Research

The amount of produced slurry ice, which is useful for maintaining the freshness of marine animals, often exceeded the amount actually used because there was not a calculation method that took storage time into account. At our laboratory, we have developed a device to optimize the quality (salt concentration and water/ice mixing ratio) and quantity (shelf life) of slurry ice simultaneously and quickly on the spot based on the overall heat transfer coefficient of the storage container, as described earlier. Since this method can be applied to the production of fresh water-derived salt-free liquid ice, it can also be used for other food than marine animals (vegetables, fruits, and livestock), and we are currently working to obtain the rights to this invention.

Research

At the wholesale markets in fish and shellfish production and consumption areas, freshness is an important criterion in the determination of transaction prices, and the K value has been proposed as an evaluation index. However, since the K-value is calculated by sampling any part of a postmortem marine animal and analyzing the components after various pretreatments, real-time evaluation (understanding) at the distribution site is not possible. Aiming to solve this problem using an appropriate simulation method, we have developed a device that can evaluate the freshness and the best timing to eat fish and shellfish based on various information such as the type and size of the fish and shellfish, the elapsed time since death, and the storage temperature, using the method described above. We are currently working on the acquisition of the rights to the invention and for improvement of its portability (for use with smartphones, etc.). This device “MIRASAL” can also be applied to livestock animals such as beef, chicken, and pork.

Research

In general, porous structures with repeating units, such as diamond lattices, suffer from mechanical issues, such as fracture development, low energy absorption, and mechanical anisotropy due to these repeating units. To address these issues, we develop a novel porous structure with high mechanical performance for additive manufacturing. The structure is designed biomimetically based on the insights of bone biomechanics. It has a framework made up of 3D isotropically interconnected beams. Here, the beam lengths and bifurcation counts are arbitrarily determined using probability distributions without any repeated units. Furthermore, the structure can be manufactured through the powder bed fusion of a laser beam using metal powders and material extrusion using plastic filaments. Additionally, compression tests revealed that the structure exhibited suppressed fracture progress after the initial fracture and increased energy absorption. Moreover, the fracture behavior of the structure was found to be independent of the compression direction because of its structural isotropy.

Research

The composition of bile acids synthesized by the liver fluctuates with aging and excessive energy intake, and that can be estimated under these conditions. Therefore, by feeding a very small amount of a specific bile acids to experimental animals, it is possible to create a state that mimics the bile acid environment in the corresponding situation. We have found that this results in fatty liver and related pathologies. We also found that a mild deficiency of zinc is a pre-symptomatic disorder model for ulcerative colitis. These findings indicate that minor metabolic changes that occur continuously due to dietary bias (excess or deficiency) are involved in the onset of infectious and non-infectious diseases, and that the experimental system itself, which mimics the situation by controlling dietary components, can serve as a model of pre-symptomatic disorders. Currently, we are constructing various pre-symptomatic disorder models and analyze their pathogenic mechanisms. We are also using these systems to evaluate the functionality of foods.

Research

Ecosystem restoration after large-scale disturbance is often an urgent task, but it has often been difficult to establish a target plant species in a disturbed environment. A facilitator is a plant species that prompts the establishment of other species once it has been established. If we can detect and establish a facilitator in the respective disturbed areas to prompt the invasion and establishment of the target species there, it will be possible to quickly restore ecosystems in a cost-effective manner with minimal human effort. Therefore, this is an ecofriendly technology for ecosystem restoration.
So far, we have found that the white beak-sedge (Rhynchospora) is functioning as a facilitator in the post-mined peatland of Sarobetsu Mire, and the Mineyanagi willow in Mt. Komagatake in Oshima, Hokkaido. Microtopography modification has also been found effective as a means of introducing facilitators.

Research

In this presentation, we propose an experiment record management system based on interviews with researchers in actual nanocrystal device development. The system proposes an integrated method for the management of records of parameters used in experiments that have been stored and recorded separately, as well as the resulting experimental records. In addition, by extracting information from the paper summarizing the final experiment, we propose a method for analyzing the purpose and characteristics of a series of experiments conducted by researchers in detail, and for using it as the basis for discussing similarities between various cases. With this method, we are proposing a method of extracting useful information from unknown papers by using machine learning methods on a corpus of information manually extracted by a few people.

Research

The radio propagation environment inside a vehicle is a special environment that differs from the conventional propagation model due to multiple reflections caused by the surrounding metal and the presence of fixtures and passengers inside. It is therefore necessary to evaluate the characteristics of radio wave propagation, including the effects of absorption and scattering of radio waves by the bodies of passengers, to estimate the quality of the wireless connection under actual operational conditions. However, it is difficult to evaluate the propagation characteristics by actual measurement or simple numerical analysis (e.g., ray tracing). This study addresses modeling of the propagation environment in vehicles, which has been difficult in the past, and realizes a simulation method in a very large analysis space by using a supercomputer.

Research

We have summarized the requirements and functions of pro-beam road lighting to design specific light distribution of Pro-beam lighting to increase the visibility of pedestrians crossing the road through optical simulation and visibility evaluation experiments. Using the prototype light fixture, we have evaluated drivers’ visibility of pedestrians who are standing still and measured the time until drivers detect pedestrians at intersections using video images. As a result, we have confirmed that the Pro-beam lighting system provides higher visibility of the entire road space, including the oncoming lane, and helps drivers quickly detect pedestrians crossing the road not only from the right but also from the left. We are now working on the design and development of a light fixture for practical use as a road light by developing the prototype light fixture.

Research

Hokkaido University Information Initiative Center has established the Hokkaido University Academic Cloud, one of the largest academic clouds in Japan, and provides cloud services to researchers nationwide, including those concerning virtual and physical machines and their cluster systems, high-speed high-capacity cloud storage services, and machine learning and big data processing systems for research and development. We are also promoting research on fundamental technologies to realize nationwide cloud system collaboration and system construction to support researchers. Specific examples include the development of infrastructure technologies for cloud collaboration (authentication collaboration, etc.) and the construction of a test system (Fig. 1), resource allocation optimization in an intercloud environment, and the realization of a large-scale design optimization framework on a nationwide scale by linking supercomputers and intercloud infrastructure (Fig. 2). We are also conducting joint research with universities, research institutes and companies across the country.

Research

We are studying new structured optical fibers to overcome the limitation of existing optical fibers, optical fiber application technologies to ensure safety and security, ultra-compact optical circuits to support opticalization, and optical simulators to support the design of optical fibers and optical circuits.

Research

Using isolated small intestinal crypts and enteroids, which are three-dimensional small intestinal epithelial culture systems, we will elucidate the innate immunity of Paneth cells, which are intestinal epithelial cells (that secreteα-defensins), symbiosis with intestinal bacteria, regeneration and differentiation and other molecular mechanisms associated with various functions, taking advantage of state-of-the-art analytical methods such as confocal laser microscopy and flow cytometry. The intestine forms a network between various organs in the body and by analyzing the mechanism of the intestinal environment focused on the function of Paneth cells will make it possible to control the intestinal environment and create preventive measures and treatments for various diseases. From the perspective of the intestines, “food” and “drugs” virtually mean the same thing. We hope to contribute to the realization of a healthy longevity society through industry-academia-community collaboration based on the knowledge we have created.

Research

We have succeeded in establishing associations and similarities between different media, and developed an associative search scheme that takes ambiguity of multimedia information into consideration (fused search). We have also realized a new search engine and interface by quickly introducing modeling of personal preferences through user networks and visualization of similarities in preferences through user interfaces (personal adaptive search). Use of the search engine and interface enables a completely new search that effectively utilizes the polysemy and ambiguity inherent in multimedia contents.

Research

Thermo-acoustic vibrations are often generated in combustion equipment and combustion gas exhaust systems, leading to noise generation and reduction of the life of combustion equipment. This is caused by acoustic pressure fluctuations linked to heat generation fluctuations in the combustion and exhaust systems, and we are analyzing the physical processes that cause these fluctuations and investigating techniques to suppress them. With this study, a single circular tube is filled with a combustible premixed gas that is ignited at one end, and a thermo-acoustic vibration phenomenon that occurs during flame propagation in the tube is used. Various boundary conditions (open end condition, direction of propagation, composition of the gas mixture, diameter and length of the propagating tube, structure of the flame surface, etc.) are applied to this propagation phenomenon to induce the thermo-acoustic vibration phenomenon, and the factors behind it can then be understood using the combustion instability analysis method. The vibration phenomena reproduced here are observed in a simplified system, but they are general phenomena and lead directly to the understanding of thermo-acoustic vibration phenomena that occur in actual combustion equipment and exhaust systems.

