Physicochemical and Medical–Biological Properties of Carbon Sorbents Modified by Biologically Active Substances

Protection of Metals and Physical Chemistry of Surfaces - By means of chemical modification of the surface of a mesoporous carbon material (300–400 m2/g) biologically active substances...     

Structural and morphological transformations of carbon nanospheres during high-temperature,high-pressure processing

This paper presents analysis of structural changes in powders consisting of turbostratic carbon spheres with an average particle diameter of 250 and 25 nm after high-temperature, high-pressure processing at a pressure of 8 GPa. It has been shown that marked ordering of graphene sheets is observed at 1300°C and actively proceeds at higher temperatures. The major morphological species in the samples after processing is slabs of graphene sheets, and three-dimensional structural perfection is higher at the smaller particle size. Using high-resolution electron microscopy, samples of this powder were shown to contain diamond nanocrystallites.     

Elemental and phase composition,morphology, and chemical features of the surface of Al–Ni Alloys in contact with liquid Ga–In eutectic

A set of aluminum–nickel alloys has been studied. The elemental composition of the samples has been determined by atomic emission and atomic absorption spectrometry. X-ray diffraction analysis has revealed that the alloying of the metals leads to the formation of Al₃Ni and Al₃Ni₂ intermetallic compounds, while a portion of Al remains in a metallic phase. The local chemical composition and surface morphology of the original alloys and the alloys activated with the liquid Ga–In eutectic have been studied by scanning electron microscopy and X-ray microanalysis. It has been shown that the original alloys are characterized by a pronounced morphological heterogeneity of interfacial regions in the near-surface layers. It has been found that the studied Al–Ni alloys are activated by the liquid Ga–In eutectic; however, one of the alloy components—the Al₃Ni intermetallic compound—does not undergo significant morphological and chemical changes in contact with the liquid eutectic.     

Carbon support hydrogenation in Pd/C catalysts during reductive thermal treatment

The resistance of the Pd/C samples towards hydrogenation of the carbon support was studied in the temperature-programmed and isothermal regimes. Carbonaceous graphite-like material Sibunit was used as a carbon support. Pristine Sibunit was additionally graphitized via high temperature treatment (1900 °C) in an inert atmosphere. Both initial and graphitized supports were subjected to oxidative treatment in order to increase the amount of surface functional oxygen-containing groups. Palladium (1 wt%) was supported using an aqueous solution of H₂PdCl₄. All the samples were characterized by a low-temperature adsorption of nitrogen, transmission electron microscopy, and Raman spectroscopy. The graphitization procedure was found to decrease significantly the specific surface area of the support, while the oxidative treatment affects this parameter negligibly. Testing the Pd-containing samples in a hydrogen flow revealed the following order in accordance with amount of methane released: Pd/iSib » Pd/iSib-ox > Pd/gSib > Pd/gSib-ox.     

The Use of Mechanical Activation of Polyvinyl Chloride in the Presence of Alkalis for Synthesis of Porous Carbon Materials

Protection of Metals and Physical Chemistry of Surfaces - The synthesis of porous carbon materials was carried out by mechanochemical dehydrochlorination of polyvinyl chloride in the presence of...     

Catalytic Pd–Ag nanoparticles immobilized on fiber glass by surface self-propagating thermal synthesis

Pd–Ag nanoparticles with different Pd/Ag ratio were deposited onto fiber glass by using the technique of surface self-propagating thermal synthesis (SSTS) and characterized by X-ray photoelectron spectroscopy (XPS), atomic absorption spectroscopy (ААS), and EXAFS spectroscopy. The samples reduced in hydrogen exhibited the formation of Pd–Ag alloy whose tentative structure and composition were suggested. Thermally scheduled reduction of Pd–Ag catalysts in hydrogen made the Ag atoms partially oxidized. Reported are the catalytic properties of synthesized Pd–Ag samples in selective hydrogenation of acetylene.     

“Cold” synthesis of carbon from polyvinyl chloride with the use of an electron beam ejected into the atmosphere

This work shows the possibility in principle of forming hydrocarbon structures in polyvinyl chloride films free of admixtures and polyvinyl chloride films modified with 5-mass % ferrocene via a radiation chemical transformation in the atmosphere with the use of an electron accelerator with a plasma cathode operating in the pulsed-periodic mode maximal electron energy no higher than 160 keV, pulse length of 40 μs, and current density of 5 mA/cm². According to the results of semiquantitative X-ray microanalysis, an irradiated polyvinyl chloride film free of admixtures contains 92 of carbon, 6 of oxygen, and 2 mass % of chlorine; the irradiated polyvinyl chloride is an amorphous carbon material. A possible mechanism of the phenomenon is discussed.