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991.
Miao Feng Yu Chen Lingling Gu Jinrui Bai Hongbing Zhan 《European Polymer Journal》2009,45(4):1058-4314
The fabrication of nanocomposites by covalent inclusion of inorganic nanoparticles in an organic polymer matrix is highly topical and may find applications in the electronics, optics and energy sectors. Incorporation of CdS nanoparticles into the polyacrylonitrile (PAN) matrices could be expected to display improved or enhanced optoelectronic and optical properties. Using a newly synthesized RAFT agent, i.e., CdS-DDAT nanoparticles (DDAT: S-1-Dodecyl-S′-(α, α′-dimethyl-α′′-acetic acid) trithiocarbonate), CdS covalently functionalized polyacrylonitrile (CdS-PAN) nanocomposite material was prepared in the presence of small amount of AIBN under ultrasonic radiation. This material, which exhibits an induced positive nonlinear absorption of incident light, has been well-characterized by a variety of physical techniques such as GPC, UV/vis, FT-IR, TGA, XRD and Z-scan. 相似文献
992.
993.
本文利用凸刻画系数和正规结构系数,詹姆斯型常数和García-Falset系数之间的关系式,得到了空间上集值非扩张映射存在不动点的一些充分条件,这些结论不仅改进了一些文献中的结果,而且也对一些公开问题给出了解答. 相似文献
994.
Preparation and in vitro evaluation of an ultrasound-triggered drug delivery system: 10-hydroxycamptothecin loaded PLA microbubbles 总被引:1,自引:0,他引:1
Hou Z Li L Zhan C Zhu P Chang D Jiang Q Ye S Yang X Li Y Xie L Zhang Q 《Ultrasonics》2012,52(7):836-841
10-Hydroxycamptothecin (HCPT) loaded PLA microbubbles, used as an ultrasound-triggered drug delivery system, were fabricated by a double emulsion-solvent evaporation method. The obtained microbubbles were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and confocal laser scanning microscope (CLSM). In addition, the effect of diagnostic ultrasound exposure on BEL-7402 cells combined with HCPT-loaded PLA microbubbles was evaluated using cytotoxicity assay, CLSM and flow cytometry (FCM). It was found that the HCPT-loaded PLA microbubbles showed smooth surface and spherical shape, and the drug was amorphously dispersed within the shell and the drug loading content reached up to 1.69%. Nearly 20% of HCPT was released upon exposure to diagnostic ultrasound at frequency of 3.5 MHz for 10 min. Moreover, HCPT fluorescence in the cells treated only with the HCPT-loaded PLA microbubbles was discernible, but less intense, while those treated with the microbubbles in conjunction with ultrasound exposure was evident and intense, indicating an increased cellular uptake of HCPT by ultrasound exposure. Cytotoxicity test on BEL-7402 cells indicated that the HCPT-loaded PLA microbubbles combined with ultrasound exposure were more cytotoxic than the microbubbles alone. The results suggest that the combination of drug loaded PLA microbubbles and diagnostic ultrasound exposure exhibit an effective intracellular drug uptake by tumor cells, indicating their great potential for antitumor therapy. 相似文献
995.
Effects of wet-pressing-induced fiber hornification on enzymatic saccharification of lignocelluloses
This article reports the effect of wet-pressing-induced fiber hornification on enzymatic saccharification of lignocelluloses.
A wet cellulosic substrate of bleached kraft eucalyptus pulp and two wet sulfite-pretreated lignocellulosic substrates of
aspen and lodgepole pine were pressed to various moisture (solids) contents by variation of pressing pressure and pressing
duration. Wet pressing reduced substrate moisture content and produced irreversible reduction in fiber pore volume—fiber hornification—as
reflected in reduced water retention values (WRVs), an easily measurable parameter, of the pressed substrates. Wet pressing
resulted in a reduction in substrate enzymatic digestibility (SED) by approximately 20% for the two sulfite-pretreated substrates
when moisture content was reduced from approximately 75% to 35%. The reduction in SED for the cellulosic substrate was less
than 10% when its moisture content was reduced from approximately 65% to 35%. The results indicated that reduction in SED
is negligible when samples were pressed to solids content of 40% but observable when pressed to solids content of 50%. It
was also found that WRV can correlate to SED of hornified substrates resulting from the same never-dried or pressed sample
independent of the hornification process (e.g., pressing or drying). This correlation can be fitted using a Boltzmann function.
