A non-enzymatic sensor for hydrogen peroxide based on polyaniline, multiwalled carbon nanotubes and gold nanoparticles modified Au electrode

We describe the construction of a polyaniline (PANI), multiwalled carbon nanotubes (MWCNTs) and gold nanoparticles (AuNPs) modified Au electrode for determination of hydrogen peroxide without using peroxidase (HRP). The AuNPs/MWCNT/PANI composite film deposited on Au electrode was characterized by Scanning Electron Microscopy (SEM) and electrochemical methods. Cyclic voltammetric (CV) studies of the electrode at different stages of construction demonstrated that the modified electrode had enhanced electrochemical oxidation of H(2)O(2), which offers a number of attractive features to develop amperometric sensors based on split of H(2)O(2). The amperometric response to H(2)O(2) showed a linear relationship in the range from 3.0 μM to 600.0 μM with a detection limit of 0.3 μM (S/N = 3) and with high sensitivity of 3.3 mA μM(-1). The sensor gave accurate and satisfactory results, when employed for determination of H(2)O(2) in milk and urine.     

Dual-fluorophore ratiometric pH nanosensor with tuneable pKa and extended dynamic range

Ratiometric pH nanosensors with tuneable pK(a) were prepared by entrapping combinations of two pH-sensitive fluorophores (fluorescein isothiocyanate dextran (FITC-D) and Oregon Green(?) dextran (OG-D)) and a reference fluorophore (5-(and-6)-carboxytetramethylrhodamine dextran (TAMRA-D)), in a biocompatible polymer matrix. Dual-fluorophore pH nanosensors permit the measurement of an extended dynamic range, from pH 4.0 to 7.5.     

Large-scale synthesis of ZnO balls made of fluffy thin nanosheets by simple solution process: structural, optical and photocatalytic properties

This paper reports a large-scale synthesis of ZnO balls made of fluffy thin ZnO nanosheets by simple solution process at low-temperature of 65±2°C. The synthesized ZnO structures were characterized in detail in terms of their morphological, structural, optical and photocatalytic properties. The detailed morphological characterizations, done by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), confirmed that the synthesized products are ZnO balls which are made by accumulation of hundreds of thin ZnO nanosheets. Interestingly, it is seen that the nanosheets are arranged in such a special fashion that they made ball-like morphologies. Detailed structural examinations revealed that of as-synthesized ZnO products are well-crystalline and possessing wurtzite hexagonal phase. The optical property, measured by UV-Visible spectroscopy, substantiated good optical properties for as-synthesized ZnO balls. The as-synthesized ZnO balls were utilized as an efficient photocatalysts for the photocatalytic degradation of methylene blue (MB) dye. Almost complete degradation of MB was observed in presence of ZnO balls composed of nanosheets within 70 min under UV-light irradiation. By comparing the photocatalytic performance with commercially available TiO(2)-UV-100, it was observed that the synthesized ZnO balls exhibited superior photocatalytic performance as compared to TiO(2)-UV-100 photocatalyst.     

Study of dielectric properties of single phase Bi1−xCaxFeO3 (x = 0.1, 0.3, 0.5)

A series of Bi_1−xCa_xFeO₃ (x = 0.1, 0.3, 0.5) multiferroic samples have been prepared in order to study the effect of different concentrations of Ca on the crystal structure, and dielectric properties. Structural analysis has been performed using X-ray diffraction (XRD) measurements. Rietveld refined XRD data confirm that all the samples are of single phase, having hexagonal structure with R3c space group. Cell parameters decrease systematically with increase in Ca concentration. Dielectric measurements have been performed in the temperature range of 200–450 K at selected frequencies in the range 100–1100 kHz. A near room temperature ferroelectric anomaly has been observed in all the samples which shift toward lower temperature with increase in doping. Conduction activation energies are calculated and found to decrease with increasing doping.     

Single-shot multiple-delay crossed-beam spectral interferometry for measuring extremely complex pulses

We demonstrate a single-shot measurement technique based on spectral interferometry (SI) for measuring the complete intensity and phase vs. time of extremely complex ultrashort laser pulses. Ordinarily, such a method would require an extremely-high-resolution spectrometer, but, by temporally interleaving many SI measurements, each using a different reference-pulse delay, our method overcomes this need. It involves introducing a transverse time delay into the reference pulse by tilting its pulse front transversely to the spectrometer dispersion plane. The tilted reference pulse then gates the unknown pulse by interfering with it at the image plane of a low-resolution imaging spectrometer, yielding an effective increase in the delay range and spectral resolution—by a factor of 30 in our proof-of-principle implementation. Our device achieved a temporal resolution of ~ 130 fs and a temporal range of 120 ps. This simple device has the potential to measure even longer and more complex pulses.     

