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991.
992.
针对具有应用价值的卤代乙酸胍(GXA)非线性光学(NLO)晶体研究不系统的问题,设计了系列三卤代和系列氯代的乙酸胍(GAc)体系,通过量子化学计算研究了系列GXA的结构、NLO性质和构效关系,探讨了卤代效应可能的影响机理。结果表明,卤代原子显著地改变了GXA分子构象,并通过不同方式参与强氢键作用来影响超分子堆积。卤代主要通过影响GXA分子的LUMO来改变其能隙(Egap)。GXA的平均偶极矩(μtotal)和平均极化率<α>随卤原子数量以及半径的增大而增大。超极化率总体上相对于GAc降低,但影响复杂,其中,平均第1超极化率(βtotal)随卤原子数量的增多而降低,平均第2超极化率(<γ>)则随卤原子的变大而显著增强。此外,并未发现Egap与μtotal及<γ>之间存在明显的相关性。 相似文献
993.
Kai Lu Yang Lü Youxiang Bai Jueru Zhang Nanxi Bie Yongsheng Ren Yulong Ma 《中国化学工程学报》2020,28(4):969-979
Zero liquid discharge (ZLD) treatment and reuse equipment of high salinity wastewater in coal-chemical industry often occur in various types of blockage problems because of high salt content, affecting the long-term stability of the device. In this study, the effects of solution temperature, steel, reaction time and wall roughness on fouling were investigated. The changes in the contents of fouling and fouling substances were qualitatively and quantitatively analyzed by XRD and EDS respectively, and the formation of scale was observed by SEM. The results show that with temperature increasing, Q235 steel is the most difficult to scale. Scaling rate of all salt scales reaches a maximum after 12 h, and the fouling rate decreases significantly from 12 to 48 h. It gradually stabilizes at 48 to 96 h. With the roughness increasing, the thickness of fouling layer increases, and a linear relationship is presented for 1 to 10 h. By comparing actual and simulated wastewater scaling rates, the relationship between actual and simulated wastewater scaling rates is y=ax-0.494. The composition of the scale was analyzed, calcium carbonate is the main product and increases with fouling time. Based on the above-mentioned results combining literatures, the hybrid prediction model with calcium carbonate as the main product is put forward. It is discussed microscopically that calcium carbonate is converted from aragonite and vaterite in a thermodynamically metastable state to calcite in a thermodynamically stable state. 相似文献
994.
《Ceramics International》2020,46(9):13442-13448
In current study, gadolinium oxide was heterogeneously formed on the surface of iron oxide nanoparticles and further modified with dextrose capping agent to be used in biomedical applications, especially for contrast enhancement in MR images. First, two types of iron oxide nanoparticles were prepared at 25 and 80 °C via simple coprecipitaion method. Then, gadolinium oxide nanoparticles were synthesized through a consecutive precipitation process on previously formed iron oxide seeds in an aqueous media and subsequent annealing at 300 °C. Finally, dextrose was used as capping agent to stabilize nanocomposites in a colloidal suspension. X-ray diffraction (XRD), Scanning and Transmission electron microscopy, Dynamic Laser Scattering (DLS), Fourier-Transform Infrared Spectroscopy (FTIR), and Magnetometery (VSM) techniques were employed for nanocomposites investigation and MTT-assay method used for viability assessment of colloidal samples. Measurements based on Scherrer equation from XRD patterns showed that increasing coprecipitation temperature resulted bigger iron oxide crystallites. The iron oxide crystallite size was increased from 15.1 to 28.1 nm. Precipitation process led to gadolinium oxide formation with 30.7 and 38.8 nm crystallite sizes, respectively. TEM images revealed that iron oxide agglomerates were encapsulated in gadolinium oxide surroundings. Hydrodynamic size of the coated nanoparticles with dextrose was 208 and 247 nm. In VSM examinations, nanocomposites did not display coercive field and the saturation magnetization was 1.93 emu/g. MTT-assay results showed 80% viability in 285 μg nanocomposites containing 96.9 μg [Fe] and 11.4 μg [Gd]. 相似文献
995.
Application of graphene requires a high-yield, low-cost, scalable production method, but it remains highly challenging. We here report a water-phase technique to produce few-defect graphene nanosheets (FGS) with a high exfoliation yield (92%), based on the chemically expanded graphite with ultrahigh specific surface areas, and demonstrate the application in graphene-polymer nanocomposites. The exfoliated FGS has low degree of oxidation and preserves good mechanical and electrical properties, revealing promising potential for improving comprehensive properties of polymer composites. When 0.5 wt% FGS was incorporated to poly(methyl methacrylate) (PMMA), the 5% weight loss temperature and storage modulus increase by 87°C and 21%, respectively, relative to the neat polymer. With increasing the content of FGS to 4.6 wt%, the glass transition temperature of the composite increases by 25°C. In addition, the composites show a percolation threshold as low as 0.25 vol% and excellent electrical conductivity (50 S/m for 2.7 vol% FGS-PMMA composite). 相似文献
996.
《Ceramics International》2020,46(17):26675-26681
DyCrxFe(1-x)O3 (0 ≤ x ≥ 0.4) nanoparticles were prepared using facile chemical route. Structural and morphological evaluation was carried out using X-ray diffraction (XRD) and electron microscopy. Formation of orthorhombic DyFeO3 nanoparticles was confirmed by XRD with crystallite size of 9–10 nm. FESEM images revealed nearly spherical morphology of the fabricated nanoparticles. Energy dispersive X-ray (EDX) technique was employed to confirm the presence of Dy, Cr, Fe and O elements in DyCrxFe(1-x)O3 nanoparticles. FTIR studies illustrated the presence of characteristics stretching and bending vibrations. UV–visible spectroscopy was used to analyze the photocatalytic performance of the DyFeO3 and Cr-substituted DyFeO3 nanoparticles and optical band gap measurements. Photocatalytic activities of the prepared substituted and un-substituted DyFeO3 nanoparticles were conducted using three different dyes. These dyes were (i) methyl orange, (ii) rhodamine B and (iii) methylene blue. Lower band gap and higher photocatalytic performance was observed for Cr-substituted DyFeO3 nanoparticles with methylene blue dye. 相似文献
997.
为减少团聚,提高石墨烯在涂层中的分散性,研究采用纳米分散技术预先制备了石墨烯分散液,再将其分散至环氧树脂中获得石墨烯改性复合涂层。通过对石墨烯含量为 0、0.3%、0.6%的复合涂层进行盐水浸泡、盐雾、阴极剥离实验及电化学性能测试,证明石墨烯的加入显著增强了涂层的防护性能。石墨烯复合涂层在 3.5%盐水中浸泡 1 008 h后,涂层低频阻抗仍大于 106 Ω·cm2比未添加石墨烯的涂层提高了 3个数量级,且盐雾实验 6 000 h后涂层表面仍保持完好;含 0.6%石墨烯,的涂层耐蚀行为劣于石墨烯含量为 0.3%的涂层。 相似文献
998.
石油石化工业的发展对泵的需求 总被引:2,自引:0,他引:2
论述了我国石油石化工业的现状及发展趋势,并重点介绍了我国石油石化工业中泵的市场需求及应用. 相似文献
999.
1000.
以CoCl2和Na2S为试剂,采用改进的化学浴沉积法在玻璃衬底上制备出了CoS薄膜,并分别以偏光显微镜和LCR仪对样品的形貌和介电性质进行了研究。 相似文献