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Carbon dots keep attracting attention in multidisciplinary fields, motivating the development of new compounds. Phenylenediamine C6H4(NH2)2 dots are known to exhibit colorful emission, which depends on size, composition, and the functional surface groups, forming those structures. While quite a few fabrication protocols have been developed, the quantum yield of phenylenediamine dots still does not exceed 50% owing to undesired fragment formation during carbonization. Here, we demonstrate that an ethylene glycol-based environment allows obtaining multicolor high-quantum-yield phenylenediamine carbon dots. In particular, a kinetic realization of solvothermal synthesis in acidic environments enhances carbonization reaction yield for meta phenylenediamine compounds and leads to quantum yields, exciting 60%. Reaction yield after the product's purification approaches 90%. Furthermore, proximity of metal ions (Nd3+, Co3+, La3+) can either enhance or quench the emission, depending on the concentration. Optical monitoring of the solution allows performing an accurate detection of ions at picomolar concentrations. An atomistic model of carbon dots was developed to confirm that the functional surface group positioning within the molecular structure has a major impact on dots' physicochemical properties. The high performance of new carbon dots paves the way toward their integration in numerous applications, including imaging, sensing, and therapeutics.

Improving the production efficiency is the task with the increasing difficulty. Therefore, it is important to constantly expand the set of tools and perfect the methodology for improving the processes. Some of the losses associated with the negative technological events (breaks, drifting, etc.) are difficult to eliminate completely due to the complexity of making changes to the basic technology. But if you know in advance that the event will occur, you can significantly reduce the probability and consequences, thereby significantly improve the efficiency of the production process. Therefore, it is important to develop and introduce the applied approaches to forecasting the negative technological events in the production processes. This paper presents the method of the forecast-event statistical analysis of the cause-and-effect relationships. The technique was tested on the events of strip’s breakage during rolling at the cold rolling mill 1400 and strip’s drifting in the input storage of the continuous etching unit (CEU). Based on the presented methodology, the specialized digital service was developed and introduced in the production processes of the dynamo steels shop.

Composite ceramics of titanium nitride grains incorporated in an aluminium nitride matrix have been synthesized by high pressure high temperature treatment of a mechanical mixture of AlN–TiN (3 mol % TiN) powders. The microstructure of the samples analysed by means of electron beam microanalysis and Raman spectroscopy shows that the formation of cubic AlN in the composite begins near titanium nitride grains. The areas of mixed chemical composition, which can be assigned to the formation of the solid solutions Al1−xTixN, have been observed at the phase interfaces. The luminescence properties of AlN–TiN ceramics have been considered focusing on the choice of high pressure and high temperature treatment conditions. Three main components at 2.0 eV, 2.4 eV and 3.1 eV are revealed in the cathodoluminescence spectra analysed quantitatively. The observed emission originates from the radiative transitions with participation of valence band states, oxygen-vacancy centres (VAl–ON), nitrogen vacancies VN, and shallow donors which form a complex system of energy levels in the bandgap of the wurtzite-type AlN.

Metasurfaces, based on subwavelength structuring, provide a versatile platform for wavefront manipulation in an ultrathin form factor. The manufacturing of metasurfaces, however, generally requires...

The usage of silver as a filtering material for removal of iodine from the gas phase of a lead–bismuth eutectic based nuclear reactor was investigated in various atmospheres representing normal operation as well as accident conditions. Thermochromatography experiments were performed to quantify the retention experienced on a silver surface by iodine species evaporated from a lead–bismuth eutectic sample. Measured adsorption enthalpies ranged from −171 to − 208 kJ mol−1 with observed differences attributed to various surface effects rather than a change in iodine speciation. The postulated adsorption mechanism is chemisorption of iodine atoms on the silver surface. Metallic silver fulfills the desired criteria for a capturing material in water-free filtering systems to be used as an alternative to traditional alkaline scrubbers commonly used in LWR systems.

Iodine evaporated from lead–bismuth eutectic (LBE) has been examined with respect to its adsorption behavior on stainless steel in various gases to establish a base for safety evaluations on LBE based nuclear reactors. In inert conditions the iodine forms a single species with an adsorption enthalpy between − 97 and − 106 kJ/mol. The adsorbed species is tentatively identified as bismuth monoiodide, BiI. Addition of moisture to the inert gas has no substantial influence on the adsorption behaviour. For the reducing hydrogen carrier gas depositions with adsorption enthalpies ranging from − 87 to − 134 kJ/mol were observed in dry and water saturated conditions. The larger variation of adsorption enthalpies compared to analogous experiments in helium likely result from surface effects induced by the reactive gas. Formation of highly volatile species such as hydrogen iodide HI was not observed. In oxidizing conditions multiple iodine species with adsorption enthalpies ranging from − 67 to − 83 kJ/mol were observed, with the exception of one experiment where only a lower limit of –ΔHads

Here, the synthesis of holey carbonylated (C-ny) graphene derivative and its application for gas sensing is demonstrated. The carbonylation of graphene oxide leads to the 3-fold increase in the concentration of carbonyl groups’ up to 9 at.% with a substantial elimination of other oxygen functionalities. Such a chemical modification is accompanied by the perforation of the graphene layer with the appearance of matrices of nanoscale holes, leading to corrugation of the layer and its sectioning into localized domains of the π-conjugated network. Combined with the predominant presence of carbonyls, granting the specificity in gas molecules adsorption, these features result in the enhanced gas sensing properties of C-ny graphene at room temperature with a selective response to NH3. Opposite chemiresistive response towards ammonia when compared to other analytes, such as ethanol, acetone, CO2, is demonstrated for the C-ny graphene layer both in humid and dry air background. Moreover, a selective discrimination of all of the studied analytes is further approached by employing a vector signal generated by C-ny multielectrode chip. Comparing the experimental results with the calculations performed in framework of density functional theory, we clarify the effect of partial charge transfer caused by water and ammonia adsorption on the chemiresistive response.

