In this study, we studied gripping comfort criteria based on grasping simulations using three hand finite element models with different hand sizes. Three individual hand finite element models with dimensions of 5^th%ile, 50^th%ile and 95^th%ile of Japanese adult male were utilized to simulate grasping motion and to obtain contact pressure distribution during grasping. To generate a dataset of contact pressure distribution, grasping simulations with 60 different conditions (3 diameters of cylindrical object × 5 subjects × 4 positions of the thumb) were conducted. Gripping comfort scores under each condition were calculated by assigning the contact pressure result acquired from the simulation into the regression equation reported in our previous study. According to analysis result, contact pressure distribution was varied by the position of the thumb. However, gripping comfort score was not significantly affected by the position of the thumb as well as the diameter of the cylindrical object used in this study.

In endovascular treatment, extracting more information from X-ray image can contribute to perform more safe treatment. In this study, we propose the reconstruction method of 3D configuration of wire-like device from single X-ray image. Based on the 3D vessel model after 2D/3D registration and the line connecting between X-ray source and image, a part of the line crossing the 3D vessel model is calculated. the part of the line is the range in which the device is assumed to exist. By connecting the multiple ranges, the configuration of the device can be reconstructed. As the constraint condition for the reconstruction, minimizing strain energy was used. The numerical simulations to insert a guidewire were performed to evaluate the accuracy of the proposed method. And in experiments, the reconstruction of a guidewire configuration when jumping phenomenon was observed in vessel model were carried out. The accuracy of the reconstruction was about 0.3 mm. It was found that a sign of the jumping phenomenon is reflected in the strain energy and the responsiveness of the tip position. The proposed method will be able to provide more quantitative information to clinicians. This will contribute to make intravascular treatment more safe.

In endovascular treatment, guidewire and catheter manipulated manually can often damage blood vessel. One of the reasons for this is that the behavior of the device does not match the operator's expectations. We hypothesized that the ratio of the actual operation given to the device to the actual movement of the device (responsiveness) reflects the position where the device is difficult to be delivered. In order to evaluate the responsiveness, we performed numerical calculation by inserting a guidewire into the blood vessel. The vessel model consists of a combination of bent parts and straight parts. The starting point for data collection was Position A, 55 mm away from the vessel model’s entrance. The end point was set to a cerebral aneurysm (Position F) located 110 mm away from the entrance. We gave a guidewire push operations and rotation operations to deliver the guidewire from Position A to Position F. When the guidewire was located distal to the vessel model’s entrance, the responsiveness of the pushing operation at the flexion of the vessel model was found to be unaffected by the position of the guidewire (inside or outside). From the spatial distribation on the responsiveness of the rotation operation, it was found that the rotation operation should be performed in a straight part. The investigate of the distribution of responsiveness can be expected to specify the region that are difficult for physicians to operate devices in advance.

The development of pumps and mixers is important to improve the performance and multifunctionality of microfluidic systems. In particular, piezoelectric actuators are often used because they are easy to miniaturize, have excellent response, and can be controlled with high precision. In our previous work, we devised a new actuator combining a bimorph piezoelectric plate and a metal cap, and confirmed its excellent bending performance by experiments and numerical analysis. In this study, the proposed new actuator was applied to a microfluidic device with a Y-shaped channel, and the pumping and mixing performances were verified by the coupled piezoelectric-fluid transient analysis. In the pumping performance test, it was found that the pumping performance of the new actuator was improved by about 19 times compared with that of the conventional actuator. On the other hand, in the mixing performance test, the mixing index of the new actuator was improved by about 2.3 times compared with the conventional actuator. These results verify the superiority of the proposed new piezoelectric composite actuator in terms of both pumping and mixing performance in microfluidic systems.

Centrifugal pumps designed for operation in low flow rate have various application such as medical, food processing, chemicals, and manufacturing. However, the efficiency of the low flow rate pump is lower than the industrial pumps in general. Therefore, a double rotation screw pump that was different from the centrifugal one was developed to improve the pump performance. The stator of this pump passively rotates in the same direction along with the rotation of the rotor. Thus, because the rotational mechanism is simple, this pump is smaller than a general screw pump. In this report, the dependence of pump performance on number of stator stages and their material is investigated. We obtained the following results; the number of the stator stages improved pump pressure and efficiency and the pump efficiency of ABS resin stator was higher than those of titanium stator.

An effective treatment for hip osteoarthritic patients is total hip arthroplasty (THA). THA is a surgical procedure in which a painful osteoarthritic hip joint is replaced with an artificial hip joint. Joint dislocation is one of the most critical problems not only for human but also for canine THA. We have newly proposed an artificial hip joint which has a simple structure to prevent joint dislocation. The proposed joint has the structure with a femoral head partially covered with an acetabular cup. In the present study, the dislocation moment due to the impingement was assessed using finite element analysis. The dislocation moment was approximately 415, 166, and 8 N•mm in the case of the 1.5, 1.0, and 0.5 mm inset height model, respectively. This result indicates that the acetabular cup with the structure for preventing dislocation has an ability to resist the excess rotational movement which induces joint impingement.

