Leaf extract of medicinally important plant Ocimum sanctum (O. sanctum) has been used for the synthesis of nickel nanoparticles (NiGs) and extraction of quercetin (Qu). Qu has been conjugated with NiGs for enhanced anticancer effect on human breast cancer MCF-7 cells. Extracted Qu was conjugated with polyethylene glycol (PEG) coated NiGs (Qu-PEG-NiGs) which was used as carriers for breast cancer treatment. Anticancer activity of Qu-PEG-NiGs was evaluated by assessing cell viability, reactive oxygen species (ROS) production, caspase activity, mitochondrial membrane potential (MMP) and changes in nuclear morphology (staining methods). 0.85 mg of quercetin was extracted from 1 g of leaves with retention time (Rt) of 2.914 min. Loading and encapsulation efficiency of quercetin onto PEG-NiGs was 15.04% and 82% respectively and Qu-PEG-NiGs has shown a sustained release of Qu of about 84% after 48 h. Qu and Qu-PEG-NiGs showed dose dependent (1.56-50 μg/mL) anticancer effect against MCF-7 cells with IC50 values of 50 and 6.25 μg/mL respectively which was mediated by oxidative stress due to ROS over-production that induced loss of mitochondrial membrane potential, capsase -9, -7 activities leading to apoptosis. The present study validates that Qu-PEG-NiGs can be used as a potential anticancer agent for cancer therapy.
The microwave absorbents of Fe and C nanoparticles as magnetic loss and dielectric loss material respectively were composited with the polyvinyl alcohol (PVA) as binder by spray granulation method. The electromagnetic parameters of Fe and C composite particles were analyzed by vector network. The complex permittivity and magnetic permeability of Fe and C composite particles matched well with increasing C nanoparticle content, and then the microwave loss property was improved. A minimum reflection loss (RL) of -42.7 dB at 3.68 GHz for a composite with 4.6 mm in thickness can be obtained when the content ratio of the C nanoparticles, the modified Fe nanoparticles and the PVA is 21:49:30 (Sample 3).
In this communication, we report the results of the studies on electrical properties of Zn0.95Cr0.05O nanoparticles synthesized using sol-gel method. X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements were performed for the structural and microstructural behaviors of the nanoparticles. Rietveld analysis was carried out to confirm the single phasic nature. High resolution TEM (HRTEM) confirms the nanoscale nature and polycrystalline orientations in the samples. Dielectric response has been understood in the context of universal dielectric response (UDR) model along with the Koop’s theory and Maxwell - Wagner (M-W) mechanism. Variation in ac conductivity with frequency has been discussed in detail in terms of power law fits. Results of the impedance measurements have been explained on the basis of crystal cores and crystal boundary density. Cole - cole behavior has been studied for the impedance data. For potential application of nanoparticles, average normalized change (ANC) in impedance has been estimated and discussed in the light of size effects and oxygen vacancies.
Grain boundary (GB) segregation in nanocrystalline alloys can cause reduction of GB energy, which leads to thermodynamic stabilization of nanostructures. This effect has been modelled intensively. However, the previous modelling works were limited to substitutional alloy systems. In this work, thermodynamics of nanocrystalline binary interstitial alloy systems was modelled based on a two-sublattice model proposed by Hillert [M. Hillert, et al. Acta Chem. Scand., 24 (1970) 3618] and an atomic configuration for nanocrystalline systems proposed by Trelewicz and Schuh [J.R. Trelewicz, et al. Physical Review B, 79 (2009) 094112]. The modelling calculations agree with the reported experimental data, indicating that the current thermodynamic model is capable of accounting for the alloying effect in the nanocrystalline binary interstitial alloys.
Second-phase particle pinning has been well known as a mechanism impeding grain boundary (GB) migration, and thus, is documented as an efficient approach for stabilizing nanocrystalline (NC) materials at elevated temperatures. The pinning force exerted by interaction between small dispersed particles and GBs strongly depends on size and volume fraction of the particles. Since metallic oxides, e.g. Al2O3, exhibit great structural stability and high resistance against coarsening at high temperatures, they are expected as effective stabilizers for NC materials. In this work, NC composites consisting of NC Fe and Al2O3 nanoparticles with different amounts and sizes were prepared by high energy ball milling and annealed at various temperatures (Tann) for different time periods (tann). Microstructures of the ball milled and annealed samples were examined by X-ray diffraction and transmission electron microscopy. The results show that the addition of Al2O3 nanoparticles not only enhances the thermal stability of NC Fe grains but also reduces their coarsening rate at elevated temperatures, and reducing the particle size and/or increasing its amount enhance the stabilizing effect of the Al2O3 particles on the NC Fe grains.
