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 Applied Nanoscience   [7 followers]  Follow       Open Access journal    ISSN (Print) 2190-5509 - ISSN (Online) 2190-5517    Published by SpringerOpen  [224 journals]
• DNA–carbon nano onion aggregate: triangle, hexagon, six-petal flower

• Abstract: The interaction between calf-thymus (CT) dsDNA and water soluble carbon nano onion (wsCNO) in water follows denaturation of dsDNA (double stranded) to ssDNA (single stranded) as monitored by optical spectroscopy. The ssDNA concomitantly wraps the spiky surface of wsCNO to create triangular aggregate as the building block as observed by time-dependent SEM images. These triangles further aggregate leading to six-petal flower arrangement via hexagon and finally reach a dead end network as imaged by SEM and optical fluorescence microscopy. The dead-end network aggregate lost the intrinsic optical property of DNA suggesting complete loss of its activity.
PubDate: 2017-05-17

• A study of the optical band gap of zinc phthalocyanine nanoparticles using
UV–Vis spectroscopy and DFT function

• Abstract: In the present work, we used the ultraviolet–Visible (UV–Vis) spectroscopy technique to find the optical band gap of zinc phthalocyanine nanoparticles (ZnPc-NP) experimentally. Moreover, we used a time-dependent density functional theory (TDDFT) to simulate the UV–Vis absorption spectrum of ZnPc molecule in gas and solution phases. The ZnPc-NP absorption spectrum shows a shift toward higher energies compared to the bulk ZnPc. The simulated UV–Vis and the experimental nanoparticle’s spectrum were found to have a good agreement. The ZnPc energy band gap from the DFT calculations shows how it’s possible to get wider range of energy band gap for the ZnPc. The ZnPc-NP’s size and shape were examined using the transmission electron microscope (TEM).
PubDate: 2017-04-27

• Blood flow analysis with considering nanofluid effects in vertical channel

• Abstract: Manipulation of heat convection of copper particles in blood has been considered peristaltically. Two-phase flow model is used in a channel with insulating walls. Flow analysis has been approved by assuming small Reynold number and infinite length of wave. Coupled equations are solved. Numerical solution are computed for the pressure gradient, axial velocity function and temperature. Influence of attention-grabbing parameters on flow entities has been analyzed. This study can be considered as mathematical representation to the vibrance of physiological systems/tissues/organs provided with medicine.
PubDate: 2017-04-25

• Photocatalytic degradation of methyl orange dye by pristine titanium
dioxide, zinc oxide, and graphene oxide nanostructures and their

• Abstract: Discharge of azo dyes by textile and allied industries to the environment is a growing problem. Degradation of an azo dye, methyl orange (MO), was tested in simulated wastewater with different oxide nanomaterials acting as photocatalysts under visible light. Titanium dioxide (TiO2), zinc oxide (ZnO), and graphene oxide (GO) were synthesized, characterized, and applied for adsorptive and photocatalytic removal of the dye. Factors such as initial concentration of MO and size of nanoparticle photocatalyst were varied to determine the optimum conditions for dye removal. Finally, nanocomposites of the three materials (GO–TiO2–ZnO) were synthesized and tested for its photocatalytic performance. The composition of the individual oxide in the nanocomposite was then varied to achieve the best photocatalytic performance.
PubDate: 2017-04-22

• Effect of Mg doping and sintering temperature on structural and
morphological properties of samarium-doped ceria for IT-SOFC electrolyte

• Abstract: Samples of Sm and Mg co-doped ceria electrolyte of Ce1−x Sm x−y Mg y O2−δ (x = 0.2; y = 0.00, 0.05, 0.1, 0.15, and 0.175) were synthesized by sol–gel process. The prepared samples were sintered at 1100 and 1400 °C for 4 h. The bulk densities were measured by Archimedes method. XRD measurements indicate that the synthesized samples were in single-phase cubic fluorite structure (space group Fm3m). The cell parameters decrease with the concentration of Mg, and 2θ values slightly shift towards right. The particle sizes obtained were between 7.14 and 17.44 nm. The sintered sample achieved 95% of theoretical density. FTIR spectra of samples sintered at 1400 °C indicates weak interactions between 3550–3400 cm−1 and 1600–1300 cm−1 are attributed to O–H stretching modes and strong bonds 850–450 cm−1 are assigned to characteristic Ce–O vibrations. The surface morphology and chemical composition were analyzed by SEM and EDS, SEM micrographs show spherical faceted grains, and the samples were crack free, dense material with some pores on surface which are inconsistent with density results. The average grain size obtained was 0.5 μm. Particle size obtained by TEM was in agreement with that obtained by XRD. The high-density ceria co-doped ceramic can be used as electrolyte in SOFC.
PubDate: 2017-04-21

