Dispersive Component Research Articles

Numerical study of the velocity distribution of the disperse component in the generation of a gas suspension flow by an electric field

This paper presents a self-consistent mathematical model of the dynamics of an electrically charged dusty medium. The carrier medium was described as a viscous, compressible and heat-conducting gas. The simulated flow is self-consistent, the parameters of each of the mixture components are determined by changing the parameters of other components. The mathematical model took into account intercomponent momentum exchange and heat transfer between the dispersed component of the mixture and the gas. The equations of the mathematical model are supplemented with boundary conditions. The mixture dynamics equations and the Poisson equation describing the electric field were solved by a numerical finite-difference method. The channel is divided into two parts, in one part of the channel there is a homogeneous gas, in the other part of the channel there is a gas containing electrically charged particles. Under the action of an electric field, the particles of the disperse component begin to move, and a gas flow is formed. This paper presents the results of calculations of the physical fields of an electrically charged dispersed suspension.

Impact of Galaxy Dynamics on Modified Gravity Constraints from Strong Lensing Systems

AbstractGalaxy-galaxy strong lensing systems have been used in literature to test General Relativity by constraining the post-Newtonian parameter (γPPN). Nevertheless, these methods are prone to systematic errors, some of which arise from difficulties in modelling the dynamics of the lens galaxy. In this study, we address the systematic error related to the assumption of a constant anisotropy between the radial and tangential components of the velocity dispersion of stars within the lens galaxy, characterised by the parameter β. We considered two radial models for the anisotropy parameter, the Osipkov-Merritt and Mamon & Lokas, as well three Gaussian priors for constant β. Our analysis showed that the choice of β has a strong impact on the value of γPPN, with radial models leading to lower values of this parameter.

Surface energetics of graphene oxide and reduced graphene oxide determined by inverse gas chromatographic technique at infinite dilution at room temperature.

Graphene is of great interest for many far-reaching applications that involve interparticle interactions in adsorbents, coatings, and composites. A deep understanding of the surface components has been crucial but achieving the most accurate and reliable values of these, unaffected by experimental conditions or the analytical techniques used, remains a major challenge. To this end, we have proposed in this paper a novel approach for the first time, to the best of our knowledge, to determine London dispersive and specific (polar) components including the Lewis acid-base character of the surface free energy of graphene materials (graphene oxide (GO), reduced graphene oxide (rGO), and graphite) using inverse gas chromatography (IGC) technique at an infinite dilution. We have estimated the London dispersive surface energy values of graphite, GO, and rGO as van der Waals interaction to be 156-179, 89-106, and 110-119mJm-2, respectively, in the temperature range of 320-360K. These are attributable to the surface properties impacted by the oxygen moieties, defects, and micropores on the carbon frameworks. Further, the acceptor (KA) and donor (KD) parameters of GO were found to be 0.71 and 0.96, respectively, while those of rGO were 0.54 and 1.05. Notably, the GO is more of the Lewis acid character that could be amphoteric, while the Lewis base characteristics of both GO and rGO are not significantly changed. These results provide foundational knowledge to understand the physicochemical properties of graphene surfaces, which should be helpful to designing interface engineering in various applications.

Multipolar Modeling of Spatially Dispersive Metasurfaces

There is today a growing need to accurately model the angular scattering response of metasurfaces for optical analog processing applications. However, the current metasurface modeling techniques are not well suited for such a task since they are limited to small angular spectrum transformations, as shall be demonstrated. The goal of this work is to overcome this limitation by improving the modeling accuracy of these techniques and, specifically, to provide a better description of the angular response of metasurfaces. This is achieved by extending the current methods, which are restricted to dipolar responses and weak spatially dispersive effects, so as to include quadrupolar responses and higher-order spatially dispersive components. The accuracy of the newly derived multipolar model is demonstrated by predicting the angular scattering of a dielectric metasurface. This results in a modeling accuracy that is at least two times better than the standard dipolar model.

Development of Water Repellent, Non-Friable Tannin-Furanic-Fatty Acids Biofoams.

Tannin-furanic foams were prepared with a good yield using the addition of relatively small proportions of a polyflavonoid tannin extract esterified with either palmitic acid, oleic acid, or lauric acid by its reaction with palmitoyl chloride, oleyl chloride, or lauryl chloride. FTIR analysis allowed us to ascertain the esterification of the tannin, and MALDI-TOF analysis allowed us to identify a number of multi-esterified flavonoid oligomers as well as some linked to residual carbohydrates related to the equally esterified tannin. These foams presented a markedly decreased surface friability or no friability at all, and at densities lower than the standard foam they were compared to. Equally, these experimental foams presented a much-improved water repellence, as indicated by their initial wetting angle, its small variation over time, and its stabilization at a high wetting angle value, while the wetting angle of the standard foam control went to zero very rapidly. This conclusion was supported by the calculation of the total surface energy of their surfaces as well as of their dispersive and polar components.

