bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrodynamics of shallow, conical spouted beds
Authors: Choi Michael , Meisen Axel
Published: March 2009

Experiments were conducted with shallow beds, in the presence of atomizing air injected into the base, under the following conditions: Particles — urea, sulphur coated urea, polyethylene, polyformaldehyde and polystyrene; particle diameters (dp) – 2.1 to 2.8 mm; cone angle – 60°; cylindrical bed diameter (D) – 0.24 and 0.45 m; bed height (H) – 0.24 to 0.40 m; orifice diameter (di) – 21 to 35 mm; main spouting air (Qs) ≤ 37 L(actual)/s; atomizing air (Qa) ≤ 0.87 L(actual)/s. The minimum spouting velocity is well represented by:

Ums = 13.5 (2gH)0.5 (dp/D')1.17 (D'i/D')0.372 (H/D')−0.148 [(τp ‐ τ)/τ]0.289

where D' and D'i denote the modified column and orifice diameter, respectively. Qa, which affects D'i, significantly influenced the air velocity in the spout, but not the pressure profiles in the annulus. Morgan and Littman's (1980) correlation could be adapted to predict the experimental pressure profiles in the annulus.
Catalytic cracking of tar in biomass pyrolysis gas in the presence of calcined dolomite
Authors: Vassilatos V. , Taralas G. , Sjöström K. , Björnbom E.
Published: March 2009

The possibility of decreasing the content of tar in the fuel gas obtained by biomass pyrolysis has been studied. Catalytic cracking of the tar in presence of dolomite was used. Dolomite showed a high catalytic activity. The overall effect of the dolomite is to increase the gas yield by decreasing the tar yield. The dolomite and the steam used seem to affect the amount of naphthalene produced. By adjusting both the amounts of catalyst and steam, we were able to decrease significantly naphthalene (13 mg/kg dry substance biomass) and amount of tar (164 mg/kg dry substance biomass).
Friction factors and bubble dynamics in polymer solutions
Authors: De Kee D. , Carreau P. J.
Published: March 2009

This work reports on bubble dynamics in polymer solutions of various rheological character. Relations between the friction factor and the Reynolds number are discussed and master curves based on the results of Kawase and Moo‐Young are presented and analyzed using two different viscosity expressions. The theoretical results overpredict the friction coefficient except at very high deformation rates. The surface tension is shown to affect the shape of the bubbles but not their velocity, except for bubble volumes smaller than 10‐7 m3.
Lectrochemical oxidation of oxalate in alkaline solutions
Authors: Marsen J. , Hinatsu J.T. , Smith J.W. , Foulkes F.R.
Published: March 2009

Experimental results show that the electrochemical oxidation of oxalate in alkaline solutions at lead dioxide anodes can be achieved at conditions of much higher alkalinity than previously reported in the literature using other types of electrodes. The oxalate in solutions containing 0.05 mol/L ∽0.1 mol/L sodium oxalate was anodically oxidized to carbonate with high efficiency in the presence of up to ∽0.1 mol/L NaOH at 70°C by using lead dioxide anodes doped with silver and tin. The addition of small amounts of silver and tin (e.g., 0.06% by weight) to lead dioxide films significantly increases the oxalate oxidation currents and current efficiencies. These metals can be incorporated into the lead dioxide films by in situ oxidation of lead‐silver‐tin alloys. Although oxalate could not be electrochemically oxidized using lead dioxide electrodes at extremely high pH's (greater than ∽ 14), reduction of the oxalate concentration to less than about 0.04 mol/L could be achieved at greater than 50% current efficiency at pH's up to about 13.
The solubility of carbon dioxide and hydrogen sulfide in a 35 wt% aqueous solution of methyldiethanolamine
Authors: Jou Fang‐Yuan , Carroll John J. , Mather Alan E. , Otto Frederick D.
Published: March 2009

The solubility of hydrogen sulfide and carbon dioxide in an aqueous solution containing 35 wt% methyldiethanolamine (MDEA) (3.04 kmol/m3, 4.52 mol/kg) has been measured at 40° and 100°C at partial pressures of the acid gas up to 530 kPa. Some data for hydrogen sulfide in a 50 wt% solution of MDEA (4.38 kmol/m3, 8.39 mol/kg) were also obtained. Also, densities of CO2‐aqueous MDEA solutions were measured at 40°C.
A group‐contribution correlation for predicting the acentric factors of organic compounds
Authors: Han Buxing , Peng Ding‐Yu
Published: March 2009

A group‐contribution correlation has been developed for the estimation of the acentric factors of organic compounds. The novelty of the proposed method is that it involves the use of only the structural information of the compounds. For the 219 substances considered in this study, the calculated results deviate from the literature values by an average error of 4.2%.
Iterative parameter estimation for extraction of crystallization kinetics of potassium chloride from batch experiments
Authors: Dash S. R. , Rohani S.
Published: March 2009

Extraction of crystallization kinetics, the fundamental information which governs the performance of a crystallization process, is characterized by experimental difficulties in MSMPR and mathematical difficulties in batch crystallization. Here, a rigorous approach is taken to estimate kinetic parameters from a batch crystallizer. The two step LaxWendorff technique is adapted for the solution of the population balance in a batch crystallizer and an iterative self‐correcting least squares algorithm is implemented for the estimation of the kinetic parameters. The need for multi‐response estimation as opposed to single‐response from terminal CSD is demonstrated. The kinetics extracted are average ones, representing primary and secondary nucleation kinetics. It is found that the kinetic parameters estimated by multi‐response technique have a superior predictive capability as opposed to those obtained using the terminal CSD only. An advantage of the proposed algorithm is that the measurement of course of supersaturation, which is difficult to perform, is not required.
Entrance laminar flows of viscoplastic fluids in concentric annuli
Authors: Round G. F. , Yu S.
Published: March 2009

