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  • Column liquid chromatography  (86)
  • photosynthesis  (46)
  • taxonomy
  • Springer  (167)
  • 2000-2004
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  • 1
    Digitale Medien
    Digitale Medien
    Effect of folding and feeding by Cnaphalocrocis medinalis on photosynthesis and transpiration of rice leaves (1992)
    Springer
    Entomologia experimentalis et applicata 63 (1992), S. 101-102 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Cnaphalocrosis medinalis ; rice leaffolder ; Oryza sativa ; rice ; photosynthesis ; transpiration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00350352
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  • 2
    Digitale Medien
    Digitale Medien
    Assessment of Hg2+ toxicity to a N2-fixing cyanobacterium in long- and short-term experiments (1992)
    Springer
    BioMetals 5 (1992), S. 149-156 
    Details
    ISSN: 1572-8773
    Schlagwort(e): Hg2+ toxicity ; cyanobacterium ; Nostoc calcicola ; growth ; photopigments ; nucleic acids ; photosynthesis ; membrane integrity ; nutrient uptake ; enzymes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Toxicological responses of the filamentous N2-fixing cyanobacteriumNostoc calcicola Bréb. towards Hg2+ were studied to enumerate the decisive lethal events. In low-dose, long-term experiments (0.05–0.25 μm Hg2+, 10 days), photoautotrophic growth was severely inhibited with concurrent loss of photosynthetic pigments (phycocyanin〉chlorophyll α〉carotenoids) and nucleic acids. The termination of growth after a day 4 exposure to 0.25 μm Hg2+ has been attributed to the complete inhibition ofin vivo photosynthetic activity in the cyanobacterium (O2 evolution〉14CO2 incorporation). The elevated Hg2+ concentrations irreversibly damaged the cell membrance as observed under light microscopy, and as indicated by the leakage of intracellular electrolytes and phycocyanin. In high-dose, short-term experiments (0.5–20.0 μm Hg2+, up to 6 h), thein vivo activities of selected enzymes (glutamine synthetase 〉 nitrate reductase 〉 nitrogenase) were less inhibited by Hg2+ than the uptake of nutrient ions (NH 4 + 〉NO 3 − 〉PO 4 3− ).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01061321
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  • 3
    Digitale Medien
    Digitale Medien
    Sporobolomyces lactosus, a new species of ballistosporous yeast equipped with ubiquinone-10 (1992)
    Springer
    Antonie van Leeuwenhoek 61 (1992), S. 245-248 
    Details
    ISSN: 1572-9699
    Schlagwort(e): Sporobolomyces lactosus ; yeasts ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A new species of ballistospore-forming yeasts was recovered and its description given.Sporobolomyces lactosus, isolated from activated sludge treating petrochemical wastes, produces pinkish-coral to pink colored colonies, assimilates lactose and has Q-10 as the major ubiquinone.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00584231
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  • 4
    Digitale Medien
    Digitale Medien
    Contributions to a revision of the genusTrichosporon (1992)
    Springer
    Antonie van Leeuwenhoek 61 (1992), S. 289-316 
    Details
    ISSN: 1572-9699
    Schlagwort(e): Trichosporon ; white piedra ; systemic mycosis ; taxonomy ; nDNA ; rRNA ; ubiquinone systems ; basidiomycetous yeasts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The genusTrichosporon was revised using characters of morphology, ultrastructure, physiology, ubiquinone systems, mol% G+C of DNA, DNA/DNA reassociations and 26S ribosomal RNA partial sequences. A total of 101 strains was used, including all available type and authentic cultures of previously described taxa. Nineteen taxa could be distinguished, 15 of which having Q-9 coenzyme systems and 4 having Q-10. Sixteen previously described names were reduced to synonymy. One new species was described. The genus is characterized by the presence of arthroconidia. Few species possess further diagnostic morphological characters, such as the presence of appressoria, macroconidia or meristematic conidiation. The septa of two species were found to be non-perforate, while those of the remaining species contained dolipores at variable degrees of differentiation, with or without vesicular or tubular parenthesomes. All species were able to assimilate a large number of carbon compounds; visible CO2 production was absent. The genus was found to be fairly homogeneous on the basis of a phylogenetic analysis of partial 26S rRNA sequences, with the exception ofT. pullulans which proved to be unrelated. Most taxa were found to occupy well-defined ecological niches. Within the group of taxa isolated from humans, a distinction found be made between those involved in systemic mycoses and those which mainly caused public or non-public white piedras, respectively. One species was consistently associated with animals, while others came mainly from soil or water. One species was mesophilic and another psychrophilic.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00713938
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  • 5
    Digitale Medien
    Digitale Medien
    Role of pigments on algal communities and photosynthesis (1992)
    Springer
    Aquatic sciences 54 (1992), S. 321-330 
    Details
    ISSN: 1420-9055
    Schlagwort(e): Algal pigments ; algal communities ; photosynthesis ; Lake Lugano (Lago di Lugano)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A one-year study of phytoplankton, primary production and related physical and chemical factors was made in a Swiss basin of Lake Lugano (Lago di Lugano). The chlorophylls and 12 carotenoids were analyzed with a TLC technique. The carotenoid monitoring was considered to be particularly interesting, because the role of these pigments in freshwater algae is still very poorly documented by field studies. The dependence of photosynthesis on several factors was statistically evaluated. Evidence was found of light-adaptation phenomena. The variations of photosynthetic activity and efficiency largely depended on the light regime in the few days before the field observations and on the cellular content of chlorophylls and single carotenoids, whose concentrations in their turn were closely linked with light, temperature, average cell size, and with the actual species assemblage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00878144
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  • 6
    Digitale Medien
    Digitale Medien
    Seasonal changes of microbial populations in the sediments of the basins of Lugano and Agno (1992)
    Springer
    Aquatic sciences 54 (1992), S. 331-337 
    Details
    ISSN: 1420-9055
    Schlagwort(e): Heterotrophic bacteria ; sediments ; taxonomy ; seasonal variations ; aerobic bacterial population ; anaerobic bacterial population ; Lake Lugano (Lago di Lugano)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract This research was carried out with the aim to explore the heterotrophic microbial population of two sediments in different oxic conditions of the Lake of Lugano (Lago di Lugano). The values of the viable bacterial counts found in our sediment samples were typical for an eutrophic lake. The increase in the proportion of anaerobic to aerobic bacteria at 30 °C observed in the sediment samples of Agno may reflect the depletion of oxygen concentrations in the water column. The generaAeromonas, Pseudomonas, Bacillus andClostridium, as well as strains belonging to the Coryneform-group, represented the major taxonomic groups of heterotrophic bacterial communities in the water-sediment interface.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00878145
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  • 7
    Digitale Medien
    Digitale Medien
    High SO2 resistance ofClethra barbinervis established in a smoke-polluted area of Ashio, Tochigi Prefecture, Japan (1992)
    Springer
    Ecological research 7 (1992), S. 363-370 
    Details
    ISSN: 1440-1703
    Schlagwort(e): Clethra barbinervis ; interspecific difference ; intraspecific variation ; photosynthesis ; SO2 resistance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effect of SO2 on the photosynthesis ofClethra barbinervis collected from a smoke-polluted area near the Ashio copper smelter in Tochigi Prefecture was compared withC. barbinervis collected from a nonpolluted district in Tsukuba, Ibaraki Prefecture andQuercus mongolica var.grosseserrata grown in a nonpolluted field in Nagano Prefecture. The plants were exposed to 0.5–1.5 p.p.m. SO2 for 90 min (short-term) and to 0.3 p.p.m. SO2 for 31–39 days (long-term). TheClethra plants from both sites had a lower intrinsic stomatal conductance and photosynthetic rate thanQuercus plants. Short-and long-term fumigation caused stomatal closure inQuercus plants, but had little effect on the stomatal conductance ofClethra plants. Under short-term fumigation, nonstomatal photosynthetic inhibition per unit of absorbed SO2 was smallest inClethra plants from Ashio. Long-term fumigation caused photosynthetic decline and visible foliar injury toQuercus plants, but had no effect onClethra plants from Ashio. Consequently,Clethra plants from Ashio had a higher photosynthetic rate thanQuercus plants after long-term fumigation. These results suggest thatC. barbinervis populations in the smoke-polluted area of Ashio had evolved high SO2 resistance connected with SO2 detoxification ability in mesophyll cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02347103
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  • 8
    Digitale Medien
    Digitale Medien
    Sequence of the fourth and fifth Photosystem II Type I chlorophyll a/b-binding protein genes of Arabidopsis thaliana and evidence for the presence of a full complement of the extended CAB gene family (1992)
    Springer
    Plant molecular biology 19 (1992), S. 725-733 
    Details
    ISSN: 1573-5028
    Schlagwort(e): gene duplication ; photosynthesis ; RFLP ; Southern blots
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A second locus (Lhb1B) encoding Photosystem II Type I chlorophyll a/b-binding (CAB) polypeptides was identified in Arabidopsis thaliana. This locus carries two genes in an inverted orientation. The predicted sequences of the polypeptides encoded by these two genes show substantial divergence in their amino termini relative to each other and to the proteins encoded by the three Lhb1 CAB genes previously characterized [10], but little divergence within the predicted primary structure of the mature protein. DNA probes derived from seven additional types of tomato CAB genes, encoding chlorophyll a/b-binding polypeptides of several antenna systems of the photosynthetic apparatus, were tested against A. thaliana. Each of these hybridized in Southern blots to unique DNA fragment(s), demonstrating the existence of each of these different types of CAB genes in the genome of A. thaliana. The number of genes encoding each CAB type in A. thaliana was estimated to be similar to that of tomato.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00027069
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  • 9
    Digitale Medien
    Digitale Medien
    Cloning and sequencing of the petBD operon from the cyanobacterium Synechococcus sp. PCC 7002 (1992)
    Springer
    Plant molecular biology 20 (1992), S. 481-491 
    Details
    ISSN: 1573-5028
    Schlagwort(e): photosynthesis ; cytochrome b 6 ; gene regulation ; genome mapping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The genes encoding the photosynthetic cytochrome b 6 (petB) and subunit 4 (petD) have been cloned and sequenced from the unicellular, photoheterotrophic, transformable cyanobacterium Synechococcus sp. PCC 7002, formerly designated Agmenellum quadruplicatum. The gene arrangement was found to be similar to that reported in the cyanobacterium Nostoc PCC 7906. The DNA and derived protein sequences were compared to chloroplast and the other cyanobacterial sequences. By pulsed-field electrophoresis, the petBD operon and the petCA operon, encoding the Rieske iron-sulfur protein and cytochrome f, were found to be located on separate, unlinked,Not I-digested DNA fragments. ThepetBD operon was found on the third largest Not I fragment (NC-325) while the petCA operon was found on the second largest Not I fragment (NB-370). These results suggest the two operons are not in proximity. The 1.35 kb transcript was shown to be light-regulated. Transcripts from cells grown under constant illumination showed a decrease in petB transcript levels to undetectable levels within 2 h after the cells were placed in the dark. Upon reillumination, transcript levels rose to three-fold over that seen initially under constant illumination.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00040607
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  • 10
    Digitale Medien
    Digitale Medien
    Chlorophyll a/b-binding protein genes are differentially expressed during soybean development (1992)
    Springer
    Plant molecular biology 19 (1992), S. 217-230 
    Details
    ISSN: 1573-5028
    Schlagwort(e): chlorophyll a/b-binding protein genes ; Glycine ; LHCP II ; photosynthesis ; soybean ; ribulose-1,5-bisphosphate carboxylase genes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The levels of chlorophyll a/b-binding protein (Cab) gene polysomal poly(A)+ mRNA were quantitated throughout the development of Glycine max L. Cab mRNAs were abundant in young expanding leaves, representing 6.1% of the leaf mRNA population. Lower Cab mRNA levels were present in embryos, stems, and cotyledons of developing seedlings; the lowest levels were found in roots where they accounted for 0.04% of the polysomal poly(A)+ mRNA of this organ. To determine the contribution of different members of the Cab gene family to the Cab mRNA populations, a quantitative S1 nuclease reconstruction assay was developed. Cab3, Cab4, and Cab5 mRNAs were detected in all stages examined during soybean development but their levels underwent differential changes. Cab3 encodes the most abundant Cab mRNA in young leaves, developing embryos, and in Stage VII cotyledons from the developing soybean seedling. The levels of Cab mRNAs were compared to the levels of ribulose-1,5-bisphosphate carboxylase small subunit gene mRNA and differences in their patterns of accumulation were noted. Collectively these data indicate that during soybean embryogenesis developmental control mechanisms supersede light-regulatory signals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00027343
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  • 11
    Digitale Medien
    Digitale Medien
    Dimerization constant and single-channel conductance of Gramicidin in thylakoid membranes (1992)
    Springer
    The journal of membrane biology 126 (1992), S. 265-275 
    Details
    ISSN: 1432-1424
    Schlagwort(e): photosynthesis ; thylakoids ; electrochromism ; gramicidin ; conductance ; dimerization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Summary The effect of the pore-forming antibiotic gramicidin on pure lipid membranes is well characterized. We studied its action in protein-rich thylakoid membranes that contain less than 25% (wt/wt) acyl lipids. A transmembrane voltage was induced by flashing light, and its decay was measured and interpreted to yield the distribution of gramicidin over thylakoids, its dimerization constant and its single-channel conductance in this membrane. The distribution of gramicidin over the ensemble of thylakoids was immediately homogeneous when the antibiotic was added under stirring, while it became homogeneous only after 20 min in a stirred suspension that was initially heterogeneous. The dimerization constant, 5×1014 cm2/mol, was about 10 times larger than in pure lipid membranes. This was attributed to the upconcentration of gramicidin in the small fractional area of protein free lipid bilayer and further by a preference of gramicidin for stacked portions of the membrane. The latter bears important consequences with regard to bioenergetic studies with this ionophore. As gramicidin was largely dimerized from a concentration of 1 nm (in the suspension) on, the membrane's conductance then increased linearly as a function of added gramicidin. When the negative surface potential at the thylakoid membrane was screened, the conductance of a single gramicidin dimer agreed well with figures reported for bilayers from neutral lipid (about 0.5 pS at 10 mm NaCl). The modulation of the conductance by the surface potential in spinach versus pea thylakoids and between different preparations is discussed in detail.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00232323
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  • 12
    Digitale Medien
    Digitale Medien
    Effects of drought on chlorophyll fluorescence in potato (Solanum tuberosum L.). II. Relations between plant growth and measurements of fluorescence (1992)
    Springer
    Potato research 35 (1992), S. 35-40 
    Details
    ISSN: 1871-4528
    Schlagwort(e): water-stress ; photosynthesis ; yield
