In this study, a numerical simulation model was developed in conjunction with X-ray CT (computed tomography) images of actual facemasks in order to clarify the behavior of submicron-sized particles in the facemask microstructure. It was found that the presence of large pores inside the microstructure caused streamlines to curve near the facemask domain, and particles accompanying the streamlines were more likely to be collected on the pore surface. Although the presence of pores results in a decrease in a pressure drop and the collection efficiency, the above effect suppresses the decrease in the collection efficiency and thus improves the performance (quality factor) of the facemask.

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We attempted to synthesize Zn_1–xMg_xO particles from a mixture of ZnO and MgO or Mg(OH)₂ particles using our original particle synthesis method, pulsed laser melting in liquid (PLML), and confirmed that an alloying reaction occurred. The solid solubility x of Mg in ZnO depends on the mixing method of ZnO and MgO or Mg(OH)₂ particles. The Zn_1–xMg_xO particles with solid solubility x = 0.09 and 0.20 were obtained from mixture particles prepared using mechanical mixing and coprecipitation methods. This is due to the smaller Mg(OH)₂ particles produced by the coprecipitation method and the higher frequency of contact between ZnO and Mg(OH)₂ compared to the mechanical mixing method. The solid solution limit of Mg to Wurtzite-type ZnO in this study was found to be between 0.20 and 0.24, which is comparable to the Mg solid solution limit of x = 0.2 reported for the conventional solid phase reaction of common ceramics.

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Dry powder inhalers (DPIs) require controlled aerodynamic diameters of 1 to 6 μm in order for the powder particles to deliver to the deep lungs. However, single-micron particles are difficult to release from inhalers due to their high degree of adhesion and aggregation. In addition, conventional DPI preparation methods cannot be applied to heat-sensitive drugs because they require processing at high temperatures. In this study, we focused on the electrospun technique. The applicant showed that cryo-milled polyvinyl alcohol nanofiber mats loaded with α-chymotrypsin (α-Chy) by electrospinning exhibited suitable inhalation properties for use in DPIs, while maintaining enzymatic activity. Porous particles with geometric diameters ranging from 10 to 35 μm were prepared to reduce adhesion. The in vitro aerosol performance of the milled nanofiber mats using a cascade impactor showed that the aerodynamic particle size was smaller (5.9 μm) than the geometric diameter, making the aerodynamic diameter suitable for DPI. The milled nanofiber mats maintained the enzymatic activity of α-Chy. Furthermore, the activity of milled fiber mats that had been stored for 6 months was comparable to the activity of those that were freshly prepared.

Scanning electron micrographs of the electrospun nanofiber mats and milled nanofiber mats. (a) A polyvinyl alcohol (PVA) nanofiber mat prepared using the electrospinning technique. (b) A PVA nanofiber mat milled by cryo-milling (freezing: 30 min, milling: 3 min).

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Perovskite quantum dots have excellent luminescence properties and are expected to be used as phosphors for wide color gamut displays. However, the development of an industrially practical synthesis method for quantum dots remains challenges. Although a proven pulverization method is promising for the synthesis of fine particles, it is difficult to achieve monodispersion of quantum dots due to aggregation and fusion of particles during the pulverization process. In this study, we apply the “ultrasound bead milling method,” which is a combination of “ultrasound” and “bead milling” originally devised by the authors. Ultrasound irradiation suppresses aggregation and fusion of the particles, allowing the particles to be milled while maintaining their dispersed state. This enables the synthesis of size monodisperse perovskite quantum dots, which can be further developed into light-emitting devices. In this study, the high superiority of the ultrasound bead milling was clarified by improving optical properties by evaluating the milling conditions, clarifying the milling mechanism through simulation, and fabricating and evaluating luminescent devices in a consistent manner.

