Home – Home – Jornals – Chemistry for Sustainable Development 2016 number 5

Magnetic resonance imaging (MRI) is one of the most powerful non-invasive methods of research of organs and tissues that is widely used in modern clinical medicine. To achieve a better visualization of the pathological focus contrast/imaging contrast agents are applied, and in case of ¹H MRI - substances that increase the relaxation rate of water protons in the surrounding tissues and thus increase the image contrast. The review considers various ways to improve the properties of current contrast/imaging contrast agents: from covalent/noncovalent binding of chelate complexes of paramagnetic metal ions with human serum albumin (HSA) up to the development of HSA-based multifunctional nanostructures for the study of pathological processes by an MRI method both on ¹H nuclei and ¹⁹F nuclei. The focus is on the evaluation and systematization of known results in the development of imaging systems for the detection of malignant tumours. Analysis of the publications devoted to problems of creation of affine chelate complexes of paramagnetic metal ions with a high affinity to a specific site on albumin indicates an active and growing interest to the area of chemistry. The accumulation of knowledge about molecular structure of albumin and its complexes with medicinal preparations and endogenous ligands in combination with the development of bioinformatics creates preconditions for the development of affine contrast/imaging contrast agents with optimum parameters of highly selective binding to proteins. On the basis of the critical analysis, generalized conclusions were made about the key parameters of imaging systems based on albumin that determine the study informativeness of the affected area by ¹H/¹⁹F MRI methods. Due to binding contrast/imaging contrast agents with albumin, the relaxation ability of the preparation is enhanced; its circulation time in the blood and the efficiency of accumulation in the tumour is increased. This contributes to the contrast increase in an MR image between healthy and pathological tissue, improves the diagnosis accuracy and, as a consequence, the therapy effectiveness.

A synthesis technique of microgranules and microcapsules from bioactive hydroxyapatite was developed. Their structural and phase composition was investigated, electron microscopic analysis of the bioresorbable material was carried out. Biological and preclinical trials showed that when filling the bone defect with hydroxyapatite microgranules in animals a full-fledged bone tissue was formed.

The electrosynthesis process of carboxylic acids (butyric, caproic, pelargonic, and capric) by indirect electrocatalytic oxidation of aliphatic alcohols (1-buthanol, 1-hexanol, 1-nonanol and 1-decanol) with the participation of reactive oxygen species (ROS). The process was performed using three schemes of ROS generation: 1) oxidation at the anode (anodic); 2) oxidation at the anode with the addition of H₂O₂ to the electrolyte (anode + H₂O₂); 3) paired electrolysis - oxidation at the anode with concurrent generation of carbon-graphite cathode while passing oxygen through the electrolyte solution. It was found that when using as the anode oxyhydroxide nickel electrode the most effective scheme of oxidation of aliphatic alcohols was the paired electrosynthesis: at the pushed quantity of electricity Q / Q _theor = 0.14, the yield of acids by current amounted to 168 % for oil and 148 % for caproic acid; Q / Q _theor = 1.0 output capric acid was 64 %. On boron-doped diamond electrode, further generation of reactive oxygen species leads to a decrease of the yield of the target product due to its further oxidation, therefore, indirect anodic oxidation is optimal to apply: when Q / Q _theor = 1.0, the yield by current of pelargonic acid is equal to 89 %. It was concluded that for complex optimization of the electrolysis process, the electrosynthesis method of carboxylic acids by indirect electrocatalytic oxidation of aliphatic alcohols could be considered as an alternative to the existing.

