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Considering the antioxidant activity of the Trichilia catigua extract (TCE), the aim of the current study was to develop and characterize W/O/W multiple emulsions containing different vegetable oils as a platform to deliver a TCE. The extract displayed antioxidant activity (IC50) of 4.59 µg/mL and total phenol content (TPC) of 50.84%. Formulations were prepared by the phase-inversion emulsification method and analyzed for morphological appearance, pH, conductivity, droplet size and distribution, content of active, rheological properties, in vitro release, skin permeation, and stability. Formulations prepared with canola oil were selected and displayed regular morphology, mean diameter 2.77 µm (without TCE), 3.07 µm with 0.5% and 3.23 µm with 1.0% TCE. Rheometry (flow) showed pseudoplastic behavior with minimal thixotropy for both systems. TCE could be released from emulsions containing 1.0% and 0.5% TCE in a controlled manner for 16 and 23 h, respectively. The emulsions allowed good retention of T...

BACKGROUND Agrobacterium sp. IFO 13140 cells were immobilized on a loofa sponge and used to produce curdlan over five successive cycles. The interaction between microbial cells and the loofa sponge as well as the produced curdlan were characterized by Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectrometry. The purity of the curdlan was also evaluated. The storage stability of the immobilized cells was assessed and the produced curdlan was used in a functional yogurt formulation. RESULTS The average curdlan production by immobilized cells was 17.84 g L−1. The presence of the microorganism in the sponge was confirmed and did not cause alterations in the matrix, and the chemical structure of the curdlan was the same as that of commercial curdlan. The purity of both was similar. The immobilized cells remained active after 300 days of storage at −18 °C. The use of the produced curdlan in a functional yogurt resulted in a product with lower syneresis. CONCLUSION A large number of cells physically adhered to the surface of loofa sponge fibers, and its use as an immobilization matrix to produce curdlan was effective. The use of the produced curdlan in yogurt allowed the development of a more stable product. © 2015 Society of Chemical Industry

The pressure ulcer healing is a complex process and difficult to be achieved. Insulin is known to promote wound healing, and when complexed with cyclodextrin presents improved solubility, stability and biological activity. Complexation of insulin with hydroxypropyl-beta-cyclodextrin (HPβCD) was performed in this work through the coprecipitation method, providing the inclusion complex (HPβCD–I). The spectroscopic techniques used to analyze the complex were H 1 NMR, FT-Raman and FT-IR/ATR. A gel containing the HPβCD–I complex was prepared and a clinical study was conducted in patients with pressure ulcers. The spectroscopic techniques allowed to confirm the complex formation through the inclusion of aromatic amino acids, such as phenylalanine present in the HPβCD cavity. Data obtained from the FT-Raman and FT-IR/ATR techniques, combined with the H 1 NMR results, showed the effectiveness of these techniques in evaluating the inclusion complex of HPβCD with insulin. Clinical studies demonstrated tissue revitalization and a trend ( p = 0.06) for a significant difference between the healing effect of the control gel and that with HPβCD–I complex. The creation of the gel prepared with insulin and HPβCD–I complex and its use in patients with pressure ulcers appears to be promising in wound healing and its possible use in hospital care.

Oxidative stress is an important factor modulating skin alterations. Melochia arenosa Benth. (Malvaceae) is a Brazilian plant with antimicrobial activity and antioxidant potential.The objective of this study is to develop a topical formulation containing antioxidant phenolic-rich extract of M. arenosa and to evaluate its skin permeation profile.Response surface methodology was used to maximize the total phenolic (TP) content of the extract and its antioxidant activity was evaluated by 2,2-diphenyl-1-picryl-hydrazyl (DPPH), 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and respiratory burst methods. An emulsion containing 1% optimized extract (OE) was developed and employed photoacoustic spectroscopy (PAS) for the determination of its skin permeation profile. The morphology of the skin was studied in histological sections stained with hematoxylin-eosin.The optimum conditions predicted for the major extractive efficiency of the phenolics with 100% ethanol led extraction time 101 h and plant:solvent proportion 1:13.5 (w/v). OE presented TP = 724.6 ± 8.2 mg GAE/g extract and scavenging capacity of DPPH (IC50 value = 11.43 ± 0.14 µg/mL) and ABTS radicals (IC50 value = 35.42 ± 0.48 µg/mL). The production of ROS by neutrophils after stimulation with phorbol miristate acetate was lower when the OE was present in the reaction medium, endorsing its high antioxidant capacity. The data obtained by PAS indicated that the OE present in the emulsion has permeated and was distributed in the whole skin. No histopathological alterations were observed in the histological analysis.The formulation developed is a promising tool for skin care and could prevent the damage caused by oxidative stress.

The relationship between emission tunability and the local environment of europium ions in OH−-free calcium aluminosilicate glasses was investigated, focusing on the development of devices for artificial lighting. Significant conversion of Eu3+ to Eu2+ was obtained by means of melting the glasses under a vacuum atmosphere and controlling the silica content, resulting in broad, intense, and tunable luminescence ranging from blue to red. Electron spin resonance and X-ray absorption near edge structure measurements enabled correlation of the luminescence behavior of the material with the Eu2+/Eu3+ concentration ratio and changes in the surrounding ions' crystal field. The coordinates of the CIE 1931 chromaticity diagram were calculated from the spectra, and the contour maps showed that the light emitted from Eu2+ presented broad bands and enhanced color tuning, ranging from reddish-orange to blue. The results showed that these Eu doped glasses can be used for tunable white lighting by combining matrix composition and the adjustment of the pumping wavelength.

