The success of semiconductors today was not always smooth sailing. Today we have so far overcome the several waves of the semiconductor market and the technological barriers. The biggest event was the alarm issued in 2005 as Paradigm Shift 45. Problems were pointed out in all cases of 45 nm scaling, 45 cm larger wafer, and 45 μm thinning. Various countermeasures have been taken to overcome those paradigm changes. The development method of semiconductor devices was divided into three directions: More Moore, More than Moore, and Beyond CMOS, and at this time, discussions on SiP or SoC have begun. It has been overcome by the desperate efforts of industry-government-academia related to semiconductors. Mechanical engineering also contributed at this time. Overcoming the 2005 paradigm, challenging a new paradigm cliff in 2020, and now semiconductors are about to challenge a new paradigm revolution towards 2030. Mechanical engineering also needs new support 2.0. This paper discusses past examples of mechanical engineering support and expectations for future support. "Semiconductors are forever immortal as long as human being desires," and mechanical engineering will continue to support them forever as long as semiconductors desire.

Cleaning phenomena in semiconductor manufacturing is about the nanoparticles being removed out from, or re-adhering to, or returning to the wafer surface. However, these residual nanoparticles from polishing slurry on the wafer are usually inspected before-and-after cleaning process, not during the wet cleaning process. Accordingly, these cleaning phenomena mechanism on the surface have already not clearly known. Therefore, we have been establishing dynamically visualization of wet cleaning phenomena on the surface applying localized light called evanescent light that is generated by an optically internal reflection. This report introduces some of observed physical characteristical phenomena during duplicated scrub cleaning process of 10 and 30 nm gold particles by PVA brushes without and with skin layer, which have different contact area ratio on the surface being cleaned.

PVA brushes are widely used for semiconductor device manufacturing. The brushes can be removed nano-sized particles so that the brushes behavior near a contacting surface is important. In this study, the existence ratio near surface and deformation of the roller type brushes were experimentally observed by high-speed photography. A convex lens and evanescent fields were utilized for the definition of the depth of the observation. As a result, the reduction of the existence ratio by starting the brush rotation was observed. We also found the large compression of a nodule at the time of contact was observed compared with the simple pressing. This result suggests that the removal of nano-sized particles carried out noncontact condition, i.e., fluid absorption and desorption due to the volume change of nodules.

The particle adhesion behavior on a rotating wafer during rotation cleaning was investigated experimentally. Acrylic plate with Si surface treatment was used as a test plate. A high-speed camera was set under the acrylic plate for recording the adhesion behavior of the particles. Adhesion rate was measured from the images captured by high-speed camera. As a result, it was confirmed that the particles adhered in proportion to time. Increasing rate of the number of adhered particles did not depend on the radial positions. Also, particle size did not depend on the adhesion characteristics. In addition, the behavior of dropped droplet containing the particles on the liquid film flow formed on the rotating plate was investigated. It was confirmed that the particles contained in the droplet adhered to the plate surface. This results suggested that the particles contained in the droplets were penetrated into the laminar sub-layer.

Slurries for chemical mechanical polishing (CMP) are aqueous solutions that contain an abrasive, an oxidant, a complexation reagent, a corrosion inhibitor, and a pH conditioner. In advanced metal CMP, the CMP mechanism proceeds through metal complex layer formation by the oxidizer and complexation reagent, and removal of the metal-complex layer by abrasive friction. H₂O₂ is commonly used as an oxidant in slurries and benzotriazole (BTA) is a typical corrosion inhibitor. Full understanding of surface chemistry in mixtures of H₂O₂ and BTA is crucial to develop new slurries as well as advanced planarization processes. The removal Co has been recently acquiring a crucial interest in view of its application to Cu capping and lower level local interconnect, whereas a very limited number of studies have been reported for CMP wet chemistry of Co. In this work, the growth of a passivation layer on Co in aqueous solutions containing a corrosion inhibitor and an oxidation reagent was studied.

In this study, we investigated the behavior of EHD flow generated at small pore on ion exchange membrane. The flow velocity, and the frequency of flow generation were investigated by using different type the of electrodes. The different flow behavior was observed by changing the electrode. Gold and copper electrodes flowed only from the anode to the cathode, while nickel and zinc electrodes also flowed from the cathode to the anode. Furthermore, it was found that the maximum velocity of the flow was different for each electrode. It was also found that the flow generation frequency was different for each electrode.

A neural network using CNN was constructed to visualize the dead cell rate and volume concentration of yeast cells, and accuracy verification was performed using test data by simulation. Regarding the construction of CNN, the normalized imaginary impedance Ψ was used as the input. When actually learning, it was observed that the model loss converged around 1000 learning times. In addition, when the dead cell rate and volume concentration were visualized using test data, it was confirmed that the accuracy of 1 or 2 cell regions was high, but that of 3 or 4 cells was low. In addition, when the accuracy is quantitatively verified, the image error shows a value as close to 0 as possible in the most accurate data, and the highest image error is IQ = 0.064 [-] for the dead cell rate and IQ = 0.012 [-] for the volume concentration. From this result, it was found that this method is useful when the number of cell regions is small, but there is room for improvement when the number of cell regions is large.