Cervical cell harvesting instruments used in cervical cancer screening mainly there are swabs and brushes. The examination using these is almost pain-free in a short period of time, it has advantages such as early detection and treatment being possible. But, the accuracy of cell harvest is about 50-70%, not necessarily high, there are demerits such as few re-examination due to errors, too.

In this study, we can reduce re-examination due to error at the time of cell harvesting ② High harvest precision can be stabilized ③ Fiber structure that can absorb a much larger number of harvested cells than current commercial brush. Research and development of a new cervical cell harvesting instrument having such multifunctionality it is aiming. We are aiming at the research and development of a new cervical cell harvesting instrument having such multifunctionality. Then, For the sample, we used 5 types of existing commercially available brushes, 6 types of prototype braided round cross-section prototype brushes using braid technique, and 6 types of Y-shaped modifued cross-section braid prototype brushes (patent pending), and then We conducted an adsorption amount experiment using a full-scale uterine model using 2 methods (youth haevestion method and menopausal havestion method), and compared their usefulness.

The pressurized metered-dose inhaler used for inhalation therapy is believed to cause fewer side effects than oral intake because the drug can be inhaled directly, but side effects occur when the drug adheres to the oral cavity during inhalation. In this study, focusing on the adhesion of drugs to the oral cavity and tongue during inhalation, a mouthpiece that allows the tongue to be placed in a position where it is difficult for drugs to adhere during inhalation was proposed.

In addition, intraoral images were taken during inhalation, and the distance between the soft palate and the tongue, the position of the tongue, and the area of the posterior wall of the pharynx were measured to understand the effect of the mouthpiece. As a result of using the appropriate length mouthpiece, the area of the posterior wall of the pharynx was increased during inhalation, and the tongue was placed in a position where it was difficult for the drug to adhere. However, when the mouthpiece was too long, the tongue's position was not stable due to discomfort, and the area of the posterior wall of the pharynx decreased.

Removable orthodontic aligners made of polymeric materials have advantages over metal wires, which are currently the mainstream in clinical treatment of teeth array alignment, because of better aesthetics and cleanliness. However, unintentional movement of teeth occurs during the treatment using aligners. Hence, deeper understanding of the load applied to teeth from the aligner is required. In the authors’ previous study, the strain distribution in polyester aligner when mounted on misaligned teeth was measured with the help of DIC (digital image correlation) technique, and it was found out that the strain recovery plays an important role in the treatment, which leads to the driving force to move the teeth. In this study, the strain was measured including the thermoforming process, and the strain recovery was investigated by comparing the strains in two situations with teeth misalignment and without misalignment after treatment. Since DIC is not applicable to the strain measurement during compression molding, large deformation of a 2 mm square grid printed on the polyester sheet was tracked for the calculation of deformation gradient tensor and stretch tensor. The strain was increased when the aligner was mounted on a misaligned tooth, but was recovered when it moved to a correct position.

Embrittlement of human skin due to aging causes pathological problems such as skin tears, and it is desired to establish evaluation methods for solving problems related to it. Therefore, in this report, a result to evaluate the mechanics of this embrittlement is shown by using indentation test method to simulate this embrittlement with minimal invasiveness.

We here introduce approaches, SINC-seq (single-cell integrated nuclear and cytoplasmic RNA-sequencing) and NanoSINC-seq (nanopore-based SINC-seq), that allow us to study the correlated and anti-correlated expressions between cytoplasmic and nuclear transcripts in single cells at unprecedented resolution. We have developed microfluidic approaches that enable fractionation of cytoplasmic versus nuclear RNA in single cells, leveraging microflow and electric field control in a micro/nanometer scale. Our microfluidic approaches electrically and selectively lyse plasma membranes of eukaryotic cells while retaining nuclear membranes relatively intact, electrophoretically extract cytoplasmic components, physically fractionate cytoplasmic versus nuclear molecules and organelle, and automatically output the fractionated sample to individual off-chip analyses within 5 min. We demonstrated the integration of our approaches with off-chip next-generation sequencing to dissect the dynamical processes of post-transcriptional regulation.

Microphysiological systems (MPSs) are expected that new cell-based assay technology instead of animal experiments, because of the technology of simulated body environment using human-derived cells. We have developed a proximal tubule MPS based on microfluidic technologies for assessment of nephrotoxicity in vitro. The MPS was designed to ensure convenient handling for cells observation and medium change, and comprised two chips, four reservoirs, four pumps and a control equipment. In order to evaluate drug-induced nephrotoxicity, renal proximal tubule epithelial cells (RPTECs) were cultured under static and fluidic condition in the MPS. RPTECs cultured under static and fluidic condition in the MPS formed monolayer formation for at least 3 weeks. Exposure to a nephrotoxicant, cisplatin, caused a change in cell morphology of RPTECs. After 24 hours of the exposure, the number of round-shaped cells in static culture was more than that in fluidic culture, while the number of attached RPTECs to a membrane was dramatically reduced under both static and fluidic conditions after 48 hours of exposure. This MPS will be revealed the effect of perfusion on RPTECs and play a useful role for drug discovery research by assessment experiments of culture supernatant after drug exposure.

