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971.
Yoshio Teki Koichi Itoh Atsuhiko Okada Hirokazu Yamakage Tatsuo Kobayashi Kiichi Amaya Sinya Kurokawa Sadaharu Ueno 《Chemical physics letters》1997,270(5-6):573-579
The magnetic properties of N-[(dichlorophenyl)thio]-2,4,6-triarylphenylaminyl radical crystals are reported. The three stable thioaminyls show ferromagnetic behaviors described using the one-dimensional Heisenberg model with the large ferromagnetic interaction of 2J/kB = 28.0, 11.4, and 3.6 K. The other two radicals show the antiferromagnetic alternating chain behaviors with 2J/kB = −16.8 K, = 0.55 and 2J/kB = −128.8 K, = 0.90. The low-temperature susceptibility and heat capacity measurements of the crystal showing 2J/kB = 28.0 K reveal a magnetic phase transition at 0.4 K. The ordered phase shows spin-flop transition which reveals an antiferromagnetic long range order. 相似文献
972.
Hoi Ling Seng Kong Wai Tan Mohd Jamil Maah Wee Tee Tan Hirokazu Hamada Makoto Chikira Chew Hee Ng 《Polyhedron》2009
A set of copper(II) complexes of glycine and methylated glycine derivatives, Cu(aa)2, consisting of C-dimethylglycine, l-alanine, N-dimethylglycine and sarcosine, was investigated for their DNA binding and nucleolytic properties by means of EPR and visible spectroscopy, and electrophoresis. They bind weakly to DNA with apparent binding constants in the range 1.8–2.9 × 103 M−1 with very similar orientation. No DNA cleavage is observed in the absence of exogenous agents. Copper(II) complexes of N-methylated derivatives bind to DNA more stereo-specifically and less strongly, and their oxidative DNA cleavage is less efficient than those of the corresponding C-methylated derivatives in the presence of hydrogen peroxide (H2O2) alone, or sodium ascorbate (NaHA) alone or tandem H2O2–NaHA. The oxidative DNA cleavage mechanism in the three systems involves a common copper(I) species. Neocuproine can inhibit DNA cleavage by these complexes. 相似文献
973.
An algebraic approach based on quantifier elimination is proposed for the inference of probabilistic parameters over stochastic
Lindenmayer systems with interaction, IL-systems. We are concerned with a multi-cellular organism as an instance of a stochastic
IL system. The organism starts with one or a few cells, and develops different types of cells with distinct functions. We
have constructed a simple model with cell-type order conservation and have assessed conditions for high cell-type diversity.
This model is based on the stochastic IL-system for three types of cells. The cell-type order conservation corresponds to
interaction terms in the IL-system. In our model, we have successfully inferred algebraic relations between the probabilities
for cell-type diversity by using a symbolic method, quantifier elimination (QE). Surprisingly, three modes for the proliferation
and transition rates emerged for various ratios of the initial cells to the developed cells. Furthermore, we have found that
the high cell-type diversity pattern originates from the cell-type order conservation. Thus, QE has yielded analysis of the
IL-system, which has revealed that, during the developing process of multi-cellular organisms, complex but explicit relations
exist between cell-type diversity patterns and developmental rates.
相似文献
974.
Aptamer-based fluorescence detection of platelet-derived growth factor (PDGF) on a functionalized diamond surface was demonstrated. In this work, a sandwich design based on the ability of PDGF to bind with aptamers at its two available binding sites was employed. It was found that this sandwich design approach significantly increases the fluorescence signal intensity, and thereby a very low detection limit of 4 pM was achieved. The effect of the ionic strength of MgCl(2) buffer solution was also investigated, and the most favourable binding for PDGF-BB occurred at a Mg(2+) concentration of 5.5 mM. Since the aptamers bind to the target PDGF with high affinity, fluorescence detection exhibited high selectivity towards different biomolecules. The high reproducibility of detection was confirmed by performing three cycles of measurements over a period of three days. 相似文献
975.
Hirokazu Matsunaga 《Tetrahedron letters》2009,50(20):2334-47
Aromatic aldehydes and ketones react with ketene under Lewis acid catalysis to produce β-lactones, which in situ react with another molecule of ketene to produce 3-arylglutaric anhydrides. The mechanism, scope, and limitation of this one-pot synthesis of 3-substituted glutaric anhydrides are discussed. 相似文献
976.
