Search results for "Medium"
showing 10 items of 3746 documents
Enamel Prism Patterns of European Hominoids — and Their Phylogenetical Aspects
1981
Everybody concerned with questions of taxonomy and phylogeny knows that a large part of information used to classify fossil vertebrates is derived from teeth. This comes from the reasoning that teeth are the best mineralized portions of the skeleton and thus usually also the best preserved remains. The best preserved portion of teeth is again the most highly mineralized — the enamel. That the enamel shows a so-called prism pattern, which differs markedly within mammals and also within the primates, is well known since Carter (1922) and Regan (1930) published articles concerning the variability of enamel prism patterns. These were for the first time described by Tomes in 1848. An intensive i…
Micropropagation of Genista aetnensis [(Raf. ex Biv.)DC]
2015
Genista aetnensis [(Raf. ex Biv.)DC] is a large deciduous shrub or small tree native to the Italian islands of Sardinia and Sicily. Being winter hardy and characterized by high plasticity in altitude and ecology, the species is grown in gardens and landscaping, both for flower and for its attractive shape. Genista species are generally propagate by seed or semi hardwood cuttings. In this report an efficient in vitro technique for propagation of G. aetnensis was investigated. Multiple shoots were induced on nodal segments of a mature plant of Genista aetnensis . The Murashige and Skoog medium, augmented with different concentrations of benzyladenine either singly or in combination with indol…
Gravity-Driven Infiltration and Subsidence Phenomena in Posidonia oceanica Residues
2019
A simplified infiltration model for highly permeable porous media was introduced, assuming the matric potential gradient as negligible compared to the gravitational gradient. This model enabled us to determine the delay time, i.e., the time that the water front takes (from the beginning of rainfall) to reach the bottom of the highly permeable layer. Posidonia oceanica (Linnaeus) Delile residues were used as a porous media, in order to study the infiltration process that provides salt leaching under natural rainfall when these residues are arranged in a storage area, before reusing. By using a laboratory rainfall simulator, delay times were measured to verify the applicability of the aforeme…
Radon levels in the Valencian community (Spain). I. Results in the province of Valencia (1990–1991)
1995
Abstract Two-day radon screening measurements with charcoal canisters were made in buildings in the province of Valencia throughout the years 1990 and 1991. An average indoor concentration of 34 Bq m −3 was found, and 9% of all measurements exceeded the recommended EPA limit of 148 Bq m −3 .
BLOOD PARASITES AND MALE FITNESS IN THE PIED FLYCATCHER
1993
In vertebrates the effect of parasites on host ecology has almost been ignored. Recently the view that well-adapted parasites do not harm their hosts has been challenged and there is growing evidence that parasites do have a present-day effect on a great variety of host fitness components. The pied flycatcher is a small migratory passcrine bird. Any decrease in condition caused by disease should affect its ability to cope with physical demands of migration. Here we examine whether blood parasites have any effect on male arrival time. Males infected with Trypanosoma arrived on average 2 days later than males with no Trypanosoma infection. Infected males also had shorted tails and tended to h…
Arthropod-induced neoplastic formations on trees change photosynthetic pigment levels and oxidative enzyme activities
2005
Abstract In order to test the hypothesis that arthropod-induced neoplastic formations on trees affect biochemical characteristics of both the newly formed galls and host plant tissues, biochemical characteristics with a possible adaptive role were determined in nine gall-former–host tree combinations. Photosynthetic pigments, extractable protein content, and oxidative enzyme activities were determined in gall tissues, leaf tissues of galled leaves, and leaves on ungalled tree branches. Neoplastic tissues were characterized by a low content of photosynthetic pigments, decreased chlorophyll a/b ratio, lower extractable protein content, and decreased activities of peroxidase and polyphenol oxi…
Azide and chloride binding to carboxypeptidase A in the presence of L-phenylalanine
1990
The interaction of chloride with native and cobalt (Co)-substituted carboxypeptidase-A (CPD) has been investigated by 35Cl nuclear magnetic resonance (NMR) spectroscopy in the presence and absence of L-Phe. The affinity constants of azide and chloride toward the Co(II)CPD·L-Phe complex have been measured by electronic spectroscopy. The correlation times determining T1 and T2 for the 35Cl nuclei are related to movements inside the cavity. In the presence of L-Phe, the anions bind to the metal with a relatively high affinity at pH values below 6. Anion binding to the Co enzyme can be analyzed in terms of the three protonation state model for the enzyme (EH2 α EH α E). In the presence of L-Phe…
Effect of organic matrices on the determination of the trace element chemistry (Mg, Sr, Mg/Ca, Sr/Ca) of aragonitic bivalve shells (<i>Arctica …
2010
The element chemistry of biogenic carbonates can provide important data on past environments. However, the Sr/Ca and Mg/Ca ratios as well as the Mg and Sr concentrations of biological carbonates, especially aragonitic bivalves often depart from apparent thermodynamic equilibrium. When measured in situ by means of LA-ICP-MS, the Mg concentration is often substantially enriched (two- to threefold) near the organic-rich, annual growth lines. To test the hypothesis that some organic components exert a major influence on the skeletal metal content, the element chemistry of different shell components (insoluble organic matrix, IOM; dissolved CaCO3 and soluble organics, SOM) of Arctica islandica w…
Ucriol, an epoxy-diterpene from Sideritis syriaca
1983
Abstract The isolation of a new epoxy-diterpene from the inflorescence of Sideritis syriaca (S. sicula Ucria) is described. Its structure and stereochemistry were established by spectroscopy and partial synthesis.
Prenylated benzopyran derivatives from two Polyalthia species
1996
Two new benzopyran derivatives, (6E,10E)-isopolycerasoidol and polycerasoidin methyl ester, have been isolated from a methanolic extract of the stem bark of Polyalthia cerasoides. Their structures were established on the basis of chemical and spectral evidence. Polyalthia sclerophylla contains (6E,10E)-isopolycerasoidol, besides the known polycerasoidin and polycerasoidol. In addition, a known phenylpropene derivative, trans-asarone, has also been isolated from both species and fully characterized.