ABSTRACT. Detached breakwaters, commonly used to mitigate coastal erosion, can lead to significant sedimentation issues when employed as protective structures near ports. These issues often result in tombolo formation, which can severely disrupt port operations. This study examines a case at a port in southern Java, where the use of a detached breakwater caused a complete operational shutdown. Through simulations conducted with GenCade, the sedimentation process was modelled to identify the conditions leading to tombolo formation. Based on these findings, alternative design solutions are proposed to prevent similar problems in the future. The results highlight the need to avoid the use of detached breakwaters for port protection, emphasising that this approach represents a fundamental error in coastal engineering. More suitable coastal structures should be encouraged to ensure the effectiveness of port operations.

ABSTRACT. In the initial stage of research on the physical modeling of gabion-type breakwater stability, preliminary experiments on simulated wave generation in various variations of wave deviation and variations in water depth in the wave channel in the laboratory have been carried out. The purpose of this research is to understand the wave characteristic model that will be used in the simulation of the gabion-type breakwater physical model. The research was conducted on a regular wave channel of tilting flume type with 15 m length, 30 cm width, and 45 cm glass wall height. The regular wave flume is equipped with an adjustable stroke and variator to obtain variations in wave height and period. Wave generation simulation was conducted with stroke variations (St) of 7 cm, 8 cm and 9 cm, while variations for wave period (T) were 1 second, 1.1 second and 1.2 second and water depth (d) was 20 cm, 25 cm and 30 cm. The generated wave height was recorded with a data logger through 3 wave probes placed at the base, centre and end of the flume. Data logger calibration was performed to convert the generated voltage unit into length unit. The relative depth (d/L) that can be applied in this flume is 0.05 - 0.25 which has similarities with the transition sea model according to the prototype placement plan in the field. The experimental results show that the larger the value of (d/L) 0.132-0.219), the smaller the wave reflection (Kr = 0.070 - 0.246).

ABSTRACT. Scour, erosion, and sedimentation problems have a significant impact on river channels, especially on the Ogan River in the Ogan Ilir Regency. This study aims to determine the characteristics of the Ogan River and conduct a literature review related to river meander stabilization. The method used is descriptive qualitative, where the results of research and analysis are described in the form of scientific narratives. From this analysis, a conclusion is drawn about the interaction between various factors that affect river stability. The results showed that the physical characteristics of the Ogan River play an important role in forming sediment transport zones and influence the shape of river morphology. These characteristics include flow velocity, sediment particle size and distribution, and meander configuration. The literature review highlights the importance of understanding the interactions between sediment transport, flow dynamics, and channel morphology to develop effective meander stabilization strategies. The study concluded that river meander stabilization strategies should consider the specific conditions of local river characteristics. An integrative approach is needed to effectively address the problems of scour, erosion, and sedimentation, thereby minimizing negative impacts on the surrounding environment. As such, this research not only provides a better understanding of the characteristics and dynamics of the Ogan river but also offers valuable insights for more holistic and sustainable river management. Through this study, it is hoped that practical and implementable steps can be taken to address river problems, which will support the welfare of communities that depend on the sustainability of river ecosystems. By considering the results of this study, policymakers and stakeholders can design more targeted and efficient interventions to maintain the stability and ecological function of the Ogan River.

ABSTRACT. The opening of the Skyline Rail System in Honolulu in 2023 was a significant milestone towards improving mobility and balancing housing development towards the leeward (western) side of the island from the urban core. The urban core and the Waikiki special district have long served as the primary destination for residents and visitors, encompassing a high density of work, healthcare, and tourism activity locations. However, residents and visitors pay the price of paradise with respect to housing prices within and near the urban core, in addition to battling daily gridlock congestion on the H1, H3, and other main arterials during peak hours. This study investigates the relationship between improved first/last mile access to the Skyline System through better bus transit coordination and workplace incentives for informal transportation services, such as work vanpools and ad hoc carpooling. We evaluate these through POLARIS, a transportation and activity agent-based simulator, to evaluate these service improvements at the network level. Specific first/last mile transit scenarios examined include:

A) Improved coordination with TheBus, including anticipated BRT services from Millilani and other inner island origins to the Skyline Rail System;

B) Travel mode shifts towards informal transportation services, due to workplace incentives and other similar mechanisms.

In addition to changes in the level-of-service (LOS), such as travel times and costs, we also investigate improvements behavioral metrics related to traveler activity schedule execution and workloads. These include activity start times and the level of adjustments between the planned and executed activity schedules of travelers.

ABSTRACT. Background: Prostate cancer is the second most prevalent cancer type among men. According to the American Cancer Society, about 1 in 8 men will be diagnosed with prostate cancer in their lifetime. High-dose-rate (HDR) brachytherapy (BT) has been acknowledged as a widely utilized treatment for patients with intermediate- and high-risk prostate cancer, despite its side-effects such as edema, incontinence, and impotence. Recently we have presented a new curvilinear catheter implantation (CuLCI) technique for needle implantation in prostate HDR BT procedure, as an alternative to conventional rectilinear catheter implantation (ReLCI). The CuLCI method enables curved needle implantation, conforming to the shape of the prostate, offering opportunities to improve dosimetric coverage utilizing reduced number of needles. This work introduces a 7-degrees-of-freedom (DOF) MRI-conditional piezoelectrically actuated robotic system to enable CuLCI inside MRI bore using excellent MR imaging feedback. Methods: The robot was designed with three main modules of (i) a manual positioning stage, (ii) a robotically controlled Scott-Russell scissor mechanism, and (iii) an active needle manipulation system; and fabricated with MRI-compatible materials, piezoelectric rotary and linear actuators (from PiezoMotion and PiezoMotor, respectively), and MRI safe sensors (from Micronor Sensors). A fiducial frame comprising seven tubes filled with visible high contrast fluid (from Beekley) was designed and installed on the robot to enable registration within the MR environment. Kinematics of the robot and the active needle bending were developed for accurate needle manipulation in a desired trajectory using a closed-loop disturbance observer PID controller. Results: It was shown that the controller can steer the needle to realize reference sine and triangular bending angles with an accuracy of 1.78 and 1.88 degrees, respectively in air. The trajectory tracking capability of the system in free space is shown with an RMS error of 0.86mm and a standard deviation of 0.36mm. The robot's capability to steer the needle towards target inside a phantom tissue was presented. Three trajectories were followed via a teleoperative control for the active needle to reach assigned targets inside the phantom. Visual tracking was used to capture the needle curvatures. Conclusion: This work presents the first of its kind MRI-conditional robot aimed for curvilinear implementation inside the prostate gland. It was shown that the active needle is capable of being effectively controlled in a phantom tissue using our robotic platform. Future work will examine the performance of the robot inside an MRI bore and evaluate the robot’s capabilities in targeting multiple points inside a soft phantom tissue under closed-loop MRI guidance.

ABSTRACT. For companies, adhering to industry standards, regulations, and laws is essential. This includes the requirement to file annual financial statements using accounting standards issued by relevant government agencies. However, companies often document their transactions with various non-standard descriptions, leading to discrepancies between these transactions and the accounting standards. This project aims to address these discrepancies by proposing an automated tool that uses Artificial Intelligence (AI) and Machine Learning (ML) models to align company transactions with accounting standards. Eleven AI/ML models, including Random Forest (RF) and Decision Tree Classifier (DTC), were developed and trained using historical transactions. The evaluation results indicate that while both RF and DTC models have identical training accuracies, RF performs slightly better on the test set. Consequently, RF was chosen for the automated tool.

ABSTRACT. This paper considers the problem of seed point detection and contour extraction from images of multiple partially overlapping pill bugs. The extraction is based on the method by Zafari et al., which links seed points—critical information for segmenting overlapping objects—to the edges of the contours and fits ellipses to them. Typically, seed points are obtained by binarizing the image and using morphological transformations and radial symmetry transformations, but this approach may not work well when multiple pill bugs are present as a cluster. To solve this issue, we propose a method that employs the deep learning technique U-Net to determine seed points. Also, we develop a method for artificially creating a dataset to train U-Net based on observations of the collective movement of pill bugs. The usefulness of these methods is demonstrated through experiments.

