Non-Fermi-liquid behavior in UCu(4+x)Al(8-x) compounds

We report on experimental studies of the Kondo physics and the development of non-Fermi-liquid scaling in UCu(4+x)Al(8-x) family. We studied 7 different compounds with compositions between x = 0 and 2. We measured electrical transport (down to 65 mK) and thermoelectric power (down to 1.8 K) as a function of temperature, hydrostatic pressure, and/or magnetic field. Compounds with Cu content below x = 1.25 exhibit long-range antiferromagnetic order at low temperatures. Magnetic order is suppressed with increasing Cu content and our data indicate a possible quantum critical point at x(cr) approximate to 1.15. For compounds with higher Cu content, non-Fermi-liquid behavior is observed. Non-Fermi-liquid scaling is inferred from electrical resistivity results for the x = 1.25 and 1.5 compounds. For compounds with even higher Cu content, a sharp kink occurs in the resistivity data at low temperatures, and this may be indicative of another quantum critical point that occurs at higher Cu compositions. For the magnetically ordered compounds, hydrostatic pressure is found to increase the Neel temperature, which can be understood in terms of the Kondo physics. For the non-magnetic compounds, application of a magnetic field promotes a tendency toward Fermi-liquid behavior. Thermoelectric power was analyzed using a two-band Lorentzian model, and the results indicate one fairly narrow band (10 meV and below) and a second broad band (around hundred meV). The results imply that there are two relevant energy scales that need to be considered for the physics in this family of compounds. (C) 2011 Elsevier B.V. All rights reserved.

Electron dephasing scattering rate in two-dimensional GaAs/InGaAs heterostructures with embedded InAs quantum dots

We report a comprehensive study of weak-localization and electron-electron interaction effects in a GaAs/InGaAs two-dimensional electron system with nearby InAs quantum dots, using measurements of the electrical conductivity with and without magnetic field. Although both the effects introduce temperature dependent corrections to the zero magnetic field conductivity at low temperatures, the magnetic field dependence of conductivity is dominated by the weak-localization correction. We observed that the electron dephasing scattering rate tau(-1)(phi), obtained from the magnetoconductivity data, is enhanced by introducing quantum dots in the structure, as expected, and obeys a linear dependence on the temperature and elastic mean free path, which is against the Fermi-liquid model. (c) 2008 American Institute of Physics. [DOI: 10.1063/1.2996034]

A comparison of the leaf-litter ant fauna in a secondary atlantic forest with an adjacent pine plantation in southeastern Brazil

We investigated the influence of Pinus afforestation on the structure of leaf-litter ant communities in the southeastern Brazilian Atlantic Forest, studying an old secondary forest and a nearly 30 year-old never managed Pinus elliottii reforested area. A total of 12,826 individual ants distributed among 95 species and 32 genera were obtained from 50 1 m² samples/ habitat. Of these, 60 species were recorded in the pine plantation and 82 in the area of Atlantic forest; almost 50% of the species found in the secondary forest area were also present in the pine plantation. The number of species per sample was significantly higher in the secondary forest than in the pine plantation. Forest-adapted taxa are the most responsible for ant species richness differences between areas, and the pine plantation is richer in species classified as soil or litter omnivorous-dominants. The specialized ant predators registered in the pine plantation, as seven Dacetini, two Basiceros, two Attini and two Discothyrea, belong to widely distributed species. The NMDS (non-metric multidimensional scaling) ordination also suggested strong differences in similarity among samples of the two areas. Furthermore, this analysis indicated higher sample heterogeneity in the secondary forest, with two clusters of species, while in the pine plantation the species belong to a single cluster. We applied the ant mosaic hypothesis to explain the distribution of the leaf-litter fauna and spatial autocorrelation tests among samples. We argue that the results are likely related to differences in quality and distribution of the leaf-litter between the pine plantation and the secondary area.