Ken-ichi Shimokawa Katsuhiko Saegusa Fumiyoshi Ishii 《Colloids and surfaces. B, Biointerfaces》2009,74(1):56-58
The influences of various salts and water-soluble polymers on the phase transition temperature of thermo-setting gels prepared by combining methylcellulose (MC)–sodium citrate (SC)–polyethylene glycol (PEG) at appropriate ratios (the MC–SC–PEG system) were investigated. Concerning cations, comparison of the phase transition temperature between SC and tripotassium citrate (PC) showed a rapid increase in the viscosity of SC between 20 °C and 25 °C and an increase in the viscosity of PC between 30 °C and 35 °C. Concerning the valency of anions, comparisons among SC, disodium tartrate dihydrate (ST), disodium maleate hemihydrates (SM), and sodium sulfate (SS) showed a rapid increase in the viscosity of trivalent SC between 20 °C and 25 °C and changes in the viscosity of the three bivalent sodium salts (ST, SM, and SS) at ≥30 °C. Thus the phase transition temperature decreased with an increase in the valency of anions.Subsequently, the influences of various water-soluble polymers on the gelling temperature were compared. Using polyvinylpyrrolidone (PVP) instead of PEG, the gelling temperature decreased with an increase in the PVP concentration even without the addition of SC. Unlike PVP, the addition of xanthan gum as a viscosity-increasing polysaccharide did not reduce the gelling temperature irrespective of its concentration.Temperature-associated changes in viscosity were observed at a fixed SC concentration with changes in the concentration of PVP or PEG. The gel phase transition temperature increased from 46 °C to 50 °C in gels not containing PVP or PEG. The viscosity did not differ between the addition of PVP or PEG at a low concentration and its absence. However, the viscosity clearly changed after the addition of each agent at a high concentration. 相似文献
977.
Ryuhei Nakamura Dr. Kazuyuki Ishii Prof. Dr. Kazuhito Hashimoto Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(9):1606-1608
Shewanella is an electrogenic microbe that has significant content of c type cytochromes (ca. 0.5 mM ). This feature allows the optical absorption spectra of the cell‐membrane‐associated proteins to be monitored in vivo in the course of extracellular respiratory electron‐transfer reactions. The results show significant differences to those obtained in vitro with purified proteins.
978.
Chen JM Lee JM Chou TL Chen SA Huang SW Jeng HT Lu KT Chen TH Liang YC Chen SW Chuang WT Sheu HS Hiraoka N Ishii H Tsuei KD Huang E Lin CM Yang TJ 《The Journal of chemical physics》2010,133(15):154510
Variations in the electronic structure and structural distortion in multiferroic DyMnO(3) were probed by synchrotron x-ray diffraction, lifetime-broadening-suppressed x-ray absorption spectroscopy (XAS), and ab initio electronic structure calculations. The refined x-ray diffraction data enabled an observation of a diminished local Jahn-Teller distortion of Mn sites within MnO(6) octahedra in DyMnO(3) on applying the hydrostatic pressure. The intensity of the white line in Mn K-edge x-ray absorption spectra of DyMnO(3) progressively increased with the increasing pressure. With the increasing hydrostatic pressure, the absorption threshold of an Mn K-edge spectra of DyMnO(3) shifted toward a greater energy, whereas the pre-edge line slightly shifted to a smaller energy. We provide the spectral evidence for the pressure-induced bandwidth broadening for manganites. The intensity enhancement of the white line in Mn K-edge spectra is attributed to a diminished Jahn-Teller distortion of MnO(6) octahedra in compressed DyMnO(3). A comparison of the pressure-dependent XAS spectra with the ab initio electronic structure calculations and full calculations of multiple scattering using the code FDMNES shows the satisfactory agreement between experimental and calculated Mn K-edge spectra. 相似文献
979.
Junichi Ishii Aya Takata Rikio Yokota Masatoshi Hasegawa 《European Polymer Journal》2010,46(4):681-3503
The mechanism of negative coefficient of thermal expansion (CTE) generation for non-stretched polyimide (PI) films is proposed in this work. Negative CTE behavior was observed in some miscible binary blend films composed of a major fraction of a rod-like semi-crystalline PI derived from pyromellitic dianhydride (PMDA) with p-phenylenediamine (PDA) and flexible PIs based on 2,3,3′,4′-biphenyltetracarboxylic dianhydride (a-BPDA) whereas homo PMDA/PDA PI film shows a considerably low but a positive CTE value. The results suggest that the negative CTE generation is related to not only a considerably high extent of in-plane orientation of the PMDA/PDA chains but also to the crystallinity of the blends. The present work revealed that some other PIs, a poly(ester imide), and a polybenzoxazole system also display negative CTE and these systems also possess extremely high extents of in-plane chain orientation without exception. In addition to CTE, the morphologies were monitored as a function of imidization temperature for two PI systems, PMDA/2,2′-bis(trifluoromethyl)benzidine and PMDA/m-tolidine by wide-angle X-ray diffraction, FT-IR spectroscopy, birefringence, and film density measurements. The results suggested that the negative CTE phenomenon occurs when PI films possess very high extents of in-plane orientation and a less crystalline morphology simultaneously, thereby significant thermal expansion can be allowed to the thickness direction. 相似文献
980.
Choi JH Maeda K Nagai K Harada E Kawade M Hirai H Kawagishi H 《Organic letters》2010,12(21):5012-5015
Five fatty acid amides, termitomycamides A to E (1 to 5), were isolated from the giant edible mushroom Termitomyces titanicus. The structures of 1-5 were determined by the interpretation of spectral data and/or synthesis. Compounds 2 and 5 showed protective activity against endoplasmic reticulum stress-dependent cell death. 相似文献