Home – Home – Jornals – Chemistry for Sustainable Development 2008 number 3

Using the modified procedure of the synthesis of non-stoichiometric hydroxyapatite species at the physiological pH and solution temperature, we obtained the solid phases with the Ca/P atomic ratios within the range from 1.58±0.01 to 1.67±0.01. According to the data of X-ray phase an alysis, these samples are composed of hydroxyapatite. The effect of inorganic additives (phosphate, oxalate, carbon ate anions, magnesium cations) and organic ones (amino acids) on the crystallization of hydroxyapatite was studied.

The electrokinetic properties of the sol of synthesized hydroxyapatites of different stoichiometric composition were studied. It was established that the charge and the value of î potential of hydroxyapatite particles depend on the Ca/P atomic ratio. It was discovered that the character of amino acid interaction with non-stoichiometric hydroxyapatite differs from that with the stoichiometric one. It was shown that adsorption observed on the samples of synthesized hydroxyapatite is described within Langmuir and Freundlich models.

Radiation impact on plants Pentaphylloides fruticosa (L.) O. Schwarz has been studied. It has been established, that the radiation factor pressure initiates adaptation processes affecting the growth and development of plants, as well as physiological and biochemical reorganization of the metabolic processes determining population existence in a habitat. It is experimentally demonstrated that the biosynthesis of the total content of flavonoids in Pentaphylloides fruticosa leaves is intensified under radiation impact. It is revealed that the content of flavonols (both total and in groups) in P. fruticosa leaves demonstrates a 2.3-fold increase as compared to the reference, and at the same time the difference against the reference increases with the increase in the contamin ation level. Individual flavonoid components have been shown to form different types of response to radiation influence in an organism. The content of hyperosyde, quercitrin and kaempferol decreases with the increase in radiation contamin ation, the content of other flavonoid components, on the contrary, increases. The qualitative flavonoid content in leaves of both irradiated and reference plants remains constant. Phenomen a of leaf surface reduction, a lengthwise decrease in the annual spear and leafstalk gain, an increase in the number of leaves on a spear. It has been found that with the increase in irradiation the differences against the reference increased according to the majority of criteria. Different organs of Pentaphylloides fruticosa exhibit different accumulative ability with respect to radionuclides: the content of 90Sr in leaves is higher compared to that in stems irrespective of the level of contamin ation, whereas for 137Cs such a correlation is not observed.

Elemental composition of 30 samples of oral liquid from four groups of patients living in the Omsk Region was investigated by means of atomic emission spectral an alysis with inductively coupled plasma.

Comparative an alysis of the composition of saliva for patients with different diseases of oral cavity showed that the elemental composition is specific in each case. It was established that the diagnostics of the corresponding diseases may be carried out on the basis of the data on the ratios Ca/P and Na/K. It was discovered with the help of mathematical statistics that the distribution of microelements Zn, Cu, Fe, Mn, Al also has group-related features.

New technology of bromine recovery from bromine-containing brines is proposed. The technology is based on the anode decomposition of metal chloride, oxidation of bromine with escaping chlorine, extraction transfer of bromine from the anode electrolyte to the recycle catholyte and reduction of bromine on a porous cathode. Commercial products of the proposed method are individual salts of bromine. It was demonstrated that the develop process is safe and involves low energy and reagent consumption.

The application of numerical methods to the investigation of combustion processes, including the use of tracer elements in numerical modelling, is considered. On the basis of the analysis of the numerical data obtained, conclusions related to explosion safety are made, in connection with inhibition, experimental determination of the rich limit of flame propagation, and determination of the final pressure after self-ignition in a closed vessel.

The process of aerosol formation during aldehyde photolysis is investigated. It is shown that atmospheric aldehydes serve as an efficient source of organic aerosol. Measurements of aldehyde concentrations in urban atmosphere were carried out, the scale of aerosol formation processes was characterized. It was established that the possibility of photochemical aerosol formation cannot be neglected in adequate estimations of the ecological consequences of atmospheric pollution with organic compounds.

A procedure for the determination of low-volatile impurities in the atmosphere is developed for the concentrations below 1 ng/m³. The method is based on the absorption of molecules and their clusters by water fog generated during sharp cooling of the atmospheric air with the evaporating liquid nitrogen. The developed experimental set-up was called drop concentrator. A simple and rapid method of calibration of the equipment was developed. It was shown that the error of vapour concentration measurement suing this method does not exceed 10 % within the range of mass concentrations 10 to 3000 ng/m³. The results of tests of the set-up under laboratory and field conditions are presented. The diurnal and seasonal dynamics of the concentration of aerosol-forming compounds and their connection with changes of meteorological parameters, source characteristics are considered.

An approach to the investigation of the effect of supramolecular structures on the photo-induced radical processes is proposed. The possibilities of the new approach are demonstrated with the example of the investigation of the host-guest type complex formation with biologically significant photoactive molecules with β-cyclodextrin; the investigation was carried out both by means of spin chemistry and with the help of laser pulsed photolysis. It was shown that the effect of complex formation is exhibited for geminal processes and fort he processes taking place in the volume and participated by radical particles. Investigation of spin and molecular dynamics in these processes will allow one to establish the mechanisms of molecular recognition and the nature of selectivity in biological processes.

A comparative analysis of a number of physicochemical parameters of the initial and melted water obtained as a result of freezing - melting is carried out. These parameters include concentrations of organic, inorganic impurities and dispersed phase particles, as well as heavy isotopes of water, hydrogen peroxide, dissolved gases - oxygen, carbon dioxide. It is shown that melted water differs in these parameters from the initial water; the differences have a permanent and time-dependent character.

With the help of freezing - melting procedure, the efficiency k_pur of water purification from phenol is investigated as a dependence on the fraction of frozen solution (g) and freezing temperature T (freezing rate). The following kinds of dependencies are established: 1) a monotonous increase in k_pur with an increase in g at T = -3.5, -6.5, -10, -15 ^oC; 2) an increase in k_pur with an increase in the fraction of frozen aqueous solution to g ≈0.2, followed by a decrease, at freezing temperatures -20 and -25 ^oC (non-monotonous dependence). The influence of reasons preventing high k_pur (veiling the purification factor) is discussed. These reasons include the impossibility to separate the solution adhered to the ice surface from ice itself due to the sampling procedure (distorting factor) and trapping the impurities into the interdendritic cavities on the surface of the crystallization front (polluting factor). It is concluded that the most optimal technological conditions for the use of freezing for water purification is freezing at the crystallization front rate about 0.2 cm/h until the value of g ~ 0.5 is achieved.

Chemical substances existing in the finely dispersed phase state (as small aerosol particles 0.1-10 μm in diameter and as very thin films with a thickness of 0.01-1 μm) exhibit specific chemical and physicochemical properties. The processes characteristic of these substances are essentially different from the processes in relatively coarsely dispersed aerosol and thick films, and even more different from the reactions taking place in usual liquid or solid solutions. This specificity is connected with the fact that the rate of evaporation, solidification and layering of a dispersed substance exhibits a reciprocal square dependence on the size of dispersed particles. In turn, this causes essential differences in the volume structures of the chemical material for fine- and coarse-dispersed objects and therefore different mechanisms of chemical reactions occurring in them.

The absorption of formaldehyde from the gas phase by the plants of Ficus genus is investigated. The species promising for application in phytodesign for the purpose of indoor air purification from formaldehyde are revealed.