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Yanji, China

Yanbian University is one of the key universities of the People's Republic of China, located at Yanji, Yanbian Korean Autonomous Prefecture, Jilin Province. Wikipedia.

Zhou X.,Ewha Womans University | Zhou X.,Yanbian University | Lee S.,Ewha Womans University | Xu Z.,CAS Dalian Institute of Chemical Physics | Yoon J.,Ewha Womans University
Chemical Reviews | Year: 2015

The development of chemosensors has become an important research topic in supramolecular analytical chemistry, and as a result, it has attracted the continuous interest of academic researchers in chemistry and biology. The strategy of using pH indicators was first employed in the construction of fluorescent sensors for CO2. Another strategy was developed based on the chemical reaction between amine and CO2 in which CO2 is a weak electrophile that can react with an active basic amine to form corresponding carbamate salt and ammonium salt. On the basis of this chemical mechanism, a series of fluorescent sensors has been achieved to date. One approach is directly inserting an amine group into the conjugated fluorophore. Sessler and co-workers constructed two colorimetric- and fluorescence-based CO2 sensors based on N-fused compounds. Chang and colleagues developed the fluorescent sensor by using a commercial resorufin for sulfite detection. In this case, sulfite can selectively react with the carbonyl carbon of the levulinate and yield a tetrahedral intermediate. This corresponding intermediate can next undergo an intermolecular cyclization to release the free resorufin moiety, resulting in an up to 57-fold fluorescence enhancement with a detection limit of 49 μM in aqueous solution. Fluorescent sensors for NO containing o-phenylenediamine (OPD) moieties and fluorophores have been developed by Nagano?s group and shown to be highly effective for visualizing this gas in vitro and in vivo. Source

Gu G.-R.,Yanbian University | Ito T.,Osaka University
Applied Surface Science | Year: 2011

Nano-sheet carbon films (NSCFs) coated with very thin (≈5-nm-thick) metal layers were fabricated on Si wafer chips by means of quartz-tube-type microwave-plasma chemical-vapour-deposition method with hydrogen-methane gas mixture and an electron beam evaporation method. Field emission (FE) current densities obtained at a macroscopic average electric field, E, of ≈10 V/μm changed from 13 mA/cm2 for NSCF with no coated metal to 1.7, 0.7 and 30 mA/cm2 for Ti-, Al- and Au-coated NSCFs, respectively, while the threshold E varied from 4.4 V/μm for the former one to 5.3, 5.4 and 2.0 V/μm for the corresponding latter ones, respectively. As the FE currents of Au-coated NSCFs tended to be saturated in a higher E region, compared to those of NSCFs with no coated metal, no simple Fowler-Nordheim (F-N) model is applicable. A modified F-N model considering statistic effects of the FE tip structures and a space-charge-limited-current effect is successfully applied to an explanation for the FE data observed in the low and high E regions. © 2010 Elsevier B.V. All rights reserved. Source

TIAN L.,Yanbian University
Journal of Rare Earths | Year: 2010

The photoluminescence (PL) properties of Ca4YO(BO3)3 doped with Bi3+, Dy3+, and Pr3+ ions were investigated. These compounds were prepared using a typical solid-state reaction. The excitation and emission spectra were measured using a spectrofluorometer. For Ca4YO(BO3)3:Bi3+, the excitation spectrum showed the bands at about 228, 309, and 370 nm which correspond to the 1S0→1P1 transition and the 1S0→3P1 transition of Bi3+ ions. The emission band at 390 nm corresponded to the 3P1→1S0 transition of Bi3+ ions. For Ca4YO(BO3)3: Bi3+,Dy3+, energy transfer occurred from Bi3+ to Dy3+ somewhat. In Ca4YO(BO3)3:Bi3+,Dy3+,Pr3+, the excitation band at 367 nm was enhanced obviously due to the energy migration from Bi3+ to Pr3+, which converted efficiently the emission of semiconductor InGaN based light-emitting diode (LED). Therefore, the emission of Dy3+ ions was enhanced due to the energy migration from the process of Bi3+→Pr3+→Dy3+. It resulted in the good color rendering. © 2010 The Chinese Society of Rare Earths. Source

Zheng N.,Yanbian University | Jin Y.,Yanbian University
Journal of Magnetism and Magnetic Materials | Year: 2012

Half-metals, which show 100% spin polarization at the Fermi level, have potential applications in spintronics. We investigated the half-metallicity of full-Heusler Ti 2YAl (Y=V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) alloys with an Hg 2CuTi-type structure by means of the all-electron full-potential linearized augmented plane-wave method within the generalized gradient approximation. The Ti 2MnAl alloy is found to be a half-metallic antiferromagnet, and the Ti 2YAl (Y=Fe, Co, and Ni) alloys are half-metallic ferrimagnets, whereas the Ti 2YAl (Y=V, Cr, Cu, and Zn) alloys are conventional ferromagnets. Total magnetic moments (M t) of the Ti 2YAl (Y=Mn, Fe, Co, and Ni) alloys are calculated to be integers and linearly scaled with the total number of valence electrons (Z t) by Mt= Zt-18. Band-gaps are demonstrated to be mainly determined by the bonding t 2 and antibonding t2 states created from the hybridizations of the d states between the Ti(A)-Ti(B) coupling and Y (Y=Mn, Fe, Co, and Ni) atom. © 2012 Elsevier B.V. All rights reserved. Source

New silicon source (3-glycidyloxypropyltrimethoxysilane (GPTMS)) was used to make non-glass inorganic-organic hybrid membranes with diethylethylammonium trifluoromethanesulfonate ([dema][TfO]) by the sol-gel method. The hybrid membranes were studied with respect to their structural, thermal, proton conductivity and pores properties. The Fourier transform infrared spectroscopy (FT-IR) results showed that there was intermolecular interaction between ionic liquid and Si-O-Si skeleton structure in the inorganic-organic hybrid membranes. The thermogravimetric (TG) and differential scanning calorimetry (DSC) analysis showed that the hybrid membranes displayed good chemical stability and were thermally stable up to more than 200°C in air. The N2 adsorption test showed the hybrid membranes had good pore property and ionic liquid influenced the structure of hybrid membrane. Proton conductivity was measured from 20°C to 220°C and high conductivity of 1.2×10-2S/cm was obtained for a 60wt% [dema][TfO] doped hybrid membrane (ionogel) at 220°C under anhydrous conditions. This method for the preparation of hybrid membranes is promising and may be used for the proton exchange membrane in fuel cells. © 2013 Elsevier B.V. Source

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