Critical behavior of self-assembled rigid rods on two-dimensional lattices: Bethe-Peierls approximation and Monte Carlo simulations.

The critical behavior of adsorbed monomers that reversibly polymerize into linear chains with restricted orientations relative to the substrate has been studied. In the model considered here, which is known as self-assembled rigid rods (SARRs) model, the surface is represented by a two-dimensional lattice and a continuous orientational transition occurs as a function of temperature and coverage. The phase diagrams were obtained for the square, triangular, and honeycomb lattices by means of Monte Carlo simulations and finite-size scaling analysis. The numerical results were compared with Bethe-Peierls analytical predictions about the orientational transition for the square and triangular lattices. The analysis of the phase diagrams, along with the behavior of the critical average rod lengths, showed that the critical properties of the model do not depend on the structure of the lattice at low temperatures (coverage), revealing a quasi-one-dimensional behavior in this regime. Finally, the universality class of the SARRs model, which has been subject of controversy, has been revisited.

Statistical thermodynamics of long straight rigid rods on triangular lattices: nematic order and adsorption thermodynamic functions.

The statistical thermodynamics of straight rigid rods of length k on triangular lattices was developed on a generalization in the spirit of the lattice-gas model and the classical Guggenheim-DiMarzio approximation. In this scheme, the Helmholtz free energy and its derivatives were written in terms of the order parameter, δ, which characterizes the nematic phase occurring in the system at intermediate densities. Then, using the principle of minimum free energy with δ as a parameter, the main adsorption properties were calculated. Comparisons with Monte Carlo simulations and experimental data were performed in order to evaluate the outcome and limitations of the theoretical model.

New isotherm for multisite occupancy adsorption of long, straight rigid rods.

The adsorption of long, straight rigid rods of length k (k-mers) on 2D lattices is described by using a new theoretical approach based on a generalization of the classical Guggenheim-DiMarzio approximation. In this scheme, the Helmholtz free energy and its derivatives are written in terms of the order parameter δ, which characterizes the nematic phase occurring in the system at intermediate densities. Then, using the principle of minimum free energy with δ as a parameter, the main adsorption properties are calculated. Comparisons with Monte Carlo simulations are performed in order to test the validity of the theoretical model. The obtained results indicate that the new thermodynamic description is significantly better than the existing theoretical models developed to treat the polymer adsorption problem.

Designing 2-aminoimidazole alkaloids analogs with anti-biofilm activities: structure-activities relationships of polysubstituted triazoles.

In order to discover novel probes that may help in the investigation and the control of bacterial biofilms, we have designed a library of triazole-based analogs of 2-aminoimidazole marine alkaloids: naamine A and isonaamine A. Twenty-two compounds were screened for their biofilm inhibitory activity against two strains of Gram-negative bacteria. Four compounds were shown to act as non-toxic inhibitors of biofilm development without effect on bacterial growth even at high concentrations (100 µM).

Fungus-bacterium associations are widespread in fungal cultures isolated from a semi-arid natural grassland in Germany.

We report on a study that aimed at establishing a large soil-fungal culture collection spanning a wide taxonomic diversity and systematically screening the collection for bacterial associations. Fungal cultures were isolated from soil samples obtained from a natural grassland in eastern Germany and bacterial associations were assessed by PCR-amplification and sequencing of bacterial 16S rRNA. In addition, intraspecies genetic diversities of a subset of the isolated species were estimated by double-digest restriction associated DNA sequencing. A total of 688 fungal cultures, representing at least 106 fungal species from 36 different families, were obtained and even though clonal isolates were identified in almost all fungal species subjected to ddRAD-seq, relatively high genetic diversities could be observed in some of the isolated species. A total of 69% of the fungal isolates in our collection were found to be associated with bacteria and the most commonly identified bacterial genera were Pelomonas, Enterobacter and Burkholderia. Our results indicate that bacterial associations commonly occur in soil fungi, even if antibiotics are being applied during the isolation process, and provide a basis for the use of our culture collection in ecological experiments that want to acknowledge the importance of intraspecies genetic diversity.

Critical behavior of self-assembled rigid rods on triangular and honeycomb lattices.

