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  • Wiley-Blackwell  (200)
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  • 1
    Electronic Resource
    Electronic Resource
    numerical investigation of free convection between two vertical coaxial cylinders (1970)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 16 (1970), S. 1005-1010 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Free convection between two vertical coaxial cylinders was studied by solving the governing transport equations as an initial-value problem. The coupled, nonlinear, partial differential equations were converted into a set of difference equations by use of an alternating-direction implicit finite-difference numerical scheme. Twenty-four different combinations of Prandtl and Grashof numbers, and height to annular spacing ratios were used to characterize the problem. The results are presented primarily in the form of contour maps for the steady-state isotherms and streamlines.For Rayleigh numbers greater than 5 × 103, a fully developed boundary-layer flow was found to exist in the cavity. The interior region of the annulus was found to be thermally stratified and to possess a nearly uniform vertical temperature gradient, with a unicellular flow pattern being generated.With Rayleigh numbers of 5 × 104 and greater, it was found that the flow patterns could not be properly described with a grid spacing of 1/10. The variation of the steady-state mean Nusselt number with Prandtl and Rayleigh numbers and with geometric ratios was also investigated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690160624
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  • 2
    Electronic Resource
    Electronic Resource
    New mechanisms for the biosynthesis and metabolism of 2-keto-L-gulonic acid in bacteria (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 17 (1975), S. 1485-1514 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: L-Sorbose is oxidized to 2-keto-L-gulonic acid (KGA) via the following sequence of reactions which we call the “sorbosone pathway”: L-sorbose ⇌ L-sorbosone → KGA. The first step is reversible and is mediated by enzymes found in a soluble fraction obtained from Pseudomonas putida ATCC 21812. Although no cofactor requirements were found for the forward reaction, the reverse reaction clearly required NADH. Enzymes for this NADH-dependent synthesis of L-sorbose could be differentiated on the basis of molecular weights. The second step in the sorbosone pathway is catalyzed by a particulate enzyme found in extracts from P. putida and Gluconobacter melanogenus IFO 3293. The rate limiting reaction in the sorbosone pathway is the synthesis of L-sorbosone. In addition to P. putida, Klebsiella pneumoniae (ATCC 27858) and Serratia marcescens (ATCC 27857) also contain the enzymes which catalyze the reactions of the sorbosone pathway. Two of the bacteria studied, P. putida and G. melanogenus, also contain an enzyme involved in the further metabolism of KGA to L-idonic acid. This enzyme, referred to as KGA-reductase, is found in the soluble fraction of cell-free extracts and is dependent on NADH or NADPH.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260171009
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  • 3
    Electronic Resource
    Electronic Resource
    Oxidationssäurenkorrosion durch DachdeckungsbitumenAuszug aus der Graduierungsarbeit von St. Tenbrock, Institut für Werkstoffkunde der FH-Düsseldorf. (1980)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 31 (1980), S. 21-27 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Corrosion by acids formed by oxidation of bitumineous roof coveringsIn recent years there has been an increased number of case histories involving metallic roof draining systems in connection with bitumineous materials. An evaluation of 64 histories has shown that 60% of the cases could be attributed to unprotected bitumineous coatings, mastix and undefined special paint coats, 24% to weld-seems without slate covering and about 16% to inadequately sanded roof areas. No damages were counted in the case of roofs with adequate gravel or slate covering. Short-time weathering in the laboratory has confirmed these findings. It could be shown that bitumineous materials are oxidized during weathering and formed carbonic acid. It has further been shown that reaction products of chemicals used for blowing or improving bitumineous materials are not the cause of such damages. The oxidation and thus the formations of acids can be used by adequate sanding of the bitumineous materials so that the damage to roof draining systems can be excluded.
