bluuebunny/crossref_metadata_2025 huggingface dataset:
Mixing characteristics and gas hold‐up of a bubble column
Authors: Guy C. , Carreau P. J. , Paris J.
Published: March 2009

The hydrodynamic behavior of a bubble column has been studied for various Newtonian and non‐Newtonian liquids (water, glycerol, carboxymethylcellulose and polyacrylamide solutions). The mixing time, the power consumption, the circulation time and the gas hold‐up have been measured in a cylindrical column (diameter: 0.254 m, height: 0.9 m) for three air sparger plates with different numbers and distributions of 1 mm diameter orifices. It is shown that the mixing efficiency decreases as the viscosity or the shear‐thinning and elastic properties of the liquid increase. The viscosity of the liquid has little influence on the gas hold‐up which is, however, strongly affected by the sparger plate characteristics and increases as the liquid phase becomes more elastic. A model for predicting gas hold‐up is proposed.
Measuring and modelling lateral solid mixing in a three‐dimensional batch gas—solid fluidized bed reactor
Authors: Berruti F. , Scott D. S. , Rhodes E.
Published: March 2009

A 0.27 m diameter fluidized bed reactor has been designed to allow experimental measurement of the axial and radial mixing behaviour of the solids.

A unique method has been developed which permits the continuous determination of solid tracer concentration with time at different radial and axial positions within the fluidized bed.

Solids mixing has been described by a model in which vertical mixing is instantaneous and lateral mixing occurs by dispersion.

The lateral solids dispersion coefficients have been evaluated at various operating conditions from the experimental results of tracer concentration versus time. Based on the results, a modification of an existing correlation is proposed.
Hydraulic, mass transfer and heat transfer performance comparison between ordered bed packing and sieve trays
Authors: Spagnolo D. A. , Chuang K. T.
Published: March 2009

The Girdler–Sulfide (GS) heavy water production process has traditionally used tray columns because of their large size. In recent years, the chemical industry has extended the use of packing to larger columns because of economic and performance advantages. A pilot scale study was thus initiated to compare the hydraulic, mass transfer and heat transfer performance of an ordered bed packing (Mellapak) with sieve trays operating under GS process conditions. Mellapak offered lower pressure drops, higher throughputs and improved heat transfer over sieve trays. However, benefits to deuterium mass transfer were only marginal in large diameter columns.
Mass transfer in a single‐hole tray column
Authors: Neuburg H. J. , Chuang K. T.
Published: March 2009

A theoretical model for deuterium exchange in the H2S/H2O system was derived to describe mass transfer in the bubble formation, bubble displacement and bubble breakup regions above a single‐hole tray in an 8 cm diameter transparent column. The model was applied to data measured at 31°C in the pressure range of 790 to 2000 kPa and in a wide range of gas and liquid flows. High speed cinematography was used to measure bubble diameters, bubble formation times and bubble contact times in the liquid, all of which are parameters in the mass transfer models.

Results show that for single‐hole trays and the major part of mass transfer occurs in the upper surface of the froth where bubbles disengage from the liquid. However, when the same model is applied to pilot plant sieve trays, it is shown that the bulk of mass transfer takes place in the region where bubbles are ascending in the froth. The tray efficiencies predicted by the model agree well with measured values.
Electrochemical mass transfer at a fixed bed of spheres under forced convection induced by counterelectrode gas bubbles
Authors: Sedahmed G. H.
Published: March 2009

Rates of mass transfer were measured at a cathode consisting of a fixed single layer of spheres stirred by oxygen evolved at a horizontal disc anode placed below. The rate of mass transfer was found to increase by a factor of 2–6.5 over the natural convection value, depending on the operating conditions.

A mathematical model based on the surface renewal theory was formulated to explain the mechanism of mass transfer at gas stirred electrodes. A new electrochemical reactor built of a series of cells arranged vertically in a cylindrical container, each cell consisting of a screen gas‐evolving counterelectrode placed below a fixed bed working electrode, is proposed as offering an efficient way of stirring with no external stirring power consumption.
The computer‐derivation of thermodynamic equations Part I. First and Second Derivatives for Simple Systems
Authors: Farah N. , Missen R. W.
Published: March 2009

An algorithm is described for the systematic derivation of expressions for first and second thermodynamic derivatives involving the use of Jacobians. The algorithm is implemented by means of a list‐processing language in conjunction with a commercially available symbolic mathematical system for use with a microcomputer. The algorithm is intended to replace tables and procedures currently used “by hand”. Attention is limited in this paper to simple systems with two degrees of freedom, but the algorithm is to be extended ultimately to chemical systems subject to equilibrium constraints. Examples are given to illustrate the procedure.
A new approach to thermal integration of distillation sequences
Authors: Kattan M. K. , Douglas P. L.
Published: March 2009

This paper describes a new approach for synthesizing thermally integrated distillation sequences. There are two key developments in this research. First, the overall flowsheet is optimized simultaneously as opposed to the traditional technique of optimizing each tower sequentially followed by heat integration. Second, maximum energy recovery techniques are used to estimate the total energy requirements of the thermally integrated network, eliminating the need to synthesize a heat exchanger network on each function evaluation in the optimization routine. A frequently reported five component light alkane system (Rathore's Problem) was used to illustrate this approach. Optimized process flowsheets, energy savings and a comparison with literature values are presented.
The effect of geometric parameters on the structure of combined axial and Taylor‐Vortex flow
Authors: Gu Z. H. , Fahidy T. Z.
Published: March 2009

