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排序方式: 共有548条查询结果,搜索用时 15 毫秒
91.
Lactobacillus delbrueckii subsp lactis strain CIDCA 133 inhibits nitrate reductase activity of Escherichia coli 总被引:3,自引:0,他引:3
The aim of the present work was to investigate the effect of strain CIDCA 133 on the nitrate reductase activity of a non-pathogenic Escherichia coli strain. Suspensions containing different ratios of the strains under study were coincubated in MRS or MRS without glucose. In some experiments lactobacilli were killed by UV treatment. The nitrate reductase activity was determined by using a diazotization reaction for nitrite. Presence of live lactobacilli leads to a dose-response diminution in the specific nitrate reductase of E. coli even when no acidification occurred. Killing of lactobacilli by UV treatment completely abolished the anti-nitrate reductase effect. In addition, the effect was only partially observed with filtered spent culture supernatants of lactobacilli. Lactobacillus delbrueckii subsp lactis strain CIDCA 133 is able to antagonize the nitrate reductase activity of E. coli. This effect is neither due to a diminution of the viability of E. coli nor is depending on the acidification of the medium by the lactobacilli. Viability is needed for maximal anti-nitrate reductase activity. Modulation of undesirable enzymatic activities of intestinal microorganisms by means of selected microorganisms constitutes a further insight on the mechanisms by which probiotics lead to beneficial effects. Administration of probiotic strains able to modulate microbial intestinal activities could lead to a protection of the host against harmful effects of some members of the intestinal microflora. 相似文献
92.
Mediterranean diets supplemented with virgin olive oil and nuts enhance plasmatic antioxidant capabilities and decrease xanthine oxidase activity in people with metabolic syndrome: The PREDIMED study
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93.
Daniel Casellas Antoni Lara David Frómeta David Gutiérrez Sílvia Molas Lluís Pérez Johannes Rehrl Clemens Suppan 《Metallurgical and Materials Transactions A》2017,48(1):86-94
The edge fracture is considered as a high risk for automotive parts, especially for parts made of advanced high strength steels (AHSS). The limited ductility of AHSS makes them more sensitive to the edge damage. The traditional approaches, such as those based on ductility measurements or forming limit diagrams, are unable to predict this type of fractures. Thus, stretch-flangeability has become an important formability parameter in addition to tensile and formability properties. The damage induced in sheared edges in AHSS parts affects stretch-flangeability, because the generated microcracks propagate from the edge. Accordingly, a fracture mechanics approach may be followed to characterize the crack propagation resistance. With this aim, this work addresses the applicability of fracture toughness as a tool to understand crack-related problems, as stretch-flangeability and edge cracking, in different AHSS grades. Fracture toughness was determined by following the essential work of fracture methodology and stretch-flangeability was characterized by means of hole expansions tests. Results show a good correlation between stretch-flangeability and fracture toughness. It allows postulating fracture toughness, measured by the essential work of fracture methodology, as a key material property to rationalize crack propagation phenomena in AHSS. 相似文献
94.
95.
Producers, retailers and other food chain actors increasingly recognize that consumer concerns for good animal welfare represent a business opportunity that could be profitably incorporated into their commercial strategies. Therefore, during the last decade, numerous trade groups (producers, processors, retailers and restaurant chains) have developed certification systems with their suppliers which include elements of animal welfare. The Welfare Quality® project has developed an integrated and standardised welfare assessment system based on twelve welfare criteria grouped into four main principles (good feeding, good housing, good health and appropriate behaviour) according to how they are experienced by animals. One of the innovations of the Welfare Quality® assessment system is that it focuses more on outcome measures (e.g. directly related to animal body condition, health aspects, injuries, behaviour, etc.). This paper has the objective to discuss the rationale behind the welfare assessment and to describe the Welfare Quality® assessment of pigs and cattle at the slaughterhouse. 相似文献
96.
97.
Antoni Munar Andreas Sandström Shi Tang Ludvig Edman 《Advanced functional materials》2012,22(7):1511-1517
A combination of impedance spectroscopy, device characterization, and modeling is used to pinpoint key processes in the operation of polymer light‐emitting electrochemical cells (LECs). At low applied voltage, electric double layers with a thickness of ≈2–3 nm are shown to exist at the electrode interfaces. At voltages exceeding the bandgap potential of the conjugated polymer (V ≥ 2.5 V for superyellow), a light‐emitting p–n junction forms in situ, with a steady‐state structure that is found to depend strongly on the applied voltage. This is exemplified by that the effective p–n junction thickness (dpn) for a device with an interelectrode gap of 90 nm decreases from ≈23 nm at 2.5 V to ≈6 nm at 3.9 V. The current increases with decreasing dpn in a concerted manner, while the brightness reaches its peak at V = 3.4 V when dpn ≈ 10 nm. The existence of an optimum dpn for high brightness in LECs is attributed to an offset between an increase in the exciton formation rate with decreasing dpn, due to an increasing current, and a simultaneous decrease in the exciton radiative decay rate, when an increasing fraction of excitons diffuses away from the p–n junction into the surrounding non‐radiative doping regions. 相似文献
98.