Research

Since conventional avatar-based communication systems are based on one-to-one communication, it is difficult to recognize the position and posture information of each physical person participating in a communication field of three or more people where virtual and real worlds are mixed, and to control the behavior of individual avatars accordingly, while maintaining the integrity of the entire field.
In this research, we have developed an AR communication system that shares the position and posture information of physical people (e.g., smartphone terminals) participating in a communication field through recognition of a common AR target and network linkage between terminals, and reflects this information in the behavior of avatars visible from each terminal. The avatars know who and where the participants are in the communication field, and the avatar changing its pose following the movements on one participant's terminal can be seen by other participants from their own viewpoints.

Research

In this study, we developed a parallel boundary element analysis framework as part of the JST CREST project on “Application Development and Execution Environment with Automatic Tuning Mechanism.” By using this framework, it is possible to develop boundary element analysis programs for large-scale parallel computing systems with a small programming cost. We also developed a library of H-matrices, which approximates dense matrices with less data using low-rank approximation. This library can be used for analysis of N-body problems in addition to boundary element analysis, and is already being used for earthquake simulation on supercomputers. There is no other H-matrix library that supports hybrid parallel processing utilizing multiple threads and processes, and this is a unique feature of this research.

Research

Existing semiconductor devices operate through the electric charge of electrons. In addition to the electric charge, an electron also has the other property of spin, which is a magnetic property. The electron spin in a solid can be aligned in a certain direction (Fig. 1a) or rotated about a specific axis (Fig. 1bc), depending on the situation. The key to realizing next-generation electronic devices is to control such electron spin in semiconductor devices. In this study, we used indium-, gallium-, and arsenic-based field-effect transistors (Fig. 2) and performed electrical measurements in a cryogenic environment (absolute temperature of 20 mK) using a dilution refrigerator (Fig. 3). In this way, we were able to precisely determine for the first time the spin-orbit interaction coefficient, which is necessary to control electron spin (Fig. 4).

Research

Although the human genome has been deciphered and many of the genes have been elucidated, the structure and function of receptors, which play an important role in homeostasis and environmental responses, have not been fully elucidated, because most of them are membrane proteins and their expression levels are low. Many receptors, however, are expected to be major targets for drug discovery in the future because of their functional aspects, and are thought to be the factors that cause individual differences. We are applying machine learning technology to efficiently narrow down compounds that can bind to receptors.

Research

Raman scattering has been used in chemical analysis, physical chemistry, and semiconductor research because it provides information on molecular species and structures without staining. It is also recently actively applied to the biological and medical fields. However, Raman scattering is very weak. We have developed a multifocal coherent Raman scattering microscope with integrated a wavelength-tunable synchronous picosecond laser and realized imaging at 100 frame/s, which is faster than the video rate. We also demonstrated that nerves are visualized without staining and at high speed under a rigid endoscope of 12 mm in diameter and 550 mm in length. It is expected to be a new imaging tool for nerve-sparing endoscopic surgery.

Research

Our dialogue activity calculation system calculates the real-time activity level using information such as the distance between the interactants, voice data, and body movements. By using this activity level, the robot can determine whether it is allowed to enter the dialogue space or interrupt the dialogue, and can take contextually adaptive actions. Furthermore, by having multiple robots act in a way that increases the dialogue activity level for each other's actions, the user's attention (e.g., gaze) can easily be guided. Such a system for generating robot behavior using the level of dialogue activity has not been included in conventional research on social robots, and can be applied to robots at reception desks and home robots for households.

Research

We propose technologies to actively control the sedimentation rate and dispersion behavior by effectively using the collective nature of particles in liquid caused by concentration differences. When suspension conditions change, heterogeneously dispersed particles show collective sedimentation behavior. We aim to understand the behavior of particles near the concentration interface, which is closely associated with such collective behavior, to actively use it to promote sedimentation, control dispersion and improve transport efficiency, all of which are important in various engineering processes.

Research

The purpose of this study is to elucidate the process of cooperation and value creation in a community-type workspace. A community-type workspace is an open workspace where individuals share information and knowledge with other through communication, and create value through collaboration according to the situation. A coworking space is a typical example of such a place, and in recent years, it has been becoming more and more popular in Europe, the U.S., and the rest of the world. In the background, there is a movement of questioning the highly uniform interaction and cooperation among members in closed spaces, a system that is still dominant in organizations and local communities, and to achieve both individual autonomy and solidarity. This research is expected to provide knowledge that will contribute to the design and operation of such workspaces, as well as their organizational and social utilization, which are still largely unknown.

Research

While technology greatly benefits society, it also poses various risks. Therefore, when introducing advanced technology, it is necessary to design governance systems that minimise these risks and to determine the optimal public policies to maximize the benefits.
In the case of automobiles, the perception of the regulatory policy often differs among stakeholders such as manufacturers, regulators, and users. Regulatory policy is also largely determined by harmonized international standards.
As such, I define public policy problems in introducing advanced technology into society based on an understanding of the overall picture, seek a place in which stakeholders can reach an agreement, build consensus, and consider how to create governance systems in which the public and private sectors can cooperate.

Research

Heterogeneous (insoluble) metal catalysts, which are easy to separate from the reaction mixture and have excellent reusability, can be used for organic synthesis in an environmentally-friendly manner. However, compared with the corresponding homogeneous (soluble) catalysts, they have a problem of reduced catalytic activity. We have developed a polystyrene-crosslinked bisphosphine ligand, PS-DPPBz, based on the topological control of polymer chains. Since this ligand is effective in generating highly active monochelate mononuclear transition metal complexes, it has significantly improved the efficiency of Ni-catalyzed reactions such as amination coupling of aryl chlorides and ester-azole coupling. PS-DPPBz can also be used for substrates to which it is difficult to apply existing catalysts. PS-DPPBz can be separated by filtration and reused, so it is expected to use this catalyst for industrial purposes.

Research

Nitrogen in carbon resources (Fuel-N) is emitted as NOx and N2O during combustion. During high-temperature gasification, it is mainly converted to NH3, which becomes a source of NOx in later-stage gas combustion. With this study, we have worked on the development of a method to convert Fuel-N into harmless N2 through a pyrolysis process prior to combustion or gasification, and found that Ca ions supported by the ion-exchange method change into CaO nanoparticles during pyrolysis and catalyze the formation of N2 formation.
We have also found that Fe ions, which are originally contained in lignite coal, and FeOOH, which is abundantly found in brown iron ore, readily become metallic iron nanoparticles during the heating process, and that N2 is selectively produced during the decomposition reaction of NH3, pyridine and pyrrole by this catalyst. Since these N-containing species are contained in the crude gas produced during coal gasification, we are working to develop a new high-temperature gas purification method for the removal of these compounds.

Research

At this laboratory we are using GIS to study the use of geospatial information, such as Geospatial Information Authority (GSI) maps and digital national land information, maintained by the national government as well as open data maintained by local governments and big data such as movement history acquired by GPS. For example, the results of this research are being used to support the formulation of plans for tsunami evacuation in snowy and cold regions. The winter environment in snowy and cold regions (frozen road surfaces, reduced road width due to snow, etc.) makes tsunami evacuation in coastal areas extremely difficult. At our laboratory we generate a lot of information necessary for planning, such as the demarcation of difficult-to-evacuate areas, the estimation of difficult-to-evacuate populations, and evaluation of the capacity of evacuation sites under such snowy cold conditions, and publish our techniques and results. In this way, we are developing technologies to easily and quickly create socially useful information from a geographical perspective, and are continuing our research to contribute to the formation of the foundation for an advanced information society.

Research

For a user to operate a multi-degree-of-freedom robot such as a humanoid robot, it is necessary to remember which commands correspond to which operations, and the more commands there are, the harder it becomes for the user. Since it is usually difficult to prepare a set of commands that are easy to remember and use for all, there is no guarantee that the interface created will be easy to use. With this research, we read the user's intentions through the interaction between the user and the machine, and construct an interface that the user can operate intuitively. As a result, we can develop easy-to-use interfaces that match the characteristics of individual users. We are also applying this technology to the development of an air mouse and air trackball that can be operated without a device by sensing the movement of the hand operating the mouse or trackball.

Research

Concrete is structurally hardened by binding rock (aggregate) through a hydration reaction between cement and water. As a structural material, concrete is intended to withstand loading and certain weather/environmental conditions, but these may cause cracking of the concrete, which may progressively deteriorate due to strong acids and other chemical reactions caused by erosion and materials from the atmosphere, seawater and groundwater that come in contact with it. To stably use the social infrastructure for a long period of time, it is important to be able to see inside the internal structure of concrete with “bug eyes” and find any abnormalities that have occurred.
With the pioneering “non-destructive integrated CT-XRD method,” the sample is irradiated with high-intensity X-rays from synchrotron radiation to selectively visualize 3D structures from transmitted monochromatic X-rays at 25 keV. Energy-dispersive X-ray diffraction is also performed in specific regions of interest through multiple slit operations to identify hydrates (portlandite, calcite, etc.), their alteration and aggregate minerals.

