In vivo, neutrophil motion is known to be propelled by concentration gradient of cytokine. However, the mechanism of propulsion has not been elucidated yet in the previous research. Based on the assumption that neutrophil is propelled by the concentration Marangoni effect, concentration gradient of cytokine on the neutrophil membrane and the neutrophil motion is investigated experimentally. In our previous investigations, it was found that neutrophil generate pseudopods for infiltration of organs near the wall. In this study, to investigate the phenomenon that neutrophil pseudopods generation near the wall, a microscopy-based observation experiment is conducted. The distance between the neutrophils and the wall and geometrical characteristics of the neutrophils are measured. From the results, the following three findings were obtained. First, arithmetic mean roughness and root mean square roughness are higher at distances of 2 and 4 μm from the wall surface. Second, skewness and kurtosis are highest value at distances of 2 μm from the wall surface. Third, neutrophil generates pseudopods at 4 μm from the wall surface and completely change shape at 2 μm. These findings suggest that near-wall interactions promote pseudopod-induced roughening that is likely to influence transport on the neutrophil membrane and, consequently, propulsion in cytokine gradients.
In the immune system, neutrophil movement toward the site of inflammation by concentration gradient is essential. In our previous studies, concentration gradient of cytokine on the neutrophil membrane is experimentally quantified. The results showed that the concentration gradient on the neutrophil membrane repeats positive and negative values while neutrophil moving. However, the key gap remains unclear: how external, membrane-scale cytokine gradient dynamics are coupled to intracellular signalling that drives protrusion and propulsion, and what the observed phase relationship implies for chemotaxis. In this study, the dynamics of intracellular calcium (Ca²⁺) in neutrophils were measured, and these findings were compared with previously measured cytokine concentration gradients to verify their correlation. The results show three main findings: (1) Neither IL-8 stimulation nor neutrophil viability produced a statistically significant change in the global intracellular Ca2+-indicator intensity or its decay rate. (2) The dominant frequencies of the membrane cytokine gradient and the intracellular Ca2+ gradient were similar, suggesting that external gradient dynamics and intracellular signaling are linked. (3) A consistent phase difference was observed between cytokine and Ca2+gradients, indicating a delayed intracellular response to changes in membrane cytokine gradients. These findings support a mechanistic role of calcium signaling in neutrophil propulsion and provide quantitative constraints for chemotaxis models.
One of the most important methods used to reduce manufacturing and maintenance costs for single-rotor wind turbines is to replace them with a multi-rotor turbine system, which captures the same amount of energy expended by the single turbine. The multi-rotor turbine system consists of several small turbines that reduce system loads and improve reliability. However, the use of this type of system faces many challenges, which many researchers and designers are working to overcome to reach an ideal design at the lowest cost in manufacturing, operation and maintenance with the best performance. This study presents the main reasons for using and developing multi-rotor wind turbines in terms of efficiency and cost, and the methods used by researchers and manufacturers to enhance the efficiency of this type of wind turbines. This review article will present an in-depth investigation of the power generating capabilities, cost concerns, and design characteristics of multi rotor wind turbines. By integrating current research and data on this revolutionary technology, this article hopes to add to the continuing conversation around sustainable energy alternatives and guide future developments in the field. Furthermore, multi-rotor turbines have faster wake recovery times, resulting in lower turbulence intensity in the wake than typical single-rotor turbines. Control of multi-rotor turbines is critical for reducing structural stress while increasing power output, necessitating advanced control algorithms and simulations. Noise prediction and control in multi-rotor systems provide additional issues, with rotor proximity influencing performance and noise production, demanding high-fidelity approaches for reliable predictions. Overall, while multi-rotor wind turbines improve performance, they also introduce complexity in design, control, and noise management that need careful analysis and innovative solutions.