Developing flows of generalized Bingham (Herschel‐Bulkley) fluids in concentric annuli were studied numerically. A control volume approach based upon an upwinding finite difference technique was used to solve the equation of motion. The results in terms of velocity and pressure drop profiles are shown graphically. Radius ratios of 0.02, 0.2, 0.4 and 0.6; power‐law indices (n) of 0.7, 1.0 and 1.2; generalized Bingham numbers of 5, 10 and 15 were investigated. At present, there are no experimental results with which to make comparisons. However, there are results for fully developed flows and comparison has been made with these. In all cases the agreement was good.
Pyrolysis of canmet coprocessing residue in argon/hydrogen plasma
Authors: El‐Naas M. H. , Munzm R. J. , Berk D.
Published: March 2009

The continuous pyrolysis of CANMET coprocessing residue in argon/hydrogen plasma was studied for the temperature range 2700 to 3670 K using an induction plasma torch. Hydrogen was injected into the argon plasma tailflame at molar concentrations ranging from 0 to 23 %. The residue was continuously fed in liquid form to a laboratory‐scale reactor specially built for the study. The residue flow rate ranged from 6 to 9 g/min. A maximum of 10% of the residue pyrolysed with up to 90 % conversion to gaseous hydrocarbons. The rate of residue pyrolysis and the rate of formation of the gaseous products were found to be strongly dependent on the rate of heat transfer at the residue surface. The only gaseous products detected were acetylene, ethylene and methane. Some soot was produced, but no liquid hydrocarbons were detected.
The effect of oxygen upon the kinetics of glucose oxidase inactivation
Authors: Venugopal Ramakrishnan , Saviue Bradley A.
Published: March 2009

The effect of oxygen upon the inactivation rate of glucose oxidase was studied. Tests on enzyme stability during catalytic turnover were conducted under a range of oxygen partial pressures. A standard activity assay was used to monitor changes in glucose oxidase activity.

Studies revealed that oxygen influenced the inactivation of glucose oxidase. Inactivation rates during catalytic turnover ranged between 0.01143 +/‐ 0.0016 h‐1 under 10 kPa oxygen to 0.04879 +/‐ 0.0023 h‐1under 101 kPa oxygen. Statistically different inactivation rates were obtained at oxygen partial pressures of 10,15, 21, 51, and 76 kPa. The enzymatic turnover number decreased from 11.0 X 104 to 5.7 X 104when the oxygen partial pressure increased from 10 to 101 kPa, suggesting that enzyme utilization was most efficient at low oxygen partial pressures (<15 kPa).
A simple correlation for estimating viscosities of solutions of salts in aqueous, non‐aqueous and mixed solvents applicable to high concentration, temperature and pressure
Authors: Kumar Anil
Published: March 2009

A new correlation is proposed to correlate the viscosities of salt solutions in aqueous, non‐aqueous solvents and their mixtures. The correlation involves two parameters i.e. solvation number and ion‐solvent interaction coefficient, which are well‐documented quantities in the literature. The proposed correlation has been examined on the experimental viscosity data of salt solutions in aqueous, non‐aqueous and their mixtures up to 473 K and 31 MPa pressure. The salts with various ionic charges were employed for testing the proposed correlation. Several non‐aqueous solvents like dimethyl sulphoxide, alcohols and formamide were included for the data regression. The viscosities of these solutions can be correlated to within 0.7%.
Size distribution of drops formed from nozzles in liquid‐liquid systems at velocities below jetting
Authors: Karagiannis Constantinos , Papageorgiou Dimitrios , Stamatoudis Michael
Published: March 2009

The size distribution of drops formed from four different diameter nozzles (d=l.O, 1.6, 2.6 and 3.5 mm) was measured over the flow rate range of 0.17 to 3.0 cm3/s (below jetting). Kerosene was used as the dispersed phase and distilled water was used as the continuous phase. The experimental drop size distributions were described adequately by the upper limit number and volume distributions. Plots of the maximum and the minimum diameters versus the mean diameter yielded straight line with slopes of 1.11 and 0.87, respectively.
Analysis of the stratified / nonstratified transitional boundary in horizontal and slightly inclined condensing flows
Authors: Nitheanandan T. , Soliman H M.
Published: March 2009

A mechanistic model has been developed for determining the stratified boundary for condensing flows in horizontal and slightly inclined tubes. Two formulations, a complete and a simplified version are considered for the equilibrium liquid level. Good agreement is found between the two formulations and generalized results were derived from the simplified version of the model. From these results, the effect of condensation is shown to be equivalent to adding a small upward inclination in adiabatic gas‐liquid flow. The predicted transition line is compared with flow‐regime data of different fluid properties, tube diameters, and inclinations. The predictions agreed reasonably well with the data.
Relative Supersaturation Ratio and Separation Factor in Crystallization with High Pressure C02
Authors: Chang Chiehming J. , Liou Yuchung , Lan Wen‐Jen
Published: March 2009

