218 resultados para CA2 STORES


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A functionalized fullerene derivative containing a monoaza-18-crown-6 moiety was investigated by facilitated ion (such as Li+, Na+, K+, NH4+, Mg2+, and Ca2+) transfer across the micro-water/nitrobenzene interface supported at the tip of a micropipet. The current responses were detected by cyclic voltammetry and Osteryoung square wave voltammetry, which demonstrated that the facilitated ion transfer does occur by an interfacial complexation-dissociation process. The diffusion coefficient of this compound in nitrobenzene was approximately (5.90 +/- 0.04) x 10(-7) cm(2) s(-1), which is 1 order of magnitude less than other common ionophores due to the large size of the molecule. The selectivity of this molecule toward the metal ions followed the sequence Na+ > Li+ > K+ > NH4+ > Ca2+ similar to Mg2+. In addition, this compound was also easy to form film at the water/nitrobenzene interface to inhibit the simple ion transfer of tetramethylammonium ion. However, the adsorption of this ionophore has less influence on the facilitated metal ion transfer.

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La2CaB10O19Eu3+UV VUV,Eu3+,Eu3+O2-La3+,Eu3+O2-Ca2+,Eu3+(CTB)244nm,130170nmEu3+f d

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( AFM) 1 986 [1,2 ] , , .DNA AFM , DNA , , [3,4 ] . DNA AFM , . ( Mg2 + ,Ba2 + ,Mn2 + Ca2 + [5] ) , , , , , , DNA , DNA . AFM , Ni( phen) 2 + 3 DNA , .11 .1Ni( phen) 2 + 3 Ni2 SO4 ( ) 1 ,1 0 - ( ) .PBR32 2 /pst ...

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(La3 + ,Eu3 + ,Dy3 + ,Yb3 + ) - , - ( )Tb -A2 . <3mol/LA2 , 5 mol/L ;Ca2 + , ; ;Tb - 10 mol/L

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The general and synchronous spectra of phospholipase A(2) (PLA(2)) isolated from Chinese agkistrodon blomhoffii Ussurensis snake venom were studied. The chromophores of PLA(2) were mainly contributed by tyrosine and tryptophane residues when the intervals between the excitation wavelength and the emssion waveleagth (Delta lambda) were 20nm and 75nm, respectively. The pH of buffers could change the fluorescence intensities of PLA(2) by changing the charge distribution of its amino acid chain. Ca2+ can not only increase the emission fluorescence intensity of PLA(2) but also improve the reaction rate of PLA(2) with its corresponding substrate DPPC.

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CaY1-xBO4: xEu was synthesied by solid state reaction method, and the displacement and luminescence of the Eu3+ in CaYBO4 host were studied. Two luminescent centers could be observed at certain Eu3+-concentration, indicating that the Eu3+ occupies two different crystallographic sites. This result shows that the Eu3+ occupies two different Y3+ sites in CaYBO4. The investigation on Eu-O charge transfer bands indicates that the larger distortion or the lower symmetry of Eu3+ site is,the shorter wavelength of the Eu-O charge transfer band is. When the Eu3+-concentration is high (x > 0.10), Eu3+ occupies the sites of Ca2+ and is reduced to Eu2+.

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CaY1 -xBO4xEu ,Eu3+CaYBO4Eu3+ , ,Y ;Eu O ,Eu3+ ,Eu O ;Eu3+ (x >0 1 0 ) ,Eu3+Ca2 + ,Eu3+Eu2 +

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Eu3+-activated calcium silicate (CaO-SiO2:Eu3+) luminescent films were prepared by the sol-gel method. The structural evolution of the film was studied by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), and the luminescence properties of the phosphor films were investigated as a function of heat treatment temperature. The XRD study indicates that a kilchoanite phase forms in the film sintered at 800 degreesC, which is different from that in gel powder treated under the same conditions. The SEM results show that the film thickness decreases and the particles in the film become smaller with increasing heat treatment temperature. The CaO-SiO2:Eu film shows the characteristic emission of Eu3+ under UV excitation, with the Eu3+ D-5(0)-->F-7(2) band (616 nm) being the most prominent. A large difference in the Eu3+ lifetime is observed between the film samples treated at 500 and 700 degreesC (or above). Concentration quenching occurs when the Eu3+ doping concentration is above 6 mol% of Ca2+ in the film.

