Faculty Profiles - NAKANISHI Kazuki

Synthesis of hierarchically porous MgO monoliths with continuous structure via sol–gel process accompanied by phase separation Reviewed

Xuanming Lu, Kazuyoshi Kanamori, Kazuki Nakanishi

Journal of Sol-Gel Science and Technology Vol. 89 ( 1 ) page： 29 - 36 2019.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer New York LLC

Hierarchically porous magnesium oxide, MgO, monoliths with a well-defined continuous macroporous structure have been synthesized via the sol–gel route accompanied by phase separation. Magnesium chloride hexahydrate was used as a precursor, and propylene oxide was used as an acid scavenger to raise the pH of a reaction solution homogenously. In order to obtain a crack-free monolith after heating in air, poly(vinylpyrrolidone), PVP, was employed as a scaffold of the skeleton as well as a phase separation controller to form the continuous macropores with higher homogeneity. Due to the moderate hydrogen-bonding interaction with magnesium hydroxide, PVP reinforces the gel network essentially composed of fine grained magnesium hydroxide. Even after the removal of all organic components by calcination, the porous gel samples maintained their monolithic form. On the other hand, an additional incorporation of 1,3,5-benzenetricarboxylic acid, H3BTC, was found to be effective in suppressing the oriented growth of the micrometer-sized crystalline phase. The polycrystalline MgO monoliths with specific surface area of 185, 64, and 48 m2 g−1 were prepared after heating at 400, 500, and 600 °C in air, respectively. [Figure not available: see fulltext.]

DOI： 10.1007/s10971-018-4682-2

Sol-gel preparation of hierarchically porous magnesium aluminate (MgAl2O4) spinel monoliths for dye adsorption Reviewed

Uric acid enhances alteplase-mediated thrombolysis as an antioxidant. Reviewed

Kikuchi K, Setoyama K, Tanaka E, Otsuka S, Terashi T, Nakanishi K, Takada S, Sakakima H, Ampawong S, Kawahara KI, Nagasato T, Hosokawa K, Harada Y, Yamamoto M, Kamikokuryo C, Kiyama R, Morioka M, Ito T, Maruyama I, Tancharoen S

Scientific reports Vol. 8 ( 1 ) page： 15844 2018.10

Guo, Xingzhong, Yin, Pengan, Kanamori, Kazuyoshi, Nakanishi, Kazuki, Yang, Hui

Journal of Sol-Gel Science and Technology Vol. 88 ( 1 ) page： 114 - 128 2018.10

The gravitationally unstable gas disk of a starburst galaxy 12 billion years ago Reviewed

Tadaki K., Iono D., Yun M.S., Aretxaga I., Hatsukade B., Hughes D.H., Ikarashi S., Izumi T., Kawabe R., Kohno K., Lee M., Matsuda Y., Nakanishi K., Saito T., Tamura Y., Ueda J., Umehata H., Wilson G.W., Michiyama T., Ando M., Kamieneski P.

Nature Vol. 560 ( 7720 ) page： 613 - 616 2018.8

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Nature

Galaxies in the early Universe that are bright at submillimetre wavelengths (submillimetre-bright galaxies) are forming stars at a rate roughly 1,000 times higher than the Milky Way. A large fraction of the new stars form in the central kiloparsec of the galaxy1–3, a region that is comparable in size to the massive, quiescent galaxies found at the peak of cosmic star-formation history4 and the cores of present-day giant elliptical galaxies. The physical and kinematic properties inside these compact starburst cores are poorly understood because probing them at relevant spatial scales requires extremely high angular resolution. Here we report observations with a linear resolution of 550 parsecs of gas and dust in an unlensed, submillimetre-bright galaxy at a redshift of z = 4.3, when the Universe was less than two billion years old. We resolve the spatial and kinematic structure of the molecular gas inside the heavily dust-obscured core and show that the underlying gas disk is clumpy and rotationally supported (that is, its rotation velocity is larger than the velocity dispersion). Our analysis of the molecular gas mass per unit area suggests that the starburst disk is gravitationally unstable, which implies that the self-gravity of the gas is stronger than the differential rotation of the disk and the internal pressure due to stellar-radiation feedback. As a result of the gravitational instability in the disk, the molecular gas would be consumed by star formation on a timescale of 100 million years, which is comparable to gas depletion times in merging starburst galaxies5.

