Energy Dispersive Spectrophotometer Research Articles

Biosynthesis of silver nanoparticles using Cassia tora leaf extract and its antioxidant and antibacterial activities

A single step green synthesis of silver nanoparticles (AgNPs) from silver nitrate (AgNO3) using Cassia tora leaves extract as reducing agent by a simple and ecofriendly method in room temperature. The biosynthesized nanoparticles were characterized by UV-Vis, Scanning electron microscopy (SEM) coupled with X-ray energy dispersive spectrophotometer (EDAX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). In UV-Vis spectroscopy results, the λmax observed at 425nm. The AgNPs synthesized were spherical, hexagonal and irregular in shapes. The EDAX and XRD spectrum confirms that the presence of silver ions and crystalline nature of synthesized AgNPs. FTIR showed the functional groups such as CO, NH and CN groups involved in the reduction of Ag+ to Ag. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay was performed and it showed percentage inhibition in concentration dependent manner. The synthesized AgNPs showed antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis in different extents and the higher activity was observed in Escherichia coli.

Synthesis of TiO2 nanoparticles by electrochemical method and their antibacterial application

Titanium dioxide nanoparticles were successfully prepared by electrochemical method. The tetra propyl ammonium bromide salt was used as stabilizing agent in an organic medium viz. tetra hydro furan (THF) and acetonitrile (ACN) in 4:1 ratio by optimizing current density. The parameters such as current density, solvent polarity, distance between electrodes and concentration of stabilizers were used to control the size of nanoparticles. The synthesized titanium dioxide nanoparticles were characterized by using UV–Visible spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), energy dispersive spectrophotometer (EDS) and transmission electron microscopy (TEM) analysis techniques. TEM analysis proved a nearly tetragonal structure with size of 25–30nm which was in agreement with the result calculated from the XRD analysis. EDS analysis revealed the presence of Ti and O element. The nanoparticles were screened for their in vitro antibacterial activity against human pathogens such as gram negative Escherichia coli (E. coli), and gram positive Staphylococcus aureus strains and which proved excellent results.

Green synthesis of silver nanoparticles using seed aqueous extract of Olea europaea

Biosynthesis of silver nanoparticles with small size and biostability is very important and used in various biomedical applications. In the present work, we describe the synthesis of silver nanoparticles (Ag-NPs) using seed aqueous extract of Olea europaea (Oe) and its antibacterial activity. UV–visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray energy dispersive spectrophotometer (EDAX) were performed to ascertain the formation of Ag-NPs. It was observed that the growths of Ag-NPs are stopped within 35 min of reaction time. The synthesized Ag-NPs were characterized by a peak at 449 nm in the UV–visible spectrum. XRD confirmed the crystalline nature of the nanoparticles of 34 nm size. The XRD peaks at 38, 44, 64 and 77 can be indexed to the (1 1 1), (2 0 0), (2 2 0) and (3 1 1) Bragg’s reflections of cubic structure of metallic silver, respectively. The results confirmed that the (Oe) is a very good eco friendly and nontoxic source for the synthesis of Ag-NPs as compared to the conventional chemical/physical methods.

Influence of Deposition Temperature on Nanocrystalline CdS Thin Films: Application in Solar Cells as Antireflection Coatings

Nanocrystalline CdS thin films were successfully prepared using simple chemical bath deposition technique. Cadmium sulphate, thiourea and deionised water were used as starting precursor solution. The prepared thin films were characterized using X-ray diffractogram (XRD), Scanning electron microscope (SEM), elemental composition using energy dispersive spectrophotometer (EDAX) and optical band gap (UV-Spectroscopy).X-ray diffractogram reveals that present of cubic and hexagonal phase. The thickness, crystallite size and grain size were observed to be increase with increase operating temperature of bath while optical band gap energy slightly decreases. Effect of deposition temperature on physical, structural, microstructural, electrical and optical properties of these films was studied and presented in the present investigation. Prepared thin films shows good response towards photoconducting in presence and absent of light

Studies on Spray Pyrolised Nanostructured SnO<sub>2</sub> Thin Films for H<sub>2</sub> Gas Sensing Application