• Synthesis and magnetic induction heating properties of Gd-substituted
Mg–Zn ferrite nanoparticles

• Abstract: Gadolinium-substituted magnesium–zinc ferrite (Mg x Zn1−x Gd y Fe2−y O4) nanoparticles with different metal compositions for x between 0 and 1 and y between 0 and 0.06 were synthesized via coprecipitation of metal hydroxides, followed by calcination. Their crystal structure was characterized via X-ray diffraction analysis, confirming that the Gd-substituted Mg–Zn ferrite samples had a single-phase spinel structure. The metal composition significantly affected the crystal structure, including the lattice parameters and crystallite size. Scanning electron microscopy (SEM) showed that the ferrite samples had a diameter of approximately 50–200 nm. Furthermore, the temperature rise in an alternating magnetic field was measured, and the magnetic induction heating properties were evaluated using the specific absorption rate (SAR) determined from the temperature profile. The SAR significantly varied depending on the compositions of x and y. When x = 0.5 and y = 0.02, the SAR was found to be at maximum. This reveals that the compositions can control the magnetic induction heating properties. The results suggest that Gd-substituted Mg–Zn ferrite nanoparticles are promising candidates for magnetic hyperthermia applications.
PubDate: 2017-04-19

• A molecular dynamics investigation into the adsorption behavior inside
{001} kaolinite and {1014} calcite nano-scale channels: the case with
confined hydrocarbon liquid, acid gases, and water

• Abstract: A set of molecular dynamics simulations was conducted, as the first comparative study of the adsorption behavior of liquid hydrocarbon/acid gases/water molecules over $$\{ 10\bar{1}4\}$$ calcite surface and {001} octahedral kaolinite surface in nano-confined slit. According to atomic z-density profiles, hydrocarbon molecules have higher tendency towards the $$\{ 10\bar{1}4\}$$ calcite surface than the {001} octahedral kaolinite surface. In addition, water molecules form stronger adsorption layer over calcite surface than kaolinite. In contrast, acid gas molecules have higher tendency towards kaolinite surface than calcite. This behavior was spotted within nanometer-sized slit pores. The results also point to reduction in self-diffusion coefficient of molecules with strong adsorption over mineral surfaces in nano-confined environment.
PubDate: 2017-04-12

• Sonication-assisted synthesis of polystyrene (PS)/organoclay
nanocomposites: influence of clay content

• Abstract: This article presents the synthesis of a series of polystyrene (PS)/organoclay nanocomposite films consisting of different contents of clay (1–7 wt%) by sonication-coupled solvent-blending technique. The prepared PS nanocomposite films were characterized using various techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA). The XRD and TEM results revealed the formation of exfoliated nanocomposites at lower loading of organoclay (<5 wt%). The presence of various functional groups in the organoclay and PS/organoclay nanocomposite was verified by FTIR spectra. The thermal stability of PS nanocomposites was significantly improved as compared to pristine PS, which is evident from TGA analysis. When 10% mass loss was chosen as a point of reference, the thermal degradation temperature of PS nanocomposite holding 7 wt% of organoclay was found to be 30 °C more over pristine PS. The thermal kinetic parameters such as activation energy (E a), pre-exponential factor (A), and the order of reaction (n) were determined by employing the Coats–Redfern model. Thermal degradation reaction mechanism of PS nanocomposites was also investigated.
PubDate: 2017-04-11

