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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 121 (1988), S. 961-970 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis of [2]-Catenanes from [2]-RotaxanesStarting from the rotaxane 18a a mixture of catenane 21 and rotaxane 23 is obtained by attaching a polymethylene bridge between the methylene groups in α-position of the sulfonyl groups. The isocyclic catenane 28 containing a 28- and a 46-membered ring is obtained from the catenane 21 by splitting the bonds between the bridgehead atoms and the sulfonyl groups. The 1H-, 13C-NMR, and mass spectra of this compounds are discussed.
    Notes: Ausgehend von dem Rotaxan 18a wird durch Angliederung einer Polymethylenbrücke zwischen den beiden zu den Sulfonylgruppen α-ständigen Methylengruppen ein Gemisch von Catenan 21 und Rotaxan 23 synthetisiert. Aus 21 wird nach Spaltung der Bindungen zwischen den Brückenkopfatomen und den Sulfonylgruppen das isocyclische Catenan 28, bestehend aus einem 28-und einem 46-gliedrigen Ring, erhalten. Die 1H-, 13C-NMR-Spektren und Massenspektren dieser Verbindung werden diskutiert.
    Additional Material: 1 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 1374-1399 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Directed Synthesis of Translationally Isomeric [3]-Catenanes1)In a multi-step reaction sequence the tetrahydroxymetacyclophane 12c is synthesized. Acetalisation with 1,25-dichloro-13-pentacosanone followed by nitration and reduction afforded the diamine 13c. By cyclization of this compound in 2-pentanol with sodium carbonate and sodium iodide under high dilution conditions the monomeric products 16, 17, and 18 are obtained in yields of 21.4, 7.7, and 0.9%, respectively. On the basis of mass, 13C NMR and 1H NMR spectra the structure of these compounds is discussed. Starting from the precatenane 16 the [3]-catenanes 25a, b,c and 26a, b, c are obtained in a multi-step reaction sequence. The structure of these compounds is confirmed by mass, 13C NMR, and 1H NMR spectroscopic investigations.
    Notes: In einer vielstufigen Synthese wird das Tetrahydroxymetacyclophan 12c synthetisiert. Durch Acetalisierung mit 1,25-Dichlor-13-Pentacosanon, nachfolgender Nitrierung und Reduktion wird das Diamin 13c erhalten. Dessen Cyclisierung in 2-Pentanol in Gegenwart von Natriumcarbonat und Natriumiodid unter Verdünnungsbedingungen ergibt die monomeren Cyclisierungsprodukte 16, 17 und 18 in Ausbeuten von 21.4. 7.7 und 0.9%. Die Struktur dieser Verbindungen wird anhand der Massen-, 13C- und 1H-NMR-Spektren diskutiert. In einer mehrstufigen Reaktionsfolge werden aus dem Prä-[3]-catenan 16 die [3]-Catenane 25a, b, c und 26a, b, c erhalten. Die Struktur dieser Verbindungen wird durch 13C-NMR, 1H-NMR- und massenspektroskopische Untersuchungen bewiesen.
    Additional Material: 1 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 399-410 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photoinduced Electron Transfer between Arenediazonium Cations and AnionsAnions X⊖ can act as donors in electron transfer reactions to photoexcited arenediazonium ions. The yield of the arene formed in this reaction increases with decreasing electrochemical oxidation potential EoxD of X⊖ (X⊖ = BPh4⊖, Br⊖, HOOC—COO⊖, Cl⊖, BF4⊖). The oxidized donor X· (Cl·, ·COO⊖) and aryl radicals Ar· benig intermediates of the reductive dediazoniation of ArN2⊖ can be detected by spin trapping with nitrosodurene (ND) and phenyl-tert-butylnitrone (PBN). A solvent effect in the electron transfer reaction is interpreted in terms of ion pairing, where the electron transfer is favored by preorientation and a short distance between the electron donor and the acceptor previous to excitation of ArN2⊖ by light.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 33 (1987), S. 319-321 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 262-271 
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pressure pulsations in hydraulic systems, generated by reciprocating pumps, can cause serious problems with regard to plant safety and reliability. In particular, fatigue problems arise in high-pressure piping systems. The available knowledge is not sufficient for an accurate computation of pressure peaks in the piping of reciprocating pumps. A number of calculation models are available which, however, neglect both fluid compressibility and friction. This contribution presents a calculation method which allows a precise modelling of various pump installations. Comparison of calculated and experimental data shows a good agreement and provides a validation of the computational model.
