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41.
It was found that a commercial silicon photodiode modified only by removing its window can be used as a low-background detector of -rays from45Ca solutions. We built a test system which could count -rays from 0.21% hot CaCl2 solutions in the concentration range of 10–5–10–8M with linear sensitivity. Such a system using a small photodiode for real-time detection of -rays from small amounts of assay solutions could have many applications in the field of biophysics, biochemistry and physiology, e.g., in the study of Ca-binding proteins. This photodiode was also found to be suitable for measurement of low-energy -rays from14C. 相似文献
42.
It is shown that the standard model of the electroweak interactions holds at an infinite sublayer quark level, insofar as we consider the weak isospin doublet (u
L,u
L
cp
, whereu
is an infinite number of quarks at an infinite sublayer level. 相似文献
43.
Sato K Akai S Sugita N Ohsawa T Kogure T Shoji H Yoshimura J 《The Journal of organic chemistry》2005,70(19):7496-7504
[reactions: see text] The novel and stereocontrolled synthesis of (+/-)-tetrodotoxin from myo-inositol is described. The key steps involve the stepwise oxidation of hydroxyl groups to the carbonyl function, followed by the addition of specific nucleophiles, including the successive spiro alpha-chloroepoxide formation and its ring-opening with the azide anion, to give the desired branched chain structures (5-->6, 17-->18-->19-->20 and 23-->24-->25) with the desired regio- and stereoselectivities in high yields. The stepwise conversion of the alpha-azido aldehyde 25 to the delta-lactone 29, followed by reduction of the azide, introduction of a guanidine moiety, aldehyde formation, and deprotection, produced the (+/-)-tetrodotoxin. 相似文献
44.
Yokoyama K Teranishi Y Toya Y Shirai T Fukuda Y Aoyama M Akahane Y Inoue N Ueda H Yamakawa K Yokoyama A Yamada H Yabushita A Sugita A 《The Journal of chemical physics》2004,120(20):9446-9449
Optimal laser control for ultrafast selection of closely lying excited states whose energy separation is smaller than the laser bandwidth is reported on the two-photon transition of atomic cesium; Cs(6S-->7D(J), J=5/2 and 3/2). Selective excitation was carried out by pulse shaping of ultrashort laser pulses which were adaptively modulated in a closed-loop learning system handling eight parameters representing the electric field. Two-color fluorescence from the respective excited states was monitored to measure the selectivity. The fitness used in the learning algorithm was evaluated from the ratio of the fluorescence yields. After fifty generations, a pair of nearly transform-limited pulses were obtained as an optimal pulse shape, proving the effectiveness of the "Ramsey fringes" mechanism. The contrast of the selection ratio was improved by approximately 30% from the simple "Ramsey fringes" experiment. 相似文献
45.
A new P-chiral phosphine ligand, (R,R)-2,3-bis(tert-butylmethylphosphino)quinoxaline, has been prepared by the reaction of enantiomerically pure tert-butylmethylphosphine-borane with 2,3-dichloroquinoxaline. This ligand, in contrast to most of the previously reported P-chiral ligands, is an air-stable solid and exhibits excellent enantioselectivities in both Rh-catalyzed asymmetric hydrogenations and Rh- or Pd-catalyzed carbon-carbon bond-forming reactions. 相似文献
46.
47.
Akio Kobori Taichiro Arai Yuya Sakata Takayuki Sugita Asako Yamayoshi Akira Murakami 《Tetrahedron letters》2018,59(41):3690-3693
Molecular switches controlled by light stimuli can be applicable to the variety of the biological application. In this study, skeletal structures of a chromophore of fluorescent protein were applied as aglycones of newly designed photochromic nucleosides, “Fluorescent protein-inspired nuceloside: FIN”. Phosphoramidite units of the photochromic nucleosides having imidazolinone derivatives with benzylidene or 3-pyridilidene groups were successfully synthesized for FIN-containing ODNs. Thermodynamic studies of the FIN-containing ODNs revealed that photo-irradiation with specific wavelength induced stability change of the duplexes. 相似文献
48.
Ryohei Sugita Natsuko I. Kobayashi Atsushi Hirose Yoshimi Ohmae Keitaro Tanoi Tomoko M. Nakanishi 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(2):1411-1416
We have developed a real-time radioisotope imaging system (RRIS) that can nondestructively trace 14C-labeled chemicals in plants. In an experiment, after feeding 14CO2 to a plant, the plant was fixed inside a box where lighting was regulated, and beta rays emitted from the 14C in the plant were intermittently imaged using the developed system. As a first step, using a series of standard sources of 14C, the data depth and detection limits of the 14C images captured by the RRIS were evaluated for various integral times. As a result, the linearity between the 14C activity and signal intensity was determined for the range 103. Next, the linearity was validated using plant (Arabidopsis thaliana) organs, resulting that the linearity was shown in the case of young leaf, but was not maintained in the thick organs, such as a flower, mature leaf, siliques, and stem. Considering the good correlation between the intensity by RRIS and the PSL value by an imaging plate (IP) as well as the relative low energy of beta rays emitted from 14C, the thickness of the organs would easily affect the quantitativity of the RRIS as well as an IP. Our findings prove that sequential images of 14C in a living plant sample in a regulated light and air environment can be nondestructively analyzed using the developed system, whose quantitativity is similar to that of an IP. 相似文献
49.
Nurul Sheeda Satoshi OkamiTakashi Komine Ryuji Sugita 《Journal of magnetism and magnetic materials》2008
Edge printing is one of the perpendicular magnetic printing methods for writing servo signals with high speed, high accuracy and low cost. Sub-peaks of waveform from edge printed media are concerned as the sub-peaks can cause errors during the read-back process. In this study, in order to reduce sub-peaks, the influence of printing field, bit length and patterned magnetic layer thickness of master medium on sub-peaks is investigated by using a metal-evaporated (ME) tape as a slave medium. The results show that sub-peak to main peak ratio decreases with stronger printing field, smaller bit length and thicker patterned magnetic layer of master media. 相似文献
50.
Yoshikazu Horino Miki Sugata Tetsu Sugita Ataru Aimono Hitoshi Abe 《Tetrahedron letters》2017,58(22):2131-2134
A palladium-catalyzed reaction of easily accessible 3-(pinacolatoboryl)allyl acetates and aldehydes provides facile access to synthetically useful homoaldol equivalent products with high diastereoselectivity. The reaction presumably proceeds via allylation of aldehydes with α-acetoxy allylboronates that produced in situ by reductive elimination from allylic gem-palladium/boryl intermediates. 相似文献