• Optimized interaction parameters for metal-doped endohedral fullerene

• Abstract: Interaction between various atoms doped inside C60 can be modeled using interaction potentials and, thus, cohesive energy and other physical constants may be calculated. In case of metal-doped fullerene total energy may be written in terms of three different types of interactions, namely carbon–carbon interaction, metal–metal interaction and carbon–metal interaction. Brenner potential, Gupta potential, and Lennard–Jones potentials have been used to model these interactions respectively. Generally, parameters used in these model potentials are not readily available and need to be fine-tuned for different dopants. In this paper, we have deduced/optimized these interaction parameters for Cu, Ag, Al and Ga doped C60 comparing with our Density Functional Theory (DFT) results and hence predicting the stability of various metal-doped fullerenes. Total energy calculations reveal that a maximum of nine copper atoms can be doped inside the fullerene cage and form stable complex without distorting the cage significantly. As we add more number of Cu atoms in the fullerene molecule, cage structure breaks down. In the same way, we have done calculations for Ag, Al and Ga atoms doped inside the fullerene molecule and found that the maximum of eight, nine, nine atoms can form stable complexes.
PubDate: 2017-04-10

• ZnO nanoparticles (ZnO-NPs) and their antifungal activity against coffee
fungus Erythricium salmonicolor

• Abstract: In this work, a methodology of synthesis was designed to obtain ZnO nanoparticles (ZnO NPs) in a controlled and reproducible manner. The nanoparticles obtained were characterized using infrared spectroscopy, X-ray diffraction, and transmission electron microscopy (TEM). Also, we determined the antifungal capacity in vitro of zinc oxide nanoparticles synthesized, examining their action on Erythricium salmonicolor fungy causal of pink disease. To determine the effect of the quantity of zinc precursor used during ZnO NPs synthesis on the antifungal capacity, 0.1 and 0.15 M concentrations of zinc acetate were examined. To study the inactivation of the mycelial growth of the fungus, different concentrations of ZnO NPs of the two types of synthesized samples were used. The inhibitory effect on the growth of the fungus was determined by measuring the growth area as a function of time. The morphological change was observed with high-resolution optical microscopy (HROM), while TEM was used to observe changes in its ultrastructure. The results showed that a concentration of 9 mmol L−1 for the sample obtained from the 0.15 M and at 12 mmol L−1 for the 0.1 M system significantly inhibited growth of E. salmonicolor. In the HROM images a deformation was observed in the growth pattern: notable thinning of the fibers of the hyphae and a clumping tendency. The TEM images showed a liquefaction of the cytoplasmic content, making it less electron-dense, with the presence of a number of vacuoles and significant detachment of the cell wall.
PubDate: 2017-04-09

• Enhance the figure of merit for flexible thermoelectric materials by
reducing the screening effect

• Abstract: A flexible thermoelectric materials (FTEM) films based on Polydimethylsiloxane as the polymer matrix and (Zinc Oxide, Polyaniline and multi wall Carbon nanotube) as the fillers were prepared. The fillers were prepared using modified sol–gel method to enhance the distribution of the nanoparticles inside the polymer matrix and good performance. The Seebeck coefficient, electrical conductivity, thermal conductivity and dielectric measurements were carried out for all of the four films. The Seebeck coefficient results for the investigated films were −40, 220, −120, 280 μv/k° at 200 °C for FTEM 1, 2, 3, 4 alternatively. The sign and the value for the Seebeck measurements show a great dependent on the filler type add to the film. The electrical conductivity results for the films was varied from 2 × 10−8 to 0.14 S/m and strongly dependent on the fillers electrical conductivity. The less dependent on the thermal conductivity of the fillers and a slight change in the thermal conductivity value of the films were obtained. The figure of merit for the films was ranged from 1.14 × 10−16 to 3.134 × 10−8. The dielectric results ranged from 4 to 3500. Reducing the screening effect will increase the electrical conductivity and Seebeck coefficient values.
PubDate: 2017-04-07

• Assessment of toxicity in fresh water fish Labeo rohita treated with
silver nanoparticles

