Presence Of Heat Research Articles

ANALISIS KANDUNGAN FLAVONOID PADA TEH BENALU (Dendropohtoe pentandra (L.) Miq.)

Background: Benalu is one of the plant species that lives attached to other plants. The parasite is hemiparasit or half parasitic because it has a green leaf substance (chlorophyll) used for the assimilation process and only sucks water and organic matter from its host plant. Flavonoids are phenol compounds commonly found in vascular plants including parasites. Flavonoids are useful for protecting cell structures, increasing the effectiveness of vitamin C, anti-inflammation, preventing bone loss and as an antibiotic.
 Method: Total flavonoid content in clove parasite tea using UV-Vis Spectrophotometer method.
 Results: Total flavonoid in tea clove parasite was 0.2819%. Flavonoids found in tea parasite cloves are low with the presence of heating and temperature factors.
 Conclusion: Based on the quantitative test, leaf parasite is the highest flavonoid level of 13.702% and after being made tea, flavonoid levels changed to 0.281%.

Modification of the Streptococcus mutans transcriptome by LrgAB and environmental stressors.

The Streptococcus mutans Cid/Lrg system is central to the physiology of this cariogenic organism, affecting oxidative stress resistance, biofilm formation and competence. Previous transcriptome analyses of lytS (responsible for the regulation of lrgAB expression) and cidB mutants have revealed pleiotropic effects on carbohydrate metabolism and stress resistance genes. In this study, it was found that an lrgAB mutant, previously shown to have diminished aerobic and oxidative stress growth, was also much more growth impaired in the presence of heat and vancomycin stresses, relative to wild-type, lrgA and lrgB mutants. To obtain a more holistic picture of LrgAB and its involvement in stress resistance, RNA sequencing and bioinformatics analyses were used to assess the transcriptional response of wild-type and isogenic lrgAB mutants under anaerobic (control) and stress-inducing culture conditions (aerobic, heat and vancomycin). Hierarchical clustering and principal components analyses of all differentially expressed genes revealed that the most distinct gene expression profiles between S. mutans UA159 and lrgAB mutant occurred during aerobic and high-temperature growth. Similar to previous studies of a cidB mutant, lrgAB stress transcriptomes were characterized by a variety of gene expression changes related to genomic islands, CRISPR-C as systems, ABC transporters, competence, bacteriocins, glucosyltransferases, protein translation, tricarboxylic acid cycle, carbohydrate metabolism/storage and transport. Notably, expression of lrgAB was upregulated in the wild-type strain under all three stress conditions. Collectively, these results demonstrate that mutation of lrgAB alters the transcriptional response to stress, and further support the idea that the Cid/Lrg system acts to promote cell homeostasis in the face of environmental stress.

Numerical study of heat source/sink effects on dissipative magnetic nanofluid flow from a non-linear inclined stretching/shrinking sheet

This paper numerically investigates radiative magnetohydrodynamic mixed convection boundary layer flow of nanofluids over a nonlinear inclined stretching/shrinking sheet in the presence of heat source/sink and viscous dissipation. The Rosseland approximation is adopted for thermal radiation effects and the Maxwell-Garnetts and Brinkman models are used for the effective thermal conductivity and dynamic viscosity of the nanofluids respectively. The governing coupled nonlinear momentum and thermal boundary layer equations are rendered into a system of ordinary differential equations via local similarity transformations with appropriate boundary conditions. The non-dimensional, nonlinear, well-posed boundary value problem is then solved with the Keller box implicit finite difference scheme. The emerging thermo-physical dimensionless parameters governing the flow are the magnetic field parameter, volume fraction parameter, power-law stretching parameter, Richardson number, suction/injection parameter, Eckert number and heat source/sink parameter. A detailed study of the influence of these parameters on velocity and temperature distributions is conducted. Additionally the evolution of skin friction coefficient and Nusselt number values with selected parameters is presented. Verification of numerical solutions is achieved via benchmarking with some limiting cases documented in previously reported results, and generally very good correlation is demonstrated. This investigation is relevant to fabrication of magnetic nanomaterials and high temperature treatment of magnetic nano-polymers.

