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  • 1
    Electronic Resource
    Electronic Resource
    Comparative study on dry oxidation of heteroepitaxial Si1−xGex and Si1−x−yGexCy on Si(100)+ (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 1857-1866 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The goal of this study is to investigate the effect of carbon incorporation upon thermal oxidation of Si1−xGex alloys and its role on strain compensation in Si1−xGex alloys. Si1−xGex and Si1−x−yGexCy alloys on Si(100) are grown by combined ion and molecular beam deposition and are then oxidized at 1000 °C in a dry oxygen ambient for two h. The thickness and the composition of all samples before and after oxidation are measured by Rutherford backscattering spectrometry (RBS) combined with ion channeling at 2.0 MeV and carbon nuclear resonance analysis at 4.3 MeV using 4He++ ions. In agreement with previously reported results of dry oxidation on Si1−xGex thin films, 2.0 MeV RBS analysis shows that a layer of SiO2 is formed on the top surface of both Si1−xGex and Si1−x−yGexCy thin films, while Ge segregates towards the top surface and at the SiO2/Si1−xGex and SiO2/Si1−x−yGexCy interfaces. However, it is observed for the first time that dry oxidation rates of Si1−xGex thin films decrease with increasing Ge fraction x for x(approximately-greater-than)0.20 and with increasing minimum yield. Ion channeling analysis and strain measurements indicate that the incorporation of C rather than the amount of C itself affects the dry oxidation mechanism because of its strong influence on film strain and crystalline quality. These results are discussed in conjunction with observations by secondary ion mass spectrometry, high resolution transmission electron microscopy, Fourier transform infrared spectrometry, and tapping mode atomic force microscopy. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362998
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  • 2
    Electronic Resource
    Electronic Resource
    The onset of secondary phase precipitation during synthesis of heteroepitaxial Si1−x−yGexCy on Si(100) (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 782-784 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An upper temperature limit of 450 °C has been established for growth of heteroepitaxial Si1−x−yGexCy solid solutions with substitutional C on Si(100) by combined ion and molecular beam deposition (CIMD). At 450 °C infrared absorption spectroscopy shows that C is on substitutional sites and no SiC precipitates are detected, whereas at 560 °C the substitutional C signal is much smaller but SiC precipitates are still not detected. High resolution transmission electron microscopy shows that Si1−x−yGexCy films deposited at 560 °C exhibit Ge deficient, coherent, secondary phase clusters in the cubic diamond matrix, which are not seen in films deposited at 450 °C. These observations suggest that the clusters are C-rich, Ge-deficient precursors to SiC, with a lattice which is distorted but free of extended defects. Ion channeling results indicate that the Si1−x−yGexCy films might have a distribution of different bond lengths. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116531
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  • 3
    Electronic Resource
    Electronic Resource
    Indicators of discontinuous technological change: an exploratory study of two discontinuities in the machine tool industry (1997)
    Oxford, UK and Boston, USA : Blackwell Publishers Ltd
    R & D management 27 (1997), S. 0 
    Details
    ISSN: 1467-9310
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: The objective of this paper is to explore the extent to which a set of indicators of technological and industrial change can act as warning signals for technical change. A particular kind of technical change can give a new substitute such price/performance attributes that it is taken into the reach of mass market segments. Two processes of discontinuous technical change in the machine tool industry are analysed using patent data, bibliometrics, data on new entrants, relative price changes and diffusion data. In the first case (the transition from conventional to CNC machine tools) relative prices and new entrants were the first indicators to react whilst patents and bibliometrics increased in activity in parallel with the large scale diffusion of CNC machine tools. In the second case (the transition from CNC machine tools to flexible manufacturing systems) new entrants and publishing preceded the large scale diffusion by some years. The different patterns between the two cases and between these and what can be found in the literature, suggest that more work needs to be done to understand the conditions under which changes in each of the indicators can be used as a warning signal. The paper is concluded by a brief discussion which may form the basis for some further work in that direction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1467-9310.00048
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  • 4
    Electronic Resource
    Electronic Resource