Using Monte Carlo simulations and finite-size scaling analysis, the critical behavior of self-assembled rigid rods on triangular and honeycomb lattices at intermediate density has been studied. The system is composed of monomers with two attractive (sticky) poles that, by decreasing temperature or increasing density, polymerize reversibly into chains with three allowed directions and, at the same time, undergo a continuous isotropic-nematic (IN) transition. The determination of the critical exponents, along with the behavior of Binder cumulants, indicate that the IN transition belongs to the q=1 Potts universality class.

Phase diagram of self-assembled rigid rods on two-dimensional lattices: theory and Monte Carlo simulations.

Monte Carlo simulations and finite-size scaling analysis have been carried out to study the critical behavior in a two-dimensional system of particles with two bonding sites that, by decreasing temperature or increasing density, polymerize reversibly into chains with discrete orientational degrees of freedom and, at the same time, undergo a continuous isotropic-nematic (IN) transition. A complete phase diagram was obtained as a function of temperature and density. The numerical results were compared with mean field (MF) and real space renormalization group (RSRG) analytical predictions about the IN transformation. While the RSRG approach supports the continuous nature of the transition, the MF solution predicts a first-order transition line and a tricritical point, at variance with the simulation results.

CLA-producing adjunct cultures improve the nutritional value of sheep cheese fat.

The influence of the autochthonous CLA-producing Lactobacillus plantarum TAUL 1588 and Lactobacillus casei subsp. casei SS 1644 strains and the ripening time on the fatty acid (FA) content and sensory characteristics of sheep cheese were investigated. Three cheese types with different cultures and the control cheese were produced in duplicate and ripened for 8 months. 86 individual FA were determined by gas chromatography. Ripening time (2, 90, 180 and 240 days) did not have a significant effect (P > .05) on the FA content. However, the presence of both Lactobacillus CLA-producing strains led to a decrease of the saturated FA content and to 1.30, 1.19 and 1.27 times higher levels of vaccenic acid, CLA and omega-3, respectively, when compared to the control cheese. This combination allowed obtaining sheep milk cheeses with a healthier FA content, without appreciable changes on sensory characteristics. This work could be a promising approach to increase the bioactive fatty acid content of cheeses.

Critical behavior of long straight rigid rods on two-dimensional lattices: theory and Monte Carlo simulations.

The critical behavior of long straight rigid rods of length k (k-mers) on square and triangular lattices at intermediate density has been studied. A nematic phase, characterized by a big domain of parallel k-mers, was found. This ordered phase is separated from the isotropic state by a continuous transition occurring at an intermediate density theta(c). Two analytical techniques were combined with Monte Carlo simulations to predict the dependence of theta(c) on k, being theta(c)(k) proportional to k(-1). The first involves simple geometrical arguments, while the second is based on entropy considerations. Our analysis allowed us also to determine the minimum value of k (k(min) = 7), which allows the formation of a nematic phase on a triangular lattice.

Assessing potential pathogenicity of avian influenza virus: current and experimental system.

An avian influenza (AI) isolate can be classified as a high pathogenicity avian influenza (HPAI) virus based upon the results of the standard intravenous pathogenicity index test; molecular classification, which is derived by sequencing the hemagglutinin gene across the site coding for the cleavage site; or a combination. However, discordant results between the molecular classification and virulence for experimentally infected chickens have been observed with several H5 and H7 subtype AI viruses. Because the declaration of HPAI virus results in severe effects on trade for the entire country, the gap between the genetic and phenotypic markers is an important issue, and it requires us to reexamine what should be considered an HPAI virus by the Office International des Epizooties standards. To better understand and assess the true virulence of the virus, potential pathogenicity of H5 and H7 subtype AI virus isolates has been assessed by examining the plaquing efficiency of the virus in chicken embryo fibroblast cells, conducting 14-day-old embryo passage and selection system, and applying in vitro mutagenesis coupled with reverse genetics. The potential value of these complimentary methods in assessing potential pathogenicity of the AI virus is discussed.

Determination of the binding constant of indomethacin-beta-cyclodextrin complex by capillary electrophoresis: experimental optimization and temperature study.

