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11

Electronic Resource

Phytomass structure of natural plant communities on spodosols in southern Venezuela: the Bana woodland (1985)

Bongers, F. ; Engelen, D. ; Klinge, H.

Springer

Plant ecology 63 (1985), S. 13-34

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ISSN: 1573-5052

Keywords: Bana ; Leaves ; Phytomass ; Root/shoot ratio ; Spodosol ; Structure ; Tropical forest ; Wetland

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Bana, or Low Amazon Caatinga is an evergreen sclerophyllous woodland. It occurs on bleached quartz sands in the lowlands of SW Venezuela, where it occupies relatively small ‘islands’ amidst Tall Amazon Caatinga which is exclusively developed on tropaquods. There is an outer vegetation belt about 20 m in width in which trees over 10 m in height occur (Tall Bana); its structure and floristic composition resemble Tall Amazon Caatinga. Low Bana (maximum tree height usually below 5 m) follows next. The central part is occupied by Open Bana in which even lower trees are very widely spaced. Destructive phytomass sampling was carried out for chemical analyses in seven plots along a 150 m line across the zonation. The total dry matter of living plants including roots of Tall Bana (30–32 kg/m2) compares rather well with 41 kg/m2 in Tall Amazon Caatinga. This is only 9–14 kg/m2 in Low Bana, and 4–6 kg/m2 in Open Bana. The average root % of total phytomass increases from 41% in Tall Bana to 63% in Low Bana, and is 88% in Open Bana. Average total dry dead above-ground phytomass (including standing trees and stumps) declines from 1 kg/m2 in Tall Bana to 0.2 kg/m2 in Open Bana. An accumulation of dead matter in Low and Open Bana, relative to the above-ground phytomass of living plants, is noted and this contrasts with the general absence of raw humus in the soil. Eighty-two species of woody plants (dbh≥1 cm) were recorded on the total plot area (640 m2); 90% of the species are also known to occur in Tall Amazon Caatinga. The species number declines from 59 in Tall Bana to 18 in Open Bana. Mesophylls sensu strictu dominate in Tall Bana, while notophylls are dominant in Low and Open Bana. Herbaceous species are less numerous: most of them belong to the Araceae, Bromeliaceae, Orchidaceae, Droseraceae, Eriocaulaceae and Xyridaceae.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00032183

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12

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Interaction of hydrological systems and eutrophication of the Loosdrecht Lakes (1986)

Engelen, G. B.

Springer

Aquatic ecology 20 (1986), S. 17-25

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ISSN: 1573-5125

Keywords: Loosdrecht Lakes ; hydrology ; water transport ; eutrophication

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The history of eutrophication of the Loosdrecht Lakes system and the differences in trophic state of the compartments of this system are described from a hydrological point of view. Groundwater movement was found to be of paramount importance. This groundwater transport induced a horizontal surface water transport with concomitant biomass from Loosdrecht Lakes to Lake Breukeleveen, which explains partly the more eutrophic situation in the latter lake. The article summarizes several internal WOL-reports (ENGELEN and KAL, 1985; HETTLING, 1985a, b; KUHNEL, 1985; TEUNISSEN, 1985).

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02291147

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13

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Neutronenbeugungsmessungen an SrBr2 · H2O und Srl2 · H2O, symmetrisch und asymmetrisch gebundene Kristallwasser-moleküle (1988)

Engelen, B. ; Kellersohn, Th. ; Kuske, P. ; [et al.]

Weinheim : Wiley-Blackwell

Zeitschrift für anorganische Chemie 566 (1988), S. 49-54

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ISSN: 0044-2313

Keywords: Chemistry ; Inorganic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Description / Table of Contents: Neutron Diffraction Studies of SrBr2 · H2O and SrI2 · H2O, Symmetrically and Asymmetrically Bonded Water MoleculesSingle crystal neutron diffraction studies were performed on the isostructural (space group Pnma) SrBr2 · H2O and SrI2 · H2O. Lengths and structure of the hydrogen bonds are correlated with Raman and IR spectroscopic data. The bifurcated and trifurcated H-bonds present are altogether significantly stronger than linear ones with similar H…Br and H…I distances, respectively. In the case of SrI2 · H2O, the H-bonds of the two hydrogen atoms of the water molecules exhibit equal strength (symmetric water molecule) as shown by the respective OH vibrational energies despite the different H…I distances. The water molecule of SrBr2 · H2O is asymmetrically bonded (different strength of the H-bonds).

