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151.
A commercially available ELISA kit was used for the detection of Bacillus diarrhoeal enterotoxin (BDE) in a variety of foods and faeces. The ability of isolates of Bacillus spp., including Bacillus cereus, to produce BDE in Brain Heart Infusion broth containing 0.1% glucose was also checked by use of the kit. Results show that 29 out of 31 B. cereus isolates were enterotoxigenic. Foods positive for performed BDE were always contaminated with > 10(5) B. cereus cfu g-1, but not all foods contaminated with large numbers of B. cereus were positive for BDE. Bacillus sp., other than one isolate which closely resembled B. subtilis, were negative for BDE production. Criteria for the confirmation of Bacillus-mediated diarrhoea should now include reports of symptoms and incubation periods consistent with the diarrhoeal form of food-poisoning by Bacillus spp., together with the results of tests for enterotoxigenicity of the Bacillus isolate, and detection of BDE in either the food and/or faeces. 相似文献
152.
F. H. S. Eleuterio L. S. Amorim H. Belich M. T. D. Orlando C. A. C. Passos J. S. Espinoza Ortiz 《Journal of Superconductivity and Novel Magnetism》2014,27(12):2679-2684
We investigate Hg 0.82Re 0.18Ba 2Ca 2Cu 3O 8.76 polycrystalline samples with an optimum oxygen content aimed to analyze both their granular composition and to measure their magnetic response. We find out that the sample corresponds to a solid solution of two intrinsic structural superconductor phases. The AC magnetic susceptibility of a powder sample with a particle size of 20 μm have a critical temperature at 133 K. To make mesoscopic-scale particles of 600 nm in size, a sample of the powder was crushed and sieved. Now, the AC magnetic sample susceptibility shows two critical temperatures at 133 and 98 K. They have been described adopting a particular parametrization of the complex scalar field associated with the order parameter in a new framework of the Ginzburg–Landau theory. Thus, we propose a microscopic model to describe the dynamical interaction between these two types of grains. 相似文献
153.
Effect of MWNTs concentration and cooling rate on the morphological,structural, and electrical properties of non‐isothermally crystallized PEN/MWNT nanocomposites
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Adriana B. Espinoza‐Martínez Carlos A. Ávila‐Orta Víctor J. Cruz‐Delgado Francisco J. Medellín‐Rodríguez Darío Bueno‐Baqués José M. Mata‐Padilla 《应用聚合物科学杂志》2015,132(14)
The effect of multiwall carbon nanotubes (MWNT) concentration and cooling rate on the morphological, structural and electrical properties of non‐isothermally crystallized Poly(ethylene naphthalate) nanocomposites (PEN/MWNT) was studied. PEN/MWNT nanocomposites containing 1 and 2 wt % of nanotubes were prepared by melt blending in a mini twin screw extruder. Nanocomposite samples with different degree of crystallinity (Xc) were obtained via non‐isothermally crystallization at cooling rates of 2, 10, 20, and 300°C min?1. In this study it was demonstrated that carbon nanotubes and cooling rate strongly influence morphological and structural characteristics of PEN. Calorimetric results showed that the peak crystallization temperature (Tc) of PEN nanocomposites was increased ~9° through heterogeneous nucleation with respect to pure PEN. X‐ray diffraction revealed that carbon nanotubes modify the crystalline structure of PEN favoring the formation of β‐crystals, and this effect increases with the nanotubes content. On the basis of X‐ray scattering analysis, the variation of lamellar thickness revealed that nanotubes promote the formation of lamellar crystals with average thickness of 20 nm at different cooling rates. These structural and morphological changes play an important role on the electrical properties of nanocomposites. It was found that higher concentration of nanotubes and crystallinity promotes electrical conductivity of nanocomposites in the order of semiconductors (until 1 × 10?4 S cm?1) as well as permittivity of 20 at different tested frequencies. This may due to the interconnected networks of nanotubes throughout the crystalline structure formed in PEN nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41765. 相似文献
154.
155.
Daylin Fernndez Pacheco Dayana Alonso Leonardo Gonzlez Ceballos Armando Zaldo Castro Sheila Brown Roldn Mairelys García Díaz Anabel Villa Testa Sarah Fuentes Wagner Janet Piloto-Ferrer Yamilet Coll García Andrs F. Olea Luis Espinoza 《International journal of molecular sciences》2022,23(15)
Colorectal cancer (CRC) is one of the most lethal cancers worldwide. If detected on time, surgery can expand life expectations of patients up to five more years. However, if metastasis has grown deliberately, the use of chemotherapy can play a crucial role in CRC control. Moreover, the lack of selectivity of current anticancer drugs, plus mutations that occur in cancerous cells, demands the development of new chemotherapeutic agents. Several steroids have shown their potentiality as anticancer agents, while some other compounds, such as Taxol and its derivatives bearing a carbamate functionality, have reached the market. In this article, the synthesis, characterization, and antiproliferative activity of four steroidal carbamates on mouse colon carcinoma CT26WT cells are described. Carbamate synthesis occurred via direct reaction between diosgenin, its B-ring modified derivative, and testosterone with phenyl isocyanate under a Brønsted acid catalysis. All obtained compounds were characterized by 1H and 13C Nuclear Magnetic Resonance (NMR), High Resolution Mass Spectroscopy (HRMS); their melting points are also reported. Results obtained from antiproliferative activity assays indicated that carbamates compounds have inhibitory effects on the growth of this colon cancer cell line. A molecular docking study carried out on Human Prostaglandin E Receptor (EP4) showed a high affinity between carbamates and protein, thus providing a valuable theoretical explanation of the in vitro results. 相似文献