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891.
892.
Koji Kano Hideki Hasegawa 《Journal of inclusion phenomena and macrocyclic chemistry》2001,41(1-4):41-47
Anionic N-acetylated -aminoacids (AcTrp-, AcPhe-, AcLeu- and AcVal-) are bound to protonatedheptakis(6-amino-6-deoxy)--cyclodextrin(per-NH3
+--CD) by a cooperative work of inclusion and Coulomb interactions.Such complexation occurs enantioselectively ((S)-selective)and is accompanied bypositive entropy changes. Similar (S)-selectivecomplexation occurs in the oppositelycharged system. Namely, cationic -aminoacid methyl esters are enantioselectivelybound to dissociatedheptakis(6-carboxymethylthio-6-deoxy)--cyclodextrin(per-COO---CD). In order to obtain thegeneral mechanism for complexationof a charged host with an oppositely charged guest,we examined the 1H NMR spectra oncomplexation of simple carboxylate anions suchas p-methylbenzoate anion andalkanoate anions with per-NH3
+--CD.Both Coulomb interactions andinclusion are essential to form stable complexesof these carboxylate anions. In allcases, positive entropy changes promote thecomplexation between the carboxylateanions and per-NH3
+--CD. Dehydrationfrom both charged host and guestis the origin of entropic gains. The mechanism forcomplexation of a charged host withan oppositely charged guest involving the cooperativework of inclusion and Coulombinteractions and positive entropy change due todehydration upon complexation isgenerally applied for related systems such asenantioselective complexation ofRu(phen)3
2+ with per-COO---CDand of Ru(phen)3
2+with DNA. 相似文献
893.
Hideki Tachi Takayuki Yamamoto Masamitsu Shirai Masahiro Tsunooka 《Journal of polymer science. Part A, Polymer chemistry》2001,39(9):1329-1341
The photochemical behavior of quaternary ammonium salts (QA salts) with N,N‐dimethyldithiocarbamate as photobase generators and the photoinitiated thermal crosslinking of poly(glycidyl methacrylate) (PGMA) with the QA salts were investigated. The formation of basic compounds in the photolysis of 1‐phenacyl‐(1‐azonia‐4‐azabicyclo[2,2,2]octane) N,N‐dimethyldithiocarbamate was ascertained by the color change of phenol red as an acid–base indicator. 1H NMR spectra of photoproducts in CDCl3 under N2 showed that the photolysis of 1‐naphthoylmethyl‐(1‐azonia‐4‐azabicyclo[2,2,2]octane) N,N‐dimethyldithiocarbamate resulted in the quantitative formation of triethylenediamine and a dithiocarbamate derivative. The presence of oxygen in the photolysis decreased the photolysis rate. The amine was also detected in its photolysis in polystyrene films. The effects of ammonio groups and counteranions of QA salts on the photoinitiated thermal crosslinking of PGMA films were also investigated. Quaternary ammonium dithiocarbamates acted as excellent photobase generators and effective photoinitiated thermal crosslinkers for PGMA. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1329–1341, 2001 相似文献
894.
Wahyu Widada Hideki Kinjo Hiroaki Kuze Nobuo Takeuchi Makoto Sasaki 《Optical Review》2001,8(5):382-387
This paper describes the lidar inversion of the tropospheric aerosol extinction profiles under the influence of multiple-scattering effects for various elevation angles of lidar detection. A single-scattering lidar equation is employed to analyze lidar signals with multiple-scattering contributions that are calculated by the Monte Carlo method for given atmospheric conditions. We calculate errors in the optical thickness from the results with and without multiple-scattering effects. It is found that the errors vary in a range of 2#x2013;18#x0025; according to the optical thickness variation of 0.19#x2013;3.8. The dependence of the error on the field-of-view angle of the lidar observation is also discussed. 相似文献
895.
Ho Sik Kim Sam Tag Kwag Kyung Ok Choi Yoshihisa Okamoto Shinnosuke Kajiwara Noriko Fujiwara Yoshihisa Kurasawa 《Journal of heterocyclic chemistry》2000,37(1):103-107
The reaction of 6‐chloro‐2‐hydrazinoquinoxaline 4‐oxide 1b with acetylacetone or benzoylacetone gave 6‐chloro‐2‐(3,5‐dimethylpyrazol‐i‐yl)quinoxaline 4‐oxide 5a or 6‐chloro‐2‐(3‐methyl‐5‐phenylpyrazol‐1‐yl)quinoxaline 4‐oxide 5b , respXectively. Compound 5a or 5b was converted into the pyrrolo[1,5‐a]quinoxaline 6a or 6b , triazolo[4,3‐a]quinoxaline 9a or 9b , and tetrazolo[1,5‐a]quinoxaline 10. 相似文献
896.
Koji Fujiwara 《Proceedings of the American Mathematical Society》2000,128(12):3463-3464
Farb and Masur showed that an irreducible lattice in a semisimple Lie group of rank at least two always has finite image by a homomorphism into the outer automorphism group of a closed, orientable surface group. We point out that their theorem extends to the outer automorphism groups of a certain class of torsion-free, freely indecomposable word-hyperbolic groups.
897.
Masafumi Jinno Hisayoshi Kurokawa Masaharu Aono Hideki Ninomiya 《Czechoslovak Journal of Physics》2000,50(3):433-439
The similarity of the abundance of heavy nuclei in the Universe with that of the nuclei produced in the fully reproducible reactions of protons in host metals like palladium, nickel or others is evident and can be described by the same exponential function of the distribution probability N(Z) depending on the proton number Z of the nuclides. This agrees with the earlier derived consequence of a 3
n
relation for magic numbers and an alternative foundation of the nuclear shell model. Compared to femtometer-attosecond reactions in the big bang, the low energy nuclear reactions in the host metals have picometer distances and megasecond duration. For this picometer distance, a combination of the swimming electron layer and Debye screening model with a metal-plasma dielectric model is presented. 相似文献
898.
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