998 resultados para Sr^2
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The Pb2+ luminescence in a series of silicate oxyapatites Me(2)(Y, Gd)(8)(SiO4)(6)O-2, Me(4)Y(6)(SiO4)(6)O (Me = Mg: Ca, Sr) is reported and discussed in relation to the crystal structure. The maximum wavelengths of the excitation (S-1(0)-P-3(1)) and emission (P-3(1)-S-1(0)) bands of Pb2+ are independent of the Mc:Y ratio (2:8 or 4:6) but they have lower energies in MgY-oxyapatites than in CaY- and SrY-oxyapatites. The Stokes shift of Pb2+ luminescence amounts to 11 100 to 11 400 cm(-1): which does not depend strongly on the host composition. There exists a mutual energy transfer between Pb2+ and Gd3+ in Sr2Gd8(SiO4)(6)O-2. At last, the dependence of the energy transfer efficiency of Pb2+-Sm3+, Tb3+: Dy3+ in Sr-2(La: Gd)(8)(SiO4)(6)O-2 and Ca-2(Y, Gd)(8)(SiO4)(6)O-2 on their doping concentrations was studied in more detail.
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Laminaria japonicaSargassum pallidumS.kjellmanianum)s.thunbergii1. M/G1.861.501.221.27= (F_MG))/(F_M * F_G)0.620.130.360.412. Cd-SrM/GCu~(2+)MG-Sr~(2+)Ba~(2+)Cd~(2+)M-3. G-~(26)Cu~(2+)Sr~(2+) -COOHSr~(2+)Cu~(2+)Cu~(2+)Cu~(2+)Ca~(2+)Sr~(2+)4.
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Using a recently developed technique to extract jellyfish venom from nematocysts, the present study investigated the hemolytic activity of Cyanea nozakii Kishinouye nematocyst venom on chicken erythrocytes. Venom extract caused a significant concentration-dependent hemolytic effect. The extract could retain its activity at -80 degrees C but was unstable when kept at 4 degrees C and -20 degrees C for 2 days. The hemolytic activity was inhibited by heating within the range of 37-100 degrees C. The extract was active over a pH range of 5.0-8.63 and the pH optima for the extract was 7.8. Incubation of the venom with sphingomyelin specially inhibited hemolytic activity by up to 70%. Cu2+ and Mn2+ greatly reduced the hemolytic activity while Mg2+, Sr2+ and Ba2+ produced a relatively low inhibiting effect on the hemolytic activity. Treatment with Ca2+ induced a concentration-dependent increase in the hemolytic activity. In the presence of 5 mM EDTA, all the hemolytic activity was lost, however, the venom containing 1.5 mM EDTA was stable in the long-term storage. PLA(2) activity was also found in the nematocyst venom of C. nozakii. These characteristics provide us a fundamental knowledge in the C. nozakii nematocyst venom which would benefit future research. (C) 2010 Published by Elsevier Ltd.
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Sr^2+SrTZ^+2163meqL(TZ^+=0725meqL)Ca^2+HCO3^-Mg^2+SO4^2+Na^++K^+Cl^-+Si510Sr(11970mol/L)^87Sr^86Sr(0707707110)^87Sr^86Sr(0709007145)Sr(028132molL)3.
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10%13% 1NPKCaMgS1000 g∙g-1 FeMnAl100 g∙g¬-11000 g∙g¬-1ZnSr10 g∙g¬-1100 g∙g¬-1CuMo10 g∙g¬-1Mo(0.17 g∙g¬-1)CaPK FeMnSSrMgCa>K>Mg 2NPKMgCaAlFeMnCuZnSrMoSAlFeMnSr100%NPKCaMgSCu60%Ca(11.8%)PKPCuAlFeAlZnFeZnNPPMgKAlKCuCaSrSMo 32MnAlSr2.11.51.4 413C15N34S-26.98-29.15-4.08-0.79-8.69-6.04-28.14-2.41-7.5313C15N34S 513C15N34S13C15N34S13C15N34S13C34S15N
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COSr 1) FeMnSr Mn/Sr 2) -2-3 3) -2 4Locfit 12C CO2 4) (-11.75 ~ -21.13)(-5.14 ~-7.20)(-4.35 ~ -10.31)(-7.20-7.58-5.62-4.60-5.18-4.35) 5) -9.9-4.5 -3~-4FeMn (18O -3SMOW)5221 33 6) () 7)
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--()(H_20FBP)REE3-LCT3~(87)Sr~(86)Sr-f1) Y-HoZr-HfNb-TaSr-Eu(Irber 1999Bau 1997)3(1999)Sba and Chappell(1999)S()REES()(2) Sr~(2+)Eu~(2+)3SrEuIIlIIIIVSrEu(16:0111.2)VVIVIIIVSrEu(2466514:9IV10000)SrEuSrEu300SrEuEu~(2+)(3) 3IIIIII(~(11)B)-41.11-30.90VVIVII(~(11)B)-15.23-9.20IV-39.1913.10BYAILi~(11)B3B(-41.1l39.01)---3BB(4)3(II)3BePREE3IP(0.42 wt0.22 wt)IIIP(0.21 wt0.50 wt)IIP(0.08wt)PWatson (1978)Ryerson and Hess(1980)Webster et a1(1997EhrenfriedersdorfBe
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"()Sr~(87)Sr~(86)Sr~(87)Sr~(86)Sr222728~(87)Sr~(86)Sr~(87)Sr~(86)Sr(1)~(87)Rb~(87)Rb~(87)Sr~(87)Sr~(86)Sr~(87)Sr~(86)Sr(2)-~(87)Sr~(86)Sr-~(87)Sr~(86)Sr-SrCa(3)~(87)Sr~(86)Sr0.711900.712018~(87)Sr~(86)Sr0.7098070.709147O.7111(4)~(87)Sr~(86)SrSrCaMgCa(5)(1.OMa)
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Priodicit : Bimensuel