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Relations between measurements of the slow kinetics of chlorophyll fluorescence and growth and yield were examined in seven potato genotypes grown either fully irrigated or droughted from the time of plant emergence. Drought reduced total dry matter production and yields and increased tuber dry matter concentration. Drought increased harvest index in cv. Spunta, but decreased it in cv. Pentland Crown. Total dry matter production was correlated with each of constant fluorescence, variable fluorescence and the half life of the decay in variable fluorescence. These correlations were determined largely by the effect of treatment, and did not discriminate effectively between genotypes within a treatment.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02357720
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  • 13
    Digitale Medien
    Digitale Medien
    Effects of drought on chlorophyll fluorescence in potato (Solanum tuberosum L.). I. Plant water status and the kinetics of chlorophyll fluorescence (1992)
    Springer
    Potato research 35 (1992), S. 25-34 
    Details
    ISSN: 1871-4528
    Schlagwort(e): water-stress ; photosynthesis ; leaf water potential
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The slow kinetics of chlorophyll fluorescence were examined in seven potato genotypes grown either fully irrigated or droughted from the time of plant emergence. Constant and variable fluorescence (F o andF v respectively) declined with time in plants from both irrigated and droughted treatments, but the decline was greater in droughted than irrigated plants. However, the yield of variable fluorescence (F v/(F o+F v)) was unaffected by the drought treatment. The main effect of drought was upon the quenching of variable fluorescence. Both the half life of the decay of variable fluorescence (q1/2) and the secondary maximum (M) were significantly greater in the droughted plants than in those from the irrigated treatment. Significant differences between genotypes were found forF v/(F o+F v),M andq 1/2. Genotype-by-treatment interactions were non-significant for all the variables examined. Changes in chlorophyll fluorescence transients were not closely related to changes in leaf water potential.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02357719
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  • 14
    Digitale Medien
    Digitale Medien
    The genusBlepharispermum (Asteraceae, Heliantheae) (1992)
    Springer
    Plant systematics and evolution 182 (1992), S. 149-227 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Asteraceae ; Heliantheae ; Blepharispermum ; Revision ; taxonomy ; phylogeny ; cladistics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The palaeotropic genusBlepharispermum (Asteraceae, Heliantheae) is revised for the first time. Fifteen species from Africa, the Arabian Peninsula, Madagascar, India, and Ceylon are recognized. Two new species are described, viz.B. arcuatum andB. canescens. Aspects of the systematic position and morphology of the genus are discussed. A hypothesis of phylogenetic relationships is presented by way of a cladistic analysis. A key to all species in the genus as well as typification, descriptions, drawings and distribution maps are supplied. Chromosome counts of two species are reported.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00939188
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  • 15
    Digitale Medien
    Digitale Medien
    Genomic groups, morphology, and sectional delimitation in EurasianElymus (Poaceae, Triticeae) (1992)
    Springer
    Plant systematics and evolution 180 (1992), S. 1-13 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Angiosperms ; Poaceae ; Triticeae ; Elymus ; Genome analysis ; morphology ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Seven tetraploid species ofElymus, viz.E. sibiricus, E. caninus, E. gmelinii, E. semicostatus, E. caucasicus, E. parviglume, andE. longearistatus subsp.canaliculatus, representing five sections were studied morphologically and used in interspecific hybridizations. The aim was to investigate whether the present sectional delimitation of the genus was in agreement with genomic data and if there was a correlation between genome constitution and morphology. The study revealed: (i) further information on the genomic affinities between the different species, (ii) that there is no congruence between genome constitution of the species and current sectional delimitation, and (iii) that there is a correlation between genome constitution and morphology in the palea apex shape and in the size of cilia of the palea.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00940394
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  • 16
    Digitale Medien
    Digitale Medien
    Ruellia sect.Urceolata (Acanthaceae), a novel species complex from southern Mexico (1992)
    Springer
    Plant systematics and evolution 180 (1992), S. 221-225 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Angiosperms ; Acanthaceae ; Ruellia ; Speciation over short distances ; endemism ; taxonomy ; Flora of Mexico
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A new section in MexicanRuellia, R. sect.Urceolata comprising three species (includingR. cedilloi, spec. nova), endemic to Mexico, is described and illustrated. The taxonomic relationship and differentiation of the species are discussed. Evolution in Mexican Ruellas seems to be occurring at the diploid level.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00941152
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  • 17
    Digitale Medien
    Digitale Medien
    Hybrid speciation and radiation in the neotropical woody genusTocoyena (Rubiaceae) (1992)
    Springer
    Plant systematics and evolution 181 (1992), S. 143-169 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Angiosperms ; Rubiaceae ; Tocoyena ; Hybridization ; differentiation ; speciation ; homogamic complex ; tropical woody plants ; taxonomy ; Flora of South America
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The variation pattern of a large population ofTocoyena formosa in Botucatu, state of São Paulo, Brazil, and of other samples throughout the species area was analysed by morphometrical, statistical, ecological, and phytogeographical methods. Excessive variation and the remarkable coherence of two different character syndromes within this species strongly suggest that it has originated as a homogamic (diploid) hybrid complex. Possible parental species areT. brasiliensis, mainly from the Amazon region, andT. viscidula from the dry caatinga region of NE. Brazil.T. formosa has a much more extensive geographical range and greater ecological plasticity, ranging from the Amazon basin and the Guyanas throughout the Central Brazilian Plateau and from NE. to S. Brazil and Paraguay. Three (partly sympatric) varieties are distinguished withinT. formosa, i.e. var.formosa, var.pseudobrasiliensis (var. nov.), and var.microdon (comb. et stat. nov.). A provisional taxonomic revision, key, and conspectus covers the 12 accepted species ofTocoyena with blunt flower buds and ovate obtuse corolla lobes (group A, includingT. formosa); their distribution is shown in a map.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00937441
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  • 18
    Digitale Medien
    Digitale Medien
    Two new species of the diatom genusChaetoceros (Bacillariophyta) (1992)
    Springer
    Plant systematics and evolution 181 (1992), S. 217-226 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Diatoms ; plankton ; Chaetoceros ; New species ; morphology ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Two new planktonic diatom species of the genusChaetoceros are described herein:Ch. octagonus andCh. rectus, from material of Baja California coasts and the Gulf of California, respectively;Ch. rectus was also found in a sample from Australian waters.Ch. octagonus is a robust species, with a characteristic pyramidal valve shape, heavily silicified valves and setae, and one central rimoportula on every valve in the chain; it is compared with related species, which show a similar morphology, especially by electron microscopy. It belongs into subg.Chaetoceros, sect.Borealia. Ch. rectus is placed in subg.Hyalochaete, and provisionally within sect.Anastomosantia. Its major characters are: chains, cells, and setae are delicate and fragile, cells are joined in the chain by a “bridge” which connects sibling intercalary setae, valves and setae are weakly silicified, and one rimoportula is present on terminal valves only. Comparison is made with another species of the same section.Ch. rectus shows a different manner of chain-forming within the genus than previously described in the literature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00937445
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  • 19
    Digitale Medien
    Digitale Medien
    A new combination and a new species in the lichen genusCatapyrenium (lichenizedAscomycetes, Verrucariaceae) (1992)
    Springer
    Plant systematics and evolution 181 (1992), S. 255-260 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Pyrenocarpous lichens ; Verrucariaceae ; Dermatocarpon ; Catapyrenium ; Catapyrenium velebiticum comb. nov. ; Catapyrenium pyrenaicum spec. nova ; Systematics ; taxonomy ; Flora of Austria, Croatia, France, Spain, and Switzerland
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Catapyrenium pyrenaicum is described as new from northern Spain and adjacent France, and the new combinationCatapyrenium velebiticum is made. The new species differs fromC. velebiticum mainly in its laminal pycnidia. Remarks on taxonomy, ecology, and distribution of the species are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00937449
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  • 20
    Digitale Medien
    Digitale Medien
    2-Bromoacetyl-6-methoxynaphthalene: A useful fluorescent labelling reagent for HPLC analysis of carboxylic acids (1992)
    Springer
    Chromatographia 33 (1992), S. 13-18 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Fatty acids and bile acids ; Fluorogenic precolumn derivatization ; 2-Bromoacetyl-6-methoxynaphthalene
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The use of 2-bromoacetyl-6-methoxynaphthalene as a fluorogenic labelling reagent in pre-column derivatization for the HPLC separation of biologically active carboxylic acids (fatty acids and bile acids) has been investigated. The compound reacts (30 min. at 70°C) with carboxylic acids to give fluorescent esters that can be separated by reversedphase HPLC and detected at λ ex. 300 nm, λ em. 460 nm. The experimental conditions for the derivatization and chromatographic separation are discussed. Applications to the determination of valproic acid and chenodeoxycholic acid in pharmaceutical formulations are described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276844
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  • 21
    Digitale Medien
    Digitale Medien
    HPLC method for the simultaneous analysis of valproic acid and other common anticonvulsant drugs in human plasma or serum (1992)
    Springer
    Chromatographia 33 (1992), S. 37-40 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Valproic acid ; Simultaneous determination of anticonvulsants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The derivatizing procedure of Moody et al. [20] for valproic acid has been simplified and applied to the simultaneous HPLC determination of valproic acid (VPA), barbital (B), primidone (PRM), phenobarbital (PB) and carbamazepine (CBZ) in serum or plasma of epileptic patients. The sample is deproteinized with acetonitrile containing esterification agents and an aliquot of the supernatant is heated to 70°C for 15 min with 4-bromophenacyl bromide. The reaction mixture is analysed on a C18 column at ambient temperature, with gradient elution and with detection at 205 nm. The time required for the chromatographic analysis is 13 min; identification is based on retention time and quantification is by peak area determination with an internal standard. The calibration curves show good linearity in the range 6.25 to 100 mg/L. The detection limits at a signal: noise ratio ≥3, ranged from 1 mg/L for B and CBZ to 2–3 mg/L for PRM, PB and VPA. The method described for the simultaneous determination of the five drugs in the same plasma pool, correlated well with isocratic HPLC methods specific for each drug. The simultaneous procedure described allows a reproducible (CVs≤6.5% within run) and rapid (25 min for sample preparation: 13 min for chromatographic run) therapeutic monitoring of patients treated with VPA and two or more antiepileptic drugs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276848
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  • 22
    Digitale Medien
    Digitale Medien
    Porous polymer packings from vinyl ether derivatives for reversed-phase liquid chromatography (1992)
    Springer
    Chromatographia 33 (1992), S. 19-24 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Porous polymer spherical packings ; Vinyl ether ; Alkali resistance ; No abnormal adsorption
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Spherical, porous-polymer particles for column packing in high-performance liquid chromatography were prepared by suspension copolymerization of alkylvinyl ether with triethyleneglycol divinyl ether. The hydrophobicity of the packings was easily adjusted by changing the monomer ratio. The packings showed the usual reversed-phase liquid chromatographic properties, but did not sho abnormal retention, tailing and broadening of peaks and irreversible adsorption of ionic and aromatic substances, owing to the lack of ionic or aromatic groups. In addition, the packings were stable in alkaline solutions because of the relative alkali stability of C−O−C bonds as compared with CO−O and Si−O−C bonds in conventional packings.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276845
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  • 23
    Digitale Medien
    Digitale Medien
    Comparison study between indirect photometric and direct conductivity detection for anion exchange chromatography using naphthalenesulfonate derivatives as mobile phases (1992)
    Springer
    Chromatographia 33 (1992), S. 25-31 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Anion exchange ; Indirect photometric and direct conductivity detection ; Naphthalenesulfonate ; Inorganic anions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Indirect photometric and unsuppressed direct conductivity detection modes are examined using naphthalene mono-, di-, and tri-sulfonate as mobile phases for the separation of several anions such as F−, Cl−, NO2 −, Br−, NO3 −, SO4=,I−, and SCN− using a commercial anion exchange column. With all three mobile phases, conductivity detection shows better sensitivities and detection limits than indirect photometry. Conductivity detection is 5 to 16 times more sensitive than indirect photometry for all analytes. Detection limits achieved using these mobile phases are, for example, 0.04 ng and 0.1 ng for chloride ion with conductivity and indirect photometry, respectively. Both detection modes give wide linear ranges extending from at least 100 ppm to the detection limit of each anion which is generally about 0.02 ppm. Sulfur oxide anions such as dithionate and tetrathionate are separated using flow programming with naphthalenetrisulfonate as the mobile phase in less than 20 minutes. With both detection modes, desired chromatographic performance of these three eluents is achieved without pH adjustment of the mobile phase.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276846
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  • 24
    Digitale Medien
    Digitale Medien
    An enhanced liquid chromatographic method for 5-hydroxymethylfurfural determination in UHT milk (1992)
    Springer
    Chromatographia 33 (1992), S. 45-48 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Heat-treated milk ; Milk quality indicators ; 5-Hydroxymethyl-2-furfuraldehyde
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An enhanced method of HPLC for the determination of 5-Hydroxymethyl-2-furfuraldehyde (HMF) in fluid milk was perfected. Its resolving capacity permitted the specific separation of this compound. The real concentration (μmol/l) of HMF was determined and not the HMF value, as in the colorimetric analysis, where an intermediary coloured compound (HMF-TBA) is utilised. The optimum pH condition (pH=4.0–4.2) for the mobile phase to prevent overlapping between the HMF peak and the peaks of the other compound (α and β) that coeluted with the HMF and also the optimum organic solvent content (3% or 7%) were established. This is a sensitive, quick and safe method for the determination of HMF in fluid milk.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276850
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  • 25
    Digitale Medien
    Digitale Medien
    Ion-pair reversed-phase liquid chromatography of arsenic species on polymeric styrene-divinylbenzene packed columns with an alkaline aqueous mobile phase (1992)
