This paper describes the method of onion-like nanoparticles synthesis in a microflow. As the core of a material, platinum nanoparticles were used. The first shell consists of metallic palladium, and the second one is metallic gold, respectively. The synthesis of onion-like nanostructure was performed using microflow reactors system, which consists of 3 independent elements. As the reducing agent of precious metals ions, vitamin C was used. To prevent NPs from the aggregation, a polyvinyl alcohol as the stabilizing agent was applied.
Authors:J. L. Zeng, L. X. Sun, F. Xu, Z. C. Tan, Z. H. Zhang, J. Zhang, and T. Zhang
In this paper, organic phase change materials (PCM)/Ag nanoparticles composite materials were prepared and characterized for the first time. The effect of Ag nanoparticles on the thermal conductivity of PCM was investigated. 1-tetradecanol (TD) was selected as a PCM. A series of nano-Ag-TD composite materials in aqueous solution were in-situ synthesized and characterized by means of thermal conductivity evaluation method, TG-DSC, IR, XRD and TEM. The results showed that the thermal conductivity of the composite material was enhanced as the loading of Ag nanoparticles increased. The composite materials still had relatively large phase change enthalpy. Their phase change enthalpy could be correlated linearly with the loading of TD, but their phase change temperature was a little bite lower than that of pure TD. The thermal stability of the composite materials was close to that of pure TD. It appeared that there was no strong interaction between the Ag nanoparticles and the TD. Furthermore, the experiment results indicated that the Ag nanoparticles dispersed uniformly in the materials, occurred in the forms of pure metal.
Authors:Shailja Arora, Pratibha Kapoor, and Madan Singla
In this study, a high catalytic activity of palladium nanoparticles immobilized on alumina (Al2O3) is reported for the industrially important reduction of aromatic nitro compounds to amino compounds. The palladium nanoparticles
were immobilized on alumina by a simple physical precipitation method. The synthesis of palladium nanoparticles was done in
ethylene glycol without using any external stabilizing agent. The composite particles exhibited good colloidal stability.
The catalytic activity is investigated qualitatively by high performance liquid chromatography (HPLC) and quantitatively by
photometrically monitoring the reduction of p-nitrophenol by an excess of sodium borohydride (NaBH4) in the presence of nanocomposites. The kinetic data could be explained by the assumption of pseudo first-order reaction
with respect to p-nitrophenol.
Authors:M. Avella, S. Cosco, M. L. Di Lorenzo, E. Di Pace, and M. E. Errico
Summary The influence of calcium carbonate nanoparticles with different shapes (spherical and elongated) on the thermal properties and crystallization behavior of isotactic polypropylene was investigated. CaCO3 nanoparticles were covered by an appropriate coating agent to improve the interfacial adhesion between the filler and the polyolefin matrix. The nanocomposites were prepared by melt mixing and subsequent compression molding. A remarkable effect of CaCO3 on the thermal properties of iPP was observed. Moreover, the analysis of crystallization kinetics showed that CaCO3 nanopowder coated with PP-MA are efficient nucleating agents for iPP, and the overall crystallization rate results higher than plain iPP.
Authors:K. Katok, V. Tertykh, V. Yanishpolskii, A. Ragulya, V. Klimenko, and D. Klymchuk
Matrix isolation of ferroelectric BaTiO3 nanoparticles was executed by formation of protective silica shell (via hydrolysis and polycondensation of tetraethyl orthosilicate)
on particles of precursor—barium titanyl oxalate. Synthesized BaTiO3–SiO2 composites have been characterized by IR spectroscopy, XRD, TEM, DTA/DTG methods.
Authors:Swee Yap, Yuan Yuan, Lu Zheng, Wai Wong, Ning Yan, and Saif Khan
In this paper, we present detailed experimental and modeling studies of a recently developed triphasic segmented flow millireactors for rapid nanoparticle-catalyzed gas–liquid reactions. We first present detailed observations of the hydrodynamics and flow regimes in a pseudo-biphasic mode of operation, which enable the design and selection of optimal operating conditions for the triphasic millireactor. We particularly focus on and analyze the presence of wetting films of the organic phase on the reactor walls at high flow speeds, a consequence of the phenomenon of forced wetting, which is a key ingredient for optimal reactor performance. Next, we describe the development of a simple phenomenological model, incorporating the key mass transport steps that accurately captures the observed experimental trends for the rhodium nanoparticle (RhNP) catalyzed hydrogenation of a model substrate (1-hexene). We further discuss and analyze the consequences of this model.
