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We simultaneously measured the diffuse reflectance spectra and transmittance spectra of in vitro rat cerebral cortical tissue slices perfused with artificial cerebrospinal fluid (aCSF) in the wavelength range from 500 to 900 nm. An ischemia-like condition in the cortical tissue was induced by oxygen/glucose deprivation (OGD) of the aCSF. Diffuse reflectance and transmittance of the cortical slices were decreased and increased, respectively, during OGD. Spectral data of reduced scattering coefficients and absorption coefficients were estimated by the inverse Monte Carlo simulation for light transport in tissue. As with OGD, significant decrease of the reduced scattering coefficients and alteration of the absorption coefficient spectrum were observed over the measured wavelength range. The mean maximum amplitudes of change in the absorption coefficient at 520, 550, 605, and 830 nm were 0.33 [+ or -] 0.14, 0.30 [+ or -] 0.12, 0.30 [+ or -] 0.14, and -0.04 [+ or -] 0.16, respectively, whereas those in the reduced scattering coefficient at 520, 550, 605, and 830 nm were -0.37 [+ or -] 0.08, -0.38 [+ or -] 0.08, -0.38 [+ or -] 0.08, and -0.39 [+ or -] 0.08. Variations in the reduced scattering coefficients implied cell deformation mainly due to cell swelling, whereas those in the absorption spectra indicated reductions in heine [aa.sub.3] and CuA in cytochrome c oxidase and cytochrome c. [c] 2010 Optical Society of America OCIS codes: 170.0170, 170.3660, 170.6510, 170.6935.

Numerical and experimental analyses are conducted on a nanosecond pulse dielectric barrier discharge-induced nonthermal plasma (NTP) for pollution control. In the numerical analysis, a commercial simulation software, CFD-ACE+ solver, is used. The result indicates that a streamer progressing from the positive electrode to the grounded one is well simulated. At the end of the pulse, the electron temperature and electron number density in the coaxial-type plasma reactor finally reach approximately 1.7 eV and [10.sup.15] [m.sup.-3], respectively. The radial electric field is almost constant in the plasma region. During the single pulse, the peak concentration of ozone is approximately 40 ppm near the surface of the glass barrier. Next, an experimental analysis on the optical emission spectra of the NTP is carried out. In the result, the second positive bands spectra of [N.sup.2] are observed. The evaluated electron temperature is almost constant (approximately 1.8 eV), irrespective of frequency, discharge power, and radial position. This value and tendency agree well with the numerical results. Index Terms--Dielectric barrier discharge, electron temperature, emission spectroscopy, nonthermal plasma (NTP), numerical analysis, pollution control, pulse corona discharge, streamer.

Over the years, we have investigated particulate matter (PM) and N[O.sub.x] reduction using nonthermal plasma-chemical hybrid processes without using catalysts. Among nonthermal plasma hybrid processes, the ozonizer combined with the chemical hybrid reactor was investigated using a 479 cc (5.5 kW) power generation diesel engine. The PM deposited on the diesel particulate filter can be incinerated by ozone and N[O.sub.2] in a wide range of flue gas temperature. The NO was oxidized to form N[O.sub.2] by ozone, and N[O.sub.2] was reduced by the 3% [Na.sub.2]S[O.sub.3] chemical reactor. As the results, PM deposited on both metal and ceramic filters were successfully removed even at ambient temperature. The rate of PM incineration depends on the amount of ozone injected and was significantly higher than the rate of PM generation. Using 2.4% ozone concentration with a flow rate of 10 L/min, 82% of NO having 720 L/min was oxidized to N[O.sub.2], and 78% of N[O.sub.x] was removed as a chemical scrubber. However, N[O.sub.x] removal was deteriorated about 10% after 1-h operation. This was attributed to [Na.sub.2]S[O.sub.3] oxidation by air, which was evidenced by the reduction of pH in the chemical reactor. Index Terms--Diesel particulate filter (DPF), N[O.sub.x], nonthermal plasma, particulate matter (PM), plasma-chemical hybrid processes.

In this paper, the results of two experiments are reported. First, the performances of various types of nonthermal plasma reactors for N[O.sub.x] reduction were compared. It was shown that the surface-discharge reactors have as high N[O.sub.x] reduction capabilities as pulse-powered wire-cylinder reactors. Second, N[O.sub.x] treatment using the surface-discharge reactor with a NO-adsorbent zeolite 13X was performed. Thermal desorption was employed for the regeneration of the zeolite. The N[O.sub.x] of 350 ppm was kept lower than 18 ppm for at least 11 h, whereas it degraded to 75 ppm in the absence of the regeneration. The result suggested the possibility of an aftertreatment system that employed thermal desorption by utilizing the waste heat of diesel engine exhaust and N[O.sub.x] reduction by using a surface-discharge reactor. Index Terms--Nonthermal plasma (NTP), N[O.sub.x], packed-bed, surface discharge, thermal desorption, zeolite, 13X.

