Modeling hourly and daily fractions of UV, PAR and NIR to global solar radiation under various sky conditions at Botucatu, Brazil

In this analysis, using available hourly and daily radiometric data performed at Botucatu, Brazil, several empirical models relating ultraviolet (UV), photosynthetically active (PAR) and near infrared (NIR) solar global components with solar global radiation (G) are established. These models are developed and discussed through clearness index K(T) (ratio of the global-to-extraterrestrial solar radiation). Results obtained reveal that the proposed empirical models predict hourly and daily values accurately. Finally. the overall analysis carried Out demonstrates that the sky conditions are more important in developing correlation models between the UV component and the global solar radiation. The linear regression models derived to estimate PAR and NIR components may be obtained without sky condition considerations within a maximum variation of 8%. In the case of UV, not taking into consideration the sky condition may cause a discrepancy of up to 18% for hourly values and 15% for daily values. (C) 2008 Elsevier Ltd. All rights reserved.

The periodicity of the eta Carinae events

Extensive spectral observations of eta Carinae over the last cycle, and particularly around the 2003.5 low-excitation event, have been obtained. The variability of both narrow and broad lines, when combined with data taken from two earlier cycles, reveal a common and well-defined period. We have combined the cycle lengths derived from the many lines in the optical spectrum with those from broad-band X-rays, optical and near-infrared observations, and obtained a period length of P(pres) = 2022.7 +/- 1.3 d. Spectroscopic data collected during the last 60 yr yield an average period of P(avg) = 2020 +/- 4 d, consistent with the present-day period. The period cannot have changed by more than Delta P/P = 0.0007 since 1948. This confirms the previous claims of a true, stable periodicity, and gives strong support to the binary scenario. We have used the disappearance of the narrow component of He I 6678 to define the epoch of the Cycle 11 minimum, T(0) = JD 245 2819.8. The next event is predicted to occur on 2009 January 11 (+/- 2 d). The dates for the start of the minimum in other spectral features and broad-bands are very close to this date, and have well-determined time-delays from the He I epoch.

Multi-Conjugate Adaptive Optics VLT imaging of the distant old open cluster FSR 1415

We employ the recently installed near-infrared Multi-Conjugate Adaptive Optics demonstrator (MAD) to determine the basic properties of a newly identified, old and distant, Galactic open cluster (FSR 1415). The MAD facility remarkably approaches the diffraction limit, reaching a resolution of 0.07 arcsec (in K), that is also uniform in a field of similar to 1.8 arcmin in diameter. The MAD facility provides photometry that is 50 per cent complete at K similar to 19. This corresponds to about 2.5 mag below the cluster main-sequence turn-off. This high-quality data set allows us to derive an accurate heliocentric distance of 8.6 kpc, a metallicity close to solar and an age of similar to 2.5 Gyr. On the other hand, the deepness of the data allows us to reconstruct (completeness-corrected) mass functions (MFs) indicating a relatively massive cluster, with a flat core MF. The Very Large Telescope/MAD capabilities will therefore provide fundamental data for identifying/analysing other faint and distant open clusters in the Galaxy III and IV quadrants.

Global properties of `ordinary` early-type galaxies: photometry and spectroscopy of stars and globular clusters in NGC 4494

