Search

Here, the system of amorphous glassy system, xAgI—(1-x) (0.1CdO—0.3 V2O5—0.4 P2O5—0.2ZnO) with x = 0, 0.05, 0.1, 0.2, 0.3, 0.4 has been developed. The gradual change in the size of various nanocrystallites such as VO2, Zn2V2O7, V6O13, ZnV3O8, and P and the development of new phases of their combinations have been pronounced due to a gradual increase in AgI content. This may lead to possible structural changes of the system under investigation. V–O-V vibration at lower energy may be responsible for weakening the covalent bond, which may be responsible for releasing vanadium ion to contribute more electron/polaron. Correlated barrier hopping (CBH) model has been found to appropriate to predict the hopping conduction paths of charge carriers (or polarons) in pairs via current transfer between localized sites at the Fermi level. By incorporation of more and more AgI content in the composition, more bridging oxygen is expected to be formed in the composition and a strong covalent bonding between Ag+ and O−2 may play dominating role for Ag+ transport over polaron hopping. Double activation energy corresponding to DC conductivity in a wide range of temperature may be considered as the signature of mixed conduction process in the present system. Estimated values of frequency exponent (n) may be highlighted to validate this mixed conduction process. Percolation type of motion of polaron may be predicted from the higher values of n for the as-prepared samples with higher AgI content. Similarly, three-dimensional Ag+ motion may be the dominating charge carriers for the samples with higher AgI content as evidenced from the moderate values of n. A schematic conduction model has been proposed to explain the nature of electrical conductivity in the present system. [ABSTRACT FROM AUTHOR]

Graphene has intriguing electrical, mechanical, thermal and biological properties that are being investigated for use in composites, modern electronics, membranes, and in the industry. Also, graphene has huge biological applications. Hydroxypropyl methylcellulose (HPMC) is a widely used bio-polymer effective for various biomedical applications. As a filler in this polymer matrix, graphene oxide (GO), reduced graphene oxide (RGO) and silver (Ag) nanoparticles (NPs) can be used to improve various properties of the matrix. They are also beneficial for bio-applications like drug delivery, the production of reactive oxygen species (ROS) and the antimicrobial properties of nanocomposite films. Here we synthesize a series of polymer nanocomposites taking GO, RGO and Ag NPs as a filler by the solution mixing method and explore the comparative biological application of such composites. We choose Ag NPs as it has the superior potential for multiple drug resistance. X-ray diffraction, Fourier-transform infrared and scanning electron microscope studies are used to describe how nanocomposites are formed. Energy-dispersive X-ray and dynamic mechanical analyzer analyses were also done to check elemental percentage in nanocomposite films and mechanical properties, respectively. To check several fruitful applications, antimicrobial properties, ROS generation and in-vitro drug release study of nanocomposite films with the loading of Ketorolac Tromethamine were also performed. [ABSTRACT FROM AUTHOR]

Here, development of some Ag2S mixed chalcogenide glassy systems has been discussed in the light of DC conductivity model and variable range hopping model. X-ray diffraction (XRD) pattern has been collected to explore microstructure of them. Various nanophases such as Ag2Se and GeSe2 have been pointed out from XRD studies. Defects have been identified in the form of dislocation, and their roles in the electrical transport properties have been established. FE-SEM micrographs exhibit their amorphous nature with distributed sharper crystal-like structure. Optical phonon frequency may cause to enhance the structural vibrations by means of increasing DC electrical conductivity. Significant enhancement of density of states near Fermi level at low and high temperatures have been explained. Present glassy structure is expected to expand to reduce the scattering cross-section for getting higher values of N(EF) at higher temperature up to a great extent. [ABSTRACT FROM AUTHOR]

