排序方式: 共有24条查询结果,搜索用时 453 毫秒
21.
Faruque M. Hossain B.Z. Dlugogorski E.M. Kennedy I.V. Belova Graeme E. Murch 《Solid State Communications》2010,150(17-18):848-851
The electronic, optical and bonding properties of MgCO3 (magnesite, rhombohedral calcite-type structure) are calculated using a first-principles density-functional theory (DFT) method considering the exchange-correlation function within the local density approximation (LDA) and the generalized gradient approximation (GGA). The indirect band gap of magnesite is estimated to be 5.0 eV, which is underestimated by ~1.0 eV. The fundamental absorption edge, which indicates the exact optical transitions from occupied valence bands to the unoccupied conduction band, is estimated by calculating the photon energy dependent imaginary part of the dielectric function using scissors approximations (rigid shift of unoccupied bands). The optical properties show consistent results with the experimental calcite-type structure and also show a considerable optical anisotropy of the magnesite structure. The density of states and Mulliken population analyses reveal the bonding nature between the atoms. 相似文献
22.
Golam Faruque Khan 《Electroanalysis》1997,9(4):325-329
A printed amperometric glucose sensor based on glucose oxidase adsorbed on crystals of tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) is described. The sensitivity and the stability of the sensor are affected by the binder and solvent used for the preparation of the GOD.TTF-TCNQ paste. The sensors are continuously used in a flow injection analysis (FIA) system under continuous polarization at 0.15 V (vs Ag/AgCl) at 37°C. The developed sensors exhibit a large response current, an extended linear range and oxygen independence. The sensors can be used for more than 3 months. The GOD.TTF-TCNQ paste is suitable for the preparation of planar sensor by screen printing method. 相似文献
23.
Golam Faruque Khan 《Electroanalysis》1997,9(7):533-536
A novel fabrication of an amperometric glucose sensor by layer after layer approach is described. The sensor electrode is fabricated by arranging a layer of Pt black, a layer of glucose oxidase (GOD) and a layer of stabilizer gelatin on a shapable electro-conductive (SEC) film surface. Finally, the dried layered-assembly is cross-linked by exposing to a diluted glutaraldehyde solution. The performance of the developed sensor is evaluated by a FIA system at 37°C and under a continuous polarization at 0.4 V (vs. Ag/AgCl). The sensitivity of the sensor was dependent on the amount of GOD loaded. The highest sensitivity (3.6 μA/mM cm−2) of the sensor was obtained at a GOD loading of 160 μg/cm2, and the linear dynamic range was extended to 80 mM level when the sensor was covered with a polycarbonate membrane. The sensor shows an extremely stable response for several weeks and a storage stability of over 2 years. 相似文献
24.
Faruque M. Hossain Leigh Sheppard Graeme E. Murch 《Journal of Physics and Chemistry of Solids》2008,69(7):1820-1828
The optical properties of rutile and anatase titanium dioxide (TiO2) are calculated from the imaginary part of the dielectric function using pseudopotential density functional method within its generalized gradient approximation (GGA) and a scissors approximation. The fundamental absorption edges calculated for the unit cell of both rutile and anatase are consistent with experimentally reported results of single crystal rutile and anatase TiO2 and with previous theoretical calculations. A significant optical anisotropy is observed in the anatase structure which holds promise for investigating the band gap modification with better visible-light response and provides a reliable foundation for addressing the effect of impurities on the fundamental absorption edge/band gap of anatase TiO2. Further calculations on the electronic structure and the optical properties of C-, N-, and S-doped anatase TiO2 are performed. The results are analyzed and discussed in terms of optical anisotropy and scissors approximations. 相似文献