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To clarify the crystal chemical features of natural and synthetic oxalates Me2+(C2O4)∙2H2O (Me2+ = Fe, Mn, Mg, Zn), including minerals of the humboldtine group, solid solutions of lindbergite Mn(C2O4)∙2H2O–glushinskite Mg(C2O4)∙2H2O were precipitated under various conditions, close to those characteristic of mineralization in biofilms: at the stoichiometric ratios ((Mn + Mg)/C2O4 = 1) and non-stochiometric ratios ((Mn + Mg)/C2O4 < 1), in the presence and absence of citrate ions. Investigation of precipitates was carried out by powder X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Thermodynamic modelling was performed in order to evaluate the lindbergite–glushinskite equilibrium. It was shown that glushinskite belongs to the orthorhombic β-modification (sp. Gr. Fddd), while lindbergite has a monoclinic α-modification (sp. gr. C2/c). Mg ions incorporate lindbergite in much higher quantities than Mn ions incorporate glushinskite; moreover, Mn glushinskites are characterized by violations of long-range order in their crystal structure. Lindbergite–glushinskite transition occurs abruptly and can be classified as a first-order isodimorphic transition. The Me2+/C2O4 ratio and the presence of citric acid in the solution affect the isomorphic capacity of lindbergite and glushinskite, the width of the transition and the equilibrium Mg/Mn ratio. The transition is accompanied by continuous morphological changes in crystals and crystal intergrowths. Given the obtained results, it is necessary to take into account in biotechnologies aimed at the bioremediation/bioleaching of metals from media containing mixtures of cations (Mg, Mn, Fe, Zn).

Monohydrocalcite (MHC) is hydrated calcium carbonate, which plays an active role in many geological processes, carbonate biomineralization, and can be used for fundamental science (as a paleoenvironmental indicator) and industry (for removal of hazardous anions). Despite a great number of works, the conditions preferable for MHC formation/stabilization and MHC crystal chemical patterns in relation to Mg and H2O are not clarified yet. In the course of current work, we conducted 38 syntheses to obtain information on MHC formation at different Mg/Ca ratios (0–12), pH (~9–12), and temperature (23 and 3 °C). Newly formed carbonate precipitates were studied by means of X-ray powder diffraction, optical, and scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman, and Fourier-transform infrared (FTIR) spectroscopies. The phase diagram for MHC, calcite, aragonite, and dypingite as a function of pH and Mg concentration in solution at T = 23 °C and Ca/CO3 = 0.5 was obtained. We demonstrated that MHC could be stable in dry conditions for up to two years and that the time of crystallization is important for the transformation of amorphous calcium carbonate to MHC. Our results on synthetic MHC stability show that the widespread idea that MHC is a short-lived intermediate phase is wrong. For the first time, on the basis of a regular changes in the unit-cell parameters the possibility of significant incorporation of magnesium in MHC has been demonstrated. According to FTIR data, it is shown to be accompanied by an increase in the water content, which leads to multidirectional change in a and c MHC parameters.

Drug resistance and damage caused to the normal cells are the drawbacks which have limited the use of the existing effective anticancer drugs. Attainment of a steady and extended release by encapsulating dual drugs into biocompatible and biodegradable vehicles is the key to enable the use of these drugs for effective inhibition of cancer. In this study, carboxymethyl chitosan (CMCS), a proficient water-soluble derivative of chitosan has been synthesized using chemical route and used for the delivery of 5-Fluorouracil and doxorubicin individually as well as in combination. Carboxymethylation occuring at –NH2 and OH sites of chitosan, has been confirmed using FTIR. EDX and Fluorescence studies elucidate the encapsulation of 5-Fluorouracil and doxorubicin into CMCS. The capability of CMCS to release the drugs in a more sustained and prolonged manner is evident from the obtained release profiles. About 14.9 µg/ml is enough to cause 50% cell death by creating oxidative stress and effectuating DNA fragmentation. Amidst the existing reports, the uniqueness of this work lies in using this rare coalition of drugs for the suppression of breast cancer and in reducing the side effects of drugs by encapsulating them into CMCS, which is evidenced by the high hemocompatibilty of the samples.

