Ionization and Structural Changes of the DMPG Vesicle along Its Anomalous Gel-Fluid Phase Transition: A Study with Different Lipid Concentrations

Dispersions of saturated anionic phospholipid dimyristoyl phosphatidylglycerol (DMPG) have been extensively studied regarding their peculiar thermostructural behavior. At low ionic strength, the gel-fluid transition is spread along nearly 17 degrees C, displaying several thermal events in the calorimetric profile that is quite different from the single sharp peak around 23 degrees C found for higher ionic strength DMPG dispersions. To investigate the role of charge in the bilayer transition, we carefully examine the temperature dependence of the electrical conductivity of DMPG dispersions at different concentrations, correlating the data with the corresponding differential scanning calorimetry (DSC) traces. Electrical conductivity together with electrophoretic mobility measurements allowed the calculation of the dependence of the degree of ionization of DMPG vesicles on lipid concentration and temperature. It was shown that there is a decrease in vesicle charge as the lipid concentration increases, which is probably correlated with the increase in the concentration of bulk Na(+). Apart from the known increase in the electrical conductivity along the DMPG temperature transition region, a sharp rise was observed at the bilayer pretransition for all lipid concentrations studied, possibly indicating that the beginning of the chain melting process is associated with an increase in bilayer ionization. It is confirmed here that the gel-fluid transition of DMPG at low ionic strength is accompanied by a huge increase in the dispersion viscosity. However, it is shown that this measured macroviscosity is distinct from the local viscosity felt by either charged ions or DMPG charged aggregates in measurements of electrical conductivity or electrophoretic mobility, Data presented here give support to the idea that DMPG vesicles, at low ionic strength, get more ionized along the temperature transition region and could be perforated and/or deformed vesicle structures.

Phototransformation of hematoporphyrin in aqueous solution: Anomalous behavior at low oxygen concentration

The photoactivation of a photosensitizer is the initial step in photodynamic therapy (PDT) where photochemical reactions result in the production of reactive oxygen species and eventually cell death. In addition to oxidizing biomolecules, some of these photochemical reactions lead to photosensitizer degradation at a rate dependent on the oxygen concentration among other factors. We investigated photodegradation of Photogem A (R) (28 mu M), a hematoporphyrin derivative, at different oxygen concentrations (9.4 to 625.0 mu M) in aqueous solution. The degradation was monitored by fluorescence spectroscopy. The degradation rate (M/s) increases as the oxygen concentration increases when the molar ratio of oxygen to PhotogemA (R) is greater than 1. At lower oxygen concentrations (< 25 mu M) an inversion of this behavior was observed. The data do not fit a simple kinetic model of first-order dependence on oxygen concentration. This inversion of the degradation rate at low oxygen concentration has not previously been demonstrated and highlights the relationship between photosensitizer and oxygen concentrations in determining the photobleaching mechanism(s). The findings demonstrate that current models for photobleaching are insufficient to explain completely the effects at low oxygen concentration.

Anomalous content of chromium in a Cretaceous sandstone aquifer of the Bauru Basin, state of Sao Paulo, Brazil

Anomalous and natural concentrations of Cr(6+), occasionally exceeding the permitted limit for human consumption (0.05 mg/L), have been detected in groundwater in the northwestern region of the state of Sao Paulo. As part of a water-rock interaction investigation, this article describes the chemical and mineralogical characterization of rock samples taken from boreholes in the municipality of Urania, with the objective of identifying Cr-bearing minerals and determining how chromium is associated with these minerals. Rock sample analysis were performed using X-ray Fluorescence, X-ray Diffraction, Scanning Electron Microscopy, electron microprobe and sequential extraction techniques. Chemical analyses indicated that the quartzose sandstones show a geochemical anomaly of chromium, with an average content of 221 ppm, which is higher than the reported chromium content of generic sandstones (35 ppm). Diopside was identified as the primary Cr-bearing mineral potentially subject to weathering processes, with a chromium content of up to 1.2% as Cr(2)O(3). Many of the diopside grains showed dissolution features, confirming the occurrence of weathering. Sequential extraction experiments indicated that 99.3% of the chromium in samples is tightly bonded to minerals, whereas 0.24% is weakly bonded via adsorption. Assuming hypothetically that all adsorbed chromium is released via desorption, the theoretical Cr concentration in water would be one order of magnitude higher than the concentrations of Cr(6+) detected in groundwater. (C) 2010 Elsevier Ltd. All rights reserved.