Crystallization in the presence of high pressure gas as antisolvent could be applied for the recovery of valuable compounds from liquid solution. A study of separation behavior is presented here for a mixture of anthracene (AN) and anthraquinone (AQ) in cyclohexanone (CX) expanded with a gaseous antisolvent, CO2. The pressure range was 0.1 to 12 MPa; the temperature was either 292 or 313K. Separation factors were obtained from the measured salted‐out yields and the supersaturation of each solute could be also obtained for this pressure‐tuning crystallization. The separation factor varies almost linearly with relative supersaturation ratio in the crystallization of anthracene‐anthraquinone from cyclohexanone and CO2.
Surface conditioning for potash electrostatic separation
Authors: Zhou G. , Moon K.
Published: March 2009

A simple apparatus for measuring contact charge was set up and utilized to identify and evaluate some effective chemicals for increasing contact charge between potash components. TiCl4 and FeCl2 · 4H20 increase contact potential by unevently raising the surface work functions of NaCl and KCl, while octanoic acid increases this potential by lowering the NaCl surface work function and slightly raising the KCl surface work function. Combinations of these two types of chemicals produce excellent results. Repetition of contacts affects the contact charge. The relationship between the amount of contact and potash contact charge was investigated, as was the effect of hematite contamination of sylvite contact charge.
Kinetics and mechanism of the vapour phase nitroxidation of toluene over nickel oxide‐aluminium oxide catalyst
Authors: Prasad R. , Garg A. , Mathews S.
Published: March 2009

The kinetics of the oxidation of toluene by nitric oxide over nickel oxide‐aluminium oxide catalyst has been studied in the temperature range 280‐380°C. A rate equation Rn= ktptknPn I (k1P1 + knPn) was deduced, assuming a steady state involving a two‐stage irreversible oxidation‐reduction process. The model represented the data satisfactorily for the conversion of toluene to benzonitrile.
Kinetics of hydrogen reduction of sodium sulfate mixed with sodium titanate
Authors: Zou X. , Avedesian M. M. , van Heiningen A. R. P.
Published: March 2009

The hydrogen reduction kinetics of solid sodium sulfate mixed with sodium titanate are studied in a thermogravimetric system. The conversion‐time curves of the hydrogen reduction are sigmoidal in shape and are well described by the nucleation and growth model up to about 60% conversion. The reduction rate of this mixture is much faster than that of pure sodium sulfate. In the deceleratory conversion period, the reduction is controlled by gas diffusion through a product layer. Activation energies of 302 and 179 kJ/mol are obtained, respectively, for the nucleation and growth, and diffusion limited period. The influence of hydrogen concentration, steam concentration, sodium sulfate fraction, and sodium sulfide addition is also studied. A reaction mechanism is proposed for the hydrogen reduction in the solid state.
Particle suspension hydrodynamics in a tapered gas agitated reactor
Authors: Kleijntjens R. H. , van der Lans R. G. J. M. , Luyben K. Ch. A. M.
Published: March 2009

Experiments were carried out in a tapered gas agitated solid‐liquid‐gas (S‐L‐G) reactor at 4 reactor volumes (up to 4 m3 ) with 4 different slurry densities (up to 40 mass%). Using monodisperse sand particles (260 μm diameter) at a low specific power input (ranging from 50‐300 W/m3), minimal suspension was achieved. The spatial solids hold‐up distributions were determined using a specially designed sampling probe. In combination with a mathematical model, the measurements show that a decrease in the ratio of the eddy length and the particle diameter (le/dP) takes place at increasing slurry densities. At a solids hold‐up of about 0.4, the critical lower limit (l < le/dp < 5). below which no suspension state can exist, is reached.
Neural network based objective flow regime identification in air‐water two phase flow
Authors: Cai Shiqian , Toral Haluk , Qiu Jianhung , Archer John S.
Published: March 2009

The Kohonen self‐organising neural network was applied to identify flow regimes in horizontal air‐water flow. The neural network was trained with stochastic features derived from turbulent absolute pressure signals obtained across a range of flow regimes. The feature map succeeded in classifying samples into distinctive flow regime classes consistent with the visual flow regime observation.
Amelioration du transfert convectif de chaleur par l'écoulement pulse dans un fluide visqueux
Authors: Shuai X. , Cheng S. , Antonini G.
Published: March 2009

Les effets de perturbations pulsatoires sur le transfert convectif de chaleur dans un fluide visqueux coulé en régime laminaire ont été étudiés dans un éhangeur de chaleur à tubes cylindriques coaxiaux, la plage de température expérimentale étant de 30°C a 45°C. Le fluide étudié dont la viscosité est douze fois supérieure à celle de l'eau à la tempé5rature ambiante est une solution aqueuse de glycérol à 60% par poids, le nombre de Reynolds des écoulements permanents varie de 150 à 1000. La présence des pulsations augmente de façon significative le transfert thermique, et ce à puissance mécanique dissipée identique. Nous avons en effet obtenu des améliorations du coefficient de transfert de plus de 300% grâe h fortes perturbations pulsatoires. Ainsi, des pulsations imposées à l'écoulement permanent représentent un moyen simple et efficace pour améliorer les échanges thermiques dans des fluides visqueux habituellement pompés en régime laminaire. Une corrélation établie à partir de nos données expérimentales en écoulement pulsé permet d'évaluer le nombre de Nusselt avec une erreur moyenne de 10%.
Thermal plasma production of fumed silica: The effect of quench conditions on thickening and thixotropic ability
Authors: Addona T. , Munz R. J.
Published: March 2009

