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A conformal invariant QED-inspired model is solved for a general covariant linear gauge using the Dyson–Schwinger equations for the propagators assuming a pure vector like interaction. The leading corrections to the asymptotic solutions and the exponents, that characterize the corrections to each of the two fermion propagator functions, are computed as a function of the coupling and gauge fixing parameter ξ . For the scalar component of the fermion propagator our findings generalizes for linear covariant gauges previous results found in the literature and reproduce the outcome of the perturbative analysis of quenched QED in the Landau gauge. Our solution for the exponent associated with vector component of the fermion propagator is new and, in the weak coupling regime, agrees with the estimation based on the perturbative analysis of quenched QED. Of the two critical exponents describing the conformal limit of the vector interaction, one of them is, in QED, associated with the regime where chiral symmetry is broken dynamically, which demands one mass scale, namely the Miransky scaling. A second mass scale has to be introduced at larger coupling constants and is associated with a change on the nature of the fermion wave function. This provides one example, that it is possible to find two interwoven cycles in Quantum Field Theory, albeit in a truncated framework, as it is known in the quantum few-body problem in the limit of a zero-range interaction. [ABSTRACT FROM AUTHOR]

Several studies on cytogenetic characterisation of passion flowers are helpful to elucidate doubts about taxa relationships, delimitation and classification into more coherent groups based on karyomorphological data.Molecular and conventional cytogenetic techniques were applied to three Passiflora species with red flowers, P. coccinea, P. vitifolia and P. tholozanii, for species karyotype relationships. Additionally, for descriptive morphology, were used flowers, leaves and seeds.Results describe for the first time the karyomorphological and chromosome number (2n = 18) for P. tholozanii. anova was performed (P < 0.05) and statistical significance for average chromosome size (CV: 16.53%) between species. Genomic in situ hybridisation (GISH) proved relationships between P. coccinea and P. tholozanii, which suggests a common origin, however, we could not identify hybridisation between genomic probes from P. vitifolia in P. tholozanii chromosomes. Among the species analysed, P. tholozanii has great similarity in karyotypic and morphology to P. coccinea but not to P. vitifolia.We suggest the inclusion of P. tholozanii in the same subgenus and section as P. coccinea based on the similarity in karyomorphological and morphological traits between the species. Additionally, GISH might indicate a common or hybrid origin of P. tholozanii. [ABSTRACT FROM AUTHOR]

Focuses on a study which described the current-voltage characteristics of positive and negative polarity. Applications of corona discharge; Dependence of current on voltage; Evidence of an electronic component of the negative current.

The magnetoelectric materials have been being studied due to the scientific chalenges and the very promissing possibility of applications in electronic devices. BiFeO3 is room temperature single-phase multiferroic material. However there are some issues regarding conductivity and undesired parasitic phases that cause the experimentally reduced electrical polarization and low or no net magnetization in this material. In order to solve these questions we studied the effect of partial replacement of Bi3+ by Nd3+ in the Bi1-xNdxFe0.99Co0.01O3 compositions. X-ray diffraction patterns confirmed single phased rhombohedrally distorted perovskite structure in obtained ceramics. Scanning electron microscopy images reveal that the ceramic grains are almost irregular spheres with a 2 μm in diameter, and samples present equal porosity. With the increasing of the Nd3+ substitution the real part of the dielectric constant increased in almost 10 times but decreases the magnetization. As a consequence, the Bi1-xNdxFe0.99Co0.01O3 ceramics presented an induced magnetoelectric voltage and magnetodielectric effects. [ABSTRACT FROM AUTHOR]

The study of multiferroic crystalline materials is of great technological and academic interest due to the correlation between their ferroelectric and ferromagnetic properties. In this work, ferroic properties of Nd-modified (A-site substitution) BiFeO3(BNFO) compounds were studied. Ceramic compositions of Bi1-xNdxFeO3(x = 0.10 and 0.20) were obtained through a route that included high-energy ball milling, isostatic pressing (to obtain the ceramic shape) and sintering in air. The X-ray diffraction data showed that these compositions have a distorted perovskite structure, with relative densities reaching 93%. Dielectric measurements showed a frequency independent step-like relaxation for the Bi0.9Nd0.1FeO3composition and indicatives indications of thermally activated conduction processes for the Bi0.8Nd0.2FeO3composition. Magnetic studies showed a breakdown of the typical magnetic cycloidal structure of BiFeO3. [ABSTRACT FROM AUTHOR]

