VISCOELASTIC, SWELLING KINETIC AND DRUG RELEASE CHARACTERIZATION OF POLY (ACRYLIC ACID)-GRAFTED-GELLAN

Lyophilic, viscoelastic, swelling kinetic and drug release characterizations of poly (acrylic acid) –grafted-gellan (PAAc-g-GG) were the main objective of this study. At first, a suitable solvent for PAA-g-GG was found out by lyophilicity study followed by viscoelastic study on PAAc-g-GG with different degree of grafting. The study showed that the degree of grafting greatly influences the viscoelastic nature of copolymer, which further governs the drug release pattern from the polymer matrix. The copolymer with highest grafting showed much higher starting % strain (17.73%), stress (53.3 Pa) for structural breakdown at Gꞌ = Gꞌꞌ (213.5 Pa), higher storage modulus (G’), much higher values of complex viscosity (11.46 Pa.s) and cross-over point (Gꞌ = Gꞌꞌ =271.86 Pa) compared to that of low-grafted copolymer. In 0.1N HCl, swelling index (%WE) is found to be directly proportional to percentage grafting (%G) and batches with higher grafting exhibited lowest initial swelling rate demonstrating its inversely proportional relation to %G. Equilibrium swelling and hydration are also found to be proportional to %G. The same effect has been observed in PBS with exception that the magnitude of the parameters obtained in PBS is very much higher compared to that in 0.1N HCl. The copolymer showed sustained drug release over 10 hours period and the study revealed Case-1 Fickian diffusion or square root of time kinetic based release mechanism. The study reveales that viscoelastic and swelling study might be useful to understand how the degree of grafting governs the drug release

Numerical Study About the Change in Flow Separation and Velocity Distribution in a 90° Pipe Bend with/without Guide Vane Conditions

A single phase, incompressible turbulent flow through a 90º pipe bend with/without guide vane conditions has been studied here. The present work deals with the numerical simulation to investigate the change in flow separation and velocity distribution at the downstream section due to the effect of the guide vane.  The k-? turbulence model has been adopted for simulation purposes to obtain the results. After the validation of existing experimental and numerical results, a detailed study has been performed for three different Reynolds number and four different positions of the guide vane. The value of the Curvature ratio (Rc/D) has been considered as one factor for the present study. The curvature ratio can be defined as the ratio between the bend curvature radius and hydraulic diameter of the pipe. The results obtained from the present study have been presented in graphical form. A flow separation region has been found at the bend outlet for flow through 90º pipe bend without the guide vane. This flow separation region was absent for the cases which dealt with the flow through 90º pipe bend with the guide vane. Velocity distribution at four different downstream positions for different cases and different Reynolds numbers have been compared and reported in the present study

Enzyme activity in banana fruits rotted by Botryodiplodia theobromae Pat.

Peroxidase and polyphenol oxidase activities in fruits of two cultivars of banana, 'champa' and 'kanthali' rotted by Botryodiplodia theobromae Pat. was studied. The enzymes showed much higher activities in infected than that in uninfected 'tissues. Increase in peroxidase activity was evidently inhibited by cycloheximide. Polyphenol oxidase activity was also inhibited in presence of phenylthiourea and Na-diethyldithiocarbamate more strongly by the former. Increase in activities seemed to be due to increased sytheses of the enzymes. In an in vitro culture, the fungus exhibited some peroxidase but no polyphenoloxidase activity

Enzyme activity in banana fruits rotted by Botryodiplodia theobromae Pat.

Peroxidase and polyphenol oxidase activities in fruits of two cultivars of banana, 'champa' and 'kanthali' rotted by Botryodiplodia theobromae Pat. was studied. The enzymes showed much higher activities in infected than that in uninfected 'tissues. Increase in peroxidase activity was evidently inhibited by cycloheximide. Polyphenol oxidase activity was also inhibited in presence of phenylthiourea and Na-diethyldithiocarbamate more strongly by the former. Increase in activities seemed to be due to increased sytheses of the enzymes. In an in vitro culture, the fungus exhibited some peroxidase but no polyphenoloxidase activity

Numerical study on flow separation in 90° pipe bend under high Reynolds number by k-ε modelling

The present paper makes an effort to find the flow separation characteristics under high Reynolds number in pipe bends. Single phase turbulent flow through pipe bends is investigated using k-ε turbulence model. After the validation of present model against existing experimental results, a detailed study has been performed to study the influence of Reynolds number on flow separation and reattachment. The separation region and the velocity field of the primary and the secondary flows in different sections have been illustrated. Numerical results show that flow separation can be clearly visualized for bend with low curvature ratio. Distributions of the velocity vector show the secondary motion clearly induced by the movement of fluid from inner to outer wall of the bend leading to flow separation. This paper provides numerical results to understand the flow characteristics of fluid flow in 90° bend pipe

Numerical study on flow separation in 90° pipe bend under high Reynolds number by k-ε modelling

The present paper makes an effort to find the flow separation characteristics under high Reynolds number in pipe bends. Single phase turbulent flow through pipe bends is investigated using k-ε turbulence model. After the validation of present model against existing experimental results, a detailed study has been performed to study the influence of Reynolds number on flow separation and reattachment. The separation region and the velocity field of the primary and the secondary flows in different sections have been illustrated. Numerical results show that flow separation can be clearly visualized for bend with low curvature ratio. Distributions of the velocity vector show the secondary motion clearly induced by the movement of fluid from inner to outer wall of the bend leading to flow separation. This paper provides numerical results to understand the flow characteristics of fluid flow in 90° bend pipe

Toward an Accurate and Inexpensive Estimation of CCSD(T)/CBS Binding Energies of Large Water Clusters

Owing to the steep scaling behavior, highly accurate CCSD­(T) calculations, the contemporary gold standard of quantum chemistry, are prohibitively difficult for moderate- and large-sized water clusters even with the high-end hardware. The molecular tailoring approach (MTA), a fragmentation-based technique is found to be useful for enabling such high-level ab initio calculations. The present work reports the CCSD­(T) level binding energies of many low-lying isomers of large (H₂O)_<i>n</i> (<i>n</i> = 16, 17, and 25) clusters employing aug-cc-pVDZ and aug-cc-pVTZ basis sets within the MTA framework. Accurate estimation of the CCSD­(T) level binding energies [within 0.3 kcal/mol of the respective full calculation (FC) results] is achieved after effecting the grafting procedure, a protocol for minimizing the errors in the MTA-derived energies arising due to the approximate nature of MTA. The CCSD­(T) level grafting procedure presented here hinges upon the well-known fact that the MP2 method, which scales as O­(N⁵), can be a suitable starting point for approximating to the highly accurate CCSD­(T) [that scale as O­(N⁷)] energies. On account of the requirement of only an MP2-level FC on the entire cluster, the current methodology ultimately leads to a cost-effective solution for the CCSD­(T) level accurate binding energies of large-sized water clusters even at the complete basis set limit utilizing off-the-shelf hardware