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应用Fe~(3+)在裸云母表面制作DNA分子的AFM样品的方法 总被引:1,自引:0,他引:1
原子力显微镜(AFM)既是观测生物大分子的有力工具,也是生物单分子操纵的有力工具.脱氧核糖核酸分子(DNA)是记栽了生物信息的重要生命分子,同时也是在分子器件领域具有极大潜力的天然纳米材料.利用AFM对DNA分子观察和操纵时,制样是关键.云母具有原子级平整的表面可作为观测DNA分子时的基底,但由于其表面负电性而不能和DNA分子很好地结合,所以通常需要对云母进行表面修饰.本文给出一种通过加入适量三价铁离子溶液在裸云母表面制作DNA样品的方法,可取代传统的云母表面修饰.该制样方法既可应用到基于AFM技术的DNA分子的形貌观察,也可应用在基于AFM技术的对DNA的单分子操纵. 相似文献
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采用磁控溅射工艺在石英、云母与Ti/Si衬底上制备100 nm厚Cu膜,并在300℃条件下进行原位退火.用原子力显微镜(AFM)观察薄膜表面形貌,基于粗糙度方法与分形理论对其量化表征.结果表明:分形维数Di比粗糙度Rrms更能准确地表征薄膜表面几何形态;石英衬底上Cu膜具有较为复杂的表面结构,其Df值大于沉积在云母和Ti/Si衬底上薄膜的;经过退火处理后,所有薄膜的表面形貌均趋于平滑化,Df值减小. 相似文献
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利用微波-电子回旋共振等离子(ECR)增强型PVD设备,低温外延生长了SiGe(C)薄膜。对所制备样品的结晶性、表面形貌和成分与衬底温度、衬底偏置电压的关系进行了讨论,采用反射式高能电子衍射仪(RHEED)、原子力显微镜(AFM)和X射线衍射仪(XRD)对薄膜的晶体质量和表面形貌进行了分析。结果表明,用单靶制备Si(C)薄膜,在衬底温度为450℃时会得到质量较好的单晶薄膜。而利用双靶制备SiGe(C)薄膜,衬底温度为400℃、衬底偏置电压-15 V时会制备出更好的单晶薄膜。在衬底温度为400℃条件下,添加电流导入端子,在原有设备和衬底温度不变的条件下,当电流导入端子电压为-15 V时,制备的SiGe(C)单晶薄膜材料的AFM均方根粗糙度(Rrms)由原来的0.52 nm降低到0.41 nm。 相似文献
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从Au纳米粒子出发,利用竖直浸渍提拉法(dip-coating)成功将Au纳米粒子负载于基底(云母片/单晶硅片),并以3-氨丙基三甲氧基硅烷(APTMS)对单晶硅片进行改性,得到具有密度分布不同的Au纳米粒子two dimensional(2D)组装结构,制备方法简单易行。利用原子力显微镜(AFM)表征了不同制备条件下Au纳米粒子在基底表面的分布状态,结果表明,Au纳米粒子溶胶和偶联剂APTMS的浓度以及浸渍时间对Au纳米粒子在单晶硅片表面的密度分布起到决定性作用。 相似文献
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本文通过LB膜仪表面压力-面积(π-A)曲线测量和原子力显微镜(AFM)观测,研究了磷脂酰胆碱(PC)与硬脂酸(SA)二元混合系统在空气/水界面上的物理特性和形态学特征。π-A曲线分析表明,当温度保持在30℃,SA的摩尔分数(XSA)不变时,随着表面压力(π)的增加,二元混合系统的面积(A)不断减小;当表面压力(π)不变时,随着SA的摩尔分数(XSA)的增大,二元混合系统的面积(A)出现非线性周期性减小;表明二元系统从液态扩张相向液态有序相转变。通过吉布斯能量分析,从理论上给出了该系统凝聚程度随π和XSA变化的特征,原子力显微镜观测给出了凝聚程度变化的直观证据,对进一步了解生物膜液晶态的变化具有重要的生物学意义。 相似文献
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Changwoo Doe Sung‐Min Choi Steven R. Kline Hyung‐Sik Jang Tae‐Hwan Kim 《Advanced functional materials》2008,18(18):2685-2691
A new dispersant for stabilization of single wall carbon nanotubes (SWNTs) in water that simultaneously utilizes three different dispersion or stabilization mechanisms: surfactant adsorption, polymeric wrapping, and Coulomb repulsive interaction, has been demonstrated. The new dispersant, a charged rod‐like nanoparticle (cROD), is a cylindrical micelle wrapped by negatively charged polymers which is fabricated by the aqueous free radical polymerization of a polymerizable cationic surfactant, cetyltrimethylammonium 4‐vinylbenzoate (CTVB), in the presence of sodium 4‐styrenesulfonate (NaSS). The surface charge density of the cRODs is controlled by varying the concentration of NaSS. Dispersions of SWNTs are obtained by sonicating a mixture of SWNTs and cROD in water, followed by ultra‐centrifugation and decanting. While the cRODs with neutral or low surface change densities (0 and 5 