A brief discussion about image quality and SEM methods for quantitative fractography of polymer composites.

The methodology for fracture analysis of polymeric composites with scanning electron microscopes (SEM) is still under discussion. Many authors prefer to use sputter coating with a conductive material instead of applying low-voltage (LV) or variable-pressure (VP) methods, which preserves the original surfaces. The present work examines the effects of sputter coating with 25 nm of gold on the topography of carbon-epoxy composites fracture surfaces, using an atomic force microscope. Also, the influence of SEM imaging parameters on fractal measurements is evaluated for the VP-SEM and LV-SEM methods. It was observed that topographic measurements were not significantly affected by the gold coating at tested scale. Moreover, changes on SEM setup leads to nonlinear outcome on texture parameters, such as fractal dimension and entropy values. For VP-SEM or LV-SEM, fractal dimension and entropy values did not present any evident relation with image quality parameters, but the resolution must be optimized with imaging setup, accompanied by charge neutralization.

Electro-audio-visual method for diagnosis and treatment.

This method can be applied to the non-drug treatment of diseases. It provides an exact evaluation of the healing effect by keeping the acupuncture point from overload. This method is realized by a bistable/monostable square wave oscillator. The electrical pulses for the treatment of the acupuncture point are delivered from the noninverted oscillator output. Their electrical parameters: frequency, pulse duration, rise time and coefficient of filling depend on the constantly changeable biophysical parameters of the acupuncture point, such as complex skin impedance (z), and total infrared skin thermal emission (te). Pulses from the inverted oscillator output are provided to the acoustic and visual channels. In the acoustic channel, the pulses are controlled only by amplitude. The visual output channel pulses apply to the amplitude- frequency circuit, where an amplitude-frequency analysis is performed. The output pulses of three electrical filters (low, middle and high frequency), control three sources of light, respectively red, green, and blue. Three colors blend on the white screen, as the color picture is modulated by the two biophysical parameters of the acupuncture point. These parameters are in a constant dynamics. The audio channel output information is delivered to the audio-information gate of the patient, reaching the Central Nervous System (CNS). The video channel output information is applied to the video-information gate and then to the patient's CNS, preparing it for appropriate therapeutical programs.

Slow force recovery after long-duration exercise: metabolic and activation factors in muscle fatigue.

To investigate the roles of metabolic and nonmetabolic factors in human muscle fatigue, two relatively brief nonexhausting exercise protocols that produced similar levels of moderate fatigue were used: short-duration exercise (SDE; 2-min sustained maximal voluntary contraction) and long-duration exercise (LDE; 15- to 20-min intermittent exercise). After exercise and during recovery, multiple potential mechanisms of fatigue were studied from measurements of voluntary, twitch, and tetanic forces; intracellular metabolites (using 31P-nuclear magnetic resonance spectroscopy); and electromyographic signals. The major findings were as follows. 1) After SDE, fatigue closely correlated with increased [Pi]. Both force and [Pi] recovered within approximately 5 min after exercise. 2) After LDE, force recovered slowly, with significant fatigue beyond 15 min after exercise; however, recovery of [Pi] was not slowed. 3) Electromyographic signals were little affected by either protocol. These findings suggest that multiple mechanisms contribute to moderate fatigue. Fatigue from SDE may arise primarily from metabolic mechanisms, whereas fatigue from LDE involves an additional slowly recovering nonmetabolic mechanism that may arise from impaired activation, beyond the cell membrane, at the level of excitation contraction-coupling.