The short-range order in Li–Al–(OH−, F−) tourmalines with Y[Li/Al] ≈ 1 and different Na/Ca ratio was investigated by means of bond valence theory, experimental IR spectroscopic data and the results of X-ray single crystal diffraction. The stability of the arrangements coordinating W- and V-crystallographic sites occupied by OH−, F− and O2− ions was refined. A unified model of assignment of absorption bands in the IR spectra to the local arrangements (clusters) was suggested taking into account the first and the second OH−coordination spheres. The types of local cation arrangements around the W- and V-anion sites, alongside with clusters ratio and their distribution were brought out. The short-range order in Li–Al tourmalines controlled not only by local restrictions of the bond valence theory, but also by the long-range order was described.

The present study is focused on the effect of biofilm medium chemistry on oxalate crystallization and contributes to the study of the patterns of microbial biomineralization and the development of nature-like technologies, using the metabolism of microscopic fungi. Calcium oxalates (weddellite and whewellite in different ratios) were synthesized by chemical precipitation in a weakly acidic environment (pH = 4–6), as is typical for the stationary phase of micromycetes growth, with a ratio of Ca2+/C2O42− = 4.0–5.5, at room temperature. Additives, which are common for biofilms on the surface of stone in an urban environment (citric, malic, succinic and fumaric acids, and K+, Mg2+, Fe3+, Sr2+, SO42+, PO43+ and CO32+ ions), were added to the solutions. The resulting precipitates were studied via X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). It was revealed that organic acids, excreted by micromicetes, and some environmental ions, as well as their combinations, significantly affect the weddellite/whewellite ratio and the morphology of their phases (including the appearance of tetragonal prism faces of weddellite). The strongest unique effect leading to intensive crystallization of weddellite was only caused by the presence of citric acid additive in the medium. Minor changes in the composition of the additive components can lead to significant changes in the weddellite/whewellite ratio. The effect of the combination of additives on this ratio does not obey the law of additivity. The content of weddellite in the systems containing a representative set of both organic acids and environmental ions is ~20 wt%, which is in good agreement with natural systems.

Tourmaline rare-earth element (lanthanides + Y) patterns could provide valuable geological information as tourmalines are the most abundant borosilicates on Earth and are stable at extreme PT conditions. The lanthanide-bearing tourmalines were synthesized for the first time in a series of high- (4 GPa) and low-pressure (0.2 GPa) hydrothermal experiments. We have found that Ln-content (Ln = La3+, Nd3+, Eu3+ and Yb3+) in synthetic tourmalines varies significantly (1.13–8.35 wt% Ln2O3) with Yb

The pattern of elements accumulation in biodeposits formed by living organisms and extracellular products of their metabolism (biofouling, primary soils) on different bedrocks (of the monuments of Historical necropoleis in Saint Petersburg) were studied by a complex of biological and mineralogical methods (optical microscopy, SEM, EDX, XRD, ICP MS, XRFS). The content of 46 elements in biodeposits with various communities of microorganisms is determined. The model recreating the picture of the input and selective accumulation of elements in biodeposits on the stone surface in outdoor conditions is assumed. It is shown that the main contribution to the elemental composition of biodeposits is made by the environment and the composition of the microbial community. The contribution of leaching under the action of microbial metabolites of mineral grains, entering biodeposits from the environment, is significantly greater than that of the underlying rock.

