An efficient method has been developed for the synthesis of siloxane aerogels with a hybrid structure built into the polymer structure. At the initial stage, a gel was obtained by polycondensation of tetraethoxysilane and ferrocene-containing alkoxysilanes, catalyzed by BF3 ⋅ Et2O in acetone. The transformation of gels into aerogels was performed using supercritical carbon dioxide (SC-CO2). The aerogel samples were characterized in detail by Mössbauer spectroscopy and nitrogen adsorption methods, and the density of the materials was determined. The iron content in the resulting aerogels varied from 3.6 to 8.7 wt

An efficient method has been developed for the synthesis of resorcinol–formaldehyde hybrid aerogels with ferrocene subunit fragments embedded in their polymer structure. For gelation preceding the synthesis of aerogels, dioxane was used for the first time as the main reaction solvent. The gels were converted into aerogels using SC-CO2. The aerogel samples were characterized in detail by Mössbauer spectroscopy, nitrogen adsorption, and atomic absorption spectroscopy. The density of the materials was determined. The iron content in the resulting aerogels varies from 1.5 to 11 wt

The reaction of ferrocene-containing alkenes and alkynes with HSi(OEt)3 and HSiMe(OMe)2 in the presence of Karstedt catalyst (Pt2[(Me2SiCH=CH2)2O]3) was studied. It was found that only terminal alkenes underwent hydrosilylation, while alkynes entered this reaction even in the case of a disubstituted C≡C bond. The synthesized silicon-containing ferrocene derivatives were used as precursors for the preparation of siloxane aerogels, which were characterized by low-temperature nitrogen adsorption, scanning electron microscopy, and Mössbauer spectroscopy.

Из плодового тела трутового гриба Fomes fomentarius методами суб- и сверхкритической флюидной экстракции этанолом получены хитинсодержащие комплексы с выходом 57—88 % и содержанием хитина до 18,7 %. Оценено влияние продолжительности, температуры и давления экстракции на выход и свойства получаемых хитинсодержащих комплексов, которые охарактеризованы по элементному и функциональному (ИК-спектроскопия) составу. Показана высокая сорбционная емкость полученных комплексов по отношению к основному — метиленовому синему (ло 312 мг/г) и кислотному — конго красному (до 170 мг/г) красителям, что указывает на полиамфолитную природу полученных комплексов — биосорбентов. Chitin-containing complexes were obtained from the fruiting body of the tinder fungus Fomes fomentarius using sub- and supercritical fluid extraction with ethanol with a yield of 57—88 % and a chitin content of up to 18.7 %. The influence of the duration, temperature, and pressure of extraction on the yield and properties of the resulting chitin containing complexes has been evaluated. Chitin-containing complexes were characterized by elemental and functional (by IR spectroscopy) composition. The high sorption capacity of the obtained complexes in relation to the basic — methylene blue (up to 312 mg/g) and acid — congo red (up to 170 mg/g) dyes is shown. Sorption activity relative to both basic and acid dyes indicates the polyampholytic nature of the resulting complexes-biosorbents.

Series of compounds Ni3 – xMTe2 (M = Sb, Sn; x = 0–1) were obtained by high-temperature sealed-tube synthesis and characterized by X-ray powder diffraction and 121Sb and 119Sn Mössbauer spectroscopy. For Ni3–xSnTe2, it was shown that, as х varies from 1 to 0, nickel is distributed over three possible sites, two of which give a total occupancy of 1 and have ordered vacancies. Meanwhile, for Ni3–xSbTe2 and х other than 0.9–1.0, the vacancy ordering disappears. The temperature dependence of the presence or absence of vacancy ordering was established for Ni2SbTe2; the ordering disappears on heating above 600°C and appears again on cooling.

