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21.
Shiou-Shiow Farn Yen-Buo Lai Kuo-Fong Hua Hsiang-Ping Chen Tzu-Yi Yu Sheng-Nan Lo Li-Hsin Shen Rong-Jiun Sheu Chung-Shan Yu 《Molecules (Basel, Switzerland)》2022,27(9)
A small fenbufen library comprising 18 compounds was prepared via Suzuki Miyara coupling. The five-step preparations deliver 9–17% biphenyl compounds in total yield. These fenbufen analogs exert insignificant activity against the IL-1 release as well as inhibiting cyclooxygenase 2 considerably. Both the para-amino and para-hydroxy mono substituents display the most substantial COX-2 inhibition, particularly the latter one showing a comparable activity as celecoxib. The most COX-2 selective and bioactive disubstituted compound encompasses one electron-withdrawing methyl and one electron-donating fluoro groups in one arene. COX-2 is selective but not COX-2 to bioactive compounds that contain both two electron-withdrawing groups; disubstituted analogs with both resonance-formable electron-donating dihydroxy groups display high COX-2 activity but inferior COX-2 selectivity. In silico simulation and modeling for three COX-2 active—p-fluoro, p-hydroxy and p-amino—fenbufens show a preferable docking to COX-2 than COX-1. The most stabilization by the p-hydroxy fenbufen with COX-2 predicted by theoretical simulation is consistent with its prominent COX-2 inhibition resulting from experiments. 相似文献
22.
B. Chai S.-C. Zhang C.-R. Qiu H.-B. Zhang Y.-X. Lai Q. Xin 《Journal of Infrared, Millimeter and Terahertz Waves》2007,28(6):423-432
A linear theory based on Maxwell-Vlasov equations and the Laplace transform is presented to describe the large-orbit coaxial-waveguide cyclotron autoresonance maser (CARM) amplifier. A 35-GHz, TE5,1-mode large-orbit coaxial-waveguide CARM amplifier is specifically analyzed. Good agreement between the linear theory and the nonlinear simulations is found in the exponentially growing region of the wave. Results show that the operating magnetic field and the electron-beam energy and average radius substantially affect the power, and especially, a small beam current may be unsuitable to a large-orbit CARM amplifier operation. 相似文献
23.
The synthesis of novel symmetrical liquid crystalline compounds based on 5-methyl-5-[2-(4-alkyloxyphenyl)-2-hydroxyethyl]-2,2-bipyridines is reported, together with some physical properties. Although the chelating head-groups are connected via a chiral sp3 carbon atom, all the materials are mesomorphic. Intermolecular hydrogen bonding between pyridino and hydroxy fragments in the mesophases is made apparent by FTIR spectroscopy. 相似文献
24.
A tunable optical rail is embedded into the cavity of a nonlinear-polarization-rotation(NPR) mode-locked fiber laser to generate a sampling pulse with different repetition frequencies and realize bit-rate-adaptive software synchronous optical sampling.Two ultrashort pulses(20.26677 and 20.22900 MHz) are derived,and a 100-MHz data signal is sampled twice with these pulses based on sum-frequency generation(SFG) in periodically poled lithium niobate(PPLN).The eye diagram is successfully recovered,and an estimated bit rate of 102.22 MHz is derived.This method is feasible for bit rates ranging from 200 MHz to 1 GHz,with <3% relative error. 相似文献
25.
Investigation of growth behavior of Al-Cu intermetallic compounds in Cu wire bonding 总被引:1,自引:0,他引:1
In this work, we investigate the intermetallic compound formation in Cu wire bonded device. Voids near the Cu side at the bond interface are clearly seen. Nevertheless, these voids do not seem to interfere with the function of the unit. High temperature storage test (HTST) results show that there are Al2Cu and AlCu in the damaged unit while Al2Cu and Al4Cu9 appear in the good unit. The results clearly show that the Al layer is exhausted in the damaged unit while those with Al4Cu9 on the Cu side pass HTST with unconsumed Al. Theoretical calculations indicate that AlCu and Al4Cu9 are energetically more favorable than Al2Cu, which is consistent with the reported IMC forming sequence. Formation energy of AlCu is compatible but slightly lower to that of Al4Cu9, suggesting AlCu tends to be the most stable phase among all. The reason why the Al layer is completely consumed in one case and some Al layer remains in the other is due to the fact that the formation of AlCu requires more than twice the amount of Al than Al4Cu9 for the same amount of Cu consumed. The complete consumption of Al is proposed as the reason responsible for the failure of the damaged unit. 相似文献
26.
