Characterization of bacteriocins produced by two strains of Lactobacillus plantarum isolated from Beloura and Chouriço, traditional pork products from Portugal

Bacteriocins bacST202Ch and bacST216Ch, produced by Lactobacillus plantarum strains isolated from Beloura and Chouriço, respectively, inhibited the growth of a number of Gram-positive and Gram-negative meat spoilage bacteria. According to trycine–SDS–PAGE, bacST202Ch and bacST216Ch are approximately 3.5 and 10.0 kDa in size, respectively. Maximal activity of bacST202Ch (25,600 AU/ml) was recorded after 27 h of and bacST216Ch (102,400 AU/ml) after 22 h of growth. The mode of activity, as determined against Enterococcus faecium HKLHS, is bactericidal. Both peptides adsorb to the surface of the producer cells, but at very low concentrations. Both peptides remained active after 120 min at 100 ^oC and after 2 h of incubation at pH 2.0–12.0. Treatment for 120 min at 121 ^oC did not affect bacST216Ch activity. Activity of bacST202Ch and bacST216Ch was not affected by 1% Triton X-100, Tween 80, Tween 20, SDS, NaCl, urea and EDTA. Bacteriocin ST216Ch was deactivated in the presence of 1% Triton X-114. The nucleotide sequence of a 1044 bp DNA fragment amplified from L. plantarum ST202Ch is identical to the structural gene encoding pediocin PA-1, suggesting that the two bacteriocins are identical. Based on the broad spectrum of antibacterial activity, strains ST202Ch and ST216Ch may be used as starter cultures in the fermentation of meat products.     

Polarization Holographic Gratings

Abstract

The photoinduced anisotropy (dichroism and birefringence) in AgCl emulsions is studied as well as the possibility for chemical fixing of this anistropy. A theoretical relation between the diffraction efficiency of amplitude—phase polarization holographic gratings and the photoanisotropy of the recording medium is derived. Based on this relationship an estimation of the properties of the gratings is presented. Polarization holographic gratings with spatial frequencies of 200 to 2000 mm^?1 and diffraction efficiency up to 1·8% are recorded. The gratings are stable, and do not change in time for more than a year.     

Drivers for High Power Laser Diodes

1 Introduction High power laser diodes (HPLD) usually have more than 10 W CW output optical power, or more than 20 W peak power for more than 1 s pulse duration. When we talk about HPLD, we shall not distinguish be- tween single stripe emitters, or linear bars, or bar stacks. From this point, three main groups of HPLD ac- cording to their design and applications may be catego- rized. The first group includes continuous CW HPLD, consisting of one or several linear bars, fiber coupled i…     

On the construction of <Emphasis Type="Italic">q</Emphasis>-ary equidistant codes

The problem of constructing equidistant codes over an alphabet of an arbitrary size q is considered. Some combinatorial constructions and computer-based search methods are presented. All maximal equidistant codes with distances 3 and 4 are found.     

Infinite Markov jump-bounded real lemma

A bounded real lemma is established, providing an equivalent condition to stochastic stability (SS) of a continuous-time infinite Markovian jump linear system (MJLS) with a prescribed L₂-stochastic disturbance attenuation level γ in terms of existence of solutions to an infinite set of coupled linear matrix inequalities (LMIs). Besides the interest in its own right, the main result provides a fundamental tool for the development of an H_∞-like theory devoted to this class of systems.     

Iterative linearization methods for approximately optimal control and estimation of non-linear stochastic system

This paper presents an iterative Linear-Quadratic-Gaussian method for locally-optimal control and estimation of non-linear stochastic systems. The new method constructs an affine feedback control law, obtained by minimizing a novel quadratic approximation to the optimal cost-to-go function, and a non-adaptive estimator optimized with respect to the current control law. The control law and filter are iteratively improved until convergence. The performance of the algorithm is illustrated on a complex biomechanical control problem involving a stochastic model of the human arm.     

Shared perceptual basis of emotional expressions and trustworthiness impressions from faces.

Using a dynamic stimuli paradigm, in which faces expressed either happiness or anger, the authors tested the hypothesis that perceptions of trustworthiness are related to these expressions. Although the same emotional intensity was added to both trustworthy and untrustworthy faces, trustworthy faces who expressed happiness were perceived as happier than untrustworthy faces, and untrustworthy faces who expressed anger were perceived as angrier than trustworthy faces. The authors also manipulated changes in face trustworthiness simultaneously with the change in expression. Whereas transitions in face trustworthiness in the direction of the expressed emotion (e.g., high-to-low trustworthiness and anger) increased the perceived intensity of the emotion, transitions in the opposite direction decreased this intensity. For example, changes from high to low trustworthiness increased the intensity of perceived anger but decreased the intensity of perceived happiness. These findings support the hypothesis that changes along the trustworthiness dimension correspond to subtle changes resembling expressions signaling whether the person displaying the emotion should be avoided or approached. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Studies on the possibility for genetic recombination in Streptomyces flavopersicus

The Epstein-Barr virus nuclear antigen 2 (EBNA2) gene is thought to be important for transformation by Epstein-Barr virus (EBV), but the mechanism of this transformation is little understood. Here, to examine the transforming ability of EBNA2, we transfected a rat fibroblast cell line F2408 with a recombinant EBNA2 expression plasmid and examined cell morphology, colony formation in soft agar, and tumorigenicity in nude mice. The morphology of transfected clones was similar to those of untransfected cells, but two of seven clones grew in soft agar, and four clones of seven clones reproducibly formed tumors in nude mice. These four clones showed EBNA2 expression, but non-tumorigenic clones did not. These results indicate that the expression of EBNA2 is correlated with tumorigenicity.