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971.
A new kind of parallel finite-difference time-domain (FDTD) method is used to calculate and analyze the transmission properties of photonic crystal. The effectiveness and the accuracy of parallel FDTD method were proved by the typical two-dimensional sine wave. The result shows that parallel FDTD method, which can save time effectively in electromagnetic problems with large size and long time, performs as accurate as the series one. This method, whose results shows that the photonic band gap normalized frequency moves to the low-frequency direction with the enlargement of the section area of the square cylinder and that the band gap gets thinner, is applied to simulate and analyze the two-dimensional photonic crystal and gives calculating method and analyzing accordance to calculate and analyze large-sized photonic crystal structure. 相似文献
972.
Yusuke Inoue Hirofumi Hata Ai Nakajima Yuji Iwadate Gou Ogasawara Keiji Matsunaga 《Magnetic resonance imaging》2014
Purpose
To optimize the navigator-gating technique for the acquisition of high-quality three-dimensional spoiled gradient-recalled echo (3D SPGR) images of the liver during free breathing.Materials and methods
Ten healthy volunteers underwent 3D SPGR magnetic resonance imaging of the liver using a conventional navigator-gated 3D SPGR (cNAV-3D-SPGR) sequence or an enhanced navigator-gated 3D SPGR (eNAV-3D-SPGR) sequence. No exogenous contrast agent was used. A 20-ms wait period was inserted between the 3D SPGR acquisition component and navigator component of the eNAV-3D-SPGR sequence to allow T1 recovery. Visual evaluation and calculation of the signal-to-noise ratio were performed to compare image quality between the imaging techniques.Result
The eNAV-3D-SPGR sequence provided better noise properties than the cNAV-3D-SPGR sequence visually and quantitatively. Navigator gating with an acceptance window of 2 mm effectively inhibited respiratory motion artifacts. The widening of the window to 6 mm shortened the acquisition time but increased motion artifacts, resulting in degradation of overall image quality. Neither slice tracking nor incorporation of short breath holding successfully compensated for the widening of the window.Conclusion
The eNAV-3D-SPGR sequence with an acceptance window of 2 mm provides high-quality 3D SPGR images of the liver. 相似文献973.
Lunhong Ai 《Applied Physics A: Materials Science & Processing》2014,116(2):589-595
In heterostructured metal–semiconductor system, plasmonic metal nanostructures can cooperate with semiconductors to enhance the solar light harness and energy conversion. In this study, we report on the plasmonically photocatalytic system constructed by in situ growth of semiconductor on metal nanostructures with high performance and stability. A facile and rapid microwave-assisted route was first explored to synthesize Ag nanocrystals, and subsequently converting them to Ag–AgCl nanohybrids was realized by in situ chemical transformation strategy at room temperature. These Ag–AgCl nanohybrids were characterized by X-ray diffraction, scanning electronic microscopy, and UV–vis absorption spectroscopy. The resulting Ag–AgCl nanohybrids showed remarkable photocatalytic activity and excellent durability for the degradation of organic pollutants under visible light irradiation. This finding provides a new way to improve photocatalytic efficiency through controllable chemical transformation. 相似文献
974.
975.
For a sequence of approximate Dirac-harmonic maps from a closed spin Riemann surface into a stationary Lorentzian manifold with uniformly bounded energy, we study the blow-up analysis and show that the Lorentzian energy identity holds. Moreover, when the targets are static Lorentzian manifolds, we prove the positive energy identity and the no neck property.
相似文献976.
Yuan C. M. Hu X. Yuan F. Li Y. Wu X. H. Zhou C. S. Ai Y. T. Liu Y. Luo C. C. Qiao X. J. Li Z. J. 《Russian Journal of Coordination Chemistry》2019,45(11):824-829
Russian Journal of Coordination Chemistry - A new lanthanide coordination polymer (Ln-CP) based on Nd(III), [Nd2(Cptpy)2(Glu)2(H2O)2]n · 5n(H2O) (Ι) (HCptpy =... 相似文献
977.
Yeye Ai Dr. Yongguang Li Dr. Heidi Li-Ki Fu Dr. Alan Kwun-Wa Chan Prof. Vivian Wing-Wah Yam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(20):5251-5258
A n l -glutamine-derived functional group was introduced to the bis(arylalkynyl)platinum(II) bipyridine complexes 1 – 4 . The emission could be switched between the 3MLCT excited state and the triplet excimeric state through solvent or temperature changes, which is attributed to the formation and disruption of hydrogen-bonding, π–π stacking, and metal–metal interactions. Different architectures with various morphologies, such as honeycomb nanostructures and nanospheres, were formed upon solvent variations, and these changes were accompanied by 1H NMR and distinct emission changes. Additionally, yellow and red emissive metallogels were formed at room temperature due to the different aggregation behaviors introduced by the substituent groups on bipyridine. The thermoresponsive metallogel showed emission behavior with tunable colors by controlling the temperature. The negative Gibbs free-energy change (ΔG) and the large association constant for excimer formation have suggested that the molecules undergo aggregation through hydrogen-bonding, π–π, and metal–metal interactions, resulting in triplet excimeric emission. 相似文献
978.