ABSTRACT. This research aims to develop a driver model to quantitatively evaluate the risk of a driver's driving behavior. Conventional driver models have been built based on a deterministic approach, relying on simple parameters such as driver reaction time. These models simulated driving behavior based on predefined rules and scenarios, and it was difficult to adequately reflect dynamic changes in the actual driving environment and individual driver characteristics. In this study, a driver model was developed using reinforcement learning and incorporating the driver's visual field information to simulate more realistic driving behavior. Since visual field information accounts for more than 90% of the information acquired in driving, incorporating visual information into the model is extremely important for increasing the reality of driving behavior. The developed driver model was used to assess the risk in a right-turn scenario, specifically evaluating the likelihood of collisions (probability of collision) and the severity of collisions (pre-crash kinetic energy). Parameters such as the frequency of pedestrians, walking speed and the behavior of oncoming vehicles were set based on probability distributions and Monte Carlo simulations were conducted. This enabled the quantitative assessment of collision risk during right-turns under different conditions. In the future, it is expected that the driver model created by this method will be used to conduct simulations in various scenarios to evaluate various aspects of driver behavior in more detail and to contribute to more effective road safety measures.

ABSTRACT. Porous materials with nanospaces, such as zeolites, activated carbons, and silica gels, hold promise for various applications across fields including environment, energy, optics, medicine, and electronics. Mesoporous materials including MCM series synthesized using amphiphilic molecules have been actively researched worldwide, resulting in thousands of publications annually and indicating the maturity of this field. While coordination nanospaces, such as those found in metal-organic frameworks (MOFs), have seen rapid acceleration in research, their applications remain primarily limited to gas adsorption, separation, and molecular recognition. However, to address global energy challenges, such as (electro)catalysts, supercapacitors, secondary batteries, and fuel cells, the discovery of novel porous materials composed of “stable and conductive inorganic solids” linked by covalent or metal bonds is essential.

In the past decades, our group has focused on the phenomenon of “self-organization”, leveraging interactions between molecules to introduce numerous conductive inorganic frameworks into porous systems. This breakthrough has significantly advanced the field of porous materials. Notably, nano/mesoporous metals discovered by Yamauchi et al. show promise for various applications due to their metallic frameworks, offering high specific surface areas effective for enhancing chemical reactions and acting as nanocatalysts. Additionally, nanoporous metals exhibit excellent activity in (electro)chemical reactions due to their electrochemical and catalytic activities.

Currently, Yamauchi’s group is expanding this concept to other nanoporous systems with diverse compositions (e.g., carbons, chalcogenides, metal sulfides, etc.). Recently, our group discovered a controlled assembly of micelles utilizing effective coordination interactions between inorganic species and micelle surfaces, resulting in novel 0D, 1D, and 2D nanomaterials with internal nanospaces. Today, we will present our progress in the second generation of porous materials.

ABSTRACT. Cement-based piezoelectric composites (PECs) are sensors that can be used for structural health monitoring (SHM) due to their excellent compatibility with cementitious structures. To develop PECs with better polarization and enhanced piezoelectric properties, it is essential to increase their piezoelectricity by adjusting the manufacturing process or adding appropriate materials. Experiments showed that the presence of free water inside the specimen can significantly affect the polarization difficulty and piezoelectricity of PEC. This study explores the effect of free water on polarization and piezoelectricity during the manufacturing process. PEC uses cement as the matrix and lead zirconate titanate (PZT) as inclusions (each accounting for 50 vol.%). Employing vacuum drying, ethanol dehydration, and heat treatment reduces the free water content in cement specimens. Relative permittivity, dielectric loss, and resistivity are measures of the ease of polarization. Experimental results show that reducing the free water content of PEC specimens through vacuum drying, ethanol dehydration, and heat treatment during the manufacturing process can enhance PEC performance. PEC specimens with high free water content increase the difficulties of specimens in poling. The piezoelectric voltage constant (g33) of PEC exceeds 20 mV-m/N when the free water content is reduced. PEC sensors have monitoring capabilities similar to those of PZT sensors.

ABSTRACT. Dielectric elastomers (DEs) have garnered significant attention as power generation materials due to their exceptional elasticity, response speed, and high energy density capabilities. Dielectric elastomer generators (DEG), which convert mechanical energy into electrical energy, operate fundamentally on the principle of capacitance changes within DE. Although acrylic DEs have been extensively studied for their high permittivity and large deformation capacity (low module and high elongation at break), their low durability has been a persistent challenge. This study aims to enhance the performance of DEG by incorporating titanium dioxide (TiO2) particles into silicone-based DE, known for their superior durability. We evaluate the changes in dielectric properties and power generation performance of the silicone-based DE with different amount of TiO2 particles to determine the optimal concentration. Specifically, we measured the permittivity and power generation performance of silicone-based DE filled with TiO2 particles with addition percentage of 0 vol%, 2.5 vol%, and 5.0 vol%. Our findings indicate that filling silicone-based DE with larger amount of TiO2 particles results in improved permittivity. However, the power generation performance did not exhibit a monotonous improvement with increasing amount of TiO2 particles. This phenomenon was analyzed in the context of tensile and viscoelastic properties. Furthermore, the impact of loading speed on power generation was investigated. Results showed that increasing the loading speed generally maintained or enhanced the power generation properties of certain silicone-based DE. Nonetheless, power generation performance tended to decrease with increasing loading speed for silicone-based DE filled with large amount of TiO2 particles. These findings suggest that both loading speed and material dielectric properties are critical factors in DEG design and material selection, influencing the overall power generation performance.

ABSTRACT. This work focuses on diluted magnetic semiconductors (DMS), a kind of compound semiconductor doped by magnetic ions, which has both magnetic and semiconductive characteristics, and novel electrical, optical and magnetic properties are expected for such materials, which leads to new electronic devices and open up new semiconductor technology. Such materials are formed after some atoms in a non-magnetic semiconductor are replaced by magnetic ions (transition element and rare-earth element ions). This work investigates AlN thin films doped with Mn ions (AlMnN). AlN is chosen for its wide applications in electronic, optoelectronic and field emission devices due to its high thermal conductivity, superior mechanical strength, excellent thermal and chemical stability and low dielectric constant, alongside its largest and modifiable band gap ranging from UV to infrared wavelengths through dopants. Moreover, doping can improve electronic properties of AlN by increasing the number of carriers. The replacement of Al atoms with Mn in AlN aims to confirm whether the observed ferromagnetic properties in some other Mn-doped group III-V semiconductors exist in AlMnN films, expected to show novel optical and magnetic characteristics. Samples are fabricated through magnetron sputtering deposition, with subsequent characterization using XRD, XPS, and VSM techniques. The results indicate an great improvement in the crystallinity of AlN when using an AlN/Pt multilayer as a seed layer, and successful doping of Mn into the AlN lattice in our work. AlMnN thin films show room-temperature ferromagnetism. The purpose of this work includes preparing Mn-doped AlN films with relatively high crystallinity, studying their magnetic, optical, and electrical properties, and then to understand the relationship between the electronic structure of the film and the physical properties, magnetic-electrical, magnetic-optical interactions inside such materials.

ABSTRACT. As technological advancements continue to shape agricultural industries, the integration of smart farming practices is becoming increasingly prevalent in the durian plantation sector. Research indicates that 10% of durian plants exhibit suboptimal growth, often leading to plant mortality. To address this issue, the automation of watering and fertilizing processes is proposed as a critical factor in enhancing durian plants' health and growth. In its implementation, the system uses a humidity sensor, pH sensor, ultrasonic sensor HC-SR04, a watering pump, and the ESP8266 module as a communication medium from each sensor node. The study demonstrates high sensor accuracy, with the soil moisture sensor achieving an average accuracy of 96.97%, the pH sensor at 98.9%, and the ultrasonic sensor for watering and fertilization at 96.97% and 97.7%, respectively. The deployment of this automated system is expected to significantly improve the overall growth and vitality of durian plants.

ABSTRACT. This paper proposes a method to estimate the relation between lectures offered at universities and the subject areas of certification exams. Education on information literacy is being promoted throughout Japan, and some universities support their students in taking certification exams related to information technology. If the relation between the contents of university lectures and the subject areas of certification exams is clear, students can make effective study plans by themselves. In this study, we obtained the relation by classifying the syllabi of the lectures in terms of the subject areas of the exams. In this paper, we examine the accuracy of the classification using actual university syllabi and the subject areas of a national exam. This allows us to automate some of the processes that should be done by persons with knowledge of lecture content and the subject areas of exams.

