A particle flow specific boundary element formulation for microfluidic applications

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.In this study, a special formulation to obtain velocities of particles flowing within a microchannel is presented. The formulation is based on boundary element method, and the large system matrices resulting from the analysis is reduced to a system of linear equations with the unknowns being the rigid-body motion parameters of the particles. This reduction is achieved through matrix multiplications which increases computational efficiency when compared with the solution of a large system of equations. Since the formulation involves mainly matrix multiplications, parallelization is straightforward. With the presented algorithm, only the position of the particle(s) are tracked through the solution of their rigid-body velocities and an explicit time integration to obtain displacements. Due to the boundary-only nature of the boundary element method, the particle flow in close proximity to the channel walls are very effectively modeled without any need for specific model. The presented method is given in 2D, where the 3D formulation is straightforward. To demonstrate the applicability of the method, besides some benchmark problems, two fundamental processes, namely flow cytometry and hydrodynamic-based particle separation, are studied. It is observed that present formulation offers an efficient numerical model to be used for the simulation of the particle trajectory for 2D microfluidic applications and can easily be extended for 3D multiphysics simulations

Modeling of on-chip (bio)-particle separation and counting using 3D electrode structures

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.In lab-on-a-chip applications, manipulation and quantification of (bio)particles is required in a variety of biomedical applications such as drug screening, disease detection and treatment. For manipulation of particles, electrical techniques such as dielectrophoresis (DEP) is very suitable. For the quantification or counting of the bioparticles, flow cytometer, fluorescence-activated cell sorting (FACS) and magneticactivated cell sorting (MACS) are common techniques. In this study, modeling of microfluidic (bio)-particle separation based on dielectrophoresis and counting based on capacitance measurement using COMSOL Multiphysics have been presented. The device performance with planar and 3D electrode structures have been compared. Microfluidic devices with an asymmetric pair (for separation) and a symmetric pair (for counting) of electrodes are considered. The effects of the geometrical parameters, material properties, flow rate, particle size and applied voltage on the device performance have been discussed. The fabrication procedure of 3D electrode structures is also addressed

Macrofungal diversity of Bolu Abant Nature Park (Turkey)

This study was based on materials of macrofungi collected from Bolu Abant Nature Park between 2008 and 2009. As a result of field and laboratory studies, 103 taxa belonging to 34 families were identified. Five (5) taxa belong to Ascomycota and 98 to Basidiomycota

Effect of sage extract (Salvia officinalis) on growth performance, blood parameters, oxidative stress and DNA damage in partridges

This study was performed to evaluate the effect of different doses of sage extract on the growth and blood parameters, oxidative stress and DNA damage in partridges. In total, 252 day-old partridges (Alectoris chukar) were used. The birds were divided into four groups: 0.1% flavomycin was included in the diet of the control group (I) while 2.5, 5.0 and 7.5 mL sage extract/kg were included in the diets of treatment groups II, III and IV, respectively. At the end of the experiment no significant differences between treatments were observed in live weight, live weight gain, feed consumption, feed conversion ratio, carcass weight and survival rate. In addition, blood analyses indicated that the differences between groups in the amounts of plasma cholesterol, triglyceride high density lipoprotein (HDL), very low density lipoprotein (VLDL) and alkaline phosphates (ALP) were not significantly different. Furthermore, treatments did not affect total sulphydryl (SH) and lipid hydroperoxide (LOOH) concentrations, total antioxidant response or the total oxidant status (TOS). However, sage extract significantly decreased DNA damage in a linear, dose-dependent manner whilst the antibiotic, flavomycin, elevated the oxidative stress index (OSI) and resulted in DNA damage. It was concluded that supplementing sage extract in the partridge diet at the doses studied does not lead to a negative effect on the growth performance of these birds. Keywords: Salvia officinalis, Alectoris chukar, growth performance, blood parameters, DNA damage South African Journal of Animal Science Vol. 38 (2) 2008: pp. 145-15

Evaluation of nusselt number for a flow in a microtube with second-order model including thermal creep

In this paper, Nusselt number for a flow in a microtube is determined analytically with a constant wall heat flux thermal boundary condition. The flow assumed to be incompressible, laminar, hydrodynamically and thermally fully-developed. The thermo-physical properties of the fluid are assumed to be constant. The effect of rarefaction, viscous dissipation, axial conduction, which are important at the microscale, are included in the analysis. For the implementation of the rarefaction effect, two different second-order slip models are used for the slip-flow and temperature-jump boundary conditions together with the thermal creep at the wall. Closed form solutions for the fully-developed temperature profile and Nusselt number are derived as a function of Knudsen number, Brinkman number and Peclet number. Copyright © 2012 by ASME

Effect of Dietary Oregano and Rosemary Essential Oil Supplementation on Growth Performance and Cecal Microbiota of Broilers

