bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of active metal sites in metal oxide catalysts by selective gas chemisorption
Authors: Parkash S.
Published: March 2009

Chemisorption behavior of hydrogen, carbon monoxide, nitric oxide and ethylene on three iron and three cobalt moly catalysts has been investigated in an attempt to determine active metal sites. Mode of adsorption for nitric oxide and of ethylene whether of associative or dissociative nature on the metal surface has been discussed in relation to hydrogen and carbon monoxide chemisorption. There appears to be a definite correlation between the amounts of hydrogen and carbon monoxide (VH/VCO = 1), between carbon monoxide and nitric oxide (VNO/VCO = 1.2) as well as between carbon monoxide and ethylene (CCO/V = 2) chemisorb. ed. The data suggest that the selective chemisorption behavior of nitric oxide and of ethylene should provide a suitable method to determine active metal sites in metal oxide catalysts.
Characterization of zeolitic acidity I. The cracking of 2 mole % n‐Butane over a fixed zeolite bed
Authors: Rastelli H. , Lok B.M. , Duisman J. A. , Earls D.E. , Mullhaupt J.T.
Published: March 2009

The use of a two mole percent n‐butane in helium stream in a fixed bed mini‐reactor at a temperature of 500°C over a zeolite bed (20 to 40 mesh and ≤ 5 grams in weight) was found to be a good tool for characterizing zeolitic acidity. In a broad spectrum of various kinds of zeolites tested, the test results are especially useful in differentiating the extremely active materials from the very active ones. Among the zeolites tested, the decreases in the order of HΩ > H‐Zeolon > NH4‐ZSM‐5 > NH4Y (thermally modified) > NH4‐erionite (thermally modified) > > HKL > NH4Y > NaY ˜ amorphous silica‐alumina. The calculated first order rate constant covered a range from over 100 to 0.5 cm3/g•min.
Turbulent mixing in free swirling jets
Authors: Grandmaison E. W. , Becker H. A.
Published: March 2009

Marker nephelometry was used to study the nozzle fluid concentration field of free swirling turbulent jets. Swirl was generated by guide vanes in a 7.14 cm diameter nozzle with swirl numbers of 0.22, 0.36, 0.61 and 0.68 as determined by direct measurement of the linear and angular momentum fluxes for the jets. The parameters measured include those describing the self‐preserving forms of the mean concentration field, the intensity and integral scale of the concentration fluctuations, and the intermittency for the jets without internal recirculation (swirl number < 0.6). Results show that swirling jets without internal recirculation are very similar in structure. The data for the two jets with internal recirculation zones are given as contour maps describing the mean concentration and fluctuation intensity fields. The results as a whole describe jets with weak to moderate swirl and indicate trends to be expected for jets with strong swirl.
Analysis of fluid friction in dense‐phase pipeline flow
Authors: Wilson Kenneth C. , Brown Nigel P.
Published: March 2009

In horizontal dense‐phase slurry transport the pressure gradient is the sum of two components. The particle‐contact component, which was evaluated previously, is independent of flow velocity. It is now shown that the second component can be found in terms of a friction factor which depends on a Reynolds number based on flow velocity and particle diameter. The form of the dependence has been evaluated from theoretical considerations, and the results show a gratifying accord with the experimental data. In addition to dense‐phase flow, the findings should be applicable to other cases with a sliding bed of solids.
Study of the development of mass transport paths via an electrochemical flow visualization technique
Authors: Quraishi M. S. , Fahidy T. Z.
Published: March 2009

Mass transport patterns in natural convection generated in non‐flow cells at horizontal electrodes have been studied by an electrochemical visualization technique. Sharp colour changes in the thymbol‐blue indicator during electrolysis, due to local pH‐variations occurring in the cathodic boundary layer allow direct tracing of the propagation of flow filaments into the electrolyte bulk. The results provide direct evidence for the enhancing effect of magnetic fields on electrolytic mass transport rates and for the existence of horizontal velocity components of appreciable size at the convective surfaces.
Étude des caractéristiques de l'ecoulement créé par une turbine à Barreaux croisés dans une cellule de flottation — Influence du nombre de barreaux et de la viscosité Du liquide ii • puissance consommée et analyse spectrale
Authors: Costes J. , Alran C. , Couderc J. P.
Published: March 2009

Les influences du nombre de barreaux d'une turbine à barreaux croisés et de la viscosité du liquide sur les résultats de l'analyse spectrale du signal anémométrique dans une cellule de flottation ont été déterminées. Les spectres de fréquence et coefficients d'autocorrélation, les échelles intégrales temporelles et spatiales, le coefficient de diffusion turbulente, le taux de dissipation locale d'énergie et la microéchelle de turbulence ont été précisés et leurs caractéristiques commentées.
Some characteristics of concentration fluctuations in free turbulent jets
Authors: Grandmaison E. W. , Rathgeber D. E. , Becker H. A.
Published: March 2009

Becker, Hottel and Williams have employed marker nephelometry to determine many characteristics of the nozzle fluid concentration field of the round turbulent free jet: the mean concentration, concentration fluctuations, intermittency factor, spectrum and correlation functions, and integral scales. In the present work a much larger jet nozzle was employed, 7.14 cm throat diameter compared to 0.635 cm in the reference, and the Reynolds number was correspondingly greater, around 270,000 compared to 54,000. The results support Becker et al's findings and extend the range of the data. In particular, the spectrum of the concentration fluctuations has been measured into the viscous convective subrange where a (‐1) power mode dependency on wave number is indicated, as expected for the slow diffusing smoke marker. Other new measurements include the skewness, kurtosis, and probability density function of the concentration fluctuations.
Bubble deformation in high‐velocity gas injection
Authors: Anagbo P. E.
Published: March 2009

When pressurised gas is injected into liquid at high velocity, the bubbles of dispersion are not exactly spherical as normally assumed in theory. High speed photographs of the dispersion show that the bubbles are spheroidal and distinctly prolate in the direction of gas flow.

