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  • Life and Medical Sciences  (3)
  • X-ray diffraction  (3)
  • 42.60.By  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 58 (1994), S. 13-18 
    ISSN: 1432-0649
    Keywords: 42.60.By ; 32.30.Rj ; 32.70.-n ; 52.50.Jm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We propose a scheme for producing high gain recombination X-ray lasers on hydrogen-like Balmer α transitions by irradiating fibre targets with a 2 ps Chirped Pulse Amplification CPA beam of a Nd-glass laser facility. Very high gain coefficients for H-like C, N, O, F, Na Balmer α transitions are predicted. The optimum electron density and temperature for maximum gain operation scale approximately asN e ∼ 4 × 1013 Z 7 cm−3 and Te ∼ 7 × 10−3 Z 4 eV, respectively, at the time when maximum lasing gain appears. Significant improvement in gain performance of recombination X-ray lasers is predicted by using CPA ps pulse drivers.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0649
    Keywords: 42.60.By ; 42.60.Kg ; 42.10.Mg
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Coupling of a soft X-ray laser beam with a relaying concave mirror in a sequentially pumped amplifier geometry using the Ne-like Ge system has been studied experimentally. Preliminary observations indicate an increase in the spatial coherence of the amplified relayed beam. In addition, near-field imaging of one of the amplifier plasmas shows a double-lobed intensity pattern of the emergent beam indicating refractive guiding of the amplified beam with components both normal and tangential to the target surface.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Physics and chemistry of minerals 26 (1999), S. 206-211 
    ISSN: 1432-2021
    Keywords: Key words Iron ; Fe ; Si alloy ; X-ray diffraction ; Equation of state ; Thermoelasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract  We have carried out an in situ synchrotron X-ray diffraction study on iron and an iron-silicon alloy Fe0.91Si0.09 at simultaneously high pressure and temperature. Unit-cell volumes, measured up to 8.9 GPa and 773 K on the bcc phases of iron and Fe0.91Si0.09, are analyzed using the Birch-Murnaghan equation of state and thermal pressure approach of Anderson. Equation of state parameters on iron are found to be in agreement with results of previous studies. For both iron and Fe0.91Si0.09, thermal pressures show strong dependence on volume; the (∂KT/∂T)V values are considerably larger than those previously reported for other solids. The present results, in combination with our previous results on ɛ-FeSi, suggest a small dependency of the room-temperature bulk modulus upon the silicon content, less than 0.3 GPa for 1 wt.% silicon. We also find that substitution of silicon in iron would not appreciably change the thermoelastic properties of iron-rich Fe−Si alloys. If this behavior persists over large pressure and temperature ranges, the relative density contrast between iron and iron-rich Fe−Si alloys at conditions of the outer core of the Earth could be close to that measured at ambient conditions, i.e., 0.6% for 1 wt.% Si.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Physics and chemistry of minerals 26 (1999), S. 419-424 
    ISSN: 1432-2021
    Keywords: Key words Iron ; Fe-Si alloys ; X-ray diffraction ; Phase transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract In situ X-ray diffraction experiments at high pressure were carried out up to 8.9 GPa and 1100 °C to study phase transformations of iron and two iron-silicon alloys Fe0.91Si0.09 and Fe0.83Si0.17. For iron, the transformation from the bcc phase to the fcc phase was observed at pressures 3.8–8.2 GPa and temperatures that are consistent with previous in situ X-ray diffraction studies. Reversal of the transformation of iron was found to be sensitive to temperature; hysteresis of the transformation increased from 25 °C at 3.8 GPa to 100 °C at 7.0 GPa, primarily because the bcc-fcc phase boundary has a negative Clayperon slope. In the binary system Fe-Si, the observations of the present study indicate that the ferrite (bcc phase)-stabilizing behavior of silicon persists at high pressures and that the maximum solubility of silicon in the fcc phase increases with increasing pressure: (1) the transformation from the bcc phase to the fcc phase was observed in Fe0.91Si0.09 at 6.0, 7.4 and 8.9 GPa and the temperatures measured at the onset of the transformations were 300 °C higher than those in iron at similar pressures, (2) the transformation rate in Fe0.91Si0.09 was extremely sluggish compared to that of iron, and (3) the bcc-fcc phase transformation was not observed in Fe0.91Si0.09 at 4.7 GPa up to 1000 °C and in Fe0.83Si0.17 at 8.2 GPa and 1100 °C.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Physics and chemistry of minerals 27 (2000), S. 145-148 
    ISSN: 1432-2021