Linear nickel nanostructures with a different ratio of their length to diameter were synthesized by reduction of nickel formate with hydrazine hydrate in the ethylene glycol medium. The effect of temperature, reduction time, concentration of nickel formate on the products of its reduction was studied. The morphology and properties of the resulting nickel nanoparticles were studied by X-ray phase analysis, scanning and transmission electron microscopy. It was shown that reduction of nickel formate in ethylene glycol with hydrazine hydrate proceeded without additional alkalizing the medium, which prevents the formation of nickel hydroxide and contamination of the final product. It was established that at a temperature of 130 °C, well-crystallised metal nickel in as nanowires with a diameter of approximately 100 nm and length of 2-4 µm was formed in the system. Increasing the reaction temperature to 150 °C is accompanied by an increase of the rate of nickel reduction, decrease of the size of the generated particles up to 50 nm and morphology change of the particles. It was discovered that increasing the concentration of nickel formate in the feed solution virtually did not affect the size of the resulting particles, however, led to their aggregation increase. As a result, aggregated particles of almost spherical shape with a fairly narrow size distribution were obtained. With an increase the of the synthesis duration the length of the nanowires increases significantly, in contrast to their diameter. At the synthesis duration of 1 h, the particles have the form of nanowires with a length of 5-10 mm and are composed of nanoparticles with a size from 50 to 100 nm.

The rheological properties of coal-water suspensions prepared by the mechanoactivation method of coal in the dispersion medium with the addition to the main reagent (sulphurised naphthalene formaldehyde) of anionic and nonionic surfactants. It was found that the joint use of surfactants allowed increasing the concentration of coal in suspensions due to a more efficient liquefaction process. Coal-water suspensions obtained using nonionic (oxyethylated octylphenols) and anion-active surfactants (sodium dodecyl sulphate and sodium dodecylbenzenesulfonate) are characterized by the optimum rheological properties.

The morphology of mixtures based on polyhydroxybutyrate (PHB) and ethylene-propylene copolymer (EPDM) was studied. Polymer blending was carried out by hot pressing. Flat films obtained by the method of direct hot pressing served as the study objects. Analysis of mixtures was performed using a set of structure-sensitive methods: physicomechanical, scanning electron microscopy and DSC. The resulting dependencies have three concentration areas that characterize the phase structure of mixtures. The first region (0-40 % of PHB) corresponds to the system of the continuous EPDM matrix and dispersed PHB phase. The second area (50-70 % of PHB) is characterized by a structure of two continuous phases (EPDM and PHB) and the largest interphase boundary. The third area consists of the continuous PHB phase and dispersed EPDM phase. Average particle sizes of the dispersed phase were determined. It was shown that EPDM and PHB were characterized by a low reactivity towards oxygen. It was determined that the formation of the interfacial layer led to an increase of the reactivity of the mixtures towards oxygen, particularly in the area of phase inversion.

Preparation techniques of multifunctional additives from textile industry wastes were developed. The possibility of their use in the production of synthetic rubbers was considered. Promising technological methods of modification of emulsion rubbers with powdered cellulose additives through their input at various stages of the production of elastomeric compositions were proposed. It was established that it was expedient to introduce multifunctional additives in the form of dispersions with a solution of the coagulating agent. Peculiarities of the effect of multifunctional additives on elastomeric compositions were revealed. It is shown that the application of multifunctional additives for the modification of styrene-butadiene rubber allowed reducing the consumption of the coagulant and acidifying agent, lowering an ecological load on the environment, as well as reducing the duration of drying rubbers due to a dominant acceleration of its final stage.

The content of reserve and biologically active substances in vegetative organs of Muscari armeniacum was studied. The presence of sugar, starch, saponins, ascorbic acid, pectins, protopectins and catechins in the bulbs of M. armeniacum during the vegetation period (2007, 2009-2011) under the conditions of forest-steppe zone of West Siberia was established. Flavonols were detected in leaves, the contents of which in all years of observation amounted to 1.8-2.2 %. It was determined that by the pre-winter, the amount of sugar in the bulbs is reduced by 2-4 times compared to the spring, and starch was increased in 1.5-2 times. In May, the content in above-ground organs of ascorbic acid is higher by 5-10 times, sugar - by 1.5 times, catechins - in 2 times in comparison with underground bodies. It is noted that the bulbs contain in 2-3 times more, and leaves do in 5-6 times more protopectins in comparison with pectins. The content of biologically active and reserve substances of vegetative organs of M. armeniacum depends only on the individual and seasonal development of the species.