We present a comprehensive analysis of the spatial, kinematic and chemical properties of stars and globular clusters (GCs) in the `ordinary` elliptical galaxy NGC 4494 using data from the Keck and Subaru telescopes. We derive galaxy surface brightness and colour profiles out to large galactocentric radii. We compare the latter to metallicities derived using the near-infrared Calcium Triplet. We obtain stellar kinematics out to similar to 3.5 effective radii. The latter appear flattened or elongated beyond similar to 1.8 effective radii in contrast to the relatively round photometric isophotes. In fact, NGC 4494 may be a flattened galaxy, possibly even an S0, seen at an inclination of similar to 45 degrees. We publish a catalogue of 431 GC candidates brighter than i(0) = 24 based on the photometry, of which 109 are confirmed spectroscopically and 54 have measured spectroscopic metallicities. We also report the discovery of three spectroscopically confirmed ultra-compact dwarfs around NGC 4494 with measured metallicities of -0.4 less than or similar to [Fe/H] less than or similar to -0.3. Based on their properties, we conclude that they are simply bright GCs. The metal-poor GCs are found to be rotating with similar amplitude as the galaxy stars, while the metal-rich GCs show marginal rotation. We supplement our analysis with available literature data and results. Using model predictions of galaxy formation, and a suite of merger simulations, we find that many of the observational properties of NGC 4494 may be explained by formation in a relatively recent gas-rich major merger. Complete studies of individual galaxies incorporating a range of observational avenues and methods such as the one presented here will be an invaluable tool for constraining the fine details of galaxy formation models, especially at large galactocentric radii.

Selective Wrapping and Supramolecular Structures of Polyfluorene-Carbon Nanotube Hybrids

We report on the photophysical properties of single-walled carbon nanotube (SWNT) suspensions In toluene solutions of poly[9,9-dioctylfluorenyl-2,7-diyl](PFO). Steady-state and time-resolved photoluminescence spectroscopy in the near-infrared and visible spectral regions are used to study the interaction of the dispersed SWNTs with the wrapped polymer. Molecular dynamics simulations of the PFO-SWNT hybrids in toluene were carried out to evaluate the energetics of different wrapping geometries. The simulated fluorescence spectra in the visible region were obtained by the quantum chemical ZINDO-CI method, using a sampling of structures obtained from the dynamics trajectories. The tested schemes consider polymer chains aligned along the nanotube axis, where chirality has a minimal effect, or forming helical structures, where a preference for high chiral angles is evidenced. Moreover, toluene affects the polymer structure favoring the helical conformation. Simulations show that the most stable hybrid system is the PFO-wrapped (8,6) nanotube, in agreement with the experimentally observed selectivity.

Phase change and pyroelectricity in natural hemimorphite

The phase change of a natural hemimorphite sample from Minas Gerais (Brazil) was investigated by two X-ray diffraction (XRD) methods and by near-infrared reflectance spectroscopy. Applying successive thermal treatments, the crystal structure undergoes two orientation conversions. The first one occurs at about 550 degrees C, and it was revealed by the Laue method. Below 500 degrees C, the water molecules were partially expelled without changing the crystal structure. A fact that supports this statement is the sequential disappearance of the water bands at 1400 and 1900 nm by thermal treatment. The second conversion takes place below 939 degrees C. Moreover, at 972 degrees C a phase change to the willemite mineral (alpha-Zn(2)SiO(4)) has been observed. This last conversion was confirmed by the power XRD. In addition, natural hemimorphite displayed a high pyroelectricity, which is related both to the absence of inverse centre and to the presence of molecular water and hydroxyl groups in the crystal structure.

In vitro effect of low-level laser on odontoblast-like cells

The aim of this study was to evaluate the metabolism of odontoblast-like MDPC-23 cells subjected to direct LLL irradiation. The cells were seeded (20,000 cells/well) in 24-well plates and incubated for 24 hours at 37 degrees C. After this period, the culture medium (DMEM) was replaced by fresh DMEM supplemented with 2 or 5% (stress induction by nutritional deficit) or 10% fetal bovine serum (FBS). The cells were exposed to laser doses of 2, 4, 10, 15 and 25 J/cm(2) from a near infrared InGaAsP diode laser prototype (LASERTable; 780 +/- 3 nm, 40 mW). One control group (sham irradiation) was established for each experimental condition (laser dose x FBS supplementation). Three and 72 hours after the last irradiation, cells were analyzed with respect to metabolism, morphology, total protein expression and alkaline phosphatase (ALP) activity. Higher metabolism and total protein expression were observed 72 hours after the last irradiation at the doses of 15 and 25 J/cm(2) (Mann-Whitney; p<0.05). Higher ALP activity was obtained with 5% FBS when the cells were irradiated with doses of 2 and 10 J/cm(2). For the dose of 25 J/cm(2), the highest ALP activity was observed with 10% FBS. It was concluded that the LLLT parameters used in this study stimulated the metabolic activity of the MDPC-23 cells, especially at the doses of 15 and 25 J/cm(2).

