Weak localization of light in superdiffusive random systems

Lévy flights constitute a broad class of random walks that occur in many fields of research, from biology to economy and geophysics. The recent advent of Lévy glasses allows us to study Lévy flights-and the resultant superdiffusion-using light waves. This raises several questions about the influence of interference on superdiffusive transport. Superdiffusive structures have the extraordinary property that all points are connected via direct jumps, which is expected to have a strong impact on interference effects such as weak and strong localization. Here we report on the experimental observation of weak localization in Lévy glasses and compare our results with a recently developed theory for multiple scattering in superdiffusive media. Experimental results are in good agreement with theory and allow us to unveil the light propagation inside a finite-size superdiffusive system.     

High‐Concentration Graphene Dispersions with Minimal Stabilizer: A Scaffold for Enzyme Immobilization for Glucose Oxidation

Modified acrylate polymers are able to effectively exfoliate and stabilize pristine graphene nanosheets in aqueous media. Starting with pre‐exfoliated graphite greatly promotes the exfoliation level. The graphene concentration is significantly increased up to 11 mg mL^?1 by vacuum evaporation of the solvent from the dispersions under ambient temperature. TEM shows that 75 % of the flakes have fewer than five layers with about 18 % of the flakes consisting of monolayers. Importantly, a successive centrifugation and redispersion strategy is developed to enable the formation of dispersions with exceptionally high graphene‐to‐stabilizer ratio. Characterization by high‐resolution transmission electron microscopy, X‐ray photoelectron spectroscopy, X‐ray diffraction, and Raman spectroscopy shows the flakes to be of high quality with very low levels of defects. These dispersions can act as a scaffold for the immobilization of enzymes applied, for example, in glucose oxidation. The electrochemical current density was significantly enhanced to be approximately six times higher than an electrode in the absence of graphene, thus showing potential applications in enzymatic biofuel cells.     

Chemical and electrochemical investigations of high carbon steel corrosion inhibition in 10 % HCl medium by quinoline chalcones

The corrosion inhibitive effect of 3-(3-oxo-3-phenyl-propenyl)-1H-quinolin-2-one (PPQ) and 3-(3-oxo-3-phenyl-propenyl)-1H-benzoquinolin-2-one (PPBQ) on high carbon steel (HCS) in 10 % HCl media was evaluated by chemical (weight loss) and electrochemical (electrochemical impedance spectroscopy and potentiodynamic polarization technique) measurements. The inhibition efficiencies obtained from weight loss and electrochemical measurements were in good agreement. The inhibition efficiency was found to increase with the increase in inhibitor concentration but decreased with rise in temperature. Potentiodynamic polarization studies revealed the mixed mode inhibition of inhibitors. The adsorption behavior of these inhibitors on the HCS surface was found to obey the Langmuir adsorption isotherm. The thermodynamic parameter values of free energy of adsorption (?G _ads) and enthalpy of adsorption (?H _ads) revealed that the inhibitor was adsorbed on the HCS surface via both chemisorption and physisorption mechanisms. The adsorption mechanism of inhibition was supported by spectroscopic techniques (UV–visible, FT-IR, and wide-angle X-ray diffraction), surface analysis (SEM–EDS), and adsorption isotherms.