Pb-dominant tourmaline was synthesized at 700 °C and 200 MPa in two hydrothermal experiments in the system MgO-Al2O3-B2O3-SiO2-PbO-H2O (run OV-4-2) and MgO-Al2O3-B2O3-SiO2-PbO-CaONa2O-H2O (run OV-5-3), respectively. Run OV-4-2 forms needle-like (lengths up to 7 µm), lead-rich (up to 13.3 wt% PbO) crystals that are chemically homogeneous. Run OV-5-3 forms columnar (lengths up to 400 µm) crystals that are chemically zoned (Pb-rich cores, up to 14.7 wt% PbO, and Pb-poor rims, ~2 wt% PbO). Additional phases that form in trace amounts are Pb-feldspar, quartz, diaspore (in OV-4-2) and talc, mullite, spinel, quartz (in OV-5-3). Single-crystal structure refinement (SREF) of the central zone of Pb-rich tourmaline from the run OV-5-3 proves that Pb2+ cations occupy the X-site in the tourmaline structure. The unit-cell parameters of the studied tourmaline are: a = 15.9508(10) Å, c = 7.2024(6) Å. The formula derived from SREF results of this Pb-rich tourmaline is X(Pb0.63☐0.37) Y(Al1.71Mg1.29) Z(Al5.04Mg0.96) T(Si6.00O18) (BO3)3V(OH)3.00W(O1.00). Accordingly, the studied crystal is a Pb-analog of hypothetical “oxy-uvite,” and thus referred to here as “Pb-oxy-uvite.” Similarities between (1) the paragenesis of Minh Tien tourmaline, and (2) the final experimental phase assemblages observed here, indicate comparable P-T conditions of formation.

Rock surfaces in natural systems are inhabited by multispecies communities of microorganisms. The biochemical activity of microorganisms and the patterns of microbial crystallization in these communities are mostly unexplored. Patterns of calcium carbonate and calcium oxalate crystallization induced by bacteria Bacillus subtilis and by B. subtilis together with Aspergillus niger on marble surface in vitro in liquid medium and in humidity chamber&mdash, were studied. Phase identification was supported by XRD, SEM, EDXS, metabolite composition was determined by GC&ndash, MS. It was found that the activity of B. subtilis&ndash, A. niger associations significantly differ from the activity of B. subtilis monocultures in the same trophic conditions. The phase composition and the morphology of the forming crystals are determined by the composition of the metabolites excreted by the microorganisms&mdash, particularly by the ratio of the concentrations of extracellular polymeric substances (EPS) and oxalic acid in the medium. The acidification activity of micromycetes may suppress the formation of bacterial EPS and prevent the formation of calcite. The present results can be used in the development of biotechnologies using microbial communities.

The influence of organic and inorganic components of biofilms with microscopic fungi on the phase composition and morphology of precipitating calcium oxalates has been experimentally investigated. It is established that biofilm components may facilitate the formation of metastable calcium oxalates (dihydrous weddellite and trihydrous caoxite) in the crystallization range of monohydrous whewellite. It is shown that the decisive role in the formation of weddellite crystals in biofilms is played, along with oxalic acid, by the citric acid released by micromycetes, Fe3+ ions from the environment entrapped by the biofilm, and the ratio of Ca2+ ions and oxalate ions. The transformation of bipyramidal habit of weddellite into bipyramidal‒prismatic habit may be caused by the presence of Mg2+ and $${\text{SO}}_{4}^{{2 - }}$$ ions in the crystallization medium.

Thermal stability, structural evolution pathways, and phase transition mechanisms of the calcium oxalates whewellite (CaC2O4·H2O), weddellite (CaC2O4·(2+x)H2O), and caoxite (CaC2O4·3H2O) have been ...

Tourmaline (the first natural pyroelectric material discovered) is the most common borosilicate on Earth characterized by a great variety of ionic substitutions at all structural sites. In this work the mosaicity and chemical inhomogeneity of single crystal samples of natural Fe-Mg and synthetic Ni- and Cu-rich tourmalines were characterized by X-ray diffraction (rocking curves, ω – 2θ scanning) and energy-dispersive X-ray spectroscopy. The iron oxidation state (Fe3+/ΣFe) in natural tourmalines was determined by Mӧssbauer spectroscopy. The pyroelectric properties of tourmalines were examined at room temperature by the dynamic pyroelectric measurement method. This approach allowed estimating the primary pyroelectric coefficient with the error smaller than ±0.15 μCm-2K-1. Based on the original and published data, it was shown that one of the main factors determining the pyroelectric properties of tourmaline is the ion oxidation state. It was found that the values of the Na-tourmaline pyroelectric coefficient were inversely proportional to the amount of divalent cations (Mg, Fe) and/or directly proportional to the amount of Al3+. This can be used for the directed synthesis of tourmalines with the required pyroelectric properties.