The elemental composition of the roots of Siberian sea-buckthorn ( Hippophae rhamnoides L. ssp. mongolica Rousi) grown under the endemic conditions of West Siberia was studied in detail by synchrotron radiation X-ray fluorescence (SR-XRF) analysis. The joint quantitative content of K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Pb in roots and soil was determined, as well as biological adsorption coefficients of these elements from soil. Peculiarities of adsorption of elements, specific for this biological genus, were determined. In comparison with aboveground organs (leaves, bark and fruits), Siberian sea buckthorn roots are characterized by the maximum adsorption of vitally necessary chromium, iron, molybdenum and selenium. Additionally, extremely high adsorptions of elements with unidentified biological role were detected: niobium, zirconium, titan and yttrium. The effect of over-concentration with roots was determined for niobium and molybdenum. Due to a high accumulation level of chromium, Siberian sea-buckthorn roots can serve as perspective sources of biogenic flora of this vitally necessary element for preventive care purposes to fight so called civilization diseases - diabetes and atherosclerosis. It was shown that Siberian sea buckthorn roots in the amount of 1.5-2.0 g ensure the daily need of the organism in chromium. It was concluded that sea buckthorn was not a concentrator of lead recognized as a toxic element, since its uptake by roots is comparable to the average index for plants in the earth's land surface.

The chloride ion is harmful impurity in zinc sulphate electrolyte. The possibility of extraction purification of zinc solutions from the chloride ion using trialkylphosphine oxide (TRPO, Cyanex 923) as an extractant in petroleum paraffins. It was shown that the extraction degree of the chloride in the form of HCl is low - no more than 14.3 %. The chloride ion is extracted as zinc chloride in the composition of the extractable compound of the composition [ZnCl₂ x 2TRPO] with a high purification degree of zinc solutions (≥90 %). Analysis of extraction equations of zinc chloride showed that extraction of the chloride ion in a great extent depends on its starting concentration in the water phase; moreover, distribution indexes of the chloride are reduced with decreasing the concentration. It was also shown that with increasing the concentration of zinc in the starting water solution and extractant, distribution coefficients of the chloride ion are increased. Judging by the extraction isotherm of the chloride with 50 % of TRPO, three extraction stages at O/W = 1 : 1 are necessary to achieve the residual content of the chloride in the raffinate from 5 to 0.1 g/L. Reextraction of zinc chloride from the organic phase is hampered. The attempts to reextract the chloride with water, solutions of phosphoric acid and Trilon B proved to be ineffective. Virtually complete reextraction zinc chloride (ε_Cl = 99.2 %) is achieved when processing the organic phase that represent a mixture of TRPO with tributyl phosphate, 5 % aqueous ammonia solutions. Taking into account good results on purifying zinc electrolytes from the chloride ion obtained with TRPO further studies should be directed at a broader search for reextractants and new extraction systems based on TRPO that ensure not only efficient extraction of the chloride ion from solutions but also its reextraction.

Samples of hydroxyapatite (HAP) were synthesized by the mechanochemical method with introducing into the reaction mixture from 0.1 to 1.5 mol of Al₂O₃ per 1 mol of HAP. The samples after mechanochemical synthesis and annealing were studied by X-ray phase (XPA) methods with the clarification of elementary cell parameters, crystallites size and calculation of phase concentration according to the Rietveld method, as well as by IR spectroscopy method and electron microscopy with energy-dispersive X-ray microanalysis. It was found that after mechanochemical synthesis, according to XPA data, single-phase nanocrystalline HAP without original and accompanying phases was formed. The cell parameters of mechanochemically synthesized HAP slightly change after the introduction of 0.1 mol of aluminum oxide, and then remain constant. After annealing of the samples, entering into the HAP structure to 0.5 mol of aluminium ions per 1.0 mol of HAP was found. Single-phase Al-substituted HAP was obtained when introducing into the reaction mixture up to 0.25 mol of aluminum oxide. When introducing 0.5 mol and more of HAP alongside with Al-substituted HAP, calcium aluminates of the composition of Ca₃Al₂O₆ and Ca₁₂Al₁₄O₃₃ are formed. It is not clear yet, in which form aluminum enters the HAP structure. The issue of the coordination environment of aluminate that enters the structure of Al-substituted HAP was considered. The octahedral environment of aluminum ions is characteristic for calcium aluminates; however, when substituting phosphate with other anions the cation of the complex anion usually has the tetrahedral environment. Based on data obtained by the IR spectroscopy method, it was suggested that with introducing aluminum oxide in the amount of 1.0 and 1.5 mol the appearance of absorption bands in the region of 745-900 cm^-1 in IR spectra of the samples was conditioned by entering aluminate in the apatite structure as a group in the tetrahedral environment, as in Ca(AlO). Aluminium-substituted HAP can be of interest for coating medicinal corundum ceramic implants.