ABSTRACT. This paper proposes a method to identify the quality of Haiku works. Artificial intelligence technologies are expected to be applied to creative fields such as art. In this study, we propose a method to automatically discriminate the quality of Haiku, a literary art form. The proposed method estimates the quality of Haiku works by learning combinations of words used in works. In this paper, we conducted an experiment to estimate the grade of awards-winning works using results in actual large-scale contests. As a result, we revealed some of the factors that influence the quality of literary works.

ABSTRACT. This study focuses on visualizing and selecting attractive features in 3D captures of Buddhist statues using a deep learning approach. A Convolutional Neural Network (CNN) is constructed based on a questionnaire survey about the attractiveness of Buddhist statue images. Utilizing a Gradient-weighted Class Activation Mapping (Grad-CAM), the CNN visualizes important image regions that contribute to perceived attractiveness. The visualized features are then used to select images that enhance attractiveness, with validation provided by a comprehensive survey involving human participants. This combined approach of computational analysis and human feedback demonstrates Grad-CAM's capability in identifying appealing features in complex 3D datasets of buddhist images. The usefulness of these techniques is evaluated through experimental studies.

ABSTRACT. This study thoroughly explores pricing and order queue decisions for competing manufacturers in a circular supply chain. With a growing focus on environmental sustainability in business, two duopolistically competing manufacturers offer different products to their customers, involving both new and remanufactured products. This research investigates the impact of various products on market demand by considering selling prices and inventories. It highlights how the selling price in the demand function is influenced not only by its price but also by competitors' prices. Additionally, it emphasizes the pivotal role of the order queue in determining product inventory, represented by the order interval. By developing a Nash equilibrium model on the game theory, we determine the optimal decisions for pricing and ordering intervals to maximize profit for each manufacturer. The comprehensive numerical and sensitivity analysis demonstrates that increasing the selling price and order interval will reduce the manufacturer's profit. On the other hand, increasing the competitors' selling price and order interval will strategically increase the manufacturer's profit. Furthermore, increasing the wholesale price and holding cost will decrease the order interval, increase the selling price, and ultimately reduce profit. The managerial insights summarize that it is imperative for a manufacturer to determine the optimal selling price and order interval to gain a competitive advantage when making pricing and order queue decisions.

ABSTRACT. In many manufacturing companies, where manual tasks such as assembly are still performed by hand, it is as important as ever to improve worker performance. We have conducted a number of experimental studies to investigate the impact of worker aptitude. In our previous studies, we collected data from 249 workers and conducted a correlation analysis between their five super traits of the FFPQ-50, which is an abbreviation of the Five Factor Personality Questionnaire, and their assembly performance. It was confirmed that among the five super traits, only workers’ unemotionality has a significant positive effect on their assembly performance. To improve our previous studies, we will use the cluster analysis method to examine how workers with different assembly performance differ in their five-factor personality. We aim to make several new contributions through the following investigations: (1) This study designs and conducts an experiment on assembly operations, using assembly time to quantitatively measure a worker's performance. This is different from most previous research, which has used questionnaire surveys or case study methods to subjectively assess work performance. (2) As most studies have paid attention to the relationship between workers' five-factor personality and job performance, this study is the first attempt to consider how workers' five super traits: extraversion, affiliation, control, emotionality, and playfulness, significantly affect their performance in assembly operations. (3) We conduct a factor analysis to measure the five super traits of the workers. Then, we cluster the workers based on their scores on the five super traits and their assembly time, and further examine the differences among these clusters. Based on the result, we intend to provide some key points for practitioners to conduct assembly operations more effectively.

ABSTRACT. The problem of staff scheduling in call centers is crucial because efficient staffing can enhance work efficiency, reduce costs, and ensure adequate customer service. Previously, we used the set covering model to address the day shift scheduling challenge in multi-task call centers. To avoid enumerating all possible time slots and task combinations, we introduced a heuristic algorithm that reduces the number of combinations and effectively finds the optimal solution. Subsequently, we considered the on-site conditions and identified shortcomings in the original model. The original model sometimes resulted in surplus staff skills while still having unmet task demands. Additionally, extensive numerical experiments revealed instances where some tasks were not assigned at all. Therefore, in this study, we introduce new constraints and improve the model. First, we shorten the time slots from one hour to half an hour, allowing for a more precise allocation of task demands. Second, we add new decision variables and constraints to ensure that no tasks are left unassigned. Finally, we include constraints to prevent significant discrepancies in staffing levels during breaks.

ABSTRACT. Company TRU, a major toy retailer, has often experienced inventory replenishment and demand forecast inaccuracy problems. This study investigates the key factors causing these issues including how having a high number of product offerings creates challenges that affect the company’s inventory management. It also examines techniques to address these problems. Additionally, this study aims to identify a demand forecasting method that can provide high accuracy for product ranges with high demand volatility to improve future demand forecasts. Both qualitative and quantitative data were collected for analysis. Root cause analysis tools, namely the Cause-and-Effect Diagram and Nominal Group Technique, were used to gain insights into the causes of inventory inaccuracy. ABC/XYZ analysis was applied to the collected data to uncover potential gaps in product classification so as to improve the replenishment process. A seasonality with trend forecasting method was applied to selected sample data to assess prediction accuracy for future demand needs. The findings revealed that about 28% of the total SKUs at Company TRU contribute to 90% of annual sales. Each product in inventory exhibits different levels of demand volatility and risk. Therefore, optimizing inventory replenishment accuracy can be achieved by understanding the importance of each SKU in relation to its contribution and demand characteristics. Interestingly, the findings suggest that demand forecasting methods that consider seasonality and trend factors tend to produce lower deviations from actual demand. In conclusion, this paper investigates the main causes of inventory inaccuracy with a focus on stock replenishment and future demand forecasting.

ABSTRACT. Thermal Barrier Coating system (TBC) consists of three layers: top coat layer (TC), bond coat layer (BC), and substrate material. The TC is mainly processed by atmospheric plasma spraying, but the columnar structure fabricated by physical vapor deposition showed better resistance to thermal exposure. The suspension plasma spraying (SPS) is a new coating technology to form columnar structural TC, but the performance SPS TC is needed to be evaluated. In this study, both the suspension plasma spraying (SPS) and atmospheric plasma spraying (APS) were used to fabricate TC. The BC was made by low pressure plasma spraying on a nickel-based superalloy (IN718). The thermal exposure tests were conducted at a temperature of 1000oC for up to 1000h in air. Moreover, the effects of the solution and aging treatment on the microstructure of the bond coat layer and the substrate and the interfacial fracture toughness of the TC/BC, which were evaluated by Vickers indentation and bending tests. It was found that the solution treatment can prohibit the mixed oxides formation, but the interfacial fracture toughness seems not sensitive to the thermally grown oxide (TGO). There is no big difference in the TGO layer and the interfacial fracture toughness between the SPS TC and APS TC after thermal exposure at 1000oC for 100h.

ABSTRACT. The cytoskeleton (actin and microtubule) is a key player in cell morphogenesis, motility, polarity determination, and control of the spatial arrangement of intracellular materials. As a designer of cell-sized systems, the cytoskeleton is also an attractive biomaterial. The control of the behavior of the cytoskeleton using its related proteins and synthetic molecules has good feasibility for the development of micro- and nano-scale devices. In this talk, I will introduce in vitro tools and systems to control the self-organization and spatiotemporal arrangement of the cytoskeletons. One of the key technologies is protein micropatterning and microfabrication, which can organize the cytoskeleton into arbitrary geometric microscale structures. These geometric structures enable the control of the polarized movement of the cytoskeleton. Furthermore, optogenetic technology allows for on/off control of cytoskeletal motility. Artificial tools synthesized through integration with DNA nanotechnology can precisely control the spatial arrangement of the cytoskeleton with accuracy on the order of tens of nanometers, enabling the realization of hierarchical structures similar to the molecular structure of muscles. These methods are well-suited for controlling the molecular dynamics of the cytoskeleton. By integrating these technologies, it is expected that they will be useful in designing and controlling the operation of more macroscopic molecular systems (such as molecular robots) composed of cytoskeletal components.