    Additional Material: 18 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1113-1120 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A nonlinear finite element model for the static analysis of football helmets is developed as a first step in a methodology for the mathematical modeling of helmets. Polycarbonate and acrylonitrile-butadiene-styrene are considered as the shell material for the helmet. Such a methodology can be used to predict helmet response to loading and impact and can be incorporated in a computer program studying injuries caused by helmeted head collisions in football. Numerical results in terms of force-deflection curves, maximum stresses, and work of deformation are given. The influence of the polymeric material forming the helmet shell on energy absorption is studied. The effect of the internal padding material and suspension system is also considered.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Flow control for small metering pumps with continuous and pulsating flow. Metering of small flows with high discharge pressure is performed mainly by displacement metering pumps. The necessary mass-flow control shows problems with pulsating piston- or diaphragm metering pumps. A survey explains the presently available continuous and discountinuous methods of mass- and volume flow control. Special investigations have been performed with differential scales and mass flow meters based on the Coriolis- and the thermal principle. The differential weighing method shows good accuracy down to minimum mass flows of 0.1 kg/h. This method is expensive and requires vibration protected installation. The Coriolis flow meter, applicable over a similar range, precisely integrates the pulsating signal, but requires damping or signal averaging for regulation purposes. Thermal flow meters prove rather sensitive to temperature fluctuations. Under stable conditions and with proper calibration this principle may be applied to flows even below 0.1 kg/h.
    Additional Material: 26 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 57 (1985), S. 395-409 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Dosage of solids and liquids. Dosage of reaction components is an important step in chemical engineering processes. In an age of increasing automation, the development of dosage procedures is highly topical; electronics and data processing have long made inroads into dosage procedures. However, today's more stringent demands with regard to pressure, temperature, viscosity, and abrasion necessitate intensified research and development efforts. The present article considers mainly volumetric and geometric dosage methods. The many types of metering pumps cover a large area of dosage of liquids. Minimal flow rates, pressures up to several 1000 bar, and also dangerous and difficult fluids can all be safely handled. Leakproof designs with membranes, tubes, or bellows as displacement devices are particularly important nowadays. Volumetric dosage of solids requires establishment of a reproducible packing density. The survey considers the principle methods of dosage (also against pressure) with special emphasis on screw dosage. Gravimetric dosage methods are extremely reliable and accurate but generally require volumetric systems for energy supply. Especially when used in combination with metering pumps or screw dosage, differential balances have numerous possible applications.
    Additional Material: 25 Ill.
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  • 9
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Wear of automatic pump valves by abrasive suspensions. In pumping of abrasive suspensions with reciprocating displacement pumps against high pressures, the pump valves prove to be subject to serious wear. Wear of the piston seal can usually be avoided by washing or by separating membranes. Pump valves are fitted with elastic or rigid seals. To resist corrosion and temperature effects, frequently the only possible approach is to finish them in metallic or carbide materials. The major kinds of wear are demonstrated by a tribological study. The rates of wear found for a real valve model with a high pressure experimental setup depend upon the pressure and frequency of reciprocation. A hardness-dependent region of instability exists where wear scoring arises. The volume wear rate for various arrangements of materials and abrasive particles exhibits a crest/trough nature. A design strategy and construction aspects are considered and compared with practical experience.
    Additional Material: 22 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 61 (1989), S. 136-140 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Accuracy of dosage. Confusion sometimes surrounds the concept of dosage accuracy. For this reason, standard definitions and testing and calculation procedures are proposed for dosage accuracy, dosage error, and dosage constancy. Representation of the relationship between dosage error and dosage constancy within the area of tolerance of the dosage accuracy is new. Since the measurement of all error quantities is always bound to relate terms such as short-term, long-term, and momentary dosage error to a stated time base. This also facilitates a conceptually smooth transition to operating dosage errors observed in long-term operation. It would be convenient if some standardization of the concepts, and possibly a set of rules, could be developed on this basis. Evaluation of measured results on comparing guarantees would then be conducted in relation to the accuracy of measurement.
    Additional Material: 13 Ill.
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