86,830 research outputs found
Effect of salinity, temperature, organic and inorganic nutrients on growth of cultured Fibrocapsa japonica (Raphidophyceae) from the northern Adriatic Sea
No full textThe effects of temperature, salinity, inorganic and organic nutrients on the growth and physiological performance of Fibrocapsa japonica have been investigated in strains isolated from the northern Adriatic Sea, where intense and regular blooms have occurred since 1997 in coastal waters during summer. Strains isolated at different times and from different locations appeared homogeneous in terms of both physiological responses and molecular (ITS-5.8S rDNA) characteristics. Growth rates were higher at temperatures between 20 and 26 degrees C and in a salinity range of 30-35 (0.7 div day(-1)). The temperature of 16 degrees C inhibited growth, more markedly at the lowest and highest salinity values, a result also confirmed by a lower photosynthetic efficiency and by an increase in cell volume due to impaircd division. Higher cell concentrations were obtained with macronutrients at f/2 levels than in a fivefold diluted medium. Comparing the utilization of 200 mu M nitrate to that of different N sources (inorganic and organic), F japonica showed an efficient growth with equivalent amounts of ammonia, area and amino acids, such as glycine and tryptophan; glutamate was less effective, while methionine had toxic effects. Organic phosphate, administered as glycerophosphate, could also sustain F japonica growth, probably on account of an alkaline phosphatase whose activity was enhanced in the presence of the organic form. Vitamins were necessary for growth, though no further stimulation was observed when a surplus of vitamin B12 (3 nM) was added. The addition of 11.7 mu M iron instead of 2.3 mu M, as well as that of humic acid, with or without macronutrients, did not enhance algal growth either. These results led us to hypothesise that E japonica blooms became more frequent due to a general seawater temperature increase and to the availability of organic forms which, in coastal anthropized areas, are especially abundant in summer periods
Comparison between post-Hartree-Fock and DFT methods for the study of strength and mechanism of cleavage of Hg-C bond
No full textTHEORETICAL-STUDY OF THE ELECTRONIC-STRUCTURE AND OF THE MERCURY-CARBON BONDING OF METHYLMERCURY(II) COMPOUNDS
No full textEffect of salinity, temperature, organic and inorganic nutrients on growth of cultured Fibrocapsa japonica (Raphidophyceae) from the northern Adriatic Sea
No full textThe effects of temperature, salinity, inorganic and organic nutrients on the growth and physiological performance of Fibrocapsa japonica have been investigated in strains isolated from the northern Adriatic Sea, where intense and regular blooms have occurred since 1997 in coastal waters during summer. Strains isolated at different times and from different locations appeared homogeneous in terms of both physiological responses and molecular (ITS-5.8S rDNA) characteristics. Growth rates were higher at temperatures between 20 and 26 °C and a salinity range of 30-35 (0.7 div d-1). The temperature of 16°C inhibited growth, more markedly at the lowest and highest salinity values, a result also confirmed by a lower photosynthetic efficiency and by an increase in cell volume due to impaired division. Higher cell concentrations were obtained with macronutrients at f/2 levels than in a five-fold diluted medium. Comparing the utilization of 200 μM nitrate to that of different N sources (inorganic and organic), F. japonica showed an efficient growth with equivalent amounts of ammonia, urea and amino acids, such as glycine and tryptophan; glutamate was less effective, while methionine had toxic effects. Organic phosphate, administered as glycerophosphate, could also sustain F. japonica growth, probably on account of an alkaline phosphatase whose activity was enhanced in the presence of the organic form. Vitamins were necessary for growth, though no further stimulation was observed when a surplus of vitamin B12 (3 nM) was added. The addition of 11.7 μM iron instead of 2.3 μM, as well as that of humic acid, with or without macronutrients, did not enhance algal growth either. These results led us to hypothesise that F. japonica blooms became more frequent due to a general seawater temperature increase and to the availability of organic forms which, in coastal anthropized areas, are especially abundant in summer periods
