Kenji Iimura

The effect of terephthalic acid particle properties on particle fracture phenomena was investigated in this study. Furthermore, to evaluate the fracture characteristics in real process, the effect of the particle impact angle on particle fracture phenomena was also investigated. The results of this study indicated that: (i) the crystallite size correlated with the fracture stress of the particle; (ii) the crystallite size also showed a correlation with the critical fracture velocity and the kinetic energy of the particle; and (iii) the particle fractured more easily at impact angles under 45°.

A new method for determining the liquidus and solidus pressures of mixtures of C18's unsaturated fatty acids at constant temperatures was proposed, and three binary isothermal SLE data under high-pressure were systematically measured in this study. The liquidus and solidus temperatures of oleic acid, linoleic acid and alpha-linolenic acid commonly rise above their normal melting temperatures when pressure is increased. This new high-pressure experimental system can closely track pressure in real time during pressure swinging changes, making it simple to measure liquidus and solidus pressures using this dynamic measurement method due to fast responsiveness of pressure. In this study, the liquidus pressures of pure oleic acid, linoleic acid, alpha-linolenic acid and three binary mixtures consisted of oleic acid, linoleic acid alpha-linolenic acid at constant temperature were determined. The isothermal SLE were first correlated based on a simple thermodynamic model. (C) 2021 Elsevier Ltd.

In this study, a novel reversible control method of particle dispersion/flocculation for nonaqueous solvent was developed. Titanium oxide was used as sample powder. Cyclopentasiloxane was used as solvent and Polyoxyethylene polyalkylsiloxane was used as a dispersant. First, a well-dispersed slurry was prepared by adding dispersant. After preparation, alcoholic amphiphilic molecule was added to the well-dispersed slurry to convert it from liquid to a gel-like consistency, which was caused by the hydrogen bond of dispersant on the surface of the particles. The resultant gel could easily be changed to liquid state by shaking. In addition, the slurry reverted back to gel state after a certain period of time. It was found that the relative permittivity and the additive amount of amphiphilic molecule has an influence on the strength of the gel.

A nickel-metal hydride (Ni-MH) prototype battery completely immersed in an aqueous electrolyte solution of KOH under high-pressure was fabricated to examine the effects of high-pressure on the quality of Ni-MH batteries. The small battery cell comprised positive and negative electrode materials, as used in electric vehicles, and an Ag/AgO reference electrode. The electric capacity of the Ni-MH battery was measured at different temperatures and pressures with small currents and charge/discharge voltages of 1.6-1.0 V. High-pressure was found to clearly and effectively enhance the electric capacity of the Ni-MH battery at larger currents. The considerable effect of high-pressure on the Ni-MH battery was elucidated by the change in internal resistance during the charge/discharge cycle life experiment, indicating that the voltage of the positive electrode did not appreciably change under high-pressure compared to that of the negative electrode. Moreover, the use of large currents in rapid charge/discharge cycle tests at high pressures of up to 30 MPa resulted in charge/discharge cycles that were five times faster and a quick recovery of capacity was achieved in the 0.5-2.1 V range.

We fabricated a surface acoustic wave (SAW) actuator by patterning an interdigital transducer (IDT) made of Al film on a LiNbO3 substrate and investigated its transport characteristics with powders of spherical copper, spherical glass, spherical polyethylene, and angular alumina particles with sizes of about 100 μm. The IDT had a 2 mm pitch size, 10 mm aperture, and 10 stripline pairs. It was found that the glass, polyethylene, and alumina powders that could not be transported when the actuator was horizontal could be transported by tilting the actuator, i.e., the powder transport path. It was also found that the powder movement response times with SAWs were shorter than 50 ms when the actuator, tilted at suitable angles of 0°, 6°, 15°, and 26°, transported the copper, glass, polyethylene, and alumina powders, respectively. Then, we fabricated miniature feeders by mounting hoppers on SAW actuators tilted at the above angles and investigated their powder feed characteristics. It was found that, when the feeders were driven for 50 ms at an electric power of 1 W, the fed weights of the copper and glass powders, which did not have flowability problems, were 2.3 and 0.9 mg, respectively.

