排序方式: 共有32条查询结果,搜索用时 15 毫秒
1.
2.
Gaussian-type soliton solutions of the nonlinear Schrödinger (NLS) equation with fourth order dispersion, and power law nonlinearity in the novel parity-time (${ \mathcal P }{ \mathcal T }$)-symmetric quartic Gaussian potential are derived analytically and numerically. The exact analytical expressions of the solutions are obtained in the first two-dimensional (1D and 2D) power law NLS equations. By means of the linear stability analysis, the effect of power law nonlinearity on the stability of Gauss type solitons in different nonlinear media is carried out. Numerical investigations do confirm the stability of our soliton solutions in both focusing and defocusing cases, specially around the propagation parameters. 相似文献
3.
Peter T. Ndifon Moise O. Agwara Awawou G. Paboudam Divine M. Yufanyi Jean Ngoune Agustín Galindo Eleuterio Álvarez Aminou Mohamadou 《Transition Metal Chemistry》2009,34(7):745-750
A novel one-dimensional zigzag coordination polymer, dinitrodiaqua-bis(hexamethylenetetramine)cobalt(II) was synthesised and
characterised, and the structure was determined by single-crystal X-ray diffraction. The compound has a chain structure with
each cobalt atom covalently bonded to two nitrate ions, two water molecules and two HMTA molecules, giving a slightly distorted
octahedral geometry about the cobalt atom. Each HMTA ligand uses two of its N atoms to bond to two cobalt atoms giving an
approximately bent Co–HMTA–Co configuration. Each chain is hydrogen bonded through OH···N and OH···O interactions with neighbouring
chains leading to an overall polymer structure. Thermal studies show significant mass loss corresponding to the loss of the
coordinated water molecules and the decomposition of both the nitrate ions and the HMTA. 相似文献
4.
Spatial structures as a result of a modulational instability are obtained in the integrable discrete nonlinear Schrödinger equation (Ablowitz-Ladik equation). Discrete slow space variables are used in a general setting and the related finite differences are constructed. Analyzing the ensuing equation, we derive the modulational instability criterion from the discrete multiple scales approach. Numerical simulations in agreement with analytical studies lead to the disintegrations of the initial modulated waves into a train of pulses. 相似文献
5.
Etémé Armand Sylvin Tabi Conrad Bertand Beyala Ateba Jean Félix Ekobena Fouda Henry Paul Mohamadou Alidou Crépin Kofané Timoléon 《Nonlinear dynamics》2021,105(1):785-795
Nonlinear Dynamics - The fluctuation of ions concentration across the cell membrane of neuron can generate a time varying electromagnetic field. Thus, memristors are used to realize the coupling... 相似文献
6.
Tiofack Camus Gaston Latchio Tchepemen Nathan Nkouessi Mohamadou Alidou Kofané Timoléon Crépin 《Nonlinear dynamics》2019,98(1):317-326
Nonlinear Dynamics - We report on the existence and stability of Gaussian-type soliton in the nonlinear Schrödinger (NLS) equation with interplay of cubic–quintic nonlinearity,... 相似文献
7.
Importance of Outer‐Sphere and Aggregation Phenomena in the Relaxation Properties of Phosphonated Gadolinium Complexes with Potential Applications as MRI Contrast Agents 下载免费PDF全文
Dr. Mourad Elhabiri Dr. Sabah Abada Mohamadou Sy Dr. Aline Nonat Dr. Philippe Choquet Dr. David Esteban‐Gómez Dr. Claudio Cassino Dr. Carlos Platas‐Iglesias Prof. Mauro Botta Dr. Loïc J. Charbonnière 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6535-6546
A series composed of a tetra‐, a tris‐ and a bisphosphonated ligand based on a pyridine scaffold ( L4 , L3 and L2 , respectively) was studied within the frame of lanthanide (Ln) coordination. The stability constants of the complexes formed with lanthanide cations (Ln=La, Nd, Eu, Gd, Tb, Er and Lu) were determined by potentiometry in aqueous solutions (25.0 °C, 0.1 M NaClO4), showing that the tetraphosphonated complexes are among the most stable LnIII complexes reported in the literature. The complexation of L4 was further studied by different titration experiments using mass spectrometry and various spectroscopic techniques including UV/Vis absorption, and steady state and time‐resolved luminescence (Ln=Eu and Tb). Titration experiments confirmed the formation of highly stable [Ln L4 ] complexes. 31P NMR experiments of the Lu L4 complex revealed an intramolecular interconversion process which was studied at different temperatures and was rationalized by DFT modelling. The relaxivity properties of the GdIII complexes were studied by recording their 1H NMRD profiles at various temperatures, by temperature dependent 17O NMR experiments (Gd L4 ) and by pH dependent relaxivity measurements at 0.47 T (Gd L3 and Gd L2 ). In addition to the high relaxivity values observed for all complexes, the results showed an important second‐sphere contribution to relaxivity and pH dependent variations associated with the formation of aggregates for Gd L2 and Gd L3 . Finally, intravenous injection of Gd L4 to a mouse was followed by dynamic MRI imaging at 1.5 T, which showed that the complex can be immediately found in the blood stream and rapidly eliminated through the liver and in large part through the kidneys. 相似文献
8.
