Comparative pore structure analysis of highly porous graphene monoliths treated at different temperatures with adsorption of N-2 at 77.4 K and of Ar at 87.3 K and 77.4 K

We prepared nanoporous graphene monolith of different porosity by high temperature treatment up to 2073 K in Ar. The porosity is comparatively evaluated with N-2 adsorption isotherms at 77.4 K and Ar adsorption isotherms at 87.3 K and 77.4 K. N-2 adsorption at 77.4 K shows an excess adsorption amount below 3 x 10(-3) of the relative pressure which is caused by the quadrupole moment of an N-2 molecule. This effect doesn't give significant influence on the determination of the total surface area from subtracting pore effect (SPE) method, the micropore volume from Dubinin-Radushkevich (DR) method and the total pore volumes from the Gurvitch rule. However, the peak of the micropore size distribution determined by Horvath-Kawazoe (HK) method from N-2 adsorption at 77.4 K shifts to a smaller size than that from Ar adsorption at 87.3 K by 0.05-0.09 nm. (C) 2015 Elsevier Inc. All rights reserved.ArticleMICROPOROUS AND MESOPOROUS MATERIALS. 209:72-78 (2015)journal articl

Robust graphene-based monoliths of homogeneous ultramicroporosity

Graphite oxide (GO) and graphene monoliths were prepared using the unidirectional freezing of GO water suspension. These materials were saturated with a poly(ammonium-4-styrene sulfonate) water soluble polymer and then carbonized at 1123 K. This process increases significantly the materials strength and density. A uniform deposition of the polymer-derived carbon on the external layers of the graphene sheets of the monolith was found. The carbon from polymer not only provided more contact between the graphene sheets but also apparently increased the overall graphitization level (based on Raman spectra). The modification decreased the electrical resistance by one order of magnitude compared to that of the graphene monolith. N-2 adsorption at 77 K showed that the thus-treated graphene monoliths have quite homogenous pores with the pore width of 0.7 nm. These pores, combined with large transport pores, and conductive properties make the monoliths tested the promising materials for separation, energy storage, and/or gas sensing. The tunability of the properties and pore structure of the robust graphene ultramicroporous monolith through the control of chemistry of the initial GO monolith was shown. (C) 2015 Elsevier Ltd. All rights reserved.ArticleCARBON. 87:87-97 (2015)journal articl

H4K20 monomethylation inhibition causes loss of genomic integrity in mouse preimplantation embryos

Maintaining genomic integrity in mammalian early embryos, which are deficient in DNA damage repair, is critical for normal preimplantation and subsequent development. Abnormalities in DNA damage repair in preimplantation embryos can cause not only developmental arrest, but also diseases such as congenital disorders and cancers. Histone H4 lysine 20 monomethylation (H4K20me1) is involved in DNA damage repair and regulation of gene expression. However, little is known about the role of H4K20me1 during mouse preimplantation development. In this study, we revealed that H4K20me1 mediated by SETD8 is involved in maintaining genomic integrity. H4K20me1 was present throughout preimplantation development. In addition, reduction in the level of H4K20me1 by inhibition of SETD8 activity or a dominant-negative mutant of histone H4 resulted in developmental arrest at the S/G2 phase and excessive accumulation of DNA double-strand breaks. Together, our results suggest that H4K20me1, a type of epigenetic modification, is associated with the maintenance of genomic integrity and is essential for preimplantation development. A better understanding of the mechanisms involved in maintaining genome integrity during preimplantation development could contribute to advances in reproductive medicine and technology

ストレートに着目した空振りに影響を与える要因の定量的分析

要旨ありスポーツ統計科学の新たな挑戦原著論

Noticeable Reverse Shift in the Melting Temperatures of Benzene and Carbon Tetrachloride Confined within the Micropores and Mesopores of Hydrophobic Carbons

Carbon aerogels contain both mesopores and micropores. In this study, benzene/CCl4 was adsorbed in the pores of carbon aerogels (both mesopores and micropores) and their phase behaviours were examined using differential scanning calorimetry. The bulk solid benzene melted at 278 K and the melting temperatures of benzene confined inside the mesopores and micropores of carbon aerogels were 258 and 293 K, respectively. Although the melting temperature depression of condensates in mesopores is well known, the observed elevation of the melting temperature for micropores is very limited in the strongly interacted system. Similar melting behaviours were observed for the confined CCl4; depression by 45 K in mesopores and elevation by 48 K in micropores showed about two times the change as compared with that of confined benzene.ArticleADSORPTION SCIENCE & TECHNOLOGY. 31(2-3):145-151 (2013)journal articl

Multiscale Simulation of Photoluminescence Quenching in Phosphorescent OLED Materials