The role of cyanobacterial communities in the formation of carbonate sediments (ancient and modern) is not completely clear. We studied the cyanobacterial communities connected with carbonate sediments of the freshwater bodies feeding the historical Peterhof fountains (Saint-Petersburg, Russia). Cyanobacterial communities were studied by metagenome analysis and optical microscopy. Carbonates associated with cyanobacterial communities (both in situ and in vitro) were studied by powder X-ray diffraction analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy. The interconnection between the mineral composition of carbonate sediments and inhabiting microorganism species was established. The leading role of cyanobacteria in carbonate biomineralization in fresh water of Peterhof fountains water supply system was shown. Cyanobacteria of 24 genera were revealed in sediments composed of calcite and aragonite. The crystallization of carbonates on the surface of 13 species of cyanobacteria was found. Using model experiments, a significant contribution of cyanobacterial species of the Oscillatoriaceae family (Phormidium spp., Lyngbya sp., Oscillatoria formosa) to carbonate biomineralization is demonstrated.

Series of Eu-apatites were synthesized by precipitation from aqueous solutions with the Eu/Ca atomic ratio from 0.5% to 5% at T = 90 °C. Resulting precipitates were studied using different experimental techniques including X-ray powder diffraction, infrared and raman spectroscopy, scanning elecrton microscopy, EDX and photoluminescent spectroscopy. Eu-doped Ca-deficit nanosized non-stoichiometric hydroxyapatite with high water content has been obtained throughout the experiment. Europium content in the synthesized apatites reaches 0.24 apfu (Eu/Ca = 2.5%). Relations between Eu content is the solution and precipitate have been established. It was shown that Eu-monacite starts to precipitate as secondary phase at Eu/Ca ratio in starting solution 1% or higher. Maximum luminescence is observed in apatite with ∼2% Eu/Ca ratio (which equals to ∼0.2 apfu and corresponds to 3% Eu/Ca ratio in the starting solution). As an important and brand-new result, apatite with 2% Eu/Ca ratio can be considered as the most appropriate material for the producing biolabels for luminescent research in medicine and biology.

To study strontium (Sr) incorporation into calcium oxalates (weddellite and whewellite), calcium-strontium oxalate solid solutions (Ca,Sr)[C2O4]∙nH2O (n = 1, 2) are synthesized and studied by a complex of methods: powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy. Two series of solid solutions, isomorphous (Ca,Sr)[C2O4]&middot, (2.5 &minus, x)H2O) (space group I4/m) and isodimorphous Ca[C2O4]&middot, H2O(sp.gr. P21/c)&ndash, Sr[C2O4]&middot, H2O(sp.gr. P 1 - ), are experimentally detected. The morphogenetic regularities of their crystallization are revealed. The factors controlling this process are discussed.

The present paper contains a review of literature data on sources of singlet oxygen in lower atmosphere and methods of its registration. Singlet oxygen gas analyzer developed in OPTEC JSC (St Petersburg, Russia), which operation principle is based on the 9,10-definilantracene chemiluminescent reaction is described in the present paper. The new gas analyzer used for solving a wide range of fundamental and applied problems connected with the processes and phenomena at the boundary between biogenic and abiogenic nature. Its capabilities demonstrated on the examples for monitoring pollutant concentrations in atmospheric air, on the experiments in vivo and in vitro on recording singlet oxygen on the surface of snow and near plants infected by pathogenic fungus, as well as on tests of photocatalytic materials developed for use in medicine and in protection of architectural and sculptural monuments from biodeterioration.

