bluuebunny/crossref_metadata_2025 huggingface dataset:
Zertifizieren von Qualitätssicherungs‐systemen
Authors: Jahn Hans , Pärsch Joachim G.
Published: December 2004

Certification of Quality Assurance Systems. Assurance of quality, working in a systematic and documented manner with the aim of contributing to constant improvement of the quality levels of a company, is now standard practice. A visible sign of quality competence is a quality assurance system certificate that is issued by a neutral certification body after assessment of the effectiveness of existing quality assurance systems. The German Society for the Certification of Quality Assurance Systems (DQS), a neutral, not‐for‐profit institution, performs such assessment in Germany on the basis of DIN ISO standards 9001, 9002, or 9003, and issues certification of quality assurance systems.
Methodik des produktionsintegrierten Umweltschutzes in der chemischen Industrie
Authors: Hassan Ali , Kostka Sebastian
Published: December 2004

Methods for Production‐Integrated Environmental Protection in the Chemical Industry. This article describes the integration of production‐integrated environmental protection in the chemical industry into strategic planning, research and development as an optimisation problem. A holistic approach is adopted to seek a compromise between contradictory economic, ecological, and other goals; these goals have to be prioritized subjectively. The ecological demands are quantified with the aid of technical factors, efficiency, and monetary factors. A methodology for decision making in production‐integrated environmental protection is demonstrated and discussed for a number of selected applications. It is based upon exact optimization with one or multiple target quantities, efficiency analysis, and quantitative models.
Definition von Destillationslinien bei der Trennung von Mehrstoffgemischen
Authors: Vogelpohl Alfons
Published: December 2004

Definition of Distillation Lines in the Separation of Multicomponent Mixtures. In recent years “distillation lines” have been used for the assessment of the separation behaviour of multicomponent mixtures, with these distillation lines being defined differently by different authors. The theory of distillation of multicomponent mixtures shows that it is appropriate to distinguish between residue lines and rectification lines. While the profile of residue lines is determined solely by the thermodynamic phase equilibrium, that of rectification lines also depends upon the mass transfer model used. By analogy with VDI Guideline 2761: “Thermal Separation Processes in Process Engineering”, it is proposed that residue lines and rectification lines are designated by the collective term distillation lines.
Verhalten feinkörniger Schüttgüter
Authors: Molerus Otto
Published: December 2004

Behaviour of Fine‐Grained Bulk Solids. The behaviour of fine‐grained bulk solids embraces such diverse phenomena as the moistening properties or thermal conductivity. Only two aspects are considered in this article, viz, the mechanics of bulk materials and the flow mechanics of fine‐grained bulk solids. The interplay of these two areas is illustrated by a detailed analysis of the various kinds of gas fluidisation.
Nichtporöse Membranen und ihre Anwendung
Authors: Cen Yanwei , Meckl Karin , Lichtenthaler Rüdiger N.
Published: December 2004

Non‐porous Membranes and their Applications. In recent years membrane systems have gained increasing industrial importance in the separation of multicomponent mixtures. This also applies to porous membranes in which the mass transfer is effected by the difference in electrochemical potential of the permeating components on the feed and permeate sides. After presenting the construction and the mode of operation of non‐porous membranes, the article considers industrial membrane processes. Special attention is focussed on development work starting from the research results obtained in the laboratory and culminating in the industrial application. The development of membranes with support‐bound „passive”︁ or „active”︁ transport, such as encountered in some biological membranes, offers interesting insights.
Formbarkeit keramischer Massen durch Extrusion
Authors: Gleißle Wolfgang , Graczyk Jan
Published: December 2004

Extrusion and Formability of Ceramic Pastes. Numerous complicated catalyst geometries are produced by extrusion of plastic ceramic materials. The demands on the precision of the forming process and the formability of the materials are extremely high. At a first glance, plastic ceramic materials seem to be concentrated solid‐liquid suspensions. Rheometric methods, in particular capillary rheometry, are especially suitable for testing of these materials. However, the flow processes occurring during extrusion are very complex, with many special effects such as slip, shear‐thinning, shear hardening, high entrance pressure loss. Viscosity functions are not material functions. However, in spite of these difficulties, capillary rheometry, when critically applied, is a most advantageous tool in the purposeful development of easily extrudable ceramic materials. Correlation of the rheometric test results with the extrusion process during the production of honeycomb geometries is presented using aluminium oxide ceramics as an example.
Umweltschutz und Sicherheit: Die Verantwortung des Ingenieurs
Authors: Lipphardt Günter
Published: December 2004

Responsibility of the Engineer for Environmental Protection and Safety. Engineers in industry are expected to focus uncompromisingly on environmental protection in their work. A demand of this kind would require the absolute truth concerning the yardstick against which the features are to be measured. However, there is no such yardstick. In addition, most alternatives are not entirely free of environmental impact. Which ones can or must the engineer's choose? Apart from technical and scientific limits, there are also economic limits within which engineers must act in order to realize new technologies. On the other hand, engineers must speak up for those areas which they consider on the basis of their knowledge and experience, to be essential to the interests of the general public and the economy. This applies not only to activities in the field of engineering, but also to personal involvement in the public sphere. This is an area that still offers considerable scope.
Neue Technologien — neue Korrosionsprobleme
Authors: Heitz Ewald
Published: December 2004