Authors:R. Selvakumar, S. Aravindh, C. Kaushik, V. Katarani, Vidya Thorat, Prema Gireesan, V. Jayavignesh, K. Swaminathan, and Kanwar Raj
The present study involves the screening of silver nanoparticles containing carbonized yeast cells isolated from coconut cell
sap for efficient adsorption of few long lived radionuclides like 137Cs55, 60Co27, 106Ru44, 239Pu94 and 241Am95. Yeast cells containing silver nanoparticles produced through biological reduction were subjected to carbonization (400 °C
for 1 h) at atmospheric conditions and their properties were analyzed using fourier transform infra-red spectroscopy, X-ray
diffraction, scanning electron microscope attached with energy dispersive spectroscopy and transmission electron microscope.
The average size of the silver nanoparticles present on the surface of the carbonized silver containing yeast cells (CSY)
was 19 ± 9 nm. The carbonized control yeast cells without silver exposure (CCY) did not contain any particles on its surface.
The efficiency of CSY and CCY towards the radionuclide adsorption was studied in batch mode at fixed contact time, concentration,
and at its native pH. CSY was efficient in removal of 239Pu94 (76.75%) and 106Ru44 (54.73%) whereas CCY showed efficient removal only for 241Am95 (62.89%). Both the adsorbents did not show any retention with respect to 60Co27 and 137Cs55. Based on the experimental data, decontamination factor and distribution coefficient (Kd) were calculated and, from the values, it was observed that these adsorbents have greater potential to adsorb radionuclides.
Authors:S. Fatahian, D. Shahbazi-Gahrouei, M. Pouladian, M. Yousefi, Gh. Amiri, and A. Noori
DMSA-coated Fe3O4 nanoparticles were synthesized by wet-chemical method. The chemical interaction between Fe3O4 and DMSA were investigated by FTIR. They were directly radiolabeled with 99mTc radioisotope (Fe3O4@DMSA–99mTc) at room temperature in the presence of stannous solution as a reducing agent. Magnetic and structure properties of Fe3O4@DMSA–99mTc nanoparticles were investigated by AGFM, TEM, and XRD. Biodistribution and toxicity assessment of Fe3O4@DMSA–99mTc were studied in mice by intravenous and intraperitoneally injections, respectively. Blood, kidney, and liver factors were
measured 4 days post injection and at the mean-while tissue sections were prepared from their kidney and liver. The results
indicate that, the Fe3O4@DMSA–99mTc nanoparticles were passed through the membrane of different cells but do not create any disorder in the kidney and liver
function even in high doses such as 300 mg/kg.
Nanosized copper particles are widely used in fields of lubricants, polymers/plastic, metallic coating and ink. Recently,
we found that copper particles in different sizes can lead to different toxicological effects. To clarify the target organs
of copper particles of different sizes, the inductively coupled plasma mass spectroscopy (ICP-MS) was employed to evaluate
the distribution of copper in different organs of mice after a single dose oral exposure. The results suggest that the main
target organs for copper nanoparticles are kidney, liver and blood. Liver is the main damaged organ.
Carbon encapsulated Au@Fe nanoparticles (NPs) were synthesized by the hydrothermal method, and the palladium NPs (12 nm) were
immobilized on this hydroxyl-terminated support. The morphology, composition, content and magnetism of the samples were characterized.
Compared with the commercial carbon-supported Pd catalyst, high catalytic activity, recyclability and selectivity were evaluated
by the catalyst Pd/(C@(Au@Fe)) in the Heck reaction. Especially, in the Heck cross-coupling reactions of iodobenzene and methyl
acrylate, the catalyst was reused 10 times without significant loss of activity. In addition, the catalyst was simply recycled
by a magnetic field.