The interesterification of olive oil with palmitic acid catalyzed by Rhizopus delemar lipase was investigated in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) microemulsion systems. The maximal reaction rate was obtained at a buffer pH of 6.0-6.5. The reaction rate also attained a maximum at a W(= [H2O]/[AOT]) value of 2-5, an AOT concentration at 25 mM and a palmitic acid concentration of 125 mM. The molar fraction of the interesterified product 1,3-dipalmitoyl-3-oleoyl glycerol (POP) in the olive oil was enhanced from 2.8 to 23.1 mol% after 24 h of the reaction.

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Giant vesicle (GV), which is a compartment composed of lipid bilayer of amphipathic molecules with the diameter above 1µm, is applied as model for artificial cell membrane and expected as microreactor. GVs are generally prepared by electroformation method. However, there is no method to prepare GVs with controlled size and high entrapment yield. Microchannel (MC) emulsification is known as the method to prepare monodispersed water-in-oil (W/O) emulsions in the range from a micrometer to tens micrometers. In this study, in order to prepare GVs with high entrapment yields, we applied MC emulsification. Firstly, MC emulsification was carried out to prepare W/O emulsion using hexane as continuous phase, tris-HCl buffer as dispersed phase, and sorbitan monooleate (Span 80) as surfactant. Monodispersed W/O emulsion with the size of 4.0 µm was successfully prepared. Secondly, Span 80 was replaced with lipids mixtures consisted of phosphatidylcholine, cholesterol and stearylamine (5:5:1) as component of lipid bilayer. The substitution process was performed at -10 Celsius degree with water phase droplet frozen to avoid coalescence of emulsion droplets. With keeping water frozen, hexane was evaporated and tris-HCl buffer was added as external water phase. Using this procedure, GVs were successfully prepared with entrapment yield of 11%. The final size of the prepared GVs reflected the original emulsion droplet size.

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Emulsions are thermodynamically unstable and the emulsion droplets coalesce over a certain time depending on conditions. The coalescence of emulsion droplets is important in many industrial operations. The kinetics of emulsion coalescence determines emulsion stability and rheology, which may depend on the distribution of droplet sizes in the system. Because of the difficulty of getting monodisperse emulsion, the coalescence of droplets was only investigated macroscopically, and microscopic observation of droplets coalescence has not been studied. Recently we have developed microchannel (MC) emulsification, which is a novel technique for preparing monodisperse water-in-oil and oil-in-water emulsions. The MC plate has uniform micrometer-sized channels fabricated on a single-crystal silicon substrate using photolithographic and etching processes. Emulsions with a relative standard deviation (RSD) of approximately 10% have been successfully prepared by applying this technique. A new observation system, which monitors coalescence process in dense-packed emulsion droplets in real time, has been developed. In this study, we prepared oil-in-water emulsion with mean droplet size of 35 micrometers and RSD of 10% by MC emulsification. Coalescence processes were observed in the system and recorded through the eyepiece with a videocamera. From the images, effects of temperature and salt concentration on the coalescence rate in the flocculation of emulsion droplets were evaluated.

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Time-Temperature-Torque plot during mixing of PS and DCP revealed that the reaction was endothermic and torque reduced with increasing temperature. The activation energies increased from 50 to 90 rpm. After mixing MFI increased and intrinsic viscosity of PS dropped largely with rotor speed; i.e. from 4.7 to about 30 g/10min and 0.664 to about 0.4 dl/g corresponded to MW of 4.08 x 10^-7 to about 2.0 x 10^-7. This clearly suggests that DCP is effective to cause chain scission to PS. However, the intense of chain scission reaction with rotor speed was obvious at 150°C and insignificant at 180°C. When adding NR into the reactive PS, torque increased and mixing temperature was raised. MFI of the blend obtained at mixing temperature 150°C was lower while at 180°C was higher than that of pure styrene. Moreover, the more reduced MFI was found with higher toluene-insoluble content which consisted of both PS and NR. Insoluble part was not found in the blend produced at 180°C. This suggests that high temperature mixing is not as effective as at low processing temperature to enhance compatibility of the blend. This work reveals a possible route of making in-situ compatibilized blends which need to be developed further for better properties.

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In the removal of a good solvent from immiscible polymer blends, the solution is quenched into a particular location in the two-phase region. The resulting phase separation alters the local solvent concentration profile in the solution. However, few physical models are currently available for describing the dynamic interplay between the solvent diffusion and the polymer phase separation. Here we present experimental evidence that the diffusive resistance at the interface of separating polymers, rather than that in bulk phase, can be a source of the characteristic retardation of solvent evaporation. Two immiscible polymers of polycarbonate and polystyrene were dissolved in tetrahydrofuran at different weight fractions. The polymer solution was deposited on a substrate as a thin liquid film and then dried in the condenser drier to promote the evaporation-induced phase separation. The results indicated that the polymer phase separation significantly retards the solvent evaporation rate. At high solvent contents, the evaporation rates in ternary solutions agreed well with those in binary solutions. However, the ternary solutions exhibited lower evaporation rates than the non-separating binary systems after the beginning of phase separation. Microstructure visualization showed that an increase in polystyrene weight fraction resulted in a transition of the phase morphology from a random distribution of "disk-like" polystyrene-rich droplets to that of polycarbonate-rich droplets. The maximum decrease in evaporation rate was found to be proportional to the peripheral interfacial length between the separated domains. These facts imply that the interfacial contribution of each polymer domain is essential for describing the retarded solvent diffusion in phase-separating polymer coatings.

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Three phosphorous functional groups were introduced in one structural unit of polymer backbone to enhance the flame retardancy of PU coatings. In the first step, we synthesized tetramethylene bis(orthophosphate) (TBOP) that contained two phosphorus functional groups in one structural unit. In the next step, we synthesized modified polyesters (ATBTP-10, -20, -30) that contained triphosphorous groups by condensing polymerization of TBOP, 1,4-butanediol, trimethylolpropane, adipic acid, and phenylphosphonic acid (PPA). The amount of PPA in ATBTPs was 10, 20 and 30wt%. Then, flame-retardant PU coatings (AHFC-10, -20, -30) were prepared by curing of ATBTPs with hexamethylene diisocyanate-biuret (curing agent) at room temperature. From the TGA analysis of diphosphorus modified polyester (ATBT) and ATBTPs, the residues of ATBT, ATBTP-10, ATBTP-20 and ATBTP-30 were 24.6, 27.5, 29.2 and 31.9%, respectively. From this result, it was found that the residue increased with the amount of PPA. Physical properties of the films of flame-retardant coatings were deteriorated with the addition of PPA (flame retarding component), however, all the films of flame-retardant coatings except AHFC-30 met the required physical properties standard for coatings. Char lengths of AHFCs measured by 45° Meckel burner method were 2.9 ∼ 4.8 cm, and LOI values were 28 ∼ 31%, which indicates that the prepared AHFCs show good flame retardancy.

