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  • 1
    Electronic Resource
    Electronic Resource
    Effects of ion bombardment on the chemical reactivity of gallium arsenide(100): variation of bombarding ion mass (1990)
    s.l. : American Chemical Society
    Chemistry of materials 2 (1990), S. 173-180 
    Details
    ISSN: 1520-5002
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/cm00008a019
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  • 2
    Electronic Resource
    Electronic Resource
    A study of intermetallic compound formation in a copper–tin bimetallic couple (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 3681-3688 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The formation of intermetallics in copper–tin bimetallic couples has been studied from room temperature to 183 °C by measuring the evolution of contact resistance and composite electrical resistance with time and temperature in order to assess the kinetic behavior of the system. X-ray diffractogram (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) studies have also been performed on the samples. As regards bulk diffusion, copper diffuses interstitially into tin rapidly at room temperature with the formation of η'-Cu6Sn5 intermetallic compound. Further diffusion through this phase as evaluated by composite electrical resistivity measurements is given by 0.40 eV, assuming a model of defect-assisted diffusion into the grains. The grain-boundary diffusion is found to occur with an activation energy of 0.78 eV as estimated from contact resistivity measurements. SEM confirms the presence of grain-boundary diffusion of tin in copper, whereas XRD and TEM measurements indicate the growth of η' intermetallics at room temperature which exists up to 90 °C when it transforms to the ε-Cu3Sn phase. The presence of tin whiskers on the tin surface has also been occasionally observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.345324
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  • 3
    Electronic Resource
    Electronic Resource
    Observation of charge storage and intersubband relaxation in resonant tunneling via a high sensitivity capacitive technique (1990)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2820-2822 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In suitably designed resonant tunneling double barriers the capacitance-voltage curve exhibits well-defined features corresponding to the charging and discharging of the quantum well. From the bias dependence of the electron density in the well we find that in our thick parabolic wells, electrons tunneling into the excited states relax to the lowest subband and sequentially tunnel out. Our experiments allow us to obtain the charge density accumulated in the well and the tunneling escape rate of electrons out of the well.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.103752
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  • 4
    Electronic Resource
    Electronic Resource
    Compositional characteristics and phase equilibria in manganiferous iron formations from a high-grade terrain near Satnuru, Karnataka, India (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of metamorphic geology 8 (1990), S. 0 
    Details
    ISSN: 1525-1314
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Manganese-rich and manganese-poor iron formations which occur as thin layers in the Halaguru-Satnuru area, south of Kabbaldurga, Karnataka, India are chemically intermediate between the ‘Algoma’and ‘Lake Superior’types, but higher in their MnO and TiO2 contents. The rocks are of four petrographic varieties: (a) quartz-magnetite-orthopyroxene-clinopyroxene, (b) quartz-magnetite-orthopyroxene-clinopyroxene-garnet, (c) quartz-magnetite-clinopyroxene-garnet, and (d) quartz-magnetite-clinopyroxene-garnet-plagioclase.In the orthopyroxene-clinopyroxene pairs, Mn-Mg and Mn-Fe exchange is ideal irrespective of the MnSiO3 contents of orthopyroxenes (0.6–1.8 mol. % in Mn-poor and 15–25 mol. % in Mn-rich compositions). Mg-Fe exchange in the same pair is however non-ideal. Mn-Fe exchange in orthopyroxene-garnet pairs is ideal. The distribution patterns in the other binaries are inconclusive regarding ideality of exchange. Orthopyroxene-garnet and clinopyroxene-garnet geothermometers, modified for high spessartine contents, give temperatures of 800 ± 30° C. A modified version of the Harley (1984) geothermometer registers 740 ± 60° C, in agreement with the consensus temperature value.The equilibrium log ffo2 values in the iron formations, as calculated from the reaction 6FeSiO3+ O2= 2Fe3O4+ 6SiO2 are in the range of −14.2 to −15.5. Algebraic analysis of variations of fo2 with composition of phases indicates buffering of O2 in the rocks. The absence of grunerite in these assemblages is compatible with XH2O being less than 0.3 in the ambient fluid. Computations from volatile equilibria in the C-O-H system, however, predict high XH2O values (〉0.7) at ac= 1.0, implying that the activity of graphite must have been greatly reduced—this is in accordance with the absence of graphite in these rocks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1525-1314.1990.tb00484.x
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  • 5
    Electronic Resource
    Electronic Resource
    Plant regeneration from mesophyll protoplasts of Diplotaxis muralis, a wild crucifer (1990)
    Springer
    Plant cell reports 8 (1990), S. 722-725 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mesophyll protoplasts from leaves of aseptically grown shoot tips of Diplotaxis muralis were isolated (6.2–7.1×105 protoplasts/g fresh weight of tissue) using one step enzyme digestion. The protoplasts (71% viability) underwent divisions (4.2+0.1%) on plating in M8PS2 medium and ultimately formed calli with 0.45+0.03% plating efficiency. Plant regeneration could be achieved both through embryogenesis and organogenesis. The efficiency of plant regeneration through organogenesis was 9 times higher than embryogenesis. Forty eight out of 52 plants regenerated so far from 3 independent experiments were normal with respect to fertility and meiotic chromosomal behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00272103