The effect of quench conditions on the thickening and thixotropic ability of fumed silica was studied. The powder was generated by rapidly quenching a vapour stream containing SiO(g) with steam. Silicon monoxide vapour was produced by decomposing quartz in a transferred arc reactor using an Ar/NH,3 thermal plasma. The parameters investigated included pre‐quench temperature (1100‐2100 K), and supersaturation ratio (1 ‐ 107, quench rate (17000 ‐75000 K/s), and quench stoichiometry (27 ‐ 84). which was defined as the molar ratio of steam to SiO. The thickening and thixotropic ability of the powders increased with increasing quench rate and decreasing pre‐quench supersaturation. This was due to an increase in specific surface area. Use of large H2 O/SiO ratios caused a high degree of surface hydroxylation.
Solubility of argon in acetone + water mixed solvent at 288.15, 298.15 and 308.15 K
Authors: Yamamoto Hideki , Tokunaga Junji , Koike Keiji
Published: March 2009

Solubilities of argon were determined in acetone + water mixed solvent over the full range of composition using a static method. The gas solubilities were measured at three temperatures of 288.15, 298.15 and 308.15 K. The solubility dependence on the temperature in the mixed solvent was measured and discussed, and the similarity between excess quantities of mixed solvent and those of gas solubilities was examined.

The order of gas solubility of argon in acetone + water mixed solvent at the three different temperatures was 288. 15 > 298.15 > 308.15 K in the composition range of 0 ≤ x22 ≤ 0.15. However, the reverse relationship with temperature was observed in the range of composition of 0.15 < x2 ≤ 1.0. For all solubility curves, maximum and minimum values of solubility were observed at lower temperatures, but not at higher temperatures. Furthermore, the excess Ostwald coefficients on the basis of volume fraction which express the non‐ideality of gas solubility in non‐ideal solutions were defined, and they were expressed by a polynomial equation of the Redlich‐Kister (1948) type.
Wall‐to‐bed heat transfer in three‐phase fluidized beds of low density particles
Authors: Nore O. , Wild G. , Briens C. L. , Margaritis A.
Published: March 2009

Bed‐to‐wall heat transfer was measured in three‐phase fluidized beds under conditions typical of biochemical process applications. The thermal resistance of the fluidized bed, which was significant in the absence of gas, became negligible when gas was introduced. Decreasing the particle density at constant gas and liquid velocity increased the bed‐to‐wall heat transfer coefficient.

Previously published heat transfer correlations were used and gave poor predictions of our data. A new correlation was developed which predicted very well all the heat transfer coefficient results in this paper.
Adsorption of sodium dodecyl sulphate on cassiterite surface
Authors: González‐Martín M. L. , Janczuk B. , Bruque J. M. , Dorado‐Calasanz C.
Published: March 2009

Measurements of the adsorption of sodium dodecyl sulphate (SDS) onto cassiterite were made. It was found that at SDS concentrations below 10 −3 mol/L the adsorption depended on the manner of preparation of the cassiterite and the pH of solution. However, the adsorption isotherms showed a point of inflection at l0 −3 mol/L corresponding to an occupied area per molecule of about 0.8 nm2. This value is close to the surface area covered by one dodecyl sulphate ion (DS −) as evaluated from the molecular structure of SDS. Near the critical micelle concentration (cmc), a plateau was found which corresponded to the adsorption of two statistical monolayers of DS − ions vertically oriented to the surface.
Particle velocity profiles and solid flow patterns in spouted beds
Authors: He Y.‐L. , Qin S.‐Z. , Lim C. J. , Grace J. R.
Published: March 2009

A fibre optic probe system was used to measure the profiles of vertical particle velocities in the spout and the fountain of a half‐column and a full‐column spouted bed. In addition, a fibre optic image probe was employed to measure vertical particle velocity profiles in the annulus of the full‐column. In the spout, radial profiles of vertical particle velocities were of near Gaussian distribution. Particle velocities along the spout axis in the half‐column were 30% lower than in the full‐column under identical operating conditions. In the half column, particle velocities adjacent to the front plate were approximately 24% lower than a few millimeters away. The fountain core expanded suddenly near the bed surface and then gradually contracted with height. The model of Grace and Mathur (1978) gave good predictions of fountain heights for the full‐column. In the annulus region, there was a 28% difference between particle velocities adjacent to the column wall and those only 2 mm away. The integrated upward solids mass flow in the spout and the downward solids flow in the annulus matched well at different bed levels.
An optimal operational strategy for wood in batch drying system
Authors: Hwang Bing Joe , Wang Cheng‐Hsing , Liou Ching‐Tein
Published: March 2009

A complete model based on the wood drying mechanism and incorporating a multi‐period operation was established for wood in batch drying systems. Both energy savings and improvement of wood quality were obtained by an optimal strategy proposed in this study. Energy saving was indicated by the numerical results to be roughly 22.5% for drying of soft wood under the conditions of a given drying time and final moisture content. The gradient of moisture content within the dried wood could be minimized for the sake of enhancing the quality of wood by applying the proposed operational model.
Methanol synthesis under periodic operation: An experimental investigation
Authors: Chanchlani K. G. , Hudgins R. R. , Silveston P. L.
Published: March 2009

Experiments have been conducted on Cu/ZnO and Cu/ZnO/Al2O3 catalysts at 225°C and 2.86 MPa in an isothermal, differential packed bed reactor to identify promising periodic operations strategies and find cycling variables which give the largest improvement in the synthesis rate relative to steady state. Modulating the H2 and CO2 concentrations appears to be the best strategy. However, the increased rate under composition modulation was insensitive to cycle period, amplitude and split in the cycle period range from 2 to 30 min. Higher methanol yield resulted from the suppression of the reverse water gas shift reaction. Higher rates under cycling arise from structural or compositional changes to the catalyst surface.
Flow characteristics of hyperboloid stirrers
Authors: Nouri J. M. , Whitelaw J. H.
Published: March 2009