Study of concrete properties based on crushed stone sand mixture and fiber of fly ash of thermal power plants

Abstract The study aims to optimize the composition of the main composite, the components of which, in their joint presence, make it possible to obtain the most significant positive synergistic effect. The authors of this article used the fibers of fly ash from thermal power plants as a finely dispersed component added to the crushed stone sand mixture. The result of the study was a high-strength corrosion-resistant material consisting of a crushed stone sand mixture (CSSM) with the addition of the fibers of fly ash. The authors applied the thermogravimetric and standard methods to study and determine the performance and strength characteristics of the obtained material. The combined effect of a complex organic-mineral modifying additive and the cement with the fibers of fly ash provided a compacted and reinforced structure of cement stone. An optimal binder composition was developed, consisting of cement and fiber of fly ash. The authors of this article examined the physical-mechanical and structural-mechanical properties of a CSSM of fine-grained concrete reinforced with a complex additive of cement, fibers of fly ash, and a superplasticizer. The study also provided technological solutions for manufacturing a functional mixture of fine-grained concrete based on the developed complex organic-mineral additive.

Reduction of Sulphur in Marine Residual Fuels by Deasphalting to Produce VLSFO

This paper presents the results of the controlled sedimentation process for deasphalting, caused by targeted formation of the fuel dispersed system components incompatibility (proportion of the paraffins with normal structure increase) experimental investigations. The main purpose was to decrease the contained amount of sulphur in sedentary marine fuel and procure VLSFO. Developed and given account of the laboratorial method of instituting the sediment which modifies standard TSP and allows to control the deasphalting with the take-off of sediment and deasphaltisate for future analysis. In this case, 5 components of marine fuels, their basic physical and chemical properties, and chemical group composition were used as an object of study. Based on the data obtained and via use of worked out software package, 6 compositions of marine fuels were specified. Furthermore, they were then produced and their quality attributes were defined. The results show that the deasphalting caused by the components targeted incompatibility is accompanied by the desulphurization. Sulphur concentration took place in the sediment where its content was 4.5 times higher than in composite fuel. At the same time, sediment content fell from 0.9% to 1.02% by weight according to the fuel composition. The sulphur content in the resulting deasphaltisate declined by approximately 15% in relation to original fuel mix, moreover, other quality indicators improved. In order to find out whether the usage of sediment obtained is possible, its composition and structure were assessed. The results of the interpretation showed, that sediments were inclined to bitumens, which allows them to be mixed with sediments as a way to cut process waste. Targeted deasphalting makes it possible for the expenses on reducing sulphur containment in marine residual fuels to be decreased, which expands the opportunities of fuels application according to ISO 8217:2017.

Towards quantifying microbial dispersal in the environment.

Towards quantifying microbial dispersal in the environment.

Reduction smelting of ore-coal iron ore raw materials without carburization

Dedicated to grandfather and father Tleugabulov Suleiman Mustafievich and Tleugabulov Boris SuleimanovichWith the traditional method of processing cast iron into steel, a sufficiently large amount of finely dispersed iron-containing waste is formed at each stage, which represents secondary raw material resources. The use of them in small quantities as part of the agglomeration charge has no practical importance. Therefore, the development of technology for their mass metallurgical processing is a problematic task of a global scale. This present work is devoted to the solution of this problem. The processes of direct reduction of metals by solid carbon on the basis of new theoretical positions of dissociation-adsorption mechanism (DAM) open the way to effective processing of dispersed metal-containing industrial waste – converter and blast furnace sludge. Converter sludge represents a significant part of metal-containing industrial waste with a high concentration of iron. When organizing the process of charge preparation from the dispersed components of the charge (ore part and coal) and their uniform mixing, a developed contact surface is achieved. Unlike coke metallurgy, which is based on the preparation and use of a charge consisting of a lumped ore part and lump coke. When such a charge is loaded into the furnace, the chemical reaction between metal oxides and solid carbon is practically unable to proceed in a solid-phase state due to the limited contact surface between them. The pelletizing of a finely dispersed mixture will allow to obtain a mono-charge and to realize the process of reducing melting of the monocharge. In this work, the technology of one-stage reduction smelting of prepared ore-coal raw materials has been developed and proposed. At the same time, it is possible not only to dispose of the generated waste of metallurgical production (converter sludge), but also to recover the metal without its excessive carburization. In doing so, the final product of this processing scheme is naturally - alloyed steel without loss of valuable elements during the oxidation period.

