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71.
Guangrui Chen Yuxing Yan Dr. Jie Wang Prof. Yong Sik Ok Guiyuan Zhong Prof. Bu Yuan Guan Prof. Yusuke Yamauchi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(44):19831-19836
Mesoporous core–shell nanostructures with controllable ultra-large open channels in their nanoshells are of great interest. However, soft template-directed cooperative assembly to mesoporous nanoshells with highly accessible pores larger than 30 nm, or even above 50 nm into macroporous range, remains a significant challenge. Herein we report a general approach for precisely tailored coating of hierarchically macro-/mesoporous polymer and carbon shells, possessing highly accessible radial channels with extremely wide pore size distribution from ca. 10 nm to ca. 200 nm, on diverse functional materials. This strategy creates opportunities to tailor the interfacial assembly of irregular mesostructured nanounits on core materials and generate various core–shell nanomaterials with controllable pore architectures. The obtained Fe,N-doped macro-/mesoporous carbon nanoshells show enhanced electrochemical performance for the oxygen reduction reaction in alkaline condition. 相似文献
72.
73.
Prof. Akiharu Satake Yuki Suzuki Motonobu Sugimoto Dr. Yusuke Kuramochi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(3):669-684
Bis(imidazolylporphyrinatozinc) molecules linked through a 1,3-butadiynylene moiety respond to the solvents they are dissolved in to afford exclusively extended (E) or stacked (S) supramolecular polymers. This system is expected to be a solvation/desolvation indicator. However, the principles underlying the solvent-dependent formation of the two types of polymers and the mechanism of the transformation between them are unclear. The formation of the polymers is considered to depend on the two types of complementary coordination bonds that can be formed and the π–π interactions between the porphyrins. In this study, the contributions and solvent dependence of both the coordination bonds and the π–π interactions have been investigated. The results clearly indicate that the coordination bonds are weakly or little solvent-dependent, and that the π–π interactions function effectively only in the inner porphyrins of the S-polymer and are strongly solvent-dependent. Thermodynamic analysis revealed that the formation of the E- or S-polymer in solution is determined by the total energies and the type of solvent used. The transformation of the E- to S-polymer was investigated by gel permeation chromatography. The kinetics of the transformation were also determined. The role of the terminal imidazolylporphyrinatozinc moieties was also investigated: The results indicate that the transformation from the E- to S-polymer occurs by an exchange mechanism between the polymers, induced by attack of terminal free imidazolyl groups on a polymer to zinc porphyrins on other polymers. 相似文献
74.
Yusuke Tanaka Tomotaka Murayama Dr. Atsuya Muranaka Dr. Eiyu Imai Prof. Dr. Masanobu Uchiyama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(8):1768-1771
We designed and synthesized a new type of small helical molecule exhibiting intense circularly polarized luminescence (CPL) ( 12H ) by modifying a 20π-electron hemiporphyrazine with a large transition magnetic dipole moment. The hemiporphyrazine ring was opened and one additional pyridine unit was introduced, resulting in an overlap of two pyridine rings. X-ray structure analysis confirmed that 12H and its zinc complex ( 1Zn ) adopt a helical geometry. A racemic mixture of 1Zn was resolved into two enantiomers ((P)- and (M)- 1Zn ), which exhibited CPL with a high luminescence dissymmetry factor (glum) value of ±2.1×10−2. The origin of the large glum value was rationalized by means of DFT calculations. Helical structures could be formed in a diastereoselective manner by covalently attaching chiral units to the skeleton ( 1’2H and 1’Zn ). 1Zn was found to possess chiral recognition ability for amines. 相似文献
75.
Yusuke Nakajima Takeshi Kawano Yusuke Taki Chie Kojima 《Research on Chemical Intermediates》2018,44(8):4745-4754
Collagen is a major component of the extracellular matrix, and collagen gels have been used as cell scaffolds. We previously prepared gold nanoparticle (AuNP)-embedded collagen gels (AuCol) to serve as cell scaffolds that were sensitive to visible light. We performed single cell detachment from this cell scaffold using a microscope equipped with a laser irradiation system. In the present study, we adjusted hydrogel thickness and AuNP concentration in AuCol, with a goal of improving cell detachment efficiency. Thin hydrogels became blackened after the laser irradiation, and thick hydrogels with high AuNP concentrations were not permeable to the laser light. We, therefore, prepared bilayer gels, composed of AuCol as the upper layer and intact collagen gel (Col) as the bottom layer. These bilayer gels allowed more effective cell detachment, because they were thick and optically transparent. Our results indicated that an AuCol/Col ratio of 2 enabled the highest cell detachment efficiency. Essentially, no cell damage was observed in our system, suggesting that this is a cell-friendly single cell separation system. 相似文献
76.
