bluuebunny/crossref_metadata_2025_split huggingface dataset:
Auslegung, Betrieb und ökonomische Betrachtung chromatographischer Trennprozesse
Authors: Strube Jochen , Schmidttraub Henner , Schulte Michael 
Published: December 2004

AbstractDesign, Operation, and Economics of Chromatographic SeperationsDue to increasing demands on pure products, there is a rapid growth of interest in chromatographic techniques. Those techniques are able to separate even compounds with small differences in their physico‐chemical properties. Continuous processes, e.g. simulated moving bed (SMB) chromatography, are a new field of growing interest for the production of pure pharmaceuticals and fine chemicals. These complex procedures cannot be optimized by a strategy based on trial and error. Therefore, rigorous modeling and efficient simulation/optimization techniques have to be used. This article presents an overview showing the advantages and disadvantages of different modeling approaches in theory and in practical applications to technical chromatographic separations.
Dioxine – Eine Aufgabe für die Umwelttechnik
Authors: Köser Heinz 
Published: December 2004

AbstractDioxins – Task for Environmental Engineering Two decades of the environmental history of dioxins, i.e. of PCCDs and PCDFs, are examined, with the main emphasis being placed on developments in Germany. After a brief consideration of the important, environmentally relevant properties of dioxins, interest is focussed on the course of the Seveso incident of 1976. The environmental effects of dioxins observed in Seveso received global publicity. In the following years our knowledge of the analysis and toxicology of this group of substances greatly improved and the production of dioxins in the aromatics sector of the chemical industry was drastically reduced. In the 1980s, discussions concentrated on the formation of dioxins in waste incineration. The results obtained during this period led to the present situation in which waste incineration is no longer a significant source of dioxin emission in Germany. The greatest known source of dioxins in Germany is in the metallurgical industry. By the year 2000 this dioxin source will also have been largely eliminated.
Modellierung und effektive numerische Simulation von chromatographischen Trennprozessen im SMB‐Betrieb
Authors: Klatt Karsten‐Ulrich 
Published: December 2004

AbstractModeling and Efficient Computational Simulation of Simulated Moving Bed Chromatographic Separation Processes.Chromatographic separation processes provide a powerful tool for the separation of mixtures in which the components have different adsorption affinities, especially when high purities are required. In this area, simulated moving bed (SMB) technology is becoming an important technique for large‐scale continuous chromatographic separation processes since it provides the advantages of a continuous countercurrent operation while avoiding the technical problem of a true moving bed. Because of the complex dynamics of the process, the choice of the optimal operation parameters and the control of the process in order to keep the product specifications at any time is not straightforward. For this challenging task, a reliable dynamic model of the process is necessary which is accurate enough as well as efficient enough in order to permit its online use for model based control. The purpose of this contribution is to review the state of the art in dynamic modeling of SMB chromatographic separation processes, highlighting new trends and results in the design of computationally effective simulation models suitable for online applications.
Dislocation cell structures in melt‐grown semiconductor compound crystals
Authors: Rudolph P. 
Published: December 2004

AbstractThe phenomenon of dislocation patterning during melt growth of III‐V, II‐VI and IV‐VI semiconductor crystals is discussed. The paper is focused on the formation of cellular structures driven by the growth inherent thermo‐mechanical stress. Of particular interest is the scaling of relations between cells size, dislocation density and acting shear stress. Among the materials there are characteristic similarities but also significant variations of the cell genesis. After the related compound specifics are discussed possible measures for retardation of cell patterning during growth are demonstrated. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic X‐ray scattering and the example of the investigation ofRCu2compounds (R= rare earth)
Authors: Schneidewind A. , Kreyssig A. , Loewenhaupt M. 
Published: December 2004

