Double helix formation of poly(m-phenylene)s bearing achiral oligo(ethylene oxide) pendants and transformation into an excess of one-handed single helix through cholate binding in water

2009 ◽  
Vol 7 (12) ◽  
pp. 2509 ◽  
Author(s):  
Teng Ben ◽  
Yoshio Furusho ◽  
Hidetoshi Goto ◽  
Kazuhiro Miwa ◽  
Eiji Yashima
Keyword(s):  
Ethylene Oxide ◽  
Double Helix ◽  
Helix Formation ◽  
Single Helix

Mercury Electrodes in Nucleic Acid Electrochemistry: Sensitive Analytical Tools and Probes of DNA Structure. A Review

2004 ◽  
Vol 69 (4) ◽  
pp. 715-747 ◽  
Author(s):  
Miroslav Fojta
Keyword(s):  
Nucleic Acid ◽  
Nucleic Acids ◽  
Double Helix ◽  
Dna Structure ◽  
Electrochemical Analysis ◽  
Label Free ◽  
Helix Formation ◽  
Mercury Electrodes ◽  
Dna Strand ◽  
Dna Double Helix

This review is devoted to applications of mercury electrodes in the electrochemical analysis of nucleic acids and in studies of DNA structure and interactions. At the mercury electrodes, nucleic acids yield faradaic signals due to redox processes involving adenine, cytosine and guanine residues, and tensammetric signals due to adsorption/desorption of polynucleotide chains at the electrode surface. Some of these signals are highly sensitive to DNA structure, providing information about conformation changes of the DNA double helix, formation of DNA strand breaks as well as covalent or non-covalent DNA interactions with small molecules (including genotoxic agents, drugs, etc.). Measurements at mercury electrodes allow for determination of small quantities of unmodified or electrochemically labeled nucleic acids. DNA-modified mercury electrodes have been used as biodetectors for DNA damaging agents or as detection electrodes in DNA hybridization assays. Mercury film and solid amalgam electrodes possess similar features in the nucleic acid analysis to mercury drop electrodes. On the contrary, intrinsic (label-free) DNA electrochemical responses at other (non-mercury) solid electrodes cannot provide information about small changes of the DNA structure. A review with 188 references.

Vapor Phase Growth of Carbon Microcoils / Nanocoils

2005 ◽  
Vol 23 ◽  
pp. 387-0
Author(s):  
S. Yang ◽  
X. Chen ◽  
S. Motojima
Keyword(s):  
Heat Treatment ◽  
Catalytic Pyrolysis ◽  
Double Helix ◽  
Phase Growth ◽  
High Temperature Heat Treatment ◽  
Coil Diameter ◽  
Temperature Heat ◽  
Α Helix ◽  
Temperature Heat Treatment ◽  
Single Helix

The carbon microcoils and carbon nanocoils were prepared by the catalytic pyrolysis of acetylene under the Ni and/or Fe-containing catalysts, and the growth pattern, morphology and growth mechanism of the carbon coils were examined in detail. The inner coil diameter of carbon microcoils are of several µm and coil gap from zero to several µm. The inner coil diameter of carbon nanocoils are from zero to several ten nm and coil gap from zero to several nm. The carbon microcoils are generally of double helix coils such as DNA while carbon nanocoils were single helix coils such as α-helix proteins, with spring-like or twisted forms. A catalyst grain was usually observed on the tip of carbon coil. The carbon nanocoils are almost amorphous and can be graphitized by the high temperature heat-treatment.

Reversible Ligand‐Gated Ion Channel via Interconversion between Hollow Single Helix and Intertwined Double Helix

2020 ◽  
Vol 132 (32) ◽  
pp. 13704-13709
Author(s):  
Dongya Bai ◽  
Tengfei Yan ◽  
Shi Wang ◽  
Yanbo Wang ◽  
Jiya Fu ◽  
...  
Keyword(s):  
Ion Channel ◽  
Double Helix ◽  
Single Helix

scholarly journals Innenrücktitelbild: Enantiodifferentiating Photodimerization of a 2,6‐Disubstituted Anthracene Assisted by Supramolecular Double‐Helix Formation with Chiral Amines (Angew. Chem. 19/2020)