Bimolecular exciton-quenching processes such as triplet–triplet annihilation (TTA) and triplet–polaron quenching play a central role in phosphorescent organic light-emitting diode (PhOLED) device performance and are, therefore, an essential component in computational models. However, the experiments necessary to determine microscopic parameters underlying such processes are complex and the interpretation of their results is not straightforward. Here, a multiscale simulation protocol to treat TTA is presented, in which microscopic parameters are computed with ab initio electronic structure methods. With this protocol, virtual photoluminescence experiments are performed on a prototypical PhOLED emission material consisting of 93 wt% of 4,4ʹ,4ʺ-tris(N-carbazolyl)triphenylamine and 7 wt% of the green phosphorescent dye fac-tris(2-phenylpyridine)iridium. A phenomenological TTA quenching rate of 8.5 × 10$^{-12}$ cm$^{3}$ s$^{-1}$, independent of illumination intensity, is obtained. This value is comparable to experimental results in the low-intensity limit but differs from experimental rates at higher intensities. This discrepancy is attributed to the difficulties in accounting for fast bimolecular quenching during exciton generation in the interpretation of experimental data. This protocol may aid in the experimental determination of TTA rates, as well as provide an order-of-magnitude estimate for device models containing materials for which no experimental data are available

Sol-gel chemistry mediated Zn/Al-based complex dispersant for SWCNT in water without foam formation

We report a bimetallic Zn/Al complex as an efficient inorganic dispersant for SWCNT, synthesized from Zn(CH3COO)(2) and Al(NO3)(3). The Zn/Al complex shows more than four times greater efficiency at dispersing SWCNT than widely used surfactants (CTAB and SDS). Besides remarkable dispersibility, the Zn/Al complex does not foam upon any shaking treatment and it can be used just after quick dissolution of the powdered form, which is a marked advantage over surfactants. The Zn/Al complex, containing amorphous Al(CH3COO)(3) and a complex of Zn2+ and NO3- ions, should have a unique dispersion mechanism, differing from the surfactants. Al(CH3COO)(3) has higher affinity for SWCNT than ions, adsorbing onto its surface in the first layer and attracting Zn2+ and NO3- ions. Charge transfer interactions between the Zn/Al complex and SWCNT, as evidenced by optical absorption spectroscopy, should induce a charge on SWCNT; the zeta potential of such coated SWCNT was +55 mV, indicating a high dispersion stability in aqueous media. Hence, the Zn/Al complex can widen the applications of SWCNT to various technologies such as the transparent and conductive films, as well as high performance composite polymers. (C) 2015 Elsevier Ltd. All rights reserved.ArticleCARBON. 94:518-523 (2015)journal articl

Activation routes for high surface area graphene monoliths from graphene oxide colloids

Graphene monoliths made from graphene oxide colloids by unidirectional freeze-drying method were activated by typical activation processes of CO2 activation, chemical activation using ZnCl2 or H3PO4, and KOH activation. The porosity development of graphene monolith markedly depends on the activation method. The monoliths with highest surface area are obtained by the KOH activation method; only the KOH activation is effective for production of the graphene monolith of which surface area is in the range of 1760–2150 m2 g−1. The mechanism of the porosity development by KOH activation method is proposed. This work provides a promising route for the bottom-up design of pore width-tunable nanoporous carbons.K.K., F.T., T.F., R.C-S, M.T. and M.E. were supported by Exotic Nanocarbons, Japan Regional Innovation Strategy Program by the Excellence, JST. This work was supported by Grant-in-Aid for Scientific Research (A) (24241038) and Concert-Japan project: Efficient Energy Storage and Distribution, JST. D. M., and this study were partially supported by JST CREST “Creation of Innovative Functional Materials with Advanced Properties by Hyper-nano-space Design”

Metal-semiconductor transition like behavior of naphthalene-doped single wall carbon nanotube bundles

Accepted 27 Jun 2014Naphthalene (N) or naphthalene-derivative (ND) adsorption-treatment evidently varies the electrical conductivity of single wall carbon nanotube (SWCNT) bundles over a wide temperature range due to a charge-transfer interaction. The adsorption treatment of SWCNTs with dinitronaphthalene molecules enhances the electrical conductivity of the SWCNT bundles by 50 times. The temperature dependence of the electrical conductivity of N- or ND-adsorbed SWCNT bundles having a superlattice structure suggests metal-semiconductor transition like behavior near 260 K. The ND-adsorbed SWCNT gives a maximum in the logarithm of electrical conductivity vs. T-1. plot, which may occur after the change to a metallic state and be associated with a partial unravelling of the SWCNT bundle due to an evoked librational motion of the moieties of ND with elevation of the temperature.ArticleFARADAY DISCUSSIONS. 173:145-156 (2014)journal articl