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Tiles are widely used for strengthening and improving the surface appearance of floors and wall in building and houses. The existing method of producing tile requires high baking temperature thus is expensive. A newly developed method of producing tiles i.e. moulding concrete mixture in flexible mould using vibrating method is an alternative production method of tile which is cheaper due to no high baking temperature is required. Nevertheless the water absorption rate is high and hence causing reduction in tiles strength. This property is improved by using thermoset Melamine-Urea-Formaldehyde (MUF) resin. The commercially available MUF resin is however are not water soluble, therefore in this research, water-soluble low formaldehyde emission MUF resin is developed and modified with other chemical so that it is compatible for unbaked tiles application. Investigation of effects of various percentage of MUF resin on unbaked tile flexure strength and water absorption rate is investigated. The research finding shows that, MUF resin produced in 3-reaction stages with mole ratio of F:U₁=9, F:M₁=2.91 & F:U₃=3.55 and 40°C End Point polymerisation has produced resin with better storage stability, high solubility in water, ability to cure at low temperature, and curing period comparable to concrete mixture setting period. Addition of 5-20% of this resin reduces the water absorption rate and maintains the flexure strength of unbaked tile. Unbaked tile flexure strength can further be improved by adding 5% of MUF resin that has been modified with 0.25% PVA added in the beginning of resin synthesis.

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In this study, the preparation of LiCl-modified mesoporous silica with active species is reported. LiCl-modified mesoporous silica was prepared by impregnating mesoporous silica with lithium chloride/ ethanol solution, followed by heat treatment at predetermined temperatures in helium. The samples were characterized using ESR and UV-vis. Hydrogen adsorption measurements were carried out under ambient condition. The heat treatment at elevated temperatures results in the increase in the amount of reversible adsorption, suggesting that the change in the state of the surface by the heat treatment is important for the hydrogen adsorption. A sharp signal was observed on ESR spectra of LiCl-modified samples after the heat treatment, indicating that an ESR-active species were produced by the heat treatment. Because both hydrogen adsorption capability and ESR-active species were generated at the same temperature range and increased simultaneously ESR-active species have very strong relation with the hydrogen adsorption sites. The electronic structure of ESR-active species was examined by UV-vis measurement. Based on these results, the surface structure and adsorption mechanism are proposed.

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Metal (Ti, Fe) containing porous materials with different surface areas have been synthesized by pillaring metal oxide between the layers of layered silicate ilerite. The BET surface areas of metal-pillared ilerite (Me-ilerite) materials were different with pillaring methods, pillaring time, and the types and amounts of metal precursors. The Me-ilerite materials of relatively large surface areas were obtained when metal precursor itself without dissolving it in octylamine was added directly to octylammonium-ilerite gel. The surface areas of Me-ilerite materials increased with pillaring time. In case of Fe pillaring, however, the surface areas decreased after some pillaring time, due to pore blocking by iron oxides formed from hydrolysis of Fe precursor in the octylammonium-ilerite gel. Also, the surface areas of Me-ilerite materials were different with the type and amount of metal precursor, due to different nature between metal precursors. Ti-ilerite materials showed higher surface areas than Fe-ilerite materials. Ti-ilerite and Fe-ilerite materials exhibited the maximum surface areas at about 15 and 20wt% of Ti and Fe precursors, respectively. The surface areas of Ti-ilerite and Fe-ilerite materials were in the range of 150-340 m²/g and 150-290 m²/g, respectively, which are much higher than that of H-ilerite used as a host, 20 m²/g. The X-ray diffraction showed that the basal spacings of Me-ilerite materials were significantly expanded by metal pillaring into the layers of ilerite. The basal spacings of Ti-ilerite and Fe-ilerite materials were in the range of 4.3-4.8 nm and 3.3-4.5 nm, respectively, which are much larger than 0.75 nm of H-ilerite. The results from the surface areas and X-ray diffraction suggested that a pillared structure with porosity should be formed between the layers of ilerite by metal oxide pillaring.

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A recent development in heat insulating materials offers a decrease in the energy consumption by air-conditioning in the summer and an improvement in the thermal performance of the insulating glass in windows and the openings of houses and buildings in the winter. A resin spacer in the insulating glass is useful for improving the insulation efficiency instead of an aluminum spacer, but water vapor is still transmitted inside the air space of the insulating glass and leads to dew condensation and decreased transparency. The lifetime of the resin spacers is predicted by the diffusion coefficient of water vapor without knowing of the dew point of the insulating glass. The amount of water adsorbed on various resin spacers made of polyisobutylene with zeolite 4A was measured at temperatures of 40-80°C, humidities of 15-95 %RH, and atmospheric pressure, for 1 h-1 month. In this study, the relationship between the lifetime of the insulating resins, the adsorbed amount of water, and the optimum component of the resin spacers for a long lifetime is discussed. The diffusion model for the transmission of water into the air space is proposed.

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Sulfonated polyimides (SPIs) were prepared from 1,4,5,8-naphthalenetetracarboxylic dianhydride, sulfonated diamines such as 4,4'-bis(4-aminophenoxy)biphenyl-3,3' -disulfonic acid and nonsulfonated diamines. Surface-resistance-type humidity sensors were prepared by coating the SPI solutions onto comb-shaped electrodes on ceramic support plates, and their sensor properties were investigated. With increasing the relative humidity RH from 20% to 90 %, the resistance R of the SPI sensors decreased by three orders in magnitude. The SPI sensors displayed excellent durability toward high temperature and high humidity and also toward water. The 90% response time was 1-2 min for humidification process and about 5 min for dehumidification. Hysteresis of R vs. RH relationship in humidification and dehumidification cycles was rather large because of slower molecular relaxation of polymer chains in the dehumidification process. The present SPI sensors have high potential of new applications based on the advantage of high water durability.

