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21.
A new type of tomography system based on optical frequency-domain reflectometry is presented. Using an area sensor, the system can simultaneously measure three-dimensional reflectivity distributions in scattering media without the need for mechanical scanning. In preliminary experiments we demonstrate that a target (resolution chart) placed behind biological tissue can be imaged with high depth resolution (47 microm) for a short measurement time. 相似文献
22.
Makoto Minato Susumu Hiratsuka Takashi Ito 《Journal of organometallic chemistry》2004,689(6):1025-1028
The reaction of Cp2MoH2 (Cp=η5-C5H5) with homoallyl alcohol in the presence of a protonic acid afforded a cationic η3-crotyl molybdenum complex and a cyclic α-methyl-γ-hydroxypropyl molybdenum complex. This reaction proceeds via the stepwise formation of the cyclic complex, followed by formation of the η3-crotyl complex. 相似文献
23.
M Nakao Y Goto Y Matsuki A Hiratsuka T Watabe 《Chemical & pharmaceutical bulletin》1990,38(9):2561-2566
Regioselectivity in N-acetylation of nitro-0-phenylenediamine, a widely used hair dye component, by rat liver cytosolic N-acetyltransferases was studied in relation to its substituent effects on enzymatic N-acetylation of mono-substituted anilines. Nitro-p-phenylenediamine was acetylated specifically at the N4-position to afford the N4-monoacetate, a major urinary metabolite in the rat, when incubated with rat liver cytosol fortified with acetyl-coenzyme A. N1-Acetylation of nitro-p-phenylenediamine did not take place even when the N4-monoacetate was used as a substrate, suggesting a strong steric hindrance effect of the ortho nitro group on the enzymatic N1-acetylation. The steric hindrance effect of the nitro group on the cytosolic N-acetylation of the ortho amino group was revealed by a comparative study carried out by using aniline, three respective regioisomers of nitroanilines and phenylenediamines as model substrates. The comparative study also indicated the enzymatic N-acetylation of the mono-substituted anilines to be strongly influenced by the electronic effect of the substituents. Regioselective N-acetylation in the hepatic cytosol was also investigated with N1- and N4-monoacetates of 1,2,4-triaminobenzene. The monoacetates yielded the N1,N4-diacetate, another major urinary metabolite of the hair dye component, in the rat, without concomitant formation of the N2,N4-diacetate or the N1,N2,N4-triacetate. The triacetate was formed only from the N1,N2-diacetate in the enzymatic reactions. A comparative study, carried out by using N-mono-acetates of three regioisomeric phenylenediamines, indicated that the N-acetyl group had a potent steric hindrance effect on the primary amino group at the ortho position.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
24.
A. A. Kaminskii K. Ueda A. F. Konstantinova H. Yagi T. Yanagitani A. V. Butashin V. P. Orekhova J. Lu K. Takaichi T. Uematsu M. Musha A. Shirokava 《Crystallography Reports》2003,48(6):1041-1043
A continuous-wave lasing at 1 μm was excited by the radiation of semiconductor laser diodes at room temperature in nanocrystalline ceramics Y2O3 doped with Nd3+ and Yb3+ ions. The refractive indices of the undoped nanocrystalline Y2O3 ceramics were measured in the wavelength range 0.4–9 μm. 相似文献
25.
J.?LuEmail author H.?Yagi K.?Takaichi T.?Uematsu J.-F.?Bisson Y.?Feng A.?Shirakawa K.-I.?Ueda T.?Yanagitani A.A.?Kaminskii 《Applied physics. B, Lasers and optics》2004,79(1):25-28
A high-power, continuous-wave 0.6% Nd3+-doped ceramic Y3Al5O12 (Nd:YAG) laser has been developed. 110 W laser output at 1064 nm was obtained, with a slope efficiency of about 41%. The M2 factor was found to be around 6. The laser performance of the ceramic laser material was found to compare favorably with that obtained with single crystal Nd:YAG. PACS 42.55.-f; 42.55.Xi; 42.70.Hj 相似文献
26.
Biosynthesis of the Structurally Unique Polycyclopropanated Polyketide–Nucleoside Hybrid Jawsamycin (FR‐900848) 下载免费PDF全文
Dr. Tomoshige Hiratsuka Hideaki Suzuki Ryo Kariya Takashi Seo Dr. Atsushi Minami Prof. Dr. Hideaki Oikawa 《Angewandte Chemie (International ed. in English)》2014,53(21):5423-5426
The biosynthetic gene cluster of antifungal agent jawsamycin (FR‐900848) has been identified by heterologous expression. A series of gene inactivations and in vitro and in vivo analysis of key enzymes in the biosynthetic pathway established their functions. A novel mechanism involving a radical S‐adenosyl methionine (SAM) cyclopropanase collaborating with an iterative polyketide synthase is proposed for the construction of the unique polycyclopropanated backbone. Our reconstitution system sets the stage for studying the catalytic mechanism of this intriguing contiguous cyclopropanation. 相似文献
27.
Silylation Improves the Photodynamic Activity of Tetraphenylporphyrin Derivatives In Vitro and In Vivo 下载免费PDF全文
Prof. Hiroaki Horiuchi Prof. Masahiro Hosaka Hiroyuki Mashio Motoki Terata Prof. Shintaro Ishida Prof. Soichiro Kyushin Prof. Tetsuo Okutsu Prof. Toshiyuki Takeuchi Prof. Hiroshi Hiratsuka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(20):6054-6060
The effects of silyl and hydrophilic groups on the photodynamic properties of tetraphenylporphyrin (TPP) derivatives have been studied in vitro and in vivo. Silylation led to an improvement in the quantum yield of singlet oxygen sensitization for both sulfo and carboxy derivatives, although the silylation did not affect other photophysical properties. Silylation also improved the cellular uptake efficiency for both sulfo and carboxy derivatives, enhancing the in vitro photodynamic activity of the photosensitizer in U251 human glioma cells. The carboxy derivative (SiTPPC4) was found to show higher cellular uptake efficiency and in vitro photodynamic activity than the corresponding sulfo derivative (SiTPPS4), which indicates that the carboxy group is a more promising hydrophilic group than the sulfo group in the silylated porphyrin. SiTPPC4 was found to show high selective accumulation efficiency in tumors, although almost no tumor selectivity was observed for the nonsilylated porphyrin. The concentration of SiTPPC4 in tumors was 13 times higher than that in muscle 12 h after drug administration. We also studied tumor response after treatment and found that silylation enhanced in vivo photodynamic activity significantly. SiTPPC4 shows higher photodynamic activity than NPe6 with white light irradiation. 相似文献
28.
29.
The polarized absorption and ESR spectra of the acridine C-radical have been measured at room temperature, the radical was produced at 77 K by γ-ray irradiation of a stretched polyvinyl alcohol film saturated with acridine. The dichroism of the absorption spectrum has been well explained by the results of MO calculations for the acridine C-radical. 相似文献
30.
Core-forming hydrophobic alkyl groups were incorporated into amphiphilic PVLA to enhance the stability and inclusion ability of the homopolymeric micelles in water. The CAC and hepatocyte targeting in the synthesized P(VLA-co-VBH) were investigated in vitro. The CAC of the copolymers decreased and the stability of the copolymeric micelles increased with the incorporation of hydrophobic groups into the homopolymer. The galactose moieties in the copolymer could be recognized by the ASGP-R of the hepatocytes through a receptor-mediated mechanism. The copolymers efficiently delivered a water-insoluble drug to the hepatocytes. Hence, they be used to deliver hydrophobic drugs to cure various liver diseases. 相似文献