Increased Viability of Odontoblast-Like Cells Subjected to Low-Level Laser Irradiation

Studies have shown that the increase of cell metabolism depends on the low level laser therapy (LLLT) parameters used to irradiate the cells. However, the optimal laser dose to up-regulate pulp cell activity remains unknown. Consequently, the aim of this study was to evaluate the metabolic response of odontoblast-like cells (MDPC-23) exposed to different LLLT doses. Cells at 20000 cells/cm(2) were seeded in 24-well plates using plain culture medium (DMEM) and were incubated in a humidified incubator with 5% CO(2) at 37 degrees C. After 24 h, the culture medium was replaced by fresh DMEM supplemented with 5% (stress by nutritional deficit) or 10% fetal bovine serum (FBS). The cells were exposed to different laser doses from a near infrared diode laser prototype designed to provide a uniform irradiation of the wells. The experimental groups were: G1: 1.5 J/cm(2) + 5% FBS; G2: 1.5 J/cm(2) + 10% FBS; G3: 5 J/cm(2) + 5% FBS; G4: 5 J/cm(2) + 10% FBS; G5: 19 J/cm(2) + 5% FBS; G6: 19 J/cm(2) + 10% FBS. LLLT was performed in 3 consecutive irradiation cycles with a 24-hour interval. Non-irradiated cells cultured in DMEM supplemented with either 5 or 10% FBS served as control groups. The analysis of the metabolic response was performed by the MTT assay 3 h after the last irradiation. G1 presented an increase in SDH enzyme activity and differed significantly (Mann-Whitney test, p < 0.05) from the other groups. Analysis by scanning electron microscopy showed normal cell morphology in all groups. Under the tested conditions, LLLT stimulated the metabolic activity of MDPC-23 cultured in DMEM supplemented with 5% FBS and exposed to a laser dose of 1.5 J/cm(2). These findings are relevant for further studies on the action of near infrared lasers on cells with odontoblast phenotype.

Effect of low-level laser irradiation on odontoblast-like cells

Low-level laser therapy (LLLT), also referred to as therapeutic laser, has been recommended for a wide array of clinical procedures, among which the treatment of dentinal hypersensitivity. However, the mechanism that guides this process remains unknown. Therefore, the objective of this study was to evaluate in vitro the effects of LLL irradiation on cell metabolism (MTT assay), alkaline phosphatase (ALP) expression and total protein synthesis. The expression of genes that encode for collagen type-1 (Col-1) and fibronectin (FN) was analyzed by RT-PCR. For such purposes, oclontoblast-like cell line (MDPC-23) was previously cultured in Petri dishes (15000 cells/cm(2)) and submitted to stress conditions during 12 h. Thereafter, 6 applications with a monochromatic near infrared radiation (GaAlAs) set at predetermined parameters were performed at 12-h intervals. Non-irradiated cells served as a control group. Neither the MTT values nor the total protein levels of the irradiated group differed significantly from those of the control group (Mann-Whitney test; p > 0.05). On the other hand, the irradiated cells showed a decrease in ALP activity (Mann-Whitney test; p < 0.05). RT-PCR results demonstrated a trend to a specific reduction in gene expression after cell irradiation, though not significant statistically (Mann-Whitney test; p > 0.05). It may be concluded that, under the tested conditions, the LLLT parameters used in the present study did not influence cell metabolism, but reduced slightly the expression of some specific proteins.