Because of their potential to increase accessible area and overall heat diffusion, fins are often used as a thermal control approach for heat exchange. Nevertheless, these surfaces have undergone several modifications to improve their performance, one of which is perforation. Perforation shows outstanding promise in augmenting exchanged heat by enhancing turbulent stream and, most importantly, reducing the mass of these fins. The core goal of this review is to provide an extensive summarisation of the perforation impact as passive approaches that aim to enhance the thermo-hydraulic features of various fin forms that are employed in different applications, like heat sinks in electronics cooling, and heat exchangers in air-conditioning. Perforation in various fin shapes has been covered, such as (round, plate, longitudinal, pin, etc,) along with different parameters to investigate hole diameter, hole shape, hole quantity, hole distance, etc. Selected research was conducted under different conditions (forced and free convection, laminar and turbulent flow, and steady and unsteady). According to previous studies, drilled fins have a higher rate of heat than regular ones. The review concluded that freshly designed drilled fins outperform solid fins in enhancing the rate of heat transfer in a variety of thermal systems.
Refrigeration systems are integral to industries like food preservation, industrial processes, and air conditioning. As the demand for energy-efficient and environmentally friendly solutions grows, refrigeration lubricants have become crucial for improving system performance. However, selecting the right lubricant remains challenging due to the varying operating conditions in modern systems. This paper reviews the key properties of refrigeration lubricants, such as thermal stability, viscosity, chemical compatibility, and wear protection, which significantly influence system efficiency. The purpose of this study is to evaluate the effectiveness of both traditional and synthetic lubricants, particularly focusing on their compatibility with low-global-warming-potential (GWP) refrigerants and the impact of nanoparticles on lubricant performance. A comparative analysis of mineral oils and synthetic lubricants like polyol ester (POE), polyalkylene glycol (PAG), and polyvinyl ether (PVE) was conducted. Methods include a review of existing literature and performance data on lubricant-refrigerant compatibility, thermal stability tests, and the inclusion of nanoparticles to enhance lubricant properties. Results indicate that synthetic lubricants, which now account for over 50% of usage in refrigeration system, exhibit up to 30% better thermal stability and 25% improved chemical resistance compared to mineral oils. Nanoparticles, such as SiO2 and TiO2, were found to improve thermal conductivity by 10-15%, significantly enhancing system efficiency. The study concludes that selecting appropriate synthetic lubricants and incorporating nanoparticles can substantially improve the performance and sustainability of modern refrigeration systems.
Flat plate solar collectors play a vital role in energy sources. In this study, alumina nanoparticles have been used to improve the thermal performance of the solar collector. The effect of nanoparticles' size has been studied. In this study, three different sizes of nanoparticles are considered. The average size of nanoparticles was 25 nm in 0.5 vol. % Al2O3-water (Nanofluid 1), while 0.5 vol.% Al2O3-water (Nanofluid 2) owns 10nm average size of Al2O3. The third nanofluid (Nanofluid 3, 0.5 vol.% Al2O3-water) includes nanoparticles with average size of 50nm—the concentrations of nanoparticles equal to 0.5 vol. %. The experimentation undergoes Iraqi conditions in three selected months (January-February-March) during the daylight (9 A.M.-4 P.M.). The optimum size of nanoparticles is the one that gives a higher collector efficiency. The efficiency of FPSC of Nanofluid 2 outperforms Nanofluid 1 and Nanofluid 3 by 4.02% and 9.04%, respectively. Additionally, the effect of different flow rates (0.003, 0.007, 0.022, and 0.076) kg/s were studied. Increasing the flow rate would increase the heat flow of the fluid. However, these increments are highly sensitive to the size of nanoparticles. The results clarify that increasing the size of nanoparticles negatively influences the performance of solar collectors. This is due to the effect of agglomerations and sedimentations of nanoparticles. The maximum increment in efficiency was 32.3% for the 10 nm particle size.