Triphenylamine derivatized phenylacetylene macrocycle with large two-photon absorption cross-section
Zhen Fang Marek SamocRichard D. Webster Anna SamocYee-Hing Lai 《Tetrahedron letters》2012,53(36):4885-4888
A phenylacetylene macrocycle (PAM) derivative containing triphenylamine as the framework was synthesized in one-step Sonogashira coupling. The photophysical and electrochemical properties were investigated in details. This hexamer shows significant enhancement in two-photon absorption cross-section relative to reported PAM derivatives. 相似文献
27.
Application of magnetic nanoparticles for the extraction of radium-226 from water samples 总被引:1,自引:0,他引:1
Natalie Mesnic Baki Sadi Chunsheng Li Edward Lai 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(3):1501-1509
Bare (unmodified) and crown ether (CE)-modified Fe3O4 magnetic nanoparticles (MNPs) were investigated for the rapid extraction of 226Ra from water samples. It involved synthesizing the MNPs, introducing them into the sample solutions, ultrasonicating and agitating the suspension, magnetically separating the nanoparticles from solution, and measuring the 226Ra content in the supernatant. Experimental parameters such as salt choice, salt concentration and pH were optimized to achieve maximum extraction of 226Ra onto the MNPs. 226Ra content was determined using a Hidex 300SL liquid scintillation counter with α/β separation capability, or a gamma spectrometric detection system. The bare Fe3O4 nanoparticles showed significant pH dependence for the extraction of 226Ra from an aqueous solution over a pH range of 2–10. They gave an extraction of 95 ± 1 and 98 ± 1 % at pH 9 in 0.1 M NaCl and 0.1 M NaClO4, respectively, whereas an extraction of 8–24 % was obtained, over the pH ranges from 2 to 5. The CE-modified MNPs yielded extraction efficiencies as high as 99 ± 1 % in the presence of 0.01 M picric acid at pH 4. This study demonstrates that the surface functionalization of Fe3O4 MNPs with suitable ligand modification can offer a selective mode of extraction for 226Ra in the presence of its daughter progenies. 相似文献
28.
29.
Xiaoxiao Qu Weiwei Kang Changwei Lai Chuanxiang Zhang Suck Won Hong 《Molecules (Basel, Switzerland)》2022,27(3)
High-performance porous carbons derived from tea waste were prepared by hydrothermal treatment, combined together with KOH activation. The heat-treatment-processed materials possess an abundant hierarchical structure, with a large specific surface of 2235 m2 g−1 and wetting-complemental hydrophilicity for electrolytes. In a two-electrode system, the porous carbon electrodes’ built-in supercapacitor exhibited a high specific capacitance of 256 F g−1 at 0.05 A g−1, an excellent capacitance retention of 95.4% after 10,000 cycles, and a low leakage current of 0.014 mA. In our work, the collective results present that the precursor crafted from the tea waste can be a promising strategy to prepare valuable electrodes for high-performance supercapacitors, which offers a practical strategy to recycle biowastes into manufactured materials in energy storage applications. 相似文献
30.
Recently it has been suggested that zero quantum coherence in scalar coupled spin systems at thermal equilibrium can be created by a single non-selective pulse. In this note, it is shown that the proposed effect will be masked as a consequence of the failure of the conventional high-temperature approximation normally applied to the equilibrium spin density operator. For exacting experiments, its appears that the approximation (eq) ≈ 1-H
/kT may not suffice. 相似文献