The consistent pattern of distribution and transformation of petroleum hydrocarbons after displacement from the reservoir model was studied by the integrated method using oil-displacing the composition containing carbamide and natural sources of the enzyme urease (amidohydrolase EC 3.5.1.5). Depending on the time and concentration the catalytic activity of natural sources of urease in the processes of carbamide hydrolysis was determined. The optimum enzyme/substrate ratios and time of carrying out hydrolysis to achieve the maximum alkaline reaction with pH 9.0-10 were selected. Chromatographic analysis of gaseous products of carbamide hydrolysis at a temperature of 25-30 °C showed that under identical experiment conditions, urease of the beet mass represents a higher enzymatic activity in comparison with soybean flour. The effect of gaseous products of carbamide hydrolysis on rheological properties of viscous tarry oil of the Usinsk deposit and viscous paraffin oil of the Tamsagbulag deposit (Mongolia) was studied. It was found that the composition of gaseous hydrolysis products did not affect rheological properties of oils. On the example of viscous oil of the Usinsk deposit, model displacement was carried out by the integrated method at a temperature of 25 °C using urease of beet mass and soybean flour. The additional volume of oil in the control variant with application of a solution of oil-displacing composition amounted to (16±1.2), soy - (20.3±1.8), and beet mass - (24.9±2.2) mass %. Additional oil displacement in the control variant is carried out due to the detergent properties of the composition containing a surfactant, in experimental - due to the detergent properties of the composition and gaseous products of enzymatic hydrolysis of carbamide that form inside of the reservoir an oil-displacing system. Chromato-mass spectrometry analysis of original oil and displaced by the developed method confirmed the identity of the composition of hydrocarbons, including n-alkanes, hetero-organic and aromatic structures, among them steranes and hopanes.

New solid solutions of bismuth titanates with the pyrochlore-type structure Bi_{2 - y} In _x Ti₂O_{7 - δ} ( y = 0.4 at x = 0.2-0.6; y = 0.6 at x = 0.4-0.6) and Bi_{2 - y} Mg _x Ti₂O_{7 - δ} ( y = 0.4 at x = 0.05-0.3; y = 0.6 at x = 0.1-0.6) were obtained using solid-phase synthesis and the method of burning nitrate-organic precursors. The formation of single-phase compounds with the pyrochlore-type structure was confirmed by XPA method. According to results of qualitative elemental analysis and local microanalysis, the chemical composition of the samples remains unchanged after high temperature annealing. Based on comparison of the pycnometric and X-ray densities of compounds, the distribution variant of dopant atoms (In, Mg) according to X-ray positions of the pyrochlore structure was proposed. It was shown that indium and magnesium atoms populated initially vacant A (Bi)-positions of the pyrochlore structure. With increasing the dopant content a part of In and Mg atoms occupy Vi (Ti)-position. The results of the full-profile treatment of diffractogram of the compound Bi_1.6In_0.4Ti₂O₇ performed with various options of the dopant (In) distribution, coincide with the results of the comparison micrometrical density and the densities calculated for a certain cation distribution - hitting all of the indium atoms in vacant A (Bi) positions. It was determined that the presence of bismuth and vacancies in the oxygen sub-lattice O^¢ of the pyrochlore structure led to the appearance of the proton conductivity in a wet atmosphere in a temperature range of 240-640 °C. Compounds Bi_1.6In_0.2Ti₂O_6.7 and Bi_1.4Mg_0.1Ti₂O_6.2 are characterized by the value of proton conductivity equal to 2.2 10^-6 S/cm at a temperature of 400 °C and frequency of the supplied field of 1 kHz, which is by 1.5-2 orders of magnitude higher when measuring this parameter under the conditions of the dry air atmosphere.

