992 resultados para Sr^2
Resumo:
The SR-protein kinase activity was analyzed and the cytological changes were observed during oocyte maturation in bisexual transparent color crucian carp ( Carassius auratus color variety). The results revealed that the SR-protein kinase activity was sensitive to the artificially induced spawning hormones, and the change of oscillatory activity was similar to that of the maturation-promoting factor (MPF) kinase that regulates meiotic cell cycle in fish.
Resumo:
The luminescence from Eu2+ ions in MF2 (M = Ca, Sr, Ba) fluorides has been investigated under the pressure range of 0-8 GPa. The emission band originating from the 4f(6)5d(1) -> 4f(7) transition of Eu2+ ions in CaF2 and SrF2 shows the red-shift as increasing pressure with pressure coefficients of -17 meV/GPa for CaF2 and -18 meV/GPa for SrF2. At atmospheric pressure, the emission spectrum of BaF2:Eu2+ comprises two peaks at 2.20 and 2.75 eV from the impurity trapped exciton (ITE) and the self-trapped exciton (STE), respectively. As the pressure is increased, both emission peaks shift to higher energies, and the shifting rate is slowed by the phase transition from the cubic to orthorhombic phase at 4 GPa. Due to the phase transition at 4-5 GPa pressure, the ITE emission disappears gradually, and the STE emission is gradually replaced by the 4f(6)5d(1) -> 4f(7) transition of Eu2+. Above 5 GPa, the pressure behavior of the 4f(6)5d(1) -> 4f(7) transition of EU2+ in BaF2: EU2+ is the same as the normal emission of Eu2+ in CaF2 and SrF2 phosphors.
Resumo:
3m~(2+)4f~6f-fd-fd-f4f~nf-f4f~nf-f3m~(2+)3m~(2+)3m~(2+)xBaMgF_4:3m~(2+)3m~(2+)ff3m~(2+)ff~5Do~7F_13m~(2+)ff~5Do~7FoKMgF_3:3m~(2+)3m~(2+)ff3m~(2+)3m~(2+)ffNaMgF_4:3m~(2+)3m~(2+)ffNaMgF_3:3m~(2+)3m~(2+)~5Do~7F_3~5Do~7F_43m~(2+)3m~(2+)3mFd-fffS3m~(2+)3m~(2+)d-fKxNo_1-xMgF_3:3m~(2+)KMgF_3-xClx:3m~(2+)KMgF_(2.9)*0.1:3m~(2+) (X=FClBrI)3m~(2+)ff3m~(2+)3m~(2+)ff3m~(2+)ff3m~(2+)ffBaCl_2:3m~(2+)3m~(2+)3m~(2+)0.02mol3m~(2+)3mF_3KMgF_3:3m~(2+)3m(III)3m(II)3mF_33m(III)3m(II)S3m~(2+)3m~(2+)3m~(2+) KMgF_3NaMgF_3BaClFBaBrF3m~(2+)MLnFs(M=Ca Sr Ba Ln=La Crd)3m(III)3m(II)3m
Resumo:
R_1Ba_2Cu_3O_(2-x) (R = LaNdSmEuGdDrHoErTmYb)Y_2Ba_2Cu_3O_(2-x) (x = 0.101.17)Y_1Ba_2Cu_3O_(7-x)S_x (x = 02)R_1Ba_2Cu_3O_(2-x)T > TcCuric-WeissY_1Ba_2Cu_3O_(2-x)Cu~(2+)Cu~(2+)R~(3+)CT > 700K)Curic-WeissCu~(2+)R_1Ba_2Cu_3O_(2-x)T < TcCuric-WeissR~(3+)SrR_1Ba_2Cu_3O_(2-x)BaSm~(3+)Curic-WeissSm_1Ba_2Cu_3O_(2-x)Sm~(3+)Van VlccKY_1Ba_2Cu_3O_(2-x)6.906.49(7-x) = 5.83123Curic-Weiss(7-x) = 6.90PauliPeffCu(2)dPeffCu(1)Cu~(2+)EPRY_1Ba_2Cu_3O_(2-x)EPRCu~(2+)(d~9, S = 1/2, I = 3/2)EPREPRCu(1)EPRCu(1)~(2+)Y_1Ba_2Cu_3O_(2-x)EPRY_2Cu_2O_5BaCuO_2Y_2BaCuO_5EPR1spin/cu(7-x) = 6.496.40Y_1Ba_2Cu_3O_2gY_1Ba_2Cu_3O_(2-x)Sxx = 0.11Tc = 92.6KY_1Ba_2Cu_3O_(7-x)2KTc0x = 0.040.060.111.20Curic-Weissx = 0.871.2230K240KCu1x = 0.11 (Tc = 92.6K)EPRCu~(2+)CuCu~(1+)-s-EPRCu(+1+2)
Resumo:
