Three novel acridine-based thiosemicarbazones were investigated for their corrosion inhibition potentials on mild steel in 1 M HCl using combined electrochemical, DFT and Monte Carlo simulation techniques.
New thiosemicarbazide-linked acridines 3a–c were prepared and investigated as chemosensors for the detection of biologically and environmentally important anions. The compounds 3a–c were found selective for fluoride (F−) with no affinity for other anions, i.e. −OAc, Br−, I−, HSO4−, SO42−, PO43−, ClO3−, ClO4−, CN− and SCN−. Further, upon the gradual addition of a fluoride anion (F−) source (tetrabutylammonium fluoride), a well-defined change in colour of the solution of probes 3a–c was observed. The anion-sensing process was studied in detail via UV–visible absorption, fluorescence and 1H-NMR experiments. Moreover, during the synthesis of acridine probes 3a–c nickel fluoride (NiF2), a rarely explored transition metal fluoride salt, was used as the catalyst. Theoretical studies via density functional theory were also carried out to further investigate the sensing and anion (F−) selectivity pattern of these probes.
In recent years, there have been intensive efforts to establish linearised oscillation results for onedimensional delay, neutral delay and advanced impulsive differential equations. An impressive number of these efforts have yielded fruitful results in many analytical and applied areas. This is particularly obvious in the areas of applied disciplines such as the linear delay impulsive differential equations. However, there still remains a lot more to be explored in this direction, especially, in the area of non-linear autonomous differential equations. In this paper, we are proposing the development of linearised oscillation techniques for some general non-linear autonomous impulsive differential equations with several delays.
Functions of bounded variations form important transition between absolute continuous and singular functions. With Bainov’s introduction of impulsive differential equations having solutions of bounded variation, this class of functions had eventually entered into the theory of differential equations. However, the determination of existence of solutions is still problematic because the solutions of differential equations is usually at least absolute continuous which is disrupted by the solutions of bounded variations. As it is known, if f:[a,bλ]→Rn is of bounded variation then f is the sum of an absolute continuous function fa and a singular function fs where the total variation of fs generates a singular measure τ and fs is absolute continuous with respect to τ. In this paper we prove that a function of bounded variation f has two representations: one is f which was described with an absolute continuous part with respect to the Lebesgue measure λ, while in the other an integral with respect to τ forms the absolute continuous part and t(τ) defines the singular measure. Both representations are obtained as parameter transformation images of an absolute continuous function on total variation domain [a,bν].
A survey of recent studies in neutral impulsive differential equations reveals that most of such works revolve around the quest for oscillatory conditions for linear impulsive differential equations. The development of oscillatory and nonoscillatory criteria for nonlinear impulsive differential equations has so far attracted very little attention. In this paper, we obtain sufficient conditions for the existence of oscillatory and nonoscillatory solutions for nonlinear first order neutral impulsive differential equations with constant delays
The oscillations theory of neutral impulsive differential equations is gradually occupying a central place among the theories of oscillations of impulsive differential equations. This could be due to the fact that neutral impulsive differential equations plays fundamental and significant roles in the present drive to further develop information technology. Indeed, neutral differential equations appear in networks containing lossless transmission lines (as in high-speed computers where the lossless transmission lines are used to interconnect switching circuits). In this paper, we study the behaviour of solutions of a certain class of second-order linear neutral differential equations with impulsive constant jumps. This type of equation in practice is always known to have an unbounded non-oscillatory solution. We, therefore, seek sufficient conditions for which all bounded solutions are oscillatory and provide an example to demonstrate the applicability of the abstract result.
Environmental pollution due to heavy metals ions is becoming a serious threat to human health. In this study, we have synthesized acridine‐thiosemicarbazones‐stabilized silver nanoparticles (AT‐AgNPs) to explore their cation sensing ability and selectivity for detection copper(II)‐ion in aqueous system. Newly synthesized nanoparticle were characterized using various spectroscopic techniques such as ultraviolet–visible, Fourier‐transform infrared (FTIR), atomic force microscopy (AFM) and Zetasizer. The average size of the highly robust AT‐AgNPs was found to be in the range of 70–90 nm. The photophysical potential of AT‐AgNPs was explored using ultraviolet–visible spectroscopy. Addition of copper(II)‐ion induce significant quenching in the absorption intensity of AT‐AgNPs, whereas all other tested metals did not produce any detectable change in the UV‐visible spectrum. Further, the limit of detection (LOD) was determined by employing standard deviation method which is found to be 1 μM with a R2 equal to 0.9931. The synthesized AT‐AgNPs were highly selective for copper(II)‐ion in presence of other interferents like salts, and other metal ions. Moreover, the AT‐AgNPs were effectively and efficiently employed for the same purpose in tap water.
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