in the composite extend this area after the yield stress leading to the more energy dissipation. To achieve an increase in the energy dissipation, aluminium (Al.) has been introduced as an inelastic fiber in the top-most layer and is considered to undergo kinematic hardening. Finite element formulation has been done for the aluminium reinforced glass fiber/epoxy composite cantilever beam. At small loads, even an incremental increase in the plastic area can be beneficial. The overall stiffness of the top-most layer is calculated by the rules of mixtures (Voigt) method and updated once stresses reach in the inelastic zone. As the top and the bottom most layer is made up of same composite material but the only difference is that of inelastic fibers in the top most layer, we can compare the stresses and how much energy dissipation increases in the top-most layer. The effect of varying the thickness on the stresses and energy dissipation is discussed. [ABSTRACT FROM AUTHOR]

Air flow and heat transfer inside a yogurt cooling room were analysed using Computational Fluid Dynamics. Air flow and heat transfer models were based on 3D, unsteady state, incompressible, Reynolds-averaged Navier-Stokes equations and energy equations. Yogurt cooling room was modelled with the measured geometry using 3D design tool AutoCAD. Yogurt cooling room model was exported into the flow simulation software by specifying properties of inlet air, yogurt, pallet and walls of the room. Packing material was not considered in this study because of less thickness (cup-0.5mm, carton box-1.5mm) and negligible resistance created in the conduction of heat. 3D Computational domain was meshed with hexahedral cells and governing equations were solved using explicit finite volume method. Air flow pattern inside the room and the temperature distribution in the bulk of palletized yogurt were predicted. Through validation, the variation in the temperature distribution and velocity vector from the measured value was found to be 2.0°C (maximum) and 30% respectively. From the simulation and the measured value of the temperature distribution, it was observed that the temperature was non-uniform over the bulk of yogurt. This might be due to refrigeration capacity, air flow pattern, stacking of yogurt or geometry of the room. Required results were achieved by changing the location of the cooling fan. [ABSTRACT FROM AUTHOR]

Biofouling in the marine environment is a major problem. In this study, three marine organisms, namely Bacillus flexus (LD1), Pseudomonas fluorescens (MD3) and Vibrio natriegens (MD6), were isolated from biofilms formed on polymer and metal surfaces immersed in ocean water. Phylogenetic analysis of these three organisms indicated that they were good model systems for studying marine biofouling. The in vitro antifouling activity of 47 synthesized chalcone derivatives was investigated by estimating the minimum inhibitory concentration against these organisms using a twofold dilution technique. Compounds C-5, C-16, C-24, C-33, C-34 and C-37 were found to be the most active. In the majority of the cases it was found that these active compounds had hydroxyl substitutions. A quantitative structure-activity relationship (QSAR) was developed after dividing the total data into training and test sets. The statistical measures r2, [image omitted] (>0.6) q2 (>0.5) and the F-ratio were found to be satisfactory. Spatial, structural and electronic descriptors were found to be predominantly affecting the antibiofouling activity of these compounds. Among the spatial descriptors, Jurs descriptors showed their contribution in all the three antibacterial QSARs. [ABSTRACT FROM AUTHOR]

A study was undertaken to assess the effect of betel leaves (Piper betel Linn) extract on the physico-chemical, sensory and textural properties of dahi stored under refrigerated temperature. The result revealed that pH of control decreased from 4.40 to 4.03 whereas treated the pH of dahi with 0.5% betel leaves extract was 4.23 up to the 7th day of storage. Titratable acidity for control increased from the beginning to 7th day of storage whereas for the treatment showed controlled increase at the end of the storage period and reduced firmness and consistency. Sensory evaluation (overall acceptability) was similar to that of control. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF), a piezoelectric material has many useful application like sensors transducers and surface acoustic wave devices. Since PVDF is a polymer, it is possible that its mechanical response is likely to be frequency and time dependent. It is important therefore, to characterize the frequency or time dependent behavior of PVDF using appropriate models that are based on experimental observations. Dynamical Mechanical Test were conducted on bi-axially stretched PVDF at different temperatures (35°C-70°C) and frequencies (0.33Hz-10Hz). It was observed from the experimental results that at higher temperature, the rate of change of modulus with frequency reduces. Time-temperature superposition was done for the storage and the loss modulii to arrive at a single master using a simple viscoelastic three parameter model with ordinary dashpot. This model predicted the storage modulus well but was found short of the required predictive capability for the loss modulus. A four parameter model with fractional dashpot was used and it is found that it models the loss and storage modulus results better than the model ordinary dashpot. [ABSTRACT FROM AUTHOR]