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  • 6
    Electronic Resource
    Electronic Resource
    “Erussica”, the intergeneric fertile somatic hybrid developed through protoplast fusion between Eruca sativa Lam. and Brassica juncea (L.) Czern. (1990)
    Springer
    Theoretical and applied genetics 79 (1990), S. 561-567 
    Details
    ISSN: 1432-2242
    Keywords: Intergeneric somatic hybridization ; Brassica + Eruca ; Somatic hybrid ; Partial somatic hybrid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Hypocotyl calli-derived protoplasts of two cultivars of Brassica juncea (2n=36), a major oil-seed crop, were fused with normal as well as γ-irradiated mesophyll protoplasts of Eruca sativa (2n=22). The irradiation of the Eruca fusion partner increased the plating efficiency as well as the morphogenic potentiality of the fusion products over the normal fusion. Fertile plants could be regenerated from such fusion products. Analysis of 63 out of 181 plants regenerated showed that, indeed, 11 somatic hybrids (2n=58) and 10 partial somatic hybrids (chromosome number ranged between 50 and 56) had been obtained. Pollen viability (0%–82.9%) and seed set (0%–50%) of the hybrids indicated them to be useful for future studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226168
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  • 7
    Electronic Resource
    Electronic Resource
    Induction of mitosis in polytene nuclei and hormonal effect on nuclear changes during callus initiation in diploid Urginea indica Kunth. (liliaceae) (1990)
    Springer
    Genetica 80 (1990), S. 9-15 
    Details
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bulb scale and inflorescence explants of Urginea indica Kunth. (2n=20) were cultured in vitro on modified Murashige & Skoog's medium with different hormonal composition. Media containing 2,4-dichlorophenoxy-acetic acid (2,4-D) (2 and 4 mgl−1) and α-naphthalene-acetic acid (NAA) (2 mgl−1) could induce callus in inflorescence explants. Combination of 2,4-D (4 mgl−1) + NAA (2 mgl−1) + Kinetin (2 mgl−1) only could induce callus formation in scale explants. The bulb scale explants contained mostly diploid cells while the inflorescence explants contained cells with nuclear DNA content ranging from 2C to 64C. The lowest karyological heterogeneity was recorded in callus derived from bulb scale and in callus derived from inflorescence induced with NAA. The highest variability was recorded on media with 2,4-D alone. Induction of division, probably of the pre-existing polytenic nuclei in the inflorescence explant, has been suggested to be the cause of origin of polyploid cells in such cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00120115
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  • 8
    Electronic Resource
    Electronic Resource
    Error-free matrix symmetrizers and equivalent symmetric matrices (1990)
    Springer
    Acta applicandae mathematicae 21 (1990), S. 291-313 
    Details
    ISSN: 1572-9036
    Keywords: 65F ; 65G ; Complex symmetric matrix ; equivalent symmetric matrices ; error-free matrix symmetrizers ; floating-point modular arithmetic ; Hessenberg matrices ; nonsymmetric eigenvalue problem ; parallel implementation ; QR transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A symmetrizer of the matrix A is a symmetric solution X that satisfies the matrix equation XA=A′X. An exact matrix symmetrizer is computed by obtaining a general algorithm and superimposing a modified multiple modulus residue arithmetic on this algorithm. A procedure based on computing a symmetrizer to obtain a symmetric matrix, called here an equivalent symmetric matrix, whose eigenvalues are the same as those of a given real nonsymmetric matrix is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00047212
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  • 9
    Electronic Resource
    Electronic Resource
    Infrared spectra of alkali treated jute stick (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 329-336 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The infrared spectra of alkaline jute stick have been discussed and compared to that of untreated and control sample. A higher shift in the O—H and lower shift in the C—H stretching frequencies were observed in alkaline sample. The presence of a strong band at 1440-1430 cm-1 may be due to the coupling of COO- frequency with CH2 deformation frequency. The C—O stretching mode at 1240 cm-1 disappears on alkaline treatment with the formation of new peaks at 1265 and 1225 cm-1. The β-glucosidic band at 895 cm-1 is shifted to 880 cm-1 with doubled intensity in alkaline jute stick.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410125
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  • 10
    Electronic Resource
    Electronic Resource
    Accumulation of heavy metals by oscillatoria sp. (1990)
    Berlin : Wiley-Blackwell
    Acta Biotechnologica 10 (1990), S. 469-471 
    Details
    ISSN: 0138-4988
    Keywords: Life Sciences ; Life Sciences (general)
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Microorganisms are the dominatign inhabitants of the soil, and there is an icnreasing tendency to apply heavy metals in agricultural practice. The ecological balance may be distrubed unknowingly if we do nogt measure the tolerance by the microorganisms of these heavy metals. It has been found in a Oscillatoria model system that widely used heavy metals have a high degree of toxicity to this cyanobacter.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/abio.370100517
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