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排序方式: 共有3946条查询结果,搜索用时 15 毫秒
71.
郑孝英 《昆明冶金高等专科学校学报》2014,(5):57-60
采用反相悬浮法,通过环氧氯丙烷交联制备β-环糊精改性交联壳聚糖微球(CDS),用FTIR和SEM进行表征,研究其对甲基橙(MO)的吸附和缓释性能。考察吸附时间、溶液p H值、MO浓度、温度等因素对CDS微球吸附的影响,并与交联壳聚糖(CTS)微球进行比较。结果表明,在p H 4.0、交联CTS微球1h可达吸附平衡,而CDS 2 h达到平衡;吸附数据均符合Freundlich等温方程和二级动力学方程。 相似文献
72.
Rui Xu Jing Song Shijiao Zhao Lei Nie Changsheng Deng Shaochang Hao Xingyu Zhao Bing Liu Jingtao Ma 《Journal of the American Ceramic Society》2021,104(11):5489-5500
ZrO2 microspheres are widely used as a simulant of UO2 in the development of nuclear fuel. However, the cracking of ZrO2 microspheres prepared by internal gelation is still a challenge during drying and sintering processes. To address this issue, we designed and optimized the washing process for obtaining crack-free ZrO2 microspheres. Through thermogravimetric, infrared, Raman, BET, and SEM analysis, it is shown that the cracking of the microspheres is mainly related to the pores in microspheres. The washing solvent with low surface tension is used to reduce the effect of capillary force on pore shrinkage. Therefore, the optimal washing process was designed as trichloroethylene (TCE)—0.5 M NH3.H2O—Propylene glycol methyl ether (PM) and gel microspheres with a high specific surface area of 315.3 m2/g and pore volume of 0.4125 cm3/g were obtained. The characterizations also further showed that when the microspheres were dried and sintered, the water vapor and the decomposition gas of organic matter were completely released from the pores in the microspheres. Our new washing process could be directly extended for preparing crack-free ceramic microspheres by internal gelation. 相似文献
73.
Ahmed I. A. Abd El-Mageed Ahmed Esmail Shalan Lamiaa A. Mohamed Hisham A. Essawy Fouad Taha Amro K. F. Dyab 《Polymer Engineering and Science》2021,61(1):234-244
Styrene as a monomer was emulsified in water using several magnetite nanoparticles concentration and pH values. Emulsified styrene drops were used as templates for polymerization, in presence of water soluble free radical initiator, and formation of composite particles. Styrene template drops stabilization was verified by light as well as scanning electron microscopy imaging, which ensured the participation of the particles in building up a mechanical barrier to stop oil drops coalescence. Furthermore, the produced polystyrene composites were strongly attracted to an external magnet. The difference in particles size as a function of pH was elucidated using zeta potential measurements, which indicated dominance of pH on the hydrophilicity of the particles and consequently the extent of emulsification, which in turn affected the size of the obtained microspheres. Under some circumstances, capsules were formed instead of particles. Thereby, it can be concluded that the magnetic microspheres are optimally formed at pH 2.3 independently of the magnetite content used. 相似文献
74.
《Journal of the European Ceramic Society》2021,41(16):232-238
Ceramic microspheres have attracted significant attention, while the preparation of hierarchically porous ceramic microspheres with high porosity, good sphericity, and controllable size or shape in a short time remains a challenge. Herein, we developed a highly adaptable methodology for the preparation hierarchically porous ceramic microspheres with high porosity and favorable shape in a short time. The UV-curing assisted molding method combined with the Pickering emulsion method was utilized to prepare hierarchically porous ceramic microspheres. Under the irradiation of a UV-curing lamp (395 nm, 50 W), the Pickering emulsion can be cured within as short as 10 s. The microstructures of the three microspheres with different shapes were characterized by scanning electron microscopes (SEM). The as-prepared microspheres had a high sphericity, the interconnectivity of pores was as high as 54 %, and its porosity was as high as 73.4 % ± 3.0 %, while the density was quite low at ∼ 1.02 g/cm3. 相似文献
75.
76.
利用扫描电镜(SEM)、激光粒度分析仪(LDPSA)、X射线衍射仪(XRD)以及比表面积分析仪(SSA)等检测方法,研究了烧结对于羟基磷灰石微球的微观结构、形貌以及粒径、比表面积和孔隙率等性能的影响。结果表明,经800℃热处理,微球的比表面积、孔隙率及其表面形貌均会发生明显的变化;经1000℃烧结后,部分羟基磷灰石相发生热分解,生成较多的的 相似文献
77.