The objective of this work is to study the influence of pyrolysis temperature on structural, surface morphology and gas sensing properties of the nanostructured SnO2 thin films prepared by spray pyrolysis technique. These films were characterized for the structural, morphological and elemental composition carried by means of X-ray diffraction (XRD), scanning electron mi­croscopy (SEM) and energy dispersive spectrophotometer (EDAX). The information of crystallite size, dislocation density and microstrain is obtained from the full width-at half- maximum (FWHM) of the diffraction peaks. Effect of sprayed deposition temperature on H2 gas sensing performance and electrical properties were studied using static gas sensing system. The sensor (Tpyr. = 350°C) showed high gas response (S = 1200 at 350 °C) on exposure of 500 ppm of H2 and high selectivity against other gases The results are discussed and interpreted.

Studies on Spray Pyrolised Nanostructured SnO<sub>2</sub> Thin Films for H<sub>2</sub> Gas Sensing Application

The objective of this work is to study the influence of pyrolysis temperature on structural, surface morphology and gas sensing properties of the nanostructured SnO2 thin films prepared by spray pyrolysis technique. These films were characterized for the structural, morphological and elemental composition carried by means of X-ray diffraction (XRD), scanning electron mi­croscopy (SEM) and energy dispersive spectrophotometer (EDAX). The information of crystallite size, dislocation density and microstrain is obtained from the full width-at half- maximum (FWHM) of the diffraction peaks. Effect of sprayed deposition temperature on H2 gas sensing performance and electrical properties were studied using static gas sensing system. The sensor (Tpyr. = 350°C) showed high gas response (S = 1200 at 350 °C) on exposure of 500 ppm of H2 and high selectivity against other gases The results are discussed and interpreted.

Influence of Deposition Temperature on Nanocrystalline CdS Thin Films: Application in Solar Cells as Antireflection Coatings

Nanocrystalline CdS thin films were successfully prepared using simple chemical bath deposition technique. Cadmium sulphate, thiourea and deionised water were used as starting precursor solution. The prepared thin films were characterized using X-ray diffractogram (XRD), Scanning electron microscope (SEM), elemental composition using energy dispersive spectrophotometer (EDAX) and optical band gap (UV-Spectroscopy).X-ray diffractogram reveals that present of cubic and hexagonal phase. The thickness, crystallite size and grain size were observed to be increase with increase operating temperature of bath while optical band gap energy slightly decreases. Effect of deposition temperature on physical, structural, microstructural, electrical and optical properties of these films was studied and presented in the present investigation. Prepared thin films shows good response towards photoconducting in presence and absent of light

Facile green synthesis of silver nanoparticles using seed aqueous extract of Pistacia atlantica and its antibacterial activity

In the present work, we describe the synthesis of silver nanoparticles (Ag-NPs) using seed aqueous extract of Pistacia atlantica (PA) and its antibacterial activity. UV–visible spectroscopy, X-ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray energy dispersive spectrophotometer (EDAX) were performed to ascertain the formation of Ag-NPs. It was observed that the growths of Ag-NPs are stopped within 35min of reaction time. The synthesized Ag-NPs were characterized by a peak at 446nm in the UV–visible spectrum. XRD confirmed the crystalline nature of the nanoparticles of 27nm size. The XRD peaks at 38°, 44°, 64° and 77° can be indexed to the (111), (200), (220) and (311) Bragg’s reflections of cubic structure of metallic silver, respectively. The FTIR result clearly showed that the extracts containing OH as a functional group act in capping the nanoparticles synthesis. Antibacterial activities of Ag-NPs were tested against the growth of Gram-positive (S. aureus) using SEM. The inhibition was observed in the Ag-NPs against S. aureus. The results suggest that the synthesized Ag-NPs act as an effective antibacterial agent. It is confirmed that Ag-NPs are capable of rendering high antibacterial efficacy and hence has a great potential in the preparation of used drugs against bacterial diseases. The scanning electron microscopy (SEM), indicated that, the most strains of S. aureus was damaged and extensively disappeared by addition of Ag-NPs. The results confirmed that the (PA) is a very good eco friendly and nontoxic source for the synthesis of Ag-NPs as compared to the conventional chemical/physical methods.

