Low-level laser therapy for the prevention of low salivary flow rate after radiotherapy and chemotherapy in patients with head and neck cancer

Abstract Objective: To determine whether low-level laser therapy can prevent salivary hypofunction after radiotherapy and chemotherapy in head and neck cancer patients. Materials and Methods: We evaluated 23 head and neck cancer patients, of whom 13 received laser therapy and 10 received clinical care only. An InGaAlP laser was used intra-orally (at 660 nm and 40 mW) at a mean dose of 10.0 J/cm2 and extra-orally (at 780 nm and 15 mW) at a mean dose of 3.7 J/cm2, three times per week, on alternate days. Stimulated and unstimulated sialometry tests were performed before the first radiotherapy and chemotherapy sessions (N0) and at 30 days after the end of treatment (N30). Results: At N30, the mean salivary flow rates were significantly higher among the laser therapy patients than among the patients who received clinical care only, in the stimulated and unstimulated sialometry tests (p = 0.0131 and p = 0.0143, respectively). Conclusion: Low-level laser therapy, administered concomitantly with radiotherapy and chemotherapy, appears to mitigate treatment-induced salivary hypofunction in patients with head and neck cancer.

Discrepancies over the onset of surfactant monomer aggregation interpreted by fluorescence, conductivity and surface tension methods

Molecular probe techniques have made important contributions to the determination of microstructure of surfactant assemblies such as size, stability, micropolarity and conformation. Conductivity and surface tension were used to determine the critical aggregation concentration (cac) of polymer-surfactant complexes and the critical micellar concentration (cmc) of aqueous micellar aggregates. The results are compared with those of fluorescent techniques. Several surfactant systems were examined, 1-butanol-sodium dodecylsulfate (SDS) mixtures, solutions containing poly(ethylene oxide)-SDS, poly(vinylpyrrolidone)-SDS and poly(acrylic acid)-alkyltrimethylammonium bromide complexes. We found differences between the cac and cmc values obtained by conductivity or surface tension and those obtained by techniques which use hydrophobic probe.

X-ray fluorescence determination of adsorbed copper on activated charcoal after glycerin complexation

X-This work shows an alternative method to copper determination by X-Ray Fluorescence (XRF). Since copper concentration in natural waters is not enough to reach XRF detection limit, a liquid-solid preconcentration procedure was proposed. Glycerin was used to complex the metal increasing its adsorption on activated charcoal. The solid phase was used to XRF determination. Several parameters were evaluated, such as, the complexation pH, the charcoal adsorption limit and the glycerin concentration. The interferences are lead and bismuth and the sensitivities decreased in the order Cu2+, Bi3+ and Pb2+. The advantages of the method are its simplicity, low cost and low spectral interference.

Fotólise no estado estacionário e com pulso de laser de 1-benzociclanonas e de seus derivados a,a -dimetilados

Laser excitation of 0.01 M solutions of 1-indanone (Ia), 1-tetralone (Ib), 1-benzosuberone (Ic), and their a,a -dimethyl derivatives IIa-c, respectively, in benzene, produced transients with maximum absorption at 425 nm, and lifetimes ranging from 62 ns (IIa) to 5.5ms (Ic). Quenching studies using well known triplet quenchers such as 1,3-cyclohexadiene and oxygen demonstrated the triplet nature of these transients. In the presence of hydrogen donors, such as 2-propanol, the triplet state decay of the ketones Ia-c leads to the formation of the corresponding ketyl radicals, i.e. IIIa-c, which show absorption spectra very similar to the parent ketone, with lmax at 430 nm and lifetime in excess of 20 ms. Steady state irradiations show that the a,a -dimethyl ketones IIa and IIc form ortho-alkyl benzaldehydes probably derived from an initial a-cleavage of the corresponding triplet excited states.