Notes: An den isotypen Hydraten SrBr2 · H2O und SrI2 · H2O (Raumgruppe Pnma) wurden Einkristallneutronenbeugungsmessungen vorgenommen. Die Bindungslängen sowie die Anordnung der verzweigten Wasserstoffbrücken werden mit Raman- und IR-spektroskopischen Daten korreliert. Die zwei- bzw. dreifach verzweigten Wasserstoffbrücken sind insgesamt signifikant stärker als gleich lange lineare Brücken zu Br--und I--Ionen. Die von den beiden Wasserstoffatomen des SrI2 · H2O gebildeten H-Brücken sind, wie die entsprechenden OH-Schwingungsfrequenzen zeigen, trotz der unterschiedlichen H…I-Abstände gleich stark (H2O symmetrisch). Das Kristallwassermolekül des SrBr2 · H2O ist asymmetrisch gebunden (unterschiedlich starke H-Brücken).

Additional Material: 1 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/zaac.19885660107

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14

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Kristallstruktur sowie FIR- und Ramanspektren von GaCrSe3 (1988)

Lutz, H. D. ; Engelen, B. ; Fischer, M. ; [et al.]

Weinheim : Wiley-Blackwell

Zeitschrift für anorganische Chemie 566 (1988), S. 55-61

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ISSN: 0044-2313

Keywords: Chemistry ; Inorganic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Description / Table of Contents: Crystal Structure, F.I.R., and Raman Spectra of GaCrSe3The crystal structure of GaCrSe3 oP20 was determined by single crystal X-ray methods (final R = 1.6% for 949 observed reflections, I 〉 2σI). GaCrSe3 crystallizes in the orthorhombic space group Pnma with Z = 4 (CuTaS3 type) and a = 1011.82(7), b = 373.45(3), and c = 1239.2(1) pm. The structure is built up on rectangular columns in [010] of edge shared GaSe4 tetrahedra and CrSe6 octahedra of the sequence (GaSe4)(CrSe6)2(GaSe4) in [101] and [101], respectively, which are connected via the corners in such a manner that channels in [010] of trigonal prismatic cavities are formed. The single crystals were grown by vapour phase transport method using I2 as transporting agent. The f.i.r. and Raman spectra of GaCrSe3 as well as a group theoretical treatment of the phonon modes are reported. In the ternary system Ga2Se3-Cr2Se3, monoclinic Ga1,3Cr0,7Se3 and hexagonal CrGa1,66Se4 (FeGaS4-type) have been established additionally to the orthorhombic GaCrSe3.

Notes: Die Kristallstruktur der bisher nicht beschriebenen Verbindung GaCrSe3oP20 wurde anhand von Einkristalldaten bestimmt (R = 1,6% für 949 beobachtete (I 〉 2σI) Reflexe). GaCrSe3 kristallisiert in der orthorhombischen Raumgruppe Pnma mit Z = 4 (CuTaS3-Typ) sowie a = 1011,82(7), b = 373,45(3) und c = 1239,2(1) pm. Der Struktur liegen rechteckige Säulen in [010] aus kantenverknüpften CrSe6-Oktaedern und GaSe4-Tetraedern der Folge (GaSe4)(CrSe6)2(GaSe4) in [101] bzw. [101] zugrunde, die über die Ecken der Oktaeder- und Tetraederbaueinheiten so verknüpft sind, daß in [010] angeordnete Kanäle mit trigonal-prismatischen Lücken gebildet werden. Die Darstellung von Einkristallen des GaCrSe3 erfolgte durch Gasphasen-transport mit Iod. Das FIR- und Ramanspektrum des GaCrSe3 sowie die Schwingungsabzählung der Gitterschwingungen dieses Strukturtyps werden mitgeteilt. Neben dem orthorhombischen GaCrSe3 existieren im System Ga2Se3-Cr2Se3 monoklines Ga1,3Cr0,7Se3 und hexagonales CrGa1,66Se4 (FeGa2S4-Typ).

