bluuebunny/crossref_metadata_2025 huggingface dataset:
Averaged and time‐resolved, full‐field (three‐dimensional), measurements of unsteady opposed jets
Authors: Zhao Yang , Brodkey Robert S.
Published: March 2009

Full‐field, time‐resolved, velocity vector information was obtained for an opposing jet reactor. The velocities were measured by particle tracking velocimetry (PTV) over a range of jet Reynolds numbers (200–5000). The main results reported are for a Reynolds number of 200. Graphical representation of the extensive data fields cannot be conveniently reported here; however, examples are provided. A more thorough presentation is possible by using color and dynamic representations and these are provided at the URL (Uniform Resource Locator, i.e., the address for a location on the Internet) cited in Zhao and Brodkey (1998). It is important to emphasize that the velocity fields presented in this paper are experimental.
Validation of CFD simulations of a stirred tank using particle image velocimetry data
Authors: Sheng Jian , Meng Hui , Fox Rodney O.
Published: March 2009

Methods for validating CFD simulations based on the Reynolds Average Navier‐Stokes equation (RANS) against Particle Image Velocimetry (PIV) measurements are investigated and applied to one of the most common problems in the chemical process industry — the prediction of flow field in a stirred vessel. A total of 1024 sequential instantaneous 2D velocity fields along the central axial plane of a stirred vessel with a P‐4 axial impeller are obtained through PIV measurement. From the PIV data, the mean velocity, turbulent kinetic energy, Reynolds stresses and dissipation rate fields are extracted. By introducing several tools to quantify the similarities and differences between two‐dimensional fields, CFD predictions of the flow field are validated against PIV data. Furthermore, using PIV and LDV data, the effect of boundary conditions on CFD simulation results is examined. The effect of different Reynolds stress closures on the flow prediction is also studied.
Direct prediction of the flows induced by a propeller in an agitated vessel using an unstructured mesh
Authors: Naude Isabelle , Xuereb Catherine , Bertrand Joél
Published: March 2009

The direct simulation of impellers with complex geometrical shapes has not yet been presented. The unstructured mesh with a multiple reference frame approach has to be used to model the system with complete fidelity. The ability of a new CFD unstructured package is investigated in a cylindrical baffled tank stirred by an industrial LUMPP LB propeller in turbulent flow. Different positions of the blade relative to the side‐wall baffles have been computed to study the time‐dependent flow fields. The computational results compared favourably with experimental LDA data, with pumping number and power number, but a great care should be put on the mesh quality since results are extremely sensitive. It is concluded that the multiple reference frame approach is suitable to design impeller optimized for a given application.
Gas chromatography — mass spectrometric determination of unsymdimethylhydrazine in soil and water by derivatization with aromatic aldehydes
Authors: Cathum Shamil , Atamaniouk Vladimir , Ananieva Lioudmila , Ladanowski Caroline , Whittaker Harry
Published: March 2009

A gas chromatography — mass spectrometric method for determination of unsymdimethylhydrazine (UDMH) in soil and water has been developed. The method is based on derivatization of UDMH with 2‐nitrobenzaldehyde, 4‐nitrobenzaldehyde, 4‐chlorobenzaldeyhde, 4‐cyanobenzaldehyde, 4‐dimethyaminobenzaldehyde, benzaldehyde and furfuraldehyde, followed by analysis of the derivative using gas chromatography — mass spectrometry. The effect of ambient air and antioxidants (pyrogallol and TiCl3) to absorb dissolved oxygen from the reagents has been investigated. The method proves to be useful for UDMH analysis in soil and water, and has been used for environmental site assessment at a former missile base in Ukraine.
RTD studies in trickle bed reactors packed with porous particles
Authors: Saroha Anil K. , Nigam K. D. P. , Saxena Alok K. , Dixit Lalji
Published: March 2009

The residence time distribution (RTD) for liquid phase in a trickle bed reactor (TBR) has been experimentally studied for air‐water system. Experiments were performed in a 15.2 cm diameter column using commerical alumina extrudates with D/dp ratio equal to 75 to eliminate the radial flow differences. The range of liquid and gas flow rates covered was 3.76 < ReL < 9.3 and 0 < ReG < 2.92. The axial dispersion model was used to compute axial dispersion coefficient. The effect of liquid and gas flow rates on total liquid holdup and axial dispersion was investigated. The total liquid holdup has been correlated to liquid and gas flow rates.
The kinetics of sorption of basic dyes from aqueous solution by sphagnum moss peat
Authors: Ho Y. S. , Mckay G.
Published: March 2009

The kinetics of sorption of three basic dyes, namely, Chrysoidine (BO2), Astrazon Blue (BB3) and Astrazone Blue (BB69) onto sphagnum moss peat have been investigated. The study focuses on the application of three sorption kinetic models for predicting the uptake of basic dyes. The sorption behaviour is found to be second order, based on the assumption of a pseudo‐second order mechanism. The rate constant of sorption, the equilibrium capacity and initial sorption rate with the effect of various peat doses and initial dye concentrations have also been predicted.
High concentrations ammonia removal by the cyanobacterium plectonema boryanum in a photobioreactor system
Authors: Prakash Anand , Margaritis Argyrios , Saunders Richard C. , Vijayan Sivaraman
Published: March 2009

