- 1. No Poverty
- 2. Zero Hunger
- 3. Good Health and Well-being
- 4. Quality Education
- 5. Gender Equality
- 6. Clean Water and Sanitation
- 7. Affordable and Clean Energy
- 8. Decent Work and Economic Growth
- 9. Industry, Innovation and Infrastructure
- 10. Reduced Inequality
- 11. Sustainable Cities and Communities
- 12. Responsible Consumption and Production
- 13. Climate Action
- 14. Life Below Water
- 15. Life on Land
- 16. Peace and Justice Strong Institutions
- 17. Partnerships to achieve the Goal
7. Affordable and Clean Energy: 38
- 1. No Poverty
- 2. Zero Hunger
- 3. Good Health and Well-being
- 4. Quality Education
- 5. Gender Equality
- 6. Clean Water and Sanitation
- 7. Affordable and Clean Energy
- 8. Decent Work and Economic Growth
- 9. Industry, Innovation and Infrastructure
- 10. Reduced Inequality
- 11. Sustainable Cities and Communities
- 12. Responsible Consumption and Production
- 13. Climate Action
- 14. Life Below Water
- 15. Life on Land
- 16. Peace and Justice Strong Institutions
- 17. Partnerships to achieve the Goal
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Uncovering the relationships among air pollution (aerosols, PM2.5), wildfires, snow and ice, and climate change in the Arctic and cryosphere for a sustainable society in the future!
An atmospheric scientist working in the Arctic and cryosphere, tackling wildfires, air quality, snow and ice, and climate change
I am conducting a wide range of research on wildfires and their air quality (aerosols and PM2.5), including analysis and prediction of the factors that cause them and impact assessment (climate, health, economy, etc.), using various research methods from observation to data analysis and modeling.
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Figure 1b from Yasunari et al. (2018, Sci. Rep.). Daily mean PM2.5 concentration on July 25, 2014, calculated using NASA's MERRA-2 reanalysis data. The white circle indicates the location of Sapporo City.
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A commercial version of the PM2.5 measurement system for cold regions, updated from the prototype in Yasunari et al. (2022, J. Environ. Manage.). Anyone can purchase it from Tanaka Co., Ltd. (http://kktanaka.co.jp/products; the iron box and the low-cost PM2.5 sensor must be obtained separately)
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A climate (atmospheric circulation) pattern that can likely cause co-occurrences of European heatwaves and wildfires in Siberia and subarctic North America (Alaska and Canada), as discovered in Yasunari et al. (2021, Environ. Res. Lett.): the pattern was named the circum-Arctic wave (CAW) pattern because it is a pattern in which anticyclonic circulation is arranged to surround the Arctic. The figure is from Figure 9 of the paper (created by the current “Science Manga Studio Co., Ltd.”: https://www.sciencemanga.jp/).
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In Yasunari et al. (2024, Atmos. Sci. Lett.), the authors used the commercial PM2.5 measurement system for cold regions and, for the first time, performed the local ambient air quality observation (i.e., PM2.5 measurement) in Qaanaaq, northwest Greenland, in the summer of 2022. They also captured the worsened air quality during the local open waste burning (the figure is the Graphic Abstract of the paper).
Research
In recent years, we have been hearing more and more news about wildfires. Large-scale wildfires can transport air pollution (PM2.5) not only to the area where they occur but also to areas downwind, potentially affecting the people who live there. For this reason, it is necessary to identify the causes of wildfires and the atmospheric aerosols (air pollution) they produce and assess the diverse effects (such as climate, health, social and economic) that follow. In addition, it is extremely important to predict these effects based on the knowledge gained from the perspective of taking measures for people living in the downwind area from where the fires occur. To achieve the above objectives, we have developed a portable PM2.5 measurement system for cold regions, conducting multi-location observations of air quality such as PM2.5, analyzing large-scale global data (satellite, model, re-analysis data, etc.), and conducting research using various methods such as machine learning prediction (we are also conducting joint research with NASA and interdisciplinary research).