    Heteroepitaxial properties of Si1−x−yGexCy on Si(100) grown by combined ion- and molecular-beam deposition (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 3081-3091 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The heteroepitaxial growth of the new ternary, group-IV, semiconductor material, Si1−x−yGexCy on Si(100), has been investigated. The epitaxial quality of Si1−x−yGexCy is found to be inferior to that of Si1−xGex with similar Si/Ge concentration ratio, grown under identical conditions, and the quality deteriorates with increasing C fraction. Also, the surface roughness, as studied by tapping mode atomic force microscopy, increases with increasing C fraction as well as with increasing Ge fraction, suggesting a transition from Frank–van der Merwe to Stranski–Krastanov type growth. We suggest that the very large mismatch between the average bond length in the Si1−x−yGexCy material, as determined by Vegard's law, and the equilibrium Si(Single Bond)C bond length, weakens the Si(Single Bond)C bonds and reduces the elastic range of the material, thus lowering the barrier for dislocation and stacking fault formation. The change in elasticity may also be responsible for the change in growth morphology, either directly by a lowered barrier for island formation or indirectly through the formation of defects. A decrease in Ge incorporation in the Si1−x−yGexCy films with increasing C incorporation suggests a repulsive Ge–C interaction. Moreover, we observe a C-rich, Ge-deficient precursor phase to SiC precipitates at a growth temperature of 560 °C, whereas at 450 °C no such phase can be observed. The temperature dependence of the precursor formation is consistent with C bulk diffusion. Infrared absorption measurements cannot be used to detect the precursor phase. Finally, the onset of epitaxial breakdown is discussed and an accurate and independent determination of the C fraction and its substitutionality is emphasized. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.364352
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  • 5
    Electronic Resource
    Electronic Resource
    Functional conservation of the effector protein translocators PopB/YopB and PopD/YopD of Pseudomonas aeruginosa and Yersinia pseudotuberculosis (1998)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 29 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Virulent Yersinia species cause systemic infections in rodents, and Y. pestis is highly pathogenic for humans. Pseudomonas aeruginosa, on the other hand, is an opportunistic pathogen, which normally infects only compromised individuals. Surprisingly, these pathogens both encode highly related contact-dependent secretion systems for the targeting of toxins into eukaryotic cells. In Yersinia, YopB and YopD direct the translocation of the secreted Yop effectors across the target cell membrane. In this study, we have analysed the function of the YopB and YopD homologues, PopB and PopD, encoded by P. aeruginosa. Expression of the pcrGVHpopBD operon in defined translocation-deficient mutants (yopB/yopD ) of Yersinia resulted in complete complementation of the cell contact-dependent, YopE-induced cytotoxicity of Y. pseudotuberculosis on HeLa cells. We demonstrated that the complementation fully restored the ability of Y. pseudotuberculosis to translocate the effector molecules YopE and YopH into the HeLa cells. Similar to YopB, PopB induced a lytic effect on infected erythrocytes. The lytic activity induced by PopB could be prevented if the erythrocytes were infected in the presence of sugars larger than 3 nm in diameter, indicating that PopB induced a pore of similar size compared with that induced by YopB. Our findings show that the contact-dependent toxin-targeting mechanisms of Y. pseudotuberculosis and P. aeruginosa are conserved at the molecular level and that the translocator proteins are functionally interchangeable. Based on these similarities, we suggest that the translocation of toxins such as ExoS, ExoT and ExoU by P. aeruginosa across the eukaryotic cell membrane occurs via a pore induced by PopB.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00994.x
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  • 6
    Electronic Resource
    Electronic Resource
    Mice lacking mitochondrial uncoupling protein are cold-sensitive but not obese (1997)
    [s.l.] : Macmillan Magazines Ltd
    Nature 387 (1997), S. 90-94 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The Ucp gene was inactivated by homologous recombination in embryonic stem cells (ES) with a targeting vector that replaced a BamH11Bg111 fragment carrying exon 2 and part of exon 3 with the neor gene, thereby deleting an essential membrane- ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/387090a0
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  • 7
    Electronic Resource
    Electronic Resource
    A Raman study of polymerised C60 (1997)
    Springer
    Applied physics 64 (1997), S. 223-226 
    Details
    ISSN: 1432-0630
    Keywords: PACS: 61.46.+w; 78.30.-J
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: 60 are reported. Although prepared according to different routes the Raman spectra of the two polymeric phases of C60 show a quantitative agreement with respect to mode positions and intensity. We conclude from this that both materials have the same structure at least in the short range order, i.e. the same type of bonding and co-ordination between neighbouring C60 molecules. An investigation of the time dependence of the thermal decomposition of high pressure polymerised C60 is also presented. The rate of decomposition of the polymeric phase is found to be multi-exponential at all temperatures investigated. From an Arrhenius-type analysis of the short time data and the long time data, respectively, the activation energy for thermal dissociation of polymeric bonds was found to increase with time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003390050470
