Birefringence enhancement by using D-shaped microstructured optical fibers

In this study, a detailed numerical investigation is presented, seeking to enhance the birefringence effect by using D-shaped microstructured optical fibers (MOFs). We studied a D-shape core geometry associated with three different air-hole configurations: circular and elliptical, aligned with either the x-direction or the y-direction. Results have shown that ultrahigh birefringence MOFs, with B values of the order of 10(-2) for a wide range of wavelengths, can be obtained. The highest birefringence B was equal 3.97 x 10(-2), a value found for a D-MOF (circular holes) at 1550 nm. To the best of our knowledge, this is the highest theoretical value in the published literature.

Chemical-mineralogical characterization of C&D waste recycled aggregates from Sao Paulo, Brazil

This study presents a methodology for the characterization of construction and demolition (C&D) waste recycled aggregates based on a combination of analytical techniques (X-ray fluorescence (XRF), soluble ions, semi-quantitative X-ray diffraction (XRD), thermogravimetric analysis (TCA-DTG) and hydrochloric acid (HCl) selective dissolution). These combined analytical techniques allow for the estimation of the amount of cement paste, its most important hydrated and carbonated phases, as well as the amount of clay and micas. Details of the methodology are presented here and the results of three representative C&D samples taken from the Sao Paulo region in Brazil are discussed. Chemical compositions of mixed C&D aggregate samples have mostly been influenced by particle size rather than the visual classification of C&D into red or grey and geographical origin. The amount of measured soluble salts in C&D aggregates (0.15-25.4 mm) is lower than the usual limits for mortar and concrete production. The content of porous cement paste in the C&D aggregates is around 19.3% (w/w). However, this content is significantly lower than the 43% detected for the C&D powders (< 0.15 min). The clay content of the powders was also high, potentially resulting from soil intermixed with the C&D waste, as well as poorly burnt red ceramic. Since only about 50% of the measured CaO is combined with CO(2), the powders have potential use as raw materials for the cement industry. (C) 2008 Elsevier Ltd. All rights reserved.

Fate of Surface-Inoculated Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium on Kippered Beef during Extended Storage at Refrigeration and Abusive Temperatures

The behavior of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium on kippered beef was evaluated. Individual pieces of the product were separately inoculated on the top and bottom surfaces with each three- to six-strain pathogen cocktail at ca. 6.0 log CFU per piece and stored at 4, 10, 21, or 30 degrees C for up to 28 days in each of two trials. When kippered beef was inoculated with E coli O157:H7, Salmonella Typhimurium, or L. monocytogenes and stored at 4, 10, 2 1, or 30 degrees C for up to 28 days, pathogen numbers decreased ca. 0.4 to 0.9, 1.0 to 1.8, 3.0 to >= 5.25, and >= 5.0 to 5.25 log CFU per piece, respectively. Average D-values for E. coli O157:H7, Salmonella Typhimurium, and L. monocytogenes stored at 4 to 30 degrees C for 28 days were ca. 41 to 4.6, 40.8 to 5.3, and 29.5 to 4.3 days, respectively. As expected, the higher the storage temperature, the greater the level and rate of inactivation for all three pathogens. These data establish that kippered beef does not provide an environment conducive to proliferation of these pathogens.

Paracoccin from Paracoccidioides brasiliensis; purification through affinity with chitin and identification of N-acetyl-beta-D-glucosaminidase activity

The dimorphic fungus Paracoccidioides brasiliensis is the causative agent of paracoccidioidomycosis, the most frequent systemic mycosis in Latin America. Our group has been working with paracoccin, a P. brasiliensis lectin with MM 70 kDa. which is purified by affinity, with immobilized N-acetylglucosamine (GlcNAc). Paracoccin has been described to play a role in fungal adhesion to extracellular matrix components and to induce high and persistent levels or TNF alpha. and nitric oxide production by macrophages. In the cell wall, paracoccin colocalizes with the beta-1,4-homopolymer of GlcNAc into the budding sites of the P. brasiliensis yeast cell. In this paper we present a protocol for the chitin-affinity purification or paracoccin. This procedure provided higher yields than those achieved by means of the technique based oil the affinity of this lectin with GlcNAc and had an impact on downstream assays. SDS-PAGE and Western blot analysis revealed similarities between the N-acetylglucosamine- and chitin-bound fractions, confirmed by MALDI-TOF-MS of trypsinic peptides. Western blot of two-dimensional gel electrophoresis of the yeast extract showed a major spot with M(r) 70000 and pl approximately 5.63. Moreover, an N-acetyl-beta-D-glucosaminidase activity was reported for paracoccin, thereby providing new insights into the mechanisms that lead to cell wall remodelling and opening new perspectives for its structural characterization. Copyright (C) 2009 John Wiley & Sons. Ltd.