New Technologies – New Corrosion Problems. Adequate resistance of materials to corrosion is equally important for classical and for new technologies. This article considers the economic consequences of corrosion damage and, in addition to the longknown GNP orientation, presents a new approach to the estimation of the costs of corrosion and corrosion protection via maintenance and especially corrosionrelated maintenance. The significance of “high‐tech”, “medium‐tech” and “low‐tech” material and corrosion problems is assessed. Selected examples taken from new technologies in the areas of power engineering, environmental engineering, chemical engineering, and biotechnology demonstrate the great significance of the problems. It is concluded that corrosion research and corrosion prevention technology will never come to an end but will constantly face new problems. Two technologies are of particular interest since they focus attention on new methods of investigation: microelectronics and final disposal of radioactive wastes. The article closes by considering the importance of the transfer of experience and technology. Since the manufacturs and operators of machines and plant do not generally have access to the very latest knowledge, they should be kept informed through advisory services, experimental studies, databases, and further education.
Simulation des instationären hydraulischen Verhaltens verfahrenstechnischer Anlagen mit langen Rohrleitungen
Authors: Raschke Erhard , Seelinger Peter , Sperber Axel , Straßburger Rolf
Published: December 2004

Simulation of Transient Hydraulic Behaviour Process Engineering Plant with Long Pipes. A knowledge of transient flow processes is becoming increasingly important for the reliable design and control of process engineering plant. Transient flow processes occur, of example, in long liquid‐carrying pipes: on start‐up and shut‐down of plant, in emergency shut‐downs and fast closure, i.e. when liquid is rapidly decelerated or accelerated. The consequence of such an event is a hammer effect, i.e. a short, often violent change of pressure placing considerable stress on structures. Such hammer effects are readily calculated by numerical methods in single phase media. Technical devices for prevention of inadmissibly high pressures surges can also be designed by means of simulation calculations. However, hammer effects also occur by sudden condensation of vapours. A number of systems in which condensation hammer effects can occur are considered at the end of this contribution. Two special damping measures are presented.
Entwicklungsstand der Alkalichlorid‐Elektrolyse. Teil 1: Zellen, Membranen, Elektrolyte, Produkte
Authors: Bergner Dieter
Published: December 2004

State of the Art in Alkali Chloride Electrolysis (I). Cells, Membranes, Electrodes, Electrolytes, Products. The state of the art in the field of alkali chloride electrolysis for the production of chlorine, alkali hydroxide and hydrogen is characterized by the state of development of the membrane cell process. By 1996 about 230 membrane electrolysis plants with a combined NaOH capacity of about 11 million metric tons will be on line worldwide. This amounts to roughly one fourth of the world's caustic soda production by electrolysis. In this review the main membrane cell technologies, the ion exchange membranes of different suppliers and anodes and cathodes of the membrane cells are described. This first part of the review ends with a look at the problems of brine quality for the membrane cells and a description of the products chlorine, caustic soda solution and hydrogen.
Planung der Kuppelproduktion in Systemen von chemischen Mehrzweckanlagen
Authors: Jänicke Winfried
Published: December 2004

Planning of Coupled Production in Multipurpose Chemical Plant. This article considers strategies for computer‐aided planning of coupled production for systems of net worked multipurpose plant. Reasons are given for the failure of classical strategies such as are used in PPS systems. A procedure is described which, starting from a final product, automatically generates a cascade of previous product jobs and assigns them to production lines along a time axis (simultaneous material, pecursor, and production line assignment planning). Possibilities of interactive improvements of a given solution on consideration of factors such as storage costs and turnover are presented.
Chemieanlagenbau — Märkte im Osten
Authors: Jaeschke Lothar
Published: December 2004

Market for Chemical Plant in Eastern Europe. For reaching changes in the former Comecon countries have led to totally altered market structures, and these developments are continuing. The most serious problems arise from the precarious financial situation, altered and unclear decision processes, also with regard to the difficult disbanding of the state sector, and above all the totally inadequate economic legislation. Since the former Comecon countries will undoubtedly be one of tomorrow's main markets, western plant constructors must already give this market very serious attention, although it will take some considerable time until complete economic stability is reached. Collaboration with local partners is often a good way of consolidating a market presence, with a range of possibilities including cooperation, joint ventures, or purchase of a local company. Setting up one's own company is an alternative approach. Which ever route is selected, it is of greatest importance that the customer is extensively involved in all stages of completion of the order.
Abluftreinigung und Lösungsmittel‐ Rückgewinnung durch Adsorption an Adsorberharzen
Authors: Reschke Güunter , Mathews Waldemar
Published: December 2004

