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  • Springer  (95)
  • 2000-2004  (95)
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  • 1
    Electronic Resource
    Electronic Resource
    Intramolecular Alkyne Coupling in the Reaction of 1,8-bis(phenylethynyl)naphthalene with Pt2Ru4(CO)18 (2000)
    Springer
    Journal of cluster science 11 (2000), S. 55-65 
    Details
    ISSN: 1572-8862
    Keywords: bis(phenylethynyl)naphthalene ; ruthenium ; platinum ; alkyne coupling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reaction of Pt2Ru4(CO)18, 1 with 1,8-bis(phenylethynyl)naphthalene, 2 has yielded two metal carbonyl cluster complexes: Ru2(CO)6[μ-η 2-C10H6C4Ph2], 3 (60% yield) and Ru2Pt(CO)6[μ-η 2-C10H6C4Ph2]2, 4 (8% yield). Both compounds were characterized by a single crystal X-ray diffraction analysis. Both products were formed as a result of fragmentation of the Pt2Ru4 cluster of 1. Compound 3 contains two ruthenium atoms. They are bridged by a tricyclic C10H6C4Ph2 ligand formed by the coupling of the two α-carbon atoms of the alkyne groups. The β-carbon atoms of the alkynes are σ-bonded to one of the ruthenium atoms to form a metallacycle and this entire group is π-bonded to the second ruthenium atom. Compound 4 contains two ruthenium atoms with a platinum atom between them. This molecule contains two tricyclic C10H6C4Ph2 ligands similar to that in 3, and two metallacycles formed by coordination of the β-carbon atoms of both ligands to the platinum atom. One ligand is π-bonded to each of the ruthenium atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009052412595
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of excess PbO or MgO and purity of MgO on phase structure and dielectric properties of PMN-PT ceramics prepared by MSS (2000)
    Springer
    Journal of materials science 19 (2000), S. 1743-1746 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006726901927
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  • 3
    Electronic Resource
    Electronic Resource
    A structural model of Cr/(Ba,Pb)TiO3 positive temperature coefficient composite (2000)
    Springer
    Journal of materials science 11 (2000), S. 235-238 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The over-current protector is one of the main applications of the positive temperature coefficient (PTC) thermistor. Low room-temperature resistance and a PTC effect are required for the use of the over-current protection. As a result, lowering the room-temperature resistivity of PTC materials becomes very important. From a Japanese patent, the method of adding metal to BaTiO3-based PTC ceramics to form composites has shown good results. But in recent publications, few papers were related to this area. Furthermore, in the limited literature, the resistance–temperature curve of the material expressed a negative temperature coefficient (NTC) effect when metal was present. In the present work, chromium (Cr), was added to (Ba,Pb)TiO3 ceramics to form PTC composite with higher Curie temperature (T C = 180°C). Under a given composition and method, the prepared composite had low room-temperature resistivity (p = 1.33Ωcm) and PTC effect (Pmax/Pmax = 10). From the experimental results obtained, a structural model of the composite is proposed. The co-function of metal and ceramics, and sintering atmosphere factor on the PTC effect are discussed in this model. By employing this model, the resistance–temperature properties of the composites can be explained satisfactorily.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008901000485
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  • 4
    Electronic Resource
    Electronic Resource
    Fluorescence Enhancement and Photostability of Novel Pentamethine Cyanines in Nafion-Na+ Membranes (2000)
    Springer
    Journal of fluorescence 10 (2000), S. 21-26 
    Details
    ISSN: 1573-4994
    Keywords: Pentamethine cyanine ; Nafion membranes ; fluorescence enhancement ; photostability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Four novel pentamethine cyanines have been investigated for their photophysical behaviors and photochemical stability in Nafion-Na+ membranes. The incorporation processes of these dyes into Nafion membranes are diffusion-controlled and the apparent diffusion constants have been determined. Fluorescence quantum yields and fluorescence lifetimes of all tested dyes in Nafion membranes have been determined and significant fluorescence enhancements were observed with respect to their fluorescence in aqueous solution. Photolysis of these dyes suggested these dye molecules are stabilized significantly by Nafion membranes. Furthermore, the fluorescence enhancements and the photostabilization of these dyes are more significant in dry Nafion membranes than those in wet ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009479311842
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  • 5
    Electronic Resource