AbstractFor the investigation of magnetic structures, neutron scattering is the established standard method. Much experience and experimental know‐how encourage approaching complex problems as well. On the other hand, since the beginning of the nineties the magnetic X‐ray scattering methods (MXS) have been applied as complementary tools to the magnetic neutron scattering (MNS). We present the application of different aspects of magnetic X‐ray scattering onRCu2compounds as an example of its complementary nature to neutron scattering in the investigation of magnetism and discuss particular details of the magnetic X‐ray scattering. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Small angle X‐ray transmission characterisation of nanometer‐sized Pt‐clusters in a ceramic thin film on metal substrate
Authors: Müller J. , Löthman P. , Meyer D.C. 
Published: December 2004

AbstractNanometer‐sized platinum embedded in a ceramic matrix on metal substrate was investigated by small angle X‐ray scattering (SAXS). The influence of heat treatment on cluster size was also studied with the same method. Although the sample was as thick as 0.25 mm the measurement could be carried out successfully in transmission mode with a slit‐collimation based SAXS camera and a conventional X‐ray tube. The influences of sample geometry on experimental data were corrected numerically; the algorithm used is described in detail. Assuming spherical geometry of the platinum clusters, and that the overall system is monodisperse and diluted, the characteristic radius obeys the Guinier approximation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ergänzungsprodukte für Mauerwerk
Authors: Schubert Peter 
Published: December 2004

AbstractWandbauteile im Wohnungsbau werden zu über 80 % in Mauerwerk ausgeführt. Aber auch für öffentliche Bauten, Industrie‐ und Bürobauten wird Mauerwerk angewendet. Durch die Vielzahl der verfügbaren Mauerstein‐Mauermörtel‐Kombinationen und verschiedene Wandkonstruktionen kann eine optimale Auswahl für den jeweiligen Anwendungsfall erfolgen. Zur funktionsgerechten Fertigstellung von Wandbauteilen aus Mauerwerk einschließlich der Auflagerung bzw. Anbindung von anschließenden Bauteilen sind ergänzende Bauteile bzw. Verbindungselemente erforderlich. Auch heute noch werden die notwendigen Ergänzungen in anderen Baustoffen – i. w. in Beton ausgeführt. Dies kann zu Unverträglichkeiten mit dem Baustoff Mauerwerk aber auch mit auf Mauerwerk angepaßten “Ausbaubaustoffen” – wie z. B. Innen‐ und Außenputz – führen. Werden Ringanker oder Ringbalken in Beton hergestellt, so können aus der Verformungsunverträglichkeit zu Mauerwerk schädliche Risse entstehen.Derartige Nachteile und die damit verbundenen Probleme lassen sich vermeiden, wenn die seit Jahren verfügbaren mauerwerkgerechten Ergänzungsbaustoffe bzw.‐bauteile, im Folgenden Ergänzungsprodukte genannt, angewendet werden. Diese Stoffe und Produkte sind speziell für Mauerwerkbauteile entwickelt und angepaßt worden, sind rationell einsetzbar und haben sich seit langem bewährt.Nachfolgend wird eine Übersicht über die wesentlichen derartigen Ergänzungsprodukte sowie eine daran anschließende beispielhafte Produktinformation der verschiedenen Hersteller gegeben.
Further variations of smoke density with heat flux
Authors: Edgerley P. G. , Pettett K. 
Published: December 2004

AbstractThe heat flux in the NBS smoke chamber has been varied from 1.0 to 5.0 W cm−2 in 0.5 W cm−2 steps for some fifteen natural and synthetic materials. These experiments confirm the results given in previous papers for a smaller heat flux range, namely that smoke density varies ove4r the temperature/heat flux range. The extended range studied ensured that a much higher proportion of the materials reached a heat flux at which ignition occurred. As before at this and higher heat fluxes, the experiments were repeated in the flaming mode to ensure better reproducibility. With a few exceptions the general shape of the specific optical density/heat flux plot was similar, with a steep rise to a peak and then a corresponding drop to a low value at high fluxes. At 5 W cm−2the drop had not been reached in some cases, but it is assumed to occur later by inference from earlier work on a smaller‐scale apparatus at high temperatures. Complex materials can give unusual plots during the transition from pyrolysis to combustion. This is true of certain polymers containing fire retardant when the pyrolysis of the additive can have a separate effect.
Assessment of toxic hazards of smoke: Toxicological potency and intoxication rate thresholds
Authors: Hartzell G. E. , Packham S. C. , Switzer W. G. 
Published: December 2004