The Reynolds number (Re) is a fundamental dimensionless parameter in fluid dynamics that governs the transition between laminar, transitional, and turbulent flow regimes, significantly influencing flow stability, energy dissipation, and heat transfer efficiency. Spiral pipes, characterized by their helical geometries, are widely used in industrial applications due to their ability to enhance thermal and hydraulic performance through the induction of centrifugal forces that generate secondary flows. This review systematically synthesizes findings from both experimental and numerical studies to explore the impact of Reynolds number on flow behavior in spiral pipe profiles. A PRISMA-based methodology was employed to ensure a structured literature selection process, incorporating key parameters such as Reynolds number variations, pipe geometry, and fluid rheology. The analysis reveals that higher Reynolds numbers promote secondary flow stabilization, improve axial velocity distribution, and reduce thermal resistance, particularly in non-Newtonian fluid applications. Despite these advancements, significant gaps remain in understanding complex flow dynamics under turbulent conditions. This study establishes a foundation for optimizing spiral pipe designs for energy-efficient applications in sustainable energy systems, biomedical devices, and industrial processes. Future research is encouraged to explore novel materials, advanced computational modeling, and experimental validations to further enhance the efficiency and applicability of spiral pipe configurations.
The COMSOL software is used to conduct a computational study of the two-dimensional steady laminar flow and thermal properties in a heated horizontal channel-open cavity with an angled baffle. The inclined baffle (with 30o) is placed at a length of 0.7 m from the inlet to ensure the development of the velocity profile. The channel walls' heated areas are at a fixed temperature. All other channel walls are maintained in an adiabatic state (no exchange of heat and matter between the system and its environment). The two heated sources of 20 W are located in the bottom and inclined right wall of the cavity. The utilised range of the input air velocity is (0.01, 0.05, 0.10, and 0.15 m/s). The current research delves into the influence of a number of key factors on the thermal, flow, pressure, and temperature characteristics of the system. These factors include the velocity of the input air, the presence of two heated sources, and the inclusion of an inclined baffle. Specifically, the research analysis the effects of these factors on the average Nusselt numbers and air mass distribution within the system. The numerical results establish a strong correlation with those found in the open literature. According to the numerical results, the regional velocity circulation is at its maximum near the channel inlet before its sudden fail due to the channel wall's shear stress. The pressure fluctuates at the junction of the channel and cavity, progressively drops throughout the channel's path. In this regard, the highest value of pressure is occurred at the channel's intake. The average Nusselt number rises as the air entering the system moves at a faster rate. Due to the recirculation effect, the existence of an angled baffle causes a sharp reduction in local temperature. The flow and temperature within the hollow alter visibly as the inlet air velocity rises.
The paper systematically explores the synthesis of epoxidized natural rubber (acetate and hydroxyl group) grafted chitosan (ENR(AcOH)-g-CTS) at varied epoxidation levels and mole ratios. Initially, ENR(AcOH) underwent controlled epoxide ring cleavage through optimized reflux times tailored to specific epoxidation levels. The reflux optimization significantly influenced the efficiency of epoxide cleavage. Functional group substitutions (Ac and O-H) were confirmed via ATR-FTIR analysis, which also demonstrated enhanced thermal resistance in ENR(AcOH) (Tmax increased by ~10.08%, Tg increased by ~68%) following successful cleavage. Structural analysis via XRD revealed a more amorphous polymer structure, indicative of the formation of new chemical bonds and increased molecular ordering within amorphous regions of ENR. Secondly, ENR(AcOH) was grafted with CTS at varying epoxidation levels and mole ratios (1:1, 1:3, and 1:4). Among these, the 1:4 mole ratio yielded a flexible standing film with superior properties. ATR-FTIR analysis confirmed the presence of substituted ether linkages (1300–1000 cm⁻¹), with the linkages increasing proportionally with CTS content. The TG/DTG analysis of ENR(AcOH)-g-CTS exhibited two decomposition steps attributed to the presence of a polymer chain mixture. The incorporation of CTS showed good thermal resistance upon ENR(AcOH)-g-CTS. Overall, the synthesized ENR(AcOH)-g-CTS enhanced natural rubber applications, offering distinctive improvements in characteristics compared to ENR and CTS.
