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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 7-17 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung In dieser Arbeit werden einige Arten von Optima eines Vektoroptimierungsproblems untersucht. Es handelt sich dabei um minimale, schwach minimale, stark minimale und eigentlich minimale Lösungen. Für diese Optimalitätsbegriffe werden verschiedene Optimalitätsbedingungen vorgestellt, die sich durch Skalarisierung ergeben. Außerdem wird auf einige numerische Aspekte eingegangen.
    Notizen: Summary In this paper several kinds of optima of a vector optimization problem are investigated; these are minimal, weakly minimal, strongly minimal and properly minimal solutions. For these optima various optimality conditions resulting from a scalarization approach are presented. Furthermore some numerical aspects are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 39-42 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Summary Two pro rata warranty models are considered in which the renewal costs during the warranty period depend on the time of failure. In the first model replacements or minimal repairs may be carried out during a fixed warranty period. In the second model the warranty for replaced items is renewed. For both models the expected cost per warranty cycle and the mean cycle length are determined.
    Notizen: Zusammenfassung Behandelt wird ein allgemeines Modell, bei dem die Erneuerungskosten bei einem Ausfall in einem Garantieintervall vom Ausfallzeitpunkt abhängen. Dabei werden 2 Fälle untersucht: 1) Die bereits verstrichene Garantiezeit wird angerechnet. Dabei werden vollständige bzw. minimale Garantiereparaturen durchgeführt. 2) Unter Zugrundlegung von vollständigen Reparaturerneuerungen wird auf jede Reparatur wieder die volle Garantiezeitw gewährt. Für beide Modelle werden die mittleren Erneuerungskosten pro Garantiezyklus sowie die mittlere Zyklenlänge berechnet.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 58-59 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 61-62 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 101-109 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung In diesem Beitrag wird das Problem der rationalen Betriebsführung des Lago Maggiore (eines Mehrzweckreservoirs in Norditalien) betrachtet. Zuerst wird die historische Betriebsführung analysiert, und es wird aufgezeigt, warum die Benutzer des unteren Teils des Sees nicht mit den Benutzern des oberen Teils kooperieren. Daraufhin wird die beste nicht-kooperative Lösung ermittelt und bewiesen, daß sie gegenüber der historischen dominant ist. Schließlich wird die beste kooperative Lösung bestimmt und mit der nicht-kooperativen Lösung verglichen. Wie üblich in Bewirtschaftungsproblemen natürlicher Ressourcen ist der Preis einer derartigen Nicht-Kooperation sehr hoch. Die Untersuchung zeigt ebenfalls einige einfache Vorschläge für eine Gesamtoptimalität und zur Konfliktauflösung auf.
    Notizen: Summary The problem of the rational management of Lake Maggiore (a multipurpose reservoir in Northern Italy), is considered in this paper. First, the historical management is analyzed and it is shown why the downstream users do not cooperate with the upstream users of the lake. Then the best non-cooperative solution is found and proved to be quite superior to the historical one. Finally, the best cooperative solution is obtained and compared with the non-cooperative one. The price of such non-cooperation is very high, as usually in natural resources management problems. The analysis also points out some simple suggestions for overall optimality and conflict resolution.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 127-128 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 153-164 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Summary This paper deals with an operational search game in military area. One side is interested in getting an allocation of its units inside a given inhomogeneous regionG. The other side wants to allocate its search effortT uponG. The solution takes into account the visibility and operational values of the subregions ofG. Of main interest is how the results depend on the search timeT. The relationship to search theory is also discussed. We refer to some open and extended problems, too.
    Notizen: Zusammenfassung Die Arbeit behandelt ein operationelles Suchspiel im militärischen Bereich, wobei eine Seite eine Aufteilung ihrer Einheiten in einem gegebenen inhomogenen GebietG vornimmt, die andere ihre SuchkapazitätT aufG verteilt. In die Lösung gehen die Einsehbarkeit und die operationeile Bedeutung der Teilgebiete vonG ein. Von besonderem Interesse sind die Abhängigkeit der Ergebnisse von der Suchzeit und der Zusammenhang mit der Suchtheorie. Auf offene und weiterführende Fragen wird hingewiesen.
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 187-188 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 189-189 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 208-208 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 11
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 209-215 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Bedienungssysteme mit wiederholten Versuchen sind von großem praktischen Nutzen bei der Bemessung von Vermittlungseinrichtungen und Computersystemen. Das Modell, das in dieser Arbeit vorgestellt wird, berücksichtigt nicht nur Wiederholungen nach vorangegangener Blockierung, sondern auch die Rückkopplungseffekte aller Arten von Fehlern, die beim Aufbau einer Verbindung auftreten können. Um die charakteristischen Größen des zugrundeliegenden Warteschlangenprozesses zu bestimmen, wird ein semi-regenerativer Ansatz gewählt.
    Notizen: Summary Queueing systems with repeated attempts have wide practical use in designing switching networks and computer systems. The model presented in this paper not only takes into account repetitions by congestion but also considers the feedback effects from all types of failures in establishing a connection. A semi-regenerative analysis is applied in order to determine the characteristics of the underlying queueing process.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 225-236 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Summary The budgetary laws in the Federal Republic of Germany require that large items of public expenditure be subject to prior cost-benefit analysis. This paper presents a cost-benefit method suitable for the analysis of urban public transport projects which is presently being tested. The methodical concept, which combines various aspects of differing forms of analysis, is described. The areas of conflict arising between practical and theoretical considerations are made clear and the experience gained so far with the concept is illustrated with examples.
    Notizen: Zusammenfassung Für größere Investitionsvorhaben der öffentlichen Hand sind nach den Haushaltsgesetzen des Bundes und der Länder Nutzen-Kosten-Untersuchungen durchzuführen [1]. In dem Beitrag wird ein entsprechendes Verfahren vorgestellt, das zur Beurteilung von Investitionsvorhaben des öffentlichen Personennahverkehrs entwickelt wurde und sich derzeit in der Erprobung befindet. Der Beitrag beschreibt das methodische Konzept des Bewertungsverfahrens, das eine Integration der verschiedenen Verfahren von Nutzen-Kosten-Untersuchungen beinhaltet. Konfliktbereiche zwischen methodisch-wissenschaftlichem Anspruch und dem Zwang zu praktikablen Verfahrensweisen werden aufgezeigt. Bisherige Anwendungserfahrungen werden an Beispielen dargelegt.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 237-248 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Mit fast allen Unternehmungen in Bayern, die OR-Methoden anwenden, wurden strukturierte Interviews durchgeführt. Der Schwerpunkt lag bei diesen Interviews auf den situativen Bedingungen, unter denen OR-Prozesse stattgefunden hatten. Diese Bedingungen sind in ihrer Gesamtheit geeignet, Scenarien für OR-Prozesse in Unternehmungen zu beschreiben. In den untersuchten Unternehmungen wurden höchst unterschiedliche Scenarien festgestellt. Das Muster für die Integration des OR in Management-Prozesse wird als zentraler Aspekt herangezogen, um drei typische Scenarien für OR-Prozesse herauszuarbeiten.
    Notizen: Summary The authors have conducted structured interviews with almost all business firms in a major area of Germany that apply OR-methods. The focus of these interviews was placed on the situational conditions under which OR-processes were run. These conditions, when taken as a whole, are suitable to describe the scenarios for OR-processes in business firms. The scenarios of the firms surveyed differ to a great extent. Nevertheless, the integration pattern of OR into management processes is obviously a key aspect, useful for elaborating three distinctive scenarios for OR-processes.
