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排序方式: 共有2030条查询结果,搜索用时 156 毫秒
971.
Cristiano V.M. Araújo Victoria Tornero Julián Blasco Pedro Cañavate Dora Franco Ana Bartual Rui Ribeiro Amparo Torreblanca Ignacio Moreno-Garrido 《The Science of the total environment》2010,408(4):822-828
This work presents the results of an interlaboratory proficiency exercise for whole-sediment toxicity assays with the benthic marine diatom Cylindrotheca closterium. An assay protocol was established and followed by all participating laboratories. Cell growth after 72 h exposure was the endpoint used. Four sediment samples of unknown toxicity were assayed. The main problem encountered during this exercise was the differences in the cell growth of algae exposed to reference sediment. Those differences may be associated with changes in the physiological status of the initial culture due to temperature changes during transport to the other laboratories. In general, the method proposed presented good replicability (precision between replicates) and reproducibility (interlaboratory precision). Around 80% (17 out of 21) of results obtained were classified as satisfactory (Z-scores < 2). The whole-sediment assay with C. closterium presented here can be considered sufficiently successful for possible use as a standard toxicity test. The assay is simple to perform, the proposed species is ecologically relevant as an integral component of microphytobenthos, and is widely distributed around the world. These positive factors suggest that the whole-sediment assay with the benthic marine diatom C. closterium can be used as a reliable tool in marine sediment quality assessment. 相似文献
972.
Dantas-Santos N Gomes DL Costa LS Cordeiro SL Costa MS Trindade ES Franco CR Scortecci KC Leite EL Rocha HA 《International journal of molecular sciences》2012,13(1):961-976
Sulfated polysaccharides (SP) are found mainly in seaweeds and animals. To date, they have only been found in six plants and all inhabit saline environments. Furthermore, there are no reports of SP in freshwater or terrestrial plants. As such, this study investigated the presence of SP in freshwaters Eichhornia crassipes, Egeria densa, Egeria naja, Cabomba caroliniana, Hydrocotyle bonariensis and Nymphaea ampla. Chemical analysis identified sulfate in N. ampla, H. bonariensis and, more specifically, E. crassipes. In addition, chemical analysis, FT-IR spectroscopy, histological analysis, scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDXA), as well as agarose gel electrophoresis detected SP in all parts of E. crassipes, primarily in the root (epidermis and vascular bundle). Galactose, glucose and arabinose are the main monosaccharides found in the sulfated polysaccharides from E. crassipes. In activated partial thromboplastin time (APTT) test, to evaluate the intrinsic coagulation pathway, SP from the root and rhizome prolonged the coagulation time to double the baseline value, with 0.1 mg/mL and 0.15 mg/mL, respectively. However, SP from the leaf and petiole showed no anticoagulant activity. Eichornia SP demonstrated promising anticoagulant potential and have been selected for further studies on bioguided fractionation; isolation and characterization of pure polysaccharides from this species. Additionally in vivo experiments are needed and are already underway. 相似文献
973.
974.
Characterisation of a laboratory electrochemical ozonation system and its application in advanced oxidation processes 总被引:1,自引:0,他引:1
Leonardo M. Da Silva Débora V. Franco Juliane C. Forti Wilson F. Jardim Julien F.C. Boodts 《Journal of Applied Electrochemistry》2006,36(5):523-530
An electrochemical reactor for oxygen/ozone production was developed using perforated planar electrodes. An electroformed
-PbO2 coating, deposited on a platinised titanium substrate, was employed as anode while the cathode was a platinised titanium substrate. The electrodes were pressed against a solid polymer electrolyte to minimise ohmic drop and avoid mixing of the gaseous products (H2 and O2/O3). Electrochemical ozone production (EOP) was investigated as function of current density, temperature and electrolyte composition. Electrochemical characterisation demonstrated ozone current efficiency, ΦEOP, ozone production rate (g h−1),
, and grams of O3 per total energy demand (g h−1 W−1), increase on decreasing electrolyte temperature and increasing current density. The best reactor performance for EOP was obtained with the base electrolyte (H2SO4 3.0 mol dm−3) containing 0.03 mol dm−3 KPF6. Degradation of reactive dyes used in the textile industry (Reactive Yellow 143 and Reactive Blue 264) with electrochemically-generated ozone was investigated in alkaline medium as function of ozone load (mg h−1) and ozonation time. This investigation revealed ozonation presents very good efficiency for both solution decolouration and total organic carbon (TOC) removal. 相似文献
975.
