2,5-Disubstituted 1,3,4-oxadiazole compounds are one of the most attractive classes for researchers due to their pharmacological activities. In the current research, a new series of ...2-5-alkyl/aralkyl-1,3,4-oxadiazol-2-ylthio-N-4-(4-morpholinyl)phenylacetamides (6a–m) were prepared by converting different aryl/aralkyl organic acids (1a–m) successively into corresponding esters (2a–m), hydrazides (3a–m) and 5-aryl/aralkyl-1,3,4-oxadiazol-2-thiols (4a–m). Finally, the target compounds 6a–m were synthesized by stirring 5-aryl/aralkyl-1,3,4-oxadiazol-2-thiols (4a–m) with 2-bromo-N-4-(4-morpholinyl)phenylacetamide (5) in the presence of N,N-dimethylformamide (DMF) and sodium hydride (NaH). The structures of the synthesized compounds were elucidated through IR, 1H-NMR, 13C-NMR and mass spectral data. The compounds were also screened for antimicrobial and hemolytic activity and most of them were found to be active against the selected microbial species at variable extent relative to reference standards. The compounds, 6d and 6f were active against the selected panel of microbes and the former was the most potent one. This series showed less toxicity and may be considered for further biological screening and application trial except 6h and 6l, possessing higher cytotoxicity.
Two-phase natural convection dusty nanofluid flow Siddiqa, Sadia; Begum, Naheed; Hossain, M.A. ...
International journal of heat and mass transfer,
March 2018, 2018-03-00, 20180301, Volume:
118
Journal Article
Peer reviewed
Open access
•In this paper behavior of nanofluid is discussed in detail for two-phase dusty model.•The solutions are obtained through finite difference scheme.•The effects of the parameters on skin friction ...coefficient, rate of heat and mass transfer are explored.•It is concluded that the NA and NB has pronounced effect in reduction of heat transfer rate.
An analysis is performed to study the two-phase natural convection flow of nanofluid along a vertical wavy surface. The model includes equations expressing conservation of total mass, momentum and thermal energy for two-phase nanofluid. Primitive variable formulations (PVF) are used to transform the dimensionless boundary layer equations into a convenient coordinate system and the resulting equations are integrated numerically via implicit finite difference iterative scheme. The effect of controlling parameters on the dimensionless quantities such as skin friction coefficient, rate of heat transfer and rate of mass transfer is explored. It is concluded from the present analysis, that the diffusivity ratio parameter, NA and particle-density increment number, NB have pronounced influence on the reduction of heat transfer rate.
Y-type hexaferrite with nominal composition Ba2Co2Fe12O22 was synthesized by sol-gel method. The synthesized hexaferrite filler was mixed in 5 wt%, 15 wt% and 25 wt% respectively with Polyaniline ...(PANI) by insitu polymerization method to get hexaferrite-PANI composites. The synthesized samples were characterized by DC resistivity, XRD, VSM and dielectric measurements. The X-ray diffraction of polyaniline exhibit amorphous nature, whereas Ba2Co2Fe12O22exhibit single phase Y-type structure. Room temperature resistivity of the composites increased with increasing hexaferrite filler from 2.29 × 101 to 2.59 × 104 Ω-cm. Dielectric constant and complex dielectric constant measured in the frequency range of 1 Hz to 1 MHz. Both the real and imaginary parts of dielectric constant decreased with the increase of hexaferrite contents. AC conductivity was decreased with increasing Co2Y hexaferrite contents in PANI matrix and increased with increasing frequency following Maxwell-Wagner model. The saturation magnetization was observed to increase significantly with increasing hexaferrite filler, as it depends on volume fraction of magnetic particles and demagnetizing field produced by non-magnetic particles. Coercivity on average decreased with increasing hexaferrite filler which was due to the decrease in the inter particle distance and hence magneto static interactions enhanced amongst the particles. These composite materials are considered useful for applications of these materials in EMI shielding in low frequency range with added advantage of flexibility.