Effect of molarity of precursor solution on physical, structural, microstructural and electrical properties of nanocrystalline ZnO thin films

Nanocrystalline ZnO thin films were successfully prepared using simple spray pyrolysis technique. Zinc acetate dihydrate and deionised water was used as starting precursor solution. Nanocrystalline ZnO thin films were prepared by varying molarities of precursor solution from 0·025 to 0·1M. The films were characterised using X-ray diffractogram (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and element composition was studied using an energy dispersive spectrophotometer (EDAX).The film thickness was measured using weight difference method. Thermoelectric power measurements were conducting using TEP set-up, electrical conductivity measured with the help of two probe method. The grain size and number of unit cell were observed to be increase with increase in molarities of precursor solution. From XRD, it was observed that the molarities of precursor solution goes on increasing with increases in texture coefficient for plane (002) while it is decreases for plane (101). Effect of molarities of precursor solution on physical, structural, microstructural and electrical properties of these films was studied and presented in the present investigation.

Green synthesis of silver nanoparticles using Artocarpus heterophyllus Lam. seed extract and its antibacterial activity

A novel approach for the green synthesis of silver nanoparticles (AgNPs) from aqueous solution of silver nitrate (AgNO3) by using Artocarpus heterophyllus Lam. seed powder extract (ASPE), as a reducing agent has been reported in the present work. The seed contains Jacalin, a lectin which is a single major protein representing more than 50% of the proteins from the jackfruit crude seed extract having several biological activities. The reaction of ASPE and AgNO3 was carried out in an autoclave at 15psi, 121°C for 5min and the biosynthesis of the AgNPs in solution was monitored by measuring the UV–vis spectroscopy. The morphology and crystalline phase of the NPs were determined using transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM) with X-ray energy dispersive spectrophotometer (EDAX) and Fourier transform infrared spectroscopy (FTIR). The AgNPs synthesized were generally found to be irregular in shapes with an average size 10.78nm. The FTIR spectra indicated the role of amino acids, amides group I in the synthetic process. The AgNPs thus obtained showed highly potent antibacterial activity toward Gram-positive (Bacillus cereus, Bacillus subtilis and Staphyloccocus aureus) and Gram-negative (Pseudomonas aeruginosa) microorganisms. The results confirmed that the ASPE is a very good eco friendly and nontoxic source for the synthesis of AgNPs as compared to the conventional chemical/physical methods. Therefore, A. heterophyllus seed provides future opportunities in nanomedicine by tagging nanoparticles with jacalin.

The Effect of Calcination Temperature on the Surface Evolution and Photocatalysis Activity of Co-Doped PVAc/TiO<sub>2</sub> Composite Nanofibers

The Fe3+,La3+ co-doped polyvinyl acetate(PVAc)/titanium dioxide(TiO2) composite nanofibers were firstly prepared by combining sol-gel method and electrospinning process, and then calcined under 300°Cand 600°C separately. The effect of calcination temperature on structures, surface morphologies, crystalline state, elemental composition and photocatalysis activity were characterized by scanning electron microscope (SEM), atomic force microscope (AFM), X-ray Diffraction (XRD) , energy dispersive X-ray spectroscopy (EDX) and ultraviolet-visible spectrophotometer(UV-Vis) respectively. The SEM and AFM images showed that the nanofibers were randomly distributed to form the fibrous web, the diameters and surface roughness of nanofibers were obviously changed as the calcination tempreture increasing. The EDX analysis and XRD spectra indicated the percentage of C,O,Ti elements varied as the increase of tempreture and the formation of anatase crystal form TiO2 nanofibers under 600°C.The UV-Vis curves revealed strong adsorption to methylene blue under 600°C calcination.

