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  • 1
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous hydrogenated carbon (a–C:H) is introduced as a constituent of a two–layer resist system for lithography with a scanning tunneling microscope (STM) operating in air. The resist is made up of a thin electron sensitive and chemically amplified top resist (≤50 nm) and a–C:H as a thick conducting and etchable bottom resist. In this setup the bottom resist acts as the counter electrode allowing in principle operation on insulating substrates. We show that it is possible to generate structures with high aspect ratios by transfering the developed top resist patterns by means of oxygen reactive ion etching (RIE) into the bottom resist and halogen RIE into silicon substrates. Linewidths between 100 and 50 nm have been observed in the bottom resist as well as in the substrates. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 136 (1996), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract NAD-glycohydrolase (NADase) was purified from culture supernatant fluids of group C streptococci by adsorption on silica gel, chromatography on hydroxyapatite and ion exchange on Mono S column. After inactivation of a chymotrypsin-like protease, a homogeneous enzyme was isolated with an N-terminal sequence of VSGKEGKKSDVKYEMTKVMEANATSS-KEDKHVMHTLDKVM. According to serological methods, the purified enzyme of group C streptococci was identical to the group A enzyme showing a specific activity of 10000000 U mg−1. It did not attack NADH, NADP or NADPH. In addition, a streptodornase was isolated having an N-terminal sequence of KTVSVNQTYGE.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2102
    Keywords: Schlüsselwörter MRT ; Funktionelle Bildgebung ; Schnelle Sequenzen ; Schnarchen ; OSA ; Key words MRI ; Functional imaging ; Ultrafast sequences ; Snoring ; Obstructive sleep apnea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Functional imaging of the pharynx used to be the domain of cineradiography, CT and ultrafast CT. The development of modern MRI techniques led to new access to functional disorders of the pharynx. The aim of this study was to implement a new MRI technique to examine oropharyngeal obstructive mechanisms in patients with obstructive sleep apnea (OSA). Sixteen patients suffering from OSA and 6 healthy volunteers were examined on a 1.5 T whole-body imager (“Vision”, Siemens, Erlangen Medical Engineering, Germany) using a circular polarized head coil. Imaging was performed with 2D flash sequences in midsagittal and axial planes. Patients and volunteers were asked to breathe normally through the nose and to simulate snoring and the Mueller maneuver during magnetic resonance imaging (MRI). Prior to MRI, all patients underwent an ear, nose and throat (ENT) examination, functional fiberoptic nasopharyngoscopy and polysomnography. A temporal resolution of 6 images/s and an in-plane resolution of 2.67 × 1.8 mm were achieved. The mobility of the tongue, soft palate and pharyngeal surface could be clearly delineated. The MRI findings correlated well with the clinical examinations. We propose ultrafast MRI as a reliable and non-invasive method of evaluating pharyngeal obstruction and their levels.
    Notes: Zusammenfassung Die funktionelle Bildgebung des Pharynx war bisher eine Domäne der Hochfrequenzröntgenkinematographie, der Computertomographie (CT) und der ultraschnellen Computertomographie. Die Entwicklung moderner Techniken in der Magnetresonanztomographie (MRT) führte zu neuen Ansätzen in der Diagnostik pharyngealer Dysfunktionen. Ziel der vorliegenden Studie war die Implementierung neuer schneller MR-Sequenzen, um Verschlußmechanismen entlang des Pharnyxschlauches bei Patienten mit obstruktiver Schlafapnoe (OSA) zu untersuchen. 16 Patienten mit OSA und 6 gesunde Probanden wurden an einem 1,5-T-Ganzkörpermagnetresonanztomographen („Vision“, Siemens Medizintechnik, Erlangen) mit einer zirkularpolarisierten Kopfspule untersucht. Die Bildgebung erfolgte mit schnellen 2D-FLASH-(Fast-low-angle-shot-) Sequenzen in sagittaler und axialer Schichtführung. Patienten und Probanden führten folgende Atemmanöver während der MRT durch: ruhige Nasenatmung bei geschlossenem Mund, Schnarchsimulation und Müller-Manöver. Vor der MRT unterzogen sich die OSA-Patienten einer HNO-ärztlichen Untersuchung, einer funktionellen flexiblen Nasopharyngoskopie und einer Polysomnographie. Mit der 2D-FLASH-Sequenz wurde eine Bildfolge von 6 Bildern/s und eine Ortsauflösung von 2,67 × 1,8 mm erreicht. Die Bewegungen der Zunge, des weichen Gaumens, der Uvula und der Pharynxwände konnten mit Hilfe der MRT dynamisch wiedergegeben werden. Die Darstellung der erhöhten Kollapsneigung der pharyngealen Weichteile bei den OSA-Patienten gelang ebenfalls mit der MRT. Diese Ergebnisse korrelierten gut mit den Untersuchungen der funktionellen flexiblen Nasopharyngoskopie. Die ultraschnelle MRT scheint als zuverlässige, nichtinvasive Methode zur Diagnostik der OSA geeignet zu sein.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-041X