To investigate the relationship between physicochemical interactions of resin luting cements with dentine and retention of fibre posts in root canals.Retention of fibre posts (RelyX Fiber Post) was assessed by the pull-out method. The diffusion zone of the cements and their chemical interaction with dentine were estimated by micro-Raman spectroscopy. Resin luting cements employing etch-and-rinse (Rely X Ultimate and Variolink II), self-etch (Rely X Ultimate and Panavia F2.0), or self-adhesive (RelyX Unicem 2) modes were investigated. Data were analyzed by analysis of variance followed by Tukey HSD tests.The retention of the fibre posts decreased in the following order: RelyX Ultimate, etch-and-rinse modeRelyX Unicem 2≥RelyX Ultimate, self-etch mode≥Panavia F2.0≥Variolink II (p0.05). One of the etch-and-rinse mode cements presented the deepest diffusion zone, while the other, along with the self-adhesive cement, produced the shallowest zone. Cements used in the self-etch mode showed intermediary diffusion into dentine (p0.05). All resin luting cements showed some degree of chemical interaction with dentine, the highest recorded for RelyX Ultimate used in the etch-and-rinse mode and the lowest for Panavia F2.0 (p0.05). The retention of fibre posts in the root canal could be attributed neither to the mode of interaction of the luting cements with dentine nor to their ability to diffuse into dentine.Chemical interaction between the resin luting cement and the dentine paired with adequate post pretreatment contribute positively to the retention of fibre posts.

Hypericin (Hyp) is a natural photoactive pigment utilized in the treatment of different types of cancer and antimicrobial inactivation using photodynamic therapy (PDT). Hyp is poorly soluble in water leading to problems of administration, getting close contact with the site, and bio-availability. Therefore, this study aimed to develop bioadhesive thermoresponsive system containing Hyp for local PDT. Carbomer 934P, poloxamer 407, and Hyp were used to prepare the thermoresponsive bioadhesive formulations. They were characterized for sol-gel transition temperature, mechanical, mucoadhesive, rheological (continuous flow and oscillatory) and dielectric properties, syringeability, in vitro Hyp release kinetics, ex vivo permeability, and photodynamic activity. The formulations displayed suitable gelation temperature and rheological characteristics. The compressional, mechanical and mucoadhesive properties, as well the syringeability showed the easiness of administration and the permanence of the system adhered to the mucosa or skin. The dielectric analysis helped to understand the Hyp availability, and its release presented an anomalous behavior. The system did not permeate the pig skin nor rat intestine and showed good biological photodynamic activity. Therefore, data obtained from the bioadhesive system indicate a potentially useful role as a platform for local hypericin delivery in PDT, suggesting it is worthy of in vivo evaluation.

Previous works have showed that calcium aluminosilicate (CAS) glasses, when prepared under vacuum conditions, are good candidates for solid state laser medium hosts and optical devices due to their appropriated thermal, optical and mechanical properties. These promising results led us to investigate the thermo-optical properties and emission spectra as a function of temperature in Nd3+ doped CAS glasses. Temperature changes in optical systems can cause structural modifications to the host, as well as other effects, such as emission quenching, or self-focalization. In this work, two series of CAS glasses, doped up to 5 wt.% Nd2O3, were prepared and characterized. Measurements of thermal coefficient of optical path length (dS/dT) and emission were performed on both series of Nd3+ doped CAS. In addition, measurements of optical absorption coefficient and emission lifetime were carried out. The results are discussed in terms of temperature dependence of these properties and Nd2O3 content. Comparisons with other glasses, such as LSCAS (low-silica calcium aluminosilicate) are also presented.

Fusarium is an emerging pathogen with high levels of morbidity and mortality. A significant tissue response is observed in infected patients, and the condition has been associated with the production of toxic metabolites. The aim of the present study was to identify a major fraction of crude metabolic extract of Fusarium oxysporum and investigate its effects on the skin of healthy rats. Fraction F1 was obtained from the cultivation of F. oxysporum in Czapek–Dox. In the treatment groups, fraction F1 (0.05 mg/ ml) was injected intradermally, while (50 µl) 0.9% of saline solution was injected in the control groups. The animals were killed 3, 6, 12, and 24 h after inoculation. The skin was fixed for inclusion in paraffin to obtain histological sections and stained with hematoxylin and eosin, Sirius red, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling. Samples were analyzed using Fourier transform Raman spectroscopy. The tissue reactions were classified and compared over time and by treatment. In the treatment group, inflammatory reaction peaked at 6 h, being classified as moderate, with infiltrate composed mainly of neutrophils. terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining was negative. The area occupied by types I and III collagen in the treatment group increased over time. There was a change in the area occupied by amide I and the ratios of the –CH2 and –CH3 molecules. It can be argued that the fraction F1 contains elements that contribute to the invasion of Fusarium in the skin, destructurizing the organization of the extracellular matrix. Copyright © 2014 John Wiley & Sons, Ltd.

Photophysics processes are ubiquitous in nature and difficult to be quantitatively characterized by conventional spectroscopy. Alternatively, pump-probe methods have been widely applied to study these complex processes. In this context, the thermal lens technique is a precise spectroscopic tool for material characterization and presents a wide range of applications in chemical analysis. Here, we present an all numerical approach to analyze the dynamics of photophysics processes and to identify the role of individual contributions of photoreaction and mass diffusion in the thermal lens experiments. The results are essential for a proper understanding of the dominant physical mechanisms in laser-induced photodegradation, which allow precise data analysis of the effects in photosensitive fluids.

