Polished samples of Chernobyl "lava" and rich variety of trapped inclusions were studied using complementary spectroscopic methods and by electron microscopy. Spectroscopic properties of the brown "lava" variety in infra-red and visible range are dominated by contribution of nearly stoichiometric (U,Zr)O2+x (x <= 0.05-0.1). At the same time, abundant inclusions of strongly hyperstoichiometric urania are detected using electron microscopy. Their morphology, internal structure (when present) and textural relationships with other included phases indicates partial oxidation of fuel from degraded bundles. Melting and/or liquefaction of hyperstoichiometric urania occur at much lower temperatures than for ideal UO2, explaining "molten" appearance of many inclusions. Fuel-cladding interaction prior to the explosion led to formation of monoclinic and tetragonal polymorphs of ZrO2 with markedly different crystalline quality; the high temperature modifications are stabilized by uranium admixture. These phases were formed on the saturation stage of the interaction. At later stages of the accident, uranium-rich zircon crystals were formed as a result of reaction of the zirconia-based pieces with molten construction materials. Dynamic conditions in the melt pool explain remarkably complex internal structure of some zircon crystals: some of them experienced several growth-dissolution-regrowth events with clear compositional differences between the "growth"-related and "secondary" generations. Partitioning of Nb and Si between droplets of former steel and the surrounding melt allowed estimation of oxygen fugacity in the pool. Strongly reducing conditions down to IW-3.6, where IW - iron-wustite buffer, were present. Implications for the accident scenario are presented.

Tetradentate phenanthroline-based ligands have demonstrated ability to efficiently extract uranium(VI) from nitric acid solutions. While their coordination with U(VI) has been extensively studied, their behavior toward tetravalent actinides under conditions relevant to spent nuclear fuel reprocessing remains poorly understood. Here, we investigated the extraction and coordination chemistry of Th(IV) in the presence of excess U(VI). Using a combination of solvent extraction, UV-Vis and Raman, we demonstrated that when the organic phase is pre-loaded with the uranyl ion pair [UO2L(NO3)]+[UO2(NO3)3]-, Th(IV) undergoes a selective anion-exchange reaction with the trinitratouranyl anion, forming the mixed ion pair [UO2L(NO3)]+[Th(H2O)2(NO3)5]-. Single-crystal X-ray diffraction further confirms the formation of heterometallic U-Th complexes, including ([UO2L(NO3)]+)2[Th(NO3)6]2-, providing direct structural evidence for mixed-metal ion pairing. These results revealed a previously unrecognized mechanism of Th(IV) uptake driven by anion exchange rather than direct ligand coordination.

The synthesis, structure, and properties of the first anionic bimetallic NpCs MOF are reported. The structure of the obtained compound is based on a novel type of secondary building unit (SBU) - a Np4Cs2O8 cluster. The SBU contains a set of cation-cation interactions: NpO⋯Np, Np⋯Cs, and Cs⋯Cs. The micropores of the new material were found to be too small to facilitate the sorption and ion exchange of 137Cs. The limiting pore size of the framework is 2.69 Å. The synthesized material is stable up to 400 °C, stable during hydrolysis and does not deteriorate at doses of at least 6 MGy. The NpCs MOF may be of interest for the separation of gases with small atom sizes, such as hydrogen isotopes and light noble gases.

New nanodispersions of silver particles stabilized by oligomeric chitosans have been synthesized. The synthesis was controlled by electronic absorption spectroscopy and the particle size (from 30 to 90 nm) was measured by dynamic light scattering. The formation of ring-shaped deposits on glass slides from these dispersions was studied. It was proposed to use the obtained nanodispersions and ring-shaped deposits based on them as substrates for Raman spectroscopy. A specific modification of the synthesis protocol of the nanodispersions was carried out in order to obtain larger nanoparticles (90 nm) with a small thickness (2-5 nm) of the oligochitosan shell, which does not limit the measurement of the signal of small amounts of analytes. It is shown that SERS substrates based on modified nanodispersions allow obtaining a well resolved Raman spectrum of an analyte (Rhodamine 6 G) deposited on the substrate at a low concentration (10- 8 M). Thus, the developed solid SERS substrates can be used for the analysis of trace amounts of chemicals in analytical applications.

