bluuebunny/crossref_metadata_2025 huggingface dataset:
Three‐dimensional turbulent flow in agitated vessels with a nonisotropic viscosity turbulence model
Authors: Ju S. Y. , Mulvahill T. M. , Pike R. W.
Published: March 2009

Solutions of the time‐averaged equations of motion with a nonisotropic k‐e model were developed for the three‐dimensional turbulent flow field in turbine stirred tanks. These results were validated with the measurements of three velocity components with a hot wire anemometer and literature data. The nonisotropic turbulence model considered the rotation and curvature effect of the turbulence with a turbulent Richardson number term and accounted for the important three‐dimensional effects through the nonisotropy of the viscosity. Also, it was found that a frequently used isotropic k‐ϵ turbulence model did not describe this three‐dimensional turbulent flow field.
Mathematical modeling of the elutriation of fine materials from rotary kilns
Authors: Tackie E. N. , Watkinson A. P. , Brimacombe J. K.
Published: March 2009

A simple mathematical model has been developed to predict the influence of operating and material variables on the elutriation of fine materials in rotary kilns. The model is based on the mechanism of particle saltation which was observed to be the predominant mode of transport of entrained materials in a previously reported experimental study. For the model knowledge is required of the particle saltation height and the threshold shear stress for particle movement. The model predictions agree well with experimental measurements made in a laboratory rotating cylinder and with the scanty data in the literature. Application of the model to single‐pass industrial kilns such as cement, limestone and alumina kilns is presented.
A new experimental method to specify the diffusing component in a reacting particulate packing
Authors: Hao Yu‐Jun , Tanaka Tatsuo
Published: March 2009

Analysis of the solid‐solid reaction rate has been made, based on the reaction mechanism controlled by the unidirectional diffusion, or by the counter diffusion of the components. To judge which is the diffusing component, the “marker” method has been used so far. However, due to the problems involved the results obtained are sometimes different by different workers even for the same system. The authors propose in this paper a new method to judge the diffusing component in accordance with the difference in the dependence of reaction rate upon the particle size ratio, which was developed in the course of our study on the model of solid‐solid reactions. Examples are demonstrated by using the existing experimental data.
Effect of a row of cylindrical obstructions on mass transfer in creeping flow in a plate‐type membrane separator
Authors: Ishimi Kosaku , Koroyasu Sadatoshi , Ishikawa Haruo , Hikita Haruo
Published: March 2009

Creeping flow across a row of cylinders located between a membrane and a solid plate and mass transfer from the fluid stream through the membrane were studied theoretically. A numerical solution for the product of the friction factor and the Reynolds number was obtained and found to be a function of the dimensionless diameter γ. A numerical solution for the Sherwood number, Sh, was expressed as a function of the Peclet number, Pe, the dimensionless diameter, γ, the number of cylinders, n, and the dimensionless membrane permeability, P. The solution for mass transfer indicated that, with increasing γ, Sh increases at large values of Pe and small values of n, while Sh decreases at small values of Pe and large values of n.
On the representation of pure‐compound saturated (ZV − ZL) values
Authors: Sugie H. , Iwahori Y. , Lu B. C.‐Y.
Published: March 2009

An equation for determining the difference between the compressibility factors of saturated vapor and liquid (ZV ‐ ZL) through cubic equations of state has been developed as a function of reduced vapor pressure Pr, reduced temperature Tr and the critical cohesion parameter Ωac of the chosen equation. The regressed equation has been presented in a polynomial expression of (Pr/Tr) and Ωac for simple non‐iterative calculations.
A model for trickle bed reactors in view of changing gas velocity
Authors: Lekshmi‐Narayanan H. , Pan Chin‐Min , Haure Patricia M. , Hudgins R. R.
Published: March 2009

The trickle‐bed reactor model of Goto and Smith (1978) is modified to account for changes in the gas velocity as a result of the solubility of the active gaseous species in the liquid phase, its rate of uptake by the liquid, and the extent of its participation in the reaction. There appear to be practical cases for which changes in the velocity of the gas phase should not be ignored.
Liquid fuels from canadian peat by the waterloo fast pyrolysis process
Authors: Piskorz J. , Majerski P. , Scott D. S.
Published: March 2009

Two Canadian peats from Quebec were pyrolyzed using the Waterloo Fast Pyrolysis Process (WFPP) technology with the objective of maximizing liquid yields. A young sphagnum peat (Sogovex) gave maximum yields of organic‐liquids (moisture free basis) of 45% to 47% in an optimum range of 450° to 550°C at atmospheric pressure. Char yields decreased from 35% to 26% and gas yields increased from 12% to 17% over this range. The character of the liquid product changed significantly over the optimum temperature range, with the ratio of water‐soluble to water‐insoluble components decreasing from 2.3 to 0.6, with an accompanying decrease in oxygen content.

Pyrolysis tests using an old black peat (Premier) gave similar results, although with some what lower yields of organic liquids and higher char yields.