Recently, the usage of cell spheroids and organoids has been investigated to improve the biomimicry of microphysiological systems （MPSs）. However, MPSs with cell spheroids need to be formed using conventional culture vessels, and it is difficult to make spheroids uniformly and in large quantities. In this study, we developed a novel multi-organ MPS that enables cell spheroid formation and culture by placing honeycomb microwells （HMWs） at the bottom of the culture chamber. We conducted a functional comparison with HepG2 monolayer culture and spheroids using the MPS. The results showed that the spheroids made with HMW had improved function compared to the cells culture with monolayer.

Many human diseases are related to muscles, such as ALS and muscular dystrophy. The causes of these diseases are difficult to elucidate because of the interplay of numerous body systems in human, animal, and other species. We focused on an in vitro experimental strategy that uses organoids to mimic only muscle and eliminates the effects of the complex interrelationships between organs. Our group has successfully produced muscle organoids using C2C12 cells, a type of mouse cells, and collagen gels. We have developed a system that allows time-lapse observation of skeletal muscle under an inverted microscope without removing the skeletal muscle from the well plate. By applying electrical stimulation to the muscles, a contractile force is generated and the PDMS pillars tilts. The contractile force of the skeletal muscle is evaluated from the displacement of the PDMS pillars with an inverted microscope. However, In the conventional devices, the contraction force of the muscle was calculated using the Young's modulus of PDMS, and the measurement accuracy was limited. The PDMS pillars were calibrated to realize the more accurate quantitative evaluation with novel devices. Quantitative evaluation is expected to enhance the credibility of drug efficacy evaluation and electrical stimulation results. In the future, we hope to incorporate neural organoids as a new element in the device and apply it as a neuromuscular model device.

Cryopreservation is one of the fundamental techniques to maintain the cells for bio-resources as it enables the semipermanent storage of cells. All conventional cryopreservation methods use at least one cryoprotectant agent (CPA) to suppress the generation and growth of ice crystals that damage or destroy the cell structures and/or membranes. On the other hand, any CPAs should ideally be avoided due to their cytotoxicity and potential side effects. Therefore we previously reported a novel cryopreservation method without a CPA based on ultrarapid cooling. In this method, cells were ejected as tiny droplets by inkjet cell printing. The droplets were deposited on the liquid nitrogen cooled substrate and were vitrified (i. e. water molecules were extremely stopped thermal activity as a liquid state), that enables cell cryopreservation. To achieve cell cryopreservation, theoretically, more than approximately 10⁴ °C/s cooling and its 10 times fast warming was required. In this study, we cryopreserved the cells with various cooling rates and warming rates by different substrate materials and thicknesses. Remarkably, the cryopreserved cell viabilities were dependent on substrate thermal conductivity and thermal capacities. As a result, more than approximately 10⁴ °C/ s cooling and warming achieved over 70 % cell viability. However, less than 10⁴ °C/ s warming rate dramatically decreases the viability in spite of ultrafast cooling (approximately 10⁶ °C/ s). We experimentally found that the cell viabilities were influenced by the balance between cooling rate and warming rate in cryoprotectant-free cryopreservation.

The circadian rhythm in the suprachiasmatic nucleus (SCN), the master clock of the mammals, is considered to be based on single neurons with an intrinsic circadian oscillation, which are integrated by mutual synchronization through the neural or humoral mechanism. However, it is still a matter of discussion whether only a fraction of SCN neurons in the SCN can generate intrinsic rhythms and the most of other cells are just enforced or driven by a set of oscillating neurons. In this study, circadian rhythms in intracellular Ca²⁺ were measured from a solitary SCN neuron which was physically isolated from other cells. Dispersed cells were cultured on a platform of microisland in a culture dish. Circadian Ca²⁺ rhythms were detected in solitary SCN neurons. A relatively large fraction of SCN neurons generates the intrinsic circadian oscillation without neural or humoral networks. Glial cells seem to interrupt the expression of the circadian rhythmicity of intracellular Ca²⁺ under these conditions.

In this study, a new type of dielectrophoretic (DEP) cell-separation device having a parallel-plate flow channel structure was proposed to realize high throughput cell separation. The proposed device consisting of a planar electrode on the top and a planar glass plate, on which interdigitated electrodes arrays were vacuum-deposited, at the bottom was developed to facilitate high throughput cell-separation by a 3D nonuniform AC electric field generated throughout the volume of the flow channel. Live and dead Human mammary epithelial cells were used to evaluate the device performance of separation. Flow cytometric analysis of number of separated cells was adopted to cell samples collected at the exit of the flow channel for the evaluation of the device performance. Results demonstrated that dead cells travelled through the flow channel without being trapped in the flow channel, meanwhile live cells were trapped on the edges of high-voltage electrodes. Cells were thus successfully separated with separation ratios higher than ~ 90% under the appropriately tuned field frequency and applied AC voltage.

