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  • 2015-2019
  • 2005-2009  (41)
  • 1985-1989
  • 1970-1974  (84)
  • 2008  (41)
  • 1971  (84)
  • Biochemistry and Biotechnology  (84)
  • ddc:510  (41)
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  • 2015-2019
  • 2005-2009  (41)
  • 1985-1989
  • 1970-1974  (84)
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  • 1
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    Diskrete Mathematik und ihre Anwendungen: Auf dem Weg zu authentischem Mathematikunterricht (2008)
    Details
    Publication Date: 2020-08-05
    Description: Das heutige Leben ist durchdrungen von komplexen Technologien. Ohne Kommunikationsnetze, Internet, Mobilfunk, Logistik, Verkehrstechnik, medizinische Apparate, etc. könnte die moderne Gesellschaft nicht funktionieren. Fast alle dieser Technologien haben einen hohen Mathematikanteil. Der "normale Bürger"' weiss davon nichts, der Schulunterricht könnte dem ein wenig abhelfen. Einige mathematische Aspekte dieser Technologien sind einfach und sogar spielerisch intuitiv zugänglich. Solche Anwendungen, die zusätzlich noch der Lebensumwelt der Schüler zugehören, können dazu genutzt werden, die mathematische Modellierung, also die mathematische Herangehensweise an die Lösung praktischer Fragen, anschaulich zu erläutern. Gerade in der diskreten Mathematik können hier, quasi "nebenbei" mathematische Theorien erarbeitet und Teilaspekte (Definitionen, Fragestellungen, einfache Sachverhalte) durch eigenständiges Entdecken der Schüler entwickelt werden. Wir beginnen mit einigen Beispielen.
    Keywords: ddc:510
    Language: German
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  • 2
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    Wegeprobleme der Graphentheorie (2008)
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    Publication Date: 2020-08-05
    Description: Den kürzesten Weg in einem Graphen zu finden ist ein klassisches Problem der Graphentheorie. Über einen Vortrag zu diesem Thema beim Tag der Mathematik 2007 von R. Borndörfer kam ich in Kontakt mit dem Konrad-Zuse-Zentrum (ZIB), das sich u.a. mit Wegeoptimierung beschäftigt. Ein Forschungsschwerpunkt dort ist im Rahmen eines Projekts zur Chipverifikation das Zählen von Lösungen, das, wie wir sehen werden, eng mit dem Zählen von Wegen zusammenhängt. Anhand von zwei Fragen aus der Graphentheorie soll diese Facharbeit unterschiedliche Lösungsmethoden untersuchen. Wie bestimmt man den kürzesten Weg zwischen zwei Knoten in einem Graphen und wie findet man alle möglichen Wege? Nach einer Einführung in die Graphentheorie und einer Konkretisierung der Probleme wird zunächst für beide eine Lösung mit auf Graphen basierenden Algorithmen vorgestellt. Während der Algorithmus von Dijkstra sehr bekannt ist, habe ich für das Zählen von Wegen einen eigenen Algorithmus auf der Basis der Tiefensuche entwickelt. Im zweiten Teil der Arbeit wird das Konzept der ganzzahligen Programmierung vorgestellt und die Lösungsmöglichkeiten für Wegeprobleme, die sich darüber ergeben. Schließlich wurden die vorgestellten Algorithmen am Beispiel des S- und U-Bahnnetzes von Berlin implementiert und mit Programmen, die die gleichen Fragen über ganzzahlige Programmierung lösen, verglichen.
    Keywords: ddc:510
    Language: German
    Type: reportzib , doc-type:preprint
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  • 3
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    A Perturbation Result for Dynamical Contact Problems (2008)
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    Publication Date: 2016-06-09
    Description: This paper is intended to be a first step towards the continuous dependence of dynamical contact problems on the initial data as well as the uniqueness of a solution. Moreover, it provides the basis for a proof of the convergence of popular time integration schemes as the Newmark method. We study a frictionless dynamical contact problem between both linearly elastic and viscoelastic bodies which is formulated via the Signorini contact conditions. For viscoelastic materials fulfilling the Kelvin-Voigt constitutive law, we find a characterization of the class of problems which satisfy a perturbation result in a non-trivial mix of norms in function space. This characterization is given in the form of a stability condition on the contact stresses at the contact boundaries. Furthermore, we present perturbation results for two well-established approximations of the classical Signorini condition: The Signorini condition formulated in velocities and the model of normal compliance, both satisfying even a sharper version of our stability condition.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 4
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    An Integer Programming Algorithm for Routing Optimization in IP Networks (2008)
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    Publication Date: 2020-08-05
    Description: Most data networks nowadays use shortest path protocols to route the traffic. Given administrative routing lengths for the links of the network, all data packets are sent along shortest paths with respect to these lengths from their source to their destination. In this paper, we present an integer programming algorithm for the minimum congestion unsplittable shortest path routing problem, which arises in the operational planning of such networks. Given a capacitated directed graph and a set of communication demands, the goal is to find routing lengths that define a unique shortest path for each demand and minimize the maximum congestion over all links in the resulting routing. We illustrate the general decomposition approach our algorithm is based on, present the integer and linear programming models used to solve the master and the client problem, and discuss the most important implementational aspects. Finally, we report computational results for various benchmark problems, which demonstrate the efficiency of our algorithm.
    Keywords: ddc:510
    Language: English
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  • 5
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    The Line Connectivity Problem (2008)
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    Publication Date: 2020-12-15
    Description: This paper introduces the "line connectivity problem", a generalization of the Steiner tree problem and a special case of the line planning problem. We study its complexity and give an IP formulation in terms of an exponential number of constraints associated with "line cut constraints". These inequalities can be separated in polynomial time. We also generalize the Steiner partition inequalities.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 6
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    Using Model Counting to Find Optimal Distinguishing Tests (2008)
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    Publication Date: 2020-08-05
    Description: Testing is the process of stimulating a system with inputs in order to reveal hidden parts of the system state. In the case of non-deterministic systems, the difficulty arises that an input pattern can generate several possible outcomes. Some of these outcomes allow to distinguish between different hypotheses about the system state, while others do~not. In this paper, we present a novel approach to find, for non-deterministic systems modeled as constraints over variables, tests that allow to distinguish among the hypotheses as good as possible. The idea is to assess the quality of a test by determining the ratio of distinguishing (good) and not distinguishing (bad) outcomes. This measure refines previous notions proposed in the literature on model-based testing and can be computed using model counting techniques. We propose and analyze a greedy-type algorithm to solve this test optimization problem, using existing model counters as a building block. We give preliminary experimental results of our method, and discuss possible improvements.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 7
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    On the Effects of Minor Changes in Model Formulations (2008)
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    Publication Date: 2021-08-05
    Description: Starting with the description of the Traveling Salesmen Problem formulation as given by van Vyve and Wolsey in the article Approximate extended formulations'', we investigate the effects of small variations onto the performance of contemporary mixed integer programming solvers. We will show that even minor changes in the formulation of the model can result in performance difference of more than a factor of 1000. As the results show it is not obvious which changes will result in performance improvements and which not.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 8
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    Detecting Orbitopal Symmetries (2008)
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    Publication Date: 2022-03-14
    Description: Orbitopes can be used to handle symmetries which arise in integer programming formulations with an inherent assignment structure. We investigate the detection of symmetries appearing in this approach. We show that detecting so-called orbitopal symmetries is graph-isomorphism hard in general, but can be performed in linear time if the assignment structure is known.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 9
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    Optimization and Identification in Regional Hyperthermia (2008)
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    Publication Date: 2019-01-29
    Description: Regional hyperthermia is a cancer therapy aiming at heating tumors using phased array applicators. This article provides an overview over current mathematical challenges of delivering individually optimal treatments. The focus is on therapy planning and identification of technical as well as physiological quantities from MR thermometry measurements.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 10
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    On Efficiency and Accuracy in Cardioelectric Simulation (2008)
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    Publication Date: 2019-05-10
    Description: Reasons for the failure of adaptive methods to deliver improved efficiency when integrating monodomain models for myocardiac excitation are discussed. Two closely related techniques for reducing the computational complexity of linearly implicit integrators, deliberate sparsing and splitting, are investigated with respect to their impact on computing time and accuracy.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 11
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    Models for Periodic Timetabling (2008)
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    Publication Date: 2020-08-05
    Description: We investigate the computation of periodic timetables for public transport by mixed integer programming. After introducing the problem, we describe two mathematical models for periodic timetabling, the PERIODIC EVENT SCHEDULING PROBLEM (PESP) and the QUADRATIC SEMI-ASSIGNMENT PROBLEM. Specifically, we give an overview of existing integer programming (IP) formulations for both models. An important contribution of our work are new IP formulations for the PESP based on time discretization. We provide an analytical comparison of these formulations and describe different techniques that allow a more efficient solution by mixed integer programming. In a preliminary computational study, on the basis of standard IP solvers, we compare different formulations for computing periodic timetables. Our results justify a further investigation of the time discretization approach. Typically the timetable is optimized for the current traffic situation. The main difficulty with this approach is that after introducing the new timetable the passengers’ travel behavior may differ from that assumed for the computation. Motivated by this problem, we examine an iterative timetabling procedure that is a combination of timetable computation and passenger routing. We discuss the algorithmic issues of the passenger routing and study properties of the computed timetables. Finally, we confirm our theoretical results on the basis of an own implementation.