Upgrading tests on the peat oil done under hydrodeoxygenation conditions in collaboration with Battelle PNWL resulted in a yield of about 33% of the liquid feed as a gasoline‐like liquid.
Managing the water chemistry of a CANDU reactor with an expert system
Authors: Lamirande S. , Roberge P. R.
Published: March 2009

The aim of this project was to capture the expertise of Ontario Hydro in the water chemistry of the heat transport system (HTS) of the CANDU nuclear reactor and transform it into an Expert System prototype. The end product is an Expert System which can realistically diagnose situations and recommend proper courses of action based on the user's water chemistry analysis.
Reactor design from batch data by a direct graphical method
Authors: Lobo Luís S.
Published: March 2009

A graphical method for reactor design is presented which uses the plot of concentration vs. time. This method can be used to compare stirred tank, plug flow and recycle reactors as well as various reactor combinations. With Monod Kinetics the concept of wash‐out can be illustrated. A brief comparison with other graphical methods is made.
Fundamental investigation of plug conveying of cohesionless particles in a vertical pipe (pressure drop and friction of a stationary plug)
Authors: Tsuji Y. , Asano R.
Published: March 2009

A stationary packed bed of cohesionless particles is set up in a vertical pipe for the fundamental study of plug conveying. The effect of flow acceleration or deceleration on the pressure drop of the plug is investigated first. It is found that the pressure drop increases due to the flow acceleration and vice versa. Next, the following three kinds of experiments were made for the study of friction characteristics: 1. Friction between the plug and moving wall without air flow, 2. Friction between the plug and wall with downward air flow, 3. Friction between the plug and wall with upward air flow. The results are compared with the theory established in powder mechanics. The state of stress being of the active or passive case is discussed. Finally the problem of particles raining down from the back of the plug is studied. It is shown that the air velocity necessary to support the particles can be calculated based on a simple analysis of pressure distribution around the particles.
Combustion characteristics of a two‐stage swirl‐flow fluidized bed combustor
Authors: Lee J. K. , Hu C. G. , Shin Y. S. , Chun H. S.
Published: March 2009

In order to investigate the combustion characteristics of a two‐stage swirl‐flow fluidized bed combustor, combustion experiments of low‐grade anthracite coal were performed. Experimental parameters were the fluidizing air velocity, coal feed rates, bed temperature, stoichiometric air ratio, swirl nozzle diameter and rotational diameter. The experimental results showed that, due to the swirl flow, the elutriation rates of fines were lower than those of the single‐stage fluidized bed combustor. The combustible contents of the ash in the outflow streams were also reduced. Therefore, the combustion efficiency of the two‐stage swirl‐flow fluidized bed combustor was 20% greater than that of the single‐stage fluidized bed combustor under the same operating conditions.
Epoxidation of oleic acid with oxygen in the presence of benzaldehyde using heterogenized homogeneous co‐type ion‐exchange membrane as catalyst
Authors: Kuo Ming‐Chao , Chou Tse‐Chuan
Published: March 2009

The epoxidation of oleic acid with oxygen in the presence of benzaldehyde to produce epoxidized oleic acid using a Co‐type ion‐exchange membrane as catalyst was carried out. No leakage of cobalt ion was found during the experimental runs. The epoxidized oleic acid was formed by a series of free radical reactions. Experimental results show that at 70% conversion of oleic acid, 60% of the total theoretical epoxidized oleic acid was obtained, illustrating the high selectivity (86%). The rate‐determining steps were experimentally identified and the formation rate of epoxidized oleic acid was found.
Electrosynthesis of sodium dithionite in a trickle‐bed reactor
Authors: Oloman Colin , Lee Ben , Leyten Wayne
Published: March 2009

Sodium dithionite was generated by electroreduction of sulphur dioxide on a graphite fibre mat cathode in a continuous ‘flow‐by’ trickle‐bed electrochemical reactor. Reactor performance was measured with respect to variation of the feed catholyte NaOH concentration [0.5‐1.0 mol/L], feed gas SO2 concentration [4‐40 vol%], product catholyte pH [2.4‐12.0] and applied current [10‐50 A (0.4‐2.0 kA/m2)]. Product catholyte temperature was in the range 18 to 30°C. With product catholyte pH between 2.4 and 6.9, dithionite was generated at current efficiency from 42 to 100%, concentration from 0.05 to 0.78 mol/L, yield from SO2 up to 69% and specific energy from about 2 to 5 kWh/kg Na2S2O4. Current efficiency fell with increasing current and rose with increasing gas load. High levels of thiosulphate [0.07‐0.3 mol/L] and sulphide [0.01‐0.13 mol/L] measured in the product catholyte would compromise the use of this process in commercial applications such as brightening wood pulp.
Estimation of parameters in monte carlo modelling
Authors: Duever T. A. , Reilly P. M.
Published: March 2009

This paper presents a general method for estimating model parameters from experimental data when the model relating the parameters and input variables to the output responses is a Monte Carlo simulation. From a statistical point of view a Bayesian approach is used in which the distribution of the parameters is handled in discretized form as elements of an array in computer storage. The stochastic nature of the Monte Carlo model allows only an estimate of the distribution to be calculated from which the true distribution must then be estimated. For this purpose an exponentiated polynomial function has been found to be useful. The method provides point estimates as well as joint probability regions. Marginal distributions and distributions of functions of the parameters can also be handled. The motivation for exploring this alternative parameter estimation technique comes from the recognition that for some systems, particularly when the underlying process is stochastic in nature, Monte Carlo simulation often is the most suitable way of modelling. As such, the Monte Carlo approach increases the range of problems which can be handled by mathematical modelling.