The flows in a fully‐baffled vessel with a diameter T = 144 mm driven by hyperboloid stirrers of diameters D = 773 and 27/3 have been visualised and characterised by local measurements of velocity and turbulence and by power number. The results were obtained for a range of rotational speeds from 6 to 40 rev/s. The visualisation showed that the larger stirrer gave rise to a radial jet and that the smaller stirrer formed a jet inclined towards the base of the vessel so that there was a tendency for the system of two vortices, one above and one below the jet, to give way to a single vortex as the clearance between the stirrer and the base of the vessel was reduced. The velocity measurements revealed bulk‐flow values an order of magnitude less than that of the maximum radial velocity in the jet, that the maximum radial velocity was 24% of the circumferential velocity of the tip of the stirrer, and that the radial velocities were proportional to the rotational speed.

The flows generated by the hyperboloid stirrer were less vigorous than those of Rushton impellers of similar radius and were associated with power numbers 28 times less. The power number did not vary with rotational speed or with clearance within the measured range. The contrast with propeller and disc stirrers is less pronounced, but the hyperbolic profile is likely to find application and the present results provide a basis for choice.
Modeling of porous radiant burners with large extinction coefficients
Authors: Escobedo F. , Viljoen H. J.
Published: March 2009

A comparative study of numerical and analytical results for a porous radiant burner (PRB) is presented. It is shown that the analytical method captures all the features of the system and can be used for quantitative applications. Two solutions are found, one is located close to the inlet of the burner and the second one is close to the outlet. The effects of the molar flow rate, the interphase heat transfer coefficient (hs) and the location of the flame in the matrix, on the radiation efficiency (RE) of the burner are studied. Local maxima in the RE vs. hs curves indicate that intermediate values of hs will be the optimum choice. Other trends are also analyzed and some recommendations are made.
Chemical absorption of mercaptan in an aerosol operated loop reactor
Authors: Kube C. H. , Blume T. , Prüss J. , Warnecke H.‐J.
Published: March 2009

A mechanistic mathematical model for the chemical absorption of mercaptan in sodium hypochlorite solution has been derived. In order to describe the process adequately, a semi‐verified complex scheme of the involved kinetic reactions based on stopped‐flow measurements with UV‐detection has been implemented. The overall system of differential equations has been solved numerically. For some asymptotic cases, approximation formulae are given. The process has been carried out in an aerosol operated jet loop reactor which is characterized by high interfacial areas at low liquid flow rates. Fitting the model solution to the experimentally obtained conversion data enabled determination of the unknown hydrodynamic parameters. By means of a sensitivity analysis, the influences of the different parameters are discussed.
Simultaneous hydrolysis and fermentation of pulp mill primary clarifier sludge
Authors: Duff Sheldon J. B. , Moritz John W. , Andersen Kari L.
Published: March 2009

Bioconversion of sludge from the primary clarifier of a sulphite pulping operation to ethanol offers a number of advantages over conventional disposal options. The amount of material which must be disposed of is reduced while, at the same time, salable and environmentally friendly fuel‐ethanol is produced. In this study, primary clarifier sludge (PCS) was shown to be hydrolysed to produce fermentable sugars at a rate proportional to enzyme loading. Initial (1 hour) hydrolysis rates as high as 12.6 g reducing sugar/L · h were observed at an initial enzyme loading of 10 filter paper units (FPU)/g. Hydrolysis was inhibited by spent sulphite liquor (SSL), an inhibition which could be completely overcome by fermenting the SSL to remove sugars. Surfactants were found to only marginally improve the production of sugars. To reduce the deleterious effects of end product inhibition, single stage simultaneous hydrolysis and fermentation (SHF) was carried out using cellulase enzymes and Saccharomyces cerevisiae.
Molecular transport of organic esters and ketones into fluoropolymer membranes
Authors: Aminabhavi T. M. , Munnolli R. S.
Published: March 2009

The effect of different fluorine contents of DuPont VITON fluoropolymers and their transport characteristics in the presence of phenyl acetate, diethyl oxalate, diethyl malonate, diethyl succinate, acetone, methyl ethyl ketone and methyl iso‐butyl ketone has been investigated over the temperature interval of 25−60°C. The average values of diffusion coefficients are obtained from the Fickian relation and the molecular transport is found to follow an anomalous behavior. Kinetic rate constants and pentration velocities are also calculated. The experimental results and the calculated quantities are studied in terms of polymer‐solvent interactions.
Optimal averaging level control for the tennessee eastman problem
Authors: Ye Nan , Mcavoy Thomas J. , Kosanovich Karlene A. , Piovoso Michael J.
Published: March 2009

This paper focuses on an industrial test problem, the Tennessee Eastman problem. The Tennessee Eastman process is moved to three operation modes with 90/10, 50/50 and 10/90 product G/H ratios. The base control system proposed in an earlier paper can properly control the process at all the three operation modes. Optimal averaging level control is added to the base control to improve the control of product flow during random and step feed disturbances. A new implementation of the optimal feedback averaging control algorithms (McDonald et al., 1986) is presented in order to deal with random disturbances. Simulation results show that control of product flow rate is significantly improved by using the optimal feedback averaging level control at all three operation modes.
The possible negative impacts of volunteer tourism
Authors: Guttentag Daniel A.
Published: March 2009

