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1

Digitale Medien

Nutrient dynamics within amazonian forests (1988)

Cuevas, Elvira ; Medina, Ernesto

Springer

Oecologia 76 (1988), S. 222-235

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ISSN: 1432-1939

Schlagwort(e): Amazonian forests ; Root growth ; Nutrient release ; Organic matter decomposition

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary Relationships between fine root growth, rates of litter decomposition and nutrient release were analysed in a mixed forest on Tierra Firme, a Tall Amazon Caatinga and a Low Bana on podsolized sands near San Carlos de Rio Negro. Fine root growth in the upper soil layers (root mat+10 cm upper soil) was considerably higher in the Tierra Firme forest (1117 g m-2 yr-1) than in tall Cattinga (120) and Bana (235). Fine root growth on top of the root mat was stimulated significantly by added N in Tall Caatinga and Low Bana forests, by P in Tierra Firme and Bana forests, and by Ca only in the Tierra Firme forest. Rate of fine root growth in Tierra Firme forest on fresh litter is strongly correlated with the Mg and Ca content of litter. Rate of litter decomposition was inversely related to % lignin and the lignin/N ratio of litter. Litter contact with the dense root mat of the Tierra Firme increased rates of disappearance for biomass, Ca and Mg as compared with litter permanently separated or lifted weekly from the root mat to avoid root attachment. Nitrogen concentration of decomposing litter increased in all forests, net N released being observed only in Caryocar glabrum and Aspidosperma megalocarpum of the Tierra Firme forest after one year of exposure. Results emphasize the differences in limiting nutrients in amazonian forest ecosystems on contrasting soil types: Tierra Firme forests are particularly limited by Ca and Mg, while Caatinga and Bana forests are limited mainly by N availability.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00379956

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2

Digitale Medien

Nutrient dynamics within amazonian forest ecosystems (1986)

Cuevas, E. ; Medina, E.

Springer

Oecologia 68 (1986), S. 466-472

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ISSN: 1432-1939

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary A comparative analysis on the rate of fine litterfall and its associated nutrient fluxes was carried out in a mixed forest on Tierra Firme, a tall Amazon Caatinga and a Bana on podsolized sands near San Carlos de Rio Negro. There was seasonality in leaf fall and total litterfall in mixed forest and tall Amazon Caatinga forest but no definite trend in the Bana. Litterfall curves were significantly correlated among sites indicating common regulating factors in the three forests. Leaf litter from mixed forest on Tierra Firme was richer in N with extremely low Ca and Mg concentrations; tall Amazon Caatinga litter had higher P and Mg concentration, while Bana litter was low in N but K concentration was twice as high as in the other two forests. Annual fine litterfall in Tierra Firme mixed forest was nearly 4 times higher than in Bana, But N flux was 10 times higher, while Ca and Mg fluxes were similar. Tall Amazon Caatinga had Ca and Mg fluxes in litterfall 2–3 times higher than the other two forests. Within-stand efficiency of nitrogen, calcium and magnesium use, as measured by biomass/nutrient ratios, differentiates Tierra Firme from Caatinga and Bana forest: Tierra Firme has the lowest N, but the highest Ca and Mg use efficiencies. Higher P use efficiency was measured in Bana followed by Tierra Firme and Caatinga; while Tierra Firme and Caatinga showed similar higher K use efficiencies than Bana. N/P ratios indicates that Tierra Firme forest is limited by P availability, while low N availability predominates in Caatinga. Bana appears limited by both N and P. These differences probably relate to variations in degree of sclerophylly and leaf duration which determine leaf nutrient concentrations in the ecosystems studied.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01036756

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3

Digitale Medien

Transitions de phases du pDCB et diagrammes de phases pDCB-pDBB et pDCB-pBCB (1988)

Labrador, M. ; Tauler, E. ; Cuevas-Diarte, M. A. ; [weitere]