    Keywords: Key words Drosophila ; Evolutionary conservation ; GAGA factor ; Trithorax-like
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  As a member of the trithorax-group, the Trithorax-like (Trl) gene of Drosophila melanogaster contributes to the expression of homeotic genes and many other genes. Trl encodes different isoforms of the GAGA factor which is thought to act as an ”antirepressor” of transcription by remodelling chromatin structure and thereby rendering control regions accessible for transcriptional activators. A more global role of the GAGA factor in chromatin structure and function is suggested by various phenotypes of Trl mutations, such as modification of position effect variegation. To better define the molecular basis of these pleiotropic effects, we cloned cDNAs encoding the GAGA isoforms of D. melano- gaster and a distantly related species, D. virilis. We also characterized the genomic organization of both the D. melanogaster and D. virilis genes, and analysed the expression patterns of isoform-specific mRNAs. The D. virilis GAGA isoforms show high similarity to their D. melanogaster counterparts, particularly within the BTB/POZ protein-interaction and the zinc finger DNA-binding domains. Interestingly, conservation clearly extends beyond the previously defined limits of these domains. Moreover, the comparison reveals a completely conserved block of amino acid residues located between the BTB/POZ and DNA-binding domains, and a high conservation of the C-terminus specific for one of the GAGA isoforms. Thus, sequences of as yet unknown functions are defined as rewarding targets for further mutational analyses. The high conservation of the GAGA proteins of the two species is in accord with the nearly identical genomic organization and expression patterns of the corresponding genes.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0851
    Keywords: Anti-GD2 antibody ; Cytotoxic T cells ; Immunoconjugate ; Neuroblastoma ; Superantigens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Superantigens such as the staphylococcal enterotoxin A (SEA) are among the most potent T cell activators known. They bind to major histocompatibility complex (MHC) class II molecules and interact with T cells depending on their T cell receptor (TCR) Vβ expression. Superantigens also induce a variety of cytokines and trigger a direct cytotoxic effect against MHC-class-II-positive target cells. In order to extend superantigen-dependent cell-mediated cytotoxicity (SDCC) to MHC-class-II-negative neuroblastoma cells, SEA was linked to the anti-ganglioside GD2 human/mouse chimeric monoclonal antibody (mAb) ch14.18. Ganglioside GD2 is expressed on most tumours of neuroectodermal origin but is expressed to a lesser extent on normal tissues. The linkage of ch 14.18 to SEA was achieved either with a protein-A-SEA fusion protein or by chemical coupling. Both constructs induced T-cell-mediated cytotoxicity towards GD2-positive neuroblastoma cells in an effector-to-target(E∶T)-ratio-and dose-dependent manner in vitro. To reduce the MHC class II affinity of SEA, a point mutation was introduced in the SEA gene (SEAm9) that resulted in 1000-fold less T cell killing of MHC-class-II-expressing cells as compared to native SEA. However, a protein-A-SEAm9 fusion protein mediated cytotoxicity similar to that of protein-A-SEA on ch14.18-coated, MHC-class-II-negative neuroblastoma cells. Taken together, these findings suggest that superantigen-dependent and monoclonal-antibody-targeted lysis may be a potent novel approach for neuroblastoma therapy.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0851
    Keywords: Key words Anti-GD2 antibody ; Cytotoxic T cells ; Immunoconjugate ; Neuroblastoma ; Superantigens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Superantigens such as the staphylococcal enterotoxin A (SEA) are among the most potent T cell activators known. They bind to major histocompatibility complex (MHC) class II molecules and interact with T cells depending on their T cell receptor (TCR) Vβ expression. Superantigens also induce a variety of cytokines and trigger a direct cytotoxic effect against MHC-class-II-positive target cells. In order to extend superantigen-dependent cell-mediated cytotoxicity (SDCC) to MHC-class-II-negative neuroblastoma cells, SEA was linked to the anti-ganglioside GD2 human/mouse chimeric monoclonal antibody (mAb) ch14.18. Ganglioside GD2 is expressed on most tumours of