Large-size vertical β -Ga2O3 Schottky barrier diodes (SBDs) with various device areas were demonstrated on a Si-doped n -type drift layer grown by hydride vapor phase epitaxy (HVPE) on bulk Sn-doped (001) n -type β -Ga2O3 substrate. In this letter, the devices have two circular contacts with a diameter of 1500 and 500 μm and two square contacts with dimensions of 1600 × 1600 μm2 and 800 × 800 μm2, corresponding to the area of 0.2 × 10−2 cm2 (the smallest device), 0.6 × 10−2, 1.8 × 10−2, and 2.6 × 10−2 cm2 (the largest device). The breakdown voltage ( BV ) was determined to be −261 V for the largest device and −427 V for the smallest device. Also, the ideality factor ( η ) of vertical Ga2O3 SBDs with different device areas exhibited the same value of 1.07, except for the largest device area of 2.6 × 10−2 cm2 with an ideality factor of 1.21. At an applied forward bias of VF = 2 V, the specific on -state resistance ( RonA ) of all the Ga2O3 SBDs remains relatively low with values ranging from 1.43 × 10−2 Ω cm2 to 7.73 × 10−2 Ω cm2. The measured turn- on voltage ( Von ) of all the SBDs remains low with a narrow distribution.

Based on published data and experimental studies of formation regularities of aluminium hydroxide, a reproducible technique for synthesis of bayerite-structured aluminium hydroxide by precipitation was developed as a part of the creation of preparation technology of chromia-alumina dehydrogenation catalyst. A possibility of synthesis of high purity bayerite (above 90 wt.%) with different particle sizes depending on synthesis conditions was shown. A correlation between dispersion of the sediments and synthesis temperature was shown, the optimal precipitation temperature – which allows obtaining bayerite with a sufficiently large particle size and high purity – was found. Based on the experiments, a fundamental difference between technologies and products of precipitation by sodium hydroxide and aqueous ammonia was shown. The influence of duration of precipitation stages on the properties of sediments is analyzed from the standpoint of theory of relative supersaturation

The report presents the results of the development of dental films with ketorolac trometamine based on the natural biodegradable polymers from the groups of sodium alginates and xanthan gums in combination with lightly crosslinked acrylic polymer carbopol. Physicochemical properties, such as moisture, mucoadhesion, thickness, tensile strength, disintegration in phosphate buffer were determined in obtained samples of this dosage form. A comparison of physicochemical properties of experimental samples and commercial model of dental film has allowed establishing the perspective composition of complex matrix of films with ketorolac trometamine for use in dentistry.

Luminescent liquid crystals (LLCs) attract considerable attention because of their broad applications in displays, chemosensors, and anti-counterfeiting. However, it remains challenging to achieve a high luminescence efficiency in LCs because of the common aggregation-caused quenching effect. Herein, we demonstrate a facile approach to designing LLCs with a high quantum yield up to 88% by deliberately tuning the aggregation behavior of platinum(II) complexes with alkoxy chains (CnH2n+1O-). LLCs in hexagonal columnar and rectangular columnar phases are achieved when n = 12 and 16, respectively, as revealed by one-dimensional wide-angle X-ray diffraction and small-angle X-ray scattering. These LLCs are able to not only exhibit strong emission at elevated temperatures but also show attractive reversible vapochromism upon alternative CH2Cl2 and EtOH fuming, which imparts added functions and promises technological utility.

In the paper there are shown the investigation results of the mode range of selective laser melting process in the course of which is achieved minimum porosity in samples grown from aluminum powder. The estimate of hardness in different areas of samples is carried out, a single melted track formation is considered. The results have practical significance for the growth aluminum alloy products with the specified structure.

The article discusses the description of one of the optical methods for determining the parameters of fuel atomization in atmospheric conditions and recording the results using a high-speed video camera. The possibility of interpreting images of a fuel jet in development over time as the distribution of the concentration of a dispersed medium with a constant volume-surface diameter (Sauter), which is an optical method for controlling fuel atomization, is shown.

The crystal structure of the title compound has been determined. The molecule is non-planar, the dihedral angle between the phenyl rings is equal to 84.2(10)°. In crystal, weak C-H…O hydrogen bonds...