2020 ◽  
Vol 132 (19) ◽  
pp. 7695-7695
Author(s):  
Akio Urushima ◽  
Daisuke Taura ◽  
Makoto Tanaka ◽  
Naomichi Horimoto ◽  
Junki Tanabe ◽  
...  
Keyword(s):  
Double Helix ◽  
Chiral Amines ◽  
Helix Formation

scholarly journals Base-base mismatches. Thermodynamics of double helix formation for dCA3XA3G + dCT3YT3G (X, Y = A,C,G,D

1985 ◽  
Vol 13 (13) ◽  
pp. 4811-4824 ◽  
Author(s):  
Fareed Aboul-ela ◽  
David Koh ◽  
Ignacio Tinoco ◽  
Francis H. Martin
Keyword(s):  
Double Helix ◽  
Helix Formation

scholarly journals A weakly nonlinear mechanism for mode selection in swirling jets

2012 ◽  
Vol 699 ◽  
pp. 216-262 ◽  
Author(s):  
Philippe Meliga ◽  
François Gallaire ◽  
Jean-Marc Chomaz
Keyword(s):  
Normal Form ◽  
Numerical Simulations ◽  
Vortex Breakdown ◽  
Double Helix ◽  
Mode Selection ◽  
Direct Numerical Simulations ◽  
Swirling Jets ◽  
Graphic Mode ◽  
Stable Solutions ◽  
Single Helix

AbstractGlobal linear and nonlinear bifurcation analysis is used to revisit the spiral vortex breakdown of nominally axisymmetric swirling jets. For the parameters considered herein, stability analyses single out two unstable linear modes of azimuthal wavenumber $m= \ensuremath{-} 1$ and $m= \ensuremath{-} 2$, bifurcating from the axisymmetric breakdown solution. These modes are interpreted in terms of spiral perturbations wrapped around and behind the axisymmetric bubble, rotating in time in the same direction as the swirling flow but winding in space in the opposite direction. Issues are addressed regarding the role of these modes with respect to the existence, mode selection and internal structure of vortex breakdown, as assessed from the three-dimensional direct numerical simulations of Ruith et al. (J. Fluid Mech., vol. 486, 2003, pp. 331–378). The normal form describing the leading-order nonlinear interaction between modes is computed and analysed. It admits two stable solutions corresponding to pure single and double helices. At large swirl, the axisymmetric solution bifurcates to the double helix which remains the only stable solution. At low and moderate swirl, it bifurcates first to the single helix, and subsequently to the double helix through a series of subcritical bifurcations yielding hysteresis over a finite range of Reynolds numbers, the estimated bifurcation threshold being in good agreement with that observed in the direct numerical simulations. Evidence is provided that this selection is not to be ascribed to classical mean flow corrections induced by the existence of the unstable modes, but to a non-trivial competition between harmonics. Because the frequencies of the leading modes approach a strong $2$:$1$ resonance, an alternative normal form allowing interactions between the $m= \ensuremath{-} 2$ mode and the first harmonics of the $m= \ensuremath{-} 1$ mode is computed and analysed. It admits two stable solutions, the double helix already identified in the non-resonant case, and a single helix differing from that observed in the non-resonant case only by the presence of a slaved, phase-locked harmonic deformation. On behalf of the finite departure from the $2$:$1$ resonance, the amplitude of the slaved harmonic is however low, and the effect of the resonance on the bifurcation structure is merely limited to a reduction of the hysteresis range.

scholarly journals Figure-eight thermal hysteresis of aminomethylenehelicene oligomers with terminal C16 alkyl groups during hetero-double-helix formation

2020 ◽  
Vol 11 (12) ◽  
pp. 3290-3300 ◽  
Author(s):  
Tsukasa Sawato ◽  
Rina Iwamoto ◽  
Masahiko Yamaguchi
Keyword(s):  
Structural Changes ◽  
Thermal Hysteresis ◽  
Double Helix ◽  
Random Coils ◽  
Helix Formation ◽  
Double Helices ◽  
Alkyl Groups

1 : 1 mixtures of aminomethylenehelicene (P)-tetramer and (M)-pentamer with terminal C16 alkyl groups in fluorobenzene showed structural changes between hetero-double-helices B and C and random-coils 2A.

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