scholarly journals Tied links in various topological settings

2021 ◽  
pp. 2150046
Author(s):  
Ioannis Diamantis
Keyword(s):  
Molecular Biology ◽  
Solid Torus ◽  
Braid Groups ◽  
Lens Spaces ◽  
New Class ◽  
Knot Complements ◽  
Genus Formula ◽  
Potential Use ◽  
Text Component

Tied links in [Formula: see text] were introduced by Aicardi and Juyumaya as standard links in [Formula: see text] equipped with some non-embedded arcs, called ties, joining some components of the link. Tied links in the Solid Torus were then naturally generalized by Flores. In this paper, we study this new class of links in other topological settings. More precisely, we study tied links in the lens spaces [Formula: see text], in handlebodies of genus [Formula: see text], and in the complement of the [Formula: see text]-component unlink. We introduce the tied braid monoids [Formula: see text] by combining the algebraic mixed braid groups defined by Lambropoulou and the tied braid monoid, and we formulate and prove analogues of the Alexander and the Markov theorems for tied links in the 3-manifolds mentioned above. We also present an [Formula: see text]-move braid equivalence for tied braids and we discuss further research related to tied links in knot complements and c.c.o. 3-manifolds. The theory of tied links has potential use in some aspects of molecular biology.

Topology of ambient manifolds of non-singular Morse – Smale flows with three periodic orbits

2021 ◽  
Vol 29 (6) ◽  
pp. 863-868
Author(s):  
Danila Shubin ◽  
◽  
Keyword(s):  
Periodic Orbits ◽  
Three Dimensional ◽  
Solid Torus ◽  
Lens Space ◽  
Tubular Neighborhood ◽  
Lens Spaces ◽  
Ambient Manifold ◽  
Orientable Manifold ◽  
Smale Flows ◽  
Published Result

The purpose of this study is to establish the topological properties of three-dimensional manifolds which admit Morse – Smale flows without fixed points (non-singular or NMS-flows) and give examples of such manifolds that are not lens spaces. Despite the fact that it is known that any such manifold is a union of circular handles, their topology can be investigated additionally and refined in the case of a small number of orbits. For example, in the case of a flow with two non-twisted (having a tubular neighborhood homeomorphic to a solid torus) orbits, the topology of such manifolds is established exactly: any ambient manifold of an NMS-flow with two orbits is a lens space. Previously, it was believed that all prime manifolds admitting NMS-flows with at most three non-twisted orbits have the same topology. Methods. In this paper, we consider suspensions over Morse – Smale diffeomorphisms with three periodic orbits. These suspensions, in turn, are NMS-flows with three periodic trajectories. Universal coverings of the ambient manifolds of these flows and lens spaces are considered. Results. In this paper, we present a countable set of pairwise distinct simple 3-manifolds admitting NMS-flows with exactly three non-twisted orbits. Conclusion. From the results of this paper it follows that there is a countable set of pairwise distinct three-dimensional manifolds other than lens spaces, which refutes the previously published result that any simple orientable manifold admitting an NMS-flow with at most three orbits is lens space.

scholarly journals The aphid BCR4 structure and activity uncover a new defensin peptide superfamily

2021 ◽  
Author(s):  
Karine Loth ◽  
Nicolas Parisot ◽  
Francoise Paquet ◽  
Catherine Sivignon ◽  
Isabelle Rahioui ◽  
...  
Keyword(s):  
Acyrthosiphon Pisum ◽  
3D Structure ◽  
Pea Aphid ◽  
Symbiotic Bacteria ◽  
Structural Class ◽  
New Class ◽  
Agricultural Plants ◽  
Nymphal Growth ◽  
Structure And Activity ◽  
Potential Use

Aphids (Hemiptera: Aphidoidea) are among the most injuring insects for agricultural plants and their management is a great challenge in agronomical research. A new class of proteins, called Bacteriocyte-specific Cysteine-Rich (BCR), provides an alternative to chemical insecticides for pest control. BCRs have been initially identified in the pea aphid Acyrthosiphon pisum. They are small disulfide bond-rich proteins expressed exclusively in aphid bacteriocytes, the insect derived cells that host intracellular symbiotic bacteria. Here, we show that one out of the A. pisum BCRs, BCR4, displays an outstanding insecticidal activity against the pea aphid, impairing insect survival and nymphal growth, providing evidence for its potential use as a new biopesticides. Our comparative genomics and phylogenetic analysis indicate that BCRs seem restricted to the aphid lineage. The 3D structure of the BCR4 reveals that this peptide belongs to a yet unknown structural class of peptides and defines a new superfamily of defensins.

scholarly journals Antimicrobial Activity of the Iron-Sulfur Nitroso Compound Roussin's Black Salt [Fe4S3(NO)7] on the Hyperthermophilic Archaeon Pyrococcus furiosus