The variation of Taylor‐vortex flow structure with the width of the annulus between concentric cylinders has been studied in combined axial and rotating flow by a direct visualization technique using analytical indicators. The existence of inclined wavy vortex flow with specific transition paths between several wave modes is demonstrated in the low axial Reynolds number range (0 < Re < 50).
Developing and fully developed turbulent flow of drag reducing fluids in an annular duct
Authors: Shenoy A. V. , Shintre S. N.
Published: March 2009

Velocity profiles for the inner and outer flow regions of annuli are proposed for the turbulent flow of drag reducing fluids. Theoretical expressions for friction factors are developed. From the shear stress equations and the velocity profiles, estimates for the entrance lengths are given.
Numerical calculation of particle collection by a row of cylinders in a viscous fluid
Authors: Mclaughlin Carroll , Mccomber Pierre , Gakwaya Augustin
Published: March 2009

A method for calculating the collection efficiency of particles by a row of cylinders in a viscous fluid is presented. The Navier‐Stokes equation is solved by the finite element method to determine the carrier gas velocity field. Then, the particle equation of motion is also solved by the finite element method to find the particle velocity of impact. Finally, the collection efficiency is obtained by integration of the intercepted particles on the cylinder surface. Results of this model are compared with other theoretical models as well as with some experimental data.
Conjugate heat transfer between internal forced and external natural convections with wall conduction
Authors: Mori Shigeru , Gotoh Shinji , Tanimoto Akira , Sakakibara Mikio
Published: March 2009

A new method which combines analytical and numerical solutions is presented for analyzing coupled transport phenomena between multiple regions. The method was applied to simulate heat transfer from hot laminar forced downward convection in a parallel plate duct to external natural convection through a finite section of one wall. Obtained numerical results showed that the longitudinal wall conduction markedly relaxed the thermal interaction between the two convection systems. Experiments were also performed, using conducting walls made of aluminum, stainless steel and granite. Predicted temperature profiles agreed well with the experimental data.
Spouted bed drying of agricultural grains
Authors: Viswanathan K. , Lyall M. S. , Raychaudhuri B. C.
Published: March 2009

It is shown that the presence of a “slotted draft tube” results in reduced air requirements for spouting and improved drying performance. Experimental data are presented on batch as well as continuous spouted bed drying of wheat, paddy, maize and peas. The variables studied are feed moisture content (Qo), inlet air temperature (To), bed mass hold‐up (Mp), inlet superficial air velocity (uo) and bed diameter (Dc) in batch drying, and the above variables and solids feed rate (Fs) in continuous drying. The data on average overall drying rate, ϕm, in kg moisture evaporated per unit time per kg bed solids, is found to be correlatable as ϕm, = k (50Qo + 0.118To − 12.5) 10−5, and the single parameter k is presented for wheat, paddy, maize and peas for both batch and continuous modes of spouted bed drying. The correlation obtained should be useful in dryer design for the grains studied as well as for other similar materials.
Liquid mass transfer in laminar flow in a column containing a string of spheres and cylinders
Authors: Sotelo J. L. , Benitez F. J. , Cabrera L.
Published: March 2009

The absorption of carbon dioxide by aqueous glycerine solutions in a column containing a string of spheres and cylinders has been studied. The Reynolds number was varied between 5 and 560. Using a model based on Higbie's penetration theory, modified to fit the characteristics of this absorber, the number of surface renewals that takes place in the column has been evaluated and correlated with the operating variables that can influence it. The liquid viscosity has no influence on the surface renewal which depends mainly on the liquid rate.
Wetted wall cyclonic tower: An update
Authors: Traverso P. G. , Cecchi F. , Avezzù F. , Badoer S.
Published: March 2009

A pilot—plant investigation of cyclonic wetted‐wall absorption towers has shown that some of the main factors affecting the performance have not yet been correctly accounted for. New empirical correlations for practical designs are presented.
La—Ni system porous anode in an alkaline fuel cell
Authors: Tanaka H. , Kaneki N. , Hara H. , Shimada K. , Takeuchi T.
Published: March 2009

La—Ni system alloys in fine powder form were used to make the hydrogen electrode for an alkaline fuel cell. LaNi5 electrodes were found to have the highest electrode performance among the La—Ni system electrodes. Using LaNi5 powder of mean particle size 3.4 μm for the electrode, the limiting current density was 180 mA/cm2. However mixing the same size powder (mean particle size 3.4 μm) with powder of mean particle size 40.5 μm in a ratio of 4:1, the limiting current density of the new electrode was 250 mA/cm2. The electrode was found to have both relatively fine pores in the range 0.01–0.2 μm and relatively large pores in the ranges 0.5–1 μm and 4–5 μm. Thus, it was found that not only relatively fine pores but relatively large pores had an important effect upon the LaNi5 electrode characteristics.
Hydrocracking of n‐heptane. Study of NiO—MoO3 catalysts supported on a HY ultrastable zeolite
Authors: Vázquez M. I. , Escardino A. , Aucejo A. , Corma A.
Published: March 2009

The hydrocracking of n‐heptane in the temperature range of 573 to 623 K and at 2.45 × 106 Pa pressure has been employed as a test reaction for the study of Ni—Mo bifunctional catalysts supported on a HY ultrastable zeolite.

