A SEM study on the galvanic protection of zinc-rich paints

The research is focused directly to the cahodic protection mechanism of zinc-rich paints (ZRP). It is based on a systematic scanning electron microscope (SEM) observation of cross-sections of several ZRP coatings exposed for different time intervals to a 3% (by weight) sodium chloride solution. The effect of vehicle (binder) used in the paint formula and the effect of zinc particle content are considered.As the anodic behaviour of zinc particles depends very closely on coating microstructure, SEM observation of the latter is very useful to investigate the galvanic performance of ZRP. This study confirms that high zinc particle contents and the use of ethyl silicate as a vehicle favour the degree and duration of the cathodic protection.Depending upon whether the zinc particles act anodically or not their attack mechanism is radically different. Accordingly, two attack mechanisms of the zinc particles are proposed.     

Immobilisation of different Candida rugosa lipases by adsorption onto polypropylene powder: application to chiral synthesis of ibuprofen and trans‐2‐phenyl‐1‐cyclohexanol esters

Candida rugosa lipases (CRLs) were immobilised by adsorption onto a commercial polypropylene powder EP100?. Two commercial CRLs from Sigma and Amano were used together with two CRLs obtained by fed‐batch fermentation using oleic acid as a carbon source (UAB‐CRL). Significant differences were observed in the isotherm adsorption patterns for the commercial and fermented lipases, probably caused by differences in their polysaccharide content. The commercial lipases showed a classical Langmuir adsorption pattern, whereas fed‐batch produced lipases with high polysaccharide content tended to conform to a BET multilayer adsorption equation. Immobilised CRLs also showed different behaviour in the resolution of two interesting pharmaceutical products: ibuprofen and trans‐2‐phenyl‐1‐cyclohexanol (TPCH) in the enantioselective esterification reaction in organic media. In the case of ibuprofen, CRLs showed important differences in terms of esterification rate, probably due to diffusional limitation effects caused by the high polysaccharide content present in UAB‐CRLs. In the case of TPCH, however, polysaccharide content did not appear to influence the esterification rate. A high enantioselective esterification was observed for all CRLs tested in the resolution of both products. © 2002 Society of Chemical Industry     

Hydrophilic interaction chromatography-based high-throughput sample preparation method for N-glycan analysis from total human plasma glycoproteins

Many diseases are associated with changes in the glycosylation of plasma proteins. To search for glycan biomarkers, large sample sets have to be investigated for which high-throughput sample preparation and analysis methods are required. We here describe a 96 well plate-based high-throughput procedure for the rapid preparation of 2-aminobenzoic acid (2-AA) labeled N-glycans from 10 microL of human plasma. During this procedure, N-glycans are released from glycoproteins and subsequently labeled with 2-AA without prior purification. A hydrophilic interaction chromatography (HILIC)-based solid phase extraction method is then applied to isolate the 2-AA labeled N-glycans, which can be analyzed by MALDI-TOF-MS, HPLC with fluorescence detection, and CE-MS. The relative standard deviation for the intrabatch repeatability and the interbatch repeatability of the sample preparation method remained below 7% and below 9%, respectively, for all peaks observed by HPLC. Similar results were obtained with MALDI-TOF-MS, where 47 N-glycans could be measured consistently. The 2-AA labeled N-glycans were additionally analyzed by a CE-ESI-Q-TOF-MS method, which featured high resolution and mass accuracy, allowing the unambiguous determination of the N-glycan compositions. Up to four times, 96 human plasma samples can be handled in parallel, which, together with the versatility of the 2-AA label, makes this procedure very attractive for glycomics analysis of larger sample cohorts.     

Anodic behaviour of a mercury electrode in aqueous 8-hydroxyquinoline solutions

Anodic dissolution of the hmde from 8-hydroxyquinoline (Ox) aqueous solutions at pH = 5.2 is attributed to the formation of insoluble organomercuric derivatives. The experimental results show that the process happens in two steps. The first one takes place with adsorption of electroactive species, while an insoluble product, which can produce the inhibition of the electrode process, is formed in the second one.     

Adaptive Controller for Single-Link Flexible Manipulators Based on Algebraic Identification and Generalized Proportional Integral Control

In this paper, we propose a fast online closed-loop identification method combined with an output-feedback controller of the generalized proportional integral (GPI) type for the control of an uncertain flexible robotic arm with unknown mass at the tip, including a Coulomb friction term in the motor dynamics. A fast nonasymptotic algebraic identification method developed in continuous time is used to identify the unknown system parameter and update the designed certainty equivalence GPI controller. In order to verify this method, several informative simulations and experiments are shown.     

Multiple-electrode method for estimating the polarization resistance in large structures

A new method for estimating the polarization resistance and the corrosion current from the Stern-Geary equation in cases where the applied signal distributes unevenly over a large real structure acting as working electrode is proposed. In addition to measurements of the current response to an applied potential pulse, the new method takes into account the distribution of polarization values over the working electrode (WE) surface. To this end, relevant information is provided by multiple reference electrodes placed at different points on the WE surface. The method allows estimation of the corrosion current for steel rebars embedded in large concrete structures.     

Running and Swimming Differently Adapt the BDNF/TrkB Pathway to a Slow Molecular Pattern at the NMJ

Physical exercise improves motor control and related cognitive abilities and reinforces neuroprotective mechanisms in the nervous system. As peripheral nerves interact with skeletal muscles at the neuromuscular junction, modifications of this bidirectional communication by physical activity are positive to preserve this synapse as it increases quantal content and resistance to fatigue, acetylcholine receptors expansion, and myocytes’ fast-to-slow functional transition. Here, we provide the intermediate step between physical activity and functional and morphological changes by analyzing the molecular adaptations in the skeletal muscle of the full BDNF/TrkB downstream signaling pathway, directly involved in acetylcholine release and synapse maintenance. After 45 days of training at different intensities, the BDNF/TrkB molecular phenotype of trained muscles from male B6SJLF1/J mice undergo a fast-to-slow transition without affecting motor neuron size. We provide further knowledge to understand how exercise induces muscle molecular adaptations towards a slower phenotype, resistant to prolonged trains of stimulation or activity that can be useful as therapeutic tools.     

Potential-dependent water orientation on Pt(1 1 1) stepped surfaces from laser-pulsed experiments

Coulostatic potential transients induced by nanosecond pulsed laser irradiation on Pt(1 1 1) stepped surfaces in perchloric acid solutions are analyzed here. The results provide unique information on the effect of the structure of the metal surface on the potential-dependent water reorientation at the electrified interphase. The most significant information is obtained from the sign and shape of the laser-induced transients. The existence of two potentials where the transient is zero can be related to the local properties of the surface, i.e. the existence of two local potentials of zero free charge, corresponding to the step and terrace sites. The dependency of these quantities with the step density is studied in detail. In addition, it is found that the presence of steps significantly slows down the coulostatic response at potentials in the double-layer region, which has been interpreted as a decrease in the velocity of water reorganization. The corresponding relaxation time is estimated and its dependency with the step density is also analyzed.