The molecular water incorporation in bioapatites obtained by bone pyrolysis at temperatures of 600–1100 °C has been investigated using in situ solid 1H nuclear magnetic resonance (solid 1H NMR) method in the temperature range of T = 25–300 °C and, in addition, 1H magic-angle spinning NMR, X-ray diffraction and infrared spectroscopy at room temperature. For comparison, synthetic analogues of bioapatite, precipitated hydroxyapatite (HA), HA with La impurity and carbonate fluorapatite were investigated as well. It was established that there are water molecules adsorbed on crystallites surfaces and bound in structure (H2Os) in studied apatites. More rigid H2Os1 molecules cause the doublet under normal conditions and the wide singlet at T ≥ 150 °C in situ 1H solid NMR spectra. In addition, H2Os3 molecules with reorientation mobility at T = 150–300 °C are presented in bioapatite and HA annealed at lower temperatures and La-HA. Water incorporation into structure of bioapatite annealed at 600–1100 °C and its synthetic analogues HA is established to be zeolite-like. Presumably, the configuration of cavities is formed in the apatite crystal scaffold during annealing of studied apatites. These cavities are related with vacancy clusters in original structures and connected between themselves and with surface by the channels with a diameter of not more than 0.3 nm. Water molecules trapped in smaller (H2Os2) and larger cavities (H2Os1) cause the doublet and singlet, respectively; water molecules in OH vacancies in channels (H2Os3) are due to narrow lines.

The crystallization of calcium oxalates (weddellite and whewellite) by interaction of natural and synthetic apatites and fossilized tooth tissue with fungus Aspergillus niger, one of most active acid producers, was studied in vitro. The morphology and the sequence of formation of growing oxalate hydrate crystals were revealed. It was shown that morphogenetic patterns of calcium oxalate crystallization on apatite substrates under the action of Aspergillus niger micromycete are determined by the chemical properties of the crystallization medium, which depends on the solubility of the underlying substrate and on its chemical composition and structural features (dispersity and porosity). The main difference between oxalate crystallization under the influence of Aspergillus niger micromycete on the surface of apatite substrates and on the surface of calcite marble is the predominance of whewellite over weddellite on all stages of growth.

The study of the phase formation of phosphates in the solutions simulating the normal inorganic composition of human urine was carried out by the precipitation method. All calcium and magnesium phosphates typical for the kidney stones were synthesized: brushite, octacalcium phosphate, hydroxyapatite, struvite and Mg-whitlockite. The regularities of the calcium and magnesium phosphates formation in the crystallization medium of variable composition were found out. The borders of the crystallization areas of the synthesized phases were determined in the axes «initial pH value—main components’ concentration». In general, phosphates crystallization areas are defined by the starting concentrations of the main components, pH value of the crystallization medium and by the presence of the additional ions in the solution. It was shown that crystallization of any calcium phosphate leads to the significant decreasing of the pH value of the crystallization medium. Adding of the inorganic components typical for the human urine into the Ca–PO4 system leads to the moving of the crystallization area borders of the calcium phosphates (brushite, octacalcium phosphate, apatite). Crystallization doesn’t occur in the areas that are characterized by the composition and pH typical for the normal human urine. Increasing amount of the precursors or pH values leads to the start of the phosphate crystallization.

Chitosan is a biopolymer possessing extensive properties like biodegradability and biocompatibility due to which it has been extensively used for multifunctional applications. Among the various uses the biomedical applications of chitosan have produced results which has taken us a step closer towards the inhibition of various lethal diseases. In order to improve the activity of chitosan or to improve the drug loading efficiency, composites of chitosan with other polymers, noble metals, nanotubes, bioglass and various other moieties have been prepared. The current review, focusses on the application of chitosan and chitosan based nanocomposites for the delivery of drugs thereby throwing light on how chitosan based systems enable the sustained and prolonged release of drugs thus leading to the effective treatment of infections and diseases.

