The effects of pressure on the outwardly propagating turbulent flames were studied for propane-air mixtures at the equivalence ratios from 0.8 to 1.3 and the initial pressure from 0.10 to 0.50MPa. The turbulence intensity of the mixture was set to 0.80 and 1.59m/s. The ratio of turbulent burning velocity to unstretched laminar burning velocity increased with the increase in the initial mixture pressure at all the equivalence ratios. It seemed to increase as the Markstein number decreased. Laminar flames with the small Markstein number were unstable. Turbulent flame seemed to be affected by the flame instabilities.

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Burning velocities of methane/air mixture at pressure ranging from atmospheric pressure to high pressure up to 1.0 MPa and mixture temperatures of 300 K and 573 K were measured for Bunsen-type flame stabilized in a high pressure chamber using OH-PILF. Based on the contours of the mean progress variable, <c>, turbulent burning velocity was determined. Bending tendency of S_T/S_L curves with u'/S_L was also seen at high pressure and temperature. The turbulence Reynolds number region where the bending occurs corresponded well to the region where the smallest scale of flame wrinkling measured as a fractal inner cutoff approaches the characteristic flame instability scale. Flame instability for the flow without turbulence was also measured and the increase in nominal burning velocity was confirmed at high pressure and high temperature.

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The influence of the addition of hydrogen to methane mixtures on its local burning velocity is investigated directly. Hydrogen added lean and rich methane mixtures having nearly the same laminar burning velocity with different rates of addition of hydrogen are prepared. A two-dimensional sequential laser tomography technique is used to obtain the temporal statistical relationship between the flame shape and the flame displacement The local flame displacement velocity Sp_F is quantitatively obtained as the key parameters of the turbulent combustioa The obtained S_F is also discussed by the concept of Markstein number.

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In this study, we have investigated the local flame structure using OH-PLIF system. We have used a cyclone-jet combustor to establish turbulent premixed flames for propane/air mixtures, covering the flamelet regime and thin reaction zone regime on the combustion diagram. By comparing the experimental results with calculations using GRI-Mech 3.0, the OH concentration is quantitatively determined. When the velocity is increased, flame motion is larger to have large fluctuation in OH profile. The peak OH concentration in flame zone is smaller. This fact can be interpreted as the decrease of the local burning velocity due to the incomplete reaction by large strain rate.

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This paper explores that simultaneous OH/acetone PLIF can be applied to visualize "flame zone" of premixed flame. OH and acetone can be excited by a Nd:YAG pumped dye laser with a frequency doubled 283.222nm tuned to the Q_1 (7) OH line fluorescence signal, and appropriate band pass filter mounted to ICCD system is selected to collect these fluorescences. OH and acetone act as tracers of burned region and unburned region, respectively. The results indicate that only OH and acetone are excited with the laser, and the flame zone could be seen as dark separated zone between the distribution of OH and acetone in PLIF images.

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Simultaneous measurements of CH and OH radicals by planar laser induced fluorescence and three-component velocity by particle image velocimetry are conducted in turbulent premixed flames with different Reynolds number and equivalence ratio. In turbulent flames, which is classified near the boundary between corrugated flamelets and thin reaction zones in the turbulent combustion diagram, the minimum curvature radius of the flame front coincides with Kolmogorov micro scale and independent of Reynolds number and equivalence ratio, whereas probability of flame element with small curvature radius decreases with the decrease of equivalence ratio. Strain rate tangential to the flame front is of the order of the inverse of Taylor time scale.

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We carried out the flow field measurement of methane-oxygen turbulent nonpremixed flame in noncombusting and combusting situations under high pressure using LDV. Direct observation and CH^* chemiluminescence measurement are conducted in high pressure up to 1.0MPa. It was found that the flame length at elevated pressure became constant. From flow field measurements, the following features of the flame at elevated pressure were found : (1) the existence of the flame suppresses turbulence in the upstream region of the jet flow and enhances it in the downstream region with increasing pressure ; (2) Turbulence in the flame is more anisotropic than in the corresponding cold jet in all regions of the flow with increasing pressure ; (3) Reynolds shear stress was not changed at elevated pressure ; (4) The combustion process has been found to have a marked influence on the turbulence integral scale under high pressure, however, even increasing pressure, turbulence integral scale was not changed.

