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The objective of this study was to characterize the performance of waste engine oil (WEO) and microwave-treated crumb rubber (CR)-modified asphalt (WEO-MCRA) and analyze the modification mechanism. The viscosity and dynamic shear rheological (DSR) tests were carried out to evaluate the viscoelasticity property of WEO-MCRA. The storage stability and fluorescence microscope (FM) tests were used to characterize the compatibility of the components. The Fourier transform infrared spectroscopy (FTIR) and molecular dynamic simulation were introduced to analyze the change of function groups and modification mechanism. The results demonstrated that introducing Wt.20% CR treated with microwave and Wt.6% WEO obtained a lower viscosity, excellent storage stability, and satisfactory elasticity properties of asphalt. The morphology of modifiers presented a thread-like structure microscopic with the range of WEO content Wt.3%–Wt.6%. Molecular dynamic simulations revealed that the aromatic may be intensively absorbed by CR and increase the likelihood of phase separation. WEO reduced the binding energy of CR to aromatic from 178.0 to 151.5 kcal/mol, which will contribute to the disaggregation of CR clusters. The diffusion coefficient shows a more obvious decrease with the addition of WEO and microwave treatment, which will benefit the stability of the asphalt. This study can provide a reference for the recycling of CR and WEO. [ABSTRACT FROM AUTHOR]

The effect of glycol derivatives including ethylene glycol (EG), diethylene glycol (DEG), and triethylene glycol (TEG) has been investigated on the characterization Al2O3 coating of anodized 7075-T6 aluminum in 20% w/w sulfuric acid, current density 4 A/dm2, and time 50 min. The thickness and hardness of Al2O3 layer measured and characterized by X-ray diffraction patterns, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The Tafle plots of linear polarization method and electrochemical impedance spectroscopy technique used to investigate the resistance to corrosion Al2O3 layer. The results showed that the thickness, hardness, and resistance to corrosion of Al2O3 film are increased, respectively, 30, 42, and 40% in the presence of glycols (10% w/w). The ratio of dielectric constant (ε) to dynamic viscosity (η) of TEG, DEG, and EG, respectively, is 0.48, 0.89, and 2.28 that is due to improvement of anodized aluminum in the presence glycol derivatives as EG > DEG > TEG. [ABSTRACT FROM AUTHOR]

Hybrid nanofluids are emerging as a new generation fluids because of their enhanced heat transport properties. In this work, thermal transport properties were investigated for TiO2/CuO hybrid nanofluids. Morphological characteristics were studied using SEM (Scanning Electron Microscopy). Elemental composition and average crystallite size were determined using XRD (X-ray Diffraction) and EDX (Energy Dispersive Spectroscopy). Hybrid nanofluids were produced by suspending TiO2/CuO nano powder of 1–50 nm into the water. Three different concentrations (0.01%, 0.03% and 0.05%) of the hybrid nanofluids were prepared. Thermal transport properties like density, viscosity, specific heat and thermal conductivity were assessed experimentally. The results depict that the thermal conductivity was enhanced by 65.8% in contrast to the base fluid at a volume concentration of 0.05%. Density, as well as dynamic viscosity, of TiO2/CuO hybrid nanofluids at 0.05% concentration is increased and specific heat is decreased with the increase in volume concentration. [ABSTRACT FROM AUTHOR]

The authors investigate the structural and colloid properties of a collector represented by amine hydrochloride treated by ultrasound and included in sylvinite flotation. Using the viscosity–temperature dependences, the Gibbs free energy is calculated for amine hydrochloride with and without treatment by ultrasound. It is found that ultrasound-treated amine added in salt-fat solutions are more stable to coagulation. From the synchronous thermal analysis, IR spectroscopy and X-ray phase analysis, it is inferred that ultrasonic treatment of amine hydrochloride slightly increases crystallinity of amine. The research findings improve understanding of the ultrasound effect on the change in the structural and colloid properties of the collector, which are important to optimizing output, sustainability and efficiency of potassium chloride production by flotation. [ABSTRACT FROM AUTHOR]

In this paper, the thermal oxygen aging test was conducted on the styrene-butadiene-styrene block copolymer (SBS) type high viscosity modifier (HVM), and the appearance, solubility, functional groups, and molecular weight changes were analyzed. The penetration, ductility, softening point, viscosity, high and low temperature performances, fatigue resistance, functional groups, molecular weight, and microscopic morphology changes of base asphalt and high viscosity asphalt (HVA) after thermal oxygen aging were tested. For the original and aged HVA, the diffusion of water or oxygen into HVA and the interface interaction between aggregate and HVA were studied by molecular dynamics simulation. Results show that the influence of temperature on the HVM aging is much greater than that of time. As the HVA aging degree deepens, the penetration and ductility decrease, the softening point and complex modulus increase, and the low-temperature performance and fatigue resistance deteriorates. The degradation of SBS component and the aging of asphalt component in HVA dominate in short-term and long-term aging, respectively. Therefore, the 60°C dynamic viscosity and 170°C Brookfield viscosity of HVA decrease first and then increase, while the phase angle increases first and then decreases. The SBS component and asphalt component in HVA mutually delays the aging. The van der Waals force plays a dominant role in the original or aged HVA-aggregate interface adhesion compared with the Coulomb force. With the HVA aging deepening or water addition, the absolute value of the interface interaction energy decreases, which reflects the adhesion weakening. Aging increases the free volume in HVA, exacerbating the diffusion of oxygen and water molecules into HVA. In the HVA–water–aggregate system, the asphalt-aggregate hydrogen bonds only account for less than 2% in different hydrogen bonds. As the HVA aging deepens, the water–asphalt hydrogen bond proportion increases, which weakens the water stripping resistance of the interface. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to compare the dynamic viscosity and steady viscosity characteristics of high-viscosity modified asphalt binder (HVA) and to analyze the applicability of the Cox–Merz rule as well as of the different zero shear viscosity (ZSV) test methods for HVA. To this end, seven kinds of asphalt binders including base asphalt binder, traditional modified asphalt binder with 4.5% styrene-butadiene-styrene (SBS), commercial HVA, and four self-shearing HVAs were prepared. The frequency sweep test and shear rate sweep test were conducted to obtain dynamic viscosity and steady viscosity, and the Cross model, Carreau model, and Carreau–Yasuda model were used to calculate ZSV based on these two types of viscosity. The results show that both the dynamic and steady viscosity tests prove that asphalt binder exhibits shear-thinning and yield stress behavior. Besides, there is a critical shear rate in the shear rate sweep test and the critical shear rate decreases with the increase of modifier content. The empirical Cox–Merz rule has good applicability in the Newtonian plateau region of base asphalt binder, but it is only applicable to a partial shear-thinning range of modified asphalt binder. Noteworthily, it fails when applied to HVA-C. The frequency sweep test is only suitable for determining the ZSV of base asphalt binder but not applicable at all to the modified asphalt binder because there is no Newtonian plateau in the dynamic viscosity, and the fitting results based on model extrapolation have huge errors as well as vary with the number of iterations. However, the shear rate sweep test is suitable for testing ZSV for both base and modified asphalt binders. Furthermore, it should be pointed out that ZSV obtained by model fitting is not a steady viscosity at zero shear rate but a Newtonian viscosity at a low shear rate, so low shear viscosity (LSV) is a more accurate concept. [ABSTRACT FROM AUTHOR]

