bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of the allylation of phenoxide by polyethylene glycol in a two‐phase reaction
Authors: Wang Maw‐Ling , Chang Kong‐Rong
Published: March 2009

Polyethylene glycol (PEG) was used as the phase transfer catalyst in the two‐phase allylation of phenoxide with allyl chloride. The kinetics of the reaction both in the organic phase and in the aqueous phase was studied in detail based on the ion‐extraction mechanism. The reaction rates both in the organic and aqueous phases were increased by PEG. The concentration of phenoxide in the organic phase results from adding PEG followed by a reaction second order in the concentration of phenoxide in the aqueous phase. This is due to the ability of PEGs to form complexes with sodium cations. In the aqueous phase, the PEG will enhance the solubility of allyl chloride.
Effect of solid particles on gas hold‐up in bubble columns
Authors: Jamialahmadi M. , Müller‐Steinhagen H.
Published: March 2009

The gas hold‐up in bubble columns containing fluidised plastic particles as solid phase was measured as a function of superficial gas velocity and solids concentration. The effects of particle size, density, wettability and concentration on gas hold‐up and bubble coalescence were studied. It was found that the addition of non‐wettable solids to the air/water mixture promotes bubble coalescence and, therefore, reduces the gas hold‐up, while the addition of wettable solids suppresses bubble coalescence and increases the gas hold‐up.
Hydrodynamics in rectangular air‐lift reactors: Scale‐up and the scale‐up and the influence of gas‐liquid separator design
Authors: Siegel Marc , Merchuk Jose C.
Published: March 2009

Experiments were conducted on air‐lift reactors with different liquid volumes, aspect ratios, and gas‐liquid separator configurations, with constant downcomer to riser cross‐sectional area ratio and riser/downcomer height. Reactor performance was highly dependent on the gas‐liquid separator design. By changing the latter, the mode of operation could be changed from that of a concentric tube reactor (with gas recirculation) to an external loop reactor (without gas recirculation). Liquid velocity and overall gas hold‐up data were correlated to the power per liquid volume and “Disengagement Ratio”, a geometric parameter describing the separator's configuration. During scale‐up, similar gas hold‐ups and liquid velocities were found in laboratory and pilot reactors. A modified air‐lift reactor with an enlarged channel for a gas‐liquid separator also was studied.
Carrier influence in anaerobic biofilm fluidized beds for treating vapour condensate from the sulphite cellulose process
Authors: Petrozzi S. , Dunn I. J. , Heinzle E. , Kut O. M.
Published: March 2009

The continuous anaerobic degradation of an acidic waste water from a cellulose process was investigated in six fluidized bed reactors. Various materials including limestone, porous glass, quartz sand, activated carbon and treated coal were used as support particles. The reactors were operated for several months with vapour condensate from a sulphite cellulose process as feed. The performance and stability of the reactors with respect to degradation rate were tested for a range of loading conditions. Unbuffered, buffered and pH‐controlled conditions were compared. The results showed that the high‐density, small‐sized sand was the best carrier. Carrier porosity was not important, although surface roughness appeared to be important. No clear evidence of diffusional influence on the kinetics was observed. The highest rates and best stability was obtained with the sand carrier which had the thinnest biofilm; these rates were 21 kg COD/m3. d(unbuffered feed), or 25 kg COD/m3. d (buffered feed and pH‐controlled system). The sand system was relatively stable with respect to pH changes. With pH control, loading could be increased until a maximum reaction rate, as determined by the saturation kinetics, was achieved.
Electrochemical kinetic parameters for the cathodic deposition of copper from dilute aqueous acid sulfate solutions
Authors: Hinatsu J. T. , Foulkes F. R.
Published: March 2009

The use of linear‐sweep voltammetry and chronopotentiometry for the determination of kinetic parameters for the electrolytic recovery of copper from a simulated acid‐copper electroplating waste solution was demonstrated. For the electrodeposition of copper from solutions of 0.007˜0.008 mol/L CuSO4 + 0.5 mol/L H2SO4 at 25°, the recommended values of the transfer coefficient (α) and exchange current density (i0) are α = 0.46±0.06 (95% confidence interval) and i0 = 11±4 A/m2. The close agreement between these values and the available literature values indicates the reliabilaity of the voltammetric and chronopotentiometric methods.
Morphological influences in the gas phase polymerization of ethylene by silica supported chromium oxide catalysts
Authors: Webb Steven W. , Weist E. L. , Chiovetta M. G. , Laurence R. L. , Conner W. C.
Published: March 2009

Dramatic changes occur during the initial stages of olefin polymerization over heterogenous catalysts. As polymer accumulates, the catalyst fragments and the void space within the growing particle becomes filled with polymer. The changing monomer transport rate to the active sites, dissipation of heat and stress with the particle, and eventually, dispersion of catalyst fragments within the growing particle can control the polymerization. We focus on the changes in, and influence of, polymer, catalyst and void morphology during the nascent polymerization for silica supported chromium oxide catalysts. We find that the course of the polymerization depends on the initial stages yet is seldom considered in polymerization models. We review several years of morphological characterization that identify the important physical phenomena which occur during nascent heterogeneous olefin polymerization.
Modéalisation de la copolyméarisation éathylégne α‐oléafine par catalyse ziegler—natta
Authors: Lorenzini Pascal , Bertrand Pascale , Villermaux Jacques
Published: March 2009

