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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 1975-1977 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A promising technique capable of performing localized resistance measurements over a surface is presented using a modified commercial atomic force microscope with a conducting probe. Its overall purpose is to obtain simultaneous cartographies of surface roughness and local resistance within a given microscopic area of a sample with nanometer scale resolution. Although an elaboration of suitable probes remains an ongoing problem, convincing images of some metal surfaces that reveal occasionally surprising features have already been obtained. Calculations performed from measurements have allowed us to clarify the mechanical nature of the tip/surface nanocontact and hence to determine the most probable transport process according to the range of resistance considered. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 1-10 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A two-dimensional model for hydrogen pair exchange in transition metal trihydrides is used to interpret NMR data observed for [cp(PPh3)IrH3]+. Inspired by quantum chemical results for [cp(PH3)IrH3]+, the model describes a combined process of rotational tunneling and IrH2 bending that merges into an H2 "lift-off'' motion at a small proton–proton distance. The condensed environment with which the tunneling system interacts is represented by a heat bath. A second-order perturbation treatment yields a master equation for the populations of the vibrational states within each of the rotational symmetry species A and B and for the respective AB coherences. A theoretical basis is provided for the evolution of the tunneling (AB) coherence as a damped oscillation in agreement with an independent treatment very recently published by Szymanski [J. Chem. Phys. 104, 8216 (1996)]. A simplified model assumption, containing one adjustable parameter, is made for the system–bath interaction. The temperature-dependent frequency of the tunneling process is found to be close to the Boltzmann average of the tunnel frequencies in the individual vibrational states. Both the calculated temperature-dependent coherence damping-rate constant and the tunnel frequency fit the experimental data after adjustment of three parameters describing the potential energy surface and of the parameter representing the system–bath interaction strength. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 99 (1995), S. 13088-13093 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1424
    Keywords: Key words: Potassium channel — Melanoma —Ether à go-go channel — Intracellular Ca2+— Proliferation — Patch clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. Ion channels and intracellular Ca2+ are thought to be involved in cell proliferation and may play a role in tumor development. We therefore characterized Ca2+-regulated potassium channels in the human melanoma cell lines IGR1, IPC298, and IGR39 using electrophysiological and molecular biological methods. All cell lines expressed outwardly rectifying K+ channels. Rapidly activating delayed rectifier channels were detected in IGR39 cells. The activation kinetics of voltage-gated K+ channels in IRG1 and IPC298 cells displayed characteristics of ether à go-go (eag) channels as they were much slower and depended both on the holding potential and on extracellular Mg2+. In addition, they could be blocked by physiological concentrations of intracellular Ca2+. In accordance with these electrophysiological results, analysis of mRNA revealed the expression of a gene coding for h-eag1 channels in IGR1 and IPC298 cells, but not in IGR39 cells. At elevated Ca2+ concentrations various types of Ca2+-activated K+ channels with single-channel characteristics similar to IK and SK channels were detected in IGR1 cells. The whole-cell Ca2+-activated K+ currents were not voltage dependent, insensitive for 100 nm apamin and 200 μm d-tubocurarine, but were blocked by charybdotoxin (100 nm) and clotrimazole (50 nm). Analysis of mRNA revealed the expression of hSK1, hSK2, and hIK channels in IGR1 cells.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-203X
    Keywords: Prunus persica ; Somaclonal variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Peach [Prunus persica (L.) Batsch] regenerants from cv ‘Sunhigh’ embryo no. 156, regenerants obtained from cv ‘Redhaven’ embryo no. 30, and two peach cultivars ‘Sunhigh’ and ‘Redhaven’, were screened for polymorphic RAPD (Random Amplified Polymorphic DNA) markers with up to 60 10-mer primers. Although 35 primers produced results with scoreable bands, only 10 of the primers revealed polymorphism for regenerants of embryo no. 156 and cv ‘Sunhigh’, and 1 revealed a low level of polymorphism for regenerants of embryo no. 30 and cv ‘Redhaven’. This study demonstrates the feasibility of using RAPD markers to identify somaclonal variants of peach and provides evidence for the existence of genetic differences among these variants.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-203X
