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
  • 1
    Electronic Resource
    Electronic Resource
    Polyxanthylic acid: structures of the ordered forms (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 3077-3087 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present evidence for structures of two ordered forms of polyxanthylic acid based on ir spectroscopy, pH titrations, and thermal transitions. Over the pH range ∼6-9.5, the structure is a four-stranded helix with alkali metal ions specifically complexed in the central channel. These internal counterions stabilize the structure by complexing with carbonyl oxygens and by partial screening of electrostatic repulsion caused by ionization of the xanthine residues in this pH range. Below pH 5, the structure is quite different and much more stable. Our data are consistent with a six-stranded helix in which both carbonyl oxygens and both NH protons are hydrogen bonded.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360181213
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Ordered forms of 5′-8-aminoguanylic acid (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2095-2106 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5′-8NH2GMP forms an ordered structure in moderately acid (pD 4.7) solution. We propose for this ordered form a novel hemiprotonated G·G structure with a twofold rotation axis and three hydrogen bonds between each pair of guanine residues. Gel formation does not occur with this nucleotide in either neutral or acid solution. In neutral solution 5′-8NH2GMP also forms a regular, ordered structure, quite different from the acid form and similar to that formed by 5′-GMP under the same neutral conditions. We suggest that this ordered structure consists of a regularly stacked array of planar tetramers, similar to that proposed for 3′-GMP at pH 5.2
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360141009
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Circular dichroism of helices formed by purine monomers with pyrimidine polynucleotides (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 709-722 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The CD spectra of a number of helical complexes formed by purine monomers and complementary pyrimidine polyribonucleotides have been observed over the range 200-400 nm. Each of these spectra is quite similar to that of the corresponding polymer-polymer helix. The spectra are evidently determined by the geometry of the asymmetric array of bases, largely unperturbed by the ribose-phosphate backbone. The helix structure (A-form), on the other hand, is determined by the backbone of the pyrimidine homopolymer. Data on the monomer-polymer complexes support the conclusion that the CD spectra of ribohomopolymer helices depend primarily on interastrand interactions of the same transition within a given base and are relatively unaffected by transitions of the complementary base.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180315
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The structure of triple-stranded G·2C polynucleotide helices (1976)
    New York : Wiley-Blackwell
    Biopolymers 15 (1976), S. 523-531 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal stability of a new polynucleotide complex has been used to establish the hydrogen-bonding structure of three-stranded C-G·CH+ helices. In the Hoogsteen structure, the 8NH2 group of 8NH2GMP can form a third hydrogen bond to the CH+ strand, but in the alternative structure, the 8NH2 group can form no interbase hydrogen bonds. For the new complex, 8NH2GMP·2 poly(C), a transition temperature of 80°C is observed under conditions in which the corresponding complex formed with 5′-GMP has a Tm of 20°C. We conclude from this 60° elevation of transition temperature that a third hydrogen bond is formed by the 8NH2 group and that the structure must have Hoogsteen bonding. In order to be compatible with this structure in regular helices formed by U,C copolymers, A·2U bonding would also have to have a Hoogsteen structure.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1976.360150309
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Stable and metastable forms of poly(G) (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 791-809 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(G) is shown by ir spectroscopy to be capable of existence in a metastable form which is converted spontaneously at ambient temperature, or more rapidly on heating, to a stable form. The metastable form can be regenerated by freezing and thawing the solution.The high-charge density of four-stranded poly(G) makes it especially susceptible to electrostatic destabilization by use of Et4N+ counterions, which screen electrostatic repulsion of multiple strands less effectively than alkali metal ions. Poly(G) has been obtained for the first time in the single-stranded form in aqueous solution and shown to undergo a fully reversible helix-coil transition on heating.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160407
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Residence time distribution in twin-screw extruders (1975)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 15 (1975), S. 437-443 
    Details
    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: Twin screw extruders are finding increased usage in reacting and devolatilizing applications. Using self-wiping profiles, the twin screws fulfill the requirement that there be no “dead” or “unmixed” zones. Agitator design must be chosen with care so that a reasonable balance can be obtained between forwarding rate, surface-generation rate, vapor passageway, power, and axial mixing. Techniques have been developed for measuring residence time distributions and characterizing axial flow behavior. The method also permits direct determination of the holdup in starved barrel applications. Data on residence time distribution are presented for 4-in. diameter twin screw equipment with a variety of rotor configurations.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760150607
