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  • 1
    Electronic Resource
    Electronic Resource
    Dissolved organic matter and its parent organic matter in grass upland soil horizons studied by analytical pyrolysis techniques (1998)
    Oxford, UK : Blackwell Science, Ltd
    European journal of soil science 49 (1998), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: We have sought to understand the molecular mechanisms by which dissolved organic matter (DOM) forms and soil organic matter (SOM) degrades in upland peaty gley soil under grass. Pyrolysis mass spectrometry (Py-MS) and pyrolysis gas chromatography mass spectrometry (Py-GC/MS) were applied to characterize the DOM collected from lysimeters and its parent SOM. The macromolecular organic matter in the litter and fermentation (Lf) horizon of the soil consists primarily of little decomposed lignocellulose from grass, whereas the humus (Oh) horizon is characterized by an accumulation of selectively decomposed lignocellulose material, microbial metabolites and bound fatty acids. The mineral horizon produced a relative enrichment of furan structures derived from microbial reworking of plant polysaccharides but virtually no lignin signals. A series of exceptional long chain C43 to C53 fatty acids with odd over even predominance, probably derived from mycobacteria, were also identified in the Oh horizon. Side-chain oxidation and shortening, increase of carboxyl functionality and selective removal of syringyl (S) 〉 guaiacyl (G) 〉 p-hydroxyphenyl (P) lignin units were the main reactions when lignin degraded. Compared with SOM, the DOM shows a large accumulation of more oxidized lignin and aromatic structures, especially those containing carboxylic and dicarboxylic acid functionalities and with shorter side-chain length. The polysaccharide-type compounds in the DOM were more modified (greater abundance of furan structures in pyrolysis products), and had significantly lower molecular weight and more diverse polymeric structures than did those in soils. Increased temperature and rainfall appeared to result in greater relative abundance of lignin degradation products and aromatic compounds in DOM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1998.00141.x
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  • 2
    Electronic Resource
    Electronic Resource
    Solvent-free and splitless injection method for open tubular columns (1977)
    s.l. : American Chemical Society
    Analytical chemistry 49 (1977), S. 1881-1884 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac50020a067
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  • 3
    Electronic Resource
    Electronic Resource
    Chemical differences between wildtype and gibberellin mutants of tomato determined by pyrolysis-mass spectrometry (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 16 (1993), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Leaf, stem and root material of wild-type and gibberellin (GA)-deficient mutants of tomato (Lycopersicum esculentum L.) were analysed by pyrolysis-mass spectrometry for possible differentiation in chemical allocation pattern among cell wall and cytoplasm. GA-deficiency is accompanied by changes in the relative growth rate (RGR). RGR-correlated changes were found in leaves in the comparative amounts of cellulose- and protein-derived fragments. The low-RGR genotypes contained more protein and nucleic acid, the high-RGR ones more cellulose. In root material, a higher contribution of cellulose, hemicellulose and G- and S-lignin was found for the lower-RGR plants and comparatively high protein in the high-RGR genotypes. For stems, less clear results were obtained, possibly because of variation in the ratio of syringyl- and guaiacyl-lignin. Part of the results might be explained by a GA-dependent change in cell size.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1996.tb02063.x
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  • 4
    Electronic Resource
    Electronic Resource
    Relative growth rate correlates negatively with pathogen resistance in radish: the role of plant chemistry (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 19 (1996), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Plant growth rate has frequently been associated with herbivore defence: a large investment in quantitative defence compounds occurs at the expense of growth. We tested whether such a relationship also holds for growth rate and pathogen resistance. For 15 radish (Raphanus sativus L.) cultivars, we determined the potential growth rate and the resistance to fungal wilt disease caused by Fusarium oxysporum. We subsequently aimed to explain a putative negative relationship between growth rate and resistance based on plant chemical composition. Both growth rate and resistance level varied greatly among cultivars. Moreover, there was a strong negative correlation between growth rate and resistance, i.e. there are costs associated with a high resistance level. Roots of slow-growing, resistant cultivars have a higher biomass density. Using pyrolysis mass spectrometry. we part1y explained variation in both growth rate and resistance in terms of the same change in chemical composition. Leaves of slow-growing, resistant cultivars contained more cell wall material. Surprisingly, roots of slow-growing, highly resistant cultivars contained significantly less cell wall material, and more cytoplasmic elements (proteins). We speculate that this higher protein concentration is related to high construction and turn-over costs and high metabolic activity. The latter in turn is thought to be responsible for a rapid and adequate resistance reaction, in which phenols may be involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1996.tb00006.x