The potential application of the cyanobacterium Plectonema boryanum was investigated for the removal of ammonia from aqueous solution to meet the target concentration of below 0.02 mg/L free ammonia. This method can be applied as a final polishing step in a series of wastewater treatment steps to reduce the ammonia concentration to drinking water levels. The experiments were conducted in a 2 L photobioreactor using batch and semi‐batch modes of operation. The effect of important growth parameters such as temperature, light intensity and pH were investigated to identify their relative significance in a batch photobioreactor. Concentrations of ammonia in aqueous samples were varied up to 420 mg/L to study ammonia removal rates and growth of the cyanobacterium. The ammonia removal rates and maximum growth rates of the cyanobacterium were calculated and compared with other studies reported in literature. Repeated fed‐batch experiments demonstrate the viability of the process to reduce free ammonia in aqueous solutions to less than 0.02 mg/L. The results of this study demonstrate the potential application of cyanobacteria technology for ammonia removal at 100 mg/L of total ammonia and greater.
A numerical study of steady incompressible newtonian fluid flow over a disk at moderate reynolds numbers
Authors: Munshi Basudeb , Chhabra Rajendra P. , Ghoshdastidar Partha Sarathi
Published: March 2009

The hydrodynamic behaviour of a single thin disk settling steadily, broad face‐wise, in an incompressible Newtonian fluid has been investigated by solving the Navier‐Stokes equations numerically using an iterative procedure. The finite difference method has been used to map out the complete flow domain in terms of the values of the stream function and vorticity. Finally, the drag coefficient was evaluated by considering the energy dissipation. Extensive results on drag for a disk of thickness to diameter ratio of 0.05 show excellent agreement with the experimental, as well as, previous scant numerical results in the range 1 ≤ Re ≤ 100.
A radial void fraction correlation for packed bed tubes
Authors: Mueller Gary E.
Published: March 2009

The radial void fraction distribution of equal sized spheres in cylindrical packed bed tubes with low diameter aspect ratios (1 ≤ D/d ≤ 2) is determined from the spheres' center coordinates, the local radial void faction and the radial positions within the tubes. A correlation that closely predicts the local radial void fraction at a radial position is determined from the radial void fraction distributions. The correlation is a function of the diameter aspect ratio and the radial position in the cylindrical packed bed tubes.
The modified dynamic model of a riser type fluid catalytic cracking unit
Authors: Malay Pathanjali , Rohani Sohrab , Milne Bruce J.
Published: March 2009

The dynamic model developed by Ali and Rohani (1997) to describe the transient behavior of a fluid catalytic cracking (FCC) unit is modified (i) to incorporate the effect of volumetric expansion of the feed and product gases flowing in the riser reactor (ii) to consider the enhancement of mass and heat transfer coefficients due to high turbulence in the regenerator and (iii) to model the reactor and stripper as a continuous stirred tank. The modified model is validated using steady‐state plant data from an industrial unit (Consumer's Co‐operative Refineries Ltd., Regina, SK) and the results are found to be in good agreement.
Application of dynamic pressure probe technique to characterize a circulating fluidized bed
Authors: Pärssinen Janne H. , Hagelberg Pasi , Eilos Isto , Aittamaa Juhani
Published: March 2009

In this study a small diameter dynamic pressure probe was used to measure the flow characteristics and the annulus thickness in a circulating fluidized bed. The nonhomogeities of fluidization in the vertical and radial directions have been measured and the results are presented in a new way, as dynamic pressure against time. The diagrams reveal that the flow can, under certain conditions, exhibit significant reversals in the core areas. Particle size distribution in the vertical direction was also studied by using the quick‐closing valve technique. The pilot scale riser was cylindrical and the particles were typical FCC catalyst.
From hygroscopic single particle to batch fluidized bed drying kinetics
Authors: Burgschweiger Jens , Groenewold Hans , Hirschmann Carola , Tsotsas Evangelos
Published: March 2009

A new normalization concept for convective drying of hygroscopic particulates is introduced. Both, intraparticle drying kinetics and sorption equilibrium are considered separately, and integrated into a new heterogeneous fluid bed model for coupled heat and mass transfer. Experiments were carried out using spherical γ‐Al2O3 particles. Sorption isotherms, as well as drying curves, for single particles and fluidized beds have been measured. Batch fluid bed drying curves appear to be predictable on the basis of single particle and material equilibrium data and with the help of the model. All model parameters are directly taken, or estimated from fluidization literature, without any fitting.
MTBE synthesis in a novel riser simulator
Authors: De Lasa Hugo , Fournier Pierre , Prakash Anand , Solh Tarek El
Published: March 2009

MTBE synthesis, from methanol and iso‐butylene, is studied in a novel Riser Simulator using a ZSM‐5 catalyst. Conditions selected for the operation of the Riser Simulator unit are as follows: 1‐5 catalyst/reactant ratios, 80 to 160°C temperatures, 1.09 methanol/iso‐butylene mol ratio, 25 to 34 kPa methanol partial pressures and 10 to 120 s reaction times. Injection of methanol, with enough time for the methanol to reach adsorption equilibrium, followed by an isobuty‐lene injection is found to be the best operating mode to achieve 100% iso‐butylene selectivity toward MTBE with 4 to 6.8% isobutylene conversions. With the gathered experimental data, a reaction rate model based on the Rideal‐Eley kinetic model is successfully developed.
Preparation of the Mn/γ‐Al2O3 acceptor for high temperature regenerative H2S removal
Authors: Liang Bin , Korbee Rob , Gerritsen Albert W. , Van Den Bleek Cor M.
Published: March 2009

