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51.
Oil droplets containing surfactants and pesticides are expected to spread on a water surface, under the Marangoni effect, depending on the surfactant. Pesticides are transported into water through this phenomenon. A high-speed video camera was used to measure the movement of Marangoni ridges. Gas chromatography with an electron capture detector was used to analyze the concentration of the pesticide in water at different times. Oil droplets containing the surfactant and pesticide spread quickly on the water surface by Marangoni flow, forming an oil film and promoting emulsification of the oil–water interface, which enabled even transport of the pesticide into water, where it was then absorbed by weeds. Surfactants can decrease the surface tension of the water subphase after deposition, thereby enhancing the Marangoni effect in pesticide-containing oil droplets. The time and labor required for applying pesticides in rice fields can be greatly reduced by using the Marangoni effect to transport pesticides to the target. 相似文献
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Long Jiao Yanna Zhang Zhijun Du Xuemin Dai Hanfu Wang Zhixin Dong Haibo Yao Xuepeng Qiu 《Journal of polymer science. Part A, Polymer chemistry》2022,60(16):2454-2464
To tolerate high processing temperature during the fabrication of low-temperature polycrystalline silicon thin-film transistors (LTPS–TFT) in flexible OLED devices, the polyimide (PI) films, which are used as substrate, should have ultra-high glass transition temperature (Tg > 450°C) and ultra-low coefficient of thermal expansion (CTE at 0–5 ppm K−1). In this paper, two novel heterocyclic monomers, namely, N,N'-(xanthone-2,7-diyl)bis(4-aminobenzamide) (p-DAXBA) and N,N'-(xanthone-2,7-diyl)bis(3-aminobenzamide) (m-DAXBA), which contain a xanthone moiety, are prepared and polycondensed with pyromellitic dianhydride (PMDA), respectively. PI films (PIa and PIb) with intrinsic high Tg and low CTE are designed from the perspective of rigid conjugate xanthone structure and hydrogen bonding interaction. It is found that the PIa films prepared by p-DAXBA have better linear structure of molecular chains and show relatively higher Tg and lower CTE. The Tg of PIa-40 is greater than 450°C, and CTE can reach as low as 2.7 ppm K−1, tensile strength of 179 MPa, modulus of 5.67 GPa, indicating potential application prospect as a flexible OLED substrate. 相似文献
54.
Donglin Fu Xuemin Rao Jinyi Xu Genzoh Tanabe Osamu Muraoka Xiaoming Wu Weijia Xie 《Tetrahedron letters》2018,59(30):2876-2879
The first total syntheses of naturally occurring cyclodepsipeptides Hikiamides A–C are described. The key linear pentapeptide precursors, prepared efficiently via Fmoc-solid-phase synthesis, were cyclized in dilute solution to provide the target Hikiamides A–C. The structures of the synthetic Hikiamides A–C were characterized by NMR and HRMS spectroscopy which were in agreement with those of natural products. 相似文献
55.
Keke Chai Yihui Jiang Tianzhi Han Xuemin Duan Jintao Wang 《Transition Metal Chemistry》2018,43(8):657-664
Two mononuclear Pt(II) complexes, Pt(dbbpy)Cl2 (1) and [Pt(dbbpy)2](PF6)2 (2) (dbbpy?=?4,4′-ditertbutyl-2,2′-biyridine) were synthesized and characterized by single-crystal X-ray diffraction analysis, elemental analysis, 1H NMR, and ESI–MS. Their binding affinities for both double-stranded (DS) calf thymus DNA (ct-DNA) and G-quadruplex DNA (HT21 and BCL-2) were investigated. In addition to structural differences, complex 1 displayed higher binding affinity for DS ct-DNA, whereas positively charged complex 2 was selective for binding to G-quadruplex DNA over DS DNA. The time-dependent cleavage of supercoiled circular plasmid pBR322 DNA by 1 was observed using agarose gel electrophoresis, whereas complex 2 hardly cleaved DS DNA. Stabilization of G-quadruplex HT21 DNA by both complexes was assessed by PCR stop assays. Both complexes exhibited moderate activities for inhibition of topoisomerase I as well as modest antiproliferation activities toward cancer cells in CKK-8 assays. 相似文献
56.
Inside Cover: Peripheral Templation‐Modulated Interconversion between an A4L6 Tetrahedral Anion Cage and A2L3 Triple Helicate with Guest Capture/Release (Angew. Chem. Int. Ed. 7/2018) 下载免费PDF全文
57.
Peripheral Templation‐Modulated Interconversion between an A4L6 Tetrahedral Anion Cage and A2L3 Triple Helicate with Guest Capture/Release 下载免费PDF全文
Xuemin Bai Prof. Chuandong Jia Prof. Yanxia Zhao Dr. Dong Yang Shi‐Cheng Wang Prof. Anyang Li Prof. Yi‐Tsu Chan Prof. Yao‐Yu Wang Prof. Xiao‐Juan Yang Prof. Biao Wu 《Angewandte Chemie (International ed. in English)》2018,57(7):1851-1855
An anion‐coordination‐based A4L6 (“A” denotes anion and “L” is ligand) tetrahedral cage was constructed by a C2‐symmetric bis‐bis(urea) ligand and phosphate anion, which showed reversible interconversion with the A2L3 triple helicate as a response to the template, concentration, or solvent. Notably, an unusual “peripheral” templation was found to be critical to stabilize the tetrahedral structure. This peripheral effect was utilized to assemble an “empty” A4L6 cage that allows the multi‐stimuli‐controlled capture/release of biologically important species such as choline and acetylcholine. 相似文献
58.
Hydrogenated amorphous carbon films (a-C:H) were deposited on p-type silicon as well as silica substrates by pulsed laser deposition technique using a mixture of graphite and camphor powders. The Fourier transform infrared spectroscopy measurement revealed the presence of hydrogen in the a-C:H films. The optical properties and structure of the a-C:H film were investigated by UV-visible and Raman scattering spectroscopy. The formation of a heterojunction between the a-C:H film and silicon substrate was confirmed by the current-voltage (I-V) measurement. Furthermore, the structure of a-C:H/p-Si showed photovoltaic characteristics with an open-circuit voltage (Voc) of 0.4 V and short-circuit current density (Jsc) of about 15 mA/cm2 under AM1.5 (100 mW/cm2) illumination. From the calculation, the energy conversion efficiency and fill factor were found to be 2.1% and 0.38, respectively. The carbon layer contributed to the energy conversion efficiency, which was proved by the measurement of quantum efficiency. 相似文献
59.
60.
Oriented mesostructured silica films show potential for the design of nanostructured materials for applications in optics, electronics, and so on. In this report, we propose a new approach to control the orientation of mesochannels using a laser-modified polyimide surface. Pluronic 123 was employed as the structure agent, and mesostructured SBA-15-type silica film was prepared using dip- and spin-coating techniques. The orientation of the mesochannels was evaluated by in-plane X-ray diffraction (XRD) measurements. It was shown that the mesochannels were oriented along the surface microgrooves. The driving force for the orientation of the mesochannels is attributed to the confining effect of the surface microgrooves on the deposited mesochannels. 相似文献