As a method for identifying cell types, a comb-shaped impedance sensor was used to quantify the ion flux via the ion channel by changing the ion concentration around the cell over time. However, in cancerous cells and asymmetric neurons, the ion concentration is spatially distributed, so it is necessary to capture it as a two-dimensional density image. In order to visualize the spatiotemporal distribution of ion concentration around cell, electrical impedance tomography (EIT) is carried out using a newly developed tiny multiple-electrode sensor. The developed tiny multipleelectrode sensor has 8 electrodes with a length of 0.40 mm and a width of 0.15 mm and 1.0 mm in sensing diameter. In experiment, ion concentration around cell spheroid which is constructed using WT type of MRC-5 cells is visualized by EIT on the tiny multiple-electrode sensor. As a result, it was confirmed that spatiotemporal distribution of ion concentration around the cell spheroid increased with the passage of time, and it is successfully visualized by EIT with the tiny multiple-electrode sensor.

In medical and pharmacological studies, it is necessary to investigate efficacy of drug candidates under development. Conventionally, cell-based assays using human cells are widely carried out as an alternative method to animal tests in vitro. However, it is difficult to evaluate the effectiveness over time of drugs using conventional methods which are not capable of measuring cell dynamics. So far, we propose microfluidic devices integrated with a glucose sensor for measurement of cell dynamics. Because cells consume glucose as an energy source, glucose consumption is an important indicator related to cell’s activities. In this study, we aim to develop a microfluidic device integrated with a glucose dehydrogenase （GDH）based glucose sensor with a dialysis membrane for long-term online measurement of cell activities. We evaluated function of a GDH-based glucose sensor with a dialysis membrane for long-term measurement. The results showed that dialysis membranes prevent dissolving the mediators into solutions, suggesting that it is possible to measure cell dynamics long-term on-line on the microfluidic device.

Cell therapy is one of the most promising treatment for patients of organ failure. The cells for treatment are transported or injected into an organ directly or a vascular by continuous perfusion. However, the cell injection procedure potentially leads to aggregate formation and necrotic cores due to high cell density at the vessels. In this study, we investigated clogging and aggregate process in the micro channel imitated a branch of the vessels with experiments and a numerical method using a two-way CFD-DEM coupling method to improve cell therapy procedures.

We numerically study the three-dimensional hydrodynamic instability on spatiotemporal dynamics of a liquid film flow produced by the generalized two-dimensional Kuramoto-Sivashinsky (2D gKS) equation from a viewpoint of symbolic dynamics. The unstable liquid film flow gives rise to a rich variety of hydrodynamic instabilities such as three-dimensional hydrodynamic instability and spatiotemporal structures forming horseshoe-like and pointed structures. We study the wave dynamics by the estimating the dispersion entropy based on symbolic dynamics and statistics.

We experimentally study the nonlinear dynamics of thermoacoustic combustion oscillations in a swirl-stabilized turbulent combustor using complex network theory. We simultaneously measure the pressure fluctuations, OH^* chemiluminescence emission intensity fluctuations, and velocity fluctuations inside the combustor. We examine the spatiotemporal distribution of acoustic source clusters in a thermoacoustic power network. The driving region for thermoacoustic combustion oscillations is clearly identified by the thermoacoustic power network.

We numerically study the effect of mole production on high-frequency combustion oscillations in a model rocket engine combustor based on an analysis of the budgets of acoustic energy and complex network theory. The extended local Rayleigh index considering mole production allows us to examine the effect of mole production on combustion oscillations. Mole production fluctuations have an effect on damping high-frequency combustion oscillations in the shear layer between the outer hydrogen jet and the inner oxidizer jet. The acoustic energy networks can characterize the complex acoustic energy budgets of a flow field during combustion oscillations. Temporal evolutions of the average vertex strength in the acoustic energy networks can estimate the activity of the acoustic energy transport. The damping sources of the acoustic energy on the mole production term are clearly associated with the driving sources of the acoustic energy on the heat release term during high-frequency combustion oscillations.

The effects of co-doping in phosphors and the use of co-doped phosphors to extend the temperature measurement range were experimentally investigated in terms of the lifetime method. Such effects can be evaluated by comparing the single and double luminescent centers. In this study, YAG:Tb, YAG:Cr and YAG:Cr,Tb were prepared by sol-gel method and the luminescence intensity was measured under excitation by the 4^th harmonic of Nd:YAG laser. In order to improve the temperature measurement performance of YAG:Cr,Tb, it is desirable to divide it into two wavelength regions with a threshold around 600 nm, and to switch between the two regions depending on the temperature range when performing temperature measurement by the lifetime method. The absolute lifetime sensitivity S_A is a suitable index to use when dividing the temperature region into two regions, resulting in switching at around 800 K. The lifetime of the Cr-derived luminescence is slightly longer, while that of the Tb-derived luminescence is about 10 times shorter.