Turbulent convective flow in a cubic cavity is a fundamental model observed in various processes that appeared in environmental and industrial applications. The turbulent fluctuations in the flow ...field, fluid-solid interaction/coupling, and the transient nature of the problem make it challenging to establish numerical modeling. The turbulent flow and convective heat transfer in a cubic cavity fixed with three fins are studied here. The numerical solutions are obtained through large-eddy simulation with Smagorinsky subgrid-scale model combined with conjugate heat transfer to incorporate temperature distribution in solid fins. The upper and lower walls of the enclosure are differently heated, while the lateral walls are adiabatic, and equally spaced conductive fins are located at the bottom surface. The solutions are initially compared with the numerical and experimental results for validation purposes. Successively, the model is applied to explore the impact of a material (copper) that makes up the horizontal wall on the flow field. We found that the heat transfer essentially alters the turbulent field, and the flow field becomes less homogeneous along the vertical direction. A number of streaky and coherent turbulent structures are found with varying magnitudes. The Q-criterion, second-invariant of the velocity-gradient tensor, predicted that strong vortices occur near the fins and in the surrounding regions of the cavity. Moreover, the energy (entropy) spectral, which plays a crucial role in engineering applications and turbulent theory, is also presented, showing the contribution of each frequency component to the velocity (temperature) variance at a given point. The velocity and temperature fields are found to be anti-symmetric, except close to the front and back walls. The major cause for this is the conducting bottom and fins, which produces thermal stratification in the cavity. The conducting bottom induces the locally unstable thermal stratification in the vicinity of the wall, which intensifies the turbulence as the flow advances toward the temperature-controlled boundaries. Further, the turbulent exchange in the central region is more responsible for the heat transfer than convection that occurs due to the differentially heated walls.
In this paper bioconvection flow with heat and mass transfer of a water-based nanofluid containing gyrotactic microorganisms over a vertical wavy surface is investigated. The coupled nonlinear set of ...equations comprised of velocity, temperature, nanoparticle concentration and density of microorganisms is solved numerically by using implicit finite difference method. Flow characteristics are obtained in terms of skin friction coefficient, Nusselt number, Sherwood number and density number of microorganisms coefficient and are presented graphically by varying several controlling parameters. Interesting observations are recorded for the parameters: a, Nr, Lb and Rb. It is observed that the amplitude of the wavy surface has pronounced influence on the rates of heat and mass transfer, skin friction coefficient and density number of the microorganisms coefficient and all these quantities get augmented as the amplitude increases.
•In this study numerical solutions of the bioconvection boundary layer problem has been obtained along the vertical wavy surface.•The surface is embedded in the medium filled with a water based nanofluid containing gyrotactic microorganisms.•The governing equations were transformed into non-conserved form through appropriate transformations and solved numerically.•The solutions are presented graphically particularly for soil bacterium bacillus subtilis.
•Detailed numerical solutions for bioconvection of two-phase dusty nanofluid are given.•Dusty fluid contains gyrotactic microorganisms moving along the heated vertical plate.•Physical mechanisms such ...as thermophoresis and Brownian motion, are considered here.•The governing equations for two-phase model are non-dimensionalized and are solved numerically.•Solutions for important parameters are discussed graphically.
The aim of the present paper is to establish the detailed numerical results for bioconvection boundary-layer flow of a two-phase dusty nanofluid. The dusty fluid contains gyrotactic microorganisms along an isothermally heated vertical wall. The physical mechanisms responsible for the slip velocity between the dusty fluid and nanoparticles, such as thermophoresis and Brownian motion, are included in this study. The influence of the dusty nanofluid on heat transfer and flow characteristics are investigated in this paper. The governing equations for two-phase model are non-dimensionalized and then solved numerically via two-point finite difference method together with the tri-diagonal solver. Results are presented graphically for wall skin friction coefficient, rate of heat transfer, velocity and temperature profiles and streamlines and isotherms. To ensure the accuracy, the computational results are compared with available data and are found in good agreement. The key observation from the present analysis is that the mass concentration parameter, Dρ, extensively promotes the rate of heat transfer, Qw, whereas, the wall skin friction coefficient, τw, is reduced by loading the dust parameters in water based dusty nanofluid.
Carbon materials are considered as one the hardest materials in the nature and are potential candidates as reinforcement agents. Graphitic Carbon Nitride (g-C3N4) nano-rods have been synthesized by ...using melamine and are examined by XRD, SEM, EDS, TEM and FTIR for checking their structures, elemental analysis and phase purity. The synthesized g-C3N4 nano-rods are used in various compositions (0%, 0.5%, 1%, 2%, 3%, 4% and 5%) as reinforcement agents in Acrylonitrile Butadiene Styrene (ABS) which is extensively used in industrial applications. The results revealed that the tensile strength increases with the increase of g-C3N4 nano-rods in the ABS till some specific ratio (4%) but decreases with further increment of g-C3N4 nano-rods due to the agglomeration effect. Significantly, this enhancement in the tensile strength is better than other reinforcement agents and are crucial for industrial applications.
