This paper reports on the experimental investigation carried out to evaluate mass transfer characteristics of a hydro-dynamically-induced multi-stage bubble column. As conventional normal bubble column could not meet the high mass transfer rate, this novel bubble column has been conceived, designed and fabricated as a wet scrubber for the control of air pollution; in addition it has versatile use as a gas–liquid contactor in chemical processing industries. Chemical methods have been used to characterize the mass transfer of the novel multi-stage bubble column. A liquid side mass transfer coefficient and a volumetric mass transfer coefficient have been found to be effective and improved from the previous work for such an improved gas–liquid contactor.

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The Effects of off-bottom clearance on Macro instabilities (low frequency fluctuations of flow) generated by a Rushton turbine in a fully baffled cylindrical flat-bottomed vessel was investigated by laser Doppler velocimetry and a laser sheet flow visualization. The frequency of Macro instabilities depended on off-bottom clearance C, that is, the volume between the impeller and the bottom or the surface. Two frequencies of Macro instabilities above and below the impeller in the range of 0.3D ≤ C ≤ 0.8D showed linear correlation to the off-bottom clearance C, where D is the vessel diameter. However, for C < 0.3D or C > 0.8D, the frequencies did not follow the linear correlation to the off-bottom clearance C.

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Surfactant drag reduction is a promising technology to reduce the pumping power of district heating–cooling systems. Many investigations have been reported to give a clear prospect of the drag-reducing phenomenon. However, the mechanism of surfactant drag reduction and the microstructure of surfactant micelles are still left unknown. This study aims to provide an experimental evidence of the effect of counter-ions on the micelle structure and the surfactant drag reduction in a pipe flow. The present authors have been investigating the surfactant drag reduction with a cationic surfactant with suitable counter-ions (sodium salicylate). The effect of the molar ratio of the counter-ion to the cationic surfactant is discussed using the experimental results on the drag reduction in a turbulent pipe flow, on the micelle size and on the shear thinning–thickening viscosity. These experimental results suggest that a new drag-reducing state exists at very high molar ratios of the counter-ion to the surfactant. This new state gives a remarkable drag reduction, but shows very weak viscoelasticity. The optimum molar ratio to cause a strong viscoelasticity is (surfactant):(counter-ion) = 1:1.5, but at higher molar ratios, the elongational viscosity decreases, while high drag reduction effectiveness is kept. The micelle structure could be changed at higher counter-ion molar ratio, but this new structure may also be effective for drag reduction.

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New correlations have been developed to represent the data on continuous phase axial mixing coefficients in terms of all the operating and fundamental variables. Published experimental results along with the present data consisting of seven liquid–liquid systems obtained from eight different sources covering a wide range of variables were used for the development of correlations. The predictive ability of the present proposed correlations are found to be good, and the statistical error analyses are reported.

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The mixing efficiency of a simple, 32-layered micromixer was evaluated. Two liquids are each divided into 16 streams, and converged into 32 laminar flows by merging five times transversely, in turn. Miscible fluids can be mixed rapidly; and, 31 stable interfaces of fluid layers can be produced for immiscible fluids. This process is expected to increase the scope of high-speed chemical reactions and material syntheses. The micromixer used in this study was fabricated using PMMA plates which are easily processed. Mixing efficiency was evaluated by confocal fluorescence microscopy and computational fluid dynamics simulation. The results indicate that about 90% mixing was achieved within 1 s after the streams had been merged at a flow rate of 150 μl/min.

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In the ultrasonic atomization, the contribution of evaporation to the rate of accompanying liquid was examined. Pure water was used as the liquid to be atomized and nitrogen was used as the carrier gas to accompany the atomized droplets. The velocity, the humidity (dry or wet) and the outlet height of carrier gas were changed, and the rate of accompanying liquid was measured.
The evaporation rate increased with increasing gas velocity but was unchanged at the higher gas velocity. The evaporation rate was higher at the high outlet of carrier gas than at the low one. The contribution of evaporation became smaller with increasing gas velocity.

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The effects of seven kinds of impurities on the solvent-mediated transformation of crystal polymorphs of a drug substance AE1-923 were investigated. AE1-923 was developed for an indication of pollakiuria and pain. It has three polymorphs, namely the unstable A-form, the metastable B-form and the stable C-form. The impurities tested were the starting compounds, the reaction reagents and the intermediates in the synthesis of AE1-923. One of the impurities, an intermediate AE1-923ME (methylester of AE1-923), inhibited the solvent-mediated polymorph transformation of the B-form to the C-form, although the transformation of the A-form to the B-form was not inhibited. The other impurities had no effect on the two steps of polymorph transformation. The inhibitory effect of AE1-923ME that was evaluated by the overall transformation rate constant k_c exponentially increased with an increase in the concentration of AE1-923ME. AE1-923ME of 0.5 wt% completely suppressed the nucleation of the stable C-form crystals. However, crystal growth of the C-form was not inhibited.

