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  • 1
    ISSN: 0922-338X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-904X
    Keywords: bioeliminable surfactants ; amphiphilic properties ; MPOE coating ; microspheres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The objective of this work is to prepare microspheres by the emulsion-solvent evaporation process using MPOE-PLA copolymers as the matrix material and/or the surfactant. This preparation was studied in order to avoid the use of PVA as the surfactant in the process. Methods. Two series of MPOE-PLA copolymers were synthesised. The first, with a long and constant length PLA chain (45,000 g.mol-1), was used as the matrix material, the second, with short PLA chains (≤ 2,200 g.mo1-1), and different HLB as the surfactant. Microspheres were prepared by the "simple” and "double” emulsion methods. The steric stabilization effect of the copolymers was investigated using confocal microscopy and X-ray photoelectron spectroscopy (XPS). Results. Confocal microscopy and XPS analysis showed that the microspheres prepared using MPOE5K-PLA0.5K as the surfactant and MPOE-PLA45K copolymers as the matrix material had an MPOE coating present at the microsphere surface. This hydrophilic layer ensures steric stabilization of the particles. Conclusions. MPOE-PLA copolymers can be used for the preparation of particles instead of PVA and their use can be extended whenever a biocompatible and bioeliminable surfactant is required for biological or medical applications.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0942-0940
    Keywords: Colloid cyst ; neurenteric cyst ; Rathke's cleft cyst ; suprasellar cyst
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two cases of entirely suprasellar cysts are reported. Total surgical removal was performed in both cases. Pathological and immunohistochemical profiles were consistent with neurenteric cysts, Rathke's cleft cysts or colloid cysts and was also in keeping with an endodermal origin. It is now admitted that these three kinds of cysts share similar histological and immunohistological features. We propose an hypothesis of common embryological origin from endodermal remnants.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-1536
    Keywords: Key words Microgel particles ; Interpenetrating networks ; Copolymer latex particles ; Latex 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  A comparison of the swelling behaviour of two types of hydrogel particles, namely, random poly[(acrylic acid)-co-(acrylamide)] [P(AAc-co-AAm)] particles and PAAc/PAAm interpenetrating network (IPN) particles, has been made using temperature and pH as the triggers. Both types of particles were synthesised by inverse microemulsion polymerisation. The conversion yield of AAc was found to be around 60 wt% due to the partition of this monomer between the aqueous and organic phases. The AAc content was thus lower in the final particles than in the initial composition. Both types of hydrogel particle exhibit an upper critical solution temperature associated with the breakage of the polymer–polymer hydrogen bonds. The maximum swelling ratio occurred in both cases at approximately equimolar AAc and AAm content of the particles. A sharper swelling transition was observed for the PAAc/PAAm IPN particles. This is because of the co-operative nature of the interactions between the PAAc and PAAm chains, the so-called “zipper effect”. A very much higher swelling ratio was obtained using pH as the trigger compared to using temperature. This difference in behaviour is related to the relative strengths of the forces involved in the particle swelling. Electrostatic repulsion forces, associated with the AAc dissociation with increasing pH, are much stronger than the hydrogen bonds.
    Type of Medium: Electronic Resource
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