An alumina supported manganese acceptor can be used for high temperature regenerative removal of hydrogen sulfide. Such an acceptor was prepared by a wet impregnation method on a 10 kg scale. A porous alumina carrier with a size of 50 to 70 microns was impregnated with a manganese acetate solution. The impregnation slurry was centrifuged and dried in a microwave oven. The impregnation parameters and drying conditions were investigated. It is shown that this impregnation process is dominated by the solution penetrating the pores. The manganese loading of the acceptor was estimated based on the concentration of the impregnating solution. This showed a good agreement with the results of AAS (Atom Absorption Spectrometer) measurements. The microwave drying time needed was calculated by a heat balance over the drying system. The preparation exhibited a good reproducibility and the acceptors prepared have better dispersion and less initial deactivation.
A sporulation kinetic model for batch growth of B. thuringiensis
Authors: Rivera David , Margaritis Argyrios , de Lasa Hugo
Published: March 2009

B. thuringiensiscells evolve from vegetative cells to sporulated cells during batch growth. As a result, the classical model based on an exponential binary fission and the Monod equation has intrinsic limitations to describe the biomass concentration. A new kinetic model accounting for the spore formation process is presented in this study. This model considers that only the cells without a spore are able to contribute to the cell growth. This model also incorporates the spore formation process using a spore formation step and a specific spore formation rate constant. Classical and new model predictions are compared with batch experimental data. Results demonstrate that the classical model is unable to predict the experimental data and this is particularly true from the middle of the transition stage on. In contrast, the new sporulation kinetic model is able to predict the experimental data more accurately for the complete time span of the batch culture.
Thermal deactivation studies of coconut shell pyrolysis
Authors: Bandyopadhyay Swati , Chowdhury Ranjana , Biswas Gopal Krishna
Published: March 2009

The kinetics of pyrolysis of predried coconut shell sample has been investigated in the temperature range of 523 K to 1023 K in an inert atmosphere by captive sample technique. A kinetic scheme has been proposed where two parallel reactions are given for the production of volatiles and char. The reaction rate constants are found to decrease with high temperatures above 673 K due to chemical and physical changes of the reactant during devolatilisation reaction. Several deactivation models have been proposed to give good agreement with the experimental data.
Correlations for the particle deposition rate accounting for lift forces and hydrodynamic mobility reduction
Authors: Adomeit Philipp , Renz Ulrich
Published: March 2009

A numerical procedure is presented which allows one to predict the deposition rate of microparticles suspended in a liquid flow onto the confining walls. Particle transport is not only diffusive but also affected by hydrodynamically induced lift force and reduced particle mobility. An appropriate expression for the lift‐induced migration is introduced into the numerical procedure. Its results agree quanititatively with previously published experimental data showing a significant effect of lift‐induced particle transport. Based on the numerical results algebraic correlations are obtained, which enable to calculate the particle deposition rate in situations where lift forces and mobility reduction diminishes the particle deposition rate.
Thermal resistance of steam‐generator tube deposits under single‐phase forced convection and flow‐boiling heat transfer
Authors: Turner Carl W. , Klimas Stan J. , Brideau Mike G.
Published: March 2009

Measurements were made of the thermal resistance of porous deposits of various thicknesses under both single‐phase forced convection and flow‐boiling conditions. Both synthetic deposits and deposits on tubes removed from operating steam generators were used in this investigation. The thermal resistance was modeled as the sum of two components: one associated with conduction through the porous deposit and a second associated with the effect of surface roughness. The conductive component of the thermal resistance was always positive, whereas surface roughness made a negative contribution to the thermal resistance, i.e., roughness enhanced the rate of heat transfer. Thermal conductivity of the porous deposits was higher for single‐phase forced convection, whereas the effect of deposit roughness on thermal resistance was higher under flow‐boiling conditions. The results are discussed in terms of the effect of composition, morphology, surface roughness, and the mode of heat transfer on the thermal resistance of porous deposit.
Kinetic modelling of oxygen dependence in oxidative dehydrogenation of propane
Authors: Creaser Derek C. , Hudgins Robert R. , Silveston Peter L. , Andersson Bengt
Published: March 2009

Several Mars—Van Krevelen‐type redox kinetic models were developed for the catalytic oxidative dehydrogenation of propane and examined for their ability to predict high propene yields at low oxygen/propane feed ratios. The intent in this study was to use modelling as a means of extracting further mechanistic insight from experimental data rather than to identify the best model. Thus, a conventional redox model with a consecutive reaction mechanism and a single pathway for the production of carbon oxides predicts higher propene selectivity but only at the expense of low propane conversion. Experimental data indicated, however, that even at the same propane conversion, propene selectivity increased as the oxygen partial pressure was lowered. Models that successfully describe the data had an additional carbon oxide production path involving the reaction of propane with deeply oxidizing surface oxygen species. Kinetic models and experimental data examined do not fully resolve how these deeply oxidizing surface oxygen species are formed. However, they do reflect the accepted view that lattice oxygen selectively produces propene whereas more weakly bound surface adsorbed oxygen reacts to completely oxidize propane.
Degradation of solvolysis lignin using Lewis acid catalysts
Authors: Hepditch Mona M. , Thring Ronald W.
Published: March 2009