Surface condition, microstructure and microhardness of boronized layers produced on Vanadis-6 steel after modification by diode laser

Abstract The paper presents the study results of surface condition, microstructure and microhardness of Vanadis-6 tool steel after diffusion boriding and laser modification by diode laser. As a result of diffusion boriding the layers consisted of two phases: FeB and Fe2B. A bright area under the continuous boronized layers was visible. This zone was probably rich in boron. As a result of laser surface modification of boronized layers, the microstructure composed of three zones: remelted zone, heat affected zone and the substrate was obtained. The microstructure of remelted zone consisted of boron-martensite eutectic. The depth of laser track (total thickness of remelted zone and heat affected zone) was dependent on laser parameters (laser beam power density and scanning laser beam velocity). The microhardness of laser remelting boronized layer in comparison with diffusion boronized layer was slightly lower. The presence of heat affected zone was advantageous, because it allowed to obtain a mild microhardness gradient between the layer and the substrate.

Influence of thermal radiation and chemical reaction in mixed convection stagnation point flow of Carreau fluid

Abstract This article is devoted to examine the mixed convection stagnation point flow of Carreau fluid with thermal radiation and chemical reaction. Heat transfer analysis is taken into account in the presence of heat generation/absorption. The developed nonlinear partial differential equations are reduced into the ordinary differential equations by suitable transformations. The governing equations are solved for the series solutions. The convergence of the series solutions for velocity, temperature and concentration fields is carefully analyzed. Numerical values of skin friction coefficient, Nusselt and Sherwood numbers are also computed and discussed in the presence of various sundry parameters. A comparative study is provided with the limiting available solution. It is concluded that velocity field enhances for material parameter. Reverse observation of heat generation holds for thermal field and local Nusselt number. Moreover influence of destructive chemical reaction parameter on the concentration and local Sherwood number are quite reverse.

Homogeneous-heterogeneous reactions in nonlinear radiative flow of Jeffrey fluid between two stretchable rotating disks

This article addresses MHD Jeffrey fluid flow between two stretchable rotating disks. Momentum equation with magnetic field is presented. Energy equation is constructed in presence of heat source/sink and nonlinear radiation. Thermal stratification and homogeneous-heterogeneous reactions are accounted. The related systems have been solved for convergent solutions. Velocity, temperature, concentration, skin friction coefficient and Nusselt number are analyzed. The velocities (radial, axial, tangential) are increasing functions of Deborah number. Decline in axial velocity is noticed at lower disk for larger ratio of relaxation to retardation times constant. Thermal field is enhanced for temperature ratio parameter. Concentration has opposite behavior for larger homogeneous parameter and Schmidt number. Surface drag force decays for larger ratio of relaxation to retardation times at both disks. Heat transfer rate enhances for temperature ratio parameter.

Overdamped stochastic thermodynamics with multiple reservoirs

After establishing stochastic thermodynamics for underdamped Langevin systems in contact with multiple reservoirs, we derive its overdamped limit using timescale separation techniques. The overdamped theory is different from the naive theory that one obtains when starting from overdamped Langevin or Fokker-Planck dynamics and only coincides with it in the presence of a single reservoir. The reason is that the coarse-grained fast momentum dynamics reaches a nonequilibrium state, which conducts heat in the presence of multiple reservoirs. The underdamped and overdamped theory are both shown to satisfy fundamental fluctuation theorems. Their predictions for the heat statistics are derived analytically for a Brownian particle on a ring in contact with two reservoirs and subjected to a nonconservative force and are shown to coincide in the long-time limit.