An effective NOx-reduction aftertreatment system for a marine diesel engine that employs combined nonthermal plasma (NTP) and adsorption is investigated. The system can also treat particulate matter (PM) that employs a diesel particulate filter (DPF) and its regeneration by NTP-induced ozone. The effect of the combined reduction of accumulated PM and NOx is studied. The marine diesel engine of interest provides an output power of 1 MW at 100% of the engine load. The NOx reduction is composed of repeated adsorption and desorption flow processes using NTP combined with NOx adsorbents. With a view toward practical use, experiments on a higher number of cycles are carried out. The amount of adsorbents is 105 kg, which is greater than that in the authors’ previous study. As a result, NOx reduction efficiency by NTP is higher than in the previous study and is greater at higher amounts of adsorbents owing to higher NOx desorption. Furthermore, DPF regeneration with plasma-induced O3 injection is achieved simultaneously. This aftertreatment system demonstrates an excellent energy efficiency of 114 g(NO2)/kWh. The present aftertreatment can generate a synergistic effect of PM and NOx reduction. [ABSTRACT FROM AUTHOR]

Atmospheric-pressure nonequilibrium nonthermal plasma hybrid exhaust gas aftertreatment systems that do not utilize precious metal catalysts, harmful ammonia, etc., have been developed by the authors. Two types of new environmental protection systems (a dry system and a wet system), which enable the production of ultralow \CO2, particulate matter and \NOx emissions as well as reduced fuel consumption and low cost, are investigated for diesel engines, marine engines, and combustion boiler applications. This paper reports the principles of the dry system and some recent experimental results of laboratory tests. The \NOx reduction comprises three flow processes: 1) adsorption, 2) heating, and 3) cooling processes. The heating process corresponds to the regeneration process. These processes are repeated in the following order: 1), 2), and 3). This dry system demonstrates excellent energy efficiencies that meet the most recent Japanese national regulations regarding automobile diesel engine exhaust gas. In this study, approximately 60% of the \NOx of the exhaust (\NOx: 240 \sim 325 ppm, \flow rate = 300\ \NL/min, N: standard state) can be treated for 35 h. An improved system energy efficiency of 143 \g\ (\NO2)/\kWh, which is the highest yet, is achieved for \NOx reduction. [ABSTRACT FROM AUTHOR]

The aim of this paper is to analyze the influence of plasma discharge reactor unit geometries on the efficiency of dry \NOx reduction process in nitrogen plasma environments. The experimental setup consists of the versatile plasma discharge reactor unit powered by 10-kHz pulse HV supply and supplied by mass flow controllers with a simulated (\NO + \N2) gas under different concentrations and flowing rates. The measurements are obtained by means of a gas analyzer for \NO/NOx concentration and a digital oscilloscope supplied with HV and current probes for discharge power computation. The number of surface discharge electrodes, the distance between them, their active area, the gas flow rate, and concentration are studied while aiming at 30 \g(\NO2)/\kWh energy efficiency and higher reduction efficiencies. These targets are the keys to industrial application of plasma discharge reactor, as a way of reducing \NOx from the regeneration phase in the next generation diesel exhaust aftertreatment system, and the results proved successful. [ABSTRACT FROM PUBLISHER]

A simultaneous reduction of particulate matter (PM) and \NOx emitted from diesel engines has been realized by means of a barrier-type packed-bed nonthermal plasma (NTP) application driven by a pulse high-voltage power supply under oxygen-lean conditions. \BaTiO3 particles having a large dielectric constant ( \sim10 000) are used as packed pellets, and carbon PM is loaded among the pellets. \NOx is reduced by N radicals, and PM is incinerated by oxygen radicals induced either by \NO \rm x or by ozone (\O3) reduction under elevated local temperatures among the pellets. From the photographs of the pellets, it can be confirmed that the carbon PM or soot is removed under the condition of lean oxygen, resulting in the simultaneous removal of the PM and \NOx. An optimal value for the mass of the loaded PM exists, and when the loaded PM mass is greater than a threshold value, the effect of the NTP induced by the partial discharge is too weak to simultaneously reduce the PM and \NOx. Under the optimized plasma condition, the experiment yields energy efficiencies of 2.2 g/kWh for the PM incineration and 4.3 \g(\NO2)/\kWh for the \NOx reduction in the experiment. [ABSTRACT FROM AUTHOR]