Research

The Gd2Si2O7: Ce (GPS) single crystal scintillator has excellent features such as high luminescence (1.4 times that of NaI:Tl), high energy resolution, non-tidal and no self-radioactivity, and can be used in high temperature environments of 250°C or higher. The technology has been transferred to Oxide Corporation, and is now ready for use in SPECT and other applications. We have also established a stable manufacturing technology for 5 cm square GPS sintered plates. By combining a position sensitive photomultiplier tube, it is now possible to detect nuclear fuel materials emitting alpha rays, which were released in the Fukushima Daiichi Nuclear Power Plant accident, with high sensitivity. The prototype device succeeded in detecting nuclear fuel-induced α-ray-emitting radionuclides in an environment with nuclear fuel-induced α-ray-emitting radionuclides: natural radioactivity (radon progeny) = 1:200, which had been inconceivable with conventional devices.

Research

Anodic oxide film is an artificial passive film formed on the surface of aluminum, and was developed in Japan about 100 years ago. There are many anodized aluminum products around us, but our research group is reviewing the chemical substances and formation methods (anodic oxidation) used to form anodized aluminum surfaces from the ground up, and we try to develop a new anodizing method that exhibits superior properties and innovative functions. Specifically, we are developing anodized aluminum with highly ordered nanostructures, hard anodized aluminum with a Vickers hardness of Hv = 600 or higher, anodized aluminum with high corrosion resistance in acid, base, and chloride environments, and anodized aluminum that shines beautifully by producing luminescence and structural colors.

Research

In this study, we are constructing a mathematical algorithm for biomedical optical imaging based on the radiative transfer equation. Our goal is to develop an imaging technique with excellent image resolution that can be applied to biological tissues and body parts where conventional imaging based on mathematical models cannot be applied. Until now, the numerical computational burden of the radiative transfer equation has been enormous, limiting its applicability to small-sized organisms. In this study, we have succeeded in developing a highly accurate and computationally efficient light propagation model by coupling the radiative transfer equation and the photon diffusion equation. Optical imaging based on the developed light propagation model can be applied to various biological tissues and sites. Currently, we are working on applying the model to the optical diagnosis of thyroid tumors in the human neck and the in-vivo evaluation of optical property values in biological tissues.

Research

We are developing and applying methods for predicting temporal changes in the microstructure of metallic materials during the series of phase transformations that occur in the manufacturing process, such as solidification, grain growth, and diffusional solid transformation. We are specifically engaged in the development of a phase-field model, a method to simulate microstructure formation, and have succeeded in developing a model that calculates the diffusional phase transformation with the highest accuracy in the world. We are also working on microstructure control in various alloy systems by combining experimental approaches, atomistic approaches using molecular dynamics, and information science approaches such as data assimilation and machine learning. We are developing new theories of microstructure formation by using ultra-large scale calculations and obtaining results that lead to optimization of the actual processes.

Research

Research objective: Development of veterinary antibody drugs and protein drugs targeting PD-1 and other immunosuppressive factors and their application to therapeutics. Comparison with and advantage over conventional technology: This approach does not target a specific disease, but rather a wide range of diseases in which the anti-pathogen and anti-tumor effects are lost due to immunosuppressive mechanisms. Since the immunotherapy is based on activated lymphocytes, it is expected to have a multifunctional immune-enhancing effect. Uniqueness of the research: There are limited reports of clinical applications of this approach in the veterinary fields. Characteristics: We will establish therapeutic antibodies for animals and evaluate their effectiveness against various diseases. Efficacy: We aim to provide new treatments for diseases of livestock (cattle, horses, pigs, etc.) and companion animals (dogs, cats, etc.) for which there are no effective vaccines or treatments.

Research

In the polymer electrolyte fuel cell (PEFC), which is a highly efficient and clean energy conversion device, the water produced by the reaction passes through a catalyst layer pores of several tens of nanometers in diameter and is discharged into the gas diffusion layer and gas supply channel through the microporous layer (MPL), which is a porous layer with pores of several micrometers in diameter, as shown in the left figure below. In the activation in a sub-zero environment in cold regions, the produced water freezes, causing the power generation to stop and degrade. However, the phenomenon is on a micro-nano scale and is thus difficult to measure, so the phenomenon is still insufficiently understood. This study is aimed to clarify where the water freezes and what mechanism leads to performance shutdown and aging degradation. We will conduct microscopic observation, electrochemical measurement and catalyst layer model analysis to contribute to the improvement of activation resistance and extension of the service life. The middle figure below shows the catalyst layer filled with ice, and the right figure is a structural schematic of the catalyst layer modeled in the analysis.

Research

This paper focuses on the low thermal conductivity of iron-based materials, which are expected to be used in actual DEMO reactors, with a view to the development of heat exchange devices facing to the plasma in operation, and is aimed at a significant improvement of thermal conductivity, which is considered to be the key to success. The 500°C temperature gradient near the cooling tube of the DEMO reactor divertor imposes a huge heat load that has never been experienced in engineering equipment before. On various iron-based materials (pure iron, reduced activation ferritic martensitic steel and oxide dispersion strengthened ferritic steel), Cu and W wires of high thermal conductivity are appropriately arranged to ensure strength as a structural material while serving as a heat sink.

Research

We are studying the link between stress and disease. Recently, when autoreactive T cells against central nervous system antigens were transferred to mice that had been subjected to chronic stress, the mice suddenly died. The cause of death was heart failure due to hemorrhage in the stomach and duodenum, as found with humans. Stress-specific activation of neural circuits induced microinflammation in the brain, where transferred T cells, etc. were accumulated in specific blood vessels, and a new neural circuit activated by this triggered the gastrointestinal disorder and heart failure. There have been no animal model of stress in which the molecular mechanism has been elucidated, and this model is useful for screening of new drugs for stress-induced diseases. Using this system, we also identified a group of molecules of which the expression is upregulated in specific blood vessels in the brain during stress, and antibodies against these molecules suppressed sudden death. We are also currently identifying marker candidates for autoreactive T cells in humans.

Research

Electrochromism is a general term for compounds that change their color tone in response to changes in external electrical potential. As materials that can undergo reversible color changes, they are attracting attention as light control materials for smart windows and display functions for electronic paper. Materials of which not only the color tone, but also fluorescence, optical rotation (circular dichroism), etc. can be changed, enable tailor-made responses according to the application.
With this technology, we provide a group of substances with multiple responses based on cationic organic dyes of which the color tone can easily be controlled. The reduced species of cationic dyes are generally reactive, and the repeatability of the response is low, but with this technology, the decomposition process of the reduced species is suppressed by incorporating two cationic moieties. The bi-stability of the oxidized and reduced species, in which no exchanges occur, even when they are mixed, makes it possible to apply this technology to high-density recording materials.

Research

In our original definition of “intestinal environment,” three elements, namely, food materials and ingredients, intestinal bacteria acting as parasites, and host Paneth cells α-defensin, determine the “intestinal environment,” and their crosstalk affects health maintenance and disease. This definition has prompted a paradigm shift in food functionality. The purpose of this study is to clarify the involvement of α-defensins in health maintenance, disease development and pathogenesis. This will help us establish a novel functional evaluation system of food and international criteria to evaluate the intestinal environment. By combining a tissue culture system with an α-defensin quantification system, we will lay the foundation for systematic analysis of the relationship between various intestinal functions and food functions of which the mechanisms are still unknown. This will be the first to elucidate immunostimulation and the control of aging substances by digested food materials and ingredients and drugs. We aim to obtain new scientific indicators to create high added value for food.

Research

Combustion phenomena are accompanied by a local temperature rise, which always results in natural convection in the surrounding air . This complicates the phenomena and makes it difficult to understand the fundamentals. In this study, we will utilize the microgravity environment to remove the natural convection and understand the fundamental processes (diffusion, heat conduction, soot formation, ignition, flame propagation, etc.) of combustion phenomena, which will be useful for numerical prediction and modeling of combustion devices. Hokkaido University has an approximately 40-meter drop tower that can be used at any time, making it easy to conduct microgravity experiments, and is also involved in international joint research to conduct microgravity experiments using aircraft and the International Space Station. Thus, we are in a favorable environment to conduct combustion research using the microgravity environment.