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The mechanical reliability of products must be assured for scaling up and production of complex-shaped components by spark plasma sintering (SPS) of spray-dried granules. The evolution of morphologies of pores and defects, which control the mechanical strength, is investigated by using synchrotron X-ray multiscale tomography during SPS of alumina granules at 1300°C. While large defects arising from the hierarchical granule packing structure cannot be removed by pressureless sintering, crack-like defects and branched rodlike defects are almost eliminated by SPS at stresses higher than 30 and 50 MPa, respectively. But, small ellipsoidal porous regions, which may arise from aggregates or dimples of granules, cannot be removed even at a pressure of 50 MPa. A very large defect is also found by using micro-CT. It is supposed that this defect is formed from a large void in loosely packed granules. The shrinkage of large voids and the elimination of crack-like defects are explained by the theoretical prediction based on the continuum theory of sintering.

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All-solid-state lithium-ion batteries are promising next-generation secondary batteries, primarily because of their superior safety. In their production process, it is necessary to achieve large contact interfaces between the particles and improve particle fluidity. The particle shape of the solid electrolyte plays a key role in addressing these requirements. Li₃PS₄ (LPS) is synthesized in the liquid phase and offers the advantages of cost-effectiveness and production scalability. However, the mechanisms controlling particle size and shape have not yet been revealed. In this study, we synthesized LPS particles in the liquid phase using a hot stirrer and an ultrasonic homogenizer to investigate the effects of reaction temperature and impact force on the reaction time and particle shape. We successfully synthesized shape-controlled particles with high ionic conductivity by combining different synthesis methods. This study provides valuable data for optimizing the synthesis conditions to attain specific particle shapes and sizes.

SEM images of LPS synthesized by combinations of (a) hot stirrer and liquid-phase shaking method and (b) hot stirring and an ultrasonic homogenizer.

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mRNA-encapsulated lipid nanoparticles (mRNA-LNPs) are a crucial technology for mRNA medicine and have already been utilized in mRNA vaccines. The application of mRNA-LNPs in inhalation formulations is a promising strategy for developing effective respiratory infection vaccines. Therefore, this study aimed to develop a powder inhalation formulation of mRNA-LNPs. The powder formulation was prepared using the spray-freeze-dry (SFD) method. Its powder properties and function in cultured cells were evaluated, and a powder suitable for inhalation formulation was obtained while maintaining its function to some extent. However, it was suggested that mRNA leaked from LNPs due to ice crystals during freezing, resulting in functional degradation. Therefore, it is expected that technology will be developed to formulate mRNA-LNPs in powder form while maintaining their structure.

Schematic illustration of the preparation of powdered mRNA-LNPs.

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Spatial charge separation and extending light absorption capacity upto near-infrared regions are critical strategies for achieving highly efficient photocatalysis on the surface of semiconductive material. In this study, we realized the simultaneous reduction of WO₃ nanoparticle surfaces and heterojunction formation by combining carbon via an in-situ 2.45 GHz microwave plasma-assisted reaction, from a mixture of tungsten oxide particles and polystyrene as a carbon source. The WO_2.72/carbon composite particles exhibited broad light absorption capacity in the range of 300–800 nm and higher electrical properties compared with the raw WO₃ (about 75% lower charge transfer resistance, seven times longer electron lifetime, two times larger electron transfer number and effective reaction area). Moreover, in the photocatalytic degradation of rhodamine B under near-infrared irradiation (>750 nm), the composite particles performed an excellent reaction rate up to 6.6 × 10^–3 min^–1, which was 40 times higher than the activity of plasma-treated WO₃ without PS. Furthermore, it was proved that forming WO_2.72 and heterojunction with carbon enhanced the photocurrent value by more than two orders of magnitude and resulted in a nine times faster electron transfer rate upon photoirradiation.

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In manufacturing processes using slurries, particle dispersion control is important for optimizing product properties. However, the preparation of slurries is not easy due to the various parameters involved in dispersion control. In this study, we tried to clarify the effect of kneading process (In this study, kneading process is defined as a method of preparing a slurry by kneading at a high particle concentration and then diluting.) conditions on the dispersion state of particles, especially on their homogeneity, to provide a guideline for dispersion control. Slurries consisting of two types of particles, large and small, were prepared. The key parameter in slurry preparation was the particle concentration during the kneading process. We evaluated the slurries by measuring both flow characteristics and particle size distribution. As a result, particle dispersion was promoted, and the distribution became sharper as the particle concentration increased during kneading process. However, the effectiveness diminished when the concentration exceeded a certain threshold. These results suggest that a homogeneous dispersion can be created by adjusting the particle concentration during kneading process.