Wetting thresholds for long-lasting superwettability: From intrinsic wetting boundary to critical roughness value

Fabricating superlyophilic and superlyophobic materials is of great significance in both academic research and practical application, but the boundary thresholds of intrinsic composition and surface roughness to achieve long-lasting superwettability are not completely understood yet. Herein, silicon nanowire (SiNW) surfaces are chosen as a model to study the intrinsic wetting boundary (IWB) and critical roughness value (CRV) of superwettability by adjusting intrinsic composition and surface roughness systematically. Taking account of the influence of surface polarity, we define a critical f value as the ratio of polar components of the surface to dispersive components. Different liquids correspond to different IWBs reflected critical f values, for water, the IWB reflected in f value is around 0.5. For surface structure determined CRV, roughness is defined as a ratio of actual area to projected area, and the CRV of SiNWs to reach superwettability is tested to be around 18 (corresponding to 1 μm SiNWs), which is the transition point of wetting behavior from Wenzel state to Cassie state. With these thresholds, long-lasting superhydrophilicity with superspreading behavior and superhydrophobicity with ultralow adhesion for contaminants are achieved, which provide significant guidance for designing functional interfaces related to practical applications such as solar cells, microfluidics and electrodes.

Regeneration of interfacial bonding force of waste carbon fibers by light: Process demonstration and atomic level analysis

Although interest in recycling carbon fibers is rapidly growing, practical applications of recycled carbon fibers (rCFs) are limited owing to their poor wettability and adhesion. Surface modification of CFs was achieved through intense pulsed light (IPL) irradiation, which functionalizes surface of rCFs. Surface energy, chemical composition, morphology, and interfacial shear strength (IFSS) of rCFs before and after IPL irradiation were investigated. The rCF IPL-irradiated at 1,200V improved both polar and dispersive components of surface energy, and the IFSS significantly increased by 2.93 times in relation to that of the pristine rCF and reached 95% of that of high-grade commercial CFs. We proposed a mechanism by which oxygen functional groups on the rCF surface enhance the molecular bonding force with HDPE, and the model was validated from molecular dynamics simulations. IPL irradiation is a rapid and effective surface treatment method that can be employed for the manufacture of rCF-reinforced composites.

Security-enhanced watermark embedding and transmission based on synchronized chaotic semiconductor lasers

In this paper, we propose and numerically demonstrate a chaotic watermarking encryption and secure transmission scheme based on two synchronized response lasers (RLs) subject to identical injection from a driving laser (DL). In this proposed system, the chaotic signal from DL can be optimized after passing through a phase modulator and a dispersion component, then the chaotic signal with large bandwidth and low time delay signature is obtained. Simultaneously injecting this chaotic signal into two identical RLs, high-quality chaos synchronization between two RLs can be realized. Both synchronized chaotic signals are, respectively, divided into two parts. One is used to generate shared keys required by the watermarking encryption, and the other is used as chaotic carrier to realize the secure message transmission. After introducing the synchronized optical chaos into the watermarking encryption algorithm, the normalized correlation of the extracted watermark without long-distance transmission is 0.9554 and can still maintain above 0.9 over 200 km transmission fiber. The message transmission and watermark extraction have good robustness to the fiber parameter mismatches, and excellent performances can be maintained even within 20% mismatches range. In our method, synchronized high-quality optical chaotic signals from two RLs are used to watermark embedding and transmission, and double encryption can be realized, which can open a new path for future high-speed and security-enhanced watermark embedding and transmission.

Fiber-Concentration Distributions of Pulp Suspension Flow behind a Partition Plate Inserted in a Channel as Applied to a Papermaking Machine

This study involved an experimental investigation of the distribution of pulp fiber concentration in the region behind a partition plate with a tapered trailing-edge inserted in a convergent channel. The channel was modeled at the laboratory scale for the dispersion and rectification components of the headbox passage in a papermaking machine. For the experiments, the inlet cross-sectional average flow velocity, USUBa/SUB, of an actual pulp suspension was in the range of 0.03-3.3 m/s. The flow was visualized, and the fiber-concentration distribution was measured. Subsequently, the effects of the flow velocity on the time-averaged and fluctuating fiber-concentration distributions (CSUBa/SUB and C’, respectively) in the flow direction were examined through comparisons with those in the cases where the plate was installed in the parallel channel or had a simple rectangular edge. In the convergent channel with the tapered trailing-edge, the fiber-concentration defect behind the plate was reduced abruptly. Moreover, the uniformity of the fiber-concentration distribution at the convergence exit did not vary with the flow velocity, thereby having a low value. Overall, the fundamental observations obtained in this study can contribute to the optimization and improvement of the headbox channels of papermaking machines.