A técnica da reflectância difusa aplicada ao estudo da fluorescência de 2,3-naftalimidas n-substituídas com grupos alquila incluídas em b-ciclodextrina e adsorvidas em celulose microcristalina

The solution fluorescence of N-alkyl-2,3-naphthalimides (1-4) in polar protic and aprotic solvents was compared to the emission from solid samples resulting from the imide complexation with b-cyclodextrin or adsorption on the surface of microcrystalline cellulose. Solid samples of the inclusion complex 2,3-naphthalimides/b-cyclodextrin show maximum for fluorescence emission significantly different to the observed in methanolic solution. Beside this, a clear effect on the alkyl chain length could be observed for these samples which is probably due to differences in probe location inside the cyclodextrin cavity. The constancy for fluorescence quantum yield and fluorescence lifetime for the imides 1 - 4 adsorbed on microcrystalline cellulose suggests that, independently of the polarity of the solvent used for sample preparation, the probe is preferentially located on the cellulose surface. An increase of fluorescence quantum yield and fluorescence lifetime for solid samples, when compared to the values obtained in solution for the different solvents employed in this study (acetonitrile, methanol and water), is fully in accordance with a decrease of the probe mobility due to inclusion in b-cyclodextrin or to adsorption on cellulose.

Estudo espectroscópico de vidros a base de aluminato de cálcio contendo Nd3+

Multicomponent ( Al2O3, CaO, SiO2, MgO) calcium aluminate-based glasses containing Nd3+ were prepared in order to evaluate their possibilities as laser host materials. The refractive index, UV-visible-near IR absorption spectrum, IR and visible luminescence spectra, and fluorescence decay time were measured. Judd-Ofelt model was used to obtain experimental intensity parameters ( omega2, omega4 and omega6), emission cross-section, radiative lifetimes, emission branching ratios and quantum efficiency.

Fotodegradação de hidrocarbonetos policíclicos aromáticos em placas de sílica impregnadas com dióxido de titânio

Photodegradation of the PAHs anthracene, chrysene and benzo[k]fluoranthane on silica gel impregnated with TiO2 and over glass plates holding TiO2 was studied. Silica gel plates holding these substances were exposed to solar radiation, developed with hexane and photographed under ultra-violet light. The plates containing benzo[k]fluoranthene were also analysed by both diffuse reflectance and laser induced fluorescence. Diffuse reflectance spectra of the fluorescent spot from non irradiated plates showed small differences when compared with those obtained from irradiated plates. These spectral differences are compatible with formation of less conjugated compounds during irradiation. Fluorescence and time resolved fluorescence spectra observed after irradiation were identical to those obtained with benzo[k]fluoranthene in methanol. On plates holding silica, PAH degradation requires longer periods of solar irradiation when compared with those plates containing silica impregnated with TiO2. Glass plates impregnated with TiO2 also showed very rapid PAH degradation.

Determination of ochratoxin A in coriander (Coriandrum sativum L.) by HPCL/fluorescence detection

An analytical study based on extraction with acetonitrile-water, immunoaffinity column cleanup, and HPLC/fluorescence detection for separation and identification of ochratoxin A in coriander was carried out. Validation of the applied methodology was done through accuracy and precision studies. Homogenized samples of coriander were spiked in triplicate with ochratoxin A at 0.5, 1.0, 2.0, and 5.0 µg/kg levels. Recovery values were in the range of 98% for a fortification level at 0.5 µg/kg to 109.1% at 1.0 µg/kg. Application to coriander samples available in Portuguese markes showed no contamination with ochratoxin A.

Photomultiplier nonlinear response in time-domain laser-induced luminescence spectroscopy

A new procedure to find the limiting range of the photomultiplier linear response of a low-cost, digital oscilloscope-based time-resolved laser-induced luminescence spectrometer (TRLS), is presented. A systematic investigation on the instrument response function with different signal input terminations, and the relationship between the luminescence intensity reaching the photomultiplier and the measured decay time are described. These investigations establish that setting the maximum intensity of the luminescence signal below 0.3V guarantees, for signal input terminations equal or higher than 99.7 ohm, a linear photomultiplier response.