This article outlines the main results of a research and development cooperation between Philips Research Eindhoven; Peter the Great St. Petersburg Polytechnic University; Ioffe Institute, St. Petersburg; Utrecht University; and Philips Healthcare. It reviews the properties of garnet ceramics in the (Lu,Gd)3(Ga,Al)5O12:Ce system for medical imaging, especially time-of-flight positron emission tomography (PET). Thermally stimulated luminescence (TSL) peaks are attributed to impurities, verified by intentional codoping of samples. A lately developed method allows extraction of carrier lifetimes, thermal trap depths, and frequency factors from TSL and afterglow measurements. A detailed analysis reveals the presence of a distribution of trap depths, allowing a more accurate afterglow modeling. Activation energies of thermal ionization and trap depths obtained from TSL show the influence of Ga/Al substitution on thermal quenching and on trap position. The resulting nonmonotonic dependence of the conduction band edge with Ga content in (Lu,Gd) garnets is consistent with earlier predictions. Shallow traps determine both signal decay and short-term afterglow. The impact of signal height, rise, and decay times on coincidence resolving time and further on PET image quality is described by analytical models.

Improving building energy performance requires the development of new highly insulative materials. An affordable retrofitting solution comprising a thin film could improve the resistance to heat flow in both residential and commercial buildings and reduce overall energy consumption. Here, we propose cellulose aerogel films formed from pellicles produced by the bacteria Gluconacetobacter hansenii as insulation materials. We studied the impact of the density and nanostructure on the aerogels' thermal properties. A thermal conductivity as low as 13 mW/(K·m) was measured for native pellicle-based aerogels that were dried as-is with minimal post-treatment. The use of waste from the beer brewing industry as a solution to grow the pellicle maintained the cellulose yield obtained with standard Hestrin-Schramm media, making our product more affordable and sustainable. In the future, our work can be extended through further diversification of food wastes as the substrate sources, facilitating higher potential production and larger applications.

Optical gas sensing attracts growing attention in the recent years. This is governed by progressive availability of optical nanostructures fabrication and complex techniques of optical spectrum processing. In the present paper, a room-temperature optical humidity sensor based on a hydrophilic polymer Nafion is theoretically and experimentally investigated. Sensor geometry is optimized for maximum sensitivity of an angle-resolved ATR dip in the Kretschmann configuration. The reflectance dip is attributed to the 2nd order Nafion layer leaky waveguide mode hybridized with the surface plasmon-polariton at the silver/Nafion interface. Results of the relative humidity (RH) retrieval with the regression of the physical model parameters is compared to these obtained with different machine learning (ML) techniques. It is shown that a limited raw data set is enough for using ML algorithms. Accuracy of 0.3% has been demonstrated in RH measurements.

In this work, we present the design, fabrication, optimization, and experimental results of a high-efficiency planar solar thermophotovoltaic (STPV) system utilizing a micro-textured absorber and a nanostructure multilayer metal-dielectric coated selective emitter fabricated on a tungsten (W) substrate. Light absorptance of more than 90% was achieved at visible and near-infrared wavelengths using the microtextured absorbing surface. The nanostructure selective emitter consists of two thin-film optical coatings of silicon nitride (Si3N4) and a layer of W in between to increase the surface emissivity in spectral regimes matching the quantum efficiency of the thermophotovoltaic (TPV) cells. Gallium antimonide (GaSb)-based TPV cells are used in our STPV design. The experiment was conducted at different operating temperatures using a high-power continuous wave laser diode stack as a simulated source of concentrated incident radiation. Our experimental setup measured a maximum electrical output power density of 1.71 W/cm2 at 1676 K STPV temperature, and the overall power conversion efficiency of 8.4% after normalizing the output power density to the emitter area. This is the highest STPV system efficiency reported so far for any experimental STPV device. The incident optical laser power on the absorber side was 131 W. This is equivalent to a solar concentration factor of ~2100, which is within the practical limit and readily achievable with Fresnel lens setup.

Colloidal interactions in nematic liquid crystals can be described as interactions between elastic multipoles that depend on particle shape, topology, chirality, boundary conditions and induced topological defects. Here, we describe a nematic colloidal system consisting of mesostructures of gold capable of inducing elastic multipoles of different order. Elastic monopoles are formed by relatively large asymmetric mesoflower particles, for which gravity and elastic torque balancing yields monopole-type interactions. High-order multipoles are instead formed by smaller mesoflowers with a myriad of shapes corresponding to multipoles of different orders, consistent with our computer simulations based on free energy minimization. We reveal unexpected many-body interactions in this colloidal system, ranging from de-mixing of elastic monopoles to a zoo of unusual colloidal crystals formed by high-order multipoles like hexadecapoles. Our findings show that gold mesoflowers may serve as a designer toolkit for engineering colloidal interaction and self-assembly, potentially exceeding that in atomic and molecular systems., Elasticity-mediated particle interaction in a hosting medium holds promise for material engineering of unusual structures. Yuan et al. show that the gold microparticles can induce elastic multipoles of different symmetries when dispersed in a nematic liquid crystal as building blocks for various crystals.

