Instability mechanism for miscible two-fluid channel flow with wall slip

Modal analysis of the Reynolds-Orr energy equation for a miscible viscosity stratified slippery channel flow is deliberated. The main aim is to extend the earlier work of Ghosh et al. (Phys. Fluid, Vol. 26, 014107 (2014)) to discusses the instability mechanism, which has not been investigated so far. The generalized equation governing the average rate of change of disturbance kinetic energy is evaluated after solving the Orr-Sommerfeld boundary value problem. The analysis includes viscosity perturbation and slip boundary condition. Maximum growth rate curves for two-dimensional disturbances reconfirm the existence of new unstable modes at low Reynolds numbers. Stabilizing and destabilizing effects of wall velocity slip are found depending on parameter regime. The physical mechanism responsible for the dual role of the wall slip is brought to light by estimating the alteration of kinetic energy due to the production and dissipation of energy originating from various factors inside the perturbed flow. Slip boundary condition at the wall affects the base flow as well as perturbations. Our numerical calculations here show how the wall velocity slip gives impact on each energy terms. The results ensure that, the new unstable mode is occurred due to the overlap of velocity and viscosity disturbance vortices. Stability characteristics of this overlap instability are ruled by the energy sourcing from the Reynolds stress and the viscosity perturbation gradient effect.SCOPUS: ar.jDecretOANoAutActifinfo:eu-repo/semantics/publishe

Oblique Long Wave Scattering by an Array of Bottom-Standing Non-Smooth Breakwaters

Bragg scattering of surface gravity waves by an array of submerged bottom-standing non-smooth breakwaters is studied under the assumption of linearized long wave theory. The closed-form long-wave analytical solutions are derived and validated by comparing them with the results available in the literature. The role of various physical parameters such as breakwaters friction coefficient, depth, width and gap between the adjacent breakwaters are investigated by analyzing the reflection and transmission coefficients. Further, the time-domain simulation for the scattering of long gravity waves over multiple breakwaters is analysed for different values of parameters of breakwaters. The results reveal that the rough surface of the breakwater plays a vital role in reducing wave reflection and transmission. Moreover, it is observed that the transmitted wave dissipates completely for larger values of friction parameters. For certain critical angles, change in wave dissipation becomes maximum due to the variation of phase of the incident wave. Various findings can be considered as benchmark results for the design of the non-smooth structures to attenuate the waves based on the Bragg reflection

Anion-Selective Cholesterol Decorated Macrocyclic Transmembrane Ion Carriers

Anion transporters play a vital role in cellular processes and their dysregulation leads to a range of diseases such as cystic fibrosis, Bartter’s syndrome and epilepsy. Synthetic chloride transporters are known to induce apoptosis in cancer cell lines. Herein, we report triamide macrocycles that are easily synthesized and externally functionalized by pendant membrane-permeable groups. Among a variety of chains appended onto the macrocycle scaffold, cholesterol is found to be the best with an EC₅₀ value of 0.44 μM. The macrocycle is highly anion-selective and transports ions via an OH^–/X^– antiport mechanism. The macrocycle is an interesting scaffold for ion-transport as it is able to discriminate between various anions and shows a preference for SCN^– and Cl^–. Such anion-selective transporters are highly attractive model systems to study ion-transport mechanisms and could potentially be of high therapeutic value

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Effect of imposed shear on the dynamics of a contaminated two-layer film flow down a slippery incline

The linear instability of a surfactant-laden two-layer falling film over an inclined slippery wall is analyzed under an influence of external shear which is imposed on the top surface of the flow. The free surface of the flow as well as the interface among the fluids are contaminated by insoluble surfactants. Dynamics of both the layers are governed by the Navier--Stokes equations, and the surfactant transport equation regulates the motion of the insoluble surfactants at the interface and free surface. Instability mechanisms are compared by imposing the external shear along and opposite to the flow direction. A coupled Orr--Sommerfeld system of equations for the considered problem is derived using the perturbation technique and normal mode analysis. The eigenmodes corresponding to the Orr--Sommerfeld eigenvalue problem are obtained by employing the spectral collocation method. The numerical results imply that the stronger external shear destabilizes the interface mode instability. However, a stabilizing impact of the external shear on the surface mode is noticed if the shear is imposed in the flow direction, which is in contrast to the role of imposed external shear on the surface mode for a surfactant laden single layer falling film. Moreover, the impression of shear mode on the primary instability is analyzed in the high Reynolds number regime with sufficiently low inclination angle. Under such configuration, dominance of the shear mode over the surface mode is observed due to the weaker impact of the gravitation force on the surface instability. The shear mode can also be stabilized by applying the external shear in the counter direction of the streamwise flow. Conclusively, the extra imposed shear on the stratified two-layer falling film plays an active role to control the attitude of the instabilities

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Not AvailableRice sheath blight (ShB) disease, caused by the fungal pathogen Rhizoctonia solani AG1-IA, is one of the devastating diseases and causes severe yield losses all over the world. No completely resistant germplasm is known till now, and as a result, the progress in resistance breeding is unsatisfactory. Basic studies to identify candidate genes, QTLs, and to better understand the host–pathogen interaction are also scanty. In this study, we report the identification of a new ShB-tolerant rice germplasm, CR 1014. Further, we investigated the basis of tolerance by exploring the disease responsive differentially expressed transcriptome and comparing them with that of a susceptible variety, Swarna-Sub1. A total of 815 and 551 genes were found to be differentially regulated in CR 1014 and Swarna-Sub1, respectively, at two different time points. The result shows that the ability to upregulate genes for glycosyl hydrolase, secondary metabolite biosynthesis, cytoskeleton and membrane integrity, the glycolytic pathway, and maintaining photosynthesis make CR 1014 a superior performer in resisting the ShB pathogen. We discuss several putative candidate genes for ShB resistance. The present study, for the first time, revealed the basis of ShB tolerance in the germplasm CR1014 and should prove to be particularly valuable in understanding molecular response to ShB infection. The knowledge could be utilized to devise strategies to manage the disease better.Not Availabl

Scalable Pillar[5]arene-Integrated Poly(arylate-amide) Molecular Sieve Membranes to Separate Light Gases

Molecular sieve membranes and their analogues could potentially transform energy-intensive gas separation processes. However, many such membranes suffer from either limited process ability or physical stability including plasticization of semi-flexible microstructures. Here, we report on a new variation of all-polymer-based molecular sieve membranes that could tackle these specific challenges. These membranes were prepared by the interfacial polymerization of pillar[5]arene, m-phenylenediamine, and trimesoyl chloride to create characteristic poly(arylate-amide) heteropolymer microstructures. Pillar[S]arenes were crosslinked into the films with net weight fractions of up to similar to 47%, wherein the, 4.7 angstrom cavities of pillar[5]arenes were interconnected with similar to 2.8 angstrom apertures. These microstructures provided preferred permeation paths for smaller molecules (He and H-2) among the tested light gases (He, H-2, CO2, O-2, N-2, and CH4) and resulted in significant molecular sieving effects with representative pure gas selectivities of 32 (H-2/CO2), 150 (CO2/CH4), 4600 (H-2/CH4), 13 (O-2/N-2), and 4.7 (N-2/CH4) at 35 degrees C and 10 atm. These separation factors outperform most polymer-based gas separation membranes, while providing membrane features such as thin film barriers, cross-linked polymer backbones, and excellent processability resulting from interfacial polymerization that are critical for large-scale operations.11Nsciescopu