News Article | May 16, 2017
A research team has for the first time successfully measured the electronic states of Rh-Cu alloy nanoparticles (NPs) that exhibit similar catalytic activities at different Rh-to-Cu ratios (by number of atoms). The nanoparticles serve as a catalyst for exhaust gas purification. The results indicated that it is difficult to correlate NPs' electronic states with their catalytic activities. More detailed analysis on the relationship between these two variables may lead to the discovery of new methods of rendering alloy NPs as effective catalytically as pure Rh NPs. These methods may not be based on the matching of alloy NP electronic states with those of pure Rh NPs. The rare element Rh is a promising catalyst for the purification of exhaust gases from automobiles and other sources. However, because Rh is a highly valuable resource, its use needs to be minimized. Kitagawa's group at Kyoto University previously succeeded in synthesizing Rh-Cu alloy NPs, which is impossible to achieve using bulk materials. Nagaoka's group at Oita University confirmed that these alloy NPs are capable of serving as a catalyst for exhaust gas purification by oxidizing exhaust gas components such as CO and NOx. Their catalytic capability was comparable to that of pure Rh NPs, and did not diminish with decreasing Rh content. It had been in general assumed that changing the composition of alloy NPs would also change their electronic states, and that their catalytic activities were closely related to their electronic states. Based on these assumptions, many materials scientists had been interested in studying the electronic states of Rh-Cu alloy NPs. Technical issues made such a study difficult to implement in reality. Recently, Sakata's group at NIMS for the first time measured the electronic states of Rh-Cu alloy NPs at different Rh-to-Cu ratios. It is very difficult to accurately evaluate the electronic states of NPs using photoelectron spectroscopy employing low energy (soft) X-rays. This is because NP surfaces are coated with a protective material to prevent them from clumping together. To overcome this issue, we took photoelectron spectroscopy measurements of the NPs at NIMS's beamline located in the world's largest synchrotron radiation facility (SPring-8). The facility enabled us to collect electronic state data from the entirety of the NPs using high energy (hard) X-rays capable of penetrating the protective outer layer material. We examined the electronic states (oxidation states) of two types of Rh-Cu alloy NPs: NPs with a higher (about 80%) Rh and comparable Rh : Cu (about 50%) content. Similar oxidation states were found in NPs with the higher Rh content and in pure Rh NPs. On the other hand, NPs with the comparable Rh : Cu ratio had a lower proportion of Rh(3-δ)+ in an oxidation state and higher Rh0 than that of the NPs with the higher Rh content and had a higher proportion of Cu2+ in an oxidation state. These results indicate that more detailed evaluations of electron states are vital to the creation of new catalytic and other functional materials. In the future, we plan to carry out a theoretical study on the relationship between NPs' catalytic activities and their electronic states. In addition, to accelerate the creation of new functional materials, we will promote the development of materials informatics by providing our data on the electronic structures and atomic arrangements of alloy NPs and various other materials. This research was supported by the MEXT's Nanotechnology Platform Japan program, and JST's ACCEL project entitled "Creation of innovative functions of intelligent materials on the basis of element strategy" (Professor Hiroshi Kitagawa, research team leader). This study was published in Scientific Reports on January 25, 2017. Explore further: The mystery of why Ag-Rh alloy nanoparticles have a similar property to Pd
News Article | May 19, 2017