Research

The use of the ocean by mankind (e.g., ships and cooling pipes for power plants) is essential, but marine fouling organisms such as barnacles impairs the fuel efficiency of ships and obstructs the functions, for example by clogging. Organotin compounds have been used to prevent functional impairment, but their use has been banned due to their toxicity, and the development of alternatives is desired. We are focusing on compounds used by marine organisms such as nudibranchs to protect against fouling by other organisms. As a result of synthesizing the compounds, we found functional groups (anti-fouling units) that are important for anti-fouling. The functional group was introduced into inexpensive biomass derived from marine organisms in a short process, and when the synthetic product was tested for anti-fouling (cypris larvae of striped barnacles), they were found to have both very strong anti-fouling activity and very weak toxicity. We are currently conducting research on the synthesis of similar compounds and the addition of further functions.

Research

It is essential to eradicate treatment-resistant cancer stem cells to cure cancer. However, their number is small, and it is difficult to isolate and analyze cancer stem cells using conventional methods. With this study, we used a synthetic polymeric hydrogel (Science 344, 161-162, 2014) originally developed by Hokkaido University to induce reprogramming (initialization) of cancer stem cells rapidly, easily, inexpensively, and efficiently, allowing us to analyze the properties of cancer stem cells, evaluate their response to treatment, and predict the properties of cancer cells at the time of recurrence. This technology is expected to make it possible to screen drugs that target cancer stem cells, predict the nature of recurrent tumors that may occur in the future, and administer prophylactic drugs, thereby providing cancer patients with accurate cancer stem cell-targeted precision medicine (preventive preemptive medicine).

Research

It is usually impossible to specify unknowns if their number among observation data is smaller than the number of unknowns that need to be found. However, in case the majority of unknowns are zero, it is sometimes possible to obtain the exact solution. Compressed sensing is a method for obtaining an accurate solution while minimizing the number of observations by using this property. In our laboratory, we are investigating the application of this method to high-precision estimation of the direction of arrival of radio waves as shown in Fig. 1, a method of channel prediction by dividing the incoming wave into elementary waves using this method (Fig. 2), and scatterer detection using the compressed sensing used in radar systems (Fig. 3).

Research

The system estimates the genres and information sources that a user prefers based on the user’s past information browsing history, and assesses the event information that the target user is interested in by referring to the browsing trends of users with similar interests. It also takes into account the geographic characteristics of the user and finally presents the information to him/her. The timing of information distribution is adjusted throughout the system so that the overall system performance can be improved.

Research

Anodizing is a technique used to form oxides with various nanostructures on the surface of metals. We have developed a method to form a large amount of nanofiber oxides with a diameter of sub-10 nm (10 nm or less) by anodizing using a novel electrolyte chemical species. The density of nanofiber formation is extremely high, in the order of 1010 nanofibers (10 billion nanofibers) per cm2. We have found that the metal surface formed with such high-density nanofibers exhibits fast superhydrophilicity of one second or less, as well as superhydrophobicity and superoleophobicity with controlled sliding behavior. It is also possible to mix surfaces with different wettability by using micropatterning techniques.

Research

Conventionally, elastomers have widely been used as soft materials, but in situations where they are used as contact points with living organisms or as their substitutes, hydrophobicity is a critically important factor. Since hydrous materials strongly reflect the physical properties of water, they exhibit physical properties that are very similar to biological tissues. For example, heat transfer and electromagnetic wave absorption properties of hydrous materials are similar to those of living tissues, and their surface friction is as low as that of body tissues. Although gel is the most common hydrophilic soft material, its mechanical strength has been low and its application has thus been limited. We have succeeded in developing a highly strong double network (DN) gel that does not break, even when a truck drives over it, despite 90% water content. This has greatly expanded the possibilities of gel applications. While working to examine the toughness of DN gels, we have discovered the “sacrificial bonding principle,” arriving at the concept of strengthening various materials. In recent years, we have been developing various other types of strong gels besides DN gels.

Research

The glass fiber composite gel we have developed exhibits unbreakable, untearable and tear-resistant properties. Generally speaking, CFRP and glass fiber reinforced plastic (GFRP) are widely used as composite materials. Similar to these fiber-reinforced plastics, fiber-reinforced gels are hard and resistant to tension because of the characteristics of the fibers, while being soft and flexible on bending because of the characteristics of the gel. The self-healing polyampholyte (PA) gel used as the base material is also strong as such thanks to its ability to dissipate a large amount of energy against deformation. Since the gel is flexible, when it is combined with fiber, local distortions can be transmitted through the fiber to the distant base material, resulting in large energy dissipation of the entire material, meaning that it is remarkably strong.

Research

○ For geothermal resource development, which has been actively promoted in recent years, geothermal reservoirs are examined through base structure surveys. We have been investigating the basement structure through gravity surveys, precise seismic source distribution, and seismic velocity structure analysis.
○ For geothermal power generation, steam is produced and hot water is returned to the underground, but it is necessary to monitor the level of the geothermal reservoir to ensure the sustainable use of resources. We will examine the appropriate resource utilization volume through physical assessment of the subsurface fluid conditions using precise gravity measurements and crustal deformation observations.
○ The injection of high-pressure fluids into geothermal wells may induce noticeable tremors and cause problems. We will provide guidelines for appropriate and sustainable resource development by developing a method to evaluate the risk of induced earthquakes based on such parameters as the crustal stress state in the geothermal development area, surrounding faults, the characteristics of the seismic activity, and fluid injection volume.

Research

In conventional solar cells, there is a trade-off between carrier collection and the number of absorbed photons because the photo carrier migration direction and the light travel direction are parallel. Based on the orthogonality between the carrier migration direction and the light travel direction, it was possible to optimize both the light absorption and the carrier collection efficiency. Since the sunlight is sequentially photoelectrically converted from high- to low-energy components over the entire spectrum, thermal dissipation is minimized and high efficiency can be achieved. A waveguide type light collection system with a light wave direction conversion membrane can realize a photovoltaic system that is resistant to diffuse light. By preventing high-energy photons from entering the mid-gap and narrow-gap semiconductors, bond degeneration can be prevented and the life of the device can be extended. It is possible to realize the ultimate concentrator solar cell system, which is strong even in cloudy weather, has high conversion efficiency close to the thermodynamic limit, and is highly reliable.

Research

To accurately obtain the position of a user in a room or a moving object in real time, we have proposed a high-precision time reference point setting method called the phase-matching method (ranging error of 0.03 mm). Based on this technology, we have developed a smartphone users’ gesture recognition system and a robot tracking system. We have also achieved microsecond-order time synchronization using a camera-equipped mobile terminal and an original algorithm. The integration of LED modulation and terminal location information will allow us to distribute location-dependent information and conduct flickerless visible light communication using indoor lighting.

Research

An Al-base alloy with a melting point above 500°C was newly discovered as a latent heat storage material. By skillfully applying chemical conversion/oxidation treatment to the micro-particles of this alloy (approx. 20 μm or larger), we have succeeded in developing core (Al-base alloy) and shell (Al2O3) type latent heat storage microcapsules (Fig. 1). These microcapsules have high heat storage capacity of approximately five times that of solid sensible heat storage materials, and have excellent mechanical properties. Since the shell is made of Al2O3, it can also be treated as a ceramic particle. In other words, it is an epoch-making heat storage material of which the performance can be upgraded while maintaining the current use of ceramic sensible heat storage technology.

Research

We have found that homogeneous palladium nanoparticles can be obtained by treating palladium acetate with potassium tert-butoxide or sodium borohydride in the presence of alkynes (Fig.1). The nanoparticles can be stored in solution for longer than a year and are easy to handle in air. They exhibit excellent performance as hydrogenation catalysts and can efficiently synthesize cis-alkenes (2) and amines (4 and 6) from alkynes (1), organic azide compounds (3) and aromatic nitro compounds (5), respectively. They have excellent cis-alkene selectivity and functional group tolerance (no loss of the ketone, aldehyde, or benzylic hydroxy group, etc.). The catalytic activity is extremely high; the reaction proceeds quickly using only 1/1000 to 1/5000 equivalent of palladium of the substrate (raw material). It also has excellent economic efficiency and convenience, and we are examining the possibility of commercializing it in cooperation with companies.

Research

Hyperpolarized 13C nuclear magnetic resonance imaging (MRI) is a state-of-the-art technique for real-time visualization of metabolic reactions in vivo by temporarily amplifying the MRI signal of any compound labeled with 13C tens of thousands of times. It is expected to be a dream molecular imaging technology that can acquire signals from deep inside the body, which is difficult with optical imaging without radiation exposure like PET/CT.
Cells become cancerous through the accumulation of genetic mutations, and the type of mutation greatly influences the response to cancer therapy. Many cancer-causing mutations are associated with characteristic metabolic changes. Hyperpolarized 13C MRI can be used to non-invasively identify mutated genes in tumors by looking at specific metabolic changes.