Physiological Flow of Jeffrey Six Constant Fluid Model due to Ciliary Motion

The main purpose of this article is to present a mathematical model of ciliary motion in an annulus. In this analysis, the peristaltic motion of non-Newtonian Jeffrey six constant fluid is observed in an annulus with ciliated tips in the presence of heat and mass transfer. The effects of viscous dissipation are also considered. The flow equations of non-Newtonian fluid for the two-dimensional tube in cylindrical coordinates are simplified using the low Reynolds number and long wave-length approximations. The main equations for Jeffrey six constant fluid are considered in cylindrical coordinates system. The resulting nonlinear problem is solved using the regular perturbation technique in terms of a variant of small dimensionless parameter α. The results of the solutions for velocity, temperature and concentration field are presented graphically. Bk is Brinkman number, ST is soret number, and SH is the Schmidth number. Outcome for the longitudinal velocity, pressure rise, pressure gradient and stream lines are represented through graphs. in the history, the viscous-dissipation effect is usually represented by the Brinkman number.

Radiative flow of a tangent hyperbolic fluid with convective conditions and chemical reaction

The objective of present paper is to examine the thermal radiation effects in the two-dimensional mixed convection flow of a tangent hyperbolic fluid near a stagnation point. The analysis is performed in the presence of heat generation/absorption and chemical reaction. Convective boundary conditions for heat and mass transfer are employed. The resulting partial differential equations are reduced into nonlinear ordinary differential equations using appropriate transformations. Series solutions of momentum, energy and concentration equations are computed. The characteristics of various physical parameters on the distributions of velocity, temperature and concentration are analyzed graphically. Numerical values of skin friction coefficient, local Nusselt and Sherwood numbers are computed and examined. It is observed that larger values of thermal and concentration Biot numbers enhance the temperature and concentration distributions.

Gumbrecht, Faulkner and the presence of heat

ABSTRACTIn setting out to examine the existence of presence, as opposed to meaning, in literature this essay draws on the work of Hans Ulrich Gumbrecht whose recent record of publications has formed a sustained response to this issue. Situating Gumbrecht’s work within two contexts – its debt to a phenomenological heritage and its congruence with more recent literary criticism – the essay argues for a renewed emphasis on presence via the concept of mood or stimmung. It then seeks to extend Gumbrecht’s work by offering an interpretation of William Faulkner’s 1932 novel Light in August which concentrates upon the palpable presence (stimmung) of heat which it contains. The existence of this heat, it will be argued, depends upon elements of the text that initially appear meaningful – or, to utilise Gumbrecht’s terminology, moments that are there primarily for their ‘meaning effect’ – but which analysis shows to be productive of presence. The essay concludes with a claim that what literary studies now requires is a re-ordering of the terms of emphasis in which discussions of meaning and presence are couched.

Investigation of Hall current and slip conditions on peristaltic transport of Cu-water nanofluid in a rotating medium

Main objective of present study is to analyze the effect of rotation on peristaltic transport of copper-water nanofluid. Two phase nanofluid is employed. The fluid fills the porous space. The channel walls are taken flexible. Hall current and viscous dissipation effects are also given consideration in the modeling. Analysis also studies the slip conditions in presence of heat generation/absorption. Resulting coupled system of equations is simplified by employing lubrication approach. Exact solutions are presented for the stream function whereas energy equation is solved numerically. Impact of sundry parameters on flow quantities are discussed and displayed via graphs. It is concluded that both axial (u) and secondary (v) velocities are reduced for increasing nanoparticle volume fraction (ϕ). Hartman number (M) and Hall parameter (m) have opposite effects on the velocity. Temperature (θ) enhances for increasing Hartman number (M).