    Description: Wir untersuchen die Berechnung von Taktfahrplänen für den öffentlichen Verkehr mit gemischt-ganzzahliger Programmierung (MIP). Im Anschluss an die Problembeschreibung, stellen wir zwei mathematische Modellierungen vor, das PERIODIC EVENT SCHEDULING PROBLEM (PESP) und das QUADRATIC SEMI-ASSIGNMENT PROBLEM. Wichtiger Bestandteil ist ein Überblick über existierende ganzzahlige Formulierungen beider Modelle. Wir entwickeln neue ganzzahlige Formulierungen für das PESP auf der Basis von Zeitdiskretisierung. Diese werden analytisch miteinander verglichen und wir beschreiben verschiedene Techniken, die eine effizientere Lösung der Formulierungen mit gemischt-ganzzahliger Programmierung ermöglichen. In einer ersten Rechenstudie, unter Verwendung gängiger MIP-Löser, vergleichen wir verschiedene ganzzahlige Formulierungen zur Berechnung von Taktfahrplänen. Unsere Ergebnisse rechtfertigen eine weitere Untersuchung des Zeitdiskretisierungsansatzes. In der Regel werden Fahrpläne mit Bezug auf die gegenwärtige Verkehrssituation optimiert. Dies birgt jedoch folgendes Problem. Wenn der neue Fahrplan eingeführt wird, ist es möglich, dass die Passagiere ein anderes Fahrverhalten zu Tage legen, als für die Berechnung des Fahrplans angenommen wurde. Vor diesem Hintergrund behandeln wir ein iteratives Verfahren zur Berechnung von Taktfahrplänen. Dieses ist eine Kombination aus Fahrplanberechnung und Passagierrouting. Neben den algorithmischen Details des Passagierroutings untersuchen wir Eigenschaften der berechneten Fahrpläne. Abschließend bestätigen wir unsere theoretischen Ergebnisse auf Grundlage einer eigenen Implementierung des Verfahrens.
    Keywords: ddc:510
    Language: English
    Type: masterthesis , doc-type:masterThesis
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  • 12
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    Experiments with nonlinear extensions to SCIP (2008)
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    Publication Date: 2020-08-05
    Description: This paper describes several experiments to explore the options for solving a class of mixed integer nonlinear programming problems that stem from a real-world mine production planning project. The only type of nonlinear constraints in these problems are bilinear equalities involving continuous variables, which enforce the ratios between elements in mixed material streams. A branch-and-bound algorithm to handle the integer variables has been tried in another project. However, this branch-and-bound algorithm is not effective for handling the nonlinear constraints. Therefore state-of-the-art nonlinear solvers are utilized to solve the resulting nonlinear subproblems in this work. The experiments were carried out using the NEOS server for optimization. After finding that current nonlinear programming solvers seem to lack suitable preprocessing capabilities, we preprocess the instances beforehand and use an heuristic approach to solve the nonlinear subproblems. In the appendix, we explain how to add a polynomial constraint handler that uses IPOPT as embedded nonlinear programming solver for the constraint programming framework SCIP. This is one of the crucial steps for implementing our algorithm in SCIP. We briefly described our approach and give an idea of the work involved.
    Keywords: ddc:510
    Language: English
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  • 13
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    Tiefensuche: Bemerkungen zur Algorithmengeschichte (2008)
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    Publication Date: 2020-08-05
    Description: Dieser kurze Aufsatz zur Algorithmengeschichte ist Eberhard Knobloch, meinem Lieblings-Mathematikhistoriker, zum 65. Geburtstag gewidmet. Eberhard Knobloch hat immer, wenn ich ihm eine historische Frage zur Mathematik stellte, eine Antwort gewusst – fast immer auch sofort. Erst als ich mich selbst ein wenig und dazu amateurhaft mit Mathematikgeschichte beschäftigte, wurde mir bewusst, wie schwierig dieses „Geschäft“ ist. Man muss nicht nur mehrere (alte) Sprachen beherrschen, sondern auch die wissenschaftliche Bedeutung von Begriffen und Symbolen in früheren Zeiten kennen. Man muss zusätzlich herausfinden, was zur Zeit der Entstehung der Texte „allgemeines Wissen“ war, insbesondere, was seinerzeit gültige Beweisideen und -schritte waren, und daher damals keiner präzisen Definition oder Einführung bedurfte. Es gibt aber noch eine Steigerung des historischen Schwierigkeitsgrades: Algorithmengeschichte. Dies möchte ich in diesem Artikel kurz darlegen in der Hoffnung, dass sich Wissenschaftshistoriker dieses Themas noch intensiver annehmen, als sie das bisher tun. Der Grund ist, dass heute Algorithmen viele Bereiche unserer Alltagswelt steuern und unser tägliches Leben oft von funktionierenden Algorithmen abhängt. Daher wäre eine bessere Kenntnis der Algorithmengeschichte von großem Interesse.
    Keywords: ddc:510
    Language: German
    Type: reportzib , doc-type:preprint
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  • 14
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    State constrained optimal control problems with states of low regularity (2008)
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    Publication Date: 2016-06-09
    Description: We consider first order optimality conditions for state constrained optimal control problems. In particular we study the case where the state equation has not enough regularity to admit existence of a Slater point in function space. We overcome this difficulty by a special transformation. Under a density condition we show existence of Lagrange multipliers, which have a representation via measures and additional regularity properties.
    Keywords: ddc:510
    Language: English
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  • 15
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    Properties of Reduced Reversible Markov Chains (2008)
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    Publication Date: 2016-06-09
    Description: The enormous time lag between fast atomic motion and complex pro- tein folding events makes it almost impossible to compute molecular dy- namics on a high resolution. A common way to tackle this problem is to model the system dynamics as a Markov process. Yet for large molec- ular systems the resulting Markov chains can hardly be handled due to the curse of dimensionality. Coarse graining methods can be used to re- duce the dimension of a Markov chain, but it is still unclear how far the coarse grained Markov chain resembles the original system. In order to answer this question, two different coarse-graining methods were analysed and compared: a classical set-based reduction method and an alternative subspace-based approach, which is based on membership vectors instead of sets. On the basis of a small toy system, it could be shown, that in con- trast to the subset-based approach, the subspace-based reduction method preserves the Markov property as well as the essential dynamics of the original system.