In this study, the fracture phenomenon of particle impacting with wall was directly observed using a high-speed camera. The results from the experiments indicate that the fracture behavior differs in the impact angle, and there are two types of fracture mode: one is with “Break” and the other with “Chip”. In case of low impact angle condition (less than 70°), there is only “Chip” mode. Furthermore, the effect of the particle impact angle on particle fracture phenomena was also investigated. The results of this study indicate that the particle fracture velocity almost is the same value at impact angles under 45° or higher.

Micellization of the Gemini surfactant sodium dilauramidoglutamide lysine (SDGL) in the presence of an antihistamine drug, diphenhydramine hydrochloride (DPC) was investigated. The anionic surfactant sodium dodecyl sulfate (SDS) was used for comparison. DPC significantly decreased the critical micelle concentration (cmc) of both SDGL and SDS in aqueous media and increasing the DPC concentration decreased the pyrene excimer/monomer polarity ratio in SDGL micelles but increased it in SDS micelles, suggesting that SDGL and SDS micelles have different shapes. The counterion binding and binding constant values reveal that SDGL micelles interact more strongly with DPC than SDS micelles. Thus, DPC, as an organic counterion, can enhance surfactant micellization. The evaluation of the solubility of a poorly water-soluble drug (clotrimazole) in SDGL and SDS micelles containing DPC revealed that the drug was more soluble in SDS micelles than SDGL micelles, indicating that the cmc and the shape and size of micelles are essential factors for controlling drug solubilization.

Ion exchangeable inorganic fibers based on sodium silicate have been successfully developed. The fibers have the ion exchange capacity of 83.8 meq·100 g−1 which is comparable to that of ion-exchangeable resin. Absorbing glass mat (AGM) for separators in lead-acid batteries was also successfully prepared with ion-exchangeable sodium silicate fibers. It was clarified by charge/discharge cycle test and morphological observation with scanning electron microscopy that the ion exchangeable AGM can inhibit the precipitation of PbSO4 particles on the surface of electrodes and consequently reduces the deterioration in coulomb efficiency during repetitive cycles. Furthermore it was also clarified that ion-exchangeable AGM can inhibit the precipitation of PbSO4 in separator itself notably. This will allow the reduction of thickness of separator and downsizing of lead battery body.

The effect of terephthalic acid particle properties on particle fracture phenomena was investigated in this study. Furthermore, to evaluate the fracture characteristics in real process, the effect of the particle impact angle on particle fracture phenomena was also investigated. The results of this study indicated that: (i) the crystallite particle size correlated with the fracture stress of the particle; (ii) the crystallite particle size also showed a correlation with the critical fracture velocity and the kinetic energy of the particle; and (iii) the particle fractured more easily at impact angles under 45°.

In this study, the effect of multivalent ions on ionic crosslinking of polyelectrolytes adsorbed on particle was investigated. Ammonium polycarboxylate, one of the typical polyelectrolytes, was used as a dispersant. Zinc oxide and titanium oxide was used as sample powder. A well-dispersed slurry was prepared by adding polyelectrolytes as the dispersant beforehand. Thereafter, multivalent cations were added to the slurry to convert it from liquid to a gel-like consistency, which was caused by the ionic crosslinking of polyelectrolytes adsorbing on the surface of the particles. It was found that the ionic radius of adding multivalent cation has an influence on the strength of the gel. It was also shown that this method was effective for prevention of density segregation during sedimentation.

In this study, a novel reversible control method for particle dispersion/flocculation was developed with the dual aim of preventing settling/sedimentation during storage and maintaining low viscosity in use. First, a well dispersed slurry was prepared by adding polyelectrolytes as dispersant. After preparation, multivalent cations were added to the slurry. By adding multivalent cations, the well dispersed slurry was changed to gel state because of the ionic crosslinking of polyelectrolytes adsorbing on the surface of the particles. The resultant gel was very soft and could easily be changed to liquid state by shaking. In addition, the slurry reverted back to gel state after a certain period of time. The softness of gel can be controlled by additive amount of multivalent cations. Thereby, a novel reversible control method for particle dispersion state was successfully developed.

