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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Czechoslovak journal of physics 47 (1997), S. 533-536 
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effects of the aluminum substitution and degree of crystallinity upon the lattice-dynamical and electrical properties of synthetic goethites are determined from their Mössbauer spectra. The temperature variations of the centre shift could be calculated using the Debye approximation for the lattice vibrations. The parameters incorporated in this model exhibit a maximum at a certain aluminum content within each of the four series in this study. It has been found that the principal axis of the EFG remains perpendicular to the direction of the magnetic hyperfine field when the aluminum content and/or the crystallinity change.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2048
    Keywords: Key words: Aerenchyma ; Cell death ; Oryza ; Plasmodesma ; Root
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Cellular events which occur prior to cell collapse were examined in the root cortex of rice (Oryza sativa L.) during aerenchyma formation. Cell collapse started at a specific position in the mid cortex. These cells were distinct in shape from those located towards the periphery. Furthermore, cell collapse was preceded by acidification and the loss of plasma-membrane integrity in cells of the mid cortex. Subsequent death of neighboring cells followed a radial path. Microinjection of molecules of different sizes conjugated with fluorescein isothiocyanate (FITC) showed a molecular exclusion limit of between 9.3 and 19.6 kDa in the root cortex. Furthermore, large molecules, i.e. those around 9.3 kDa, were predominantly transferred in a radial direction, which coincided with the path of sequential cell death.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2048
    Keywords: Key words: Aerenchyma ; Cell death ; Oryza ; Root ; Stress (NaCl)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. The mode of action of NaCl in terms of cell proliferation and cell death was examined in seminal roots of rice plants (Oryza sativa L.). Salt/sodium chloride was inhibitory to cell number increase and to cell death in cortical tissue, whereas final cortical cell size was the same as in control roots that were not exposed to NaCl. It seems that NaCl may stimulate the transition phase from cell division to cell elongation. Further analysis of the role of NaCl in the suppression of cortical cell death was confined to a delay in the early stage of cell collapse, which was caused by tonoplast disruption, and plasma-membrane destruction. Sodium chloride did not have any effect on the cell-to-cell movement of macromolecules in the root cortex. In-situ hybridization studies indicated that expression of the gene for tonoplast intrinsic protein (rTip1) was localized predominantly in the epidermal and exodermal cells as well as in metaxylem cells in seminal roots. Upon NaCl treatment, the intensity of rTip1 gene expression was raised in the cortical parenchyma, suggesting that salt plays a role in the rapid onset of cell elongation.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International journal of parallel programming 12 (1983), S. 1-11 
    ISSN: 1573-7640
    Keywords: Trees ; regular expressions ; expansive tree grammars ; regularity-preserving transformations ; context-free languages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Regular-like expressions provide a compact notation for the explicit description of context-free languages. In this paper we extend these concepts by establishing a one-to-one correspondence between expansive tree languages and regular-like sets of trees. Algorithms are developed for constructing an expansive tree grammar whose language is defined by a given regular-like tree (RLT) expression, and vice versa. These results are then used to obtain RLT equations that describe sets of tree resulting from regularity-preserving transformations associated with three types of errors commonly found in practice.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1572-9540
    Keywords: Al-substituted iron oxides ; Mössbauer spectroscopy ; external fields
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this contribution, the effect of high external magnetic fields upon the Mössbauer spectra of aluminous α- and γ-Fe2O3, of aluminous α- and γ-FeOOH and of aluminous Fe3O4 is reviewed. It is shown that the shapes of these spectra are characteristic of these materials and also to some extent of their crystallinities and Al-for-Fe substitutions. Based upon this evaluation, the potential for application of external-field Mössbauer spectroscopy to soil-related analytical purposes is demonstrated for two soil samples. Limitations of the technique are discussed. Finally, some suggestions for further research in this field are indicated.