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The effects of turbulence characteristics on local flame structure and the fractal feature of flame front are investigated by direct numerical simulations of hydrogen-air turbulent premixed flames propagating in three-dimensional homogeneous isotropic turbulence. The maximum heat release rate in high Reynolds number turbulence reaches to 1.4 times of that in the laminar flame, whereas fractal dimension of the flame surface are 2.3〜2.5 and independent on Reynolds number. The finite flame thickness causes the difference in the growth rate of flame surface area and turbulent burning velocity. This difference is collapsed by the ratio of the diameter of coherent fine scale eddy to the laminar flame thickness (D/δ_L). The inner cutoff scale, which is about 10 times Kolmogorov micro scale, also shows good correlation with D/δ_L

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We have modeled the combustion-related terms in the transport equation of the turbulent kinetic energy for turbulent premixed combustion. In this paper, the modeling of diffusion terms was discussed to close the κ-equation. The turbulent diffusion, pressure diffusion and viscous diffusion terms were modeled together as a gradient diffusion type model. And the diffusion model was compared with diffusion terms estimated from DNS data of turbulent premixed flames, where the model constants were applied general experimental values. Then this result predicts that the experimental model constants are acceptable for κ-equation model of the turbulent premixed combustion.

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A new turbulence model called "hybrid model" was proposed to simulate turbulent premixed combustion with flame-generated turbulence and counter-gradient diffusion. This model calculated the Reynolds stress by a modified two-equation model including pressure terms, which represented turbulence generation due to combustion. It also calculated the turbulent scalar flux by a second moment equation including pressure and reaction terms, which represented the counter-gradient diffusion. The model constants were evaluated by DNS database, and these models were in good agreement with DNS. It was proved that the simulation of one-dimensional propagating turbulent flames by this "hybrid model" could express both turbulence generation and counter-gradient diffusion.

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The author presents a new energy recycling concept that creates an energy transport medium, through the use of DME. In a conventional way, waste heat that has been generated by power plants and industry, has been recovered as sensible heat which is steam, hot water or preheated air for combustion. DME can be inverted to hydrogen, this heat value will increase the original heat value of DME, by waste heat recovery. Hydrogen energy is expected to be used in the future as an energy source which uses fuel cell that will be used by and will undeniably benefit transporters and private power plants. In addition, DME is useful in the prevention of disaster as well as advancing environmental protection measures.

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This study focuses on the fundamental characteristics of DME combustion, aiming at the development of a new low-NOx combustion technology suitable to DME. Combustion experiments using diffusion burner were conducted for characterizing DME through the comparison with the results of LPG and ISA-city gas. The NOx emission of the DME was over 130ppm, which is higher than that by the other fuels. By applying the low-NOx combustion system, referred to the tube-nested combustion, NOx emission of DME was extremely reduced from 120ppm to 20ppm at 0% O_2. Then the dimension of the burner plate was examined to optimize the DME combustion.

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Dimethyl ether (DME) attracts attention as next-generation fuel from stable supply of energy resources, and a viewpoint of an environmental problem. The manufacturing method is already being established and development of the usage is an important subject from now on. Although being used as gas turbine fuel is also assumed, for that, it is necessary to grasp the combustion characteristic of DME. Then, in this research, the turbulent diffusion combustion experiment of DME was conducted and combustion exhaust gas composition etc. were measured as well as comparison with city gas combustion.

