Biosynthesis of silver nanoparticles (NPs) using D. carota extract was investigated for various concentrations of D. carota extract. The aqueous silver ions were reduced into silver NPs when they interacted with D. carota extract. The silver NPs were characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. XRD measurements show that the average size of silver NPs was 20 nm. UV-visible spectra show that the surface plasmon resonance peak of silver is observed at 415 nm. FTIR measurements indicate the presence in D. carota extract of ascorbic acid which is responsible for reducing and capping bioreduced silver NPs. TEM measurement shows that most silver NPs are spherical in shape.
Posts Tagged ‘presence’
Synthesis of silver nanoparticle using D. carota extract
Posted in Nanotechnology 
Tags: aqueous-silver, ascorbic-acid, average, carota-extract, most-silver, observed-at-415, presence, resonance-peak, spectra-show, Surface, surface-plasmon, the-average 
Comments OffSpectroscopy and electron microscopy imaging of a single metal nano-object
The optical extinction spectra of single metal nano-objects measured by the spatial modulation spectroscopy technique were correlated with their image obtained by scanning electron microscopy. The results show a large influence of both the object shape and the presence of the substrate on the measured optical spectra.
Posted in Nanotechnology Tags: both-the-object, large-influence, presence, results-show, single-metal, technique-were, the-spatial, their-image Comments OffSynthesis of advanced materials for bio-oil production from rice straw by pyrolysis
Bio-oil from rice straw is produced by pyrolysis with and without solid acid catalysts. Solid acid catalysts used in rice straw pyrolysis synthesis were the diatomite acidified by an ‘atomic implantation method’ and nano-sized porous Al-SBA1-15. Catalysts were characterized by a field emission-scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), infrared spectroscopy (IR), N 2 adsorption/desorption, differential thermal analysis/thermogravimetric analysis (DTA/TGA) and NH 3 temperature programmed desorption (NH 3 -TPD). The obtained results revealed that a similar bio-oil yield (liquid product) of 44–48% can be reached by pyrolysis in the presence of solid acid catalysts at 450 °C compared to that of pyrolysis without catalyst at 550 °C. Moreover, a low yield of gas product was observed. These results show significant potential applications of solid acid catalysts for the improvement of bio-oil yield …
Posted in Nanotechnology Tags: bio-oil-yield, catalyst-at-550, diatomite, gas-product, improvement, liquid-product, presence, results-show, rice-straw, similar-bio-oil, solid-acid, the-improvement, the-presence Comments OffSynthesis of polymer-protected graphene by solvent-assisted thermal reduction process
Polyvinylpyrrolidone-protected (PVP-protected) graphene was synthesized by refluxing graphene oxide (GO) in dimethylformamide (DMF), using PVP as the dispersant. The structure and stability of this composite (DMF-rGO) were characterized using UV–vis spectroscopy, atomic force microscopy (AFM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results confirm the presence of a single sheet of DMF-rGO with PVP of 42%. This kind of chemically reduced GO has a greater solubility in water and also is more biocompatible than rGO reduced by hydrazine hydrate. This method is simple, environmentally friendly and the composite has potential applications in biology and polymer nanocomposites.
Posted in Nanotechnology Tags: atomic-force, Composite, dispersant, fourier, Kind, Method, presence, pvp, the-composite, the-presence Comments OffEdge electrospinning for high throughput production of quality nanofibers
A novel, simple geometry for high throughput electrospinning from a bowl edge is presented that utilizes a vessel filled with a polymer solution and a concentric cylindrical collector. Successful fiber formation is presented for two different polymer systems with differing solution viscosity and solvent volatility. The process of jet initiation, resultant fiber morphology and fiber production rate are discussed for this unconfined feed approach. Under high voltage initiation, the jets spontaneously form directly on the fluid surface and rearrange along the circumference of the bowl to provide approximately equal spacing between spinning sites. Nanofibers currently produced from bowl electrospinning are identical in quality to those fabricated by traditional needle electrospinning (TNE) with a demonstrated ~ 40 times increase in the production rate for a single batch of solution due primarily to the presence of many simultaneous jets. In the bowl electrospinning geometry, the elec…
Posted in Nanotechnology Tags: Bowl, circumference, fiber-formation, jet-initiation, polymer-systems, presence, Production, resultant-fiber, simple-geometry, the-production, times-increase, unconfined Comments OffElectrical control of the exciton–biexciton splitting in self-assembled InGaAs quantum dots
The authors demonstrate how lateral electric fields can be used to precisely control the exciton–biexciton splitting in InGaAs quantum dots. By defining split-gate electrodes on the sample surface, optical studies show how the exciton transition can be tuned into resonance with the biexciton by exploiting the characteristically dissimilar DC Stark shifts. The results are compared to model calculations of the relative energies of the exciton and biexciton, demonstrating that the tuning can be traced to a dominance of hole–hole repulsion in the presence of a lateral field. Cascaded decay of the exciton–biexciton system enables the generation of entangled photon pairs without the need to suppress the fine structure splitting of the exciton. Our results demonstrate how the exciton–biexciton system can be electrically controlled.
