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11.
Uuve Kirso Priit Alumaa Natalya Irha Valter Petersell Erik Teinemaa Jörgen Slet 《Polycyclic Aromatic Compounds》2013,33(1-4):55-66
Two typical Estonian soils, Brown pseudopodzolic and Rendzina, were used for sorption studies with pyrene. The soil samples were subjected to a variety of chemical and physical tests. The specific surface area reached 3.05 m2 g?1 for Rendzina, and 0.87 m2 g?1 for Brown pseudopodzolic soil. The Rendzina type of soil was characterized also by a high organic matter content (22.9%) compared with the Brown pseudopodzolic soil (6.64%). A batch technique was used to perform all adsorption studies. Koc values 2.7 × 104 mg g?1 for Rendzina and 4.5 × 104 mg g?1 for Brown pseudopodzolic were obtained. The results suggets that pyrene sorption behaviour could be in some instances mainly influenced by the composition of organic compounds in the soil, not so much by the overall organic matter content. Also the mineral part of the soil can have a impact to pyrene sorption through Ca-binded humic substances. 相似文献
12.
From the 1980's onwards, specific requirements of standard guidelines related to failure analysis have made it necessary to extensively apply nonlinear numerical models for containment safety assessment. In the same period new structure types have been proposed which reveal high sensitivities to load cases reproducing accident conditions. This paper presents the results of preliminary non linear calculations on simplified models. The results point out how load conditions with different contribution of temperature loads respect to pressure can lead to large variations in failure mechanisms and limit load factors. This uncertainty is related to the poor definition of accident scenarios and stresses the need for seeking a general agreement on simulation criteria to be used in safety evaluations in order to obtain fully understandable and comparable results. 相似文献
13.
Minella M Rogora M Vione D Maurino V Minero C 《The Science of the total environment》2011,409(18):3463-3471
A model-based approach is here developed and applied to predict the long-term trends of indirect photochemical processes in the surface layer (5 m water depth) of Lake Maggiore, NW Italy. For this lake, time series of the main parameters of photochemical importance that cover almost two decades are available. As a way to assess the relevant photochemical reactions, the modelled steady-state concentrations of important photogenerated transients (•OH, 3CDOM* and CO3-•) were taken into account. A multivariate analysis approach was adopted to have an overview of the system, to emphasise relationships among chemical, photochemical and seasonal variables, and to highlight annual and long-term trends. Over the considered time period, because of the decrease of the dissolved organic carbon (DOC) content of water and of the increase of alkalinity, a significant increase is predicted for the steady-state concentrations of the radicals •OH and CO3−•. Therefore, the photochemical degradation processes that involve the two radical species would be enhanced. Another issue of potential photochemical importance is related to the winter maxima of nitrate (a photochemical •OH source) and the summer maxima of DOC (•OH sink and 3CDOM* source) in the lake water under consideration. From the combination of sunlight irradiance and chemical composition data, one predicts that the processes involving •OH and CO3−• would be most important in spring, while the reactions involving 3CDOM* would be most important in summer. 相似文献
14.
Valter Sergo Chiara Schmid Patrizio Accardo Sergio Meriani 《Journal of the American Ceramic Society》1993,76(5):1377-1380
An experimental arrangement capable of monitoring temperature changes from 0.01 to 0.1 K has been successfully tested for registering the temperature evolution occurring during the tetragonal to monoclinic transformation of an alumina/ceria-stabilized tetragonal zirconia polycrystal (Al2 O3 /Ce-TZP). The arrangement is based on a very small thermistor. The data obtained have been used for evaluating the thermal diffusivity of the Al2 O3 /Ce-TZP composites. 相似文献
15.
Structure control, coating properties, and durability of fluorinated acrylic-based polymers 总被引:1,自引:0,他引:1
Valter Castelvetro Mauro Aglietto Francesco Ciardelli Oscar Chiantore Massimo Lazzari Lucia Toniolo 《Journal of Coatings Technology》2002,74(928):57-66
Fluorinated acrylates were employed for the synthesis of conventional, side-chain fluorinated, fully acrylic random copolymers,
and of more unusual hybrid copolymers with vinyl ethers. The latter can feature alternating structure and peculiar material
properties associated with fluorine or fluorinated groups substitution onto the polymer backbone. Improved efficacy and durability
of the resulting coating, highly desirable for the consolidation and protection of highly valued works of art, was achieved
through a systematic approach involving a detailed study of their photodegradation behavior, and extensive testing of protection
efficacy upon application onto micro-and macroporous stone substrates of different chemical composition and morphology.
Presented on behalf of FATIPEC (AITIVA) at the 78th Annual Meeting of the FSCT in Chicago, IL on October 16–20, 2000.
Dipartimento di Chimica e Chimica Industriale, Via Risorgimento 35, 56126 Pisa, Italy.
Dipartimento di Chimica IFM, via Pietro Giuria 7, 10125 Torino, Italy.
Piazza Leonardo da Vinci 32, 20133 Milano, Italy, Lucia. 相似文献
16.
