bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dual Gas Flow Chromatographic Method for the Determination of Surface area and pore distribution of porous particles
Authors: Yan Ji‐min , Zhang Qi‐yuan 
Published: May 2005

AbstractA dual gas flow chromatographic method is proposed. In this method, two different gas streams are introduced separately, one as the carrier gas and the other as the gas for creating the adsorption equilibrium. The thermodesorbed absorbate is eluted by a pure carrier gas. The complete curve of adsorption isotherm can be determined easily; therefore, both the specific area and the pore size distribution can be obtained at ordinary pressure. In addition, this method can be easily changed into the continuous flow method given by Nelsen and Eggertsen [1]. The relationship among R (rate) ‐ V (volume) ‐ A (area) ‐ α (ratio) in elution chromatography are investigated, and the volume of desorbed gas can be obtained from Vd = KRAd directly with K = (αV)/(RA). The standardization for peak area is simplified and more convenient for the treatment by a microcomputer. Some results of specific surface area and pore size distribution by this method, and their comparison with those from other methods are given altogether, and the coincidence is good.
Investigations into Coulter Sizing of Biological Particles; Theoretical Background and Instrumental Improvements
Authors: Kachel Volker 
Published: May 2005

AbstractThe electric resistance pulse or electric sens Xing zone method, primarily invented by W. H. Coulter, is well suited for volume measurements of biological cells and other particles.This review summarizes the methodological investigations at the Max‐Planck‐Institut für Biochemie into the Coulter method, particularly for measuring biological cells.The distribution of the electric field in Coulter orifices was measured in enlarged model orifices and, additionally, calculated by computer programs. It is shown that the local resistance pulse height depends on the square of the local electrical field‐strength and that the particle path in the orifice influences the measured pulse heights and the orientation and deformation of particles.A new transducer system is explained which uses hydrodynamic focusing and allows short time kinetic measurements. It is equipped with a calibrator system which serves also as general control unit.
Surface Analysis of Pulverised Fuel Ash by Secondary Ion Mass Spectrometry and X‐ray Photoelectron Spectroscopy
Authors: Allen Geoffrey C. , Warner Anthony G. , Jones Allan R. 
Published: May 2005

AbstractSamples of pulverised fuel ash (PFA) obtained both from power stations and from laboratory combustion experiments have been examined by SIMS (secondary ion mass spectrometry) and XPS (x‐ray photo‐electron spectroscopy).The elemental analysis is at present semi‐quantitative and indicates presence of sulphur mainly as sulphate ion in the outer surface layer (5–10 nm) of some samples. Other elements, notably Mg, Fe, K and Ti appear at higher concentrations, up to ∼ 10% once the outer 10–20 nm surface layers have been removed by ion etching.
Electromagnetic Imaging Using Mutual Inductance Tomography: Potential for process applications
Authors: Peyton Anthony J. , Yu Zhi Zhong , Al‐Zeibak Said , Saunders Neville H. , Borges Antonio Rui 
Published: May 2005

AbstractAn overview of Electro‐Magnetic Tomography (EMT) using mutual inductance measurements is presented. The paper reviews the technique and principle of operation and gives a description of three case studies, which cover some of the generic design considerations and which illustrate the potential variety for inductive EMT systems. Results from the systems are described. These systems are presently experimental and possible future developments and applications are discussed.
Three‐Dimensional Reconstruction of Temperature and Velocity Fields in a Furnace
Authors: Schwarz Alexander 
Published: May 2005

AbstractIn this paper a reconstruction method is presented, which allows the calculation of three‐dimensional temperature and velocity fields in an industrial furnace by measuring the propagation times of sound waves. Transceiver systems working in a coal fired power station and reconstructing two‐dimensional fields are well known. Referring to these real conditions, the idea was to use two measurement planes situated over each other and projecting the fields in the volume between them. Some simulations show that weak inhomogeneous fields can be well reconstructed, whereas in the presence of turbulent flow and noise a reconstruction is critical.
Diameter Distribution of Spherical Primary Grains in the boolean model from small‐angle scattering
Authors: Gille Wilfried 
Published: May 2005