Ant community richness and composition across a gradient from Eucalyptus plantations to secondary Atlantic Forest

Secondary forests and exotic tree plantations are expanding across tropical landscapes. However, our current understanding of the value of these human-dominated forest landscapes for invertebrate biodiversity conservation is still very poor. In this paper, we use the leaf-litter ant fauna to assess invertebrate diversity in one commercially managed Eucalyptus plantation (four years old), two abandoned plantations of different regeneration ages (16 and 31 years), and one neighboring secondary Atlantic Forest in Southeastern Brazil. There was a clear gradient in species richness from the secondary forest to the managed Eucalyptus plantation; richness and diversity peaked in secondary forest and in the older regenerating Eucalyptus plantation. Significantly more species were recorded in secondary forest samples than in Eucalyptus plantations, but Eucalyptus plantations had a similar level of richness. Furthermore, a non-metric multidimensional scaling analysis revealed clear differences in species composition between the younger managed Eucalyptus plantation (understory absent) and habitats with sub-developed or developed understory. Eucalyptus plantations were characterized by an assemblage of widespread, generalist species very different from those known to occur in core forest habitats of southeastern Brazil. Our results indicate that while older regenerating Eucalyptus plantations can provide habitat to facilitate the persistence of generalist ant species, it is unlikely to conserve most of the primary forest species, such as specialized predators, Dacetini predators, and nomadic species.

Forced convection to laminar flow of liquid egg yolk in circular and annular ducts

The steady-state heat transfer in laminar flow of liquid egg yolk - an important pseudoplastic fluid food - in circular and concentric annular ducts was experimentally investigated. The average convection heat transfer coefficients, determined by measuring temperatures before and after heating sections with constant temperatures at the tube wall, were used to obtain simple new empirical expressions to estimate the Nusselt numbers for fully established flows at the thermal entrance of the considered geometries. The comparisons with existing correlations for Newtonian and non-Newtonian fluids resulted in excellent agreement. The main contribution of this work is to supply practical and easily applicable correlations, which are, especially for the case of annulus, rather scarce and extensively required in the design of heat transfer operations dealing with similar shear-thinning products. In addition, the experimental results may support existing theoretical analyses.

Supramolecular polymorphism of DNA in non-cationic L(alpha) lipid phases

The structure of a complex between hydrated DNA and a non-cationic lipid is studied, including its phase diagram. The complex is spontaneously formed by adding DNA fragments (ca. 150 base pairs in length) to non-cationic lipids and water. The self-assembly process often leads to highly ordered structures. The structures were studied by combining X-ray scattering, fluorescence and polarized microscopy, as well as freeze-fracture experiments with transmission electron microscopy. We observe a significant increase of the smectic order as DNA is incorporated into the water layers of the lamellar host phase, and stabilization of single phase domains for large amounts of DNA. The effect of confinement on DNA ordering is investigated by varying the water content, following three dilution lines. A rich polymorphism is found, ranging from weakly correlated DNA-DNA in-plane organizations to highly ordered structures, where transmembrane correlations lead to the formation of columnar rectangular and columnar hexagonal superlattices of nucleotides embedded between lipid lamellae. From these observations, we suggest that addition of DNA to the lamellar phase significantly restricts membrane fluctuations above a certain concentration and helps the formation of the lipoplex. The alteration of membrane steric interactions, together with the appearance of interfacial interactions between membranes and DNA molecules may be a relevant mechanism for the emergence of highly ordered structures in the concentrated regime.

Determination of Cr, Fe, Co, Ni, Cu, Zn, As and Pb in liquid chemical waste by energy dispersive X-ray fluorescence

A method for simultaneous determination of Cr, Fe, Co, Ni, Cu, Zn, As e Pb in liquid chemical waste using Energy Dispersive X-Ray Fluorescence (EDXRF) technique was evaluated. A small sample amount (200 mu L) was dried on a 6.35 mu m thickness Mylar film at 60 degrees C and the analyses were carried out using an EDXRF spectrometer operated with an X-ray Mo tube (Zr filter) at 30 kV/20 mA. The acquisition time was 300 s and the Ga element was utilized as internal standard at 25 mg/L for quantitative analysis. The method trueness was assessed by spiking and the detection limit for those elements ranged from 0.39 to 1.7 mg/L. This method is notable because it assists the choice of the more appropriated waste treatment procedure, in which inter elemental interference is a matter of importance. In addition, this inexpensive method allows a non-destructive determination of the elements from (19)K to (92)U simultaneously.

Precursor system of liquid crystalline phase containing propolis microparticles for the treatment of periodontal disease: Development and characterization

Precursor systems of liquid crystalline phase were prepared using the surfactant PPG-5-Ceteth-20, isopropyl myristate, and water; gelatin microparticles containing propolis were then added into these systems. Homogeneity of dispersion, the in-system microparticle morphology, and sedimentation behavior of each formulation were evaluated. The rheological and mechanical properties (hardness, compressibility, and adhesiveness), the work of syringing, and the propolis release profile were also evaluated. All the formulations exhibited pseudoplastic flow and thixotropy, and they displayed storage modulus, loss modulus, dynamic viscosity, and loss tangent that depended on temperature, frequency, and composition. Mechanical properties varied significantly among the formulations being affected by changes in the composition and temperature. Raising the concentration of surfactant and adding propolis microparticles significantly decreased the work of syringing. The drug release was non-Fickian (anomalous) and there was no significant difference between the tested systems in the times required for 10%, 30%, and 50% release of the initial drug loading.