Improved Estimates of Host-Guest Interaction Energies for Endohedral Fullerenes Containing Rare Gas Atoms, Small Molecules, and Cations.

Endohedral fullerenes have evinced much interest from the fundamental and applications points of view. However, given the nature of the weak interaction between the guest species and the host cage in these confined systems, the interaction energy values obtained using various theoretical methods, and different basis sets vary over a wide range. For example, the reported interaction energy for the HF@C60 system ranges from -2.5 kcal/mol to -14.9 kcal/mol. In the present manuscript, we report reliable interaction energy values for different endohedral fullerenes (He@C60 , Ne@C60 , Ar@C60 , Kr@C60 , H2 @C60 , HF@C60 , H2 O@C60 , NH3 @C60 , CH4 @C60 , Li+ @C60 , Na+ @C60 , and K+ @C60 ) obtained using the domain-based local pair natural orbital coupled-cluster singles, doubles, and perturbative triples (DLPNO-CCSD(T)) method and the def2-TZVP basis set. We believe that these energy values could be considered as benchmark values, and the performance of other quantum chemical methods could be assessed accordingly. Local energy decomposition analysis within the DLPNO-CCSD(T) framework is used to estimate the electrostatic, exchange, and dispersion components of the interaction energy for some of the endohedral fullerenes.

Powder cohesion and energy to break an avalanche: Can we address surface heterogeneity?

• The cohesion was related to the specific surface area. • The dispersive component of the surface energy (van der Waals forces) prevailed. • Surface heterogeneity results confirmed preferable drug-excipient interactions. • Alginic acid showed a better carrier effect than calcium alginate. • The W adh / W coh ratio near to unity confirmed stability of interactive mixtures.

CHARACTERISTICS OF MICROEXPLOSIVE DISPERSION OF GEL FUEL PARTICLES IGNITEDIN A HIGH-TEMPERATURE AIR MEDIUM

An experimental study of the characteristics of the processes occurring during the ignition and combustion of single particles (10 mg) of typical gel fuel in a high-temperature air environment was carried out using a software and hardware complex consisting of a high-speed video camera, LED spotlight. The group of fuel compositions is prepared on the basis of oil-filled cryogels without and with 30 %(wt.) addition of solid finely dispersed components (coal particles, Si, and Cu). Polyvinyl alcohol (PVA) was used as an organic polymer thickener (10 %(wt.) in an aqueous solution). Fuel compositions are characterized by microexplosive dispersion of particles under conditionsof intense heating. By varying air temperature in the range of 600-1000 ◦C, the velocities of movement of finefragments after microexplosive dispersion of a droplet of fuel melt were determined.

Quantitative Analysis of Adhesion Characteristics between Crumb Rubber Modified Asphalt and Aggregate Using Surface Free Energy Theory.

The utilization of waste rubber tires is of great value for environment protection and resource recovery, which can also improve the properties of matrix asphalt. The adhesion characteristics were evaluated for crumb rubber modified asphalt and limestone aggregate using the surface free energy (SFE) approach. Four types of matrix asphalt and four rubber contents were used to prepare the crumb rubber modified asphalt. The contact angle of matrix and crumb rubber modified asphalt was obtained, and the SFE indicators (dispersion, polar component, and compatibility rate—CR) were calculated. Moreover, the water stability tests were conducted using one matrix and rubber modified asphalt in order to investigate the relationship between SFE and water stability indicators. Results showed that the total SFE, dispersion component, adhesion work, and CR increased with the addition of crumb rubber, while the polar component and spalling work decreased. The types of asphalt had different influences on SFE indicators. The results from analysis of variation (ANOVA) indicated asphalt type and rubber content had significant influence on the adhesion work, spalling work and CR, and the influence of asphalt type was greater than that of rubber content. Additionally, the retained Marshall Stability and tensile strength ratio had better correlation with adhesion work and CR, but less with spalling work. The presented results demonstrated that the type of matrix asphalt played an important role in the adhesion characteristics for the crumb rubber modified asphalt.