Anomalous spin-related quantum phase in mesoscopic hole rings

We have obtained numerically exact results for the spin-related geometric quantum phases that arise in p-type semiconductor ring structures. The interplay between gate-controllable (Rashba) spin splitting and quantum-confinement-induced mixing between hole-spin states causes a much higher sensitivity of magnetoconductance oscillations to external parameters than previously expected. Our results imply a much-enhanced functionality of hole-ring spin-interference devices and shed new light on recent experimental findings.

On anomalous diffusion and the fractional generalized Langevin equation for a harmonic oscillator

The fractional generalized Langevin equation (FGLE) is proposed to discuss the anomalous diffusive behavior of a harmonic oscillator driven by a two-parameter Mittag-Leffler noise. The solution of this FGLE is discussed by means of the Laplace transform methodology and the kernels are presented in terms of the three-parameter Mittag-Leffler functions. Recent results associated with a generalized Langevin equation are recovered.

Structural aspects of the fermion-boson mapping in two-dimensional gauge and anomalous gauge theories with massive fermions

Using a synthesis of the functional integral and operator approaches we discuss the fermion-buson mapping and the role played by the Bose field algebra in the Hilbert space of two-dimensional gauge and anomalous gauge field theories with massive fermions. In QED, with quartic self-interaction among massive fermions, the use of an auxiliary vector field introduces a redundant Bose field algebra that should not be considered as an element of the intrinsic algebraic structure defining the model. In anomalous chiral QED, with massive fermions the effect of the chiral anomaly leads to the appearance in the mass operator of a spurious Bose field combination. This phase factor carries no fermion selection rule and the expected absence of Theta-vacuum in the anomalous model is displayed from the operator solution. Even in the anomalous model with massive Fermi fields, the introduction of the Wess-Zumino field replicates the theory, changing neither its algebraic content nor its physical content. (C) 2002 Elsevier B.V. (USA).

Particular solution for anomalous diffusion equation with source term

In literature the phenomenon of diffusion has been widely studied, however for nonextensive systems which are governed by a nonlinear stochastic dynamic, there are a few soluble models. The purpose of this study is to present the solution of the nonlinear Fokker-Planck equation for a model of potential with barrier considering a term of absorption. Systems of this nature can be observed in various chemical or biological processes and their solution enriches the studies of existing nonextensive systems.

Anomalous quartic gauge boson couplings at hadron colliders

We analyze the potential of the Fermilab Tevatron and CERN Large Hadron Collider (LHC) to study anomalous quartic vector-boson interactions gamma gamma ZZ and gammaW(+)W(-). Working in the framework of SU(2)(L) circle times U(1)(Y) chiral Lagrangians, we study the production of photon pairs accompanied by l(+) l(-), l(+/-) v, and jet pairs to impose bounds on these new couplings, taking into account the unitarity constraints. We compare our findings with the indirect limits coming from precision electroweak measurements as well as with presently available direct searches at CERN LEPII. We show that the Tevatron run II can provide limits on these quartic limits which are of the same order of magnitude as the existing bounds from LEPII searches. LHC will be able to tighten considerably the direct constraints on these possible new interactions, leading to more stringent limits than the presently available indirect ones.

Searching for anomalous Higgs couplings in peripheral heavy ion collisions at the LHC

We investigate the sensitivity of the heavy ion mode of the LHC to anomalous Higgs boson couplings to photons, H gamma gamma, through the analysis of the processes gamma gamma --> b (b) over bar and gamma gamma --> gamma gamma in peripheral heavy ion collisions. We suggest cuts to improve the signal over background ratio and determine the capability of LHC to impose bounds on anomalous couplings by searching for a Higgs boson signal in these modes. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Limits on anomalous trilinear gauge couplings from WW -> e(+)e(-), WW -> e(+/-)mu(-/+), and WW ->mu(+)mu(-) events from pp collisions at root s=1.96 TeV