We propose a combined thermal lens and thermal mirror method as concurrent photothermal techniques for the physical characterization of polymers. This combined method is used to investigate polymers as a function of temperature from room temperature up to 170 °C. The method permits a direct determination of thermal diffusivity and thermal conductivity. Additional measurements of specific heat, linear thermal expansion, and temperature-dependent optical path change are also performed. A complete set of thermal, optical, and mechanical properties of polycarbonate and poly (methyl methacrylate) samples are obtained. Methods presented here can be useful for in situ characterization of semitransparent materials, where fast and non-contacting measurements are required.

Objective To evaluate the color match of different composite resins relative to Vitapan Classical shade guide tab and their respective manufacturers' shade guide tabs as a function of time and storage. Materials and Methods Three enamel shade A2 composite resins were used to fabricate 36 disk-shaped polymerized specimens (12 each), allocated into 2 groups of 6 and stored dry (GD) and in artificial saliva (GS). CIELAB coordinates from shade tabs and resin specimens immediately after polymerization (t0), and 24 hours (t1), 7 (t7), 14 (t14) and 21 (t21) days after polymerization were captured using a colorimeter. Color difference (ΔE00) between composite specimens and the reference tabs was calculated using the CIEDE2000 formula. The results were analyzed with repeated measures ANOVA, Tukey's HDS post-hoc test, and Student t test (p ≤ 0.05). Results Color of the three tested composites relative to Vita and their respective tabs significantly changed as a function of time until t14; however, between t14 and t21, no significant differences were found. No differences in color were found relative to storage at t14 and t21. ΔE00 values of specimens at t14 were significantly higher relative to their respective tabs than to Vitapan tab. Conclusions For all brands color changed up to day 14, when it stabilized, regardless of whether composite specimens had been stored in artificial saliva or simply in a box. Vitapan tab presented a better color match than the manufacturers' tabs. Clinical Significance The results found in this study demonstrated that the Vitapan Classical shade guide tab A2 provided a better color match than the respective shade guide tabs A2 supplied by the composite manufacturers. If custom shade tabs are to be made, however, they could be kept in a box and used as shade references from 14 days after being fabricated, when color stabilizes.

Curcumin was complexed with β-CD using co-precipitation, freeze-drying and solvent evaporation methods. Co-precipitation enabled complex formation, as indicated by the FT-IR and FT-Raman techniques via the shifts in the peaks that were assigned to the aromatic rings of curcumin. In addition, photoacoustic spectroscopy and X-ray diffraction, with the disappearance of the band related to aromatic rings, by Gaussian fitting, and modifications in the spectral lines, respectively, also suggested complex formation. The possible complexation had an efficiency of 74% and increased the solubility of the pure colourant 31-fold. Curcumin–β-CD complex exhibited a sunlight stability 18% higher than the pure colourant. This material was stable to pH variations and storage at −15 and 4°C. With an isothermal heating at 100 and 150°C for 2h, the material exhibited a colour retention of approximately 99%. The application of curcumin–β-CD complex in vanilla ice creams intensified the colour of the products and produced a great sensorial acceptance.

Temperature coefficients of the refractive index ( $$\mathrm{d}n/\mathrm{d}T$$ ) in the $$25\,^{\circ }\mathrm{C}$$ to $$35\,^{\circ }\mathrm{C}$$ temperature interval for hydrocarbon mixtures containing as many as 14 compounds were investigated in this work. The measured $$-\mathrm{d}n/\mathrm{d}T$$ of the mixtures were compared with calculations based on the values for each compound and their concentrations. Differences of about 1 % between measured and calculated values were observed for all mixtures. The additivity of $$-\mathrm{d}n/\mathrm{d}T$$ for these hydrocarbons enables preparation of surrogate fuels that are formulated to have properties like those of specific diesel fuels.

Pure and Co-doped ZnO nanoparticles were synthesized with different cobalt levels (1–10 mol%) via adapted sol–gel method using water as solvent and characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy and photoacoustic absorption spectroscopy. The results showed that all the samples have hexagonal wurtzite structure, with no evidence of any secondary phases until 10 mol% of the dopant. The average crystallite size of the samples was in the range of 25–50 nm, do not showing significant differences with the increase of the dopant level. However, the band gap energy of the nanoparticles decreases from 2.98 eV (pure ZnO) to 1.95 eV (10 mol% of Co). The photocatalytic activity of the samples was evaluated on the removal of methylene blue under visible light irradiation, which revealed an efficiency reduction by Co-doping ZnO. The antibacterial property was carried out indicating activity of the prepared samples against gram-positive bacteria.

In this letter, we prepared and studied the plasmon, fluorescence and optical limiting properties of silver ion-exchanged glasses followed by an external thermal treatment for clusterization inside the glass matrix. TEM (Transmission electron microscopy) studies of the prepared samples provides information about the size of the nanoclusters, their size enhancement after TA (Thermal annealing) and supports the SPR band shape variations from the UV–Vis. absorption studies. Enhancement in fluorescence and optical-limiting (with excitation near to resonant value of the SPR) is ascribed to the amplified local field after metal nanocluster growth by thermal annealing.