Alexis Marsol-Vall Antoni Delpino-Rius Jordi Eras Mercè Balcells Ramon Canela-Garayoa 《Food Analytical Methods》2014,7(2):465-471
A fast and reliable method for the quantification of patulin using ultra high performance liquid chromatography coupled to a photodiode array detector was developed and validated for the analysis of several apple-based foodstuffs. Sample preparation was based on the QuEChERS procedure. Samples were extracted with acetonitrile and partitioned with a mixture of sodium citrate, NaCl, and Mg2SO4. The cleanup step was performed using dispersive SPE mixed with Mg2SO4 and PSA. This step was carried out twice in order to improve chromatographic results. The method was validated in spiked cloudy apple juice, apple puree, apple yogurt, beer with apple juice, and cider and applied to 24 commercial samples. The limits of detection and limits of quantification were ≥0.4 and ≥2 ng/g, respectively. Both were below the maximum legal limit established by the European Union. Recoveries for all the matrices were between 78.4 and 94.7 % while relative standard deviations were between 3.8 and 10.4 %. Patulin was detected on four apple juices from concentrate, one cloudy apple juice from an eco-store, and one beer. Nevertheless, the highest concentration found was 25.4 ng/g. 相似文献
99.
Susana Simal Antoni Femenia Juan A Crcel Carmen Rossell 《Journal of the science of food and agriculture》2005,85(3):425-432
The drying behaviour of kiwi fruits at different stage of ripeness has been evaluated. A diffusional model solved by a finite difference method has been proposed to simulate the drying kinetics at different temperatures. Drying curves of ripe kiwis exhibited only one diffusional period, whereas two different diffusional periods could be observed on the drying curves of green and half‐ripe kiwis. Furthermore, the drying curves of green and half‐ripe kiwis were coincident. The effective diffusional coefficient, which was identified at different temperatures (from 40 to 80 °C) from experimental data, varied with temperature according to the Arrhenius equation. An adequate simulation of the drying curves using the proposed model was achieved. Thus, the percentage of explained variance for the drying curves of green and half‐ripe kiwis (considering two diffusional periods) was 99.7 and 99.3% for the ripe kiwis (only one diffusional period). Regarding to the characteristics of the dried kiwis, it was observed that the colour of the samples was mainly affected by the drying temperature, whereas functional properties such as hydration and fat retention capacities were mostly influenced by the stage of ripeness of the fruit. Copyright © 2004 Society of Chemical Industry 相似文献
100.
Kakisu E Irigoyen A Torre P De Antoni GL Abraham AG 《The Journal of dairy research》2011,78(4):456-463
A two-strain starter culture containing Lactobacillus plantarum CIDCA 83114, a potential probiotic strain isolated from kefir grains, and Streptococcus thermophilus CIDCA 321 was tested for the preparation of a fermented milk product. Kluyveromyces marxianus CIDCA 8154, a yeast with immunomodulatory properties was included to formulate a three-strain starter culture. Supernatants of enterohaemorragic Escherichia coli, shiga-toxin-producing strain, along with a two-strain or a three-strain starter culture were included in the medium of Vero-cell surface cultures. The results demonstrated that these combinations of microorganisms antagonize the cytopathic action of shiga toxins. The cell concentration of Lb. plantarum did not decrease during fermentation, indicating that the viability of this strain was not affected by low pH, nor did the number of viable bacteria change during 21 days of storage in either fermented products. The number of viable yeasts increases during fermentation and storage. Trained assessors analyzed the general acceptability of fresh fermented milks and considered both acceptable. The milk fermented with the two-strain starter culture was considered acceptable after two week of storage, while the product fermented with the three-strain starter culture remained acceptable for less than one week. The main changes in sensory attributes detected by the trained panel were in sour taste, milky taste and also in fermented attributes. The correlation between different sensory attributes and acceptability indicated that the panel was positively influenced by milky attributes (taste, odour, and flavour) as well as the intensity of flavour. In conclusion, the two-strain starter culture would be the more promising alternative for inclusion of that potential probiotic lactobacillus in a fermented milk product. 相似文献