Limits are set on anomalous WW gamma and WWZ trilinear gauge couplings using W+W--> e(+)nu(e)e(-)(nu) over bar (e), W+W--> e(+/-)nu(e)mu(-/+)nu(mu), and W+W-->mu(+)nu(mu)mu(-)(nu) over bar (mu) events. The data set was collected by the Run II D0 detector at the Fermilab Tevatron Collider and corresponds to approximately 250 pb(-1) of integrated luminosity at root s=1.96 TeV. Under the assumption that the WW gamma couplings are equal to the WWZ couplings and using a form factor scale of Lambda=2.0 TeV, the combined 95% C.L. one-dimensional coupling limits from all three channels are -0.32

Electric charge quantization and the muon anomalous magnetic moment

We investigate some proposals to solve the electric charge quantization puzzle that simultaneously explain the recent measured deviation on the muon anomalous magnetic moment. For this we assess extensions of the electro-weak standard model spanning modifications on the scalar sector only. It is interesting to verify that one can have modest extensions which easily account for the solution for both problems.

Search for anomalous heavy-flavor quark production in association with W bosons

We search for anomalous production of heavy-flavor quark jets in association with W bosons at the Fermilab Tevatron p(p) over bar Collider in final states in which the heavy-flavor quark content is enhanced by requiring at least one tagged jet in an event. Jets are tagged using one algorithm based on semileptonic decays of b/c hadrons, and another on their lifetimes. We compare e+jets (164 pb(-1)) and mu+jets (145 pb(-1)) channels collected with the D0 detector at root s = 1.96 TeV to expectations from the standard model and set upper limits on anomalous production of such events.

Z gamma production and limits on anomalous ZZ gamma and Z gamma gamma couplings in pp collisions at root s=1.96 TeV

We present a study of eey and mu mu gamma events using 1109 (1009) pb-(1) of data in the electron (muon) channel, respectively. These data were collected with the DO detector at the Fermilab Tevatron pp collider at Is = 1.96 TeV. Having observed 453 (515) candidates in the eey (jtAy) final state, we measure the Z gamma production cross section for a photon with transverse energy ET > 7 GeV, separation between the photon and leptons Delta Rey > 0.7, and invariant mass of the di-lepton pair Mee > 30 GeV/(2)(c), to be 4.96 0.30(stat. + syst.) zE 0.30(lumi.) pb, in agreement with the Standard Model prediction of 4.74 0.22 pb. This is the most precise Zy cross section measurement at a hadron collider. We set limits on anomalous trilinear Zyy and ZZy gauge boson couplings of -0.085 < h(30)(y) < 0.084, -0.0053 < h(40)(y) < 0.0054 and -0.083 < h(30)(Z) < 0.082, 30 40 30 -0.0053 < h(40)(Z) < 0.0054 at the 95% C.L. for the form-factor scale A = 1.2 TeV. 40 Published by Elsevier B.V.

Measurement of the pp(-)-> W gamma plus X cross section at root s=1.96 TeV and WW gamma anomalous coupling limits

The WW gamma triple gauge boson coupling parameters are studied using p (p) over bar -> l nu gamma + X(l = e, mu) events at root s = 1.96 TeV. The data were collected with the D0 detector from an integrated luminosity of 162 pb(-1) delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for p (p) over bar -> W(gamma) + X -> l nu gamma + X with E-T(gamma) > 8 GeV and Delta R-l gamma > 0.7 is 14.8 +/- 1.6(stat) +/- 1.0(syst) +/- 1.0(lum) pb. The one-dimensional 95% confidence level limits on anomalous couplings are -0.88 < Delta kappa(gamma) < 0.96 and -0.20 < lambda(gamma) < 0.20.

Production of WZ events in pp(-) collisions at root s=1.96 TeV and limits on anomalous WWZ couplings

We present results from a search for WZ production with subsequent decay to l nu l'(l) over bar'(l and l' = e or mu) using 0.30 fb(-1) of data collected by the D0 experiment between 2002 and 2004 at the Fermilab Tevatron. Three events with WZ decay characteristics are observed. With an estimated background of 0.71 +/- 0.08 events, we measure the WZ production cross section to be 4.5(-2.6)(+3.8) pb, with a 95% C.L. upper limit of 13.3 pb. The 95% C.L. limits for anomalous WWZ couplings are found to be -2.0