ZnO nanoparticle-modified ionic liquid-carbon paste electrodefor voltammetric determination of folic acid in food and pharmaceutical samples

In this work, a ZnO/nanoparticles (NPs) modified carbon ionic liquid paste electrode (ZnO/NP/CILPE) was fabricated and used to investigate the electrochemical behavior of folic acid. ZnO/NP/CILPE was prepared by mixing hydrophilic ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([C₄mim]-[PF₆])), ZnO/NPs, graphite powder, and liquid paraffin together. The fabricated ZnO/NP/CILPE showed great electrocatalytic ability to the oxidation of folic acid, and an irreversible oxidation peak appeared at 0.75 V (vs. Ag/AgCl) with improved peak current. Under the optimized conditions of pH 9.0, the plot of peak current vs. folic acid concentration consisted of two linear segments with slopes of 1.776and 0.033 μA/μM in the concentration ranges of 0.05–1.5 μM and 1.5–550.0 μM, respectively. The detection limit was 0.01 μM (3σ). The proposed sensor was successfully applied for the determination of folic acid in fortified food and pharmaceutical samples.     

Synthesis and Evaluation of a Molecularly Imprinted Polymer for Pre-concentration of Patulin from Apple Juice

Patulin, (4-hydroxy-4H-furo[3,2-c] pyran-2(6H)-one) is a toxic secondary metabolite produced by a wide range of fungal species growing on some fruits, including apples. A novel molecularly imprinted polymer (MIP) for patulin has been synthesized using oxindole as a dummy template. The synthesis of MIPs based on dummy templates is a solution to overcome “template bleeding” shortcoming in trace analysis. The polymer was prepared in a non-covalent approach with methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linker via free radical polymerization. It was revealed that the MIP particles in extraction columns displayed high affinity towards patulin and, therefore, subsequently employed for molecularly imprinted-solid phase extraction (MIP-SPE) of patulin from contaminated apple juice samples. The analysis of spiked samples showed good recoveries (>80%). Reproducibility, repeatability, and limit of detection of the proposed method were also investigated.     

A branch and bound algorithm for hybrid flow shop scheduling problem with setup time and assembly operations

A hybrid flow shop scheduling problem (HFSP) with assembly operations is studied in this paper. In the considered problem, a number of products of the same kind are produced. Each product is assembled using a set of several parts. At first, the parts are produced in a hybrid flow shop and then they are assembled in an assembly stage to produce products. The considered objective is to minimize the completion time of all products (makespan). This problem has been proved strongly NP-hard, so in order to solve it, a hierarchical branch and bound algorithm is presented. Also, some lower and upper bounds are developed to increase the efficiency of the proposed algorithm. The numerical experiments are used to evaluate the performance of the proposed algorithm.     

On the Circular Chromatic Number of Graph Powers

This article intends to study some functors from the category of graphs to itself such that, for any graph G, the circular chromatic number of is determined by that of G. In this regard, we investigate some coloring properties of graph powers. We show that provided that . As a consequence, we show that if , then . In particular, and has no subgraph with circular chromatic number equal to . This provides a negative answer to a question asked in (X. Zhu, Discrete Math, 229(1–3) (2001), 371–410). Moreover, we investigate the nth multichromatic number of subdivision graphs. Also, we present an upper bound for the fractional chromatic number of subdivision graphs. Precisely, we show that .     

Broad sub-continuum resonances and the case for finite-energy sum-rules

There is a need to go beyond the narrow resonance approximation for QCD sum-rule channels which are likely to exhibit sensitivity to broad resonance structures. We discuss how the first two Laplace sum rules are altered when one goes beyond the narrow resonance approximation to include possible subcontinuum resonances with nonzero widths. We show that the corresponding first two finite energy sum rules are insensitive to the widths of such resonances, provided their peaks are symmetric and entirely below the continuum threshold. We also discuss the reduced sensitivity of the first two finite energy sum rules to higher dimensional condensates, and show these sum rules to be insensitive to dimension condensates containing at least one pair. We extract the direct single-instanton contribution to the sum rule for the longitudinal component of the axial-vector correlation function from the known single-instanton contribution to the lowest Laplace sum rule for the pseudoscalar channel. Finally, we demonstrate how inclusion of this instanton contribution to the finite-energy sum rule leads to both a lighter quark mass and to more phenomenologically reasonable higher-mass-resonance contributions within the pseudoscalar channel. Received: 15 September 1997 / Revised version: 15 November 1997 / Published online: 26 February 1998     

A memetic algorithm for minimizing the total weighted completion time on a single machine under linear deterioration

In this paper, we consider the problem of minimizing the total weighted completion time on a single machine. Jobs processing times are increasing linear function of start times. First, we present some new dominance properties for this NP-hard problem. And next, using these properties, we develop a memetic algorithm for the problem. The results of computational experiments show the good performance of the proposed algorithm.     

Ultrasound‐assisted dispersive micro‐solid‐phase extraction based on N‐doped mesoporous carbon and high‐performance liquid chromatographic determination of 1‐hydroxypyrene in urine samples

In this research, a new ultrasound‐assisted dispersive micro‐solid‐phase extraction method based on N‐doped mesoporous carbon sorbent followed by high‐performance liquid chromatography equipped with diode array detector for trace measurement of 1‐hydroxypyrene as a metabolite of exposure to polycyclic aromatic hydrocarbons was optimized. Herein, the hard template method was used for the preparation of N‐doped mesoporous carbon sorbent. The prepared sorbent was characterized using the Brunauer–Emmett–Teller method, transmission electron microscopy, and elemental analysis. Parameters affecting the extraction of the target metabolite were investigated using the Box–Behnken design method. Considering optimum parameters, the plotted calibration curve for 1‐hydroxypyrene was linearly correlated with the concentration span of 0.1–50 μg/L for urine media. The accuracy of the optimized procedure was examined through the relative recovery tests on the fortified urine specimens. The relative recoveries fell between 95 and 101%. The method detection limit of the proposed procedure was also calculated to be 0.03 μg/L.     

Polarization-Dependent Mode Analyzer and Controlled-Z Gate in Ti:LiNbO3 Quantum Photonic Circuits

Abstract

On-chip integrated photonic circuits are crucial for further progress toward quantum technologies and in the science of quantum optics. The quantum controlled-Z gate is an example of the maximally entangling gate, which is universal for quantum computing when coupled with single-qubit gates. This article demonstrates a deterministic controlled-Z photonic quantum gate based on titanium in-diffused channel waveguides in which polarization and modal degrees of freedom of a single photon are used for encoding the control and target qubits, respectively.     

Stress analysis of orthotropic planes weakened by cracks

The stress fields in an orthotropic infinite plane containing Volterra type climb and glide edge dislocations are derived. The dislocation solutions are utilized to formulate integral equations for dislocation density functions on the surfaces of smooth cracks. The integral equations are of Cauchy singular type and are solved for several different cases of crack configurations and arrangements. The results are used to evaluate modes I and II stress intensity factors for multiple smooth cracks.