bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exploratory studies on batch and continuous foam separation
Authors: Grieves R. B. , Kelman S. , Obermann W. R. , Wood R. K. 
Published: February 2011

AbstractFoam fractionation has been employed for inorganic and organic chemical separations, for the treatment of radioactive wastes, and as a tertiary treatment method for secondary sewage effluents. Although the general effect of the basic variables of foam separation has been established, a quantitative approach to the process has not been made. In this study, a fundamental analysis of foam separation as a mass transfer operation is presented, utilizing both equilibrium and rate concepts of mass transfer.Foam separations have been carried out employing aqueous solutions of dodecyl sodium sulphate and alkyl benzene sulphonate at concentrations ranging from 0.005 to 0.14% weight. The range of surfactant concentrations which can be handled under a given set of operating conditions is established. In the batch experiments, volumes and concentrations of the foam and residual bulk phases are presented for nitrogen rates of 200 and 320 cc./min. Flow experiments were carried out using gas rates of 320, 440 and 580 cc./min. and liquid feed rates of about 70 and 100 cc./min. In general, the concentration of the drain stream was relatively insensitive to both gas and feed rates, but the total removal rate was found to be a strong function of gas rate.
Coefficient of thermal expansion: Reduced state correlation for water in the gaseous and liquid states
Authors: De WITT K. J. , Thodos George 
Published: February 2011

AbstractA reduced state correlation for the coefficient of thermal expansion of water has been developed from PVT data available in the literature for the substance. The coefficient of thermal expansion was expressed in terms of reduced variables and a reduced state density correlation was developed for water. This density correlation was then utilized to develop plots of the dimensionless variable, βTc, againstTRandPafor reduced temperatures up toTR= 3.0 and reduced pressures up toPR= 20.
Some physical and chemical properties of sprayed silver alloy catalysts
Authors: Osberg G. L. , Tweddle A. , Brennan W. C. 
Published: February 2011

AbstractSpraying of silver alloy catalysts by powder flame spray and by molten alloy spray techniques is briefly described. Some of the physical properties such as density, porosity, thermal conductivity and diffusibility are listed for catalysts prepared from 8.5% calcium in silver alloy, as well as a few data on pure silver, copper and nickel. Initial rate data from the oxidation of ethylene have been compiled to show a diffusion effect within the catalyst layer, and these data have been used to calculate a diffusibility factor which is lower than a similar factor estimated from oxygen‐helium diffusion experiments. The kinetic data were obtained from catalyst strips immersed in an inert mullite powder bed fluidized with reacting air‐ethylene mixture. Heat transfer coefficients from strip to bed were estimated from the kinetic data, exothermic heats of reaction and recorded temperature differences.
Yield studies in packed tubular reactors: Part 1 ‐ Mathematical model for design and analysis
Authors: Mickley H. S. , Letts K. W. M. 
Published: February 2011

AbstractThe prediction of chemical yield and productivity for packed tubular reactors is examined in two articles. A mathematical model and digital computing scheme are presented for reactors with several reactions, large heat effects, and heat exchange at the wall. Case studies show that yield loss depends strongly on the dimensions and flow rate adopted in reactor design.Part 1 presents a steady state reactor model based on material and energy balances formulated in partial differential equations on radial and axial space coordinates. The model allows for multiple reactions with arbitrary rate expressions and stoichiometry, axial bulk flow, radial effective diffusion and conduction, and a heat transfer resistance at the wall. Problems of scale‐up and similitude are discussed in terms of the model.Part 2 presents the numerical computing scheme and case studies.*
Yield studies in packed tubular reactors: Part 2 ‐ results of computed cases
Authors: Mickley H. S. , Letts R. W. M. 
Published: February 2011