On présente un modèle de copolymérisation de l'éthylène et d'une α‐oléfine qui décrit la consommation des monomères et la qualité du polymère produit, á savoir Mn, Mw, Mz, la distribution des masses moléculaires, les indices de branchement court et de doubles liaisons. Le modèle suppose qu'il existe plusieurs types de sites actifs (2 ou 3) et ne fait pas intervenir de limitation diffusionnelle. On l'applique á la copolymérisation en masse de l'éthylène et du butène‐1 sous haute pression et haute température. Les paramètres sont identifiés grǎce á des essais en réacteur agité continu.
A numerical solution of the wavy motion on a falling liquid film
Authors: Yang Ru , Wood Byard D.
Published: March 2009

Wavy motion in falling liquid films enhances heat and mass transfer significantly; therefore, it is important to successfully model this motion for the purpose of heat and mass transfer calculations. In this study, a simple and promising numerical spectral method is developed to solve the periodic wavy film flow equations. With the wave number and the wave celerity specified to be those of the most unstable waves from existing linear stability analysis, the results are found to be good when compared with the existing experimental data for small (Re < 50) and moderate (50 < Re < 150) Reynolds numbers. It is worth noting that many important absorption problems fall in the low and moderate Reynolds number regimes. For higher Reynolds number flows (Re > 150), the solutions are still obtainable but may not be realistic owing to the invalidity of the linear stability analysis and the asymptotic wavy‐state assumption in the high Reynolds number flow.
Isobaric vapor liquid equilibrium in binary mixtures of α‐pinene, limonene and 1, 8‐cineole
Authors: Farelo Fátima , And Filomena Santos , Serrano Lurdes
Published: March 2009

Isobaric vapor liquid equilibrium at atmospheric pressure has been determined for binary mixtures of (–) α‐pinene, (+)‐limonene and 1, 8‐cineole. The Margules and Var Laar equations as well as the models proposed by Wilson, by Renon and Prausnitz (NRTL) and by Abrams and Prausnitz (UNIQUAC) were used to correlate the experimental data. The corresponding parameters for two binaries are reported here.
Oxidative coupling of methane in a bubbling fluidized bed reactor
Authors: Andorf R. , Mleczko L. , Schweer D. , Baerns M.
Published: March 2009

The oxidative coupling of methane to higher hydrocarbons (C2+) was studied in a bubbling fluidized bed reactor between 700°C and 820°C, and with partial pressures of methane from 40 to 70 kPa and of oxygen from 2 to 20 kPa; the total pressure was ca 100 kPa. CaO, Na2CO3/CaO and PbO/γ‐Al2O3were used as catalytic materials. C2+selectivity depends markedly on temperature and oxygen partial pressure. The optimum temperature for maximizing C2+selectivity varies between 720 and 800°C depending on the catalyst. Maximum C2+selectivities were achieved at low oxygen and high methane partial pressures and amounted to 46% for CaO (T = 780°C; PCH4= 70 kPa; PO2= 5 kPa), 53% for Na2CO3/CaO (T = 760°C; PCH4= 60 kPa; PO2= 6 kPa) and 70% for PbO/γ‐Al2O3(T = 720°C; PCH4= 60 kPa; PO2= 5 kPa). Maximum yields were obtained at low methane‐to‐oxygen ratios; they amounted to 4.5% for CaO (T = 800°C; PCH4= 70 kPa; PO2= 12 kPa), 8.8% for Na2CO3/CaO (T = 820°C; PCH4= 60 kPa; PO2= 20 kPa) and 11.3% for PbO/γ‐Al2O3(T 2= 800°C; PCH4= 60 kPa; PO2= 20 kPa).
On‐line multivariable adaptive control of a binary distillation column
Authors: Tham M. T. , Vagi F. , Morris A. J. , Wood R. K.
Published: March 2009

An experimental evaluation of the simultaneous control of top and bottom product compositions of a binary distillation column utilizing multi‐variable self‐tuning control algorithms is presented. The study was carried out using an 8‐tray, 22.86 cm diameter methanol–water pilot scale column with continuous capacitance analysis of top product composition and bottom composition analyzed on a 3 minute cycle, by a gas chromatograph. Column control is studied for ±25% step disturbances in feed flow rate. Terminal composition regulation using both ‘positional’ and ‘incremental’ forms of a generalized minimum variance self‐tuning control algorithm is compared with that achieved using a conventional digital PI/PID multiloop control strategy.
Catalytic upgrading of biomass‐derived oils to transportation fuels and chemicals
Authors: Sharma R. K. , Bakhshi N. N.
Published: March 2009

This paper provides a review of the catalytic upgrading of biomass‐derived oils such as wood pyrolytic oils, plant/vegetable oils and tall oil to transportation fuels and useful chemicals. Both zeolite and hydrotreating type catalysts have been found suitable for upgrading which was usually done in fixed bed reactors. The hydrotreatment of pyrolytic oils at 250‐450°C and 15‐20 MPa H2 pressures has been reported to yield up to 55 wt. % of liquid product containing 40‐50 wt. % of gasoline range hydrocarbons. In the case of HZSM‐5, the upgrading has been carried out at atmospheric pressure and 350‐500°C and over 85 wt. % conversions of plant oils and tall oil have been achieved under optimum conditions. Liquid product yields from these oils were up to 70 wt. % of feed which contained 40‐50 wt. % aromatic hydrocarbons. With the high pressure pyrolytic oil, pitch conversions of over 75 wt. % have been observed with HZSM‐5 using co‐feeds such as tetralin. However, there is only scant information available on the kinetic and mechanistic aspects of upgrading of these oils.
Catalytic oxidation of carbon monoxide under periodic operation
Authors: Silveston P. L.
Published: March 2009