MF_2:Eu~(2+)(M = MgCaSrBa); AlF_3:Eu~(2+); Ax:Eu~(2+) (A = Nak; x = Cl. Br); A_2BeF_4:Eu~(2+) (A = Nak); ABF_4:Eu~(2+)A_2SiF_6:Eu~(2+) (A = NakRbCs); NasAl_3F_(14):Eu~(2+)Na_3AlF_6:Eu~(2+)K_2MgF_4:Eu~(2+); Al_2O_3:Eu~(2+)BeAl_2O_4:Eu~(2+)AlF_3:Eu~(2+) Al_2O_3:Eu~(2+)BeAl_2O_4:Eu~(2+)Eu~(2+)ffEu~(2+)ffNaBF_4A:Eu~(2+)Na_2SiFe_6:Eu~(2+)Na_2BeF_4:Eu~(2+)K_2BeF_4:Eu~(2+)Na_5Al_3F_(14):Eu~(2+)Eu~(2+)ffBlasseFouassier Eu~(2+)Eu~(2+)Eu~(2+)Eu~(2+)Eu~(2+)Eu~(2+)EuLLEu~(2+)Eu~(2+)EuSanderson Eu MF_2:Eu~(2)M MgCaSrBrAlF_3Eu~(2+)EuF
Resumo:
We present the first measurements of identified hadron production, azimuthal anisotropy, and pion interferometry from Au + Au collisions below the nominal injection energy at the BNL Relativistic Heavy-Ion Collider (RHIC) facility. The data were collected using the large acceptance solenoidal tracker at RHIC (STAR) detector at root s(NN) = 9.2 GeV from a test run of the collider in the year 2008. Midrapidity results on multiplicity density dN/dy in rapidity y, average transverse momentum < p(T)>, particle ratios, elliptic flow, and Hanbury-Brown-Twiss (HBT) radii are consistent with the corresponding results at similar root s(NN) from fixed-target experiments. Directed flow measurements are presented for both midrapidity and forward-rapidity regions. Furthermore the collision centrality dependence of identified particle dN/dy, < p(T)>, and particle ratios are discussed. These results also demonstrate that the capabilities of the STAR detector, although optimized for root s(NN) = 200 GeV, are suitable for the proposed QCD critical-point search and exploration of the QCD phase diagram at RHIC.
Resumo:
8-hydroxy-2'-deoxyguanosine (8OHdG) has been widely used as a biomarker of oxidative DNA damage in both animal models and human studies. To evaluate the effect of cigarette smoking on oxidative stress, we studied the levels of urinary 8OHdG from smokers and non-smokers and investigated the association with cigarette smoking. The urinary 8OHdG concentrations were determinated by capillary electrophoresis with end-column amprometric detection (CE-AD) after a single-step solid phase extraction (SPE), and then quantitatively expressed as a function of creatinine excretion. To increase the concentration sensitivity, a dynamic pH junction was used and the focusing effect was obvious when using 30 mM phosphate (pH 6.50) as sample matrix. The limit of detection is 4.3 nM (signal-to-noise ratio S/N = 3). The relative standard deviation (R.S.D.) was 1.1% for peak current, and 2.3% for migration time. Based on the selected CE-AD method, it was found that the mean value of urinary 8OHdG levels in the smokers significantly higher than that in non-smokers (31.4 +/- 18.9 nM versus 14.4 +/- 7.6 nM, P = 0.0004; 23.5 +/- 21.3 mug g(-1) creatinine versus 12.6 +/- 13.2 mug g(-1) creatinine, P = 0.028). (C) 2004 Elsevier B.V. All rights reserved.