The behavior of the velocity and shear stresses in two-phase laminar stratified flow near a triple point (TP), formed in the flow cross-section by the intersection of the interface with the conduit wall, is reconsidered. Differently from the no-slip boundary condition that showed a possibility of diverging shear stresses upon approaching the TP, we allow a slip of the fluids at the wall that can be prominent in the TP region. The Navier's boundary condition is used, which considers a linear relationship between the slip velocity and the strain rate component perpendicular to the surface. The solution for the velocity field in the TP region is obtained in terms of a power series of the distance from the TP having a discrete set of powers. Similarly to the solution obtained with no-slip B.C., a so-called 'characteristic equation' is obtained. Its solution yields a discrete set of non-integer powers that are dependent on the dynamic viscosity ratio and the contact angle. However, contrary to the no-slip solution, with Navier's B.C, each of these powers introduces a tower of terms resulting from the relation between the slip velocity and the velocity derivative at the wall. In addition, the solution also includes a tower of integer powers. The solution yields the velocity and the shear stress fields, as well as the flux of the force per length that acts on an arbitrary surface in the flow field. The latter is obtained by considering an equivalent 2D representation of the stress tensor. These are examined in comparison to the corresponding results obtained when no-slip at the wall is imposed. The relaxation of the wall shear stresses in cases where the no-slip condition predicts diverging wall shear stresses at the TP is demonstrated. It is shown that if the local velocity in the TP region is a limit of a global no-slip solution, the scaled velocity field in the TP region is independent of the details of the global flow field. • Two-phase stratified axial flow near the wall-interface junction (Triple Point, TP). • Removal of wall shear singularity in the TP region by allowing axial wall slip. • Navier's boundary condition is imposed on the wall in the TP region. • An analytical solution for the local flow field is obtained. • The local solution is independent of the global two-phase flow field details. [ABSTRACT FROM AUTHOR]

Infections of agricultural crops caused by pathogen ic fungi are among the most widespread and harmful, as they not only reduce the quantity of the harvest but also significantly deteriorate its quality. This study aims to develop unique seed-coating formulations incorporating biopolymers (polyhydroxyalkanoate and pullulan) and beneficial microorganisms for plant protection against phytopathogens. A microbial association of biocompatible endophytic bacteria has been created, including Pseudomonas flavescens D5, Bacillus aerophilus A2, Serratia proteamaculans B5, and Pseudomonas putida D7. These strains exhibited agronomically valuable properties: synthesis of the phytohormone IAA (from 45.2 to 69.2 µg mL−1), antagonistic activity against Fusarium oxysporum and Fusarium solani (growth inhibition zones from 1.8 to 3.0 cm), halotolerance (5–15% NaCl), and PHA production (2.77–4.54 g L−1). A pullulan synthesized by Aureobasidium pullulans C7 showed a low viscosity rate (from 395 Pa·s to 598 Pa·s) depending on the concentration of polysaccharide solutions. Therefore, at 8.0%, w/v concentration, viscosity virtually remained unchanged with increasing shear rate, indicating that it exhibits Newtonian flow behavior. The effectiveness of various antifungal seed coating formulations has been demonstrated to enhance the tolerance of barley plants to phytopathogens. [ABSTRACT FROM AUTHOR]

The mathematical formulation of the flowing liquid stream around and through confined multiply connected domains brings a complex differential system. Due to this, one cannot provide a complete description of flow field properties. The current pagination provides a numerical remedy by the use of artificial intelligence in this direction. To be more precise, fluid is considered in the rectangular channel. The circular, square, and triangular-shaped cylinders are positioned as an obstacle to the continuous fluid. The channel's left wall is viewed as an inlet and two different velocity profiles are introduced at an inlet that are constant and parabolic profile. To discretize the computational domain, hybrid meshing is used. The variance in basic variables, namely, the velocity of the liquid and the distribution of the liquid pressure, is recorded via graphs. The nine different meshed grades are tested for the drag and lift coefficients around the right-angle triangle, square, and circular barrier. The neural networking model is constructed by using 99 datasets of sample values for drag coefficient when characteristic length, the density of fluid, the dynamic viscosity of the fluid, and mean flow velocity are taken as inputs. The training of the neural network takes up 69 slots (about 70%), while the testing and validation of the neural network each take up 15 slots (15%). The Levenberg–Marquardt backpropagation algorithm is used for training. We have observed that for the parabolic profile, the drag coefficient is higher in intensity for each obstacle compared to the constant profile, while the lift coefficient shows opposite patterns. [ABSTRACT FROM AUTHOR]

Carbonate esters are used as additives in biodiesel to improve its thermophysical properties for better applicability. In this work, the experimental densities, dynamic viscosities and refractive indices for binary mixtures of dimethyl carbonate and four fatty acid esters (methyl decanoate, ethyl decanoate, methyl laurate, ethyl laurate) have been measured and presented over the complete concentration range at temperatures range from 293.15 to 323.15 K under normal pressure. The excess molar volumes and the viscosity deviations of the four binary mixtures were calculated with the measured data and correlated with the Redlich-Kister equation. The excess Gibbs energy of activation was also calculated. From the values of excess properties of the binary mixtures and its deviations indicate that the changes of molecular interactions in the mixtures. The experimental results could be useful for the study of biodiesel-carbonate blended fuels. [ABSTRACT FROM AUTHOR]