Two groups of catalysts containing 8 and 12 wt% of MoO3 and different amounts of NiO have been studied. In both series a maximum in the activity has been obtained for catalysts with a Ni/Mo atomic ratio of 0.8‐1.0. The order of the impregnation of the oxides can have little influence on the activity. The most active catalyst has been obtained when the zeolite is exchanged with NH+4 ions until the Na+ level is less than 2% of the original and calcined at 823 K to obtain a HY ultrastable zeolite. Using this catalyst the rate controlling step could be the transformation of the carbonium ion on the acid sites.
Catalytic conversion of canola oil to fuels and chemical feedstocks: Part II Effect of co‐feeding steam on the performance of HZSM‐5 catalyst
Authors: Prasad Y. S. , Bakhshi N. N. , Mathews J. F. , Eager R. L.
Published: March 2009

Ca lola oil and steam were co‐fed continuously to a 15.5 mm i.d. fixed‐bed reactor loaded with HZSM‐5 catalyst at varying process conditions. The liquid hydrocarbon product contained 60–70 wt% aromatics. The gas product was highly olefinic, while for canola oil alone it was mostly paraffinic. The C2‐C5 olefin selectivity increased with an increase in the steam/canola oil ratio in the feed. In addition, co‐feeding with steam resulted in a two‐fold increase in the catalyst life. Though the exact role of steam in altering the chemistry of the reaction is not known, it is probable that the rates of olefin formation and aromatization reactions are affected by the presence of steam. The product pattern suggests the possibility of propene being the initial olefin in the reaction scheme.
Catalytic effect of mineral matter of high ash onakawana lignite on steam gasification
Authors: Furimsky Edward
Published: March 2009

Reactivities of untreated and acid washed Onakawana lignite during steam gasification were compared in a thermo‐balance reactor. The acid treatment resulted in removal of Ca, Mg, Ba and Sr from mineral matter. This was accompanied by a marked decrease in the rates of H2, CO and CO2 formation. The decrease of gasification rate was attributed to the decrease in concentration of gasification sites during the acid treatment.
Erosion and thermal shock tests on ceramic materials
Authors: Whiteway S. G. , Chan E. W. , Kazi A.
Published: March 2009

The resistance to erosion and thermal shock of several ceramic materials, particularly alumina, was measured. The alumina specimens were made by pressing and sintering finely ground particles. The objective was to fabricate wear‐resistant components for a burner assembly used for the atomization and combustion of abrasive coal‐liquid fuels. The test procedures are described, and their use demonstrated to identify a commercially available material from which shapes were prepared to a dimensional accuracy of 0.5%, of 99.5% theoretical density, and having optimized erosion and thermal shock resistance.
PRSV: An improved peng—Robinson equation of state for pure compounds and mixtures
Authors: Stryjek R. , Vera J. H.
Published: March 2009

The temperature and acentric factor dependence of the attractive term of the Peng—Robinson equation of state have been modified. The introduction of a single pure compound parameter allows the accurate reproduction of the vapor pressure data for a wide variety of substances. Nonpolar, polar nonassociating and associating compounds are equally well represented by the cubic PRSV equation of state. The conventional one‐binary‐parameter mixing rule allows the correlation of the vapor—liquid equilibrium data for a wide variety of binary systems. Only for systems formed by a polar compound (associating or not) and a saturated hydrocarbon, are results poorer than those obtained with conventional excess Gibbs energy functions.
PRSV — An improved peng‐Robinson equation of state with new mixing rules for strongly nonideal mixtures
Authors: Stryjek R. , Vera J. H.
Published: March 2009

Two new composition dependent mixing rules for cubic equations of state are proposed. Both mixing rules contain two adjustable binary parameters and reduce to the conventional one parameter mixing rule when the parameters are equal. Vapor‐liquid equilibrium data for mixtures of polar (associated or not) compounds with saturated hydrocarbons and for systems water/alcohol have been used to test the new mixing rules applied to the PRSV cubic equation of state. For these highly nonideal systems, correlation of the data with a new mixing rule of the Van Laar type for the PRSV equation gives better results than those obtained using excess Gibbs energy functions like the Wilson equation, NRTL and UNIQUAC.
Probe for measuring local gas holdups in saline potash pulps
Authors: Zrymiak Tara L. , Hill G. A.
Published: March 2009

A conductivity probe has been designed and used to measure the gas holdup at a point in both two and three phase flows of saline solutions. The probe uses a direct current voltage and acts as a simple on‐off switch. The probe is a single unit with one electrode being the probe body and the other electrode simulating a massless point.

It was found that the probe gave similar gas holdup trends to the pressure drop method of measuring overall gas holdup. When used in a bubble column the probe could be used to indicate bubble sizes and corresponding rise velocities. Equations are presented which were used to convert the electric output of the probe to these physical parameters.
Adsorption of radium‐226 from solution by the container walls
Authors: Tsezos M. , Walker C. , Keller D.
Published: March 2009

This work quantifies the adsorptive uptake of radium‐226 from solution by the walls of the solution container. Three different container materials were examined, each with significantly different critical surface tension. Teflon was shown to be the material with the least radium‐226 adsorption capacity in the examined pH range of 2 to 10. The radium adsorption by Teflon flasks is consistent and predictable. The respective adsorption isotherm is presented. An optimum washing procedure for the Teflon flasks was also defined.
Direct contact heat transfer with phase change: Bubble growth and collapse
Authors: Raina G. K. , Wanchoo R. K.
Published: March 2009

A theoretical expression has been presented for the prediction of the instantaneous heat transfer coefficient of a condensing two‐phase bubble. The modified form of this model predicts very well the available experimental data. Another expression, presented for the total time taken by an evaporating two‐phase drop, also gives very good agreement with the available experimental data.
Wall‐to‐bed heat transfer in liquid—solid and gas—liquid—solid fluidized beds part I: Liquid—solid fluidized beds
Authors: Muroyama K. , Fukuma M. , Yasunishi A.
Published: March 2009

Experimental work was conducted to investigate the effect of particle size and particle density upon the wall‐to‐bed heat transfer characteristics in liquid—solid fluidized beds with a 95.6 mm column diameter over a wide range of operating conditions. The radial temperature profile was found to be parabolic, indicating the presence of a considerable bed resistance. The effective radial thermal conductivity and the apparent wall film coefficient were obtained on the basis of a series thermal resistance model.