The Energy Carriers initiative in Japan is a national project that is specifically looking at ways to efficiently store and transport hydrogen. One way to do this is to use ammonia as a hydrogen source. However, discovery of an efficient process for breaking down ammonia has proved difficult, largely because the catalytic process to break down ammonia requires the continuous addition of heat, which can be prohibitively expensive. Katsutoshi Nagaoka, Takaaki Eboshi, Yuma Takeishi, Ryo Tasaki, Kyoto Honda, Kazuya Imamura, and Katsutoshi Sato of Oita University in Japan have developed a method using a novel catalyst for producing hydrogen from ammonia without the addition of external heat through the catalytic cycle. Their work appears in Science Advances. The decomposition of ammonia into hydrogen and nitrogen is an endothermic process, meaning that it requires the addition of energy to obtain products. This means that traditional catalytic decomposition reactions require the addition of a large amount of heat to obtain a useful amount of hydrogen gas. Nagaoka et al. developed a catalyst that is made of a RuO nanoparticle supported on γ-Al O catalyst bed. After purging their catalyst of H O and CO , ammonia and oxygen were added to the reaction vessel where ammonia was adsorbed onto the catalytic surface, resulting in an increase in temperature. This increase in temperature catalyzed the oxidative decomposition of ammonia, an exothermic process. This heated up the reaction, which in turn, provided the energy for the endothermic decomposition of ammonia into hydrogen and nitrogen. The catalyst pre-treatment did require heating to remove water and carbon dioxide, but it did not require subsequent re-heating. Tests on catalyst cycling showed that after the initial pre-treatment of the RuO /γ-Al O catalyst with helium at 300oC, the catalyst was able to cycle three times and still produce hydrogen in maximum yields. Furthermore, these studies included oxidative passivation to ensure that no heat was produced from oxidation of Ru to RuO . In practice, oxidative passivation will not be necessary. So, even though heating is required to pre-treat the catalyst, heating is not required for additional cycles of the catalyst. In an effort to understand how the RuO /γ-Al O catalyst works, Nagaoka et al. compared the maximum catalytic bed temperature that results from self-heating of RuO / γ-Al O to RuO /La O , a known ammonia decomposition catalyst. They found that the aluminum-based catalyst heated to a maximum temperature of 97oC, while the lanthanum-based catalyst heated to a maximum temperature of 53oC. This is important because the auto-ignition temperature for the oxidative combustion of ammonia is 90oC, and it explains why better reaction yields were seen with RuO / γ-Al O . The authors point out that this difference in adsorption temperature is likely due to the favorable interaction between ammonia, a basic molecule, and Al O , which is a Lewis acid. La O , on the other hand, is a Lewis base. Additionally, the authors looked at the difference between using bare γ-Al O as a catalyst and RuO / γ-Al O . They found that 90% of the ammonia adsorbs onto bare γ-Al2O3 compared to the catalyst bed and the RuO nanoparticle. This implies that ammonia is chemisorbed onto the nanoparticle and γ-Al O , which then promotes multilayer physisorption. Overall, this type of catalyst is helpful in providing enough heat to overcome the needed heat requirements for the endothermic decomposition of ammonia into hydrogen and nitrogen gas. This study shows that self-heating catalysis is a viable option for exploring solutions to the practical difficulties in using ammonia as a hydrogen fuel source. Explore further: Discovery of a facile process for H2 production using ammonia as a carrier More information: Katsutoshi Nagaoka et al. Carbon-free Hproduction from ammonia triggered at room temperature with an acidic RuO/γ-AlOcatalyst, Science Advances (2017). DOI: 10.1126/sciadv.1602747 Abstract Ammonia has been suggested as a carbon-free hydrogen source, but a convenient method for producing hydrogen from ammonia with rapid initiation has not been developed. Ideally, this method would require no external energy input. We demonstrate hydrogen production by exposing ammonia and O2 at room temperature to an acidic RuO2/γ-Al2O3 catalyst. Because adsorption of ammonia onto the catalyst is exothermic, the catalyst bed is rapidly heated to the catalytic ammonia autoignition temperature, and subsequent oxidative decomposition of ammonia produces hydrogen. A differential calorimeter combined with a volumetric gas adsorption analyzer revealed a large quantity of heat evolved both with chemisorption of ammonia onto RuO2 and acidic sites on the γ-Al2O3 and with physisorption of multiple ammonia molecules.
