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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Thermochimica Acta 21 (1977), S. 59-88 
    ISSN: 0040-6031
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 2 (1994), S. 239-244 
    ISSN: 1573-4846
    Keywords: thermoporometry ; permeability ; texture of gels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The textures of silica gels made by two-step acid/base and acid/acid catalysis of TEOS have been examined by thermoporometry (TPM) and NMR, and their permeabilities (D) have been measured by a thermal expansion technique. Using the pore size distribution given by TPM, which includes a large proportion of macropores (≥30 nm), calculated values of D are seriously overestimated. We conclude that, consistent with a theoretical prediction, compliant materials such as gels undergo contraction during freezing in the calorimeter, so that most of the macropore volume reported by TPM is actually extracted from mesopores. The mesopore radius reported by TPM is underestimated by only ∼20%, even if 50% of the pore liquid is drained during crystallization, assuming that the change in pore radius is related to the cube root of the volume change. NMR does not distinguish macropores, because of diffusional averaging, but provides an apparent distribution that permits an accurate estimate of the permeability.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 2 (1994), S. 277-281 
    ISSN: 1573-4846
    Keywords: thermoporometry ; densification of aerogels ; PDA: Partially densified aerogels ; impregnation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The evolution of the texture of silica aerogels during sintering is studied by thermoporometry for both neutral and base catalysed materials. During the densification the macroporous volume drops and the analysis of the mesopore size distribution evolution shows that the collapse of the smallest mesopores is responsible for the macropore volume transformation. However, corrections of the measured volumes are necessary to characterize the most compliant materials.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 7 (1996), S. 45-51 
    ISSN: 1573-4846
    Keywords: sol-gel ; immunoassays ; porosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Parasites have been encapsulated within sol-gel silica matrices. Thermoporometry measurements show that the pore size depends strongly on experimental conditions. Pores as large as 100 Å in diameter can be obtained, allowing the diffusion of large biomolecules such as immunoglobulins. TEM observations, performed on procaryote (bacteria) and eucaryote (protozoa) specimen show that the cellular organization and the integrity of the plasma membrane of entrapped parasites are preserved. Moreover they retain their antigenic activity and can react specifically with the corresponding antibodies. Sol-gel matrices have then been used for the realization of enzyme-linked immunosorbent assays (ELISA) directly with the sera of infected patients. Two examples are described, one with parasitic protozoa, Leishmania, and the other one with the cystic hydatid stage of tapeworm parasites, Echinococcus granulosus.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 2 (1994), S. 363-366 
    ISSN: 1573-4846
    Keywords: silica-alumina ; hydrogel ; microwave drying ; convective drying ; texture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The porous texture of silica-alumina hydrogel can be taylored by controlling the operating parameters of the preparation process. As the drying drastically modifies the texture it is important to minimize pore volume and radius decreases. Owing to a low drying temperature microwave heating coupled with convective drying could be a way to preserve the hydrogel texture. Its effects have been studied and it appears that the characteristics of the air flow are the main parameters of this drying mode which does not present decisive advantages as compared with other drying modes.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 8 (1997), S. 189-194 
    ISSN: 1573-4846
    Keywords: texture ; silica gels ; silica-alumina gels ; catalyst
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The porous texture of silica and silica-alumina hydrogels has been studied by means of thermoporometry measurements. The texture of the xerogels resulting from spray-drying of silica-alumina hydrogels is then evaluated by different methods: BET, Hg-porosimetry and thermoporometry. As each method is based on different physical principles and assumptions, differences are observed between the results. However, these results are complementary and their comparison leads to a better knowledge of the texture of the catalyst particles. A good agreement is observed between thermoporometry and nitrogen adsorption-desorption measurements, whereas mercury porosimetry results are very different. Silica-alumina gels appear as mainly mesoporous materials.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 4 (1985), S. 1089-1091 
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 28 (1983), S. 87-93 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine thermische Methode ermöglicht die Oberflächenspannungγ/s einer Substanz mit der Erniedrigung der Tripelpunkttemperatur in Bezug zu bringen. Eine vorangehende Bestimmung der Dicke der Kondensatschicht, deren Aggregatzustand sich bei Kontakt mit dem porösen Material nicht ändert, ist überflüssig. Die Methode wird auf einige organische Verbindungen und ein Metall (Indium) angewandt.
