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The anti-solvent crystallization behavior of the glycine aqueous and ethanol system was addressed through molecular dynamics simulation of a non-equilibrium state. A rectangular simulation cell was assigned to mimic the instant of the first contact state of the aqueous phase (solvent) and ethanol (anti-solvent). Here, glycine zwitterions began to aggregate into clusters with the invasion of ethanol into the aqueous phase, caused by the dehydration and supersaturation of the area. The number and size of clusters gradually increased with the formation and collapse of the clusters with time progression as liquid structures. The cluster structure reacted to the degree of supersaturation and exhibited higher probability of structured interaction modes, especially in ethanol rich areas. Pre-determination of the crystal polymorph during liquid–liquid phase separation was suggested for this water and ethanol anti-solvent system with the glycine zwitterion as the simplest amino acid, which contained multiple interaction sites. These findings agree with the experimental results and support the precursor behavior of nucleation and mechanism in the two-step nucleation theory and liquid–liquid phase separation.

Many oil-encapsulation techniques, in which particles are used to improve the stability of polyunsaturated fatty acids (PUFAs) against oxidation and the handling of oils, have been reported. We developed techniques for encapsulating oil within powders with a liquid–liquid interfacial crystallization by using nozzleless electrostatic atomization. This process was used to prepare fine spherical encapsulated soybean oil particles with a microscale single process. An inexpensive soybean oil containing PUFAs was chosen as the oil phase. W/O emulsion systems were synthesized via the electrostatic atomization process. After the W/O emulsions were prepared, glycine and taurine well provided in supplements were used as the wall material for encapsulation. The soybean oil content of the encapsulated particles and their stability at high temperatures were evaluated. The oxidative stability of the soybean oil during high-temperature storage was improved for the encapsulation.

The amorphization of indomethacin (IMC) with cystine (Cys2) was studied by discrete element method (DEM) simulations and principal component analysis (PCA). X-ray powder diffraction (XRPD) analysis suggested that the conversion of crystalline IMC to amorphous state was accelerated by co-grinding with Cys2. XRPD spectra about amorphization of IMC with Cys2 were analyzed by PCA. PCA results suggest that IMC/Cys2 system undergoes two-phase amorphization, as indicated by the 2nd PC score, and that the change in phase depends on the total frictional energy calculated by DEM simulations. Electron spin resonance result revealed that the radical from Cys2 may be related to the amorphized progression of IMC.

Liquid-liquid interfacial crystallization requires mutual diffusion between two liquids to drive the crystallization. Understanding mass transfer between two liquids is important for achieving sophisticated morphological control. In this work, the effect of mutual diffusion on crystal morphology was examined by calculating the solute concentration near the interface. NaCl crystals were prepared with various organic solvents. The crystal shape, amount of precipitation, and particle size were evaluated. The diffusion rate in each organic solvent was measured from the time evolution of the surface area and the volume of the droplet. The solute concentration and the supersaturation ratio near the interface were calculated by Fick's law. The change in crystal morphology revealed that either nucleation or crystal growth preferentially occurred depending on the organic solvent. The magnitude of the water diffusion rate affected the crystal morphology. The dependence of the crystal morphology on the organic solvent was also determined by the diffusion coefficient and the mutual solubility. These results provide new insight into our understanding of the mutual diffusion at liquid-liquid interfaces and the development of crystal morphology control.

