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We design and manufacture the gas micropreconcentrator in low temperature cofired ceramics (LTCC) technology. The structure is 1.2-mm thick and has lateral dimensions of 25 × 20 mm. It consists of eight layers of LTCC green tapes with spiral-shaped channel filled with absorbing powder. Two heaters covered by the ceramic foils are embedded over and below the channel. The heaters are required for heating the adsorbent to elevated temperatures during its activation and desorption processes. In this paper, we describe the fabrication processes of a micropreconcentrator structure designed for acetone detection applications together with thermal and preconcentration measurements of the device. Commercially available adsorbents: Carboxen-1018, Carboxen-1012, and Carboxen-1003 from Sigma-Aldrich are selected and tested in order to concentrate low levels of acetone. The best concentration factor obtained is 5250.

Lactic starters used for cheese manufacture play an important role in the production of bitter peptides and their degradation to non-bitter products. The oligopeptide transport system (Opp) of lactococci is essential for milk peptide utilization. The periplasmic substrate binding protein serves to capture the substrate with high affinity and to deliver it to a membrane-bound complex that translocates it inside the cell. Prt+- and Lac+- derivatives of MG1363 ΔoppA strains expressing a wild-type MG1363 OppA or a mutant OppA with a single point mutation at residue 471 (OppA(D471R)) from a plasmid were constructed. These strains were used as lactic starters in cheese manufacture to improve flavour quality by removing hydrophobic peptides from the cheese matrix, through their preferential transport by OppA(D471R). Cheeses made with these strains were not significantly different from control cheeses after 1 day of ripening with respect to bacterial counts, pH and proteolysis, and only slight differences were recorded after 9 and 20 days of ripening. HPLC chromatograms of the hydrophilic and hydrophobic peptides present in the water-soluble fraction of experimental cheeses showed significant differences in peptide content as well as in peak profiles. These results suggest a different peptide utilization in the strain expressing OppA(D471R) and make it suitable for use as starter to improve cheese quality. © 2005 Elsevier B.V. All rights reserved.

A total of 253 children from two months to 12 years old, who had diarrheic or dysenteric syndromes, were studied from the rectosigmoidoscopic and parasitologic points of view. In addition, 112 and 20 of these patients were also studied bacteriologically and virologically, respectively. Only in 28 patients torphozoites of Entamoeba histolytica were found by means of direct microscopic examination, staining techniques and amoebal cultures. Enteropathogenic bacteria were isolated in 41 of the 112 cases examined. No viral particles were detected in the 20 cases studied. From the discussion of these results, the conclusion is reached that the rectosigmoidal mucusal alterations which have been currently considered as suggesting amoebal lessions are not characteristic of invasive intestinal amebiasis in children.