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J Hemalatha - One of the best experts on this subject based on the ideXlab platform.

  • synthesis and viscosity studies of novel ecofriendly zno coconut oil nanofluid
    Experimental Thermal and Fluid Science, 2013
    Co-Authors: Nabeel M Rashin, J Hemalatha
    Abstract:

    Novel nanofluid of zinc oxide in coconut oil has been synthesized in various concentrations through ultrasonically assisted two step method. Structural and morphological studies of nanoparticles are made with the help of X-ray diffraction and Transmission Electron Microscope and it is found that the particles posses hexagonal structure with an average size of 26 nm. Viscosity of the nanofluid has been measured at various temperatures and shear rates from which the shear thinning behavior is observed in all the samples. The shear thinning is observed to be higher at low shear rates and also at high concentrations. Higher degree of shear thinning at low concentration range is attributed to the shear thinning nature of Carrier Liquid, but at higher concentration range there is a substantial contribution from particle – fluid interaction. The experimental viscosities of nanofluids are compared with the theoretical values obtained through Einstein, Batchelor and Wang models. A small deviation is observed which may arise due to the difference in the morphology, chemical composition and interactions. New empirical relations are proposed for predicting the viscosity of coconut oil based ZnO nanofluid at various temperatures and concentrations.

  • viscosity studies on novel copper oxide coconut oil nanofluid
    Experimental Thermal and Fluid Science, 2013
    Co-Authors: Nabeel M Rashin, J Hemalatha
    Abstract:

    Abstract Novel coconut oil based copper oxide nanofluids of various concentrations have been prepared by ultrasonically assisted two step method. Viscosity studies have been made experimentally and theoretically at various temperatures and shear rates for different concentrations of nanofluid ranging from 0% to 2.5%. Shear thinning, a non-Newtonian behavior is observed in all the samples. The shear thinning is higher at lower shear rates and higher concentrations. The shear thinning at low concentration is attributed to the non-Newtonian behavior of Carrier Liquid, but at higher concentration there is a considerable contribution from particle too. The measured viscosities of nanofluids are compared with existing theoretical models and found to have very slight deviation due to size, morphology and interactions. New empirical correlations are proposed for predicting viscosity of CuO–coconut oil nanofluid at various temperatures and concentrations.

Martin Brandl - One of the best experts on this subject based on the ideXlab platform.

  • liposome fractionation and size analysis by asymmetrical flow field flow fractionation multi angle light scattering influence of ionic strength and osmotic pressure of the Carrier Liquid
    Chemistry and Physics of Lipids, 2010
    Co-Authors: Stefan Hupfeld, Helene H Moen, Dominik Ausbacher, Heinrich Haas, Martin Brandl
    Abstract:

    Abstract Asymmetrical flow field-flow fractionation (AsFlFFF)/multi-angle light scattering (MALS) was employed for studying filter-extruded liposomes in Carrier solutions with different ionic strength and osmolarity. By dilution of preformed liposome suspensions with different media, only the ionic strength in the external free aqueous phase was changed. Under such conditions the liposomes were found to elute at almost identical elution times, which is in contrast to earlier studies. This may be explained by two opposing effects: (a) modulation of inter-particulate and particle-wall-repulsion effects and (b) osmotic stress-induced changes in vesicle size. The latter effect was demonstrated when analysing liposomes upon dilution in media of constant ionic strength, but varying osmotic pressure (with or without 150 mmol L−1 sucrose supplement). The osmotic stress-induced change in liposome size was found to be size dependent. Larger liposomes appeared to both shrink and swell when exposed to hyper- or hypoosmotic media, respectively. Smaller liposomes appeared to shrink but not to swell. The potential causes of this effect are discussed.

Seungbok Choi - One of the best experts on this subject based on the ideXlab platform.

  • the influence of particle size on the rheological properties of plate like iron particle based magnetorheological fluids
    Smart Materials and Structures, 2015
    Co-Authors: Kruti Shah, Seungbok Choi
    Abstract:

    This work is devoted to the dependence of particle size on magnetorheological properties of magnetorheological fluid (MRF) consisting of plate-like iron particles suspended in a Carrier Liquid with two aspects. One aspect is to study the influence of the particle size on the rheological properties of the MRF, and the other is to investigate the influence of small-sized particles on the large-sized MRF. In order to achieve this goal, firstly, two different types of MR suspensions have been constituted by a plate-like iron particle; one is small with an average particle size of 2 μm in diameter, and the other is large with an average particle size of 19 μm in diameter. In this work, these are denoted as S-MRF and L-MRF, respectively. Secondly, in order to check the influence of the small particle size of the large-sized MR fluid, three different weight fractions of bidisperse MRF samples are prepared. The structural and morphology of plate-like iron particles are described in detail. The magnetic properties of these MR fluids are carried out at room temperature using the magnetometer, followed by the investigation on the field-dependent rheological properties of these MR fluids. It is observed that in both the S-MRF and L-MRF, the yield stress and viscosity is increased by the increasing particle size, which directly shows a correlation with the fluid magnetization. It is also identified from the test of the bidisperse MRF samples that the yield and viscosity depend on the weight fraction due to the magnetostatic interaction between the two different sizes of particles. Based on the rheological properties, some figures of merit are derived for the proposed MRF samples, which are important in the design of the application device. The sedimentation experiments for MRF samples are performed to check the stability of the MRF each day. With the basic rheological properties and sedimentation experiments, it is clearly demonstrated that the bidisperse MR suspension with a precise weight fraction has high yield stress and low sedimentation stability, which shows practical feasibility.