Teppei J. Yasunari Specially Appointed Associate ProfessorPh.D. in the field of Earth System Science -
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Equipment for Simultaneous Optimization of Quality and Quantity of Liquid Ice for Freshness Preservation
Liquid ice optimization system for long-term freshness preservation of food
We have developed a device that calculates the minimum required amount of food-grade liquid ice (slurry ice (salt water ice) or salt-free water ice) using a simple heat capacity calculation, and that also calculates the salt concentration, water/ice mixing ratio, and shelf life to determine the slurry ice temperature based on the overall heat transfer coefficient (container heat radiation parameter) of the storage container.
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.
Naoto Tsubouchi Associate Professor -
A method to evaluate radio wave propagation characteristics of in-vehicle wireless access services by large-scale electromagnetic field analysis
Toward optimal design of wireless environments
We have conducted research in various fields where radio waves are applied, including the evaluation of complex and special propagation environments in airplanes and passenger railroad cars, internal exposure of the human body to radio waves, electromagnetic interference evaluation and mechanism estimation regarding body medical devices implanted in the body, and evaluation of electromagnetic field leakage in wireless power supply devices for electric vehicles.
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.
Takashi Hikage Associate Professor -
All-solid-state Lithium Secondary Battery with an Inorganic Solid Electrolyte
Preparation of sulfide solid electrolyte from the liquid phase
We have successfully deposited sulfide solid electrolyte through a simple process of dissolving sulfide glass, which exhibits high lithium ion conductivity in an organic solvent, and drying the glass. We have also found that this method is applicable to coating of electrode-active materials.
Research
In all-solid-state lithium secondary batteries that use a lithium-ion conductive solid electrolyte, the construction of a good electrode-electrolyte interface is very important to realize high energy-density batteries. We have conducted this research to construct a good electrode-electrolyte interface by preparing sulfide solid electrolytes from the liquid phase. We prepared a homogeneous solution of Li2S-P2S5-based solid electrolytes by dissolving them in N-methylformamide (NMF), and successfully redepositing Li2S-P2S5-based solid electrolytes by removing NMF from the solution. This solution was mixed with LiCoO2, a cathode material, and solid electrolyte was coated on LiCoO2 by removing NMF. Using this solution, we produced an electrode composite. Then, using the obtained electrode composite and sulfide inorganic solid electrolyte, we successfully produced all-solid-state lithium batteries and confirmed the stable operation of the batteries.
Kiyoharu Tadanaga Professor -
Analysis of Thermo-acoustic Vibration Generated by Combustion Equipment
Thermo-acoustic vibrations often occur in combustion devices and combustion gas exhaust systems, causing noise and reducing the life of the combustion devices. This is caused by acoustic pressure fluctuations coupled with heat generation fluctuations in combustion and exhaust systems. With this study, we analyze this physical process and investigate the suppression technology.
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.
Osamu Fujita Professor -
Detoxification and Removal of Nitrogen from Carbon Resources Using Nanoparticles
Use of nanoparticles for fuel nitrogen pre-removal and high-temperature gas purification
To establish principles for advanced utilization of carbon resources in harmony with the global environment is one of the most important research themes for the next generation. With this study, we aim to develop a catalytic process that can efficiently convert carbon resources into clean energy using nanoscale metal and metal oxide particles.
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.Naoto Tsubouchi Associate Professor -
Development of Gd?Si?O?-based High-performance Scintillators and Their Application
Development of high luminescence scintillators for radiation detectors
Scintillators are materials that emit light by radiation and are used in medical diagnostic equipment, and for oil exploration and other purposes. Gd2Si2O7 (GPS) scintillators have excellent features such as high luminescence, high energy resolution and non-tidal dissolution, and can be made into single crystals, ceramic plates and powders.
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.
Junichi H. Kaneko Associate Professor -
Development of Polymer Electrolyte Fuel Cells with Excellent Sub-zero Start-up Performance
Elucidation of micro-nano freezing phenomena in fuel cells
We are visualizing the freezing phenomenon near the reaction layer in fuel cells, which cannot normally be observed, using an ultracold electron microscope. By combining electrochemical measurements, we are also elucidating the freezing phenomenon of produced water, which becomes a problem in cold climate applications, and are developing fuel cells with excellent sub-zero activation performance.
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.
Yutaka Tabe Professor -
Development of Structural Materials for Fusion and High Energy Reactors
Iron-based composites with high thermal conductivity
By appropriately arranging high thermal conductive materials in iron-based structural materials, the thermal conductivity of the entire structural materials can be dramatically improved. This will lead to the improvement of the efficiency of energy production and the reduction of radioactive waste, as well as the development of iron-based structural materials for fusion reactors and high energy reactor divertors, for which there has been no solution so far.