The technique is applied to the modelling of binary copolymerization. Two models, the Mayo‐Lewis and the Penultimate Group Effects models, are considered and a method for discriminating between these models in the light of sequence distribution data is proposed.
A new approach using canonical correlation combined with advanced analytical techniques to simulate a chemical process
Authors: Chakravarty T. , Khan M. Rashid , Meuzelaar H. L. C.
Published: March 2009

An important requirement for mathematical modeling of chemical reactors is a means for simulation of the underlying chemical process. The goal of any reactor simulation is to enable prediction of the yield and composition of the products. This study shows the potential application of canonical correlation in combination with advanced analytical techniques (such as GC‐MS, FTIR, Py‐MS) toward modeling and prediction in chemical reactors. The mathematical description presented allows generalization of this approach.
The error‐in‐variables model applied to parameter estimation when the error covariance matrix is unknown
Authors: Keeler Scott E. , Reilly Park M.
Published: March 2009

This paper presents a method for Error‐in‐Variables Model (EVM) analysis when there is no prior knowledge of the error structure, but there is replication in the data. The method is presented, with examples, for cases where the error structure varies among the data, and for cases where the error structure is constant over all the data. The minimum amount of replication needed is discussed and posterior probability density functions are developed for the parameters. The results are an extension of the work of previous authors.
Statistical process control procedures for correlated observations
Authors: Harris Thomas J. , Ross William H.
Published: March 2009

Measurements from industrial processes are often serially correlated. The impact of this correlation on the performance of the cumulative sum and exponentially weighted moving average charting techniques is investigated in this paper. It is shown that serious errors concerning the “state of statistical process control” may result if the correlation structure of the observations is not taken into account. The use of time series methods for coping with serially correlated observations is outlined. Paper basis weight measurements are used to illustrate the time series methodology.
Friction factor for gas‐non‐newtonian liquid flow in horizontal bends
Authors: Das S. K. , Biswas M. N. , Mitra A. K.
Published: March 2009

Experimental investigations have been carried out to evaluate the two‐phase pressure drop data across different types of horizontal bends for gas‐non‐Newtonian liquid flow. The non‐Newtonian liquids used were different concentrations of the sodium salt of carboxymethyl cellulose (SCMC) which behaved like pseudoplastic fluids. Correlations have been developed to predict the gas‐non‐Newtonian liquid two‐phase friction factor as a function of various physical and dynamic parameters of the system. Statistical analysis of the correlations suggests that the correlations are of acceptable accuracy.
A study of the deposition of silt onto the surface of type 304 stainless steel
Authors: Turner C. W. , Lister D. H.
Published: March 2009

The deposition rate of Lake Ontario silt onto type 304 stainless steel at a fluid velocity of 1.05 m/s is given by:

N = 2.1 × 10−5 exp (‐E/RT) Cb p.

where E = 25.3 kJ/mol. Both the magnitude and the temperature dependence of the deposition rate is consistent with deposition that is surface rather than transport limited. The release rates were small compared to the deposition rates and independent of the surface temperature. Only particles less than 5 μm were found in the deposits at 1.05 m/s, even though particles up to 25 μm were in the flowing silt suspension. The maximum particle size in the deposit decreased with increasing deposition velocity.
Motion of pulp fibre suspensions in rotary devices
Authors: Bennington C. P. J. , Kerekes R. J. , Grace J. R.
Published: March 2009

Suspensions of semi‐bleached kraft pulp at low and medium mass concentrations were sheared in a rotary shear tester at angular velocities up to 524 rad/s (5000 rpm). The use of baffled housings, with rotors having lugs, imposed shear within the body of the suspensions and prevented slip at the vessel walls. The torque was measured as a function of angular velocity, and high speed photographs were taken through a transparent plate to aid in interpretation of the findings. The torque vs. angular velocity curves and flow phenomena were found to depend on the mass concentration of the suspension, the gap width between the rotor and housing, and the air content of the suspension. With little gas present, the flow initially involved tangential flow in an active cavity whose radial extent increased with increasing angular velocity. When the flow reached the outer baffles, a marked flow transition occurred, probably explaining what has been called “fluidization” by Gullichsen and Harkonen (1981). As the gas content of the suspension increased, the gas congregated around the rotor, impeding the transfer of momentum to the suspension. The apparent viscosity of a 10% by mass suspension was of the order of 16 Pa · s under the test conditions.
Hydrodynamic entrance lengths of non‐newtonian laminar falling films
Authors: Li Ruokang
Published: March 2009

The Carreau viscosity model of the shear deformation is used to determine the hydrodynamic entrance length for falling liquid films emerging from a flat slit and flowing in a laminar fashion along an inclined flat plate. The present work enables the entrance‐length problem to be treated in a general form by choosing different values of the two parameters in the model. It is found that a significant difference exists between predicted results based on the power law model and the Carreau model when the fluid is pseudoplastic and the flow is decelerating.
Prediction of the maximum spoutable bed height in spout‐fluid beds
Authors: Grbavčić Ž. B. , Hadžismajlović Dž. E. , Garić R. V. , Vuković D. V. , Littman H.
Published: March 2009

