Homogeneous Suspension Research Articles

Thermal Performance Analysis of a Nonlinear Couple Stress Ternary Hybrid Nanofluid in a Channel: A Fractal-Fractional Approach.

Nanofluids have improved thermophysical properties compared to conventional fluids, which makes them promising successors in fluid technology. The use of nanofluids enables optimal thermal efficiency to be achieved by introducing a minimal concentration of nanoparticles that are stably suspended in conventional fluids. The use of nanofluids in technology and industry is steadily increasing due to their effective implementation. The improved thermophysical properties of nanofluids have a significant impact on their effectiveness in convection phenomena. The technology is not yet complete at this point; binary and ternary nanofluids are currently being used to improve the performance of conventional fluids. Therefore, this work aims to theoretically investigate the ternary nanofluid flow of a couple stress fluid in a vertical channel. A homogeneous suspension of alumina, cuprous oxide, and titania nanoparticles is formed by dispersing trihybridized nanoparticles in a base fluid (water). The effects of pressure gradient and viscous dissipation are also considered in the analysis. The classical ternary nanofluid model with couple stress was generalized using the fractal-fractional derivative (FFD) operator. The Crank-Nicolson technique helped to discretize the generalized model, which was then solved using computer tools. To investigate the properties of the fluid flow and the distribution of thermal energy in the fluid, numerical methods were used to calculate the solution, which was then plotted as a function of various physical factors. The graphical results show that at a volume fraction of 0.04 (corresponding to 4% of the base fluid), the heat transfer rate of the ternary nanofluid flow increases significantly compared to the binary and unary nanofluid flows.

Carbon Nanotubes in Cement-A New Approach for Building Composites and Its Influence on Environmental Effect of Material.

An addition of carbon nanostructures to cement paste is problematic due to the difficulties in obtaining homogenous mixtures. The paper reports on a more effective way of mixing carboxylated multi-walled carbon nanotubes (MWCNT-COOH) in cement pastes. The additional biological impact of the studied nanomodified cement was analyzed in the case of two moss species' vitality. The applied approach of obtaining a homogeneous mixture is based on intense mechanochemical mixing of MWCNT-COOH together with polycarboxylate superplasticizer (SP). As a result, a more homogenous suspension of MWCNT-COOH within a liquid superplasticizer, suitable for addition to hydrophilic cement paste, was obtained. FT-IR/Raman spectroscopy was used for materials' characterization. To explain the mixing process at the molecular level, systematic theoretical studies using density functional theory (DFT) were performed. The structures, interaction energies and IR/Raman vibrational spectra of model carboxylic acids, mixed with functionalized SWCNTs as simplified models of real MWCNTs, were obtained. Due to the controversial opinions on the environmental hazards of carbon nanostructures, additional in vivo studies were performed. In this case, effects of cement modified by the addition of small amounts of MWCNT-COOH with SP in comparison to the composite without carbon nanostructures and control subsoil on the vitality of mosses Polytrichum formosum and Pseudoscleropodium purum were studied.

Sedimentation of short-lived fluid-solid suspensions

In this study, we propose a particle sedimentation/aggradation law for homogeneous concentrated suspensions. This law, valid in the Stokes flow regime, can be used to describe the sedimentation process observed in short-lived rapid flows, developed at high Reynolds numbers, that can be described as low-viscosity quasi-parallel flows traveling at constant velocity and that progressively sediment during the dominant phase of transport to leave a triangular or trapezoidal deposit of constant slope. The particle aggradation velocity can thus be predicted from the product of the mean flow velocity and the deposit slope and turns out to be roughly similar to that measured from static suspensions of the same concentration, provided that the flow Reynolds number, based on the mean flow velocity, the fluid properties, and the particle size, remains inferior to a few hundred, such as the mixture agitation cannot disturb the sedimentation process. These important results provide the possibility of describing the depositional dynamics during the final stage of extreme events, as well as to infer the mixture rheology, from physical parameters that can be easily measured in the field.