Cyclodextrin glycosyltransferase (CGTase) catalyses the degradation of starch, producing α-, β-, and γ-cyclodextrins (CDs). Immobilized cells offer several advantages, such as their prolonged and repeated use, ease separation from the fermentation medium, and reduced risk of contamination. The biosynthesis of CGTase and β-CD was optimized by immobilization of Bacillus firmus strain 37 and Bacillus sphaericus strain 41 cells on a loofa sponge. Both microorganisms produced significant levels of CGTase for three consecutive cycles (94.2 U/mL on average), increased the relative formation of the β-CD, and inhibited the formation of other CDs. The crystallization of the CD produced by both bacterial strains, when corn starch was used as the substrate, resulted in a 64% recovery of β-CD. The purity of the β-CD was 89.5% when maltodextrin was used as the substrate for B. firmus strain 37. The Tilden–Hudson technique was used as a simple, inexpensive, and efficient method for monitoring the continuous production of CDs using immobilized cells. The innovative use of the Fourier Transform Infrared Spectroscopy technique by means of the Attenuated Total Reflectance method suggested that the interaction between the B. sphaericus strain 41 cells and the loofa sponge occurred by natural adsorption.

A theoretical model for a time-resolved photothermal mirror technique using pulsed-laser excitation was developed for low absorption samples. Analytical solutions to the temperature and thermoelastic deformation equations are found for three characteristic pulse profiles and are compared to finite element analysis methods results for finite samples. An analytical expression for the intensity of the center of a continuous probe laser at the detector plane is derived using the Fresnel diffraction theory, which allows modeling of experimental results. Experiments are performed in optical glasses, and the models are fitted to the data. The parameters of the fit are in good agreement with previous literature data for absorption, thermal diffusion, and thermal expansion of the materials tested. The combined modeling and experimental techniques are shown to be useful for quantitative determination of the physical properties of low absorption homogeneous linear elastic material samples.

Erbium doped tellurite glasses (TeO 2 + Li 2 O + TiO 2 ) were prepared by conventional melt-quenching method to study the influence of the Er 3+ concentration on the luminescence quantum efficiency ( η ) at 1.5 μm. Absorption and luminescence data were used to characterize the samples, and the η parameter was measured using the well-known thermal lens spectroscopy. For low Er 3+ concentration, the measured values are around 76%, and the concentration behavior of η shows Er–Er and Er–OH − interactions, which agreed with the measured lifetime values.

The aim of this work is to investigate the photoprotection activity and toxicity level of formulations containing the extract and its fractions obtained from leaves of Arrabidaea chica. The ex vivo percutaneous penetration of the extract was evaluated using the photoacoustic spectroscopy technique. The formulation presented optical absorption in the ultraviolet region, including UVA and UVB. This formulation was obtained without adding inorganic UV filters, as is frequently used in commercial sunscreens. The results showed a penetration rate similar to those of commercial sunscreens with its presence on the skin surface at least 180 min after the application. This formulation presented no toxic effects evaluated using hematological, biochemical, and histological assays. The results suggest that the formulation from the leaves of A. chica provides substantial protection against UVA + UVB radiation with a possible advantage of being natural and free of inorganic compounds compared with the majority of available commercial sunscreens.

In this work, the influence of the composition on the thermal and thermo-optical properties and luminescence of europium-doped calcium aluminosilicate glasses is investigated. High purity reagents were used to prepare samples with nominal compositions: $$2.5\hbox {Eu}_{2}\hbox {O}_{3},\,4.1\hbox {MgO},\,(7 + x)\hbox {SiO}_{2},\,(47.4 - x/2)\hbox {CaO},\,\hbox {and} (39 - x/2)\hbox {Al}_{2}\hbox {O}_{3},\,x = (0, 22, 27, 32, 37, 42,\,\hbox {and}\,47)\,(\hbox {in mass}\%)$$ . The ratio CaO/ Al $$_{2}$$ O $$_{3}$$ was kept at 1.2. At room temperature, measurements of the specific heat, mass density, temperature coefficient of the optical path length, and refractive index were performed. Two-beam thermal lens spectroscopy in the mismatch mode was used to determine the absolute values of the thermal diffusivity at room temperature. Using the thermal lens signal, the rate of heat generated by the nonradiative process was estimated, which showed a large decrease with increasing silica content. The decrease of this parameter can be related to the increase of the luminescence efficiency, which agrees with the results of luminescence spectroscopy. These results suggest an increase in the luminescence efficiency of europium-doped calcium aluminosilicate glasses at increments of increasing silica content.

This study evaluated physical, chemical and morphological changes in lungs of mice infected with Paracoccidioides brasiliensis. The animals were inoculated with 0.1 mL of fungal suspension of the P. brasiliensis 18 isolate and were euthanized 1, 2, 4 and 8 weeks after inoculation. The upper left lobe of the lung was isolated, fixed and processed for paraffin embedding. The sections were stained with H&E for histopathological study, with Gomori-Grocott to locate and identify the fungus, and with TUNEL immunostaining to detect the occurrence of programmed cell death. The lower and middle right lobes were analyzed by Fourier Transform Infrared Photoacoustic Spectrocopy (FTIR-PAS) to investigate physical and chemical features of the infected lungs. The results showed that lungs infected by P. brasiliensis underwent structural changes that varied according to the time period analyzed, and that changes in the absorption bands of different chemical groups resulted from these morphological changes. The results suggest that the combination of FTIR-PAS spectroscopy with morphological evaluation is an effective procedure for the study of paracoccidioidomycosis, one of the most important systemic mycoses that can damage the lung architecture and consequently impair the respiratory function.