Context: Ethnozoological studies have shown that Spilotes pullatus Linn. (Colubridae: Ophidia), is associated with medicinal and magic-religious uses in Brazil. Objectives: This study was designed to determine the chemical composition of the oil extracted from the body fat of S. pullatus and to test its antimicrobial properties, alone and in association with aminoglycosides, against fungi and bacterial strains in concentrations ranging between 1024 and 0.5 µg/mL. Material and methods: The snakes were collected in the Chapada do Araripe, county of Crato, Ceará State, Brazil. The oil was extracted in a Soxhlet apparatus using hexane. The methyl esters of the fatty acids present in the samples were identified using GC-MS. The antimicrobial and drug modulatory activities of oil were tested by microdilution against fungal and bacterial strains. Results: The chemical composition of the fixed oils of S. pullatus identified 10 constituents representing 94.97% of the total sample. The percentages of saturated and unsaturated fatty acids were 33.59 and 61.38%, respectively, with the most abundant components being elaidic (37.26%). The oil did not demonstrate any antimicrobial or antifungal activity when tested alone, presenting MIC values ≥ 1024 µg/mL. However, when associated with antibiotics, it demonstrated synergistic effects with gentamicin against all the bacterial lineages assayed, and antagonistic effects with amikacin and neomycin against strains of Escherichia coli. Conclusions: Oil extracted from the body fat of S. pullatus did not demonstrate any inhibitory effects on bacterial or fungal activities, but was effective in modulating the effects of certain antibiotics. [ABSTRACT FROM AUTHOR]

In the present work, we investigate how stmcmral defects in graphene can change its transport properties. In particular, we show that breaking of the sublattice symmetry in a graphene monolayer overcomes the Klein effect, leading to confined states of massless Dirac fermions. Experimentally, this corresponds to chemical bonding of foreign atoms to carbon atoms, which attach themselves to preferential positions on one of the two sublattices. In addition, we consider the scattering off a tensor barrier, which describes the rotation of the honeycomb cells of a given region around an axis perpendicular to the graphene layer. We demonstrate that in this case the intervalley mixing between the Dirac points emerges, and that Klein tunneling occurs. [ABSTRACT FROM AUTHOR]

Effective quantum field theoretical continuum models for graphene are investigated. The models include a complex scalar field and a vector gauge field. Different gauge theories are considered and their gap patterns for the scalar, vector, and fermion excitations are investigated. Different gauge groups lead to different relations between the gaps, which can be used to experimentally distinguish the gauge theories. In this class of models the fermionic gap is a dynamic quantity. The finite-energy vortex solutions of the gauge models have the flux of the "magnetic field" quantized, making the Bohm-Aharonov effect active even when external electromagnetic fields are absent. The flux comes proportional to the scalar field angular momentum quantum number. The zero modes of the Dirac equation show that the gauge models considered here are compatible with fractionalization. [ABSTRACT FROM AUTHOR]

Abstract: The connection between QCD, a nonlocal Nambu–Jona-Lasinio type model and the Landau gauge gluon propagator is explored. This two point function is parameterized by a functional form which is compatible with Dyson–Schwinger and lattice QCD results. Demanding the nonlocal model to reproduce the experimental values for the pion mass, the pion decay constant, and the light quark condensate we conclude that low energy physics does not distinguish between the so-called decoupling and scaling solutions of the Dyson–Schwinger equations. This result means that, provided that the model parameters are chosen appropriately, one is free to choose any of the above scenarios. Furthermore, the nonlocal Nambu–Jona-Lasinio quark model considered here is chiral invariant and satisfies the GMOR relation at the 1% level of precision. [ABSTRACT FROM AUTHOR]

Abstract: The metrological compatibility of n(234U)/n(238U), n(235U)/n(238U) and n(236U)/n(238U) isotope amount ratio measurement results obtained by gas source mass spectrometry (GSMS), thermal ionisation mass spectrometry (TIMS) and multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) techniques in a set of low-enriched uranium samples is demonstrated in this study. The impact of the correlation between certified isotope reference materials on the metrological compatibility of measured isotope amount ratios is also discussed. The metrological concepts defined in the VIM 3rd edition and the measurement uncertainty evaluation according to the BIPM-GUM guide was thoroughly applied in this work. [Copyright &y& Elsevier]