Durable Superhydrophobic Coatings with Attapulgite for Inhibiting 5G Radome Rain Attenuation.

5G radomes are easily wetted and stained by rainfall, which greatly reduces the quality of signal transmission. Superhydrophobic coatings are expected to solve this problem because of their unique wettability, but it is still challenging to develop robust superhydrophobic coatings via simple methods. Here, we report the design of robust superhydrophobic coatings containing oxalic acid-modified attapulgite (MDP) for inhibiting rain attenuation of 5G radomes. First, a homogeneous suspension was prepared by nonsolvent-induced phase separation of a silicone-modified polyester adhesive (SMPA) solution containing fluorinated MDP (F-MDP) nanorods. Superhydrophobic coatings can be easily prepared by spraying the suspension. The effects of phase separation and the SMPA/F-MDP ratio on the surface morphology, superhydrophobicity, and stability of the coatings were systematically investigated. The micro-/nanostructure and low surface energy endow the coatings with excellent static and dynamic superhydrophobicity. Compared with previous studies, the coatings exhibit excellent mechanical stability, flexibility, chemical stability, and pressure resistance due to the combined effects of adhesion by SMPA, self-similar micro-/nanostructures, reinforcement by the MDP nanorods, etc. Consequently, the coatings show good performance in preventing rain attenuation of 5G radomes, an emerging application of Superhydrophobic coatings. We believe that the coatings have great application potential in various fields, including 5G communication.

Advanced Electrospun Composites Based on Polycaprolactone Fibers Loaded with Micronized Tungsten Powders for Radiation Shielding.

Exposure to high levels of radiation can cause acute, long-term health effects, such as acute radiation syndrome, cancer, and cardiovascular disease. This is an important occupational hazard in different fields, such as the aerospace and healthcare industry, as well as a crucial burden to overcome to boost space applications and exploration. Protective bulky equipment made of heavy metals is not suitable for many advanced purporses, such as mobile devices, wearable shields, and manned spacecrafts. In the latter case, the in-space manufacturing of protective shields is highly desirable and remains an unmet need. Composites made of polymers and high atomic number fillers are potential means for radiation protection due to their low weight, good flexibility, and good processability. In the present work, we developed electrospun composites based on polycaprolactone (polymer matrix) and tungsten powder for application as shielding materials. Electrospinning is a versatile technology that is easily scalable at an industrial level and allows obtaining very lightweight, flexible sheet materials for wearables. By controlling tungsten powder size, we engineered homogeneous, stable and processable suspensions to fabricate radiation composite shielding sheets. The shielding capability was assessed by an in vivo model on prototype composite sheets containing 80 w% of W filler in a polycaprolactone (PCL) fibrous matrix by means of irradiation tests (X-rays) on mice. The obtained results are promising; as expected, the shielding effectivity of the developed composite material increases with the thickness/number of stacked layers. It is worth noting that a thin barrier consisting of 24 layers of the innovative shielding material reduces the extent of apoptosis by 1.5 times compared to the non-shielded mice.

The Optimal Parameter for Coating ZnO Nanoparticle on Orthodontic Molar Tube by Electrophoretic Deposition Method (An Invitro Study)

