Search results for "periodic"
showing 10 items of 769 documents
Coupled fixed-point results for T-contractions on cone metric spaces with applications
2015
The notion of coupled fixed point was introduced in 2006 by Bhaskar and Lakshmikantham. On the other hand, Filipovićet al. [M. Filipovićet al., “Remarks on “Cone metric spaces and fixed-point theorems of T-Kannan and T-Chatterjea contractive mappings”,” Math. Comput. Modelling 54, 1467–1472 (2011)] proved several fixed and periodic point theorems for solid cones on cone metric spaces. In this paper we prove some coupled fixed-point theorems for certain T-contractions and study the existence of solutions of a system of nonlinear integral equations using the results of our work. The results of this paper extend and generalize well-known comparable results in the literature.
3,5-Bis(trifluoromethyl)phenyl 4-methylbenzenesulfonate
2017
Molecules of the title compound, C15H10F6O3S, are composed of 3,5-bis(trifluoromethyl)phenyl substituted with a toluene-4-sulfonate group. The dihedral angle between two aromatic moieties is 45.10 (5)°. In the crystal, molecules are connected by weak C—H...O and C—H...F contacts. One of the trifluoromethyl groups is disordered.
Crystal structure of (E)-4-[N-(7-methyl-2-phenyl-imidazo[1,2-a]pyridin-3-yl)carboximido-yl]phenol.
2015
The molecule of the title compound, C21H17N3O, is built up from fused five- and six-membered rings connected to a methyl group, a phenyl ring and an (iminomethyl)phenol group. The fused ring system is almost planar (r.m.s. deviation = 0.031 Å) and forms dihedral angles of 64.97 (7) and 18.52 (6)° with the phenyl ring and the (iminomethyl)phenol group, respectively. In the crystal, centrosymmetric molecules are linked by pairs of C—H...π interactions into dimeric units, which are further connected by O–H...N hydrogen bonds to form layers parallel to (101).
Acetylhydroxamic acid
2017
There is one independent molecule in the asymmetric unit of the title compound (alternatively namedN-hydroxyacetamide), C2H5NO2. It crystallizes in the noncentrosymmetric space groupP43. The structure is an anhydrous form of acetylhydroxamic acid with typical geometry that corresponds well with the hydrated structure described by Bracher & Small [Acta Cryst.(1970), B26, 1705–1709]. In the crystal, N—H...O and O—H...O hydrogen bonds connect the molecules into chains in thec-axis direction.
Three phenanthroline-metal complexes with topologically similar but geometrically different conformations.
2016
Two out of the three very similar complexes described present twofold symmetry but not the third one, probably by way of a strong intramolecular C—H⋯O hydrogen bond disrupting the symmetry, a fact which is analysed in detail.
Crystal structure of allylammonium hydrogen succinate at 100 K
2014
The asymmetric unit of the title compound, C2H8N+·C4H5O4−, consists of two allylammonium cations and two hydrogen succinate anions (Z′ = 2). One of the cations has a near-perfectsyn-periplanar (cis) conformation with an N—C—C—C torsion angle of 0.4 (3)°, while the other is characterized by agaucheconformation and a torsion angle of 102.5 (3)°. Regarding the anions, three out of four carboxilic groups are twisted with respect to the central C–CH2–CH2–C group [dihedral angles = 24.4 (2), 31.2 (2) and 40.4 (2)°], the remaining one being instead almost coplanar, with a dihedral angle of 4.0 (2)°. In the crystal, there are two very short, near linear O—H...O hydrogen bonds between anions, with t…
Tetrakis(dimethoxyboryl)methane
2016
The title compound, tetrakis(dimethoxyboryl)methane (systematic name: octamethyl methanetetrayltetraboronate), C9H24B4O8or C[B(OMe)2]4, is a useful synthetic intermediate. Crystals of this compound at 102 K conform to the orthorhombic space groupPbcn. The molecules, which reside on sites of crystallographic twofold symmetry, have idealized -4 point symmetry like most other CX4molecules in which eachXgroup bears two non-H substituents at the 1-position. The central C atom has a slightly distorted tetrahedral coordination geometry, with C—B bond lengths of 1.5876 (16) and 1.5905 (16) Å. One of the methoxy groups is disordered over two sets of sites; the major component has an occupancy factor…
Synthesis, crystal structure and Hirshfeld analysis of a crystalline compound comprising a 1/1 mixture of 1-[(1R,4S)- and 1-[(1S,4R)-1,7,7-trimethyl-…
2020
A racemic mixture of (R)- and (S)-camphor thiosemicarbazone, which crystallizes in the centrosymmetric space group C2/c, is reported.
Stieltjes Differential Inclusions with Periodic Boundary Conditions without Upper Semicontinuity
2021
We are studying first order differential inclusions with periodic boundary conditions where the Stieltjes derivative with respect to a left-continuous non-decreasing function replaces the classical derivative. The involved set-valued mapping is not assumed to have compact and convex values, nor to be upper semicontinuous concerning the second argument everywhere, as in other related works. A condition involving the contingent derivative relative to the non-decreasing function (recently introduced and applied to initial value problems by R.L. Pouso, I.M. Marquez Albes, and J. Rodriguez-Lopez) is imposed on the set where the upper semicontinuity and the assumption to have compact convex value…
Coauthorship networks and institutional collaboration patterns in reproductive biology.
2007
Objective Reproductive biology is a highly productive area. By analyzing papers published in the major journals in the period 2003–2005, the collaborative patterns were characterized. Design Original research papers published in 2004 in the journals included in the first quartile of the category "Reproductive Biology" of the Journal Citation Reports (2005) were selected. A bibliometric analysis was carried out with the information obtained, thus building up the networks of coauthorship and institutional collaboration. Result(s) A total of 4,702 papers were analyzed, 96.75% signed in collaboration by two or more authors, the authors per paper index being 5.24; 73.73% of the papers were colla…