Biosorption of Pb(II) using Gundelia tournefortii: Kinetics,equilibrium, and thermodynamics

In this paper, the feasibility of Gundelia tournefortii was studied as a novel, high-capacity biosorbent for removing lead ions from synthetic wastewater in a batch system. The effects of various parameters such as temperature, initial concentration, initial pH, biosorbent dosage, and contact time were investigated. Based on batch results, the optimum operating conditions were found to be pH 5, biosorbent dosage of 25 mg, and temperature of 20°C in the range of lead initial concentrations from 5 to 100 mg/L. The equilibrium contact time was 60 min. The biosorption mechanism can be well described by the Langmuir isotherm with a monolayer maximum adsorption capacity of 144.928 (mg/g) at 20°C and a pseudo-second-order kinetic model. Thermodynamic studies proved that the sorption process was physical, spontaneous, feasible, random, and exothermic. In the second step, the ability of artificial neural network (ANN) to predict the adsorption capacity of Gundelia tournefortii for the removal of Pb(II) from aqueous solution was examined. The model was developed using a three-layer feed-forward back-propagation (BP) network with 5, 12, and 1 neurons in the first, second, and third layers, respectively. The Levenberg–Marquardt BP training algorithm (LMA) was found to be the best BP algorithm with a minimum mean squared error of 0.000867 and a minimum relative squared error of 0.032771. The comparison between the results of ANN and experimental data showed that ANN has a superior performance (R²= of 0.998) in the prediction of the Pb(II) removal process.     

Proteomics analysis of liver pathological calcification suggests a role for the IQ motif containing GTPase activating protein 1 in myofibroblast function

To date the cellular and molecular mechanisms by which liver pathological calcifications occur and are regulated are poorly investigated. To study the mechanisms linked to their appearance, we performed a proteomics analysis of calcified liver samples. To this end, human liver biopsies collected in noncalcified (N), precalcified (P), and calcified (C) areas of the liver were subjected to weak ion exchange chromatography, SDS‐PAGE, and LC‐ESI MS/MS analyses. As we previously demonstrated that alpha‐smooth muscle actin (α‐SMA) expressing myofibroblasts were involved in liver pathological calcification, we performed a targeted analysis of actin cytoskeleton remodeling‐related proteins. This revealed dramatic changes in protein expression patterns in the periphery of the calcified areas. More particularly, we found that IQGAP1 and IQGAP2 proteins were subjected to major expression changes. We show that IQGAP1 expression within P and C areas of the liver correlates with the high abundance of myofibroblasts and that IQGAP1 is specifically expressed in these cells. In addition, we find that IQGAP1 is part of a protein complex including β‐catenin and Rac1 mainly in P and C regions of the liver. These results suggest that IQGAP1 may play a critical role in the regulation of cytoskeleton remodeling in liver myofibroblasts in response to liver injury and consequently impact on their function.     

Investigation of nitric acid treatment of activated carbon for enhanced aqueous mercury removal

In the present work, Hg(II) adsorption of a commercial activated carbon with and without nitric acid treatment was compared in a batch system. Iodine adsorption test and nitrogen adsorption and desorption experiments were carried out to investigate the changes in porous characteristics during acid treatment. Although the results for iodine adsorption of two samples were approximately similar, the increase in porous characteristics during acid treatment was determined by micropore volume and total pore volume of treated and untreated samples. To evaluate the effects of acid treatment on the surface functional groups, FTIR analysis for both types of activated carbons was performed, and showed oxidized surface for treated sample. Furthermore, composition of the gaseous by-product resulted from this treatment has been qualitatively analyzed using a FTIR device. Consequently, NO, NO₂, N₂O₄, N₂O, CO, and CO₂ were detected. Kinetic and equilibrium adsorption studies were performed considering effective parameters, including contact time, initial pH, and initial concentration. It can be seen that nitric acid treatment of activated carbon has enhanced Hg(II) adsorption capacity. Moreover, kinetic studies showed faster adsorption rate for treated activated carbon through changes in external surface rather than internal.     

Application of an air‐operated two impinging streams extractor in liquid‐liquid extraction and comparison with other contactor types

Extraction of succinic acid by means of normal butanol from its aqueous solutions (BSW), acetic acid by means of distilled water from kerosene (WAK) and iodine by means of kerosene from its aqueous solution (KIW) have been investigated in an air‐operated two impinging streams extractor (AOTISE) with spray nozzles. The effects of air flow rate, solutions flow rate, extractor length and diameter as well as modes of operation and impinging streams on extraction efficiency have been investigated. These results indicate that AOTISE is an efficient device for extraction processes. In addition, the overall volumetric mass transfer coefficients (K_La) are reported. The latter coefficients are important in design and may be used to compare the performance capability of various kinds of extractors.     

