ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • GEOPHYSICS  (67)
  • Polymer and Materials Science  (28)
  • Geophysics
  • PROPELLANTS AND FUELS
  • 1990-1994  (72)
  • 1975-1979  (31)
  • 1
    Electronic Resource
    Electronic Resource
    Base stacking in A fluorescent dinucleoside monophosphate: εApεA (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 1361-1372 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The optical properties of the 1,N6 - etheno derivative of ApA (εApεA) have been studied. Absorbance and CD measurements suggest that (1) neutral salts tend to unstack this molecule and (2) the stacking interaction is weaker than in ApA. εApεA is found to be quenched strongly with respect to the monomer. (εAMP); this quenching is solvent dependent (1M NaCl 〉 5M NaClo4〉40%glycerol) and increases with the ratio of temperature to viscosity (T/η) in each case. Fluorescence lifetime measurements also reveal a temperature- and solvent-dependent decay which is nonlinear on a semilog plot. In the presence of 95% glycerol, this decay return to linearity. These data have been considered from two points of view: (1) two-state pictures which are based on thermodynamic least-squares fit to quatum yield and CD curves, together with two exponential fits to the decay curves and (2) a dynamical model in which relatives fluorophore motion leads to deexcitation via intramolecular collision. A simple model of type (2) gives qualitative agreement with the observed behavior.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1978.360170519
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Melanin-concentrating hormone: A structural and conformational study based on synthesis, biological activity, high-field nmr, and molecular modeling techniques (1990)
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 609-622 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of Melanin-concentrating hormone (MCH) fragments have been synthesized and their biological activities compared with the parent peptide. The substructural units, 5-14 linear and 5-14 cyclic, have been used as models for MCH -  in 1H-nmr conformational studies. Conformational features predicted by molecular dynamics analyses find support in the nmr experiments.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360290314
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Infrared spectroscopic studies on polyethylene, 5Part 4: cf.1.. The measurement of chain branching on powder polyethylene specimens (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 975-987 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The scope and limitations of the potassium bromide disc technique for the infra-red determination of chain branching in small samples of polyethylene in powder form have been assessed. Many of the samples encountered have an average particle size, prior to grinding with potassium bromide, of about 100 μm and very satisfactory results have been obtained, but the presence of larger particles leads to poor quality discs and inferior results. The well established double beam technique proves suitable for removing the interfering methylene absorption and compensation with polymethylene in the form of a film rather than as a pressed disc is preferable. Difficulties were encountered in preparing branching standards in a uniform and fine powder form, to avoid variation of the absorption coefficient of the 1 378 cm-1 methyl band with particle size. Such powders are best obtained by precipitation from solution rather than by low temperature milling. Despite these problems chain branching measurements may be made with a precision of between 5 and 10% and an accuracy of about 15%.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800414
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Infrared spectroscopic studies on polyethylene, 1. The measurement of low levels of chain branching (1976)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 437-448 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Probleme, die bei Anwendung der Kompensationsmethode auf IR-spektroskopische Bestimmungen von niedrigen Verzweigungsgraden in Polyäthylenen hoher Dichte auftreten, werden systematisch untersucht. Die erzielbare Genauigkeit wird bestimmt und es wird gezeigt, daß, wenn möglich, eine Korrektur für die Methyl-Endgruppen angewendet werden sollte. Diese ist bei einigen Polymertypen leicht möglich, bei anderen hingegen schwieriger. Als Kompensationskeil im Referenzstrahl des Spektrometers verwendet man besser Polymethylen als hochmolekulares Polyäthylen. Die äußerste Empfindlichkeit, die mit der manuellen Kompensationsmethode erreicht werden kann, liegt bei einem Methylzweig pro 2000 C-Atome. Wenn diese Methode jedoch ergänzt wird durch Computer-Kurvendämpfung und Computer Mittelung über zahlreiche Momentspektren (“C.A.T.”), kann noch eine deutliche Verbesserung im Signal-Rausch-Verhältnis erzielt werden. Damit wird es möglich noch Verzweigungsgrade bis herunter zu 0,1 Methylgruppen pro 1000 C-Atome zu messen.