News Article | April 29, 2017
« PNNL, GM team develops design principle for stable silicon anodes for Li-ion batteries | Main | DENSO and IBIDEN to collaborate on next-generation vehicle exhaust systems and vehicle electrification » Researchers at Oita University in Japan have developed an innovative process for the production of hydrogen from ammonia without the need for an external heat source to initiate or maintain the reaction. An open access paper on their work is published in the journal Science Advances. Liquid ammonia (NH ) has been considered as a carrier (storage medium) for hydrogen that could alleviate the challenges of transporting, handling and storing hydrogen for commercial applications. However, the adoption of ammonia as a H carrier, especially for household and transportable devices, has been limited due to the lack of an efficient process for producing H and nitrogen by the oxidative decomposition of ammonia. Conventional production of hydrogen from ammonia by catalytic decomposition is challenging because the endothermic nature of ammonia decomposition requires that the catalyst be continuously heated by an external heat source during the reaction. Typically, the Oita team noted, a high temperature is needed for ammonia decomposition; for example, equilibrium calculations show that a temperature of 400°C is required to convert 99.1% of ammonia to its decomposition products at 0.1 MPa. Heating the catalyst from room temperature to the required reaction temperature using an external heat source takes time and energy. The research team, led by Dr. Katsutoshi Nagaoka and Dr. Katsutoshi Sato, set out to develop a process that could be initiated rapidly, and that could produce H at a high rate without the need for external heat. They found that exposing ammonia and O to a pretreated catalyst consisting of RuO nanoparticles supported on γ-Al O at room temperature (~25°C) triggers the exothermic oxidative decomposition of ammonia, producing hydrogen is produced at a high rate. Before use, the RuO /γ-Al O catalyst is treated under an inert gas (helium) at 300°C to remove H 0 and CO adsorbed on the catalyst, resulting in the formation of ammonia adsorption sites. Upon addition of the mixed ammonia and O to the catalyst at room temperature, ammonia is adsorbed onto the catalyst, thereby generating substantial heat. This heat rapidly increases the catalyst bed temperature to the catalytic autoignition temperature of ammonia combustion, and the oxidative decomposition of ammonia begins. Because the temperature of the catalyst bed during the reaction is higher than 300°C, the adsorbed ammonia is desorbed in situ (self-regeneration of NH adsorption sites). If the catalyst is cooled without exposure to ammonia, then the ammonia adsorption sites remain unoccupied. To reboot the process, the oxidative decomposition of ammonia can be repeatedly triggered from room temperature without heat treatment in an inert gas. This completes a catalytic cycle that requires no external energy source, the team said.
Kyoto University, Oita University and Kyushu University | Date: 2017-07-19
The present invention provides an alloy fine particle including palladium and ruthenium, the alloy fine particle including at least one first phase in which the palladium is more abundant than the ruthenium and at least one second phase in which the ruthenium is more abundant than the palladium, the at least one first phase and the at least one second phase being separated by a phase boundary, the palladium and the ruthenium being distributed in the phase boundary in such a manner that the molar ratio of the palladium and the ruthenium continually changes, a plurality of crystalline structures being present together in the phase boundary.
Ayabo Corporation, Kyushu University and Oita University | Date: 2015-11-18
A guide portion arrangement structure and a guide portion arrangement method arrange a third guide portion in a predetermined position of a drill head for cutting work, thereby stably maintaining an orientation of the drill head and straight movement action of a tip during the cutting. Thus, a favorable surface state of an inner surface of a processed hole can be obtained. The third guide portion is arranged in a position where the effect can be obtained stably and the degree of freedom is high. In a guide portion arrangement structure of a drill head used for cutting work while being supplied with cutting oil, the guide portion contacting an inner surface of a hole of a work piece at an outer periphery of the drill head and receiving a cutting force of a blade portion while maintaining a clearance for passing the cutting oil therethrough, the guide portion includes first to third guide portions arranged on the outer periphery of the drill head. As for a portion of each guide portion that is farthest in a radial direction from the center of rotation of the drill head, it is positioned in an angular range of 80 degrees to 100 degrees about the first guide portion, it is positioned in an angular range of 170 degrees to 190 degrees about the second guide portion, and it is positioned in at least one of an angular range of 1 degree to 34 degrees, an angular range of 146 degrees to 179 degrees and an angular range of 326 degrees to 359 degrees about the third guide portion, on a delay side of the blade portion in the direction of the rotation when a position of a cutting edge of the blade portion is at 0 degree.
