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41.
A positive cell vertex Godunov scheme for a Beeler–Reuter based model of cardiac electrical activity
Mostafa Bendahmane Fatima Mroue Mazen Saad 《Numerical Methods for Partial Differential Equations》2021,37(1):262-301
The monodomain model is a widely used model in electrocardiology to simulate the propagation of electrical potential in the myocardium. In this paper, we investigate a positive nonlinear control volume finite element scheme, based on Godunov's flux approximation of the diffusion term, for the monodomain model coupled to a physiological ionic model (the Beeler–Reuter model) and using an anisotropic diffusion tensor. In this scheme, degrees of freedom are assigned to vertices of a primal triangular mesh, as in conforming finite element methods. The diffusion term which involves an anisotropic tensor is discretized on a dual mesh using the diffusion fluxes provided by the conforming finite element reconstruction on the primal mesh and the other terms are discretized by means of an upwind finite volume method on the dual mesh. The scheme ensures the validity of the discrete maximum principle without any restriction on the transmissibility coefficients. By using a compactness argument, we obtain the convergence of the discrete solution and as a consequence, we get the existence of a weak solution of the original model. Finally, we illustrate by numerical simulations that the proposed scheme successfully removes nonphysical oscillations in the propagation of the wavefront and maintains conduction velocity close to physiological values. 相似文献
42.
Neel A. Mansukhani Erica B. Peters Miranda M. So Mazen S. Albaghdadi Zheng Wang Mark R. Karver Tristan D. Clemons Jeffrey P. Laux Nick D. Tsihlis Samuel I. Stupp Melina R. Kibbe 《Macromolecular bioscience》2019,19(6)
The rising prevalence of cardiovascular disease worldwide necessitates novel therapeutic approaches to manage atherosclerosis. Intravenously administered nanostructures are a promising noninvasive approach to deliver therapeutics that reduce plaque burden. The drug liver X receptor agonist GW3965 (LXR) can reduce atherosclerosis by promoting cholesterol efflux from plaque but causes liver toxicity when administered systemically at effective doses, thus preventing its clinical use. The ability of peptide amphiphile nanofibers containing apolipoprotein A1–derived targeting peptide 4F to serve as nanocarriers for LXR delivery (ApoA1‐LXR PA) in vivo is investigated here. These nanostructures are found to successfully target atherosclerotic lesions in a mouse model within 24 h of injection. After 8 weeks of intravenous administration, the nanostructures significantly reduce plaque burden in both male and female mice to a similar extent as LXR alone in comparison to saline‐treated controls. Furthermore, they do not cause increased liver toxicity in comparison to LXR treatments, which may be related to more controlled release by the nanostructure. These findings demonstrate the potential of supramolecular nanostructures as safe, effective drug nanocarriers to manage atherosclerosis. 相似文献
43.
Nadine Allendörfer Mazen Es-Sayed Martin Nieger Stefan Bräse 《Tetrahedron letters》2012,53(4):388-391
Organofluorine compounds are of high interest in modern drug discovery and material sciences. We herein report a new synthetic access to o-amino-2,2,2-trifluoroacetophenones starting from commercially available o-amino benzoic acids, which can easily be converted into the corresponding benzoxazinones. In a second step the trifluoromethylated ketone is formed via addition of Ruppert’s reagent following acidic work up. 相似文献
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Physics of the Solid State - Al-doped single wall carbon nanotube with Stone Wales defect was theoretically analyzed, two different orientations of chiral (8, 4) carbon nanotubes was doped among... 相似文献
47.
Mazen M. Abu-Khader 《Heat and Mass Transfer》2006,43(2):123-134
Tube inserts are used as heat transfer enhancement tool for both retrofit and new design of shell and tube heat exchangers. This paper discusses and reviews the characteristics and performance of twisted tapes. The theory and application are also addressed. Industrial case study was selected to illustrate the behaviour effect that the twisted tapes impose at various laminar, transition and turbulent flow regions. This effect was demonstrated by changing the inside tube diameter and twist ratio through evaluating selected exchanger design parameters such as: local heat transfer coefficient, friction factor and pressure drop. Testing the exponent powers for Re and Pr at both laminar and turbulent regions were carried out. General design considerations are outlined for the use of twisted tapes in shell and tube heat exchangers. 相似文献
48.
Journal of Computer-Aided Molecular Design - Zinc finger proteins (ZFP) play important roles in cellular processes. The DNA binding region of ZFP consists of 3 zinc finger DNA binding domains... 相似文献
49.
Mazen K. Nazal Mohammed A. Albayyari Fawwaz I. Khalili Ehsan Asoudani 《Journal of Radioanalytical and Nuclear Chemistry》2017,312(1):133-139
Importance of removal of radioactive elements from wastewater was the motivation behind this work. Synergistic solvent extraction of U(VI) and Th(IV) ions from perchlorate solution using didodecylphosphoric acid (HDDPA) incorporated with tri-n-butyl phosphate (TBP) or tri-n-octylphosphine oxide (TOPO) as a synergists have been studied for the first time. The effects of HDDPA concentration, synergist’s concentration, pH values and temperature on the extraction process have been studied. The thermodynamic parameters of the extraction process for these ions were calculated. It was found that the synergistic contribution of TOPO is higher than TBP in the extraction of Th(IV) and U(VI). 相似文献
50.
Barrero AF Herrador MM del Moral JF Arteaga P Akssira M El Hanbali F Arteaga JF Diéguez HR Sánchez EM 《The Journal of organic chemistry》2007,72(6):2251-2254
Titanocene monochloride catalyzes the homocoupling of benzylic halides and benzylic gem-dibromides to give the corresponding bibenzyl and stilbenyl systems. Exposure of benzylic bromides to Ti(III) in the presence of aldehydes gave rise to the Barbier-type products. Examples of the utility of the herein described processes are included. 相似文献