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Materials with high thermo mechanical properties are required as laser media for high-powered lasers. One of such materials is lutetium-aluminum garnet (LuAG) doped with ytterbium. In the present work, we discuss for the first time a full comparative study of 5% Yb-doped LuYAG ceramics with variation Lu/Y ratio. Samples were prepared with addition of B2O3, MgO and SiO2 which were used as sintering aids. Grain sizes, shrinkage curves, lattice constants and transmission spectra were measured for all samples. Thermal conductivity was measured in a wide temperature range for all studied samples. Output power of 12 W and 60% slope efficiency were obtained on the 5% Yb:LuAG disk laser.

The main objective of this work is to apply Large Eddy Simulation (LES) on hydrogen subsonic round jets in order to evaluate modelling strategies and to provide guidelines for similar applications. The ADREA-HF code and the experiments conducted by Sandia National Laboratories are used for that purpose. These experiments are very suitable for LES studies because turbulent fluctuations have been measured which is something rare in hydrogen experiments. Hydrogen is released vertically from a small orifice of 1.91 mm diameter into stagnant environment. Three experimental cases are simulated with different Reynolds number at the release area, namely 885, 1360 and 2384. Hydrogen mass fraction and velocity mean values and fluctuations are compared against the experimental data. Several grid resolutions are used to assess the effect on the results, using mainly the Smagorinsky subgrid scale model. In the lowest Reynolds number case, an Implicit LES code, used independently from a different scientific group, is also tested. In this case, the performance of the RNG-LES subgrid scale model of the ADREA-HF code is also examined. Additionally, the effect of Smagorinsky constant and of the Van Driest correction is evaluated. The amount of the resolved turbulence and of the velocity spectra are presented. Finally, the effect of the release modelling is discussed. The analysis shows that even a coarse discretization of the release area can give acceptable results for hydrogen safety engineering applications. However, dense grids are required for the more accurate prediction of the turbulent characteristics. The two LES codes gave similar results and the overall agreement with the experiment was satisfactory.

Due to its unique supramolecular structure, cellulose is widely used as a template agent, ensuring an easy structuring of anatase TiO2 particles with subsequent release after the organics burning. This work is devoted to the synthesis of microcrystalline cellulose-TiO2 (MCC-TiO2) composite photocatalyst by preserving the intermediate organic–inorganic structures. A series of the MCC-TiO2 materials were prepared via solvothermal sol–gel method in n-decane and caproic acid solvents and characterized by X-ray diffraction, transmission electron microscopy, IR spectroscopy, 1H NMR and TG/DSC methods. The photocatalytic activity of the prepared materials was evaluated by the decomposition of formic acid in aqueous solutions. The composites failed to be formed in n-decane, while in caproic acid, acting as solvent and reagent, anatase TiO2 nanoparticles were formed onto the crystalline domains of cellulose, tightly fixed due to covalent Ti–O–C bonds. The materials formed in caproic acid showed a higher photocatalytic activity, explained by a complementarity of the organic and inorganic components. The specific activity (normalized on TiO2 mass) of best synthetized composite materials was almost twice higher than that of Aeroxide P25 TiO2 reference photocatalyst.

The influence of deformation and heat treatment on the mechanical properties of rebar steel is investigated on a pilot system. Specifically, with intermittent quenching and subsequent self-tempering, the intense-cooling time determines the tempering temperature of the quenched steel and hence the final mechanical properties of the rebar. The influence of the water pressure in the intense-cooling chamber on the uniformity of the mechanical properties is studied for steel with 0.31, 0.32, and 0.35% C; the water pressure is varied from 0.2 to 0.6 MPa. On that basis, it is established that the water pressure in the cooling chamber must be no less than 0.3 MPa, and the carbon content in the steel must be more than 0.32% in order to ensure that the mechanical properties of the rebar steel conform to the AT500 strength class according to State Standard GOST 10884–2004.

The mathematical models implemented in the CABARET-SC1 code are described and the code validation results characterizing its potential in the description of key processes influencing hydrogen propagation in the reactor containment in the course of a severe accident are presented. Agreement with experimental data was achieved by refining the computational grids and adding a radiative heat-transfer model with no adjustable parameters or semi-empirical models.