AbstractPart 2, of two articles, outlines a finite‐difference computing scheme for the reactor model of Part 1, based on implicit backward differences for linear terms and explicit evaluation of non‐linear terms. The chemical system, vAA → B → vCC, with B the desired product, is examined through case studies to find sources of chemical yield loss. The system is gas phase, with exothermic reactions and Arrhenius temperature activation.Under moderate reaction conditions: 1. Activation energy differences cause yield losses of 4–8%. 2. Radial mixing causes yield losses up to 6%. 3. Failure to withdraw the stream where local yields are maximum causes yield losses larger than 1%.A technique for reactor design by simulation is outlined.
Reciprocating flow fixed bed contactor: Part 1 ‐ development, ion exchange
Authors: Spinner I. H. , Hunter R. F. 
Published: February 2011

AbstractThe development of a new semi‐continuous method for operation of a fixed bed contactor is described. The technique, termed reciprocating flow, utilizes density differences to achieve the shunting of solutions in alternating directions through a fixed bed.One of the possible flow arrangements was investigated using a strong acid ion exchanger and the calcium/sodium system. It was found that the technique was feasible for the partial removal (80–60%) of calcium from solutions having concentrations ranging from 400 to 2000 ppm. of calcium carbonate.Regenerant consumption and water requirements compare favourably with present commercial practice. However, a small regenerant leak of 1–14 meq./l. into the solution is unavoidable. Resin bed and column heights can be made a small fraction of those presently used in commercial installations.Analyses of some of the important factors limiting efficiency indicate that highly concentrated solutions may be effectively treated by the reciprocating flow technique.
Determination of chemical kinetics for multiple reaction systems
Authors: Letts R. W. M. , Mickley H. S. 
Published: February 2011

AbstractA technique is presented for the determination of chemical kinetics of multiple reaction systems from differential reaction rate data. All rate constants, activation energies, and reaction orders of the system are simultaneously fitted to all the data, using the methods of linear and nonlinear least squares. A desk calculator is practicable for systems involving ten or fewer unknown kinetic parameters. The method is especially useful for reversible reactions, since there has been no simple technique for the joint measurement of parameters of the forward and reverse reactions. The calculation is illustrated with a numerical example.
Vapor‐liquid equilibrium data for the benzene‐cyclohexane‐2‐propanol system at 760 mm. of Hg
Authors: Nagata Isamu 
Published: February 2011

AbstractVapor‐liquid equilibrium data are presented for the binary benzene‐2‐propanol and the ternary benzene‐cyclohexane‐2‐propanol systems at 760 mm. of Hg. The equilibrium data are correlated with the van Laar and three‐suffix Margules equations and a small ternary constant was found to be necessary for the satisfactory description of the ternary data. A ternary minimum azeotrope was found to be 14.2 mole % of benzene, 47.4 mole % of cyclohexane, and 38.4 mole % of 2‐propanol at 69.1°C.
Venting of high pressure fixed‐bed catalytic reactors
Authors: Basmadjian D. 
Published: February 2011

AbstractA semi‐quanlitative analysis is presented of the pressures arising in catalyst pellets during the rapid venting of a typical high pressure fixed‐bed reactor. It is shown, for both macroporous pellets and the microporous powder particles within them, that the pressures will not exceed those of the surroundings by more than a few atmosphers. It is concluded that a rapid release of pressure may be effected without risking damage to the catalyst pellets.
Analytical solutions of the equation of heat conduction for a non‐homogeneous medium
Authors: Heaps H. S. , Srivastava R. D. 
Published: February 2011

AbstractConsideration is given to the equation of heat conduction when the parameters are functions of position. A solution is obtained in the form of an infinite series in which the first term represents the solution for homogeneous material. The further terms of the series represent correction terms caused by the departure from homogeneity. Two illustrative examples are described.
The application of a modified conditional probability computer to chemical process optimization
Authors: Tinker E. B. , Nikiforuk P. N. 
Published: February 2011