Resumo:
addictionwithdraw symptomcAMPCREB1PTZ2-3NMDA 1Y 20.252.5 mg/kg21020 mg/kgY-2.5 mg/kg1020 mg/kg 330110 mg/kgY-NMDANMDA124 mg/kgNMDAMK-8010.050.10.2 mg/kg10 mg/kgNMDA2 mg/kg1 mg/kgMK-8010.05 mg/kg retinadorsal lateral geniculate nucleus, dLGNspatial resolution, SRhigh temporal frequency cut-off, TF50
Resumo:
A series of Zn(II) and Cd(II) metal-organic frameworks, namely, [Zn(DFDA)] (1), [Cd(DFDA)(C2H5OH)] (2), [Zn-2(DFDA)(2)(L-1)(2)](2) center dot 3H(2)O (3), [Cd-2(DFDA)(2)(L-1)(2)] (4), [Zn(DFDA)(L-2)] (5), [Cd(DFDA)(L-2)(DMF)] (6), and [Zn(DFDA)(L-3)] (7) (where DFDA = 9,9-dipropylfluorene-2,7-dicarboxylate anion, L-1 = 1,4-bis(imidazol-1-ylmethyl)benzene, L-2 = 1,1'-(1,4-butanediyl) bis(imidazole), L-3 = 2,2'-bipyridine) have been synthesized under hydrothermal conditions and structurally characterized. Compound 1 exhibits a three-dimensional (3D framework containing one-dimensional (1D) Zn(II)-O clusters, with (4(8).6(7)) topology. Compound 2 contains hydrophobic channels built from infinite 1D Cd(II)-O clusters, with (4(8).5(4).6(3)) topology.
Resumo:
The aim of this work is to study the effect of Sr substitution on the redox properties and catalytic activity of La2-xSrxNiO4 (x = 0.0-1.2) for NO decomposition. Results suggest that the x = 0.6 sample shows the highest activity. The characterization (TPD, TPR, etc.) of samples indicates that the x = 0.6 sample possesses suitable abilities in both oxidation and reduction, which facilitates the proceeding of oxygen desorption and NO adsorption. At temperature below 700 degrees C, the oxygen desorption is difficult, and is the rate-determining step of NO decomposition. With the increase of reaction temperature (T > 700 degrees C), the oxygen desorption is favorable and, the active adsorption of NO on the active site (NO + V-o + Ni2+ -> NO--Ni3+) turns out to be the rate-determining step. The existence of oxygen vacancy is the prerequisite condition for NO decomposition, but its quantity does not relate much to the activity.
Resumo:
When alkaline earth ions in borates, phosphates or borophosphates [SrB4O7, SrB6O10, BaB8O13, MBPO5 (M=Ca,Sr)] are substituted partially and aliovalently by trivalent rare earth ions such as Sm3+, Eu3+, these rare earth ions can be reduced to divalent state by the produced negative charge vacancy V-M". The matrices must have appropriate structure containing a rigid three-dimensional network of tetragonal AO(4) groups (A=B,P). These groups can surround and isolate the produced divalent RE2+ ions from the reaction with oxygen. Therefore, this reduction reaction can be carried out even in air at high temperature. The produced divalent rare earth ions can be detected by luminescence and XANES methods and their spectroscopic properties are discussed.
Resumo:
Two systems of mixed oxides, La2-xSrxCuO4 +/- lambda (0.0 less than or equal to x less than or equal to 1.0) and La(2-x)Tn(x)CuO(4 +/-) (lambda) (0.0 less than or equal to x less than or equal to 0.4), with K2NiF4 structure were prepared. The average valence of Cu ions and oxygen nonstoichiometry (lambda) were determined by means of chemical analysis. Meanwhile, the adsorption and activation of nitrogen monoxide (NO) and the mixture of NO + CO over the mixed oxide catalysts were studied by means of mass spectrometry temperature-programmed desorption (MS-TPD). The catalytic behaviors in the reactions of direct decomposition of NO and its reduction by CO were investigated, and were discussed in relation with average valence of Cu ions, A and the activation and adsorption of reactant molecules. It has been proposed that both reactions proceed by the redox mechanism, in which the oxygen vacancies and the lower-valent Cu ions play important roles in the individual step of the redox cycle. Oxygen vacancy is more significant for NO decomposition than for NO + CO reaction. For the NO + CO reaction, the stronger implication of the lower-valent Cu ions or oxygen vacancy depends on reaction temperature and the catalytic systems (Sr- or Th-substituted). (C) 2000 Elsevier Science B.V. All rights reserved.
