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1.
The proposed structures of patellamides B and C, cytotoxic lipophilic cyclic peptides from a marine tunicate, have been revised on the basis of the spectral data of their partial hydrolysates, and their revised structures have been synthetically confirmed by the use of diphenyl phosphorazidate(DPPA) and diethyl phosphorocyanidate(DEPC). 相似文献
2.
Diethyl phosphorocyanidate (DEPC) can be efficiently used for the synthesis of α-amino nitriles from carbonyl compounds and amines. The reaction may be called a modified Strecker synthesis. 相似文献
3.
Takeo Kawashiro Fumihiro Yamasawa Yasumasa Okada Hirosuke Kobayashi Kunio Tanabe 《Mathematical Programming》1991,52(1-3):1-9
The uneven distribution of ventilation—perfusion ratios (
) in diseased lungs is the major cause of arterial hypoxemia. Farhi and Yokoyama (1967) and Yokoyama and Farhi (1967) were the first who used physiologically inert gases as indicator gases to assess the uneven distribution of
Wagner and his coworkers in San Diego (1977b) extended the method and elaborated the multiple inert gas elimination technique in which blood flows in 50 compartments with different
were estimated based on data for 6 indicator gases. They analyzed the indicator gas data through an enforced smoothing technique with the ridge regression. To get smooth distributions, they introduced a weighting function for
compartments and an additional treatment for the non-negativity of the blood flow. The weighting function was empirically obtained. We analyzed the data without putting any weights on
compartments nor any additional treatment for non-negativity of blood flow. The analytical method in the present study was a modified Newton method, which is one of the enforced smoothing method. Our method was capable of recovering all distribution patterns that were found through the method reported by Wagner et al. (1977b). 相似文献
4.
5.
Shinji Suzuki Furitsu Suzuki Yasumasa Kanie Koji Tsujitani Asako Hirai Hironori Kaji Fumitaka Horii 《Cellulose (London, England)》2012,19(3):713-727
The structure and crystallization of carefully isolated sub-elementary fibrils (SEFs) of bacterial cellulose have been investigated
using TEM, WAXD, and high-resolution solid-state 13C NMR. The addition of a suitable amount of fluorescent brightener (FB) to the incubation medium of Acetobacter xylinum effectively suppressed the aggregation of the SEFs into the microfibrils, as previously reported. However, this study confirmed
for the first time that serious structural change in the SEFs occurs during the removal of excess FB by washing with buffer
solutions having pH values higher than 6 or with the alkaline aqueous solution that was frequently used in previous studies.
In contrast, the isolation of unmodified SEFs was successfully performed by utilizing a washing protocol employing pH 7 citrate–phosphate
buffer solution containing 1% sodium dodecyl sulfate. High-resolution solid-state 13C NMR and WAXD measurements revealed that the SEFs thus isolated are in the noncrystalline state in which the pyranose rings
of the almost parallel cellulose chains appear to be stacked on each other. The respective CH2OH groups of the SEFs adopt the gt conformation instead of the tg conformation found in cellulose I
α
and I
β
crystals, and undergo significantly enhanced molecular motion in the absence of intermolecular hydrogen bonding associated
with these groups. The main chains are also subject to rapid motional fluctuations while maintaining the parallel orientation
of the respective chains, indicating that the SEFs have a liquid crystal-like structure with high molecular mobility. Moreover,
the SEFs crystallize into cellulose I
β
when the FB molecules that may adhere to the surface of the SEFs are removed by extraction with boiling 70 v/v% ethanol and
0.1N NaOH aqueous solution. On the basis of these results, the crystallization of the SEFs into the I
α
and I
β
forms is discussed, including the possible formation of the crystalline-noncrystalline periodic structure in native cellulose. 相似文献
6.
Sekimoto Shun Tatenuma Katsuyoshi Suzuki Yumi Tsuguchi Akira Tanaka Atsushi Tadokoro Takahiro Kani Yuko Morikawa Yasumasa Yamamoto Asaki Ohtsuki Tsutomu 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(2):1361-1366
The medical radionuclide 99Mo was produced by the 100Mo(γ,n) reaction using bremsstrahlung photons generated by an electron linear accelerator. The amount of 99Mo produced was compared to that predicted by calculation using the particles and heavy ion transport code system. From the 99Mo produced, highly pure 99mTc was separated using the so-called technetium master milker, and the chemical yield of 99mTc was 83–99 %. The installation of a new complex using this method and the electron linear accelerator with the preferable specification was suggested, and a possibility to supply the demand of 99mTc was discussed and shown.
相似文献7.
Yasumasa Nishiwaki Kazunari Masutani Yoshiharu Kimura Chan-Woo Lee 《Journal of polymer science. Part A, Polymer chemistry》2022,60(14):2043-2054
The ABCBA pentablock copolymers (p-d -l -PPS) comprising poly(d -lactide) (PDLA: A), poly(l -lactide) (PLLA: B) and poly(propylene succinate) (PPS: C) were successfully synthesized by two-step ring-opening polymerization (ROP) of d - and l -lactide using a dihydroxy-terminated PPS as a macro-initiator. The pentablock copolymers revealed the high stereocomplex (sc) crystallinity, thermal stability and elastomeric property in their solution-cast films. It was found that the Tg was found to be proportional to the PPS content, whereas the Tm was proportional to their average block length. The thermal resistivity of the copolymer films was found to be as high as 202°C owing to their sc formation. The copolymers also showed improved stereocomplexibility compared to the enantiomeric mixtures of triblock copolymers (PLLA-PPS-PLLA and PDLA-PPS-PDLA) having similar PLLA and PDLA chain lengths. These pentablock copolymers can afford thermoplastic elastomers or flexible plastic materials having a 100% bio-based content, showing high heat-resistive property. 相似文献
8.
9.
Yuta Suzuki Tetsuhiro NemotoShun-ichi Nakano Zengduo ZhaoYuta Yoshimatsu Yasumasa Hamada 《Tetrahedron letters》2014
A novel method for synthesizing 4,5-fused tricyclic quinoline derivatives based on an acid-promoted intramolecular Friedel–Crafts allenylation of anilines. Using aryl group-substituted propargyl alcohol derivatives with a meta-substituted N-Boc aniline unit as substrates, a four-step reaction sequence involving an acid-promoted intramolecular Friedel–Crafts allenylation of anilines, an acid-promoted intramolecular C–N bond formation, deprotection of the Boc group, and air oxidation proceeded in a single pot, producing the corresponding 4,5-fused tricyclic quinoline derivatives in 31–84% yield. 相似文献
10.
Fukushima Yasumasa Aikawa Shunichi 《Journal of inclusion phenomena and macrocyclic chemistry》2021,100(1-2):143-148
Journal of Inclusion Phenomena and Macrocyclic Chemistry - A colorimetric chemosensor is reported for Cu2+ by a simple mixture of two commercially available reagents, ponceau 6R (P6R) and... 相似文献