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Two types of sulfonated polyimides (SPIs) (main-chain-type and side-chain-type) were prepared from 1,4,5,8-naphthalenetetracarboxiylic dianhydride, sulfonated diamines such as 4,4'-bis(4-aminophenoxy)biphenyl-3,3'-disulfonic acid, 2,2'-bis(3-sulfopropoxy)benzidine, 3,3'-bis(3-sulfopropoxy)benzidine and nonsulfonated diamines. Membrane morphology, water vapor sorption, water stability and dimensional change, proton conductivity and methanol permeability of these SPI membranes were investigated. The resulting SPI membranes displayed high proton conductivities comparable to those of Nafion 117 at high relative humidity above 80%. They displayed excellent water durability and different dimensional change based on the membrane morphology. Most of the SPIs showed much lower methanol permeabilities than Nafion membrane and are expected to have great potential for polymer electrolyte fuel cell or direct methanol fuel cell applications

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Carbon membranes were prepared by coating thin layers of lignocresol derived from lignin by the phase-separation method and then carbonizing the lignocresol at 673?1073K by high frequency induction heating or conventional tube reactors. The thickness of the membrane formed on the outer surface of a porous alumina substrate was about 400-1000 nm judging from SEM observation. The activation energy for gas permeation through the membranes increased with increasing molecular diameter of the penetrant gas, indicating activated diffusion process. The permeation properties were dependent on heating conditions. It can be concluded that carbon membranes derived from lignin-based materials provide one of the promising candidates for high performance membrane.

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TiO₂ photocatalyst films were prepared by the low-pressure metalorganic chemical vapor deposition (LPMOCVD) at different reaction temperatures and different deposition times using TTIP (Titanium Tetra Iso-Propoxyde). First, characteristics of CVD preparation of TiO₂ films were experimentally studied as a function of CVD reaction temperature and deposition time. Secondly, photocatalitic activities of TiO₂ films were evaluated by decomposition rate of methylene blue in aqueous solution using photo-reactor. The results indicated that film thickness was linearly proportional to the deposition time. Structure of the film was strongly dependent on the reaction temperature and deposition time. Among the grown TiO₂ films, anatase and rutile showed high photocatalytic activity. However, amorphous TiO₂ films showed lower activities. The photocatalytic activity strongly depends on the film deposition time (or film thick-ness) in nonlinear way. The optimum thickness of TiO₂ catalyst film grown by LPMOCVD may locates between 3µm and 5µm.

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Effect of electrode configuration on uniformity of Cu/C:H film on polymer film was investigated. The electrodes play an important role to generate the electric field around the substrate. The applied working voltage was about (-)1.5kV. The generating electric field from the electrode makes super concentration of copper ions in the space between the electrode and substrate. In the present study, the various thicknesses of electrodes with rectangular and cylindrical shapes were employed and then their various configuration effects on the uniformity of the deposited films was investigated. For cylindrical shape electrodes, high uniform Cu/C:H film can be obtained caused by the parallel coaxial electrode configuration, which may lead the uniform electric fields around the electrode. On the other hand, in the case of rectangular shape electrode, showed non-uniform Cu/C:H film was prepared possibility due to the presence of the edge from rectangular shape. Our results showed that the surface resistance profiles of deposited film with cylindrical electrode were more uniform than that of the rectangular shape electrode. Therefore, it can be conclude that the uniformity of the deposited films was closely related to the electrode configuration such as shape, thickness, grid size and the distance between electrodes. The uniformity of film could be improved by optimizing the parameters related to the electrodes.

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The polymer particles were prepared by the precipitation polymerization in supercritical CO₂ (scCO₂). The polymer particle including the nano-size TiO₂ was successfully obtained. The effect of experimental conditions such as monomer concentration, CO₂ pressure and kinds of monomers on the particle size was investigated. The particle size decreased as the compatibility between the polymer and scCO₂ increased. In addition, the dispersion polymerization was carried out by using Krytox as a stabilizer. The addition of the stabilizer was very effective to obtain the mono-dispersed discrete particles.

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The demand for n-type diamond semiconductor with high electron conductivity at room temperature. is increasing. To synthesis high quality n-type diamond by a chemical vapor deposition (CVD), it is important to investigate the reaction of sulfur on diamond surface. In this study, the reaction of H₂S on diamond surface in microwave plasma assisted CVD process was investigated. Hydrogen-terminated synthetic diamond powder was placed into the CVD reactor, and then 500 ppm H₂S in hydrogen was introduced into the reactor and the reaction was carried out for 1 hour in the temperature range of 573-1073 K. The reacted diamond samples were analyzed by XPS and FT-IR. All sample showed a peak at S_2p region, proving the existence of sulfur. The strength of the peak depended on the reaction temperature. The result of quantitative analysis showed that the atomic ratio of reacted sulfur to carbon was largest at 673 K. A series of Diffuse Reflectance Infra-red Fourier Transform (DRIFT) spectra of the reacted samples in the temperature range of 573-973 K, showed peaks related to the sulfur compounds containing C-S bonds. This confirms that sulfur on the diamond surface is chemically bonded to the diamond surface. The shapes of spectra depended on the reaction temperature suggesting that different species are generated on the diamond surface at different temperatures. The species verified on the diamond were C-S-C and C=S. However, no evidence of C-SH group was discovered.

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In the electronics processes, downsizing of various electronic parts and increase in load of semiconductor elements cause the increase in heat production. Therefore AlN with high thermal conductivity, radiativity, and expansibility similar to Si is utilized as semiconductor packaging materials. For this purpose, highly pured AlN is required. Excellent properties of AlN remarkably fall down with increase in concentration of impurities. In recent years, AlN is manufactured by the direct nitriding and the carbothermal reduction methods. However, these methods have the problems of high reaction temperature (1500°C) and also the difficulties in continuous operations.In the present study, we synthesized AlN fine powder by direct nitriding method in a fluidized bed. The present process is expected to enable the continuous production of AlN fine powder with high conversion rate at relatively low temperature, because fluidized bed method gives excellent heat exchange; Al material are melted and distributed in the bed. To find suitable operation conditions for efficient continuous synthesis of AlN in a fluidized bed with bed materials of AlN,various operational conditions were tested. it was demonstrated that products with high purity AlN without unreacted Al were obtained at relatively low temperature (1200°C). However some parts of the product was obtained not as fine powder but as agglomerates.

