纳米四氧化三铁表面酸碱性质研究

制备了纳米Fe3O4, 并对其进行了表征和表面酸碱行为研究. 实验结果表明, Fe3O4表面在水溶液中有非常明显的酸碱性质. 随着纳米Fe3O4加入量的增多, 溶液pH缓冲能力增强, 二者之间成正比, 据此可定量地测定H+在纳米氧化铁表面的吸附量. 运用MEDUSA和WINSGW计算软件计算了表面组分在溶液中的分布， 并讨论了表面电荷对表面组分分布的影响.     

醇热解法合成超顺磁性氧化铁纳米粒子及其性能

以甲氧基聚乙二醇同时作为溶剂、还原剂及修饰剂,在高温下分解乙酰丙酮铁,制备了纳米Fe3O4粒子,采用透射电子显微镜和X射线衍射分析表征材料的形貌和相组成,傅里叶变换红外光谱仪表征材料的表面修饰物,超导量子干涉仪测试合成的纳米粒子的磁性能,纳米粒度与zeta电势分析仪测试磁性纳米粒子在水中的zeta电势。 结果表明,纳米Fe3O4粒子的大小为（10.1±1.6） nm,粒度均一,单分散性好,在300 K下具有超顺磁性,饱和磁化强度为45 A·m2/kg。 红外结果表明,-COO-共价结合在粒子表面。 zeta电势为-25 mV。 其在水中的稳定性与以三甘醇为反应介质、高温分解法制备的纳米Fe3O4粒子作比较,表现出长时间（60 d以上）的良好分散性。 静电作用及空间位阻效应是其高稳定分散性的原因。     

Physical and Chemical Properties of Magnetite and Magnetite-Polymer Nanoparticles and Their Colloidal Dispersions

The properties of polymer-coated magnetite nanoparticles, which have the potential to be used as effective magnetic resonance contrast agents, have been studied. The magnetite particles were synthesized by using continuous synthesis in an aqueous solution. The polymer-coated magnetite nanoparticles were synthesized by seed precipitation polymerization of methacrylic acid and hydroxyethyl methacrylate in the presence of the magnetite nanoparticles. The particle size was measured by laser light scattering. It was shown that the particle size, variance, magnetic properties, and stability of aqueous magnetite colloidal dispersion strictly depend on the nature of the stabilizing agent. The average hydrodynamic radius of the magnetite particles was found to be 5.7 nm in the stable aqueous colloidal dispersion. An inclusion of the magnetite particle into a hydrophilic polymeric shell increases the stability of the dispersion and decreases the influence of the stabilizing agent on the magnetic and structural properties of the magnetite particles as was shown by X-ray diffraction and M?ssbauer and IR spectroscopy, as well as by vibrating sample magnetometry. The variation in the polymeric shell size and the polymer net density can be useful tools for evaluation of the polymer-coated magnetite particles as effective contrast agents. Copyright 1999 Academic Press.     

聚电解质溶液中纳米粒子扩散系数的模耦合理论计算

采用模耦合理论(MCT)建立了研究纳米粒子在聚电解质溶液中长时扩散系数D的介观统计方法,提出了有效的聚合物溶液动态散射函数Γpp(k,t)的约化形式.定量计算了溶液微观密度涨落对扩散系数的贡献,考察了扩散系数D对溶液浓度c及纳米粒子半径R的依赖关系,并定量分析了MCT与经典StokesEinstein(S-E)关系的偏离.结果表明,MCT方法的研究结果与实验数据吻合.当纳米粒子尺寸小于聚电解质特征尺寸时,其扩散系数对S-E关系明显偏离.本文建立的基于微观描述的MCT方法为进一步研究纳米粒子在聚合物溶液中的含时扩散动力学行为奠定了理论基础.     

Cryochemical Synthesis of Magnetite Nanoparticles

Magnetite nanoparticles 2–20 nm in size, forming agglomerates up to 70 nm in size, are obtained by cryochemical synthesis.     

Effect of Magnetite Nanoparticles on the Dielectric Properties of Nanocomposites Based on Linear Low-Density Polyethylene

Russian Journal of Physical Chemistry A - The effect magnetite nanoparticles on the dielectric properties of nanocomposites based on linear low-density polyethylene in the 10−2–105 Hz...     