A bulk nanostructured twinning-induced plasticity (TWIP) steel with high ductility and high strength was fabricated by cryogenic asymmetry-rolling (cryo-ASR) and subsequent recovery treatment. It was found that the cryo-ASRed TWIP steels exhibit simultaneous improvements in the ductility, strength and work hardening. Typical microstructures of the cryo-ASR TWIP steel were characterized by shear bands and intensive mechanical nano-sized twins induced by cryogenic deformation. These mechanical nano-scale twins remain thermally stable during the subsequent recovery treatment. It is believed that the ductility enhancement and high work-hardening ability for the cryo-ASR TWIP steels should be mainly attributed to the high-density pre-existing nano-scale twins.
High saturation magnetization (>90 emu/g) multi-walled carbon nanotubes (MWCNTs) and Fe4N nanoparticles composite were successfully synthesized by gas nitriding at 550 °C. Almost all Fe4N nanoparticles were evenly distributed inside the carbon nanotubes and formed a special composite microstructure. This composite microstructure shows excellent soft magnetic property, structural stability, and chemical stability at room temperature. The investigations of electromagnetic and microwave absorption performances indicate that microwave absorbing capacity of low frequency band of MWCNTs were greatly improved by addition of Fe4N nanoparticles.
MnFe2O4 nanoparticles were synthesized by thermal decomposition of a metal-organic salt in organic solvent with a high boiling point. Some nanoparticles exhibited the triangular shape which has not been observed before as far as we know, while some nanoparticles formed the aggregates with different sizes and shapes. The strength of interparticle dipolar interaction was changed by diluting MnFe2O4 nanoparticles in the SiO2 matrix with different concentrations. The strong dipolar interaction has been suggested to enhance the blocking temperature (TB) and suppress the remanence (Mr) to saturation (Ms) magnetization ratio (Mr/Ms) for the spherical-like cobalt ferrite nanoparticles in many previous reports. However, Mr/Ms and TB of MnFe2O4 nanoparticles reported herein mainly depend on the size and shape of the nanoparticles and their aggregates.
Shuriken-like nickel nanoparticles were successfully synthesized by a thermal decomposition method at 200 °C with Nickel(II) acetylacetonate (Ni(acac)2) as the precursor and oleylamine (OAm) as the solvent and reductant, respectively. The phase structures, morphologies and sizes, and magnetic properties of the as-synthesized nickel products were characterized in detail by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). Some key reaction parameters, such as the reaction time, reaction temperature and surfactants, have important influence on the morphology of the final products. XRD pattern indicated that the products are well-crystallized face-centered cubic (fcc) nickel phase. SEM images demonstrated that the nickel nanoparticles are shuriken-like morphology with average size around 150 nm. The mechanism of shuriken-like Ni nanoparticles (NPs) is proposed. The magnetic hysteresis loops of shuriken-like and spherical nickel products illustrated the ferromagnetic nature at 300 K, indicating its potential applications in magnetic storage.
Palladium nanoparticles were deposited on the amine-grafted glass fiber mat (GFM-NH2) catalyst support by a conventional impregnation process followed by the borohydride reduction in aqueous solution at room temperature to create the designed Pd/GFM-NH2 catalyst. By the use of large size glass fiber mat without nano/mesopores as the catalyst support, the internal mass transfer limitations due to the existence of nano/mesopores on the catalyst support were eliminated and the Pd/GFM-NH2 catalyst could be easily separated from treated water due to the large size of the catalyst support. Batch experiments demonstrate its good catalytic reduction performance of Cr(VI) with formic acid as the reducing agent. It also demonstrated an efficient Cr(VI) removal and stability in a lab-prepared, packed fixed-bed tube reactor for the continuous treatment of Cr(VI)-containing water. Thus, it has a good potential for the catalytic reduction of Cr(VI) in the water treatment practice.