Co-RGO nanocomposites are known to show interesting properties suitable for various applications. However, its use in the vital field of plasmonic nanocomposites is restricted as Co nanoparticles have high damping and dielectric loss. In this work, we have demonstrated a simple synthetic way to produce water-dispersible shape variant Co-reduced graphene oxide (RGO) hybrid nanocomposites, which can overcome those barriers and delineate two plasmonic peaks. Prepared multifunctional optical materials show both UV and visible range of plasmonic responses of Co NPs. While the single domain Co NPs show spin-up channel based sharp plasmonic peak in the UV range, the larger particles introduce shape-dependent enhancement of the excitation independent blue photoluminescence of graphene oxide (GO). Usually, due to their different size regime, it is not possible to see both UV and visible range plasmonic responses of Co NPs simultaneously. The variation of the Co particle size was deliberate to achieve multifunctionality. Shape-induced enhancement in the PL spectrum and decoration of plasmonic metal NPs are achieved. TEM micrographs of hybrids confirm the decoration of different shapes of Co nanoparticles on RGO sheets. The size distribution of the nanoparticles in the composites was quantified using two complementary techniques; SAXS/SANS and TEM. Scattering revealed the alteration of RGO agglomeration with the incorporation of differently shaped nanoparticles. Prepared hybrid nanocomposite having both the responses could be promising in magnetoplasmonics, GMR- and doping-based optoelectronics. [ABSTRACT FROM AUTHOR]

Nanoclay-based drug delivery vehicle has acquired immense recognition owing to its unique physico-chemical properties. In this study, tetracycline hydrochloride (TCH) drug was intercalated into the interlayer gallery of montmorillonite (Mt) clay by a cation exchange process. The intercalated nanocomposites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray and thermogravimetric study. It was evident from the characterization that TCH drug was successfully intercalated into the interlayer gallery of Mt clay. These clay-based formulations exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria on analyses via zone inhibition methods. An in-vitro drug release study was performed in phosphate buffer at physiological temperature and interestingly it exhibited sustained and controlled release of TCH from the nanocomposites, after an initial burst-out effect. Overall, this study showed that these nanocomposite materials have immense potential for use in controlled drug delivery strategies for antibacterial treatment. [ABSTRACT FROM AUTHOR]

This article investigates the possibility of using electrical impedance spectroscopy (EIS) technique for detection and quantification of metanil yellow (MY) in turmeric powder. The observation is supported by ultraviolet–visible (UV–Vis) absorption spectroscopy and Fourier transform mid infrared (FT-MIR) spectroscopy. Variation of electrical parameters like capacitance, impedance, conductance, and current–voltage (I–V) characteristics for pure as well as adulterated turmeric are analyzed. System capacitance, conductance, and current are observed to increase, whereas the impedance values have been found to decrease with increase in MY content. Also, UV–Vis and FT-MIR spectroscopic measurements suggest the increase of absorbance with gradual increment of MY in the solution. Electrical and optical results have been physically corroborated with respect to the system internal energy. This study sought to provide a deterministic approach towards developing an EIS-based adulterant sensor for simple, rapid, economical, and precise quantification of controlled percentage weights of MY in pure turmeric powder. [ABSTRACT FROM AUTHOR]

Background: Bacteria endogenously residing within the plant tissues have attracted significant attention for production of biopolyester, polyhydroxyalkanoates (PHAs). Bacillus cereus RCL 02 (MCC 3436), a leaf endophyte of oleaginous plant Ricinus communis L. accumulates 81% poly(3-hydroxybutyrate) [P(3HB)] of its cell dry biomass when grown in mineral salts (MS) medium.Methods: The copolymer production efficiency of B. cereus RCL 02 was evaluated in valeric acid supplemented MS medium under biphasic cultivation condition. The copolymer so produced has been compared with the P(3HB) isolated from RCL 02 in terms of thermal, mechanical and chemical properties.Results: Valeric acid supplementation as co-substrate in the medium has led to the production of copolymer of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) [P(3HB-co-3HV)] with 14.6 mol% 3HV. The identity of the polymers has been confirmed by X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopic studies. Thermogravimetric analysis (TGA) revealed that P(3HB) and P(3HB-co-3HV) films degraded at 278.66°C and 273.49°C, respectively. The P(3HB-co-3HV) showed lower melting temperature (165.03°C) compared to P (3HB) (170.74°C) according to differential scanning calorimetry (DSC). Incorporation of 3HV monomers decreased the tensile strength (21.52 MPa), tensile modulus (0.93 GPa), storage modulus (E′) (0.99 GPa) and increased % elongation at break (12.2%) of the copolyester. However, P(3HB) showed better barrier properties with lower water vapor transmission rate (WVTR) of 0.55 g-mil/100 in2/24 h.Conclusion: These findings emphasized exploration of endophytic bacterial strain (RCL 02) to produce biodegradable polyesters which might have significant potential for industrial application. [ABSTRACT FROM AUTHOR]