Alcell‐derived lignin was depolymerized in a batch reactor using the Lewis acid catalysts NiCl2 and FeCl3. The objective was to investigate the use of Lewis acids in the production of useful liquid products directly from solvolysis lignin. The effects of reaction temperature, time and catalyst were studied on the conversion of this lignin to gas, solid and liquid products. Also, selected monomeric compounds in the ether solubles were monitored in terms of the variation in their yields with different reaction conditions. The highest conversions, 30% and 26% from Ni and Fe, respectively, were both attained at the reaction conditions of 305°C and 1 h reaction time. The Ni produced a somewhat higher yield of ether solubles, reflecting its slightly higher performance. Under the reaction conditions studied, both catalysts apparently favour condensation reactions leading to the formation of insoluble reactor residue from solvolysis lignin. Low quantities of monomeric compounds were produced, with phenols dominating over ketones and aldehydes for both catalysts.
New image analysis methods for the study of mixing patterns in stirred tanks
Authors: Guillard Fabrice , Trägårdh Christian , Fuchs Laszlo
Published: March 2009

A method of treating data acquired with the planar laser‐induced fluorescence technique has been developed to visualize the topology of two‐dimensional concentration fields and to describe the dynamics of the coherent mixing structures identified. This method is based on a conditional binary transformation of the local concentration data, combined with a joint probability calculation. The methodology has been used to investigate the mixing in a stirred tank, at two injection port locations (in the bulk and in the impeller stream region). With bulk injection, a “folding phenomenon” of the coherent mixing structure was detected. Away from this port, large‐scale spatially periodic motion was identified, with a characteristic time of oscillation of the order of 2 to 3 s. With injection in the impeller stream region, no spatial instabilities of the coherent structure were detected. Local oscillations of the coherent mixing structure were found both on short and long time‐scales (i.e., ˜1 and ˜80 s).
Gas hold‐up in bubble columns: Operation with concentrated slurries versus high viscosity liquid
Authors: Krishna Rajamani , Urseanu Maria I. , De Swart Jeroen W. A. , Ellenberger Jürg
Published: March 2009

The hydrodynamics of bubble columns with concentrated slurries of paraffin oil (density, ρL = 790 kg/m3; viscosity, μL = 0.0029 Pa·s; surface tension, σ = 0.028 N·m1) containing silica particles (mean particle diameter dp = 38 μm) has been studied in columns of three different diameters, 0.1, 0.19 and 0.38 m. With increasing particle concentration, the total gas hold‐up decreases significantly. This decrease is primarily caused by the destruction of the small bubble population. The hold‐up of large bubbles is practically independent of the slurry concentration. The measured gas hold‐up with the 36% v paraffin oil slurry shows remarkable agreement with the corresponding data obtained with Tellus oil (ρL = 862 kg/m3; μL = 0.075 Pa·s; σ = 0.028 N·m−1) as the liquid phase. Dynamic gas disengagement experiments confirm that the gas dispersion in Tellus oil also consists predominantly of large bubbles. The large bubble hold‐up is found to decrease significantly with increasing column diameter. A model is developed for estimation of the large bubble gas hold‐up by introduction of an wake‐acceleration factor into the Davies‐Taylor‐Collins relation (Collins, 1967), describing the influence of the column diameter on the rise velocity of an isolated spherical cap bubble.
A new model for the propagation of jets in dilute gas‐solid crossflows
Authors: Indenbirken Matthias , Schneider Torsten , Siepmann Volker , Strauss Karl
Published: March 2009

The three‐dimensional propagation of a horizontal gas jet injected into a gas‐solid crossflow is described by a model based on the mass and momentum balances for both phases. The potential core close to the nozzle, the kidney‐shaped cross‐section of the jet and the region of rapidly increasing jet volume are taken into account. Viscous and turbulent stresses within the gas phase as well as the momentum exchange with the solid phase are considered. Several parameters are determined empirically by experimental data obtained by measurements in a dilute circulating fluidized bed. The comparison of calculated with experimental data shows good agreement concerning the shape of the jet axis and the solid phase concentration.
A rate—controlling step in langmuir—hinshelwood kinetic models
Authors: Belohlav Zdenek , Zamostny Petr
Published: March 2009

Langmuir‐Hinshelwood models with and without rate controlling step assumptions have been compared. Hydrogenations of toluene, cinnamaldehyde and mixture of methylesters of fatty acids were used as model systems. Integral data were obtained in semibatch reactors. The proposed models have been simplified by neglecting statistically insignificant parameters. The predicted mixture composition and surface coverages have been compared and the reliability of parameter estimates tested.
Heat and mass transfer in granular potash fertilizer with a surface dissolution reaction
Authors: Pen Shi‐Wen , Besant Robert W. , Strathdee Graeme
Published: March 2009

Potash is a widely used granular fertilizer and when exposed to high humidities it readily adsorbs water vapour forming a liquid electrolyte solution on each particle. Heat and mass transfer due to air flow through granular potash beds is studied experimentally and numerically. A one dimensional experimental setup is used to measure the temperature and air humidity response and mass gain of a potash bed subjected to a change in air flow. A porous media mathematical model is developed to predict the transient temperature and moisture content distributions. The processes are modelled as nonequilibrium heat and mass transfers between the porous solid and air flow gaseous phases. The state of the surface electrolyte solution is modelled by the thermodynamics of electrolyte solutions. Experimental and numerical results show non‐equilibrium internal moisture and heat transfer processes exist with significant differences in the pore air and particle temperature and surface relative humidity.
High temperature desulphurization by fine limestone during staged fluidized‐bed combustion
Authors: Khan Wasi Z. , Gibbs Bernard M.
Published: March 2009