The aim of this study was to investigate the diffusion dynamics of 25% hydrogen peroxide (H2O2) through enamel-dentin layers and to correlate it with dentin’s structural alterations. Micro-Raman Spectroscopy (MRS) and Fourier Transform Infrared Photoacoustic Spectroscopy (FTIR-PAS) were used to measure the spectra of specimens before and during the bleaching procedure. H2O2 was applied to the outer surface of human enamel specimens for 60 minutes. MRS measurements were performed on the inner surface of enamel or on the subsurface dentin. In addition, H2O2 diffusion dynamics from outer enamel to dentin, passing through the dentin-enamel junction (DEJ) was obtained with Raman transverse scans. FTIR-PAS spectra were collected on the outer dentin. MRS findings revealed that H2O2 (O-O stretching µ-Raman band) crossed enamel, had a more marked concentration at DEJ, and accumulated in dentin. FTIR-PAS analysis showed that H2O2 modified dentin’s organic compounds, observed by the decrease in amides I, II, and III absorption band intensities. In conclusion, H2O2 penetration was demonstrated to be not merely a physical passage through enamel interprismatic spaces into the dentinal tubules. H2O2 diffusion dynamics presented a concentration gradient determined by the chemical affinity of the H2O2 with each specific dental tissue.

The Thermal mirror technique relies on measuring laser-induced nanoscale surface deformation of a solid sample. The amplitude of the effect is directly dependent on the optical absorption and linear thermal expansion coefficients, and the time evolution depends on the heat diffusion properties of the sample. Measurement of transient signals provide direct access to thermal, optical and mechanical properties of the material. The theoretical models describing this effect can be formulated for very low optical absorbing and for absorbing materials. In addition, the theories describing the effect apply for semi-infinite and finite samples. In this work, we apply the Thermal mirror technique to measure physical properties of optical glasses. The semi-infinite and finite models are used to investigate very low optical absorbing glasses. The thickness limit for which the semi-infinite model retrieves the correct values of the thermal diffusivity and amplitude of the transient is obtained using the finite description. This procedure is also employed on absorbing glasses, and the semi-infinite Beer–Lambert law model is used to analyze the experimental data. The experimental data show the need to use the finite model for samples with very low bulk absorption coefficients and thicknesses L L > 1.0 mm in this case. In addition, the physical properties of the samples were calculated and absolute values derived.

Stability of potassium norbixinate and curcumin by microencapsulation with maltodextrin DE20 and freeze-drying was evaluated as a function of exposition to light, air, different pH, water solubility, and in food applications. The best results were obtained with microencapsulated potassium norbixinate 1:20, which, when vacuum-packed and in the presence of natural light, showed color retention of 78%, while microencapsulated curcumin 1:20 showed color retention of 71%. Differential scanning calorimetry and thermogravimetry provided an indication of interaction between colorants and maltodextrin. Photoacoustic spectroscopy (PAS) showed that free and microencapsulated colorants exhibited high rates of absorption throughout the measured spectral region. This work evidenced that the freeze-drying process is favorable for microencapsulation of curcumin by maltodextrin, providing improved solubility to the microencapsulated colorant. Both microencapsulated colorants showed relevant results for use in a wide range of pH and food applications. The PAS technique was useful for the evaluation of the stability of free and microencapsulated colorants.

Ce:Y 3 Al 5 O 12 and Eu:Y 3 Al 5 O 12 ceramics were obtained by combining high-energy ball milling and inert-gas flow sintering. The photoluminescence properties of Ce:Y 3 Al 5 O 12 ceramics were identical to those reported for Ce:Y 3 Al 5 O 12 single crystals, while the Eu:Y 3 Al 5 O 12 luminescence spectra were attributed to a larger concentration of Eu 2+ in relation to Eu 3+ ions as a direct consequence of the synthesis protocol. The Eu:Y 3 Al 5 O 12 photoluminescence emission and excitation spectra are very similar to those of Ce:Y 3 Al 5 O 12 , attesting the feasibility for applying Eu 2+ :Y 3 Al 5 O 12 ceramics as white-light phosphors.

Background Photodynamic inactivation of microorganisms is based on a photosensitizing substance which, in the presence of light and molecular oxygen, produces singlet oxygen, a toxic agent to microorganisms and tumor cells. This study aimed to evaluate singlet oxygen quantum yield of erythrosine solutions illuminated with a halogen light source in comparison to a LED array (control), and the photodynamic effect of erythrosine dye in association with the halogen light source on Streptococcus mutans . Methods Singlet oxygen quantum yield of erythrosine solutions was quantified using uric acid as a chemical-probe in an aqueous solution. The in vitro effect of the photodynamic antimicrobial activity of erythrosine in association with the halogen photopolimerizing light on Streptococcus mutans (UA 159) was assessed during one minute. Bacterial cultures treated with erythrosine alone served as negative control. Results Singlet oxygen with 24% and 2.8% degradation of uric acid in one minute and a quantum yield of 0.59 and 0.63 was obtained for the erythrosine samples illuminated with the halogen light and the LED array, respectively. The bacterial cultures with erythrosine illuminated with the halogen light presented a decreased number of CFU mL −1 in comparison with the negative control, with minimal inhibitory concentrations between 0.312 and 0.156 mg mL −1 . Conclusions The photodynamic response of erythrosine induced by the halogen light was capable of killing S. mutans. Clinical trials should be conducted to better ascertain the use of erythrosine in association with halogen light source for the treatment of dental caries.