The compatibility of the pure power law infrared solution of QCD and lattice data for the gluon and ghost propagators in Landau gauge is discussed. For the gluon propagator, the lattice data are well described by a pure power law with an infrared exponent κ∼0.53, in the Dyson–Schwinger notation. κ is measured using a technique that suppresses finite volume effects. This value is consistent with a vanishing zero momentum gluon propagator, in agreement with the Gribov–Zwanziger confinement scenario. For the ghost propagator, the lattice data seem not to follow a pure power law, at least for the range of momenta accessed in our simulation. [ABSTRACT FROM AUTHOR]

A generalized Cho-Faddeev-Niemi ansatz for SU(3) Yang-Mills is investigated. The corresponding classical field equations are solved for its simplest parametrization. From these solutions it is possible to define a confining non-relativistic central potential used to study heavy quarkonia. The associated spectra reproduces the experimental spectra with an error of less than 3% for charmonium and 1% for bottomonium. Moreover, the recently discovered new charmonium states can be accommodate in the spectra, keeping the same level of precision. The leptonic widths show good agreement with the recent measurements. The charmonium and bottomonium E1 electromagnetic transitions widths are computed and compared with the experimental values. [ABSTRACT FROM AUTHOR]

Abstract: The measurement of n(235U)/n(238U) isotope amount ratio in a set of representative uranium samples with enrichment levels ranging from 0.5 to 20.0wt.% of 235U was carried out by thermal ionization mass spectrometry using the traditional and the total evaporation methods. The uncertainties of the measurement results were evaluated according to the recommendations of the ISO guide to the expression of uncertainty in measurement. They were then compared to the requirements of the IAEA international target values for measurement uncertainties in safeguarding nuclear materials. [Copyright &y& Elsevier]

We revisit the problem of non-uniqueness of harmonic magnetic field models in a region outside a sphere containing the field sources, when only intensity values on the sphere surface are known. Using the angular momentum algebra and the Clebsch-Gordan coefficients, we are able to treat different aspects of this non-uniqueness following a unified line of reasoning. In this new framework, we first recover two Backus results, namely the proof of uniqueness in the case of a field generated by a finite number of harmonics and the recurrence relation that defines the well-known Backus series. This formalism allows us to extend previous studies in two ways: firstly, we show how to produce an harmonic series orthogonal on the sphere to some other arbitrary harmonic series; secondly, we outline a new method for computing magnetic field models starting from scalar intensity values alone. [ABSTRACT FROM AUTHOR]

We address the problem of Gribov copies in lattice QCD. The gluon propagator is computed, in the Landau gauge, using 302 (β=5.8) 124 SU(3) configurations gauge fixed to different copies. The results of the simulation shows that: (i) the effect of Gribov copies is small (less than 10%); (ii) Gribov copies change essentially the lowest momenta components (q<2.6 GeV); (iii) within the statistical accuracy of our simulation, the effect of Gribov copies is resolved if statistical errors are multiplied by a factor of two or three. Moreover, when modelling the gluon propagator, different sets of Gribov copies produce different sets of parameters not, necessarily, compatible within one standard deviation. Finally, our data supports a gluon propagator which, for large momenta, behaves like a massive gluon propagator with a mass of 1.1 GeV. [Copyright &y& Elsevier]

Measurements of the grid-to-plate current-voltage characteristics of the corona triode are reported. A space-charge-limited current (SCLC) characteristic is observed to hold for low values of the plate current IP, provided that the grid voltage Vg is corrected for a counter potential Vr. The analysis of experimental results indicates that Vr is due both to penetration of field lines through the grid and to the corona wind. However, departure from SCLC regime is observed at higher plate currents, when the ion supply from the corona current becomes insufficient to afford it. A simplified theory is developed in order to explain the results. In the calculation, a layer of recombination centers is substituted for the grid. The model fits the whole characteristics and leads to reasonable value of the parameters defined by the model. [ABSTRACT FROM AUTHOR]