2009 ◽  
Vol 75 (7) ◽  
pp. 1820-1825 ◽  
Author(s):  
Scott D. Hamilton-Brehm ◽  
Gerrit J. Schut ◽  
Michael W. W. Adams
Keyword(s):  
Nitric Oxide ◽  
Antimicrobial Agent ◽  
Pyrococcus Furiosus ◽  
Cell Lysis ◽  
Nitroso Compound ◽  
Hyperthermophilic Archaeon ◽  
New Class ◽  
Iron Sulfur ◽  
Sulfur Reductase ◽  
Potential Use

ABSTRACT The iron-sulfur nitroso compound [Fe4S3(NO)7]− is a broad-spectrum antimicrobial agent that has been used for more than 100 years to combat pathogenic anaerobes. Known as Roussin's black salt (RBS), it contains seven moles of nitric oxide, the release of which was always assumed to mediate its cytotoxicity. Using the hyperthermophilic archaeon Pyrococcus furiosus, it is demonstrated through growth studies, membrane analyses, and scanning electron microscopy that nitric oxide does not play a role in RBS toxicity; rather, the mechanism involves membrane disruption leading to cell lysis. Moreover, insoluble elemental sulfur (S0), which is reduced by P. furiosus to hydrogen sulfide, prevents cell lysis by RBS. It is proposed that S0 also directly interacts with the membranes of P. furiosus during its transfer into the cell, ultimately for reduction by a cytosolic NADPH sulfur reductase. RBS is proposed to be a new class of inorganic antimicrobial agent that also has potential use as an inert cell-lysing agent.

REBa2ZrO5.5 (RE = La, Ce, Eu, and Yb): Synthesis, characterization, and their potential use as substrates for YBa2Cu3O7–δ superconductors

1997 ◽  
Vol 12 (11) ◽  
pp. 2976-2980 ◽  
Author(s):  
R. Jose ◽  
Asha M. John ◽  
J. Kurian ◽  
P. K. Sajith ◽  
J. Koshy
Keyword(s):  
Single Phase ◽  
Detrimental Effect ◽  
Solid State Reaction Method ◽  
Dielectric Constants ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resistivity Measurements ◽  
New Class ◽  
Zero Resistance ◽  
Potential Use

A new class of complex perovskites REBa2ZrO5.5 (where RE = La, Ce, Eu, and Yb) have been synthesized and sintered as single phase materials by the solid state reaction method. The structure of these materials was studied by x-ray diffraction, and all of them were found to be isostructural, having a cubic perovskite structure. X-ray diffraction and resistivity measurements have shown that there is no detectable chemical reaction between YBa2Cu3O7–delta; and REBa2ZrO5.5 even under severe heat treatment at 950 °C, and that the addition of REBa2ZrO5.5 up to 20 vol.% in YBa2Cu3O7–δ shows no detrimental effect on the superconducting properties of YBa2Cu3O7-δ. Dielectric constants and loss factors are in the range suitable for their use as substrates for microwave applications. Thick films of YBa2Cu3O7–δ fabricated on polycrystalline REBa2ZrO5.5 substrates gave a zero resistance transition temperature Tc(0) ∼ 92 K, indicating the suitability of these materials as substrates for YBa2Cu3O7–δ.

scholarly journals Section problems for configuration spaces of surfaces

2019 ◽  
pp. 1-29
Author(s):  
Lei Chen
Keyword(s):  
Finite Type ◽  
Braid Groups ◽  
Configuration Spaces ◽  
Easy Proof ◽  
Genus Formula

In this paper, we give a close-to-sharp answer to the basic questions: When is there a continuous way to add a point to a configuration of [Formula: see text] ordered points on a surface [Formula: see text] of finite type so that all the points are still distinct? When this is possible, what are all the ways to do it? More precisely, let PConf[Formula: see text] be the space of ordered [Formula: see text]-tuple of distinct points in [Formula: see text]. Let [Formula: see text] be the map given by [Formula: see text]. We classify all continuous sections of [Formula: see text] up to homotopy by proving the following: (1) If [Formula: see text] and [Formula: see text], any section of [Formula: see text] is either “adding a point at infinity” or “adding a point near [Formula: see text]”. (We define these two terms in Sec. 2.1; whether we can define “adding a point near [Formula: see text]” or “adding a point at infinity” depends in a delicate way on properties of [Formula: see text].) (2) If [Formula: see text] a [Formula: see text]-sphere and [Formula: see text], any section of [Formula: see text] is “adding a point near [Formula: see text]”; if [Formula: see text] and [Formula: see text], the bundle [Formula: see text] does not have a section. (We define this term in Sec. 3.2). (3) If [Formula: see text] a surface of genus [Formula: see text] and for [Formula: see text], we give an easy proof of [D. L. Gonçalves and J. Guaschi, On the structure of surface pure braid groups, J. Pure Appl. Algebra 182 (2003) 33–64, Theorem 2] that the bundle [Formula: see text] does not have a section.