Cleaning of Exhaust Air and Solvent Recovery by Adsorption on Polymer Resins. In an overview the technologies of air cleaning and solvent recovery is followed by an account of the adsorption of solvents on polymer resins. Test plant, experimental adsorption equilibria and breakthrough curves as well as mathematical modelling for the design of fixed bed adsorbers are the main focus of attention. Practical examples demonstrate the advantages of using polymer resins in solvent recovery.
Chemiestandort Europa – Herausforderungen und Strategien
Authors: Bufe Uwe‐Ernst , Altwegg Markus , Schultze Wolfgang , Schadow Ernst
Published: December 2004

Europe as Location for the Chemical Industry – Challenges and Strategies. During Achema '94 visitors were invited to attend a number of panel discussions. One of these addressed the subject of Europe as a location for the chemical industry. The highly topical nature of this subject matter and the consequences for each one of us if the attractiveness of Europe for the chemical industry continues to wane were reasons enough for Chemie Ingenieur Technik to publish the main content of this discussion. Participants in the discussion were Dr. Uwe‐Ernst Bufe, Degussa AG, Frankfurt, Dr. Markus Altwegg, Hoffmann‐La Roche, Basel, Dr. Wolfgang Schultze, of the Labour Organisation IG Chemie Papier Keramik, Hannover, Dr. Ernst Schadow, Hoechst AG, Frankfurt. The discussion was mediated and chaired by Hans‐Wolfgang Pfeifer of the Frankfurter Allgemeine Zeitung Group.
Modellierung des Stoffaustausches von flüchtigen organischen Verbindungen in hochviskosen Medien
Authors: Warnecke H.‐J. , Prüss J. , Hübinger W. , Minges R.
Published: December 2004

Modelling of Mass Exchange of Volatile Organic Compounds in High‐Viscosity Media. Polymers may contain low‐molecular weight organic components as a result of incomplete reaction during polymerisation, contamination of the reactants, and undesired side reactions. Aqueous of polymers are usually applied to surfaces (emulsion paints, adhesives, paper finishing agents, etc.). Since low molecular components then escape into the air, they are removed after polymerisation by stripping the product with an inert gas. While the engineering used for this step is well developed, the mass transfer processes involved have received little yet controversial attention. This paper presents a mechanistic mathematical model which includes the mass transfer steps occurring during stripping in a stationary continuously operating apparatus with complete back‐mixing. Measurements of the position of phase equilibria and determination of the depletion achievable in an aerosol jet loop reactor demonstrate that, provided that the temperature of treatment exceeds the glass transition temperature, the stripping process is determined solely by the partition coefficients of the exchanged components between the phases, the hydrodynamic parameters, and the reactor operating conditions. This contradicts the claims of some authors that diffusion processes in the latex particles are of decisive importance.
Abscheidung aus überkritischen Gasen
Authors: Birtigh Andreas , Brunner Gerd
Published: December 2004

Precipitation from Supercritical Gases. The importance of processing substances with supercritical gases as a separation method has increased in recent years, particularly as a means of obtaining products produced without organic solvents. This article surveys the various methods of depositing substances from a supercritical phase. The surest method, i.e. that of reducing the pressure to subcritical values, involves a high energy consumption for recompression of the phase when performed on an industrial scale. For this reason, isobaric deposition methods (adsorption, absorption, membrane separation) were examined to establish their suitability for regenerating the supercritical solvent.
Einsatz eines Aerosolmassenspektrometers (AMS) zur Untersuchung von Partikelbildungsprozessen in Hochtemperaturreaktoren
Authors: Hospital Andreas , Roth Paul
Published: December 2004

Aerosole sind Zweiphasengemische bestehend aus einer Gasphase, in der in feinster Verteilung feste und/oder flüssige Partikel schweben. Sie können in unterschiedlichen Bereichen der Verfahrenstechnik entweder als unerwünschtes Abgas auftreten oder als Produkt gezielt generiert werden.
Bestimmung kinetischer Konstanten der radikalischen Polymerisation mittels adiabatischer Reaktionskalorimetrie unter Berücksichtigung der Molmassenverteilung
Authors: Mosebach Michael , Reichert Karl‐Heinz
Published: December 2004

Das beschriebene Verfahren bestimmt kinetische Daten radikalischer Polymerisationen in Lösung mittels der adiabatischen Reaktionskalorimetrie unter Berücksichtigung der resultierenden Molmassenverteilung des Endprodukts. Als Beispielreaktion dient dabei die radikalische Polymerisation von Methylmethacrylat (MMA) in Toluol mit 2,2′‐Azobis (2,4‐dimethyl‐valeronitril) (ADVN) als Initiator. Es konnte bereits gezeigt werden, daß sich aus den im adiabatischen Reaktionskalorimeter gemessenen Temperatur/Zeit‐Verläufen Bruttogeschwindigkeitskonstanten der Polymerisation von MMA ohne Geleffekt [1, 2] und mit Geleffekt [3, 4] bestimmen lassen. Bei Kenntnis eines geeigneten mathematischen Modells zur Beschreibung des Reaktionsablaufs können anhand des gemessenen Temperatur/Zeit‐Verlaufs der Polymerisation und der Molmassenverteilung des Polymers auch Werte für die Elementarreaktionen bestimmt werden.
Modellierung reaktiver Stoffaustauschprozesse
Authors: Brinkmann Manfred , Warnecke Hans‐Joachim , Prüss Jan
Published: December 2004

