bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimum Multiple CFSTRs for a two stage fermentation of recombinant bacteria with a sensitive switching gene
Authors: Baheri H. R. , Hill G. A. , Roesler W. J. 
Published: March 2009

AbstractThe effect of increasing the number of CFSTRs either in a growth stage or production stage of a two step fermentation of a recombinant bacterium with an environmentally regulated gene has been investigated. The performance of the multiple CFSTR fermentation at its optimum design is compared to an optimum two stage fermentation. The results show that increasing the number of CFSTRs in the growth stage does not have any effect on the performance of the system, while increasing the number of CFSTRs in the production stage increases the productivity. The increase in the productivity, however, is small compared to the increase in the productivity that occurs with primary products, as reported in the literature. It is also shown that the results can be extended to other recombinant bacteria fermentations.
Modeling cat cracker catalyst demetallization
Authors: Kesavan Padmanaban , Law Victor J. 
Published: March 2009

AbstractVanadium and nickel have been identified as the major poisons that lead to the deactivation of cracking catalysts. These metals can be demetallized by a multistage process involving gas solid non‐catalytic reactions in porous particles. Mathematical models for predicting the removal rate of vanadium when diffusion, reaction, and reaction and diffusion are controlling have been developed. It is generally accepted that vanadium is deposited on specific sites in the interior of the catalyst. This is verified since a diffusion controlled model for the removal of vanadium is in close agreement with experimental results. The parameters of the diffusion controlled model were estimated by constrained nonlinear regression. A total of five lumped mass transfer parameters for vanadium removal were determined using data from a laboratory demetallization unit. These parameters were then used to predict vanadium removal and compared with experiment.
Removal of cadmium from wastewater by enhanced ultrafiltration using surfactants
Authors: Azoug C. , Sadaoui Z. , Charbit F. , Charbit G. 
Published: March 2009

AbstractIn order to recover cadmium ion from wastewater, a process based on enhanced ultrafiltration was finalised. The originality of the solution here proposed lies on the coupled use of ceramic membranes and of a surfactant added to the water to be treated. This paper deals with the study of the influence of experimental conditions upon permeation flux and selectivity of the separation. The process is efficient and flexible since a single stage treatment allows to reduce the concentration of cadmium in the effluent by a factor of about 750; this high performance in selectivity is on a par with high fluxes of permeate (roughly 170 L.h.−1.m−2 at 25°C and 3 × 105 Pa).
Hydrodynamic and mass transfer performance of multiple upcomer extraction trays
Authors: Zhu S. L. , Luo G. S. 
Published: March 2009

AbstractThe multiple upcomer (MU) extraction tray was specifically developed for aromatics extraction processes. Hydro‐dynamic and mass transfer experiments have been carried out with n‐butanol/succinic acid/water as an experimental system in a MU tray extraction column of 0.1 m diameter. The dispersed phase hold‐up, drop size and overall efficiency were measured and the hydrodynamic and mass transfer parameters were correlated. The flooding velocities and the overall efficiency predicted from the correlation for this column agreed well with the experimental data.
Balancing disinfection efficiency and THM formation during chlorination: Theoretical considerations
Authors: Chiang Pen‐Chi , Ko Ya‐Wen , Chang E. E. , Lou Jie‐Chung 
Published: March 2009

AbstractA mathematical model has been developed to predict disinfection efficiency and trihalomethane (THM) formation during water chlorination. The model incorporates chlorine dose, total organic carbon (TOC) concentration, contact time, and geometric configuration of the chlorination chamber. Results indicate that the disinfection efficiency can be better controlled by modifying the geometric configuration of the chlorine contactor. In contrast, geometric configuration plays an insignificant role in controlling THM formation. The application of chlorine at about 1.0 mg/L appears to be the most economic and logical dose for the control of THM formation and the disinfection efficiency of the Liu‐Du water treatment plant under the operational conditions of conventional chlorination practices.
Reformulation of solid propellants and high explosives: An environmentally benign means of demilitarizing explosive ordnance
Authors: Wulfman David S. , Sitton Oliver , Nixon F. Terry , Podzimek Myroslava , Worsey Gillian , Beistel Donald , Worsey Paul , Burch Dan , Johnson Mike 
Published: March 2009