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.Ca2 +Y3+Sr2 +La3+,Y2 Cu2 O5La2 CuO4 .X (XPS)Y2 -xCaxCu2 O5La2 -xSrxCuO4.

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(Eu3+ ,Tb3+ )Ca2 Y8(SiO4 ) 6 O2 X (XRD) , (IR) , (SEM) ,XRD 70 0 ,80 0Ca2 Y8(SiO4 ) 6 O2 ,10 0 0Ca2 Y8(SiO4 ) 6 O2 Eu3+ ,Eu3+ 5D0 -7F2 (616nm)Ca2 Y8(SiO4 ) 6 O2 Tb3+ ,5D3-7FJ,5D4 -7FJ(J =6,5 ,4,3 ) ,5D4 -7F5(5 44nm)

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Eu2+MMgAl10O17M0.10nm-Al2O3Eu2+Ca2+-Al2O3Mg2+Al3+Eu2+dfEu3+-Al2O3Eu2+-Al2O3Mg2+Al3+Eu2+dfffEu3+-Al2O3Eu2+ffEu3+-Al2O3-Al2O3Eu2+ffdf

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4 5Ca2 +La3+Gd3+H 3 5Ca2 + .La3+Gd3+H 3 5Ca2 + 6 10 .Ca2 +Ca2 + ,H 3 5 2Ca2 + ,Ca2 + ,La3+Gd3+H 3 5 1Ca2 + ,La3+Gd3+Ca2 +KmVmax,Ca2 +Ca2 +.

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Ca2+Tb3+A2(phospholipase A2)Ca2+A2Ca2+ A2DPPCTb3+A2 A2.

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The stability constants of M-L binary system and M-L-L' (M = La3+ similar to Yb3+, Y3+ and Ca2+; L= DL-malic aicd, L' = L-hydroxyproline) ternary system were determined by pH-(0)-tentiometric method under the simulating physiological condition(37 degrees C, I=0.15 mol/L NaCl). The complex species MpLqLr'H-s(abbr as pqrs) in the sytems were ascertained by program COMPLEX. The results show that there are three species(1101, 1100 and 1200) in M-L binary system and one species(1010) in M-L' binary system. In addition to the above four species, a new species, 1112 was found in the M-L-L' ternary system, which is the only species of mixed ligands. Rare earth ions form more stable complexes than calcium ion does and the stability differences between their complexes in the ternary system are less than that in the binary system. The distributions of all the species in La-L-L' ternary system vs pH are discussed.

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A novel kind of K+ sensor with valinomycin-incorporated bilayers supported on a gold electrode consisting of self-assembled alkanethiol monolayers (SAMs) and a lipid monolayer has been fabricated successfully. The lipid monolayer is deposited on the alkylated surface of the first alkanethiol monolayer through three different methods, such as the Langmuir-Blodgett (LB) technique, painted method and painted-frozen method. The response of K + sensors produced by a painted or painted-frozen lipid monolayer on an alkanethiol alkylated gold electrode is larger than that by the LB method, which is due to the difference in fluidity of the three kinds of bilayers. Selectivity coefficients KK+, Na+, KK+, Li+, KK+, Ca2+ and KK+, Mg2+ are 10(-4), 10(-4), 2 x 10(-5) and 3 x 10(-5) respectively, and there is no obvious difference among different fabricating methods. A linear response toward the potassium ion was found in the range from 10(-1) M to 10(-5) M with the detection limit of 10(-6) M. The sensor has a slope of 60 mV per decade. Meanwhile, the longevity of the sensor was improved obviously for at least two months at about -10 degrees C. The higher stability shows the possibility to fabricate a practical biosensor.