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91.
Mihajlidi-Zelić A Dersek-Timotić I Relić D Popović A Dordević D 《The Science of the total environment》2006,370(2-3):441-451
The region of the investigated receptor is situated in the southern part of the Adriatic Sea in the Mediterranean. The measuring station is located on the seashore, which, being considered as a border area, is representative for the qualitative and quantitative estimation of the influence of marine and continental aerosols on the content of major ions in precipitation. In the sampling period, precipitation in the region of the investigated receptor was more abundant during the summer and autumn than during the winter and spring. The most frequent precipitation heights were up to 20 mm, while high precipitation came exclusively from the continental region. The results of the measurements of ions readily soluble in water were used for the differentiation of marine from continental contributions of primary and secondary aerosols to their content in the precipitation. Using PCA, it was shown that main contribution of Cl(-), Na(+) and Mg(2+) came from primary marine aerosols, while the contribution from continental sources was dominant for the content of SO(4)(2-), NO(3)(-), NH(4)(+) and Ca(2+) in the precipitation. The continental origin of Ca(2+) was from a primary source, while SO(4)(2-), NO(3)(-) and NH(4)(+) were representatives of secondary aerosols produced by reactions between acid oxides and alkaline species in the atmosphere, but SO(4)(2-) and NO(3)(-) also exist in the precipitation as free acids. The origin of the trace elements Cd, Cu, Pb and Zn in the precipitation came from anthropogenic emission sources. The results obtained in this work are based on experimental data from 609 samples collected during the period 1995-2000. 相似文献
92.
The determination of radon-prone areas is usually based on indoor radon data and on the prognosis of the occurrence of houses exceeding the action level. However, the sample of houses in the survey must be representative and large enough, which is not easy to fulfill. Despite this, the determination of localities with high radon risk is useful not only for planning of indoor radon surveys, but also mainly for predicting the risk in newly built houses. There exist two more sources of data that can be used when assigning radon-related index to territories: soil gas radon measurements and gamma dose rate maps, both having their own inaccuracies. An attempt has been made to combine Czech indoor radon data, soil gas radon data and gamma dose rate maps for municipalities, where available. The radon-related index has been constructed by means of statistical analysis (linear regression). The equations found can be used for predicting the radon risk of the municipalities where the data sets are not large enough. 相似文献
93.
Ivana Radosavljevic Evans Judith A.K. HowardTatjana Sreckovic Momcilo M. Ristic 《Materials Research Bulletin》2003,38(7):1203-1213
The effect of mechanical activation on formation of calcium titanate (CaTiO3) from calcined mixtures of CaCO3 and TiO2 was studied by monitoring the course of this solid-state reaction by variable temperature in situ X-ray diffraction (XRD) experiments, scanning electron microscopy (SEM) and dilatometry. Two equimolar mixtures of powdered CaCO3 and TiO2 were prepared: one was mechanically activated by grinding in a high energy vibro-mill. A total of 32 X-ray diffraction data sets for each sample, collected between 30 and 1100 °C, were analyzed by multiphase Rietveld refinement. Quantitative phase analysis and microstructure analysis obtained from X-ray diffraction are correlated to results of scanning electron microscopy and dilatometry. In the non-activated sample, small quantities of the reactants remain in the product until 1100 °C. In the activated sample, the reaction results in pure CaTiO3 at 920 °C. 相似文献
94.
Peng H Gu Z Liu Y Chiang IW Smalley RE Hauge RH Khabashesku VN Margrave JL 《Journal of nanoscience and nanotechnology》2003,3(1-2):87-92
The chemical stability of fluoronanotubes in selected solid inorganic matrixes has been studied by initially mixing and mechanically grinding the components and subsequently heating them at temperatures ranging from 35 to 600 degrees C. The inorganic compounds selected for matrixes included halides (KBr, KI, Lil, LiBr, LiCl, NaCl, Znl2), oxides (Li2O, Fe2O3, PbO, MnO), lithium peroxide (Li2O2), potassium superoxide (KO2), sulfides (Li2S and ZnS), zinc selenide (ZnSe), lithium nitride (Li3N), and aluminum phosphide (AIP). Solid products, resulting from the proceeding chemical reactions, were analyzed by X-ray diffraction, Raman spectroscopy, and SEM/EDX elemental analysis. Gaseous and volatile products were identified with the help of the TGA/MS technique. Experimental data presented in this paper provide clear evidence that fluoronanotubes are not chemically inert toward the solid matrixes studied and exhibit significant oxidative properties in the redox reactions occurring under various temperatures, depending on the nature of the inorganic compound. 相似文献
95.
Ivana Mašić Ilija Ilić Rok Dreu Svetlana Ibrić Jelena Parojčić Stanko Srčič 《Drug development and industrial pharmacy》2014,40(1):23-32
Objective: The aim of this study was to investigate the influence of process parameters, binder content and binder addition method on characteristics of the granules obtained by melt granulation (MG) in fluidized bed.Methods: Spray-on experiments were performed according to 23 full factorial design. The effect of binder content, molten binder feed rate, and spray air pressure on granule size and size distribution, granule shape, ?owability and drug release rate was investigated. In the in situ experiments, the influence of binder particle size and binder content was evaluated. Solid-state characterization was performed by means of differential scanning calorimetry, X-ray powder diffraction and Fourier transform infrared spectroscopy.Results: Size of the granules obtained by spray-on procedure was significantly influenced by binder content and spray air pressure, while the width of particle size distribution was mainly affected by binder feed rate. Spray air pressure showed the most significant influence on granule shape. It was shown that smooth and spherical particles with good flow properties may be obtained by both procedures, spray-on and in situ MG. The results obtained indicated the influence of agglomeration mechanism on granule sphericity, with higher degree of granule sphericity observed when immersion and layering was the dominant mechanism. Paracetamol release from granulates was very rapid, but after compression of the granules into tablets, drug release was considerably slower. Solid-state analysis confirmed that the physical form of the granulate components remained unaffected after the MG process.Conclusion: The results presented indicate that MG in fluidized bed could be a good alternative to conventional granulation techniques. 相似文献
96.
