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  • 1
    Electronic Resource
    Electronic Resource
    Microscopic shifts of size-assigned p-cresol/H2O-cluster spectra (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 1717-1723 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: p-cresol and its complexes with H2O and CH3OH were cooled in a pulsed supersonic free jet and studied by resonant multiphoton ionization with time-of-flight mass analysis. Detailed mass and concentration analysis allowed an unambiguous assignment of cluster size. The electronic origins of p-cresol (H2O)1,2,3 show irregular red- and blueshifts with change of cluster size, which is referred to the bivalent role of p-cresol as proton donor and acceptor. Ab initio and semiempirical quantum chemical calculations support this interpretation and show the spectral shifts to be essentially due to the inductive effect of the solvent molecules Y exerted on X in X-H...Y. While the vibronic bands of p-cresol (H2O)2 are quite broad, those of p-cresol (H2O)3 are sharp again. The ab initio calculations show that this may be attributed to the quite rigid "open cyclic'' structure of p-cresol (H2O)3. Our experimental and theoretical investigations show a completely analogous behavior of phenol (H2O)1,2,3 clusters
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459944
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  • 2
    Electronic Resource
    Electronic Resource
    Preparation and characterization of CeO2-based superconducting field effect transistors (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 8146-8149 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: High-Tc superconducting field effect transistors using CeO2 as the dielectric layer in combination with ultrathin YBa2Cu3O7−δ layers have been prepared and investigated. The preparation process of these devices is described in detail. CeO2 is very compatible with ultrathin YBa2Cu3O7−δ layers, resulting in Tc values consistent with SrTiO3-based superconducting field effect transistors. The dielectric constant and the breakdown field of the CeO2 layer are reproducible in all investigated samples, yielding values for εr≈20 and Ebd≈2×108 V/m. This results in a charge transfer of ΔN=±2 μC/cm2. In the charge carrier enhancement mode this value is close to SrTiO3-based superconducting field effect transistors. So far, the maximum achieved modulation of the charge carrier density by the use of CeO2 as dielectric is 1.5%. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357865
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  • 3
    Electronic Resource
    Electronic Resource
    YBa2Cu3O7 Josephson junctions and dc SQUIDs by mechanically induced growth disorder (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 3220-3222 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A simple and reproducible method for the fabrication of high-Tc Josephson junctions and SQUIDs is presented. A very weak disturbance is produced by pressing a diamond needle onto the substrate surface before film deposition. The junction parameters such as the critical current Ic, the IcRn product, or β=2IcL/Φ0 (with L the self-inductance of the SQUID loop) are accessible by controlling the film thickness and can be varied by several orders of magnitude. The junctions usually have critical current densities jc in the range of 5×104–1×105 A/cm2 at 77 K and show Shapiro steps when exposed to rf power. The current-voltage characteristics are resistively shunted junctionlike and nonhysteretic. In dc SQUIDs a maximum peak-to-peak voltage response to dc flux of up to 12 μV at 77 K is observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357513
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  • 4
    Electronic Resource
    Electronic Resource
    High-superconducting critical current densities in YBa2Cu3O7/PrBa2Cu3O7 superlattices (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 1626-1628 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Well-ordered [(YBa2Cu3O7)nY/(PrBa2Cu3O7)nPr)]m superlattices with high superconducting critical temperatures were prepared by sequential reactive dc sputtering. The superconducting critical current density at 4.5 K reaches values as high as 1.1×107 A/cm2 for a sample with nY = 2 and nPr = 1 and 3.8×106 A/cm2 for nY = 1 and nPr = 3, indicating that the coupling of the CuO2 layers is not necessary for high-jc values. The angular dependence jc(cursive-phi) is determined by the component of the magnetic field perpendicular to the a-b planes and shows that these superlattices are two-dimensional systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.106251
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  • 5
    Electronic Resource
    Electronic Resource
    CeO2: An alternative insulator material for superconducting field effect devices (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 1871-1873 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The properties of high-Tc superconducting field-effect devices using CeO2 as an insulating layer have been studied. The dielectric constant and hence the achieved charge transfer for constant gate voltage and equivalent geometry is smaller as compared to the established SrTiO3 dielectric. This is mostly compensated by better insulating properties. The observed field effects for a fixed amount of charge transfer are very similar to those obtained with the SrTiO3 dielectric, indicating that the observed field effects are truly due to changes in the charge carrier density and not due to field-induced stresses in the multilayer structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.111783
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  • 6
    Electronic Resource
    Electronic Resource
    New synthesis of aryl-substituted sulfonium salts and their applications in photoinitiated cationic polymerization (1990)
    s.l. : American Chemical Society
    Chemistry of materials 2 (1990), S. 732-737 
    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/cm00012a027
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  • 7
    Electronic Resource
    Electronic Resource
    Immunolocalization of urokinase-type plasminogen activator in adenomas and carcinomas of the colorectum (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Histopathology 19 (1991), S. 0 
    Details