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/zaac.19885660108

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15

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Beiträge zur Chemie des Schwefels. 115. Kristall- und MolekülStruktur von BenzopentathiepinProfessor Günther Rienäcker gewidmet (1979)

Fehér, F. ; Engelen, B.

Weinheim : Wiley-Blackwell

Zeitschrift für anorganische Chemie 452 (1979), S. 37-42

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ISSN: 0044-2313

Keywords: Chemistry ; Inorganic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Description / Table of Contents: Contributions to the Chemistry of Sulfur. 115. Crystal and Molecular Structure of BenzopentathiepineThe structure of benzopentathiepine has been determined from three-dimensional single-crystal X-ray data. The crystal are monoclinic, space group P21/c, with 4 molecules in the unit cell of dimensions a = 6.942(4) Å, b = 10.223(10) Å, c = 13.015(8) Å, β = 102,15(10)°. The conformation of the seven-membered ring is the chair form. Details of the conformation are discussed. Bond distances, bond angles, and dihedral angles are compared with those in other molecules, which have similar structure.

Notes: Die Struktur von Benzopentathiepin wurde aus Einkristalldaten röntgenographisch bestimmt. Die Kristalle sind monoklin, Raumgruppe P21/c, mit 4 Molekeln in der Elementarzelle. Die Gitterkonstanten sind: a = 6,942(4) Å, b = 10,223(10) Å, c = 13,015(8) Å, β = 102,15(10)°. Der siebengliedrige Ring liegt in der Sesselkonformation vor. Einzelheiten der Konformation werden diskutiert. Bindungslängen und -winkel sowie die Diederwinkel werden mit denen anderer Molekeln ähnlicher Struktur verglichen.

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/zaac.19794520106

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16

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Zur Kenntnis der Hydrate des Bariumchlorids. Röntgenographische, thermoanalytische, Raman- und IR-spektroskopische Untersuchungen (1979)

Lutz, H. D. ; Becker, W. ; Mertins, Ch. ; [et al.]

Weinheim : Wiley-Blackwell

Zeitschrift für anorganische Chemie 457 (1979), S. 84-90

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ISSN: 0044-2313

Keywords: Chemistry ; Inorganic Chemistry

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Description / Table of Contents: Hydrates of Barium Chloride. X-ray, Thermoanalytical, Raman, and I.R. DataIn the system BaCl2—H2O the hydrates BaCl2 · 2 H2O, BaCl2 · 1 H2O, BaCl2 · 1/2 H2O, and BaCl2 · uH2O were obtained. X-ray powder data, i.r. and Raman spectra, as well as thermoanalytical measurements (TG, DTA) are reported. BaCl2 · 1 H2O and BaCl2 · 1/2 H2O, which are both isotype with the corresponding hydrates of SrCl2, were prepared by dehydration of BaCl2 · 2 H2O or by back hydration of anhydrous BaCl2 with the calculated amounts of water. BaCl2 · uH2O (u ≍ 1) is formed as the primary product by the reaction of anhydrous BaCl2 with water vapour at room temperature. Preparation methods of salt hydrates by controlled back hydration of the anhydrous salts are reported.

Notes: Im System BaCl2—H2O wurden folgende Hydrate erhalten: BaCl2 · 2 H2O, BaCl2 · 1 H2O, BaCl2 · 1/2 H2O und BaCl2 · uH2O. Röntgenpulverdaten, IR- und Raman-Spektren sowie das Ergebnis thermoanalytischer Messungen (TG, DTA) werden mitgeteilt. BaCl2 · 1 H2O und BaCl2 · 1/2 H2O, die mit den entsprechenden Hydraten des SrCl2 isotyp sind, werden beim Entwässern von BaCl2 · 2 H2O oder durch Umsetzen von wasserfreiem BaCl2 mit der berechneten Menge Wasser erhalten. BaCl2 · uH2O (u ≍ 1) bildet sich als primäres Reaktionsprodukt bei der Umsetzung von wasserfreiem BaCl2 mit Wasserdampf bei Raumtemperatur. Die Darstellung phasenreiner niederer Salzhydrate durch kontrollierte Rückbewässerung der wasserfreien Salze wird beschrieben.

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/zaac.19794570109

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