ZnO/CNT nanocomposites with CNT content from 0.01 to 10 wt

In this work, stabilized f-ZrO2 ceramic samples with the compositions of (Zr0.82Y0.09Eu0.09)O1.91, (Zr0.82Y0.09Tb0.09)O1.91 and (Zr0.82Y0.09Eu0.045Tb0.045)O1.91 were studied. The elemental composition was studied by electron probe microanalysis, and the luminescent properties were studied by local cathodoluminescence (CL). An analysis of the Eu3+ CL spectra confirmed the stabilization of the cubic phase in ceramics at room temperature. The study of the obtained CL spectra, the 5D4-7F5Tb3+ band luminescence decay kinetics, CL images and excitation spectra showed europium sensitization by terbium in (Zr0.82Y0.09Eu0.045Tb0.045)O1.91. Keywords: f-ZrO2, Eu3+, Tb3+, Ceramics, Sensitization, Cathodoluminescence

One-stage synthesis technology for preparing carbon adsorbents with tailored porosity from agricultural waste is worthwhile due to their extensive application value. Thermal gravimetric analysis, low-temperature N2 adsorption, X-ray diffraction (XRD), small-angle X-ray scattering (SAXS), and Raman spectroscopy were used to record the structure transformations of carbon materials, namely pore development, proceeding in the course of the step-wise pyrolysis of renewable and low-cost raw materials such as walnut shells (WNSs), which was carried out within a temperature range of 240–950 °C in a CO2 flow. The minimum threshold carbonization temperature for preparing nanoporous carbon materials from WNSs, determined by the examination of the N2 adsorption data, was 500 °C. The maximum specific micropore volume and BET surface achieved in the process without holding a material at a specified temperature were only 0.19 cm3/g and 440 m2/g, respectively. The pyrolysis at 400–600 °C produced amorphous sp2 carbon. At a temperature as high as 750 °C, an increase in the X-ray reflection intensity indicated the ordering of graphite-like crystallites. At high burn-off degrees, the size of coherently scattering domains becomes smaller, and an increased background in X-ray patterns indicates the destruction of cellulose nanofibrils, the disordering of graphene stacks, and an increase in the amount of disordered carbon. At this stage, pores develop in the crystallites. They are tentatively assigned to crystallites with sizes of 15–20 nm and to micropores. According to the Raman spectra combined with the XRD and SAXS data, the structure of all the pyrolysis products is influenced by the complex structure of the walnut shell precursor, which comprises cellulose nanofibrils embedded in lignin. This structure was preserved in the initial stage of pyrolysis, and the graphitization of cellulose fibrils and lignin proceeds at different rates. Most of the pores accessible for gas molecules in the resulting carbon materials are associated with former cellulose fibrils.

A novel phthalocyanine-based hybrid nanofilm is for the first time successfully applied as an oxidative platform for surface enhanced Raman spectroscopy (SERS) sensing to fine-resolve Raman-inactive compounds. The hybrid is formed by self-assembly of zinc(II) 2,3,9,10,16,17,23,24-Octa[(3 ',5 '-dicarboxy)-phenoxy]phthalocyaninate (ZnPc*) with the solid-supported monolayer of graphene oxide (GO) mediated by zinc acetate metal cluster. Atomic force microscopy, UV-vis and fluorescence spectroscopies confirm that this simple coordination motive in combination with molecular structure of ZnPc* prevents contact quenching of the light-excited triplet state through aromatic stacking with GO particles. Fluorescence probing with Sensor Green and terephthalic acid as specific indicators of active oxygen intermediates shows that the hybrid nanofilm initiates selective singlet oxygen generation under visible light. Direct one-electron oxidation of tetramethylbenzidine (TMB) (1.0x10-7 m) on the hybrid surface in the presence of 100 nm silver nanoparticles as plasmonic hot-spots under 450-640-nm light irradiation yields well-resolved resonance Raman spectrum of the oxidized form TMB+1. Using these hybrid nanofilms as visible light platforms for redox reaction of target analytes without additional oxidizing agents, the range of Raman-detectable compounds can be significantly expanded through a rapid ultrasensitive SERS screening of substances currently considered Raman-inactive.