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In this study, experimental and numerical studies were perfomed to investigate the turbulent flow field in a gas turbine combustor. In the experiment, velocity components in each direction were measured using hot-wire anemometer. In the numerical simulation, the flow fields in the combustor with and without casing were numerically analyzed using Large Eddy Simulation (LES) as a turbulence model. The existance of recirculation zone was observed in both experimental and numerical results. It was obtained from simulation that the inlet conditions for secondary and dilution air were also different in both cases, and it seems to be caused by the swirling flow in the combustor. It means the secondary and dilution air flow have momentum not only in radial direction but also in axial and tangential directions. By including casing spaces in computational domain, the momentum of secondary and dilution air was able to be predicted, and more accurate predicted results of flow field in gas turbine combustor were obtained.

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Pilot scale entrained coal gasifier used in IGCC (Integrated Coal Gasification Combined Cycle) is numerically analyzed. Flow field and particle trajectory are calculated using Euler-Lagrange approach by cold model. In this paper, the throat diameter and the number of slag holes are mainly discussed. As a result, calculated results are in good agreement with experimental ones in axial and tangential velocity components. The effect of the throat diameter affects flow field, i.e. the larger the throat diameter, the smaller the axial velocity component in the upper part of combustor. On the other hand, it is shown that the effect of the number of slag holes on flow field is small.

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Radiative heat transfer in a turbulent pulverized coal combustor is analyzed using the Discrete Ordinate Method (DOM). Various combustion gases, coal particles and soot as absorbing-emitting-scattering medium, involved in the combustor play a significant role in the thermal radiation. In this paper, the effect of particle radiative properties on temperature field is investigated. The results have shown that the soot particles have a great influence on the wall radiative heat flux and the temperature field in the furnace. However, the effects of the difference of scattering phase functions by pulverized coal particles on the temperature field are found to be insignificant.

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The thermal radiation properties are studied for a cloud of coal char and ash particles. The monochromatic absorption of the sample particles dispersed in liquid paraffin wax is measured spectroscopically at an atmospheric state by using FT-IR. The effect of the particles number density in the cloud and the thickness of the dispersion layer on the spectrum of absorption could be expressed in the property of the extinction efficiency. The spectral distribution of the extinction efficiency is dependent of wavelength in the near infrared region of 0.8 to 2.2 micrometers. The extinction efficiency is influenced significantly so as to rise with increasing the carbon content in the char, and is correlated by a 2nd order polynomial function of the content. The contribution of scattering by ash particles can be ignored, or the forward scattering dominates the particle scattering in the radiative heat transfer in the cloud.

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A bench scale pulverized coal combustor with oxygen has been designed. Experiment is conducted in a down-fired, cylindrical and vertical furnace. High combustion efficiency has been achieved, and it depends on the oxygen ratio and primary and secondary oxygen flow ratio. The conversion ratio of fuel nitrogen to NO_X is increased significantly up to 1800 ppm, as the oxygen ratio increased. From the results of flow diagnostics by using PIV, particle image velocimetry, for the cold flow model of the burner, there are strong relations between combustion efficiency and slip velocity as well as radial vorticity profiles.

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The paper discusses a feasibility study on the direct pressurization for the steady flow in a tube through the exergy regenerating combustion to yield the acceleration of swirl flow. The effective combustion method is presented, in former part, to realize the acceleration of flow rather than the temperature increase and subsequently to show the application to swirl flow acceleration which results in the high pressure recovery.

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This paper performed the transient core analysis of a small molten salt reactor in the case of blockage accident. The emphasis is that the numerical model developed in this paper takes into account the interaction between fission reaction and fuel salt flow. The model consists of two group diffusion equations for fast and thermal neutron fluxes, balance equations for six-group delayed neutron precursors and energy conservation equations for fuel salt and graphite moderator. The results of transient analysis in the case of blockade accident are as follows ; (1) neutron multiplication factor hardly changes, (2) the outlet temperature of fuel salt decreases 10 K, and (3) fuel salt and graphite temperatures largely increase at the blockage point, but lower than fuel salt boiling temperature and the molten temperature of the reactor vessel.