• Abstract: Silver nanoparticles (17.78 ± 12.12 nm) were synthesized by the reduction of 0.5 M silver nitrate using formaldehyde as reducing and triethylamine as promoting and stabilizing agent. The particles were grain like agglomerates with spherical, centered-face cubic and crystalline in nature. The sample was highly pure with amine (NH) as associated and capping molecules. Further, the genotoxicity and oxidative stress of these particles were evaluated using Labeo rohita (L. rohita) as genetic model exposed (10–55 mg L−1 dose) through aquatic medium for 28 days. The cells were produced with micronuclei, fragmented, lobed and buds nuclei in dose dependent manner. The highest incidence of comet was recoded (27.34 ± 5.68) at 55 mg L−1 Ag-NPs and 14 days treatment. Then frequency was decreased to 22.65 ± 6.66% after 28 days due to complex repair mechanism. Moreover, the treatment also produces the oxidative stress and disturbs the level of GST in gill and liver tissue. There was a sharp decline in the activities of GST and this decrease of activity increase the MDA content. Further, the elevated level of GSH represents that the liver has started defensive mechanism against oxyraidcals. This study concluded, Ag-NPs are genotoxic in nature and produce micronuclei, comet cells and also induces oxidative stress in aquatic organisms.
PubDate: 2017-04-05

• Synthesis of ammonium and sulfate ion-functionalized titanium dioxide for
photocatalytic applications

• Abstract: Due to high band gap energy the optimum photocatalytic activities can only be achieved under UV light, thus limiting the practical application of TiO2. In this study, a method combining NH4 +/SO4 2−-functionalization technique and post-treatment was developed and successfully applied to synthesize photoactive TiO2 samples which showed higher photocatalytic activity than the commercial P25 TiO2 under visible light radiation. The results also showed that the addition of (NH4)2SO4 surface functionalization on TiO2 increased the photocatalytic activity, which could be due to the combined effect of crystallinity and band gap energies. Moreover, the results showed that calcination temperature was inversely proportional to photocatalytic activity. The degradation efficiency for methylene blue under visible light was improved by ~2 times from 10.7% for P25 nano Degussa TiO2 to 20.2% for the synthesized sample. The band gap energies were also reduced from 3.7 to 3.4 eV (under UV–Vis direct transition mode) indicating a red shift towards higher wavelength.
PubDate: 2017-03-14

• Effects of concentration on CdO films grown by electrodeposition

• Abstract: Thin films of CdO were synthesized by electrodeposition via chronoamperometry. The concentrations of aqueous solutions of Cd(NO3)2 were chosen between 0.005 and 0.08 M. It was thought that the reaction rate would reach saturation at 0.02 M of concentration and it was measured as the concentration increased, the thicknesses of the films increased from the 452 nm to the 798 nm. The well-crystallized film was observed to be at 0.01 M of concentration. It was also found that the band gap increased at low concentrations and surface morphology of the films did not change much with concentration.
PubDate: 2017-03-11

• Effect of temperature on the morphology of ZnO nanoparticles: a
comparative study

• Abstract: The present study reports the comparative analysis for the synthesis of zinc oxide nano particles by precipitation techniques using different zinc precursors. The synthesized nano particles were characterized by X-ray diffractometry (XRD), energy dispersive X-ray analysis and scanning electron microscopy (SEM) analysis for their sizes, shapes and arrangement. SEM has been studied for the samples before as well as after calcination to know the effect of temperature on structural behaviours. The XRD pattern shows the purity of synthesized zinc oxide nano particles and using Debye–Scherrer equation, the average crystal size of synthesized nanoparticles was calculated. The results have been discussed in the light of variation of morphological structures of different samples. Apart from this, the band gap energies of the synthesized particles have also been calculated from UV–visible spectrophotometric analysis, which is quite appreciable with the reported results.
PubDate: 2017-03-11

• Sonochemical synthesis of novel magnesium 1,2,4-triazole-1-carbodithioate
nanoparticles as antifungals

• Abstract: Novel magnesium 1,2,4-triazole-1-carbodithioates were sonochemically synthesized as water-dispersable nanoparticles owing to their water insolubility. The two-step reaction protocol was followed to synthesize the novel triazole ligand system for complexation with magnesium metal due to its low biological toxicity. Different concentrations of Poly Vinyl Pyrrolidine were used to stabilize and standardise the size of nanoparticles, which were characterised by TEM analysis. UV–Visible and infrared spectroscopies were used to analyse the metal ligand interaction, and CHNS analysis was used to propose the structure of the metal complex. The spore germination inhibition technique was used to evaluate the antifungal potential of synthesized nano-complexes against two phytopathogenic test fungi viz. A. alternata and F. moniliforme. The nanoparticles had inflicted moderate in vitro inhibition of fungal growth, which was comparable to standard fungicide Indofil M-45. The in silico toxicity of the compounds was made using the Toxtree analysis software that indicated the compounds belong to class III group of toxicity, which was same as that of commercial standards of DTC.
PubDate: 2017-03-11