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During ball milling, particles sometimes strongly adhere to the surface of grinding balls and the grinding chamber, and this adhesion phenomenon is called sticking. The elucidation of the sticking mechanisms has been one of the most important issues to realize the control of the grinding behavior during ball milling. However, the sticking mechanisms have not been elucidated because particle sticking behavior has difficulty in being analyzed experimentally. Although the simulation techniques have been utilized to analyze such the particle behavior, the particle sticking behavior has not been analyzed because there is no simulation model to represent the motion, breakage, and adhesion of particles. Therefore, in this project, we developed a new simulation model for representing the motion, breakage, and adhesion of particles.

Comparison of particle behavior with and without adhesion when a grinding ball collides.

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The purpose of this study was to clarify the characteristics of acoustic streaming and particle motion with ultrasonic vibration in a closed field. Additionally, the aim also includes an investigation on flow transformation in the flow field. As a result, in the closed field, the number of vortices of acoustic streaming was changed by the Reynolds number. In flow field, the flow did not change when the flow velocity is 1 m/s, even though the vibration amplitude was set at 8 μm. But at the flow velocity 0.15 m/s, the flow changed like a sinusoidal wave. This means that the flow can be controlled by changing the flow velocity or vibration condition. As a result of the simulation, particles with a diameter of 1 μm were moved by acoustic streaming. On the other hand, particles with a diameter of 20 μm were moved to the antinode of acoustic pressure by acoustic radiation force. This means that the factors that dominate particle motion depend on particle diameter.

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Since the mean secondary flow in square duct turbulence involves heat and mass transport in the cross-section, its control has potential applications in high-efficiency heat exchangers, continuous chemical reactions in ducts, and particle separation. It has been known that heating the lower wall of a duct at low Reynolds numbers, where inertial and buoyancy forces are comparable, can significantly change the pattern of mean secondary flow; however, the control methods have not been discussed. In this study, numerical simulations of heating control of the lower wall surface of a duct channel were performed systematically to identify the range in which the secondary flow in the channel can be significantly controlled. Furthermore, an active heating control method using reinforcement learning was developed, showing that the secondary flow can be controlled more stably. In order to apply this flow control technique to a particle separation system, direct numerical simulations were performed to analyze particle dynamics in ducted turbulent flow. These results are expected to be applied to continuous chemical reactions and particle separation devices using rectangular flow channels.

The effect of gravity on the preferential location of particles.

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In order to manifest specific functionalities such as thermal insulation and light scattering in nanoparticle/polymer composite films, it is essential not only to design particles tailored to these functions and achieve dispersion at the nanoscale but also to emphasize the molecular-level integration at the particle/polymer interface. As polymer characteristics and curing methods diversify according to the application, we have proposed an evaluation method to understand the properties of both particles and polymers. Time-domain nuclear magnetic resonance (TD-NMR) can represent the physical properties of the surface of dispersed bodies in liquid through relaxation times. We present a report analyzing the changes in relaxation times obtained, along with a versatile evaluation method.

Change in the relaxation time (T₂) as a function of CNF concentration.

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Multi-nuclear metal complexes containing multiple metal ions and their bridging elements are recognized as nanoscale inorganic materials, and their synthesis and application as catalysts and materials have been extensively investigated. Among the multi-nuclear metal complexes, oxo-bridged iron complexes have attracted much attention because of their unique physical and chemical characteristics such as their catalytic performance and magnetic properties. In this research, we discovered the photocatalytic performance of the conversion of carboxylic acids under visible light irradiation, in which multi-nuclear iron complexes are formed upon reaction with carboxylic acids and photoreduction of the trivalent iron center proceeds by dissociating the carboxylate ligands around the iron center. In this photocatalytic reaction, carboxylate radicals are generated after photoirradiation, and subsequent decarboxylation forms organic radicals in the reaction mixture. Subsequent radical addition to unsaturated organic compounds affords the decarboxylative functionalization products.

