Comparative investigation of high-resolution transmission electron microscopy and Fourier transform infrared spectroscopy for GaN films on sapphire substrate

1999 ◽  
Author(s):  
Kun Li ◽  
Yong T. Hou ◽  
Zhe Chuan Feng ◽  
Soo-Jin Chua ◽  
Ming Fu Li ◽  
...  
2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
Noura El-Ahmady El-Naggar ◽  
Attiya Mohamedin ◽  
Sarah Shawqi Hamza ◽  
Abdel-Dayem Sherief

Biological method for silver nanoparticles synthesis has been developed to obtain cost effective, clean, nontoxic, and ecofriendly size-controlled nanoparticles. The objective of this study is extracellular biosynthesis of antimicrobial AgNPs using cell-free supernatant of a localStreptomycessp. strain SSHH-1E. Different medium composition and fermentation conditions were screened for maximal AgNPs biosynthesis using Plackett-Burman experimental design and the variables with statistically significant effects were selected to study their combined effects and to find out the optimum values using a Box-Behnken design. The synthesized AgNPs were characterized using UV-visible spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and energy dispersive X-ray spectroscopy. Rapid biosynthesis of AgNPs was achieved by addition of 1 mM AgNO3solution to the cell-free supernatant. The produced particles showed a single surface plasmon resonance peak at 400 nm by UV-Vis spectroscopy which confirmed the presence of AgNPs.Streptomycessp. SSHH-1E was identified asStreptomyces narbonensisSSHH-1E. Transmission electron microscopy study indicated that the shape of AgNPs is spherical and the size is ranging from 20 to 40 nm. Fourier transform infrared spectroscopy analysis provides evidence for proteins as possible reducing and capping agents. Furthermore, the biosynthesized AgNPs significantly inhibited the growth of medically important pathogenic Gram-positive and Gram-negative bacteria and yeast. The maximum biosynthesis of AgNPs was achieved at initial pH of 8, peptone of 0.5 g, and inoculum age of 48 h. The statistical optimization resulted in a 4.5-fold increase in the production of AgNPs byStreptomyces narbonensisSSHH-1E.


Author(s):  
Priyanka Mishra ◽  
Tanzeel Ahmed ◽  
Lalit Singh

Background: Silver nanoparticles (AgNPs) have been used in various medicinal products because of its anti-microbial properties. This research study has reported a simplistic, cost effective and eco-friendly method for the synthesis of Silver nanoparticles. Objective: The objective of present study was to compare the synthesis of silver nanoparticles (AgNPs) from various parts of Citrus maxima fruit like pulp, peel and seed. Methodology: The synthesized nanoparticles were characterized by the use of UV-visible spectroscopy, fourier transform infrared spectroscopy and transmission electron microscopy. Time-dependent synthesis of AgNPs was studied spectrophotometrically. UV–visible spectrophotometer was used to confirm the synthesis of AgNPs which showed maximum absorption at 410 nm, 420 nm and 430 nm respectively. Expected Results: Fresh peel extract exhibited the highest concentration of silver nanoparticles in comparison to pulp and seed. Fourier-transform infrared spectroscopy (FTIR) spectra analysis confirmed the presence of possible functional groups in AgNPs which can be responsible for reduction of nanoparticles. Morphological characters of AgNPs were analyzed using transmission electron microscopy (TEM) depicting the particles size as 12.58-47.80 nm. The antibacterial property of synthesized AgNPs was analyzed viz Escherichia coli (MTCC 1687) and Staphylococcus aureus (MTCC 902), specify them to be effective against both gram positive and gram negative bacteria. Conclusion: These results suggested that the fresh peel extract of Citrus maxima is a high-quality bioreductant for the synthesis of silver nanoparticles and have prospective for various biomedical applications.


2017 ◽  
Vol 70 (6) ◽  
pp. 691 ◽  
Author(s):  
Yu Shen ◽  
Fumin Wang ◽  
Chaoqun Yang ◽  
Xubin Zhang

Hierarchical HZSM-5 were synthesised by controlled desilication in alkaline medium and characterised by field-emission scanning electron microscopy, X-ray diffraction, transmission electron microscopy, inductively coupled plasma–atomic emission spectrometry, N2 adsorption–desorption, and Fourier transform infrared spectroscopy. The catalytic performance of HZSM-5 towards the selective oxidation of 2,3,6-trimethylphenol by H2O2 was evaluated. Recyclability tests were also carried out. The results showed that 2,3,5-trimethyl-1,4-benzoquinone was produced in high yields (i.e. 90 %), corresponding to a 2,3,6-trimethylphenol percentage of 98 %. The N2 adsorption–desorption and XRD studies suggested that mesopores with an average size of 5 nm were produced and that the structural character of HZSM-5 was preserved after desilication. Transmission electron microscopy analysis of the spent catalyst indicated good stability of the hierarchical structure. The Fourier transform infrared spectroscopy studies revealed the development of acid sites. The combined results suggested that the nature of the solvent, intrinsic acidity, and shape selectivity of the hierarchical structure of the catalyst ensured high catalytic properties.


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