The design of reactive exchange processes is generally accomplished with the aid of the enhancement factor, whose calculation is frequently possible only by iterative and approximate methods. In contrast, a mathematical model linking microscopic reaction‐diffusion equations with macroscopic phase balances permits direct calculation of absorption. Complication reaction pathways and non‐linear phase equilibria can then also be considered without making simplifying assumptions. The influence of liquid phase viscosity on exchange parameters can be quantified and included in model calculations by coupling the more comprehensive film penetration theory and the theory of isotropic turbulence. Simulations not only demonstrate the influence of the system and operating parameters on absorption but also indicate the importance of the choice of excange model in systems with conversiondependent liquid phase viscosity.
Analyse und Anwendung dynamischer Optimierungsalgorithmen für Batch‐Prozesse
Authors: Li Pu , Wozny Günter
Published: December 2004

Batch processes being increasingly used in the chemical industry. The advantages of batch processes are their flexibility, high product purity and the possibility of frequent product changeover. For the economical operation of a batch process it is necessary to develop an optimal strategy; therefore a proper optimisation approach is required. For this reason two different optimisation algorithms, differential dynamic programming and a simultaneous optimisation approach, are investigated in this paper. The characteristics of the algorithms are worked out and their efficiency is analysed. Simulation results from batch reactors and a batch column demonstrate the scope of application of the algorithms.
Intervallmathematische Methoden in der Prozeßtechnik — Flexibilität und Unschärfe
Authors: Gruhn Günter , Colditz Stefan
Published: December 2004

Das Anliegen dieses Beitrags besteht darin, neuartige Vorgehensweisen der mathematischen Modellierung, Simulation und Optimierung verfahrenstechnischer Prozesse im Hinblick auf die Behandlung von Entwurfs‐ und Steuerungsproblemen vorzustellen. Diese Vorgehensweisen beruhen auf der Anwendung von Grundgedanken und Methoden der Intervallmathematik und deren Anpassung an Problemstellungen der Verfahrenstechnik.
Funktionale Kolloide: Strukturbildung und Chemie im Nanometerbereich
Authors: Antonietti Markus
Published: December 2004

Colloid chemistry is the science of the finely divided state of material. Colloids are small units of gas, a liquid, or a solid whose size is measured in nanometers. Systems containing or made up of colloids can have special properties differing significantly from those of the molecules from which the colloid particles are made and from those of the corresponding bulk material. The colloidal state is therefore sometimes described as the “fourth state of aggregation”. Fundamental properties such as melting point, conductivity, or the optical parameters depend upon particle size. Modem colloid chemistry thus provides considerable scope for the production of new materials with new combinations of properties through control of the chemical composition on a nanometer scale. These possibilities are considered in the light of a number of research projects being pursued at the Max Planck Institute for Collid and Interface Research.
Struktursynthese und Optimierung nichtidealer Rektifizierprozesse
Authors: Bauer Markus H. , Stichlmair Johann
Published: December 2004

Optimization processes with MINLP are inherently capable of dramatically reducing the effort and time required for synthesis and analysis of separation processes. This approach represents an extremely powerful tool whose use, however, requires an understanding of process engineering. The principal advantage of the method lies in the simultaneous optimization of both the structure and also the operating conditions of a process. Reliable convergence to the global optimum requires careful limitation, scaling, and prior assignment of all variables. Starting values can be obtained by thermodynamic analysis of the phase equilibrium and by an overall balancing of the individual separation steps. Heuristic reduction of the superstructure generated on the basis of the preferred separation, appears appropriate given the present status of available models and solution algorithms. Under these conditions, the outer approximation algorithm recommended for this model will find the optimum solution after just a few iteration steps.
Das Beschichten von Oberflächen
Authors: Klostermann Rainer , Mewes Dieter
Published: December 2004

The coating of different substrates is an important part of many industrial manufacturing processes. The fluids used in these processes have very different rheological properties. They are coated to solid surfaces with high substrate velocities by dipping, spraying, casting or by the use of knives, blades and rollers. The field of flow between two rotating rollers is influenced by the free surface of the fluid and the contact point between the three phases, solid roller, coating fluid, and the surrounding gas. Viscous, inertial, gravitational and capillary forces control the velocity field between the rollers. Stable fluid coatings that satisfy the increasingly stringent demands on the quality of their surface structure have to be created within certain limits of the forces occurring. In order to predict these limits, the flow fields have to be completely calculated. Therefore all three conservation equations and an additional equation for the position of the free surfaces are solved with consideration of the constitutive equations and possible wall slip effects of the coating fluids.
Basismodelle für Reaktoren — eine kritische Bilanz
Authors: Platzer Bernd
Published: December 2004