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Twin screw reinforced plastics compounding (1978)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 321-325 
    Details
    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: Co-rotating, self-wiping twin-screw equipment has been developed which incorporates fiber glass or fillers into various plastics to form compounds with superior mechanical properties. Fiber glass bundles are folded into the plastic melt in such a fashion that each glass strand is wetted out with minimum breakage of the strand. The intensity of compounding is controlled externally to condition the basic polymer for optimum filler incorporation. The external control permits compounding a wide variety of plastics over a range of throughputs. The degree of mixing can be varied while the machine is in operation. The fiber resin blend passes through an independently controlled extruder for pelletizing with a hot die face cutter. Either air or water quench systems can be used for cooling the pellets. The gentle handling of the fiber resin blend through compounding and extrusion not only minimizes glass breakage, but also minimizes wear on the equipment. Retention of glass fiber length and good strand bonding impart superior properties to the fiber resin product.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760180414
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Production of levoglucosan and glucose from pyrolysis of cellulosic materials (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 3525-3539 
    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: Vacuum pyrolysis of cellulose within the temperature range of 300-500°C provides a tar fraction containing mainly levoglucosan and glucose condensation products. It was found that pyrolysis proceeds at a much faster rate at the higher temperatures without detrimental effect on the yields. At 400°C the reaction was essentially complete within 3 min yielding a tar that contained 39% levoglucosan and, upon mild acid hydrolysis, gave 49% D-glucose. The yields could be further improved by washing or treatment of cellulosic substrates with acids. Cotton hydrocellulose provided up to 58% levoglucosan or 77% D-glucose. This is the highest yield determined by unequivocal methods. Commonly available cellulosic materials such as wood and newsprint give very poor yields of levoglucosan. However, the yields could be improved substantially by acid washing or prehydrolysis to the extent that pyrolysis of these substrates may become an attractive industrial process. The data in this report provide the technical basis for such a process and resolve the existing controversies on the reported yields.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070231209
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Statistical analysis of nitrogen-containing vinyl copolymers: Radiation-induced copolymerization of vinyl acetate and N-vinyl-2-pyrrolidone (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 2159-2167 
    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: Radiation-induced copolymerization of vinyl acetate and N-vinyl-2-pyrrolidone was carried out at 5°C using γ-irradiation of 1450 rads/min. Copolymers prepared at conversions lower than 5% were analyzed by a saponification technique. Various linear and nonlinear statistical analysis techniques were used to determine the reactivity ratios of this system as r1 = 0.348 and r2 = 3.108. These data were examined and analyzed in relation to problems of elemental analysis involving nitrogen-containing copolymers and to discrepancies in the reactivity ratios obtained by previous investigators. The presence of oxygen and a higher dose rate did not affect the copolymer composition within statistical error. Hydrolyzed copolymers prepared by this method have potential applications as biocompatible materials.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070241008
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Hyaluronidase-bound membrane as a biomaterial for implantable fuel cells (1976)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 10 (1976), S. 283-294 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A new biomaterial containing covalently bound hyaluronidase was prepared. An application of this enzyme membrane is to improve the performance of an implantable fuel cell. Hyaluronic acid is a contributor to the viscosity of tissue fluids but can be a potential fuel source because of its sugar content. The incorporation of immobilized hyaluronidase would not only contribute to a more available fuel supply by splitting hyaluronic acid but, perhaps more importantly, enhance the rate of mass transport of fuel, O2, and reaction products by reducing the viscosity near the electrode membranes. Hyaluronidase was bound to Sepharose gel and its thermoplastic membrane after activation by cyanogen bromide. Fourteen and 22% of the activities were recovered from the gel and membrane, respectively. The activity of the bound enzyme was stable for six months at 0°C. The addition of hyaluronic acid, 1 mg/ml, to a typical implantable type bioautofuel cell in vitro increased external solution viscosity from 1.1 to 2.5-2.8 cP and reduced voltage output under 10 kΩ by 60% in 3 hr. When the hyaluronidase bound membrane was placed at the anode, viscosity of the glucose-hyaluronic acid solution was lowered to 1.8 cP and the cell output increased to the original level of a glucose-fueled cell in 3 hr. Glucosamine-equivalent released from hyaluronic acid at the electrode was 3.1 mg after 22.5 hr. This represents 90% of the theoretical consumption. Restoration of the cell output was probably a combination of the enhanced transport of fuel, O2 and products, and/or appearance of a new fuel, glucosamine-equivalent.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820100209
    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...