A model for predicting the ratio of the maximum spoutable bed height in a spout‐fluid bed to the maximum spoutable bed height in a spouted bed is presented and experimentally verified. The model is a further extension of the basic Mamuro and Hattori force balance model. The ratio HmSF/Hm is found to be a function of the external annular fluid flowrate and a parameter C, which is the ratio of fluid velocity at the top of the annulus to that at minimum fluidization. C = 0.935 gives a best fit of our data.
Growth characteristics of a Bombyx mori insect cell line in stationary and suspension cultures
Authors: Stavroulakis Dimitrios A. , Kalogerakis Nicolas , Behie Leo A. , Iatrou Kostas
Published: March 2009

The growth characteristics of the BM‐5 insect cell line of Bombyx mori (silkworm) have been experimentally investigated in order to develop optimal growth protocols when these cells are used to produce large quantities of biopesticides or human proteins by recombinant baculoviruses. Experiments were performed in 2 mL wells and 200 mL spinner flasks. Spinner flasks were operated at 80 rpm with 0.3% methyl cellulose (MCL) added to the medium in order to protect the cells from liquid shear stress. In addition to the effect of agitation rate and amount of MCL added to the medium, the cell response during the adaptation to growth in suspension from stationary cultures is reported. Exposure of the cells to varying nutrient and metabolite concentrations is accomplished through batch and repeated‐batch modes in 2 mL wells. The results imply that glutamine is a limiting nutrient and lactate has an inhibitory effect on cell growth. Ammonia depletion from the medium was accompanied by uric acid accumulation, suggesting that ammonia is converted to this metabolic product by the “uricotelic” and “nucleicolytic” metabolic pathways.
Control of mass transfer and hydrodynamic holdup in a karr solvent extraction column
Authors: Camurdan M. C. , Taylor P. A. , Baird M. H. I.
Published: March 2009

This paper reports an experimental application of multiloop control to a Karr solvent extraction column (a reciprocating plate column). The control objective was to keep the extract outlet concentration above some minimum level and to maintain a high value of dispersed phase holdup while keeping away from the flooding point. Transfer function models were identified from step tests about a nominal operating point and various interaction/operability analysis techniques were used to synthesize a control scheme. The control implemented in this study was a model inversion based scheme in which the extract outlet concentration was controlled by manipulating the continuous phase superficial velocity and the dispersed phase holdup was controlled by manipulating the frequency of reciprocation. Both servomechanism and regulatory responses are presented. A variable dead time Dahlin controller was used to control the extract outlet concentration and a Clarke‐Gawthrop self tuning regulator was used to control the dispersed phase holdup. This multiloop control scheme is compared to single loop control of the extract outlet concentration.
Performance of two heat transfer fouling probes for various fluids
Authors: Steinhagen H. Müller , Branch C. A.
Published: March 2009

The predictions of two commonly used fouling monitoring devices, namely a heated rod in an annulus and a coiled wire in cross‐flow are compared. As fouling fluids, heptane with dissolved styrene (to simulate chemical reaction fouling), heptane with suspended particles (to simulate particulate fouling) and Kraft pulp black liquor (where both the above fouling mechanisms may occur) have been used.
Reactive distillation of pyridine mixtures with an organic acid. I. Determination of the reactive distillation equilibrium
Authors: Duprat Françoise , Gau Georges
Published: March 2009

The reactive distillation equilibrium has been experimentally determined by chromatographic analysis of the vapor phase for various mixtures of two pyridines plus an organic acid in stoichiometric deficiency in an organic solvent. Protonation of pyridines by a weak acid seems to involve ion pair formation, while protonation by a strong acid seems to result in free ion formation, and may involve a small quantity of triple molecule ions (two pyridine molecules for one acid molecule). Steric effects are not significant in such ion formation and the chemical equilibrium constant can be predicted from the pyridine pKa difference using a linear relationship. Despite the possible formation of triple molecule ions, the reactive distillation equilibrium at constant acid quantity can be reasonably well described as an ideal liquid‐vapor equilibrium combined with an ideal chemical equilibrium. However, the increase of the chemical equilibrium constant with the acid quantity should be taken into account in a more refined model.
Mecanismes de colmatage et performances comparées de quatre membranes d'alumine: Cas de l'ultrafiltration de gelatine
Authors: Freund Ph. , Rios G. M.
Published: March 2009

Dans cet article, les performances de quatre membranes tubulaires d'alumine SCT de diamètres de pores différents (0.2, 0.8, 1.4 et 2.0 μm respectivement) ont été étudiées pour différentes conditions de pression, vitesse tangentielle et concentration de fluide. L'analyse des résultats obtenus (débits de perméation au solvant pur des membranes propres ou conditionnées, débits d'ultrafiltration, taux de rétention des espèces protéiques) au moyen de modèles simples (théorie de la filtration, théorie du film) amène les auteurs à émettre des hypothèses originales quant au mode de fonctionnement particulier de chaque élément filtrant. En particulier, il est établi que les mécanismes de mise en place et le type du colmatage évoluent fortement d'une membrane à l'autre. Enfin, les auteurs concluent que, pour les conditions expéri‐mentales choisies, c'est la membrane de 0.2 μm qui en règie générate permet d'atteindre les débits d'ultrafiltration et taux de rétention maxima.
Enzymatic production of l‐alanine from malic acid with malic enzyme and alanine dehydrogenase with coenzyme regeneration
Authors: Suye Shin‐Ichiro , Kawagoe Mikio , Inuta Shusei
Published: March 2009