The present study describes the synthesis and characterization of TiO2 nanoparticles, TiO2 conjugated composites with Multi Walled Carbon Nanotube (MWCNT), Sodium Dodecyl-Sulfate (SDS), and Cetyltrimethylammonium Bromide (CTAB) and its effect on engine oil viscosity. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), and (UV-VIS) spectroscopy were used to characterize the synthesized nanomaterials. Prepared nanoparticles were mixed with 50 ml of 15W40 engine lubricant oil. The ultra-sonication instrument was used for even dispersion of the nanoparticles with the engine oil. The intent was to determine the influence of nanoparticles on viscosity characterization of oil at different temperature. The dynamic and kinematic viscosity of various combinations of suspended nanoparticle-lubricant combinations is measured using a redwood viscometer at three temperatures (34 °C, 44 °C, and 54 °C). Test revealed the following important observation: Bare TiO2 nano particles increased the viscosity of base oil, while TiO2 treated with CTAB, SDS and MWCNT decreased the viscosity of base oil up to 27% in cases considered. [ABSTRACT FROM AUTHOR]

In a gear transmission system in a closed space, the heat transfer between gears and fluids presents highly nonlinear characteristics due to the complex physical processes involved in heat exchange and fluid motion, and constructing and solving the thermodynamic model of the gearbox becomes a task that involves considerable difficulty. This paper takes a conical–cylindrical two-stage gearbox as the research object, proposes a fluid–solid coupled dynamics model based on the lattice Boltzmann (LBM) combined with the large eddy simulation (LES) method, and the adopted lattice model is the D3Q27 velocity model, which is used to numerically simulate the distribution of the flow field inside the gearbox and undertake in-depth research on the fluid motion law of the complex gear transmission system in the enclosed space. The model is solved to reveal the laws determining the gear speed and the effects of the lubricant's dynamic viscosity and thermal conductivity coefficient on the gear heat dissipation efficiency. By adopting the lattice Boltzmann method, we can simulate the fluid flow and heat transfer inside the gearbox more efficiently, which provides a new way to closely understand the thermodynamic behavior of closed complex gear transmission systems. The application of this method is expected to provide strong support for thermal performance optimization and the design of gear transmission systems. [ABSTRACT FROM AUTHOR]

Relevance. A promising fuel from an environmental point of view is coal-water suspensions. Multiple studies have shown that when they are burned, emissions of anthropogenic gases into the Earth's atmosphere are significantly reduced compared to emissions from coal burning. But the large-scale introduction of coal-water suspensions into the overall balance of energy production is difficult due to a significant delay in their ignition, which can reach several tens of seconds at relatively low oxidizer temperatures (Tg≤1073 K). One of the possible ways to solve this problem is the use of new technologies for preparation for combustion, for example, the use of additional microwave heating of fuel and the introduction of special additives into the composition of coal-water suspensions, which accelerate their ignition. The introduction of such additives into the fuel composition can lead to a significant change in the rheological characteristics. Aim. To determine the degree of impact of the concentration and type of wood additive in the composition of the coal-water suspension on the rheological characteristics of droplets of coal-water fuel, as well as the possibility of reducing the duration of thermal preparation of the latter when exposed to microwave heating. Object. Water-coal suspension based on long-flame thermal coal and on long-flame thermal coal with the addition of sawdust and pine needles (Bio-water-coal suspension). Methods. Experimental studies to determine the time characteristics of water-coal suspension ignition were carried out using a high-speed video camera FASTCAM. Fuel combustion was carried out in a flow-through combustion chamber equipped with magnetrons for additional microwave heating of the fuel. Dynamic viscosity was determined using a Brookfield RVDV-II + Pro viscometer. Results. It has been established that the addition of microwave heating can significantly (up to 15%) reduce the ignition delay of water-coal suspension and Bio-water-coal suspension at relatively low oxidizer temperatures (673 K). Experimental studies shown that the type of biomass affects the time characteristics of fuel ignition at ambient temperatures up to 753 K; with a further increase in the temperature of the oxidizer, the type of additive does not have a significant effect. It is shown that when studying the rheological characteristics of the water-coal suspension, the dynamic viscosity of Bio-water-coal suspension does not go beyond the characteristic value of 1200 Pa s at a shear rate of 100 rpm when no more than 2% of pine sawdust and no more than 6% of pine needles are introduced into the water-coal suspension.

This study used the proportional nodes method, a novel curve fitting approach to correlate data for dynamic viscosity of ammonia-water solution. The approach integrates polynomial equations, generated at various temperatures, with those calculated at selected mole fraction nodes. These nodes are scaling factors that account for variations in dynamic viscosity at different temperatures at selected mole fractions. The accuracy of the polynomial equations ensures a high degree of fitting accuracy. The proportional nodes, computed systematically, were integrated into a robust and highly accurate polynomial model to generate correlations that fit the data for the surface. This model exhibited minimal average percentage differences between predicted and actual viscosity values (±0.2614293 for temperature range, 273.15K to 303.15K and ±1.11 for temperature range, 303.15K to 423.15 K), indicating a high level of predictive accuracy. The proportional nodes method offers a significant contribution to both academic research and industry. It provides a more precise and adaptive model for predicting the dynamic viscosity of ammonia-water solution, which is critical for optimizing and designing various industrial applications, including refrigeration systems.

Nanofluids, as the fluids with modified thermal characteristics, are usable for improving the efficiency of renewable energy systems and enhancement of thermal management. Dynamic viscosity is one of the most significant features of fluids involved in their heat transfer and flow characteristics. This property of nanofluids is under effect of various elements and their modeling is somehow complex. Intelligent methods, regarding their outstanding performance in modeling complex problems, are attractive tool for this purpose. Due to the importance of dynamic viscosity, it is necessary to have accurate model for prediction of this property of nanofluids. Nanofluids with MgO nanoparticles have shown significant performance in thermal mediums and energy devices. In the present article, two intelligent approaches including Adaptive Neuro Fuzzy Inference (ANFIS) and Group Method of Data Handling (GMDH) are made use for modeling dynamic viscosity of nanofluids with MgO nanoparticles. Comparing the determined values by the intelligent methods and the actual quantities revealed significant function of the applied approaches. Among these two methods, using GMDH is preferred regarding its more exactness based on the statistical criteria. R2 of the mentioned methods based on GMDH and ANFIS were 0.9996 and 0.9616, respectively. Average Absolute Relative Deviation (AARD) is another criterion used for comparison of the proposed models that was around 5.13% and 19.41% for the mentioned models, respectively. According to these values, it is concluded that employment of GMDH is preferred in term of exactness.

Nanofluids are employed in variety of thermal energy systems owing to their modified properties and ability of enhancement in heat transfer. Among the properties of nanofluids, thermal conductivity and dynamic viscosity have significant role in the heat transfer characteristics and fluid flow specifications. Among the intelligent techniques, Support Vector Machines (SVMs) are attractive choices regarding their significant exactness in prediction and modeling. In this article, research works on the forecasting and modeling of the mentioned properties of nanofluids with SVMs are reviewed and their outcomes are presented. In accordance with the results of the reviewed works it can be stated that the developed approaches based on the SVM technique have shown significant performance in accurate modeling of both thermal conductivity and dynamic viscosity and can have superior performance in comparison with other intelligent methods in some cases. Furthermore, it can be pointed out that the performance of these systems is dependent on some elements like the employed optimization algorithms. Some recommendations are represented for future studies to reach models with more favorable performance.