Springer

Journal of thermal analysis and calorimetry 34 (1988), S. 537-542

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ISSN: 1572-8943

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Beschreibung / Inhaltsverzeichnis: Zusammenfassung Die Phasendiagramme der zwei binären organischen Systemen [p-Dichlorbenzen (pDCB)/p-Bromchlorbenzen (pBCB) und p-Dichlorbenzen/p-dibrombenzen (pDBB)] wurden mittels Röntgendiffraktometrie und thermischer Methoden untersucht. Die Definition und Anwendung eines „Formfaktors“ des thermischen Signals erlaubt, auf das Vorliegen einer sehr nahen eutektischen Invariante in beiden Systemen zu schließen. Diese eutektische Invariante ist auf das Polymorphiephänomen [α-β] zurückzuführen, das bei reinem pDCB und an pDCB reichen Gemischen zur Geltung kommt. Andererseits kann, besonders beim zweiten System, die sehr geringe Weite der Fest-Flüssig-Schleife (〈1 K) nur mit Hilfe des „Formfaktors“ ermittelt werden.

Kurzfassung: Резюме С помощью рентгенофа зового анализа и термических методов определены фазовые диаграммы для органи ческих бинарных сист ем п-дихлорбензол — п-бро мхлорбензол и пдихло рбензол — п-дибромбензол. Опре деление и использова ние «порядкового коэффи циента» термических сигнало в позволило предполо жить существование в обои х системах очень узко й эвтектической инвар иантности. Эта эвтект ическая инвариантность обус ловленаа−β) полимор физмом, затрагивающим п-дихл орбензол и обогащенн ые им смеси. С другой стороны, использование «поря дкового коэффициент а» позволило, особенно в случае второй систем ы, определить очень мал ую (〈 1 К) ширину солидус — ликвидус петли.

Notizen: Abstract The phase diagrams of two organic binary systems [p-dichlorobenzene (pDCB) — p-bromochlorobenzene (pBCB)] and [p-dichlorobenzene—p-dibromobenzene (pDBB)] have been determined by X-ray diffraction and thermal methods. The definition and the use of a “form factor” of the thermal signals allows to involve the existence of a very narrow eutectic invariant in the two systems. This eutectic invariant is due to the polymorphism phenomena [α-β] affecting pure pDCB and rich pDCB alloys. On the other hand in particular for the second system, only the use of the “form factor” permits the very small width of the solidus-liquidus loop (〈1 K) to be determined.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01913196

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4

Digitale Medien

Polymorphisme du tetrachloro-1,2,4,5 benzene et du tetrabromo-1,2,4,5 benzene (1989)

Mondieig, D. ; Cuevas-Diarte, M. A. ; Haget, Y.

Springer

Journal of thermal analysis and calorimetry 35 (1989), S. 2491-2500

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ISSN: 1572-8943

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Beschreibung / Inhaltsverzeichnis: Zusammenfassung Eine Kombination dreier thermoanalytischer Methoden (Hot-stage Polarisationsmikroskop, DSC, Guinier-Lenne) ermöglichte die Bestimmung des polymorphen Verhaltens von Tetra-1,2,4,5-X-benzol (X=Cl, Br). Es wurde eine thermische, kalorimetrische und kristallographische Charakterisierung durchgeführt. Diese Untersuchung wirft ein interessantes Problem auf: dieβ-Phase (P21/a, stabil bei RT) von Tetrachlorbenzol besitzt eine ähnliche Konfiguration wie die zwei Festphasen P21/a von Tetrabromobenzol. Welche dieser beiden Formen ist mit Tetrachlorbenzol isomorph?

Kurzfassung: Резюме Комбинация трех мето дов термического ана лиза (поляризационная мик роскопия с нагревом, ДСК, Гюнье-Ле нн) позолила установи ть полиморфный характе р 1,2,4,5-тетра-Хбензолов, где X=Сl или Вг. Проведен ы термические, калориметрические и кристаллографическ ие измерения. Проведе нное исследование выявил о интересную проблем у:β-фаза тетрахлорбенз ола (устойчива при ком натной температуре и имеюща я симметрию P2j/a) подобна двум твердот ельным фазам тетрабр омбензола с симметрией Р21/а. Какая из этих двух форм действительно и зоморфна сβ-фазой тетрахлорбензола, тр ебует дальнеших иссл едований.