The purpose of this study was to improve the accuracy of knock detection for lean burn SI engines. In this study, we conducted an experiment to observe autoignition in an engine cylinder using a borescope and a high-speed camera under an air excess ratio of 2.1. In addition, the resonance frequency of each vibration mode by knocking and the knock intensity were also calculated from the in-cylinder pressure history. Autoignition was optically observed in all cycles with a knock intensity of more than 20 kPa or more, and in some cycles with that of less than 20 kPa. We compared the vibration caused by combustion and it caused by autoignition. As a result, by distinguishing between the vibration caused by combustion and it caused by autoignition using window functions, a knocking cycle that could not be detected by the conventional index was detected.

The chemical reaction between polymer (HPAM) and Al³⁺ aqua complex showed a temporary increase in viscoelasticity. We found two different mechanisms. One was similar to that of Ueki et al. (Fe³⁺ aqua complex), but the other was found only in the Al³⁺ aqua complex. I suggest a reaction mechanism that results from a different hydrolysis equilibrium of the Al³⁺ aqua complex than the Fe³⁺ aqua complex.

Viscous fingering (VF) occurs when a less viscous fluid displaces a more viscous one in porous media. It has been recently reported that a partially miscible VF has experimentally shown to change to multiple droplets pattern. However, in the present study, we have experimentally shown a partially miscible VF can have the potential to stabilize the interface more effectively, namely, leading to circular-like pattern in a radial geometry. This is caused by a high rate of the spinodal decomposition.

Recently, the development project of A-USC plants which have superior efficiency compared with USC plants have been underway from the requirement of the energy mix. Nickel-base heat resistant alloys are being considered as a candidate for their structural materials. In the A-USC plants, the structural materials used in the hot section undergo not only creep damage during the steady-state operation at elevated temperatures but also creep fatigue damage due to the loading transients including startup and shutdown. Therefore, creep-fatigue interaction becomes important as a major damage mechanism for structural materials in A-USC plants, however, the remaining life assessment technique have not been established considering the creep-fatigue damage. Semi-destructive methods are considered a useful inspection method for structural materials of high temperature plants because such techniques can be applied with the miniature-sized sample that can be cut from the actual component with smallest damage. Especially, EBSD analysis has advantages because the degree of deformation or damage can be expressed quantitatively as a local change in crystal orientation. It can be expected that machine learning utilized to mine data obtained from EBSD analysis characterize the damage in actual components. In this study, a machine learning method was investigated to analyze the damage mode and remaining life of Ni-based alloys subjected to creep, high-temperature fatigue, and creep-fatigue damages.

Superior creep strength has been required in turbine wheels employed under high temperatures. Since they are produced using investment casting method, mechanical properties sometimes depend on each portion of turbine wheel due to the complex shape. Although conventional SP creep tests adopt 10mm in diameter and 0.5mm in thickness are employed to examine local properties at high temperatures, other new testing methods are required because these turbine wheels are small and have thinner thickness of blades. Employing very small, half-size of the conventional SP creep test specimen, a series of creep tests for three turbine blades of Inconel 713C were conducted where the test temperature and the applied load were fixed at 720°C and 150N. Microstructural observation shows equiaxed at tip and columnar grains at root of the blades. SP creep rupture lives of specimens sampled from the root are generally longer than those from the tip. SEM observations reveal that creep cracks developed along the grain boundary. Specimens from the root have longer columnar grains, and creep crack mainly developed along the boundary of columnar grains. Creep rupture lives depend on dendrite arm spacing; the smaller D.A.S., the longer rupture lives.

A modified CrMoV forging steel was developed to improve creep strength by adding tungsten to a conventional CrMoV forging steel. Creep damage preferentially extends at a stress concentration portion under multiaxial stress. It is necessary to clarify the creep damage extension process under multiaxial stress states. In this study, creep tests using a plain specimen and two kinds of round notch bar specimens with different notch radius (notch tip radius 0.5 mm (R0.5) and 2.0 mm (R2.0)) on the modified CrMoV forging steel were carried out. Creep rupture times of the modified CrMoV forging steel were longer than those of the conventional one. Creep rupture times of R0.5 was longer than those of R2.0 notch specimen. Although greater number of creep voids were observed around 0.5 mm from notch root in R0.5, and around center of the specimen in R2.0, they were less than those observed in the conventional one. The finite element creep analysis of the notch specimens showed the three-stress components and multiaxial coefficient took the maximum values at around 0.5 mm from notch root in R0.5, and around center of the specimen in R2.0. It was found that these tendencies correspond with those of the void number density.

