A new Approach for the Voltammetric Sensing of the Phytoestrogen Genistein at a Non-modified Boron-doped Diamond Electrode

An effective electrochemical sensor was constructed using an unmodified boron-doped diamond electrode for determination of genistein by square-wave voltammetry. Cyclic voltammetric investigations of genistein with HClO₄ solution indicated that irreversible behavior, adsorption-controlled and well-defined two oxidation peaks at about +0.92 (P_A1) & +1.27 V (P_A2). pH, as well as supporting electrolytes, are important in genistein oxidations. Quantification analyses of genistein were conducted using its two oxidation peaks. Using optimized experiments as well as instrumental conditions, the current response with genistein was proportionately linear in the concentrations range of 0.1 to 50.0 μg mL⁻¹ (3.7×10⁻⁷−1.9×10⁻⁴ mol L⁻¹), by the detection limit of 0.023 μg mL⁻¹ (8.5×10⁻⁸ mol L⁻¹) for P_A1 and 0.028 μg mL⁻¹ (1.1×10⁻⁷ mol L⁻¹) for P_A2 in 0.1 mol L⁻¹ HClO₄ solution (in the open circuit condition at 30 s accumulation time). Ultimately, the developed method was effectively applied to detect genistein in model human urine samples by using its second oxidation peak (P_A2).     

Convergence properties and practical estimation of the probability of rank reversal in pairwise comparisons for multi-criteria decision making problems

In this paper, we address the impact of uncertainty introduced when the experts complete pairwise comparison matrices, in the context of multi-criteria decision making. We first discuss how uncertainty can be quantified and modeled and then show how the probability of rank reversal scales with the number of experts. We consider the impact of various aspects which may affect the estimation of probability of rank reversal in the context of pairwise comparisons, such as the uncertainty level, alternative preference scales and different weight estimation methods. We also consider the case where the comparisons are carried out in a fuzzy manner. It is shown that in most circumstances, augmenting the size of the expert group beyond 15 produces a small change in the probability of rank reversal. We next address the issue of how this probability can be estimated in practice, from information gathered simply from the comparison matrices of a single expert group. We propose and validate a scheme which yields an estimate for the probability of rank reversal and test the applicability of this scheme under various conditions. The framework discussed in the paper can allow decision makers to correctly choose the number of experts participating in a pairwise comparison and obtain an estimate of the credibility of the outcome.     

Crystal structure and computational studies of (E)-1-(benzo[b]thiophen-3-yl)-N-(4-ethoxyphenyl)methanimine

Crystallography Reports - The title compound, C17H15NOS, crystallizes in the orthorhombic sp. gr. Pca21. Two molecules in the asymmetric unit have similar structure. Crystal structure contains weak...     

ELECTRORHEOLOGICAL PROPERTIES OF POLYANILINE/PUMICE COMPOSITE SUSPENSIONS

Electrorheological （ER） properties of polyaniline （PAni）, pumice and polyaniline/pumice composites （PAPC） were investigated. Polyaniline and PAni/pumice composite were prepared by oxidative polymerization. PAni/pumice particlesbased ER suspensions were prepared in silicone oil （SO）, and their ER behavior was investigated as a function of shear rate, electric field strength, concentration and temperature. Sedimentation stabilities of suspensions were determined. It has been found that ER activity of all the suspensions increases with increasing electric field strength, concentration and decreasing shear rate. It has shown that the suspensions have a typical shear thinning non-Newtonian viscoelastic behavior. Yield stress of composite suspensions increased linearly with increasing applied electric field strength and with concentrations of the particles. The effect of high temperature on ER activity of purrfice/silicone oil systems was also investigated.     

Mathematical models for job-shop scheduling problems with routing and process plan flexibility

As a result of rapid developments in production technologies in recent years, flexible job-shop scheduling problems have become increasingly significant. This paper deals with two NP-hard optimization problems: flexible job-shop scheduling problems (FJSPs) that encompass routing and sequencing sub-problems, and the FJSPs with process plan flexibility (FJSP-PPFs) that additionally include the process plan selection sub-problem. The study is carried out in two steps. In the first step, a mixed-integer linear programming model (MILP-1) is developed for FJSPs and compared to an alternative model in the literature (Model F) in terms of computational efficiency. In the second step, one other mixed-integer linear programming model, a modification of MILP-1, for the FJSP-PPFs is presented along with its computational results on hypothetically generated test problems.     

Cloud point extraction procedure for flame atomic absorption spectrometric determination of lead(II) in sediment and water samples

The conditions for cloud point extraction of lead(II) from aqueous solutions were investigated and optimized. The procedure is based on the separation of Pb(II) – brillant cresyl blue (BCB) complexes into the micellar media by adding the surfactant Triton X-114. After phase separation, the surfactant-rich phase was dissolved with 1 mol L⁻¹ HNO₃ in ethanol and diluted with 1 mol L⁻¹ HNO₃ solution before lead was determined by flame atomic absorption spectrometry. Optimization of the pH, ligand and surfactant quantities, incubation time, temperature, viscosity, sample volume, and interfering ions was performed. The effects of the matrix ions were also examined. The detection limits for three times the standard deviations of the blank for lead were 7.5 μg L⁻¹ for water samples and 0.33 μg g⁻¹ for sediment samples. The validity of cloud point extraction was checked by employing certified reference samples of Lake Sediment IAEA-SL-1 and Sewage Sludge BCR-CRM 144R. The procedure was applied to natural waters and sediment samples with satisfactory results (recoveries >95%, relative standard deviations <6.4%).     

Refractive index enhancement in a far-off resonant atomic system

We demonstrate a scheme where a laser beam which is very far detuned from an atomic resonance experiences a large index of refraction with vanishing absorption. The essential idea is to excite two Raman resonances with appropriately chosen strong control lasers.     

Optical frequency conversion by a rotating molecular wave plate

We demonstrate efficient four-wave mixing in low-pressure molecular deuterium without the need for phase matching. We use two laser fields with opposite circular polarizations to produce a strong excitation of a rovibrational transition at a frequency of 3167 cm(-1) . The coherent molecular motion, in turn, modulates a third laser field (also circularly polarized) and results in highly efficient single-sideband conversion.