From initial calcium aluminosilicate glass, transparent glass-ceramics have been successfully synthesized under simultaneous high pressure and temperature (SHPT). Possible homogeneous volumetric crystallization of this glassy system, which was not achieved previously by means of conventional heat treatment, has been put in evidence with a SHPT procedure. Structural, mechanical, and optical properties of glass and glass-ceramic obtained were investigated. Raman spectroscopy and X-ray diffraction allowed to identify two main crystalline phases: merwinite [Ca3Mg(SiO4)2] and diopside [CaMgSi2O6]. A Raman scanning profile showed that the formation of merwinite is quite homogeneous over the bulk sample. However, the sample surface also contains significant diopside crystals. Instrumented Berkovich nanoindentation was applied to determine the effect of SHPT on hardness from glass to glass-ceramic. For Eu-doped samples, the broadband emission due to 4f65d1 → 4f7 transition of Eu2+ was studied in both host systems. Additionally, the 5D0 → 7FJ transition of Eu3+ was used as an environment probe in the pristine glass and the glass-ceramic.

In situ micro-Raman spectroscopy was used to investigate the structural evolution of OH(-)-free calcium aluminosilicate glasses, under high pressure and at room temperature. Evaluation was made of the role of the SiO2 concentration in percalcic join systems, for Al/(Al + Si) in the approximate range from 0.9 to 0.2. Under high pressure, the intensity of the main band related to the bending mode of bridging oxygen ([Formula: see text][T-O-T], where T = Si or Al) decreased gradually, suggesting that the bonds were severely altered or even destroyed. In Si-rich glasses, compression induced a transformation of Q (n) species to Q (n-1). In the case of Al-rich glass, the Al in the smallest Q (n) units evolved from tetrahedral to higher-coordinated Al (([5])Al and ([6])Al). Permanent structural changes were observed in samples recovered from the highest pressure of around 15 GPa and, particularly for Si-rich samples, the recovered structure showed an increase of three-membered rings in the Si/Al tetrahedral network.

Eu 3+ and Eu 2+ co-doped calcium aluminosilicate glass–ceramics have been prepared by devitrification of calcium aluminosilicate glass using heat-treatment. Control of crystallization in the glass–ceramics was studied by X-ray diffraction (XRD) and Raman spectroscopy. The results showed that crystalline phases in glass–ceramic belong to the family of melilite Ca 2 Mg 0.25 Al 1.5 Si 1.25 O 7 as the major phase and anorthite CaAl 2 Si 2 O 8 as the minor phase. Luminescent properties were investigated by emission; lifetime and the color points were calculated. Emission spectra showed that Eu 2+ entered into the crystalline phase in a two steps mechanism: first as Eu 3+ which is then reduced to Eu 2+ . This incorporation in the crystal enhanced Eu 2+ emission with increasing time of heat-treatment and therefore crystallization.

Temperature coefficients of the refractive index (dn/dT) for nine hydrocarbons and two sets of binary mixtures were investigated in this work. The measured −dn/dT values for the pure hydrocarbons were found to be inversely proportional to their molar volumes (Vm) and molecular weights (M). Experimental data for binary mixtures show that −dn/dT varies linearly with volume and mass fractions, consistent with theory derived from the linear relationships of −dn/dT with 1/Vm and 1/M for individual hydrocarbons. This study should aid the interpretation of the observed correlations of dn/dT with physical and combustion properties of diesel fuels.

We have studied the influence of SiO2 content on the spectroscopic properties and laser emission efficiency of Yb3+-Er3+ co-doped calcium aluminosilicate glasses. An increase in SiO2 content resulted in higher phonon energy, which reduced the up-conversion emission, enhanced the energy transfer efficiency up to 70 % from Yb3+ to Er3+, and enhanced the optical quality. All these results led to an increase from 20 to 30 % in the laser emission efficiency.

In this paper, we report results concerning tunable light emission and color temperature in cerium-doped low-silica-calcium-alumino-silicate (LSCAS) glass for smart white-light devices. Spectroscopic results, analyzed using the CIE 1931 x – y chromatic diagram, show that this glass presents two broad emission bands centered at 475 and 540 nm, whose intensities can be tuned by the excitation wavelength. Moreover, the same emission can be achieved from a color temperature range from 3200 to 10,000 K, with a color-rendering index (CRI) of around 75% obtained by changing the optical path length of the sample. Our new phosphor LSCAS glass, which is a unique system that exhibits tunable yellow emission, combines all qualities for white-light devices.

The aim of this study was to develop a nanostructured Nb 2 O 5 –natural hydroxyapatite bulk composite to serve as an alternative biocompatible bulk material for implants. A set of samples of hydroxyapatite from fish bones with different concentrations of Nb 2 O 5 were designed. They were prepared through a milling process, compacted under different pressures (350, 450, 550 and 650 MPa) and sintered in air atmosphere at 1000 °C for 1 h. The results revealed that the prepared composites presented strong interactions between the two elements and showed improvement in the sinterability with significant densification and microstructure changes, suggesting that they are promising for implants meant to replace bone tissues.

We have experimentally measured the temperature dependence of the thermophysical properties of Nd2O3 doped borate glasses using a combination of the time resolved thermal lens technique with optical interferometry, thermal relaxation calorimetry and photoluminescence methods. Thermal diffusivity, thermal conductivity, fluorescence quantum efficiency, linear thermal expansion coefficient and thermal coefficient of the electronic polarizability were determined. The results showed the ability of these techniques to perform measurements very close to the glass transition region providing the absolute values of the measured physical quantities and the glass transition temperatures. In conclusion, it was observed that thermal lens and optical interferometry are advantageous methods for measurements as a function of temperature especially when low temperature scanning rate is required.