DOI： 10.1038/s41586-018-0443-1

Synthesis of a hierarchically porous niobium phosphate monolith by a sol-gel method for fructose dehydration to 5-hydroxymethylfurfural Reviewed

On-line Redox Derivatization Liquid Chromatography Using a Carbon Monolithic Column Reviewed

Miyashita Ken, Tanaka Ryo, Hasegawa George, Nakanishi Kazuki, Morioka Kazuhiro, Zeng Hulie, Kato Shungo, Uchiyama Katsumi, Saitoh Kazunori, Shibukawa Masami, Nakajima Hizuru

BUNSEKI KAGAKU Vol. 67 ( 8 ) page： 469 - 478 2018.8

Gao, Da-Ming, Zhao, Bohan, Liu, Haichao, Morisato, Kei, Kanamori, Kazuyoshi, He, Zhiyong, Zeng, Maomao, Wu, Huaping, Chen, Jie, Nakanishi, Kazuki

Catalysis Science & Technology Vol. 8 ( 14 ) page： 3675 - 3685 2018.7

Comprehensive studies on phosphoric acid treatment of porous titania toward titanium phosphate and pyrophosphate monoliths with pore hierarchy and a nanostructured pore surface Reviewed

Zhu Y., Hasegawa G., Kanamori K., Nakanishi K.

Inorganic Chemistry Frontiers Vol. 5 ( 6 ) page： 1397 - 1404 2018.6

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Inorganic Chemistry Frontiers

Simple post-treatments of the porous titania monolith in varied concentrations of phosphoric acid solution provide a series of monolithic titanium phosphates (TiPs) with a hierarchically porous structure together with an exquisite macropore surface. Depending on the reaction conditions, platy crystallites composed of either Ti2O3(H2PO4)2·2H2O, Ti(HPO4)2·H2O (α-TiP), or Ti2O(PO4)2·2H2O (π-TiP) are generated on the macropore skeleton via a dissolution and reprecipitation process, which forms distinct wrinkled surface morphologies. In addition, the treatments effectively suppress the shrinkage during drying, leading to lower bulk density. Post-calcination in air yields porous titanium pyrophosphates preserving the intricate porous architecture in some cases. Notably, the hierarchically porous TiP2O7 monoliths prepared from the α-TiP precursors have a good thermal robustness related to bulk density.

DOI： 10.1039/c8qi00146d

Iron(III) oxyhydroxide and oxide monoliths with controlled multiscale porosity: synthesis and their adsorption performance Reviewed

Hara, Yosuke, Kanamori, Kazuyoshi, Morisato, Kei, Miyamoto, Riichi, Nakanishi, Kazuki

Journal of Materials Chemistry a Vol. 6 ( 19 ) page： 9041 - 9048 2018.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry

Iron(iii) oxyhydroxide and oxide monoliths with controlled multiscale porosity have been successfully fabricated via the sol-gel process accompanied by phase separation. The size of macropores was controlled by synthesis parameters such as starting compositions. The as-dried iron(iii) oxyhydroxide monoliths were amorphous and possessed surface areas over 340 m2 g-1, of which mesostructures could be further controlled by a heat-treatment at 250-350 °C without collapse of macrostructures and monolithic forms. When the as-dried gel was heated at 300 °C, the resultant gel transformed to crystalline α-Fe2O3 and exhibited a specific surface area of 124 m2 g-1. Heat-treatment at 350 °C resulted in the broadened size distribution of mesopores. The adsorption behavior of Congo red has revealed that the interconnected macroporous structure contributed to faster diffusion and better accessibility in a continuous flow-through set up, and the crack-free monolithic forms accounted for an advantageous use of the flow-through adsorbents.