In the literature of chemical reaction engineering, the basic models for reactors are deduced in different ways. This paper demonstrates that the authors do not always stringently differentiate between fluid mechanics and chemical reaction engineering methods. Thus misinterpretations may arise. As this publication shows, it would be more precise to use instead of ideal reactors the term completely/radially mixed reactors (mixing vessel/pipe). In addition, attention is directed to convection reaction models. They give an idea of the local concentration profiles in reactors for a small mathematical effort. The models give predictions superior to those of the ideal reactor models and of the dispersion model, both of which can only give mean values.
Innovation gleich Information plus Intuition
Authors: Blass Eckhart
Published: December 2004

As a consequence of the structural crisis of German industry, politicians and business leaders are increasingly calling for new and improved products, new and better processes. Innovation is in great demand. Yet what is innovation? How do innovations happen and how can they be promoted? What kind of scientific and technical environment is needed to produce a rich crop of innovations? Good information sources can be an enormous help.
Liposomen – Strukturen und Herstellung
Authors: Nothelle Ricarda , Hamann Hans‐Jürgen
Published: December 2004

The general public has only recently become familiar with liposomes through their use in cosmetics although a wide range of applications has long been known in the scientific literature. Depending upon the pertinent application very different liposomes are required, which has led to a large number of methods for their production. This article describes the principal processes: rotor/stator dispersion, the injection method, dialysis, extrusion, and homogenisation. The most suitable methods for industrial use are rotor/stator emulsification, the injection method, extrusion, and homogenisation. Examination of commercially available liposome‐containing products shows that high‐value products such as cosmetics and pharmaceuticals predominate – commercial use of liposomes is often limited by the sophisticated production methods and expensive raw materials.
Auslegung von Zyklonabscheidern für Notentlastungssysteme
Authors: Schmidt Jürgen , Giesbrecht Hartmut
Published: December 2004

The principal dimensions of cyclone separators for emergency response systems have been optimized by determination of the gas loading capacity for geometrically similar cyclones of 290 and 1000 mm diameter. For the experiments, separators made of Plexiglas with top or bottom mounted inlet tubes, with varying feed diameters and top and exit geometries. Moreover, the properties of the liquid in the binary mixture to be removed were also changed. For scale‐up the gas volume flow density in the defiecting apron should be limited. Overall the measurements have shown that the optimized equipment is equally suited for removal of aqueous, viscous, and foaming media. The flows encountered in emergency blow‐down of reactors can therefore be reliably separated. Compared to the recommendations given in the literature, significantly smaller equipment is required for the same separation performance.
MINIPLANT‐Technik – ausgewählte Aspekte der apparativen Gestaltung
Authors: Steude Heinrich E. , Deibele Ludwig , Schröter Jürgen
Published: December 2004

Only in exceptional cases do literature data and computer programs suffice as a basis for the dimensioning of new engineering processes in the chemical industry. As a rule, the new process is constructed with all process steps on a laboratory scale and operated with original products. In doing this, use of made of MINIPLANT engineering, with each process step being performed on the smallest scale which will still permit reproducible operation. This eliminates the need for sophisticated pilot plant. This article presents MINIPLANT equipment for fluid processes such as distillation, rectification, evaporation, and liquid‐liquid extraction, for which miniaturisation is farthest advanced. In the development of smaller equipment for solids processing such as drying, crystallisation, and size reduction, further efforts will be required. In conclusion, problem solutions in the area of automation and control are also addressed.
Tomographische Meßverfahren – Visualisierung zweiphasiger Strömungsfelder
Authors: Reinecke Nicolas , Petritsch Georg , Schmitz Dirk , Mewes Dieter
Published: December 2004

Some applications of electrical tomographic techniques for the measurement of gas/liquid flows in packed columns are described. Electrical tomography is nonintrusive, of high temporal resolution, low cost, engenders no radiation hazard and is easy to implement. This mainly encourages the development of capacitance, resistance and inductance sensing techniques which are applied within volumetric fields of density, pressure, concentration, temperature, velocity or void fraction. The mentioned fields are instationary most of the time or they are of transient character. Therefore, not only temporal but also spatial resolution is required. X‐ray tomography is used for the visualisation of gas‐liquid flow inside packed columns. The measurement system consists of a fixed X‐ray tube and an array of 15 detectors. The spacial resolution is of the order of 0.4 × 0.4 mm, the temporal resolution is increased by use of only 12 steps of rotation and a filtered back‐projection algorithm.
Theorie und Praxis bei Rauchgaswäschen
Authors: Ulbrich Michael , Meckl Stefan
Published: December 2004

Practical experience acquired on operation of large scale flue gas scrubbers often fails to agree with the theoretical knowledge on which the design and operation of flue gas scrubbers are based. The absorption of SO2, HCl, and mercury reveal the additional effects to be considered for optimal design and operation of flue gas scrubbers. Mist formation, wetting of plastic packing, or the buffer effect on the absorption of concentration peaks are such additional effects. The influence of these effects on the design and operation of flue gas scrubbers is analyzed by the calculation of typical examples.
Experimentelle und theoretische Untersuchungen der Gradientenchromatographie von Proteinen
Authors: Mihlbachler Kathleen , Anspach Friedrich Birger , Seidel‐Morgenstern Andreas
Published: December 2004