Mod.9Cr-1Mo steels are widely being used for steam pipes in ultra-super critical power plants. Creep damages, such as void initiation and growth, were detected at heat affected zone (HAZ) in welding portions. It is necessary to clarify creep damage extension mechanism and life prediction method in the welded portions. In this study, round bar tensile type miniature specimens with 1mm diameter were machined from a base metal, a weld metal and a HAZ in a shieled metal arc welding pipe. Material constants of Norton’s law were determined from creep tests using the miniature specimens. Creep tests were also conducted using standard size welded joint creep specimens taken from the pipe. The welded joint specimens were failed at the HAZ and rupture times of the weld joints were shorter than those of the base metals. Void initiation and growth were observed at the HAZ. A finite element creep analysis for the welded joint specimen was performed using material constants obtained by the miniature specimens. It indicated that higher stress and creep strain concentrate at the HAZ causing void initiation and shorter rupture time than the base metal.

In this research, we improved on a fatigue test machine based on the published fatigue test method for copper alloy strips, examining and modifying each unstable element, shortening the test time and performing stable 10⁸ fatigue cycle tests. Then, the strip fatigue test was conducted using the improved fatigue test machine. As a result, it was confirmed that the fatigue cycle was improved in the transverse direction specimen of the copper alloy strip, and the cause was examined by observing the fracture surface. The location of the crack was identified, and it was confirmed that it was consistent with the FEM analysis.

In this study, we proposed a method of forming Fe-Al intermetallic compound layers on the surface of an additive-manufactured maraging steel via Atmospheric-controlled Induction Heating Fine Particle Peening (AIH-FPP) treatment. The surfaces of the steel were modified by AIH-FPP treatment, wherein the steel particles were coated with the Al particles by mechanical milling. Scanning electron microscopy and energy dispersive X-ray spectroscopy revealed that the Al particles were deposited on the surface of the substrate by AIH-FPP treatment. The intermetallic compound layers were formed by heating the substrate after AIH-FPP treatment. The elemental composition of the surface of the substrate indicated that the formed intermetallic compound layers consisted mainly of FeAl. The intermetallic compound layers were presumably formed by the diffusion of the surface deposited the Al particles into the substrate. Moreover, the AIH-FPP-treated surfaces showed high abrasion resistance owing to the existence of the intermetallic compound layers.

The shear test and cantilever bending one for the single column of a suspension plasma sprayed thermal barrier coating (SPS-TBC) were carried out to evaluate the mechanical properties of the single column. The fracture of the single column occurred at the porous layer in the column near the top-coat/bond-coat (TC/BC) interface in the shear test. The cantilever bending test revealed that the SPS-TBC has a low Young’s modulus in the out-of-plane direction (E_o) compared with that in the in-plane direction and a strong anisotropy in the elastic modulus. The shear strength and E_o of the single column increased with thermal exposure, and the increasing ratio of shear strength was higher than that of E_o. It was found from the FEM analysis result that Young’s modulus of porous layer (E_p) is as low as 0.1% that of the dense layer (E_d). From these results, it was concluded that, in the SPS-TBC, the mechanical properties and their change by the thermal exposure are dominated by the mechanical properties of the porous layer within the single column. These results suggest that SPS-TBC has superior thermal cyclic resistance.

Welding is a joining method in used for various structures. Since heat is applied locally to the material in welding, tensile residual stress is generated near the bead, causes the stress corrosion cracking in stainless steel. Therefore, it is important to develop a method of welding residual stress reduction. We have proposed the method loading ultrasonic vibration for base material during the welding. The advantage of this method is to reduce the residual stress easily in short time. In this study, effects of acceleration amplitude on welding residual stress reduction using block material SUS304 is investigated-

Welding is the joining method using locally given heat. Residual stress is generated near the bead and it degrades fatigue strength. A reduction method of residual stress in a short duration and low costs using ultrasonic vibration load during welding has been investigated. Build up welding was done for a block metal that is rolled steel for general structures SS400 by this method, and was measured residual stress by X-ray residual stress measurement device. In this study, effectiveness of ultrasonic vibration load for welding is investigated.

A5052 aluminum alloy sheets and C1100 copper sheets were welded by friction stir spot welding with various tool plunge depth. A tensile shear test and a cross tension test were performed to investigate the effect of the tool plunge depth on the tensile properties of the joint. When the welding was performed using the tool plunge depth more than 1.9 mm, hooks were formed at edge of the welded area. As a result of the tensile shear test, the fracture load tended to increase as the tool plunge depth increased. When the tool plunge depth was less than 1.8 mm, the fracture occurred at the aluminum base metal, and when the tool plunge depth was more than 1.9 mm, the fracture occurred with the hook. As a result of the cross tension test, when the tool plunge depth was less than 1.8 mm, the fracture occurred at the welding interface, and when the tool plunge depth was more than 1.9 mm, the fracture occurred at the hook. The fracture load tended to increase more than 1.9 mm of the tool plunge depth.

