Serum procainamide analysis based on acetonitrile stacking by capillary electrophoresis

Stacking methods are important in capillary electrophoresis (CE) to overcome the poor detection limits. Cationic drugs are difficult to stack because they tend to interact with the capillary wall. As an example of the stacking of the cationic compounds, procainamide, an anti-arrhythmic drug, is analyzed in serum by CE using an acetonitrile treatment. Serum was deproteinized with acetonitrile containing quinine as an internal standard. About 12% of the capillary volume was filled with sample and separated using an electrophoresis buffer composed of triethanolamine, 2-(N-cyclohexylamino)ethanesulfonic acid (CHES) and 20% isopropanol, pH 8.2. Both the triethanolamine and the CHES were critical for the stacking. The addition of isopropanol improved the plate number for the procainamide and decreased the interfering compounds. Procainamide, its metabolite N-acetyl procainamide, and quinine were separated in about 7 min. The CE compared well with an immunoassay method.     

Tumor necrosis factor in synovial fluids of temporomandibular joint dysfunction syndrome

With the MTT tetrazolium WEHI 164 clone 13 cell cytotoxicity assay, we measured TNF alpha (tumor necrosis factor) activity in synovial fluids of TMJDS (Temporomandibular joint dysfunction syndrome). We found no detected TNF alpha level from 5 patients with muscle dysfunction, raised TNF alpha levels from 5 of 11 patients with internal derangement and from 9 of 11 patients with organic destruction (osteoarthritis). The findings of biologically active TNF alpha in synovial fluids of TMJDS suggest that TNF alpha may play a role in the pathogenesis of TMJDS.     

Adsorption Films of N-Hydroxyalkylated Ammonium Salts under Conditions of Hydrogen Sulfide Corrosion

Inhibitors of hydrogen-sulfide corrosion, namely, N-hydroxyethylated ammonium salts of some organic acids, form protective films at Cт3 steel (Z = 95 to 97%). Adsorbed and polymolecular layers of these films were revealed by electron microscopy and x-ray photoelectron spectroscopy. It was shown that the polymolecular layer can compensate for losses of the inhibitor from the sorbed layer.     

A method for calculating the thermal characteristics of silicon TVS-diodes in the pulse mode

The dependence of the thermal characteristics of TVS-diodes during the passage of the pulse overload has been studied. The time dependences of the pulse voltage limitation and current are analyzed. Based on the analysis of the dependences, the thermal characteristics of the TVS-diode are calculated. It is shown that the parameters of the TVS-diodes deteriorate on reaching a current density of 160–300 A/cm² and critical temperature of 250–300°С. The dependences of the thermal resistance and critical temperature of the TVS-diodes on the current density and the pulse duration are presented.     

Reliability prediction of the fatigue life of a crankshaft

Crankshaft, the core element of the engine of a vehicle, transforms the translational motion generated by combustion to rotational motion. Its failure will cause serious damage to the engine so its reliability verification must be performed. In this study, the S-N data of the bending fatigue limit of a crankshaft are derived. To evaluate the reliability of the crankshaft, reliability verification and analysis are performed. For the purpose of further evaluation, the bending test of the original crankshaft is carried out, and failure mode analysis is made. The appropriate number of samples, the applied load, and the test time are computed. On the basis of the test results, Weibull analysis for the shape and scale parameters of the crankshaft is estimated. Likewise, the B10 life under 50% of the confidence level and the MTTF are exactly calculated, and the groundwork for improving the reliability of the crankshaft is laid. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Do-Hyun Jung received his B.S. and M.S. degrees in Mechanical Engineering from Ajou University in 1988 and 1990, respectively. He then obtained his Ph.D. degree from Changwon National University in 2006. Dr. Jung is currently an Adjunct Professor at the School of Mechanical Engineering of Sunmoon University, Korea. He also manages the Reliability Application Research Center of the Reliability Division of KATECH. Dr. Jung’s fields of study include fatigue, reliability, and remanufacturing issues.     

Testing the Role of Glutamate NMDA Receptors in Peripheral Trigeminal Nociception Implicated in Migraine Pain

The pro-nociceptive role of glutamate in the CNS in migraine pathophysiology is well established. Glutamate, released from trigeminal afferents, activates second order nociceptive neurons in the brainstem. However, the function of peripheral glutamate receptors in the trigeminovascular system suggested as the origin site for migraine pain, is less known. In the current project, we used calcium imaging and patch clamp recordings from trigeminal ganglion (TG) neurons, immunolabelling, CGRP assay and direct electrophysiological recordings from rat meningeal afferents to investigate the role of glutamate in trigeminal nociception. Glutamate, aspartate, and, to a lesser extent, NMDA under free-magnesium conditions, evoked calcium transients in a fraction of isolated TG neurons, indicating functional expression of NMDA receptors. The fraction of NMDA sensitive neurons was increased by the migraine mediator CGRP. NMDA also activated slowly desensitizing currents in 37% of TG neurons. However, neither glutamate nor NMDA changed the level of extracellular CGRP. TG neurons expressed both GluN2A and GluN2B subunits of NMDA receptors. In addition, after removal of magnesium, NMDA activated persistent spiking activity in a fraction of trigeminal nerve fibers in meninges. Thus, glutamate activates NMDA receptors in somas of TG neurons and their meningeal nerve terminals in magnesium-dependent manner. These findings suggest that peripherally released glutamate can promote excitation of meningeal afferents implicated in generation of migraine pain in conditions of inherited or acquired reduced magnesium blockage of NMDA channels and support the usage of magnesium supplements in migraine.