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31.
Mustapha Ishak 《Foundations of Physics》2007,37(10):1470-1498
Associated with the cosmic acceleration are the old and new cosmological constant problems, recently put into the more general context of the dark energy problem. In broad terms, the old problem is related to an unexpected order of magnitude of this component while the new problem is related to this magnitude being of the same order of the matter energy density during the present epoch of cosmic evolution. Current plans to measure the equation of state or density parameters certainly constitute an important approach; however, as we discuss, this approach is faced with serious feasibility challenges and is limited in the type of conclusive answers it could provide. Therefore, is it really too early to seek actively for new tests and approaches to these problems? In view of the difficulty of this endeavor, we argue in this work that a good place to start is by questioning some of the assumptions underlying the formulation of these problems and finding new ways to put this questioning to the test. First, we calculate how much fine tuning the cosmic coincidence problem represents. Next, we discuss the potential of some cosmological probes such as weak gravitational lensing to identify novel tests to probe dark energy questions and assumptions and provide an example of consistency tests. Then, motivated by some theorems in General Relativity, we discuss if the full identification of the cosmological constant with vacuum energy is unquestionable. We discuss some implications of the simplest solution for the principles of General Relativity. Also, we point out the relevance of experiments at the interface of astrophysics and quantum field theory, such as the Casimir effect in gravitational and cosmological contexts. We conclude that challenging some of the assumptions underlying the cosmological constant problems and putting them to the test may prove useful and necessary to make progress on these questions. 相似文献
32.
33.
Bazzi Aicha Abbiche Khalid Izzaouihda Safia Acharjee Nivedita Zejli Hanane Marakchi Khadija Komiha Najia El Issami Souad Bazzi Lahcen Hilali Mustapha 《Structural chemistry》2021,32(6):2183-2198
Structural Chemistry - A combined experimental and theoretical study is presented to predict and analyze the inhibition efficiency and adsorption mechanism of 4-aminobenzoic acid molecule for... 相似文献
34.
Abdullahi Mustapha Krystoff Busch Marta Patykiewicz Alistair Apedaile John Reglinski Alan R. Kennedy Timothy J. Prior 《Polyhedron》2008
The reaction of the Schiff base species tris-((2-hydroxybenzylidene)aminoethyl)-amine (TrenSal) and tris-((2-hydroxy-5-bromobenzylidene)aminoethyl)amine (Tren5BrSal) with the acetates of nickel and zinc are reported. Two trimetallic complexes (M3L2) of Tren5BrSal with nickel and zinc have been crystallographically characterised. The attempted crystallisation of bis-(tris-((2-hydroxybenzylidene)aminoethyl)amine nickel) nickel from solutions containing TMEDA lead to the production of two novel complexes: namely a nickel adduct of the partially hydrolysed TrenSal ligand and an interesting nickel bromide–carbonate salt. [(TrenSal)2Ni3] is reacted with PbCl2 to form a novel tetrametallic complex, [{(TrenSal)Ni}Pb(NC5H5)Cl]2, where a Pb2Cl2 moiety replaces the nickel at the core of the complex. Extending the study to include the related hexadentate ligand, 1,1,1-tris-((2-hydroxybenzylidene)-aminomethyl)propane (TEtSal), we were able to isolate and characterise both [(TEtSal)2Ni3] and [{(TEtSal)Ni}2Pb]. 相似文献
35.
36.
Maleic anhydride was reacted with p-aminophenol and p-toluidine in the presence of di-phosphorus pentoxide (P?O?) as a catalyst to produce two compounds: N-(4-hydroxy-phenyl)maleimide (I) and N-(4-methylphenyl)maleimide (II). The new azo compounds I(a-c) and II(a-c) were prepared by the reaction of I and II with three different aromatic amines, namely aniline, p-aminophenol and p-toluidine. The structures of these compounds were confirmed by CHN, FT-IR, 1H-NMR, 13C-NMR, mass spectrum and UV/Vis spectroscopy. 相似文献
37.
Bernard Masereel Mustapha Dinguizli Caroline Bouzin Nicolas Moniotte Olivier Feron Bernard Gallez Thierry Vander Borght Carine Michiels Stéphane Lucas 《Journal of nanoparticle research》2011,13(4):1573-1580
Nanoscale materials are used in the biomedical field for magnetic resonance imaging, protein detection and drug/gene delivery.
Gold nanoparticles (AuNPs) are particularly investigated in cancer treatment and imaging. In this study, we described a simple
and reliable liquid method to coat AuNPs (diameter: 21 nm) layer-by-layer with alternative cationic polyallylamine and anionic
polystyrenesulfonate. The C-terminal amino acid of the antibody directed against anti-bovine serum albumin was activated by
EDC/NHS, and then condensed with the amino functions of the external polyallylamine layer. An ELISA test confirmed that the
antigen recognition of the bioconjugate antibody was conserved. This AuNP coating and the covalently coupling could be used
as a generic process for binding other specific antibodies, particularly those overexpressed in cancer cells and angiogenesis. 相似文献
38.
Mustapha Mokhtar-Kharroubi 《Acta Appl Math》2014,134(1):1-20
We show how some fundamental spectral properties of neutron transport semigroups in L p spaces (1<p<+∞), such as stability of essential spectra or critical spectra and related results, can be inferred from the study of two measure convolution operators on \(\mathbb{R}^{n}\) . 相似文献
39.
Mustapha Hellou Thi Diep Phuong Bach 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2011,11(3):135-147
The purpose of this study is to calculate Stokes flow structures in relation to flow rate distribution in a junction of four
orthogonal channels. Particular attention was paid to the existence of recirculation flow inside the channels for low Reynolds
numbers. The presence of this recirculation flow may be observed, but only when the flow rate is relatively low in at least
one of the branches. 相似文献
40.
Mustapha?Azreg-A?nou 《General Relativity and Gravitation》2010,42(6):1427-1456
We investigate the generic properties of static, spherically symmetric, asymptotically flat solutions to the field equations
describing gravity minimally coupled to a nonlinear self-gravitating real scalar field. Five corollaries and a theorem on
selection criteria for two- and one-parametric solutions are proven and conditions for obtaining particle-like solutions,
black holes or naked singularities are derived. A series of exact solutions in closed forms including different black holes,
naked singularities and particle-like solutions, all of which obey the weak energy condition at spatial infinity, are provided.
Two further corollaries elaborate on the behavior of solutions at spatial infinity, critical mass, mass density, pressure
and energy conditions. 相似文献