Purification and Partial Characterization of an Exo-polygalacturonase from Paecilomyces variotii Liquid Cultures

An extracellular polygalacturonase (PG) produced from Paecilomyces variotii was purified to homogeneity through two chromatography steps using DEAE-Fractogel and Sephadex G-100. The molecular weight of P. variotii PG was 77,300 Da by gel filtration and SDS-PAGE. PG had isoelectric point of 4.37 and optimum pH 4.0. PG was very stable from pH 3.0 to 6.0. The extent of hydrolysis of different pectins by the purified enzyme was decreased with an increase in the degree of esterification. PG had no activity toward non-pectic polysaccharides. The apparent K (m) and V (max) values for hydrolyzing sodium polypectate were 1.84 mg/mL and 432 A mu mol/min/mg, respectively. PG was found to have temperature optimum at 65 A degrees C and was totally stable at 45 A degrees C for 90 min. Half-life at 55 A degrees C was 50.6 min. Almost all the examined metal cations showed partial inhibitory effects under enzymatic activity, except for Na(+1), K(+1), and Co(+2) (1 mM) and Cu(+2) (1 and 10 mM).

NKX2.5 mutations in patients with non-syndromic congenital heart disease

Background: Cardiac development is a complex and multifactorial biological process. Heterozygous mutations in the transcription factor NKX2.5 are between the first evidence of a genetic cause for congenital heart defects in human beings. In this study, we evaluated the presence and frequency of mutations in the NKX2.5 gene on 159 unrelated patients with a diverse range of non-syndromic congenital heart defects (conotruncal anomalies, septal defects, left-sided lesions, right-sided lesions, patent ductus arteriosus and Ebstein`s anomaly). Methods: The coding region of the NKX2.5 locus was amplified by polymerase chain reaction and mutational analysis was performed using denaturing high performance liquid chromatography (DHPLC) and DNA sequencing. Results: We identified two distinct mutations in the NKX2.5 coding region among the 159 (1.26%) individuals evaluated. An Arg25Cys mutation was identified in a patient with Tetralogy of Fallot. The second mutation found was an Ala42Pro in a patient with Ebstein`s anomaly. Conclusions: The association of NKX2.5 mutations is present in a small percentage of patients with non-syndromic congenital heart defects and may explain only a few cases of the disease. Screening strategies considering the identification of germ-line molecular defects in congenital heart disease are still unwarranted and should consider other genes besides NKX2.5. (C) 2008 Elsevier Ireland Ltd. All rights reserved.

Microscopic origin of non-Gaussian distributions of financial returns

In this paper we study the possible microscopic origin of heavy-tailed probability density distributions for the price variation of financial instruments. We extend the standard log-normal process to include another random component in the so-called stochastic volatility models. We study these models under an assumption, akin to the Born-Oppenheimer approximation, in which the volatility has already relaxed to its equilibrium distribution and acts as a background to the evolution of the price process. In this approximation, we show that all models of stochastic volatility should exhibit a scaling relation in the time lag of zero-drift modified log-returns. We verify that the Dow-Jones Industrial Average index indeed follows this scaling. We then focus on two popular stochastic volatility models, the Heston and Hull-White models. In particular, we show that in the Hull-White model the resulting probability distribution of log-returns in this approximation corresponds to the Tsallis (t-Student) distribution. The Tsallis parameters are given in terms of the microscopic stochastic volatility model. Finally, we show that the log-returns for 30 years Dow Jones index data is well fitted by a Tsallis distribution, obtaining the relevant parameters. (c) 2007 Elsevier B.V. All rights reserved.

