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51.
Sun-Chan Jeong Ichiro Katayama Hirokane Kawakami Yutaka Watanabe Hironobu Ishiyama Nobuaki Imai Yoshikazu Hirayama Hiroari Miyatake Masao Sataka Hiroyuki Sugai Satoru Okayasu Shin-Ichi Ichikawa Katsuhisa Nishio Shinichi Mitsuoka Takamitsu Nakanoya Takashi Hashimoto Takanori Hashimoto Masahito Yahagi 《Solid State Ionics》2009,180(6-8):626-630
The diffusion coefficients of Li in the NaTl-type Li intermetallic compound of β-LiGa have been measured by using a short-lived radioactive diffusion tracer. As the tracer, the α-emitting radioisotope of 8Li delivered as the energetic and pulsed beam from Tokai Radioactive Ion Accelerator Complex (TRIAC) was implanted into the β-LiGa compounds with the composition in the range of about 43 to 54 at.% Li. By analyzing the time-dependent yields of the α-particles measured according to the repetition cycle of the beam, the tracer diffusion coefficients were extracted over the wide range of Li composition. Abnormal composition-dependence of Li diffusion coefficients in β-LiGa was observed; the stoichiometric β-LiGa showed the highest diffusivity of Li. By referring to the composition-dependent diffusivity of Li in the iso-structural β-LiAl and β-LiIn, we could identify the abnormal diffusion of Li in very Li-poor composition of β-LiGa. The anomaly has been discussed qualitatively in terms of the formation of defect complex and the interaction between the constitutional defects. 相似文献
52.
Venkataprasad Jalli Suvratha Krishnamurthy Hiroyoshi Kawasaki Tetsuji Moriguchi Akihiko Tsuge 《合成通讯》2013,43(19):2216-2226
An efficient and facile method for the synthesis of novel spiro[indole-2,2′-pyrroles] from N-methyl-3-isatin imines, t-butyl isocyanide, and dialkyl acetylenedicarboxylate has been achieved by [3 + 2] cyclo addition reaction. All the products were purified by column chromatography as yellow solids and confirmed with 1H NMR, 13C NMR, fast atom bombardment, mass, and infrared. Compound 11 was further confirmed with x-ray analysis. 相似文献
53.
Wetting phenomena play important roles in several technological applications and in many physical and biological thin‐film phenomena, such as wetting, adhesion and friction. One of key issues of these studies is to control the surface energy (or wettability) dynamically for liquid transportation. We have developed a liquid crystal (LC) surface for use as a transport substrate since we expected that the surface energy of an LC surface can be controlled rapidly using an electric field. The rapid control of the polarisability (or wettability) of a liquid crystalline surface by an electric field has been demonstrated, together with the transportation of a liquid microdroplet. 相似文献
54.
Condensation reaction of 3,5-di-O-benzoyl-1,2-O-(1-cyanoben-zylidene)-β-D-arabinofuranose (2) with benzyl and allyl 2,3-di-O-benzoyl-5-O-triphenylmethyl-α-L-arabinofuranosides (5a and 5b) in methylene chloride in the presence of triphenylcarbenium tetrafluoroborate as catalyst under high vacuum gave α-(1→5)-linked dimeric D-arabinofuranoside derivatives (6a and 6b). One of the dimeric compounds (6a) was debenzoylated, triphenylmethylated, and rebenzoylated to give a dimeric homolog of 5a (8). Similarly for the preparation of 6a, 8 was condensed with 2 to provide an α-(1→5)-linked trimeric D-arabinofuranoside derivative (9). Further elongation of the glycoside chain might be possible in the same way. 相似文献
55.
Abstract Regioselective cleavage of 1,6-anhydro-maltose (1) with periodate and the subsequent recyclization with nitromethane gave 1,6-anhydro-3′-deoxy-3′-nitro-disaccharides (3). Three diastereomers, prepared by benzylidenation of 3, were separated by column chromatography. Each of 4′,6′-O-benzylidene derivatives successively underwent debenzylidenation, reduction of the nitro group, and peracetylation to give 3′-acetamido-3′-deoxy-disaccharide derivatives (7, 8, and 9). The configurations of the 3-amino sugar moietres in 7 (D-gluco), 8 (D-manno) and 9 (D-galacto) were determined on the basis of the 1H NMR data. The main product (7) was further modified to the 6-deoxy-6-nitro derivative. 相似文献
56.
Ken-Ichi Kanno Yuichi Kobayashi Shin-Ichiro Nishimura Hiroyoshi Kuzuhara Kenichi Hatanaka 《Journal of carbohydrate chemistry》2013,32(4-5):481-490
Abstract 1,6-Anhydro-2-deoxy-3,4-di-O-benzyl-2-phthalimido-β-d- glucopyranose (5) was synthesized from 1,6-anhydro-β-d-mannopyranose (1) in five steps. Compound 5 was polymerized under cationic conditions and selectively yielded glucosamine oligomers (degree of polymerization 5-7). Copolymerization of 5 with 1,6-anhydro-2,3,4-tri-O-benzyl-β-d-glucopyranose indicated the low reactivity of 5 with the active cation derived from 5. Deprotection of 2-deoxy-3,4-di-O-benzyl-2-phthalimido-(1→6)-β-d-glucopyranan (7) and N-acetylation gave 2-acetamido-2-deoxy-(1→6)-β-d-glucopyranan (9). 相似文献
57.