Ke Chen Zhihao Bao Ai Du Xiurong Zhu Jun Shen Guangming Wu Zhihua Zhang Bin Zhou 《Journal of Sol-Gel Science and Technology》2012,62(3):294-303
A rapid and facile synthesis of resorcinol/formaldehyde cross-linked silica (RF/SiO2) aerogels was carried out in one pot based on an acid-catalyzed route, instead of the previously reported base-catalyzed
ones. The gelation time was reduced to several hours at room temperature while it took several days even under heating conditions
in the base-catalyzed ones. The interpenetrating network of RF/SiO2 aerogels showed similar porous structures with those of silica aerogels or RF aerogels. Their thermal conductivity was as
low as that of the typical glass wool materials. The mechanical properties are characterized by dynamic mechanical analysis
and compression testing. At room temperature, the results of compression testing show that the compressive Young’s modulus
or ultimate failure strength of RF/SiO2 aerogel specimen is higher than that of native SiO2 aerogels with a similar density. The one-pot method improves the efficiency and reduces the cost of RF/SiO2 aerogels. The hierarchical porous carbon monoliths are also converted from carbonized RF/SiO2 aerogels by an additional HF treatment. Hence, they could be further explored as multifunctional candidate materials for
thermal, mechanical, and electrochemical applications. 相似文献
979.
Ryo Yonenuma Ai Ishizuki Kazuhiro Nakabayashi Hideharu Mori 《Journal of polymer science. Part A, Polymer chemistry》2019,57(24)
Dipeptide diphenylalanine has attracted significant research interests because of its ability to self‐assemble into various nanostructures such as nanotubes, nanowires, and nanoribbons. In this article, we present the synthesis and self‐assembly of a novel diphenylalanine‐based homopolymer and block/random copolymers by the reversible addition–fragmentation chain transfer (RAFT) polymerization of an acrylamide having a dipeptide moiety. The RAFT polymerization of N‐acryloyl‐l ,l ‐diphenylalanine (A‐Phe‐Phe‐OH) afforded novel amino acid‐based polymers with predetermined molecular weights and relatively narrow‐molecular weight distributions. The hierarchical self‐assembled structures of poly(A‐Phe‐Phe‐OH), which involve nanorods, larger nanofiber‐like microcrystals, and fiber bundles, were characterized by atomic force microscopy (AFM), transmission electron microscopy, scanning electron microscopy, and dynamic light scattering measurements. The circular dichroic measurements of poly(A‐Phe‐Phe‐OH) revealed its characteristic chiroptical property, which is affected by the nature of the solvents and the addition of urea and salts via hydrophobic, hydrogen bonding, and electrostatic interactions. Thermo‐ and pH‐responsive block and random copolymers composed of A‐Phe‐Phe‐OH and N‐isopropylacrylamide were synthesized by RAFT polymerization, and the thermoresponsive properties and assembled structures of the resulting copolymers were investigated by AFM and turbidity measurements. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2562–2574 相似文献
980.
Youhua Tao Ling Ai Huiyu Bai Xiaoya Liu 《Journal of polymer science. Part A, Polymer chemistry》2012,50(17):3507-3516
Photocrosslinked hyaluronic acid/poly(vinyl alcohol)‐styrylpyridinium (HA/PVA‐SbQ) hydrogels were synthesized for controlled antitumor drug delivery. The photocrosslinking reaction was rapid, and the time required for completely converting into the insoluble hydrogels was less than 500 s on exposure to 5 mW/cm2 UV light irradiation. The resulting hydrogels exhibited sensitivity to the pH value of the surrounding environment. Scanning electron microscopic analysis revealed that the morphology and the pore size of the hydrogels could be controlled by changing the ratio of HA and PVA‐SbQ in the formulations. Paclitaxel (PTX)‐loaded hydrogel could also be formed rapidly by UV irradiation of a mixed solution of HA/PVA‐SbQ and PTX. Release profiles of PTX from the hydrogels showed pH‐dependent and sustained manner. Moreover, our data revealed that PTX released from the HA hydrogels remained biologically active and had the capability to kill cancer cells. In contrast, control groups of HA hydrogels without PTX did not exhibit any cytotoxicity. This study demonstrates the feasibility of using HA‐based hydrogels as a potential carrier for chemotherapeutic drugs for cancer treatments. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献