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of nitrogen supply on the anatomy and chemical composition of leaves of four grass species belonging to the genus Poa, as determined by image-processing analysis and pyrolysis–mass spectrometry (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 20 (1997), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Previous experiments have shown that the anatomy and chemical composition of leaves of inherently fast- and slow-growing grass species, grown at non-limiting nitrogen supply, differ systematically. The present experiment was carried out to investigate whether these differences persist when the plants are grown at an intermediate or a very low nitrogen supply. To this end, the inherently fast-growing Poa annua L. and Poa trivialis L., and the inherently slow-growing Poa compressa L. and Poa pratensis (L.) Schreb. were grown hydroponically at three levels of nitrate supply: at optimum (RGRmax) and at relative addition rates of 100 and 50 mmol N (mol N)−1 d−1 (RAR100 and RAR50), respectively.As expected, at the lowest N supply, the potentially fast-growing species grew at the same rate as the inherently slow-growing ones. Similarly, the differences in leaf area ratio (LAR, leaf area:total dry mass), specific leaf area (SLA, leaf arear:leaf dry mass) and leaf mass ratio (LMR, leaf dry mass:total dry mass) disappeared. Under optimal conditions, the fast-growing species differed from the slow-growing ones in that they had a higher N concentration. There were no significant differences in C concentration. With decreasing N supply, the total N concentration decreased and the differences between the species disappeared. The total C concentration increased for the fast-growing species and decreased for the slow-growing ones, i.e. the small, but insignificant, difference in C concentration between the species at RGRmax increased with decreasing N supply.The chemical composition of the leaves at low N supply, analysed in more detail by pyrolysis–mass spectrometry, showed an increase in the relative amounts of guaiacyl lignin, cellulose and hemicellulose, whereas those of syringyl lignin and protein decreased.The anatomy and morphology of the leaves of the four grass species differing in RGRmax were analysed by image-processing analysis. The proportion of the total volume occupied by mesophyll plus intercellular spaces and epidermis did not correlate with the amount of leaf mass per unit leaf area (specific leaf mass, SLM) at different N supply. The higher SLM at low N supply was caused partly by a high proportion of non-veinal sclerenchymatic cells per cross-section and partly by the smaller volume of epidermal cells.We conclude that the decrease in relative growth rate (and increase in SLM) at decreasing N supply is partly due to chemical and anatomical changes. The differences between the fast- and slow-growing grass species at an optimum nutrient supply diminished when plants were growing at a limiting nitrogen supply.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1997.d01-135.x
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  • 6
    Electronic Resource
    Electronic Resource
    Changes in substituent distribution patterns during the conversion of cellulose toO-(2-hydroxyethyl) celluloses (1996)
    Springer
    Cellulose 3 (1996), S. 45-61 
    Details
    ISSN: 1572-882X
    Keywords: cellulose ; hydroxyethyl cellulose ; methylation analysis ; substituent distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Monomer compositional data of a series of hydroxyethyl celluloses (HECs) with molar substitutions (MS) ranging from 0.2 to 2.4 were used to analyse the substituents in the samples. The data reveal that the reactivity of the pendant hydroxyl groups in the substituents decreases in progressed states of derivatization, and that the reactivity of the 6-O-positions is only large compared to the 2-O-positions in non-derivatized glucosyl residues. These two processes are not taken into account in any of the statistical models for the description of the substituent distribution in HECs, which shows that the assumption that the relative reaction constants of the various hydroxyl groups in HECs remain constant throughout the whole reaction is false. The occurrence of maxima in the mole fractions of the monomers was examined as a function of the MS of the samples by principal component analysis of the monomer compositional data. The results show that in the beginning phase of the derivatization mainly monosubstituted monomers are formed and that chain propagation of these substituents takes place, whereas in the progressed states of conversion mainly di- and trisubstituted moieties are formed. The changes in the reactivity of the various hydroxyl groups during the conversion of cellulose to HECs can be described by a model wherein the interactions of both NaOH and the diluents with the cellulosics are taken into account.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02228790
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  • 7
    Electronic Resource
    Electronic Resource
    Environmental research for art conservation (ERA) (1997)
    Springer
    Journal of thermal analysis and calorimetry 49 (1997), S. 1571-1584 
    Details
    ISSN: 1572-8943
    Keywords: conservation ; environmental research for art
