Parallel vector analysis based soft resolution of spectral data from pH‐metric titration using symmetry constraint

In this study, a soft method is proposed to calculate concentration and spectral profiles for the two‐way spectral data from dissociation equilibria of polyprotic acids (H_nA). This method has four main distinct steps: (i) a fixed size moving window evolving factor analysis (FSMWEFA) was used to identify the local rank map, (ii) WFA was applied to calculate the concentration profiles of H_nA and Aⁿ⁻ (selection of the window for application of WFA was performed using EFA), (iii) PVA was used to calculate H_{n − 1}A to HA spectral profiles, and (iv) a symmetry constraint, in addition to the non‐negativity constraint, was utilized to obtain the unique concentration and spectral profiles from different acceptable sets of profiles. In the absence of any selective region in the spectral data, the proposed soft method resulted in unique solution without rotational ambiguity. This study is the first application of symmetry constraint on concentration profiles. The rotational ambiguity drastically decreased on considering the constraint of symmetry of the H_{n − 1}A and HA concentration profiles, in addition to non‐negativity of profiles. Simulated examples were used to confirm these approaches. Effect of closeness of dissociation constants on the estimated values of constants was investigated. The results showed that when the difference between pK_a values is more than 1.2, the obtained errors in the estimation of pK_a values are less than about 6.5%. The considered real data were from pH‐metric titration of fluorescein. The obtained spectral and concentration profiles and the estimated pK_a values for fluorescein were in good agreement with the previously reported data. Copyright © 2009 John Wiley & Sons, Ltd.     

Normal and mixed partial second-order subdifferentials in variational analysis and optimization

A partial second-order subdifferential is defined here for extended real valued functions of two variables corresponding to its variables through coderivatives of first-order partial subdifferential mappings. In addition, some rules are presented to calculate these second-order structures along with defining some conditions to insure the equality \(\partial ^2_{yx}\) and \(\partial ^2_{xy}\). Moreover, as an application, some conditions are stated which show the relation between local minimum of a function and positiveness of principal minors of its hessian matrix.     

A hybrid extragradient method for solving pseudomonotone equilibrium problems using Bregman distance

In this paper, using a hybrid extragradient method, we introduce a new iterative process for approximating a common element of the set of solutions of equilibrium problems involving pseudomonotone bifunctions and the set of common fixed points of a finite family of multi-valued Bregman relatively nonexpansive mappings in the setting of reflexive Banach spaces. For this purpose, we introduce Bregman–Lipschitz-type condition for a pseudomonotone bifunction. It seems that these results for pseudomonotone bifunctions are first in reflexive Banach spaces. This paper concludes with certain applications, where we utilize our results to study the determination of a common point of the solution set of a variational inequality problem and the fixed point set of a finite family of multi-valued relatively nonexpansive mappings. A numerical example to support our main theorem will be exhibited.     

Cohen–Macaulay Modules in Dimension >s and Results on Local Cohomology

Let (R,𝔪) be a local ring and s ≥ ?1. Using the notion of M-sequence in dimension > s, we introduce Cohen–Macaulay modules in dimension > s. Among other things concerning Cohen–Macaulay modules in dimension > s, some finiteness results of the support and the associated primes of local cohomology modules are investigated.     

A competitive magnet-based genetic algorithm for solving the resource-constrained project scheduling problem

This paper presents a genetic algorithm for solving the resource-constrained project scheduling problem. The innovative component of the algorithm is the use of a magnet-based crossover operator that can preserve up to two contiguous parts from the receiver and one contiguous part from the donator genotype. For this purpose, a number of genes in the receiver genotype absorb one another to have the same order and contiguity they have in the donator genotype. The ability of maintaining up to three contiguous parts from two parents distinguishes this crossover operator from the powerful and famous two-point crossover operator, which can maintain only two contiguous parts, both from the same parent. Comparing the performance of the new procedure with that of other procedures indicates its effectiveness and competence.     

Voltammetric Determination of Bisphenol A in Water and Juice Using a Lanthanum (III)-Doped Cobalt (II,III) Nanocube Modified Carbon Screen-Printed Electrode

A La³⁺ doped Co₃O₄ nanocube modified graphite screen-printed electrode (La³⁺-doped Co₃O₄ nanocube/SPE) was prepared and utilized for the sensitive voltammetric determination of bisphenol A. In comparison with an unmodified electrode, the presence of the La³⁺ doped Co₃O₄ nanocubes caused a significant enhancement in the peak current. Differential pulse voltammetry (DPV), cyclic voltammetry (CV), and chronoamperometry approaches were utilized as diagnostic methods. The modified SPE was used to determine bisphenol A concentrations in the range from 0.5 to 900.0?μM with a limit of detection equal to 6.1?×?10^?8 M. Real samples were effectively analyzed with the modified electrode.     

Synthesis of Betti base derivatives catalyzed by nano-CuO-ionic liquid and experimental and quantum chemical studies on corrosion inhibition performance of them

Research on Chemical Intermediates - In this research, for the first time, aminonaphthol derivatives were introduced as efficient corrosion inhibitors. A linear polarization method was employed to...     

Response surface methodology for modelling and determination of catechin in Pistachio green hull using surfactant-based dispersive liquid–liquid microextraction followed by UV–Vis spectrophotometry

A rapid and simple approach for the preconcentration and determination of catechin from pistachio green hull samples has been proposed by surfactant-assisted dispersive liquid–liquid microextraction followed by UV–Vis spectrophotometry (SADLLME/UV–Vis). This method involved the formation of a catechin complex with cetylpyridinium chloride (CPC) as cationic surfactant, and subsequently, DLLME was applied to extract the catechin–CPC complex into chloroform. Different parameters affected the extraction efficiency were optimized by central composite design (CCD) and response surface methodology (RSM). In optimum condition, the calibration curve was linear in the range of 0.4–5 µg mL^??1 of catechin with correlation coefficient of 0.9982. The relative standard deviation based on five replicated analyses of 1 µg mL^??1 catechin was 1.85%. The proposed method was successfully applied for preconcentration and determination of trace amounts of catechin in pistachio hull samples.