This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. Support from Estonian Research Council grant PUT PRG 619 is gratefully acknowledged. The multi-anvil experiments at LMV were supported by the French Government Laboratory of Excellence initiative no ANR-10-LABX-0006, the Région Auvergne and the European Regional Development Fund (ClerVolc Contribution Number 478)., Electronic band structure in germanium nitride having spinel structure, γ-Ge3N4, was examined using two spectroscopic techniques, cathodoluminescence and synchrotron-based photoluminescence. The sample purity was confirmed by x-ray diffraction and Raman analyses. The spectroscopic measurements provided first experimental evidence of a large free exciton binding energy De≈0.30 eV and direct interband transitions in this material. The band gap energy Eg = 3.65 ± 0.05 eV measured with a higher precision was in agreement with that previously obtained via XES/XANES method. The screened hybrid functional Heyd–Scuseria–Ernzerhof (HSE06) calculations of the electronic structure supported the experimental results. Based on the experimental data and theoretical calculations, the limiting efficiency of the excitation conversion to light was estimated and compared with that of w-GaN, which is the basic material of commercial light emitting diodes. The high conversion efficiency, very high hardness and rigidity combined with a thermal stability in air up to ~ 700 °C reveal the potential of γ-Ge3N4 for robust and efficient photonic emitters. © 2021, The Korean Institute of Metals and Materials. Published under the CC BY license., Euratom research and training programme 2014-2018 633053; Eesti Teadusagentuur ANR-10-LABX-0006, PUT PRG 619; ERDF; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART2.

Volatile organic compounds (VOCs) have a negative effect on both humans and the environment, therefore, it is crucial to minimize their emission. The conventional solution is the catalytic oxidation of VOCs by air, however, in some cases this method requires relatively high temperatures. Thus, the oxidation of short-chain alkanes, which demonstrate the lowest reactivity among VOCs, starts at 250–350 °C. This research deals with the ozone catalytic oxidation (OZCO) of alkanes at temperatures as low as 25–200 °C using an alumina-supported manganese oxide catalyst. Our data demonstrate that oxidation can be significantly accelerated in the presence of a small amount of O3. In particular, it was found that n-C4H10 can be readily oxidized by an air/O3 mixture over the Mn/Al2O3 catalyst at temperatures as low as 25 °C. According to the characterization data (SEM-EDX, XRD, H2-TPR, and XPS) the superior catalytic performance of the Mn/Al2O3 catalyst in OZCO stems from a high concentration of Mn2O3 species and oxygen vacancies.

The mixed vanadium-titanium oxo-alkoxy (VTOA) nanoparticles were synthesized via sol-gel method in a chemical reactor with ultra-rapid micromixing. The nucleation and growth kinetics and particles size, followed by the static/dynamic light scattering methods, were quite different from those of pure oxo-alkoxy titanium (TOA) and vanadium (VOA) species. It was shown that the TOA species appear first and serve to be centres of attraction for hydrolysed VOA species at the nucleation stage. However, at the vanadium content above 20 mol% large VOA species imprison sub-nucleus TOA species prohibiting the nucleus appearance. The model analysis of the VTOA induction kinetics validated a significant increase of the nucleus size with an increase of the precursor concentration. The results support a new paradigm of the sol-gel process describing profound restructuring of the oxometallic species during assembling at the nucleation stage.

Main properties of ytterbium doped lutetiumyttrium aluminum garnet ceramics with different ratios of lutetium to yttrium substitution (x=0-1) and different levels of ytterbium doping (5-15%) are investigated.

V-TiO2 photocatalyst with 0 ≤ V ≤ 20 mol% was prepared via the sol–gel method based on mixed oxide titanium–vanadium nanoparticles with size and composition control. The mixed oxide vanadium–titanium oxo-alkoxy nanonoparticles were generated in a chemical micromixing reactor, coated on glass beads via liquid colloid deposition method and underwent to an appropriate thermal treatment forming crystallized nanocoatings. X-ray diffraction, Raman, thermogravimetric and differential thermal analyses confirmed anatase crystalline structure at vanadium content ≤ 10 mol%, with the cell parameters identical to those of pure TiO2. At a higher vanadium content of ~20 mol%, the material segregation began and orthorhombic phase of V2O5 appeared. The crystallization onset temperature of V-TiO2 smoothly changed with an increase in vanadium content. The best photocatalytic performance towards methylene blue decomposition in aqueous solutions under UVA and visible light illuminations was observed in V-TiO2 nanocoatings with, respectively, 2 mol% and 10 mol% vanadium.