The modified Peclet number of the radial thermal conductivity decreases upon the onset of fluidization, has a minimum at a bed porosity of 0.6 to 0.7 and increases with further increase of bed porosity. The modified Peclet number decreases considerably with decreasing particle size or increasing particle density. The apparent wall heat transfer coefficient can be represented well by a Colburn j‐factor correlation over a wide range of data as follows:

j′H = 0.137 Re′−0.271

A close analogy is found to exist between the modified j‐factor for wall heat transfer coefficient and that for wall mass transfer coefficient, in liquid—solid fluidized beds.
Wall‐to‐bed heat transfer in liquid—solid and gas—liquid—solid fluidized beds part II: Gas—liquid—solid fluidized beds
Authors: Muroyama K. , Fukuma M. , Yasunishi A.
Published: March 2009

Wall‐to‐bed heat transfer in gas—liquid—solid fluidized beds with a cocurrent upflow was analyzed on the basis of a series thermal resistance model. The effective radial thermal conductivity and the apparent wall heat transfer coefficient were determined over a wide range of experimental conditions.

The behavior of the effective thermal conductivity strongly depends on the flow mode for the three‐phase fluidized bed, directly indicating the trend of the radial liquid mixing. The modified Peclet number for the radial thermal diffusivity takes on a minimum with respect to the liquid velocity in a manner similar to that in a liquid—solid fluidized bed, but the value of the modified Peclet number decreases significantly with gas velocity. The apparent wall heat transfer coefficient can be correlated well with a Colburn type equation which at zero gas velocity reduces to the same equation as that proposed for liquid—solid fluidization, as follows:

j′H = 0.137 Re′l.g−0.271
Kinetics of isotopic exchange reaction between hydrogen and water vapor over platinum supported on a hydrophobic carrier
Authors: Kawakami Koei , Takao Yuji , Kusunoki Koichiro
Published: March 2009

The isotopic exchange reaction between hydrogen and water vapor was studied for the temperature range 313 K to 353 K over platinum supported on hydrophobic styrene‐divinylbenzene copolymer beads, and, for comparison, platinum supported on hydrophilic alumina pellets. The hydrophobic catalyst exhibited a high activity even with the gas saturated with water vapor, whereas the hydrophilic catalyst showed maximum exchange rate at a relative humidity of approximately 0.6. The dependences of the exchange rates on relative humidity, hydrogen partial pressure and temperature were extensively examined. The combined effect of surface reaction and intraparticle diffusion on the overall exchange reaction was analyzed to explain the kinetic behavior on the hydrophobic catalyst.
Étude de l'hydrogénation sélective du cyclopentadiène sur l'aérogel Cu/Al2O3 fluidisé
Authors: Chaouki J. , Chavarie C. , Klvana D. , Pajonk G.
Published: March 2009

Ce travail évalue l'utilisation de l'aérogel Cu/Al2O3 en lit fluidisé pour l'hydrogénation sélective du cyclopentadiène. Bien qu'appurtenant au groupe C de la classification de Geldart, les particules d'aérogel Cu/Al2O3 réussissent néanmoins à fluidiser via un processus d'agglomération au‐dessus d'une vitesse critique de 0,04 m/s. Une étude cinétique de l'hydrogénation du cyclopentadiène sur cet aérogel a été effectuée dans un réacteur intégral. L'analyse numérique des données cinétiques a permis de dégager une équation de vitesse correspondant au mécanisme de Rideal—Eley où l'étape limitante est la réaction de l'hydrogène gazeux avec le cyclopentadiène adsorbé à la surface du catalyseur. À cause de la faible activité du catalyseur, plusieurs modèles de comportement de réacteur (homogènes ou hétérogènes) peuvent décrire de manière adéquate les conversions obtenues expérimentalement dans un petit réacteur pilote à couche fluidisée. Le modèle piston idéal, plus conforme au comportement pseudo‐homogène du lit, convient cépendant le mieux statistiquement.
Feed composition modulation of hydrocarbon synthesis over a cobalt oxide catalyst
Authors: Adesina A. A. , Hudgins R. R. , Silveston P. L.
Published: March 2009

Studies of the Fischer‐Tropsch reaction over a cobalt catalyst under unsteady‐state conditions (i.e. both step‐change and forced feed composition cycling or feed modulation) have been carried out. Conversions were differential under conditions of atmospheric pressure and 473 K.