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.
Naoyuki Hashimoto Professor -
Electrochemically Responsive Organic Dyes
From electrochromism to multiple responses (fluorescence, circularity)
Based on cationic organic dyes, which allow easy control of color tone, we offer a group of materials that can respond in multiple ways, including fluorescence and optical rotation (circular dichroism). This technology is designed to suppress the decomposition process of reduced species, and the bi-stability of oxidized and reduced species is such that exchange does not occur, even when they are mixed.
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.Takanori Suzuki Professor -
Elucidation of Combustion Phenomena Using Microgravity Fields
Combustion phenomena are accompanied by a local temperature rise, which always results in natural convection in the surrounding air . This complicates the phenomenon and makes it difficult to fundamentally understand it. In this study, we will try to understand the combustion phenomena from a fundamental standpoint by utilizing the microgravity environment to remove the natural convection.
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.
Osamu Fujita Professor -
Fire-safety Improvement Technology for Lithium-ion Batteries
The use of lithium-ion batteries has been expanding rapidly due to their high energy density. On the other hand, since organic solvents are used in lithium-ion batteries, it is important to ensure their fire safety. With this study, we focus on the combustion phenomenon of organic solvents and study combustion inhibition technology.
Research
The use of lithium-ion batteries has been expanding rapidly due to their high energy density. On the other hand, since organic solvents are used in the battery electrolyte, it is important to ensure their fire safety. With this study, we intend to develop a method to quantify the effect of adding a combustion inhibitor to suppress the combustion of organic solvents, search for additives that are effective in suppressing combustion, and study the effect of the lithium salt contained in the electrolyte itself on the flammability of organic solvents. We also conduct modeling and numerical analysis of fire phenomena taking the elementary reaction kinetics of combustion in an electrolyte into consideration.
Osamu Fujita Professor -
Geothermal Resource Monitoring and Risk Assessment of Induced Earthquakes
Monitoring and risk assessment of geothermal resources through geophysical observations
Evaluation of the subsurface structure necessary for geothermal resource development by gravity survey and precise determination of the seismic source. Monitoring of geothermal reservoir resources by precise gravity measurements and crustal deformation observations. Risk assessment of induced earthquakes associated with geothermal well development and research on seismic activity prediction.
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.Hiroaki Takahashi Professor -
High-efficiency Semiconductor Solar Cells
New-type solar cell consisting of a multi-striped semiconductor with orthogonal photon-photocarriers that was coupled to a waveguide.
Temperature rise and device degradation are suppressed by simultaneous optimization of light absorption and photocarrier collection, as well as photoelectric conversion over the entire solar spectrum by multiple semiconductor stripes. This leads to the realization of a highly efficient 2-dimensional PhotoReceptoConversion Scheme (2DPRCS).
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.
Akira Ishibashi Professor -
High-temperature Latent Heat Storage Microcapsules
Core (alloy latent heat storage material) ? shell (Al2O3) type latent heat storage microcapsules capable of high-density heat storage in the high temperature range of over 500?C
The latent heat storage method, which utilizes latent heat generated during the solid-liquid phase change, is attractive for its high-density heat storage capacity. Microencapsulation of latent heat storage material enables not only heat storage but also heat transport and heat control applications, and we have developed latent heat storage microcapsules that can be used in the high temperature range of over 500°C.
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.
Takahiro Nomura Associate Professor -
Infrared Metamaterials Produced by Microfabrication of High Temperature Resistant Materials
Development of materials and devices that manipulate mid- to far-infrared radiation
It is expected that it will be possible to make devices to control corresponding electromagnetic waves by creating heaters and diffraction gratings with patterns smaller than the mid- to far-infrared wavelengths. We are developing methods to fabricate thin films, stacks, and microstructures of metal carbides and oxides, and are studying their elemental characteristics.
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.
Toshihiro Shimada Professor -
Low-power A/D Converters for Sensing
Use of time to digital converter for A/D converter and its low power consumption
Single-Slope A/D converters, which involve the simplest configuration, are used in various forms (image sensors, etc.). However, one drawback is their slow conversion speed. With this technique high speed and low power consumption can be achieved simultaneously.
