Magnetic-based purification system with simultaneous sample washing and concentration

Simultaneous washing and concentration of magnetic microparticles was demonstrated using a rotational magnetic system under a continuous-flow condition. The rotation of periodically arranged permanent magnets close to a fluidic channel carrying a suspension of magnetic particles allows the trapping and releasing of particles along the fluidic channel in a periodic manner. Each trapping and releasing event resembles one washing cycle in conventional biological assays. Concentration efficiencies of 99.75?±?0.083% at a flow rate of 200 µl/min and 88.10?±?3.17% at a flow rate of 1,000 µl/min and a purification efficiency of 99.10?±?4.3% at a flow rate of 900 µl/min were achieved.     

Validation of a fast scanning technique for corrosion inhibitor selection: influence of cross‐contamination on AA2024‐T3

Aiming the assessment of novel, environmentally friendly corrosion inhibitors that can substitute chromate‐based ones, this work describes and validates a method for the rapid screening of water‐soluble inhibitors. The technique involves a fixed potential being applied between identical electrodes while immersed in an inhibitive solution and with the absence of a reference electrode. The current flowing between the electrodes is measured and the combined electrochemical response of the anodic and cathodic reactions, with and without the inhibitor, is then characterized. The incorporation of nine pairs of different metallic wires into a single assembly enables the effect of inhibitors on different metals to be assessed rapidly. The methodology presented allows approximately 30 electrochemical experiments to be performed per hour. In order to prove the usefulness of the proposed rapid screening technique (multielectrode), results obtained with the multielectrode are validated by comparison to the results obtained with a single electrode using only AA2024‐T3. The accuracy, reproducibility and parameter dependence has been assessed with the variation of inhibitor type and solution pH. Low absolute errors are found when studying inhibitors with good performance, giving confidence that no good inhibitors would be missed by this rapid screening method. The effect of cross‐contamination has been assessed and found to be negligible for almost all the pH range. Copyright © 2009 John Wiley & Sons, Ltd.     

Uncovering the Shuttle Effect in Organic Batteries and Counter‐Strategies Thereof: A Case Study of the N,N′‐Dimethylphenazine Cathode

The main drawback of organic electrode materials is their solubility in the electrolyte, leading to the shuttle effect. Using N,N′‐dimethylphenazine (DMPZ) as a highly soluble cathode material, and its PF₆^? and triflimide salts as models for its first oxidation state, a poor correlation was found between solubility and battery operability. Extensive electrochemical experiments suggest that the shuttle effect is unlikely to be mediated by molecular diffusion as commonly understood, but rather by electron‐hopping via the electron self‐exchange reaction based on spectroscopic results. These findings led to two counter‐strategies to prevent the hopping process: the pre‐treatment of the anode to form a solid–electrolyte interface and using DMPZ salt rather than neutral DMPZ as the active material. These strategies improved coulombic efficiency and capacity retention, demonstrating that solubility of organic materials does not necessarily exclude their applications in batteries.     

Clustering of search trajectory and its application to parameter tuning

This paper is concerned with automated classification of Combinatorial Optimization Problem instances for instance-specific parameter tuning purpose. We propose the CluPaTra Framework, a generic approach to CLUster instances based on similar PAtterns according to search TRAjectories and apply it on parameter tuning. The key idea is to use the search trajectory as a generic feature for clustering problem instances. The advantage of using search trajectory is that it can be obtained from any local-search based algorithm with small additional computation time. We explore and compare two different search trajectory representations, two sequence alignment techniques (to calculate similarities) as well as two well-known clustering methods. We report experiment results on two classical problems: Travelling Salesman Problem and Quadratic Assignment Problem and industrial case study.     

Laser Attenuation Correction for Planar Nephelometry Concentration Measurements

Experimental Techniques - Planar imaging of optically dense media using laser diagnostics is subject to measurement errors due to the occurrence of laser attenuation. Laser attenuation effects are...     

Syntheses of 1,1′-Bicobaltocene Salts of Tetracyano-P-Quinodimethane,Tetrabromoquinone, and Tetrabromodiphenoquinone; and the Structure of 1,1′-Bicobaltocene[Co(III)Co(III)][TCNQ]3

Abstract

A general theory of exciton (and electron) transport in perfect molecular crystals is discussed. The emphasis is on qualitative results and the elucidation of the effect of exciton and phonon bandwidth on the scattering of excitons and on transport. Various microscopic models are discussed in this light.     

Effects of angiotensin II receptor blockers in the coronary arteries of hypertensive rats: Analysis of elemental distribution using LEXRF

Hypertension is one of the major public health problems worldwide. It can cause severely alterations in artery structure and function such as vascular remodeling. Angiotensin II (Ang II) has been linked to vascular dysfunction. It has been shown that blockade of the Ang II type 1 receptor with an Ang II receptor blocker (ARBs) may reverse vascular pathology independently of blood pressure lowering. There is therefore a special interest in establishing whether antihypertensive treatment may correct in part or completely the structural and functional alterations of arteries. Several studies have shown regression of structural remodeling or of functional alterations of small arteries in spontaneously hypertensive rats (SHR) treated with ARBs agents. However, its efficiency was not verified at elemental level in the literature. Knowledge of the elemental distribution in tissues has a great importance in the study of diseases, because chemical imbalance can alter biological functions. Elemental semiquantitative microanalysis in the coronary artery of normotensive, SHRs, and SHRs rats treated with ARBs (losartan and olmesartan) was performed using low energy X-ray fluorescence maps acquired on TwinMic X-ray spectromicroscopy station, located at the Elettra synchrotron radiation facility. Morphological changes in coronary samples were also investigated. The results demonstrate that despite the antihypertensive agents used belong to the same class, their capacities to revert chemical and structural changes in the coronary arteries caused by hypertension are different.