•In this paper two-dimensional biofluid is simulated in the rectangular channel, which is fully filled with the homogeneous porous media.•The blood flow is governed by the principles of ...magnetohydrodynamics and ferrohydrodynamics.•The main purpose of this study is to understand the impact of porous medium on the region where biofluid is subject to the application of localized magnetic field.•It is observed that the blood velocity can be control by adjusting the isotropic permeability which is the desirable requirement of surgical treatments for hyperthermia and cancer.
In this paper two-dimensional biofluid is simulated in the rectangular vessel, which is fully filled with the homogeneous porous media. Unlike the typical Navier–Stokes equations, the blood flow is governed by the principles of magnetohydrodynamics and ferrohydrodynamics. The main purpose of this study is to understand the impact of porous medium on the region where biofluid is subject to the application of localized magnetic field. The numerical results are estimated by keeping in view the applications in the field of magneto-haemorheology. Therefore, values of all the physical parameters, used for the interpretation of results, are in accordance with the pathological state. The solutions are presented in the form of vorticity function, streamlines, temperature function contours and velocity components. It is observed that the blood velocity can be controled by adjusting the isotropic permeability which is the desirable requirement of surgical treatments for hyperthermia and cancer.
The oncoprotein HER-2 is over-expressed and/or has undergone gene amplification in between 20 to 30% of breast and ovarian cancers. HER-2 amplified breast cancer is associated with a poor prognosis ...and increased resistance to chemo- and hormonal therapy. Data supporting the transforming potential of HER-2 are irrefutable but the mechanism by which HER-2 contributes to this process is complex and a unified model of HER2-induced increased cell proliferation and survival has not emerged.To understand the initial event(s) that take place by HER-2 over expression, we studied the effect of short term induction of HER-2 expression in the MCF7 breast cancer cell line.
We examined the modulation of apoptotic pathways by tetracycline-regulated HER-2 expression for 48 hrs in the MCF7 breast cancer cell line. Specific inhibitors were used to determine signalling pathways that are required for HER-2 induced up-regulation of survivin.
Tetracycline regulated short term over expression of HER-2 in the MCF7 cell line increased the antiapoptotic proteins Bcl-2 and survivin levels. Significant increase of extracellular signal-related kinase (ERK) activation but not AKT1, AKT2 and STAT3 was observed in HER-2 over-expressing MCF7 cells. Specific inhibitors of ERK, and phosphoinositide-3 kinase (PI3K), inhibited the HER-2 induced up-regulation of survivin. We did not observe a change in survivin and NF-kappaB promoter activity in HER-2 expressing MCF7 cells.
Our results indicate that short term over expression of HER-2 up regulates antiapoptotic proteins Bcl-2 and survivin in MCF7 cells. We determined that survivin is up-regulated via ERK activation and PI3K signalling. Additionally we show that survivin up-regulation is not at transcriptional level. These data provide insight into the mechanism(s) by which induction of HER-2 over expression up-regulates survivin and Bcl-2 and identifies new targets for therapy of breast cancer.
Two-phase natural convection flow of a dusty fluid Siddiqa, Sadia; Hossain, M. Anwar; Saha, Suvash C
International journal of numerical methods for heat & fluid flow,
09/2015, Volume:
25, Issue:
7
Journal Article
Peer reviewed
Purpose
– The purpose of this paper is to conduct a detailed investigation of the two-dimensional natural convection flow of a dusty fluid. Therefore, the incompressible boundary layer flow of a ...two-phase particulate suspension is investigated numerically over a semi-infinite vertical flat plate. Comprehensive flow formations of the gas and particle phases are given in the boundary layer region. Primitive variable formulation is employed to convert the nondimensional governing equations into the non-conserved form. Three important two-phase mechanisms are discussed, namely, water-metal mixture, oil-metal mixture and air-metal mixture.
Design/methodology/approach
– The full coupled nonlinear system of equations is solved using implicit two point finite difference method along the whole length of the plate.
Findings
– The authors have presented numerical solution of the dusty boundary layer problem. Solutions obtained are depicted through the characteristic quantities, such as, wall shear stress coefficient, wall heat transfer coefficient, velocity distribution and temperature distribution for both phases. Results are interpreted for wide range of Prandtl number Pr (0.005-1,000.0). It is observed that thin boundary layer structures can be formed when mass concentration parameter or Prandtl number (e.g. oil-metal particle mixture) are high.
Originality/value
– The results of the study may be of some interest to the researchers of the field of chemical engineers.
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