Luminescent properties of Mn2+ in hexagonal aluminates under ultraviolet and vacuum ultraviolet excitation

Mn2+-doped xBaO center dot 6Al(2)O(3) and BaMgAl10O17 phosphors were prepared by solid-state reaction. The investigation of vacuum ultraviolet (VUV) excitation spectra of these phosphors exhibits that 0.82BaO center dot 6Al(2)O(3):Mn2+ and BaMgAl10O17:Mn2+ have a stronger absorption than BaO center dot 6Al(2)O(3):Mn2+ at about 147 nm. The emission spectra under VUV excitation demonstrated that 0.82BaOBa center dot 6Al(2)O(3):Mn2+ and BaMgAl10O17:Mn2+ have a higher luminescent intensity than BaO center dot 6Al(2)O(3):Mn2+. The lifetime analysis indicates that they have similar decay times, indicating that 0.82BaOBa center dot 6Al(2)O(3):Mn2+ and BaMgAl10O17:Mn2+ can be used as luminescent materials for plasma display panels. We observed that the critical concentration of the Mn2+ ions by host excitation is different from that of Mn2+ direct excitation, revealing a different mechanism of energy transfer. The critical distance was calculated. A model was suggested to explain the process of the energy transfer from the host to the Mn2+ ions.

Physical and spectral characterization of the human cyclin A gene and its interactions with anthracycline anticancer drugs

Over expression of cyclin A in human tumors has been linked to cancer by various experimental lines of evidence. However, physical and spectral characterization of the human cyclin A gene and its interactions with anticancer drugs have not been reported. Our gene sequence analysis, singular value decomposition method and melting studies in the presence of antitumor agents, daunomycin, doxorubicin and Hoechst 33258 showed that cyclin A gene had both AT-rich and GC-rich domains. For a ligand with unknown DNA binding specificity, this gene sequence can be used to differentiate its DNA binding preference.

Study of carbon-supported Au catalyst as the cathodic catalyst in a direct formic acid fuel cell prepared using a polyvinyl alcohol protection method

In this paper, it is reported for the first time that a carbon-supported Au (Au/C) catalyst for the cathodic catalyst in a direct formic acid fuel cell (DFAFC) was prepared using a polyvinyl alcohol (PVA) protection method. The results indicated that for oxygen reduction, the electrocatalytic activity of the Au/C catalyst prepared with the PVA protection method is much better than that of a Au/C catalyst prepared with the pre-precipitation method. This is due to the small average size and low relative crystallinity of the An particles in the Au/C catalyst prepared by the PVA protection method, compared to that of the Au/C catalyst prepared by the pre-precipitation method, illustrating that the average size and the relative crystallinity of the ALL particles has an effect on the electrocatalytic activity of the Au/C catalyst for oxygen reduction. In addition, because An has no electrocatalytic activity for the oxidation of formic acid, the Au/C catalyst possesses a high formic acid tolerance. After the electrocatalytic activity of the Au/C catalyst for the oxygen reduction is improved, it is suitable to be used as the cathodic catalyst in DFAFC.

Loosely packed self-assembled monolayer of N-hexadecyl-3,6-di(p-mercaptophenylacetylene)carbazole on gold and its application in biomimetic membrane research

Dithiols of N-hexadecyl-3,6-di(p-mercaptophenylacetylene)carbazole (HDMC) have been synthesized and employed to form self-assembled monolayers (SAMs) on gold. One characteristic of the HDMC molecule is its peculiar molecular structure consisting of a large and rigid headgroup and a small and flexible alkyl-chain tail. HDMC adsorbates can attach to gold substrates by a strong Au-S bond with weak van der Waals interactions between the alkyl-chain tails, leading to a loosely packed hydrophobic SAM. In this way we can couple hybrid bilayer membranes (HBMs) to gold surfaces with more likeness to a cell bilayer than the conventional HBMs based on densely packed long-chain alkanethiol SAMs. The insulating properties and stability of the HDMC monolayer as well as the HDMC/lipid bilayer on gold have been investigated by electrochemical techniques including cyclic voltammetry and impedance spectroscopy. To test whether the quality of the bilayer is sufficiently high for biomimetic research, we incorporated the pore-forming protein a-hemolysin) and the horseradish peroxidase into the bilayers, respectively.

A carbon-supported Pd-P catalyst as the anodic catalyst in a direct formic acid fuel cell

In this paper, it is reported for the first time that a carbon-supported Pd-P (Pd-P/C) catalyst for the anodic catalyst in the direct formic acid fuel cell (DFAFC) can be prepared. The Pd-P/C catalyst shows that its electrocatalytic activity and especially its stability for the oxidation of formic acid are much higher than that of a Pd/C catalyst. Therefore, the Pd-P/C catalyst may have practical applications in DFAFCs.

Mercaptoethane sulfonate protected, water-soluble gold and silver nanoparticles: Syntheses, characterization and their building, multilayer films with polyaniline via ion-dipole interactions

Mercaptoethane sulfonate protected, water-soluble gold and silver nanoparticles (Au-MES and Ag-MES) are synthesized by one-phase method and characterized by TEM, TGA and XPS techniques, UV-vis and FTIR spectra. Both Au-MES and Ag-MES nanoparticles are soluble in the water up to 2.0 mg/ml and the stability of AU-MES is much better than that of Ag-MES. When dissolved in the water. they behave like a polyanion and can be used to build multilayer films with polyaniline (PANI) by way of layer-by-layer. A new approach is presented to fabricate the Multilayer films of Au-MES/PANI and Ag-MES/PAN]. The assembly mechanism of these multilayer films is also discussed. We anticipate highly conducting PANI films can be obtained by doping with these nanoparticles.