The fixed orthodontic appliance may enhance devious pathogens and increase biofilm accumulation around the orthodontic molar tube (OMT) surface, which may cause demineralization of the tooth surface. However, the stainless-steel OMT coated with ZnO nanoparticles may enhance antimicrobial efficacy and reduce biofilm accretion. The study aimed to identify the optimal parameter for coating orthodontic molar tubes with antimicrobial ZnO nanoparticles by the electrophoretic deposition (EPD)cell. 36 orthodontic molar tubes were included in this study. The coating process was carried out using an EPD cell. Various concentrations (7.5, 10, 20, 33) g/L of ZnO nanoparticles suspension were conducted in this study, in addition to multiple times and voltages. After the coating process, the samples were left to dry for 24 hours at room temperature. To confirm the coating and adhesion a qualitative tape test and the Scanning Electron microscope were used to study the morphological, topographical, and surface characteristics and the size of nanoparticles on the surface of the coated OMT. The innovative ZnO nanoparticles exhibit promising antibacterial properties against oral pathogens, leading to a decrease in plaque buildup, which may decrease tooth cavities and gingival irritation through orthodontic treatment. There was an increase in nanoparticle surface adhesion on the orthodontic molar tube surface at 2 mins deposition time while reduced surface adhesion as increased deposing time. The coating process was verified at a currency voltage of 30V, reducing nanoparticle agglomeration. A concentration of 10g/L of ZnO suspension shows the most stable and homogenous suspension.

Advancing Blood Flow in Stenotic Arteries through Magnetohydrodynamic Peristaltic Motion of Hybrid Nanoparticles

This research aims to investigate the efficacy of hybrid nanoparticles in improving magnetohydrodynamic (MHD) peristaltic blood flow in stenotic arteries. Hybrid nanoparticles combining MHD processes and peristaltic motion show promise for increasing blood flow through constricted arteries. To evaluate the impact of nanoparticles on blood flow parameters, researchers use theoretical modelling and analytical solutions. Incorporating copper and aluminium oxide nanoparticles (Cu-Al2O3) into blood, leading to the formation of an ionic solution, is a crucial step in creating a homogeneous hybrid blood suspension. The mathematical model uses approximations of the stenosis and non-dimensional parameters for a mild stenosis scenario to simplify the underlying coupled nonlinear partial differential equations. Analytical solutions for various blood flow parameters such as velocity, temperature, stream function, wall shear stress, Nusselt number, and flow resistance impedance are obtained using the perturbation technique. This study visually analyzes how different physiological variables affect arterial blood flow characteristics. The heat conductivity of blood is an essential aspect of preserving one's sustenance, which is largely determined by the concentration of hybrid nanoparticles. A streamlined pattern depicts the direction of blood flow within an artery. This research demonstrates that the adverse effects of vascular stenosis can be mitigated by using hybrid nanoparticles. In order to aid narrowed arteries, these nanoparticles lessen wall shear stress, boost axial flow speed, and enhance the velocity profile.

Flexible Cellulose Nanofiber (CNF)-Nano- Montmorillonite (MMT) Composite Sheet Structure and Water Vapor Barrier Performance

One of the newly developed nanomaterials for functioning as high-performance packaging materials to replace synthetic plastics such as low-density and high-density polyethylene (LDPE, HDPE) is cellulose nanofiber (CNF). These substances are biodegradable, recyclable, and renewable. While cellulose nanofiber-based films have substantially better water vapor permeability than traditional packaging polymers, they have extremely low oxygen permeability. Water vapor permeability (WVP) of the spray-coated composites was decreased via spraying nano-montmorillonite (MMT) content into CNF suspension and also high-pressure homogenization of CNF-MMT suspension. The process for spraying cellulose nanofiber (CNF)-nano-montmorillonite (MMT) suspension on the stainless-steel surface was developed to produce a high-barrier performance composite. The two types of composites were prepared via spraying of raw CNF with MMT and fibrillated CNF with MMT via high-pressure homogenization. The structure and barrier performance of these composites were investigated with SAXS and ASTM E96/E96M-05. Before homogenization, the MMT is agglomerated, while after homogenization it is more exfoliated, which is split up into individual sheets. The water vapor permeability could be reduced by adding up to 20 wt. % montmorillonite and dispersing montmorillonite with two passes in a high-pressure homogenizer. With montmorillonite addition above 20 wt. %, the water vapor permeability started to increase due to aggregation of the montmorillonite in the homogenized composite. At the optimal addition level, the best performance achieved with spraying was a water vapor permeability of 8.3 x 10-12 g/m.s.pa. The air permeability of the composite was evaluated to be less than 0.003 µm/Pa.s. This value confirms an impermeable composite for packaging applications. Considering the orientation of MMT in the composite, the composite’s structure can decide the barrier performance and can be altered by further fibrillation process of cellulose nanofibers via high-pressure homogenization.