    Springer
    Chromatographia 33 (1992), S. 581-585 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Arsenic compounds ; Polymeric styrene divinylbenzene phase ; Ion-pairing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The resolving power of an ion-pair reversed-phase liquid chromatography method, on a polymeric stationary phase (PRP-1) with an alkaline aqueous mobile phase (pH=9) containing tetrabutylammonium cation as ion-pairing agent, is compared with a traditional ion-pairing system using an octadecyl-modified silica column and a neutral aqueous mobile phase (pH=7.3). This chromatographic system (PRP-1 column) provides a rapid means for the determination of two of the most important arsenic species, arsenobetaine and arsenite. Addition of methanol (5%) to the aqueous mobile phase allows the differentation of arsenobetaine from the system peak when using UV detection.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02262252
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  • 26
    Digitale Medien
    Digitale Medien
    Comparison of provitamin A determination by normal-phase gravity-flow column chromatography and reversed-phase high performance liquid chromatography (1992)
    Springer
    Chromatographia 33 (1992), S. 133-137 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Gravity-flow column chromatography ; Provitamin A determination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The provitamin A content of some food samples was determined by methods involving MgO: Hyflosupercel gravityflow column chromatography (GFCC) and reversed phase high performance liquid chromatography (HPLC), the quantitation being done by external standardization (HPLC-ES) or internal standardization (HPLC-IS) with Sudan. The results obtained with α- and β-carotene in carrots, β-carotene and β-cryptoxanthin in papaya and β-carotene in tomato and kale agreed well, showing that any of the these techniques can be used, provided the analysis is done under optimum conditions. Good separation of the different provitamins using GFCC depends on the analyst's skill and visual acuity. HPLC-ES required a constant supply of provitamin standards, thus the varying purity of commercially available standards and the high instability of these compounds could pose grave problems. Due to the stability of Sudan, HPLC-IS appeared to be the method of choice although passage of the extract through a MgO: Hyflosupercel minicolumn was required prior to injection to separate chlorophylls, dihydroxy- and polyoxycarotenoids which would otherwise elute with Sudan. Nonconformity of the Sudan structure to those of the provitamins did not effect the quantitative results. The chromatographic separation, identity and quantification of the provitamins could be more easily established by using HPLC-IS, complemented with GFCC.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02275893
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  • 27
    Digitale Medien
    Digitale Medien
    Diastereoselective and enantioselective chromatography of the pyrethroid insecticides allethrin and cypermethrin (1992)
    Springer
    Chromatographia 33 (1992), S. 103-112 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Gas chromatography ; Chiral separations ; Allethrin ; Cypermethrin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Liquid and gas chromatographic separations of the pyrethroid insecticides allethrin and cypermethrin have been investigated with various achiral and chiral stationary phases. Diastercomeric and enantiomeric selectivity was observed for cypermethrin on a Pirkle-type chiral LC stationary phase, but very strong interactions and therefore long retention times prevented the separation of allethrin on this phase. Trans-allethrin isomers were separated on a chiral β-cyclodextrin RP-HPLC column while cypermethrin showed some difficulties on this phase due to isomerization. Diastereomeric but no enantiomeric selectivity by GC was achieved for cypermethrin with an apolar DB 5 capillary. GC separation of the diastereomers was used to study the selective photodegradation of cypermethrin isomers after forestry applications. Chiral β-cyclodextrin-based GC phases showed some enantioselectivity for cis- and trans-allethrin isomers. A separation of the eight isomers into six partially resolved peaks was achieved by GC with a coupled column consisting of chiral permethylated β-cyclodextrin and DB 1701 as stationary phases. This combination was used to characterize allethrin formulations intended for indoor use and to investigate allethrin products formed by ozonolysis of thin films of the insecticide.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02275888
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  • 28
    Digitale Medien
    Digitale Medien
    Estimation of diuretic drugs in biological fluids by HPLC (1992)
    Springer
    Chromatographia 33 (1992), S. 177-185 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Diuretics ; Screening and determination of diuretics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary This critical review of different methods proposed for the determination and screening of diuretics is directed mainly, because of its potential application, towards highperformance liquid chromatography.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02275902
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  • 29
    Digitale Medien
    Digitale Medien
    Peak recognition technique by a computer program copying the human judgement (1992)
    Springer
    Chromatographia 33 (1992), S. 218-224 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Peak ; Pattern recognition ; Prediction interval
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary It is still difficult to determine peaks and peak boundaries properly, though peak recognition is very important for the precision of quantitative data. A new computer program overcomes these problems using a method which is adapted from human judgements. The algorithm was developed for HPLC but can also be used in other fields of analytical chemistry.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276186
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  • 30
    Digitale Medien
    Digitale Medien
    High performance liquid chromatography of raw sugars and polyols using bonded silica gels (1992)
    Springer
    Chromatographia 33 (1992), S. 325-330 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Diol silica gels ; Carbohydrates ; Evaporative light scattering detection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Bonded silica columns have been evaluated for their ability to separate carbohydrates and polyols. Mobile phases consisting of dichloromethane/methanol produced the best separations in comparison with the acetonitrile/water mixtures commonly used with amino columns. Of all the bonded phases tested, LiChrospher Diol silica provided the best separations, and selectivities were not very different from those obtained on the most popular system using an amino bonded phase and acetonitrile/water as eluent. In addition, diol columns with a dichloromethane/methanol eluent offer excellent stability with no Schiff’s base formation of reducing sugars. Using an evaporative light scattering detector, low limit detection is obtainable (20 ng of glucose from a column) and gradient elution is quite feasible.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02275911
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  • 31
    Digitale Medien
    Digitale Medien
    Retention of some ring-substituted aniline derivatives by porous graphitized carbon. Dependence on physico-chemical parameters (1992)
    Springer
    Chromatographia 33 (1992), S. 356-360 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Porous graphitized carbon ; Ring-substituted aniline derivatives ; Electronic interactions ; Principal component analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The retention characteristics of 22 aniline derivatives were determined on a porous, graphitized-carbon column in unbuffered acetonitrile-water and methanol-water mixtures. Each aniline derivative gave symmetrical peaks in each eluent without buffers. Good linear correlations were found between the log k′ and the concentration of the organic component in the eluent. The slope and intercept values differed according to the type of organic modifier and the charcter, number and position of substituents, indicating the different selectivities of methanol and acetonitrile and the good separating power of the column. Multivariate mathematical-statistical calculations proved that the retention of ring-substituted aniline derivatives is mainly governed by electronic parameters and the hydrogen acceptor capacity of substituents.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02275918
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  • 32
    Digitale Medien
    Digitale Medien
    Determination of furosine in milk samples by ion-pair reversed phase liquid chromatography (1992)
    Springer
    Chromatographia 33 (1992), S. 374-376 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Ion-pairing ; Furosine ; Pyridosine ; Milk
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An ion-pair, reversed-phase, liquid chromatographic procedure using UV detection for quantitation of furosine is described. The standard plot was linear (r〉0.999) over a 5 ng range. An authentic synthesised sample of furosine was used for calibration. Commerical milk samples were analyzed by the described procedure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02275921
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  • 33
    Digitale Medien
    Digitale Medien
    Optimisation of data handling and detection conditions for automated chromatographic assay software (1992)
    Springer
    Chromatographia 33 (1992), S. 361-368 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Automated peak detection ; Discrete Fourier transform ; Frequency acquisition and filtering ; Peak detection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The principle of automated chromatographic peak detection and analysis software is summarized, and critical steps are systematically studied. As the only parameter to be entered is the acquisition frequency, evaluation of its effect on software performance is discussed. In the case of relatively noisy chromatograms, it is shown experimentally that numerous points per peak have to be taken, leading to quite fast computer acquisition procedures. The use of discrete Fourier transform filtration techniques can modify peak shapes and a comparative study evaluates the relative errors induced in the shapes and characteristics of the chromatographic profiles. Optimisation of filtering conditions is achieved and it is shown that for a filter position only 2% of the Nyquist frequency no deformation occurs in the chromatographic profile. Detection of the start and finish of chromatographic peaks is optimized according to a simple four step iterative procedure. In the case of simulations, the difference between the values used to simulate peaks and those calculated by the software are less than 1%.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02275919
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  • 34
    Digitale Medien
    Digitale Medien
    Simultaneous determination of 5′-deoxy-5-fluorouridine, 5-fluorouracil and its main metabolites in body fluids by HPLC (1992)
    Springer
    Chromatographia 33 (1992), S. 413-417 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Fluoropyrimidine drugs ; Pharmacokinetics of doxifluridine ; Chemotherapy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A reversed phase high performance liquid chromatographic method has been developed for the simultaneous determination of the pro-drug 5′-deoxy-5-fluorouridine (5′-dFUR), its metabolite 5-fluorouracil (5-FU) and some fluorinated pyrimidines involved in the metabolic activation process of 5-FU. The method has been used to monitor the bioavailability of 5′-dFUR and 5-FU in patients undergoing anticancer chemotherapy. Serum sample treatment involves addition of internal standard (5-bromouracil), protein precipitation with saturated ammonium sulphate solution and liquid-liquid extraction with ethyl acetate-isopropanol (90 ∶ 10 v/v). Urine is simply diluted with mobile phase and injected. The average recovery from serum (at 0.5 μg/mL level) was 95.0%±1.4 for 5′-dFUR and 86.3%±3.5 for 5-FU. A linear response extending over four decades of concentration was observed. Detection limits in the low ng/ mL range were obtained using a 250 μL sample size and a 20 μL injection volume. Within-day and between-day coefficients of variation were below 4 and 10%, respectively.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02262320
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  • 35
    Digitale Medien
    Digitale Medien
    Total and individual determination of carbamate pesticides by use of an integrated flow-injection/HPLC system (1992)
    Springer
    Chromatographia 33 (1992), S. 449-453 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Flow injection analysis ; Combined flow injection/HPLC ; Carbamate pesticides
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An integrated flow injection (FI)/HPLC system for the total and individual determination of carbamate pesticides (propoxur, carbofuran and carbaryl) is proposed. The determination is based on the alkaline hydrolysis of the analytes and subsequent coupling with diazotized sulphanilic acid to yield the monitored dyes with or without a prior separation step by HPLC in a C18 column. The calibration curves obtained are linear in the μg/ml range and r.s.d. values are between 0.5 and 3.7% in all instances. Injection of the sample into the FI manifold allows the total pesticide content in the sample to be screened. The manifold thus acts as a post-column reactor/detector of the chromatograph for samples with high overall carbamate content, which are also injected into the HPLC instrument. The performance was checked with contaminated water samples.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02262326
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  • 36
    Digitale Medien
    Digitale Medien
    Evaluation of the enantioselectivity towards β-blocking agents of the α1 glycoprotein type chiral stationary phase: Chiral AGP®glycoprotein type chiral stationary phase: Chiral AGP® (1992)
    Springer
    Chromatographia 33 (1992), S. 454-462 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; α1 glycoprotein ; Enantioseparation ; β-blocking agents
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The enantioselectivity of the α1 glycoprotein chiral stationary phase, Chiral AGP® has been evaluated for a number of β-blocking agents. A correlation has been found between the retention behaviour on this stationary phase and the hydrophobicity of the compounds. The separation factor α is higher for compounds that are well retained. Retention, and thus α, are also controlled by pH and the percentage of organic modifier in the mobile phase.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02262327
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  • 37
    Digitale Medien
    Digitale Medien
    Isocratic HPLC separation of aromatic hydrocarbons and fluorine-containing compounds using perfluoroalkyl polymer packings (1992)
    Springer
    Chromatographia 33 (1992), S. 473-477 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Perfluoroalkylated polymer-gel packings ; Aromatic and fluorine-containing compounds
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Porous, perfluoroalkylated polymer-gels for column packings in high-performance liquid chromatography (HPLC) were prepared by suspension polymerization of heptadecafluorodecyl arcylate and ethylene glycol dimethacrylate. The packings showed no abnormal retention for ionic or aromatic compounds, due to the lack of ionic or aromatic groups. In addition, the packings showed no excessive retention for strongly hydrophobic compounds which is often the case with long-chain, alkylated silica gels and polymer gels. This is due to the extremely low surface energy of perfluoroalkyl groups. Therefore, perfluoroalkylated polymer gels enable isocratic HPLC separation of solutes with significantly different hydrophobicity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02262330
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  • 38
    Digitale Medien
    Digitale Medien
    Comments on the paper “correlation between retention in liquid chromatography and the adsorption energy” by J. Kloubek (1992)
    Springer
    Chromatographia 33 (1992), S. 485-486 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Porous glass ; Surface free energy ; Film pressure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02262332
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  • 39
    Digitale Medien
    Digitale Medien
    Correlation between retention in liquid chromatography and the adsorption energy (1992)
    Springer
    Chromatographia 33 (1992), S. 478-484 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Porous glass adsorbents ; Surface free energy ; Oriented adsorption of hydrocarbons
