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291.
Kensuke Naka Yoshiyuki Tachiyama Akira Ohki Shigeru Maeda 《Journal of polymer science. Part A, Polymer chemistry》1996,34(6):1003-1013
Poly(N,N-dicarboxymethyl)allylamine was synthesized and used as a chelating polymer for Y, Ba, and Cu. Both pH titration and UV curves of the polymer in the presence of each metal ion showed the chelate formations. The clear solution (pH8) containing the polymer and the metal nitrates of Y, Ba, and Cu (1: 2: 3 in molar ratio) was poured into ethanol to precipitate the polymer-metal chelate. The chelate formations of each metal were confirmed by C(DOUBLE BOND)O stretching bonds. Scanning electron microscope (SEM) and face and point analyses by electron probe microanalysis (EPMA) showed that Y, Ba, and Cu elements were uniformly dispersed on a scale greater than 1 μm. The polymer-metal chelate precursor was calcined and sintered to develop the pure superconductor (1, 2, 3) phase. The sintered sample showed superconductivities of Tc(onset) at 92 K and Tc(end) at 88 K and critical current density (Jc) of 165.9 A/cm2. © 1996 John Wiley & Sons, Inc. 相似文献
292.
Komatsu K Kikuchi K Kojima H Urano Y Nagano T 《Journal of the American Chemical Society》2005,127(29):10197-10204
We have developed a series of fluorescent Zn(2+) sensor molecules with distinct affinities for Zn(2+), because biological Zn(2+) concentrations vary over a wide range from sub-nanomolar to millimolar. The new sensors have K(d) values in the range of 10(-8)-10(-4) M, compared with 2.7 nM for ZnAF-2. They do not fluoresce in the presence of other biologically important metal ions such as calcium or magnesium, and they can detect Zn(2+) within 100 ms. In cultured cells, the fluorescence intensity of ZnAF-2 was saturated at low Zn(2+) concentration, while that of ZnAF-3 (K(d) = 0.79 muM) was not saturated even at relatively high Zn(2+) concentrations. In hippocampal slices, we measured synaptic release of Zn(2+) in response to high-potassium-induced depolarization. ZnAF-2 showed similar levels of fluorescence increase in dentate gyrus (DG), CA3 and CA1, which were indistinguishable. However, ZnAF-3 showed a fluorescence increase only in DG. Thus, by using a combination of sensor molecules, it was demonstrated for the first time that a higher Zn(2+) concentration is released in DG than in CA3 or CA1 and that we can easily visualize Zn(2+) concentration over a wide range. We believe that the use of various combinations of ZnAF family members will offer unprecedented versatility for fluorescence-microscopic imaging of Zn(2+) in biological applications. 相似文献
293.
Kensuke Okuda Shigeki Takarada Takashi Hirota Kenji Sasaki 《Journal of heterocyclic chemistry》2015,52(3):780-792
Libraries of tricyclic 2‐substituted 4‐alkylamino‐9‐chloro‐5,6‐dihydropyrimido[5,4‐d]benzazepines and tetracyclic 12‐substituted 8‐chloro‐1,2,5,6‐tetrahydro‐4H‐imidazo[1′,2′:1,6]pyrimido[5,4‐d]benzazepines were synthesized as part of our research to develop new effective antiplatelet drugs. Several alkyl and aryl groups were used as substituents at the 2‐position. Evaluation of the effects of the newly synthesized compounds on collagen‐induced platelet aggregation revealed several promising antiplatelet candidates with potencies superior to aspirin. 相似文献
294.