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  • 8
    Electronic Resource
    Electronic Resource
    Exocytotic proteins in enterochromaffin-like (ECL) cells of the rat stomach (1997)
    Springer
    Cell & tissue research 290 (1997), S. 539-551 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Exocytotic proteins ; Synaptophysin ; Synaptotagmin ; Syntaxin ; Secretory granule ; Histidine decarboxylase (HDC) ; Immunohistochemistry ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Proteins participating in vesicular docking and fusion have been identified in the nervous system. Such proteins appear to be important for the molecular regulation of exocytosis also in non-neuronal cells. The enterochromaffin-like (ECL) cells of the gastric acid-secreting (oxyntic) mucosa secrete histamine and chromogranin A-derived peptides, such as pancreastatin. Using immunohistochemistry, we have examined whether the ECL cells of the rat stomach, identified with antibodies to histidine decarboxylase (HDC, the histamine-forming enzyme), express the same exocytotic proteins as neurons. The ECL cells displayed immunoreactivity for synaptophysin, synaptotagmin III, vesicle-associated membrane protein-2 (VAMP-2), cysteine string protein (CSP), vesicular monoamine transporter-2 (VMAT-2), synaptosomal-associated protein of 25 kDa (SNAP-25), syntaxin, and Munc-18, but not for synaptotagmin I/II and VAMP-1. Synaptophysin and VMAT-2 could be detected not only in the ECL cells, but also in a population of HDC-negative cells. The demonstration of synaptotagmin III in only a limited number of ECL cells suggests the existence of a subpopulation of ECL cells. The results show that several exocytotic proteins, previously identified in neurons, are present in rat stomach ECL cells. Hence, proteins engaged in vesicular docking and in the fusion of granule/vesicle membrane with plasma membrane seem to exist in both neurons and endocrine cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050960
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  • 9
    Electronic Resource
    Electronic Resource
    UCP1: The Original Uncoupling Protein—and Perhaps the Only One? New Perspectives on UCP1, UCP2, and UCP3 in the Light of the Bioenergetics of the UCP1-Ablated Mice (1999)
    Springer
    Journal of bioenergetics and biomembranes 31 (1999), S. 475-491 
    Details
    ISSN: 1573-6881
    Keywords: Uncoupling proteins ; nonshivering thermogenesis ; brown-fat mitochondria ; liver mitochondria ; norepinephrine ; mitochondrial membrane potential ; obesity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The availability of a UCP1-ablated mouse has enabled critical studies of the function of UCP1,UCP2, and UCP3. Concerning UCP1, its presence in brown-fat mitochondria is associatedwith innate uncoupling, high GDP-binding capacity, and GDP-inhibitable Cl- permeabilityand uncoupling—but the high fatty acid sensitivity found in these mitochondria is observedeven in the absence of UCP1. The absence of UCP1 leads to low cold tolerance but not toobesity. UCP1 ablation also leads to an augmented expression of UCP2 and UCP3 in brownadipose tissue, making this tissue probably the one that boasts the highest expression ofthese UCPs. However, these very high expression levels are not associated with any inherentuncoupling, or with a specific GDP-binding capacity, or with a GDP-sensitive Cl- permeability,or with any effect of GDP on mitochondrial membrane potential, or with an increased basalmetabolism of cells, or with the presence of norepinephrine- or fatty acid-induced thermogenesisin cells, and not with a cold-acclimation recruited, norepinephrine-induced thermogenicresponse in the intact animal. Therefore, it can be discussed whether any uncoupling effect isassociated with UCP2 or UCP3 when they are endogenously expressed and, consequently,whether (loss of) uncoupling (thermogenic) effects of UCP2 or UCP3 can be invoked toexplain metabolic phenomena, such as obesity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005400507802
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  • 10
    Electronic Resource
    Electronic Resource
    New on-line NMR/ON nuclear magnetic dipole moments near 132Sn: II variation with proton and neutron number: shell model treatment of ‘collective’ effects (1999)
    Springer
    Hyperfine interactions 120-121 (1999), S. 651-655 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Recent on-line nuclear orientation measurements of odd-A nuclear magnetic dipole moments of odd-A Sb, Te and I isotopes by the method of NMR on oriented nuclei mean that we now have complete series of odd-A moments up to, and including, those closest to the double shell closure at 132Sn. In this paper we consider the systematic changes in the measured moments as a function of proton number for the isotonic sequence 133Sb [g7/2+]1–139La [g7/2+]7 and as a function of neutron number for the isotopic sequences 125-133Sb and 127-135I and their interpretation using collective and shell model approaches.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017027707862
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