Abstract The study investigates the heat transfer and friction factor properties of ethylene glycol and glycerol-based silicon dioxide nanofluids flowing in a circular tube under continuous heat flux ...circumstances. This study tackles the important requirement for effective thermal management in areas such as electronics cooling, the automobile industry, and renewable energy systems. Previous research has encountered difficulties in enhancing thermal performance while handling the increased friction factor associated with nanofluids. This study conducted experiments in the Reynolds number range of 1300 to 21,000 with particle volume concentrations of up to 1.0%. Nanofluids exhibited superior heat transfer coefficients and friction factor values than the base liquid values. The highest enhancement in heat transfer was 5.4% and 8.3% for glycerol and ethylene glycol -based silicon dioxide Nanofluid with a relative friction factor penalty of ∼30% and 75%, respectively. To model and predict the complicated, nonlinear experimental data, five machine learning approaches were used: linear regression, random forest, extreme gradient boosting, adaptive boosting, and decision tree. Among them, the decision tree-based model performed well with few errors, while the random forest and extreme gradient boosting models were also highly accurate. The findings indicate that these advanced machine learning models can accurately anticipate the thermal performance of nanofluids, providing a dependable tool for improving their use in a variety of thermal systems. This study's findings help to design more effective cooling solutions and improve the sustainability of energy systems.
Effects of a hydrotropic salt, sodium salicylate (NaSal), on the dynamic behavior of cationic dodecyltrimethylammonium bromide (DTAB) micelles as studied using dynamic light scattering (DLS) and ...quasielastic neutron scattering (QENS) techniques are reported here. DLS study showed that the addition of NaSal leads to a decrease in the apparent diffusion coefficient of the whole micelle indicating micellar growth. QENS data analysis suggested that observed dynamics involves two distinct motions, lateral motion of the surfactant over the curved micellar surface and localized segmental motion of the surfactant. It is found that the addition of NaSal slows down the lateral motion of DTAB while the localized segmental motion of the DTAB chain is not affected much. An atomistic molecular dynamics (MD) simulation was performed to gain further insight into the underlying phenomena. MD simulation results are found to be consistent with the experimental observations. MD simulation revealed that location of the salicylate ions on the micellar surface and their strong electrostatic association with their oppositely charged surfactant headgroup are the major factors in slowing down the lateral motion of the DTAB molecule. In the present work, a quantitative description of the effects of NaSal on the nanoscopic dynamics of DTAB micelles and its correlation with the microstructure of the micelle is provided.
The low thermal properties of liquids have led to investigations into additives of small size (less than 100nm solid particles) to enhance their heat transfer properties and hydrodynamic flow. To ...summarise the experimental and numerical studies, this paper reviews these computational simulations and finds that most of them are in agreement with the results of experimental work. Many of the studies report enhancements in the heat transfer coefficient with an increase in the concentration of solid particles. Certain studies with a smaller particle size indicated an increase in the heat transfer enhancement when compared to values obtained with a larger size. Additionally, the effect of the shape of the flow area on the heat transfer enhancement has been explored by a number of studies. All of the studies showed a nominal increase in pressure drop. The significant applications in the engineering field explain why so many investigators have studied heat transfer with augmentation by a nanofluid in the heat exchanger. This article presents a review of the heat transfer applications of nanofluids to develop directions for future work. The high volume fraction of various nanofluids will be useful in car radiators to enhance the heat transfer numerically and experimentally. Correlation equations can expose relationships between the Nusselt number, the Reynolds number, the concentration and the diameter of the nanoparticles. On the other hand, more work is needed to compare the shapes (e.g., circular, elliptical and flat tube) that might enhance the heat transfer with a minimal pressure drop.
The development and clinical application of inhibitors that target the epidermal growth factor receptor (EGFR) provide important insights for new lung cancer therapies, as well as for the broader ...field of targeted cancer therapies. We review the results of genetic, biochemical and clinical studies focused on somatic mutations of EGFR that are associated with the phenomenon of oncogene addiction, describing 'oncogenic shock' as a mechanistic explanation for the apoptosis that follows the acute treatment of susceptible cells with kinase inhibitors. Understanding the genetic heterogeneity of epithelial tumours and devising strategies to circumvent their rapid acquisition of resistance to targeted kinase inhibitors are essential to the successful use of targeted therapies in common epithelial cancers.
