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Theoretical determinations of the thermal rate constants and product energy distributions of the N2+O→NO+N reaction, which plays a crucial role in hydrocarbon air combustion and high temperature air chemistry, are carried out using a quasiclassical trajectory method. An analytical fit of the lowest 3A′ potential energy surface of this reaction based on the CCI ab initio data is obtained. The trajectory study is done on this surface and an analytical 3A″ surface proposed by Gilibert et al. [J. Chem. Phys. 97, 5542 (1992)]. The thermal rate constants computed from 3000 to 20 000 K are in good agreement with the available experimental data. In addition, the dependence of the rate constant on the N2 internal state is studied. It is found that a low vibrational excitation can reduce the rate constant of this reaction by a factor of 3. Also, we investigate the effect of the N2 vibrational state on the product NO vibrational distribution, and it is found that at low N2 vibrational states, the NO vibrational distribution is nearly Boltzmann. However, at N2(v≳10), the product distribution is almost uniform at low energy levels.

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A detailed quasiclassical trajectory study of the O2+N→NO+O reaction is performed based on ab initio potential-energy surfaces of the 2A′ and 4A′ states. The study is aimed at generating a database of thermally averaged and O2 state-specific rate constants needed for accurate simulations of NO kinetics in high-temperature flow processes. The rate constants obtained show good agreement with the available experimental data and with other quasiclassical trajectory calculations. It is found that the reactant internal energy of the O2+N→NO+O reaction is less effective in enhancing the rate than in the N2+O→NO+N reaction. An analysis of the product vibrational energy shows that NO formed by the O2+N→NO+O reaction has a non-Boltzmann distribution. It is also found that the most populated NO vibrational level is determined by the reactant vibrational energy, while the terminal slope of the NO vibrational distribution is a strong function of the reactant translational temperature.

The effect of the plasma on heating the growth substrate in plasma enhanced chemical vapor deposition (PECVD) of carbon nanotubes is characterized for the first time. This effect, which is commonly ignored in the nanotube/nanofiber literature, is the sole heating mechanism in this work for catalyst pretreatment and growth of straight and vertically aligned multiwalled carbon nanofibers. Significant temperatures, as high as 700 °C, are induced from a C2H2:NH3 direct current (dc) plasma with no other heat source present. To model the behavior of the plasma-heated substrate platform, we have developed a 1-D dc discharge model that incorporates a cathode platform energy balance, including ion bombardment, thermal radiation, and solid and gas conduction. The predicted gas-phase species present are correlated with the morphology of nanofibers grown by exclusive plasma heating as well as by heating from plasma in combination with a conventional resistive heater. The understanding of plasma heating and its accurate modeling are essential for reactor design for wafer scale production of vertically aligned nanofibers.

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Anticancer role of andrographolide is well documented. To find novel potent derivatives with improved cytotoxicity than andrographolide on cancer cells, two series of di-spiropyrrolidino- and di-spiropyrrolizidino oxindole andrographolide derivatives prepared by cyclo-addition of azomethine ylide along with sarcosine or proline (viz. sarcosine and proline series respectively) and substitution of different functional groups (-CH3, -OCH3 and halogens) were examined for their cytotoxic effect on a panel of six human cancer cell lines (colorectal carcinoma HCT116 cells, pancreatic carcinoma MiaPaCa-2 cells, hepatocarcinoma HepG2 cells, cervical carcinoma HeLa cells, lung carcinoma A549 and melanoma A375 cells). Except halogen substituted derivatives of proline series (viz. CY2, CY14 and CY15 for Br, Cl and I substitution respectively), none of the other derivatives showed improved cytotoxicity than andrographolide in the cancer cell lines examined. Order of cytotoxicity of the potent compounds is CY2>CY14>CY15>andrographolide. Higher toxicity was observed in HCT116, MiaPaCa-2 and HepG2 cells. CY2, induced death of HCT116 (GI50 10.5), MiaPaCa-2 (GI50 11.2) and HepG2 (GI50 16.6) cells were associated with cell rounding, nuclear fragmentation and increased percentage of apoptotic cells, cell cycle arrest at G1 phase, ROS generation, and involvement of mitochondrial pathway. Upregulation of Bax, Bad, p53, caspases-3,-9 and cleaved PARP; downregulation of Bcl-2, cytosolic NF-κB p65, PI3K and p-Akt; translocation of P53/P21, NF-κB p65 were seen in CY2 treated HCT116 cells. Thus, three halogenated di-spiropyrrolizidino oxindole derivatives of andrographolide are found to be more cytotoxic than andrographolide in some cancer cells. The most potent derivative, CY2 induced death of the cancer cells involves ROS dependent mitochondrial pathway like andrographolide.