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Dans un bassin versant, la connectivit hydrologique constitue un tat hydrologique qui lie le versant la zone riveraine. Ses impacts sur la production du dbit et le transfert des lments dissous vers le cours deau sont prsums substantiels. Ltude vise 1) dtecter les hydrotopes et les connexions hydrologiques laide dun rseau de puits qui permet la mesure des fluctuations de la nappe phratique (NP); 2) identifier la variabilit spatio-temporelle et la signature gochimique des sources potentielles en eau laide des lments majeurs et traces et 3) examiner la contribution spatio-temporelle respective des sources en eau du bassin lors dun vnement de prcipitation. Ltude seffectue dans un bassin versant forestier du Bouclier canadien (lHermine). Nous dmontrons lexistence de quatre hydrotopes reprsentant un gradient de convergence de leau, soulignant la diversit de comportement de NP. Les connexions hydrologiques se caractrisent par des coefficients de Spearman levs des relations entre la profondeur de la NP et le dbit, dans leur partie en aval, et senclenchent par le fill and spill. Le comportement de NP est influenc par la distance aux limites du bassin, lhorizonation du sol et la topographie souterraine. En somme, trois sources en eau se connectent partir du versant vers la zone riveraine durant lvnement pluvial de manire chronologique: 1) les horizons B et la NP de lensemble du bassin (Sr); 2) les horizons LFH des zones de convergence (Ba et Zn) et 3) une dpression de sol humide sur le versant nord (Co et Mn).
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The objective of this thesis was to quantify the physiological responses such as O2 uptake (VO2), heart rate (HR) and blood lactate ([LA]) to some types of activities associated with intermittent sports in athletes. Our hypothesis is that the introduction of accelerations and decelerations with or without directional changes results in a significative increase of the oxygen consumption, heart rate and blood lactate. The purpose of the first study was to measure and compare the VO2 and the HR of 6 on-court tennis drills at both high and low displacement speeds. These drills were done with and without striking the ball, over full and half-width court, in attack or in defense mode, using backhand or forehand strokes. Results show that playing an attacking style requires 6.5% more energy than playing a defensive style (p < 0.01) and the backhand stroke required 7% more VO2 at low speed than forehand stroke (p < 0.05) while the additional cost of striking the ball lies between 3.5 and 3.0 mL kg-1 min-1. Finally, while striking the ball, the energy expanded during a shuttle displacement on half-width court is 14% higher than running on full-width court. Studies #2 and #3 focused on different modes of displacement observed in irregular sports. The objective of the second study was to measure and compare VO2, HR and [LA] responses to randomly performed multiple fractioned runs with directional changes (SR) and without directional changes (FR) to those of in-line running (IR) at speeds corresponding to 60, 70 and 80% of the subjects maximal aerobic speed (MAS). All results show that IRs VO2 was significantly lower than SRs and FRs (p<0.05). SRs VO2 was greater than FRs only at speeds corresponding to 80%MAS. On the other hand, HR was similar in SR and FR but significantly higher than IRs (p<0.05). [LA] varied between 4.2 0.8 and 6.6 0.9 mmol L-1 without significant differences between the 3 displacement modes. Finally, the third studys objective was to measure and compare VO2 , HR and [LA] responses during directional changes at different angles and at different submaximal running speeds corresponding to 60, 70 and 80% MAS. Subjects randomly performed 4 running protocols 1) a 20-m shuttle running course (180) (SR), 2) an 8-shaped running course with 90-degree turns every 20 m (90R), 3) a Zigzag running course (ZZR) with multiple close directional changes (~ 5 m) at different angle values of 91.8, 90 and 38.6, 4) an In-line run (IR) for comparison purposes. Results show that IRs was lower (p<0.001) than for 90Rs, SRs and ZZRs at all intensities. VO2 obtained at 60 and 70%MAS was 48.7 and 38.1% higher during ZZR when compared to IR while and depending on the intensity, during 90R and SR was between 15.5 and 19.6% higher than during IR. Also, ZZRs VO2 was 26.1 and 19.5% higher than 90Rs, 26.1 and 15.5% higher than SRs at 60 and 70%MAS. SRs and 90Rs VO2 were similar. Changing direction at a 90 angle and at 180 angle seem similar when compared to continuous in-line running. [LA] levels were similar in all modalities. Overall, the studies presented in this thesis allow the quantification of the specific energetic demands of certain types of displacement modes in comparison with conventional forward running. Also, our results confirm that the energy cost varies and increase with the introduction of accelerations and decelerations with and without directional changes.
