In porous or disperse media, the temperature and interfacial behaviors of water and solutions could be strongly affected by confined space effects (CSE). The surface nature of solids could influence the interfacial phenomena including both CSE and cryoscopic effects caused by the colligative properties of solutions. Strong changes in the characteristics of adsorption liquid layers, especially in narrow pores, are also caused by decreasing solvent activity. Therefore, it is of interest to compare the behaviors of water and NaCl solutions under CSE caused by hydrophilic and hydrophobic sorbents. Here, hydrophobic (AM–1) and hydrophilic (A–300) fumed silicas are used as representatives of disperse sorbents with different surface structure and characterized by textural porosity. This porosity is caused by voids between nonporous nanoparticles (NPNP) forming aggregates, agglomerates of aggregates, and visible particles (supra-NP structures) in the powders of low bulk density. Initial materials and related treated systems with bound water and NaCl/water were studied using nitrogen adsorption, microscopy, X–ray diffraction, infrared spectroscopy, thermogravimetry, rheometry, nuclear magnetic resonance spectroscopy, and quantum chemistry. Water bound to fumed silicas with or without NaCl could be assigned to several types: weakly (WBW, frozen at 260 K < T < 273 K) and strongly (SBW, frozen at T < 260 K) bound waters; weakly (WAW, chemical shift of dH = 0.5 – 2 ppm) and strongly (SAW, dH = 4 – 6 ppm) associated waters. WAW is not observed for A–300 systems. Additionally, in the systems with water/NaCl, there is frozen (immobile) water characterized by melting delay (T > Tm) at 273 K < T < 287 K (metastable water, MSW). The MSW appearance may be explained by release (with certain kinetic delay) of water trapped in NaCl crystallites dissolved at T > Tm = 273.15 K upon increasing amounts of liquid water with increasing temperature. The difference in the CSE in voids in hydrophobic and hydrophilic supra-NP structures onto bound water could be explained by the surface (–O)2Si(CH3)2 functionalities enhancing the clusterization of water bound to AM–1. As a whole, the difference in the surface nature of AM–1 and A–300 affects: (i) the NaCl crystallite size distributions; (ii) melting/crystallization temperatures of NaCl; (iii) viscosity and torque vs. shear rate (strain); (iv) temperature and interfacial behaviors of water alone and NaCl solutions at 215 – 287 K; and (v) effects of dispersion media influencing bound water. Obtained results are of interest not only from a theoretical point of view but also from a practical one since both silicas are used as components of composites containing water and NaCl (or other salts) in various practical applications in medicine, agriculture, etc.

The results of theoretical modeling of the spatial structure and electronic absorption spectra of isolated small particles of polymorphic modifications of lead monoxide - litharge and massicot, which are characterized by the presence of hypercoordinated atoms, have been analyzed. The optical properties of many oligomers of lead oxide are systematically considered in the work. The results of quantum chemical calculations by the methods of electron density functional theory (DFT and TDDFT) on the spatial structure and energy characteristics, as well as the electronic absorption spectra of the considered models, are discussed. Theoretical results are compared with available experimental data. The calculation method used and the proposed cluster models with or without attached (chemisorbed) water molecules allow us to reproduce the spatial structure and energy characteristics of polymorphic modifications of lead oxide at a semi-quantitative level. It has been found that the addition of water molecules to models for α-lead oxide nanoparticles contributes to their stabilization. The calculated values of the cohesion energy for litharge nanoparticles are greater than those for massicot ones, which corresponds to the experimental data for lead monoxide crystals. The calculated electronic spectra of the litharge nanoparticle models are characterized by absorption bands which lie in the region that corresponds to the red color, and those of massicot relate to yellow; the corresponding values of the width of the energy gap for the litharge models are smaller than for the massicot ones, which is consistent with the experimental data for crystals. The results of calculations show that the presence of hydroxyl groups in nanoparticle models leads to a hypsochromic shift of absorption maxima, so that with a sufficient number of such groups, these species may lose their color.