Dioxomolybdenum(VI) and dioxotungsten(VI) complexes: efficient catalytic activity for crosslinking reaction in ethylene‐vinyl acetate copolymer/alkoxysilane composites 下载免费PDF全文
Kenta Adachi Shoko Toyomura Yuko Miyakuni Suzuko Yamazaki Kensuke Honda Tomoyuki Hirano 《先进技术聚合物》2015,26(6):597-605
The catalytic performances of several bis(acetylacetonato)metal complexes [Cu(acac)2, Zn(acac)2, TiO(acac)2, VO(acac)2, MoO2(acac)2, and WO2(acac)2] were investigated for the crosslinking reaction via transesterifications in the ethylene‐vinyl acetate copolymer/tetraethoxysilane (EVA/TEOS) composite system by means of dynamic attenuated total reflectance Fourier transform infrared, solvent swelling, and solid‐state 29Si cross polarization/magic angle spinning nuclear magnetic resonance techniques. Results of the kinetic examination revealed that MoO2(acac)2 and WO2(acac)2 exhibited a higher catalytic activity than di‐n‐butyltin(IV) oxide, which is a catalyst most commonly used for the transesterification process in polymer system, but has a toxic effect on the environmental health. And furthermore, the crosslink density and final siloxane network structure of crosslinked EVA/TEOS composites are found to be greatly correlated with the catalyst used. On the basis of the SN2‐Si pathway, a plausible catalytic mechanism of MoO2(acac)2 and WO2(acac)2 was proposed for the crosslinking reaction via transesterifications of the vinyl acetate moieties in EVA backbone with the ethoxysilane groups in one TEOS molecule. The findings in this study may fill the blank in the high performance and environmentally friendly catalyst in the field of the crosslinking reactions in polymer system and provide useful clue for other transesterifications. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
295.
Polycyclic N‐Heterocyclic Compounds. Part 84: Reaction of N‐(pyrido[3′,2′:4,5]thieno[3,2‐d]pyrimidin‐4‐yl)amidines or N‐(pyrido[2′,3′:4,5]furo[3,2‐d]pyrimidin‐4‐yl)amidines with Hydroxylamine Hydrochloride 下载免费PDF全文
Kensuke Okuda Ryota Ide Naoto Uramaru Takashi Hirota 《Journal of heterocyclic chemistry》2015,52(3):880-887
The reactions of nine N‐(pyrido[3′,2′:4,5]thieno[3,2‐d]pyrimidin‐4‐yl)amidines ( 3 ) with hydroxylamine hydrochloride produced new cyclization products. These were formed via ring cleavage of the pyrimidine component followed by a 1,2,4‐oxadiazole‐forming ring closure to give N‐[2‐([1,2,4]oxadiazol‐5‐yl)thieno[2,3‐b]pyridin‐3‐yl]formamide oximes ( 11 ). Reaction of six N‐(pyrido[2′,3′:4,5]furo[3,2‐d]pyrimidin‐4‐yl)amidines ( 12 ) with hydroxylamine hydrochloride gave similar results. Effects of the newly synthesized compounds on pentosidine formation were also evaluated. 相似文献
296.
Takumi Higa Masato Fukui Kensuke Fukui Yoshiki Naganuma Yuji Kajita Tomohiko Inomata Tomohiro Ozawa Yasuhiro Funahashi Hideki Masuda 《Journal of inclusion phenomena and macrocyclic chemistry》2010,66(1-2):171-177
We synthesized a new amine-type host molecule 2 by 2 steps, using 1,3,5-tris(aminomethyl)-2,4,6-trimethylbenzene and 2,6-pyridinedicarboxaldehyde as starting materials. Recrystallization of 2·6H2O from hot acetonitrile, hot propionitrile and hexane/benzonitrile solutions gave colorless crystals of MeCN@2·MeCN·2H2O, EtCN@2·EtCN, and 8H2O@2·PhCN. In the former two crystals, the nitrile compounds were captured inside of the cavity of 2. On the other hand, in the latter one, the benzonitrile was laid outside 2. Infrared spectral measurements of MeCN@2·MeCN·2H2O, EtCN@2·EtCN, and 8H2O@2·PhCN showed that absorption bands assignable to the C ≡ N stretching vibrations of nitrile compounds were observed at 2240, 2241, and 2226 cm?1 for MeCN@2·MeCN·2H2O, EtCN@2·EtCN, and 8H2O@2·PhCN, respectively. The former two peaks shifted to a lower energy region by 6–13 and 21–26 cm?1 than those of liquid and gas phases of MeCN and EtCN, respectively. That for 8H2O@2·PhCN shifted to a slightly lower region by 2 and 12 cm?1 those of liquid and gas states of PhCN, respectively, indicating that the outer benzonitrile molecule dose not so much interact with 2 in the crystal. 相似文献
297.