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 250-250 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 15
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 252-254 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 16
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 19-26 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Im Mittelpunkt dieser Arbeit steht die Unterklasse der 1-konvexenn-Personen-Spiele. Es stellt sich heraus, daß ein 1-konvexesn-Personen-Spiel durch die Struktur des Kerns charakterisiert werden kann und sein Nucleolus im Gravitätszentrum des Kerns liegt. Unter Benutzung der Formel für den Nucleolus wird gezeigt, daß für 1-konvexe Spiele der Durchschnitt von (Pre-)Kernel und Kern aus einem eindeutigen Punkt besteht. Allerdings kann der (Pre-)Kernel auch Punkte außerhalb des Kerns enthalten. Deshalb fällt die Verhandlungsmenge des 1-konvexenn-Personen-Spiels nicht notwendigerweise mit dem Kern zusammen, und der Teil der Verhandlungsmenge, der außerhalb des Kerns liegt, braucht sogar nicht mit dem Kern zusammenzuhängen. Zudem wird eine Einteilung der Klasse der 1-konvexen Spiele gegeben, die einen “großen” Kern besitzen.
    Notizen: Summary The subclass of 1-convexn-person games is central in this paper. It turns out that an 1-convexn-person game can be characterized by the structure of the core and that its nucleolus lies in the center of gravity of the core. Using the formula for the nucleolus, it is shown that for 1-convex games the intersection of the (pre-) kernel with the core consists of a unique point. Nevertheless, the (pre-)kernel may contain points outside the core. Hence, the bargaining set of an 1-convexn-person game not necessarily coincides with the core and the part of the bargaining set outside the core may even be disconnected with the core. Furthermore, the class of 1-convex games which possess a “large” core, is classified.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 51-56 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 43-50 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Zweck des vorliegendes Aufsatzes ist es, ein optimales Instandhaltungsmodell von Kamien und Schwartz [8] durch Einbeziehung der Produktionsrate als zusätzliche Steuervariable zu erweitern. Zwei Modelle werden untersucht: beim ersten handelt es sich um die optimale Aufteilung von vorbeugenden Instandhaltungsmaßnahmen an einer Maschine und Produktion, während im zweiten Fall die Aktivitäten unabhängig voneinander simultan ausübbar sind. Unter Benützung des Pontrjaginschen Maximumprinzips wird u. a. gezeigt, daß bei optimaler Einsatzdauer der Maschine die optimale Produktionsrate mit dem Alter der Anlage monoton steigt, während die optimale Rate der Instandhaltung abnimmt. Unter den gesetzten Modellannahmen erweist es sich also etwa alssuboptimal, einer Abnahme der Maschinenzuverlässigkeit infolge gesteigerter Produktion durch erhöhte Aufwendungen für die Instandhaltung zu begegnen.
    Notizen: Summary The purpose of the following paper is to extend the optimal maintenance model of Kamien and Schwartz [8] by including the production rate as an additional control variable. Two models are considered: the first model deals with the optimal allocation of preventive maintenance of a machine and production, whereas in the second case both activities may be carried out independently and simultaneously. Using the maximum principle it is shown that for the optimal life time of the machine the optimal production rate increases monotonically with the age of the machine, whereas the optimal maintenance rate is decreasing. Thus, under the assumptions made it is, e.g.,not optimal to counteract a decrease in the machine's survival probability arising from an increasing production rate by a higher maintenance rate.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 81-90 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Summary The stochastic programming problem is described as a stochastic multiple criteria model (SMCM). The solution found by the SMCM has to be efficient. The chance constrained programming model and the two stage programming model derived from suitable defined SMCM satisfy this condition. Another solution approach is presented which determines efficient solutions, too. Furthermore a solution method for this approach is constructed.
    Notizen: Zusammenfassung Die stochastische lineare Optimierungsaufgabe wird als stochastisches mehrfaches Zielsetzungsmodell (SMZM) dargestellt. Es wird verlangt, daß die mit Hilfe eines SMZM ermittelte Lösung effizient ist. Das Modell mit Wahrscheinlichkeitsrestriktionen und das Kompensationsmodell, die aus geeignet definierten SMZM hergeleitet werden, erfüllen diese Forderung. Zu einem weiteren Lösungsansatz, der ebenfalls effiziente Lösung determiniert, wird unter der Voraussetzung spezieller Verteilungsannahmen an die Zufallsvariablen ein Lösungsalgorithmus konstruiert.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 111-114 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Um die Kosten eines gemieteten Datennetzes zu senken, kann ein Teilnehmer Multiplexer vom Netzeigner mieten. Diese liegen zwischen den Terminals und der zugehörigen Vermittlungsstelle und können in Serie geschaltet sein. Ein Verfahren zur Optimierung der Standorte solcher Multiplexer wird hier dargestellt.
    Notizen: Summary In order to reduce the costs of using (or leasing) a data telecommunication network, a subscriber can lease multiplexers from the network carrier. These multiplexers are placed between the subscriber terminals and the corresponding exchange, several multiplexers being able to be connected in series. An optimization method for the location of such multiplexers is presented here.
    Materialart: Digitale Medien
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  • 21
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 143-151 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Diese Arbeit befaßt sich mit diskreten Markoffschen Entscheidungsmodellen mit endlichen Zustands- und Aktionsräumen. Ein lineares Programm wird entwickelt für die Berechnung von optimalen Politiken über den ganzen Bereich des Diskontierungsfaktors. Anschließend wird ein Verfahren angegeben für die Bestimmung einer Blackwell-optimalen Politik.
    Notizen: Summary This paper deals with a finite-state, finiteaction discrete-time Markov decision model. A linear programming procedure is developed for the computation of optimal policies over the entire range of the discount factor. Furthermore, a procedure is presented for the computation of a Blackwell optimal policy.
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  • 22
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 190-194 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 23
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 216-216 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 24
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 217-224 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Summary This paper deals with models concerning the use of a limited number of missiles in a sea or air-sea battle. The central question is about how a smaller but qualitatively superior unit of surface vessels or aircraft ought to allocate its missiles upon a larger unit which is distributed in depth. Mathematical formulation and solution of these problems takes place in the framework of stochastic dynamic programming.
    Notizen: Zusammenfassung Es werden Modelle zum Einsatz von Flugkörpern im See- bzw. See-Luftgefecht vorgestellt. Im Vordergrund steht die Frage, wie ein quantitativ unterlegener, aber qualitativ überlegener Verband von Überwasserstreitkräften oder Flugzeugen seine Flugkörper gegen einen größeren, in der Tiefe gestaffelten Verband einsetzt. Die mathematische Formulierung und Beantwortung der Fragen erfolgt im Rahmen der stochastischen dynamischen Programmierung.
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  • 25
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 250-250 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 26
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 252-252 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 27
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Summary Even if the type of inventory differs from the normal situation usually described with respect to kind of stock, organizational form or stock management, it is usually possible to carry out a sample inventory using suitable procedure variants that fulfills the usual conditions. The following considerations are based on experiences with several inventories for single objects in the production area. The storing process is done in a semihazard manner. The amount-oriented stock management is a condition for steering the production and is extraordinarily reliable.
    Notizen: Zusammenfassung Auch wenn der Typ eines Lagers nach Vorratsart, Organisationsform oder Bestandsführung von der üblicherweise beschriebenen Normalsituation abweicht, ist es meist durch geeignete Verfahrensvarianten möglich, eine den Anforderungen entsprechende Stichprobeninventur durchzuführen. Den folgenden Überlegungen liegen Erfahrungen mit mehreren Lägern für Einzelgegenstände im Produktionsbereich zugrunde. Die Lagerung erfolgt halb-chaotisch. Die mengenmäßige Bestandsführung ist Voraussetzung für die Produktionssteuerung und daher außerordentlich zuverlässig.
