Diving acclimatization refers to a reduced susceptibility to acute decompression sickness (DCS) in individuals undergoing repeated compression-decompression cycles. We postulated that mechanisms re...

https://www.physiology.org/doi/pdf/10.1152/japplphysiol.00952.2002

Heat stress attenuates air bubble-induced acute lung injury: a novel mechanism of diving acclimatization.

Diving acclimatization refers to a reduced susceptibility to acute decompression sickness (DCS) in individuals undergoing repeated compression-decompression cycles. We postulated that mechanisms responsible for the acclimatization are similar to that of a stress preconditioning. In this study, we investigated the protective effect of prior heat shock treatment on air embolism-induced lung injury and on the incidence of DCS in rats. We exposed rats (n=31) to a pressure cycle that induced signs of severe DCS in 48% of the rats, greater wet-to-dry ratio (W/D) of lung weight, and higher protein concentration in bronchoalveolar lavage (BAL) fluid compared with those in the control group (5.48±0.69 vs. 4.70±0.17 and 362±184 vs. 209±78 mg/L, respectively). Rats with DCS expressed more heat shock protein 70 (HSP70) in the lungs than those without signs of disease. Prior heat shock (n=12) increased the expression of HSP70 in the lung and attenuated the elevation of W/D of lung weight (5.03±0.17) after the identical decompression protocol. Prior heat shock reduced the incidence of severe DCS by 23% but failed to reach statistically significant (

Heat Stress Attenuates Air Bubble-induced Acute Lung Injury - A Novel Mechanism of Diving Acclimatization Short title: Air embolism after heat shock

Decompression illness (DCI) is an illness affecting divers subjected to reductions in ambient pressure. Besides a mechanical explanation to DCI, an inflammatory mechanism has been suggested. In this study, levels of interleukin (IL)-8, IL-6, IL-1 receptor antagonist (IL-1ra), secretory leukocyte protease inhibitor (SLPI), and neutrophil gelatinase-associated lipocalcin (NGAL) were measured in divers before and after a 2-mo period of daily diving. The divers were military conscripts and completed their diving period with no clinical symptoms of DCI. We found no change in IL-6 and IL1-ra but did find an increase in IL-8 and NGAL together with a decrease in SLPI levels. The findings suggest an inflammatory activation. This activation is not severe because no changes in IL-6 or IL-1ra were found. The increase in NGAL and IL-8 levels were interpreted as a sign of leukocyte activation. The decreased SLPI levels suggest an influence on the inflammatory defense mechanism. All in all, the findings of this study show a compensated activation of the inflammatory defense mechanism without loss of homeostasis of the inflammatory system.

Chronic hyperbaric exposure activates proinflammatory mediators in humans

The magnetic properties and 57Fe Mossbauer spectra of the compounds YFe11TiHx (x = 0, 1) were investigated. The magnetocrystalline anisotropy of YFe11Ti and its hydride was studied by analysing the hard and easy magnetization curves of single crystal samples in the temperature range 4.2–300 K. The spontaneous magnetization was determined in wide temperature range 4.2–650 K. It is established that at T = 4.2 K magnetic anisotropy constants K1 and K2 for YFe11TiH1 single crystal reach values of 25.8 K f.u.−1 and 0.24 K f.u.−1, respectively. The Mossbauer effect spectra of YFe11Ti and its hydride were analysed in terms of a model which takes into account the local environment of Fe atoms on three crystallographic sites (8f, 8j and 8i) and an influence of the random distribution of titanium on the 8i site. Upon hydrogenation both the hyperfine fields and the isomer shifts increase. These results are discussed in terms of the hydrogen-induced unit cell expansion and the electron charge transfer from the conduction band onto the H atoms.

https://iopscience.iop.org/article/10.1088/0953-8984/13/35/321/pdf

Magnetic anisotropy and Mössbauer effect studies of YFe11Ti and YFe11TiH

Atomistic simulation for the phase stability, site preference and thermal expansion of YFe12−xTx (T=Ti, V, Cr, Mn, Zr, Nb, Mo, W)

The structure and magnetic properties of RFe12−xMox series and their nitrides with R=Y,Gd,Nd and x=0.8,1.0,1.5,2.0,2.5 have been studied by x‐ray‐diffraction and magnetic measurements. It is found that with the increment of Mo content x, the lattice parameters increase, whereas the saturation magnetization, Curie temperature, and anisotropy field decreases in the RFe12−xMox series. Upon nitrogenation lattice parameters, saturation magnetization, and Curie temperature increase. Correspondingly, the easy c‐axis magnetocrystalline anisotropy of the Fe sublattice decreases in YFe12−xMoxNy and GdFe12−xMoxNy but increases in NdFe12−xMoxNy although its variation with the Mo content is the same as in their original counterparts. NdFe12−xMoxNy compound in the low Mo content shows great potential for permanent magnet applications.

Variation of magnetic properties as a function of Mo content in the RFe12−xMox series and their nitrides (R=Y, Nd, Gd)

A series of Y(Fe, M) 12 compounds and their hydrides and nitrides, where M  Ti, V, Mo, Cr, W, were prepared single phase. The effects of interstitial H and N atoms on the structural and magnetic properties have been studied by using the X-ray diffraction and magnetic measurements. The hydrides and nitrides still retain the tetragonal structure, but the unit cell volumes are expanded compared to their original counterparts. The saturation magnetization and Curie temperature are increased by both hydrogenation and nitrogenation, whereas the easy c -axis anisotropy related to the Fe-sublattice is enhanced in the hydrides but decreased in the nitrides.

Structural and magnetic properties of H and N modified Y(Fe, M)12 compounds (M Ti, V, Mo, Cr, W)

Hydrogen disproportionation, desorption, and recombination (HDDR) has been used as a pretreatment to prepare high performance Sm2Fe17Nx and NdFe10Mo2Nx compounds. Isotropic Sm2Fe17Nx and NdFe10Mo2Nx compounds with intrinsic coercivity larger than 12 and 4 kOe have been obtained by nitriding the HDDR treated powders, respectively. It is found that the magnetic properties are sensitively dependent on the time and temperature of the HDDR process, which determine the grain size, nitrogen content, and the amount of α‐Fe in the nitrides.

The effects of hydrogen disproportionation, desorption, and recombination on the structure and magnetic properties of Sm2Fe17Nx and NdFe10Mo2Nx compounds

Ping Xuan

Papers

Variation of magnetic properties as a function of Mo content in the RFe12−xMox series and their nitrides (R=Y, Nd, Gd)

Structural and magnetic properties of H and N modified Y(Fe, M)12 compounds (M Ti, V, Mo, Cr, W)

The effects of hydrogen disproportionation, desorption, and recombination on the structure and magnetic properties of Sm2Fe17Nx and NdFe10Mo2Nx compounds