The electron conductors Sr0.5Ca0.5Mn1−xVxO3−δ (x = 0.025, 0.05, and 0.1) synthesized via the citrate–nitrate route have been characterized by powder X-ray diffraction at room temperature and at high temperatures in air. At room temperature, the symmetry of unit cells of corresponding morphotropes change from orthorhombic (space group Pbnm) to tetragonal (space group I4/mcm) due to the cooperative Jahn–Teller effect. In samples with x = 0.05 and x = 0.10, the temperature of phase transition from the orthorhombic (space group Pbnm) to tetragonal (space group I4/mcm) polymorph is found to decrease with the increasing vanadium content. The phase transition from tetragonal to cubic (I4/mcm ↔ Pmm) in all samples occur around 673 K. The electrical conductivity (σ) and Seebeck coefficient (S) have been measured in air within 330–1220 K. The increase in absolute values of S with rising temperature is explained employing the model of motion of small polarons, considering the disproportionation of Mn3+ ions to Mn2+ and Mn4+ and the spin direction of t2g-electrons of manganese. The obtained data allow the calculation for the concentration and mobility of charge carriers. The decrease in enthalpy of disproportionation reaction and mobility activation energy is associated with the declining trend of Jahn–Teller distortions following polymorphic transitions with increasing temperature or morphotropic transitions I4/mcm → Pbnm at low temperatures.

Semiconductor nanowires exhibit numerous capabilities to advance the development of future optoelectronic devices. Among the III-V material family, gallium phosphide (GaP) is an attractive platform with low optical absorption and high nonlinear susceptibility, making it especially promising for nanophotonic applications. However, investigation of single nanostructures and their waveguiding properties remains challenging owing to typically planar experimental arrangements. Here we study the linear and nonlinear waveguiding optical properties of a single GaP nanowire in a special experimental layout, where an optically trapped structure is aligned along its major axis. We demonstrate efficient second harmonic generation in individual nanowires and unravel phase matching conditions, linking between linear guiding properties of the structure and its nonlinear tensorial susceptibility. The capability to pick up single nanowires, sort them with the aid of optomechanical manipulation and accurately position pre-tested structures opens a new avenue for the generation of optoelectronic origami-type devices.

Self-assembly of surfactant molecules drives changes of liquid crystal molecular alignment around droplets in nematic emulsions., Emulsions comprising isotropic fluid drops within a nematic host are of interest for applications ranging from biodetection to smart windows, which rely on changes of molecular alignment structures around the drops in response to chemical, thermal, electric, and other stimuli. We show that absorption or desorption of trace amounts of common surfactants can drive continuous transformations of elastic multipoles induced by the droplets within the uniformly aligned nematic host. Out-of-equilibrium dynamics of director structures emerge from a controlled self-assembly or desorption of different surfactants at the drop-nematic interfaces, with ensuing forward and reverse transformations between elastic dipoles, quadrupoles, octupoles, and hexadecapoles. We characterize intertransformations of droplet-induced surface and bulk defects, probe elastic pair interactions, and discuss emergent prospects for fundamental science and applications of the reconfigurable nematic emulsions.

Many promising approaches for designing interactions of synthetic materials with light involve solid optical monocrystals and nanofabricated photonic crystal structures with spatially periodic variations of refractive index. Although their high costs limit current technological applications, remarkably, such photonic and optically anisotropic materials have also evolved throughout nature and enable narrow or broad-band spectral reflection of light. Here we use self-assembly of biomaterial cellulose nanocrystals to obtain three-layer films with helicoidal and nematic-like organization of the cellulose nanoparticles, which mimics naturally occurring polarization-insensitive reflectors found in the wings of Plusiotis resplendens beetles. These films were characterized with polarized optical microscopy and circular dichroism spectrometry, as well as scanning and transmission electron microscopies. These films exhibit high reflectivity tunable within the visible and near-infrared regions of the optical spectrum and may find applications ranging from color filters to smart cloth designs and in solar-gain-regulating building technologies.

The particle size distribution significantly affects the material properties of the additively manufactured parts. In this work, the influence of bimodal powder containing nano- and micro-scale particles on microstructure and materials properties is studied. Moreover, to study the effect of the protective atmosphere, the test samples were additively manufactured from 316L stainless steel powder in argon and nitrogen. The samples fabricated from the bimodal powder demonstrate a finer subgrain structure, regardless of protective atmospheres and an increase in the Vickers microhardness, which is in accordance with the Hall-Petch relation. The porosity analysis revealed the deterioration in the quality of as-built parts due to the poor powder flowability. The surface roughness of fabricated samples was the same regardless of the powder feedstock materials used and protective atmospheres. The results suggest that the improvement of mechanical properties is achieved by adding a nano-dispersed fraction, which dramatically increases the total surface area, thereby contributing to the nitrogen absorption by the material.

Evaporative self-assembly of noble metal nanoparticles into ordered structures holds great promise for fabricating optical and plasmonic devices by virtue of its low cost, high efficiency, and ease of operation. However, poor control of Marangoni flows is one of the challenges accounting for realizing a well-defined assembly. Herein, based on the theoretical analysis of the influence of evaporative intensity on the assembly, two simple but reliable flow-field-confinement platforms are designed to control the evaporative microflows and to work concurrently with depletion forces to enable the regulated self-assembly of gold nanorods. Orientationally ordered assemblies are realized by the designed strong unidirectional microflow in a capillary, and a device-scale assembly of monolayer membrane is obtained by the created weak convection in homemade glass cells. Morphologically diversified superstructure assemblies, such as spherulite-like, boundary-twisted, chiral spiral assemblies, and merging membranes with a π-twisted domain wall, are obtained due to the spontaneous symmetry breaking or in the presence of defects, such as surface steps and screw dislocations. Optical anisotropy and polarization-dependent behaviors of these assemblies are further revealed, implying the potential applications in plasmonic coupling devices and optoelectronic components. An understanding of the entropy-driven assembly behaviors and control of evaporative microflows to guide the self-assembly of gold nanorods provides insights into the general bottom-up approach that is helpful for constructing complex yet robust nanosuperstructures.