This paper presents a methodology of design for a circular flexural plate PVDF hydrophone taking into consideration the various design parameters such as acoustical parameters, structural requirement and electromechanical properties of the PVDF. Little attention has been paid in the past on a systematic design of a hydrophone considering the various design parameters. Sensitivity and static pressure capability curves obtained in this work will help the designer in selecting an appropriate design for a given application with specific design constraints. Since the support conditions affect the sensitivity drastically, two bounding conditions, namely, the simply supported and the clamped boundary conditions were considered for the design. Experiments were conducted to assess the performance of the hydrophones constructed using the proposed design methodology. Experimental results of testing the hydrophones both in air and underwater are presented. Results obtained show superiority of the hydrophones constructed using the proposed design methodology. In addition, theoretical calculations made on the designed hydrophone correlate well with the experimental observations. This demonstrates that the proposed methodology can be directly used for design of a hydrophone given the design considerations. [ABSTRACT FROM AUTHOR]

The buckling of compressively loaded members is one of the most important factors limiting the overall strength and stability of a structure. In this work, experimental work has been carried out to examine the effect of force generated by PZT on the control of buckling of a column structure. The test procedure is outlined and load strain plots, obtained with and without control are presented. A theoretical buckling analysis is also done to evaluate the critical buckling load of the test specimen using expressions available in literature. Open loop experiments demonstrate that piezoelectric force is useful in offsetting the initial imperfection induced moment. From the experience gained from the open loop experiments, closed loop experiments are carried out. Closed loop experiments demonstrate that the buckling of the column could be postponed by using a feedback loop involving piezoelectric actuation and strain gage sensing. The column with control is shown to clearly demonstrate an increase of up to 123% in axial compressive load carrying capacity compared to those without control. [ABSTRACT FROM AUTHOR]

Marine paint mixed with 2-methoxy-2',4'-dichloro chalcone is able to considerably reduce the formation of biofilm by Vibrio natriegens, a marine bacterium, on polycarbonate (PC), polymethylmethacrylate (PMMA) and glass fiber reinforced plastic (GFRP). These polymers have been selected for the study, since they have wide marine applications. Surfaces coated with dichloro chalcone containing marine paint had the lowest number of colony forming units (CFU) (1-5×10(6)), proteins (20-30 μg/cm2) and carbohydrates (5-10 μg/cm2) attached to them after 28 days of exposure to the organism when compared to surfaces coated with CuSO4 mixed paint (20-40×10(6) CFU/ml, proteins of 50-60 μg/cm2 and carbohydrates of 40-50 μg/cm2) or plain marine paint (30-40×10(6) CFU/ml, proteins of 120-150 μg/cm2 and carbohydrates of 40-60 μg/cm2). At the end of the study period, the biofilm on PMMA was 7, 10 and 12 μm thick on chalcone, copper and plain paint coated surfaces, respectively. The first two paints increased the surface roughness but decreased the surface hydrophobicity when compared to the plain paint. Large number of dead cells was found on the chalcone mixed and predominantly live cells were found on plain paint coated surfaces. 15% of dichloro chalcone had leached out of PMMA surface after 28 days. The low amount of biofilm formed in the presence of dichlorochalcone can be associated to its antibacterial and slimicidal activity and also its ability to reduce the hydrophobicity of the surface. This dichlorochalcone appears to be a novel agent for decreasing the formation of marine biofilm., (Copyright © 2010 Elsevier B.V. All rights reserved.)