scholarly journals An important step for the computation of the HOMFLYPT skein module of the lens spaces L(p,1) via braids

2019 ◽  
Vol 28 (11) ◽  
pp. 1940007 ◽  
Author(s):  
Ioannis Diamantis ◽  
Sofia Lambropoulou
Keyword(s):  
Infinite System ◽  
Solid Torus ◽  
Lens Spaces ◽  
System Of Equations ◽  
Skein Module ◽  
Knots And Links

We prove that, in order to derive the HOMFLYPT skein module of the lens spaces [Formula: see text] from the HOMFLYPT skein module of the solid torus, [Formula: see text], it suffices to solve an infinite system of equations obtained by imposing on the Lambropoulou invariant [Formula: see text] for knots and links in the solid torus, braid band moves that are performed only on the first moving strand of elements in a set [Formula: see text], augmenting the basis [Formula: see text] of [Formula: see text].

scholarly journals Exploring endoperoxides as a new entry for the synthesis of branched azasugars

2017 ◽  
Vol 13 ◽  
pp. 644-647 ◽  
Author(s):  
Svenja Domeyer ◽  
Mark Bjerregaard ◽  
Henrik Johansson ◽  
Daniel Sejer Pedersen
Keyword(s):  
Singlet Oxygen ◽  
Organic Synthesis ◽  
Building Blocks ◽  
New Class ◽  
Potential Use ◽  
New Entry

A new class of nitrogen-containing endoperoxides were synthesised by a photochemical [4 + 2]-cycloaddition between a diene and singlet oxygen. The endoperoxides were dihydroxylated and protected to provide a series of endoperoxide building blocks for organic synthesis, with potential use as precursors for the synthesis of branched azasugars. Preliminary exploration of the chemistry of these building blocks provided access to a variety of derivatives including tetrahydrofurans, epoxides and protected amino-tetraols.

Involutions of hyperbolic spatial graph exteriors whose fixed point sets are closed surfaces

2018 ◽  
Vol 27 (01) ◽  
pp. 1850004
Author(s):  
Toru Ikeda
Keyword(s):  
Fixed Point ◽  
Closed Surface ◽  
Heegaard Splittings ◽  
Fixed Point Set ◽  
Spatial Graph ◽  
Closed Surfaces ◽  
Point Set ◽  
Genus Formula ◽  
Graph Link ◽  
Text Component

A [Formula: see text]-component non-splittable spatial graph [Formula: see text] in [Formula: see text] possibly admits a smooth involution on its exterior whose fixed point set is a closed surface [Formula: see text] of genus [Formula: see text]. It is known that [Formula: see text] holds if [Formula: see text] is a graph link in [Formula: see text]. In this paper, we consider [Formula: see text] to be a hyperbolic spatial graph in a closed orientable 3-manifold [Formula: see text]. We first study the case where [Formula: see text] is the 3-sphere, and provide a method for constructing [Formula: see text] and [Formula: see text] with [Formula: see text], where [Formula: see text] is the Euler characteristic of [Formula: see text] for [Formula: see text]. Next, we study the case where [Formula: see text] is a closed orientable 3-manifold in relation to Heegaard splittings and Dehn surgeries.

ChemInform Abstract: METAL CARBONYL FRAGMENTS AS A NEW CLASS OF MARKERS IN MOLECULAR BIOLOGY

1985 ◽  
Vol 16 (47) ◽  
Author(s):  
G. JAOUEN ◽  
A. VESSIERES ◽  
S. TOP ◽  
A. A. ISMAIL ◽  
I. S. BUTLER
Keyword(s):  
Molecular Biology ◽  
Metal Carbonyl ◽  
New Class

New Hybrid Inorganic/Organic Block Copolymers as Templates for the Formation of Mesostructured Materials

2000 ◽  
Vol 628 ◽  
Author(s):  
Guido Kickelbick ◽  
Josef Bauer ◽  
Nicola Hüsing
Keyword(s):  
Block Copolymers ◽  
Ethylene Oxide ◽  
Inorganic Materials ◽  
Amphiphilic Block Copolymers ◽  
New Class ◽  
Mesostructured Silica ◽  
Mesostructured Materials ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Potential Use

ABSTRACTAmphiphilic block copolymers were prepared with poly(dimethylsiloxane) (PDMS) as the hydrophobic unit. The hydrophilic block was composed of either a poly (ethylene oxide) or a functionalized polysiloxane unit. The polymer based on polysiloxane blocks only, represents one of the first examples of a new class of surfactants with a purely inorganic Si-O backbone. Beside their potential use as templates for the synthesis of mesostructured inorganic materials, these new polymers offer the possibility of being transformed into porous mesostructured silica-based material by controlled pyrolysis.

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