    Keywords: ddc:510
    Language: English
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  • 16
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    Line Planning on Paths and Tree Networks with Applications to the Quito Trolebus System (2008)
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    Publication Date: 2021-02-19
    Description: Line planning is an important step in the strategic planning process of a public transportation system. In this paper, we discuss an optimization model for this problem in order to minimize operation costs while guaranteeing a certain level of quality of service, in terms of available transport capacity. We analyze the problem for path and tree network topologies as well as several categories of line operation that are important for the Quito Trolebus system. It turns out that, from a computational complexity worst case point of view, the problem is hard in all but the most simple variants. In practice, however, instances based on real data from the Trolebus System in Quito can be solved quite well, and significant optimization potentials can be demonstrated.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 17
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    On the optimality of Least Recently Used (2008)
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    Publication Date: 2020-08-05
    Description: It is well known that competitive analysis yields too pessimistic results when applied to the paging problem and it also cannot make a distinction between many paging strategies. Many deterministic paging algorithms achieve the same competitive ratio, ranging from inefficient strategies as flush-when-full to the good performing least-recently-used (LRU). In this paper, we study this fundamental online problem from the viewpoint of stochastic dominance. We show that when sequences are drawn from distributions modelling locality of reference, LRU is stochastically better than any other online paging algorithm.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 18
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    Angebotsplanung im öffentlichen Nahverkehr (2008)
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    Publication Date: 2020-12-15
    Description: Die Angebotsplanung im öffentlichen Nahverkehr umfasst die Aufgaben der Netz-, Linien-,Fahr- und Preisplanung. Wir stellen zwei mathematische Optimierungsmodelle zur Linien- und Preisplanung vor. Wir zeigen anhand von Berechnungen für die Verkehrsbetriebe in Potsdam(ViP), dass sich damit komplexe Zusammenhänge quantitativ analysieren lassen. Auf diese Weise untersuchen wir die Auswirkungen von Freiheitsgraden auf die Konstruktion von Linien und die Wahl von Reisewegen der Passagiere, Abhängigkeiten zwischen Kosten und Reisezeiten sowie den Einfluss verschiedener Preissysteme auf Nachfrage und Kostendeckung.
    Keywords: ddc:510
    Language: German
    Type: reportzib , doc-type:preprint
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  • 19
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    Constraint Integer Programming: a New Approach to Integrate CP and MIP (2008)
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    Publication Date: 2022-03-14
    Description: This article introduces constraint integer programming (CIP), which is a novel way to combine constraint programming (CP) and mixed integer programming (MIP) methodologies. CIP is a generalization of MIP that supports the notion of general constraints as in CP. This approach is supported by the CIP framework SCIP, which also integrates techniques from SAT solving. SCIP is available in source code and free for non-commercial use. We demonstrate the usefulness of CIP on two tasks. First, we apply the constraint integer programming approach to pure mixed integer programs. Computational experiments show that SCIP is almost competitive to current state-of-the-art commercial MIP solvers. Second, we employ the CIP framework to solve chip design verification problems, which involve some highly non-linear constraint types that are very hard to handle by pure MIP solvers. The CIP approach is very effective here: it can apply the full sophisticated MIP machinery to the linear part of the problem, while dealing with the non-linear constraints by employing constraint programming techniques.
    Keywords: ddc:510
    Language: English
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  • 20
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    An Extended Mathematical Framework for Barrier Methods in Function Space (2008)
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    Publication Date: 2016-06-09
    Description: An extended mathematical framework for barrier methods for state constrained optimal control compared to [Schiela, ZIB-Report 07-07] is considered. This allows to apply the results derived there to more general classes of optimal control problems, in particular to boundary control and finite dimensional control.
    Keywords: ddc:510
    Language: English
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  • 21
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    Counting solutions of integer programs using unrestricted subtree detection (2008)
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    Publication Date: 2021-08-05
    Description: In the recent years there has been tremendous progress in the development of algorithms to find optimal solutions for integer programs. In many applications it is, however, desirable (or even necessary) to generate all feasible solutions. Examples arise in the areas of hardware and software verification and discrete geometry. In this paper, we investigate how to extend branch-and-cut integer programming frameworks to support the generation of all solutions. We propose a method to detect so-called unrestricted subtrees, which allows us to prune the integer program search tree and to collect several solutions simultaneously. We present computational results of this branch-and-count paradigm which show the potential of the unrestricted subtree detection.
    Keywords: ddc:510
    Language: English
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  • 22
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    On the cardinality constrained matroid polytope (2008)
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    Publication Date: 2020-08-05
    Description: Edmonds showed that the so-called rank inequalities and the nonnegativity constraints provide a complete linear description of the matroid polytope. By essentially adding Grötschel's cardinality forcing inequalities, we obtain a complete linear description of the cardinality constrained matroid polytope which is the convex hull of the incidence vectors of those independent sets that have a feasible cardinality. Moreover, we show how the separation problem for the cardinality forcing inequalities can be reduced to that for the rank inequalities. We also give necessary and sufficient conditions for a cardinality forcing inequality to be facet defining.
    Keywords: ddc:510
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  • 23
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    On solving large systems of polynomial equations appearing in Discrete Differential Geometry (2008)
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    Publication Date: 2020-08-05
    Description: The paper describes a method for solution of very large overdetermined algebraic polynomial systems on an example that appears from a classification of all integrable 3-dimensional scalar discrete quasilinear equations $Q_3=0$ on an elementary cubic cell of the lattice ${\mathbb Z}^3$. The overdetermined polynomial algebraic system that has to be solved is far too large to be formulated. A probing' technique which replaces independent variables by random integers or zero allows to formulate subsets of this system. An automatic alteration of equation formulating steps and equation solving steps leads to an iteration process that solves the computational problem.
    Keywords: ddc:510
    Language: English
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  • 24
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    Invertible Mappings of Nonlinear PDEs to Linear PDEs Through Admitted Conservation Laws (2008)
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    Publication Date: 2020-08-05
    Description: An algorithmic method using conservation law multipliers is introduced that yields necessary and sufficient conditions to find invertible mappings of a given nonlinear PDE to some linear PDE and to construct such a mapping when it exists. Previous methods yielded such conditions from admitted point or contact symmetries of the nonlinear PDE. Through examples, these two linearization approaches are contrasted.
    Keywords: ddc:510
    Language: English
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  • 25
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    Classification of 3-dimensional integrable scalar discrete equations (2008)
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    Publication Date: 2021-02-26
    Description: We classify all integrable 3-dimensional scalar discrete affine linear equations $Q_3=0$ on an elementary cubic cell of the lattice ${\mathbb Z}^3$. An equation $Q_3=0$ %of such form is called integrable if it may be consistently imposed on all $3$-dimensional elementary faces of the lattice ${\mathbb Z}^4$. Under the natural requirement of invariance of the equation under the action of the complete group of symmetries of the cube we prove that the only ontrivial(non-linearizable) integrable equation from this class is the well-known dBKP-system.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 26
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    About a Computer Algebra based online Mathtest (2008)
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    Publication Date: 2020-12-11
    Description: The article describes the online mathematics test {\tt http://lie.math.brocku.ca/mathtest}, its typical applications and experiences gathered.
    Keywords: ddc:510
    Language: English
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    TTPLIB 2008 - A Library for Train Timetabling Problems (2008)
    Details
    Publication Date: 2020-08-05
    Description: We introduce (TTPlib), a data library for train timetabling problems that can be accessed at http://ttplib.zib.de. In version 1.0, the library contains data related to 50 scenarios. Most instances result from the combination of macroscopic railway networks and several train request sets for the German long distance area containing Hannover, Kassel and Fulda, short denoted by Ha-Ka-Fu. In this paper, we introduce the data concepts of TTPlib, describe the scenarios included in the library and provide a free visualization tool TraVis.