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The relationship between the specific capacity factor (k/S, where k is the capacity and S is the surface area of the sorbent, in m2) in the liquid chromatography of aromatic hydrocarbons and the adsorption energy (-°GA) has been investigated. The previously published results, based on the calculation of the work of adhesion (WSA) from contact angles, were re-examined and a new hypothesis on interactions at interfaces was employed. Direct proportionality has been found between k/S and-°GA, which allows prediction of the chromatographic behavior of adsorbates on sorbents. The surface free energy components were calculated in order to determine-°GA in terms of the work of adhesion. The dispersion component of the surface free energy of glass was obtained from the adsorption isotherm of n-octane and it was found that the hydrocarbon molecules are adsorbed in an oriented position. The contact angles of liquids on the outer surface of porous solids do not yield reliable values of WSA and of the surface free energy components. A higher intermolecular attraction increases WSA and decreases the contact angle in pores.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02262331
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  • 40
    Digitale Medien
    Digitale Medien
    A high-performance liquid chromatographic method for the analysis of adenosine and some metabolites in the brain tissue of rats (1992)
    Springer
    Chromatographia 34 (1992), S. 563-567 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Adenosine and some metabolites ; Extraction from brain tissue ; Quantitative determination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An analytical procedure has been developed for the assay of adenosine and some metabolites in brain tissue extracts of rats. This paper reports the extraction method, the technique adopted to avoid enzymatic transformations and the chromatographic conditions for the identification and quantitation of these nucleosides and bases. Peaks in the chromatograms of brain tissue extracts were identified by retention times, absorbance ratios of reference compounds and by enzymatic peak-shift.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269864
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  • 41
    Digitale Medien
    Digitale Medien
    Influence of silica gel surface purity on the coverage density of chemically bonded phases (1992)
    Springer
    Chromatographia 34 (1992), S. 573-580 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Chemically bonded phases (CBP) ; Surface heterogenity ; Surface purification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The surface chemistry of eight silica-gels with different siliceous matrix structures have been described. The influence of surface impurities on the chemical modification process (coverage density) with monooctadecylsilane has been studied. The surfaces of the adsorbents, before chemical modification, were cleaned by extraction with 20% HCl. Bare and modified materials were characterized using different physico-chemical methods e.g.: SIMS, CP/MAS NMR, porosimetry, pH measurement, elemental analysis and chromatography (GC & HPLC). The presence of trace amounts of different metallic elements creating new adsorption centers on the surfaces of the packings, have been demonstrated. Moreover, it has been shown that washing of silica gel adsorbents increases the coverage density of alkylsilyl ligands and improves the chromatographic properties of prepared packings.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269866
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  • 42
    Digitale Medien
    Digitale Medien
    Zone electrophoretic sample treatment coupled on-line with column liquid chromatography for the determination of basic and acidic compounds in biological samples (1992)
    Springer
    Chromatographia 34 (1992), S. 581-588 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Zone-electrophoretic sample treatment ; Basic and acidic compounds ; Biological samples
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A modified valve arrangement for zone-electrophoretic sample treatment (ZEST)-which is coupled on-line with column liquid chromatography — is used to pretreat biological (plasma) samples. Carry-over of plasma proteins depends on the pH of the electrophoresis buffer. The determination of propranolol, metoprolol, cromolyn and salicylic acid demonstrates that both basic and acidic analytes can be isolated from the plasma matrix with high selectivity. Analogous piperazines, with different protein binding properties, were used to study the influence of protein binding on the recovery. It is shown that high protein can cause a decreased recovery.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269867
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  • 43
    Digitale Medien
    Digitale Medien
    HPLC analysis of the main oxindole alkaloids fromUncaria tomentosa (1992)
    Springer
    Chromatographia 34 (1992), S. 597-600 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Oxindole alkaloids ; Uncaria tomentosa
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The main oxindole alkaloids from the root bark ofUncaria tomentosa were separated by reversed phase HPLC with an acetonitrile/methanol/phosphate buffer solvent gradient. UV detection was carried out at 245 nm. The chromatographic parameters for the separation of the alkaloids were optimized by studying the impact of the pH value of the mobile phase and the column temperature on the separation efficiency of the analytical system. The best separation was achieved with a mobile phase pH of 6.6 and a column temperature of 15°C. The method developed is suitable for the qualitative characterisation and quantitative determination of oxindole alkaloids in crudeUncaria tomentosa extracts and phytopharmaceuticals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269869
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  • 44
    Digitale Medien
    Digitale Medien
    Indirect stereoselective determination of enantiomers of furprofen in human plasma by high-performance liquid chromatography (1992)
    Springer
    Chromatographia 34 (1992), S. 618-620 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Enantiomers of furprofen ; Human plasma
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A sensitive and stereoselective liquid chromatographic (HPLC) assay for the S and R enantiomers of furprofen in human plasma has been developed. The assay is based on derivatization with S(−)-1-phenylethylamine with formation of two diastereoisomeric derivatives and on their separation and quantitation using HPLC with uv detection. The method is linear from 25 to 600 ng ml−1 of both enantiomers, with a variation coefficient below 10.8%, and a detection limit of 20 ng ml−1. This procedure is suitable for pharmacokinetic studies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269873
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  • 45
    Digitale Medien
    Digitale Medien
    Solute-micelle association constants and correlation of octanol-water coefficients with hydrophobicity for polycyclic aromatic hydrocarbons by micellar chromatography (1992)
    Springer
    Chromatographia 34 (1992), S. 627-635 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Micelle-solute association constants ; Polynuclear aromatic hydrocarbons ; Octanol/water partition coefficients
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Sodium dodecyl sulphate, hexadecyltrimethylammonium bromide and polyoxyethylene(23) lauryl ether were investigated as mobile phases in the micellar liquid chromatography of polycyclic aromatic hydrocarbons of environmental concern. A wide range of surfactant concentrations were used and the retention parameters and distribution coefficients calculated. The trends in the retention data for the PAHs are discussed and several conclusions are presented concerning the partition coefficients when these surfactants are present in the mobile phase. Comparisons are made between the structural features of the compounds and their capacity factors, and the octanol/water partition coefficients are correlated with hydrophobicity for the PAHs studied.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269875
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  • 46
    Digitale Medien
    Digitale Medien
    Retention characteristics of chlorinated polycyclic aromatic hydrocarbons in normal phase HPLC. II. Chloro-substituted PAHs (1992)
    Springer
    Chromatographia 34 (1992), S. 115-120 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Normal phase separations ; Chloro-substituted polycyclic aromatic hydrocarbons ; Coupled column system ; Environmental samples
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The retention behaviour of chloro-substituted PAHs on several commercial normal bonded phase HPLC columns has been investigated. Chloro-substitution was shown to generally decrease the retention on stationary phases like amino-, diol- and nitrophenylpropyl-modified silica. Dimethylaminosilica exhibited more complex retention characteristics towards chloro-substituted PAHs. On this stationary phase, the position of the chlorine substituents on the aromatic solute seemed to be of greater importance for retention than on the amino-, nitro- and diolsilica. For some chloro-PAHs, the retention was shown to increase with the number of chloro-substitutions, probably due to the large affinity of the electron-rich nitrogen in the stationary phase for the electron deficient π-system of the chloro-PAHs. Chloro-substituted PAHs were strongly retarded on the electron donating 2-(1-pyrenyl)-ethylsilica (PYE) stationary phase. However, the molecular shape of the chloro-derivatives had a large influence on retention, which was considerably decreased for some nonplanar chloro-derivatives of chrysene and benz(a)anthracene. A two-dimensional back-flush HPLC method, consisting of a combination of a nitrophenylsilica column and a PYE column of matched lengths, was shown to be useful for clean-up of chloro-substituted PAHs in environmental samples.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276122
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  • 47
    Digitale Medien
    Digitale Medien
    A column switching technique for the determination of lidocaine and its metabolites in horse urine (1992)
    Springer
    Chromatographia 34 (1992), S. 143-145 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Column switching ; Lidocaine ; Horse urine analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A rapid method is described for the determination of lidocaine and its metabolites in horse urine using a column switching technique and HPLC analysis. This procedure offers a sensitive assay without the need for time consuming extractions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276127
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  • 48
    Digitale Medien
    Digitale Medien
    Cystine and cysteine analysis as the same phenylthiocarbamyl derivatives by HPLC in protein hydrolyzates (1992)
    Springer
    Chromatographia 34 (1992), S. 132-136 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Cysteine, cystine ; Phenylthiocarbamyl derivatives ; Protein hydrolyzates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A new approach is described, and a novel explanation presented, for the high performance liquid chromatographic analysis of cystine and cysteine as their phenylthiocarbamyl derivatives. PTC cystine and cysteine have been eluted with the same retention times and molar responses, most probably due to electrophilic attack of phenylisothiocyanate on cystine resulting in the scission of the disulfide bond yielding two moles of cysteine. Further, total PTC cystine and cysteine have been measured both in model solutions and in standard protein hydrolyzates (lysozyme, bovine albumin, ribonuclease) with the same linearity as the other ineteen amino acids. The reproducibility of the measurements, at the 250–750 pmole level, proved to be 4.1% (Relative Standard Deviation %) or less.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276125
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  • 49
    Digitale Medien
    Digitale Medien
    Retention behaviour of crown ethers and actinomycin D in reversed-phase HPLC (1992)
    Springer
    Chromatographia 34 (1992), S. 155-158 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Retention ; Crown ethers ; Actinomycin D ; Metal cation complexation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Retention of crown ethers in reverse-phase HPLC has been determined by their bonding ability with cations present in the eluent. The dependence of retention of crown ethers on cation concentration exhibits an inflection and makes it possible to calculate stability constant for the crown ether-cation complex. It is shown that in 75% MeOH retention of antitumor antibiotic, actinomycin D, depends on [Na+] and not on [K+] at concentrations of K+ from 5×10−7 to 10−1 mol l−1. Hence, actinomycin D may be classified as an ionophore-antibiotic.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276129
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  • 50
    Digitale Medien
    Digitale Medien
    Liquid chromatographic retention and separation of phenols and related aromatic compounds on reversed phase columns (1992)
    Springer
    Chromatographia 34 (1992), S. 146-154 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Phenolic compounds ; Optimisation of isocratic separations ; River water samples
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Isocratic column liquid chromatographic systems with UV absorbance detection at 280 nm have been developed for the separation of 29 phenolics and related compounds. The selectivity was investigated on silica-, carbon- and polymer-based separation columns for the separation of phenolic type of components. The effects of various acetonitrile/buffer mixtures, and pH of the mobile phase, and their impact on the retention of the phenols was assessed. Tables of retention times on the four columns for the 29 phenols with two different acetonitrile/buffer mixtures, together with the retention times at three pHs from 6.5 to 2.3 with varying levels of organic modifier on the LiChrospher RP 18 column are presented. As an application, the analysis of real river water samples from the Ebro river is described using a solid phase extraction step prior to injection into the chromatographic system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276128
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  • 51
    Digitale Medien
    Digitale Medien
    Microcolumn liquid chromatography on carbon sorbents (1992)
    Springer
    Chromatographia 34 (1992), S. 173-176 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Carbon packing materials ; Aromatic compound separation ; Eluent effect
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The retention volume dependences on the molar volume were found for aromatic compounds using liquid microcolumn chromatography. The contributions of the functional groups in molecules of these compounds to the total retention value were calculated from the capacity factor values. The comparison of capacity factor values for carbon sorbents and octadecyl-silicagel has shown that for several microcolumn separations the carbon sorbent column has a better selectivity and resolution than the octadecyl-silicagel column.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276133
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  • 52
    Digitale Medien
    Digitale Medien
    Synthesis of acceptor bonded phases for donor-acceptor liquid chromatography (1992)
    Springer
    Chromatographia 34 (1992), S. 177-181 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Synthesis of bonded stationary phases ; Acceptor ligands ; Normal phases ; PAHs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The synthesis of several electron-acceptor stationary phases has been reviewed the materials evaluated for their capacity to separate polyaromatic hydrocarbons (PAHs). Chemically bonded phases were obtained by the same procedure; the organosilane moiety is monofunctional and the HPLC behaviour is compared under identical conditions. Examples of PAHs separations are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276134
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  • 53
    Digitale Medien
    Digitale Medien
    Silanol group effect in C18 bonded phases in HPLC (1992)
    Springer
