Electrophoretic deposition of graphene oxide on carbon brush as bioanode for microbial fuel cell operated with real wastewater

Microbial fuel cell (MFC) is a promising technology for simultaneous wastewater treatment and energy harvesting. The properties of the anode material play a critical role in the performance of the MFC. In this study, graphene oxide was prepared by a modified hummer's method. A thin layer of graphene oxide was incorporated on the carbon brush using an electrophoretic technique. The deoxygenated graphene oxide formed on the surface of the carbon brush (RGO-CB) was investigated as a bio-anode in MFC operated with real wastewater. The performance of the MFC using the RGO-CB was compared with that using plain carbon brush anode (PCB). Results showed that electrophoretic deposition of graphene oxide on the surface of carbon brush significantly enhanced the performance of the MFC, where the power density increased more than 10 times (from 33 mWm^?2 to 381 mWm^?2). Although the COD removal was nearly similar for the two MFCs, i.e., with PCB and RGO-CB; the columbic efficiency significantly increased in the case of RGO-CB anode. The improved performance in the case of the modified electrode was related to the role of the graphene in improving the electron transfer from the microorganism to the anode surface, as confirmed from the electrochemical impedance spectroscopy measurements.     

Study of the effect of BDMA catalyst in the epoxy novolac curing process by isothermal DSC

Epoxy novolac/anhydride cure kinetics has been studied by differential scanning calorimetry under isothermal conditions. The system used in this study was an epoxy novolac resin (DEN431), with nadic methyl anhydride as hardener and benzyldimethylamine as accelerator. Kinetic parameters including the reaction order, activation energy and kinetic rate constants, were investigated. The cure reaction was described with the catalyst concentration, and a normalized kinetic model developed for it. It is shown that the cure reaction is dependent on the cure temperature and catalyst concentration, and that it proceeds through an autocatalytic kinetic mechanism. The curing kinetic constants and the cure activation energies were obtained using the Arrhenius kinetic model. A suggested kinetic model with a diffusion term was successfully used to describe and predict the cure kinetics of epoxy novolac resin compositions as a function of the catalyst content and temperature. Copyright © 2003 Society of Chemical Industry     

Performance of the decorrelator receiver for DS-CDMA mobile radio system employing RAKE and diversity through Nakagami fading channel

Multiple-access interference (MAI) and multipath fading are two of the most significant factors limiting the capacity and performance of direct-sequence code-division multiple-access (DS-CDMA) systems. In this paper, synchronous multiuser receivers that combine antenna diversity, RAKE reception, and a multipath decorrelator for MAI cancellation are analyzed in a Nakagami faded environment using a maximal ratio combiner or a selection combiner. A coherent binary phase-shift keying employing DS-CDMA is considered. Arbitrary branch correlation is also considered for any diversity order in the case of identical severity fading on the branches.     

Effect of functional group of ferrocene redox substance on the transport properties of newly designed ion exchange membrane prepared from polymer gel

A different newly designed cationic exchange polymer membrane and anionic exchange polymer membrane were introduced, and also the transport properties of these polymeric membranes were investigated in this study. The transport properties of these polymer membranes in contact with ferrocene redox derivatives were estimated by using electrochemical techniques such as cyclicvoltammetry, chronopotentiometry, and chronoamperometry techniques, respectively. The used ferrocene redox substances, which have different functional groups, were (Ferrocenylmethyl) trimethylamonium iodide, FcMA, Ferrocenedimethanol, FcDM, and Ferrocene carboxylic acid, FcCA. It indicated that the performance of a membrane depended on the content of polymer gel, anionic exchange polymer site (20 wt % and 50 wt %) or cationic polymer exchange site (20 wt % and 50 wt %), and the efficiency of the functional groups of cationic and anionic exchange polymer site as well. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Water and salt permeability of reinforcement polymer‐gel composite membrane

The charged mosaic polymer membrane (CMM) without reinforcement and the composite charged mosaic polymer membrane (CCMM) with reinforcement were investigated in terms of salt and water transport (permeability). The composite charged mosaic polymer membrane (CCMM) with reinforcement showed a unique transport behavior such as preferential material transport L_p and ω. Water permeability coefficient, L_p and salt permeability coefficient, ω were estimated by taking account of active layer thickness of composite polymer gel. The L_p and ω values of CCMM with reinforcement were larger than those of CMM without reinforcement. On the other hand, the reflection coefficient of CCMM, σ, showed negative value, which suggested preferential material transport to solvent transport. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Is prostate specific antigen density an important prognostic indicator for patients with prostate cancer treated with external beam therapy?