Electrochemical biosensors utilizing nanomaterials have received widespread attention in pathogen detection and monitoring. Here, the potential of different nanomaterials and electrochemical technologies is reviewed for the development of novel diagnostic devices for the detection of foodborne pathogens and their biomarkers. The overview covers basic electrochemical methods and means for electrode functionalization, utilization of nanomaterials that include quantum dots, gold, silver and magnetic nanoparticles, carbon nanomaterials (carbon and graphene quantum dots, carbon nanotubes, graphene and reduced graphene oxide, graphene nanoplatelets, laser-induced graphene), metal oxides (nanoparticles, 2D and 3D nanostructures) and other 2D nanomaterials. Moreover, the current and future landscape of synergic effects of nanocomposites combining different nanomaterials is provided to illustrate how the limitations of traditional technologies can be overcome to design rapid, ultrasensitive, specific and affordable biosensors.

Heating, ventilation, and air conditioning of buildings account for about 15% of the global energy consumption, but about 20% of this building-related energy is lost because of inefficient windows. Greenhouse emissions associated with producing and using this energy contribute substantially to climate change. Is there a solution to this challenging problem? Starting from the physical principles associated with energy loss through windows, I will describe our development of visibly transparent, infrared-reflecting, thermally super-insulating materials that may replace or retrofit the inefficient windowpanes of residential and commercial buildings. I will discuss how production of such unusual transparent porous materials is enabled by mesoscale templating of orderly porous structures using lyotropic surfactant-based liquid crystals. I will discuss how these metamaterials can boos energy efficiency of windows and buildings in general.

The organization of nanocolloidal liquid crystals in constrained geometries has fundamental and practical importance, since under confinement, liquid crystals contain stable topological defects that can serve as templates for nanoparticle organization. Three-dimensional confinement of cholesteric (Ch) liquid crystals formed by cellulose nanocrystals (CNCs) have been extensively studied; however, their two-dimensional confinement remains under-investigated. Here, we report the results of systematic experimental studies of two-dimensional confinement of Ch-CNC liquid crystal in cylindrical capillaries with varying inner diameters. Confinement resulted in phase separation of the Ch-CNC liquid crystal into a Ch shell formed by concentric CNC pseudolayers with the helicoidal axis perpendicular to the inner surface of the capillary walls, and a micrometer-diameter isotropic core thread running parallel to the long axis of the capillary. The morphology of the confined Ch-CNC liquid crystal varied when progressively increasing the degree confinement. Finally, we show that phase separation of the Ch-CNC liquid crystal into a Ch shell and an isotropic core is preserved in flexible capillary tubing, suggesting the applicability of this system for the fabrication of flexible optical waveguides.

Due to their chemical inertness, wide operating temperature range, and low volatility, non-polar dimethyl-and methylphenyl polysiloxanes are some of the most frequently used stationary phases in gas chromatographic practice. Commercial multicapillary columns with polydimethylsiloxanes SE-30 (or OV-1) and phenyldimethylsiloxanes SE-54 (or OV-5) are well known, but their upper operating limit is 250°C, which is significantly lower than the stated thermal stability of the stationary phases themselves. The high-efficientmulticapillary column preparation method using the polyethylene glycol stationary phase and the sol-geltechnology was proposed earlier. This method allows to increase the thermal stability and to reduce the column bleed. The possibility of coating the multicapillary columns with non-polar silicone stationary phasesusing the sol-gel method was examined in order to prepare the columns with improved performance characteristics.In the current study, straight multichannel hexagonal tubes with an apothem of 2.2 mm and a capillarydiameter of ~40 μm were used as the source material. The precursor used for the application of polydimethylsiloxane was prepared from OH-terminated polysiloxane PS 347.5 and polymethylhydrosiloxane, with trimethoxymethylsilane as a crosslinking agent, and trifluoroacetic acid as a catalyst. The precursor composed of the stationary phase SE-54, trimethoxymethylsilane and trifluoroacetic acid and methylene chloride was used for the applying of SE-54. After adding all the components, the mixture was kept for a while for the sol-gel to be ready.The static low-pressure application of the PS 347.5 stationary phase from a solution obtained by dilutingof the corresponding precursor with hexane or chloroform led to an unsatisfactory result, due to capillaryblockage during the solvent removal. Under similar conditions, the use of the SE-54 stationary phasebased sol-gel provided for the smooth coating procedure, however the obtained columns lacked efficiency.The stationary phase immobilization degree for various columns ranged within 49-77%, which is less than isdesirable for the stable work of the column. Since the static coating method did not allow to produce multicapillary columns with satisfactory characteristics, attempts were made to use the dynamic method of applying stationary phases to multicapillary columns.It is theoretically shown that dynamic coating performed by moving a short plug of a stationaryphase solution along a multicapillary is correlated, that is, the thickness of the resulting film in the capillarydepends on its cross-section, and a thicker film of the stationary phase forms in the wider capillary.It was established experimentally that with the speed of the undiluted precursor plug within14-20 and 37-45 mm/s for the stationary phases PS 347.5 and SE-54, respectively, after dynamic coating andsubsequent conditioning, multicapillary columns with high efficiency were obtained (3200-3500 theoreticalplates on dodecane). In both cases, the process suffered from insufficient reproducibility, often inefficientcolumns were obtained, and the shape of chromatographic peaks also frequently differed from the Gaussiancurve. A comparison of the commercial SE-30 column with one of the columns prepared with the PS 347.5stationary phase showed the closeness of their chromatographic characteristics. However, the latter hadslightly higher polarity.Using a freshly prepared sol-gel, the immobilization degree of the stationary phase for the studiedcolumns was 86-92 and 90-97% for silicones PS347.5 and SE-54, respectively. The prepared columnsshowed a slight activity to alcohols. This may be due to the presence of free silanol groups in the products ofthe hydrolysis and polycondensation of trimethoxymethylsilane.It was shown that columns with both types of stationary phases withstand heating in an inert gasflow for several hours at 300°C without significant loss of efficiency. It was established that for the sol-gelmulticapillary columns at 300°C the bleed level (caused by stationary phase breaking down) is about an orderof magnitude lower than that of commercial columns with similar stationary phases. The increased thermalstability and lower bleed of the columns can be explained by the formation of a stable spatial organicinorganic copolymer of polysilicic acid and polysiloxanes on the capillary surface.