A growing literature demonstrates resonance of the rate of CO oxidation with frequency of composition switching and that a global increase in rate under composition modulation is possible. Differences are found for the various metal catalysts used: CO oxidation is stimulated at frequencies between 0.1 and 1.0 Hz over noble metals, whereas stimulation occurs at frequencies below 0.05 Hz with oxide catalysts. Multiple resonances with an apparent harmonic relationship, “wrong‐way” response, or very slow relaxation to reproducible cycles have been observed. These differences suggest mechanisms through which rate improvements arise are not the same for all catalysts.
Modified shape factors for improved viscosity predictions using corresponding states
Authors: Monnery Wayne D. , Mehrotra Anil K. , Svrcek William Y.
Published: March 2009

A new approach for evaluating the shape factors in the Extended Corresponding States Method is presented for improving the viscosity predictions of pure liquid hydrocarbons. Of the two shape factors in the method, the size shape factor ϕ is shown to be unnecessary. The energy shape factor θ is shown to correlate with the reduced temperature. Next, the correlation parameters are generalized for each family of hydrocarbon compounds. A further simplification in the viscosity calculation is accomplished by use of propane as the reference fluid whose density is calculated from the COSTALD method. The predicted viscosities of 46 pure liquid hydrocarbons are well within 6% of the data, and an order of magnitude better than those from available methods.
Computation and optical interferometric determination of concentration profiles near a vertical cathode
Authors: Nagatsugawa I. , Piron D. L. , Bures J.
Published: March 2009

Concentration profiles near a copper cathode immersed in a 0.3 mol/L CuSO4 aqueous solution were determined by theoretical computation and by measurement with a Jamin optical interferometer. The semi‐infinite diffusion and convective diffusion equations corrected by an experimental factor corresponded well with the experimental results.
The equilibrium phase properties of the propane‐methanol and n‐Butane‐methanol binary systems
Authors: Lev Ah‐Dong , Robinson Donald B. , Chung Samuels Y.‐K. , Chen C.‐J.
Published: March 2009

Vapor and liquid equilibrium phase compositions were determined at 310.7, 352.2, 393.0 and 474.3 K for the propane‐methanol system and at 469.9 K for the n‐butane–methanol system. Measurements were made at pressures from the vapor pressure of the less volatile component to the maximum pressure where two phases coexisted either as an azeo‐trope or at the critical condition, depending on the system. Azeotropic behavior was observed at 310.7 and 352.2 K for the propane‐methanol system. Equilibrium ratios were calculated at each temperature from the phase composition data. The temperature dependence of the azeotrope pressure and of the corresponding azeotrope composition was expressed analytically.
Hydrodynamic behaviour of a horizontal pulsed solvent extraction column. part 1: Flow characterization, throughput capacity and holdup
Authors: Melnyk A. J. , Vijayan S. , Woods D. R.
Published: March 2009

A horizontal pulsed solvent extraction column (HPC) has great potential in replacing vertical pulsed columns (VPC) in the separation of heavy elements in the nuclear industry. Published work examining the performance of the HPC suggests that the mass transfer efficiency for this column is comparable to the VPC, but information on the hydrodynamic characteristics of the HPC is sparse. This paper describes the flow characteristics of the HPC and presents experimental results and correlations for flooding conditions and holdup of the dispersed phase. Correlations obtained for the HPC for these hydrodynamic parameters are compared to published results for the VPC.
Hydrodynamics of spouted and spout‐fluidized beds at high temperature
Authors: Ye B. , Lim C. J. , Grace J. R.
Published: March 2009

Hydrodynamic parameters were investigated in a 0.15 m diameter half‐column spout‐fluidized bed at temperatures up to 880°C for ratios of auxiliary air flow to total air flow from 0 to 0.62 and four narrow size ranges of silica sand. Equations in the literature gave poor agreement with the minimum spouting velocity over the entire temperature range. For large particles Um generally increased with temperature, while for small particles it decreased. Auxiliary air had more influence at elevated temperatures than at room temperature. Pulsations leading to choking appeared to cause spout termination at elevated temperatures. The McNab and Bridgwater (1977) equation correctly predicted the observed trends for maximum spoutable bed depth at high temperatures.
Kinetics of the gas‐phase reaction between nitric oxide, ammonia and oxygen
Authors: Duo W. , Dam‐Johansen K. , Østergaard K.
Published: March 2009

For the purpose of developing a simple and quantitative description of the rate of reactions occurring in the Thermal DeNOx process, the kinetics of the homogeneous reaction between NO and NH3 with excess of O2 has been studied in an isothermal plug flow reactor.

Temperature windows of NO reduction were observed with the optimum temperature decreasing with increasing residence time. The degree of reduction of NO increases with residence time at lower temperatures but is sensitive to residence time only at very short residence times at higher temperatures. The degree of conversion of NH3 increases with both temperature and residence time.

