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  • 1
    ISSN: 1573-2932
    Schlagwort(e): atmospheric aerosol ; acid digestion procedure ; atomic absorption spectrometry ; heavy metal ; lead
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract This paper presents a simple, reliable, economical, safe, accurate and reproducible method for atmospheric aerosol lead determination in glass fiber filters, consisting on an acid digestion procedure and atomic absorption spectrometry quantification. The acid digestion is accelerated by the use of a microwave oven with capped Teflon PFA vessels, and a two steps power and time program. The mixture of 10 mL HNO3 and 1 mL HF was selected between many tries, for both economic and environmental reasons. The use of direct standards for quantification is proposed instead of added standards on filters, using background correction (deuterium lamp). The filter lead content quantification was carried out through blank analyses. Lead determinations were carried out then in 2629 samples of atmospheric aerosol at three sampling points in the city of Cartagena (Spain), from 1990 to 1994. We present the annual average of these values for each year and sampling location.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    ISSN: 1573-2932
    Schlagwort(e): atmospheric aerosol ; acid digestion procedure ; atomic absorption spectrometry ; heavy metal ; lead
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Energietechnik
    Notizen: Abstract This paper presents a simple, reliable, economical, safe, accurate and reproducible method for atmospheric aerosol lead determination in glass fiber filters, consisting on an acid digestion procedure and atomic absorption spectrometry quantification. The acid digestion is accelerated by the use of a microwave oven with capped Teflon PFA vessels, and a two steps power and time program. The mixture of 10 mL HNO3 and 1 mL HF was selected between many tries, for both economic and environmental reasons. The use of direct standards for quantification is proposed instead of added standards on filters, using background correction (deuterium lamp). The filter lead content quantification was carried out through blank analyses. Lead determinations were carried out then in 2629 samples of atmospheric aerosol at three sampling points in the city of Cartagena (Spain), from 1990 to 1994. We present the annual average of these values for each year and sampling location.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Polar biology 22 (1999), S. 90-92 
    ISSN: 1432-2056
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Stone-collecting behaviour was studied in a colony of chinstrap penguins (Pygoscelis antarctica), to explore the likely importance of nest size. We randomly categorised nests as control or experimental. All nests were weighed at the beginning of the incubation period. In the experimental nests we removed stones constituting 50% of their initial weight, while in the control nests all the stones were returned after weighing. All nests were weighed again either prior to or just after hatching to determine likely changes in their weight. The mean weight increase of experimental nests was significantly higher than the mean weight increase of control nests. Size represents a property of the nest which individuals continuously monitor throughout the incubation/brooding period, reacting to changes in it by appropriate changes in stone-collecting rate.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Nutrient cycling in agroecosystems 43 (1995), S. 131-136 
    ISSN: 1573-0867
    Schlagwort(e): phosphorus ; titanium ; fertilizer efficiency ; plant nutrition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract To study the titanium effect on P nutrition, a greenhouse experiment withCapsicum annuum L., cv. Bunejo plants growing under differential P fertilization was conducted. All the plants were grown under identical conditions and they only differred in the P fertilization and in Ti supply. Plant biomass production of the Ti-untreated plants was affected by the diminution of the P-feed, but the plants growing under the lowest P supply did not showed any deficiency symptom during the crop cycle. All the Ti-treated plots showed a significative increase of the plant biomass against their corresponding untreated references. The biomass enhancement was mainly caused by the increase of the fruit yield with an absolute enhancement of 62% in the plants growing under the lowest P feed, and of 45% in the plants with a complete P support.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 1432-1939
    Schlagwort(e): Key words Antarctica ; Breeding failure ; Serological variables ; T-cell-mediated immunity ; Timing of breeding
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Health status and immunocompetence have been proposed as important factors affecting individual variation in the attainment of breeding condition in birds. We studied individual variation in serological variables indicating health status (blood sedimentation rate, haematocrit, `buffy coat' layer, proportions of different types of leucocytes) in two groups of breeding chinstrap penguins Pygoscelis antarctica with breeding dates 9 days apart. We sampled these individuals shortly after hatching of their young and at the end of the chick-raising period. A group of failed breeders was also sampled. Birds of both sexes were included. We also measured the T-cell-mediated immune response as indicated by an in vivo hypersensitivity response to an intradermal injection of a mitogen (phytohaemagglutinin) in early and late breeders. Sex had no significant effect on most variables. Late breeders had poorer health (more leucocytes, especially heterophils and lymphocytes) and a lower T-cell-mediated immune response than early breeders. Failed breeders were more similar to late than to early breeders. Early breeders suffered a decline in health status throughout the chick-raising period. The impact of pathogens on variation in life history traits in avian populations may be important even in extreme Antarctic environments.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Polar biology 17 (1997), S. 131-140 
