Vivekananda Mahavidyalaya is a college in Bardhaman, Purba Bardhaman district, West Bengal, India. It offers undergraduate courses in arts, commerce and sciences and postgraduate in chemistry. It is affiliated with University of Burdwan. It is a general degree college with postgraduate studies in chemistry.
Cu0.5Ni0.3Zn0.2Fe2O4 nanoparticles were synthesized via a sonochemical method and annealed at 600 degrees C to achieve a pure crystalline spinel phase. Rietveld refinement of the X-ray diffraction (XRD) pattern confirmed the phase purity, crystallite size and cationic distribution. FESEM and HRTEM images revealed that the nanocrystals are highly agglomerated due to strong magnetic interactions among the nanoparticles. EDAX was employed to confirm the elemental composition of the synthesized Cu0.5Ni0.3Zn0.2Fe2O4 nanoferrite. HRTEM analysis also ruled out the presence of any impurity phases. Fourier-transform infrared spectroscopy (FTIR) revealed characteristic metal-oxygen stretching vibrations at the tetrahedral lattice sites, while UV-vis spectroscopy showed a direct optical band gap of 2.23 eV. Magnetic measurements demonstrated near-saturation in the M-H loops in the low-field region (similar to 2000 Oe), indicating strong ferromagnetic behavior due to the presence of divalent Ni2+ ions in the spinel lattice. Photocatalytic studies using rhodamine-B dye under visible light irradiation showed that the degradation efficiency of CuFe2O4 (55%) increased to 78% with combined Zn and Ni doping. Kinetic analysis showed that a pseudo-second-order model was followed with a correlation coefficient of R2 = 0.995. The catalyst also exhibited good recyclability, retaining photocatalytic activity over three consecutive cycles. Cu0.5Ni0.3Zn0.2Fe2O4 nanoparticles served as an efficient heterogeneous catalyst for three-component Huisgen 1,3-dipolar CuAAC "click" reactions in aqueous media. The catalyst's stability, reusability, and ease of magnetic separation highlight its green chemistry potential. These multifunctional nanoparticles show great promise as visible-light-active photocatalysts and sustainable catalysts for organic transformations, contributing to key Sustainable Development Goals (SDGs).
Cypermethrin, a synthetic pyrethroid, has been found to contaminate water bodies adjacent to agricultural lands and is reported to be moderately toxic to the organisms living therein. This study examined the effects of cypermethrin on respiratory biomarkers in Oreochromis niloticus at four sub-lethal concentrations, including a control (0.0, 0.3, 0.6, and 1.0 µg/L) over 96 h. The actual concentrations were analytically confirmed through GC-ECD, with an average recovery rate of 93±0.21
This study investigates the effects of uniform interfacial shear stress, acting parallel to a uniformly heated substrate, on a falling power-law liquid film. In the printing and coating industry, high-speed air is used to apply shear stress to the film surface for drying purposes. To construct a model more relevant to the industrial processing system, the heat loss at the wall-air interface is to be considered, which modifies the heat flux at the solid-liquid interface. Using normal mode stability analysis, an Orr-Sommerfeld eigenvalue problem is constructed. Using the long-wave expansion technique, the onset of instability for Newtonian (n = 1), shear-thinning (n < 1), and shear-thickening films (n > 1) is obtained separately in terms of critical Reynolds number (Re-c). The study reveals that the instability threshold depends on the variation of interfacial shear stress (tau(w)), loss of heat at the wall-air interface (B-w), and the power-law index (n). Thermocapillary (S-mode) instability is discussed through analytical means for the Newtonian film in the limit Re -> 0. In addition, by incorporating Chebyshev's spectral collocation method, the effects of the parameters M (film Marangoni number), B-w (wall film Biot number), B-f (free surface Biot number), and tau(w) in the S-mode instability zone is examined in the arbitrary-wave-number regime for a representative value of the power-law index n. Using the long-wave assumption, a reduced-order model is derived to capture the nonlinear effects. The nonlinear influences of the parameters M, tau(w), B-w, B-f, and n are consistent with the results of the linear study obtained from the normal mode analysis of the Orr-Sommerfeld BVP as well as from the free surface evolution equation.
We present a comprehensive framework for gravity-driven, surfactant-laden thin films flowing over slippery substrates, elucidating how wall slip modifies the coupled hydrodynamics and interfacial transport. A long-wave model is formulated with a conservative bulk-surface mass balance and a Navier slip condition. The Orr-Sommerfeld eigenvalue problem governs the linear regime, while a weighted-residual model captures the nonlinear evolution over a range of equilibrium surfactant coverages, Marangoni strengths, and adsorption kinetics. The analysis predicts a non-monotonic variation of the critical Reynolds number with equilibrium coverage, exhibiting a maximum at intermediate Γ_e, and a slip-induced transition from single- to double-hump solitary structures with increasing Marangoni number, accompanied by attenuated capillary ripples. Under fast adsorption kinetics, the surface field homogenizes, preserving the mean film shape and flux while flattening both the surface concentration Γ and the bulk inventory χ+ hϕ. A spurious interfacial mass growth reported by Pascal et al.(PRF, 2019) and D'Alessio et al.(JFM, 2020) is resolved through a revised surface balance ensuring strict conservation. Wall slip thus emerges as a key control parameter, reducing viscous resistance and mitigating Marangoni back-stress. The slip parameter β is a useful control knob for surfactant-laden films. Slip prevents fragile multi-hump bound states, promoting a single broad crest or an almost flat, uniform sheet by carefully bonding β to wave selection, ripple damping, and the bulk-surface surfactant balance.
An attempt has been made to study the interspecific interaction between two stored-grain insect pests. In the laboratory, Sitophilus oryzae (Linnaeus, 1763) and Tribolium castaneum (Herbst, 1797) were allowed to rear in the same culture box containing healthy wheat grains. S. oryzae with a rostrum feeds on whole grains, whereas T. castaneum without a rostrum feeds on grain powder and often enters grooves inside the grains that S. oryzae had previously attacked. Multiple culture boxes were maintained for observation in the biological oxygen demand incubator at an optimal temperature range of 28 +/- 1 degrees C for 2 months, until the wheat grains were ground into powder. T. castaneum was predominantly detected in the grain powder, while S. oryzae was mostly found to leave the culture. Subsequently, T-tube experiments with this powder or with whole wheat grains and both insect pest species were carried out, wherein S. oryzae was observed to avoid the powder, whereas T. castaneum was attracted to it. Additionally, grain powder underwent microbiological examination using the carbol fuchsin method. This study suggests that controlling S. oryzae automatically reduces T. castaneum, a secondary pest that feeds on food damaged or broken by the former.
