02351nas a2200229 4500008004100000022001400041245006400055210006300119260010600182300001200288490000800300520156300308653002301871653001601894653001301910653002301923100001901946700001801965700002001983700002102003856009702024 2014 eng d a0009-250900aModeling chain-end scission using the fixed pivot technique0 aModeling chainend scission using the fixed pivot technique aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcSEP a601-6100 v1163 a

Chain-end scission of polymer molecules is the breakage of a fixed-size oligomer or monomer from either end of the macromolecule. A common example is the generation of the glucose monomer from the hydrolysis of starch by glucoamylase. Modeling the dynamics of chain-end scission from first principles by considering each molecular size is challenging due to the large number of differential equations to be solved. The Population Balance Modeling (PBM) is a helpful framework as it could be formulated to lump a few molecular sizes together. However, it is then not obvious how to accurately account for the temporal evolution of the low molecular weight species, which is often of the greatest industrial interest. Here, the Fixed Pivot (FP) technique - one of the methods to solve PBM equations was appropriately modified to address this difficulty. By treating the lower molecular size range as a discrete domain in conjunction with a continuous domain in the upper ranges, the modified FP technique not only retains its original strengths, but also captures accurately the distribution of oligomers including the monomer. The results, which were obtained at a fraction of computational expense, benchmarked very well against the exact solutions for a polymer with a broad size distribution at different Degrees of Polymerization up to similar to O(10(5)). To facilitate wider adoption, guidelines on choice of pivots and observations of the performance of the modified FP technique are also deliberated. (C) 2014 Elsevier Ltd. All rights reserved.

10aChain-end scission10aFixed Pivot10aPolymers10aPopulation balance1 aHo, Yong, Kuen1 aDoshi, Pankaj1 aYeoh, Hak, Koon1 aNgoh, Gek, Cheng uhttps://library.ncl.res.in/content/modeling-chain-end-scission-using-fixed-pivot-technique-002363nas a2200229 4500008004100000022001400041245006400055210006400119260008400183300000900267490000700276520160800283653002401891653001701915653001601932653002001948653001801968100001801986700001802004700002002022856009102042 2015 eng d a0997-754600aDripping dynamics of newtonian liquids from a tilted nozzle0 aDripping dynamics of newtonian liquids from a tilted nozzle a23 RUE LINOIS, 75015 PARIS, FRANCEbGAUTHIER-VILLARS/EDITIONS ELSEVIERcMAY-JUN a8-150 v513 a

The dripping dynamics of Newtonian liquids emanating from an inclined nozzle is studied. The fluid viscosity mu flow rate Q, nozzle radius R, and inclination angle theta have been varied independently. The drop breakup times and the different modes of dripping have been identified using high speed imaging. A phase diagram showing the transition between the dripping modes for different theta is constructed in the (We, Ka) space, where We (Weber number) measures the relative importance of inertia to surface tension force and Ka (Kapitza number) measures the relative importance of viscous to surface tension forces. At low values of We and Ka, the system shows a transition from period-1 to limit cycle before chaos. The limit cycle region narrows down with increase in inclination. Further increase in the values of We and Ka gives a direct transition from period-1 to chaos. The new experiments reveal that in the period-1 region, increasing the nozzle inclination angle theta results in lowering of the drop breakup time t(b), suggesting that the surface tension forces cannot hold the drops longer despite the weakened effective gravitational pull. This counter-intuitive finding is further corroborated by pendant drop experiments and computations. More curiously, throughout the period-1 regime, the drop volume is independent of the flow rate. This resulted in a relatively simple correlation for the dimensionless drop volume V = 1.3G(-1)Ka(0.02)(cos theta)(0.37) accurate to within 10% over wide ranges of the independent variables. (C) 2014 Elsevier Masson SAS. All rights reserved.

10aAsymmetric dripping10aBreakup time10aDrop volume10aInclined nozzle10aPhase diagram1 aTaur, Amaraja1 aDoshi, Pankaj1 aYeoh, Hak, Koon uhttps://library.ncl.res.in/content/dripping-dynamics-newtonian-liquids-tilted-nozzle-003148nas a2200217 4500008004100000022001400041245013200055210006900187260006700256300001400323490000800337520227200345653002402617653003202641653005102673100001902724700001802743700002002761700002102781856012802802 2015 eng d a0006-359200aInterlinked population balance and cybernetic models for the simultaneous saccharification and fermentation of natural polymers0 aInterlinked population balance and cybernetic models for the sim a111 RIVER ST, HOBOKEN 07030-5774, NJ USAbWILEY-BLACKWELLcOCT a2084-21050 v1123 a

Simultaneous Saccharification and Fermentation (SSF) is a process where microbes have to first excrete extracellular enzymes to break polymeric substrates such as starch or cellulose into edible nutrients, followed by in situ conversion of those nutrients into more valuable metabolites via fermentation. As such, SSF is very attractive as a one-pot synthesis method of biological products. However, due to the co-existence of multiple biochemical steps, modeling SSF faces two major challenges. The first is to capture the successive chain-end and/or random scission of the polymeric substrates over time, which determines the rate of generation of various fermentable substrates. The second is to incorporate the response of microbes, including their preferential substrate utilization, to such a complex broth. Each of the above-mentioned challenges has manifested itself in many related areas, and has been competently but separately attacked with two diametrically different tools, i.e., the Population Balance Modeling (PBM) and the Cybernetic Modeling (CM), respectively. To date, they have yet to be applied in unison on SSF resulting in a general inadequacy or haphazard approaches to examine the dynamics and interactions of depolymerization and fermentation. To overcome this unsatisfactory state of affairs, here, the general linkage between PBM and CM is established to model SSF. A notable feature is the flexible linkage, which allows the individual PBM and CM models to be independently modified to the desired levels of detail. A more general treatment of the secretion of extracellular enzyme is also proposed in the CM model. Through a case study on the growth of a recombinant Saccharomyces cerevisiae capable of excreting a chain-end scission enzyme (glucoamylase) on starch, the interlinked model calibrated using data from the literature (Nakamura et al., Biotechnol. Bioeng. 53:21-25, 1997), captured features not attainable by existing approaches. In particular, the effect of various enzymatic actions on the temporal evolution of the polymer distribution and how the microbes respond to the diverse polymeric environment can be studied through this framework. Biotechnol. Bioeng. 2015;112: 2084-2105. (c) 2015 Wiley Periodicals, Inc.

10acybernetic modeling10apopulation balance modeling10asimultaneous saccharification and fermentation1 aHo, Yong, Kuen1 aDoshi, Pankaj1 aYeoh, Hak, Koon1 aNgoh, Gek, Cheng uhttps://library.ncl.res.in/content/interlinked-population-balance-and-cybernetic-models-simultaneous-saccharification-and-0