The chimera of 2D- and 1D-graphene magnetization by hydrogenation or fluorination: critically revisiting old schemes and proposing new ones by ab initio methods
No full textGraphene is an ideal candidate material for spintronics due to its layered structure and peculiar electronic structure. However, in its pristine state, the production of magnetic moments is not trivial. A very appealing approach is the chemical modification of pristine graphene. The main obstacle is the control of the geometrical features and the selectivity of functional groups. The lack of a periodic functionalization pattern of the graphene sheet prevents, therefore, the achievement of long-range magnetic order, thus limiting its use in spintronic devices. In such regards, the stability and the magnitude of the instilled magnetic moment depending on the size and shape of in silico designed graphane islands and ribbons embedded in graphene matrix will be computed and analysed. Our findings thus suggest that a novel and magneto-active graphene derivative nanostructure could become achievable more easily than extended graphone or nanoribbons, with a strong potential for future spintronics applications with a variable spin-current density
, DFT DESCRIPTION OF THE MAGNETIC PROPERTIES AND ELECTRON TRANSFER IN DINUCLEAR DI-M-OXO BRIDGED MANGANESE COMPLEXES
No full textA comparative study of Cocconeis scutellum Ehrenberg and its varieties (Bacillariophyta)
No full textWe present an ultrastructure-based revision (using light and electron microscopy) of the type species of the genus Cocconeis, C. scutellum var. scutellum, and four often-mentioned but poorly described, morphologically related varieties: C. scutellum var. baldjikiana, C. scutellum var. clinoraphis, C. scutellum var. parva, C. scutellum var. posidoniae. In addition, we introduce three new taxa, C. scutellum var. gorensis var. nov., C. scutellum var. posidoniae f. decussata f. nov. and C. scutellum var. sullivanensis var. nov. The taxonomic relationships between these varieties and the remaining validly described C. scutellum varieties are analyzed on the basis of their ultrastructural differences. We also provide additional information on the geographical distribution of all analyzed C. scutellum taxa. © 2008 by Walter de Gruyter
Effect of salinity, temperature, organic and inorganic nutrients on growth of cultured Fibrocapsa japonica (Raphidophyceae) from the northern Adriatic Sea
No full textThe effects of temperature, salinity, inorganic and organic nutrients on the growth and physiological performance of Fibrocapsa japonica have been investigated in strains isolated from the northern Adriatic Sea, where intense and regular blooms have occurred since 1997 in coastal waters during summer. Strains isolated at different times and from different locations appeared homogeneous in terms of both physiological responses and molecular (ITS-5.8S rDNA) characteristics. Growth rates were higher at temperatures between 20 and 26 8C and in a salinity range of 30–35 (0.7 div day1). The temperature of 16 8C inhibited growth, more markedly at the lowest and highest salinity values, a result also confirmed by a
lower photosynthetic efficiency and by an increase in cell volume due to impaired division. Higher cell concentrations were obtained with macronutrients at f/2 levels than in a fivefold diluted medium. Comparing the utilization of 200 mMnitrate to that of different N sources (inorganic and organic), F. japonica showed an efficient growth with equivalent amounts of ammonia, urea and amino acids, such as glycine and tryptophan;
glutamate was less effective, while methionine had toxic effects. Organic phosphate, administered as glycerophosphate, could also sustain F. japonica growth, probably on account of an alkaline phosphatase whose activity was enhanced in the presence of the organic form. Vitamins were necessary for growth, though no further stimulation was observed when a surplus of vitamin B12 (3 nM) was added. The addition of 11.7 mM iron instead of 2.3 mM, as well as that of humic acid, with or without macronutrients, did not enhance algal growth either. These results led us to hypothesise that F. japonica blooms became more frequent due to a general seawater temperature increase and to the availability of organic forms which, in coastal anthropized areas, are especially abundant in summer periods
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