The dermatophytes are filamentous fungi that cause cutaneous fungal infections because they use keratin as a nutrient source. For this study the antidermatophyte activity of the extracts and derivates from leaves of Piper regnellii was analyzed. From the dichloromethane extract (EBD) neolignans such as eupomatenoid-3 and eupomatenoid-5 were obtained, and it was submitted to fractionation to remove the green residue, designated as the chloroform fraction (FF). Extracts, chloroform fraction and compounds were tested against Trichophyton rubrum ATCC 28189 to determine the minimum inhibitory concentration (MIC). The chloroform fraction was incorporated to nail lacquer that was analyzed by photoacoustic spectroscopy, in vitro assay and scanning electronic microscopy. For antifungal activity in solid medium the dichloromethane extract and chloroform fraction were used. The compounds eupomatenoid-3 and eupomatenoid-5 were less active than the dichloromethane extract against T. rubrum. EBD and FF showed moderate activity in hyphal growth inhibition in solid medium and EBD did not link to ergosterol. Nail lacquer containing the chloroform fraction showed good penetration through the nail as determined by photoacoustic spectroscopy. From in vitro studies it was observed that nail lacquer concentrations above 20 mg/mL prevented the growth of fungi, but concentrations up to 2.5 inhibited the growth. Scanning electronic microscopy was used to confirm the in vitro nail lacquer activity results. The specie P. regnellii showed great antifungal activity against T. rubrum, and nail lacquer containing its chloroform fraction has great potential to treat onychomycosis caused by these microorganisms.

The aim of this study was to evaluate the removal of butter cholesterol through three complexation methods with beta-cyclodextrin (beta-CD): co-precipitation, kneading, and physical mixture. Photoacoustic spectroscopy (PAS) was used to evaluate the inclusion complex cholesterol in beta-CD. The co-precipitation method was the most appropriate for removal of butter cholesterol. The composition in fatty acids was not affected by the adopted process. The standardization of the extraction technique of butter cholesterol for its quantification was efficient. The comparison between three quantification methods, enzymatic, high-performance liquid chromatography, and gas chromatography, showed no significant differences. PAS allowed to evaluate the extraction of butter cholesterol, and showed that the amount of beta-CD used can be reduced. The results showed that the use of this technique opens new prospects to confirm the formation of the inclusion complex, the “guest-beta-CD”.

Photoacoustic spectroscopy (PAS) was applied as a method to quantify dyed food samples, and was compared with First Derivative Spectrophotometry (FDS). The dyes Brilliant Blue (B), Sunset Yellow (S) and Tartrazine (T), which are common food additives, were employed for the comparisons. Polyester-type Polyurethane (PU) foam was used for extraction of the dyes from a solution containing the food matrix. For the spectrophotometric determinations, the adsorbed dyes were recovered by using dimethylformamide. The PAS measurements were carried out directly on the PU foam. The PAS method showed greater sensitivity, with detection limits of 0.028 mg L(-1) and 0.086 mg L(-1) for S and T, respectively, in the S+T mixture, and of 0.012 mg L(-1) and 0.068 mg L(-1) for B and T, respectively, in the B+T mixture. The values of relative error obtained for all the dyes were small: approximately 0.3-3.6% for the spectrophotometer, and approximately 0.1-2.9% for the PAS method. The PAS technique can be applied to the determination of the selected dyes in commercial food products, with some advantages: it reduces the number of analysis steps, it is a "green" method with less chemical waste, a minimal sample amount is needed, and it is non-destructive.

A complete theoretical model is presented for the thermal mirror technique under top-hat laser excitation. Considering the attenuation of the top-hat excitation laser intensity along the thickness of a sample due to its optical absorption coefficient, we calculate the laser-induced temperature and surface deformation profiles. A simplified theoretical model for a high absorption sample is also developed. The center intensity of a probe beam reflected from the thermal mirror at a detector plane is derived. Numerical simulation shows that the thermal mirror under the top-hat laser excitation is as sensitive as that under Gaussian laser excitation. With top-hat laser excitation, the experimental results of thermo-physical properties of opaque samples are found to be well consistent with literature values, validating the theory.

The calcium aluminosilicate glass (CAS) is an important class of optical materials due to the many applications envisaged, including its use as active media for glass lasers. In order to study how Nd 2 O 3 doping affects the mechanical and the thermo-optical properties of CAS glass, two series of CAS glass, doped with Nd 2 O 3 up to 5 wt%, were prepared in a vacuum atmosphere. The rare earth changes the physical properties, and this influence of doping ion content is discussed for both the series of samples in terms of mechanical, thermal, and thermo-optical properties. The study analyzed hardness and elastic moduli, glass transition temperature, crystallization temperature, thermal diffusivity, specific heat, density, thermal conductivity, refractive index, and thermo-optical properties, like temperature coefficient of the optical path length (d S /d T ). The results presented provide information about the sample’s structure, and show that for Nd 2 O 3 concentration up to 5 wt% there were no significant changes in the glass host material.