Research

The key to the practical application of siRNA is the development of superior delivery technology, but there is still much room for improvement in the delivery efficiency. In addition, from the viewpoint of practicality, it is also important to secure a wide safe therapeutic window. It is also highly desirable to develop platform technologies that can provide appropriate formulations for different purposes without being limited to specific applications. To achieve these goals, we have developed a unique group of pH-sensitive cationic lipids. We achieved the modulation of acid dissociation constants, which is an important factor for the pharmacokinetics of lipid nanoparticles, enabling a target-specific molecular design. The lipid nanoparticles containing the novel lipid CL4H6 induced gene silencing in hepatocytes with world-class efficiency. No significant hepatotoxicity was also observed even after the administration of approximately 3,000-fold higher dose for 50% gene silencing, thus a high level of safety was confirmed. CL4H6 was rapidly degraded and eliminated after siRNA delivery.

Research

Materials that are finely processed on a scale of less than the wavelength of electromagnetic waves can control the reflection and transmission of electromagnetic waves (such materials are known as metamaterials). Mid- to far-infrared radiation, with wavelengths ranging from 3 μm to 1000 μm, can be used for the detection of molecules as it is an electromagnetic wave that is related to heat radiation and can excite molecular vibrations. Since it is a heat-related material, being heat-resistant would render it usable for applications that cannot be realized elsewhere. We are studying process technology for heat-resistant materials with various properties such as metal carbides and oxides, and are measuring the fundamental properties of these materials in the infrared region for application to metamaterial design. By fabricating metamaterials for mid- to far-infrared radiation, we aim to create narrow linewidth mid-infrared light emitting devices for molecular detection and materials for controlling radiation heat.

Research

When ultrasonic waves are emitted from inside a liquid to the surface, the liquid is atomized. The atomized liquid becomes small droplets with a diameter of several micrometers. This liquid atomization technology can produce uniform fine droplets in an energy saving manner and is still widely used in our daily life. Although the mechanism of liquid atomization is still not completely understood, based on our previous research, it has become clear that microbubbles in the vicinity of the liquid surface promote atomization. In this study, we focus on the number of microbubbles in a liquid and aim to control the amount of liquid atomization by ultrasound. By adjusting the number of microbubbles appropriately, we aim to atomize liquids that could not be atomized by ultrasound and to further increase the amount of liquid atomization.

Research

Sialylation (addition of sialic acid) of glycans and glycoconjugates is an important biomarker involved in various biological phenomena such as development, differentiation, disease, infection, and immunity. MALDI (matrix-assisted laser desorption/ionization) is a simple and sensitive soft ionization method. However, the ionization efficiency of unmodified sialic acid-containing glycans is low, and there is a problem that the spectrum becomes complicated due to cleavage of sialic acids or other reasons. With this technique, we succeeded in measuring sialylated glycans and glycoconjugates with high sensitivity and high resolution without undergoing any modification process by improving the addition system to the conventional matrix while suppressing sialic acid desorption. With the change in the cleavage pattern and the increased sensitivity, TOF/TOF analysis and pseudo-MS3 analysis can now be performed using ultra-trace samples. This method does not require chemical modification and separation steps, and enables reaction tracking and rapid sample analysis.

Research

Cellulose synthesized by bacteria and called bacterial cellulose (BC) has unique properties such as high water retention, high strength, biodegradability, and biocompatibility. In recent years, nano-sized cellulose materials (nanofibrillated cellulose (NFC)) has also been attracting attention. In general, NFC is prepared top-down from pulp by physical and chemical treatments, and the resulting NFC is highly dispersed in water. In contrast, by optimizing the culture conditions of cellulose-synthesizing bacteria, it is possible to prepare nanofibrillated BC (NFBC: Fibnano?) from low-molecular biomass in a bottom-up manner. In collaboration with a company in Hokkaido, we have succeeded in the mass production of NFBC (Fibnano?) from molasses, a byproduct of sugar production.

Research

In the field of information science and engineering, many problems appear, such as the problem of designing a mathematical system that provides a desired result, the problem of identifying a mathematical model that gives a given input and output, and the inverse problem of estimating unknown inputs from a system and observations. When dealing with these problems, by dividing the analysis into conditions specific to each problem and mathematical models independent of each problem, it becomes possible to theoretically determine the performance and limitations, and to also expand the analysis horizontally to problems that can be described by similar mathematical models. With this unique approach, we have developed various methodological constructs and application techniques in machine learning problems including image and color restoration, separation of individual sounds in acoustic signals, pattern recognition, and sampling theory. By applying our methodology to today's rapidly developing and diverse measurement technologies, we expect to develop a variety of application techniques based on theory.

Research

In this study, we are using nanoimprinting to pattern typical biomaterials. We hope that the designed micro-/nano-scale shapes can be used to control cell functions and contribute to the development of novel cell culture tools and tissue regeneration.
● Comparison with conventional technology: It is characterized by unprecedented production of regular biomaterial patterns, and is expected to contribute to the discovery of new functions. (*Conventionally, irregular, flat or industrial plastics)
● Effectiveness: Patterning greatly improves the number of cells attached and the degree of elongation compared to flat surfaces. It also makes it easy to align cells in grooves. This can lead to the 3D construction of extracellular matrix (ECM).
● Future vision: We aim to regenerate tissues with a similar structure as that of living organisms by developing patterned materials not only in a flat plane but also in 2.5 and 3 dimensions through further layering.

Research

The hardness test, a method to clarify the strength of materials from the deformation caused by local loading, is widely used based on its high simplicity and reproducibility. To obtain highly accurate stress response information while taking advantage of the simplicity of this method, we have developed in-situ hardness tests (micro-indentation) method.
To observe the surface of the specimen both inside and around the indentation through a transparent indenter during the indentation test, it is necessary to optimize the optical conditions. However, by introducing a liquid with a refractive index close to that of the transparent indenter around the indenter, we have enabled a wide range of surface observations.

Research

The mitochondria-targeted nanocapsules (MITO-Porter) in this study can pass through the cell and mitochondrial membranes to deliver target molecules inside the mitochondria. Conventional technologies using functional elements severely limit the size and type of molecules to be delivered, but the strategy using MITO-Porter, which encapsulates the target molecule, enables mitochondrial delivery independent of the molecular species.
When we prepared MITO-Porter with GFP (green) encapsulated and observed intracellular fluorescence microscopy, we observed many yellow signals that overlap with mitochondria (red), confirming efficient molecular delivery inside the mitochondria. We have also succeeded in introducing genes and nucleic acids into mitochondria, which had been impossible with existing nucleic acid delivery agents (targeting the nucleus and cytoplasm). We are also developing nanocapsules that can be adapted to living organisms.

Research

In this laboratory, we have developed a method to extract the output of renewable energy (RE) power generation hidden in the information of power flowing through distribution lines in real time by applying a signal analysis technique called independent component analysis (ICA). This method enables highly accurate output estimation without having to use preliminary information such as the installed PV capacity in the grid (Fig. 1).
We have also developed a control method to compensate for RE power output fluctuations using storage batteries (Fig. 2) and simulation technology to estimate the storage battery capacity required to suppress output fluctuations for individual wind farms and mega solar power plants.

Research

The world’s first multi-quantum beam HVEM (left)
In 2014, we added an optical system that allows the use of multiple lasers, and developed a multi-quantum beam HVEM that allows in-situ observation at the atomic level under irradiation by multi-quantum beams, including ion, laser and electron beams. We are currently developing an in-situ spectroscopy system.

Nanocrystal growth by UV irradiation (right)
We have succeeded in growing ZnO nanocrystals by irradiating submerged plasma-treated Zn with UV light. We are now promoting research on the growth mechanism and its application.
Scientific Report, 5, 11429(2015), AIP Advances, 7(2017) pp. 035220, Other reference: Nano Letters, 17(2017) pp. 2088-2093

Research

We are not only conducting the world's most advanced artificial intelligence research, but also promoting research in interdisciplinary areas and taking on the challenge of solving real-world problems. Specifically, in medical imaging research, we have collaborated with many medical institutions in Japan to build AI technology that surpasses human diagnostic accuracy. In medical and civil engineering research, we have built Explainable AI (XAI), which not only enables learning of small amounts of data, a challenge in AI research, but also enables explanations of judgment results, making the technology usable in the real world. In recent years, we have also developed human-centric AI technology that can make decisions like humans by introducing information strongly related to human interests, such as human brain activity and eye gaze data, into the AI learning process.