AbstractA method for determining the size‐distribution density of small spheres which are arranged, without any interaction between them, at random positions in space and form an isotropic twophase system is presented. In the case of higher volume fractions, frequent overlapping between the spheres is a logical consequence. This effect is an essential feature of the model itself and is well considered and observed. Stereological information, which contains all the necessary data about the unknown size distribution, is obtained from the angular intensity distribution (small‐angle scattering experiment) of the particle system concerned. The resulting formula still includes, in a first representation, the volume fractionpas a free parameter. In a second step, a general analytical method for the determination of the volume fractionpfrom the set covariance of the considered random closed set is derived. Therefore, the unknown diameter distribution can be obtained in every detail, starting from the scattering curve of the sample, by way of two independent working steps.
Particle Shapes Produced by Comminution in the Szego Mill
Authors: Trass Olev , Ramesh Koka V. , Papachristodoulou George 
Published: May 2005

AbstractThe shapes of particles produced by comminution in the Szego Mill, a planetary ringroller mill, in different coal grinding operations show that particle shape is dependent on the type of operation, and help explain the breakage mechanisms. Dry grinding produces particles with a low aspect ratio due to interparticle attrition; significant briquetting of fine particles may occur. In slurry grinding flaky particles are produced which are selected for breakage at rates lower than those for granular particles. Similar observations have been made with other materials. Coal‐oil‐water grinding is accompanied by the formation of coal‐oil agglomerates. Their breakage produces uniform particles with a low aspect ratio due to interparticle attrition within the agglomerates.
A Method for Increasing the Sensitivity of Phase Doppler Interferometry to seed particles in liquid spray flows
Authors: Friedman Jacob A. , Renksizbulut Metin 
Published: May 2005

AbstractA method has been developed to increase the sensitivity of phase Doppler interferometry‐based particle sizing systems to small particles in the presence of a spray containing large and small droplets; an important consideration when using seed particles to track the gas‐phase velocity in multi‐phase flows. The method, applicable to PDPA systems configured to operate in first and higher order refraction mode, involves doping the sprayed liquid with a dye that is strongly absorbing at the incident laser wavelengths. This results in greatly diminished scattered intensity from larger droplets, thus allowing the photomultiplier gain to be set to a level sufficient to easily detect small particles without saturation. Tests conducted indicate that, at a collection angle of 30° and droplet absorptivity of γ = 0.014/μm, the PDPA can accurately size absorbing droplets up to approximately 200 μm. This upper limit can be extended by changing selection angle. Tests performed with an actual spray demonstrated that the method allowed detection of 1 μm to 235 μm droplets; more than four times the instrument's usual range of 50: 1. A data correction scheme to determine the effective probe volume radius for each particle size class has been developed for absorbing particles, as standard correction schemes derived for non‐absorbing droplets excessively weigh distributions toward smaller particles.
Perimeter Exploration of Linear Chains of Circles
Authors: Surowiec Charles M. , Jones Thomas B. 
Published: May 2005

AbstractPerimeter data, obtained from structured walks performed upon straight chains of circles and displayed in Richardson plots, reveal two distinct classes of discontinuities: textural and structural. Textural discontinuities contain information about the surface features of the profile, while structural discontinuities reveal the profile's overall shape. The origins of both types of discontinuities have easy explanations. The highly predictable behavior of the structural discontinuities serves as the basis of a newly proposed method of analysis for perimeter data. The number of structural discontinuities is equal to N, the number of circles in the chain; furthermore, the value of the step size \documentclass{article}\pagestyle{empty}\begin{document}$ \underline {\lambda} $\end{document} * associated with the first structural discontinuity is inversely related to N. These properties seem is be retained when the circles slightly intersect and also when the circles vary in diameter. Analysis of the structural discontinuities may provide a new method suitable for automated examination of chain‐like agglomerate particles.
Particle Velocity Measurements in Dense Fluidized Beds
Authors: Dencs BÉLa 
Published: May 2005

