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891.
Inspired by structures of antenna-reaction centers in photosynthesis, the complex micelle was prepared from zinc tetra-phenyl porphyrin (ZnTPP), fullerene derivative (PyC60) and poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-b-PCL). The core-shell structure made the hydrophobic donor-acceptor system work in aqueous. In micellar core, coordination interaction occurred between ZnTPP and PyC60 molecules which ensured the enhanced energy migration from the donor to the acceptor. The enhanced interaction between porphyrin and fullerene was confirmed by absorption, steady-state fluorescence and transient fluorescence. The generation of singlet oxygen and superoxide radical was detected by iodide method and reduction of nitro blue tetrazolium, respectively, which confirmed that electron transfer reaction in the complex micellar core occurred. Moreover, the complex micelle exhibited effective electron transfer performance in photodebromination of 2,3-dibromo-3-phenylpropionic acid. The complex micellar structure endowed the donor-acceptor system with improved stability under irradiation. This strategy could be helpful for designing new electron transfer platform and artificial photosynthetic system. 相似文献
892.
A setup of blown film machine combined with in situ synchrotron radiation X-ray diffraction measurements and infrared temperature testing is reported to study the structure evolution of polymers during film blowing. Two homemade auto-lifters are constructed and placed under the blown machine at each end of the beamline platform which move up and down with a speed of 0.05 mm/s bearing the 200 kg weight machine. Therefore, structure development and temperature changes as a function of position on the film bubble can be obtained. The blown film machine is customized to be conveniently installed with precise servo motors and can adjust the processing parameters in a wide range. Meanwhile, the air ring has been redesigned in order to track the structure information of the film bubble immediately after the melt being extruded out from the die exit. Polyethylene (PE) is selected as a model system to verify the feasibility of the apparatus and the in situ experimental techniques. Combining structure information provided by the WAXD and SAXS and the actual temperature obtained from the infrared probe, a full roadmap of structure development during film blowing is constructed and it is helpful to explore the molecular mechanism of structure evolution behind the film blowing processing, which is expected to lead to a better understanding of the physics in polymer processing. 相似文献
893.
Yujuan Li Tiecheng Wang Yiran Meng Guangzhou Qu Qiuhong Sun Dongli Liang Shibin Hu 《Plasma Chemistry and Plasma Processing》2017,37(6):1621-1634
Air atmospheric dielectric barrier discharge plasma (DBD) was attempted to pretreat wheat seed to improve its germination and growth in this study. The effects of the DBD plasma treatment on the wheat seed germination, seedling growth, osmotic-adjustment products, lipid peroxidation level, and antioxidant enzymes activity were investigated. The experimental results showed that the DBD plasma treatment with an appropriate time scale could promote the wheat seed germination and seedling growth. The germination potential, germination rate, germination index, and vigor index increased by 26.7, 9.1, 16.9, and 46.9% after 7 min’s DBD plasma treatment, respectively; the root length, shoot length, fresh weight, and dry weight of the seedlings also increased after the DBD plasma treatment. The osmotic-adjustment products, proline and soluble sugar contents, in the wheat seedlings were significantly enhanced after the DBD plasma treatment with an appropriate time scale, while the malondialdehyde content decreased. Moreover, the activities of superoxide dismutase and peroxidase also increased after the DBD plasma treatment. The DBD plasma treatment led to etching effect on the wheat seed coat, resulting in the improvement of its water absorption capacity. 相似文献
894.
柔性扑翼的气动特性研究 总被引:6,自引:0,他引:6
以往扑翼的气动力计算研究都很少考虑扑翼的柔性,而在鸟的扑翼动作中,在外加气动力和鸟自身的扑动力作用下,扑翼的柔性变形相当大。本文在原有匀速刚性模型的基础上,提出考虑了扑翼扑动速率变化和形状变化的扑翼分析模型,使之更接近鸟翼柔性扑动真实情况。通过计算分析气动特性发现,控制适当的话,柔性变形能大大改善扑翼的气动性能。本文通过模拟鸟扑翼的柔性运动,计算了时柔性扑翼气动力以及平均升力系数和平均推力系数随着扑动角、倾斜角等参数变化的情况,从而从气动的角度解释了为什么鸟在不同的飞行阶段扑翼规律各不相同,并为柔性扑翼飞行器的设计提供了理论依据。 相似文献
895.
896.
Zhu Zhengyou Ding Rui 《Acta Mechanica Solida Sinica》1995,8(4):356-363
From the point of view of dynamics,the phenomenon of mode jumpingin the imperfect pitchfork problem is discussed.The dynamical mechanism of modeljumping of structures,such as plate and shell,that is brought about by the extremurninstability,is explained.Finally,we give numerical simulation to show the validity ofour results. 相似文献
897.
Syntheses and X‐ray structural characterizations of two new Cu(II) complexes Cu(tfbz)2(Htfbz)2(phen) ( 1 ) (Htfbz=2,4,5‐trifluorobenzoic acid, phen=1,10‐phenanthroline) and [Cu(pfbz)2(phen)]2(Hpfbz)2 ( 2 ) (Hpfbz=pentafluorobenzoic acid) are reported. The first complex crystallizes in the monoclinic space group C2/c with the crystal cell parameters a=1.9903(4) nm, b=1.3688(3) nm, c=1.3623(3) nm, β=97.90(3)°, V=3.6762(13) nm3 and Z=4. The second complex crystallizes in the triclinic space group P‐1 with the crystal cell parameters a=1.7965(4) Å, b=1.9236(2) Å, c=2.0916(2) Å, α=110.156(2) °, β=105.040(3) °, γ=98.123(3) °, V=6.3372(17) nm3 and Z=4. The crystallographic analyses revealed that F···H–C hydrogen bonds in both complexes lead to formation of infinite three‐dimensional supramolecular networks. A large number of F···F interactions in complex 2 ensure the stability of intricate crystal structure. 相似文献
898.
<正>The synthesis and mesomorphic properties of a new class of liquid crystalline cyclotriphosphazenes with rigid cyanostilbene groups and flexible alkoxy groups are reported.The thermal behaviors of cyclotriphosphazene derivatives 5a-5d are studied by the means of differential scanning calorimetry,polarizing optical microscopy.Nematic phases were observed in compounds 5a-5d both on heating and cooling.The clear temperatures of compounds 5a-5d slightly increased with increasing length of terminal alkyl chain.Compounds 5a-5d showed different mesogenic region from minimum 5℃to maximum 142℃. 相似文献
899.
<正>Two new homoisoflavanones were isolated from the rhizomes of Polygonatum odoratum(Mill.) Druce and their structures were elucidated as(3R)-5,7-dihydroxy-8-methoxy-3-(4-methoxybenzyl)-6-methylchrom-an-4-one(1) and(3R)-5,7,8-trihydroxy-3-(4- hydroxybenzyl)-6-methylchroman-4-one(2),on the basis of spectral analysis. 相似文献
900.
<正>Nitration of 4,4'-biphenyldicarboxylic acid(BPDC) was studied and an aromatic carboxylic acid containing two nitro groups was synthesized and characterized through elemental analysis and IR spectra.Crystal structure of DNBPDC(DNBPDC=2,2'- dinitro-4,4'-biphenyldicarboxylic acid) was determined by X-ray single crystal diffraction and the thermal decomposition was carried out through DSC and TG-DTG analyses. 相似文献