Pengmei Lu

TX Cnc AS A MEMBER OF THE PRAESEPE OPEN CLUSTER

We present B-, V-, and I-band CCD photometry of the W UMa-type binary system TX Cnc, which is a member star of the Praesepe open cluster. Based on the observations, new ephemeris and a revised photometric solution of the binary system were derived. Combined with the results of the radial velocity solution contributed by Pribulla et al., the absolute parameters of the system were determined. The mass, radius, and luminosity of the primary component are derived to be 1.35 {+-} 0.02 M {sub sun}, 1.27 {+-} 0.04 R {sub sun}, and 2.13 {+-} 0.11 L {sub sun}. Those for the secondary star are computed as 0.61 {+-} 0.01 M {sub sun}, 0.89 {+-} 0.03 R {sub sun}, and 1.26 {+-} 0.07 L {sub sun}, respectively. Based on these results, a distance modulus of (m - M) {sub V} = 6.34 {+-} 0.05 is determined for the star. It confirms the membership of TX Cnc to the Praesepe open cluster. The evolutionary status and the physical nature of the binary system are discussed compared with the theoretical model.

Application of surface-modified carbon powder in microbial fuel cells

Abstract The catalytic activity of surface-modified carbon powder, Vulcan XC-72R (XC), for the oxygen reduction reaction (ORR) at an air cathode in a microbial fuel cell (MFC) has been investigated. The effects of treatment with different chemicals such as nitric acid and ammonia on the chemical characteristics of XC were studied. The catalysts were characterized by Fourier transform infrared spectroscopy (FTIR), Boehm titration, and X-ray photoelectron spectroscopy. FTIR analysis showed that the functional groups of the materials were changed by chemical treatment, with nitric acid causing the introduction of oxygen-containing groups, and ammonia leading to the introduction of nitrogen-containing groups. Electrochemical measurements of MFCs containing various modified carbon materials as ORR catalysts were performed, and the results showed that chemically modified carbon materials are promising catalysts in MFCs.

Double-lipase catalyzed synthesis of kojic dipalmitate in organic solvents

Kojic dipalmitate(KDP) was synthesized by the way of esterification of palmitic and kojic acids in organic solvent, with double-lipase as the biocatalyst. Four commercially available lipases(Amano PS, Novozym 435, Lipozyme TL IM and Lipozyme RM IM) were used to group six double-lipase combinations. These combinations were studied and Amano PS-Novozym 435 was found to have the best efficiency and was selected for optimizing the reaction conditions. The optimal reaction conditions were that the mass ratio of Amano PS to Novozyme 435 1:1.5, stirring speed of 500 r/min, substrates molar ratio of 1:2, 50 °C, 5%(mass fraction) catalyst dosage of kojic acid quantity and using acetone as co-solvent. Under these conditions, the diesterification of C5 and C7 hydroxyl groups of kojic acid molecule could be well catalyzed by double-lipase and realize a high KDP yield of 85%.