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1.
We study the collapse process of a homogeneous perfect fluid (in FLRW background) with a barotropic equation of state in Brans–Dicke (BD) theory in the presence of phase space deformation effects. Such a deformation is introduced as a particular type of non-commutativity between phase space coordinates. For the commutative case, it has been shown in the literature (Scheel, 1995), that the dust collapse in BD theory leads to the formation of a spacetime singularity which is covered by an event horizon. In comparison to general relativity (GR), the authors concluded that the final state of black holes in BD theory is identical to the GR case but differs from GR during the dynamical evolution of the collapse process. However, the presence of non-commutative effects influences the dynamics of the collapse scenario and consequently a non-singular evolution is developed in the sense that a bounce emerges at a minimum radius, after which an expanding phase begins. Such a behavior is observed for positive values of the BD coupling parameter. For large positive values of the BD coupling parameter, when non-commutative effects are present, the dynamics of collapse process differs from the GR case. Finally, we show that for negative values of the BD coupling parameter, the singularity is replaced by an oscillatory bounce occurring at a finite time, with the frequency of oscillation and amplitude being damped at late times. 相似文献
2.
Mehdi Amirnasr Mahdieh Rasouli Kurt Mereiter 《Journal of the Iranian Chemical Society》2013,10(2):275-282
Two new cobalt(III) complexes of the hexadentate ligand [1,4-bis[o-(pyridine-2-carboxamidophenyl)]-1,4-dithiobutane] (H2bpctb) with N4S2 donor set atoms have been synthesized. A reaction of Co(CH3COO)2·4H2O with (H2bpctb) leads to the formation of [CoIII(bpctb)]PF6 (1) having a CoN2(pyridine)N′2(amide)S2(thioether) coordination by symmetric bpctb2? ligand. A similar reaction under slightly different conditions, however, gives [CoIII(L a )(L b )] (2), resulting from a C–S bond cleavage reaction triggered by an acetate ion as a base, having CoN2(pyridine)N′2(amide)S(thioether)S′(thiolate) coordination. These two Co(III) complexes have been characterized by elemental analyses and spectroscopic methods, and the crystal and molecular structures of [CoIII(bpctb)]PF6 (1) in the form of the solvate (1·MeOH·H2O) and of [CoIII(L a )(L b )] (2) have been determined by X-ray crystallography. The Co atoms of both complexes exhibit distorted octahedral geometry. The electrochemical investigation of [Co(bpctb)]PF6·MeOH·H2O (1·MeOH·H2O) and [CoIII(L a )(L b )] (2) by cyclic voltammetry reveals a reversible CoIII–CoII redox process at E 1/2 = ?0.32 V (ΔE p = 80 mV); for 1, and E 1/2 = ?0. 87 V (ΔE p = 70 mV) for 2. 相似文献
3.
Fatemeh Torabi S. Farhad Masoudi Faezeh Rahmani Fatemeh S. Rasouli 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(3):1167-1174
A study was conducted to investigate a photoneutron spectrum based on a 25 MeV electron linac for treatment of deep-seated brain tumors in the context of boron neutron capture therapy (BNCT). Based on a series of Mont Carlo N-Particle simulations, tungsten and uranium with optimized geometry were selected as the most appropriate converters for (e,γ) and (γ,n) reactions, respectively. The final optimized photoneutron source yield was 5.78 × 1013 n/s/mA, which is a high value for these kinds of sources. A beam shaping assembly (BSA) for the proposed neutron source containing optimal moderators, filter, reflector, and collimator was simulated. Results showed that using this BSA enables us to meet International atomic energy agency recommended figures of merit at the BSA beam port. Also, the calculated in-phantom figures of merit and dose evaluation results via a simulated head phantom confirmed that the designed neutron source and its related BSA configuration can potentially treat deep-seated brain tumors in BNCT framework. In the present study, some in-phantom figures of merit such as advantage depth, advantage depth dose rate, advantage ratio, and treatment time are 7.6 cm, 0.7 Gy/min, 4.2, and 17.8 min, respectively. 相似文献
4.
