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This study focuses on an approximate analytical solution of the problem of laminar heat transfer of a fluid in a conical gap (rotating disk and a fixed cone) with small conicity angles up to 4° for high Prandtl numbers. A recently developed improved asymptotic expansion method for energy equation was applied. The characteristic Reynolds number Re took values of 0.1, 0.5, and 1.0, the Prandtl number Pr varied over a wide range from 1 to 3 × 106, whereas the exponent n* in the power law for the disk temperature was equal to 0 (isothermal disk) or 2 (quadratic increase along the radius). The new solution was obtained using a new expansion parameter SvT = Re2Δ2Pr (a new dimensionless number first formulated here). This parameter involves the relative thickness of a thermal boundary layer Δ on the disk, which is less than the gap height. New approximate analytical solutions for the Nusselt numbers and the value of Δ on the disk are in good agreement with the self-similar solution. The exponent at the Pr and Re numbers are 1/3 and 2/3, respectively. These solutions are valid for SvT ≥ 7,...,7.65 (with the lowest values of Pr = 700). The boundaries of the solution for moderate Prandtl numbers can be extended to Sv ≤ 25, when the thermal boundary layer does not emerge on the disk (with the highest values of Pr = 2000). The new analytical solutions are advantageous in the analysis of experimental data on heat transfer for mineral oils, and in convective diffusion in electrochemistry. [ABSTRACT FROM AUTHOR]

The present study investigates the entropy generation of chemically reactive micropolar hybrid nanoparticle motion with mass transfer. Magnetic oxide (Fe3O4) and copper oxide (CuO) nanoparticles were mixed in water to form a hybrid nanofluid. The governing equations for velocity, concentration, and temperature are transformed into ordinary differential equations along with the boundary conditions. In the fluid region, the heat balance is kept conservative with a source/sink that relies on the temperature. In the case of radiation, there is a differential equation along with several characteristic coefficients that transform hypergeometric and Kummer's differential equations by a new variable. Furthermore, the results of the current problem can be discussed by implementing a graphical representation with different factors, namely the Brinkman number, porosity parameter, magnetic field, micropolar parameter, thermal radiation, Schmidt number, heat source/sink parameter, and mass transpiration. The results of this study are presented through graphical representations that depict various factors influencing the flow profiles and physical characteristics. The results reveal that an increase in the magnetic field leads to a reduction in velocity and entropy production. Furthermore, temperature and entropy generation rise with a stronger radiation parameter, whereas the Nusselt number experiences a decline. This study has several industrial applications in technology and manufacturing processes, including paper production, polymer extrusion, and the development of specialized materials. [ABSTRACT FROM AUTHOR]

Hybrid nanofluids have caught the attention of scholars and investigators in the present technological period due to their improved thermophysical features and the desire to boost heat transfer rates compared to those of conventional fluids. The present paper is mainly concerned with heat transmission in cone-disk geometry in the presence of a magnetic field, activation energy, and non-uniform heat absorption/generation. In this work, the cone-disk (CD) apparatus is considered to have a rotating cone (RC) and a stretching disk, along with iron oxide and cobalt ferrite-based hybrid nanofluid. Appropriate similarity transformations are employed to change the physically modeled equations into ordinary differential equations (ODEs). Heat transfer rates at both surfaces are estimated by implementing a modified energy equation with non-uniform heat absorption/generation. The outcomes illustrated that the inclusion of such physical streamwise heat conduction variables in the energy equation has a significant impact on the well-known conclusions of heat transfer rates. To understand flow profile behavior, we have resorted to the RKF-45 method and the shooting method, which are illustrated using graphs. The findings provide conclusive evidence that wall stretching alters the flow, heat, and mass profile characteristics within the conical gap. The wall deformation caused by disk stretching was found to have a potential impact of modifying the centripetal/centrifugal flow characteristics of the disk, increasing the flow velocity and swirling angles. A rise in activation energy leads to an improved concentration field. [ABSTRACT FROM AUTHOR]

The article presents the results of an analytical study of the flow dynamics in a microdiffuser. An expression for the velocity profile is obtained with account for slip effects. The effect of the Knudsen number on the velocity profiles is shown. The effect of the microdiffuser angle on the flow velocity profile and the friction coefficient is analyzed. The opening angle of the microdiffuser was determined, at which slip effects do not affect the velocity profile. [ABSTRACT FROM AUTHOR]