    Notes: In den letzten Jahren kam es vermehrt zu Schäden an Dachentwässerungssystemen aus metallischen Werkstoffen in Verbindung mit bituminösen Baustoffen.Eine Untersuchung von 64 Schadensfällen ergab, daß 60% der Schäden auf ungeschützte bituminöse Anstriche, Spachtelmassen und nicht definierte Spezialanstriche, 24% auf ungeschützte, d. h. nicht beschieferte Schweißbahnen und etwa 16% auf Dachflächen mit lückenhafter Bestreuung entfallen. Dagegen traten bei ordungsgemäß bekiesten oder beschieferten Dachflächen keine Schäden auf. Im Labor durchgeführte Kurzzeitbewitterungsprüfungen bestätigten diese Untersuchung. Es zeigte sich, daß Bitumen unter Einwirkung von Witterungseinflüssen oxidiert und dabei Carbonsäuren entstehen. Es konnte weiterhin geklärt werden, daß Reaktionsprodukte von Chemikalien, die beim Blasen oder zur Vergütung von Bitumen eingesetzt werden, als Verursacher ausscheiden.Nur eine ordungsgemäße Bestreuung schwächt die Oxidation und damit die Säurebildung, so daß eine Gefährdung metallischer Dachentwässerungssysteme ausgeschlossen werden kann.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19800310104
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  • 4
    Electronic Resource
    Electronic Resource
    Dynamics of distillation with high product puritiesExtended version of a paper presented by Dr. G. Wozny at the internal group meeting of the GVC Technical Committee on “Mass Transfer Processes” and “High-Pressure Process Engineering”, April 10 to 11, 1986. (1987)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 338-348 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For the simulation of steady- and non-steady-state behaiour of separation columns, a simulation program was developed and employed for the calculation and optimization of methanol-water separation. The demand for increasingly higher purities and energy-saving optimization of plants results in complex column configurations and thus in complex control schemes. The number of possible control schemes was reduced on the basis of heuristic rules. By simulating the process, the optimum control and manipulative variables and measuring points were determined from the reduced number of control concepts. A control scheme was introduced. The model was verified by simulation of the dynamic behaviour of the process. The investigation included the effects of computing technique, time interval, model reduction and tray hold-up on the results. Thus, various effects and interactions were verified theoretically with respect to the robustness of the model. This was followed by a simulation of the non-ontrolled and controlled column. By implementing the controllers in the existing column program, the computer can predict the control parameters. These parameters were checked and corrected when the metahnol-ater column was put in operation. In the start-up phase, major problems were caused by the sensitivity and failure rate of density, throughput and pump measuring sensors. Feed impurities were another source of problems. Operation with high product purities is possible, with a side stream to discharge impurities.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270100141
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  • 5
    Electronic Resource
    Electronic Resource
    POYCARBONAT UND LICHT-Einsatz von Polycarbonat in optisch relevanten Gebieten -Herrn Prof. Dr. D. Braun zum 60. Geburtstag gewidmetVortrag anläßlich der Tagung der Fachgruppe “Makromolekulare Chemie” der Gesellschaft Deutscher Chemiker über “Polymere und Licht”, in Bad Nauheim vom 7. bis 9. Mai 1990. (1990)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 183 (1990), S. 243-272 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polycarbonate (PC) based on 4,4'-dihydroxydiphenyl-2,2-propane has adchieved an outstanding market relevance due to its extraordinary physical and technical properties, especially due to the combination of excellent impact strength and high heat distortion temperature (HDT) combined with good optical and electrical properties.This very attractive balance of properties has led to a broad and still expanding use of PC in different optical application areas. Therefore it has reached a significant importance as a material for glasing (compact sheet and twin wall sheet) and also for optical lenses. For lenses the high refraction index of PC (n = 1,58) and its low density have shown as additional advantages. Recently PC was introduced as a base material for polymeric optical fibers (POF) in the market: Despite its inherently high optical loss (about 800 dB/km at λ = 820 nm) PC has proved as an attractive material because of its high refractive index (cheap cladding, narrow bending radii) and its good HDT (use at relatively high temperatures, e.g. near the engine of automobiles), so far the maximum fiber length will not exceed 30 m.During the last decade PC with extremely high flow and purity became the material of choice for music consumer industry (compact disk: CD) and for optical data storage technology. So far all the CDs were produced worldwide from PC (1988: 450 Mio CD, 1989 about 650 Mio CD). These special PC grades are used for WORM disks (write once read multiple) and EOD disks (erasable optical disks) with diameter up to 13 cm. These disks are still in the phase of market introduction. For disk diameters greater than 13 cm up to 30 cm experimental products with very low birefringence combined with increased stiffness are currently under development (e.g. blends of modified PC with modified SAN).The continuous improvement of the commercial PC grades and the new development of structurely modified PC and special blends based on PC will lead to a further increasing consumption of PC and to further expanding applications of PC especially in the optical market area.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1990.051830113
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  • 6
    Electronic Resource
    Electronic Resource
    Synthetische Arbeiten in der Reihe der aromatischen Erythrina-Alkaloide, XIV. Übertragung der Glyoxylester-Synthese auf Dihydroresorcin (1970)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 103 (1970), S. 1522-1535 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Syntheses of Aromatic Erythrina-Alkaloids, XIV. Application of the Glyoxylester Synthesis to DihydroresorcinolThe monocycloketal 7 of dihydroresorcinol yields, via glyoxylester synthesis, the condensation product 10. On treatment with dilute phosphoric acid, 10 hydrolyses to give the partially hydrogenated ketoisatin derivative 14a which is stabilised by conjugation and cannot be cyclised. In the presence of crystalline phosphoric acid 10 forms a violet cation, Pictet-Spengler cyclisation of which leads to a mixture of stereoisomeric spiroisoquinolines (22). From the mixture two racemates are isolated, the n. m. r. analysis of which permits the assignment of cis- and trans-configurations according to the formulae 22A and 22B.