Research

We have fabricated CaYAlO4 single crystals doped with chromium (Cr) and neodymium (Nd) using a technique called the floating zone melting method. By appropriately controlling the fabrication conditions, high-quality red transparent crystals were obtained (Fig. 1). The crystal has a very wide absorption range from the ultraviolet region to the visible region, and shows sufficient absorption even at the wavelength where the energy of sunlight is at its maximum (Fig. 2). We have also found that the absorption is 70 times or more that of conventional materials such as Cr and Nd:YAG. These properties are unique to the newly developed crystal and not found in existing materials. We have also demonstrated that neodymium can emit light upon excitation in the absorption band of chromium due to its fluorescence properties (Fig. 3). Based on this result, it is expected to convert solar energy into laser light with high efficiency.

Research

Until now, chemical reaction phenomena in thermo-fluid (CFD) analysis have been modeled simply by assuming an infinitely fast reaction or an overall reaction model consisting of a few chemical species and reaction equations due to computational load and lack of analysis techniques. On the other hand, when the interaction between chemical reactions and fluid phenomena is important, such as in the case of unsteady phenomenon prediction like the ignition timing of automobile engines or ultra-dilute combustion under extreme conditions, it is difficult to apply simple models. Our research group has solved the problem of applying detailed reaction mechanisms to CFD analysis. The proposed method consists of a time integration method (ERENA) that can significantly reduce the calculation time of chemical reaction equations, and a species bundling technique that combines similar chemical species. Depending on the conditions, the proposed method can be tens to hundreds of times faster than the conventionally used methods while maintaining equivalent accuracy.

Research

To develop a new grout with low environmental load, we focused on minerals produced by living organisms in nature (biominerals), especially CPC, a major component of teeth and bones, and investigated the optimum conditions for CPC precipitation. We also conducted uniaxial compression tests on sand specimens solidified with CPC. In the CPC precipitation test, we have found that the precipitation volume tends to increase as the pH increases from weakly acidic to near neutral. This causes the uniaxial compressive strength of the CPC-solidified sand specimens to reach about 90 kPa, which is within the target range of 50 to 100 kPa for uniaxial compressive strength of sandy soil to prevent liquefaction. Electron microscopy of the specimens showed whisker-like CPC crystals (Fig. 1). These results indicate two possibilities of their usage: chemical grout using self-hardening property and biogrout using pH-dependent precipitation volume.

Research

In terms of the present situation concerning sports, various forms of image and video distribution have spread, and a new environment for watching sports is being established, whereby related data along with images and video footing can be viewed via smartphones and other mobile terminals. However, with soccer, it is only possible to view basic data such as free kick success rate and running distance. This research analyzes various data obtained from users and their surrounding environment to help them understand and visualize the data to accelerate knowledge sharing, even when the relevant knowledge and experience are essential. Examples include ball passing and the degree of dominance. Since the visualization technology of this research can obtain various data surrounding the user and provide various kinds of information in a way that is adaptable to the user's environment, it has high potential for application to the fields of IoT and AI, and is expected to contribute to the creation of new technologies in these fields.

Research

Digital acceleration control (DAC) is a robust control technique for systems with nonlinear terms and modeling errors that are difficult to model. DAC is a very effective controller, but it cannot perform position control by itself because it controls the target acceleration value. Therefore, we have combined DAC with a general PID control system. This PID-DAC combined control system allows both robust position control and acceleration control. In addition, as a new nonlinear compensator that can easily be added to PID controllers without sensors, we propose two controllers: the PID-DA0 control system, which sets the target acceleration value of the control object to zero, and the PID-DJ0 control system, which sets the target acceleration value to zero. Both controllers can easily be added to existing PID controllers without additional sensors, so they have the great advantage of improving system performance sensorless.

Research

The significant drag reduction in turbulent channels due to the addition of a small amount of long-chain polymers or surfactants that form rod micelles in water, is known as Toms effect. A model that simulates polymers with small dumbbell-shaped elements was constructed, and direct numerical simulation (DNS) of turbulent flow in a two-dimensional channel was performed using this model to reproduce Toms effect. It was shown that the discrete element has two mechanisms: one is a resistance reduction mechanism due to the longitudinal vortex damping, and the other is a resistance increasing mechanism due to the additional stress near the wall. Furthermore, by adding the effect of cutting the element to which a strong force is applied, we were able to reproduce the feature that drag reduction occurs in a specific Reynolds number range.

Research

We invite, select and implement proposals for the effective use of stable isotope imaging technology, which is a special feature of the isotope microscope system, to expand it to industrial innovation.
Upon hearing the word, “isotopes,” the concept of “age measurement” immediately comes to mind. Actually, until now, isotope microscopes have been used to analyze isotope ratios, primarily in minerals and other areas of space science. This is a result obtained by observing the as-is cross-section of the obtained sample. However, by changing the concept of the measurement method, we can expand the use of isotope microscopes to industrial application. In other words, by actively doping a target sample with an isotope element, rather than observing it “as such,” it becomes possible to measure the desired imaging we were unable to see before. The use of stable rather than radioactive isotopes also allows us to work safely.

Research

In holographic diversity interferometry, multiple image sensors are arranged in combination with a polarizing optical element to enable precise detection of optical phase distribution in a single measurement without spatial completion error. We have developed an interferometric optical system using two image sensors and have greatly improved the measurement algorithm to achieve highly accurate phase measurement and enable 3D information processing using the measured phase distribution data. This technology can be applied directly to the acquisition of 3D optical information, optical tomography by digital phase conjugation, and 3D optical memory. In this research, we have also succeeded in developing a reference light-free phase detection system that filters the signal light spatially filtered and re-interacts with the signal light. This is expected to find applications in next-generation ultrahigh-speed optical communication systems using spatial modes and in the field of remote sensing.

Research

Advanced composites (carbon fiber composites, carbon fiber reinforced plastics (CFRP)) are widely used as structural materials due to their high specific strength and stiffness. The development of fiber orientation technology has made it possible to arrange fibers not only in straight but also curved lines. Compared with straight fibers, design flexibility is greatly improved, and it is thus possible to produce CFRP components for specific part shapes and uses. In our laboratory, we have been producing composite specimens with curved fibers using a fiber stitching machine (Fig. 1), which is based on embroidery machine technology, to evaluate the mechanical properties of specimens and develop a unique method to optimize fiber shapes. For example, Figure 2 shows the optimum fiber shape to reduce the strain concentration around the holes in a wing model with multiple circular holes, and the strain distribution is shown in Fig. 3. It has been found that the strain concentration is reduced more than with straight fibers.

Research

Cyclic peptides are an ideal molecular form for exploring biologically active compounds (drug discovery) and the design of molecular tools in life science. Cyclization of the peptide backbone can control their conformational stability, orientation, and symmetry. However, peptide cyclization requires specific dilution conditions and complex basic protection strategies. We found that combining a hydrogen-bond-controlled solvent system and a base-free condensation agent system enables the efficient cyclization of poorly soluble peptides under highly concentrated conditions. The simplicity of this technology gives a wide range of applications for drug discovery and life sciences by facilitating the free design and mass production of cyclic peptides.

Research

The transport properties of porous materials such as concrete does not only depend on the porosity, but also on the spatial distribution of each phase. Therefore, the transport properties of HCP, which is a main component of concrete, was predicted. Figure 1 shows a cross section of HCP observed using a backscattered electron image, showing the distribution of each phase. We extracted each phase, calculated the autocorrelation function, and based on the results, distributed each phase in three-dimensional space to construct the three-dimensional spatial image model shown in Fig. 2. Figure 3 shows a comparison of the results of the diffusion coefficient calculated by the finite difference method and the measured values. The estimated and measured values agreed well with each other, even for different samples, indicating that the diffusion coefficients of hardened cement can be predicted using this model.

Research

With the advent of crowdsourcing services in recent years, it has become easy to commission jobs (tasks) to a large number of people via the Internet, and these services are being used in various fields of information science (image recognition, natural language processing, information retrieval, databases, etc.). In crowdsourcing, it is important to check the work quality because not all workers necessarily have the required skills and diligence to work on a task. We have proposed a method to ensure the work quality by asking workers to report their confidence (degree of conviction) in their work results. The technical feature of this method is that it does not trust the confidence rating reported by workers as it is, but performs statistical quality control assuming the existence of over- and under-confident workers.

Research

Since the amount of data handled during image processing is generally huge, it is essential to optimize the system as a whole by combining hardware and software. In this laboratory, we are investigating the configuration of image processing systems by studying image processing algorithms and their implementations complementarily. One of the results of our research is real-time adaptive brightness correction of video images based on the Retinex theory (Fig. 1), which can adaptively correct the brightness of video images taken under conditions of large changes in illumination, such as backlighting, in real time. We are also working on high-quality image smoothing (Fig. 2) based on cost optimization, which is expected to be applied to image processing such as photo illustration, pre-processing of various image processes, brightness correction, and detail enhancement.

