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41.
Takefumi Momose Kikuo Masuda Sachiko Furusawa Osamu Muraoka Toshiyuki Itooka 《合成通讯》2013,43(13):1039-1046
Isotwistanones have been highlighted since their use in the sesquiterpene syntheses.1 Begley and coworkers reported a new access to this system via the postulated aldol cyclization of bicyclo [4.3.1]decane-2, 7-dione.2 We have found another novel path of a similar mode. 相似文献
42.
Takefumi Kondo 《Mathematische Zeitschrift》2012,271(1-2):343-355
We construct a CAT(0) space Y with Izeki–Nayatani invariant δ(Y) =?1. By a similar construction, we also prove that there exists a CAT(0) space which does not have Markov type p for every p?>?1. 相似文献
43.
We demonstrate quasi-supercontinuum (quasi-SC) generation around the 1.3 μm wavelength region using ultrahigh-speed, wavelength-tunable, femtosecond soliton pulses based on an ultrashort-pulse laser system operating at a wavelength of 1.0 μm. The wavelength tuning range was from 1.0 to 1.9 μm, and the scanning speed was up to 1.3 MHz. A Gaussian-like quasi-SC with a bandwidth of 220 nm was generated at 1220 nm. The generated quasi-SC was used in an optical-coherence tomography system. High axial resolutions of 5.1 μm in air and 3.7 μm in tissue were obtained. A maximum sensitivity of 100 dB was achieved, and ultrahigh-resolution images of a hamster cheek pouch were observed. 相似文献
44.
Yongbing Shen Goulven Cosquer Hiroshi Ito David C. Izuogu Alex J. W. Thom Toshiaki Ina Tomoya Uruga Takefumi Yoshida Shinya Takaishi Brian K. Breedlove Zhao‐Yang Li Masahiro Yamashita 《Angewandte Chemie (International ed. in English)》2020,59(6):2399-2406
The first three‐dimensional (3D) conductive single‐ion magnet (SIM), (TTF)2[Co(pdms)2] (TTF=tetrathiafulvalene and H2pdms=1,2‐bis(methanesulfonamido)benzene), was electrochemically synthesised and investigated structurally, physically, and theoretically. The similar oxidation potentials of neutral TTF and the molecular precursor [HNEt3]2[M(pdms)2] (M=Co, Zn) allow for multiple charge transfers (CTs) between the SIM donor [M(pdms)2]n? and the TTF.+ acceptor, as well as an intradonor CT from the pdms ligand to Co ion upon electrocrystallisation. Usually TTF functions as a donor, whereas in our system TTF is both a donor and an accepter because of the similar oxidation potentials. Furthermore, the [M(pdms)2]n? donor and TTF.+ acceptor are not segregated but strongly interact with each other, contrary to reported layered donor–acceptor electrical conductors. The strong intermolecular and intramolecular interactions, combined with CT, allow for relatively high electrical conductivity even down to very low temperatures. Furthermore, SIM behaviour with slow magnetic relaxation and opening of hysteresis loops was observed. (TTF)2[Co(pdms)2] ( 2‐Co ) is an excellent building block for preparing new conductive SIMs. 相似文献
45.