A homogenous fluorescence immunoassay based on a DNA-grafted labeling strategy of magnetic microspheres for multiple neonicotinoids monitoring

Given the detrimental impact on non-target pollinators, there is a high demand for monitoring multiple neonicotinoid residues in the environment. In this study, we proposed a novel physical-biological coupled multiplexing system (PBCMS) to achieve a homogeneous and high-performance indirect competitive suspension array technology (ic-SAT) for multiple neonicotinoids monitoring. First, hapten-decorated microspheres (HDMs) were prepared by ligating the streptavidin-modified microspheres with the biotinylated hapten, according to a novel molecularly-defined single-stranded DNA (ssDNA)-grafted labeling approach. Taking thiamethoxam (THX) and imidacloprid (IMI) as models, the binding properties of two anti-neonicotinoid antibodies were profiled by establishing fluorescence monoplex ic-SAT assays. Subsequently, two HDMs (2.8 and 5.0 μm) immobilized with THX and IMI haptens were synthesized and then implemented to fabricate a dualplex ic-SAT assay, while they were distinguished via a facile diameter-resolved decoding process through flow cytometry. Excitingly, the screening capacity of the dualplex ic-SAT assay was significantly expanded by employing antibodies with distinctive binding profiles. It enables the simultaneous monitoring of 7 representative neonicotinoid insecticides (THX, IMI, acetamiprid, clothianidin, thiacloprid, nitenpyram and imidaclothiz) and 4 major metabolites in a single test sample, with IC50 values ranging from 0.02 to 572.70 ng/mL. Furthermore, the dualplex ic-SAT assay was applied to honey, pollen and bee samples, demonstrating satisfactory recovery rates (74.1 %∼106.3 %) and nice agreement with LC-MS/MS analysis. In summary, the PBCMS offers an easy-to-implement, robust and cost-effective way for establishing user-defined ic-SAT, providing a powerful analytical tool to simultaneously monitor multiple neonicotinoid residues in environmental samples.

Heat Transfer Application of Nanofluids and Testing of Thermal Conductivity

In response to the growing demand for more efficient heat transfer technologies in various industrial processes, the development of nanofluids has emerged as a promising solution. Traditional heat transfer fluids like mineral oil, ethylene glycol, and water have relatively low thermal conductivities compared to solids, limiting the compactness and efficiency of heat exchangers. Nanofluids, which are created by suspending ultrafine metallic or nonmetallic solid powders in base fluids, exhibit enhanced thermal properties due to the superior thermal conductivities of solid materials. This paper reviews the preparation, thermal conductivity measurement, and influencing factors of nanofluids, with a focus on thermal conductivity as the primary driver for improved heat transfer. The preparation of nanofluids involves either a one-step or two-step method, with the two-step method being more commonly used for oxide nanoparticles (NPs) such as Al2O3, ZnO, MgO, TiO2, and SiO2. The study discusses stabilization techniques like ultrasonication and magnetic force agitation to ensure homogeneous suspension and long-term stability of the nanofluids. The thermal conductivity measurements are conducted using short hot wire (SHW) and transient hot wire (THW) techniques, with considerations of the nonsteady-state nature and potential error sources. The research underscores the importance of rigorous experimental design and accurate data analysis to address the complexities and variability in thermal conductivity measurements, ultimately contributing to the advancement of nanofluid technologies for efficient heat transfer solutions.

Is Artemia susceptible to the microsporidium Ecytonucleospora hepatopenaei (EHP) infection?