The steady‐state rate versus feed composition curves for the alkanes were generally skewed towards the rich‐hydrogen feed compositions, while the olefins exhibited maximum steady‐state rates at the stoichiometric feed reactant ratio. The adsorption of hydrogen in the initiation step or hydrogenation of an unsaturated surface species appeared to be important in determining the alkane formation rates. The appearance of overshoot in the transient responses for some products conforms to the interpretation of a hypothesis of a succession of steady‐state rates on the surface. However, a closer examination of overshoot behaviour suggests that there is participation of carbon from within the catalyst bulk. Significant improvements found for the time‐average rates of some products were consistent with the results of the step‐change experiments.
Hydrogenolysis of n‐Hexadecane on iron and its inhibition by carbon monoxide
Authors: Monnier Jacques , Anderson Robert B. , Quilliam Michael A.
Published: March 2009

The hydrogenolysis of normal hexadecane was studied over iron at 325° and 355°C. As expected with iron catalysts, the main product was methane, but the selectivities for intermediate alkanes were moderately large, probably due to the length of the carbon chain. Furthermore, gas chromatography—mass spectrometry analysis of the heavier products indicated the presence of alkylbenzenes, alkenes and branched alkanes which accounted for about 20 mole % of the C9–C13 hydrocarbons. When 5.7 mole % of carbon monoxide was added to the feed, hydrogenolysis reactions were inhibited and products similar to those in the Fischer—Tropsch synthesis were found. Therefore, CO acts like a poison for the hydrogenolysis of hydrocarbons.
Experimental study on effect of elasticity on drag reduction and turbulent fluctuations in laminar‐turbulent transition region in pipe flow of dilute polymer solutions
Authors: Ogawa Kohei , Kuroda Chiaki
Published: March 2009

By utilizing the fact that physical properties exclusive of elasticity of dilute polyacrylamide solutions do not change with elapsed time after preparation, the effect of elasticity on drag reduction and turbulent fluctuations in pipe flow was investigated experimentally.

The oscillations of axial velocity and velocity gradient and the drag reduction in the laminar‐turbulent transition region are affected significantly by the value of elasticity. The laminar‐turbulent transition region moves to a higher Reynolds number as the value of elasticity increases.
A note on the upper bound of the temperature solution of the axial dispersion model for a tubular reactor
Authors: Viljoen H. J.
Published: March 2009

The existing a‐priori bound of the temperature solution of the axial dispersion one‐dimensional model of the tubular reactor does not take parameters like Damköhler number into consideration. Utilizing the properties of the nonlinear term in the model equations enables one to find improved upper bounds which depend on all the model parameters. Only for the case of Lewis number greater than unity and Damköhler number sufficiently large, is the existing bound not improved.
Evaporation of volatile liquids from an open‐topped, partially filled container to an air stream
Authors: Prata A. T. , Sparrow E. M.
Published: March 2009

Experiments were performed to measure the evaporative mass transfer from a partially filled, slot‐like container recessed in the floor of a flat rectangular duct through which turbulent air flow was passed. Toluene and cumene were used as the evaporating liquids, and systematic variations were made of the Reynolds number and of the distance between the top of the container and the surface of the evaporating liquid. The measured Sherwood numbers displayed unconventional dependences on both the Reynolds and Schmidt numbers as well as a complex dependence on the top‐to‐surface distance.
Mn and Zn doped ZSM‐5 zeolite catalysts
Authors: Mao Raymond Le Van , LÉVesque Pierre , Sjiariel Bernard
Published: March 2009

Manganese was incorporated into a ZSM‐5 zeolite by a special impregnation method which practically prevented the deposition of the metal ions on the internal surface of the zeolite pores. As a result, the production of light olefins increased sharply while that of aromatics did not significantly change. The double incorporation of Zn (by ion‐exchange) and of Mn (by this impregnation technique) led to catalysts which could produce more aromatics and more light olefins (mainly ethylene and propylene) than the parent ZSM‐5 zeolite.
Polyelectrolyte behaviour of ligninsulphonates
Authors: Bui V. T. , Hachey J. M. , Tremblay Y.
Published: March 2009

Two commercial ligninsulphonate samples have been investigated by means of gel permeation chromatography (GPC), viscosity, potentiometric titration and conductivity measurements. The molecular‐weight distributions given by GPC showed that the two samples consisted of a large portion of high molecular weight materials (¯w > 50 000), and a small part of low molecular weight (¯w ≃ 5000). The results obtained from titration yielded a sodium content of about 6% for both samples, and these results also confirmed that the samples do not contain any simple salts like NaHSO3 as impurity. The viscosity and conductivity data for moderate and very dilute solutions clearly demonstrated the polyelectrolyte behaviour of ligninsulphonates molecules. The equivalent conductivity at infinite dilution, Λ0, were there‐from deduced for the two samples used.
On power input and liquid‐phase mixing times in pneumatically‐agitated contactors: Response to critique of guy et al.
Authors: Robinson Campbell W.
Published: March 2009

The total power input to a pneumatically‐agitated gas—liquid contactor in principle is the sum of the contributions of isothermal gas expansion (p‐V work) and the changes in the potential and kinetic (ΔKE) energies of the flowing gas. The latter energy change is dependent, in part, on the pressure drop in the sparger orifices. Guy et al. (1986a) strongly infer that in practice ΔKE is never negligible compared to the p‐V work and claim that Bello et al. (1984) made a serious error in neglecting the ΔKE contribution in their cases, which error may have made their relative mixing time comparisons invalid.

