Synthesis of calcium peroxide nanoparticles as an innovative reagent for in situ chemical oxidation

Chemical oxidation is one of the many different methods of site remediation that has emerged lately as an alternative method to traditional techniques. According to this research calcium peroxide is suitable choice for contaminant biodegradation in soil and ground water but speed of oxidation reaction between calcium peroxide and contaminant is slow. Synthesis of calcium peroxide in nano size by increased ratio of surface to volume can increase the speed of reaction and solve the problem. We have developed a simple surface modification technique to avoid irreversible agglomeration of calcium peroxide nanoparticles. The technique is based on hydrolysis-precipitation procedure, using CaCl₂ as a precursor. Polyethylene glycol 200 (PEG200) is used as a surface modifier. CaO₂ was identified and studied by characterization techniques, including XRD and TEM. The results indicate the ability of this method for synthesis of new reagent in nano size and improve quality of in situ chemical oxidation. Size determination by TEM image indicates the size of calcium peroxide nanoparticles approximately 15-25 nm.     

Regional water quality management for the Karun–Dez River basin, Iran

To achieve water quality goals in a river basin, a water quality management model (WQMM) has been developed through the geographic information system (GIS) approach and a mathematical water quality model. The developed model has been applied to the Karun and Dez Rivers, where water quality has decreased due to heavy pollutant loads from Khuzestan province cities and surrounding areas. Pollution sources, land use, geographic features and measured water quality data of the river basin were incorporated into the Arc‐View GIS database. With the database, the management model calculated management type and management cost for each management project in the river basin. Until now, river management policy for polluted rivers in Iran first penalizes pollution sources and then constructs treatment plants for the pollution sources whose wastewater is released untreated and for which the wastewater quality goal of the Iranian Department of Environment is not met. Different management projects with a time programme were proposed and they were compared with the results of the river quality without any management approach. It became clear that the results based on the management approach were much better than those for the unmanaged condition from the viewpoint of the achievement of water quality goals and cost optimization.     

Investigation of the electrochemical behavior of some catecholamines in the presence of 4-aminobenzoic acid

Electrochemical oxidation of some catecholamines such as dopamine (1), l-dopa (2) and methyldopa (3) has been studied in the presence of 4-aminobenzoic acid (4). Some electrochemical techniques such as cyclic voltammetry using diagnostic criteria derived by Nicholson and Shain for various electrode mechanisms and controlled-potential coulometry were used. Variation in cathodic peaks due to the competition between intramolecular and intermolecular Michael addition reaction was studied in various pH values, and the best conditions for reaction with 4-aminobenzoic acid was obtained. The results indicate an ECE mechanism. The observed homogeneous rate constant (k_obs) for Michael addition reaction was estimated by comparing the experimental cyclic voltammetric responses with the digital simulated results. Also, the Michael addition reaction rate constants (k_m) were calculated using microscopic acidic dissociation constant of ammonium groups in 4-aminobenzoic acid. The chemical oxidation reaction of catecholamines with periodate in the presence of 4-aminobenzoic acid was also studied spectrophotometrically.     

On the motion of superparamagnetic particles in magnetic drug targeting

A stochastic ODE model is developed for the motion of a superparamagnetic cluster suspended in a Hagen-Poiseuille flow and guided by an external magnet to travel to a target. The specific application is magnetic drug targeting, with clusters in the range of 10–200 nm radii. As a first approximation, we use a magnetic dipole model for the external magnet and focus on a venule of 10⁻⁴ m radius close to the surface of the skin as the pathway for the clusters. The time of arrival at the target is calculated numerically. Variations in release position, background flow, magnetic field strength, number of clusters, and stochastic effects are assessed. The capture rate is found to depend weakly on variations in the velocity profile, and strongly on the cluster size, the magnetic moment, and the distance between the magnet and the blood vessel wall. A useful condition is derived for the optimal capture rate. The case of simultaneous release of many clusters is investigated. Their accumulation in a neighborhood of the target at the venule wall follows a normal distribution with the standard deviation roughly half of the distance between the magnet and the target. Ideally, this deviation should equal the tumor radius, and the magnet should be beneath the center of the tumor. The optimal injection site for a cluster is found to be just prior to arrival at the target. Two separate mechanisms for capturing a cluster are the magnetic force and, for radii smaller than 20 nm, Brownian motion. For the latter case, the capture rate is enhanced by Brownian motion when the cluster is released near the wall.     