An enzyme reaction system with coenzyme regeneration was investigated for L‐alanine production. Alanine dehyrogenase L‐alanine: NAD+ oxidoreductase (EC 1.4.1.1)] from Corynebacterium flaccumfaciens AHU‐1622 was used as the catalyst for reductive amination of pyruvate to L‐alanine. NAD‐ and NADP‐linked malic enzyme [L‐malate: NAD(P)+ oxidoreductase (EC 1.1.1.39)] from Pseudomonas diminuta IFO‐13182 was used for the regeneration of NADH. Optimum conditions for L‐alanine production were determined, including L‐malic acid concentration, MgCl2 concentration and pH. Under suitable conditions, the conversion of L‐malic acid to L‐alanine reached 95% after 72 h of incubation at 30°C, yielding 106 mol/m3 of L‐alanine. The L‐alanine produced was purified in crystal form; its purity was 99.4%, based on HPLC analysis.
A priori modelling of an adiabatic spouted bed catalytic reactor
Authors: Hook Bruce D. , Littman Howard , Morgan Morris H. , Arkun Yaman
Published: March 2009

An a priori reactor model for an adiabatic spouted bed reactor has been developed. This model uses first‐principles mass and energy balances to predict the concentration and temperature profiles in the spout, annulus and fountain regions of the reactor. The particle circulation and voidage profiles in the spout are calculated using previously developed analytical techniques. Particle circulation patterns in the annulus are determined by a minimum path‐length analysis. The spout and fountain are shown to contribute significantly to the overall conversion in the bed. Predicted and experimental conversions at flowrates up to 1.2Ums show that extension of the fountain reaction zone and increased particle circulation with increasing inlet flow makes up for the higher average voidage in the spout and fountain. Experimental data confirm the calculated results for a stably spouting bed with CO oxidation over a Co3O4/αAl2O3 catalyst. The effects of flowrate and inlet reactant concentration are confirmed.
Role of sparger design on gas dispersion in mechanically agitated gas‐liquid contactors
Authors: Rewatkar V. B. , Joshi J. B.
Published: March 2009

Critical impeller speeds for gas dispersion and gas recirculation were measured in 0.57, 1.0 and 1.5 m i.d. vessels, using visual observations, measurements of power consumption and liquid‐phase mixing time. A pitched blade down‐flow turbine impeller (PTD) was used. Design parameters of the PTD impeller such as diameter (0.22Tto 0.57T), blade width (0.25D to 0.4D) and blade thickness (2.8, 4.3 and 6.4 mm) were studied. The effect of sparger type and geometry on NCD has been investigated. For this purpose, pipe, ring, conical and concentric ring spargers were employed. Design details of the ring sparger such as ring diameter, number of holes and hole size were also studied in detail. The sparger location with respect to the impeller was found to be the most important parameter. Correlations have been developed for NCD and NCR.
Solubility of methane in glycols at elevated pressures
Authors: Jou F.‐Y. , Otto F. D. , Mather A. E.
Published: March 2009

The solubility of methane in ethylene glycol and in diethylene glycol has been determined at temperatures in the range 25 to 125 °C at pressures up to 20.4 MPa. The experimental results were correlated by the Peng‐Robinson (1976) equation of state, and interaction parameters have been obtained for these systems. Henry's constants were derived for comparison with data from the literature.
Corréation entre la stabilité colloïdale de la matière première et le degré de dispersion du noir de carbone
Authors: Chaala et A. , Benallal B.
Published: March 2009

The evolution of carbon black technology allows, at present, various hydrocarbon products as fillers in complex mixtures.

The fillers investigated in this work are made of a blend of five products from different origins.

The objective of this work is the study of the correlation between the colloidal stability of the filler and the quality of the carbon black, as well as the relation between the degree of dispersity of the carbon black and the resin tensile strength.
Polymer reaction engineering: From reaction kinetics to polymer reactor control
Authors: Penlidis A.
Published: March 2009

Polymer reaction engineering is a relatively “young”, very broad, multidisciplinary, rapidly developing field. It is the combination of polymer science, chemistry and technology with process engineering principles. The outcome of this high degree of synergism has evolved over the last fifteen or so years towards an area that includes any or all of the following: polymerization and post‐polymerization (chemical modification) reaction kinetics; mathematical modelling and process simulation; polymer reactor design and scale‐up; sensor development and process monitoring; and polymer reactor optimization, state estimation and computer control.