A mechanism of bubble deformation based on the dissipation of the kinetic energy of the injected gas is proposed in this work. The theoretical results are compared with experimental measurements of bubble deformation during high‐velocity injection of air and hydrogen through submerged plate orifices into water.
Hydraulic behavior of synthetic non‐woven filter fabrics
Authors: Rollin A. L. , Denis R. , Estaque L. , Masounave J.
Published: March 2009

The filtration performance of non‐woven thick synthetic membranes used as filter fabrics is predicted from a proposed analytical method. The morphological analysis of many commercial fabrics has been utilized to identify internal structure parameters responsible for their hydraulic properties and also to predict the water permeability and the retention of particles in these fabrics.

Experimental filtration tests were performed to gather data on the water permeability used in predicting clogging level. Also fibres' density and pore size histograms of fabrics were measured with an Image Analyser and a relationship was developed between the water permeability and the fibres' density.

Finally it was found that the pore size histogram of non‐woven fabrics of thickness greater than 1.5 mm could be calculated simply by measuring its water permeability and using an empirical correlation.
Rheology and tensile properties of polypropylene reinforced with glycerol‐treated mica
Authors: Juskey Victor P. , Chaffey Charles E.
Published: March 2009

Mica platelets were left untreated or coated with glycerol at 1%. 5% or 10% by mass, and extruded in carboxyl‐modified polypropylene at volume fractions up to 20%, and at temperatures between 468 and 528 K. At a shear rate of 10 s and at 500 K, the Einstein coefficient decreased from 2.1 when glycerol was added. The flow behavior index, ranging between 0.57 and 0.45, decreased when the shear rate or amount of mica or of glycerol was increased, while the opposite occurred when the temperature was raised. In the solid state, the tensile modulus increased, but the tensile strength was degraded.
An overview of discrete stochastic controllers: Generalized PID algorithms with dead‐time compensation
Authors: Harris T. J. , Macgregor J. F. , Wright J. D.
Published: March 2009

Digital computer control systems have enabled use of a wide variety of different algorithms compared with the classical analog proportional‐integral‐derivative controllers. Design techniques have been presented for many of these in diverse areas of the literature. Some algorithms are designed to give minimum time responses, or to give specified closed loop responses, or to satisfy classical guidelines for stability. By contrast, the design of discrete optimal stochastic controllers is not based on considerations such as stability, frequency response, or dead‐time compensation properties, but rather on optimizing some criterion of performance such as the output error variance. Therefore, it is of interest to investigate how these controllers behave with respect to some of the more traditional ways of evaluating or designing controllers. In this paper, both intuitive and theoretical arguments are presented to illustrate the very desirable properties of these controllers and their relationship to many other algorithms. In particular, they are shown to contain proportional‐integral‐derivative terms and to be related to other well‐known controllers, to have optimal compensation for process dead‐time and optimal filtering properties, and to have very desirable stability and frequency response characteristics. In this sense, the paper provides a unifying overview of univariate stochastic controllers.
Absorption of chlorine into aqueous sodium carbonate solutions and desorption of carbon dioxide
Authors: Hikita H. , Asai S. , Konishi Y. , Seo K.
Published: March 2009

The absorption of pure chlorine into aqueous sodium carbonate solutions accompanied by the desorption of carbon dioxide was studied both theoretically and experimentally. The absorption rates of chlorine and the desorption rates of carbon dioxide were measured at 25°C using a baffled agitated vessel operated batchwise. The experimental results were analyzed with the chemical absorption theory based on the Lévěque model. The measured absorption and desorption rates were in good agreement with the theoretical predictions.
Effectiveness and performance of a catalyst pellet with bimodal kinetics
Authors: Chitnis G. K. , Wolf E. E.
Published: March 2009

A theoretical analysis of the performance of a bimodal catalyst pellet which contains two different active components exhibiting different kinetics is presented in this paper. The isothermal interphase‐intraphase effectiveness of such bimodal catalysts with a bimolecular Langmir type kinetics (i.e. noble metal) and a first order kinetics (i.e. base metal oxide) is coupled with the continuity equation for a fixed bed reactor and a continuously stirred tank catalytic reactor. The catalysts with mixed mode kinetics exhibit a behaviour that is less affected by concentration changes than the single component catalyst. Reactor performance depends on the noble metal fraction but not in direct proportion. Thus in some cases conversion reaches high levels at fractional values of noble metal loadings which would in theory allow for equivalent performance with savings in noble metal component.
Acidophilic fungus SCP from peat hydrolyzate
Authors: Boa Jacques M. , Leduy Anh
Published: March 2009