The actuation and levitation of air-suspended objects by a magnetic field, due to its noncontact and holonomic manipulation modes, are important technological capabilities for device applications. However, owing to a higher density of conventional ferromagnets or nanoparticle-containing polymers and strong magnetic fields required for actuation, fabricating lightweight materials with a sensitive magnetic response for weight critical applications is challenging. Here, we report ultralight aerogel-based magnets (aero-magnets) comprising assembled ferromagnetic nanomaterials with highly magnetic anisotropy where the magnetic domains can be programmed by external predesigned fields. To demonstrate the breadth of manufacturing methods for this breed of aero-magnet composites, both silica/nanocellulose aerogel hosts and ferromagnetic nanorod/nanoplatelet guests have been explored. Single and double domains with out-of-plane magnetization are programmed into the aero-magnets and characterized by magnetic force microscopy. The levitation and actuation of the aero-magnets are realized while exposed to a small external magnetic field of 11 mT and introduced to a switching circuit. Furthermore, the elastic moduli of the aero-magnets are estimated by dynamic magnetic responses of the ferromagnetic nanoparticles tightly tethered in the aerogel hosts under rapid cyclic fields. These programmable aero-magnets could serve as monolithic magnetic actuator units in the fields of tiny robots and aerospace components.

Nowadays, the decision on the creation of ecological, bio positive, energy-saving, comfortable homes and living conditions is becoming more relevant. To achieve this goal, a new technological line, allowing the production of the necessary construction elements made of straw with the stated requirements has been developed.

A new nanocomposite material based on gold nanorods and polyurethane foam was obtained, and a method for the determination of catecholamines with the use of this nanocomposite modified with silver nitrate was developed. The determination is based on the measuring hypsochromic shift of a short-wave surface plasmon resonance band in a diffuse reflection spectrum of the nanocomposite. This shift is caused by reduction of silver from silver ions on the surface of gold nanorods under the influence of catecholamines. Effects of time, pH, volume of the reaction mixture, concentration of silver ions, and catecholamines on the interaction were examined. The proposed method allows to determine dobutamine, epinephrine, norepinephrine and dopamine with the detection limits of 0.1, 0.07, 0.07, and 0.05 μg mL−1, respectively. The developed method can be applied to analysis of medicines.

Optical properties can be programmed on mesoscopic scales by patterning host materials while ordering their nanoparticle inclusions. While liquid crystals are often used to define the ordering of nanoparticles dispersed within them, this approach is typically limited to liquid crystals confined in classic geometries. In this work, the orientational order that liquid crystalline colloidal hosts impose on anisotropic nanoparticle inclusions is combined with an additive manufacturing method that enables engineered, macroscopic three-dimensional (3D) patterns of co-aligned gold nanorods and cellulose nanocrystals. These gels exhibit polarization-dependent plasmonic properties that emerge from the unique interaction between the host medium's anisotropic optical properties defined by orientationally ordered cellulose nanocrystals, from the liquid crystal's gold nanorod inclusions, and from the complexity of spatial patterns accessed with 3D printing. The gels' optical properties that are defined by the interplay of these effects are tuned by controlling the gels' order, which is tuned by adjusting the gels' cellulose nanocrystal concentrations. Lithe optical responsiveness of these composite gels to polarized radiation may enable unique technological applications like polarization-sensitive optical elements.

