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The paper presents the results of contact strength and tribological property tests of spare parts made of a popular resin using a 3D DLP printing technology. Two printer models by the same manufacturer were used in the study. The post-processing technique, which shapes the final functional properties, was diversified. Surface performance properties were compared, i.e. Shore hardness, indentation hardness, Martens hardness, elastic modulus, and parameters related to surface creep and relaxation. Tribo-logical durability in rotary motion and tribological wear in reciprocating linear motion were also evaluated using micro- and nanotribometers. This was followed by surface analyses of the friction track of the analysed materials using microscopic methods: a scanning electron microscope, a WLI interferometric microscope, and an optical microscope. The results were statistically processed and the relationship between the parameters determined in the indentation test was determined. [ABSTRACT FROM AUTHOR]

The current paper is devoted to the synthesis of ceria-supported nickel-based catalysts starting from different precursors of the nickel active phase. Thermal decomposition of metal-containing precursors, deposited onto stable supports by dry impregnation, belongs to the industrially preferred, simple ways of catalyst preparation. The synthesized series of NiOx/CeO2 catalysts have been tested in dry methane reforming (DMR), in which two greenhouse gases, i.e., CO2 and CH4, are simultaneously converted into syngas. Both reaction progress and stability of the catalyst strongly depend on nickel speciation, which in turn can be determined by the nature of the chosen precursor. Contrary to relatively many studies focused on the importance of synthetic methods and conditions on nickel speciation, the effect of precursor nature on structural, textural, and functional properties of catalytic systems has neither been discussed much nor fully understood. The main goal of this paper was to elucidate the effect of precursors on the properties of NiOx/CeO2. Consequences of the use of various nickel precursors (simple inorganic salts, organometallic complexes, and chelates) have been analyzed in detail from the viewpoint of their beneficial influence on the catalytic performance of NiOx/CeO2 system (containing 3 wt. % of Ni) tested in DMR. [ABSTRACT FROM AUTHOR]

The valorization of greenhouse gases, especially when focused on carbon dioxide, currently belongs to the main challenges of pro-environmental chemical processes. One of the important technologies in this field is dry methane reforming (DMR), leading to the so-called synthesis gas (CO + H2). However, to be efficient and economically viable, an active and stable catalyst is required. Ni-based systems can be recommended in this regard. This research aimed to investigate how nickel content can influence the activity of model NiOx/CeO2 catalysts in DMR. A series of NiOx/CeO2 samples of various nickel loadings (0–10 wt.%) were prepared through dry impregnation. The obtained samples were characterized through XRD, RS, N2-BET, DRIFT, SEM, UV/Vis-DR, and XPS. Nonlinear changes in surface properties of the investigated samples with increasing nickel concentration were found. The observed changes are mirrored both in the determined nickel speciation and in the corresponding catalytic activity. The highest activity was found for the catalyst containing 3 wt.%. of nickel. [ABSTRACT FROM AUTHOR]

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The real/atomic structure of single phase homogeneous nanocrystalline Ce0.5Zr0.5O2±δ oxides prepared by a modified Pechini route and Ni-loaded catalysts of methane dry reforming on their bases was studied by a combination of neutron diffraction, synchrotron X-ray diffraction, total X-ray scattering and X-ray absorption spectroscopy. The effects of sintering temperature and pretreatment in H2 were elucidated. The structure of the mixed oxides corresponds to a tetragonal space group indicating a homogeneous distribution of Ce and Zr cations in the lattice. A pronounced disordering of the oxygen sublattice was revealed by neutron diffraction, supposedly due to incorporation of water into the structure when in contact with air promoted by the generation of anion vacancies in the lattice after reduction or calcination at high temperatures. However, such disordering has not resulted in any occupation of the oxygen interstitial positions in the bulk of the nanodomains.

Ce0.5Zr0.5O2 mixed oxides were prepared in a flow reactor in supercritical isopropanol with acetylacetone as a complexing agent. Variation of the nature of the Zr salt and the temperature of synthesis affected the phase composition, morphology and specific surface area of oxides. X-ray diffraction and Raman spectroscopy studies revealed formation of metastable t” and t’ phases. Oxides are comprised of agglomerates with sizes depending on the synthesis parameters. Loading NiO decreases the specific surface area without affecting X-ray particle sizes of supports. Such sintering was the most pronounced for a support with the highest specific surface area, which resulted in the lowest surface content of Ni as estimated by X-ray photoelectron spectroscopy and in the formation of flattened NiO particles partially embedded into the support. The catalytic activity and stability of these samples in the dry reforming of methane were determined by the surface concentration of Ni and the morphology of its particle controlled by the metal-support interaction, which also depends on the type of catalyst pretreatment. Samples based on ceria-zirconia oxides prepared under these conditions provide a higher specific catalytic activity as compared with the traditional Pechini route, which makes them promising for the practical application.