    Notes: Aus dem Monocycloketal 7 des Dihydroresorcins wird auf dem Weg der Glyoxylestersynthese die Cyclisierungsvorstufe 10 gewonnen. Sie hydrolysiert unter der Einwirkung von verdünnter phosphorsäure zu dem Partiell hydrierten Ketoisatin-Derivat 14a, das durch Konjugation stabilisiert und nicht cyclisierbar ist. Mit kristalliner Phosphorsäure entsteht aus 10 ein violettes Kation, das durch Ringschluß nach Pictet-Spengler zu einem Gemisch stereoisomerer Spiroisochinoline 22 abreagiert. Nach Auftrennung in zwei Racemate wird durch NMR-Analyse die sterische Zuordnung zur cis- und trans-Reihe entsprechend den Formulierungen 22A und 22B ermittelt.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19701030523
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  • 7
    Electronic Resource
    Electronic Resource
    Bullvaleno-kronenether - Kronenether mit variablen Ringgrößen (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3800-3812 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Bullvaleno-Crown Ethers with Variable Ring SizesSyntheses and properties of the bullvaleno-crown ethers 1a-e are described. An analysis of the temperature dependent 1H NMR spectra proves an easily occurring thermally induced change of ring size within certain limits. The relatively small association constants reveal a weak „guesthost„ interaction of 1a-e with alkali and ammonium rhodanide. The stoichiometry of the complexes and preferred positional isomers of the ligands of the complexes are reported for alkali and ammonium picrates. The possible adaption of the „breathing„ crown ethers to cations of different sizes is not observed.
    Notes: Es werden Synthesen und Eigenschaften der Bullvaleno-kronenether 1a-e beschrieben. Die Analyse der temperaturabhängigen 1H-NMR-Spektren beweist, daß sich die Ringgröße dieser Verbindungen thermisch leicht innerhalb bestimmter Grenzen verändert. Die relativ kleinen Assoziationskonstanten zeigen nur eine schwache „Gast-Wirt“-Wechselwirkung zwischen 1a-e und Alkali- und Ammoniumpikraten sowie tert-Butylammoniumrhodanid an. Die Stöchiometrie der Komplexe und bevorzugte Positionsisomere der Liganden in den Komplexen werden für Alkali- und Ammoniumpikrate angegeben. Die mögliche Adaption der „atmenden“ Kronenether an Kationen verschiedener Größe wird nicht beobachtet.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831161205
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  • 8
    Electronic Resource
    Electronic Resource
    Sechs- und achtgliedrige Schwefel-Stickstoff-Heterocyclen - Verbindungen des Schwefels mit den formalen Oxidationsstufen 2, 4 und 6 (1979)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 112 (1979), S. 1372-1379 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Six- and Eight-membered Sulfur-Nitrogen-Heterocycles - Compounds of Sulfur with the Formal Oxidation States 2, 4, and 6The reaction of the eight-membered compound S4N4O2 with silylamines having several substituents and tris(trimethylstannyl)amine yields the six- and eight-membered heterocycles 1-3. The six-membered rings 1 and, 2 are the first examples where the sulfur atoms have the formal oxidation states 2, 4, and 6. 1 and 2 can also be synthesized by the reaction of silyl- and stannyl-substituted sulfur diimide with N-sulfinylfluorosulfonamide. 2 and 3 are also obtained by the reaction of S4N4O2, with trimethyltin azide. The structure of 2 was determined by an X-ray analysis. 2 crystallizes in the space group P2l. Five of the six-ring atoms form a plane. The nitrogen atom coordinated to the tin lies 78 pm above this plane. The S — N bond lengths are discussed in connection with known structures.