The mesostructural, phase compositional, photocatalytic and anti-fungicidal properties of sol-gel-derived TiO2- and epoxy-titanate coatings are investigated. The effect of epoxy-titanate coatings doped with titanium dioxide nanoparticles (TiO2 P25) and detonation nanodiamonds on inhibiting the growth and development of a number of mold micromycetes is discussed. Biomineralization phenomena in epoxy-titanate coatings that occur under the influence of a number of mold fungi are found.

Detailed crystal chemical characterization of human pathological cardiovascular deposits (PCD) was conducted applying wide set of the instrumental methods (XRD, FTIR, Raman, SEM, different chemical analyses). There was some progress achieved in the understanding of it formation mechanism. The obtained data evidence that pathological cardiovascular deposits are presented by non-stoichiometric water-bearing B-type carbonated hydroxyapatite just like other apatites of the human body. But PCD apatite is characterized by higher concentration of B-type carbonate ion (up to ~ 6 wt%) which leads to the increasing influence of the carbonate-ion on the unit cell parameters in comparison with water and other substitutes. Another difference between PCD apatite and other pathogenic apatites of the human body is the smaller variations of the unit cell parameters, caused by smaller variations of the blood chemical composition. It was shown that apatite on the surface of PCD is characterized by the more non-stoichiometric composition compared to apatite inside these deposits. It is assumed that the formation mechanisms of the PCD apatite and the bone apatite may be similar.

The effect of bacteria that present in the human urine (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus) was studied under the conditions of biomimetic synthesis. It was shown that the addition of bacteria significantly affects both the phase composition of the synthesized material and the position of crystallization boundaries of the resulting phosphate phases, which can shift toward more acidic (struvite, apatite) or toward more alkaline (brushite) conditions. Under conditions of oxalate mineralization, bacteria accelerate the nucleation of calcium oxalates by almost two times and also increase the amount of oxalate precipitates along with phosphates and stabilize the calcium oxalate dihydrate (weddellite). The multidirectional changes in the pH values of the solutions, which are the result of the interaction of all system components and the crystallization process, were analyzed. The obtained results are the scientific basis for understanding the mechanisms of bacterial involvement in stone formation within the human body and the creation of biotechnological methods that inhibit this process.

Crystals of Ga-rich, Fe-bearing tourmaline (∼25 wt% Ga2O3, 11 wt% FeOtotal) were grown from hydrothermal solution at 100 MPa and 600°C. The crystals were grown on a seed as a newly formed, up to 200 μm thick layer and, in addition, as free, spontaneously nucleated elongated prisms, 10 to 200 μm in size. The crystal structure of the synthetic tourmaline was studied by Mossbauer spectroscopy and single-crystal X-ray diffraction (to an R -index of 0.032; a = 16.000 (1), c = 7.257(1) A). Gallium and iron cations are distributed over the Y and Z octahedral sites according to the crystal-chemical formula (Na0.95□0.05) (Ga1.34Fe2+ 0.62Al0.44Fe3+ 0.34Ni0.26) (Al3.28Ga1.92 Fe2+ 0.41Fe3+0.39) (Si6O18) (BO3)3 (OH2.29O0.71) (O), suggesting that the disordered distribution previously shown for Al3+ also holds for other trivalent cations in tourmalines.

Present paper is devoted to the research of the calcification processes in the blood plasma of human body. Spontaneous crystallization from the solution modeling the inorganic part of the blood plasma has been carried out. Obtained precipitates were studied by the various instrumental methods (X-ray powder diffraction, Fourier-transformed infrared spectroscopy, scanning electron microscopy, electron probe microanalysis and gas-volumetric method). All gathered data allow to summarize that nonstoichiometric carbonated hydroxyapatite with low crystallinity (CSD lengths 18–28 nm), high water content and small amount of chlorine ion was obtained throughout the syntheses. Part of vacancies at the Ca sites varies from 0.17 to 0.87; the value of the Cat/(P + C) ratio—from 1.52 to 1.64 (where Cat = Ca 2+ + Na + + K + + Mg 2+ ). The poor crystallized synthetic apatites with high carbonate ion content (from 4.34 to 5.54 wt%) and c parameter (6.888–6.894 A) are analogues of the apatites of the pathological cardiovascular deposits. They can be obtained from the solution modeling human blood plasma by the inorganic components with calcium phosphate supersaturation 25 and 50 and with 10 and 12 weeks experiment time.