An unidentified newly isolated acidophilic fungus was cultivated in peat hydrolyzate for potential use as single‐cell protein (SCP). At the optimal medium composition of (NH4)2SO4 0.5%. K2HPO4 0.5%, MgSO4 0.04%, and an initial pH of 2.5, the maximum biomass concentration of 10.4 g/L and the total carbohydrate reduction of 69.7% were obtained from the batch cultivation in an open‐pond bioreactor. The fungal biomass contained 24.3% protein, 1.7% lipid, 61.2% carbohydrate and 12.8% ash on the dry weight basis. The content of lysine, threonine, methionine, leucine and isoleucine in peat hydrolyzate‐grown fungus was superior to the FAO standard.
Interfacial tensions of oil, water, chemical dispersant systems
Authors: Mackay Donald , Hossain Khon
Published: March 2009

Oil‐water interfacial tension measurements are reported for systems of crude oils, distilled and salt water, and chemical dispersants, using the spinning drop technique. By varying the amount of dispersant and the volumetric ratio of water to oil it is possible to deduce an effective oil‐water partition coefficient for the interfacial tension reducing species and to suggest a relationship between the extent of interfacial tension reduction and dispersant concentration. The implications of the results in assessing the mechanism and effectiveness of the chemical dispersion process are discussed.
A method of estimating entropies of coals and coal liquids
Authors: Ikumi S. , Luo C. D. , Wen C. Y.
Published: March 2009

A method for estimating entropies of both solid and liquid fuels is proposed. An example showing calculation of availability of coal is presented. Entropy and availability of coal calculated are compared with those obtained by other methods. Deviations among different methods examined are discussed.
The nature of the active sites in cumene cracking on amorphous silica aluminas
Authors: Marczewski M. , Wojciechowski B. W.
Published: March 2009

We present evidence which indicates that the nature of the active sites is the same for amorphous catalysts as it is for crystalline alumina silicate cracking catalysts. The only differences we find in the various cracking catalysts lie in the total concentrations of active sites and in the ratio of Bronsted to Lewis sites.

In view of this, and because even zeolites have only a fraction of their cationic sites active in cumene cracking, we suggest that it is possible that a silica alumina catalyst could exist that is more active by as much as an order of magnitude than any catalyst presently available for cumene cracking.
Agitation de fluides pseudoplastiques par un agitateur bipale
Authors: Et J. Bertrand , Couderc J. P.
Published: March 2009

In the present work, results are given on the agitation of pseudoplastic fluids by a two‐blade stirrer; the method used has been a numerical analysis. The fluids simulated follow either the Ostwald de Waele Law or the Carreau's one. The (flow) streamlines, the velocity vector, the apparent viscosity, the stresses and the power consumption are presented. The Metzner‐Otto theory is checked and a correlation is proposed for the power number. Finally, some characteristic values obtained on the blade tips are indicated.
A mass transfer study of a new electrochemical reactor stirred by gases evolved at the counter electrode
Authors: Sedahmed G. H. , Shemilt L. W.
Published: March 2009

Mass transfer coefficients were measured for the deposition of copper from acidified copper sulphate solution at a horizontal cylinder cathode stirred by oxygen evolved at a horizontal lead anode placed below the cylinder. Variables studied were: oxygen discharge rate, electrolyte concentration and cylinder diameter. Oxygen discharge was found to increase the rate of mass transfer by a factor ranging from 1.5 to 5 over the natural convection value depending on the rate of oxygen discharge at the lead anode. The data were correlated by the equation: J = 25.0 Re−0.53

Mass transfer coefficients measured at an array of horizontal cylinders agreed with the results for single cylinders. A new electrochemical reactor built of a set of parallel arrays of horizontal cylinders and stirred by the counter electrode gases is proposed as offering an efficient way of stirring with no external stirring power requirement.
A study of agglomeration of coal‐ash in fluidized beds
Authors: Basu P.
Published: March 2009

Experimental data on agglomeration of coal‐ash particles in a fluidized bed have been presented. It has been observed that above the “initial sintering temperature”, the ash particles are defluidized at velocities above their minimum fluidization velocity. The expression for minimum fluidization velocity has been modified by including a force‐term due to the phenomenon of sintering in addition to those due to drag, gravity and kinetic energy.
The kinetics of absorption of so3 in calcium and magnesium oxides
Authors: Thibault J. Dean , Steward Frank R. , Ruthven Douglas M.
Published: March 2009

Results of an experimental study of the absorption of SO3 by CaO and MgO particles are reported. Uptake rates are shown to be controlled by intragranular diffusion and are essentially independent of gross particle size in the range 0.06‐0.33 mm. The data can be correlated by the swelling grain model of Georgakis et al.(12). The uptake rate in MgO is considerably faster than in CaO but this difference is shown to be attributable mainly to differences in grain size and porosity. Activation energies for diffusion of SO3 through the product layer are about 40 kJ/mol for both absorbents and diffusivities at 800 K are about 10−8. cm2. S−1. The results are discussed in relation to the development of an efficient dry scrubbing flue gas desulphurization process.
Ozonation of organic compounds in alkaline aqueous media
Authors: Imamura S. , Umena H. , Kawabata N. , Teramoto M.
Published: March 2009

