سال:1394 | دوره: | شماره: |تعداد مقالات:11

Nanocolloidal poly (aniline-co-o-toluidine) particles were synthesized by dispersion polymerization using different weight ratios of steric stabilizer poly (styrene sulfonic acid). The dispersed nanocolloidal particles ranging from 10 to 100 nm were inspected by transmission electron microscopy and particle size analyzer. The strong doping level of particles at higher weight ratios of stabilizer was analyzed by elemental analysis. The functional groups of particles were identified by Fourier transform-infrared spectra. A reduction of the conjugation length in the particles leads to the homogeneous mixture of phases which was confirmed by scanning electron microscopy and UV-visible spectra. The blue shift polaron band has confirmed the change in conjugation length of the particle. High thermal stability of particles was examined by thermogravimetry analysis.

Magnesium aluminate spinel nanoparticles with different concentration of alumina (x=0.1, 0.2, 0.3, 0.4 and 0.54) are synthesized by solid state reaction method. The synthesized products are characterized by powder X-ray diffraction and UV–Vis spectroscopy. The prepared nanoparticles exhibit a cubic structure with average crystallite size 25.4, 30.1, 31.2, 29.6 and 19.5 nm, respectively. The band gap values of magnesium aluminate spinel nanopartciles are found to increases with increase in alumina concentration (x=0.1 to 0.54). Photocatalytic studies of the magnesium aluminate spinel nanoparticles are done by taking methylene blue as pollutants. Their degradation behavior has been discussed.

Various empty carbon fullerenes (Cn) with different carbon atoms have been obtained and investigated.Cephalosporin antibiotics and its derivatives have important medicinal properties. The b-lactam class of antibiotics has a broad spectrum of antimicrobial properties.Their antibacterial and pharmacokinetic properties have wide therapeutic applications. Topological indices have been successfully used to construct effective and useful mathematical methods to establish clear relationships between structural data and the physical properties of these materials. In this study, the number of carbon atoms in fullerenes was used as an index to establish a relationship between the structures of cefadroxil, cefepime, cephalexin, cefotaxime, cefoperazone and ceftriaxone (b-lactam antibiotics) and fullerenes (Cn, n=60, 70, 76, 82 and 86), which create [cefadroxil] Cn, [cefepime] Cn, [cephalexin] Cn, [cefotaxime] Cn, [cefoperazone]...

A series of ZnO: Sm films with Sm content of 0–1.0 at.% were deposited by a chemical solution deposition.The deposited films were characterized by X-ray diffraction, field emission scanning electron microscopy, UV-Vis and luminescent spectrophotometry, and electrical resistance measurement. The experiments revealed that the Sm doping first increased and then decreased the optical transmittance, band gap, and n-type conductivity with increasing Sm content. The film with the Sm content of 0.75 at.% showed optimal optical and electrical properties. The maximal band gap widening was about 0.19 eV. The resistance decrease of~20 times was observed. The photoluminescence measurement indicated that the films showed a strong near band gap emission and a blue-green emission related to intrinsic defect. The refractive index, extinction coefficient, and dielectric constant of the films were calculated with the transmittance and reflectance spectra.

Described here is a simplified method for fabrication of DNA nanotubes using a minimum numbers of staple oligomers for DNA origami. For this purpose, the cylindrical nanotemplates with two sticky ends have been designed using caDNAno software. Then, the nanostructures were shaped in an optimized experimental condition via an origami-based self-assembly reaction. Finally, the produced nanostructures were joined together through their sticky ends using a ligase enzyme. Transmission electron microscope confirmed fabrication of these elongated nanotubes. In addition, high-resolution microscopy of DNA nanotubes by scanning tunnelling microscope indicated efficient attachments of the primarily DNA nanostructures via their sticky ends. The results demonstrated that a ligase treatment of cylindrical DNA nanostructures with the sticky ends made DNA nanotubes with standard shapes using minimum numbers of staples.

Gold nanoparticles (AuNPs) were prepared from HAuCl4 using gum kondagogu, by adopting green synthesis, which is a simple, low cost and ecofriendly technique. The gum kondagogu (Cochlospermum gossypium) serves as both reducing agent and stabilizer. The formation of the AuNPs was identified through the change in the color of the solution from yellow to red. The synthesized AuNPs were characterized by various techniques.The green synthesized AuNPs were found to be stable in the pH range pH 2–12 and up to the concentration of 5 M NaCl. The stabilized AuNPs demonstrated the excellent catalytic activity in reducingp-nitrophenol to p-aminophenol in the presence of a reducing agent, NaBH4.The effects of catalyst dose and temperature were studied.The synthesized, new gum-based catalyst was very efficient, easy to prepare, stable, cost-effective and ecofriendly. The synthesized AuNPs showed good antibacterial activity.