Some parameters of the molecular properties of new benzo[d]thiazole and 1,3,4-thiadiazole derivatives, present at the planning phase of chemical synthesis, were studied. Using the web resources chemicalize.org and molinspiration.com a number of indicators were determined: number of possible stereoisomers and tautomers, molecular refraction, distribution coefficient in the system octanol-water (log P ), polar surface area, number of rotatable bonds, molecular volume, according to the “rule of five” by Lipinski, Ghose, Veber and Muegge filters, lead likeness, and bioavailability. It was found that all the studied compounds satisfy the “rule of five” Lipinski on the following parameters: molecular weight, number of hydrogen bond acceptors, and number of hydrogen bond donors. It was determined that only compound 12 containing electron-releasing groups (CH₃) in the 5th and 6th positions of the benzo[d]thiazole fragment had log P = 5.08 and did not satisfy the “rule of five” by Lipinski on the distribution coefficient in the system octanol -water (log P < 5). However, if instead of log P one uses the indicator miLog P , the compound 12 also satisfies this rule (miLog P = 4.49). It was established that the number of possible tautomers substances varied: most of the derivatives have three tautomeric forms, while compounds 9 and 16, theoretically can have six tautomers. It was determined that the area of the polar surface of benzo[d]thiazole derivatives varied in the limits of 79.29-92.18, and 1,3,4-thiadiazole derivatives - 92.18-101.41. It was found that the number of rotatable bonds of the compounds under investigation varied from 4 to 6. The data obtained about the molecular properties of the compounds are of value at the targeted synthesis.

Thin films of the composition TiO₂, TiO₂-SiO₂, TiO₂-SiO₂-NiO were obtained by the method of sol-gel synthesis from film-forming solutions, resistant to destruction. The optimum conditions for the preparation of titanium, silicon and nickel oxides from film-forming solutions were determined. It was found that at the simultaneous introduction of tetrabuthoxytitanium, tetraethoxysilane and/or of nickel chloride, the rheological stability of film-forming solutions was reduced. It was determined by ellipsometry methods that the thickness of porous TiO₂ films with a refractive index of 2.307 was equal to 12 nm. The introduction of silicon and/or nickel oxides in the films composition contributes to the reduction of the refractive index by 2-11 %. It was found according to the BET method that the layers of the composition 75TiO₂-20SiO₂-5NiO (mol. %) on the surface of the fibreglass carrier were porous, the average pore size is equal to 3.3 nm. The total area of the specific surface area of the material increases from 0.3 to 2.5 m²/g. The resulting material shows activity in deep and partial oxidation of n -heptane. In a temperature range of 210-350 °C, the main products are ketones. At a temperature above 350 °C, a depth of oxidation increases, simultaneously, the yield of α-olefins is observed.

Dispersed particles of the iron subgroup (Fe, Co, Ni) possess by a number of specific physical and chemical properties (functions), capable of interacting with the environment under conditions, remote from equilibrium. Particles in such an active condition are called polyfunctional nanodimensional systems (PNS) [1]. In cases, when conditions for a multi-stage technology arise, PNS automatically selects the thermodynamically preferable sequence of technology stages and acts as a physicochemical nanorobot (PCNR) that governs the nanotechnology. In the present article, as a demonstration model, nickel nanoparticle is taken as the role of PCNR that governs the nanotechnology of the production of various carbon nanomaterials (CNM). In agreement with the fact that the PNS has a set of various functions, its remarkable ability to change the program and participation purpose as PCNR is disclosed. Such readjustments allow affecting the properties of the synthesized compositional materials. The main attention in the work is paid to theoretical analysis of the conditions, under which PCNR gains the ability to control the nanotechnology, the production of diamonds.