This communication shows that for the work of Bello et al. (1984), the ΔKE contribution was in fact negligibly small, whereas for the spargers used by Guy et al. (1986b) it was not. Furthermore, it is shown that the implication of Guy et al. (1986a) that bubble columns (BC) produce better or equivalent liquid‐phase mixing than do stirred tanks (ST) is not universally true. The relative performance of BC and ST contactors is highly dependent upon the dispersion height: diameter ratio of the former, which ratio was quite different in the works of Bello et al. (1984) and Guy et al. (1986b).
Industrial mammalian cell culture
Authors: Adamson S. R. , Schmidli B.
Published: March 2009

A number of proteins with potential therapeutic uses (monoclonal antibodies, interferons, plasminogen activators) have been produced in mammalian cells. Novel bioreactor designs used to generate high density cultures mostly employ methods which approximate in vivo homeostasis. These perfusion and dialysis culture systems maintain the concentration of medium components and growth factors at a relatively high level while minimizing the accumulation of growth inhibitory metabolites. These methods include microcarrier culture, microencapsulation and other forms of entrapment, perfusion suspension culture in continuous stirred tank reactors, hollow fibres and combinations thereof. A summary of the status of industrial mammalian cell culture will be presented with examples illustrating the processes above.
Hydrodynamics and urea hydrolysis in a microencapsulated urease, fluidized bed reactor
Authors: Dueck C. L. , Neufeld R. J. , Chang T. M. S.
Published: March 2009

Urease was encapsulated in ultra‐thin, semi‐permeable cellulose nitrate membranes by simple interfacial precipitation. A fluidized bed reactor was designed and constructed for containing the shear sensitive urease microcapsules. The feasibility of maintaining high conversions of urea by providing an adequate mixing regime, while eliminating the damaging effects of shear was demonstrated. A reactor productivity of 0.7 mmoles urea/sL was observed at a superficial velocity of 3.3 × 10−4 m/s using a simulated blood plasma solution. This represents a 44% conversion of urea.
Asborin: The Carbaborane Analogue of Aspirin
Authors: Scholz Matthias , Bensdorf Kerstin , Gust Ronald , Hey‐Hawkins Evamarie
Published: March 2009

Asborin, the carbaborane analogue of aspirin, was obtained by a high‐yield synthetic procedure and proved to be an active cyclooxygenase (COX) inhibitor (H: white, B: beige, C: gray, O: blue).

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18F‐fluorodeoxyglucose and 11C‐acetate positron emission tomography are useful modalities for diagnosing the histologic type of thymoma
Authors: Shibata Hidekatsu , Nomori Hiroaki , Uno Kimiichi , Sakaguchi Kazuya , Nakashima Rumi , Iyama Kenichi , Tomiyoshi Katsumi , Kaji Masahiro , Goya Tomoyuki , Suzuki Takashi , Horio Hirotoshi
Published: March 2009

BACKGROUND:

The objective of this study was to clarify the usefulness of positron emission tomography (PET) using18F‐fluorodeoxyglucose (FDG) and carbon 11‐labeled acetate (AC) for predicting the histologic types and tumor invasiveness of thymoma in a multicenter study.

METHODS:

Forty thymomas were examined using both FDG‐PET and AC‐PET before surgery. The histologic types were type A in 1 thymoma, type AB in 12 thymomas, type B1 in 11 thymomas, type B2 in 7 thymomas, type B3 in 6 thymomas, and type C in 3 thymomas. Tumor invasiveness was assessed by pathologic tumor stage and was identified as stage I in 17 tumors, stage II in 17 tumors, stage III in 4 tumors, and stage IV in 2 tumors. FDG and AC uptake was measured as the maximum standard uptake value (SUV).

RESULTS:

The FDG‐SUV in type C thymomas was significantly higher than that in the other types (A‐B3; P = .001 – P = .048). The AC‐SUV in type A/AB thymomas was significantly higher than that in the other tumor types (B1‐C; P < .001 – P = .002). All 3 type C tumors had an FDG‐SUV ≥6.3, and all 13 type A/AB tumors had an FDG‐SUV <6.3 and an AC‐SUV ≥5.7. All 17 thymomas that had an FDG‐SUV <6.3 and an AC‐SUV <5.7 were type B1, B2, or B3. Neither the FDG‐SUV nor the AC‐SUV differed significantly between the stages I/II tumors and stage III/IV tumors.

CONCLUSIONS:

Although neither the FDG‐SUV nor the AC‐SUV can predict the invasiveness of thymomas assessed by tumor stage, they are useful for predicting histologic types of thymoma. Thymomas with an FDG‐SUV <6.3 and an AC‐SUV ≥5.7 almost certainly are types A/AB, which is of considerable prognostic and management significance. Cancer 2009. © 2009 American Cancer Society.
Chloroquine in glioblastoma—New horizons for an old drug
Authors: Munshi Anusheel
Published: March 2009

Interesting clinical data have emerged about clinical experience with chloroquine as adjuvant therapy for patients with glioblastoma multiforme (GBM). Chloroquine has the potential of opening new frontiers in the treatment of glial neoplasms and should be tested in large clinical trials.
Real‐time identification of liver cancers by using indocyanine green fluorescent imaging
Authors: Ishizawa Takeaki , Fukushima Noriyoshi , Shibahara Junji , Masuda Koichi , Tamura Sumihito , Aoki Taku , Hasegawa Kiyoshi , Beck Yoshifumi , Fukayama Masashi , Kokudo Norihiro
Published: March 2009

BACKGROUND:

We have often encountered difficulties in identifying small liver cancers during surgery. Fluorescent imaging using indocyanine green (ICG) has the potential to detect liver cancers through the visualization of the disordered biliary excretion of ICG in cancer tissues and noncancerous liver tissues compressed by the tumor.