The apparent electrophoretic mobilities of indomethacin in beta-cyclodextrin at a range of concentrations were measured directly by capillary electrophoresis. Three different linear plots and a non linear plot are proposed for the apparent binding constant calculations, based on the fact that the molar ratio of the inclusion complex was 1:1. K values obtained at 298 K were 421 M(-1) (double reciprocal fit), 488 M(-1) (x-reciprocal fit), 428 M(-1) (y-reciprocal fit) and 490 M(-1) (non linear fit). The corresponding K values at 313 K were 380 M(-1) (double reciprocal fit), 355 M(-1) (x-reciprocal fit), 366 M(-1) (y-reciprocal fit) and 339 M(-1) (non linear fit). Using the proposed methods, the binding constant of the indomethacin-beta-cyclodextrin inclusion complex can be obtained easily. The methods have been applied to obtain the values of the constant K under different experimental conditions. Under optimized conditions the K constant is temperature dependent and non-arrhenian behaviour was observed.

Real-time polymerase chain reaction for quantitative detection of histamine-producing bacteria: use in cheese production.

Biogenic amines are toxic substances that appear in foods and beverages as a result of AA decarboxylation. The enzyme histidine decarboxylase catalyzes the decarboxylation of histidine to histamine, the biogenic amine most frequently involved in food poisoning. The aim of the present work was to develop a real-time quantitative PCR assay for the direct detection and quantification of histamine-producing strains in milk and cheese. A set of primers was designed, based on the histidine decarboxylase gene sequence of different gram-positive bacteria. The results show the proposed procedure to be a rapid (total processing time < 2 h), specific and highly sensitive technique for detecting potential histamine-producing strains. Chromatographic methods (HPLC) verified the capacity of real-time quantitative PCR to correctly quantify histamine accumulation.

Effects of dynamic rotation on event-related brain potentials.

Event-related potentials were recorded during a mental rotation task. Subjects were shown pairs of letter-like shapes and were asked to make a parity judgment. The shape on the left was always in its canonical position and the shape on the right could either be in its canonical position or be a mirror image. Two variables were manipulated for the shape on the right. First, it could appear at different orientations (50 degrees , 100 degrees or 150 degrees ); second, it could be presented in a stationary position, in a dynamic congruent direction (the shape slowly rotating toward its normal upright position) or in a dynamic incongruent direction (the shape slowly rotating in the opposite direction to its normal upright position). Orientation- and direction-dependent modulations of a negative slow wave were found. For orientation, the typical amplitude effect over parietal sites was found, the amplitude becoming more negative as the rotational angle increased. For direction, the amplitude of the negative slow wave was larger for stationary and dynamic incongruent trials than for dynamic congruent trials at 100 degrees and 150 degrees . This result suggests that presentation of a stimulus in a dynamic congruent direction facilitates the mental rotation process. At 50 degrees , differences between dynamic incongruent trials and both stationary and dynamic congruent trials were found, suggesting that the incongruent movement elicits an obstructing effect over the mental rotation process. In summary, the present experiment provides new evidence in support of the idea that the amplitude modulation over the parietal cortex is a psychophysiological marker of the mental rotation process.

Effects of nefazodone on the immune system of mice.

Mice exposed to a chronic auditory stressor and treated with nefazodone (10 mg/kg/day s.c.), showed a reduction in stress-induced suppression of thymus and spleen cellularity, and in peripheral T-Iymphocyte population. The in vitro blastogenic response of spleen lymphoid cells to mitogen concanavalin A, the in vitro and in vivo activity of phagocytosis, both measured using the zymosan and carbon clearance tests, respectively, were also assessed and nefazodone was found to partially reverse the inhibitory effect of stress on those parameters. Nefazodone did not significantly affect those parameters in unstressed mice. In conclusion, this report provides evidence on the immunoprotective effects of this novel antidepressant drug against the adverse effects of stress in mice.

Comment on "effect of polydispersity on the ordering transition of adsorbed self-assembled rigid rods".