Takahashi H Kageyama Y Kurihara K Takakura K Murata S Sugawara T 《Chemical communications (Cambridge, England)》2010,46(46):8791-8793
In water, phosphoric membrane molecule (V(-)) self-assembled to form an anionic giant vesicle, the surface of which served as a catalyst for the autocatalytic formation of V(-) from its membrane precursor (V*), and the amplified V(-) produced a new vesicle using the original vesicle as a scaffold. 相似文献
298.
Polycyclic N‐Heterocyclic Compounds. Part 78: Synthesis of N‐[2‐([1,2,4]Oxadiazol‐5‐yl)cyclohepten‐1‐yl]formamide Oximes and Their Evaluation as Inhibitors of Platelet Aggregation 下载免费PDF全文
Kensuke Okuda Ying‐Xue Zhang Takashi Hirota Kenji Sasaki 《Journal of heterocyclic chemistry》2014,51(2):518-522
N‐[2‐([1,2,4]Oxadiazol‐5‐yl)cyclohepten‐1‐yl]formamide oximes were synthesized by fusion of (6,7,8,9‐tetrahydro‐5H‐cyclohepta[1,2‐d]pyrimidin‐4‐yl)amidines with hydroxylamine hydrochloride through a subsequent rearrangement reaction. Effects of the products as well as the structurally related N‐[4‐([1,2,4]oxadiazol‐5‐yl)‐2,3‐dihydro[1]benzoxepin‐5‐yl]formamide oximes and N‐[4‐([1,2,4]oxadiazol‐5‐yl)‐2,3‐dihydro[1]benzothiepin‐5‐yl]formamide oximes on platelet aggregation were evaluated. 相似文献
299.
Polycyclic N‐Heterocyclic Compounds. Part 79: Synthesis of 2,4‐Disubstituted 6,7‐Dihydro‐5H‐benzo[6,7]cyclohepta[1,2‐d]pyrimidines as Potential Antiplatelet Aggregators 下载免费PDF全文
Libraries of tricyclic 2‐substituted 4‐alkylamino‐6,7‐dihydro‐5H‐benzo[6,7]cyclohepta[1,2‐d]pyrimidines were synthesized as part of our research to develop new effective antiplatelet drugs. Several alkyl and aryl groups were used as substituents at the 2‐position. Evaluation of the effects of the newly synthesized compounds on collagen‐induced platelet aggregation revealed several promising antiplatelet candidates with potencies superior to aspirin. 相似文献
300.
Yuko Ikeda Pranee Phinyocheep Sumet Kittipoom Jareerat Ruancharoen Yota Kokubo Yuichi Morita Kensuke Hijikata Shinzo Kohjiya 《先进技术聚合物》2008,19(11):1608-1615
Mechanical properties of partially hydrogenated natural rubber (HNR) vulcanizates were evaluated regarding their chemical structure and crystallizable nature of HNR, and are reported here, to the best of our knowledge, for the first time. HNRs of three levels of hydrogenation (20.6, 29.0, and 40.6 mol%) were successfully prepared by the chemical modification of natural rubber (NR) latex using N2H4 and H2O2 as reagents, in a sufficient amount for preparing sulfur‐crosslinked samples to be subjected to mechanical and structural measurements. The three HNR vulcanizates were found to be crystallizable upon stretching; it is noted that even 40.6 mol% hydrogenation did not prevent HNR vulcanizates from crystallization upon stretching, while their onset strain of crystallization was higher than that of NR vulcanizate. The hysteresis loss and residual strain up to a stretching ratio of 2 for the HNR vulcanizates tended to become larger with the increase in the degree of the hydrogenation. Tensile and dynamic mechanical properties of 20.6 mol% hydrogenated HNR vulcanizate were comparable to those of NR vulcanizate. From differential scanning calorimetry and temperature dispersion of dynamic modulus or loss, the glass transition temperatures of HNR vulcanizates were found to be almost the same as that of NR vulcanizate, which is also notable. The thermal stability of HNR vulcanizates was better than that of NR vulcanizate. Thus, this chemical modification seems to give a promising NR derivative whose properties can be equivalent or even better than the mother polymer. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献