Dr. Kazukuni Tahara Yuki Yamamoto Dr. Dustin E. Gross Hiroyoshi Kozuma Yoko Arikuma Dr. Koji Ohta Dr. Yoshiko Koizumi Yuan Gao Dr. Yo Shimizu Prof. Shu Seki Dr. Kenji Kamada Prof. Jeffrey S. Moore Prof. Yoshito Tobe 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(34):11251-11260
We present herein the synthesis and properties of the largest hitherto unknown graphyne fragment, namely trigonally expanded tetrakis(dehydrobenzo[12]annulene)s (tetrakis‐DBAs). Intramolecular three‐fold alkyne metathesis reactions of hexakis(arylethynyl)DBAs 9 a and 9 b using Fürstner’s Mo catalyst furnished tetrakis‐DBAs 8 a and 8 b substituted with tert‐butyl or branched alkyl ester groups in moderate and fair yields, respectively, demonstrating that the metathesis reaction of this protocol is a powerful tool for the construction of graphyne fragment backbones. For comparison, hexakis(arylethynyl)DBAs 9 c – g have also been prepared. The one‐photon absorption spectrum of tetrakis‐DBA 8 a bearing tert‐butyl groups revealed a remarkable bathochromic shift of the absorption cut‐off (λcutoff) compared with those of previously reported graphyne fragments due to extended π‐conjugation. Moreover, in the two‐photon absorption spectrum, 8 a showed a large cross‐section for a pure hydrocarbon because of the planar para‐phenylene‐ethynylene conjugation pathways. Hexakis(arylethynyl)‐DBAs 9 c – e and 9 g and tetrakis‐DBA 8 b bearing electron‐withdrawing groups aggregated in chloroform solutions. Comparison between the free energies of 9 e and 8 b bearing the same substituents revealed the more favorable association of the latter due to stronger π–π interactions between the extended π‐cores. Polarized optical microscopy observations, DSC, and XRD measurements showed that 8 b and 9 e with branched alkyl ester groups displayed columnar rectangular mesophases. By the time‐resolved microwave conductivity method, the columnar rectangular phase of 8 b was shown to exhibit a moderate charge‐carrier mobility of 0.12 cm2 V?1 s?1. These results indicate that large graphyne fragments can serve as good organic semiconductors. 相似文献
58.
We previously reported that the peptide containing a Cys-Pro ester (CPE) moiety is spontaneously transformed into a peptide thioester via an N to S acyl shift followed by diketopiperazine formation. In an attempt to identify more reactive structures for the formation of a peptide thioester, we modified the CPE structure, in which the Pro residue in the CPE moiety was replaced with N-substituted glycine derivatives. These peptides were transformed into a peptide thioester more rapidly. Alternatively, the addition of an amino acid residue at the C-terminus of the CPE moiety also accelerated thioester formation. 相似文献
59.
Hajime Kawakami Makio C. Honda Shuichi Watanabe Toshiro Sino 《Journal of Radioanalytical and Nuclear Chemistry》2014,301(2):461-468
We carried out time-series observations of 210Po and 210Pb radioactivity in the western North Pacific Ocean. The sinking fluxes of particulate organic carbon (POC) in the mesopelagic zone were estimated from 210Po radioactivity during several seasons in the subarctic and subtropical regions of the western North Pacific. The seasonal changes of POC fluxes at a depth of 400 m were larger in the subarctic region than in the subtropical region. The annual mean POC flux at a depth of 400 m was larger in the subarctic region (57 mgC m?2 day?1) than in the subtropical region (36 mgC m?2 day?1). The annual mean of the e-ratio (the ratio of POC flux to primary productivity) in the subarctic region (18 %) was about twice the e-ratio in the subtropical region (10 %). These results imply that the efficiency of the biological pump is larger in the subarctic region than in the subtropical region of the western North Pacific. 相似文献
60.
I. Sugai M. Oyaizu Y. Takeda H. Kawakami K. Kawasaki T. Hattori T. Kadono 《Journal of Radioanalytical and Nuclear Chemistry》2014,299(2):1023-1028
Nitrided carbon stripper (NCS) foils with high nitrogen content were produced by ion beam sputtering of reactive nitrogen gas. Such foils seem to be very useful as strippers in high-intensity heavy ion accelerators. We have conducted comprehensive research, development, and production of such foils with high reproducibility. Krypton, a heavy noble gas, was mixed with the reaction nitrogen gas (IBSRN) in the ion beam sputtering process to produce stripper foils with short sputtering deposition time and long lifetimes in the high intensity ion beam irradiation. With the (N2 + Kr) mixed gas ions we investigated the influence of different sputtering angles (α) on the lifetime of the NCS-foils in case of poly-graphite material. The lifetime measurement of these foils of 20 ± 5 μg/cm2 was performed with a 3.2 MeV Ne+ ion beam as usual. The foils made at a sputtering angle of 15° showed a maximum of 11.0 and 7.5 C/cm2 average charge density, respectively, which corresponded to about 275 and 187 times the lifetime of the best commercially available foils. 相似文献