AbstractThe application of a conditional probability computer to the steady‐state optimization of a simple chemical process has been investigated. On the basis of the work of previous investigators, the memory structure of the conditional probability computer was modified in a way designed to accelerate the learning process and improve the predictive capabilities of the computer. The proposed modifications were studied by optimizing an analog simulation of a simple chemical process subjected to a variety of uncontrolled disturbances. The investigations served to delineate some of the special problems encountered in the application of a binary pattern recognition device such as the conditional probability computer to process optimization. The proposed modifications were successful in achieving significant acceleration in the learning process and improvement in predictive capabilities over that offered by a conventional conditional probability computer.
Time dependent rheology of the tetrahydrofuran‐hydrogen sulphide gas hydrate slurry
Authors: Pinder Kenneth L. 
Published: February 2011

AbstractThe tetrahydrofuran‐hydrogen sulphide hydrate slurry was shown to have a gel structure at very low concentrations and to display thixotropic or false body behavior depending on the shape of the slurry particles. The crystals were allowed to grow and readings of viscosity, particle size and particle shape were made at regular intervals during the period of growth.The observations were calculated by a new technique to give a yield value, a rate of decrease of viscosity and an equilibrium apparent viscosity. A correlation was found between the yield value, the square root of the Sauter mean diameter and the shape of the particles in the slurry.A second order‐zero order reversible reaction mechanism was found to yield an equation which fits the viscosity data for this slurry. A simplified technique for determining the constants in the equation makes it possible to predict the apparent viscosity‐time curves from a few readings taken at short time interval after initiation of shear.
On the pumping of wood chips through a four‐inch aluminum pipe‐line
Authors: Brebner Arthur 
Published: February 2011

AbstractThis paper summarizes an investigation into the behavior of a wood‐chip suspension in a 4‐inch diameter aluminum pipe, 400 feet in length, when pumped under differing flow rates and concentrations, and evaluates the modes of conveyance and the friction losses therein.The following points are brought out by the investigation.
The mode of conveyance is essentially one of a sliding bed, the depth of which is related directly to the concentration. There is little evidence of any homogeneity of flow, despite the fact that the solids conveyed have a specific gravity very close to the conveying medium, water.
The friction losses are considerably higher than those of water alone, again despite the fact that the mixture specific gravity is very close to that of water. These relatively high losses are attributed to the size, shape and interlocking properties peculiar to wood‐chips.
The wood chips are easiest to handle when they are almost fully saturated.
If suitable precautions are taken the possibilities of blockages can be minimized or completely eliminated.
A rough estimate of pumping costs indicates that conveyance by pipe‐line can be competitive with other means of over‐land transport.
Correlation of adsorption equilibria of pure gases on activated carbon
Authors: Cook W. H. , Basmadjian D. 
Published: February 2011

AbstractA novel modification of the Polanyi potential theory is proposed which allows the correlation of adsorption equilibrium data of pure gases on charcoal. The range of temperatures and pressures covered extends from values corresponding to a saturated liquid to regions well above the critical point of the gas. The method has been applied successfully to equilibrium data for CO, N2, A, CO2 and the lower aliphatic hydrocarbons on activated carbon. The possibility of extending the correlation to other adsorbents is briefly discussed.
The pipeline flow of capsules part 6 ‐ numerical analysis of some variables determining free flow
Authors: Newton R. , Redberger P. J. , Round G. F. 
Published: February 2011

AbstractFour specific factors, concerned with the geometry and frictional effects of a cylindrical capsule flowing freely in a liquid‐filled pipe in which the liquid is in laminar flow, have been investigated numerically. The factors are: axial displacement of the capsule from the concentric position, end configuration and length of capsule, deformed circular cross‐section and frictional effect between the bottom of the capsule and the inside pipe surface. The effect which axial displacement has on any dynamic variable, e.g. capsule velocity, was found to be a uniformly increasing one for up to 90% of the total possible displacement. Beyond 90% displacement the effect was relatively much more pronounced.Friction was found to decrease capsule velocity uniformly: as the friction force was increased a critical value was reached for larger capsules which resulted in a rapid decrease to zero. The effect of end shape on velocities and flow rates was found to be negligible, although there was a considerable change in flow pattern. Deformation of the capsule, i.e. deformation through a vertical cross‐section, caused little effect for 10–20% deformations, beyond which there was almost a linear increase of percentage deformation with pressure gradient required to maintain the same capsule velocity. The rate of increase itself increased with the proximity of the capsule to the pipe wall.
Drag and oscillatory motion of freely falling cylindrical particles
Authors: Marchildon E. K. , Clamen A. , Gauvin W. H. 
Published: February 2011