To realize carbon fiber reinforced plastic (CFPR) mirror for a space telescope, high-precision polishing of the epoxy resin surface, which is the reflective surface of the mirror, is required. For this purpose, it is necessary to know the polishing characteristics, such as removal rate and surface roughness, of epoxy resin. Our previous polishing experiment of epoxy and acrylic resins showed that the removal rate of epoxy resin was approximately 90% lower than that of acrylic resin. In the present study, to clarify th reason for the differences in removal rate between these two resins, indentation and micro-scratch tests were carried out. The micro-scratch test enables to provide the shear strength of resin by acting a shear force on its surface. As a result, there was no significant differences in indentation hardness between epoxy and acrylic resins. However, the micro-scratch test revealed that the shear strength of epoxy resin was 67.5% higher than that of acrylic resin. These findings indicate that the difference in removal rate between the two resins is mainly due to the difference in the shear strength between the resin surfaces.

Composites of bioabsorbable poly(lactic acid) (PLA) and bioactive β-tricalcium phosphate (β-TCP) have attracted attention as alternative material to metal bone fixation device. It was previously reported our group that the mechanical properties of this composites are improved by tensile drawing. And, the transformation molecular orientation and crystallinity during drawing evaluated. However, effects of orientation behavior with annealing included in drawing has not been clarified. In this study, orientation behavior of this composite materials with annealing and tensile drawing was focused. β-TCP/PLA composites which β-TCP content is 0 to 30 mass% was drawn to draw ratio 1.0 and 1.5 at 70 °C. Orientation function was calculated using Infrared dichroic ratio from absorbance obtained by Fourier transform infrared spectroscopy. As a result, in the without treatment state, the composites were almost amorphous, the behavior of α crystal formation was observed with annealing and drawing. This result suggests the increase of strength is due to α crystal.

It is well known that temperature of rubber varies when it is deformed, as the Gough-Joule effect. Although compressed parts are often made from rubber, the temperature variation of rubber under compression has not been studied well. Studying temperature variation of rubber is important for efficient use of rubber. In this study, we studied a temperature variation of urethane rubber subjected to a uniaxial compressive loading. First, the temperature was measured at the center and at the sides with thermocouple, and radiation thermometer. Second, a stress relaxation test was conducted. As a result, in the first experiment, temperature increments of 1.4 ℃ at the center and 0.8 ℃ at the side of the specimen were confirmed during compression. There was little difference between values measured with thermocouple and radiation thermometer. In the second experiment, the experiment value was larger than our theoretical one by 0.5 ℃ at most.

Recently, many new technologies development relating to seismic design of bridge piers for the earthquakes have been produced. From this reason, the seismic performance has been improved. When an earthquake is generated for the Rahmen structure, bending failure occurs at the base and shear deformation occurs at the center of the beam. Normally, metal materials can absorb the energy by being plasticized from earthquakes. However, when shear buckling is happened, the hysteresis of the material can’t be maintained and the amount of absorbed energy decrease. In this research, we focus on the Rahmen structure, simulate nonlinear Finite Element Method (FEM) “Marc” and test that imitated the center of the beam. By carrying out a four-point shear experiment using this test piece, we aim to reproduce shear deformation. This experiment can confirm the decrease in absorbed energy. Furthermore, absorbed energy can be suppressed by applying appropriate reinforcement.

Most of the bridges were constructed while the high economic growth period in Japan. These has many damages what due to corrosion and aging. The main cause of bridge damage is fatigue cracks in stress concentration area. Because of that, it is important to control the growth of fatigue cracks for a long time. These cracks usually occur from the stress concentration at the corner and the heat stress area by the welding heat and so on. And these are growing due to the vibration. When a crack length reaches the limit, it is called an unstable fracture state. Then, it cannot be controlled.

The aims of this study are to relax the stress of stress concentrated part and to suppression crack growth. We could perform relaxation in the stress of stress concentrated part by using the piezoelectric actuator as a method of suppressing crack growth. However, if the piezoelectric actuator adhered to the test piece directly, a problem arises. As problems, the amount of deformation escapes to the outside, or repeating attachment and detachment damages the piezoelectric actuator. It is necessary to show method of locally and efficiently compressing the stress concentration part and detachable. Therefore, we developed the device of compressive stress field that is easy to set. By using this device, it is easy to control the stress fields so that compression and tension occur locally and simply. We will confirm prolonging life of the material by performing fatigue test, using this device.

This study aims to calculate the transition zone parameter, that is used in the formulation of phase-field crack (PFC) model, using molecular dynamics (MD) simulation, and use the value into PFC simulation. Firstly, a quantitative evaluation of intactness is conducted by examining the distribution of local densities, which are calculated within a representative volume in a molecular dynamics model based on the information of coordinates of the atoms. The variety in these local densities are triggered by crack propagation, which shows the difference in conformations between the region near the crack and the region distant from the crack. The spatial distribution of the intactness is fitted to an exponential curve by least squares method. From this distribution, the value of transition zone parameter is estimated. The result of PFC simulation using this newly determined value of transition zone parameter is compared to the result of MD simulation. Discussion is made in terms of the geometry of crack path.

