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In the present work, we have synthesized rare-earth ion modified Bi4−xRExTi2Fe0.7Co0.3O12−δ (RE = Dy, Sm, La) multiferroic compounds by the conventional solid-state route. Analysis of X-ray diffraction by Rietveld refinement confirmed the formation of a polycrystalline orthorhombic phase. The morphological features revealed a non-uniform, randomly oriented, plate-like grain structure. The peaks evident in the Raman spectra closely corresponded to those of orthorhombic Aurivillius phases. Dielectric studies and impedance measurements were carried out. Asymmetric complex impedance spectra suggested the relaxation of charge carriers belonging to the non-Debye type and controlled by a thermally activated process. Temperature-dependent AC conductivity data showed a change of slope in the vicinity of the phase transition temperature of both magnetic and electrical coupling natures. Based on the universal law and its exponent nature, one can suppose that the conduction process is governed by a small polaron hopping mechanism but significant distortion of TiO6 octahedral. The doping of the A-sites with rare-earth element ions and changes in the concentrations of Fe and Co ions located on the B-sites manifested themselves in saturated magnetic hysteresis loops, indicating competitive interactions between ferroelectric and canted antiferromagnetic spins. The magnetic order in the samples is attributed to pair-wise interactions between adjacent Fe3+–O–Fe3+, Co2+/3+–O–Co3+/2+, and Co2+/3+–O–Fe3+ ions or Dzyaloshinskii–Moriya interactions among magnetic ions in the adjacent sub-lattices. As a result, enhanced magnetoelectric coefficients of 42.4 mV/cm-Oe, 30.3 mV/cm-Oe, and 21.6 mV/cm-Oe for Bi4−xDyxTi2Fe0.7Co0.3O12−δ (DBTFC), Bi4−xLaxTi2Fe0.7Co0.3O12−δ (LBTFC), and Bi4−xSmxTi2Fe0.7Co0.3O12−δ (SBTFC), respectively, have been obtained at lower magnetic fields (<3 kOe). The strong coupling of the Aurivillius compounds observed in this study is beneficial to future multiferroic applications. [ABSTRACT FROM AUTHOR]

The time-lag method is the most useful technique to determine gas permeability, diffusivity, and solubility. However, it is difficult to evaluate the transport properties of the membrane accurately because gas permeability depends on the technique used to assess gas flow. The significance of the present study is to design an economic isochoric apparatus to accurately measure micro-range gas flow rates ranging from 10−6 to 10 cm3(STP) s−1. A strategic procedure is demonstrated to eliminate possible artifacts while conducting the gas permeation experiments, including utilizing downstream pressure rise profiles to identify nanoscale defects as well as transient and steady-state permeation. An indigenous apparatus was developed to estimate the polymeric intrinsic properties of the dense and thin-film composite membranes. The device has been successfully used to measure the gas permeation flow rate ranging from 1 × 10−5 to 1 × 10−1cm3 (STP) s−1, which indicates the broad applicability and reproducibility of the data suggesting the reliability of the designed apparatus. Permeation flow rates of binary mixtures of CO2/CH4 through the defect-free membranes were compared with the numerical estimations to validate the measured transport properties. [ABSTRACT FROM AUTHOR]

Multidrug resistance (MDR) is a major obstacle in cancer chemotherapy. P‐glycoprotein (P‐gp) one of the ATP‐binding cassette (ABC) transporters plays an important role in MDR. In this study, we examined the sensitizing property of andrographolide (Andro) to reverse MDR in the drug‐resistant KBChR 8‐5 cells. Andro exhibited increased cytotoxicity in a concentration‐dependent manner in the P‐gp overexpressing KBChR 8‐5 cells. Furthermore, Andro showed synergistic interactions with PTX and DOX in this drug‐resistant cells. Andro co‐administration enhanced PTX‐ and DOX‐induced cytotoxicity and reduced cell proliferation in the MDR cancer cells. Moreover, reactive oxygen species (ROS) were elevated with a decrease in the mitochondrial membrane potential (MMP) during Andro and chemotherapeutic drugs combination treatment in the drug‐resistant cells. Furthermore, Andro and PTX‐induced cell cycle arrest was observed in the drug‐resistant cell. We also noticed that the expression of ABCB1 and AKT were downregulated during Andro (4 µM) treatment. Furthermore, Andro treatment enhanced the expression of caspase 3 and caspase 9 in the combinational groups that support the enhanced apoptotic cell death in drug‐resistant cancer cells. Therefore, the results reveal that Andro plays a role in the reversal of P‐gp‐mediated MDR in KBChR 8‐5 cells which might be due to regulating ABCB1/AKT signaling pathway. Significance statement: ATP‐binding cassette (ABC) transporters‐mediated multidrug resistance (MDR) is a major hindrance during cancer treatment. Efflux mechanism of P‐glycoprotein (P‐gp) decreases bioavailability and efficacy of chemotherapeutic drugs. Already known inhibitors of P‐gp exhibit higher toxicity to the untargeted cells. Phytochemicals have great potential to reverse the MDR mechanism in cancer cells with less toxicity. Andrographolide (Andro), a phytochemical of Andrographis paniculata, enhanced the efficacy of the chemotherapeutic drugs and reverses drug resistance in MDR cancer cells. Therefore, Andro can be considered as a potent candidate to overcome MDR after preclinical and clinical validations. [ABSTRACT FROM AUTHOR]