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This paper discusses two new concepts for miniaturized AMTEC cells. The miniaturized AMTEC cells, which have larger packed electrode area in the same volume, are expected to have a feature to increase their volumetric output power densities. The first concept is direct deposited micron-scale current leads. The Mo micron-scale current leads, directly deposited on the cathode side electrode surfaces by laser CVD method, can eliminate the necessity for the conventional tied-on metal mesh current lead structure. The second is the addition of guard pipes on beta"-alumina solid electrolytes. The use of such pipes can reduce mechanical stress of the cells. A thermal and mass transfer analysis on the configuration factors has been performed. The influence of sodium vapor pressure drops of the guard pipes was evaluated and the optimum geometrical arrangement was considered. The expected power density of the direct deposited current leads was also evaluated. Because the contact resistance can be reduced significantly, the predicted output power is 25% higher than that of the conventional mesh lead cells.

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By the development of micro-fabrication technology, much smaller-size electronic devices will be soon available. In such a smaller device, non-equilibrium state might be appeared for careers in metal and/or semiconductor which composes the device. In such a situation, the device performance estimation by the macroscopic transport equations that assume quasi-equilibrium distribution is difficult. Then we are developing a numerical code based on Boltzman transport equation (BTE), which can analyze thermal and electric phenomena even when the state is far from equilibrium. In this presentation, we show the numerical method of BTE for free electron in metal and the calculation result of thermopower and heat flow.

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Nano heater sensor is developed in order to improve fluidic devices. Our nano heater sensor has three metal thin wires. Each thin wire is of a few hundred nanometers. By means of forming a trench that is no more than a micrometer in width, heat loss from thin lines to silicon substrate is reduced. Consequently nano heating or sensing works only on the trench. The feasibility of this nano heater sensor is treated by theoretical analysis and test devices are fabricated using NEMS (Nano Electro Mechanical Systems) technology represented by electron beam lithography, lift-off patterning and isotropic and anisotropic etching.

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Numerical calculation of submicron silicon MOSFET with CMOS structure is performed. Conjugate nature of the thermal and electrical behavior in the device is considered, and the lattice temperature is solved as well as the carrier concentration and the carrier temperature. The numerical results show that the electrical interaction with neighboring devices is a little more serious than the thermal interaction. Furthermore, by comparing the results of this analysis with that of previous analysis, which are considered only one silicon MOSFET, the importance of the device analysis considering CMOS structure is discussed.

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Expansion of a single coalesced bubble rapidly growing on a small film heater succeeding spontaneous nucleation is investigated experimentally under various heating conditions using two-stage heating pulse. The maximum volume and the volume expansion rate of the bubble are shown to increase with the increase in superheated energy stored in the liquid layer before the boiling incipience and to be well correlated with the superheated energy. The shape of the bubble at the maximum volume is also shown to be well correlated with the maximum volume. The obtained results suggest that the bubble size and growth rate can be actively controlled to the prescribed values by the preheating effect at the first pulse stage.

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Recently, the systems which automatically react and analyze reagent, for example μTAS, is focused. However, Reynolds Number is so low that there is problem that it takes long time to mix fluidics. We exhibited that it is possible that we can fabricate mixing enhancement system by controlling electroosmotic flow (EOF) and temperature locally from results which cause experiment and simulation.

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Cooling performances for small heat sinks, each of which is composed of small fins and a base, investigated in condition of combined natural and forced air convection, should also be explored in designing the heat sink on a LSI package. An experimental study was performed with respect to natural air convection and forced air convection. Several kinds of small heat sink, which have different base areas, fin intervals and fin heights, are prepared. In natural air convection experiments, the effect of the supplied wattage on the temperature rise of the heat sink was examined for different fin intervals and fin heights. In forced air convection the effect of the air velocity on the temperature rise of the heat sink was examined for different fin intervals and fin heights. From these results, non-dimensional correlations for combined natural and forced air convection to design small heat sinks are presented.