AbstractPolymer Bound Explosives (PBXs) and Class 1.1 Military Propellants have been reformulated for use in the mining industry. There is a minimal waste stream. The explosives are sensitive to initiation by a #8 cap. Impact sensitivities have routinely passed 5 kg meter stimuli, initiation by 50,000 V AC and the BAM friction protocols at 1000 rpm under a 11 kg load for 10 seconds. The explosives were packed into sticks, slurried or used as pourable mixes. VoDs of 2.4 to 6.2 km/s were realized with τ = 0.9 — 1.35 t/m3. The explosives have powers comparable to a range of dynamites. The Beaver Code based upon Lotus 1.2.3 —gTM was developed to predict explosive properties.
Design of a continuous process for the alkaline treatment of xylose into lactic acid
Authors: Raharja S , Rigal L. , Barre L. , Vidal P. F. 
Published: March 2009

AbstractA compact process based on a gas/liquid contactor was designed for the continuous alkaline oxidation of xylose into lactic acid. An experimental design using Doehlert's method was used to study the effect of: i) the NaOH concentration, ii) the xylose concentration, iii) the reaction temperature, and iv) the residence time, on the yield of lactic acid. Results indicate that the conversion of xylose at concentrations between 5‐15% (w/w) is complete and nearly instantaneous at both high temperatures (over 200°C) and high sodium hydroxide concentrations ((> 10% w/w). Yields of lactic acid reaching 50% (with a theoretical yield of 60% (w/w)) were obtained under the most favorable experimental condition suggested by the model developed.
Economic criteria in the design of cascades of CSTR's for the performance of enzyme‐catalyzed reactions
Authors: Malcata F. Xavier 
Published: March 2009

AbstractThe mass balances on substrate in each unit of a series of CSTRs performing an enzyme‐catalyzed reaction described by Michaelis‐Menten kinetics (with parameter Km) are written and the necessary and sufficient condition that must besatisfied by the intermediate concentrations in order to obtain a minimum overall capital investment is found on the assumption that the cost of each reactor unit scales up on its capacity according to a fractional factor exponential rule (with parameter n). The asymptotic situations of pseudo‐zero order and pseudo‐first order behavior are explored. The ratio between consecutive concentrations leading to a minimum overall capital investment decreases as Km decreases at a rate that is slower for higher n, and tends to unity as the pseudo‐first order situation is approached. If fractional values of n are considered, local minima of the capital investment associated with the overall reactor cascade exist only in certain ranges of substrate conversion; below the lower limits of such ranges, the number of reactor units should actually be decreased. A graphical procedure aimed at obtaining the intermediate optimal concentrations is presented.
Evaluation and characterization of vector fluids and peroxides in a process of in situ compatibilization of polyethylene and polystyrene
Authors: Sun Yi‐Jun , Flars Vicki , Baker Warren E. 
Published: March 2009

AbstractAn organic functional silane was found to be the most efficient among several vector fluids in reactive blend compatibilization of the polyethylene (PE) / polystyrene (PS) / peroxide / vector fluid system. This paper involves further analysis of this reactive blending system. Surface tension data was used to calculate spreading coefficients which were compared to the amount of PE‐PS copolymer formed during blending. A good correlation between a computed spreading coefficient and the degree of grafting of PS onto PE was found. The results suggest that the pattern of distribution of the vector fluid in PE / PS blends is the key factor leading to effective results. Furthermore, different peroxides were evaluated in PE / PS blends, in order to determine the dependence of PE / PS interfacial grafting reaction on the structure of the peroxide.
A new correlation for characteristic velocity in rotating disc contactors
Authors: Kalaichelvi Ponnusamy , Murugesan Thanapalan 
Published: March 2009

AbstractOn the basis of present experimental results along with those of available literature (1539 experimental results for 12 systems from 13 different sources) with a wide range of variables, a general correlation for the prediction of characteristic velocity, involving phase flow rates, rotor speed (in terms of Froude number), column geometry and also the physical properties, is presented. The present proposed correlations are more accurate than those previously reported.
Minimum spouting velocity for binary mixture of particles in rectangular spouted beds
Authors: Anabtawi M. Z. 
Published: March 2009

