Effects of <Emphasis Type="Italic">A.marina</Emphasis>-Derived Isoquercitrin on TNF-Related Apoptosis-Inducing Ligand Receptor (TRAIL-R) Expression and Apoptosis Induction in Cervical Cancer Cells

TNF-related apoptosis-inducing ligand (TRAIL) is an anticancer agent, which has greater apoptosis inducing capacity, but most of the cancer cells become resistant to TRAIL-induced apoptosis. The combined treatment of TRAIL with natural products could restore the cancer cell sensitivity to recombinant human TRAIL (rhTRAIL) protein and might enhance the TNF-related apoptosis-inducing ligand receptor (TRAIL-R) expression. This investigation was aimed to isolate flavonoids from leaves of Avicennia marina and evaluate their potential for sensitization of rhTRAIL in human cervical cancer cells (SiHa). The methanolic extract of A.marina leaves were purified and structure was elucidated as isoquercitrin by NMR and LC-MS analysis. Isolated isoquercitrin showed cytotoxicity against SiHa cell line at IC₅₀ of 980 μM. Messenger RNA (mRNA) expression of TRAIL-Rs was quantified by qRT-PCR, combination of isoquercitrin, and/or rhTRAIL increased TRAIL-R1 and TRAIL-R2 gene expression by 7 folds and 4 folds, respectively. Also, FACS assay revealed that combined treatment has increased the early apoptosis up to 7.24%. In the present study, we found that isoquercitrin enhances the mRNA expression of TRAIL-Rs, but the percentage of apoptosis was meager, possibly due to the influence of other anti-apoptotic proteins.     

The effect of length of single‐walled carbon nanotubes (SWNTs) on electrical properties of conducting polymer–SWNT composites

DC conductivity of conjugated polymer‐single‐walled carbon nanotube (SWNT) composite films has been measured for different SWNT concentrations. The composite was prepared by dispersing SWNTs in the poly (3‐octylthiophene), P3OT matrix already dissolved in xylene. The conductivity of the composite films showed a rapid increase as the SWNT concentration increases beyond a certain value. This behavior is explained in terms of percolating paths provided by the SWNTs in the volume of polymer matrix. To investigate the effect of length of nanotubes on the percolation conductivity, different SWNT samples were employed with similar diameter but varying tube lengths. It was found that the conductivity of the composite films is strongly dominated by the length of the nanotubes. Lower percolation limit and high conductivity value of composite films is observed for longer nanotubes. Furthermore, the conductivity is observed to be dependent on the size of the host polymer molecule also. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 89–95, 2010     

Synthesis,electrical and thermal properties of Bi4V2−xMexO11 (Me=Nb,Zr, Y and Cu with x = 0.0 and 0.06) ceramics

Polycrystalline ceramic samples of Bi₄V_2?xMe_xO₁₁ (Me=Nb, Zr, Y and Cu and x = 0.0 and 0.06) have been synthesized by standard solid state reaction method using high purity oxides. The formation of the compounds have been analysed by X-ray diffraction method. The dielectric constant, dielectric loss and AC conductivity as a function of frequency and temperature have been measured. The dielectric studies indicate that the material is highly lossy, and hence, its AC conductivity increases with the increase of temperature. The DC conductivity of material has been measured as a function of temperature from room temperature to 723 K and its activation energy was calculated using the relation σ = σ ₀exp (?E _a/kT). The modulated differential scanning calorimetry has been used to investigate the effect of substitution on the phase transition (heat capacity and heat flow) of the compounds. The results are discussed in detail.     

Tuning electrochemical potential of LiCoO2 with cation substitution: first-principles predictions and electronic origin

With a goal to improve the performance of LiCoO₂ as a cathode material in Li-ion batteries, we simulate substitution of various elements (X = Be, Mg, Al, Ga, Si and Ti) for Co using first-principles density functional theory and predict changes in its electrochemical potential. While the electrochemical potential of LiCoO₂ is enhanced with substitution of Be, Mg, Al and Ga for Co, an opposite effect is predicted of Si and Ti substitution. We determine the electronic origin of these changes in electrochemical potential using (a) Bader method of topological analysis of charge density, (b) partial density of electronic states to estimate oxidation states of metal and oxygen, and charge re-distribution upon lithiation. We find that the distribution of electronic charge donated by Li is influenced by the nature of the X–O bond. A larger electron transfer to O (in XO₆ octahedron) upon lithiation leads to stronger Li intercalation and thereby higher electrochemical voltage. Our findings provide a platform for a rational design of cathode materials in Li batteries with enhanced voltage.     

Experimental study of convection in a model Czochralski crucible using liquid crystal thermography

Steady state temperature distribution in a model Czochralski crucible has been mapped by liquid crystal thermography (LCT). The crucible is a water-filled glass beaker. Water is used as the test fluid because of ease of experimentation, as well as the availability of correct thermo-physical properties. In addition, the Prandtl number of water matches those of molten oxides. A copper cylinder whose diameter is smaller than that of the beaker is placed centrally at the water surface. Convection patterns are set up by applying constant temperature difference between the crucible wall and the cylinder surface, in the temperature range of the liquid crystals. The cylinder is given a fixed rotation, thus creating mixed convection conditions in the test fluid. The LCT images recorded in the present study clearly reveal convective rolls, and the interaction of buoyancy-driven convection in the crucible with cylinder rotation. The resulting temperature distributions match numerical simulation quite well. The pure buoyancy and pure rotation experiments result in axisymmetric temperature fields, while in mixed convection, the field is unsteady and three dimensional.     

Symmetric marching technique for the poisson equation. I. Dirichlet boundary conditions

The symmetric marching technique has been developed to solve the Poisson equation with Dirichlet boundary conditions. The method has been combined with a mesh refinement technique, which is used as an appropriate interpolation scheme to obtain a solution of the problem on finer grids. The effectiveness of the method has been demonstrated by solving some test examples.