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  • 6
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Mössbauer spectroscopy is a powerful direct technique for the identification and quantification of iron oxides and (oxy)hydroxides in soils and sediments. However, further characterization with respect to structural properties such as crystallinity, Al substitution, stoichiometry, water content, etc. is rather limited. With some examples of synthetic and natural goethite and hematite sample series it is illustrated that the hyperfine parameters depend on much more structural features than the Al content and crystallinity alone. Neither the Morin transition in hematite nor the Verwey transition in magnetite is directly applicable for analytical purposes in natural samples.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Hyperfine interactions 122 (1999), S. 39-46 
    ISSN: 1572-9540
    Keywords: Al-goethites ; crystallinity ; magnetic properties ; Mössbauer spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper reviews a profound Mössbauer study on the magnetic properties of goethites with varying crystallinity and Al-content. It has been found that both the cluster-ordering and the superferromagnetic models reproduce the temperature dependencies of the average hyperfine fields quite well. However, the magnetic transition temperatures predicted by the cluster-ordering model are in better agreement with those measured from thermoscan experiments. On the other hand, it has been found that the hyperfine field of maximum probability at low temperatures follows the spin–wave law for antiferromagnets. Linear relationships between the saturation hyperfine fields, the inter-sublattice exchange interactions, and the Néel temperatures to the Al-content and crystallinity could be derived. On the other hand, applied-field Mössbauer spectroscopy seems to suggest that the anisotropy field can differentiate between poor crystallinity and Al-content, and that a certain degree of ferrimagnetism occurs at higher Al-contents.
    Type of Medium: Electronic Resource
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  • 8
    Publication Date: 2003-08-01
    Print ISSN: 1070-6631
    Electronic ISSN: 1089-7666
    Topics: Physics
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  • 9
    Publication Date: 2013-05-07
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
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  • 10
    Publication Date: 2013-02-07
    Description: Background: T-cell intracellular antigen (TIA) proteins function as regulators of cell homeostasis. These proteins control gene expression globally at multiple levels in response to dynamic regulatory changes and environmental stresses. Herein we identified a micro(mi)RNA signature associated to transiently TIA-depleted HeLa cells and analyzed the potential role of miRNAs combining genome-wide analysis data on mRNA and miRNA profiles. Results: Using high-throughput miRNA expression profiling, transient depletion of TIA-proteins in HeLa cells was observed to promote significant and reproducible changes affecting to a pool of up-regulated miRNAs involving miR-30b-3p, miR125a-3p, miR-193a-5p, miR-197-3p, miR-203a, miR-210, miR-371-5p, miR-373-5p, miR-483-5p, miR-492, miR-498, miR-503-5p, miR-572, miR-586, miR-612, miR-615-3p, miR-623, miR-625-5p, miR-629-5p, miR-638, miR-658, miR-663a, miR-671-5p, miR-769-3p and miR-744-5p. Some up-regulated and unchanged miRNAs were validated and previous results confirmed by reverse transcription and real time PCR. By target prediction of the miRNAs and combined analysis of the genome-wide expression profiles identified in TIA-depleted HeLa cells, we detected connections between up-regulated miRNAs and potential target genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) database analysis suggest that target genes are related with biological processes associated to the regulation of DNA-dependent transcription, signal transduction and multicellular organismal development as well as with the enrichment of pathways involved in cancer, focal adhesion, regulation of actin cytoskeleton, endocytosis and MAPK and Wnt signaling pathways, respectively. When the collection of experimentally defined differentially expressed genes in TIA-depleted HeLa cells was intersected with potential target genes only 7 out of 68 (10%) up- and 71 out of 328 (22%) down-regulated genes were shared. GO and KEGG database analyses showed that the enrichment categories of biological processes and cellular pathways were related with innate immune response, signal transduction, response to interleukin-1, glomerular basement membrane development as well as neuroactive ligand-receptor interaction, endocytosis, lysosomes and apoptosis, respectively. Conclusion: All this considered, these observations suggest that individual miRNAs could act as potential mediators of the epigenetic switch linking transcriptomic dynamics and cell phenotypes mediated by TIA proteins.
    Electronic ISSN: 1471-2199
    Topics: Biology
    Published by BioMed Central
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