AbstractSmoke toxicity test methods which determine only lethal toxicological potency under ‘worst case’ conditions do not satisfactorily address the critical issue of relative hazard, including time‐to‐escape and tenability limits resulting from the fire performance of materials under comparable conditions. Since threats to escape from a fire are largely time‐dependent, toxic insults produced by burning materials should also be considered as rate processes. Assessment of time thresholds exhibited by burning materials under test conditions to effect performance impairment (incapacitation) of an animal model would appear to be more relevant than lethal toxicological potencies in estimating probability of successful escape from fires. A model is advanced in which intoxication rate thresholds for materials are obtained using a rodent exposure test method. Concentration‐time curves, obtained from experimentally derived concentration‐time‐response surfaces, are the basis for estimating rate thresholds which are distinctively different for each material and which vary as a function of test conditions. it is this performance impairment response surface which is potentially a key to the modeling of toxic hazards of smoke in perspective with other hazards presented by fire.
Application of test results to analysis and control of fire growth hazards
Authors: Thomas P. H. 
Published: December 2004

AbstractSome examples of the application of fire tests to hazard and risk assessment and some of the problems to be encountered are described. Reference is made to theoretical studies designed to show how to obtain basic data on material properties from ignitability and flame spread tests, and recent correlations of the rate of heat release required to cause flashover are presented. Progress in predicting fire growth from theory for certain idealized conditions will increasingly condition the choice of which processes shall be the subject of tests.
The extinction of hydrocarbon flames based on the heat‐absorption processes which occur in them
Authors: Ewing Curtis T. , Hughes J. Thomas , Carhart Homer W. 
Published: December 2004

AbstractAn empirical relation has been developed which correlates and predicts the fire‐suppression effectiveness of a wide variety of gaseous, liquid and solid agents. The flame‐extinguishment model is based on the premise that extinction is dominated by heat‐absorption processes and that a flame is extinguished when sufficient heat has been removed by the extinguishant to reduce the temperature to a limit value. This limit value. This limit is the minimum temperature at which the effective rate of the combustion reactions is sufficient to maintain flamepropagation, and it depends in a predictable way on the properties of the suppressant and flame system. The heat‐balance equation describing this is derived in two stages. In the first, a preliminary equation is obtained by considering only those substances which are thermally stable and act only as heat‐capacity sinks. In the second, the equation is generalized by consideration of all endothermic reaction sinks, e.g. vaporization, dissociation and decomposition. The general equation correlates most of the extinction data found in the literature. The results suggest that for most substances the extinguishing capacity is related to heat‐extraction data found in the literature. The results suggest that for most substances the extinguishing capacity is related to heat‐extraction and that many of the effects previously attributed to chemical mechanisms may be thermodynamic in nature rather than kinetic.
Rate of heat release by oxygen consumption in an open test arrangement
Authors: Svensson I. Gunilla , Östman Birgit A.‐L. 
Published: December 2004

AbstractEquipment has been developed for measuring the rate of heat release from building materials in an open test arrangement. The method is based on an oxygen consumption technique. A vertical sample is placed under an open hood in which the combustion gases and a certain amount of air are collected. The decrease in oxygen concentration and the mass flow of the gases are measured in the exhaust duct. The rate of heat release is then calculated. The equipment has been calibrated with good agreement between input and measured effects. The total response time for the system is 10s. The method has been used for testing building materials at radiation intensities up to 5W Cm−2. It is able to distinguish between different board materials, and the repeatability is good, The paper describes the equipment, including the weighing of a burning sample and the selection of test condition. Smoke and gas analysis can be added when desirable. Some test results with building materials are also presented.
Assessment of smoke density with a helium–neon laser
Authors: Clark Ferrers R. S. 
Published: December 2004