Naser Seyed-Matin Amir Hossein Jalili Masih Hosseini Jenab Seyed Majid Zekordi Ali Afzali Chapar Rasouli Akbar Zamaniyan 《Plasma Chemistry and Plasma Processing》2010,30(3):333-347
The carbon dioxide reforming of methane to synthesis gas under DC-pulsed plasma was investigated. The effects of specific
input energy and feed ratio on the product distribution and also feed conversion was studied. At the input energy of about
11 eV/molecule per methane and/or carbon dioxide the feed conversion of 38% for CH4 and 28% for CO2 and product selectivity of 74% has been attained for H2 and CO at feed flow rate of 90 ml/min. The energy consumption in this work displays potential to further study and optimization
of the process. The importance of the electron impact reactions in the process was discussed. The results show that by prudent
tuning of system variables, the process be able to run in the way of synthesis gas, instead of hydrocarbon production. 相似文献
5.
In this paper, by analysis of the relationship between the Nehari manifold and fibering maps, we discuss the existence, multiplicity and nonexistence of positive weak solution for the $(p_1,p_2,\ldots ,p_n)$ -Laplacian systems with sign-changing weight functions. 相似文献
6.
In this paper, the effects of ion-pair formation on the gain dynamics of multi cavity optical automatic gain control erbium doped fiber amplifier is modelled. The inhomogeneous Cabezas simple model is used to write the rate and propagation equations for the active medium. The solution of the governing equations shows that in high concentration of the erbium ions, depending on the pumping rate, the relaxation oscillations are converted to nT-Periodic or even to chaotic behavior. Although the high concentration erbium ion in the optical amplifiers decreases the conversion efficiency and increases the threshold pump power, amplitude of the transient effects is reduced in the multi feedback-loop WDM amplifiers relative to the low concentration erbium ions multi feedback-loop optical amplifiers and ion-pairs, which act as a saturable absorber to compensate the gain tilt caused by the OAGC laser spectral hole burning. The theoretical results are in complete agreement with the previous published experimental results. 相似文献
7.
8.
In this paper by considering the notion of hyperlattice, we introduce good and s-good hyperlattices, homomorphism of hyperlattices and s-reflexives. We give some examples of them and we study their structures. We show that there exists a hyperlattice L such that ${x \vee x = \{x\}}In this paper by considering the notion of hyperlattice, we introduce good and s-good hyperlattices, homomorphism of hyperlattices
and s-reflexives. We give some examples of them and we study their structures. We show that there exists a hyperlattice L such that x úx = {x}{x \vee x = \{x\}} for all x ? L{x \in L} and there exist x, y ? L{x, y \in L} which card(x úy) 1 1{card(x \vee y) \ne 1}. Also, we define a topology on the set of prime ideals of a distributive hyperlattice L and we will call it S(L){{{\mathcal S}(L)}}, then we show that S(L){{{\mathcal S}(L)}} is a T
0-space. At the end, we obtain that each complemented distributive hyperlattice is a T
1-space. 相似文献
9.
S. Rasouli 《代数通讯》2013,41(8):2720-2737
In this article, by considering the notion of a hyperlattice and a superlattice, we give some examples of them, and we study their structures and their quotient structure with a regular relation. We introduce the relation ν on a hyperlattice L, and we let ν* be the transitive closure of ν. We show that ν* is a fundamental relation on a hyperlattice. The quotient L/ν* is called the fundamental lattice. Notice that the most important relations in hyperstructure theory are the fundamental ones. Finally, we give some interesting results about the fundamental lattices. 相似文献
10.
Rahimeh Rasouli Ahmed Barhoum Mikhael Bechelany Alain Dufresne 《Macromolecular bioscience》2019,19(2)
Unique features of nanofibers provide enormous potential in the field of biomedical and healthcare applications. Many studies have proven the extreme potential of nanofibers in front of current challenges in the medical and healthcare field. This review highlights the nanofiber technologies, unique properties, fabrication techniques (i.e., physical, chemical, and biological methods), and emerging applications in biomedical and healthcare fields. It summarizes the recent researches on nanofibers for drug delivery systems and controlled drug release, tissue‐engineered scaffolds, dressings for wound healing, biosensors, biomedical devices, medical implants, skin care, as well as air, water, and blood purification systems. Attention is given to different types of fibers (e.g., mesoporous, hollow, core‐shell nanofibers) fabricated from various materials and their potential biomedical applications. 相似文献