In this study, we propose a non-destructive method combining optical microscopy images and convolutional neural networks (CNNs) to estimate component mixing ratios in pharmaceutical powder blends. Two CNN architectures, VGG16 and Xception, were trained as regression models on binary mixtures (CEOLUS PH-101 and PEARLITOL 200SD) and ternary mixtures (Ibuprofen, Pharmatose 100M, and CEOLUS UF-702). The Xception model achieved high predictive accuracy, with a coefficient of determination of 0.821 for the binary mixture and 0.935 for the ternary mixture, along with a low Root Mean Square Error of Prediction (RMSEP) and a low Mean Absolute Error (MAE). Feature representations from the intermediate CNN layers were visualized using UMAP (uniform manifold approximation and projection), revealing distinct clustering according to mixing ratios, indicating that the model effectively captured subtle morphological differences in particle structure. This approach offers a promising tool for real-time, non-destructive quality control in pharmaceutical manufacturing, potentially reducing reliance on sampling-based or chemical analytical methods.
This study proposes a novel, non-destructive method for estimating excipient mixing ratios in pharmaceutical powders by combining optical microscopy imaging with deep learning. The approach enables AI to extract subtle particle features beyond human visual perception, achieving high-accuracy quantitative evaluation with clear feature separation. Because the method is implementable with standard imaging equipment, it holds strong potential for real-time quality assurance and process analytics in pharmaceutical manufacturing.
This study proposes a simple gas-phase coating technique for synthesizing core–shell particles with metallic cores via a one-step aerosol process based on the control of gas–liquid–solid interfaces. By adjusting the precursor concentration and hydrogen gas flow rate, the particle morphology, size, and crystal structure could be precisely tuned. During synthesis, the balance among the formation and reduction behaviors of Fe, FeO, and SiO2 phases was optimized to achieve the formation of a stable silica shell. As the precursor concentration increased, the core size increased while the SiO2 shell became thinner, in good agreement with the predicted trend. Powder X-ray diffraction analysis revealed that a sufficient hydrogen supply is essential to suppress the formation of oxide impurities and to achieve complete reduction to metallic iron. The obtained core–shell particles exhibited a uniform spherical morphology and well-defined core–shell structures, demonstrating the effectiveness of interface control in gas-phase synthesis.
This study proposes a one-step aerosol process for synthesizing Fe@SiO₂ core–shell particles with metallic iron cores, based on the control of gas–liquid–solid interfaces. Tuning the precursor concentration enables control over both particle diameter (475–710 nm) and silica shell thickness (29–13 nm), and the molar ratio of hydrogen to precursor is shown to be critical for achieving complete reduction to metallic iron. The synthesized particles are expected to find promising applications in the field of magnetic materials.
In this study, the feasibility of a CO2 separation process based on ion-induced nucleation was investigated. Ion-induced nucleation is a heterogeneous nucleation process in which gas-phase molecules aggregate around an ion, allowing cluster formation under milder supersaturation conditions compared to homogeneous nucleation. First, the adsorption–desorption dynamics of vapor molecules on an ion surface were modeled using queueing theory, and the theoretical predictions were compared with molecular dynamics (MD) simulation results. The arrival-interval and binding-time distributions obtained from MD simulations showed good agreement with exponential distributions under low vapor pressure conditions. Next, ion-induced nucleation of CO2 was investigated using MD simulations of CO2–N2 gas mixtures containing a single ammonium ion, representing the dilute ion limit. Under conditions where homogeneous nucleation was suppressed, the formation and growth of CO2 nanoclusters around the ion were clearly observed. These results demonstrate that ion-induced nucleation can effectively lower the nucleation barrier and promote particle formation. The findings of this study suggest the potential of combining ion-induced nucleation with sonic nozzle separation to realize a low-energy and efficient CO2 separation process.
This study focuses on ion-induced nucleation, in which gas-phase molecules accumulate around an ionic core, and examines its fundamental processes using a stochastic model (queuing theory) and molecular dynamics simulations. By analyzing adsorption–desorption dynamics and early-stage cluster formation around a single ion at the molecular level, the study demonstrates that ions can serve as effective nucleation sites for molecular accumulation in the gas phase. The findings provide fundamental insights relevant to the future design of gas-component separation and purification processes.
This study aimed to clarify the effects of nanoplastics on microorganisms in aquatic environments and establish guidelines for controlling their toxicity. Positively charged polystyrene nanoparticles were used as model nanoplastics, and Escherichia coli at different growth stages (exponential and stationary phases) were employed as model microorganisms. Particle exposure experiments were conducted under various salt concentrations. Bacterial size, particle adhesion, cell membrane integrity, and colony-forming ability were evaluated using flow cytometry (FCM) and confocal laser scanning microscopy (CLSM). The results showed that under low-salinity conditions, nanoparticle adhesion increased, leading to significant cell membrane damage and reduced colony-forming ability. In contrast, under high-salinity conditions, particle adhesion and cytotoxicity were suppressed due to electrostatic screening effects. Cytotoxic effects caused by particle adhesion were more pronounced in exponentially growing cells than in stationary-phase cells. These findings demonstrate that not only exposure conditions but also the microbial growth state strongly influence the toxicity of nanoplastics toward microorganisms.
This study systematically investigates the factors influencing nanoplastic adhesion and toxicity toward microorganisms in aquatic environments, examining not only exposure conditions (medium salinity) but also the growth state of the microorganisms (exponential and stationary phases). The results demonstrate that toxicity due to particle adhesion is pronounced in Escherichia coli during the exponential growth phase, whereas it is comparatively low during the stationary phase. These findings highlight the critical role of microbial growth state in governing nanoplastic toxicity.
Porous Al particles with etching pits on their surfaces were produced by anodic etching of Al particles placed inside a rotating barrel. In this method, electrical current flows through the Al particles as they contact a Pt plate at the bottom of the barrel, causing anodic etching of their surfaces. The structure of the etching pits formed on the Al particle surfaces could be controlled by varying the current and electrolysis time. Furthermore, using an electrolyte containing a surfactant prevented particle flotation and enabled the formation of etching pits on Al surfaces with particle sizes smaller than 5 μm. Porous Mg particles can also be produced by performing barrel anodic etching using Mg particles as the starting material. The porous particles obtained using this method are expected to have various applications, such as in sensors, catalyst supports, and batteries.
This study reports an efficient method for fabricating porous Al and Mg microparticles with well-defined surface structures. By employing an electrochemical process for pore formation, the pore depth can be precisely controlled by adjusting the applied charge. The porous microparticles produced by this method are expected to find broad applications in diverse fields, including sensors and batteries.
Overview of Recent Activities
Released on J-STAGE: May 31, 2024 | Volume 31 Pages 3-15
The 8th Asian Particle Technology Symposium APT2021
Released on J-STAGE: May 25, 2022 | Volume 29 Pages 128-131
Satoru WATANO
Environmentally friendly growth of functional nanocrystals with upconversion fluorescence
Released on J-STAGE: December 29, 2017 | Volume 17 Pages 61-66
Katsuya Teshima