AbstractSmoke‐obscuration of monochromatic (0.632μm) light helium‐neon lasers and of broad‐band continuum light a hot tungsten filament is reported. The effect of forward‐scattered light is evaluated for the monochromatic source, and the degree to which the Bouguer law is obeyed for a non‐monochromatic source is discussed. Practical experience with both small‐scall and fire experiments is described.
A summary of the NBS literature reviews on the chemical nature and toxicity of the pyrolysis and combustion products from seven plastics: Acrylonitrile–butadiene–styrenes (ABS), nylons, polyesters, polyethylenes, polystyrenes, poly(vinyl chlorides) and rigid polyurethane foams
Authors: Levin Barbara C. 
Published: December 2004

AbstractA series of literature reviews was undertaken by the National Bureau of Standards to examine the toxicity and chemistry of the effluents produced when seven plastics were decomposed under various thermal and atmospheric condition. These plastics are: acrylonitrile–butadiene–styrenes, nylons, polyesters, polyethylenes, polystyrenes, poly(vinyl chlorides) and rigid polyurethane foams. The English‐language literature on each of these was reviewed and published as a separate report of the National Bureau of Standards. Over 400 different thermal decomposition products, many common to more than one plastic, were identified. The toxicity of most of these individual products is products, many common to more than one plastic, were identified. The toxicity of most of these individual products is unknown and an assessment of the toxicity of the multitude of possible combinations is not feasible at this time. Therefore a variety of bioassay toxicity protocols have been used to assess the toxicity of the gaseous atmospheres generated by the thermal decomposition of these plastics. In general, these seven plastics did not produce unusually or extremely toxic pyrolysis or combustion products when compared with those of other synthetic or natural materials. In a few cases involving additives, toxic products of concern were produced.
Effects of additives on fire properties of polyethylene
Authors: Christopher A. J. 
Published: December 2004

AbstractLow‐density polyethylene, with and without an antimony–bromine synergistic fire retardant or aluminium hydroxide, was subjected to standard fire tests and to experiments which determined the smoke and harmful fumes emitted on overheating. Both additives improved most fire properties but the fire retardant increased the smoke generated by intense radiant heat. The onset of smoke, flammable gas, carbon monoxide and acids was generally delayed by the additives. The total amounts and maximum values of these volatiles were lessened. Sample weight and form affect the results of these experiments. Observations during heating show that the additives reduce spreading of the melt, thus reducing the surface area available for oxidation.
Means of escape ‐ 1988. How close are we to modelling egress from buildings in fire?
Authors: Kendik Ezel 
Published: December 2004

AbstractDuring the last twenty years a number design methods for calculating the movement of people in buildings have been developed. This presentation briefly reviews some of these modelling efforts. Furthermore, it discusses some aspects of the pedestrian movement and addresses an egress model based on the data provided by Predtechenskii and Milinski. This model is applicable to the evacuation of multi‐storey buildings via staircases and predicts the flow movement in terms of time with regard to the building's layout and the interdependencies between adjacent egress way on this model, written in GWBasic language for any IBM‐compatible personal computer. The program is built up as a dialogue between the user and the computer, where the escape route configurations (the width and the length of each section) as well as the number of the persons are put gradually during the course of the computation. The program enables the user to change the dimensions of the building's means of escape and the occupant load easily and work out the influence of the variation on the complete circulation system. Recently, the program also calculates the flow movement under decreased visibility conditions on smoke filled escape routes based on japanese measurements about the walking speed of pedestrians in fire smoke.
Defining the thermal environment in fire tests
Authors: Keltner N. R. , Moya J. L. 
Published: December 2004

AbstractThe ability of engineered systems to withstand a fire environment is usually demonstrated by test. Iterative design and experimentation historically has been used to develop these engineered systems. To optimize the engineered system, in instances where the cost of the prototype is high, the process of iterative redesign and testing may be infeasible. Consequently, in such instances it is desirable to predict the thermal performance of the engineered system analytically. In order to predict the thermal performance of the engineered system the thermal insult the test environment provides to a test unit must be quantified. To quantify the thermal insult, both temperature and heat flux measurements are necessary. However, as will be discussed, one of the major difficulties associated with conducting any type of fire test is making accurate measurements in both the fire and on the test unit. This paper discusses a number of measurement techniques. Due to the potential for errors in the measurements, the uncertainty in the measured parameters is emphasized.
Fire‐gas hazards in rail traffic
Authors: Prager F. H. , Cabos H.‐P. 
Published: December 2004