    Electronic Resource
    Very Negative Potential for Half-inactivation of, and Effects of Anions on, Voltage-dependent Sodium Currents in Acutely Isolated Rat Olfactory Receptor Neurons (2000)
    Springer
    The journal of membrane biology 175 (2000), S. 123-138 
    Details
    ISSN: 1432-1424
    Keywords: Key words: Olfactory receptor neuron — Sodium currents — Fluoride — Phosphate — Acetate — Patch clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. Previous measurements with CsF pipette solutions using whole-cell patch-clamp techniques in dissociated rat olfactory receptor neurons (ORNs) indicated that the sodium currents had very negative inactivation characteristics with the implication that the cell resting potential must also normally have a very negative value. This study supports the conclusions that such an effect was real and not dependent on either the nature of the pipette anions or the recording situation previously used. For all pipette solutions, sodium currents showed a threshold activation ≈−80 mV and half-maximal activation voltages ≈−55 with half-inactivation potential ≤−100 mV, without being significantly affected by the replacement of F− by other pipette anions (H2PO− 4 and acetate−) or the addition of nucleotides and glutathione (which did cause a very slight positive shift). F−, followed by H2PO− 4 and to a much lesser extent by acetate−, was the most favorable pipette anion for obtaining good seals and whole-cell sodium currents in these extremely small ORNs. These results implied that resting potentials, for viable responsive cells, should be more negative than about −90 mV, as supported by the observation that action potentials could only be evoked from holding potentials more negative than −90 mV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002320001061
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  • 6
    Electronic Resource
    Electronic Resource
    Ion Permeation and Selectivity of Wild-Type Recombinant Rat CNG (rOCNC1) Channels Expressed in HEK293 Cells (2000)
    Springer
    The journal of membrane biology 178 (2000), S. 137-150 
    Details
    ISSN: 1432-1424
    Keywords: Key words: Recombinant rat cyclic nucleotide-gated channel (rOCNC1) — Selectivity — Permeation — Cation — Patch clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. The permeation properties of adenosine 3′, 5′-cyclic monophosphate (cAMP)-activated recombinant rat olfactory cyclic nucleotide-gated channels (rOCNC1) in human embryonic kidney (HEK 293) cells were investigated using inside-out excised membrane patches. The relative permeability of these rOCNC1 channels to monovalent alkali cations and organic cations was determined from measurements of the changes in reversal potential upon replacing sodium in the bathing solution with different test cations. The permeability ratio of Cl− relative to Na+ (P Cl /P Na ) was about 0.14, confirming that these channels are mainly permeable to cations. The sequence of relative permeabilities of monovalent alkali metal ions in these channels was P Na ≥P K 〉 P Li 〉 P Cs ≥P Rb , which closely corresponds to a high-strength field sequence as previously determined for native rat olfactory receptor neurons (ORNs). The permeability sequence for organic cations relative to sodium was P NH3OH 〉 P NH4 〉 P Na 〉 P Tris 〉 P Choline 〉 P TEA , again in good agreement with previous permeability ratios obtained in native rat ORNs. Single-channel conductance sequences agreed surprisingly well with permeability sequences. These conductance measurements also indicated that, even in asymmetric bi-ionic cation solutions, the conductance was somewhat independent of current direction and dependent on the composition of both solutions. These results indicate that the permeability properties of rOCNC1 channels are similar to those of native rat CNG channels, and provide a suitable reference point for exploring the molecular basis of ion selectivity in recombinant rOCNC1 channels using site-directed mutagenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002320010021
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  • 7
    Electronic Resource
    Electronic Resource
    Resistance to wheat streak mosaic virus in transgenic wheat expressing the viral replicase (NIb) gene (2000)
    Springer
    Molecular breeding 6 (2000), S. 469-477 
    Details
    ISSN: 1572-9788
