Viscoelastic blood flow through arterial stenosis—Effect of variable viscosity

Current theoretical investigation deals with mathematical model of unsteady non-Newtonian flow of blood through a stenosed artery. The flowing blood is considered as a viscoelastic fluid having shear-thinning rheology and characterized by generalised Oldroyd-B model. The arterial wall is considered to be rigid having cosine shaped stenosis in its lumen. The governing equations of motion accompanied by appropriate choice of the initial and boundary conditions are solved numerically by MAC (Marker and Cell) method and the results are checked for numerical stability with desired degree of accuracy. The quantitative analysis has been carried out finally which includes the respective profiles of the flow-field. The key factors like the wall shear stress and flow separation are also examined for further qualitative insight into the flow through arterial stenosis. The present results show quite consistency with several existing results in the literature which substantiate sufficiently to validate the applicability of the model under consideration.     

Building-up Remarkably Stable Magnesium Porphyrin Polymers Self-Assembled via Bidentate Axial Ligands: Synthesis, Structure, Surface Morphology, and Effect of Bridging Ligands

A series of supramolecular architectures of magnesium tetranitrooctaethylporphyrins mediated by several bidentate axial ligands have been synthesized in excellent yields and structurally characterized. Six conjugated axial ligand with increasing chain lengths have been utilized in the present investigations in which the Mg···Mg nonbonding distance between successive ions also increases from 0.73 to 2.70 nm in the series. To the best of our knowledge, this is the first report where stable metallo-porphyrin polymers with such long spacers have been synthesized in one pot so easily. Linear one-dimensional (1D) polymeric chains were observed in the X-ray structure of the six-coordinated complexes in which porphyrin units are aligned parallel to each other to have so-called "shish kebab" like architectures to maintain offset-stacked overlap. However, after an optimum Mg···Mg nonbonding distance, these 1D chain do not continue, rather they form five-coordinated porphyrin dimers with "wheel-and-axle" like architectures which are then self-aggregated by π-π interactions in a perpendicular manner to fill space created by large bridging ligands more effectively which consequently results in spherical structures. The structures of the molecules in solution and their surface patterns on highly ordered pyrolytic graphite (HOPG) have also been investigated.     

Unsteady response of non-Newtonian blood flow through a stenosed artery in magnetic field

Current theoretical investigation of atherosclerotic arteries deals with mathematical models that represent non-Newtonian flow of blood through a stenosed artery in the presence of a transverse magnetic field. Here, the rheology of the flowing blood is characterised by a generalised Power law model. The distensibility of an arterial wall has been accounted for based on local fluid mechanics. A radial coordinate transformation is initiated to map cosine geometry of the stenosis into a rectangular grid. An appropriate finite difference scheme has been adopted to solve the unsteady non-Newtonian momentum equations in cylindrical coordinate system. Exploiting suitably prescribed conditions based on the assumption of an axial symmetry under laminar flow condition rendered the problem effectively to two dimensions. An extensive quantitative analysis has been performed based on numerical computations in order to estimate the effects of Hartmann number (M$M$), Power law index (n$n$), generalised Reynolds number (R_eG)$\left(R{e}_G\right)$, severity of the stenosis (δ)$\left(\delta \right)$ on various parameters such as flow velocity, flux and wall shear stress by means of their graphical representations so as to validate the applicability of the proposed mathematical model. The present results agree with some of the existing findings in the literature.     

Development of 1‐Hydroxy‐2(1H)‐quinolone‐Based Photoacid Generators and Photoresponsive Polymer Surfaces

A new class of carboxylate and sulfonate esters of 1‐hydroxy‐2(1H)‐quinolone has been demonstrated as nonionic photoacid generators (PAGs). Irradiation of carboxylates and sulfonates of 1‐hydroxy‐2(1H)‐quinolone by UV light (λ≥310 nm) resulted in homolysis of weak N? O bond leading to efficient generation of carboxylic and sulfonic acids, respectively. The mechanism for the homolytic N? O bond cleavage was supported by time‐dependent DFT calculations. Photoresponsive 1‐(p‐styrenesulfonyloxy)‐2‐quinolone–methyl methacrylate (SSQL‐MMA) and 1‐(p‐styrenesulfonyloxy)‐2‐quinolone–lauryl acrylate (SSQL‐LA) copolymers were synthesized from PAG monomer 1‐(p‐styrenesulfonyloxy)‐2‐quinolone, and subsequently controlled surface wettability was demonstrated for the above‐mentioned photoresponsive polymers.     

Development of 1-Hydroxy-2(1H)-quinolone-Based Photoacid Generators and Photoresponsive Polymer Surfaces

A new class of carboxylate and sulfonate esters of 1-hydroxy-2(1H)-quinolone has been demonstrated as nonionic photoacid generators (PAGs). Irradiation of carboxylates and sulfonates of 1-hydroxy-2(1H)-quinolone by UV light (λ≥310?nm) resulted in homolysis of weak N?O bond leading to efficient generation of carboxylic and sulfonic acids, respectively. The mechanism for the homolytic N?O bond cleavage was supported by time-dependent DFT calculations. Photoresponsive 1-(p-styrenesulfonyloxy)-2-quinolone-methyl methacrylate (SSQL-MMA) and 1-(p-styrenesulfonyloxy)-2-quinolone-lauryl acrylate (SSQL-LA) copolymers were synthesized from PAG monomer 1-(p-styrenesulfonyloxy)-2-quinolone, and subsequently controlled surface wettability was demonstrated for the above-mentioned photoresponsive polymers.     

