Enhancing of asphaltene adsorption onto Fe3O4 nanoparticles coated with metal-organic framework Mil-101 (Cr) for the inhibition of asphaltene precipitation

In this study, the potential of MOF (Mil-101-Cr)-coated Fe₃O₄ magnetic nanoparticles (Fe₃O₄-MOF MNPs) for asphaltene adsorption was investigated for the first time and the results were compared with magnetic Fe₃O₄ nanoparticles (Fe₃O₄ MNPs). The coprecipitation method was used for the synthesis of both nanoparticles and were verified using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FE-SEM). The initial asphaltene concentration, nanoparticles concentration, and temperature were the investigated parameters that influenced the adsorption capacity. Increasing the asphaltene concentration, decreasing the mass of nanoparticles, and reducing the temperature could enhance the maximum asphaltene adsorption capacities of 0.79 for Fe₃O₄ MNPs and 0.98?mg?m^?2 for Fe₃O₄-MOF MNPs. Adsorption isotherms tests showed that the Langmuir model was in agreement with the experimental data. In addition, the evaluation of adsorption kinetics demonstrated that the pseudo-second-order Lagergren model predicted the results more precisely. The amount of asphaltene adsorption for Fe₃O₄-MOF MNPs was higher than that for Fe₃O₄ MNPs. These results recommend the application of MOF as an appropriate and effective coating for enhancing asphaltene adsorption.     

Multi elemental neutron activation analysis of popular medicinal plants used to prevent blood lipid disorders

In this study, five of popularly used medicinal plants as Cichorium intybus, Anethum graveolens seed, Thymus vulgaris, Fumaria officinalis and Hibiscus sabdariffa Syn: Hibiscus gossypifolius were prepared from Herbal Pharmacies in Tehran. The amounts of Al, Br, Ca, Cl, Cr, Fe, K, Mg, Mn, Na, V and Zn in samples were determined using instrumental neutron activation analysis. In this method, Tehran research reactor as a neutron source and relative INAA have been used as the analysis procedure. Highest levels of Cr (5 mg/kg), Ca (28316 mg/kg) and Mg (4134 mg/kg) were detected in Thymus vulgaris and F1umaria officinalis, respectively.     

Scattering of a spherical wave from the coupling of two half-planes

Summary  The diffraction of a spherical acoustic wave from the juncture of pressure release (soft) and locally reacting (absorbing) half-planes in a fluid moving at subsonic velocity is examined. This consideration is important because the point sources are regarded as better substitutes for real sources than line sources/plane waves. The integral representation of the field is obtained using integral transforms and the Wiener-Hopf technique. The factorization of the kernel function in the Wiener-Hopf functional equation is accomplished. The analytic solution of the integrals is obtained by employing asymptotic methods and the far field is presented. The effect of the Mach number is shown explicitly on the diffracted field.     

Essential oil composition of Valeriana officinalis L. roots cultivated in Iran. Comparative analysis between supercritical CO2 extraction and hydrodistillation

The composition of essential oil extracted from Valeriana officinalis L. roots growing wild in Iran was studied by hydrodistillation and supercritical CO2 extraction. Forty-seven components representing 89.3% and 35 constituents varying from 86.1% to 95.1% of the oil obtained by hydrodistillation and supercritical CO2 were identified, respectively. The major components in the extracted oil from supercritical CO2 were isovaleric acid (18.7-41.8%), valerenic acid (8.2-11.8%), acetoxyvaleranone (5.6-9.6%), (Z)-valernyl acetate (4.5-6.5%), bornyl acetate (2.3-7.7%) and valerenol (3.7-5.2%), whereas by hydrodistillation were bornyl acetate (11.6%), valerenic acid (8.0%), (Z)-valernyl acetate (7.9%) and acetoxyvaleranone (7.6%). The analysis of the extracts was performed by capillary GC and GC/MS.     