Celgene and Oita University | Date: 2016-06-01
A method of identifying a subject having cancer who is likely to be responsive to a treatment compound, comprising administering a treatment compound to a subject having cancer; obtaining a sample from the subject; determining the ratio of a first biomarker level to a second biomarker level in the sample from the subject, wherein at least one of the biomarkers is a CRBN-associated protein; and diagnosing the subject as being likely to be responsive to the treatment compound if the ratio of the biomarker levels in the sample of the subject changes as compared to a reference ratio of the biomarker levels.
Sekisui Chemical Co. and Oita University | Date: 2016-11-02
There is provided a capacitor electrode material that does not require the use of a conductive aid and can increase the capacitance of an electric double layer capacitor. A capacitor electrode material comprising resin-remaining partially exfoliated graphite obtained by pyrolyzing a resin in a composition in which the resin is fixed to graphite or primary exfoliated graphite by grafting or adsorption, the resin-remaining partially exfoliated graphite having a structure in which graphite is partially exfoliated, with part of the resin remaining; and a binder resin.
Sekisui Chemical Co. and Oita University | Date: 2016-01-13
The present invention provides a method for producing a random-structure GIC in which exfoliated graphite having a low regularity of a graphene stacked state and a small number of stacked graphene layers can be easily obtained by exfoliation treatment. The method includes the steps of providing an alkali metal-GIC having an alkali metal intercalated between graphene layers and bringing a polar protic solvent into contact with the alkali metal-GIC in a non-oxidizing atmosphere.
Ji R.-C.,Oita University
Cellular and Molecular Life Sciences | Year: 2012
The lymphatic system provides important functions for tissue fluid homeostasis and immune response. Lymphangiogenesis, the formation of new lymphatics, comprises a series of complex cellular events in vitro or in vivo, e.g., proliferation, differentiation, and sprouting. Recent evidence has implied that macrophages act as a direct structural contributor to lymphatic endothelial walls or secret VEGF-C/-D and VEGF-A to initiate lymphangiogenesis in inflamed or tumor tissues. Bone marrow-derived macrophages are versatile cells that express different functional programs in response to exposure to microenvironmental signals, and can be identified by specific expression of a number of proteins, F4/80, CD11b, and CD68. Several causative factors, e.g., NF-κB, IL-1β, TNF-α, SDF-1, M-CSF, especially TonEBP/ VEGF-C signaling, may be actively involved in macrophage-induced lymphangiogenesis. Alteration of macrophage phenotype and function has a profound effect on the development and progression of inflammation and malignancy, and macrophage depletion for controlling lymphangiogenesis may provide a novel approach for prevention and treatment of lymphaticassociated diseases. © 2011 Springer Basel AG.
Amao Y.,Oita University
ChemCatChem | Year: 2011
Models of photosynthesis mimetic systems, the so-called artificial photosynthesis systems, have been investigated since the 1970s for the purpose of tapping solar energy. With the deterioration of the global environment in the 21st century, attributed to global warming and greenhouse gas emissions, it has become imperative to identify new fuel sources such as solar energy to replace fossil fuels. Among the new fuel production systems, those involving the use of solar energy have attracted attention; examples are systems that produce hydrogen through water photolysis and those that produce methanol by CO 2 reduction with the aid of an artificial photosynthesis system. As hydrogen and methanol are low-carbon fuels (the emission of CO 2 from the combustion of these fuels is low), they are considered to be alternatives to fossil resources. In this review, solar fuel production systems consisting of an artificial photosynthesis system, a catalyst, and an enzyme are discussed. These systems are expected to help in reducing CO 2 and to promote the use of low-carbon fuels in the future. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.