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  • 1
    Electronic Resource
    Electronic Resource
    Concentration dependence of UV and electron-excited Tb3+ luminescence in Y3Al5O12 (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 5450-5456 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The emission spectrum of Tb3+ substituted in YAG to various concentrations (x in Y3−xTbxAl5O12 ranges from 3×10−5 to 3×10−1) has been measured on samples prepared by two different methods. These methods are powder preparation by coprecipitation and growth of crystalline layers by liquid-phase epitaxy. The spectrum consists of two groups of lines, one group around 550 nm originating from the 5D4 level and one group around 450 nm from the 5D3 level. The intensity of the two groups of lines depends on the method of excitation. In the case of UV excitation (λ=254 nm) the emission intensity for low Tb concentrations is mainly governed by the absorption of the incident radiation. With electron excitation, the energy loss of incoming electrons to "killer sites'' in the lattice is found to influence the emission. The ratio, however, of 5D4 to 5D3 intensity is independent of the excitation mode. This ratio tends to a constant value at low concentrations and increases strongly with increasing concentration. These effects are explained by feeding of the 5D3 and 5D4 states from 5d levels, followed by cross relaxation, i.e., 5D3 to 5D4 excitation transfer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.334821
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  • 2
    Electronic Resource
    Electronic Resource
    Sharp boron spikes in silicon grown by fast gas switching chemical vapor deposition (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 711-713 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Boron-doping spikes in Si have been grown by fast gas switching chemical vapor deposition at 800 or 850 °C using Si2H6 in 0.03 or 0.1 atm H2, respectively. The B2H6 doping gas was added for 2 s in two ways, viz. during growth, or as a flush while the Si2H6 was interrupted. High-resolution secondary-ion mass spectrometry (HR-SIMS) analysis has revealed the sharpest as-measured SIMS dopant profiles reported for Si grown by deposition from the gas phase. Electrical measurements show the sheet resistivity of the B spikes to be as low as 580 Ω/(D'Alembertian).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104523
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  • 3
    Electronic Resource
    Electronic Resource
    Sharp phosphorus spikes in silicon grown by fast gas-switching chemical vapor deposition at reduced and atmospheric pressure (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 3297-3299 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Sharp phosphorus doping spikes in silicon were grown by fast-gas-switching chemical vapor deposition at temperatures between 800 and 850 °C using disilane and phosphine in 0.03, 0.1, and 1 atm hydrogen carrier gas. The phosphine doping gas was added while growing silicon at a rate of 0.15–0.5 nm/s. High depth resolution secondary ion mass spectrometry measurements have revealed sharp and high concentration dopant profiles. Peak phosphorus concentrations up to 7×1019 cm−3 and a full width at half maximum of 7 nm were obtained. Electrical measurements show that at these concentrations about 40% of the dopant atoms is electrically active in structures grown at 1 atm. Formation of doping tails is shown to be suppressed at atmospheric hydrogen pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105711
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  • 4
    Electronic Resource
    Electronic Resource
    Reconstruction of palaeoceanographic conditions in the South Atlantic Ocean at the last two Terminations based on calcareous dinoflagellate cysts (2000)
    Springer
    International journal of earth sciences 88 (2000), S. 680-693 
    Details
    ISSN: 1437-3262
    Keywords: Key words Calcareous dinoflagellate cysts ; Palaeoceanography ; Late Quaternary ; Glacial Terminations ; South Atlantic Ocean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Despite the increasing interest in the South Atlantic Ocean as a key area of the heat exchange between the southern and the northern hemisphere, information about its palaeoceanographic conditions during transitions from glacial to interglacial stages, the so-called Terminations, are not well understood. Herein we attempt to increase this information by studying the calcareous dinoflagellate cysts and the shells of Thoracosphaera heimii (calcareous cysts) of five Late Quaternary South Atlantic Ocean cores. Extremely high accumulation rates of calcareous cysts at the Terminations might be due to a combined effect of increased cyst production and better preservation as result of calm, oligotrophic conditions in the upper water layers. Low relative abundance of Sphaerodinella albatrosiana compared with Sphaerodinella tuberosa in the Cape Basin may be the result of the relatively colder environmental conditions in this region compared with the equatorial Atlantic Ocean with high relative abundance of S. albatrosiana. Furthermore, the predominance of S. tuberosa during glacials and interglacials at the observed site of the western Atlantic Ocean reflects decreased salinity in the upper water layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310050297
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  • 5
    Electronic Resource
    Electronic Resource
    Persönliches (1965)
    Springer
    International journal of earth sciences 54 (1965), S. 1320-1322 
    Details
    ISSN: 1437-3262
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01820781
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  • 6
    Electronic Resource
    Electronic Resource
    Development of the first meiotic prophase stages in human fetal oocytes observed by light and electron microscopy (1987)