AbstractThe average local velocity of the upward of particles motion was determined in a dense fluidized bed by the means of a fibre optical probe. The probe consists of two independent light gates. The particles passing in front of the light gates reflect the light, generating sign sequences that are analysed by computer. From the average time difference of the sign sequences and from the distance of the light gates, the average local velocity can be calculated. The average local velocity of the particles along the height and diameter of the fluidized bed and also as a function of the fluidization air velocity was examined. It was concluded that the average local velocity is closely correlated with the local porosity of the dense fluidized bed and depends mainly on the fluidization air velocity. Using a fibre optical probe, the optimum range of the fluidization air velocity can be determined.
The Measurement of Particles Suspended in a stirred vessel using microphotography and digital image analysis
Authors: Kramer Timothy A. , Clark Mark M. 
Published: May 2005

AbstractA novel technique to determine the size of particles suspended in a stirred vessel is investigated. The method uses microphotography to obtain a still image of the particles in situ. The equivalent circular diameter of the particles is obtained from the photographs using digital image analysis. The particles used for the test were certified particle size standards of a very small tolerance in diameter deviation. The size comparison was determined as a percent error between the measured particle diameter (equivalent circular diameter) and the diameter established by the particle manufacturer. To determine the limiting ranges of particle size and concentrations, spherical particles in a size range of approximately 1 to 10.0 μm (microns) in diameter were employed in the test. Concentrations varied from 0.00005% to 0.1% (mass basis). For each particle size, an aqueous solution of the particles was prepared at the desired concentration and placed in a stirred vessel. Photographs of the solutions were made at 25.5x, 40x, 60x and 80x magnification. For all sizes of particles, the entire range of concentration was examined.The results indicate a minimum size resolution of approximately 3μm, in a corresponding concentration range of 0.0001% to 0.05%. Similar limits on concentration were found for the larger diameter particles, although a true upper limit for the largest particle sizes was not established. The functional concentration range appears to shift towards higher mass concentrations with increasing particle size. For 2.92 μm diameter particles, the error in size measurement was found to be below 10% for a concentration range of 0.0005% to 0.05%. Additionally, a relationship between turbidity and the error was seen at low particle concentration levels where decreasing levels of turbidity generated increasing levels of error.
Generalized Lorenz‐Mie Theory for Non‐Spherical Particles with applications to phase‐Doppler anemometry
Authors: Doicu Adrian , Ebert Fritz , Schabel Samuel 
Published: May 2005

AbstractThe Scattering of focused laser beams by arbitrarily shaped dielectric bodies is investigated theoretically. The beam description is based on Davis third‐order beam approximation for the field components. The scattering problem can be solved on a spherical basis by the extended boundary condition method or by the so‐called modified version of the extended boundary condition method. For spheroidal particles with small eccentricities, a perturbation technique for the internal subproblem of the extended boundary condition method is described. This procedure is applied to analyse the influence of the particle shape and orientation on the response of a phase‐Doppler system.
On the Optical Diagnosis and Sizing of Spherical Coated and Multilayered Particles with phase‐Doppler anemometry
Authors: Onofri Fabrice , Blondel Damien , Gréhan Gérard , Gouesbet Gérard 
Published: May 2005

AbstractAfter having recalled basic theoretical results concerning the extension of generalized Lorenz‐Mie theory to the case of multilayered spheres, results connected with phase‐Doppler anemometry are considered, showing the influence of Gaussian beam intensity profiles on the light scattering properties of these particles. Particular emphasis is placed on the case of water‐coated carbon core particles, for which the possibility of obtaining simultaneous size measurements of the core and outer diameters is discussed. The sensitivity of the technique to particles with a refractive index profile is also considered, showing that this technique is more sensitive to changes in the average refractive index of the particles than to refractive index profiles, such as produced by high pressure and temperature stresses, at least for the studied geometry.
Basic Studies of Electrohydrodynamic Atomization Process using phase Doppler measurement technique
Authors: Naqwi Amir A. , Hartman Ruppert P. A. , Marijnissen Jan C. M. 
Published: May 2005