Research
Single-Slope A/D converters convert analog values to time and then digitize them. By using the Time to Digital Converter (TDC), the conversion time can be greatly reduced. However, power consumption increases significantly. Intermittent operation of the TDC is effective to reduce the power consumption of the TDC part by a factor of several times ten, enabling both high speed and low power consumption. The features of this method are as follows:
Realization of low-power, high-speed, small-area A/D converters
・Synchronization and consistency of two measurements with high precision and coarse accuracy are guaranteed in principle
・The A/D conversion characteristics are continuous and easy to correct.Masayuki Ikebe Professor -
Low-temperature Nitridation Method Using Sodium Amide
Nitride and oxynitride synthesis without using ammonia gas cylinder
This is a method used to convert oxides and other materials into nitrides and oxynitrides at low temperatures (300°C or less) by using a sodium amide melt to trigger a reaction with a highly concentrated and active nitrogen source. Nitrides and oxynitrides can be synthesized without having to prepare toxic ammonia gas cylinders.
Research
This is a new method for nitridation of oxides at low temperatures (300℃ or less). Conventional nitridation methods require the installation of toxic ammonia gas cylinders and toxic ammonia gas recovery facilities, and also use a large amount of ammonia due to the low ammonia gas usage rate. With the present method, the use of sodium amide as a flux minimizes the use of toxic ammonia and makes it possible to obtain oxynitride and nitride nanocrystals at low temperatures. Since sodium amide is a solid nitrogen source, it eliminates the need to install ammonia liquid cylinders. We have also discovered a method to synthesize oxynitrides by mixing chloride and sodium amide through an instantaneous temperature-programmed reaction.
Akira Miura Associate Professor -
MALDI Matrix for Sensitive and High-Resolution Structural Analysis of Unmodified Sialylated Glycans and Glycoconjugates
We have developed a matrix that can ionize sialylated glycans and glycoconjugates without modifying the carboxylic acid moiety of the sialic acids, and can analyze them with high sensitivity and resolution (reflector mode) without desorption of the sialic acid residue.
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.
Hiroshi Hinou Professor ProfessorPh.D. -
Monitoring the Output of Renewable Energy Generation and Measures Against Output Fluctuations
Real-time monitoring of fluctuations in solar and wind power output and control of such fluctuations
We have developed a method for extracting load power (A) and renewable energy output (B) from power flow information in which (A) and (B) coexist. Although (B) fluctuates greatly depending on the weather conditions, we have developed a control method to suppress fluctuations using storage batteries and a method to evaluate storage battery capacity.
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.Hiroyuki Kita Professor -
Multi -beam Ultra-high Voltage Electron Microscope and Materials Research
Multi-beam science and engineering applications
At the High-Voltage Electron Microscope (HVEM) Laboratory of Hokkaido University, the world’s first multi -quantum beam HVEM has been developed. It enables in-situ observation of microstructural changes on an atomic scale using multi-quantum beam irradiation.
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. 2088-2093Tamaki Shibayama Professor -
New Crystal Material Converts Sunlight into Laser Light
New Cr, Nd co-doped crystals for high efficiency solar-pumped lasers
The Nd:CaYAlO4 crystal exhibits a wide absorption band in the visible region and a large absorption cross section. Since the energy absorbed by chromium is transferred to neodymium, it is expected to convert solar energy to laser light with high efficiency.
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.
Mikio Higuchi Specially Appointed Associate Professor -
New Developments in Combustion Reaction Fluid Simulation
Proposal of a highly efficient analysis method that enables the application of detailed reaction mechanisms
We are proposing a numerical analysis technique to efficiently incorporate detailed large-scale reaction mechanisms, such as those of hydrocarbon fuels that consist of hundreds of chemical species and thousands of chemical reaction orders, into thermo-fluid simulations.
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.
Hiroshi Terashima Associate Professor -
Numerical Simulation of Flow and Heat Transfer
Modeling and Simulation of Turbulent Drag Reduction Flow by Surfactant
Modeling and simulation of turbulent drag reduction is performed by adding a surfactant to clarify the resistance-reducing mechanism. Simultaneously, heat transfer analysis is performed to investigate the flow and heat transfer characteristics in detail.
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.