Following the three-stage approach of the WOAH (World Organisation for Animal Health) standard on the confirmation of susceptible species to a specific pathogen, Artemia franciscana juveniles were challenged with immersion exposure (IM) in a homogenate suspension of Penaeus vannamei hepatopancreas infected with Ecytonucleospora hepatopenaei (EHP) and per os administration (PO) with chlorella soaked in EHP-infected hepatopancreatic homogenate suspension. Using TaqMan probe-based quantitative PCR, we detected that loads of EHP in A. franciscana juveniles from both the IM and PO groups were about 101 copies/ng-DNA on the 3rd day post-exposure (3 dpe). However, no more EHP was detectable in the challenged A. franciscana juveniles on 7 dpe. Nested PCR targeting the EHP spore wall protein gene did not produce a target band in A. franciscana juveniles on either 3 dpe or 7 dpe. The confirmative evidence of the absence of sustained infection with EHP in the exposed Artemia was substantiated using in situ DIG-labeling-loop-mediated DNA amplification (ISDL) on A. franciscana juvenile sections, which revealed a few weak grey-blue positive signals appeared on 3 dpe but disappeared on 7 dpe. The results indicated that exposure to EHP resulted in the invasion of Artemia in intestinal epithelial cells, but the infection was unable to persist, confirming Artemia is not susceptible to EHP. Therefore, the research countered the assertion of Artemia as a potential EHP reservoir.

Experimental and computational investigation of fluid flow and solid transport in split-and-recombine oscillatory flow reactors for organic chemistry in water

This study analyzes fluid dynamics and solid transport in split-and-recombine oscillatory flow reactors, to improve the understanding of the mechanisms behind the resuspension capacity of solids in flow driven by their efficacy in multiphase reactions. Based on its importance as a sustainable reaction medium, H2O was utilized as liquid phase. Experiments in the HANU 2X 5 flow reactor reveal a six-fold reduction in particle deposition under oscillatory flow with SiO2 slurries compared to constant flow. A DoE approach investigated the influence of oscillation parameters and flow rate, revealing the importance of tuning parameters to achieve homogeneous suspension. Quantitative transport up to 10 wt% SiO2 slurries was achieved. A computational fluid dynamics model revealed the presence of large recirculation and positive upward velocities near the static mixers under oscillatory flow, which facilitate particle resuspension, up to five times compared to stationary flow. Strategic asymmetries within the reactor enhance resuspension. Lagrangian particle tracing was implemented through an original procedure, allowing reduced computational time by 82%. The simulation validated the benefits of oscillations in sustaining particle suspension, explaining the mechanism that prevents deposition at the reactor bottom. The combination of experimental and computational approaches provides valuable insights for optimizing oscillatory flow reactor design.

Investigation of the homogeneity of particle suspension

The homogeneity of particle suspension has attracted more attention in the fields of rehydrating milk beverages. This work focus on size characterization of the floating, sticking (on the wall), suspended and settling particles involving both online and offline sizing techniques. Focused Beam Reflectance Measurement (FBRM) is a powerful online technique that is capable for measuring and analysing chord length distribution (CLD) of the suspended particles in liquid. It has been widely used in terms of monitoring size evolution of crystallization and sedimentation processes. In this work, a new approach that involves FBRM probe to measure the particle size distribution has been developed. The probe is placed at three different height levels in a standard container after one hour of free sedimentation. The results suggest that the finest fraction is dominant at all three heights but the percentage of it decreases with an increase of larger particles when looking at the bottom. Besides, all the floating, sticking and settling particles are collected and analysed, and the particle size distributions (PSDs) are obtained and compared using the offline sizing techniques, such as optical microscope and Camsizer. In the results, the suspended particle is the smallest one followed by the sticking and the floating particles, while the settling particle is the largest. However, for the sticking particles sticking on the wall, a great number of agglomerates is found during the test due to adhesion force, indicating that the size distribution might be overestimated. Based on the results, the target particle size range that can be stably suspended in the model suspension was selected by eliminating the unfavourable fractions.