МЕТОДИЧЕСКИЕ ОСОБЕННОСТИ ОПРЕДЕЛЕНИЯ УДЕЛЬНОЙ ПОВЕРХНОСТНОЙ ЭНЕРГИИ МИНЕРАЛЬНЫХ КВАРЦСОДЕРЖАЩИХ ПОРОШКОВ

Methods for sample preparation of prototypes for the subsequent determination of the specific surface energy by the Owens, Wendt, Rabel and Kaelble (OWRK) method are worked out on the example of highly dispersed powders of quartz sand, characterized by a SiO2 content of 98.3%. For this purpose, dry grinding in a planetary ball mill disperses the raw material, the mechanical activation time is varied in the range of 15÷45 min. Five fractions of highly dispersed powders are obtained. They are characterized by the specific surface area. This parameter is changed in the following range: 1200÷3000 kg/m2. Prototypes for subsequent research by the OWRK method are made by pressing with a pressing force of 2 to 16 tons. As a criterion for optimizing sample preparation conditions, the coefficient of determination of the functional dependence of the cosine of the wetting angle of the surface of test samples with working fluids (decane, glycerin, water) on the dispersion component of their surface tension is proposed. It has been established that for the quartz sand used, the maximum value of the coefficient of determination (0.94) is noted at a pressing force of fine fractions equal to two tons. An increase in the specific surface area of powder materials over 2370 kg/m2, obtained by mechanical dispersion and an increase in pressing force up to 12÷16 tons, leads to additional errors in determining the surface tension of compacted prototypes by the OWRK method.

The association between language-based task-functional magnetic resonance imaging hemodynamics and baseline GABA+ and glutamate-glutamine measured in pre-supplementary motor area: A pilot study in an aging model.

Aging is a natural phenomenon that elicits slow and progressive cerebrovascular and neurophysiological changes that eventually lead to cognitive decline. The objective of this pilot study is to examine the association of GABA+ and glutamate–glutamine (Glx) complex with language-based blood oxygen level dependent (BOLD) hemodynamics in an aging model. More specifically, using standard BOLD we will first attempt to validate whether previously reported findings for BOLD amplitude and resting neurochemical relationships hold in an aging model. Secondly, we will investigate how our recently established neurosensitized task-BOLD energetics relate to resting GABA+ and Glx, especially accounting for titration of task difficulty. To support the above endeavors, we optimize the baseline fitting for edited magnetic resonance spectroscopy (MRS) difference spectra to sensitize GABA+ and Glx concentrations to aging-related differences. We identify a spline-knot spacing of 0.6ppm to yield the optimal aging-related differences in GABA+ and Glx. The optimized MRS values were then graduated to relate to task-BOLD hemodynamics. Our results did not replicate previous findings that relate task-BOLD amplitude and resting GABA+ and Glx. However, we did identify neurochemistry relationships with the vascularly-driven dispersion component of the hemodynamic response function, specifically in older participants. In terms of neuro-sensitized BOLD energetics and the underlying role of GABA+ and Glx, our data suggests that the task demands are supported by both neurometabolites depending on the difficulty of the task stimuli. Another novelty is that we developed task-based functional parcellation of pre-SMA using both groups. In sum, we are the first to demonstrate that multimodal task-fMRI and MRS studies are beneficial to improve our understanding of the aging brain physiology, and to set the platform to better inform approaches for clinical care in aging-related neurovascular diseases. We also urge future studies to replicate our findings in a larger population incorporating a lifespan framework.

Experimental demonstration of synchronous privacy enhanced chaotic temporal phase en/decryption for high speed secure optical communication.

Protecting confidential high speed optical signal transmission at the lowest physical layer is a critical challenge for modern fiber-optic communication systems. In this paper, we experimentally demonstrate a novel synchronous privacy enhanced chaotic temporal phase en/decryption scheme for high-speed physical layer secure optical communication. A remote chaos synchronization architecture relying on common source signal driving and private response hardware modules comprising of dispersive components and slave lasers is employed to generate synchronized private chaotic en/decryption signals, and simultaneously suppress residual driving-response correlation for enhancing the security. A proof-of-principle demonstration by secure transmission of a 28 Gb/s on-off-keying modulated confidential signal over 100 km single mode fiber link based on the private chaotic temporal phase en/decryption scheme is successfully achieved. The demonstrated hardware optical en/decryption approach may provide a promising way towards future ultra-high speed physical layer secure optical communication systems.