Research

We are researching technologies for the automatic recognition and modeling of objects and structures in indoor and outdoor environments from point clouds obtained by ground-based and vehicle-mounted 3D laser scanning systems, as well as basic point cloud data processing methods. The objects to be recognized and modeled include a wide range of arbitrarily shaped objects, rooms, pole-like objects such as utility poles and street lights, trees, road surfaces, and buildings. In addition to the technology of generating mesh models, polygon models, and CAD models from point clouds, we also conduct research on point cloud registration, segmentation, shape feature extraction, machine learning, and procedural object recognition that serves as the foundation for the technology. This technology enables detailed recognition and analysis of the environment and structures, maintenance and management, various simulations and improvement plans using 3D models that faithfully reflect the current state.

Research

In today's internet society, recommendation technology, if it works well, can benefit both the provider and the receiver of the service. A recommendation service is not a one-time event, but an iterative process with feedback each time, and the feedback only concerns the items that are recommended. Therefore, to increase the accuracy of subsequent recommendations, it is not only important to recommend items that the user is likely to like based on the feedback history (knowledge utilization), but also items from which the user is likely to acquire more information (knowledge acquisition). The Bandit method attempts to maximize user satisfaction by balancing the use and acquisition of knowledge. We are developing a recommendation system using this method.

Research

In the study of earthquakes and volcanic activity, the Earth's interior is sometimes estimated by capturing slight movement of the Earth's surface. This movement is called crustal movement, and efforts are still being made to improve the estimation accuracy and quality. Recently, interferometric SAR (SAR interferometry), which uses satellite SAR phase data, has made it possible to detect crustal movement in remote areas and overseas. In the Arctic, there is no so-called crustal movement, but as shown in the figure below, clear ground deformation has been detected in Western Siberia. This can be seen around so-called thermokarst terrain, which is often found in the Arctic, and is thought to represent subsidence of the ground surface due to the thawing of permafrost. Research on the formation process of thermokarst landforms, which has been largely untouched in the past, has just begun, and evaluation of the impact of global warming is an important issue for the future.

Research

The primary purpose of my research is to identify the unique communication phenomena that form within organizations. In my research on pure risk, I explored internal/external organizational public relations, especially as pertaining to product accidents and the internal risk communication in organizations handling hazardous materials. I believe that communication that is created/disturbed/diffused/structured within an organization and that has some kind of inherent meaning/value for the organization will lead to novel organizational strategies, and that is what characterizes my research and makes it unique. In this regard, I have recently been examining how social organizations (e.g., photography) are organized and the intentions of it.

Research

We are proposing spin devices that exceed the current mainstream CMOS devices in terms of performance and power, and are analyzing their performance using condensed matter theory. The main objective of this research is to create power-saving devices that provide superior performance to CMOS devices. To calculate the performance of novel spin devices, quantum field theory and relativity are used to calculate the spin conductivity and other properties. Currently, we are studying topological insulators and skyrmions. Topological insulators are bulk insulators, but spontaneous spin currents flow only on their surfaces. If successfully applied to devices, topological insulators make it possible to fabricate ultra-low power devices because the topological insulator itself is non-dissipative. Skyrmions are also a peculiar vortex generated in magnetic materials, and are expected to play the role of a switch by driving a current.

Research

The quantum key distribution technology has passed the proof‐of‐principle phase, and research is now under way with an eye on its practical application. Since this is a technology to realize the ultimate confidential communication, field tests and other researches on it are conducted worldwide. In our laboratory, we are examining both theoretical and implementation-related aspects on quantum key distribution. In the real world, things do not always go according to the theory, and experimental results sometimes differ from those expected in theory. Our goal is to examine these discrepancies and quantitatively guarantee the security of cryptographic keys produced on real devices. To this end, we are conducting research to fill the gap between the theoretical studies and the actual device development. We believe that this research will open the way to measure and evaluate the behaviors of the actual quantum devices, and finally to realize practical quantum systems, which will contribute to future quantum networks.

Research

The etching process of semiconductor surfaces is one of the essential steps in the fabrication of semiconductor devices such as transistors. In this laboratory, we have developed an etching method that is superior to conventional dry etching methods in terms of both depth control and damage suppression, by utilizing electrochemical oxidation and dissolution reactions on semiconductor surfaces. As a result of applying the method to AlGaN/GaN heterostructures, which are considered to be promising power transistor materials, it was revealed that the etching process can be self-stopped at the desired processing depth by optimizing the electrochemical conditions, thus eliminating the need for an etching stop layer, which had been essential in prior technologies, and enabling precise control of the transistor threshold in a simpler way. In addition, the etched surface by this method has less processing damage than the dry-etched surface, and is expected to be a promising method for improving transistor performance.

Research

Our in-situ electron microscopy system is capable of three-terminal device measurements using two movable probes and a fixed sample holder as electrodes. A MOS transistor is inserted in the sample holder to limit the excess current flow due to stray capacitance.
Microelectronic devices that are almost ready for practical application include devices such as phase-change memory and resistance change memory that can predict structural changes accompanying resistance changes. It is difficult to confirm the mechanism of resistance changes in microdevices due to their high operating speed and nanoscale structure, but this system enables the evaluation of such a mechanism and helps to efficiently investigate the cause of the defective operation and ensure its reliability. By using this system, we can also effectively confirm the operating functions and evaluate the causes of defects in nanostructured functional devices, such as nanomachines and nanostructured secondary batteries, which are expected to be further developed in the future.

Research

As telecommunication devices increase in capacity and become more sophisticated, semiconductor devices are becoming more and more integrated. However, there is concern that cosmic ray neutrons may cause an increase in soft errors, such as bit information upset and operation confusion. Therefore, in collaboration with NTT, we have reproduced soft errors using a compact electron accelerator-driven neutron source to create a place to develop countermeasure technologies in advance. This enables the advance prediction of the failure rate in the natural environment, the detection of errors and verification of operational measures, which will lead to improved reliability of the equipment.
The feature of this technology is the use of a compact accelerator-driven neutron source. In the past, large-scale accelerator-based neutron sources were required, and it was difficult to secure sufficient test time and experimental space. However, through our research, we have demonstrated that it is possible to conduct sufficient tests even in a facility with a neutron intensity of several million times that in nature.

Research

Plasmas generated in liquid are of great interest in the fields of nanotechnology, environmental engineering and medical engineering, but the need for high voltage to generate the plasma can be an obstacle. Meanwhile, in the field of ultrasonic engineering, it is known that the interior of a bubble becomes plasma at the same time as the collapse of acoustic cavitation. Using a very simple method of inserting a perforated metal plate into a liquid where ultrasonic waves are applied, we have succeeded in localizing and efficiently generating acoustic cavitation, which is difficult to fix in position. This has been valued as a unique method of generating plasma in liquid without using high voltage. Currently, we are working to clarify the mechanism of this method and to prepare guidelines for the design of a large-scale device. In the future, we hope to develop various new plasma application technologies.

Research

○ Acoustic perforation (sonoporation) using microbubbles and pulsed ultrasound: Pulsed ultrasound irradiation of microbubbles in contact with the cell membrane enables temporary perforation only at the attachment site (Fig. 1). We have realized a method to deliver drugs or genes into any desired position in the target cell by adding drugs or genes to the microbubbles and controlling the attachment site with optical tweezers.
○ Succeeding with therapeutic site identification and drug delivery by using microbubbles and an ultrasound system: A microbubble, which has the target function of adhering only to the cells to be treated, is injected into a vein. To identify the therapeutic site, the tissue where the bubbles have accumulated is detected using an ultrasound contrast method. Pulsed ultrasound waves are then generated to break the bubbles, allowing temporary perforation of the cell membrane and drug delivery (Fig. 2). By adding drugs or genes to the bubbles, highly efficient drug delivery only to the target cells can be realized.

Research

Optical information processing, transmission, recording and reproduction are performed using the intensity, polarization and spatially uniform phase of laser light. The transmission capacity can be increased through multiplexing using different frequencies. In contrast, the spatial characteristics of light form an unexplored area that has not been actively utilized until now. Based on this background, information multiplexing using Laguerre-Gaussian (LG) light and quantum information processing using the orbital angular momentum (topological charge) that characterizes LG light have been attracting attention as a step to overcome the limitation of information processing capacity. In this study, we have utilized material interaction and realized the mode control of LG light and the conversion and conservation of orbital angular momentum using short-pulsed light, as well as space-division multiplexing fiber transmission.