ABSTRACT. Dielectric elastomers (DE) can convert mechanical energy into electrical energy due to its variability in capacity. A vibration energy harvesting device based on DE can be used as an independent power source for battery-free wireless sensors. Previous research has shown that its power generation output can be enhanced by increasing the permittivity of DE. In this study, to make a DE with high permittivity, we filled the DE with rod-like high permittivity (TiO2) particles. Then we measured the permittivity and evaluated the generation output characteristics of it. The conclusion is that the permittivity of DE be increased by filling DE with rod-like TiO2, but it decreases significantly when the DE is stretched. So, contrary to expectations, the generation output coefficient of DE cannot be increased. Therefore, to improve the power generation output performance of DE device, it is essential not only to increase the permittivity of DE but also to minimize the change in it due to stretching.

ABSTRACT. Nanomaterials show promise as potential candidates for microelectromechanical systems (MEMS). In this presentation, we will discuss a new ultrafine-scale Ni/NiW layered composite that can be used for mechanical components in MEMS devices. We designed the Ni/Ni-W layered composites with different thickness ratios of the Ni layer to the Ni-W layer and fabricated them using the double-bath electrodeposition method. We then conducted a systematic investigation of the tensile properties and plastic deformation behavior of the ultrafine-scale layered composites. Our results show that the strength/ductility synergy of Ni/Ni-W layered composites with a large thickness ratio is improved compared to that of monolithic Ni, due to the enhanced co-deformation ability of the nanograined Ni-W layers as the Ni-W layer thickness decreases. Additionally, we observed a transition in the fracture behavior from the coexistence of channel cracks and micro shear bands to predominantly micro shear bands as the Ni-W layer thickness decreases. Using finite element simulations and theoretical calculations, we proposed a plastic deformation map controlled by the length scale and flow stress for the Ni-W layers. These findings offer a potential strategy for the design and development of high-performance materials for mechanical components in MEMS devices.

ABSTRACT. In this talk, I will be introducing water-based synthesis of metal-organic frameworks (MOFs) that was first discovered by my group in 2013. After that, my group has devoted to extend this concept to utilize MOFs for (1) enzyme immobilization, (2) water/ethanol pervaporation, (3) highly efficient heterogeneous catalysis for biomass and waste plastic conversion, (4) highly selective ionic membranes for osmotic power generation, and (5) microfluidic mass production. All these applications are for the carbon neutral society. In addition, because I am having a joint position in National Health Research Institutes, I will also introduce some bio-medical applications (such as Keloid treatment) using water-based synthesized MOFs.

ABSTRACT. Ionic electroactive polymer actuators have attracted wide attention due to their capability of producing desired deformation under low voltages by ion diffusion. However, the actuators are always subjected to a slow response and fatal delamination at the bonding interface during deformation. Here, we report a novel polyimide/gold/bismuth (PI/Au/Bi) actuator driven by the electrochemical redox of PI with tunable active/passive layer thickness to generate large and tunable strains, where metallic Bi is indispensable to promote the actuating behavior by enhancing the reversible redox of PI. Much faster charge transportation and better conductivity of the PI/Au/Bi film were observed after coating with Bi. The actuator demonstrated large and tunable strains under a long service life owing to the fact that PI acted as both the active and passive layers, which effectively ruled out the delamination issue. This work not only develops a bismuth-enhanced ionic actuator but finds a new use for low-dielectric constant polymers rather than conductive polymers as actuator materials.

ABSTRACT. Applying photocatalytic technology to remove pollutants from wastewater offers an effective solution to environmental contamination. However, creating efficient, recyclable, multifunctional photocatalysts remains a significant challenge. In this study, MoS₂/BN composites were successfully synthesized via a hydrothermal method and characterized using various technological techniques. These composites demonstrated enhanced and persistent photocatalytic activity for removing multiple pollutants. Specifically, the 10% MoS₂/BN composite exhibited optimal performance, achieving a 96% removal efficiency for Cr (VI) under visible light. Detailed studies were conducted on the influence of factors such as Cr (VI) concentration, catalyst dosage, solution pH, water quality, and inorganic anions on Cr (VI) reduction. Additionally, the nanocomposite displayed remarkable photocatalytic properties, achieving approximately 98% degradation of methylene blue dye within 60 minutes under visible light irradiation. This high efficiency is attributed to its effective absorption of visible light, enhancing the generation of reactive species necessary for dye degradation. The intimate interface between the inorganic and organic phases significantly improved the transport efficiency of photogenerated carriers, reduced the recombination probability of electrons and holes, and enhanced the photocatalytic efficiency for Cr (VI) reduction. The optimized MoS₂/BN nanocomposite catalyst demonstrated notable photocatalytic activity and stability in reducing Cr (VI) in a neutral solution. This work offers a new perspective on designing efficient and promising inorganic/organic heterojunction photocatalysts for addressing Cr (VI) contamination in neutral solutions.

ABSTRACT. Many high entropy alloys show high strength, high toughness, and excellent corrosion resistance. On the other hand, such mechanical properties and chemical stability are influenced mainly by the composition distribution and the microstructure. Here in this work, a series of CrMnFeCoNi alloys were fabricated by ball milling and spark plasm sintering. Their crystal structure, density, hardness, and corrosion resistance were investigated. As a result, the ball milling achieved the alloying of Cr, Mn, Fe, Co, and Ni with a higher alloying degree after a longer time of milling to form a mixed powder. However, some Cr-rich particles cannot be thoroughly dispersed even through a more extended time milling of 12.0 h. The Cr-rich particle remained in the sintered alloy, forming a Cr-rich zone, which cannot be completely dissolved, even prolonging the sintering time to 12.0 h. Mn, C, and O were also included in the Cr-rich zone. Fcc-type crystals were detected from the sintered alloy with a small amount of chromium carbide. Some chromium carbide decomposed after 6.0 h sintering. The hardness of the sintered alloy generally increased with the increase of sintering time. However, short milling / long sintering or long milling / short sintering achieved high hardness in this study. The Cr-rich zone enforces the alloy to achieve high hardness. The highest corrosion resistance was obtained on the 12.0 h milled and 6.0 h sintered specimens in the 3.5% NaCl aqueous solution. Dissolution occurred from grain phase boundaries around the Cr-rich zone.

ABSTRACT. In 1792, a major collapse occurred at the Unzen Volcano on the Shimabara Peninsula, Kyushu Island, Japan. A large amount of earth and sand washed down into the Ariake Sea, engulfing the castle town and generating a huge tsunami with an inundation height of more than 10 meters. This catastrophe killed approximately 15,000 people in the sea-facing prefectures of Kumamoto and Nagasaki and was the largest volcanic disaster in the history of Japan. In recent years, numerical analysis of historical tsunami events has been widely used. However, there are many difficulties in simulating non-seismic tsunamis. Landslide-type tsunamis, a typical example, occur infrequently yet tend to cause severe damage. In this study, I attempt to simulate the 1792 Unzen tsunami using OpenFOAM, an open-source computational fluid dynamics (CFD) software, to construct a numerical model consistent with the distribution of tsunami deposits and historical records. It is of the utmost importance to clarify the actual conditions of the 1792 Unzen tsunami in order to gain a deeper understanding of the phenomenon and to be able to mitigate the impacts of future such events.

ABSTRACT. Tourism-dependent, small islands with indigenous communities face considerable obstacles in waste management. This research scrutinizes the waste management predicament on Lanyu (Orchid Island), Taiwan, domicile of the Tao tribe. The predicament is intensified by the tourism sector's waste, which burdens the island’s finite resources and fragile ecosystem. This study borrows successful waste management tactics from Salt Spring Island and Manitoulin Island in Canada and suggests inventive solutions that are custom-made for Lanyu’s distinct cultural and environmental circumstances. These solutions underscore the importance of community involvement, waste minimization at the origin, resource recuperation, and the amalgamation of traditional ecological wisdom with contemporary waste management technologies. By adopting a comprehensive approach in line with Taiwan’s pledge to zero waste and a circular economy, this research aspires to devise a sustainable waste management model for Lanyu, ensuring the preservation of its unique cultural heritage and primeval environment for future generations.