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  • 28
    Digitale Medien
    Digitale Medien
    Springer
    OR spectrum 7 (1985), S. 251-251 
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Engineering with computers 1 (1985), S. 27-37 
    ISSN: 1435-5663
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Maschinenbau , Technik allgemein
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 30
    Digitale Medien
    Digitale Medien
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    Empirical economics 10 (1985), S. 27-35 
    ISSN: 1435-8921
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract This paper estimates and tests a model of the demand for money function, which uses the public's expectations of future inflation as a proxy of the opportunity cost of holding money. The hallmark of the paper is that expectations are rational inMuth sense. The cross-equation rational expectations restrictions are derived and then tested, using quarterly Greek data of the high inflation period 1973I to 1981 IV. The paper concludes that the evidence is consistent with the rational expectations assumption and supports the adopted specification of the money demand function.
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  • 31
    ISSN: 1435-8921
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Summary In this paper we use information theory to assess the indicator quality, in the Austrian economy, of various monetary aggregates. In addition to simple sum aggregates we utilise discrete Divisia quantity indices, which have reputable aggregation and statistical attributes. Without using a particular macro-economic model we estimate the expected information gains, with respect to various policy objectives like inflation, real growth and unemployment, derived from monitoring various monetary aggregates. Finally, we compare the empirical results derived for Austria with those provided in earlier studies, using UK and United States data.
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  • 32
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    Empirical economics 10 (1985), S. 51-58 
    ISSN: 1435-8921
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract In this paper we test directly for the restrictions implied by rational expectations and structural neutrality. The tests are direct in the sense that they employ theLucas output equation father than the approximations to it, which replace the lagged output term by lagged monetary shocks, commonly considered in the literature. The direct approach is considered preferable because it avoids these ad hoc approximations and saves significantly on degrees of freedom. The latter permits us to pursue a fully nested testing procedure, which was not possible in earlier work employing postwar U.K. annual data. The main result is that the rational expectations restrictions are not accepted.
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  • 33
    Digitale Medien
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    Empirical economics 10 (1985), S. 65-89 
    ISSN: 1435-8921
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract This study utilizes an econometric model of equilibrium in the U.S. livestock and feedgrain markets to investigate a number of questions of economic methodology and policy. Both nonlinear consumer demand equations that obey the constraints of neoclassical demand theory and a model of supply are used. This approach allows for the measurement of the effects on consumer welfare of actual government policies. In particular, the model is employed to analyze the welfare effects of an actual policy situation — the sale of U.S. grain to the Soviet Union in the third quarter of 1972.
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  • 34
    Digitale Medien
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    Empirical economics 10 (1985), S. 103-120 
    ISSN: 1435-8921
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract The purpose of this paper is to test and estimate dynamic aggregated and disaggregated models of import demand with quarterly Finnish data. The main conclusions are that the log-linear functional form is preferable to the linear form and that there is empirical support in favor of estimation of import demand models in a disaggregated framework. On the whole, adjustment of Finnish imports of goods is relatively fast.
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  • 35
    Digitale Medien
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    Empirical economics 10 (1985), S. 59-64 
    ISSN: 1435-8921
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract This note discusses the slope coefficient of a linear regression of the rate of exchange rate depreciation on the interest differential. It is shown that the variance of the rationally expected rate of depreciation exceeds the variance of the foreign exchange risk premium if that coefficient exceeds the value 0.5 (and vice versa). Empirical results indicating that the variance of the risk Premium typically exceeds the variance of the rationally expected rate of depreciation are presented.
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  • 36
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    Empirical economics 10 (1985), S. 125-129 
    ISSN: 1435-8921
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract The hypothesis that the greater a firm's involvement in exports, the greater will be that firm's demand for liquid assets, is empirically tested in this paper. The results are supportive of the hypothesis. In addition it was found that firms owned by labor cooperatives have lower demand for liquid assets than other firms.
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  • 37
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary The sonic velocity of preoriented PET fibres as a function of temperature was measured in dependence on the degree of orientation, stress applied to the fibres, and heating rate. The results reflect the structural and orientation changes which take place in the range of and above the glass transition temperature.
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  • 38
    Digitale Medien
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    Polymer bulletin 13 (1985), S. 29-33 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Natural rubber vulcanizates with high primary molecular weight were prepared by mixing raw rubber and dicumyl peroxide in benzene followed by freeze-drying. The stress-strain properties of these vulcanizates were quite different from those prepared by conventional mastication method. The important characteristics of these vulcanizates is high tensile modulus, high tensile strength, large hysteresis loss, and higher degree of strain-induced crystallization. The difference in the stress-strain behavior between these rubbers and conventional vulcanizates are discussed from the standpoint of the network structure.
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  • 39
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
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  • 40
    Digitale Medien
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    Polymer bulletin 13 (1985), S. 91-96 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary A modification of a theoretical model for the determination of the number average molecular weight between crosslinks, ¯Mc, is presented for the case of multifunctional junction functionalities in highly crosslinked, macromolecular systems.
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  • 41
    Digitale Medien
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    Polymer bulletin 13 (1985), S. 97-102 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Three-arm star polyisobutylenes carrying tert.-chlorine end groups and a phenyl ring at the center of the star (see formula II in the Introduction) have been prepared by a continuous polymerization process. Thus into a stirred glass reactor were fed continuously a mixed feed of monomer plus trinifer (TCC) and a separate feed of BCl3 coinitiator in methyl chloride solvent at −40°C, and the product plus unreacted ingredients were removed continuously. Stationary conditions were maintained by keeping the rates of input and output (i.e., volumes) equal and constant. After a short induction phase (∼2–3 residence times) telechelic polymers of essentially theoretical number average end functionalities (¯Fn=3.0+0.1), close to theoretical molecular weights (¯Mn) and molecular weight distributions were obtained. The polymerization kinetics are discussed and compared to that of an earlier semicontinuous process used for the routine synthesis of telechelic polyisobutylenes.
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  • 42
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary A new series of thermotropic liquid crystalline poly(β-thioester)s was prepared by a Michael-type polyaddition of α,ω-polymethylenedithiols of different length to a mesogenic diacrylate containing two bis(p-oxybenzoate) units symmetrically connected through a dodecamethylene segment. The thermotropic behaviour was studied by combined DSC and thermal-optical analyses. All the poly(β-thioester)s investigated exhibited quite unusual monotropic mesomorphism.
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  • 43
    Digitale Medien
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    Polymer bulletin 13 (1985), S. 163-169 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Composites of low-density polyethylene were prepared by the sorption of vinylic monomers and a photoinitiator into a polymer matrix, followed by UV irradiation. Gravimetric determinations showed that 2–4% incorporation of the polymer in the host matrix is possible by this method. Transmission and reflectance infrared spectra measurements showed that the vinylic polymer is lodged in the bulk of the polymer film with no surfacial deposition.
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  • 44
    Digitale Medien
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    Polymer bulletin 13 (1985), S. 193-193 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
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  • 45
    Digitale Medien
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    Polymer bulletin 13 (1985), S. 463-467 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Weight fraction activity coefficients (Ω1)∞ and interaction parameters x have been determined for seven different solvents in Polyarylate at three temperatures by the gas chromatographic method (inverse gas chromatography). Data have been used to calculate infinite dilution solubility parameters according to the method proposed by DiPaola-Baranyi and Guillet. The validity of the plots involved in the above mentioned method is also discussed.
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  • 46
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary 90 MHz-1H-NMR and 22.635 MHz-13C-NMR spectroscopy were used in a study of vinyl chloride-vinylidene chloride co-polymers. Triad sequence distribution of CCl2 and CHCl carbon was generated for these copolymers and compared to calculated distributions based on Bernoullian, first-order Markov and second-order Markov statistics. It was observed that for samples different in the conditions of preparation including commercial materials in each case different Markov models give the best fit in formally mathematical treatment without kinetic significance but with the aim of interpretation of physical and/or chemical properties of the copolymers. The 52–56 ppm region of the VC-VDC copolymer spectra is complicated by the superposition of the effects of tacticity, sequence distribution and the presence of both CH and CH2 carbons.
