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The paper presents a study of the formation of gas hydrate in a colloidal solution of water + SDS + SiO2. The effect of the kinetic promoter of sodium dodecyl sulfate (SDS) on the process of hydrate formation was studied at various concentrations: 0, 100, 300, 500 ppm at a constant SiO2 concentration of 500 ppm. A description of the experimental research methodology is given, the dependences of pressure and temperature changes on time for each SDS concentration are shown, and the coefficients of conversion of water and gas into the gas hydrate state are determined. The studies were carried out using carbon dioxide as a hydrate-forming gas.

The paper presents a experimental investigation of carbon dioxide hydrate formation in a colloidal solution of H2O+ SDS + SiO2 The influence of the kinetic promoter of sodium dodecyl sulfate (SDS) on the formation of carbon dioxide gas hydrate at various concentrations: 0, 100, 300, 500 ppm was assessed. The SiO2 concentration in the solution was constant and equal to 300 ppm. The change in solution temperature and pressure during the production of hydrate is shown for each SDS concentration. The values of convection of solution and gas into the gas hydrate state were determined.

In this work, arc discharge synthesis was carried out by sputtering electrodes of various compositions in a helium medium, as a result of which two types of materials containing carbon globules and graphene flakes were obtained. The synthesized materials were characterized with transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. The effect of the type and concentration of carbon nanoparticles and the type of surfactants on the stability of water-based nanofluids was studied with optical spectroscopy. For carbon globules and water, the mass concentrations of nanoparticles and sodium dodecyl sulfate were determined to obtain a nanofluid based on them stable for 1 month, which are 0.02% and 1%, respectively. It was shown that the use of neonol AF 9-12 at a concentration of 2% didn’t lead to the stabilization of carbon globules with a mass concentration of 0.02% in water. For graphene flakes, the mass concentrations of nanoparticles and stabilizers to obtain a water-based nanofluid stable for 1 month were: 0.02% graphene flakes and 1% SDS, as well as 0.02% graphene flakes and 2% neonol AF 9-12, respectively.

We report on the fabrication method that enables the development of transparent conductive metasurfaces capable of the resonant absorption of light in specific frequency bands. The approach is based on embedding linear sp-carbon chains and metallic nanoparticles in a porous matrix of titanium dioxide (TiO2). We develop a blading technique for the formation of a periodical grating of TiO2 microtubes at the macroscale. The method allowed us to maintain the periodicity of an array of microtubes with an accuracy of ±5%. Tuning the diameter of the tubes and the concentration of metallic nanoparticles, we achieved the regime of strong resonant absorption of the fabricated complex metasurface in the visible range. Computer simulations helped revealthe regime of TE/TM-polarized laser pumping that allowed for the most efficient transformation of light energy into electric current flow. In the studied structures, the sp-carbon clusters embedded inside transparent titanium dioxide tubes play the role of atomic wires. The interplay between efficient conductivity through carbon wires and the plasmon-enhanced absorption of light allows the design of photodiode structures based on periodical metasurfaces and characterized by highly selective optical sensitivity. [ABSTRACT FROM AUTHOR]

Shungite carbon (ShC) nanoparticles in the form of stable aqueous dispersions represent a promising solution for optical and biomedical applications. The dispersion is an interesting phenomenon from the point of view of stabilization of ShC nanoparticles and their structural constituents up to the basic structural unit, namely a graphene fragment. Herein, we used these aqueous dispersions with easily released structural components to study laser irradiation with various durations and obtain hybrids of ShC with Ag and Au nanoparticles. The main role in the stabilization of ShC nanoparticles belongs to the graphene fragments and their stacks, which display a considerable dipole moment. Newly prepared aqueous dispersions of ShC–metal hybrid nanoparticles retained the stability inherent in the original nanoparticles both of ShC and metals. Changes in the size distribution pattern of nanoparticles in dispersions upon ablation were studied by dynamic light scattering (DLS). Raman with UV-Vis spectroscopy methods were applied to trace structural changes in ShC upon the formation of hybrid nanoparticles. Films obtained by condensation of the dispersions on glass substrates display periodic structures, as was revealed by SEM microscopy. There, the conditions under which nanoparticles lose their ability to disperse in water and retain a graphene-like structure in a film were revealed. [ABSTRACT FROM AUTHOR]

Linear carbon-based materials such as polyyne and cumulene oligomers provide a versatile platform for nano-physics and engineering. Direct gap quasi-1D polyyne structures are promising for the observation of strong and unusual excitonic effects arising due to the two-dimensional quantum confinement. Recently, we reported on the observation of sharp exciton peaks in low temperature photoluminescence spectra of polyyne chains (Kutrovskaya S et al 2020 Nano Lett. 20 6502–9). Here, we analyze the time-resolved optical response of this system. We extend the non-local dielectric response theory to predict the exciton radiative lifetime dependence on the band-gap value and on the length of the chain. A good agreement between the experiment and the theory is achieved. [ABSTRACT FROM AUTHOR]

We stabilize monoatomic carbon chains in water by attaching them to gold nanoparticles (NPs) by means of the laser ablation process. Resulting nanoobjects represent pairs of NPs connected by multiple straight carbon chains of several nanometer lengths. If NPs at the opposite ends of a chain differ in size, the structure acquires a dipole moment due to the difference in work functions of the two NPs. We take advantage of the dipole polarisation of carbon chains for ordering them by the external electric field. We deposit them on a glass substrate by the sputtering method in the presence of static electric fields of magnitudes up to 105 V/m. The formation of one-dimensional carbyne quasi-crystals deposited on a substrate is evidenced by high-resolution TEM and X-ray diffraction measurements. The original kinetic model describing the dynamics of ballistically flowing nano-dipoles reproduces the experimental diagram of orientation of the deposited chains. [ABSTRACT FROM AUTHOR]

We report on the fabrication of fractal dendrites using laser-induced melting of aluminum alloys. We target boron carbide (B 4 C), which is one of the most effective radiation-absorbing materials characterized by a low coefficient of thermal expansion. Due to the high fragility of B 4 C crystals, we were able to introduce its nanoparticles into a stabilization aluminum matrix of AA385.0. The high-intensity laser field action led to the formation of composite dendrite structures under the effect of local surface melting. Modelling the dendrite cluster growth confirms its fractal nature and sheds light on the pattern behavior of the resulting quasicrystal structure. [ABSTRACT FROM AUTHOR]

The formation of macroscale carbon structures characterised by an sp-sp 2 -hybridization is realised by self-assembly in colloidal solutions under an effect of laser irradiation and electromagnetic fields. The sponge-like morphology, sculptured with gold nanoparticles (NPs) was revealed by Scanning Electron Microscopy (SEM) imaging. Full structural and defect characterization of the self-assembled sponges was provided using the micro-Raman spectroscopic technique. The synthesized clusters manifest themselves in the presence of a strong spectral band in the visible range of the photoluminescence spectra that is quite unusual for ordered sp 2 -carbon systems. [ABSTRACT FROM AUTHOR]