Synthesis of highly porous zinc–carbon composites based on modified pine wood

Highly porous materials containing zinc oxide were prepared form modified pine wood. The growth dynamics of zinc oxide microcrystallites in the course of carbonization of pine sawdust mixed with ZnCl₂ was studied. The hexagonal wurtzite-type ZnO phase is formed at 400°С and is broken down at approximately 800°С. The synthesized composite material has a high specific surface area, up to 1900 m² g^–1. The relationships of the porous structure formation in the composite in relation to the temperature and subsequent treatment with water were revealed. Opening of the porous structure of the composite in the course of carbonization of modified pine sawdust is associated with the formation of crystal-like phases of carbon and ZnO.     

Synthesis of new 1-(3,4-dimethylphenyl)-1,5-dihydropyrazolo[3,4-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-4-one derivatives

New substituted pyrazolo[3,4-d]pyrimidin-4-ones have been synthesized as a result of a series of transformations including hydrolysis of ethyl 5-amino-1H-pyrazole-4-carboxylates, cyclization of the carboxylic acids thus obtained to pyrazolo[3,4-d][1,3]oxazin-4(1H)-ones, and treatment of the latter with substituted anilines. The final pyrazolo[3,4-d]pyrimidin-4-one derivatives can also be synthesized from 5-(arylamido)-1H-pyrazole-4-carboxylic acids in the presence of a catalytic amount of anhydrous zinc(II) chloride.     

Arguments in favour of physical reality of the peculiar (200÷300) Mpc scale in the distribution of the rich clusters of galaxies

Summary It is necessary to examine the significance of the recently discovered peak of spatial two-point correlation function determined for the rich Abel clusters. We discuss the different possibilities to do it and propose the programme of further observations.

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Riassunto è necessario esaminare il significato del picco recentemente scoperto della funzione di correlazione a due punti spaziale determinata per i cluster ricchi di Abell. Si discutono le diverse possibilità di farlo e si propone la programmazione di ulteriori osservazioni.

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Резюме Отмечается важность исследования недавно обнаруженного пика пространственной функции двух-точечной корреляции, определенной для больших Абеллевых кластеров. Мы обсуждаем различные возможности проведения исследований и предлагаем программу дальнейших наблюдений.

     

Adsorption of lead(II), cadmium(II) and dysprosium(III) from aqueous solutions using mesoporous silica modified with phosphonic acid groups

The mesoporous silica samples with different concentrations of phosphonic acid groups on the surface were obtained by direct template synthesis. The block-copolymer Pluronic P123 was used as a template, and sodium meta-silicate with diethylphosphatoethyltriethoxysilane as precursors. According to the SAXS diffractograms, mesoporous silica samples have a p6mm hexagonal symmetry. In addition, we used sol–gel method to synthesize xerogel with the same groups for comparison. All samples possess high values of specific surface area 615–730?m²/g and sorption pore volume. FTIR and potentiometric titration methods were used to investigate the surface layer of these samples. Sorption properties of the samples with phosphonic acid groups were studied in respect to a row of metal cations, among which we focused on lead(II), cadmium(II), and dysprosium(III) cations.

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