Transition from crazing to shear deformation in ABS/PVC blends

ABS/PVC blends were prepared over a range of compositions by mixing PVC, SAN, and PB-g-SAN. All samples were designed to have a constant rubber level of 12 wt % and the ratio of total-SAN to PVC in the matrix of the blends varied from 70.5/17.5 to 18/80. Transmission electron microscope and scanning electron microscope have been used to study deformation mechanisms in the ABS/PVC blends. Several different types of microscopic deformation mechanisms, depending on the composition of blends, were observed for the ABS/PVC blends. When the blend is a SAN-rich system, the main deformation mechanisms were crazing of the matrix. When the blend is a PVC-rich system, crazing could no longer be detected, while shear yielding of the matrix and cavitation of the rubber particles were the main mechanisms of deformation. When the composition of blend is in the intermediate state, both crazing and shear yielding of matrix were observed. This suggests that there is a transition of deformation mechanism in ABS/PVC blends with the change in composition, which is from crazing to shear deformation.

Synthesis and structures of the complexes of beta-alkoxycarbonylethyltin trichlorides with N-aryl-2-hydroxyacetophenylideneimines

Sixteen novel beta-alkoxycarbonylethyltin trichlorides and the corresponding N-aryl-2-hydroxyacetophenylideneimines complexes have been synthesized and characterized. An X-ray crystal structure analysis of the complex of beta-methyloxycarbonylethyltin trichloride and N-4-methylphenyl-2-hydroxyacetophenylideneimine has been performed, The crystal belongs to space group , The cell parameters are: a = 1.0201(6) nm, b = 1.082 2(4) nm, c = 1.394 9(6) nm, alpha = 99.88(3)degrees, beta = 98.63(4)degrees, gamma = 97.86(4)degrees, Z = 2, The ligands coordinate to tin atom via phenolic oxygen atom. Coordination of carbonyl oxygen atom to tin atom still exists in the complexes, The coordination number of tin atom is 6.

Synthesis and structure of 1:1 complex of ethylphenyltin dichloride with N-4-methoxyphenyl-2-hydroxynaphthylideneimine

A novel organotin complex, EtPhSnCl(2) . 2HOC(10)H(6)CH = NC6H1OCH3 was synthesized, and its crystal structure was determined by X-ray diffraction method. The crystal is triclinic, belonging to space group, with unit cell parameters a = 1.150 8(5) nm, b = 1. 153 1(5) gm, c = 1. 004 6 (3) nm, alpha = 94. 15 (3)degrees, beta = 115.47 (3)degrees, r = 85. 94 (4)degrees, V = 1199 7(1) nm(3), Z=2, D-c=1.68 g/cm(3), mu=13. 20 cm(-1), F(000)=618 for 4 131 reflections tions. R=0. 047, R(w)=0. 047. The ligand coordinates to tin atom via phenolic oxygen atom. The complex has a distored trigonal bipyramidal structure, the phenolic oxygen atom of the ligand and one of two chlorine atoms occupy the axial position. The distance between noncoodinated nitrogen atom with phenolic oxygen atom is 0. 257 4 nm, which indicates that the intramolecular hydrogen bond of Schiff base ligand is retained in the complex.

ELECTRICAL CHARACTERIZATION INDUCED IN PERNIGRANILINE BY POTASSIUM-ION IMPLANTATION

The electrical conductivities of pernigraniline after ion implantation with potassium ions were studied experimentally. Pernigraniline films were irradiated with doses ranging from 1 x 10(13) to 1 x 10(17) K+ ions/cm2 at 40 keV. The electrical conductivit

硼酸盐玻璃中Gd~(3+)、Dy~(3+)、Bi~(3+)对Tb~(3+)发光性质的影响

本文研究了单掺和双掺(Tb~(3+)、Tb~(3+)+Gd~(3+)、Tb~(3+)+Dy~(3+)、Tb~(3+)+Bi~(3+)约四十余种不同成份的硼酸盐玻璃。探讨了玻璃成份对Tb~(3+)发光性质的影响和Gd~(3+)、Dy~(3+)、Bj~(3+)对Tb~(3+)的胜化作用。在B_2O_2-BaO-M_mO_n(M_mO_n=Li_2O、Na_2O、K_2O、MgO、CaO、SrO、Al_2O_3、La_2O_3和Bi_2O_3)玻璃体系中,当M_mO_n分别为MgO和Al_2O_3时,Tb~(3+)的发光强度最强;M_mO-n为Bi_2O_3时,Tb~(3+)的发光强度最弱。Tb~(3+)的特征发射峰分别随着碱金属、碱土金属和三价金属的离子半径增加而红移。Gd~(3+)、Dy~(3+)、Bi~(3+)对Tb~(3+)均有敏化作用。特别是Gd~(3+),使Tb~(3+)的发光强度增加1～3.8倍,其最佳敏化浓度,因基质玻璃成份而异。

Sm~(3+)在硼酸盐玻璃中的发光及Bi~(3+)对Sm~(3+)的敏化作用

早在六十年代,人们为了寻找较好的激光玻璃,曾对Sm~(3+)离子掺杂的玻璃中的光谱进行过研究。为了探寻新型的激光,发光玻璃,又进一步研究了Sm~(3+)在玻璃中的发光和敏化。我们以寻找一种高亮度,低成本的发光玻璃为目的,研究了基质玻璃组成,敏化离子及其浓度对Sm~(3+)发光性质的影响。 选择B_2O_3-BaO-M_mO_n(M_mO_n=Li_2O,Na_2O,K_2O,MgO,CaO,SrO)玻璃体系,所用原料的纯度皆为分析纯以上,用陶瓷坩埚在1250℃掺杂氧化钐(纯度均大于99％),玻璃的荧光谱和激发光谱,用MPF-4型荧光分光光度计测定。