Akira Hirao Reiko Inushima Takefumi Nakayama Takumi Watanabe Hee-Soo Yoo Takashi Ishizone Kenji Sugiyama Toyoji Kakuchi Stephane Carlotti Alain Deffieux 《European Polymer Journal》2011,47(4):713-722
A series of thermo-responsive and water-soluble 4- and 8-arm star-branched poly(2-(2′-methoxyethoxy)ethyl methacrylate) (poly(1)) with well-defined structures were synthesized by living anionic polymerization of 1, followed by a linking reaction with a core compound substituted with either four or eight benzyl bromide moieties. Furthermore, two kinds of sequentially different 4-arm star block copolymers composed of poly(1)-block-poly ((2,2-dimethyl-1,3-dioxolan-4-yl)methyl methacrylate) (poly(4)) were also synthesized by the same linking reaction of the corresponding AB or BA diblock copolymer anion with a core compound substituted with four benzyl bromide moieties. Thus, both well-defined 4-arm (AB)4 and (BA)4 star-block copolymers, whose A and B are poly(1) and poly(4) segments, were successfully synthesized. These star-block copolymers were quantitatively converted to the corresponding 4-arm (AC)4 and (CA)4 star-block copolymers with the same compositions by hydrolytic acetal cleavage of the poly(4) segment to poly(2,3-dihydroxypropyl methacrylate) (C segment). Poly(1) segments have LCST values and, on the other hand, both water-insoluble poly(4)s and water-soluble poly(2,3-dihydroxypropyl methacrylate)s are non-thermo-responsive segments. The thermo-responsive behavior of the resulting 4- and 8-arm star-branched poly(1) as well as the 4-arm (AB)4, (BA)4, (AC)4, and (CA)4 star-branched block copolymers has been extensively studied in terms of molecular weight, arm number, composition, and block sequence. As expected, such variables were observed to affect their LCST values. Interestingly, the thermo-responsive behavior of the 4-arm (AC)4 and (CA)4 stars was different from that of the block copolymers used as arm segments. 相似文献
46.
Let G be a group. Any G-module M has an algebraic structure called a G-family of Alexander quandles. Given a 2-cocycle of a cohomology associated with this G-family, topological invariants of (handlebody) knots in the 3-sphere are defined. We develop a simple algorithm to algebraically construct n-cocycles of this G-family from G-invariant group n-cocycles of the abelian group M. We present many examples of 2-cocycles of these G-families using facts from (modular) invariant theory. 相似文献
47.
Kayo Nakamura Kazuki Tsubokura Almira Kurbangalieva Yoichi Nakao Takefumi Murase Taiji Shimoda 《Journal of carbohydrate chemistry》2019,38(2):127-138
A convenient route to RIKEN click probes for glycoconjugation to the amino groups of lysines was established. N-Glycoclusters prepared with human serum albumin by the new method showed the same cell interaction profiles as those synthesized previously. The new route has thus significantly expanding the applicability to glycoconjugation and drug delivery systems. 相似文献
48.
Hiroyasu Izeki Takefumi Kondo Shin Nayatani 《Annals of Global Analysis and Geometry》2009,35(4):363-379
In this paper, using the generalized version of the theory of combinatorial harmonic maps, we give a criterion for a finitely
generated group Γ to have the fixed-point property for a certain class of Hadamard spaces, and prove a fixed-point theorem
for random-group actions on the same class of Hadamard spaces. We also study the existence of an equivariant energy-minimizing
map from a Γ-space to the limit space of a sequence of Hadamard spaces with the isometric actions of a finitely generated
group Γ. As an application, we present the existence of a constant which may be regarded as a Kazhdan constant for isometric
discrete-group actions on a family of Hadamard spaces.
相似文献
49.
50.
Anna L. Vagstad Takefumi Kuranaga Salome Püntener Vijaya R. Pattabiraman Jeffrey W. Bode Jrn Piel 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2268-2272
Post‐translational modifying enzymes from the S‐adenosyl‐l ‐methionine (AdoMet) radical superfamily garner attention due to their ability to accomplish challenging biochemical reactions. Among them, a family of AdoMet radical epimerases catalyze irreversible l ‐ to d ‐amino acid transformations of diverse residues, including 18 sites in the complex sponge‐derived polytheonamide toxins. Herein, the in vitro activity of the model epimerase OspD is reported and its catalytic mechanism and substrate flexibility is investigated. The wild‐type enzyme was capable of leader‐independent epimerization of not only the stand‐alone core peptide, but also truncated and cyclic core variants. Introduction of d ‐amino acids can drastically alter the stability, structure, and activity of peptides; thus, epimerases offer opportunities in peptide bioengineering. 相似文献