ABSTRACT. This study contributes to our understanding of how the tourism industry affects environmental sustainability of the small indigenous island of Orchid (Lanyu) through GHG emissions. It aligns with the Paris Agreement's mandate to reducing GHG emissions to maintain temperatures below 1.5°C and the 2050 Net Zero policy of Taiwan Taiwanese government. This study investigated the consumption related carbon dioxide emissions from energy (electricity generation and consumption), Municipal solid waste, and transport (scooters and motor vehicles). Specifically, the study estimates the carbon footprint of 45 km2 of Lanyu (Orchid) Island from 2011 through 2021 for both tourists and residents to demonstrate the exacerbation effect of the tourism, since the island is one of the tourist’s hotspots for Taiwan, patronized by close to 200,000 tourists annually. Furthermore, we explored the carbon reduction potential of introducing electric scooters on the island in different constructed scenarios. We used IPCC default methodology using a database and emission coefficients for Taiwan. Preliminary results demonstrated that Lanyu had an annual carbon footprint of 17,279 tons-CO2 eq yr., and a total CF of 202,738 tons CO2 eq. with energy dominating the GHG emission basket. Not astonishingly, petroleum-based scooters contributed massively to the GHG emissions since they are the primary source of transport on the island, specifically for tourists. Ultimately, we suggest transitioning from petroleum-fueled scooters to electric scooters in order to decrease emissions in the transportation industry. Additionally, we propose exploring and expanding the use of renewable energy sources like solar and wind power on the island to reduce the emissions from the current diesel-generator energy system.

ABSTRACT. We focus on the magnetostatic analysis of SRM with a three-dimensional gap structure (3D-SRM) using the 3D finite element method (3D-FEM).3D-SRM models are classified into full model, 4-segment model, and 6-segment model. The inductance and static torque in each model are calculated. From the results obtained, errors are calculated, and their factors are clarified.

ABSTRACT. This paper discusses the dynamic wireless power transfer (DWPT) charging technology for electric vehicles, which allows for continuous charging of the vehicles while they are in motion. This technology has the potential to decrease the required battery capacity of the vehicles and increase their driving range. The research paper is demonstrated by simulating the operation of a wireless power system using a 5 kW 85 kHz high-frequency inverter with DC input voltage at 400 V via transmission coils. The power transmission is designed to support dynamic wireless transmission and the system uses an LCC-S compensator in order to control the output voltage with the desired level, a dc-to-dc converter is used to control the charging current at the maximum rate of 16A. The performance of the system will be evaluated with a MATLAB/Simulink program.

ABSTRACT. An A-Frame storage rack is ideal for storing stone, granite and marble slabs. This study aims to introduce the concept of modal analysis to the verification of finite element model (FEM) of stone storage racks to confirm the results of finite element analysis (FEA) and further modify structural design to improve the seismic performance of the storage racks in earthquakes. By examining the existing A-Frame stone slab racks, a complete FEM was established, and the modal parameters obtained from experimental modal analysis (EMA), simple harmonic analysis and modal analysis in ANSYS were used to verify the reliability of the model. The structural strength of the storage racks is analyzed and the consistency of the damage location is checked to provide a reference for structural modifications. By using the practical measured earthquake signal as excitation, we conduct structural seismic strength analysis to simulate the stress and deformation of the storage frame during the earthquake. In addition, on-site measurements were used to obtain the dimensions of key components of the storage rack structure and locking holes, and the geometric and contact conditions were appropriately corrected to improve the reliability of the FEM and analysis results.

ABSTRACT. Organic sludge is challenging to treat due to its high water content and large volume, but it is rich in organic matter and nutrients, making it a potential biomass energy source. Conventional treatment can take weeks or even months for hydrolysis, prolonging the process and reducing efficiency. Efficient hydrolysis technology is key to solving this problem. By combining hydrothermal liquefaction with anaerobic methane fermentation, biomass methane can be recovered, reducing hydrolysis time and increasing conversion efficiency. This method enhances sludge recycling, improves feasibility, and significantly reduces treatment volumes and costs, aiding the industry in achieving net-zero carbon reduction goals. However, specific operating parameters and technical feasibility are critical considerations. This study aimed to optimize hydrothermal liquefaction technology using an experimental design method to enhance methane fermentation efficiency for organic sludge, aiding in sludge reduction and bioenergy production. First, the optimal operating parameters (temperature and pressure) for improving gas production efficiency during anaerobic fermentation under hydrothermal conditions were analyzed. Next, the BMP test evaluated methane potential during the hydrothermal anaerobic fermentation process and analyzed water quality changes before and after the reaction. Finally, the relationship between hydrothermal parameters and biogases (hydrogen and methane) produced during anaerobic fermentation was investigated to determine the optimal operating conditions. These studies will improve resource utilization efficiency and biomass production from organic sludge. The preliminary results indicated that hydrothermal liquefaction at 100 °C and 180 °C affected various indicators differently under different pressures. Among these, 100 °C and 60 kg/cm² yielded the best results, showing a balanced performance across all indicators. This condition achieved optimal removal of nitrogen, total solids, suspended solids, total dissolved solids, and COD, with a moderate pH value. It was identified as the best operating condition for anaerobic fermentation to produce hydrogen and methane gas under hydrothermal liquefaction conditions.

ABSTRACT. This study introduces a new biosorbent derived from Delonix regia bark-activated carbon to efficiently remove Chromium Cr(VI) metal ions from aqueous systems. The biosorbent was synthesized from the bark powder of the plant species and chemically activated with phosphoric acid. The biosorbent was characterized using FTIR, SEM, and BET to determine its functional properties and structural morphology. The batch adsorption experiments examined the optimal conditions for Cr(VI) metal ion adsorption, identifying that the highest removal efficiency occurred at pH levels of 2. The ideal adsorbent dosage was determined to be 2.5 g/L, with equilibrium achieved at a contact time of 60 minutes at the optimal temperature of about 303 K for a Cr(VI) metal ion concentration of 20 mg/L. Various isotherm models were applied to the adsorption equilibrium values, revealing that the adsorbent had a maximum removal capacity of approximately 224.8 mg/g for Cr(VI) metal ions. The adsorption process of Cr(VI) on the DAC biosorbent was best described by the Freundlich isotherm, indicating multilayer adsorption. The kinetic data fit well with the pseudo-second-order model. Thermodynamic parameters suggested that the adsorption process was spontaneous, exothermic, and feasible across different temperatures. Furthermore, the desorption studies showed that the DAC biosorbent can easily be rejuvenated and utilized several cycles with high adsorption capacity. These findings indicate that the developed adsorbent is environmentally friendly and effective for removing Cr(VI) from water systems.

ABSTRACT. Functional magnetic soft materials-based robots and devices have garnered significant attention from both academia and industry over recent decades due to their versatile programmable adaptation, deformation, and locomotion capabilities in response to external stimuli. Through design in materials composition, mechanical structures, and the external actuation field, various devices have been developed and shown promising applications in diverse scenarios, including but not limited to healthcare, haptics, and electronics. However, the manufacturing of these cutting-edge material systems, which involves multiple steps in microstructure and materials processing, is still highly dependent on manual operations. Consequently, these promising devices currently have low yield, inconsistent performance, and stay at the lab prototype stages, making it challenging for real-world translations. To this end, we propose automation for the manufacturing of functional magnetic soft materials. The use-inspired path planning, control algorithms, and process optimization will be designed and tested on the industrial-level robotic arms (e.g., YASKAWA) to achieve the fast, consistent, and mass production of representative miniature devices based on magnetic soft materials. Such efforts will help create new standards for this emerging field and lead the global market of academia and industry. More importantly, the active collaboration between FIT and UH Manoa will enhance academic exchange and engage students in robotics, materials, fabrications, and MEMs-related fields. This partnership is poised to benefit the long-term sustainable development of both research institutions.

