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131.
Nakanishi J Horiuchi Y Yamada T Ishii O Yamazaki M Yoshida M Fujimoto Y 《Optics letters》2011,36(10):1836-1838
We demonstrated a high-power and highly efficient Pr-doped waterproof fluoride glass fiber laser at 522.2 nm excited by two-polarization-combined GaN laser diodes and achieved a subwatt output power of 598 mW and slope efficiency of 43.0%. This system will enable us to make a vivid laser display, a photocoagulation laser for eye surgery, a color confocal scanning laser microscope, and an effective laser for material processing. Direct visible ultrashort pulse generation is also expected. 相似文献
132.
Supramolecular Phosphatases Formed by the Self‐Assembly of the Bis(Zn2+–Cyclen) Complex,Copper(II), and Barbital Derivatives in Water
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Dr. Mohd Zulkefeli Dr. Yosuke Hisamatsu Asami Suzuki Yuya Miyazawa Dr. Motoo Shiro Prof. Dr. Shin Aoki 《化学:亚洲杂志》2014,9(10):2831-2841
In our previous paper, we reported that a dimeric Zn2+ complex with a 2,2′‐bipyridyl linker (Zn2L1), cyanuric acid (CA), and a Cu2+ ion automatically assemble in aqueous solution to form 4:4:4 complex 3 , which selectively catalyzes the hydrolysis of mono(4‐nitrophenyl)phosphate (MNP) at neutral pH. Herein, we report that the use of barbital (Bar) instead of CA for the self‐assembly with Zn2L1 and Cu2+ induces 2:2:2 complexation of these components, and not the 4:4:4 complex, to form supramolecular complex 6 a , the structure and equilibrium characteristics of which were studied by analytical and physical measurements. The finding show that 6 a also accelerates the hydrolysis of MNP, similarly to 3 . Moreover, inspired by the crystal structure of 6 a , we prepared barbital units that contain functional groups on their side chains in an attempt to produce supramolecular phosphatases that possess functional groups near the Cu2(μ‐OH)2 catalytic core so as to mimic the catalytic center of alkaline phosphatase (AP). 相似文献
133.
Preparation of arsenic‐containing white rice grains as calibration standards for X‐ray fluorescence analysis of total arsenic in cereals
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Masaki Tatsumi Tetsuo Inui Kenta Hagiwara Atsushi Ohbuchi Yuya Koike Toshihiro Nakamura 《X射线光谱测定》2016,45(5):274-280
A preparation method of arsenic‐containing white rice grains as calibration standards was developed for the X‐ray fluorescence (XRF) analysis of arsenic in rice grains. Calibration standards were prepared by adding 10 g of white rice grains (from Japan) to 100 ml methanol‐containing dimethylarsinic acid corresponding to 2–100 µg arsenic. The mixture was heated, dried at 150 °C, cooled to room temperature, and then stored in a silica gel desiccator. A total of 5.0 g of each calibration standard was packed into a polyethylene cup (32 mm internal diameter and 23 mm height) covered with a 6‐µm‐thick polypropylene film and then analyzed by wavelength‐dispersive XRF spectrometry. The calibration curve for arsenic obtained from the white rice grains containing arsenic showed good linearity over a concentration range of 0.21–5.00 mg kg?1 arsenic. The limit of detection of arsenic was 0.080 mg kg?1. To check the reliability of the XRF method, the concentrations of arsenic in six samples of grain cereals and two samples of flour were compared with those obtained by atomic absorption spectrometry after acid decomposition. The values obtained by both analytical methods showed good agreement. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
134.
Matashige?Oyabu Kiyoshi?NomuraEmail author Yuya?Koike Atsushi?Okazawa 《Hyperfine Interactions》2016,237(1):68
Weathering steels (COR-TEN) were corroded by wet-dry cycles using a splay of various solutions in a laboratory. Corrosion products on weathering steel were characterized by X-ray diffractometry and Mössbauer spectrometry at room and low temperatures. Fine α-FeOOH, γ-FeOOH and γ-Fe 2 O 3 are fundamentally formed in various atmospheric conditions. β-FeOOH is additionally formed under the existence of chloride ions, but not formed when sulfate ions are coexisting. Spraying a NaF solution prevents the progress of corrosion. 相似文献
135.
We present a simple NMR method for microscopically exploring the local environment in carbon fibers. The method utilizes n-alkanes as probe molecules, where the n-alkanes penetrate carbon fibers of interest. The high-resolution (1)H NMR spectra for a mixture of a carbon fiber and n-alkanes acquired by this method show a shift of the resonance line, which is due to the local structure of the fiber. The utility of this method is discussed on the basis of the (1)H NMR spectra obtained. In addition, the (1)H distribution and the local motion in the structure of the carbon fiber are revealed in view of the (1)H NMR spectra. 相似文献
136.