Amorphization and radical formation from micro- and nano-sized particles of cystine in mechanochemical process were examined. Dry grinding was used to create amorphous cystine particles. Cystine samples after dry grinding were characterized using a scanning electron microscope, the Brunauer-Emmett-Teller method, powder X-ray diffraction, electron spin resonance (ESR), and Fourier transform infrared (FT-IR) spectroscopy. The kinetic characteristics of amorphization from nano-sized particles were assessed from the ball impact energy and force calculated using the distinct element method (DEM) simulations. The results showed that the kinetics of amorphization almost followed the Johnson–Mehl–Avrami equation using DEM simulations without adhesion. In addition, the amorphous progression exceeded the threshold value of the impact force. The radical species of cystine particles were identified by evaluating the substance-specific value from ESR spectra and the absorption intensity of FT-IR spectra. The results demonstrated that the radical produced by grinding was a thiyl radical (RS ) because the peaks at 452 cm − 1 in the spectra resulted from the characteristic absorption frequency of disulfide (S-S). The radical formation was closely related to the amorphization of cystine particles.

The purpose of this study was to produce composite particles, consisting of core starch particles coated with glycine, by liquid–liquid interfacial crystallization with an ultrasonic spray nozzle and to investigate the effect of operating conditions on glycine particle morphology. We confirmed that ultrasonic irradiation could improve the coating efficiency of the core starch particles during the crystallization process. We also investigated the transformation between different polymorphs of glycine crystals that covered the starch surface. The coating efficiency of the fine glycine crystals on the starch particles was improved by using an ultrasonic spray nozzle rather than anti-solvent crystallization without an ultrasonic spray nozzle. The glycine crystals on the surface of starch particles transformed from unstable to stable forms according to the solution-mediated mechanism and Ostwald rule of stages. The interaction between the core particles and guest particles was found to be a key factor in producing the composite particles. The results indicate that this crystallization process using the ultrasonic spray nozzle is promising for efficiently producing composite particles.

The aim of the present work is to apply the liquid–liquid interfacial crystallization using a piezoelectric inkjet nozzle to the sol–gel processing. The instillation process was compared with the batch process to elucidate the effectiveness of the inkjet technique on the liquid–liquid interfacial sol–gel processing. The effect of frequency and water concentration in titanium tetraisopoxide (TTIP) solution on titania particle properties was investigated for sol–gel processing with a piezoelectric inkjet nozzle. Titania particles produced by each process were calcined at 500 °C. The crystal structure, morphology, pore size distribution and specific surface area of titania particles were evaluated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen physisorption measurement. The photocatalytic activity of titania particles was evaluated by the photodegradation of methylene blue solution under UVC light irradiation. Monodispersed titania particles could be produced by instillation sol–gel processing of hexane using a piezoelectric inkjet nozzle. Titania particles prepared at 1500 Hz were spherical while titania particles prepared at 1000 Hz and 3000 Hz were non-spherical. The number of particulate fracture increased with water concentration in TTIP solution. The inkjet nozzle-mediated instillation processing was found to be a promising way to create porous titania particles with a high photocatalytic activity.

The aim of this study is to apply the inkjet technique to liquid–liquid interfacial crystallization. Instillation with an inkjet nozzle was compared with the batch process in order to evaluate the effectiveness of the inkjet technique for controlling particle morphology. The effects of amino acid solution concentration and organic solvent type on particle properties were investigated for instillation with an inkjet nozzle. The morphology of alanine and glycine particles was observed by scanning electron microscopy and X-ray powder diffraction. The inner structure of alanine and glycine particles was investigated by cutting particles with an ion milling machine. Controlling particle size by adjusting the droplet size in the instillation with an inkjet nozzle was found to be feasible. Most alanine and glycine particles produced by instillation were spherical, whereas most particles produced by the batch process were non-spherical. A higher concentration of amino acid in the solution may lead to the generation of solute particles at the spherical interface. It was found that the surface structure of alanine particles changed when using two kinds of organic solvents as anti-solvents. In addition, instillation allowed for β-glycine to be identified and the crystal polymorph of the particles to be controlled.