Akiyoshi Kuroda Associate Professor -
Open Advanced Research Facilities Initiative (Project for Creation of Research Platforms and Sharing of Advanced Research Infrastructure)
Microscopic imaging platform for atoms and molecules
Promotion and expansion of the isotope microscope system installed at the Equipment Management Center for shared use by industry, academia and government.
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.Hisayoshi Yurimoto Professor -
Production of High-purity Sodium
Recycling of sodium resources by electrorefining
There is a sodium-sulfur rechargeable battery that is mainly used for industrial applications. In this research, I am developing a recovery process of metallic sodium from inside of used batteries, and produce high-purity sodium by electrorefining.
Research
This research is for the development of a process of the purification of metallic sodium containing impurities by electrorefining. Metallic sodium from used sodium-sulfur batteries is used as a source material. By placing the metallic sodium in the upper left (anode) of an electrolysis cell model (Fig. 1) and applying current, the sodium ions dissolve in the electrolyte and only the sodium is deposited on the high-purity sodium (cathode) layer on the upper right. This process can be operated at 200°C or less. The high-purity sodium obtained by this electrolysis is pure enough to be used as a raw material for batteries and growth medium of semiconductor crystal. Since Japan is dependent on foreign countries for sodium resources, we believe that this technology will be widely applied in the future.
Mikito Ueda Professor -
Real-time Video Processing Technology
Algorithm development and its hardware implementation
In this laboratory, we are promoting research and development of various image processing algorithms and their real-time implementation, focusing mainly on image smoothing and brightness correction of video images, which are recently increasing in capacity (high resolution and high frame rate).
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.
Hiroshi Tsutsui Associate Professor -
Research on Biomass Utilization as a Socio-Technical Systems
Aiming to spread bioenergy through local circulation
At the Laboratory of Sustainable Material Cycle Systems research is conducted on the development of technologies and social systems (socio-technical systems) to create locally distributed bioenergy from biomass such as food waste, sewage sludge, livestock manure, forest residues and rice straw.
Research
We are proposing a system (e.g., planning, modeling and evaluation based on experiments and field studies) that can contribute to both the environment and regional development (economy) by linking energy recovered from biomass (e.g., food waste, sewage sludge, livestock manure, forest residues, and rice straw) through combustion and methane fermentation with local energy consumers (e.g., public facilities, nursing and welfare facilities, agricultural facilities such as greenhouses and food factories). Furthermore, by obtaining cooperation from private companies, we are conducting research on creation of community through biomass utilization in collaboration with the endowed laboratory of biomass community planning (Visiting Professor Toru Furuichi, Specially Appointed Assistant Professor Satoru Ochiai, https://smcs.eng.hokudai.ac.jp/bio-com-p.html).
Kazuei Ishii Professor -
Search for Novel Spintronic Devices and Theoretical Study of the Energy Spectrum of Low-dimensional Electron Gas
Toward power-saving devices
We use condensed matter theory to study materials and structures called topological insulators and skyrmions of which the topology dominates the phenomena. At the same time, we are studying to propose and realize novel spin devices using these topological insulators and skyrmions in the process.
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.
Kenji Kondo Associate Professor -
Sonoplasma Generator
A method to generate acoustic cavitation in a fixed location with high efficiency
Upon the collapse of acoustic cavitation driven by ultrasonic waves in water, the bubble becomes hot and pressure inside increases, turning to plasma (sonoplasma). We have found a way to generate acoustic cavitation in a fixed location with high efficiency, and are working to develop it as a plasma application technology.
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.
Koichi Sasaki Professor -
Stable and Practical Oxide Thermoelectric Conversion Materials
As a result of replacing the sodium ions in the layered cobalt oxide with barium ions of heavier atomic mass, only the thermal conductivity decreased while the electrical properties remained unchanged. We have found that the thermoelectric figure of merit ZT reaches 0.11 at room temperature.
Research
Thermoelectric conversion has been attracting attention as a technology to recycle waste heat. Metal chalcogenides are known as thermoelectric materials, but they have thermal and chemical stability and toxicity issues. Layered cobalt oxides are stable at high temperatures and in air, but have the problems that thermal conductivity is high and conversion performance is low. The research group considered the strategy shown in Fig. 1 to reduce the thermal conductivity of layered cobalt oxide AxCoO2. Figure 2 summarizes the thermoelectric properties in the direction parallel to the layers of Ax-substituted AxCoO2 thin films measured at room temperature. The thermal conductivity shows a monotonically decreasing trend with increasing Ax atomic weight. The room temperature thermoelectric figure of merit of Ba1/3CoO2 is 0.11. The figure of merit ZT increases with increasing temperature. By further enhancing the thermoelectric conversion performance, it is expected to realize stable and practical thermoelectric conversion materials.