• Preparation and properties of polystyrene incorporated with gold and
silver nanoparticles for optoelectronic applications

• Abstract: In this paper, methyl-orange-doped polystyrene (PS) microspheres covered with gold and silver nanoparticles (NPs) have been synthesized. The optical and structural properties of the porous polystyrene films before and after incorporation of Au and Ag nanoparticles were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM), Fourier transformation infrared spectrophotometer (FT-IR), and UV–Vis spectrophotometer. The optical data showed that the optical energy gap of PS film was increased from 2 to 3.4 eV and to 3.5 eV after being filled with Ag and Au nanoparticles, respectively. The electrical and photoresponse properties of Ag–PS/p-Si and Au–PS/p-Si heterojunctions were studied. The rectification characteristics of the junction were improved after nanoparticle incorporation. The photoresponse results confirm the presence of two peaks of response located at 450 and 900 nm. The Au–PS/Si heterojunction gave the best photosensitivity.
PubDate: 2017-03-02

• Self-assembled nanotubes from single fluorescent amino acid

• Abstract: Self-assembly of biomolecules has gained increasing attention as it generates various supramolecular structural assemblies having potential applications principally in biomedical sciences. Here, we show that amino acid like tryptophan or tyrosine readily aggregates as nanotubes via a simple self-assembly process. These were characterized by FTIR, scanning electron microscopy, and by fluorescence microscopy. Nanotubes prepared from tryptophan are having ~200 nm inner diameter and those from tyrosine are having the same around ~50 nm diameter.
PubDate: 2017-03-01

• Nanoparticle targeting of Gram-positive and Gram-negative bacteria for
magnetic-based separations of bacterial pathogens

• Abstract: Antimicrobial resistance is a healthcare problem of increasing significance, and there is increasing interest in developing new tools to address bacterial infections. Bacteria-targeting nanoparticles hold promise to improve drug efficacy, compliance, and safety. In addition, nanoparticles can also be used for novel applications, such as bacterial imaging or bioseperations. We here present the use of a scalable block-copolymer-directed self-assembly process, Flash NanoPrecipitation, to form zinc(II)-bis(dipicolylamine) modified nanoparticles that bind to both Gram-positive and Gram-negative bacteria with specificity. Particles have tunable surface ligand densities that change particle avidity and binding efficacy. A variety of materials can be encapsulated into the core of the particles, such as optical dyes or iron oxide colloids, to produce imageable and magnetically active bacterial targeting constructs. As a proof-of-concept, these particles are used to bind and separate bacteria from solution in a magnetic column. Magnetic manipulation and separation would translate to a platform for pathogen identification or removal. These magnetic and targeted nanoparticles enable new methods to address bacterial infections.
PubDate: 2017-02-24

• A new approach for orientation-controlled growth of CNTs: an in-depth
analysis on the role of oxygen plasma treatment to catalyst

• Abstract: In this paper, a novel and easy technique is proposed for orientation controlled growth of MWNTs. The results indicate that when CNT growth was carried over the substrate, not treated with plasma, horizontal network of MWNTs was formed. Plasma treatment to the substrate prior to CNTs growth led to formation of vertically aligned MWNTs. An in situ growth as a function of plasma treatment time reveals the mechanism behind this flip process. All experiments were performed under atmospheric pressure. At every step during time-dependent growth process, CNTs were characterized using FESEM, HRTEM, and Raman spectroscopy. Iron sputtered silicon substrate was also investigated to validate the excellent formation of as-grown vertical CNTs and also to analyze the role of oxygen plasma behind the orientation-controlled growth. The as-grown CNTs over the iron sputtered silicon substrate with or without plasma treatment were characterized by FESEM and AFM. The successful orientation-controlled growth of CNTs was achieved.
PubDate: 2017-02-20

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Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
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