Solidification morphology and centreline macrosegregation in continuously cast, thick steel slab samples were investigated in order to evaluate the liquid steel solidification characteristics and ...determine the severity of macrosegregation in cast slabs. Experimental studies were undertaken to establish the true solidification behaviour of industrial slab caster without electromagnetic stirring. Several slab samples collected from the continuous casting shop were utilized to characterize the solidification macrostructure, morphology of cast structure, and macrosegregation patterns. Macrostructural examination revealed predominantly coarse, columnar structure associated with high level of segregation which is detrimental to internal soundness of cast slabs. Liquid steels cast at high superheat (≥32°C) were generally having finer cast structures as compared to those cast at lower superheats (≤21°C). Degree of centreline segregation of Carbon (C), Phosphorus (P) and Manganese (Mn) were significantly high. Several unwanted phases (cementite, sulphide and phosphide) were also observed in the central segregated region of slab samples. An attempt was made to correlate the experimental observations with the operating parameters of the caster, and appropriate measures for improving the product quality were suggested.
The dynamics of phospholipids in unilamellar vesicles (ULVs) is of interest in biology, medical, and food sciences, since these molecules are widely used as biocompatible agents and a mimic of cell ...membrane systems. We have investigated the nanoscopic dynamics of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) phospholipid in ULVs as a function of temperature using elastic and quasielastic neutron scattering (QENS). The dependence of the signal on the scattering momentum transfer, which is a critical advantage of neutron scattering techniques, allows the detailed analysis of the lipid motions that cannot be carried out by other means. In agreement with a differential scanning calorimetry measurement, a sharp rise in the elastic scattering intensity below ca. 296 K indicates a phase transition from the high-temperature fluid phase to the low-temperature solid gel phase. The microscopic lipid dynamics exhibits qualitative differences between the solid gel phase (in a measurement at 280 K) and the fluid phase (in a measurement at a physiological temperature of 310 K). The analysis of the data demonstrates the presence of two types of distinct motions: the entire lipid molecule motion within a monolayer, also known as lateral diffusion, and the relatively faster internal motion of the DMPC molecule. The lateral diffusion of the entire lipid molecule is Fickian in character, whereas the internal lipid motions are of localized character, which is consistent with the structure of the vesicles. The lateral motion slows down by an order of magnitude in the solid gel phase, whereas for the internal motion not only the time scale but also the character of the motion changes upon the phase transition. In the solid gel phase, the lipids are more ordered and undergo uniaxial rotational motion. However, in the fluid phase, the hydrogen atoms of the lipid tails undergo confined translation diffusion rather than uniaxial rotational diffusion. The translational, but spatially localized, diffusion of the hydrogen atoms of the lipid tails is a manifestation of the flexibility of the chains acquired in the fluid phase. Because of this flexibility, both the local diffusivity and the confinement volume for the hydrogen atoms increase in the linear fashion from near the lipid’s polar headgroup to the end of its hydrophobic tail. Our results present a quantitative and detailed picture of the effect of the gel–fluid phase transition on the nanoscopic lipid dynamics in ULVs. The data analysis approach developed here has a potential for probing the dynamic response of lipids to the presence of additional cell membrane components.
Over the last couple of decades, deep eutectic solvents (DESs) have emerged as novel alternatives to ionic liquids that are extensively used in the synthesis of innovative materials, metal ...processing, catalysis, etc. However, their usage is limited, primarily because of their large viscosity and poor conductivity. Therefore, an understanding of the molecular origin of these transport properties is essential to improve their industrial applicability. Here, we present the report of the nanoscopic diffusion mechanism of acetamide in a DES synthesized with lithium perchlorate as studied using neutron scattering and molecular dynamics (MD) simulation techniques. A diffusion model is constructed with the help of MD simulation data comprising two distinct processes, corresponding to long-range jump diffusion and localized diffusion within a restricted volume. This diffusion model is validated through the analysis of neutron scattering data in the acetamide based DES (ADES) and molten acetamide. Although ADES has a remarkably lower freezing point compared to pure acetamide, the molecular mobility is found to be enormously restricted in the former. Particularly, the long-range jump diffusion process of acetamide is slower by a factor of 3 in ADES in comparison with molten acetamide. Further, the geometry of localized diffusion is found to be unaltered, but the dynamics is observed to be slightly slower in ADES. The diffusion model is found to be consistent over a wide temperature range for the ADES. Both long-range and localized diffusion show Arrhenius dependence with temperature in ADES. MD simulation analysis reveals that the long-range diffusion in ADES is restricted mainly due to the formation of hydrogen bond mediated complexes between the ionic species of the salt and acetamide molecules. Hence, the origin of higher viscosity observed in ADES can be attributed to the complexation in the ADES. The complex formation also explains the inhibition of the crystallization process while cooling and thereby results in depression of the freezing point of ADES.