A series of novel dispiropyrrolidines have been synthesized through 1,3-dipolar cycloaddition of an azomethine ylide generated from sarcosine and isatin with the dipolarophile 3-benzylidene-1-methyl-pyrrolidine-2,5-dione. Their antibacterial activity was evaluated against Bacillus subtilis NCIM 2718, Staphylococcus aureus NCIM5021, Salmonella typhi NCIM2501, Pseudomonas aeruginosa NCIM 5029 and Proteus vulgaris NCIM2813 by two fold dilution method. Compound 6e exhibits reasonably good activity and compound 6c exhibits poor activity against all the organisms. The QSAR's were developed for all antibacterial activities. The models had either one or two descriptors (r2 = 0.81-0.97, , q2 = 0.57-0.92, F-ratio = 12.73-162.76). Topology, shape, charge distribution and hydrophobic nature of the molecules had pronounced effect on their antibacterial activity.

Sixteen 1,3,5-triphenyl-2-pyrazolines were synthesized and their anti-infective activities (against Mycobacterium tuberculosis H(37)Rv, six bacterial and four fungal strains) were tested. Only compound with SO(2)CH(3) in the para position of the A-ring was active against the tubercular strain at 100 microg/ml concentration. All compounds showed good anti infective activity against Escherichia coli and poor activity against Staphylococcus aureus. Compounds 4, 12, 13 and 14 exhibited reasonable activity against all the organisms tested (<0.309 microM except against S. aureus. The activity of these compounds correlated with their lipophilic/hydrophilic nature. Compounds 4, 10 and 16 showed very good activity (>88% reduction) against four fungi studied at 2mg/ml. All these compounds possess halogen substitutions. Compound 11 showed very high activity (>90%) against three fungi. Majority of the compounds showed more than 90% inhibition against one or two fungi. Since pyrazolines are reported to inhibit the activity of p-glycoprotein, they may prevent drug resistance developed by microorganism., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Quantitative structure activity relationship (QSAR) studies of selective COX-2 inhibitors of commercial interest (drugs in market and on clinical trials) were performed. The COX-2 inhibitory activity (pIC(50)=-logIC(50)) of these twelve compounds was correlated with nineteen descriptors including steric, electronic and constitutional parameters. pIC(50) activity showed high positive correlation with both volume and HOMO (Highest occupied molecular orbital). A Biparametric model was developed that included both these descriptors. The predictive capability (q(2)= 0.66) of this equation was satisfactory. So it can be used to design newer templates or modify existing templates. Volume is an important parameter for the selective COX-2 inhibitory activity, because the secondary pocket in the active site of this enzyme is bigger than the active site of COX-1 enzyme (by 17%). HOMO is a measure of the nucleophilicity of the molecule and a molecule with high HOMO energy is ready to donate its electrons and thus is more reactive than molecule with low values. Binding studies were performed between the COX-2 enzyme and these molecules. The inhibitory activity increased with decrease in binding energy (or interaction energy) between the compounds with the COX-2 enzyme (with a correlation coefficient = -0.65). Calculated Log BBB (Blood Brain barrier), Log P (octonol water partition) and HBD (hydrogen bond donor) values were in the acceptable range (i.e., BBB = -1 to 0.3; LogP= 0 to 5; HBD < 5).

In order to develop relatively small molecules as antimycobacterial agents, twenty-five chalcones were synthesized, their activity was evaluated, and quantitative structure-activity relationship (QSAR) was developed. The synthesis was based on the Claisen-Schimdt scheme and the resultant compounds were tested for antitubercular activity by luciferase reporter phage (LRP) assay. Compound C(24) was found to be the most active ( approximately 99%) in this series based on the percentage reduction in Relative Light Units at both 50 and 100 microg/ml levels, followed by compound C(21). Four compounds at the 50 microg/ml and eight compounds at the 100 microg/ml showed activity above 90% level. QSAR model was developed between activity and spatial, topological, and ADME descriptors for the 50 microg/ml data. The statistical measures such as r, r(2), q(2), and F values obtained for the training set were in acceptable range and hence this relationship was used for the test set. The predictive ability of the model is satisfactory (q(2)=0.56) and it can be used for designing similar group of compounds.