    Notes: The problems encountered in the infrared spectroscopic estimation of the low levels of chain branching present in high density polyethylene, using the compensation method, are discussed systematically. The precision to be expected has been determined and it is shown that, if possible, a correction should be applied for methyl groups present at the chain ends. This is feasible with some types of polymer but more difficult with others. The compensating wedge in the reference beam of the spectrometer should be made of polymethylene rather than a high molecular weight polyethylene. The ultimate sensitivity of the manual compensation method is about one methyl branch per two thousand carbon atoms. However, when this is supplemented by computer smoothing and off-line computation of average transients (C.A.T.), a significant improvement is obtained in the signal to noise ratio, and branching levels down to 0,1 methyl groups per thousand carbon atoms are readily measured.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1976.021770212
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Use of auger and x-ray photoelectron spectroscopy to study the locus of failure of structural adhesive joints (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 2375-2392 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: The techniques of Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) have been used to study the locus of failure of epoxy resin joints. The effects of a long water immersion and the application of a silane-based primer have also been studied. Results indicated that for dry joints fracture occurred near an epoxy resin/metal interface while with water-soaked unprimed joints, fracture occurred interfacially between the adhesive and iron oxide. The application of the primer to the metal surface prior to bonding prevented the formation of a water-formed oxide although fracture was then found to occur through the primer.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210907
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Computer optimization of reverse osmosis processing of soy whey with cellulose acetate modules (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 749-762 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: In processing full-fat soy flour to an acid-precipitated lipid protein concentrate a byproduct whey fraction results which, because of its high biological oxygen demand, represents a serious disposal problem. Processing of food waste streams by reverse osmosis has received considerable attention because of its low theoretical energy requirement since no phase change is involved. In a previous study at this Center a mathematical model was developed for the diffusive transport of soy lipid protein concentrate whey across cellulose acetate membranes. In this study, pumping energy and power costs combined with membrane life and replacement costs were incorporated into the original model to provide a basis for optimization from an energy cost standpoint. Computer-simulated runs were compared with experimental pilot-plant runs, and the agreement between predicted and actual results was quite good. Water flux rates were in the range of 3 to 7 gal/ft2/day. Computer runs were used to optimize the processing of 100,000 gal/day of soy whey at 8000 ppm biological oxygen demand (BOD). Costs were at a minimum with a six-stage tapered flow primary reverse osmosis treatment over a porous cellulose acetate membrane, followed by a six-stage tapered flow reverse osmosis over a tighter membrane. BOD reduction was 94% at a cost of $5.45/1000 gal.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070240312
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Chemical reactions and reactivity of primary, secondary, and tertiary diamines with acid functionalized polymers (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 1589-1600 
    Details
    ISSN: 0887-624X
    Keywords: reactivity ; amines ; functional polymers ; anhydride ; carbonxylic acid ; crosslink ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactive melt processing of different types of diamines with polyethylene containing carboxylic acid groups and polystyrene containing anhydride groups was carried out. The reactivity of primary, secondary, and tertiary diamines with these acid polymers was determined using various techniques. Molecular weight increases due to crosslinking were observed through (1) changes in the torque during the reactive processing, (2) decrease in melt flow indices, and (3) decrease in solubility of the reaction products. The chemical compositions of the reaction products were examined by Fourier transform infrared (FTIR) spectroscopy. Thermal analysis using differential scanning calorimetry (DSC) was carried out to determine the crystallization behavior, glass transition temperatures, and thermal stabilities of the reaction products. Results show that the primary amine is the most reactive towards carboxylic acid or anhydride groups followed by the secondary and then the tertiary amine. Anhydride groups on polymers are of higher activity towards secondary or primary amino groups than carboxylic acid groups in the nucleophilic acyl substitution reactions. Reaction products crosslinked with the primary diamine are less stable than their parent acidic polymers. On the other hand, crosslinking with the secondary or tertiary diamine gives products with higher thermal stability than the parent acidic polymers. The formation of reversible and irreversible crosslinks with different types of diamines is also reported. © 1992 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300811
