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221.
Zei-Tsan Tsai Jen-Fei Wang Hsiao-Yun Kuo Chia-Rui Shen Jiun-Jie Wang Tzu-Chen Yen 《Journal of magnetism and magnetic materials》2010,322(2):208-213
Iron oxide nanocrystals are of considerable interest in nanoscience and nanotechnology because of their nanoscale dimensions, nontoxic nature, and superior magnetic properties. Colloidal solutions of magnetic nanoparticles (ferrofluids) with a high magnetite content are highly desirable for most molecular imaging applications. In this paper, we present a method for in situ coating of superparamagnetic iron oxide (SPIO) with chitosan in order to increase the content of magnetite. Iron chloride salts (Fe3+ and Fe2+) were directly coprecipitated inside a porous matrix of chitosan by Co-60 γ-ray irradiation in an aqueous solution of acetic acid. Following sonication, iron oxide nanoparticles were formed inside the chitosan matrix at a pH value of 9.5 and a temperature of 50 °C. The [Fe3+]:[Fe2+]:[NH4OH] molar ratio was 1.6:1:15.8. The final ferrofluid was formed with a pH adjustment to approximately 2.0/3.0, alongside with the addition of mannitol and lactic acid. We subsequently characterized the particle size, the zeta potential, the iron concentration, the magnetic contrast, and the cellular uptake of our ferrofluid. Results showed a z-average diameter of 87.2 nm, a polydispersity index (PDI) of 0.251, a zeta potential of 47.9 mV, and an iron concentration of 10.4 mg Fe/mL. The MRI parameters included an R1 value of 22.0 mM−1 s−1, an R2 value of 202.6 mM−1 s−1, and a R2/R1 ratio of 9.2. An uptake of the ferrofluid by mouse macrophages was observed. Altogether, our data show that Co-60 γ-ray radiation on solid chitosan may improve chitosan coating of iron oxide nanoparticles and tackle its aqueous solubility at pH 7. Additionally, our methodology allowed to obtain a ferrofluid with a higher content of magnetite and a fairly unimodal distribution of monodisperse clusters. Finally, MRI and cell experiments demonstrated the potential usefulness of this product as a potential MRI contrast agent that might be used for cell tracking. 相似文献
222.
岩心表面润湿性与化学选堵剂对油水的封堵能力 总被引:1,自引:0,他引:1
选择阳离子聚丙烯酰胺类选堵剂,进行岩心模拟实验,研究不同岩心表面润湿性与化学选堵剂封堵能力之间的关系.表面润湿性强烈影响对水的堵塞率,水润湿性越强,对水的堵塞率越高,典型的亲水表面和亲油表面对水的堵塞率相差20%左右;使用水基凝胶,水驱后的残余阻力系数(RRF)大于油驱后的RRF,水基凝胶使水相渗透率的降低比油相渗透率的降低多.对于润湿性相同,渗透率不同的天然岩心,选堵剂的堵水率大于85%,堵油率在20%左右,表现出良好的选择性. 相似文献
223.
荧光素主要用于生物细胞染色。本文合成了二氯荧光素二丙烯酸酯,并用元素分析,核磁共振,红外、紫外、荧光光谱进行表征,考察发现它对人体外培养肿瘤细胞L1210有很强的瞬时杀伤作用;对人体胃腺癌(SGC 7901)细胞增殖有很强的抑制作用;并可用于鉴定蚕豆花粉细胞的生活力和生活状态。1 实验部分1 1 试剂与仪器荧光素(上海医药化工试剂采购供应站)、丙烯酸、氯化亚砜(A R)。细胞由中科院上海药物研究所提供。意大利1106型元素分析仪,NICOLETFT IR170SX型IR仪(KBr压片),FT Ac80型核磁共振仪,KOFLER熔点仪(温度计未校正)。1 2 … 相似文献
224.
Numerous polycondensations of aliphatic diol of isosorbide and 1,8-dimesyloctane or other aliphatic dibromo and disulphonated alkylating agent was performed under phase-transfer catalytic conditions. In order to check the possible specific non-thermal microwave (MW) effects, reactions were comparatively performed inside a thermostated oil bath (Δ) under similar conditions. The reactions conditions were varied to optimize both, the fraction insoluble in methanol (FP MeOH) and the molecular weight of polyethers. In all cases, it was found that microwave-assisted polycondensations proceeded more efficiently compared with conventional heating (the reaction time was reduced from 24 h to 30 min: ratio 1/50). The polycondensation under microwave yields 63% of polyethers precipitating in methanol with relatively high average-weight molecular weights (Mw up to approximately 7000). The polyethers were characterized by NMR (1H, 13C) and FT-IR spectroscopy and SEC measurement and MALDI-TOF mass spectrometry. 相似文献
225.
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227.
一个基于Multi-agent的决策支持系统的设计 总被引:6,自引:0,他引:6
在DSS开发中,引入agent技术,提出了一个基于Multi-agent的决策支持系统的框架结构设计并为该系统的造界面Aent、信息Agent,模型Agent和管理Agent,在实际使用中,取得了良好的效果。 相似文献
228.
采用正电子漂没寿命谱(PALS)研究固化剂的种类有含量对环氧树脂基体自由体积特性、力学性能和密度的影响,实验结果表现:固化剂的含量与理论值接近,固化产物的自由体积半径越小,密度越高,力学性能越好,固化剂中的氨基对环氧基发生交联作用的程度,直接影响了固化产物的密度及力学性能。 相似文献
229.
镱的原子吸收分析进展 总被引:1,自引:0,他引:1
米瑞华 《光谱学与光谱分析》1992,12(2):105-110
本文对近些年来用电热原子吸收和火焰原子吸收测定镱时,为提高镱的灵敏度而采用的各种方法进行总结评述。 相似文献
230.
MRI contrast-dose relationship of manganese(III)tetra(4-sulfonatophenyl) porphyrin with human xenograft tumors in nude mice at 2.0 T 总被引:1,自引:0,他引:1
David A. Place Patrick J. Faustino Kirsten K. Berghmans Peter C.M. van Zijl A.Scott Chesnick Jack S. Cohen 《Magnetic resonance imaging》1992,10(6):919-928
Previously we reported that Mn(III)tetra(4-sulfonatophenyl) porphyrin, MnTPPS4, is a contrast agent which can effectively enhance tumor detection by MRI. By imaging 30 additional athymic nude mice bearing subcutaneous MCF-7 WT human breast carcinoma xenografts, we have extended dose-contrast relationships over a wide range of intraperitoneal (IP) doses ranging from 0.025 to 0.50 mmol/kg. The benefits of IP injection are higher possible doses on a volume basis and a reduction in toxicity versus IV administration. Full coronal cross-section images have been obtained on a 2-T spectrometer. Although individual tumor masses displayed different distribution patterns, reflective of their internal morphology, single doses of 0.10 mmol/kg or greater were necessary to produce a detectable effect. At a dose of 0.50 mmol/kg, marked enhancement was produced. Multiple small dosages administered over the course of several days before imaging did not produce increased enhancement. Preliminary results on the new porphyrin derivative, MnTPPS3, indicate that the ratio of the toxic dose to the effective dose may be adjustable to render this class of agents clinically useful. 相似文献