Implication of Cross-Diffusion on the Stability of Double Diffusive Convection in an Imposed Magnetic Field

The effects of cross-diffusion on linear and weak nonlinear stability of double diffusive convection in an electrically conducting horizontal fluid layer with an imposed vertical magnetic field are investigated. The criterion for the onset of stationary and oscillatory convection is obtained analytically by performing the linear instability analysis. Several noteworthy departures from those of doubly diffusive fluid systems are unveiled under certain parametric conditions. It is shown that (i) disconnected closed convex oscillatory neutral curve separated from the stationary neutral curve exists requiring three critical thermal Rayleigh numbers to completely specify the linear instability criteria instead of a usual single critical value, (ii) an electrically conducting fluid layer in the presence of magnetic field can be destabilized by stable solute concentration gradient, and (iii) a doubly diffusive conducting fluid layer can be destabilized in the presence of magnetic field. It is demonstrated that small variations in the off-diagonal elements enforce discrepancies in the instability criteria. A weak nonlinear stationary stability analysis has been performed using a perturbation method and a cubic Landau equation is derived and the stability of bifurcating equilibrium solution is discussed. It is found that subcritical bifurcation occurs depending on the choices of governing parameters

Temporal variations in glucose level, oxidative stress and antioxidant profile of Koi carps (Cyprinus carpio var koi) in response to hypoxic tolerance

Biochemical analyses were conducted temporally to understand the impact of prolonged hypoxic environment on gill and white muscle of juvenile Koi carps (Cyprinus carpio var koi). The 16-day study involved quantification of Glucose (GLU), oxidative stress (Lipid Peroxidation—LPO) and antioxidant profile (Catalase—CAT, Glutathione—GSH, Glutathione-S-Transferase—GST) every 96th hour to understand the physiological consequences of hypoxic environment compared to normoxia (Control). There was no mortality throughout the study period, however, fishes were physically exhausted and exhibited Aquatic Surface Respiration (ASR) after day 8. Reduction in glucose levels was observed for both the tissues from day 4 to 16. LPO values increased in gill from day 4 to 12 followed by decrease on day 16. Catalase values reduced in gill from day 4 to 12 with an abrupt spike on day 16. Among the glutathione antioxidants, negligible GST activity was observed for day 12 and 16 in gill and muscle, while day 4 and 8 revealed fluctuations in GSH for both the tissues. The study showed tissue-specific differential response to stress because of a variance in the evaluated biomarkers in gill and muscle. Understanding the extent of physiological response to progressive oxygen disruption is essential for best practices in pisciculture because its availability is a critical factor impacting fish health which is congruent to the results of this study

Effect of Donor and Acceptor on Optoelectronic Properties of Benzo[1,2-B:4,5-B′]dithiophene

A series of acceptor and donor groups anchored to benzo[1,2-b:4,5-b′]dithiophene (BDT) molecule have been systematically investigated at the density functional theory (DFT) and time-dependent density functional theory (TDDFT) level to reveal structure–property relationships, charge transfer, and fluorescence lifetimes. The DFT optimization shows that the hetero atom in the ring induces the polarity from central ring to both ends of the thiophene ring, participating in the conjugation. The donor and acceptor groups were anchored at the terminals of the BDT at two different positions to fine-tune the properties according to the requirement and study the push–pull effect. All the models studied in this work retain their aromaticity as estimated from NICS(0) and NICS(1) aromaticity index in ground and excited states. The results show that the hardness, softness, HOMO–LUMO gaps, ionization potentials (IP), and electron affinities (EA) of the BDTs are significantly affected by the electron-withdrawing and electron-donating groups. The 1H and 13C NMR chemical shift values have been computed to quantify the push–pull effect. Further, the charge transfer properties in these BDTs were explored based on reorganization energies and diagnostic descriptors derived from hole–electron theory that present different electron excitation behavior. The relationship between the computed variables such as highest occupied molecular orbital, lowest unoccupied molecular orbital, oscillator strength, dipole moment, absorption, and fluorescence energy correlates the system with one another and also to extend the possible applications of the system in optical devices. Structure–property relationship of various BDTs reveal that, upon optical excitation, the resonance effect plays an important role changing the bonding character between the substituent and BDT unit, enabling efficient electron delocalization. The examination of TDDFT results indicates that among the various models studied in this work, nitro-substituted model is better candidate for optoelectronic properties with relatively large absorption wavelength and long fluorescence lifetime

Cattaneo-Ltne Effects on the Stability of Brinkman Convection in an Anisotropic Porous Layer

The stability of Brinkman local thermal nonequilibrium anisotropic porous convection under the impact of Cattaneo law of heat conduction in solid is investigated. In the analysis, anisotropies in permeability and thermal (solid and fluid phases) conductivities are highlighted. Condition for stationary onset and oscillatory onset is obtained by carrying out linear instability analysis. A novel result is that the instability occurs through oscillatory mode against the stationary convection perceived in the absence of Cattaneo effect. The relative magnitudes of governing parameters on the initiation of oscillatory instability are delineated in detail. The thermal and mechanical anisotropies inflict stabilizing and destabilizing effects on the onset, respectively. The influence of mechanical anisotropy, thermal anisotropy of fluid, thermal relaxation time parameters and the Darcy number is to broaden the size of convection cells whereas thermal anisotropy of the solid and the Darcy-Prandtl number demonstrate a mixed behaviour. A first order amplitude equation is derived separately for steady and overstable modes by performing a weak nonlinear stability analysis using a modified multiscale method. Depending on the values of governing parameters, it is seen that the stationary mode bifurcates subcritically and supercritically, while the oscillatory mode always bifurcates supercritically

Genome-scale protein interaction network construction and topology analysis of functional hypothetical proteins in Helicobacter pylori divulges novel therapeutic targets

