Hengyang Normal University

About: Hengyang Normal University is a education organization based out in Hengyang, China. It is known for research contribution in the topics: Graphene & Adsorption. The organization has 1087 authors who have published 1280 publications receiving 13850 citations. The organization is also known as: Hengyang Teachers' College & Héngyáng Shīfàn Xuéyuàn.

Determination of Trace Copper by Adsorptive Voltammetry Using a Multiwalled Carbon Nanotube Modified Carbon Paste Electrode

Abstract: A new method for the determination of trace copper was described. A multiwalled carbon nanotube modified carbon paste electrode was prepared and the adsorptive voltammetric behavior of copper-alizarin red S (ARS) complex at the modified electrode was investigated. By use of the second-order derivative linear sweep voltammetry, it was found that in 0.04 mol/L acetate buffer solution (pH 4.2) containing 4×10−6 mol/L ARS, when accumulation potential is 0 mV, accumulation time is 60 s and scan rate is 100 mV/s, the complex can be adsorbed on the surface of the electrode, yielding one sensitive reduction peak at −172 mV (vs. SCE). The peak current of the complex is proportional to the concentration of Cu(II) in the range of 2.0×10−11–4.0×10−7 mol L−1 with a detection limit (S/N=3) of 8.0×10−12 mol/L (4 min accumulation). The proposed method was successfully applied to the determination of copper in biological samples with satisfactory results, the recoveries were found to be 96%–102%.

Refined Bohr inequality for bounded analytic functions

Abstract: In this article, by combining appropriate refined Bohr's inequalities with some techniques concerning bounded analytic functions defined in the unit disk, we generalize and improve several Bohr-type inequalities for such functions.

Electronic, magnetic and dielectric properties of multiferroic MnTiO3

Abstract: The ground-state structural, electronic, magnetic, optical and dielectric properties of MnTiO3 are calculated using density functional theory within the generalized gradient approximation. The structure parameters obtained agree well with experimental results. The electronic structure results show that the G-type antiferromagnetic phase of LN-type MnTiO3 has an indirect band gap of 0.85 eV. The calculated local magnetic moment of Mn ion is 4.19 μB. The calculated Born effective charges (BECs, denoted by tensor Z*) show that the Z* of Ti and O atoms are significantly and anomalously large. Interestingly, ferroelectric spontaneous polarization of large magnitude is predicted to be along [111] direction with a magnitude of 87.95–105.22 μC/cm2. B-site Ti ions in 3 d0 state dominate ferroelectric polarization of multiferroic MnTiO3, whereas A-site Mn ions having partially filled 3 d5 orbitals are considered to contribute to its antiferromagnetic properties. Furthermore, it is predicted that multiferroic MnTiO3 shows good dielectric and optical properties.