A variety of glycoproteins and lipids are expressed and adsorbed on the surface of articular cartilage. And these molecules play an important role in the cartilage lubrication function. However, the effects of the molecular distribution and the changes in their local interactions at the cartilage contact interface on the lubrication property have not been clarified yet. In this study, we developed an optical system that can detect changes in the molecular distribution and interactions at the contact interface of tissue-engineered cartilage during friction by using surface plasmon resonance (SPR), which can detect molecular interactions near the contact surface. By using a variable laser incidence angle mechanism, it is possible to scan the resonance angle, which changes with molecular species and interactions during friction. In this study, we evalulated the lubrication properties of agarose gel and agarose-chondrocyte complex material with observing the contact interface using the optical system. In the comparison of the contact state at the agarose specific incidence angle, it was confirmed that the region of SPR at the contact interface of the agarose-chondrocyte complex material clearly decreased. As a result, we can successfully detect the time-dependent changes in the relation between the contact state and the lubrication property of tissue-engineered cartilate tissue.

We developed a microfluidic device by stacking plastic films at intervals of 20 μm using a press process and utilizing the gaps between the films. In this study, we evaluated the interaction between the surface of the device and serum components in order to apply the device to dengue fever diagnosis by ELISA. In this study, we evaluated the interaction between the device surface and serum components for the application to dengue diagnosis by ELISA. Therefore, the antibodies were covalently coupled to the device surface by EDC/NHS coupling to prevent detachment. The surface-modified device succeeded in detecting serum in less than half the time of the conventional method.

Recently, as increase of food demand due to the population growth, aeroponic cultivation system, which has higher production efficiency than other cultivation systems, has attracted great attention. Although potato is one of the vegetables expected to be mass-produced due to its richness in nutrition, it is difficult to cultivate them by conventional aeroponics systems where the products are not physically supported. In order to develop an aeroponic system to cultivate potatoes, development of a cultivation medium to support seeds and baby potatoes without any hindrance to nutrient supply is required. In this study, we applied lattice-structured mediums to aeroponic cultivation of potatoes. The result of a cultivation test in which potatoes were cultivated with spraying hydroponic method using lattice-structured mediums demonstrated that supporting potatoes by lattice-structured mediums promotes growth of potatoes and increases harvest weight of tubers. Moreover, for harvesting potatoes efficiently without any damages, we developed a novel 3D gel printer enabling fabrication of gel-based cultivation mediums. The fabrication tests of the 3D gel printer led to determine the optimal air pressure of extruding gels and CaCl₂ concentration of sol support bath, which are 0.30 MPa and 0.30 mmol/L, respectively.

Because the micro/nano-scale structures of the living things have various functions, the micro/nano-scale structures have been attracting a lot of attention. In some terrestrial organisms, nano-scale structure (nipple-array) is considered to act as the self-cleaning surface by reducing adhesion force. Some aquatic organisms, such as ascidians, also have nipple array on their body surface, but few studies measure the adhesion force of the nipple-arrays in a submerged environment like the sea. Therefore, we aim to measure the adhesion force of the nipple-array in water, in order to evaluate the functional properties of the nano-structures on the ascidian surface and to consider their biomimetic applications. In this study, for simplifying, we measured the adhesion force of a synthetic nipple array, MOSMITE^TM, and a flat surface. The adhesion force was measured with an atomic force microscope and the measurements were carried out in the water. The adhesion force of the MOSMITE^TM (1.3 ± 0.3 nN) was smaller than that of the flat (4.6 ± 0.4 nN). These results indicate that the nipple-array reduces the adhesion force more in the water compared with the flat surface.

A magnetic fluid is a fluid with magnetic properties. The magnetic fluid is made by mixing a dispersant with a base liquid and dispersing a ferromagnetic material to the nanoparticle level in the liquid. These magnetic fluids are widely used in the fields of engineering and medicine. However, conventional magnetic fluid production methods are complicated and take a long time. Therefore, a simpler method of dispersing particles in liquid is required. In this study, we clarified the condition to generate plasma in liquid. Moreover, we developed a production method of liquid with dispersed particles by using the characteristics of nanoparticle generation in liquid plasma. The results showed that the breakdown voltage was decreased slightly as the distance between the electrodes increased. The breakdown voltage tended to decrease as the pulse width increased. Small black particles were dispersed in the upper liquid. We have concluded that these particles are ferromagnetic nickel particles.

This paper reports a frequency modulated (FM) Lorentz force MEMS magnetometer using superposed clockwise (CW) and counter clockwise (CCW) modes on a quad mass resonator. Sensing currents synchronous to both modes modulate the modal stiffnesses, eventually resonant frequencies. The current directions correspond to both modes have same amplitudes but opposite direction, thus the frequency difference between CW and CCW modes could be generated. In this paper, the principle of operation was confirmed by the numerical simulation. The estimated sensitivity was 7.87 Hz/mT.