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We have proposed compact thermal modeling method for high-frequency inductors that takes into consideration the effect of proximity losses and the effect of anisotropic effective thermal conductivity on the winding surface temperature. The modeling method was developed on experimental dummy inductor, and the power loss of the inductor was prescribed in advance. However, in many actual cases, the rate of heat dissipation from the high-frequency inductor is unknown or difficult to estimate precisely. From the viewpoint of practical use at the design phase, it is necessary to develop the thermal modeling method that is integrated with power loss calculation method. This paper describes the power loss calculation method for the high-frequency inductor used as a boost choke in switch mode power supplies.

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For use of oscillating heat pipes (OHPs) in a space environment, in addition to a high performance, it is very important that they work in a wide range of conditions, temperature and heat input. In this paper, the operating limit expansion of OHP by using capillary effect was studied experimentally. To prevent dry-out, a grooved OHP and an OHP in which a wire wick was partially inserted were proposed. Although the grooved OHP did not show a marked improvement on the operating limit and heat transport performance, the wire-wick OHP showed a good performance. In case of a filling ratio of 50%, the operating limit of heat input could be improved about 20% as compared with that of the without-wire-wick OHP.

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The maximum operating heat transfer rate of heatpipes with bend was investigated. In this paper evaporation part of the heatpipe was heated with uniform heat flux by flexible sheath heater, instead of cartridge heater with heater block in previous work. We measured temperature profile of several point on evaporation part wall of the heatpipe. The results show the dryout begins at the middle of evaporation part. We confirmed that the correlation representing the flooding limit by taking the influence of the heatpipe height agrees with the experimental results on bended heatpipe heated with uniform heat flux.

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Liquid cooling system for Blade Server has been developed. The liquid cooling technology brings ultra-dense and high-performance Blade Server into reality. This system provides us freedom of layout to pursue ultimate-compactness. The main components of this system are water pumps, liquid cooling jackets, a radiator, system fans, and couplings with auto-shut-off valve for high fault-tolerance. The system for Blade Server has been established experimentally, and its cooling performance was evaluated. It was found that the performance of the system depends on performance of the radiator, and the liquid cooling system was very effective in the enhancement of the cooling performance for Blade Server.

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The aqueous solution of ammonia has been used not only for refrigeration cycle but also for waste heat recovery power systems and other purposes. Thus, the thermodynamic and transport properties of NH_3-H_2O mixtures over a wide range of state parameters are needed. Authors measured the pVTx properties of this substance and found out the behavior of the maximum densities for the aqueous solution of ammonia. This paper describes the behavior and correlation of the maximum density equation of NH_3-H_2O mixtures based on the experimental data.

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Measurement of surface tension by ring or plate method is usually carried out at an atmospheric pressure to avoid the complexity of the apparatus used. We have developed an apparatus with a ring for measuring the surface tension of the liquid under pressure. The present apparatus has a load cell to detect force from the surface tension and also a device to control the distance between the ring and the surface of test liquid by making use of gravitational force. The overall uncertainty in surface tension with this apparatus is estimated to be less than ±5%. Measurements for R134a at 283 K and 288 K reveal that the deviation of present data from the reference is within ±2.5% and the data reproducibility is also within ±2.5%.

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During changing process of internal structure in a material, the variation of the thermophysical properties reflects the structural change, and at the same time, it can control heat transport in the material. Therefore, real-time information in the form of successive data on thermophysical properties is very important for material processing. We have developed the forced Rayleigh scattering method (FRSM) to apply a real-time monitoring system for the thermal diffusivity in non-invasive manner. In the present study, we have attempted to monitor the dynamic behavior of the thermal diffusivity for a thermally responsive polymer. From the results of continual measurements in the course of conformational change, it is demonstrated that the FRSM has a pretty potential for real-time monitoring system of a material even undergoing a transient process.

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Thermophysical properties of molten refractory metals have been measured using an electrostatic levitation furnace. The developed levitation furnace could stably levitate molten samples at temperatures exceeding 3,000 degrees C. In addition, non-contact thermophysical properties measurement techniques have been implemented. Properties such as the density, the surface tension, and the viscosity have been measured over wide temperature ranges, including the undercooled region.