    Keywords: ddc:510
    Language: English
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    The Parametric Solution of Underdetermined linear ODEs (2008)
    Details
    Publication Date: 2020-08-05
    Description: The purpose of this paper is twofold. An immediate practical use of the presented algorithm is its applicability to the parametric solution of underdetermined linear ordinary differential equations (ODEs) with coefficients that are arbitrary analytic functions in the independent variable. A second conceptual aim is to present an algorithm that is in some sense dual to the fundamental Euclids algorithm, and thus an alternative to the special case of a Gr\"{o}bner basis algorithm as it is used for solving linear ODE-systems. In the paper Euclids algorithm and the new dual version' are compared and their complementary strengths are analysed on the task of solving underdetermined ODEs. An implementation of the described algorithm is interactively accessible at http://lie.math.brocku.ca/crack/uode.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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    Probabilistic analysis of Online Bin Coloring algorithms via Stochastic Comparison (2008)
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    Publication Date: 2020-08-05
    Description: This paper proposes a new method for probabilistic analysis of online algorithms that is based on the notion of stochastic dominance. We develop the method for the Online Bin Coloring problem introduced by Krumke et al. Using methods for the stochastic comparison of Markov chains we establish the strong result that the performance of the online algorithm GreedyFit is stochastically dominated by the performance of the algorithm OneBin for any number of items processed. This result gives a more realistic picture than competitive analysis and explains the behavior observed in simulations.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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    Models for Fare Planning in Public Transport (2008)
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    Publication Date: 2020-12-15
    Description: The optimization of fare systems in public transit allows to pursue objectives such as the maximization of demand, revenue, profit, or social welfare. We propose a non-linear optimization approach to fare planning that is based on a detailed discrete choice model of user behavior. The approach allows to analyze different fare structures, optimization objectives, and operational scenarios involving, e.g., subsidies. We use the resulting models to compute optimized fare systems for the city of Potsdam, Germany.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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    Solving Pseudo-Boolean Problems with SCIP (2008)
    Details
    Publication Date: 2022-03-14
    Description: Pseudo-Boolean problems generalize SAT problems by allowing linear constraints and a linear objective function. Different solvers, mainly having their roots in the SAT domain, have been proposed and compared,for instance, in Pseudo-Boolean evaluations. One can also formulate Pseudo-Boolean models as integer programming models. That is,Pseudo-Boolean problems lie on the border between the SAT domain and the integer programming field. In this paper, we approach Pseudo-Boolean problems from the integer programming side. We introduce the framework SCIP that implements constraint integer programming techniques. It integrates methods from constraint programming, integer programming, and SAT-solving: the solution of linear programming relaxations, propagation of linear as well as nonlinear constraints, and conflict analysis. We argue that this approach is suitable for Pseudo-Boolean instances containing general linear constraints, while it is less efficient for pure SAT problems. We present extensive computational experiments on the test set used for the Pseudo-Boolean evaluation 2007. We show that our approach is very efficient for optimization instances and competitive for feasibility problems. For the nonlinear parts, we also investigate the influence of linear programming relaxations and propagation methods on the performance. It turns out that both techniques are helpful for obtaining an efficient solution method.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
    Format: application/pdf
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    Planung von öffentlichem Personenverkehr (2008)
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    Publication Date: 2020-08-05
    Description: Millionen von Menschen werden allein in Deutschland täglich von Bussen, Bahnen und Flugzeugen transportiert. Der öffentliche Personenverkehr (ÖV) ist von großer Bedeutung für die Lebensqualität einzelner aber auch für die Leistungsfähigkeit ganzer Regionen. Qualität und Effizienz von ÖV-Systemen hängen ab von politischen Rahmenbedingungen (staatlich geplant, wettbewerblich organisiert) und der Eignung der Infrastruktur (Schienensysteme, Flughafenstandorte), vom vorhandenen Verkehrsangebot (Fahr- und Flugplan), von der Verwendung angemessener Technologien (Informations-, Kontroll- und Buchungssysteme) und dem bestmöglichen Einsatz der Betriebsmittel (Energie, Fahrzeuge und Personal). Die hierbei auftretenden Entscheidungs-, Planungs- und Optimierungsprobleme sind z.T. gigantisch und "schreien" aufgrund ihrer hohen Komplexität nach Unterstützung durch Mathematik. Dieser Artikel skizziert den Stand und die Bedeutung des Einsatzes von Mathematik bei der Planung und Durchführung von öffentlichem Personenverkehr, beschreibt die bestehenden Herausforderungen und regt zukunftsweisende Maßnahmen an.
    Keywords: ddc:510
    Language: German
    Type: reportzib , doc-type:preprint
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  • 33
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    Development and test of a numerical model for pulse thermography in civil engineering (2008)
    Details
    Publication Date: 2019-05-10
    Description: Pulse thermography of concrete structures is used in civil engineering for detecting voids, honeycombing and delamination. The physical situation is readily modeled by Fourier's law. Despite the simplicity of the PDE structure, quantitatively realistic numerical 3D simulation faces two major obstacles. First, the short heating pulse induces a thin boundary layer at the heated surface which encapsulates all information and therefore has to be resolved faithfully. Even with adaptive mesh refinement techniques, obtaining useful accuracies requires an unsatisfactorily fine discretization. Second, bulk material parameters and boundary conditions are barely known exactly. We address both issues by a semi-analytic reformulation of the heat transport problem and by parameter identification. Numerical results are compared with measurements of test specimens.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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    Barrier Methods for Optimal Control Problems with Convex Nonlinear Gradient Constraints (2008)
    Details
    Publication Date: 2016-06-09
    Description: In this paper we are concerned with the application of interior point methods in function space to gradient constrained optimal control problems, governed by partial differential equations. We will derive existence of solutions together with first order optimality conditions. Afterwards we show continuity of the central path, together with convergence rates depending on the interior point parameter.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 35
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    Interior Point Methods in Function Space for State Constraints - Inexact Newton and Adaptivity (2008)
    Details
    Publication Date: 2016-06-09
    Description: We consider an interior point method in function space for PDE constrained optimal control problems with state constraints. Our emphasis is on the construction and analysis of an algorithm that integrates a Newton path-following method with adaptive grid refinement. This is done in the framework of inexact Newton methods in function space, where the discretization error of each Newton step is controlled by adaptive grid refinement in the innermost loop. This allows to perform most of the required Newton steps on coarse grids, such that the overall computational time is dominated by the last few steps. For this purpose we propose an a-posteriori error estimator for a problem suited norm.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 36
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    Fair Ticket Prices in Public Transport (2008)
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    Publication Date: 2020-08-05
    Description: Ticket pricing in public transport usually takes a welfare or mnemonics maximization point of view. These approaches do not consider fairness in the sense that users of a shared infrastructure should pay for the costs that they generate. We propose an ansatz to determine fair ticket prices that combines concepts from cooperative game theory and integer programming. An application to pricing railway tickets for the intercity network of the Netherlands demonstrates that, in this sense, prices that are much fairer than standard ones can be computed in this way.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 37
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    A sharp interface finite volume method for elliptic equations on Cartesian grids (2008)
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    Publication Date: 2014-02-26
    Description: We present a second order sharp interface finite volume method for the solution of the three-dimensional poisson equation with variable coefficients on Cartesian grids. In particular, we focus on interface problems with discontinuities in the coefficient, the source term, the solution, and the fluxes across the interface. The method uses standard piecewiese trilinear finite elements for normal cells and a double piecewise trilinear ansatz for the solution on cells intersected by the interface resulting always in a compact 27-point stencil. Singularities associated with vanishing partial volumes of intersected grid cells are removed by a two-term asymptotic approach. In contrast to the 2D method presented by two of the authors in [M.~Oevermann, R.~Klein: A Cartesian grid finite volume method for elliptic equations with variable coefficients and embedded interfaces, J.~Comp.~Phys.~219 (2006)] we use a minimization technique to determine the unknown coefficients of the double trilinear ansatz. This simplifies the treatment of the different cut-cell types and avoids additional special operations for degenerated interface topologies. The resulting set of linear equations has been solved with a BiCGSTAB solver preconditioned with an algebraic multigrid. In various testcases -- including large coefficient ratios and non-smooth interfaces -- the method achieves second order of accuracy in the L_inf and L_2 norm.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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    Cardinality Constrained Combinatorial Optimization: Complexity and Polyhedra (2008)
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    Publication Date: 2020-08-05
    Description: Given a combinatorial optimization problem and a subset $N$ of natural numbers, we obtain a cardinality constrained version of this problem by permitting only those feasible solutions whose cardinalities are elements of $N$. In this paper we briefly touch on questions that addresses common grounds and differences of the complexity of a combinatorial optimization problem and its cardinality constrained version. Afterwards we focus on polytopes associated with cardinality constrained combinatorial optimization problems. Given an integer programming formulation for a combinatorial optimization problem, by essentially adding Grötschel's cardinality forcing inequalities, we obtain an integer programming formulation for its cardinality restricted version. Since the cardinality forcing inequalities in their original form are mostly not facet defining for the associated polyhedra, we discuss possibilities to strengthen them.