AbstractThe behavior of circular cylinders moving singly through water under the influence of gravity was studied with a motion picture camera over a range of particle. Reynolds number extending from 70 to 2400. The terminal velocity was determined for each particle and its drag coefficient was evaluated.At Re‐greater than 300, and in some cases as low as 80, the particle acquired a secondary motion, consisting of an angular oscillation about its mean orientation and a periodic lateral deviation from its mean path of fall. A resultant dependence of the drag coefficient on particle density was found to occur. A theoretical method of predicting the period of particle oscillation was developed from consideration of variations in the location of the front‐surface centre of pressure.
An experimental study of mixing and segregation in a stirred tank reactor
Authors: Worrell G. R. , Eagleton L. C. 
Published: February 2011

AbstractThe second order, homogeneous reaction between sodium thiosulphate and hydrogen peroxide was used to study the mixing in a 2.5‐liter, continuous flow stirred tank reactor and in a 50‐gallon pilot unit. The residence time distribution was measured with deionized water and pulse injection of a tracer.At low speeds the agitation was related to a “segregation” model. The region of “maximum mixedness” and the onset of “perfect mixing” were correlated with both horsepower input and recirculation rate within the reactor.
Continuous vertical and inclined settling of model suspensions
Authors: Oliver D. R. 
Published: February 2011

AbstractAn idealized suspension of plastic spheres is used in order to demonstrate the strong effect of particle flocculation on settling velocity and solids flux. The solids flux curve for the upper region of the thickener is used to show that any layers of particles formed here should never have concentrations much greater than that of the feed. Flux curves based on batch tests give an adequate measure of the solids handling capacity of a continuous thickener.The inclination of the vessel always increases the continuous solids handling capacity. For dispersed systems the increase is greater than for flocculated systems; reasons are suggested for this effect.
Impacts of Coal Mining on the Aboveground Vegetation and Soil Quality: A Case Study of Qinxin Coal Mine in Shanxi Province, China
Authors: Donggan Guo , Zhongke Bai , Tieliang Shangguan , Hongbo Shao , Wen Qiu 
Published: February 2011

AbstractThe exploitation and utilization of coal resources have been lasting for thousands of years, resulting in a series of ecological environmental problems in China. So far, the mining area has changed into severe and typical damaged ecosystem locally and globally. The coal exploitation history is long in Shanxi province, but goafs are distributed widely. In this study, we addressed this point and took a coal mine, located in Shanxi province where the coal mining has a long exploitation history with goaf densely distributed, as an example. The growth patterns of above ground plant communities, succession characteristics of vegetation community and soil quality characters in the goafs, which could provide theoretical basis for the sustainable development of coal resources and ecological reconstruction in this region, have been studied.
Developing Pyrrole‐Derived Antimycobacterial Agents: a Rational Lead Optimization Approach
Authors: Biava Mariangela , Porretta Giulio Cesare , Poce Giovanna , Battilocchio Claudio , Alfonso Salvatore , de Logu Alessandro , Manetti Fabrizio , Botta Maurizio 
Published: February 2011

AbstractTuberculosis (TB) represents a never‐ending challenge toward which research efforts are needed. Drug resistance is the key problem that scientists in the field need to fight. The development of new drugs endowed with novel modes of action against different biological targets is of extreme importance; these new agents should also exhibit lower toxicity compared with the anti‐TB drugs currently available. Furthermore, new drugs should be inexpensive since most of the TB‐infected population lives in developing nations. In the last few years, numerous researchers have focused their attention on TB, leading to the discovery of some interesting compounds. Among these, the pyrrole‐derived compounds we developed can be considered very promising antimycobacterial agents. Aided by molecular modeling studies, we synthesized numerous compounds characterized by the same 1,5‐diarylpyrrole scaffold and elucidated very interesting antitubercular/antimycobacterial properties. Some compounds identified are extremely promising and represent a step towards the design of novel lead structures in the fight against TB. Our efforts to this end are reviewed here.
Rapid and sensitive liquid chromatography/tandem mass spectrometry method for simultaneous determination of enalapril and its major metabolite enalaprilat, in human plasma: Application to a bioequivalence study
Authors: Ghosh Chinmoy , Jain Ina , Shinde Chandrakant P. , Chakraborty Bhaswat S. 
Published: February 2011