In this study, the energy supply from fossil and nuclear power plants, wind energy, and solar PV is changeable. Their production is unpredictable, weather-dependent, and not always available when needed. It is also beyond human control. Variation results in variable production costs for renewable energy (VRE) as well as "integration costs" at the system level. The purpose of this work is to enhance the economic assessment of VRE, with a particular focus on their integration costs and diversity. Its three primary goals are to further knowledge in the field of variability economics. Consequently, it makes an effort to close the gaps between the three study fields that assess VRE. The integrated assessment model (IAM), the research on marginal economic value, and the integration costs literature. A framework for the economy of diversity was provided. It is predicated on a redefining of integration costs that encompasses all variable costs and, in contrast to earlier definitions, is more obviously tied to economic theory.
Mixed convection defines by the combination of buoyancy-driven (natural) and externally induced (forced) convection, which significantly affecting any fluid behaviour. The importance of mixed convection is underscored by its varied applications such as in aerospace engineering, renewable energy systems, and automotive engines. Hence, the current work presents a numerical analysis of mixed convection hybrid nanofluid flow over a vertically shrinking cylinder with velocity slip at the boundary conditions. The flow of Al2O3-Cu/H2O hybrid nanofluid is chosen based on its distinct nanoparticle properties, aimed to improve fluid thermal and transport characteristics. Governing Navier-Stokes equations are transformed into ordinary differential equations using similarity transformations. These equations, along with boundary conditions, are numerically solved using the bvp4c scheme in MATLAB. The effects of slip parameter, mixed convection parameter, nanoparticle volume fraction, and Reynolds number on the momentum and energy equations are observed and discussed in detail. The identification of two solution branches (first and second) is notified because of the shrinking parameter. Furthermore, this study offers insights into the complex behaviour of hybrid nanofluid flows and examines the impact of various parameters on fluid flow and thermal performance.
Batteries store chemical energy into electrical energy, making them crucial to clean energy systems, especially in hybrid and electric vehicles. For this application, a cylindrical LiNiMnCoO2 lithium-ion battery is popular. Temperature, material composition, current draw, and charge cycles affect battery performance. The study proposes a simulation-based approach for predicting internal battery temperature by analyzing temperature fluctuations observed during the discharging levels. For case studies, the battery had a capacity of 3.5 Ah and was tested at discharge levels of 0.5 C, 1 C, and 1.5 C. The results demonstrated stable thermal properties within the battery system. Moreover, the graph from natural convection studies decisively illustrated that the surrounding environmental temperature significantly impacts thermal measurements. This emphasizes the importance of environmental factors in battery performance and thermal management. Mesh-independent test profiles agreed with observed temperature values at 1 C. Mesh characteristics were obtained for each mesh element, providing confidence that is comparable to experimental results. Under insulated conditions, error margins were 2.71% at 0.5°C discharge, 2.1% at 1°C, and 1.77% at 1.5°C. The core internal battery's predicted thermal characteristics indicated the highest temperature. The safe operating temperature range for the core internal temperature of the LiNiMnCoO2 battery is 30°C to 45°C.
Metal oxide nanoparticles (MONPs) have garnered significant attention for their potential to enhance the thermal properties of nanofluids. This review delves into various types of MONPs, including oxides of copper, aluminum, zinc, titanium, and silicon, which have been extensively studied for their superior thermal conductivity, stability, and unique properties. Several synthesis techniques, such as sol-gel, hydrothermal, chemical vapor deposition, and thermal decomposition, are employed to fabricate MONPs with precise control over size, shape, and crystallinity. These nanoparticles are subsequently dispersed in base fluids like water, ethylene glycol, or oil to form nanofluids, utilizing methods such as ultrasonication, mechanical stirring, or chemical reduction. MONP-based nanofluids exhibit enhanced thermal conductivity compared to their base fluids, attributed to factors like increased effective thermal conductivity, Brownian motion of nanoparticles, and interfacial thermal resistance. However, challenges such as nanoparticle agglomeration and sedimentation can hinder their stability and long-term performance. The viscosity of MONP-based nanofluids generally increases with nanoparticle concentration, potentially impacting their flow behavior and pumping requirements. Nevertheless, their superior thermal conductivity often outweighs the viscosity penalty in many applications. MONP-based nanofluids have found diverse applications in various industries. In the energy sector, they are employed in solar thermal systems and heat exchangers to improve energy efficiency. In electronics, they serve as advanced thermal management fluids for cooling electronic devices. Future research directions include developing novel synthesis techniques for producing well-dispersed and stable MONP-based nanofluids, exploring hybrid nanofluids with synergistic effects, and investigating the underlying mechanisms responsible for enhanced thermal properties. By addressing these challenges and continuing to advance the field, MONP-based nanofluids hold the promise of revolutionizing thermal management and energy efficiency in various applications.
