排序方式: 共有174条查询结果,搜索用时 15 毫秒
81.
K. Mawatari B. Oexl Y. Takaesu 《The European Physical Journal C - Particles and Fields》2011,71(11):1783
Light gravitino productions in association with a neutralino (selectron) in e
+
e
− (e
−
γ) collisions are restudied in a scenario that the lightest supersymmetric particle is a gravitino and the produced neutralino
(selectron) promptly decays into a photon (electron) and a gravitino. We explicitly give the helicity amplitudes for the production
processes by using the effective goldstino interaction Lagrangian, and present the cross sections with different collision
energies and mass spectra. We also examine selection efficiencies by kinematical cuts and beam polarizations for the signal
and background processes, and show that the energy and angular distributions of the photon (electron) can explore the mass
of the t-channel exchange particle as well as the mass of the decaying particle at a future e
+
e
− (e
−
γ) collider. 相似文献
82.
Rattanaporn Wansri Aye Chan Khine Lin Jutharat Pengon Sumalee Kamchonwongpaisan Nitipol Srimongkolpithak Roonglawan Rattanajak Patcharin Wilasluck Peerapon Deetanya Kittikhun Wangkanont Kowit Hengphasatporn Yasuteru Shigeta Jatupol Liangsakul Aphinya Suroengrit Siwaporn Boonyasuppayakorn Taksina Chuanasa Wanchai De-eknamkul Supot Hannongbua Thanyada Rungrotmongkol Supakarn Chamni 《Molecules (Basel, Switzerland)》2022,27(9)
Piper nigrum, or black pepper, produces piperine, an alkaloid that has diverse pharmacological activities. In this study, N-aryl amide piperine analogs were prepared by semi-synthesis involving the saponification of piperine (1) to yield piperic acid (2) followed by esterification to obtain compounds 3, 4, and 5. The compounds were examined for their antitrypanosomal, antimalarial, and anti-SARS-CoV-2 main protease activities. The new 2,5-dimethoxy-substituted phenyl piperamide 5 exhibited the most robust biological activities with no cytotoxicity against mammalian cell lines, Vero and Vero E6, as compared to the other compounds in this series. Its half-maximal inhibitory concentration (IC50) for antitrypanosomal activity against Trypanosoma brucei rhodesiense was 15.46 ± 3.09 μM, and its antimalarial activity against the 3D7 strain of Plasmodium falciparum was 24.55 ± 1.91 μM, which were fourfold and fivefold more potent, respectively, than the activities of piperine. Interestingly, compound 5 inhibited the activity of 3C-like main protease (3CLPro) toward anti-SARS-CoV-2 activity at the IC50 of 106.9 ± 1.2 μM, which was threefold more potent than the activity of rutin. Docking and molecular dynamic simulation indicated that the potential binding of 5 in the 3CLpro active site had the improved binding interaction and stability. Therefore, new aryl amide analogs of piperine 5 should be investigated further as a promising anti-infective agent against human African trypanosomiasis, malaria, and COVID-19. 相似文献
83.
Dr. Koji Numasawa Prof. Kenjiro Hanaoka Naoko Saito Prof. Yoshifumi Yamaguchi Takayuki Ikeno Honami Echizen Dr. Masahiro Yasunaga Dr. Toru Komatsu Dr. Tasuku Ueno Prof. Masayuki Miura Prof. Tetsuo Nagano Prof. Yasuteru Urano 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(15):6071-6076
Folate receptors (FRs) are membrane proteins involved in folic acid uptake, and the alpha isoform (FR-α) is overexpressed in ovarian and endometrial cancer cells. For fluorescence imaging of FRs in vivo, the near-infrared (NIR) region (650–900 nm), in which tissue penetration is high and autofluorescence is low, is optimal, but existing NIR fluorescent probes targeting FR-α show high non-specific tissue adsorption, and require prolonged washout to visualize tumors. We have designed and synthesized a new NIR fluorescent probe, FolateSiR-1 , utilizing a Si-rhodamine fluorophore having a carboxy group at the benzene moiety, coupled to a folate ligand moiety through a negatively charged tripeptide linker. This probe exhibits very low background fluorescence and afforded a tumor-to-background ratio (TBR) of up to 83 in FR-expressing tumor-bearing mice within 30 min. Thus, FolateSiR-1 has the potential to contribute to the research in the field of biology and the clinical medicine. 相似文献
84.