This paper reviews the SO2 emission from a 0.3 m2 stainless‐steel fluidized‐bed combustor. Fine coal was premixed with fine limestone and fed pneumatically under the bed. The SO2 emission was found to depend largely on air staging ratio and bed temperature, which agrees with previous observations. The SO2 emission observed in sorbent‐free tests (reported earlier by Khan and Cibbs, 1995) was found to be proportional to the sulphur content of the fuel when limestone was added, the sulphur capture at a fixed Ca/S molar ratio was dependent on oxygen stoichiometry and bed temperature. Finely sized limestone enhanced the effectivity of the sorbent at low bed temperature and air staging ratio. During staged combustion, the combustion efficiency depended largely on primary air to coal ratio. Around 90% combustion efficiency was observed at 1 m/s fluidizing velocity which was reduced when fluidizing velocity was increased to 1.5 and 2 m/s. This reduction is due to increased elutriation of finer coal particles from the combustor.
A fluidized bed kinetic model for the fluorination of dissociated zircon
Authors: Moolman Francis Sean , Heydenrych Michael David
Published: March 2009

A reaction kinetic model for the fluorination of plasma dissociated zircon (PDZ, or ZrO2.SiO2) with hydrogen fluoride was developed. The model uses reaction as rate‐limiting step, with a shrinking core of PDZ in a porous matrix of zirconia (ZrO2). This model was used to develop models for a multi‐stage fluidized bed reactor. These models facilitated the determination and design of an optimally configured multi‐stage fluidized bed reactor for the fluorination of PDZ. It was shown that a combination cross‐/countercurrent multi‐stage fluidized bed reactor could yield significant improvement over the conventional countercur‐rent multi‐stage fluidized bed reactor for certain reaction kinetic conditions.
Application of apdc coupled polyurethane foam sorbent for the removal and recovery of toxic heavy metals Hg, Cd and Pb from industrial effluents
Authors: Anjaneyulu Yerramilli , Rao Rachakulla Venkata Sambasiva
Published: March 2009

A novel, highly stable, selective and efficient sorption medium was synthesized for the removal of toxic metals from industrial effluents by coupling a chelating agent Ammonium pyrrolidine dithiocarbamate (APDC) with flexible open cell polyether polyurethane foam. The performance efficiency of the new sorbent was evaluated by static and dynamic methods for removing toxic heavy metals Hg, Cd and Pb from effluents. In fixed bed downflow column studies, a quantitative uptake of Hg (II) 400 mg/L, Cd (II) and Pb (II) 60 mg/L was attained at flow rates of 3.68 L/m2s. The design parameters using the APDC‐PUF as sorption material for a batch reactor and for column reactor and cost effectiveness of the process were evaluated. The sorption potential of the APDC‐PUF was demonstrated for the treatment of real industrial wastes from a common effluent treatment plant, Chloro alkali industry and municipal sewage.
Comparison of experimental results and numerical predictions of drop diameter from a single submerged nozzle in a liquid‐liquid system
Authors: Hamad Faik A. , Khan Mohammed K. , Pierscionek Barbara K. , Bruun Hans H.
Published: March 2009

This paper presents a comparison of experimental results and numerical predictions of drop formation from a single submerged nozzle for a liquid‐liquid system. The theoretical model is a modification of previous models used for a two‐stage drop formation mechanism. The model has been tested against experimental data for kerosene drop formation in distilled water using a range of different nozzle diameters. In addition, our liquid‐liquid model has been compared with both experimental and predicted results from published literature. These comparisons demonstrate that for liquid‐liquid systems, the present predictions of drop diameter versus dispersed phase nozzle velocity are in overall agreement with both the present and previous experimental results. In addition, the present model predictions are more accurate than those of previous models for liquid‐liquid systems.
Scale‐up of single phase axial dispersion coefficients in batch and continuous oscillatory baffled tubes
Authors: Ni Xiongwei , De Gélicourt Yann Sommer , Baird Malcolm H. I. , Rao Nadella V. Rama
Published: March 2009

This note presents the development of a scale‐up correlation of single‐phase axial dispersion coefficients in both batch and continuous oscillatory baffled flow systems. A hydraulic diameter is introduced to relate axial dispersion coefficients for various baffle geometry, including close‐fit and loose‐fit baffles, Karr plate and multiperforated plate, and various scales. The significance of this note is that the mixing characteristic in oscillatory flow devices is linear.
A feasibility study of adaptive plasma‐assisted incineration, Part 2: Techno‐Economic potential assessment
Authors: Filion Julie , Munz Richard J. , Salin Eric D.
Published: March 2009

This work assesses the techno‐economic potential of using an adaptive d.c. thermal plasma afterburner in hazardous waste incineration. Preliminary cost estimates were developed for soil incineration, soil desorption and liquid waste incineration. In general, the annual operating costs of plasma‐assisted processes (including depreciation of capital) exceed the costs of fuel combustion processes by 50%. However, a qualitative examination of environmental, legal and technical factors suggests that plasma treatment offers significant benefits in terms of effectiveness, safety and regulatory compliance.
Complex integration of processes
Authors: Glavič Peter
Published: March 2009