This paper uses CFD method to predict the submarine resistance in three different operating regimes: surface, near free surface and submerged at different speeds. The computed results revealed that operating regimes significantly affect total resistance. Besides, the variation in resistance components under three different operating regimes is provided and analysed in this paper. Moreover, the paper also provides images of the flow around the submarine’s hull to further clarify to change the ship's resistance component in different regimes. The numerical obtained results show that, the simulation results in submerged regime show good agreement with experimental data. The submarine model used in this study is the DARPA SUBOFF submarine model.
Hot air drying constitutes a critical preservation technique for Tilapia fillets, primarily aimed at reducing moisture content to inhibit microbial proliferation and extend shelf life. However, optimizing this process presents significant challenges due to the inherent sensitivity of Tilapia fillets to thermal and aerodynamic conditions, which profoundly influence both drying kinetics and product integrity. This study investigates the synergistic effects of varying drying temperatures (50°C, 60°C, 70°C) and air velocities (1.0 m/s, 1.5 m/s, 2.0 m/s) on drying kinetics and energy efficiency. Key performance indicators, including moisture content (MC), moisture ratio (MR), drying rate (DR), and specific energy consumption (SEC), were systematically evaluated. The results demonstrate that elevating the drying temperature to 70°C and increasing air velocity to 2.0 m/s significantly enhanced process efficiency, reducing drying time by 33%. Under these optimized conditions, the moisture content decreased from an initial 330% to below 50% within 200 minutes, while concurrently lowering the specific energy consumption (SEC) by 60% to 0.4 MJ/kg.
As the population and urbanization continue to expand rapidly, the demand for fuel is on the rise. Simultaneously, the depletion of natural fossil fuel resources is becoming more apparent. To decrease reliance on fossil fuels, particularly in the transportation sector, there is a growing adoption of biodiesel as a renewable energy source for various diesel engine applications. Biodiesel has the potential to deliver engine performance comparable to that of mineral diesel. However, challenges have emerged, such as issues with deposits, heightened emissions, and a decline in overall engine performance when using biodiesel as fuel. In this study, a review of the biodiesel’s droplet evaporation behavior and spray characteristics was conducted. The hot surface wall method and suspended droplet method were used to investigate the droplets’ evaporation behavior while the engine test was used to evaluate the fuel characteristics. For the droplet’s evaporation behavior, the main parameters involved were the physicochemical properties, surface temperature, addition of additives, and ambient temperature and pressure. These factors will determine the outcomes such as the droplet’s lifetime, splash, rebound, inflation, puffing, and micro-explosion. On the other hand, spray characteristics are often evaluated by the effect of fuel properties, injector design, injection timing/strategy, and ambient temperature and pressure. Furthermore, preheating and adding additives to the biodiesel were also found to be beneficial in terms of improving spray cone angle and spray penetration length, and results in better atomization and combustion of the biodiesel’s droplets. Finally, it is preferable to employ more than one method to evaluate biodiesel performance as more findings will help researchers and engine manufacturers to propose optimal biodiesel blend proportion and engine operating conditions.
