ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

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
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1435-1536
    Keywords: Controlled release of drug ; capsule ; poly(α amino acid)s ; membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The release behavior of a water-soluble drug through membranes made of poly(L-leucine) and its copolymer with different hydrophilic properties was studied. The effect of casting methods on the release rate was also investigated. It was found that the membrane with a higher hydrophilic property resulted in a higher permeation rate. The capsule was prepared as a composite sheet from a poly(L-leucine)-prednisolone 21-sodium succinate sponge and a poly(L-leucine) membrane. Release of the water-soluble drug from the capsule was found to be effectively governed by the hydrophilic character and thickness of the outer membrane. Biocompatibility studies carried out by implanting the poly(L-leucine) sponge subcutaneously in the dorsal surface of the rat showed that the sponge had a good biocompatibility and slow biodegradation. It was concluded from these results that poly(L-leucine) should be a suitable material for preparing a controlledrelease drug device for long-term dosage.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1435-1536
    Keywords: Radical polymerization ; propagating polymer radical ; EPR spectrum ; poly(ethylene glycol)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The polymerization of di-2[2-(2-methoxyethoxy)ethoxy]ethyl itaconate (1) with dimethyl 2,2′-azobisisobutyrate (2) was studied, in benzene, kinetically and spectroscopically with the electron paramagnetic resonance (EPR) method. The polymerization rate (R p) at 50°C is given by the equation:R p=k[2]0.48 [1]2.4. The overall activation energy of polymerization was calculated to be 34 kJ·mol−1. From an EPR study, the polymerization system was found to involve EPR-observable propagating polymer radicals of 1 under the actual polymerization conditions. Using the polymer radical concentration, the rate constants of propagation (k p) and termination (k t) were determined. With increasing monomer concentration,k p(1.5∼4.3 L·mol−1·s−1 at 50°C) increases andk t (1.0·104∼4.2·104 L·mol−1·s−1 at 50°C) decreases, which seems responsible for the high dependence ofR p on the monomer concentration. The activation energies of propagation and termination were calculated to be 11 kJ·mol−1 and 84 kJ·mol−1, respectively. For the copolymerization of 1(M 1) and styrene (M 2) at 50°C in benzene the following copolymerization parameters were found:r 1=0.2,r 2=0.53, Q1=0.57, ande 1=+0.7.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1435-1536
    Keywords: Reversed micelle ; oligomer of L-lysine ; circular dichroism measurement ; conformational transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of the chain length on the conformation of oligo-L-lysines (Lys-n, n= 9, 12 and 15) was examined in the reversed micelles of bis(2-ethylhexyl)sodium sulfosuccinate (AOT) in octane by the circular dichroism (CD) measurements. These oligomers seem to take aβ-structure in these systems. The structure-inducing effect of the reversed micelles is enhanced as the molar ratio of water to AOT (w0=[H2O]/[AOT]) becomes smaller. On the other hand, in the aqueous solutions the oligomers having 12 and 15 residues show the conformational transition from random coil toα-helical structure by the addition of AOT, but the short oligomer of 9 residues does not show such a conformational transition.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1435-1536
    Keywords: Adsorption ; L-lysine ; oligo(L-lysine) ; poly(L-lysine) ; poly(methacrylic acid) gel ; swelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Poly (methacrylic acid) gels (PMAA gels) of various degrees of crosslinking were prepared and the dissociation behavior of these gels was examined; the swelling behavior was investigated as a function of the solution pH values. A reentrant phenomenon of swelling was observed and interpreted based on the Flory-Huggins equation and the Donnan equilibrium formula. Moreover, adsorption of L-lysine, oligo(L-lysine)s (Lys-n,n=3, 9, and 19) and poly(L-lysine) onto PMAA gels from aqueous solutions was investigated under different conditions of pH and concentration of adsorbate. The adsorption ratio of L-lysine onto PMAA gel is dependent on both the pH of solution and the degree of crosslinking. In a pH range between 8 and 9, the protonated form of L-lysine is strongly adsorbed on the PMAA gel by electrostatic interactions. Oligomers and polymer of L-lysine are adsorbed in a somewhat different way from the monomeric L-lysine. In addition, the desorption behavior of L-lysine from PMAA gels by a change in pH was also investigated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1435-1536
