72 resultados para 16:1(n-7) 16:1(n-5) 20:5(n-3)
Resumo:
Lanthanide-doped sol-gel-derived materials are an attractive type of luminescent materials that can be processed at ambient temperatures. However, the solubility of the lanthanide complexes in the matrix is a problem and it is difficult to obtain a uniform distribution of the complexes. Fortunately, these problems can be solved by covalently linking the lanthanide complex to the sol-gel-derived matrix. In this study, luminescent Eu3+ and Tb3+ bipyridine complexes were immobilized on sol-gel-derived silica. FT-IR, DTA-TG and luminescence spectra, as well as luminescence decay analysis, were used to characterize the obtained hybrid materials. The organic groups from the bipyridine-Si moiety were mostly destroyed between 220 and 600 degreesC. The luminescence properties of lanthanide bipyridine complexes anchored to the backbone of the silica network and the corresponding pure complexes were comparatively investigated, which indicates that the lanthanide bipyridine complex was formed during the hydrolysis and co-condensation of TEOS and modified bipyridine. Excitation at the ligand absorption wavelength (336 nm for the hybrid materials and 350 nm for the pure complexes) resulted in strong emission of the lanthanide ions: Eu3+ D-5(0)-F-7(J) (J = 0, 1, 2, 3, 4) and Tb3+ D-5(4)-F-7(J) (J = 6, 5, 4, 3) emission lines due to efficient energy transfer from the ligands to the lanthanide ions.
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Organically modified silica xerogels (OMSX) and Eu3+ (Tb3+)-doped OMSX were prepared by the reaction of (3-aminopropyl) triethoxysilane (APS) with 3-isocyanatepropyltriethoxysilane (ICPTES) followed by the subsequent hydrolysis and condensation in the presence of Eu3+ (Tb3+) via sol-gel method, which were characterized by FT-IR, XRD, fluorescence excitation and emission spectra. The as-formed OMSX shows a strong blue emission with the maximum excitation and emission wavelength at 351 and 420 nm, respectively. Due to the spectral overlap between the emission band of OMSX and f-f absorption lines of Eu3+ and Tb3+ in the UV-blue region, an energy transfer was observed from OMSX host to Eu3+ and Tb3+ in OMSX/Eu3+ and OMSX/Tb3+, respectively. Excitation at 350-360 nm resulted in a very weak emission around 420 nm from OMSX host and strong emission of Eu3+ and Tb3+ in OMSX/Eu3+ and OMSX/Tb3+, respectively. The emission spectra of Eu3+ and Tb3+ consist of D-5(0)-F-7(J) (J = 0, 1, 2, 3, 4) and D-5(4)-F-7(J) (J = 6, 5, 4, 3), respectively. Furthermore, the predicted structure of OMSX/Eu3+ and OMSX/Tb3+ is presented.
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Novel hybrid thin films covalently doped with Eu3+ (Tb3+) have been prepared via direct routes involving co-condensation of tetraethoxysilane and phen-Si in the presence of Eu3+ (Tb3+) by spin-casting and their luminescence properties have been investigated in detail. Lanthanide ions can be sensitized by anchored phenanthroline in hybrid thin films. Excitation at the ligand absorption wavelength (272 nm) resulted in the strong emission of the lanthanide ions i.e. Eu3+ D-5(0)-F-7(J) (J=0, 1, 2, 3, 4) emission lines and Tb3+ D-5(4)-F-7(J) (J = 6, 5, 4, 3) due to the energy transfer from the ligands to the lanthanide ions.
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A new polymer-supported metallocene catalyst has been prepared, The polymer-supported metallocene displayed considerably high activity in ethylene polymerization, the highest being 3.62x10(7) gPE/molZr.h, the molecular weight of the polyethylene produced was Mn = 1.29x10(5). about 3-4 times those of corresponding homogeneous zirconocenes. The polymer-supported metallocene keeps the characteristics of homogeneous metallocene catalysts, and offers some features, such as adaptable to gas phase and slurry processes: easy to prepare in low cost: relatively high activity and lower MAO/Zr ratio; lower inorganic residues in the polyolefins as compared to cases of SiO2, Al2O3 or MgCl2; unitary active structure, no complex surface as with SiO2; good control of morphology of the resulting polymer.
Resumo:
PVC,19mV/pCs_m~(3+),1.010~(-4)1.010~(-2)moldm~(-3),,,PVC,,1.010~(-7)1.010~(-5)moldm~(-3),20mV/pCs_m~(3+)
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The reaction between LaCl_3 and LiCl in THF at room temperature, with hexane as precipitant and glycol dimethyl ether as complexing agent, has been studied. A complex with the composition of (LaCl)DME(_2-Cl)_5(_3-Cl)(LaDME)Li(THF)_2 has been synthesized, its structure was studied by single crystal X-ray diffraction technique. The diffraction intensities were collected at about 100. The complex belongs to the triclinic space group P1 with =11.123(3), 6=16.564(5), c=8.653(3)A, =95.16(3), =...
