Solid phase extraction�Cinductively coupled plasma spectrometry for adsorption of Co(II) and Ni(II) from radioactive wastewaters by natural and modified zeolites

Natural and modified clinoptilolite as low-cost adsorbents have been used for adsorption of Co(II) and Ni(II) from nuclear wastewaters both in batch and continuous experiments. Zeolite X was also synthesized and its ability towards the selected cations was examined. Kinetic and thermodynamic behaviors for the process were investigated and adsorption equilibrium was interpreted in term of Langmuir and Freundlich equations. The effect of various parameters including the initial concentration, temperature, ionic strength and pH of solution were examined to achieve the optimized conditions. The clinoptilolite was shown good sorption potential for Co(II) and Ni(II) ions at pH values 4?C6. Based on desorption studies, nearly 74 and 85% of adsorbed Co(II) and Ni(II) were removed from clinoptilolite by HCl. The Na⁺ and NH₄ ⁺ forms of clinoptilolite were the best modified forms for the removal of investigated cations. It is concluded that the selectivity of clinoptilolite is higher for Co(II) than Ni(II). The synthesized zeolite showed more ability to remove cobalt and nickel ions from aqueous solution than the natural clinoptilolite. The microwave irradiation was found to be more rapid and effective for ion exchange compared to conventional ion exchange process.     

Suppression of Pulmonary Tumor Promotion and Induction of Apoptosis by <Emphasis Type="Italic">Crocus sativus</Emphasis> L. Extraction

Crocus sativus L., commonly known as saffron, is the raw material for one of the most expensive spice in the world, and it has been used in folk medicine for centuries. We investigated the potential of the ethanolic extract of saffron to induce cytotoxic and apoptosis effects in carcinomic human alveolar basal epithelial cells (A549), a commonly used cell culture system for in vitro studies on lung cancer. The cells were cultured in Dulbecco’s modified Eagle’s medium with 10% fetal bovine serum treated with different concentrations of the ethanolic extract of saffron for two consecutive days. Cell viability was quantitated by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. Apoptotic cells were determined using annexin V–fluorescein isothiocyanate by flow cytometry. Saffron could decrease the cell viability in the malignant cells as a concentration- and time-dependent manner. The IC₅₀ values against the A549 cell lines were determined as 1,200 and 650 μg/ml after 24 and 48 h, respectively. Saffron-induced apoptosis of the A549 cells in a concentration-dependent manner, as determined by flow cytometry histogram of treated cells that induced apoptotic cell death, is involved in the toxicity of saffron. It might be concluded that saffron could cause cell death in the A549 cells, in which apoptosis plays an important role. Saffron could also be considered as a promising chemotherapeutic agent in lung cancer treatment in future.     

UV-protection and photocatalytic properties of electrospun polyacrylonitrile nanofibrous mats coated with TiO<Subscript>2</Subscript> nanofilm via sol–gel

UV radiation causes serious damage to skin, and a protective system capable of absorbing or reflecting UV radiation is required to protect skin. This paper describes the UV protection and photocatalytic properties of TiO₂ nanofilm coated electrospun polyacrylonitrile (PAN) nanofibrous mats with various nanofiber diameter and area density. The mats were coated by sol–gel process. The results of this research showed that sol–gel is capable of coating porous nanofibrous mats with a weight increase as low as 0.8%. The TiO₂ nanofilm coated on the nanofibrous mats has a considerable effect on its UV protection. The UV protection factor (UPF) of the mats increases with decreasing nanofiber diameter. In fact decreasing the diameter of nanofibers of the TiO₂ nanofilm coated PAN nanofibrous mats increases their photocatalytic activity. Moreover, this research showed that TiO₂ nanofilm produced through sol–gel process on the PAN nanofibers has a crystalline structure. The UPF of the nanofibrous mat coated with a TiO₂ nanofilm via sol–gel process can be classified as excellent.     

Bioassay studies of cobalt (II) complexes of modified diamine

Coordination compounds of modified diamine, the basic unit of which are ethylenediamine, with that of Co (II) are prepared. The modified diamines are ethylenediaceticacid (EDDA) and N,N,N,N-tetaraethylene-1,2-diamine (TEEDA). These diamines are characterized through ¹H-NMR, ¹³C-NMR, elemental analysis and IR techniques. Cobalt (II) complexes of these two ligands were prepared and characterized by physical measurements including elemental analysis, IR, UV-Visible, magnetic susceptibilities and conductance measurements. Antibacterial activities are also carried out in order to investigate the biological activity upon complexation. They were screened against four pathogenic bacteria like Escherichia coli, Pseudomonas aeroginosa, Klesbella pneumonia and Staphylococcus aureus. The results showed significant enhancement in activities.     