Oxides of tetravalent elements are well known to have a lot of crystalline modifications. For example, most of silica polymorphs are characterized by tetrahedral coordination environment of silicon atoms. On the contrary, crystals of stishovite and of some silicate minerals have their silicon atoms in octahedral coordination spheres. It has been found experimentally that the phase transitions between silica polymorphs accompanied by a rearrangement of silica-oxygen tetrahedrons into octahedra require an energy income (preference energy) of 54 kJ/mol. When increasing the atomic mass of the oxide forming element, the former decreases extremely and for tin dioxide is equal to -59 kJ/mol. These values can be reproduced in a theoretical way, within the frameworks of modern quantum chemical methods and periodic models. High disperse silica nanoparticles (as well as those for other oxides) have only the nearest order of atomic stationing, so that theoretical approaches developed for crystals cannot be applied to small particles. These particles can be transformed into stishovite form under hydrothermal conditions. Such a process can be simulated within cluster approximation by use of molecular models. This work is devoted to quantum chemical simulation of formation of the fragments with hexa-coordinated atoms of silicon and of its analogs in the structure of oxane dendrimers. A row of high symmetry models was examined containing two, three, five, and seventeen atoms of silicon and of germanium, titanium and tin, terminated with hydroxyl groups. These structures can be rearranged into another ones including oxide forming atoms with elevated (equal to 5 or 6) coordination number, so mimicking the rutile-like structure. Such models let it possible to fulfill the procedure of transformation without rupturing siloxane bonds, so remaining within a deformation approach. Another advantage is the exclusion of the basis set superposition error due to use of molecular models of the same total formula for all the coordination states. All calculations were carried out by Hartree-Fock and density functional theory methods with the all-electron (3-21G*) and valent (SBKJC) basis sets by means of the GAMESS program. Models of various size have been examined, in particular, disiloxane (HO)3Si-O-Si(OH)3 witch can be transformed into a self-coordinated form where one of silicon atoms becomes a five-coordinated; trisiloxane (HO)3Si-O-Si(OH)2-O-Si(OH)3 can be rearranged into symmetric isomer with one hexa-coordinated silicon atom. Pentasiloxane with neo-structure of [(HO)3Si-O]4Si forms three coordination structures, the most stable of them mimicking the stishovite crystal; it contains one 6-coordinated and two 5-coordinated silicon atoms. Siloxane containing 17 silicon atoms has a super-neo-structure of {[(HO)3Si-O]3Si-O}4Si; it includes seven six-coordinated and four five-coordinated silicon atoms. Relative models for silicon analogs have been also examined. When analyzing a dependence of the energy differences between open and coordinated oxane structures on the number of atoms of the oxide forming element in the cluster, one can jump to the conclusion that the specific value of this characteristic monotonously decreases with the increase in the number of atoms of the molecular model, so becoming close to the experimental data.

Метою даної роботи є оцінка енергетичної сприятливості утворення різних молібдатних груп (≡Si‑O‑)2Mo(=O)2 та =Si(‑O‑)2Mo(=O)2 під час термічно ініційованого диспергування MoO3 на гідроксильованій поверхні SiO2. Для цього було здійснено квантовохімічне моделювання реакції O12Si10(OH)16 + MoO3 = O12Si10(OH)14O2MoO2 + H2O в температурному інтервалі 300–1100 K із використанням обмеженого методу Хартрі-Фока (наближення ЛКАО) з валентним базисом SBKJC (Stevens-Basch-Krauss-Jasien-Cundari). Кластер O12Si10(OH)16, який являє собою структурний фрагмент кристала β‑кристобаліту, був використаний як модель високогідроксильованої поверхні кремнезему. Ми розглянули дві структури молібдатних груп (≡Si‑O‑)2Mo(=O)2, прикріплених до кремнеземного кластера O12Si10(OH)16 через силанольні групи. Молібдатні групи (Etot ‑584.60147 Hartree), прикріплені до кремнеземного кластера через віддалені силанольні групи, виявляються більш енергетично вигідними, ніж молібдатні групи (Etot ‑584.56565 Hartree), прикріплені до кремнеземного кластера через сусідні силанольні групи. Енергія молібдатних груп =Si(‑O‑)2Mo(=O)2 (Etot ‑584.48399 Hartree), прикріплених до кремнеземного кластера O12Si10(OH)16 через силандіольні групи, менш енергетично вигідні в порівнянні з подібними групами, прикріпленими через силанольні групи, через більше напруження кута між зв’язками. Знайдено, що реакція O12Si10(OH)16 + MoO3 = O12Si10(OH)14O2MoO2 + H2O в температурному інтервалі 300–1100 K, змодельована шляхом квантовохімічних розрахунків, свідчить, що процес диспергування MoO3 на гідроксильованій поверхні SiO2 є енергетично вигідним. Експ The aim of the present work is to evaluate the energetic favourability of the formation of different molybdate species (≡Si‑O‑)2Mo(=O)2 and =Si(‑O‑)2Mo(=O)2 during the thermally induced MoO3 dispergation on hydroxylated SiO2 surface. In order to do this a quantum chemical modelling of the reaction O12Si10(OH)16 + MoO3 = O12Si10(OH)14O2MoO2 + H2O within the temperature interval of 300–1100 K was undertaken using the Restricted Hartree-Fock method (the LCAO approximation) with the SBKJC (Stevens-Basch-Krauss-Jasien-Cundari) valence basis set. The cluster O12Si10(OH)16 which represents a structural fragment of a β‑cristobalite crystal was used in this work as a model of highly hydroxylated silica surface. We considered two structures of molybdate (≡Si‑O‑)2Mo(=O)2 species attached to O12Si10(OH)16 silica cluster via silanol groups. Molybdate species (Etot ‑584.60147 Hartree) attached to silica cluster via distant silanols appeared more energetically favourable than molybdate species (Etot ‑584.56565 Hartree) attached to silica cluster via nearby silanols. The energy of molybdate =Si(‑O‑)2Mo(=O)2 species (Etot ‑584.48399 Hartree) attached to O12Si10(OH)16 silica cluster via silanediol group is less favourable energetically in comparison with those attached via silanol groups because of higher bond angle straining. The reaction O12Si10(OH)16 + MoO3 = O12Si10(OH)14O2MoO2 + H2O in the temperature interval of 300–1100 K which simulates by quantum chemical calculations the dispergation of MoO3 on hydroxylated SiO2 surface was found to be energetically favourable. The experimentally optimised temperature of ca. 800 K required for dispergation of MoO3 on hydroxylated SiO2 surface is determined by MoO3 evaporation and transportation via the gas phase. ериментальна оптимальна температура (близько 800 K), потрібна для диспергування MoO3 на гідроксильованій поверхні SiO2, визначається випаровуванням та перенесенням MoO3 в газовій фазі.