The purpose of this study was to determine if prostate specific antigen density (PSAD) is a predictor of outcome following external beam radiotherapy for prostate cancer, and to compare it with other prognostic factors. Between January 1990 and December 1993, 205 patients with T1-T3 adenocarcinoma of the prostate received a radical course of external beam irradiation, with no prior or adjuvant hormonal therapy. All patients had pre- and post-treatment serum prostate specific antigen (PSA) evaluation. They were followed up for at least 24 months. PSAD was defined as the ratio of pre-treatment serum PSA to the prostate volume, as determined from CT treatment planning scans. Prostate volumes were calculated using the prostate ellipse formula. Median PSA density was 0.37, with a range 0.01-6.7. Biochemical failure was defined as three consecutive rises in serum PSA, regardless of the magnitude of elevation. 4-year biochemical disease-free survival (BDFS) for patients with PSAD < or = 0.3 was 60%, compared with 22% for patients with PSAD > 0.3 (p = < 0.001). In a multivariate analysis, pre-treatment PSA (p = < 0.001), Gleason score (p = 0.002), and stage (p = 0.03) were independent predictors of BDFS, while PSAD was not an important prognosticator (p = 0.62). Pre-treatment serum PSA is the most important prognosticator of BDFS, following external beam radiotherapy, for patients with prostate cancer. PSA density did not predict treatment outcome.     

Radiation polymerization of acrylonitrile in a viscous system with styrene

Radiation polymerization of acrylonitrile in a viscous system with styrene was performed at ambient temperature by using γ‐rays. It is found that the overall rate of polymerization was accelerated after critical conversion due to the gel effect. As the molar fraction of styrene in monomer feed (f_St) is increased, both the total polymer conversion and molar fraction of acrylonitrile in the copolymer feed (F_AN) were decreased. The monomer reactivity ratios for acrylonitrile and styerne were determined to be r₁ (AN) = 0.25 and r₂ (St) = 2.0, respectively. The copolymers obtained were characterized by Fourier transformed infrared spectra (FTIR), X‐ray diffraction (XRD), scanning electron microscopy (SEM), ¹H‐NMR, and pyrolysis mass spectrometry (PMS). It was found that the slight addition of styrene to acrylonitrile strongly changes crystallinity, morphology, and thermal decomposition of the resulting polymer. ¹H‐NMR measurment of AN/St copolymer showed the appearance of aromatic proton signals and shifted the resonance of the methylene proton to lower chemical shifts. The mass spectra of AN/St copolymers showed fragments of pyrolysates corresponding to oligonitriles with styrene end groups. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 268–275, 2002; DOI 10.1002/app.10324     

Modification of leather properties by grafting. I. Effect of monomer chain on the physico‐mechanical properties of grafted leather

Although leather has a number of desirable properties such as thermal stability and fire retardancey, in addition to high toughness, it has a few drawbacks such as weight, high water absorption, poor soil and rot resistance, and nonuniformity. If these defects are overcome, leather's usefulness would be further enhanced and its competitive position with respect to synthetics would increase. This study reports the physical and mechanical properties of buffalo leather after chemical graft copolymerization with ethyl acrylate, butyl acrylate, and 2‐ethyl hexyl acrylate using benzoyl peroxide as an initiator. The optimum conditions for grafting (e.g., monomer and initiator concentrations, temperature and time of grafting, and solvent leather ratio) were extensively investigated. The study achieved outstanding properties for buffalo leather in reduction of water uptake after grafting, especially on using 2‐ethyl hexyl acrylate and butyl acrylate monomers. FT‐IR and solid ¹³C‐NMR for leather before and after grafting confirmed the grafting process.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1478–1483, 2003