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TiP₂O₇ particle was prepared by the following three methods: 1) precipitation method, 2) impregnation method, and 3) ion exchange method. TiP₂O₇ were with XRD clearly identified with XRD when the calcination temperature was 700 ∼ 900°C. The crystalline diameter of TiP₂O₇ of the samples calculated by the Sherrer's equation was found to be 10 - 65 nm. However, no peak was found in the XRD of the sample calcinated at 600°C by the impregnation method. BET specific surface area and specific pore volume of the samples were 10 ∼ 65 m² / g and 0.03 ∼ 0.31 ml/g, respectively. The BET surface area of the TiP₂O₇ prepared by the impregnation method was greater than by other two methods. These results indicate the TiP₂O₇ particle prepared by impregnation method had more porous structure.
The UV-VIS absorbance spectrum analysis of all samples was examined. All samples absorbed light in wavelength below 340nm. Especially, the two samples calcinatied at 600°C and 700°C prepared by the impregnation method, absorbed light in wavelength below 400 nm. These results suggested that non-crystalline (amorphous) TiP₂O₇ could absorb light in longer wavelength. Furthermore, we found that these two samples could photocatalytically decompose 2-propanol in water with good activity.

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The photocatalytic performance of TiO₂ thin films coated on porous alumina balls using various aqueous TiOCl₂ solutions as starting precursors, to which 1.0 mol% transition metal (Ni²⁺, Cr³⁺, Fe³⁺, Nb³⁺, and V⁵⁺) chlorides had been already added, has been investigated, together with characterizations for TiO₂ sols synthesized simultaneously in the same autoclave through hydrothermal method. The synthesized TiO₂ sols were all formed with an anatase phase, and their particle size was between several nm ∼ 30 nm showing ζ-potential of -25 ∼ -35 mV, being maintained stable for over 6 months. However, the TiO₂ sol added with Cr had a much lower value of ζ-potential and larger particle sizes. The coated TiO₂ thin films had almost the same shape and size as those of the sol. The pure TiO₂ sol showed the highest optical absorption in the ultraviolet light region, and other TiO₂ sols containing Cr³⁺, Fe³⁺ and Ni²⁺ showed higher optical absorption than pure sol in the visible light region. According to experiments for removal of a gas-phase benzene, the pure TiO₂ film showed the highest photo dissociation rate in the ultraviolet light region, but in artificial sunlight the photo dissociation rate of TiO₂ coated films containing Cr³⁺, Fe³⁺ and Ni²⁺ measured higher together with the increase of optical absorption by doping.

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Titanosilicate microporous molecular sieves, activated by UV irradiation in the presence of H₂O and molecular oxygen at room temperature, decompose a molecule having a size equivalent to the pore diameter of the catalyst, but are almost inactive for decomposition of a molecule having larger or smaller size. ESR analysis indicated that this size-selective photocatalytic activity is brought about by a combination of shortened lifetime of charge-transfer excited state of tetrahedrally coordinated titanium oxide (TiO₄) species in the presence of H₂O and restricted diffusion of the guest molecule inside the micropore of the catalyst. This observation indicates a potential utility of the titanosilicate molecular sieve as a photocatalyst for selective transformation of organic functional groups, associated with the size reduction of the molecule, so called "molecular shave" type reactions.

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Many products with relation to environmental improvement have been developed by using the photocatalytic activity of the titanium dioxide. In a heterogeneous photocatalytic system, the solid catalyst can either be suspended in liquid or be supported on substrate materials. Therefore, it had been considered that the utilization of magnetic separation could help recover fine photocatalytic particles with higher photocatalytic activity. In this work, the monodisperse pseudocubic photocatalytic particles with magnetism were prepared by gel-sol and sol-gel methods in liquid phase. These particles prepared have the core-shell structure of three layers. Core iron oxide particle sizes were controlled by reaction temperature from 0.6 to 2.2µm. The thicknesses of silica and titania layer were controlled at several nanometer by the concentration of metal alkoxides and seed particles. The photocatalytic activities were investigated by the decomposition experiments of a methylene blue under the ultraviolet irradiation. It was found that from the decomposition experiments of a methylene blue, the prepared photocatalytic particles had good photocatalytic activities and that they can be easily separated by magnetism. Furthermore, the result of the decomposition experiments revealed that the thicknesses of titanium layer mainly influenced on the photocatalytic activity

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Nanostructured oxides of CeO₂ and CeO₂/TiO₂ composite were prepared by surfactant-assisted mechanism. Metal alkoxides and laurylamine hydrochloride (LAHC) were used for synthesis of CeO₂ and CeO₂/TiO₂ composite. Highly monodispersed and crystallized CeO₂ nanoparticles of square shape were synthesized at low temperature, 353K, although formation of monodispersed cerium oxide nanoparticles was so far very difficult because of their highly aggregative properties in the aqueous reaction system. CeO₂ nanoparticles were characterized by transmission electron microscope (TEM) images, selected area electron diffraction (SAED), and X-ray diffraction (XRD). XRD and SAED results showed that CeO₂ nanoparticles had the cubic fluorite structure. Nanopaticles of CeO₂ and CeO₂/TiO₂ composite oxide showed ability to oxidize I- to I₂ without irradiation of light. This oxidation is attributed to the Lewis acid point. It was revealed that formation of Lewis acid point strongly depended on compositions of composite materials and conditions of calcination. The optimal conditions for production of Lewis acid points of the nanoparticles were found as at the mole ratio of cerium butoxide/TIPT = 75/25 and under the calcination temperature = 673K.

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Contamination of waste water and drinking water by nitrate ion is a critical issue in the world. Among various methods used (ex. biological denitration, ion exchange), catalytic reduction of nitrate has one of the highest potential. Although this method has many advantages such as simplicity of management and high rate of reduction, the selectivity to harmless product, N₂, is not high enough. Recently, we succeeded to synthesize morphologically controlled cubic Pt nanoparticles (maximum fraction of cubic particles was 70%) by reducing solution under the existence of a structure directing polymer (poly-N-isopropylacrylamide). By using this Pt nanoparticles as catalyst for NO reduction with CH₄, we found out that the reaction is structure sensitive and the morphology of Pt nanoparticles has effects on the selectivity of products. Because the mechanism of nitrite reduction may resemble to that of NO reduction by CH₄, it is highly possible that the morphology of the Pt nanoparticles can significantly affect the selectivity to reaction products. In this paper, we supported the morphologically controlled Pt nanoparticles on an alumina membrane tube having the average pore diameter of 100 nm and performed nitrite reduction by H₂ gas in a counter flow type reactor. The effect of the Pt morphology on the catalytic behavior for NO₂-/H₂ reaction in aqueous phase will be discussed in the light of experimental results.