The modeling of atmospheric pollutant dispersion in complex environments, particularly around buildings in urban areas, presents a significant challenge for environmental studies and air quality. This study aims to advance the development and application of Eulerian models for pollutant dispersion, utilizing Code_Saturne, a computational fluid dynamics (CFD) code. The approach is based on modeling the Reynolds-averaged Navier-Stokes (RANS) equations, incorporating closure via the simple gradient diffusion hypothesis (SGDH) to simulate the pollutant dispersion in airflow disturbed by a building, under uniform wind conditions and homogeneous turbulence. A comparative analysis of different building heights is conducted to assess their impact on flow structures and pollutant concentration distribution. The results underscore the considerable influence of urban obstacles on dispersion, leading to the formation of accumulation and recirculation zones that significantly modify pollutant distribution patterns. The proposed methodology validates the effectiveness of RANS-SGDH Eulerian modeling for studying atmospheric dispersion in urban areas, offering valuable insights for urban planning and air pollution management. Future work will focus on applying this approach to a real-world case in a Moroccan urban environment, further enhancing its relevance for practical environmental studies.
This study demonstrates findings related to the level of thermal comfort and adaptive behaviours of occupants in green campus residential colleges in Malaysia. The concept of green buildings in residential colleges can guarantee a balance of thermal comfort for the occupants. This study has utilized both qualitative and quantitative methods through the processes of data observation and survey questionnaire. The thermal comfort results show that average values of air temperature (27 oC-32.7 oC), relative humidity (63.4%-79.7%), and air velocity (0.0 m/- 0.1 m/s) which are not comfortable according to the standards set by DOSM and DOSH. However, residents can still accept such conditions while staying in the respective residential college. This is due to the fact that residents who live in green buildings have a higher tolerance compared to residents in conventional buildings. Furthermore, the design factor of the residential college equipped with a good natural ventilation system, as well as the effectiveness and usability of controls (windows, curtains, doors, etc.), has resulted in residents having high tolerance and adaptability traits to adjust to uncomfortable air temperatures, relative humidity, and airflow.
Water is one of the most important life resources and potable water is a very precious resource. Clean water is one of the most important challenges in modern world and one of the key goals of sustainable development. Use of solar energy to generate clean water through solar stills is a cost effective and highly sustainable method. The only drawback of solar stills in generating clean distilled water is its low output. A number of methods have been tried to increase the distillate output of the solar still. Augmentation with Phase Change Materials (PCMs) is one of the popular methods for increasing the output of the solar still by storing the heat energy in the PCM when the solar insolation is abundant during the daytime. Once the solar insolation starts to reduce in the evening, the heat stored in the PCM helps in keeping the temperature of the solar still high and increases its evaporation capacity. The passive solar still does not require any external power for sustaining its operations and augmentation of such solar still with PCM provides an excellent way to increase the utilization of solar energy. This paper reviews the literature reported on outcome of augmentation of passive solar stills with PCM. The modelling and simulation efforts and experimental work are described with a point of view to identify the different methods of augmentation of passive solar stills with PCM and compare the effectiveness of these approaches in improving solar still performance.
Natural dyes application for textiles is gaining wider acceptance as an eco-friendly approach, it is therefore ecoprint being one of the commonly used methods. In this study, three different ecoprint techniques of pounding, boiling, and steaming were evaluated in terms of their ability to generate imprints on lantung bark using teak leaves as a natural dye. Various colour fastness aspects such as that to washing, to sunlight and to rubbing were applied to assess the quality of ecoprinting. Furthermore, Fourier Transform Infrared Spectroscopy (FTIR) was applied to analyse the dyes functional group. The results revealed that pounding method seemed to fare best as the achieved colour fastness was quite exceptional in terms of washing (score 4), as well as exposure to sunlight (score 5) and the FTIR spectrum also indicated of strong intensity in both carbonyl (C=O) and hydroxyl (O-H) group which indicated a stable distribution of dyes. The boiling method gave the most optimal result for exposure to sunlight with a score of 5, however the washing score was around 3-4, would suggest that high temperatures may led to dye degradation. Steaming method provided moderate results with all ranges of scores 3-5 for washing and exposure to sunlight. A score of 3 was given for rubbing fastness, which suggests that the fixation agent might have fixed the dye quite well but lesser than that of pounding method. In light of these outcomes, the pounding technique is suggested as the most suitable method for producing ecoprint which retains its colour well. This study underlined the significance of the appropriate ecoprint technique selection in order to ensure the best ever colour in terms of quality and stability as well as justified the promotion of lantung bark-based eco-friendly textile dyeing.