The article discusses the methods of constructing mathematical models describing the heat balance in the “hydraulic puller-drill shaft” node used in jet-grouting machines during high pressure transmission from stationary elements to rotating parts of the mechanism. The main heat fluxes, which include the heat flux in the hydraulic removal system; heat flow to the water-cement mixture, heat flow to the pre-compression mechanism, heat flow to the drill shaftand methods for solving the heat conduction equation for calculating the temperature field distribution that are formed during the operation of this structural unit are shown.Thus, the proposed modeling technique will allow us to consider and calculate the heat balance of the designed structural jet-grouting unit of ultrahigh pressure, as a set of heat fluxes generated during the operation of this device, considering it as heat sources, from which heat transfer occurs during the operation of the «hydraulic puller», a sealing element, which will ensure predictability of design characteristics of the device design and increase their efficiency. This approach makes it possible to more fully consider the existing main heat fluxes and more accurately simulate the heat balance as part of the assessment of the stress-strain state of ultra-high pressure jet-grouting devices.

Цель. Установить зависимости огнезащитной эффективности – времени достижения критической температуры 500 °С при стандартном огневом воздействии – от геометрических размеров и формы поперечного сечения и толщины огнезащиты из гипсовых плит Knauf Fireboard для вертикальных двутавров и труб стальных горячекатаных. Методы. Использование расчетных компьютерных моделей, взаимоувязанных с результатами огневых испытаний огнезащитной эффективности гипсовых плит Knauf Fireboard для вертикальных стальных профилей различного сортамента. Результаты. Разработаны трехмерные расчетные компьютерные модели для моделирования теплообмена с газовой средой пожара для поперечных сечений вертикальных стальных профилей, защищенных огнестойкими гипсовыми плитами Knauf Fireboard. Установлены зависимости эффективного коэффициента теплопроводности и объемной теплоемкости огнестойких гипсовых плит Knauf Fireboard от их толщины и температуры. Установлены зависимости огнезащитной эффективности – времени достижения критической температуры 500 °С при стандартном огневом воздействии – от геометрических размеров и формы поперечного сечения и толщины огнезащиты из гипсовых плит Knauf Fireboard для вертикальных двутавров и труб стальных горячекатаных. Установлено, что время прогрева стальных профилей с огнезащитой из гипсовых плит Knauf Fireboard зависит не только от приведенной толщины металла (коэффициента сечения), но и геометрических размеров и формы поперечного сечения. Область применения исследований. Результаты исследований могут быть использованы для оценки огнестойкости стальных конструкций с конструктивной огнезащитой из гипсовых плит Knauf Fireboard.

Purpose. To determine the actual values of the density, percentage of water, coefficients of thermal conductivity and heat capacity of centrifuged concrete during heating. Methods. Experimental determination of the density and percentage of water of samples from centrifuged concrete before and after heating. Theoretical studies of the coefficients of thermal conductivity and heat capacity on the basis of the data obtained. Findings. The dependences of the density of concrete on temperature and location in a centrifuged structure are obtained. Indirectly revealed the variability of humidity of concrete over the cross section of the centrifuged structure. For the functions of humidity over the cross section and density with increasing temperature, the values of the correction factors are obtained, which allow, depending on the properties of the centrifuged concrete structure of various thickness, as a whole, to determine these indicators at each point. Theoretically obtained values of the coefficients of thermal conductivity and specific heat capacity for centrifuged concrete. Application field of research. The research results can be used to solve the heat engineering problems of calculating the fire resistance of the above constructions.

Ce3+-doped Sr9Lu(PO4)7 polycrystalline material has been synthesized using a solid state reaction at high temperature. Luminescence spectroscopic properties and emission decay kinetics have been studied upon UV-VUV excitation. Emission from Ce 3+ ions located in two types of crystallographic sites has been identified in low-temperature spectra. Ce3+ ions have been shown to prefer occupying Sr2+ sites rather than Lu3+ sites. The temperature-dependent decay curves of Ce3+ 5d→4f emission demonstrate an excellent luminescence thermal stability.

The shift of the conduction band (CB) edge for thirty different (Lu,Gd) 3 (Ga,Al) 5 O 12 :Ce compositions, with simultaneous variation in Lu/Gd and Ga/Al content was studied using thermally stimulated luminescence (TSL). Specific TSL peaks were related to impurities of Ta, Cr, Yb, Ti and Eu in Lu 1 Gd 2 Ga 3 Al 2 O 12 :Ce ceramics. The shift of Yb-related peak positions (in temperature and trap depth) with composition modification was investigated as well. In Gd-containing (Lu,Gd) 3 (Ga,Al) 5 O 12 compositions a non-monotonous shift of the CB edge with increasing Ga content has been affirmed. The difference between thermal trap depths evaluated from our TSL experiments and optical trap depths obtained from the literature was explained by the role of lattice relaxation.