Optimization of the simultaneous determination of imatinib and its major metabolite, CGP74588, in human plasma by a rapid HPLC method using D-optimal experimental design

A simple, rapid and specific HPLC method has been developed and validated for the simultaneous determination of imatinib, a tyrosine kinase inhibitor, and its major metabolite, CGP74588, in human plasma. The optimization of the HPLC procedure involved several variables, of which the influences of each was studied. After a series of preliminary-screening experiments, the composition of the mobile phase and the pH of the added buffer solution were set as the investigated variables, while the resolution between imatinib and CGP74588 peaks, the retention time and the imatinib peak width were chosen as the dependent variables. Applying D-optimal design, the optimal chromatographic conditions for the separation were defined. The method proved to show good agreement between the experimental data and predictive values throughout the studied parameter range.The optimum assay conditions were achieved with a Chromolith™ Performance RP-8e 100 mm × 4.6 mm column and a mixture of methanol/acetonitrile/triethylamine/diammonium hydrogen phosphate (pH 6.25, 0.048 mol L⁻¹) (20:20:0.1:59.9, v/v/v/v) as the mobile phase at a flow rate of 2 mL min⁻¹ and detection wavelength of 261 nm. The run time was less than 5 min, which is much shorter than the previously optimized methods. The optimized method was validated according to FDA guidelines to confirm specificity, linearity, accuracy and precision.     

An experimental and theoretical investigation of the regio- and stereoselectivity of the polar [3+2] cycloaddition of azomethine ylides to nitrostyrenes

The regio- and stereochemical polar [3+2] cycloaddition of the azomethine ylides, which were generated in situ by the reaction of isatin derivatives and proline, with trans-β-nitrostyrene and (E)-1-phenyl-2-nitropropene were studied using experimental and theoretical methods. In comparison with trans-β-nitrostyrene, when the reactions were performed with (E)-1-phenyl-2-nitropropene, a remarkable inversion in the regioselectively was observed. The regioselectivity of the reactions was investigated using global and local reactivity indices and frontier molecular orbital (FMO) analysis at the B3LYP/6-31G(d,p) level of theory. The effects of the electronic and steric factors on the regioselectivity of the reactions were discussed. The inspection of geometries and energetics of transition states revealed the importance of weak interactions in regioselectivity of the cycloaddition reactions.     

Investigation of the effect of using various HFC refrigerants in geothermal heat pump with residential heating applications

Journal of Thermal Analysis and Calorimetry - In the present investigation, the impact of various refrigerants on the efficiency of the geothermal heat pump operation is investigated. Appropriate...     

Computational study of a latent heat thermal energy storage system enhanced by highly conductive metal foams and heat pipes

Numerical simulations are performed to analyze the thermal characteristics of a latent heat thermal energy storage system with phase change material embedded in highly conductive porous media. A network of finned heat pipes is also employed to enhance the heat transfer within the system. ANSYS-FLUENT 19.0 is used to create a transient multiphase computational model to simulate the thermal behavior of the storage unit. Copper foam is the porous medium used to enhance the heat transfer and is impregnated with the phase change material, potassium nitrate (KNO₃). The effects of the porosity of the metal foam and the quantity of heat pipes on the thermal characteristics of storage unit have been investigated. The results indicated that increasing the quantity of the embedded heat pipes leads to drastic acceleration of both charging and discharging process. Impregnating the copper foam with potassium nitrate phase change material significantly affects the total charging and discharging times of the storage unit. It was shown that the porosity of the metal foam plays a key role in the thermal behavior of the system during the charging and discharging processes.

     

Synthesis of 1-amidoalkyl-2-naphthol derivatives using a magnetic nano-Fe3O4@SiO2@Hexamethylenetetramine-supported ionic liquid as a catalyst under solvent-free conditions

Hexamethylenetetramine-functionalized silica-coated nano-Fe₃O₄ particles (MNPs@Hexamethylenetetramine) were prepared as a reusable heterogeneous catalyst using a facile process. The catalyst was synthesized and characterized using infrared, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and vibrating sample magnetometer. This magnetic nanocatalyst was employed as an efficient, reusable, and environmentally benign heterogeneous catalyst for the synthesis of amidoalkylnaphthol derivatives from a one-pot three-component condensation reaction of beta-naphthol, aldehydes, and amides in good to excellent yields, Moreover, this catalyst can be easily recovered by using a magnetic field and directly reused for at least seven runs without sign ificant loss of its activity.     

Novel N-(benzo[d]oxazol-2-yl)alkanamides; synthesis and carbonic anhydrase II inhibition studies

Carbonic anhydrase (CA II) inhibitors are very important therapeutic targets in drug design for treatment of neuropathic pain and in eradication of glaucoma, cancer, epilepsy, ulcer and obesity. In this study, some two2-substituted benzoxazoles ( 3a-j ) were developed as a new family of carbonic anhydrase II inhibitors by employing acyl thiourea chemistry via a simple and expedient protocol and evaluated for CA II inhibitor activity and radical scavenging ability. Compounds 3f and 3j were found to be the most potent inhibitors, with IC₅₀ values of 0.00564 and 0.00596 μM, respectively which are several times better than that of the standard, acetazolamide (IC₅₀ value 0.997 ± 0.0586 μM). Docking experiments were carried out against the carbonic anhydrase II crystal structure to better rationalize the inhibitory activities of these new structures. Moreover, the results of a DPPH radical scavenging assay showed that the antioxidant profile of compound 3i is superior to those of other derivatives. The results have revealed that derivatives 3f and 3j behave as CA-II inhibitors significantly better than standard and 3i has good anti-oxidation potential.