    Chromatographia 34 (1992), S. 182-184 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; C18 bonded phase ; Residual silanol groups ; Metal 5-Br-PADAP complexes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary If any residual (free) silanol groups remain at the surface of silica gel after bonding treatment, they may affect the retention of solutes since the dissociated groups (≡SiO−) will attract cations. The silanol group effect on the retention of cationic solutes will increase with increasing pH of the mobile phase but the effect will decrease with increasing hydrophobic-ion concentration at the C18 surface because such ions can mask the residual silanol groups. A method for the separation of metal complexes with 2-(5-bromo-2-pyridylazo)-diethylaminephenol (5-Br-PADAP) has been developed. The hydrophobic ion in the MeOH/H2O mobile phase was tetrabutylammonium (TBA).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02276135
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  • 54
    Digitale Medien
    Digitale Medien
    Michael Tswett's columns: Facts and speculations (1992)
    Springer
    Chromatographia 34 (1992), S. 342-346 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; History of chromatography ; Calcium carbonate stationary phase ; Chlorophyll
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Although Michael Tswett is the originator of chromatography, little is known about the performance of his chromatographic systems. His descriptions of the separation of plant pigments are detailed but nevertheless difficult to interprete by today's chromatographic theory. By our own experiments with the system calcium carbonate/benzene it was found that the separation factor of chlorophyll a and b is approx. 1.6 which means that less than 100 theoretical plates are necessary for separation. Tswett's columns with 50 μm particles and 2–3 cm of bed height presumably exceeded this plate number. His separations could have been impaired by mass overload and by a volume flow rate which was two orders of magnitude faster than the optimum.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02268366
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  • 55
    Digitale Medien
    Digitale Medien
    Factors influencing retention and resolution of substituted alkylbenzenes in reversed-phase liquid chromatography (1992)
    Springer
    Chromatographia 34 (1992), S. 347-356 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Isomeric substituted alkylbenzenes ; Retention and resolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The retention data of isomeric xylenes, ethyltoluenes and diethylbenzenes, and of mesitylene, benzene, toluene and ethylbenzene were obtained on a reversedphase column using methanol-water and ethanol-water mobile phases at four different temperatures. This database was used to relate the dependence of solute retention and resolution on the polarity of the mobile phase, solute dipole moment, and column temperature. The additivity of the free energy of the transfer of solute molecules or solute segments from the stationary phase to the mobile phase, was examined for the isomeric compounds. For this, the logarithm of the net retention volume was substituted for the free energy. Deviations from the additivity of free energies indicate that the separation of isomeric substituted alkylbenzenes is governed by their differential interactions with both the polar mobile phase and nonpolar stationary phase. Among the disubstituted alkylbenzenes,ortho-isomers favor the mobile phase more andpara-isomers tend to prefer the stationary phase more. Themeta-isomers are found to follow the additivity rule closely. These trends are amplified as the polarity of the mobile phase is increased indicating that these isomers are resolved better in water-rich mobile phases. These findings are substantiated by analogous results from gas-liquid chromatographic retention data, estimation of dipole moment effects, and examination of the entropic and enthalpic contributions to the net retention volume.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02268367
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  • 56
    Digitale Medien
    Digitale Medien
    Direct determination of Benzo[a]pyrene in oil distillates by on-line two-dimensional HPLC with column switching (1992)
    Springer
    Chromatographia 34 (1992), S. 376-380 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Column switching ; Polycyclic aromatics ; Oil distillates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A selective and sensitive HPLC method for the determination of Benzo[a]pyrene (B[a]p) in oil fractions by means of column switching is described. The diluted oil samples were injected directly onto a silica column with isooctane as eluent. After fast elution of the main part of the sample matrix, the B[a]p containing fraction was transferred on-line to a dinitro-aryl-modified silica column for final separation with isooctane/tetrahydrofuran. A detection limit of 50 ppt B[a]p was found when using fluorescence detection.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02268371
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  • 57
    Digitale Medien
    Digitale Medien
    Gradient high performance liquid chromatography of block copolymers of styrene andt-butyl methacrylate II. Association phenomena in mixtures of block copolymer with polystyrene (1992)
    Springer
    Chromatographia 34 (1992), S. 363-368 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Precipitation chromatography of polymers ; Block copolymers of styrene-butyl methacrylate ; Association phenomena
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Block copolymers of styrene andt-butyl methacrylate can be analysed by methanol/tetrahydrofuran gradients on C18 or phenyl bonded phase columns. On both of these columns, retention increases with styrene content of the samples. At 50°C, the retention of PS or a block copolymer containing 45% styrene was longer on the phenyl than the C18 columns. This indicates the contribution of adsorption to retention on phenyl bonded phase columns. Lowering the temperature from 50 to 30°C caused earlier elution of part of the sample from the phenyl phase. On a C18 phase the same drop in temperature improved the shape of the peak, which also started later than at 50°C. This effect of temperature is generally observed in polymer retention due to an adsorption mechanism, whereas increasing retention with decrease in temperature is characteristic of a precipitation mechanism. The block copolymer investigated contained 15% free polystyrene precursor which could not be separated from the block copolymer under the conditions employed. The addition of 20% PS homopolymer with a molecular weight similar to that of the styrene block in the copolymer showed that the polystyrene eluted together with the block copolymer, whereas the addition of PS homopolymer with a much higher molecular weight caused an extra peak at the expected elution time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02268369
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  • 58
    Digitale Medien
    Digitale Medien
    Multidentate phenyl-bonded phases in high-performance liquid chromatography (1992)
    Springer
    Chromatographia 34 (1992), S. 381-385 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Molecular recognition ; Multidentate phenyl-bonded phases ; PAHs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary New multidentate phenyl-bonded phases (MPBPs) were synthesized and evaluated the chromatographic retention behaviour with polycyclic aromatic hydrocarbons as sample probes in high-performance liquid chromatography. The new MPBPs show different retention characteristics from the previously synthesized MPBP, designated TP. Nevertheless, the results indicate that the retention mechanism is still the same as the TP phase: the size and shape of the solute molecule can be recognized by a cavity-like space formed by the methyl groups and phenyl rings of MPBPs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02268372
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  • 59
    Digitale Medien
    Digitale Medien
    Comparison and evaluation of HIC columns of different hydrophobicity (1992)
    Springer
    Chromatographia 34 (1992), S. 391-397 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Hydrophobic interaction ; Stationary phases ; Salt effect ; Proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Retention and selectivity in hydrophobic interaction chromatography (HIC) depend both on the type of stationary phase and on the mobile phase. In the last few years various high performance packing materials and columns have been introduced for HIC resulting in a range of different retentions and selectivity. We have investigated the effect of the stationary phase on the retention of various proteins. The retention of some solutes of different hydrophobicities were measured on three commercial HIC columns (TSK-Phenyl, Synchropack-Propyl, CAA-HIC) under isocratic conditions using water-methanol mixtures as eluent. The log kw values determined according to the literature were devalues determined according to the literature were dependent on the type and structure of the stationary phase and indicated a much less hydrophobic character for these columns than that obtained for reversed phase columns. Gradient separations were then carried out on a standard protein mixture using ammonium sulfate and sodium citrate to change the gradient time. In order to compare the effect of the stationary phase and the two salts investigated apparent capacity factors (kg) were determined and plotted against the gradient time obtained for the three columns in the two eluent system. It was shown that the type of stationary phase had a significant effect on the retention of proteins. In addition, the effect of the mobile phase composition, i.e. salt type, was considerably different on the various stationary phases. In order to exploit the potential of HIC to modulate selectivity for the separation of proteins, the combined effect of the stationary phase and the type of salt should be taken into account.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02268374
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  • 60
    Digitale Medien
    Digitale Medien
    Chromatographic characteristics of porphyrine ether glycerides (1992)
    Springer
    Chromatographia 34 (1992), S. 431-432 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Thin-layer chromatography ; Porphyrine ether glycerides
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Efficient TLC and HPLC conditions for the separation of a newly synthesized class of compounds, porphyrine ether glycerides, have been established. Supplementary physico-chemical characteristics are given for this group of solutes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02268379
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  • 61
    Digitale Medien
    Digitale Medien
    Integrated FIA/HPLC method for preconcentration and determination of transition metal ions (1992)
    Springer
    Chromatographia 34 (1992), S. 445-449 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Flow injection analysis ; Combined methods ; Transition metal ions ; Aqueous samples
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An automatic method based on the combination of a flow injection (FI) manifold with a liquid chromatograph has been developed for the enrichment and determination of transition metal ions in water samples. Alternatively, the FI configuration can be used as a screening system for the determination of the total concentration of heavy metals. Two-parameter expressions for calibration graphs involving preconcentration time and concentration of the analytes were established for both the FIA and the integrated FIA/HPLC methods. The preconcentration time depends on the concentration level of the analytes in the samples. The method is linear in the range 2–200 ng/ml, with r.s.d. values between 1.5 and 5.0. It has been applied to the determination of copper, lead, zinc, nickel, cobalt, cadmium and manganese in synthetic water samples.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290233
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  • 62
    Digitale Medien
    Digitale Medien
    Comparison of HPLC and solid phase clean-up methods for identification of PCBs in cod-liver oil by HRGC/MS-SIM technique (1992)
    Springer
    Chromatographia 34 (1992), S. 421-430 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Solid phase extraction ; PCBs in cod-liver oil ; GC/MS identification
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A group of non-planar PCBs (IUPAC nos. 28, 52, 101, 118, 138, 153, and 180) was identified in a cod-liver oil product by using high resolution gas chromatography-mass spectrometry (HRGC/MS) in electron impact (EI) and negative chemical ionization (NCI) modes. The cod-liver oil samples were prepared either in a cyano column by high performance liquid chromatography (HPLC) or by a solid phase extraction (SPE) clean-up procedure that included e.g. purified charcoal treatment. The two methods of sample preparation were evaluated on the basis of the detectabilities of the congeners. The GC/MS-SIM method allowed quantitative monitoring of congeners nos. 52, 101, 118, 138, 153, and 180 at low concentration levels. Detection limits were 1.2 pg and 130 fg (m/z 292.00) in EI and NCI modes, respectively. The determination levels in EI and NCI were 1.8 pg and 290 fg in HPLC followed by HRGC/MS and 170 pg and 27 pg in SPE followed by HRGC/MS. The linear range was from 5.0 pg/μl to 1.0 ng/μl and from 1.0 pg/μl to 1.0 ng/μl in EI and NCI modes, respectively. In addition, the co-planar PCBs, PCDDs, and PCDFs were also screened and two of the chlorinated furanes were identified by HRGC/MS-NCI after separation from non-planar PCBs by SPE. In this case the only congeners that could be quantified were 2,3,4,7,8-PCDF and 1,2,3,4,6,7,8-HCDF, the detection limit for them being 740 fg (m/z 351.90) with NCI. SPE allows the separation of the planar and non-planar compounds, but LC separation is more effective for separation of the compounds of interest from the matrix. LC clean-up is easier and faster to perform than SPE clean-up.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02268378
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  • 63
    Digitale Medien
    Digitale Medien
    Separation of stereoisomers of tetramethylcalix[4]arenoctol and derivatives by high-performance liquid chromatography (1992)
    Springer
    Chromatographia 34 (1992), S. 453-456 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Calix[4]arenes ; Host-guest chemistry ; Separation of stereoisomers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A high performance liquid chromatographic procedure on 5 μm RP-18 was developed for the separation of the four possible cis-trans isomers of tetramethyl-calix[4]arenoctol, and of their octaacetates, and their octamethyl ethers.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290235
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  • 64
    Digitale Medien
    Digitale Medien
    HPLC separation of molecular species of intact sphingomyelin, utilizing multivariate design and optimization (1992)
    Springer
    Chromatographia 34 (1992), S. 529-533 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Sphingomyelin ; Molecular species separation ; Experimental design and optimization ; Chemometrics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An improved method has been developed for the separation of molecular species of intact sphingomyelins from natural sources (chicken egg yolk, bovine brain, and bovine milk) by high performance liquid chromatography with light-scattering detection. The method was developed and optimized using a novel multivariate optimization strategy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290247
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  • 65
    Digitale Medien
    Digitale Medien
    High-performance liquid chromatography of carbohydrates in enzymic hydrolysate of waste paper (1992)
    Springer
    Chromatographia 34 (1992), S. 534-536 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Carbohydrates ; Enzymic hydrolysate ; Waste paper
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Waste paper was pretreated with 5M sulfuric acid at 28°C to give a gel-like solution which was then hydrolyzed with cellulase, purified fromTrichoderma viride, to form carbohydrates. The determination of the carbohydrates was accomplished using an aminopropylbonded silica HPLC column and an RI detector. The detection limits were 20 ppm; xylose, glucose, and cellobiose were the major components. Salts from the buffer solution may affect the activity of cellulase. The analysis of carbohydrates can be performed under acid conditions. HPLC analysis of carbohydrates from enzymatic hydrolysis is reliable and successful.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290248
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  • 66
    Digitale Medien
    Digitale Medien
    Descriptions of the larvae of four nearctic species ofEpoicocladius (Diptera: Chironomidae) with a redescription ofEpoicocladius ephemerae (Kieffer) (1992)
    Springer
    Aquatic ecology 26 (1992), S. 145-155 
    Details
    ISSN: 1573-5125
