Isopiestic Determination of Water Activity on the System LiNO<Subscript>3</Subscript>+KNO<Subscript>3</Subscript>+H<Subscript>2</Subscript>O at 273.1 and 298.1 K

Water activities in the ternary LiNO₃+KNO₃+H₂O system and its sub-binary systems have been measured by the isopiestic method at 273.1 and 298.1 K. The measured results were treated by a Pitzer-Simonson-Clegg thermodynamic model, from which the predicted solubility isotherms were compared with the experimental results. Based on this comparison, the reliability of the measured results was discussed. The measured results help in predicting the phase diagram of the ternary system, as well as other multi-component systems based on the ternary system.     

罗丹明类测定三聚氰胺的荧光探针的合成及应用研究

报道了罗丹明乙二醛酰腙的合成及与三聚氰胺的反应。在pH 3.0的缓冲溶液中三聚氰胺对罗丹明乙二醛酰腙的荧光强度有增强作用,其增强程度与三聚氰胺的浓度成正比,据此建立了一种新的测定三聚氰胺含量的荧光分析法。该方法线性范围为0.5~10.0 mg/L,r=0.994,检出限为0.15 mg/L,样品测定的RSD为1.7%(n=7)。     

A 4-Methylumbelliferone-based Fluorescent Probe for Sodium New Houttuyfonate

A new fluorogenic probe for sodium new houttuyfonate (SNH) was proposed. 4‐Methylumbelliferyl‐2,4‐dinitrobenzenesulfonate (4‐MUDNBS) was a nonfluorescent compound and was synthesized via the one‐step reaction of 4‐methylumbelliferone (4‐MU) with 2,4‐dinitrobenzenesulfonyl chloride. In basic media, SNH was decomposed to produce sodium sulfite, which then reacted with 4‐MUDNBS to yield highly fluorescent 4‐MU, hence leading to the fluorescence increase of the reaction solution. A linear correlation existed between the emission intensity and the concentration of SNH within the range from 0.5 to 15 μg·mL⁻¹ with a detection limit of 0.15 μg· mL⁻¹ (3δ). The effect of substituents on the benzenesulfonyl moiety of the probe is discussed, and the presence of electronegative groups is favorable for the proposed cleavage reaction.     

Delayed Fluorescent Emission from Pyrene Doped Phenanthrene Nanoparticles Based on Triplet-triplet Energy Transfer

Doped nanoparticles were prepared from pyrene and phenanthrene using a facile reprecipitation method. The doped nanoparticles presented unique delayed fluorescent emissions of pyrene under the unprotected condition. The ratio of the intensity of delayed fluorescence (I_DF) to that of phosphorescence (I_P) is about 4:1, which almost keeps unchanged with the decrease of pyrene content at room temperature. The intensity of the delayed fluorescence emissions is dependent on the relative content of pyrene, as well as the aggregation degree of nanoparticles. The delayed emissions are contributed to efficient triplet‐triplet energy transfer from phenanthrene (donor) to pyrene (acceptor). Steady fluorescence measurement have proved that the singlet‐singlet energy transfer process was also existent dominated by the radiation energy transfer mechanism.     

Studies on mono- and dinuclear bisoxime copper complexes with different coordination geometries

Two new mono- and dinuclear Cu(II) complexes, namely [CuL¹]·0.5H₂O (1) and [(Cu₂(L²)₂)(DMF)]·0.5DMF (2) (H₂L¹ = 1,2-bis{[(Z)-(3-methyl-5-oxo-1-phenyl-1H-pyrazolidin-4(4H)-yl)(phenyl)]methylene-aminooxy}ethane; H₂L² = 1,3-bis{[(Z)-(3-methyl-5-oxo-1-phenyl-1H-pyrazolidin-4(4H)-yl)(phenyl)] methyleneaminooxy}propane), have been synthesized and characterized by X-ray crystallography. The unit cell of complex 1 contains two crystallographically independent but chemically identical [CuL¹] molecules and one crystalline water molecule, showing a slightly distorted square-planar coordination geometry and forming a wave-like pattern running along the a-axis via hydrogen bonding and π···π stacking interactions. Complex 2 has a dinuclear structure, comprising two Cu(II) atoms, two completely deprotonated phenolate bisoxime (L²)²⁻ moieties (in the form of enol), and both coordinated and hemi-crystalline DMF molecules. Complex 2 has square-planar and square-pyramidal geometries around the two copper centers, whose basic coordination planes are almost perpendicular and form an infinite three-dimensional supramolecular network structure involving intermolecular C–H···N, C–H···O, and C–H···π(Ph) hydrogen bonding and π···π stacking interactions of neighboring pyrazole rings.     

Determinations of Intermediate Neutral Species in Hydrocarbon Discharge Plasma

This work reports laser ionization combined with Time-Of-Flight (TOF) mass spectrometry investigation on intermediate species in the hydrocarbon plasma of atmospheric-pressure fast-flow pulsed dc-discharge. All neutral intermediate species including transient radicals from benzene/Ar discharge have been characterized by a molecular beam sampling combined with TOF mass spectrometry. This shows that with a hydrocarbon gas mixture of 0.3% C₆H₆ in Ar discharge the intermediate species consist of simple radicals (such as C₂, C₅H₅, C₇H₇) and polycyclic organic molecules (C₁₀H₈, C₁₃H₁₀, C₁₄H₁₀). Theoretical studies on total energies and ionization potentials of the intermediate species have been carried out using the hybrid density functional theory. Effect of the ionization potential on mass spectral intensity has been discussed. Based on the observed data, the possible major neutral reaction channels of the plasma chemistry have been discussed. The developed experimental method has implications in volatile organic compounds removing and impurities diagnosis in Tokamak edge-plasma.     

EFFECT OF GAS FLOW RATE ON CRYSTAL STRUCTURES OF ELECTROSPUN AND GAS-JET/ELECTROSPUN POLY(VINYLIDENE FLUORIDE) FIBERS

The effect of gas flow rate on crystal structures of electrospun and gas-jet/electrospun poly(vinylidene fluoride) (PVDF) fibers was investigated.PVDF fibers were prepared by electrospinning and gas-jet/electrospinning of its N,N-dimethylformamide (DMF) solutions.The morphology of the PVDF fibers was investigated by scanning electron microscopy (SEM).With an increase of the gas flow rate,the average diameters of PVDF fibers were decreased.The crystal structures and thermal properties of the PVDF fibers w...     

Planar or quasi-planar octa- and ennea-coordinate aluminum and gallium in boron rings

An ab initio theoretical investigation has been performed on planar or quasi-planar octa-and ennea-coordinate Al and Ga centered in X@B8- and X@B9 (X=Al, Ga). These high symmetry molecular wheels all turned out to be true minima of the systems and σ+π double aromatic in nature, similar to the previously characterized D8h B@B8- both electronically and geometrically. Adiabatic and vertical detachment energies of the anions and the ionization potentials of the neutrals have been calculated to aid their eventua...     

Phase composition and phase transformation in Bi(Sb,Nb,Ta)O4 system

In this work Bi(Sb_xNb_yTa_z)O₄ (x + y + z = 1) samples are prepared using mixed-oxide method. A pseudo-ternary phase diagram of Bi(Sb,Nb,Ta)O₄ system is given below the melting point. It is composed of a monoclinic phase region, an orthorhombic phase region and a monoclinic–orthorhombic co-existing phase region. In the orthorhombic phase region, the transformation from orthorhombic to triclinic phase is found to be sensitive to the composition and sintering temperature. Both the transformation from monoclinic to orthorhombic structure and the transformation from orthorhombic to triclinic structure have been studied by the cell parameters.