DOI： 10.1039/c8ta01691g

Versatile Double-Cross-Linking Approach to Transparent, Machinable, Supercompressible, Highly Bendable Aerogel Thermal Superinsulators Reviewed

Zu, Guoqing, Kanamori, Kazuyoshi, Shimizu, Taiyo, Zhu, Yang, Maeno, Ayaka, Kaji, Hironori, Nakanishi, Kazuki, Shen, Jun

Chemistry of Materials Vol. 30 ( 8 ) page： 2759 - 2770 2018.4

Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society

A facile yet versatile approach to transparent, highly flexible, machinable, superinsulating organic-inorganic hybrid aerogels is presented. This method involves radical polymerization of a single alkenylalkoxysilane to obtain polyalkenylalkoxysilane, and subsequent hydrolytic polycondensation to afford a homogeneous, doubly cross-linked nanostructure consisting of polysiloxanes and hydrocarbon polymer units. Here we demonstrate that novel aerogels based on polyvinylpolysilsesquioxane (PVPSQ), polyallylpolysilsesquioxane (PAPSQ), polyvinylpolymethylsiloxane (PVPMS), and polyallylpolymethylsiloxane (PAPMS) are facilely prepared via this approach from vinyltrimethoxysilane (VTMS
or vinyltriethoxysilane, VTES), allyltrimethoxysilane (ATMS
or allyltriethoxysilane, ATES), vinylmethyldimethoxysilane (VMDMS), and allylmethyldimethoxysilane (AMDMS), respectively. These aerogels combine low density, uniform nanopores, high transparency, supercompressibility, high bendability, excellent machinability, and thermal superinsulation (λ = 14.5-16.4 mW m-1 K-1). More importantly, transparent, superflexible, superinsulating aerogels are obtained with PVPMS and PAPMS via highly scalable ambient pressure drying without any solvent-exchange and modifications for the first time. This work will open a new way to transparent, highly flexible porous materials, promising in the practical applications of thermal superinsulators, adsorbents, sensors, etc.

DOI： 10.1021/acs.chemmater.8b00563

Transparent, Superflexible Doubly Cross-Linked Polyvinylpolymethylsiloxane Aerogel Superinsulators via Ambient Pressure Drying Reviewed

Zu, Guoqing, Shimizu, Taiyo, Kanamori, Kazuyoshi, Zhu, Yang, Maeno, Ayaka, Kaji, Hironori, Shen, Jun, Nakanishi, Kazuki

Acs Nano Vol. 12 ( 1 ) page： 521 - 532 2018.1

Language：English Publishing type：Research paper (scientific journal) Publisher：American Chemical Society

Aerogels have many attractive properties but are usually costly and mechanically brittle, which always limit their practical applications. While many efforts have been made to reinforce the aerogels, most of the reinforcement efforts sacrifice the transparency or superinsulating properties. Here we report superflexible polyvinylpolymethylsiloxane, (CH2CH(Si(CH3)O2/2))n, aerogels that are facilely prepared from a single precursor vinylmethyldimethoxysilane or vinylmethyldiethoxysilane without organic cross-linkers. The method is based on consecutive processes involving radical polymerization and hydrolytic polycondensation, followed by ultralow-cost, highly scalable, ambient-pressure drying directly from alcohol as a drying medium without any modification or additional solvent exchange. The resulting aerogels and xerogels show a homogeneous, tunable, highly porous, doubly cross-linked nanostructure with the elastic polymethylsiloxane network cross-linked with flexible hydrocarbon chains. An outstanding combination of ultralow cost, high scalability, uniform pore size, high surface area, high transparency, high hydrophobicity, excellent machinability, superflexibility in compression, superflexibility in bending, and superinsulating properties has been achieved in a single aerogel or xerogel. This study represents a significant progress of porous materials and makes the practical applications of transparent flexible aerogel-based superinsulators realistic.