As an environmentally friendly material, biochar is increasingly being utilized in the field of heat transfer and thermal conduction. In this study, nano-biochar was prepared from high-pressure homogenization (HPH) using sesame stalks as the raw material. It was incorporated into ethylene glycol (EG) and its dispersion stability, viscosity, and thermal conductivity were investigated. The nano-biochar was stably dispersed in EG for 28 days. When the concentration of the nano-biochar added to EG was less than 1%, the impact on viscosity was negligible. The addition of 5 wt.% nano-biochar to EG improved the thermal conductivity by 6.72%, which could be attributed to the graphitized structure and Brownian motion of the nano-biochar. Overall, nano-biochar has the potential to be applied in automotive thermal management.

Semiconducting nanofluids (SNFs) consisting of poly (ethylene glycol) (PEG200) as a green biocompatible base fluid with homogeneous dispersion of eco-friendly zinc oxide (ZnO) nanomaterial, concentrations ranging from 0.01 to 0.20 wt%, are prepared by state-of-the-art ultrasonic cavitation homogenized process. These PEG200/ZnO SNFs are characterized by employing an ultraviolet-visible (UV-Vis) spectrophotometer, precision inductance-capacitance-resistance (LCR) meter, and rotational viscometer. A detailed analysis of 200–800 nm range UV–Vis absorbance spectra of these SNFs revealed longer stability of suspended ZnO nanoparticles in PEG200 fluid, and their nanomaterial concentrations dependent absorbance and extinction coefficient with tunable dual energy band gaps ranging from 3 to 5 eV. Optical performance recognized the potential applications of these SNFs in the advances of soft matter based optoelectronic and photosensitive devices and also as an excellent UV radiation shielding material. The study of 20 Hz – 1 MHz range dielectric and electrical spectra explained that the ZnO concentrations have a significant impact on the electrical conductivity of these SNFs, while the dielectric permittivity and electrode polarization relaxation process are marginally altered. High static dielectric permittivity (∼ 22) and low electrical conductivity of about μS/cm order, at 303.15 K, evidence the suitability of these SNFs in advances of energy storage devices. The rheological behaviour of PEG200/ZnO materials is carried out at different temperatures ranging from 303.15 to 323.15 K, which illustrates the Newtonian characteristics of these nanofluids with moderate dynamic viscosity and activation energy, and therefore, they could be utilized as effective heat transfer materials in photovoltaic/thermal devices and systems.

This article proposes using the Arrhenius model for estimating the viscosity of a mixture of two liquids in the quantitative assessment of the physicochemical properties of lubricating oils in the context of assessing the level of dilution of lubricating oil with diesel oil. Dynamic are made of mixtures of lubricating oil and diesel oil with known concentrations of 0, 1, 2, 5, 10, 20, 50, and 100% m/m of the diesel oil content in the mixture. Mixtures of the most popular oils (viscosity classes SAE 30 and SAE 40) with diesel oil that meet the requirements of the DMX of the marine distillate fuels category are prepared and tested. Viscosity measurements are performed at 40, 50, 60, 70, 80, 90, and 100 °C temperatures. The Arrhenius model is used to estimate the viscosity of the mixtures with an assumed diesel oil content and to estimate the diesel oil concentration in the mixtures with a known measured viscosity value. In both cases, the absolute estimation error is determined, and the accuracy of the estimation is assessed against the known concentration of diesel oil in the mixture with lubricating oil and the temperature at which the viscosity is measured. The estimated concentrations of diesel oil in mixtures with lubricating oil are useful to assess the condition of the lubricating oil (for concentrations of diesel oil lower than 5% m/m). The method is proposed to be used in practice to support standard laboratory oil analysis. [ABSTRACT FROM AUTHOR]

The main emphasis of the current work is to study a proficient nanofluid model. Thermal conductivity of nanofluid is estimated via KKL (Koo–Kleinstreuer–Li) model keeping the nanoparticles influence up to 0.6%. Further, inclined magnetic field, viscous forces and Cattaneo–Christov effects are included in the analysis. The obtained KKL-nanofluid model is studied via LSM over the domain. From the model outcomes, it is examined that dynamic viscosity, density and heat capacity of the functional liquid enhanced from 1.0025 to 1.01516, 1.00706 to 1.04237 and 1.00106 to 1.00638, by taking the Al2O3 amount from 0.15 to 0.6%, respectively. Keeping the inclined Lorentz forces strength from 1.0 to 4.0 leads to drops in the fluid gesture in the lower half of the domain. Implication of magnetic field from various angles ( γ = 35 ∘ , 45 ∘ , 55 ∘ , 65 ∘) highly resists the movement. Moreover, inclusion of α 1 = 0.1 , 0.2 , 0.3 , 0.4 , α 2 = 0.2 , 0.4 , 0.6 , 0.8 , E c 1 = 0.1 , 0.2 , 0.3 , 0.4 and nanoparticles amount ϕ = 0.02 , 0.04 , 0.06 , 0.08 positively enhanced the working fluid temperature and the fluid molecules gained much temperature when the plate accelerated outward from the lower once. For the particular setup, the radiative flux and Lorentz forces in the existence of CCM controlled the fluid temperature. Thus, the temperature performance of the fluid diminished when the magnetic field acted through increasing angle. [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cell (PEMFC) seems to be a popular option as a green energy carrier due to its high efficiency and pollutant-free operation. However, the slight temperature difference between the working temperature and surroundings requires innovation in cooling strategy. Active thermal management strategy is limited due to the larger space requirement. Alternatively, utilizing nanofluids as coolant as the passive cooling strategy tends to be a viable quick fix. In this research, thermophysical properties of Al2O3:SiO2 hybrid nanofluids in the base fluid of water: Ethylene Glycol (EG) were discussed comprehensively concerning alterations made in thermal conductivity, dynamic viscosity, and electrical conductivity properties. There were four mixture ratios of 0.5% volume concentration of hybrid nanofluids considered ranging from 10:90, 30:70, 50:50, and 70:30 Al2O3:SiO2. Upon completion of the study, there is an improvement of 9.8% shown in 10:90 Al2O3:SiO2 hybrid nanofluids for thermal conductivity measured at 60°C in comparison to the base fluid. Meanwhile, 10:90 Al2O3:SiO2 hybrid nanofluids are also favorable with the lowest values of viscosity as compared to other mixture ratios resulting in lower parasitic loss. Electrical conductivity on the other hand also showed an increment in 10:90 Al2O3:SiO2 hybrid nanofluids as compared to base fluid and other mixture ratios. [ABSTRACT FROM AUTHOR]

