Spontaneous Pneumomediastinum in nCOVID-19 infection: A case report

Spontaneous pneumomediastinum (SP) is a clinical entity characterized by the presence of interstitial air in the mediastinum. The purpose of this study was to further examine a rare SP case in a 60-year-old male, with COVID-19. In conclusion, SP is an uncommon complication in COVID-19, and the recognition of clinical characteristics is crucial since early identification plays a significant role in the maintenance or recovery of the disease.

Assessment of the effect of atmospheric pressure on the level and ground waters flow

The problem of understanding the interaction of river and ground water waters is intimately bound to questions of formation and unloading of ground waters in river network. The analysis of the previous researches showed that change of atmospheric pressure affects on the water level in observation wells and water discharge of springs. However, the mechanisms of this influence still weren't completely opened. For the solution of this task the complex laboratory, field and theoretical researches including overseeing by a drain, ground water level, atmospheric pressure and air pressure in an unsaturated (vadose) zone were conducted. On the basis of the conducted researches regularities the connecting size of change of ground water level and a drain of ground water waters with atmospheric pressure were received. As a result of generalization field and laboratory researches it was shown that the crucial role in formation of these regularities is played by the area located over a mirror of ground waters with the isolated interstitial air.With an increase in atmospheric pressure, the volume of interstitial air decreases, and at pressure drop volume increases. It, in turn, leads to change in the level and a flow of ground waters. The settlement formula for numerical assessment of variability of level ground depending on atmospheric pressure (barometric efficiency) and degree of air isolation was received from it in an unsaturated zone. As an indicator of isolation, a characteristic is used such as the volume of interstitial air involved in the inflow (outflow) of water into a measuring well or watercourse and not having direct contact with the atmosphere. Research results showed that, in addition to gravitational force in the movement of ground water and the formation of ground water inflow of rivers and lakes, another force plays a certain role - the pressure difference between atmospheric air and air in the unsaturated zone above the aquifer.

Porous Materials Under Shock Loading as a Two-Phase Mixture: The Effect of the Interstitial Air

Deformation and mixing of solid particles in porous materials are typical consequences under shock compression and are usually considered as the major contributors to energy dissipation during shock compression while a contribution from the interaction between the solid and gaseous phases attracts less attention. The present work illustrates the phase interaction process by mesomechanical hydrocode modeling under different conditions of the interstitial gaseous phase. A two-phase analytical approach focusing on the role of thermal nonequilibrium between the phases and an advanced two-phase model complement the mesomechanical analysis by demonstrating a similar trend due to the effect of pressure in the interstitial air.

Spontaneous pneumomediastinum following pneumonia in a 23-year-old male patient

<p>Spontaneous pneumomediastinum (SPM) is defined as the presence of interstitial air in the mediastinum without any apparent precipitating factor. We present a case of 23 year old male patient, who has been referred to our outpatient clinic with the complaints of sudden chest pain, dyspnea followed by pneumonia and was diagnosed as SPM. The patient was treated with ampicillin sulbactam (4 gr/day) and methylprednisolon (20 mg/day) for 4 days. and oral intake was stopped during treatment. Post treatment, it was observed that the crepitations were disappeared thoroughly and vesicular sounds were heard by oscultation. The control values of arterial blood gas was as following: pH:7,39 pO₂:95 mmHg, pCO₂:37 mmHg, SaO2: %97. In the 5th day his oral intake was started and he was discharged. </p>

Numerical Analysis of the Role of Snowpack in the Ozone Depletion Events during the Arctic Spring