Reaction set-up for photo-catalytic decarboxylative alkylation of carboxylic acids with electron-deficient alkenes.

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The properties of inorganic nanoparticles (NPs) are controlled by their size. Therefore, controlling the size of NPs is a fundamental technique in nanoscience. However, the size-tunable synthesis of inorganic NPs is generally carried out in a dilute solution, which produces a large amount of waste. Previously, we have reported the solvent-less synthesis of inorganic nanoparticles via thermal decomposition of an alkylamine-coordinated metal oxalate complex. As a result, the waste produced after the synthesis of nanoparticles drastically decreased. In addition, the size of inorganic nanoparticles can be predictably controlled via stepwise thermal decomposition of metal oxalate. However, species of alkylamine coordinated metal oxalate complex are few (Fe, Cu, and Ag). Here, a new type of alkylamine coordinated metal oxalate complexes was synthesized using other metal ions. The properties of the synthesized alkylamine coordinated metal oxalate complexes were measured using X-ray diffraction, Fourier transform infrared spectrum, thermogravimetric analysis, and other techniques.

The formation of alkylamine-coordinated oxalate complex via mixing oxalate complex and alkylamine.

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In order to realize a biorefinery society, it is necessary to convert cellulose, which has a crystalline structure and is difficult to decompose, into glucose, which is the starting point for producing useful substances. However, this strategy requires a large amount of energy to be invested because materials are difficult to decompose. Therefore, it is nonsense to invest energy in order to produce energy. It is necessary to consider methods with a low load. In this research, we will reflect a unique enzyme clustering design on the surface of star-shaped gold nanoparticles, which have the property of converting sunlight (natural light) into heat. By immobilizing heat-stable cellulase, we have developed a method to improve the local temperature of only the enzyme-reaction field in a photoresponsive manner and improve the efficiency of enzymatic saccharification without using a boiler.

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Polymer coating on ceramic particles contributes to the homogeneity and high dispersion of powders and improves their properties. The current polymer coating technology can control the structure and composition, but the process is complicated. Therefore, we have developed a technique for selective polymer formation on the surface of particles using radicals at the extreme surface of particles induced by mechanical treatment that does not destroy the particles or increase the temperature. In this study, polystyrene was coated by the reaction of surface radicals with styrene using silica particles as a model material. The processing time, the amount of styrene added, and the material of the base particles were varied as parameters, and the formation mechanism of polystyrene was investigated. Based on these results, we will continue our research to elucidate the formation mechanism of polymers by ball milling.

TEM and SEM images of prepared particle.

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Scaffolds that reproduce the extracellular matrix (ECM) of tissues and organs are necessary for tissue regeneration and analysis of cell function. Decellularized tissue, which is obtained by removing immunogenic cells from human or animal tissue, is used as a transplant material, but it is difficult to use as a scaffold for cell culture because cells do not infiltrate. In this study, we developed a method for fabricating an ECM block by pressure molding, and worked on making the ECM block porous and elucidating its usefulness as a cell culture substrate. It was found that a high-strength ECM block can be fabricated by applying cold isostatic pressure (CIP), and that the properties of the ECM block change depending on the raw material of the decellularized tissue powder. Furthermore, the blocks were made porous using NaCl and protein cross-linking enzymes, and cells were shown to be able to adhere to the porous ECM blocks. This study established the basis for creating new scaffold materials containing the ECM composition of animal tissues using CIP molding.