Исследование гранулометрического состава измельченного продукта, полученого при измельчении доломита в центробежной мельнице вертикального типа

Introduction. Modern medium (10–200 microns) and fine (0.1–10.0 microns) powders have a high cost, which limits the scale of their production and use. This assumes the implementation the latest achievements in the field of creating new equipment that is not inferior in its technical characteristics to the best foreign models into industry. The use centrifugal mills of vertical type for grinding various raw materials has shown their high efficiency in obtaining materials in the range – 0.2–0.01 mm. Studies of these mills operation under various operating conditions made it possible to create a large data set on the dependence of the crushed material granulo-metric composition on the design features of the mills and technological parameters of the grinding process. The results of a previously study of the granulo-metric composition a finely dispersed crushed product integral distribution according to particle size classes less than 80 microns were presented. They were obtained in a Brookhaven BI-XDC X-ray analytical centrifuge by measuring particle sizes in natural sedimentation mode, when the centrifuge disk was stationary during the experiment. The studies of the particle size differential distribution of a finely dispersed crushed product according to particle size classes less than 80 microns, which have not been carried out to date are of particular interest. Purpose of the study. The differential distribution study of the finely dispersed granulo-metric product composition obtained by grinding lump dolomite in a centrifugal mills of vertical type under different operating modes. Materials and methods. To solve this problem, samples of crushed material were taken from grinding dolomite from the Bosninsky deposit (RNO-Alania) in a centrifugal mill of the vertical type MV-0.3 with a 300 mm rotor diameter with following technological modes of the grinding process: mill rotor speed n = 310; 360 min–1, height of the material column above the rotating rotor H = 180; 270 mm, test time – 6 hours. Selected samples with a size class of –0.08 mm were analyzed in an X-ray analytical centrifuge Brookhaven BI-XDC, designed to determine the particle size distribution in the range from 0.01 to 100 microns. The measurements were performed on a suspension prepared from a mixture of 0.5 g of the selected sample with a 20% solution of sucrose and distilled water. Samples with a size class of 0.08 mm were weighed on laboratory scales LV SP.005.048 RE. The resulting suspension was dispersed in an ultrasonic bath for 3–5 minutes. After dispersion, the suspension was poured into the analyzer disk. While stirring, the lower absorption baseline line of a homogeneous particle suspension was measured. The obtained data from the analysis of the fine fractions size of were processed by the centrifuge computer software and graphs of the differential distribution of particles were constructed for various technological modes of grinding dolomite in a centrifugal mill. During the processing of the experiments, minor bursts in the concentration of the crushed product were not taken into account. The results and discussion. For the first time, a differential analysis of the granulo-metric composition of finely dispersed material with a particle size of –0.08 mm, obtained by grinding lump dolomite in a centrifugal mill of the vertical type under different mill operating modes, was carried out. Under all investigated operating modes of the centrifugal mill, the main part of the fine fraction in the mill outlet was in the range from 1.197 to 4.643 μm, and in steady-state operation it varied from 1.310 to 4.601 μm. The range of fine particle sizes has maximum values when the height of the column of crushed material above the rotating mill rotor and the rotation speed of the mill rotor decrease, and minimum values are observed when the height of the column of crushed material above the rotating mill rotor increases and the rotation speed of the mill rotor increases. Resume. 1. The article presents the results of the granulo-metric composition differential distribution study of a finely dispersed product obtained by grinding lump dolomite in a centrifugal mill of the vertical type. 2. The conducted studies have shown that, despite the positive results in obtaining fine particles with a size of 0.001 microns (nanoparticles) by mechanical means, the industrial production of nano-materials when grinding lump mineral raw materials in a vertical centrifugal mill is not economically profitable due to the low specific productivity and high energy intensity of the grinding process. 3. The obtained research results can be useful in the design of centrifugal mills.

