Dual Fluorometric Detection of Fe3+ and Hg2+ Ions in an Aqueous Medium Using Carbon Quantum Dots as a “Turn-off” Fluorescence Sensor

The present study aimed to develop a carbon dots-based fluorescence (FL) sensor that can detect more than one pollutant simultaneously in the same aqueous solution. The carbon dots-based FL sensor has been prepared by employing a facile hydrothermal method using citric acid and ethylenediamine as precursors. The as-synthesized CDs displayed excellent hydrophilicity, good photostability and blue fluorescence under UV light. They have been used as an efficient “turn-off” FL sensor for dual sensing of Fe³⁺ and Hg²⁺ ions in an aqueous medium with high sensitivity and selectivity through a static quenching mechanism. The lowest limit of detection (LOD) for Fe³⁺ and Hg²⁺ ions was found to be 0.406 µM and 0.934 µM, respectively over the concentration range of 0-50 µM. Therefore, the present work provides an effective strategy to monitor the concentration of Fe³⁺ and Hg²⁺ ions simultaneously in an aqueous medium using environment-friendly CDs.

Graphical Abstract

     

Zirconium(IV) Thorium(IV) and Dioxouranium(VI) Complexes of Salicylidene o-Aminobenzothiol

Salicylidene-o-aminobenzothiol and its 5-chloro and 5-bromo derivatives, dibasic tridentate Schiff bases, dervied from the condensation of o-aminothiol and Salicylaldehyde, 5-chloro salicylaldehyde and 5-bromo salicylaldehyde, were used for coordination with Zr(IV), Th(IV) and UO₂(VI) metal inos. The I:I (metal-ligand) stoichiometry of these complexes is shown by elemental analysis and conductometric titrations. Molecular structure of these complexes are proved by Infra-red spectroscopy and thermogravimetric analysis. Magnetic susceptibility measurements of Zr(IV), Th(IV) and UO₂(VI) complexes show their diamagnetic and octahedral geometry. Results show that all the complexes have solvent molecules in coordination with metal ion.     

A Facile Method for Detection and Speciation of Inorganic Selenium with Ion Chromatography

Chromatographia - In this work, we present a new method for the determination and speciation of selenium in water with ion chromatography (IC) using a conductometric detector. Chromatographic...     

Effect of Rotation on Rayleigh—Lamb Waves in an Isotropic Generalized Thermoelastic Diffusive Plate

The present investigation is aimed at studying the effect of rotation on propagation of Rayleigh—Lamb waves in a homogeneous isotropic thermoelastic diffusive plate of finite width in the framework of different theories of thermoelasticity, including the Coriolis and centrifugal forces. The medium is subjected to stress-free, thermally insulated, isothermal, and chemical potential boundary conditions and is rotating about an axis perpendicular to its plane. Secular equations corresponding to the symmetric and skew-symmetric modes of the plate are derived. Phase velocities and attenuation coefficients of various possible modes of wave propagation are computed from the secular equations. Amplitudes of displacements, temperature, and concentration for symmetric and skew-symmetric modes of plate vibrations are computed numerically. The computed results are presented graphically.     

Interaction of nucleosides with antitumoural agents : 9-hydroxy-N-2-methylellipticinium acetate and 9-hydroxy-N-2-methylolivacinium acetate

Reaction of 9-hydroxypyrido[4,3-b] carbazole derivatives under oxidative conditions (biochemical : HRP/H₂O₂, chemical : Cu₂Cl₂/Pyridine/O₂) has been found to furnish regio-and stereo-selectively a ketalic linkage at the 10-position of this type of compound. Detailed structure elucidation of the products has been given. The regio- and stereo-specificity of the reaction has been demonstrated to be due to π-π stacking between the ribonucleosidic base and the 9-hydroxypyridocarbazole nucleus. Acid Catalysed isomerisation of $\text{11}$ to $\text{29}$ has also been studied in detail. In the light of these results, it is proposed that besides the “classical” intercalation into DNA, this type of compound can also react with RNA. This reactivity could explain, at least partially, the pharmacological (antitumour) activity of these compounds and should lead to a promising field of research in molecular biology.     

Nucleophilic addition of aliphatic amino acids to N-2-methyl-9-hydroxy-ellipticinium acetate under peroxidase-catalysed oxidative conditions : a reinvestigation and structural revision of the adducts

A reinvestigation of the adducts resulting from a peroxidase-catalysed reaction of $\text{N}$-2-methyl-9-hydroxyellipticinium acetate 1 with some aliphatic amino acids led to their structural revision from 3 to 4.     

Efficient derivative-free variants of Hansen-Patrick’s family with memory for solving nonlinear equations

In this paper, we present a new tri-parametric derivative-free family of Hansen-Patrick type methods for solving nonlinear equations numerically. The proposed family requires only three functional evaluations to achieve optimal fourth order of convergence. In addition, acceleration of convergence speed is attained by suitable variation of free parameters in each iterative step. The self-accelerating parameters are estimated from the current and previous iteration. These self-accelerating parameters are calculated using Newton’s interpolation polynomials of third and fourth degrees. Consequently, the R-order of convergence is increased from 4 to 7, without any additional functional evaluation. Furthermore, the most striking feature of this contribution is that the proposed schemes can also determine the complex zeros without having to start from a complex initial guess as would be necessary with other methods. Numerical experiments and the comparison of the existing robust methods are included to confirm the theoretical results and high computational efficiency.     

Viscosity and Diffusion Effects at the Boundary Surface of Viscous Fluid and Thermoelastic Diffusive Solid Medium

This paper concentrates on the wave motion at the interface of viscous compressible fluid half-space and homogeneous isotropic, generalized thermoelastic diffusive half-space. The wave solutions in both the fluid and thermoelastic diffusive half-spaces have been investigated; and the complex dispersion equation of leaky Rayleigh wave motion have been derived. The phase velocity and attenuation coefficient of leaky Rayleigh waves have been computed from the complex dispersion equation by using the Muller's method. The amplitudes of displacements, temperature change and concentration have been obtained. The effects of viscosity and diffusion on phase velocity and attenuation coefficient of leaky Rayleigh waves motion for different theories of thermoelastic diffusion have been depicted graphically. The magnitude of heat and mass diffusion flux vectors for different theories of thermoelastic diffusion have also been computed and represented graphically.     

Regio- and stereoselective alkylation at the 3′-terminal end of ribonucleotides by N-2-methyl-9-hydroxyellipticinium acetate : an antitumor agent

The regio- and stereoselective alkylation at the 3′-terminal end of ribonucleotides by N-2-methyl-9-hydroxyellipticinium acetate under oxidative conditions is reported.     

Preparation and Characterization of Dioxotungsten (VI) Complexes of Schiff Bases Derived from Salicylaldehydes and O-Aminothiophenol

Several dioxotungsten(VI) complexes of the type WO₂L and WO₂L.X (where LH₂ = Schiff base derived from o-aminothiophenol and salcylaldehyde, 5-chlorosalicylaldehyde, 5-bromosalicylaldehyde, and X = dimethyl formamide, dimethyl sulfoxide or pyridine) have been prepared and characterized by elemental analysis, electrical conductance, magnetic and spectral measurements. These complexes are non-electrolyte, diamagnetic, six-coordinated and possess an octahedral geometry.