Intensive use of nanoparticles on an industrial scale leads to an increase in their content in the environment. This increases the risks of nano-sized objects entering the technological chains of the processing industries of the agro-industrial complex, in particular, brewing. The paper presents the results of the studies of the effect of nickel oxide nanoparticles used in various industries on the activity of the proteolytic type of enzyme preparation Neutrase 1.5MG, as well as on the results of laboratory mashing of light barley malt. The effect of different concentrations of NiO nanoparticles on the accumulation of low molecular weight nitrogenous substances during gelatin hydrolysis in model media was determined. It was found that if the content of nanoparticles exceeds 0.25 mg/cm3, the proteolytic capacity of the enzyme preparation is reduced up to 70% compared to the control at the concentration of nickel oxide nanopreparation of 2.0 mg/cm3. The experiments showed that an increase in the duration of contact between nanoparticles and proteases of the enzyme preparation in the reaction medium did not lead to an increase in the inhibitory effect of the nano-sized NiO. The laboratory mashing revealed more pronounced negative effect of nickel oxide nanoparticles on the accumulation of low-molecular nitrogen compounds. It is determined that in the presence of NiO nanopreparation, the hydrolysis efficiency of the starchy components of light barley malt is reduced. As a result, according to a number of indicators (concentration of amine nitrogen, reducing substances), the first wort obtained by mashing in the presence of nickel oxide nanoparticles at both lower (0.25 mg/cm3) and higher (2.0 mg/cm3) concentrations is inferior to samples obtained in the absence of nano-sized particles. Based on the above data, it is concluded that the presence of NiO nanoparticles in brewing environments is undesirable.

Chemical reactors with micromixing of liquids play an important role in the chemical engineering process leading to new materials with an improved functional response. We show that the liquids injection conditions correspondent to low Damkohler numbers may turn from the common liquid phase to unusual biphasic liquid/vapour fluid flow due to the cavitation phenomenon. We propose in-situ physical measurements of the cavitation threshold in the exocentric T-mixer using light scattering method. Numerical calculations support the assignment to cavitation and show its critical relation to the T-mixer geometry.

The nucleation-growth of titanium oxo-alkoxy (TOA) nanoparticles was studied in n-propanol and isopropanol solvents. A common feature is quasi-instantaneous appearance of stable clusters with the hydrodynamic radius 1.6 nm, which form nanoparticles aggregated during the induction period. In contrast to clusters, the nanoparticle size and growth kinetics were affected by solvent: their size was 3.8 nm in n-propanol and 5.2 nm in isopropanol and the growth kinetics in isopropanol was significantly faster. The results suggest that the stability of the growing TOA units decreases with an increase of size, supporting the hierarchical model of the sol-gel growth.

We report on the elaboration of nanoparticulate SO42––ZrO2 solid acid catalyst for conversion of free fatty acids into biofuel. Three different morphological modifications of zirconia were prepared with the sol–gel method and compared as acid supports: polydispersed nanopowder (PNP), monodispersed nanopowder (MNP), and monodispersed nanoparticles coating (MNC). The size-selected zirconia–oxo–alkoxy (ZOA) nanoparticles of 3.6 nm diameter were prepared in a rapid micromixing reactor and either precipitated (MNP) or deposited on glass beads (MNC). The polydispersed 4/100/500 nm ZOA particles were prepared in nonparent alcohol for realization of PNP powders. The grafting of SO42– groups was realized on the three ZOA supports by wet impregnation method, and three catalysts were prepared after the subsequent drying and thermal treatment stages. The temperature of thermal treatment strongly affects the stability of the solid acid complex and serves to be an important factor of the preparation process. A strong r...

On the basis of the Departments of Oncogynecology and Radiology of the N.N. Petrov Research Institute of Oncology there was performed a comparative analysis of the results of detection of the sentinel lymph node using a fluorescent method with Indocyanine Green (ICG) and a radioisotope method with 99m-labeled colloidal radiopharmaceutical in endometrial cancer patients undergoing laparoscopic hysterectomy with lymphadenectomy from June 2016 to December 2016. The study included 19 patients with early endometrial cancer. Specificity and sensitivity of methods of radiation diagnostics (ultrasound and MRI) in the detection of metastatic involvement of pelvic lymph nodes are also presented.