We examined the degradation of aqueous phenol by ozonation in an aerated mixing vessel, which was combined with a fixed-bed reactor packed with high-silica zeolite (HSZ) pellets. Ozone-containing oxygen gas was introduced as fine bubbles through a sparger placed in the aerated mixing vessel, whereas the aqueous phenol solution was circulated between the vessel and the reactor. Measurements of transient changes in the concentration of both phenol and total organic carbon in the treated solution revealed that the degradation of phenol or total organic carbon by ozonation was enhanced by the presence of HSZ because both phenol and ozone could adsorb on the hydrophobic micropores. As a result of quantitative analysis of the treated solution, it was found that catechol, hydroquinone, humic acid, and maleic acid were the possible reaction intermediates during ozonation of aqueous phenol employing HSZ.

In this study, the mechanism of granule fracture under biaxial compression was investigated through both experimental and simulation methods. The results of the experiment indicate that the fracture behavior differs depending on the number of compressional axes. The fracture load under the biaxial condition is smaller than that under the uniaxial condition because in the latter, the compressed granule can be deformed planarly, whereas in the former, the compressed granule can be deformed into only one axial direction that is not compressed. To investigate this phenomenon in detail, finite-element method (FEM) analysis was used to analyze the tensile stress inside granules. The results of the FEM simulation indicate that the dominant factor in fracture phenomenon is tensile stress at the center of granules. From these results, it will be possible to theoretically predict, without any complicated experiments, the likelihood of fracture in granules.

Xerogels of large specific surface area have been successfully prepared by optimizing sol-gel process without any templates. It was found that the optimum solvent to obtain gels of large specific surface area is 1-propanol and the optimum molar ratio of solvent to alkoxide is 10. It was also clarified that the consecutive addition of water to reaction system by introducing humidified air is critical to specific surface area and that with humidified air the less initial content of water can provide gel of larger specific surface area. Consequently silica gel with specific surface area of 1869 m2/g could be obtained. Titania gel with specific surface area of 597 m2/g was successfully prepared by using ammonium acetate as catalyst together with above mentioned strategy. Obtained titania gel was used as support material of Ni nanoparticle and the catalytic activity was tested then compared with commercially available non-porous titania fine particle and commercially available silica gel. As a result, the significance of catalyst-support interaction and improvement of loading amount of catalyst nanoparticles attributed to porosity were confirmed.

SnO2 quantum dot was successfully synthesized at ambient temperature via ozone bubbling to suspension including Sn6O4(OH)4 under pH of 12. It was clarified that use of SnF2 as starting material enables to obtain clear and stable SnO2 quantum dot suspension. Possible formation mechanism of quantum dot was proposed and shift of fluorescence was predicted with use of varied basic solution for neutralization and pH adjustment based on the hypothesis that shift of fluorescence is attributed to change in size. And this prediction was confirmed by experiment. Finally addition of Zn as dopant gave improved luminescence intensity without shift of fluorescence. SnO2 quantum dot developed in this work does not include any cadmium, thus application as alternative to conventional CdSe and CdS is expected.

Centrifugal spinning process with duplex tube nozzle for the fabrication of core-shell structured edible fiber was successfully developed. Using maltose enabled fibers to be relatively stable against humidity of air. Fat-soluble materials could be successfully encapsulated by the employment of domain-matrix structure where maltose aqueous solution is continuous phase and oil is dispersed phase. In order to protect encapsulated material from oxidation or leakage, core-shell structured fiber, where domain-matrix structure fibers were enwrapped by maltose shell, was developed. The required condition to obtain core-shell structure was considered based on Hagen-Poiseuille equation, and the ratio of cross section averaged linear velocities of 0.97 was accomplished. Fluorescent microscopy confirmed the core-shell structure and SEM observation revealed that domain-matrix structure fibers without shell had rough surface probably due to the detachment of domain oil phase, by contrast core-shell structured fibers had quite smooth surface. This may be attributed to the protection from detachment of oil phase by shell material, which was supported by the result of pyrene elution experiment.