Che DC Matsuo T Yano Y Bonnet L Kasai T 《Physical chemistry chemical physics : PCCP》2008,10(10):1419-1423
The reaction between HBr and OH leading to H(2)O and Br in its ground state is studied by means of a crossed molecular beam experiment for a collision energy varying from 0.05 to 0.26 eV, the initial OH being selected in the state |JOmega> = |3/2 3/2> by an electrostatic hexapole field. The reaction cross-section is found to decrease with increasing collision energy. This negative dependence suggests that there is no barrier on the potential energy surface for the formation pathway considered. The experimental results are compared with the previously reported quantum scattering calculations of Clary et al. (D. C. Clary, G. Nyman and R. Hernandez, J. Phys. Chem., 1994, 101, 3704), and briefly discussed in the light of skewed potential energy surfaces associated with heavy-light-heavy type reactions. 相似文献
137.
Dr. Masashi Hasegawa Dr. Yuki Nojima Prof. Dr. Yuya Nagata Prof. Dr. Kazuteru Usui Prof. Dr. Ken-ichi Sugiura Prof. Dr. Yasuhiro Mazaki 《European journal of organic chemistry》2023,26(36):e202300656
The synthesis, structure, and circularly polarized luminescence (CPL) of two types of shape-persistent [5]helicenes, hinged by a tethered (−OCH2CH2O−) or untethered (−OCH3) binaphthyl, are reported. The binaphthyl tethering system facilitated an effective Wittig ring-closure reaction in the synthesis of a macrocyclic precursor, which could be easily converted to the title compound via successive photocyclization. The tethered groups were replaced with untethered −OCH3 groups by treatment with BBr3 followed by methylation. Both compounds exhibited similar spectra, and their longest wavelength absorption band with a low intensity was attributed to the transition from HOMO to LUMO+1. These compounds exhibited CPL with higher dissymmetry factors glum values than unlocked helicenes. 相似文献
138.
Dr. Yuya Hu Dr. Rui Sang Dr. Robby Vroemans Guillaume Mollaert Dr. Rauf Razzaq Dr. Helfried Neumann Dr. Henrik Junge Prof. Dr. Robert Franke Dr. Ralf Jackstell Prof. Dr. Bert U. W. Maes Prof. Dr. Matthias Beller 《Angewandte Chemie (International ed. in English)》2023,62(6):e202214706
Diesters are of fundamental importance in the chemical industry and are used for many applications, e.g. as plasticizers, surfactants, emulsifiers, and lubricants. Herein, we present a straightforward and efficient method for the selective synthesis of diesters via palladium-catalyzed direct carbonylation of di- or polyols with readily available alkenes. Key-to-success is the use of a specific palladium catalyst with the “built-in-base” ligand L16 providing esterification of all alcohols and a high n/iso ratio. The synthesized diesters were evaluated as potential plasticizers in PVC films by measuring the glass transition temperature (Tg) via differential scanning calorimetry (DSC). 相似文献
139.
Enantioselective total synthesis of anhydrophytosphingosine pachastrissamine (jaspin B) was achieved using Sharpless asymmetric dihydroxylation and dirhodium(II)-catalyzed C-H amination as key steps. 相似文献
140.
Yuya Tanikawa Shingo Kanemura Dai Ito Yuxi Lin Motonori Matsusaki Kimiko Kuroki Hiroshi Yamaguchi Katsumi Maenaka Young-Ho Lee Kenji Inaba Masaki Okumura 《Molecules (Basel, Switzerland)》2021,26(10)
ERp57, a member of the protein disulfide isomerase family, is a ubiquitous disulfide catalyst that functions in the oxidative folding of various clients in the mammalian endoplasmic reticulum (ER). In concert with ER lectin-like chaperones calnexin and calreticulin (CNX/CRT), ERp57 functions in virtually all folding stages from co-translation to post-translation, and thus plays a critical role in maintaining protein homeostasis, with direct implication for pathology. Here, we present mechanisms by which Ca2+ regulates the formation of the ERp57-calnexin complex. Biochemical and isothermal titration calorimetry analyses revealed that ERp57 strongly interacts with CNX via a non-covalent bond in the absence of Ca2+. The ERp57-CNX complex not only promoted the oxidative folding of human leukocyte antigen heavy chains, but also inhibited client aggregation. These results suggest that this complex performs both enzymatic and chaperoning functions under abnormal physiological conditions, such as Ca2+ depletion, to effectively guide proper oxidative protein folding. The findings shed light on the molecular mechanisms underpinning crosstalk between the chaperone network and Ca2+. 相似文献