In this paper, it is reviewed that combinatorial technologies for the fabrication and characterization of a large number of samples at once, the use of MEMS and other microfabrication technologies for the characterization of the samples, and our efforts to use machine learning to analyze and improve the search efficiency of the large number of sample data obtained by the combinatorial technologies. We introduce combinatorial arc plasma deposition, which enables the combinatorial deposition of amorphous alloy materials. The composition-graded films fabricated by this method are separated and labeled into thin-film libraries by using microfabrication methods, and their properties are evaluated using MEMS structures. As an example of material search with the aid of machine learning, we describe the identification of physical properties with high contribution to the current density of electrocatalysts by random forest analysis, the examination of search termination conditions by Bayesian optimization, and the estimation of crystal grain size of magnetic materials from Barkhausen noise by machine learning.

It is known that when a surfactant or a water-soluble polymer is added to water, the fluid becomes viscoelastic and the turbulent frictional drag due is significantly reduced by the Toms effect. In this report, I will introduce examples of practical research and basic study on the Toms effect. In the practical research aiming at energy saving, the case of the building air conditioning system using the surfactant and the case of the ship using the ship hull paint were introduced. In a basic study simulating the use of ship hull paint containing water soluble polymer, it was clarified that the polymer supplied from the wall surface strongly affects the coherent structure of wall turbulence, suppresses Reynolds shear stress, and reduces wall friction resistance.

The results of investigation for the relation between fuel/air mixture formation in near-field of Diesel spray flame and combustion characteristics, and those of investigation for the heat transfer in Diesel combustion are reported. The rapid compression machine coupled with special designed combustion chambers is use for these investigations. Obtained results show that the mixture formation in the near-field of spray affects strongly the emissions from Diesel combustion, and that the heat transfer of Diesel combustion can’t be described by the conventional heat transfer models which are based on the heat transfer in steady impinging single phase jets.

A vehicle driven by an internal-combustion engine is being shifted to an electric vehicle in recent years. A transmission (reduction gear) is also used for the electric vehicle because the driving motor is effectively used at high speed, and a small size and weight saving are desired than the past. Therefore, gears, main elements of a vehicle transmission, are required higher durability, and the study on the gear strength is of practical importance to develop a high performance transmission with high reliability. Considering these circumstances, the author has carried out the research and development on improving the reliability of the transmission gears. The tooth surface strength of the gears has been increased by using latest material, heat treatment and surface treatment. The gear design technology has been improved to clarify the influence of the tooth surface deviation and the lubricating conditions on the tooth surface strength. Recently, the author has also conducted the research on the prediction of residual surface fatigue life of the gears using X-ray diffraction method. Some of the results are introduced in this paper.

This paper intrdouces an electro-conjugate fluid (ECF) micropump whose pumping sources are fabricated by MEMS technology and mounted on the inside of fluidic channels. ECF is a kind of functional and dielectric fluid. A strong and active jet flow of ECF is generated between electrodes surrounded by ECF, when high DC voltage is applied to the electrodes. Our ECF micropump consists of triangular prism and slit electrode pairs (TPSEs), which can be fabricated by the MEMS technology based on the micromolding of a thick photoresist followed by the electroforming. The experimental results prove that the MEMS-fabricated ECF micropump can be a good candidate as a microhydraulic pressure source for various microactuator systems. The paper also introduces the integration of TPSEs for higher output power. Thanks to the modular design of a TPSE, the output pressure and flow rate of the ECF micropumps are increased by only integrating TPSEs in series and parallel, respectively. In addition to this 2D integration of TPSEs, this paper describes the multilayer fabrication, which is the 3D integration of TPSEs to realize high-aspect-ratio TPSEs. These proposed MEMS-fabricated ECF micropumps as microhydraulic power sources have been applied for various applications, such as soft robots, focus-tunable microlens, droplet-based lab-on-a-chip devices, and so on.

Hayabusa2, the 2nd Japanese asteroid explorer and sample return mission, has successfully brought samples of the C-type, Near-earth asteroid Ryugu back to the Earth on December 6, 2020. Hayabusa2 achieved a lot of outstanding missions, such as revealing the characteristics of Ryugu as a top-shaped, rubble pile asteroid, sampling from two different points on the surface of Ryugu, and making an artificial impact crater on Ryugu. The artificial crater was produced with the Small Carry-on Impactor (SCI) and as large as that formed in the gravity-controlled regime, in which the crater scale is determined not by the target strength, but by the target gravity. The crater formation in the gravity-controlled regime was also confirmed with the images of impact ejecta taken by Deployable Camera 3 (DCAM3). This is the most important result obtained by the first impact experiment on a real asteroid, suggesting that the surface strength of Ryugu is as small as that of sand. Other scientific results obtained from the SCI operation are also introduced in this paper to show the utility of impactors in planetary explorations.

In this paper, micro stereolithography techniques are reviewed. A multi-material micro stereolithography system based on single-photon polymerization using multiple droplets is introduced as a novel method to create heterogeneous structures such as multicolor structures. Additionally, 3D-printed micromachines such as optically driven micropumps and topology optimized microtweezers are shown. The multi-material micro stereolithography will be useful for producing functional microdevices including microfluidic devices, micromachines and scaffolds.

