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  • 1
    Electronic Resource
    Electronic Resource
    The Biological Effect of Iron Oxide and Its Hydrate Nanoparticles (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 121-123 (Mar. 2007), p. 735-738 
    Details
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: Iron oxide and its hydrate nanoparticles were synthesized by hydrothermal method andconfirmed by infrared and SEM (Scanning Electron Microscope) et al. The dimensions of thenanoparticles are about 50-120 nm. The crystalline form of iron oxide nanoparticles is likeglobosity while its hydrate rod. Amino acids intermingling with the synthesized nanoparticles werecrystallized to investigate the space effect of the nanoparticles. The crystalline forms of crystal aredifferent to that of pure amino acid. The positions and width of the nanoparticles’ peaks in theinfrared spectrum are changed too. Microscope observation and infrared spectrum results indicatedthe nanoparticles had changed the internal structure of amino acids crystal. To considerate thetoxicity of the synthesized nanoparticles, MTT (3-(4,5-dimethylthiazol 2-yl)-2,5diphenyltetrazolium bromide) assay was used to determine their cytotoxicity. The OD value(Optical Density) was used to calculated RGR% (Relative Generation Rate) of cells, whichdetermined the grade of cytotoxicity. The RGR of nanoparticles of iron oxide and its hydrate areabout 1 to 2, which indicate they have just low toxicity
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/23/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.121-123.735.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    Food chain chaos due to junction-fold point (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Chaos 11 (2001), S. 514-525 
    Details
    ISSN: 1089-7682
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Consideration is given to a basic food chain model satisfying the trophic time diversification hypothesis which translates the model into a singularly perturbed system of three time scales. It is demonstrated that in some realistic system parameter region, the model has a unimodal or logistic-like Poincaré return map when the singular parameter for the fastest variable is at the limiting value 0. It is also demonstrated that the unimodal map goes through a sequence of period-doubling bifurcations to chaos. The mechanism for the creation of the unimodal criticality is due to the existence of a junction-fold point [B. Deng, J. Math. Biol. 38, 21–78 (1999)]. The fact that junction-fold points are structurally stable and the limiting structures persist gives us a rigorous but dynamical explanation as to why basic food chain dynamics can be chaotic. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1396340
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  • 3
    Electronic Resource
    Electronic Resource
    A proposed role of oxalic acid in wood decay systems of wood-rotting basidiomycetes (1994)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 13 (1994), S. 0 
    Details
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: The possible roles of oxalic acid, veratryl alcohol, and manganese were investigated in relation to lignin biodegradation by white-rot basidiomycetes. Oxalate inhibited both lignin peroxidase (LiP) and manganese-peroxidase (MnP). and was decarboxylated by the mediation of veratryl alcohol and Mn. Oxalate was shown to regulate the mineralization of lignin in the in vivo system of Phanerochaete chrysosporium. In the brown-rot wood decay process, oxalic acid may serve as an acid catalyst as well as an electron donor for the Fenton reaction, to breakdown cellulose and hemicellulose. Oxaloacetase and glyoxylate oxidase may play a key role in production of oxalic acid by white-rot and brown-rot basidiomycetes such as Phanerochaete chrysosporium, Coriolus versicolor and Tyromyces palustris. A possible role of oxalate metabolism is discussed in relation to the physiology of wood-rotting fungi.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6976.1994.tb00049.x
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  • 4
    Electronic Resource
    Electronic Resource
    Glucose-induced period-doubling cascade in the electrical activity of pancreatic β-cells (1999)
    Springer
    Journal of mathematical biology 38 (1999), S. 21-78 
    Details
    ISSN: 1432-1416
    Keywords: Key words: Bursting-spiking oscillations ; Continuous spiking oscillations ; Kneading sequence ; Period-doubling cascade ; Turning point ; Junction point ; Junction-fold point ; Slow manifold ; Stable and unstable foliations ; Poincaré map ; Asymptotic expansion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract  In the presence of stimulatory concentrations of glucose, the membrane potential of pancreatic β-cells may experience a transition from periods of rapid spike-like oscillations alternating with a pseudo-steady state to spike-only oscillations. Insulin secretion from β-cells closely correlates the periods of spike-like oscillations. The purpose of this paper is to study the mathematical structure which underlines this transitional stage in a pancreatic β-cell model. It is demonstrated that the transition can be chaotic but becomes more and more regular with increase in glucose. In particular, the system undergoes a reversed period-doubling cascade leading to the spike-only oscillations as the glucose concentration crosses a threshold. The transition interval in glucose concentration is estimated to be extremely small in terms of the rate of change for the calcium dynamics in the β-cells. The methods are based on the theory of unimodal maps and the geometric and asymptotic theories of singular perturbations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002850050141
