OXYGEN REQUIREMENT FOR NEAR-UV MEDIATED CYTOXICITY OF α-TERTHIENYL TO ESCHERICHIA COLI AND SACCHAROMYCES CEREVISIAE

Abstract— The photosensitizing activity of α-terthienyl, a naturally occurring compound from Tagetes has been studied. Fluence-response curves for the effect of α-terthienyl and near-UV radiation on Escherichia coli have been prepared. Photosensitization of E. coli was enhanced in aerobic as compared to anaerobic conditions and exogenous superoxide dismutase had a slight protective effect. Sodium azide, a quencher of ¹O₂, protected yeast cells from photosensitization with α-terthienyl. The available evidence suggests that α-terthienyl acts as a photodynamic sensitizer in vivo.     

Selective separations by reactive ion exchange: Part 4. Preconcentration of cadmium and zinc by in situ precipitation as hexacyanoferrate(II) salts on gel and macroporous ion-exchange resins

The in situ precipitation of traces of cadmium(II) and zinc(II) ions as hexacyanoferrates from aqueous matrices was studied on conventional polystyrene gel and macroporous cation- and anion-exchange resins. Coprecipitation with each other or with copper(II) ions present in binary cation resins or in solution, and the influence of added nonprecipitating ions of the same charge type such as magnesium(II) were investigated. Microporous (gel) cation exchangers gave reasonable recoveries and macroporous cation exchangers gave very good recoveries; but macroporous anion exchangers performed best, suggesting macroporous hexacyanoferrate(II) resin as an ideal phase for collection/preconcentration of traces of Cu²⁺, Cd²⁺, Zn²⁺, and possibly Co²⁺, Ni²⁺, and Pb²⁺ from waters. As expected, very low yields were obtained with conventional anion exchange resin in the hexacyanoferrate form. Uniform distribution of Cu²⁺, Zn²⁺, and Cd²⁺ over macroporous anion-exchange resin phases were established by means of electron probe scans and taken as evidence for the formation of a uniform, well-developed precipitate layer covering the entire resin particle surface.     

α,α′-diiodosulfides a useful preparation of divinylic sulfides

Symmetric and unsymmetric divinylic sulfides can be prepared almost quantitatively by the elimination of HI by base from the corresponding α,α′-diiodosulfide. These molecules are quantitatively formed in situ from α,α′-$\text{bis}$trimethylsilosulfides and iodotrimethylsilane under mild conditions.     

Synthesis of polymerically bound catecholcarboxamide chelators for iron (III)

Tris(catecholcarboxamide) ligands were covalently linked to poly(vinyl amine—vinyl sulfonate sodium salt), and the iron binding capacity of the resultant polymers was found to exceed that of transferrin.     

Applying local model approach for tidal prediction in a deterministic model

In recent years, a practice of tidal prediction based on a deterministic model or by a time series forecasting model has been established. A deterministic model can predict tidal movement and capture the dynamics of the flow pattern over the entire domain. However, due to the simplification of model settings and near shore effects, the accuracy of the numerical model can diminish. Time series forecasting is capable of capturing the underlying mechanism that may not be revealed in the deterministic model simulation. However, such data‐driven forecast fails to maintain accuracy with the progress of forecast horizon. In this paper, a scheme that combines the advantages of these two methods is introduced. The model errors are forecasted to different time horizons using a data‐driven approach, and are then superimposed on the simulation results in order to correct the model output. Based on the proposed method, it is found that the accuracy is significantly improved with more than 50% of the errors removed on the average. Copyright © 2008 John Wiley & Sons, Ltd.     

On the nonlinear dynamics and control of flexible orbiting manipulators

The paper studies nonlinear dynamics and control of a class of space station based mobile flexible two-link manipulators, normally referred to as the Mobile Servicing System (MSS).The governing nonlinear, nonautonomous and coupled equations of motion are described first followed by the modal discretizations procedure. A parametric response study suggests situations with unacceptable levels of deflections and accelerations for certain proposed missions, as well as station libration and payload positioning errors.An inverse control technique is proposed to achieve high tracking accuracy of the MSS in presence of maneuver induced disturbances. The control strategy is so designed as to regulate the libration of the Space Station as well as to insure joints tracking of prescribed trajectories, while limiting the effect of the structural vibration during large slewing maneuvres of the MSS. Two different control schemes, both based on the feedback linearization technique, are developed and their relative merit assessed.This investigation was supported by the Centers of Excellence Program, Grant No. IRIS/C-8, 5-55380, and Natural Sciences and Engineering Research Council of Canada, Grant No. A-2181.     

Three‐Dimensional Branched and Faceted Gold–Ruthenium Nanoparticles: Using Nanostructure to Improve Stability in Oxygen Evolution Electrocatalysis

Achieving stability with highly active Ru nanoparticles for electrocatalysis is a major challenge for the oxygen evolution reaction. As improved stability of Ru catalysts has been shown for bulk surfaces with low‐index facets, there is an opportunity to incorporate these stable facets into Ru nanoparticles. Now, a new solution synthesis is presented in which hexagonal close‐packed structured Ru is grown on Au to form nanoparticles with 3D branches. Exposing low‐index facets on these 3D branches creates stable reaction kinetics to achieve high activity and the highest stability observed for Ru nanoparticle oxygen evolution reaction catalysts. These design principles provide a synthetic strategy to achieve stable and active electrocatalysts.