Osteocytes modulate osteoclasts for bone resorption and osteoblasts for bone formation during the bone remodeling process. In this study, we elucidated the effect of 3D culture on the osteocyte differentiation. We fabricated self-organized spheroids reconstructed by mouse pre-osteoblast cells. The cells in 3D tissue-engineered model rendered the osteocyte-likeness within 2 days. We also showed that the cell condensed condition achieved from the 3D culture is essential for up-regulations of osteocyte gene expressions. Moreover, compared to the conventional monolayer model, the 3D culture model exhibited a different response to external stimuli such as hypoxia. In this study, we broadened a new insight into the osteocyte differentiation capability of pre-osteoblast cells using the 3D culture model.

Vascular cell senescence and aging are known to be associated with serious vascular diseases, such as arteriosclerosis and aneurysm generation. However, it is unclear how cellular dedifferentiation and senescence affects cellular contractile force which is especially important for vascular smooth muscle cells. Here we investigated the changes in the cellular contractile ability during repeatedly passage-cultivation that promotes cell dedifferentiation and senescence. Porcine aortic vascular smooth muscle cells exposed to several passage-cultivation were seeded on the PDMS elastic micropillar array substrates, and their contractile forces were estimated by the deflection of the pillars. Furthermore, we dissected actin stress fibers in living cells by laser irradiation to release their pretension, observed the dynamic behavior of the dissected fibers, and estimated the internal tension of individual stress fibers. We found that the both of the whole cell contractile forces and the internal tension of individual stress fibers were significantly decreased in cell dedifferentiation and senescence induced by repeatedly passage-cultivation, and the decrease was more sensitive in the individual stress fibers than in the whole cell. These results indicate that cellular contractile forces are deeply involved in cellular dedifferentiation and senescence.

Mechanical properties of cancer cells are important for considering the behavior of cancer cells. However, few studies evaluate the mechanical properties and adhesion force of whole cells at the same moment. In this study, we evaluated stiffness and adhesion force of cancer cells (HeLa) by using an in-process micro tensile tester which we developed. To analyze the effect of the microtubule on the mechanical property and the adhesion force of cells, we carried out the tensile test to treated cells with colchicine which inhibits polymerization of the microtubule. As a result, the upper stiffness of treated cells (14.2 ± 7.1 nN/%strain) was larger than that of control cells (5.6 ± 3.5 nN/%strain). Additionally, the adhesion force of treated cells (472.7 ± 278.5 nN) was also larger than that of control cells (182.2 ± 94.0 nN).

In order to visualize forces at molecular level, several tension sensors have been developed based on Förster resonance energy transfer (FRET) and applied in cultured cells. Recently, transgenic mice expressing a tension sensor were also developed to visualize forces at tissue level. However, their fluorescence was so weak that a high-cost FLIM (Fluorescence Lifetime Imaging) system was necessary for observation. Furthermore, the fluorescent protein pair adopted in the sensor cannot be observed with widely-used 488 nm laser system. In a previous study, we developed an actinin tension sensor by inserting a FRET cassette sstFRET-GR into actinin. This sensor can be observed with the 488 nm laser system. In this study, we introduced the gene of this sensor engineered with the Cre/loxP system into the ROSA26 locus of the C57BL/6N mice, and crossbred them with Cre mice to obtain mice expressing the tension sensor. We excised various tissues from them including aorta, heart, tendon, skin, diaphragm, and intestine, and isolated cells from each tissue. The fluorescence was so bright that the change in FRET ratio was observable with a general confocal microscope for all tissues and cells. We performed tensile tests of these tissues and cells, and confirmed that the sensor is working properly. The ratio of FRET ratio change to unit tensile strain was almost similar among tissues, however it is smaller than that in their cells. The present FRET mice may become a powerful tool in mechanobiology of cells and tissues.

In recent high-efficiency gas turbine combined cycle (GTCC) systems, thermal barrier coatings (TBCs) are indispensable for turbine blades due to the high temperature of the working combustion gas. Generally, the top coat (TC) of TBCs is deposited by atmospheric plasma spraying (APS) and electron beam physical vapor deposition (EB-PVD). On the other hand, the suspension plasma spraying (SPS) method, which enables microstructure control by using fine sprayed particles, has been studied for TBCs, because TC deposited by SPS have cauliflower-like columnar microstructure and are expected to have high thermal stress relaxation. In this study, we evaluated the thermal cycling characteristics of TBCs with different microstructures prepared by varying the column diameter of SPS. It reveals from the experimental results that the composite oxide growth, which causes a decrease in the thermal fatigue life, and the delamination crack propagation from the edge of interface are suppressed with decreasing the column diameter.

