An adhesion model in Distinct Element Method (DEM) for mixing of food powders having different adhesive forces was developed. It is necessary to determine which adhesive force should be applied in the DEM simulation when the particles having high adhesive force and particles having low adhesive force during mixing come in contact with each other. The simulations of mixing behavior of particles having high, low and their average adhesive forces were performed to discuss the effects of adhesive forces on mixing behavior. While, in order to compare to the mixing behavior simulated, two types of mixing experiments of salt and potato starch, and wheat flour and potato starch which have different adhesive forces were carried out. As a result, it was found that when the particles having different adhesive forces contact, the mixing behavior and mixing index of the simulation using the values of high adhesive force would be in agreement with those of the experiment.
Recently, for the pharmacokinetic control of target materials, interest has been dedicated toward polymeric nanocarrier systems with surface modifications, since these systems enables efficient drug delivery that could not be achieved by conventional formulation strategies. In this review, our latest outcomes on preparation and biopharmaceutical evaluations of surface-modified polymeric nanocarriers for pharmacokinetic control, especially oral absorption behavior, are presented. For designing the functional nanocarriers like mucoadhesive/penetrative nanoparticles, Flash nanoprecipitation (FNP) approach, a technique for promoting the nucleation over growth of precipitated particles by controlling thermodynamic and kinetic conditions, was strategically applied with combination use of polystyrene (PS)-block-polyethylene glycol or PS-block-polyacrylic acid. As the results from physicochemical, pharmacokinetic, and pharmacodynamic evaluations, either functional nanocarriers could highlight desirable characteristics to control the oral absorption behavior of model drug, cyclosporine A, possibly contributing to enhancing the biopharmaceutical properties.
Flowability of powder and granular materials is an important property to design and control the manufacturing process. A simple and low-cost technique was developed to evaluate the flowability of wet powder and granulate materials. In the proposed technique, the flowability can be evaluated by the torque for stirring wet powder with a pitched-blade paddle. In order to confirm the performance of our technique, the torques to stir the wet beads with varying moisture contents were measured. The effects of additive liquid viscosity on the torque for stirring were investigated, and the correlation between the moisture content corresponding to maximum steady torque for stirring and the additive liquid viscosity was presented.
Mechanochemistry offers sustainable synthesis of the functionalized cellulose nanofiber (CNF). In this study, changes in the microstructure of the CNF aqueous sol by planetary ball milling were investigated in terms of its rheological behavior, crystallinity, and diameter distribution. The surface activity of the CNF was additionally characterized by a pulsed nuclear magnetic resonance (NMR). A decreased thixotropy hysteresis loop observed in the 100 min−1-treated CNFs indicated a weaker interaction among the fibers, but still having a three-dimensional structure. 300 min−1 could collapse them. A decreased x-ray diffraction peak intensity observed in the 500-min−1-treated CNF could indicate a split in the fiber’s bundle as well as shredding. An increase in the wet surface area (SNMR) could indicate surface activity in the 500-min−1 milled CNF sol. Such newly formed hydroxyl groups can serve as effective reaction sites with, for example, the TiO2 precursor and perhaps favorably works to improve the photocatalytic performance.
Dynamic fields visualization method of carbon-black (CB) volume fraction ΦCB distribution in Lithium-ion battery (LIB) cathode slurry has been proposed based on electrical resistance tomography (ERT) during the manufacturing process. The proposed method consists of an impedance analyzer, a switching circuit, and ΦCB distribution imaging algorism, archiving to the measurement speed of 5 frames per second. In experiments, ΦCB distribution was visualized by the proposed method in lab-scale LIB cathode manufacturing equipment. To qualitatively evaluate the ΦCB distribution images, those images are compared with scanning electron microscope (SEM) images. This comparison shows that the ΦCB distribution images are qualitatively consistent with SEM images. In addition, in order to quantitatively evaluate the proposed method, the accuracy of reconstructed ΦCB distribution is evaluated by electromagnetic field simulations. As a result, the root mean square errors RMSE between the known ΦCB distribution and that obtained by the proposed method was less than 0.56%.
Powdery-type foundation, one of the typical makeup cosmetics, is required to form even and smooth powdered layer on the skin. Such layer is achieved by well-dispersion of foundation particles. However, particles of titanium-dioxide and iron-oxide, both of which are vital foundation components, easily aggregate on the skin. In order to solve this problem, this study aimed to develop novel low-aggregation titanium-iron oxide particle. Experiments showed that our developed particle, in which titanium dioxide is coated with iron oxide, achieved well-dispersion due to its unique structure and shape. The experiments also showed that such a particle property results in an effective coverage of color-unevenness and pores of the facial skin.
We synthesized the phosphors of (Ba1−xEux)0.79(Al1−yZny)10.9O17.14−δ (0.05 ≤ x ≤ 0.15, 0 ≤ y ≤ 0.25) by a solid-state reaction. To obtain a single phase of the phosphor, various processing conditions were investigated: particle sizes, sintering times, and optimal composition of Ba. Thus, we succeeded in synthesizing the single phase, and the brightest emission was observed at x = 0.1 for Eu. Moreover, the color changed from green to blue with the addition of the Zn2+ ion in the Al3+ site, and with an increase in the Zn content, the photoluminescence intensity increased. The color change was closely related to the crystal structure of the phosphor.