Probing the Reactivity and Radical Nature of Oxidized Transition Metal-Thiolate Complexes by Mass Spectrometry

Transition metal thiolate complexes such as [PPN]⁺[RuL₃]^- (PPN?=?bis(triphenylphosphoranylidene) ammonium and L?=?diphenylphosphinobenzenethiolate) are known to undergo addition reactions with unsaturated hydrocarbons via the formation of new C-S bonds in solution upon oxidation. The reaction mechanism is proposed to involve metal-stabilized thiyl radical intermediates, a new type of distonic ions such as [RuL₃]⁺ ion in the case of [PPN]⁺[RuL₃]^-. This study presents the reactivity and structure investigation of [RuL₃]⁺ by mass spectrometry (MS) in conjunction with ion/molecule reactions. The addition reactions of [RuL₃]⁺ with alkenes or methyl ketones in the gas phase are indeed observed, in agreement with the proposed mechanism. Such reactivity is also maintained by several fragment ions of [RuL₃]⁺, indicating the preserved thiyl diradical core structure is responsible for the addition reaction. The thiyl radical nature of [RuL₃]⁺ was further verified by the ion/molecule reaction of [RuL₃]⁺ with dimethyl disulfide, in which the characteristic CH₃S? transfer occurs, both at atmospheric pressure and also at low pressure (~mTorr). These results provide, for the first time, clear mass spectrometric evidence of the radical nature of [RuL₃]⁺ (i.e., the distonic ion structure of [RuL₃]⁺), arising from the oxidation of non-innocent thiolate ligands of the complex [PPN]⁺[RuL₃]^-. Similar thiolate complexes, including ReL₃ and NiL₂, were also examined. Although reactions of oxidized ReL₃ or NiL₂ with CH₃SSCH₃ take place at atmospheric pressure, the corresponding reaction did not occur in vacuum. Consistent with these data, the addition of ethylene was not observed either, indicating lower reactivities of [ReL₃]⁺ and [NiL₂]⁺ in comparison to [RuL₃]⁺.      

Effect of plasma on modal dispersion characteristics of elliptical Bragg waveguide

In this paper, the dispersion characteristics of a plasma filled elliptical Bragg waveguide is investigated. The modal characteristic equations of the proposed Bragg waveguide for both ω > ω_p and ω < ω_p are derived. The effects of plasma frequency, numbers of cladding layers and the eccentricity of elliptical Bragg waveguide on the dispersion characteristics are studied. The analysis shows that the introduction of plasma in the proposed waveguide allows to control the propagation of modes.     

Synthesis of Pyrazole Derivatives Possessing Anticancer Activity: Current Status

Pyrazole is a versatile lead compound to design potent bioactive molecules for drug discovery and development, particularly in cancer therapy. The aim of this review is to present the most recent deeds in the field of synthetic route made for functionalized pyrazole derivatives active against cell proliferation disease. The review article covers the synthesis of 1H-pyrazole, synthesis of N-substituted pyrazoles, synthesis of pyrazolopyrazoles, and synthesis of pyrazoles fused with a naturally occurring moiety. Some of these reported compounds have passed the preclinical or initial-phase clinical trials for their anticancer activity.     

Electrical,structural and thermal studies of carbon nanotubes from natural legume seeds: kala chana

ABSTRACT

Carbon nanotubes (CNTs) are the carbon materials measured at nanoscale level and they are defined in two types according to the number of concentric layers, i.e. single-layer tube is single-walled nanotubes, while multi-layer tube structure is called multi-walled nanotubes. The green method synthesis for the preparation of CNTs begins with the smashing of legume seeds kala chana, and then they form complex with cobalt salt. Desiccation of the complex compound forms cobalt salt and seed protein. The complex is then decomposed at 625 ºC in muffle furnace for 20 min. Purification of the decomposed sample is done through acid wash treatment and dried in vacuum oven. The confirmations of CNTs are done by nuclear magnetic resonance and Fourier transform infrared, which analyzes the denatured protein, reacted to the metal salt. X-Ray diffraction determines the MWNTs with transmission electron microscope (TEM) reports the network structure of CNTs. thermal gravimetric analysis (TGA)–differential thermal analysis (DTA)–thermogravimetric analysis (DTG) tests the amount of sample under thermal treatment. Vibrating sample magnetometer determines the paramagnetic nature of CNTs. CNTs thus prepared can be used in mechanical fields, in solar cells, in electronics fields, etc. because of their multidisciplinary properties. The synthesized CNTs are eco-friendly in nature, prepared by the legume seed natural precursor.