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Carcinogenesis in the human colon is associated with a marked increase in the tissue content of the urokinase-type plasmmogen activator (u-PA). This study was performed to determine the type of cells responsible for the u-PA increase in carcinomas of the colon and in their precursor lesions, the adenomas, by immunohistological evaluation applying monoclonal antibody 3689 directed to the β-chain of u-PA.Normal intestinal mucosa (n= 17) showed hardly any staining of u-PA, but some lamina propria cells were faintly positive. Carcinomas (n= 17) and adenomas (n= 16) showed a considerable and comparable staining intensity of u-PA in neoplastic columnar epithelial cells, and this staining was found to be diffuse and cytoplasmic. In a majority of the neoplastic tissues the u-PA staining was found to be patchy and not related to known risk markers of malignancy such as dysplasia in the adenomas, or to prognostic determinants such as Dukes' classification or differentiation in the carcinomas. The observation of strong u-PA positive lamina propria cells in adenomas but infrequently observed in normal mucosa and carcinomas was noteworthy. u-PA staining intensity of the tissue sections was found to correlate well with the u-PA antigen level in the tissue extracts determined by ELISA (r= 0.52, P= 0.0001) but poorly with the u-PA activity determined enzymatically (r= 0.28, P= 0.05).In conclusion, the u-PA increase in neoplasia of the human colon can be attributed to an increased diffuse cytoplasmic content of u-PA in neoplastic columnar epithelial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2559.1991.tb00027.x
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  • 8
    Electronic Resource
    Electronic Resource
    Lymphocyte subsets, sIL2-R and sICAM-1 in blood during allergen challenge tests in asthmatic children (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Pediatric allergy and immunology 4 (1993), S. 0 
    Details
    ISSN: 1399-3038
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In order to study cell activation in peripheral blood on bronchial allergen provocation up to 24 h, we investigated 32 asthmatic children, sensitive to house-dust mites. Six healthy young adult volunteers served as controls. Lymphocyte subsets (CD3, CD19, CD4, CDS) and activation markers (CD25-T, HLADR-T, CD23) in peripheral blood as well as soluble IL2-R and soluble ICAM-1 in scrum were evaluated. In terms of clinical reaction, 23 children exhibited a DAR, 6 an EAR, 6 a LAR and 3 children did not show a bronchoconstrictor response to allergen challenge with house-dust mite extract (NAR). In comparison to controls, asthmatic children showed a significantly higher expression of CD23 on B-lymphocytcs (p 〈 0.05). Other subsets were in the same range in both groups. After provocation there was a significant increase of CD4/CD8-ratio only in asthmatic children. Serum levels of sIL2-R were significantly higher in asthmatic children compared to controls at baseline as well as at 12 and 24 h after provocation, without variation during observation period, No differences were noted for SICAM-1. Our results confirm the hypothesis that lymphocytes, as important cells in regulation of allergic immune response, are recruited into peripheral blood under allergen challenge conditions in sensitized asthmatic children.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3038.1993.tb00093.x
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  • 9
    Electronic Resource
    Electronic Resource
    Yeast dsRNA viruses: replication and killer phenotypes (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 5 (1991), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The cytoplasmic L-A dsRNA virus of Saccharomyces cerevisiae consists of a 4.5kb dsRNA and the two gene products it encodes: the capsid (cap) and at least one copy of the capsid–polymerase (cap–pol) fusion protein. Virion cap–pol catalyses transcription of the plus (sense)-strand; this is extruded from the virus and serves as messenger for synthesis of cap and cap–pol. Nascent cap–pol binds to a specific domain in the plus strand to initiate encapsidation and then catalyses minus-strand synthesis to complete the replication cycle. Products of at least three host genes are required for replication, and virus copy number is kept at tolerable levels by the SKI antivirus system. S. cerevisiae killer viruses are satellite dsRNAs that use a similar encapsidation domain to parasitize the L-A replication machinery. They encode precursors of secreted polypeptide toxins and immunity (specific resistance) determinants and are self-selecting. Three unique killer types, K1, K2 and K28, are currently recognized. They are distinguished by an absence of cross-immunity and by toxin properties and lethal mechanisms; while K1 and K2 toxins bind to cell-wall glucan and disrupt membrane functions, K28 toxin binds to mannoprotein and causes inhibition of DNA synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1991.tb02078.x
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  • 10
    Electronic Resource
    Electronic Resource
    Twenty-four-hour time course of eosinophil granule proteins ECP and EPX during bronchial allergen challenges in serum of asthmatic children (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Allergy 49 (1994), S. 0 
    Details
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: To study in vivo monitoring variables for bronchial allergen challenges, we investigated the time course of the eosinophil granule proteins, eosinophil cationic protein (ECP) and eosinophil protein × (EPX) after allergen provocation in serum. Thirty-two asthmatic children sensitive to house-dust mites and six healthy young adult controls were challenged by bronchial allergen provocations with Dermatophagoides pteronyssinus and D. farinae. Blood samples were taken at regular intervals up to 24 h. Base-line concentrations of ECP (P〈0.004), EPX (P〈0.002), and eosinophils (P〈0.001) were found to be increased in asthmatic children, as compared with healthy controls. ECP and EPX concentrations showed a uniform pattern with two characteristic features: 1) a rapid increase for both mediators up to 30 min after provocation over base-line values (P〈0.0001 and P〈0.001), followed by a rapid decrease nearly to base-line values in the next 30 min; and 2) a steady increase for ECP and EPX up to 10 h (P〈0.02 and P〈0.01), and even higher levels at 24 h, after challenge (P〈0.002 and P〈0.003). We conclude that although eosinophils are activated in asthmatic children after bronchial allergen challenge, ECP and EPX concentrations are not suitable monitoring variables. Base-line eosinophils seem to predict the occurrence of a late-phase asthmatic reaction after allergen provocation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1398-9995.1994.tb00803.x
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