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We have recently reported photoluminescence (PL) oscillation in both water and nonpolar-solvent dispersions of nanocrystals (NCs). In this paper, we report on the characteristics of PL oscillation in NC suspensions to clarify the mechanism. We used 5.2-nm diameter CdSe/ZnS core/shell NCs, whose surfaces were capped with tri-n-octylphosphine oxide (TOPO). PL oscillation is observed in the NC/toluene suspension as well as in a water dispersion. The period of the oscillation is revealed to be about 100 s by Fourier analysis. Since the temperature dependence on PL oscillation is similar to the scenario to chaos in closed unstirred Belousov-Zhabotinsky (BZ) system, it may be caused by a similar chemical oscillation. It is also observed that the continuous irradiation promotes the rate of NC aggregation. From these experimental results, we propose a hypothetic model which is based on both autocatalytic TOPO molecules desorption and its re-adsorption (feedback process) in the process of NC aggregation.

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Here we report that the closely packed CdSe/ZnS core/shell nanocrystal (NC) film and the isolated NC show different behaviors of the photoluminescence (PL) intensity with continuous irradiation. The PL intensity of the bilayer of closely packed NC film was enhanced by continuous irradiation of Ar laser (wavelength 488nm) under ambient air. On the other hand, fluorescence intermittency was observed by continuous irradiation for the isolated NCs. The result suggests that the photo-induced fluorescence enhancement (PFE) is attributed to the closely packed structure of NCs. It was supported the hypothesis that electrostatic potential produced by photoionization of a certain fraction of the NCs decrease the ionization probability of the adjacent NCs, and it leads to the enhancement of total emission efficiency.

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The synthesis of dimethyl carbonate (DMC) was investigated through the transesterification of propylene carbonate (PC) with methanol using quaternary ammonium salt catalysts. The reaction was carried out in an autoclave at 100-140°C under carbon dioxide pressure of 250-400 psig. The main by-product was propylene glycol. The quaternary salts of larger alkyl group and more nucleophilic counter anion exhibited higher catalytic activity. Kinetic studies are also performed to better understand the reaction mechanism.

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Porous metal oxide particles were prepared by freeze-drying to serve as combustion bulk catalysts for diesel soot. Copper oxide-based catalysts were prepared as follows: Aqueous copper sulfate solutions mixed with other metal sulfate solutions were utilized as starting materials for freeze-drying. Spherical drops of the solutions were instantly frozen in a liquid nitrogen bath. The frozen particles were dried in a vacuum chamber. And then, these were calcined into metal oxide particles, and subsequently fired to yield durable strength. The open porosity induced by sublimation of ice crystals in the freeze-dried particles was retained during calcination and firing. These porous particles would be directly utilized for the bulk catalyst packed in the diesel soot trap. The thermal analysis, TG-DTA was employed to evaluate the activity of the catalysts for the oxidation of soot from diesel exhaust and amorphous carbon powders. The mixing of carbon powder with catalysts was carried out in an agate mortar. The mixed samples were submitted to thermal analysis. The starting temperature of carbon oxidation was measured. To achieve intimate contact between catalyst and carbon powder, some metal chlorates were added to the samples expecting to form liquid phase during carbon combustion. The appearance activation energy of soot combustion was assessed for activity comparison. Among the prepared catalysts, CuO/Co₃O₄ with KCl- FeCl₂ exhibited appreciable activity and durability, showing the ignition temperature about 300°C.

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A new process for decomposing organic contaminants in water was proposed. Pulsed discharge plasma was generated in the gas phase, and the produced plasma was permeated through a pinhole into the water phase. In the gas phase, the high voltage pulse was applied between the needle electrode and the ground electrode. Water (upper) and gas (lower) were separated by an insulating plate, where a pinhole was perforated at the center of the plate. Gas was bubbled into the water phase through the pinhole. The high voltage pulsed discharge plasma was generated in the gas phase, simultaneously the plasma channel was permeated into the water phase accompanying by the gas bubbles. The water phase plasma produced a lot of active species, UV light, and high-energy electrons. Porous ceramic tube was tried to use to produce water phase plasma, instead of the pinhole reactor. It was observed that the gas phase plasma also permeated through many small pores into the water and generated plasma in water. Chicago sky blue aqueous solution was effectively decolored with oxygen gas bubbling than the cases of argon gas and air. When applying pulse voltage of 20 kV, pulse frequency of 25 Hz, with 150 mL/min oxygen bubbling, the dye aqueous solution with 10 ppm was decolored about 95 % in 20 minutes treatment. This type of plasma reactor is expected to have high-energy efficiency than other types.

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Hydrogenation of carbon dioxide was carried out in a fluidized catalyst bed. The apparent activation energy of the overall reaction rate constant obtained for the fluidized bed was almost the same as the value obtained in a fixed bed experiment. This result indicates that the role of the mass transfer between the bubble and emulsion phases was very small in this reaction system. Since we consider that the catalysts around bubbles affect the overall reaction rate in the fluidized catalyst bed, we investigated the thickness of the catalyst layer around bubbles. In addition, we reconstructed three-dimensional images of this layer by using a fast X-ray CT scanner.

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To date, many studies have successfully used anion exchange membrane in the seawater desalination, the recovery of metal ions from wastewater and the electrodialysis experiments. Because quaternary ammonium salt was verified to have a catalytic effect in a two-phase reaction systems, the purposes of this paper aim to prepare quaternary membranes and test commercial ion-exchange membrane, and conduct them as phase-transfer catalyst for the allylation of phenol in a vertical membrane reactor. The experiment results were employed to estimate the feasibility of using quaternary ammonium membrane in the phase-transfer catalytic system.
Lab-produced anion exchange membranes were prepared by polymerizing chloromethylstyrene with crosslinking reagent of divinylbenzene using the paste method. The kinetics of allylation of phenol was investigated in the organic and alkali aqueous solution. The operating conditions, such as agitation rate, reaction temperature, kind of membrane, and concentration ratio of reactants were conducted to achieve the optimum condition.