Determinação da humificação da matéria orgânica de um latossolo e de suas frações organo-minerais

Laser-induced fluorescence spectroscopy was used to determine the humification degree of the organic matter of a whole soil, that is, soil without any physical or chemical treatment. Particle size was determined in physically separated fractions. The humification of organic matter, the depth of the soil and the planting system can be correlated. On the surface of the soil, no tillage provided the smallest humification in comparison with the conventional tillage and reduced tillage. The fractions of the superficial layer of the soil (0-20 cm) indicated larger humification in the fraction from 20 to 53 µm and the smallest in the fraction of <2 µm.

Líquido iônico [bmim.PF6] como solvente: um meio conveniente para estudos por fotólise por pulso de laser

The spectroscopic behavior of thioxanthone and benzil (diphenylethanedione or dibenzoyl) in the ionic liquid [bmim.PF6] has been investigated employing the laser flash photolysis technique. Triplet-triplet absorption spectra for these carbonyl compounds in [bmim.PF6] are similar to those observed in organic solvents. The triplet lifetime for thioxanthone in desogygenated samples is very long (71 μs), whereas in oxygen-saturated solution is 500 ns, which indicates the low oxygen solubility in this solvent. For benzil, lifetimes of 10 μs in [bmim.PF6] and 3.8 μs in acetonitrile were obtained. The decay for triplet thioxanthone and benzil follows a clear first order kinetics in [bmim.PF6], from which one can conclude that triplet-triplet annihilation is not an important decay process in this solvent.

Processamento e caracterização de espumas vitrocerâmicas do sistema sncp (Sio2-Na2o-Cao-P2 O5)

Glass-ceramics foams prepared from glasses of the SiO2-Na2O-CaO-P2O5 by replication process were obtained and characterized in terms of their chemical and physical properties by X-ray fluorescence, X-ray diffraction, laser diffraction, thermal analysis, density, mechanical strength, microstructural and cytotoxic analysis. The results showed that it is possible to produce glass-ceramic foams by the replication method with optimized properties but cytotoxic analysis indicates that the glass-ceramic foams are not bioactive materials. Mechanical strength values varying from 0.5 to 1.0 MPa and from 0.8 to 2.3 MPa were reached for mean particle sizes of 10 and 6 µm, respectively.

Obtaining high purity silica from rice hulls

Many routes for extracting silica from rice hulls are based on direct calcining. These methods, though, often produce silica contaminated with inorganic impurities. This work presents the study of a strategy for obtaining silica from rice hulls with a purity level adequate for applications in electronics. The technique is based on two leaching steps, using respectively aqua regia and Piranha solutions, which extract the organic matrix and inorganic impurities. The material was characterized by Fourier-transform infrared spectroscopy (FTIR), powder x-ray diffraction (XRD), x-ray fluorescence (XRF), scanning electron microscopy (SEM), particle size analysis by laser diffraction (LPSA) and thermal analysis.

A fluorescence-based assay for octreotide in kinetic release from depot formulations

Here we report the validation of a derivatization method that makes use of fluorescamine as a selective reactant for the quantitative analysis of peptide and protein drugs in the dissolution profile from depot formulations. Typical current methods require separation of the nano/microparticles and time-consuming chromatographic runs. In this study we report a method which can be conducted without the need for complete physical separation of the particles or removal of the unreacted probe. This method was used here for the analysis of the release profile of octreotide in a depot formulation, with results in excellent agreement with reported chromatographic assays.

Fe3+-SELECTIVE ENHANCED FLUORESCENCE PROBE BASED ON A RHODAMINE DERIVATIVE

A novel Fe3+-selective and turn-on fluorescent probe 1 incorporating a rhodamine fluorophore and quinoline subunit was synthesized. Probe 1 displayed high selectivity for Fe3+ in CH3CN–H2O (95:5 v/v) in the presence of other relevant metal cations. Interaction with Fe3+ in 1:1 stoichiometry could trigger a significant fluorescence enhancement due to the formation of the ring-open form. The fluorescent response images were investigated by a novel Euclidean distance method based on red, green, and blue values. A linear relationship was observed between fluorescence intensity changes and Fe3+ concentrations from 7.3 × 10−7 to 3.6 × 10−5 mol L−1.