Tsukahara T Mawatari K Hibara A Kitamori T 《Analytical and bioanalytical chemistry》2008,391(8):2745-2752
A novel air-pressure-based nanofluidic control system was developed and its performance was examined. We found that the flow
in a 100 nm scale nanochannel on a chip (called an extended nanospace channel) could be controlled within the pressure range
of 0.003–0.4 MPa, flow rate range of 0.16–21.2 pL/min, and residence time range of 24 ms–32.4 s by using the developed nanofluidic
control system. Furthermore, we successfully demonstrated an enzyme reaction in which the fluorogenic substrate TokyoGreen-β-galactoside (TG-β-gal) was hydrolyzed to the fluorescein derivative TokyoGreen (TG) and β-galactose by the action of β-galactosidase enzyme as a calalyst in a Y-shaped extended nanospace channel. The parameters for the reaction kinetics, such
as K
m, V
max and k
cat, were estimated for the nanofluidic reaction, and these values were compared with the results of bulk and microfluidic reactions.
A comparison showed that the enzyme reaction rate in the Y-shaped extended nanospace channel increased by a factor of about
two compared with the rates in the bulk and micro spaces. We thought that this nanospatial property resulted from the activated
protons of water molecules in the extended nanospace. This assumption was supported by the result that the pH dependence of
the maximum enzyme activity in the Y-shaped extended nanospace channel was slightly different from that in the bulk and micro
spaces.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
85.
Koji Numasawa Kenjiro Hanaoka Naoko Saito Yoshifumi Yamaguchi Takayuki Ikeno Honami Echizen Masahiro Yasunaga Toru Komatsu Tasuku Ueno Masayuki Miura Tetsuo Nagano Yasuteru Urano 《Angewandte Chemie (International ed. in English)》2020,59(15):6015-6020
Folate receptors (FRs) are membrane proteins involved in folic acid uptake, and the alpha isoform (FR‐α) is overexpressed in ovarian and endometrial cancer cells. For fluorescence imaging of FRs in vivo, the near‐infrared (NIR) region (650–900 nm), in which tissue penetration is high and autofluorescence is low, is optimal, but existing NIR fluorescent probes targeting FR‐α show high non‐specific tissue adsorption, and require prolonged washout to visualize tumors. We have designed and synthesized a new NIR fluorescent probe, FolateSiR‐1 , utilizing a Si‐rhodamine fluorophore having a carboxy group at the benzene moiety, coupled to a folate ligand moiety through a negatively charged tripeptide linker. This probe exhibits very low background fluorescence and afforded a tumor‐to‐background ratio (TBR) of up to 83 in FR‐expressing tumor‐bearing mice within 30 min. Thus, FolateSiR‐1 has the potential to contribute to the research in the field of biology and the clinical medicine. 相似文献
86.
Shigeta Y 《The Journal of chemical physics》2008,128(16):161103
We have derived a quantum distribution function in terms of cumulants that are expectation values of a (anti)symmetric-ordered product of position and momentum fluctuation operators. A second-order approximation leads a Gaussian distribution function, which is positive definite and has proper marginals so that the Shannon entropy can be evaluated. 相似文献
87.
Yoshikuni Kikutani Kazuma Mawatari Akihide Hibara Takehiko Kitamori 《Mikrochimica acta》2009,164(3-4):241-247
A new method has been developed for liquid–liquid microextraction utilizing a circulation microchannel. A glass microchemical chip having a circular shallow microchannel in contact with a surrounding deeper microchannel was fabricated by a two-step photolithographic wet-etching technique. Surface modification reagent was selectively introduced to the shallow channel by utilizing capillary force, and the surface of the shallow channel was selectively made hydrophobic. With the aid of the hydrophobic/hydrophilic surface patterning, it was possible to keep organic solvent in the circular channel while the aqueous sample solution was continuously flowing in the deep channel. As a result, concentration extraction from sample solution to stationary extractant with a nanoliter scale volume became possible. Concentration extraction has been difficult in a multiphase continuous flow. Function of the newly developed microextraction system was verified with methyl red as a test sample, and concentration extraction to reach equilibrium was successfully carried out. A novel surface modification method utilizing frozen liquid as a masking material was also developed as a reverse process to make the shallow channel hydrophilic and the deep channel hydrophobic. Visualization of circulation motion inside the circular shallow channel induced by flow in the deep channel was observed with a particle tracing method. 相似文献
88.