The hydromagnetic flow of magnetite–water nanofluid due to a rotating stretchable disk has been numerically assessed. The nanofluid flow has been modeled utilizing the adapted Buongiorno model that considers the volume fraction-dependent effective nanofluid properties and the major slip mechanisms. In addition, experimentally gleaned functions of effective dynamic viscosity and effective thermal conductivity are deployed. The modeled equations are transformed into a first-order ODEs scheme employing Von Kármán's similarity conversions and then resolved via the Runge–Kutta algorithm through the shooting technique. The impact of pertinent terms over the physical quantities, nanoliquid temperature and nanoliquid concentration is explained with the support of graphs. Results show that rising volume fraction of magnetite nanoparticles (NPs) and magnetic field term enhance the drag force. Mass transport rate is demoted with augmenting values of magnetic field parameter whereas is promoted with increase in Schmidt number. Further, it is detected that the changes in stretching strength parameter are directly proportional to Nusselt number and inversely proportional to the thermal field. The findings of this numerical analysis have applications in spin coating, rotating disk reactors, storage devices for computers, food processing, and rotating heat exchangers. [ABSTRACT FROM AUTHOR]

A comprehensive theoretical and experimental study describing the effect of B 2 O 3 (0–30 wt%) on softening, liquidus, and crystallization temperatures, flow behaviour, and dynamic viscosity of the glass-based oxide system SiO 2 (64.64–43.21 wt%)-MgO(10 wt%)-CaO(15.86–7.29 wt%)-Al 2 O 3 (9.50 wt%)-B 2 O 3 with a constant basicity of 0.4 was carried out. The experimental data was obtained up to 1550 °C using a high-temperature rheometer and were supported by the study of the internal structure by means of scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray powder diffraction analysis, and Fourier transform infrared spectroscopy. The increasing addition of boron oxide caused a decrease in the start and end softening and liquidus temperatures. At 1550 °C, the systems exhibited Newtonian behaviour, with a dynamic viscosity increasing exponentially with a decreasing temperature and decreasing with increasing B 2 O 3 content. The amorphous character of the samples and the formation of structural units [BO 2 O−] and [BO 3 ] and [BO 4 ], confirmed by complementary analyses, led to a decrease in the degree of polymerization of the silicate structure. The theoretical insight into the dependence of dynamic viscosity on the temperature and composition was realized based on molecular dynamics. Furthermore, the prediction of viscosity as a function of temperature (1230–1550 °C) and the change in chemical composition (0–30 wt% B 2 O 3) was performed using artificial neural networks. [ABSTRACT FROM AUTHOR]

The method of boundary variation was applied to the solution of the boundary value problem with respect to the Reynolds differential equation for the lubricating layer in the sliding bearings of ship power plants and auxiliary ship equipment, which made it possible to obtain analytical representations for the hydrodynamic pressure, shear stresses, as well as the integral characteristics of the lubricating layer. This made it possible to build new, easy-to-use mathematical models for the load factor (carrying force factor) of the sliding pairs of the ship propulsion complex, considering the non-Newtonian properties of lubricants, i.e. in the case of the dependence of dynamic viscosity on pressure and temperature. Mathematical models take into account geometric parameters of bearings, operational parameters: relative radial clearance and relative eccentricity, angular velocity; as well as viscosity characteristics of lubricants, in particular, dynamic viscosity and piezo coefficient of viscosity of lubricants. A criterion for the presence of an oil layer in the working zone of the sliding pair at given operational characteristics and parameters of the sliding bearing is proposed, which considers the viscous characteristics of lubricants. The research results are illustrated in the form of tables and graphs. [ABSTRACT FROM AUTHOR]

The filtration of liquid in carbon fibers during their impregnation is considered. A quantitative relationship has been proposed between the mechanical compressive properties of long flat carbon threads and their permeability coefficient in the direction perpendicular to the surface of the thread. A model based on a nonstationary solution of a one-dimensional filtration problem has been developed for calculating the process of impregnation of fibers with a thermoplastic binder. As a result of a comparative analysis of experimental and calculated data, the dynamic viscosity of the melt and an analogue of its surface tension forces were assessed. [ABSTRACT FROM AUTHOR]

This work is aimed at the analysis of the development of flotation technology by applying carrier minerals. Based on the concepts of continuum mechanics, a theoretical analysis of the influence of the carrier minerals (wall) on the motion of a single solid particle is provided, taking into account their hydrodynamic interaction (in the case of low Reynolds numbers). A correction was obtained in the form of a ratio of the particle size to its distance from the wall to take into account the influence of the wall on the hydrodynamic force acting on the particle. The influence of the wall is manifested through a rapid approximation of the liquid vortex flow in the gap between the solid wall and the particle to the steady-state mode, accompanied by the suppression of the transverse movement of particles. When the liquid slides along a wall-mounted gas–liquid layer with a reduced viscosity, the liquid flow increases in the interfacial gap, which can be analyzed by a dimensionless correction that includes values describing the properties of a continuous medium (dynamic viscosity) and a disperse phase (geometric particle size). The reason for the decrease in the induction time when gold grains adhere to each other is assumed to be due to the forces of hydrophobic attraction (when the grains have a mirror-smooth surface) and the sliding of the flow along the hydrophobic surface of the particles along the gas layer (when the grains have a rough surface). When polydisperse particles are aggregated, the threshold energy of the fast coagulation was established to be lower than that arising during the interaction of monodisperse particles, whose aggregation requires a large depth of the potential pit. Performing natural experiments on the ore using a rougher concentrate as a carrier material showed that the concentrate yield decreases by 20.52% rel. In the second case, the gold extraction was higher by 4.69% abs. While maintaining the achieved level of gold extraction, the double mixing of the rougher concentrate and the initial feed increased the gold content in the rougher concentrate from 4.97 to 6.29 g/t. [ABSTRACT FROM AUTHOR]

