Investigation of single wall carbon nanotubes electrical properties and normal mode analysis: Dielectric effects

Besides thermodynamic information, vibration can identify modes of a molecule by comparison of the spectroscopy and parameterize force field. By the application of group theory with the state of projection operators, a systematic method for getting the vibrational model of molecules such as the (3, 0), (4, 0), (5, 0) nanotubes was proposed. The U matrix from the combination of primitive’s harmonic vibrations was calculated and the effect of dielectric constants on the mechanism of these vibrations in nanotubes was studied. We found that in the high dielectrics the frequency of vibration has alternative behavior, however by the decreasing of the dielectrics, this behavior change to stable situation of geometry. The calculated data shown in Tables and Figures are in correspondence with some behavior of nanotubes.     

SnO2 nanowires mixed nanodendrites for high ethanol sensor response

Mixed morphology of SnO₂ nanowires and nanodendrites was synthesized on the gold-coated alumina substrates by carbothermal reduction of SnO₂ in closed crucible. The products were characterized by scanning electron microscopy, x-ray diffractometer, and transmission electron microscopy. Results showed the SnO₂ nanowires and the SnO₂ nanodendrites branched out from the main nanowires. Both SnO₂ nanostructures were pure tetragonal rutile structure. The nanowires were grown in [101] and directions with the diameter of 50–150 nm and the length of a few 10 μm. The nanodendrites were about 100–300 nm in diameter. The growth mechanism of the SnO₂ nanostructures was also discussed. Characterization of ethanol gas sensor, based on the mixed morphology of the SnO₂ nanostructures, was carried out. The optimal temperature was about 360 °C and the sensor response was 120 for 1000 ppm of ethanol concentration.     

Catalytic Antibodies: A New Class of Transition-State Analogues Used to Elicit Hydrolytic Antibodies

The design and generation of selective catalysts is an important aim of chemists and biologists. A number of successful strategies have emerged, including the synthesis and derivatization of synthetic hosts, the chemical modification and site-directed mutagenesis of enzymes, and the attenuation of natural enzyme activities in organic solvents. Since 1986 several laboratories have exploited the immune system to generate selective catalysts capable of catalyzing a wide range of chemical transformations. These include acyl transfer, β-elimination, carbon—carbon bond-forming, carbon—carbon bond-cleaving, porphyrin metalation, peroxidation, and redox reactions. The variety and number of transformations catalyzed by antibodies in this short period of time is testament to the versatility and power of the method in generating selective catalysts for applications in chemistry, biology, and medicine. Here we report the use of a new class of uncharged transition-state analogues for generating antibodies capable of catalyzing ester and carbonate hydrolysis. These antibodies are compared to those raised against tetrahedral phosphate and phosphonate transition-state analogues.