Asphaltene thin films obtained from coal-tar pitch

Abstract

Preparation and characterization of highly pure silica from sedge as agricultural waste and its utilization in the synthesis of mesoporous silica MCM-41

This study presents the characterisation and evaluation of the catalytic potential of an alloy with a composition referring to the quasicrystal from the Al-Cu-Co system. The material was synthesised through a melt-spinning process, providing rapid solidification conditions and a favourable material form of thin ribbons. Microstructural and chemical analyses were performed using scanning electron microscopy, X-ray diffraction and transmission electron microscopy methods. The obtained results confirmed the presence of a major phase which was a decagonal quasicrystal in the form of globular grains and additional crystalline phases occurring along the grain boundaries. The catalytic potential of the materials was explored using phenylacetylene hydrogenation. The catalyst, obtained by pulverising the ribbons, demonstrated catalytic activity with over 40% phenylacetylene conversion and selectivity exceeding 60% for styrene production under mild reaction conditions. The recovered catalyst displayed a stable phase composition, as confirmed by X-ray diffraction, and unchanged morphology, indicating the possibility of catalyst reuse for subsequent reaction cycles. The presented results provide insight into the experimental verification of the catalytic properties of the developed environmentally friendly catalysts.

Morphology control of titanium oxides by tetramethylammonium cations in hydrothermal conditions

Methods of transmission and scanning electron microscopy and chemical microanalysis, electron diffraction, and X-ray diffraction were used to systematically study the structure and the chemical and phase composition of the Ni50Ti38Hf12 alloy synthesized by rapid quenching from the melt and subjected to various heat treatments. The critical temperatures of the devitrification of the initially amorphous rapidly quenched alloy and the B2 ↔ B19′ thermoelastic martensitic transformations have been determined. The lattice parameters of the B2 austenite and thermoelastic B19′ martensite have been measured. The main features of the formation of an ultrafine-grained structure in the alloy and the subsequent phase transformations (martensitic transformation and the decomposition with the formation of an intermetallic phase of the (Ti,Hf)2Ni type) have been studied depending on the regimes of heat treatment. Based on the results of measurements of mechanical properties upon tension (σM, σu, and δ) and the shape-memory effects (degree of shape recovery depending on the deformation by bending; and magnitude of the reversible strain erev), regimes for obtaining high-strength and plastic states of the alloy with a shape-memory effect have been established.

A functional membrane, composed of the nanoparticles of methylene blue (MB) and Nafion, was constructed during the present study. The materials were characterized by the methods of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-Visible and FT-IR. The average diameter of new nano-particles was estimated to be about 60 nm. A novel Nafion-riboflavin membrane was also constructed and characterized by the methods of SEM, TEM and UV-Visible spectroscopy. The estimated average diameter of the new nanoparticles was about 60 nm. The functional membranes of Nafion-riboflavin and Nafion-methylene blue showed a quasi-reversible electrochemical behavior, on the gold electrode, with a formal potential of -562 \pm 5 and -305 \pm 5 mV (vs. Ag/AgCl), respectively. Some electrochemical parameters were also estimated, indicating that the systems present good and stable electron transfer properties. Our data proved that Nafion can be an interesting and helpful material in constructing Nanoparticles of different electro-active materials and in their stable immobilization.

Influence of the nanostructure of Ti-TiN-(Ti,Al,Cr)N multilayer composite coating on tribological properties and cutting tool life

Data have shown that on the internal surface of reused haemodialysis membranes complement elements of plasma proteins, cells and cellular debris from the patient's blood are deposited. The aim of our study was to identify the effect of reuse on the haemodialysis membrane surface. Original and reused haemodialysis membranes were studied by the methods of light, transmission and scanning electron microscopy, immuno-histochemistry and X-ray spectrum element analysis. With reuse the membrane surface becomes uneven, and its continuity may break. Plasma protein and cellular elements are deposited on the damaged surface following continued reuse. Presence of IgM deposists were confirmed by immunohistochemical observation. Moreover, following reuse the X-ray spectrum analysis verified structural changes in the haemodialysis tube compared to the control material; accumulated aluminium, silicon, phosphorus, sulphur and chlorine were detected on the wall of the dialysis membrane.

Catalytic properties of Mg 3(VO 4) 2–MgO system in oxidative dehydrogenation of ethylbenzene

Composite films of polybutylene adipate terephthalate (PBAT) were prepared by adding thermoplastic starch (TPS) (TPS/PBAT) and nano-zinc oxide (nano-ZnO) (TPS/PBAT/nano-ZnO). The changes of surface morphology, thermal properties, crystal types and functional groups of starch during plasticization were analyzed by scanning electron microscopy, synchronous thermal analysis, X-ray diffraction, infrared spectrometry, mechanical property tests, and contact Angle and transmittance tests. The relationship between the addition of TPS and the tensile strength, transmittance, contact angle, water absorption, and water vapor barrier of the composite film, and the influence of nano-ZnO on the mechanical properties and contact angle of the 10% TPS/PBAT composite film. Experimental results show that, after plasticizing, the crystalline form of starch changed from A-type to V-type, the functional group changed and the lipophilicity increased; the increase of TPS content, the light transmittance and mechanical properties of the composite membrane decreased, while the water vapor transmittance and water absorption increased. The mechanical properties of the composite can be significantly improved by adding nano-ZnO at a lower concentration (optimum content is 1 wt%).

The article considers laser alloying technologies of surface layers of samples made of structural steel using powder filler add-on materials based on tungsten carbide and chromium. Structural transformations, concentration changes of chemical elements, grain and subgrain structures, dislocation density, size and volume fraction of phase precipitates, causes of crack formation in treated surface layers under various alloying regimes have been studied by the methods of optical, analytical scanning, and transmission electron microscopy. It was found that the tendency to crack formation of samples after laser alloying is due to structural (crystallite size, shape factor) and concentration changes associated with redistribution of elements, in particular, chromium. Noticeable changes in the structural-phase state of the treated surfaces are observed for an optimal mode of laser alloying. This laser alloying regime is characterized by a uniform distribution of dislocations with a general decrease in their density. The sizes of phase precipitates in the surface layers are more dispersed and evenly distributed in the internal volumes of grains. These are nanoparticles with a size of 40...100 nm and larger phase precipitates (up to 1 μm).

In this thesis, geometry is used as a basis for conducting experiments aimed at growing and arranging inorganic minerals on curved interfaces. Mineralisation is directed using crystalline and liquid-crystalline metallic soaps and surfactant/water systems as templates.¶ A review of the history, syntheses, structure and liquid crystallinity of metallic soaps and other amphiphiles is presented as a foundation to understanding the interfacial architectures in mesostructured template systems in general. ...

Comparative Study of the Modification of Coal Tar Pitch for Higher Carbonization Yield and Better Properties

Preparation, properties and anticancer effects of mixed As4S4/ZnS nanoparticles capped by Poloxamer 407

Severe plastic deformation influence on the structure transformation of the amorphous Zr62.5Сu22.5Al10Fe5 alloy