Novel cellulose/ NbOPO4.nH2O hybrid material from sugarcane bagasse

In recent years studies concerning the applications of lignocellulosic/ inorganic couples have resulted in the development of an interesting class of functional materials. In this work a cellulose/NbOPO4.nH2O hybrid using cellulose from surgacane bagasse was prepared and characterized in order to test for adsorption applications. The preparation process was conducted by carrying out metallic niobium dilution in hydrofluoric acid in the presence of nitric acid, then adding boric acid to form the complex and, finally, the cellulose sugar cane bagasse was added. Concentrated phosphoric acid was also inserted to precipitate hydrous niobium phosphate particles in the cellulose fiber. This material was characterized by X-ray diffractometry (XRD), thermogravimetry (TG/DTG), and scanning electronic microscopy (SEM) connected to an energy dispersive spectrophotometer (EDS). Results by SEM/EDS show that NbOPO4.nH2O was present in structure of the cellulose. During the preparation of the material, using boric acid it was observed that the formation of precipitate occurred in a shorter time than the material prepared without boric acid.

Preparation and characterization of cellulose/ hydrous niobium phosphate hybrid

In recent years, increasing attention has been directed to the use of renewable resources, particularly of sugarcane bagasse. Considering the abundant availability of such lignocellulosic materials, relatively few attempts have been made regarding their utilization. Studies about properties and morphology, heavy metal adsorption, and membranes preparation have been conduced by this research group in order to use these materials. In this paper, cellulose fibers obtained from sugarcane bagasse were bleached and modified by hydrous niobium phosphate. Hybrids (cellulose/NbOPO4.nH2O) were prepared from metallic niobium dissolved in a fluoridric/nitric (10:1) mixture, to which cellulose sugarcane bagasse was added. Afterwards a concentrated orthophosphoric acid (85mL, 85% w/w) was added to precipitate hydrous niobium phosphate particles. This material was characterized by X-ray diffraction (XRD), thermogravimetry (TG/DTG), and differential scanning calorimetry (DSC) analyses, as well as scanning electronic microscopy (SEM) coupled to an energy dispersive spectrophotometer (EDS). Morphological studies of bleached cellulose revealed different sizes and arrangement of cells, showing that NbOPO4.nH2O was present in the cellulose structure. Thermal stability of the hybrid was observed up to approximately 200°C, and the cellulose decomposed at 300°C. These data will help finding new uses for these materials.

High‐temperature sequestration of elemental mercury by noncarbon based sorbents

AbstractThis work is concerned with sequestration of elemental Hg at high temperatures (900–1100 °C) on a sorbent that is mineral based, rather than carbon based. This sorbent consists of an intimate mixture of CaO, CaCO3, and Al2O3–2SiO2, and is manufactured in industrially relevant quantities (metric tons) from residues produced in paper recycling processes. In contrast to activated carbon (AC), this noncarbon based sorbent has special advantages in that, it can actually enhance fly ash utilization for cement manufacture, rather than diminish it, as is the case for AC.Disperse phase experiments have been conducted, using an externally heated quartz tube reactor, with sorbent feeding rates ranging from 1 to 6 g/h. Preliminary results indicate that Hg removal efficiency is sensitive to sorbent feed rates and to furnace temperature. The Hg removal percentage increased with both these variables. Two mechanisms come into play: an in‐flight Hg sorption mechanism, and an Hg sorption mechanism related to sorbent deposits on the reactor wall. A maximum total (in‐flight plus deposit‐related) Hg removal efficiency of 83–90% was obtained at temperatures of 900–1100 °C. There was negligible sorption by either mechanism at temperatures below 600 °C. Results for the in‐flight mechanism alone showed a maximum sorption efficiency at ∼900 °C, whereas that on the reactor surface increased monotonically with temperature. This suggests that sorbent deactivation can occur in‐flight at high temperatures, which is in agreement with other fixed bed results obtained in this laboratory. Deactivation was not apparent for the sorbent‐related substance formed on the reactor wall. Raw and spent sorbents were analyzed by X‐ray diffraction (XRD) and scanning electron microscopy with energy dispersive spectrophotometer (SEM‐EDS) to identify the sorbent mineral transitions that seem to activate the process. The in‐flight mechanisms appear to involve (1) activation of the sorbent, caused most probably by an internal solid–solid reaction, followed by (2) Hg sorption, and (3) possible deactivation, if the temperatures are too high for longer period. Reactor surface mechanisms still remain to be elucidated. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.