The critical behavior of self-assembled rigid rods on a square lattice was recently reinvestigated by Almarza et al. [Phys. Rev. E 82, 061117 (2010)]. Based on the Binder cumulants and the value of the critical exponent of the correlation length, the authors found that the isotropic-nematic phase transition occurring in the system is in the two-dimensional Ising universality class. This conclusion contrasts with that of a previous study [López et al., Phys. Rev. E 80, 040105(R) (2009)] which indicates that the transition at intermediate density belongs to the q=1 Potts universality class. Almarza et al. attributed the discrepancy to the use of the density as the control parameter by López et al. The present work shows that this suggestion is not sufficient, and that the discrepancy arises solely from the use of different statistical ensembles. Finally, the necessity of making corrections to the scaling functions in the canonical ensemble is discussed.

Eritema multiforme asociado a herpes virus: reporte de caso / Erythema multiform associated with herpes virus: case report

El eritema multiforme (EM) es una reacción de hipersensibilidad que afecta a la piel y / oa las membranas mucosas, en respuesta a infecciones, fármacos u otras comorbilidades. La presentación de EM puede ser Menor (EM leve, caracterizada por presentar lesiones diana) o Mayor (EM severa, que también ocurre con afectación de las membranas mucosas). Se presenta el caso de un paciente varón de 36 años de edad que presenta una emergencia de HNAL con fiebre, malestar, prurito y lesiones dolorosas en la cavidad oral, lesiones múltiples en miembros superiores e inferiores, pene y región perianal. El diagnóstico fue EM Major. Las lesiones ulcerosas en la cavidad oral y las lesiones diana en las manos fueron las más destacadas.

Erythema multiforme (EM) is a hypersensitivity reaction that affects the skin and/or mucous membranes, in response to infections, drugs, or other comorbidities. Presentation of EM can be Minor (Mild EM, characterized for presenting target lesions) or Major (Severe EM, that occurs also with mucous membranes involvement). The case of a 36 year old male patient presenting to emergency of HNAL with fever, malaise, itching and painful ulcer type lesions in oral cavity, multiple target lesions in upper and lower limbs, penis, and perianal region is reported. The diagnosis was EM Major. Ulcerous lesions in oral cavity and target lesions in hands were the most salient.

Critical exponents and universality for the isotropic-nematic phase transition in a system of self-assembled rigid rods on a lattice.

Monte Carlo simulations have been carried out for a system of monomers on square lattices that, by decreasing temperature or increasing density, polymerize reversibly into chains with two allowed directions and, at the same time, undergo a continuous isotropic-nematic (IN) transition. The results show that the self-assembly process affects the nature of the transition. Thus, the calculation of the critical exponents and the behavior of Binder cumulants indicate that the universality class of the IN transition changes from two-dimensional Ising-type for monodisperse rods without self-assembly to q=1 Potts-type for self-assembled rods.

Alcohol-related advertisements in a college newspaper.

The college newspaper is a powerful socializing force on the university campus. Within the general context of a university-based Alcohol Abuse Prevention Project, the present investigation examined alcohol related advertising in a college newspaper at one southern university. Ads were categorized into those: (1) promoting the responsible use of alcohol, (2) promoting the irresponsible use of alcohol, and (3) having a neutral content. Results indicated that a great deal of alcohol-related advertising was presented in this publication, and the majority of advertising did not promote responsible use of the beverage. The potential role of the community-oriented professional as an intervention strategist is discussed.

Role of methylene blue-treated or fresh-frozen plasma in the response to plasma exchange in patients with thrombotic thrombocytopenic purpura.

Twenty patients with thrombotic thrombocytopenic purpura (TTP) underwent plasma exchange using either standard fresh-frozen plasma (Group A, n = 13) or methylene blue-treated plasma (Group B, n = 7). Both groups presented similar characteristics except that bilirubin values were higher in Group A (P < 0.05). The complete remission rate was higher in Group A than B (69% versus 57%). The mean number of procedures was higher in Group B (21 +/- 7 versus 11 +/- 3, P < 0.01) and the mean duration of hospitalization was also longer (37 +/- 12 d versus 22 +/- 11 d; P < 0.01). Our study shows that the use of methylene blue-treated fresh-frozen plasma to treat TTP is associated with a higher number of plasma exchanges and greater transfusion requirements without improving clinical results.