AbstractA review is given of the various national requirements and test procedures concerning testing and classification of smoke produced in the case of a fire in rolling stock. A comparison of the various test methods is made using the relevant available literature. The toxic potency philosophy of SC3 ‘Toxic Hazard in Fire’ from ISO TC92 is used to provide a concept for assessing the possible smoke hazard in the case of a fire.
The flammability of polyacrylonitrile and its copolymers III. Effect of flame retardants
Authors: Hall Michael E. , Zhang Jun , Richard Horrocks A. 
Published: December 2004

AbstractThis paper extends previously reported work 1,2 and describes the influence that a range of selected flame retardants have on the burning behaviour and pyrolyses of homo‐and copolymers of acrylonitrile. Various inorganic and organic phosphorus and nitrogen‐ or sulphur‐containing, halogen‐containing (in the absence and presence of halogen or antimony (III) oxide) and nitrogen‐containing flame retardants and red phosphorus were studied using LOI, TGA, DSC and residual char measuring techniques. Flame retardancy relates directly to char‐forming tendency for all retardants and their ability to reduce the dominance of flammable volatiles formed during the first stage of acrylic polymer pyrolysis. Ammonium phosphates are particularly effective flame retardants for the selected copolymers. Possible mechanisms of retardant activity are discussed, including the char‐forming tendency of antimony–bromine combiniations.
The use of partial least squares (PLS) in quantitative FTIR: Determination of gas concentrations in smoke gases of burning textiles
Authors: Pottel Hans 
Published: December 2004

AbstractFourier transform infrared spectroscopy ca be used for on‐line smoke gas analysis of burning textile materials for several gases simultaneously. The technique is sensitive enough for the determination of the concentrations of compounds like H2O, CO2, Co, NO, NO2, SO2, C3H4O, HCI, HBr, HCN and HF. Quantitative analysis is, however, sometimes difficult to perform due to spectral interferences of two or more components. Simple mathematical techniques based on the direct relation between concentration and peak height or peak height or peak area then becomes impossible since they cannot be completely assigned to one component. Spectral subtraction can then be used but the results are sometimes unsatisfactory. Alternative techniques, like Partial Least Squares (PLS), Provide excellent possibilities to overcome the problems due to overlapping spectral features, without making use of spectral concentrations of different compounds in smoke gases. The use of PLS as a tool to overcome the problem of interfering of different compounds in smoke gases. The use of PLS as a tool to overcome the problem of interfering components is demonstrated by application to the overlapping spectral bands of H2O/CO2 and of H2O/NO. PLS calibration curves for other interfering components can be constructed in an analogous way.
Specific processing of the bacterial β‐lactamase precursor in Saccharomyces cerevisiae
Authors: Roggenkamp Rainer , Hoppe Jürgen , Hollenberg Cornelis P. 
Published: December 2004

AbstractSynthesis and processing of the bacterial enzyme β‐lactamase (E.C. 3.5. 2.6) were studied in Saccharomyces cerevisiae. The 2‐μm DNA vector pADH040‐2 containing the yeast ADH1 promoter fused to the bacterial gene was used in order to obtain enhanced synthesis of the bacterial protein in yeast transformants. Both precursor and mature β‐lactamase were shown to be present in yeast cells, the precursor being the major product. The mature enzyme was purified about 500‐fold over crude extracts to apparent homogeneity and thus represents nearly 0.2% of the total yeast protein. No difference in specific activity and molecular weight could be observed when compared with the authentic β‐lactamase from Escherichia coli. Specificity of the processing of β‐lactamase in yeast cells was verified by partial amino acid sequence analysis demonstrating the removal of the signal peptide at the correct position.