Prenatal growth acceleration in maxillary deciduous canines of children with Down syndrome: Histological and chemical composition study

Previous studies have reported that the abnormal development of the second deciduous molar in Down syndrome and cerebral palsy begins before birth. In view of these results we have turned our attention to the earlier stages of dental development in utero, represented by the primary canine, in order to see if we can identify more precisely the origin and timing of developmental insults in these conditions. The study was carried out on exfoliated or extracted maxillary primary canines of children with Down syndrome (DS) and cerebral palsy (CP) and they were compared to a control group of children with no adverse medical history. Thin sections were made through the mid-sagittal bucco-palatinal axis. Using a light microscope, the width of prenatal enamel and postnatal enamel, defined by the neonatal line was measured on each section at a standardized location. The chemical composition of the enamel was then measured at three different locations using an energy dispersive spectrophotometer (ESR) in a high vacuum mode. The total enamel width in DS and controls was similar and greater than that of CP canines. Significantly more enamel was laid down prenatally in DS teeth than in controls or CP and it was more highly mineralized. These results for DS canines differ from those previously published for the later developing second primary molars. They support the hypothesis of accelerated growth in the early stages of intra-uterine development, prior to the establishment of reduced growth trajectories in the later stages. The results for CP teeth showed that more prenatal enamel was laid down prenatally than in controls. Mineralization in CP was poor during the first two trimesters and improved significantly during the last trimester. While this approach is retrospective, we propose that it may aid in identifying the onset of developmental anomalies of unknown etiology that are expressed in later life.

Microstructure and chemical composition of primary teeth in children with Down syndrome and cerebral palsy

This study was designed to test the hypothesis that prenatal growth insults leave permanent signs in the developing primary teeth that can be identified in later life. To test this hypothesis we examined exfoliated and extracted lower second primary molars of children with Down syndrome (DS) and cerebral palsy (CP). Teeth of children with no adverse medical history were used as a control group. Informed consent of parents and children was obtained in all cases. On each tooth two thin sections were cut, one bisecting the mesial cusps and one bisecting the distal cusps. Using a light microscope, the width of prenatal enamel and postnatal enamel was measured on each section at standardized locations from the dentin-enamel junction (DEJ) with the neonatal line used to distinguish between prenatal and postnatal enamel. Chemical analysis of each section was carried out using an energy dispersive spectrophotometer (ESR). The Ca/P ratios of enamel and dentin for each cusp were calculated and intercusp and intergroup differences analysed using non-parametric statistical tests. The results showed that significantly less enamel was laid down prenatally in DS and CP teeth than in the control group and that the enamel of the mesial cusps in these groups was less highly mineralised than that of the controls. The results also showed that in DS teeth growth and mineralisation of all cusps was affected. Based on these findings we propose that analysis of exfoliated deciduous teeth in developmentally challenged children may help in identifying the onset and severity of growth insults in utero and its impact on later development.

Discriminatory X‐ray mapping of two or more elements by a pulse stretch method

SUMMARYA pulse‐stretch analyser attached to an Energy Dispersive Spectrophotometer for the simultaneous mapping of two or more elements is described. The circuit for the instrument is given and examples of variable spot‐size maps which may be generated, are shown by the distribution of Si, Ti and Cr in polished grains of ilmenite, garnet, spinel and clinopyroxine.

Vapor-Liquid-Solid Whisker Growth on Lunar Breccia 15015

Possible VLS (Vapor-Liquid-Solid) whisker growth has been discovered for the first time in nature on the surface of lunar breccia 15015. Rock 15015 was collected on the Apollo 15 flight and is blocky, angular, largely glass-covered, almost 30 cm long and weighs 4.5 kg. A 62 mm2 glass-covered surface of a fragment of 15015 (15015,36) was coated with 150 Å of Au and selected areas studied in detail with a JEOLCO JSM-1 scanning electron microscope (SEM), an ARL scanning electron microprobe (EMX SM) with a QANTA/METRIX energy dispersive spectrophotometer and a Cambridge MK IIA SEM at Texas Instruments, Inc. of Dallas.