Peristaltic motion of two immiscible viscous incompressible fluids in a circular tube is studied in pumping and copumping ranges under long-wavelength and low-Reynoldsnumber assumptions. The effect of the peripheral-layer viscosity on the time-averaged flux and the mechanical efficiency is studied. The formation and growth of the trapping zone in the core and the peripheral layer are explained. It is observed that the bolus volume in the peripheral layer increases with an increase in the viscosity ratio. The limits of the time-averaged flux $\bar{Q}$ for trapping in the core are obtained. The trapping observed in the peripheral layer decreases in size with an increase in $\bar{Q}$ but never disappears. The development of the complete trapping of the core fluid by the peripheral-layer fluid with an increase in the time-averaged flux is demonstrated. The effect of peripheral-layer viscosity on the reflux layer is investigated. It is also observed that the reflux occurs in the entire pumping range for all viscosity ratios and it is absent in the entire range of copumping.

Peristaltic transport of two-layered power-law fluids in axisymmetric tubes is studied. Use of the power-law fluid model permits independent choice of shear thinning, shear thickening, or Newtonian fluids for the core and the peripheral layer. The interface between the two layers is determined from a transcendental equation in the core radius. The variation of the time-mean flow Q with the pressure rise or drop over one wavelength delta p is studied. It is observed that a negative time-mean flow is achieved under free pumping (delta p = 0) for the wave forms considered here if one of the peripheral layer and core fluids is non-Newtonian. The rheology of the peripheral layer fluid is a dominant factor in producing a negative or positive mean flow. It is noticed that a sinusoidal wave always yields a positive mean flow for power-law fluids. The trapped bolus volume for sinusoidal peristaltic wave is observed to decrease with an increase in the rate of shear thinning of the core and the peripheral layer fluids.

Resveratrol (RES) and genistein (GEN) are the dietary natural products known to possess chemopreventive property and also the ability to repair DNA damage induced by mutagens/carcinogens. It is believed that the therapeutic activity of these compounds could be primarily due to their interaction with nucleic acids but detailed reports are not available. We here explore the interaction of these drugs with nucleic acids considering DNA and RNA as a potential therapeutic target. The interaction of RES and GEN has been analysed in buffered solution with DNA [saline sodium citrate (SSC)] and RNA [tris ethylene diammine tetra acetic acid (TE)] using UV-absorption and Fourier transform infrared (FTIR) spectroscopy. The UV analysis revealed lesser binding affinity with nucleic acids at lower concentration of RES (P/D = 5.00 and 10.00), while at higher drug concentration (P/D = 0.75, 1.00 and 2.50) hyperchromic effect with shift in the lambda(max) is noted for DNA and RNA. A major RES-nucleic acids complexes was observed through base pairs and phosphate backbone groups with K = 35.782 M(-1) and K = 34.25 M(-1) for DNARES and RNA-RES complexes respectively. At various concentrations of GEN (P/D = 0.25, 0.50, 0.75, 1.00 and 2.50) hyperchromicity with shift in the lambda(max) from 260-->263 nm and 260--> 270 nm is observed for DNA-GEN and RNA-GEN complexes respectively. The binding constant (from UV analysis) for GEN-nucleic acids complexes could not be obtained due to GEN absorbance overlap with that of nucleic acids at 260 nm. Nevertheless a detailed analysis with regard to the interaction of these drugs (RES/GEN) with DNA and RNA could feasibly be understood by FTIR.

Time correlated Single Photon Counting study (TCSPC) was performed for the first time to evaluate the effect of resveratrol (RES) and genistein (GEN) at 10-100 microM and 10-150 microM respectively, in modulating the DNA conformation and the variation induced due to intercalation by the dyes, ethidium bromide (EtBr) and acridine orange (AO). It is demonstrated using UV-absorption and fluorescence spectroscopy that RES and GEN, at 50 microM and 100 microM respectively can bind to DNA resulting in significant de-intercalation of the dyes, preventing their further intercalation within DNA. Hyperchromicity with red/blue shifts in DNA when bound to dyes was reduced upon addition of RES and GEN. DNA-dependent fluorescence of EtBr and AO was quenched in the presence of RES by 87.97% and 79.13% respectively, while similar quenching effect was observed for these when interacted with GEN (85.52% and 83.85%). It is found from TCSPC analysis that the higher lifetime component or constituent of intercalated dyes (tau(2), A (2)) decreased with the subsequent increase in smaller component or constituent of free dye (tau(1), A (1)) after the interaction of drugs with the intercalated DNA. Thus these findings signify that RES and GEN can play an important role in modulating DNA intercalation, leading to the reduction in DNA-directed toxicity.

No abstract

No abstract

No abstract

No abstract