The thermal examination of a non-integer-ordered mobile fin with a magnetism in the presence of a trihybrid nanofluid (Fe3O4-Au-Zn-blood) is carried out. Three types of nanoparticles, each having a different shape, are considered. These shapes include spherical (Fe3O4), cylindrical (Au), and platelet (Zn) configurations. The combination approach is utilized to evaluate the physical and thermal characteristics of the trihybrid and hybrid nanofluids, excluding the thermal conductivity and dynamic viscosity. These two properties are inferred by means of the interpolation method based on the volume fraction of nanoparticles. The governing equation is transformed into a dimensionless form, and the Adomian decomposition Sumudu transform method (ADSTM) is adopted to solve the conundrum of a moving fin immersed in a trihybrid nanofluid. The obtained results agree well with those numerical simulation results, indicating that this research is reliable. The influence of diverse factors on the thermal overview for varying noninteger values of γ is analyzed and presented in graphical representations. Furthermore, the fluctuations in the heat transfer concerning the pertinent parameters are studied. The results show that the heat flux in the presence of the combination of spherical, cylindrical, and platelet nanoparticles is higher than that in the presence of the combination of only spherical and cylindrical nanoparticles. The temperature at the fin tip increases by 0.705 759% when the value of the Peclet number increases by 400%, while decreases by 11.825 13% when the value of the Hartman number increases by 400%. [ABSTRACT FROM AUTHOR]

Addressing the issue of leakage in practical scenarios involving hose pumps, this paper conducts an analysis on hose pumps with existing compression gaps. The model is simplified to represent the two-dimensional Newtonian fluid pulsating flow of a single-sided sine wave passing through the tube. The study derives the axial flow velocity distribution within the tube while establishing correlations between the leakage volume, tube clearance, pressure differential, deformed cross-sectional length of the tube, rotor speed (which exhibits a negative correlation), the deformation length of the tube in the x-direction, and the fluid's dynamic viscosity (demonstrating a positive correlation). Utilizing a bidirectional fluid-structure coupling method, this analysis investigates hose pumps with compression gaps. Specifically, it examines the flow field pressure, velocity, and vortex intensity of two Newtonian fluids with Reynolds numbers of 10–30 and 6000–15 000, respectively, within a 180° bend tube with a curvature-to-inner-diameter ratio of 4.6. This analysis is conducted under inlet velocities of 0.32 and 0.6 m/s, and outlet pressures of 0 and 0.1 MPa. The study identifies the positions of extreme leakage rates, elucidating the flow field characteristics and their impact on leakage. Furthermore, it investigates the causes of secondary flows within the tube, concluding that the fluid inside the tube exhibits symmetric helical motion. This research establishes the periodic variations in flow field vortex intensity and secondary flow intensity, along with the conclusion that leakage rates are positively correlated with axial vortex intensity and negatively correlated with secondary flow intensity. [ABSTRACT FROM AUTHOR]

The direct application of Jatropha biodiesel in engines is harmful because of the corrosivity of biodiesel, the emission of poisonous gases, and solid particulate matter. Therefore, it is of paramount important to enhance the biodiesel fuel properties via green routes to effectively utilize it for automotive applications. The synthesis and application of different nanoparticles (NPs) such as ZnO, Mg‐ZnO, TiO2, and SiO2, as fuel property enhancers for Jatropha biodiesel were investigated. The calorific value, oxidation stability, dynamic viscosity etc. were studied for the NP‐blended biodiesels and compared with the traditional biodiesel (B100). Mg‐ZnO was found to be a promising candidate as fuel property enhancer for biodiesels. [ABSTRACT FROM AUTHOR]

Polymer blending with co-continuous morphology has garnered the interest of many researchers, but corresponding rheological models are rarely presented. In this study, the dynamic rheological behavior of a blend of polypropylene (PP) and low-density polyethylene (LDPE) in the ratio of 50/50 wt% is investigated, and a rheological model suggested by Yu et al. is used to fit the dynamic modulus. The rheological measurement shows that at low frequency, pure PP has higher complex viscosity and dynamic modulus than LDPE. SEM images reveal that the morphology among the 40/60 and 60/40 blends is non-dispersive. The fitting results indicate that the data at low frequency are underestimated by Yu model with lower coefficient KC, while the data are well-fit by the model with enough KC. Furthermore, the coefficient KB has no obvious influence on the fitting since B type structure in the original Yu model has a very weak contribution to dynamic modulus when orientation and distortion of the cylinders standing for the co-continuous structure cannot be neglected. The key coefficients in Yu model are KC and the characteristic length lc, while the co-efficient KB can be neglected. Thus, a simplified form of the model is suggested to predict the rheological dynamic modulus data for the PP/LDPE blending melt. [ABSTRACT FROM AUTHOR]

The article substantiates the importance of technological control of the production of plastic lubricants which characterizes physical, chemical or operational properties. Effective dynamic viscosity has been considered the most appropriate characteristics for technological control of for production of plastic lubricants. Effective dynamic viscosity of two-component plastic lubricant produced from secondary raw materials, as well as lubricants obtained using classical petroleum raw materials and soap thickeners, significantly depends on the viscosity of the base oil. It was defined that type of polymer thickener has rather insignificant effect on the value of the effective dynamic viscosity comparing to viscosity of the base oil. High-density polyethylene (HDPE) has the biggest thickening effect on the base oil, and polypropylene (PP) has the least. A diagram of location of the viscosity measuring sensors in the middle of the apparatus for dispersing the polymer thickener in base oil as a dispersion area was proposed. It helps to optimize the process of dispersing the polymer thickener by controlling the duration technological process that results in reducing the consumption of energy resources. [ABSTRACT FROM AUTHOR]

In this manuscript new experimental data for liquid density and dynamic viscosity for the mixtures composed by 2-isopropoxyethanol and 1-alkanol (C6 to C10) have been reported at 0.1 MPa and using 293.15 K, 303.15 K, 313.15 K, and 323.15 K. Cubic plus association equation of state was successfully applied to model the density of binary mixtures. Additionally, Kendall–Munroe correlation and Nguyenhuynh et al. correlation were used in the computation of dynamic viscosity. Finally, we have studied whether the intermolecular forces of attraction are strong or weak between 2-isopropoxyethanol and 1-alkanol. [ABSTRACT FROM AUTHOR]

Examining the behaviors of power-law nanofluid flow and the rate of heat transfer over different surfaces has received great attention due to its numerous industrial applications, such as polymer solutions, molten plastics, pulps, and foods. Also, the investigators focused on the case of constant viscosity, while in several practical situations, the dynamic viscosity of the power-law suspension is variable. So this study aims to examine non-similar solutions for the coupled flow of power-law non-Newtonian nanofluids over a truncated cone. The dynamic viscosity is varied according to the Reynolds viscosity model, and an exponential decaying form is considered for the internal heat generation. The non-Darcy model, where the quadratic drag is significant, is applied to formulate this situation, and the medium's permeability is varied according to the modified Ostwald-de-Waele power law model. Both the Arrhenius activation energy and non-linear thermal radiation impacts are considered. The solution methodology is based on the effective finite differences method with the Blottner scheme. The significant outcomes revealed that the rise in the power-law index n accelerates the flow and boosts the heat transfer rate. The values of the local Nusselt number in the case of the Darcy flow are higher than those of the non-Darcy case. Additionally, considering the case of variable dynamic viscosity, it is recommended to enhance the heat transfer rate. Furthermore, the rate of the heat transfer is enhanced by 29.1% viscosity parameter δ is varied from 0 to 0.5. [ABSTRACT FROM AUTHOR]