Highly selective transport of silver ion through a supported liquid membrane using calix[4]pyrroles as suitable ion carriers

Facilitated transport of silver ion across a supported liquid membrane (SLM) by calix[4]pyrroles, as selective ion carriers, dissolved in kerosene has been investigated. The influences of fundamental parameters affecting the transport of silver ion including ion carrier concentration in the membrane phase, thiosulfate concentration in strip phase, picric acid concentration in the feed phase, stirring speed of aqueous phases, type of membrane solvent and time of transport have been studied. In the presence of thiosulfate as a suitable metal ion acceptor in the strip phase and picrate ion as ion pairing agent in the source phase, transport of silver occurs almost quantitatively after 75 min. The selectivity and efficiency of silver transport from aqueous solution containing Cu²⁺, Mg²⁺, Ni²⁺, Ca²⁺, Zn²⁺, Pb²⁺, Co²⁺, Al³⁺, Hg²⁺, Cd²⁺, Fe³⁺, Fe²⁺ and Cr³⁺ were investigated.     

A Photoferroelectric Perovskite‐Type Organometallic Halide with Exceptional Anisotropy of Bulk Photovoltaic Effects

Perovskite‐type ferroelectrics composed of organometallic halides are emerging as a promising alternative to conventional photovoltaic devices because of their unique photovoltaic effects (PVEs). A new layered perovskite‐type photoferroelectric, bis(cyclohexylaminium) tetrabromo lead ( 1 ), is presented. The material exhibits an exceptional anisotropy of bulk PVEs. Upon photoexcitation, superior photovoltaic behaviors are created along its inorganic layers, which are composed of corner‐sharing PbBr₆ octahedra. Semiconducting activity with remarkable photoconductivity is achieved in the vertical direction, showing sizeable on/off current ratios (>10⁴), which compete with the most active photovoltaic material CH₃NH₃PbI₃. In 1 the temperature‐dependence of photovoltage coincides fairly well with that of polarization, confirming the dominant role of ferroelectricity in such highly anisotropic PVEs. This finding sheds light on bulk PVEs in ferroelectric materials, and promotes their application in optoelectronic devices.     

Antioxidant activity of different parts of Pistacia khinjuk Stocks fruit and its correlation to phenolic composition

The fruits of Pistacia khinjuk Stocks were collected from Ilam province, Iran. The aim of this study was to analyse antioxidant capacity and phenolic composition of different parts of P. khinjuk fruit. The antioxidant capacity of extracts was measured using different assays: ferric reducing ability of plasma, 2,2-diphenyl-1-picrylhydrazyl and nitric oxide radical scavenging. The phenolic composition of P. khinjuk fruit is reported for the first time. Amongst different parts of the fruit analysed in this study, hull extract contained the highest total phenolic and flavonoid contents. We observed a high correlation between different antioxidant activity and total phenolic and flavonoid contents. Therefore, antioxidant capacity can be related to total phenolic and flavonoid contents. A correlation analysis revealed that ascorbic acid, gallic acid, rutin, caffeic acid, ferulic acid and sinapic acid were the phenolic compounds mainly responsible for antioxidant power of the fruit extracts.     

Carbanion reactivity, kinetic and equilibrium studies of sigma-adduct formation and elimination in the reactions of 4-nitrobenzofurazan derivatives with nitroalkane anions

1H NMR studies are reported of the reactions in [2H(6)]-DMSO of 4-nitrobenzofurazan, 2a, and its 7-chloro- and 7-methoxy-derivatives, 2b and 2c respectively, with anions derived from nitromethane, 3, nitroethane, 4, and 2-nitropropane, 5. The initial reactions result in sigma-adduct formation by carbanion attack at the 5-position of 2a-c and in the case of reaction of 2a with 5 the adduct at the 7-position is also observed. These reactions may be followed by base catalysed elimination of nitrous acid to yield anionic alkene derivatives. Kinetic and equilibrium measurements of these reactions were made spectrophotometrically in methanol. The carbon nucleophilicities of the carbanions decrease in the order 3> 4> 5, as also found in their reactions with benzhydrylium cations, and are much lower than the nucleophilicities of some cyano-substituted carbanions. Comparison with corresponding sigma-adduct forming reactions of 1,3,5-trinitrobenzene, TNB, show that here 2 and TNB have similar electrophilicity, although the value of the intrinsic rate coefficient k(o) = 0.05, for reaction of 2 is rather lower than that, k(o) = 0.20, for the TNB reactions. Literature data suggest that for reaction with a variety of nucleophiles 2 and TNB show similar electrophilicities. Measurements of the rates of elimination of nitrous acid from some 5-adducts in methanol catalysed by methoxide ions are reported. Values of rate constants may be influenced both by steric requirements at the reaction centre and by the electronic effects of the 7-substituent.