Gerard?A.?van?Albada Aminou?Mohamadou Anna?Maria?Manotti?Lanfredi Ilpo?Mutikainen Urho?Turpeinen Franco?Ugozzoli Jan?ReedijkEmail author 《Journal of chemical crystallography》2005,35(7):541-546
The synthesis, characterization and X-ray structures of two compounds with the general formula trans-M(biz)2(NCS)2 (in which biz = 2,2′-biimidazoline and M = Mn(II) for compound 1 and Ni(II) for compound 2) are reported. Both compounds crystallize in the triclinic space group P-1 with a = 8.393(5), b = 8.946(5), c = 7.659(5) Å, α = 104.440(5), β = 106.880(5), γ = 66.180(5)∘, V = 497.7(5) Å3, Z = 1 for compound 1 and a = 8.155(2), b = 8.8190(10), c = 7.480(2) Å, α = 102.259(15), β = 106.135(13), γ = 67.706(14)∘, V = 474.7(2) Å3, Z = 1 for compound 2.Both metal ions show octahedral coordination with the four nitrogen atoms of two biz ligands in the equatorial plane and the two nitrogen atoms of two isothiocyanate anions in the axial positions. The M–N≡C angles are 166.5(2) and 167.7(2) for compounds 1 and 2, respectively. These values are in the usually obtained range for trans-isothiocyanate coordinated compounds. The sulfur atom of each isothiocyanate anion acts as acceptor for the hydrogen bond with the NH group of the biz ligands. In the IR spectrum the vibrations of the thiocyanate anion are observed at 2090 and 776 cm−1 for compound 1 and at 2108 and 778 cm−1 for compound 2, and these values are typical for linear-bond isothiocyanate complexes of transition metals. 相似文献
9.
Nassera Tounsi Laurent Dupont Aminou Mohamadou Emmanuel Guillon Michel Aplincourt Guillaume Rogez 《Polyhedron》2008,27(18):3674-3682
Three new copper(II), nickel(II) and cobalt (II) dinuclear complexes with a bis-amide ligand derived from tartaric acid have been prepared and characterized. For this purpose, the ligand (R,R)-(+)-di-N,N′-methylpyridino-tartramide (dmpt) was synthesized via the classical aminolysis of (R,R)-(+)-dimethyltartrate with pyridylmethylamine. The molecular structures of the complexes Na[Cu2(dmptH−3)(CO3)] · 8H2O (1) and [Ni2(dmptH−2)2] · 9.75H2O (2) were elucidated by X-ray diffraction, and the complex [Co2(dmptH−3)(μ-OH)] · NaClO4 · 5H2O (3) by XAS. The crystal structure of (1) shows that the two metallic centres are in a square planar environment. Each copper(II) is bound to pyridyl and deprotonated amidic nitrogen atoms and to the oxygen atoms of hydroxyl and carbonato groups. In complex (2), both nickel atoms are in a distorted octahedral environment with an identical set of donors atoms, N4O2, coming from four nitrogen atoms of two pyridylmethylamido moieties and two oxygen donor atoms of alcohol groups. XAS analysis of complex (3) allows us to propose a CoN2O4 chromophore, with two nitrogen atoms coming from pyridyl and amidic groups and two bridged oxygen atoms from a deprotonated alcohol group and an hydroxyl group; the hexacoordination is achieved by two water molecules. The spectroscopic, electrochemical and magnetic properties of these complexes were investigated. 相似文献
10.
Matteo Perini Mohamadou Bawe Nfor Federica Camin Silvia Pianezze Edi Piasentier 《Molecules (Basel, Switzerland)》2021,26(8)
The purpose of this study was to address the lack of knowledge regarding the stable isotopic composition of beef from zebu cattle reared in tropical Africa. Sixty beef carcasses belonging to the most common zebu breeds (Goudali, white Fulani, and red Mbororo) were selected and classified according to their subcutaneous fat color (white, cream or yellow). The stable isotope ratios of five bioelements—H, O, C, N, and S—in muscle fractions and the fatty acids composition were analyzed. Zebu meat from Cameroon shows peculiar δ13C values, related to the almost exclusive intake of grazed tropical grasses with photosynthetic cycle C4. It also shows δ2H and δ18O values higher than those reported in other areas of the world and correlated with the isotopic composition of animal drinking water. The white subcutaneous fat (“white type”) zebu showed higher δ2H and lower δ13C than the “yellow type”, that is correlated with a higher content of polyunsaturated fatty acid (PUFA) and a lower amount of saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA). Multielement analysis seems to provide promising results for tracing the regional origin of Cameroon beef and some aspects of the livestock system, such as the nutritional status of the animals. 相似文献