This work reports on the possibility of producing oxide InGaMgO4 by two-stage heat treatment of glycine-, starch- and PVA-nitrate precursors. The products formed as a result of their heating at low temperatures (≈ 90°С) were studied by powder X-ray diffraction. It was found that the powder formed from the glycine-nitrate precursor contains nanocrystalline In2O3, and drying of the polymer-nitrate compositions leads to the production of a thermally stable X-ray amorphous product. Its annealing at temperatures above 800°C allows synthesizing powder InGaMgO4 free of impurity phases. High-temperature treatment of the powder formed from the glycine-nitrate precursor also leads to the production of InGaMgO4, but does not remove the In2O3 impurity. Using scanning electron microscopy, it was found that single-phase InGaMgO4 powders synthesized from polymer-nitrate precursors have a similar grain structure but differ in grain size distribution. Presumably, this difference is due to the structural features of starch and PVA macromolecules used for the preparation of precursors. Oxide InGaMgO4 was characterized using differential scanning calorimetry, Raman and diffuse reflectance spectroscopy. The value of its band gap energy Eg was determined using the Tauc method.

Nanocrystalline TiO2 nanotube electrodes were fabricated by electrochemically anodizing the titanium in the electrolyte with an ethylene glycol with addition of 0.5

A comparison was made of the physicochemical and physicomechanical properties of films and coatings based on latex polyacrylates before and after their modification water-soluble tetrasodium salt of copper–phthalocyanine–tetrasulfonic acid. Using atomic-force microscopy methods, Raman spectroscopy and thermogravimetry showed that phthalocyanine is localized on the surface of latex particles in the interparticle regions of films and coatings due to interaction between phthalocyanine and polyacrylate. Using the method of dynamic mechanical relaxation spectroscopy, an increase in the intensity of α-relaxation was established upon modification of polymer films as a result of disruption of the relaxation homogeneity of the polymer material. Adhesion of unmodified and modified polymers to a metal substrate causes a decrease in the intensity of α-relaxation and frequency of the oscillatory process. Modification of the polymer and its adhesion to the substrate are accompanied by a decrease in its elasticity.

KPuO2CO3 solid phase precipitation from hexavalent plutonium solution: structure and stability area.

The electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT) was performed in the presence of a water-soluble anionic copper and zinc octa(3′,5′-dicarboxyphenoxy)phthalocyaninate containing 16 ionogenic carboxylate groups. The influences of the central metal atom in the phthalocyaninate and EDOT-to-carboxylate group ratio (1:2, 1:4, and 1:6) on the course of electropolymerization were studied using electrochemical methods. It has been shown that the polymerization of EDOT in the presence of phthalocyaninates proceeds at a higher rate compared to that in the presence of a low-molecular-weight electrolyte (sodium acetate). Studies of the electronic and chemical structure using UV–Vis–NIR and Raman spectroscopies showed that the use of copper phthalocyaninate leads to a higher content of the latter in PEDOT composite films. The 1:2 EDOT-to-carboxylate group ratio was found to be optimal for a higher content of phthalocyaninate in the composite film.

The balance of CO2 during abundant basaltic magma production is an important factor of volcanic hazards and climate. In particular, this can be explored based on CO2-rich mantle-derived magmas or carbonate assimilation by basaltic melts. To reconstruct the origin of Fe-rich carbonates hosted by Cenozoic basalts from Wangtian’e volcano (northeast China), we studied elemental compositions of melt, crystalline and fluid inclusions in magmatic minerals as well as the oxygen and carbon isotope compositions of the plagioclase and carbonates from basalts. The crystallization of basaltic magmas occurred in shallow chamber (∼4 km) at temperatures of 1,180°C–1,200°C and a pressure of 0.1 ± 0.01 GPa. Stable Fe-rich carbonates occur in the Wangtian’e tholeiite basalts as groundmass minerals, crystalline inclusions in plagioclase and globules in melt inclusions, which suggests that they crystallized from a ferrocarbonate melt. The values of δ18О and δ13С in the minerals analyzed by laser fluorination method are in line with the sedimentary source of Fe-rich carbonates, indicating assimilation and partial decomposition of carbonate phases. The parent ferrocarbonate melt could be produced during interactions between the basaltic magma and the crustal marbles. The phase diagram and thermodynamic calculations show that the ferrocarbonate melt is stable at a temperature of 1,200°C and a pressure of 0.1 GPa. Our thermodynamic calculations show that carbonate melt containing 73 wt% FeCO3, 24 wt% MgCO3 and 3 wt% CaCO3 is in thermodynamic equilibrium with silicate melt in agreement with our natural observations. The proposed mechanism is crustal carbonate sediment assimilation by the intraplate basaltic magma resulting in the melt immiscibility, production of the ferrocarbonate melt and the following Fe-rich carbonate mineral crystallization during magma residence and cooling.