Catanionic vesicles are formed spontaneously by mixing cationic and anionic dispersions in aqueous solution in suitable conditions. Because of spontaneity in formation, long-term stability, and easy ...modulation of size and charge, they have numerous advantages over conventional lipid-based vesicles. The dynamics of such vesicles is of interest in the field of biomedicine, as they can be used to deliver drug molecules into the cell membrane. Dynamics of catanionic vesicles based on sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) have been studied using incoherent elastic and quasielastic neutron scattering (QENS) techniques. Neutron scattering experiments have been carried out on two backscattering spectrometers, IRIS and IN16B, which have different energy resolutions and energy transfer windows. An elastic fixed-window scan carried out using IN16B shows a phase transition at ∼307 K during the heating cycle, whereas on cooling the transition occurred at ∼294 K. DSC results are found to be in close agreement with the elastic scan data. This transition is ascribed to a structural rearrangement from a multilamellar to a unilamellar phase Andreozzi J. Phys. Chem. B 2010, 114, 8056−8060 . It is found that a model in which the surfactant molecules undergo both lateral and internal motions can describe the QENS data quite well. While the data from IRIS have contributions from both dynamical processes, the data from IN16B probe only lateral motions, as the internal motions are too fast for the energy window of the spectrometer. It is found that, through the transition, the fraction of surfactant molecules undergoing lateral motion increases of a factor of 2 from the multilamellar to the unilamellar phase, indicating an enhanced fluidity of the latter. The lateral motion is found to be Fickian in nature, while the internal motion has been described by a localized translational diffusion model. The results reported here could have direct interest for a number of applications, such as molecular transport, and the effect of specific drug molecules or hormones through the membrane.
We propose a sensor based on spectral as well as angular interrogation of lossy mode resonance between absorbing thin film lossy modes and the evanescent wave for measurement of variation in the ...refractive index of the bulk media. It is shown that a low index dielectric matching layer introduced between the prism and the lossy waveguiding layer can produce an efficient refractive index sensor. The obtained sensitivity (4000–5000nm/RIU) is comparable to some of the best surface plasmon resonance (SPR) sensors. Unlike the SPR sensor in which surface plasmons can be excited only by p-polarized (TM) light, the proposed sensor can operate at either of these polarizations. Detailed theoretical analysis of the proposed sensor based on Fresnel reflection coefficients and transfer matrix method is presented. Effect of losses (imaginary part of refractive index) on the sensor parameters is also presented in sufficient details. Various parameters such as resonance angle, film thickness and refractive index of various layers are optimized for maximum evanescent field enhancement and increased sensitivity.
Most cancer patients die as a result of metastasis, thus it is important to understand the molecular mechanisms of dissemination, including intra- and extravasation. Although the mechanisms of ...extravasation have been vastly studied in vitro and in vivo, the process of intravasation is still unclear. Furthermore, how cells in the tumor microenvironment facilitate tumor cell intravasation is still unknown. Using high-resolution imaging, we found that macrophages enhance tumor cell intravasation upon physical contact. Macrophage and tumor cell contact induce RhoA activity in tumor cells, triggering the formation of actin-rich degradative protrusions called invadopodia, enabling tumor cells to degrade and break through matrix barriers during tumor cell transendothelial migration. Interestingly, we show that macrophage-induced invadopodium formation and tumor cell intravasation also occur in patient-derived tumor cells and in vivo models, revealing a conserved mechanism of tumor cell intravasation. Our results illustrate a novel heterotypic cell contact-mediated signaling role for RhoA, as well as yield mechanistic insight into the ability of cells within the tumor microenvironment to facilitate steps of the metastatic cascade.
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