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  • Articles: DFG German National Licenses  (5)
  • amino acids  (3)
  • Acidity  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 12 (1992), S. 201-211 
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 18 (1993), S. 183-192 
    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
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  • 3
    ISSN: 1573-9058
    Keywords: amino acids ; chlorophyll ; 14CO2- and 14C-sucrose incorporation ; organic acids ; primary photosynthetic metabolites ; stem ; stomatal conductance ; sugars ; transpiration rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in growth parameters and 14CO2 and [U-14C]-sucrose incorporation into the primary metabolic pools and essential oil were investigated in leaves and stems of M. spicata treated with etherel and gibberellic acid (GA). Compared to the control, GA and etherel treatments induced significant phenotypic changes and a decrease in chlorophyll content, CO2 exchange rate, and stomatal conductance. Treatment with etherel led to increased total incorporation of 14CO2 into the leaves wheras total incorporation from 14C sucrose was decreased. When 14CO2 was fed, the incorporation into the ethanol soluble fraction, sugars, organic acids, and essential oil was significantly higher in etherel treated leaves than in the control. However, [U-14C]-sucrose feeding led to decreased label incorporation in the ethanol-soluble fraction, sugars, organic acids, and essential oils compared to the control. When 14CO2 was fed to GA treated leaves, label incorporation in ethanol-insoluble fraction, sugars, and oils was significantly higher than in the control. In contrast, when [U-14C]-sucrose was fed the incorporation in the ethanol soluble fraction, sugars, organic acids, and oil was significantly lower than in the control. Hence the hormone treatment induces a differential utilization of precursors for oil biosynthesis and accumulation and differences in partitioning of label between leaf and stem. Etherel and GA influence the partitioning of primary photosynthetic metabolites and thus modify plant growth and essential oil accumulation.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Photosynthetica 35 (1998), S. 391-398 
    ISSN: 1573-9058
    Keywords: acetate ; amino acids ; 14CO2 ; Cymbopogon winterianus ; oil ; organic acids ; primary and secondary metabolites ; sugars ; [U-14C] ; [U-14C] saccharose incorporation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in the utilization pattern of primary substrate, viz. [U-14C] acetate, 14CO2 and [U-14C] saccharose, and the contents of 14C fixation products in photosynthetic metabolites (sugars, amino acids, and organic acids) were determined in Fe-deficient citronella in relation to the essential oil accumulation. There was an overall decrease in photosynthetic efficiency of the Fe-deficient plants as evidenced by lower levels of incorporation into the sugar fraction and essential oil after 14CO2 had been supplied. When acetate and saccharose were fed to the Fe-deficient plants, despite a higher incorporation of label into sugars, amino acids, and organic acids, there was a lower incorporation of these metabolites into essential oils than in control plants. Thus, the availability of precursors and the translocation to a site of synthesis/accumulation, severely affected by Fe deficiency, is equally important for the essential oil biosynthesis in citronella.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-9058
    Keywords: amino acids ; biomass ; chlorophyll ; 14CO2 and [U-14C] sucrose incorporation ; essential oils ; leaf development ; organic acids ; primary photosynthates ; sugars ; Zn-stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in growth, CO2 exchange rate, and distribution of photosynthetically fixed 14CO2 into the primary photosynthetic metabolic pool (sugars, amino acids and organic acids) and essential oil accumulation were determined in leaves (leaf positions 1-6 from apex) of developing peppermint grown in a solution culture at Zn concentrations of 0 and 0.05 g m-3. There was a significant decrease in 14C incorporation in total, ethanol-soluble and ethanol-insoluble fractions in Zn deficient plants at all leaf positions. 14C incorporated in essential oil and in sugars were significantly higher in leaf pairs 1 to 3 than in leaf pairs 4 to 6. 14C incorporation into amino acids and organic acids was higher in all leaf pairs in Zn deficient plants. Statistical analysis showed a positive significant association between Zn content of leaf and 14C incorporation into ethanol-soluble fraction and sugars and a negative correlation with 14C incorporation into amino acids and organic acids. Hence the content of sugars in leaves significantly influences essential oil accumulation under Zn stress.
    Type of Medium: Electronic Resource
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