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A ground-based electrostatic levitation equipment that can levitate a liquid drop under terrestrial condition is developed to understand the oscillatory motion up to large-amplitude. Levitation of water drops with a few millimeters in diameter has been achieved. We were able to control the oscillation mode whose number was m = 2 and the oscillatory motion up to large-amplitude, and induce drop rotation by imposing an acoustic torque. Preliminary results that demonstrate drop oscillation and amplitude dependence of frequency with rotating and non-rotating liquid drops are presented.

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Local thermal conductivity measurement method on the Scanning Thermal Microscope (SThM) has been studied experimentally. Since quantitative measurement of the conductivity requires thermal conductance and another information related to contact area, our new method uses heat flow and contact temperature between a heated cantilever and a sample. The micro thermal cantilever including heater, thermocouple, thermopile and electrode for contact thermocouple was developed. The sample was coated with gold thin film as another electrode for the contact thermocouple. The experiment in the force curve mode operation shows that the heat flow increases and the contact temperature decreases as a contact load increases, and vice versa. Although measured ratio of the conductivity between gold and glass samples were much smaller than the theoretical value, the new method detects difference in the local thermal conductivity.

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This paper treats silicon dioxide thin films for effective thermal insulator of PowerMEMS. Two SiO_2 layers with different deposition process on Si substrate are manufactured. This structure has two thermal interfaces, which block up the heat transfer into Si substrate. Thermal conductivity of this SiO_2 layer structure is measured using the 3 omega method. The interfacial thermal resistance of two SiO_2 layers are also obtained. The measurement results are discussed more effective SiO_2 thin film structure is proposed.

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We propose a diagnosis technique for microstructure of surfaces by a specular reflection technique in thermal radiation spectroscopy. An experiment is made on rough metal surfaces to verify the performance of the proposed technique.

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There is seldom the radiative prop erty of semiconductor wafers. It is important to know radiative properties of the wafer with a thin film for the accurate measurement of wafer temperature using the radiative thermometer and the estimation of the film thickness at in -situ. We measured the spectral normal emissivity of silicon wafers with various films without changing the condition of a thin film at 600℃ and 900℃. The result showed that radiation characteristics greatly differ by film kind and film thickness. It seems to be able to the estimation of the film thickness in the process by measuring the infrared spectrum at in-situ using this property.

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We have designed an apparatus for measuring thermal conductivities of thermal insulations in the temperature range from 100 to 1500℃ under atmospheric pressure and vacuum conditions by applying the cyclic heat method, and have tried to measure the thermal conductivities of alumina silica board and alumina silica blanket under vacuum condition of about 1 Pa at high temperature. The measured values under vacuum condition are shown to be smaller than those obtained by subtracting thermal conductivity of air from those of the specimen under atmospheric pressure. If the whole thermal resistance of the specimen is composed of resistances based on conductions in solid and gas, and radiation, the measured thermal conductivity under the vacuum condition would agree with the above subtracted thermal conductivity. In this study, validity of the thermal resistance model has been investigated by using electrical analog which considers various sizes of porosities in the interior of junction where the adjacent fibers are intersected.

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The freezing behavior of liposomes was investigated with differential scanning calorimetry (DSC). As a cell model, unilamellar liposomes with diameters of 20-90 μm were prepared in water, DMSO solution, and protein solution. The cooling curve from 20 down to - 50℃ for a liposome dispersion, monitored at a cooling rate of 1℃/min, showed several heat flows related to water crystallization. This behavior was different from that observed in the case for solution only. The effects of liposome size and solution composition on the degree of supercooling and the latent heat of solidification were discussed.

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To assess the viability of vitrified biological tissue by measurement of the effective thermal diffusivity (ETD), intracellular ETD was estimated. Human fibroblasts were cultured at 10^6 and 10^7 cells/cm^3 for 2 days in a collagen sponge (φ20×1 mm) to prepare artificial tissue. The artificial tissue was frozen at cooling rates of 200 to 800℃/min from 4 to -196℃ in culture medium containing with 35wt% propylene glycol. The temperature of the artificial tissue was increased stepwise from -190 to -185℃ ; the ETD was determined by using a Laplace transform method. Post-thaw viability was evaluated by using a trypan blue exclusion assay. Intracellular ETD was estimated by a Maxwell-Eucken equation. As a result, estimated ETD was higher than extracellular ETD, and decreased with increasing the cooling rate.