A simple model has been proposed to describe the reaction rates:

rNO = kax [NH3] ‐ kr [NH3] [NO]

r =‐kax [NH3]‐ kr [NH3] [NO]

The two rate constants in the model were estimated based on the experimental data obtained in the present plug flow reactor at about 4% (vol.) oxygen:

kax = (2.21 ± 0.33) × 1014 exp [‐(38160 ± 170)/T], I/s

kr = (2.45 ± 0.49) × 1014 exp [‐(29400 ± 250)/T], m3mol. s

It is verified that the kinetic model can give a satisfactory prediction of the experimental results under different conditions.
Collection efficiencies and particle size distributions from sampling cyclones — comparison of recent theories with experimental data
Authors: Salcedo R. L.
Published: March 2009

The grade collection efficiencies and particle size distributions from Stairmand‐type cyclones are compared with predictions from four theories, viz. the models of Leith and Licht (1972), Dietz (1981) Mothes and Loffler (1988) and Li and Wang (1989). It is shown that the theory of Mothes and Loffler, which recogizes different flow regions within a cyclone, coupled with a realistic estimate of the particles turbulent diffusivity, is capable of providing good estimates of both the grade‐efficiency curves and particle size distributions of the cyclone catch and/or outlet dusts. The lack of adequate theories or empirical formulae to estimate the effective turbulent diffusivity under cyclone flow seems the major factor hindering the use of the Mothes and Loffler theory for predictive purposes. High loadings and agglomeration of fines, if present, are responsible for strong departures from theoretical predictions.
Kinetics of methane hydrate formation in aqueous electrolyte solutions
Authors: Dholabhai P.D. , Kalogerakis N. , Bishnoi P.R.
Published: March 2009

Experimental data on the kinetics of methane hydrate formation in aqueous electrolyte solutions are reported. The experiments were carried out in a semi‐batch stirred tank reactor in three NaCl and two KCl solutions as well as in a solution containing a mixture of NaCl and KCl at three different nominal temperatures from 270 to 274 K and at pressures ranging from 3.78 to 7.08 MPa. The kinetic model developed by Englezos et al. (1987a) was adapted to predict the growth of hydrates. The model is based on the crystallisation theory coupled with the two‐film theory for gas absorption in the liquid phase. The kinetic rate constant which appears in the model was that obtained earlier for methane hydrate formation in pure water. The effect of the electrolytes was taken into account through the computation of the three‐phase equilibrium conditions and the corresponding fugacities. Overall, the model predictions match the experimental data very well with the largest prediction error being less than 10%.
Xanthan production in an external‐circulation‐loop airlift fermenter
Authors: Kessler Wolfgang R. , Popović Milan K. , Robinson Campbell W.
Published: March 2009

A preliminary study of xanthan production by Xanthomonas campestris was performed in an external‐circulation‐loop airlift (ECL‐AL) fermenter. An average of 25 g/L xanthan of good viscosity characteristics was obtained in a total fermentation time of 49 hours. Oxygen limitation was observed after 36 hours of fermentation time. It is conclusively demonstrated that the ECL‐AL fermenter can be used to economically produce xanthan. The key operating and design features are the liquid height, downcomer‐to‐riser cross‐sectional area ratio (AD/AR) and the orfice diameter of the air sparger.
Etude de l'influence des paramètres de fonctionnement d'un réacteui électrochimique à lit fixe conique
Authors: Benzina M. , Ratel A. , Lacoste G.
Published: March 2009

La récupération des ions métalliques en solution diluée peut être effectuée à l'aide d'un réacteur électrochimique à cathode volumique. Ce travail fait suite à l'étude relative aux réacteurs électrochimiques à tronc conique à lit transporté. Il intéresse plus précisément l'influence des pararnètres de fonctionnement tels que le sens de l'écoulement (ascendantou descendant), et l'angle du cône. Cette étude a permis de dégager les paramètres géométriques conduisant aux meilleures performances du réacteur, travaillant au courant limite de diffusion.
Steady‐state methanation kinetics over a Ni/Al2O3 catalyst
Authors: Yadav Rajiv , Rinker R. G.
Published: March 2009

Extensive kinetic data for the methanation reaction over a Ni/Al2O3 catalyst were obtained in a specially designed gradientless reactor operating at steady state. The reactor pressure was 101.3 kPa, and three temperatures were used, namely, 503, 513 and 523 K. The following three‐parameter phenomenological model based on a proposed Langmuir‐Hinshelwood mechanism adequately describes the data: r = L2 K3 K40.5 k5 P0.5H2 Pco/ [1 + K3 (k5 / k6)Pco + K40.5 P0.5H2 ]2

With dissociative adsorption of hydrogen and hydrogen‐assisted dissociation of adsorbed carbon monoxide, the postulated mari is the CH surface group, and the rds is the hydrogenation of the surface CH group.
Sulfation of high purity limestones under simulated pfbc conditions
Authors: Krishnan S. V. , Stratis  , Sotirchos V.
Published: March 2009

The direct sulfation of three high purity limestones, all having more than 95% CaCO3 but differing in petrographic texture, was studied in a thermogravimetric analyzer under simulated PFBC (Pressurized Fluidized‐Bed Combustion) conditions, that is, in the presence of enough CO2 to prevent decomposition of CaCO3. Experiments were carried out over a wide range of particle size (53‐350 μm) at two temperatures (750 and 850°C), and two concentrations (1500 and 6000 mL/m3 (ppmv) SO2). The particle size and temperature had a strong influence on the variation of the conversion with time. In contrast, the effect of concentration was rather marginal over the whole duration of the process, and the analysis of the initial reaction rate data gave a reaction order of 0.4, with respect to SO2, for all solids. The measured reaction rates were compared with those obtained in a past study for the sulfation of the calcines of the three solids under similar conditions. The initial rate of the calcine‐SO2 reaction was found to be higher than that of the limestone‐SO2 reaction, but since the former drops sharply as the pores at the external surface of the particles are filled with solid product, higher conversions may be obtained in some cases during direct sulfation for large reaction times.
Calculation of pure compound saturated enthalpies and saturated volumes with the PRSV equation of state. Revised k1 parameters for alkanes
Authors: Proust  , Meyer E. , Vera J. H.
Published: March 2009

The Stryjek‐Vera (1986a) modification of the Peng‐Robinson (1976) equation of state has been used to predict heats of vaporization, enthalpies of saturated phases and saturated volumes for pure compounds ranging in molecular complexity from diatomic gases to compounds showing polarity and association.

