Search

The synthesis of silver nanoparticles (Ag-NPs) was achieved by a simple green chemistry procedure using sodium alginate (Na-Alg) under ultrasonic radiation as a stabilizer and physical reducing agent. The effect of radiation time on the synthesis of Ag-NPs was carried out at room temperature until 720 min. The successful formation of Ag-NPs has been confirmed by UV-Vis, XRD, TEM, FESEM-EDX, zeta potential, and FT-IR analyses. The surface plasmon resonance band appeared at the range of 452–465 nm that is an evidence of formation of Ag-NPs. The XRD study showed that the particles are crystalline structure in nature, with a face-centered cubic (fcc) structure. The TEM study showed the Ag-NPs have average diameters of around 20.16–22.38 nm with spherical shape. The FESEM-EDX analysis confirmed the spherical shape of Ag-NPs on the surface of Alg and the element of Ag with the high purity. The zeta potential showed high stability of Alg/Ag-NPs especially after 720 min irradiation with value of −67.56 mV. The FT-IR spectrum confirmed that the Ag-NPs have been capped by the Alg with van der Waals interaction. The Alg/Ag-NPs showed the antibacterial activity against Gram-positive and Gram-negative bacteria. These suggest that Ag-NPs can be employed as an effective bacteria inhibitor and can be applied in medical field. [ABSTRACT FROM AUTHOR]

The synthesis of gold nanoparticles (Au-NPs) is performed by the reduction of aqueous gold metal ions in contact with the aqueous peel extract of plant, Garcinia mangostana (G. mangostana). An absorption peak of the gold nanoparticles is observed at the range of 540–550 nm using UV-visible spectroscopy. All the diffraction peaks at 2θ = 38.48°, 44.85°, 66.05°, and 78.00° that index to (111), (200), (220), and (311) planes confirm the successful synthesis of Au-NPs. Mostly spherical shape particles with size range of 32.96 ± 5.25 nm are measured using transmission electron microscopy (TEM). From the FTIR results, the peaks obtained are closely related to phenols, flavonoids, benzophenones, and anthocyanins which suggest that they may act as the reducing agent. This method is environmentally safe without the usage of synthetic materials which is highly potential in biomedical applications. [ABSTRACT FROM AUTHOR]

In this research, gold nanoparticles (Au-NPs) are biosynthesized from tetrachloroaurate (AuCl4−) aqueous solution through a simple and ecofriendly route using water extract of black Camellia sinensis leaf (C. sinensis L.) which acted as a reductant and stabilizer simultaneously. The prepared gold nanoparticles are characterized using UV-visible spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). Also, determination of the accurate predictor model for chemical reactions is particularly important because of high cost of the chemical materials and measurement devices. While the artificial neural networks (ANNs) are one of the appropriate tools to forecast any phenomena, due to the low number of data set related to chemical experimental was caused to provide appropriate model is a time-consuming iterative process. With the aim to improve the accuracy of the ANN model and overcome the local convergence of this problem, a global search technique, biogeography-based optimization (BBO) method which integrated by chaotic map is employed. The improved model showed minimum mean squared error (MSE) of 0.0134 and maximum coefficient of determination (R2) equal to 0.9822 compared with several other famous ANN training algorithm, utilizing output experimental data obtained from biosynthesis proceeding. [ABSTRACT FROM AUTHOR]

Iron oxide nanoparticles (Fe3O4-NPs) were synthesized using chemical coprecipitation method. Fe3O4-NPs are located in interlamellar space and external surfaces of montmorillonite (MMT) as a solid supported at room temperature. The size of magnetite nanoparticles could be controlled by varying the amount of NaOH as reducing agent in the medium. The interlamellar space changed from 1.24 nm to 2.85 nm and average diameter of Fe3O4 nanoparticles was from 12.88nm to 8.24 nm. The synthesized nanoparticles were characterized using some instruments such as transmission electron microscopy, powder X-ray diffraction, energy dispersive X-ray spectroscopy, field emission scanning electron microscopy, vibrating sample magnetometer, and Fourier transform infrared spectroscopy. [ABSTRACT FROM AUTHOR]

The goal of this study was to investigate the effect of modified rice straw (ORS) on the mechanical and thermal properties of modified rice straw/polycaprolactone composites (ORS/PCL-Cs). The composites (Cs) of polycaprolactone (PCL) with ORS were successfully synthesized using the solution-casting method. The RS modified with octadecylamine (ODA) as an organic modifier. The prepared composites were characterized by using powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and Fourier transforms infrared spectroscopy (FT-IR), and mechanical properties were investigated. Composites of ORS/PCL showed superior mechanical properties due to greater compatibility of ORS with PCL. TheXRDresults showed that the intensity of the peaks decreasedwith the increase ofORS content from1.0 to 7.0wt.%in comparison with PCL peaks. Tensile measurement showed an increase in tensile modulus but a decrease in tensile strength and elongation at break as the ORS contents are increased from 1.0 to 7.0wt.%; on the other hand, tensile strength was improved with the addition of 5.0wt.% of ORS.Thermal stability was decreased with the increase of ORS contents. SEM micrograph indicated good dispersion of ORS into the matrix, and FT-IR spectroscopy showed that the interaction between PCL and ORS is physical interaction. [ABSTRACT FROM AUTHOR]