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  • 47
    Digitale Medien
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    Polymer bulletin 14 (1985), S. 265-270 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Two methods of the synthesis of tributyl ammonium derivatives of glycidyl methacrylate — ethylene dimethacrylate copolymers with various contents of the crosslinking agent were examined. While the two-step process which consists in a reaction with dibutyl amine followed by alkylation with butyl bromide gives products with up to 1.5 mmol/g of required groups, in the case of the single-step reaction of the epoxide group with tributyl amine the content does not exceed 0.4 mmol/g. The use of diamines for increasing the distance between the quaternary group and the polymer backbone does not yield a readily definable product, and cannor therefore become the method of choice.
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  • 48
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary A novel series of photoinitiators for cationic polymerization have been prepared which bear two and three photoactive triarylsulfonium groups in the same molecule. These compounds have been fully characterized by means of their UV and C-NMR spectra and liquid chromatography as well as by their elemental analyses. The multifunctional triarylsulfonium salts have been compared among themselves and against monofunctional triarylsulfonium salts in the photoinitiated cationic polymerization of dl-limonene dioxide.
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  • 49
    Digitale Medien
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    Polymer bulletin 14 (1985), S. 399-406 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary The miscibility of blends of poly(butylene terephthalate) and poly(bisphenol A-carbonate) was investigated using differential scanning calorimetry. Contrary to previously reported data, PBT and PC were found to be almost completely immiscible over the entire compostion range studied. The minor change in Tg's observed for samples quenched form the melt can be attributed to transesterification at elevated temperatures. The melting behavior and normalized enthalpy of fusion are somewhat dependent on composition but the behavior is erratic.
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  • 50
    Digitale Medien
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    Polymer bulletin 14 (1985), S. 417-423 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Two unsaturated ester-containing vinyl ethers, 2-vinyloxyethyl acrylate $$(\mathop 1\limits_ )$$ and sorbate $$(\mathop 2\limits_ )$$ , were polymerized by the hydrogen iodide/iodine (HI/I2) initiating system in toluene at −15 or −40°C, to give “living” polymers, having a very narrow molecular weight distribution (Mw/¯Mn=1.10–1.15) and crosslinkable via their pendant C=C double bonds. The number-average molecular weight of the polymers increased in direct proportion to conversion, and further increased on addition of a new monomer feed to a polymerized reaction mixture. According to 1H and 13C NMR structural analysis, the polymerization proceeds exclusively via the vinyloxyl group of the potentially bifunctional monomers without undesirable side reactions of the unsaturated ester pendants.
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  • 51
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary The radical copolymerization of methyl- and butyl methacrylates with an electrondonor monomer: N-(2-hydroxyethyl)-carbazolyl methacrylate and an electron-acceptor monomer: (β-hydroxyethyl)-3,5-dinitrobenzoyl-methacrylate respectively, in dioxane at 60°C was investigated. The reactivity ratios of the binary systems were computed by using the Kelen-Tüdös method. The azeothropic compositions were established according to the respective copolymerization diagrams.
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  • 52
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    Polymer bulletin 14 (1985), S. 461-468 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary The small-angle X-ray scattering curves of carboxy-telechelic polymers exhibit very strong scattering at the lowest angles which points to the presence of large aggregates in the samples. Beyond the position of the main scattering maximum, common to all ionomers, a faint modulation is observed at a position corresponding to a second diffraction order. These observations are discussed with respect to other data in the litterature.
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  • 53
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    Polymer bulletin 14 (1985), S. 477-477 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Materialart: Digitale Medien
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  • 54
    Digitale Medien
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    Polymer bulletin 14 (1985), S. 491-495 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Bulk polymerizations of L,L-lactide were conducted at 120 and 180°C, but mainly at 150°C. Magnesium oxide, ethoxide, acetate, stearate, and 2,4-pentane dionate were used as catalysts. Time conversion curves show that at least a temperature of 150°C and a reaction time of 72 h is required for maximum conversion. The highest yields (up to 96 %) were obtained with magnesium oxide. However, all initiators, in particular magnesium oxide, caused racemization which increased with reaction time and temperature. Polymerizations in solutions at temperatures around 100°C failed regardless of the solvent.
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  • 55
    Digitale Medien
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    Polymer bulletin 14 (1985), S. 497-502 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary L,L-lactide was polymerized in bulk at 120°C, 150 or 180°C by means of various metal oxides, carbonates or carboxylates. Yield, viscosities and optical rotation were measured and compared. Several catalysts enable a nearly complete conversion even at 120°C indicating rapid diffusion of the monomer in the solid reaction mixture. At 180°C only SnO and Sb2O3 proved to be useful catalyst, because they gave within 12 h yields 〉 80% along with an optical purity around 97%. Longer reaction times lead at 180°C to substantial racemization in all cases.
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  • 56
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary It is shown that i-butyl vinyl ether, tetrahydrofuran, epichlorhydrin and cyclohexene oxide, which undergo typically cationic polymerisation, are polymerised by UV-irradiation in the presence of diacetoxyiodobenzene or bis(trifluoroacetoxy)iodobenzene.
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  • 57
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    Polymer bulletin 14 (1985), S. 527-534 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary The preparation of high molecular weight nylon 4 with alkali metal pyrrolidonate catalysts, acyl initiators, and CO2 was studied. Isolated sodium pyrrolidonate and the appropriate amount of acyl initiator gave unusually high molecular weight nylon 4 (mw 〉200,000). The molecular weight-initiator concentration relationship indicates that acyl compounds play a dual role in the polymerization, acting both as initiators and scavengers for chain-terminating impurities. One potential chain terminator was identified as 4-aminobutyric acid. The high polymer molecular weights obtained in the presence of CO2 can also be explained by the scavenging of chain terminators by CO2. Determination of the number of growing chains, however, shows that CO2, unlike the acyl compounds, is not an initiator in nylon 4 polymerization.
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  • 58
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    Polymer bulletin 14 (1985), S. A3 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
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  • 59
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Nitrile rubber (NBR) was reinforced by poly(p-phenylene terephthalamide) (PPTA) with a coprecipitation method from a common solvent of them. PPTA was converted to N-sodium PPTA with sodium hydride in DMSO, forming homogeneous solution. DMF dissolves NBR. Both solutions were blended to form an isotropic solution. The precipitant was NBR reinforced by PPTA which was regenerated from N-sodium PPTA at coagulation as reported previously. The molecular composite thus obtained was mill-blended with poly(vinyl chloride) (PVC) in order to enhance solvent resistant property. The vulcanized composite of NBR/PVC reinforced by PPTA showed higher modulus, higher strength and more improved solvent resistance than the gum stock and the black stock of NBR/PVC. The properties of the molecular composite containing 5phr PPTA found approximately comparable to those of the black stock of NBR/PVC with 30–40phr ISAF carbon black.
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  • 60
    Digitale Medien
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    Polymer bulletin 13 (1985), S. 65-70 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Copolymers of 2-ethyl-2-oxazoline and phtalic anhydride without initiator in DMF at 60 °C were synthesized. The copolymers were statistical, rich in 2-ethyl-2-oxazo1ine. A partial hydrolisis of pendant groups -COCH2CH3 is observed. The composition and the hydrolisis degree of the copolymers was determined by 1H-NMR. A copolymerization scheme via zwitterion is proposed.