Effect of pH on the aqueous phase ozonation of various organic compounds was investigated. The reaction was accelerated in alkaline media due to the formation of active hydroxyl radical by an interaction of ozone with hydroxide ion. However, in a strongly alkaline media (pH < 11.9), hydroxyl radical dissociated into less reactive oxygen ion and the efficiency of ozonation decreased. By means of the theory of gas absorption accompanied by chemical reaction, it was found that the rate of the decomposition of ozone in the presence of about 300 ppm of 1‐butanol was 5‐80 times larger than that catalyzed only by hydroxide ion in the pH range of 11‐13. Efficiency of ozonation showed that an optimum range of pH for the removal of total organic carbon was 9‐10.
Xylene isomerization by ZSM‐5 zeolite catalyst
Authors: Collins Dermot J. , Medina Roger J. , Davis Burtron H.
Published: March 2009

The larger pore LaY zeolite catalyst resembles homogeneous metal chloride and heterogeneous silica‐alumina acid catalysts since the results are consistent with isomerization being a series of intramolecular 1,2 shifts. On the other hand, isomerization with the smaller pore zeolite, ZSM‐5, is very different and the relative rate constants appear to be influenced by diffusion and/or shape selectivity. Disproportionation is a significant reaction with LaY but not with ZSM‐5 in the temperature range used for the present study. The small amount of trimethylbenzene formed at low conversions using ZSM‐5 is 1,2,4‐trimethylbenzene, also providing evidence of shape selectivity influencing the reaction products.
Liquefaction of wood by rapid hydropyrolysis
Authors: Beckman D. , Boocock D. G.
Published: March 2009

Poplar wood, when heated rapidly (70‐90 s) in water to 350°C and quenched, yields oil in 55 per cent mass yield. Approximately 75 per cent of the wood carbon and hydrogen is retained in the oil. The oil contains 25 per cent oxygen (wood contains 45 per cent). Extended reaction significantly lowers yields which are the same in the presence of both nitrogen and hydrogen atomsopheres. Nickel carbonate addition lowers yields significantly. Experiments have been limited to wood particles less than 35 mesh (0.73 mm grid) but heat transfer studies are being extended to larger particles.
Steady state and transient behavior in 1‐butene reactions over bismuth molybdate
Authors: Oliveira Margarida , Portela M. Farinha , Pires Maria Joäo , Ribeiro F. Ramôa
Published: March 2009

Pulse and continuous flow techniques were used to study 1‐butene reactions in the presence of oxygen over bismuth molybdate.

At 280°C and low 1‐butene partial pressures (2.1‐5.6 kPa), the activity increases with the pulse number and tends towards a constant level. At high 1‐butene partial pressures (40‐68 kPa), the activity decreases at the same conditions but tends also to stabilize. The butadiene selectivity increases and 2‐butene selectivities decrease in both cases and tend towards the selectivities observed with a continuous flow technique in steady state conditions.

At 350°C, the activity has a similar behavior for low pressures of 1‐butene, but for high pressures increasing activity occurs. For such a temperature the oxidative dehydrogenation selectivity decreases and the isomerization selectivities increase with respect to the pulse number, but tend also towards the values found in steady state flow operation.

Experiments at intermediate temperatures (300 and 320°C) show a coherent evolution. On other side, experimental results obtained using only 1‐butene as reactant in the absence of oxygen contributed greatly to clarification of the observed situation.

The results are discussed and interpreted in the context of the reaction mechanism.
The influence of gaseous chlorine on the chemical and catalytic properties of alumina
Authors: Marczewski Marek , Derewinski Miroslaw , Malinowski Stanislaw
Published: March 2009

The influence of gaseous chlorine on the chemical and catalytic properties of alumina was investigated. Cl2 reacts both with surface OH groups and with surface oxygen anions possessing electron‐donating power, forming new surface sites.

When such chlorine treatment is performed at a low temperature (293 K), both Lewis and Bronsted acid centres are formed. High temperature chlorination leads exclusively to Lewis acid sites. It is proposed that such Lewis sites are responsible for olefin isomerization reactions.
Investigation of a fixed‐bed pilot plant reactor by dynamic experimentation. Part 2. Simulation of reactor behaviour
Authors: Baiker Alfons , Bergougnan Michel
Published: March 2009

Data collected with forced uncorrelated sinusoidal changes of the process variables are used to simulate the behaviour of a non‐isothermal non‐adiabatic pilot plant fixed‐bed reactor. The test reaction applied is the hydrogenation of toluene to methylcyclohexane on an industrial nickel catalyst. A pseudo‐homogeneous two‐dimensional model as well as a one‐dimensional model are applied to describe the reactor behaviour. The model parameters are estimated by defining an objective function based upon residuals of the discretized differential equations instead of upon deviation from the observed variables. This procedure leads to a drastic reduction of computer expenditure. Measured and simulated temperature and concentration profiles are compared on the basis of a number of plots and fitting quality criteria. The model parameters estimated from data collected during dynamic runs are comparable to those obtained from a series of stationary experiments (23 experimental design). However, with the dynamic experiments the data necessary for modelling can be collected much more efficiently.
Simulation Mathématique de la Circulation de I'Air dans une Enceinte avec Ouvertures et Sources Chaudes Localisées
Authors: Dupuis Marc , Claude Méthot J. , Dernedde Edgar
Published: March 2009

La simulation mathématique de la circulation de I'air et du profil de température dans une enceinte rectangulaire avec plusieurs ouvertures et sources chaudes localisées a été réalisée sur ordinateurs. Une méthode numérique aux différenccs finies, combinée à un modéle simple de turbulence, a été utilisée pour réksoudre les équations différentielles de la conservation de la masse, de la quantité de mouvement et de I'énergie. Les calculs ont été effectués un nombre de Prandtl de 0.7, un nombre d'Archiméde d'environ 34 et le nombre de Grashof a atteint des valeurs de I'ordre de 3 × 109. Une comparaison entre les résultats numériques et ceux observés dans une maquette permet de conclure que le modtèle mathématique reproduit assez fidètlement I'écoulement de I'air et le profil de température.