Controllable preparation of black phosphorus nanomaterials via liquid-phase pulsed discharge

The N, N-dimethylformamide (DMF) organic solvent was deliberately chosen as the optimal medium for this investigation. To achieve uniform dispersion of black phosphorus powder, which was obtained via shock-induced phase transformation, it was effectively dispersed in the DMF solution, resulting in a homogeneous black phosphorus-DMF suspension. Subsequently, a liquid-phase pulsed discharge experiment was conducted. This experimental setup harnessed the shockwave and tensile stripping effects generated by the rapid expansion of plasma during the liquid-phase pulsed discharge. These phenomena facilitated the interlayer exfoliation and dispersion of black phosphorus molecules, ultimately leading to the formation of a suspension containing black phosphorus quantum dots. In-depth investigation into the formation mechanism of black phosphorus quantum dots was also undertaken. Our findings reveal a pivotal influence of the charging voltage on the microstructure of the recovered samples. Specifically, as the charging voltage increases, the lateral dimensions of the retrieved two-dimensional black phosphorus powder undergo a remarkable reduction, transitioning from the micron-scale to less than 10 nm. The above results, which stem from meticulous experimentation and analysis, emphasize the significance of controlled synthesis in producing black phosphorus quantum dots with varying microstructures. Such insights hold substantial promise for advancing the field of materials science and enhancing the applicability of black phosphorus quantum dots in diverse applications.

Immediate and long-term consequences of the treatment of cholelithiasis by laparoscopic cholecystolithoextraction

The use of organ-preserving interventions for cholelithiasis is not widely used in modern medicine, although there are publications in the literature about the implementation of such interventions in some clinics. In the period 2004-2006 in the Republican Center for Functional Surgical Gastroenterology (Krasnodar), 12 surgical interventions were performed for cholelithiasis with preservation of the gallbladder (laparoscopic cholecystolithoextraction). From 2009 to 2011 the patients were called and examined (the first follow-up examination, on average 2.2 years after the operation). There were no signs of recurrence in 9 operated patients (of which 4 had an echogenic homogeneous suspension), in 3 patients a recurrence of stone formation was detected. Due to the reorganization and subsequent closure of the center, communication with patients was terminated. In 2023 (on average 15.5 years after surgery), patients who did not have a relapse at the first follow-up examination were examined. It was found that 3 out of 9 patients had no gallbladder stones, 3 patients underwent laparoscopic cholecystectomy due to relapse after the first follow-up examination, with 3 patients the relationship could not be established. The results of laparoscopic cholecystolithoextraction were analyzed depending on the clinical situation.

The Thermophysical Aspects of the Transformation of Porous Structures in Versatile Nanostructured Materials

The technology of obtaining porous nanostructures is based on ecological organosilicon materials and their uses in some spheres of human life, for example, for medical preparations, for thermal insulation of building structures and industrial equipment, and for cleaning. The purpose of this study was to establish correlations between various experimental parameters (shear stress, speed pulsations, temperature, viscosity, and processing time) and the rheological characteristics of suspensions obtained by the method of liquid-phase dispersion; it was a study of hydrodynamic effects and the processes of heat and mass exchange in liquid systems during the liquid-phase dispersion of hydrogel monoliths by means of discrete-pulse activation in a special rotary apparatus. The dehydration of hydrogels was carried out by two methods: convective drying in a layer and spraying in the coolant flow. Experiments have shown that the key parameters for obtaining stable homogeneous suspensions are a synergistic combination of concentration factors and processing time. To obtain adsorbents in the form of pastes with specified adsorption properties and a monolith size of up to 300 μm, the optimal parameters were a hydrogel concentration of 70% and a processing time in the double-recirculation mode. Xerogels obtained by convective drying are a polydisperse mixture of strong monoliths and fragile aggregates. In contrast, xerogel monoliths obtained by spray drying show great homogeneity in terms of dispersion and strength characteristics. The rheological parameters of the hydrogel dispersions, which depend on the concentration and hydrodynamic treatment modes, are the dominant factors affecting the moisture extraction during drying. This study marks the first investigation into the resilience of porous organosilicon structures against the influence of intense turbulence fields and mechanical stresses experienced within the rotor apparatus during suspension production.