In this study, a novel reversible control method for particle dispersion/flocculation was developed. We found that the conformation of a polymer with solubility pressure dependencies on the side chain changed from random coil to fibril-like with ambient pressure. On the contrary, as we reported in our previous paper, the dispersion state of slurry changes with changes in the conformation of adsorbed polymers. Based on these results, we hypothesized that the dispersion state of the slurry can be reversibly controlled by ambient pressure. The sample used was aqueous slurry of alumina with a sodium salt of sulfonic acid copolymer with a relative molecular mass of 10000. The results showed that the dispersion state of slurry at atmospheric pressure was flocculated with a specific additive amount of polymer. On the contrary, after pressurization, the dispersion state was changed into a well dispersion state. Therefore, it was confirmed that the slurry was responsible for the pressure thereby, a novel reversible control method for particle dispersion state was successfully developed.

The recent attention to energy-saving housing has increased demand for high-performance heat insulators. Among several heat insulators, inorganic fibrous heat-insulators have various merits, but production costs are still high. This work proposes a fabrication process of water glass fibers by centrifugal spinning using a concentrated aqueous solution of sodium silicate as spinning solution. It was found that fiber thickness and distribution are strongly affected by the process parameters, and that larger centrifugal gravity provides thinner and more uniform fibers. In contrast, the viscosity of spinning solution scarcely affected the thickness and uniformity of fibers, and a spinning solution with viscosity of more than 3 Pa.s and less than 150 Pa.s gave fibers stably. Humidity-resistant fibers were produced by carbon dioxide gas treatment at over 100 degrees C. Thermal conductivity measurement revealed that the optimal value was 0.027W/(m.K), which is comparable to that of air in the absence of convection. This value was similar to that of commercially available glass wool, but the mass of fiber required was about one-half, which would be effective for cost reduction.

A new synthetic route to prepare yttrium barium copper oxide superconductive fibers using electrospinning in conjunction with the polymerizable complex method was developed. The as-spun fibers exhibited wool-like tactility and were 5-7 mu m thick. The fibers therefore exhibited sufficient flexibility to be fabricated into arbitrary shapes. Although the fibers shrunk and exhibited brittle tactility because of the decomposition of organic compounds during heat treatment, the fibers predominantly maintained their fibrous form. Scanning electron microscopy observations revealed the growth of metal oxide grains during sintering. Powder X-ray diffraction pattern of the annealed fibers showed good agreement with the pattern of YBa2Cu3O7-delta. Magnetic property measurements of a ground fiber sample using a superconducting quantum interference device revealed that the superconducting transition temperature of the sample was 91 K. (C) 2017 The Ceramic Society of Japan. All rights reserved.

<p>Centrifugal spinning process with duplex tube nozzle for the fabrication of core-shell structured edible fiber was successfully developed. Using maltose enabled fibers to be relatively stable against humidity of air. Fat-soluble materials could be successfully encapsulated by the employment of domain-matrix structure where maltose aqueous solution is continuous phase and oil is dispersed phase. In order to protect encapsulated material from oxidation or leakage, core-shell structured fiber, where domain-matrix structure fibers were enwrapped by maltose shell, was developed. The required condition to obtain core-shell structure was considered based on Hagen-Poiseuille equation, and the ratio of cross section averaged linear velocities of 0.97 was accomplished.</p><p>Fluorescent microscopy confirmed the core-shell structure and SEM observation revealed that domain-matrix structure fibers without shell had rough surface probably due to the detachment of domain oil phase, by contrast core-shell structured fibers had quite smooth surface. This may be attributed to the protection from detachment of oil phase by shell material, which was supported by the result of pyrene elution experiment.</p>