In recent times, biosynthetic approaches toward the synthesis of nanoparticles have been shown to have several advantages over physical and chemical methods. Here, we report the extracellular mycosynthesis of γ-FeO nanoparticles by Alternaria alternata. The fungal biomass when exposed to aqueous iron(III) chloride solution led to the formation of highly stable γ-FeO nanoparticles extracellularly. The influence of these biosynthesized γ-FeO nanoparticles on the properties of hydroxyl propyl methyl cellulose was also investigated. Characterization of the biosynthesized γ-FeO nanoparticles and HPMC-γ-FeO nanocomposite films were done by the different types of spectral and electron microscopic analysis. The size of the γ-FeO nanoparticles ranges from 75 to 650 nm. The mechanical effect of the agglomerated γ-FeO nanoparticles into the HPMC polymer matrix was also investigated. [ABSTRACT FROM AUTHOR]

Graphene and its related materials are important areas of research in recent years owing to their unique properties. The wide-range industrial application of graphene-related compounds has led to the development of novel and simple methods for the synthesis of graphene. In this paper, an environmentally friendly green synthesis for the partial reduction of graphene oxide (GO) to reduced GO (RGO) in a cost-effective single-step mechanism was reported. The method completely avoids the use of toxic and environmentally harmful reducing agents commonly used in the chemical reduction of GO to obtain RGO. The reduction of GO was carried out using aqueous leaf extracts of Paederia foetide L. The prepared GO and green RGO were characterized by ultraviolet-visible, Raman and Fourier transform infra-red spectroscopic analysis which showed a clear indication of the partial removal of oxygen-containing groups from the GO and the formation of RGO. The morphology of the green RGO was characterized by transmission electron and scanning electron microscopy. Dynamic light scattering was used for zeta potential measurement and correlated with the morphology of the sheets. Electrical conductivity was also measured to check the extent of reduction of GO to RGO. [ABSTRACT FROM AUTHOR]

Alkyne-terminated poly( d,l-lactide-co-glycolide) (PLGA) has been synthesized via ROP at room temperature. Amphiphilic PLGA- b-poly( N-vinylpyrrolidone) (PNVP) block copolymers have been synthesized via alkyne-azide click reaction of it with azide-terminated PNVPs prepared by RAFT polymerization of NVP using an azide-terminated RAFT agent. H NMR and gel permeation chromatography (GPC) confirmed the formation of block copolymers. Self-assembly of these block copolymers was confirmed by fluorescence study using pyrene as a probe and supported by H NMR, DLS and TEM studies. Hydrophobic drug doxorubicin was successfully encapsulated at the micellar core of PLGA- b-PNVP with drug-loading content (DLC) and drug-loading efficiency (DLE) of 10.8 and 43.2 %, respectively. Sustained drug release of these drug-loaded micelles was observed at both pH of 6.4 and 7.4. Faster drug release was observed at pH 6.4. Such PLGA- b-PNVP amphiphilic block copolymer may find extensive application in sustained drug delivery, specifically in antitumor drug delivery. [ABSTRACT FROM AUTHOR]