Affine homogeneous varieties and suspensions

Affine homogeneous varieties and suspensions

Well-established carbon nanomaterials: modification, characterization and dispersion in different solvents

Three different types of carbon nanomaterials, SWCNTs, MWCNTs and GNPs were prepared, modified, characterized, and their dispersibility behavior in three different solvents was evaluated. The carbon nanotubes were synthesized by using the well-known chemical vapor deposition method and the graphene nanoplatelets by wet physicochemical treatment techniques. Their characterization was accomplished by using various advanced techniques, such as powder X-ray diffraction and Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and N2 adsorption at 77 K. Furthermore, the carbon nanostructures were modified via plasma treatment and wet chemical surface modification in order to enhance their dispersion characteristics, for achieving more homogenous suspensions and therefore to be remained dispersed over a reasonable period of time without any sedimentation. The effect of treatment parameters and the use of different solvents were thoroughly studied mainly by optical methods, but also by using the DIN/EN classified ISO method of oil absorption and UV–Vis spectroscopy. The enhanced dispersion rate is observed in both CNTs and GNPs materials following their surface treatment, especially when using the solvent n-methyl-2-pyrrolidone. The aforementioned studied nanomaterials are perfect candidate fillers for preparing polymeric mixed matrix membranes.Graphical abstract

Expanded graphite nanoparticles-based eutectic phase change materials for enhancement of thermal efficiency of pin–fin heat sink arrangement

This experimental work foresights the synthesis and characterization of the expanded graphite (EG) enhanced organic-organic eutectic PCM (EGePCM) with different weight percentages of the EG (ϕ = 1–5 %). In particular, the expanded graphite nanoparticles were exfoliated from the graphite flakes by acid protonation followed by extraction from the traditional co-precipitation synthesis. A series of EGePCM nanocomposites were fabricated through the homogeneous suspension of EG nanoparticles in the eutectic mixture (1:1) of organic PCM. The surface texture, physical morphology and chemical interaction of individual elements present inside the nanocomposites were thoroughly examined by FTIR, XRD, SEM, and FESEM. Conversely, the physical attributes, thermal stability, thermal degradation, and charging-discharging performance were also investigated. The EGePCM nanocomposite with 3 wt% of EG nanoparticles expresses a favourable increase of thermal conductivity by 232.24 %, with a nominal reduction in the latent heat storage capacity (176.5 J/g) of the PCM. In conjunction with the thermal attribute intensification, the incorporation of EG in nanocomposite reduces the supercooling degree to 9.16 °C with a phase change enthalpy of 174.8 J/g in cooling and 176.5 J/g in heating stage for 3 wt% of EG. A comprehensive experimental methodology was employed to investigate the thermal enactment features of different EGePCM nanocomposites inside a regular pin–fin arrangement imperilled with steady-state heat transfer. The effectiveness of the cooling rate was also encompassed under a variable range of heat flux (1.6–3.2 KW/m2) and EGePCM mixture (ϕ = 1–5 %). The heat transfer effectiveness was optimal at a mass fraction of 5 wt%, resulting in a 30 °C base temperature drop of the heat sink and a decrease in the charging-discharging duration of the nano PCM composite. This observation suggests an improvement in the thermal conductivity of the system with an incorporation of high thermal conductive EG nanoparticles. The enhanced thermal performance and notable thermal, physical and chemical stability facilitate the phase transition progression and render it highly advantageous for electronic or micro-electronic thermal cooling applications.