Interplanar stiffness in defect-free monocrystalline graphite

The interplanar bond strength in graphite has been identified to be very low owing to the contribution of the van der Waals interaction. However, in this study, we use microscopic picosecond ultrasound to demonstrate that the elastic constant, $C_{33}$, along the $c$ axis of defect-free monocrystalline graphite exceeds 45 GPa, which is higher than reported values by 20\%. Existing theories fail to reproduce this strongly correlated interplanar system, and our results, thus, indicate the necessity for improvement. Since the LDA+U+RPA method, including both random phase approximation correlation and short-range correlation in $p$ Wannier orbitals, shows better agreement with the observation than LDA or even than ACFDT-RPA, the experimental results indicate non-negligible electron correlation effects with respect to both the short-range and long-range interactions.Comment: (Main text) 5 pages, 3 figures, (Supplementary material A) 2 pages, 2 figures, (Supplementary material B) 12 pages, 1 figur

様々な物質とペプチドの複合体におけるナノ・バイオへの応用展開の検討

研究目的：近年、機能性中分子として注目されているペプチド （小タンパク質 を、さらに高機能化、多機能化させることを指向して、生体分子、無機化合物、有機小分子、高分子などと複合させた新規機能性複合体の創製を目的とする。また、これら複合体を用いたナノ分野やバイオ分野への応用展開の検討も行う 。研究概要：これまで分子単体では達成できなかったような高機能・多機能性の材料開発を目指し、無機化合物、有機小分子、高分子とペプチドを複合させた新規機能性複合体を創製する。その創製に際しては、近年、機能性中分子として注目されているペプチドを基に、ある機能を有するペプチドに、糖、核酸、酵素などの生体分子、有機合成小分子、合成高分子、無機化合物などをそれらと結合するペプチドリガンドを介して あるいは共有結合などで 複合させることで、従来以上 に 高機能化、多機能化 させた分子・複合体の創製 をねらう。さらに、本研究で作製できた複合体を用 いて、多段階触媒能を有する材料や、エレクトロニクス材料、特定疾病分子などを高度に検出できる素子、治療に役立つ薬剤などの開発につなげ、ナノ分野、バイオ分野への工学的な応用展開を検討する

One‑, Two‑, and Three-Dimensional Heterospin Complexes Consisting of 4‑(<i>N</i>-<i>tert</i>-Butyloxylamino)pyridine (4NOpy), Dicyanamide Ion (DCA), and 3d Metal Ions: Crystal Structures and Magnetic Properties of [M^II(4NOpy)_<i>x</i>(DCA)_<i>y</i>(CH₃CN)_<i>z</i>]_<i>n</i> (M = Mn, Co, Ni, Cu, Zn)

Solutions of 3d metal ion salts, M­(NO₃)₂, 4-(<i>N</i>-<i>tert</i>-butyloxylamino)­pyridine (<b>4NOpy</b>), and dicyanamide (DCA) in CH₃CN were mixed to afford single crystals of the polymeric complexes [M^II(<b>4NOpy</b>)_<i>x</i>(DCA)_<i>y</i>(CH₃CN)_{<i><b>z</b></i>}]_<i>n</i> (M^II = Mn (<b>1</b>), Co (<b>2</b>), Ni (<b>3</b>), Cu (<b>4a</b> and <b>4b</b>), Zn (<b>5</b>)). X-ray crystallography revealed that the crystal structures are a three-dimensional (3-D) network for <b>1</b>, 2-D networks for <b>2</b>, <b>3</b>, <b>4a</b>, and <b>5</b>, and a 1-D chain for <b>4b</b>. Crystals of <b>2</b>, <b>3</b>, <b>4a</b>, and <b>5</b> contained CH₃CN molecules as crystal solvents, which were readily desorbed in the ambient atmosphere. After desorption of the CH₃CN molecules, the crystal structures of <b>2</b> and <b>3</b> were confirmed to be slightly shrunk without destruction of the crystal lattice. Crystals of <b>2</b>, <b>3</b>, <b>4a</b>, and <b>5</b> after desorption of crystal solvents were used for investigations of the magnetic properties. Complex <b>1</b> showed antiferromagnetic interactions to form a ferrimagnetic chain and exhibited the magnetic behavior of a 2-D (or 3-D) spin-canted antiferromagnet with <i>T</i>_N = 12 K. Complex <b>2</b> containing anisotropic Co^II ions also showed the behavior of a 1-D (or 2-D) spin-canted antiferromagnet with <i>T</i>_N = 6 K. In <b>3</b>, <b>4a</b>, and <b>4b</b>, the aminoxyl of <b>4NOpy</b> ferromagnetically interacted with the metal ion with coupling constants of <i>J</i>_M–NO/<i>k</i>_B = 45, 45, and 43 K, respectively. In <b>5</b>, the magnetic couplings between the aminoxyls in <b>4NOpy</b> through the diamagnetic Zn^II ion were weakly antiferromagntic (<i>J</i>_NO–NO = −1.2 K). DCA might be a weak antiferromagnetic connector for the metal chains