An advanced thermal barrier coating is demanded for achieving the next generation gas turbine with a high efficiency. As one of many candidates, RTa₃O₉ attracts attention owing to the low thermal conductivity. In this study, the mechanical properties of YbTa₃O₉ were evaluated. As the results, it was shown that YbTa₃O₉ exhibited significantly lower thermal conductivity. However, thermal conductivities of YbTa₃O₉ exposed at more than 1073 K were increased up to that of YSZ.

Tungsten carbide (WC) materials, normally constructed by combination of WC and Co as binder phase, are widely used for cemented carbide cutting tools. Whereas the problem to form brittle phases due to the production process was reported on WC-Co coatings fabricated by thermal spraying.

The authors have shown that WC-Ni hard coatings can be formed by a combined wet plating and gas carburizing method instead of thermal spraying. However, the mechanism of WC formation in this process and the effect of microstructure on mechanical properties are still unclear. In this study, specimens were prepared by using a combined wet plating and gas carburizing method under different process conditions. Various analyses, observations, and mechanical property evaluations were carried out on those specimens.

In cold spraying，a rectangular cross-sectional nozzle can produce a wider range of coatings than a circular cross-sectional nozzle，which is expected to improve the work efficiency. In previous studies，aluminum coatings were fabricated and relatively flat coating patterns were obtained. In this study，we verified whether there was any variation in the adhesion strength within the coating. A high-pressure cold spray apparatus was used for the experiment，and pure aluminum spherical powder was fed in the axial direction. After that，the adhesion strength at the center and edge of the coating was measured using a thin-coating adhesion strength measurement device，and the cross section and single particles of the coating were observed using a scanning electron microscope. As a result，it was confirmed that the adhesion strength was uniform between the center and the edge of the aluminum coating.

Additive manufacturing (AM) is a rapidly developing technology. One of the main AM technologies is the use of thermal energy, such as lasers, to melt and deposit metal powder materials. This AM can form multilayer structures, but may cause abnormal melting of some materials. On the other hand, cold spray additive manufacturing (CSAM), has advantages such as the ability to form metal particles without melting them and high processing speed. However, it has some problems such as large forming patterns and triangular cross-section of layers. In our laboratory, as a part of AM, we tried to form thin copper layers of several millimeter width by CS. In this experiment, in order to obtain basic data for CSAM using a nozzle with a rectangular cross-section, we attempted thin wall forming of copper with a height of 20 mm using a rectangular cross section nozzle, observed the cross-section of the formed object, and compared it with that using a circular cross section nozzle.

The interest of polymer coating by cold spray process lies in the speed of the process, which requires less energy than the conventional manufacturing methods. However, the deposition efficiency and adhesion strength of polymer particles on a metallic substrate are usually very low. In our previous study, Ravi et al. (Ravi et al., Surface and Coatings Technology, 2019) cold sprayed Perfluoro alkoxy alkane (PFA) powder mixed with 5% of Fumed Nano-Alumina (FNA) on a metallic substrate. A super-hydrophobic fluoropolymer coating was manufactured with, however, low deposition efficiency. In this study, different methods were analyzed in an attempt to increase the deposition efficiency of the polymer feedstock on a metallic substrate. First, the substrate surface was laser-textured before spraying, increasing the deposition efficiency to 45%. Then, to further enhance the deposition efficiency, a metallic bond coat, consisting of Ti or Cu particles, was introduced as an intermediate layer between the substrate and the polymer coating. The deposition efficiency reached 81.4% while spraying the PFA-FNA feedstock on the Ti bond coat. Thus, the surface roughness plays a key role in the significant amelioration of the polymer particle deposition on a metallic substrate by promoting mechanical interlocking. Finally, by increasing the power output of the homogenizer used to mix PFA and FNA, 96% deposition efficiency was achieved. This new record shows that other factors, such as chemical interactions between PFA, FNA, and the metallic substrate, are also significant factors influencing the deposition of polymer powder.

Substrate pre-treatment using pulsed laser ablation has been reported as one of the attractive techniques to improve the deposition efficiency and bonding strength of a metal coating fabricated by low pressure cold spraying. In this study, the effect of laser treatment on the deposition efficiency was examined for copper coatings on pre-oxidized copper substrates under different oxidation temperatures. Nd:YAG laser was applied to the oxidized substrates to remove the surface oxide film. The result shows that the laser treatment has little effect on the copper deposition efficiency on the copper substrate oxidized under 200 degrees Celsius. The deposition efficiency for the first cold spray traverse decreases significantly on the substrates oxidized under 400 degrees Celsius and the coating delamination was observed during the cold spraying. This lower deposition efficiency and coating adhesion strength can be attributed to the substrate softening by an annealing effect and substrate re-oxidation by the laser treatment which prevents particles from adhering to the substrate.

In this study, TiO₂ photocatalyst balls were prepared by sulfuric and acetic acid bath treatment and subsequent heat oxidation. The photocatalytic activity was investigated and discussed relating the conditions (temperature, concentration and time) of the acid bath. TiO₂ photocatalyst with anatase type was obtained by the acid bath treatment and subsequent heat oxidation. The photocatalytic activity reached R = 10.3 nmol・L^-1・min^-1 for the sample by the sulfuric acid treatment with concentration of 0.25 mol/L at 393 K for 60 min. The influence of the formation of anatase type TiO₂, the corrosion in the acid bath treatment and the microstructures of the surface of TiO₂ photocatalyst balls on the photocatalytic activity was discussed.