In this study, physical properties of nanofluids such as viscosity and thermal conductivity are investigated. Although there are many experimental and theoretical correlations and models available to predict these parameters, predictions are highly conflicting because the involved mechanisms are not fully understood. For instance, the predicted values of dynamic viscosity of γ-Al2O3/water nanofluids (at a volume fraction of 0.001) by different models range between 0.0005623 and 0.0403 kg/m.s and thermal conductivity ranges within 0.866 and 1.551 W/m-K under the same conditions. In this work, 184 experimental data of thermophysical properties of various metal oxide nanoparticle including Al2O3, SiO2, TiO2, Fe2O3, MgO, and CuO at a temperature range of 30 to 65 °C, diameter range of 10 to 50 nm, and volume fraction between 0.004% to 2% were collected from various publications. In this work, artificial neural network (ANN) has been implemented. The parameters of thermal conductivity and dynamic viscosity have been correlated to nanofluid concentration, temperature, particle size and molecular weight. It has been found that the topography of (4, 4, 4) from the ANN provides about 2% and 1% cross-validating and testing error respectively. Additionally, a sensitivity analysis was performed and the effect of individual parameters was analyzed. [ABSTRACT FROM AUTHOR]

In developed countries, gastro-oesophageal reflux is one of the most frequently diagnosed diseases. Although acid reflux is more well known, alkaline reflux is equally troublesome. In either of the two cases, the oesophageal mucosa is destroyed. The aim of this study was to analyse the possibility of eliminating the problem by using hydrogels containing dextran and chitosan to prevent irritation of the oesophageal mucosa. The addition of chitosan to all tested gels increased their dynamic viscosity, enabling better adhesion and, consequently, better protection of the mucous membrane. The addition of dextran reducedthepH ofthetestedgels, whichallawedfortheneutralisationofalkalinereflux. Based on the texture tests, chitosan and dextran increased work of adhesion. [ABSTRACT FROM AUTHOR]

Young children have an incompletely developed digestive tract and they are susceptible to numerous disorders due to the return of acid and alkaline content to the oesophagus. The aim of the study was to analyse the ability of hydrogels containing chitosan and polyvinyl alcohol to prevent irritation of the oesophageal mucosa in children. The addition of chitosan to the tested gels increased their pH, which could be useful to neutralise gastric reflux, and dynamic viscosity. The texture tests revealed that chitosan and polyvinyl alcohol significantly increased the work of adhesion work. [ABSTRACT FROM AUTHOR]

The article presents the results of tribological and rheological research of lubricating composition modified of various content of titanium dioxide. The analysis of anti-wear properties during the test for the tested lubricating composition indicates a significant change in this parameters for lubricants modified of titanium dioxide. A change of the value of evaluated tribological parameters leads to change in the structure of the composition carried out tests and a change in the effectiveness of the tribological protection of the tribosystem. The content of the thickener, base of oil and additive in the lubricant structure affects the level of the anti-wear properties, as evidenced by the results obtained during the tribological tests presented in this article. Also, the tribological tests were carried out with the T-02 four-ball machine for the base grease, i.e. without a modifying additive, and compared with the results obtained for lubricating greases modified with various amounts of titanium dioxide. The results of welding load, limiting pressure of seizure, scuffing load, limiting load of scuffing and limiting load of wear were used to evaluate the tribological properties. Based on the results of tribological tests of vegetable lubricating compositions, it was found, that the addition of titanium dioxide changed the anti-wear and anti-seizure properties of the vegetable lubricating compositions under study. The introduction of various amount of titanium dioxide caused an increase of dynamic viscosity at lower shear rates and significant changes of viscosity in the low temperatures. The introduction of modifier led to the decrease of yield point value from content value of used additive of tested lubricating compositions. [ABSTRACT FROM AUTHOR]

The ternary nanofluids are considered due to their advantages in overcoming the stability drawback of mono and binary nanofluids. This study aims to heat transfer performance of Al2O3-TiO2-SiO2 ternary nanofluids in plain tube with wire coil under experimental. The ternary nanofluids were formulated using the composition ratio of 20:16:64 by volume in various volume concentrations ranging from 0.5 to 3.0%. Thermal conductivity and dynamic viscosity of ternary nanofluids were measured with KD2 Pro Thermal Properties Analyzer and Brookfield LVDV III Rheometer. Experimental forced convection heat transfer was carried out using a fabricated setup for Reynolds numbers from 2,300 to 12,000 at bulk temperature of 70 °C in plain tubes with wire coil inserts (0.83 ≤ P/D ≤ 2.50). Experimental results are highest thermal conductivity enhancement of 24.8% was obtained for ternary nanofluids at 3.0% volume concentration. The 3.0% volume concentration also shows the highest viscosity at all temperatures. The maximum heat transfer improvement for ternary nanofluids in a plain tube with wire coil (P/D-0.83), was attained by 3.0% volume concentration of up to 199.23%. The average TPF of the wire coil increases compared to the plain tube and improves further with volume concentrations in the range of 2.39 to 2.84. [ABSTRACT FROM AUTHOR]

The size of nanoparticles influences the viscosity and thermal conductivity of a nanofluid flow. In this exploration, the impacts of the dynamic viscosity and thermal conductivity of the Corcione model on the magneto-hydrodynamics (MHD) Cu-water nanofluid flow over an exponentially stretched surface are examined. It is pertinent to mention that the whole scenario is done at 300 K and the freezing temperatures of 273.15 K with a particle size of 25 nm. The Navier slip and convective boundary conditions are assumed at the surface. A homogeneous single-phase model is adopted to formulate the problem. Nonlinear, coupled momentum, and energy balance nondimensionalized ordinary differential equations (ODEs) are constructed with suitable transformations. To solve these ODEs numerically, a renowned bvp4c technique of MATLAB software is employed. The effects of the arising parameters are represented graphically and numerically and are depicted in tables and graphs. It is witnessed that the velocity of the copper-water nanofluid declined with larger estimations of the volume fraction of nanoparticles, although the temperature distribution showed the reverse tendency. Moreover, at the surface for higher values of the slip parameter, the velocity profile reduces and the temperature of the fluid augments for higher values of the Biot number. The validation of the model is also executed by comparing it with the published result in the limiting case. An outstanding correlation is attained. [ABSTRACT FROM AUTHOR]