  • plate like iron particles based bidisperse magnetorheological fluid
    Journal of Applied Physics, 2013
    Co-Authors: Kruti Shah, Seungbok Choi, R V Upadhyay
    Abstract:

    Magnetorheological (MR) properties are experimentally investigated for bi-dispersion suspension of plate-like iron magnetic particles dispersed in Carrier Liquid to see the influence of small size particle on large size MR fluid. As a first step, structural, magnetic, and morphology of two different micron size magnetic particles are described in details. The three different weight fractions of MR fluid samples are then prepared, followed by measuring their magneto-viscous and visco-elastic properties. In the steady-state shear, the Bingham yield stress obtained by extrapolating the shear stress to the zero shear rate increases by augmenting the weight fraction of small micron size magnetic particles and the strength of magnetic field. In the oscillatory strain sweep test at an angular frequency of 10 rad s−1, a transition from visco-elastic solid to visco-elastic Liquid is observed and a strong chain formation is proposed to explain the mechanism for transition. The storage modulus also increases with in...

Franck Chollet - One of the best experts on this subject based on the ideXlab platform.

  • optical detection for droplet size control in microfluidic droplet based analysis systems
    Sensors and Actuators B-chemical, 2006
    Co-Authors: Namtrung Nguyen, Sumantri Lassemono, Franck Chollet
    Abstract:

    Abstract This paper reports on a hybrid polymeric microfluidic device with optical detection for droplet-based systems. The optical part of the device is integrated by a hybrid concept. The microfluidic structures were fabricated using CO 2 laser on poly methylmethacrylate (PMMA) substrate. The microfluidic network consists of two microchannels for forming droplets of an aqueous Liquid in an immiscible Carrier Liquid. The optical component consists of two optical fibers for guiding laser light from the source, through the detection point, to a photo diode. The formed droplets pass the detection point and diffract the incoming laser light. The detected signal at the photo diode can be used for evaluating droplet size, droplet shape, and droplet formation frequency. The device can detect very high formation frequencies, which are not detectable using a conventional CCD camera/microscope setup.

  • optical detection for droplet size control in microfluidic droplet based analysis systems
    International Conference on Solid-State Sensors Actuators and Microsystems, 2005
    Co-Authors: Namtrung Nguyen, Sumantri Lassemono, Franck Chollet
    Abstract:

    We report for the first time a hybrid polymeric microfluidic device with optical detection for microfluidic droplet-based systems. The device consists of a fluidic part and an optical part. Microchannels were fabricated using CO/sub 2/ laser. The microfluidic part consists of two microchannels for forming droplets of an aqueous Liquid in an immiscible Carrier Liquid. The optical part consists of two optical fiber for light emission and light detection. Microdroplets are formed, when the aqueous Liquid is injected into the Carrier flow. The formed bubbles pass the optical detection and diffract some of the incoming light. The detected signal from the other optical fiber can be evaluated for droplet size, droplet shape, and droplet formation frequency.

Kruti Shah - One of the best experts on this subject based on the ideXlab platform.

  • the influence of particle size on the rheological properties of plate like iron particle based magnetorheological fluids
    Smart Materials and Structures, 2015
    Co-Authors: Kruti Shah, Seungbok Choi
    Abstract:

    This work is devoted to the dependence of particle size on magnetorheological properties of magnetorheological fluid (MRF) consisting of plate-like iron particles suspended in a Carrier Liquid with two aspects. One aspect is to study the influence of the particle size on the rheological properties of the MRF, and the other is to investigate the influence of small-sized particles on the large-sized MRF. In order to achieve this goal, firstly, two different types of MR suspensions have been constituted by a plate-like iron particle; one is small with an average particle size of 2 μm in diameter, and the other is large with an average particle size of 19 μm in diameter. In this work, these are denoted as S-MRF and L-MRF, respectively. Secondly, in order to check the influence of the small particle size of the large-sized MR fluid, three different weight fractions of bidisperse MRF samples are prepared. The structural and morphology of plate-like iron particles are described in detail. The magnetic properties of these MR fluids are carried out at room temperature using the magnetometer, followed by the investigation on the field-dependent rheological properties of these MR fluids. It is observed that in both the S-MRF and L-MRF, the yield stress and viscosity is increased by the increasing particle size, which directly shows a correlation with the fluid magnetization. It is also identified from the test of the bidisperse MRF samples that the yield and viscosity depend on the weight fraction due to the magnetostatic interaction between the two different sizes of particles. Based on the rheological properties, some figures of merit are derived for the proposed MRF samples, which are important in the design of the application device. The sedimentation experiments for MRF samples are performed to check the stability of the MRF each day. With the basic rheological properties and sedimentation experiments, it is clearly demonstrated that the bidisperse MR suspension with a precise weight fraction has high yield stress and low sedimentation stability, which shows practical feasibility.

  • plate like iron particles based bidisperse magnetorheological fluid
    Journal of Applied Physics, 2013
    Co-Authors: Kruti Shah, Seungbok Choi, R V Upadhyay
    Abstract:

    Magnetorheological (MR) properties are experimentally investigated for bi-dispersion suspension of plate-like iron magnetic particles dispersed in Carrier Liquid to see the influence of small size particle on large size MR fluid. As a first step, structural, magnetic, and morphology of two different micron size magnetic particles are described in details. The three different weight fractions of MR fluid samples are then prepared, followed by measuring their magneto-viscous and visco-elastic properties. In the steady-state shear, the Bingham yield stress obtained by extrapolating the shear stress to the zero shear rate increases by augmenting the weight fraction of small micron size magnetic particles and the strength of magnetic field. In the oscillatory strain sweep test at an angular frequency of 10 rad s−1, a transition from visco-elastic solid to visco-elastic Liquid is observed and a strong chain formation is proposed to explain the mechanism for transition. The storage modulus also increases with in...