Boron carbide (BC, B15-xCx B4C) has a unique combination of properties. This makes it a material for priority applications for a wide range of engineering solutions. The high melting point and heat resistance of the compound contribute to its use in refractory conditions. Due to its extreme abrasion resistance, B4C is used as an abrasive powder and coating. Due to its high hardness and low density, B15-xCx has ballistic characteristics. It is usually used in nuclear programs as an absorbent of neutron radiation Boron carbide ceramics (B15-xCx or BC) may lose strength and toughness due to the amorphization effect under high shear stresses. Aluminum dodecaboride AlB12 or B12Al, as well as boron carbide B12 [(CCC) x (CBC) 1-x] have common structural units B12 family of boron-icosahedral structures. The bond between icosahedrons is mainly due to atoms (Al, Si, O) or chains (CMC), where M is Al, Si, B, C. Doping BC powder with a small amount of AlB12, in cases of shock-shear stress, triggers the mechanism of "micro-cracking". Micro cracks and pores are formed in ceramics. The breakdown voltage decreases. AlB12 synthesis is associated with known difficulties. On the other hand. The production of metal-ceramic materials for several decades is associated with the interaction of liquid aluminum and boron nitride. The calculation of this reaction shows that it is exothermic. Avoiding oxidation in vacuum, the reaction occurs through the formation of aluminum nitride and aluminum dodeca-boride. In contrast to the liquid state, the process continues until the end, at conditional temperatures of evaporation of aluminum with slight changes in vacuum. The reaction product is a mixture of nanosized AlN/AlB12 powders with a weight ratio of 3/1 ready for baking without grinding. The acid-base properties of the nanosized powder mixture AlN + AlB12, the products of the interaction BN + Al in vacuum, which are used optionally, emit separate in pure phases of aluminum nitride and aluminum dodeca-boride. The yield of AlB12 is ~ 25%, boron reaches ~ 100%. The average particle size of the AlB12 powders according to TEM and ACS X-rays (area of coherent X-rays scattering), L (nm) is LTEM=110-150nm, LACS=51-70nm. The average specific surface area of the powder according to BET, TEM and ACS, SBET.m2/g=21,0-15,0; STEM.m2/g=21,4-15,4; SACS.m2/g=46,1-33,6; (at 1460 and 1640K, respectively).

Bone tumor diseases are one of the main problems in modern clinical practice. After surgery, some of the tumor cells capable of proliferation may remain, leading to tumor recurrence. In addition, surgical ablation of bone tumors creates bone tissue defects. Therefore, the problem of manufacturing specific biomaterials with a dual function of treating bone tumors and regeneration of bone defects has become a priority. The use of methods of targeted delivery and local controlled release of drugs contributes to the creation of the desired therapeutic concentration of drugs in the disease focus and increases their bioavailability. In recent years, promising samples capable of effective controlled release have been developed in which cisplatin, doxorubicin and gemcitabine have been used as model chemotherapeutic drugs. These approaches have been promising and have shown the potential to destroy residual tumor cells, however, they may become resistant to such drugs, which leads to treatment failure. The main purpose of the review is to summarize the latest world experience in the synthesis, research and use of composites based on bioactive ceramic materials and modern antitumor drugs as promising implants, embodying a new generation of complex remedies for targeted delivery with osteoconductive and antitumor properties, prolonged action, for local application. Examples are given of bioglass application with cytotoxic / cytostatic components, as well as results of development of the newest directions of antitumor therapy of bones, in which acquisition of resistance of tumor cells is not observed. The antitumor functions of such multifunctional samples are performed, for example, by chemotherapy, photothermal therapy, magnetic hyperthermia, and photodynamic therapy. These data are of scientific, practical and methodical interest.