A rapid and most sensitive method for simultaneous determination of enalapril (ENP) and its metabolite, enalaprilat (ENPT), in human plasma using ESI‐LC‐MS/MS (electrospray ionization liquid chromatography tandem mass spectrometry) positive ion multiple reactions monitoring (MRM) mode, was developed and validated. The procedure involves a simple solid‐phase extraction (SPE) followed by evaporation of the sample. Chromatographic separation was carried out on a Hypurity C18 column (50 mm × 4.6 mm, 5 µm) with an isocratic mobile phase and a total run time of 2.0 min only. The MRM of ENP and ENPT is 377.10 → 234.20 and 349.20 → 206.10 respectively. The standard calibration curves showed excellent linearity within the range of 0.064 to 431.806 ng/mL for ENA and 0.064 to 431.720 ng/mL for ENPT (r ≥ 0.990). This is the only method which can quantitate upto 0.064 ng/mL for both ENP and ENPT in a single run with the shortest analysis time. In matrix effect experiment, this method shows a % CV (% coefficients of variation) of less than 5, which means that the proposed method is free from any kind of irregular ionization process.This method was successfully applied to a pharmacokinetic study after oral administration of enalapril maleate 20 mg tablet in Indian healthy male volunteers. Copyright © 2011 John Wiley & Sons, Ltd.
Local Structure in Americium and Californium Hexacyanoferrates – Comparison with Their Lanthanide Analogues
Authors: Dupouy Gaelle , Bonhoure Isabelle , Conradson Steven D. , Dumas Thomas , Hennig Christoph , Le Naour Claire , Moisy Philippe , Petit Sébastien , Scheinost Andreas C. , Simoni Eric , Den Auwer Christophe 
Published: February 2011

AbstractMetal hexacyanoferrates are well known molecular solids for a large variety of cations, although very little has been described for actinide adducts. Two new members of actinide(III) hexacyanoferrates were synthesized with the cations americium and californium. They were structurally characterized by infrared and X‐ray absorption spectroscopy. Combined EXAFS data at the iron K edge and actinide L3 edge provide evidence for a three‐dimensional model for these two new compounds. Structural data in terms of bond lengths were compared to those reported for the parent lanthanide(III) compounds, neodymium and gadolinium hexacyanoferrates, respectively: the americium compound with KNdIIIFeII(CN)6·4H2O and the californium compound with KGdIIIFeII(CN)6·3.5H2O and KGdIIIFeII(CN)6·3H2O. This comparison between actinide and lanthanide homologues has been carried out on the basis of ionic radii considerations. The americium and neodymium environments appear to be very similar and are arranged in a tricapped trigonal prism polyhedron of coordination number 9 (CN: 9), in which the americium atom is bonded to six nitrogen atoms and to three water molecules. For the californium adduct, a similar comparison and bond length and angle values derived fromEXAFS studies suggest that the californium cation sits in a bicapped trigonal prism (CN: 8) as in KGdIIIFeII(CN)6·3H2O. This arrangement differs from that in the structure of KGdIIIFeII(CN)6·3.5H2O, in which the gadolinium atom is surrounded by 9 atoms. This is one of the rare pieces of information revealed by EXAFS spectroscopy for americium and californium in comparison to lanthanide atoms in molecular solid compounds. A discussion on the decrease in bond length and coordination number from americium to californium is also provided, on the basis of crystallographic results reported in the literature for actinide(III) and lanthanide(III) hydrate series.