Solvent-Induced Formation of Novel Ni(II) Complexes Derived from Bis-Thiosemicarbazone Ligand: An Insight from Experimental and Theoretical Investigations

In this work, we report solvent-induced complexation properties of a new N₂S₂ tetradentate bis-thiosemicarbazone ligand (H₂L^I), prepared by the condensation of 4-phenylthiosemicarbazide with bis-aldehyde, namely 2,2’-(ethane-1,2-diylbis(oxy)dibenzaldehyde, towards nickel(II). Using ethanol as a reaction medium allowed the isolation of a discrete mononuclear homoleptic complex [NiL^I] (1), for which its crystal structure contains three independent molecules, namely 1-I, 1-II, and 1-III, in the asymmetric unit. The doubly deprotonated ligand L^I in the structure of 1 is coordinated in a cis-manner through the azomethine nitrogen atoms and the thiocarbonyl sulfur atoms. The coordination geometry around metal centers in all the three crystallographically independent molecules of 1 is best described as the seesaw structure. Interestingly, using methanol as a reaction medium in the same synthesis allowed for the isolation of a discrete mononuclear homoleptic complex [Ni(L^II)₂] (2), where L^II is a monodeprotonated ligand 2-(2-(2-(2-(dimethoxymethyl)phenoxy)ethoxy)benzylidene)-N-phenylhydrazine-1-carbothioamide (HL^II). The ligand L^II was formed in situ from the reaction of L^I with methanol upon coordination to the metal center under synthetic conditions. In the structure of 2, two ligands L^II are coordinated in a trans-manner through the azomethine nitrogen atom and the thiocarbonyl sulfur atom, also yielding a seesaw coordination geometry around the metal center. The charge and energy decomposition scheme ETS-NOCV allows for the conclusion that both structures are stabilized by a bunch of London dispersion-driven intermolecular interactions, including predominantly N–H∙∙∙S and N–H∙∙∙O hydrogen bonds in 1 and 2, respectively; they are further augmented by less typical C–H∙∙∙X (where X = S, N, O, π), CH∙∙∙HC, π∙∙∙π stacking and the most striking, attractive long-range intermolecular C–H∙∙∙Ni preagostic interactions. The latter are found to be determined by both stabilizing Coulomb forces and an exchange-correlation contribution as revealed by the IQA energy decomposition scheme. Interestingly, the analogous long-range C–H∙∙∙S interactions are characterized by a repulsive Coulomb contribution and the prevailing attractive exchange-correlation constituent. The electron density of the delocalized bonds (EDDB) method shows that the nickel(II) atom shares only ~0.8|e| due to the σ-conjugation with the adjacent in-plane atoms, demonstrating a very weak σ-metalloaromatic character.     

Functional orange juice enriched with encapsulated polyphenolic extract of lime waste and hesperidin

Polyphenolic extract from lime waste and hesperidin were encapsulated to reduce the bitter taste of flavonoid glycosides, mitigate destruction of nutrients during heat process and increase the nutrition value of orange juice. The properties of polyphenolic extract of lime waste, encapsules, the physicochemical and the sensory factors of enriched orange juice during storage were measured. The value of yield of the process (Y) and encapsulation efficiency (EE) was obtained within the range of 85–90% and 59–71%, respectively. The particle size of samples was reported within the range of 27–41 μm. The physicochemical properties in treatments follow the same pattern when compared with the control sample in 60‐day storage. In the sensory assessment, encapsulated formulas were considered to have the best treatment. If the hesperidin was not encapsulated, 80% of it would have been destroyed during pasteurisation, while when encapsulated, only 18.8–33.18% of hesperidin was destroyed.     

Novel Sensor Fabrication for the Determination of Nanomolar Concentrations of Hg2+ in Some Foods and Water Samples Based on Multi-walled Carbon Nanotubes/Ionic Liquid and a New Schiff Base

The air and water stable room temperature ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [BMP]Tf₂N, multi-walled carbon nanotubes (MWCNTs), graphite powder and also a new synthesized Schiff base have been used to fabricate a new carbon composite electrode with very attractive sensing behavior. The new Schiff base was synthesized to apply as a selective agent in electrochemical responses of the voltammetric sensor for the determination of mercury (II) ions in aqueous solutions. The proposed sensor allowed the determination of mercury (II) in the wide linear dynamic range of 0.2–260.0 nmol l^?1. The limit of detection (LOD) was noticed to be 0.05 nmol l^?1. The prepared electrode was used for mercury (II) determination in the real samples.