日 時：2018年6月22日（金）16:00～18:00
場 所： 化学本館3階講義室
講演者：山下恵史朗(Keishiro Yamashita)、山下修司(Shuji Yamashita)
講演者：山下恵史朗(Keishiro Yamashita)
Title：Structural analysis of magnesium chloride hydrate under high pressure
contents: Water is a ubiquitous material in the world. Unique properties
of water are ascribed to hydrogen bond (H-bond) between water molecules
(H2O). Bulk water is described as H-bond network composed of H2O
tetrahedral units. The balance of softness and strength of H-bond
network enable the system to take various geometry. Pure water has
various ice polymorphs (at least 18 types) according to P-T condition.
Another important point of water is hydration to electrolytes, which
enable them to exist as active ion. Ions in solution acts in various
fields. In general, Ice (Ih), solid state of water in atmospheric
pressure, repels salts when freezing. Therefore, the system is
considered to be more stable when H2Os construct H-bond network in
crystal rather than they coordinate to ions disturbing the construction
of the H-bond network.
Recently, High pressured ice VII was reported to incorporate a
significant amount of salt in its crystal structure. Then, effects from
the hydration and breakage of H-bond network seem to be comparable under
high pressure. However, the local geometry in the vicinity of
incorporated salt or effects on the physical properties have not been
studied experimentally because of the sparseness of the incorporating
species and coexisting unknown salt hydrates.
In my research, I focused on the structural analysis salt hydrates under
high pressure to directly observe the salt-water mixed system. Salt
hydrate does not contain the randomness as the case of doped system,
which is expected to present information of the interaction and balance
between salt and H-bond network in salt-water mixed system. The in-situ
observation under high pressure is limited so that the information of
the hydrates were little reported. Furthermore, it will enable us to
think about the salt incorporated ice taking into account the
composition and physical properties of coexisting salt hydrates in each
P-T region. Diamond anvil cells (DAC) are used to obtain the single
crystals from salt solution. Their crystal structure was determined from
XRD patterns. I obtained 2 types of single crystal of high pressure salt
hydrate and one’s structure was determined from the pattern except for
hydrogen position but that of the other not. I mainly talk about the
former result comparing the structure at ambient pressure.
講演者：山下修司（Shuji Yamashita)
Title: Imaging analysis of nanoparticles using Laser ablation ICP mass spectrometry in cells of onion
ナノ粒子は同じ組成のバルク体と比べて触媒活性や物性が異なる特徴を持つ。ナノ粒子の応用は医療分野や工業分野など多岐に渡っている一方で、環境動態や生体への影響が懸念されており、安全評価のための分析法の開発が求められている。こうした背景を受け、発表者らはレーザーアブレーションICP質量分析法によるナノ粒子のイメージング分析を検討してきた。これまでの研究から、同じ粒径（40 nm）のナノ粒子でも銀と金では生体内での挙動の違いがあることが判明した。しかし、フェムト秒レーザーを用いたサンプリングではアブレーション時にナノ粒子が破砕されてしまい、信号プロファイルから粒径情報を読み取ることが困難であった。そこで本研究ではナノ秒レーザーであるArFエキシマレーザーを用いることでナノ粒子の破砕を抑え、信号プロファイルからの粒径情報の取得を試みた。本発表ではレーザーアブレーションICP質量分析計で得られるナノ粒子の粒径情報の検討と、細胞中ナノ粒子のイメージング分析の可能性を議論する。