ABSTRACT. Leather is a fiber-reinforced material with a more concentrated fiber distribution in three dimensions perpendicular to the tangential plane than in-plane. The asymmetric dispersion of fibers can have a significant effect on the mechanical properties of natural leather. The transverse isotropic constitutive model is unable to accurately describe the anisotropy of natural leather. Accordingly, we have devised a novel anisotropic theoretical framework that incorporates asymmetric fiber dispersion, with the objective of accurately characterizing the mechanical behavior of anisotropy with asymmetric fiber distribution. Our approach entails the incorporation of the Yeoh model into the theoretical framework, as well as the introduction of a specific anisotropy term within the strain energy function, with the objective of describing the nonlinear properties. By fitting the theoretical results of the model to tensile test data of natural leather specimens, the structural and material parameters were determined. We provided specific stress tensors to enable finite element analysis. Our finite element analysis investigates the effect of asymmetric fiber dispersion on the mechanical response under uniaxial and biaxial stretching. By simulating the tensile behavior of natural leather specimens under different tensile angles, we observe a non-homogeneous stress distribution and non-homogeneous deformation due to fiber families under fixed stretching. This theoretical framework based on a continuum model provides a theoretical reference for describing the mechanical properties of leather materials with asymmetric fiber dispersion.

ABSTRACT. AS global concern for environmental issues grows, nations are increasingly adopting carbon emission policies. This study investigates the implications of the EU’s carbon trading system on Taiwan’s steel industry, focusing on carbon emissions within the framework of EU hot-rolled steel’s environmental footprint. The research examines the operational dynamics and efficacy of the EU Emissions Trading System (ETS) in mitigating greenhouse gas emissions, while also assessing its impact on the European steel sector. Employing Simpro7.0 software, the study evaluates the environmental footprint of hot-rolled steel production and uses time series analysis to examine carbon emission trends over time. Findings indicate that the EU ETS significantly reduces emission, fostering the adoption of green technologies and low-carbon transformations within enterprises. Additionally, the study analyzes the efficacy of the Carbon Border Adjustment Mechanism (CBAM) in preventing carbon leakage. Consequently, Taiwan’s steel industry is anticipated to encounter pressures for green transformation and international competitiveness post the implementation of carbon pricing policies. Drawing lessons from the EU’s experience, Taiwan is encouraged to proactively implement emission reduction measures such as enhancing energy efficiency, adopting low-carbon technologies, and optimizing production process. This study aims to support for future policy formulation. Preliminary result suggest a potential reduction in carbon emission and an increase in sustainable practices within Taiwan’s steel sector.

ABSTRACT. Of the eight planets in our solar system, it was known that liquid water once existed on Mars. Other evidence indicates that it has had a warm and humid climate for a long time, and that it has compounds of iron and sulfur in a redox state that provide a source of energy for microorganisms. Therefore, Mars is considered to be a planet very similar to Earth, with the potential for the existence of life. Biological cells carry out various life-sustaining reactions within the cell, and proteins catalyze these reactions. In other words, the possession of proteins is considered an important characteristic of living organisms. Protein amino acids have been found to be present in many carbonaceous meteorites and in surface samples collected from the asteroid Ryugu, which orbits between Earth and Mars. Thus, it is considered highly likely that if life exists on any celestial body other than Earth, it would utilize proteins. Proteins are complex molecules comparing numerous amino acids, the hydrolysis of which yields 20 distinct types, which are relatively simple to identify. By analyzing the amino acids obtained by hydrolyzing proteins, it is possible to investigate the existence of life based on the results. Since hydrochloric acid of high concentration is typically employed for protein hydrolysis, there is a risk that the hydrochloric acid may volatilize and corrode the probe if utilized in a spacecraft designed to search for life on Mars. Consequently, this study aims to identyfy optimal conditions for efficient hydrolysis through the use of a solid acid catalyst in lieu of hydrochloric acid. In this experiment, hydrolysis was conducted using cation exchange resin Amberlyst and synthetic zeolite as solid acid catalysts. The experimental results demonstrated that the hydrolysis process utilizing Amberlyst resulted in a higher amino acid recovery than that empolying zeolite.

ABSTRACT. Silicon nitride (Si₃N₄) fine powder has been used as a mold release coating for producing the solar grade Si polycrystals. Therefore, it was well known that molten Si basically did not wet the Si₃N₄ surface. Many studies have been conducted on the wettability of molten Si and Si alloys to Si₃N₄, which reported that the type of metal added to Si and the atmosphere had a significant effect on the wettability, and that oxygen partial pressure plays a major role for the wettability between Si₃N₄ and molten Si and Si-alloys. It was reported that silicon oxynitride present on the surface of Si₃N₄ particles deteriorated the wettability of molten Si. There have been few reports on the effect of active metals added for improving wettability. The purpose of this study is to investigate the wettability of Si3N4Si₃N₄ by three active metal silicides MSix (M = Ti, Zr, Y). The effects of the type and amount of active metal added to Si and the heat treatment conditions (temperature and atmosphere) on wettability were investigated. It was found that these active metal silicides showed good wettability in the vacuum atmosphere, while they did not wet at all in the Ar atmosphere. It was also confirmed that the wetting angle in a vacuum atmosphere was basically determined by the equilibrium oxygen partial pressure of M/MOx (M=active metals). The interfaces of active metal silicides and Si₃N₄ substrates were analyzed by FE-SEM/EDS.

ABSTRACT. As the spread of various devices and contents using the Internet increases, the characteristics of traffic on the Internet have been diverse. Therefore, network traffic classification is important for providing Quality of Service (QoS), detecting malicious behavior, and so on. Our previous study revealed the differences in traffic characteristics between Internet of Things (IoT) devices, which are new devices connected to the Internet, and traditional rich content in the wireless LAN (WLAN). Furthermore, we showed the accuracy of traffic classification by machine learning using a part of traffic flow for four types of traffic classes: video, IoT, voice, and Web. However, with the recent introduction of the Internet, the traffic volume of various online games has been increasing, and gaming devices and users have become diverse. Gaming devices include high-specification PCs, cross-reality (XR) smart glasses, and small devices, e.g., smartphones. Hardware specifications will impact the game's visualization quality. In addition, game genres will also impact the traffic volume and characteristics. Hence, we expect that hardware specifications and game genres impact the traffic volume and characteristics of online games. This study will clarify the traffic characteristics of online games using different devices and game genres in packet-level traffic analysis, e.g., packet size, packet inter-arrival time, and protocols, and differences with traditional rich contents, voice, and IoT traffic in WLAN. In addition, we will discuss the need for a classification and estimation method for the game traffic on the Internet.

ABSTRACT. This research focuses on the development of a pure electric unmanned vessel designed for river water quality monitoring, exploring the feasibility of using such a vessel for future applications in this field. The goal is to achieve precise positioning, route planning, real-time image transmission, and water quality data monitoring in rivers using the pure electric unmanned vessel. The primary components of the system include a 2.4G high-power wireless data transmission system, an M9N GPS antenna, and various water quality sensors. The control system utilizes an unmanned vehicle control system for remote operation, while water quality monitoring is handled by a microcontroller unit (MCU) equipped with five types of sensors to measure turbidity, total dissolved solids (TDS), electrical conductivity (EC), oxidation-reduction potential (ORP), and pH levels, recording data at fixed points in the river. This research also aligns with the goal of net-zero carbon emissions and the United Nations Sustainable Development Goals (SDGs) for the sustainable use of ocean resources. The autonomous water quality monitoring pure electric unmanned vessel can operate in remote control mode and utilize the M9N GPS antenna and 2.4G high-power wireless data transmission system for route planning, image transmission, and water quality monitoring, thereby achieving the objective of unmanned autonomous detection.

ABSTRACT. A facile method for preparation of Pd/Ni nanoparticle(NPs)-embedded porous carbon has been developed and its catalytic performance in Suzuki-Miyaura cross coupling reaction was evaluated. Palladium(Ⅱ) acetate (Pd(OAc)2), as precursor of Pd NPs, were immobilized in the pores of Ni-MOF-74 using supercritical carbon dioxide(scCO₂). Pd/Ni NPs prepared from Pd(OAc)2-loaded Ni-MOF-74 by reduction and decomposition in a stream of H2 at 573 K. During the simultaneous reduction and decomposition of Pd(OAc)2 and Ni-MOF-74, Pd/Ni NPs get dispersed within the porous carbon (Pd/Ni@C). Scanning transmission electron microscopy (STEM) clearly demonstrated that the Pd/Ni NPs were successfully immobilized in the porous carbon. Pd/Ni@C exhibited high catalytic activity in Suzuki-Miyaura coupling reactions, while its Pd contents were lower than commercially available Pd@C. The synergistic interaction between Ni and Pd accelerate the catalytic performance.

