Effects R3+ on the photoluminescent properties of Ca2R8(SiO4)(6)O-2 : A (R = Y, La, Gd; A= Eu3+, Tb3+) phosphor films prepared by the sol-gel process

Using CaCO3, metal oxides (all dissolved by nitric acid) and tetraethoxysilane Si(OC2H5)(4) (TEOS) as the main starting materials, Ca2R8(SiO4)(6)O-2:A (R = Y, La, Gd; A = EU3+, Tb3+) phosphor films have been dip-coated on quartz glass substrates through the sol-gel process. X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM) and photoluminescence (PL) spectra as well as lifetimes were used to characterize the resulting films. The results of XRD indicated that the 1000 degreesC annealed films are isomorphous and crystallize with the silicate oxyapatite structure. AFM and SEM studies revealed that the phosphor films consisted of homogeneous particles ranging from 30 to 90 nm, with an average thickness of 1.30 mum. The Eu3+ and Tb3+ show similar spectral properties independent of R 3, in the films due to their isomorphous crystal structures. However, both the emission intensity and lifetimes of Eu3+ and Tb3+ in Ca2R8(SiO4)(6)O-2 (R = Y, La, Gd) films decrease in the sequence of R = Gd > R = Y > R = La, which have been explained in accordance with the crystal structures.

Electropolymerization of azure B on a screen-printed carbon electrode and its application to the determination of NADH in a flow injection analysis system

The electrooxidation polymerization of azure B on screen-printed carbon electrodes in neutral phosphate buffer was studied. The poly(azure B) modified electrodes exhibited excellent electrocatalysis and stability for dihydronicotinamide adenine dinucleotide (NADH) oxidation in phosphate buffer (pH 6.9), with an overpotential of more than 400 mV lower than that at the bare electrodes. Different techniques, including cyclic voltammetry, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy have been employed to characterize the poly (azure B) film. Furthermore, the modified screen-printed carbon electrodes were found to be promising as an amperometric detector for the flow injection analysis (FIA) of NADH, typically with a dynamic range of 0.5 muM to 100 muM.

Luminescence and energy transfer properties of Ca2Gd8(SiO4)(6)O-2 : A(A = Pb2+, Tm3+) phosphors

Ca2Gd8(SiO4)(6)O-2: A(A = Ph2+, Tm3+) phosphors were prepared through the sol-gel process. X-ray diffraction (XRD), scanning electron microseopy(SEM) and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicate that the phosphors crystallized completely at 1000 degreesC. SEM study reveals that the average grain size is 300 similar to 1000 nm. In Ca2Gd8(SiO4)(6)O-2: Tm3+ phosphors, the Tm3+ shows its characteristic blue emission at 456 nm (D-1(2)-F-3(4)) upon excitation into its H-3(6)-D-1(2)(361 nm), with an optimum doping concentration of 1 mol% of Gd3+ in the host lattices. In Ca2Gd8(SiO4)(6)O-2: Pb2+, Tm3+ phosphors, excitation into the Ph2+ at 266 nm (S-1(0)-P-3(1)) yields the emissions of Gd3+ at 311 nm (P-6-S-8) and Tm3+ at 367 nm (D-1(2)-H-3(6)) and 456 our (D-1(2)-F-3(4)), indicating that energy transfer processes of Pb2+-Gd3+ and Ph2+-Tm3+ have occur-red in the host lattices.

Large-scale synthesis of Berlin green Fe[Fe(CN)(6)] microcubic crystals

Berlin green FeFe(CN)(6) microcubic crystals have been successfully prepared by a simple hydrothermal process between K-3[Fe(CN)(6)] with Na2S2O3 aqueous solution, free of any surfactant or template. The experimental results clearly show that the molar ratio of K-3[Fe(CN)(6)] to Na2S2O3 and their concentrations are the dominant processing factors in controlling the size, morphology, and composition of the resulting products.

