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  • 1
    ISSN: 1435-1536
    Keywords: Polymeremulsion ; polymermicrosphere ; XPSanalysis ; styrene ; 2-hydroxyethylmethacrylate
    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 Polymer microspheres composed of various compositions of styrene and 2-hydroxyethyl methacrylate (HEMA) were produced by batch emulsifier-free emulsion polymerization. The HEMA content at the surface, [HEMA] s , of the microspheres powdered by freeze-drying was determined by both quantitativeC 1s /O 1s analysis andC 1s peak shape analysis of the x-ray photoelectron spectroscopic spectra. When the HEMA content in the microsphere, [HEMA] p , was less than about 5 mole%, the [HEMA] s values determined by the two different methods showed good agreement. At [HEMA]p above 5 mole %, [HEMA]s values determined by the first method were about 15 mole % greater than those determined by the second. They both showed a similar tendency with the [HEMA] s being higher than the [HEMA] p , e.g., when [HEMA] p was 1 mole %, [HEMA] s was 11 mole %. The intensity of the satellite peak due to theπ→π * transition of the benzene ring of the styrene component decreased with an increase in [HEMA] p , to zero at 5 mole % of [HEMA] p . These results indicate that the HEMA component is localized at the surface.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 269 (1991), S. 1126-1132 
    ISSN: 1435-1536
    Keywords: Polymeremulsion ; microsphere ; vinylgroup ; brominetitration ; dispersionpolymerization ; seededpolymerization
    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 distribution of vinyl groups in polystyrene/poly(styrene-divinylbenzene) (PS/P(S-DVB)) composite microspheres produced by seeded copolymerization of S and DVB in the presence of 2.1-μm monodisperse PS seed particles was estimated from the amount detected with bromine titration method as a function of the reaction time under various conditions.
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  • 3
    ISSN: 1435-1536
    Keywords: Polymeremulsion ; polymermicrosphhere ; bovineserumalbumin ; proteinadsurption ; surfacehydrophilicity ; surfaceheterogeneity
    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 adsorption behaviors of bovine serum albumin (BSA) containing both dimeric and monomeric species onto polymer microspheres were examined using various homopolymers and poly(2-hydroxyethyl methacrylate)/polystyrene composite microspheres which were produced by the emulsifier-free (seeded) emulsion polymerization technique. The preferential adsorption of the BSA dimer was clearly observed in an optimum region of the surface hydrophilicities of the polymer microspheres. The preferential adsorption of the BSA dimer onto the composite polymer microspheres having heterogeneous surfaces consisting of hydrophilic and hydrophobic parts was more marked than those onto the homopolymer and copolymer microspheres having homogeneous surfaces.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 270 (1992), S. 733-737 
    ISSN: 1435-1536
    Keywords: Polymeremulsion ; microsphere ; chloromethylgroup ; polyamine ; cationicgroup ; dispersionpolymerization ; seededpolymerization
    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 Micron-size monodisperse crosslinked polymer microspheres having chloromethyl groups were prepared by seeded copolymerization of styrene, divinylbenzene, and chloromethylstyrene in the presence of 2.1-μ monodisperse polystyrene seed particles produced by dispersion polymerization. The modification reaction of chloromethyl groups on the surfaces with polyamines such as triethylenetetramine and ethylenediamine was carried out. From the measurements of ξ potential and the amount of chloride ion released, the introduction of a large number of cationic groups at the surfaces was confirmed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 19 (1981), S. 302-310 
    ISSN: 1741-0444
    Keywords: Electrical properties of skin ; Skin impedance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract This paper describes the non-linear electrical properties of the skin during the passage of a sinusoidal current from the standpoint of the constant-current method. The non-linearity occurs in the current dependency of the skin impedance and in Lissajous figures. It exhibits both rapid and slow variations. The concept of a non-linear impedance and its equivalent circuit are introduced for a sinusoidal voltage. With regard to the current dependency of the impedance it can be said that both the starting point and the degree of the dependency vary with frequency and impedance. The nonlinearity is more apparent with a larger current, a lower frequency, and a higher impedance. with an increasing current, the ionic conductance increases and the polarisation admittance decreases. Lissajous figures are formed when the voltage is distorted notably from the sinusoidal wave form. Detailed investigations are undertaken for the elliptic figures, third harmonics, rectification, and breakdown of the skin appearing with a decrease of the frequency and increase of the current. Finally, the special mechanism of the ionic conduction in the keratin layer is indicated as one of the causes for non-linearity.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 17 (1979), S. 135-137 
    ISSN: 1741-0444
    Keywords: Impedance measurement ; Skin impedance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 30 (1992), S. 562-564 
    ISSN: 1741-0444
    Keywords: Control instrument for drowsines ; Galvanic skin reflex ; Skin impedance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 16 (1978), S. 592-594 
    ISSN: 1741-0444
    Keywords: Dispersion of skin impedance ; Skin impedance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 16 (1978), S. 623-632 
    ISSN: 1741-0444
    Keywords: Performance evaluation of drugs and cosmetics ; Skin impedance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire De nombreuses études ont déjà été effectuées sur les applications de la mesure de l'impédance aux variations de paramètres biologiques. La base de ces mesures est la différence due au facteur objectif entre l'impédance de référence (qui ne contient pas de facteur objectif) et l'impédance qui le contient. Dans le passé, les efforts ont surtout porté sur la relation entre le changement d'impédance de la peau et les facteurs objectifs tels que des maladies, et seules quelques études ont porté sur ce principe de mesure pour établir une impédance de référence en vue d'une méthode d'analyse de données. L'article propose: (a) une méthode pour la détermination d'un niveau de référence basée sur la transformation d'identité de l'impédance de la peau, (b) une théorie de transformation linéaire pour l'analyse des données et (c) le triangle exprimant le taux de changement des résultats obtenus, et il établit un principe de base des mesures. L'évaluation de performances de cosmétiques a été effectuée pour donner un exemple d'application du principe.
    Abstract: Zusammenfassung In den letzten Jahren wurden zahlreiche Untersuchungen der Anwendung von Hauptimpedanz auf biologische Messungen durchgeführt. Die Basis für dieses Veifahren ist, daß zwischen einer Referenzimpedanz und der Impedanz ein Unterschied entsteht. In der Vergangenheit wurde die Wichigkeit der Relation zwischen einer Veränderung in der Hautimpedanz und den objektiven Faktoren, wie Z.B. Krankheiten, betont, und es gibt nur wenige Studien über das Meßprinzip, die Bestimmung der Referenzimpedanz und Datenauswertungsmethode. (a) Eine Methode zur Festlegung eines auf der Identitätstransformation der Hautimpedanz basierenden Referenzniveaus, (b) lineare Transformationstheorie zur Datenanalyse und (c) ein Grundprinzip zum Messen wurden erarbeitet. Als Anwendungsbeispiel dieses Prinzips wurde eine Leistungsbewertung für Kosmetika durchgeführt.
    Notes: Abstract Numerous studies have been carried out on the application of skin impedance to biological measurement. Measurement is possible because a difference will result due to the objective factor of the impedance, and the reference impedance (which does contain the objective factor). Emphasis has been placed, in the past, on the relationship between the change in skin impedance and objective factors such as disease, and there are only a few studies on the principle of measurement as the establishment of a reference impedance and a data-analysis method. (a) A method for setting a reference level based on identity transformation of skin impedance, (b) linear-transformation theory for data analysis, and (c) rate of change triangle expression of the results obtained, are proposed, and a basic principle of measurement has been established. Performance evaluation of cosmetics was carried out as an example of the application of this principle.
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