Heterogeneous nucleation and nucleation period of calcium carbonate on the mica and the highly oriented pyrolytic graphite (HOPG) substrate have been investigated. Calcium carbonate was prepared by the reaction of calcium nitrate solution with sodium carbonate solution. In the reaction crystallization of calcium carbonate, calcite and vaterite were nucleated on the both substrates. We counted the number of crystalline calcium carbonate on the substrates obtained from various initial supersaturations of calcium carbonate. The number of crystals on the mica surface was much higher than on the HOPG surface. Additionally, the number of crystals on the mica was greatly affected by changing of initial supersaturation. In order to explain the difference between the mica and the HOPG surface, a possible model for the nucleation period of calcium carbonate has been discussed. The surface crystallization on the mica and the HOPG could be described by considering the supersaturation in the bulk solution and in the vicinity of substrate, separately.

Liquid–liquid interfacial crystallization was proposed as a novel method of controlling crystal shape and size of precipitated solute particles. The crystallization was performed at interface forming two separate phases of aqueous solution and organic solvent in the present study, and progressed by increase of supersaturation caused by the slightly mutual diffusion at the liquid–liquid system. This crystallization process is possible to precipitate particles at room and constant temperature without cooling or heating sources. The liquid–liquid interfacial crystallization method was able to carry out in changing the shape of the interface. A spherical shape was made by droplets in the present liquid atomization process. Crystallization started when the droplets of the solution sprayed into the organic liquid. Our research involved producing glycine porous particles by atomizing glycine solution into 1-butanol and other organic solvent with 3-fluid nozzle. The collision between the solutions in compressed air produced the micro-size droplets of glycine solution. In using 1-butanol liquid, the glycine crystallized at the glycine solution/1-butanol interface. The spherical aggregated particles were obtained in this spray granulation process. In addition, the transformation occurred from unstable β-structure to metastable α-structure with changing crystallization condition, and it was found that α- and β-structure of glycine coexist in the obtained particles from observation by X-ray powder diffraction.

Molecular dynamics simulations of supersaturated aqueous NaCl solution including the Pt(100) or NaCl(100) crystal surfaces have been performed at an average temperature of 298 K. The behavior of the NaCl cluster produced in the solution have been studied through the consideration of the water dielectric property near the crystalline surfaces for understanding the role of crystal growth on the surface. The surfaces in the solutions greatly influence heterogeneous nucleation in crystallization process. Density profile of the supersaturated solution and polarization of water molecules was calculated in order to describe the effect of the surfaces on the solution structure at the solid–liquid interfaces. The formation levels of NaCl clusters heavily depended on the water orientation at the interfaces. NaCl clusters were easily formed near the Pt(100) surface compared with the NaCl(100) surface owing to a different construction of water molecules between the platinum and NaCl surface.

Heterogeneous nucleation and crystal growth of calcium carbonate on the mica and the highly oriented pyrolytic graphite (HOPG) substrate have been investigated by means of an atomic force microscope (AFM) with a contact mode procedure. AFM observation could lead to initial crystallization processes that were amorphous and crystalline, with an intermediate state between them. Amorphous calcium carbonate deposited on surfaces could be observed as a transient precursor phase of crystal. The shape of the amorphous calcium carbonate on the substrates is indicative of final crystal shape. Classical heterogeneous nucleation theory has been considered in order to describe the surface crystallization on the mica and the HOPG. We then measured the contact angle between the amorphous calcium carbonate and the substrates. The formation energy required for the heterogeneous nucleation on the HOPG surface was 40 times higher than that on the mica surface. To explain the difference in the mica and the HOPG surface, we h...

Molecular dynamics simulations have been performed for the design of operating conditions of liquid–liquid interfacial crystallization and clarifying the crystallization mechanism. It was found that solute ions were dehydrated with diffusion of the hydration ions from solution to organic phase. There were a significant difference of the dehydration behaviour between NaCl solution/1-butanol and /2-butanone. Aggregated ions or clusters were formed by the dehydration near the solution/organic solvent interface. The number of cluster generation near NaCl solution/2-butanone interface was larger than that in the 1-butanol system. This difference originates in the interfacial structure in the NaCl solution/the each organic solvent interface.

