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As one of the most well-known metal nanoparticles, gold nanoparticles (AuNPs) have attracted much attention for the biological applications. This great interest in AuNPs can be attributed to their outstanding physical and chemical properties, such as special optical and electrochemical characteristics, high X-ray attenuation ability, strong X-ray absorption, photothermal effect, stability and biocompatibility. In addition, due to the ease of synthesis and modification of the surface of AuNPs, it is possible to control their shape, size and surface characteristics. All these features suggest that AuNPs can be used for biosensing strategies, drug delivery, photothermal therapy, nanobrachytherapy, enhanced radiotherapy and CT imaging. In addition, they can be used as antibacterial and antifungal agents. This minireview focuses on the key principles, research achievements and new opportunities in the synthesis of AuNPs as well as their biological applications. In fact, the growing progress in the use of AuNPs for the diagnostic and therapeutic applications is described in this survey. Overall, a better understanding of the key aspects of the synthesis methodologies will lead to the development of new protocols that can provide ideas for more cost-effective and reliable approaches to the production of AuNPs. [ABSTRACT FROM AUTHOR]

This paper reports the one-step synthesis of Cu–Zn–Ni–CoFe2O4/reduced graphene oxide (rGO) nanocomposites via a controllable hydrothermal method using hydrazine. In addition to controlling the growth of cobalt ferrite nanoparticles, hydrazine reduces graphene oxide to graphene and enables one-step synthesis. The characterization results showed that ferrite nanoparticles were dispersed on reduced graphene oxide plates. Next, the ability to absorb electromagnetic waves by the produced nanocomposite films was investigated. The results showed that graphene significantly increases the amount of absorption of electromagnetic waves of ferrites. To achieve the maximum absorption value, the optimal amount of graphene is required, so in the present work, the highest value of reflection loss (RL) was − 17.56 dB at 10.54 GHz, which was obtained for Cu0.16Zn0.17Ni0.17Co0.5Fe2O4/rGO(0.2 g) nanocomposite. [ABSTRACT FROM AUTHOR]

The tensile strength, impact property and thermal stability of polyamide 6 (PA6) reinforced with carboxylic acid-functionalised multi-walled carbon nanotubes (MWCNTs) with 1 and 2 wt.%, and short glass fibre (SGF) with 10 and 20 wt.%, were investigated. The morphological properties were examined by SEM. The differential scanning calorimetry (DSC) was also carried out to explore the thermal stability and crystallinity of nanocomposites. For determining the optimal weight percentage of reinforcements, the response surface methodology (RSM) was used. The effect of nanotubes and weight percentages of fibre on the tensile and impact properties was investigated by analysis of variance. The results indicated that the incorporation of MWCNTs to PA6 increased the tensile and impact strength of the matrix by 16% and 24%, respectively. Also, the addition of SGFs to polyamide improved the mechanical properties. The results also showed that the nanocomposite containing 1 wt.% MWCNTs and 20 wt.% SGFs had the highest properties (66% increase for tensile and 81% increase for impact strength compared to neat PA6). The DSC results confirmed the effect of reinforcements on thermal characteristics of nanocomposites. The validation of output models of responses implies the ability of models to predict the tensile and impact behaviour of composites. [ABSTRACT FROM AUTHOR]

SiO2 is widely used in nanocomposites as reinforcement nanoparticle to enhance mechanical properties especially wear resistivity. Prior to use, surface modification with proper and sufficient coupling agent should be performed on it. Coupling agent concentration plays a key role in modification process. Purpose: In this study, the influence of 3-(glycidoloxy propyl) trimethoxy silane (GPTMS) concentration on surface modification of SiO2 nanoparticles, is experimentally investigated. Methods: The surface modification of nano-silica were performed by 30, 50, 80 and 110 wt.% of GPTMS in order to introduce the optimal GPTMS concentration to complete the process. Fourier Transformation Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Thermo Gravimetric Analysis (TGA) and X-Ray Diffraction (XRD) characterized the pure and surface modified samples; then, the results were compared to each other to achieve the aim of the research. Results: FTIR results confirmed the silanization proceed due to the silane absorption peak disappearing and shifting of the hydroxyl group bonds in to the amide bonds. This test showed that 30 wt.% GPTMS has not been sufficient for full functionalization of the NPs. According to FESEM images, it seems that the NPs were better modified by 80 wt.% GPTMS due to the least NPs aggregation and lack of coupling agent deposition on the NPs. Also, TGA illustrates that this sample has higher thermal stability because of lower weight loss (11.2%) in coupling agent decomposition temperature range: 130–380 °C. Furthermore, X-Ray Diffraction confirmed the FESEM and TGA results about the mentioned sample due to its highest crystallite size (increase 26.64% in crystallite size in comparison with the pure sample). Conclusion: So, the 80 wt.% of GPTMS introduced as the optimal concentration for surface modification of SiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