DOI： 10.1021/acsnano.7b07117

On-line redox derivatization liquid chromatography using a carbon monolithic column Reviewed

Miyashita K., Tanaka R., Hasegawa G., Nakanishi K., Morioka K., Zeng H., Kato S., Uchiyama K., Saitoh K., Shibukawa M., Nakajima H.

Bunseki Kagaku Vol. 67 ( 8 ) page： 469 - 478 2018

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Bunseki Kagaku

A macroporous resorcinol-formaldehyde (RF) xerogel was synthesized via sol–gel reaction, accompanied by phase separation; a graphitized carbon monolith was then prepared by calcining the RF xerogel at a relatively low temperature (1200 °C) utilizing catalytic graphitization. The retention behaviors of metal-EDTA complexes on the carbon monolithic column were investigated. The carbon monolith exhibited catalytic activity for redox reactions, like porous graphitic carbon packing materials do; they oxidized Co(II)-EDTA to Co(III)-EDTA during elution. Their redox activity could be modified by treating with an eluent containing an oxidizing or reducing agent. A novel on-line redox derivatization HPLC system using a carbon monolithic column was developed for enhancing the separation selectivity. This on-line redox derivatization HPLC system consisted of two ODS columns as a separation column and one carbon monolithic column as redox derivatization unit placed between them. The Co(II)-EDTA migrated as its original oxidation state in the first ODS column, while it migrated as Co(III)-EDTA in the second ODS column, since Co(II)-EDTA was rapidly oxidized to Co(III)-EDTA in the carbon monolithic column. On the other hand, other metal-EDTA complexes migrated as their original oxidation states in these columns. Therefore, the Co-EDTA could be separated from the other metal-EDTA complexes. This on-line redox derivatization HPLC system was successfully used for determining the trace amount of cobalt in a reference copper alloy.

DOI： 10.2116/bunsekikagaku.67.469

Synthesis and characterization of monolithic ZnAl2O4 spinel with well-defined hierarchical pore structures via a sol-gel route Reviewed

The effect of exercise frequency on neuropathic pain and pain-related cellular reactions in the spinal cord and midbrain in a rat sciatic nerve injury model. Reviewed

Sumizono M, Sakakima H, Otsuka S, Terashi T, Nakanishi K, Ueda K, Takada S, Kikuchi K

Journal of pain research Vol. 11 page： 281 - 291 2018

Guo, Xingzhong, Yin, Pengan, Lei, Wei, Yang, Hui, Kanamori, Kazuyoshi, Nakanishi, Kazuki

Journal of Alloys and Compounds Vol. 727 page： 763 - 770 2017.12

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE SA

Hierarchically porous ZnAl2O4 spinel monolith derived from ionic precursors has been successfully prepared via the sol-gel route accompanied by phase separation in the presence of poly (ethylene oxide) (PEO) and propylene oxide (PO). Appropriate amounts of PEO as a phase-separation inducer and PO as a gelation mediator allow the formation of the xerogel with bicontinuous macrostructure and a monolithic shape. The macropore size of the resultant dried gel is mainly distributed in the range of 0.2-1 mu m, and the whole porosity is about 65%. The dried gel is constructed by crystalline Zn-Al hydrotalcite, becoming amorphous after heat-treated at 300-500 degrees C in air, and is further transformed into single phase ZnAl2O4 spinel with plate-like shape at 600 degrees C. The macroporous structure is well maintained while the porosity increases to 75% and the surface area rises to 109 m(2) g(-1) after heat-treatment. (C) 2017 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.jallcom.2017.08.172

Polymer-assisted shapeable synthesis of porous frameworks consisting of silica nanoparticles with mechanical property tuning Reviewed

Aerogels from Chloromethyltrimethoxysilane and Their Functionalizations Reviewed

Kimura, Tomoki, Shimizu, Taiyo, Kanamori, Kazuyoshi, Maeno, Ayaka, Kaji, Hironori, Nakanishi, Kazuki