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In this study, the author aimed to develop a preparation technique for poly(lactic-co-glycolic acid) (PLGA) nanoparticles. By incorporating a unique suction actuator into a polydimethylsiloxane (PDMS) pumpless microfluidic chip, the author successfully controlled high-viscosity polymer solutions, achieving the effective generation of PLGA nanoparticles. It was suggested that polyvinyl alcohol (PVA) dissolved in the aqueous phase as the continuous phase played a key role in the stable formation of oil-in-water droplets. Within the droplet collection reservoir of the microfluidic chip, the crystallization process of PLGA based on the mutual dissolution of the oil and water phases was observed. The vacuum-packed, degassed PDMS microfluidic chip demonstrated long-term preservation without compromising performance, supporting the implication that the timely preparation of PLGA nanoparticles is feasible through this method. This study highlights the success of this novel approach in the controlled production of PLGA nanoparticles, emphasizing its potential for practical applications.

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Ash particle adhesion at high temperatures is a serious problem in commercial combustion plants. Melting of compounds containing alkali metals is one of the causes of particle adhesion at high temperatures. In this study, an additive has been developed to control ash adhesion at high temperatures. An Al-based additive has been used to suppress the formation of compounds with low melting points in ashes. Furthermore, it has been expected that gases released from the additive during elevating temperatures can form voids in the ash powder bed, resulting in a decrease in the tensile strength of the powder bed. It has been found that the use of aluminum sulfate as an additive effectively decreased adhesion through composition control and void formation.

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Geopolymers using coal fly ash, an industrial byproduct from coal-fired power plants, have the ability to immobilize heavy metals during the curing process, and are expected to be used in the field of environmental remediation. The low reactivity of coal fly ash and the long curing time required for curing are practical issues. In this study, geopolymers were prepared by the mechanical treatment of coal fly ash particles under relaxed curing conditions, and the effect of the mechanical treatment on the Pb²⁺ immobilization ability of coal fly ash was investigated. The mechanically treated coal fly ashes were subjected to the mechanical treatment, and the increase in specific surface area and the decrease in crystallinity promoted the leachability of Al³⁺ and Si⁴⁺ ions, which are necessary for hardening of the geopolymer. As a result, the geopolymer could be cured at room temperature and in a short time, and the room temperature curing showed the same high Pb²⁺ immobilization capacity as that of the heat curing. It is suggested that the mechanical treatment of coal fly ash particles contributes not only to the curing reactivity of the geopolymer but also to its heavy metal immobilization ability.

SEM images and specific surface area of coal fly ash milled by various comminution time.

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Highly crystalline perovskite-type oxynitride BaTaO₂N was prepared by using low-temperature melting BaCN₂ flux and Ta₂O₅. The Ba-rich starting composition of the BaCN₂/Ta₂O₅ mixture was required to synthesize the single phase of BaTaO₂N powders, because of evaporation of a small part of BaCN₂ during the heating in N₂ atmosphere. The crystallite size of the BaTaO₂N obtained from BaCN₂/Ta₂O₅ was 100 nm, which was larger than that obtained by ammonolysis reaction. Truncated octahedral particles consisting of (111) and (100) planes were obtained in the products. By using the BaCN₂ flux, highly crystalline BaTaO₂N fine particles were obtained.

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Polymer particles are materials applied in diverse fields such as coatings, electronics, and medical components. Generally, polymer particles form a spherical shape because of their low surface free energy. In this study, we show that dodecyl acrylamide polymer (pDDA), which forms a lamellar structure by “nano-phase separation” of the main and side chains under humidification, undergoes a self-organized structural change from a fine particle shape to a plate shape. Nanoparticles of pDDA prepared by the flash nanoprecipitation method have a spherical shape of about 50 nm. When the nanoparticles were annealed under humidified conditions we found that the spherical structure changed to a plate-like structure. This is thought to be due to the fact that the polymer chains that formed random chains in the nanoparticle state were stacked into lamellae by humidified annealing. In other words, we succeeded in changing the macrostructure of the particles by changing the conformation of their component polymer.