Pinch analysis is nowadays a practical tool for designing heat exchanger networks in chemical and process industries. Rules for integrating process units have also been worked out in the last decade or two. Process units can be described as different types of energy unit operations, donors and acceptors. Yet, heat integration alone is not sufficient for process integration. The largest savings are achieved when simultaneously optimizing enthalpy and mass flows — energy and material recycling is required to save the natural resources and protect the nature. Mathematical programming is increasingly used to optimize the problems both in continuous and batch operations. Task integration is spreading out: multifunctional units lower the capital investment, thus, the total annual cost Recent development of the complex integration with examples and reasonable forecast of the future development is presented in the paper.
Simultaneous isolation of keratinocytes and fibroblasts from a human cutaneous biopsy for the production of autologous reconstructed skin
Authors: Rochon Marie‐Hélène , Gauthier Marie‐Josée , Auger Francois A. , Germain Lucie
Published: March 2009

The key step In the reconstruction of skin by the self‐assembly approach is to use fibroblasts capable of secreting a mature extracellular matrix and keratinocytes that can associate with one another to form a stratified, differentiated epidermis. To determine the most efficient way to extract both cell types from a single cutaneous biopsy, five different enzymatic combinations were tested. The yield, viability and morphology of the recuperated cells were compared. The length and temperature of the enzymatic treatments influenced the number and the type of cells recuperated. The cells were then cultured in appropriate media in monolayers and reconstructed skin were produced using the self‐assembly approach. No difference was observed between the different strains of cells.
Survey of heat transfer mechanisms in a slurry bubble column
Authors: Li Hanning , Prakash Anand
Published: March 2009

Heat transfer mechanisms in the bulk and distributor regions of a slurry bubble column are investigated based on the measurements of local heat transfer in a 0.28 m diameter Plexiglas column. The gas, liquid and solid phases used are oil‐free compressed air, tap water and 35 μm glass beads. The slurry concentration and superficial gas velocity are varied from 0 to 40 vol% and 0.05 to 0.30 m/s respectively. Measurements have been made with a fast response heat flux probe which provided local instantaneous heat transfer coefficients. The time‐averaged heat transfer coefficients in the bulk region were on average about 50% higher than the distributor region of the column. The wall region heat transfer coefficients are well predicted by the correlation of Deckwer et al. (1980). Heat transfer mechanism in column centre can be adequately described by the consecutive film and surface renewal model.
Nucleophilic substitution sulfonation in emulsions: Formation of sodium benzyl sulfonate
Authors: Husein Maen M. , Weber Martin E. , Vera Juan H.
Published: March 2009

Benzyl bromide was sulfonated at 298 K in emulsions formed with dioctyldimethylammonium bromide, or chloride. If mixing was sufficient, the emulsion was maintained throughout the reaction period. Lower conversions were obtained whenever benzyl bromide phase separated from the mixture. Chloride as surfactant counterion gave higher reaction rate, but decreased the conversion to C7H7SO3−Na+due to formation of benzyl chloride. The conversion to C7H7SO3−Na+ displayed a broad maximum as R2(Me)2−N+Br concentration increased. Except at low concentration, the reaction rate increased with the concentration of Na2SO3 in accord with the SN2 mechanism. The reaction rate increased with the reactant concentrations until interface saturation was achieved, suggesting that product formation did not interfere with the access of the reactants to the interface.
A CFD assessment of film coating process viscosity models
Authors: Alonso Sergio , Bertrand Franqois , Tanguy Philippe A.
Published: March 2009

Computer fluid dynamic simulations of the metering nip flow were used to assess the process viscosity of the coating colours. The numerical solution was based on a Calerkin/finite element technique that included the deformation of the roll cover to better represent the flow elastohydrodynamics. The Navier‐Stokes prediction was compared with experimental measurements of torque and pressure in the metering nip. From the comparisons, the process viscosity determined in a region of shear‐dominated flow is the one, among the three models analyzed, that can better describe the hydrodynamics of the metering nip flow. To improve further the fluid flow numerical description, this process viscosity was combined with an adapted transient Cross model. This new semianalytical rheological model decreased the differences between the numerical and experimental results. The findings also suggested that the model requires further enhancements, topic that will be addressed in future work.
Structure and Function of Benzoylurea‐Derived α‐Helix Mimetics Targeting the Bcl‐xL/Bak Binding Interface
Authors: Rodriguez Johanna M. , Ross Nathan T. , Katt William P. , Dhar Deepali , Lee Gui‐in , Hamilton Andrew D.
Published: March 2009

Targeting Bcl‐xL/Bak: A family of rationally designed α‐helix mimetics with improved solubility and synthetic feasibility based on a benzoylurea scaffold is presented. These benzoylurea derivatives favor a linear conformation stabilized by an intramolecular hydrogen bond, and are able to mimic the spatial projection of the i, i+4, and i+7 residues of an α‐helix. Binding affinities of the benzoylurea derivatives to Bcl‐xL have been assessed using fluorescence polarization competition assays and isothermal titration calorimetry.