Heats of vaporization at the normal boiling temperature are reproduced within 2% for the majority of the compounds tested. Similar results were obtained for the enthalpy of the saturated phases. Revised k1 parameters of the PRSV equation of state are reported for alkanes.

An empirical correction has been developed for calculating saturated liquid volumes from the liquid volumes given by the PRSV equation of state. For the range of reduced temperatures from 0.5 to 0.99, deviations from experimental values are smaller than 4%. Saturated vapor volumes calculated from the PRSV equation of state were found to be satisfactory for most technical calculations.
Hydrodynamics and power consumption of a reciprocating plate gas–liquid column
Authors: Lounes Mustapha , Thibault Jules
Published: March 2009

An experimental program has been initiated to use a reciprocating plate column for aerobic fermentations. This paper reports the results of the initial phase consisting of the hydrodynamic studies and the evaluation of the power consumption as a function of the level of agitation and gas superficial velocity. The variation of the gas holdup is presented and compared to a correlation. It is shown that a simple correlation can predict adequately the gas holdup when water is used. The power consumption, necessary for scale‐up and design considerations, was evaluated using the pressure variation at the base of the column, the pressure difference across the column and the force exerted on the central shaft to reciprocate the plate stack. Results for the power consumed by the fluid mixture obtained with the three methods are presented and analyzed. The three methods give approximately the same value of the power consumption.
Characteristics and so2 capture capacities of sorbents prepared from products of spray‐drying flue gas desulfurization
Authors: Ho Ch'Un‐Sung , Shih Shin‐Min
Published: March 2009

The characteristics and the SO2 capture capacities of sorbents prepared from products of spray‐drying flue gas desulfurization (FGD) have been studied. Sorbents were prepared by first slurrying Ca(OH)2 and CaSO3 and/or CaSO4 with and without the addition of fly ash and then drying. Compared to the use of pure Ca(OH)2, the SO2 capture and Ca(OH)2 utilization decreased for sorbents prepared without fly ash and increased for sorbents with fly ash. Flakelike ill‐crystallized tobermorites were observed for all the sorbents containing fly ash. In addition, significant amounts of needle‐shape Ca4Al2(OH)12SO4 . 6H2O and Ca6Al2 (OH)12(SO4)3 . 26H2O (ettringite) were also observed for the sorbents containing CaSO3 and/or CaSO4. These newly formed compounds dissociated into CaSO3 . 0.5 H2O and inert precursors upon sulfation, and were responsible for the high SO2 capture capacities and Ca(OH)2 utilizations of the sorbents prepared with fly ash.
Modified oil agglomeration process for coal beneficiation. iv. pilot‐plant demonstration of the simultaneous grinding‐agglomeration process
Authors: Trass Olev , Vasquez E. R. , Campbell P. D. , Gandolfi E. A. J. , Koka V. R.
Published: March 2009

Simultaneous grinding and agglomeration (SGA) in the novel Szego Mill allows significant simplifications and energy savings. The excess grinding energy is used for mixing and agglomerate formation. Results are reported over a range of operating conditions. The SGA process has been demonstrated in the laboratory and in a 12 tonnes/day pilot plant with satisfactory results. The economics of coal beneficiation for slurry fuel preparation is considered.
Near‐critical phase behavior of mixtures using equations of state
Authors: Firoozabadi Abbas , Arbabi Sepehr , Dindoruk Birol
Published: March 2009

Phase behavior calculation of hydrocarbon mixtures and gas condensate systems in the near‐critical and retrograde regions is of a fundamental nature. Current approaches using an equation of state cannot be used reliably to calculate the phase behavior of gas condensates in the near‐critical region, and the use of complicated mixing rules may not yield reliable results.

In this paper, we propose to modify the binary interaction coefficients. These coefficients, contrary to the current assumption, may not be constant (even at a given temperature), but are a function of the distance to the critical point of the system. When this variation is accounted for, significant improvement in the description of the phase behavior around the critical point can be obtained.
Mass transfer study in a pulsed bed electrode ‐ application to the electrodeposition of a poly(dibenzo‐18‐crown‐6) film
Authors: Lebolay N. , Guilland J. F. , Ricard A.
Published: March 2009

The polymerization of dibenzo‐18‐crown‐6 has been carried out in an electrochemical reactor containing a granular electrode percolated by a pulsed solution. The influence of different parameters (pulse frequency, permanent flow velocity of the electrolytic solution, particle diameter and bed height) on the mass transfer has been studied. A correlation between the reduced mass transfer coefficient and the Strouhal number has been established. The maximum mass transfer coefficient and the maximum Strouhal number have been determined as a function of the Galilee number. The correlation predicts well the mass transfer coefficient over a larger range of the variables than previously achieved.
Hysteresis effects in countercurrent gas‐liquid flow limitations in a vertical tube
Authors: Shoukri M. , Abdul‐Razzak A. , Yan C.
Published: March 2009