    Abstract: Резюме Описаны практически е процессы термическ ого метода, связывающего поверхностное натяжение γтв.,ж. веще ства на границе разде ла твердое тело — жидкость. Преды дущее определение толщины слоя конденсата, не за мерзающего около стенок пористо го материала, не являетс я более необходимым. У казанный процесс применим к ор ганическим веществам и к металлу индию.
    Notes: Abstract A thermal method connects the solid-liquid surface tensionγ/s of a substance to its triple point temperature depression. Here a practical process for application of this method is described. A previous determination of the thickness of the condensate layer which does not freeze near the wall of the porous material is no longer necessary. The process is applied to some organic substances and to a metal (indium).
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 20 (1981), S. 389-400 
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé L'analyse par diffractionX a montré que le soufre retenu dans une matrice mésoporeuse se trouve essentiellement sous la forme orthorhombique α et conserve cette structure cristalline jusqu'à la fusion. L'analyse calorimétrique a confirmé pour ce métalloÏde les résultats théoriques régissant le changement d'état liquide ⇄ solide et a permis d'en déterminer les paramètres: entropie de fusion et énergie interfaciale liquide-solideγ ls. Cette étude thermodynamique a montré en outre qu'il était possible de prévoir dans le cas d'un soufre divisé par condensation dans un milieu poreux, une modification du domaine de stabilité des formes allotropiques.
    Abstract: Zusammenfassung Die Röntgenanalyse von in halbdurchlÄssigem Material gehaltenem Schwefel zeigt im Wesentlichen eine orthorhombische Kristallstruktur. Diese Form erfÄhrt keinen Phasenübergang vor dem Schmelzen. Die kalorimetrische Analyse eines so verteilten Schwefels erhÄrtete die theoretischen Ergebnisse, welche in einem vorangegangenen Artikel für Flüssigfest-Umwandlungen im Inneren eines porösen Materials dargelegt worden sind. Ausserdem ermöglicht diese Analyse die Schmelz-Entropie und die Festflüssig-OberflÄchenspannungγ ls des Schwefels zu bestimmen. Eine thermodynamische Studie gestattet auch die Voraussage zum StabilitÄtsbereich derα undΒ allotropischen Formen von verteiltem Schwefel.
    Notes: Abstract The X-ray analysis of sulphur held in a mesoporous material reveals essentially an orthorhombic crystalline structure. This form does not undergo phase transition before melting. The calorimetric analysis of such a divided sulphur corroborates the theoretical results which were established for liquid ⇄ solid transformation inside a porous material in a previous paper. Moreover, this analysis helps determine its melting entropy and the solid-liquid surface tensionγ ls of sulphur. A thermodynamic study also permits a predetermination of the stability range ofα andΒ allotropic forms in the case of divided sulphur.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 31 (1996), S. 5179-5184 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract ZrO2 coatings were obtained by the alkoxide route and deposited on to stainless steel using the dip-coating technique. The starting solutions were prepared by mixing zirconium tetrabutoxide, isopropanol, acetylacetone. The water content for the hydrolytic reaction came from atmospheric moisture. These coatings were characterized by scanning electron microscopy, X-ray fluorescence, Fourier transform-infrared spectroscopy, and X-ray diffraction. Their deformation capability was studied by using the stretch deformation test. It is worth noting that these coatings deposited on stainless steel have the capacity to deform extensively without apparent cracks or fracture. Their ability to protect the metallic substrate against corrosion, in a neutral chloride medium, was investigated. For this purpose, the pitting potential of the coated metal was measured by the potentiodynamic polarization technique and the a.c. impedance diagram of the coating was recorded in the potentiostatic mode at the rest potential. The variation in the pitting potentials revealed a temporary increase in the corrosion resistance of coated stainless steel, which disappeared after ageing of the coatings in the chloride solution. During ageing, the coating resistance deduced from the complex diagram via an equivalent circuit, decreases, thus showing a deterioration.
    Type of Medium: Electronic Resource
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