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    A systematic nomenclature for cascade polymers (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 641-651 
    Details
    ISSN: 0887-624X
    Keywords: cascade polymers ; dendritic polymers ; arborols ; dendrimers ; starburst polymers ; nomenclature ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cascade (dendritic) polymers are discrete, highly branched, monodisperse polymers that possess branching patterns described by a mathematical progression. A systematic nomenclature that accurately represents these molecules is described. © 1993 John Wiley & Sons, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310307
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Effect of reaction conditions on the grafting of 2-(dimethylamino)ethyl methacrylate onto hydrocarbon substrates (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1691-1702 
    Details
    ISSN: 0887-624X
    Keywords: grafting ; basic functionalization ; free radical polymerization ; methacrylate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The grafting of 2-(dimethylamino)ethyl methacrylate (DMAEMA) onto two model hydrocarbons, squalane and n-eicosane, and to linear low density polyethylene (LLDPE) has been investigated. The results of the study indicate that a high reaction temperature, 160°C, and a low concentration of monomer, less than 0.3 M, are optimum conditions for the grafting reaction. Reaction products, which consisted of grafted hydrocarbons and poly(DMAEMA), were separated by solvent extraction and vacuum distillation; samples were then analyzed by NMR and FTIR spectroscopy and size exclusion chromatography. 1H-NMR spectroscopy indicates that grafted squalane contained approximately 6 DMAEMA units per squalane residue. 1H- and 13C-NMR and molecular weight studies strongly suggest that the grafts onto the model hydrocarbons consist of single DMAEMA units. Results of the melt grafting of DMAEMA onto LLDPE show that the grafting efficiency and degree of grafting are substantially lower than were expected from the model system. © 1994 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080320911
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Grafting of 2-(dimethylamino)ethyl methacrylate on linear low density polyethylene in the melt (1990)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 181 (1990), S. 1-22 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Das Pfropfen von 2-(Dimethylamino)ethyl methacrylat (DMAEMA) auf lineares Polyethylen niedriger Dichte (LLDPE) in der Schmelze wurde mittels Messungen des Monomerumsatzes, des Pfropfgrades und der Pfropfeffizienz untersucht. Die Ergebnisse zeigen, daß das Pfropfen von DMAEMA auf LLDPE bereits bei niedrigen Temperaturen von etwa 90°C in der Schmelze durchgeführt werden kann, obwohl der Schmelzpunkt von LLDPE bei etwa 120°C liegt. Wenn die Pfropfreaktion bei zu hohen oder zu niedrigen Temperaturen durchgeführt wird, kann nur ein sehr niedriger Pfropfgrad beobachtet werden. Hohe Reaktionstemperaturen begünstigen die Polymervernetzung, was sich im Absinken des Schmelzindex bemerkbar macht. Die meisten Pfropfvorgänge werden während der Anfangsphase der Reaktion (unter den vorliegenden Bedingungen während der ersten 3 min) beobachtet. Eine Verlängerung der Reaktionsdauer über diesen Zeitraum hinaus führt zu verstärkter Vernetzung und erhöhter Produktion des Homopolymeren, was die Effizienz des Prozesses verringert. Organische Peroxide sind über einen weiten Halbwertszeitenbereich effektive Initiatoren der Pfropfreaktion, während Azoinitiatoren keine Pfropfung bewirken.
    Notes: Grafting of 2-(dimethylamino)ethyl methacrylate (DMAEMA) on linear low density polyethylene (LLDPE) in the melt has been studied through measurements of monomer conversion, the degree of grafting and the grafting efficiency. Results show that the grafting of DMAEMA on LLDPE can be carried out in the melt at temperatures as low as 90°C even though the melting point of the LLDPE is as high as 120°C. When the grafting reaction is carried out at too low or too high temperature, a low degree of grafting is observed. High reaction temperature favoured crosslinking of the polymer as indicated by decreasing melt flow index. Most of the grafts were obtained during the early period of the reaction (before 3 min under the reaction conditions used). Further increase in reaction time increased crosslinking and also produced more homopolymer, thus decreasing the grafting efficiency. Organic peroxides are effective initiators for the grafting reaction over a broad range of half-lives while azo initiators do not produce grafting.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1990.051810101
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...