L'effet combiné de la convection naturelle au voisinage des sources chaudes et de la convection forcée engendre une circulation complexe dans I'enceinte. Ces conditions d'opération ont été choisies dans le but d'Ctudier les conditions de la circulation de I'air et de la température dans les salles de cuves d'électrolyse de I'aluminium.
A model on the breakdown of crude oil gel
Authors: Ananda Rao B. M. , Mahajan S. P. , Khilar Kartic C.
Published: March 2009

A new model is proposed on the basis of the simultaneous decrease of build‐up yield stress and viscosity to describe the break down of crude oil gel. A set of two experiments conducted at different but under constant wall shear stress is required to compute the four parameters of the model. The model is verified with reported data.
Characterization of hydrodynamic parameters in rotating disc and oldshue‐rushton columns. Hydrodynamic modelling, drop size, hold‐up and flooding
Authors: Sharker S. , Phillips C. R. , Mumford C. J.
Published: March 2009

Flooding rates, dispersed phase hold‐up, hold‐up profile and drop‐size distribution were investigated in rotating disc and Oldshue Rushton 0.10 m diameter, 18 compartment columns with toluene‐water as the liquid‐liquid system. The axial dispersed phase hold‐up and the mean drop size in both contactors varied significantly with column height. The hold‐up profiles were correlated by semi‐theoretical models.
A thermodynamic analysis of the steam ejector, uranium leach, slurry‐to‐slurry heat exchanger
Authors: Sorensen P. F.
Published: March 2009

The primary chemical step in the recovery of uranium oxide (U3O8) from ore in South Africa's uranium plants is thesulphuric acid teaching of slurries of the ore in water. The reaction is promoted by live steam injection to elevate temperatures to about 70°C. Up to 50 per cent of this heat can be recycled by slurry‐to‐slurry heat excange. However conventional equipment relying on conduction has proved inadequate in this duty owing to problems of solids settling. The evaporator/condenser exchanger is more appropriate. Its thermodynamics are explained and design equations developed.
Absorption of sulfur dioxide into limestone slurry in a stirred tank
Authors: Uchida S. , Ariga O.
Published: March 2009

The absorption rate of sulfur dioxide into limestone slurries has been observed under various experimental conditions, using a stirred tank absorber which had a plane surface. The effects of the interfacial concentration of SO2, the slurry concentration, the concentration of SO2−2 ion, and the limestone particle size on the rate have been examined.

Taking the effect of SO2−2 ion on the rate into consideration, a mathematical model for SO2absorption into limestone slurries based on the film concept has been developed. The model can explain the mechanism of SO2 absorption into limestone slurries.
Modelling of non‐stationary ammonia synthesis kinetics over an iron catalyst: I. Deriving a model and estimating parameters from transient response data
Authors: Hudgins R. R. , Silveston P. L. , Chengyve Li
Published: March 2009

The transient reaction kinetic models of ammonia synthesis in a Berty reactor are identified and the parameters in the models are estimated from their transient responses. The basic model is founded on widely held views concerning the mechanism of ammonia formation on iron catalyst. The results obtained in this study show that a two‐site, dissociative adsorption model is acceptable while a competitive adsorption model is not.
Modelling of non‐stationary ammonia synthesis kinetics over an iron catalyst II. Modelling results of forced feed composition in periodic operation and for step‐changes
Authors: Hudgins R. R. , Silveston P. L. , Chengyue Li
Published: March 2009

Simulation using the two‐site dissociative adsorption model given in Part 1 of this study fails to predict the improvement observed in the time‐average rate under cyclic operation even though it does recreate the observed steady‐state and transient response features following a step‐change in the feed composition. The improvement in the time‐average cycling rate is probably due to the diffusion of nitrogen into the bulk‐phase of the iron catalyst, which is a metastable nitrogen? Iron system under forced feed composition cycling. A two‐site adsorption model, modified to take account of the inventory of nitrogen in the bulk‐phase of the iron catalyst, is presented. This model predicts the improvements in ammonia production observed under periodic operation.
Particle entrainment by axisymmetric jets
Authors: Subramanian Vishwanath , Venkatram Srinivas
Published: March 2009

The presence of particles can enhance or reduce the entrainment of an axisymmetric air jet. Measurements of particle entrainment in the 2 phase preheated jet were made by the Ricou and Spalding (1961) technique, and the results compared with theoretical estimates. Heating the jet stream improves the entrainment.
Esterification de l'acide dichloro 2.4 phenoxyacetique role et interet des resines echangeuses d'ions
Authors: Luna M. Hernandez , Alcaraz J. , Gilot B. , Jayles C.
Published: March 2009

The esterification of the dichloro 2,4 phenoxy‐acetic acid occurs slowly without any catalyst. The reaction is of order 2 or 1, with respect to the acid or acohol, respectively.