We have proposed a facile green technique for synthesizing silver nanoparticles-based nanofluids at high temperature and pressure using low molecular weight lactulose solution, which is playing the role of a reducing as well as stabilizing agent. The particle/crystallite sizes, morphology, crystallinity of the nanoparticles are characterized using spectroscopic, microscopic, and diffraction techniques. Since the properties of nanofluids are attractive for technological applications, the investigation of their thermal and electrical conductivities is also immensely important. The material shows a significant enhancement of both thermal and electrical conductivities in comparison to the base fluid due to high surface area, enhanced Brownian motion and layering at the liquid-solid interface of the nanofluids. Moreover, these nanofluids offer excellent antimicrobial activities to different gram class bacteria. [ABSTRACT FROM AUTHOR]

The secrets gleaned from nature have led to the development of biomimetic approaches for the growth of advanced nanomaterials. Biological methods for nanoparticle synthesis using microorganisms, enzymes, and plants or plant extracts have been suggested as possible ecofriendly alternatives to chemical and physical methods. Here, we report extracellular mycosynthesis of ZnO-NPs by Alternaria alternata (Fr.) Keissl (1912). On treating zinc sulfate solution with fungal culture filtrate, rapid reduction of ZnSO was observed leading to the formation of highly stable ZnO-NPs in the solution and up-to-date literature survey showed this was the first report of biosynthesis of ZnO-NPs using this fungus. The particles thereby obtained were characterized by different analytical techniques. EDX-spectrum revealed the presence of zinc and oxygen in the nanoparticles. FTIR spectroscopy confirmed the presence of a protein shell outside the nanoparticles which in turn also support their stabilization. DLS and TEM analysis of the ZnO-NPs indicated that they ranged in size from 45 to 150 nm with average size of 75 ± 5 nm. But potential negative impacts of nanomaterials are sometimes overlooked during the discovery phase of research. Therefore, in the present study, bio-safety of mycosynthesized ZnO-NPs were evaluated by using cytotoxicity and genotoxicity assays in human lymphocyte cells, in vitro. Cytotoxicity studied as function of membrane integrity and mitochondrial dehydrogenase activity revealed significant ( P < 0.05) toxicity at treatment concentration of 500 μg/ml and above. Additionally, DNA damaging potential was also studied using comet assay. The results revealed significant genotoxicity at the highest concentration (1,000 μg/ml). [ABSTRACT FROM AUTHOR]

The development of an eco-friendly and reliable process for the synthesis of gold nanomaterials (AuNPs) using microorganisms is gaining importance in the field of nanotechnology. In the present study, AuNPs have been synthesized by bio-reduction of chloroauric acid (HAuCl) using the fungal culture filtrate (FCF) of Alternaria alternata. The synthesis of the AuNPs was monitored by UV-visible spectroscopy. The particles thereby obtained were characterized by UV, dynamic light scattering (DLS), X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM) and transmission electron microscopy (TEM). Energy-dispersive X-ray study revealed the presence of gold in the nanoparticles. Fourier transform infrared spectroscopy confirmed the presence of a protein shell outside the nanoparticles which in turn also support their stabilization. Treatment of the fungal culture filtrate with aqueous Au ions produced AuNPs with an average particle size of 12 ± 5 nm. This proposed mechanistic principal might serve as a set of design rule for the synthesis of nanostructures with desired architecture and can be amenable for the large scale commercial production and technical applications. [ABSTRACT FROM AUTHOR]

Change in poly (vinyl alcohol) (PVA) molecular weight has been found to affect nanosilica phase morphology in PVA-ex-situ silica aqueous gel which in turn influences shear viscometric parameters such as near-zero shear viscosity, pseudoplastic index, thixotropic index and net viscosity drop at various levels of nanosilica contents. About 25 °C rise in temperature does not produce any serious changes in these parameters from that studied at room temperature. [ABSTRACT FROM AUTHOR]