Series of compounds Ni3 – xMTe2 (M = Sb, Sn; x = 0–1) were obtained by high-temperature sealed-tube synthesis and characterized by X-ray powder diffraction and 121Sb and 119Sn Mössbauer spectroscopy. For Ni3–xSnTe2, it was shown that, as х varies from 1 to 0, nickel is distributed over three possible sites, two of which give a total occupancy of 1 and have ordered vacancies. Meanwhile, for Ni3–xSbTe2 and х other than ~0.9–1.0, the vacancy ordering disappears. The temperature dependence of the presence or absence of vacancy ordering was established for Ni2SbTe2; the ordering disappears on heating above 600°C and appears again on cooling.

A facile approach to the preparation of magnetic nanoparticles based on the oxide or oxide-hydroxide of chemically inert iron species (Fe3+ ions) stabilized with a polymer shell was proposed. The polymer matrices used for this purpose were the macromolecules of sodium alginate, a natural anionic polysaccharide, and a synthetic polymer preliminarily converted to microgel using N-bis-isopropylacrylamide containing polyacrylic acid (PAA) units. When sodium alginate is used for stabilization, iron oxide nanoparticles (maghemite) are formed, while in the presence of PAA-containing microgels, iron oxide-hydroxide nanoparticles (akageneite) are obtained.

The polycondensation sol–gel reaction of 5-methylresocinol and formaldehyde with additional compounds in reaction media is a relatively simple way to produce modified aerogels. In order to obtain aerogels with a large surface area and high porosity, the conditions for gel formation, the solvent exchange process before drying, and the supercritical drying process were optimized. A successful attempt was made to introduce ferrocene units into 5-methylresocinol-formaldehyde-based aerogels. The resulting aerogels are amorphous substrates, and no aggregated ferrocene units were found in their structures. All of the aerogel samples that were obtained are structurally similar despite differences in the original ferrocene units and their initial concentration. It was found that the inclusion limit of ferrocene structural blocks into an aerogel is ~6% wt. The structures of the inclusions in which all of the Fe atoms in the aerogel substrates were present in ferrocene/ferrocenium at an approximate ratio of 60/40 to 55/45 were confirmed by X-ray photoelectron spectroscopy and Mössbauer spectroscopy. Aerogels with ferrocene/ferrocenium inclusions are likely to exhibit reversible redox activity in reactions with gaseous reagents.

Growth factors (GFs) are endogenous signaling proteins, that regulate cell migration, proliferation and differentiation in tissue regeneration. GFs’ concentrations in chronic wounds are pathologically reduced. This leads to a disruption of the healing process and makes chronic wounds treatment more complicated. There are drugs currently used in clinical practice, that contain GFs in a free form. However, their efficiency for chronic wounds treatment is limited, as GFs are quickly degraded in a proteolytic environment of chronic wounds. In order to overcome this limitation biocompatible molecular systems for targeted delivery and controlled release are proposed, such as: micro- and nanoparticles, hydrogels, scaffolds. GFs roles in the healing process, chronic wounds pathophysiology and molecular systems for GFs targeted delivery and controlled release are reviewed.

Multiliposomal containers obtained by the successive adsorption of cationic polypeptide poly(L-lysine) and anionic liposomes on the surface of anionic magnetic microgels—the products of γ-Fe 2 O 3 (maghemite) synthesis in the matrix of natural anionic polysaccharide—the mixed Na/Ca salt of alginic acid—are presented. The composition and morphology of magneto-sensitive microgels are studied by X-ray analysis, FTIR spectroscopy, Mössbauer spectroscopy, magnetometry, and transmission electron microscopy. The size of particles of multiliposomal containers with the ultimate liposome content in the physiological solution is about 400 nm. They are not cytotoxic up to a poly(L-lysine) concentration of 600 μM. It is shown that these objects filled with antitumor antibiotic—doxorubicin—are able to move in a suspension under application of an external magnetic field with the integrity of liposomes in the container being preserved. The obtained containers are promising for the controlled delivery of bioactive substances (drugs).

