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Bandyopadhyay S.,Maulana Abul Kalam Azad University of Technology
International Journal of Advanced Manufacturing Technology | Year: 2010

This paper focuses on the facility location problem with two conflicting objectives. We observe that minimization of the total cost of a particular echelon may lead to the increase in the total cost of a supply chain as a whole. Thus, these conflicting objectives are required to be met together from a supply chain perspective. We have solved the problem formulated in mixed nonlinear programming by a multi-objective evolutionary algorithm (MOEA) known as non-dominated sorting algorithm, or NSGA II in short. Numerical example is provided to show the effect of the algorithm on the solution. © 2010 Springer-Verlag London Limited. Source

Bhattacharya R.,Jadavpur University | Bandyopadhyay S.,Maulana Abul Kalam Azad University of Technology
International Journal of Advanced Manufacturing Technology | Year: 2011

A review of the past research studies on the causes of bullwhip effect is presented in this paper. This paper is an effective study from the point of view that it presents a detailed classified study of the overall research studies on the effect of both the operational and the behavioral factors on bullwhip effect. A total of 19 causes of bullwhip effect have been shown here. We have identified the various gaps of research in the past research studies. An overview of the steps taken by the industries in order to tackle the bullwhip effect is also provided at the end of this paper. Directions for further research studies are also provided in each subsection of this study and at the end of this paper. © Springer-Verlag London Limited 2010. Source

Chatterjee S.,Maulana Abul Kalam Azad University of Technology
Journal of Advanced Pharmaceutical Technology and Research | Year: 2015

Microbial alkaline protease has become an important industrial and commercial biotech product in the recent years and exerts major applications in food, textile, detergent, and pharmaceutical industries. By immobilization of microbes in different entrapment matrices, the enzyme produced can be more stable, pure, continuous, and can be reused which in turn modulates the enzyme production in an economical manner. There have been reports in support of calcium alginate and corn cab as excellent matrices for immobilization of Bacillus subtilis and Bacillus licheniformis, respectively. This study has been carried out using calcium alginate, κ-carrageenan, agar-agar, polyacrylamide gel, and gelatin which emphasizes not only on enzyme activity of immobilized whole cells by different entrapment matrices but also on their efficiency with respect to their reusability as first attempt. Gelatin was found to be the best matrix among all with highest enzyme activity (517 U/ml) at 24 h incubation point and also showed efficiency when reused. Source

Mukherjee I.,Jadavpur University | Moulik S.P.,Jadavpur University | Rakshit A.K.,Maulana Abul Kalam Azad University of Technology
Journal of Colloid and Interface Science | Year: 2013

Amphiphile adsorption at the air/water interface lowers the surface tension (γ) of the solution. After a critical surfactant concentration (C), γ becomes constant (with a break in the γ-logC plot), which is considered the critical micelle concentration (CMC). At very low amphiphile concentration, γ decreases slowly, forming a plateau, then decreases sharply and often nonlinearly by a co-operative adsorption process till the second plateau is reached at CMC. To get the Gibbs surface excess (Γ) of the amphiphile relative to water, a polynomial equation of appropriate degree needs to be used, since the drop in γ progresses with continuous changing slope, which maximizes at CMC and becomes zero afterward. Recent research has evidenced that a complete saturated Gibbs monolayer may not always form at CMC; there may be formation of multilayer of micelles below the Gibbs monolayer, which cannot be assessed by ST measurements. A method like neutron reflectometry (NR) can evaluate the Γ beyond CMC. A procedure for determining Γmax from tensiometric results is herein proposed. Amphiphiles do sometimes show a linear decline in γ with logC followed by a break with a plateau at CMC. There, a single slope leading to a single surface excess quantity is obtained for the Gibbs equation at all concentrations up to CMC. Possible reasons for such results are given. Current conflicting ideas and criticisms on the issue of Gibbs equation and determination of Γ and Γmax have been addressed. © 2012 Elsevier Inc. Source

Samanta T.B.,Maulana Abul Kalam Azad University of Technology
Indian Journal of Biotechnology | Year: 2012

The constraint in synthesis of ß-lactams by penicillin acylase is the hydrolysis of the activated acyl donor and the synthetic product. The thermodynamically controlled synthesis of ß-lactams deals with direct acylation of a nucleophile (6- APA, 7-ACA or 7-ADCA) by free acids in acidic pH and high concentration of solvent to achieve good yield. On the other hand, the kinetically controlled synthesis with esters is much faster. However, success and yield of kinetically controlled synthesis depend on combined application of an insolubilized catalyst, optimum pH of the reaction, addition of suitable solvent and high concentration of actvated acyl donor and ß-lactam nucleus. Water miscible solvents play an important role in the synthesis. The choice of solvent is guided by its inhibitory effect on enzyme activity and deleterious effect on enzyme stability. Synthetic yield of cefazolin in presence of water-miscible solvent is reduced, while the reaction carried in water- immiscible solvent markedly improves the yield of cefazolin, possibly due to reduction in hydrolysis of acyl donor and the product. Ethylene glycol inhibits more the hydrolysis of ampicillin than the hydrolysis of PGME and the synthetase/amidase ratio varies depending on the concentration of the solvent used. Hydrolytic vs synthetic activity of penicillin acylase is also influenced by water activity of the insolubilized catalyst. Shuffling of PA-encoding genes has been shown to improve the ß- lactam synthesis. Delineation of enzyme-solvent interaction needs close scrutiny to ensure further success in biocatalysis and synthesis of ß-lactams in particular. Source

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