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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 4358-4360 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In order to study the local atomic environments of both B and Fe in Fe3B1−xCx (0.1≤x≤0.4), NMR measurements of the hyperfine field distributions for 10B, 11B, and 57Fe have been performed at 4.2 K and from 10 to 60 MHz. It was found that the 11B and 57Fe NMR frequencies do not change with C concentration. From these results, the 11B NMR frequency characteristic of orthorhombic Fe3B was unambiguously determined to be 36.3 MHz, which is in good agreement with the value obtained for the orthorhombic Fe3B phase prepared by annealing amorphous Fe80B20. Our results show that the substitution of C atoms for B atoms has a small effect on the hyperfine field at both the B and Fe nuclei as well as on the magnetic moment of the Fe atoms.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 4349-4351 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The rapidly quenched, crystalline, Fe-rich Fe100−xMx system has been studied by 57Fe Mössbauer effect spectrometry. Boron and carbon alloys were found to have regions with cementite local structure. Small amounts of fcc γ-Fe were also observed in some of the cases. Furthermore, almost half of the carbon was concluded to be in interstitial solution. Upon annealing the carbon alloy, the fcc phase disappears to benefit formation of the cementite. In contrast, the alloys with aluminum, silicon, and phosphorous are substitutional solid solutions. After being annealed at 1073 K, they do not show changes in their hyperfine interactions nor in their crystalline structure. However, the lattice parameter of the alloy with phosphorous unexpectedly increased from a value below that corresponding to pure iron to another above it. These results are discussed on the basis of the metalloid solubilities in iron and their atomic sizes.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3231-3233 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Based on a knowledge of the NMR spectra for FeB, Fe2B, orthorhombic Fe3B (o-Fe3B), and body-centered-tetragonal Fe3B (bct-Fe3B), the phases produced during the annealing of Fe-B amorphous alloys can be identified with greater sensitivity by NMR techniques than by x-ray diffraction. In the present work, a combination of x-ray diffraction experiments and spin-echo NMR measurements of the hyperfine field distributions for the 10B, 11B, and 57 Fe nuclei has been performed on both as-quenched and annealed Fe100−xBx (14≤x≤25) amorphous alloys. In general terms, it was found that annealing at temperatures near 400 °C resulted in crystallization products which included bct-Fe3B, while annealing at approximately 800 °C leads to the formation of o-Fe3B. The behavior of the B hyperfine field indicates that, for the Fe100−xBx amorphous alloys, an o-Fe3B-like local order is favored in the low B concentration regime, and a bct-Fe3B-like local order is favored in the high B concentration regime.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 1671-1675 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The crystallization of Fe100−xBx amorphous alloys (x=14, 20, and 25), prepared by rapid quenching from the melt, was studied by Mössbauer effect spectroscopy. In general, the present results support recent nuclear magnetic resonance studies (performed on the same samples used in this work), which indicated that the amorphous material had a body-centered-tetragonal Fe3B-like short-range order for x=25 but an orthorhombic Fe3B-like one for x=14. For x=25, annealing at about 400 °C led to the formation of almost pure body-centered-tetragonal Fe3B. On the other hand, thermal treatments at about 800 °C produced a mixture of phases for all the compositions. For x=14, formation of body-centered-tetragonal Fe3B was not observed in any case. In addition, the present Mössbauer results, combined with the previous nuclear magnetic resonance ones, show that boron and iron atomic surroundings evolve differently when alloys with x=14 are annealed at 390–420 °C. In the boride phase, the 57Fe Mössbauer signal remained "amorphouslike'' in contrast with the 11B nuclear magnetic resonance signals which became sharp and corresponded to those in tetragonal and orthorhombic Fe3B and in Fe2B. These results would indicate that under these experimental conditions the surroundings of the boron atoms become ordered before the surroundings of the iron atoms.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 66 (1989), S. 875-880 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The transformation of the Fe0.91B0.09 rapidly quenched crystalline alloy from its original metastable state to its equilibrium state has been studied by Mössbauer effect spectroscopy. It was found that the alloy transforms in a single step from a fine dispersion of orthorhombic-Fe3B-like complexes embedded in metallic bcc iron to a system consisting of Fe2B precipitates in the α-Fe matrix. The kinetics and temperature dependence of the process have been measured. It was determined that the relative fraction of Fe2B increases as Ω=1−exp(−kt3/2) with k=k0 exp(−Ea/kBT), indicating a diffusion-controlled, Arrhenius-type transformation, where k0=(1.92±0.26)×1014 s3/2 and Ea=(3.56±0.07) eV/atoms. Magnetization versus temperature scans have been simulated and compared to previously measured scans. A simple picture of the transformation process is given.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 26-31 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Signal-beam amplification is achieved in degenerate two-wave mixing experiments in liquid crystals at the wavelength λ=10.6 μm of the cw CO2 laser. The origin of the dynamic grating is the large thermal index change that arises when the cell operates near the phase transition temperature. Maxwell's equations are analytically solved for the calculation of the amplitude variations of the incident waves (Ip@B:pump, Is@B:signal) and of the self-diffracted wave (I−1). It is shown that energy transfer arises from the contribution of the π/2 component of the index modulation generated by the interference of (Ip,I−1). The resulting three-wave model yields good agreement with the experimental results.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 58 (1986), S. 73-76 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 60 (1988), S. 323-328 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 52 (1987), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Heat inactivation of polyphenoloxidase (PPO) in sultana grapes between 83° and 98°C followed zero order kinetics with an activation energy of 13.7–16.7 kcal/mol. A high correlation (r = 0.973) was found between the residual PPO activity and darkness of the raisins (Hun-terlab L value) after drying at 50°C. Reaction rate for enzymatic browning increased with higher water activities while non-enzymatic browning showed the typical bell-shaped curve with a maximum around 0.8. Light-colored raisins were obtained without the use of SO2 by pretreating the grapes with a 2 min dip in 93°C water that inactivated PPO and improved mass transfer through the skin. This latter effect was compared to that of other treatments such as ethyl oleate and caustic soda by drying studies and scanning electron microscopy.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Histopathology 15 (1989), S. 0 
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Eleven benign and five malignant choroid plexus papillomas in children and adults were studied immunohistologically with a panel of antibodies against glial fibrillary acidic protein, S-100 protein, vimentin, desmin, epithelial membrane antigen and two different cytokeratins (LP34 and CAM 5.2). Glial fibrillary acidic protein was focally present in epithelial tumour cells, in cells within solid areas and in clusters of cells within the stroma. S-100 protein was diffusely present in tumour cells with focal accentuation. Vimentin was present in all cases, the epithelial tumour cells demonstrating strong and diffuse positivity with perinuclear accentuation; malignant tumours, however, showed stronger positivity than benign ones. Desmin was negative in all tumours. Epithelial membrane antigen and cytokeratin (LP34) were demonstrated in four of five malignant tumours but were absent in the benign ones; CAM 5.2 reacted with four of five malignant tumours and also reacted with eight of the 11 benign ones. The significance of these findings is discussed in respect of the ontogeny of these tumours.
    Type of Medium: Electronic Resource
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