Context: For an ensiling to succeed, the knowledge about the factors that might influence the fermentation dynamics and nutrient loss is mandatory. One of the strategies is the use of additives such as tannins, as they can decrease proteolysis and increase the total organic acids. Aims: The aim was to investigate the effects of tannins on fermentation patterns and nutritional value of sorghum silage. Methods: Silages containing 0.0, 7.5, 15.0, 22.5, and 30.0 g/kg of tannin on fresh matter were studied. To produce the silage, the tannin was added to the forage and manually homogenised before ensiling. The study was conducted in three experiments. In the first experiment, five replications of each level of inclusion were produced and assigned in a completely randomised design. The chemical composition and fermentation patterns of all experimental units were evaluated. The second experiment consisted of analysing the aerobic deterioration by using a PET bottles system. This experiment was conducted in a completely randomised split plot, with five replications and five treatments with the inclusion of different levels of tannin (main plots) and the hours of exposure of silage to air (subplot). In the third experiment, five levels of tannin (main plots) and incubation times (subplots) were evaluated as for in situ digestibility (ruminal degradability) in a randomised blocks design with three replications (animals). Key results: The inclusion of tannins in sorghum silage caused quadratic effects on pH, acetic acid, lactic acid, total organic acids, ammonia nitrogen, dry matter content, crude protein content and in situ digestibility, when the level varied from 10.5 to 22.7 g tannin/kg fresh matter. There was a decreasing linear effect for aerobic deterioration as increasing levels of tannin in sorghum silage. Conclusions: The inclusion of tannin as an additive in sorghum silage is recommended for the production of good quality silage. The use of condensed tannins optimise fermentation patterns (especially increasing lactic acid and decreasing ammoniacal nitrogen), chemical composition, providing less aerobic deterioration and improve digestibility. Implications: This study revealed that condensed tannins can improve fermentation patterns and the nutritive value of sorghum silage. Tannins are secondary compounds that act to protect proteins from microbial degradation. Affinity between tannins and proteins is due to the presence of multiple phenolic hydroxyl groups in tannins, which promotes an easier connection with proteins. Tannins can decrease proteolysis in silage, inhibiting microbial action, through the protein-bound linkage in the ensiled mass. Thus, it is recommended to include of tannin as an additive in sorghum silage to improve fermentation patterns, diminish aerobic deterioration, as well as improve digestibility. [ABSTRACT FROM AUTHOR]

We report on the infrared limit of the quenched lattice Landau gauge gluon and ghost propagators as well as the strong-coupling constant computed from large asymmetric lattices. The infrared lattice propagators are compared with the pure power law solutions from Dyson-Schwinger equations (DSE). For the gluon propagator, the lattice data is compatible with the DSE solution. The preferred measured gluon exponent being ∼0.52, favouring a vanishing propagator at zero momentum. The lattice ghost propagator shows finite-volume effects and, for the volumes considered, the propagator does not follow a pure power law. Furthermore, the strong-coupling constant is computed and its infrared behaviour investigated. [ABSTRACT FROM AUTHOR]

An approximate dual representation for non-Abelian lattice gauge theories in terms of a new set of dynamical variables, the plaquette occupation numbers (PONs) that are natural numbers, is discussed. They are the expansion indices of the local series of the expansion of the Boltzmann factors for every plaquette of the Yang-Mills action. After studying the constraints due to gauge symmetry, the SU(2) gauge theory is solved using Monte Carlo simulations. For a PONs configuration the weight factor is given by Haar-measure integrals over all links whose integrands are products of powers of plaquettes. Herein, updates are limited to changes of the PON at a plaquette or all PONs on a coordinate plane. The Markov chain transition probabilities are computed employing truncated maximal trees and the Metropolis algorithm. The algorithm performance is investigated with different types of updates for the plaquette mean value over a large range of βs. Using a 124 lattice very good agreement with a conventional heath bath algorithm is found for the strong and weak coupling limits. Deviations from the latter being below 0.1% for 2.5<β<3. The mass of the lightest JPC=0++ glueball is evaluated and reproduces the results found in the literature. [ABSTRACT FROM AUTHOR]