The rapid evolution of electronic and information technology has increased the performance of the electronic processors significantly. Achieving the optimal performance in a smart electronic device poses a serious challenge as the heat generated during operation will reduce the performance of the device which makes thermal management a determinant factor. Powder injection molding (PIM) is an appropriate and relatively new technology used for mass production of small delicate parts with complex shapes and desired properties. One of the latest advances in the PIM process is the production of metal matrix nanocomposites with huge industrial applications, particularly in electronics manufacturing. Manufacturing of efficient complex-shaped nanocomposites, as thermal management components (passive heatsink), could be achieved through the PIM process. On the other hand, what could pose a challenge is the presence of nanoparticles affecting on the different stages of PIM process including feedstock preparation, molding, debinding, and sintering. In this paper, the effect of nanoparticles on different stages of PIM for the production of heatsinks is investigated. Then, the manufacturing of Cu-, Al-, and Mg-based nanocomposites by powder injection molding, as heatsinks, is reviewed followed by investigating the related advantages and limitations. [ABSTRACT FROM AUTHOR]

The influence of 3-(triethoxy silyl) propyl amine (TESPA) concentration on Multi Wall Carbon Nanotubes (MWCNTs) modification, is experimentally investigated. The MWCNTs modification were performed by 150, 75 and 25 weight percent (wt.%) of TESPA with respect to MWCNTs weight and the properties of the prepared samples were compared with each other and pristine MWCNTs. The MWCNTs silylation has been confirmed by Fourier Transformation Infrared Spectroscopy due to O-H stretching absorption peak disappearing. The 75 wt.% silyl grafted MWCNTs with increasing at about 26.7% in mean value diameters size owns more uniform morphology among the samples based on Scanning Electron Microscopy images. Also, Thermo Gravimetric Analysis shows that this sample has higher thermal stability because of lower weight loss (9.97%) in coupling agent decomposition temperature range at about 119.5–480 °C. Furthermore, X-Ray Diffraction indicates that the mentioned sample has higher level of amorphous structure with 39% reduction in crystallite size in comparison with the pristine MWCNTs. So, the 75 wt.% of TESPA introduced as the optimal concentration for this type of MWCNTs modification. Introduction of silyl compounds as a proper coupling agent to modify the carbon nanotube surfaces Determination of optimal silyl compounds concentration to modify the carbon nanotube surface Cristallinity in XRD pattern can determine the success of CNTs grafted with silyl compounds [ABSTRACT FROM AUTHOR]

Objective(s): The use of cationic surface-active agents (surfactant) in the synthesis of nanoparticles, with formation of micelle, can act as a template for the formation of meso-porous silica. Changes in the concentration of surfactants can affect the structures and properties of the resulting nanoparticles. Materials and Methods: Magnetite nanoparticles were prepared as cores using the coprecipitation method. Silica shells were formed on the prepared cores using sol-gel through the single-step process. During synthesis, cetrimonium bromide (CTAB) was used as a surfactant at low (0.1 g), medium (1 g), and high concentrations (7 g), and the effects on the properties of the nanoparticles were investigated. The coreshell nanoparticles were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In addition, the surface porosities of the nanoparticles were evaluated using the BET and BJH methods. The vibrating sample magnetometer (VSM) was also employed to assess the magnetic characteristics of the synthesized samples. Results: The results of XRD indicated that the nanoparticles were composed of magnetite and silica, while the SEM and TEM images confirmed the presence of uniform spherical particles with a core-shell structure. According to the results of the VSM tests, all nanoparticles showed super-paramagnetic behaviors. Moreover, the increased concentration of CTAB led to an increment in saturation magnetization (Ms), size, and volume of the surface pores, while the specific surface area of the nanoparticles decreased. Conclusion: According to the results, the properties of the silica shell could be adjusted in terms of pore characteristics and magnetic behavior by changing the concentration of the surfactant. [ABSTRACT FROM AUTHOR]