Posted in Nanotechnology Tags: biexciton, electric-fields, exciton, fine-structure, Generation, hole-repulsion, presence, relative, the-biexciton, the-exciton Comments OffA novel strategy to produce highly stable and transparent aqueous ‘nanosolutions’ of water-insoluble drug molecules
A surprisingly large proportion of new drug candidates emerging from drug discovery programmes are water-insoluble and, as a result, have poor oral bioavailability. To overcome insolubility, the drug particles are usually dispersed in a medium during product formation, but large particles that are formed may affect product performance and safety. Many techniques have been used to produce nanodispersions—dispersions with nanometre-scale dimensions—that have properties similar to solutions. However, making nanodispersions requires complex processing, and it is difficult to achieve stability over long periods. In this paper, we report a generic method for preparing drug nanoparticles with a combination of antisolvent precipitation in the presence of water-soluble matrices and spray-drying. The spray-dried powder composites (solid dispersion) are microspherical, highly stable and thus form transparent nanodispersions or so-called ‘nanosolutions’ of water-insoluble drug when simply ad…
Posted in Nanotechnology Tags: been-used, DRUG, generic-method, highly-stable, may-affect, medium-during, over-long, Paper, presence, the-presence Comments OffFlame Retardant Chemicals 10X Higher In Dogs
Chemical flame retardants found in household furniture and electronics are showing up in the blood of pet dogs at concentrations five to 10 times higher than in humans. However, the levels are lower than those found in a previous study of cats, suggesting that dogs may be a better gauge of human exposure to compounds present in the households that they share, because a dog’s metabolism is better equipped to break down the chemicals. The findings are from a study of on the presence of polybrominated diphenyl ethers ( PBDE s) in the blood of dogs and in commercial dog food. The compounds can migrate out of furniture and electronics and enter the environment. “Even though they’ve been around for quite awhile, we don’t know too much about these compounds’ toxicological effects on humans or animals,” says study co-author Marta Venier, an assistant research scientist at Indiana University. “The bottom line is that we still need to keep measuring them, particularly in homes.” Read More Paper
Posted in Nanotechnology Tags: better-equipped, Blood, Chemicals, commercial-dog, diphenyl-ethers, Environment, households, human-exposure, keep-measuring, presence, the-households, the-presence Comments OffNumerical study of the lateral resolution in electrostatic force microscopy for dielectric samples
We present a study of the lateral resolution in electrostatic force microscopy for dielectric samples in both force and gradient modes. Whereas previous studies have reported expressions for metallic surfaces having potential heterogeneities (Kelvin probe force microscopy), in this work we take into account the presence of a dielectric medium. We introduce a definition of the lateral resolution based on the force due to a test particle being either a point charge or a polarizable particle on the dielectric surface. The behaviour has been studied over a wide range of typical experimental parameters: tip–sample distance (1–20) nm, sample thickness (0–5) µm and dielectric constant (1–20), using the numerical simulation of the equivalent charge method. For potential heterogeneities on metallic surfaces expressions are in agreement with the bibliography. The lateral resolution of samples having a dielectric constant of more than 10 tends to metallic behaviour. We found a characteristi…
Posted in Nanotechnology Tags: bibliography, Dielectric, Equivalent, Lateral, Numerical, presence, sample-distance, samples-having, surfaces-having, the-dielectric, the-equivalent, the-lateral, Work Comments OffChameleon Magnets Switch On/Off
A material’s magnetism is determined by a property that all electrons possess: their spin. Electrons can have an “up” or “down” spin, and a material is magnetic when most of its electrons possess the same spin. Individual spins are akin to tiny bar magnets, which have north and south poles. Now, a study by scientists from University of Tokyo, and elsewhere in Japan, is showing that it is possible to turn a material’s magnetism on and off at room temperature. Led by researchers at Tohoku University, the team added cobalt to titanium dioxide (a nonmagnetic semiconductor) to create a new material that can transform from a paramagnet (a nonmagnetic material) to a ferromagnet (a magnetic material) at room temperature. To achieve change, the researchers applied an electric voltage to the material, exposing the material to extra electrons. These additional electrons — called “carriers” — are mobile and convey information between fixed cobalt ions that causes the spins of the cobalt electrons to align in one direction. This ability to switch a magnet “on” or “off” could be revolutionary for future spintronics (magnet- or spin-based computing technology). Conventional electronic gadgets record and read binary data as ones and zeros that are represented, in circuits, by the presence or absence of electrons. Processing information requires moving electrons, which consumes energy and produces heat. Spintronic gadgets, in contrast, store and process data by exploiting electrons’ “up” and “down” spins, which can stand for the ones and zeros devices read. Future energy-saving improvements in data processing could include devices that process information by “flipping” spin instead of shuttling electrons around. Read More Read More Paper
Posted in Nanotechnology Tags: Ability, achieve-change, between-fixed, data-as-ones, Japan, Material, presence, requires-moving, Researchers, the-researchers Comments Off