    ISSN: 1432-2056
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  To evaluate levels of essential (zinc and copper) and non-essential (mercury and cadmium) heavy metals, 34 species of organisms from different areas close to the Antarctic Peninsula were analysed. These included algae, filter-feeders, omnivorous invertebrates and vertebrates. Mercury was not detected, while cadmium was found in the majority of organisms analysed (detection limit was 0.05 ppm for both metals). The highest cadmium concentration was observed in the starfish Odontaster validus. Anthozoans, sipunculids and nudibranchs showed maximum levels of zinc, while the highest copper level was found in the gastropod Trophon brevispira. Mercury and cadmium levels in fishes were below the detection limit. Concentrations of essential and non-essential metals in birds were highest in liver followed by muscle and eggs. Cadmium and mercury levels in muscle of southern elephant seals were above the detection limit, whereas in Antarctic fur seals they were below it. The objective of the study was to gather baseline information for metals in Antarctic Ocean biota that may be needed to detect, measure and monitor future environmental changes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    International journal of anthropology 14 (1999), S. 219-226 
    ISSN: 1824-3096
    Schlagwort(e): Menopause ; Havana ; Anthropometrics ; Body composition ; Discriminant Analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The aim of the present study is to analyze the morphologic changes occurring along the period of a woman's life thatareknown as climacterium. Our sample consists of 648 women from different provinces of Cuba, but who lived in Havana for at least 15 years. Morphological variables such as height, weight, biliocristal and biachromial diameters and six subcutaneous fat skinfolds were measured. With regard to the menopausic condition, the sample was divided into three subpopulations: premenopausic, naturally menopausic and surgically menopausic (when the two ovaries had been removed). Age at menopause was calculated by both the “retrospective” (49.45±0.49) and “status quo” (48.83±0.02) methods. The results obtained point towards morphological differences between pre- and postmenopausic women. We observed greater accumulations of fatty tissue in the suprailiac regions of postmenopausal females. Lean body mass represents a bigger fraction of the total body weight in women who are still menstruating. In the case of surgically menopausic women, they are at a mid-distance between the premenopausic and naturally menopausic subpopulations. A discriminant analysis was carried out which confirmed the results previously observed. From this analysis it appeared the body mass index and the subcutaneous skinfolds are the variables that discriminante, that is, separate, the three subsamples.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    ISSN: 1432-1955
    Schlagwort(e): Key words Ivermectin ; Nematodes ; GABA receptor ; Trichinella spiralis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The value of the γ-aminobutyric acid (GABA) receptor of nematodes as a target for ivermectin's mode of action remains unclear. Using binding assays, we examined extracts from Trichinella spiralis muscle larvae for the presence of [3H]-ivermectin and [3H]-GABA binding sites. Tissue preparations displayed affinity binding sites for [3H]-ivermectin with a dissociation constant (K d) of 83 nM and a receptor density (Bmax) of 145 fmol/mg protein. We also identified a specific [3H]-GABA binding activity with a K d of 1.2 μM and a Bmax of 4.78 pmol/mg protein. In competition studies, ivermectin was found to be a competitive inhibitor of specific [3H]-GABA binding activity with an inhibition constant (K i) of 3.39 nM, suggesting that GABA receptors could be implicated in the mechanism of action of ivermectin in nematodes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Parasitology research 84 (1998), S. 757-759 
    ISSN: 1432-1955
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Characterization of the levamisole receptor was performed with total extracts of Trichinella spiralis muscle larvae using binding assays with tritiated levamisole ([3H]LEV, 291 GBq/mmol). We detected a specific [3H]LEV binding activity with a dissociation constant (Kd) of 4.76 μM and a receptor density (Bmax) of 2.14 pmol/mg of protein. In inhibition studies, only dimethylphenylpiperazinium iodide (DMPP) and hexamethonium were found to be competitive inhibitors of the [3H]LEV binding with an inhibition constant (Ki) of 31.04 and 4.43 μM, respectively, whereas d-tubocurarine and α-bungarotoxine had no effect on [3H]LEV binding activity, and procaine and atropine potentiated the [3H]LEV-receptor binding. All these data support the idea that levamisole acts as a cholinergic agonist in T. spiralis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    ISSN: 1432-1955
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Humoral and cellular immune responses to Fasciola hepatica excretory-secretory products (ESPs) in primary and secondary experimental infections in goats were studied. Primary infection induced the development of chronic subclinical fascioliasis that did not affect the establishment of flukes coming from the secondary infection, as the same percentages of recovered flukes were found in both groups. The specific IgG response to F. hepatica ESPs was similar in primary and secondary infections; challenge flukes did not induce any modification in the IgG response. The specific lymphocyte response to F. hepatica ESPs was absent in most of the infected goats, both primarily and secondarily infected. A modulation of the nonspecific cellular responses to mitogens was also observed. All infected goats showed a reduced proliferative response to concanavalin A and phytohemagglutinin. According to our results, humoral and cellular responses to F. hepatica ESPs in goats have no protective effect on the establishment of flukes and the development of disease in either primary or secondary infections.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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