    Keywords: pathogen-derived resistance ; replicase-mediated resistance ; wheat transformation ; WSMV.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat (Triticum aestivum L. cv. Hi-Line) immature embryos were transformed with the replicase gene (NIb) of wheat streak mosaic virus (WSMV) by the biolistic method. Six independent transgenic plant lines were analyzed for transgene expression and for resistance to mechanical inoculation of WSMV at R3 or R4 generation. Four out of the six lines showed various degree of resistance to WSMV. These lines had initially milder symptoms than controls, and the new growth ranged from milder symptoms, a substantial delay in symptom development, or asymptomatic. Two lines displayed higher resistance with very mild virus symptoms after inoculation and the new growth of 72% and 32% plants from these lines were asymptomatic and had no detectable virus through the plant life cycle. Interestingly, five out of the six transgenic lines had no detectable transgene mRNA expression by RNA gel blot hybridization. The only line that had detectable transgene mRNA did not show delay in the symptom development but had overall milder symptom to the virus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026576124482
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  • 8
    Electronic Resource
    Electronic Resource
    Origins of Spiral Wave Meander and Breakup in a Two-Dimensional Cardiac Tissue Model (2000)
    Springer
    Annals of biomedical engineering 28 (2000), S. 755-771 
    Details
    ISSN: 1573-9686
    Keywords: Reentry ; Arrhythmias ; Restitution ; Stability ; Electrophysiology ; Simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract We studied the stability of spiral waves in homogeneous two-dimensional cardiac tissue using phase I of the Luo–Rudy ventricular action potential model. By changing the conductance and the relaxation time constants of the ion channels, various spiral wave phenotypes, including stable, quasiperiodically meandering, chaotically meandering, and breakup were observed. Stable and quasiperiodically meandering spiral waves occurred when the slope of action potential duration (APD) restitution was 〈1 over all diastolic intervals visited during reentry; chaotic meander and spiral wave breakup occurred when the slope of APD restitution exceeded 1. Curvature of the wave changes both conduction velocity and APD, and their restitution properties, thereby modulating local stability in a spiral wave, resulting in distinct spiral wave phenotypes. In the LR1 model, quasiperiodic meander is most sensitive to the Na+ current, whereas chaotic meander and breakup are more dependent on the Ca2+ and K+ currents. © 2000 Biomedical Engineering Society. PAC00: 8719Hh, 8717Nn, 8717Aa, 8716Uv
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.1289474
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  • 9
    Electronic Resource
    Electronic Resource
    An extended random primer amplified region (ERPAR) marker linked to a dominant male sterility gene in cabbage (Brassica oleracea var. capitata) (2000)
    Springer
    Euphytica 112 (2000), S. 267-273 
    Details
    ISSN: 1573-5060
    Keywords: cabbage (Brassica oleracea var. capitata) ; ERPAR ; RAPD ; male sterility gene ; molecular marker
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Similar to SCAR, an extended random primer amplified region (ERPAR) marker is a PCR amplified genomic DNA fragment at a single genetically defined locus. However, ERPAR uses specific primer pairs derived from RAPD primers by adding bases sequentially to their 3′-ends. As an example, an ERPAR marker was derived from a RAPD marker (OT11900) linked to a dominant male sterility gene in cabbage (Brassica oleracea var. capitata). After two cycles of base adding and primer pair screening, a primer pair (5′-TTCCCCGCGACT-3′and 5′-TTCCCCGCGAGA-3′) amplified a single intense band with the same size as OT11900. The identity of the new marker and OT11900 was verified by segregation analysis. The new marker amplified by this extended primer pair was named as EPT11900. The development of ERPAR exploits the importance of 3′-end bases of primers in PCR ERPAR shares advantages of SCAR, but eliminates the need for cloning and sequencing. It is a fast and universal way of converting RAPD markers into stable markers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003903627969
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  • 10
    Electronic Resource
    Electronic Resource
    Nonlocal Symmetries and Associated Conservation Laws for Wave Equations with Variable Speeds (2000)
    Springer
    International journal of theoretical physics 39 (2000), S. 2503-2512 
    Details
    ISSN: 1572-9575
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We show that one can generate a class of nontrivial conservation laws for second-orderpartial differential equations using some recent results dealing with theaction of any Lie—Bäklund symmetry generator of the equivalent first-ordersystem on the respective conservation law. These conserved vectors are nonlocal asthey are constructed from associated nonlocal symmetries of the partial differentialequation. We demonstrate the complete procedure on certain classes of waveequations with variable wave speeds. Some of these have been considered in theliterature using alternative methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026445222247
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