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  • 61
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    Polymer bulletin 13 (1985), S. 90-90 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
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  • 62
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary A R 401 Waters Assoc. differential refractometer has been modified to obtain the variation of refractive index increments, dn/dc, of polymer solutions at 633 nm. The introduced modifications were in the sample injection system and in the light source. The performance of the modified refractometer both with aqueous and organic solutions is analyzed. In order to localize a conformational transition in lysozyme, the dependence of dn/dc on temperature for lysozyme solutions in phosphate buffer is studied. Similarly, (dn/dc)k values for the ternary n-alkane/butanone/poly(dimethyl siloxane) systems over the whole composition range of the binary solvent mixtures are evaluated.
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  • 63
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    Polymer bulletin 13 (1985), S. 109-114 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Diblock copolymers of acetylene and styrene were prepared by treating Ti(OBu)4 with polystyryl lithium followed by reaction with acetylene. Reliable evidence for the formation of block copolymers was derived from dual radiotagging experiments.
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  • 64
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    Polymer bulletin 13 (1985), S. 123-130 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Poly (isobutylene-b-ethylene glycol) PIB-b-PEG diblock copolymers have been synthesized by reacting tolylene 2,4-diisocyanate-capped polyisobutylene with monohydroxyl-ended poly(ethylene glycol). The block copolymers form stable benzenewater emulsions and show surface activity decrease in interfacial surface tension, and existence of critical micelle concentration. Turbidimetry of the block copolymers indicates the expected wide range of solubility from nonpolar to polar solvents. The temperature dependence of the intrinsic viscosity of the block copolymers exhibits characteristic discontinuities. The intrinsic viscosity of the block copolymer as a function of solvent polarity was studied and the observations were explained as the sum of segment contributions based on the “segregated” conformation model. DSC also indicates microphase separation in the solid state due to segment incompatibility.
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  • 65
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary The nucleophilic substitution with C6H5SNa, at -30°C, is compared for five PVC samples with various contents of isotactic triads. The conversion curves consist of a very fast stage followed by a steady one. All the samples are found to behave in the same way except for the content of the structures involved in the fast period. This content is estimated by extrapolating the straight lines of the steady stages to zero time. The obtained values are found to be a linear function of the content of isotactic triads. The results, together with some earlier ones, allow for the content of the labile non-defect structures in PVC to be determined.
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  • 66
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    Polymer bulletin 13 (1985), S. 185-192 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Abstract The influence of non macroporous and macroporous supports on a test reaction is studied. t-BuOH reacts with tetra O-acetyl bromoglucose in presence of silver nitrate and a supported crown ether. Two reaction products are formed. Yield and selectivity are affected by the morphology of the support. The selectivity depends on the crosslinking degree. This dependence is explained by the rigidity of the matrix and by the variation of steric hindrance.
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  • 67
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    Polymer bulletin 14 (1985), S. 61-68 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary The influence of draw ratio on macroscopic and crystallographic density of polyethylene with different initial morphologies, has been investigated by solid-state extrusion. An initial drop followed by an increase in macroscopic density as a function of draw ratio has been observed. Since precision X-ray measurements of unit cell parameters showed no variation of crystallographic density, it was concluded that plastic deformation of polyethylene upon drawing proceeds with a decrease of the degree of crystallinity. This was confirmed by differential scanning calorimetry.
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  • 68
    Digitale Medien
    Digitale Medien
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    Polymer bulletin 14 (1985), S. 73-77 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary 2-lsopropenylquinoline has been synthesized, and anionic homopolymerization has been performed with n-butyllithium and with dibutylmagnesium, yielding polymers with high glass transition temperatures, with Mn ranging from 3700 to 210300. Molecular heterogeneities have been determined by GPC. Mw has been measured by light scattering. The glass transition temperature for infinite molecular weight is 475 K. The ceiling temperature, 367 K, was calculated from 1H-NMR spectra recorded from living poly-(2-isopropenylquinoline) at different temperatures. Two- and threeblock-copolymers have been obtained by initiating 2-isopropenylquinoline with living polybutadiene.
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  • 69
    Digitale Medien
    Digitale Medien
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    Polymer bulletin 14 (1985), S. 99-104 
    ISSN: 1436-2449
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Summary Densitometric conformational studies were made on poly(1-vinyl-2-pyrrolidone-co-maleic acid) in the presence of LiCl, NaCl, KCl, CaCl2, and MgCl2, in order to control ion-binding of the polyanion in dilute aqueous solution. Experimental verification of principal role of deprotonation in the conformational transition of the polyacid chains during titration is given. Correlation was found between the apparent molar volume of the copolymer and the ionic radius of the bound cation.
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  • 70
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 58-66 
    ISSN: 1435-1536
    Schlagwort(e): latex ; amphoteric ; ionogenic ; size ; polystyrene
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Amphoteric polystyrene latex colloids were prepared by the “emulsifier-free” emulsion polymerization of styrene. Two co-monomers, methacrylic acid (MA) (anionic) and dimethyl aminoethyl methacrylate (DMAM) (cationic) were used to promote the amphoteric nature of the resultant surfaces. Parameters such as particle size and the isoelectric point (IEP) were measured as a function of polymerization recipe. Particle size decreased with increasing initiator concentration according to the equation: log [d w]=−0.67 log [I] + 0.316 whered w is the weight average particle diameter andI is the concentration of initiator (potassium persulphate). The particle size also decreased with increasing temperature, increasing pH and addition of surfactant. Particle size was unaffected by the methacrylic acid content. The isoelectric point pH was decreased on decreasing initiator concentration and on increasing methacrylic acid content. The polymerization pathway was deduced to involve the cationic DMAM during the initiation phase and to involve the anionic MA as well as styrene, during the growth stage. A full polymerization pathway involving the formation of “oligomeric DMAM micelles” was postulated.
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  • 71
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 75-80 
    ISSN: 1435-1536
    Schlagwort(e): Flotation ; mobility ; contact angle ; selectivity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The following two cases of attachment of particles onto the “water-air” interface are considered: a) perfectly sliding three-phase contact, according to Nutt and b) three-phase contact of very strong hysteresis or detachment throught a “neck”. The corresponding expression relating the contact angle, mobility of the three-phase contact, the radius of the particles and the flotation selectivity parameter are obtained. Experimental data for the systems: for quartz-galena 10−5 M/1 solution of potassium ethylxanthogenate and for glass spheres 10−5 M/1 solution of dodcylamoniumchloride are presented. Particles in the range of radii from 10−5 to 10−5 cm are considered. The present study indicates a possibility to enhance flotation selectivity through the appropriate classification of initial material and/or collective concentrates, and separate flotation of the different size ranges. At some size ranges selectivity will be enhanced while at others the flotation process will be intensified.
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  • 72
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 783-790 
    ISSN: 1435-1536
    Schlagwort(e): Ultradrawn polyethylene ; storage modulus E' ; radiation dose ; radiation-induced scission
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract This paper is concerned with the temperature dependence of mechanical properties of ultradrawn polyethylene in terms of storage modulus E' and loss factor tanδ by the measurement of the complex dynamic tensile modulus over ranges of temperature from 20 to 140
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  • 73
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 799-803 
    ISSN: 1435-1536
    Schlagwort(e): Biopolymers ; thermoplastics ; dynamic modulus ; X-ray scattering ; mechanical anisotropy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Dynamic tensile modulus and X-ray scattering measurements were made for a series of bacterially produced poly-Β-hydroxybutyrate/Β-hydroxyvalerate (PHB/HV) random copolymers. The position of the primary relaxation is shifted to lower temperatures by increasing HV content and the material becomes generally softer. Drawn PHB/ 17% HV copolymer shows conventional mechanical anisotropy. Results are presented comparing the dynamic mechanical behaviour of isotropic PHB/HV with that of conventional thermoplastics such as polyethylene terephthalate, isotactic polypropylene and polyethylene.