Satoshi Goshima Masayuki Kanematsu Hiroshi Kondo Yusuke Tsuge Haruo Watanabe Yoshimune Shiratori Minoru Onozuka Noriyuki Moriyama 《Magnetic resonance imaging》2009,27(9):1230-1235
The purpose of this study was to compare observer interpreted steady-state coherent coronal images and gadolinium-enhanced axial images in terms of the detection and grading of esophageal varices. Magnetic resonance imaging (MRI) and gastrointestinal endoscopy were performed within 2 weeks in 90 patients with chronic liver damage, including 55 with untreated esophageal varices, for periodic screening purposes. Two blinded readers retrospectively reviewed T1- and T2-weighted images with gadolinium-enhanced (gadolinium image set) and steady-state coherent (coherent image set) images. Sensitivity for the detection of esophageal varices was higher (P<.001) in the gadolinium image set (76%) than in the coherent image set (35%); on the other hand, specificity was higher (P<.001) in the coherent image set (91%) than in the gadolinium image set (66%). Furthermore, area under the ROC curve was higher for the gadolinium image set (Az=0.823) than the coherent image set (Az=0.761) (P=.48). Moderate and weak positive correlations with endoscopic grades were found for the gadolinium image (r=0.48, P<.01) and coherent image sets (r=0.34, P=.018). The addition of steady-state coherent imaging to the current routine liver imaging protocol did not improve the detection or grading of esophageal varices, whereas gadolinium-enhanced imaging was found to be potentially valuable. Nevertheless, endoscopy was confirmed to be mandatory in patients with esophageal varices suspected by MRI of the liver. 相似文献
77.
Akiko Takeda Katsuki Fujisawa Yusuke Fukaya Masakazu Kojima 《Journal of Global Optimization》2002,24(2):237-260
As computing resources continue to improve, global solutions for larger size quadrically constrained optimization problems become more achievable. In this paper, we focus on larger size problems and get accurate bounds for optimal values of such problems with the successive use of SDP relaxations on a parallel computing system called Ninf (Network-based Information Library for high performance computing). 相似文献
78.
A method to synthesize a computer-generated hologram (CGH) of real-existing objects from projection images is proposed. Different from other similar methods, our method enables the synthesis of a CGH with only one-dimensional (1-D) mechanical scanning of the objects. Our method is connected with the three-dimensional (3-D) Fourier spectrum of the objects by the 3-D central slice theorem (CST). Two efficient recording techniques for projection images and numerical experiments to verify our principle is discussed. A comparison between the two techniques is also presented from the viewpoint of diffraction efficiency. © 2005 The Optical Society of Japan 相似文献
79.
Inoue Y Nomura Y Nakaoka T Watanabe M Kiryu S Okubo T Ohtomo K 《Magnetic resonance imaging》2005,23(5):641-645
The aim of this study was to investigate the effect of temporal resolution on the estimation of left ventricular (LV) function by cardiac magnetic resonance (MR) imaging using a steady-state free precession (SSFP) sequence. Left ventricular function was assessed by cine MR imaging using a segmented SSFP sequence in 10 healthy volunteers. Views per segment (VPS) were set at 8 and 20, resulting in high and low true temporal resolution, respectively. Irrespective of VPS, images were reconstructed at 40 cardiac phases, providing high apparent temporal resolution. Data were analyzed using 40, 20 and 10 phases to simulate different apparent temporal resolutions. Increasing the cardiac phases used for analysis slightly decreased mean end-systolic volume (ESV) and slightly increased mean ejection fraction (EF). No substantial difference in estimates of end-diastolic volume (EDV) was found between VPSs of 8 and 20. Imaging with a VPS of 20 yielded a larger ESV and smaller EF than imaging with a VPS of 8 when 40 phases were used. In conclusion, low true temporal resolution causes overestimation of ESV and underestimation of EF. Improvement of apparent temporal resolution mildly reduces but does not eliminate the errors caused by low true temporal resolution. 相似文献
80.
In the literature, there are numerous studies of one-dimensional discrete-time quantum walks (DTQWs) using a moving shift operator. However, there is no exact solution for the limiting probability distributions of DTQWs on cycles using a general coin or swapping shift operator. In this paper, we derive exact solutions for the limiting probability distribution of quantum walks using a general coin and swapping shift operator on cycles for the first time. Based on the exact solutions, we show how to generate symmetric quantum walks and determine the condition under which a symmetric quantum walk appears. Our results suggest that choosing various coin and initial state parameters can achieve a symmetric quantum walk. By defining a quantity to measure the variation of symmetry, deviation and mixing time of symmetric quantum walks are also investigated. 相似文献