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The discrete element method (DEM) is a promising method for solving various problems on powders. However, there are a number of input parameters for DEM simulations. This study demonstrates the inverse prediction of the DEM input parameters from the DEM output powder properties using machine learning techniques. The simplest powder model, a non-adhesive powder, was used as the powder. Outflow rate, aerated bulk density, and repose angle are adapted as powder properties. A database for machine learning was constructed by performing DEM simulations on the powder properties with 750 combinations of input parameters consisting of friction coefficient, restitution coefficient, spring constant and shape parameter. Support vector (SV) regression successfully reproduces the DEM input parameters from the DEM output powder properties with practical accuracy. These results lead to further use of machine learning in DEM simulations.

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Core–shell polymer particles, which exhibit multiple distinct physical properties, are utilized in a variety of products, including optical materials, diagnostics, and fillers. These particles are fabricated through a multistage process that begins with the preparation of seed particles and is followed by the polymerization of shell materials. However, this method is time-consuming and involves complex procedures. In this study, we have developed a continuous microflow process using slug flow to produce core–shell polymer particles. This report introduces a rapid technique to synthesize monodisperse core–shell polymer particles through sequential soap-free emulsion polymerization within a Water-in-Oil slug flow.

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Thin films of Fe₃O₄ were prepared by transferring Langmuir films of Fe₃O₄ nanoparticles (NPs) coated with oleic acid molecules at air–aqueous interfaces. The packing of the NPs in the film was controlled via the concentration of NPs in the spreading solution used to form the Langmuir film. Films resembling a network of thin wires were obtained when a low NP concentration was used. In contrast, films of wires of irregular shapes and thicknesses were obtained when spreading solutions with high NP concentrations were used. The irregular NP packing observed at high NP concentrations is explained by NP aggregation at the air–aqueous interface. This aggregation is explained by inter-particle hydrophobic forces due to the oleic acid molecules adsorbed onto the NPs. The NP aggregation in the films was further reduced by adding charged SiO₂ NPs to the Fe₃O₄ NP films. The SiO₂ NPs introduced electrostatic repulsions in the films, which reduced the NP aggregation. The ability to form thin films showing a controlled NP packing without aggregations is envisioned to improve their ability to be used in nano- and bio-technological applications.

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Several types of metal–organic frameworks (MOFs) exhibit S-shaped adsorption isotherms due to their structural expansions. These materials are obtained as powder samples and require molding for industrial use; however, molding the samples with polymer binders reportedly made the S-shape less distinct. Our previous study elucidated this mechanism: the polymers inhibited the volume expansion of MOFs in the pellets. In this study, we molded two types of flexible MOFs exhibiting different volume expansion ratios and compared their adsorption behaviors. We concluded that a flexible MOF with a smaller volume expansion suppresses the smeared effect when in pellet form.

Mechanism of the first and second CO₂ adsorption/desorption cycles on MOFs with different volume expansion ratios.

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We have proposed a hot-melt kneading process using sulfur and porous carbon to produce composite cathodes for all-solid-state batteries. In this study, we investigated a key parameter to control the structure of composite particles obtained from the hot-melt kneading process. Furthermore, we investigated the correlation between composite-particles structure and their electrochemical performance. By changing the weight ratio of sulfur to porous carbon, the two types of composite particles were produced: composite particles with almost all sulfur existing inside the pore; and those with a part of sulfur existing outside the pore. The latter composite particles exhibited higher cycle performance.

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Block copolymers (BCPs) form lamellar, sphere, and cylinder structures via microphase separation between each block. Our motivation is the synthesis of a block copolymer composed only of catechol derivatives. Thus, in this study, we report a synthesis of poly (dopamine acrylamide) (pDOPAm) via controlled reversible addition–fragmentation chain transfer (RAFT) polymerization of DOPAm without a protective group using DMF as the solvent. Furthermore, we synthesized the block copolymer consisting solely of catechol derivatives.

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Drug-loading to MOFs (Metal-organic-frameworks) is generally conducted in liquid-phase adsorption. However, the relationship between MOF–drug–solvent interactions and drug-loading capacity has not been fully investigated. This study experimentally and numerically investigated the mechanism of drug encapsulation in MOF pores, focusing on solvents and functional groups of MOFs. Experimentally, it was revealed that the polarities of solvents and the electron-donating/withdrawing property of MOF ligands were essential factors for the drug-loading capacity. Furthermore, molecular simulations suggested that the balance of MOF–drug–solvent affinity contributed significantly to the drug-loading mechanism.

