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991.
利用密度泛函理论通过计算吸附能量、HOMO/LUMO能隙变化、电荷转移、结构扭曲等研究二氧化氮分子在B12N12纳米笼的吸附.此外,通过计算B12N12的电子结合能、Gibbs自由能、态密度和分子表面的静电势研究其稳定性和其它特性.B12N12纳米笼吸附二氧化氮显示三种构型.B12N12团簇的HOMO/LUMO能隙变化对二氧化氮分子的存在非常敏感,从自由团簇的6.84 eV降为NO2/团簇稳定团簇的3.23 eV.团簇的导电性被极大地提高,表明B12N12纳米簇可能是潜在的二氧化氮气体分子检测传感器. 相似文献
992.
S. Zerroug F. Ali Sahraoui N. Bouarissa 《Applied Physics A: Materials Science & Processing》2009,97(2):345-350
Using first principles total energy calculations within the full-potential linearized augmented plane wave method, we have
studied the structural and electronic properties of yttrium nitride (YN) in the three phases, namely wurtzite, caesium chloride
and rocksalt structures. The calculations are performed at zero and under hydrostatic pressure. In agreement with previous
findings, it is found that the favored phase for YN is the rocksalt-like structure. We predict that at zero pressure YN in
the rocksalt structure is a semiconductor with an indirect bandgap of 0.8 eV. A phase transition from a rocksalt to a caesium
chloride structure is found to occur at ∼134 GPa. Besides, a transition from an indirect (Γ−X) bandgap semiconductor to a direct (X−X) one is predicted at pressure of ∼84 GPa. For the electron effective mass of rocksalt YN, these are the first results, to
our knowledge. The information derived from the present study may be useful for the use of YN as an active layer in electronic
devices such as diodes and transistors. 相似文献
993.
A new polymeric oxidizing reagent was prepared by supporting periodic acid on poly(1,4-phenylene-2,5-pyridine dicarboxyamide). This polymeric reagent was used for the selective oxidation of primary benzylic alcohols to the corresponding benzaldehydes in CH3CN at reflux conditions.Excellent selectivity was observed between primary benzyl alcohols and secondary ones as well as non-benzylic alcohols in the oxidation reactions.Allylic alcohols were also converted to the corresponding aldehydes with good yields. 相似文献
994.
995.
Ali Akbar Ashkarran 《Applied Physics A: Materials Science & Processing》2012,107(2):401-410
Ag:ZnO hybrid nanostructures were successfully prepared by a twice arc discharge method in liquid. The visible light photocatalytic
activities were successfully demonstrated for the degradation of Rhodamine B (Rh. B), Methyl orange (MO), and Methylene blue
(MB) as standard organic compounds under the irradiation of 90 W halogen light for 2 h. The Ag:ZnO nanostructures were characterized
by X-Ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet-visible
absorption spectroscopy (UV-Vis). The results revealed that the Ag:ZnO nanostructures extended the light absorption spectrum
toward the visible region and significantly enhanced the Rh. B photodegradation under visible light irradiation. 3 mM Ag:ZnO
nanostructures exhibited highest photocatalytic efficiency. It has been confirmed that the Ag:ZnO nanostructures could be
excited by visible light (E<3.3 eV). The significant enhancement in the Ag:ZnO nanostructures photocatalytic activity under visible light irradiation
can be ascribed to the effect of physisorbed noble metal Ag by acting as electron traps in ZnO band gap. A mechanism for photocatalytic
degradation of organic pollutant over Ag:ZnO photocatalyst was proposed based on our observations. 相似文献
996.
Eugenol, the major constituent of clove oil, has been widely used for its anesthetic and analgesic action in dentistry. Eugenol exhibits pharmacological effects on almost all systems and our aim is to review the research work that has identified these pharmacological actions. Eugenol possesses significant antioxidant, anti-inflammatory and cardiovascular properties, in addition to analgesic and local anesthetic activity. The metabolism and pharmacokinetics of the compound in humans have been studied. Eugenol has also been used as a penetration enhancer. The compound is a very promising candidate for versatile applications, and the design of new drugs based on the pharmacological effects of eugenol could be beneficial. 相似文献
997.
Firouzeh Nemati Mehrnoosh Golmohammadi Afkham Ali Elhampour 《Green Chemistry Letters and Reviews》2014,7(1):79-84
Sulfonic acid-functionalized silica-coated nano-Fe3O4particles (Fe3O4@SiO2–SO3H) serve as a novel heterogeneous catalyst for the synthesis of acylals by direct condensation of aldehydes with acetic anhydride under solvent-free conditions at room temperature in short reaction times and excellent yields. The catalyst could be easily separated from the final product using an external magnet and reused several times without consequential loss of reactivity. 相似文献
998.
Javad?AzizianEmail author Ali R.?Karimi Hamedeh?Arefrad Ali A.?Mohammadi Mohammad R.?Mohammadizadeh 《Monatshefte für Chemie / Chemical Monthly》2004,135(6):729-733
Summary. We report on the addition of dialkyl acetylenedicarboxylate to 1-alkylisatins or tryptanthrine in the presence of triphenylphosphine which leads to highly functionalised novel unsaturated -spirolactones. 相似文献
999.
1000.
Parasteh Pirasteh Ali Soltani Lazhar Haji Nicolas Errien 《Applied Surface Science》2006,253(4):1999-2002
In order to understand the optical loss mechanisms in porous silicon based waveguides, structural and optical studies have been performed. Scanning and transmission electron microscopic observations of porous silicon layers are obtained before and after an oxidation process at high temperature in wet O2. Pore size and shape of heavily p-type doped Si wafers are estimated and correlated to the optical properties of the material before and after oxidation. The refractive index was measured and compared to that determined by the Bruggeman model. 相似文献