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The permeation of gasoline vapor was studied using triethylene glycol (TEG) liquid membranes, which were supported on the surface of a microporous hydrophobic membrane. The vapor permeation experiments were conducted using a flat-type membrane cell under the conditions of atmospheric pressure on the feed side and a vacuum on the permeate side. A hydrocarbon mixed vapor was fed into the membrane cell by a carrier gas. The feed vapor consisted of C5–C8 hydrocarbons, in which 72–87% was aromatic. The vapor that permeated through the TEG liquid membrane was 98–99% aromatic. The TEG liquid membrane showed preferential permeation for aromatic components in the gasoline vapor. The selectivities for C6 and C7 aromatic hydrocarbons over paraffin hydrocarbons were 47 and 15, respectively.

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Three kinds of polymeric gels are copolymerized with a photo-crosslinkable prepolymer, ENTP-4000 or ENT-3400, and a functional monomer, acrylic acid AA, diethylacrylamide DEAA or NIPA. The applicability of the gel as an adsorbent for the temperature-swing adsorption (TSA) process was investigated with using nonionic surfactant Triton as a model adsorbate. The hydrophobic ENTP-AA gel was not suitable as an adsorbent for TSA because the desorption of surfactant from the gel was insufficient. On the other hand, both ENT-DEAA and ENT-NIPA gels showed reversible change in the adsorbed amount in the adsorption–desorption cycle. It was concluded that the ENT-DEAA and ENT-NIPA gels were promising for the TSA process. The equilibrated adsorbed amount of Triton increased with an increase in hydrophobicity of the surfactant and/or the temperature-sensitive functional group. The adsorption and desorption rates were much smaller than those of swelling and shrinking. These results indicate the importance of molecular design of the photo-crosslinked adsorbent gel and chemical engineering approach for practical application of TSA.

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N-Isopropylacrylamide (NIPA) gel was prepared by free radical polymerization in the presence of tributyl phosphate (TBP) as the extractant species of phenols. Homogeneous hydrogel was found to form at 333 K in methanol and the concentration of crosslinker (N,N′-methylenebisacrylamide) of 86 mM. The resulting NIPA gel incorporated with TBP was applied to the removal of phenol from aqueous solution. The removal efficiency of phenol using the hydrogel was greatly enhanced by the incorporation of TBP. The liquid–liquid solvent extraction of phenol using TBP was examined for the comparison of the distribution ratio D. From the proportional dependence of D on the amount of TBP, phenol was found to form 1:1 complexes with TBP both in NIPA gel and liquid–liquid solvent extraction. NIPA gel incorporated with TBP at a molar ratio [TBP]/[NIPA] = 1 exhibited considerably high removal efficiency (D = 74) compared to that obtained in the liquid–liquid solvent extraction.

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We found a new method of optical resolution based on the crystal size difference of the D- and L-crystals. In the crystallization from DL-Asn aqueous solution, enantio-differentiating additive (L-Cys) reduced only the L-crystals. The large D-crystals and the small L-crystals can be separated very easily, by sieving, for instance.

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The effects of the solute properties in aqueous solutions on the separation characteristics in ultrasonic atomization were experimentally examined. For the aqueous solutions of monohydric alcohols (methanol, ethanol and 1-propanol) and ketone (2-butanone), the content in the accompanying liquid was larger than that in the residual solution. For the aqueous solutions of dihydric alcohol (propylene glycol), trihydric alcohol (glycerol) and amides (formamide and acetamide), on the other hand, the content in the accompanied liquid was smaller. From these, it was considered that the hydrophilic and hydrophobic properties of solute molecules govern the separation characteristics in ultrasonic atomization. For the aqueous solutions of carboxylic acids (acetic acid and propioloc acid) and inorganic salts (Li₂SO₄, Na₂SO₄, K₂SO₄, Rb₂SO₄ and Cs₂SO₄), the content in the accompanied liquid was the same as that in the residual solution. These results indicate that ionized molecules in water were not separated by ultrasonic atomization.