An analytical solution for magnetohydrodynamic Oldroyd-B nanofluid flow induced by a stretching sheet with heat generation/absorption

This article provides an analytical investigation of magnetohydrodynamic (MHD) three-dimensional flow of an Oldroyd-B nanofluid in the presence of heat generation/absorption and convective surface boundary condition. Flow is induced by stretching surface considering the effects of Brownian motion and thermophoresis. The process of heat transfer is examined through the convective boundary condition. Oldroyd-B fluid is taken electrically conducting in the presence of a uniform applied magnetic field. A condition associated with nanoparticles mass flux at the surface is utilized. Problem formulation is made for boundary layer and low magnetic Reynolds number approximations. Suitable transformations are employed to construct the nonlinear ordinary differential equations. The strongly nonlinear differential equations are solved analytically through the optimal homotopy analysis method (OHAM). Effects of various interesting parameters on the temperature and nanoparticles concentration are studied and discussed. The local Nusselt number is also computed and analyzed. Our computations reveal that the temperature distribution has a direct relationship with Biot number and magnetic parameter.

MHD Stagnation Point Flow of a Casson Nanofluid Towards a Radially Stretching Disk with Convective Boundary Condition in the Presence of Heat Source/Sink

MHD Stagnation Point Flow of a Casson Nanofluid Towards a Radially Stretching Disk with Convective Boundary Condition in the Presence of Heat Source/Sink

Influence of nonlinear thermal radiation and variable viscosity on hydromagnetic heat and mass transfer in a thin liquid film over an unsteady stretching surface

This paper describes the influence of nonlinear thermal radiation on magnetohydrodynamic heat and mass transfer in a thin liquid film over a permeable unsteady stretching surface with temperature-dependent viscosity with convective boundary condition in the presence of heat source/sink and chemical reaction. The momentum, energy and mass-diffusion equations are highly non-linear. Thus the problem is solved numerically using Runge–Kutta–Fehlberg method with shooting technique. The shooting technique is essential to convert the boundary value problem to an initial value type. The results reveal that increase in the unsteadiness parameter leads to increase in the velocity distribution, temperature gradient and concentration gradient due to reduction in the thin film thickness. Further, increase in the value of magnetic parameter results in a decrease in the velocity profile and increase in the temperature and concentration gradient. Also, increase in the thermal radiation parameter decreases the temperature gradient. But there is decrease in the value of the concentration gradient by increasing the value of the Schmidt number.

Arginine as a protein stabilizer and destabilizer in liquid formulations

Even though arginine monohydrochloride (ArgHCl) is a useful additive for protein stabilization, its mechanism is not yet fully elucidated. Moreover, there is a concern that ArgHCl may be a protein denaturant since it decreases transition melting temperature (Tm) of certain proteins. It contains a guanidinium group, a critical structure for denaturating activity of guanidine hydrochloride (GndHCl). Effects of ArgHCl, GndHCl, and creatinine on a model protein, etanercept, were examined by biophysical analyses including DLS, DSC, FT-IR, microviscometer, and SEC. Accelerated storage stability of the protein was examined in the absence and presence of H2O2 at different incubation temperatures with pH monitoring. ArgHCl reduced protein aggregation and retained monomer, but increased fragmentation at high temperature. Tm1 and Tm2 of the protein increased with ArgHCl, but slight decrease (>1°C) in Tm3 was observed. GndHCl and creatinine decreased all three Tms. In the presence of heat and H2O2, the effect of ArgHCl was significantly decreased compared to GndHCl and creatinine. In addition, it accelerated the loss of monomer and increased fragmentation with decreasing pH. ArgHCl differed from GndHCl in the mode of physical interaction with the protein, due to its unique balance of three steric functional groups (guanidinium, carboxylic acid, and carbon aliphatic straight chain). In contrast, ArgHCl acted as a protein denaturant at high temperature since NOx generated from the amine group at the 3-carbon aliphatic straight chain and it is supported by GndHCl which did not change the pH nor accelerated the monomer loss after oxidation by H2O2 at high temperature.

