a comparative study of mechanical properties of fly ash based geopolymer made by casted and 3d printing methods

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Salicylic acid functionalized silica-coated magnetite nanoparticles for solid phase extraction and preconcentration of some heavy metal ions from various real samples

A method for the preconcentration of trace heavy metal ions in environmental samples has been reported. The presented method is based on the sorption of Cu(II), Cd(II), Ni(II) and Cr(III) ions with salicylic acid as respective chelate on silica-coated magnetite nanoparticles. Prepared adsorbent was characterized by XRD, SEM, BET and FT-IR measurements. The metals content of the sorbed complexes are eluted using 4.0 mL of 1.0 mol L-1 nitric acid. The influences of the analytical parameters including pH, amount of solid phase and condition of eluting solution, the effects of matrix ions on the retention of the analytes were examined. The accuracy and precision of suggested method were tested by analyzing of certified reference materials. The detection limits (3Sb/m, N = 8) for Cu(II), Cd(II), Ni(II) and Cr(III) ions are 0.22, 0.11, 0.27 and 0.15 μg L-1, respectively, and the maximum preconcentration factor is 200. The method was successfully applied to the evaluation of these trace and toxic metals in various waters, foods and other samples

Interferometric imaging of the type IIIb and U radio bursts observed with LOFAR on 22 August 2017

Context. The Sun is the source of different types of radio bursts that are associated with solar flares, for example. Among the most frequently observed phenomena are type III solar bursts. Their radio images at low frequencies (below 100 MHz) are relatively poorly studied due to the limitations of legacy radio telescopes. Aims. We study the general characteristics of types IIIb and U with stria structure solar radio bursts in the frequency range of 20-80 MHz, in particular the source size and evolution in different altitudes, as well as the velocity and energy of electron beams responsible for their generation. Methods. In this work types IIIb and U with stria structure radio bursts are analyzed using data from the LOFAR telescope including dynamic spectra and imaging observations, as well as data taken in the X-ray range (GOES and RHESSI satellites) and in the extreme ultraviolet (SDO satellite). Results. In this study we determined the source size limited by the actual shape of the contour at particular frequencies of type IIIb and U solar bursts in a relatively wide frequency band from 20 to 80 MHz. Two of the bursts seem to appear at roughly the same place in the studied active region and their source sizes are similar. It is different in the case of another burst, which seems to be related to another part of the magnetic field structure in this active region. The velocities of the electron beams responsible for the generation of the three bursts studied here were also found to be different

Poziom zrównoważonego rozwoju powiatów w Polsce

The aim of the study was to determine and evaluate the level of sustainable development of counties in Poland. Counties were divided into four types – voivodship cities, other cities, land counties in the immediate vicinity of voivodship cities and other land counties. Statistical data from the Local Data Bank of the Central Statistical Office of Poland for 2018 were applied. A set of indicators of sustainable development was defined. Using methods of multidimensional comparative analysis, synthetic indicators of economic, social and environmental development were determined. The measure of cohesion was used to assess the level of sustainable development of counties. It enabled dividing counties into five groups: a very low, low, medium, high and very high level of sustainability. The results show that only 20% of counties in 2018 was classified as a very high level of sustainable development class. Relatively, the highest level of sustainability was observed in land counties, both those bordering large cities and other ones. It was found that the environmental aspect may be a barrier in shaping the sustainable development of counties.Celem opracowania jest ocena poziomu rozwoju zrównoważonego powiatów w Polsce. Badaniami objęto powiaty oraz miasta na prawach powiatów. Powiaty podzielono na cztery typy – miasta wojewódzkie, pozostałe miasta, powiaty ziemskie w bezpośrednim sąsiedztwie miast wojewódzkich oraz pozostałe powiaty ziemskie. Do badań empirycznych wykorzystano dane pochodzące z banku Danych Lokalnych GUS za 2018 rok. Określono zestaw wskaźników zrównoważonego rozwoju. Za pomocą metody wielowymiarowej analizy porównawczej określono syntetyczne wskaźniki rozwoju społecznego, gospodarczego i środowiskowego. Następnie określono poziom zrównoważonego rozwoju i podzielono powiaty na pięć klas: o bardzo niskim, niskim, średnim, wysokim i bardzo wysokim poziomie zrównoważenia. Badania pokazały, że jedynie 20% powiatów charakteryzowało się w 2018 roku wysokim poziomem zrównoważonego rozwoju. Relatywnie najwyższy poziom zrównoważenia zaobserwowano w powiatach ziemskich, zarówno tych graniczących z dużymi miastami, jak i w pozostałych. Zrównoważenie w największym stopniu utrudniał aspekt środowiskowy

Hydraulic systems on maritime ships : operational and ecological safety

W artykule omówiono napędy hydrauliczne na statkach morskich według wybranych kryteriów. Zidentyfikowano zagrożenia eksploatacyjne oraz przedstawiono podstawowe zasady bezpiecznej eksploatacji systemów hydraulicznych na statkach.This article discusses hydraulic drives on marine vessels according to selected criteria. Operational hazards have been identified and basic principles for the safe operation of hydraulic systems on ships have been identified

The service life of the repair welded joint of Cr-Mo / Cr-Mo-Y

The service life of the repair welded joint of Cr-Mo / Cr-Mo-Y This paper presents the evaluation of the service life of dissimilar repair welded joint from Cr-Mo/Cr-Mo-V steel after 200,000 h service under creep condition. The investigations of microstructure using scanning electron microscopy, investigations of mechanical properties at room and elevated temperature as well as creep tests of the basic material from Cr-Mo and Cr-Mo-V steel and welded joint from these steels were carried out. The investigations allowed the tune of further safe operation of the repair welded joint in relation to the residual life of the materials to be determined. The evaluation of residual life and disposable residual life, and thus the estimation or determination of possible time of further safe operation, is crucial when the elements are operated much beyond the design work time