Notizen: Abstract Combination of three techniques of thermal analysis (hot stage polarising microscope, DSC, Guinier-Lenne) enabled the determination of the polymorphic behaviour of tetra 1,2,4,5-X benzene (X=Cl, Br). Thermal, calorimetric and crystallographic characterizations have been carried out. This study puts forward an interesting problem: theβ phase (P21/a, stable at room temperature) of the tetra chlorobenzene has similar arrangement to the two solid piases P21/a of tetra bromobenzene. Which one of these two forms is actually isomorphic with tetra chlorobenzene.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01911913

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5

Digitale Medien

A methodology for evaluating a location as a selection site for an international plant breeding program (1989)

Cuevas-Pérez, Federico ; Amézquita, María Cristina ; Rosero, Manuel J.

Springer

Euphytica 43 (1989), S. 165-172

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ISSN: 1573-5060

Schlagwort(e): Oryza sativa ; rainfed rice ; Central America ; Mexico ; yield and disease selection ; selection site ; probability of coincidence in selection ; probability of divergence in rejection ; target environments

Quelle: Springer Online Journal Archives 1860-2000

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Summary A method for comparing locations as selection sites based upon their abilities to predict yield and disease reaction over a target region is proposed. The probability of coincidence in selection for a site is defined as the probability for a line selected at the site to be selected at other sites within the region. The probability of divergence in rejection is defined as that associated with regional selection of a line given that is discarded by the site where selection is being conducted. The ideal selection site would maximize the probability of coincidence in selection and minimize the probability of divergence in rejection. The method is illustrated using a set of data from the rice yield nurseries of the International Rice Testing Program for Latin America planted under the rainfed conditions of Central América and México during the period 1978–1984. Five locations were compared for their predictive ability in selecting for the rainfed rice growing region, based on yield and disease reaction. Selection for yield was defined as performance superior to the best check in each location. Selection for disease reaction was based on an index derived from the Standard Evaluation System for Rice for diseases of regional importance. Locations varies 10–15 percent in their selection coincidence with the region for both yield and disease selection criteria applied independently.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00037909

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6

Digitale Medien

Ethanol production from sugarcane bagasse holocellulose. Coupled systems for saccharification, xylose isomerization and yeast fermentation (1988)

Salomón, Raquel L. ; Cuevas, Carlos M. ; Ellenrieder, Guillermo R.

Springer

World journal of microbiology and biotechnology 4 (1988), S. 383-392

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ISSN: 1573-0972

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Beschreibung / Inhaltsverzeichnis: Résumé L'ajout d'une étape d'isomérisation à un système couplé pour la production d'éthanol à partir de bagasse de cane à sucre a permis la fermentation éthanolique tant du xylose que du xylulose parSaccharomyces cerevisiae. Le rendement en g d'éthanol par g de bagasse prétraitée a crû selon la méthode de prétraitement: de 0.185 à 0.24 en cas de prétraitement à la soude caustique, de 0.11 à 0.18 dans le cas de Ca(OH)2 et de 0.26 à 0.29 dans le cas de la méthode combinée Ca(OH)2-NaCl.

Kurzfassung: Resumen Se estudio la inculsión de una etapa de isomerización en el sistema de columnas acopladas, de producción de etanol a partir del bagazo de caña de azúcar, con el fin de permitir asi la fermentación alcohólica de la xilosa. El rendimiento expresado como g etanol/g bagazo pretratado, aumentó dependiendo del tipo de pretratamiento: 0.185 a 0.24 para el pretratamiento con NaOH; 0.11 a 0.18 para el correspondiente a Ca(OH)2 y 0.26 a 0.29 para un tratamiento combinado de Ca(OH)2-NaCl.

Notizen: Summary Ethanol production from sugarcane bagasse holocellulose. Coupled systems for saccharification, xylose isomerization and yeast fermentation. An isomerization step was added to the coupled system for ethanol production from sugar cane bagasse in order to allow the alcoholic fermentation of xylose as xylulose bySaccharomyces cerevisiae. The yield (g ethanol/g pretreated bagasse) was improved according to the method of pretreatment: 0.185 to 0.24 with NaOH pretreatment, 0.11 to 0.18 for Ca(OH)2 and 0.26 to 0.29 for a combined Ca(OH)2/NaCl method.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00940162

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