Dual vortex breakdown in a two-fluid whirlpool

Looking for an optimal flow shape for culture growth in vortex bioreactors, an intriguing and impressive structure has been observed that mimics the strong swirling flows in the atmosphere (tornado) and ocean (waterspout). To better understand the flow nature and topology, this experimental study explores the development of vortex breakdown (VB) in a lab-scale swirling flow of two immiscible fluids filling a vertical cylindrical container. The rotating bottom disk drives the circulation of both fluids while the sidewall is stationary. The container can be either sealed with the still top disk (SC) or open (OC). As the rotation strength (Re) increases, a new circulation cell occurs in each fluid—the dual VB. In case SC, VB first emerges in the lower fluid at Re = 475 and then in the upper fluid at Re = 746. In case OC, VB first emerges in the upper fluid at Re = 524 and then in the lower fluid at Re = 538. The flow remains steady and axisymmetric with the interface and the free surface being just slightly deformed in the studied range of Re. Such two-VB swirling flows can provide efficient mixing in aerial or two-fluid bioreactors.

Thermodynamic cycles in the stratosphere

<p>Large-scale overturning mass transport in the stratosphere is commonly explained through the action of potential vorticity (PV) rearrangement in the flank of the stratospheric jet. Large-scale Rossby waves, with their wave activity source primarily in the troposphere, stir and mix PV and an overturning circulation arises to compensate for the zonal torque imposed by the breaking waves. In this view, any radiative heating is relaxational and the circulation is mechanically driven. Here we present a fully thermodynamic analysis of these phenomena, based on ERA-Interim data. Streamfunctions in a thermodynamic, log(pressure) – temperature space are computed. The sign of a circulation cell in these coordinates directly shows whether it is mechanically driven, converting kinetic energy to potential and thermal energy, or thermally driven, with the opposite conversion. The circulation in the lower stratosphere is found to be thermodynamically indirect (i.e., mechanically driven). In the middle and upper stratosphere thermodynamically indirect and direct circulations coexist, with a prominent semiannual cycle. A part of the overturning in this region is thermally driven, while a more variable indirect circulation is mechanically driven by waves. The wave driving does not modulate the strength of the thermally direct part of the circulation. This suggests that the basic overturning circulation in the stratosphere is largely thermally driven, while tropospheric waves add a distinct indirect component to the overturning. This indirect overturning is associated with poleward transport of anomalously warm air parcels.</p>

Photobiomodulation with Led 627nm associated to resveratron in cutaneous injuries of rats: a double-blind controlled clinical study.

Introduction: Drugs formulated as Resveratrol, associated with LED 627nm photobiomodulation, can increase the efficacy of active release, increased local circulation, cell proliferation and collagen synthesis, accelerating the healing process. Objective: To analyze the effects of 627nm LED photobiomodulation associated with Resveratrol on the tissue repair of induced wounds in Wistar rats. Methodology: We used 18 animals corresponding to the control groups, group LED 627nm with association to Resveratrol cream (GLed + Resv) 3 and 7 days. Results: Treatment with the use of LED associated with Resveratrol cream provided an efficient healing. In the statistical test, the significance level was observed between the groups of P <0.0156. In the multiple comparison between the pairs the Tukey’s test showed significance between the groups CG vs GLed627nm + Resv 7Day. Conclusion: The GLed + Resv group showed efficient inflammatory phase of healing, promoting a greater activation of fibroblasts and remodeling of the collagen fiber when compared to the control group.

Thermodynamic Cycles in the Stratosphere

Large-scale overturning mass transport in the stratosphere is commonly explained through the action of potential vorticity (PV) rearrangement in the flank of the stratospheric jet. Large-scale Rossby waves, with their wave activity source primarily in the troposphere, stir and mix PV and an overturning circulation arises to compensate for the zonal torque imposed by the breaking waves. In this view, any radiative heating is relaxational and the circulation is mechanically driven. Here we present a fully thermodynamic analysis of these phenomena, based on ERA-Interim data. Streamfunctions in a thermodynamic, log(pressure)–temperature space are computed. The sign of a circulation cell in these coordinates directly shows whether it is mechanically driven, converting kinetic energy to potential and thermal energy, or thermally driven, with the opposite conversion. The circulation in the lower stratosphere is found to be thermodynamically indirect (i.e., mechanically driven). In the middle and upper stratosphere thermodynamically indirect and direct circulations coexist, with a prominent semiannual cycle. A part of the overturning in this region is thermally driven, while a more variable indirect circulation is mechanically driven by waves. The wave driving does not modulate the strength of the thermally direct part of the circulation. This suggests that the basic overturning circulation in the stratosphere is largely thermally driven, while tropospheric waves add a distinct indirect component to the overturning. This indirect overturning is associated with poleward transport of anomalously warm air parcels.