The Batalin-Vilkovisky function is a central component in the modern formulation of the background field method and the physical applications derived from it. In the present work we report on novel lattice results for this particular quantity, obtained by capitalizing on its equality with the Kugo-Ojima function in the Landau gauge. The results of the lattice simulation are in very good agreement with the predictions derived from a continuum analysis based on the corresponding Schwinger-Dyson equations. In addition, we show that an important relation connecting this function with the ghost propagator is fulfilled rather accurately. With the aid of these results, we carry out the first completely lattice-based determination of the process-independent strong running interaction, employed in a variety of phenomenological studies. [ABSTRACT FROM AUTHOR]

The computation of the optical conductivity of strained and deformed graphene is discussed within the framework of quantum field theory in curved spaces. The analytical solutions of the Dirac equation in an arbitrary static background geometry for one dimensional periodic deformations are computed, together with the corresponding Dirac propagator. Analytical expressions are given for the optical conductivity of strained and deformed graphene associated with both intra and interbrand transitions. The special case of small deformations is discussed and the result compared to the prediction of the tight-binding model. [ABSTRACT FROM AUTHOR]

The infrared behavior of gluon and ghost propagators in Yang–Mills gauge theories is of central importance for the understanding of confinement in QCD. While analytic studies using Schwinger–Dyson equations predict the same infrared exponents for the SU(2) and SU(3) gauge groups, lattice simulations usually assume that the two cases are different, although their qualitative infrared features may be the same. We carry out a comparative study of lattice (Landau) propagators for both gauge groups. Our data were especially produced with equivalent lattice parameters to allow a careful comparison of the two cases. [ABSTRACT FROM AUTHOR]

Many amphibian species are vulnerable to environmental changes, especially in the tropics where presumably a large number of species have evolved narrow niches. Rapid environmental changes, such as deforestation, may promote stress responses in anurans that could affect population viability. The stress response in vertebrates is highly conserved, often involving the liberation of glucocorticoids hormones and the recruitment of immune competent cells. The objective of this work was to evaluate leukocyte profiles among individuals of two neotropical anuran species affected by anthropogenic habitat alteration. We took blood samples from adult individuals of Physalaemus cuvieri and Scinax x‐signatus in natural and converted habitats in NE Brazil. We analyzed differential leukocyte counts, where increases in neutrophils and decreases in lymphocytes are indicative of a stress response. Specimens of S. x‐signatus captured in highly altered habitats presented a higher neutrophil:lymphocyte (N:L) ratios than individuals from natural habitats. In contrast, P. cuvieri individuals exhibited no difference in N:L ratios between habitat types. These results suggest that the immune response depends on the species and the level of habitat alteration. Although S. x‐signatus can be considered a generalist species, individuals from this species exhibited increased stress response associated with habitat alteration. The lack of a strong stress response of P. cuvieri, may suggest that this species is more tolerant of habitat alteration or that those individuals have acclimated to anthropogenic stressors more rapidly than S. x‐signatus. These variable responses of immune function in highly altered habitats suggest avenues for future experimental work that examines responses to multiple stressors, including disease, which could scale to population trends in altered habitats. [ABSTRACT FROM AUTHOR]

Oscillons are time-dependent, localized in space, extremely long-lived states in nonlinear scalar-field models, while kinks are topological solitons in one spatial dimension. In the present work, we show new classes of oscillons and oscillating kinks in a system of two nonlinearly coupled scalar fields in 1 + 1 spatiotemporal dimensions. The solutions contain a control parameter, the variation of which produces oscillons and kinks with a flat-top shape. The model finds applications in condensed matter, cosmology, and high-energy physics. [ABSTRACT FROM AUTHOR]

The effects induced by antibiotics on the bacterial membrane may be correlated with their bactericidal activity and such molecular-level interactions can be probed with Langmuir monolayers representing the cell membrane. In this study, we investigated the interaction between [Ru(mcbtz)2(PPh3)2] (RuBTZ, mcbtz = 2-mercaptobenzothiazoline) and [Ru(mctz)2(PPh3)2] (RuCTZ, mctz = 2-mercaptothiazoline) with Langmuir monolayers of a lipid extract of Escherichia coli, an extract of lipopolysaccharides (LPSs) and a zwitterionic phospholipid, dioleoylphosphatidyl choline (DOPC). RuBTZ and RuCTZ had little effects on DOPC, which is consistent with their negligible toxicity toward mammalian cells that may be approximated by a zwitterionic monolayer. Also little were their effects on LPSs. In contrast, RuBTZ and RuCTZ induced expansion in the surface pressure isotherms and decreased the compressional modulus of the E. coli lipid extract. While the more hydrophobic RuBTZ seemed to affect the hydrophobic tails of the E. coli extract monolayer to a larger extent, according to polarization modulation infrared reflection absorption spectroscopy results, evidence of a stronger RuBTZ interaction could not be confirmed unequivocally. Therefore, the interaction with the E. coli cell membrane cannot be directly correlated with the observed higher bactericidal activity of RuBTZ, in comparison to that of RuCTZ. This appears to be a case in which Langmuir monolayer studies do not suffice to determine the mechanisms responsible for the bactericidal activity. [ABSTRACT FROM AUTHOR]