Cellulase adsorption measurements indicated that wet-pressing-induced fiber hornification reduced cellulose accessibility
to cellulase. The results obtained in this study provide guidelines to high-solids enzymatic saccharification of pretreated
biomass. 相似文献
996.
997.
998.
Wang Yao Chuan-Jun Lu Li-Wen Zhan Yi Wu Dr. Jia Feng Prof. Dr. Ren-Rong Liu 《Angewandte Chemie (International ed. in English)》2023,62(21):e202218871
The catalytic asymmetric construction of N−N atropisomeric biaryls remains a formidable challenge. Studies of them lag far behind studies of the more classical carbon-carbon biaryl atropisomers, hampering meaningful development. Herein, the first palladium-catalyzed enantioselective C−H activation of pyrroles for the synthesis of N−N atropisomers is presented. Structurally diverse indole-pyrrole atropisomers possessing a chiral N−N axis were produced with good yields and high enantioselectivities by alkenylation, alkynylation, allylation, or arylation reactions. Furthermore, the kinetic resolution of trisubstituted N−N heterobiaryls with more sterically demanding substituents was also achieved. Importantly, this versatile C−H functionalization strategy enables iterative functionalization of pyrroles with exquisite selectivity, expediting the formation of valuable, complex, N−N atropisomers. 相似文献
999.
Dr. Fukai Xie Zhan Mao Dr. Dennis P. Curran Hongliang Liang Dr. Wen Dai 《Angewandte Chemie (International ed. in English)》2023,62(39):e202306846
Although the development of radical chain and photocatalytic borylation reactions using N-heterocyclic carbene (NHC)-borane as boron source is remarkable, the persistent problems, including the use of hazardous and high-energy radical initiators or the recyclability and photostability issues of soluble homogeneous photocatalysts, still leave great room for further development in a sustainable manner. Herein, we report a conceptually different approach toward highly functionalized organoborane synthesis by using recoverable ultrathin cadmium sulfide (CdS) nanosheets as a heterogeneous photocatalyst, and a general and mild borylation platform that enables regioselective borylation of a wide variety of alkenes (arylethenes, trifluoromethylalkenes, α,β-unsaturated carbonyl compounds and nitriles), alkynes, imines and electron-poor aromatic rings with NHC-borane as boryl radical precursor. Mechanistic studies and density functional theory (DFT) calculations reveal that both photogenerated electrons and holes on the CdS fully perform their own roles, thereby resulting in enhancement of photocatalytic activity and stability of CdS. 相似文献
1000.
Yu-Li Liu Dr. Shun-Ze Zhan Jing-Xuan Sun Prof. Dr. Hong Cai Zhuo-Li Yuan Hai-Feng Zhang Mian Li Prof. Dr. Li Dang Dr. Shao-Fei Ni Prof. Dr. Seik Weng Ng Prof. Dr. Weigang Lu Prof. Dr. Dan Li 《Angewandte Chemie (International ed. in English)》2023,62(33):e202306748
Two metallofullerene frameworks (MFFs) constructed from a penta-shell Keplerate cuprofullerene chloride, C60@Cu24@Cl44@Cu12@Cl12, have been successfully prepared via a C60-templated symmetry-driven strategy. The icosahedral cuprofullerene chloride is assembled on a C60 molecule through [η2-(C=C)]−CuI and CuI−Cl coordination bonds, resulting in the penta-shell Keplerate with the C60 core canopied by 24 Cu, 44 Cl, 12 Cu and 12 Cl atoms that fulfill the tic @ rco @ oae @ ico @ ico penta-shell polyhedral configuration. By sharing the outmost-shell Cl atoms, the cuprofullerene chlorides are connected into 2D or 3D ( snf net) frameworks. TD-DFT calculations reveal that the charge transfer from the outmost CuI and Cl to C60 core is responsible for their light absorption expansion to near-infrared region, implying anionic halogenation may be an effective strategy to tune the light absorption properties of metallofullerene materials. 相似文献