A complex kinetics of the photocatalytic decomposition of gaseous ethylene on nanoparticulate Fe(III) doped anatase TiO2 was analyzed in a continuous-flow fixed-bed reactor. The analysis evidenced the production of non-volatile intermediate reaction products, which cover the photocatalyst surface and delay the time of attaining the stationary reactor performance. As a result, the reaction yield slowly increases during the long-lasted (∼3 h) intermediate stage. Based on Raman, FTIR and thermal post-treatment analyses, we assigned the major non-volatile reaction product to polymeric oxidized hydrocarbons: furan and furfural oligomers. A theoretical model is proposed explaining the observed kinetics.

Acidithiobacillus ferroxidans strains were isolated from acidophilic microbial communities of Kazakhstan sulfide ore deposits. Their biotechnologically important properties (optimal and maximal growth temperatures and resistance to NaCl) were determined. While temperature optima of the strains were the same (30-32 degrees C), temperature ranges were different. Thus, strain TFBK oxidized iron very poorly at 37 degrees C, while for strain TFV, the iron oxidation rate at this temperature was insignificantly lower than at lesser temperatures. NaCl inhibited the oxidative activity of both strains. Iron oxidation by strain TFV was inhibited at 5 g/L NaCl and was suppressed almost completely at 20 g/L. Iron oxidation by strain TFBK was inhibited by NaCl to a lesser degree, so that iron oxidation rate was relatively high at 10 g/L, while at 20 g/L NaCl the process was not suppressed completely, although the oxidation rate was low. Sulfur oxidation by these strains was less affected by NaCl than oxidation of ferrous iron. Sulfur oxidation by strain TFV was considerably inhibited only at 20 g/L NaCl, but was not suppressed completely. Sulfur oxidation by strain TFBK was more affected by NaCl. At 10 g/L NaCl the oxidation rate was much lower than at lower NaCl concentrations (sulfate concentrations after 6 days of oxidation at 5 and 10 g/L NaCl were -130 and -100 mM, respectively). While sulfur oxidation by strain TFBK was considerably inhibited at 10 and 20 g/L NaCl, similar to strain TFV it was not suppressed completely. Our results indicate the adaptation of the species A. ferrooxidans to a broad range of growth conditions.

We describe the preparation of mixed metal oxide nanoparticles of a desirable composition and their transformation to the crystalline solids ZrxTi1−xO2 (0.0 ≤ x ≤ 1.0) after heat treatment. The correlation analysis between the size of the nucleus, the crystalline phase and the elemental composition of the solid is presented. Mixed metal oxide zirconium–titanium-oxo-alkoxy (ZTOA) nanoparticles of different elemental compositions 0 ≤ x = CZr/(CZr + CTi) ≤ 1 were prepared via the sol–gel method in a reactor by rapid micromixing of n-propanol fluids containing the precursors and water. The structural transformation of the nanoparticles takes place in two temperature ranges, 210–250 °C and 380–680 °C, which sensitively depends on the elemental composition. In the range 0.3 ≤ x ≤ 0.6, stable ZTOA nanoparticles with a radius of 2.1 ± 0.05 nm appeared at the hydrolysis ratio H ≤ 1.5. The heat treatment results in a single orthorhombic ZrxTi1−xO2 phase. The crystallisation onset temperature was the highest in this range of x, attaining 680 °C at x = 0.5. In the range 0 ≤ x ≤ 0.2, the particle radius decreased to 1.6 nm for pure titanium-oxo-alkoxy nuclei (TOA, x = 0); their heat treatment resulted in a single TiO2 anatase phase. In the range 0.7 ≤ x ≤ 1, the particle radius decreased to 1.8 nm for pure zirconium-oxo-alkoxy nuclei (ZOA, x = 1); their heat treatment resulted in mixed monoclinic and tetragonal ZrO2 phases. The crystalline cell parameters of the observed phases underwent a continuous variation with x. TEM images evidenced the nanoporous structure of submicronic orthorhombic ZrxTi1−xO2 monocrystals with a mean pore size of about that of the ZTOA nanoparticles.