METHODS:

ICG had been intravenously injected for a routine liver function test in 37 patients with hepatocellular carcinoma (HCC) and 12 patients with metastasis of colorectal carcinoma (CRC) before liver resection. Surgical specimens were investigated using a near‐infrared light camera system. Among the 49 subjects, the 26 patients examined during the latter period of the study (20 with HCC and 6 with metastasis) underwent ICG‐fluorescent imaging of the liver surfaces before resection.

RESULTS:

ICG‐fluorescent imaging identified all of the microscopically confirmed HCCs (n = 63) and CRC metastases (n = 28) in surgical specimens. Among the 63 HCCs, 8 tumors (13%, including 5 early HCCs) were not evident grossly unless observed by ICG‐fluorescent imaging. Five false‐positive nodules (4 large regenerative nodules and 1 bile duct proliferation) were identified among the fluorescent lesions. Well‐differentiated HCCs appeared as uniformly fluorescing lesions with higher lesion‐to‐liver contrast than that of moderately or poorly differentiated HCCs (162.6 [71.1‐218.2] per pixel vs 67.7 [‐6.3‐211.2] per pixel, P < .001), while CRC metastases were delineated as rim‐fluorescing lesions. Fluorescent microscopy confirmed that fluorescence originated in the cytoplasm and pseudoglands of HCC cells and in the noncancerous liver parenchyma surrounding metastases. ICG‐fluorescent imaging before resection identified 21 of the 41 HCCs (51%) and all of the 16 metastases that were examined.

CONCLUSIONS:

ICG‐fluorescent imaging enables the highly sensitive identification of small and grossly unidentifiable liver cancers in real time, enhancing the accuracy of liver resection and operative staging. Cancer 2009. © 2009 American Cancer Society.
Distinct roles of neuropilin 1 signaling for radial and tangential extension of callosal axons
Authors: Hatanaka Yumiko , Matsumoto Tomoko , Yanagawa Yuchio , Fujisawa Hajime , Murakami Fujio , Masu Masayuki
Published: March 2009

Cortical excitatory neurons migrate from their origin in the ventricular zone (VZ) toward the pial surface. During migration, these neurons exhibit a stellate shape in the intermediate zone (IZ), transform into bipolar cells, and then initiate radial migration, extending a trailing process, which may lead to an axon. Here we examined the role of neuropilin 1 (NRP1) in these developmental events. Both NRP1 mRNA and protein were highly expressed in the IZ, where stellate‐shaped cells were located. DiI labeling experiments showed that neuronal migration occurred normally in Nrp1 mutant mice up to embryonic day (E) 14.5, the latest day to which the mutant survives, with only subtle axonal defasciculation. However, interference with Nrp1 signaling at a later stage caused pathfinding errors: when a dominant negative form of Nrp1 was electroporated into the cortical VZ cells at E12.5 or E15.5 and examined perinatally, guidance errors were found in tangential axonal extension toward the midline. In contrast, no significant effect was noted on the migration of cortical excitatory neurons. These findings indicate that NRP1 plays an important role in the guidance of callosal axons originating from cortical excitatory neurons but does not support a role in their migration. Moreover, insofar as radial axonal extension within the cortical plate was unaffected, the present findings imply that molecular mechanisms for the axonal extension of excitatory neurons within the cortical plate are distinct from those in the white matter. J. Comp. Neurol. 514:215–225, 2009. © 2009 Wiley‐Liss, Inc.
A solver combining reduced basis and convergence acceleration with applications to non‐linear elasticity
Authors: Cadou J. M. , Potier‐Ferry M.
Published: March 2009

An iterative solver is proposed to solve the family of linear equations arising from the numerical computation of non‐linear problems. This solver relies on two quantities coming from previous steps of the computations: the preconditioning matrix is a matrix that has been factorized at an earlier step and previously computed vectors yield a reduced basis. The principle is to define an increment in two sub‐steps. In the first sub‐step, only the projection of the unknown on a reduced subspace is incremented and the projection of the equation on the reduced subspace is satisfied exactly. In the second sub‐step, the full equation is solved approximately with the help of the preconditioner. Last, the convergence of the sequences is accelerated by a well‐known method, the modified minimal polynomial extrapolation. This algorithm assessed by classical benchmarks coming from shell buckling analysis. Finally, its insertion in path following techniques is discussed. This leads to non‐linear solvers with few matrix factorizations and few iterations. Copyright © 2009 John Wiley & Sons, Ltd.
Metal‐Insulator Transition‐Induced Adsorption‐Resistant Behavior of Small Au Nanoparticles
Authors: Kim Hyo‐Sang , Shin Sun‐Young , Uhm Sanghoon , Han Jin‐Hee , Hwang Han‐Na , Kim Bongsoo , Chung Jinwook , Kim Young D. , Hwang Chan‐Cuk
Published: March 2009

Smaller nonmetallic nanoparticles are more inert: Metal–insulator transition of Au nanoparticles on silica is closely related to the metal–support charge transfer, which has a strong influence on chemisorption reactivity of Au. Smaller nonmetallic Au nanoparticles are more resistant towards butanethiol chemisorption (see picture and graph).

magnified image

The size‐dependent variation of the electronic and chemical properties of Au nanoparticles formed on native Si oxide surfaces is investigated using synchrotron radiation photoemission spectroscopy and ultraviolet photoelectron spectroscopy. The adsorption reactivity toward butanethiol adsorption initially increases with decreasing particle size; however, the reactivity of Au nanoparticles becomes gradually lower below a size of ∼0.8 nm. The photoemission spectral changes suggest a metal–insulator transition, accompanied by negative charge transfer from the nanoparticles to the support, which may be the source of the chemical inertness of small Au nanoparticles.
A new approach for exploring functional development of fetal brain pathways
Authors: Shi Lijun , Liu Yujuan , Mao Caiping , Zeng Fanxing , Meyer Kurt , Xu Zhice
Published: March 2009