AbstractMinimum spouting velocity data are reported for seven mixtures of polystyrene, spouted with air in three rectangular spouted beds of square cross sectional areas, using nozzles of five sizes. Correlations for minimum spouting velocity in cylindrical columns were investigated for this geometry. A new dimensionless correlation for predicting the minimum spouting velocity is developed.
Nonlinear instabilities of falling films on a heated vertical plane with gas absorption
Authors: Peramanu Subodhsen , Sharma Ashutosh 
Published: March 2009

AbstractThe nonlinear instability and dynamics of nonisothermal falling films with simultaneous absorption from a gas phase are studied theoretically. The study is based on a long wave analysis of equations of motion, energy and mass. The resulting long wave evolution equation describing the film thickness is solved by a Fourier collocation technique. The effects and interactions of flows resulting from gravity, surface tension, thermocapillarity and solutal Marangoni effect are elucidated by considering the following cases: (1) isothermal film; (2) nonisothermal film with purely conductive heat transfer, as well as combined conductive and convective heat transfer; and (3) nonisothermal film with solute absorption. Conditions are identified for equilibration of the wave, wave breaking and for the formation of dry spots. Also, phase diagrams representing the stable and unstable regions are presented for the above cases.
Solid—liquid mass transfer in a shaking vessel for a bioreactor with “current pole”
Authors: Kato Yoshihito , Hiraoka Setsuro , Tada Yutaka , Nomura Toshio 
Published: March 2009

AbstractA shaking vessel with “current pole”, which is a center pole installed at the bottom, had shorter mixing time than a shaking vessel with a cone at the bottom. The mass transfer rate on the suspended particles was also measured in the shaking vessel where ion‐exchange resin beads were used as the suspended particles. The dependence of the solid‐liquid mass transfer coefficient on the circulating frequency changed at the critical circulating frequency for complete suspension NJS. For a circulating frequency higher than NJS, the mass transfer coefficient was correlated with the power consumption per unit volume, regardless of presence or not of the current pole.
Mixing study in an inductive plasma reactor: Comparison between model calculations and experimental results
Authors: Désilets Martin , Davies Benoît , Soucy Gervais , Proulx Pierre 
Published: March 2009

AbstractThis study compares the predictions of a multicomponent reactive model of inductive plasma reactor mixing and experimental data obtained with the enthalpy probe technique. Central injection of two different gases, helium and nitrogen, into the core of an inductive (h.f.) plasma discharge permits us to analyze the influence of the nature of the central gas on the reactor's mixing patterns. This work highlights diffusion in a multicomponent situation. The model considers the dissociation of H2, present in the sheath gas.
Modelling the boiling delay upon venting vapour from a saturated liquid—vapour system
Authors: Lubbe D. S. , Kornelius Gerrit 
Published: March 2009

AbstractA mechanistic model was developed to describe the pressure history when vessels, containing initially saturated liquid, are subjected to sudden depressurisation. A governing equation based on a volume balance was set up. The terms in this equation governing the number of bubbles and the growth rate both before and after departure from the boiling surface are derived. Constants describing the boiling surface are required and derived from experimental work. The model results are compared to experiments at low (< 400 kPa) initial pressures, and reasonable agreement is obtained. The model results obtained for other parameters of practical importance (i.e. swell of the liquid phase and voidage) are shown.
Greffage de molécules à la surface du silicium par voie électrochimique
Authors: Ozanam François , Vieillard Charlotte , Warntjes Marcel , Dubois Thomas , Pauly Maxime , Chazalviel Jean‐Noël 
Published: March 2009

AbstractLa surface hydrogénée du silicium possède des propriétés remarquables, mais une stabilité à l'oxydation insuffisante. Pour y remédier, plusieurs groupes organiques ont été substitués à l'hydrogène de surface. Ces greffages peuvent se faire chimiquement en plusieurs étapes, mais la voie électrochimique permet des réactions directes à partir de la surface hydrogénée. On peut ainsi méthoxyler partiellement la surface du silicium poreux par dissolution anodique contrôlée, mais surtout méthyler sa surface de manière non destructive, avec un rendement de 80% limité seulement par l'encombrement stérique. La surface méthylée du silicium poreux possède une stabilité accrue d'un ordre de grandeur.
Mass transfer parameter estimation using optimization technique: Case study in CO2 absorption with chemical reaction
Authors: Ji Xinsheng , Kritpiphat Weerapong , Aboudheir Ahmed , Tontiwachwuthikul Paitoon 
Published: March 2009