    Keywords: Key words MgO ; X-ray diffraction ; Thermal expansion ; Equation of state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Isobaric volume measurements for MgO were carried out at 2.6, 5.4, and 8.2 GPa in the temperature range 300–1073 K using a DIA-type, large-volume apparatus in conjunction with synchrotron X-ray powder diffraction. Linear fit of the thermal expansion data over the experimental pressure range yields the pressure derivative, (∂α/∂P) T , of −1.04(8) × 10−6 GPa−1 K−1 and the mean zero-pressure thermal expansion α0, T  = 4.09(6) × 10−5 K−1. The α0, T value is in good agreement with results of Suzuki (1975) and Utsumi et al. (1998) over the same temperature range, whereas (∂α/∂P) T is determined for the first time on MgO by direct measurements. The cross-derivative (∂α2/∂P∂T) cannot be resolved because of large uncertainties associated with the temperature derivative of α at all pressures. The temperature derivative of the bulk modulus, (∂K T/∂T) P , of −0.025(3) GPa K−1, obtained from the measured (∂α/∂P) T value, is in accord with previous findings.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 27 (1990), S. 152-158 
    ISSN: 1040-452X
    Keywords: Stallion spermatozoa ; Acrosome reaction ; Monoclonal antibody ; Zona-free hamster eggs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The acrosome of the stallion spermatozoon was visualized by indirect immunofluorescence with monoclonal antibody (18.6) which recognized an integral acrosomal membrane component. Localization was confirmed by electron microscopy using peroxidase labelled antibody. In fresh semen samples (n = 19), 73.9 ± 9.1% of the spermatozoa from five fertile stallions displayed a uniform bright fluorescence over their acrosome region. In two semen samples from an infertile stallion only 28% and 35% of spermatozoa showed the same pattern of fluorescence. Spermatozoa from fertile stallions incubated for up to 12 hours in TALP medium maintained motility and exhibited a significant progressive loss of acrosomes as detected by immunofluorescence. Alternatively, a similar loss of acrosomes could be induced with calcium ionophore A23187 over a 90 minute incubation. Ultrastructural observations and incubation with zona-free hamster eggs indicated that only with ionophore treatment was immunofluorescent acrosome loss correlated with a physiological acrosome reaction, while prolonged sperm incubation led to degenerative membrane changes. It was concluded that, if carefully validated, immunofluorescent localization of the acrosome of stallion sperm with monoclonal antibody could be used to monitor the acrosome reaction. Furthermore, definitive acrosome visualization would be valuable in assessing semen quality.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 26 (1990), S. 361-365 
    ISSN: 1040-452X
    Keywords: Stallion spermatozoa ; lonophore ; IVF ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: In vitro fertilizing ability of stallion spermatozoa was assessed using horse follicular oocytes matured in vitro. After collection, stallion spermatozoa were either: 1) washed and incubated in TALP medium with 3 mg/ml bovine serum albumin (BSA) and 10 μg/ml heparin for 4 h, 2) washed and incubated in TALP with 3 mg/ml BSA for 3 h and cultured for a further 1 h with 1 mM caffeine and 5 mM dbcAMP, 3) washed and incubated in TALP medium with 3 mg/ml BSA at pH 7.9-8.2 for 2-4 h, or 4) diluted and incubated in TALP medium with 10 mg/ml BSA and 7.14 μM calcium ionophore A 23187 for 5-10 min followed by washing. After a given pretreatment, suspensions were diluted into B2 medium to a concentration of 5 × 106 sperm/ml and co-incubated with oocytes for 12 h or 24-48 h. In the ionophoretreated group, 18 of 54 oocytes (33%) were fertilized by 12 h, and 11 of 45 (24%) cleaved by 24-48 h. Evidence of fertilization was not found in the oocytes incubated with spermatozoa from other treatment procedures.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 8 (1988), S. 297-306 
    ISSN: 0741-0581
    Keywords: Defects ; Polymorphs ; Structure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We review recent results obtained at Northwestern using high-resolution electron microscopy to study high-temperature superconductors. While in general these materials form large, very perfect single crystal grains which display very few imperfections, there is also evidence of slip defects, amorphous regions, and order-disorder transformations. We also report that the gadolinium-based superconductors and in one case yttrium-based superconductors show evidence for some copper solid solubility in the form of copperrich planar defects. The structure of a metastable trigonal polytype is also reported, as are the effects of electron beam and water vapor damage to the materials.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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