Exploring the potential of fluoro-flavonoid derivatives as anti-lung cancer agents: DFT,molecular docking,and molecular dynamics techniques

The present investigation utilized in silico methodologies to explore the diverse pharmacological activities, toxicity profiles, and chemical reactivity of a series of fluoro-flavonoid compounds ( 1 – 14 ), which are secondary metabolites of plants known for their broad range of biological effects. A comprehensive strategy is utilized, incorporating methods such as prediction of activity spectra for substances (PASS) prediction, absorption, distribution, metabolism, excretion, and toxicity (ADMET) assessments, and density functional theory (B3LYP) calculations using three basis sets: 6-31G(d,p), 6-311G(d,p), and 6-311++G(d,p). Furthermore, the study employed molecular docking technique to identify target proteins, including HER2 (7JXH), EGFR (4UV7), FPPS (1YQ7), HPGDS (1V40), DCK (1P60), and KEAP1 on Nrf2 (1X2J), for the investigated compounds, with cianidanol and genistein serving as reference drugs for the docking process. The investigated fluoro-flavonoid compounds exhibited significantly greater binding affinities (ranging from −8.3 to −10.6 kcal mol⁻¹) toward HER2, HPGDS, and KEAP1 compared to the reference drugs, cianidanol and genistein, which displayed binding affinities ranging from −8.4 to −9.4 kcal mol⁻¹. Furthermore, molecular dynamics simulations were conducted to assess the stability of the protein-ligand interaction, using the root-mean-square deviation (RMSD), root-mean-square fluctuation (RMSF), Radius of gyration (Rg) parameters and principle component analysis (PCA). Among the tested fluoro-flavonoid analogs, analog 11 showed a RMSD value of .15 nm with the HER2 protein target, indicating a stable interaction. Based on in silico results, it appears that the fluoro-flavonoid compound 11 has the potential to serve as a targeted anti-lung cancer drug. However, additional in vivo and in vitro studies are necessary to confirm this hypothesis.     

Chromatographic analysis,antimicrobial and insecticidal activities of the essential oil of Phlomis floccosa D. Don.

The present study was conducted to investigate for the first time the chemical composition and insecticidal and antimicrobial properties of Phlomis floccosa D. Don. essential oil isolated by hydro‐distillation of its aerial parts. Qualitative and quantitative analyses of the essential oil on the basis of gas chromatography and mass spectrometry (GC/FID and GC/MS) revealed the presence of 59 organic volatiles representing 86.9% of the total constituents. The major compounds were germacrene‐D (19.7%) followed by β‐caryophyllene (15.5%), caryophyllene oxide (8.3%), hexadecenoic acid (7.9%) and carvacrol (6.1%). The broth microdilution method was conducted to test the antimicrobial activity of the essential oil against five pathogens: Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica, Staphylococcus aureus, Bacillus subtilis and the yeast Candida albicans. The oil of P. floccosa D. Don. shows promising activity against the Gram‐positive bacteria S. aureus and B. subtilis and the yeast C. albicans (minimum inhibitory concentration = 625 μg.mL^?1). The effectiveness of the essential oil was assessed on both Tribolium confusum and Sitophilus zeamais pest insects and it was more pronounced against T. confusum, showing a moderate mortality of 47.5%.     

Heteroleptic transition metal complexes of Schiff‐base‐derived ligands exert their antifungal activity by disrupting membrane integrity

Development of new treatment strategies and chemotherapeutic agents is urgently needed to combat the growing multidrug resistant species of Candida. In this direction, a new series of Cu (II), Co (II), Ni (II) and Zn (II) heteroleptic complexes were synthesized, characterized and evaluated for antifungal activity. Based on spectral characterization and physical measurements, an octahedral geometry was assigned to [Co(L1)(L2)ClH₂O] ( C2 ), [Ni(L1)(L2)ClH₂O] ( C3 ), [Zn(L1)(L2)ClH₂O] ( C4 ) complexes, while a distorted octahedral geometry was assigned to [Cu(L1)(L2)ClH₂O] ( C1 ) complex. All the synthesized compounds were tested for antifungal activity against 11 Candida albicans isolates, including fluconazole (FLC)‐resistant isolates, by determining minimum inhibitory concentrations (MIC) and minimum fungicidal concentrations (MFC), following CLSI guidelines. The mechanism of their antifungal activity was assessed by studying their effect on the plasma membrane using flow cytometry and quantifying the ergosterol contents. All the test compounds showed varying levels of antifungal activity. Both the ligands showed moderate antifungal activity with a median MIC value of 100 μg/mL with no fungicidal activity. Compound C3 was the most potent compound with median MIC and MFC values of 0.10 and 1.60 μg/mL, respectively. Flow cytometry analysis revealed that these compounds at MFC values disrupt the cell membrane, resulting in propidium iodide entering the cells. These compounds also reduced a considerable amount of ergosterol content after treating the cells with MIC and sub‐MIC values. This study indicates that these compounds have high antifungal activity against C. albicans, and have the potential to be developed as novel antifungal drugs.     

Induction of supramolecular chirality in di-zinc(II) bisporphyrin via tweezer formation: synthesis, structure and rationalization of chirality

Two new supramolecular complexes consisting of an achiral bisporphyrin host and a chiral diamine guest are reported. One shows a remarkably high amplitude bisignate CD signal while the other one shows a very low value. X-ray structure and other spectroscopic investigations of the tweezer complexes clearly rationalize the origin of the optical activity that has so far remained an unresolved issue.     

Simulation du front d'écoulement dans les procédés de moulage des composites liquides

This work proposes a procedure of finite difference discretized in a system of curvilinear coordinates adapted to the shape of the saturated zone, to simulate a flow in the LCM (Liquid Composites Molding) process. Formulation and the numerical application of the procedure are described. We describe two configurations of injections. A good agreement is found between numerical, analytical and literature experimental results. To cite this article: M. Hattabi et al., C. R. Mecanique 333 (2005).