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The degradation of dyes (Acid Orange 52, Acid Blue 92, Mordant Yellow 10, Naphthol Blue Black) in aqueous solutions was investigated by using three processes (Photocatalysis, Sonolysis, and Photocatalysis with sonication (Hybrid) ). In the case of Photocatalysis, although the concentration of acid orange 52 decreased to 35% in 480 min, the color of the solution was not disappeared. In the case of Sonolysis, it was decomposed completely in 300 min, but the TOC (total organic carbon) concentration decreased to about 87% in 480 min. In the case of Photocatalysis with sonication, the concentration of it reached to 0 in 240 min and the TOC concentration decreased to about 13% in 480 min. The similar results were obtained in the cases of other dyes. These results indicate that the irradiation of ultrasonic enhanced the Photocatalysis. The addition of choride ion (50ppm) to acid orange 52 solution decreased the decomposition efficiency of Photocatalysis. In the cases of Sonolysis and Photocatalysis with sonication, the decomposition efficiency changed hardly by the addition of chloride ion. These results indicate the chloride ion disturbs the photocatalysis of dye, but the decomposition of dye using the irradiation of ultrasonic is not influenced by the chloride ion. From these results, it is considered that the Photocatalysis with sonication is most effective for the decomposition of dye among the three processes in this study.

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In this study, the oxygen transport through a solid oxide fuel cell type reactor was studied. LSM, YSZ and LaAlO were used as the cathode, the electrolyte and the anode, respectively. The oxygen permeation flux using helium as carrier gas in the anode side was 3.50x10^-7 mol m^-2 s^-1 at 1273 K with the activation energy of 170 kJ mol^-1. Changing carrier gas into methane, oxygen permeation fluxes are 1-2 orders of magnitude higher than those under helium feed. The effects of applied potentials were also investigated. The oxygen permeation fluxes were increased and the activation energies of oxygen permeation were decreased with applied potentials in both cases of helium flow and methane feed. The model of oxygen permeation was presented and the permeation parameters were proposed. In the helium case, the oxygen permeation at the LaAlO anode was the rate-limiting step for the oxygen permeation. However, in the methane case, the resistances in the three parts (LSM/YSZ/LaAlO) were comparable.

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Zirconia membranes were prepared on a porous alumina tube using sol-gel technique, and rhodium was then impregnated in the pores of the membranes by dipping in aqueous solution of RhCl₃, followed by calcination in air. The permeation rates of unmodified zirconia membrane obeyed the Knudsen diffusion mechanism. However, hydrogen permeation changed from Knudsen diffusion to surface diffusion after the Rh modification. The Rh-loaded zirconia membrane showed a H₂/CO₂ separation factor of 10 at a permeation temperature of 100°C. A mixture of H₂, CO (1%) and O₂ (0-4%) was permeated through the Rh-loaded zirconia membrane in the range of 100-250°C. When the O₂ concentration on the feed side exceeded the level of 1%, CO concentration on the permeate side was decreased to less than 50 ppm at 100°C. When the permeation temperature was raised to 200°C, the oxidation rate of CO was significantly decreased due to the consumption of O₂ by the oxidation of H₂.

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For chemical hydrides such as cyclohexane, methylcyclohexane etc., which are being considered as a promising carrier for hydrogen storage and transportation, highly efficient recovery of hydrogen from themselves should be desired. Common problems involving the processes dealing with chemical compounds are 1) that the reaction is limited by thermodynamic equilibrium and 2) that hydrogen must be separated from the gaseous mixture of the products. To solve these problems simultaneously, a palladium membrane reactor capable of upsetting the chemical equilibrium and moreover recovering hydrogen of high purity is employed. Experiment shows that more than 80% of the hydrogen recovery can be obtained at 4 bar of the reaction pressure at 300°C for cyclohexane dehydrogenation.

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A membrane reactor consisting of a reactor and a separation membrane may be suitable to provide hydrogen from hydrocarbon in order to reduce carbon dioxide. In this study, a catalytic membrane reactor, a type of membrane reactor, was designed and tested to prove if both the reactions (dehydrogenation of lower hydrocarbons, and reduction of carbon dioxide to carbon monoxide) occur on each side of the membrane in the reactor as expected. As membrane materials, LaNi₅ and CaNi₅ were chosen. In the first step, lower hydrocarbons (methane, ethane, propane and butane) were dehydrogenated at one side of the membrane; another side was swept by an inert gas. Although all the hydrocarbons were dehydrogenated, the main products were hydrogen and a coke deposited on the membrane. In the second step, simultaneous feed of propane (one side) and carbon dioxide (another side) was tried if both the reaction (dehydrogenation of propane and reduction of carbon dioxide) occurs. Carbon dioxide was reduced to carbon monoxide; propane was dehydrogenated to give hydrogen and a coke on the membrane.

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A membrane reformer is composed of a steam reformer equipped with palladium-based alloy modules in its catalyst bed, and can perform steam reforming reaction and hydrogen separation processes simultaneously, without shift converters and purification systems. It thus can be configured much more compactly and can provide higher efficiency than the conventional technologies. In the present study, we have manufactured and tested a membrane reformer with nominal hydrogen production capacity of 40 Nm³/h, with the purpose of demonstration of its capability of simple one-step reaction to produce high-purity hydrogen, its compactness, and its high energy efficiency to produce pure hydrogen from natural gas.

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In this study, we investigated the extraction of an organo-chlorine herbicide from contaminated soil and its decomposition in water by ultrasound at a frequency of 500 kHz. In particular, (4-chloro-2-methyl phenoxy) acetic acid (MCPA) was employed as an organo-chlorine herbicide sample. An aqueous suspension of model soil, prepared from kaolin contaminated with MCPA, was sonicated under an argon atmosphere in a sonoreactor. During the early period of the sonication experiment, an increase in the MCPA concentration and total organic carbon (TOC) in suspension was observed as MCPA adsorbed on kaolin was extracted out. Subsequently, this was followed by an observed reduction of MCPA, as well as TOC, in suspension as the decomposition of MCPA and its intermediates progressed. During the period of observed decrease of MCPA in suspension, the concentration of chlorine ion increased. In the same period, the sum of MCPA and chlorine ion based on the estimated chlorine present in solution was about constant. By the end of the experiment, the extraction of MCPA based on the estimated chlorine present was about 92 % of the initial MCPA adsorbed on kaolin. The remaining 8 % was presumed to be present as organic chlorine byproducts and residual MCPA adsorbed on soil. Comparison of the removal of MCPA in aqueous solution and in aqueous suspension indicated that the presence of soil particles was deterrent to effective decomposition of MCPA. On the other hand, the importance of ultrasonic irradiation to extract and subsequently decompose MCPA from soil was clearly demonstrated when the results were compared with those obtained in a dissolution experiment of model soil in water subjected to stirring instead of applying ultrasound.