In Europe, rapeseed is a renewable raw material which has been widely used for the production of biodiesel by various processes. The transesterification reaction of rapeseed oil with ethanol to biodiesel in supercritical fluid conditions was investigated using several heterogeneous catalysts and preliminary ultrasonic emulsification of the reaction mixture, to run the reaction at mild conditions. Phase equilibrium of fatty acids in supercritical ethanol was study to determine the operating condition in supercritical states. Transesterification experiments were carried out under a pressure of 30 MPa, with ethanol to oil molar ratio (in the range of 12:1⿿20:1), temperature (623 K to 653 K), and the catalyst loading level and type were the main parameters. The most important characteristics of Al 2 O 3 support catalyst and the impregnation method with aqueous solution of metal nitrates are also described. Yields of Fatty Acids Ethyl Ester (FAEE) are reported for different ZnO/Al 2 O 3 , MgO/Al 2 O 3 , SrO/Al 2 O 3 catalysts in different experimental conditions. The higher yield of 97.46% was obtained under the optimal conditions 623 K, 30 MPa, 12:1 ethanol/FAEE molar ratio, with SrO/Al 2 O 3 (2 wt.% SrO) impregnated catalyst.

Oxidative conversion of ethane on the molybdenum oxide MoO3 mixed with 0–95% Al2O3, Ga2O3, or Y2O3 has been studied in the pulse mode at 600°C. It has been revealed that the components of these systems undergo strong interaction, which leads to enhanced ethane conversion and an increased selectivity for ethylene with a decrease in the MoO3 content. The 5%MoO3–95%Al2O3 system has proved the most effective in the oxidative dehydrogenation of ethane, with the selectivity for ethylene reaching 90% at an ethane conversion of 30 wt %.

Oxide systems prepared by thermal decomposition of mixtures of ammonium heptamolybdate with varying amounts of aluminum, gallium, and yttrium nitrates have been studied by thermal analysis, X-ray powder diffraction, and scanning electron microscopy. The formation processes, the nature of interaction between the components, and the states of these systems have been determined. It was shown that the nature of oxides in the molybdenum systems have a significant effect on their physicochemical properties.

Transparent Cr4+:YAG ceramics with high optical quality was fabricated using solid state reactive sintering. The effect of CaO/MgO ratio on Cr3+ →Cr4+ conversion efficiency was studied. In samples with fixed total amount of divalent ions, Cr4+ conversion efficiency is growing with increasing of Ca2+/Mg2+ ratio. Samples were fully transparent after sintering at 1840 °C for 8 h and annealing in air at 1400 °C for 10 h. Some rather specific defects were observed, their nature investigated and model of forming proposed. Most probable nature of these defects is tungsten inclusions in ceramics sourced by tungsten vapors inside the vacuum furnace. This is far more pronounced with high calcium oxide presence in ceramic samples. The main saturable absorber characteristics were systematically measured.

The decomposition of acetaldehyde was investigated in a plasma-catalytic reactor. The gold-based catalysts were obtained by growing Au nanoparticles on silica beads or plates previously coated by a titanium oxo-alkoxy monolayer. The characterization of the synthesized catalysts was carried out by SEM, AFM and UV–Visible spectroscopy. Below an exposure time to UV of 20 min, a homogeneous surface coverage by the relatively small gold nanoparticle (R

A large set (60 samples) of oxide systems containing Mo, V, Ti, Zr, Fe, Ni, Co, La, Ce, Al, Si, Sb, Bi, Nb, Sn, and Pb oxides has been obtained by synthesis. It has been found that using Al(OH)3 (instead of Al2O3) makes it possible to prepare a modified Mo system that ensures a 93–95% selectivity of ethane dehydrogenation to ethylene with a C2H6 conversion as high as 40%. These results open the possibility of purposeful and technologically easy manufacturing of molded systems containing active lattice oxygen, which is able to mediate the oxidative dehydrogenation of ethane to ethylene.

By screening a large series of oxide systems, the most effective modified Mo catalysts for oxidative dehydrogenation of ethane to ethylene with selectivity for the desired product of more than 90% have been found. Using TG–DTA and XRD techniques, it has been shown that the state of the support (Al2O3) determines the formation of active sites. The procedure for preparing microspherical Mo catalysts is characterized by simplicity and complete reproducibility of their properties. Further investigation in this line is associated with testing a pilot batch of the Mo catalyst on a pilot unit with a riser reactor.