Yttrium-doped barium zirconate (BZY), one of the protonic conductors considered to be used as solid electrolyte in solid oxide fuel cells (SOFC) operating at temperatures lower than the one found in conventional oxide-ion SOFCs, still presents some challenges to reach high density and high electrical conductivity: the difficulty to sinter at temperatures well below its melting point and the blocking of the conducting species at the grain boundaries. We describe an experimental sequence to prepare powders and to obtain highly dense BZY ceramic pellets with enhanced electrical conductivity, using either phosphor pentoxide (PO), boron oxide (BO) or zinc oxide (ZnO) as sintering aid. The reactions leading to sintering ceramic pellets with densities higher than 94% of the theoretical density and improved electrical performance are monitored by thermal analyses. BZY with the addition of 5 mass% PO or 2 mass% ZnO shows a tenfold enhancement of the electrical conductivity. [ABSTRACT FROM AUTHOR]

Herein we present a novel sensor for the detection of monosaccharides (e.g. glucose, fructose) in solution, using electrical impedance spectroscopy. The sensor is based on carbon interdigitated electrodes, printed on paper using screen printing. The surface of the electrodes was modified with a thin layer of hydrogel containing acrylamide copolymerised with 20 mol% 3-(Acrylamido)phenylboronic acid (PBA). It was observed that the hydrogel layers containing 20 mol% PBA swell considerably in the presence of glucose and fructose. This in turn changes the measured impedance across the electrodes, making it a suitable sensor for the quantitative detection of saccharides. We investigated the impedance and capacitance variations with different concentrations of glucose and fructose (0–5 mM) in aqueous phosphate buffer solutions. Variations in impedance were attributed to changes in the dielectric properties of the hydrogel under an applied electric field, due to swelling of the hydrogel layer induced by uptake and binding of sugar molecules to the boronate species within the gel. Impedance measurements at 1 kHz demonstrated that hydrogel swelling leads to an increased mobility of ions within the swollen hydrogel layer. The impedance decreased with increasing sugar concentration and the relative capacitance curves are markedly different for fructose and glucose, as the hydrogel exhibits greater swelling in the presence of fructose than glucose over the same concentration range. As the proposed sensor was shown to be suitable for the detection of glucose at concentration levels found in human sweat, future work will focus on the incorporation of these modified paper-based electrodes into wearable skin patches for non-invasive sugar monitoring in sweat. [ABSTRACT FROM AUTHOR]

Our research involves the development of a pH-sensitive chitosan-tetraethyl orthosilicate interpenetrating polymer network (Chi-TEOS IPN) suitable for the introduction of ordered silica nanoparticles. The pH-sensitive properties of the IPN provide an innovative framework for ordered colloidal silica (SiO) films known as photonic crystals. The pH-sensitive properties of chitosan occur naturally due to its cationic polyelectrolyte structure; cross-linking with TEOS provides mechanical strength and incorporation of the silica photonic crystal provides a means of optical detection for a pH-driven expansion mechanism. Chitosan-tetraethyl orthosilicate-silica (Chi-TEOS-SiO) composites are formed through a three-step mechanism in which the silica photonic crystal and Chi-TEOS IPN hydrogel are synthesized separately and then combined to form the Chi-TEOS-SiO composite. The silica photonic crystals, IPN membranes and final composite structures were analysed separately through optical, mechanical and swelling studies. Through the successful fabrication of a Chi-TEOS-SiO composite we propose a membrane suitable for applications in environmental, chemical and biological sensing of pH. [ABSTRACT FROM AUTHOR]