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Several types of ceramic nanoparticles syntheses using power or subtle ultrasound are presented. Magnetite particles were precipitated from Fe(OH)₂ alkaline solution. Sonochemical effects on oxidation and dissolution-precipitation are investigated. We found a unique formation of nanoparticles under a cleaner-type sonication. Carbon nanoparticles were prepared from a sonochemical polymerization of benzene-derivatives in the presence of solid particles. At an intensive sonication, graphite nanoparticles were likely to form. While at a moderate and long sonication in the presence of zinc metal particles, it was found that plate-like particles were grown. In the presence of Co and Ni particles, needle-like particles were frequently formed. Subtle irradiation of ultrasound is called soft sonication. Here we pay our attention to the starting solution for preparing nanoparticles; that is, soft sonication was applied before chemical reactions to modify the structure of the starting solutions for the synthesis of spherical silica. Soft sonication enhanced the aging of starting solutions, monodispersibility of spheres, and final sphere size. From this point of view, we suspect that water and ethanol may not be well mixed at atomic level.

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A new electrospray pyrolysis method using ac voltage was developed to aim for the mass production of nanoparticle. In the electrospray method, ac high voltage with 60Hz was supplied to the spray nozzle instead of dc high voltage and the generation of droplets was synchronized with ac frequency. Solutions of ethyl alcohol with zinc nitrate and thiourea was used as the source to produce ZnS nanoparticles. ZnS particles were also produced by dc electrospray pyrolysis to estimate the performance of the new method.
The particles prepared by ac electrospray were the mixture of the cubic ZnS, solid S and solid Zn and their shapes were oval. Yields of particle production were drastically improved by ac eletrospray. The particle sizes and distributions cloud be smaller by the synchronization of droplet ejection and ac frequency.

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Chemical vapor deposition (CVD) of carbon is applied to the manufacture of the C-SiC functionally graded material and the C/C composite. Propane is often used as carbon source. Since propane is rapidly decomposed in the gas phase, a comprehensive model of the gas-phase reactions is required for designing and controlling the CVD processes. Experiments and numerical simulation of propane pyrolysis at 1010°C, 6.7 kPa and a propane pressure of 0.1-3 kPa in helium were carried out. The carbon deposition rate and gaseous product composition were measured. Involved in propane pyrolysis, 651 elementary reactions were taken from the database. First, the number of the chemical species was limited by considering the heaviest component, butane, detected in the experiments. The number of elementary reactions was reduced by ignoring the stereoisomerism of C₄ compounds. The numerical simulation was carried out for 453 reactions and 57 species. Based on the calculated results, the elementary reactions having low reaction rates under the actual reaction conditions were discarded. Then, by grouping isomers at partial equilibrium or having similar behavior and replacing consecutive reactions by the rate-determining step, a 55-reaction model was built. By examining the contribution of each reaction to the material balance of each species, important reactions were extracted. The contribution of each reaction to the deposition rate was also examined by repeating removal of one reaction and calculation of carbon deposition rate. Finally a 26-reaction model of propane pyrolysis was developed. The proposed model was able to reproduce the experimental results. The procedure of reduction of the elementary reaction model presented in this study is expected to apply to other CVD reaction systems.

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Microwave heating can be considered as the regeneration method of adsorbent in the removal of very low concentration VOCs. In this study, the effect of addition of cobalt oxide on microwave heating of adsorbent bed was investigated. Oxidation of ethylene by Co-modified MORs under microwave irradiation was also tested. In the case of Co-modified MOR prepared by impregnation method, the addition of Co₃O₄ did not have an effect on microwave heating. However the addition of Co₃O₄ promoted microwave heating when Co₃O₄ and NaMOR were mixed mechanically. In addition, pelletized mixture is heated to higher temperature with fast rate of temperature rising as compared with powder type mixture. In the case of the pelletized mixture with 75 wt% Co₃O₄, adsorbed water on NaMOR was almost desorbed during microwave irradiation. It was possible to remove ethylene on the pelletized mixture using microwave irradiation and obtain high conversion of ethylene over 93 %.

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Since fluorocarbons containing chlorine atoms deplete the ozone layer, the production of chlorinated fluorocarbons (CFCs) has been banned. At present, hundreds of thousands tons of CFCs are regarded as harmful wastes. To solve a problem, we are proposing a new process that these chlorinated wastes are converted into useful compounds. Decomposition occurred by just bubbling CFC12 gas into alkali-alcohol solvents under UV irradiation. The conversion of dichlorodifluoromethane (CFC12) to 1,1-difluorodimethyl ether (DDE) was carried out in methanol-NaOH solution under UV irradiation. It is a consecutive reaction in a solution through two steps: the first step is the photo-dechlorination of CFC12 to chlorodifluoromethane (HCFC22), and the second is HCFC22 to DDE. At each step, NaCl is produced. In this work, we are mainly interested in the first step of CFC12 photo-dechlorination. Concentrations of CFC12 into solution were measured with gas chromatography. Experiments at 5.0°C showed that the flow rate of the gas mixture above 2.0 l/min did not affect the reaction. This means that the reaction was rate limiting above the flow rate 2.0 l/min. The reaction rate of photo-dechlorination was found to be proportional to partial pressure of CFC12 and square root of UV light intensity. Concentration of NaOH between 1.0 and 2.0 mol/l has no effects on reaction rate.

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The ever growing ULSI device integration now requires ultra thin films as low as several nano-meter level. The so-called layer by layer growth is the ideal for making thin films for these requirements but island growth often occurred in metal CVD to deposit Al, W and Cu thin films on barrier layers, mostly composed of TiN or Ta/TaN films. We have made in-situ monitoring of initial nucleation behavior using laser light reflectivity measurement. This technique enables us to monitor the incubation period during which no nuclei formation is observed. The surface adsorbates during the incubation period was monitored by XPS and we found that the reactivity of initial surface and the film precursor is determining the incubation period.

