V. I. Roldugin

Thermogravimetric analysis of the aluminum-polypropylene mixtures after plastic deformation under high pressure

The thermogravimetric analysis of the aluminum-polypropylene mixture of varied composition was performed to determine the effect of plastic deformation under the high pressure. It was found that a loss of mass by the mixed samples up to 400°C is due to decomposition of a polymer and the mass gain above 500°C, due to aluminum oxidation.

Effect of the preparation method of silver and gold nanoparticles on the photosensitizing properties of tetraphenylporphyrin–amphiphilic polymer—nanoparticle systems

The ranges of concentrations of silver and gold nanoparticles in which the rate constants of the test for the photodynamic therapy (PDT) reaction of oxidation of tryptophan in an aqueous medium in the presence of photosensitizer remain virtually the same (without nanoparticles) are found. This testifies to the feasibility of causing additional photothermal damage on tumor cells by transforming the absorbed energy of electromagnetic radiation in the area of the plasmon resonances of the administered nanoparticles into heat energy in the PDT of tumors. Metal nanoparticles are obtained by photochemical and chemical methods, and by laser ablation. Tetraphenylporphyrin solubilized with Pluronic F127 (to attain its solubility in aqueous systems), the optical absorption band of which is close to the plasmon absorption bands of nanoparticles, is used as a photosensitizer.

Formation of aqueous colloidal solutions of selenium and silicon by laser ablation

161 Aqueous colloidal dispersions of selenium and sili con particles were obtained by laser ablation. It was shown that, in the case of selenium, a multimodal ensemble of particles forms, whereas in the case of sil icon, a unimodal one emerges. Selenium nanoparti cles are amorphous, and large (200–300 nm) particles of selenium and silicon are clearly faceted and can be considered crystalline. For the first time, by laser abla tion, submicron faceted crystalline particles of sele nium and silicon were produced. The possible mecha nisms of the formation of particles were discussed. The obtained dispersions were demonstrated to be promis ing as sources of micronutrients for agricultural pro duction.

A study of the mixtures of polystyrene and polyvinyl fluoride with aluminum after plastic deformation under high pressure using DSC and thermogravimetry

Mixtures of powdered polystyrene and polyvinyl fluoride with aluminum exposed to plastic deformation under pressure of 1 and 4 GPa, have been studied by DSC and thermogravimetry. It has been established that, in the deformed mixtures at temperatures up to 200°C, exothermal processes take place. Interaction between polymer decomposition products and aluminum has been studied, as have its oxidation and nitrogenation.

Formation of gold nanoparticles in aqueous solutions of cellulose derivatives and a study of the properties of these nanoparticles

It was demonstrated that gold nanoparticles can be obtained by using cellulose ethers, methyl hydroxyethyl cellulose and carboxymethylcellulose as reducing agents and also as nanoparticle stabilizers. IR spectral studies revealed a difference between the mechanisms of reduction and nanoparticle stabilization by these cellulose derivatives. A scanning tunnel microscope was used to examine composite films formed from nanoparticle dispersions on the surface of polycrystalline gold films. It was demonstrated that, in the case of gold nanoparticles, densely packed globular structures are formed in a carboxymethyl cellulose solution. A fibril-like structure of layers is formed in the Au+(methyl hydroxyethyl cellulose) system.

Thermally induced processes in mixtures of aluminum with organic acids after plastic deformations under high pressure

DSC is used to measure the thermal effects of processes in mixtures of solid organic dibasic acids with powdered aluminum, subjected to plastic deformation under pressures in the range of 0.5–4.0 GPa using an anvil-type high-pressure setup. Analysis of thermograms obtained for the samples after plastic deformation suggests a correlation between the exothermal peaks observed around the temperatures of degradation of the acids and the thermally induced chemical reactions between products of acid degradation and freshly formed surfaces of aluminum particles. The release of heat in the mixtures begins at 30–40°C. The thermal effects in the mixtures of different acids change according to the order of acid reactivity in solutions. The extreme baric dependences of enthalpies of thermal effects are associated with the rearrangement of the electron subsystem of aluminum upon plastic deformation at high pressures.

Electrochemical synthesis of iron and platinum nanoparticles in deionized water

The processes of formation of disperse phase in water in a two-electrode electrochemical cell with platinum or steel electrodes in the constant electric potential application regime are studied. It is established by the method of dynamic light scattering (DLS) that the charge transfer process in the system is accompanied by formation of nanoparticles (NPs) made of electrode material in the aqueous medium. It is shown that the dynamics of changes in the electric current conforms to the dynamics of NP formation. Simultaneous registration of absorbance spectra of the aqueous medium at various moments of time has shown the presence of plasmon resonance bands corresponding to a platinum NP. In case of platinum electrode, a residue of platinum-containing NPs was found on the cathode using energy-dispersive X-ray microanalysis (EDXMA) and electronic spectroscopy for chemical analysis (ESCA) methods. The possibility of cathophoresis of platinum NPs forming on the anode to the cathode under effect of the applied voltage in the cell with water.

Exothermic Processes in aluminum-polypropylene mixtures after high-pressure plastic deformation

The influence of high-pressure plastic deformation on aluminum-polypropylene mixtures of different compositions was examined by thermal analysis techniques. The thermokinetic characteristics of the process were determined, and assumptions concerning the mechanism of the interaction of the components were made.