Syntheses, structures and near-IR luminescent studies on ternary lanthanide (Er-III, Ho-III, Yb-III, Nd-III) complexes containing 4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)hexane-1,3-dionate

The ligand Hhfth [4,4,5,5,6,6,6-heptafluoro-1-(2-thienyl)hexane-1,3-dione], which contains a heptafluoropropyl group, has been used to synthesize several new ternary lanthanide complexes (Ln = Er, Ho, Yb, Nd) in which the synergistic ligand is 1,10-phenanthroline (phen) or 2,2'-bipyridine (bipy). The two series of complexes are [Ln(hfth)(3)phen] [abbreviated as (Ln)1, where Ln = Er, Ho, Yb] and [Ln(hfth)(3)bipy] [abbreviated as (Ln)2, where Ln = Er, Ho, Yb, Nd]. Members of the two series have been structurally characterized. The growth morphology, diffuse reflectance (DR) spectra, thermogravimetric analyses, and photophysical studies of these complexes are described in detail. After ligand-mediated excitation of the complexes, they all show the characteristic near-infrared (NIR) luminescence of the corresponding Ln(3+) ions (Ln = Er, Ho, Yb, Nd). This is attributed to efficient energy transfer from the ligands to the central Ln(3+) ions, i.e. an antenna effect. The heptafluorinated substituent in the main hfth sensitizer serves to reduce the degree of vibrational quenching. With these NIR-luminescent lanthanide complexes, the luminescent spectral region from 1300 to 1600 nm, which is of particular interest for telecommunication applications, can be covered completely.

Studies of interaction between iron (III) and intermediates of synthetic neuromelanin by means of cyclic voltammetry of Fe(CN)(3-)(6) and dopamine

Neuromelanin is a complex polymer pigment found primarily in the dopaminergic neurons of the human substantia nigra, whose composition is complex including production of dopamine auto-oxidation, glutathione and a variety of amino acid. Neuromelanin forms stable complex with iron (111). We observed that 5,6-dihydroxyindole and its ramification possessed strong ability of chelating iron (111), and they are the production of dopamine auto-oxidation under physiological pH condition. In the present Of L-Cysteine, the relative yields of electrochemical oxidation of dopamine also had strong ability of chelating iron (111). The experimental results suggest that 5,6-dihydroxyindole and 5-S-cysteineldopamine play important roles in the process of synthetic neuromelanin chelating iron (111).

Independence of the brittle-ductile transition from the rubber particle size for impact-modified poly(vinyl chloride)

A series of acrylic impact modifiers (AIMS) with different particle sizes ranging from 55.2 to 927.0 nm were synthesized by seeded emulsion polymerization, and the effect of the particle size on the brittle-ductile transition of impact-modified poly(vinyl chloride) (PVC) was investigated. For each AIM, a series of PVC/AIM blends with compositions of 6, 8, 10, 12, and 15 phr AIM in 100 phr PVC were prepared, and the Izod impact strengths of these blends were tested at 23 degrees C. For AIMs with particle sizes of 55.2, 59.8, 125.2, 243.2, and 341.1 nm, the blends fractured in the brittle mode when the concentration of AIM was lower than 10 phr, whereas the blends showed ductile fracture when the AIM concentration reached 10 phr. It was concluded that the brittle-ductile transition of the PVC/AIM blends was independent of the particle size in the range of 55.2-341.1 nm. When the particle size was greater than 341.1 nm, however, the brittle-ductile transition shifted to a higher AIM concentration with an increase in the particle size. Furthermore, the critical interparticle distance was found not to be the criterion of the brittle-ductile transition for the PVC/AIM blends.