Ices show many crystal structures depending on the external conditions, such as temperature, pressure. It is known that, when water is confined to the environment at the nanoscale, they show peculiar crystal structures not seen in bulk water due to the spatial limitation. In this research, we focus on the system confined to the slit nanopore, which is called quasi-2-dimensional (Q2D) system. Several Q2D ices are reported in the literature, and they are classified by the number of layers, such as monolayer (ML) ices, bilayer (BL) ices, trilayer (TL) ices, and multilayer ices. Until now, many ML ices and BL ices are reported in the literature. However, few TL ices or multilayer ices are reported in spite of their high structural degrees of freedom. Therefore, we performed molecular dynamics (MD) simulation of water in slit nanopore and explored crystal structures of Q2D TL or multilayer ices. In order to explore the crystal structure of ice, we used replica exchange method, which enables us to explore various states of the system efficiently without being trapped in local minimum. Performing replica exchange MD simulations, we found several TL ices and multilayer ices, and revealed their peculiar crystal structures.

Water-ethanol separation is one of the most important processes for producting pure bioethanol. Nevertheless, this separation is difficult process due to their near boiling point. The most general method for the water-ethanol complete separation is azeotropic distillation. However, this distillation consumes largeamount of energy which is equal to nearly half of energy on ethanol combustion. Therefore, to improve the water-ethanol separation process is still important issues. Carbon nanotubes(CNTs) are one of themost expected material to apply to separation membranes due to their nanopores. Recent investigations have demonstrated that water molecules in CNTs under axial electric field forms specific helical struc-tures and exclude alcohol molecules from CNTs using molecular dynamics(MD) simulation. Therefore,the combination of CNTs and axial electric fields can be used to water-alcohol separation. However,it is not easy to apply strong electric fields in nanoscale spaces. Hence, in this study, we investigated water-ethanol separation performance of tip functionalized(tip-charged) CNTs using MD simulation.

High-heat-flux cooling devices have been attracting attention due to the increasing power density of semiconductor devices. Nanoporous membrane-based evaporative cooling devices were recently reported which can dissipate a heat flux of ~1 kW/cm2. The optimized design of these devices requires the understanding of the non-equilibrium gas flow near a liquid–vapor interface, which is called the Knudsen layer. Although the one-dimensional Knudsen layer has been intensively investigated, the two- and three-dimensional Knudsen layers are not well understood because the change in the interfacial shape and position affects the overall heat and mass transfer flux in evaporation from a nanoporous membrane. In this study, we clarify how the evaporating flow velocity, the shape and position of the liquid–vapor interface, and the Knudsen number affect the number density at downstream and the apparent mass accommodation coefficient at the porous outlet.

Polymers of intrinsic microporosity (PIMs) have recently attracted much attention as gas separation membranes in terms of scalability, low energy cost, and environmental friendliness. In the present study, we investigate the solution–diffusion processes of CO₂, N₂, and CH₄ molecules in PIM-1 based membranes (PIM-1 and PIM-1/a-SiO₂) using molecular dynamics (MD) and grand canonical Monte Carlo (GCMC) simulations. Long-time diffusion is characterized via the mean squared displacements of gas molecules, indicating that it takes them over 50 ns to reach normal diffusion in the PIM-1 based membranes. Specifically, systems with unimodal pore size distributions (PSDs) are likely to cause the gas molecules to reach normal diffusion within the time window of 50 ns, while systems with multimodal PSDs lead to sub- or super-diffusion of the molecules in that time window. Compared with bulk PIM-1 systems, the solubility of gas molecules is increased in PIM-1/a-SiO₂ systems; in particular, CO₂ solubility is significantly increased. This is because the amount of CO₂ molecules adsorbed in the vicinity of a PIM-1/a-SiO₂ interface increases due to an energetic affinity of CO₂ with surface OH groups. The diffusivity of N₂ and CH₄ is increased in the PIM-1/a-SiO₂ systems due to large voids created by the presence of the interface. Meanwhile, CO₂ diffusivity decreases due to an energetic affinity with the OH groups.

Water confined in nano-space show peculiar features which do not appear in bulk system. Carbon nanotubes (CNTs) are promising materials as nano pore due to their uniform structures and rich variation. The behavior of water confined in CNT has been studied to apply the features to engineering. Recently, a peculiar peak was observed in the spectra of water confined in CNT by infrared spectroscopy, which does not appear in the spectra of bulk systems. While molecular simulation is a useful method to study nano-scale phenomena, it still proved to be insufficient to identify the mechanism, because it is impossible to simulate anharmonic vibrations of water molecules using ordinal harmonic potentials. In this study, molecular dynamics simulation with modified water model that generates anharmonic vibration was carried out and the relationship between vibrational frequencies and the distributions of water molecules inside CNT was analyzed. The high vibrational frequencies that correspond to the peculiar peak were confirmed from water molecules located near the carbon atoms of CNT.