Flame made gray titanium oxide particles which exhibit visible light absorption were successfully prepared via reduction atmospheric flame synthesis process. It was clarified that the particles have high specific surface area and are of nanometer size as a result of FE-SEM observation and specific surface area measurement. Particle properties could be varied by controlling equivalence ratio and introducing cooling gas, and the specific surface area increased as equivalence ratio increased. It was revealed that the particles are hollow for φ ＝ 1.54，1.68 and the constituent particles of shells are quite small in size. And the introducing of cooling gas affects the color of particles attributed to the oxidation degree and the specific surface increased as well. The result of XRD spectroscopy did not clearly show the generation of any magneli phases, however the peak intensity of anatase phase decreased which suggests the repression of oxidation. It was confirmed that carbon is rarely included in products and the change in color can be attributed not to carbon but to oxygen defect as a result of Raman spectrometry. Furthermore, the measurement of electric conductivity demonstrated the drastic improvement compared to stoichiometric titanium dioxide.

Centrifugal spinning of fibers with core-shell structure was tried by developing double tube nozzle spinneret. Obtained fibers were classified into three types according to fiber size. It seems plausible to infer that thin fibers are composed of only core material and thick ones are composed of only shell material. By contrast, it was clearly confirmed by observation with optical microscope that fibers have core-shell structure for medium size range around 10μm in diameter. In order to discuss the condition to obtain core-shell structured fiber, analysis based on the Hagen-Poiseuille equation focusing on the exit velocity at tip of spinneret has been conducted. As a result, relatively good agreement in exit velocity was found between core and shell materials.

The preparation technique to obtain purely inorganic silica doped titania fibers using electrospinning together with sol-gel method was proposed. For the system without silicon doping, fibers were too brittle to form long fiber. And it was clarified that small amount of doped silicon could modify the flexibility of fibers drastically and long fibers with appropriate mechanical property could be obtained. After calcination at 500 degrees C for 2 h anatase phase was appeared and the specific surface area of fibers with composition of [Ti]/[Si] = 6 showed highest value 71.9m(2)/g among all the samples tested, which is even higher than typical fine particles. The result of decomposition experiment of Rhodamine B dye solution showed that the silica doped titania fiber has adequate photocatalytic activity to decompose organic matters. (C)2014 The Ceramic Society of Japan. All rights reserved.

The capping phenomenon means the powder adheres to the piston at the powder compression process and is one of the important causes of the powder molding trouble. The capping phenomena were difficult to discover in a compression molding process. The capping region can be detected from X-ray computed tomographic images and slipping angle of the capping area can be measured. From the experimental results, it’s clear that the capping phenomena easy to occur in the case of wider size distributed granules. So the capping phenomena can be prevented to use coarser mono-sized granules for compression molding.

When nano-sized tiny roughness is processed on a surface, the prevention of dust adhesion can be expressed by the decreasing of the van der Waals force between rugged surface and dust particle. Using nanoparticle coating on a textile, the tiny roughness can be created on a textile and the preventive effect of dust particle adhesion can be given to the cloth. This effect is applicable to working clothes etc. Generally, clothes are washed in order to remove the dirt on it, so the nanoparticle coating on a textile and the preventive effect of dust adhesion may be decreased by washing process. In order to add the functionality to the preventive effect of dust adhesion on the clothes in a practical uses, the improvement in the durability for washing is very important.<br>In this research, we confirm the preventive effect of dust adhesion and measured the effect of the number of washing on the preventive effect of dust adhesion on a textile. From our experimental results, the durability of the nanoparticle coating and the preventive effect of dust adhesion can be improved using acetalized polyvinyl alcohol treatment.

In order to determine the preparation time for slurry in ceramic manufacturing processes, the effect of the conformation of ammonium polycarboxylate, an adsorbed anionic polymeric dispersant with a molecular weight of 8000～10000, on the dispersion stability of the slurry was investigated. The slurry preparation time was varied and the effect was investigated using and hydrostatic pressure measurement. The results of the investigation showed that the conformation of adsorbed polymers changed with time from random coil to fibril-like and that it took several days for the polymers to relax completely in the slurry. Furthermore, the dispersion state of the slurry changed with the relaxing of the conformation of adsorbed polymers. The results showed that the stretching of adsorbed polymers contributed significantly to the dispersion state of the slurry. The optimum conditions of polymers for the preparation of the slurry are also discussed.

