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排序方式: 共有210条查询结果,搜索用时 18 毫秒
41.
Synthesis of metal nanoparticles with specific properties is a newly established research area attracting a great deal of
attention. Several methods have been put forward for synthesis of these materials, namely chemical vapor condensation, arc
discharge, hydrogen plasma—metal reaction, and laser pyrolysis in the vapor phase, microemulsion, hydrothermal, sol-gel, sonochemical,
and microbial processes taking place in the liquid phase, and ball milling carried out in the solid phase.
The properties of metal nanoparticles depend largely on their synthesis procedures. In this paper the fundamentals, advantages,
and disadvantages of each synthesis method are discussed. 相似文献
42.
Darryl N. Williams Katie A. Gold Tracey R. Pulliam Holoman Sheryl H. Ehrman Otto C. Wilson Jr. 《Journal of nanoparticle research》2006,8(5):749-753
Magnetite nanoparticles were synthesized and functionalized by coating the particle surfaces with gum arabic (GA) to improve particle stability in aqueous suspensions (i.e. biological media). Particle characterization was performed using transmission electron microscopy (TEM) and dynamic light scattering (DLS) to analyze the morphology and quantify the size distribution of the nanoparticles, respectively. The results from DLS indicated that the GA-treated nanoparticles formed smaller agglomerates as compared to the untreated samples over a 30-h time frame. Thermogravimetric analyses indicated an average weight loss of 23%, showing that GA has a strong affinity toward the iron oxide surface. GA most likely contributes to␣colloid stability via steric stabilization. It was determined that the adsorption of GA onto magnetite exhibits Langmuir behavior. 相似文献
43.
Vishal Kandathil Manjunatha Kempasiddaiah Sanna Kotrappanavar Nataraj Sasidhar Balappa Somappa Siddappa A. Patil 《应用有机金属化学》2020,34(3):e5357
The utilization of deoxyribonucleic acid (DNA) in nanotechnology is a promising area of research wherein the distinct properties of DNA are exploited for the design and development of new materials and applications. The biodegradability and natural profusion of DNA makes it highly suitable for use in various fields. In this report, we have treated DNA as a bioligand, supported on functionalized magnetite for the grafting of palladium (Pd) nanoparticles to make Pd-DNA bio-nanocatalyst. The Pd-DNA was subjected to Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Brunauer–Emmett–Teller, energy dispersive X-ray spectroscopy, vibrating sample magnetometry, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectrometry analysis. The prepared Pd-DNA was found to be highly efficient in catalyzing Suzuki–Miyaura cross-coupling reaction with excellent yields when compared with commercially available palladium-based catalysts. Also, the Pd-DNA could be easily recovered from the reaction mass using an external magnet and recycled up to six times without substantial loss of activity. Furthermore, Felbinac, a non-inflammatory drug, was synthesized in quantitative yields using the Pd-DNA bio-nanocatalyst. 相似文献
44.
Altafhusen Naikwade Megha Jagadale Dolly Kale Shivanand Gajare Prakash Bansode Gajanan Rashinkar 《应用有机金属化学》2019,33(9)
Nano‐magnetite supported N‐heterocyclic carbene‐copper complex with wingtip ferrocene has been prepared via multi‐step procedure. The complex has been characterized by various analytical techniques such as fourier transform infrared (FT‐IR), fourier transform Raman (FT‐Raman), X‐ray photoelectron spectroscopy (XPS), X‐ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) analysis. The catalytic activity of the complex has been exploited in intramolecular O‐arylation of o‐iodoanilides under heterogeneous conditions. The complex could be successfully recycled up to twelve consecutive cycles. 相似文献
45.
Magnetite is the oldest magnet and the first material where the concept of a strong correlations driven metal–insulator transition was suggested and found at TV = 124 K in the so-called Verwey phase transformation. Recently, the structure below TV was solved revealing subtle electronic structure in the form of trimeron lattice that, according to yet another recent communication, may be switched within femtosecond range. In this review article, we argue that the same change of trimeron lattice can be achieved by a magnetic field, in the phenomenon called the easy axis switching. The results of many of our experiments show that although this process is best viewed by magnetization studies, it is also reflected in magnetostriction, causes some changes in electronic transport and can be observed microscopically by NMR that proved electronic order alteration. All those facts suggest that the axis switching process observed and studied by us is intimately linked with the fast change of electronic trimeron order mentioned above. 相似文献
46.
Ana Lucía Campaa Amaimen Guilln Ricardo Rivas Veronica Akle Juan C. Cruz Johann F. Osma 《Molecules (Basel, Switzerland)》2021,26(14)
This study presents the feasibility of using various functionalized substrates, Fe3O4 nanoparticles (NPs) and Al2O3 spheres, for the removal of Cd from aqueous solution. To improve the materials’ affinity to Cd, we explored four different surface modifications, namely (3-Aminopropyl) triethoxysilane (APTES), L-Cysteine (Cys) and 3-(triethoxysilyl) propylsuccinic anhydride (CAS). Particles were characterized by FTIR, FIB-SEM and DLS and studied for their ability to remove metal ions. Modified NPs with APTES proved to be effective for Cd removal with efficiencies of up to 94%, and retention ratios up to 0.49 mg of Cd per g of NPs. Batch adsorption experiments investigated the influence of pH, contact time, and adsorbent dose on Cd adsorption. Additionally, the recyclability of the adsorbent and its potential phytotoxicity and animal toxicity effects were explored. The Langmuir, Freundlich, pseudo-first-order and pseudo-second-order models were applied to describe the behavior of the Cd adsorption processes. The adsorption and desorption results showed that Fe3O4 NPs modified with APTES are promising low-cost platforms with low phytotoxicity for highly efficient heavy metal removal in wastewater. 相似文献
47.
Martin Bremholm Dr. Marcella Felicissimo Dr. Bo B. Iversen Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(26):4788-4791
A general solution : In situ synchrotron X‐ray scattering in a high‐pressure pulsed injection reactor (see picture) shows that magnetite nucleation and growth are temporally separated. Gram‐scale crystalline, pure phase, superparamagnetic magnetite nanoparticles were synthesized without surfactants in supercritical water in less than one hour using a laboratory‐scale continuous‐flow reactor.
48.
Synthesis of magnetite nanoparticles by precipitation with forced mixing is presented. Using this method it is easy to obtain a high product saturation degree and the constant pH value of the reaction system. The TEM and XRD measurments show that the average size of the product magnetite particles is less than 6.0-nm in the condition of [Fe2+]/[Fe3+]=0.5. The magnetic properties of the samples are discussed. 相似文献
49.
氧缺位的磁铁矿型化合物转化CO2成C的研究 总被引:5,自引:0,他引:5
在高温 (92 3K)下分解 Fe C2 O4制备了阳离子缺位的磁铁矿 (Fe3 O4 δ,0≤δ<1 ) ,并用 H2 还原使它变为氧缺位的磁铁矿 (Fe3 O4-δ,0 <δ<1 )。在 62 3K下研究了氧缺位磁铁矿对 CO2 分解成 C的反应性能 ,发现 CO2 几乎 1 0 0 %地转化成 C,CO2 中的氧以 O2 -形式被磁铁矿的氧缺位捕获 ,变成化学计量的 Fe3 O4。 XRD、M ssbauer谱及热失重和化学分析表明 ,H2 还原磁铁矿的时间愈长 ,缺氧程度愈大 ,分解 CO2 的活性愈高 ,Fe3 O4-δ、FeδO(0 <δ<1 )和 α- Fe是 CO2 分解的活性相。 相似文献
50.