Preparative liquid column chromatography is a powerful method for the isolation of proteins from complex mixtures. The use of solvent gradients has proved invaluable in the optimisation of the chromatographic separation process. In contrast to isocratic chromatography, the eluting strength of the solvent is increased during the separation. To this end, an increasing proportion of a solvent of high eluting strength is added to solvent of low eluting strength. This publication is intended to contribute to the general understanding of and to a quantitative description of preparative gradient chromatography of dissolved proteins. The analysis is based on the experimental determination of various chromatograms of the model protein lysozyme on a cation exchanger.
Abtrennung organischer Dämpfe mit Membranen
Authors: Nitsche Volker , Ohlrogge Klaus , Stürken Kai
Published: December 2004

Removal of Organic Vapours by Membranes Even on consistent use of productionoriented environmental protection measures it still proves impossible to avoid the formation of solvent‐containing gaseous effluents in many production processes. Thus the reduction of emissions by purification of solventcontaining process and exhaust gas streams is still a highly topical matter. Thermal, catalytic, or biological oxidation processes leading to destruction of the organic solvents should only be used when solvent recovery is impossible. Preference should always be given to those processes which protect resources by permitting recovery of solvent. Substantial advances in the area of membrane technology during the past ten years mean that gas permeation now constitutes an interesting alternative to conventional processes. Combination of a membrane separation stage with direct or indirect condensation gives a hybrid process permitting gentle and contamination‐free recovery of organic components. This article briefly summarises the fundamentals of permeation of gas/vapour mixtures through polymer membranes.
Techniken und Anwendungen der Ultraschall‐Zerstäubung – Ein Rückblick auf 35 Jahre Forschung und Entwicklung
Authors: Lierke Ernst Günter
Published: December 2004

Techniques and Applications of Ultrasonic Atomisation – 35 Years of Research and Development in Retrospect. In the course of the last 50 years, ultrasonic atomisation has developed from a somewhat exotic laboratory technique with few, hardly used applications to a well established one with a broad spectrum of applications. Today's optimised atomisers for process engineering applications operate at volume flows between a few ml/min and several 100 l/h and droplet diameters between 1 and about 150 micrometers. The technique can handle both „normal”︁ liquids for therapeutic inhalation, for air humidifiers, carburettors, oil burners, etc. as well as solutions and suspensions for spray drying and melts of low to high melting temperatures and viscosities. The author reports on the development of ultrasonic atomisers and not only describes the physical principles and technical features of the various atomiser types but also considers borderline topics of droplet and particle generation with vibrating nozzles and cavitation chambers.
Biologischer Abbau chlorierter Kohlenwasserstoffe
Authors: Wiesmann Udo , Herbst Brendan
Published: December 2004

Biological Degradation of Chlorinated Hydrocarbons.

Chlorinated hydrocarbons (CHC) have been produced on an industrial scale since the 1920's and 1930's and are frequently used as solvents, extractants, and disinfectants. Because their low biodegradability they are often enriched in the food chains of animals, resulting in high mortality. It is therefore necessary to prevent the discharge of CHC's into water, air, and soil. They are often not biodegraded in municipal or industrial activated sludge plants or in trickling filters. Until harmless substitutes become widely available, CHC's will continue to pose a threat and must be eliminated from all effluents before entering wastewater treatment plants. Information about specific conditions for anaerobic and aerobic biodegradation of selected CHC's is given below. Two topics will be discussed in greater detail: the kinetics of dechlorination and mineralization and some examples of the reaction engineering process in lab and pilot scale.
Actin and alpha‐actinin dynamics in the adhesion and motility of EPEC and EHEC on host cells
Authors: Shaner Nathan C. , Sanger Joseph W. , Sanger Jean M.
Published: December 2004

Two pathogenic Escherichia coli, Enteropathogenic E. coli (EPEC) and Enterohemorrhagic E. coli (EHEC), adhere to the outside of host cells and induce cytoskeletal rearrangements leading to the formation of membrane‐encased pedestals comprised of actin filaments and other associated proteins beneath the bacteria. The structure of the pedestals induced by the two pathogens appears similar, although those induced by EHEC are shorter in length. Fluorescence Recovery After Photobleaching (FRAP) was used to determine potential differences of actin polymerization in EPEC and EHEC induced pedestals in cultured PtK2 cells expressing either Green or Yellow Fluorescent Protein (GFP or YFP) fused to actin or alpha‐actinin. When all the fluorescent actin in a pedestal on EPEC‐infected cells was photobleached, fluorescence recovery first occurred directly beneath the bacterium in a band that grew wider at a rate of one micron/minute. Consistently observed in all EPEC‐induced pedestals, whether they were stationary, lengthening, or translocating, the rate of actin polymerization that occurred at the pedestal tip was approximately 1 μm/min. Overall, a much slower rate of actin polymerization was measured in long EHEC‐induced pedestals. In contrast to the dynamics of GFP‐actin, recovery of GFP‐alpha‐actinin fluorescence was not polarized, with the actin cross‐linking protein exchanging all the length of the EPEC/EHEC induced pedestals. Surprisingly, the depolymerization and retrograde flow of pedestal actin, as well as pedestal translocations, were inhibited reversibly by either 2,3‐butanedione monoxime (BDM) or by a combination of sodium azide and 2‐deoxy D‐glucose, leading to an increase in the lengths of the pedestals. A simple physical model was developed to describe elongation and translocation of EPEC/EHEC pedestals in terms of actin polymerization and depolymerization dynamics. Cell Motil. Cytoskeleton 60:104–120, 2005. © 2004 Wiley‐Liss, Inc.
Universality of local eigenvalue statistics for some sample covariance matrices
Authors: Ben Arous Gérard , Péché Sandrine
Published: December 2004