Thymine hydroperoxide as a potential source of singlet molecular oxygen in DNA

The decomposition of organic hydroperoxides into peroxyl radicals is a potential source of singlet molecular oxygen [O(2) ((1)Delta(g))] in biological systems. This study shows that 5-(hydroperoxymethyl)uracil (5-HPMU), a thymine hydroperoxide within DNA, reacts with metal ions or HOCl, generating O(2) ((1)Delta(g)). Spectroscopic evidence for generation of O(2) ((1)Delta(g)) was obtained by measuring (i) the bimolecular decay, (ii) the monomolecular decay, and (iii) the observation of D(2)O enhancement of O(2) ((1)Delta(g)) production and the quenching effect of NaN(3). Moreover, the presence of O(2) ((1)Delta(g)) was unequivocally demonstrated by the direct characterization of the near-infrared light emission. For the sake of comparison, O(2) ((1)Delta(g)) derived from the H(2)O(2)/HOCl system and from the thermolysis of the N,N`-di(2,3-dihydroxypropyl)-1,4-naphthalenedipropanamide endoperoxide was also monitored. More evidence of O(2) ((1)Delta(g)) generation was obtained by chemical trapping of O(2) ((1)Delta(g)) with anthracene-9,10-divinylsulfonate (AVS) and detection of the specific AVS endoperoxide by HPLC/MS/MS. The detection by HPLC/MS of 5-(hydroxymethyl)uracil and 5-formyluracil, two thymine oxidation products generated from the reaction of 5-HPMU and Ce(4+) ions, supports the Russell mechanism. These photoemission properties and chemical trapping clearly demonstrate that the decomposition of 5-HPMU generates O(2) ((1)Delta(g)) by the Russell mechanism and point to the involvement of O(2) ((1)Delta(g)) in thymidine hydroperoxide cytotoxicity. (C) 2009 Elsevier Inc. All rights reserved.

Protoporphyrin IX Nanoparticle Carrier: Preparation, Optical Properties, and Singlet Oxygen Generation

The present study is focused on developing a nanoparticle carrier for the photosensitizer protoporphyrin IX for use in photodynamic therapy. The entrapment of protoporphyrin IX (Pp IX) in silica spheres was achieved by modification of Pp IX molecules with an organosilane reagent. The immobilized drug preserved its optical properties and the capacity to generate singlet oxygen, which was detected by a direct method from its characteristic phosphorescence decay curve at near-infrared and by a chemical method using 1,3-diphenylisobenzofuran to trap singlet oxygen. The lifetime of singlet oxygen when a suspension of Pp IX-loaded particles in acetonitrile was excited at 532 nm was determined as 52 mu s, which is in good agreement with the value determined for methylene blue in acetonitrile solution under the same conditions. The Pp IX-loaded silica particles have an efficiency of singlet oxygen generation (eta Delta) higher than the quantum yield of free porphyrins. This high efficiency of singlet oxygen generation was attributed to changes on the monomer-dimer equilibrium after photosentisizer immobilization.

Singlet oxygen generation in the reaction centers of Rhodobacter sphaeroides

Singlet oxygen ((1)O(2)) generation in the reaction centers (RCs) of Rhodobacter sphaeroides wild type was characterized by luminescent emission in the near infrared region (time resolved transients and emission spectra) and quantified to have quantum yield of 0.03 +/- 0.005. (1)O(2) emission was measured as a function of temperature, ascorbate, urea and potassium ferricyanide concentrations and as a function of incubation time in H(2)O: D(2)O mixtures. (1)O(2) was shown to be affected by the RC dynamics and to originate from the reaction of molecular oxygen with two sources of triplets: photoactive dimer formed by singlet-triplet mixing and bacteriopheophytin formed by direct photoexcitation and intersystem crossing.

