Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • 2005-2009  (2)
  • 2000-2004  (7)
  • 1990-1994  (21)
  • 1
    Electronic Resource
    Electronic Resource
    Characterization of thin film electron emitters by scanning anode field emission microscopy (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 768-780 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Scanning anode field emission microscopy is used to map the electron emission current I(x,y) under constant anode voltage and the electron extraction voltage V(x,y) under constant emission current as a function of tip position on carbon based thin film emitters. The spatially resolved field enhancement factor β(x,y) is derived from V(x,y) maps. It is shown that large variations in the emission site density (ESD) and current density can be explained in terms of the spatial variation of the field enhancement β(x,y). Comparison of β(x,y) and I(x,y) shows that electron emission currents are correlated to the presence of high aspect ratio field enhancing structures. We introduce the concept of field enhancement distribution f(β), which is derived from β(x,y) maps to characterize the field emission properties of thin films. In this context f(β)dβ gives the number of emitters on a unit surface with field enhancement factors in the interval (β,β+dβ). It is shown experimentally for the carbon thin film emitters investigated that f(β) has an exponential dependence with regard to the field enhancement factor β. The field enhancement distribution function f(β) can be said to give a complete characterization of the thin film field emission properties. As a consequence, the emitted current density and ESD can be optimized by tuning f(β) of the emitting thin film. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1379559
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Dielectric properties of cement mortar as a function of water content (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 71 (1992), S. 5897-5903 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the dielectric properties of cement mortars, with water/cement ratios between 0.5 and 0.78, in the frequency range 10−3≤f≤107 Hz. The dielectric response can be modeled by an equivalent circuit incorporating electrode polarization and bulk conduction. The bulk dc conductance and the amplitude of a constant phase element describing the dispersive part of the bulk response display characteristic dependencies on the water content of the samples. The power-law exponent of the constant phase element is independent of water content and can be related to the fractal dimension of the pore surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350488
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Scanning field emission from patterned carbon nanotube films (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 2071-2073 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The investigation of the field emission (FE) properties of carbon nanotube (CNT) films by a scanning anode FE apparatus, reveals a strong dependence on the density and morphology of the CNT deposit. Large differences between the microscopic and macroscopic current and emission site densities are observed, and explained in terms of a variation of the field enhancement factor β. As a consequence, the emitted current density can be optimized by tuning the density of CNTs. Films with medium densities (on the order of 107 emitters/cm2, according to electrostatic calculations) show the highest emitted current densities. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.126258
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Collective emission degradation behavior of carbon nanotube thin-film electron emitters (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 1036-1038 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The current-induced emission degradation of a carbon nanotube (CNT) thin-film electron emitter is studied under constant emission current for different current levels, using a scanning anode field emission microscope. A permanent emission degradation is observed for emission currents higher than 300 nA per CNT and is associated with resistive heating at the CNT–substrate interface for the sample under investigation. A second field-induced emission degradation mechanism, associated with the removal of CNTs from the substrate, is also reported. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1392982
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The importance of the level of metronidazole resistance for the success of 〈fr〉Helicobacter pylori〈/fr〉 eradication (2004)
    Oxford, UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 19 (2004), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aims : To evaluate the role of antibiotic susceptibility for the treatment outcome of proton pump inhibitor-dependent and independent Helicobacter pylori eradication regimens.Methods : In a placebo-controlled clinical study of peptic ulcer patients with H. pylori infection, patients were randomized to receive lansoprazole, clarithromycin and tinidazole twice-daily, clarithromycin and tinidazole once-daily with lansoprazole or with placebo. Helicobacter pylori status was assessed by culture and antibiotic susceptibility by E-test minimal inhibitory concentration (MIC) in 205 clinical isolates.Results : Primary resistance to clarithromycin and metronidazole was 1 and 76%, respectively. In metronidazole susceptible strains eradication rates were similar at 〉 90% for all treatment groups (P = 0.49). With low-level metronidazole resistance (4 μg/mL 〈 MIC 〈 256 μg/mL), eradication rates were similar at 〉75% (P = 0.80). The major difference was found at high-level metronidazole resistance (MIC ≥ 256 μg/mL) with 95%, 58% and 21% eradication in the lansoprazole, clarithromycin and tinidazole twice-daily, lansoprazole, clarithromycin and tinidazole once-daily and placebo, clarithromycin and tinidazole once-daily groups, respectively (P 〈 0.001).Conclusion : In the absence of antibiotic resistance, a once-daily therapy of only clarithromycin and tinidazole can achieve a high rate of H. pylori eradication. Such a combination could offer a simpler and cheaper treatment option for developing countries. The standard, twice-daily proton pump inhibitor-based triple therapy was shown to be efficient in H. pylori eradication even in the presence of high-level metronidazole resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2036.2004.01959.