This article will attempt to give an overview of the results obtained in our laboratory over the last seven years from systematic studies of polymer reaction engineering and polymer production technology problems. These problems cover all aspects of polymer reaction engineering mentioned above. Going from fundamentals to practice, the basic premise of the article is that only by adopting a holistic approach can one devise effective strategies in order to achieve the final objective of more efficient polymer reactor design and control, and hence improved production systems of polymeric materials.
Fixed‐Bed adsorber dynamics in binary physisorption‐diffusion
Authors: Gomes Vincent G. , Fuller O. Maynard
Published: March 2009

Reactions carried out under conditions close to the equilibrium vapour pressure of the participating species involve physisorption on the catalyst surface. Such conditions are encountered for propene metathesis over rhenium oxide/γ‐alumina catalyst at room temperature. The sorption‐diffusion effects were tested by excluding effects due to reaction. Single‐component sorption characteristics were determined by steady‐state experiments. The model equations comprising several differential and nonlinear algebraic equations were solved by orthogonal collocation within the method of lines. The model predictions were tested against transient experiments performed in a gradientless, internal recirculation reactor.
A study of solid behavior in spouted beds using 3‐D particle tracking
Authors: Roy David , Larachi Faiçal , Legros Robert , Chaouki Jamal
Published: March 2009

A non‐invasive γ‐ray emission system, employing eight NaI detectors, has been developed to follow the motion of a single radioactive particle in a three‐dimensional spouted bed reactor. The count‐rates measured simultaneously by the detectors are converted into tracer coordinates (x, y, z) using a pre‐established calibration model which accounts for every physical and geometrical aspects involved in the spouting facility. Typically four hundred thousands successive coordinates, obtained over 3.5 hours of particle tracking, are used for determining the average particle velocity field and other hydrodynamic quantities such as the cycle time distribution, the spout shape and the solid exchange distribution at the spout boundary, which could not be evaluated accurately using any available techniques.
Transient forced convection in the entrance region of porous concentric annuli
Authors: Al‐Nimr M. A. , Aldoss T. K. , Naji M. I.
Published: March 2009

The problem of transient laminar forced convection in the entrance region of a porous concentric annulus with developing thermal boundary layer is solved numerically by the finite difference technique. The hydrodynamic behaviour of the flow is assumed to be steady and fully developed, and both Darcian and non‐Darcian effects on the flow are considered.
Process for production of arachidonic acid concentrate by a strain of mortierella alpina
Authors: Li Zu‐Yi , Lu Yingyin , Yadwad V. B. , Ward O. P.
Published: March 2009

Various Mortierella alpina fungi were screened for their capacities to produce arachidonic acid. A strain of M. alpina was found to show the highest productivity. Arachidonic acid content of biomass and overall yield per litre of culture was highest in soya flour supplemented medium which produced dispersed mycelium. When the glucose concentration in the medium was varied from 30 to 100 g/L, biomass, lipid, arachidonic acid content of biomass and arachidonic acid yield increased with increasing glucose concentration. Several natural oils, when added to the growth medium, stimulated arachidonic acid production. After fermentation in a 20‐L fermenter under optimal culture conditions, the arachidonic acid yield was 5.3 g/L, representing 34.2% w/w of total fatty acids and 13.7% w/w of biomass. An extract containing 72.5% w/w arachidonic acid was prepared from the recovered mycelium.
Kinetic modeling of the hydrolysis of carbon disulfide catalyzed by either titania or alumina
Authors: Tong S. , Dalla Lana I. G. , Chuang K. T.
Published: March 2009

The reaction rates for the hydrolysis of CS2on either alumina (Kaiser 201) or titania (CRS 31) were measured at 150 kPa and from 270 to 330°C using a laboratory Berty reactor over ranges of water concentration (2–12 mol%) and CS2concentration (0.5–2 mol%). Four mechanism‐related model functions were tested in the search for the best‐fitting rate function by using non‐linear regression techniques. The results show that the Eley‐Rideal rate function best‐fitted the kinetics using either Kaiser 201 or CRS 31 with different parameters. The kinetic parameters obtained confirm that CRS 31 appears to have the higher activity of the two catalysts for CS2hydrolysis. The strong adsorption of water vapor on each of the two catalysts studied inhibits the hydrolysis rate and affords an effective reaction order close to zero for H2O, possibly by saturating the catalysis surface and reducing the fraction of catalyst surface available for CS2and COS adsorption.
Dynamical model for indoor radon concentration monitoring
Authors: Brabec Marek , Jílek Karel
Published: March 2009

In this paper, we will deal with interesting example of natural risk modeling – namely of indoor radon concentration, needed for proper exposure assessment and appreciation of quality of preventive measures taken. First, we will illustrate, how the traditional view based on fixed (i.e., time‐invariant) coefficient models can be misleading. Then we formulate a flexible (nonparametric) regression dynamic model offering a doable alternative. Situation is not entirely standard here, as the smoothed and weight‐giving variables are different. Nevertheless, estimation for our local regression formulation is easily doable even for rather large data via extension of standard local smoothing that we describe. We illustrate on data coming from a rare intensive measurement campaign in an occupied house with simultaneous measurements taken in different rooms. Our model has nice physical interpretation of its parts. We also illustrate how even such a simple model can produce behavior that throws some light on radon experts' discussions about natural radon concentration circadial movement phase. This is because our model acts as a linear but time‐varying filter that can change not only amplitude but also phase between different rooms of the same house, suggesting that there might not be a universal phase of (e.g., daily) radon variation. Instead, the phase might depend on how close a particular indoor location is to the radon sources. Finally, we present some ideas about how our model can be expanded in future to cover more complicated situations and settings. Copyright © 2009 John Wiley & Sons, Ltd.
Nasal tip augmentation in Asians using autogenous cartilage
Authors: Jin Hong‐Ryul , Won Tae‐Bin
Published: March 2009

Objectives

To present surgical techniques and results of nasal tip augmentation in Asian noses and suggest a surgical algorithm for a successful outcome.