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  • 74
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 812-817 
    ISSN: 1435-1536
    Schlagwort(e): Charge density ; polyacrylamide ; NMR ; DSC ; T g
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract New methods are suggested for the determination of the charge density of acrylamide/acrylate copolymers.13C nuclear magnetic resonance spectroscopy was used to determine the comonomer ratio by comparing the peak intensities of the methine carbon in acrylamide and acrylate monomers. Results were compared with those obtained by conductometric and potentiometric titration and were found to be in good agreement. Differential scanning calorimetry was employed to determine the glass transition temperatures (T g) of the copolymers. A master curve was established by plottingT g versus charge density of the copolymers previously determined by NMR and conductometric titration. Compositions of poly(acrylamide-co-acrylate) samples can thus be determined by measuring theT g and reading the percent composition directly from the master curve.
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  • 75
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 822-831 
    ISSN: 1435-1536
    Schlagwort(e): Polypropylene ; isothermal crystallization ; spherulite ; growth rate ; equilibrium melting temperature ; surface energy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The growth rate of isotactic polypropylene is deduced from microscopic observations during isothermal crystallizations. A change in the growth regime is observed at 138
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  • 76
    ISSN: 1435-1536
    Schlagwort(e): Energy distribution ; heterogeneous surface ; heat of adsorption ; zeolite
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Theε—θ function (energy level function) which represents surface heterogeneity was derived from theq—θ function (experimental heat function) in the case of reversible adsorption. The Langmuir equation was extended and applied to the procedure of calculations. An iterative calculation led to the most probableε—θ function by setting theq—θ function and adsorption temperature. As an example for actual cases, theε—θ function of Na-Y zeolite was calculated from theq—θ function obtained by the measurement of heats of adsorption of ammonia at 373 K. Theε—θ function thus derived seemed to be consistent with the positional distribution of sodium ions.
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  • 77
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 873-878 
    ISSN: 1435-1536
    Schlagwort(e): Dielectric measurements ; high pressure ; glass relaxation ; poly(vinyl acetate) ; poly(vinyl chloride)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Measurements of the complex relative permittivity of poly(vinyl acetate) from 35 °C to 190 °C and poly(vinyl chloride) from 90 °C to 150 °C in the frequency range 10−2 −107 Hz and the pressure range 1–5000 bar are reported. Details of the pressure generating system and of the dielectric equipment are described.
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  • 78
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 1031-1040 
    ISSN: 1435-1536
    Schlagwort(e): Monte Carlo method ; oriented branched chain ; order parameter ; molecular shape
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The conformational behaviour of phosphonic acid dialkyl ester (PAE) molecules in a uniaxial hydrophobic environment was studied using the Monte Carlo method with the well-known Metropolis algorithm. The influence of the surrounding molecules on ordering processes of the intrinsic PAE molecules was taken into account by a molecular field. The intramolecular energy was calculated using 6–12 atom-atom and torsion potential functions. Conformations were analysed using torsion angle distributions, segment and bond order parameters. The order parameters of the C-H bonds are compared with experimental results of2H NMR. Further a general method of determining the effective shape of a molecule is presented. The shape is defined by probability distribution for finding atomic coordinates within volume elements during a Monte Carlo run. Thus the asymmetry of a molecule can be visualized. PAE molecules studied show a positive asymmetry in all cases.
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  • 79
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 388-391 
    ISSN: 1435-1536
    Schlagwort(e): Dilatometer ; inhomogeneous deformation ; gas adsorption ; elastomers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Measurements in a gas dilatometer on carbon-black filled rubber cross-linked with sulfur show a large pressure drop in the specimen chamber, which to a large extent cannot be explained by a volume change of the specimen. The extension ratio at which the pressure starts to fall depends on the carbon-black content. Comparative measurements in a deformation calorimeter show that crystallisation always begins first at higher strains. It is assumed that the investigated specimens are inhomogeneously deformed even at small strains, depending on the carbon-black content, and that internal voids are formed, onto the surfaces of which gas molecules are deposited. This gas adsorption causes the pressure drop measured in the dilatometer; it is dependent on the nature of the gas. Argon shows no interaction with internal surfaces in the specimen; for measurements in an argon atmosphere, volume increases and strain-induced crystallisation can be properly determined. It is presumed that strain-induced crystallisation sets in earlier for specimens with larger carbonblack content, corresponding to the more inhomogeneous character of the deformation.
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  • 80
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 396-398 
    ISSN: 1435-1536
    Schlagwort(e): Bound water ; differential scanning calorimetry ; free water ; proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Differential scanning calorimetric studies of protein solution provided the freezable water content as a function of concentration. Total water content was obtained by vacuum dehydration. The difference between the two gave the non-freezing water content in protein solutions. The values obtained by these techniques were 2–3 times larger than those obtained on the basis of NMR measurements on the same solutions.
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  • 81
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 417-419 
    ISSN: 1435-1536
    Schlagwort(e): Osmotic pressure ; calculation ; micellar solutions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The spherical cell model of colloidal solutions is applied in calculations of the osmotic pressure of micellar systems. The predictions of the nonlinear Poisson-Boltzmann equation (MPB) and of the Modified Poisson-Boltzmann equation (MPB) containing the leading terms of the fluctuation potential and the exclusion volume corrections to the mean potential acting on simple ions are compared with the results of recent computer simulations. Both PB and MPB seem satisfactory for solutions with monovalent counterions while the MPB is preferable for studies of the solutions containing divalent countenons.
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  • 82
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 420-423 
    ISSN: 1435-1536
    Schlagwort(e): adsorption kinetics ; ionic surfactants ; electric double layer influence ; theory
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The kinetic equation to describe the adsorption process of ionic surfactants (derived in part 1) will be solved numerically. The results show the effect of parameters such as ion valencyz, thickness of theDL x −1, and surfactant parametersΓeq,K, andK ads on the adsorption process. The results can be used to decide whether the model can explain experimental data on charged surfactant molecules or not.
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  • 83
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 620-623 
    ISSN: 1435-1536
    Schlagwort(e): Biozan R ; chloramphenicol ; coupling ; antimicrobial activity ; dicyclohexylcarbodiimide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The coupling of chloramphenicol on Biozan R (Hercules) by activation with dicyclohexylcarbodiimide was studied. The esterification is influenced by the chloramphenicol/dicyclohexylcarbodiimide ratio, concentration of the reactants and reaction time. The microbial tests performed with products of different chloramphenicol contents attest their antimicrobial activity and their possible use, especially in ophtalmology.
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  • 84
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 631-637 
    ISSN: 1435-1536
    Schlagwort(e): Polysulphurnitride ; halogen doping ; multiple diffraction ; grain boundary
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract (SN)x crystals doped with iodine atoms showed ten or more additional diffuse streaks perpendicular to the b*-axis, appearing between the layer lines of the electron diffraction pattern of pristine (SN)x. However, only four of these were observed in the X ray diffraction pattern. These four diffuse streaks suggest that the iodine atoms are structured with a one-dimensional order. The extra diffuse streaks can be explained by the double diffraction between the four streaks and the spotty diffractions of (SN)x. The double diffraction results from the microfibrillar nature of the (SN)x. From X-ray microanalysis of doped (SN)x, the iodine content in the specimen was found to change mainly in the direction along the chain axis and almost constant in the direction perpendicular to it. The distribution of iodine atoms indicates that the dopants diffuse preferentially along the molecular axis through disordered domains between fine fibrils comprised in (SN)x crystals. Then the dopants are settled in the narrow disordered domains and give the extra streaked diffraction.