Volunteer tourism is an increasingly popular form of travel that is attracting growing research attention. Nevertheless, existing research has focused primarily on the benefits of volunteer tourism, and many studies have simply involved profiling volunteers or investigating their motivations. However, there are numerous possible negative impacts of volunteer tourism that deserve increased attention from both researchers and project managers: a neglect of locals' desires, a hindering of work progress and completion of unsatisfactory work, a disruption of local economies, a reinforcement of conceptualisations of the ‘other’ and rationalisations of poverty, and an instigation of cultural changes. Copyright © 2009 John Wiley & Sons, Ltd.
Analysis of Stem Cell Lineage Progression in the Neonatal Subventricular Zone Identifies EGFR+/NG2− Cells as Transit-Amplifying Precursors
Authors: Cesetti Tiziana , Obernier Kirsten , Bengtson C. Peter , Fila Tatiana , Mandl Claudia , Hölzl-Wenig Gabriele , Wörner Kerstin , Eckstein Volker , Ciccolini Francesca
Published: March 2009

In the adult subventricular zone (SVZ), astroglial stem cells generate transit-amplifying precursors (TAPs). Both stem cells and TAPs form clones in response to epidermal growth factor (EGF). However, in vivo, in the absence of sustained EGF receptor (EGFR) activation, TAPs divide a few times before differentiating into neuroblasts. The lack of suitable markers has hampered the analysis of stem cell lineage progression and associated functional changes in the neonatal germinal epithelium. Here we purified neuroblasts and clone-forming precursors from the neonatal SVZ using expression levels of EGFR and polysialylated neural cell adhesion molecule (PSANCAM). As in the adult SVZ, most neonatal clone-forming precursors did not express the neuroglia proteoglycan 2 (NG2) but displayed characteristics of TAPs, and only a subset exhibited antigenic characteristics of astroglial stem cells. Both precursors and neuroblasts were PSANCAM+; however, neuroblasts also expressed doublecortin and functional voltage-dependent Ca2+ channels. Neuroblasts and precursors had distinct outwardly rectifying K+ current densities and passive membrane properties, particularly in precursors contacting each other, because of the contribution of gap junction coupling. Confirming the hypothesis that most are TAPs, cell tracing in brain slices revealed that within 2 days the majority of EGFR+ cells had exited the cell cycle and differentiated into a progenitor displaying intermediate antigenic and functional properties between TAPs and neuroblasts. Thus, distinct functional and antigenic properties mark stem cell lineage progression in the neonatal SVZ.

Disclosure of potential conflicts of interest is found at the end of this article.
Dax-1 Knockdown in Mouse Embryonic Stem Cells Induces Loss of Pluripotency and Multilineage Differentiation
Authors: Khalfallah Olfa , Rouleau Matthieu , Barbry Pascal , Bardoni Barbara , Lalli Enzo
Published: March 2009

Dax-1 (Nr0b1) is an orphan member of the nuclear hormone receptor superfamily that has a key role in adrenogonadal development and function. Recent studies have also implicated Dax-1 in the transcriptional network controlling embryonic stem (ES) cell pluripotency. Here, we show that Dax-1 expression is affected by differentiating treatments and pharmacological activation of β-catenin–dependent transcription in mouse ES cells. Furthermore, Dax-1 knockdown induced upregulation of multilineage differentiation markers, and produced enhanced differentiation and defects in ES viability and proliferation. Through RNA interference and transcriptome analysis, we have identified genes regulated by Dax-1 in mouse ES cells at 24 and 48 hours after knockdown. Strikingly, the great majority of these genes are upregulated, showing that the prevalent function of Dax-1 is to act as a transcriptional repressor in mouse ES cells, as confirmed by experiments using the Gal4 system. Genes involved in tissue differentiation and control of proliferation are significantly enriched among Dax-1–regulated transcripts. These data show that Dax-1 is an essential element in the molecular circuit involved in the maintenance of ES cell pluripotency and have implications for the understanding of stem cell function in both physiological (adrenal gland) and clinical (Ewing tumors) settings where Dax-1 plays a pivotal role in development and pathogenesis, respectively.

Disclosure of potential conflicts of interest is found at the end of this article.
The disorderly study of ordered recruitment
Authors: Biddick Rhiannon , Young Elton T.
Published: March 2009

Activated transcription in eukaryotes requires the aid of numerous co‐factors to overcome the physical barriers chromatin poses to activation, bridge the gap between activators and polymerase, and ensure appropriate regulation. S. cerevisiae has long been a model organism for studying the role of co‐activators in the steps leading up to gene activation. Detailed studies on the recruitment of these co‐activators have been carried out for more than a dozen promoters. Taking a step back to survey these results, however, suggests that there are few generalizations that could be used to guide future studies of uncharacterized promoters. Copyright © 2009 John Wiley & Sons, Ltd.
A roadmap for the prevention of dementia II: Leon Thal Symposium 2008
Authors: Khachaturian Zaven S.
Published: March 2009

This document proposes an array of recommendations for a National Plan of Action to accelerate the discovery and development of therapies to delay or prevent the onset of disabling symptoms of Alzheimer's disease. A number of key scientific and public‐policy needs identified in this document will be incorporated by the Alzheimer Study Group into a broader National Alzheimer's Strategic Plan, which will be presented to the 111th Congress and the Obama administration in March 2009. The Alzheimer's Strategic Plan is expected to include additional recommendations for governance, family support, healthcare, and delivery of social services.
The effect of dacryocystorhinostomy on mucociliary function
Authors: Okuyucu Semsettin , Akoglu Ertap , Oksuz Huseyin , Gorur Hatice , Dagli Safak
Published: March 2009

Objective

External dacryocystorhinostomy is suspected to cause mucociliary dysfunction by affecting ciliary activity and quality of the mucus. We hypothesized that patients who undergo endoscopic dacryocystorhinostomy may also experience mucociliary dysfunction. We evaluated the effects of surgery on mucociliary clearance time in patients who underwent endoscopic dacryocstorhinostomy and external dacryocstorhinostomy.