AbstractThis paper proposes a new approach of applying an optimization technique to simultaneously determine a physical liquid—film mass transfer coefficient (KoL) and effective interfacial area (av) from a pilot plant data. The mass transfer mechanism of the CO2‐NaOH system was modeled using the two‐film theory to represent the behaviors of packed absorbers. The model presents an overall absorption rate (Rv) as a function of KoL and av. The optimization algorithm used in this study follows a modified Levenberg‐Marquardt method with a trust region approach. The Rv predictions from the model are in good agreement with the experimental data, with an average error of 6.5%.
Pressure drop prediction in hydraulic transport of bi‐dispersed particles of coal and copper ore in pipeline
Authors: Ghanta Kartik Chandra , Purohit N. K. 
Published: March 2009

AbstractHydraulic transport studies with coal and copper ore have been carried out in a 0.0254 m and a 0.019 m diameter pipeline to observe the effect of solids concentration, surface characteristics and particle size distribution on pressure drop. The coarse coal showed a lower pressure drop than the fines at any velocity of suspension, whereas copper ore, exhibited the opposite trend. It has been observed, that the pressure drop for hydraulic transportation of bi‐dispersed particles is a minimum at certain weight proportions of coarse to fines, as compared to that for the transportation of either of the single size.Based on the experimental results, an empirical expression was developed for the prediction of pressure gradient.
Bubble formation in cocurrently upward flowing liquid
Authors: Terasaka Koichi , Tsuge Hideki , Matsue Hirokazu 
Published: March 2009

AbstractThe effects of liquid velocity, nozzle diameter, gas chamber volume and gas flow rate on volumes, shapes and growth curves of bubbles formed at a nozzle submerged in a cocurrently upward flowing liquid in a bubble column were experimentally investigated. The bubble volume decreases with increasing liquid flow velocity. The effect of liquid flow velocity on the volume of bubble increases with an increase in the gas flow rate. To simulate bubble formation at a nozzle submerged in cocurrently upward flowing liquid, a revised non‐spherical bubble formation model was proposed. Bubble volumes, bubble growth curves and shapes experimentally obtained in this study, as well as in previous experimental studies, are well predicted by the present model.
Hydrodynamic behavior of single particles in a draft‐tube bubble column
Authors: Kikuchi Ken‐Ichi , Takahashi Hiroshi , Sugawara Fumiya 
Published: March 2009

AbstractVelocities of single particles (magnetic tracer particles) were measured in the draft tube region and annular region of a draft‐tube bubble columns by use of the magnet‐detector coil technique. The relative particle to liquid velocity was also obtained. The observed distribution of particle velocity was broader than that of liquid velocity. The relative particle to liquid velocity depended significantly on superficial gas velocity. Those for the draft tube region had minimums with increasing gas velocity, while those for the annular region decreased monotonously. The effective drag coefficients for the particles were correlated with particle Reynolds number and gas holdup.
Influence of particle‐specific gravity and particle shape on the averaged axial velocity of nearly neutrally buoyant particles in horizontal pipes
Authors: Liu S. , Fryer P. J. , Pain J. P. 
Published: March 2009

AbstractThis paper presents an experimental study on the velocities of single, nearly neutrally buoyant particles in water in horizontal flows. Particle specific gravity was found to have a strong effect on the particle velocity. The modified particle Froude number was found to be an effective parameter to reflect the effect of density. A force‐balance model has been developed that includes the effects of particle specific gravity and particle shape.
On a eulerian and lagrangian combined model in dense particle‐laden riser flow
Authors: Fan Jianren , Sun Ping , Ma Yinliang , Cen Kefa 
Published: March 2009

AbstractA new numerical model using both Eulerian and Lagrangian coordinates, and taking account of interparticle interactions, has been developed for the study of hydrodynamic aspects of dense particle‐laden rise flows. A stochastic particle dispersion model has been incorporated in the original model to describe the gas particle turbulent flows. In addition, the collisional interaction between the particles has been modeled using the kinetic theory of granular flows based on the Chapman‐Enskog theory of dense gases. A comparison with the experimental results of Miller and Gidspow (1992) shows reasonably good agreement. The present model may provide a useful approach for predicting the complex hydrodynamic behaviour of fluidized bed systems.
Enlèvement du phosphore des eaux usées par traitement à base de tourbe dopée aux boues rouges
Authors: Roberge Guy , Blaies Jean‐François , Mercier Guy 
Published: March 2009