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Experimental and numerical studies have been conducted on the effect of rotor blades in a mechanical impact mill. The flow fields and particle trajectories around the rotor were calculated using the CFD software, Fluent. Calcium carbonate and β-cyclodextrin particles pulverized in the mill with various blade angles were characterized by particle size distribution analyses and X-ray diffraction (XRD). The optimum blade angle for changing crystalline property of the product is different from that required for size reduction. Fine particles are produced when the blades are inclined forwards at an angle of 30 degrees while the blades inclined at 15 degrees promote the efficient change in crystallinity of the product. From the CFD simulations, size reduction is related to the amount of normal impact energy of particles colliding with the blade and stator walls when the particles pass through the pulverizing zone. The change in the crystallinity of particles is related to the amount of tangential impact energy applied to the particles in the pulverizing zone.

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As a sequel to the previous works of Huang and Lee (Huang et al., 1998, 2001; Lee and Huang, 2001), this work presents a new on-line method for identifying block-oriented models of Hammerstein-type or Wiener-type nonlinear processes from a relay feedback experiment. The identification of linear subsystem is focused. A simple transfer function of linear subsystem is determined by using an adjustable PI controller to develop a loop transfer function that has the dynamics of an integrator-plus-dead-time (IPDT) process. The static nonlinearity is represented by an invertible. Finally, the controller design using the identified model is illustrated.

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Failure diagnosis of flowmeters based on control limits has been developed as a method to identify faulty flowmeters, which should be calibrated during a maintenance period, during plant operation. This method is very useful for the diagnosis of flowmeters having faulty errors with magnitudes greater than three times of their control limits. However, there is a shortcoming that the diagnostic results given by this method often miss giving alarms when they should, or give false diagnoses, for faulty errors with magnitudes less than three times of their control limits. In this study, the diagnostic results given by this method during plant operation are not adopted in a straightforward manner. Instead, at least one flowmeter is selected and calibrated during a maintenance period, to identify the true value of a flow rate. As a result, the diagnostic accuracy can be improved by performing a second diagnosis using the calibrated values of the flow rates. Furthermore, the performance of the method presented is demonstrated by numerical experiments on a simplified refinery model containing 11 flowmeters.

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Previously, we proposed the Antigen-mediated genetically modified cell amplification (AMEGA) system, which can selectively amplify gene-transduced cells without antibiotic selection. While the original AMEGA system employed two vectors encoding a pair of antibody/receptor chimeras and a gene of interest, the use of two virions resulted in low co-transduction efficiency and time-consuming selection. Here we show an improved AMEGA system, where the three genes are linked in tandem with internal ribosomal entry sites in a single vector. We used gp130 chimeras whose extracellular domain was replaced with either V_H or V_L region of anti-hen egg lysozyme (HEL) antibody HyHEL-10 and D2 domain of erythropoietin receptor. The constructed vector was retrovirally transduced to IL-3-dependent Ba/F3 cells followed by HEL selection in the absence of IL-3. The resultant transduction efficiency increased by ~100-fold compared to the previous two-vector system, which results in a much shorter selection period.

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Phaeodactylum tricornutum is a marine diatom belonging to the Bacillariophyceae class of algae and contains 7–35 wt% of lipids in the forms of myristic acid, eicosapentaenic acid and others. Due to the high growth rate, P. tricornutum attracts interest as a substitute for the fossil hydrocarbons of petroleum as an energy source and as a way of carbon dioxide fixation.
In this study, P. tricornutum was cultivated in batch operation in artificial seawater with granular activated carbon (GAC) and activated carbon fiber (ACF) as the adherent material. The growth rate of P. tricornutum was increased with the addition of ACF, compared to the case of GAC and no culture adherent material used. We examined the optimum culture conditions of P. tricornutum in terms of the biomass concentration and growth rate, in terms of the quantity of ACF addition and concentration of carbon dioxide. It was found from the experimental investigation that the optimum operating condition of fixation of carbon dioxide concentration was 5–10% and downward in the air.

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Fundamental reaction behavior in dechlorination of concentrated monochloroalkanes (methyl, ethyl, n-propyl, and iso-propyl chloride), whose concentrations were set at as high as 15–20 times the solubility at room temperature, was investigated at various hydrothermal conditions under a saturated vapor pressure up to 380°C. The optimum conditions for the dechlorination treatment and solvent effects on the reactions have been discussed based on the results obtained under specific conditions of temperature, reaction time, stirring rate, solvent states (e.g., volume ratio of chloride to solvent, concentration of additive alkali or alcohol, filling ratio of solution in a vessel) on the dechlorination ratio. All the chlorides studied in the present work were easily dechlorinated by hydrolysis, and the alkyl groups were preserved under hydrothermal conditions in the “subcritical” region. These results indicate the optimum conditions for hydrothermal dechlorination and that the products can be controlled in the yield and ether formation by the concentration of the additives in the solvent.

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