Unique carbonization behavior of 1-fluoroadamantane was revealed at pressures 5.5-9 GPa and temperatures up to 1300 degrees C. In course of the carbonization, formation of nanodiamonds was detected at record low temperature of 420 degrees C and pressure of 5.5 GPa. Analysis of sample mass decrease implies that for the samples synthesized at temperatures up to 600-800 degrees C the decomposition reaction proceeds with release of molecular hydrogen, and for those synthesized at higher temperatures with formation of volatile hydrocarbons. At 8-9 GPa, sustained growth of nanodiamonds is observed over whole temperature range studied, while at 5.5 GPa, graphitic sp2 carbon is formed along with nanodiamonds at temperatures above 600 degrees C. It is suggested that the molecular hydrogen formation regime of carbonization is critically important for nanodiamond nucleation. Subsequent growth of nanodiamonds is determined by the pressure-dependent catalytic activity of the C-H-F growth medium. Trans-port properties measured on the 5 nm-nanodiamonds demonstrate p-type semiconductor behavior with activa-tion energy of 0.1 eV at room temperature and unusual non-monotonic pressure dependence of conductivity. Transmission electron microscopy reveals surface-bound sp2-C domains on nanograins; vibrational spectroscopy indicates strong surface hydrogenation of synthesized nanodiamonds. Modeling confirms plausibility for for-mation of metastable surface with reconstructed sp2 and hydrogenated fragments allowing for surface conduc-tivity. Facile synthesis of nanodiamonds from 1-fluoroadamantane can be of great interest for fundamental investigations and practical applications. Our experiments suggest that fluorine-containing fluids may play a significant role in genesis of natural diamond.

Functionally different 2D hybrids were assembled by using the same starting set of components comprising graphene oxide, perylene chromophore, polydiacetylene surfactant and divalent ions to modulate the properties of resulting systems.

Ballas is a rare polycrystalline diamond variety characterized by a radially oriented internal structure and spheroidal outer shape. The origin of natural ballases remains poorly constrained. We present the results of a comprehensive investigation of two classic ballas diamonds from Brazil. External morphology was studied using SEM, high-resolution 3D optical microscopy, and X-ray tomography. Point and extended defects were examined on polished central plates using infra-red, photo- and cathodoluminescence spectroscopies, and electron back-scattering diffraction; information about nanosized inclusions was inferred from Transmission Electron Microscopy. The results suggest that fibrous diamond crystallites comprising ballas are split with pronounced rotation, causing concentric zoning of the samples. Pervasive feather-like luminescing structural features envelop single crystalline domains and most likely represent fibers with non-crystallographic branching. These features are enriched in N3 point defects. Twinning is not common. The nitrogen content of the studied samples reaches 700 at.ppm; its concentration gradually increases from the center to the rim. Annealing of the ballases took place at relatively high temperatures of 1125–1250 °C; the annealing continued even when the samples were fully grown, as suggested by the presence of the H4 nitrogen-related defects in the outer rim. Presumably, the ballas diamond variety was formed at high supersaturation but in conditions favoring a small growth kinetic coefficient. The carbon isotopic composition of the studied ballases (δ13C = −5.42, −7.11‰) belongs to the main mode of mantle-derived diamonds.