AbstractL'ajout d'un agent dopant à base d'aluminium et de fer, soit les boues rouges issues de l'extraction de l'alumine de la bauxite, a été testé avec une tourbe horticole commerciale et ce, pour l'épuration d'eaux usées municipales provenant d'un traitement secondaire. Suite à des essais en colonnes, l'efficacité de déphosphatation est passée de 17 et 21% sur la tourbe uniquement à plus de 95% en présence de l'agent dopant. De même, l'utilisation de boues rouges a permis de réduire la concentration de Pt de l'effluent à moins de 0.15 mg/L. L'effet dopant diminuait avec le temps et surtout pro‐portionnellement à la charge hydraulique appliquée. Pour une charge de 30 cm/j j la déphosphatation respectait les recommandations gouvemementales (Pt, dans l'effluent <1 mg/L) et ce, pour une période de 50 jours. Les performances sur les autres paramètres indicateurs classiques tels la DBO5, le DCO et l'enlèvement des coliformes ne furent pas altérés par l'emploi de l'agent dopant.
The achievability of sustainable reporting practices in agriculture
Authors: Williams Belinda R. , Wilmshurst Trevor 
Published: March 2009

AbstractThis research investigates the process of change in moving from a domestic accounting standard, AASB 1037, relating to self‐generating and regenerating assets (SGARAs) to an international standard, AASB 141. It focuses on the achievement (or nonachievement as it may be) of sustainable reporting practices for these agricultural assets. This paper finds that the transition to AASB 141 has allowed firms the discretion to change how they value their agricultural assets in comparison to the domestic standard. Consistency may have been achieved to a limited extent with the introduction of this financial accounting standard but comparability appears not to have been. Further, there is very limited understanding of the reporting of these assets from a user's perspective. It is concluded that this lack of consistency, comparability and understandability will not help achieve sustainability in the reporting practices of agricultural assets. Copyright © 2009 John Wiley & Sons, Ltd and ERP Environment.
Quantitative changes in hippocampal microvasculature of chronically stressed rats: No effect of fluoxetine treatment
Authors: Czéh Boldizsár , Abumaria Nashat , Rygula Rafal , Fuchs Eberhard 
Published: March 2009

AbstractExposure to chronic stress alters the number and morphology of neurons and glia in the hippocampal formation; however, little is known about possible changes in vasculature. Here, we examined the effect of chronic social defeat stress on hippocampal vascular supply in rats. Recent reports document that antidepressant treatment can influence angiogenesis in the hippocampus; therefore, we also studied the effect of antidepressant drug treatment on hippocampal capillarization. Animals were subjected to 5 weeks of daily social defeat by an aggressive conspecific and received concomitant, daily, oral fluoxetine (10 mg/kg) treatment during the last 4 weeks. Rat endothelial cell antigen‐1 (RECA‐1)‐labeling of capillaries and quantitative stereological techniques were used to evaluate the treatment effects on capillary number. Special attention was paid to analysis of the vascular supply of the subgranular zone, which is regarded as an important component of the neurogenic niche for adult hippocampal neurogenesis. Chronic stress significantly decreased the number of microvessels by 30% in all hippocampal subregions, whereas fluoxetine treatment had no influence on capillary number. Furthermore, chronic stress decreased the capillarization of the subgranular zone to a similar extent, indicating that chronic stress affects the vascular niche for adult hippocampal neurogenesis. However, fluoxetine treatment had no impact on capillarization in the subgranular zone. We also detected a decrease in hippocampal volume in the animals as a result of stress, which was mildly altered by fluoxetine treatment. These pronounced changes in vascular supply may explain why the hippocampus is more vulnerable to insults when chronic stress precedes or coincides with other harmful conditions. Reduced microvasculature may also contribute to hippocampal volume decrease in stress‐related disorders. © 2009 Wiley‐Liss, Inc.