In this study, TiO₂ nanotube arrays were prepared by anodization. The diameter and length of the TiO₂ nanotubes were measured. The influence of the applied voltage, distance between the electrodes, addition amount of NH₄F on TiO₂ nanotube arrays were discussed. The photocatalytic activity was investigated. The diameter increases with increasing of applied voltage with a liner relationship. The length increases with applied voltage, and has an exponential relationship. The moving of the ions and reactions in the anodization were discussed. The TiO₂ nanotube arrays had high photocatalytic activity.

The purpose of this study is to improve the durability of the downflow hanging sponge reactor—a simple trickling filter system used for purifying water, with an ultimate aim of increasing its water purification capacity. To this end, we have developed a technology to coat the cell wall surface of an open-cell Ni foam with antibacterial Ag zeolite powder, using polyethylene (PE) powder as a binder for the adhesion of the zeolite powder to the cell wall surface. At first, the open-cell type Ni foam was prepared by powder metallurgy using urethane foam as a template, and a mixture of the Ag zeolite and PE powders was prepared using a ball mill. The prepared Ni foam was immersed in an adhesive liquid and then dried completely, following which the mixture of Ag zeolite and PE powders was attached to its cell wall surface by the dipcoating method. Subsequently, heat treatment was used to achieve the adherence of the Ag zeolite powder to the cell wall surface of the Ni foam via PE. Adhesion of the Ag zeolite powder to the cell wall surface of the Ni foam was visually confirmed using a digital camera, a desktop electron microscope viz. “TM-1000” miniscope, and a field emission scanning electron microscope. Therefrom it was observed that when the heat treatment temperatures were 423 K and 433 K, the PE powder retained its spherical shape, and the cubical Ag zeolite was attached to its surface. However, when the heat treatment temperatures were 443 K and 473 K, the spherical PE powder was found to have melted and solidified into a smooth layer, and the Ag zeolite powder was found to be incorporated inside, as well as on the surface, of the PE layer.

In order to improve the fatigue strength of various metal materials, we have developed a surface treatment called cutting and rubbing process. In this report, the test material is high-strength ductile cast iron. Although this is a high-strength material, it has many defects that can cause cracks in fatigue tests. Fatigue tests were carried out at room temperature using a rotating bending fatigue machine operating at 50 Hz. The fatigue life of the cutting and rubbing processed specimen was much longer than that of non-surface treated specimens. Regarding the fatigue strength at 10⁷ cycles, no enhancement due to the present surface processing was attained, because of the fish-eye fracture. The fracture was caused by cracks from defects beneath the processed layer. The compressive residual stresses of the cutting and rubbing processed specimen surface measured by X-ray diffraction was 441MPa. The stress constant used in this measurement was -340 MPa / degree.

The purpose of this study was to clarify the skill of expert from the relationship between the hammering sound and the hammering position. The hammering sound during the sheet metal work was recorded and the three-dimensional behavior of the hammer movement was measured. The incremental change in the amplitude of the hammering sound was smaller in the expert than in the non-expert. There was no relation between the amplitude value of the hammering sound and the hammering position, which is common among experts.

Sheet metal in automotive repair is the process of restoring a deformed body to its original shape using various tools. This work relies on human skills, there are individual differences in skill levels, and it takes a lot of time to learn. The purpose of this study is to support the smooth acquisition of skills in sheet metal repair work. In this paper, we focus on the handling of the tools used in sheet metal work, which are dollys and hammers. The relationship between the force of gripping a tool and the movement of a hammer during work was examined to elucidate the skills of expert workers. As a result, the experts found that the hammer moved an almost constant distances and the gripping force did not change much during the work. But non-experts, the gripping force were not constant, they had changed a lot during the work.

In order to examine the impression of grape juice, sensory evaluation was carried out using two kinds of Kairagi with different sintered temperatures. From the result of SD profile and factor analysis, it was made to feel that "Kiwami" in which the sintered temperature was high was not sweet, and there was no stimulation, and it was difficult to be familiar, and it did not remain in the impression. It was made to feel that "Nagomi" in which the sintered temperature was low was sweet, stimulating, familiar, and remained in the impression.

In recent years, digitalization has been rapidly progressing in the field of industrial manufacturing. In this study, we investigate the application of this technology to the production of replicas, which are often used in museum exhibits. We aim to create more effective cross-modalities by not only producing full-size replicas but also using different scales or partially extracted replicas for hands-on exhibits, taking advantage of the ease of scale change that is an advantage of digital data. As a first step, we acquired the shape data of the object to be evaluated using a handy 3D scanner, converted it into 3D-CAD data, and fabricated it in high-definition full-color at various magnifications. As a result of discussing the effect of this method, the effectiveness of the proposed method was indicated.