The glass substrate is coated by the silica nanoparticle suspension using dipping or spin coat method and dried in an electric oven. The glass substrate surface is covered with nanoparticle thin layer and the transparent and tiny rugged surface can be produced on a substrate. It was experimentally confirmed to prevent dust adhesion by covering the surface of the glass substrate with nanoparticle. But the reason why the prevention of particle adhesion on nanoparticle coating substrate is not clear yet. Therefore the adhesion force between particle and substrate is measured by the centrifugal method and the relation between the adhesion force and the surface roughness is discussed from experimental and theoretical point of view. The measured and calculated results by Van der Waals force show that adhesion force decreased with the increment of the surface roughness. From the results, nanoparticle coating is very effective to prevent the dust adhesion on the substrate and the various application of nanoparticle coating can be expected.

We have developed a non-contact measuring method of mixing process in the mixer using a micro focus X-ray computer tomography. And its effectiveness was demonstrated from the experimental observation of mixing process of two kinds of particle with different X-ray transmission. The cross sectional image of particle packed bed in the cylindrical container rotation type mixer was obtained from the X-ray transmission images, and the image analysis of these cross sections was performed. From the brightness of each particle image, the particle materials can be detected and obtains the ratio of each particle on every section.<br>The degree of mixing was calculated from the measured distribution of each particle, and the effect of the separation plate in the mixer on the mixing performance of a cylindrical container rotation type mixer was studied. The actual mixing state in the mixer can be measured by non-contact, and the mixing degree in the mixing process from cross-sectional image analysis can estimate directly was shown.

The hydrostatic pressure measurement method is one of the settling methods of a particle size distribution measurement. We measured the particle size distribution of the alumina slurries by this method and investigated the effects of the slurry concentration. However, the measured cumulative undersize is evaluated to be smaller than the true value at the high concentration because of the hindered settling. Therefore, in order to correct this phenomenon, we tried to use several equations of hindered settling suggested until now and the experimental equation. As a result, the particle size distribution of high concentration slurry can be measured without any dilution operations by using fitted experimental equation. Furthermore, the mean particle size measured by this method was closer to nominal value than the one measured by the laser diffraction method.

Silica fibers, which can potentially be used as filters and media for catalysts immobilization, were successfully spun via electrospinning process with precursor prepared through the sol-gel synthesis. Spinnable sols can be obtained only when the molar ratio of water to TEOS is less than 2 which is consistent with the retrospective results derived for other spinning methods. It was confirmed for the first time that the reaction time can be drastically reduced by introducing humidified air, controlled by KCl saturated aqueous solution, during sol-gel process. The size of obtained silica fibers is about 4.5 mu m and has a certain degree of flexibility and mechanical strength. Although the specific surface area of as spun fiber was 7.7 m(2)/g. which is apparently small comparing to generic silica, treatment by boiling water only for 5 min Could increase the specific Surface area to be about 500 m(2)/g. (C) 2009 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

The dispersion of agglomerates by acceleration field and impact onto cylindrical obstacles in gas phase was successfully simulated by the three-dimensional modified discrete element method qualitatively. In case of gas-phase acceleration fields, agglomerates are dispersed into much smaller fragments comparing to the dispersion in liquid-phase shear or elongation flows. The microscopic structure of agglomerates much affects the dispersibility of agglomerates and the agglomerates containing particle of single-point contact with other particles are extremely easy to be dispersed. The impact onto obstacles is more effective dispersion mechanism than acceleration fields, since rigid agglomerates, which cannot be dispersed by acceleration fields, can be dispersed at rather low gas velocity. Although when the gas velocity is very low, agglomerates are only deformed and stuck to the obstacle surface. Then the dispersion becomes significant and size of fragments decreases with the increase in gas velocity. (C) 2008 Published by Elsevier B.V. on behalf of The Society of Powder Technology Japan.