AbstractA planar phase Doppler system is used to measure submicron droplets generated by an electrospray. Measured drop dia‐meters are correlated with the liquid properties and the condition for transition of the spray from the single‐jet mode to the multi‐jet mode is introduced. In another set of measurements using a standard phase Doppler system, combined size and velocity data are employed to deduce the drag force on the drops. In a situation where the drag force is balanced primarily by the electric force, the phase Doppler measurements allow to estimate the power‐law relationship between the charge on a drop and its diameter and hence, many provide insights into the underlying atomization mechanisms.
Dual‐Mode Phase‐Doppler Anemometer
Authors: Tropea Cameron , Xu Tian‐Hua , Onofri Fabrice , Géhan Gérad , Haugen Per , Stieglmeier Manfred 
Published: May 2005

AbstractThe accurate measurement of mass flux is identified as being essential for the successful use of phase‐Doppler anemometry (PDA) in many applications, in particular with sprays. Thus measured sizes of individual droplets and the cross‐sectional area to which the flux measurement is referenced must be reliable. This paper investigates sources of measurement error in each of these quantities and provides means to eliminates or minimize these errors. A new PDA configuration, termed dual–mode PDA, is introduced as an implementation of these suggestions. Example measurements illustrate the advantages of the system over conventional arrangements.
Deformation of liquid droplets during collisions with hot walls: Experimental and Numerical Results
Authors: Karl Alexander , Anders Klaus , Rieber Martin , Frohn Arnold 
Published: May 2005

AbstractMeasurements of droplet deformation during wall impingement were performed for ethanol droplets and water droplets with diameters ranging from 100 to 200 μm. The wall temperature is well above the Leidenfrost temperature of the droplet liquid. With monodisperse droplet streams and a special illumination technique, slow motion images of the phenomena can be obtained. Measurements with high temporal resolution below 1 μs are possible using a standard video camera. The experimental results are compared with numerical results, which were obtained by solving the three‐dimensional Navier‐Stokes equations for incompressible fluids including surface tension effects. The fluids are treated with the volume‐of‐fluid method and the free surface is modeled according to the continuum‐surface‐force model. Numerical and experimental results show good agreement.
Holographic Investigations of a Diesel Jet injected into a high‐pressure test chamber
Authors: Schaller Johannes K. , Stojanoff Christo G. 
Published: May 2005

AbstractA Diesel spray injected into a high‐pressure test chamber was investigated with two different holographic techniques. The usual off‐axis recording geometry was used to investigate the very early beginning of the injection. Double pulsing of the recording laser facilitated velocity measurements. By using two different reference angles for the two recording the two images can be separated upon reconstruction of the holograms. Thus superior image quality could be achieved. Processes leading to jet formation could be identified: the spray tip is periodically axially decelerated and radially accelerated. Consequently, liquid moves at the tip off axis. The spray consists of fast central region surrounded by a slower outer jet region. The outer jet region exhibits periodic droplet concentration fluctuations which are interpreted as a result of the periodic processes at the spray tip. Some high concentration regions in the outer jet region were investigated using a dark‐field holographic technique. This technique permits single droplet velocity measurements and local droplet concentration determination at extremely high droplet concentrations. The most important result of these investigations is that no correlation between the local droplet concentration and the droplet velocity could be found.
Production of Fine Particles from Melts of Metals or Highly Viscous Fluids by ultrasonic standing wave atomization
Authors: Andersen Olaf , Hansmann Stephan , Bauckhage Klaus 
Published: May 2005

