Coarsening of antiferromagnetic domains in multilayers: the key role of magnetocrystalline anisotropy.

The domain structure of an antiferromagnetic superlattice is studied. Synchrotron Mössbauer and polarized neutron reflectometric maps show micrometer-size primary domain formation as the external field decreases from saturation to remanence. A secondary domain state consisting mainly of at least 1 order of magnitude larger domains is created when a small field along the layer magnetizations induces a bulk-spin-flop transition. The domain-size distribution is reproducibly dependent on the magnetic prehistory. The condition for domain coarsening is shown to be the equilibrium of the external field energy with the anisotropy energy.

Respiratory symptoms and lung function abnormalities among machine operators in automobile production.

This cross-sectional study was designed to assess differences in prevalence of respiratory symptoms and lung function between machine operators exposed to semisynthetic or soluble metal-working fluids (MWFs) and unexposed assemblers and to assess exposure-response relationships with MWF type, total aerosol, endotoxin, culturable bacteria and fungi. We evaluated 183 machine operators and 66 assemblers from one large automobile transmission plant using questionnaires, spirometry data, and cross-shift assessment of both lung function and respiratory symptoms. We found that airborne exposures to total aerosol, endotoxin, culturable bacteria and fungi were higher in machine operations than in the assembly area. There was a correlation between bulk and airborne culturable bacteria, but not between bulk and airborne culturable fungi. Machine operators had significantly more usual cough, usual phlegm, work-related chest tightness and post-shift symptoms of chest tightness, throat irritation, and cough compared with assemblers. We found exposure-response relationships between respiratory symptoms and total aerosol, as well as culturable fungi and bacteria. Associations with endotoxin were not strong or consistent, possibly because airborne levels were generally low. Cross-shift lung function decrements did not differ between machine operators and assemblers and there were no associations with MWF or specific exposures. The finding of respiratory symptoms at low levels of exposure in this study suggests the need to re-assess total aerosol thresholds. Associations between airborne fungal exposures and respiratory symptoms need further study to characterize sources of exposure other than MWF in machining operations.

Pulmonary effects of machining fluids in guinea pigs and mice.

Acute pulmonary effects of inhalation exposure to (unused) neat and in-use metalworking fluids (MWF) were studied to evaluate the potency of characterized MWF in terms of their effects on breathing and lung inflammation. Inhalation exposure of guinea pigs caused dose-dependent changes in respiratory rate and volume that were used to quantify potency. In-use MWF was consistently more toxic than the corresponding neat MWF. Significant predictors of respiratory responses were whether MWF was neat or in-use (p = 0.0001), exposure concentration (p = 0.022), MWF formulation (p = 0.031), and the particular in-use MWF tested (p = 0.032). Inhalation exposures to MWF biocides resulted in dose-dependent sensory irritation responses. Guinea pig studies revealed significant inflammation resulting from MWF exposure marked by change in bronchoalveolar lavage (BAL) fluid from 3% neutrophils (controls) to 60-79% (MWF-exposed) and 25-fold increase in total BAL cells. The in-use MWF ranged in endotoxin concentration from 280 to 1.7 x 10(5) endotoxin units (EU)/mL. To investigate the role of endotoxin, studies were carried out in mice sensitive (SEN) and resistant (RES) to endotoxin. SEN mice revealed a dose-dependent 10,000-fold increase in BAL neutrophils and a 100-fold increased concentration of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) following inhalation exposure to in-use MWF. This inflammatory response was not observed with exposure to neat MWF or with sham exposure. RES mice demonstrated virtually no response to the inhaled MWF for total cells, neutrophils, IL-6, or TNF-alpha. Removal of microorganisms by filtration of the in-use MWF did not change the responses observed in either strain. These studies demonstrate that lung inflammation may be an important outcome from exposure to in-use MWF and that endotoxin is a toxicant of importance.

[Chronic hypoxia and tissue adaptation (excluding the right heart) in chronic obstructive bronchopathies]. / Hypoxie chronique et souffrance tissulaire (à l'exclusion du coeur droit) dans les bronchopathies chroniques obstructives.

In this report, the authors review the diverse mechanisms of compensation to chronic hypoxaemia, that is principally a displacement to the right of the haemoglobin dissociation curve and polycythaemia which tends to improve the supply of oxygen to the cells. The tissue effects of this chronic hypoxaemia are specified (excluding the right heart). As regards the left ventricle, ventricular function seems to be conserved until late yet there is a risk of arrhythmias which appears to increase proportionately to the degree of desaturation. Chronic respiratory failure produces clear cut neuropsychological deficits which correlate with the degree of hypoxaemia as well as problems with the quality of life and interference with memory. These troubles seem to be limited or even partially reversed by oxygen therapy. These patients also have troubles with urine output of water and sodium and there are also sexual problems as well as peripheral neuropathy.