Ferroelectric single crystals exhibit the largest known piezoelectric constants and therefore show high potential for application in electronic devices, including sensors, actuators, and transducers. Their large properties, however, can only be fully exploited if the behavior is not influenced by lattice defects, formed during high-temperature processing. Such defects can inhibit domain-wall movement, increase leakage currents, and are predominantly responsible for the poor performance of the emerging ferroelectric crystals. Here, an approach to considerably enhance the piezoelectric and ferroelectric properties of (K,Na,Li)(Nb,Ta,Sb)O3 crystals by oxygen annealing is investigated. As compared to the non-annealed crystals, polarization, strain, and piezoelectric constant of the annealed sample were enhanced by a factor of two, resulting in an outstanding room-temperature value of piezoelectric constant d33 = 732 pC/N and a peak value of d33 = 1431 pm/V at the orthorhombic-tetragonal transition. The behavior was analyzed using electromechanical measurements, Mössbauer spectroscopy, and impedance spectroscopy, revealing decreased concentrations of both oxygen vacancies and Sb3+ ions after annealing. The findings indicate that the control of the defect chemistry enables these ferroelectric (K,Na)NbO3-based single crystals to outperform their polycrystalline counterparts and reach the values of lead-containing compositions. Moreover, the present strategy enables further detailed studies of the inherent crystal anisotropy and the possibilities for domain engineering.

The one-step synthesis of water-soluble composites from maghemite (γ-Fe2O3) nanoparticles with a diameter of 12 ± 4 nm and a biocompatible polysaccharide, namely, sodium salt of carboxymethyl cellulose, is described. The role of the polymer matrix consists in stabilization of the resulting nanoparticles by the electrostatic interaction of polymer carboxyl groups with the surface atoms of iron in the (3+) oxidation state. The dissolution of the composites in water affords aggregatively stable dispersions responding to the external magnetic field. The content of the magnetic phase (iron oxide) in the formulation of the maghemite–carboxymethyl cellulose composite is defined by the ratio of components during the synthesis.

Current advances in diabetic foot ulcers (DFU) treatment are discussed. Normal and pathological wound healing process are observed and the role of growth factors (GFs) is elucidated. Current techniques involving GFs and platelet rich plasma (PRP) are compared. Up-to-date research suggests that treatment with single growth factor (GF) could be insufficient and not encompassing all pathological changes in DFU bed. Efficiency of PRP is rather controversial and lacks evidence. Thus the use of cocktail of particular GFs is suggested. Pro et contra of each approach are discussed.

The electronic state and local surrounding of both iron ions and tin dopant ions in Lu 1 – x Ca x Fe 0.997 Sn 0.003 O 3 ( x = 0.003; 0.1; 0.2) compounds were studied by 57 Fe and 119 Sn Mössbauer spectroscopy. The analysis of 57 Fe spectra showed that in the Lu 0.8 Ca 0.2 Fe 0.997 Sn 0.003 O 3 sample, obtained by air annealing, the charge deficit created by the substitution of Lu 3+ by Ca 2+ was compensated by the partial transition of Fe 3+ to the +5 oxidation state. With a further increase in the value of x (in the Lu 0.8 Ca 0.2 Fe 0.997 Sn 0.003 O 3 compound) a mixed compensation mechanism appeared, including the formation of oxygen vacancies VO in addition to Fe 5+ ions. Annealing the sample with x = 0.1 in H 2 at 400°C led to the reduction of Fe 5+ to Fe 3+ and, accordingly, to the pure vacancy mechanism of the Ca 2+ charge deficit compensation. The analysis of 119 Sn spectra showed that the substitution of Lu 3+ by Са 2+ in the Lu 0.8 Ca 0.2 Fe 0.997 Sn 0.003 O 3 structure led to the increase in the value of the magnetic field H , probed by some Sn 4+ ions, as compared to the value of H > observed in the case of Lu 0.997 Ca 0.003 Fe 0.997 Sn 0.003 O 3 . This change can be explained by a local increase in the angle of the indirect exchange interaction in the chain Fe 3+ –О 2 ––Sn 4+ , reflecting the presence of Ca 2+ cation, larger than that of Lu 3+ , in the vicinity of Sn 4+ ion.