Simple torsion test for shear moduli determination of orthotropic composites

By means of torsion tests performed on test specimens of the same material having a minimum of two different cross sections (flat sheet of different widths), the effective in-plane (G13) and out-of-plane (G23) shear moduli were determined for two composite materials of uniaxial and angleply fiber orientations. Test specimens were 16 plies (nominal 2 mm) thick, 100 mm in length, and in widths of 6.3, 9.5, 12.5, and 15.8 mm. Torsion tests were run under controlled deflection (constant angle of twist) using an electrohydraulic servocontrolled test system. In-plane and out-of-plane shear moduli were calculated from an equation derived in the theory of elasticity which relates applied torque, the torsional angle of twist, the specimen width/thickness ratio, and the ratio of the two shear moduli G13/G23. Results demonstrate that torsional shear moduli, G23 as well as G13, can be determined by simple torsion tests of flat specimens of rectangular cross section. Neither the uniaxial nor angleply composite material were transversely isotropic

Study of strain-hardening near crack tips

Elastic-plastic analysis of stresses and strains near crack tip

Measuring and reporting of intellectual capital: with special reference to commercial banks in Sri Lanka

Importance and growing pressure from shareholders on Intellectual Capital (IC) have been increased over the past decades since managing, measuring and reporting oflC is becoming recognized as an important strategy for transparency and more complete information on the potential profitability and growth of organizations in competitive environment. However, Sri Uinkan companies still give little importance for the measuring and reporting of IC. Thus, the objective of this study is to develop a measuring and reporting framework for IC in Sri Utnkan contexts. This study is conducted over five limited liability commercial banking companies currently operating in Sri Lanka. Study found that measuring and reporting framework for IC was developed in western countries could be applied in Sri Lankan contexts with required adjustments based on stakeholders' prospective and available information

Power smoothing and energy storage sizing of vented oscillating water column wave energy converter arrays

Oscillating water column wave energy converter arrays can be arranged to enhance the energy production and quality of power delivered to the grid. This study investigates four different array configurations of vented oscillating water columns and their effect on power quality and capacity of the energy storage systems required to absorb power fluctuation. Configuring the array of vented oscillating water columns as a nearshore detached breakwater allows combining the benefits of their complementary features. This increases the economic optimization of wave energy converters, paving the path to the energy market. The operations of the integration schemes are evaluated using the results obtained from simulations carried out using MATLAB/Simulink software. Simulation results show that the array of vented oscillating water columns and array of vented oscillating water columns as nearshore detached breakwater configurations increase the quality of power delivered to the grid and reduce the capacity of the energy storage systems required

Studies on serine protease inhibitors in the bark extract of derris parviflora

Proteases are enzymes that conduct proteolysis by the hydrolytic cleavage of specific peptide bonds in the polypeptide chain of target proteins. Serine proteases are one of the best-characterized families of proteases. Protease inhibitors (PIs) are the compounds that inhibit or modulate the activities of proteases thus exerting dramatic biological effects. Plant originated protease inhibitors are widely used in research, therapeutic and biotechnological applications. Plant PIs (PPIs) are generally small molecules, ranged from 8 kDa – 25 kDa in size. Derrisparviflorais a climbing leguminous plant in which the roots contain rotenone, a strong insecticide and fish poison which is used in fishing. The present study was conducted to investigate the occurrence of serine protease inhibitors in the bark extract of Derrisparviflora and their properties. Bark of Derrisparviflora was crushed using liquid N2 and powdered samples were homogenized using ice cold distilled water to prepare 5%, 10% and 20% extracts. Serine protease inhibitory activity of the crude bark extract was determined using trypsin as the enzyme. Trypsin activity was evaluated using casein as the substrate at pH 7.6 in 0.05 M phosphate buffer. The optimized conditions were used to modify the assay by introducing the additional step to determine the serine protease inhibitory activity. The molecular weight of the inhibitory substance was estimated by dialyzing the crude extract in phosphate buffer (pH 7.6) using a dialysis bag with a molecular weight cut off point of 8 kDa. Partial purification of the serine protease inhibitor/s in the bark extract was carried out using DEAE cellulose chromatography. Assay procedures used to determine the trypsin inhibitory activities for 5%, 10% and 20% crude extracts were able to give 51.56%, 58.36% and 60.75% respectively. As 5% crude bark extract showed a significant inhibition, it was optimized for further studies. The optimum volume of the crude extract which exhibited the highest inhibition was 30μl. There is no reduction in the inhibitory activity when dialyzed suggesting that the inhibitor/s is a macromolecule with a molecular mass greater than 8 kDa. Eluted fractions from DEAE-cellulose column showed a significant inhibitory activity suggesting that inhibitory substance binds to DEAE-cellulose. Bark of Derris parviflora contains significant serine protease inhibitory activity and the inhibitory substance could probably be a protein or a high molecular weight substance. Further studies on the characterization of this protease inhibitory substance of Derris parviflora is in progress