86 research outputs found
On the effective action of the vacuum photon splitting in Lorentz violating QED through Krein space
The finding of an explicit effective action describing amplitude of photon
triple splitting is investigated through Krein space quantization and quantum
metric fluctuation. Using the derivative expansion method, the one-loop
radiative corrections from Lorentz- and CPT- violating extended Krein QED shows
that it is not possible to find a nonzero effective action
Euler-Heisenberg lagrangian through Krein regularization
The Euler-Heisenberg effective action at the one-loop for a constant
electromagnetic field is derived in Krein space quantization with Ford's idea
of uctuated light-cone. In this work we present a perturbative, but convergent
solution of the effective action. Without using any renormalization procedure,
the result coincides with the famous renormalized Euler-Heisenberg action.Comment: arXiv admin note: text overlap with arXiv:1109.269
QED effective action in Krein space quantization
The one-loop effective action of QED is calculated by the Schwinger method in
Krein space quantization. We show that the effective action is naturally fnite
and regularized. It also coincides with the renormalized solution which was
derived by Schwinger.Comment: 15 pages, Accepted for publication in Phys.Lett.
Regulation of Apoptosis, Invasion and Angiogenesis of Tumor Cells by Caffeic Acid Phenethyl Ester
Dual Doping of MoP with M(Mn,Fe) and S to Achieve High Hydrogen Evolution Reaction Activity in Both Acidic and Alkaline Media
Rational design of costâeffective, high performance and stable hydrogen evolution reaction (HER) electrocatalysts in both acidic and alkaline media holds the key to the future hydrogenâbased economy. Herein, we introduce an effective approach of simultaneous nonâmetal (S) and metal (Fe or Mn) doping of MoP to achieve excellent HER performance at different pH. The catalysts show remarkable overpotentials at â10â
mAâcmâ2 of only 65 and 68â
mV in 0.5â
M H2SO4, and 50 and 51â
mV in 1.0â
M KOH, respectively, as well as much higher turnover frequencies compared to undoped MoP. Furthermore, the catalysts exhibit outstanding longâterm stability at a fixed current of â10â
mAâcmâ2 for 40â
h. The effects of both dopants, such as electronic structure modification and enhancement of the intrinsic activity, increase of the electrochemically active surface area, and formation of coordinatively unsaturated edge sites, act cooperatively to accelerate the HER at both pH media. Additionally, the presence of oxophilic Mn and Fe at the surface results in Mn or Fe oxide/hydroxide species that promote the dissociation of water molecules in alkaline electrolyte. This work introduces a facile and effective design principle that could pave the way towards engineering highly active HER catalysts for a wide pH range.Metal (Mn or Fe) and nonâmetal (S) dual doped MoP catalysts were synthesiszed by reductive pyrolysis of the corresponding Mn,Moâ and Fe,Moâphosphonates precursors, in the presence of elemental S. The derived catalysts showed remarkable hydrogen evolution reaction (HER) activity in acidic and alkaline media. The dual doping process endowed MoP with proper hydrogen binding energy thus enhancing the HER in acidic media. In addition, Mn and Fe acted as surface oxides species in alkaline medium, which facilitated the water dissociation step.
imageYousef Jameel Scholarship FundPeer Reviewe
Krein Regularization of \lambda\phi^4
We calculate the four-point function in \lambda\phi^4 theory by using Krein
regularization and compare our result, which is finite, with the usual result
in \lambda\phi^4 theory. The effective coupling constant (\lambda_\mu) is also
calculated in this method
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