In this article, we report to the best of our knowledge the first modification of NPs with ligands for combined radiopharmaceuticals. Nanoparticles with suitable magnetic properties can be used both for diagnostics as a contrast for MRI and for therapy, including the insufficiently studied magneto-mechanical therapy. Strontium hexaferrite is one of the few hard-magnetic materials for which stable biocompatible colloidal solutions can be obtained. Strontium hexaferrite nanoparticles coated with silicon dioxide (SHF@SiO2) were modified with an amino silane coupling agent (3-aminopropyl)triethoxysilane and azacrown ether derivatives with six heteroatoms in rings were covalently linked to the amine group through the carboxyl group. The hard magnetic nanoparticles were then radiolabeled with 207Bi with a labelling yield of up to 99.8%. In vitro experiments showed that the complex SHF@SiO2-APTES-L2-207Bi is stable enough to be a potential theranostic radiopharmaceutical.

A noncovalent integration of nanosheets of molybdenum disulfide (MoS2) and the zinc porphyrin complex Zn(II) 5,10,15,20-tetrakis(4-carboxyphenyl)porphine (ZnTCPP) through coordination bonding with metal clusters of zinc acetate (Zn[OAc](2)) was applied for synthesis of stable hybrid nanomaterial avoiding surface prefunctionalization. The X-ray powder diffraction in combination with the BET nitrogen adsorption method confirms formation of a ZnTCPP-based surface-attached metal-organic framework (SURMOF) with micropores of 1.63 nm on the MoS2 nanosheets. Fluorescence spectroscopy confirmed Forster resonance energy transfer (FRET) between MoS2 and ZnTCPP without contact quenching. Fluorescent trapping with terephthalic acid for hydroxyl radicals and Sensor Green for singlet oxygen was applied for studying the pathways of photodegradation of model organic pollutant 1,5-dihydroxynaphthalene (DHN) in the presence of SURMOF/MoS2. Visible light initiates sensitization through the excitation of ZnTCPP generating singlet oxygen, whereas UV-light promotes either aerobic FRET-mediated "Z scheme" or anaerobic "Type II heterojunction" mechanisms. Owing to its multimodal photochemistry, the SURMOF/MoS2 hybrid showed comparatively high photocatalytic activity in UV-assisted degradation of DHN (k(eff)(UV) = 4.0 x 10(-2) min(-1)) as well as the antibacterial activity confirmed by E. coli survival test under visible light. Noncovalent self-assembly utilizing coordination bonding in SURMOFs as supramolecular adhesive to avoid surface premodification provides a basis for new types of multicomponent nanosystems with switchable functionalities by combining different 2D materials and chromophores in one hybrid structure.

The possibility of stabilization of zinc(II) 2,3,9,10,16,17,23,24-octa[(3,5-sodium biscarboxylate)phenoxy] phthalocyaninate (ZnPc 16 ) by its hybridization with the surface of graphene oxide (GO) sheets via van der Waals or coordination bonds with functional groups of the carbon matrix in the GO hydrosols has been investigated. A combination of physicochemical analysis methods (scanning electron microscopy, fluorescence microscopy, powder X-ray diffraction, and Raman spectroscopy) has been employed to confirm the integration of ZnPc 16 with GO nanosheets and to study the morphology and structure of the obtained hybrid materials. Using electronic absorption spectroscopy, it has been found that, regardless of the hybridization method, the binding of the macrocycles to the inorganic particles increases the stability of ZnPc 16 in an aqueous medium being irradiated with visible light. The analysis of spectral kinetic data has shown that, in contrast to the system obtained by direct integration of ZnPc 16 and GO, the hybrid material formed by coordination bonding of the components via zinc acetate (Zn(OAc) 2 ) as a binding metal cluster is able to exhibit photocatalytic properties in oxidative photodegradation of some model organic pollutant substrates (rhodamine 6G, 1,5-dihydroxynaphthalene, and 1,4-nitrophenol). The proposed colloid-chemical approach to the stabilization of photoactive water-soluble phthalocyaninates makes it possible to increase their resistance to photoinduced self-oxidation and can be adapted for various derivatives of tetrapyrrole compounds possessing photosensitizing properties.