ABSTRACT. Metal-nanoparticle (NP)/metal−organic framework (MOF) composites have attracted considerable attention as heterogeneous catalysts. Compared with porous carbon, silica, and alumina, the charge-transfer interaction between the metal NPs and the MOF accelerated the catalytic activity. In this study, PdRu bimetallic NPs were successfully immobilized on MOFs such as MIL-101(Cr) by using supercritical carbon dioxide. The STEM-EDX images show a uniform 3D distribution of the PdRu bimetallic NPs on MIL-101(Cr). The resulting PdRu@MIL-101(Cr) catalyst exhibited higher CO oxidation than monometal/MOF composites such as Pd@MIL-101(Cr) and Ru@MIL-101(Cr). Furthermore, PdRu@MIL-101(Cr) exhibited higher catalytic activity than PdRu@SiO2. This is because the particle size of the PdRu bimetallic NPs in MIL-101(Cr) was within the range of 2-3 nm. The synergistic effects were based on the combination of two metals, Pd and Ru, small bimetal particle formation, and charge-transfer interactions between the bimetal NPs and the MOF. These factors enhance the catalytic activity of the bimetal/MOF composites.

ABSTRACT. Metal–organic frameworks (MOFs) are efficient adsorbents for the removal of hazardous materials. An MOF based on 1,3,5-benzenetricarboxylic acid (BTC), Cu3(BTC)2, is prepared via phase separation using supercritical CO2 (scCO2) as a nonsolvent for the polymer solution. The prepared MOF is then loaded onto microporous polystyrene membranes. To evaluate the performance of Cu3(BTC)2-loaded microporous polystyrene membranes for pollutant removal from water, they are tested for the separation of methylene blue (MB) dye from an aqueous solution. Prior to the preparation of the Cu3(BTC)2-loaded microporous polystyrene membranes, Cu3(BTC)2 is activated with scCO2. After the activation with scCO2, the internal surface area of Cu3(BTC)2 and its MB adsorption increase. A toluene solution of polystyrene containing Cu3(BTC)2 particles is prepared, and scCO2 is introduced to induce the phase separation of the polymer solution. A Cu3(BTC)2-loaded microporous polystyrene membrane is obtained without the collapse of the structure after the release of the CO2 pressure. MB can be readily and rapidly removed from aqueous solutions using Cu3(BTC)2-loaded microporous polystyrene membranes. The removal efficiencies for aqueous MB solution were high, and removal efficiencies reached 92.8%.

ABSTRACT. Zeolitic imidazolate frameworks (ZIF-8), referred to as ZIF-8, were synthesized and used for immobilization of lipase PS(LPS). After the preparation of ZIF-8 within a particular solvent, the internal surface area of ZIF-8 increased as a result of the scCO2 drying method. Higher amount of LPS could be immobilized into the pores of ZIF-8 by utilizing a scCO2–assisted drying. Immobilization efficiency of ZIF-8 and enzymatic catalytic performance were performed for esterification of benzyl alcohol with lauric acid in organic media. LPS@ZIF-8 showed higher enzymatic activity compared with conventional drying. Furthermore, the LPS@ZIF-8 showed high storage stability.

ABSTRACT. The cost of catalysts has always been a bottleneck restricting the development of water electrolysis. Unfolding the alternative of precious metals is becoming a charismatic research objective more than ever before. The cobalt-based catalysts display advantages such as high catalytic activity, low cost, easy recovery and high selectivity in specific applications. Besides, the supports are an another efficacious factor to increase the catalyst performance. In our studies, the MgO@C as a carbon support is utilized to prepare the Co/MgO@C composite catalyst. Through the SEM measurements, it is found that the Co homogeneously disperses on the surface of MgO@C. After carrying out the electrochemical evaluations, the Co/MgO@C displays the fantastic hydrogen evolution reaction (HER) performance in alkaline conditions. As an example, it is found that the overpotential of Co/MgO@C is 163 mV at a current density of 10 mA cm-2, and the tafel slope is 173 mV dec-1. These relatively high HER performance indicate that the Co/MgO@C possesses the alternative feasibility for precious metals in the HER field.

ABSTRACT. Pt nanoparticles were successfully immobilized inside the pores of a metal organic framework (MOF) like MIL-53(Al) using supercritical carbon dioxide (scCO2), without Pt nanoparticles aggregating on the external surfaces of framework. After its preparation in a particular solvent, the internal surface area of MIL-53(Al) increased slightly due to the scCO2 drying method. The precursor H2PtCl6 could also be impregnated into the MOF pores using a scCO2-ethanol solution. These synthesized samples were reduced by treating in a stream of H2 at 473 K. During the reduction, the formed Pt nanoparticles get dispersed within the MIL-53(Al). The resulting Pt@MIL-53(Al) composites represent the highly active MOF-immobilized metal nanocrystals for catalytic hydrogen(H)-deuterium(D) exchange reaction.

ABSTRACT. Microporous polyethylene membranes were prepared by the phase separation process using the supercritical CO2 as a nonsolvent for the polymer solution. The thin polymer solution in a laboratory dish was located inside a cell and the supercritical CO2 was introduced to induce the phase separation. The dry flat microporous membranes were obtained without collapse of the structure after the CO2 pressure was diminished. Effects of the experimental conditions such as the CO2 temperature on the membrane porosity were investigated. Oil could be separated from an oil/water mixture by simple immersing the porous polyethylene membranes into the mixture.

ABSTRACT. This paper discusses the effect of the heat transfer coefficient on the accuracy of gear simulation during the carburizing and quenching process. Carburizing and quenching is an important industrial technique to improve the surface hardness and wear resistance of gears, enabling better mechanical properties and fatigue strength. Quenching oil is typically used as the coolant in carburizing and quenching. When the gear is heated above the austenitizing temperature and then placed into quenching oil, complex phenomena such as nucleate boiling and vapor film formation occur. Depending on the cooling rate in different parts of the material, the austenite phase transforms into either martensite or bainite. The differences in transformation structures and transformation plasticity cause transformation expansion and plastic distortion, which are major reasons for distortion after carburizing and quenching. Therefore, effective research on the heat treatment of gears is essential. This paper measures the cooling curves at the pitch circle and tooth root positions of the gear during quenching in quenching oil, providing a basis for calculating the heat transfer coefficient. Numerical simulations of the quenching process were performed using boundary conditions with one heat transfer coefficient and with two different heat transfer coefficients.

ABSTRACT. Curcumin, a natural polyphenolic compound derived from the turmeric plant, is widely recognized for its pharmacological activities, including anti-inflammatory, antioxidant, and anticancer properties. However, its clinical application is hindered by poor aqueous solubility and low bioavailability. To address these limitations, this study investigated the formation of an inclusion complex between curcumin and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) to enhance its solubility. The resulting Cur/HP-β-CD complex was incorporated into hydrogel beads composed of alginate and chitosan derivatives (carboxyethyl chitosan and hydroxyethyl acrylate chitosan) to develop a model drug delivery system. Characterization of the Cur/HP-β-CD complex was conducted using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and ultraviolet-visible spectroscopy (UV). The study evaluated solubility enhancement, in vitro drug release kinetics, antimicrobial activity against Staphylococcus aureus and Escherichia coli, cytotoxicity against HT-29 cancer cells and Vero normal cells, and nitric oxide scavenging activity. These findings provide a foundation for developing enhanced curcumin delivery systems with potential applications in improving therapeutic efficacy and bioavailability in various medical and pharmaceutical fields.

