Field and temperature dependence of magnetization in FeCu-based amorphous alloys

In this paper, the production of FeCu-based FeCuZr amorphous alloys by ball milling is reported. The thermal dependence of magnetization for the [Fe_(0.5)Cu_(0.5)]_85Zr_(15) (at. %) amorphous alloy has been found to show a dramatic field dependence of the kink point of the magnetization. This kink corresponds to a temperature different from the Curie temperature, above 400 K, of the ferromagnetic phase, which, according to spin waves fitting, can be induced by applying external fields. Just above 235 K, the thermoremanence increases sharply, and this feature strongly suggests an increase of the ferromagnetic ordering under zero field heating. Neutron diffraction experiments seem to confirm the enhancement of spin alignment. The thermal expansion above the compensation temperature is proposed to be the origin of the thermoremanence enhancement through the anti-Invar effect as might be explained within the framework of recent ab initio calculations [M. van Schilfgaarde et al., Nature (London) 400, 46 (1999)]

Resistencia a biocidas de diferentes cepas de escherichia coli

Los biocidas son herramientas de gran importancia para controlar la transmisión de microorganismos patógenos a través de la cadena alimentaria. En el presente estudio se ha determinado la resistencia a siete biocidas en una colección de nueve cepas de Escherichia coli, incluyendo cepas verotoxigénicas y cepas portadoras de resistencia a beta-lactámicos. Los biocidas más eficaces fueron triclosan, hexadecilpiridinio y cetrimida, seguido del cloruro de benzalconio. No se encontraron diferencias significativas entre las cepas verotoxigénicas y/o productoras de beta lactamasas de amplio espectro en cuanto a sensibilidad a los biocidas mencionados.Biocides have great relevance in the control of transmission of foodborne microbes through the food chain. In the present study, resistance to seven biocides was investigated among a collection of nine Escherichia coli strains, including verotoxigenic and beta-lactamase producers. The most effective biocides were triclosan, hexadecylpyridinium chloride and cetrimide, followed by benzalkonium chloride. Verotoxigenic and beta-lactamase producing strains did not show significant differences in their sensitivities to biocides compared to the other strains tested

Bioconservación de alimentos cárnicos

Las bacteriocinas, así como las cepas bacterianas que las producen, han sido ampliamente estudiadas para la conservación de los alimentos por métodos naturales (bioconservación). En productos cárnicos (abarcando toda la gama, desde la materia prima hasta productos elaborados) se han desarrollado numerosos estudios empleando bacteriocinas como nisina, pediocinas y otras, bien solas o aplicadas con otros antimicrobianos (como ácidos orgánicos o agentes quelantes) o tratamientos (como el calor, las altas presiones o la luz pulsada) para la inactivación de bacterias patógenas o alterantes. Los resultados de muchos de estos tratamientos son bastante prometedores, como por ejemplo el empleo de bacteriocinas como recubrimientos protectores en salchichas. Las cepas de bacterias lácticas seleccionadas por su capacidad productora de bacteriocinas ofrecen buenas perspectivas como cultivos protectores, pero sobre todo como cultivos iniciadores en la elaboración de productos cárnicos fermentados, mejorando la seguridad microbiológica de los mismos. El empleo de cultivos iniciadores bacteriocinogénicos con propiedades funcionales definidas abre nuevas vías para la innovación y el desarrollo de nuevos productos cárnicos fermentados.Bacteriocins as well as their producer strains have been widely investigated for application in natural food preservation processes (biopreservation). Numerous studies have been carried out on application of bacteriocins such as nisin, pediocin and others in different types of meat products, either singly or in combination with other antimicrobials (such as organic acids or chelating agents) or treatments (such as heat, pulsed light or high hydrostatic pressure). Many of the results reported are highly promising, like for example the application of bacteriocins in edible coatings for sausages. Bacteriocin-producing lactic acid bacteria are also interesting, in view of their possible applications as protective cultures or as starter cultures in fermented meat products, increasing the product safety. Bacteriocin-producing starter cultures with additional functional properties open new possibilities for innovation and development of new fermented meat products

Search for Deeply Bound Kaonic Nuclear States with AMADEUS

We briefly report on the search for Deeply Bound Kaonic Nuclear States with AMADEUS in the Sigma0 p channel following K- absorption on 12C and outline future perspectives for this work

