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  • 1
    Electronic Resource
    Electronic Resource
    Microcalorimetric studies of zeolite acidity (1992)
    Springer
    Catalysis letters 12 (1992), S. 201-211 
    Details
    ISSN: 1572-879X
    Keywords: Acidity ; gravimetry ; heat of adsorption ; H-Mordenite ; H-Y ; H-ZSM-5 ; microcalorimetry ; pyridine ; zeolite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The acidity characteristics of H-ZSM-5, H-Mordenite and H-Y zeolite have been studied by microcalorimetric and gravimetric measurements of pyridine adsorption. H-ZSM-5 and H-Mordenite have Brønsted acid sites of primarily homogenous strength, with H-Mordenite having the stronger sites, whereas H-Y zeolite had Brønsted sites of varying strength. The effects of Na exchange level in H-Y zeolite and high temperature calcination for H-Mordenite have also been examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00767202
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  • 2
    Electronic Resource
    Electronic Resource
    Thermogravimetric and microcalorimetric studies of ZSM-5 acidity (1993)
    Springer
    Catalysis letters 18 (1993), S. 183-192 
    Details
    ISSN: 1572-879X
    Keywords: Acidity ; zeolites ; microcalorimetry ; thermogravimetry ; pyridine adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The combination of thermogravimetry, microcalorimetry and infrared spectroscopy studies of pyridine adsorption has been used to characterize the acidity of a ZSM-5 catalyst. The majority of the acid sites are Brønsted acid centers associated with framework Al species, with heats of pyridine adsorption equal to 140 kJ/mol. Non-framework Al species in the zeolite sample of this study eliminate an approximately equal number of Brønsted acid sites. These nonframework Al species also produce strong Lewis acid sites with pyridine adsorption heats greater than 140 kJ/mol, as well as weak adsorption sites (e.g., weak Bransted acid sites or hydrogen bonding sites) with heats equal to 90–140 kJ/mol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00769437
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of liming and carbofuran on groundnut yield in sandy soils in Niger (1992)
    Springer
    Nutrient cycling in agroecosystems 33 (1992), S. 203-208 
    Details
    ISSN: 1573-0867
    Keywords: Al ; Arachis hypogaea ; carbofuran ; lime ; nematodes ; pH ; yields
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract One of the constraints to groundnut production in sandy soils of Niger is crop growth variability. In early 1989, a trial on the effect of lime and carbofuran on soil pH, Al toxicity, nematode population and groundnut yield was initiated to study crop growth variability. Groundnut was sown in the 1989 rainy season, followed by pearl millet (Pennisatum glaucum) in the 1989–90 dry season and again groundnut in the 1990–91 rainy, and dry seasons. In 1989 the carbofuran treatment increased the pod yield. Lime application did not change the pH and exchangeable Al+++ contents in the soil and did not increase groundnut yield. In the 1990–91 rainy and dry season, however, the application of 10 t ha−1 of lime increased pH, decreased exchangeable Al+++, improved crop growth and increased the yield of groundnut to the same level as was achieved by the carbofuran treatment. Application of lime did not affect the nematode population, which were reduced by the carbofuran.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01050875
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  • 4
    Electronic Resource
    Electronic Resource
    Role of Scutellonema clathricaudatum in etiology of groundnut growth variability in Niger (1992)
    Springer
    Plant and soil 143 (1992), S. 133-139 
    Details
    ISSN: 1573-5036
    Keywords: aluminium toxicity ; Arachis hypogaea ; crop growth variability ; groundnut ; peanut ; pesticide ; plant-parasitic nematodes ; Niger ; Sahel ; Scutellonema clathricaudatum ; soil pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Variation in crop growth is an important limiting factor for groundnut production in Niger. Populations of Aphelenchoides sp., Ditylenchus sp., Helicotylenchus sp., Hoplolaimus pararobustus, Macroposthonia curvata, Paralongidorus bullatus, Scutellonema clathricaudatum, Telotylenchus indicus and Xiphinema parasetariae have been associated with groundnut crop growth variability. S. clathricaudatum, X. parasetariae and T. indicus were widespread and S. clathricaudatum was most abundant nematode. Population densities of S. clathricaudatum was always higher in the roots of poorly growing, chlorotic and stunted plants than in the roots of apparently healthy plants. A preplant population density of 1.3 S. clathricaudatum cm-3 soil caused (p=0.05) reduction in plant growth of groundnut cv. 55–437. S. clathricaudatum was mainly confined to 0–15 cm soil depth at the time of planting in June and was not found below 45 cm depth at any time during the crop growth period. Soil application of carbofuran (10 kg a.i ha-1) reduced the nematode population densities and resulted in vigorous and uniform crop growth. Higher Al and H-ion concentrations (0.50 meq 100 g-1 soil) also was associated with poorly growing chlorotic seedlings. Symptoms of nematode-caused variable growth were evident 3 to 4 weeks after seedling emergence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00009138
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