The physical and chemical characteristics of silica based materials and doped with different metals (Ni, Co and Ru) synthesized by the sol–gel method were investigated. The used techniques were: temperature programmed reduction, thermogravimetric analysis, specific surface area measurements, X-ray diffraction and Photoacoustic Spectroscopy. After calcination, higher surface areas were obtained, with the larger value for Ru–SiO2 (550 m2/g), followed by Ni–SiO2 (337 m2/g) and Co–SiO2 (298 m2/g). For Ni–SiO2, the nickel oxide is present at the surface in two different forms. This also happens for the Co–SiO2 material, which showed two reduction peaks, probably attributed to the Co III ⇒ Co II and Co II ⇒ Co 0 reaction. However, for Ru–SiO2 only one peak reduction was observed. The X-ray diffraction data revealed the existence of an amorphous structure, while thermogravimetric analysis showed that the calcination procedure decomposes the organic residues adsorbed at the material surface.

ZSM-5 zeolites modified by iron incorporation through post-synthesis ion exchange and those synthesized with iron addition to the synthesis medium were compared in the reaction of liquid hydrocarbons production from ethanol. AA, TPR, FTIR, XRD, SEM, nitrogen adsorption and photoacoustic spectroscopy were used for the samples characterization. Acid leaching and ammonium exchange were tested for obtaining the acid form of the zeolite, with similar results, the major difference being a faster deactivation in the latter case. The best yield of liquid hydrocarbons was obtained with the samples with low iron content. The product distribution in both gaseous and liquid phases was independent of the way the zeolite was obtained or the iron was introduced, with major variations only with time (due to deactivation).

We consider nonlocal effects, obtained by incorporating fractional derivatives in the kinetic energy of a conventional Hamiltonian, to analyze physical properties of non-crystalline solids at very low temperature. By using thermal Green functions, we deduce some experimentally observable quantities such as the particle momentum distribution function, the particle energy distribution function, and the specific heat. The agreement between the results obtained for the specific heat and the experimental data suggests that the approach presented here may be useful as a phenomenological model to investigate thermal properties of non-crystalline solids at low temperature.

In this work we report on the use of the Thermal Lens method to verify the evolution of the thermal diffusivity of sunflower and soybean vegetable oils utilized in preparation of twenty five snacks portions. Our results show that the thermal diffusivity for sunflower oil does not change between 1 and 25 portions of fried snacks. By another hand, the soybean thermal diffusivity exhibits a little decrease for higher portion of fried snacks, indicating that for this oil the triglyceride level is reduced as a degradation process.

In this work, the thermal lens spectrometry was applied to measure the thermo-optical properties of Nd 2 O 3 -doped low silica calcium aluminosilicate glasses as a function of temperature, between 4.3 and 300 K. The thermal relaxation calorimetry was used to determine the specific heat, c p . The results showed a decrease of the thermal diffusivity of about one order of magnitude from 4.3 K up to 300 K, with a T −1 dependence in the interval between 20 and 70 K and a T −0.35 between 4.3 and 20 K. The fluorescence quantum efficiencies of the doped samples were calculated down to 50 K, showing a variation of the order of 12% and 25% for the samples with 0.6 and 1.04 mol% of Nd 2 O 3 , respectively. In addition, the temperature corresponding to the maximum in c p / T 3 , the so-called boson peak, was observed at about 17 K for the undoped sample and at lower temperatures for the doped glasses. In conclusion, our results showed the ability of the time resolved thermal lens to determine the thermo-optical properties of glasses at temperatures lower than 300 K, bringing new possibilities for experiments in a wide range of optical materials.

Fricke chemical dosimetry measurements of the absorbed dose of ionizing radiation depend on the quality and characteristics of the system that reads each dosimeter. The final accuracy is significantly dependent on the technique used for measuring the chemical concentration changes in the dosimeters. We have used a photoacoustic technique to detect the Fricke xylenol gel (FXG) optical absorbance. The FXG, a derivation of the aqueous Fricke dosimeter, is made more sensitive and stable with addition of gelatin (300 Bloom) and xylenol orange. The light intensity transmitted through an FXG sample before and after irradiation was measured with an acoustic detector. The incremental optical absorbance is directly proportional to the ionizing radiation absorbed dose. We present the optical absorbance measurements as a function of absorbed dose and of post-irradiation time. We apply our photoacoustic technique to determine absorbed dose profiles. The results show that the photoacoustic technique applied to FXG provides a new dosimetric system, as good as those already established using spectrophotometric techniques.

In the present work, the rear photoacoustic signal technique is used to determine thermal properties of human nails. The aging process of the human nail is analyzed through its thermal diffusivity and specific heat and using these results, thermal conductivity and thermal effusivity is determined. The study in vitro of this natural polymer showed a minimum for thermal properties to age about 20 years and an increase and possible saturation of them for ages over 50 years. The minimum value found for thermal diffusivity was close to 10 x 10 -4 cm 2 s -1 with saturation near 18 x 10 -4 cm2 s -1 . Thermal conductivity and effusivity presents the same behavior.

The origin of the broad maximum in the specific heat (c P) of glassy systems in the c P/T 3 representation, in correspondence with the boson peak, has been described from a semiclassical perspective. A new model, based in the Debye approximation, taking into account the anharmonic vibrations of correlated atoms, is proposed. The theoretical predictions are shown to be in good agreement with the experimental data obtained in several glass samples in the temperature range 2–80 K.

We induce nanometer-scale surface deformation by exploiting momentum conservation of the interaction between laser light and dielectric liquids. The effect of radiation force at the air-liquid interface is quantitatively assessed for fluids with different density, viscosity and surface tension. The imparted pressure on the liquids by continuous or pulsed laser light excitation is fully described by the Helmholtz electromagnetic force density.