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Andréa C.K. Bierhalz Mariana A. da Silva Mara E.M. Braga Hermínio J.C. Sousa Theo G. Kieckbusch 《LWT》2014
The preparation of alginate films with suitable properties requires a two-step contact with reticulating agents: initially a weakly structured pre-film is formatted which is further crosslinked in a second stage by immersion in a more concentrated solution. The present work evaluated the effects of a combined crosslinking procedure using calcium and barium ions on the physical and morphological properties of alginate-based films containing natamycin as antimicrobial agent. The release behavior of natamycin in water was evaluated as well as the antimicrobial activity against four target microorganisms, which are common cheese product contaminants. Films attributes were affected by the type of ion used in the second stage while the natamycin release rate and the antimicrobial activity were influenced by the ion used in the first stage. Films crosslinked with Ba2+ in the first and Ca2+ in the second stage (Ba–Ca films) exhibited physical properties very similar to films crosslinked with calcium in both stages. Release kinetics of natamycin in water fitted well to Fick's second law diffusional model, with effective diffusivity values ranging from 0.40 × 10−11 to 1.74 × 10−11 cm2/s. Ba–Ca films presented the lowest natamycin diffusion coefficient and the smallest inhibition zone diameter against the four microorganisms tested. 相似文献
43.
A. Yildiz D. Crisan N. Dragan N. Iftimie D. Florea D. Mardare 《Journal of Materials Science: Materials in Electronics》2011,22(9):1420-1425
0.5 wt% Pd-doped titanium oxide thin films were obtained by dip-coating on silicon substrates. The films were compacted by
annealing in air at 300 and 500 °C. Temperature dependent electrical conductivity measurements were performed in the temperature
range 373–623 K, in different environments (air, methane, acetone, ethanol, formaldehyde and liquefied petroleum gas), to
test the films sensing gas properties. Formaldehyde was found to be the test gas that produces the most significant changes
in the electrical conductivity of the studied films. This was the reason why it was chosen to investigate its effect on their
electrical conductivity. A model was proposed, the model of the potential fluctuations at grain boundaries. A comparison between
some parameters obtained in the proposed model was performed as a function of annealing temperature, and as a function of
gas atmosphere. The values of the mean barrier height and the standard deviation were estimated to range between 0.336–0.588 eV
and 0.175–0.199 eV, respectively. It was found that formaldehyde leads to a rather sharp decrease in the values of the barrier
height and the standard deviation, and to an increase in the conductivity. We have observed the best sensing gas performance
for the films annealed at 300 °C, comparing to their counterparts annealed at 500 °C, explained by the lowest values of the
barrier energy height and the standard deviation. 相似文献
44.
Ana Paula R. Harbach Mara C.R. da Costa Adriana L. Soares Ana M. Bridi M. Shimokomaki Caio A. da Silva Elza I. Ida 《Food chemistry》2007,100(4):1630-1633
The effects of dietary defatted corn germ meal (DCGM) containing phytic acid (PA) on pig health during development and on its Longissimus dorsi m. (LD) lipid oxidative stability has been evaluated. Rations of DCGM were prepared at the level of substitution of 0%, 10%, 20% and 40% and offered to twenty four animals of Landrace x Large White crossbreds throughout 25 days before slaughtering. Animals were sacrificed at an average weight of 91.24 kg (±0.950) and samples for meat lipid oxidation analysis were taken after seven days under refrigeration at 3 °C. Animals fed with DCGM did not show any significant difference, in comparison to the control, in carcass characteristics, such as cold carcass weight, backfat depth, muscle depth, lean meat percentage and carcass dress yielding (p 0.05). Finally, no difference in meat proximate chemical composition was detected solely arising from lipid oxidation since LD from DCGM-treated pigs revealed an inhibition of 63.0%. 相似文献
45.
AR Linde S Sánchez-Galán JI Izquierdo P Arribas E Mara?ón E García-Vázquez 《Canadian Metallurgical Quarterly》1998,40(1-2):120-125
Brown trout (Salmo trutta L.) is a native fish of the rivers of northern Spain. It is the dominant fish species in these rivers, and it is widespread over all the range of freshwater ecosystems in the area, including ecosystems potentially polluted with heavy metals. In this study, the potential of brown trout as biomonitor of heavy metal pollution and the effect of fish age on the reliability of the assessment are analyzed. Copper, lead, and cadmium concentrations of both abiotic compartments (water and sediments) and brown trout (S. trutta) from three northern Spanish rivers were analyzed. Significant correlations were found between sediment lead content and lead concentration in trout liver. One-year-old juvenile trouts were demonstrated to be useful as a biomonitor of copper and lead pollution, revealing between-location differences. Older trouts do not seem adequate to properly monitor heavy metal pollution. The effect of aging on the reliability of this species as biomonitor is discussed. 相似文献
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Fulvio Corrandini Andrea Marchetti Mara Tagliazucchi Lorenzo Tassi Giuseppe Tosi 《加拿大化工杂志》1993,71(1):124-129
Kinematic viscosity data (ν) are presented for ethane-1,2-diol, for N, N-dimethylformamide and for nine binary mixtures in the - 10°C to 80°C temperature range. The experimental data were fitted by several empirical relations such as Grunberg-Nissan (1949), McAllister (1960), Heric (1966), Lobe (1973), Auslander (1964) and polynomial equations. Some considerations regarding the meaning of the obtained adjustment parameters are made. Furthermore, a new best fit equation is proposed and its validity has been compared to that of the other relations on the basis of the reproducibility of the experimental data. 相似文献
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