It has long been known that materials containing cellulose fibers in their composition are destroyed by molds, microorganisms, actinomycetes, which use cellulose as a carbon source. Different fibrous materials to varying degrees (but always) are affected by molds. It is known that linseed and cotton types of paper are affected by the smallest number of fungi, and sulphate ones by the largest. The most biostable is cotton paper, the composition of which contains chalk in a sufficiently large amount. The observations carried out by the authors showed that the highest biostability (fungal resistance) is characteristic of papers containing chalk and kaolin, the lowest is glued types of paper with a high degree of sizing. Aging of paper with increasing temperature increases the overall susceptibility of all types of paper tested without exception. Obviously, changes in the physical and chemical properties of paper as a result of aging create more favorable conditions for the growth of fungi. It is well known that paper can serve as a medium for the spread of infectious diseases. The authors of the article studied the thermo-physical properties of basalt fiber and investigated the possibility of using it for the manufacture of heat-insulating technical paper.Obtaining materials that are not affected by bacteria, insects and molds (fungicidal,insecticidal) can be solved by using inorganic fibers, which are obtained from almost unlimited natural resources and which have excellent biochemical properties. It should be noted that the concept of "biocidal" paper (material) is collective. It combines species that differ in their ability to kill bacteria (bactericidal), molds (fungicidal), insects (insecticidal). Each of the biocidal types of materials has two or more of these properties.

The morphological and textural characteristics of various silicas (93 fumed silicas and 56 porous silicas), different carbons (230), and porous polymers (53) are analyzed using probe (nitrogen, argon, benzene, n-decane, water) adsorption, small angle X-ray scattering (SAXS), and transition (TEM), scanning (SEM) electron and atom force (AFM) microscopies. There are certain correlations between pore volume (Vp) and specific surface area (SSA, SBET) for these materials. Synthesis and treatment temperatures affect this relationship since a linear Vp - SBET approximation scatter decreases with decreasing these temperatures. Silicas are composed of nonporous nanoparticles (NPNP), but activated carbons (AC) are composed of porous nanoparticles (PNP). For different materials, NP are weakly or strongly packed in secondary structures. However, there are general features of pore size distributions (PSD) for NP-based materials, e.g., minimal contribution of narrow mesopores of 3-5 nm in radius due NP-packing effects. For AC produced using the same chars and activation agents but with varied activation time, the textural characteristics demonstrate smooth changes with increasing burn-off degree: nanopores partially transform into narrow mesopores with opposite PSD shifts of broad mesopores and macropores. Comparison of adsorption (open pores accessible for probes) and SAXS (both open and closed pores) data for carbons shows that the difference decreases with increasing burn-off degree due to decreasing contribution of closed pores. Most clear pictures on the particulate morphology and texture could be obtained in parallel analysis using adsorption, SAXS, and microscopic methods with appropriate data treatments.

In this work, we investigated granular and powder activated carbons (AC) – initial and waste with adsorbed impurities after purification of technical glycerin and subsequent washing with water. The aim of this work was to quantify the adsorbed impurities in the spent AC using thermal analysis (TA) and to work out the conditions for thermal regeneration of AC. TA of AC samples was carried out in an atmosphere of helium and air; the specific surface area of AC was measured by the method of low-temperature desorption of argon (SAr). It was established by the TA method that water is released in the temperature range of 20 – 170 °C, and glycerin – 170 – 400 °C. Spent AC contains up to 22.8 wt. % H2O and up to 44.6 wt. % C3H5(OH)3. Based on these data, it was proposed to regenerate spent coal by heating at 400 °C in air. In the case of a granular AC sample, the regeneration proceeds completely, while for a powder AC sample, the specific surface area with respect to argon is restored only by 22 %, from the initial 2170 m2/g. The adsorption isotherms of methylene blue (MB) of the initial samples are located higher than for the spent ones, since in the spent ones part of the surface is occupied by adsorbed glycerin. The SMB values calculated from the adsorption of methylene blue in the spent AC samples are strongly overestimated in comparison with SAr. Probably, MB displaces glycerin from the surface or interacts with it to form complexes.