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  • 85
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 638-646 
    ISSN: 1435-1536
    Schlagwort(e): Impregnation ; liquid, fabric ; vacuum void
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The mechanism for liquid epoxy resin impregnation through polyester nonwoven fabric, sandwiched between two circular glass plates in atmospheric pressure, has been studied by the Kozeny-Carman equation improved by the introduction of the theoretical calculated capillary force and the gas leakage parameter for the void formation in the impregnating area. Impregnating velocity increases with reduced gas pressure. Experimental data on the vacuum impregnation were analyzed by the improved Kozeny-Carman equation by using wettability under measurements of the ascending heights due to liquid epoxy resin impregnation in a vacuum. The gas leakage quantity, obtained from the gas leakage parameter, is related to the gas pressure at the starting point of the impregnation. Voids for most of the impregnation stage disappear with passing impregnating time, 120 minutes as well as breaking the vacuum in the chamber.
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  • 86
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 673-681 
    ISSN: 1435-1536
    Schlagwort(e): Contact angle ; drop size ; vapor environment
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Advancing contact angles are reported for the water-PTFE, water-copper, water-stainless steel, water-PMMA andn-decane-PTFE systems for a range of liquid drop sizes. The angles were determined at 25 °C in an air or nitrogen-saturated atmosphere and compared with those measured at the boiling point in an environment only of its vapor. For water-PTFE and water-PMMA systems, a decrease in contact angle with decreasing drop size was observed in an air-saturated environment at 25 ° confirming the data of Good and Koo. An increase in contact angle however occurred with decreasing drop size at the boiling point in the pure vapor atmosphere confirming the results of Boyes and Ponter. The introduction of nitrogen decreased the contact angle although the trend remained the same.
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  • 87
    ISSN: 1435-1536
    Schlagwort(e): Binary monolayers ; cephalines ; surface and equilibrium spreading pressure ; demixing ; thermodynamics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Beschreibung / Inhaltsverzeichnis: Abstract 1. The F/A-isotherms of the binary system dimyristoylcephaline/dipalmitoyl-N-methyl-cephaline using premixed and separate spreading at 295 K and the concentration dependence of the equilibrium spreading pressureF e in the temperature range between 295 K and 308 K were measured and compared. 2. The thermodynamical analysis of the F/A-isotherms and of the equilibrium spreading pressure refers to the conclusion that in the binary monolayers under the equilibrium conditions both cephalines arefully immiscible. 3. It was shown that various spreading techniques lead to different experimental results. From the long-term investigations we found that the equilibrium state of the mixtures was reached immediately in the case of separate spreading. On the other hand with pre-mixed spreading this equilibrium state was obtained only after 20 h. 4. The shape of the F/A-isotherms of dimyristoyl-cephaline depends on the surface technique. From the flat parts in the F/A-isotherms of dimyristoyl-cephaline, obtained by discontinuous compression, and from the flat parts in theF e- xb-curves of the mixtures it was shown that in the monolayers a phase transition offirst order takes place.
    Notizen: Zusammenfassung 1. Es wurden die Konzentrationsabhängigkeit der F/A-Isothermen (Gemischt- und Getrenntspreitung) beiT=295 K und die SpreitungsdrückeF e des binären Systems Dimyristoylkephalin/Dipalmitoyl-N-methylkephalin im Temperaturbereich zwischen 295 K bis 318 K durch Anwendung verschiedener Oberflächentechniken gemessen. 2. Die thermodynamische Analyse der Konzentrationsabhängigkeit der F/A-Isothermen und der Spreitungsdrücke ergab, daß beide Kephaline unter Gleichgewichtsbedingungen vollständig unmischbar sind. 3. Aus Langzeituntersuchungen geht hervor, daß sich der Gleichgewichtszustand der Mischung bei der Getrenntspreitung sofort, dagegen bei der Gemischtspreitung erst nach ∼ 20 Stunden einstellt. 4. Der Verlauf der F/A-Isotherme des Dimyristoylkephalins hängt sowohl von der Kompressionstechnik als auch von der -geschwindigkeit ab. Im Fall der diskontinuierlichen Kompression wird der Gleichgewichtszustand erreicht. Unter diesen Bedingungen enthält die Isotherme eine Unstetigkeit in der Fläche (horizontaler Bereich). Es handelt sich um eine Umwandlung 1. Ordnung. Diese Umwandlung 1. Ordnung ist auch für die Mischungen im Temperaturbereich zwischenT=295 K bisT= 303 K typisch. In denF e- xb-Kurven treten ebenfalls horizontale Bereiche auf.
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  • 88
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    Colloid & polymer science 263 (1985), S. 682-685 
    ISSN: 1435-1536
    Schlagwort(e): 5-trifluorouracial ; sodium poly-α ; L-glutamate ; interaction ; viscosity ; 5-trifluoromethyluracil
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The purpose of our research is to obtain an understanding of the binding mechanism and its correlations in terms of chemical structure and the potentiactive drug activity. The interaction of 5-fluorouracil (5-fluorouracil is used as an anticancer drug) with sodium poly-α,L-glutamate in aqueous solution was studied with a spectral method and viscosity measurement. From the binding data, the molar change in enthalpy, entropy and the number of binding sites on the polymer were calculated. It is very interesting that the value ofΔH0 of the binding of 5-fluorouracil with sodium poly-α,L-glutamate is smaller than that of 5-trifluoromethyluracil (although 5-trifluoromethyluracil is not used as an anticancer drug, the compound has a similar structure to 5-fluorouracil).
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  • 89
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 686-689 
    ISSN: 1435-1536
    Schlagwort(e): Soybean-phosphatidylcholine ; X-ray ; dielectric constant ; phase-transition ; chain-melting
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Soybean-Phosphatidylcholine Phospholipon® 100 has a stable gel conformation in the as-prepared state. We observed a main phase transition (chain melting) above 30 °C in the first heating run. This transition is marked 1. by a change of the lamellar repeat distance recorded by small angle X-ray diffraction, and 2. by an increase of the imaginary part of the dielectric constant. After the first heating up to + 90 °C the chains “melt” in a broad temperature range between −60 °C and +90 °C. The high stability of chain conformation in the temperature range −60 °C to +30 °C of the as-prepared state is due to the low water content of the material.
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  • 90
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 697-707 
    ISSN: 1435-1536
    Schlagwort(e): Semicrystalline polymers ; hardness ; modulus ; non-homogeneous microphase ; structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract An analysis of micro-hardness and elastic modulus data for different lamellar systems in the light of both eutectoid copolymer and chain folded lamellar microphases is presented. A novel thermodynamically derived expression offering a fair description of hardness (stress required to plastically deform a crystal) of autonomous non-homogeneous microphases in terms of the average crystal thickness, including a defective surface boundary is developed. The present results characterize the mechansim of plastic deformation as primarily governed by the initial mosaic-block structure controlling the “solid state” mechanism underlined. The average dimensions of the remaining blocks after crystal destruction are thus related to the original block dimensions before plastic deformation. Within this context it is shown that the dissipated energy for crystal destruction increases very rapidly with the molar mass-function of crystalline material. The elastic deformation of these lamellar systems at small strains is correlated to the rubber-like behaviour of the cluster-network. Finally, the role of the average thickness of the non-homogeneous microcrystallites is stressed as describing concurrently the elastic and plastics properties of the polymer allowing a quantitative description of the correlation found between micro-hardness and elastic modulus.