Effects of temperature-dependent thermophysical properties on nanoparticle migration at mixed convection of nanofluids in vertical microchannels

The current paper investigates the effects of temperature-dependent thermophysical properties on nanoparticle migration at the mixed convective heat transfer of nanofluids inside microchannels in the presence of heat generation/absorption. The chief motivations of this study are to examine different modes of nanoparticle migration induced by asymmetric heating and to evaluate how temperature dependency influences the thermophysical properties of nanofluids. To those ends, the modified, two-component heterogeneous Buongiorno's model is employed for nanoparticle-fluid suspension, which takes into account nanoparticle slip velocity relative to the base fluid originating from thermophoretic diffusion—that is, a force driven by the temperature gradient—and Brownian diffusion, or a force driven by the nanoparticle concentration gradient. Due to surface roughness within the solid–fluid interface in microchannels, a slip condition is employed at the wall surfaces to assess the non-equilibrium region near the interface. Once the fluid flow is fully developed, governing equations including continuity, momentum, energy, and nanoparticle volume fraction are simplified to ordinary differential equations and solved numerically. The results are obtained with and without consideration of the dependency of thermophysical properties upon temperature. Results indicate that neglecting the temperature dependency of thermophysical properties does not significantly influence the flow fields and heat transfer behavior of nanofluids, but changes the relative magnitudes. Moreover, unlike temperature-dependent buoyancy force, concentration-dependent one exerts considerable effects upon flow fields and nanoparticle migration. Furthermore, one-sided heating enhances the heat transfer rate anomalously, especially for larger nanoparticles.

Stagnation point flow of a MHD Powell-Eyring fluid over a nonlinearly stretching sheet in the presence of heat source/sink

This study investigates the stagnation point flow of a MHD Powell-Eyring fluid over a nonlinearly stretching sheet in the presence of heat source/sink. Similarity transformations are used to convert highly non-linear partial differential equations into ordinary differential equations. The transformed nonlinear boundary layer equations are then solved numerically using Keller Box method. The effects of various physical parameters on the dimensionless velocity and temperature profiles are depicted graphically. Present results are compared with previously published work and the results are found to be in very good agreement. Numerical results for local skin-friction and local Nusselt number are tabulated for different physical parameters.

Comparison Between Casson Fluid Flow in the Presence of Heat and Mass Transfer From a Vertical Cone and Flat Plate

The present study explores the influence of viscous dissipation, Joule heating, and double dispersion on unsteady, free convective magnetohydrodynamics (MHD) flow of an incompressible Casson fluid over a vertical cone and flat plate saturated with porous medium subject to variable viscosity and variable electrical conductivity. The governing coupled, nonlinear partial differential equations are solved by Crank–Nicolson method. The effects of various significant parameters on flow, heat, and mass transfer characteristics are displayed in the form of figures and tables. The results indicate that the presence of variable viscosity parameter meagerly accelerates the fluid flow. It is observed that heat transfer is enhanced for increasing the thermal dispersion parameter and Eckert number.

Mixed Convection of Alumina/Water Nanofluid in Microchannels using Modified Buongiorno’s Model in Presence of Heat Source/Sink

Mixed Convection of Alumina/Water Nanofluid in Microchannels using Modified Buongiorno’s Model in Presence of Heat Source/Sink

Dual stratified mixed convection flow of Eyring-Powell fluid over an inclined stretching cylinder with heat generation/absorption effect

Present work is made to study the effects of double stratified medium on the mixed convection boundary layer flow of Eyring-Powell fluid induced by an inclined stretching cylinder. Flow analysis is conceded in the presence of heat generation/absorption. Temperature and concentration are supposed to be higher than ambient fluid across the surface of cylinder. The arising flow conducting system of partial differential equations is primarily transformed into coupled non-linear ordinary differential equations with the aid of suitable transformations. Numerical solutions of resulting intricate non-linear boundary value problem are computed successfully by utilizing fifth order Runge-Kutta algorithm with shooting technique. The effect logs of physical flow controlling parameters on velocity, temperature and concentration profiles are examined graphically. Further, numerical findings are obtained for two distinct cases namely, zero (plate) and non-zero (cylinder) values of curvature parameter and the behaviour are presented through graphs for skin-friction coefficient, Nusselt number and Sherwood number. The current analysis is validated by developing comparison with previously published work, which sets a benchmark of quality of numerical approach.