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  • 5
    Electronic Resource
    Electronic Resource
    Conjugation for polynomial mappings (1995)
    Springer
    Zeitschrift für angewandte Mathematik und Physik 46 (1995), S. 872-882 
    Details
    ISSN: 1420-9039
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We consider Keller's functions, namely polynomial functionsf:C n →C n with detf(x)=1 at allx εC n. Keller conjectured that they are all bijective and have polynomial inverses. The problem is still open. Without loss of generality assumef(0)=0 andf'(0)=I. We study the existence of certain mappingsh λ, λ 〉 1, defined by power series in a ball with center at the origin, such thath′λ(0)=I andh λ(λf(x))=λh λ(x). So eachh λ conjugates λf to its linear part λI in a ball where it is injective. We conjecture that for Keller's functionsf of the homogeneous formf(x)=x +g(x),g(sx)=s dg(x),g′(x)n=0,xεC n,sεC the conjugationh λ for λf is anentire function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00917874
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  • 6
    Electronic Resource
    Electronic Resource
    Homoclinic bifurcation at resonant eigenvalues (1990)
    Springer
    Journal of dynamics and differential equations 2 (1990), S. 177-244 
    Details
    ISSN: 1572-9222
    Keywords: homoclinic orbit ; period doubling ; pathfollowing ; global bifurcation ; resonance ; 34C15 ; 34C35 ; 58F14
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We consider a bifurcation of homoclinic orbits, which is an analogue of period doubling in the limit of infinite period. This bifurcation can occur in generic two parameter vector fields when a homoclinic orbit is attached to a stationary point with resonant eigenvalues. The resonance condition requires the eigenvalues with positive/negative real part closest to zero to be real, simple, and equidistant to zero. Under an additional global twist condition, an exponentially flat bifurcation of double homoclinic orbits from the primary homoclinic branch is established rigorously. Moreover, associated period doublings of periodic orbits with almost infinite period are detected. If the global twist condition is violated, a resonant side switching occurs. This corresponds to an exponentially flat bifurcation of periodic saddle-node orbits from the homoclinic branch.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01057418
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  • 7
    Electronic Resource
    Electronic Resource
    Homoclinic twisting bifurcations and cusp horseshoe maps (1993)
    Springer
    Journal of dynamics and differential equations 5 (1993), S. 417-467 
    Details
    ISSN: 1572-9222
    Keywords: Strong inclination property ; neutrally twisted homoclinic orbits ; cusp horseshoe maps ; quotient symbolic systems ; singular perturbations ; 00A71 ; 34A34 ; 34C28 ; 34D30 ; 58F12 ; 58F13 ; 58F14 ; 58F40
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Chaotic dynamics arises when the unstable manifold of a hyperbolic equilibrium point changes its twist type along a homoclinic orbit as some generic parameter is varied. Such bifurcation points occur naturally in singularly perturbed systems. Some quotient symbolic systems induced from the Bernoulli symbolic system on two symbols are proved to be characteristic for this new mechanism of chaos generation. Combination of geometrical and analytical methods is proved to be more fruitful.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01053531
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  • 8
    Electronic Resource
    Electronic Resource
    A Practical Synthesis of 3-Methoxyflavones (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2169-2175 
    Details
    ISSN: 0947-3440
    Keywords: Baker-Venkataraman rearrangement ; 3-Methoxyflavones ; Phase-transfer catalysis ; Catalytic transfer hydrogenation ; Transesterifications ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some 3-methoxyflavones were known to possess antipicornavirus properties. In order to study the structure-activity relationship, attempts to prepare 3-methoxyflavone by literature methods were unsuccessful. We have modified the Baker-Venkataraman rearrangement, using a solid base and a phase-transfer catalyst. After searching optimal reaction conditions and a study of the intermediate formed in a model reaction, good yields were obtained for the 3-methoxyflavones 7, 21-32. Further some of the corresponding 7-O-n-butyl derivatives 4, 33-37 could be isolated as side products.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719971020
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  • 9
    Electronic Resource
    Electronic Resource
    A Practical Synthesis of 3-Methoxyflavones (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1243-1243 
    Details
    ISSN: 1434-193X
    Keywords: Correction ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Correction
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Synthesis of 7-Vinylflavone and 7-Aminoflavone by Palladium-Catalyzed Coupling Reactions (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 2683-2688 
    Details
    ISSN: 1434-193X
    Keywords: Flavone ; Palladium ; Cross coupling ; Triflate ; Aminations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Palladium-catalyzed cross-coupling reactions of flavone triflates 2a-c, 4a with tetravinyltin give the corresponding vinylflavones 5a-d, whereas reactions with benzophenone imine, followed by cleavage, afford the corresponding aminoflavone.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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