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Alkali Metal Ion Sensing in Aqueous Media by a Dibenzo-16-crown-5 Chromoionophore
Hayashita, Takashi,Kenji, Kunogi,Takagi, Makoto,Lee, Jong Chan,Bartsch, Richard A. 한국분석과학회 1995 분석과학 Vol.8 No.4
A new chromoionophore sym-(decyl)(2-hydroxy-5-nitrobenzyloxy)-dibenzo-16-crown-5 (1) has been synthesized for $Na^+$ photometry in aqueous media. Apparent $pK_a$ values of 1 in the presence of 0.10 M LiCl, NaCl, and KCl were measured by spectrophotometry in 50% 1,4-dioxane-50% water (v/v) and compared with the $pK_a$ of 8.68 in the presence of 0.10 M TMACl. A significant $pK_a$ shift to a lower pH was only observed for $Na^+$ (${\Delta}pH=1.31$) due to selective binding of 1 with $Na^+$. Based upon this $pK_a$ shift, chromoionophore 1 was found to selectively respond to $Na^+$ with a detection limit of $10^{-3}M$ and no interference from $K^+$ up to 0.05 M for detection of 10.0 mM $Na^+$ in 50% 1,4-dioxane-50% water (v/v).
Metal Ion Selectivity of Surface Templated Resins Carrying Phosphate Groups
Murata, Masaharu,Maeda, Mizuo,Takagi, Makoto 한국분석과학회 1995 분석과학 Vol.8 No.4
The metal ion selective resins were prepared by surface template polymerization using monooleyl phosphoric acid (1), oleyl methyl phosphoric acid (2) or oleyl ethyl phosphoric acid (3) as an amphiphilic host surfactant. The $Cu^{2+}$-imprinted resins prepared in the presence of $Cu^{2+}$ adsorbed $Cu^{2+}$ much more effectively than did their reference resins. On the other hand, the $Cu^{2+}$-imprinted resins showed much less binding ability to $Zn^{2+}$. The template-dependent selectivity should be ascribed to a favorable placement of the surface-anchored metallophilic groups for multidentate coordination to specific metal ion.
DNA Ligand - Redox Active Molecule Conjugates as an Electrochemical DNA Probe
Ihara, Toshihiro,Maruo, Voshiyuki,Uto, Yoshihiro,Takenaka, Shigeori,Takagi, Makoto 한국분석과학회 1995 분석과학 Vol.8 No.4
Toward the development of universal, sensitive, and convenient method of DNA (or RNA) detection, two kinds of electrochemically active DNA ligands. acridine - viologen and oligonucleotide - ferrocene conjugate, were prepared. Thermodynamic and electrochemical study revealed that these probes bound strongly to DNA, and showed a typical cyclic voltammograms, indicating a potential for use as a reversible electrochemical labelling agent for DNA. Especially, using the electrochemically active oligonucleotide, we have been able to demonstrate the detection of DNA at femtomole levels by HPLC equipped with ordinary electrochemical detector (ECD). These results lead to the conclusion that the redox-active probes are very useful for the microanalysis of nucleic acid due to the stabilily of the complexes, high detection sensitivity, and wide applicability to the target structures (single- and double strands) and sequences.
Magnetic Memory in a Ceramic YBCO Superconductor Composed of Sub-micron-size Grains
Hiroyuki Deguchi,Takuya Ashida,Mitsuhiro Syudo,Masaki Mito,Seishi Takagi,Makoto Hagiwara,Kuniyuki Koyama 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12
The ceramic YBa2Cu4O8 (YBCO) composed of sub-micron-size grains is considered as a randomJosephson-coupled network of 0 and junctions and shows successive phase transitions. The firsttransition occurs inside each grain at Tc1 = 81 K, and the second transition occurs among thegrains at Tc2 = 47 K. A magnetic glass behavior similar to those of spin-glasses is observed attemperatures below Tc2. The memory phenomena are investigated by recording the zero-fieldcooledand thermoremanent magnetizations measured on heating after the cooling process witha halt at Ts = 41 K. Memory effects of the halt are imprinted in the system when the sampleis re-heated. In the case without a field switch at Ts, the influence of the halt is confined to anarrow temperature region near Ts whereas the memory effect of the halt employing a field switchis extended over a wide temperature region below Ts. The results suggest that chiral-glass orderingoccurs at Tc2 in the ceramic YBCO.
Ishiguro, Masateru,Kuroda, Daisuke,Hanayama, Hidekazu,Takahashi, Jun,Hasegawa, Sunao,Sarugaku, Yuki,Watanabe, Makoto,Imai, Masataka,Goda, Shuhei,Akitaya, Hiroshi,Takagi, Yuhei,Morihana, Kumiko,Honda, IOP Publishing 2015 ASTROPHYSICAL JOURNAL LETTERS - Vol.798 No.2
<P>We report a new observation of the Jupiter family comet 209P/LINEAR during its 2014 return. The comet is recognized as a dust source of a new meteor shower, the May Camelopardalids. 209P/LINEAR was apparently inactive at a heliocentric distance r(h) = 1.6AU and showed weak activity at r(h) <= 1.4AU. We found an active region of <0.001% of the entire nuclear surface during the comet's dormant phase. An edge-on image suggests that particles up to 1 cm in size (with an uncertainty of factor 3-5) were ejected following a differential power-law size distribution with index q = -3.25 +/- 0.10. We derived a mass-loss rate of 2-10 kg s(-1) during the active phase and a total mass of approximate to 5 x 10(7) kg during the 2014 return. The ejection terminal velocity of millimeter- to centimeter-sized particles was 1-4ms(-1), which is comparable to the escape velocity from the nucleus (1.4ms(-1)). These results imply that such large meteoric particles marginally escaped from the highly dormant comet nucleus via the gas drag force only within a few months of the perihelion passage.</P>