Reversible Diels–Alder Reactions with a Fluorescent Dye on the Surface of Magnetite Nanoparticles

Diels–Alder reactions on the surface of nanoparticles allow a thermoreversible functionalization of the nanosized building blocks. We report the synthesis of well-defined magnetite nanoparticles by thermal decomposition reaction and their functionalization with maleimide groups. Attachment of these dienophiles was realized by the synthesis of organophosphonate coupling agents and a partial ligand exchange of the original carboxylic acid groups. The functionalized iron oxide particles allow a covalent surface attachment of a furfuryl-functionalized rhodamine B dye by a Diels–Alder reaction at 60 °C. The resulting particles showed the typical fluorescence of rhodamine B. The dye can be cleaved off the particle surface by a retro-Diels–Alder reaction. The study showed that organic functions can be thermoreversibly attached onto inorganic nanoparticles.     

平面铂电极上吸附氢原子表面扩散系数的测定

This Paper describes an experimental method that established a local Pt/Nafion interface on the Platinum Plane, so that the boundary conditions and the initial condition of the (diffusion equation about the diffusion of adsorbed hydrogen atom the platinum plane can be controlled. The average diffusion coefficient of underpotential deposition of hydrogen on a surface of platinum was obained for the first time and D=1.50 ×10-4cm2•s-1.The accuracy of the datum was discussed.     

Surface Functionalization of Magnetite Nanoparticles with Multipotent Antioxidant as Potential Magnetic Nanoantioxidants and Antimicrobial Agents

Functionalized magnetite nanoparticles (Fe₃O₄) were prepared using the coprecipitation method followed by functionalization with a multipotent antioxidant (MPAO). The MPAO was synthesized and analyzed using FTIR and NMR techniques. In this study, the functionalized nanoparticles (IONP@AO) were produced and evaluated using the FTIR, XRD, Raman, HRTEM, FESEM, VSM, and EDX techniques. The average determined particle size of IONP@AO was 10 nanometers. In addition, it demonstrated superparamagnetic properties. The magnitude of saturation magnetization value attained was 45 emu g⁻¹. Virtual screenings of the MPAO’s potential bioactivities and safety profile were performed using PASS analysis and ADMET studies before the synthesis step. For the DPPH test, IONP@AO was found to have a four-fold greater ability to scavenge free radicals than unfunctional IONP. The antimicrobial properties of IONP@AO were also demonstrated against a variety of bacteria and fungi. The interaction of developed nanoantioxiants with biomolecules makes it a broad-spectrum candidate in biomedicine and nanomedicine.     

Anomalous Diffusion of Nanoparticles in Water Close to a Porous Surface

The diffusion coefficient of macromolecules in water depends on the distance to a rough surface by a fractional-power law, which shows that diffusion can be described using a fractal model.     

铁表面银纳米粒子自组装膜及其缓蚀性能研究

应用化学还原法于水溶液中制备银纳米粒子.在十二烷基硫醇的保护下,将银纳米粒子从水相转移到甲苯相,并将处理好的铁电极浸泡在含有十二烷基硫醇保护的银纳米粒子/甲苯溶液中,制得十二烷基硫醇/银纳米粒子自组装混合膜.电化学方法如交流阻抗谱（EIS）、极化曲线等研究该自组装膜在0.5 mol.L-1H2SO4溶液中的缓蚀作用.XPS测试证实该自组装膜十二烷基硫醇和银纳米粒子之存在.     

Time-dependent Diffusion Coefficient and Conventional Diffusion Constant of Nanoparticles in Polymer Melts by Mode-coupling Theory (cited: 2)

Time-dependent diffusion coefficient and conventional diffusion constant are calculated and analyzed to study diffusion of nanoparticles in polymer melts. A generalized Langevin equa-tion is adopted to describe the diffusion dynamics. Mode-coupling theory is employed to calculate the memory kernel of friction. For simplicity, only microscopic terms arising from binary collision and coupling to the solvent density fluctuation are included in the formalism. The equilibrium structural information functions of the polymer nanocomposites required by mode-coupling theory are calculated on the basis of polymer reference interaction site modelwith Percus-Yevick closure. The effect of nanoparticle size and that of the polymer size are clarified explicitly. The structural functions, the friction kernel, as well as the diffusion coefficient show a rich variety with varying nanoparticle radius and polymer chain length. We find that for small nanoparticles or short chain polymers, the characteristic short time non-Markov diffusion dynamics becomes more prominent, and the diffusion coefficient takes longer time to approach asymptotically the conventional diffusion constant. This constant due to the microscopic contributions will decrease with the increase of nanoparticle size, while increase with polymer size. Furthermore, our result of diffusion constant from mode-coupling theory is compared with the value predicted from the Stokes-Einstein relation. It shows that the microscopic contributions to the diffusion constant are dominant for small nanoparticles or long chain polymers. Inversely, when nanonparticle is big, or polymer chain is short, the hydrodynamic contribution might play a significant role.     