Investigations were carried out on the cast samples of Cu–6.6 wt.%Ag alloy, as well as pure copper samples, for the sake of comparison. Cast samples of copper and alloy were subjected to the same thermomechanical treatment. The thermomechanical treatment included the homogenized annealing, prefinal cold rolling, solution annealing, final cold rolling with a final reduction of 20%, 40% and 60% as well as the isochronal and isothermal annealing up to the recrystallization temperature. Influence of thermomechanical treatment on the hardening mechanisms and structural changes of cast Cu–6.6 wt.%Ag alloy has been investigated for the hardness and electrical conductivity measurements as well as optical microscopy. The study has shown that the anneal hardening effect appeared on the cast Cu–6.6 wt.%Ag alloy in the temperature range of 160–400 °C and was followed by an increase in the hardness and electrical conductivity. 相似文献
97.
Bohumil Smola Luděk Joska Vítězslav Březina Ivana Stulíková František Hnilica 《Materials science & engineering. C, Materials for biological applications》2012,32(4):659-664
Conventionally cast Mg–5Y–4Rare Earth–0.5Zr alloy (WE54) was solution treated (525 °C/8 h — T4) and one part subsequently aged (200 °C/16 h — T6). Powder from the cast WE54 alloy prepared by gas atomizing was consolidated by extrusion at 250 °C or 400 °C. Dense triangular arrangement of prismatic plates of transient D019 and C-base centered orthorhombic phases precipitated in the α-Mg matrix during the T6 treatment. Both alloys prepared by powder metallurgy exhibit similar microstructure consisting of ~ 4–6 μm α-Mg matrix fibers surrounded by particles of the equilibrium Mg5(Y, Nd) phase and of oxides. Open circuit potential and polarization resistance in the isotonic saline (9 g/l NaCl/H2O) were monitored for 24 h. The corrosion rate of the T4 and T6 treated alloys was about 80 times lower than that of commercial Mg. Both alloys prepared by powder metallurgy exhibited approximately 8 times higher corrosion resistance than commercial Mg. The human MG-63 osteoblast-like cells spreading and division in the extracts (0.28 g in 28 ml of EMEM) of all 4 alloys were monitored by cinemicrography for 24 h. The MG-63 cells proliferate without cytotoxicity in all extracts. 相似文献
98.
Christian Gumpenberger Juan Gorraiz Martin Wieland Ivana Roche Edgar Schiebel Dominique Besagni Claire François 《Scientometrics》2013,95(1):277-297
Negative results are not popular to disseminate. However, their publication would help to save resources and foster scientific communication. This study analysed the bibliometric and semantic nature of negative results publications. The Journal of Negative Results in Biomedicine (JNRBM) was used as a role model. Its complete articles from 2002–2009 were extracted from SCOPUS and supplemented by related records. Complementary negative results records were retrieved from Web of Science in “Biochemistry” and “Telecommunications”. Applied bibliometrics comprised of co-author and co-affiliation analysis and a citation impact profile. Bibliometrics showed that authorship is widely spread. A specific community for the publication of negative results in devoted literature is non-existent. Neither co-author nor co-affiliation analysis indicated strong interconnectivities. JNRBM articles are cited by a broad spectrum of journals rather than by specific titles. Devoted negative results journals like JNRBM have a rather low impact measured by the number of received citations. On the other hand, only one-third of the publications remain uncited, corroborating their importance for the scientific community. The semantic analysis relies on negative expressions manually identified in JNRBM article titles and abstracts and extracted to syntactic patterns. By using a Natural Language Processing tool these patterns are then employed to detect their occurrences in the multidisciplinary bibliographical database PASCAL. The translation of manually identified negation patterns to syntactic patterns and their application to multidisciplinary bibliographic databases (PASCAL, Web of Science) proved to be a successful method to retrieve even hidden negative results. There is proof that negative results are not only restricted to the biomedical domain. Interestingly a high percentage of the so far identified negative results papers were funded and therefore needed to be published. Thus policies that explicitly encourage or even mandate the publication of negative results could probably bring about a shift in the current scientific communication behaviour. 相似文献
99.
Being aware of negative health effects of radon exposure, many countries aim for the reduction of the radon exposure of their population. The Czech radon programme was commenced >20 y ago. Since then experts have gathered a lot of knowledge, necessary legislation has been enacted, tens of thousands of inhabitants have been offered free measurement and subsidy for the mitigation. Despite the effort, the effectiveness of the radon programme seems to be poor. Newly built houses still exhibit elevated radon concentrations and the number of houses mitigated is very low. Is it possible to enhance the effectivity of radon programme while keeping it on a voluntary basis? One possible way is to employ health marketing that draws together traditional marketing theories and science-based strategies to prevention. The potential of using marketing principles in communication and delivery of radon information will be discussed. 相似文献
100.
This paper offers a comprehensive overview on the role of nanostructures in the development of advanced anode materials for application in both lithium and sodium-ion batteries. In particular, this review highlights the differences between the two chemistries, the critical effect of nanosize on the electrode performance, as well as the routes to exploit the inherent potential of nanostructures to achieve high specific energy at the anode, enhance the rate capability, and obtain a long cycle life. Furthermore, it gives an overview of nanostructured sodium- and lithium-based anode materials, and presents a critical analysis of the advantages and issues associated with the use of nanotechnology. 相似文献