New experiments on air‐water countercurrent flow limitations in a vertical pipe are presented. The experiments were carried out to investigate the effect of test procedure on the occurrence of the two countercurrent flow limitations; namely the onset of flooding and complete carry‐up limits. The results revealed the existence of significant hysteresis effects at both limits particularly for high liquid feed rate. For low liquid feed rate, hysteresis effects were only observed at the complete carry‐up limit. Some associated visual observations are reported and the results were empirically correlated and compared with recent data obtained by others.
Drag on non‐spherical particles in non‐newtonian fluids
Authors: Rodrigue D. , Chhabra R. P. , de Kee D.
Published: March 2009

Extensive experimental results on the free fall of a range of non‐spherical particles such as square bars, cylinders, spheres and crushed rock chips in Newtonian, inelastic, viscoelastic and Boger fluids are presented. It is demonstrated that the use of a volume equivalent sphere diameter in addition to a shape factor provides an adequate approximation for the non‐sphericity of particles used in this study. The applicability of two rheological models, namely, the power‐law and the Carreau viscosity model has been examined in representing the drag coefficient results. Appropriate predictive expressions of the drag coefficient as a function of the particle Reynolds number and the Deborah number, encompassing wide ranges of rheological and kinematic conditions, are presented.
Determination of thermal parameters of non‐spherical particles in a packed bed from svstem response analysis in the time domain
Authors: Doan H. D. , Brown R. B. , Davidson V. J. , Otten L.
Published: March 2009

The thermal conductivity and the particle‐to‐fluid heat‐transfer coefficient for peanut‐shaped polyester particles in a packed bed were determined simultaneously using the pseudo‐random binary noise sequence (PRBNS) response technique. The modified Dispersion‐Concentric (D‐C) model was applied to beds packed with the non‐spherical particles. A time domain method, using the convolution integral, was developed for removing the effects of the bed ends and the transducer time lag on the experimental responses. Parameter estimation was performed in the time domain, using a simplex method to fit the thermal response calculated from the parametric D‐C model to the experimental response curve. The particle‐to‐fluid heat transfer coefficient in the bed was determined to be 106 W/m2. K at an interstitial fluid velocity of 2.0 m/s. The thermal conductivity of polyester was 0.22 W/m. K at 313 K.
Reaction kinetics of rye straw for thermnochemical conversion
Authors: Ghaly A. E. , Ergüdenler A.
Published: March 2009

Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were conducted on two common types of rye straws (Danko and Kustro) at a heating rate of 20°C/min in an oxidizing atmosphere (15% oxygen and 85% nitrogen, by volume) between ambient temperature and 700°C. The two step nature of the TGA curves and the dual peak characteristics of the DTA curves showed that rye straw had two distinct reaction zones. The initial degradation temperatures, the residual mass at 700°C, the thermal degradation rates in the first and second reaction zones and the kinetic parameters of each reaction zone (order of reaction, activation energy and pre‐exponential factor) were determined. Higher thermal degradation rates were observed in the first reaction zone as compared to those in the second reaction zone.
Estimating parameters in nonlinear rate equations
Authors: Watts Donald G.
Published: March 2009

Reaction rate equations with coefficients that have an Arrhenius dependence on temperature require nonlinear procedures to obtain parameter estimates. Estimates are important, but of equal importance are their measures of plausibility. The simplest measures, in the form (estimate ± limits), are based on linear approximations, which can be, and often are, highly misleading. But there is no need to use approximations because modern statistical profiling techniques can produce accurate intervals very efficiently. Profiling also provides valuable insight into the estimation situation by revealing how models can be simplified. Strategies are given for model reformulation and parameter transformation to produce models with well‐behaved estimates.
Friction and heat and mass transfer for turbulent pseudoplastic non‐newtonian fluid flows in rough pipes
Authors: Kawase Y. , Shenoy A. V. , Wakabayashi K.
Published: March 2009

Friction factor and heat and mass transfer coefficient correlations are developed for turbulent pseudoplastic (purely viscous or inelastic) non‐Newtonian fluids flowing through rough pipes.

A correlation for friction factor which is applicable in the region of transition from the smooth to the fully‐rough regime is proposed. It is obtained by adding the two correlations for the limiting situations, i.e. smooth pipes and fully‐rough pipes. The predictions of the proposed correlation are compared with published experimental data and other previous correlations.

A model for heat and mass transfer is developed on the basis of the Levich three‐zone model. It is found that the proposed model is capable of predicting satisfactorily heat and mass transfer coefficients for Newtonian and pseudoplastic non‐Newtonian fluid flow in rough pipes.
Prediction of surface tension of naphtha reformate using UNIFAC
Authors: Darwish E. I. , Al‐Sahhaf T. A. , Fahim M. A.
Published: March 2009

The surface tension of naphtha reformate cuts (60−170°C) were predicted using a modified UNIFAC group contribution method. The naphtha was distilled into eleven cuts of 10°C intervals to obtain narrow boiling range cuts. The surface tensions were determined in the temperature range 10−50°C and were compared with predicted values. A standard deviation of 5.9% was found using this method, versus 3.7% when the corresponding states method was used over the temperature range of 60−170°C. However, for the higher temperature range of 140−170°C, this method gave a standard deviation of 2.9% versus 7.6% for the other method.
Transfert de matière entre une nappe de mercure et des jets liquides immergés, simples ou multiples
Authors: Bensmaili A. , Coeuret F.
Published: March 2009

