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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of carbon nitride thin films prepared by dual ion beam sputtering (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 764-766 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Carbon nitride thin films obtained by dual ion beam sputtering have been investigated by electron energy-loss spectroscopy (EELS), transmission electron microscopy, and Fourier transform infrared spectroscopy. The nitrogen content in the films depends on deposition conditions. A maximum value of N/C=0.8 has been achieved. A new peak at 286.7 eV energy loss in the C K-edge EELS spectra has been assigned to C=N bonds with C in the sp2 hybridization state. In addition, experimental evidences are presented of the formation of β-C3N4 crystallites embedded in a layer of a polymer like CNx amorphous phase. An evaluation of the experimental parameters that lead to the highest N content in the films is also included. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117884
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  • 2
    Electronic Resource
    Electronic Resource
    Somatic embryogenesis and plant regeneration from barley cultivars grown in Spain (1998)
    Springer
    Plant cell reports 17 (1998), S. 902-906 
    Details
    ISSN: 1432-203X
    Keywords: Key words Barley ; Somatic embryogenesis ; Plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thirty-two barley cultivars grown in Spain, 18 of the two-row type and 14 of the six-row type, were screened for plant regeneration from cultured immature embryos. Although there was much variation in regeneration capacity among the cultivars, plants were obtained from all cultivars except Almunia. No statistical differences were found in the percentage of regeneration between two- and six-row types. The influence of the auxins 2,4-dichlorophenoxyacetic acid, dicamba, and picloram on the induction and maintenance of embryogenesis and regeneration capacity after 3–4 months in culture, were evaluated for cultivars Cobra, Hop and Reinette. Hop had the highest rates of maintenance of embryogenic capacity and plant regeneration. The medium containing dicamba gave the best embryogenic callus induction, maintenance and regeneration. Five regeneration media, differing in growth regulators and micronutrient composition, as well as partial desiccation of the calli before regeneration, were tested. The regeneration medium containing 10 μm copper sulfate gave the best results. Regeneration frequencies after 3–4 months in culture of cultivar Hop were raised from 59.5 to 93.7% in this medium. Silver nitrate and partial desiccation of the calli also enhanced plant regeneration, but the medium containing 10 μm of silver nitrate reduced root formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050506
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  • 3
    Electronic Resource
    Electronic Resource
    Desiccated doubled-haploid embryos obtained from microspore culture of barley cv. Igri (1999)
    Springer
    Plant cell reports 18 (1999), S. 924-928 
    Details
    ISSN: 1432-203X
    Keywords: Key words Barley ; Desiccation ; Embryos ; Doubled haploids ; Microspores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Barley microspore-derived doubled-haploid embryos have been produced in vitro. The development of embryo desiccation technology will allow long-term storage, germplasm preservation and low delivery cost. Treatment of the microspore-derived embryos was essential to induce desiccation tolerance and to arrest further development and plant regeneration. At the concentrations used, a treatment with trehalose was more efficient than with sucrose, and mannitol was harmful to the embryos. Up to 80% of the desiccated embryos produced complete green plants when transferred to regeneration medium, by the application of a 0.6 m trehalose or a 10–5 m abscisic acid treatment to the embryos in the culture induction medium. The morphology of these plants was similar to plants produced directly from non-desiccated embryos.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050685
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  • 4
    Electronic Resource
    Electronic Resource
    Neurotransmitter characteristics of neurons projecting to the supramammillary nucleus of the rat (1999)
    Springer
    Anatomy and embryology 200 (1999), S. 377-392 
    Details
    ISSN: 1432-0568