We report on the experimental study of ultra-porous alumina (UPA) of transition phases γ and θ, which we fabricate by oxidation of laminated metallic aluminum followed by chemical and thermal treatments. Its morphology of a nanostructured monolith with up to 99% porosity brings together several crucial advantages with respect to existing aluminum oxides: an ultra-low density, the potential of refractive index gradients, and a chemically tunable hydrophilic character. Its extremely low permittivity measured here for the first time, er ≈ 1.2 at 130–165 GHz, makes UPA a promising substrate material for planar electromagnetic components in this microwave spectral range of great interest for the cosmic microwave background observation. The dielectric loss tan δ ≈ 10−3, although being relatively low, can be further reduced after a chemical treatment that conveys hydrophobic character to the UPA constituting nanofibers.

The efficiency of biooxidation for treatment of a double-refractory gold-bearing sulfide ore concentrate from the Bakyrchik deposit (East Kazakhstan) was defined. The experiments were conducted in two different modes, i.e., with the standard liquid medium and the medium imitating the chemical composition of the Bakyrchik deposit groundwater and containing high concentrations of sodium, magnesium, and chloride. The concentrate contained 17.5% of organic carbon, 6% of pyrite and 13% arsenopyrite. Gold content was 57.5 g t@-1@. Direct gold recovery by cyanidation was very low (2.8%). While biooxidation was efficient in both cases (approximately 90% of sulfide sulfur was oxidized), the efficiency of cyanidation was low (39 and 32%, respectively). This fact suggests high efficiency of biooxidation is insufficient for efficient treatment of double-refractory gold-bearing sulfide ore concentrates.

A solvothermal method of sol–gel synthesis of anatase titania in solutions of anhydrous aliphatic acids in an autoclave at 250–350°С was developed. A series of mesoporous anatase powders were produced, which size, shape and phase composition are controlled by the organic acid radical length and synthesis temperature. The organic acid acts as solvent, reagent, and template agent in the formation of TiO 2 nanocrystals. The powders show high activity towards the photocatalytic degradation of methylene blue (MB) in aqueous solutions, comparable with that of the reference Aeroxide P25 TiO 2 nanopowder.

We report on the effect of mixing on the morphology of ultrafine zinc oxide nanoparticles synthesized via a polyol process using zinc acetate and water in a diethylene glycol medium. Three mixing strategies were considered: stirred batch, T-mixer, and impinging free jets. The particle granulometry was accessed using the transmission electron microscopy and x-ray diffraction methods. The nanoparticle size and polydispersity decreased with an increase in the local dissipated energy. In particular, the polyol process conducted in the same chemical environment at 353 K did not lead to the observation of nanoparticles in the stirred batch reactor but resulted in unconventionally small 6-nm particles in the T-mixer and impinging jet configurations. This result is apparently related to the micromixing eddy geometry described by the Kolmogorov length. The hydrodynamic flow patterns and energy dissipation were obtained from computational fluid dynamics simulations, which are essential in the design, optimization, and scale-up of the polyol process. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1708–1721, 2015

With a presumed steady decline of gold ore grade in mineral resources, mining applications enabling efficient metal extraction from low-grade ores are of increasing interest to the minerals industry. Microbial processes may provide one such solution since they can participate in the biogeochemical cycling of gold in many direct and indirect ways. This review examines current literature on the role of microorganisms in gold processing and recovery. The review covers aspects such as the biotechnical pretreatment of gold ores and concentrates, microbially catalysed permeability enhancement of ore bodies, gold solubilisation through biooxidation and complexation with biogenic lixiviants, and microbially mediated gold recovery and loss from leach liquors.

In this work, the preparation of hybrid oxo-TiO2 nanoparticles modified by salicylic acid (SA) is reported. The size-selected TiO2 nanoparticles were synthesized in a sol-gel reactor with rapid micromixing of reagents and binding of SA molecules occurs at the nucleation stage. UV-visible absorption, Raman spectroscopy and Light scattering measurements evidence the formation of a SA–oxo-TiO2 charge-transfer complex. In particularly, the C O vibration mode of SA shifts to lower frequencies upon complexation while the C-O vibration modes of both carboxylate and phenolic groups retain their position. The absence of C-O shift comes from two effects that cancel each other, i.e. the hardening of this mode related to the C O mode changes and its softening due to the replacement of hydrogen in COH group by Ti atoms. Kinetic studies of the oxo-TiO2 nanoparticles nucleation and growth in presence of SA show that the acidic ligand at the nanoparticle surface acts as an attractor for another oxo-TiO2 nanoparticle leading to polycondensation. This mechanism is responsible for the acceleration of the nanoparticle aggregation kinetics and shortening of the induction time. The hybrid nanoparticles are stable at pH ≤ 7.7 and release SA molecules at pH ≥ 8.5.