    Keywords: ddc:510
    Language: English
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    On the complexity of column generation in survivable network design with path-based survivability mechanisms (2008)
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    Publication Date: 2020-08-05
    Description: This survey concerns optimization problems arising in the design of survivable communication networks. It turns out that such problems can be modeled in a natural way as non-compact linear programming formulations based on multicommodity flow network models. These non-compact formulations involve an exponential number of path flow variables, and therefore require column generation to be solved to optimality. We consider several path-based survivability mechanisms and present results, both known and new, on the complexity of the corresponding column generation problems (called the pricing problems). We discuss results for the case of the single link (or node) failures scenarios, and extend the considerations to multiple link failures. Further, we classify the design problems corresponding to different survivability mechanisms according to the structure of their pricing problem. Finally, we show that almost all encountered pricing problems are hard to solve for scenarios admitting multiple failures.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 40
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    On the Line Planning Problem in Tree Networks (2008)
    Details
    Publication Date: 2021-02-19
    Description: We introduce an optimization model for the line planning problem in a public transportation system that aims at minimizing operational costs while ensuring a given level of quality of service in terms of available transport capacity. We discuss the computational complexity of the model for tree network topologies and line structures that arise in a real-world application at the Trolebus Integrated System in Quito. Computational results for this system are reported.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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    Line Planning on Paths and Tree Networks with Applications to the Quito Trolebus System (Extended Abstract) (2008)
    Details
    Publication Date: 2021-02-19
    Description: Line planning is an important step in the strategic planning process of a public transportation system. In this paper, we discuss an optimization model for this problem in order to minimize operation costs while guaranteeing a certain level of quality of service, in terms of available transport capacity. We analyze the problem for path and tree network topologies as well as several categories of line operation that are important for the Quito Trolebus system. It turns out that, from a computational complexity worst case point of view, the problem is hard in all but the most simple variants. In practice, however, instances based on real data from the Trolebus System in Quito can be solved quite well, and significant optimization potentials can be demonstrated.
    Keywords: ddc:510
    Language: English
    Type: reportzib , doc-type:preprint
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  • 42
    Electronic Resource
    Electronic Resource
    A generalization of kinetic data on sulphite oxidation systems (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 353-369 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Kinetic data of the reaction between sulphite ions and dissolved oxygen depend on the purity of sulphite used. Thus it is adequate to determine them for each batch and concentration of sulphite used. Besides the dependence of reaction rate constants on catalyst concentration, it is usually also required to know their dependence on pH and on temperature. Both quantities can change to a great extent especially in absorption apparatus in which high sulphite conversion occurs. They profoundly influence the value of the reaction rate constant. To get a complete picture of the influence of these three quantities without repeating extensive kinetic measurements for every kind and concentration of sulphite used, a method for obtaining information on the influence of all three quoted quantities in the range of values of interest for application is presented.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130303
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  • 43
    Electronic Resource
    Electronic Resource
    A comparative study of immobilized amyloglucosidase in a packed bed reactor and a continuous feed stirred tank reactor (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 337-352 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The catalytic activity of amyloglucosidase covalently attached to DEAE-cellulose was studied in a packed bed reactor and a continuous feed stirred tank reactor (CSTR) for the reaction maltose → glucose. At low flow rates mass-transfer limitations in the bed reactor lead to lower conversions for this reactor compared to the CSTR. Simple theoretical expressions for these reactors were compared with the experimental results. There are significant differences between the kinetic parameters and pH profile of the immobilized and free enzyme. The immobilized enzyme also showed greater stability at 50°C than did free amyloglucosidase. The temperature dependence of the reaction rate was the same for immobilized and free enzyme.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130302
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  • 44
    Electronic Resource
    Electronic Resource
    Some difficulties in fitting dynamic models to experimental transient data in continuous culture (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 451-452 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130312
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  • 45
    Electronic Resource
    Electronic Resource
    “Loading velocity” in aerobic biological waste treatment systems (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 449-450 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130311
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  • 46
    Electronic Resource
    Electronic Resource
    Masthead (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130401
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  • 47
    Electronic Resource
    Electronic Resource
    Apparatus for continuous, large-volume suspended cell cultivation (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 457-470 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A 30-liter apparatus for growing cells continuously is described. Samples are taken automatically, thus obviating one of the main causes of contamination. In order to eliminate the continuous introduction of a gas stream, the pH was kept constant by means of the injection of NH4OH or NaOH. Under these circumstances, and by means of the two methods of agitation described - rotary and “by Vibromixer” - a quantity of cells of approximately 4 × 1010 is harvested every 48 to 72 hr.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130402
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  • 48
    Electronic Resource
    Electronic Resource
    Sequential 11α-hydroxylation and 1-dehydrogenation of 16α-hydroxycortexolone (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 503-515 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two-step microbial transformation of 16α-hydroxycortexolone to its 1-dehydro-11α-hydroxy derivative, without isolating an intermediate, was achieved with an overall yield of 72% of product at a steroid substrate concentration of 3 mg/ml. The process included formation of the cycloborate complex of the substrate, hydroxylation of the borate complex with a suspension of Aspergillus ochraceus mycelium in phosphate buffer, and dehydrogenation of the 11α-hydroxylated intermediate with acetone-dried Arthrobacter simplex cells. The desired product was then obtained by breaking the resultant borate complex through acidification.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130405
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  • 49
    Electronic Resource
    Electronic Resource
    A radiometric method for determination of the oil drop size distribution in hydrocarbon-water systems (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 685-689 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130508
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  • 50
    Electronic Resource
    Electronic Resource
    Masthead (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130301
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  • 51
    Electronic Resource
    Electronic Resource
    Continuous synchronous culture of Tetrahymena pyroformis (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 657-662 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Tetrahymena was continuously cultivated in a series of stirred tank reactors with recycle. By holding part of the reactor train at a higher temperature than the remainder a synchronizing influence was introduced into the cells' environment. The system resulted in division occurring preferentially in a small contiguous group of the reactors, this effect being observed in both the number of cells found in each reactor and also their size distribution.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130506
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  • 52
    Electronic Resource
    Electronic Resource
    Deep-tank culture of blue-green algae in H2O and D2O (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 779-793 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A 160-liter stainless steel algal growth tank has been constructed and has been used essentially continuously for over three years. Filamentous and unicellular blue-green algae as well as a photosynthetic bacterium have been cultured using both ordinary and heavy water (99.8 atom % 2H). By using a recycling technique, yields as high as 25 g/liter of 2H2O have been obtained.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130605
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  • 53
    Electronic Resource
    Electronic Resource
    The use of methane for production of bacterial protein (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 49-62 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Single cell protein production was studied in a mixed bacterial culture grown in methane using batch and continuous culture techniques. Overall productivity was found to be higher in the continuous culture which gave a maximum productivity value p = 0.15 g/l/h. Methane and oxygen were consumed in the relation 1 : 1.7. Yield coefficients for methane, oxygen, and ammonium chloride were YCH4 = 0.90, YO2 = 0.26, and YNH4Cl = 0.14. The crude protein content of the biomass was 71%.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130104
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  • 54
    Electronic Resource
    Electronic Resource
    Hydrocarbon fermentations using Candida lipolytica. I: Basic growth parameters for batch and continuous culture conditions (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 741-760 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Candida lipolytica (strain ATCC 8661) was grown on a simple defined medium with n-dodecane as sole carbon source under batch and continuous fermentation conditions. The composition of cellular material recovered from the fermentations, the oxygen demand of the cells, and the effect of operating conditions on cell growth were evaluated experimentally. These basic data are presented and discussed.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130603
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  • 55
    Electronic Resource
    Electronic Resource
    Response of continuous cultures to stimuli in glucose feed rate and dilution rate (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 815-824 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The response of continuous cultures of yeast was investigated following step disturbances in glucose feed rate and dilution rate.The responses of the culture to the stimuli were oscillatory. The oscillatory responses were explained in terms of cell synchrony which was induced by the step change. An understanding of continuous cultures to stimuli was made possible with an appreciation of the inherently oscillatory events occurring in the single cell cycle between one mitosis and the next. Step changes in glucose feed rate and dilution rate induced a partial synchrony, which enabled the inherently oscillatory behavior of the individual cells to be made observable in the culture as a whole.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130607
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    The response by microorganisms to steady-state growth in controlled concentrations of oxygen and glucose. II. Saccharomyces carlsbergensis (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 63-75 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The growth of Saccharomyces carlsbergensis in continuous culture has been studied when dissolved oxygen and glucose concentrations were held constant at a series of steady-state levels. Both oxygen and glucose controlled the degree of aerobic metabolism and of ethanolic fermentation. When the glucose uptake rate was low (between 1.2 and 2.8 mmoles per hour per gram of yeast) the relative distribution of glucose between ethanolic and aerobic fermentation was sensitive to oxygen: when dissolved oxygen was near to saturation, glucose metabolism was 0.98 aerobic; when dissolved oxygen was 0.01 saturated, 0.8 of intake glucose metabolism was by ethanolic fermentation. On the other hand when glucose intake was high (between 7.6 and 18.2 mmoles) metabolism was predominately by ethanolic fermentation even when dissolved oxygen concentration was at saturation. The extent, to which catabolism proceeded by an anaerobic or aerobic pathway, as judged by ethanol production, was controlled more by the uptake of glucose than of oxygen.
