Library

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
    The infuence of interchain compositional heterogeneity on the conformation in random copolymers of γ-benzyl-L-glutamate and L-valine (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 2851-2864 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Variation in the solvent used for the copolymerization of γ-benzyl-L-glutamate and L-valine N-carboxyanhydrides provides copolymers which have variable interchain compositions, and this variation in interchain compositional heterogeneity is reflected in the solid-state conformations of the respective copolymers. Poly[Glu(OBzl)29Val71] prepared in dioxane exhibits a β-structure, whereas a copolymer of the same average composition prepared in benzene/methylene chloride shows predominantly an β-helix conformation with a small amount of β-structure. The use of the monomer reactivity ratio permits the calculation of the average and incremental copolymer compositions at any conversion; thus, correlations between conformation and interchain compositional heterogeneity can be made. In general, copolymers prepared in dioxane show a greater distribution of chain composition and therefore permit a wider variety of conformation than copolymers prepared in benzene/methylene chloride under identical conditions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1978.360171208
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The random copolymerization of γ-benzyl-L-glutamate and L-valine N-carboxyanhydrides: Reactivity ratio and heteogeneity studies (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 2835-2849 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The random copolymerization of the N-carboxyhydrides of γ-benzyl-L-glutamate and L-valine using triethylamine as the initiator in low dielectric media reults in high-molecular-weight copolymers at low convenrson. This behavior makes it possible to apply the monomer reactivity ration theory, which was dervied for addition polymerizations, and from the use of the copolymer composition equation, the respective monomer reactivity ratios, the average and incremental copolymer compositions, and the monomer feed ratio at any conversion can be determined. A comparison of the reactivity ratios for the copolymerization of γ-benzyl-L-glutamate NCA and L-valine NCA in benzene/methylene chloride (rG = 2.1, rV = 0.6) with those obtained using dioxane (rG = 2.7, rV = 0.3) indicates that the interchain compositional heterogeneity is greater for copolymers prepared in the dioxane. For Example, at 100% conversion of the monomeric NCAs, Poly[Glu(OBzl)50Val50] prepared in dioxance has an interchain composition ranging from 74 to 0 mol % γ-benzyl-L-glutamate, whereas in benzene/methylene chloride the interchain composition of γ-benzyl-L-glutamae ranges from 65 to 0 mol %. Once the reactivity ratios are obtained for any pair of α-amino and N-carboxyanhydrides, the use of the aforementioned parameters relating to interchain composition can give insight into the compositional heterogeneity between chains as a function of conversion and provide a basis for the preparation of random α-amino acid copolymers that are homogeneous.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1978.360171207
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Microheterophase structure, permeability, and biocompatibility of A-B-A triblock copolymer membranes composed of poly(γ-ethyl L-glutamate) as the A component and polybutadiene as the B component (1985)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 19 (1985), S. 1135-1155 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A-B-A block copolymers (EBE) consisting of poly(γ-ethyl L-glutamate) as the A component and polybutadiene as the B component were synthesized. The microheterophase structure of these block copolymers, as observed microscopically, was less distinct than that of the block copolymer (GBG) composed of poly(γ-benzyl L-glutamate) as the A component. This was attributed to the better compatibility of the ethyl group with polybutadiene block, compared with the benzyl group. The observed micelle size of various microheterophase structures ranged from 350 to 480 Å, which agreed well with the micelle size estimated from a thermodynamic study. From the measurement of water permeation through the EBE block copolymer membranes, the contributions of the interfacial region between the α-helical polypeptide domain and polybutadiene domain to the permeability coefficient were concluded to be higher than those of poly(γ-methyl L-glutamate)-polybutadiene block copolymer (MBM) membranes, i.e., more hydrophilic domain seemed to exist in EBE membranes than in MBM membranes. The results of in vivo tests on the tissue compatibility indicate that the EBE block copolymer membranes have good biocompatibility.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820190921