This study focused on applying reactive molecular dynamics simulations to computer simulations of the pyrolysis reaction of cellulose, which is the main component of biomass. Reactive molecular dynamics simulations were performed using the ReaxFF package implemented within LAMMPS for large-scale parallel molecular dynamics calculations. The cellulose molecular model is composed of a total of 25,212 atoms using 6 cellulose chains formed by binding 1,4-β-D-glucopyranose at a degree of polymerization of 200. The cellulose molecular model used in the simulation was equilibrated to the final equilibrium conditions (500 K, 1 atm) by a predetermined method. Simulations were performed at seven relatively high temperatures (1000, 1300, 1500, 1800, 2000, 2300, 2500) in order to observe a sufficient pyrolysis reaction at a limited computational cost. In order to analyze the pyrolysis characteristics and reaction mechanism of cellulose by reaction molecular dynamics simulation, reaction products, formation behavior, and the dependence on simulation temperature was evaluated. The simulation results showed results that are consistent with the basic properties of cellulose for the pyrolysis reaction, which is well known in previous studies, in the reaction molecular dynamics simulation. In particular, cleavage of the glycosidic bond was a common reaction in the first step of cellulose, and it was found that the amount of C6 and C12 products produced was large. It was also suggested that C6 is a product derived from the glucose ring of cellulose, and that many of the important products from cellulose are produced through the cleavage of the glucose ring.

Ab initio molecular dynamics simulation is an effective method to obtain vibrational spectra, but it is known that there is a difficulty in the accuracy of van der Waals interaction. In this study, the effect of the correction for van der Waals interactions on the vibrational spectra of clathrate hydrates was examined, where hydrophobic interactions are important. As a result, it was found that the vibrational frequencies of the clathrate hydrates became smaller than those of PBE with the correction. However, vdw-DF2 and vdw-DF3-opt2 were found to reproduce the experimentally measured vibration frequency trends well.

The International Space Station (ISS) procures water through the resupply and water recovery systems. For future human space exploration, it is required to increase the regeneration rate of water once brought and reduce the amount of resupply from the ground. Iodine or silver are used to disinfect the water on the ISS. In this situation, the biocide adding the recycled water is also consumable which need to supply from the ground. In recent years, the bactericidal action of ultrafine bubble water has attracted attention, and its application to various fields is progressing. It is expected that this can be utilized as a technology for water regeneration in space. For space application, simple and effective one is desirable. However, the properties of the ultrafine bubbles are still veiled. As a first step to understand and apply the ultrafine bubbles to space applications, we elucidated the relationship between the flow rate and the number density of ultrafine bubbles generated by the simple ultrafine bubble generator.

Thermodynamic phenomena such as Soret effect, Thermo polarization effect, and Thermo osmosis slip received many attractions recently. These phenomena can be used for mass transport, harvesting energy from waste, and destroying cancer cells. Because heat flux is responsible for these effects, controlling heat flux by external forces enables to control these phenomena. Heat conduction is expressed by Fourier’s law on macroscopic perspective. On the other hand, on a micro scale, molecular interactions dominated by molecular positions and orientations have a key role in controlling heat and mass transport. Generally, it is difficult to control the position of the molecule, but there are several methods to control the molecular orientation. However, it has not yet been clarified what molecular parameters affect the creation of an ordered structure to control the thermal conductivity. Polar and nonpolar fluid mixtures have the dependences of diffusivities and molecular orientations on the dipolar strength and the mole fraction of polar molecules. In addition, molecular asymmetry induces the alignment of the molecular axis along the heat flux. Here using non-equilibrium molecular dynamics simulation, we examined the influence of the fraction and the asymmetry of polar molecules on the heat transport of polar and nonpolar fluid mixtures. We find that by making polar molecules asymmetric and decreasing the mole fraction, polar molecules form clusters. As a result, the diffusivities decreased, and thermal gradient increased.

Research to elucidate the mechanism of biomembrane fusion has attracted considerable attention because it has been applied to various fields, such as the elucidation of viral infection mechanisms and the development of drug delivery methods. In this study, we used dissipative particle dynamics (DPD) to observe the fusion of biomembranes caused by vesicle collisions at various size scales. As a result, it was found that the fusion of biomembranes depends on the size of vesicles and the repulsive parameter of DPD, and it is divided into the case of fusion and the case of non-fusion. In addition, when the vesicle system was large, it was observed that there was a wave motion of the membrane that was not observed in the small system. This wave motion may cause the biomembranes to bond to each other, suggesting that membrane fusion may occur in a way that has not been discussed before.

Tetra-arm polyethylene glycol(Tetra-PEG) gels are formed by cross-linking of two types of tetra-armed star polymers, and are expected to be applied as a biomaterials because of its high mechanical strength and biocompatibility. In order to insert the gel into the body, it is necessary to prepare the gel in a dilute system to prevent swelling, but there is a problem that it takes a long time for the gelation in a dilute system. In this study, we focused on the molecular crowding effect that accelerates the reaction in dilute systems, and analyzed the effect on gelation by reproducing the molecular crowding environment by introducing a large amount of guest polymer that does not react with Tetra-PEG prepolymer into the system. As a result, it was confirmed that the addition of the guest polymer changed the gelation process in the dilute system and shortened the gelation time.