    Schlagwort(e): Chironomidae ; Epoicocladius ; symbiosis ; taxonomy ; Ephemeridae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The larvae of four species ofEpoicocladius from eastern North America are described along with a redescription of the European species,Epoicocladius ephemerae (Kieffer). A key to known 4th instar Nearctic and western PalaearcticEpoicocladius larvae is presented. Previous species descriptions and records of NearcticEpoicocladius spp. are discussed in reference to the larvae described here. Larvae ofEpoicocladius ephemerae (Kieff.), a species described from Europe which is currently synonymized with the NearcticE. flavens, have yet to be collected in North America. This suggests that the synonymy is invalid andE. ephemerae should be considered a legitimate species. A likely candidate to be the larva ofEpoicocladius flavens (Malloch) is suggested. However, until reared adults are obtained, the larva ofE. flavens remains unknown.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02255235
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  • 67
    Digitale Medien
    Digitale Medien
    The larva and habitat ofParakiefferiella nigra Brundin (Diptera: Chironomidae) (1992)
    Springer
    Aquatic ecology 26 (1992), S. 527-531 
    Details
    ISSN: 1573-5125
    Schlagwort(e): palaeolimnology ; Chironomidae ; taxonomy ; larval subfossils
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Collections of adults ofParakiefferiella nigra Brundin indicate that this chironomid occurs widely in arctic and subarctic zones. In addition, it has occasionally been collected in cool temperate and boreal forest lakes of both North America and Europe. Although widely distributed, the larva and its habitat have not previously been described. Identity of the larva ofP. nigra has been established by studying associated reared specimens. The distinctive larva, with reduced second lateral mental teeth, is stenotopic, and on the basis of modern collections appears to be most abundant in cold, oligotrophic lakes. More data is required to establish the range of thermal environments inhabited by the larva. Larval head capsule remains ofP. nigra are common in late-glacial sediments of southwestern British Columbia lakes and provide important evidence for oligotrophic conditions during late-glacial time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02255286
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  • 68
    Digitale Medien
    Digitale Medien
    Photosynthetic characteristics of Dunaliella salina (Chlorophyceae, Dunaliellales) in relation to β-carotene content (1992)
    Springer
    Journal of applied phycology 4 (1992), S. 11-15 
    Details
    ISSN: 1573-5176
    Schlagwort(e): adaptation ; β-carotene ; Dunaliella salina ; photosynthesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Photosynthetic characteristics of Dunaliella salina with high (red form) and low β-carotene (green form) concentrations were studied. D. salina growing in brine saltworks exhibited a high level of β-carotene (15 pg cell−1). The rate of oxygen evolution as a function of irradiance was higher in the red than in the green form (on chlorophyll basis). Photosynthetic inhibition of the green form was observed above 500 µmol m−2 s−1. The red form appeared more resistant to high irradiance and no inhibition in O2 evolution was observed up 2000 µmol m−2 s−1. However, when these results are expressed on a cell number basis the rate of oxygen evolution was significantly higher in the green form. Carbonic anhydrase (CA) activity (total, soluble, membrane bound) was found in red and green forms. CA was higher in the red form on a chlorophyll basis, but lower if expressed on a protein basis. The light dependent rate of oxygen evolution and photoinhibition depends on the concentration of β-carotene in D. salina cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00003955
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  • 69
    Digitale Medien
    Digitale Medien
    Performance of a flat plate, air-lift reactor for the growth of high biomass algal cultures (1992)
    Springer
    Journal of applied phycology 4 (1992), S. 1-9 
    Details
    ISSN: 1573-5176
    Schlagwort(e): photobioreactor ; flat plate air-lift reactor ; Chlorella ; Synechococcus ; hydraulic characteristics ; photosynthesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A flat plate, multi-pass air lift reactor (FPALR) for the culture of photosynthetic organisms was constructed from twin wall acrylic sheet and its performance characterised. When operated at an air input of 2.01 min−1 the multi-pass system had a Reynolds number of 5200 indicating fully turbulent flow. Chlorella vulgaris 211/11c was found to have a stationary phase biomass of 1.48 g 1−1 when grown in the flat plate air lift reactor (FPALR) at 100 µmol m−2s−1 compared to 1.11 g 1−1 when cultured in the continually stirred tank reactor (CSTR) at the same PFD (photon flux density). The same organism cultured at 200 µmol m−2s−1 achieved a stationary phase biomass of 1.71 g 1−1 in the FPALR. In contrast, Scenedesmus sp. produced a stationary phase biomass of 2.27 g1−1 and 1.27 g1−1, when cultured at 100 µmol m−2s−1 in the FPALR and the CSTR respectively. The growth rates of both organisms were also higher in the PFALR.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00003954
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  • 70
    Digitale Medien
    Digitale Medien
    Phylogenetic definitions and taxonomic philosophy (1992)
    Springer
    Biology and philosophy 7 (1992), S. 295-313 
    Details
    ISSN: 1572-8404
    Schlagwort(e): Clade ; class ; composite whole ; definition ; defining property ; essentialism ; evolution ; individual ; intension ; name ; ostensive definition ; phylogeny ; population ; set ; species ; taxon ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Philosophie
    Notizen: Abstract An examination of the post-Darwinian history of biological taxonomy reveals an implicit assumption that the definitions of taxon names consist of lists of organismal traits. That assumption represents a failure to grant the concept of evolution a central role in taxonomy, and it causes conflicts between traditional methods of defining taxon names and evolutionary concepts of taxa. Phylogenetic definitions of taxon names (de Queiroz and Gauthier 1990) grant the concept of common ancestry a central role in the definitions of taxon names and thus constitute an important step in the development of phylogenetic taxonomy. By treating phylogenetic relationships rather than organismal traits as necessary and sufficient properties, phylogenetic definitions remove conflicts between the definitions of taxon names and evolutionary concepts of taxa. The general method of definition represented by phylogenetic definitions of clade names can be applied to the names of other kinds of composite wholes, including populations and biological species. That the names of individuals (composite wholes) can be defined in terms of necessary and sufficient properties provides the foundation for a synthesis of seemingly incompatible positions held by contemporary individualists and essentialists concerning the nature of taxa and the definitions of taxon names.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00129972
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  • 71
    Digitale Medien
    Digitale Medien
    Polypedilum digitifer Townes andPolypedilum griseopunctatum (Malloch) (Diptera, Chironomidae): Redescription of adult males with a description and separation of the immature stages (1992)
    Springer
    Aquatic ecology 26 (1992), S. 203-213 
    Details
    ISSN: 1573-5125
    Schlagwort(e): aquatic insects ; midges ; chironomidae ; taxonomy ; Diptera
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Polypedilum (Tripodura) digitifer Townes andPolypedilum (Tripodura) griseopunctatum (Malloch) are morphologically similar species of Chironomidae. Using associated material from New York State, the adult males for both species are redescribed (adding previously ignored characters) and the mature larva and pupa are thoroughly described for the first time. Traits for distinguishing these species from each other and possibly from other Nearctic species ofPolypedilum (Tripodura) are provided.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02255243
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  • 72
    Digitale Medien
    Digitale Medien
    Corrections to the Chironomidae part of the Catalogue of Palaearctic Diptera (1992)
    Springer
    Aquatic ecology 26 (1992), S. 215-221 
    Details
    ISSN: 1573-5125
    Schlagwort(e): taxonomy ; palaearctic Chironomidae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract An extensive list of corrections to the Chironomidae part of the ‘Catalogue of Palaearctic Diptera’ (ASHE and CRANSTON, 1990) is given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02255244
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  • 73
    Digitale Medien
    Digitale Medien
    Nothobartsia, a new genus ofScrophulariaceae from southwest Europe (1992)
    Springer
    Plant systematics and evolution 179 (1992), S. 59-71 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Angiosperms ; Scrophulariaceae ; Rhinanthoideae ; Rhinantheae—Euphrasinae ; Nothobartsia aspera ; N. spicata ; Bartsia ; Odontites ; Euphrasia ; Cladistics ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Recent systematic studies ofBartsia andOdontites showed the necessity to exclude the closely related perennial speciesBartsia aspera (Portugal and northern Morocco) andBartsia spicata (Central Pyrenees) from the genusBartsia as a segregate genus namedNothobartsia. Morphologically this new genus combines characteristic features ofBartsia and ofOdontites. Its autonomous systematic position is supported by the cladistic analysis, showing thatNothobartsia represents a relatively primitive genus standing close to the common ancestral root ofBartsia, Euphrasia, andOdontites.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00938019
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  • 74
    Digitale Medien
    Digitale Medien
    A reappraisal ofPelargonium sect.Ligularia (Geraniaceae) (1992)
    Springer
    Plant systematics and evolution 179 (1992), S. 257-276 
    Details
    ISSN: 1615-6110
    Schlagwort(e): Angiosperms ; Geraniaceae ; Pelargonium ; Chromosome numbers ; karyotypes ; hybridization ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A study of 33 species ofPelargonium sect.Ligularia reveals four basic chromosome numbers, x = 8, 9, 10, and 11, and variation in chromosome size. From evidence of karyology and hybridization attempts, proposals are made to divide the section into smaller groups and to transfer some species to other sections.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00937601
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  • 75
    Digitale Medien
    Digitale Medien
    Identification of Vigna spp. through specific seed storage polypeptides (1992)
    Springer
    Euphytica 62 (1992), S. 39-43 
    Details
    ISSN: 1573-5060
    Schlagwort(e): Vigna spp. ; identification ; specific bands ; globulins ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Seed globulins of ten Vigna species were separated by means of SDS electrophoresis. Both inter and intraspecific variation were observed. Groups of specific bands which do not vary in the species being present in all the accessions of the species were identified. These species-specific bands, allow the identification of the 10 Vigna spp. analyzed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00036085
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  • 76
    Digitale Medien
    Digitale Medien
    pH dependent chlorophyll fluorescence quenching in spinach thylakoids from light treated or dark adapted leaves (1992)
    Springer
    Photosynthesis research 31 (1992), S. 11-19 
    Details
    ISSN: 1573-5079
    Schlagwort(e): carotenoid ; chlorophyll fluorescence ; non-photochemical quenching ; pH ; photosynthesis ; zeaxanthin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The pH dependence of maximum chlorophyll fluorescence yield (Fm) was examined in spinach thylakoids in the presence of nigericin to dissipate the transthylakoid pH gradient. 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea (DCMU) was present to eliminate photochemical quenching. Thylakoids were prepared from dark adapted leaves (‘dark’ thylakoids) or preilluminated leaves (‘light’ thylakoids). In the latter there had been approximately 50% conversion of the xanthophyll violaxanthin to zeaxanthin, while no conversion had occurred in the former. In the presence of a reductant such as ascorbate, antimycin A sensitive quenching was observed (half maximal quenching at 5 μM), whose pH dependence differed between the two types of thylakoid. Preillumination of leaves resulted in more quenching at pH values where very little quenching was observed in ‘dark’ thylakoids (pH 5–7.6). This was similar to activation of high-energy-state quenching (qE) observed previously (Rees D, Young A, Noctor G, Britton G and Horton P (1989) FEBS Lett 256: 85–90). Thylakoids isolated from preilluminated DTT treated leaves, that contained no zeaxanthin, behaved like dark thylakoids. A second form of quenching was observed in the presence of ferricyanide, that could be reversed by the addition of ascorbate. This was not antimycin A sensitive and showed the same pH dependence in both types of thylakoid. The former type of quenching, but not the latter, showed similar low temperature fluorescence emission spectra to qE, and was considered to occur by the same mechanism.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00049532
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  • 77
    Digitale Medien
    Digitale Medien
    Light, iron, Sam Granick and the origin of life (1992)
    Springer
    Photosynthesis research 33 (1992), S. 163-170 
    Details
    ISSN: 1573-5079
    Schlagwort(e): biosynthetic pathway ; evolution ; free energy ; photochemistry ; photosynthesis ; porphyrin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Living matter is an organized system which requires a continual flux of energy for its survival. As a working assumption, the flux of energy required for the origin of a self-duplicating cell is taken as the power required for the maintenance of a modern cell: 10 mW per g of carbon or some 105 times the output per gram of the sun. Solar photochemistry supplies the energy for the continuing evolution of life and, by continuity, for its origin. The iron oxide-sulfide photosynthetic unit proposed by S. Granick 35 years ago was meant to supply this energy. The evolution of complex organic photosensitizers is rationalized by the Granick hypothesis that biosynthetic pathways recapitulate their evolution. These concepts are discussed in the context of the evolution of photosynthetic systems and the known properties of these pigments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00039178
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  • 78
    Digitale Medien
    Digitale Medien
    Cultivar differences in leaf photosynthesis of rice bred in Japan (1992)
    Springer
    Photosynthesis research 32 (1992), S. 139-146 
    Details
    ISSN: 1573-5079
    Schlagwort(e): leaf senescence ; mesophyll conductance ; Oryza sativa L. ; photosynthesis ; specific leaf weight ; stomatal conductance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The grain yield of rice (Oryza sativa L.), as well as of other cereal crops, is limited to a large extent, by the supply of photosynthates produced during grain filling period. In this study, flag leaf photosynthesis (LPS) after heading was compared among 32 cultivars bred during the past century in Japan, to determine if the improvement of LPS has occurred with the breeding advance of high yielding cultivars. Measurement of LPS was made for 5 consecutive years in the paddy field, on the flag leaf of the main stem, at heading (LPS-0), and 2 weeks (LPS-2) and 4 weeks (LPS-4) after heading. LPS decreased with advance of leaf senescence from LPS-0 to LPS-2, and then to LPS-4. However, if nitrogen was top-dressed at the heading time, high LPS-2 was maintained, particularly in the newer cultivars. A significant positive correlation between LPS and the released year of cultivar was found at LPS-2, especially in the nitrogen top-dressed plot, but not at LPS-0 or LPS-4. Cultivar difference in LPS of the senescing leaves were not stable through the different years, whereas LPS-0 was stable over years, suggesting that the LPS in the senescent leaf is susceptible to the environmental variation due to the effects on leaf senescence. Cultivar difference in LPS at any stage was closely associated with mesophyll conductance to CO2, and stomatal conductance was also associated with cultivar difference in such a high LPS as LPS-0 and nitrogen top-dressed LPS-2. Significant correlation between LPS and specific leaf weight was not observed at any stage of the flag leaf.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00035948
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  • 79
    Digitale Medien
    Digitale Medien
    Mechanisms for controlling balance between light input and utilisation in the salt tolerant alga Dunaliella C9AA (1992)
