Development a Novel Integrated Distributed Multi-objective Simulation-optimization Model for Coastal Aquifers Management Using NSGA-II and GMS Models

Water Resources Management - Groundwater is one of the most valuable water resources in the world in terms of quantity and quality. Therefore, their protection as an important issue should be...     

An Electrochemical Nanosensor for Simultaneous Voltammetric Determination of Ascorbic Acid and Sudan I in Food Samples

In this work, we describe application of a high-sensitive electrochemical sensor for determination of ascorbic acid (AA) in the presence of high concentration of Sudan I in food samples. In the first step, we study synthesis and characterization of NiO/NPs with X-ray diffraction (XRD) method. In the second step, application of NiO/NPs describe in the preparation of carbon-paste electrode modified with (9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)-4-ethylbenzene-1,2-diol (DEDED) as a high-sensitive and selective voltammetric sensor for determination of AA and Sudan I. The electrocatalytic oxidation of AA at the modified electrode was investigated by cyclic voltammetry, chronoamperometry and square wave voltammetry (SWV). For the mixture containing AA and Sudan I, the peaks potential was well separated from each other. Their square wave voltammetrics peaks current increased linearly with their concentration at the ranges of 0.01–600 and 0.5–1,000 μM, with the detection limits of 0.006 and 0.2 μM, respectively. Finally, the proposed method was also examined as a selective, simple, and precise electrochemical sensor for the determination of AA and Sudan I in real samples such as fruit juices, fresh vegetable juice, chilli sauce and tomato sauce.     

Methotrexate-grafted-oligochitosan micelles as drug carriers: synthesis and biological evaluations

The novel amphiphilic derivatives of Methotrexate–chitosan oligosaccharide (MTX–CHO) with different molar feeding ratios of MTX were synthesized. The degree of MTX substitution ranged from 4.47 to 13.5 %. MTX–CHO copolymer formed micelles with an average size of 134.6 ± 14.52 to 236.6 ± 30.01 nm, and zeta potential of 20 ± 5 to 16.8 ± 7.74 mV. The critical micelle concentration was found to range from 125 to 0.56 mg/l. Analysis of micelles with different degree of substitutions (DSs) revealed that the size of micelles decreased by increasing DS while zeta potential was reduced. Release study indicated that drug content had effect on the release rate. With increasing amount of loaded drug in the micelle, release rate was decreased. Drug loaded and unloaded MTX–CHO micelles showed significant cytotoxicity on MDA-MB-231. Loaded micelle was more effective than unloaded one which indicated that conjugation could reduce efficacy of MTX. The viability of MDA-MB-231 in presence of drug loaded micelles was significantly decreased and cell viability at 1 µg/ml was 45.17 ± 9 % while the viability of unloaded micelles was 91.86 ± 9.88. These phenomena make MTX–CHO micelles as a good candidate for hydrophobic anticancer drug carrier.     

2,3-Diphenylquinoxaline-4′,4″-dioxytriethylene glycol as a sensing and selective material for construction of strontium-PVC membrane sensor

The PVC membrane containing 2,3-diphenylquinoxaline-4′,4″-dioxytriethylene glycol (PQTEG) as a suitable ionophore, presents a linear dynamic range of 1.0 × 10^? 6–1.0 × 10^? 2 M with a Nernstian slope of 29.9 mV per decade and a detection limit of 6.7 × 10^? 7 M. The response time is quick (smaller than 15 s), it can be used in the pH range of 4.1–8.9 and its duration is at least 55 days without noticing any considerable potential divergence. The proposed electrode has very good selectivity with respect to all common alkali, alkaline earth in the range of ? 3.28 to ? 4.00, and for transition metal ions in the range of ? 3.38 to ? 4.00. It was successfully applied as an indicator electrode in potentiometric titration of Sr(II) ions with EDTA.     

Adsorption of Thorium from Aqueous Solution using Nanoporous Adsorbents: Effect of Contact Time,pH, Initial Concentration,and Temperature

Nanoporous silicates MCM-41 have been prepared using different surfactants such as cetyltrimethylammonium bromide (C₁₆TAB) and dodecyltrimethylammonium bromide (C₁₂TAB) as template. The adsorbents are characterized using powder x-ray diffraction, nitrogen adsorption-desorption isotherm data, scanning electron microscopy, and transmission electron microscopy. The thorium sorption was studied as a function of shaking time, pH, initial concentration, and temperature. The sorption of thorium at the determined optimum conditions follows Langmuir and Freundlich isotherms. The results show that the nanoporous MCM-41 synthesized by C₁₂TAB has more adsorption capacity than the MCM-41 synthesized by C₁₆TAB (77.6 µmol · g^?1 vs. 52.1 µmol · g^?1) at 25°C. Th(IV) adsorption onto nanoporous adsorbents was very fast process and therefore, this adsorbent is suitable for column separation. Thermodynamic parameters such as ΔH°, ΔS° and ΔG° were found to be 47.76 KJ · mol^?1, 196.21 J · mol^?1 · K^?1, and 19.00 KJ · mol^?1, respectively (at 298 K). The positive value ΔH° suggested the endothermic nature of adsorption and negative ΔG° indicates the feasibility and spontaneity of the adsorption process.