Identification of a nonlinear joint in an elastic structure using optimum equivalent linear frequency response function

As the main source of local nonlinearities, joints can lead to drastic changes in dynamic behavior of structures in a global scale. Finite element (FE) models often lack these nonlinearities and are incapable of representing nonlinear behavior. Therefore, the identification of nonlinear dynamic mechanical properties of the joint is necessary, in order to develop a faithful FE model of the structure. In the present work, dynamic parameters of a nonlinear joint are identified using an optimum equivalent linear frequency response function of the structure. A test rig, which includes a beam that can produce cubic stiffness spring characteristic as a nonlinear joint, is built, and nonlinear dynamic characteristics of the beam are identified. In addition to hardening behavior related to cubic stiffness, softening effects were also observed in some measured modes in which further investigation attributed that behavior to the presence of a bolt in the test rig.     

The role of addition of water to non-aqueous suspensions in electrophoretically deposited YSZ films for SOFCs

A dense film of YSZ was coated by electrophoretic deposition (EPD) method on graphite coated NiO–YSZ composite by acetone–ethanol media that were associated with different amount of deionized water. Addition of deionized water into the suspensions influenced significantly not only on the weight of deposition but also on the quality of the deposited surface. A maximum weight of deposition was obtained by addition 4% of water, where the most uniform surface was achieved. Zeta potential and weight of deposition had similar trends of variation. The sintered films were also show the homogeneous surface in this optimum percentage of water. Microstructures of electrophoretically deposited YSZ films were investigated by Scanning Electron Microscope (SEM) for green and sintered ones. In addition, the most homogeneous film had the minimum electrochemical impedance after consequence sintering.     

The role of electrical conductivity of substrate on the YSZ film formed by EPD for solid oxide fuel cell applications

Thick YSZ (8 mol% Y₂O₃–ZrO₂) films were coated by EPD, which was performed on non-conducting and graphite-coated NiO–YSZ composites. Weights of depositions had depended on the applied voltage linearly for both types of NiO–YSZ composites. In addition, weights of depositions were significantly higher when graphite-coated substrates were used. Uniform and dense depositions were successfully obtained by both methods. Adhesion strength was evaluated by micro hardness testing. However, it was observed that the interfacial adhesion was improved when graphite-coated substrates were used. The qualities of the deposited YSZ films were different after the subsequent sintering and cracks were developed on the surface of sintered YSZ films when non-conducting substrates were used. SEM observations showed that there were thicker YSZ films on the graphite-coated substrates than on the non-conducting ones. After the reduction process, NiO–YSZ composites were altered to Ni–YSZ cermet, which showed a good electrical conductivity all over it.     

Facilitated transport separation of propylene–propane: Experimental and modeling study

Supported liquid membrane, as one type of facilitated transport membranes, was used for the separation of propylene–propane mixtures. The effect of trans-membrane pressure and carrier concentration on membrane separation performance were evaluated in terms of mixed-gas selectivity, propylene and propane permeances and propylene and propane permeation fluxes. A general dimensionless model for the transport of components across the membrane was proposed and solved numerically by orthogonal collocation method. Experimental results showed that for a 70:30 (vol.%) propylene–propane mixture, at pressure 120 kPa and carrier concentration 20 wt.%, a propylene permeation flux of 1.46 × 10⁻⁴ mol/m² s was obtained. Mathematical results are in well agreement with experimental results. The average deviation between experimental and modeling results was found to be 5.3% for propylene permeation flux and 0.03% for propane permeation flux.     

Synthesis and spectroscopic and photoconduction characteristics of coaxial poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)−1,4‐phenylene vinylene] single‐walled carbon nanotube films with ohmic‐like transport attributes

Highly luminescent, core–shell, single‐walled carbon nanotube–poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)?1,4‐phenylene vinylene] (MEH‐PPV) one‐dimensional networks were synthesized by a multicycle unstable micellization method. The current–voltage data indicated that the charge transport within the nanowire network remained Ohmic, with the differential conductance scaling linearly with temperature in the temperature range of about 120 to 300 K. Further analysis based on the comparative study involving photoluminescence and Raman spectroscopic tests pointed to interchain interactions and nanotube–polymer interface as primary factors influencing the electronic characteristics of the processed samples. Likewise, steady‐state photoconduction tests confirmed that the heterointerface played a dominant role behind the increased photoresponse induced by exciton annihilation at a low bias regime. The study helped us identify the underlying physical mechanisms that controlled the optical, electrical, and photoconduction properties of the MEH‐PPV–carbon nanotube heteronetworks. Potentially, this will open a door to the development of next generation, low‐cost, all‐organic nanooptoelectronic devices and systems. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40029.