AbstractUltrasonic standing wave atomization (USWA) is a new process capable of atomizing both high surface energy liquids and highly viscous liquids. Atomization is achieved through acoustic forces acting upon a liquid jet which is guided into the central pressure node of a standing wave field. Spherical metal powders with minimum mass median diameters of less than 15 μm have been produced from metal melts with surface tensions of about 0.5 N/m. Organic liquids with viscosities between 1 and 10 Pas have been atomized, yielding mass median diameters from 20 to 330 μm. The influence of different operating parameters on the mass median diameter of metal melts and highly viscous liquids was evaluated. Parameters which were varied were ambient gas pressure, vibration amplitude of the transducers, mass flow rate, density of liquid, viscosity of the liquid, surface tension and the outlet diameter. The powders and sprays were analyzed with laser diffraction particle sizers. The physical background of the atomization process is discussed and an equation for the prediction of the mass median diameter is derived.
Influence of Refractive Index on Particle Size Analysis using the turbidimetric spectrum method
Authors: Wang Nai‐ning , Wei Jin‐ming , Hong Chang‐yi , Zhang Hong‐wu 
Published: May 2005

AbstractThe light scattering technique is now widely used in particle sizing, and includes the turbidimetric spectrum method. Although it has been reported that the light scattering technique, especially the turbidimetric method, is sensitive to refractive index, quantitative studies are rare. In this work, the effects of refractive index on the turbidimetric spectrum method were comprehensively investigated and detailed results are presented.
Calculation of the Stokes and Aerodynamic Equivalent Diameters of a short reinforcing fiber
Authors: Henn Arthur R. 
Published: May 2005

AbstractA concern about all reinforcing fibers is the extent to which they are respirable. The degree of respirability of a particle is frequently estimated in terms of its aerodynamic equivalent diameter being less than a certain value (typically 3.5 to 7 μ). However, the aerodynamic equivalent diameter, like the Stokes diameter, is only defined exactly for spheres, which is far from the shape of acicular fibers. Thus, it is useful to be able to calculate, based on actual fiber diameter and aspect ratio, the effective Stokes and aerodynamic equivalent diameters of various fibers. The present paper derives simple expression for relating the two effective diameters to actual fiber dimensions.Calculated results are compared with experimental data for glass fiber and three fractions of phosphate fiber [1], which is a short, reinforcing inorganic fiber. Agreement is seen to be good. Phosphate fiber was fractionated using a sedimentation technique described in the paper. The resulting fractions were characterized by semi‐manual measurements of micrographic dimensions and compared with results obtained from particle size instruments based on sedimentation principles. Based on these results, a large weight fraction of phosphate fiber is predicted not to be respirable.
The design, synthesis, and crystallization of an alpha‐helical peptide
Authors: Eisenberg David , Wilcox William , Eshita Steven M. , Pryciak Peter M. , Ho Siew Peng , Degrado William F. 
Published: May 2005

AbstractTwelve‐ and sixteen‐residue peptides have been designed to form tetrameric alphahelical bundles. Both peptides are capable of folding into amphiphilic alpha‐helices, with leucyl residues along one face and glutamyl and lysyl residues along the opposite face. Four such amphiphilic alpha‐helices are capable of forming a noncovalently bonded tetramer. Neighboring helices run in antiparallel directions in the design, so that the complex has 222 symmetry. In the designed tetramer, the leucyl side chains interdigitate in the center in a hydrophobic interaction, and charged side chains are exposed to the solvent. The designed 12‐mer(ALPHA‐1) has been synthesized, and it forms helical aggregates in aqueous solution as judged by circular dichroic spectroscopy. It has also been crystallized and characterized by x‐ray diffraction. The crystal symmetry is compatible with (but does not prove) the design. The design can be extended to a four‐alpha‐helical bundle formed from a single polypeptide by adding three peptide linkers.
Peptide and ester synthesis in organic solvents catalyzed by seryl proteases linked to alumina
Authors: Pugnière M. , Skalli A. , Coletti‐Previero M.‐A. , Previero A. 
Published: May 2005

AbstractTrypsin and α‐chymotrypsin were immobilized to alumina‐phosphocolamine complex, activated by glutaraldehyde. The immobilized enzymes show a great stability toward organic solvents miscible or immiscible with water. In the presence of a low concentration of water, the immobilized enzymes catalyzed transesterification reactions as well as peptide synthesis. The synthesized peptides were stable toward the immobilized enzymes.