Langmuir Vol. 33 ( 48 ) page： 13841 - 13848 2017.12

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

Reactions of "chloromethyltriinethoxysilane (CMTMS) and its derived colloidal network polychlorome-thylsilsesquioxane (PCMSQ) have been investigated to extend the material design strategy toward functionalized and mechanically reinforced aerogels. In a carefully designed sol gel system, CMTMS has afforded transparent aerogels in the presence of cationic surfactant. The surface chloromethyl groups with polarity and reactivity are shown to be useful for supporting nanostructures, with photoluminescent carbon dots (C-dots) prepared from polyethylenimine and citric acid as an example. Furthermore, since nucleophilic substitution (S(N)2) reactions on the surface chloromethyl groups are found to control the equilibrium of formation/dissociation of siloxane bonds, a new gelation strategy triggered by S(N)2 reactions in sol-gel has been developed. In the presence of nucleophilic organic species such as polyamines, a hybrid network consisting of PCMSQ cross-linked with a polyamine nucleophile can be prepared to enhance mechanical properties of aerogel.

DOI： 10.1021/acs.langmuir.7b03013

Sato, Kanako, Ishii, Kanji, Oaki, Yuya, Nakanishi, Kazuki, Imai, Hiroaki

Polymer Journal Vol. 49 ( 12 ) page： 825 - 830 2017.12

Language：English Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

We report the shapeable synthesis of porous silica frameworks using polyacrylamide (PAAm) gel as an organic template and hydrolyzed silicon alkoxide as a silica source. Macroscopically shaped porous frameworks-such as plates, tablets and sheets-comprised of 20- to 40-nm diameter silica particles are obtained via PAAm-silica precursor gels. The mechanical properties (i.e., hardness and Young's modulus) of the silica frameworks depend on the packing density and are controlled by changing the silica content in PAAm gels.

DOI： 10.1038/pj.2017.62

Very Compact Millimeter Sizes for Composite Star-forming/AGN Submillimeter Galaxies Reviewed

Ikarashi S., Caputi K.I., Ohta K., Ivison R.J., Lagos C.D.P., Bisigello L., Hatsukade B., Aretxaga I., Dunlop J.S., Hughes D.H., Iono D., Izumi T., Kashikawa N., Koyama Y., Kawabe R., Kohno K., Motohara K., Nakanishi K., Tamura Y., Umehata H., Wilson G.W., Yabe K., Yun M.S.

Astrophysical Journal Letters Vol. 849 ( 2 ) 2017.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Astrophysical Journal Letters

We report the study of the far-infrared (IR) sizes of submillimeter galaxies (SMGs) in relation to their dustobscured star formation rate (SFR) and active galactic nuclei (AGN) presence, determined using mid-IR photometry. We determined the millimeter-wave (λobs = 1100 μm) sizes of 69 Atacama Large Millimeter/ submillimeter Array (ALMA)-identified SMGs, selected with ≥10 δ confidence on ALMA images (F1100 μm = 1.7-7.4 mJy). We found that all of the SMGs are located above an avoidance region in the sizeflux plane, as expected by the Eddington limit for star formation. In order to understand what drives the different millimeter-wave sizes in SMGs, we investigated the relation between millimeter-wave size and AGN fraction for 25 of our SMGs at z=1-3. We found that the SMGs for which the mid-IR emission is dominated by star formation or AGN have extended millimeter-sizes, with respective median Rc,e = 1.6-0.21+0.34 and 1.5 -0.24+0.93 kpc. Instead, the SMGs for which the mid-IR emission corresponds to star-forming/AGN composites have more compact millimeter-wave sizes, with median Rc,e1.0 -0.20+0.20kpc. The relation between millimeter-wave size and AGN fraction suggests that this size may be related to the evolutionary stage of the SMG. The very compact sizes for composite star-forming/AGN systems could be explained by supermassive black holes growing rapidly during the SMG coalescing, star-formation phase.

DOI： 10.3847/2041-8213/aa9572