    Notes: Die Umsetzung der Achtringverbindung S4N4O2 mit mehrfach substituierten Silylaminen und Tris(trimethylstannyl)amin führt zu den Sechs- bzw. Achtring-Heterocyclen 1-3. Die Sechsringe 1 und 2 sind die ersten Beispiele, in denen der Schwefel die formalen Oxidationsstufen 2, 4 und 6 erreicht. 1 und 2 lassen sich auch durch Umsetzung von N-Sulfinylfluorsulfonamid mit silyl- oder stannylsubstituiertem Schwefeldiimid darstellen. 2 und 3 sind ebenfalls zugänglich durch die Umsetzung von S4N4O2 mit Trimethylzinnazid. Die Struktur von 2 wurde durch eine Röntgen-analyse aufgeklärt. 2 kristallisiert in der Raumgruppe P21. Fünf der sechs Ringatome bilden eine Ebene, während das Stickstoffatom, welches am Zinnatom gebunden ist. um 78 pm außerhalb der Ringebene liegt. Die S — N-Bindungslängen werden im Zusammenhang mit bisher bekannten Strukturen diskutiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19791120431
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  • 9
    Electronic Resource
    Electronic Resource
    Salze des S4N4O2 - Beispiele für die Abhängigkeit de Struktur von cyclischen Schwefel-Stickstoff-Verbindungen von der Elektronendichte (1981)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 201-208 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Salts of S4N4O2 - Examples for the Dependence of the Structure of Cyclic Sulfur-Nitrogen Compounds on the Electron DensityThe reaction of S4N4O2 with nucleophiles (alcoholates, alcohols, azides, and isocyanates) in alcoholic solution leads to the salts 1a-h. The Structure of 1h was determined by means of an X-ray analysis. 1h crystallizes in the space group P21/n and contains a transannular S—S-bond with 248.2 (2) pm. The structure of 1h is considered in connection with the increase of electron density and compared with the results of the X-ray analysis of CH3Si(NSN)3SiCH3 (2). 2 is cubic (space group P4132). The bicyclic molecule (S—N 150.4(2), Si—N 173.7 (2) pm) has approximate D3h symmetry and shows no S—S bonds across the rings.
    Notes: Die Umsetzung von S4N4O2 mit Nucleophilen (Alkoholate, Alkohole, Azide und Isocyanate) in alkoholischem Medium führt zu den Salzen 1a-h. Für 1h wurde eine Röntgenstrukturanalyse durchgeführt. 1h kristallisiert in der Raumgruppe P21/n und enthält eine transannulare S—S Bindung mit 248.2 (2) pm. Die Struktur von 1h wird im Zusammenhang mit der Zunahme der Elektronendichte betrachtet und mit den Ergebnissen der Röntgenstrukturanalyse von CH3Si(NSN)3SiCH3 (2) verglichen. 2 kristallisiert kubisch (Raumgruppe P4132). Das bicyclische Molekül (S—N 150.4 (2), Si—N 173.7 (2)pm) hat praktisch D3h Symmetrie und zeigt keine S—S-Bindungen im Ring.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19811140120
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  • 10
    Electronic Resource
    Electronic Resource
    Zur Frage der Stellungsisomerie bei disubstituierten Bullvalenen (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 2339-2349 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Concerning the Question of Positional Isomerism in Disubstituted BullvalenesWe report about 15 new disubstituted bullvalenes (2, 4, 5, 11, 12, 14-20, 22-24) and discuss their substitution pattern together with 9 known species (1, 3, 6-10, 13, 21). The results which are partly unexpected are put together phenomenologically. We have no reasonable explanation for some results, i.e. only a few substituents with „complementary“ properties like the pair CH2OH/Br or CH3/CN in compounds 16 and 18, respectively, prefer a vicinal arrangement at a double bond.
    Notes: Wir berichten über 15 neue disubstituierte Bullvalene (2, 4, 5, 11, 12, 14-20, 22-24) und diskutieren ihr Substitutionsmuster gemeinsam mit dem von 9 bekannten Vertretern (1, 3, 6-10, 13, 21). Die teilweise unerwarteten Ergebnisse werden phänomenologisch geordnet. Für einige Befunde fehlen befriedigende Erklärungen. So bevorzugen z. B. nur manche Substituenten mit „komplementären“ Eigenschaften wie das Paar CH2OH/Br oder CH3/CN in den Verbindungen 16 bzw. 18 eine vicinale Anordnung an der Doppelbindung.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861190724
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