The emergence and spread of multi-drug resistance among Helicobacter pylori (H. pylori) strain raise more stakes for genetic research for discovering new drugs. The quantity of uncharacterized hypothetical proteins in the genome may provide an opportunity to explore their property and promulgation could act as a platform for designing the drugs, making them an intriguing genetic target. In this context, the present study aims to identify the key hypothetical proteins (HPs) and their biological regulatory processes in H. pylori. This investigation could provide a foundation to establish the molecular connectivity among the pathways using topological analysis of the protein interaction networks (PINs). The giant network derived from the extended network has 374 nodes connected via 925 edges. A total of 43 proteins with high betweenness centrality (BC), 54 proteins with a large degree, and 23 proteins with high BC and large degrees have been identified. HP 1479, HP 0056, HP 1481, HP 1021, HP 0043, HP 1019, gmd, flgA, HP 0472, HP 1486, HP 1478, and HP 1473 are categorized as hub nodes because they have a higher number of direct connections and are potentially more important in understanding HP's molecular interactions. The pathway enrichment analysis of the network clusters revealed significant involvement of HPs in pathways such as flagellar assembly, bacterial chemotaxis and lipopolysaccharide biosynthesis. This comprehensive computational study revealed HP's functional role and its druggability characteristics, which could be useful in the development of drugs to combat H. pylori infections

Growth response of in vitro regenerated drymaria cordata (L.) willd. ex roem. & schult. to inoculation with arbuscular mycorrhizal fungi

Drymaria cordata (L.) Willd. ex Roem. & Schult. commonly known as ‘West Indian Chick weed’ is a potential herb used in traditional medicine in the treatment of many ailments. The main active principles therapeutically are known as drymaritin and isovitexin. Arbuscular mycorrhizae (AM) are symbiotic associations between plants and soil fungi that play a vital role in plant growth and development as well as soil quality. In the present investigation, an attempt was made to determine the growth responses of in vitro regenerated Drymaria cordata to inoculation with arbuscular mycorrhizal fungi. Both normal and in vitro regenerated plants of Drymaria cordata were inoculated with Glomus mosseae and Glomus fasciculatum. All the inoculated plants showed significant morphological results over control after a period of 30, 60 and 90 days of inoculation in polyhouse pot experiment. The percent of colonization and the number of spores in the rhizosphere of the in vitro regenerated plants are significantly more than the normal plants. Inoculation of in vitro regenerated plants with Glomus fasciculatum showed maximum mycorrhizal inoculation effect. Mycorrhizal inoculation significantly increased the biomass, root and shoot length, plant height, leaf area, number of branches, number of nodes per branch and internodal length. Such increases were related to the intensity of mycorrhizal association in the root. These findings indicate that mycorrhizal inoculation can be a suitable and alternative method to improve the growth of Drymaria cordata

Neutron Diffraction Magnetic and Mossbauer Spectroscopic Studies of Pb0.8Bi0.2Fe0.728W0.264O3 and Pb0.7Bi0.3Fe0.762W0.231O3 Ceramics

We report on high-temperature crystallographic structure, magnetic and physical properties of chemically B-site disordered lead-bismuth iron tungstate, (PFW)1-x(BFO)x (which can be written as Pb0.8Bi0.2Fe0.728W0.264O3 (0.8PFW–0.2BFO) for x = 0.2 and Pb0.7Bi0.3Fe0.762W0.231O3 (0.7PFW–0.3BFO) for x = 0.3) or PBFW), solid solutions through neutron diffraction (ND), magnetization, electron paramagnetic resonance, and Mössbauer spectroscopic studies. From the high temperature magnetic susceptibility measurement, it is observed that increase antiferromagnetic to paramagnetic phase transition around TN = 435 K (Pb0.8Bi0.2Fe0.728W0.264O3) and 504 K (Pb0.7Bi0.3Fe0.762W0.231O3), compared to pure PFW. Room-temperature crystallographic study confirms the formation of pseudo cubic structure with Pm-3m space group, whereas the magnetic structure is commensurate G-type antiferromagnetic ordering. The obtained temperature dependent structural parameters from the ND, evidenced to existence of strong spin-lattice coupling around TN for both the compounds. The discontinuity in the Pb/Bi–O bond length around ferroelectric transition (TC) indicates the presence of magnetoelectric coupling. Interestingly, microscopic 1:1 B-site ordered nanoclusters of PBFW exhibits the ferrimagnetic clusters along with antiferromagnetic order and it observed through the opening of M vs H hysteresis curves in the lower field regime. The EPR and Mössbauer spectroscopic studies well support the magnetic property and also reveal the Fe+3 state, and the weak signal in EPR and broader linewidth in the Mössbauer spectra exhibit the B-site disorderliness

Horizontal pressure gradient and Soret effects on the onset of thermosolutal porous convection

The intricacies of a constant horizontal pressure gradient on the onset of Soret-driven thermosolutal porous convection have been investigated. The resulting generalized eigenvalue problem is solved numerically using the Galerkin method and also the condition for the onset is obtained in a closed-form using a single-term Galerkin method with trigonometric trial function. The results obtained from both methods are found to be in good agreement. The effect of increasing horizontal pressure gradient, Lewis number, Soret parameter, and the Vadasz number is to hasten, while the increase in the solute Darcy–Rayleigh number is to delay the onset of oscillatory convection. The presence of the horizontal pressure gradient is found to decrease the threshold value of solute Darcy–Rayleigh number beyond which the instability sets in as oscillatory. Moreover, the horizontal pressure gradient imparts a conflicting behavior on the critical wave number and critical frequency of oscillations. The numerical results attained under the limiting cases are shown to be in excellent agreement with the published ones