Study Design

A case series at a tertiary hospital.

Subjects and Methods

One hundred and seven patients who had undergone nasal tip augmentation using autogenous cartilages from January 2005 to December 2006 were enrolled in the study. Medical records, graphic operation records, and standardized patient photographs were retrospectively reviewed. Initial diagnoses, techniques for tip augmentation, combined tip surgery techniques, surgical results, and complications were analyzed.

Results

Initial diagnoses included deviated nose, hump nose, saddle nose, low‐profile nose, and short nose. An external approach was used in 74 percent and intranasal approach in 26 percent. For augmentation of the tip projection, onlay grafts with or without columellar strut (59%) and septal extension grafts with or without onlay grafts (25%) were the most commonly used techniques. Ninety‐three percent of the patients were satisfied with the results. Complications included tip deviation and visible tip graft.

Conclusion

Augmentation of nasal tip projection in Asians can be effectively performed using autogenous cartilage. Onlay graft and septal extension graft are two important techniques for a successful outcome.
Humanitarian otologic missions: Long‐term surgical results
Authors: Horlbeck Drew , Boston Mark , Balough Ben , Sierra Ben , Saenz Guillermo , Heinichen Julio , Duckworth Laurie
Published: March 2009

Objective

The purpose of this study was to determine the efficacy of treating chronic ear disease by performing a single surgical intervention in the austere environment of a developing nation.

Subjects and Methods

Data were collected from retrospective chart reviews on 121 patients who underwent surgical treatment of chronic ear disease during humanitarian surgical missions in South and Central America. Surgical outcomes and clinical course were assessed at 10 to 12 months after the initial surgery.

Results

A total of 117 patients were included in the study. Follow‐up records were available for 75 patients (64%). A total of 20 surgeries were performed for dry perforations (group 1), 30 for chronically draining ears (group 2), and 25 for cholesteatomas (group 3). Surgical success was determined as 60 percent, 74 percent, and 92 percent for groups 1, 2, and 3, respectively.

Conclusions

Surgical results during international otologic outreach missions to developing nations fall within the results expected in developed nations.
Airway management in pediatric epiglottitis: A national perspective
Authors: Acevedo Jason L. , Lander Lina , Choi Sukgi , Shah Rahul K.
Published: March 2009

Objectives

The purpose of this study was to describe current demographics and resource utilization in the treatment of pediatric epiglottitis.

Study Design

Case series from a national database.

Subjects and Methods

The Kids' Inpatient Database was systematically searched to extract patients under 19 years old admitted with a diagnosis of epiglottitis and undergoing an airway intervention.

Results

Three hundred forty‐two sampled admissions were for epiglottitis; 40 of these patients were under the age of 19 and had an airway intervention (intubation or tracheotomy). On average, patients were 4.3 years old (SD = 6.0 years). The average length of stay was 15.6 days (SD = 33.9 and range = 0–199) with average total charges of $74,931 (SD = $163,387, range = $3342‐$938,512). Multivariate analysis revealed that admission to a children's facility, admission other than via the emergency room, and nonemergent admission were associated with increased total charges. Twenty‐two states reported an admission for pediatric epiglottitis that required airway intervention.

Conclusions

In our sample, only 40 patients were identified who were under the age of 19 years and required an airway intervention for the treatment of epiglottitis. Epiglottitis is a rare, expensive, and protracted disease to treat in the postvaccine era. The unique nature of this disease has implications for training future surgeons on proper management of this potentially fatal disease.
Cost of compliance with daily recommended values of micronutrients among a cohort of Spanish university graduates: the SUN (Seguimiento Universidad de Navarra) Study
Authors: Lopez Celeste N , Martinez-Gonzalez Miguel A , Alonso Alvaro , Sanchez-Villegas Almudena , de la Fuente Carmen , Bes-Rastrollo Maira
Published: March 2009

Objective

Previous studies have shown that highly nutritious diets are more costly, but to date there has been no evaluation of the costs associated with failing to meet micronutrient recommendations in a Spanish population.

Design, setting and subjects

We examined whether daily food consumption costs (classified in quintiles) were associated with failing to meet at least three daily nutritional recommendations out of twenty (including fibre and nineteen micronutrients) in a cross-sectional analysis of baseline data of a cohort of 17 197 Spanish university graduates. Micronutrients and fibre intake were assessed with a validated 136-item FFQ. Average cost of food was calculated from official Spanish government data.

Results and conclusions

As participants presented higher dietary energy cost from their diet, their intake of micronutrients increased significantly. Low dietary energy cost was associated with a higher likelihood of failing to meet three or more recommendations (Pfor trend <0·001 across quintiles of dietary cost), the association being stronger among female than male participants (Pfor interaction between sex and quintile of dietary energy cost <0·001).
Connexin43 phosphorylation: structural changes and biological effects
Authors: Solan Joell L. , Lampe Paul D.
Published: March 2009