On a déterminé expérimentalement, par une méthode électrochimique, le coefficient moyen de transfert de matière entre des jets circulaires immergés verticaux de liquide, uniques ou multiples, et une nappe horizontale de mercure placée sous ces jets. Cette nappe est déformée par l'impact des jets et sa surface se trouve augmentée d'au maximum 30%. Des corrélations des résultats sont proposées. Dans le cas de jets uniques, le problème se trouve décrit d'une manière analogue à celui du transfert de matière dans une couche limite laminaire développée sur une plaque plane. Dans le cas de jets multiples, les corrélations sont empiriques, mais un support théorique a été considéré pour les jets turbulents.
Methane oxidative coupling over promoted Pb/Ca catalysts
Authors: Zhou Bing , Mcfarlane Richard A. , Smith Kevin J.
Published: March 2009

A series of Pb/Ca catalysts, promoted with Li, K and La, and prepared by different procedures, have been examined for the oxidative coupling of methane. The Li promoted Pb/Ca had the highest C2 selectivity and yield of the catalysts studied, including the unpromoted Pb/Ca. For the Li/Pb/Ca catalyst, CO2 added to the feed resulted in a decreased CH4 conversion and an increased C2 selectivity. Addition of H2O to the feed with the same catalyst, increased C2 yield. These effects are discussed in terms of deactivation and regeneration of the active sites by CO2 and H2O, respectively.
The solubility of CO2 in a 30 mass percent monoethanolamine solution
Authors: Jou Fang‐Yuan , Mather Alan E. , Otto Frederick D.
Published: March 2009

The solubility of CO2 in a 30 mass % monoethanolamine (MEA) solution has been measured at eight temperatures between 0 and 150°C at partial pressures of CO2 ranging from 0.001 to 20,000 kPa. The data have been correlated using the Deshmukh‐Mather (1981) model.
Small‐Molecule Inhibitors of Store‐Operated Calcium Entry
Authors: Sweeney Zachary K. , Minatti Ana , Button Donald C. , Patrick Silvia
Published: March 2009

Molecules that inhibitstore‐operated calcium entry (SOCE) are potentially useful immunomodulating agents. The identification of proteins involved in this pathway may further enable the identification of selective inhibitors. Herein we document some examples of the small‐molecule inhibitors of SOCE that have been reported to date. We also describe methods that were used to characterize the mechanism of action of these inhibitors.

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Controlled variation in intracellular calcium concentration is a key component of the immune response signaling pathway in lymphocytes. Store‐operated calcium entry (SOCE) in these cells provides a prolonged increase in cytoplasmic Ca2+concentrations and ultimately leads to the production of pro‐inflammatory cytokines. Molecules that inhibit SOCE could therefore be useful immunomodulating agents for the treatment of rheumatoid arthritis, psoriasis, inflammatory bowel disease, and other conditions. Although the presence of the SOCE signaling pathway in lymphocytes and other cells involved in the immune response has been known for many years, key proteins involved in SOCE were identified only recently. The identification of these proteins may further enable the identification of agents that inhibit SOCE without affecting other cellular processes. This contribution documents representative examples of the small‐molecule inhibitors of SOCE that have been reported to date. Where possible, methods that were used to characterize the mechanism of action of the inhibitors are also described.
Preparation of Remote NHC Complexes of Rhodium(I) and Gold(I) by Ligand Transfer
Authors: Strasser Christoph E. , Stander‐Grobler Elzet , Schuster Oliver , Cronje Stephanie , Raubenheimer Helgard G.
Published: March 2009

The rNHC complexes (5‐butyl‐1,2‐dimethylpyridin‐4(1H)‐ylidene)Cr(CO)5 (1), as well as the novel compounds (1,2‐dimethyl‐5‐phenylpyridin‐4(1H)‐ylidene)M(CO)5 (2, M = Cr; 3, M = W) and (1‐methylpyridin‐4(1H)‐ylidene)Cr(CO)5 (7) were prepared from Fischer carbene complexes. Reaction of 1 with [Rh2(μ‐Cl)2(CO)4] then afforded the first rNHC RhI complex, 4. Transfer of the ligand in 2 to Ph3PAu+ afforded the cationic rNHC gold complex, 5 and reaction of 3 and 7 with [AuCl(tht)] gave the neutral rNHC–AuCl complexes 6 and 8. The compounds were characterised by IR and multinuclear NMR spectroscopy as well as mass spectrometry. The crystal and molecular structures of the remote pyridinylidene complexes 3, 4, 5, 6 and 8 were determined by single‐crystal X‐ray diffraction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Study of interaction in bioindication research on tobacco plant injuries caused by ground level ozone
Authors: Kayzer Dariusz , Borowiak Klaudia , Budka Anna , Zbierska Janina
Published: March 2009

Tropospheric ozone is one of the most phytotoxic air pollutants. Its concentration has increased over recent decades. Bioindication methods could help to measure ozone levels in places where automatic methods are not available. The investigations described were carried out in the city of Poznan (Poland) and in its vicinity, using tobacco plants as a bioindicator for ozone. Plants were located at 10 sites during the years 2002–2004, and visible ozone injuries were assessed. Statistical methods based on multidimensional models were used to interpret the results. The aim of this investigation was to evaluate the level of ozone‐related injury to the 5th tobacco leaf, using multivariate analysis of variance. Differences of leaf injury levels between certain years and exposition sites were especially analyzed. The results of multivariate analysis were presented graphically in the space of canonical variates. The described study shows that multidimensional analysis of variance using canonical variates appears be an appropriate technique for testing hypotheses about differences between years and exposition sites as regards 5th leaf injury degree. The studies revealed a high variability of tobacco leaf injury caused by ozone in Poznan and its vicinity. Copyright © 2009 John Wiley & Sons, Ltd.
Effect of ambient air pollution on respiratory illness in Hong Kong: a regional study
Authors: Shao Quanxi , Wong Heung , Ip Wai‐Cheung , Li Ming
Published: March 2009