NaCl crystals were precipitated on a liquid–liquid interface and control of the NaCl crystal shape could be realised. The interface between NaCl aqueous solution and 1-butanol, which show phase separation for small solubility of water and 1-butanol into each other, was used as a crystallization field. Asymmetric NaCl crystals could be created on the interface for changing of NaCl concentration due to mutual diffusion between two solvents. The particle size distribution could be controlled by changing the contact time between the NaCl solution and 1-butanol. The growth rate of NaCl crystals was varied with the concentration of the NaCl solution.

The effects of surface structure and solution concentration on crystal morphology have been investigated through molecular dynamics (MD) simulation in the NaCl crystallization process. Four types of crystal surface structures were prepared for simulation. The probability of ion existence suggests that the solute ions were hardly taken into flat surfaces, while they were easily taken into roughs with some kinks and steps. This is because solute ions are more stable at a kink than at a terrace. The present simulated results suggest that the mechanism of crystal growth is dependent on the solution concentration. It was demonstrated that some ions are slotted on the crystal surface at low supersaturation after moving to the crystal surface. Under high supersaturation, the clusters are formed and adsorbed on the crystal surface. When comparing the crystal growth rates of Na+ and Cl−, the attractive force of Na+ from the crystal surface was found to be larger than that of Cl−. Moreover, the repulsive force of Na+ from the crystal surface was smaller than that of Cl− in approaching the crystal surface. The adsorption of Na+ was also found to occur before that of Cl−.

The kinetics of co-crystal formation of caffeine (CF) with citric acid (CTA) was evaluated. Ball milling of CF and CTA in molar ratios of 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, and 1:4 was performed by the liquid-assisted grinding (LAG) method. The samples were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Two types of co-crystals (co-crystal-1, a 1:1 CF-CTA co-crystal; and co-crystal-2, a new co-crystal form) were obtained. The kinetic characteristics of this new co-crystal formation were assessed by calculating the ball impact energy and force using the distinct element method (DEM) simulations. The results indicated that co-crystal-2 creation occurred under a condition in which the ball impact force exceeded a certain threshold value. Moreover, the total ball impact energy was positively correlated with co-crystal formation, exhibiting a higher ball impact force than the threshold value. The kinetics of co-crystal-2 formation was almost consistent with the Jander equation. Consequently, co-crystal-2 formation could be explained according to a three-dimensional diffusion mechanism.

The separation characteristics of a rotating probability screen having non-blinding and variable sieve openings are theoretically investigated to improve the separation accuracy. The partial separation efficiency of this screen is estimated based on the probability of particle passage through the openings. The separation particle size depends on the rotational velocity of the screen and the included angle of separation rods. As the rotational velocity of the screen increases, the separation accuracy deteriorates. By applying multi-deck screen, the separation accuracy is improved to a sufficient level for practical application.

For crystallization in a solution that is one of the fabrication processes of functional particles, methods of altering particle shape with additives which are known as habit modifiers have attracted attention. The crystal habit is complicated in applications because there are many controlling parameters, such as supersaturation, concentration, types of additives. Therefore, it is necessary to clarify the mechanisms of crystal growth in order to control the crystal shape. In the present work, the influence of additives on crystal growth has been studied by experiments and simulations. In the experiment, a differential scanning calorimeter (DSC) was used for measuring the properties of clusters formed with various habit modifiers. The number of clusters increased with the concentration of habit modifiers. The formation of clusters was also investigated by molecular dynamics (MD) simulation. The simulation result agreed with the experiment result, and the formation of clusters that assembled around the additives was well demonstrated by the simulation.