mol % NaSS) result in very low dispersion power and poor stability, the cRODs with high surface charge densities (15, 25, and 40 mol % NaSS) produce excellent dispersions with SWNT concentration as high as 437 mg L?1 and long term stability. The sharp van Hove transition peaks of the cROD assisted SWNT dispersions indicate the presence of individually isolated SWNTs. Atomic force microscopy and small angle neutron scattering analysis show that the dominant encapsulation structure of the cROD assisted SWNTs is surfactant assisted polymeric wrapping. SWNTs dispersed by the cRODs can be fully dried and easily re‐dispersed in water, providing enhanced processibility of SWNTs. 相似文献
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以二水合氯化钯为原料,PVP(聚乙烯吡咯烷酮)为分散剂,抗坏血酸(从)为还原剂,在常温下还原Pd^2+制备纳米钯。通过激光动态散射法(DSL),透射电子显微镜(TEM)和X射线衍射仪(XRD)对纳米钯进行了表征分析,结果显示,在PVP分散剂的作用下,得到的纳米钯为粒径8nm~22nm,无其他的氧化物存在。该纳米钯材料可作为化学沉铜的活化液,可以减少沉铜的工艺步骤,经过金相显微镜观测化学镀铜后的孔背光级数均达到10级,通过扫描电镜观察镀铜层表面颗粒均匀、平整。所制备的纳米钯是一种优异的化学镀铜活化剂。 相似文献
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We report a new approach of reactive spinning to fabricate thermosetting cyanate ester micro‐scale diameter fibers with aligned single walled carbon nanotubes (SWNTs). The composite fibers were produced by first dispersing the SWNTs (1 wt %) in cyanate ester (CE) via solvent blending, followed by pre‐polymerization, spinning and then multiple‐stage curing. The pre‐polymerization, spinning and post‐spinning cure temperatures were carefully controlled to achieve good spun crosslinked fibers. Both pristine and amino‐functionalized SWNTs were used for the reinforced fiber spinning. Amino‐functionalized SWNTs (f‐SWNTs) were prepared by reacting acid‐treated SWNTs with toluene 2,4‐diisocyanate and then ethylenediamine (EDA). FTIR, optical microscopy and scanning electron microscopy (SEM) showed that the amino‐functionalized SWNTs were covalently and uniformly dispersed into the cyanate ester matrix and aligned along the fiber axis. The alignment was further confirmed using polarized Raman spectroscopy. The composite fibers with aligned amino‐functionalized SWNTs possess improved tensile properties with respect to neat CE fibers, showing 85, 140, and 420% increase in tensile strength, elongation and stress‐strain curve area (i.e., toughness), respectively. NH2‐functionalization of SWNTs improves their dispersibility, alignment and interfacial strength and hence tensile properties of composite spun fibers. Fiber spinning to align SWNTs using thermosetting resin is novel. Others have reported fiber spinning to align SWNTs in thermoplastics. However, thermosetting CE resins offer the advantages of low and controllable viscosity during spinning and reactivity with amino functional groups to enable f‐SWNT/CE covalent bonding. 相似文献