Multimode interference tapered fiber refractive index sensors 总被引:1,自引:0,他引:1
Real-time monitoring of the fabrication process of tapering down a multimode-interference-based fiber structure is presented. The device is composed of a pure silica multimode fiber (MMF) with an initial 125?μm diameter spliced between two single-mode fibers. The process allows a thin MMF with adjustable parameters to obtain a high signal transmittance, arising from constructive interference among the guided modes at the output end of the MMF. Tapered structures with waist diameters as low as 55?μm were easily fabricated without the limitation of fragile splices or difficulty in controlling lateral fiber alignments. The sensing device is shown to be sensitive to the external environment, and a maximum sensitivity of 2946 nm/refractive index unit in the refractive index range of 1.42-1.43 was attained. 相似文献
976.
977.
Franco Sandrolini 《Cement and Concrete Composites》2012,34(3):306-312
Despite the widespread use of ethyl silicate for stone consolidation, the investigation of its reactivity with the different supports is still in progress. In this paper, the pozzolanic behaviour of ethyl silicate is investigated, by means of experimental mixtures of commercial ethyl silicate and slaked lime, and the occurrence of C-S-H formation is shown. The ability of ethyl silicate to penetrate in porous building materials as a liquid solution and, only after curing, to give rise to a pozzolanic material encourages the application of ethyl silicate for the consolidation and protection of reinforced concrete, as well as for the consolidation of modern cement-based mortars having artistic value (Art Nouveau cement-based mortars, etc.). The pozzolanic effect of ethyl silicate can be exploited also for the formulation of new consolidating materials (e.g. with nanolime). 相似文献
978.
Filomena Pinto Rui Neto André Carlos Franco Helena Lopes Carlos Carolino Ricardo Costa Ibrahim Gulyurtlu 《Fuel》2010,89(11):3340-54
Coal mixed with different types of wastes was co-gasified in a pilot-scale installation. The syngas produced was hot treated in two catalytic fixed-bed reactors. In the first one, dolomite was used and in the second reactor, a nickel-based catalyst was employed. Two different grade coals were tested, Puertollano and Colombian. Puertollano coal had high ash and sulphur contents, 42.5% and 2.4%, respectively, while ash and sulphur contents of Colombian coal were, respectively, 12.7% and 0.9%. Pine, bagasse, RDF and PE were the wastes mixed with both coals. After dolomite fixed-bed reactor, H2S and NH3 contents in syngas were much lower than those of the gas leaving the gasifier. For most coal and waste blends, NH3 reductions changed between 30% and 50% depending on feedstock nitrogen content, while H2S reductions achieved values from 68% to 74%, also depending on H2S concentration in syngas. After syngas had gone through the nickel-based catalyst, it presented H2S and NH3 contents that allowed its use in boilers and gas engines for most coal and waste blends. The overall syngas treatment led to H2S and NH3 reductions higher than 97%. For most experiments, final H2S and NH3 concentration in syngas were below 20 ppmv and 30 ppmv, respectively. 相似文献
979.
980.
Existing jet penetration correlations have all been developed for sub‐sonic gas jets and have been found to perform poorly when employed in sonic and supersonic regimes. In the present study, triboelectric probes were used to measure both the penetration depth and expansion angle of sonic gas jets. Experiments were conducted using nozzles of different size and geometry, different particle types, different injection gases, and different fluidization velocities. All these data were used to develop a new, general correlation to predict the penetration depth of sonic gas jets. The effects of these variables on jet expansion angle were also studied. 相似文献