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Self-assembled monolayers (SAMs) on solid surfaces are of great current interest in science and nanotechnology. This thesis describes the preparation of several symmetrically 1,1-substituted ferrocene derivatives that contain anchoring groups suitable for chemisorption on gold and may give rise to SAMs with electrochemically switchable properties. The binding groups are isocyano (-NC), isothiocyanato (-NCS), phosphanyl (-PPh2), thioether (-SR) and thienyl. In the context of SAM fabrication, isothiocyanates and phosphanes are adsorbate systems which, surprisingly, have remained essentially unexplored. SAMs on gold have been fabricated with the adsorbates from solution and investigated primarily by X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy. The results of these analytical investigations are presented and discussed in matters of the film quality and possible binding modes. The quality of self-assembled monolayers fabricated from 1,1-diisocyanoferrocene and 1,1-diisothiocyanatoferrocene turned out to be superior to that of films based on the other adsorbate species investigated. Films of those absorbates as well as of dppf afforded well-defined SAMs of good quality. All other films of this study based on sulfur containing anchoring groups exhibit chemical inhomogeneity and low orientational order of the film constituents and therefore failed to give rise to well-defined SAMs. Surface coordination chemistry is naturally related to molecular coordination chemistry. Since all SAMs described in this thesis were prepared on gold (111) surfaces, the ferrocene-based ligands of this study have been investigated in their ability for complexation towards gold(I). The sulfur-based ferrocene ligands [fc(SR)2] failed to give stable gold(I) complexes. In contrast, 1,1-diisocyanoferrocene (1) proved to be an excellent ligand for the complexation of gold(I). Several complexes were prepared and characterised utilising a series of gold(I) acetylides. These complexes show interesting structural motifs in the solid state, since intramolecular aurophilic interactions lead to a parallel orientation of the isocyano moieties, combined with an antiparallel alignment of neighbouring units. The reaction of 1 with the gold(I) acetylide [Au(CCFc)]n turned out to be very unusual, since the two chemically equivalent isocyano groups undergo a different reaction. One group shows an ordinary coordination and the other one undergoes an extraordinary 1,1-insertion into the Au-C bond. As a sideline of the research of this thesis several ferrocene derivatives have been tested for their suitability for potential surface reactions. Copper(I) mediated 1,3-dipolar cycloadditions of azidoferrocene derivatives with terminal alkynes appeared very promising in this context, but failed to a certain extent in terms of click chemistry, since the formation of the triazoles depended on the strict exclusion of oxygen and moisture and yields were only moderate. Staudinger reactions between dppf and azidoferrocene derivatives were also tested. The nucleophilic additions of secondary amines to 1,1-diisothiocyanatoferrocene led to the respective thiourea derivatives in quantitative yields.
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Fundao de Amparo Pesquisa do Estado de So Paulo (FAPESP)
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Lead zirconate powder, with Zr/Ti ratio of 50/50 was prepared by polymeric precursor method and doped with 3, 5 and 7 mol% of Sr+2 Or Ba+2, as well as by 0.2 to 5 mol% of Nb+5. The powder was calcined at 750 degrees C by 4 hours and milled during 1.5 h in isopropilic alcohol. Powders were characterized by surface area measurements (BET method), by infrared spectroscopy and by X-ray diffraction to characterize the crystal structure. Isostatically pressed samples were sintered in a dilatometer furnace by using a constant heating rate of 10 degrees C/min from ambient to 1200 degrees C. Synthetic air and air with water vapor were used as atmospheres. Both Sr+2 and Ba+2 substitute Pb+2 and favor the formation of rhombohedral phase. Otherwise, Nb+5 substitute preferentially Zr+4 favoring tetragonal phase. The concentration of dopants and the atmosphere influence the densification and the microstructure of the PZT, which alters the dielectric and piezoelectric properties of the ceramics.