In this study, the effect of dietary supplementation of oregano and rosemary essential oils (EO) on growth performance and cecal microbiota of broilers were investigated. A total of 450 1-d-old male Ross-308 broilers were divided into 5-experimental groups (10 replicates of 9 chickens): a Control (C), fed a basal diet; four treatments, which received a basal diet supplemented with oregano and rosemary EOs individually (O, 300 mg/kg oregano EO; R, 300 mg/kg rosemary EO) and combined (OR1, 150 mg/kg oregano EO + 150 mg/kg rosemary EO; OR2, 200 mg/kg oregano EO + 200 mg/kg rosemary EO). Body weight (BW), feed intake (FI), body weight gain (BWG), feed conver-sion ratio (FCR), and cecal microbiota (coliforms, clostridia and lactobacilli) were determined weekly, and at 42 d, re-spectively. BW in R (p < 0.05) and OR2 (p < 0.001), and BWG and FCR in OR2 (p < 0.05) were significantly higher than C at 42 d, despite no difference in FI in any group during experimental period. Counts of cecal coliforms (p < 0.001) and clostridia (p < 0.01) decreased, and lactobacilli (p < 0.001) increased substantially between C and treatment groups. Results indicated that combined oregano and rosemary EO (200 mg/kg ea) supplementation significantly increased BW and BWG, improved FCR in 1-42 d, lowered coliform and clostridial, and increased lactobacilli counts suggesting a beneficial shift in cecal microbiota.Bursa Uludag Uni-versity Scientific Research Unit Grant [HDP (V) -2014/45]ACKNOWLEDGEMENT This study was funded by the Bursa Uludag Uni-versity Scientific Research Unit Grant, Project No: HDP (V) -2014/45

Modeling of electro-kinetic motion of Janus droplet

Electro-kinetic manipulation Janus particles and droplets has attracted attention in recent years due to their potential application in microfluidics. Due to the presence of two different zone on the surface of particles with different charge distribution, the motion of the Janus particles are quite different than the that of regular particles. Therefore; the fundamental understanding of this motion is the key element for the further development of the microfluidic systems with Janus particles. In present study, electro-kinetic motion of Janus droplets inside a micro-channel is modeled using boundary element formulation. 2D formulation is verified against the reported experimental data in the literature. Results show that the 2D boundary element formulation is successful for the prediction of the electrophoretic velocity of the Janus droplets. The current formulation has a potential to model non-spherical particles and to study particle-particle and particle-wall interactions. © 2017 ASME The American Society of Mechanical Engineers

Historical and Geographical Information about the Exploration of the Caspian Sea in Cartographic Materials

The article provides a brief overview of the historical and geographical data on the Caspian Sea and traces the change in the name of the sea at different stages of history. The study is based on the work of scientists from Russia, Azerbaijan and Kazakhstan. The purpose of the work was to reveal the reasons for the change of sea names and the history of the formation of the marine scientific map in connection with the expeditions organized by Peter the Great in the early 18th century. The authors analyzed historical research and made an attempt to systematize cartographic materials and data from antiquity, the Middle Ages and modern times. The history of the Caspian and its adjacent territories has been a subject of debate since the time of Greek logographers in the ancient world, and historical research of the Caspian Sea continues to the present day. Since ancient times, the Caspian coast has been inhabited by many peoples, becoming a crossroads for the interaction of various cultures; in the late Middle Ages, the Caspian Sea played an important role, being located along the world trade transit known as the Great Silk Road. In the new era, competition for control over the Caspian Sea between states intensified, but as a result of the military-political actions of Peter I, the sea became a de facto geographical object of the Russian Empire, and then the Soviet Union. However, after the collapse of the USSR at the end of the 20th century, the Caspian Sea, which has a geographically convenient location and rich resources, reappeared on the historical arena as one of the most important geopolitical issues. Copyright © 2022 by Cherkas Global Universit

Modeling of Joule heating and convective cooling in a thick-walled micro-tube

The heating of a fluid in a metallic micro-tube can be realized at the inlet and/or within a certain section of micro-scale heat and fluid flow devices by using Joule heating which is a heat generation mechanism that occurs when an electric current is passed through the metallic wall. For the thermal analysis of fluid flow in an electrically heated micro-tube, the solution of conjugate heat transfer (to include effect of the axial conduction through the channel wall) together with Joule heating is required. An analytic solution is presented for conjugate heat transfer in an electrically-heated micro-tube in this study. The solution is obtained in the form of integrals by the method of Green's functions for the hydrodynamically fully-developed flow of a constant property fluid in a micro-tube. The current analytical model can predict the fluid temperature for a given wall thickness, wall material and applied voltage across the micro-tube. The effects of the wall thickness and the wall material on the normalized temperature distribution and the effectiveness parameter are discussed. The comparison of the normalized temperature for Joule heating and a spatially uniform heating is also presented. © 2017 Elsevier Masson SA

Dielectrophoresis in microfluidics technology

Dielectrophoresis (DEP) is the movement of a particle in a non-uniform electric field due to the interaction of the particle's dipole and spatial gradient of the electric field. DEP is a subtle solution to manipulate particles and cells at microscale due to its favorable scaling for the reduced size of the system. DEP has been utilized for many applications in microfluidic systems. In this review, a detailed analysis of the modeling of DEP-based manipulation of the particles is provided, and the recent applications regarding the particle manipulation in microfluidic systems (mainly the published works between 2007 and 2010) are presented. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim