武居 昌宏

Red blood cells (RBCs) aggregability AG of coagulating blood in extracorporeal circulation system has been investigated under the condition of pulsatile flow. Relaxation frequency fc from the multiple-frequency electrical impedance spectroscopy is utilized to obtain RBCs aggregability AG. Compared with other methods, the proposed multiple-frequency electrical impedance method is much easier to obtain non-invasive measurement with high speed and good penetrability performance in biology tissues. Experimental results show that, RBCs aggregability AG in coagulating blood falls down with the thrombus formation while that in non-coagulation blood almost keeps the same value, which has a great agreement with the activated clotting time (ACT) fibrinogen concertation (Fbg) tests. Modified Hanai formula is proposed to quantitatively analyze the influence of RBCs aggregation on multiple-frequency electrical impedance measurement. The reduction of RBCs aggregability AG is associated with blood coagulation reaction, which indicates the feasibility of the high speed, compact and cheap on-line thrombus measurement biosensors in extracorporeal circulation systems.

This paper investigated the influence of particle size on the exit effect of a full-scale rolling circulating fluidized bed (CFB) by using the Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) method. The gas–solid two-phase flow of the full-scale rolling CFB was compared with that of a simplified rolling CFB. Thus, the exit effect of the full-scale rolling CFB was clarified. In the air phase, a peak of air axial velocity vya was observed when the full-scale rolling CFB reached the maximum angular displacement. The particle phase possessed back mixing and radial exchange phenomena at the top and bottom of the full-scale rolling CFB, respectively. However, those phenomena were not obvious at the top and bottom of the simplified rolling CFB. The mechanism of the above-mentioned exit effect was then clarified by analyzing the forces acting on the particles under different particle sizes. Finally, the increases in particle size lead to the intensification of the peak of vya, particle back mixing, and radial exchange phenomena. Therefore, the intensity of the exit effect of the gas–solid two-phase flow increased as the particle size increased. The results suggested that the small particles had the potential to promote the purification rate of the full-scale rolling CFB on account of its small exit effect.

Contact impedance has an important effect on micro electrical impedance tomography (EIT) sensors compared to conventional macro sensors. In the present work, a complex contact impedance effect ratio ξ is defined to quantitatively evaluate the effect of the contact impedance on the accuracy of the reconstructed images by micro EIT. Quality of the reconstructed image under various ξ is estimated by the phantom simulation to find the optimum algorithm. The generalized vector sampled pattern matching (GVSPM) method reveals the best image quality and the best tolerance to ξ. Moreover, the images of yeast cells sedimentary distribution in a multilayered microchannel are reconstructed by the GVSPM method under various mean magnitudes of contact impedance effect ratio vξv. The result shows that the best image quality that has the smallest voltage error UE = 0.581 is achieved with measurement frequency f = 1 MHz and mean magnitude vξv = 26. In addition, the reconstructed images of cells distribution become improper while f &lt 10 kHz and mean value of vξv &gt 2400.

Copyright © (2018) by Chemical and Biological Microsystems Society. All rights reserved. A novel electrical impedance tomography (μEIT) method for cell visualization with recognition of living yeast cell (L-yeast) and dead yeast cell (D-yeast) is proposed. The proposed method combines μEIT with electrical impedance spectroscopy in order to visualize the L-yeast and D-yeast cell condition which cannot be considered in conventional μEIT. Also, in experiment two wire measurement method is applied instead of conventional 4 wire measurement method in order to eliminate the noise. As an experimental result, the spatial distribution of L-yeast and D-yeast in microchannel was successfully visualized with low noise.

© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Microfluidic device embedding electrodes realizes cell manipulation with the help of dielectrophoresis. Cell manipulation is an important technology for cell sorting and cell population purification. Till now, the theory of dielectrophoresis has been greatly developed. Microfluidic devices with various arrangements of electrodes have been reported from the beginning of the single non-uniform electric field to the later multiple physical fields. This paper reviews the research status of microfluidic device embedding electrodes for cell manipulation based on dielectrophoresis. Firstly, the working principle of dielectrophoresis is explained. Next, cell manipulation approaches based on dielectrophoresis are introduced. Then, different types of electrode arrangements in the microfluidic device for cell manipulation are discussed, including planar, multilayered and microarray dot electrodes. Finally, the future development trend of the dielectrophoresis with the help of microfluidic devices is prospected. With the rapid development of microfluidic technology, in the near future, high precision, high throughput, high efficiency, multifunctional, portable, economical and practical microfluidic dielectrophoresis will be widely used in the fields of biology, medicine, agriculture and so on.

The distinct motion of GFP-tagged histone expressing cells (Histone-GFP type cells) has been investigated under ac electrokinetics in an electrode-multilayered microfluidic device as compared with Wild type cells and GFP type cells in terms of different intracellular components. The Histone-GFP type cells were modified by the transfection of green fluorescent protein-fused histone from the human lung fibroblast cell line. The velocity of the Histone-GFP type cells obtained by particle tracking velocimetry technique is faster than Wild type cells by 24.9% and GFP type cells by 57.1%. This phenomenon is caused by the more amount of proteins in the intracellular of single Histone-GFP type cell than that of the Wild type and GFP type cells. The more amount of proteins in the Histone-GFP type cells corresponds to a lower electric permittivity ϵ c of the cells, which generates a lower dielectrophoretic force exerting on the cells. The velocity of Histone-GFP type cells is well agreed with Eulerian-Lagrangian two-phase flow simulation by 4.2% mean error, which proves that the fluid motion driven by thermal buoyancy and electrothermal force dominates the direction of cells motion, while the distinct motion of Histone-GFP type cells is caused by dielectrophoretic force. The fluid motion does not generate a distinct drag motion for Histone-GFP type cells because the Histone-GFP type cells have the same size to the Wild type and GFP type cells. These results clarified the mechanism of cells motion in terms of intracellular components, which helps to improve the cell manipulation efficiency with electrokinetics.

An electrical impedance spectro-tomography consists of a quasi-adjacent sensing method and a frequency-time difference imaging for relatively complex dielectric object monitoring has been proposed. A quasi-adjacent sensing method is designed to measure an electrical impedance spectroscopy based on four-wire measurement technique at the multi-electrodes electrical impedance tomography sensor. A frequency-time difference imaging for spatial distribution monitoring is needed, as the electrochemical reaction incur during the short time meanwhile the spatial geometry tends to be constant. An artificial set of phantoms were made and the proposed technique was capable to show the Cole-Cole parameters as a dielectric relaxation model on each measurement pair. Compare with the adjacent method, using the quasi-adjacent method show Re(Z) is two times higher, Imag(Z) is ten times higher, and a higher and homogeneous sensitivity map area are 60% wider. A negative resistance at high-frequency measurement also can be eliminated successfully by using the proposed method.

This paper reviews the latest development and emerging technologies on the application of process tomography to multiphase flow measurement in industrial and biomedical fields. In the industrial applications, electrical resistance tomography and electrical capacitance tomography are popularly applied in multiphase flow measurement dependent on the electrical properties of the objects. In particular, applications to circulating fluidized bed, trickle-bed reactor and temperature measurement are discussed. In the biomedical applications, in most cases, measurement is conducted in a static condition. Two latest applications in flowing condition are reviewed, which are thrombus detection in blood flow and cell sensing with a microfluidic device. Finally, the challenges to process tomography for multiphase flow measurement on industrial and biomedical applications are addressed.

A nonlinear normalization model which is called exponential model for electrical capacitance tomography (ECT) with external electrodes under gap permittivity conditions has been developed. The exponential model normalization is proposed based on the inherently nonlinear relationship characteristic between the mixture permittivity and the measured capacitance due to the gap permittivity of inner wall. The parameters of exponential equation are derived by using an exponential fitting curve based on the simulation and a scaling function is added to adjust the experiment system condition. The exponential model normalization was applied to two dimensional low and high contrast dielectric distribution phantoms by using simulation and experimental studies. The proposed normalization model has been compared with other normalization models i.e. Parallel, Series, Maxwell and Bottcher models. Based on the comparison of image reconstruction results, the exponential model is reliable to predict the nonlinear normalization of measured capacitance in term of low and high contrast dielectric distribution.

A Cole-Cole analysis of electrical impedance of blood was performed to explore the possibility of monitoring thrombus formation in extracorporeal blood circulation. Thrombus formation experiments were conducted in both static and flowing conditions by changing the coagulability of the bovine and swine blood. Among the four Cole-Cole parameters which are the relaxation frequency f(c), the resistance at zero frequency R-0, the resistance at infinite frequency R-infinity, shape factor a, the relaxation frequency f(c) first increased, reached to the characteristic peak and then decreased during thrombus formation. Other Cole Cole parameters were either monotonically increasing or decreasing throughout the time without any characteristic point. Additionally, change of pattern followed the same increasing/decreasing pattern for all red blood cells (RBCs) concentrations. Simulations were made on the basis of Hanai's mixture formula to evaluate the results. On the basis of evaluation, the peak time is considered as the time to form the RBCs aggregation. Hence, the monitoring of the relaxation frequency f(c) is the appropriate strategy form thrombus detection. It provides the possibility of visualizing thrombus formation based on the single tomographic image of relaxation frequency distribution instead of multiple tomographic images of impedance at various frequencies in multifrequency electrical tomography. (C) 2016 Elsevier Ltd. All rights reserved.

Cell migration is an important process both in physiological and pathological conditions. Migrating cells in vivo respond to various extracellular environmental factors and change their migratory behavior. Thus, it is important to take into account extracellular environmental factors in studies on cell migration. This study specifically focused on fibroblast migration in a three-dimensional microenvironment. We fabricated a polydimethylsiloxane cell culture substrate with intersecting grooves as a model to mimic a feature of the complex porous microenvironment experienced by fibroblasts in vivo. The sizes of the grooves allowed fibroblasts to penetrate into the grooves. The effects of branched grooved structures on cell migration, and on cellular organization of the actin filaments and phosphorylated myosin light chain, were analyzed. Fibroblasts migrated along intersecting lattice grooves that were 5 μm wide, 13 μm deep, and spaced 10 μm apart. Analysis of the cellular distribution of actin filaments and phosphorylated myosin light chain demonstrated two effects of the intersecting grooved structure on actin cytoskeletal organization in the fibroblast. One was the enhancement of filopodia protrusions into the branched groove at the junction, and the other was the formation of stress fibers to cross the opening of the junction. These results suggest that the filopodia protrusions are guided by the groove and are followed by the cytoplasmic protrusion, then the rear of the cell retracts due to stress fiber contraction, leading to fibroblast guided migration in the branched intersecting groove.

A10-parameter Electrical Equivalent Circuit (10-parameter EEC) has been proposed to evaluate the electrochemical characterizations which are resistance, reactance and relaxation frequency of Lithium-ion battery (LIB) slurry under different components weight ratio of three samples composed of PVDF-NMP solution, Carbon Black (CB) absent slurry and CB present slurry. The 10-parameter EEC is constructed by combining the internal structure of LIB slurry and the electrochemical responses of three samples. Four conclusions are clarified by fitting Electrochemical Impedance Spectroscopy (EIS) Nyquist and Bode plots with the 10-parameter EEC. Firstly, the standard deviation S of the 10-parameter EEC < S10-p> = 14.3% is lower than that of a conventional 8-parameter EEC < S8-p> = 30.6% by Delta S = 16.3%. Secondly, the resistance of electric double layer (EDL) R-dl is firstly increased and then decreased as LiCoO2 particles weight ratio wtLiCoO(2) is increased, which is well explained by LiCoO2-PVDF ratio effect. Thirdly, the resistances of PVDF-NMP solution RSO and conductive path Rp are the resistances of LiCoO2-NMP interface dispersion and PVDF-NMP solution dispersion in LIB slurry. Lastly, relaxation frequencies of LiCoO2-NMP interface dispersion f(relax, high) and PVDF-NMP solution dispersion f(relax, low) obtained from EIS experiment can be represented by those of f(relax1) and f(relax2) calculated from the 10-parameter EEC. (C) 2016 The Electrochemical Society.

Themorphological structure characterizations of Lithium-ion battery (LIB) slurry have been clarified under shear rotational conditions of rotation speed n and rotation time t by on-line dynamic electrical impedance spectroscopy (EIS) method. The EIS Nyquist and Bode plots are fitted by 10-parameter electrical equivalent circuit (10p-EEC) to clarify electrochemical characteristics which are resistance, reactance and peak frequency of LIB slurry. Then, the on-line dynamic resistance of conductive path R-p, the time-averaged capacitances of PVDF-CB double layer C-dl and PVDF-NMP solution C-SO are obtained, which results in the following morphological structure characterizations of LIB slurry. The network structure of LIB slurry is deteriorated in the low rotation speeds of n = 50 rpm and n = 150 rpm and is well constructed in the high rotation speeds of n = 300 rpm and n = 720 rpm. Moreover, PVDF-CB double layer is well formed with the increase of n. Furthermore, with the increase of t, the particle size of LiCoO2 coated by CB is slightly changed in the low rotation speeds of n = 50 rpm and of n = 150 rpm; however, the particle size of LiCoO2 coated by CB is increased in the high rotation speeds of n = 300 rpm and n = 720 rpm. The above-mentioned morphological structure characterizations are in agreement with those observed from morphological images of LIB slurry. (C) 2017 The Electrochemical Society. All rights reserved.

The effect of rolling amplitude and rolling period on particle distribution behaviors in a rolling circulating fluidized bed (RCFB) has been quantitatively clarified by means of the electrical capacitance tomography (ECT) technique. A series of experiments with a cold mode RCFB were performed while the rolling amplitude and rolling period varied from Theta = 2.5 degrees to 10.0 degrees and T = 5.0 to 15.0 s, respectively. Based on the particle distribution images captured by the ECT sensor, three main characteristics of particle distribution behavior, namely the average particle volume fraction, the particle distribution stability and the particle distribution uniformity, were quantitatively estimated. As results, the particle distribution behavior in the RCFB was dominated by the shear effect, which was derived from the inertial forces and gravity in the radial direction of the riser. The positive influence of rolling amplitude on the shear effect caused augmentation of the particle volume fraction; however, particle distribution became unstable and heterogeneous. Meanwhile, although the characteristic fluctuation frequency of particle volume fraction was dominated by the rolling period, little effect of the rolling period on the particle distribution behaviors was observed due to its minimal influence on the shear effect. (C) 2016 Elsevier B.V. All rights reserved.

An optical transparent 3-D Integrated Microchannel-Electrode System (3-DIMES) has been developed to understand the particles' movement with electrokinetics in the microchannel. In this system, 40 multilayered electrodes are embedded at the 2 opposite sides along the 5 square cross-sections of the microchannel by using Micro Electro-Mechanical Systems technology in order to achieve the optical transparency at the other 2 opposite sides. The concept of the 3-DIMES is that the particles are driven by electrokinetic forces which are dielectrophoretic force, thermal buoyancy, electrothermal force, and electroosmotic force in a three-dimensional scope by selecting the excitation multilayered electrodes. As a first step to understand the particles' movement driven by electrokinetic forces in high conductive fluid (phosphate buffer saline (PBS)) with the 3-DIMES, the velocities of particles' movement with one pair of the electrodes are measured three dimensionally by Particle Image Velocimetry technique in PBS; meanwhile, low conductive fluid (deionized water) is used as a reference. Then, the particles' movement driven by the electrokinetic forces is discussed theoretically to estimate dominant forces exerting on the particles. Finally, from the theoretical estimation, the particles' movement mainly results from the dominant forces which are thermal buoyancy and electrothermal force, while the velocity vortex formed at the 2 edges of the electrodes is because of the electroosmotic force. The conclusions suggest that the 3-DIMES with PBS as high conductive fluid helps to understand the three-dimensional advantageous flow structures for cell manipulation in biomedical applications. (C) 2016 AIP Publishing LLC.

The inertial migration of neutrally buoyant spherical particles in high particle concentration (alpha(pi)>3%) suspension flow in a square microchannel was investigated by means of the multi-electrodes sensing method which broke through the limitation of conventional optical measurement techniques in the high particle concentration suspensions due to interference from the large particle numbers. Based on the measured particle concentrations near the wall and at the corner of the square microchannel, particle cross-sectional migration ratios are calculated to quantitatively estimate the migration degree. As a result, particle migration to four stable equilibrium positions near the centre of each face of the square microchannel is found only in the cases of low initial particle concentration up to 5.0 v/v%, while the migration phenomenon becomes partial as the initial particle concentration achieves 10.0 v/v% and disappears in the cases of the initial particle concentration alpha(pi)>= 15%. In order to clarify the influential mechanism of particle-particle interaction on particle migration, an Eulerian-Lagrangian numerical model was proposed by employing the Lennard-Jones potential as the inter-particle potential, while the inertial lift coefficient is calculated by a pre-processed semi-analytical simulation. Moreover, based on the experimental and simulation results, a dimensionless number named migration index was proposed to evaluate the influence of the initial particle concentration on the particle migration phenomenon. The migration index less than 0.1 is found to denote obvious particle inertial migration, while a larger migration index denotes the absence of it. This index is helpful for estimation of the maximum initial particle concentration for the design of inertial microfluidic devices. Published by AIP Publishing.

Prediction of rupture status in cerebral aneurysms remains challenging for clinicians, and the important rupture indicator (wall shear stress, WSS) is controversially discussed. Recent studies report that flow instabilities appear to play an influential role in the evolution and rupture of aneurysms and it is strongly correlated with both geometries and inlet flow rate waveforms. However, how frequency harmonics in inlet flow rate waveforms influence the flow instabilities and hence WSS fluctuations in cerebral aneurysms are still unclear. In this study, we used a computational fluid dynamic (CFD) model of anatomically realistic cerebral aneurysms combining with Fourier series and power spectral density (PSD) analysis to investigate the association between inflow waveform's harmonic frequencies and flow fluctuations in terminal cerebral aneurysms. Our simulated results demonstrated that there exists a harmonic frequency dependency in inlet flow rate waveforms inherently associated with flow instabilities in cerebral aneurysms: low-frequency harmonics play a crucial role in causing significant WSS fluctuations. This is partly explained by that the low-frequency harmonics govern a primary local adverse pressure gradient at late systole during flow deceleration, which induces flow instabilities while giving it sufficient time to develop into flow instabilities whereas high-frequency harmonics do not but decay rapidly. This implies that flow fluctuations in cerebral aneurysms may be of some robustness, dependent mainly on the primary harmonic frequency initiated by heart contraction but against unpredictable high-frequency perturbations in the inflow waveforms.

This study has launched a concept to measure real time two-dimensional temperature distribution non-invasively by a combination of electrical capacitance tomography (ECT) technique and a permittivity-temperature equation for plastic pellets. The concept has two steps which are the relative permittivity calculation from the measured capacitance among the many electrodes by ECT technique, and the temperature distribution calculation from the relative permittivity distribution by permittivity-temperature equation. ECT sensor with 12-electrode is designed to measure and visualize the cross sectional temperature distribution during polymethyl methacrylate (PMMA) pellets cooling process. The images of the normalized relative permittivity distribution are successfully reconstructed at every time step during the process. The images indicate that the normalized relative permittivity of PMMA pellets is decreased as the temperature is decreased.

Cell movement plays an essential role in embryonic development, wound healing in multicellular organisms and cancer metastatis. It is known to be a cyclic system of the protrusion at the leading edge, adhesion to the extracellular matrix via focal adhesions and detachment and retraction at the cell rear. Focal adhesions are one of the key players for cell movement. However, in case of HT1080 fibrosarcoma cell which is one of the cancer cells, although mechaism of invasion to the extracellular matrix has been extensively studied, mechanism of adhesion to the extracellular matrix via focal adhesions has not been well understood. In this study, therefore, an attemp was made to visualize and analyze the distribution of focal adhesions in HT1080 fibrosarcoma cells expressing RFP-zyxin and GFP-actin by laser confocal microscopy. As a result, during movement of HT1080 fibrosarcoma cell, focal adhesions appeared at the region of protrusion whereas they disappeared or remained at the region of retraction, which led to the asymmetric distribution of focal adhesions in the cell. On the other hand, when a cell showed staying behavior during movement, focal adhesions equally distributed close to the edge of the cell.

<p>The thrombus existence is an important criterion in the Judgment of circulatory system diseases and the development of circulator organ device. In this study, the possibility of thrombus detection using electrical measurements was explore.Electrical measurement of thrombus formation process was carried out in a circulation. Swine blood was coagulated by the addition of 0.02M calcium chloride solution. Impedance between two stainless rings attached to the circulation was measured 120 minutes to determine the relaxation frequency by Cole-Cole analysis. The ACT was measured every 20 minutes.Relaxation frequency increases initially and reaches a peak at 85 minutes. The ACT were less than 100 near 85 minutes. It is presumed that influence of the thrombus formation is strong after the peak.Since the peak of the relaxation frequency appeared in thrombus formation process, the possibility of thrombus detection using the peak of the relaxation frequency is shown.</p>

This study has launched a concept to image a real-time 2D temperature distribution noninvasively by a combination of the electrical capacitance tomography (ECT) technique and a permittivity-temperature calibration equation for the plastic pellet cooling process. The concept has two steps, which are the relative permittivity calculation from the measured capacitance among the many electrodes by the ECT technique, and the temperature distribution imaging from the relative permittivity by the permittivity-temperature calibration equation. An ECT sensor with 12 electrodes was designed to image the cross-sectional temperature distribution during the polymethyl methacrylate pellets cooling process. The images of temperature distribution were successfully reconstructed from the relative permittivity distribution at every time step during the process. The images reasonably indicate the temperature diffusion in a 2D space and time within a 0.0065 and 0.0175 time-dependent temperature deviation, as compared to an analytical thermal conductance simulation and thermocouple measurement.

© 2016, Copyright © Taylor &amp; Francis Group, LLC. Three electrical elements (i.e., resistance, capacitance, and relaxation frequency) of electrical double layer (EDL) formed around particles have been extracted by a measuring–fitting combination for a novel noninvasive online measurement technique of particle size and concentration in a liquid–particle mixture. The measuring–fitting combination means measuring the impedances with electrical-impedance spectroscopy (EIS) method, and fitting the equivalent circuit with Levenberg–Marquardt method. The liquid–particle mixture in the impedance measurement is made of sodium chloride solution and stainless particles; the equivalent circuit is established corresponding to the contents in the liquid–particle mixture. As a result, the influence of the particle size and concentration on the electrical elements in the EDL which are the resistance, capacitance, and relaxation frequency in the EDL are clarified and discussed. This method is useful for determination of the particle size and concentration in liquid–particle mixture.

The relative permittivity epsilon' and the dielectric loss epsilon aEuro(3) for various hematocrit values H for static bovine blood condition have been measured using the dielectric relaxation method to detect thrombosis in real time. The suitable measurement frequency f (m) ranged within 60 kHz to 1 MHz, and the relaxation frequency of red blood cells (RBCs) f (rc) was observed to be 2 MHz. In the f (m), the temporal change of normalized epsilon' exhibited a minimum (called as bottom point). The bottom point was observed to be exponentially shortened as H increased. This characteristic of the epsilon'* minimum is discussed from three viewpoints: during fibrin formation, direct thrombus formation, and rouleaux formation processes. epsilon'* during the fibrin formation process decreased over time, irrespective of f. However, epsilon'* in f (m) during the direct thrombus formation process and during the aggregation formation process increased immediately and rapidly over time. Therefore, the epsilon'* bottom point in f (m) might be the indication of micrometer-scale thrombus formation by RBC aggregation due to fibrin formation.

Visualization of a thrombus is very important in the development of various artificial organs and extracorporeal circulation devices. This paper presents an application of electrical resistance tomography (ERT) technique for the visualization of a thrombus in blood. Experiments were conducted in static and flowing bovine and swine blood samples. Artificially created thrombi were mixed in the blood samples for visualization. Eight-electrode tomography sensor was used for the measurement. Cross-sectional resistivity distribution was reconstructed using linear back projection algorithm. A thrombus was characterized by increased local resistivity. We successfully reconstructed the time, size and cross-sectional location of a thrombus, and reached a conclusion that the concentration and orientation of the RBCs in a thrombus contributed to the increase in the resistivity. The increment was relatively higher in the static blood than in flowing blood. These findings can be helpful in the development of an instrumentation system for the real-time monitoring of blood to visualize a thrombus. Developers of left ventricular assistance devices, heart-lung machines, hemodialyzer etc., and the end-users (i.e. patients) can greatly benefit from such a system. (C) 2015 Elsevier Ltd. All rights reserved.

Physical value of dielectric properties among relative permittivity, dielectric loss and loss tangent of mixed melting polymer pellets were measured under temperature variance condition and measurement frequency from 0.5 MHz to 5 MHz in order to develop a real-time non-intrusive measurement technique for high performance waste plastic separation. Various volume fractions of non-polar polyethylene (PE) and polar polyethylene terephthalate (PET) were used as the mixed polymer pellets. As the results, with the volume fractions of PET from 0.05 to 0.22, as the temperature is increased up to melting point temperature and above mold temperature, the relative permittivity is decreased as the temperature is increased. However over melting temperature up to the mold temperature, the relative permittivity is slightly increased as the temperature is increased. On the other hand, the dielectric loss and loss tangent are not affected by the temperature variance, and the dielectric loss and loss tangent are increased as the measurement frequency is increased. As the conclusions, at molding temperature 180 degrees C (453 K), the highest sensitivity of dielectric property is the relative permittivity. Meanwhile, the highest linearity relationship between PET volume fraction and predicted relative permittivity is achieved at the measurement frequency of 5 MHz. From relative permittivity measurement in these conditions, the performance to distinguish PET volume fraction 0.05 from PE volume fraction 0.95 is achieved in the mixed melting polymer pellets. Therefore, the relative permittivity measurement for waste plastic separation has a possibility to achieve the high purity recycled plastics as compared with conventional methods. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

The classical Fontan route, namely the atriopulmonary connection (APC), continues to be associated with a risk of thrombus formation in the atrium. A conversion to a total cavopulmonary connection (TCPC) from the APC can ameliorate hemodynamics for the failed Fontan; however, the impact of these surgical operations on thrombus formation remains elusive. This study elucidates the underlying mechanism of thrombus formation in the Fontan route by using a two-dimensional computer hemodynamic simulation based on a simple blood coagulation rule. Hemodynamics in the Fontan route was simulated with Navier-Stokes equations. The blood coagulation and the hemodynamics were combined using a particle method. Three models were created: APC with a square atrium, APC with a round atrium, and TCPC. To examine the effects of the venous blood flow velocity, the velocity at rest and during exercise (0.5 and 1.0 W/kg) was measured. The total area of the thrombi increased over time. The APC square model showed the highest incidence for thrombus formation, followed by the APC round, whereas no thrombus was formed in the TCPC model. Slower blood flow at rest was associated with a higher incidence of thrombus formation. The TCPC was superior to the classical APC in terms of preventing thrombus formation, due to significant blood flow stagnation in the atrium of the APC. Thus, local hemodynamic behavior associated with the complex channel geometry plays a major role in thrombus formation in the Fontan route.

Study of particle migration is important to enhance and increase the efficiency of the positioning and sorting process in order to produce the high yield of desired product especially in microfluidic applications. In this study, in order to study particle migration, normalized particle concentration in a micro-channel has been calculated for high initial particle concentrations (xi=3.0, 5.0 and 10.0%) and the small particle diameters (d(p)=1.3, 1.5 and 2.1 mu m) by using capacitance data measured by a multi-capacitance sensing method. From the calculations, it has been observed that the particle concentration at the wall vicinity area is increased as xi and d(p) are increased while the particle concentration at the center area is decreased. To analyze the tendency of the particle migration, two quantitative indicators are introduced, viz., streamwise migration ratio (psi) which is the ratio of particle concentration at the downstream to the upstream cross-section position, and the cross-sectional migration ratio (phi) which is the ratio of the particle concentration at the wall to the center area at the same cross-sectional position. The result shows that the psi at the center area is decreased as the particles move along the channel irrespective of xi and d(p) while the psi at the wall vicinity area is increased. Based on psi and phi, it has been observed that the particle migrate from the center area towards the wall vicinity area in the case of low xi and small d(p) while the particles tend to concentrate on the center area in the case of high xi and the large d(p). As a result, the particle concentration at center is higher in the case of the lower xi and the smaller d(p) than that in the case of higher xi and the larger d(p). (C) 2015 Elsevier Ltd. All rights reserved.

The spatial concentration distribution of cells in a microchannel is measured by combining the dielectric properties of cells with the specific structure of the electrode-multilayered microchannel. The dielectric properties of cells obtained with the impedance spectroscopy method includes the cell permittivity and dielectric relaxation, which corresponds to the cell concentration and structure. The electrode-multilayered microchannel is constructed by 5 cross-sections, and each cross-section contains 5 electrode-layers embedded with 16 micro electrodes. In the experiment, the dielectric properties of cell suspensions with different volume concentrations are measured with different electrode-combinations corresponding to different electric field distributions. The dielectric relaxations of different cell concentrations are compared and discussed with the Maxwell-Wagner dispersion theory, and the relaxation frequencies are analysed by a cell polarization model established based on the Hanai cell model. Moreover, a significant linear relationship with AC frequency dependency between relative permittivity and cell concentration was found, which provides a promising way to on-line estimate cell concentration in microchannel. Finally, cell distribution in 1 cross-section of the microchannel (X and Y directions) was measured with different electrode-combinations using the dielectric properties of cell suspensions, and cell concentration distribution along the microchannel (Z direction) was visualized at flowing state. The present cell spatial sensing study provides a new approach for 3 dimensional non-invasive online cell sensing for biological industry. (C) 2015 AIP Publishing LLC.

Electrical resistance tomography was applied to non invasively visualize the liquid distribution in a lab scale trickle bed reactor. Based on the three-dimensional liquid distribution images (Lime and two dimensional space) obtained by the ERT system, effect of the physical properties of the fluids and the packed bed, such as column size, particle diameter, gas density and liquid viscosity, on the pulsing flow regime transition and the liquid pulse structures were clarified. The liquid pulses structures were basically dominated by the small local pulses generated in the capillaries between the packed particles. Promotion of the local pulses generation makes the macro liquid pulses evident and well separated, while restriction of the local pulses generation results in the not fully developed or transient liquid pulses. Moreover, basic hydrodynamic parameters characterizing the pulsing flow, namely the liquid pulse velocity and frequency, were also quantitatively discussed. Liquid pulse velocities were calculated by the cross correlation of the conductivity variations of two ERT sensor with certain distance. The effective liquid pulse frequency which only includes the contribution of the main liquid pulse was determined by identified number of main liquid pulse from the 3D liquid distribution images provided by ERT. The measured liquid pulse velocity and frequency by ERT were then compared with the correlation models proposed in previous literatures. (C) 2015 Elsevier Ltd. All rights reserved.

Flow characteristics inside a cyclone filter were investigated by the use of computational fluid dynamics (CFD). For computations, SST model was adopted. Parametric study was carried out considering the filtering performance. Revolution speeds were changed from 100 to 550 with 50 increments. A skirt is the driving source for cyclone operation. The influence of several design factors, such as the skirt length, the skirt gap and the return length to filtering performance was investigated under the particle diameter 100 mu m of debris material (Al, s.g.=2.7). The filtering performance was also investigated with the skirt length 28mm changing the debris diameters from l mu m to 50 mu m. The flow rate of the working fluid was maintained at 0.55kg/s. It has been verified that the most influential factors to the filtering efficiencies was the skirt gap between the cyclone generator and the cyclone vessel.

Tomography is an effective method for imaging, separating, or sorting of cells. In this chapter, a condensed review of recent advances accomplished in development and applications of noninvasive tomographic techniques to multiphase flows is presented. In recent years, utilization of such noninvasive techniques has become widespread in engineering disciplines, dealing with systems involving two immiscible phases or more. Tomography provides concentration, holdup, and 2D or 3D density distribution of at least one component of multiphase systems and dynamic features of the phase of interest, such as flow pattern, velocity field, and 2D or 3D instantaneous movements. This chapter summarizes the progress and developments in flow imaging techniques in microreactors and microchannels using a range of tomography techniques: γ-ray, X-ray transmission tomography, X-ray radiography, neutron transmission tomography and radiography, positron emission tomography, and electrical impedance tomography. The basic principles of the techniques are outlined, along with advantages and limitations inherent to each technique.

A computational study of effects of vessel dynamics and compliance on coronary artery hemodynamics with/without stenosis is presented. The coronary artery hemodynamics with stenosis has been a main subject as one of the major cardiovascular diseases induced by atherosclerosis most computational models assume that the vessel movement and deformation are negligible (Zeng, et al., 2003 Kim, et al., 2010). However, it is still unclear whether the hemodynamic characteristics owning to vessel dynamics and compliance are clinically significant or not particularly under pathological conditions. In this study, we aim at investigating the hemodynamic effects of the vessel dynamics and compliance in right coronary artery under healthy situation without stenosis as well as under diseased conditions with stenosis. We constructed a three-dimensional geometric model of the right coronary artery based on X-ray angiographic images, in which both vessel movement and deformation were taken into account. A specific volumetric flow rate was employed as a boundary condition imposed on inlet. Furthermore, we carried out an extensive study on the inlet waveform dependence and the effects of the vessel compliance on coronary hemodynamics. Our results demonstrate that the conventional assumption on 'rigid' artery models holds only in the cases of normal coronary arteries but fails for stenosed coronary arteries where the vessel dynamics and compliance do extend significant influence on distributions of the oscillatory shear indices (OSIs). Moreover, we find that the effects of vessel dynamics and compliance on coronary hemodynamics seem to be independent of both inlet boundary conditions and the vessel compliance.

In microfluidic applications, in order to produce the high yield of desired product, the study of particle migration is very important to enhancement and increases the efficiency of positioning and sorting process. One of an effective and robust method for visualization imaging, passively positioning and sorting microparticles and cells without the assistance of sheath fluid is electrical capacitance. In this study, to study the behavior of particle migration, a fine particle concentration in a cross-sectional microchannel is determined for the high dense initial particle concentrations (ξ=10.0%) and small particle diameters (dp= 2.1 μm) by using a high speed multiplexer and 12 multi-layer electrical capacitance tomography (ECT) sensing to discuss the stream migration along five cross-sections. The polystyrene particles as solid phase and non-conductive deionized water as a liquid phase are non-uniformly injected into the inlets microchannel. From the electrical capacitance distribution, the tomography images that show the equilibrium particle migration is reconstructed by used the Tikhonov regularization method. It has been observed that the particle concentration at the wall vicinity area is increased as ξ and dp are increased while the particle concentration at the center area is decreased. It shows the particles are moved away from the center towards wall vicinity area and particles migrated towards the wall increased in the outlet area as the particles move along the cross-sectional microchannel. The experimental result is verified with the COMSOL simulation.

Various extracorporeal circulation devices require a real time thrombus detection system. This paper presents a study toward the establishment of real-time thrombus detection by measuring the electrical properties of blood. We conducted experiments on static bovine blood samples and determined the change in relative permittivity of the samples by changing the size and red blood cell (RBC) concentration of the thrombus in each sample. Results show that the relative permittivity increases linearly with increases in the number of RBCs that form the thrombus. Similarly, permittivity also increases linearly with increases in the volume of the blood that forms the thrombus. These results are consistent with the numerical simulations. However, we found the linear relationship to be dependent on the AC frequency of the applied voltage. We compare and explain this dependency on the basis of earlier studies.

This report presents a study of the dynamics dispersion behaviors of inertial particle in solid-air two-phase flow within accelerated domains using both experimental and simulation approaches. In the simulation, a three-dimensional model was proposed by means of the combined computational fluid dynamics and a discrete element method (CFD-DEM). The simulation model provides information regarding the particle distribution behaviors and the particle run-away rate from the calculation domain. In the experiment, particle image velocimetry (PIV) and laser tomography were used to measure the particle velocity and concentration distribution, respectively. The simulation results were than validated by the experimental measurement. And the influence mechanisms of acceleration on the particle flow behavior were discussed in detail. As results, acceleration of the calculation domain affects the particle motion and causes a relative dense particles distribution in the accelerated direction. The particle run-out rate under acceleration was initially the same, but subsequently lower than that of the condition without acceleration. This finding shows that the acceleration adversely affects the particle run-out rate.

In order to enhance the heat recovery properties of the circulating fluidized bed (CFB) which is proposed to be a potential choice for the waste heat recovery system in a ship to solve the corrosion problem, effect of the rolling motion induced by the ship on the bed-to-wall heat transfer characteristics has been investigated. Improved cluster-based models (ICBM), in which the potential dynamic feature change of clusters induced by the rolling motion is considered, have been proposed for the prediction of the heat transfer coefficient in the rolling CFB. The predicted heat transfer coefficients by ICBM were compared with the predicted results of cluster renewal model (CRM) which is applied commonly to the CFB at upright attitude, and evaluated by the measurement results in the heat transfer experiment. As results, the predicted heat transfer coefficient by CRM agrees well with the experimental results in the CFB at upright attitude. However, in the case that the rolling motion is applied, the heat transfer coefficient is extremely under-estimated by CRM. Meanwhile, the predicted heat transfer coefficient by ICBM I, which takes into account the disappearance of the gas layer next to the wall and the increase of the particle volume fraction in clusters due to the rolling motion, is in good accord with the measured heat transfer coefficient in the heat transfer experiments. The dynamic feature changes of the cluster are proposed to be the primary factors for the heat transfer augmentation in the rolling CFB. (C) 2014 Elsevier B.V. All rights reserved.

The ventricular assistance devices (VAD) have been very useful to the patients with chronic heart failures. But, regular consumption of anticoagulants to suppress the thrombosis results into many bleeding related complications. Such complications are also observed in the patients getting hemodialysis and patients undergoing heart surgery using heart-lung machine. Currently, the anticoagulation management is based on offline tests. But, the real-time non-invasive blood monitoring system is highly desirable to optimize the anticoagulation therapy. As a basic study in that direction, we employed electrical impedance spectroscopy (EIS) method to study the electrical chacteristics of bovine blood under thrombogenic condition. The resistance and reactance were measured in the frequency range of 1 kHZ to 5MHz. The measured values were then analyzed using equivalent circuit fitting. It was observed that the capacitance of the blood can be used to quantitatively measure the degree of aggregation of red blood cells in the blood undergoing thrombosis.

Dynamic properties of particle distribution behaviors in the circulating fluidized bed with rolling motion have been clarified by both Electrical Capacitance Tomography (ECT) experiment and CFD-DEM simulation. In the present study, the amplitude and period of the rolling motion were maintained at Theta = +/-pi/12 rad (+/- 15 degrees) and T = 5 s, respectively. Limestone particles (Geldart group B) were used as the circulating particles. As a result, the rolling motion causes little impact to the flow directional profiles of particle volume fraction due to the negligible inertial forces and changes of gravity component. However, both the experimental and simulation results indicate that the rolling motion has a dominant influence on the particle distribution un-uniformity in the radial direction. An obvious periodical variation of the particle volume fraction appears under the rolling motion due to the significant effect of the resultant force of the gravity component and inertial forces in radial direction, whereas this phenomenon did not appear under the upright condition in any previous studies. (C) 2014 Elsevier B.V. All rights reserved.

Currently, patients who undergo extracorporeal blood circulation require regular antithrombotic drugs which cause side-effects. In order to minimize the side-effect, the thrombus needs to be detected in its early stage. In this study, we have investigated the effects of calcium ion on thrombus formation by measuring time variation of the relative resistivity. The visualization of thrombus formation after adding an aqueous solution of calcium chloride (CaCl&lt inf&gt 2&lt /inf&gt ) of different concentrations to the blood has been accomplished using electrical resistivity tomography technique. The thrombosis started earlier with relatively large thrombus at the end for increased concentration of calcium ions.

The concept to extract dominant particle density fluctuation in various time-space frequency levels on a pipeline cross section has been launched using a capacitance-computed tomography and threedimensional discrete wavelets transform. With this concept, particle density fluctuation at the downstream of a pipe bend is decomposed to time-space levels in a non-choking state and a pseudo choking state. As a result, this concept enables the time and position when and where particle density fluctuations with dominant time-space levels pass through the pipeline to be determined.

Actin, a cytoskeletal protein, gathers and polymerizes under the cell membrane to mediate protrusion of the cell membrane. Therefore, actin participates greatly in cell movement. To quantitatively evaluate actin's dynamics during cell protrusion, movements of actin-labeled cells were observed under a confocal laser scanning microscopy, and time-lapse images were obtained. Image analysis of the orientation of actin stress fibers revealed dynamic formation of a meshwork of stress fibers in the protrusion structure at the leading edge of the motile cell. In addition, a number of immobile spots such as focal adhesions were observed adjacent to the dynamic meshwork of stress fibers. The distribution and the time between appearance and disappearance of each spot were analyzed. The results suggest that immobile spots close to the centroid of the cell play a crucial role in providing anchorage and driving cell movement. © 2014 The Institute of Electrical Engineers of Japan.

This study has launched a concept to measure real time two-dimensional temperature distribution non-invasively by a combination of electrical capacitance tomography (ECT) technique and Debye equation. The concept has two steps which are the relative permittivity calculation from the measured capacitance among the many electrodes by ECT technique, and the temperature distribution calculation from the relative permittivity distribution by Debye equation. ECT sensor with 8 or 12-electrode is designed to measure and visualize the cross sectional temperature distribution in heating water as a basic experiment and melting polycarbonate pellets as a main experiment. Consequently, it is found that the water capacitance is changed by 1.14x10(-6)F as every 1.0 degree Celsius water temperature change. Moreover, the images of the temperature distribution from the relative permittivity distribution are reconstructed at every time step during the polycarbonate melting process. The non-invasive temperature values by a combination of ECT technique and Debye equation were compared with the invasive temperature values by the thermocouples. The non-invasive values have a good agreement with the invasive values by approximate 5%.

A fixed bed reactor that operates in gas-liquid co-current down flow is called Trickle Bed Reactor (TBR). It is widely used in chemical engineering. And, recently used in purification of radioactive contamination from contaminated water generated in the Fukushima Daiichi nuclear power plant. There are several flow conditions that occur in the TBR due to gas and liquid flow rate. Since mass and heat transfer rate and particles wetting depend on flow condition, it is necessary to establish the visualization techniques to understand flow condition, transition boundary and properties of gas liquid flow in TBR. In this study, authors employed the lab-scale TBR, made of 100mm inner diameter acrylic column, packed with particles of two sizes (3, 5 mm) that are used in the actual reactor. Water and air were injected from the top of the column and cross-sectional liquid distribution was captured at the bottom of the column by electrical resistance tomography (ERT). ERT is a tomographic technique that provides the cross-sectional conductivity distribution at the rate of about 50 frames per second by injecting current and measuring voltages between the 16 electrodes that are attached around the column. By analyzing the spatial and temporal characteristics of the liquid distribution obtained by ERT, it was found that particle size has only little impact on induction of pulsating flow and larger particle causes distinct pulses. Smaller particle causes blurred tiny pulses due to higher flow resistance. Larger particle (5 mm) is advantageous for pulsating flow.

The mud-pulse logging instrument is an advanced measurement-while-drilling (MWD) tool and widely used by the industry in the world. In order to improve the signal transmission rate, ensure the accurate transmission of information and address the issue of the weak signal on the ground of oil and gas wells, the signal generator should send out the strong mud-pulse signals with the maximum amplitude. With the rotary valve pulse generator as the study object, the three-dimensional Reynolds NS equations and standard k-epsilon turbulent model were used as a mathematical model. The speed and pressure coupling calculation was done by simple algorithms to get the amplitudes of different rates of flow and axial clearances. Tests were done to verify the characteristics of the pressure signals. The pressure signal was captured by the standpiece pressure monitoring system. The study showed that the axial clearances grew bigger as the pressure wave amplitude value decreased and caused the weakening of the pulse signal. As the rate of flow got larger, the pressure wave amplitude would increase and the signal would be enhanced.

As part of the study to develop compact and efficient marine exhaust gas treatment system with circulating fluidized bed (CFB), effects of the swing motion of a ship on gas-solid flow in the CFB was investigated. The heat transfer efficiency of the CFB is closely related with the particle flow near the wall of riser. As a trial to evaluate the particle flow near the wall of riser quantitatively, descending velocity of particles at upright and swing condition was measured by a particle image velocimetry (Ply) system. Particle motion near the wall of riser was recorded through an observation window by a high speed camera. The recorded images were processed to evaluate the local descending velocity of particles under different swing amplitude and period. As results, the swing motion affects the down-flow of particles, namely, descending particle flow along the wall of riser. The time-averaged descending velocity near the wall of riser is remarkably decreased by the motion. Effect of the swing period on the particle descending velocity is really small. But as the swing amplitude increases, the descending velocity of particle decreased significantly.

A measurement technique that can measure the concentration of the solid particles in liquid flow was developed. The measurement system consists of a color camera and three LCD displays. The solid particles were put at the bottom of a cylindrical mixing tank in which JetA1 oil was filled. Transient mixing of the solid particles was performed by rotating a propeller type agitator, with three different rotation speed (500, 600, 700 r/min). Mixing state was visualized by the LCD displays and a color camcorder. The color intensity of the glass particles changes with their concentration. The color information was decoded into three principle colors R, G and B so that, the calibration curve of color-to-concentration was performed using these information. A neural network was used for this calibration. The transient concentration field of the solid particles was quantitatively visualized.

Initial concentration condition effect of particle cross-sectional concentrations of particle suspension two phase flows in a microchannel have been investigated. The cross-sectional capacitances between 12 sensor electrodes have been measured by a high speed multiplexer and multi-layer capacitance measurement technique in order to determine the particle concentration. The polystyrene particles as a solid phase and non-conductive deionized water as a liquid phase are non-uniformly injected into inlets microchannel. The normalized particle concentration was calculated based on the multi-layer capacitance measurement from modified Maxwell equation. The particles are migrated from the upstream to downstream cross-section, particles move away from center streamlines to near the wall vicinity area and the number of the particles migration towards wall vicinity area are clearly increased near to the outlet area. The stream transitional particle migration due to lift forces is investigated with the effect of the initial particle concentration. The results shows the particle migration ratio decreased with the increment of the initial particle concentration where in case of initial particle concentration, ξ=3.0% it shows the higher particle migration ratio from the upstream to downstream cross-section than the initial particle concentration, ξ=5.0 or 10.0%.