Study of functional development of central pathways in fetuses is challenging due to the lack of methods available. In this article, we present a novel approach to test if and when central functional pathways are established by a combination of mapping with c‐fos and chronically cannulated fetuses in utero. This approach is based on brain structures such as circumventricular organs (CVOs) that lack the blood–brain barrier (BBB), but are rich in sensors to peripheral signals and contain projections to other brain regions. If signaling molecules in the blood that are too large to cross the BBB induced c‐fos expression in both the CVOs and other nuclei inside the fetal brain, this can be evidence that projections from the CVOs to those nuclei are established and functional. This is a useful real‐time method to explore the status of functional maturation of pathways between the CVOs and other brain areas in developing fetuses. Notably, at the moment, this is the first and only in vivo method that can detect functional projections in the fetal brain in vitro. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 384–388, 2009.
Phenotypic analysis of deflated/Ints7 function in Drosophila development
Authors: Rutkowski Rachael J. , Warren William D.
Published: March 2009

The Drosophila gene deflated (CG18176; renamed after the pupal lethal abdominal phenotype of mutant individuals) is a member of a conserved gene family found in all multicellular organisms. The human orthologue of deflated (Ints7) encodes a subunit of the Integrator complex that associates with RNA polymerase II and has been implicated in snRNA processing. Since loss‐of‐function analyses of deflated have not yet been reported, we undertook to investigate deflated expression patterns and mutant phenotypes. deflated mRNA was detected at low levels in proliferating cells in postblastoderm embryos and GFP tagged protein is predominately nuclear. Generation and analysis of four mutant alleles revealed deflated is essential for normal development, as mutant individuals displayed pleiotropic defects affecting many stages of development, consistent with perturbation of cell signalling or cell proliferation. Our data demonstrate multiple roles in development for an Ints7 homologue and to demonstrate its requirement for normal cell signalling and proliferation. Developmental Dynamics 238:1131–1139, 2009. © 2009 Wiley‐Liss, Inc.
Commentaries on ‘Fluid therapy for acute bacterial meningitis’
Authors: Singal Mona , Skippen Peter , Isaacs David
Published: March 2009

These are commentaries on a Cochrane review, published in this issue of EBCH, first published as: Maconochie IK, Baumer JH, Stewart M. Fluid therapy for acute bacterial meningitis. Cochrane Database of Systematic Reviews 2008, Issue 1. Art. No.: CD004786. DOI: 10.1002/14 651 858.CD004786.pub3.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying Summary article. Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration
Commentary on ‘Over‐the counter medications for acute cough in children and adults in ambulatory settings’
Authors: Smith Michael B. H.
Published: March 2009

This is a commentary on a Cochrane review, published in this issue of EBCH, first published as: Smith SM, Schroeder K, Fahey T. Over‐the‐counter medications for acute cough in children and adults in ambulatory settings (Review). Cochrane Database of Systematic Reviews 2008, Issue No. 1. Art No.: CD001831. DOI:10.1.002/14 651 858.CD001831.pub3.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying Summary article. Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration
Centrosome overduplication, chromosomal instability, and human papillomavirus oncoproteins
Authors: Duensing Anette , Spardy Nicole , Chatterjee Payel , Zheng Leon , Parry Joshua , Cuevas Rolando , Korzeniewski Nina , Duensing Stefan
Published: March 2009

Centrosome aberrations are a frequent finding in human tumors. However, very little is known about the molecular mechanisms leading to disruption of centrosome duplication control and the functional consequences of aberrant centrosome numbers. The high‐risk human papillomavirus Type 16 (HPV‐16) E6 and E7 oncoproteins are overexpressed in HPV‐associated malignancies of the anogenital tract and have been instrumental in delineating different pathways of centrosome amplification. Whereas the E6 oncoprotein was found to provoke centrosome accumulation, the HPV‐16 E7 oncoprotein triggers a genuine disruption of the centrosome duplication cycle. Importantly, the E7 oncoprotein can rapidly cause centrosome overduplication through a pathway that involves the concurrent formation of multiple daughters at single maternal centrioles (centriole flowers). Several lines of evidence suggest that cyclin E/CDK2 complexes and Polo‐like kinase 4 (PLK4) are crucial players in this process. These findings underscore that the HPV‐16 E7 oncoprotein is a unique tool to dissect normal and abnormal centriole biogenesis and the underlying molecular circuitry. Environ. Mol. Mutagen. 2009. © 2009 Wiley‐Liss, Inc.
Viral transformation and aneuploidy
Authors: Yasunaga Junichiro , Jeang Kuan‐Teh
Published: March 2009

Human tumor viruses are associated with a variety of human malignancies, and it is estimated that 15% of all human cancers have a viral etiology. An abnormality in chromosomal ploidy or aneuploidy is a hallmark of cancers. In normal cells, euploidy is governed by several factors including an intact spindle assembly checkpoint, accurate centrosome duplication, and proper cytokinesis. Viral oncoproteins are suggested to perturb the cellular machineries for chromosomal segregation creating aneuploidy which can lead to the malignant transformation of infected cells. Here, we review in brief some of the mechanisms used by viruses that can cause cellular aneuploidy. Environ. Mol. Mutagen. 2009. © 2009 Wiley‐Liss, Inc.