In the presence of an acid catalyst (acid toluene sulphonate —ion‐exchange resin), the reaction is quicker; it is of order 1 with respect to the organic acid and I with respect to the alcohol. The variation of the velocity constant recalls to mind that the mechanism is more complex, in spite of the simple representation.

The ion‐exchange resins play an interesting role, because they enable to avoid a separation and they are not corrosive. It is shown, however, that the penetration into the resin is limited, even when a macroporous resin is used.
A loop three‐phase fluidized bed reactor
Authors: Herskowitz Mordechay , Merchuk Jose C.
Published: March 2009

An airlift three‐phase reactor in which solid particles are fluidized in the riser by the recirculating liquid was developed. Three particle types of 1.7–8.6 mm in diam., porous and nonporous, spheres and cylinders, were studied in the water–air system. Little effect of the alumina porous particles (apparent density 1.47 × 103 kg/m3) on the gas holdup and liquid superficial velocity was found. On the other hand, the heavier, nonporous ceramic particles (density 2.4 × 103 kg/m3) had a significant effect on both design parameters. The axial distribution of particles was also a function of the particle density and liquid superficial velocity.
Mechanistic consideration of paraffin, olefin and alcohol distributions in FT synthesis
Authors: Wojciechowski B. W.
Published: March 2009

It is shown that by assuming all chain growth in the Fischer Tropsch synthesis takes place on identical sites and that the various paraffins, olefins and alcohols produced are simply the consequence of different modes of termination, product distributions which agree with experimental observations are generated. In particular the reason for the “break” in paraffin distributions is seen to be the fact that paraffins can be formed by a termination involving either the addition of a hydrogen atom or of a CH3 to the growing chain. Since there is no comparable duality in the mode of olefin formation, olefin distributions do not show a break.
New model to calculate the choking velocity of monosize and multisize solids in vertical pneumatic transport lines
Authors: Briens C. L. , Bergougnou M. A.
Published: March 2009

The choking velocity is the minimum gas velocity required for the vertical dilute phase transport of a given solids flux. Experimental choking velocities obtained from the literature for both monosize and multisize particles were compared to choking velocities predicted with various published correlations. For monosize particles, Yang's correlation (1983) gave the most accurate predictions. For multisize particles, all the literature correlations gave rather poor predictions. Much more accurate predictions were obtained with a new simple physical model which assumes that an annulus forms along the pipe wall at low gas velocities. Choking then occurs when this annulus occupies approximately 25% of the total pipe cross‐sectional area.
Approche hydrodynamique d'une réaction de pulvérisation chimique
Authors: Leseur Ph. , Morancho R. , Constant G.
Published: March 2009

Les exemples d'utilisation des aérosols générés par voie pneumatique ou ultrasonique dans l'élaboration de couches minces de composés divers (oxydes, semi‐conducteurs etc.) sur des substrats variés sont nombreux. Cependant, si les auteurs rapportent des résultats sur la composition chimique et les propriétés physiques des revêtements, ils ne font pas état d'études sur les conditions hydrodynamiques de l'écoulement de l'aérosol. Le travail présenté ici a pour but de montrer l'importance de ce paramètre et d'en faire ressortir les incidences sur la composition, la morphologie et les propriétés des couches.
Application of factor method for minimum reflux: Multiple feed distillation columns
Authors: Chou San‐Min , Yaws Carl L. , Cheng Jeng‐Shia
Published: March 2009

Analytical equations for determining the minimum reflux ratio of multiple feed distillation columns are presented by using a factor method. For the method, a factor which converts feed flow to minimum reflux ratio is used. The factor is a function of the feed concentration and thermal condition. The calculation steps for determining minimum reflux ratio of multiple feed columns are summarized. A computer program is available (microcomputer or mainframe). Application of the factor method for minimum reflux ratio is illustrated by several examples.
Rate and selectivity modification in fischer—tropsch synthesis over charcoal supported molybdenum by forced concentration cycling
Authors: Dun Jo‐Wei , Gulari Erdogan
Published: March 2009

Forced concentration cycling of the feed between pure CO and pure H2 was used to successfully change both the selectivities and reactivities of promoted and unpromoted charcoal supported molybdenum catalysts in Fischer‐Tropsch synthesis. It was found that with the unpromoted catalyst the rate enhancement increases with temperature and selectivity shifts towards methane. At the lower temperatures concentration cycling increases selectivity to ethane and higher hydrocarbons to levels only achievable with promoted catalysts. Periodic operation with the potassium promoted catalyst results in small rate enhancements but the olefin to paraffin ratio is dramatically changed without changing the carbon number distribution.
Catalytic conversion of canola oil to fuels and chemical feedstocks Part I. Effect of process conditions on the performance of HZSM‐5 catalyst
Authors: Prasad Y. S. , Bakhshi N. N. , Mathews J. F. , Eager R. L.
Published: March 2009

The conversion of canola oil to hydrocarbons using a shape selective zeolite catalyst is reported in this work. Canola oil was passed over HZSM‐5 catalyst in a fixed bed micro‐reactor and the effects of reaction temperature and oil space velocity on the conversion and selectivity were studied using a statistical experimental design. The results show that 60–95 wt% of the canola oil can be converted to hydrocarbons in the gasoline boiling range, light gases and water. The gasoline fraction contained 60–70 wt% of aromatic hydrocarbons and the gases were mostly C3 and C4 paraffins. Furthermore, the spent catalyst could be regenerated completely at 600°C in 1 h with dry air.
Black liquor gasification
Authors: Kohl Arthur L.
Published: March 2009