Was the onset of interhemispheric AMOC slightly prior to Antarctic glaciation at the Eocene-Oligocene transition?

&lt;p&gt;A compilation of benthic &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O from the whole Atlantic and the Southern Ocean (Atlantic sector), shows two major jumps in the interbasinal gradient of d&lt;sup&gt;18&lt;/sup&gt;O (&amp;#916;&amp;#948;&lt;sup&gt;18&lt;/sup&gt;O) during the Eocene and the Oligocene: One at ~40 Ma and the second concomitant with the isotopic event of the Eocene-Oligocene transition (EOT), ~33.7 Ma ago. From previously published circulation models, we show that the first &amp;#916;&amp;#948;&lt;sup&gt;18&lt;/sup&gt;O jump reflects the thermal isolation of Antarctica associated with the proto-Antarctic circumpolar current (ACC). The second marks the onset of interhemispheric northern-sourced circulation cell, similar to the modern Atlantic meridional overturning circulation (AMOC). The onset of AMOC-like circulation probably slightly preceded (100-300 ky) the EOT, as we show by the high resolution profiles of &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O and &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C previously published from DSDP/ODP sites in the Southern Ocean and South Atlantic. We suggest that while the shallow proto-ACC supplied the energy for deep ocean convection in the Southern Hemisphere, the onset of the interhemispheric northern circulation cell was due to the significant EOT intensification of deepwater formation in the North Atlantic driven by the Nordic anti-estuarine circulation. This onset of the interhemispheric northern-sourced circulation cell could have prompted the EOT global cooling.&lt;/p&gt;

Nitrogen attenuation, dilution and recycling at the groundwater – surface water interface of a subtropical estuary inferred from the stable isotope composition of nitrate and water

Estuarine environments have a dynamic groundwater – surface water interface driven by terrestrial groundwater discharge, tidal cycles, waves and other processes. This interface also corresponds to an active biogeochemical environment. An assessment of discharging groundwater with elevated (>300 mg N L−1) NH4+ and NO3− concentrations at such an interface located in a subtropical estuary indicated that 80 % of the N was attenuated, one of the highest N removal rates (>100 mmol m−2 day−1) measured for intertidal sediments. The remaining N was also diluted by a factor of two or more by mixing before being discharged to the estuary. Most of the mixing occurred in a hyporheic zone in the upper 50 cm of the riverbed. However, groundwater entering this zone was already partially mixed (12–60 %) with surface water via a tidal circulation cell. Below the hyporheic zone (50–125 cm below the riverbed), NO3− concentrations declined slightly faster than NH4+ concentrations and δ15NNO3) and δ18ONO3 gradually increased, suggesting a co-occurrence of anammox and denitrification. In the hyporheic zone, δ15NNO3 continued to become enriched (consistent with either denitrification or anammox) but δ18ONO3 became more depleted (indicating some nitrification). The discrepancy between δ15NNO3 (23–35 ‰) and δ18ONO3 (1.2–8.2 ‰) in all porewater samples indicated that the original synthetic nitrate pool (δ15N ~ 0 ‰; δ18O ~ 18–20 ‰) had turned-over during transport in the aquifer before reaching the riverbed. Whilst porewater NO3− was more δ18O depleted than its synthetic source, porewater δ18OH2O) (−3.2 to −1.8 ‰) was enriched by 1–4 ‰ relative to rainfall-derived groundwater mixed with seawater. Isotopic fractionation from H2O uptake during the N cycle and H2O production during synthetic NO3− reduction are the probable causes for this δ18OH2O enrichment.