We consider random, complex sample covariance matrices$${1 \over N}$$X*X, whereXis ap×Nrandom matrix with i.i.d. entries of distribution μ. It has been conjectured that both the distribution of the distance between nearest neighbor eigenvalues in thebulkand that of the smallest eigenvalues become, in the limitN→ ∞,$${p \over N}$$→ 1, the same as that identified for a complex Gaussian distribution μ. We prove these conjectures for a certain class of probability distributions μ. © 2004 Wiley Periodicals, Inc.
Structural phase transition in Tb5(Si0.6Ge0.4)4 at low temperature
Authors: Kupsch A. , Levin A. A. , Meyer D. C.
Published: December 2004

Herein we report on crystallographic details of a structural phase transition measured with powdered Tb5(Si0.6Ge0.4)4 at low temperatures (150 and 130 K). The pseudo‐binary compound is monoclinic at room temperature (P1121/a). Changes of reflection intensities and positions in the diffraction patterns indicate a structural phase transition between 100 K and 150 K, where the compound orders in an orthorhombic structure (Pnma). This is in accordance with a magnetic phase transition from paramagnetic to ferromagnetic state (TC = 150 K), where the compound exhibits the giant magnetocaloric effect. Split‐up crystallographic sites of the monoclinic unit cell degenerate to sites of higher symmetry in the orthorhombic structure. Changes in the corresponding bond lengths are listed in detail. It turned out that both phases coexist at the selected temperatures but the phase content changes significantly. The observed phase transition is very similar to that reported for Gd5Si2Ge2, that is a shear movement of pairs of nearly rigid slabs of atoms along a direction by 0.84 Å and the tremendous increase of selected (Si/Ge)‐(Si/Ge) distances from 2.64 to 3.59 Å in between those slabs. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
In situ high‐temperature X‐ray diffraction study of the Rb2O‐B2O3 glass forming system
Authors: Bubnova R. S. , Krzhizhanovskaya M. G. , Polyakova I. G. , Filatov S. K.
Published: December 2004

The results of X‐ray structural analysis, in situ powder high temperature X‐ray diffraction (HTXRD), DTA and annealing studies are summarized to refine the phase equilibria in the Rb2O‐B2O3 system in air. Samples were prepared by solid state reaction as well as by the crystallisation of glasses. Investigations show that, in the latter case, high‐temperature metastable phases crystallise first, and it takes some months to reach phase equilibria. The recent determination of crystal structures of Rb2B4O7, Rb3B7O12, Rb5B19O31, α,β‐RbB3O5 and β‐RbB5O8 along with the HTXRD and DTA study led to substantial revising of the Rb2O‐B2O3 phase diagram between the 5‐50 mol. % Rb2O compositions. New compounds Rb3B7O12 and Rb5B19O31 and new phase relations in this connection are presented. The low (α) and high temperature (β) modifications of RbB3O5 were discovered and α⟷β transition is studied in details by powder HTXRD. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The possibility of characterizing the severity of fires by a single parameter
Authors: Harmathy T. Z.
Published: December 2004

Because language conveys the idea of fire severity by a single expression, it has always seemed desirable to find a single variable for its quantification. The earlier suggestion by the author that the total heat absorption per unit surface area of the compartment boundaries during the period of full fire development, to be referred to as overall heat load, be used as a measure of destructive potential of fires, has been critically examined. It has been found that for many reinforced and prestressed concrete building elements, the overall heat load is indeed an approximate descriptor of the severity of compartment fires, irrespective of their temperature histories.
Smoke measurements: An assessment of correlations between laboratory and full‐scale experiments
Authors: Quintiere James G.
Published: December 2004

An extensive review is presented demonstrating the nature of comparison between full‐scale fire smoke data and test method results for materials. These correlations are presented in terms of consistent parameters established through a development of the governing equations for smoke concentration and light attenuation. Visibility data limited to light transmission through smoke are also presented. The complex dependence of smoke production on many parameters acting in fire growth limits the success of simple correlation methods. Recommendations are made for further research to establish a sound basis for correlations, and the prediction of smoke obscuration due to fire.
Theory of fire and fire processes
Authors: Rasbash D. J. , Drysdale D. D.
Published: December 2004