Study on structure and oxide ionic conductivity for new compound Ce(6-x)Ln(x)MoO(15-delta)

A new compound Ce(6-x)Ln(x)MoO(15-delta) has been synthesized by wet-chemistry method. Their crystal structure and oxide ionic conductivity were characterized by powder X-ray diffraction, Raman, IR spectrum and A.C. impedance technique. The XRD results showed that Ce6MO15-delta, Ce(5)LnMoO(15-delta) have cubic symmetry with Fm3m space group. The refined lattice parameters showed that their lattice constants decrease with the decrease of the ionic radius of Ln(3+). The electrochemical measurements showed that the ionic conductivity of resulting oxides Ce(6-x)Ln(x)MoO(15-delta) have an enhance, which may be a kind of promising material for SOFCs.

Properties of compatibilized nylon 6/ABS polymer blends

Nylon 6/poly(acrylonitrile-butadiene-styrene)(ABS) blends were prepared in the molten state by a twin-screw extruder. Maleic anhydride-grafted polypropylene (MAP) and solid epoxy resin (bisphenol type-A) were used as compatibilizers for these blends. The effects of compatibilizer addition to the blends were studied via tensile, torque, impact properties and morphology tests. The results showed that the additions of epoxy and MA copolymer to nylon 6/ABS blends enhanced the compatibility between nylon 6 and ABS, and this lead to improvement of mechanical properties of their blends and in a size decrease of the ABS domains.

七-(2,6-二-O-甲基)-β-环糊精对1,1 -联萘酚对映体手性识别的电喷雾质谱研究

利用电喷雾质谱研究了β-环糊精、七-(2,6-二-O-甲基)-β-环糊精作为手性识别试剂对1,1'-联萘酚对映体的手性识别效应.实验结果表明,在气相中,β-环糊精与七-(2,6-二-O-甲基)-β-环糊精都可以与联萘酚形成非共价复合物.对形成的复合物的串联质谱研究表明,β-环糊精不能识别联萘酚对映体,而七-(2,6-二-O-甲基)-β-环糊精对联萘酚对映体有较强的手性识别效应.进一步研究表明七-(2,6-二-O-甲基)-β-环糊精与联萘酚对映体混合比例以及CID能量对于手性识别并无影响.

Phase transition behavior and structure of the thermotropic liquid crystal 6-{[(4 '-{[(undecyl)carbonyl]oxy}biphenyl-4yl)carbonyl]oxy}-1-hexyne

The phase transition behaviors and corresponding structures of 6-{[(4'-([(undecyl)carbonyl]oxy)biphenyl-4yl)carbonyl]oxyl-l-hexyne (A4EE11) were investigated using differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and wide angle X-ray diffraction (WAXD). In comparison with the published homologues, 5- [(4'-heptoxy-biphenyl-4-yl)carbonyl]oxyl-1-pentyne (A3EO7) which shows a monotropic smectic A (SmA) phase and a metastable monotropic smectic C (SmC) phase; 5-{ [(4'-heptoxybiphenyl-4-yl)oxy]carbonyl)- I-pentyne (A3E'O7) that exhibits three enantiotropic stable liquid crystalline (LC) phases, SmA phase, SmC phase and smectic X (SmX) phase; 5-{[(4'-heptoxy-biphenyl-4-yl)carbonyl]oxy}-1-undecyne (A9EO7) which has a monotropic SmA phase and a metastable crystal phase, A4EE11 integrates the enantiotropy, monotropy and metastability of the LC phases of those three compounds. Upon cooling from isotropic state to room temperature, in the temperature range of 62.0 to 58.5 degrees C, A4EE11 shows an enantiotropic smectic A (SmA) phase with a layer spacing d=32.69 angstrom.

(E)-6-fluoropyridine-2-carbaldehyde oxime

The title compound, C6H5FN2O, exists as the E isomer. The crystal structure is stabilized by O-(HN)-N-... hydrogen bonding.

6,7,8,9-Tetrahydro-5H-pyrido[2,3-b]azepine-5,8-dione: a hydrogen-bonded dimer structure

In the title compound, C9H8N2O2, two crystallographically independent molecules form a dimer structure, in which two N-H center dot center dot center dot N hydrogen bonds generate an intermolecular R-2(2)( 8) ring.