    Additional Material: 5 Tab.
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    URL: http://dx.doi.org/10.1002/bit.260130105
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    Quantitative ether extraction of acidic fermentation products (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 151-155 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130111
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    Preliminary experiments on spinning bacterial proteins into fibers (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 147-150 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130110
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  • 59
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    Effect of pH on the growth cycle of HeLa cells in batch suspension culture without oxygen control (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 471-492 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: HeLa cells have been cultured at different controlled pH levels in batch suspension culture with open gas phase. Continuous monitoring of the dissolved oxygen tension throughout the culture cycle reveals a characteristic pattern of variation which correlates with various aspects of growth and carbohydrate metabolism. The effect of pH, size, and physiological state of the inoculum on this pattern have been determined, and the results are discussed in terms of a theoretical respiratory rate equation.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260130403
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  • 60
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    The effects of glucose and oxygen on the cytochromes and metabolic activity of yeast batch cultures. I. Saccharomyces spp. (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 1-16 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Saccharomyces cerevisiae and Saccharomyces carlsbergensis were grown in batch culture with and without oxygen control.The concentrations of A-, B- and C-type cytochromes of both yeasts were dependent on the oxygen concentration during growth as well as on the initial glucose concentration of the growth medium. S. cerevisiae cytochromes were maximal after growth in low glucose and low oxygen; S. carlsbergensis cytochromes were maximal after growth in low glucose and high oxygen. Except when glucose was in very low concentration, its catabolism by S. carlsbergensis was directed predominantly towards ethanolic fermentation regardless of the oxygen concentration. Growth rate, total cell mass and yield were maximal, and anabolism was closely balanced with catabolism, when glucose and oxygen of S. carlsbergensis cultures were both high. Under these conditions neither catabolism, respiratory or ethanolic, nor glucose uptake were maximal.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130102
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  • 61
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    Utilization of cellulose from waste paper by Myrothecium verrucaria (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 77-97 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Extensive screening studies on cellulolytic bacteria and fungi led to the selection of Myrothecium verrucaria as the organism producing the maximum rate of protein biosynthesis from ball-milled newspaper. Studies in aerated stirred-jar fermentors were carried out to determine the conditions for maximum protein synthesis rate and maximum final protein concentration. The optimum aeration rate was 250 to 374 mM of oxygen at 300 to 400 rpm stirring rate. The pH optimum was broad, from 3.9 to 6.5. Urea at 0.03% and yeast autolysate at 0.1% stimulated growth rate and protein production. The maximum rate of protein biosynthesis and the maximum protein yield were 0.3 g/liter/day and 1.42 g/liter, respectively, from medium G3 with 4% ball-milled newspaper. The final product, obtained by evaporation of the total culture, was 33.7 g from one liter of medium which originally contained 40 g of ball-milled newspaper and 11.3 g of other dissolved materials. The protein content of this final product was 3.3 g, calculated from total organic N × 6.25 or 1.42 g calculated from the biuret method. Both the synthesis rate and the final cell yield are below those obtainable by growing Fungi Imperfecti, yeasts or bacteria on soluble materials such as glucose.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130106
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  • 62
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    Steady-state model for activated sludge with constant recycle sludge concentration (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 125-145 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In a previous report it was concluded that steady-state operation of completely mixed reactors for growth of heterogeneous microbial populations, i.e., activated sludge processes, was extremely difficult to attain if maintenance of a constant sludge recycle ratio, c, was required, and equations were devised in which the concentration of cells in the recycle, xR, rather than the recycle ratio, was constant. In this report the equations are developed and computational analysis shows the effect on substrate and cell concentrations in the reactor of operational variables such as inflowing feed concentration, hydraulic recycle ratio, recycle sludge concentration, dilution rate, and the biological “constants” μm, ks, and Y. The stabilizing effect of operating with constant xR on the dilute-out pattern is shown.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130109
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    Use of pH and pE measurements during methane biosynthesis (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 165-165 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130113
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    Preparation of a NAD(H)-polymer matrix showing coenzymic function of the bound pyridine nucleotide (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 393-398 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To a Sepharose gel the pyridine nucleotide NAD(H) has been bound using dicyclohexyl carbodiimide. In order to improve the steric availability of the nucleotide for added soluble enzymes such as dehydrogenases, a spacer molecule, ε-amino caproic acid, was inserted between the carbohydrate matrix and the nucleotide. The obtained preparation contained 56 μmoles NAD+/g dry polymer. The obtained matrix-bound NAD(H) was accepted as coenzyme by added lactate dehydrogenase. These preparations were still active after storage for several weeks at 4° C and could be used repeatedly without loss of activity. This represents the first necessary step taken in the preparation of compact closed systems consisting of “enzyme-coenzyme-coenzyme-regenerating enzyme” bound to individual polymer beads; such systems eliminate the need for continuous coenzyme addition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130306
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    Simulation of oxygen transfer in microbial slimes (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 569-579 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model based on diffusion mechanisms accounts for oxygen transfer from flowing nutrient medium into a film of organisms in slime. Profiles of dissolved oxygen concentration are generated at distances downstream from the start of the slime. In these studies, the nutrient medium was assumed rich, thus the rate of oxygen transport limited microbial respiration. Parameter sensitivity tests were performed for flow rate, oxygen concentration in the medium, and mass transfer coefficients.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260130410
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    Stability of immobilized β-galactosidase on prolonged storage (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 589-589 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130413
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    Controlled supply of trace amounts of oxygen in laboratory scale fermentations (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 619-628 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A detailed study of anaerobic yeast fermentations requires controlled addition of minor amounts of oxygen to the fermentor. A method for supplying small-scale fermentations with millimolar amounts of oxygen is described. The controlled addition is accomplished by diffusion of oxygen through silicone tubing carrying nitrogen to the fermentor. Sulfite values of the fermentation system are given for different gas velocities and lengths of silicone tubing. Two experiments are outlined in which this technique is applied and the possible energy yield from oxydative phosphorylation is discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130503
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    Effect of additives on mass transfer in turbine aeration (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 663-684 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Mass transfer coefficients and interfacial areas were determined for the aeration of aqueous solutions in a turbine agitated vessel. The mass transfer coefficients measured for water without additive and for sodium chloride solutions matched very well to measurements in the literature for air bubbles of the same diameter in free rise. Thus the only effect of agitation was to determine the bubble size which then in turn set the coefficient. Two surface active agents were studied: sodium dodecyl sulfate and Dow Corning Antifoam C. The rate of mass transfer increased with the former additive but decreased with the latter; however, the mass transfer coefficient was the exact same function of bubble diameter in both cases and the different rates are attributed to the quite different effects on interfacial area.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260130507
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    Masthead (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130601
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    Salting-out of enzymes with ammonium sulphate (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 713-718 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130513
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  • 71
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    A continuous flow automatically recording respirometer (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 721-739 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A respirometer suitable for continuous operation over extended periods of time is described. Oxygen is supplied to the culture by the electrolysis of water. The quantity of oxygen produced by electrolysis within any specified time interval is automatically printed on a tape. This record is combined with a continuous recording of the concentration of dissolved oxygen entering and leaving the reactor to produce a mass balance for oxygen in the system. Details on respirometer construction and operation are presented.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130602
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  • 72