Research

A large number of nanoparticle-based drugs are currently investigated, including drug delivery system (DDS) carriers, many of their surface is covered with biocompatible poly(ethylene glycol) (PEG). In this regard, we have found that gold nanoparticles (AuNPs) modified with cyclic PEG exhibit high dispersion stability at high salt concentrations. In other words, AuNPs treated with cyclic PEG with a molecular weight of 4000 retained their dispersion stability for one week or longer in a 180 mM NaCl solution, which is a higher concentration than physiological conditions, whereas AuNPs treated with linear PEG of the same molecular weight started aggregating and precipitating within 3 hours in a solution of only 45 mM NaCl. This novel method using cyclic PEG can be applied to a variety of nanoparticle-based drugs including contrast agents and magnetic nanoparticles.

Research

Based on our previous research results, we have discovered that when a droplet hits a solid surface in a condensable gas (not air), splashing is suppressed and a thin liquid film (lamella) spreads on the solid surface at high speed. Since the high-speed lamellae may generate a strong fluid shear force, it seemed possible to use a mixed jet of steam and water to realize an environmentally friendly cleaning method.
Based on our previous research results, we have confirmed that this cleaning method, which uses only water and steam, can achieve the specified cleaning performance for ultra-precision cleaning required in the manufacturing processes of semiconductors, LEDs, and solar cells. This cleaning method is also safe both for the human body and the environment, because it uses only water and steam instead of detergents or other chemicals that are harmful to the human body.

Research

Hokkaido University’s laboratory facilities, where small accelerators are used, have a history of nearly half a century, and are attracting worldwide attention as pioneering facilities. We mainly produce pulsed neutron beams, and the transmission spectra obtained using these beams enable us to map information on crystal structure, microstructure, internal stress and temperature on a two-dimensional real image as a distribution map of the entire sample. We also use X-ray CT which can measure the three-dimensional structure of the inside of an object, and analyze the combined results from neutrons and X-ray studies to synergistically understand the interior information of an object. In the figure, shown as synergistic imaging based on information from neutrons and X-rays, information on elements that cannot be individually obtained is mapped on the inside structure shown on the X-ray CT image. X-ray CT shows the presence of wires in an Al cylinder, but when neutron information is added, we can see that each wire is a different material.

Research

It is expected that superomniphobic surfaces, which do not get wet with water or oil, will possess antifouling and self-cleaning properties. In this study, we have realized a superomniphobic surface that does not only repel water but also octane and other liquids with a surface tension as low as 20 mN m-1, by using a simple wet process for aluminum, which is a practical metal material. This process can also be applied to aluminum foil, which can be used as an antifouling surface in various places. It can also be used as a filter to separate oil and water by controlling its wettability using aluminum mesh.

Research

The introduction of fluorine atoms into organic compounds is very important in the fields of medicine, agrochemicals, and functional materials. There is a method of synthesizing fluorine-containing organic compounds by using fluorine-containing building blocks, but such compounds are still expensive and limited in quantity, and there is a high need for research and development. In this study, we succeeded in synthesizing fluorine-containing aromatic carboxylic acids with various functional groups from readily available fluorine-containing aromatic compounds and carbon dioxide, and achieved good yields using the organic electrolysis method. The fluorine-containing aromatic carboxylic acids synthesized in this study include a variety of new compounds that are difficult to synthesize by conventional methods, and are expected to be used as promising new fluorine-containing building blocks for the synthesis of pharmaceuticals, agrochemicals, and highly functional materials.

Research

Glycan patterns on glycoproteins are important biomarkers because they are factors that determine the disposition of protein in the body. Until now, glycan pattern analysis has required complicated operations such as cutting, chemical modification, and purification of glycans. Mass spectrometry is an ultra-sensitive and high-resolution analytical technique that can directly ionize trace amounts of biomolecules. However, there has not been a method to selectively ionize glycoconjugates such as glycoproteins and glycans in complex macromolecules and mixtures such as body fluids, which requires the complicated pretreatment described above. We have achieved the world's first simultaneous selective cleavage and selective ionization of glycoconjugate glycans, and succeeded in the direct analysis of glycan patterns on glycoproteins. We have also demonstrated that this technique can be used to directly analyze glycan patterns in complex mixtures such as egg white.

Research

Microarray technology is a technology that enables simultaneous comparative analysis of the interaction between a large number of compound libraries with well-defined structures and sequences and sample components. We also have the most advanced technology to design and produce our own carbohydrate compound libraries as molecules for microarray analysis based on our automated carbohydrate synthesis technology. The interaction information possessed by carbohydrates is widely used as biomarkers for in vitro diagnostics, such as blood types, serotypes such as O157, and cancer diagnostic markers (CAxx). In addition, we have succeeded in developing an independently powered mobile analyzer that can be used for online diagnosis, such as analysis of infection patterns associated with mutations in infectious diseases and detailed analysis of vaccine effects, by performing specimen collection and microarray analysis on the spot using a smartphone as a terminal.

Research

Visualization of acoustic wave propagation is extremely useful in the evaluation of physical properties and the design, fabrication and evaluation of functional devices using acoustic waves. For this purpose, we excite surface acoustic waves by irradiating the sample with an ultrashort optical pulse of subpicosecond duration (pump light), and observe their propagation with delayed optical pulse (probe light). Time-resolved two-dimensional images of the acoustic waves are obtained by scanning the delay time and the irradiation position of the probe light. The time resolution is in picoseconds, the spatial resolution is 1μm, and the frequency range is in GHz. Since this method uses a periodic optical pulse train, it was previously only possible to excite and detect acoustic waves at integer multiples of the repetition rate. However, with the newly developed technique, we have realized the excitation and detection of acoustic waves of any frequency. By developing this technique, we have also achieved image vibrations that are completely asynchronous to the repetition frequency of the optical pulse, thereby expanding the range of applications.

Research

Thanks to the development of molecular targeted therapies, antiangiogenic agents are now widely used. However, there are problems such as the lack of companion diagnostics to predict therapeutic effects and side effects due to injury to normal blood vessels.
We have successfully isolated and cultured human tumor vascular endothelial cells and have identified specific markers that they express. Tumor vascular endothelial cells expressing these markers are valuable materials for cell-based screening of novel drugs and compounds, and help us identify new therapeutic targets and drugs that cannot be discovered by studies using conventional tumor cell lines or clinical tumor tissue fragments. Markers expressed by these tumor vascular endothelial cells can also be used as companion diagnostics. This will contribute to the realization of personalized treatment by selecting the target cases as well as the timing and duration of administration with angiogenesis inhibitors.

Research

In a seismically-isolated building, the seismic isolators deform softly during an earthquake, greatly reduce response acceleration in the superstructure and improve the seismic safety. On the other hand, ultimate events such as collisions with retaining walls and buckling or rupture of the seismic isolation bearings may occur for the ground motions exceeding design level caused by a mega earthquake such as the Nankai Trough Mega Earthquake. By using analysis technologies to precisely predict the ultimate behavior of seismically-isolated buildings, it is possible to foresee the occurrence of ultimate events and to consider countermeasures to suppress their occurrence.

Research

We have succeeded in obtaining titanium dioxide thin film on a practical metal substrate such as Cu, Al, Zn and Fe by electrolysis from an aqueous solution containing TiF62- within only a few seconds. The obtained titanium dioxide thin film is anatase crystalline and shows photocatalytic activity without heat treatment. The obtained titanium dioxide thin film is anatase crystalline and shows photocatalytic activity without heat treatment. We have confirmed that it has excellent properties such as decomposition of organic contaminants on the surface by UV irradiation and superhydrophilicity. Since the titanium dioxide film is doped with substrate elements, the development of new functions such as visible light responsiveness can be expected. It can also be deposited on a transparent conductive substrate.

Research

As in Fig. 1, which shows the principle of laser-induced excitation force generation, the laser-induced excitation force is caused by laser ablation. Figure 2 shows an example of the application of this technology, a vacuum environmental excitation measurement system for a membrane structure. This system consists of a YAG-pulsed laser, dielectric multilayer mirror, collecting lens, membrane structure, LDV and vacuum chamber. The membrane structure is fixed inside the vacuum chamber, allowing us to conduct the experiment by adjusting the air pressure inside the chamber from the atmospheric to the vacuum environment. Figure 3 shows the measured frequency response of the membrane. As shown in Fig. 3, with an increase in the vacuum level, the resonance frequency of the membrane becomes higher and at the same time the resonant response level increases. In this way, this technology enables the extraction of both mass effect and damping effect caused by the air on the membrane surface. We have conducted experiments to verify the effectiveness of this technology in a vacuum chamber, which assumes a space environment.

Research