The results of the multi-year monitoring of the state of Saint Petersburg stone monuments are summarized. The unique collection of decorative stones in museum Necropolis and the deposits that were most likely used to create them are studied. The processes of stone monuments’ degradation in response to physical, chemical and biogenic influences are discussed. Special attention is paid to describing the monitoring methodology and the structure of the monitoring information database. Drawing on received results, the strategy for the conservation and restoration of monuments are discussed. The obtained data are of exceptional scientific interest in studying the processes of stone deterioration under the impact of the environment.

The presence and study of the species composition of bacterial and fungal colonies in renal stones was determined. It was shown that the presence of microorganisms depends on the phase composition of the renal stone. No microbial colonies were detected in oxalate stones. Under the action of the acid-producing bacterial and fungal colonies, secondary crystallization of calcium oxalates (whewellite and weddellite) on phosphate aggregates can occur.

Methods and approaches to be used in monitoring the monument condition are discussed. The main stages of materials science expert analysis are considered. The technique for qualimetric assessment of the integrated condition of the material and various options of mapping the forms of its deterioration are described: those based on the results of visual inspection, ultrasonic sounding, and also using computer technologies, including 3D laser scanning. The potential and efficiency of comprehensive laboratory instrumental methods for studying the material of the monument and the products of its deterioration are analyzed: polarization microscopy, X-ray powder diffraction, scanning electron microscopy, electron microprobe analysis, IR spectroscopy. The design of the database on the state of sculptural monuments in St. Petersburg, for the storage, analysis and structuring of the material gathered during the monitoring, is presented.

Based on the results of many years of monitoring, the unique stone material of tombstones in the historical Necropoleis of the Museum of City Sculpture is described, represented by marbles, limestones, granites and other rocks. The most probable locations of deposits of the used decorative facing stone were in most cases identified with the help of archival data and other literature. It is shown that the diversity of stone in the Necropoleis is as great as in downtown St. Petersburg. There are also unique monuments (to N.A. Rimsky Korsakov, I.R. Tarkhanov, etc.), whose stone material has not yet been found elsewhere. The stone was delivered mainly from Italy and the vicinity of St. Petersburg (from the territories of the present Leningrad region, Karelia and Finland).

The history and temporary changes in the condition of outstanding artistic monuments in the museum Necropoleis, made of various materials, are surveyed: those to A.I. Kosikovsky (Paolo Catozzi and A.I. Terebenev, sculptors, 1840), E.A. and V.N. Kochubey (A. Costoli, sculptor, 1856), A.Ya. Okhotnikov (F. Thibaut, sculptor, 1800s), M.V. Lomonosov (J. Stalin, author of the design, 1766), V.V. Stasov (I.Ya. Ginzburg, sculptor, I.P. Ropet, architect, 1908), P.V. Kindyakov (Paolo Catozzi, sculptor, 1828), N.M. Karamzin (of unknown authorship, 1820s) and E.A. and E.N. Karamzin (of unknown authorship, 1850s), A.Ya. Potemkina (of unknown authorship, 1830s). The materials of the monuments are described, the results of restoration work and dated materials science analyses are given.

The processes of stone and bronze destruction of the monuments in the Necropoleis were studied as a result of the monitoring. All forms of stone weathering, (mechanical damages, deposits, stone loss) are examined, their classification is proposed, the frequency of occurrence on various rock types is assessed. Particular attention is paid to biodegradation of the stone under the influence of microorganisms (bacteria, fungi, lichens and algae), formation of gypsum-rich patina on the surface of carbonate rocks and patina on the surface of bronze monuments.