Adjunctive benefits of systemic etoricoxib in non-surgical treatment of aggressive periodontitis: Short-term evaluation

Background: This pilot study assessed the effect of short-duration treatment with etoricoxib as adjuvant therapy to scaling and root planing (SRP) on the clinical and radiographic parameters and prostaglandin E-2 (PGE(2)) levels in aggressive periodontitis. Methods: Subjects were randomly allocated to test or control treatment (n = 10 in each group) and submitted to SRP and treatment with etoricoxib, 120 mg/day, or placebo for 7 days. Probing depth, clinical attachment level (CAL), gingival recession, visible plaque index, bleeding on probing, linear distance (LD) from the cemento-enamel junction to the alveolar crest, and analysis of the gray levels were recorded before and 1 month after the therapies. The prostaglandin E-2 (PGE(2)) level in the gingival crevicular fluid (GCF) was measured by radioimmunoassay at the beginning of the study and 7 and 30 days after treatment. Results: No significant difference in the clinical parameters was observed between the groups at the end of the experimental period, although both groups presented significant improvement in all variables examined. There was a decrease in CAL from 5.54 +/- 0.47 mm to 3.59 +/- 0.53 mm in the test group and from 5.92 +/- 1.10 mmto 3.69 +/- 0.80 mm in the control group. A significant reduction in PGE(2) was found after 7 days of treatment. LD differed between the groups. Conclusion: Etoricoxib did not promote additional improvement in the clinical parameters; however, it produced an initial reduction in the PGE(2) levels in the GCF, which could be related to the discrete improvement in the bone condition.

Antimicrobial Photodynamic Therapy in the Non-Surgical Treatment of Aggressive Periodontitis: Cytokine Profile in Gingival Crevicular Fluid, Preliminary Results

Background: Aggressive periodontitis is a specific form of periodontal disease that is characterized by rapid attachment loss and bone destruction. Cytokine profiles are of considerable value when studying disease course during treatment. The aim of this trial was to investigate cytokine levels in the gingival crevicular fluid (GCF) of patients with aggressive periodontitis, after treatment with photodynamic therapy (PDT) or scaling and root planing (SRP), in a split-mouth design on -7, 0, +1, +7, +30, and +90 days. Methods: Ten patients were randomly treated with PDT using a laser source associated with a photosensitizer or SRP with hand instruments. GCF samples were collected, and the concentrations of tumor necrosis factor-alpha (TNF-alpha) and receptor activator of nuclear factor-kappa B ligand (RANKL) were determined by enzyme-linked immunosorbent assays. The data were analyzed using generalized estimating equations to test the associations among treatments, evaluated parameters, and experimental times (alpha = 0.05). Results: Non-surgical periodontal treatment with PDT or SRP led to statistically significant reductions in TNF-alpha level 30 days following treatment. There were similar levels of TNF-alpha and RANKL at the different time points in both groups, with no statistically significant differences. Conclusion: SRP and PDT had similar effects on crevicular TNF-alpha and RANKL levels in patients with aggressive periodontitis. J Periodontol 2009;80:98-105.

Liquid-liquid equilibria for systems composed of refined soybean oil, free fatty acids, ethanol, and water at different temperatures

Soybean oil can be deacidified by liquid-liquid extraction with ethanol. In the present paper, the liquid-liquid equilibria of systems composed of refined soybean oil, commercial linoleic acid, ethanol and water were investigated at 298.2 K. The experimental data set obtained from the present study (at 298.2 K) and the results of Mohsen-Nia et al. [1] (at 303.2 K) and Rodrigues et al. [2] (at 323.2 K) were correlated by applying the non-random two liquid (NRTL) model. The results of the present study indicated that the mutual solubility of the compounds decreased with an increase in the water content of the solvent and a decrease in the temperature of the solution. Among variables, the water content of the solvent had the strongest effect on the solubility of the components. The maximum deviation and average variance between the experimental and calculated compositions were 1.60% and 0.89%, indicating that the model could accurately predict the behavior of the compounds at different temperatures and degrees of hydration. (C) 2010 Elsevier B.V. All rights reserved.

FORCED CONVECTION TO LAMINAR FLOW OF LIQUID EGG YOLK IN CIRCULAR AND ANNULAR DUCTS

The steady-state heat transfer in laminar flow of liquid egg yolk - an important pseudoplastic fluid food - in circular and concentric annular ducts was experimentally investigated. The average convection heat transfer coefficients, determined by measuring temperatures before and after heating sections with constant temperatures at the tube wall, were used to obtain simple new empirical expressions to estimate the Nusselt numbers for fully established flows at the thermal entrance of the considered geometries. The comparisons with existing correlations for Newtonian and non-Newtonian fluids resulted in excellent agreement. The main contribution of this work is to supply practical and easily applicable correlations, which are, especially for the case of annulus, rather scarce and extensively required in the design of heat transfer operations dealing with similar shear-thinning products. In addition, the experimental results may support existing theoretical analyses.