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  • 91
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 708-713 
    ISSN: 1435-1536
    Schlagwort(e): PMMA ; association ; photoelasticity ; optical anisotropy ; crosslinking density
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Swollen PMMA networks show significant deviations from the theory of rubber elasticity. The unusual mechanical, optical and swelling properties have been explained by the existence of associations, well known for PMMA solutions. Unswollen PMMA networks show stress optical properties which are very similar to the networks swollen in carbon tetrachloride which is known as a strong complexing solvent. This indicates that associations exist in the bulk material. Swelling in carbon tetrachloride does not change the content of associations, only the glass transition temperature is reduced. Increasing the amount of crosslinking agent proves that the stress optical coefficient depends on the crosslinking density. This is contrary to the theoretical predictions. An explanation given by the effect of short network chains is not satisfactory. However, the consideration of a crosslinking chain instead of a crosslinking point gives a sufficient explanation. An oriented crosslinking chain gives a positive contribution to the total optical anisotropy while a PMMA chain shows a change from negative values (hindered rotation) to positive values (free rotation).
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  • 92
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 738-743 
    ISSN: 1435-1536
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The creep of a rigid material based on poly(vinylchloride) modified with benzidine is studied under tensile stress conditions. Based on the proposed rheological model, the creep equation is derived. The modifications induced by the mechanical stress on some physical properties of the material are studied. The analysis of the facture surfaces shows a “brittle” character of the fracture, especially in the final stage of the process.
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  • 93
    Digitale Medien
    Digitale Medien
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    Colloid & polymer science 263 (1985), S. 744-748 
    ISSN: 1435-1536
    Schlagwort(e): Carrageenan ; gel ; alkali metal ion ; DSC ; large deformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Differential scanning calorimetry and extension tests were carried out on kappa-carrageenan gels in the presence of the alkali metal salts LiCl, NaCl, KCl and CsCl. The endothermic peak accompanying the melting of gels shifted to higher temperatures with increasing concentrations of alkali metal salt. The breaking force of gels increased with increasing concentrations of added KCl and CsCl, and decreased with increasing concentrations of added NaCl. The breaking force of the gel containing LiCl decreased with the first level of addition, then increased slightly with two further additions and finally decreased again at the highest level of addition.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 25-29 
    ISSN: 1435-1536
    Schlagwort(e): Mechanochemical reactions ; molecular mechanism of fracture ; PVC ; tensile stress ; deformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract This paper is concerned with molecular phenomena appearing during deformation of poly(vinyl chloride) under tensile stress conditions. By using indirect techniques (reactions with radical acceptors, with vinylic monomers, electron microscopy) the formation of free radicals, appearing as a consequence of splitting of chemical bonds, is evidenced. The amount of reacted radical acceptor or monomer was proved to be related to solution concentration and to the duration of mechanical stress.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 3-24 
    ISSN: 1435-1536
    Schlagwort(e): Zetapotential ; electrokinetic potential ; fibers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract A survey is given on both theoretical background and methodical details of zeta-potential measurements on fibers. Electro-osmosis and streaming potential/streaming current measurements can be used in order to obtain correct zeta-potentials. Both measuring principles yield the same values for zeta-potential if the errors due to resistance measurements are avoided. This agreement as well as the independence of zeta-potential of applied voltage (in the case of electro-osmosis) and hydrostatic pressure (in the case of streaming potential/streaming current) point out that the Stern-potential at the boundary immobile/diffuse layer can be determined. Electrophoresis and measurement of other electrokinetic phenomena give values related to but not identical with the zeta-potential. Applications of electrokinetic measurements for investigating fiber problems in production, processing and finishing are reviewed. Parameters determining the zeta-potential of fibers are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 42-50 
    ISSN: 1435-1536
    Schlagwort(e): Chemical potential ; uniform membrane ; concentration dependent sorption ; concentration dependent diffusivity ; sorption transient ; permeation transient
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract In a linear dependence of the sorption coefficient S on the equivalent pressure of the penetrant the differences between the Fickian and chemical potential formulation of the diffusion current are very soon larger than 20%, the assumed and tolerated error limit of the experiment. It turns out that the zero concentration diffusion coefficientD o determined from the sorption or permeation transient on the basis of the chemical potential basis is larger than that determined on the basis of Fick's law. The exponential concentration dependence as measured byγ, however, is very little affected up toγc o=4. The steady state current of the permeation mulitplied by the time-lag yields the concentration dependent sorption practically independent of the formulation used.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 51-57 
    ISSN: 1435-1536
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Theoretical equations for the permittivity and conductivity of a heterogeneous mixture containing an oriented dispersed phase of spheroidal shape are limited to low volume fractions of dispersed phase. Two new sets of equations have been derived here for such systems using approaches which have been shown previously to be applicable to higher concentrations. One set has generalised forms of equations given by Bruggeman and Hanai and includes simplifications applicable to oil in water (O/W) and water in oil (W/O) systems. The other set has generalised forms of an equation given by Looyenga. Tabulated mixture permittivityε and dielectric incrementΔε values are presented and, with the exception ofO 〈W systems containing prolate spheroids, the two types of equation show significant differences in bothε andΔε. For both typesΔε is strongly dependent on the ratio of the conductivities of the two media of aW/O system. The relevance of the mixture equations to the electrical behaviour of micellar, microemulsion and liquid crystalline systems is considered.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 941-947 
    ISSN: 1435-1536
    Schlagwort(e): Electrophoretic mobility ; calcium oxalate monohydrate ; liquid mixture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract An experimental investigation on electrophoresis of calcium oxalate monohydrate in several liquid mixtures (methanol-, ethanol-, 2-propanol-, and methanol-acetonewater) is described. The electrophoretic transport is considered from the view-point of the Thermodynamics of Irreversible Processes. Linear relations have always been found between the mass flux and the applied electric field. The ζ-potential of the interface C.O.M./liquid mixture has been estimated by using the classial theory of electrophoretic mobility of colloidal particles. The influence of the composition of the mixture on the electrophoretic coefficient has been discussed on the basis of the variation of ζ-potential, viscosity and dielectric constant with the molar fraction of alcohol for binary mixtures and acetone for ternary mixtures. The concentration dependence of the electrophoretic coefficient is found to be linear only in the latter case.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 965-972 
    ISSN: 1435-1536
    Schlagwort(e): Solid-state polymerization ; butadiene derivatives ; amphiphilic butadienes ; monolayers ; Langmuir-Blodgett multilayers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract The polymerization of long chain derivatives of sorbic and muconic acid was studied in the solid state. Crystals of sorbic acid n-octadecylester (1), sorbic acid n-octadecylamide (2), and 6-n-octadecanoylamino sorbic acid (3) were found to rapidly polymerize upon UV- orγ-irradiation. A 1,4-trans-polymer was obtained in a high yield. Crystals of muconic acid di-n-octadecylester (4) and muconic acid di-n-octadecylamide (5) were completely photoinactive. Polymerization of3 was also investigated in monomolecular layers at the air-water interface and in Langmuir-blodgett type multilayers. The polymer formed upon UV- irradiation of mono- and multilayers was identified by infrared spectroscopy as the 1,4-trans-adduct.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Springer
    Colloid & polymer science 263 (1985), S. 985-990 
    ISSN: 1435-1536
    Schlagwort(e): Isotactic polypropylene ; small molecular additives ; thermal treatment ; phase transition ; wide-angle X-ray diffraction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Maschinenbau
    Notizen: Abstract Investigations into the transformation of hexagonal into monoclinic modification in isotactic polypropylene (iPP) were carried out. The hexagonal phase (β) was obtained by crystallization from a melt of iPP samples containing small molecular compounds (additives). A decline in the amount ofβ-modification and changes of dimensions of ordering areas, perpendicular to the chain axes of iPP, was analysed at various temperatures and times of heating. The interdependence between the structure of additives and the amount ofβ-phase occurring and also the stability of this modification during thermal treatment was observed. Obtained results indicated that only some additives play the role of moderating agents for theβ →α phase transition process.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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