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The calculation methods of Discrete Element Method (DEM) for wet powder flow are diverse, and lacking a unified assessment. In this study, four calculation methods, combining two approaches for bridge formation distance and liquid bridge force during particle contact, were applied to a rotating drum mixer. Comparisons of the results revealed the significant impact of calculation methods for wet powder on the outcomes. Moreover, comparison with experimental data revealed that the Liquid Film Contact model (LFC) demonstrated the ability to accurately represent experimental results even under high liquid content.

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In wet forming of ceramics, cracking and deformation of the slurry during the drying process are critical issues. In this study, a technique for understanding drying behavior was developed by observing the internal structural changes of the slurry during the drying process using OCT, which can observe the inside of opaque objects, and by measuring the mechanical properties of the dried body using a nanoindentater, which can measure the microscopic mechanical properties. It was found that the mechanical properties of the dried body depended on the internal structural changes during the drying process caused by the type of binder added.

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A hybrid catalyst composed of naturally occurring metal complexes and semiconductor photocatalysts enables a variety of molecular transformations in a green and sustainable manner. In this study, we have developed the visible light-driven hybrid catalyst (B₁₂–Mⁿ⁺/TiO₂) composed of “vitamin B₁₂” and “metal ion-grafted TiO₂ (Mⁿ⁺/TiO₂)”. The B₁₂–Mⁿ⁺/TiO₂ was prepared by mixing of B₁₂ derivatives and Mⁿ⁺/TiO₂, and this hybrid catalyst was thoroughly characterized by various measurements. The B₁₂–Mⁿ⁺/TiO₂ effectively produced reactive Co(I) species under visible light irradiation. In addition, the reactivity of Co(I) species toward CO₂ reduction was investigated in this study.

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For the fabrication of complex-shaped porous SiO₂ components with higher porosity, an interparticle photo-cross-linkable w/o Pickering emulsion suspension with low particle concentration was designed using nanoparticles. The designed suspension was photocured in a silicone mold with a complex structure. By firing the green compacts at 1000°C, a slight neck growth between the raw SiO₂ nanoparticles progressed while maintaining the pore structure generated by the dispersed aqueous phase. In addition, the complex-structured porous SiO₂ parts with higher porosity compared to conventional systems using submicron particles were successfully obtained by rapid heating process without occurring any structural collapse.

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Porous structures are increasingly getting attentions in developing environmental catalysts, such as three-way catalysts (TWC), due to their ability to improve catalyst performance without changing their composition. This study explored various template-to-TWC mass ratios to create an optimal interconnected nanoporous structure while maintaining the catalyst morphology. This optimized sample was then investigated to compare CO oxidation performance with nanoparticles and aggregate structures. The results demonstrated that the nanoporous structure improved CO oxidation efficiency by 50% compared with other structures. This improvement is attributed to the better diffusion of reactants within the interconnected porous structures of the nanoporous sample. These findings highlight the critical role of nanoporous structures in enhancing the effectiveness of environmental catalysts.

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Digital and electrical technologies are vital to achieve global sustainable development goals (SDGs). These devices and machines require high-performance powder magnetic core inductors. This study successfully enhanced the magnetic characteristics of this component by incorporating submicron-sized silica-coated FeNi (FeNi@SiO₂) particles. The Swirler-assisted spray pyrolysis method was used to achieve an efficient one-step synthesis of FeNi@SiO₂ particles. To obtain particles with high-quality coating, the effect of an additional gas flow rate (Q_a) for providing swirling flow to disperse FeNi aerosol and HMDSO vapor was investigated. The optimum Q_a resulted in FeNi@SiO₂ particles with 353 nm diameter, 25 nm shell thickness, a high coating ratio (96%), and low free SiO₂ nanoparticle impurity.

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