Auditory cortical activity elicited by infrared laser irradiation from the outer ear in Mongolian gerbils.

Infrared neural stimulation has been studied for its potential to replace an electrical stimulation of a cochlear implant. No studies, however, revealed how the technic reliably evoke auditory cortical activities. This research investigated the effects of cochlear laser stimulation from the outer ear on auditory cortex using brain imaging of activity-dependent changes in mitochondrial flavoprotein fluorescence signal. An optic fiber was inserted into the gerbil's ear canal to stimulate the lateral side of the cochlea with an infrared laser. Laser stimulation was found to activate the identified primary auditory cortex. In addition, the temporal profile of the laser-evoked responses was comparable to that of the auditory responses. Our results indicate that infrared laser irradiation from the outer ear has the capacity to evoke, and possibly manipulate, the neural activities of the auditory cortex and may substitute for the present cochlear implants in future

Preparations, Crystal Structures, and Magnetic Properties of <i>N</i>,<i>N</i>-Dipyridylaminoxyl as a New Magnetic Coupler and Its One-Dimensional Cobalt(II) Chains

<i>N</i>,<i>N</i>-Dipyridilaminoxyl, <b>NOpy</b>_<b>2</b>, having a stable aminoxyl, was prepared as a new magnetic coupler for heterospin systems. Solutions of <b>NOpy</b>_<b>2</b> were mixed with those of bis­{1,1,1,5,5,5, hexafluoro-4-(phenylimino)-2-pentanonate}­cobalt derivatives, Co­(hfpip-X)₂, at a 1:1 ratio to afford the polymeric cobalt­(II) complexes, [Co­(hfpip-X)₂(<b>NOpy</b>_<b>2</b>)]_<i>n</i>; X = H (<b>1</b>), F (<b>2</b>), F₃ (<b>3</b>), F₅ (<b>4</b>), Cl (<b>5</b>), Cl₃ (<b>6</b>), Br (<b>7</b>), and I (<b>8</b>) as single crystals. In all complexes, the local structures of the cobalt-complex units were compressed octahedra and the pyridine ligands in <b>NOpy</b>_<b>2</b> units coordinated to the cobalt ions in trans configuration to form linear chains for <b>1</b>–<b>4</b> and in cis configuration to form helical chains for <b>5</b>–<b>8</b>. In the chains, the aminoxyl in <b>NOpy</b>_<b>2</b> ferromagnetically interacted with the cobalt ions to produce the ferromagnetic chains with <i>J</i>_intra/<i>k</i>_B = 9–14 K. In the magnetic susceptibility experiments of aligned sample of <b>6</b>, the magnetic easy axis was determined to be the <i>a</i>* axis, which was the direction perpendicular to the <i>b</i> axis of the chain axis. The resulting chains, all except <b>4</b>, interacted antiferromagnetically among each other, and especially in <b>1</b>, <b>5</b>, <b>7</b>, and <b>8</b>, the magnetic behaviors characteristic to canted two-dimensional (2D) antiferromagnets with <i>T</i>_c = 5.6, 4.0, 4.0, and 6.2 K, respectively, were observed. All complexes showed slow magnetic relaxations affected by the interchain antiferromagnetic interaction. The effective activation barriers, Δ_eff/<i>k</i>_B, for the reorientation of the magnetism for all complexes except <b>4</b> were estimated to be 25–39 K in the presence of a direct current (dc) field