In this paper, the results of two experiments are reported. First, the performances of various types of nonthermal plasma reactors for NOx reduction were compared. It was shown that the surface-discharge reactors have as high NO,. reduction capabilities as pulse-powered wire-cylinder reactors. Second, NOx,. treatment using the surface-discharge reactor with a NO-adsorbent zeolite 13X was performed. Thermal desorption was employed for the regeneration of the zeolite. The NOx. of 350 ppm was kept lower than 18 ppm for at least 11 h, whereas it degraded to 75 ppm in the absence of the regeneration. The result suggested the possibility of an after treatment system that employed thermal desorption by utilizing the waste heat of diesel engine exhaust and NO,. reduction by using a surface-discharge reactor. [ABSTRACT FROM AUTHOR]

An efficient NOx reduction aftertreatment technology for a marine diesel engine that combines nonthermal plasma (NTP) and NOx adsorption/desorption is investigated. The aftertreatment technology can also treat particulate matter using a diesel particulate filter and regenerate it via NTP-induced ozone. In this study, the NOx reduction energy efficiency is investigated. The investigated marine diesel engine generates 1 MW of output power at 100% engine load. NOx reduction is performed by repeating adsorption/desorption processes with NOx adsorbents and NOx reduction using NTP. Considering practical use, experiments are performed for a larger number of cycles compared with our previous study; the amount of adsorbent used is 80 kg. The relationship between the mass of desorbed NOx and the energy efficiency of NOx reduction via NTP is established. This aftertreatment has a high reduction efficiency of 71% via NTP and a high energy efficiency of 115 g(NO2)/kWh for a discharge power of 12.0 kW. [ABSTRACT FROM AUTHOR]

In order to estimate multispectral images of the absorption and scattering properties in the cerebral cortex of in vivo rat brain, we investigated spectral reflectance images estimated by the Wiener estimation method using a digital RGB camera. A Monte Carlo simulation-based multiple regression analysis for the corresponding spectral absorbance images at nine wavelengths (500, 520, 540, 560, 570, 580, 600, 730, and 760 nm) was then used to specify the absorption and scattering parameters of brain tissue. In this analysis, the concentrations of oxygenated hemoglobin and that of deoxygenated hemoglobin were estimated as the absorption parameters, whereas the coefficient a and the exponent b of the reduced scattering coefficient spectrum approximated by a power law function were estimated as the scattering parameters. The spectra of absorption and reduced scattering coefficients were reconstructed from the absorption and scattering parameters, and the spectral images of absorption and reduced scattering coefficients were then estimated. In order to confirm the feasibility of this method, we performed in vivo experiments on exposed rat brain. The estimated images of the absorption coefficients were dominated by the spectral characteristics of hemoglobin. The estimated spectral images of the reduced scattering coefficients had a broad scattering spectrum, exhibiting a larger magnitude at shorter wavelengths, corresponding to the typical spectrum of brain tissue published in the literature. The changes in the estimated absorption and scattering parameters during normoxia, hyperoxia, and anoxia indicate the potential applicability of the method by which to evaluate the pathophysiological conditions of in vivo brain due to the loss of tissue viability.

Diffuse reflectance spectroscopy using a fiber optic probe is a promising technique for evaluating the optical properties of biological tissue. We herein present a method for determining the reduced scattering coefficient, μ's, the absorption coefficient, μa, and the tissue oxygen saturation, StO2, of in vivo brain tissue using a single-reflectance fiber probe with two source-collector geometries. We performed in vivo recordings of diffuse reflectance spectra and of the electrophysiological signals for exposed rat brain during the cortical spreading depression evoked by the topical application of KCl. The time courses of μa at 500, 570, and 584 nm indicated the hemodynamic change in the cerebral cortex as well as StO2. At 570 nm, the time course of μ's was well correlated with that of μa, which also reflects the scattering by RBCs. On the other hand, increases in μ's at 500 and 584 nm and a decrease in μ's at 800 nm were observed before the profound increase in μa, and these occurrences were synchronized with the negative dc shift of the local field potential. The resultant change in the slope of μ's ðλÞ is indicative of the morphological changes in the cellular and subcellular structures induced by the depolarization due to the temporal depression of the neuronal bioelectrical activity. The results of the present study indicate the potential application of the proposed method in evaluating the pathophysiological conditions of in vivo brain., (© The Authors.)