We investigate the structure and rheological properties of dilute colloid-polymer mixtures at rest and under shear via molecular simulations that take into account hydrodynamic interactions. Mixtures of amphiphilic Janus colloids (JCs) and hydrophobic/amphiphilic polymers are considered for various solvent qualities and polymer concentrations. Free polymers, small colloidal micelles, and small hybrid aggregates coexist in mixtures with slightly hydrophobic homopolymers. As the solvent quality worsens, all polymers aggregate into small droplets, covered and stabilized by the JCs. In mixtures with amphiphilic polymers, we observe the coexistence of free polymers, purely polymeric micelles, and hybrid aggregates. At small shear rates, all mixtures exhibit a Newtonian-like response with intrinsic shear viscosities that are up to two times as large as of pure suspensions of non-adsorbing colloids at the same concentration. Further, the mean aggregation number increases slightly due to the flow-enhanced collision of aggregates. At larger shear rates, however, the aggregates break up, the polymers align in the flow direction, and the mixtures become shear-thinning. This shear-induced breakup occurs at stronger shear compared to pure JC suspensions, indicating that the adsorbed polymers reinforce the hybrid aggregates.

We investigate the mechanical properties of π-conjugated polymeric materials composed of regioregular poly(3-hexylthiophene) (P3HT) and fullerene C₆₀ using coarse-grained molecular dynamics simulations. Specifically, we perform tensile simulations of P3HT:C₆₀ composites with varied degrees of polymerization and C₆₀ mass fractions to obtain their stress–strain responses. Decomposition of stress tensor into kinetic energy and virial contributions indicates that the tensile moduli of the pure P3HT samples are greatly dependent on non-bonded interactions and on bonded interactions associated with bond-stretching, while the addition of C₆₀ leads to an increase in the tensile modulus originating from enhanced non-bonded interactions associated with C₆₀. Additionally, the tensile strength of the P3HT:C₆₀ samples correlates well with molecular chain entanglements, which are characterized by the average number of kinks per chain obtained from primitive path analysis. We also find that the upper and lower yield points characterizing strain softening become more pronounced with increasing C₆₀ mass fraction. Persistent homology analysis indicates that the emergence of the yield points correlates well with the coalescence of microvoids in the course of tensile deformation, resulting in the generation of larger voids.

Blue phases (BPs) are three-dimensional self-assembly structures of liquid crystals with a lattice of line defects. They have attracted considerable interest as the potential in next generation displays. It is well known that BPs occur in cholesteric liquid crystals (CLCs) under certain thermodynamic conditions. However, previous studies have indicated that confining surfaces may induce distinctive structural changes. For example, a quasi-two-dimensional (Q2D) confinement system was investigated with the aid of numerical calculations, and a stable Q2D Skyrmion structure was attained. In this study, we investigated the CLC phase behavior at the molecular scale for a quasi-one-dimensional (Q1D) nanotube system using molecular simulations. We observed the various morphological behaviors of CLCs by changing the temperature and the radius of nanotube. Specially, we discovered a self-assembly structures with cylindrical defects rather than lines by introducing a novel local orientation analysis. Our results show that the self-assembly of CLCs offers a guide to control the intensity in one-dimensional confinement and fundamental knowledge for application to optical devices.

Phase transition of anisotropic materials is studied in physics, materials science, engineering and biology. However, its dynamical process is still elusive. In this work, we investigate the transition of a liquid crystal from a nematic to a smectic phase. A combination of molecular dynamics simulation and machine learning successfully identifies the formation of pre-transitional local structures that precede critical smectic nuclei.

The experimental studies were performed to clarify the upper and lower boundaries of the fan. A crossflow fan is rotated in the open space, i.e. without casing. The fan diameter is 78 mm. The impeller includes 29. The blade angles at the inside and the outside are 90 and 150 degrees, respectively. The experiments were conducted under three conditions of the upper and lower boundaries of the fan: lower wall only, upper and lower wall, and no wall. The amplitude fluctuation at the impeller outlet are measured using a hot-wire anemometry. FFT analysis and the phase difference show that forward and backward vibration of one cell occurs under each condition. It became clear that the fluctuation tended to turn forward due to the upper and lower boundary walls of the fan. The calculation results show the mechanism, what changes the forward or backward direction and makes eccentric vortexes.

In this study, computational fluid dynamics (ANSYS-Fluent 2019 R3, ANSYS-CFX 2020 R1) were used to investigate fluid vibrations in the low flow region of axial fans. Previous studies have shown that reverse rotational vibrations occur near the fan blades at low flow rates. The vibration of the fluid propagated in the circumferential direction on the tip side. The vibration of the fluid did not rotate on the hub side but was transmitted in the opposite direction from the hub side to the chip side on the envelope. In this study, based on what was assumed in the previous study at a blade frequency of 20 Hz, 2D and 3D calculations were performed in the region around the blade, and the fluid in the low flow region when the blade frequency was changed to 15 Hz. The vibration was visualized, and the propagation process between blades and the propagation in the envelope direction were investigated.