    Springer
    Human genetics 〈Berlin〉 77 (1987), S. 223-232 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of the first meiotic prophase stages was studied in two series of human female embryos and fetuses aborted for social reasons. The first series (64 embryos or fetuses aborted at 6–24 weeks of gestation) was used mainly to perfect the methods applied to obtain chromosome preparations and synaptonemal complex spreads. The second series (37 embryos or fetuses aborted at 9–24 weeks of gestation) was used to establish the timing and to charcterize the different stages of prophase I. Leptotene-zygotene figures were observed in some embryos at 10 weeks of gestation. Typical zygotene figures were seen at 11–22 weeks. Pachytenes were first observed at 12–13 weeks, and the proportion of these figures was usually lower than 40%. Diplotenes were seen in fetuses with a gestational age of 14 weeks or more. The duration of the process in the human female is thus about 3–4 weeks, a similar period to that described for the male.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00284474
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  • 7
    Electronic Resource
    Electronic Resource
    Localization of SCP2 and SCP3 protein molecules within synaptonemal complexes of the rat (1998)
    Springer
    Chromosoma 107 (1998), S. 540-548 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract.  SCP2 and SCP3 are major protein components of the lateral elements (LEs) of synaptonemal complexes (SCs) of the rat, with M rs of 173,000 and 30,000. We performed a detailed immunocytochemical comparison of the localization of SCP2 and SCP3 within SCs at the electron microscopic level. The ultrastructural localization of SCP2 and SCP3 was analyzed by immunogold labeling of two types of preparations, namely surface-spread spermatocytes and ultrathin sections of Lowicryl-embedded testicular tissue of the rat. For each of the antisera used, the distribution of immunogold label over SCs in surface-spread spermatocytes differed significantly from the distribution of label on sections. We attributed this difference to artifacts caused by the surface-spreading technique, and therefore we relied on sections for the precise localization of epitopes. On sections, the distribution of label obtained with two antisera against nonoverlapping, widely separated fragments of SCP2 did not differ significantly. There was a small but significant difference between the labeling pattern obtained with an anti-SCP3 serum and the pattern obtained with either of the two antisera against fragments of SCP2; although for all three antisera the peak of the immunogold label coincided with the center of the LE, the distributions of label obtained with the antisera against fragments of SCP2 were asymmetrical, with a shoulder at the inner side of the LE, whereas the distribution of label obtained with anti-SCP3 serum was symmetrical. Furthermore, we observed fuzzy connections between the LEs that were labeled by anti-SCP2 but not anti-SCP3 antibodies. It is possible that labeling of these fuzzy bridges caused the shoulder in the gold label distributions obtained with anti-SCP2 antibodies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004120050340
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  • 8
    Electronic Resource
    Electronic Resource
    Em-tomography of section collapse, a non-linear phenomenon (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 31 (1995), S. 311-316 
    Details
    ISSN: 1059-910X
    Keywords: EM-tomography ; Reconstructions ; Back projection ; Section collapse ; Distortion of Z dimensions ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Using back projection for reconstruction and tilt series of Epon or Lowicryl embedded and sectioned material, we demonstrated: (1) a reduction in thickness of 50% for Epon and 80% for Lowicryl sections, and (2) a non-uniform density distribution along the electron-optical axis in sections. The highest density was found at the vacuum exposed side of the section. The formvar side of the section showed a similar increase in density, but not to the same extent. Minimalization of electron exposure, even without pre-exposure, did not affect the reconstructed thickness, nor did it affect the non-uniform density distribution. However, parallax measurements showed that at 150K, collapse of Epon sections does not take place. For EM-tomography of plastic embedded material our findings imply that at the top and bottom portion of the sections the dimensions of the reconstructed structures are distorted, but that in the middle portion the dimensions are reliably retained. © 1995 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070310409
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  • 9
    Electronic Resource
    Electronic Resource
    Localized vibrations in GaP doped with Mn or As (1973)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 1 (1973), S. 109-115 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Raman lines in GaP doped with Mn (0.1 at %) or As (up to 10 at %) are reported and discussed. In GaP-Mn an impurity mode is found which also is observed in the low temperature luminescence. In GaP-As five additional lines are seen. From the identification and relative intensities of these lines conclusions are drawn concerning the clustering of As ions around Ga ions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250010110
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  • 10
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    The inhibition of antigen-presenting activity of dendritic cells resulting from UV irradiation of murine skin is restored by in vitro photorepair of cyclobutane pyrimidine dimers (1997)
    National Academy of Sciences
    Details
    Publication Date: 1997-05-13
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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