Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto

About: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto is a based out in . It is known for research contribution in the topics: Population & Catalysis. The organization has 2143 authors who have published 3674 publications receiving 71071 citations. The organization is also known as: FFCLRP & FFCLRP-USP.

Computational Study about Through-Bond and Through-Space Interactions in [2.2]Cyclophanes

Abstract: An analysis of the electron density, obtained by B3PW91/6-31+G(d,p), B3LYP/6-31+G(d,p), and MP2/6-31+G(d,p) for [2,2]cyclophanes isomers, [2.2]paracyclophane, anti-[2.2]metacyclophane, syn-[2.2]metacyclophane, and [2.2]metaparacyclophane, was made through natural bond orbitals (NBO), natural steric analysis (NSA), and atoms in molecules (AIM) methods and through analysis of frontier molecular orbitals (MOs). NBO indicates that all compounds present through-bond interactions, but only the conformers of [2.2]metacyclophane present significant through-space interactions. The last interactions are observed in AIM analysis and by the plots of MOs. AIM indicates that these through-space interactions are closed-shell ones, and they stabilize the conformers. In contrast, all isomers present through-bond and through-space repulsive interactions. In addition, the atomic properties, computed over the atomic basins, showed that the position of the bridges and the relative displacement of the rings can affect the atom...

Synthesis and Luminescent Properties of REVO4–REPO4 (RE = Y, Eu, Gd, Er, Tm, or Yb) Heteronanostructures: A Promising Class of Phosphors for Excitation from NIR to VUV

Abstract: Despite presenting very similar structural properties, rare earth (RE) phosphate and vanadate solids display different spectroscopic behaviors, which makes the elaboration of REVO4–REPO4 mixed structures an interesting prospect for the design of luminescent materials with improved activity. This work describes the application of a two-step colloidal precipitation approach for the formation of REVO4–REPO4 heteronanostructures and an investigation of their luminescent properties. The growth of the phosphate phase over REVO4 particles was kinetically evaluated through spectroscopic methodologies comprising the observation of the VO43– → Eu3+ energy transfer and the absorption of vanadium(V) peroxocomplexes in solution. This confirmed an effective coating of the precursor nanoparticles. In order to obtain materials with enhanced properties, a protected annealing methodology in SiO2 was applied, leading to highly crystalline nanorods with low degree of aggregation. The final materials display efficient emissio...

Na+, K+-ATPase activity in gill microsomes from the blue crab, Callinectes danae, acclimated to low salinity: novel perspectives on ammonia excretion.

Abstract: This investigation provides an extensive characterization of the modulation by ATP, Mg 2+ , Na + , K + and NH 4 + of a gill microsomal (Na + ,K + )-ATPase from Callinectes danae acclimated to 15‰ salinity. Novel findings are the lack of high-affinity ATP-binding sites and a 10-fold increase in enzyme affinity for K + modulated by NH 4 + , discussed regarding NH 4 + excretion in benthic marine crabs. The (Na + ,K + )-ATPase hydrolyzed ATP at a maximum rate of 298.7 ± 16.7 nmol Pi min − 1 mg − 1 and K 0.5 = 174.2 ± 9.8 mmol L − 1 , obeying cooperative kinetics ( n H = 1.2). Stimulation by sodium ( V = 308.9 ± 15.7 nmol Pi min − 1 mg − 1 , K 0.5 = 7.8 ± 0.4 mmol L − 1 ), magnesium (299.2 ± 14.1 nmol Pi min − 1 mg − 1 , K 0.5 = 767.3 ± 36.1 mmol L − 1 ), potassium (300.6 ± 15.3 nmol Pi min − 1 mg − 1 , K 0.5 = 1.6 ± 0.08 mmol L − 1 ) and ammonium ( V = 345.1 ± 19.0 nmol Pi min − 1 mg − 1 , K 0.5 = 6.0 ± 0.3 mmol L − 1 ) ions showed site–site interactions. Ouabain inhibited (Na + ,K + )-ATPase activity with K I = 45.1 ± 2.5 μmol L − 1 , although affinity for the inhibitor increased ( K I = 22.7 ± 1.1 μmol L − 1 ) in 50 mmol L − 1 NH 4 + . Inhibition assays using ouabain plus oligomycin or ethacrynic acid suggest mitochondrial F 0 F 1 - and K + -ATPase activities, respectively. Ammonium and potassium ions synergistically stimulated specific activity up to 72%, inferring that these ions bind to different sites on the enzyme molecule, each modulating stimulation by the other.