Study Design

A prospective controlled study.

Subjects and Methods

Forty‐four patients were studied: 22 had undergone one‐sided endoscopic surgery and 22 had undergone one‐sided external surgery for nasolacrimal duct obstruction. Nonoperated sides of the both groups were remained as controls. The saccharin test was used to evaluate the mucociliary clearance time of the both sides.

Results

Dacryocystorhinostomy, results in prolonged mucociliary clearance times either endoscopic or external approach is performed (P < 0.001, paired t test). There was no significant difference between the mucociliary clearance times after endoscopic and external dacryocystorhinostomy (P = 0.22, Student's t test).

Conclusion

Dacryocystorhinostomy impairs mucociliary function independent of the type of surgery.
Balloon sinuplasty for the surgical management of immunocompromised and critically ill patients with acute rhinosinusitis
Authors: Wittkopf Maria L. , Becker Samuel S. , Duncavage James A. , Russell Paul T.
Published: March 2009

Objective

The purpose of this study was to review use of balloon sinuplasty for surgical treatment in critically ill patients with acute sinusitis.

Study Design

Case series with chart review.

Subjects and Methods

Patients who underwent balloon sinuplasty between October 2007 and March 2008 were identified. Medical records of the subset of patients who were immunocompromised or otherwise critically ill were analyzed.

Results

Thirty‐one patients underwent balloon sinuplasty at our institution between October 2007 and March 2008. We identified five critically ill patients with sinus disease within this group. Patient ages ranged from 15 to 51 years with no sex preponderance. All patients had focal findings on a sinus CT scan. In all cases, purulent drainage was noted intraoperatively. All patients returned to baseline health meeting discharge criteria after treatment.

Conclusion

Balloon sinuplasty represents a potentially less invasive surgical option than standard Functional Endoscopic Sinus Surgery (FESS) and should be considered in the treatment of critically ill or immunocompromised patients.
Microatoll record for large century-scale sea-level fluctuations in the mid-Holocene
Authors: Yu Ke-Fu , Zhao Jian-Xin , Done Terry , Chen Te-Gu
Published: March 2009

Coral microatolls have been long used as precise indicators of past sea level, but their use for precise definition of detailed sea-level fluctuations is still rare. Here we report twelve high-precision thermal ionization mass spectrometric 230Th ages for twelve rims of five mid-Holocene microatolls from an emerged reef terrace at Leizhou Peninsula, northern South China Sea. This is a tectonically stable area, enabling us to reconstruct both the timing and trajectory of local sea-level fluctuations accurately. The elevations of these microatoll rims and cores were accurately determined relative to the surface of modern living microatolls at the same site. The results indicate that the sea level during the period of 7050–6600 yr bp (years before AD 1950) was about 171 to 219 cm above the present, with at least four cycles of fluctuations. Over this 450 yr interval, sea level fluctuated by 20–40 cm on century scales.
Early human impact in the forest ecotone of southern High Asia (Hindu Kush, Himalaya)
Authors: Miehe Georg , Miehe Sabine , Schlütz Frank
Published: March 2009

The vegetation of the treeline ecotone of the southern declivity of arid High Asia (Hindu Kush, northern areas of Pakistan; Himalaya, northern central Nepal) is dominated by hedgehog-like open dwarf shrublands of thorny cushions. Since climatically sensitive ecotones are always also sensitive to human impact, the question arises whether the current lack of forests is a result of the Subboreal climate decline or of human impact. Due to inadequate knowledge of the pollen flora and of ecological indicator values of the plants, pollen analyses in High Asia have mainly been limited to the regional verification of globally known climatic impulses. However, the role of human impact on regional vegetation patterns has been widely neglected. We postulate that today's open dwarf shrublands replace woodlands and forests. Isolated vigorous juniper trees and successful reforestation appear to confirm our hypothesis. An abrupt decline of Pinus forests before 5700 and 5400 ka cal yr BP can be demonstrated. As the first indicator pollen of human impact appeared at both sites synchronous with the forest pollen decline, we infer human impact to be a more decisive cause for this environment change superimposing the effects of a climatic deterioration. The forests were displaced by open dwarf shrublands.
A comparison of alternative plant mixes for conservation bio-control by native beneficial arthropods in vegetable cropping systems in Queensland Australia
Authors: Qureshi S.A. , Midmore D.J. , Syeda S.S. , Reid D.J.
Published: March 2009