There are two major fire processes, an understanding of which is essential for effective fire safety design: (1) the conditions under which a combustible material may become involved in flaming combustion, and (2) the rate at which such a material, once involved, will provide an output of heat, smoke, toxic gases, etc., which can endanger people and property. The first process may be regarded as covering both ignition and spread of fire on materials; its complement is the way in which fire may become extinguished. It is necessary for such processes to bring in a characteristic of the basic combustion reaction which, directly or indirectly, expresses the reactivity of the combustion process. Thus pilot ignition is usually associated with an approximate surface fuel temperature. More basically, it is associated with a critical flow rate of volatiles and a critical heat loss from the flame, the latter being influenced by ambient oxygen and temperatures conditions as well as heat lost and gained by the fuel itself. The most important factor governing the production of dangerous product is the rate at which volatiles first (fuel controlled fires) and later air (air controlled fires) are fed into the flames. The reactivity is of less importance, although it may be one of the factors which control combustion efficiency. In general, the more efficient is the combustion the more heat is produced, but the less smoke and toxic gases are produced. Some of the main advances in the above areas are reviewed in this paper.
The behaviour of thermoset polymers under fire conditions
Authors: Nicholson John W. , Nolan Philip F.
Published: December 2004

This paper reviews the current literature on the behaviour of thermoset polymers under fire conditions. These polymers are important and widely used materials. They are generally infusible and insoluble, and consist, on the molecular scale, of extensive cross‐linked networks rather than discrete macromolecules. Materials in this class include phenol‐formaldehydes, epoxides, cross‐linked polyester, amino resins and polyurethanes. As the use of plastics generally has grown, so there have been changes in the conditions prevailing in modern fires, and such changes are described, together with the potential fire hazards arising from the varying uses of the individual thermosets. Subsequently, literature on the pyrolytic and combustion characteristics of these materials is reviewed in order to assess their probable behaviour in real fires. Finally, existing approaches towards improving their fire behaviour are described.
Correlation of smoke and fumes from overheated materials in an aircraft fuselage and in a laboratory test apparatus
Authors: Christopher A. J.
Published: December 2004

To assess the utility of a laboratory test for smoke and fume emission from overheated materials, six materials were heated to 500°C in larger amounts in three locations in an air‐conditioned aircraft fuselage on the ground. Smoke, acidic or alkaline gases and carbon monoxide were monitored. It was shown that the laboratory test results could be a basis for predicting the smoke‐ and fume‐emission behaviour of materials subjected to overheating, e. g. in aircraft in flight.
Effect of calcium carbonate filler on the fire and smoke properties of moulded polypropylene
Authors: Grayson S. J. , Smith D. A.
Published: December 2004

‘Oxygen Index’, ‘Rate of Burning and Extent of Burning of Self‐supporting Plastics in a Horizontal Position’ and ‘Vertical Flammability’ tests were used for examination of polypropylene copolymer HW 607M and the same copolymer filled with 40% w/w calcium carbonate. Room‐scale studies were also carried out using a range of standard ignition sources. In the latter tests, measurements of the levels of smoke generated in the test chamber were monitored continuously, and intermittent measurements were made of the carbon monoxide concentrations. Small‐scale testing showed that addition of the filler to the polypropylene raised the limiting oxygen index of the polymer from 17.8 to 20.3, which is only marginally lower than the oxygen concentration in ambient air (20.9); this introduces the possibility of a filled polypropylene which is not ignitable in air. However, the results of the UL94 and ASTM D635 tests did not show significant differences in flammability and rates of vertical and horizontal flame spread as between the two materials, through the unfilled polymer produced extensive burning droplets early in both tests whilst the filled polymer did not. Such droplets can spread fires to floor coverings, so that the filled plastic might be preferable in application. In our laboratory tests, the filled samples gave considerably lower smoke generation than the unfilled ones. At high heat fluxes they generated considerably less smoke than (smaller) unfilled samples containing the same mass of polymer. This suggests that the calcium carbonate has specific smoke‐suppressant activity and is not merely acting as a polymer diluent. In larger‐scale tests, unfilled samples were readily ignited by a domestic match, whilst the filled samples required an ignition source of 43 kJ (some six times greater than the match source) in order to light them and sustain ignition. The filled polymer did not melt on ignition and there was no lateral spread of flame from the sample. Smoke generation was considerably lower, the average optical density at maximum obscuration being 0.27, compared with 0.84 for the unfilled control. In particular, smoke suppression achieved by use of calcium carbonate at higher heat‐flux levels is considerably greater than that expected for an inert diluent.
Tomorrow's safety is today's research
Authors: Watters P.
Published: December 2004

The paper covers the effect fire has on the individual in Society and comments on the present day hazard arising from the use of chemicals in the industrial field, transportation and storage of chemicals, impact of technological changes and the ever increasing use in the home of furnishings. In order to identify future areas of research there is a need to consider what has happened in the past and in particular to look at social and economic factors of the development of fire. Comment is made on the difficulty of identifying unknown future hazards and covers areas of development which might create special problems. The domestic scene is examined in regard to construction and content and development of design standards in buildings. Human behaviour is discussed with comment on past tragedies and their aftermath with particular relevance to the reaction of people in fire situations. The future deals with use of flammables in the home. The paper concludes by observing how the author would envisage the development of the fire service to meet the unknown challenge that lies ahead and suggests one or two thoughts on how research, and researchers, can assist in making the world a safer place to live.