    Keywords: Key wordsPrunus persica Somaclonal variation ; AbbreviationsPCR Polymerase chain reaction ; RAPD random amplified polymorphic DNA ; RFLP Restriction fragment length polymorphism ; CTAB cetyltrimethyl ammonium bromide ; PVP polyvinyl pyrolidone ; dNTP deoxy-ribonucleotide triphosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Peach [Prunus persica (L.) Batsch] regenerants from cv `Sunhigh' embryo no. 156, regenerants obtained from cv `Redhaven' embryo no. 30, and two peach cultivars `Sunhigh' and `Redhaven', were screened for polymorphic RAPD (Random Amplified Polymorphic DNA) markers with up to 60 10-mer primers. Although 35 primers produced results with scoreable bands, only 10 of the primers revealed polymorphism for regenerants of embryo no.156 and cv `Sunhigh', and 1 revealed a low level of polymorphism for regenerants of embryo no. 30 and cv `Redhaven'. This study demonstrates the feasibility of using RAPD markers to identify somaclonal variants of peach and provides evidence for the existence of genetic differences among these variants.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 99 (1999), S. 859-867 
    ISSN: 1432-2242
    Keywords: Key words Solanaceae ; Microsatellite ; Simple sequence repeat ; Chloroplast genome ; PCR-based markers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  PCR-based markers were developed from mononucleotide simple-sequence repeats in the chloroplast genome of Nicotiana tabacum and applied to the analysis of genetic diversity. These markers were found to detect high levels of polymorphism at three taxonomic levels in Solanaceous plants. Of 36 chloroplast loci examined, 26 show some degree of polymorphism among potato accessions. Among a set of 30 tetraploid potato cultivars it is apparent that a single chloroplast haplotype is prevalent, presumably a result of the widespread use as a female parent of the imported US cultivar Rough Purple Chili in the latter half of the 19th century. Nonetheless, there is considerable chloroplast diversity in the cultivated potato, and it is clear that a large proportion of this variability has arisen through the use of wild or primitive cultivated species of potato in introgression programmes. This variability should be used in future breeding programmes. An examination of single accessions from 24 potato species, as well as representatives from tobacco and other members of the Solanaceae, reveals high levels of inter-specific chloroplast DNA variation. These data, and the ease of use and potential for multiplexing of these markers, suggest that cpSSRs will be of great utility in population genetics, germplasm management, evolutionary and phylogenetic studies as well as in, the analysis of material from introgression and somatic-fusion experiments. Interestingly, the polymorphism arising from one of the more-polymorphic chloroplast loci examined, does not originate solely from the SSR, and is due to variation in the copy number of two tandemly arrayed sequence elements.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Der Pathologe 17 (1996), S. 130-132 
    ISSN: 1432-1963
    Keywords: Schlüsselwörter Notox ; Formalinersatz ; Histologie ; Key words Notox ; Formaldehyde substitute ; Histology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary “NoToX Histological Fixative” is a formaldehyde substitute for the fixation of tissues prior to histological investigation. Intraoperative samples and necropsy tissue were tested. NoToX was substituted for formaldehyde in the fixation step, otherwise the same manufacturer-specified protocols were used for all reagents. Conventional histological and accepted immunohistological investigations, especially for tumour diagnosis, were used. In all tests, results with NoToX-fixated tissue were similar to those with tissue fixed with formaldehyde regarding both staining and diagnosis. NoToX is a useful substitute for formaldehyde.
    Notes: Zusammenfassung „NoToX Histological Fixative“ wird als Ersatzstoff für Formalin/Formaldehyd zur Fixierung von Gewebeproben für histologische Untersuchungen angeboten. Intraoperative Gewebe- und autoptisch gewonnene Organproben wurden zur Testung von NoToX eingesetzt. Die Fixierung erfolgte nach der angegebenen Vorschrift. Konventionelle histologische Färbungen und akzeptierte immunhistologische Färbungen, insbesondere zur Tumordiagnostik, wurden eingesetzt. Im Ergebnis dieser unabhängig an 3 verschiedenen Einrichtungen durchgeführten Untersuchungen konnte festgestellt werden, daß mit NoToX fixierte Gewebeproben bezüglich der Reproduzierbarkeit der konventionellen Färbungen bzw. der Sichtbarmachung immunhistochemischer Reaktionen keinerlei Unterschiede zu formalinfixierten Gewebeproben aufweisen. NoToX hat sich als brauchbarer Ersatzstoff für Formalin bewährt.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1920
    Keywords: Key words Brain ; blood flow ; Cerebral blood volume ; Magnetic resonance imaging ; Acetazolamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstracts The acetazolamide (ACZ) test is performed to evaluate the decrease in cerebral perfusion pressure (CPP) by investigation of vasomotor reactivity (VMR). Our aim was to study cerebral blood flow and blood volume changes induced by the ACZ test in healthy control subjects using dynamic susceptibility contrast-enhanced gradient-echo MRI (DSC-MRI). A FLASH sequence was used to produce susceptibility-weighted images during an intravenous injection of 0.1 mmol/kg gadopentetate dimeglumine (Gd-DTPA). After the first dynamic study, 1 g acetazolamide was given intravenously and 10 min later a second bolus of Gd-DTPA was injected. Using the indicator-dilution theory, relative cerebral blood volume and relative cerebral blood flow were estimated. In healthy subjects the ACZ test induced a significant increase in relative blood volume (from 80.5 ± 10.7 to 113.4 ± 11.9) and relative blood flow (from 5.73 ± 0.96 to 7.5 ± 0.97), symmetrically in the cerebral hemispheres. This approach might be promising in the understanding of cerebral haemodynamics in patients with vascular disorders.
    Type of Medium: Electronic Resource
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