Polymethine cyanine dyes in beta-cyclodextrin solution: multiple equilibria and chemical oxidation

Absorption and fluorescence spectroscopy, electrochemical techniques, and semiempirical calculations were employed to characterize the multiple complexation equilibria between two polymethine cyanine dyes (IR-786 and Indocyanine green-ICG, 5) and beta-cyclodextrin (beta-CD, L), as well as the chemical reactivity of the complexed and uncomplexed species against the oxidizing agents hypochlorite (HC) and hydrogen peroxide (HP). IR-786 dimerization is favored with the increase in beta-CD concentration in the form of (SL)(2) complexes. In the case of ICG, free dimers (D) and SL complexes are favored. Both IR-786 and ICG react and discolor in the presence of HC and HP. For IR-786, the reaction with HP and HC proceeds with observed rate constants of 10(-3) and 0.28 s(-1) and second-order rate constants (k(2)) of similar to 10(-3) and 10(4) M(-1) s(-1), respectively. The intermediate species observed in the bleaching reactions of IR-786 and ICG were shown, by cyclic voltammetry and VIS absorption, to result from one electron oxidation. IR-786 complexed with beta-CD is protected against bleaching in the presence of HP and HC by factors of 20 and 4, respectively. This protection was not observed in ICG complexes. Superdelocalizability profile of both dyes and frontier orbital analysis indicates that beta-CD does not protect ICG from oxidation by HP or HC, whereas the 2:2 IR-786/beta-Cd complex is able to avoid the oxidation of IR-786. We concluded that the decrease in the chemical reactivity of the dyes against oxidant agents in the presence of beta-CD is due to the formation of (SL)(2) complexes. Copyright (C) 2010 John Wiley & Sons, Ltd.

Structural Investigation of MFe(2)O(4) (M = Fe, Co) Magnetic Fluids

Ferrites of the type M(II)Fe(2)O(4) (M = Fe and Co) have been prepared by the traditional coprecipitation method. These ferrites were modified by the adsorption of fatty acids derived from soybean and castor oil and were then dispersed in cyclohexane, providing very stable magnetic fluids, readily usable in nonpolar media. The structural properties of the ferrites and modified ferrites as well as the magnetic fluids were characterized by XRD (X-ray powder diffraction), TEM (transmission electron microscopy), DRIFTS (diffusion reflectance infrared Fourier transform spectroscopy), FTMR (Fourier transform near-infrared), UV-vis, normal Raman spectroscopy, and surface-enhanced Raman scattering (SERS). XRD and TEM analysis have shown that the magnetic nanoparticles (nonmodified and modified) present diameters in the range of 10-15 nm. DRIFTS measurements have shown that the carboxylate groups of soybean and castor oil fatty acids adsorb on the ferrite surface, forming three different structures: a bridging bidentate, a bridging monodentate, and a bidentate chelate structure. The FTIR and Raman spectra of nonmodified Fe(3)O(4) and CoFe(2)O(4) nanoparticles have shown that the number of observed phonons is not compatible with the expected O(h)(7) symmetry, since IR-only active phonons were observed. in the Raman spectra and vice versa. SERS measurements of a CoFe(2)O(4) thin film on a SERS-active gold electrode at different applied potentials made possible the assignment of the signals near 550 and 630 cm(-1) to Co-O motions and the signals near 470 and 680 cm(-1) to Fe-O motions.

Influence of Reaction Conditions on Synthesis of PAni/MnO(2) Composites

An investigation of the parameters as aniline: MnO(2) and temperature on synthesis of polyaniline/MnO(2) composites was performed. The composites were chemically prepared in H(2)SO(4) media using different aniline: MnO(2) ratios at 0 degrees C. After the ratio optimization, the syntheses were performed at 20 degrees C. The polyaniline/MnO(2) composites were characterized by scanning electron microscopy (SEM), ultraviolet-visible, near infrared and infrared spectroscopic techniques. Composites obtained with a uniform, homogeneous and thicker coating of polyaniline films under oxide was considered as the best condition for synthesis.