In this study, the rapid debinding of zirconia molded bodies was carried out using a superheated steam treatment. The superheated steam treatment was performed with the heating rate of 10°C/min to a holding temperature range of 500°C to 800°C. The molded body after superheated steam treatment to 800°C resulted in the residual carbon content of 0.3%. No cracking occurred in sintered bodies obtained by debinding in the superheated steam and then firing at 1500°C in air, although many large cracks occurred in sintered bodies that had been treated in air or nitrogen under similar temperature conditions. To understand the debinding behavior under the superheated steam, thermal analyses were performed with thermogravimetric. These results suggested that the debinding in superheated steam suppressed thermal runaway and the generation of pyrolysis gas caused by the chain of exothermic reactions derived from the oxidation of the forming aid. Thus, it was suggested that superheated steam treatment is highly effective for rapid debinding of molded bodies.
The purpose of this study is to evaluate the effect of tableting speed on the compression behavior of pharmaceutical powders using an R&D rotary tablet press. Cilostazol, probucol and ibuprofen were selected as model drugs, and they were mixed at a mass concentration of 20% into two base formulations composed of different excipients. The tablets were prepared at two levels of turret rotation speeds of 20 rpm and 60 rpm, and the physical properties of the tablets were evaluated. As a result, placebo tablets and cilostazol tablets had no effect on the tableting speed. However, the compressibility of probucol and ibuprofen tablets decreased and the capping tendency was observed, although the compactibility was not affected. The strain rate sensitivity (SRS) index was obtained from an out-of-die Heckel analysis, which was used to quantitatively evaluate the effect of tableting speed on the compressibility. It was found that the R&D rotary tablet press was possible to evaluate the compressibility and capping tendency by the SRS index.
Material extrusion is an additive manufacturing process that generates a three-dimensional molded product via extrusion and lamination of a plastic material. In this study, we prepared zirconia filaments, which were composites of 3Y-ZrO2 powder and thermoplastic resins. Then, we investigated the influence of the filament fluidity and molding conditions on the voids generated at the bonded interface due to poor bonding of the extruded materials. Using a filament excelling in fluidity reduced the nozzle temperature, and molding could be carried out with reduced combustion of the binder resin. Hence, the void diameters of the molded bodies were reduced to 10 μm or lesser with the nozzle temperature of 138°C and layer thickness of 100 μm, and 97–98% relative densities of the sintered bodies were indicated.
In the spent fuel reprocessing process, a mixed solution of uranyl nitrate and plutonium nitrate is converted into mixed oxide powder by the microwave heating. To evaluate the applicability to the industrial-scale and acquire the characteristics data of the microwave heating denitration of various metal nitrate aqueous solutions based on the knowledge studied in the development of laboratory-scale basic experiments, the microwave heating characteristics and metal oxide powder properties were investigated using cerium nitrate, cobalt nitrate and copper nitrate aqueous solutions. The progress rate of the denitration reaction was depended on the position, and the denitration reaction proceeded faster at the periphery than at the center. The morphologies of the synthesized products were porous and hard dry solid for cerium nitrate aqueous solution, foamed dry solid for cobalt nitrate aqueous solution, and powdery particles for copper nitrate aqueous solution. The denitration ratio and average particle size of the synthesized products increased in the order of the cerium nitrate aqueous solution, the cobalt nitrate aqueous solution, and the copper nitrate aqueous solution. The numerical simulations revealed that the periphery of the bottom surface of the metal nitrate aqueous solution was heated by microwaves. These simulation results were consistent with the experimental results in which the denitration reaction started from the periphery of the metal nitrate aqueous solution.
Carbon hollow particles (CHPs) have a lot of excellent properties such as a high specific surface area, large pore volume, and the presence of nanovoids, therefore they are applied to catalyst carriers and Li-ion batteries. However, a conventional method, hard templating method, has many problems. In this study, we developed a new method to synthesis CHPs improving thermal resistance of hollow particles (HPs) made of polymer by Friedel-Crafts hyper-cross-linking and Flame resisting treatment. This method does not require any templates which need to be removed and avoids using harmful materials such as hydrofluoric acid.
Mineral pigments which have been used since old times in Japanese paintings as coloring materials are different in color and texture depending on their particle size. Recently, there have been an increased scarcity of certain natural mineral pigments. In this research, we have pulverized these natural mineral pigments into submicron/nano particles. It is observed that they exhibit different characteristics and unique colors when compared to natural mineral pigments sold in the commercial market. We could consider the possibility of applying the use these finely pulverized natural mineral pigments to various disciplines of the Arts. Here, we will discuss the present state of mineral pigments and the research conducted on natural mineral pigments by Joshibi University of Art and Design.
