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91.
A novel application of an electrochemical biosensor is here employed as analytical method for the detection and presumptive identification of antimicrobial drug residues in milk. The measurement was based on carbon dioxide production rate in relation to inhibition of microbial grow (Escherichia coli ATCC 11303). In this pilot study quinolone and tetracycline residues have been taken into consideration because use of these last in livestock production has been identified as area of particular concern. The experimental approach and analytical method developed appear adequate for the purpose, and compared to older screening methods as, for example, the microbial inhibition assays and immunoassays, offers the advantages of (i) very short analysis time (about 120 min); (ii) smaller sample amount (approximately 0.5 mL); (iii) no sample treatment (iv) good precision; and (v) the possibility of following, in a continuous manner, the inhibition process. Moreover, sensitivity of electrochemical biosensor system is resulted very high considering that for all quinolones and tetracyclines investigated it has been possible detect a residue concentration below or equal to 25 μg L−1. Under this point of view, it must be considered that the maximum residue limits fixed by UE for quinolones and tetracyclines in milk are, at present, all higher of this concentration. 相似文献
92.
Angel Bustamante Enrico Mattievich Helio S. de Amorim Ivo Vencato Máximo M. Silveira 《Hyperfine Interactions》2005,166(1-4):599-603
The crystal structure of synthetic ferrous hureaulite, Fe5 2+ (H2O)4(PO4H)2(PO4)2, was refined from single-crystal X-ray data. It is monoclinic, space group C2/c, with a=17.487(4), b=9.017(2), c=9.338(2) Å, β=96.27(3)°, V=1463.6(6) Å3, Z=4 and D calc=3.327 g/cm3. This end member of the hureaulite series was crystallized under distinctly acidic conditions, by a method that gives perfect crystals, large enough for X-ray single crystal studies. The main feature of the hureaulite structure is that it has an equal number of normal (PO4)3+ and acid (PO4H)2+ tetradentate groups. These are centered on Fe2+ atoms and share corners with edge-linked octahedra, forming pentamer units. The five Fe2+ atoms are distributed on three distinct sites in these units. This can be directly observed in the Mössbauer spectrum at 295 K, which contains three doublets whose relative intensities correspond to the 1:2:2 distributions of crystallographic sites. 相似文献
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94.
Many beautiful experiments have been addressed to test standard quantum mechanics against local realistic models. Even if a strong evidence favouring standard quantum mechanics is emerged, a conclusive experiment is still lacking, because of low detection efficiencies. Recently, experiments based on pseudoscalar mesons have been proposed as a way for obtaining a conclusive experiment. In this paper, we investigate if this result can effectively be obtained. Our conclusions, based on a careful analysis of the proposed set ups, are that this will not be possible due to intrinsic limitations of these kind of experiments. 相似文献
95.
96.
97.
M. Sangermano R. Bongiovanni G. Malucelli A. Priola J Olbrych A. Harden N. Rehnberg 《Journal of polymer science. Part A, Polymer chemistry》2004,42(6):1415-1420
The cationic photopolymerization of oxetane‐based systems containing silicon monomers was investigated. For this purpose, three new silicon‐containing oxetane monomers were synthesized through a simple and straightforward synthetic method. The silicon‐containing monomers were added to a typical oxetane resin, 3,3′‐[oxydi(methylene)]bis(3‐ethyloxetane), in concentrations of 1–5 wt %. They exploited a certain surface tension effect without affecting the rate of polymerization. Enrichment only on the air side was achieved, which induced hydrophobicity in the photocured films, depending on the monomer structure and concentration. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1415–1420, 2004 相似文献
98.
Enrico Sanjust Raffaello Pompei Antonio Rescigno Augusto Rinaldi Maoro Ballero 《Applied biochemistry and biotechnology》1991,31(3):223-235
Four species of Pleurotus were adapted to grow on olive milling wastewater, and in certain conditions produced high yield of fruit bodies. Some biochemical transformations were observed in the olive milling wastewater owing to the growth of Pleurotus. In particular, the fungi actively excreted large amounts of laccase in the medium, and at the same time the concentration of phenolics and other toxic compounds significantly decreased, as revealed by HPLC analysis and toxicity tests on standard cultures of human cell lines. 相似文献
99.
100.
Gabor Schmera Adi Bulsara David Pierson Frank Moss Enrico Di Cera 《Journal of statistical physics》1993,71(5-6):1179-1190
We consider the class of experiments which can be characterized by a Fokker-PIanck dynamics corresponding to the overdamped motion of a state point in a suitable stochastic potential. We assume that the general form of the potential is known (or can be guessed with reasonable accuracy), but that its parameters are to be determined experimentally by measurements made with a noisy instrument. This possible method for determining the potential parameters, which exploits the system's own internal stochastic motion in order to explore rapidly its available parameter space, is substantially more efficient than traditional methods involving time averages of single point measurements, and yet does not appear to have been previously considered. The method could be important when, for example, the experiment must be completed in a limited time owing either to the expense of the experimental materials or to the temporary stationarity of the preparation, situations which are commonly encountered in experimental biochemistry and biology. 相似文献