The main objective of this study is to explore the inventive conception of the magnetohydrodynamic flow of a hybrid nanofluid over-porous stretching/shrinking sheet with the effect of radiation and mass suction/injection. The hybrid nanofluid advances both the manufactured nanofluid of the current region and the base fluid. For the current investigation, hybrid nanofluids comprising two different kinds of nanoparticles, aluminium oxide and ferrofluid, contained in water as a base fluid, are considered. A collection of highly nonlinear partial differential equations is used to model the whole physical problem. These equations are then transformed into highly nonlinear ordinary differential equations using an appropriate similarity technique. The transformed differential equations are nonlinear, and thus it is difficult to analytically solve considering temperature increases. Then, the outcome is described in incomplete gamma function form. The considered physical parameters namely, magnetic field, Inverse Darcy number, velocity slip, suction/injection, temperature jump effects on velocity, temperature, skin friction and Nusselt number profiles are reviewed using plots. The results reveal that magnetic field, and Inverse Darcy number values increase as the momentum boundary layer decreases. Moreover, higher values of heat sources and thermal radiation enhance the thermal boundary layer. The present problem has various applications in manufacturing and technological devices such as cooling systems, condensers, microelectronics, digital cooling, car radiators, nuclear power stations, nano-drag shipments, automobile production, and tumour treatments. [ABSTRACT FROM AUTHOR]

The focus of this paper was Jouguet detonation in an ideal gas flow in a magnetic field. A modified Hugoniot detonation equation has been obtained, taking into account the influence of the magnetic field on the detonation process and the parameters of the detonation wave. It was shown that, under the influence of a magnetic field, combustion products move away from the detonation front at supersonic speed. As the magnetic field strength increases, the speed of the detonation products also increases. A dependence has been obtained that allows us to evaluate the influence of heat release on detonation parameters. [ABSTRACT FROM AUTHOR]

IntroductionHuman colorectal cancer (HCC) is one of the main causes of cancer-related mortality worldwide (Jemal et al. 2011). It is a very aggressive neoplasm with high metastatic potential (Vatandoust et [...], The aim of this work was to explore the key bioenergetic properties for mitochondrial respiration in the widely-used Caco-2 cell line and in human colorectal cancer (HCC) postoperational tissue samples. Oxygraphy and metabolic control analysis (MCA) were applied to estimate the function of oxidative phosphorylation in cultured Caco-2 cells and HCC tissue samples. The mitochondria of Caco-2 cells and HCC tissues displayed larger functional activity of respiratory complex (C)II compared with CI, whereas in normal colon tissue an inverse pattern in the ratio of CI to CII activity was observed. MCA showed that the respiration in Caco-2 and HCC tissue cells is regulated by different parts of electron transport chain. In HCC tissues, this control is performed essentially at the level of respiratory chain complexes I-IV, whereas in Caco-2 cells at the level of CIV (cytochrome c oxidase) and the ATP synthasome. The differences we found in the regulation of respiratory chain activity and glycose index could represent an adaptive response to distinct growth conditions; this highlights the importance of proper validation of results obtained from in-vitro models before their extrapolation to the more complex in-vivo systems.Key words: colorectal cancer, mitochondrial metabolism, OXPHOS, metabolic control analysis.L'objectif de ce travail etait d'explorer les principales proprietes bioenergetiques de la respiration mitochondriale dans les cellules de la lignee largement utilisee Caco-2 et dans des echantillons de tissus postoperatoires de cancer colorectal humain (CCH). L'oxygraphie et l'analyse du controle metabolique (MCA, << metabolic control analysis>>) ont ete utilisees pour estimer la fonction de la phosphorylation oxydative dans les cellules Caco-2 en culture et dans des echantillons de tissus de CCH. Le complexe respiratoire (C)II des mitochondries des cellules Caco-2 et des tissus de CCH etait fonctionnellement plus actif que le CI, alors que l'inverse est observe dans le colon normal en ce qui concerne le rapport des activites du CI et du CII. La MCA montrait que la respiration des Caco-2 et des tissus de CCH est regulee par differents segments de la chaine de transport electronique. Dans le tissu de CCH, ce controle est essentiellement assure par les complexes I-IV de la chaine respiratoire alors que dans les cellules Caco-2, il est assure par le CIV (cytochrome c oxydase) et le synthasome d'ATP. Les differences revelees dans la regulation de l'activite de la chaine respiratoire et l'indice de glucose pourraient representer une reponse adaptative a des conditions de croissances distinctes; cela souligne l'importance de bien valider les resultats obtenus a partir de modeles in vitro avant de les extrapoler a des systemes in vivo plus complexes. [Traduit par la Redaction]Mots-cles: cancer colorectal, metabolisme mitochondrial, OXPHOS, analyse du controle metabolique.