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In the title compound, [Cu(NCS)(2)(C5H6N2)(2)], each Cu atom is coordinated by two N atoms from two Eim (Eim = 1-vinyl-1H-imidazole) ligands and two N atoms from two isothiocyanate groups. The Cu atom adopts a square-planar geometry. The mean Cu-N(Eim) and Cu-N(NCS) distances are 1.960 (6) and 1.993 (6) angstrom, respectively.
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, 5 km 7 km 24 h, 7 d14 d 21 d 28 d , 1 d 5 km 3 d 7 d,; 14 d21 d 28 d, ,
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RNAO1igo(dT)mRNAmRNAOligo(dT)cDNAgtll(titer)7105pfu90cDNAPCRcONAPG cDNApBluescriptGriesonPGcDNAPG3'PCRcONA11PCRgtlipBlusoript1.0kb5800bp3'I3AAPCRPCRPCR1.5kbpBl121pBin437RNA
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(Gymnocyprisselincuoensis)vonBertalanffyGompertz ,Gompertz 12 ,vonBertalanffy 18vonBertalanffy :Lt
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A compact polarization-insensitive 8x8 arrayed waveguide grating with 100GHz channel spacing at 1.55 mu m is presented on the material of silicon on insulator (SOI). Increasing the epitaxial layer thickness can reduce the birefringence of the waveguide, but the wvaeguide's bend radius also increases at the same time. We choose the SOI wafer with 3.0 mu m epitaxial layer to reduce the device's size and designed the appropriate structure of rib wave-guides to eliminate the polarization dependant wavelength shift. Compared to the other methods of eliminating the polarization dependant wavelength shift, the method is convenient and easy to control the polarization without additional etching process. The index differences between TE0 and TM0 of straight and bend waveguides are 1.4x10(-5) and 3.9x10(-5), respectively. The results showed that the polarization dependant wavelength shift is 0.1nm, and the device size is 1.5x1.0 cm(2).
Resumo:
A bisfurylfulgide, E, E-3,4-bis[1-(2,5-dimethyl-3-furyl)ethylidene]-3,4-dihydrofuran-2,5-dione, is synthesized by Stobbe condensation reaction. The molecular structure of target compound is confirmed by single crystal X-ray crystallography analysis. It shows that the distances between two possible reaction sites of molecule are 0.3394 and 0.3406 nm respectively, which is favorable to photocyclization. The photochromic properties of this compound in different solvents are investigated, and the result shows that the compound exhibits excellent photochromic behavior. The primary result of applied research on parallel image storage is also presented.
Resumo:
Tb~(3+)Pr~(3+)Ce~(3+)Tb~(3+)TbTbTb~(3+)Pr~(3+)Tb1 Ce~(3+)d HZO_3HClO_4 254nm)(366nm)(351/364nm, 458 nm, 477nm, 502 nm, 514, nm)Ce~(3+)-HZO_3-HClO_4Ce~(3+)Ce(ZO_3)_4 254 nmCe~(3+)Ce~(3+)2 Tb~(3+)KIO_4-KOH 366nm)Tb~(3+)-KIO_4-KOHTb~(3+)Tb~(3+)Tb~(4+)Tb(IV)/Rb(III)KOH0.3MKIO_4Tb~(3+)KOH=0.6M, KIO_4=0.22M, 13 E_(Tb(IV)/Tb(III))=0.68Tb~(4+)420nm3 Tb Tb~(3+)KIO_4-KOHTb366nmTb~(3+)Tb~(4+)420nmTb1*10~(-5)M - 1*10~(-3)MBeerTb0.2%Tb4 Tb Tb~(3+)KIO_4-KOH-K_2S_2O_8TbTb~(3+)-KzO_4-KOH-K_2S_2O_8Tb~(3+)Tb~(4+)420nmCe~(3+)KIO4KOHCe~(4+), Ce~(4+)420nmTb5*10~(-5)-5*10~(-4)MBeerTb1Tb5 Pr~(3+)KZO_4KOHPr~(3+)-KZO_4-KOHPr~(3+)Pr~(4+)400nmPr~(4+)400nmPr~(3+)KOHKZO4Ce~(4+)Pr~9(4+)KOHKZO4Pr~(4+)Ce~(4+)Pr~(3+)
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AuriporiaOligoporusPostia50% 125223Postia calcarea P. gloeocystidiataP. subundosa2Postia lateritiaP. persinica 2 3 42793%29188
