Synthesis and characterization of coordination polymers of polyesters with pendant amino groups

Oligomeric polyester, namely, poly(tetramethylene aspartate) (PTMA), was synthesized from D ,L -aspartic acid and 1,4-butanediol by a melt-condensation technique. Polyester–metal complexes were synthesized by the reaction of PTMA with hydrated acetates of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), Mg(II), Ca(II), Pb(II), and Ce(IV) in DMSO. The polyester–metal complexes were characterized by elemental analysis, IR spectral studies, magnetic susceptibility measurements, and thermogravimetry. The metal ions were found to be six-coordinated with two water molecules as additional ligands besides oxygen and nitrogen atoms of polyester repeating units. Thermogravimetric analysis (TGA) showed that coordination polymers are thermally more stable than is polyester. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 751–759, 1998     

Modification of Microstructure of Starch Extruded With Selected Lipids

Normal corn starch was extruded with palm, peanut and coconut oils; myristic, stearic and behenic acids and three monoglycerides in a C. W. Brabender single screw laboratory extruder at 140°C barrel temperature, 140rpm screw speed and 22% moisture content. Microstructure of extrudates was studied using a scanning electron mircocope. The pore size distribution, pore volumes and shear strengths of the extrudates were also studied. Addition of lipids resulted in modification of pore size distribution and pore volumes depending on the type of lipid. Complexing lipids gave lower pore volumes, smaller size pores, lower porosities and higher shear strengths of the extrudates. Porosity correlated well with the shear strength values.     

The Immunometabolic Roles of Various Fatty Acids in Macrophages and Lymphocytes

Macrophages and lymphocytes demonstrate metabolic plasticity, which is dependent partly on their state of activation and partly on the availability of various energy yielding and biosynthetic substrates (fatty acids, glucose, and amino acids). These substrates are essential to fuel-based metabolic reprogramming that supports optimal immune function, including the inflammatory response. In this review, we will focus on metabolism in macrophages and lymphocytes and discuss the role of fatty acids in governing the phenotype, activation, and functional status of these important cells. We summarize the current understanding of the pathways of fatty acid metabolism and related mechanisms of action and also explore possible new perspectives in this exciting area of research.     

Template-free electrodeposition of highly oriented and aspect-ratio controlled ZnO hexagonal columnar arrays

We report an easy one-step template-free electrodeposition method for preparing large arrays of ZnO hexagonal nanocolumns, vertically oriented on a Au-coated Si substrate. Systematic scanning electron microscopy investigations revealed the potential of this method for obtaining a high degree of verticality and orientation of the nanostructures and for controlling their aspect-ratio in an easy manner. Further structural studies demonstrated that the as-obtained ZnO nanocolumns present a well defined hexagonal symmetry exhibiting an excellent crystallinity.     

Understanding the growth of amorphous SiO2 nanofibers and crystalline binary nanoparticles produced by laser ablation

The pulsed-laser evaporation synthesis of silica nanofibers and crystalline binary nanoparticles is investigated in detail. By careful adjustment of the synthesis parameters one can tailor the product to form high yield nanofibers or binary nanoparticles. Some control on their diameters is also possible through the synthesis parameters. Oxidation of the nanofibers occurs upon exposure to air after the reaction.     

Hopping Conduction in Mn Ion-Implanted GaAs Nanowires

We report on temperature-dependent charge transport in heavily doped Mn(+)-implanted GaAs nanowires. The results clearly demonstrate that the transport is governed by temperature-dependent hopping processes, with a crossover between nearest neighbor hopping and Mott variable range hopping at about 180 K. From detailed analysis, we have extracted characteristic hopping energies and corresponding hopping lengths. At low temperatures, a strongly nonlinear conductivity is observed which reflects a modified hopping process driven by the high electric field at large bias.     

Stress-dependent thermal relaxation effects in micro-mechanical resonators

Thermal relaxation is a key factor in determining the quality factor of micro and nano resonators, which controls the energy dissipation through the coupling of the mechanical and thermal domains. While the literature contains approximate, exact and computational models for quantitative analysis of thermo-elastic coupling, very few techniques are available to ‘tune’ it without changing the material, geometry or operating conditions. In this paper, we develop an analytical model that considers a pre-stress in a flexural resonator to modify the thermal relaxation time and thus increase the quality factor. The effects of length-scale, pre-stress and geometry on the quality factor have been analyzed. The model predicts that significant improvement in terms of dimensionless quality factors is possible by tuning the pre-stress.     

Experimental design of tritium extraction loop from lead lithium eutectic

Effective tritium breeding achievable in Test Blanket Module (TBM) is a major issue for sustainable fusion energy program. Equally important is tritium extraction to recover and recycle tritium back to fusion reactor. Tritium extraction from lead lithium is much more complicated than from purge gas due to low tritium extraction efficiency in transfer step to gas phase and the limitations imposed on space and lead lithium inventory in port cell. Earlier investigations do suggest the preference of packed columns over bubble columns. Theoretical models based on axial dispersion plug flow in liquid and gas proposed for bubble columns and packed columns are reinvestigated for different boundary conditions.This paper highlights the critical issues of experimental design based on tritium extraction efficiency and its impact on recovery loop. Steady state closed loop for absorption and stripping of hydrogen isotopes using inert gas is designed along with the associated auxiliaries.     

Enhanced π-π interactions between a C60 fullerene and a buckle bend on a double-walled carbon nanotube

In situ low-voltage aberration corrected transmission electron microscopy (TEM) observations of the dynamic entrapment of a C₆₀ molecule in the saddle of a bent double-walled carbon nanotube is presented. The fullerene interaction is non-covalent, suggesting that enhanced π-π interactions (van der Waals forces) are responsible. Classical molecular dynamics calculations confirm that the increased interaction area associated with a buckle is sufficient to trap a fullerene. Moreover, they show hopping behavior in agreement with our experimental observations. Our findings further our understanding of carbon nanostructure interactions, which are important in the rapidly developing field of low-voltage aberration corrected TEM and nano-carbon device fabrication.