Design and synthesis of an enzyme activity-based labeling molecule with fluorescence spectral change
Komatsu T Kikuchi K Takakusa H Hanaoka K Ueno T Kamiya M Urano Y Nagano T 《Journal of the American Chemical Society》2006,128(50):15946-15947
Methods of covalent labeling of a specific tag protein with small-molecular dyes play an important role in studying dynamic behaviors of proteins in living cells. On the basis of quinone methide chemistry, we designed and synthesized a beta-galactosidase labeling probe, CMFbeta-gal, which shows a fluorescence wavelength change accompanying the labeling reaction, owing to fluorescence resonance energy transfer (FRET). Since the FRET efficiency changes accompanying the labeling reaction, fluorescence of labeled protein can be observed separately from that of the unreacted probe, so immediate detection of the target protein is possible. This is the first report of a protein labeling probe which features a change of fluorescence wavelength upon reaction, allowing the labeled protein to be detected even in the presence of unreacted probe. 相似文献
89.
A high-performance liquid chromatographic method involving post-column photochemical reaction and fluorimetric detection has been developed for the determination of kynurenine in serum. Kynurenine was separated on a column of Capcell Pak C18 (resistant to pH 10). The mobile phase consisted of 0.05 M Na2B4O7-0.1 M KH2PO4 buffer (pH 8.5)-ethanol (97:3, v/v) containing 60 mM hydrogen peroxide. The post-column reagent, containing 60% (v/v) ethanol, was mixed with the mobile phase, which was irradiated with ultraviolet light to induce fluorescence. The recovery of kynurenine was 95.9 +/- 5.0% (n = 6). The method allows the determination of as little as 2 pmol of kynurenine. 相似文献
90.
Yoshifumi Sasano Hiroki Tanaka Yohei Haketa Yoichi Kobayashi Yukihide Ishibashi Tatsuki Morimoto Ryuma Sato Yasuteru Shigeta Nobuhiro Yasuda Tsuyoshi Asahi Hiromitsu Maeda 《Chemical science》2021,12(28):9645
In this study, charged π-electronic species are observed to develop stacking structures based on electrostatic and dispersion forces. iπ–iπ Interaction, defined herein, functions for the stacking structures consisting of charged π-electronic species and is in contrast to conventional π–π interaction, which mainly exhibits dispersion force, for electronically neutral π-electronic species. Establishing the concept of iπ–iπ interaction requires the evaluation of interionic interactions for π-electronic ion pairs. Free base (metal-free) and diamagnetic metal complexes of 5-hydroxy-10,15,20-tris(pentafluorophenyl)porphyrin were synthesized, producing π-electronic anions upon the deprotonation of the hydroxy unit. Coexisting cations in the ion pairs with porphyrin anions were introduced as the counter species of the hydroxy anion as a base for commercially available cations and as ion-exchanged species, via Na+ in the intermediate ion pairs, for synthesized π-electronic cations. Solid-state ion-pairing assemblies were constructed for the porphyrin anions in combination with aliphatic tetrabutylammonium (TBA+) and π-electronic 4,8,12-tripropyl-4,8,12-triazatriangulenium (TATA+) cations. The ordered arrangements of charged species, with the contributions of the charge-by-charge and charge-segregated modes, were observed according to the constituent charged building units. The energy decomposition analysis (EDA) of single-crystal packing structures revealed that electrostatic and dispersion forces are important factors in stabilizing the stacking of π-electronic ions. Furthermore, crystal-state absorption spectra of the ion pairs were correlated with the assembling modes. Transient absorption spectroscopy of the single crystals revealed the occurrence of photoinduced electron transfer from the π-electronic anion in the charge-segregated mode.π-Electronic ion pairs comprising porphyrin-based π-electronic anions have exhibited characteristic assembling modes and resulting electronic properties such as solid-state absorption and photoinduced electron transfer. 相似文献