High performance graphene-poly (o-anisidine) nanocomposite for supercapacitor applications

Our previous exciting results on graphene (G)-conducting polymer (polyaniline (PANI) and polyethylenedioxythiophene (PEDOT)) supercapacitors have prompted the investigation of G-substituted conducting polymer nanocomposites used as electrode materials in supercapacitors. The solubility of ortho-substituted PANI derivatives in a few common solvents has allowed the fabrication of stretchable films by the casting technique. The G-poly (o-anisidine) (G-POA) nanocomposites were synthesized with different weight ratios of G to o-anisidine by chemical methods, and characterized by various techniques, such as, scanning electron microscopy, transmission electron microscopy, UV–visible spectroscopy, Raman spectroscopy, thermogravimetric analysis and cyclic voltammetry. The electrical conductivity and specific capacitance obtained for the G-POA nanocomposites were found to be dependent on the weight ratios of G to o-anisidine. The specific capacitance and the charging–discharging behavior of the POA and G-POA supercapacitors were investigated in a 2 M H₂SO₄, 0.2 M LiClO₄ and 1 M 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF₆) ionic liquid. The specific capacitance of 380 F g⁻¹ was calculated for the 1:1 weight ratio of G to o-anisidine based G-POA supercapacitor in 2 M H₂SO₄. The presence of the electron-donating group (–OCH₃) in the o-anisidine allows the electrons through the lone pair of nitrogen atoms to enhance the electronic charge transport inside the G-POA supercapacitor electrodes. However, the G-POA-based supercapacitors showed a 27% decrease in the specific capacitance in H₂SO₄ and 16% decrease in the ionic liquid (BMIM-PF₆) after 1000 cycles of charging and discharging. The higher stability and rate capability of the G-POA based supercapacitor in an ionic liquid (BMIM-PF₆) as compared to an aqueous electrolytic supercapacitor opens the door for the fabrication of stable supercapacitors for practical applications.     

Soft Magnetic Properties of Fe - (1 wt.%) Al Alloy Processed by Powder Metallurgy

A soft magnetic material (iron with 1 wt.% aluminum) has been developed using a powder metallurgy processing route. The addition of aluminum in iron has resulted in an alloy with significant grain growth during sintering and correspondingly superior magnetic properties characterized by a low coercivity (H_c≈0.9 Oe), a relatively high permeability (μ_max ≈ 5000) and a high saturated magnetic induction (B_s ≈ 13 kG at 8 Oe) after sintering at 1482°C for 12 hours. The effects of sintering time and temperature on the magnetic properties of this alloy have also been examined.     

Biosynthesis of xyrrolin, a new cytotoxic hybrid polyketide/non-ribosomal peptide pyrroline with anticancer potential, in Xylaria sp. BCC 1067

A gene from Xylaria sp. BCC 1067, pks3, that encodes a putative 3660-residue hybrid polyketide synthase (PKS)/non-ribosomal peptide synthetase (NRPS) was characterised by targeted gene disruption in combination with comprehensive product identification. Studies of the features of a corresponding mutant, YA3, allowed us to demonstrate that pks3 is responsible for the synthesis of a new pyrroline compound, named xyrrolin, in the wild-type Xylaria sp. BCC 1067. The structure of xyrrolin was established by extensive spectroscopic and spectrometric analyses, including low- and high-resolution MS, IR, (1)H NMR, (13)C NMR, (13)C NMR with Dept135, HMQC 2D NMR, HMBC 2D NMR and COSY 2D NMR. On the basis of the Pks3 domain organisation and the chemical structure of xyrrolin, we proposed that biosynthesis of this compound requires the condensation of a tetraketide and an L-serine unit, followed by Dieckmann or reductive cyclisation and enzymatic removal of ketone residue(s). Bioassays of the pure xyrrolin further displayed cytotoxicity against an oral cavity (KB) cancer cell line.     

Effect of mass transport on BOD removal in trickling filters

The effect of liquid-phase mass transport on BOD removal efficiency in a trickling filter is presented based on an analytical model of the process. It is shown graphically that liquid-phase mass transport resistances can significantly affect BOD removal for a given trickling filter. The applicability of the results presented to the analysis of experimental data and trickling filter design is discussed.     

Radial liquid distribution in cocurrent two-phase downflow in packed beds

Radial liquid distribution was measured experimentally for cocurrent, two-phase downflow in packed beds. The effects of bed length, water and air flow rates, and type of packing were determined. The experimental data were obtained in the gas-continuous, transition and pulsing trickling-flow regimes. For all finite air rates, the liquid velocity profiles were approximately flat with the maximum average velocity occurring at the center of the packed column. Increasing the air rate increased the center liquid velocity. The gas rate effect was more pronounced in shorter beds. At higher gas rates the liquid rate had less effect on the radial liquid distribution than at lower gas rates. Operation at higher liquid rates resulted in a flatter radial liquid veilocity profile. It was observed that the bed of pellets operated at high liquid rate and low gas rate was unstable. Increasing the bed height increased the stability of the system and a better liquid distribution was obtained. The effects of water flow rate, bed length, and packing type on the shape of the liquid velocity profiles were minor.     

Tracing the development of teacher knowledge in a design seminar: Integrating content,pedagogy and technology

Effective technology integration for teaching subject matter requires knowledge not just of content, technology and pedagogy, but also of their relationship to each other. Building on Schulman’s [Schulman, L. S. (1987). Knowledge and teaching: foundations for a new reform. Harvard Educational Review, 57(1), 1–22] concept of pedagogical content knowledge, we introduce a framework for conceptualizing Technological Pedagogical Content Knowledge—TPCK [Mishra, P., Koehler, M.J., (in press). Technological pedagogical content knowledge: A new framework for teacher knowledge. Teachers College Record]. We report the results of a semester-long investigation of the development of TPCK during a faculty development design seminar, whereby faculty members worked together with masters students to develop online courses. Quantitative discourse analysis of 15 weeks of field notes for two of the design teams show participants moved from considering technology, pedagogy and content as being independent constructs towards a richer conception that emphasized connections among the three knowledge bases. Our analyses suggests that developing TPCK is a multigenerational process, involving the development of deeper understandings of the complex web of relationships between content, pedagogy and technology and the contexts in which they function. Pedagogic, pragmatic, theoretical, and methodological contributions are discussed.