The wall effect on particle assembling structure in a particle packed bed is an important issue for powder technology. However, the detailed and systematic experimental data about the wall effect on particle assembling structure in a particle packed bed is hardly adequate yet. The distribution of the local void fraction near the container wall in a particle packed bed is measured using X-ray micro computed tomography (CT). The wall of the cylindrical vessel affects the void fraction distribution, and the distribution can be expressed by the damped oscillation function that shows the relation between the distance from the container wall and the local void fraction. The damping factor, the amplitude and two factors in our damped oscillation function varied with the ratio of particle diameter and inner diameter of the cylindrical container. Our empirical equation can be applied for X-ray CT data and also compared with the traditional experimental data by Ridgway and Tarbuck. (c) Koninklijke Brill NV, Leiden and Society of Powder Technology, Japan, 2008.

The Rankine coefficient is the ratio of the vertical pressure ( maximum principal stress) and horizontal pressure ( minimum principal stress) acting on a powder bed. The value of the Rankine coefficient is usually determined from the yield locus, which comes from the shear test results either by linear approximation using the Coulomb equation or by curve fitting using the Warren-Spring equation. Since the shape of the yield locus is obtained by approximation, the Rankine coefficient might change with the estimation method. The Rankine coefficient is an important coefficient for estimating the pressure distribution in a powder bed. However, no studies about the effect of the yield locus estimation method on the Rankine coefficient can be found in the past literature. In this paper, first we study the effect of three approximations, i.e. the Coulomb equation, the Warren-Spring equation and an equation proposed by the authors, on the Rankine coefficient. Based on these results, we investigate how the selection of the yield locus estimation method affects the Rankine coefficient. Then we compare the Rankine coefficients obtained from consolidation tests and from each of these yield loci, thereby demonstrating the validity of our proposed approximation equation.. (c) Koninklijke Brill NV, Leiden and Society of Powder Technology, Japan, 2008

A method to modify quartz particles to be a surface-active material by mechanochemical treatment was successfully developed. The obtained particles had sufficient properties for use as a particulate emulsifier. The particles prepared by mechanochemical treatment had a highly anisotropic surface, and the droplets emulsified by those particles were extremely large and stable because of their stonewall-like structure and high density. The obtained particulate emulsifier was applied to the liquid-liquid extraction process. Consequently it was clarified that the extraction rate increased 3.6 times according to the increase of interfacial area without reducing the mass transfer coefficient.

The yield locus (YL) of powder bed can be used to determine many mechanical properties of a powder such as cohesion, unconfined yield stress, stress ratio, etc. Generally, the YL of powder beds is obtained by fitting the results of shear tests to linear approximations based on the Coulomb equation or to curved approximations based on the Warren-Spring equation. Meanwhile, the yielding characteristics of a powder bed are expressed by the Roscoe condition diagram. In this diagram, the YL appears orthogonal to the normal stress axis at both ends corresponding to tensile and compressive strength. However, the YL approximated by the Coulomb or Warren-Spring equations is not orthogonal to the normal stress axis at both ends, and is not the same shape as the YL shown in Roscoe condition diagrams. Thus, the abovementioned mechanical properties obtained from the YL of a powder bed are likely to be affected by the approximate expression for the YL. Despite this, no one has investigated how the mechanical properties of powder beds such as stress ratios are affected by the approximation method for the YL. In this paper, we propose a new approximation equation for the YL that conforms both to the shape of the YL in the Roscoe condition diagrams and experimental results. Then, these YL obtained by our equation, and by the Coulomb and Warren-Spring equations are used to determine the mechanical and flow properties of powder beds. These values are compared with each other in order to discuss the validity of our equation.

This paper describes the surface topography characteristics of the (100) and (101) faces of potassium dihydrogen phosphate (KDP) crystals by using atomic force microscopy (AFM) for nanoscale observation. Fractal dimensions of the surface pattern were measured, including step height and terrace distance of KDP crystals under different supersaturation levels and dye concentrations, and the relationship between dye concentration and surface structure was examined.