In this study, we have performed 3D DEM simulations about granular packings with slow tilt motion. It would be expected to obtain more detailed destabilization processes of tilting granular layers using numerical simulations than using experimental methods. Our simulation results agreed well with some experimental results about rearrangements of the particles at the surface layer. Most of the previous studies relate stability of the packings with mobilization of friction forces between the particles. However our simulation results show that the mobilization of friction forces does not change when the tilt angle increases up to 10° and further, the correlation between the mobilization of friction forces and global stability is insignificant. However, the direction of contacts and distribution of contact forces changed during our simulation time. Our simulation results indicate that we can estimate stability of the packings through contact forces and their directions rather than the mobilization of friction forces.
Dust collectors with bag filters are widely used to remove hazardous aerosols in work environments. Package type dust collectors, which include a fan and motor, differ in a wide variety of ways, such as the inner structure, the filter media, methods for cleaning collected dust, and flow control methods. In this study we focus on the performance of dust collectors for respirable dust fraction, which can reach the lung alveoli and cause pneumoconiosis. We surveyed the actual situation of dust collectors at worksites by means of light scattering photometers with PM2.5 cyclones, measured the details of performance of a typical dust collector using common test dust (Atomite) in a laboratory, and then tested the collection efficiency of the filter samples with and without dust load. The test aerosols for the filter samples were generated by the nebulization of standard monodisperse particles (Polystyrene latex particles, 0.6 to 3 μm). The penetration measured by photometers with PM2.5 cyclones approximated the performance of dust of 1.2 μm in nominal size. We propose the test methods at worksites and the filter media of bag filters in confirming the performance of dust collectors.
Particle size of raw materials is one of the most important factors in granulation, a general particle processing method. Especially in the case of granulation of multiple materials, component uniformity depends on the particle size. Therefore, pulverizing raw materials to a smaller particle size before granulation is often selected as a preprocessing method. Currently, there is a direct granule producing apparatus, which produces granules direct from a suspension of raw materials. The granules produced from this apparatus have unique features such as content uniformity, spherical shape, and high content yield due to less addition of excipients. From these features, the granules have advantages-such as ease to swallow and downsizing of final dosage form if they used for drugs. Here, we describe the necessity of raw material pulverization by confirming the correlation between particle size of the pulverized raw material and component uniformity of the granules produced by direct granule producing apparatus.
This article provides a brief overview of liquid-liquid phase separation fundamentals. First we discuss thermodynamic factors that drive spontaneous phase separation from homogeneous binary liquid mixtures. Next we introduce some mathematical models for chemical potentials in non-equilibrium state and intermolecular frictions to derive the governing equation for phase separations. Following classical Cahn-Hilliard theory, we show how the linear stability analysis gives the critical wavelength, at which the growth rate of concentration fluctuation shows a maximum. Finally, we discuss possibilities to utilize phase separation structures as a template to assemble/deposit/stratify solid particles on a solid surface.
Because of thermal stability, tunable porosity and modifiable surface, mesoporous silica is a promising material in catalysis, drag delivery and environmental applications. These industrial potentials could be enhanced by compounding mesoporous silica with Fe3O4 nano-particles, since its para-magnetism brings about the spatial mobility controlled under magnetic field. For the present research work, tetraethylorthosilicate was hydrolyzed and poly-condensed over the self-assembled surfactant micelles in the presence of Fe3O4 nano-particles in order to embed it in mesoporous silica SBA-15. Under the acidic condition caused by an aqueous solution of FeCl3, the poly-condensates were formed into the well-ordered hexagonal arrays of one-dimensional channels without dissolution of Fe3O4 nano-particles. This was the first successful synthesis of SBA-15 in which Fe3O4 nano-particles were embedded. On the other hands, another approach where SBA-15 was synthesized over Fe3O4 coated with amorphous silica in HCl aqueous solution ended in failure because the coated silica could not prevent Fe3O4 from dissolving in HCl aqueous solution. For the SBA-15/Fe3O4 composite prepared successfully, a quaternary alkyl-ammonium salt was grafted in order to prove the catalytic application.
A scale-up method of a low drug content mixing process in a V-type blender was proposed. Acetaminophen was used for the model drug, and the low drug mixing experiment was conducted using three scales of V-type blenders under the same fill level and Froude (Fr) number. However, the uniformity of mixtures could not correspond with the mixing time or the total revolution number. To find the optimum scale-up factor, discrete element method (DEM) simulations of three different scales of V-type blender mixing were conducted, and the total travel distance of particles under the different scales was calculated. The uniformity of drug content obtained from the scale-up experiments was well correlated with the mixing time determined by the total travel distance. It was found that the scale-up DEM simulation based on the travel distance of particle was valid for the low drug content mixing scale-up processes.
Plate penetration into dry granular materials is numerically studied using a large-scale discrete element method (DEM). To investigate the effects penetration angle on the interactions between particles and the plate, the simulations with the different angles from 0 (vertical penetration) to 60 degree are compared. The results show that the drag force acting on the plate increases with a decrease in the penetration angle. For all cases, the formation of shear bands from the plate tip to the free surface in the bed is confirmed. The analysis of energy consumption in the bed shows that most of the energy input to the bed by the plate is locally dissipated by sliding frictions between particles in shear bands. As the penetration angle decreases, the amount of energy dissipation due to the friction increases in the shear bands formed near the plate tip.