Nickel nanoparticles were dispersed uniformly in a graphene oxide solution, using a laser ablation technique with different ablation times that ranged from 5 to 20 minutes. The results indicate that the nickel nanoparticle sizes inside the graphene oxide decreased, and the volume fraction for the nickel nanoparticles in the graphene oxide increasedwith an increasing ablation time. Further, using Fourier Transform Infrared Spectroscopy, the nickel nanoparticles in the graphene oxide demonstrate greater stability from possible Agglomeration when the nanoparticle was capped with oxygen from the carboxyl group of the graphene oxide. The thermal effusivity of the graphene oxide and nickel nanoparticle graphene oxide composite was measured using a photoacoustic technique. The concentration of graphene oxide shifted from0.05mg/L to 2mg/L, and the thermal effusivity increased from0.153W·s1/2 ·cm-2 ·K-1 to 0.326W·s1/2 ·cm-2 ·K-1. In addition, the thermal effusivity of the nickel nanoparticles graphene oxide composite increased with an increase in the volume fraction of nickel nanoparticles from 0.1612W·s1/2 ·cm-2 ·K-1 to 0.228WW·s1/2 ·cm-2 ·K-1. [ABSTRACT FROM AUTHOR]

Nanocomposites of poly-3-hydroxybutyrate/poly(butyleneadipate-co-terephthalate)/layered double hydroxide (PHB/PBAT/LDH) were prepared from a binary blend of PHB/PBAT and stearate-Zn3Al LDH via a solution casting method using chloroform as solvent in this study. The pristine Zn3Al LDH was synthesized from nitrate salts solution at pH 7 by using coprecipitation technique and then was modified by stearate anions surfactant via ion exchange reaction. As a result, the basal spacing of the LDH was increased from 8.77 to 24.94 Å after the modification. Intercalated nanocomposites were formed due to the presence of diffraction peak in XRD diffractograms. The infrared spectrum of stearate-Zn3Al LDH exhibited the existence of stearate anions in the synthesized Zn3Al LDH. Mechanical properties with 2 wt% stearate-Zn3Al LDH loading nanocomposites showed 56 wt% improvements in elongation at break compared to those of the blend. [ABSTRACT FROM AUTHOR]

Synthesis of copper nanoparticles was achieved by laser irradiation of copper plate in walnut oil. The copper plate was irradiated using Nd:YAG pulse laser at different ablation time from 5 to 50 minutes, and the prepared samples were characterized using analytical methods to find the optical absorption, morphology, particle size, and capping of copper nanoparticles with walnut oil. Consequently, the absorption peak appeared at about 615, 606, 588, 576, and 561 nm; and the nanoparticles formed in spherical shape in walnut oil. The particle size varied from 25 to 4.01 nm, and the tail of the carbonyl band capped the copper nanoparticles through the electron transfer from the carboxylic group to copper nanoparticles. The refractive indices of the nanofluid were measured using a surface plasmon resonance technique and changed from 1.4691 + 0.008i to 1.4682 + 0.043i as the volume fraction increased from 0.0257 × 10−5 to 1.26 × 10−5. Consequently, the laser ablation method is environmentally sensitive (i.e., green) and thus is suitable for the fabrication of copper nanoparticles in walnut oil without any agent. [ABSTRACT FROM AUTHOR]

A chemical reduction method was employed for the synthesis of copper nanoparticles stabilized by nanocrystalline cellulose (NCC) using different concentrations of copper salt in aqueous solution under atmospheric air. CuSO4·5H2O salt and hydrazine were used as metal ion precursor and reducing agent, respectively. Ascorbic acid and aqueous NaOH were also used as an antioxidant and a pH moderator, respectively. The number of CuNPs increased with increasing concentration of the precursor salt. The formation of copper nanoparticles stabilized by NCC (CuNPs@NCC) was investigated by UV-visible spectroscopy (UV-vis), where the surface absorption maximum was observed at 590 nm. X-ray diffraction (XRD) analysis showed that the CuNPs@NCC are of a face-centered cubic structure. Moreover, the morphology of the CuNPs@NCC was investigated using transmission electron microscope (TEM) and field emission scanning electron microscope (FESEM), which showed well-dispersed CuNPs with an average particle size less than 4 nm and the shape of CuNPs was found to be spherical. Energy dispersive X-ray spectroscope (EDS) also confirmed the presence of CuNPs on the NCC. The results demonstrate that the stability of CuNPs decreases with an increasing concentration of the copper ions. [ABSTRACT FROM AUTHOR]