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    Temperature relationship in continuous culture (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 795-813 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The steady-state and transient behavior of a chemostat-type continuous culture of Aerobacter aerogenes was investigated with special reference to temperature. Experimentally determined kinetic parameters of the fitted steady-state model were found to be strong functions of temperature. The transient response of the culture to a step change in temperature exhibited a dynamic lag whose magnitude depended on the nature and direction of step change.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130606
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    The cyclone column culture vessel for batch and continuous, synchronous or asynchronous, culture of microorganismsIssued as NRCC No. 12262. (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 865-876 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A simple inexpensive apparatus with a working volume of 10 liters of culture is described. Details of construction and procedures for operation of the cyclone column vessel are given. The vessel is self-contained, so that experimental parameters of temperature and aeration are individually controlled; homogeneous mixing and representative sampling of the culture, besides control of foam without need for antifoam, are obtained. The vessel may be used in single or multistage systems for aerobic or anaerobic cultivation of organisms in batch, chemostat, or phased cultures.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130610
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    Variability in cell yield for heterogeneous microbial populations of sewage origin grown on glucose (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 113-123 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Values of cell yield collected over a period of eight years for heterogeneous populations of sewage origin acclimated to glucose in both batch and continuous culture were subjected to statistical analysis. The cell yield for this sole source of carbon (glucose) ranged from 36 to 88 per cent in batch culture, and 32 to 69 per cent in continuous culture. Because experimental conditions were known and well defined, the variability in cell yield is attributable to the ecological variation inherent in a heterogeneous population. The data presented demonstrate the futility of attempts to define Y for such populations as a precise theoretical constant dependent upon thermodynamic properties of the substrate.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130108
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    Equipment for the automatic aseptic inoculation and sampling of microbial cultures (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 157-163 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Equipment has been designed and constructed for the automatic aseptic inoculation and sampling of microbial cultures. It enables fermentations to be started and samples to be taken round-the-clock, according to a predetermined program.The equipment is suitable for microbial processes on both a laboratory and a factory scale.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130112
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    The effects of glucose and oxygen on the cytochromes and metabolic activity of yeast batch cultures. II. Candida utilis (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 169-184 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Candida utilis was grown in batch culture with and without oxygen control. The concentrations of A-, B-, and C-type cytochromes were found to vary with the initial glucose concentration, with the dissolved oxygen concentration, and with time. A-type was the most sensitive. After glucose was essentially exhausted, the yeast catabolized ethanol, if it had been growing in a relatively low initial glucose concentration, or non-glucose carbohydrate, including some of that previously accumulated within the cell, if it had been growing in a high initial glucose concentration. This difference in metabolic pattern could explain why cytochrome derepression was initiated soon after glucose uptake ceased only if initial glucose had been relatively low. The effects of glucose and dissolved oxygen concentrations on yeast cytochromes and respiratory activity are discussed.
    Additional Material: 7 Tab.
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    URL: http://dx.doi.org/10.1002/bit.260130202
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    Conversion of 5′xanthylic acid to guanine and guanine nucleotides by a mutant of Brevibacterium ammoniagenesThis is Part XXXV of the series of reports entitled “Production of Nucleic Acid-Related Substances by Fermentative Processes.” (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 229-240 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A decoyinine resistant, KY 13501, isolated after nitrosoguanidine treatment from Brevibacterium ammoniagenes ATCC 6872 converted 5′XMP added in fermentation media to guanine derivatives and accumulated them in the media. The converted substances were identified as guanine, 5′GMP, 5′GDP, and 5′GTP. The conditions for the conversion were examined and the following points were clarified. (1) Very low concentration of manganese ion (Mn2+) showed profound effects on the conversion and the excessive amounts of the ion severely repressed the conversion. (2) Under limitation of Mn2+, 5′XMP was converted most efficiently when added at inoculation time. (3) The inhibition of the conversion by excessive amount of Mn2+ was completely released by addition of a surface activating agent, polyoxyethylene stearylamine. (4) For the conversion, it was essential to maintain pH of the media at 7.5 to 8.0 and supply ammonium ion.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260130206
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  • 78
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    Growth models of cultures with two liquid phases. V. Substrate dissolved in dispersed phase - experimental observations (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 241-256 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effects of inoculum size, dispersed phase volume and substrate concentration on the batch growth of Candida lipolytica are investigated in a model system composed of n-hexadecane dissolved in dewaxed gas oil. Tabular values and parameters are presented for 16 different experiments. All of the batch growth curves exhibited a linear growth region with the length of the region ranging from 1.5 to 9.5 hours. The rate of linear growth varied both with change in dispersed phase volume and initial dispersed phase substrate concentration. A qualitative analysis of the results is presented and possible explanations for the observed linear growth rates are discussed.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/bit.260130207
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    Control of culture mass in a chemostat (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 335-336 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130215
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    Masthead (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130101
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    A mechanistic study of oxygen transfer in aqueous systems (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 271-292 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Oxygen transfer coefficients were evaluated for a 14-liter stirred tank fermentor equipped with an oxygen probe, employing elemental copper adsorbed on a weakly basic anion-exchange resin as a solid phase oxygen acceptor. The use of a solid phase oxygen acceptor allowed evaluation of mass transfer resistances associated with the solid phase, and the effect of an oxygen adsorbing solid phase on the overall oxygen transport system, portions of the oxygen transfer process that are neglected by the conventional sulfite oxidation method commonly employed. It was concluded from the data obtained that a transport pathway involving transfer of oxygen to particles present near the air-water interface was a significant oxygen transport pathway for the system studied. Oxygen probe measurements performed on the bulk liquid did not recognize this pathway, suggesting that data taken on biological systems by use of techniques involving oxygen concentration measurements in the bulk liquid may not give the true oxygen absorbing capacity of a system.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130209
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  • 82
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    Effect of sludge flocs on the aeration performance of suction-impellers (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 323-330 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The authors have investigated a special aspect of the transfer of oxygen: the aeration performance of small-scale suction-impellers in a suspension of activated sludge floes and a performance comparison with clear water. The principle of the impellers is, that in order to disperse air bubbles into the aforementioned liquids, all that we need do is a simple stirring. Due to the impellers the authors could not show a reduction of the oxygen transfer coefficient in the presence of sludge flocs. Former comparative studies of oxygen transfer, using a fixed orifice, did show a reduction in the presence of sludge flocs. Therefore, it seems probable that the effect of activated sludge flocs on the transfer coefficient is linked with the manner in which air is dispersed, i.e., depends on whether an orifice is fixed or moved. The experimental results allow presumption that by developing a high intensity of shear near the location where air bubbles are produced, we are able to minimize the effect of sludge flocs on the process of bubble formation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130213
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  • 83
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    Chemical and biological aspects of a new family of phosphorus-containing antibioticsThis paper was presented as part of the Symposium on New pathways and Structures, Division of Microbial Chemistry and Technology, 160th National Meeting of the American Chemical Society, Chicago, Illinois, September 1970. (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 399-407 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The chemical, physical, and biological properties of a group of phosphorus-containing antibiotics are reviewed. Included in this family of antibiotics are the following compounds or mixtures of compounds: diumycin, macarbomycin, moenomycin, prasinomycin, 803GRP, 11,837RP, and 19,402RP. Among the aspects discussed are: antimicrobial activity in vitro, long duration of activity, toxicity, use in animal nutrition, cross resistance, mode of action, chemical and physical properties, and degradation studies.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130307
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  • 84