    Keywords: Key words Mesencephalic tegmental nuclei ; Basal forebrain ; Choline acetyltransferase ; GABA ; Excitatory amino acid ; Neuropeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Retrograde labelling was combined with immunohistochemistry to localize neurons containing choline acetyltransferase, gamma-aminobutyric acid (GABA), glutamate, serotonin, somatostatin, Leu-enkephalin, neurotensin, and substance P-immunoreactivity in neurons projecting to the supramammillary nucleus in the rat. Injections of wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP) into the supramammillary nucleus resulted in retrogradely labelled neurons in the medial septal nucleus, the nuclei of the diagonal band of Broca, the infralimbic cortex, the medial and lateral preoptic nucleus, the subiculum, the laterodorsal tegmental nucleus, the compact subnucleus of the central superior nucleus and the dorsal raphe nucleus. In the medial septal nucleus and in the nuclei of the diagonal band of Broca, 80–85% of WGA-HRP- labelled neurons (30–40 per section) were also immunoreactive for choline acetyltransferase and small numbers of WGA-HRP-labelled neurons were immunoreactive for GABA, glutamate, neurotensin or substance P. In the medial preoptic nucleus, 85–90% of retrogradely labelled neurons (25–30 per section) were immunoreactive for somatostatin and a few WGA-HRP-labelled neurons displayed neurotensin-immunoreactivity. In the rostroventral part of the subiculum, small numbers of retrogradely labelled neurons were also immunoreactive for neurotensin or for glutamate. In the laterodorsal tegmental nucleus, 90% of WGA-HRP-labelled neurons (20–25 per section) were immunoreactive for choline acetyltransferase and small numbers of retrogradely labelled neurons also displayed substance P immunoreactivity. In the compact subnucleus of the central superior nucleus, 50–60% of retrogradely labelled neurons (15–20 per section) were also immunolabelled for GABA and approximately 30–40% of WGA-HRP-labelled neurons (10–12 per section) were immunoreactive for Leu-enkephalin. The compact subnucleus of the central superior nucleus also contained small numbers of retrogradely labelled neurons that displayed neurotensin immunoreactivity. In the dorsal raphe nucleus, 80–85% of WGA-HRP- labelled neurons (30–40 per section) were also immunoreactive for serotonin and small numbers of retrogradely labelled neurons displayed neurotensin or glutamate immunoreactivity. These results suggest that the multiple neurochemicals contained in ascending and descending projections to the SuM participate in complex interactions in the transmission process of SuM neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050287
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  • 5
    Electronic Resource
    Electronic Resource
    Immunoelectron microscopic study of γ-aminobutyric acid inputs to identified thalamocortical projection neurons in the anterior thalamus of the rat (1999)
    Springer
    Experimental brain research 126 (1999), S. 369-382 
    Details
    ISSN: 1432-1106
    Keywords: Key words Anterodorsal thalamic nucleus ; Anteroventral thalamic nucleus ; Retrograde labelling ; Postembedding immunoelectron microscopy ; Inhibitory synapses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  We have carried out a semi-quantitative ultrastructural study to determine the characteristics and distribution of γ-aminobutyric acid (GABA)-containing constituents of the anterodorsal (AD) and anteroventral (AV) thalamic nuclei in adult rats. We used a polyclonal antibody to GABA and a postembedding immunogold detection method in animals in which the cortical projection neurons of these nuclei had been labelled by retrograde transport of cholera toxin/horseradish peroxidase (HRP) injected into the retrosplenial granular cortex. Two types of GABA-immunopositive structures were identified, with gold particle densities 4–40 times higher than the highest densities over blood-vessel lumens and areas of empty resin: (1) an apparently homogeneous population of axon terminals with Gray type-2 (symmetric) synaptic contacts corresponding to F-axon terminals; and (2) small–medium sized myelinated axons scattered individually or in small groups within the neuropil which may be their parent axons. These axons and terminals may originate from the ipsilateral thalamic reticular nucleus; others may arise from the basal forebrain or brainstem. The GABA-immunopositive terminals comprised approximately 16% of all axon terminal profiles in AD and 12% in AV, a significant difference. However, because the immunoreactive axon terminals in AD were significantly larger than those in AV (1.09±0.47 µm2 vs 