neuroectodermal origin but is expressed to a lesser extent on normal tissues. The linkage of ch14.18 to SEA was achieved either with a protein-A–SEA fusion protein or by chemical coupling. Both constructs induced T-cell-mediated cytotoxicity towards GD2-positive neuroblastoma cells in an effector-to-target(E:T)-ratio-and dose-dependent manner in vitro. To reduce the MHC class II affinity of SEA, a point mutation was introduced in the SEA gene (SEAm9) that resulted in 1000-fold less T cell killing of MHC-class-II-expressing cells as compared to native SEA. However, a protein-A–SEAm9 fusion protein mediated cytotoxicity similar to that of protein-A–SEA on ch14.18-coated, MHC-class-II-negative neuroblastoma cells. Taken together, these findings suggest that superantigen-dependent and monoclonal-antibody-targeted lysis may be a potent novel approach for neuroblastoma therapy.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Biomedical microdevices 2 (1999), S. 61-72 
    ISSN: 1572-8781
    Keywords: biohybrid cell culture ; chick ; neurite growth ; immunocytochemistry ; microphotodiode ; optoelectric stimulation ; retinal implant ; retinitis pigmentosa ; scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Various neurodegenerative diseases of the retina lead to blindness. Since no pharmacological or gene therapy is available, the alternative concept of neuroprostheses has stimulated the development of micromachined photovoltaic devices. One strategy aims to replace degenerated photoreceptors by microphotodiode arrays (MPDA). MPDAs in the subretinal space shall transform light stimuli into electrical current for the stimulation of still unhampered retinal neurons. MPDAs were fabricated as silicon based multilayered PIN microstructures comprising titanium nitride stimulation electrodes of an area of 8 × 8 μm2. In an effort to develop meaningful tools to evaluate functional MPDA biocompatibility, a novel in vitro system was designed. Retinal cells were cultured on MPDAs, while current generation in MPDAs as in the eye was imitated by light emitting diodes (LED) operating at different wavelengths. For analysis epifluorescence and scannning electron microscopy was employed. MPDAs displayed increasing current delivery with increasing illumination. Surface modification of MPDAs including oxygen plasma treatment and adsorption of polyanions together with laminin were found to render the MPDA surface permissive for cell adhesion. Cell vitality tests using fluorescence markers revealed no adverse effects of optoelectric stimulation via LED/MPDAs. In addition, neurite formation and the expression of differentiation antigen 2A10 were unaffected after stimulation. Optoelectric stimulation allowed regular differentiation of various retinal cell types. In summary, the data provide the first evidence that optoelectric stimulation via MPDAs does not hamper cellular integrity under the experimental conditions chosen. The results support the concept of microphotodiodes as a retinal prosthesis.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Microsystem technologies 2 (1996), S. 130-134 
    ISSN: 1432-1858
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Technology
    Notes: Abstract  For the production of microstructured ceramic parts, development efforts are necessary in the field of powder synthesis as well as in the area of shaping. Several processes have been developed. Powder synthesis was performed starting from metal organic precursors and using a two stage thermal process. Shaping was performed by sol-gel methods, by pressing of a ceramic slurry or an organic precursor paste as well as by direct electrophoretic deposition of gels in a microstructured form. An overview is given on the methods and the results.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Microsystem technologies 2 (1996), S. 135-138 
    ISSN: 1432-1858
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Technology
    Notes: Abstract  The developed process of tape casting with subsequent stamping is a promising way to make three-dimensional ceramic microstructures. Examples of different ceramic materials illustrate, that a good quality of the moulding with high form fit can be attained after optimisation of the slurry and the stamping process. The sintered microstructures are characterised by lateral dimensions in the micron range and high aspect ratios. The unique properties of ceramic materials in combination with this new process can be used to produce microstructured ultrasonic transducers or micro heat exchangers/reactors.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1211
    Keywords: Key words MHC ; MIC ; Nonhuman primates ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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