纳米四氧化三铁(Fe3O4)的制备和形貌

纳米Fe₃O₄因其特殊的理化性质和在生物医学领域潜在的应用价值而得到广泛研究。本文综述了纳米Fe3O4的制备方法，包括直流电弧等离子体法、热分解方法、沉淀法、水热法、电化学法、微乳液法、溶胶-凝胶法、有机物模板法、回流法等，结合作者在Fe3O4纳米粒子制备方面的最新工作，介绍了Fe3O4纳米粒子的新颖形貌。对纳米级Fe3O4制备研究的发展趋势进行了展望。     

Surface Functionalization of Magnetite Nanoparticles with Sulfonic Acid and Heteropoly Acid: Efficient Magnetically Recoverable Solid Acid Catalysts

New magnetically recoverable solid acid catalysts for acid‐catalyzed reactions were designed via the surface chemical functionalization of silica‐coated magnetite nanoparticles (SCMNPs) with sulfonic acid groups. First, the SCMNPs were covalently functionalized with 3‐aminopropyl groups to achieve Amp‐SCMNPs. Then, reaction of the Amp‐SCMNPs with 1,4‐butane sultone followed by acidification with phosphotungstic acid (HPW) or diluted sulfuric acid produced magnetically recoverable solid acid catalysts, HPW‐ampsul‐SCMNPs and H‐ampsul‐SCMNPs, respectively. Both catalysts were characterized by various physicochemical analyses such as Fourier transform infrared (FT‐IR) and inductively coupled plasma‐optical emission (ICP‐OES) spectroscopies, vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and energy‐dispersive X‐ray (EDX) analyses. Finally, the catalytic activities of the prepared catalysts were examined in the esterification of acetic acid with butanol and acetalization of benzaldehyde with ethylene glycol. Excellent catalytic efficiencies were obtained in both cases. The catalysts were consecutively recovered and reused five times without significant loss of their activities.     

SDS/BA/H2O体系的扩散系数与结构特性

在无探针条件下，用电化学方法测定了ＳＤＳ／ＢＡ／Ｈ２Ｏ三组分体系的扩散系数和扩散活化能。结果表明，Ｌ１区域由Ｏ／Ｗ结构微乳液与油、水双连续结构微乳液两个小区域组成，并不是单一的Ｏ／Ｗ区域。在Ｏ／Ｗ区域内，微乳液以液滴状态存在，具有较好的扩莠性能和较小的扩散活化能；在ＢＩ区域，水与ＢＡ同作为连续相与被增溶相存在，缔合体系呈网络结构，扩散性能较低，扩莠活化能较大。     

Micellar Thin-Layer Chromatography and Preconcentration of L-Carnitine with Magnetite Nanoparticles

Journal of Analytical Chemistry - Thin-layer chromatography (TLC) is used to study the chromatographic behavior of L-carnitine in aqueous–organic mobile phases (MPs) and aqueous MPs in the...     

稀土对渗碳过程碳扩散系数和传递系数的影响

通过对20钢常规气体渗碳和稀土渗碳层深的测定，计算出稀土渗碳时碳在奥氏体中的平均扩散系数。从渗碳增重动力学出发，推导出渗碳过程混合控制阶段界面传递系数的计算公式。稀土元素加速渗碳过程的主要原因是增加了碳在奥氏体中的扩散系数，同时提高了碳的界面传递系数。     

电解质对吸附于纳米银粒子表面荧光素的光谱学性质的影响

在含有纳米银的荧光素溶液(Fl-Ag)中引入KNO₃、KCl、Ca(NO₃)₂和CaCl₂电解质,利用透射电子显微镜、紫外-可见分光光度计和荧光分光光度计等技术研究电解质对Fl-Ag溶液的显微结构和光谱学性质的影响。结果表明,电解质离子与纳米银粒子间存在较强的相互作用,这种强的相互作用造成纳米银粒子不同程度的聚集和生长。各电解质引起的纳米银粒子的聚集程度关系为CaCl₂＞Ca(NO₃)₂＞KCl＞KNO₃。随着电解质加入量的增加,溶液的荧光强度先下降,而后又逐渐增强,直至达到定值。各电解质对Fl-Ag溶液的荧光强度影响强弱关系为Ca(NO₃)₂＞CaCl₂＞KCl＞KNO₃。本文从分子间的相互作用、能量传输等方面探讨了电解质离子对含有纳米银的荧光素溶液的显微结构和光学性能影响机理。