It is widely agreed that the exposure in air pollution causes serious respiratory illnesses and that the weather may also contribute to the seriousness. However, it is difficult to quantify the effects of pollutants and weather conditions due to the high unknown nonlinearities in the impact of these environmental and weather factors on the illnesses and possible interactions amongst these factors. In this paper, the multiple index model is employed to explore such relationship in Hong Kong. Time lags are incorporated to address the incubative period from the impact to the symptoms. We found that the weather factors are important in triggering the illnesses. However, the similarity in the number of illnesses and weather pattern causes the seriousness of ambient air pollutants being distorted. We restrict the time periods in winter and summer in which the weather is relatively stable. We then clearly identified the importance of air pollutants to respiratory illnesses. The results also revealed the difference between sub‐regions. By comparing with linear and several nonlinear models, we understood that the nonlinear relationship is supportive. We also found that our model is better than the single index model, indicating that further fine‐tuning is necessary to achieve better forecasting results. Copyright © 2009 John Wiley & Sons, Ltd.
The SNRI venlafaxine improves emotional unawareness in patients with post‐stroke depression
Authors: Cravello Luca , Caltagirone Carlo , Spalletta Gianfranco
Published: March 2009

Objective

Patients with stroke have a high prevalence of depression and unawareness of emotions or alexithymia. Here we investigated the effects of the serotoninergic and noradrenergic reuptake inhibitor (SNRI) venlafaxine in comparison with the SSRI fluoxetine on alexithymia severity in patients with DSM‐IV post‐stroke major depressive‐like episode (PSD).

Methods

Fifty inpatients with first‐ever stroke and PSD were consecutively enrolled in this randomized open‐label study. Twenty‐five were treated with the SNRI venlafaxine SR (75–150 mg/die), and 25 with the SSRI fluoxetine (20–40 mg/die). All patients were assessed at day 0, and after 1, 2, 4, 6, and 8 weeks, using the Mini‐Mental State Examination, the Hamilton Depression Rating Scale, and the Toronto Alexithymia Scale (TAS‐20).

Results

Patients treated with fluoxetine and those treated with venlafaxine showed similar improvement in depressive symptoms. However, patients treated with venlafaxine had a greater improvement on alexithymia severity than those treated with fluoxetine. The effect of venlafaxine on unawareness of emotions was evident in patients with alexithymia (TAS‐20 ≥ 61) at the baseline and in those without alexithymia (TAS‐20 < 61).

Conclusions

Antidepressants acting on both the serotoninergic and noradrenergic systems might represent a valid resource not only for the treatment of depression but also for improving emotional unawareness in stroke patients. Copyright © 2009 John Wiley & Sons, Ltd.
Molecularly imprinted polymer for the determination of trace ractopamine in pork using SPE followed by HPLC with fluorescence detection
Authors: Wang Shuo , Liu Li , Fang Guozhen , Zhang Chao , He Jinxing
Published: March 2009

In this study, a molecularly imprinted functionalized polymer for the selective separation of ractopamine (RAC) was prepared by combining a surface molecular imprinting technique with a sol–gel method process. The polymer was evaluated by static, kinetic adsorption, and selective experiments. Results indicated that the molecularly imprinted polymer had high adsorption capacity, selective ability, and fast mass transfer rate. The polymer was applied for the determination of trace RAC through online SPE‐HPLC. With a sample loading flow rate of 2 mL/min, the enhancement factor of 516.26 and the LOD (S/N = 3) of 4.6 ng/L were achieved, respectively, and the linear range of the calibration curve was 0.04–18 μg/L with r2 >0.99. The RAC in pork was determined at three spiked levels (0.5, 1, and 2 ng/g) with recoveries ranging from 55.86 to 67.28%.
A discretized analytical solution for fully coupled non‐linear simulation of heat and mass transfer in poroelastic unsaturated media
Authors: Malekzadeh F. Arfaei , Pak A.
Published: March 2009

Mathematical simulation of non‐isothermal multiphase flow in deformable unsaturated porous media is a complicated issue because of the need to employ multiple partial differential equations, the need to take into account mass and energy transfer between phases and because of the non‐linear nature of the governing partial differential equations. In this paper, an analytical solution for analyzing a fully coupled problem is presented for the one‐dimensional case where the coefficients of the system of equations are assumed to be constant for the entire domain. A major issue is the non‐linearity of the governing equations, which is not considered in the analytical solution. In order to introduce the non‐linearity of the equations, an iterative discretized procedure is used. The domain of the problem is divided into identical time–space elements that cover the time–space domain. A separate system of equations is defined for each element in the local coordinate system, the initial and boundary conditions for each element are obtained from the adjacent elements and the coefficients of the system of equations are considered to be constant in each step. There are seven governing differential equations that should be solved simultaneously: the equilibrium of the solid skeleton, mass conservation of fluids (water, water vapor and gas) and energy conservation of phases (solid, liquid and gas). The water vapor is not in equilibrium with water and different phases do not have the same temperature. The governing equations that have been solved seem to be the most comprehensive in this field. Three examples are presented for analyzing heat and mass transfer in a semi‐infinite column of unsaturated soil. Copyright © 2009 John Wiley & Sons, Ltd.