Propolis has been the subject of several recent studies, with the aim of elucidating its biological and pharmacological properties. Propolis has a well-known antimicrobial activity as well as antioxidant, antitumoral, antiinflammatory, and regenerative properties, but literature about its effects on the immune response is scarce. The goal of this work was to evaluate the propolis effect on macrophage activation by oxygen (H2O2) and nitrogen (NO) metabolite determination. Propolis was produced by africanized honeybees and hydroalcoholic solutions were prepared at different concentrations. Peritoneal macrophages were obtained from male BALB/c mice and culture cells were stimulated in vitro with propolis or interferon-gamma (IFN-gamma). In the in vivo assay, the animals were sacrificed after propolis treatment and cells were stimulated with IFN-gamma. We also investigated the co-stimulant action of propolis associated with IFN-gamma on macrophages. The results show that propolis induces a discreet elevation in H2O2 release and a mild inhibition of NO generation, depending on concentration. Propolis had no co-stimulant activity, diminishing IFN-gamma action on H2O2 and NO production. Data suggest that propolis acts on host non-specific immunity by macrophage activation

We report on the degenerate two-photon absorption (2PA) spectra of perylene tetracarboxylic derivatives (PTCDs), bis-(benzimidazo)perylene (AzoPTCD), and bis(benzimidazo)-thioperylene (Monothio BZP), obtained by means of the Z-scan technique with femtosecond laser pulses. The results show that these materials possess exceptionally high 2PA cross-sections. At 750 nm, for instance, AzoPTCD and Monothio BZP present 2PA cross-sections of 3400 10 ±50 cm 4 s photon ±1 and 1170 10 ±50 cm 4 s photon ±1, respectively. In addition, the 2PA saturation behavior observed as the laser irradiance increases and the strong two-photon-induced fluorescence suggest that PTCD compounds may be attractive candidates for applications in optical limiting and two-photon pumped (2PP) upconversion lasing.Upon exposure to intense laser pulses, molecules can instantaneously absorb two photons to access an excited state, each of them with half of the energy required to match the electronic transition. Such a 2PA process has interesting characteristics with direct consequences to applications including: i) improved spatial resolution owing to the square dependence on the excitation irradiance; ii) negligible linear absorption at the pumping wavelength, with a resulting increase of penetration depth, particularly in biological tissues; and iii) very fast temporal response. The advantages of the 2PA mechanism have been explored in numerous studies leading to promising applications, such as 2PP frequencyupconverted lasing, optical limiting, fluorescence excitation microscopy and imaging, three-dimensional optical data storage and lithographic microfabrication, and photodynamic therapy.[1±8] Accordingly, a great deal of effort has been directed to the development of various design strategies to synthesize new two-photon absorbing materials with large 2PA cross-sections (d) and to increase physical and chemical stabilities. Most of the recently developed two-photon absorbers are organic compounds. [2,5,9±15] Here, we investigate the possibility of using PTCD dyes as materials with high nonlinear optical absorption. PTCDs are organic dyes, readily available and thermally and chemically stable. The perylene moiety presents remarkable electron-donor characteristics, [16,17] although on adding lateral groups, the molecule can play either an electron-acceptor or -donor role. Moreover, their strong absorption and emission in the visible spectral range makes them potential candidates for applications as organic semiconductors, photoconductors, and laser materials.[16±22]Although high optical nonlinearities have been reported in organic materials at specific wavelengths, only recently has the dispersion of the nonlinear absorption over a wide spectral range begun to be characterized. [2,5,7,13±15,23±26] From an applications point of view, such information is important in formulating a molecular design strategy for a given nonlinear optical material. In this context, the present work reports on the degenerate 2PA cross-section spectra of AzoPTCD and Monot...