采用含乙烯基聚硅氮烷为原料,利用先驱体转化法与有机泡沫浸渍法相结合制备SiCN泡沫陶瓷。通过聚氨酯泡沫及聚硅氮烷的热分析制定温度曲线,研究了裂解温度、浸渍/裂解增强处理次数等工艺参数对泡沫陶瓷抗压强度的影响,采用XRD、SEM及EDS对SiCN泡沫陶瓷进行了物相、微观结构及成分分析。结果表明,在1000~1400℃温度范围内,随着温度的升高,泡沫陶瓷的抗压强度先升高后降低,增强处理对提高抗压强度有明显效果,当裂解温度为1300℃,经二次增强处理后,试样的抗压强度达11.5MPa。XRD研究表明,随着温度的逐步升高,聚硅氮烷的裂解产物发生了由非晶态向晶态的转变。微观结构分析显示,SiCN泡沫陶瓷呈三维网状结构,具有良好的贯通性,开孔气孔率达到85%。 相似文献
78.
Kasem K. Kasem Franklin A. Schultz 《Journal of Inorganic and Organometallic Polymers》1994,4(4):377-390
Multiply charged electroactive anions [IrCl
6
2–
, Fe(CN)
6
3–
, and W(CN)
8
4–
] are electrostatically incorporated in polymeric films of tris(4-vinyl-4-methyl-2,2-bipyridine) ruthenium(II) [poly-Ru(vbpy)
3
2+
] from aqueous trifluoroacetate solution. Values of apparent diffusion coefficients (D
ct) and heterogenous electron transfer rates (k
et) are measured for these anions as a function of their relative concentration (
M/
Ru) in the film.D
ct andk
et decrease systematically as
M/
Ru increases in a manner that is independent of charge and chemical identity of the ion. This result suggests that a nonchemical process, presumably electrostatic cross-linking, limits diffusional motion and is responsible for the decrease inD
ct andk
et with increasing anion content. Protonated polyvinyl-pyridine films exhibit similar ranges and variations inD
ct andk
et, which suggest similar structures and mechanisms of charge transport for these films and poly-Ru(vbpy)
3
2+
. 相似文献
79.
Junwei Xiang Chuanzhou Han Jianhang Qi Yanjie Cheng Kai Chen Yongming Ma Jiayu Xie Yue Hu Anyi Mei Yinhua Zhou Hongwei Han 《Advanced functional materials》2023,33(25):2300473
Due to the low cost and excellent potential for mass production, printable mesoscopic perovskite solar cells (p-MPSCs) have drawn a lot of attention among other device structures. However, the low open-circuit voltage (VOC) of such devices restricts their power conversion efficiency (PCE). This limitation is brought by the high defect density at perovskite grain boundaries in the mesoporous scaffold, which results in severe nonradiative recombination and is detrimental to the VOC. To improve the perovskite crystallization process, passivate the perovskite defects, and enhance the PCE, additive engineering is an effective way. Herein, a polymeric Lewis base polysuccinimide (PSI) is added to the perovskite precursor solution as an additive. It improves the perovskite crystallinity and its carbonyl groups strongly coordinate with Pb2+, which can effectively passivate defects. Additionally, compared with its monomer, succinimide (SI), PSI serves as a better defect passivator because the long-chained macromolecule can be firmly anchored on those defect sites and form a stronger interaction with perovskite grains. As a result, the champion device has a PCE of 18.84%, and the VOC rises from 973 to 1030 mV. This study offers a new strategy for fabricating efficient p-MPSCs. 相似文献
80.
Chung Yen Ang Si Yu Tan Cathleen Teh Jia Min Lee Mun Fei Eddy Wong Qiuyu Qu Li Qing Poh Menghuan Li Yuanyuan Zhang Vladimir Korzh Yanli Zhao 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(7)
Responsive nanomaterials have emerged as promising candidates as drug delivery vehicles in order to address biomedical diseases such as cancer. In this work, polymer‐based responsive nanoparticles prepared by a supramolecular approach are loaded with doxorubicin (DOX) for the cancer therapy. The nanoparticles contain disulfide bonds within the polymer network, allowing the release of the DOX payload in a reducing environment within the endoplasm of cancer cells. In addition, the loaded drug can also be released under acidic environment. In vitro anticancer studies using redox and pH dual responsive nanoparticles show excellent performance in inducing cell death and apoptosis. Zebrafish larvae treated with DOX‐loaded nanoparticles exhibit an improved viability as compared with the cases treated with free DOX by the end of a 3 d treatment. Confocal imaging is utilized to provide the daily assessment of tumor size on zebrafish larva models treated with DOX‐loaded nanoparticles, presenting sustainable reduction of tumor. This work demonstrates the development of functional nanoparticles with dual responsive properties for both in vitro and in vivo drug delivery in the cancer therapy. 相似文献