Objective: The aim of this clinical randomized double-blind split-mouth study was to assess the effectiveness of a 6% hydrogen peroxide with nitrogen-doped titanium dioxide light activated bleaching agent.Method: 31 patients were treated with: one upper hemiarcade with a 35% hydrogen peroxide bleaching agent and the other hemiarcade with a 6% hydrogen peroxide. Two applications were completed each treatment session and three sessions were appointed, with one week interval between them. Tooth colour was registered each session and 1 week and 1 months after completing the treatment by spectrophotometer, registering parameters L*, a* and b*, and subjectively using VITA Classic guide. Tooth sensitivity was registered by VAS and patient satisfaction and self-perception result was determined using OHIP-14. Tooth colour variation and sensitivity were compared between both bleaching agents.Results: Both treatment showed a change between baseline colour and all check-points with a ΔE=5.57 for 6% and of ΔE=7.98 for the 35% one month after completing the (p<0.05). No statistical differences were seen when subjective evaluations were compared. Also, no differences were seen in tooth sensitivity between bleaching agents. OHIP-14 questionnaire demonstrated a significant change for all patients after bleaching.Conclusions: A 6% hydrogen peroxide with nitrogen-doped titanium dioxide light activated agent is effective for tooth bleaching, reaching a ΔE of 5.57 one month after completing the treatment, with no clinical differences to a 35% agent neither in colour change or in tooth sensitivity.Clinical Significance: A low concentration hydrogen peroxide bleaching agent may reach good clinical results with less adverse effects. [ABSTRACT FROM AUTHOR]

Oneof the major challenges in drug design is to identify compoundswith potential toxicity toward target cells, preferably with molecular-levelunderstanding of their mode of action. In this study, the antitumorproperty of a ruthenium complex, mer-[RuCl3(dppb)(VPy)] (dppb =1,4-bis(diphenylphosphine)butane and VPy = 4-vinylpyridine)(RuVPy), was analyzed. Results showed that this compound led to amortality rate of 50% of HEp-2 cell with 120 ± 10 μmolL–1, indicating its high toxicity. Then, to proveif its mode of action is associated with its interaction with cellmembranes, Langmuir monolayers were used as a membrane model. RuVPyhad a strong effect on the surface pressure isotherms, especiallyon the elastic properties of both the zwitterionic dipalmitoylphosphatidylcholine(DPPC) and the negatively charged dipalmitoylphosphatidylglycerol(DPPG) phospholipids. These data were confirmed by polarization-modulatedinfrared reflection–absorption spectroscopy (PM-IRRAS). Inaddition, interactions between the positive group from RuVPy and thephosphate group from the phospholipids were corroborated by densityfunctional theory (DFT) calculations, allowing the determination ofthe Ru complex orientation at the air–water interface. Althoughpossible contributions from receptors or other cell components cannotbe discarded, the results reported here represent evidence for significanteffects on the cell membranes which are probably associated with thehigh toxicity of RuVPy. [ABSTRACT FROM AUTHOR]

Plant roots are among most intensively studied biological systems in gravity research. Altered gravity induces asymmetric cell growth leading to root bending. Differential distribution of the phytohormone auxin underlies root responses to gravity, being coordinated by auxin efflux transporters from the PIN family. The objective of this study was to compare early transcriptomic changes in roots of Arabidopsis thaliana wild type, and pin2 and pin3 mutants under parabolic flight conditions and to correlate these changes to auxin distribution. Parabolic flights allow comparison of transient 1− g, hypergravity and microgravity effects in living organisms in parallel. We found common and mutation-related genes differentially expressed in response to transient microgravity phases. Gene ontology analysis of common genes revealed lipid metabolism, response to stress factors and light categories as primarily involved in response to transient microgravity phases, suggesting that fundamental reorganisation of metabolic pathways functions upstream of a further signal mediating hormonal network. Gene expression changes in roots lacking the columella-located PIN3 were stronger than in those deprived of the epidermis and cortex cell-specific PIN2. Moreover, repetitive exposure to microgravity/hypergravity and gravity/hypergravity flight phases induced an up-regulation of auxin responsive genes in wild type and pin2 roots, but not in pin3 roots, suggesting a critical function of PIN3 in mediating auxin fluxes in response to transient microgravity phases. Our study provides important insights towards understanding signal transduction processes in transient microgravity conditions by combining for the first time the parabolic flight platform with the transcriptome analysis of different genetic mutants in the model plant, Arabidopsis. [ABSTRACT FROM AUTHOR]