    Springer
    Photosynthesis research 32 (1992), S. 181-191 
    Details
    ISSN: 1573-5079
    Schlagwort(e): chlorophyll fluorescence ; Dunaliella ; photosynthesis ; quantum efficiency
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The yield of photosynthetic O2 evolution was measured in cultures of Dunaliella C9AA over a range of light intensities, and a range of low temperatures at constant light intensity. Changes in the rate of charge separation at Photosystem I (PS I) and Photosystem II (PS II) were estimated by the parameters ΦPS I and ΦPS II . ΦPS I is calculated on the basis of the proportion of centres in the correct redox state for charge separation to occur, as measured spectrophotometrically. ΦPS II is calculated using chlorophyll fluorescence to estimate the proportion of centres in the correct redox state, and also to estimate limitations in excitation delivery to reaction centres. With both increasing light intensity and decreasing temperature it was found that O2 evolution decreased more than predicted by either ΦPS I or ΦPS II. The results are interpreted as evidence of non-assimilatory electron flow; either linear whole chain, or cyclic around each photosystem.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00034794
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  • 80
    Digitale Medien
    Digitale Medien
    Conjectures and reveries (1992)
    Springer
    Photosynthesis research 33 (1992), S. 171-176 
    Details
    ISSN: 1573-5079
    Schlagwort(e): photosynthesis ; origin of life ; clays
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The origin of photosynthesis is speculated to have involved carbon dioxide and self-replicating iron-rich clays. The later evolution of photosynthesis is considered to have undergone four distinct phases: (1) The photoreduction of carbon dioxide by ferrous ion to form oxalate and formate. (2) The entry of sulfur into the evolving clay system which led to the formation of acetyl thioesters. The polymerization of the acetyl thioeters led to the formation of quinones. The formation of Fe2S2 and Fe4S4 cores appeared in this phase. (3) The ability to fix nitrogen characterized the third phase. This led to the formation of pyrrole, flavin, nicotinamide, phycobilins, porphyrins and chlorophyll. (4) Finally, phosphate entered the evolving system. The chromophores evolved from ferrous ion through the quinones, carotenoids, phycobilins to chlorophyll. This evolution of chromophores implies that photosynthesis began in the UV and evolved through the blue, yellow, orange into the red. The electron transport chain evolved from ferrous ion through the Fe2S2 and Fe4S4 cores to the hemes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00039179
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  • 81
    Digitale Medien
    Digitale Medien
    Changes in Photosystem II fluorescence in Chlamydomonas reinhardtii exposed to increasing levels of irradiance in relationship to the photosynthetic response to light (1992)
    Springer
    Photosynthesis research 31 (1992), S. 31-40 
    Details
    ISSN: 1573-5079
    Schlagwort(e): Chlamydomonas ; convexity ; chlorophyll a fluorescence ; Photosystem II heterogeneity ; photoinhibition ; photosynthesis ; PS II repair cycle
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effects of a 60 min exposure to photosynthetic photon flux densities ranging from 300 to 2200 μmol m−2s−1 on the photosynthetic light response curve and on PS II heterogeneity as reflected in chlorophyll a fluorescence were investigated using the unicellular green alga Chlamydomonas reinhardtii. It was established that exposure to high light acts at three different regulatory or inhibitory levels; 1) regulation occurs from 300 to 780 μmol m−2s−1 where total amount of PS II centers and the shape of the light response curve is not significantly changed, 2) a first photoinhibitory range above 780 up to 1600 μmol m−2s−1 where a progressive inhibition of the quantum yield and the rate of bending (convexity) of the light response curve can be related to the loss of QB-reducing centers and 3) a second photoinhibitory range above 1600 μmol m−2s−1 where the rate of light saturated photosynthesis also decreases and convexity reaches zero. This was related to a particularly large decrease in PS IIα centers and a large increase in spill-over in energy to PS I.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00049534
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  • 82
    Digitale Medien
    Digitale Medien
    Species-related differences in the electrophoretic behavior of CP 29 and CP 26: An immunochemical analysis (1992)
    Springer
    Photosynthesis research 34 (1992), S. 249-262 
    Details
    ISSN: 1573-5079
    Schlagwort(e): photosynthesis ; light-harvesting chlorophyll-protein complex ; spinach ; maize
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The monomeric chlorophyll-protein complexes, CP 29 and CP 26 seen in the Camm and Green (1980) and Dunahay and Staehelin (1986) green gels do not always migrate in the order of the apparent molecular weight of their apoproteins as determined by denaturing gel electrophoresis. In barley and corn they do, but in spinach they do not. In addition, in some higher plant species these chlorophyll-protein complexes comigrate on green gels causing confusion in the literature. To remedy this situation and circumvent future confusion, we propose that the CP 29 and CP 26 complexes be named according to the relative molecular weight of their apoproteins on denaturing gels. Our proposal is supported by the results obtained from four antibodies used on Western blot samples of whole thylakoids, grana membranes, and PS II preparations from different plants. The higher molecular weight proteins (proposed CP 29's) react strongly to one set of antibodies, and the lower molecular weight proteins (proposed CP 26's) react strongly to a different set. In spinach, CP 26 antibodies react also with CP 29, but the extent of the cross-reactivity depends critically on the gel electrophoresis system used. Accordingly, a lack of antibody reactivity under certain conditions may not indicate two proteins are unrelated, just simply that a particular epitope is no longer accessible following gel electrophoresis with a particular buffer system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00033442
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  • 83
    Digitale Medien
    Digitale Medien
    Concerning oscillations (1992)
    Springer
    Photosynthesis research 34 (1992), S. 387-395 
    Details
    ISSN: 1573-5079
    Schlagwort(e): oscillations ; photosynthesis ; regulation ; phosphate ; down-stream
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00029813
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  • 84
    Digitale Medien
    Digitale Medien
    Chloroplast energization and oxidation of P700/plastocyanin in illuminated leaves at reduced levels of CO2 or oxygen (1992)
    Springer
    Photosynthesis research 34 (1992), S. 433-447 
    Details
    ISSN: 1573-5079
    Schlagwort(e): chlorophyll fluorescence ; cyclic electron transport ; photorespiration ; photosynthesis ; Photosystem II ; proton gradient
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Chlorophyll fluorescence, light scattering, the electrochromic shift P515 and levels of some photosynthetic intermediates were measured in illuminated leaves. Oxygen and CO2 concentrations in the gas phase were varied in order to obtain information on control of Photosystem II activity under conditions such as produced by water stress, when stomatal closure restricts access of CO2 to the photosynthetic apparatus. Light scattering and energy-dependent fluorescence quenching indicated a high level of chloroplast energization under high intensity illumination even when linear electron transport was curtailed in CO2-free air or in 1% oxygen with 35 μll-1 CO2. Calculations of the phosphorylation potential based on measurements of phosphoglycerate, dihydroxyacetone phosphate and NADP revealed ratios of intrathylakoid to extrathylakoid proton concentrations, which were only somewhat higher in air containing 35 μl l-1 CO2 than in CO2-free air or 1% oxygen/35 μl l-1 CO2. Anaerobic conditions prevented appreciable chloroplast energization. Acceptor-limitation of electron flow resulted in a high reduction level of the electron transport chain, which is characterized by decreased oxidation of P700, not only under anaerobic conditions, but also in air, when CO2 was absent, and in 1% oxygen, when the CO2 concentration was reduced to 35 μll-1. Efficient control of electron transport was indicated by the photoaccumulation of P700 + at or close to the CO2 compensation point in air. It is proposed to require the interplay between photorespiratory and photosynthetic electron flows, electron flow to oxygen and cyclic electron flow. The field-indicating electrochromic shift (P515) measured as a rapid absorption decrease on switching the light off followed closely the extent of photoaccumulation of P700 + in the light.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00029817
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  • 85
    Digitale Medien
    Digitale Medien
    A new species of Ilyocryptus (Anomopoda: Macrothricidae) from Argentina (1992)
    Springer
    Hydrobiologia 231 (1992), S. 141-151 
    Details
    ISSN: 1573-5117
    Schlagwort(e): Cladocera ; Anomopoda ; new species ; taxonomy ; Neotropis ; Argentina
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract I. elegans n.sp. from the Parana River, northeastern Argentina is proposed and its morphological features are compared with those of the apparently related I. agilis. Its outstanding characteristics are the long 2rd to 5th setae of ventral margin of the valves, the rudimentary nature of defensive setae, the low number of spines in the preanal lobe of postabdomen and the unequality of the length of the setae in the outer distal lobe of first trunk limbs. Finding of this new species suggests that I. agilis would be a complex of species and its records should be revised.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00018198
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  • 86
    Digitale Medien
    Digitale Medien
    Dynamic versus static models for photosynthesis (1992)
    Springer
    Hydrobiologia 238 (1992), S. 189-196 
    Details
    ISSN: 1573-5117
    Schlagwort(e): photosynthesis ; phytoplankton ; time scales ; environmental variability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Static P(I) curves relating photosynthesis to the instantaneous light might not be adequate to describe the activity of algal cells in lakes or oceans where mixing can cause a complex pattern of light variation. In recent years experimental results have provided evidence that, subsequent to changes in light, the rate of photosynthesis may be delayed or exhibit complex temporal dynamics. The model DYPHORA (DYnamic model for the PHOtosynthetic Rate of Algae) takes these dynamics into account by introducing two characteristic response times for the biological processes: (1) the effect of light inhibition having a time scale of minutes to a few hours and (2) the time lag of the rate of photosynthesis for increasing light intensities having a time scale of seconds to minutes. The importance of the dynamic relative to the static description of photosynthesis depends on the time scales of the changes in the environment and the biological response, becoming significant when the time scales are comparable.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00048788
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  • 87
    Digitale Medien
    Digitale Medien
    Effects of clay discharges on streams (1992)
    Springer
    Hydrobiologia 248 (1992), S. 215-234 
    Details
    ISSN: 1573-5117
    Schlagwort(e): suspended solids ; turbidity ; algae ; photosynthesis ; light ; mining
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Placer gold-mining on the West Coast of the South Island of New Zealand provided a field test-bed for investigating the impacts of fine inorganic suspensoids (clays) on streams not subjected to other abuses. The suspensions of clays (40% between 0.55 and 1 µm in diameter) seeping into the streams from gold mines were colloidally stable. The clay particles attenuated light in the streamwater with near maximum efficiency leading to severe degradation of stream optical quality. Turbidity increased from a median of 2.4 NTU upstream often to 〉 100 NTU (median 15 NTU) downstream. The stream waters, which were strongly-coloured by humic substances, were changed from a dark organge colour to a bright ‘muddy’ appearance downstream of mining, and visual clarity was reduced from a few metres to as low as 0.03 m (median 0.33 m). The clay discharges decreased light penetration into the stream water such that irradiance averaged over a 12 hr photoperiod at the bed (typically about 0.3 m depth in runs at baseflow) fell from about 340 µE m−2 s−1 upstream to as low as 80 µE m−2 s−1 (median 190 µE m−2 s−1) at matched downstream sites. This reduction in light proportionally reduced benthic primary productivity downstream of the mining activity. In turn this reduced benthic algal biomass and lowered the phototrophic content of the epilithon. In spite of their extremely low settling velocities (〈 1 µm s−1) some clay particles were deposited on the stream bed owing to entrapment in the epilithon matrix. This decreased the organic content of the epilithon (from an average of 19% upstream to 8.5% downstream) so reducing its quality as food for invertebrate animals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00006149
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  • 88
    Digitale Medien
    Digitale Medien
    Alona sketi sp.n. (Cladocera:Chydoridae), the second cave-inhabiting Cladoceran from former Yugoslavia (1992)
    Springer
    Hydrobiologia 248 (1992), S. 105-114 
    Details
    ISSN: 1573-5117
    Schlagwort(e): Cladocera ; Chydoridae ; taxonomy ; hypogean waters ; Yugoslavia ; Slovenia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Alona sketi sp.n. is the second blind cave-dwelling cladoceran from Yugoslavia. It has been found only in some lakelets in a cave in the SW Slovenia (Yugoslavia). The new taxon is related to A. hercegovinae Brancelj, 1990 from Hercegovina, but both differ markedly. The stygobiotic nature of the new taxon is supported by a reduced and depigmented eye apparatus, no signs of malnutrition in a habitat poor in organic material, trunk limbs with modified setae and scrapers to increase ability for food gathering, and an exclusively stygobiotic accompanying fauna.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00006078
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  • 89
    Digitale Medien
    Digitale Medien
    Photosynthetic performance of deep-water macroalgae (Phaeophyta, Dictyotales) off Bermuda (1992)
    Springer
    Hydrobiologia 231 (1992), S. 93-98 
    Details
    ISSN: 1573-5117
    Schlagwort(e): photosynthesis ; macroalgae ; deep-water ; Bermuda ; Dictyotales
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Photosynthetic performance and dark respiration rates were determined in situ for abundant macroalgae occurring between 27–49 m depths off Bermuda. Brown algae, particularly members of the order Dictyotales, predominated at all deep-water sites, and Stypopodium zonale was the most abundant species. Species showed net photosynthesis at very low ambient irradiances (〈0.01 maximum Io). Lobophora variegata, a species with a highly decumbent growth form, had low productivity across all irradiances. In contrast, Dictyota spp. (D. bartayresii, D. dichotoma, D. divaricata) and S. zonale had high photosynthetic capacity (ca. 400 µmol O2 gdw−1 h−1), and light saturation was not evidenced at the highest ambient irradiance level (300 µE m−1 s−1) for species with thin, flat thalli. Light-harvesting pigment concentrations reflected tissue-nitrogen levels. C:N atom ratios, except for L. variegata and D. divaricata, were within the ratio for balanced growth. The repeated occurrence and photosynthetic efficiency of these Dictyotalean species in subtropical and tropical deep-water habitats emphasize their successful adaptation to low-light, nutrient-poor environments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00006501
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  • 90
    Digitale Medien
    Digitale Medien
    The unique headpore of Monospilus dispar (Cladocera, Chydoridae) is not lonesome: new record of minute lateral pores (1992)
    Springer
    Hydrobiologia 232 (1992), S. 145-148 
    Details
    ISSN: 1573-5117
    Schlagwort(e): headshield ; phylogeny ; SEM ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The headshield of Monospilus dispar (Cladocera, Chydoridae, Aloninae) was characterized by the presence of a unique headpore. Scanning Electron Microscopy shows the occurrence of minute pores close to the main headpore. The intimate structure of the main headpore is formed by concentric lamellae. This new information leads to new considerations about phylogeny.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00017473
