In the production of pharmaceutical solid formulations such as tablet, the spherical crystallization method, in which crystallization and granulation are carried out simultaneously in the same system, can integrate the downstream in the pharmaceutical production process, thus enabling high efficiency in pharmaceutical manufacturing. On the other hand, process enhancement such as filtration, drying, and formulation after crystallization has been an issue. To solve this problem, we developed a one-pot processing system with hybridized powder processing operations in addition to filtration and drying functions. This desktop-sized device has a highly functional rotating spherical chamber that can handle all the processes of filtration, drying, powder mixing, and wet granulation at once. In this study, we confirmed that the suspension of fenofibrate granules prepared by the spherical crystallization method can be processed by the one-pot powder processing equipment. It was also found that the wet granulation of acetaminophen granules was possible by spraying binder from the spray nozzle in this apparatus.
It would be essential to make the manufacturing process as efficient as possible to achieve personalized manufacturing of pharmaceuticals in the future. We have developed a one-pot processing system that integrated powder processing operations in addition to filtration and drying. This table-top equipment was designed to perform the processes of filtration, drying, powder mixing, and wet granulation in a single operation.
In Discrete Element Method (DEM), it is common to reduce the particle stiffness artificially from the original material property to employ a large time step and reduce the computational cost. When simulating cohesive particles, however, the reduction of the particle stiffness can cause excessive energy dissipation due to the prolonged contact duration, which can make the particles become more cohesive than the original ones. Recently, several scaling laws for attraction force are proposed to overcome this problem. Although these scaling laws are effective for dynamic systems where particles are fully fluidized as a bulk body, they are not applicable to relatively static systems since the instantaneous force balance is not maintained. In the present work, a new approach to reduce the viscous damping coefficient instead of the attraction force is proposed. The proposed model is applied to simulate cohesive particles in a rotary drum, and it is confirmed that the static phenomena such as the particles sticking on the drum wall as well as the dynamic phenomena such as the dynamic angle of repose are well replicated at the same time, which is difficult to achieve with the conventional method.
In Discrete Element Method (DEM), it is common to reduce the particle stiffness artificially from the original material property to reduce the computational cost. When this method is applied to simulate cohesive particle flows, it is necessary to prevent the excessive energy dissipation caused by the prolonged contact duration, which can make the particles become more cohesive than the original ones. In this article, a new method to scale the viscous damping coefficient according to the reduction of the particle stiffness is proposed to replicate the both static and dynamic flows of the original cohesive particles at the same time.
Surface-enhanced Raman scattering (SERS) is a phenomenon in which Raman scattered light of molecules adsorbed on noble metal nanoparticles with a diameter of about 50 to 100 nm is greatly amplified by surface plasmon resonance on the metal surface. Since it is possible to detect trace components, it is expected to be applied to ultra-sensitive analysis in a wide range of fields such as the medical field and the biological field. In SERS, it is known that when particles form a dimer or a further aggregate, an extremely strong electromagnetic field called a hot spot is formed between these particles. Since the target molecule is selectively adsorbed between such particles, the SERS effect is expected to be further amplified in the aggregated particles due to the synergistic effect of these two. However, the relationship between the aggregation state of such particles and the surface enhancement effect has not been completely elucidated. In this study, we fabricated a nanoparticle multilayer film by atomizer and verified the SERS effect due to the aggregate structure of the particles. The SERS effect was obtained with the nanoparticle accumulated film that prepared by 70-nm Ag nanoparticles with colloid concentration of 4.3 × 1012 particles mL–1.
Surface-enhanced Raman scattering (SERS) is expected to be applied to ultra-sensitive analysis in a wide range of fields such as the medical field and the biological field. In SERS, it is known that aggregate structure is important to obtain high electromagnetic field. Since the target molecule is selectively adsorbed between primary particles, the SERS effect is expected to be further amplified in the aggregated particles due to the synergistic effect. In this study, we fabricated a nanoparticle multilayer film by aerosol technique, and obtained extremely high SERS effects.
This study was conducted to reveal the relationship between properties of porous membrane and process conditions, when membrane is manufactured via wetting process. Membrane in this study was manufactured using two kind of carbon black (XC-72r and Li-100) which have different specific surface area. Time of ultrasonic dispersion to disperse carbon black and heating temperature to evaporate medium were process conditions to be changed. The thickness, permeability and surface roughness were measured for obtained membrane. As a result, permeability increased to the thickness in the case used Li-100. On the contrast, it was almost constant to the thickness for the case of XC-72r. Although the surface roughness did not depend on the thickness obviously, it became larger for the membrane used the slurry of bi-modal particle distribution for carbon black than used the slurry mono-modal. Consequently, it was revealed that the tendency of permeability and surface roughness to the membrane was understood by the morphology and particle distribution in slurry of carbon black.
Control of properties of porous membrane consisting of carbon-black (CB) and ionomer was investigated, intending the catalyst layer in fuel cell. Slurry in which CB and ionomer were dispersed was coated on the substrate by doctor blading. Porous membrane was manufactured by drying its wetting film. As a result of the measurement of permeability of membrane, it was approximately constant when the specific surface ratio of CB is large, on the contrary, it increased with the membrane thickness when specific surface ratio is small.
Particle adhesion and deposition in dry powder processes can result in low quality and productivity. In this study, to establish a method for controlling the charge and motion of particles and for removing them without using fluid and/or mechanical external forces, dielectric particles deposited on an insulating plate were charged and levitated using ultraviolet (UV) irradiation in an upward electric field. The particles in the top layer irradiated by UV light were positively charged by photoemission and levitated by the Coulomb forces. The flux and motion of the levitated particles and the charge of each levitated particle were experimentally obtained. The results showed that approximately 40% of the levitated particles descended because of the change in particle charge due to negative charge clouds formed by the photoemission from the particle layers and the levitated particles. Furthermore, applying an upward electric field after UV irradiation, all the particles were levitated without descending because the negative charge clouds were not formed. In addition, more particles were levitated due to an increase in particle charge, but the continuous levitation did not occur.
The use of an electric field and ultraviolet enables to control of the charge and motion of particles n in the absence of complicated mechanical and/or pneumatic systems. This article describes a method to charge and levitate the dielectric particles deposited on the insulating plate by an upward electrostatic field and UV irradiation and the effect of photoelectrons emitted from the particles by UV irradiation on the flux and motion of the levitated particles.
Formation of Lipid Nanoparticles and Elucidation of Formation Mechanism
Released on J-STAGE: June 10, 2017 | Volume 24 Pages 74-78
Manabu TOKESHI
Development of DEM Model Considering Viscous Force due to Liquid Bridge
Released on J-STAGE: May 31, 2018 | Volume 25 Pages 138-143
Kimiaki WASHINO