The honeycomb carbon structure of graphene and nanotubes has a dynamics which can give rise to a spectrum. This can be excited via the interaction with an external electromagnetic field. In this work, nonlinear waves on graphene and nanotubes associated with the carbon structure are investigated using a gauge model. Typical energies are estimated and their scaling with the nanoribbon width investigated. Furthermore, the soliton-photon interaction depends on the incident photon polarization. In particular, we find that the nanoribbon is transparent when the polarization is along the largest length. Relying on the scaling with the width, we suggest a way to experimentally identify the soliton waves in nanoribbons. [ABSTRACT FROM AUTHOR]

Electrostatic and hydrophobic interactions govern mostof the propertiesof supramolecular systems, which is the reason determining the degreeof ionization of macromolecules has become crucial for many applications.In this paper, we show that high-resolution ultraviolet spectroscopy(VUV) can be used to determine the degree of ionization and its effecton the electronic excitation energies of layer-by-layer (LbL) filmsof poly(allylamine hydrochloride) (PAH) and poly[1-[4-(3-carboxy-4hydroxyphenylazo)benzene sulfonamido]-1,2-ethanediyl, sodium salt](PAZO). A full assignment of the VUV peaks of these polyelectrolytesin solution and in cast or LbL films could be made, with their pHdependence allowing us to determine the pKausing the Henderson-Hasselbach equation. The pKafor PAZO increased from ca. 6 in solution to ca. 7.3in LbL films owing to the charge transfer from PAH. Significantly,even using solutions at a fixed pH for PAH, the amount adsorbed onthe LbL films still varied with the pH of the PAZO solutions due tothese molecular-level interactions. Therefore, the procedure basedon a comparison of VUV spectra from solutions and films obtained underdistinct conditions is useful to determine the degree of dissociationof macromolecules, in addition to permitting interrogation of interfaceeffects in multilayer films. [ABSTRACT FROM AUTHOR]

The development of polymer-based photovoltaic devices brings the promise of low-cost and lightweight solar energy conversion systems. This technology requires new materials and device architectures with enhanced efficiency and lifetime, which depends on the understanding of charge-transport mechanisms. Organic films combined with electronegative nanoparticles may form systems with efficient dissociation of the photogenerated excitons, thus increasing the number of carriers to be collected by the electrodes. In this paper we investigate the steady-state photoconductive action spectra of devices formed by a bilayer of regio-regular poly(3-hexylthiophene) (RRP3HT) and TiO sandwiched between ITO and aluminum electrodes (ITO/TiO:RRP3HT/Al). Photocurrents were measured for distinct bias voltages with illumination from either side of the device. Heterojunction structures were prepared by spin coating a RRP3HT film on an already deposited TiO layer on ITO. Symbatic and antibatic curves were obtained and a model for photocurrent action spectra was able to fit the symbatic responses. The quantum yield increased with the electric field, indicating that exciton dissociation is a field-assisted process as in an Onsager mechanism. Furthermore, the quantum yield was significantly higher when illumination was carried out through the ITO electrode onto which the TiO layer was deposited, as the highly electronegative TiO nanoparticles were efficient in exciton dissociation. [ABSTRACT FROM AUTHOR]

We show that the assumption of a nontrivial zero band gap for a graphene sheet within an effective relativistic field theoretical model description of interacting Dirac electrons on the surface of graphene describes the experimental band gap of graphene nanoribbons for a wide range of widths. The graphene band gap is dynamically generated, corresponding to a nontrivial gapless solution, found in the limit of an infinitely wide graphene ribbon. The nanoribbon band gap is determined by the experimental graphene work function. [ABSTRACT FROM AUTHOR]

Abstract: The upgraded HADES inner TOF Wall will cover a total area of 8m2 with 1116 variable-geometry 4-gap, symmetric, timing RPCs, readout by 2232 time and charge channels. Each RPC is individually shielded for robust multi-hit performance and optimum use of the readout channels (crosstalk minimization). The double layer configuration provides a useful degree of redundancy for very accurate timing of a large fraction of all particles crossing the detector. In this paper we describe the concept of the detector, its inner structure and the multi-hit performance. [Copyright &y& Elsevier]