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  • 91
    Digitale Medien
    Digitale Medien
    Differentiation of North American and European forms of Fredericella sultana (Blumenbach) (Ectoprocta: Phylactolaemata) (1992)
    Springer
    Hydrobiologia 237 (1992), S. 185-193 
    Details
    ISSN: 1573-5117
    Schlagwort(e): Bryozoa ; Ectoprocta ; Phylactolaemata ; Fredericella ; taxonomy ; karyotype ; genetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Fredericella sultana (Blumenbach, 1779) has long been considered one of the few freshwater bryozoan species with a truly cosmopolitan distribution. However, chromosome spreads from European material show 2n = 16 compared to 2n = 14 in North American specimens. In laboratory rearing the two forms are morphologically indistinguishable except for the surface texture of their statoblasts. Smooth statoblasts of European colonies match early illustrations of the species, while the densely pitted statoblasts of the North American form resemble those of F. indica Annandale 1909. On the basis of these observations we tentatively designate the North American ‘F. sultana’ as F. indica. The only known American species with smooth statoblasts is F. australiensis Goddard 1909, in which the 2n = 16 karyotype is similar or identical to European F. sultana; however, despite this karyotypic similarity the two species retain their distinguishing morphology when reared together in the laboratory. Two enzymes from a single specimen of European F. sultana were electrophoretically distinct from the corresponding enzymes present in samples of both F. australiensis and North American ‘F. sultana’. Four phosphoglucose isomerase alleles were present in North American ‘F. aultana’ from four geographically separated collection sites, although only one genotype for this locus was observed in material from any one site. These genetic findings are consistent with a relatively short-range dispersal potential in this species as compared to Plumatella species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00005850
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  • 92
    Digitale Medien
    Digitale Medien
    Diel periodicity in phytoplankton productivity (1992)
    Springer
    Hydrobiologia 238 (1992), S. 1-35 
    Details
    ISSN: 1573-5117
    Schlagwort(e): periodicity ; diel ; circadian ; clocks ; photosynthesis ; phytoplankton
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Daily variation in phytoplankton productivity influences the dynamics and linkages between several large scale processes in aquatic ecosystems. As part of an opening address to the 5th International workshop for the Group for Aquatic Productivity (GAP), the daily patterns of variability in photosynthesis for different algal classes was introduced and accompanied by a discussion of the sources of environmental and endogenous regulation of repeating biological oscillations that occur in phytoplankton on timescales of one day. It is suggested that one way to develop a database that serves to sort and predict phytoplankton variability over the day may be to encourage the creation of a ‘temporal library’. Such a library would be comprised of temporally fixed maps of circadian clock-controlled rhythms for individual species, as well as temporally variable maps of diel periodicities that only can be defined for a selected set of environmental conditions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00048771
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  • 93
    Digitale Medien
    Digitale Medien
    High biomass and production of picoplankton in a Chinese integrated fish culture pond (1992)
    Springer
    Hydrobiologia 237 (1992), S. 15-23 
    Details
    ISSN: 1573-5117
    Schlagwort(e): picoplankton ; photosynthesis ; primary production ; cyprinids ; fish farm pond
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The phytoplankton dynamics of a Chinese integrated fish culture pond in the suburbs of Shanghai were studied in September and October 1989. The chlorophyll a concentration was high with a range of 62.5–127.3 µg l−1; however, daily net production of phytoplankton was relatively low, with a range of 0.53–1.94 gC m −2 d−1. Of the total phytoplankton biomass, 70–87% was composed of nanoplankton (〈10 µm) and picoplankton, probably because of the selective feeding by phytoplanktivorous carp. In particular, the chlorophyll a concentration of picoplankton was 2.1 – 14.1 mg m −3, and its contribution to total phytoplankton production rate was high (18–68%).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00008423
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  • 94
    Digitale Medien
    Digitale Medien
    Freshwater snails of East Caprivi and the lower Okavango River Basin in Namibia and Botswana (1992)
    Springer
    Hydrobiologia 246 (1992), S. 9-40 
    Details
    ISSN: 1573-5117
    Schlagwort(e): Mollusca ; Gastropoda ; freshwater snails ; taxonomy ; distribution ; Africa ; Namibia ; Botswana ; Okavango River
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A systematic account is given of the aquatic gastropod fauna of the lower Okavango River in Namibia and Botswana, and of the East Caprivi area in Namibia, based on collections made mostly in 1983–86 from about 100 different sites. A total of 20 living species are reported, 9 of them for the first time from this area: Bellamya monardi, Lobogenes michaelis, Cleopatra elata, Afrogyrus coretus, Segmentorbis angustus, S. kanisaensis, Bulinus scalaris, B. depressus and B. tropicus. All are found outside this area and most are widely distributed Afrotropical species. Some do not occur farther south than the Okavango Delta, while others reach a south-western limit here but occur at greater latitude in the eastern tropical corridor on the coast of Natal. Bulinus globosus and Biomphalaria pfeifferi occur throughout the study area and are intermediate hosts for schistosome parasites of man and livestock.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00005620
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  • 95
    Digitale Medien
    Digitale Medien
    Photosynthetic activity of phytoplankton in a high altitude lake (Emerald Lake, Sierra Nevada, California) (1992)
    Springer
    Hydrobiologia 230 (1992), S. 37-48 
    Details
    ISSN: 1573-5117
    Schlagwort(e): photosynthesis ; alpine lake ; phytoplankton
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Photosynthetic activity by phytoplankton was measured during the ice-free seasons of 1984, 1985 and 1987 using the 14C radioassay in high altitude Emerald Lake (California). Relative quantum yield (αB) and light-saturated chlorophyll-specific carbon uptake (Pm B) were calculated from the relationship of light and photosynthesis fitted to a hyperbolic tangent function. Temporal changes in Pm B showed no regular pattern. Seasonal patterns of αB generally had peaks in the summer and autumn. Phytoplankton biomass (as measured by chlorophyll a) and light-saturated carbon uptake (Pm) had peaks in the summer and autumn which were associated with vertical mixing. Estimates of mean daily carbon production were similar among the three years: 57 mg C m−2 2 d−1 in 1984, 70 mg C m−2 2 d−1 in 1985 and 60 mg C m−2 d−1 in 1987. Primary productivity in Emerald Lake is low compared to other montane lakes of California and similar to high-altitude or high-latitude lakes in other regions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00015113
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  • 96
    Digitale Medien
    Digitale Medien
    An analysis of recent taxonomic concepts in wild potatoes (Solarium sect. Petota) (1992)
    Springer
    Genetic resources and crop evolution 39 (1992), S. 23-37 
    Details
    ISSN: 1573-5109
    Schlagwort(e): germplasm ; potato ; Solanum sect. Petota ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Solanum L. sect. Petota Dumort., the potato and its wild relatives, contains 232 species, according to the latest taxonomic interpretation of Hawkes (1990). Section Petota is distributed in the Americas from the southwestern United States to southern Chile. This economically important group has attracted the attention of numerous taxonomists with various taxonomic philosophies. There are 531 validly published basionyms in the group, plus 67 nomina nuda or nomina dubia, and subsequent transfers to other ranks raise the number of names to 664. The taxonomy of sect. Petota has been dominated in recent years by J. G. Hawkes & J. P. Hjerting (co-workers) and C. M. Ochoa. The near simultaneous and independent publication of three recent books by these workers, treating the Bolivian species of sect. Petota, provides a novel opportunity to compare their taxonomic philosophies. Additionally, a recent independent treatment of all of the South American species by L. E. Gorbatenko provides a new interpretation of affiliations of species to series that is compared to the recent treatment of Hawkes and earlier treatments of S. M. Bukasov and D. S. Correll. These treatments differ in the placement of species into series, species boundaries, rank of infraspecific taxa, and hypotheses of hybridization. Our analysis illustrates the wide differences of taxonomic interpretation possible when independent workers treat the same material. The comparison provides insights into unresolved taxonomic questions in sect. Petota and indicates the need for a practical taxonomic resolution that will benefit plant breeders and other researchers on wild potatoes. Reasons for the discrepancies are discussed and suggestions for future research are provided.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00052651
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  • 97
    Digitale Medien
    Digitale Medien
    Influence of medium frequency light/dark cycles of equal duration on the photosynthesis and respiration of Chlorella pyrenoidosa (1992)
    Springer
    Hydrobiologia 238 (1992), S. 53-62 
    Details
    ISSN: 1573-5117
    Schlagwort(e): light/dark cycles ; photosynthesis ; Chlorella ; diurnal variations ; respiration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Chlorella pyrenoidosa was grown in three continuous cultures each receiving a different light regime during the light period of a diurnal cycle. Hourly samples taken during the light period were subjected to medium frequency light/dark oscillations of equal duration, ranging from 3 to 240 seconds. The oxygen consumption and production of each sample were measured with an oxygen electrode in a small oxygen chamber. Although the light/dark cycles had little overall influence on photosynthetic activity, the microalgae appeared to adapt to the light regime to which they were subjected. Large differences were found between the maximum chlorophyll-specific production rates (P infmax supB ), the chlorophyll-specific production rates (PB) and the respiration rates between the cultures and treated subsamples. Respiration rates increased during the light period, whilst PB either increased, or had a mid light period minimum or maximum. The culture which received an hourly light oscillation during the light period had the highest P infmax supB and lowest respiration rates, and it is suggested that these algae react as in nature, whereas either a sinusoidal or a block light pattern is ‘unnatural’. The latter light regime is commonly used in laboratory studies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00048773
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  • 98
    Digitale Medien
    Digitale Medien
    The effect of dynamic light regimes on Chlorella II. Minimum quantum requirement and photosynthesis-irradiance parameters (1992)
    Springer
    Hydrobiologia 238 (1992), S. 79-88 
    Details
    ISSN: 1573-5117
    Schlagwort(e): dynamic light regime ; photosynthesis ; respiration ; quantum requirement
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Comparisons were made of photosynthesis in three light limited cyclostat cultures (LD = 8:16, dilution rate 0.7 d−1) of Chlorella pyrenoidosa, differing only in the dynamics of irradiance supply: as a constant rate, i.e. a block culture; as a sine function of the light period, i.e. a sinusoidal culture; as an 8 h sine function superimposed by an 1 h sine function, i.e. an oscillating culture. The sinusoidal culture had a constant minimum quantum requirement for oxygen evolution (QR) of 10.8 over the photoperiod. The OR of the oscillating culture increased from 24 to 37 during the photoperiod. From changes in α and P max we suggest that: (1) photosynthetic units (PSU) of the block and sinusoidal sulture increased in number; (2) increasingly fewer chlorophyll molecules participated in oxygenic photosynthesis with a decreasing turnover time of the PSU's during an oscillating photoperiod. Values of I k decreased slightly in the block culture, increased slightly in the sinusoidal culture and showed a twofold increase in the oscillating culture. From the ratio of in situ oxygen production (qO2) and P max we infer a balanced equilibrium between photosystem activity and electron transport capacity for the block and sinusoidal culture. We hypothesize that the qO2 values of the oscillating culture underestimated true oxygen production rates due to a nonlinear response at peak light intensities. The results show that a dynamical photoperiod provoked significantly different photosynthetic responses, even though the overall growth rate was unaffected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00048776
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  • 99
    Digitale Medien
    Digitale Medien
    Epilithic chlorophyll a, photosynthesis, and respiration in control and fertilized reaches of a tundra stream (1992)
    Springer
    Hydrobiologia 240 (1992), S. 121-131 
    Details
    ISSN: 1573-5117
    Schlagwort(e): streams ; arctic ; tundra ; epilithon ; photosynthesis ; respiration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Photosynthesis and respiration by the epilithic community on cobble in an arctic tundra stream, were estimated from oxygen production and consumption in short-term (4–12 h), light and dark, chamber incubations. Chlorophyll a was estimated at the end of each incubation by quantitatively removing the epilithon from the cobble. Fertilization of the river with phosphate alone moderately increased epilithic chlorophyll a, photosynthesis, and respiration. Fertilization with ammonium sulfate and phosphate, together, greatly increased each of these variables. Generally, under both control and fertilized conditions, epilithic chlorophyll a concentrations (mg m−2), photosynthesis, and respiration (mg O2 m−2, h−1) were higher in pools than in riffles. Under all conditions, the P/R ratio was consistent at ∼ 1.8 to 2.0. The vigor of epilithic algae in riffles, estimated from assimilation coefficients (mg O2 [mg Chl a]−1 h−1) was greater than the vigor of epilithic algae in pools. However, due to the greater accumulation of epilithic chlorophyll a in pools, total production (and respiration) in pools exceeded that in riffles. The epilithic community removed both ammonium and nitrate from water in chambers. Epilithic material, scoured by high discharge in response to storm events and suspended in the water column, removed ammonium and may have increased nitrate concentrations in bulk river water. However, these changes were small compared to the changes exerted by attached epilithon.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00013457
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Carbon isotope ratio and photosynthetic activity of phytoplankton in the eutrophic Mikawa Bay, Japan (1992)
    Springer
    Ecological research 7 (1992), S. 355-361 
    Details
    ISSN: 1440-1703
    Schlagwort(e): carbon isotope ratio ; photosynthesis ; phytoplankton
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Primary production by phytoplankton in the eutrophic Mikawa Bay, Japan, was studied by simultaneous measurements of natural carbon isotope ratio (δ 13C) and short-term carbon uptake rates (13C tracer study) of size-fractionated nannoplankton (〈10 μm) and net plankton (〉10 μm) samples. Short-term photosynthetic rates, which represent the physiological state of algae, were variable regardless of standing stock sizes. Theδ 13C values of particulate organic carbon (POC) in June and July displayed horizontal variations for both the net plankton fraction (−19.8 to −12.7‰) and the nannoplankton fraction (−22.0 to −12.8‰). For both fractions, low concentrations of POC had more negativeδ 13C values (−22 to −18‰). Highδ 13C values for the net plankton were found when POC concentrations were much higher, due to red tide. This suggests that the increase in algal standing crop for the net plankton fraction resulted from accelerated photosynthetic activity. However the nannoplankton fractions with higher POC values have relatively lowδ 13C values.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02347102
    Standort Signatur Erwartet Verfügbarkeit
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