Mixed nanocrystalline Ce-Zr-O oxides (Ce/Zr = 1 or 7/3) were prepared by modified Pechini route using ethylene glycol solutions of metal salts. Detailed characterization of their real structure and surface properties by X-ray diffraction on synchrotron radiation with the full-profile Rietveld analysis, high resolution electron microscopy with elemental analysis, Raman spectroscopy, UV-Vis and X-ray photoelectron spectroscopy revealed a high homogeneity of cations distribution in nanodomains resulting in stabilization of disordered cubic phase. This provides a high dispersion of NiO loaded on these mixed oxides by wet impregnation, a high reactivity and mobility of oxygen in these catalysts and strong interaction of Ni with support in the reduced state. This helps to achieve a high activity and coking stability of developed catalysts in CH4 dry reforming in feeds with CH4 concentration up to 15% and CH4/CO2 ratio =1.

Positive environmental and technological contexts make dry methane reforming (DMR) an extensively studied reaction. During this process two main greenhouse gases CH4 and CO2 can be simultaneously converted into syngas – a mixture of CO and H2. Supported-nickel is one of the most frequently applied DMR catalysts. Their activity depends mainly on Ni concentration, kind of its precursor and a deposition method. As DMR is a demanding high-temperature reaction, it requires not only an active but first a very stable catalyst. Structural, textural and functional properties of such support remain thus of crucial efficiency. Main aim of this work was to elucidate how the synthesis of CeO2-ZrO2 support obtained by supercritical fluid method (i.e. at temperature of 400°C under a pressure of 25 MPa), can influence the properties of Ni-based DMR catalysts. The supports of various compositions (CeO2 content from 100 to 0 %), subsequently calcined at 800°C for 6h in air have been analyzed. Nickel was deposited from nitrate(V) precursor via classical wet impregnation. The final catalysts have been characterized structurally (XRD, RS), texturally (BET, SEM) and functionally (UV/Vis-DR, XPS). Catalytic tests in dry methane reforming reaction have been performed to determine activity and stability of the synthesized samples.

Tekst porusza problematykę zmian w polityce karania na terenie Zjednoczonego Królestwa w Anglii i Walii jakie dokonały się w latach 1970-2005. Podstawę rozważań przedstawionych w artykule stanowi zwrot jaki dokonał się w brytyjskiej polityce karnej w latach dziewięćdziesiątych. Omawiany przez autora tekstu model brytyjskiej polityki karnej charakteryzował się wówczas wydłużeniem izolacji więziennej sprawców powrotnych i niebezpiecznych skutkując wzrostem populacji więziennej przy jednoczesnym spadku nasilania się przestępczości. A. Adamski prowadzi odbiorcę przez poszczególne etapy zmian i ewolucji polityki karnej w Zjednoczonym Królestwie w wybranych latach. W celu ilustracji swoich rozważań autor artykułu przedstawia wykresy ukazujące populację więzienną w Anglii i Walii w latach 1975–2005. W tekście przedstawione zostały poszczególne etapy stanowiące odzwierciedlenia zmian m. in tzw. „strategię martwego punktu” w latach 1975-1979, dwutorową politykę karną konserwatystów w latach 1979–1992 oraz wzrost represyjności brytyjskiego systemu karnego po 1993 roku. Opracowanie zawiera również charakterystykę współczesnego systemu karania w Anglii i Walii oraz strukturę orzekanych kar w systemie brytyjskim. W przedstawionych wnioskach autor tekstu stara się porównać politykę karną w Anglii i Walii z innymi krajami Europy Zachodniej. A. Adamski podkreśla, że brytyjski system sprawiedliwości cechuje się surowym traktowaniem sprawców przestępstw i skazywaniem ich na karę pozbawienia wolności. Wśród źródeł narastających tendencji rygorystycznych w krajach brytyjskich autor wskazuje na rozwój społecznego neoliberalizmu co podnoszone jest także przez innych badawczy zjawiska. Według niego na kształt polityki karnej i poziom represyjności największy wpływ ma istniejący w danym momencie klimat polityczny.