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Ca, P-rich layer formed on high-strength bioactive glass-ceramic A-W (1990)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 24 (1990), S. 331-343 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Glass-ceramic A-W, containing crystalline apatite and wollastonite in a MgO—CaO—SiO2 glassy matrix shows high bioactivity as well as high mechanical strength, but other ceramics containing the same kinds of crystalline phases in different glassy matrices do not show the same bioactivity. In order to investigate the bone-bonding mechanism of this type of glass-ceramic, surface structural changes of the glass-ceramics after exposure to simulated body fluid were analyzed with various techniques. A solution with ion concentrations which are almost equal to those of the human blood plasma was used as the simulated body fluid, instead of Tris-buffer solution hitherto used. For analyzing the surface structural changes, thin-film x-ray diffraction was used in addition to conventional techniques. It was found that a bioactive glass-ceramic forms a Ca, P-rich layer on its surface in the fluid but nonbioactive ones do not, and that the Ca, P-rich layer consists of carbonate-containing hydroxyapatite of small crystallites and/or defective structure. These findings were common to those of Bioglass-type glasses. So, we conclude that the essential condition for glass and glass-ceramic to bond to bone is the formation of the surface apatite layer in the body environment but it is not essential to contain apatite within the material. Bioactivity of glass and glass-ceramic can be evaluated in vitro by examining the formation of the surface apatite layer in the simulated body fluid described above.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820240306
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Evaluation of correction accuracy of several schemes for AES matrix effect correctionsPaper presented at ECASIA 89, Antibes, France, 23-27 October 1989. (1990)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 15 (1990), S. 466-472 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A matrix effect correction is required to improve the accuracy of quantitative AES analysis. The correction includes terms involving the atomic density (n), electron back-scattering factor (R) and electron escape depth (L). Many schemes have been proposed by various people for corrections of the R and L terms. However, up to now, there have been no systematic investigations of the correction accuracy of the proposed schemes. We have evaluated the correction accuracy, based on measured intensity data for Au—Cu alloys of different compositions. Comparison was made between the observed intensity ratio K (=Iunk/Istd) and the calculated intensity, ratio K′ (= C(nunk/nstd)(Runk/Rstd)(Lunk/Lstd)), where C and I represent the concentration and intensity, respectively. The superscripts ‘unk’ and ‘std’ denote that the parameters are for unknown and standard specimens, here the pure elements. If the correction works well, the error Er (= K′ — K)/(K) will become smaller. Evaluations were carried out on three schemes for the R correction and on seven schemes for the L correction using the Au 239 eV, Au 2024 eV and Cu 920 eV transitions. The root mean square (RMS) of the calculated errors showed several per cent for the best case and 20-30% for the worst case. The RMS error varied a few per cent between schemes for the R correction but it varied ∼30% for the L correction.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740150805
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    The reliability of quantitative analysis with AES (1990)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 16 (1990), S. 140-143 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The Japanese VAMAS-SCA working group is composed of 19 institutes. Three kind of Au—Cu alloys (Au 75 at.-%-Cu 25 at.-%, Au 50 at.-%-Cu 50 at.-%, Au 25 at.-%-Cu 75 at.-%) were prepared, and these specimens, pure Au and pure Cu were distributed to the members of the VAMAS-SCA working group. The surface concentrations of these alloys were calculated from the Auger peak amplitudes in two ways. One method used the published relative sensitivity factors, and the other used pure Au and Pure Cu as the standard materials. The mean values of the surface concentrations calculated with the published relative sensitivity factors were almost the same as those calculated with the standard materials. This means that the published relative sensitivity factors are reliable to some extent. The error of the surface concentration calculated with pure Au and pure Cu as the standard materials lay between about 3% and 10%, and that with the relative sensitivity factors lay between about 7% and 20%. The calculated surface concentrations of Au were larger than the bulk concentrations of Au when the matrix effect was neglected.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740160127
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Quantitative surface chemical analysis of Au—Cu alloys with aes (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 12 (1988), S. 125-130 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The Japanese VAMAS-SCA working group is composed of 19 institutes. Three kinds of Au-Cu alloys (Au25 at%-Cu75 at%, Au50 at%-Cu50 at%, Au75 at%-Cu25 at%) were prepared, and these specimens were distributed to the members of Japanese VAMAS-SCA working group and Auger peak amplitude ratios were measured to clarify the correlation factor of different types of spectrometers. The comparison was carried out by using the relative sensitivity factor for Au and Cu. The relative sensitivity factor for lower energy varied from spectrometer to spectrometer, but that for higher energy did not vary so much. Therefore, to carry out the inter-laboratory comparison of the data, the transfer of the data of peak amplitude at higher energy should be recommended.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740120212
    Library Location Call Number Volume/Issue/Year 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...