0.90±0.43 µm2) and would therefore be encountered more frequently, it is not possible to conclude that the GABAergic innervation of AD is heavier than that of AV. The GABA-positive terminals established synaptic contacts with cell bodies and dendrites of all sizes (some of which were HRP-labelled) with the following frequency distribution (AD/AV, no significant difference): somata 5%/7%; large dendrites (≥1.5 µm) 14%/9%; medium dendrites (1.00–1.49 µm) 35%/45% and small dendrites (〈1 µm) 46%/40%. Despite evidence from previous studies, we found no evidence in this study for the presence of GABAergic interneurons or for GABA-containing projection neurons in AD or AV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050744
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  • 6
    Electronic Resource
    Electronic Resource
    Calibration of the Probing Depth by Total Electron Yield of EXAFS Spectra in Oxide Overlayers (Ta2O5, TiO2, ZrO2) (1997)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 25 (1997), S. 707-714 
    Details
    ISSN: 0142-2421
    Keywords: x-ray absorption spectroscopy ; total electron yield ; oxides ; EXAFS probing depth ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Calibration of the probing depth by x-ray absorption spectroscopy (XAS) in oxide materials is intended by measurement of the total electron yield (TEY) of electrons ejected by absorption of the radiation. Measurements have been carried out for three series of electrolytic metal oxide overlayers with different thickness. The experiments have been conducted at the Ti K, Ta LIII and Zr K edges. Analysis of the XAS spectra is carried out by factor analysis and conventional Fourier transformation and fitting analysis. The data showed that the information depth by XAS follows the order ZrO2〉TiO2〉Ta2O5 at the Ti K, Ta LIII and Zr K edges.As an alternative, the absorption spectra of the same samples were measured in the conversion electron yield (CEY) mode: i.e. by measuring the current of He+ ions produced by the ejected electrons in an atmosphere of He in contact with the sample. Here, the information depth is slightly different from that obtained by TEY. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chemical Analysis of Ternary Ti Oxides using Soft X-ray Absorption Spectroscopy (1997)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 25 (1997), S. 804-808 
    Details
    ISSN: 0142-2421
    Keywords: Ti oxides ; x-ray absorption spectroscopy ; electronic structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: We measured the O 1s and Ti 2p X-Ray Absorption Spectroscopy (XAS) spectra of a series of ternary Ti oxides. The spectra of A12TiO5 are compared to those of TiO2 and the physical mixture TiO2-Al2O3. The spectra reflect important differences in the electronic structure caused by changes in the chemical bonding. It is also shown that XAS can be used to distinguish a true compound like Al2TiO5 from a stoichiometric mixture like TiO2-Al2O3. The differences in the spectra of NiTiO3, SrTiO3, BaTiO3 and PbTiO3 are discussed in terms of the different chemical environment and the local coordination. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Quantitative chemical depth profiles of ZrN/BN multilayers Dedicated to Professor Siegfried Hofmann on the occasion of his 60th birthday. (1998)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 26 (1998), S. 806-814 
    Details
    ISSN: 0142-2421
    Keywords: multilayers ; ZrN ; BN ; AES ; RBS ; depth profiling ; factor analysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Multilayers of ZrN/BN have been deposited on Si(100) using a double ion beam sputtering system. The multilayers have been characterized by transmission electron microscopy, Rutherford backscattering spectroscopy and Auger electron spectroscopy (AES) depth profiles in order to get a quantitative analysis of the components and contaminants in the different layers and at their respective interfaces. Factor analysis is used to deconvolute the different chemical states of the components and to identify secondary phases and compounds that determine the quality of the multilayer. Two secondary phases have been observed at the different interfaces: one is associated with the incorporation of oxygen, mainly in the zirconium layer, and leads to the formation of ZrNxOy. In addition we have observed that Ar bombardment during the AES depth profile leads to the formation of ZrBxNy in all the interfaces. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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