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High‐resolution solid‐state 31P, 27Al, and 23Na nuclear magnetic resonance (NMR), Raman spectroscopy, differential scanning calorimetry, and density measurements were used to characterize the local structure of the glasses (1−x)(NaPO3)3·xAl(PO3)3. A systematic increase in density, glass transition temperature (Tg), and frequencies of P–O stretching vibrations for terminal nonbridging oxygens (NBOs) was observed as the Al content was increased. A change of slope in the behavior of Tg as a function of x was clearly detected around x= 0.25 ± 0.03. Also, changes of behavior in the 23Na NMR line shape and in the Raman band of the PO2 symmetric vibration are detected for concentrations higher than x= 0.17. According to these facts, a reorganization of the network affecting the degree of connectivity between phosphate chains is proposed to explain the observed behaviors of Tg and P–NBO vibrations in these glasses.

In this paper we present results on cooperative luminescence performed on Yb3+-doped metaphosphate glasses under 980 nm excitation. We have measured emission spectra and decay lifetimes in the visible and infrared regions as a function of Yb concentration. It was observed that, up to 10% of Yb concentration, cooperative emission increases while lifetime is observed to decrease. Such behaviour is attributed to the Yb interaction with OH− radicals and energy migration among Yb ions.

Paracoccidioides brasiliensis and the related species P. americana, P. restrepiensis, P. venezuelensis, and P. lutzii (Ascomycota, Ajellomycetaceae) are the etiological agents of paracoccidoidoimycosis (PCM), one of the most important systemic mycoses in Latin America. They are dimorphic fungi, with a mycelial life cycle in soil and a yeast phase associated with tissues of mammalian hosts. This study aimed to detect Paracoccidioides spp. in armadillo tissues and associated soil samples in three well-defined geographic areas, including the Alta Floresta, an area not only endemic for PCM in the central region of Brazil but also of probable P. lutzii occurrence, whose ecology and geographic distribution are poorly elucidated. The isolates were genotyped by sequencing ITS-rDNA and the gp43-exon-2 region, and by PCR-RFLP of alpha tubulin (tub1) gene; mycological aspects such as yeast-to-mycelial transition, growth and conidial production in soil extract agar were also evaluated. We confirmed that while armadillos are highly infected by P. brasiliensis, including multiple infections by distinct genotypes or species (P. brasiliensis and P. americana) in the same animal, the same does not hold true for P. lutzii, which in turn seems to present less capacity for mycelial growth and conidial production, when developing in a soil-related condition.

We present a new method based on thermal lens ͑TL͒ technique to determine the fluorescence quantum efficiency, , and thermo-optical coefficients of fluorescent materials. These parameters can be obtained from the linear dependence of the TL signal with the experimental lifetimes of a set of samples with different luminescent ion concentrations. The method was applied in Nd 3+ -doped materials ͑Q-98 Phosphate, fluorozirconate, and fluoroindate͒. The obtained values are in agreement with those determined by other approaches based on TL methods and the ratio between experimental and radiative lifetime values ͑Judd-Ofelt theory͒. The method hereafter presented is very simple and does not require comparison with a reference sample or the use of multiple excitation wavelengths. In addition, the nature of concentration quenching taking into account the achieved and values and respective energy transfer microparameters, is discussed.

We investigated the 2PA absorption spectrum of a family of perylene tetracarboxylic derivatives (PTCDs): bis(benzimidazo)perylene (AzoPTCD), bis(benzimidazo)thioperylene (Monothio BZP), n-pentylimidobenzimidazoperylene (PazoPTCD), and bis(n-butylimido)perylene (BuPTCD). These compounds present extremely high two-photon absorption, which makes them attractive for applications in photonics devices. The two-photon absorption cross-section spectra of perylene derivatives obtained via Z-scan technique were fitted by means of a sum-over-states (SOS) model, which described with accuracy the different regions of the 2PA cross-section spectra. Frontier molecular orbital calculations show that all molecules present similar features, indicating that nonlinear optical properties in PTCDs are mainly determined by the central portion of the molecule, with minimal effect from the lateral side groups. In general, our results pointed out that the differences in the 2PA cross-sections among the compounds are mainly due to the nonlinearity resonance enhancement.