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Process of cell damage and death due to the hypertonic electrolyte solution was modeled as a kind of reaction kinetic process. In our previous experiment, the cells were exposed from an isotonic solution (physiological saline) to a hypertonic electrolyte solution (concentration C_m and exposure time τ) back to the isotonic solution, and the cell viability was measured. An analytical solution with reaction rate constant determined by means of the inverse problem analysis had a good agreement to the cell viability obtained in the experiment. Also, the probability distribution, probability density function of cell death, and reaction kinetic properties were investigated. The result indicates that the cell damage and death proceeds similarly as a reaction kinetic process.

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A non-invasive technique was developed to measure the thermal conductivity and thermal diffusivity of biological materials. This technique involves laser heating and infrared thermometry of the target surface. The uncertainty of estimated properties resulted from scattering of measured temperature and inaccuracy of the absorption coefficient was discussed using simulated temperature changes as measured data. Then preliminary experiments were carried out with agar gels as sham biological tissues.

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In order to make a catheter to be used in welfare and medical field, a novel whit-kinematics catheter made with shape memory alloy has been developed. This catheter responses reliably and has high accuracy in position control, Transient analysis of temperature and stress has been performed using a finite element method. At the same time, the temperature change is calculated to predict the action of the catheter and the parameters used in PID control. The numerical analysis and experimental result are compared. The performance of the catheter is accurately controlled according to the feedback of the temperature and electronic resistance.

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We propose a new method to determ ine the absorption coefficient (μ_a) of the lower layer in a two-layered medium using time-resolved spectroscopy (TRS). To estimate the variation of μ_a with the depth, the difference in the temporal profiles of light attenuation between a two-layered medium and a homogeneous one was divided into time segments, and a slope of each segment was calculated to get the time-segmented μ_a of the layered medium. Its validity was examined both by a Monte Carlo simulation and phantom experiments. The results suggest the possi bility that μ_a of hum an cerebral tissue can be selectively determined by TRS.

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The endothelial cells of microvessels form the critical barrier controlling the material exchange between the circulating blood and the body tissues. Recent experimental studies have shown that for similar size globular proteins, the microvessel permeability to positively charged proteins was much larger than that of negatively charged proteins. As a basis to investigate the mechanism of the charge effect on the microvessel permeability, we developed an electrostatic model of the transport of charged solutes through small cylindrical pores, and evaluated the permeability coefficient and the reflection coefficient, by taking into account the interaction between the surface charges of the solute and pore. It was found that even for small Debye length compared to the pore radius, the surface charge of the pore could significantly retard the transport of charged solutes with the same sign.

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Endothelial cell (EC) monolayer exposed to shear stress by a blood flow in vivo is a principal barrier for macromolecules transport across vascular wall. It is known that shear stress influences physiological and biochemical processes in ECs. Therefore we studied the effect of shear stress on transendothelial transport. Albumin transport across EC monolayer was high in a low shear stress of 1 Pa, and was low in a high shear stress of 4 Pa. Albumin uptake showed a 1.3 folds increase at 1 Pa. The albumin uptake decreased with increasing shear stress, and minimum uptake was quarter of the control value at 6 Pa.

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The internal elastic lamina (IEL) which separates the arterial intima from the media affects macromolecular transport across the medial layer. In the present study we have developed a two-dimensional numerical simulation model to resolve the influence of the IEL on convective-diffusive transport of macromolecules in the media. The model considers interstitial flow in the medial layer that has a complex entrance condition due to the presence of leaky fenestral pores in the IEL. Results for Low density lipoprotein (LDL) demonstrate a range of interesting features of molecular transport and uptake in the media that are determined by considering the balance among convection, diffusion and smooth muscle cell (SMC) surface reaction.

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