A sliding-window approximation-based fractional adaptive strategy for Hammerstein nonlinear ARMAX systems

Nonlinear Dynamics - This paper presents a sliding-window approximation-based fractional least mean square (FLMS) algorithm for parameter estimation of Hammerstein nonlinear autoregressive moving...     

Structural and optical properties of thermally reduced graphene oxide for energy devices

Natural intercalation of the graphite oxide, obtained as a product of Hummer's method, via ultra-sonication of water dispersed graphite oxide has been carried out to obtain graphene oxide(GO) and thermally reduced graphene oxide(RGO).Here we report the effect of metallic nitrate on the oxidation properties of graphite and then formation of metallic oxide(MO) composites with GO and RGO for the first time. We observed a change in the efficiency of the oxidation process as we replaced the conventionally used sodium nitrate with that of nickel nitrate Ni(NO_3)_2, cadmium nitrate Cd(NO_3)_2,and zinc nitrate Zn(NO_3)_2. The structural properties were investigated by x-ray diffraction and observed the successful formation of composite of MO–GO and MO–RGO(M = Zn, Cd, Ni). We sought to study the effect on the oxidation process through optical characterization via UV-Vis spectroscopy and Fourier Transform Infrared(FTIR) spectroscopy.Moreover, Thermo Gravimetric Analysis(TGA) was carried out to confirm 90% weight loss in each process thus proving the reliability of the oxidation cycles. We have found that the nature of the oxidation process of graphite powder and its optical and electrochemical characteristics can be tuned by replacing the sodium nitrate(NaNO_3) by other metallic nitrates as Cd(NO_3)_2, Ni(NO_3)_2, and Zn(NO_3)_2. On the basis of obtained results, the synthesized GO and RGO may be expected as a promising material in antibacterial activity and in electrodes fabrication for energy devices such as solar cell, fuel cell,and super capacitors.     

A new lignan and a new sesquiterpene from Eurotia ceratoides (L.)

A new lignan, rayalinol (1) and a new sesquiterpene kairatene (2) were isolated from Eurotia ceratoides (L.) along with four hitherto unreported syringaresinol, dehydrodiconiferyl aldehyde, dihydrodehydrodiconiferyl alcohol, and dehydrodiconiferyl alcohol and two previously reported constituents ferulic acid and β-sitosterol. The structures of the new constituents were elucidated by extensive spectroscopic means and chemical evidences. Rayalinol is a biogenetically interesting compound with a hitherto unreported 9a homolignane skeleton. Its biosynthetic origin is suggested.     

Kinetic and mechanistic investigation of the oxidation of the antibacterial agent levofloxacin by permanganate in alkaline medium

The kinetics and mechanism of oxidation of levofloxacin (LF) by manganese(VII) in alkaline medium at constant ionic strength was studied spectrophotometrically. The reaction exhibits 2:1 Mn:LF stoichiometry and is first order in permanganate but fractional order in both LF and alkali. Decrease in the dielectric constant of the medium results in a decrease in the rate of reaction. The effects of added products and ionic strength have also been investigated. The main products identified were hydroxylated LF and Mn(VI). A mechanism involving free radicals is proposed. In a composite equilibrium step, levofloxacin binds to MnO₄ ⁻ to form a complex that subsequently decomposes to the products. Investigations of the reaction at different temperatures allowed the determination of the activation parameters with respect to the slow step of the proposed mechanism.     

Iterative methods for solving general quasi-variational inequalities

In this paper, we introduce a new class of variational inequalities, which is called the general quasi-variational inequality. We establish the equivalence among the general quasi variational inequality and implicit fixed point problems and the Wiener–Hopf equations. We use this equivalent formulation to discuss the existence of a solution of the general quasi-variational inequality. This equivalent formulation is used to suggest and analyze some iterative algorithms for solving the general quasi-variational inequality. We also discuss the convergence analysis of these iterative methods. Several special cases are also discussed.     

Variational iteration method for solving twelfth-order boundary-value problems using He’s polynomials

In this paper, we apply the variational iteration method using He’s polynomials (VIMHP) for solving the twelfth-order boundary-value problems. The proposed method is an elegant combination of variational iteration and the homotopy perturbation methods. The suggested algorithm is quite efficient and is practically well suited for use in these problems. The suggested iterative scheme finds the solution without any discretization, linearization, or restrictive assumptions. Several examples are given to verify the reliability and efficiency of the method. The fact that the proposed technique solves nonlinear problems without using Adomian’s polynomials can be considered as a clear advantage of this algorithm over the decomposition method.     