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The Bcl‐xL/Bak protein–protein interaction has emerged as an important target for cancer therapy due to its role in apoptosis. Inhibition of this interaction by small‐molecule antagonists induces apoptosis in unhealthy cells. Bak, a pro‐apoptotic Bcl‐2 protein, projects four hydrophobic side chains (V74, L78, I81, and I85), corresponding to the i, i+4, i+7, and i+11 positions of an α‐helix, into a hydrophobic cleft on Bcl‐xL. Herein, we present a novel family of rationally designed α‐helix mimetics with improved solubility and synthetic feasibility based on a benzoylurea scaffold. These benzoylurea derivatives favor a linear conformation stabilized by an intramolecular hydrogen bond, and are able to mimic the spatial projection of the i, i+4, and i+7 residues of an α‐helix. The binding of the benzoylurea derivatives to Bcl‐xL was assessed using fluorescence polarization competition assays, isothermal titration calorimetry, and 15N‐HSQC experiments. These experiments showed that these agents bind to and disrupt Bcl‐xL with low micromolar inhibition and dissociation constants, with 15N‐HSQC experiments confirming binding to the hydrophobic pocket of Bcl‐xL normally occupied by the Bak helix.
Ru‐Based Olefin Metathesis Catalysts Bearing pH‐Responsive N‐Heterocyclic Carbene (NHC) Ligands: Activity Control via Degree of Protonation
Authors: Balof Shawna L. , Yu Bing , Lowe Andrew B. , Ling Yan , Zhang Yong , Schanz Hans‐Jörg
Published: March 2009

Olefin metathesis catalysts (H2ITap)(PCy3)Cl2Ru=CHPh (4) and (H2ITap)Cl2Ru=CH‐(C6H4‐O‐iPr) (5) [H2ITap = 1,3‐bis(2′,6′‐dimethyl‐4′‐dimethylaminophenyl)‐4,5‐dihydroimidazol‐2‐ylidene] were used for the ring‐opening metathesis polymerization (ROMP) of exo‐7‐oxanorbornene derivative 7 in the presence of various amounts of acid. Upon gradual protonation of the NMe2 groups of the H2Tap ligand, the metathesis activity of both catalysts were gradually reduced due to electronic changes of the N‐heterocyclic carbene (NHC) ligand donor capability. The investigation of the ROMP polymer 8, DFT calculations and measurements of the initiation kinetics prove that the reduced activity is solely due to reduced rates of propagation.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Clonazepam as a therapeutic adjunct to improve the management of depression: a brief review
Authors: Morishita Shigeru
Published: March 2009

Clonazepam, first used for seizure disorders, is now increasingly used to treat affective disorders. We summarize the use of clonazepam to improve the management of depression. Clonazepam is useful for treatment‐resistant and/or protracted depression, as well as for acceleration of response to conventional antidepressants. Clonazepam is at this time recommended for use in combination with SSRIs (fluoxetine, fluvoxamine, sertraline) as an antidepressant, and should be used at a dosage of 2.5–6.0 mg/day. If clonazepam is effective, a response should be observed within 2–4 weeks. It is significantly more effective for unipolar than for bipolar depression. Low‐dose, long‐term treatment with clonazepam exhibits a prophylactic effect against recurrence of depression. Although the mechanism of action of clonazepam has not yet been established, some investigators have been suggested that it involves enhancement of anti‐anxiety effects, anticonvulsant effects on subclinical epilepsy, increase in 5‐HT/monoamine synthesis or decrease in 5‐HT receptor sensitivity mediated through the GABA system, and regulate in GABA activity. Copyright © 2009 John Wiley & Sons, Ltd.
Selection of highly osteogenic and chondrogenic cells from bone marrow stromal cells in biocompatible polymer‐coated plates
Authors: Liu G. , Iwata K. , Ogasawara T. , Watanabe J. , Fukazawa K. , Ishihara K. , Asawa Y. , Fujihara Y. , Chung U.‐L. , Moro T. , Takatori Y. , Takato T. , Nakamura K. , Kawaguchi H. , Hoshi K.
Published: March 2009

To enrich the subpopulation that preserves self‐renewal and multipotentiality from conventionally prepared bone marrow stromal cells (MSCs), we attempted to use 2‐methacryloyloxyethyl phosphorylcholine (MPC) polymer‐coated plates that selected the MSCs with strong adhesion ability and evaluated the proliferation ability or osteogenic/chondrogenic potential of the MPC polymer‐selected MSCs. The number of MSCs that were attached to the MPC polymer‐coated plates decreased with an increase in the density of MPC unit (0–10%), whereas no significant difference in the proliferation ability was seen among these cells. The surface epitopes of CD29, CD44, CD105, and CD166, and not CD34 or CD45, were detectable in the cells of all MPC polymer‐coated plates, implying that they belong to the MSC category. In the osteogenic and chondrogenic induction, the MSCs selected by the 2–5% MPC unit composition showed higher expression levels of osteoblastic and chondrocytic markers (COL1A1/ALP, or COL2A1/COL10A1/Sox9) at passage 2, compared with those of 0–1% or even 10% MPC unit composition, while the enhanced effects continued by passage 5. The selection based on the adequate cell adhesiveness by the MPC polymer‐coated plates could improve the osteogenic and chondrogenic potential of MSCs, which would provide cell sources that can be used to treat the more severe and various bone/cartilage diseases. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res 2010
Inactivation of uPA and its receptor uPAR by 3,3′‐diindolylmethane (DIM) leads to the inhibition of prostate cancer cell growth and migration
Authors: Ahmad Aamir , Kong Dejuan , Sarkar Sanila H. , Wang Zhiwei , Banerjee Sanjeev , Sarkar Fazlul H.
Published: March 2009

