Electric-magnetic field-induced aligned electrospun poly (ethylene oxide) (PEO) nanofibers

In this work, we report our attempt on the production of well-aligned nanofibers of poly (ethylene oxide) (PEO) by the introduction of magnetic field in the electric field by placing a cylindrical magnet within the electric field. Well-aligned nanofibers were obtained on top of the magnet. No particular structure could be associated with the other sides of the magnet. The aligned nanofibers were characterized by a host of characterization techniques such as optical and scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The diameter of the PEO nanofibers ranged between 500 and 1000 nm.     

Effect of viscous heating on heat transfer performance in microchannel slip flow region

Based on the superposition principle, an analytical solution for steady convective heat transfer in a two-dimensional microchannel in the slip flow region is obtained, including the effects of velocity slip and temperature jump at the wall, which are the main characteristics of flow in the slip flow region, and viscous heating effects in the calculations. The cases of constant heat flux boundary conditions and one wall as adiabatic and the other wall at constant heat flux input are studied. The solution method is verified for the cases where micro-scale effects are neglected. The effects of viscous heating on the temperature profiles and on the heat transfer performance are analyzed in detail. It is concluded that the effect of viscous heating, like an internal energy source, heats the fluid along the flow direction and severely distorts the temperature profiles. The effects of key parameters, such as the Brinkman and Knudsen numbers, on the Nusselt number, which expresses the heat transfer performance are investigated.     

Gp60 activation mediates albumin transcytosis in endothelial cells by tyrosine kinase-dependent pathway

We investigated the function of gp60, an endothelial cell membrane 60-kDa albumin-binding protein localized in caveolae, and the mechanism of its activation in regulating endothelial permeability of albumin. Gp60 organization on the bovine pulmonary microvessel endothelial cell (BPMVEC) surface was punctate as shown by immunofluorescence using an anti-gp60 antibody (Ab) conjugated with bisfunctional, N-hydroxysuccinimidyl fluorophore (Cy3). Addition of a secondary Ab to anti-gp60 Ab-treated BPMVEC induced cross-linking of gp60 as evident by increased size of fluorescent particles and cell surface gp60 clustering. Gp60 cross-linking also produced 2-3-fold increases in the endothelial cell uptake and the luminal to abluminal permeability of 125I-albumin as well as the fluid-phase tracer, horseradish peroxidase. The increased transendothelial permeability of macromolecules was the result of transcytosis as it was not associated with an increase in the paracellular pathway. Incubation of anti-gp60 Ab with BPMVEC at 37 degrees C caused internalization of gp60, and thereby reduced the uptake of the macromolecules. Activation of gp60 by either albumin (the gp60 ligand) or gp60 cross-linking induced the phosphorylation of both gp60 and caveolin-1 (the major structural caveolar protein) on tyrosine residues. Gp60 activation also phosphorylated the Src family tyrosine kinases pp60(c-Src) and Fyn. The activated pp60(c-Src) and Fyn co-immunoprecipitated with caveolin-1 in BPMVEC membrane. Protein tyrosine kinase (PTK) inhibitors, herbimycin A and genistein, prevented gp60-activated macromolecule uptake and transcytosis in a concentration-dependent manner, indicating the functional significance of the PTK pathway in activating albumin transcytosis. These findings indicate that activation of gp60 stimulates the Src PTK signaling pathway, and thus regulates the transcytosis of albumin across the endothelial cell monolayer.     

Serial networking connectivity in factory automation

This paper relates experience in serial networking of material handling systems and focuses on the issues of handshaking and timing.     

An adaptive generator excitation controller based on linear optimalcontrol

An adaptive excitation controller for a synchronous generator based on the linear optimal control theory is proposed. The generator operating conditions are tracked by a model whose parameters are identified every sampling interval using the actual input and output of the generator. The control is computed by solving a third-order Riccati equation and the identified model parameters. Studies on a single-machine infinite-bus system and a three-machine infinite-bus system show that the proposed controller exhibits better performances than an automatic voltage regulator (AVR) with a conventional power system stabilizer (PSS)     

Penetrative flow due to an isothermal vertical wall in a stable two-layer environment generated by a room fire

An experimental investigation has been carried out on the penetrative natural convection flow and thermal transport resulting from an isothermal vertical surface immersed in a stably stratified, twolayer, ambient medium, in which an essentially isothermal heated layer overlies a relatively cooler isothermal layer of the same fluid. Measurements of the thermal field are carried out for several surface temperatures and the corresponding isotherms obtained. The surface temperature is taken as lower than the upper layer temperature so that a downward natural convection flow is generated adjacent to the surface in the upper zone and the penetration of this flow into the lower region is investigated. Velocity and temperature profiles are measured to determine the mass flow rates across the interface between the two regions. The local heat transfer rates are also measured at various locations on the isothermal plate. For the surface temperature lying between the upper and lower layer temperatures, an upward flow is generated in the lower region and a downward flow in the upper region. The two flows collide near the interface, giving rise to transport across the interface.     

Spectral turbulence versus time-domain analysis of signal-averaged ECG used for the prediction of different arrhythmic events in survivors of acute myocardial infarction

INTRODUCTION: Spectral turbulence analysis of the signal-averaged ECG (SAECG) combines spectral analysis with statistical evaluation of spectrograms of individual parts of the QRS complex. It has been suggested that it may be superior to conventional time-domain analysis of the SAECG. METHODS AND RESULTS: This study compared the power of conventional time-domain (40 to 250 Hz) and spectral turbulence analyses of SAECG for the prediction of cardiac death, ventricular tachycardia, sudden arrhythmic death, and arrhythmic events (ventricular tachycardia or fibrillation, and/or sudden arrhythmic death) after acute myocardial infarction in 603 patients. The population excluded patients with bundle branch block and other conduction abnormalities. During the first 2 years of follow-up, there were 40 cardiac deaths, 21 cases of ventricular tachycardia, 1 sudden arrhythmic deaths, and 29 arrhythmic events. The positive predictive accuracy of spectral turbulence analysis was significantly higher than time-domain analysis for cardiac death at most levels of sensitivity (e.g., 26% vs 20% at 40% sensitivity, P < 0.05). The positive predictive accuracies of the two techniques were not statistically different for the prediction of ventricular tachycardia. For the prediction of sudden arrhythmic death and arrhythmic events, the positive predictive accuracy of spectral turbulence was better than that of time-domain analysis only at the higher levels of sensitivity (9% vs 2%, P < 0.001 for sudden arrhythmic death at 60% sensitivity, and 14% vs 11%, P < 0.05 for arrhythmic events at 60% sensitivity). CONCLUSIONS: Spectral turbulence analysis is essentially equivalent to time-domain analysis for the prediction of arrhythmic events after myocardial infarction. However, it performed significantly better than time-domain analysis for the prediction of cardiac death.     

Implementation and laboratory test results for an adaptive powersystem stabilizer based on linear optimal control

Implementation of an adaptive power system stabilizer (PSS) based on linear optimal control is described. The generator is identified in real time, and a special third-order discrete Riccati equation is solved in each sample interval. Because the output of the generator is fed back directly, the controller can track the system very fast. Experimental studies on a physical model of a micromachine alternator connected to a constant voltage bus through a transmission line are reported. The PSS was implemented using a multiprocessor architecture employing separate processors for identification, control, and man-machine interface. The various parameters are tuned to obtain the best performance under various disturbances. Test results show that the proposed PSS is very effective in damping out the system oscillation