Structural and luminescence properties of Eu3+ doped BaxSr1 12xTiO3 (BST) nanocrystalline powders prepared by different methods

Eu3+ doped BaxSr1-xTiO3 (BST) nanocrystalline powders have been prepared using molten salts, sol-gel and hydrothermal techniques in order to compare their structural and luminescence properties. The sizes of the particles are around 50 nm for the BST powders obtained by the sol-gel and hydrothermal methods while they are around 400 nm for the samples prepared by the molten salts method. The Eu3+ doped BST samples show strong emission in the visible range. The luminescence spectra of the Eu3+ ions for the investigated samples depend strongly upon the preparation method. The luminescence bands are affected by a notable amount of inhomogeneous broadening. The broadening of the emission bands and the non-exponential behavior of the emission decay curves point to the presence of significant structural disorder

Advanced oxidation treatment of pentoxifylline in aqueous solutions

The degradation of pentoxifylline (PTX) using H2O2, UV, H2O2/UV, Fenton and photo-Fenton processes has been examined in aqueous solutions. The influence of oxidation agent and initial PTX concentration, on H2O2, H2O2/UV, Fenton and photo-Fenton reactions was investigated. The addition of inorganic ions (Cl–, NO3–, SO42– and CO32–) on the degradation efficiency of PTX was tested for H2O2/UV, Fenton and photo-Fenton processeses. The results indicate that the photo-Fenton reaction is the most sufficient for PTX removal. The complete pharmaceutics decomposition is achieved after 5 min under optimized concentration of FeSO4,·7 H2O2 and H2O2. The degradation of PTX is inhibited in the presence of inorganic matter in H2O2/UV and Fenton reaction. In the photo-Fenton process addition of above compounds does not affect the reaction rate. Structures of ten products of photo-Fenton reaction have been proposed

Placebo-controlled trial of cytisine for smoking cessation.

BACKGROUND: Cytisine, a partial agonist that binds with high affinity to the α(4)β(2) nicotinic acetylcholine receptor, is a low-cost treatment that may be effective in aiding smoking cessation. This study assessed the efficacy and safety of cytisine as compared with placebo. METHODS: We conducted a single-center, randomized, double-blind, placebo-controlled trial. Participants were randomly assigned to receive cytisine or matching placebo for 25 days; participants in both groups received a minimal amount of counseling during the study. The primary outcome measure was sustained, biochemically verified smoking abstinence for 12 months after the end of treatment. Of 1542 adult smokers screened, 740 were enrolled and 370 were randomly assigned to each study group. RESULTS: The rate of sustained 12-month abstinence was 8.4% (31 participants) in the cytisine group as compared with 2.4% (9 participants) in the placebo group (difference, 6.0 percentage points; 95% confidence interval [CI], 2.7 to 9.2; P=0.001). The 7-day point prevalence for abstinence at the 12-month follow-up was 13.2% in the cytisine group versus 7.3% in the placebo group (P=0.01). Gastrointestinal adverse events were reported more frequently in the cytisine group (difference, 5.7 percentage points; 95% CI, 1.2 to 10.2). CONCLUSIONS: In this single-center study, cytisine was more effective than placebo for smoking cessation. The lower price of cytisine as compared with that of other pharmacotherapies for smoking cessation may make it an affordable treatment to advance smoking cessation globally

Structural and spectroscopic features of Ca9M(PO4)7 (M\ua0=\ua0Al3+, Lu3+) whitlockites doped with Pr3+ ions

In this work we present the structural and spectroscopic properties of Ca9M(PO4)7 (M = Al, Lu) whitlockite compounds doped with Pr3+ ions. The Al containing samples were prepared by the citrate route, while the Lu based samples were prepared by standard solid state reaction. The structural properties were investigated by XRD measurements and Rietveld analysis. Detailed spectroscopic properties like emission and excitation spectra, luminescence kinetics and luminescence temperature quenching were measured to determine the influence of different trivalent host metal on the Pr3+ ions. Pr3+ enter in the three Ca2+ sites in the Ca9Al(PO4)7 compounds, creating some defect to compensate the charge mismatch, whereas in the Ca9Lu(PO4)7 Pr3+ ions occupy four Ca2+/Lu3+ sites, where no charge compensation is needed. The emission spectra are similar for both materials. Efficient quenching of the 1D2 emission was observed, while the 3P0 emission remains stable for all dopant concentrations. Decay times were found to be non-single exponential due to the occupation of different sites by the Pr3+ ions. The luminescence temperature quenching measurements have revealed that two different mechanisms (multi-phonon relaxation and cross-relaxation processes) are responsible for the emission quenchin

Multifunctional lanthanide and silver ions co-doped nano-chlorapatites with combined spectroscopic and antimicrobial properties.

International audienceNanocrystalline chlorapatites (Ca10(PO4)6Cl2) doped with lanthanide ions (Eu3+, Er3+ and Yb3+) and co-doped with silver ions (Ag+) were synthesized by a hydrothermal synthesis route. XRD, TEM, and SAED measurements indicated that the powders are single phased and crystallize with a hexagonal structure with good dispersion. The results showed well crystallized chlorapatite grains with a diameter of about 45 nm. The antimicrobial activity of the nanoparticles against Escherichia coli ATCC 11229 and ATCC 25922, Klebsiella pneumoniae ATCC 700603, and Pseudomonas aeruginosa PAO1 and ATCC 27853 was studied. The best activity was observed for the Eu3+,Ag+:Ca10(PO4)6Cl2 and Eu3+,Ag+,Yb3+:Ca10(PO4)6Cl2 compositions. These multifunctional nanocrystalline powders could be used as a promising antimicrobial agent and material for bio-detection

Second harmonic generation and Yb3+^{3+} cooperative emission as unusual ways to probe phase transitions in BaTiO3_{3} sol-gel nanocrystals

Nanocrystalline powders of 1% Yb$^{3+}$-doped BaTiO$_{3}$ sintered at different temperatures were obtained by the sol-gel method. The structure of the powders covering crystallite-sizes from 25 to 60 nm depending on the annealing temperature ($700-1200^{\circ}$C) was determined from the Scherrer's equation. Second Harmonic Generation (SHG) intensity magnitude is compared in each samples of the tetragonal BaTiO$_{3}$ whereas the isotropic cubic phase is detected by the absence of the SHG signal. Cooperative emission, indicating the Yb$^{3+}$ ions pairs, was easily detected in the cubic phase and not seen in the ferroelectric tetragonal structure