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    Xanthan biopolymer production at increase concentration by pH controlPresented at the 158th National Meeting of the American Chemical Society, Division of Microbial Chemistry and Technology, New York, N.Y., September 7-12, 1969. (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 381-391 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Efficient production of xanthan gum by fermentation with Xanthomonas campestris NRRL B-1459 can be accomplished at concentrations of xanthan in the fermented broth 〉 3%. This level of more than twice that previously attained by us results from continuously controlling the fermentation pH with alkali. Only a slight decrease in fermentation rate and yield occurs. When ammonia is used for pH control, cell production more than doubles and fermentation time is shortened. However, xanthan yield is decreased by the diversion of additional sugar to growth.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130305
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  • 85
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    Effect of shear on the death of two strains of mammalian tissue cellsThe paper was presented at the 160th National Meeting of the American Chemical Society. (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 409-418 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This study reports some findings on the death of mammalian cells occurring from fluid dynamic effects when they are pumped through capillaries. The cell strains used were human HeLa S3 and mouse L929, grown in monolayer culture. Cells were harvested and suspensions were pumped through various lengths and diameters of stainless steel capillary tubing. Viability of the cells was assayed by the dye exclusion test. Cell deaths occurred and could be correlated with either average wall shear or power dissipation within the capillary tube. L929 cells were found to be more sensitive than HeLa S3 cells at all shear rates tested.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130308
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  • 86
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    Spectrophotometric methods for monitoring the microbial transformation of steroids. II. Absorbance ratio spectrophotometric determination of per cent conversion of 9α-fluoro-16α-hydroxyhydrocortisone to 9α-fluoro-16α-hydroxyprednisolone (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 561-567 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A process method has been developed for estimating rapidly the conversion of 9α-fluoro-16α-hydroxyhydrocortisone to 9α-fluoro-16α-hydroxyprednisolone in fermentation broths. This allows frequent analyses of samples during the fermentation cycle. The absorbance ratio determination of conversion of the steroids is based on the measurement of the absorbance of aqueous steroid borate complexes at 241.5 mμ and 271 mμ.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130409
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  • 87
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    Masthead (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130501
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  • 88
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    Electrochemical measurements with glucose oxidase immobilized in polyacrylamide gel: Constant current voltametry (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 629-639 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Constant current voltametry was shown to be a suitable method for evaluation of electrodes containing immobilized oxidative enzymes as catalysts. The half-cell potential for the oxdidation of D-glucose at constant pH was measured at a series of constant dc currents, using glucose oxidase immobilized in a polyacrylamide gel-platinum gauze matrix as catalyst. Over the range studied the potential versus current data were linear and could be extrapolated to give the open-circuit half-cell potential at zero current. The difference between the measured potential and the open-circuit potential at a constant current was indicative of the loss in useful voltage due to concentration gradients within or adjacent to the enzyme electrode assembly. The relationship between the open-circuit potential and the pH of the reaction mixture was linear with a slope of -0.056, in good agreement with the predicted slope of -0.061.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130504
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  • 89
    Electronic Resource
    Electronic Resource
    Masthead (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971) 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130201
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  • 90
    Electronic Resource
    Electronic Resource
    Release of enzymes from bakers' yeast by disruption in an industrial homogenizer (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 549-560 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The rates of release of 7 enzymes from bakers' yeast have been measured. The disruption process did not cause loss of activity of these enzymes. The various operating pressures, temperatures, and initial yeast concentrations used did not affect the rates of enzyme release relative to protein release. The release of acid phosphatase and invertase was faster than the overall protein release. Alcohol, glucose-6-phosphate, and 6-phosphogluconate dehydrogenases were released slightly faster or at the same rate as the overall protein and alkaline phosphatase and fumarase were released more slowly. These observations correlate well with the reported locations of these enzymes in the yeast cell.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130408
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  • 91
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    Electronic Resource
    Comments on oxygen transfer within a mold pellet (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 583-588 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130412
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  • 92
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    Electronic Resource
    Oxygen mass transfer and oxygen respiration rate measurements utilizing fast response oxygen electrodes (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 599-618 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Oxygen transfer coefficient and oxygen respiration rate measurements in stirred tank reactors or fermentors have been carried out utilizing currently available dissolved oxygen electrodes. Techniques based on previously derived theory1 have been put to experimental tests and found to adequately describe the oxygen transfer phenomena observed in air-water systems and a fermenting broth.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130502
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  • 93
    Electronic Resource
    Electronic Resource
    A suspended-sludge-on-solid reactor: A new system for the activated sludge process (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 911-917 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130613
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  • 94
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    Preparation of L(+) β-hydroxyisobutyric acid by bacterial oxidation of isobutyric acidThis paper was presented at the 158th National Meeting of the American Chemical Society, New York, N. Y., Septermber 1969. (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 203-214 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A process for the bacterial oxidation of isobutyric acid to L(+) β-hydroxyisobutyric acid has been developed. The strain of Pseudomonas putida (ATCC 21244) used in this fermentation was isolated from local soil. The process was carried out in a 15-liter fermentor over a period of 70 hr and produced L(+) β-hydroxyisobutyric acid in conversions as high as 48%. Hydroxylation of the methyl group of isobutyric acid has special interest because it is difficult to perform chemically. The useful chemical syntheses of β-hydroxyisobutyric acid available at present do not start with isobutyric acid and are not stereospecific.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130204
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  • 95
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    Electronic Resource
    A mathematical model for RNA bacteriophage production in batch culture (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 257-270 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The interaction between male-specific RNA phages and bacterial cells as well as the complete life cycle of RNA phages in the host cells are complicated phenomena. In this study, a mathematical model is proposed to describe the kinetics of RNA phage production in batch culture. The model consists of several important considerations: (1) adsorption and desorption of phages on cell pili, (2) injection and transport of viral RNA, (3) viral protein synthesis, (4) phage maturation, and (5) cell lysis.Experimental data of MS2 RNA phage production in E. coli C 300o bacteria culture were used to evaiuate the model parameters. Reasonably good fit was obtained between the model and one set of data. However, simulation study based on the estimated parameter values revealed a discrepancy between experimental observation and model prediction. It seems that variation both in F-piliation and in the competence of cells to be infected by phages through different phasae of growth must be taken into account in order to make the model useful.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130208
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  • 96
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    Improved medium for saprophytic production of ergot alkaloids by Claviceps purpurea (Fr.) Tul. (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 331-334 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Studies were undertaken on the production of ergot alkaloids in saprophytic culture employing two strains of C. purpurea. In an attempt to improve the yield of the alkaloids and to develop a cheaper medium, the commonly used carbohydrate source, mannitol, was replaced with different types of starches and starchy materials as these are comparatively much cheaper than mannitol. Results indicated that, in stationary cultures, certain starches enhanced the yield greatly, while in shaker cultures starches could replace mannitol for equivalent yields.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130214
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  • 97
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    Hydrocarbon uptake by microorganisms - a supplementary study (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 691-695 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130509
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  • 98
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    Hysteresis in dynamic enzyme models (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 697-701 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130510
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  • 99
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    Electronic Resource
    Steroid esterase bound to porous glass beads (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 709-711 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130512
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  • 100
    Electronic Resource
    Electronic Resource
    Modification of a fermentor for pressurized fermentation (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 13 (1971), S. 703-707 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260130511
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