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Expression of Heterozygous lpr Gene in MRL Mice (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 32 (1990), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Recently we showed that not only homozygous MRL lpr/lpr mice but also heterozygous MRL +/lpr mice display defective antigen- and mitogen-driven T-cell responses as well as polyclonal B-cell activation compared with congeneic MRL +/+ mice. In this study we examined die impact of the heterozygous lpr gene on organ pathology in kidneys, joints, and salivary glands, as well as serum levels of immunoglobulins and autoantibodies in young and old MRL mice. Only 1 out of 17 heterozygous lpr-bearing MRL mice developed clinically overt renal disease with significant proteinuria and haematuria during the first year of life. However, examination of Ig and C3 deposits in glomeruli of kidneys from these mice revealed that the expression of the heterozygous lpr gene in MRL mice accelerates glomerulonephritis in addition, histological examination of the submandibular salivary glands showed an increased focus score in heterozygous MRL mice at 4–5 months of age compared with that of matched congeneic +/+ mice. In contrast, no signs of arthropathy were registered in the heterozygous lpr-bearing MRL mice. Heterozygous MRL mice displayed an expanding lymphoid system as evaluated by significantly increased spleen and lymph node weights com pared with those of matched MRL +/+ mice. Further evidence for immunomodulatory properties of the heterozygous lpr gene was obtained when analysing serum levels of IgG, IgM, and autoantibodies. Thus, heterozygous MRL +/lpr mice produced significantly higher levels of both Ig and autoantibodies than matched MRL +/+ mice. We conclude that the expression of the heterozygous lpr gene in MRL mice results in acceleration of the autoimmune process, giving rise to precocious clinical disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.1990.tb02887.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Quantitative and Qualitative Analysis of Human IgG Subclass Specific mRNA Using Solution Hybridization (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 34 (1991), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Four IgG subclasses have been identified in the human system. Despite the tact that they exhibit differences in their functional properties, antigenic properties and chemical composition and demonstrate age-related shifts in their expression, the genes coding for their constant regions show extensive homology at the nucleotide level (〉 95%). The only parts of the Cγ genes that show significant variation among the different IgG subclasses are the exons coding for their hinge regions (〈 60%). Taking advantage of such sequence variation, we have developed specific RNA probes which allowed us to analyse the expression of the Cγ1. Cγ2, Cγ3 and Cγ4 genes al the mRNA level using solution hybridization. We have defined optimal conditions that allow the detection of picogram levels of IgG subclass specific mRNA, while keeping the cross-reactivity between the different probes below 2%. This approach will significantly facilitate studies aiming at characterizing the molecular mechanisms regulating the expression of the four human IgG heavy chain constant region genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.1991.tb01579.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Quantitative Measurement of the Levels of Melanocortin Receptor Subtype 1, 2, 3 and 5 and Pro-Opio-Melanocortin Peptide Gene Expression in Subsets of Human Peripheral Blood Leucocytes (2005)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Scandinavian journal of immunology 61 (2005), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Levels of the melanocortin receptor (MCR) 1, 2, 3 and 5 subtypes and pro-opio-melanocortin (POMC) protein mRNA were measured by the real-time quantitative reverse transcriptase polymerase chain reaction method in CD4+ T helper (Th) cells, CD8+ T cytotoxic cells, CD19+ B cells, CD56+ natural killer (NK) cells, CD14+ monocytes and CD15+ granulocytes from healthy donors. We found high levels of all of the MC1, 2, 3 and 5R subtype mRNA in Th cells and moderate levels in NK cells, monocytes and granulocytes. POMC peptide mRNA was found in all examined leucocyte subsets, but only low levels were present in granulocytes. Our findings suggest a co-ordinating role for MCR subtypes and their naturally occurring ligands in the co-operation between innate and adaptive immunity. Moreover, our findings are compatible with earlier finding of MCR-mediated tolerance induction in Th cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.2005.01565.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Do early childhood immunizations influence the development of atopy and do they cause allergic reactions? (2001)
    Copenhagen, Denmark : Munksgaard International Publishers
    Pediatric allergy and immunology 12 (2001), S. 0 
    Details
    ISSN: 1399-3038
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Concerns about allergic side-effects of vaccines and about a possible promotion of allergic diseases contribute to incomplete vaccination rates in childhood. This article reviews the current understanding of these issues. There is evidence that pertussis and diphtheria/tetanus antigens elicit immunoglobulin E (IgE) antibody formation as part of the immune response. In murine models, pertussis toxin is an effective adjuvant for IgE formation against simultaneously administered antigens. In children, however, sensitization to unrelated antigens or development of allergic diseases do not seem to be augmented. In contrast, bacille Calmette–Guérin (BCG) and measles vaccination have been proposed as suppressors of allergy because of their T helper 1 (Th1)-fostering properties. In the murine system, BCG inhibits allergic sensitization and airway hyper-reactivity. Some epidemiological studies in humans suggest an inhibitory effect of tuberculosis on allergy. BCG vaccination in children, however, has no or merely a marginal suppressive effect on atopy. Other vaccine components such as egg proteins, gelatin, and antibiotics are a potential hazard to children with severe clinical reactions to these allergens. These rare children should be vaccinated under special precautions. In conclusion, vaccination programs do not explain the increasing prevalence of allergic diseases, but individual children may uncommonly develop an allergic reaction to a vaccine. The risks of not vaccinating children, however, far outweigh the risk for allergy. Therefore, childhood vaccination remains an essential part of child health programs and should not be withheld, even from children predisposed for allergy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3038.2001.1r046.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Radioimmunoassay of human eosinophil cationic protein (ECP) by an improved method. Establishment of normal levels in serum and turnover in vivo (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 21 (1991), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A radio immunoassay was developed allowing measurement of the cytotoxic cationic ECP. The assay, which has a total incubation time of 3.5 hr, is a double antibody assay with radiolabelled ECP. covering the concentration range of 2–200 μ/l. Performance data show a detection limit of 〈 2 μg/1 and a cross-reactivity with eosinophil protein X (EPX/EDN) of 〈0.06%. The coefficient of variation (%) within the measuring range was, within assay 4.8–10.4, and total 6.6–12.0. The assay is useful for measurement in various body fluids including serum, nasal secretions and bronchoalveolar lavage fluid, and dilution of samples prior to analysts was generally not required. Sera from 100 apparently healthy individuals revealed a geometric mean of 6.0 μg ECP/1 and a range (95%) of 2.3–15.9 μg/1. The elimination rate of ECP, t12. in vivo was estimated to be 65 min when ECP was measured in serum. Comparisons between this assay and a method previously described showed that the new method is superior with regard to precision and assay procedure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2222.1991.tb00847.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...