Preparation and Characterization of Ni-Ferrite Coating on Carbon Steel Coupons

1.IntroductionTheinteractionofhightemperaturewaterwithcarbonsteel(CS)structuralsurfacesundertheprimaryheattransport(PHT)chemistryconditionsresultsintheformationofaprotectivemagnetitefilmwhichhasabilayerstructure.TheoxidelayerclosetometalgrowsintoitduetoO2-movementandoxi-dationofiron.Theouterlayerisformedbyprecipita-tionofFe3O4duetosupersaturationofthecirculat-ingcoolallt.Therelativemagnitudeofthethicknessofthetwolayersandtheirvariationwithtimeareaffectedbymanyfactors.Theporosityofthefilmgi…     

High-Temperature Flow Behavior of SiC-Glass Composites in Compression and Tension

The high-temperature flow behavior of different borosilicate composites was investigated in compression and tension. The flow behavior of composites changed from Newtonian to non-Newtonian as the volume fraction and aspect ratio of reinforcements increased. Generally, platelet/particulate composites exhibited higher tensile elongations compared with short fiber/whisker composites. The tensile ductility increased with decreased volume fraction of reinforcements and temperature. Cavitation in these samples varied across the length, and maximum cavitation occurred near the fracture zone.     

Numerical study of rich catalytic combustion of syngas

The rich catalytic combustion of syngas/air mixtures over platinum has been investigated numerically in a two-dimensional circular channel using steady simulations and detailed hetero-homogeneous chemistry. The channel dimensions are representative of a catalytic monolith. Simulations have been conducted in the pressure range of 1–10 bar and Φ = 3–5 with varying inlet velocities, residence time, H₂/CO ratio and CH₄ percentage. Detailed kinetic studies including the reaction path diagram (RPD) in a plug flow reactor have also been conducted to understand the kinetic interactions between H₂, CO, and CH₄. It has been observed that the homogeneous reaction rates are significant at higher pressures and cannot be neglected, although they were highly localized. The channel temperature significantly affected the relative conversion of H₂ and CO. The kinetic coupling between H₂ and CO oxidation was studied and the reason for the differential consumption of O₂ by the reactants was addressed by analyzing the reaction pathways. The residence time in the channel affected the species oxidation and four operation regimes were identified. Both the water-gas shift reaction and the reverse water-gas shift reaction were observed under varying conditions of pressure and equivalence ratio. The effect of H₂/CO ratio has also been investigated. The present study shows that rich catalytic combustion of syngas is fundamentally different from lean combustion.     

Mineral element composition of spinach

An extensive study has been made on the mineral element compositions of spinach leaves and stems. Twenty two locally grown different spinach samples have been analysed for 16 elements using ICP and atomic absorption spectrophotometric techniques. Both spinach leaves and stems were analysed separately. A detailed elucidation of the inorganic matrix in spinach leaves and stems has been provided. © 1998 SCI.     

Thermal and mechanical properties of polymer‐nanocomposites based on ethylene methyl acrylate and multiwalled carbon nanotube

The ethylene methyl acrylate copolymer (EMA) and multiwalled carbon nanotube (MWNT) based composites were prepared by solution mixing as well as by melt processing of the films obtained after solution mixing. Field emission scanning electron microscopy, transmission electron microscopy, and XRD were used to characterize morphologies of various composites. MWNTs were found to be more dispersed in the composites prepared by melt process after solution process. There was no obvious agglomeration of MWNTs at lower % loading (up to 2.5%) in the polymer matrices especially the composites are prepared solution plus melt mixing and consequently better interaction between MWNTs and EMA matrix was anticipated. XRD and differential scanning calorimetry studied showed that the nanotubes affect the crystallization process and subsequently their role as a nucleating agent was established. These are reflected in the mechanical properties of the composites. Dynamic mechanical analysis showed that the storage modulus of the composites drop very sharply beyond 2.5 wt% of MWNT content with increasing % strain and it reflects the Payne effect (a substantial decrease in the storage modulus of a particle‐reinforced polymer with an increase in the amplitude of dynamic oscillations). The influence of concentration of filler was also realized by frequency sweep experiment. The incorporation of MWNTs in EMA offered a stabilizing effect since onset of degradation occurs at higher temperatures for composites. POLYM. COMPOS., 31:1168–1178, 2010. © 2009 Society of Plastics Engineers     

DNA conjugated SWCNTs enter endothelial cells via Rac1 mediated macropinocytosis

Several applications of single-walled carbon nanotubes (SWCNT) as nanovectors in biological systems have been reported, and several molecular pathways of cellular entry have been proposed. We employed transmission electron microscopy, confocal fluorescent microscopy, and UV-vis spectroscopic analysis to confirm the internalization of DNA-SWCNT in human umbilical vein endothelial cells. Additionally, by using pharmacological inhibitors as well as genetic approaches, we have found that SWCNT is endocytosed through Rac1- GTPase mediated macropinocytosis in normal endothelial cells.     

Probing and repairing damaged surfaces with nanoparticle-containing microcapsules

Nanoparticles have useful properties, but it is often important that they only start working after they are placed in a desired location. The encapsulation of nanoparticles allows their function to be preserved until they are released at a specific time or location, and this has been exploited in the development of self-healing materials and in applications such as drug delivery. Encapsulation has also been used to stabilize and control the release of substances, including flavours, fragrances and pesticides. We recently proposed a new technique for the repair of surfaces called 'repair-and-go'. In this approach, a flexible microcapsule filled with a solution of nanoparticles rolls across a surface that has been damaged, stopping to repair any defects it encounters by releasing nanoparticles into them, then moving on to the next defect. Here, we experimentally demonstrate the repair-and-go approach using droplets of oil that are stabilized with a polymer surfactant and contain CdSe nanoparticles. We show that these microcapsules can find the cracks on a surface and selectively deliver the nanoparticle contents into the crack, before moving on to find the next crack. Although the microcapsules are too large to enter the cracks, their flexible walls allow them to probe and adhere temporarily to the interior of the cracks. The release of nanoparticles is made possible by the thin microcapsule wall (comparable to the diameter of the nanoparticles) and by the favourable (hydrophobic-hydrophobic) interactions between the nanoparticle and the cracked surface.