    Keywords: Copoly (N 5-ω-hydroxyalkyl-L-glutamine-L-glutamic acid) ; Solvent-induced conformational change ; pH-induced conformational change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Copoly (α-amino acid)s consisting ofL-glutamic acid residue andN 5-ω hydroxyalkyl-L-glutamine residue, i.e., 2-hydroxyethyl, 3-hydroxypropyl, and di-2-hydroxyethyl derivatives were prepared by the reactions of copoly (L-glutamic acid) containing succinimide ester with corresponding amino alcohols. The conformation of these copolymers was examined by the CD and infrared measurements. These three copolymers containing about 20–30% hydroxyalkyl groups undergo a methanol-induced and a pH-induced conformational transitions. The copolymer containing about 50% 3-hydroxypropyl group assumes the α-helical conformation in the pH region from 2.5 to 11.6, and in a methanol-water mixture (9∶1). On the other hand, the copolymer containing about 60% di-2-hydroxyethyl groups does not allow any helical conformation even at lower pH and also even in a trifluoroethanol-water mixture (9∶1), suggesting that the branched hydroxyalkyl group is unfavorable for the formation of α-helix. Furthermore, the poly(N 5-di-2-hydroxyethyl-L-glutamine) is shown to have a rather disordered structure in the solid state.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1435-1536
    Keywords: Reversed micelle ; horseradishperoxidase andoxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The enzymatic activities of horseradish peroxidase solubilized in reversed micelles of bis(2-ethylhexyl)sodium sulfosuccinate formed in octane at variousΩ o values (Ω o=[H2O]/[AOT]) were investigated by studying the catalytic oxidation of hydroquinone and p-cresol. These enzymatic reactions obeyed Michaelis-Menten kinetics. The turnover number of the enzymatic reaction of hydroquinone solubilized in the water pool increased with a decrease inΩ o value. On the other hand, the dependence of the turnover number of the enzymatic reaction of p-cresol solubilized in octane on theΩ o value was similar to that in the case of hydroquinone, although even at higherΩ o values the turnover number was smaller than that in water. Furthermore, it was suggested by spectrophotometric and circular dichroism measurements that the conformational change of enzyme induced the change in enzymatic activity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1435-1536
    Keywords: Reversed micelles ; spiropyran ; photochromic ; transport ; liquid membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In a reversed micellarn-decane solution, a spiropyran derivative 3′,3′-dimethyl-1′-octadecyl-6-nitrospiro(2H-benzopyran-2,2′-indoline) (PC18) showed normal photochromism, and the reversed micelles provided polar microenvironment increasing stability of a zwitterionic merocyanine (MC) form of PC18. Though the reversed micelles of tetraethyleneglycol dodecylether (TEGDE) alone inn-decane had relatively low ability to extract amino acid from aqueous solutions, the PC18-incorporated TEGDE reversed micelles inn-decane showed good photo-controlled extraction of zwitterionic amino acid under UV-irradiation and release under VIS-irradiation. Extent of the extracted amino acid was higher for tryptophane (Trp) bearing hydrophobic side chain than alanine (Ala), showing amino acid selectivity. Photo-driven active transport of amino acid across a liquid membrane was attained by the PC18-incorporated TEGDE reversed micellar carrier in a water/n-decane/water three-phase system, where one side of an aqueous/organic interface was irradiated by the UV-light and the other side by the VIS-light. When Trp and Ala were present in the aqueous solution, Trp was selectively transported.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1435-1536
    Keywords: Reversed micelle ; poly(N5-Ω-hydroxyalkyl-L-glutamine)s ; circular dichroism measurement ; conformational transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The molecular conformations of poly(N5-dihydroxyethylaminopropyl-L-glutamine) and poly(N5-dihydroxyethyl-L-glutamine) were investigated in reversed micelles of AOT as well as in aqueous solutions. Both poly(α-amino acid)s assume disordered structures in pure water. The conformation of poly(N5-dihydroxyethylaminopropyl-L-glutamine) transits intoα-helix in the reversed micelles as the molar ratio of water to AOT (w0=[H2O]/[AOT]) becomes smaller. A similar conformational transition was also observed in aqueous solutions when a certain amount of AOT was added. Under these conditions, however, poly(N5-dihydroxyethyl-L-glutamine) did not undergo a conformational transition intoα-helix.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The formation of carboxylic acid groups (carboxyl + ester groups) was found in a threephase reaction of crosslinked poly(chloromethylstyrene) beads with an excess amount of sodium nitrite in immiscible solvents of benzene and water with tetrabutylammonium bromide as a phase transfer catalyst (PTC), and the dependence of carboxylic acid yield on the experimental conditions was studied. The product contains hydroxyl groups and ester bonds besides carboxyl groups. It was tentatively considered that the carboxyl groups are produced by direct oxidation of chloromethylstyrene groups by nitrous anions. Nitrous anions do not only act as a nucleophile but also as an oxidative reagent in this case.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...