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The basic concept of this project is to identify and then use the changes which occur in the chemical and physical properties of traditional paint media both to indicate and integrate the effects of environmental conditions on paintings. To achieve this aim, test paint films are being prepared in accordance with traditional artists' recipes. Changes in material properties are monitored using a combination of non-invasive spectroscopy (Bacci), microsensors, thermoanalytical techniques (Odlyha), and microscale analytical mass spectrometry for molecular structure analysis (Boon). The test strips are calibrated by exposure to controlled environments (light, temperature, relative humidity and noxious gases) and alterations in their properties are quantified. This provides information on the nature and rate of change at the molecular level and a data base for evaluating the molecular monitoring strips after their exposure in the field. Field sites have been selected and include various locations in the Tate Gallery (UK), Sandham Chapel (Burghclere, UK), the Uffizi Gallery (It) and the Rijksmuseum (NL). Environmental conditions of some of these locations are being evaluated at present using the glass sensors described in project EV5VCT92 0144. Small piezoelectric quartz crystal humidity sensors will be installed to determine localised variations in relative humidity and temperature on [1] Stanley Spencer paintings in Sandham Chapel and [2] Giotto's “Madonna di Ognissanti” in the Uffizi Gallery. In addition novel coatings using picture varnishes are being applied to similar piezoelectric quartz crystal sensors to evaluate the effects of environmental impact on the chemistry of varnishes on paintings. Data are also being collected on the nature of chemical and physical changes in varnishes and paint media in actual paintings at the molecular level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01983717
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  • 8
    Electronic Resource
    Electronic Resource
    p-Coumaric acid — a monomer in the sporopollenin skeleton (1989)
    Springer
    Planta 179 (1989), S. 376-380 
    Details
    ISSN: 1432-2048
    Keywords: p-Coumaric acid ; Pinus (sporopollenin) ; Pollen ; Sporopollenin (natural, synthetic)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sporopollenin obtained from wings of Pinus mugo (Turra) pollen was analysed by pyrolysis mass spectrometry. In the spectrum, mass peaks which are characteristic for p-coumaric acid were dominant. p-Coumaric acid was the main degradation compound when the wing material was treated by a gentle method using AII3, and also when the remaining residue of the treated sporopollenin material was saponified. It is therefore assumed that p-coumaric acid is a genuine structural unit in the sporopollenin skeleton. In addition, the effects of AII3 treatment indicate that the p-coumaric acid might be bound by ether linkages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00391083
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  • 9
    Electronic Resource
    Electronic Resource
    p-coumaric acid — a monomer in the sporopollenin skeleton (1990)
    Springer
    Planta 181 (1990), S. 147-147 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00202338
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  • 10
    Electronic Resource
    Electronic Resource
    Localization of phytoalexin accumulation and determination of changes in lignin and carbohydrate composition in carnation (Dianthus caryophyllus L.) xylem as a consequence of infection with Fusarium oxysporum f. sp. dianthi, by pyrolysis-mass spectrometry (1990)
    Springer
    European journal of plant pathology 96 (1990), S. 133-153 
    Details
    ISSN: 1573-8469
    Keywords: cell walls ; guaiacyl lignin ; syringyl lignin ; dianthramides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Description / Table of Contents: Samenvatting Kleine stukjes xyleem en andere weefsels van de stengels van gezonde en geïnoculeerde planten van een tweetal anjercultivars, Novada en Lena, werden onderzocht op mate van lignificatie (lignine/polysaccharide verhouding) en ligninesamenstelling met behulp van pyrolyse-massaspectrometrie en pyrolyse-gaschromatografie massaspectrometrie. Deze techniek bleek ook bruikbaar voor het localiseren van fytoalexinen van het dianthramide-type, welke in anjer accumuleren na infectie metFusarium oxysporum f.sp.dianthi. De samenstelling van gezonde weefsels was bij beide cultivars praktisch gelijk. Bij de resistente cultivar Novada leidde infectie tot een verandering van guaiacyl-syringyllignine in guaiacyl-lignine in door gommen afgesloten delen van het xyleem. Xyleem met gommen bevatte aanzienlijke hoeveelheden van het fenolamide dianthalexine en van de andere fytoalexinen van het dianthramide type. De fytoalexinen werden niet aangetroffen in aangrenzend floeem, merg of gezond ogend xyleem. Bij de vatbare cultivar Lena trad afbraak van het xyleem op, dat daarbij armer aan syringyllignine werd, terwijl tevens in een vroeg stadium pectine werd gedemethyleerd. In ‘Lena’ werden slechts kleine hoeveelheden fytoalexinen gevonden, met name bij locaal opgetreden afweerreacties zoals gomvorming. Bij beide cultivars werden aanwijzingen voor afbraak van hemicellulosen gevonden.
    Notes: Abstract Minute pieces of xylem and other tissues from stems of healthy and fungus-infected plants of two carnation cultivars Novada and Lena were investigated for lignification (lignin/polysaccharide ratios) and lignin composition by means of pyrolysis mass spectrometry and pyrolysis gas chromatography mass spectrometry. This technique proved also very effective for the localization of dianthramide phytoalexins which accumulate in carnation after infection withFusarium oxysporum f.sp.dianthi. The composition of healthy tissues from both cultivars was practically the same. In the resistant cultivar Novada, infection induced a change from guaiacyl-syringyl lignin into a mainly guaiacyl lignin in the gum-occluded parts of the xylem. Considerable amounts of the phenolic amide dianthalexin and of other dianthramide phytoalexins were present in occluded xylem, but not in adjacent phloem, medulla or unoccluded xylem. Xylem from susceptible ‘Lena’ suffering degradation was characterized by a loss of syringyl groups from the lignin and by demethylation of pectin in an early stage of infection. Small quantities of dianthalexin and other dianthramide phytoalexins were found in ‘Lena’ when local defense responses (particularly occlusion) had occurred. In both cultivars evidence for degradation of hemicellulose was found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01974252
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