Hiromichi Ohta ProfessorPh.D -
Steam/Water Mixture Spray Cleaning Method with an Ultra-low Impact on the Environment
An ultraprecise and safe cleaning method making use of the physical action of steam and water and no chemicals.
We have developed an innovative cleaning method using a completely new vapor-water multiphase spray method, whereby water and steam are mixed and sprayed at high speed from a nozzle. This method is especially notable for not using any chemicals and minimizing the burden on the environment.
We have confirmed that the specified performance can be achieved with ultra-precision cleaning during semiconductor manufacturing processes, etc.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.Masao Watanabe Professor -
Superomniphobic Aluminum
Simple production of antifouling surfaces through a wet process
We have successfully fabricated a micro/nano-hierarchical surface morphology through chemical etching/anodization of aluminum sheets and meshes. By coating the surface with a fluoroalkyl monolayer, we have also succeeded in obtaining a surface that is not wetted by almost any liquids, including oil.
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.
Hiroki Habazaki Professor -
Synthesis of Fluorinated Aromatic Carboxylic Acids
Using electricity to make useful carboxylic acids from carbon dioxide
We have succeeded in regioselectively synthesizing a variety of fluorine-containing aromatic carboxylic acids, which are promising as new fluorine-containing building blocks, from readily available aromatic compounds containing several fluorine atoms and carbon dioxide, and achieved good yields by organic electrolysis.
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.
Hisanori Senboku Associate Professor -
Time-resolved Two-dimensional Surface Acoustic Wave Imaging
Excitation and detection of arbitrary frequency response by optical pulse train with fixed period
This technique visualizes the propagation of surface acoustic waves up to the GHz frequency range as a time-resolved two-dimensional image. Conventional methods involve the problem of low frequency resolution, but this method can excite and detect acoustic waves of any frequency.
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.
Osamu Matsuda Professor -
Ultra-rapid Deposition of Photocatalytic Crystalline Titanium Dioxide Thin Films
Ultra-rapid electrochemical deposition technology that does not require high temperature heat treatment
Crystalline titanium dioxide is a practically important oxide as a photocatalyst. We have developed a technology to form crystalline titanium dioxide thin films, which generally require heat treatment at high temperatures, on various metal substrates within only a few seconds using an electrochemical deposition method in aqueous solution.
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.
Hiroki Habazaki Professor -
Use of Lignin, a Wood Component, as an Electronic Device Material
Molding of lignin and its conversion to a functional material
Lignin is second only to cellulose in availability, but the only way to effectively use lignin at present is to burn it for energy production. We are currently working on molding lignin into fibers and films for use as electrodes and separators in electric double-layer capacitors (EDLCs).
Research
EDLCs are electronic devices that are attracting attention as next-generation storage batteries that can replace rechargeable batteries such as Li-ion batteries. The parts called electrodes and separators in EDLCs are made from polymeric materials, so we are conducting research on replacing these polymers with lignin, a major component of woody biomass. By forming lignin into microfibers through electrospinning and converting them into active carbon fibers, we have succeeded in producing the large surface area required for electrode materials. This has led to the production of electrodes with high energy and power densities. In addition, by converting lignin into a flexible polyester film, it became possible to prepare a material that exhibits the same performance as conventional separators. We are currently endeavoring to further improve the performance.
Yasumitsu Uraki Professor -
Web Ground Club, which is a cloud-based geothermal heat pump design and performance prediction program, and Japan's Nationwide 3D Grid Strata Database
It can also calculate the effect of multi-layered ground and groundwater flow and incidental cooling towers.
About 10 years ago, we developed Ground Club (GC), a design and performance prediction tool for geothermal heat pump systems (GSHP), and distributed about 150 of these. We have also released an advanced version called Ground Club Cloud (GCC) for cloud computing on a trial basis, and developed a 3D geological properties database for the entire Japan and implemented it in GCC.
Katsunori Nagano Professor