The relationship between the pore size distribution and the separation characteristics of metallic filter media is investigated and a method for estimating the partial separation efficiency is proposed. First, the pore size distribution of metallic filter media is measured via the bubble point method. The broadness of the distribution depends on the type of filter media, but the distribution is found to be in accordance with a normal distribution. In addition, pore size obtained by the bubble point method and separation particle size in actual filtering operations are not consistent due to the variety of pore shapes. Thus, the correlation between the pore size and the separation particle size is determined for individual types of filter media by performing a filtration test. Then, a method for estimating partial separation efficiency based on the sieving theory is proposed and its validity is confirmed. This method can estimate the partial separation efficiency of metallic filter media via the non-destructive measurement of the pore size distribution, and so gives valuable information when selecting a suitable filter medium for filtering operations.

The simulation of flow behavior of a two-component developer in an electro-photographic equipment is performed in order to obtain knowledge about the optimum design of a development system. The particle element method taking into account the magnetic interaction between developing particles is used and the validity of the simulation method is experimentally confirmed. The spike of a magnetic brush on a magnetic roll and the shape change of the magnetic brush due to changes in the magnetic field are well expressed by the simulation. The effects of the parameters of the development equipment on the flow behavior of the developer, e.g. shape of the doctor blade, location of magnetic pole, etc., are discussed. The flow behavior of a developer changes with these parameters. There are optimum values in these parameters in order to avoid the fusion of toner particles and they are determined by the simulation. The proposed simulation gives very useful information for the design of a two-component development system.

X-ray diffraction and differential scanning calorimetry (DSC) measurements of Se and GeSe2 during ball milling have been investigated. In this study, amorphous Se and GeSe2 are synthesized by mechanical grinding (MG) recognized as a method of inducing a crystalline–amorphous phase transition. The amorphization of Se is caused from distortion between helical chains connected by van der Waals forces. The enthalpy ΔH for crystallization of Se by rapid quench is lower than that by the MG. This result suggests that the difference of ΔH corresponds to that of the structures in intermediate range. Monoclinic GeSe2 is amorphized by disordering between the connected tetrahedra. It is considered that the tetrahedral unit of GeSe2 by the MG is distorted with wide distributions. GeSe2 is completely amorphized after 4 h of grinding, and Se after 30 h in the present milling. The difference indicates that disordering between the connected tetrahedral units in monoclinic GeSe2 is induced more easily than that between chains in trigonal Se.

The simulation of flow behavior of two-component developer in electro-photographic equipment is performed to obtain knowledge about the optimum design of a development system. Particle element method taking into account the magnetic interaction between developing particles is used, and the validity of the simulation method is experimentally confirmed. The spike of magnetic brush on a magnetic roll and the shape change of magnetic brush due to changes in magnetic field are well expressed by the simulation. The effects of parameters of development equipment on the flow behavior of developer, such as shape of doctor blade and location of magnetic pole ete., are discussed. The flow behavior of developer changes with these parameters. There are optimum values in these parameters in order to avoid the fusion of toner particles and they are determined by the simulation. The proposed simulation gives very useful information for the design of two-component development system.

Interfacial crystallization, such as surface crystallization in solution (solid-liquid) and liquid-liquid crystallization, gives us an asymmetric reaction field and is a technique for morphology control of crystals. In the liquid-liquid crystallization, the concentration distribution of solute ions and solvent molecules at the liquid-liquid interface directly relates to nucleation, crystal growth, and crystal morphology. Nonequilibrium molecular dynamics (MD) simulations have been performed at interfaces in NaCl solution/1-butanol and KCl solution/1-butanol system in order to clarify diffusion behavior of solute ions and solvent molecules. As simulation results, the hydrated solute ions were dehydrated with the diffusion of water from solution phase into 1-butanol phase. The different dehydration behaviors between NaCl and KCl solution can be also obtained from MD simulation results. Aggregated ions or clusters were formed by the dehydration near the solution/1-butanol interface. By comparison on the normalized number of total solute ions, the size and number of generated cluster in KCl solution/1-butanol interface are larger than those in the NaCl system. This originates in the difference hydration structures in the each solute ion.