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Digitale Medien

Seed dispersal and changing seed characteristics in a Pinus halepensis Mill. forest after fire (1997)

Saracino, A. ; Pacella, R. ; Leone, V. ; [weitere]

Springer

Plant ecology 130 (1997), S. 13-19

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ISSN: 1573-5052

Schlagwort(e): Aleppo pine ; Colour ; Fire ; Predation ; Recruitment ; Seed

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract Seed density, seed colour and the number of seed damaged by birds were monitored for several months, after a late-spring fire, in two Aleppo pine (Pinus halepensis Miller) stands growing in South Italy. In one stand (S(1)) the trees were completely burned ('charred’), in the other one (S(2)) the trees were only ‘scorched’, with a crown in part still alive after fire. 37% and 61% of seeds were released during the first month, respectively in S(1) and S(2). Damaged seeds accounted for 43% and 23% of seeds collected in the whole period, respectively in the charred and in the scorched stand. In both stands the percentage of empty seeds increased in late-dispersed seed lots. The colour of released seeds changed with time: dark grey-brown seeds were released at first, whereas late-dispersed seeds showed a yellowish colour. The principal component analysis performed on the categorical colour variables produced a good discrimination between seed lots collected at different dates. Seed dispersal and the characteristics of released seeds have been discussed in relation to the post-fire recruitment process and, in particular, to the possibility that the predation risk by granivorous birds may be reduced by a mimicry effect of seeds to the underlying soil.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009765129920

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Digitale Medien

Synthesis of 1,1-dichloro-2,2-bis(4-hydroxyphenyl)-ethylene via ammonia or methylamine dehydrochlorination. A bisphenol for the preparation of highly flame-resistant polycarbonates (1980)

MacLaury, M. R. ; Chan, A. D. ; Colley, A. M. ; [weitere]

New York : Wiley-Blackwell

Journal of Polymer Science: Polymer Chemistry Edition 18 (1980), S. 2501-2511

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Details

ISSN: 0360-6376

Schlagwort(e): Physics ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie

Notizen: Ammonia used as both reactant and solvent has been shown to dehydrochlorinate 1,1,1-tri-chloro-2,2-bis(4-hydroxyphenyl)ethane smoothly to 1,1-dichloro-2,2-bis(4-hydroxyphenyl)ethylene. The reaction is complete in 1 hr at 100°C, and after two crystallizations from methanol/water affords polymerizable quality monomer for the synthesis of highly flame-resistant polycarbonates. The use of organic solvents in combination with ammonia does not offer any rate advantages over pure ammonia. Primary and secondary amines also can be used to effect the dehydrochlorination but, except for the methylamine, are significantly less reactive and lead to less pure product than amonia.

Zusätzliches Material: 4 Ill.