Modified mann iterations for nonexpansive semigroups in Banach space

Let E be a real reflexive Banach space which admits a weakly sequentially continuous duality mapping from E to E^＊, and C be a nonempty closed convex subset of E. Let {T（t） ： t ≥ 0} be a nonexpansive semigroup on C such that F ：=∩t≥0 Fix（T（t）） ≠ 0, and f ： C → C be a fixed contractive mapping. If {αn}, {βn}, {an}, {bn}, {tn} satisfy certain appropriate conditions, then we suggest and analyze the two modified iterative processes as：{yn=αnxn＋（1-αn）T（tn）xn,xn=βnf（xn）＋（1-βn）yn
{u0∈C,vn=anun＋（1-an）T（tn）un,un＋1=bnf（un）＋（1-bn）vn
We prove that the approximate solutions obtained from these methods converge strongly to q ∈∩t≥0 Fix（T（t））, which is a unique solution in F to the following variational inequality：
〈（I-f）q,j（q-u）〉≤0 u∈F Our results extend and improve the corresponding ones of Suzuki [Proc. Amer. Math. Soc., 131, 2133-2136 （2002）], and Kim and XU [Nonlear Analysis, 61, 51-60 （2005）] and Chen and He [Appl. Math. Lett., 20, 751-757 （2007）].     

Electrochemical Sensing of Ascorbic Acid,Hydrogen Peroxide and Glucose by Bimetallic (Fe,Ni)−CNTs Composite Modified Electrode

In this research, bimetallic supported CNT modified electrode ( Fe,Ni/CNTs/GCE) has been developed for sensitive, stable and highly elctroactive sensing of glucose, ascorbic acid and hydrogen peroxide. Transition metals such as Iron (Fe) and Nickel (Ni) offer high electrical and thermal conductance, high active surface‐to‐volume ratio and presence of d‐band electrons gives enhanced electrocatalytic behavior. While, CNTs provide high surface area, stability and excellent conductivity. Synthesized material is characterized by SEM, EDS, XRD and FTIR to access morphology, elemental composition and structure. This unique combination is employed for the electrochemical sensing of ascorbic acid, glucose and hydrogen peroxide and different experimental parameters are optimized. Fe,Ni/CNTs/GCE shows good sensing efficiency at pH 7.4 which is ideally suitable for variety of analytes. The modified electrode also show good reproducibility and sensitivity under optimized conditions and can be reused upto 30 cycles without compromising the efficiency. With good linearity, reproducibility and limit of detection, this material possess significant potential as non‐enzymatic biosensor for variety of analytes.     

Complex formation study of antimony trichloride in sodium tetrachloroferrate (III) with excess sodium chloride and determination of thermodynamic parameters by gas chromatography

Summary The retention of SbCl₃ on NaFeCl₄ melt containing excess NaCl is presented. Evidence of definite complex formation is also given. From the retention data, activity coefficients, free energies of solution of SbCl₃ in the melt and corresponding entropies of solution and mixing have been calculated. The data for SbCl₃–NaFeCl₄ and SbCl₃–KFeCl₄ systems have been compared.A part of this work was carried out at Manchester College, North Manchester, Indiana 46962, U. S. A.     

An inimitable and ecological pleasant technique for the assessment of trace amount of copper (II) in tangible samples with new complexing reagent

A simple and rapid spectrophotometric technique has been designed for the trace copper analysis employing 1-(2-Thiazolylazo)-2-naphthol (TAN) reagent in aqueous micellar solution of cetyl trimethylammonium bromide (CTAB) as a surfactant. Copper complexed with 1-(2-Thiazolylazo)-2-naphthol to form bis[1-(2-Thiazolylazo)-2-naphthol]copper. The present spectrophotometric technique was very important since the micellar system was used in place of the toxic, high cost and time-consuming solvent extraction steps. The technique showed an enhanced detection efficiency, specificity, and molar absorptivity. It was found that the molar absorption coefficient and sensitivity of Sandel were ε 2.45 × 10⁴ L mol^?1cm^?1 and 2.6 ngcm^?2 at λ_max 578.4 nm. A linear calibration plot in the range 0.12–5.0 μg mL^?1 was obtained; a stoichiometric metal ligand ratio [M:L] of 1:2 was found for the formation of Cu-[TAN]₂. The complex was formed at pH 9.5 and was stable up to 24 h. The proposed technique has been employed to study copper from different alloys, biological, environmental and pharmaceutical samples.