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  • Burkard sporetrap  (2)
  • surface area  (2)
  • Springer  (4)
  • Molecular Diversity Preservation International
  • PANGAEA
  • 1995-1999  (4)
Collection
Keywords
Publisher
  • Springer  (4)
  • Molecular Diversity Preservation International
  • PANGAEA
Years
  • 1995-1999  (4)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Determination of the Glass Transition Temperatures of Some New Methyl Methacrylate Copolymers Using Modulated Temperature Differential Scanning Calorimetry (MTDSC) (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 1464-1469 
    Details
    ISSN: 1573-904X
    Keywords: dynamic differential scanning calorimetry ; thermogravimetric analysis ; methyl methacrylate ; surface area ; graft copolymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The purpose of this study was to determine the glass transition temperatures of new graft copolymers using Modulated Temperature Differential Scanning Calorimetry (MTDSC), and to assess the differences between starch and cellulosic derivatives of methyl methacrylate and between two different drying methods used in their preparation. Methods. Graft copolymers of methyl methacrylate were synthesized and dried by oven or freeze-drying. Surface area measurements and different thermal analysis techniques (Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA) and MTDSC) were used to characterize these copolymers. Results. DSC was not sensitive enough to identify the Tgs of the copolymers, however they were clearly identifiable by MTDSC. Tg values obtained may depend on the method of preparation that also altered their physical characteristics e.g. specific surface area. Cellulose derivatives showed lower Tgs than starch derivatives. The results also depended on the drying method used, thus, freeze dried products had slightly lower Tgs than oven dried products. Conclusions. MTDSC represents a useful thermal technique that allows the identification of glass transitions in these new copolymers with higher sensitivity and resolution than conventional DSC, separating the transition from overlapping phenomena such as decomposition or dehydration. The Tg of this new class of copolymers appeared to be dependent on polymer composition and drying method used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018971630036
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Sampling in aerobiology. Differences between traverses along the length of the slide in Hirst sporetraps (1996)
    Springer
    Aerobiologia 12 (1996), S. 161-166 
    Details
    ISSN: 1573-3025
    Keywords: Aerobiology ; Methodology ; Sampling error ; Burkard sporetrap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two years of data from four longitudinal traverses along each day's slide prepared from a continuously running Burkard sporetrap have been analyzed statistically. Using the Friedman test, a statistically significant difference was found between the four traverses, with a greater than 7% loss of pollen grains in the two outer traverses in relation to the inner. Four slides were then selected for more detailed analysis, using 18 longitudinal traverses with a 1-mm separation from the upper to the lower edge of the Melinex tape. There was found to be a progressive decline from the centre to the outside, and more than 4% of pollen grains were found outside the typical 14 mm width of the impaction orifice. There was no correlation between pollen grain size and the decline in counts from the centre to the outside. For the complete data set, there was a general rise in the diversity of bollen types with increasing sample counts, but above about 1000 pollen grains per sample there were no more than 27 pollen types found, often even fewer. A discussion is presented of whether four traverses really should be a fixing sample size, or whether it might be better to fix the total pollen count beginning with a traverse in the middle of the slide and ending with a variable number of traverses when that count is reached.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02447407
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  • 3
    Electronic Resource
    Electronic Resource
    Sampling in aerobiology. Differences between traverses along the length of the slide in Hirst sporetraps (1996)
    Springer
    Aerobiologia 12 (1996), S. 161-166 
    Details
    ISSN: 1573-3025
    Keywords: Aerobiology ; Methodology ; Sampling error ; Burkard sporetrap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two years of data from four longitudinal traverses along each day's slide prepared from a continuously running Burkard sporetrap have been analyzed statistically. Using the Friedman test, a statistically significant difference was found between the four traverses, with a greater than 7% loss of pollen grains in the two outer traverses in relation to the inner. Four slides were then selected for more detailed analysis, using 18 longitudinal traverses with a 1-mm separation from the upper to the lower edge of the Melinex tape. There was found to be a progressive decline from the centre to the outside, and more than 4% of pollen grains were found outside the typical 14 mm width of the impaction orifice. There was no correlation between pollen grain size and the decline in counts from the centre to the outside. For the complete data set, there was a general rise in the diversity of pollen types with increasing sample counts, but above about 1000 pollen grains per sample there were no more than 27 pollen types found, often even fewer. A discussion is presented of whether four traverses really should be a fixing sample size, or whether it might be better to fix the total pollen count beginning with a traverse in the middle of the slide and ending with a variable number of traverses when that count is reached.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02248144
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  • 4
    Electronic Resource
    Electronic Resource
    Study of the Porous Solids Obtained by Acid Treatment of a High Surface Area Saponite (1999)
    Springer
    Journal of porous materials 6 (1999), S. 335-344 
    Details
    ISSN: 1573-4854
    Keywords: saponite ; acid treatment ; surface area ; porosity ; acid centres
    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 new deposit of saponite, Vicálvaro (Madrid, Spain), has recently been described in the Madrid Basin (provinces of Madrid and Toledo, Central Spain). The acid treatment of such material and the characterization of the solids obtained are reported in the present paper. The surface area of the natural saponite is rather high, 197 m2/g, related to the very small size of the clay particles due to the sedimentary origin of the deposit. The treatment of the saponitic material at room temperature with 0.62 wt% HCl for times of between 2 and 48 h or with 1.25 wt% HCl solutions for times of up to 6 h produces a partial dissolution of the saponite structure, resulting in the formation of mixtures of unattacked saponite and free silica, with a high development of the textural properties of the solids. The treatment with 1.25 wt% HCl solutions for times of over 6 h results in an almost total dissolution of the structure of the clay, the obtained solids being mainly formed by some delaminated saponite sheets, free silica and insoluble impurities. Solids with a maximum surface area of 462 m2/g and a maximum number of acid centres of 0.98 mmol H+/g are obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009657312123
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