Surfactant-free microemulsion (SFME), an emerging phenomenology that occurs in the monophasic zone of a broad category of ternary mixtures 'hydrophobe/hydrotrope/water', has attracted extensive interests due to their unique physicochemical properties. The potential of this kind of ternary fluid for solubilization and drug delivery make them promising candidates in many industrial scenarios. Here the thermodynamic behavior of these multiscale nanodomains formed in the ternary trans -anethol/ethanol/water system over a wide range of temperatures is explored. The macroscopic physical properties of the ternary solutions are characterized, with revealing the temperature dependence of refractive index and dynamic viscosity. With increasing temperature, the ternary system shows extended areas in the monophasic zone. We demonstrate that the phase behavior and the multiscale nanodomains formed in the monophasic zone can be precisely and reversibly tuned by altering the temperature. Increasing temperature can destroy the stability of the multiscale nanodomains in equilibrium, with an exponential decay in the scattering light intensity. Nevertheless, molecular-scale aggregates and mesoscopic droplets exhibit significantly different response behaviors to temperature stimuli. The temperature-sensitive nature of the ternary SFME system provides a crucial step forward exploring and industrializing its stability. [ABSTRACT FROM AUTHOR]

Percutaneous drainage is a first-line therapy for abscesses and other fluid collections. However, experimental data on the viscosity of body fluids are scarce. This study analyses the apparent viscosity of serous, purulent and biliary fluids to provide reference data for the evaluation of drainage catheters. Serous, purulent and biliary fluid samples were collected during routine drainage procedures. In a first setup, the apparent kinematic viscosity of 50 fluid samples was measured using an Ubbelohde viscometer. In a second setup, the apparent dynamic viscosity of 20 fluid samples obtained during CT-guided percutaneous drainage was measured using an in-house designed capillary extrusion experiment. The median apparent kinematic viscosity was 0.96 mm2/s (IQR 0.90–1.15 mm2/s) for serous samples, 0.98 mm2/s (IQR 0.97–0.99 mm2/s) for purulent samples and 2.77 mm2/s (IQR 1.75–3.70 mm2/s) for biliary samples. The median apparent dynamic viscosity was 1.63 mPa*s (IQR 1.27–2.09 mPa*s) for serous samples, 2.45 mPa*s (IQR 1.69–3.22 mPa*s) for purulent samples and 3.50 mPa*s (IQR 2.81–3.90 mPa*s) for biliary samples (all differences p < 0.01). Relative to water, dynamic viscosities were increased by a factor of 1.36 for serous fluids, 2.26 for purulent fluids, and 4.03 for biliary fluids. Serous fluids have apparent viscosities similar to water, but biliary and purulent fluids are more viscous. These data can be used as a reference when selecting the drainage catheter size, with 8F catheters being appropriate for most percutaneous drainage cases. [ABSTRACT FROM AUTHOR]

It was proved that polymer–bitumen binders undergo a structural transformation after the addition of synthetic waxes. UV spectroscopy study showed that wax macromolecules and compounds of the dispersed oil system enter into chemical interactions, which was detected by the disappearance of the absorption band at 260 nm in the UV spectrum of the wax–bitumen blend. This suggested the formation of crosslinked reinforcing spatial structures, which explain the observed improvement in the performance properties of the polymer–bitumen binder after the addition of synthetic waxes: an increase in the softening temperature and brittleness temperature, a decrease in penetration, and an increase in their dynamic viscosity. It was determined that the transformation of the physicochemical characteristics of the polymer–bitumen binder after the addition of wax depends on its chemical nature. Waxes with an aliphatic branched polyethylene structure (Plastobit 430F, Plastowax 200TD, Plastowax 725T, Honeywell Titan 7686) more strongly change the physicochemical characteristics of the polymer–bitumen binder in comparison with waxes of the ProPolymer MA123 and ProPolymer MA-SK-02 brands, which are maleic anhydride–grafted linear polyethylene. [ABSTRACT FROM AUTHOR]

The plasticization of jelly obtained by structuring a sodium carboxymethyl cellulose solution with a complex salt of aluminum and citric acid was studied. Jelly base containing 1% sodium carboxymethyl cellulose and 15% glycerol had a dynamic viscosity of 4.7 Pa∙s, retained its shape, and was well lubricated. Stability studies of the gel base after storage for 24 months at 25 ± 10°C showed that the appearance, color, and smell did not change. The base remained uniform and stable. The pH value did not exceed the established limits. The thermal stability of gel samples was visually assessed in a thermostat at 40 – 42°C for 24 h. Phase separation was not observed in any of the gel samples. Gel samples met the requirements of bacteriological analysis. The inclusion of antibacterial (metronidazole, 0.25%) and antiseptic drugs (chlorhexidine, 0.025%) in the developed base statistically significantly increased the wound healing activity to 92 ± 4.5% (p < 0.05) as compared to the drug Levomekol (78 ± 3.8%, p < 0.05) in the ultraviolet erythema model. [ABSTRACT FROM AUTHOR]

Refrigerant R12, or Freon 12, has been a predominant choice in various refrigeration and air conditioning applications due to its versatility across a broad spectrum of operating conditions. However, R12, a chlorofluorocarbon (CFC) with the chemical formula CCl2F2, poses a significant threat to the ozone layer, contributing to the greenhouse effect. Consequently, the phasing out of R12 is imperative. This study explores viable alternatives to R12, focusing on the impact of external temperature and other parameters on capillary tube length. A detailed comparison between refrigerant R-134a and R-12 is conducted using Engineering Equation Solver (EES) software at Q=366.5 W, d= 1.2 mm, Tconf =45°C and tsurr=35°C. The software utilizes refrigerant thermodynamic and transport properties, including dynamic viscosity, density, thermal conductivity, and specific enthalpy, in the analysis. The research is aimed at understanding the flow dynamics in a capillary tube based on a model that aligns with the requirements of contemporary refrigerator design. Parameters such as operating conditions and tube diameter are scrutinized, with an emphasis on the direct relationship between them. The study also investigates the performance variability of the two refrigerants under identical conditions. A key finding is the superior quality of R-134a over R-12 in the two-phase region, coupled with the observation that the capillary tube length for R-134a is approximately 20% shorter than that for R-12. These results underscore the intricate relationship between refrigerant type, capillary tube dimensions, and overall system efficiency, thereby informing the design and optimization of next-generation refrigeration systems. [ABSTRACT FROM AUTHOR]