Magnetic behavior of metastable fcc Fe-Cu after thermal treatments

A ferromagnetic and supersaturated fcc Fe_51Cu_49 solid solution has been obtained by mechanical alloying. After subsequent thermal treatments the fcc phase undergoes a spinodal decomposition which finally, at 780 K, yields a mixture of fcc and bcc phases. In this work, a systematic magnetic study is carried out on samples at diferent decomposition states in order to determine the process of transformation into the stable phases. We observe a 20% maximum diminution on the magnetic moment with increasing temperatures of the thermal treatment. The Mössbauer spectrum taken at 8 K shows that 20% of the Fe atoms are in a nonferromagnetic state. On the other hand, upon heating up to 723 K the roomtemperature coercive field increases dramatically to 640 Oe, and after cooling down to 10 K it decreases to 270 Oe. Deviations from the T law in the temperature dependence of the magnetization have been observed. This behavior is explained by fluctuations in composition due to the spinodal decomposition, which lead to fluctuations of the magnetic order parameters, i.e., magnetic moment and Curie temperature

Resistencia a biocidad en cepas de Salmonella SP. aisladas de huevo

Se ha estudiado la presencia de presuntas salmonelas en la superficie de huevos comerciales, y se ha determinado la sensibilidad a biocidas para la colección de cepas ensayadas. El porcentaje de muestras positivas osciló entre el 37% y el 43%. En algunas de las marcas comerciales analizadas no se logró aislar la bacteria en los huevos analizados, mientras que en los huevos de comercios pequeños o granjas se aisló en todas las muestras ensayadas. La mayoría de las cepas fueron inhibidas a una concentración del 0.1% de los biocidas cloruro de benzalconio, cetrimida, hexadecilpiridinio, hexaclorofeno, polihexametil biguanidio o P3 oxonia. Sin embargo, en algunos casos (cetrimida, polihexametil biguanidio o P3 oxonia ) se encontró un bajo porcentaje de cepas que requerían concentraciones de biocida de hasta diez veces superiores para su inhibición. El triclosan mostró una mayor eficacia, inhibiendo al 77% de las cepas a una concentración de 0.075%. Sin embargo, el resto de las cepas fueron muy tolerantes a este biocida, siendo necesaria una concentración del 1% para su inhibición. Los resultados de este estudio sugieren la existenciaWe have studied the presence of presumptive salmonellae in comercial eggs, and the biocide tolerance of isolates. Presumptive salmonellae were detected in some 37 to 43% of samples tested. Some comercial brands were free of the bacterium, but all eggs from local stores and farms tested positive. Most isolates were inhibited by 0.1% of the biocides benzalkonium chloride, cetrimide, hexadecylpyridinium chloride, hexachlorophene, polyhexamethylen biguanide and P3 oxonia. A small percentage of isolates required up to ten-fold higher biocide concentrations for inhibition (as in the case of cetrimide, polyhexamethylen biguanide and P3 oxonia). Triclosan was apparently more effective, inhibiting 77% of isolates at 0.075%. However, the remaining of isolates only were inhibited at 1% of the biocide. Results from this study suggest that a low percentage of the Salmonella population on egg surfaces can tolerate biocides

First measurement of the K−n →Λπ−non-resonant transition amplitude below threshold

We present the analysis of K−absorption processes on He4 leading to Λπ−final states, measured with the KLOE spectrometer at the DAΦNE e+e−collider and extract, for the first time, the modulus of the non-resonant K−n →Λπ−direct production amplitude about 33 MeV below the K‾N threshold. This analysis also allows to disentangle the K−nuclear absorption at-rest from the in-flight capture, for K−momenta of about 120 MeV. The data are interpreted with the help of a phenomenological model, and the modulus of the non-resonant K−n →Λπ−amplitude for K−absorption at-rest is found to be |AK−n→Λπ−|=(0.334±0.018stat−0.058+0.034syst)fm

Erratum: Permanent magnetism, magnetic anisotropy, and hysteresis of thiol-capped gold nanoparticles (vol 93, art no 087204, 2004)

© American Physical SocietyDepto. de Física de MaterialesFac. de Ciencias FísicasTRUEpu