Background. Air heating in winter in the range of ambient temperatures below -5 °C may be carried out by the heat of the phase transition of water into ice. Heated air reduces energy consumption in ventilation systems, in heat pumps such as air–water and air–air, in boilers and furnaces for fuel combustion, during peak loads on heat supply systems, that reduces the installed capacity of heat-generating equipment and save energy. Objective. The aim of the study is experimental research and computer simulation of technology for producing ice pipes with internal and external fins by discrete thermal insulation for transverse and longitudinal ribs. Methods. Air with a temperature below -5 °C is passed through ice finned from the inside pipes immersed in water or irrigated with water, for use heated to -2-3 °C air in ventilation systems, heat pumps, fuel combustion systems and in buffer zones of buildings during frost. Experimental work on the production of finned ice pipes in the freezer and modeling in SolidWorks has been carried out. Results. The obtained ring interior edges are rounded due to the lateral flow of heat and provide an opportunity to obtain the coefficient of the fins of 1.3-2. When applying the individual elements of the longitudinal insulation, the pipe is obtained with an internal cross-section in the form of a polygon with the number of angles corresponding to the number of elements. External ribs could not be formed experimentally when applying internal thermal insulation elements due to the low heat exchange of the pipe with the air inside the vertical pipe placed in the freezer. In the simulation result in the forced supply of air into the inner tube of the two insulation elements arranged symmetrically, the oval cross-section tube of ice was received. Conclusions. The lower the ambient temperature, the greater the economic and energy effect. Ice finned tubes should be used for heating frosty air and cold storage, for example, to create ice decorative vases, in which containers with drinks of different shapes are placed. This is an element of novelty for the hotel and restaurant business.

Solid solution of Ca10.5–1.5xYbx(PO4)7 (0 ≤ x ≤ 1) was synthesized in the β-Са3(РО4)2-type structure by a standard solid-state method. Second-harmonic generation, differential scanning calorimetry, and dielectric measurements showed the presence of a reversible first-order phase transition of ferroelectric type between the room-temperature polar R3c structure to centrosymmetry. The temperature of the phase transition decreases from 1203 K for x = 0 to 788 K for x = 1, while the second-harmonic generation response decreases from 1.4 to 0.17 α-SiO2 powder standard units. The luminescence spectra of Ca10.5–1.5xYbx(PO4)7 point to two structural Yb3+ positions in full agreement with the structural data. The intensity of the luminescence emission line at ∼975 nm due to the 2F5/2 → 2F7/2 transition reaches the maximum at x = 0.667 in Ca10.5–1.5xYbx(PO4)7. The Yb3+ luminescence spectra studied as a function of the chemical composition 0

Halide-perovskite microlasers have demonstrated fascinating performance owing to their low-threshold lasing at room temperature and low-cost fabrication. However, being synthesized chemically, controllable fabrication of such microlasers remains challenging, and it requires template-assisted growth or complicated nanolithography. Here, we suggest and implement an approach for the fabrication of microlasers by direct laser ablation of a thin film on glass with donut-shaped femtosecond laser beams. The fabricated microlasers represent MAPbBrxIy microdisks with 760 nm thickness and diameters ranging from 2 to 9 μm that are controlled by a topological charge of the vortex beam. As a result, this method allows one to fabricate single-mode perovskite microlasers operating at room temperature in a broad spectral range (550–800 nm) with Q-factors up to 5500. High-speed fabrication and reproducibility of microdisk parameters, as well as a precise control of their location on a surface, make it possible to fabricat...

Novel red emitting phosphors Ca8MgSm1–х(PO4)7:xEu3+ with whitlockite-type structure were prepared by a high temperature solid-state reaction in air. Powder X-ray diffraction (PXRD), photoluminescence spectra, and fluorescence decay were used to characterize the structure and luminescence properties. All samples were found to have the expected rhombohedral structure with R 3 ¯ c space group. The non-polar space group is also confirmed by a photoluminescence study. This space group allows forbidden transitions for Eu3+. The presence of only one Shtark component in 5D0–7F0 confirms the presence of only one non-equivalent site containing Eu3+ ions. The high intensity of the transition ratio 5D0–7F2/5D0–7F1 establishes the strongly disordered environment of the Eu3+ ions. Thus, M1–M3 sites in the host matrix are occupied by Ca2+, Sm3+, and Eu3+ ions, whereas M5 is fully occupied by Mg2+. The optimal concentration was found with x = 0.75 in Ca8MgSm1–х(PO4)7:xEu3+ phosphors. The emitting of Sm3+ was depressed due to the high intensity of Eu3+ luminescence; however, the contribution of Sm3+ is manifested in the energy transfer process and shift of CIE coordinates. Furthermore, the CIE chromaticity coordinate of as-prepared Ca8MgSm0.25(PO4)7:0.75Eu3+ (x = 0.650; y = 0.345) is close to the standard red-emitting point (x = 0.67, y = 0.33). The experimental data indicate that Ca8MgSm1–х(PO4)7:xEu3+ upon excitation by near-UV radiation is a promising red phosphor for white-light-emitting diodes.

In this paper we show the advantages of transparent high conductive films based on filled single-wall carbon nanotubes. The nanotubes with internal channels filled with acceptor molecules (copper chloride or iodine) form networks demonstrating significantly improved characteristics. Due to the charge transfer between the nanotubes and filler, the doped-nanotube films exhibit a drop in electrical sheet resistance of an order of magnitude together with a noticeable increase of film transparency in the visible and near-infrared spectral range. The thermoelectric power measurements show a significant improvement of air-stability of the nanotube network in the course of the filling procedure. For the nanotube films with an initial transparency of 87% at 514 nm and electrical sheet resistance of 862 Ohm sq(-1) we observed an improvement of transparency up to 91% and a decrease of sheet resistance down to 98 Ohm sq(-1). The combination of the nanotube synthesis technique and molecules for encapsulation has been optimized for applications in optoelectronics.