Experiments on atmosphere mixing and stratification in the large scale experimental facility (PANDA), where the initial helium stratification in a vessel is eroded by a vertical jet of steam, were simulated with the CABARET scheme. Good agreement between calculated and measured gas temperature and concentrations has been achieved by refining the mesh and adding the model of radiative heat transfer. The simulation results are presented and discussed.

The efficiency of the process coupling a dielectric barrier discharge and a fluidized nanostructured silver-based bed for the degradation of a model pollutant (acetaldehyde CH 3 CHO) is presented. The deposition of silver nanoparticles has been realized by photocatalytic reduction of Ag + ions in aqueous solution of silver nitrate salt on TiO 2 nanoparticles deposited on SiO 2 beads. In the first part, the efficiency of the plasma alone process is discussed, in terms of pollutant removal and CO and CO 2 production. The main pathways of pollutant degradation and CO x production are discussed. In the second part, CH 3 CHO removal as well as CO x production is studied as a function of the photocatalytic reduction time of Ag + ions, which is related to the deposited silver mass. Finally, pollutant removal pathways, including homogeneous chemistry in the plasma phase and heterogeneous chemistry on the surface, are discussed.

We report on a new method of preparation of AgN-TiO2 nanoparticulate coatings with stable and highly reproducible morphology. The silver nanoparticles are grown on monolayer titanium-oxo-alkoxy nanoparticulate coatings by silver ions reduction at UV-A light illumination. Their size and surface number density increase with the irradiation time. The AFM and high-resolution SEM and TEM measurements of height (h) and lateral size (D) of the silver nanoparticles show that their shape approaches spherical segment with h/D = 1/4 at long irradiation times. The size correspondent to the maximum of the particles size distribution curve tends to D = 12 nm with half width at full-maximum ΔD = 4 nm. The evaluation of the deposited silver mass results in the quantum yield of the deposition process close to 100% at the process beginning and the atomic surface density of NAg = 1.25 × 107 at/μm2 at the process saturation. The absorption spectra of the surface plasmon shift from 425 to 525 nm. The spectra are successfully ...

Monodispersed zirconium oxo-alkoxy nanoparticles are synthesized via a sol–gel method in a rapid micromixing reactor with in situ particle size measurements. The nucleated nanoparticles of 4.7 nm diameter are free from impurities and conserve high chemical activity. They can be associated in 1D fractals. These nanoparticles can form high optical-quality coatings on hydrophilic substrates.

International audience; Photoluminescence (PL) of photochromic pHEMA-TiO2 gels-based hybrids was studied by means of time- and energy-resolved spectroscopy at temperatures between 300 K and 10 K. The PL band at 485 nm is assigned to S0←T1 transition of methoxyphenol (organic molecule added to the commercial monomer hydroxyethyl methacrylate, HEMA and used as an inhibitor of spontaneous polymerisation) in the polymer environment, while the PL band at 600 nm is assigned to the self-trapped exciton onto octahedral TiO6 site of the inorganic component. The mechanisms of the excited states population are discussed. In particular it is shown that both singlet-triplet energy transfer in methoxyphenol and methoxyphenol–TiO2 charge transfer are strongly affected by the material composition and temperature. The hypothesis about the photoexcited holes annihilation with the trapped electrons is confirmed to be one of main mechanisms limiting the Ti3+ centres concentration.

The dynamics of relaxation processes for single-type Au nanoparticles in the form of aqueous colloid and nanoparticles embedded in a TiO2 film have been investigated by femtosecond laser photolysis techniques. It has been shown that the theoretical models successfully applied to the description of the shape and dynamics of the differential spectra induced by a femtosecond pulse in Au nanoparticles in a dielectric are not sufficient to describe the differential spectra in the case of Au nanoparticles embedded a wide-bandgap semiconductor matrix. Evidence is presented for electron transfer from Au to TiO2 upon excitation of plasmon resonance in Au. In this case, the electron transfer between the Au nanoparticle and TiO2 results in a change in the pattern of differential spectra and influences the time evolution of the pattern.