A study of the ambient air, soil, vegetation, and biogenic layers on the surface of the monuments was carried out in order to identify environmental factors that have an adverse effect on the condition of the monuments in the Museum necropoleis. It was found out that the corrosivity of the air at the Necropoleis corresponds to the medium category C3 and gradually decreases (primarily due to a reduction in the sulfur dioxide content). The soil near the monuments is another source of contamination of their surface, occurring with the participation of various microorganisms. Selective accumulation of miscellaneous elements on the surface of monuments from the environment and low-molecular organic substances depends, above all, on the species composition of the lithobiont community. The presence of woody plants produces microclimate effects in different parts of the Necropoleis, which has a significant impact on the condition of the monuments.

The experience of the Museum of Urban Sculpture in chemical protection of stone monuments from biodeterioration is discussed. The effectiveness of various chemical biocides was compared. High efficiency of the three-stage treatment of monuments using a combination of different compounds in comparison with the known methods is shown. The effectiveness of the used protective compounds was assessed by the speed of the reinstatement of the microbial community over several years after the treatment of the monument. The potential of laser technologies for the restoration of monuments was proven experimentally. It is shown that the effectiveness of laser removal of biofilms from the stone surface is comparable, and in some cases even exceeds that of chemical treatment. In the case of intensive development of mosses and lichens on the surface of monuments, the effectiveness of laser cleaning significantly exceeds that of chemical biocides. Laser cleaning to remove gypsum-rich patina is also effective, but does not always result in the complete removal of gypsum crystals.

The crystallization of calcium oxalates (weddellite and whewellite) by interaction of calcite marble with fungus Aspergillus niger , one of the most active stone destructors, was studied under in vitro conditions. The temporal development of acid production of fungus as well as the sequence of formation and morphogenesis of the growing oxalate hydrates crystals were investigated in detail. Furthermore, the relationships between morphology and growth conditions of crystals within the biofilms on the surface of carbonate rocks are discussed.

The crystal structure of synthetic Ni-rich tourmaline with a nickel content of 18.96 wt.% NiO (a = 15.890(2), c = 7.1815(8) Å) has been refined to R = 3.1% using single-crystal X-ray diffraction data. It has been shown that Ni is distributed not only over the Y, but also over the Z sites according to the ideal formula Na(Ni22+Al)(Al5Ni2+)(Si6O18)(BO3)3(OH)4. Based on bond valences and charge balance analysis it has been shown that this composition corresponds to the stable disordered member of the solid solution series NaAl3Al6(Si6O18)(BO3)3(O)3(OH) NaNi32+Al6(Si6O18)(BO3)3(OH)4.Taking into consideration available structural data on Me2+ (Ni, Cu, Co, Fe, Mn)-rich tourmalines, cation-size mismatch and bond-valence calculations we assume that there are no structural constraints precluding occurrence of these cations in both octahedral sites. Divalent transitional metal-rich tourmalines have not been found in Nature probably due to the insufficient concentration of these elements in B-rich geological systems.

The study of the influence of carbonate ions in a solution to Sr-distribution in system «solution–crystal» and to ion substitutions and the non-stoichiometry of formed CaHA–SrHA solid solutions was carried out. The CaHA–SrHA solid solutions were synthesized by precipitation from aqueous solutions with the atomic C / P ratio equal to 0, 0.05 and 0.1 at T = 90 °C. Resulting precipitates were studied using various methods including X-ray powder diffraction, infrared spectroscopy and different chemical analyses. The results of the study have shown that in the range of values of (Ca + Sr)/P in the water solution from 40% to 85%, the presence of carbonate ions ( C / P = 0.05–0.1) promotes the incorporation of strontium in the apatite. Crystalline apatite solid solutions formed from water solutions of such composition are more defective compared to apatites that are mainly calcium or strontium. They are characterized by a smaller size coherence scattering domain length along [0 0 1] direction and a greater number of carbonate ions, water molecules and vacancies at the Ca-sites.