ABSTRACT. Film-forming systems (FFS), as non-solid dosage forms, are attractive for topical drug delivery due to their ability to form a film in situ on the skin upon application. To minimize drying time, alcohol-water solutions are commonly used as solvents in these systems. This study aimed to enhance the solubility of chitosan in alcoholic solutions through chemical modification for film-forming systems, while also enhancing its antibacterial and anti-inflammatory properties. Modified chitosan derivatives (CECS-CA) were synthesized by incorporating cinnamaldehyde and acrylic acid using Schiff base and Michael addition reactions. The chemical structures of the synthesized chitosan derivatives were characterized using 1H-NMR, 13C-NMR, and FT-IR techniques, confirming the presence of cinnamyl and carbonyl groups in the structure. Detailed analysis employing HSQC and DEPT techniques further elucidated the positions of carbons attached to the amine moiety in CECS-CA. Verification of reductive amination was achieved using UV-visible spectrophotometry, revealing a shift to lower wavelength absorption. Solubility tests demonstrated that CECS-CA exhibited significantly improved solubility in alcohol-water solvents compared to native chitosan, indicating potential for film formation through solvent evaporation. Evaluation of antibacterial and anti-inflammatory properties further demonstrated the enhanced functionalities of CECS-CA. These findings highlight the potential of modified chitosan derivatives like CECS-CA as versatile materials for various biomedical applications.

ABSTRACT. Carbon dots (CDs) represent a promising class of fluorophores due to their low toxicity, biocompatibility, excellent photostability, and ease of synthesis. This research aimed to develop a light-sensitive screen-printing ink using carbon quantum dot precursors (BCUZn, BCUAg, and BCU) derived from citric acid as the carbon source, urea as the nitrogen source, and borax as the boron source, doped with zinc (Zn) and silver (Ag). The carbon quantum dots were synthesized via a microwave-assisted technique. Characterization techniques such as transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) confirmed the morphology and chemical structure of the CDs, while UV-visible (UV-Vis) and fluorescence spectroscopy assessed their optical properties. Photoluminescent properties were evaluated using fluorescence spectrophotometry, revealing similar maximum excitation wavelengths for each type of carbon quantum dot: BCU = 347 nm, BCUZn = 345 nm, and BCUAg = 350 nm. Screen-printing inks formulated with BCUZn were applied to various surfaces such as cotton fabric and bond paper, exhibiting invisible patterns under visible light but fluorescing blue under UV light. This screen-printing ink holds promise for applications in anti-counterfeiting printing on diverse materials.

ABSTRACT. This study developed a three-layer wound dressing patch designed for controlled salicylate release. The inner layer consisted of cellulose fabric coated with 1% or 2% w/v chitosan, the middle layer featured a salicylate gelatin film, and the outer layer was composed of 3M-Medipore. Salicylate release from these patches was evaluated in a PBS solution at 37°C, with absorbance measured at 296 nm using a UV-Vis spectrophotometer. Initial salicylate release rates were rapid for all models. The uncoated and 1% chitosan-coated patches achieved complete release within 1 hour. Conversely, the 2% chitosan-coated patch showed slower release kinetics, reaching approximately 70% release within 2 hours and plateauing at around 80%.

ABSTRACT. Monodisperse titania nanosheets (mNS) are uniformly sized anionic plate-like inorganic particles with extremely large specific surface area. We have recently discovered a unique phenomenon that mNS are stacked one-dimensionally to form columnar nanofibers (ColNFs) [1]. In this study, ColNFs were functionalized with the photosensitizing dye tris(2,2'-bipyridyl) ruthenium(II) ([Ru(bpy)₃]²⁺) by exchanging the mNS counter cation, tetramethylammonium hydroxide (TMA⁺), with [Ru(bpy)₃]²⁺. As a result, the visible light responsive photocatalytic activity was imparted to ColNFs and the ColNF was stabilized by stronger electrostatic interactions between [Ru(bpy)₃]²⁺ and the mNS. The mNS solution was prepared by refluxing a mixed aqueous solution of TMA⁺ and titanium tetraisopropoxide, followed by addition of a [Ru(bpy)₃]²⁺ aqueous solution. The obtained solution is named as Ru(x)-mNS, where x is the equivalent ratio of [Ru(bpy)₃]²⁺ to the ion exchange capacity of NS) was prepared. We set x from 0 to 2.0. Thin film samples were obtained by drying Ru(0.80)-mNS on glass substrates for photocatalytic characterization. In the transmission electron microscopy (TEM) observation of the Ru(0.50)-mNS, nanofibers with the thickness of about 20 nm and the length of 100 nm were observed. Ru(0.80)-mNS showed longer string-like structures. In these TEM observations, stacking of the NSs with the intervals of 1.6-1.7 nm were observed inside the fiber. Considering the NS thickness of 0.65 nm and the diameter of [Ru(bpy)₃]²⁺ (1.13 nm), we confirmed that [Ru(bpy)₃]²⁺ replaced TMA+ and was introduced between layers inside the ColNF. Lastly, photocatalytic decomposition of formaldehyde was investigated by using the Ru(0.80)mNS as the photocatalyst. Significant CO2 generation compared to blank test was observed under visible light irradiation.

References [1] Miyamoto et al., Sci. Adv. 10, eadk6452 (2024)

ABSTRACT. Silicon carbide (SiC) ceramics have excellent properties such as high thermal conductivity, heat resistance, wear resistance, high hardness and low thermal expansion. However, their low strengths due to the low fracture toughness make it difficult to produce SiC ceramics with large sizes and complicated shapes. On the other hand, silicon nitride (Si₃N₄) ceramics have been known as ceramics materials with high strength and high toughness owing to the crack bridging mechanism by the β-Si₃N₄ rod-like crystals. In order to improve the mechanical properties of SiC ceramics, there have been numerous studies regarding SiC/Si₃N₄ composites. These studies have been limited to Si₃N₄ ceramics reinforced by SiC fine particles or whiskers (SiC<Si₃N₄), and few studies have reported SiC ceramics reinforced by Si₃N₄ particles or whiskers (SiC>Si₃N₄). The purpose of this study is to fabricate SiC/Si₃N₄ composite materials (SiC>Si₃N₄) reinforced by the β-Si₃N₄ rod-like crystals (whiskers) in order to improve the mechanical properties of SiC ceramics. In this work, a novel method for fabricating SiC/Si₃N₄ composites reinforced by the β-Si₃N₄ rod-like crystals has been proposed as follows; preparing porous Si₃N₄ bodies with porosity more than 50%; infiltrating phenolic resin into the porous bodies; heat-treatment of the porous Si₃N₄ bodies to convert phenolic resin to carbon; infiltrating molten Si into the porous Si₃N₄-carbon composite (reaction bonding). It was found that the infiltration of molten Si to the porous Si₃N₄ was incomplete, probably due to the insufficient infiltration of phenolic resin into the Si₃N₄ porous bodies. Therefore, an alternative method for fabricating SiC/Si₃N₄ composites, hot-pressing the powder mixture of SiC and the β-Si₃N₄ whisker with sintering additives, was developed. The microstructures and mechanical properties of sintered bodies were investigated.

ABSTRACT. Activated carbon plays an important role in improving the performance of Electric Double Layer Capacitors (EDLCs), and research has been conducted on controlling the pore structure of activated carbon, which has a very high specific surface area. However, breakthroughs in electrodes have been difficult to achieve by pore control alone. Therefore, research focusing on functional groups on the surface of activated carbon has been attracting attention in recent years. Performance improvement by acidic functional groups has been reported, but there have been few reports on basicity. 　Additionally, since the raw materials for small batteries such as button batteries undergo chemical reactions during charging and discharging utilizing lithium and other materials, performance degradation due to repeated use is a problem. Therefore, the miniaturization of electric double-layer capacitors, which can be charged and discharged only by adsorption and desorption of ions in the electrolyte, has attracted attention as a semi-permanent rechargeable battery. 　In this study, specific capacitance, internal resistance, energy density, and power density of coin cell electrodes were calculated from electrochemical measurements using basic activated carbon, and their characteristics were evaluated. The effects on performance in basic activated carbon samples were also discussed. 　As the result, the introduction of basic activated carbon resulted in an increase in specific capacitance and a decrease in internal resistance. This may have been influenced by the increased hydrophilicity due to the basicity of the activated carbon surface; basic functional groups containing N are known for their high electronegativity, which may have improved hydrophilicity by attracting proton　H+from water molecules in the aqueous electrolyte. It is concluded that the improved hydrophilicity is related to the increased surface area that contributes to the adsorption of ions from the improved leakage of the electrolyte in the charge/discharge process, and thus the improved performance was observed.