We report on the preparation of a new photocatalyst by impregnation of size-selected TiO2 nanoparticles into monolithic ultraporous alumina of θ and α polymorphs. The alumina matrix is prepared by selective surface oxidation of liquid Hg-alloys in a humid atmosphere at room temperature with subsequent annealing at 1100–1300 °C. An additional treatment with trimethylethoxysilane was used to mechanically reinforce the ultraporous structure. Monodispersed titanium-oxo-alkoxy nanoparticles were generated in a sol–gel reactor with rapid micromixing, then deposited by liquid colloid impregnation and thermally treated above 350 °C to form anatase TiO2. High-resolution TEM images show evidence of non-aggregated 5-nm nanoparticles in θ-alumina matrix at a mass loading of 26 wt.%, which conserve their anatase crystalline structure after the thermal treatment at temperatures as high as 1000 °C. The rutile phase appears only at T ≥ 1100 °C when particle size increases to ∼17 nm due to the aggregation. The photocatalytic activity (ethylene decomposition) of the non-aggregated nanoparticles is conserved over a wide temperature range, and it decreases as soon as the aggregation takes place.

We report on photocatalytic activity of new homogeneously Fe(III)-doped TiO 2 nanocoatings. The material is prepared in a two-stage process including (1) oxo-TiO 2 nanoparticles nucleation, doping by iron(acetylacetonate) 3 and reactive deposition on glass substrates in a sol–gel micromixing reactor and (2) thermal treatment. The photocatalytic test of the nanocoatings is conducted on ethylene degradation in a continuous-flow fixed bead reactor. The catalyst shows the best performance at Fe/Ti molar ratio of 0.005 at.%, which is explained by a competition between VB-hole localisation on Fe 3+ and its annihilation on Fe 2+ . The proposed model permits an estimation of the localisation distance of the CB-electron in anatase TiO 2 after a photoexcitation and defines the optimal size for the nanoparticulate TiO 2 photocatalyst to be ∼8 nm.

The problems of synthesis gas manufacture in relation to the thermochemical characteristics of the interaction of hydrocarbons with various oxidants (H2O, CO2, O2), coke formation, and catalyst deactivation are considered. Prospects for the partial oxidation of hydrocarbons have been discussed in light of recent developments in the field of oxygen-permeable membrane materials. Data on oxide systems containing active lattice oxygen are presented, which opens the possibility of manufacturing synthesis gas from hydrocarbon mixtures, in particular, from associated gas.

When surfactants are present in polishing compositions severe damage is done to the initial crystal structure of a very thin (tenths and hundredths of a micron thick) surface layer of the material (silicon) being processed and the deformation-strength properties of the material change as a result of the Rebinder effect. The use of active additives in polishing compositions, including unconventional ones, makes it possible to decrease the thickness of the damaged layer by a factor of 1.5 – 2, significantly increasing the polishing efficiency in the process.

Pure and doped nanocoatings were prepared of from chemically active TiO2 colloids. The colloids are generated in sol–gel reactor with turbulent mixing of two reactive fluids, containing titanium tetra-isopropoxide and water, in T-mixer. The particle size is measured by the light-scattering technique using optical-fibre probe. The TiO2 nanoparticles doped with nitrogen are obtained by the injection of a doping agent into the reaction zone at the mixing stage. The mixing at the nucleation stage has a strong impact on the nanoparticles polydispersity and mean size. The prepared nanocoatings show photocatalytic activity under UV and visible light illumination.

Zinc oxide monodispersed nanoparticles were synthesized using a modified polyol process without any requirement to use a catalyst or calcination step at high temperature. The morphology and the size of the resulting oxide particles were adjusted by using several synthesis parameters (temperature, alkaline ratio, hydrolysis ratio, etc.). The increasing of the alkaline ratio results in a great change of the elaborated particles morphology that evolved from irregular and anisotropic forms (conical, nanorod-like and elliptical) to spherical one. A growth mechanism of these particles was proposed on the basis of zincite crystal structure and the morphology evolution as a function of the synthesis parameters. The photoluminescence spectra show UV-excitonic and visible emission bands. The strongest intensity of the visible emission was observed in nanorod-like particles, which implies an increased fraction of oxygen vacancies in this sample. The rod-like particles with 1 μm length show the dominant UV-emission, which evidences their improved stoichiometry.