Vertebrate gap junctions, composed of proteins from the connexin gene family, play critical roles in embryonic development, co-ordinated contraction of excitable cells, tissue homoeostasis, normal cell growth and differentiation. Phosphorylation of connexin43, the most abundant and ubiquitously expressed connexin, has been implicated in the regulation of gap junctional communication at several stages of the connexin ‘life cycle’, including hemichannel oligomerization, export of the protein to the plasma membrane, hemichannel activity, gap junction assembly, gap junction channel gating and connexin degradation. Consistent with a short (1–5 h) protein half-life, connexin43 phosphorylation is dynamic and changes in response to activation of many different kinases. The present review assesses our current understanding of the effects of phosphorylation on connexin43 structure and function that in turn regulate gap junction biology, with an emphasis on events occurring in heart and skin.
Ecosystem science: toward a new paradigm for managing Australia's inland aquatic ecosystems
Authors: Likens Gene E. , Walker Keith F. , Davies Peter E. , Brookes Justin , Olley Jon , Young William J. , Thoms Martin C. , Lake P. Sam , Gawne Ben , Davis Jenny , Arthington Angela H. , Thompson Ross , Oliver Rod L.
Published: March 2009

Freshwater ecosystems are a foundation of our social, cultural, spiritual and economic well being. The degraded condition of many of Australia’s river ecosystems is testament to our failure to manage these resources wisely. Ecosystem science involves the holistic study of complex biophysical systems to understand the drivers that influence ecological pattern and process. Ecosystem science should underpin both water management and policy. Our understanding of aquatic ecosystems lags behind the increasing problems caused by past land and water management. Current post-graduate training programmes will not provide the aquatic ecosystem scientists needed by government and management agencies to prevent further degradation. We advocate new initiatives to capture the skills, knowledge and innovation of our research community by engaging scientists and managers in large-scale, long-term ecosystem science programmes across Australia and to integrate these programmes with community aspirations, policy, planning and management. We call on management agencies to increase their support for and uptake and use of ecosystem science. We also advocate establishment of national archives for long-term ecologically-relevant data and samples, and clear custodial arrangements to protect, update and facilitate knowledge-transfer. These initiatives need to be supported by more extensive, better-funded post-graduate and post-doctoral programmes in ecosystem science and management.
Neuropilin 1 signaling guides neural crest cells to coordinate pathway choice with cell specification
Authors: Schwarz Quenten , Maden Charlotte Henrietta , Vieira Joaquim M. , Ruhrberg Christiana
Published: March 2009

Neural crest cells (NCCs) are highly motile embryonic stem cells that delaminate from the neuroectoderm early during vertebrate embryogenesis and differentiate at defined target sites into various essential cell types. To reach their targets, NCCs follow 1 of 3 sequential pathways that correlate with NCC fate. The firstborn NCCs travel ventrally alongside intersomitic blood vessels to form sympathetic neuronal progenitors near the dorsal aorta, while the lastborn NCCs migrate superficially beneath the epidermis to give rise to melanocytes. Yet, most NCCs enter the somites to form the intermediate wave that gives rise to sympathetic and sensory neurons. Here we show that the repulsive guidance cue SEMA3A and its receptor neuropilin 1 (NRP1) are essential to direct the intermediate wave NCC precursors of peripheral neurons from a default pathway alongside intersomitic blood vessels into the anterior sclerotome. Thus, loss of function for either gene caused excessive intersomitic NCC migration, and this led to ectopic neuronal differentiation along both the anteroposterior and dorsoventral axes of the trunk. The choice of migratory pathway did not affect the specification of NCCs, as they retained their commitment to differentiate into sympathetic or sensory neurons, even when they migrated on an ectopic dorsolateral path that is normally taken by melanocyte precursors. We conclude that NRP1 signaling coordinates pathway choice with NCC fate and therefore confines neuronal differentiation to appropriate locations.
Molecular characterization of swine leucocyte antigen class I genes in outbred pig populations
Authors: Ho C.‐S. , Lunney J. K. , Franzo‐Romain M. H. , Martens G. W. , Lee Y.‐J. , Lee J.‐H. , Wysocki M. , Rowland R. R. R. , Smith D. M.
Published: March 2009

The highly polymorphicswine leucocyte antigen(SLA) genes are one of the most important determinants in swine immune responses to infectious diseases, vaccines, and in transplantation success. Study of SLA influence requires accurate and effective typing methods. We developed a simple and rapid method to type alleles at the three classical SLA class I loci (SLA‐1,SLA‐3andSLA‐2) using the PCR‐sequence‐specific primer (PCR‐SSP) strategy. This typing system relies on 47 discriminatory PCR primer pairs designed to amplify the SLA class I alleles by groups that have similar sequence motifs. We applied this low‐resolution group‐specific typing method to characterize the SLA class I alleles present in three outbred pig populations (n = 202). Alleles from 24 class I allele groups corresponding to 56 class I genotypes were detected. We also identified 23 low‐resolution SLA class I haplotypes in these pigs and found haplotypes Lr‐1.0 (SLA‐1*01XX‐SLA‐3*01XX‐SLA‐2*01XX) and Lr‐4.0 (SLA‐1*04XX‐SLA‐3*04XX‐SLA‐2*04XX) in all three pig populations with a high prevalence. Over 80% of the pigs examined (n = 162) were found to bear at least one of these haplotypes, resulting in a combined haplotype frequency of nearly 50%. This PCR‐SSP‐based typing system demonstrates a reliable and unambiguous detection of SLA class I alleles, and can be used to effectively investigate the SLA diversity in outbred pig populations. It will help to identify the role of SLA antigens in disease‐resistant pigs and may facilitate the development of effective vaccines.