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An aluminum plate has high heat conductivity and a porous layer with high surface area can be formed on it by anodizing. This porous layer is suitable for the catalyst support, especially for the catalyst support of the micro reaction process. In this study, a micro reactor was manufactured using a metal aluminum plate. Flow channels those with 500 m to 1500 µm width, 500 µm to 1500 µm depth and 50 mm length were manufactured on the aluminum plate(JIS A1050) by a mechanical process. The wall of channels was anodized in oxalic acid solution. The pore widening treatment and the hot water treatment were conducted after the anodizing, and then a layer of porous aluminum oxide was formed. It was found that the thickness of anodized layer was homogeneous on the wall of channel. Cu and Zn catalysts were impregnated on this anodized layer. Effects the channel width and depth of formation of catalysts were evaluated. From the results of characterization of the catalysts, it was found that homogeneous distribution of catalyst species on the wall was accomplished. This aluminum plate with catalyst channel was lidded with another aluminum plate and used as a micro reactor. Methanol steam reforming was conducted using this reactor. High activity was attained in comparison with the conventional plate type anodized aluminum catalyst.

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Microchannel whose one side wall consists of anode and the other side is cathode was fabricated for the particle manipulation such as separation and classification. Stainless steel, SUS304 and phosphor bronze copper, C5191P were employed as the electrodes. The upper and lower walls consist of glass or acrylic resin. The examined width and depth of the channel were 400 µm and 100 µm, respectively. The diameters of suspended monodisperse particles (Polymethyl methacrylate, 1,190 kg/m³) in ion-exchanged water are 1.8, 5, 10 µm, respectively. The particle behavior was recorded in a personal computer (PC) through microscope equipped with CCD module. When 2 volts were applied between the electrodes, larger particles with a surfactant moved to the cathode slowly while smaller particles always moved to anode. On the other hand, particles dispersed without surfactant always moved to anode regardless of the size. The particle migration led to concentration in the half side of the channel. It supposes that the former migration was caused by electro osmotic flow (EOF) near lower wall rather than by electrophoresis since particles appeared to be settled down and the vertical movement was observed near the edge of concentrated region. The EOF is generally utilized to convey the fluids in µ-TAS by applying high voltage (typically 1 - 10 kV) in the main stream direction. In the device newly developed, on the other hand, it seems that the extremely short distance between electrodes allowed the low voltage to cause the strong EOF. Further, it should be noted that the production of oxygen and hydrogen was not observed practically due to the low voltage. The feasibility as a new separator and classifier was shown by feeding suspensions into the channel. The many advantages of the device are described and the direction of further study is indicated.

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Biological systems are the excellent functional systems, which includes sensing, morphological change, synthesis and conversion. Those inspire to create biomimetic artificial systems. In biological systems, compounds were synthesized by multistep enzymatic conversions, which its efficiency cannot be reproduced in bulk chemical reaction. Here we show that efficient multistep enzymatic reaction can be achieved within microreaction system. We describe preparation of enzyme-immobilized tandem microcapillary reactor, then show the performance of this tandem microreactor which mimics high efficiency of multistep enzyme reaction in biological systems.We have chosen three step enzymatic conversion reaction of citric acid into L-lactic acid as a model case. First, we prepared three enzyme immobilized microreactors, which immobilize citrate lyase, oxalacetic acid decarboxylase, and L-lactic dehydrogenase, respectively. The enzymes were immobilized by sol-gel surface modification method. Resulting microreactors were connected in tandem, to perform multistep reactions. Reaction was performed by loading a 100 mM solution of sodium citrate buffer (pH7.4) by pumping, and evaluated by HPLC analysis of the product. The microreactor could convert citrate into L-lactate even at a flow rate of 10 ml/min. This result demonstrates that our microreactor can perform multistep reaction efficiently.

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A three dimensional microchannel reactor with a settler has been designed through high-precision technology. This device is composed of three different plates with channel and base made of stainless and three quartz glasses. Three plates are named as follows; joining plate, reaction plate and separation plate. A three dimensional microchannel reactor has two advantages. One is that this device can separate heavy-phase and light-phase completely by settler. The other is that it can change channel pattern by changing reaction plate. Five channel patterns were made; straight pattern, straight with circle pattern, small wave pattern, notches pattern and big wave pattern. When the extraction of Cu²⁺ was examined using various channel pattern, the flow condition was observed and extraction rate was compared. The following results were obtained. 1) The microchannel reactor with settler could completely separate heavy-phase and light-phase over a wide flow range of 0.0005-0.012 ml/s. 2) When flow rate was high, a flow condition is not detected clearly in all channel patterns. When flow rate was low, the liquid-liquid interface was observed clearly. The direction of the interface was perpendicular to the flow direction of the liquids. Flow condition of small distance phase was observed in big wave pattern, small wave pattern and notches pattern. 3) Flow condition of small distance phase has a character that extraction rate is fast in big wave pattern.

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Microfluidic system has superior controllability of fluidics. Herein we have developed a novel separation method for the complexes formed in microchannel, and application for DNA sensor. This method is based on the molecular sieving effect which is achieved by the superior controllability of fluidics. By the use of confocal fluorescence microscopy observation and computer simulation, we have confirmed that the laminar secondary flow at the curing part of microchannel enables this microfluidic separation. Also in this study, we have applied this molecular sieving effect for sequence-selective DNA sensor. As the result of this measurement, the response of complementary sequence target DNA was higher than non-complementary sequence. Moreover, in comparison with different length complementary sequence target, the response of longer target was higher. This method does not require immobilization of probe or target DNA, just simply inject solutions into microchannel and all reactions performed in the liquid phase. Such features might enable lowering the experimental error and difference in data by operators.

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Recently, microreactors have attracted considerable attention in homogeneous reaction system. For the crystallization in microreactor, however, the channel blockage is a key issue for the continuous operation. In this study, the crystallization of calcium carbonate (CaCO₃), which was selected as a model reaction, was carried out in liquid flow along the microchannel. As a result, the channel blockage occurred instantaneously due to the deposition of particles to the channel wall. In order to prevent the channel blockage, novel designed microreactor was fabricated to obtain the particles in droplets. Soybean oil was introduced into microchannel as a continuous phase. A droplet was formed by a coalescence of Na₂CO₃ solution and CaCl₂ solution at the tip of nozzles and then the nucleation and the crystal growth of CaCO₃ particles were observed in the droplet. In this system, CaCO₃ particles could be formed continuously without channel blockage. This novel microreactor was applied to the synthesis of Ag nanoparticles. When the Ag nanoparticles were synthesized in the microreactor, the particle agglomeration was more suppressed and the distribution of particle size became narrower as compared with the particles produced in a beaker.

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