3,3′‐Diindolylmethane (DIM) has been studied for its putative anti‐cancer properties, especially against prostate cancer; however, its exact mechanism of action remains unclear. We recently provided preliminary data suggesting down‐regulation of uPA during B‐DIM (a clinically active DIM)‐induced inhibition of invasion and angiogenesis in prostate cancer cells. Since the expression and activation of uPA plays important role in tumorigenicity, and high endogenous levels of uPA and uPAR are found in advanced metastatic cancers, we investigated their role in B‐DIM‐mediated inhibition of prostate cancer cell growth and motility. Using PC3 cells, we found that B‐DIM treatment as well as the silencing of uPA and uPAR by siRNAs led to the inhibition of cell growth and motility. Conversely, over‐expression of uPA/uPAR in LNCaP and C4‐2B cells resulted in increased cell growth and motility, which was effectively inhibited by B‐DIM. Moreover, we found that uPA as well as uPAR induced the production of VEGF and MMP‐9, and that the down‐regulation of uPA/uPAR by siRNAs or B‐DIM treatment resulted in the inhibition of VEGF and MMP‐9 secretion which could be responsible for the observed inhibition of cell migration. Interestingly, silencing of uPA/uPAR led to decreased sensitivity to B‐DIM indicating important role of uPA/uPAR in B‐DIM‐mediated regulation of prostate cancer cell growth and migration. Our data suggest that chemopreventive and/or therapeutic activity of B‐DIM is in part due to down‐regulation of uPA–uPAR leading to reduced production of VEGF/MMP‐9 which ultimately leads to the inhibition of cell growth and migration of aggressive prostate cancer cells. J. Cell. Biochem. 107: 516–527, 2009. © 2009 Wiley‐Liss, Inc.
Social outsourcing as a development tool: The impact of outsourcing IT services to women's social enterprises in Kerala
Authors: Heeks Richard , Arun Shoba
Published: March 2009

Social outsourcing means the contracting out of goods or services to social enterprises. When used by government, it can be seen as a hybrid of the workfare outsourcing found in wage employment schemes, and the commercial outsourcing of government activities to the private sector. This paper focuses on a social outsourcing initiative operated by the government of Kerala State, India. Part of this outsources information technology (IT) services to dozens of cooperatives of women from below‐poverty‐line families. Interview and case study research was undertaken to assess the impacts of this initiative on five areas of livelihood assets—financial, human, physical, social and political capital. This scheme has Keralan specificities and research shows that social outsourcing may introduce vulnerabilities and questions of sustainability. Overall, though, this paper suggests that social outsourcing has the potential to deliver developmental benefits to marginalised groups. It is therefore worthy of greater attention from international development agencies and governments in developing countries. Copyright © 2009 John Wiley & Sons, Ltd.
Myelin under stress
Authors: D'Antonio Maurizio , Feltri M. Laura , Wrabetz Lawrence
Published: March 2009

The capacity to fold proteins properly is fundamental for cell survival. Secreted and transmembrane proteins are synthesized in the endoplasmic reticulum (ER), an organelle that has the ability to discriminate between native and nonnative proteins, in a process called protein quality control. When folding is not properly achieved, misfolded proteins can accumulate. The terminally misfolded proteins are typically retrotranslocated into the cytoplasm for degradation by the proteasome, in a process known as endoplasmic reticulum‐associated degradation. However, if the degradation is insufficient, accumulation of abnormal proteins in the ER activates the unfolded protein response (UPR), a complex set of new signals aimed to reduce further the load of abnormal protein in the ER. Massive synthesis of myelin lipids and proteins is necessary to support myelinogenesis. Not surprisingly, therefore, ER stress (including the UPR), the proteasome, and autophagy (lysosomes) have been implicated in myelin disorders, such as Pelizaeus‐Merzbacher disease and vanishing white matter disease in the central nervous system and Charcot‐Marie‐Tooth neuropathies in the peripheral nervous system. Here we discuss recent evidence supporting an important role for ER stress in myelin disorders. © 2009 Wiley‐Liss, Inc.
Wind speed measurements and forest damage in Canton Zurich (Central Europe) from 1891 to winter 2007
Authors: Usbeck Tilo , Wohlgemuth Thomas , Pfister Christian , Volz Richard , Beniston Martin , Dobbertin Matthias
Published: March 2009

The most severe damage to forests in central Europe occurs during winter storms that are caused by Northern Hemispheric mid‐latitude cyclones. These winter storms have caused several catastrophic windthrows during the past four decades. Amounts of forest storm damage are believed to be a function of both the size of the forest and the storm intensity. To test this hypothesis, the Zurich region (city and canton) was chosen because long‐term climate observation data is available for the region. The relationships between forest attributes, wind speed and forest damage were explored by comparing data on forests and wind speed from 107 winters with forest damage. Storm damage was defined as the proportion of damaged forests with respect to the growing stock. The variables: daily wind run (91 years), daily maximum hourly average wind speed (107 years) and peak gust wind speed (74 years) were homogenized with respect to high wind speed and related to levels of forest damage.

High maximum wind speed at the end of the 19th century and at the beginning of the 20th century was followed by low maximum wind speed in the 1940s, 1960s and 1970s. Since then, maximum values have increased. Gusts (extremes of the maximum wind speed) increased from the beginning of the recordings in 1933 and peaked in the early 1990s.

Forest damage due to winter storms is best correlated with peak wind speed. Gusts exceeding 40 m/s and resulting in catastrophic windthrow have increased in recent winters. Copyright © 2009 Royal Meteorological Society