Cucurbit crops host a range of serious sap-sucking insect pests, including silverleaf whitefly (SLW) and aphids, which potentially represent considerable risk to the Australian horticulture industry. These pests are extremely polyphagous with a wide host range. Chemical control is made difficult due to resistance and pollution, and other side-effects are associated with insecticide use. Consequently, there is much interest in maximising the role of biological control in the management of these sap-sucking insect pests. This study aimed to evaluate companion cropping alongside cucurbit crops in a tropical setting as a means to increase the populations of beneficial insects and spiders so as to control the major sap-sucking insect pests. The population of beneficial and harmful insects, with a focus on SLW and aphids, and other invertebrates were sampled weekly on four different crops which could be used for habitat manipulation: Goodbug Mix (GBM; a proprietary seed mixture including self-sowing annual and perennial herbaceous flower species); lablab (Lablab purpureus L. Sweet); lucerne (Medicago sativa L.); and niger (Guizotia abyssinica (L.f.) Cass.). Lablab hosted the highest numbers of beneficial insects (larvae and adults of lacewing (Mallada signata (Schneider)), ladybird beetles (Coccinella transversalis Fabricius) and spiders) while GBM hosted the highest numbers of European bees (Apis mellifera Linnaeus) and spiders. Lucerne and niger showed little promise in hosting beneficial insects, but lucerne hosted significantly more spiders (double the numbers) than niger. Lucerne hosted sig-nificantly more of the harmful insect species of aphids (Aphis gossypii (Glover)) and Myzus persicae (Sulzer)) and heliothis (Heliothis armigera Hübner). Niger hosted significantly more vegetable weevils (Listroderes difficillis (Germar)) than the other three species. Therefore, lablab and GBM appear to be viable options to grow within cucurbits or as field boundary crops to attract and increase beneficial insects and spiders for the control of sap-sucking insect pests. Use of these bio-control strategies affords the opportunity to minimise pesticide usage and the risks associated with pollution.
Child L2 development: A longitudinal case study on Voice Onset Times in word-initial stops
Authors: SIMON ELLEN
Published: March 2009

This paper reports the results of a longitudinal case study examining the acquisition of the English voice system by a three-year-old native speaker of Dutch. The study aims to examine whether the child develops two different phonetic systems or uses just one system for both languages, and compares the early L2 acquisition process with L1, simultaneous bilingual and late L2 acquisition. The results reveal that the child successfully acquires the English contrast between short-lag and long-lag stops, but gradually changes the Dutch system, which contrasts prevoiced with short-lag stops, into the direction of the English system.
Inhibitory Effect of Astraxanthin Combined with Flavangenol® on Oxidative Stress Biomarkers in Streptozotocin-Iduced Diabetic Rats
Authors: Nakano Masako , Orimo Natsumi , Katagiri Nakako , Tsubata Masahito , Takahashi Jiro , Van Chuyen Nguyen
Published: March 2009

In this study, the effect of dietary antioxidants, such as astaxanthin and Flavangenol®, and a combination of both, in counteracting oxidative stress in streptozotocin-induced diabetes was investigated. Streptozotocin-induced diabetic rats were divided into four groups: control, astaxanthin, Flavangenol, and combined astaxanthin and Flavangenol (mix group). Each group other than the control group was fed with an astaxanthin diet (0.1 g/kg), Flavangenol diet (2.0 g/kg), or an astaxanthin (0.1 g/kg)-Flavangenol (2.0 g/kg) mixture diet, respectively. After 12 weeks of feeding, the results showed that the lipid peroxide levels of plasma and lens and the plasma triglyceride (TG) level in the mix group were significantly decreased by 44%, 20%, and 20%, respectively, compared with the control group. In the mix group, lipid peroxidation was also significantly reduced by 70% in the liver and 20% in the kidney compared with the control group. Furthermore, the level of urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) in the mix group was significantly lower, 36%, than the control group. The α-tocopherol concentrations in the plasma, liver, and kidney in the astaxanthin and mix groups were significantly higher, 3-9 times, than in the control group. The degree of cataract formation in the Flavangenol and mix groups tended to be lower than the control group. These results indicate that the combination of astaxanthin with Flvangenol has an improved protective effect on oxidative stress associated with streptozotocin-induced diabetes than either agent used alone. Thus, this combination may be beneficial in preventing the progression of diabetic complications.
Haploinsufficiency and acquired loss of Bcl11b and H2AX induces blast crisis of chronic myelogenous leukemia in a transgenic mouse model
Authors: Nagamachi Akiko , Yamasaki Norimasa , Miyazaki Kazuko , Oda Hideaki , Miyazaki Masaki , Honda Zen‐ichiro , Kominami Ryo , Inaba Toshiya , Honda Hiroaki
Published: March 2009

Chronic myelogenous leukemia (CML) is a hematological malignancy that begins as indolent chronic phase (CP) but inevitably progresses to fatal blast crisis (BC). p210BCR/ABL, a chimeric protein with enhanced kinase activity, initiates CML CP, and additional genetic alterations account for progression to BC, but the precise mechanisms underlying disease evolution are not fully understood. In the present study, we investigated the possible contribution of dysfunction of Bcl11b, a zinc‐finger protein required for thymocyte differentiation, and of H2AX, a histone protein involved in DNA repair, to the transition from CML CP to BC. For this purpose, we crossed CML CP‐exhibiting p210BCR/ABL transgenic (BAtg/–) mice with Bcl11b heterozygous (Bcl11b+/–) mice and H2AX heterozygous (H2AX+/–) mice. Interestingly, p210BCR/ABL transgenic, Bcl11b heterozygous (BAtg/–Bcl11b+/–) mice and p210BCR/ABL transgenic, H2AX heterozygous (BAtg/–H2AX+/–) mice frequently developed CML BC with T‐cell phenotype and died in a short period. In addition, whereas p210BCR/ABL was expressed in all of the leukemic tissues, the expression of Bcl11b and H2AX was undetectable in several tumors, which was attributed to the loss of the residual normal allele or the lack of mRNA expression. These results indicate that Bcl11b and H2AX function as tumor suppressor and that haploinsufficiency and acquired loss of these gene products cooperate with p210BCR/ABL to develop CML BC. (Cancer Sci 2009; 100: 1219–1226)