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At least 1,621 records · Page 90Linked to original sources
PubMed2004

Theoretical studies of the kinetics of methane hydrate crystallization in external electromagnetic fields.

Nonequilibrium molecular-dynamics (MD) simulations have been performed for the growth and dissolution of a spherical methane hydrate crystallite, surrounded by a saturated water-methane liquid phase, in both the absence and presence of external electromagnetic (e/m) fields in the microwave to far infrared range (5-7500 GHz) at root-mean square (rms) electric field intensities of up to 0.2 V/A. A rigid/polarizable potential was used to model water and a rigid/nonpolarizable model was utilized for methane. In the absence of a field, it was found that the average growth rate of the crystallite was approximately 0.32 water and 0.045 methane molecules per picosecond, evaluated over a 500 ps NPT simulation for three different initial geometries. Upon the application of an e/m field, it was found that no significant deviations from the zero-field crystal growth patterns were observed for rms electric field intensities of less than about 0.1 V/A, regardless of the field frequency. At, and above, this "threshold" intensity, it was found that dissolution took place. The mobility of the molecules in the system was enhanced by the e/m field, to the greatest extent for frequencies of 50-100 GHz. Furthermore, it was observed that there was a systematic frequency variation in the pattern of dipole alignment with the external field and this led to marked differences in the rate of dissolution.

Journal Article↗
PubMed1992

A portable pulsed electromagnetic field (PEMF) device to enhance healing of recalcitrant venous ulcers: a double-blind, placebo-controlled clinical trial.

A prospective, randomized, double-blind, placebo-controlled multicentre study assessed the clinical efficacy and safety of pulsed electromagnetic limb ulcer therapy (PELUT) in the healing of recalcitrant, predominantly venous leg ulcers. The portable device was used at home for 3 h daily during this 8-week clinical trial as an adjunct to a wound dressing. Wound surface area, ulcer depth and pain intensity were assessed at weeks 0, 4 and 8. At week 8 the active group had a 47.7% decrease in wound surface area vs. a 42.3% increase for placebo (P < 0.0002). Investigators' global evaluations indicated that 50% of the ulcers in the active group healed or markedly improved vs. 0% in the placebo group, and 0% of the active group worsened vs. 54% of the placebo group (P < 0.001). Significant decreases in wound depth (P < 0.04) and pain intensity (P < 0.04) favouring the active group were seen. Patients whose ulcers improved significantly after 8 weeks were permitted to continue double-blind therapy for an additional 4 weeks. Eleven active and one placebo patient continued therapy until week 12, with the active treatment group continuing to show improvement. There were no reports of adverse events attributable to this device. We conclude that the PELUT device is a safe and effective adjunct to non-surgical therapy for recalcitrant venous leg ulcers.

Adult↗
PubMed1994

Sinusoidal 60 Hz electromagnetic fields failed to induce changes in protein synthesis in Escherichia coli.

Escherichia coli JM83 [F- ara delta(lac-proAB) rpsL [phi 80d delta (lacZ)M15]] in midlog growth phase at 30 degrees C were exposed to 60 Hz sinusoidal magnetic field of 3 mT of nonuniform diverging flux, inducing a nonuniform electric field with a maximum intensity of 32 microV/cm using an inductor coil. Exposed and unexposed control cells were maintained at 30.8 +/- 0.1 degrees C and 30.5 +/- 0.1 degrees C, respectively. Quadruplicate samples of exposed and unexposed E. coli cells were simultaneously radiolabeled with 35S-L-methionine at 10 min intervals over 2 hr. Radiochemical incorporation into proteins was analyzed via liquid scintillation counting and by denaturing 12.5% polyacrylamide gel electrophoresis. The results showed that E. coli exposed to a 60 Hz magnetic field of 3 mT exhibited no qualitative or quantitative changes in protein synthesis compared to unexposed cells. Thus small prokaryotic cells (less than 2 microns x 0.5 micron) under constant-temperature conditions do not alter their protein synthesis following exposure to 60 Hz magnetic fields at levels at 3 mT.

Autoradiography↗
PubMedDate not supplied

[The electromagnetic fields of the base stations of mobile radio communication and ecology. The estimation of danger of the base station EMF for population and for bioecosystems].

The estimation of the danger for the population and for the bioecosistems of the electromagnetic conditions around of the base stations was given. The insufficiency of the scientific knowledge does not allow to guarantee the safety of the population and of the bioecosystems in the conditions of a round-the-clock long-term influence of EMF RF. WHO recommends to use "Precautionary principle".

Animals↗
PubMed2005

Pro-oxidant effects of extremely low frequency electromagnetic fields in the land snail Helix aspersa.

Pro-oxidant effects of extremely low frequency (ELF) 50-Hz magnetic fields were investigated in the land snail Helix aspersa exposed both in short-term laboratory treatments and under field conditions by maintaining the organisms in the proximity of a power line for up to 2 months. Oxidative perturbations were investigated as individual antioxidants (catalase, glutathione reductase, glutathione S-transferases, and total glutathione) and total scavenging capacity toward peroxyl radicals and hydroxyl radicals. Accumulation of lipid peroxidation products, destabilization of lysosomal membranes, and loss of DNA integrity were also evaluated as markers of cell damage. The overall results indicated an oxidative challenge caused by ELF magnetic fields with particularly prompt and sensitive responses for catalase, glutathione reductase, and the overall capability to neutralize peroxyl radicals. Cell injuries occurred to different extents according to duration and intensity of electromagnetic exposure and confirmed complex cause-effect relationships between pro-oxidant factors, efficiency of antioxidant defenses, and the onset of oxidative toxicity. This study highlights the importance of a multimarker approach for detecting a wide panel of biological responses, the necessity of investigating the long-term effects of early oxidative responses, and the role of ELF in enhancing susceptibility to other forms of pathologies or diseases.

Animals↗