A new process has been developed for converting concentrated Kraft mill black liquor into clean fuel gas and reduced smelt. Bench‐ and pilot‐scale tests have demonstrated that the process can be operated to provide essentially complete conversion of the black liquor feed into fuel gas with a heating value of about 4470 kJ/m3 (120 Btu/scf) and smelt that is over 95% reduced to sulfide. Engineering studies indicate that the process can be used to fuel a gas turbine in a power generation system that integrates well with the requirements of a pulp mill. The overall process has the potential for higher efficiency, lower cost, and greater safety than conventional Tomlinson recovery boiler systems.
Effects of catalyst surface heterogeneity on methanation kinetics
Authors: Wojciechowski B. W. , Hsu C. C. , Rudzinski W.
Published: March 2009

The kinetics of methanation are presented from the point of view of reactions on heteroenergetic catalyst surfaces.

Using a general adsorption isotherm for such surfaces developed by Crickmore and Wojciechowski, we have derived kinetic rate expressions which describe the rapid drop in activity observed by Dalmon and Martin at low pressures as well as the form of the rate expression proposed by Bell at higher pressures.
A new spouting regime in beds of coarse particles deeper than the maximum spoutable height
Authors: Littman H. , Morgan M. H.
Published: March 2009

A new spouting regime for coarse particles in beds deeper than the maximum spoutable height has been identified and its location on a phase diagram is presented for an air spouted bed of 5 mm glass spheres.

The periodic formation and breakup of single bubbles originating at the top of the spout at lower gas velocities than required to observe the new regime has been studied using high speed photographs. An analogy is drawn between these observations and the breakup of bubbles in a turbulently fluidized bed.
Design and Biological Evaluation of Novel, Balanced Dual PPARα/γ Agonists
Authors: Grether Uwe , Bénardeau Agnes , Benz Jörg , Binggeli Alfred , Blum Denise , Hilpert Hans , Kuhn Bernd , Märki Hans Peter , Meyer Markus , Mohr Peter , Püntener Kurt , Raab Susanne , Ruf Armin , Schlatter Daniel
Published: March 2009

An X‐ray‐guided design approach led to the identification of a novel, balanced class of α‐ethoxy‐phenylpropionic acid‐derived dual PPARα/γ agonists. The series shows a wide range of PPARα/γ ratios within a rather narrow structural space. Advanced compounds possess favorable physicochemical and pharmacokinetic profiles and show a high efficacy in T2D and dyslipidemia animal models.

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Tuning the Rates of Long‐Range Charge Transfer across Phenylene Wires
Authors: Walther Mathieu E. , Wenger Oliver S.
Published: March 2009

Walking a tight wire: Phototriggered charge transfer across a tetra‐p‐dimethoxybenzene bridge is three orders of magnitude faster than that across a structurally similar tetra‐p‐xylene spacer, despite equal reaction driving forces in both cases (see picture). This result is interpreted in terms of markedly different donor–bridge energy gaps.

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Summary of ‘Short‐course versus long‐course antibiotic therapy for non‐severe community‐acquired pneumonia in children aged 2 months to 59 months’, including tables of key findings and quality of included trials
Authors: Haider B. A. , Saeed M. A. , Bhutta Z. A.
Published: March 2009

This is a summary, including tables of key findings and quality of included trials of a Cochrane review, published in this issue of EBCH, first published as: Haider BA, Saeed MA, Bhutta ZA. Short‐course versus long‐course antibiotic therapy for non‐severe community‐acquired pneumonia in children aged 2 months to 59 months. Cochrane Database of Systematic Reviews 2008, Issue 2. Art No.: CD005976. DOI: 10.1002/14651858.CD005976.pub2.

Further information for this Cochrane review is available in this issue of EBCH in the accompanying Commentary. Copyright © 2009 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd. The Cochrane Collaboration
Cochrane review: Modes of administration of antibiotics for symptomatic severe urinary tract infections
Authors: Pohl Annette
Published: March 2009

Background

Urinary tract infection (UTI), worldwide, is a major source of disease in children and adults. As it may have long‐term consequences such as kidney failure and hypertension, it is important to treat patients with UTI adequately. Although standard management of severe UTI usually means intravenous (IV) therapy, at least initially, there are studies showing that oral therapy may also be effective.

Objectives

To assess whether the mode of administration of antibiotic therapy for severe UTI has an effect on cure rate, reinfection rate and kidney scarring.

Search strategy

The Cochrane Renal Group's specialised register, the Cochrane Central Register of Controlled Trials (CENTRAL, in The Cochrane Library), MEDLINE and EMBASE were searched. No language restriction was applied. Reference lists of relevant articles and reviews were checked for additional studies and authors of relevant articles/abstracts were contacted for further information.

Selection criteria

All randomised controlled trials (RCTs) comparing different modes of antibiotic application for patients with severe UTI (children and adults) were considered.

Data collection and analysis

Study quality was assessed and data extracted. Statistical analyses were performed using the random effects model and the results expressed as risk ratio (RR) for dichotomous outcomes or mean difference (MD) for continuous data with 95% confidence intervals (CI).

