Modified Eu3+ doped Y2O3 Nanoparticles as Turn-on Fluorescence Sensor for Sensitive Determination of Methamphetamine

Journal of Analytical Chemistry - In this article, a new spectrofluorometric method was developed for the determination of methamphetamine based on a turn-on luminescence response of captopril...     

Dispersive correction for the second- and the third-order nonlinear terms of the electrical energy density for a light-dielectric system

Optical and Quantum Electronics - Classification of hyperspectral image (HSI) is widely used for the study of remotely sensed images. Convolutional Neural Networks (CNNs) are one of the most...     

Spacecraft formation flying in the port-Hamiltonian framework

The problem of controlling the relative position and velocity in multi-spacecraft formation flying in the planetary orbits is an enabling technology for current and future research. This paper proposes a family of tracking controllers for different dynamics of Spacecraft Formation Flying (SFF) in the framework of port-Hamiltonian (pH) systems through application of timed Interconnection and Damping Assignment Passivity-Based Control (IDA-PBC). The leader–multi-follower architecture is used to address this problem. In this regard, first we model the spacecraft motion in the pH framework in the Earth Centered Inertial frame and then transform it to the Hill frame which is a special local coordinate system. By this technique, we may present a unified structure which encompasses linear/nonlinear dynamics, with/without perturbation. Then, using the timed IDA-PBC method and the contraction analysis, a new method for controlling a family of SFF dynamics is developed. The numerical simulations show the efficiency of the approach in two different cases of missions.

     

The convex hull property and topology of hypersurfaces with nonnegative curvature

We prove that, in Euclidean space, any nonnegatively curved, compact, smoothly immersed hypersurface lies outside the convex hull of its boundary, provided the boundary satisfies certain required conditions. This gives a convex hull property, dual to the classical one for surfaces with nonpositive curvature. A version of this result in the nonsmooth category is obtained as well. We show that our boundary conditions determine the topology of the surface up to at most two choices. The proof is based on uniform estimates for radii of convexity of these surfaces under a clipping procedure, a noncollapsing convergence theorem, and a gluing procedure.     

A tabu search heuristic for solving the CLSP with backlogging and set-up carry-over

In this paper, the multi-item, single-level, capacitated, dynamic lot sizing problem with set-up carry-over and backlogging, abbreviated to CLSP⁺, is considered. The problem is formulated as a mixed integer programming problem. A heuristic method consisting of four elements: (1) a demand shifting rule, (2) lot size determination rules, (3) checking feasibility conditions and (4) set-up carry-over determination, provides us with an initial feasible solution. The resulting feasible solution is improved by adopting the corresponding set-up and set-up carry-over schedule and re-optimizing it by solving a minimum-cost network flow problem. Then the improved solution is used as a starting solution for a tabu search procedure, with the value of moves assessed using the same minimum-cost network problem. Computational results on randomly generated problems show that the algorithm, which is coded in C++, is able to provide optimal solutions or solutions extremely close to optimal. The computational efficiency makes it possible to solve reasonably large problem instances routinely on a personal computer.     

Parametric study of the flow and temperature fields in an inductively coupled r.f. plasma torch

A theoretical investigation of the effect of different parameters on the flow and the temperature fields in a radiofrequency inductively coupled plasma is carried out. The parameters studied are: central injection gas flow rate, total gas flow rate, input power, and the type of plasma gas. The results obtained for argon and nitrogen plasmas at atmospheric pressure indicate that the flow and the temperature fields in the coil region, as well as the heat flux to the wall of the plasma confinement tube, are considerably altered by the changes in the torch operating conditions.     

Spectrophotometric Study of the Complexation of Some Lanthanide (III) Ions with a Series of 18-Crowns-6 in DMSO Solution Using Murexide as a Metallochromic Indicator

The complexation of La(III), Ce(III), Pr(III) and Er(III) with 18-crown-6(18C6), dibenzo-18-crown-6 (DB18C6), dicyclohexano-18-crown-6 (DCY18C6) anddibenzopyridino-18-crown-6 (DBPY18C6) has been studied in dimethylsulfoxide(DMSO) by means of a competitive spectrophotometric method using murexide asa metal ion indicator. The formation constants of the 1 : 1 complexeswere found tovary in the order La(III) > Ce(III) > Pr(III) > Er(III). It was foundthat the structure influences the formation and stability of the resultingcomplexes. The effects ofvarious parameters on complexation are discussed. The order of the stabilityconstants of each lanthanide ion with these macrocycles are18C6 > DC18C6 > DB18C6 > DBPY18C6.     

Stripping voltammetry of thorium based on adsorptive accumulation

A sensitive stripping voltammetric procedure for quantifying thorium is described. The chelate of thorium with the azo dye Mordant Blue 9 is adsorbed on the hanging mercury drop electrode, and the reduction current of the accumulated chelate is measured during a negative-going potential scan. Cyclic voltammetry is used to characterize the interfacial and redox behaviors. The effects of pH, dye concentration and accumulation potential are discussed. The detection limit is 4 × 10^?10 M (4-min accumulation), a linear current-concentration relationship is observed up to 1.3 × 10^?7 M, and the relative standard deviation (at the 6 × 10^?8 M level) is 3.1%. Possible interferences by trace metals and organic surfactants are investigated. Simultaneous quantitation of thorium and nickel is illustrated.     

A study of peroxyoxalate-chemiluminescence of acriflavine

The chemiluminescence arising from the reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO) with hydrogen peroxide in the presence of acriflavine has been studied. The relationship between the chemiluminescence intensity and concentrations of TCPO, H2O2, acriflavine and the base sodium salicylate are reported. The kinetic parameters for the peroxyoxalate-chemiluminescence (PO-CL) of acriflavine were evaluated from the computer fitting of the corresponding chemiluminescence intensity-time plots.     

A selective modified carbon paste electrode for determination of cyanide using tetra-3,4-pyridinoporphyrazinatocobalt(II)

A chemically modified carbon paste electrode with 3,4-tetra pyridinoporphirazinatocobalt(II) (Co(3,4 tppa) was applied to the determination of free cyanide ion. The electrode has a linear range between 1.5 × 10⁻⁵ M and 1.0 × 10⁻² M with a Nernstian slope of 60 ± 1.5 mV/decade and its detection limit is 9 × 10⁻⁶ M. The response time of electrode is 5 min. The proposed electrode was applied successfully for the determination of cyanide in commercially available spring water. Some anions, such as SCN⁻, I⁻, Cl⁻, Br⁻ and oxalate that are usually serious interfering species for most of cyanide selective electrodes, did not have any interfering effect for this proposed electrode.