The tropospheric ozone depletion events (ODEs) and the related enhancement of reactive bromine in the boundary layer were observed in the springtime of Arctic almost 40 years ago. It is found that various substrates in polar regions such as the snowpack are able to release bromine, which is responsible for the consumption of ozone in the boundary layer. In the present simulation, a snowpack module which represents the mass transfer between the ambient air and the snowpack is implemented in a box model, aiming to clarify the influences of the snowpack on ODEs and the associated bromine explosion in the ambient air as well as in the interstitial air of the snowpack. In the snowpack module, the processes including the deposition of bromine containing compounds onto the snowpack, the mass exchange between the snow interstitial air and snow particles, and the release of Br2 from the snowpack to the ambient air are parameterized by estimating the transfer resistances which an air parcel experiences when being transported through the boundary layer into the snowpack. The present model successfully captures the complete removal of ozone both in the boundary layer and in the snow interstitial air. The temporal and spatial distributions of bromine species such as Br2 are shown and compared with observations. By changing the properties of the snowpack, it is found that the size of snow grains, volume fraction of the liquid-like layer (LLL), and the rate of the mass exchange between the snow interstitial air and the snow particles are the critical parameters which determine the occurrence of ODEs. The simulation results show that a smaller size of the snow grains considerably accelerates the ozone depletion process. Moreover, the decrease of LLL volume fraction in snow grains is found to slow down the scavenging process of HOBr by the snow particles, which prohibits the occurrence of ODEs in the snowpack. In addition, according to the simulations with the modification of the snowpack thickness, the depletion of ozone in the ambient air is shown to be influenced more heavily by the bromine explosion occurring in the surface snow layers instead of the deep snow layers. The importance of each step in the mass transfer processes occurring between the boundary layer and the snowpack is identified by conducting a local concentration sensitivity analysis. It is shown that the snow chemistry occurring in the surface snow layers has a relatively larger impact on the depletion of ozone in the ambient air compared to that within the deep snow layers. Besides, during the period of the ozone depletion, the mixing ratio of ozone in the boundary layer is mostly influenced by the deposition of HOBr onto the surface snow layers and the release of Br2 from the snow layers close to the ground surface. In contrast to that, in the interstitial air of the surface snow layer, the uptake of HOBr by snow particles is indicated as the most dominant step for the ODE.

Formaldehyde (HCHO) in air, snow, and interstitial air at Concordia (East Antarctic Plateau) in summer

During the 2011/12 and 2012/13 austral summers, HCHO was investigated for the first time in ambient air, snow, and interstitial air at the Concordia site, located near Dome C on the East Antarctic Plateau, by deploying an Aerolaser AL-4021 analyzer. Snow emission fluxes were estimated from vertical gradients of mixing ratios observed at 1 cm and 1 m above the snow surface as well as in interstitial air a few centimeters below the surface and in air just above the snowpack. Typical flux values range between 1 and 2 × 1012 molecules m−2 s−1 at night and 3 and 5 × 1012 molecules m−2 s−1 at noon. Shading experiments suggest that the photochemical HCHO production in the snowpack at Concordia remains negligible compared to temperature-driven air–snow exchanges. At 1 m above the snow surface, the observed mean mixing ratio of 130 pptv and its diurnal cycle characterized by a slight decrease around noon are quite well reproduced by 1-D simulations that include snow emissions and gas-phase methane oxidation chemistry. Simulations indicate that the gas-phase production from CH4 oxidation largely contributes (66%) to the observed HCHO mixing ratios. In addition, HCHO snow emissions account for ~ 30% at night and ~ 10% at noon to the observed HCHO levels.

Formaldehyde (HCHO) in air, snow and interstitial air at Concordia (East Antarctic plateau) in summer

During the 2011/12 and 2012/13 austral summers HCHO was investigated for the first time in ambient air, snow, and interstitial air at the Concordia site located near Dome C on the East Antarctic plateau by deploying an Aerolaser AL-4021 analyser. Snow emission fluxes were estimated from vertical gradients of mixing ratios observed between 1 cm and 1 m above the snow surface as well as between interstitial air a few cm below the surface and in air just above the snow-pack. Typical flux values range between 1 to 2 × 1012 molecules m−2 s−1 at night and 3 to 5 × 1012 molecules m−2 s−1 at noon. Shading experiments suggest that the photochemical HCHO production in the snowpack at Concordia remains negligible compared to temperature-driven air–snow exchanges. At 1 m above the snow surface, the observed mean mixing ratio of 130 pptv and its diurnal cycle characterized by a slight decrease around noon are quite well reproduced by 1-D simulations that include snow emissions and gas phase methane oxidation chemistry.