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71.
AbstractMetallic nanoparticles have emerged as an important class of nanomaterials for a wide range of industrial and medical applications. Because of the intensive commercial applications, risk assessment of these nanoparticles is of great importance. In the present study, the human hepatoma and leukemia cells were used to characterize the apoptotic effects of silver nanoparticles (4.7 and 42?nm) and gold nanoparticles (30?nm). Apoptotic cells were identified by chromatin condensation and flow cytometry analysis, using Annexin V/PI, TUNEL and caspase activation assays. Flow cytometry analysis showed that the three metallic nanoparticles induced apoptotic cell death in a concentration and time dependent-manner. Moreover, the three nanoparticles induced activation of caspase-3 and -7 in hepatoma and leukemia cells. Apoptotic effects were stronger after exposure of both cell lines with 4.7?nm silver nanoparticles than those obtained with 42?nm silver and 30?nm gold nanoparticles. In conclusion, silver (4.7 and 42?nm) and gold (30?nm) nanoparticles induced apoptosis in hepatoma and leukemia cells via the caspase dependent pathway. The smaller silver nanoparticles (4.7?nm) had a greater ability to induce apoptosis in both cell lines. 相似文献
72.
The objective of this work is to examine to what degree the integration between R&D and environmental departments facilitates the achievement of an environmental practice-derived competitive advantage. With this aim, we surveyed 110 International Organization for Standardization (ISO) 14001 certified factories. The results reveal that the integration of environmental action into the R&D department enhances a company's reputation through the product quality and image. Moreover, the said integration positively influences the company's overall innovative capability and, hence, its ability to penetrate international markets. 相似文献
73.
In the shrimp Crangon crangon, an important fishery resource and key species in the southern North Sea, we studied temporal variations in size, biomass
(dry weight, W) and chemical composition (C, N, protein and lipid) of eggs in an initial embryonic stage. Data from 2 years, 1996 and 2009,
consistently revealed that egg size and biomass varied seasonally, with maxima at the beginning of the reproductive season
(January), decreasing values throughout spring, minima in June–July, and a slight increase thereafter. This cyclic pattern
explains why “Winter eggs” are on average larger and heavier than “summer eggs”. Using a modelling approach, we estimated
the duration of oogenesis in relation to seasonally changing seawater temperatures. According to an additive model of multiple
explanatory variables, the C content per newly laid egg showed in both years a highly significant negative relationship with
day length (r2 = 0.38 and 0.40, respectively; P < 0.0001), a weak positive relationship with temperature (r2 = 0.08 and 0.09; P < 0.05), and a weak negative relationship with phytoplankton biomass (r2 = 0.11 and 0.12; P < 0.05) at the estimated time of beginning oogenesis. Phenotypic plasticity in initial egg size and biomass is interpreted
as an adaptive reproductive trait that has evolved in regions with strong seasonality in plankton production and periods of
larval food limitation. In contrast to biomass per egg, the percentage chemical composition remained similar throughout the
reproductive period. Both the absolute and percentage values also showed significant interannual variations, which caution
against generalizations based on short-term studies of reproductive traits of C. crangon and other species of shrimp. 相似文献
74.
BEN H. J. DE JONG MICHAEL A. CAIRNS PATRICIA K. HAGGERTY NEPTALÍ RAMÍREZ-MARCIAL SUSANA OCHOA-GAONA JORGE MENDOZA-VEGA GONZÁLEZ-ESPINOSA IGNACIO MARCH-MIFSUT 《Environmental management》1999,23(3):373-385
6 tons C were released to the atmosphere during the period of time covered by our study, equal to approximately 34% of the
1975 vegetation C pool. The Chiapas highlands, while comprising just 0.3% of Mexico's surface area, contributed 3% of the
net national C emissions. 相似文献
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77.
Héctor Miguel Aviña Jiménez Gabriel León de los Santos Miguel Ángel Benítez Torreblanca 《International Journal of Sustainable Engineering》2017,10(2):90-98
In this article, the comparison of the energetic performance of a binary cycle and a modified binary cycle with flash evaporation is presented, both using a low-enthalpy geothermal resource. The comparative analysis is based on two main discourses: the first one evaluates a conventional binary cycle (CBC) with isopentane as working fluid in order to validate and compare the generated data with those reported in similar studies; the second one uses the same input parameters for both cycles, obtaining the cases in which the modified binary cycle is the most viable choice to use. In addition to the above, several aspects are considered when selecting the most suitable working fluid, and the use of water as working fluid is introduced. When the temperature of the geothermal resource is below 140 °C, and the ambient temperature is 25 °C, the flash evaporation binary cycle, using water as working fluid, shows an improved performance compared to a CBC, with a theoretical output over 1000 kWe. This may encourage new areas of opportunity for power generation, not only with low- and medium-enthalpy geothermal energy, but also with other renewable energy sources such as solar. 相似文献
78.
Fernández-Llamazares Álvaro Garcia Raquel Amaral Díaz-Reviriego Isabel Cabeza Mar Pyhälä Aili Reyes-García Victoria 《Regional Environmental Change》2017,17(6):1673-1685
Regional Environmental Change - Existing climate data for Bolivian Amazonia rely on observations from a few sparse weather stations, interpolated on coarse-resolution grids. At the same time, the... 相似文献
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80.
M. Teresa Boquete José Bermúdez-Crespo Jesús R. Aboal Alejo Carballeira J. Ángel Fernández 《Environmental science and pollution research international》2014,21(3):2191-2200
Protein expression was assessed in samples of Pseudoscleropodium purum cross-transplanted between one unpolluted (UNP) and two polluted (POLL) sites. Firstly, the level of expression (LE) of 17 proteins differed between native mosses from both types of sites, but differences were only maintained throughout the experiment for 5 of them. The LE of these five proteins changed over time in mosses transplanted from UNP to POLL and vice versa, becoming similar to that in autotransplants. However, these changes occurred slower than changes in the heavy metal concentrations measured in the same samples, and therefore they were not related to atmospheric pollution. Although the proteins identified were associated with moss metabolism, the expected growth reduction in samples autotransplanted within POLL (as a result of the down-regulation of photosynthesis-related proteins), did not occur. This supports the hypothesis that mosses growing in polluted areas adapt to heavy metal pollution and are able to reduce/overcome their toxic effects (i.e., reduced growth). Nevertheless, further specific research must be carried out to identify the proteins involved in this type of response, as lack of information on the bryophyte genome precludes us from reaching further conclusions. 相似文献