Density functional theory and Time-dependent density functional theory (TDDFT) -based calculations were performed on surface-passivated Silicon nanocrystals (SPSNs) of different sizes. The surface passivation was achieved using H, F and Cl atoms. Various properties of the resulting optimized structures SinHn, Sin Hn-1F and SinHn-1Cl (n=20, 24, 26 and 28) like binding Energy, dipole moment, HOMO–LUMO gap, vibrational IR spectra and absorption wavelengths were determined. Surface passivation studies reveal that all the SPSNs are insulators...

L-Arginine-passivated Nd3+ and Li+ co-doped CdS quantum dots (QDs) were synthesized by chemical precipitation method. Ultraviolet–visible absorption spectra of prepared QDs show absorption in the range of 477–450 nm indicating huge blue shift in energy band gap as compared to the bulk CdS due to quantum confinement effect. The optical band gap is found increasing from 2.44 to 2.97 eV as the doping concentration increased from 1 to 5 wt%. Photoluminescence spectra showed that codoped CdS QDs are highly luminescent and emit multiple intense violet (362, 371, 385, 395 nm) and blue (422, 445, 456 and 465 nm) coloured peaks with increasing intensity with co-dopant concentration. Fourier transform infrared study confirmed the interaction between CdS nanoparticles andL-arginine ligands. The structural and morphologicalstudy revealed the formation of orthorhombic crystal structure. The size of CdS QDs, as analysed by X-ray diffraction and high-resolution transmission electron microscopy, is found reducing with co-dopant concentration.The energy dispersive X-ray analysis shows no impurities present except dopants indicating high purity of the prepared samples. Based on the results, we proposed that this material is a new class of luminescent material suitable for optoelectronics devices’ application, especially in light emitting devices, electroluminescent devices and display devices.

The adsorption behavior of ethyl acetylene (C4H6) molecule with external surface of (5, 0), zigzag aluminum nitride nanotube (AlNNT) was studied using density functional calculation, and it was found that the adsorption energy (Ead) of ethyl acetylene on the surface of pristine nanotubes is about-10.85 kcal/mol. However, when nanotubes have been doped with a P atom, the adsorption energy of ethyl acetylene molecule was decreased.Calculation showed when the nanotube is doped by P atom, the adsorption energy range is about-8.05 to -10.64 kcal/mol, and the amount of HOMO/LUMO energy gap (Eg) will reduce significantly. Pristine AlNNT is a suitable adsorbent for ethyl acetylene and can be used in separation processes or adsorption of ethyl acetylene toxic gas from environmental systems. Also the AlNNT doped by P in the presence of ethyl acetylene, an electrical signal is generated directly and therefore can potentially be used for ethyl acetylene toxic gas sensors for detection in environmental systems.

In this study, graphene nano-sheets were grown and synthesized on copper foils and the structure was analyzed with XRD, FTIR and SEM. After that, 1 wt% low-layer graphene nano-sheets were added to water and stabilized by sodium dodecyl sulfate (SDS). Prepared nano-fluid was then used in hydrate formation of natural gas at 1000 psig and 4oC. The results were compared with a SDS/water system and observed that graphene nanosheets had reduced the dissolution time 19.2 %, induction time 54.7 % and the amount of gas storage is increased 7.6 %. Hydrate stability test showed that the hydrate stability is also increased 5.9 %.

Rapid removal of noxious synthetic dyes from wastewater is of great concern in the scientific research field, this is due to the expansion of harmful effects of synthetic dyes traces in water streams on the environment and human health with the exponential rise in concentration of synthetic dye globally and demand in various industries that coincided with the implantation of more stringent water quality standards.Various technologies have been applied for the removal of synthetic dye from wastewater, including adsorption technology, which has a great potential in treating varieties of synthetic dyes. This article comprehensively reviews the latest progress in the development of carbon nanotubes (CNTs) and their applications for the removal of synthetic dyes from wastewater, including functionalized of CNTs and their researched counterparts. The emerging trends in the development of alternative adsorbents with different substrates, morphologies, and functional groups are also elucidated.