Main results

Fifteen RCTs (1743 patients) were included. Studies compared oral versus parenteral treatment (1), oral versus switch treatment (initial intravenous (IV) or intramuscular (IM) therapy followed by oral therapy) (5), switch versus parenteral treatment (6) and single dose parenteral followed by oral therapy versus oral (1) or switch therapy (3). There was a variety of short‐term and long‐term outcomes, but no pooled outcomes showed significant differences. Most included studies were small though and there were few outcomes for combination in a meta‐analysis.

Authors' conclusions

There is no evidence suggesting that oral antibiotic therapy is less effective for treatment of severe UTI than parenteral or initial parenteral therapy. The results of this review suggest that the mode of application does not determine therapeutic success.

Plain language summary

No evidence that oral antibiotic therapy is less effective for treating urinary tract infection than intravenous antibiotics

Severe urinary tract infection (UTI) is a common infection in adults and children, causing acute disease with a variety of symptoms such as fever and flank pain. This may lead to kidney damage, kidney failure or hypertension. Standard therapy involves antibiotics given at least initially by injection. This review identified 15 studies (1743 participants). The results of this review suggest oral therapy is equally effective in treating UTI and preventing long‐term damage. This might reduce costs but also inconvenience for the patient.
The German National Innovation Programme Hydrogen and Fuel Cell Technology
Authors: Garche J. , Bonhoff K. , Ehret O. , Tillmetz W.
Published: March 2009

To support the market introduction of fuel cells and hydrogen for energetic use in Germany, the National Innovation Programme Hydrogen and Fuel Cell Technology was set up in 2006. The German Federal Government together with representatives from research organisations as well as from various industry sectors were involved in designing the programme. Combined funds from the public and private sectors amount to Euro 1.4 billion and cover the period 2007–2016. About one‐third of this total is to fund R&D and two‐third to finance demonstration and market preparation projects. The National Organization Hydrogen and Fuel Cell Technology manages the implementation in close collaboration with its partner organisation Project Management Organization Jülich, and in continuous consultation with the key stakeholders. This article spells out the main characteristics of the Innovation Programme and the organisations involved.
Effects of the Permian–Triassic boundary on reservoir characteristics of the South Pars gas field, Persian Gulf
Authors: Rahimpour‐Bonab Hossain , Asadi‐Eskandar Ashkan , Sonei Roshanak
Published: March 2009

The Permian–Triassic boundary (PTB) is a world‐wide event characterized by the most extensive mass extinction in the history of life. In the Persian Gulf, the rock record of this time interval host one of the most important hydrocarbon reserves in the world: the South Pars Gas Field and its southern extension, the North Dome (or North Field). These carbonate and evaporite successions were sampled in eight wells for petrographic, geochemical and porosity–permeability studies. An important characteristic of the Dalan and Kangan formations is the centimetre‐scale lithological heterogeneities caused by facies changes and diagenetic imprints that led to the compartmentalization of these reservoirs. These Permian–Triassic (P‐T) sediments were deposited in a shallow marine homoclinal ramp. The PTB in this hydrocarbon field is represented by a reworked coarse‐grained intraclastic/bioclastic grainstone facies deposited during a marine transgression. Prolonged subaerial exposure in the P‐T transition caused hypersaline and meteoric diagenesis, including extensive cementation, dolomitization and some dissolution, influencing reservoir characteristics of bordering units. Both δ18O and δ13C values in this succession mirror worldwide excursions typical of other P‐T sections, with some variations due to diagenetic alterations. A pronounced decline in 87Sr/86Sr values, reflective of global seawater geochemistry for most of the Permian is evident in our data. Reservoir quality declines through the late Permian, as a result of facies change and diagenesis. The Late Permian is succeeded by a Triassic transgressive facies and decline in reservoir quality. Copyright © 2009 John Wiley & Sons, Ltd.
A comparison of psychiatric consultation between geriatric and non‐geriatric medical inpatients
Authors: Schellhorn Sarah E. , Barnhill John W. , Raiteri Valentine , Faso Veronica Lo , Ferrando Stephen J.
Published: March 2009

Objective

The authors examine changes in psychiatric referral patterns for geriatric inpatients since last reported in the United States, more than 20 years ago, and compare geriatric psychiatric referrals to those of a non‐geriatric cohort.

Method

Retrospective study comparing psychiatric diagnosis, treatment and aftercare of younger (ages 18–60 years, n = 474) and older (>60 years, n = 487) patients seen in psychiatric consultation in a large, urban, university‐based tertiary care hospital setting.

Results

Compared to previous reports in the literature, this cohort contains a notably higher percentage of the ‘old‐old’ (>80 years), reflecting the general aging of those who are hospitalized. Compared to younger patients, geriatric inpatients were more commonly referred for psychiatric consultation, but overall rates of referral remain low (<4%). Geriatric patients were diagnosed with dementia and delirium more frequently; with substance dependence less frequently; and were just as likely to be diagnosed with depression. Geriatric patients were also more likely to receive atypical antipsychotic medications and less likely to receive benzodiazepines than younger patients. In patients diagnosed with depression, psychiatric follow‐up is more likely relegated to outpatient geriatricians and nursing homes.

Conclusions

Consulting psychiatrists frequently encounter geriatric patients and, given patterns of diagnosis and aftercare, should play a major role in medical staff education and in development of enhanced in‐hospital and aftercare services, including psychiatric liaison. Copyright © 2009 John Wiley & Sons, Ltd.