Luzia Shundo Adriana P. de Almeida Janete Alaburda Leda C.A. Lamardo Sandra A. Navas Valter Ruvieri Myrna Sabino 《Food Control》2009,20(12):1099-1102
Seventy paprika samples collected in the city of São Paulo, Brazil, from January to April 2006 were analysed for aflatoxins and ochratoxin A (OTA) using an immunoaffinity column clean-up and HPLC-FLD. For aflatoxins, the limit of quantification (LOQ) were 0.23, 0.23, 0.45 and 0.45 μg/kg for AFB1, AFB2, AFG1 and AFG2, respectively. For OTA the LOQ was 0.80 μg/kg. Aflatoxins were found in 82.9% of samples and AFB1 was detected in 61.4% at levels ranging from 0.5 to 7.3 μg/kg with mean concentration of 3.4 μg/kg. OTA was found in 85.7% at levels ranging from 0.24 to 97.2 μg/kg with mean concentration of 7.0 μg/kg. 相似文献
17.
Amon S. L. Ribeiro Anelyse Arata Nelson B. de Lima Valter Ussui Dolores R. R. Lazar 《International Journal of Applied Ceramic Technology》2019,16(5):2020-2027
Conventional sintering techniques of yttria-tetragonal zirconia polycrystals (Y-TZP) ceramics have presented limitations regarding the sintering time and temperature, increasing the cost of the final dental and biomedical products. Herein, microwave sintering comes to be an interesting alternative by providing fast heating, high densification, and grain-size control. The aim of this study was to compare the effect of microwave sintering of Y-TZP dental ceramics prepared from a pre-sintered commercial block and produced from powders synthesized in a laboratorial scale by the precipitation route. The synthetized and commercial discs were submitted to microwave sintering at 1450°C and 1350°C for 15, 30, and 60 minutes. Densification, fracture toughness, grain size, and crystalline phase quantification of the sintered groups were evaluated. Both synthetized and commercial groups sintered at 1450°C for 15 and 30 minutes showed the higher densification results (98% TD). XRD quantitative phase analysis indicates that samples present 89% tetragonal and 11% cubic phases, except for the group prepared from coprecipitated powders sintered at 1450°C for 30 minutes, that presented 79% and 21% of tetragonal and cubic phases. The microwave sintering at 1450°C allows hardness and fracture toughness values comparable to conventional sintering. 相似文献
18.
Ruth U Barbante C Bigler M Delmonte B Fischer H Gabrielli P Gaspari V Kaufmann P Lambert F Maggi V Marino F Petit JR Udisti R Wagenbach D Wegner A Wolff EW 《Environmental science & technology》2008,42(15):5675-5681
To improve quantitative interpretation of ice core aeolian dust records, a systematic methodological comparison was made. This involved methods for water-insoluble particle counting (Coulter counter and laser-sensing particle detector), soluble ion analysis (ion chromatography and continuous flow analysis), elemental analysis (inductively coupled plasma mass spectroscopy at pH 1 and after full acid digestion), and water-insoluble elemental analysis (proton induced X-ray emission). Antarctic ice core samples covering the last deglaciation from the EPICA Dome C (EDC) and the EPICA Dronning Maud Land (EDML) cores were used. All methods correlate very well among each other, but the ratios of glacial age to Holocene concentrations, which are typically a factor approximately 100, differ between the methods by up to a factor of 2 with insoluble particles showing the largest variability. The recovery of ICP-MS measurements depends on the digestion method and is differentfor different elements and during different climatic periods. EDC and EDML samples have similar dust composition, which suggests a common dust source or a common mixture of sources for the two sites. The analyzed samples further reveal a change of dust composition during the last deglaciation. 相似文献
19.
Valter Crescenzi Alvaro A. A. Fernandes Paolo Merialdo Norman W. Paton 《Knowledge and Information Systems》2017,50(1):1-26
The discovery of informative itemsets is a fundamental building block in data analytics and information retrieval. While the problem has been widely studied, only few solutions scale. This is particularly the case when (1) the data set is massive, calling for large-scale distribution, and/or (2) the length k of the informative itemset to be discovered is high. In this paper, we address the problem of parallel mining of maximally informative k-itemsets (miki) based on joint entropy. We propose PHIKS (Parallel Highly Informative \(\underline{K}\)-ItemSet), a highly scalable, parallel miki mining algorithm. PHIKS renders the mining process of large-scale databases (up to terabytes of data) succinct and effective. Its mining process is made up of only two efficient parallel jobs. With PHIKS, we provide a set of significant optimizations for calculating the joint entropies of miki having different sizes, which drastically reduces the execution time, the communication cost and the energy consumption, in a distributed computational platform. PHIKS has been extensively evaluated using massive real-world data sets. Our experimental results confirm the effectiveness of our proposal by the significant scale-up obtained with high itemsets length and over very large databases. 相似文献
20.
Henryk Tomaszewski Jan Strzeszewski Lech Adamowicz Valter Sergo 《Journal of the American Ceramic Society》2002,85(11):2855-2857
A method is proposed for the indirect determination of the stress dependence (expressed as piezospectroscopic (PS) coefficients) of spectroscopic bands of ceramic materials/phases. This method is based on the intimate mixture (intimate at the microstructural, grain-size level) of two phases/materials when the stress in one is independently known; it is used to determine the PS coefficients of the most intense Raman bands in ceria-stabilized tetragonal zirconia polycrystals (Ce-TZP). Different amounts of Ce-TZP were mixed with alumina and the composite pellets sintered; subsequently, the stress in alumina was determined through the PS coefficient of its R2 luminescence band and the stress in Ce-TZP derived from the static equilibrium condition. The frequency shifts of each Raman band of Ce-TZP have been plotted against the stress and the slopes provide the PS coefficients. The method has the advantage of not requiring any type of loading device (i.e., diamond anvil-cell, bending jig). Finally, the limits are also discussed, the most important one being the requirement of immiscibility of the two materials/phases. 相似文献